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Objective Despite improvement in management of primary rectal cancer, 2.6–32% of patients develop local recurrence. A proportion of these patients can be amenable to salvage surgery. The present article reviews the evidence for and against the surgical management for local recurrence of rectal cancer, the role of adjuvant and intraoperative radiotherapy (IORT), and evaluates short and long-term outcomes. Method A literature search was performed using Medline, Embase, Ovid and Cochrane database for studies between 1980 and 2005 assessing surgical management of local recurrence of rectal cancer and the evidence was critically evaluated. Results Nearly 50% of rectal cancer recurrences are local and are therefore potentially amenable to curative resection. Preoperative imaging is important for appropriate selection of patients for surgery and preoperative adjuvant therapy is essential. Five-year survival following resection ranges from 18% to 58% with 5-year survival following complete resection of over 35% though morbidity ranges from 21% to 82%. Neoadjuvant radiotherapy is beneficial and IORT may have a contributory role in treatment. Aggressive surgical treatment favourably affects quality of life and is cost effective. Conclusion Surgery for local recurrence can result in significant long-term survival with acceptable morbidity and improved quality of life in appropriately selected patients. Assessment in a specialist centre familiar with these techniques is essential. [ABSTRACT FROM AUTHOR]

Objective Guidelines for the urgent referral of patients with suspected colorectal cancer were introduced in 2000. They aimed to facilitate the prompt diagnosis and treatment of patients with symptoms suggestive of malignant disease. Recent assessment of these guidelines has suggested that although they identify 9–14% of patients with colorectal cancer, they may be used inappropriately and may lead to delays in treatment for those patients with cancers whose symptoms do not fit the guidelines. We aimed to assess the effect of introducing a single pathway for all referrals irrespective of indicated urgency. Method All referral letters to a single consultant colorectal surgeon over a 6-month period were coded ‘urgent’ irrespective of the indicated urgency on the original referral letter. Data was collected prospectively on 47 patients diagnosed with colorectal cancer identified over the trial period. Patient demographics, the mode of presentation, urgency of referral and waiting times were documented. Results Following the introduction of the common urgent referral pathway, no patient waited longer than 62 days from referral to treatment or 31 days from the decision to treat to first treatment, thus meeting government targets introduced in 2005. Conclusion The introduction of the urgent referral guidelines has accelerated the referral pathway for patients with symptoms suggestive of colorectal cancer, although this is at the expense of the majority of patients who present via conventional pathways. The introduction of a common urgent pathway allows prompt diagnosis and treatment and is of particular benefit for the majority of patients not referred via the 2-week standard. Until a more accurate method of identifying the highest risk patients is implemented, we suggest that all patients are seen on an urgent basis. [ABSTRACT FROM AUTHOR]

Introduction It has generally been considered that open pelvic surgery is almost always easier in female subjects because of anatomical differences facilitating surgical access. In contrast, the male pelvis has been considered to be narrower and deeper. The objective of this study was to assess magnetic resonance imaging (MRI) pelvimetry in patients with rectal cancer in whom any difference in pelvimetry may potentially affect operative management. Male and female pelvic bony dimensions were compared. Method A cohort of 186 patients (112 males and 74 females) with rectal cancer who had been recruited prospectively to the Magnetic Resonance Imaging and Rectal Cancer European Equivalence Study (MERCURY Study) were assessed. Complete digital images were available on these patients. A comparison of the pelvic dimensions was made between the sexes using 16 dimensions measured on the MRI workstation using the mid-sagittal and axial images. Results There was no significant difference and considerable overlap between the sexes with respect to each of the 14 parameters measured from the preoperative sagittal MRI scan. However, there was a highly significant difference between the interspinous and intertuberous transverse diameter of the pelvis ( P < 0.0001). Conclusion Outcome after surgery may be influenced by the technical difficulty of the operation and this had been thought to be partly affected by the pelvic size. In this cohort of 186 patients, the only difference seen between the sexes, was in the transverse mid-inlet and pelvic outlet diameter. [ABSTRACT FROM AUTHOR]

Objective Transanal endoscopic microsurgery (TEM) is a minimally invasive technique for excision of selected benign and malignant rectal neoplasms. It is considered a safe and effective treatment but recurrence rates of 1–13% are reported for benign lesions. The aim of this study was to assess risk factors for local recurrence of benign rectal lesions and to evaluate mortality and morbidity following TEM. Method Data were prospectively collected from all patients undergoing TEM for benign adenomas from January 1998 to March 2005. The procedure was performed by a single surgeon and patients were regularly followed up. Results One hundred and forty-six procedures were included, with a median patient age of 74 years (range 22–92 years). The mean lesion area was 16 cm2 (range 0.3–150 cm2) and the median distance from the dentate line was 9 cm (range 0–17 cm). Immediate complications included bleeding (six) and acute urinary retention (six). There has been one (0.68%) procedure-related death. After a median follow up of 39 months (range 4–89 months) there have been seven recurrences (4.8%), recurring at a mean time of 23.3 months (range 5–48 months). Only microscopic involvement of the circumferential resection margin was found to be significantly associated with recurrence ( P = 0.0059). Recurrence was not associated with age, size of lesion, previous treatment, severity of dysplasia or use of the harmonic scalpel. Conclusion TEM is a safe and effective treatment for benign rectal adenomas. Circumferential resection margin involvement is associated with recurrence, which tends to occur late. Therefore extended follow up is recommended. [ABSTRACT FROM AUTHOR]

Vasoactive intestinal peptide (VIP) is a secretagogue that mediates chloride secretion in intestinal epithelia. We determined the relative potency of VIP and related peptides in the rectal gland of the elasmobranch dogfish shark and cloned and expressed the VIP receptor (sVIP-R) from this species. In the perfused rectal gland, VIP (5 nM) stimulated chloride secretion from 250 ± 66 to 2,604 ± 286 μeq·h-1·g-1; the relative potency of peptide agonists was VIP > PHI = GHRH > PACAP > secretin, where PHI is peptide histidine isoleucine amide, GHRH is growth hormone-releasing hormone, and PACAP is pituitary adenylate cylase activating peptide. The cloned sVIP-R from shark rectal gland (SRG) is only 61% identical to the human VIP-RI. It maintains a long, extracellular NH2 terminus with seven cysteine residues, and has three N-glycosylation sites and eight other residues implicated in VIP binding. Two amino acids considered important for peptide binding in mammals are not present in the shark orthologue. When sVIP-R and the CFTR chloride channel were coexpressed in Xenopus oocytes, VIP increased chloride conductance from 11.3 ± 2 to 127 ± 34 μS. The agonist affinity for activating chloride conductance by the cloned receptor was VIP > GHRH = PHI > PACAP > secretin, a profile mirroring that in the perfused gland. The receptor differs from previously cloned VIP-Rs in having a low affinity for PACAP. Expression of both sVIP-R and CFFR mRNA was detected by quantitative PCR in shark rectal gland, intestine, and brain. These studies characterize a unique G protein-coupled receptor from the shark rectal gland that is the oldest cloned VIP-R. [ABSTRACT FROM AUTHOR]

This article provides a broad review of osmoregulation in elasmobranchs for non-specialists, focusing on recent advances. Marine and euryhaline elasmobranchs in seawater regulate urea and other body fluid solutes (trimethylamine oxide (TMAO), Na + , Cl - ) such that they remain hyper-osmotic to their environment. Salt secretions of the rectal gland and excretions in the urine compensate for continuous inward diffusion of environmental salts. Freshwater and euryhaline elasmobranchs in fresh water synthesise less urea and retain less urea and other body fluid solutes compared to marine elasmobranchs and thus have relatively lower osmolarity. Electrolyte uptake at the gills and kidney reabsorption of salts maintain acid–base balance and ionic consistency. The role of the gills, kidney, liver and rectal gland in elasmobranch osmoregulation is reviewed. The ontogeny of osmoregulatory systems in elasmobranchs and the contribution of drinking and eating processes in maintaining osmotic consistency are discussed. Recommendations for future research are presented. [ABSTRACT FROM AUTHOR]

The article discusses prostate cancer which is the most commonly diagnosed malignancy among men. Age, ethnicity and family history are the risk factors associated with the development of prostate cancer. A pyramid-shaped gland with a base facing upward toward the floor of the bladder and the apex lying above the membranous urethra is the prostate. The digital rectal examination and measurement of prostate specific antigen can detect prostate cancer.

Abstract: Males of Bactrocera dorsalis (Diptera: Tephritidae) are attracted strongly to and feed compulsively on methyl eugenol (1,2-dimethoxy- 4 -(2-propenyl)benzene), a highly potent male attractant. Pharmacophagy of methyl eugenol results in the production of phenylpropanoids 2-allyl-4,5-dimethoxyphenol and (E)-coniferyl alcohol that are sequestered and stored in the rectal gland prior to release as sex pheromonal components during mating at dusk. While these pheromonal components have also been detected in the hemolymph and crop of methyl eugenol-fed males, there is currently little information on the transport of these compounds from the crop to rectal gland in male B. dorsalis. Therefore, using physiological techniques such as parabiosis, rectal gland transplantation and hemolymph transfusion coupled with gas chromatography–mass spectrometry (GC-MS) analyses, we were able to ascertain and confirm the role of the hemolymph in the transport of these sex pheromonal components from the crop to the rectal gland. Further, the temporal profile of these methyl eugenol-derived bioactive compounds in the hemolymph also shows an increase with time post-methyl eugenol-feeding, i.e., 2-allyl-4,5-dimethoxyphenol attaining maximum amounts 15 min after ME consumption and decreasing thereafter, while for (E)-coniferyl alcohol—the increase and decrease are more gradual. These results further demonstrate the ability of insect hemolymph to transport many diverse forms of bioactive molecules including attractant-derived sex pheromonal components. [Copyright &y& Elsevier]

Introduction of iodinated contrast into the intact colon is not expected to result in imaging-visible renal excretion of this contrast and is a phenomenon that has only rarely been described. We present a case in which such vicarious renal excretion was misinterpreted as a recto-vesical fistula which resulted in unnecessary delay in the patient’s management. [ABSTRACT FROM AUTHOR]

In order to investigate the metabolic poise of the elasmobranch rectal gland, we conducted two lines of experimentation. First, we examined the effects of feeding on plasma metabolites and enzyme activities from several metabolic pathways in several tissues of the dogfish shark, Squalus acanthias, after starvation and at 6, 20, 30 and 48 h post-feeding. We found a rapid and sustained ten-fold decrease in plasma β-hydroxybutyrate at 6 h and beyond compared with starved dogfish, suggesting an upregulation in the use of this substrate, a decrease in production, or both. Plasma acetoacetate levels remain unchanged, whereas there was a slight and transient decrease in plasma glucose levels at 6 h. Several enzymes showed a large increase in activity post-feeding, including β-hydroxybutyrate dehydrogenase in rectal gland and liver, and in rectal gland, isocitrate dehydrogenase, citrate synthase, lactate dehydrogenase, aspartate amino transferase, alanine amino transferase, glutamine synthetase and Na+/K+ ATPase. Also notable in these enzyme measurements was the overall high level of activity in the rectal gland in general. For example, activity of the Krebs' TCA cycle enzyme citrate synthase (over 30 U g-1) was similar to activities in muscle from other species of highly active fish. Surprisingly, lactate dehydrogenase activity in the gland was also high (over 150 U g-1), suggesting either an ability to produce lactate anaerobically or use lactate as an aerobic fuel. Given these interesting observations, in the second aspect of the study we examined the ability of several metabolic substrates (alone and in combination) to support chloride secretion by the rectal gland. Among the substrates tested at physiological concentrations (glucose, β-hydroxybutyrate, lactate, alanine, acetoacetate, and glutamate), only glucose could consistently maintain a viable preparation. Whereas β-hydroxybutyrate could enhance gland activity when presented in combination with glucose, surprisingly it could not sustain chloride secretion when used as a !one substrate. Our results are discussed in the context of the in vivo role of the gland and mechanisms of possible upregulation of enzyme activities. [ABSTRACT FROM AUTHOR]

The apical membrane is an important site of mercury toxicity in shark rectal gland tubular cells. We compared the effects of mercury and other thiol-reacting agents on shark CFTR (sCFTR) and human CFTR (hCFTR) chloride channels using two-electrode voltage clamping of cRNA microinjected Xenopus laevis oocytes. Chloride conductance was stimulated by perfusing with 10 μM forskolin (FOR) and 1 mM IBMX, and then thio-reactive species were added. In oocytes expressing sCFTR, FOR + IBMX mean stimulated Cl- conductance was inhibited 69% by 1 μM mercuric chloride and 78% by 5 μM mercuric chloride (IC50 of 0.8 μM). Despite comparable stimulation of conductance, hCFTR was insensitive to 1 μM HgCl2 and maximum inhibition was 15% at the highest concentration used (5 p.M). Subsequent e(xposure to glutathione (GSH) did not reverse the inhibition of sCFTR by mercury, but dithiothreitol (DTT) completely reversed this inhibition. Zinc (50–200 μM) also reversibly inhibited sCFTR (40–75%) but did not significantly inhibit hCFTR. Similar inhibition of sCFTR but not hCFTR was observed with an organic mercurial, p-chloromercuri-phenylsulfonic acid (pCMBS). The first membrane spanning domain (MSDI) of sCFTR contains two unique cysteines, Cl02 and C303. A chimeric construct replacing MSD1 of hCFTR with the corresponding sequence of sCFTR was highly sensitive to mercury. Site-specific mutations introducing the first but not the second shark unique cysteine in hCFTR MSD1 resulted in full sensitivity to mercury. These experiments demonstrate a profound difference in the sensitivity of shark vs. human CFTR to inhibition by three thiol-reactive substances, an effect that involves C102 in the shark orthologue. [ABSTRACT FROM AUTHOR]

A total of 179 lactations obtained on 71 multiparous sows [30 Creole (CR) and 41 Large White (LW)] between June 2001 and July 2004 were used to determine effects of breed (CR vs. LW) and season (hot vs. warm) in a tropical humid climate on performance during a 28-d lactation period. Mean daily ambient temperature was greater during the hot season than during the warm season (26.0 vs. 23.8°C), and relative humidity was similar in both seasons (85% on average). For both breeds, ADFI was reduced (-700 g/d, P < 0.01), sow BW loss was greater (17 vs. 12 kg, P < 0.01), and piglet growth was reduced (197 vs. 210 g/d, P < 0.05) during the hot vs. the warm season. At farrowing, LW sows were heavier (255 vs. 186 kg, P < 0.01) and had less backfat (21 vs. 40 mm, P < 0.01) than CR sows. The growth rate of CR piglets was lower than that of LW piglets (192 vs. 215 g/d, P < 0.01). A breed x season interaction was observed (P < 0.05) for ADFI and sow BW loss. During the hot season, the reduction of ADFI was more pronounced in LW than in CR sows (-910 vs. -470 gld). Regardless of the season, BW loss of CR sows remained constant (14.2 kg), whereas it increased during the hot season for LW sows (10 kg). The weaning-to-estrus and the weaning-to-conception intervals were not affected by breed or season and averaged 4.8 and 6.1 d, respectively. The rectal temperature was greater (0.3°C) during the hot season than during the warm season and greater in LW than in CR sows (39.1 vs. 38.8°C, P < 0.10). This study confirms the negative effect of hot season in a tropical humid climate on performance of lactating sows and that breed can have a significant effect on lactation performance. The results also suggest that CR sows are more heat tolerant than LW sows. [ABSTRACT FROM AUTHOR]

We assessed reproducibility of measurements of rectal compliance and sensation in health in studies conducted at two centres. We estimated samples size necessary to show clinically meaningful changes in future studies. We performed rectal barostat tests three times (day 1, day 1 after 4 h and 14–17 days later) in 34 healthy participants. We measured compliance and pressure thresholds for first sensation, urgency, discomfort and pain using ascending method of limits and symptom ratings for gas, urgency, discomfort and pain during four phasic distensions (12, 24, 36 and 48 mmHg) in random order. Results obtained at the two centres differed minimally. Reproducibility of sensory end points varies with type of sensation, pressure level and method of distension. Pressure threshold for pain and sensory ratings for non-painful sensations at 36 and 48 mmHg distension were most reproducible in the two centres. Sample size calculations suggested that crossover design is preferable in therapeutic trials: for each dose of medication tested, a sample of 21 should be sufficient to demonstrate 30% changes in all sensory thresholds and almost all sensory ratings. We conclude that reproducibility varies with sensation type, pressure level and distension method, but in a two-centre study, differences in observed results of sensation are minimal and pressure threshold for pain and sensory ratings at 36–48 mmHg of distension are reproducible. [ABSTRACT FROM AUTHOR]

In contrast to the modern cephalopods, the nautiloids use primarily the chemosensory sense to explore their environment. So far there have been few studies on sexual-selection processes in solitary-living nautiloid cephalopods, but it can be posited that conspecifics are also discovered by odour. In order to determine whether a special area of the rectum, the rectal gland, plays a role in the intraspecific communication processes of Nautilus pompilius, Y-maze experiments were performed. We tested the reaction of juvenile, early-adolescent male and female, and adult male N. pompilius to homogenates of the rectum of male and female conspecifics. As negative controls, homogenates of gills or mantle, or seawater were used. To check the set-up of the experiment, carrion was presented as a positive attractant. We demonstrated that the adult (mature) males significantly preferred the rectum homogenate containing the stimulus of females, whereas the homogenates from males and/or females had no influence on the behaviour of immature animals of both sexes. Our behavioural studies provide evidence that sexually mature male N. pompilius are attracted to females by excretions of the rectum. [ABSTRACT FROM AUTHOR]

This study examined the osmoregulatory status of the euryhaline elasmobranchCarcharhinus leucasacclimated to freshwater (FW) and seawater (SW). JuvenileC. leucascaptured in FW (3 mOsm l-1 kg-1) were acclimated to SW (980-1,000 mOsm l-1 kg-1) over 16 days. A FW group was maintained in captivity over a similar time period. In FW, bull sharks were hyper-osmotic regulators, having a plasma osmolarity of 595 mOsm l-1 kg-1. In SW, bull sharks had significantly higher plasma osmolarities (940 mOsm l-1 kg-1) than FW-acclimated animals and were slightly hypo-osmotic to the environment. Plasma Na+, Cl-, K+, Mg2+, Ca2+, urea and trimethylamine oxide (TMAO) concentrations were all significantly higher in bull sharks acclimated to SW, with urea and TMAO showing the greatest increase. Gill, rectal gland, kidney and intestinal tissue were taken from animals acclimated to FW and SW and analysed for maximal Na+/K+-ATPase activity. Na+/K+-ATPase activity in the gills and intestine was less than 1 mmol Pi mg-1 protein h-1 and there was no difference in activity between FW- and SW-acclimated animals. In contrast Na+/K+-ATPase activity in the rectal gland and kidney were significantly higher than gill and intestine and showed significant differences between the FW- and SW-acclimated groups. In FW and SW, rectal gland Na+/K+-ATPase activity was 5.6±0.8 and 9.2±0.6 mmol Pi mg-1 protein h-1, respectively. Na+/K+-ATPase activity in the kidney of FW and SW acclimated animals was 8.4±1.1 and 3.3±1.1 Pi mg-1 protein h-1, respectively. Thus juvenile bull sharks have the osmoregulatory plasticity to acclimate to SW; their preference for the upper reaches of rivers where salinity is low is therefore likely to be for predator avoidance and/or increased food abundance rather than because of a physiological constraint. [ABSTRACT FROM AUTHOR]

Aortoenteric fistula is defined as a communication between the aorta and any adjacent segment of the bowel. It may be primary or secondary. The former occurs de novo in patients with intestinal or vascular diseases, whereas secondary aortoenteric fistula is a rare and dreadful complication of aortic reconstruction with vascular prosthesis. We report a case of a 62-year-old man who presented to the emergency department with acute rectal bleeding. The patient had previous aortoiliac surgery with the utilization of an aorto-bifemoral vascular graft. Diagnosis of secondary aortoenteric fistula was made between the aortoiliac graft and sigmoid colon. After exploratory laparotomy, Hartmann’s procedure, excision of the graft, oversewing of the aortic stump, and axilobifemoral bypass were successfully performed. This study reports a rare type of secondary aortoenteric fistula to the left colon, and it describes an unusual and successful surgical treatment. [Copyright &y& Elsevier]

To compare, in a prospective study, bleeding (in three categories, i.e. haematuria, haematospermia and rectal) and consultations with the general practitioner (GP), after a six-, eight- or 12-core prostate biopsy, as data on whether taking more prostate core biopsies increases bleeding complications are not conclusive.Over a 5-year period, patients undergoing outpatient transrectal ultrasonography (TRUS)-guided prostate biopsy (six, eight or 12-core biopsy) completed a self-administered questionnaire. The prevalence and duration of the three bleeding complications and GP or hospital visits for a biopsy-related complication were assessed and compared for the 7 days after biopsy. The contribution of local anaesthetic (LA) injection to bleeding rates was also assessed.Of 1384 patients biopsied, 1000 were given questionnaires and 884 (88%) forms were returned. Of these, 760 were suitable for analysis (307 after six-core, 325 eight-core and 128 12-core biopsies); 351 patients were given LA before biopsy. The prevalence of bleeding complications (six-, eight- and 12-core, respectively) was: haematuria 44%, 41% and 39%; haematospermia 13%, 16% and 12%; and rectal bleeding 17%, 26% and 27%. Rectal bleeding was significantly more prevalent in the eight- and 12-core groups (P = 0.0037 and 0.019). The duration of bleeding was not significantly greater in any biopsy group. Subgroup analysis showed no significant difference in the prevalence and duration of rectal bleeding after LA. About 5% of patients in each group consulted their GP because of a complication and 2.4% consulted because of bleeding. Three men with major complications required hospitalization, of which only one was caused by bleeding.Only rectal bleeding was more prevalent after taking more than six cores, but the duration was no greater. Giving LA did not affect the rectal bleeding rate. With all strategies the major complication and hospitalization rate was very low. [ABSTRACT FROM AUTHOR]

Bull sharks (Carcharhinus leucas) were captured across a salinity gradient from freshwater (FW) to seawater (SW). Across all salinities, C. leucas were hyperosmotic to the environment. Plasma osmolarity in FW-captured animals (642±7 mosM) was significantly reduced compared to SW-captured animals (1067±21 mosM). In FW animals, sodium, chloride and urea were 208±3, 203±3 and 192±2 mmol l-1, respectively. Plasma sodium, chloride and urea in SW-captured C. leucas were 289±3, 296±6 and 370±10 mmol l-1, respectively. The increase in plasma osmolarity between FW and SW was not linear. Between FW (3 mosM) and 24‰ SW (676 mosM), plasma osmolarity increased by 22% or 0.92% per 1‰ rise in salinity. Between 24‰ and 33‰, plasma osmolarity increased by 33% or 4.7% per 1‰ rise in salinity, largely due to a sharp increase in plasma urea between 28‰ and 33‰. C. leucas moving between FW and SW appear to be faced with three major osmoregulatory challenges, these occur between 0–10‰, 11–20‰ and 21–33‰. A comparison between C. leucas captured in FW and estuarine environments (20–28‰) in the Brisbane River revealed no difference in the mass of rectal glands between these animals. However, a comparison of rectal gland mass between FW animals captured in the Brisbane River and Rio San Juan/Lake Nicaragua showed that animals in the latter system had a significantly smaller rectal gland mass at a given length than animals in the Brisbane River. The physiological challenges and mechanisms required for C. leucas moving between FW and SW, as well as the ecological implications of these data are discussed. [Copyright &y& Elsevier]

The article reports that the American Society of Colon and Rectal Surgeons celebrates its 104th year with this meeting and is a unique group, numbering more than 2,300 members worldwide. It is a very different group from others with which the author have been associated, likely because of the warm and affable personalities of those who have chosen a career in colon and rectal surgery. Newcomers to the society meetings are immediately made to feel welcome, and long-term friendships are easily formed.

: PurposeConformal radiotherapy (RT) has allowed radiation dose escalation to improve the outcome of prostate cancer. With higher doses, concern exists that rectal injury may increase. This study analyzed the utility and limitations of the widely used Lyman-Kutcher- Burman (LKB) normal tissue complication probability model in projecting the hazards of rectal complication with high-dose RT.: Methods and materialsA total of 128 patients were included in this study. These patients were treated with three-dimensional conformal RT alone at the University of Texas M.D. Anderson Cancer Center between 1992 and 1999. Patients were treated to 46 Gy with a four-field box technique followed by a six-field arrangement to boost the total dose to 78 Gy. All doses were delivered at 2 Gy/fraction to the isocenter. The minimal follow-up was 2 years. The end point for analysis was Grade 2 or worse rectal bleeding by 2 years. The LKB model was fitted to the data using the maximal likelihood method.: ResultsOf the 128 patients, 29 experienced Grade 2 or worse rectal bleeding by 2 years. For the entire cohort, the parameters obtained from the fit of the LKB model were as follows: the volume factor was n = 3.91 (95% confidence interval [CI] 0.031 to ∞), dose associated with 50% chance of complication for uniform whole rectal irradiation [TD50(1)] was 53.6 Gy (95% CI 50.0–75.1), and a determinant of the steepness of the dose–response curve, (m), was 0.156 (95% CI 0.036–0.271). A statistically significant difference was found in the rate of postradiation rectal bleeding in patients with hemorrhoids vs. those without hemorrhoids. The parameters obtained for the patients without hemorrhoids were as follows: n = 0.746 (95% CI 0.026 to ∞), TD50(1) 56.7 Gy (95% CI 49.9–75.2), and m 0.092 (95% CI 0.019–0.189).: ConclusionOur analysis suggests a dose response for rectal bleeding probability along with a volume effect. We found that the LKB model might have limited utility in determining a large volume effect. We further suggest that LKB model should be used with caution in clinical practice. [Copyright &y& Elsevier]

Visceral hypersensitivity has been shown to be present in irritable bowel syndrome (IBS). The current study sought to compare the characteristics of visceral perception thresholds after rectal thermal and pressure stimuli between IBS patients and healthy subjects. A total of 46 patients with IBS were diagnosed using Rome II criteria. Thirteen healthy individuals participated in the study. Rectal visceral perception thresholds were examined in patients with IBS and in normal controls after thermal and pressure stimuli. Subjects were asked to report the sensation type, location, and spread. Compared with healthy subjects, IBS patients demonstrated significantly initially lower perception thresholds and defecation thresholds to rectal thermal and pressure stimuli, particularly in patients with diarrhea-predominant IBS. Ice stimuli on the abdominal wall had varied effects on symptoms in patients with IBS and did not affect perception thresholds. Visceral perception thresholds were decreased significantly after rectal thermal and pressure stimuli in patients with IBS. Visceral hypersensitivity may be one of the important pathogenic mechanisms in IBS. [ABSTRACT FROM AUTHOR]

Since the landmark contributions of Homer Smith and co-workers in the 1930s there has been a considerable advance in our knowledge regarding the osmoregulatory strategy of elasmobranch fish. Smith recognised that urea was retained in the body fluids as part of the ‘osmoregulatory ballast’ of elasmobranch fish so that body fluid osmolality is raised to a level that is iso- or slightly hyper-osmotic to that of the surrounding medium. From studies at that time he also postulated that many marine dwelling elasmobranchs were not capable of adaptation to dilute environments. However, more recent investigations have demonstrated that, at least in some species, this may not be the case. Gradual acclimation of marine dwelling elasmobranchs to varying environmental salinities under laboratory conditions has demonstrated that these fish do have the capacity to acclimate to changes in salinity through independent regulation of Na+, Cl− and urea levels. This suggests that many of the presumed stenohaline marine elasmobranchs could in fact be described as partially euryhaline. The contributions of Thomas Thorson in the 1970s demonstrated the osmoregulatory strategy of a fully euryhaline elasmobranch, the bull shark, Carcharhinus leucas, and more recent investigations have examined the mechanisms behind this strategy in the euryhaline elasmobranch, Dasyatis sabina. Both partially euryhaline and fully euryhaline species utilise the same physiological processes to control urea, Na+ and Cl− levels within the body fluids. The role of the gills, kidney, liver, rectal gland and drinking process is discussed in relation to the endocrine control of urea, Na+ and Cl− levels as elasmobranchs acclimate to different environmental salinities. [Copyright &y& Elsevier]

Describes the complete coding sequence, expression, and cellular localization of PLMS in the rectal gland of the shark Squalus acanthias. Amino acids in the mature protein; Immunogold labeling; Identification of the FXYD domain-containing protein in Na,K-ATPase membrane preparations from shark rectal glands.

: BackgroundFor advanced degree of hemorrhoids with prolapse of the rectal mucosa, the choice is hemorrhoidectomy, which could be open, close, diathermy, Laser, or stapled one. As an effective alternative to this, in situ radio-frequency ablation of the pile mass has been found to be quite efficacious with many added advantages over the conventional hemorrhoidectomy procedures in practice.: Materials and methodsThis study included 50 patients (34 males and 16 females) treated at Gupta Nursing Home, Laxminagar, Nagpur, India, with the above technique from April 2000 to March 2001 and each case followed up over a period of 12 months.: ResultsIn first 4 weeks of the procedure, 14% of patients complained of bleeding, whereas all of the patients had some amount of pain. Eleven (22%) patients had serosanguinous discharge, but in none of them was there any incontinence or prolapse. All of the patients resumed their routine within 1 week of the procedure. A subsequent follow-up of the patients at an interval of 12 weeks and 12 months showed significant relief in all of the above early postoperative symptoms. During follow-up at the end of 1 year, 7 patients were found to have skin tag formation. However, complications like anal stenosis or stricture or incontinence was not found in any of the patients.: ConclusionFor advanced degree of piles with prolapse as the main symptom, in situ radio-frequency ablation can be a better choice to various types of hemorrhoidectomy in the sense that the hospital stay is minimized, recurrence is rare, and return to work is faster. The results are more assuring when compared with conventional hemorrhoidectomy. The technique fits into the parameters for being called the gold standard procedure.Except the radio-frequency unit, the procedure needs no specialized instrument. It can be performed in any routine surgical setup. [Copyright &y& Elsevier]

: ObjectivesThe association between celiac disease and insulin dependent diabetes mellitus (IDDM) is well established. Rectal gluten challenge has been used in patients with celiac disease and in first degree relatives as a tool to assess the mucosal immune response to gluten. The aim of this study was to assess the mucosal immune response to gluten in IDDM children by rectal gluten challenge.: MethodsRectal biopsy specimens were obtained from 19 children with IDDM before and 6 h after rectal challenge with 2 g of a peptic tryptic digest of gliadin. A total of 16 treated celiac patients and 10 control subjects were also investigated. Epithelium and lamina propria CD3+ and γδ+ lymphocytes were counted with reference to a standard reference area of muscolaris mucosae (104 μm2).: ResultsAfter a local instillation of gliadin, a significant (>mean + 1 SD) percentage increment of lamina propria and epithelium CD3+ and of lamina propria and epithelium γδ+ lymphocytes was observed in five IDDM children, as compared to 11 and 13 celiac patients and one and two controls, respectively. A discriminant analysis allowed correct classification of 100% of patients with celiac disease and controls. The same analysis classified four of 19 IDDM children in the group of celiac patients. The positivity was associated with normal serology (antigliadin antibody, antiendomysial antibody, and antitissue transglutaminase antibodies) and a morphologically normal jejunal mucosa. All four patients had HLA-DQ alleles associated with celiac disease.: ConclusionsApproximately 20% of IDDM children react to rectal instillation of gliadin. Long term follow-up is necessary to establish whether these subjects are at increased risk for developing celiac disease. [Copyright &y& Elsevier]

PURPOSE The management of complex perianal fistulas with endorectal advancement flap is aimed at avoiding the risk of sphincter injury associated with traditional surgical methods. Long-term follow-up is required to assess the recurrence and continence outcomes of this procedure. The aim of this study was to review our experience with endorectal advancement flap in the treatment of complex perianal fistulas and to define the predictors of successful healing.METHODS A retrospective chart review of all patients who underwent endorectal advancement flap for complex perianal fistulas between 1988 and 2000 was performed. Follow-up was established by telephone interview.RESULTS One hundred six consecutive endorectal advancement flap procedures were performed on 94 patients (94.4 percent). There were 56 females (59.6 percent). Mean age was 41.6 (range, 18-76) years. Cryptoglandular disease was the most common cause of fistula (n = 41, 43.6 percent), followed by Crohn''s disease (n = 28, 29.8 percent). At a mean follow-up of 40.3 (range, 1-149) months, the procedure was successful in 56 (59.6 percent) of 94 patients. Twelve patients underwent repeat surgery with the same technique because of initial failure, 8 of whom eventually healed. Crohn''s disease was associated with a significantly higher recurrence rate (57.1 percent) when compared with fistulas in patients without Crohn''s disease (33.3 percent, < 0.04). Prior attempts at repair of the fistula were not associated with less favorable outcome of the procedure ( = 0.5). Recurrence was not associated with the type of fistula, origin, preoperative steroid use, postoperative bowel confinement, use of postoperative antibiotics, or creation of a diverting stoma. The median time to recurrence was 8 (range, 1-156) weeks; there was no postoperative mortality. Two patients had postoperative bleeding, one requiring resuture of the flap on the first postoperative day. Recurrences were observed in 15.7 percent of the patients 3 or more years after the repair. In 8 patients (9 percent), continence deteriorated after the endorectal advancement flap, a more common finding in patients who had undergone previous surgical repairs ( < 0.02).CONCLUSION The success rate of endorectal advancement flap for complex perianal fistulas is modest. Failure is mainly correlated with the presence of Crohn''s disease. [ABSTRACT FROM AUTHOR]

The salt gland of the spiny dogfish, Squalus acanthias, can be stimulated to secrete chloride by two different endogenous peptides: cardiac natriuretic peptide (CNP) and the neurotransmitter, vasoactive intestinal peptide (VIP). We examined the role of the actin cytoskeleton and of myosin light chains in this process by perfusing isolated rectal glands with and without an inhibitor of actin filament organization (cytochalasin D) and an inhibitor of myosin light chain kinase (ML-7). Cytochalasin D, 10–6 M, reduced secretion stimulated by a 1-min bolus of CNP (5×10–7 M) by 50–60%. In the presence of 10–2 M procaine (which blocks neural release of VIP), cytochalasin D completely prevented CNP stimulation. In contrast, cytochalasin D did not inhibit stimulation of the rectal gland by VIP or by forskolin. Similarly, 5×10–6M ML-7 almost completely inhibited direct stimulation of rectal gland secretion by CNP, but did not alter chloride secretion induced by VIP or forskolin. Finally, the average time between hormonal injection and activation of secretion was 2 min longer for CNP than for VIP, consistent with the hypothesis that a contractile cellular function involving the cytoskeleton is important in CNP-induced chloride secretion, but less so when secretion is stimulated by VIP. [ABSTRACT FROM AUTHOR]

The present studies were carried out with the aims to determine the cDNA sequence for cyclooxygenase (COX) in an elasmobranch species and to study its role in regulation of chloride secretion in the perfused shark rectal gland (SRG). With the use of long primers (43 bp) derived from regions of homology between zebrafish and rainbow trout COX-2 genes, a 600-bp product was amplified from SRG and was found to be almost equally homologous to mammafian COX-1 and COX-2 (65%). The full-length cDNA sequence was obtained by 5′-RACE and by analyzing an EST clone generated by the EST Project of the Mt. Desert Island Biological Laboratory Marine DNA Sequencing Center. The longest open reading frame encodes a 593-amino acid protein that has 68 and 64% homology to mammalian COX-1 and COX-2, respectively. The gene and its protein product is designated as shark COX (sCOX). The key residues in the active site (Try[sup 385], His[sup 388], and Ser[sup 30]°) are conserved between the shark and mammalian COX. sCOX contains Val[sup 523] that has been shown to be a key residue determining the sensitivity to COX-2-specific inhibitors including NS-398. The mRNA of sCOX, detected by RT-PCR, was found in all tissues tested, including rectal gland, kidney, spleen, gill, liver, brain, and heart, but not in fin. In the perfused SRG, vasoactive intestinal peptide (VIP) at 5 nM induced rapid and marked Cl[sup -] secretion (basal: <250 µeq·h[sup -1]·g[sup -1]; peak response: 3,108 ± 479 µeq·h[sup -1]·g[sup -1]). In the presence of 50 µM NS-398, both the peak response (2,131 ± 307 µeq·h[sup -1]·g[sup 1]) and the sustained response to VIP were significantly reduced. When NS-398 was removed, there was a prompt recovery of chloride secretion to control values. In conclusion, we have cloned the first COX in an elasmobranch species (sCOX) and shown that sCOX inhibition suppresses VIPstimulated chloride... [ABSTRACT FROM AUTHOR]

Assesses calcium sensitivity in the shark, Squalus acanthias. Rectal gland artery (RGA) response to extracellular calcium; Calcium signaling mechanisms of calcium sensing receptor; RGA response to norepinephrine.

Chloride secretion rates of rectal glands taken from the European lesser-spotted dogfishScyliorhinus canicula adapting to 70% and 120% sea water (SW) were significantly greater and less than, respectively, those in the control 100% SW group. C-type natriuretic peptide (CNP) significantly increased chloride secretion rates above basal values in 100% SW although angiotenisn II (ANG II) had no effect. Perfusion of the secretory epithelia in rectal glands from 70% SW lesser-spotted dogfish was significantly higher than in rectal glands from 100% and 120% SW lesser-spotted dogfish. Perfusion of rectal glands with ANG II had no effect on perfusion of the secretory epithelia, although CNP perfusion induced significantly greater perfusion of the secretory epithelia than all other treatments. It remains to be determined if a reduction in environmental salinity induces an increase in plasma concentration of CNP and hence an increase in rectal gland activity. Copyright 2002 The Fisheries Society of the British Isles. Published by Elsevier Science Ltd. All rights reserved. [Copyright &y& Elsevier]

In marine teleost fishes, the gill mitochondria-rich cells (MRCs) are responsible for NaCl elimination; however, in elasmobranch fishes, the specialized rectal gland is considered to be the most important site for salt secretion. The role of the gills in elasmobranch ion regulation, although clearly shown to be secondary, is not well characterized. In the present study, we investigated some morphological properties of the branchial MRCs and the localization, and activity of the important ionoregulatory enzyme Na+/K+-ATPase, under control conditions and following rectal gland removal (1 month) in the spiny dogfish, Squalus acanthias. A clear correlation can be made between MRC numbers and the levels of Na+/K+-ATPase activity in crude gill homogenates (r2=−0.69). Strong Na+/K+-ATPase immunoreactivity is also clearly associated with the basolateral membrane of these MRCs. In addition, the dogfish were able to maintain ionic balance after rectal gland removal. These results all suggest a possible role of the dogfish gill in salt secretion. MRCs were, however, unresponsive to rectal gland removal in terms of changes in number, fine structure and Na+/K+-ATPase activity, as might be expected if they were compensating for the loss of salt secretion by the rectal gland. Thus, the specific role that these MRCs play in ion regulation in the dogfish remains to be determined [Copyright &y& Elsevier]

Rectal stimulation under normal or pathological conditions evokes numerous sensations. Previous studies have examined rectal stimulation-evoked pain and urge to defecate, but discrepancies in the findings remain because of the different methodologies used in each study and the reporting of sensations only at the end of or after the applied stimuli. Therefore, we conducted a psychophysical study of various aspects of rectal sensation in normal subjects using a variety of distension stimuli and continuous on-line rating of sensation. Ten normal healthy subjects (eight female and two male) were given rectal distension stimuli delivered by a computer-driven barostat. For some experiments, sensation was continuously monitored and rated on a visual analog scale. Subjects first underwent an ascending series of phasic (30 s) distensions to determine how urge, unpleasantness, and pain intensity varied and interrelated as rectal volume and pressure changed. A second series of distensions examined rectal physiology and perception during short phasic (30 s) or long (300 s) distensions at pressures that elicit either moderate urge or moderate pain and while continuously rating these sensations. The McGill Pain Questionnaire was used to assess the multidimensional aspects of rectal pain with each type of distension. The results of the ascending series revealed significant relationships between sensations as pressure and volume increased. The ratings of urge were double that of pain and unpleasantness, whereas unpleasantness and pain ratings were comparable. Isobaric phasic and tonic distensions were associated with an increase in volume (i.e. accommodation) with time. The magnitude of urge with repetitive short isobaric (30 s) distensions was overall not related to the slight increase in rectal volume, while phasic distensions at moderate pain intensity revealed a significant overall relationship between rectal volume and both unpleasantness and pain intensity. Long isobaric distensions evoked sensations that varied over time despite progressive increases in volume, but less variation in sensation was observed during short phasic distensions which also demonstrated a similar increase in rectal volume. Differences in temporal characteristics of sensations evoked by low-pressure distensions eliciting moderate urge versus high-pressure distensions eliciting moderate pain were illustrated by a significantly longer delay to the diminution of non-painful urge versus pain. Therefore, we conclude (1) Differences in the discrimination and the temporal characteristics of urge at subpainful rectal pressures and of pain at noxious pressures suggest that noxious and non-noxious stimuli are processed differently. (2) The overall unpleasantness and pain correlate with rectal volume during accommodation. However, instantaneous evoked sensations can vary independent of volume changes during constant pressure distension. (3) The reported sensation-related responses to tension and stretch will likely be different depending on the degree of accommodation that is occurring. Moreover, the peripheral receptor mechanisms which contribute to controlling this accommodation will also affect the perception of rectal stimuli. (4) Continuous ratings of rectal sensations are valuable in investigating rectal physiology and the multidimensional nature of rectal symptoms. [Copyright &y& Elsevier]

The effects of acute and subchronic exposure to mercury on the Cl− current (ICl) were investigated in cultured shark rectal gland (SRG) cells. The effects of intracellular accumulation of mercury on cytochrome P450 (P450) were also assessed. Bath perfusion of a cocktail solution containing forskolin, 1-isobutyl-3-methylxanthine, and 8-bromoadenosine monophosphate enhanced ICl. Addition of 10 μM HgCl2 significantly inhibited the cAMP-activated ICl (p < 0.05, n = 11). Intracellular dialysis with ATPγS did not prevent the inhibitory effect of mercury on ICl. In contrast, incubation of SRG cells with 10 μM HgCl2 for 48 hrs markedly increased ICl (p < 0.01, n = 12). Dephosphorylation of the channel by intracellular dialysis with phosphatase I and II abolished the mercury-incubated increase in ICl. The P450-mediated metabolite of arachidonic acid, 11,12-epoxyeicosatrienoic acid (11,12-EET), significantly increased ICl. However, application of 11,12-dihydroxyeicosatrienoic acid (11,12-DHT) did not alter ICl. Mercury incubation for 48 hrs did not alter the protein expression of Cl− channels, but caused an induction of CYP1A1 in cultured SRG cells. In addition, co-incubation of SRG cells with mercury and the P450 inhibitor clotrimazole prevented the mercury-incubated increase in ICl. Our results demonstrate that acute and subchronic application of mercury has opposing effects on ICl in cultured SRG cells. The acute effect of mercury on ICl may result from mercury blockade of Cl− channels. The subchronic effect of mercury on ICl may be due to an induction of P450 CYP1A1 and its mediated metabolites, but not due to an over-expression of Cl− channels. [Copyright &y& Elsevier]

cDNA fragments of both the α- and β-subunits of the Na, K-ATPase and a cDNA fragment of the secretory form of Na–K–Cl cotransporter from the European dogfish (Scyliorhinus canicula) were amplified and cloned using degenerate primers in RT-PCR. These clones were used along with a sCFTR cDNA from the related dogfish shark, Squalus acanthias to characterise the expression of mRNAs for these ion transporters in the dogfish rectal gland subsequent to an acute feeding episode. Following a single feeding event where starved dogfish were fed squid portions (20 g squid/kg fish), there was a delayed and transient 40-fold increase in the activity of Na, K-ATPase in crude rectal gland homogenates. Increases in enzyme activity were apparent 3 h after the feeding event and peaked at 9 h before returning to control values within 24 h. These increases in activity were accompanied by small and transient decreases in plasma sodium and chloride concentrations lasting up to 3 days. Significant increases in the expression of mRNAs for α- and β-subunits of the Na, K-ATPase, the Na–K–Cl cotransporter and CFTR chloride channel were detected but not until 1–2 days after the feeding event. It is concluded that the transient increase in Na, K-ATPase activity is not attributable to increases in the abundance of α- and β-subunit mRNAs but must be associated with some, as yet unknown, post-transcriptional activation mechanism. [Copyright &y& Elsevier]

KCNQ1 (KVLQT1) K+ channels play an important role during electrolyte secretion in airways and colon. KCNQ1 was cloned recently from NaCl-secreting shark rectal glands. Here we study the properties and regulation of the cloned sKVLQT1 expressed in Xenopus oocytes and Chinese hamster ovary (CHO) cells and compare the results with those obtained from in vitro perfused rectal gland tubules (RGT). The expression of sKCNQ1 induced voltage-dependent, delayed activated K+ currents, which were augmented by an increase in intracellular cAMP and Ca2+. The chromanol derivatives 293B and 526B potently inhibited sKCNQ1 expressed in oocytes and CHO cells, but had little effect on RGT electrolyte transport. Short-circuit currents in RGT were activated by alkalinization and were decreased by acidification. In CHO cells an alkaline pH activated and an acidic pH inhibited 293B-sensitive KCNQ1 currents. Noise analysis of the cell-attached basolateral membrane of RGT indicated the presence of low-conductance (<3 pS) K+ channels, in parallel with other K+ channels. sKCNQ1 generated similar small-conductance K+ channels upon expression in CHO cells and Xenopus oocytes. The results suggest the presence of low-conductance KCNQ1 K+ channels in RGT, which are probably regulated by changes in intracellular cAMP, Ca2+ and pH. [ABSTRACT FROM AUTHOR]

A comprehensive anatomical study was undertaken to examine the rectal salt gland in the Port Jackson shark, Heterodontus portusjacksoni, a shark known to invade estuarine environments. The microstructure and vascular organisation of the rectal salt gland was investigated using histological observation and scanning electron microscopy of vascular corrosion casts. Cellular specialisation was observed in the lining of the central lumen of this gland. This may indicate that there is some modification of the principal product of the gland prior to its secretion. The rectal salt gland has a complex structure related to its function. Contrary to previous reports, the flow in secretory tubules is in the opposite direction to that of the capillaries and thus constitutes a counter-current arrangement. The similarity in the organisation of the counter-current and lobulate arrangement of salt-secreting glands through phylogenetically diverse organisms, such as sharks and birds, suggests that this arrangement is important in achieving efficient salt secretion.Copyright © 2001 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Enzymatically inactive, delipidated Na,K-ATPase from dogfish rectal glands was titrated with dioleoylphosphatidylcholine and with dioleoylphosphatidylethanolamine. The process of relipidation has the following characteristic properties. Enzymatic activities reappear independently of each other: first the phosphatase, then the ATPase. The properties of the phosphatase regenerated depend on the ratio of lipid/protein used; the ATPase seems to be independent of this ratio. The simplest model that is consistent with the above results and with the shapes of the titration curves, has the following requirements. Firstly, the enzyme is composed of two subunits that, as far as lipid binding is concerned, are identical and independent of each other. Secondly, lipid adds onto the enzyme as preformed clumps of 25 molecules of phosphatidylcholine or 18 molecules of phosphatidylethanolamine. Thirdly, each subunit binds two clumps of lipid, and binding shows positive cooperativity. Fourthly, when either subunit becomes saturated with lipid, the enzyme exhibits one form of phosphatase. Fifthly, when both subunits are saturated with lipid, the enzyme exhibits a second form of phosphatase and ATPase. The data and their analysis according to this model lead to the suggestion that Na,K-ATPase is a functional dimer, the interaction between subunits being influenced by the Na+ and K+ concentrations in the medium: K+ favouring the functional independence of the subunits and Na+ favouring their functional interaction. [ABSTRACT FROM AUTHOR]

A membrane fraction, rich in basal-lateral plasma membranes, was prepared from the rectal gland of the spiny dogfish, Squalus acanthias, and the uptake ofNa into the plasma membrane vesicles was investigated by a rapid filtration technique. Sodium uptake was greatest in the presence of a chloride gradient directed into the vesicles; it was strikingly reduced when chloride was replaced with nitrate and was even slower with gluconate. If the membrane vesicles were pre-equilibrated with potassium chloride or potassium nitrate plus valinomycin, to minimize any electrical driving forces on sodium movement, the uptake of sodium was still greatest in the presence of chloride and remarkably decreased in the presence of nitrate. Furosemide, 10 and 10 M, decreased sodium uptake into the vesicles in a dose dependent manner only in the presence of chloride. Furthermore, saturation of sodium uptake by increasing sodium chloride concentrations was observed. The above results provide direct evidence for a coupling of sodium and chloride fluxes across the plasma membrane of the rectal gland via a cotransport system sensitive to furosemide. They support the hypothesis that chloride secretion of the rectal gland is a secondary active transport and is driven by the sodium gradient across the basal-lateral membranes of the cell. [ABSTRACT FROM AUTHOR]

The foregut, stomach, caecum, midgut, and rectum of the digestive tract of Nautilus pompilius L.were investigated with ultrastructural and enzyme-cytological methods. Three different cell types were identified within the lamina epithelialis mucosae: main cells, goblet cells, and cells with secretory granules. The main cell type is the epithelial cell with microvilli, a basal nucleus surrounded by dictyosomes, rough endoplasmic reticulum, mitochondria, and electron-dense granules identified as lysosomes in the apical part of the cell. In the caecum this cell type contains endosymbiotic bacteria. The presence of endocytotic vesicles and the storage of lipids in the caecum indicate that this organ is involved in the process of absorption. In the caecum and the longitudinal groove of the rectum the main cells are, in addition, ciliated, facilitating the transport of food particles and faeces. Two types of goblet cells are found in all organs except in the stomach, forming a gliding path for food particles and protecting the epithelium. In the foregut and rectum, cells with electron-dense granules were recognized as the third type. The conspicuous secretory cells of the rectum represent a delimited rectal gland; its possible biological function is discussed. The tunica muscularis in all organs of the digestive tract consists of obliquely striated muscle cells innervated by axons containing transparent, osmiophilic and dense-cored vesicles. Positive reactions for acid and alkaline phosphatase, monoamine oxidase, β-glucuronidase, and trypsin- and chymotrypsin-like enzymes are localized in the lamina epithelialis mucosae. [ABSTRACT FROM AUTHOR]

Anatomical and histological studies of the alimentary organs of sixteen reduviids, with diverse food habits indicate structural variations. The terminal part of the tubular second midgut of these predaceous insects has a permanent sac-like region with distinct histology, concerned with absorption of digested food. In addition, the digestive system is characterised by a reduced pylorus with pyloric-intestinal and pyloric-rectal valves, surrounded by flask-shaped ampullae of the four malpighian tubules. The ampullary cells with their filamentous apices and with fibrillar cytoplasmic processes are concerned with. water absorption. Commonly in all these terrestrial insects, the anterior end of the rectum also bears a well-developed, inverted cup-like rectal gland, the cells of which also absorb water from the excreta stored in the impermeable, intima lined rectum. Members of Ectrichodiinae show simple ampullary cells and a unique rectum, reported for the first time among reduviids with scattered dome-shaped glandular cells as found in Homoptera and in some phytophagous Heteroptera. The simple nature of the alimentary organs indicates its primitive organization within the reduviid subfamilies. [ABSTRACT FROM AUTHOR]

The present study examines the influences of pH and Ca and several putative inhibitors on the basolateral K channel of the rectal gland of Squalus acanthias. Excised membrane patches were examined using the patch clamp technique. It is shown that reduction of the calcium activity on the cytosolic side to less than 10 mol/l has no detectable inhibitory effect on this channel. Conversely, increase in calcium activity to some 10 mol/l reduced the activity of this channel. Variations in cytosolic pH had only a moderate effect on the current amplitude: alkalosis by one pH unit increased and acidosis reduced the single current amplitude by some 15%. Several inhibitors were tested in excised patches when added to the cytosolic side. Ba (≈5·10 mol/l), quinine (≈10 mol/l), quinidine (≈10 mol/l), lidocaine (≈1 mmol/l), tetraethylammonium (≈10 mmol/l), Cs (≈10 mmol/l), and Rb (≈20 mmol/l) all blocked this K channel reversibly. We conclude that the basolateral K channel of the rectal gland is distinct from other epithelial K channels inasmuch as it is not stimulated by Ca directly, but that it is qualitatively similar to many other known K channels with respect to its sensitivity towards blockers. [ABSTRACT FROM AUTHOR]

The rectal gland of the dogfish ( Squalus acanthias) secretes chloride via a chloride channel present in the apical cell membrane. Using the patch clamp technique in isolated perfused rectal gland tubules [7], two types of chloride channels are demonstrable in the apical membrane of cyclic AMP treated tubule segments. A small channel of about 11 pS and another channel of 40-50 pS are present. The small channel is described in the succeeding report. With NaCl on both sides (excised patches) the current amplitude of the larger channel is an almost linear function of the voltage (±50 mV). However, the open probability of this channel is grossly reduced at negative clamp potentials (corresponding to cell hyperpolarization). Therefore, the macroscopic Cl current through this channel is reduced with hyperpolarization on the cytosolic side. An analysis of time constants of this channel reveals that at depolarized voltages two open and two closed time constants of about 1 ms and of about 10 ms, respectively, are demonstrable. With hyperpolarized voltages the larger open state time constant is reduced significantly. This type of chloride channel is blocked reversibly by diphenylamine-2-carboxylate (10 mol/l) and by 5-nitro-2-(3-phenylpropylamino)-benzoate (10 mol/l). The channel is selective for Cl over Na and K as well as over Br. It is, however, permeable for NO. Since this channel is very rare or absent in nonstimulated rectal gland tubules, it is very likely that this type of channel is responsible for hormone and cAMP dependent chloride secretion in this organ. [ABSTRACT FROM AUTHOR]

Besides the 'larger' Cl channel with a single channel conductance of about 45 pS, a 'small' channel was observed in the luminal membrane of the dogfish rectal gland [9]. In cell excised (inside out) patches with NaCl solution on both sides, the latter channel had a single channel conductance of 11±1 pS ( n=21), and its current-voltage relationship was linear in the voltage range+90 to −90 mV. The open state probability increased moderately with negative clamp potentials. Ionic replacement studies revealed a high selectivity of Cl over gluconate, sulfate, and iodide, whereas bromide was permeable to some extent. Also the channel is impermeable for Na. The Cl channel blocker 5-nitro-2-(3-phenylpropylamino)-benzoate did not affect this 'small' conductance Cl channel. It can be concluded that the luminal membrane of stimulated rectal gland cells possesses two types of Cl channels, which differ markedly in their characteristics. [ABSTRACT FROM AUTHOR]

Previous studies in isolated, in vitro perfused rectal gland tubules (RGT) have revealed that the basolateral membrane possesses a K conductive pathway. In the present study, we have utilized the patch clamp technique in RGT segments to characterize this pathway. The basolateral membrane was approached with patch pipettes at the open end of in vitro perfused segments [5]. Recordings were obtained in cell-attached as well as in excised inside-out patches. In cell-attached patches with the pipette filled with a KCl solution (274 mmol/l) and the bath containing NaCl shark Ringer (275 mmol/l), inward K currents (from pipette into cell) with a mean slope conductance of 123±26 pS ( n=3) were observed. We were unable to generate outward K currents at high depolarizing (cell more positive) clamp voltages. This indicates inward rectification of this channel. To examine the rectification properties further, excised (inside out) patches were exposed to K concentration gradients, directed out of, as well as into the pipette. With NaCl in the pipette and KCl in the bath, K outward currents were observed. The current-voltage (IV) relation revealed Goldman-type rectification, with a mean single channel conductance of 185±28 pS ( n=7) at high positive voltages (linear range of the IV curve). The single-channel permeability coefficient for K was 0.26±0.04 ·10 cm/s ( n=7). In the reversed experiment (pipette KCl, bath NaCl), inward currents of similar kinetics and amplitude were obtained. The single channel conductance was 146±21 pS ( n=7) at high negative voltages (linear range of the IV curve). The single channel permeability coefficient for K was 0.21±0.03·10 cm/s ( n=7). We were not able to reverse the currents in any of these experiments, indicating that this channel is highly selective for K over Na. In all three series of experiments, the kinetic appearance of the channels was similar. Bursts of activity were followed by interburst pauses. The open state was described by a single time constant of 3.0±0.2 ms, whereas the closed state was described by two time constants of 0.7±0.2 ms and 2.8±0.5 ms ( n=8). It can be concluded that these channels permit K inward and outward currents. They are probably the equivalent of the basolateral K conductance as observed in a previous study [12]. Under physiological conditions a single channel conductance of some 20 pS is predicted from the present data. In cell-attached patches, with a high K concentration in the pipette, the channel behaves as an inward rectifier. [ABSTRACT FROM AUTHOR]

Rectal gland tubule (RGT) segements of the spiny dogfish ( Squalus acanthias) were perfused in vitro. The effects of inhibitors of known mode of action on transepithelial PD (PD resistance (R), the PD across the basolateral membrane (PD), the fractional resistance of this membrane (FR), and intracellular activities of Na, Cl, K ( a) were examined. Furosemide (5·10 mol·l) reduced PD from −12±0.7 to −2.3±0.2 mV ( n=63), hyperpolarized PD from −71±1.3 to −79±0.9 mV ( n=59), FR decreased from 0.2±0.03 to 0.13±0.01 ( n=21), a fell from 38±4 to 11±2 mmol·l ( n=14), a fell from 37±4 to 17±2 mmol·l ( n=12) and a was constant [113±14 vs. 117±15 mmol·l ( n=6)]. Furosemide exerted its effects within some 20-40 s. Its action was completely reversible. Analysis of the time courses revealed that the furosemide induced initial fall in a was approximately twice as rapid when compared to that of a. Ba 0.5 mmol·l (bath) reduced PD from −7.4±1.2 to −4.1±0.6 mV ( n=24), increased R from 18±2 to 22±2.5, Ωcm ( n=14). PD depolarized from −75±2 to −48±2 mV ( n=42), FR increased from 0.2±0.02 to 0.34±0.04 ( n=14) and a increased from 143±28 to 188±40 mmol·l ( n=4). Ouabain (50·10 mol·l, bath) reduced PD from −12±2 to −3±0.5 mV ( n=9), R increased from 18±3 to 21±3 Ωcm ( n=5), PD depolarized from −67±4 to −26±3 mV ( n=14), FR increased from 0.23±0.04 to 0.45±0.05 ( n=6), a fell only slightly from 135±15 to 112±30 mmol·l ( n=4), but a increased from 35±12 to 111±37 mmol·l ( n=3). These effects of ouabain were slow when compared to those exerted by furosemide or Ba. The ouabain effects on PD and PD were completely prevented if furosemide was applied first. Amiloride (≤10 mol·l, both sides), and anthracene-9-carboxylate (≤10 mol·l, lumen) were devoid of effects on PD and PD. The stilbene disulfonate derivate SITS (≤10 mol·l, both sides) led to a 36±9% inhibition of PD. The present data, apart from supporting the cell model proposed in a preceding report, allow the following conclusions: The transient analysis of the furosemide effects is suggestive for a 2 Cl∶1 Na stoichiometry of the carrier. The furosemide induced reduction in FR suggests that the fall in aleads to a marked reduction in the apical Cl-conductance. Furosemide apparently drives a Cl/cell to passive distribution and PD to the K equilibrium potential. a then approaches a minimal value which is close to that present in nonstimulated RGT segments. Ba leads to an increase in a because it blocks the conductive recycling pathway for this ion. Ouabain does not only inhibit the (Na+K)-ATPase, it also reduces the K-conductance of the basolateral membrane. This explains why a stays high. The cell PD then is dominated by a. The Na 2ClK-carrier increases a further and the cell continues to depolarize. Thus, the depolarization of the cell is not a sign of K loss but indicative of Cl gain. In the presence of furosemide ouabain is devoid of any effect on PD, suggesting that the Na2 ClK-carrier is the only quantitatively important source of Na entry into the RGT cell. [ABSTRACT FROM AUTHOR]

Rectal gland tubules (RGT) of spiny dogfish were dissected and perfused in vitro. Transepithelial PD (PD), resistance (R), the PD across the basolateral membrane (PD) and intracellular chloride and potassium activities ( a, a) were measured. In a first series, 67 RGT segments were perfused with symmetric shark 'Ringers' solution. The bath perfusate contained in addition db-cAMP 10, forskolin 10, and adenosine 10 mol · l. PD was −11±1 ( n=67) mV lumen negative, R 27±2 ( n=47) Ω cm. PD −75±0.4 ( n=260) mV. a and a were 109±22 ( n=4) and 38±4 ( n=36) mmol · l respectively. These data indicate that Cl secretion across the RGT must be an uphill transport process, whereas secretion of Na could be driven by the lumen negative PD. Intracellular K is 14 mV above equilibrium with respect to the basolateral membrane PD and Cl is 23 mV above equilibrium across the apical membrane. In series 2, the conductivity properties of the apical and basolateral membrane as well as that of the paracellular pathway were examined in concentration step experiments. Decrease of the basolateral K concentration led to a rapid hyperpolarization of PD with a mean slope of 19 mV per decade of K concentration change. Addition of 0.5 mmol · l Ba to the bath solution lead to a marked depolarization and abolished the response to K concentration steps. In the lumen a Cl concentration downward step led to a depolarization of the lumen membrane; resulting in a mean slope of 18 mV per decade of Cl concentration change. When dilution potentials were generated across the epithelium, the polarity indicated that the paracellular pathway is cation selective. In series 3 the equivalent short circuit current (I=PD/R) was determined as a function of symmetrical changes in Na concentration, with Cl held at 276 mmol · l, and as a function of symmetrical changes in Cl concentration, with Na held at 278 mmol · l I was a saturable function of Na concentration (Hill coefficient 0.9±0.1, K 4.4 mmol · l, n=7) and also a saturable function of Cl concentration (Hill coefficient 2.0±0.1, K 75 mmol · l, n=11). These data are compatible with the assumption that the carrier responsible for NaCl uptake has a 1 Na per 2 Cl stoichiometry. In series 4, the effect of a K concentration downward step on PD and a transients was followed with high time resolution in the presence and absence of basolateral furosemide (5 · 10 to 10 mol · l) in an attempt to examine whether K reduction on the bath side inhibits NaCl uptake by the carrier system as does e.g. furosemide. The data indicate that removal of K from the bath side exerts an effect comparable to that of furosemide, i.e. it inhibits the carrier. We conclude that NaCl secretion in the RGT cell comprises at the least the following components: In the basolateral membrane, the (Na+K)-ATPase, probably the Na 2 ClK carrier, and a K conductance. In the apical membrane a Cl conductance; and a Na conductive paracellular pathway. [ABSTRACT FROM AUTHOR]

In order to investigate whether the loop diuretic sensitive, sodium-chloride cotransport system described previously in shark rectal gland is in fact a sodium-potassium chloride cotransport system, plasma membrane vesicles were isolated from rectal glands of Squalus acanthias and sodium and rubidium uptake were measured by a rapid filtration technique. In addition, the binding of N-methylfurosemide to the membranes was investigated. Sodium uptake into the vesicles in the presence of a 170 mM KCl gradient was initially about five-fold higher than in the presence of a 170 mM KNO3 gradient. In the presence of chloride, sodium uptake was inhibited 56% by 0.4 mM bumetanide and 40% by 0.8 mM N-methylfurosemide. When potassium chloride was replaced by choline chloride or lithium chloride, sodium uptake decreased to the values observed in the presence of potassium nitrate. Replacement of potassium chloride by rubidium chloride, however, did not change sodium uptake. Initial rubidium uptake into the membrane vesicles was about 2.5-fold higher in the presence of a 170 mM NaCl gradient than in the presence of a 170 mM NaNO3 gradient. The effect of chloride was completely abolished by 0.4 mM bumetanide. Replacement of the sodium chloride gradient by a lithium chloride gradient decreased rubidium uptake by about 40%; replacement by a choline chloride gradient reduced the uptake even further. Rubidium uptake was also strongly inhibited by potassium. Sodium chloride dependence and bumetanide inhibition of rubidium flux were also found in tracer exchange experiments in the absence of salt gradients. The isolated plasma membranes bound 3[H]-N-methylfurosemide in a dose-dependent manner. In Scatchard plots, one saturable component could be detected with an apparent KD of 3.5 x 10(-6) M and a number of sites n of 104 pmol/mg protein. At 0.8 microM, N-methylfurosemide binding decreased 51% when sodium-free or low-potassium media were used. The same decrease was observed when the chloride concentration was increased from 200 to 600 mM or when 600 1 mM bumetanide or furosemide was added to the incubation medium. These studies indicate that the sodium-chloride cotransport system described previously in the rectal gland is in fact a sodium-potassium chloride cotransport system. It is postulated that this transport system plays an essential role in the secondary active chloride secretion of the rectal gland. [ABSTRACT FROM AUTHOR]

The occurrence and distribution of endocrine cells and nerves were immunohistochemically demonstrated in the gut and rectal gland of the ratfish Chimaera monstrosa (Holocephala). The epithelium of the gut mucosa revealed open-type endocrine cells exhibiting immunoreactivity for serotonin (5HT), gastrin/cholecystokinin (CCK), pancreatic polypeptide (PP)/FMRFamide, somatostatin, glucagon, substance P or gastrin-releasing peptide (GRP). The rectum contained a large number of closed-type endocrine cells in the basal layer of its stratified epithelium; the majority contained 5HT- and GRP-like immunoreactivity in the same cytoplasm, whereas others were immunoreactive for substance P. The rectal gland revealed closed-type endocrine cells located in the collecting duct epithelium. Most of these contained substance P-like immunoreactivity, although some reacted either to antibody against somatostatin or against 5HT. Four types of nerves were identified in the gut and the rectal gland. The nerve cells and fibers that were immunoreactive for vasoactive intestinal peptide (VIP) and GRP formed dense plexuses in the lamina propria, submucosa and muscular layer of the gut and rectal gland. A sparse network of gastrin- and 5HT-immunoreactive nerve fibers was found in the mucosa and the muscular layer of the gut. The present study demonstrated for the first time the occurrence of the closed-type endocrine cells in the mucosa of the rectum and rectal gland of the ratfish. These abundant cells presumably secrete 5HT and/or peptides in response to mechanical stimuli in the gut and the rectal gland. The peptide-containing nerves may be involved in the regulation of secretion by the rectal gland. [ABSTRACT FROM AUTHOR]

The anatomy, histology, ultrastructure and ATPase activity of the intramural rectal gland of the chondrichthyean Hydrolagus colliei, are described. The cells of the rectal gland of Hydrolagus demonstrate the same well developed lateral and basal cisternae, elongate mitochondria and luminal border as those of their elasmobranch counterparts. ATPase activity within the rectal gland of Hydrolagus is as intense as that in a number of elasmobranchs examined in the course of the study. Despite its primitive intramural location the rectal gland of Hydrolagus respresents a homolog of the more specialized and better known elasmobranch gland and appears as well suited for cation excretion. [ABSTRACT FROM AUTHOR]

Tissue from the digitiform rectal gland of the spiny dogfish, Squalus acanthias, was fixed briefly by formaldehyde perfusion and studied for the specificity and localization of p-nitrophenyl phosphatase (NPP'ase) activity. The enzymatic activity was K-dependent (56%) and ouabain-sensitive (67% inhibition). The electron-dense reaction product (SrPO) of the cytochemical reaction (Ernst, 1972b) was localized along the inner surfaces of the basolateral membranes of the secretory cells. It was absent from mitochondria, nuclei, vesicles, and other organelles. The luminal surface of the secretory cells was slightly reactive. On the basis of (1) this pattern of localization for the sodium transport system, (2) the presence of extensive intercellular labyrinthine channels (Bulger, 1963) that would facilitate 'standing gradients' (Diamond and Bossert, 1968), and (3) the specific distribution of the energy-providing mitochondria, we conclude that the concentration and electrochemical gradients recorded from the secreting gland (Hayslett et al., 1974) are maintained across the domains of the basolateral surfaces of the secretory cells. [ABSTRACT FROM AUTHOR]