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The activation of metal-oxo species with Lewis acids is of current interest. In this work, the effects of a weak Brønsted acid such as CH 3 CO 2 H and a weak Lewis acid such as Ca 2+ on C-H bond activation by KMnO 4 have been investigated. Although MnO 4 - is rather non-basic (p K a of MnO 3 (OH) = -2.25), it can be activated by AcOH or Ca 2+ to oxidize cyclohexane at room temperature to give cyclohexanone as the major product. A synergistic effect occurs when both AcOH and Ca 2+ are present; the relative rates for the oxidation of cyclohexane by MnO 4 - /AcOH, MnO 4 - /Ca 2+ and MnO 4 - /AcOH/Ca 2+ are 1 : 73 : 198. DFT calculations show that in the active intermediate of MnO 4 - /AcOH/Ca 2+ , MnO 4 - is H-bonded to 3 AcOH molecules, while Ca 2+ is bonded to 3 AcOH molecules as well as to an oxo ligand of MnO 4 - . Our results also suggest that these synergistic activating effects of a weak Brønsted acid and a weak Lewis acid should be applicable to a variety of metal-oxo species., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Objective: The use of virtual learning in psychiatric education has been required to address COVID-19-related challenges. Research regarding the implementation of virtual teaching environments and standardized patients for simulation remains limited. Here, educators' outcomes were evaluated following a transition from in-person teaching with "real" patients, to a standardized patient-based simulation in pre-clerkship psychiatric clinical skills teaching for medical students., Methods: The Integrated Clinical Experiences course at the University of Toronto is a pre-clerkship clinical skills curriculum for second-year medical students. Four psychiatric clinical skills sessions were transitioned from in-person teaching to virtual teaching environments with standardized patient-based simulation. Educators (tutors) were assigned to teach groups of four to seven medical students, with a total of 45 groups. Tutors were then asked to complete an online questionnaire, and data was analyzed by quantitative and qualitative means., Results: Of 30 tutors, 21 (75.0%) had previously taught the course for an average of 6.52 ± 6.85 years. Twenty-four of 30 (80%) tutors described their ease of virtual teaching as "extremely easy" or "moderately easy". Twenty-three of 30 (76.6%) were "extremely satisfied" or "moderately satisfied" with standardized patient-based simulation. Various advantages and disadvantages of the virtual teaching environment with standardized patient-based simulation were identified., Conclusions: The transition to a virtual teaching environment utilizing standardized patients in a pre-clerkship simulation-based curriculum did not result in significant challenges that would limit educators' use of these teaching tools. Implementation of virtual teaching environments with standardized patients may thus serve to address challenges related to COVID-19 and resource limitations., (© 2021. Academic Psychiatry.)

Embryo vitrification involves exposure to high concentrations of cryoprotectants and osmotic stress during cooling and warming in the cryopreservation process. Many of these factors can potentially affect gene expression. In this study, invitro-produced bovine embryos at the blastocyst stage were subjected to vitrification. Four recipients each were used for transferring non-vitrified (n=80) and vitrified (n=80) embryos. A total of 12 non-vitrified and 9 vitrified viable day-14 (D14) embryos were recovered by uterine flushing. RNA-seq analysis of the whole embryo or isolated trophectoderm (TE) from vitrified and fresh recovered D14 embryos revealed a total of 927 and 4376 genes with changed expression in embryos and TE isolates, respectively, as a result of vitrification. In addition, we found 671 and 61 genes commonly up- or downregulated in both vitrified whole embryos and TE. Commonly upregulated pathways by vitrification included epithelial adherens junctions, sirtuin signalling, germ cell-sertoli cell junction, ATM signalling, NER and protein ubiquitination pathways. The commonly downregulated pathways included EIF2 signalling, oxidative phosphorylation, mitochondrial dysfunction, regulation of eIF4 and p70S6K signalling and mTOR signalling pathways. Our analysis identified specific pathways and implicated specific gene expression patterns affecting embryo developmental competence that are important to cryopreservation.

Metal oxo (M[double bond, length as m-dash]O) complexes are common oxidants in chemical and biological systems. The use of Lewis acids to activate metal oxo species has attracted great interest in recent years, especially after the discovery of the CaMn 4 O 5 cluster in the oxygen-evolving centre of photosystem II. Strong Lewis acids such as Sc 3+ and BF 3 , as well as strong Brønsted acids such as H 2 SO 4 and CF 3 SO 3 H, are commonly used to activate metal oxo species. In this work, we demonstrate that relatively weak Lewis acids such as Ca 2+ and other group 2 metal ions, as well as weak Brønsted acids such as CH 3 CO 2 H, can readily activate the stable RuO 4 - complex towards the oxidation of alkanes. Notably, the use of Ca 2+ and CH 3 CO 2 H together produces a remarkable cooperative effect on RuO 4 - , resulting in a much more efficient oxidant. DFT calculations show that Ca 2+ and CH 3 CO 2 H can bind to two oxo ligands to form a chelate ring. This results in substantial lowering of the barrier for hydrogen atom abstraction from cyclohexane., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The synthesis and X-ray structure of a new manganese(V) mesitylimido complex with a tetraamido macrocyclic ligand (TAML), [Mn V (TAML)(N-Mes)] - (1), are reported. Compound 1 is oxidized by [(p-BrC 6 H 4 ) 3 N] +. [SbCl 6 ] - and the resulting Mn VI species readily undergoes H-atom transfer and nitrene transfer reactions., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Background and Purpose: A mindfulness yoga program (MiYoga) was developed and trialled with children with cerebral palsy and their parents. This mixed-method study explores the experiences of children and parents who participated in MiYoga, to assess its acceptability, feasibility and implementation., Materials and Methods: Of the forty-two child-parent dyads who participated in the MiYoga randomised control trial, 19 children and 22 parents were interviewed individually in a semi-structured way about their experiences of MiYoga. Participants rated their mood on a 5-point scale before and after each session and completed short questionnaires at the end of each session., Results: Children and parents reported improved mood after each MiYoga session. Parents reported being more aware of their thoughts and feelings and possibly became more aware of their day-to-day mindlessness., Conclusion: MiYoga significantly improved children and parents' mood. Parents reported gains in awareness as well as challenges of adhering to the home practice., (Copyright © 2018. Published by Elsevier Ltd.)

Milk fever is an important metabolic disorder that affects dairy cows around parturition. It is associated with a breakdown in the mechanisms of calcium homeostasis, resulting in very low blood calcium levels (hypocalcemia). The main objective of this study was to dissect the genetic basis underlying milk fever incidence in Holstein cattle. Data consisted of 31.6 k producer-recorded lactation incidence records from 15.3 k cows. The analysis included a whole-genome scan and a subsequent gene-set analysis in order to reveal individual genes, genetic mechanisms and biological pathways implicated in the incidence of periparturient hypocalcemia. The association analysis identified at least eight different genomic regions that explain considerable amounts of additive genetic variance for milk fever incidence. Notably, some of these regions harbor genes, such as CYP27A1, CYP2J2, GC, SNAI2 , and PIM1 , that are directly involved in vitamin D metabolic pathway. Moreover, the gene-set analysis revealed several functional terms, such as calcium ion binding, calcium ion transportation, T cell differentiation, B cell activation, protein phosphorylation, apoptosis, and protein kinase activity, among others, that could be implicated in the development of periparturient hypocalcemia. Overall, this comprehensive study contributes to a better understanding of the genetic control of this complex disease. In addition, these findings may contribute to the development of novel breeding strategies for reducing the incidence of milk fever in dairy cattle.

An outbreak of reproductive failure in a pig farm in Taiwan was investigated. Coinfection with porcine circovirus type 2 (PCV2) and porcine reproductive and respiratory syndrome virus (PRRSV) was diagnosed in a stillborn pig by histopathology, polymerase chain reaction, and immunohistochemistry, and should be considered as a cause of reproductive failure.

We conducted a retrospective study to assess the accuracy of fine-needle aspiration cytology (FNAC) in the diagnosis of Warthin tumor and to evaluate the subsequent risk of conservative nonsurgical management. We reviewed the records of 75 patients (76 tumors) with a parotid mass that had been diagnosed as a Warthin tumor by FNAC. This patient population was made up of 64 men and 11 women, aged 46 to 93 years (mean: 67). Of the 76 tumors, 40 were treated with surgical excision and 36 with conservative measures. Histology of the 40 excised parotid masses revealed that 38 (95%) were indeed Warthin tumors, 1 (2.5%) was a low-grade adenocarcinoma, and 1 was benign-not otherwise specified. None of the 36 tumors underwent malignant transformation either clinically or on repeat FNAC (if performed) during a follow-up of 4 to 120 months (mean: 55.5 ± 32.2). We conclude that conservative management of Warthin tumors confidently diagnosed on FNAC may be an option for patients who are unwilling or unable to undergo surgical excision.

Thyroxine (T4) is one of the major thyroid hormones, which regulates cellular metabolism, central nervous system development, body temperature, reproduction and growth. The simulation of oxidation reactions of T4 may provide further information about the fate of T4 in cells without using laborious in vitro and susceptible in vivo tests. In this study, oxidation products of T4, generated inside an electrochemical (EC) cell, were separated and identified by on-line EC/liquid chromatography/electrospray ionization-mass spectrometry (EC/LC/ESI-MS). In another experimental setup, the electrogenerated metabolites were separated by LC, subsequently mixed with a compensating countergradient (cg), and finally introduced into an inductively coupled plasma-mass spectrometer (ICP-MS). The gradient compensation was achieved by an additional pump module which generated a reversed gradient to the analytical gradient used for the separation. This setup enabled a constant composition of the LC eluent flowing into the plasma so that stable plasma conditions and a uniform response over the complete elution time could be achieved. Combined with identification information from online-coupled EC/LC/ESI-MS, robust and reliable quantification of T4 and its oxidation products was accomplished by on-line coupled EC/cgLC/ICP-MS, with LOD of 33nM of iodine., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Background: Nasopharyngeal carcinoma is a distinct type of head and neck cancer which is consistently associated with Epstein-Barr virus (EBV). The C666-1 cell line is the only in vitro native EBV-infected NPC cell model commonly used for study of the viral-host interaction. Nevertheless, the complete EBV genome sequence in this in vitro EBV-infected NPC model has not been characterized., Objective: To determine the complete EBV genome sequence in C666-1 cells., Methods: The C666-1 genome was sequenced by 100-bases pair-end massive parallel sequencing. Bioinformatics analysis was performed to extract the EBV sequences and construct an EBV consensus sequence map. PCR amplification and Sanger DNA sequencing were used for sequence validation and gap filling. A phylogenetic analysis of EBV strain in C666-1 cells and other reported EBV strains was performed., Results: A 171,317 bp complete EBV genome of C666-1 was successfully constructed (GenBank accession number: KC617875). Phylogenetic analysis of EBV genome in C666-1 revealed that the C666-1 EBV strain is closely related to the reported strains in NPC primary tumors., Conclusion: C666-1 contains a representative NPC-associated EBV genome and might serve as an important model for studying the roles or function of viral proteins in NPC tumorigenesis.

Recent reports have highlighted several parameters of the neurosphere culture or assay system which render it unreliable as a quantitative in vitro assay for measuring neural stem cell (NSC) frequency. The single-step semi-solid based assay, the Neural Colony Forming Cell (NCFC) assay is an assay which was developed to overcome some of the limitations of the neurospheres assay in terms of accurately measuring NSC numbers. The NCFC assay allows the discrimination between NSCs and progenitors by the size of colonies they produce (i.e. their proliferative potential). The NCFC assay and other improved tissue culture tools offer further advances in the promising application of NSCs for therapeutic use.

Since the discovery of neural stem cells (NSC) in the embryonic and adult mammalian central nervous system (CNS), there have been a growing numbers of tissue culture media and protocols to study and functionally characterize NSCs and its progeny in vitro. One of these culture systems introduced in 1992 is referred to as the Neurosphere Assay, and it has been widely used to isolate, expand, differentiate and even quantify NSC populations. Several years later because its application as a quantitative in vitro assay for measuring NSC frequency was limited, a new single-step semisolid based assay, the Neural Colony Forming Cell (NCFC) assay was developed to accurately measure NSC numbers. The NCFC assay allows the discrimination between NSCs and progenitors by the size of colonies they produce (i.e., their proliferative potential). The evolution and continued improvements made to these tissue culture tools will facilitate further advances in the promising application of NSCs for therapeutic use.

Background: Although Dickkopf-1 (DKK1) is known to be a negative regulator of the Wnt/β-catenin pathway, it has been recently found to be upregulated in cancers., Aims: We investigated the clinical and prognostic significance of both serum and transcript DKK1 and its functional roles in human hepatocellular carcinoma (HCC)., Methods: We evaluated the expression level of DKK1 in both tissue and serum samples from patients with HCC using GeneChip microarray and real-time-quantitative PCR and sandwich ELISA system respectively. The clinicopathological and prognostic significance of serum and tissue DKK1 levels was examined. Functional characterization of DKK1 with regard to cell migration, invasion and tumour growth was performed., Results: Both DKK1 transcript and serum protein were upregulated in a stepwise manner in human HCCs. Its transcript levels were associated with more aggressive tumour behaviour, in terms of venous invasion (P = 0.003), advanced tumour stage (P = 0.003). DKK1 transcript correlated with shorter overall (P = 0.006) and disease-free survival (P = 0.012), and higher serum DKK1 levels correlated with shorter disease-free survival (P = 0.046). Knockdown of DKK1 significantly reduced both migratory and invasive abilities of HCC cells, whereas overexpression of DKK1 enhanced the tumour formation efficiency and tumour growth in vivo., Conclusions: Serum and tissue DKK1 levels increased in a stepwise manner in multistep hepatocarcinogenesis and had prognostic significance. DKK1 plays a functional role in cell migration, invasion and tumour growth., (© 2011 John Wiley & Sons A/S.)

Objective: RSD1235 is a novel antiarrhythmic drug with atria-selective electrophysiological actions on Na(+) and K(+) currents. The mechanism for its protection of ventricular repolarization was assessed by its action on Purkinje fibers, and by block of late sodium current active during repolarization. Further, RSD1235's ability to reverse the pro-arrhythmic actions of the class III agents dofetilide and clofilium was assessed in isolated Purkinje fibers and an in vivo model of torsades de pointes (TdP)., Methods: Action potential and early after-depolarization (EAD) recordings were made from in situ and isolated rabbit Purkinje fibers at 37 degrees C using floating sharp microelectrodes; late I(Na) was recorded using a whole-cell patch clamp technique of Nav1.5 expressed in HEK cells at 22 degrees C; In vivo, anesthetized methoxamine-sensitized rabbits were used to test the ability of RSD1235 to suppress clofilium-induced TdP., Results: RSD1235 (0.5-30 microM) had minor dose-dependent effects on action potential duration (APD) at 50% and 90% repolarization in Purkinje fibers, but pre-treatment significantly attenuated the APD-prolonging effects of dofetilide (300 nM). EADs induced by 300 nM dofetilide were terminated by 30 microM RSD1235 in all experiments (n=7). RSD1235 blocked a late component of Na current (I(Na)), which can produce inward currents contributing to EAD formation. RSD1235 pre-treatment (1 micromol/kg/min) or acute infusions prevented/terminated TdP induced by clofilium in 8 of 9 rabbits, and reduced the duration of TdP episodes from 71 +/- 23 s in control to 17 +/- 7 and 14 +/- 14 s at infusion rates of 0.3 and 1.0 micromol/kg/min, respectively (n = 9, p < 0.001)., Conclusion: RSD1235 itself has minor actions on repolarization in Purkinje fibers, but can reverse the AP-prolonging actions of class III agents and terminate arrhythmias in a model of TdP. We suggest that these protective actions of RSD1235 may result, at least in part, from its ability to inhibit late I(Na) during action potential repolarization.

Dinoflagellate genomes are large (up to 200 pg) and are encoded in histoneless chromosomes that are quasi-permanently condensed. This unique combination of chromosomal characteristics presents additional topological and cell cycle control problems for a eukaryotic cell, potentially exhibiting novel regulatory requirements of topoisomerase II. The heterotrophic dinoflagellate Crypthecodinium cohnii was used in this study. The topoisomerase II activities throughout its cell cycle were investigated by DNA flow cytometry following enzyme deactivation. Fluorescence microscopy was also used for studying the chromosome morphology of the treated cells. Two classes of topoisomerase II inhibitors were applied in our study, both of which caused G1 delay as well as G2/M arrest in the C. cohnii cell cycle. At high doses, the topoisomerase poisons amsacrine and ellipticine induced DNA fragmentation in C. cohnii cells. Topoisomerase II activities, as measured by the ability to decatenate kinetoplastid DNA (kDNA), are normally detected throughout the cell cycle in C. cohnii. Our results suggest that the requirement of type II topoisomerase activities during the G1 phase of the cell cycle may relate to the unwinding of quasi-permanently condensed chromosomes for the purpose of transcription. This was also the first time that topoisomerase II activity in dinoflagellate cells was detected.

Severe acute respiratory syndrome (SARS) is a recently emerged infectious disease caused by a novel strain of coronavirus. Examination of the immune responses of patients who have recovered from SARS should provide important information for design of a safe and effective vaccine. We determined the continuous viral epitopes targeted by antibodies in plasma samples from convalescent SARS patients through biopanning with a vast M13 phage display dodecapeptide library. These epitopes converged to very short peptide fragments, one on each of the structural proteins spike and nucleocapsid and the nonstructural proteins 3a, 9b, and nsp 3. Immunoassays found that most of the patients who had recovered from SARS developed complementary antibodies to the epitope-rich region on the spike S2 protein, indicating that this is an immunodominant site on the viral envelope comprising the spike, matrix, and small envelope glycoproteins. These S2-targeting antibodies were shown to effectively neutralize the coronavirus, indicating that they provided protective immunity to help the patients recover from the viral infection. These results suggest that the SARS coronavirus might have an antigenic profile distinct from those of other human or animal coronaviruses. Due to the tested safety and protective effects of the convalescent-phase serological antibodies, identification of their complementary antigens may enable the design of an epitope-based vaccine to prevent potential antibody-mediated immunopathology.

Although the ion [Os(VIII)(N)(O)(3)](-) is a stable species and is not known to act as an oxidant for organic substrates, it is readily activated by FeCl(3) in CH(2)Cl(2)/CH(3)CO(2)H to oxidize alkanes efficiently at room temperature. The oxidation can be made catalytic by using 2,6-dichloropyridine N-oxide as the terminal oxidant. The active intermediates in stoichiometric and catalytic oxidation are proposed to be [(O)(3)Os(VIII)N-Fe(III)] and [Cl(4)(O)Os(VIII)N-Fe(III)], respectively.

A simple and efficient preparation of gramicidin S and its analogues is described. It involves solid-phase peptide synthesis and on-resin macrolactamization without side chain protection, affording cyclic products in high yield and high purity. The high specificity of the cyclization reaction was shown to originate in the formation of a pre-organized conformation of the linear biosynthetic precursor of gramicidin S. This facile method will provide convenient access to the analogues of the natural product for functional optimization to counter microbial resistance.

Background: There is concern about the oncological safety of preserving most of the breast skin in skin-sparing mastectomy (SSM). Most supportive evidence for SSM evaluates the local recurrence rate on clinical follow-up., Methods: The skin and 10 mm of the subcutaneous tissue of 30 total mastectomy specimens were studied with a step-serial sectioning technique. The incidence and mode of involvement of the skin and subcutaneous tissue were recorded in detail. This was correlated with other clinical and pathologic parameters., Results: The incidence of skin involvement outside the nipple-areola complex was 20% (6 of 30). This was significantly related to the clinical T stage, site of the tumor, skin tethering, pathologic tumor size, and perineural infiltration. When the effects of both skin and subcutaneous tissue involvement were considered, the incidence of skin-flap involvement outside the nipple-areola complex was 23% (7 of 30). The significant parameters related to skin-flap involvement were skin tethering (75% vs. 15%; P <.05), pathologic tumor size (P <.03), and perineural infiltration (63% vs. 9%; P <.01)., Conclusions: It would be oncologically safe to perform SSM in T1 and T2 tumors, because the chance of skin involvement is small. It is safe to preserve the skin overlying the tumor if there is no skin tethering.

The ruthenium(II) complex cis-[Ru(6, 6'-Cl(2)bpy)(2)(OH(2))(2)](CF(3)SO(3))(2) (1) is a robust catalyst for C-H bond oxidations of hydrocarbons, including linear alkanes, using tert-butyl hydroperoxide (TBHP) as terminal oxidant. Alcohols can be oxidized by the "1 + TBHP" protocol to the corresponding aldehydes/ketones with high product yields at ambient temperature. Oxidation of 1 with Ce(IV) in aqueous solution affords cis-[Ru(VI)(6, 6'-Cl(2)bpy)(2)O(2)](2+), which is isolated as a green/yellow perchlorate salt (2). Complex 2 is a powerful stoichiometric oxidant for cycloalkane oxidations under mild conditions. Oxidation of cis-decalin is highly stereoretentive; cis-decalinol is obtained in high yield, and formation of trans-decalinol is not observed. Mechanistic studies showing a large primary kinetic isotope effect suggest a hydrogen-atom abstraction pathway. The relative reactivities of cycloalkanes toward oxidation by 2 have been examined through competitive experiments, and comparisons with Gif-type processes are presented.

Biliary papillomatosis is a rare tumor of the intrahepatic and extrahepatic biliary tree, and its FNA findings have not been reported. The cytologic features of 3 cases of intrahepatic biliary papillomatosis were studied and compared with 5 cases of cholangiocarcinoma. The distinctive features include: 1) hypercellular smear, 2) very broad and often double-cell layered sheets of ductal columnar epithelium, 3) papillary configuration, 4) preserved honeycomb pattern with even nuclear spacing, and 5) dysplastic but not frankly malignant nuclear features. The constellation of these features is highly characteristic of biliary papillomatosis and helpful in distinguishing it from cholangiocarcinoma and other differential diagnoses. A firm preoperative diagnosis can thus be achieved, allowing better planning in management of this borderline malignant tumor., (Copyright 2000 Wiley-Liss, Inc.)

We report a female patient suffering from cytomegalovirus (CMV)-induced tubulointerstitial nephritis in a renal allograft 70 days after a cadaveric renal transplantation. CMV-induced renal allograft injury reported in the literature mainly related to immune-mediated mechanisms. In our patient, acute tubulointerstitial nephritis, associated with histological evidence of CMV infection, was demonstrated in the renal allograft biopsy. There were no histological features of allograft rejection, cyclosporin nephrotoxicity nor 'CMV glomerulopathy'. She was successfully treated by foscarnet therapy and a reduction in immunosuppression. Her renal function returned to baseline afterwards., (Copyright 2000 S. Karger AG, Basel)

Strongyloides stercoralis infection is known to be important because of its potential for life-threatening disseminated infection in immunosuppressed hosts. Apart from direct invasion into nearly every organ in systemic infection, evidence suggests that immunological reaction also plays a role in the pathogenesis of the disease, including both uncomplicated and disseminated infections. However, Strongyloides-related glomerulonephritis has not been well documented. We present a case of steroid- and cyclophosphamide-resistant nephrotic syndrome complicated by disseminated strongyloidiasis which responded to anthelmintic agents. The remission of nephrotic syndrome after treatment of Strongyloides infection strongly suggests the possibility of Strongyloides-associated glomerulonephritis. Nephrotic patients in endemic areas of Strongyloides infection should have the differential white cell count checked. Strongyloides infection should be ruled out in patients with eosinophilia before immunosuppressants are initiated to prevent the complication of disseminated strongyloidiasis.

An unusual example of mammary myofibroblastoma in a 36-year-old woman was reported. The central portion resembled mammary myofibroblastoma or solitary fibrous tumor of other sites and showed reactivity for CD34 and muscle-specific actin, with few cells staining for desmin. The peripheral portion resembled leiomyoma and showed strong reactivity for actin and desmin but only focal staining for CD34. We interpret this tumor as mammary myofibroblastoma showing frank peripheral leiomyomatous differentiation. Although closely related to solitary fibrous tumor, mammary myofibroblastoma appears slightly different because of its consistent slant toward myoid differentiation in the form of actin and variable desmin reactivity as opposed to the rare and sparse immunohistochemical expression of myoid features by solitary fibrous tumors of other sites. This case demonstrates this phenomenon carried to an extreme, a feature not previously documented in mammary myofibroblastoma. It is of interest to note the modulation of the antigenic profile with the differentiation process, that is, loss of CD34 and gain of desmin accompanying the myoid differentiation.

Modern drug discovery demands accurate knowledge of the drug properties of affinity and efficacy at specific receptor proteins. Furthermore, drugs with well defined properties make better tools with which to explore and understand receptor regulation. The use of clonal cell lines stably expressing a given recombinant receptor may provide a highly useful model in which drug effects may be studied on one receptor subtype at a time. The present report was designed to evaluate the utility of a general method in which a clonal cell line stably expressing a recombinant D1A dopamine receptor was used as a model system for studying drug actions by null models. The null model for receptor occlusion (to calculate agonist Ka) and the null model for relative efficacy (to calculate test agonist affinity and epsilon r) were evaluated in these studies. To initiate these studies, rat C6 glioma cells that do not normally express DA receptors have been modified by stable transfection with the primate D1A DA receptor [Machida et al., 1992 (Molec. Pharmacol. 41: 652-659)] to a density of approximately equal to fmol/mg protein. The recombinant receptors show robust stimulation of cAMP in the stably transfected C6 cells. Calculation of agonist Ka from dose-response data requires that a portion of the cell's receptors be occluded in the absence of changes in post-receptor events leading to the response. Receptor reserve is typically reduced by alkylation, thereby lowering maximal response. Unfortunately, most of the currently available alkylating agents are not selective either for a particular receptor or for receptors vs other proteins within a signaling pathway. Short-term agonist treatment offers a possible complement to the use of non-selective or poorly characterized alkylating drugs for reducing maximum response in appropriate cell systems. The null method of receptor occlusion was used to determine the Ka for dopamine when maximum response was decreased by alkylation vs short-term agonist treatment. Direct non-linear curve fitting was used to analyze the data. In addition to DA, two other compounds were used to reduce receptor reserve to validate the method: fenoldopam (relatively high efficacy) and SKF38393 (low efficacy). Analyses indicated that the affinity of DA was similar whether calculated by alkylation (1.1 +/- 0.58 microM), 75 min DA treatment (0.57 +/- 0.16 microM) or 45 min treatment with DA (0.86 +/- 0.11 microM). Short-term agonist treatment experiments using multiple concentrations of DA, fenoldopam, or SKF38393 to decrease receptor reserve provided additional support for the validity of the Ka determinations using this procedure. Other experiments were conducted according to the null model for relative efficacy in which the affinity for DA is calculated by comparing the DA response before and after receptor occlusion, and the affinity and relative intrinsic efficacy of the test agonist are determined as a function of its actions relative to DA. We used the following four test drugs: + Br-APB, a novel agent with potential dopamine agonist properties, and three high-affinity DA agonists, fenoldopam, R-(-)-apomorphine (APO), and SKF38393. Intrinsic efficacy values relative to that of DA (1.0) were as follows: fenoldopam, 0.46 +/- 0.11; APO, 0.19 +/- 0.13; SKF38393, 0.07 +/- 0.01; and +Br-APB, 0.26 +/- 0.40. The agonist affinities (Ka) were: fenoldopam, 0.018 +/- 0.008 microM; APO, 0.80 +/- 0.18 microM; SKF38393, 0.16 +/- 0.04 microM; BR-APB, 0.43 +/- 0.29 microM; and DA, 0.58 +/- 0.17 microM. EC50/Ka ratios were consistent with relative intrinsic efficacies and Ka values were similar to KL values reported for membrane binding studies. Finally, Monte Carlo simulations were conducted to determine the precision of the parameter estimates...

Since the introduction of the peritoneal equilibration test (PET) by Twardowski in 1987, it became a widely accepted test that provided useful prognostic information on continuous ambulatory peritoneal dialysis (CAPD). It had been shown to be a readily reproducible test if the standard procedure was followed. Although there was wide interpersonal difference in the test results, the mean and range (and standard deviation, SD) were remarkably similar as suggested by Davies et al. in 1993 (3). We had performed PET on our CAPD patients for a few years, and all along we used the reference range established by Twardowski to classify our patients into High, High average, Low average, and Low transporters because no reference range had ever been established in Chinese. The aim of this study was to define the normal mean and range of the PET results in Chinese CAPD patients. We analyzed 100 PET results from 100 Chinese CAPD patients. The mean +/- (SD) of the ratio of dialysate/plasma of creatinine and glucose at four-hour dwell times were 0.71 (0.15) and 0.37 (0.12), respectively. There was a significant difference in the dialysate/plasma ratio of creatinine (p < 0.01) while that of glucose was similar when compared with those found by Twardowski. There was no difference in the solute transfer in diabetic and nondiabetic patients. We concluded that the creatinine clearance of the peritoneal membrane in Chinese CAPD patients was higher than the previously reported result in North American patients.

Segmental dilatation of the colon is rare, usually affecting older children, and may mimic Hirschsprung's disease. A neonate with Down's syndrome and malrotation presented with this condition and was cured by segmental resection.

Our objective was to determine the relationship between major histocompatibility complex class I molecule expression and the tumorigenic properties of cutaneous neoplasms induced by ultraviolet radiation or chemical carcinogens. All tumors tested were found to express low constitutive levels of MHC class I molecules in vitro as determined by indirect immunofluorescence and flow cytometry. Those tumors capable of growth in UVR-exposed but not in normal recipients (regressors) were found to express enhanced levels of H-2Kk following incubation in the presence of gamma-IFN. In contrast, only one of the tumors that were capable of growth in normal recipients (progressors) exhibited more than moderate enhancement of H-2Kk expression in response to gamma-IFN. Analysis of tumor variants obtained by conversion of a UVR-induced regressor tumor to the progressor phenotype by passage through sublethally gamma-irradiated hosts, or the generation of regressor tumors by mutagen exposure of a benz [A] pyrene (BAP) induced progressor tumor, further supported the direct relationship between tumor immunogenicity in vivo and the capacity to elevate H-2Kk expression in response to gamma-IFN. No correlation existed between H-2Dk expression by the tumors and their transplantation phenotype. Furthermore, we failed to observe MHC class II expression by any of the tumors tested. Finally, the growth rate of a regressor tumor implanted into UVR-exposed hosts was significantly reduced if the tumor was pretreated with gamma-IFN in vitro prior to inoculation. This result suggests that UVR-exposed animals may be deficient in their ability to enhance the expression of MHC class I molecules on developing tumors. This alteration may, in part, account for the state of tumor susceptibility caused by UVR exposure.