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During transit through the female reproductive tract, sperm encounter metabolites and environmental conditions that modulate various processes leading to fertilization. Intracellular Ca 2+ dynamics regulate the acrosome reaction (AR), which involves exocytosis of the acrosomal granule, a prerequisite for successful fertilization. We explored the ability of progesterone, prostanglandin-E1, and GABA to induce Ca 2+ mobilization and AR in single human spermatozoa capacitated under external pH (pH e ) conditions found in different regions of the female reproductive tract (pH e 6.5, 7.4 and 8.0). The highest percentage of AR induction, regardless of the inducer, occurred when sperm were capacitated at pH e 7.4. Interestingly, at pH e 6.5 a high percentage of cells exhibit Ca 2+ oscillations, which prevent AR. These oscillations involve extracellular and intracellular Ca 2+ channels. Pharmacological inhibition of Ca 2+ oscillations restores the ability of spermatozoa to undergo the AR when exposed to progesterone, even if capacitated at pH e 6.5. [ABSTRACT FROM AUTHOR]

During the growth of Japanese cows, the ruminal pH value is an important physiological parameter, which remarkably affects their nutritional status. To monitor the health condition of the cows and help farmers efficiently manage their livestock, a clear need exists to develop a novel method to efficiently sense the daily range of the rumen pH. Thus, we developed a solid-state pH sensor for real-time monitoring of the rumen pH value of Japanese cows. The indium tin oxide and field-effect transistor-based pH sensor was fabricated and well packaged, and its performance was comprehensively evaluated. The isolation resistance and waterproofing of the packaged sensor were measured, and the functional features fully satisfied the specific requirements. The power consumption of the developed sensor was measured and calculated. The compact pH sensor only incurred a power consumption of 8.2 × 10 mA h, which is a low value for a cell battery-powered system. Stability test of the packaged pH sensor was performed, and the developed sensor could well measure an acid solution with a stable output for a relatively long time. The output characteristic of the pH sensor and its field measurement were also presented in this paper. [ABSTRACT FROM AUTHOR]

Aim To develop and validate pH-cycling model for primary enamel, which was then used to evaluate the anti-caries potential of fluoride toothpastes. Design Human primary enamel slabs were subjected to pH-cycling model for 10 days and maintained for 6 h in demineralizing solution and 18 h in remineralizing solution daily. Twice/day, the slabs were treated. To validate it, the treatments were water or solutions containing 62.5, 125, 250, and 375 μg F/mL. Commercial toothpastes containing no fluoride, 500, 1100, and 1450 μg F/g were evaluated. Demineralization was assessed by percentage of surface hardness loss (% SHL) and cross-sectional hardness (ΔS). Fluoride dose-response effect was analysed by quadratic regression and the effects of toothpastes by Tukey's test. Results Dose-response effect was found between fluoride concentration and % SHL ( R2 = 0.7047; P < 0.01) or ΔS ( R2 = 0.4465; P < 0.01). % SHL and ΔS (mean ± SD) for the group treated with 500 μg F/g toothpaste was 36.6 ± 8.0 and 6298.5 ± 1221.3, respectively, which were significantly higher than those treated with 1100 (25.2 ± 8.7; 4565.7 ± 1122) and 1450 μg F/g (24.2 ± 5.2; 2339.1 ± 879.7) toothpastes. Conclusion The developed pH-cycling model may be used to evaluate and compare the anti-caries potential of toothpaste formulations with low fluoride concentration because it presents dose-response effects on the reduction of primary enamel demineralization. [ABSTRACT FROM AUTHOR]

The highly permeable integument of amphibians renders them vulnerable to chemical characteristics of their environment, especially during the aquatic larval stage. As the cane toad ( Rhinella marina, Bufonidae) invades southwards along the east coast of Australia, it is encountering waterbodies with highly variable conditions of temperature, pH, and salinity. Understanding the tolerance of toads to these conditions can clarify the likely further spread of the invader, as well as the adaptability of the species to novel environmental challenges. We measured salinity in waterbodies in the field and conducted laboratory trials to investigate the impacts of salinity on toad viability. Eggs and tadpoles from the southern invasion front tolerated the most saline conditions we found in potential spawning ponds during surveys [equivalent to 1200 ppm (3.5 % the salinity of seawater)]. Indeed, high-salinity treatments increased tadpole body sizes, accelerated metamorphosis, and improved locomotor ability of metamorphs (but did not affect metamorph morphology). At very low salinity [40 ppm (0.1 % seawater)], eggs hatched but larvae did not develop past Gosner stage 37. Our study shows that the egg and larval life stages of cane toads can tolerate wide variation in the salinity of natal ponds and that this aspect of waterbody chemistry is likely to facilitate rather than constrain continued southward expansion of the toad invasion front in eastern Australia. [ABSTRACT FROM AUTHOR]

Invasive cane toads are colonizing southeastern Australia via a narrow coastal strip sandwiched between unsuitable areas (Pacific Ocean to the east, mountains to the west).Many of the available spawning sites exhibit abiotic conditions (e.g., temperature, salinity, and pH) more extreme than those encountered elsewhere in the toad's native or already invaded range. Will that challenge impede toad expansion? To answer that question, we measured pH in 35 ponds in northeastern New South Wales and 8 ponds in the Sydney region, in both areas where toads occur (and breed) and adjacent areas where toads are likely to invade, and conducted laboratory experiments to quantify effects of pH on the survival and development of toad eggs and larvae. Our field surveys revealed wide variation in pH (3.9-9.8) among natural water bodies. In the laboratory, the hatching success of eggs was increased at low pH (down to pH 4), whereas the survival, growth, and developmental rates of tadpoles were enhanced by higher pH levels.We found that pH influenced metamorph size and shape (relative head width, relative leg length) but not locomotor performance. The broad tolerance range of these early life-history stages suggests that pH conditions in ponds will not significantly slow the toad's expansion southward. Indeed, toads may benefit from transiently low pH conditions, and habitat where pH in wetlands is consistently low (such as coastal heath) may enhance rather than reduce toad reproductive success. A broad physiological tolerance during embryonic and larval life has contributed significantly to the cane toad's success as a widespread colonizer. [ABSTRACT FROM AUTHOR]

Abstract: Background: Umbilical arterial pH (UApH) in severe cerebral palsy (CP) is not fully understood. Aims: This work aims to determine the relationship between fetal acidemia and clinical features of severe CP. Study design: A retrospective study design is used. Subjects: A review was conducted unti1 April 2013 among 218 infants with CP diagnosed to be caused by antenatal and/or intrapartum conditions determined by the Japan Council for Quality Health Care. After excluding patients in whom the causes of CP were thought to be due to events after delivery, 168 infants born at over 34weeks of gestation that both Apgar score and UApH were measured were selected. Outcome measures: Severe fetal acidemia was defined as a pH of less than 7.0. Results: Six major factors were found to be associated with CP: placental abruption (A, n=42), traumatic delivery with an abnormal FHR pattern (B, n=29), an abnormal FHR pattern during labor (C, n=27), chorioamnionitis with an abnormal FHR pattern (D, n=17), an abnormal FHR pattern before labor (E, n=14), and cord prolapse (F, n=10). The UApH was less than 7.0 in 114 cases (67.9%) and more than 7.20 in 20 cases (11.9%). The UApH values were lowest in group A (median 6.7, 6.43–6.99) and highest in group E (7.18, 6.92–7.45). The distribution of the UApH values was significantly different in these groups. Conclusion: Placental abruption was a factor most associated with low pH. Even among the infants with severe CP, over 10% of patients exhibited a non-acidemic status at birth. [Copyright &y& Elsevier]

The intraerythrocytic malaria parasite is susceptible to oxidative stress and this may play a role in the mechanism of action of some antimalarial agents. Here we show that exposure of the intraerythrocytic malaria parasite to the oxidising agent hydrogen peroxide results in a fall in the intracellular ATP level and inhibition of the parasite's V-type H+-ATPase, causing a loss of pH control in both the parasite cytosol and the internal digestive vacuole. In contrast to the V-type H+-ATPase, the parasite's digestive vacuole H+-pyrophosphatase is insensitive to hydrogen peroxide-induced oxidative stress. This work provides insights into the effects of oxidative stress on the intraerythrocytic parasite, as well as providing an alternative possible explanation for a previous report that light-induced oxidative stress causes selective lysis of the parasite's digestive vacuole. [ABSTRACT FROM AUTHOR]

Previous studies suggest that exogenous nitric oxide ( NO) and NO-dependent signalling pathways modulate intracellular pH ( pHi) in different cell types, but the role of NO in pHi regulation in the heart is poorly understood. Therefore, in the present study we investigated the effect of the NO donors S-nitroso- N-acetyl- dl-penicillamine, spermine NONOate and propylamine propylamine NONOate on pHi in rat isolated ventricular myocytes., Cells were isolated from the hearts of adult Wistar rats and pHi was monitored using the pH-sensitive fluorescent indicator 5-(and-6)-carboxy seminaphtharhodafluor ( SNARF)-1 (10 μmol/L) and a confocal microscope. To test the effect of NO donors on the Na+/H+ exchanger ( NHE), basal pHi in Na+-free buffer and pHi recovery from intracellular acidosis after an ammonium chloride (10 mmol/L) prepulse were monitored. The role of carbonic anhydrase was tested using acetazolamide (50 μmol/L). 4,4-Diisothiocyanatostilbene-2,2′-disulphonic acid (0.5 mmol/L; DIDS) was used to inhibit the Cl−/OH− and Cl−/ [ABSTRACT FROM AUTHOR]

This paper reports on the enhanced fermentative production of glutathione by Saccharomyces cerevisiae NCIM 3454 using a statistical approach and its successive purification by alternative technique. In the first step, one factor at-a-time method was used to examine the effect of carbon sources, nitrogen sources and pH on glutathione (GSH) production. Subsequently, statistical mathematical model was used to identify the optimum concentrations of the key nutrients for higher GSH production. Glutathione production increased significantly from 55.28 to 148.45 mg/L when Saccharomyces cerevisiae NCIM 3454 was cultivated using optimized medium, as compared to basal medium. Further, glutathione production was considerably increased to 163.12 mg/L by using cysteine amino acid as one of the metabolic precursor. In this study aqueous two phase system (ATPS) was found to be most useful technique to abolish contaminating proteins in glutathione purification. Further enhanced purification was carried out by adsorption chromatography (ion exchange) using a variety of Amberlite resins. [ABSTRACT FROM AUTHOR]

Alkaline proteases from the viscera of the goby (Zosterisessor ophiocephalus) were extracted and characterized. Proteolytic crude extract from goby viscera was active and stable in alkaline solution. The optimum pH and temperature were 10.0 and 50°C, respectively, using casein as a substrate. The crude alkaline protease was extremely stable in the pH range of 5.0–12.0. Zymography activity staining using casein as a substrate showed the presence of at least four distinct proteases. The alkaline proteases showed extreme stability toward nonionic surfactants (Tween 80 and Triton X-100) and were relatively stable toward oxidizing agents, retaining more than 60% of their initial activity in the presence of 2% sodium perborate. Furthermore, the alkaline crude enzyme extract showed relative stability and compatibility with commercial liquid and solid detergents. Wash performance analysis revealed that goby crude extract could effectively remove a variety of stains, such as blood and chocolate. Further, alkaline proteases from goby viscera were found to be effective in the deproteinization of shrimp wastes. A high level of deproteinization 80.0% ± 1.5 was recorded with an enzyme/substrate ratio (E/S) of 20 U/mg. These results suggest that enzymatic deproteinization of the shrimp shell wastes, using Z. ophiocephalus proteases, could be applicable to the chitin production process. [ABSTRACT FROM AUTHOR]

Abstract: CO2 tolerance in white sturgeon is associated with the ability to tightly regulate intracellular pH (pHi) despite a large reduction in extracellular pH (pHe) termed preferential pHi regulation. How this regulatory response affects whole animal metabolic rate is unknown. Accordingly, we characterized oxygen consumption rate () and metabolically-relevant organismal and cellular responses in white sturgeon during exposure to hypercarbia. White sturgeon were able to protect intracellular pH (pHi) in liver and white muscle as early as 6h (the earliest time period investigated) following exposure to severe (sub-lethal) hypercarbia (45 and 90mmHg PCO2). Sturgeon exposed to 15 and 30mmHg PCO2 exhibited pHe compensation and significant increases in (up to 80% greater than control values). In contrast, severe hypercarbia (≥45mmHg PCO2) elicited an uncompensated reduction in pHe (up to ~1.0 pH units) and red blood cells (as great as ~0.5 pH units), and was accompanied by 30 and 60% reductions in , respectively. While behavioral, respiratory and cellular responses to hypercarbia were observed, none corresponded well with the pattern or magnitude of changes in . The findings of this research provide empirical support for the hypothesis that preferential pHi regulation is not metabolically costly, and thus may have been a strategy strongly selected for in fishes encountering short-term hypercarbia. [Copyright &y& Elsevier]

A novel surface-display system was constructed using the cell-wall anchor protein Flo1p from Saccharomyces cerevisiae, the mannanase (man1) from Bacillus subtilis fused with the C-terminus of Flo1p and the 6×His tag was inserted between Flo1p and man1. The fusion protein was displayed on the cell surface of Yarrowia lipolytica successfully, and it was confirmed by immunofluorescence. In succession, the surface-displayed mannanase was characterized. The optimum catalytic conditions for the recombinant mannanase were 55 °C at pH 6.0, and it exhibited high stability against pH variation. The highest activity of the recombinant mannanase reached 62.3 IU/g (dry cell weight) after the recombinant was cultivated for 96 h in YPD medium [1% (w/v) yeast extract/2% (w/v) peptone/2% (w/v) glucose]. To our knowledge, the present paper is the first to report that high-activity mannanase is displayed on the cell surface of Y. lipolytica with Flo1p. [ABSTRACT FROM AUTHOR]

Abstract: Oxygen equilibrium data were obtained for intact erythrocytes from Pagrus auratus and the pH-dependence of the fixed-acid Bohr and Root effects described. Indicators of aerobic–anaerobic poise were then measured following a period of strenuous exercise induced by angling capture. Haematological indices and plasma metabolites were evaluated with respect to their potential impact on the blood oxygen transport mechanism. An increase in post-capture haemoglobin content, blood lactate, and glucose were observed. The fall in caudal venous pH from 7.53 to 7.41, reflecting the acid–base status of blood draining the working tail musculature, remained within the operational zone of the maximal fixed-acid Bohr effect (Φ 7.4–7.8 =−0.95), but above the critical pH at which the Root effect suppresses oxygen transport capacity. These stress-induced changes reflect a strategy of optimal O2 unloading to tissues with the Root effect unlikely to be expressed in the swimming vasculature. [Copyright &y& Elsevier]

The gastric pH values are controversial in the literature. Some suggest the dog gastric pH is higher than human and dog gastric pH after fed with particular diet is uncertain. Gastric pH in 16 male beagle dogs was measured using Bravo® pH telemetry system. For the fed study, the dogs received 10 or 200 g of dog dry food (5L18) 15 min before dosing the Bravo® pH capsule, followed by a 50 mL of water to aid in swallowing. It was surprising to find a small, but statistically significantly lower pH in the fed compared to the fasted stomach. The average gastric pH in fasted dogs was 2.05 and 1.08 and 1.26 for 10 and 200 g fed dogs. The average gastric emptying time of the capsule was 1.4, 9.4 and 20 h for fasted, 10 g fed and 200 g fed dogs, respectively. The inter-individual variability was higher in fasted dogs than in fed dogs. The results showed the gastric pH in each colony of dogs can be different from reported values in the literature. It emphasizes that the importance of measuring the pH in each colony when dogs are used to evaluate pharmacokinetics of pH sensitive drugs or formulations. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:2494–2500, 2009 [ABSTRACT FROM AUTHOR]

Abstract: The yeast vacuole plays a crucial role in cell homeostasis including pH regulation and degradation of proteins and organelles. Class C VPS genes code for proteins essential for vacuolar and endosomal vesicle fusion, their deletion results in the absence of a detectable vacuole. We found that single gene deletions of class C VPS genes result in a drastically enhanced sensitivity to treatment with acetic acid whereas sensitivity towards H2O2 remains largely unaffected. Interestingly acetic acid treatment known as an established inducer of yeast apoptosis leads to necrosis in class C VPS deletion strains. Their intracellular pH drops from 6.7 to 5.5 after acetic acid treatment, while in wild type the pH drops to just 6.3. When the intracellular pH in wild type is lowered below pH 5.5 using a higher concentration of acetic acid, the survival rate is similarly low as in the class C VPS mutants, however, the death phenotype is predominantly apoptotic. Hence, the vacuole not only prevents acetic acid induced cell death by buffering the cytosolic pH, but it also has a proapoptotic function. [Copyright &y& Elsevier]

The CLC-1 Cl- channel is abundantly expressed on the plasma membrane of muscle cells, and the membrane potential of muscle cells is largely controlled by the activity of this Cl- channel. Previous studies showed that low intracellular pH increases the overall open probability of recombinant CLC-1 channels in various expression systems. Low intracellular pH, however, is known to inhibit the Cl- conductance on the native muscle membrane, contradicting the findings from the recombinant CLC-1 channels in expressed systems. Here we show that in the presence of physiological concentrations of ATP, reduction of the intracellular pH indeed inhibits the expressed CLC-1, mostly by decreasing the open probability of the common gate of the channel. [ABSTRACT FROM AUTHOR]

Data from a previous study about the effects of pH and of linolenic acid (C18:3n-3) and linoleic acid (C18:2n-6) concentrations on C18:2n-6 biohydrogenation in ruminal cultures were used to calculate the rates and efficiencies of the three reactions of C18:2n-6 biohydrogenation (isomerisation of C18:2n-6 to CLA; reduction of CLA to trans-octadecenoic acids; reduction of trans-octadecenoic acids to stearic acid). First, low pH was confirmed to inhibit isomerisation and was shown to inhibit the second reduction, leading to an accumulation of vaccenic acid. This later effect had only been observed in some in vivo studies using high concentrate diets, because in in vitro experiments, the very low pH frequently used depresses isomerisation which consequently generates very low amount of substrates for reductions whose variations become difficult to ascertain. Second, C18:2n-6 at high concentration was confirmed to saturate its own isomerisation and the increase of CLA production due to high initial C18:2n-6 was shown to inhibit the two subsequent reductions. Third, C18:3n-3 at high concentrations was confirmed to inhibit C18:2n-6 isomerisation. Moreover, the second reduction was shown to be saturated, probably by all trans-octadecenoic acids intermediates of C18:2n-6 and C18:3n-3 biohydrogenation, leading to an accumulation of trans-octadecenoic acids, especially vaccenic acid. This fatty acid is partly desaturated into CLA in the mammary gland, which explains the synergy between C18:2n-6 and C18:3n-3 for milk CLA noticed by others in vivo. This approach helped explain the actions of pH and of C18:2n-6 and C18:3n-3 concentrations on C18:2n-6 biohydrogenation and allows some explanations about differences noticed between studies. [ABSTRACT FROM AUTHOR]

The objective of this research was to investigate the effects of alkaline pH conditions of dishwashing liquids on hand skin of Korean panelists after repeated exposure. A group of 30 persons with normal hands immersed their hands, for a total of 15 min a day for 4 days, into household cleansing solutions adjusted to pH 7.4, 10.0 and 10.8, respectively. The effects of alkalinity of household cleansing solutions on hand skin were evaluated by measuring overall and dry hand-skin grades, as well as the degrees of hand-skin hydration estimated before and after the repeated immersion exposures to the 3 test products. No statistically-significant difference (p>0.05) was found among the parameters from the repeated immersion exposures to the test products. These findings indicate that increases of pH up to 10.8 of household cleansing solutions did not worsen either overall, dry hand-skin conditions or the level of hand-skin hydration. [ABSTRACT FROM AUTHOR]

Presents information on a study on the altered intracellular pH regulation in neutrophils from patients with cystic fibrosis (CF). Demonstration on how pH regulation is altered in neutrophils from CF patients; Contribution of pH regulation in CF neutrophils to pulmonary manifestations of the condition; Methodology; Results and discussion; Conclusion.

Investigates the effects of intracellular pH and extracellular pH on the efflux of rubidium and lithium in isolated rat hearts. Effects of monensin; Effects of dimethylpropionate infusion and washout; Effects of global alkalosis and acidosis; Effect of intracellular alkalosis on lithium efflux.

Presents information on a study which investigated the intracellular pH regulation in human umbilical vein endothelial cells. How the study was conducted; Results of the study; Discussion on the results.

We studied 32 patients with insulin-dependent diabetes mellitus to determine how their rate of mucociliary clearance and their levels of nasal and oral pH compared with those of 10 nondiabetic controls and how these rhinologic measurements varied within different subsets of diabetic patients. Although we found very few statistically significant differences in all our comparisons, we did find that nasal mucociliary clearance and oral pH levels in the diabetic patients were significantly different from those of healthy subjects. [ABSTRACT FROM AUTHOR]

Studies the intracellular pH and its basolateral regulation in isolated proximal-proximal and distal-proximal segments of garter snake renal tubules with oil-filled lumens in the presence and absence of bicarbonate. Control measurements of resting pH; Response of pH to exposure to sodium bicarbonate pulse; Effects of various treatments on rate of recovery from minimum pH to control resting pH.

Analyzes the effects of intracellular pH manipulation to preconditioning in isolated buffer-perfused rat hearts. Non-dependence of the mechanism of preconditioning in glucose-perfused hearts on the alleviation of intracellular acidosis; Inability of increasing intracellular pH to improve functional recovery during ischemia in preconditioned hearts.

Examines the effects of altering extracellular pH on intracellular pH and vascular smooth muscle tension. Assessment of the roles of calcium channels, sodium/proton exchanger and chloride/anion exchanger in regulating muscle responses to altering pH; Evidence that the anion exchange process is more important that the sodium/proton exchange in regulating muscle contraction.

Investigates the effect of an acidic pH on apical sodium-dependent phosphate (Na-Pi) cotransport using opposum kidney cell line. Effects of pH on Na-Pi cotransport; Action of parathyroid hormone on Na-Pi cotransport; Influence of the inhibition of the protein synthesis machinery; NaPi-4 protein abundance after acid incubation.

Examines intracellular pH (pHi) regulation in nonactivated and activated rat hepatic stellate cells (HSC). pHi regulation in the absence and presence of bicarbonate (HCO3-); Recovery of pHi from an acute acid load; Effects of platelet-derived growth factor on baseline activity, sodium/hydrogen pump activity and HSC proliferation.

Reports on the results of a confocal microscopic analysis of intracellular pH regulation in isolated guinea pig pancreatic ducts. Confocal imaging of the cytoskeleton; Effects of secretin and carbachol on recovery of pH after intracellular acidification in the presence or absence of amiloride and bafilomycin.

Examines the modulation of L-type calcium ion channel current by extracellular pH in vascular smooth muscle cells from bovine pial and porcine coronary arteries. Effect of the changes in the concentration of the charge barrier; Mechanism of proton modulation of gating and single channel conductance.

Examines the effect of intracellular pH on the availability of vascular L-type calcium ion channels. Influence of pH on single channel conductance; Frequency of late channel reopenings; Protonation of cytosolic binding sites: Permeation of protons through surface membrane of vascular smooth muscle cells.

Investigates glucose effects on intracellular pH and intracellular free calcium, in a dose-dependent fashion. Modulation of free calcium by glucose; Cell culture; Culture preparation; Dose dependency of glucose effect; Effect of thapsigargin (TG); Magnitude of TG-induced changes in intracellular pH.

Discusses the modulation of chloride channel activity by intracellular hydrogen-ion concentration (pH) in isolated lacrimal gland acinar cells. Effects of intracellular pH on calcium activated chloride currents; Time-dependent activation at depolarizing potentials; Time-dependent inactivation at hyperpolarizing potentials.

Characterizes the expression and regulation of chloride ion fluxes in Xenopus oocytes by hydrogen-ion concentration of murine AE2 anion exchanger. Chloride/bicarbonate exchange; Optimization of AE2-associated chloride influx; Pharmacological characterizatiion of AE2.

Investigates the mechanism for potential-induced changes in intracellular pH. Nature of hydrogen ion and hydroxide ion conductance in cell membranes; Physiological significance of the potential dependence of pH; Potential-dependence of pH in nonepithelial and epithelial cells; Cellular signal transduction.

Characterizes apical calcium influx and its role on transcellular calcium reabsorption in the rabbit cortical collecting system. Variation of the electrical driving force for calcium; Effect of apical pH; Effect of intracellular pH; Involvement of an apical calcium/hydrogen exchanger.

Discusses the development of a model permitting the separate control of the apical and basolateral environments of normally oriented parietal cells and chief cells. Isolation of gastric glands; Perfusion apparatus; Optical system; Experimental protocol; Nigericin calibration.

Studies the effect of extreme pH levels on the physiology of the Australian freshwater crayfish Cherax destructor. Effects of acid exposure; Effects of alkaline exposure; Comparison on the responses of the C. destructor and its European and North American varieties to extreme pH levels.

Part II. Describes studies of the relationships between carbon dioxide transport and acid-base balance with results on hemolymph buffering capacities in arachnids. Influence of oxygen on CO2 transport and on hemolymph ion concentrations; Calculations; Gas analysis of hemolymph samples; Cold-acclimation; Gas exchange and transport.

Presents a study on the influence of transmembrane hydrogen-ion concentration (pH) gradient and membrane potential on the transport and distribution of L(+)-lactate (Lac), metabolic H+ and related parameters in rainbow trout white muscle after exhaustive exercise. Evidence for involvement of electroneutral mechanisms in lactate efflux; Perfusion.

The combined effect of Ca and pH on fish and fisheries is considered for both laboratory and field studies. It can be seen that at concentrations less than 100 μeq l, Ca can exert a significant influence on survival times of fish, and similarly in the field, the number of fishless lakes and the number of fish species found in lakes are less dependent on H concentration at low concentrations of Ca than at high Ca levels. The limited historical field data available suggest that alongside any increase there may have been in surface water acidity, Ca concentrations have also increased, and the latter may have offset to some extent the deleterious biological effects of this increased acidity. Nevertheless, details of seasonal and spatial variations in these important water quality factors will need to be considered before a full understanding of the response to acidity of a fishery can be reached. [ABSTRACT FROM AUTHOR]

Presents a study that investigated the defense of pH during acute respiratory acidosis superimposed upon chronic hypercapnia. Profile of patients who were the subject of the study; Methodology used in the study; Discussion on the results of the study.

We suggest that varicocele leads to male factor infertility by a mechanism involving underperfusion of the testis, a shortfall in glucose supply to the tissue, decreased flux through the pentose phosphate pathway, lowering of the reduced nicotinamide–adenine dinucleotide phosphate/oxidized nicotinamide–adenine dinucleotide phosphate ratio and the supply of glutathione to the antioxidant systems, increased levels of reactive oxygen species, peroxidation of spermatozoon membrane lipids, and the consequent generation of acidic degradation products and sequestering of spermine. Acidification of the seminal plasma impairs sperm motility and also inhibits most antioxidant enzymes, exacerbating the accumulation of reactive oxygen species and the resultant lowering of pH. [Copyright &y& Elsevier]

Examines the effect of cytoplasmic pH (pHin) alkalinization by membrane-permeating amines such as ammonia on the growth of Enterococcus hirae at a high pH. Effect of amine of the pHin of growing E. hirae; Effect of ammonium on cell growth; K+/H+ antiport induced pHin alkalinization.

Explores the physiological test of hydrogen-ion concentration (pH) after a competitive rowing. Physiological limit of pH in healthy humans; Concentration of lactate in venous blood; Effect of low pH on hemoglobin affinity; Acid-base balance in blood after maximal exercise.

Unacceptable meat colour scores at the time of carcass grading are associated with reduced meat quality and consumer rejection. We hypothesised that the meat colour at carcass grading would be influenced by the pH and temperature decline post slaughter, as these would be determined by animal and processing factors. Beef carcasses (n = 1512) at seven Australian processing plants were assessed, at grading, for the meat colour of the M. longissimus thoracis. Statistical modelling determined the animal, carcass and processing factors contributing to the meat colour score at carcass grading. The occurrence of unacceptably dark meat dropped from 8 to 3% when the time of grading was increased from 14 to 31 h post slaughter (P < 0.01). A high temperature at pH 6 (rigor temperature), high final pH (pH[sub F]), pasture feeding and older animals were associated with dark M. longissimus thoracis at carcass grading (P < 0.05 for all). Less than 30% of carcasses with non-compliant pH[sub F] displayed a dark non-compliant meat colour >3, indicative of an opportunity to determine the mechanism behind this pH-induced colour development and thus reduce the incidence of non-compliance. It is recommended that when there is a high occurrence of carcasses with a dark meat colour >3 that the time from slaughter to grading is checked to ensure carcasses are in full rigor at the grading point. This will assist in minimising economic penalties due to dark-coloured carcasses. Finally, animal factors, such as maturity and feeding regime also had a considerable impact on the meat colour at carcass grading. Unacceptably dark meat colour scores are a major cost to the beef industry. Beef carcasses (n = 1512) were assessed for meat colour and 10% were non-compliant for colour. The main causative factors were a short time from slaughter to grading, high final pH, low rigor temperature, older animals and pasture feeding. Attention to these factors can improve meat colour scores at grading. [ABSTRACT FROM AUTHOR]