Determination of intracellular pH and PCO2 after metabolic inhibition by fluoride and nitrilotriacetic acid

Mean intracellular pH (pHi) and PCO2 (PiCO2) have been analysed based on pH and total CO2 measurements in tissue homogenates. Tissues were sampled from undisturbed worms (Sipunculus nudus), squid (Illex illecebrosus), trout (Salmo gairdneri), toads (Bufo marinus), and rats. Homogenate metabolism was inhibited by the addition of potassium fluoride and nitrilotriacetic acid (NTA). Model calculations revealed that the influence of dilution, medium buffers, and contamination by extracellular fluids was negligible. In white muscle tissue the resulting pHi values were virtually the same as found in studies using DMO (dimethyloxazolidinedione). If large fractions of mitochondria were present (e.g. in heart muscle), DMO derived pHi values were considerably higher, probably representing overestimates. Homogenate derived pHi values are concluded to represent the effective mean pHi by taking into account pH gradients, and the volumes and buffering of cellular compartments. High time resolution and small variability make this method especially useful to assess rapid changes in pHi, e.g. in exercising animals.

Determination of intracellular buffer values after metabolic inhibition by fluoride and nitrilotriacetic acid

Non-bicarbonate buffer values have been analysed in homogenates of squid mantle muscle and toad gastrocnemius muscle using the PCO2 equilibration technique. Homogenate metabolism was inhibited by the addition of potassium fluoride and nitrilotriacetic acid. After an initial change in the concentration of organic phosphates a new metabolic equilibrium was achieved which was insensitive to pH changes during PCO2 variations. Inaccurate measurements of homogenate buffer values could, thereby, be prevented. The accumulation of inorganic phosphate during the initial metabolic shift caused an increase in homogenate buffer values. Levels of unbound inorganic phosphate, which are effective in buffering, were estimated by enzymatic analysis in homogenate ultrafiltrates. Based on the evaluation of apparent dissociation constants pK', and buffer values for fluoride and inorganic phosphate, the non-bicarbonate, non-phosphatei (i: inorganic) buffer value of the tissue was calculated. The level of free inorganic phosphate in the resting tissue was considered for an estimate of the intracellular non-bicarbonate buffer value under control conditions.

Flux-dependent increase in the stoichiometry of charge translocation by mitochondrial ATPase/ATP synthase induced by almitrine

After studying the effects of almitrine, a new kind of ATPase/ATP synthase inhibitor, on two kinds of isolated mammalian mitochondrion, we have observed that: (1) Almitrine inhibits oligomycin-sensitive ATPase; it decreases the ATP/O value of oxidative phosphorylations without any change in the magnitude of delta mu H+. (2) Almitrine increases the mechanistic H+/ATP stoichiometry of ATPase as shown by measuring either (i) the extent of potassium acetate and of potassium phosphate accumulation sustained by ATP utilisation, or (ii) the electrical charge/ATP (K+/ATP) ratio at steady-state of ATPase activity. (3) Rat liver mitochondria are at least 10-times more sensitive to almitrine than beef heart mitochondria. (4) The change in H+/ATP stoichiometry induced by almitrine depends on the magnitude of the flux through ATPase. The inhibitory effect of almitrine on ATPase/ATP synthase complex, as a consequence of such an H+/ATP stoichiometry change, is discussed.

Cell-wall polysaccharides and glycoproteins of parenchymatous tissues of runner bean (Phaseolus coccineus)

1. Polymers were solubilized from the cell walls of parenchyma from mature runner-bean pods with minimum degradation by successive extractions with cyclohexane-trans-1,2-diamine-NNN'N'-tetra-acetate (CDTA), Na2CO3 and KOH to leave the alpha-cellulose residue, which contained cross-linked pectic polysaccharides and Hyp-rich glycoproteins. These were solubilized with chlorite/acetic acid and cellulase. The polymers were fractionated by anion-exchange chromatography, and fractions were subjected to methylation analysis. 2. The pectic polysaccharides differed in their ease of extraction, and a small proportion were highly cross-linked. The bulk of the pectic polysaccharides solubilized by CDTA and Na2CO3 were less branched than those solubilized by KOH. There was good evidence that most of the pectic polysaccharides were not degraded during extraction. 3. The protein-containing fractions included Hyp-rich and Hyp-poor glycoproteins associated with easily extractable pectic polysaccharides, Hyp-rich glycoproteins solubilized with 4M-KOH+borate, the bulk of which were not associated with pectic polysaccharides, and highly cross-linked Hyp-rich glycoproteins. 4. Isodityrosine was not detected, suggesting that it does not have a (major) cross-linking role in these walls. Instead, it is suggested that phenolics, presumably linked to C-5 of 3,5-linked Araf residues of Hyp-rich glycoproteins, serve to cross-link some of the polymers. 5. There were two main types of xyloglucan, with different degrees of branching. The bulk of the less branched xyloglucans were solubilized by more-concentrated alkali. The anomeric configurations of the sugars in one of the highly branched xyloglucans were determined by 13C-n.m.r. spectroscopy. 6. The structural features of the cell-wall polymers and complexes are discussed in relation to the structure of the cell walls of parenchyma tissues.

Cytoarchitecture of the smooth muscles and pericytes of rat cerebral blood vessels. A scanning electron microscopic study

The three-dimensional cytoarchitecture of the smooth muscles and pericytes of rat cerebral blood vessels was studied by scanning electron microscopy after removing extracellular connective tissue matrices with the KOH-collagenase digestion method. The tunica media of major intracranial arteries such as the internal carotid, vertebral, basilar, and other cerebral arteries measuring more than 100 microns in outer diameter consisted of spindle-shaped smooth-muscle cells arranged circularly to the long axis of the vessel. Muscle cells at the branching points, however, showed a variety of shapes, sizes, and arrangements. As the vessel size decreased, smooth-muscle cells showed bi- or trifurcations at the cell poles. In the precapillary arterioles, smooth-muscle cells which had helically surrounded the endothelial tubes had bulging cell bodies with various cytoplasmic processes extending from the cell poles. Distinct specializations presumed to be sphincters were not found on the arteries or arterioles. Pericytes of the capillary had become extended along the vessel axis, having fusiform cell bodies with longitudinally oriented long cytoplasmic processes. Cells located periendothelially in the venules and veins were stellate in shape with many cytoplasmic processes which were interwoven to form complicated cellular networks around the endothelial tube.

Toxicity and carcinogenicity of potassium bromate--a new renal carcinogen

Potassium bromate (KBrO3) is an oxidizing agent that has been used as a food additive, mainly in the bread-making process. Although adverse effects are not evident in animals fed bread-based diets made from flour treated with KBrO3, the agent is carcinogenic in rats and nephrotoxic in both man and experimental animals when given orally. It has been demonstrated that KBrO3 induces renal cell tumors, mesotheliomas of the peritoneum, and follicular cell tumors of the thyroid. In addition, experiments aimed at elucidating the mode of carcinogenic action have revealed that KBrO3 is a complete carcinogen, possessing both initiating and promoting activities for rat renal tumorigenesis. However, the potential seems to be weak in mice and hamsters. In contrast to its weak mutagenic activity in microbial assays, KBrO3 showed relatively strong potential inducing chromosome aberrations both in vitro and in vivo. Glutathione and cysteine degrade KBrO3 in vitro; in turn, the KBrO3 has inhibitory effects on inducing lipid peroxidation in the rat kidney. Active oxygen radicals generated from KBrO3 were implicated in its toxic and carcinogenic effects, especially because KBrO3 produced 8-hydroxydeoxyguanosine in the rat kidney. A wide range of data from applications of various analytical methods are now available for risk assessment purposes.

Activity of cathepsin D as affected by chemical and physical dry-curing parameters

The effect of curing agents (nitrate, glucose, ascorbic acid and chloride) and physical parameters (temperature, water activity and pressure) on porcine muscle cathepsin D has been studied. Chloride (in the assayed range 0 to 75 g Cl-/L) showed a strong inhibitory effect. Nitrate (in the assayed range 0 to 800 mg/L) and high concentrations of ascorbic acid (4 to 8 g/L) slightly inhibited cathepsin D. However, its activity increased when glucose was added up to 4 g/L. Cathepsin D activity was maximal when incubated at 33 to 53 degrees C, was affected by a decrease in water activity and unaffected by pressure.

A comparison of calcofluor white, potassium hydroxide, and culture for the laboratory diagnosis of superficial fungal infection

A total of 207 skin scrapings were prospectively studied using potassium hydroxide (KOH), calcofluor white (CW), and culture to determine the clinical usefulness of each microscopic method. For dermatophytes (prevalence 13.2%), CW had a sensitivity of 92% and a specificity 95%, giving a positive predictive value of 74% and negative predictive value of 99%. KOH had a sensitivity of 88% and a specificity of 95%, giving a positive predictive value of 73% and a negative predictive value of 98%. CW was simple, rapid, and easy to read. For dermatophyte infection, CW results are as useful as KOH results.

[Preventive dentistry in France]

In France, oral prevention has recently progressed in various aspects of dental caries prophylaxis which is reviewed in this paper. A better knowledge of dental caries prevalence has been obtained at a national level and the French Government authorized in October 1985 salt fluoridation for a period of 5 years which in addition to other means of caries prevention such as fluoridated toothpastes and various local and topical procedures has increased the potentials of fluoride use in France. In addition a larger use of fissure sealants has been encouraged. It is hoped that the introduction of salt fluoridation in France will reduce the caries incidence to a DMFT not more than 3 for the 12 year old children thus fulfilling the WHO goals for oral health in the year 2000.

[The stress process of hot-dry climatic conditions in a simulation chamber]

On the basis of investigations in the potash mining industry of GDR were formulated the starting conditions for experiments in a simulation chamber. The results of the experiments in a climatic chamber to complex dry-hot mining climatics are published and compared with hitherto existing results. Comprehensions to work load limits for dry-hot climatic conditions are established.

Bovine and mouse serum beta inhibitors of influenza A viruses are mannose-binding lectins

Normal bovine and mouse sera contain a component, termed beta inhibitor, that inhibits the infectivity and hemagglutinating activity of influenza A viruses of the H1 and H3 subtypes. To investigate the nature of the interaction of beta inhibitors with influenza A viruses we isolated a mutant of the virus Mem71H-BelN (H3N1) that could grow in the presence of bovine serum. The mutant virus was resistant to hemagglutination inhibition by mouse serum as well as by bovine serum and had undergone changes in the receptor-binding and the antigenic properties of its hemagglutinin (HA) molecule. Sequence analysis of the HA genes of parent and mutant viruses revealed a single nucleotide change in the mutant, resulting in the substitution Thr----Asn at residue 167 of the HA1 chain of HA. This change leads to loss of the potential glycosylation site Asn-165-Val-166-Thr-167 at the tip of the HA spike, which in viruses of the H3 subtype is known to bear a high-mannose (type II) carbohydrate side chain N-linked to Asn-165. The association of beta inhibitor resistance with loss of this carbohydrate side chain suggested that beta inhibitors may be lectins. In support of this hypothesis, treatment of the beta inhibitor-sensitive parent virus Mem71H-BelN with periodate converted it to the resistant state. Furthermore, the inhibitory activity of both bovine and mouse sera for the parental virus was abrogated by D-mannose. We conclude that the beta inhibitors in bovine and mouse sera are mannose-binding lectins that inhibit hemagglutination and neutralize virus infectivity by binding to carbohydrate at the tip of the HA spike, blocking access of cell-surface receptors to the receptor-binding site on HA.

Paradoxical effect of bicarbonate on cytoplasmic pH

The effect of an abrupt rise in bicarbonate concentration on cytoplasmic pH was studied in human platelets suspended in a Tyrode's buffer. Addition of bicarbonate raised extracellular pH but simultaneously caused pronounced cytoplasmic acidification. This effect may be due to combination of bicarbonate with hydrogen ions in extracellular fluid to form carbonic acid, which is converted by carbonic anhydrase to water and carbon dioxide. Bicarbonate ions do not diffuse rapidly across cell membranes, whereas carbon dioxide is highly diffusible and can combine with water in the cytoplasm, forming carbonic acid and reducing the intracellular pH. In accord with this explanation cytoplasmic acidification by bicarbonate was antagonised by acetazolamide (an inhibitor of carbonic anhydrase). Cytoplasmic acidification could contribute to adverse effects of intravenous sodium bicarbonate in patients with severe acidaemia. These findings add weight to the body of opinion that such treatment is both illogical and dangerous.

Stomatocytic or discoidal erythrocyte ghosts containing only spectrin

We extracted Triton-treated erythrocyte ghosts with 2 M KCl (Triton/KCl/ghosts), and then with 1.2 M KBr at pH 5.5 (Triton/KCl/KBr ghosts). Triton/KCl/KBr ghosts were very similar in shape to untreated ghosts, Triton ghosts and Triton/KCl ghosts under a phase-contrast microscope at various pH vales and salt concentrations, despite having lost most of their phospholipids and proteins, except for spectrin. Negatively stained Triton ghosts, Triton/KCl ghosts and Triton/KCl/KBr ghosts appeared similar to each other, but the regularity of the spectrin network structure decreased somewhat in that order. Triton/KCl/KBr ghosts were stabilized by adding both actin and band 4.1, but not by adding either alone. These and previous findings strongly suggest that the spectrin network is visible and the simplest inframembrane structure.

Insulin stimulates the activity of a protamine kinase in isolated rat hepatocytes

Treatment of isolated rat hepatocytes with 10-100 nM insulin for 5-10 min increased by about 2-fold the activity of a protamine kinase which exhibited properties similar to those of a protamine kinase from bovine kidney (Damuni, Z., Amick, G. D., and Sneed, T. R. (1989) J. Biol. Chem. 264, 6412-6416). Half-maximal increase in protamine kinase activity occurred at about 1 nM insulin. This effect of insulin was detected only when 25 mM NaF or 50 mM KPO4 were included in the homogenization buffers and was not prevented by preincubation of the hepatocytes with 10 microM cycloheximide. Insulin stimulation of protamine kinase was maintained following chromatography of extracts on protamine-agarose, DEAE-cellulose, and Sephacryl S-200 gel filtration. The apparent Mr of the protamine kinase from control and insulin-treated hepatocytes was 45,000 as estimated by gel permeation chromatography. Experiments utilizing partially purified protamine kinase from control and insulin-treated hepatocytes indicated that insulin did not affect the apparent Km for protamine, Mg2+, or ATP, but increased the Vmax for the protamine kinase reaction by 1.6-2-fold. Incubation with the catalytic subunit of protein phosphatase 2A completely inactivated the protamine kinase from control and insulin-treated cells. The results indicate that the insulin-stimulated increase in protamine kinase activity may be due to a covalent modification, possibly phosphorylation, of the protamine kinase.

[Disordered phosphorus metabolism and its correction in the acute period of severe craniocerebral trauma]

Marked hypophosphatemia was discovered in 78 patients in the acute period of severe craniocerebral injury. It led to a decrease of the level of 2,3-diphosphoglycerate (2,3 DPG) and ATP in the red cells. The reduced ATP level in the red cells was one of the causes of reduced Ca2+ ATPase activity in their membranes. Intravenous infusion of 6.8% potassium dihydrophosphate solution prevented the development of hypophosphatemia and reduction of the content of 2,3 DPG and ATP in the red cells and Ca2+ ATPase activity in their membranes, which facilitated improvement in the course of acute posttraumatic period in patients with severe craniocerebral injury and decrease of mortality.

Active and passive chloride transport by the rabbit cortical collecting duct

Dietary K intake has been shown to influence solute flux in the cortical collecting duct (CCD). We recently observed active Cl secretion by the CCD when rabbits were fed a K-rich diet. The present studies examined two different methods of K loading (KHCO3 or KCl) on net Cl flux (JNet Cl), active Cl flux (JA Cl), and passive Cl flux (JP Cl) by the rabbit CCD. These two methods of K loading were compared with a low-K diet (control or NaHCO3 diet) that had the same anion composition as the KHCO3 diet (Na for K substitution). In the low-K group there was neither significant net Cl transport nor active Cl secretion. Increasing dietary K content (KHCO3 group) resulted in significant net Cl secretion (JNet Cl = -26.3 +/- 9.3 pmol.mm-1.min-1). Moreover, K secretion was significantly greater (23.8 +/- 4.3 pmol.mm-1.min-1) and transepithelial voltage (VT) was more lumen negative (-14.8 +/- 5.9 mV) compared with the low-K group (P less than 0.05). Consequently, there was both significant passive Cl absorption and significant active Cl secretion. In the KCl group there was significant net Cl absorption (JNet Cl = 17.2 +/- 5.1 pmol.mm-1.min-1, P less than 0.05 vs. low-K diet). However, Na absorption significantly exceeded JNet Cl (JNet Na = 42.0 +/- 7.2 pmol.mm-1.min-1, P less than 0.01), and this group also exhibited the most lumen-negative voltage (VT = -35.4 +/- 5.4 mV).(ABSTRACT TRUNCATED AT 250 WORDS)

Role of the source of phosphate salt in improving the mineral balance of parenterally fed low birth weight infants

Because the monobasic potassium phosphate salt (monobasic) improves the solubility of calcium and phosphorus in amino acid plus dextrose solutions, compared with the current mixtures of monobasic plus dibasic salts (dibasic), we tested the bioavailability and clinical effects of monobasic in 16 parenterally fed low birth weight infants at standard (n = 8) and high levels (n = 8) of mineral intakes. A constant infusion of macronutrients and vitamin D was provided in a crossover design of two four-day periods. With standard intakes of calcium (35 mg/kg/day, 0.9 mmol/kg/day) and phosphorus (30 mg/kg/day, 1 mmol/kg/day), there was no difference between monobasic and dibasic regimens on balance data or plasma biochemical monitoring (calcium, phosphorus, pH, carbon dioxide pressure, base excess, 1,25-dihydroxyvitamin D, 25-hydroxyvitamin D). With the use of the monobasic regimen, the mineral intakes were doubled without precipitation in the infusate: calcium, 70 mg/kg/day (1.8 mmol/kg/day), and phosphorus, 55 mg/kg/day (1.7 mmol/kg/day). This led to increased apparent retention of both calcium (63 +/- 5 mg/kg/day, 1.58 +/- 0.12 mmol/kg/day) and phosphorus (52 +/- 4 mg/kg/day, 1.67 +/- 0.14 mmol/kg/day) compared with that for standard levels of mineral intake. The improvement of calcium-phosphorus balance was accompanied by more severe calciuria (9 +/- 2 mg/kg/day, 0.2 +/- 0.05 mmol/kg/day) and by metabolic compensation for an increased acid load. In addition to the possibility of exceeding the buffering capacity of the infant, this relative acidosis could also be evidence of improved bone mineralization.

Characterization of tonoplast-enriched vesicles isolated by gradient density fractionation of suspension-cultured cells

A tonoplast-enriched microsomal fraction was isolated from Catharanthus roseus cells. It was characterized by structural and functional criteria. This fraction presented a homogeneous size distribution as shown by quasi-elastic light scattering and a homogeneous density on self-generated gradients of Percoll. The mean diameter of the vesicles was estimated to be 0.30 micron and the buoyant density around 1.04 g/ml. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of its polypeptide pattern was in good agreement with the one obtained for tonoplast purified from isolated vacuoles. According to enzymatic assays and inhibition tests, this fraction possessed pyrophosphate and ATP-dependent proton pumps and very low contamination by submitochondrial particles, endoplasmic reticula and Golgi membranes. In light of our previous published results on tonoplast purified from isolated vacuoles, the very low extent of AMP hydrolysis by the microsomal fraction is interpreted as supplementary proof in favor of a tonoplast-enriched fraction.

Reduction of anthralin-induced inflammation by application of amines

Twenty-two primary, secondary, and tertiary amines were studied to determine whether they could reduce anthralin-induced inflammation. Amine solutions of 0.18 mol/L were applied after anthralin application to normal forearm skin. Inflammation was measured with the use of Harpenden calipers by the increase in skin thickness at 48 hours. Inflammation was reduced by 66% to 95% with the use of nine different amines. There was no overall correlation between the inhibiting effect and either amine basicity or octanol/water partition coefficient. However, within each of the series of primary, secondary, and tertiary alkylamines there appeared to be some correlation between inhibitory effect and alkyl chain size, which may reflect differences in transdermal flux. Some of these amines are used in cosmetics and skin cleansers and could help reduce the inflammation that accompanies anthralin therapy for psoriasis.

Acid-base state of the preterm infant and the formulation of intravenous feeding solutions

An acidic intravenous source of phosphorus (Addiphos) was compared with dipotassium hydrogen phosphate in 25 preterm infants to study acid-base state. Eight infants were given either Addiphos or dipotassium hydrogen phosphate alternately for 48 hour periods and similar amounts of calcium and phosphorus were delivered. There were no significant differences in calcium and phosphorus intake, calcium and phosphate plasma concentrations, or acid-base state between study periods on the two solutions. Seventeen infants were given the two solutions alternately for 72 hour periods; Addiphos was used to increase the amounts of calcium and phosphorus being delivered. Calcium and phosphorus intake was decreased on dipotassium hydrogen phosphate, but Addiphos significantly increased calcium and phosphorus intake and plasma calcium and phosphate concentrations. It also lowered the pH of the urine and raised the titratable acidity. Acid-base state, however, was not significantly different. It is therefore possible to increase intake of calcium and phosphorus in preterm infants without causing a significant metabolic acidosis.

Superficial fungal infections. A practical guide for primary care physicians

Clinicians who establish a proper diagnosis should have little difficulty managing dermatophyte infections. Diagnosis can be confirmed by direct microscopic examination with a potassium hydroxide preparation or by culture with the dermatophyte test medium. Safe, reliable antifungal therapy is available. Treatment will be more effective if antifungal therapy is not prescribed until fungal organisms have been identified and if topical steroids are not prescribed until fungal organisms have been excluded.

[Functional and metabolic effects of nicardipine on ischemic rat hearts with multidose potassium cardioplegia]

This study was undertaken to assess the effect of a calcium antagonist, nicardipine (N), added in a cardioplegic solution on the ischemic myocardium. Isolated rat hearts were perfused with oxygenated Krebs Ringer Bicarbonate (KRB) solution by Langendorff's perfusion method and were subjected to 2 hours of ischemic arrest at 30 degrees C with multidose cardioplegia (every 30 min, for 5 min) and a subsequent 60 min of reperfusion. HR, LVP, coronary flow and oxygen tension of coronary effluent were monitored. Oxygen saturation of intracellular myoglobin and redox state of mitochondrial cytochrome aa3 in the myocardial cell were continuously measured throughout studies by a spectrophotometer. Oxygenated crystalloid cardioplegic solution (KRB) containing 25 mM of potassium was used. 40 rats were divided into 4 groups (10 rats each) according to the concentration of N (none, 0.5, 1 and 2 mg/L) in fully oxygenated potassium cardioplegic solution (PO2: 601 +/- 31 mmHg). The percent recovery of pressure-rate product after reperfusion was compared in each group and the optimal concentration of N was found to be 1 mg per liter of cardioplegic solution. No significant difference was found between Group Ia (N = 0 mg/L) and Group Ib (N = 1 mg/L) in metabolic or hemodynamic recovery after reperfusion. In other experiments, 40 rats in Group IIa (N = 0 mg/L, n = 20) and Group IIb (N = 1 mg/L, n = 20) received 10 ml of poorly oxygenated cardioplegic solution (PO2: 215 +/- 10 mmHg) on each reinfusion followed by a 25 min interval of ischemic arrest. The index of oxygen utilization, MVO2/pressure-rate product after reperfusion was significantly lower in Group IIb than in Group IIa (p less than 0.05). The results show that the addition of N (1 mg/L) to the cardioplegic solution preserved a more aerobic state (higher intracellular oxygen level) in the myocardium by further suppressing myocardial oxygen demand during the ischemic period which resulted in better myocardial protection. Therefore, it is concluded that the addition of N to the cardioplegic solution enhances myocardial preservation during myocardial ischemia.

Calcium and phosphorus solubility in neonatal intravenous feeding solutions

The limited solubility of calcium and phosphorus in standard parenteral nutrition formulations has restricted the ability to provide sufficient minerals to preterm infants to prevent substrate deficient metabolic bone disease. We determined the solubility limits of calcium and phosphorus in a total of 160 formulations under carefully controlled conditions. By increasing the concentrations of dextrose, amino acids, and by using Addiphos instead of 8.7% dipotassium hydrogen phosphate as the phosphorus source, higher concentrations of both calcium and phosphorus were held in solution. This should permit the delivery of increased concentrations of these minerals at rates which approximate fetal accretion.