Multiple parameters for the comprehensive evaluation of the susceptibility of Escherichia coli to the silver ion

The susceptibility of Escherichia coli B to the antibacterial activity of silver ions was measured in terms of the initial inhibitory concentration, complete inhibitory concentration, postagent effect for bacteriostatic susceptibility, minimum bactericidal concentration, maximum tolerant concentration, and log killing time for bactericidal activity. At a concentration of 9.45 M and an inoculum size of 10 CFU ml, silver caused growth delay of E. coli; at a concentration of 18.90 M, silver completely inhibited bacterial growth. Prolonged postagent effects ranged between 1.5 and 12 h at 0.75 x the initial inhibitory concentration, 1.0 x the initial inhibitory concentration, and 1.5 x the initial inhibitory concentration of the silver ion. One log-unit of viable bacterial population size was lost every 30 min at the minimum bactericidal concentration of the silver ion. Silver tolerance was determined as 20 times the initial inhibitory concentration with 48 h of exposure. This study presents an evaluative model as a reference for the quantitative analysis of the susceptibility of bacteria to silver ions. © Rapid Science 1998.     

Free amino acids in the spinal cord and ganglia of dogs after ligation of the abdominal aorta

The authors studied the effect of 40 min and 6 days occlusion of the abdominal aorta on the aspartate [Asp], glutamic acid [Glu], glutamine [Gln], glycine [Gly] and alanine [Ala] concentration in both parts of the grey matter of the lumbosacral cord, in the spinal ganglia and along the dorsal fasciculi. After 40 min ischaemia, an increase was found in the Glu, Gln, Gly and Ala concentration in the dorsal part of the grey matter and in the Glu, Gly and Ala concentration in the spinal ganglia. In the ventral part of the grey matter only the Ala concentration was increased. After 6-day ligation, the Asp and Gly concentration fell in the ventral horns, while the Gly concentration rose in the dorsal horns. The Ala and Asp concentration in the spinal ganglia rose. After this interval the Asp and Glu concentration also rose in the fasciculus gracilis. The Ala/Glu concentration ratio showed the most pronounced increase in the central horns of the grey matter.     

Effect of cold exposure on the concentration of triglyceride in the liver of the rat

The aim of the present study was to examine an effect of cold exposure on the concentration of triglycerides (TG) in the rat's liver. The rats were divided into the following groups: control, fed with oil, treated with hydrocortisone, fed with oil and treated with hydrocortisone, treated with noradrenaline. The rats exposed to cold were kept in wire cages (one rat in one cage) in the cold room at temperature +2 degrees C. They had free access to food (pellet diet for rodents) and water. In the control group the exposure to cold increased mildly (though significantly) the TG concentration after 1 and 3 h and had no effect after 2 and 24 h. It did not affect the concentration of plasma free fatty acids (FFA). At room temperature feeding with oil (2 ml/100 g of body weight) alone, and combined with hydrocortisone treatment (5 mg/100 g of body weight) as well as treatment with noradrenaline (0.1 mg/100 g of body weight) had no effect on the liver TG concentration, although the concentration of plasma FFA was increased. Exposure to cold for 3 h increased markedly the liver TG concentration in each of those groups. It is concluded that exposure to cold elicits a mechanism, which in the presence of elevated plasma FFA concentration induces accumulation of TG in the liver.     

Distension of the pulmonary vein - atrial junctions and plasma vasopressin in the chloralose-anaesthetized dog

The effects of localized distension of the pulmonary vein - left atrial junctions on plasma arginine vasopressin (AVP) have been examined in chloralose anaesthetized dogs. Pulmonary vein distension caused an increase in heart rate and a decrease in plasma AVP concentration. Cooling the vagosympathetic nerves to 10 degrees C caused an increase in arterial pressure and plasma AVP concentration and prevented the changes in heart rate and plasma AVP concentration caused by pulmonary vein distension. Cooling the vagus nerves to 16 degrees C did not change heart rate, arterial pressure, or plasma AVP concentration but significantly reduced the changes in heart rate and plasma AVP concentration caused by pulmonary vein distension. Propranolol (0.5 mg/kg) decreased heart rate and prevented the increase in heart rate associated with pulmonary vein distension but did not abolish the decrease in plasma AVP concentration. It is concluded that distension of the pulmonary vein - left atrial junctions causes a decrease in plasma AVP concentration by stimulating atrial receptors with myelinated afferent fibres. The decrease in plasma AVP concentration is not secondary to the reflex changes in heart rate caused by pulmonary vein distension.     

Optimization of the culture medium composition for the antibody response of mouse spleen cells

Summary The Mishell-Dutton culture system for in vitro primary antibody response of mouse spleen cells was used to optimize the amino acid composition of RPMI 1640 media. Each of the 20 amino acids was tested over a broad range of concentrations always leaving the remaining 19 amino acids unaltered (i.e. at the formula recommended concentration). In several instances, higher plaque-forming cell responses were obtained with an amino acid concentration that was either higher or lower than that recommended: (a) the optimum concentration for valine, glutamine, and lysine lies considerably above the recommended one, (b) the optimum concentration for leucine as well as for several other amino acids lies below the recommended concentration, and (c) the optimum concentration for arginine corresponds exactly to the recommended concentration. The second round of optimization, i.e. combining of two conditions that individually yielded an improved response often caused a decrease of response. The possibility is discussed that for an optimal response a ratio of two or several amino acids rather than the absolute concentration of any one amino acid is of importance. The Basel Institute for Immunology was founded and is supported by F. Hoffman-La Roche & Co., Ltd.     

Substance P affects the GABAergic system in the hypothalamo-pituitary axis

In the present work we examined the effect of the neutralization of endogenous substance P by the administration of an anti-substance P serum (ASPS) on GABA concentration in the anterior pituitary in hyperprolactinemic conditions induced by 5-hydroxytryptophan or by grafting anterior pituitaries. ASPS reduced the increase in the anterior pituitary GABA concentration induced by hyperprolactinemia. In vitro experiments showed that substance P inhibited K⁺-evoked GABA efflux from hypothalamic fragments and decreased GABA concentration in the anterior pituitary but ASPS increased it. Our results demonstrate that substance P modifies hypothalamic GABA release and anterior pituitary GABA concentration and suggest that an interaction exists between substance P and GABA.     

The effect of ATP on the order and the mobility of lipids in the bovine erythrocyte membrane

The order and the mobility of the lipids in the membrane were measured by the ESR method for the erythrocytes with both normal and modified intracellular concentration of ATP. The lipid order did not depend on the ATP level, but the lipid mobility was affected by the intracellular ATP concentration. The lipid mobility was higher in the cells with a larger concentration of ATP.     

Influence of the aminopeptide concentration on the growth of Haemophilus influenzae, type b, and the synthesis of its capsular polysaccharide

The influence of the aminopeptide concentration on the growth of H. influenzae b culture and the synthesis of H. influenzae b capsular polysaccharide was determined. The maximum amount of capsular polysaccharide was accumulated at the concentration of aminopeptide in the culture fluid reaching 50 ml/l. An increase in the aminopeptide concentration led to a decreased amount of synthesized polysaccharide and an increased amount of biomass. The decrease of the aminopeptide concentration to 10 ml/l resulted in decreased amounts of both biomass and synthesized polysaccharide.     

Effect of triathlon competition on the content of various hormones and the energy substrate of the blood

The effect of triathlon (3.8 km swimming, 180 km biking, 42 km running) and of its short variant (1.5 km swimming, 42 km biking, 14 km running) was studied in 7 and 14 well-trained men, respectively. The level of plasma glucose, total cholesterol, HDL, LDL did not change significantly during the competition. FFA concentration increased significantly (by 439 and 61%, respectively). Triglycerides concentration decreased during the prolonged variant. Both variants of triathlon caused a pronounced rise in the cortisol level and moderate increase in somatotropin and progesterone levels. Testosterone concentration increased during a short variant and decreased during a prolonged one. Insulin and C-peptide levels decreased. All those changes in hormones concentration are consistent with an increased lipolytic activity and, may be, with increased glycolytic activity (maintenance of the normal glucose concentration in blood). The rise in the aldosterone level reflects the homeostatic activity in maintaining electrolyte balance.     

Interpreting the carboxyhaemoglobin concentration in fetal cord blood

We calculated the fetal-to-maternal carboxyhaemoglobin concentration ratio in 19 mother-infant pairs at the time of term delivery. Mothers, who had a less than 10% drop in their carboxyhaemoglobin concentration during labour, had an average ratio of 1.40 +/- 0.19. For mothers whose carboxyhaemoglobin concentrations dropped by 10% or more during labour, the average fetal-to-maternal carboxyhaemoglobin concentration ratio was 1.83 +/- 0.48. There was a strong correlation (r = 0.82) between the percent change in maternal carboxyhaemoglobin concentration during labour and the fetal-to-maternal carboxyhaemoglobin concentration ratio at the time of delivery. We conclude that increased CO elimination during labour may be accompanied by rapid changes in the maternal carboxyhaemoglobin concentration, leading to a spuriously high fetal-to-maternal carboxyhemoglobin concentration ratio at the time of delivery.     

Characterization of the changes in the state of aggregation induced by ligand binding in the hemoglobin system of a primitive vertebrate, the hagfish Eptatretus cirrhatus

Hemoglobin (Hb) from the hagfish, Eptatretus cirrhatus, is composed of subunits of approx. 20,000 mol. wt. Aggregation of the deoxy subunits occurred, particularly at low pH and at high protein concentration. Oxygen equilibrium studies indicated slight cooperativity and the presence of a small, phosphate-independent Bohr effect. Equilibrium properties were protein concentration dependent indicating an oxygen-linked dissociation in the millimolar concentration range. Kinetic studies indicated a dimer to monomer transition in the micromolar concentration range. The ligand-binding character of hagfish Hb was similar to that of lampreys, but was governed by different kinetic and equilibrium parameters.     

Estimation of the cutoff value of vitamin D: the Dong-gu study

Background

Vitamin D plays an essential role in bone health and growth, but the optimal serum 25-hydroxyvitamin D (25(OH)D) concentration is not known. This study was performed to investigate the optimal 25(OH)D concentration in regard to parathyroid hormone (PTH) concentration in the Korean general population aged 50 years or older.

Findings

The study population consisted of 8,857 subjects (3,545 men and 5,312 women) who participated in the baseline survey of the Dong-gu study, conducted in Korea between 2007 and 2010. Serum 25(OH)D and PTH concentrations were measured by chemiluminescent microparticle immunoassay. The optimal 25(OH)D concentration was estimated by using nonlinear regression model. Our data show that PTH concentration reached a theoretical plateau at 38.2 pg/ml and corresponding 25(OH)D concentration was 21.1 ng/ml in men and PTH concentration at 42.9 pg/ml and 25(OH)D concentration at 13.8 ng/ml in women.

Conclusions

These results indicate that, for Korean general population aged 50 years or older, the optimal 25(OH)D concentration is 21.1 ng/ml in men and 13.8 ng/ml in women.     

The ER to Golgi Interface is the Major Concentration Site of Secretory Proteins in the Exocrine Pancreatic Cell

By using quantitative immuno-electron microscopy of two-sided labeled resin sections of rat exocrine pancreatic cells, we have established the relative concentrations of the secretory proteins amylase and chymotrypsinogen in the compartments of the secretory pathway. Their total concentration over the entire pathway was ∼ 11 and ∼ 460 times, respectively. Both proteins exhibited their largest increase in concentration between the endoplasmic reticulum and cis -Golgi, where they were concentrated 3–4 and 50–70 times, respectively. Over the further pathway, increases in concentration were moderate, albeit two times higher for chymotrypsinogen than for amylase. From trans -Golgi to secretory granules, where the main secretory protein concentration is often thought to occur, relatively small concentration increases were observed. Additional observations on a third secretory protein, procarboxypeptidase A, showed a concentration profile very similar to chymotrypsinogen. The relatively high concentration of amylase in the early compartments of the secretory route is consistent with its exceptionally slow intracellular transport. Our data demonstrate that secretory proteins undergo their main concentration between the endoplasmic reticulum and cis -Golgi, where we have previously found concentration activity associated with vesicular tubular clusters (Martínez-Menárguez JA, Geuze HJ, Slot JW, Klumperman J. Cell 1999; 98: 81–90).     

High dietary sodium chloride and body temperature in the domestic fowl and the Glaucous-winged gull

Arad and Skadhauge (1986) correlated plasma sodium to calcium ratio and body temperature in domestic fowl (Gallus domesticus) during increased dietary sodium chloride intake which increased plasma sodium concentration. During acclimation to high dietary NaCl, body temperature should increase in proportion to the increase in plasma sodium concentration, and body temperature should increase less in gulls than in chickens because salt gland secretion of NaCl by gulls should prevent elevation of plasma sodium concentration. Plasma osmolality, plasma sodium concentration, plasma concentrations of total calcium and ionized calcium, and body temperature and panting threshold were measured in domestic roosters and Glaucous-winged gulls before and after exposure to high NaCl diets. Gull body temperature (40.4±0.2 °C) increased significantly (PM0.05) during salt acclimation. Rooster body temperature (41.0±0.2 °C) did not increase significantly. Plasma sodium concentration increased in gulls (5.4±0.5%, P<0.01) and was correlated with body temperature (r=0.497, P<0.05); the 3.8±1.0% increase in plasma sodium concentration in roosters (P<0.01) was not, suggesting that change in body temperature might be a response to the magnitude of increase in plasma sodium concentration. Plasma ionized calcium concentration increased by 12.9±4.6% (P<0.01) in gulls and by 5.3±1.0% (P<0.01) in roosters. Plasma sodium concentration was correlated with calcium ion concentration in both gulls (r=0.635, P<0.05) and roosters (r=0.664, P<0.05). In neither species were ratios of sodium to total calcium plasma concentration or sodium to ionized calcium concentration altered or related to body temperature. Panting threshold increased significantly in roosters following salt acclimation, but not in gulls due to high variability in response. The increase in gull plasma sodium concentration was small compared to previously reported (Saxena 1976; Denbow and Edens 1980, 1981; Maki et al. 1988) increases in hypothalamic and intraventricular sodium concentration following infusion of Na⁺, yet the effect on body temperature was similar in both types of studies. This suggests that sodium may have peripheral effects that augment the central effects imposed by altered hypothalamic interstitial sodium and calcium concentration.Abbreviations [Ca]_p1 total calcium concentration in plasma - [Ca²⁺] ionized calcium concentration in plasma - [Cl]_p1 chloride concentration in plasma - f respiratory frequency - Hct hematocrit - [K]_p1 potassium concentration in plasma - [Na]_p1 sodium concentration in plasma - osm_p1 plasma osmolality - PT panting threshold - T _a ambient temperature - T _b body temperature - V _t tidal volume     

Measurement of the Concentration of the Active Centers of Ribulose-1,5-bisphosphate Carboxylase/Oxygenase in vivo

Methods for in vivo measurement of the concentration of the reactive centers of ribulose-1,5,-bisphosphate carboxylase/oxygenase (Rubisco) are suggested that are based on saturation of the active centers with RuBP and determination of the concentration of the Rubisco–RuBP complex. The total concentration of potentially reactive centers is calculated from the dependence of the concentration of this complex on CO₂ concentration at a steady-state photosynthetic rate with further extrapolation of the carbon dioxide dependence curve to a zero CO₂ concentration. The concentration of centers that possessed a catalytic activity under given environmental conditions was measured after transferring leaves having a steady-state photosynthetic rate into a medium devoid of CO₂ and O₂. This procedure ensured the saturation of the carboxylation centers with RuBP. The carboxylation rates were measured during a short-term exposure to ¹⁴CO₂, and the concentration of the complex was calculated using the values of CO₂ concentration during the exposure time, as well as the carboxylation rate and constant. Rubisco activity was found to decrease at elevated CO₂ concentrations due to a lower concentration of catalytically active enzyme centers.     

BMI Is the Main Determinant of the Circulating Leptin in Women after Vertical Banded Gastroplasty

Objective: To assess the main determinant of serum leptin concentration changes in morbidly obese patients treated by banded vertical gastroplasty. Research Methods and Procedures: Serum leptin and insulin concentrations, insulin resistance, BMI, body weight, and body fat mass in 18 obese women and 8 obese men treated by vertical banded gastroplasty were studied. Lean women and men subjects were used as controls. Results: Before surgery, serum leptin and insulin concentrations and insulin resistance index were significantly higher in morbidly obese patients than in control subjects. BMI, body fat mass, and serum triacylglycerol concentrations were also significantly higher in obese than in lean subjects. All of these parameters gradually decreased during 50 weeks after surgery. Univariate regression analysis displayed significant correlations between the following: serum leptin concentration and BMI (and body fat mass), serum leptin concentration and serum insulin concentration, and serum leptin concentration and insulin resistance index. Multivariate regression analysis indicated that only BMI was independently correlated with the decrease in serum leptin concentration. Discussion: Obtained data suggest the following: 1) vertical banded gastroplasty causes reduction of body weight, serum leptin and insulin concentration, insulin resistance, and serum triacylglycerol concentration; and 2) BMI is the main determinant of the circulating leptin concentration in morbidly obese women after anti‐obesity surgery.     

The mechanism by which ethanol decreases the concentration of fructose 2,6-bisphosphate in the liver.

The intragastric administration of ethanol to fed rats caused in their liver, within about 1 h, a 20-fold decrease in the concentration of fructose 2,6-bisphosphate, an activation of fructose 2,6-bisphosphatase, an inactivation of phosphofructo-2-kinase but no change in the concentration of cyclic AMP. Incubation of isolated hepatocytes in the presence of ethanol caused a rapid increase in the concentration of sn-glycerol 3-phosphate and a slower and continuous decrease in the concentration of fructose 2,6-bisphosphate with no change in that of hexose 6-phosphates. There was also a relatively slow activation of fructose 2,6-bisphosphatase and inactivation of phosphofructo-2-kinase. Glycerol and acetaldehyde had effects similar to those of ethanol on the concentration of phosphoric esters in the isolated liver cells. 4-Methylpyrazole cancelled the effect of ethanol but reinforced those of acetaldehyde. High concentrations of glucose or of dihydroxyacetone caused an increase in the concentration of hexose 6-phosphates and counteracted the effect of ethanol to decrease the concentration of fructose 2,6-bisphosphate. As a rule, hexose 6-phosphates had a positive effect and sn-glycerol 3-phosphate had a negative effect on the concentration of fructose 2,6-bisphosphate in the liver, so that, at a given concentration of hexose 6-phosphates, there was an inverse relationship between the concentration of fructose 2,6-bisphosphate and that of sn-glycerol 3-phosphate. These effects could be explained by the ability of sn-glycerol 3-phosphate to inhibit phosphofructo-2-kinase and to counteract the inhibition of fructose 2,6-bisphosphatase by fructose 6-phosphate. sn-Glycerol 3-phosphate had also the property to accelerate the inactivation of phosphofructo-2-kinase by cyclic AMP-dependent protein kinase whereas fructose 2,6-bisphosphate had the opposite effect. The changes in the activity of phosphofructo-2-kinase and fructose 2,6-bisphosphatase appear therefore to be the result rather than the cause of the decrease in the concentration of fructose 2,6-bisphosphate.     

Copper concentration in plants and in the rhizosphere as influenced by the iron status of tomato (Lycopersicon esculentum L.)

Changes of metal concentration that occur in the rhizosphere may arise from several processes including variation in the concentration of complexing ligands, pH or redox potential that can be influenced by the Fe status of the plant. The aim of this study was to assess for both acidic and calcareous, Cu-contaminated soils how Cu concentration in plants and in the rhizosphere was affected by the Fe status of a strategy I plant species. The change of soil solution pH, total solution Cu concentration and soil redox potential was monitored for 8 days in the rhizosphere of tomato (Lycopersicon esculentum L.) in response to contrasting Fe supply. The concentration of Cu in roots was enhanced under Fe deficiency in the acidic soils. Shoot Cu however did not vary with the Fe status of the plant. The plant Fe status had little effect on rhizosphere pH, redox potential or Cu concentration in solution in either acidic or calcareous soils. Marked differences in pH and solution Cu concentration were observed between rhizosphere and uncropped soils. Roots induced an increase in pH of acidic soils and a decrease in solution Cu concentration in all soils. The decrease in solution Cu concentration in acidic soils may be explained by the increase in rhizosphere pH. The proposed device provided new data on the fate of Cu in the rhizosphere and showed a positive correlation for the four soils considered together between the total Cu concentration in soil solution and root Cu concentration.     

Dependence of the concentration of the demi-maximal action of a channel blocker on the agonist concentration

Based on the analysis of kinetic scheme of blocking of open channels at any number of blocker binding sites, the dependence of current on blocker concentration was found. A variant of this dependence for a trapping blocker was also found. The restrictions of the applicability of the Hill equation and the necessity of taking into account the dependence of the concentration of demi-maximal blocker action (IC50) on the concentration of agonist were shown.     

Fluorometric determination of the DNA concentration in municipal drinking water

DNA concentrations in municipal drinking water samples were measured by fluorometry, using Hoechst 33258 fluorochrome. The concentration, extraction, and detection methods used were adapted from existing techniques. The method is reproducible, fast, accurate, and simple. The amounts of DNA per cell for five different bacterial isolates obtained from drinking water samples were determined by measuring DNA concentration and total cell concentration (acridine orange epifluorescence direct cell counting) in stationary pure cultures. The relationship between DNA concentration and epifluorescence total direct cell concentration in 11 different drinking water samples was linear and positive; the amounts of DNA per cell in these samples did not differ significantly from the amounts in pure culture isolates. We found significant linear correlations between DNA concentration and colony-forming unit concentration, as well as between epifluorescence direct cell counts and colony-forming unit concentration. DNA concentration measurements of municipal drinking water samples appear to monitor changes in bacteriological quality at least as well as total heterotrophic plate counting and epifluorescence direct cell counting.