The detection of a choleriform thermolabile enterotoxin in clinical strains of Proteus isolated in different infections

The capacity of Proteus strains, isolated from patients with purulent inflammatory, urological and enteric infections, for the production of choleriform thermolabile enterotoxin was studied by means of the enzyme immunoassay (EIA) with the use of antitoxic serum to Escherichia coli enterotoxin. Out of 125 strains, 27 (21.6%) showed the capacity for producing choleriform thermolabile enterotoxin in EIA experiments. The results thus obtained indicate that EIA techniques can be used, in principle, for detecting the capacity of Proteus for the production of choleriform thermolabile enterotoxin.     

Age-related characteristics of the effects of epithalamin on serotonin metabolism in the pineal gland of rats]

The biosynthesis of serotonin into melatonin was decreased in old (18-20-month) in comparison to young (4-5-month) male Wistar rats. 5-day morning injections to young and old rats with polypeptide pineal preparation (epithalamin) in a dose of 2.5 mg/kg of body weight induced the increase in the night peak of serotonin, N-acetylserotonin and melatonin in young and melatonin alone in old rats and did not influence 5-methoxytryptamine, 5-oxy- and 5-methoxyindoleacetic acids level. These data support suggestion of ultrashort loop between pineal peptides and indoles and that epithalamin increases the metabolism of serotonin into melatonin.     

Effects of excess and deficiency of thyroid hormones in the body upon blood melatonin in pubertal male rats

Experiments have been carried out on Wistar line pubertal male rats in Winter. Radioimmunological method showed, that in intact animals the night peak of melatonin in blood was 994,36 +/- 195,99 pM/l, following ten-days intramuscular thyroxin injection (100 mg/100 g body mass)--2560,52 +/- 322,04 pM/1 and 20 days after, following bilateral thyroidectomy--117,13 +/- 16,35 pM/l, that totals 257,5% and 11,8%, respectively. Thus, the night peak of melatonin depends upon thyroid hormones concentration in blood.     

Effect of acidosis on the membrane potential of intact guinea pig aortic endothelial cells

The effects of a decrease in the extracellular pH from 7.4 to 6.9 on the membrane potential (MP) of intact non-stimulated guinea pig aortic endothelial cells and their ATP-induced electrical responses were studied using a whole-cell mode of the patch-clamp technique. Superfusion of the strip with CO₂-−HCO ₃ ⁻ -buffered acidic solution evoked endothelial depolarization of 6.1±1.0 mV. In Ca²⁺-free medium, after the MP had been stabilized at a depolarized value, there was no shift in the MP due to extracellular acidification to pH 6.9. In the case of using tris-buffered solution, the same drop in the extracellular pH in Ca²⁺-containing medium induced no change in the endothelial MP. Subsequent superfusion with CO₂−HCO ₃ ⁻ -buffered solution with pH 6.9 evoked endothelial depolarization of 7.3±1.5 mV. Changing from tris-buffered to CO₂−HCO ₃ ⁻ -buffered solution at a constant buffer pH 7.4 also induced endothelial depolarization, suggesting that intracellular pH is a possible factor that modulates leak Ca entry. The duration of ATP-induced endothelial hyperpolarization at pH 6.9 significantly dropped (76±5 sec, on average) compared with that at pH 7.4 (121±14 sec). It is concluded that modulatory effect of acidosis on the MP of endothelial cells and their ATP-induced electrical responses are caused by inhibition of leak and ATP-stimulated calcium entry into these cells.     

Caffeine-induced electrical responses of intact endothelial cells

The mechanism of caffeine-induced endothelial-dependent relaxation of vascular smooth muscle cells has been studied by recording caffeine application-induced electrical responses from intact guinea pig aortic endothelial cells. Depending on the values of the membrane potential, caffeine evoked either hyperpolarizing responses (V _m<−45 mV, 88.9% of the cells tested), or depolarizing reactions (V _m>−45 mV). The mean amplitude of caffeine-induced hyperpolarization of endothelial cells was 11.2±5.5 mV, which is comparable with the amplitude of ATP-induced hyperpolarization. The amplitude of caffeine-induced depolarization was 8.9±3.4 mV, on average. It was shown that caffeine-induced hyperpolarization of endothelial cells is a result of calcium release from the intracellular stores with subsequent activation of calcium-dependent potassium channels. Intracellular calcium stores involved in caffeine-induced responses are different from those involved in ATP responses. It is concluded that calcium mobilization from the intracellular stores of endothelial cells and, possibly, activation of calcium entry contributes to the caffeine-induced endothelial-dependent relaxation of vascular smooth muscle cells.     

Estimating growth and mortality in stage-structured populations

This paper presents a practical numerical method for separatingand estimating growth and mortality coefficients in stage- orsize-structured populations using only observations of the relativeor absolute abundance of each stage. The method involves writinga system of linear ordinary differential equations (ODEs) modellingthe rate of change of abundance. The solution of the differentialsystem can be numerically approximated using standard (e.g.sixth-order Runge-Kutta-Felhberg) methods. An optimization problemwhose solutions yield ‘optimal’ coefficients fora given model is formulated. The ODE numerical integration techniquecan then be employed to furnish required function and gradientinformation to the optimization algorithm. The data-fittingsoftware package ODRPACK is then successfully employed to estimateoptimal coefficients for the ODE population model. Simulationexperiments with four- and eight-stage model populations illustratethat the method results in the successful estimation of coefficientsof mortality and growth from abundance data.     

Spectrum of pneumotropic pathogens in pediatric patients with acute bronchitis and pneumonia]

One hundred eighty nine children with acute bronchopulmonary infectious pathological processes were examined bacteriologically and serologically for typical pneumotropic pathogens, 47 of them being as well examined for atypical organisms. Microbial associations mainly with Mycoplasma and Pneumocystis and to a lesser extent with Chlamydia were isolated from the majority of the children. Reactivation of the cytomegalovirus infection was observed in 25 per cent of the children. Pneumonia and bronchitis due to Mycoplasma pneumoniae either as a monoagent or in associations were mainly stated in children over 7 years of age. No significant changes between the indices of the infection due to a definite organism and the active progression of the infectious process of the same etiology were revealed, though in the cases of chlamydiosis the changes reached almost 10 per cent. In cases of acute bronchitis and pneumonia the chlamydial or cytomegalovirus infection could be assumed to be of the persisting nature, mainly acute in cases of pneumococcal infection, mixed in cases of hemophilic or pneumocystic infection, primary contamination with a tendency to prolonged in cases of mycoplasmic infection. The findings of the examination and the clinical and anamnestic data showed that the clinical picture of acute pneumonia had specific features associated with the supposed etiological agents, still it could change under the action of associations of pneumotropic pathogens.     

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