Further studies on the effect of aldosterone on electrical resistance of toad bladder

The fall in transepithelial electrical resistance which accompanies aldosterone stimulation of short-circuit current (Isc) in toad urinary bladder has been studied further to evaluate the possible causal role of this response in hormonal stimulation of Na+ transport. A steady-state change in tissue conductance was found to depend upon both the simultaneous stimulation of transport by the steroid and the metabolic state of the tissue. Changes in metabolic state alone did not alter resistance. A sustained increase in Na+ transport, dependent on pretreatment with aldosterone and elicited by addition of glucose, could be obtained without a sustained decrease in resistance. Amiloride, an inhibitor of Na+ uptake, produced changes in Isc that were linearly correlated with its effects on tissue conductance. On the basis of the conductance-Isc relationship with amiloride, the Isc response to aldosterone was about two-fold higher than would be predicted from its effects on conductance alone. Despite the apparent lack of a simple quantitative dependence of the change in Isc on the change in conductance when the response is fully developed, the results suggest that conductance changes may mediate the initial or early stage of the response.     

Sulfation of parabens and tyrosylpeptides by bacterial arylsulfate sulfotransferases

Arylsulfate sulfotransferase purified from Eubacterium A-44 has higher specific activity than the enzymes from Klebsiella K-36 and Haemophilus K-12. Propylparaben and butylparaben were good substrates among several parabens. The antibacterial activity of parabens was reduced by the sulfation of the phenolic hydroxy group. Tyrosine-containing peptides, kyotorphin, enkephalin and cholecystokinin non-sulfate, were effective as acceptor substrates by A-44, K-36 and K-12 sulfotransferases.     

Characteristics of Listeria monocytogenes strains isolated in Russia and their typing using pulse electrophoresis

On the basis of specially developed scheme for the isolation of Listeria strains comprising 2 enrichment stages and the use of growth inhibitors, 128 L. monocytogenes cultures were isolated from clinical material, foodstuffs and sewage water. Highly virulent L.monocytogenes strains isolated from clinical material belonged to serovar 4b (54%) and 1/2a (38%), while those isolated from foodstuffs and sewage water belonged to 4b (74%). The restriction analysis of the chromosomal DNA of the isolated cultures with the use of restrictase EcoR1 on the basis of pulsed-field gel electrophoresis (PFGE) made it possible to distinguish Listeria strains in accordance with 5 types of restrictograms. The restrictograms of highly virulent L. monocytogenes strains, serovar 4b, belonged to types 1 and 2, while those of L. monocytogenes strains, serovar 1/2a, belonged to types 2 and 3. The comparative use of different methods for typing L. monocytogenes (sero-, phago-, bio- and resistotyping, the analysis of plasmid composition and restriction analysis) revealed that the combination of serotyping and restriction analysis on the basis of PFGE proved to be most promising for the characterization of the isolated L. monocytogenes strains and the assessment of their epidemic importance.     

The renin-angiotensin system in left ventricular remodeling

Left ventricular remodeling is a dynamic process that occurs in reaction to an insult to the myocardium. The response to either loss of cells, as may occur following myocardial infarction, or to hemodynamic overload, as may occur in aortic stenosis, is an attempt to maintain cardiac output and normalize wall tension. This is accomplished through the activation of the renin-angiotensin system and hypertrophy of noninfarcted segments of the myocardium. in the case of moderate or large infarctions these mechanisms fail to normalize wall stress. The stimulus to further remodeling remains, viable myocytes hypertrophy (with greater increases in cell length than width), the mass-to-volume ratio increases, and an exponential increase in wall stress results. This increase in myocyte tension has been associated with premature myocyte cell death. Thus, a vicious cycle is established wherein overstretch of the myocardium while sustaining cardiac output leads to progressive myocyte loss and left ventricular dilation. The renin-angiotensin system plays an integral role in this process. Its inhibition by angiotensin-converting enzyme (ACE) inhibitors both chronically and immediately after myocardial infarction has been shown to decrease left ventricular volumes and reduce mortality. Controversy exists regarding the mechanism through which ACE inhibitors exert their effects. ACE inhibitors reduce afterload/preload, circulating angiotensin II levels, and raise circulating levels of bradykinin. It is not yet clear which mechanism is responsible for the greatest impact on left ventricular dilation and mortality. inhibition of the renin-angiotensin system is clearly beneficial to cardiac performance as well as morbidity and mortality when myocardium is lost and heart failure ensues. Specific modes of action require further definition, including local and systemic effects. Possible benefits of angiotensin receptor blockade versus augmentation of bradykinin requires definition, setting the stage for further study, while the beneficial therapeutic use of these agents continues.     

Complete clinical remission and subsequent relapse of bronchiectasis-related (AA) amyloid induced nephrotic syndrome

Systemic amyloidosis normally has a dismal prognosis. However, there are several case reports of protracted survival, usually as a response to measures designed to retard the further deposition of amyloid fibrils. In AA amyloid, most commonly associated with inflammatory rheumatological, bowel, and chest diseases, such interventions have had some success, but the dramatic response of complete resolution of nephrotic syndrome as a result of the regular institution of postural chest drainage and antibiotic therapy, in the clinical context of bronchiectasis, has been previously reported only once. In both of our cases, after protracted remission, such therapy was abandoned by the patients, leading both to recurrence of nephrotic syndrome and also eventually to end-stage renal failure requiring dialysis.     

Intestinal leakage of technetium-99m-MDP in primary intestinal lymphangiectasia

We present a case in which a patient with primary intestinal lymphangiectasia demonstrated abnormal intestinal accumulation of tracer during 99mTc-methylene diphosphonate (MDP) skeletal scintigraphy. Early intestinal leakage with gradual colonic migration and concentration was confirmed by repeat bone scan with serial acquisitions. The mechanism for the intestinal localization of 99mTc-MDP seen in this patient is not clear. Thus, intestinal lymphangiectasia can be a cause for extra-osseous localization of bone scan agents in the intestine.     

Selective monitoring of peptidase activities with synthetic polypeptide substrates and polyion-sensitive membrane electrode detection

A novel method to monitor specific peptidase activities in biological samples as complex as undiluted plasma/blood is described. The approach is based on the design of synthetic polypeptide substrates in which di- or triarginine sequences are linked to each other via one or more other amino acids recognized specifically by the peptidase to be determined. Detection of chymotrypsin and renin activities using synthetic substrates P4 (F-R-R-R-F-V-R-R-F-NH2) and P5 (R-R-R-L-L-R-R-L-L-R-R-R), respectively, serves to demonstrate the principles of this new assay system. A polyion-sensitive membrane electrode, prepared by doping polymer films with dinonylnaphthalene-sulfonate (DNNS), is shown to exhibit significant nonequilibrium electromotive force (EMF) responses toward these and other polycationic substrates at microgram/milliliter levels under physiological conditions. The same electrode, however, exhibits much smaller total EMF response toward the shorter fragments of the synthetic peptides generated by peptidase activity; hence, the addition of peptidase to a solution containing the synthetic substrate yields a change in electrode EMF response, the rate of which is proportional to the activity of peptidase present. Other synthetic polycationic peptides as well as natural polycationic peptides (e.g., protamine) that lack specific cleavage sites for chymotrypsin and renin, yet are detected by the DNNS-based membrane electrode, do not elicit any significant change in EMF response in the presence of the peptidases, confirming the feasibility and utility of the proposed bioanalytical method.     

Evaluation of the biliary tree: a comparison of percutaneous transhepatic cholangiography and ultrasonography

After we examined 45 patients with jaundice, using both percutaneous transhepatic cholangiography and ultrasonography, our results suggest that ultrasound is useful as an early screening procedure in evaluating patients with jaundice.     

Free-radical oxidation, the glutathione system and the status of the gastric mucosa in peptic ulcer in adolescents and young people under dynamic restorative treatment

1.5-2 versus 3-4 months following the in-patient stage of treatment without further antiradical therapy, patients-juveniles and young people with ulcer disease demonstrate compensated versus decompensated disorders in the glutathione system activity respectively, which results in disturbances in the free-radical oxidation processes, amplification of alteration, decrease in proliferation in the mucous membrane of the stomach. Antiradical therapy being continued avoids such a pathology. A necessity is substantiated for taking measures on an uninterrupted long-term basis, aimed to correct the free-radical oxidation processes in patients with peptic ulcer of juvenile age and young people.