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Biomedical subjects

A Magyar

Publications and source records attributed to A Magyar.

43 records · Page 3Linked to original sources
PubMed1977

Renal response to vasopressin after inhibition of prostaglandin synthesis.

The renal effects of vasopressin (VP) in water-loaded and hydropenic conscious dogs were examined with and without the previous administration of prostaglandin (PG) synthesis inhibitors (indomethacin and meclophenamate). The parameters studied were: urinary output, sodium and potassium excretion, plasma and urinary osmotic concentration, total renal blood flow, mean arterial pressure, heart rate, and the clearance and extraction ratio of p-aminohippuric acid and inulin. The infusion of VP caused antidiuresis and marked saluresis during water diuresis, whereas it was found to be diuretic and saluretic in hydropenic animals. Inhibition of PG synthesis greatly enhanced the antidiuretic activity of VP and abolished its saluretic and diuretic actions. Changes in renal water and solute excretion and changes in the hemodynamic parameters are uncorrelated. It is concluded that intrarenal PGs may play an important role in modulating the renal action of VP.

Animals↗
PubMedDate not supplied

Demonstration of stereoselective disposition of warfarin enantiomers by whole-body autoradiography.

The oral anticoagulant warfarin and its 14C-labelled derivative are commercially available in racemic forms. Two methods for the chromatographic resolution of the radiolabel were used to investigate the distribution of radioactivity of radioactivity of individual enantiomers in the rat by whole-body autoradiography. Computer-assisted quantification of autoradiograms indicated the average disappearance of levo-warfarin and its metabolites to be substantially slower than that of dextro-warfarin and its metabolites from the following organs: liver, pancreas, kidney, lung, blood, intestines.

Animals↗
PubMedDate not supplied

[Calcaneus osteotomy in flexible flatfoot in children (long-term results)].

The static of serve flexible flatfeet in children can be positively influenced by the varisation osteotomy of the Calcaneous by Kramer. The method is technically easy and imposes very few complications. This follow-up after a meantime of 12.4 years looks at 30 osteotomies. Subjective results were excellent. Objectively, the results must be regarded as good. Nontheless, the problem remains who should be operated, especially if we keep in mind that the nontreated flatfeet usually develop positively. So this method should remain in the hands of the experienced orthopedic surgeon.

Adolescent↗
PubMedDate not supplied

Novel, delta-opioid receptor-selective peptide antagonists: demonstration of a possible opioid interaction in the absence of a protonated nitrogen and attempts to locate the protonated nitrogen site.

We have recently (Rónai et al., 1992) introduced a family of novel delta-opioid receptor-selective peptide antagonists, based on the Tyr-Pro-Gly-Phe-Leu-Thr structure, where the nitrogen accepts substituents that make protonation possible (e.g. diallyl) as well as substituents (e.g. t-Boc) where protonation cannot occur. In this paper, we present the details of a design strategy where the structurally closely related biologically active and inactive compounds are suggestive of conformational requirements of action. Furthermore, since even those derivatives of the antagonist peptides where the N-terminus was free were either devoid of opioid agonist activity or were extremely weak agonists, it is suggested that these antagonists do not interact with the conventional "opioid nitrogen site". To find this "conventional" site, a number of N-substituted (phenylglycyl-, alpha-Boc-lysyl-, alpha-Phe-beta-alanyl-) derivatives of Tyr-Pro-Gly-Phe-Leu-Thr hexapeptide were synthesized and their biological activities were determined in the mouse vas deferens bioassay.

Amino Acid Sequence↗
PubMedDate not supplied

The outcome of pancreatic fistulas developed after surgery for pancreatic pseudocysts.

Pancreatic fistulas (PF) develop in about 20% of cases operated for pancreatic pseudocysts. The authors analyse 81 cases of postoperative PF. These were formed following 991 operations performed for pancreatic pseudocysts (PPCs) in 850 patients from 1987 to 1992. It is concluded that the incidence of PF formation is significantly (P < 0.01) increased following interventions for acute-type pseudocysts and after external drainage. One-third of the fistulas closed spontaneously within 1-4 weeks, while another 1/3 persisted for 1-6 months before gradual closure. Closure of fistulas was facilitated by inhibition of pancreatic secretion with Somatostatin or endoscopic intervention (EST, endoprosthesis) in 24% of all cases. Only 15% (14 cases), of the fistulas, i.e. 1% of total patients, required surgery. The procedure of choice in the 14 cases was exstirpation of fistulas alone (2 cases) or combined with necrectomy (10 cases), or with distal pancreatic resection (2 cases). In cases of drained pancreatic fistulas observation can be an appropriate treatment option, while long-standing fistulas producing large amounts require intervention.

Adult↗
PubMedDate not supplied

Opioid antagonist properties of the highly delta-receptor-selective BOC-Tyr-Pro-Gly-Phe-Leu-Thr (OtBu) peptide and of its Phe1 and Mel1 analogues.

BOC-Tyr-Pro-Gly-Phe-Leu-Thr(OtBu) is a potent, highly delta-opioid receptor-selective competitive antagonist, the Ke values in the mouse vas deferens in vitro assay against [D-Ala2, D-Leu5]-enkephalin [D-Pen2, D-Pen5]enkephalin and deltorphin-II being 39.5, 38.7 and 27.3 nM, respectively, whereas those against [D-Ala2, MePhe4-Gly5-ol]enkephalin (DAMGO) and ethylketocyclazocine in the guinea-pig ileum are 368,000 and > 200,000 nM, giving a higher than 9000-fold delta- vs mu- and a higher than 5000-fold delta- vs kappa-selectivity ratio. The Ki values against various labeled delta-ligands in the rat brain receptor binding assay were in the 300-1000 nM range, whereas the Ki against [3H]-DAMGO was higher than 30,000 nM. The striking discrepancies between bioassay and receptor binding data show another aspect of already recognized differences of mouse vas deferens and rat brain delta-receptors. With the aim of producing a delta-selective affinity ligand, we synthesized the BOC-Mel1 derivative; however, there was a 175-fold loss of delta-receptor affinity in the bioassay and no indication of an irreversible interaction, but a delta-agonist effect appeared in spite of nonprotonated nitrogen. The corresponding BOC-Phe1 derivative had a 10 times higher affinity and, apparently, no agonist activity.

Analgesics↗