Search PubMed⌕ Search

Biomedical subjects

W Schulz

Publications and source records attributed to W Schulz.

At least 109 records · Page 6Linked to original sources
PubMed1982

RNA polymerase: correlation between transcript length, abortive product synthesis, and formation of a stable ternary complex.

In order to investigate the relationship between the stability of the ternary complex RNA polymerase-T7 D111 DNA-RNA product and the length of the bound RNA product, we have developed a protocol for the production of stable ternary complexes of known length and composition. The assembly of the ternary complex is achieved by utilizing a dinucleotide tetraphosphate (pppApU) as a selective primer, which is augmented by one or more appropriate nucleotides. The labeled products were characterized by autoradiography of gel electrophoresis patterns, which were then quantified. The criterion for stability is the protection from perturbations (a salt-jump or a rifampicin challenge), which effectively inhibit initiation. The formation of a bound ribotetranucleotide ternary complex confers stability and terminates abortive product synthesis.

Chromatography, Thin Layer↗
PubMed1982

[Osteopenia. A problem of long-term dialysis].

Hemodialysis induced osteopenia represents one of the serious late complications of long-term treatment with hemodialysis. The incidence of osteopenia in our hemodialysis-patients ranges between 5 and 10 percent (Atkinson et al. 1973; Delling et al. 1976; Heidler et al. 1976; Parfitt 1976; Fuchs et al. 1977a; Henning et al. 1977; Schulz 1978, 1979; Madsen 1979; Schulz et al. 1980, 1981). Well timed variation of the conventional electrolytecomposition of dialysate can prevent osteopenia in many cases successfully. Precise histological classification of bone (histomorphometrical evaluation of bone-biopsy) and determination of parathormon- and fluor-level are the obligatoric precondition of adequate osteopenia-treatment. Therapy of osteopenia comprises--beside decrease of dialysate calcium and -magnesium--stepwise increase of NaF--and 1,25(OH)2D3-application. Surveillance during therapy should include monitoring of calcium, phosphate and fluor-metabolism, microradioscopy of hand skeleton, rebiopsy of bone (iliac crest) and determination of iPTH.

Adolescent↗
PubMed1982

[Extent of beta-blocking action of S- and R-penbutolol during exercise testing (author's transl)].

The effect of 40 mg penbutolol (pure S-form = laevo penbutolol) and 40 mg isopenbutolol (pure R-form) on heart rate and blood pressure during exercise testing was investigated under double-blind, randomized, placebo-controlled conditions in 9 probands. 1.5 and 5.5 hours after ingestion of 40 mg penbutolol, resting, standing, exercise, and recovery heart rate as well as systolic pressure during exercise displayed a significant decline. Diastolic blood pressure rose slightly 1.5 hours after penbutolol. Isopenbutolol had no significant effect on resting and standing heart rate. 1.5 hours after ingestion, a slight reduction in exercise and recovery heart rate could be confirmed. The decline, however, was significantly lower than that achieved with penbutolol. In comparison with its dextrorotatory isomer, isopenbutolol, penbutolol has an approximately 100-fold more potent effect on exercise heart rate. This is also reflected in the drug's duration of action.

Adult↗
PubMed1982

Subtypes of acute postinfectious glomerulonephritis. Synopsis of clinical and pathological features.

42 kidney biopsies from adults and children suffering from acute postinfectious glomerulonephritis were examined by light microscopy, immunofluorescence and electron microscopy. The biopsies were obtained within 9 weeks of the onset of the first clinical symptoms. The results show not only a range of variation in the histological picture (particularly in the accumulation of leukocytes in the capillary lumens, and in the degree of cell proliferation) but also different immunofluorescent patterns which we have called the "starry sky", "garland" and "mesangial" patterns. These patterns correspond to characteristic differences in the electron microscopic picture. The "starry sky" pattern (IgG, IgM and/or IgA, combined with C3) occurs mainly in the first weeks of the disease and is associated with an endocapillary-mesangial glomerulonephritis. This may turn into a "mesangial" pattern (mostly C3 alone) which is associated mainly with mesangial proliferation. Four types of immune deposits can be observed electron microscopically in all three patterns (subendothelial, subepithelial, mesangial and intramembranous), but their different quantitative distribution determines the characteristic picture. Subepithelial deposits (so called "humps") often considered characteristic of poststreptococcal glomerulonephritis play a dominant role in the "garland" pattern. The cases with a "garland" pattern often show strikingly high levels of proteinuria (greater than 5 g/24 hr). It is believed that in patients with postinfectious glomerulonephritis deposition of immune complexes of various composition is responsible for producing the described subtypes depending on their different distribution in the glomeruli. It seems possible that these subtypes have different clinical significance, something which could be confirmed by performing follow-up studies.

Acute Disease↗
PubMed1981

Rifampicin inhibition of RNA synthesis by destabilisation of DNA-RNA polymerase-oligonucleotide-complexes.

Although the antibiotic rifampicin inhibits the transcription of poly[d(A-T)] by E.coli RNA polymerase, a series of short oligonucleotides is produced. It is claimed that the overall inhibition of RNA synthesis by rifampicin is caused by a destabilising effect on the binding of the intermediate oligonucleotides to the active enzyme-DNA complex. Rifampicin itself can only interact specifically with RNA polymerase if the enzyme is free or in a binary complex with DNA. However, the enzyme is not susceptible in a ternary complex, even if the "RNA" is as short as a trinucleotide.

DNA↗
PubMed1981

[Consequence of habitual use of laxatives (author's transl)].

Though habitual, but not excessive use of laxatives can be observed frequently, no accompanying clinical symptoms have yet been described. The frequent observation of tetany and edema is striking, there is a marked decrease of potassium clearance and an incipient impairment of creatinine clearance. A secondary hyperaldosteronism can be ruled out. The electrocardiograms of 9 patients show signs of mild hypokalemia, which in 2 patients were first misinterpreted as myocardial ischemia and in one patient taken as indication of myocarditis. Oral administration of potassium normalizes the electrocardiograms.

Adolescent↗
PubMed1981

The distribution of metastases in the liver. A quantitative postmortem study.

Seventy-five livers with metastases were cut sagitally into 1 cm thick slices. A total number of 11,581 metastases sections was exactly mapped. There was an average of 154 metastases sections per liver. The average diameter of the metastases was 1 cm. 40% of the metastases reached to the hepatic surface, and 60% were invisible due to their deposition in the internal parenchyma. In 8% of the livers there were only superficial metastases (average 3.2 metastases), and in 12% were only deep metastases detected (average 2.6). The total number of superficial metastases increased with increasing diameter of the secondary tumors. An approximately homogeneous distribution of hepatic metastases within the liver parenchyma has been demonstrated.

Anthropometry↗
PubMed1981

Direct determination of hepatic extraction of verapamil in cardiac patients.

Hepatic extraction of verapamil was determined directly in cardiac patients undergoing diagnostic catheterization and receiving 10 mg verapamil intravenously or intra-arterially. The extraction curves of verapamil concentrations in blood from the ascending aorta and hepatic vein were similar to those reported after single intravenous doses of indocyanine green. The rectilinear fall in concentration lasted 10 to 15 min. Mean hepatic extraction of verapamil in four patients who received intravenous doses was 0.86 (range 0.84 to 0.89) and in four who received intra-arterial doses was 0.87 (range 0.83 to 0.89). These estimates are the same as those for hepatic first-pass extraction determined by indirect methods based on areas under plasma concentration-time curves and requiring calculation of apparent hepatic blood flow. The results were considered to be proof that the first-pass effect of verapamil after oral doses is attributable mainly, if not entirely, to hepatic elimination.

Adult↗
PubMed1981

Microvascular injury distal to unilateral pulmonary artery occlusion.

We explored three questions: 1) does edema fluid accumulate distal to temporary unilateral pulmonary artery occlusion (TUPAO); 2) if so how rapidly does it accumulate; and 3) how is it affected by positive end-expiratory pressure (PEEP)? Using a tracheal divider we measured pulmonary capillary blood flow (Qc), tissue volume (Vt), and diffusing capacity (DLCO) in each lung with a rebreathing method. After control measurements in 12 dogs, the left pulmonary artery was occluded and measurements were repeated at intervals during 4 h of occlusion and 30 min after release of the occlusion. Six of the dogs were ventilated with 10 cmH2O PEEP. Finally the lungs were removed, weighed, and fixed for histology. TUPAO caused a 29% increase in Vt of the left lung without PEEP and a 59% increase with PEEP. After release of the occlusion, Qc and DLCO in the left lung returned to control levels within 30 min in dogs not on PEEP but remained depressed in dogs ventilated with PEEP even though PEEP was removed. At postmortem the left lung weighed more than expected in both groups of dogs but was significantly heavier in those on PEEP. Histology confirmed bronchovascular cuffing with edema and hemorrhage.

Animals↗
PubMed1981

Antianginal effect of nifedipine after intracoronary and intravenous administration judged by reduction of ischemic ST-segment depression in exercise tests.

The purpose of the study was to distinguish between the peripheral and the cardiac mode of action of nifedipine, a drug which inhibits transmembrane calcium transport. To assess the cardiac and peripheral antianginal effect independently, two routes of application were employed: systemic intravenous and intracoronary infusion into the left coronary artery of approximately equipotent doses.

Angina Pectoris↗