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Biomedical subjects

H Vogel

Publications and source records attributed to H Vogel.

At least 217 records · Page 12Linked to original sources
PubMed1989

Steady-state intravenous pharmacokinetics of pirenzepine in patients with hepatic insufficiency and combined renal- and hepatic insufficiency.

The steady-state intravenous pharmacokinetics of pirenzepine has been investigated in patients with chronic liver disease and others with combined chronic liver disease and renal insufficiency. The plasma clearance (CL) of Pirenzepine, steady-state plasma concentration Cmin(ss) and dominant half life t1/2 gamma were not significantly altered in the chronic liver disease group. In patients with renal and hepatic insufficiency, CL was reduced, t1/2 gamma was prolonged from 11.1 to 19.4 h and Cmin(ss) was elevated from 36 ng/ml to 66 ng/ml compared to healthy controls. Plasma concentrations remained in the therapeutic range and the dosage regimen was well tolerated. Adjustment of the dose of pirenzepine need be considered only in cases of severe impairment of both renal and hepatic elimination.

Adult↗
PubMed1989

Steady-state intravenous pharmacokinetics of pirenzepine in patients with differing degrees of renal dysfunction.

The steady-state intravenous pharmacokinetics of pirenzepine has been investigated in 57 subjects whose renal function ranged from normal to chronic failure requiring regular haemodialysis. Pirenzepine renal clearance, total clearance and terminal (dominant) half-life were found to be correlated with the creatinine clearance (CLCR), but this was not the case for the volume of distribution and the nonrenal clearance. The therapeutic regimen was well tolerated by all subjects. Haemodialysis did not significantly contribute to the elimination of pirenzepine. Dosage adjustment need only be considered in patients with CLCR less than 25 ml/min in order to reduce the frequency of minor side-effects.

Adolescent↗
PubMed1989

Characterization of the promastigote surface protease of Leishmania as a membrane-bound zinc endopeptidase.

The effects of a variety of inhibitors suggested that the promastigote surface protease (PSP) of Leishmania might be a zinc metalloprotease. To investigate this possibility, we conducted atomic emission and absorption spectroscopic analyses, which show that PSP contains 1 atom of zinc per 63-kDa monomer. Further studies showed that the enzyme can be biosynthetically labeled with 65ZnCl2. The comparison of the amino acid sequence of Leishmania major PSP with nine other zinc metalloproteinases revealed significant similarity in the area of their zinc-binding sites. These data show clearly that the promastigote surface protease of Leishmania is a zinc metalloproteinase. Secondary structure analysis by circular dichroism spectroscopy indicates that PSP contains over 40% beta-strand and less than 20% alpha-helical structure. The molecular masses of amphiphilic PSP (152 kDa) and of hydrophilic PSP (142 kDa), determined by quantitative electron scattering, suggest that the purified enzyme occurs in solution, and presumably at the cell surface, as a non-covalent homodimer.

Amino Acid Sequence↗
PubMed1989

Influence of proprioceptive information on space orientation on the ground and in orbital weightlessness.

Conscious space orientation depends on afferent information from different sense organs including the labyrinth, the eyes, tactile cues from the skin, joint receptors, muscle spindles, tendon organs and possibly viscera. An important role is played by impulses from the cervical position receptors in interaction with concomitant information from the otolith system. In order to isolate the effect of cervical position receptors from that of the otolith system, space experiments in orbital weightlessness and in parabolic aircraft flight were performed. It was found that stimulation of the neck receptors in weightlessness markedly influences the perception of the subjective vertical and horizontal and in addition has a weak effect on ocular torsion.

Adaptation, Physiological↗
PubMed1989

31P nuclear magnetic resonance study of the effect of azide on xylose fermentation by Candida tropicalis.

Maximal ethanol production by Candida tropicalis grown on xylose was obtained at an oxygen transfer rate of 5 to 7 mmol/liter per h. Addition of 0.2 mM azide increased the ethanol yield by a factor of 3 to 4, based on the cell mass produced, and decreased the formation of the by-product xylitol by 80%. In the presence of azide, ethanol was reassimilated before the carbon source was depleted. At all oxygenation levels studied, azide caused 25 to 60% of the carbon to be lost, most probably as carbon dioxide. Identical spectra were obtained with 31P nuclear magnetic resonance spectroscopy performed on extracts of C. tropicalis grown on xylose in the absence and presence of azide. Azide lowered the levels of sugar phosphates. Enzymatic analysis showed extremely low levels of fructose 1,6-diphosphate compared with the levels obtained in the absence of azide, while the level of malate, a citric acid cycle intermediate, was not influenced by azide. 31P nuclear magnetic resonance spectroscopy performed on xylose-grown whole cells of C. tropicalis showed that azide lowered the intracellular pH, inhibited the uptake of external Pi, and decreased the buildup of polyphosphate in relation to results with untreated cells. Similar results were obtained with the uncoupler of oxidative phosphorylation carbonyl cyanide m-chlorophenylhydrazone (CCCP), except that CCCP treatment led to extremely high levels of internal Pi. The dual effect of azide as a respiratory inhibitor and as an uncoupler is discussed with respect to the metabolism and product formation in xylose-assimilating C. tropicalis.

Azides↗
PubMed1989

[MR tomography of the elbow joint].

MR examinations of the elbow joint of three healthy subjects and a comparison with corresponding sections of anatomical preparations show that MR tomography enables not only an excellent differentiation of muscles, tendons and of the articular capsule, but will also visualise vessels and nerve tracts. MR tomography proved superior to the conventional methods in demonstration of separate fragments and inflammatory changes in the bone on examining 11 pathological elbow joints: congenital malformation, osteochondritis dissecans, ostitis, ulnar and radial nerve lesions, completely healed radius fracture and epicondylitis of the radial and ulnar humerus. Epicondylitis could not be demonstrated by MR. Magnetic resonance tomography seems to be the only method that enables direct visualisation of the nerve paths at the elbow joint.

Elbow Joint↗
PubMed1989

[Bladder calcinosis caused by schistosomiasis].

In schistosomiasis calcifications of the urinary bladder are characteristic signs that allow a corresponding diagnosis in endemic regions. Problems concerning differential diagnosis occur only in very rare cases. The calcifications of the bladder can be easily detected by native diagnostics. A late complication in an affected bladder is often a bladder carcinoma.

Calcinosis↗
PubMed1989

Difficulties of risk determination from the use of new contrast media.

The difficulties with comparing data on the risks involved in the use of conventional contrast media and new low-osmolar contrast media are presented. These difficulties are a result of the necessary size of the groups to be compared and the problems of obtaining data. Prospective studies, carried out by a single researcher, probably have the greatest reliability. In multicentered studies with a larger number of participants, a number of factors must be reckoned with. The assessment of the same reaction can vary considerably, depending on the initial illness and interest of the patient or physician. This will, of course, influence the collection of the data. Due to the fact that complications and side effects are more frequent than deaths, the reduction of the first two through the use of new contrast media is statistically easier to ascertain. It can be assumed from the studies performed thus far that the risk of mortality is also reduced. Definite statistical guarantees do not as yet exist, and it is possible that they will never be produced.

Contrast Media↗
PubMed1989

[Occupational disability among teachers and its relation to subjective health status and professional performance].

The aim of this study was to examine the relationship between absenteeism and functional health state, action competence, realization of professional goals and essential needs as well as subjective strain in job and family and type A behaviour pattern. The results of discriminant analyses from a sample of 774 teachers (group 1; no sickness leave days, group 2: sickness leave days greater than 28) are discussed.

Absenteeism↗
PubMed1988

Epidermal growth factor receptor in meningiomas is expressed predominantly on endothelial cells.

The immunohistochemistry of the epidermal growth factor receptor (EGFR) was studied with monoclonal antibodies in 12 meningiomas of various histologic subtypes, nine benign and three malignant. Strong immunoreactivity of EGFR epitopes was found in the endothelia of the tumor vasculature in six cases. A much weaker reaction was detected within tumor cells in six cases, in one of which it was diffuse and five focal. No correlation was established between the presence of EGFR epitopes and the histologic type or biologic behavior of the meningiomas. The results suggest that the EGFR may participate in tumor angiogenesis, but its role in the growth of neoplastic meningioma cells remains elusive.

Endothelium, Vascular↗
PubMed1988

Do folliculo-stellate adenomas of the pituitary gland exist or are they intrasellar meningiomas?

A tumor arising in the pituitary fossa and having some of the histological and ultrastructural features of a recently described tumor, purportedly originating from the folliculo-stellate cells of the anterior pituitary, is presented. The results of our ultrastructural and immunohistochemical studies, however, favored a meningeal origin and suggested that the neoplasm was most likely a secretory meningioma.

Adenoma↗
PubMed1988

Single doses of catecholamines in the rat: catecholaminotropic, but not hyperglycemic.

1. As in two "lower" vertebrates, the lamprey and the eel, single intravascular injections of physiological doses (2.5 micrograms/kg) of epinephrine (E) into the rat immediately increased levels of plasma dopamine (DA) and norepinephrine (NE). 2. Single doses of DA (5 micrograms/kg) enhanced circulating NE and E, while NE (5 micrograms/kg) had no clear impact on the plasma levels of the other two catecholamines (CAs). 3. These data are at variance with findings in the eel, where all three CAs are mutually stimulatory; and in the lamprey, where only E stimulates release of the other two CAs. 4. It appears that E-stimulated CA release is widespread or ubiquitous among vertebrates, and that complex interactions between circulating CAs must be considered under experimental, physiological, and clinical conditions. 5. None of the injections had a significant hyperglycemic effect.

Anguilla↗
PubMed1988

Structural fluctuations of a helical polypeptide traversing a lipid bilayer.

Time-resolved fluorescence anisotropy (FA) measurements are reported for five helical bilayer-spanning henicosapeptides, each containing one tryptophan at sequence position 1, 6, 11, 16, or 21. The FA decay reflects two molecular processes in all cases: local internal fluctuations of the tryptophan side chain with a relaxation time of 200-500 ps, and motions of the whole polypeptide molecule with a relaxation time of 9-10 ns. The amplitudes of the fast fluctuation are largest at the helix ends and decrease toward the center of the helix. A similar observation was made for the helical polypeptides dissolved in organic solvents showing that the mobility gradient along the polypeptide sequence is an inherent property of the polypeptide helix and not due to the lipid bilayer. However, the amplitudes of the fast fluctuations can be modulated by the physical state of the lipid bilayer. With decreasing temperature, the internal mobility of the tryptophan in all positions decreases with an abrupt change at the lipid-phase transition. Concomitant molecular dynamics calculations indicate a correlation between the fast FA decay and conformational fluctuations within the helix. According to the simulation, the conformation of the polypeptide is on average predominantly helical, but actually the molecule can fluctuate between a variety of different substructures. The conformational fluctuations are largest at the helix ends and provide the free space required for rotation of the indole ring around the tryptophan side chain bonds.

Amino Acid Sequence↗