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Biomedical subjects

M Hentschel

Publications and source records attributed to M Hentschel.

At least 19 recordsLinked to original sources
PubMed1995

Endothelin (ET-1) is involved in the contrast media induced nephrotoxicity in children with congenital heart disease.

In 77 children with congenital heart disease urinary endothelin-1 (ET-1), an indicator of intrarenal endothelin release, was compared to urinary excretion of total protein, albumin, immunoglobuline G (IgG), alpha 1-microglobuline (alpha 1-MG), N-acetyl-beta-D-glucosaminidase (NAG) and villin. Urine samples were collected the day before and immediately after cardiac angiography with high (Conray 70; n = 56; CON) or low osmolality contrast media (Solutrast 300; n = 21; SOL) to assess the relationship between urinary endothelin and glomerular and tubular nephrotoxicity of contrast media. The children were further subdivided according to age: less than 1 year-CON 1 (n = 20); SOL 1 (n = 12) and 1-18 years CON 2 (n = 36); SOL 2 (n = 9). Results (median): 1. There are no significant changes in total protein-, albumin- and IgG-excretion as parameters of glomerular toxicity. 2. Tubular toxicity of contrast media is shown by significant increase of alpha 1-MG-(10.0 to 23.2 mg/g Crea; p < 0.001), NAG-(5.9 to 9.6 mg/g Crea; p < 0.001) and Villin-excretion (1.0 to 2.0 STS, p < 0.001) in all children. 3. Endothelin excretion (101.0 to 163.0 ng/g Crea, p < 0.001) and concentration (42.5 to 56.0 pg/ml; p < 0.001) were elevated after angiography in all children. 4. The changes in endothelin excretion are correlated to the changes in alpha 1-MG (r = 0.65; p < 0.001) and NAG (r = 0.43, p < 0.001) in all children.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Endothelin excretion during ketoacidosis does not correlate with tubular dysfunction.

Urinary excretion of endothelin was measured by radioimmunoassay in children with diabetes mellitus during severe ketoacidosis and 12 days later when blood pH and blood glucose concentrations were normal. Metabolically stable diabetic children served as controls. Results from apparently healthy children without diabetes mellitus were used as normal values. Renal tubular injury was evaluated by the urinary excretion of the proximal tubular marker alpha 1-microglobulin and the distal tubular marker Tamm-Horsfall protein (THP). During ketoacidosis we detected a decreased glomerular filtration rate associated with highly significant changes in the excretion of alpha 1-microglobulin, indicating proximal tubular damage, and THP, suggesting disturbance of cells of the ascending loop of Henle. The daily excretion of endothelin was unaltered but the ratio of endothelin/creatinine or endothelin excretion/creatinine clearance were significantly enhanced. In conclusion, we could demonstrate that, despite a proximal and distal tubular cell dysfunction, endothelin excretion is not elevated during ketoacidosis. The increased endothelin excretion when related to creatinine clearance may be a consequence of disturbed proximal tubular function or dysfunction of the renal medulla.

Adolescent↗
PubMed1992

Pharmacokinetics of isometronidazole. Basic model and estimation of the kinetic parameters from experimental data.

For the optimal timing of application of radiosensitizers in a course of radiotherapy it is important to know the sensitizer concentration at the time of irradiation. We have studied the pharmacokinetics of the hypoxic cell sensitizer isometronidazole in man and mouse and analyzed the data on the basis of an open two-compartment model after extravasal application. The parameter estimation is performed directly to avoid estimation biasing and data points from blood and tissue compartments are approximated simultaneously. The values obtained differ significantly from the estimations calculated by other authors for the same data.

Animals↗
PubMed1991

[The radiation-sensitizing effect of isometronidazole following its intravesical application in bladder carcinoma. A clinical phase-II study].

The radiosensitizing efficacy of iso-metronidazole, a 4-nitroimidazole derivative, was evaluated in a prospective clinical phase-II study. The results of combined radiotherapy of 25 patients with bladder cancer were compared with those of a control group of 25 patients treated with radiotherapy only. Tumor regression six months after radiotherapy was used as an endpoint. The surgical procedure was performed as double TUR. Evaluating the local tumor control after additional application of iso-metronidazole a gain factor of 1.2 is obtained.

Administration, Intravesical↗
PubMed1989

The phase diagram of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine/sucrose in the dry state. Sucrose substitution for water in lamellar mesophases.

The phase diagram of the binary system, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)/sucrose, was determined by DSC. In contrast to dry DPPC, which exhibits chain melting at 342.5 K, the main feature of the DPPC/sucrose system is eutectic melting at 320 K. This was supported earlier by Crowe, J.H., Crowe, L.M. and Chapman, D. (Science 223 (1984) 701-703), who reported a drastic decrease in the chain-melting temperature of the dry lipid in the presence of some mono- and disaccharides. Electron microscopy suggests that the phase structures on either side of the phase transition are of the lamellar type. Definite sugar saturation concentrations can be derived from this phase diagram. Up to about 17 mol% sucrose, i.e., 1 mol of sucrose per 5 mol of lipid is adopted by DPPC in the low-temperature phase Lc. In the high-temperature phase Lm the saturation concentration is well above 90 mol% sucrose at 320 K (eutectic point) but decreases with increasing temperature. The lower limit of 50 mol% sucrose is reached at 455 K. At this temperature, peritectic melting of sucrose occurs. Because of some similarities in the phase diagrams of DPPC/sucrose and DPPC/water, it is possible to understand the sucrose substitution for water in dry lamellar mesophases.

1,2-Dipalmitoylphosphatidylcholine↗