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Biomedical subjects

M Hein

Publications and source records attributed to M Hein.

30 records · Page 2Linked to original sources
PubMed1992

Implications of a non-lamellar lipid phase for the tight junction stability. Part II: Reversible modulation of transepithelial resistance in high and low resistance MDCK-cells by basic amino acids, Ca2+, protamine and protons.

The transepithelial resistance of confluent epithelial cell monolayers was monitored to investigate the influence of basic amino acids, Ca2+, protamine and protons on tight junction electrical resistance. In an accompanying paper we investigated the effect of these substances on the lamellar/hexagonal II phase transition in reconstituted phospholipid membranes containing phosphatidylserine and phosphatidylethanolamine. We conclude that the permeability of tight junctions may be described by a lipid phase equilibrium where the lamellar phase corresponds to an open state and the hexagonal lipid phase to the closed state of the cell contact. This dynamic lipid model is well suited to describe the morphological as well as functional properties of the tight junctions.

Amino Acids↗
PubMed1984

Abscisic Acid metabolism by source and sink tissues of sugar beet.

The fate of exogenously applied, labeled abscisic acid (+/-)-(ABA) was followed in source leaves and taproot sink tissues of sugar beet (Beta vulgaris cv AH-11). The objective was to determine if differential pathways for ABA metabolism exist in source and sink tissues. Tissue discs were incubated for up to 13 hours in a medium containing 1 micromolar labeled ABA. At various time intervals, samples were taken for metabolite determination by reverse-phase high performance liquid chromatography. The labeled metabolites were identified by retention times using an online scintillation counter.Dihydrophaseic acid (DPA) aldopyranoside, DPA, phaseic acid (PA), ABA glucose ester (ABA-GE), and two unidentified compounds were recovered from both tissues. An additional unidentified metabolite was also present in root tissue. Leaf tissue discs exhibited a higher capacity for ABA conjugation, and root discs showed a greater preference for ABA catabolism to PA and DPA. After 4 to 5 hours, ABA incorporation into the various metabolites was proportional to the external ABA concentration in both tissues. But the internal ABA pool size was independent of external concentrations below 10(-6) molar. These results suggested that rates of ABA metabolism was proportional to the rates of uptake in both tissues.

Journal Article↗
PubMed1979

[Inability to work in gastrointestinal diseases].

11.7% of all cases with inability to work, 11.3% of all days with inability to work, and 13.6% of all dismissals from hospital of working people concern diseases of the digestive system. Gastroenterological diseases occupy an anterior place in inability to work. The inability to work is essentially determined by 7 diagnoses--gastritis and duodenitis, cholelithiasis, gastroenteritis and colitis, cholecystitis and cholangitis, ulcus ventriculi and duodeni, acute appendicitis. They comprise 78% of the days of inability to work. The endoscopic diagnostics is further to be developed with the further improvement of the organisation of treatment, particularly the cooperation between outpatient department and hospital and the interdisciplinary work.

Disability Evaluation↗
PubMedDate not supplied

[Comparison of roentgenological, macroscopic and histological degree of degeneration in varus gonarthrosis].

In 20 cases of varus gonarthrosis the degree of severity of osteoarthrosis was assessed preoperatively, intraoperatively and postoperatively for the medial and lateral compartments, respectively. The preoperative assessment was carried out on the basis of x-ray taken in an anterior-posterior and lateral view, whereas the intraoperative assessment was based on the recognizable macroscopic alteration of the femur and tibia. Following implantation of a total knee prosthesis, the resected osteocartilogical samples were assessed from a histological point of view. In the case of varus gonarthrosis there is a distinct difference in the degree of degeneration in the medial and lateral compartments. This difference becomes less noticeable if the assessment is carried out intraoperatively. The histological analysis shows that there are certainly differences between the compartments from a quantitative point of view but a late stage of osteoarthrosis was discernible both medially and laterally. From a histological point of view the radiological concept of the so-called "unicompartmental varus gonarthrosis" cannot be supported. In both compartments the osteoarthrotic process is more uniform than is to be expected.

Aged↗
PubMedDate not supplied

Vascular smooth muscle cell phenotype influences glycosaminoglycan composition and growth effects of extracellular matrix.

Rat neonatal and neointimal vascular smooth muscle cells differ dramatically from adult medical vascular smooth muscle cells in their growth properties, with the neonatal and neointimal cells exhibiting growth in the absence of exogenously added growth factors. Since it has been hypothesized that extra-cellular matrix proteoglycans may influence the growth and differentiation of vascular smooth muscle cells, we examined the ability of matrix derived from these cells to influence vascular smooth muscle cell proliferation. To produce test matrices, cells were grown to confluence and removed by brief alkali treatment. Test cells were seeded onto these matrices and the rates of growth in a growth-factor-deficient medium determined. Compared to plastic wells, matrix from neonatal or neointimal cells stimulated the growth of vascular smooth muscle cells. Interestingly, matrix from adult cells was less efficient at promoting growth. Enzymatic digestion of extracellular matrix heparan sulfate, but not of other glycosaminoglycans, further increased the growth-stimulatory effect of extracellular matrix, suggesting that matrix heparan sulfate acts as a growth inhibitor. Consistent with this, biochemical analysis showed that the adult matrix contained a higher percentage of heparan sulfate compared with neonatal or neointimal matrix. These results suggest that autocrine production of heparan sulfate proteoglycans may play an important role in growth regulation of vascular smooth muscle cells during normal vascular development and differentiation as well as in pathological response to injury.

Age Factors↗