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Biomedical subjects

M Knorr

Publications and source records attributed to M Knorr.

89 records · Page 5Linked to original sources
PubMed1985

High density lipoproteins--modulators of the calcium channel?

It has recently been shown that human red blood cells possess a voltage-independent calcium channel which can be influenced by in vitro modification of the membraneous cholesterol content. To determine whether there is also a link between plasma lipids and the calcium influx through this channel under in vivo conditions, the calcium influx was measured in red blood cells from 51 male donors (aged 41 +/- 5 years). The influx through the channel was defined as the nitrendipine (15 mumol/l)-inhibitable part of 45Ca2+ influx. The Ca(2+)-ejecting ATPase was inhibited by vanadate. The results demonstrate a strong inverse relationship (r = -0.81; P < 0.001) between the plasma concentration of high density lipoproteins (HDL) and 45Ca2+ influx. No significant correlation was found between 45Ca2+ influx and triglycerides, low density lipoproteins (LDL), very low density lipoproteins (VLDL), total plasma cholesterol or extracellular electrolytes (K+, Na+, Ca2+, Mg2+). The results indicate that HDL are involved in the modulation of the calcium channel and provide a link between the cellular cholesterol turnover and the calcium influx in the pathogenesis of atherosclerosis and hypertension.

Adult↗
PubMed1983

Sodium and calcium in lymphocytes and erythrocytes in essential hypertension.

The present study compared protein-related sodium concentrations in lymphocytes with the sodium and calcium activities in erythrocytes from 12 untreated patients with essential hypertension and 15 normal control subjects. It appeared that protein-related Na+ in lymphocytes was elevated about threefold in essential hypertensives. Comparable increases were also noted in intracellular Na+ and Ca2+ activities. The correlation between Na+ in lymphocytes and in erythrocytes was not close. These results suggest that the determination of protein-related Na+ in lymphocytes discriminates between normotensives and essential hypertensives as well as measurements of ion activities in erythrocytes. Altered intracellular ion binding may be partly responsible for the changes in intracellular protein-related Na+.

Calcium↗
PubMed1979

[Seasonal and periodic rhythms of infectious diseases (author's transl)].

The causes of epidemics are plainly not the pathogens alone as was initially assumed by Koch's school, predisposition and constitution of the population proved to be equally important. Ever since ancient times problems linked with the "constitutio epidemica" have been topical; the "physis", the "natura hominis" and the invironment of man play an increasingly important role in the symptomatology of disease, as can be gathered from such early documents as the "Corpus hippocraticum". Fracastoro distinguished between contagious and non-contagious epidemics. The casual organisms were considered to be miasmas -- noxious emanations -- or "contagia" i.e. likewise toxic substances. Questions concerning the origin of these miasmas turned attention to the environment (air, soil, water) and even led to astrological medicine. Not until the Renaissance were attempts made to differentiate the usual global words for epidemic, such as "loimos", "lues" and "pestis" with the result that a symptom was used more and more to designate a disease. For example, the symptom fever led to the designation "three-day fever" or "four-day fever", "typhus fever". This terminology made a differential diagnosis difficult to establish, thwarted selection measures to check epidemics and the medical world was thus helpless in explaining the causal agents and the phenomena of epidemics. This is illustrated by some epidemiological examples (ergotism, scurvy, yellow fever, English sweat, diphtheria and malaria). In this connection the "morbus novus", the transformation of the pathogen and the change of the pathogen is discussed. Many questions still left unanswered regarding the seasonal incidence, the fluctuation and disappearance of epidemics over decades or even centuries lead more frequently to sociomedical considerations with respect to the victims of epidemics, their predisposition, constitution and environment exposure term "hospital gangrene" with the modern term "hospitalism", we are not dealing with a transformation but a change of the pathogen. The impressive effects produced by antibiotics resulted in carelessness and along with the unprecedented advances in medicine and engineering we forgot to bear in mind that almost all great steps forward have an adverse side. Hygiene and practical medicine have only made a modest beginning in establishing the contact which should indeed be a matter of course in the hospital.

Adult↗
PubMedDate not supplied

Effect of cytokines on regulation of the production of transforming growth factor beta-1 in cultured human Tenon's capsule fibroblasts.

PURPOSE: Transforming growth factor-beta1 (TGF-beta1) is thought to play a pivotal role in the regulation of the wound healing process after glaucoma filtering surgery. The aim of the present study was to investigate whether platelet-derived growth factor isoforms (PDGF-AA, PDGF-BB), basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), interleukin-1beta (IL-1beta) and transforming growth factor-beta1 (TGF-beta1) modulate the production of latent and/or active TGF-beta1 by cultured human Tenon's capsule fibroblasts (HTF). METHODS: Human Tenon's capsule fibroblasts were seeded at two different densities (30 cells/mm2 and 150 cells/mm2) and stimulated for five days with PDGF-AA, PDGF-BB, bFGF, EGF, IL-1beta and TGF-beta1. Control cells were treated with serum-free medium (WM/F12). The concentrations of latent and active TGF-beta1 in the medium were determined using an immunoassay before and after activation of TGF-beta1 by transient acidification. RESULTS: The concentration of latent TGF-beta1 in conditioned media from HTF seeded at high density (150 cells/mm2) significantly increased after stimulation with 5 ng/ml TGF-beta1 (151.5 +/-41.7 pg/ml) or 10 ng/ml IL-1beta (45.7+/-8.1 pg/ml). The concentration of active TGF-beta1 in conditioned media also significantly increased after stimulation of HTF with 5 ng/ml TGF-beta1 (48.4+/-27.5 pg/ml). CONCLUSIONS: The present results indicate that TGF-beta1 is the most potent inducer of its own synthesis in HTF. Activation of an autocrine TGF-beta1 loop may play a role in the wound healing response after glaucoma filtering surgery.

Cells, Cultured↗
PubMedDate not supplied

Evaluation of glaucomatous visual field loss with locally condensed grids using fundus-oriented perimetry (FOP).

PURPOSE: We compared detection rates of glaucomatous visual field defects (VFDs) between a conventional rectangular stimulus grid and locally condensed test point arrangements in morphologically suspicious regions. METHODS: Humphrey Field Analyzer model 630 (HFA I, program 30-2 with a rectangular 6 degrees x 6 degrees grid) was used as the conventional perimetric method. Individual local test-point condensation was realized by fundus-oriented perimetry (FOP) on the Tuebingen Computer Campimeter (TCC). RESULTS: Of a total of 66 glaucoma patients, or suspected sufferers, 23 showed normal findings and 27 showed pathological findings with both methods. In 15 cases we found normal visual fields in HFA 30-2, whereas FOP revealed early glaucomatous functional damage. Only one case showed pathological HFA results, while FOP was normal. Detection rates of VFDs significantly differed between the two methods (p < 0.001; sign test). CONCLUSIONS: FOP, using individually condensed test grids, significantly increases detection rates of glaucomatous VFDs in morphologically suspicuous areas compared with a conventional HFA 30-2 technique using equidistant rectangular (6 degrees x 6 degrees) test point arrangements.

Adolescent↗
PubMedDate not supplied

In vitro effect of ascorbic acid on the proliferation of bovine scleral and Tenon's capsule fibroblasts.

The success of glaucoma filtration surgery depends mainly on an incomplete wound healing process in the area of the fistula. Since Kornblueth and Tenenbaum's investigations in 1956 it has been known that aqueous humour has intrinsic antiproliferative properties. It is assumed that ascorbic acid is involved in the regulation of the wound healing process after filtration surgery. To evaluate the antiproliferative effect of ascorbic acid in vitro, we used cultured fibroblasts of bovine Tenon's capsule and bovine sclera. Incubation of these cells with ascorbic acid at concentrations ranging from 0.5 to 3 mM/L led to dose-dependent inhibition of cell proliferation. The half-maximal inhibitory concentration was 1.0 mM/L for both cell types. Physiological concentrations of ascorbic acid may be valuable in the pharmacological prevention of failure of glaucoma filtration surgery. However, extensive clinical investigations are needed to clarify whether topical intraoperative or postoperative as well as oral administration of ascorbic acid inhibits fibroblast proliferation after glaucoma filtration surgery.

Animals↗