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Biomedical subjects

M Chvapil

Publications and source records attributed to M Chvapil.

At least 145 records · Page 8Linked to original sources
PubMed1977

Inhibition of some functions of polymorphonuclear leukocytes by in vitro zinc.

In granulocytes isolated by dextran sedimentation from dog blood, the O2 consumption, phagocytosis of yeast particles, and E. coli killing were tested in Tris-guffered saline medium with additions of Zn++, Mg++, and other divalent cations and in the presence or absence of plasma. Zn++ inhibited all three cell functions in a concentration-related manner only in the presence of 1.2 mM Mg++. Without Mg++ in the medium the lower concentrations of Zn++ (17 to 67 muM) were stimulatory; 83 muM Zn++ concentration was inhibitory. A close association was found between the inhibitory effect of Zn++ and the actual content of zinc in the cell: (1) the uptake of zinc from the medium was minimal during the first minute, where no Zn++ effect on cell functions was manifest, (2) when zinc-loaded cells with inhibited activity were washed and reincubated for at least 15 minutes in zinc-free medium, almost 95 per cent of the zinc was washed out and cell activity was normalized. This indicated reversibility of the zinc effect, (3) in the presence of increasing concentrations of autologous plasma in the medium, the effect of zinc was proportionally less pronounced and at the same time uptake of zinc by cells was decreased. Of the six divalent cations studied at 50 muM concentration and in the presence of Mg++, only Zn++ was inhibitory, Se and Co were inactive, and Mn and Cu stimulated O2 consumption of latex-activated granulocytes. We conclude that zinc ions, in the presence of Mg++ in the medium, inhibit various functions of dog peripheral granulocytes and this effect is closely associated with zinc uptake by the cells. The effect is reversible and specific for this metal.

Animals↗
PubMed1977

Morphologic, biophysical, and biochemical consequences of ligation of the common biliary duct in the dog.

Common biliary ducts of 32 adult mongrel dogs were ligated for a period of 2 days to 6 weeks. Sham-operated animals served as controls. Bile ducts were removed at sacrifice, and biophysical, morphologic, and biochemical parameters were measured. Our study shows that biliary duct ligation results in an immediate increase of intraductular pressure and is followed quickly by significant increase in the rate of collagen synthesis and the activity of prolyl hydroxylase. Histologic data show subepithelial inflammation followed by marked increases in periductular fibrosis. This fibroproliferative response is paralleled by peak levels of prolyl hydroxylase activity at 2 weeks prostligation. Paradoxically, bile ducts continuously distend throughout the ligation period despite increased fibroplasia. We present here the first topographic (SEM) study of normal and ligated common bile duct epithelium. Following 2 weeks of ligation large crater-like fenestrae are seen ductular epithelial surfaces. This is followed by focal epithelial sloughing. We speculate that the continuous distention and epithelial necrosis seen in the present study may be due to biliary stasis and/or subepithelial infiltration of bile through epithelial fenestrae. This hypothesis is supported by our studies which show that collagen extractibility is markedly increased by the addition of bile to the homogenate.

Animals↗
PubMed1976

Early changes in the arterial wall of chickens fed a cholesterol diet.

A total of 160 1-2 day old chickens were fed a 2% cholesterol diet for a period of 8 to 42 days and compared with an equal number of controls. Aortas were analyzed for various indexes of reactivity of connective tissue, cholesterol content and scanning electron microscopy (SEM) characteristics of the endothelial lining. Cholesterol feeding for a period up to 6 weeks resulted in doubling the level of serum cholesterol. It was, however, without effect on the activity of prolyl hydroxylase, lysyl oxidase, collagenase and collagen content in the aortic wall. As early as 3 weeks of feeding significant changes occurred in total and esterified cholesterol content. At the same time endothelial cells were characteristically contracted with several long cytoplasmic elongations and protrusions. A significant decrease of activity of the above enzymes was found in aortic tissue with increased age of the chicken. Collagen content in aortas increased with age of chickens. It is concluded that cholesterol as an atherogenic agent induces marked changes in endothelial cells and lipids of chicken aorta at earlier periods, prior to the activation of connective tissue.

Animals↗
PubMed1976

A comparative study of four materials in local burn care in rabbit model.

In rabbits, a second-degree burn model with partial tangenitial excision of necrotic tissue was used to compare four dressing materials for effectiveness of promoting wound healing. The time of complete epithelization of the 2 X 4 cm large defect, changes in wound area, adherence of the dressings to the wound, and histology of the wound bed and dressings were measured. Dressings were changed twice weekly. Experiments showed that as a local dressing for burns, non-laminated collagen sponge was significantly better than pigskin or xeroform. Infection did not occur under it. It was very adherent to the burn wound and was actively permeated by inflammatory cells. This factor allowed early debridement of the wound. Effective debridement was probably responsible for the shorter healing time shown. Laminated collagen sponge was the poorest of the four dressings tested.

Animals↗
PubMed1976

An intravaginal contraceptive diaphragm made of collagen sponge: new old principle.

This study presents a theoretical background for a new intravaginal contraceptive. A highly resilient and liquid-absorbent collagen sponge in the form of a cup is self-administered in the upper vault of the vagina, where it is retained for several days to form a mechanical barrier against sperm. The high fluid-binding capacity contributes to the trapping and immobilization of sperm within the sponge. Other methods enhancing the retention and spermicidal effect of the sponge are discussed. Clinical testing of the sponge is in progress.

Biocompatible Materials↗
PubMed1976

The acceptance of the collagen sponge diaphragm as an intravaginal contraceptive in human volunteers.

Two types of highly resilient and liquid-absorbent collagen sponge contraceptives (CSC) in the shape of cylindrical cups (6 cm wide and 2.5 cm thick) were evaluated for acceptance as an intravaginal contraceptive method for a period of 3 months in 27 volunteers. Parameters such as retention, odor, irritation, itching, discharge, and convenience for the user and her sexual partner were tested. Average retention time was 7 to 9 days (range, 2 to 28 days); still, most sexually active volunteers preferred to remove the CSC every 3 to 4 days, rinse them in tap water, and reinsert them. Odor was noticed by users in 4% of the tested sponges and in 30% of all volunteers by medical personnel at the time of removal of the CSC from the vagina. No irritation, itching, or discharge was reported. The CSC alone did not cause any inconvenience to the user or partner, while the CSC with inserted rubber ring was felt by both partners and was found to be dislocated. This study indicates good acceptance of the CSC in intravaginal use. Studies to evaluate the efficacy of collagen sponges as mechanical contraceptive barriers are in progress.

Collagen↗