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Biomedical subjects

M Chvapil

Publications and source records attributed to M Chvapil.

At least 127 records · Page 7Linked to original sources
PubMed1978

Cryocoagulation of the endometrium at the uterine cornua.

A cryoprobe that will produce coagulation necrosis and subsequent scar formation of the cornual areas of the uterus has been tested. A discussion is made of the developmental program, including the design of the instrument, efficacy and safety testing in baboons, and preliminary investigations of the safety of this procedure in man.

Animals↗
PubMed1978

Identification of ejaculate derived propylamine found in collagen sponge contraceptives.

Propylamine is identified as one of the compounds present in odoriferous intravaginal contraceptive sponges from sexually active women. This compound also appears in samples of human ejaculate incubated at 37 degrees C for seven days. We have identified propylamine by gas liquid chromatography, mass spectroscopy and as N-propylbenzoylamide. Evidently the compound forms enzymatically from spermine and spermidine. We believe that this is the first time that propylamine has been identified as forming from human tissue.

Collagen↗
PubMed1978

Urinary excretion of beta-aminopropionitrile and cyanoacetic acid.

Human serum did not convert beta-aminopropionitrile (BAPN) to the deaminated, nonlathyrogenic metabolite, cyanoacetic acid (CAA). Instead, its enzymic activity for oxidizing benzylamine was inhibited by BAPN (I50 = 2 X 10(-3) M). BAPN was found in the urine within one hour of oral administration. Oral 250 mg BAPN at 6-hr intervals each day for 21 days resulted in urinary BAPN recoveries approximating 16% of the total dose. BAPN was not detected in urine in specimens collected later than 7 hr after cessation of BAPN dosage. Urinary CAA appeared more slowly than BAPN and increased gradually to approximately three times that of urinary BAPN. After BAPN was discontinued, there was prolonged urinary excretion of BAPN-derived CAA. These along with earlier findings in experimental animals suggest that unexcreted BAPN is sequestered in tissues where it is metabolized to CAA before slowly released.

Acetates↗
PubMed1978

Studies on vaginal malodor. I. Study in humans.

Forty-two percent of collagen sponges tested as an intravaginal barrier contraceptive method developed malodor when retained for 5 days. Only 4% developed odor when the sponge was removed within 24 hours after intercourse, rinsed, and reinserted. While sexually active volunteers found odor in 37% of the sponges, odor formed only in 4% of the sponges worn by sexually inactive users. No difference in the rate of odor formation was found when neutral pH (7.0) and acid pH (3.4) collagen sponges were tested, although we believe that a pH 3.4 is too acid and promotes odor formation. The optimal pH of the sponge should be 4.5 to 5.5. Malodor was efficiently extracted from sponges by washing in acid milieu of tap water and vinegar or 0.1 M acetate buffer, pH 4.0. Alkali extraction procedures were ineffective, and lukewarm water was slightly less effective than acid extraction of odor. At the time of malodor development, the high content of polyamines (putrescine, spermine, spermidine) in the ejaculate decreased to undetectable values. We conclude that the ejaculate is the major source of malodor formation in intravaginally worn collagen sponges. Removal, rinsing optimally in vinegar solution, and reinsertion within 24 hours after intercourse reduces the chance of malodor formation.

Adult↗
PubMed1977

Stimulation of the activity of prolyl hydroxylase in 3T3 fibroblasts by 1,10-phenanthroline.

In confluent cultures of 3T3 fibroblasts, incubated for 24 h with 1,10-phenanthroline at 10(-5)--10(-9) M, the activity of prolyl hydroxylase was significantly increased. 1,10-Phenanthroline was inhibitory at concentrations greater than 10(-4) M. The stimulatory effect of 1,10-phenanthroline manifests itself after 6 h incubation and increased with time up to 48 h. 2,2'-dipyridyl and 5,6-dimethyl-1,10-phenanthroline were also stimulatory; a nonchelating analog, 1,7-phenanthroline had no effect. Cycloheximide did not modify the 1,10-phenanthroline effect. The stimulatory effect does not seem to depend on the shift of an inactive precursor of prolyl hydroxylase to an active form because 1,10-phenanthroline was shown to be ineffective in logarithmically growing cells. While dialysis of washed and homogenized cells significantly increased prolyl hydroxylase activity in cell extracts, undialyzed 1,10-phenanthroline treated samples exhibited higher prolyl hydroxylase activity than dialyzed controls. These data suggested to us that 1,10-phenanthroline and other chelating agents may be forming complexes with certain metal ions or protein-metal ions which are inhibitory towards prolyl hydroxylase.

2,2'-Dipyridyl↗
PubMed1977

Effect of collagen crosslinking on the rate of resorption of implanted collagen tubing in rabbits.

Collagen tubes were tanned with glutaraldehyde for different periods of time. Some were oxidized with periodate and sterilized with either 60Co (1.5 Mrad) or propylene oxide. The tubes were coated with polyfilamentous polyester fabric, filled with x-ray contrast material, and implanted subcutaneously in rats and rabbits. Rate of resorption was ascertained by x-ray procedure of progressive leakage of contrast material. A close relation between tanning time of the collagen fabric-combined prostheses and rate of their resorption in subcutis was found in both rats and rabbits. In rabbits, however, the implants were resorbed at a significantly faster rate than in rats. No effect of oxidation of collagen on the resorption was observed. Collagen tubes tanned for shorter time periods and sterilized with propylene oxide were more resistant to degradation than those sterilized with irradiation. This difference was absent, however, with material tanned for longer times. The mechanism of resorption of implanted collagen tubes was studied by morphological methods. The role of inflammatory cells in resorption is documented. The paper indicates the advantages as well as limits of the x-ray method of studying the resorption rate of biodegradable materials.

Animals↗
PubMed1977

Collagen sponge: theory and practice of medical applications.

Theoretical as well as practical-clinical applications of one form of collagen (collagen sponge) as a biodegradable material is reviewed. The role of porosity of the sponge and surface characteristics of the meshwork in relation to cell ingrowth are considered essential features of collagen sponge. Rate of resorption and antigenicity could be controlled by graded crosslinking of collagenous framework. Four basic examples of clinical use of collagen sponge are presented: as wound (burn) dressing material, as a matrix, for bone and cartilage repair, as an intravaginal contraceptive diaphragm, and as surgical tampons.

Antigens↗
PubMed1977

Effect of zinc on peritoneal macrophages in vitro.

Rat peritoneal macrophages incubated in a medium with 10% autologous serum showed 50% inhibition of O2 consumption by 0.4 mM zinc only when activated by yeast. Zinc ions had no effect on resting macrophages. The inhibitory efficiency of zinc depended on the ratio of yeast particles to macrophages; with more activated cells, the inhibition was less. The multiple-shaped intact macrophages changed into rounded cells in the presence of 0.1 and 0.5 mM Zn2+ as shown by photomicrography and scanning electron microscopy. When the incubation medium was replaced by zinc-free medium, cells recovered and became irregularly shaped. The reversibility of zinc effect on cell morphology corresponded with uptake and release of zinc by macrophages. The presence of serum in the medium interfered with the magnitude of zinc uptake by macrophages. We conclude that besides already reported effects of zinc on mast cells, platelets, and granulocytes, zinc ions also inhibit some functions of macrophages.

Animals↗
PubMed1977

Effect of paraquat on rat lung prolyl hydroxylase.

Acute administration of Paraquat (25 mg/kg, I.P.) was found to significantly increase prolyl hydroxylase in rat lung 7 days following treatment. There was no change in total collagen at this time point. At 21 days following drug treatment, total collagen was significantly elevated while prolyl hydroxylase activity had returned to control level.

Animals↗