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M Feifel

Publications and source records attributed to M Feifel.

6 recordsLinked to original sources
PubMed1983

Structure activity correlation for diuretic furosemide congeners.

The structure activity correlation of several groups of anthranilic acid derivatives was studied. 59 compounds, most of them possessing the anthranilic acid moiety, were synthesized and tested for diuretic and saluretic activities. Equations correlating the biological activities of these compounds with their physicochemical constants suggest positive dependence of the diuretic activity on log P (octanol:water partition coefficient). It is concluded that, within limits, the variation in biological activity is primarily governed by the lipophilicity of the molecule, and further increase in log P value will not enhance this activity.

Animals↗
PubMed1982

Acid extraction of acrosin from human spermatozoa pretreated by different physicochemical methods.

Washed human spermatozoa were subjected to different physicochemical methods, followed by acid extraction of the sperm acrosomes to dissolve acrosin. The acrosin activity of the sperm pellet and the supernatant was determined by benzoyl arginine ethyl ester/alcohol dehydrogenase (BAEE/ADH) assay to calculate the total acrosin activity in mU/10(6) spermatozoa. Membrane-active and zymogen-activating agents increased the total acrosin activity 50%-200% compared to acid extraction alone. Similar results were obtained by osmotic shock, sonication and treatment with glass beads. Snap freezing of unprotected spermatozoa in liquid nitrogen yielded a fivefold increase in total acrosin activity, thus demonstrating that this is the method of choice for optimal acrosin extraction. The possibility is discussed as to whether acrosomal membrane alterations with improved solubilization of membrane-bound acrosin and/or conformational changes and/or zymogen activation are responsible for the considerable increase observed in acrosin activity.

Acids↗
PubMed1981

Inhibitors of acrosomal proteinase as antifertility agents. A problem of acrosomal membrane permeability.

In vitro studies were performed to investigate the accessibility of acrosin to various proteinase inhibitors inside the intact acrosome of testicular, ejaculated, and uterine human spermatozoa. As test system the gelatin plate assay was used. For this assay it was shown formerly that a correlation exists between the size of the digested lysis areas (halo formation) and acrosin activity estimated with synthetic substrates. In addition, saturation of the gelatin substrate membranes with acrosin inhibitors including highly specific ones before application of spermatozoa completely prevented halo formation indicating that the gelatinolytic activity of human spermatozoa is caused exclusively by acrosin. When human spermatozoa were incubated with various acrosin inhibitors (concentration: 1 mmol/l) prior to application to the gelatin membrane, reduction of halo formation could not be observed, however. This result indicates that most of the tested acrosin inhibitors (9 naturally occurring protein inhibitors, 2 microbial peptide inhibitors, 19 synthetic inhibitors) were unable to penetrate the acrosomal membranes of testicular, ejaculated, and uterine human spermatozoa. Only 2 inhibitors caused moderate up to complete inhibition of the gelatinolytic activity of the spermatozoa if applied in concentrations between 1 and 10 mmol/l: the proteinase inhibitor aprotinin and the synthetic inhibitor NPGB (4-nitrophenyl 4-guanidinobenzoate). Obviously, human acrosomal membranes seem to be especially impenetrable to proteins, polypeptides, and synthetic agents. Those acrosin inhibitors penetrating the human sperm head membranes are either too toxic or the local concentration necessary for effective acrosin inhibition in vivo cannot be achieved within the male or female genital tract secretions. Therefore, acrosin inhibitors cannot be used for human contraception at present. Thus it is mandatory to continue the search for suitable acrosin inhibitors with low toxicity easily penetrating into the intact sperm acrosome.

Acrosome↗
PubMedDate not supplied

Low acrosin activity in polyzoospermia.

Compared to normozoospermic men total sperm acrosin activity is considerably decreased (-59,1%) in patients with polyzoospermia indicating a functional defect of the proteolytic potential of the sperm acrosome, which may be responsible for the reduced fertility observed in this group of patients.

Acrosin↗
PubMedDate not supplied

[Inhibitors of acrosomal proteinase as antifertility agents. A problem of acrosomal membrane permeability (author's transl)].

In vitro studies were performed to investigate the accessibility of acrosin to various proteinase inhibitors inside the intact acrosome of testicular, ejaculated, and uterine human spermatozoa. As test system, the gelatin plate assay was used. For this assay, it was shown formerly that a correlation exists between the size of the digested lysis areas (halo formation) and acrosin activity estimated with synthetic substrates. In addition, saturation of the gelatin substrate membranes with acrosin inhibitors including highly specific ones before application of spermatozoa completely prevented halo formation indicating that the gelatinolytic activity of human spermatozoa is caused exclusively by acrosin. When human spermatozoa were incubated with various acrosin inhibitors (concentration: 1 mmol/1) prior to application to the gelatine membrane, reduction of halo formation could not be observed, however. This result indicates that most of the tested acrosin inhibitors (9 naturally occurring protein inhibitors, 2 microbial peptide inhibitors, 19 synthetic inhibitors) were unable to penetrate the acrosomal membranes of testicular, ejaculated, and uterine human spermatozoa. Only 2 inhibitors caused moderate to complete inhibition of the gelatinolytic activity of the spermatozoa if applied in concentrations between 1-10 mmol/l: the proteinase inhibitor aprotinin and the synthetic inhibitor NPGB (4-nitrophenyl 4-guanidinobenzoate). Obviously, human acrosomal membranes seem to be especially impenetrable to proteins, polypeptides, and synthetic agents. Those acrosin inhibitors penetrating the human sperm head membranes are either too toxic or the local concentration necessary for effective acrosin inhibition in vivo cannot be achieved within the male or female genital tract secretions. Therefore, acrosin inhitibors cannot be used for human contraception at present. Thus, it is mandatory to continue the search for suitable acrosin inhibitors with low toxicity easily penetrating into the intact sperm acrosome.

Biology↗