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Biomedical subjects

D Schwartz

Publications and source records attributed to D Schwartz.

At least 343 records · Page 19Linked to original sources
PubMed1980

[Methodological approach of a retrospective study on 484 fertile and 2 768 infertile men (author's transl)].

One possible method to study male factors in fertility is the retrospective comparison of groups of fertile and infertile men. Such a study based on 484 fertile and 2 768 infertile men enables us to point out an increasing risk of infertility with decreasing sperm counts and percentage of motile spermatozoa and with increasing abnormal forms. However the increase in relative risk is sharper for the patients who consulted twice or more than those who came for the first time. This difference might in part be explained by the fact that the former had a longer duration of infertility or that the couple infertility had less often a female origin. Consequently detailed information on this subject must be taken into account in studies on fertility.

Fertility↗
PubMed1980

In vitro translation of maize ADH: evidence for the anaerobic induction of mRNA.

Total cellular RNA from anaerobically stressed maize seedling roots was used to stimulate in vitro translation of authentic maize alcohol dehydrogenase (ADH) in a rabbit reticulocyte lysate system. Total products from such reactions were displayed on NEPHGE-SDS two-dimensional gels and the Adhl-specific translation products were identified by using RNA from sib seedlings segregating for Adhl charge and size variants. The application of a rapid RNA isolation procedure allowed the efficient isolation of biologically active RNAs from small amonts of seedling material. Maize ADHs translated in vitro are identical in size to in vivo ADH. Further, no ADH was detected in the products of an in vitro translation reaction stimulated by total RNA from aerobically grown seedlings. This suggests that induction of ADH protein by anaerobic stress is accomplished by production of Adh mRNA rather than activation of sequestered mRNA. The mRNAs for maize ADH1 and ADH2 are among a small class of mRNAs induced during anaerobiosis.

Alcohol Oxidoreductases↗
PubMed1980

The success of A.I.D. and semen characteristics: study on 1489 cycles and 192 ejaculates.

A comparison was made between successful (167) and unsuccessful (1322) insemination cycles in order to evaluate the role in conception of different semen characteristics. The most important semen variable was found to be post-thaw motility: the success rate per cycle increased from 7% when post-thaw motility was less than or equal to 40% to 17% when it was greater than or equal to 65%. Multiple inseminations in a cycle increased the success rate primarily when semen quality was poor. The results of this study show how and to what degree efficacy in A.I.D. can be improved by a judicious choice of the semen to be utilized and the number of inseminations to be practiced.

Adult↗
PubMed1980

Characterization of bovine anterior-lens-capsule basement-membrane collagen. 2. Segment-long-spacing precipitates: further evidence for large N-terminal and C-terminal extensions.

Collagen extracted from bovine anterior lens capsule basement membrane under minimally degradative conditions can be precipitated in the form of segment-long-spacing crystallites. Positive and negative stain preparations of these precipitates, using uranyl acetate, show the crystallites to have an asymmetric band pattern, indicating unidirectional orientation of all molecules in each crystallite. Non-banded globular masses appear at both ends of most of the crystallites, giving the segment-long-spacing aggregates the form of dumbells, with a total length of 300 nm. Repeated pepsin digestion removes first one then both globular regions leaving the helical region intact but with a length still equal to 300 nm. It thus appears that the pepsin-susceptibile protein is folded back over and covers the ends of the helical regions. Preparations with the most intact end regions tend to aggregate in fibrous segment-long-spacing form, that is, in end-interacted strings or nets. The very prominent molecular end-region interaction suggests a similar filamentous but non-periodic organization within native basement membrane.

Animals↗
PubMed1980

Degradation of basement-membrane collagen by neutral proteases from human leukocytes.

A neutral extract from human leukocytes was shown to have proteolytic activity which could degrade triple-helical basement membrane collagen from bovine lens capsules into specific triple-helical sub-fragments. The enzymes responsible is not identical to the leukocyte collagenase active against interstitial collagen types I, II and III. After denaturation, the neutral protease reaction products showed three major peptides with molecular weights of 70,000, 50,000 and 30,000, by dodecylsulphate gel electrophoresis analysis. Electron microscopic observation and viscosity measurements showed the initial twice-pepsinized collagen to be comprised of intact rod-like molecules about 300 nm long. The fragments produced by the protease were also triple-helical and were resistant to the action of trypsin at 20 degrees C. The fragments were completely degraded by purified bacterial collagenase or by raising the reaction temperature above the melting temperature of the basement membrane collagen during incubation with leukocyte extract. Enzyme activity has its pH optimum between 7 and 9, EDTA, EGTA and 1,10-phenanthroline (metal-chelating agents) completely inhibited enzyme activity, as did serum. Partial inhibition of the activity was obtained with phenylmethylsulfonyl fluoride and soybean trypsin inhibitor.

Animals↗
PubMed1980

Artificial insemination with frozen sperm: protocol, method of analysis and results for 1188 women.

The experience of a sperm bank during a five year period is reported. Artificial insemination by donor (AID) was carried out on 1188 women using frozen sperm prepared in doses of 0.25 ml. A single insemination was called for during each of the first two cycles. The patients were classified in 4 categories: lost to follow-up, successes, dropouts and open cases. The success rate per cycle was about 10 per cent and was very stable for each of the first 12 cycles. The cumulative success rate was calculated by the life table technique adapted for AID analysis. A theoretical success rate (without dropouts) and an effective success rate (with dropouts) were calculated. These two rates were 68 and 55 per cent respectively after 12 cycles. The median delay to conception was 7 and 9 cycles, respectively, under theoretical and effective conditions. The spontaneous abortion rate (17 per cent) and sex-ratio (106 males for 100 females) resemble those for natural reproduction but the success rat per cycle was markedly lower even after adjusting for age.

Adult↗
PubMed1980

[The concept of fecundability in the etiologic, diagnostic and therapeutic approach to infertility (authors' transl)].

The infertility of a couple is most often attributable not to sterility but rather to subfertility in either one or both of the partners. Accordingly, the study of fertility in couples must be quantitative. Fertility can be appreciated by different indices; the most common being the fecundability, which is the probability (P) of a couple conceiving in a given menstrual cycle. It is a "risk", a concept of acknowledged value in public health. The standard epidemiological methods have led to the identification of its mean value which is of the order of 25% in our countries for young couples. It varies greatly from one couple to an other and with the numerous male and female factors on which it depends. The probability of couple obtaining a pregnancy seems to be the result of a lottery which recommences at each cycle with a probability of success P: a single formula shows how this probability increases both with P and with time. Thus, only by taking into consideration simultaneously male fertility, female fertility as well as time, an essential factor that is too often forgotten, is one able to rationally approach the etiology, diagnosis and therapeutics in case of infertility.

Adolescent↗
PubMed1979

Mutational study of the alcohol dehydrogenase-1 FCm duplication in maize.

The alcohol dehydrogenase-1 FCm (Adh-FCm) duplication in maize was subjected to ethyl methanesulfonate (EMS) mutagenesis. Of the mutants recovered, eight produced ADH polypeptides with altered electrophoretic mobility. Four produced new mobilities of the progenitor F with no change of the Cm molecule; the remainder altered only the Cm enzyme. No cases were found in which the electrophoretic mobilities of the two types of subunits were simultaneously altered, and no complete nulls lacking both F and Cm were recovered. These observations confirm the duplicate nature of the FCm complex.

Alcohol Oxidoreductases↗