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Biomedical subjects

R Singer

Publications and source records attributed to R Singer.

At least 91 records · Page 5Linked to original sources
PubMed1983

ATP contents of human semen, seminal plasma and isolated sperm at time intervals after ejaculation.

1. ATP was estimated in 105 samples of human semen, seminal plasma and sperm of normozoospermic and oligozoospermic origins at time intervals after ejaculation. 2. In semen with sperm counts up to 40 millions per ml and in seminal plasma, ATP levels were lower than in specimens with higher sperm counts. 3. In isolated sperm, the ATP content decreased with the increase in sperm density. 4. The decrease in ATP after 24 hr was the highest in sperm, lower in semen and the lowest in seminal plasma, being maximal in specimens with high sperm counts.

Adenosine Triphosphate↗
PubMed1983

Unplanned nutrition education in the schools: sugar in elementary reading texts.

Analysis of food content in 1,666 readers, prereaders and reading workbooks for grades K-3 revealed an undue emphasis upon sweets in both words and pictures. Cake alone accounted for one of every 12 food appearances. While fruits and vegetables were pictured slightly more often than sugar-rich foods, they were related to actual food consumption far less frequently than sweets. By publisher, other food groups accounted for 10% or less of all food pictures and 15% or less of all food words. Snacks, treats and parties appeared more often as occasions for eating than regular meals, excluding picnics. Families were rarely presented eating together and little attention was devoted to the nutritional value of food. Knowledge children acquire from the media and other sources before attending school has been identified as a force counteracting nutrition education, but unintended messages conveyed in K-3 readers also may work against the promotion of healthy eating habits. Reading texts should be screened for nutritional content before adoption and revised to reduce the appearance of sweets in accord with national dietary goals. Nutrition education must extend beyond teaching the basic four food groups to help children recognize how their food choices are affected by environmental influences, inside as well as outside of school.

Books↗
PubMed1983

Deoxyribonuclease activity in human seminal fluid.

Deoxyribonuclease (DNase) activity was examined in the whole and two split fractions of human seminal fluid from normospermic, oligozoospermic, and azoospermic origins as well as in sonicates of isolated sperm after freezing and thawing of samples and at various pH values of substrates. The method consisted in the measurement of digested areas in plates containing herring sperm deoxyribonucleic acid (DNA). No correlation was found between DNase activity (875 +/- 22 (SE) ng/ml) and seminal fluid quality. The enzyme activity was significantly lower in the second split portion (764 +/- 43 ng/ml) as compared to the first (971 +/- 41 ng/ml). Sonicates of washed sperm were inactive. It is suggested that DNase activity derives from the epididymis and possibly from the vas deferens where it participates in the decomposition of DNA from dead cells.

Deoxyribonucleases↗
PubMed1983

Distribution of sialic acid in human sperm membranes.

Sialic acid was estimated both chemically in populations of heads and tails of spermatozoa from normospermic human seminal fluid and by transmission electron microscopy, using a specific labeling technique. The results of both procedures show that sialic acid is located exclusively in the head plasma membrane and in the acrosomal membranes. It is suggested that localization of sialic acid close to that reported for neuraminidase in sperm might be of importance in the fertilization process.

Acrosome↗
PubMed1983

Sialic acid content of human spermatozoa and seminal plasma in relation to sperm counts.

Sialic acid levels were determined in spermatozoa and seminal plasma of 47 semen samples divided into two groups according to sperm counts. Group 1, up to 40 x 10(6) sperm/ml seminal fluid and group 2, above 40 x 10(6) sperm/ml seminal fluid. The content of sialic acid in spermatozoa ranged from 4.4-28.1 micrograms/10(8) spermatozoa and from 70-95 mg/100 ml seminal plasma. Sialic acid was significantly higher in sperm and lower in seminal plasma of group 1 as compared to group 2. The lower content of sialic acid in seminal plasma might have a deteriorating effect on structural integrity of sperm.

Humans↗
PubMed1983

Hyaluronidase activity in untreated human semen and following laboratory manipulations.

Hyaluronidase activity was examined in 104 oligospermic and normospermic human semen specimens promptly after liquefaction, after repeated cycles of washings with a solution containing 1.3 M sucrose and 0.15 M NaCl, and after freezing and thawing. We assessed enzyme activity by measuring areas of the digestion of substrate (hyaluronate). After washing the oligospermic and normospermic semen specimens twice 34%-43% enzyme activity was still present in the sedimented sperm as compared to the initial values. Following additional washings no enzyme activity could be detected. Freezing and thawing of semen increased enzyme activity by 40%-50%, respectively, after the second cycle whereas further treatment did not increase the enzyme activity rate. It is suggested that two types of hyaluronidase are present in human spermatozoa, differing in membrane-binding properties which would be connected with their localization in the acrosome.

Acrosome↗
PubMed1983

Lead exposure and nerve conduction velocity: the differential time course of sensory and motor nerve effects.

Nerve conduction velocities (NCV) of the median motor, median sensory, peroneal motor, and sural nerves were measured on 40 lead-exposed automobile production workers as part of a comprehensive health survey. Blood lead (Pb-B) and blood zinc protoporphyrin (ZPP) were measured. The control group (N = 31) consisted of workers without lead exposure. All subjects were screened for the following conditions: Limb, neck or back injury, diabetes, neurological disease, and alcohol consumption of more than 28 alcoholic beverages per week. Limb temperature was assessed at three sites for each NCV measurement. The lead-exposed workers had slower median sensory NCV (42.9 vs. 46.8 m/sec, p less than 0.006) and slower sural NCV (37.8 vs. 42.8 m/sec, p less than 0.0004). All NCV estimates were then statistically adjusted for age and temperature, and transformed to Z values for further analyses. The mean standardized NCVs were slower in the lead-exposed group for the median sensory (-1.03 vs. -0.04, p less than 0.0003) and the sural nerves (-2.52 vs. -0.52, p less than 0.001). The study group was divided into two groups, with less than ten years and more than ten years of lead exposure. The subsample exposed less than ten years showed slowing of the median sensory (-0.94 vs. -0.04, p less than 0.005) and the sural nerves (-2.42 vs. -0.52, p less than 0.0001). Pb-B and ZPP levels were correlated with sural velocity (r = -0.54, p less than 0.04, and 4 = -49, p less than 0.06, respectively. Mean Pb-B was 59.7 micrograms/dl and mean ZPP was 175.8 micrograms/dl).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1982

Failure of serum ferritin levels to predict bone-marrow iron content after intravenous iron-dextran therapy.

The relation between serum ferritin levels and stainable-iron deposits in the liver, spleen, and bone marrow was investigated in 36 patients with chronic renal failure who died after being on haemodialysis for 1-103 months. Elemental iron (mean, 5450 mg) had been given intravenously as iron dextran to patients in a long-term subgroup, who had been on dialysis for more than 3 months. The results of semiquantitative histochemical assessment of tissue iron in slides obtained at necropsy (scale 0 to 4+) were confirmed by chemical analyses of tissue iron. Serum ferritin levels correlated well with the degree of hepatosplenic siderosis but did not always correlate with bone-marrow iron stores in these patients. Serum ferritin concentrations were raised in 10 marrow-iron-depleted subjects (mean, 1336 ng/dl). The paradoxical association of hepatosplenic siderosis with marrow iron depletion was observed in most of the patients on dialysis for less than 40 months. The histochemical data show that the bulk of intravenously injected iron dextran is taken up by the liver and spleen; that the hepatosplenic stores fail to be mobilised to the bone marrow; and that intravenous iron-dextran therapy, by-passing the intestinal mechanism for the regulation of iron absorption, carries a high risk of long-term hepatosplenic siderosis.

Aged↗
PubMed1982

Pleistocene Macaca from Hoxne, Suffolk, England.

Pleistocene macaque remains are uncommon in Great Britain. In addition to three specimens previously known from three sites, four teeth from Hoxne, Suffolk are recorded here. Closely resembling teeth of modern Macaca sylvanus (Barbary ape), they were recovered from a Middle Pleistocene stratum containing stone artifacts (including handaxes) and fauna including cold-climate lemmings.

Animals↗
PubMed1982

Vitamin A and beta-carotene content of seminal fluid and sperm of normospermic and oligozoospermic men.

Beta-carotene and vitamin A were estimated in 125 specimens of human seminal fluid and spermatozoa. In 72 of the specimens triiodothyronine, tetraiodothyronine, and T4-binding globulin were also determined. Vitamin A in seminal fluid increased from 10.4+/-l.8 microgram (SE) in severe oligozoospermia up to 19.1+/-2.5 microgram/100ml in specimens with high sperm densities. In spermatozoa, however, there was a trend for a decrease in vitamin content from 2.1+/-0.8 to 0.2 +/-0.07 microgram/108. In the majority of cases beta-carotene was undetectable and, when present, the levels were much lower than those of vitamin A. The amounts of triiodothyronine and tetraiodothyronine in seminal fluid were 0.19+/-0.03 ng/ml and 1.1+/-0.18 microgram/100ml, respectively. No correlation was found between levels of both hormones and quality of seminal fluid. T4-binding globulin was either very low or undetectable.

Alpha-Globulins↗
PubMed1982

Inhibition and enhancement of macrophage migration in the presence of lymphocytes and seminal fluid of men with fertility disorders.

Macrophage migration inhibition factor (MIF) towards autologous seminal fluid was studied in 29 infertile men, 16 of whom were also examined towards normal seminal fluid. In 10 patients, inhibition of macrophage migration was observed in the presence of 50 microgram of protein of autologous semen sonicates. Nine patients had enhanced macrophage migration in the presence of 5 microgram protein. Macrophage enhancement was more antigen dependent than the migration inhibition. In all patients seminal abnormalities were observed, being milder in the patients whose lymphocytes enhanced macrophage migration.

Humans↗
PubMed1982

Estimation of hyaluronidase activity of human semen and its relationship with sperm density by means of a simplified method.

Hyaluronidase activity was examined in 109 specimens of human semen of various sperm densities, seminal plasma, and spermatozoa sedimented by centrifugation. We used a modification of a method originally devised for estimation of hyaluronidase activity in Clostridia and which was bases on measurements of the area of hyaluronate digestion in agar plates. Enzyme activities in both semen and seminal plasma increased with increase in sperm density. The activity in seminal plasma, which appeared promptly after liquefaction and represented enzyme released from spermatozoa, ranged from 31% to 61% of the activity in semen. Activities of spermatozoa in sediments exhibited lower values than those calculated for sperm of whole semen, possibly due to leakage. Both activities, calculated per million sperm cells, gradually increased with decrease in sperm density. The possibility that with severe oligozoospermia the acrosome may become less prone to enzyme release or that the initial activity per cell may increase is discussed. These phenomena would represent additional characteristics of oligozoospermia.

Humans↗