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Biomedical subjects

H Levinsky

Publications and source records attributed to H Levinsky.

At least 37 records · Page 2Linked to original sources
PubMed1988

Sialic acid in platelets of schizophrenic patients.

1. Nerve cell membrane sialic acid is involved in the activity of nervous tissue by its capacity to bind Ca ions and positively charged biogenic amines. 2. Blood platelets may serve as a model for amine-storing neurons. 3. The purpose of the present study was to determine the sialic acid content of platelets of schizophrenic patients in view of reports showing a reduced serotonin uptake by their platelets. 4. To this end platelets were isolated from the blood of 26 schizophrenic patients (13 males and 13 females) of various diagnostic subtypes and from 21 healthy subjects, and sialic acid was determined after hydrolysis at 80 degrees for 1 h in 0.1 NHCl. 5. The results showed significantly lower contents of sialic acid in the patients as compared to controls calculated both per 10(8) cells and per mg protein (18% and 25% lower, respectively) and appear to be in line with the reduced serotonin uptake in their cells in schizophrenia. 6. There were no appreciable differences between sexes and between the various subtypes of this disease.

Adult↗
PubMed1988

Sialic acid and neuraminidase activity in rat kidneys 6 months after uninephrectomy.

Sialic acid and neuraminidase activity were determined in the cortex of the remnant kidneys of six uninephrectomized rats. As controls served either the kidneys removed at operation or age-matched kidneys from eight sham operated rats. Six months after uninephrectomy the kidneys became hypertrophied and their mean weight was about 40% higher than age-matched kidneys. Blood urea and creatinine and protein levels in 24-hr urine collections were significantly higher in the experimental animals as compared to those of the same animals before nephrectomy and to sham operated rats, indicating a marked impairment of kidney function. The mean concentration of sialic acid in the cortex of hypertrophied kidneys was not statistically different from either that of the removed or that of the age-matched kidneys. Neuraminidase activity expressed as either per gram fresh tissue or per milligram protein, was not different in the removed and in the hypertrophied kidney. The activity, however, in the latter was significantly lower than in the age-matched kidneys. Whether this finding can be associated with the impairment of kidney function in rats 6 months after uninephrectomy remains to be studied.

Animals↗
PubMed1988

Sialic acid content and sialyltransferase activity in lymphocytes from neonates.

Venous blood from 24 healthy volunteers, 20-40 years old, and umbilical cord blood from 28 healthy full-term neonates, immediately after delivery, was used for the determination of lymphocyte sialic acid content and sialyltransferase activity. A significantly increased content of lymphocyte sialic acid and an increased sialyltransferase activity were observed in neonates as compared to adults. It is suggested that the increased sialic acid content of fetal lymphocytes may contribute to a possible masking effect of antigenic sites on fetal immunocompetent cells.

Adult↗
PubMed1988

Sialyl transferase in human semen.

The activity of the enzyme sialyl transferase, which is responsible for the transfer of sialic acid, has been examined in the following human seminal plasma: (1) originating from semen with sperm counts above 30 X 10(6)/ml and exhibiting normal values of other andrological parameters; (2) from semen with sperm counts below 25 X 10(6)/ml and with other andrological parameters of poor quality; (3) from semen devoid of sperm. Additionally, enzyme activity was examined in fractionated (split) semen. The activity in plasma based on measurement of radioactivity incorporated into asialofetuin, following incubation in the presence of 14C sialic acid, was expressed as cpm both per volume and per mg protein. There was a tendency for decreased activity with the decrease in sperm density of semen. The difference, however, lacked statistical significance. Enzyme activity in split semen was significantly lower in the first than in the second fraction.

Humans↗
PubMed1987

Modulation of carcinoembryonic antigen release by HT-29 colon carcinoma line in the presence of different agents.

In this study we followed the effects of various differentiating agents on the expression of carcinoembryonic antigen (CEA) released into the medium by a colon carcinoma cell line HT-29. Butyric acid 1 mM markedly increased the level of CEA (12-fold in comparison to control levels). 12-O-tetradecanoyl-phorbol-13-acetate (TPA) 50 ng/ml and 5-azacytidine 4 x 10(-6) M increased the amount of CEA, 2- and 1.5-fold respectively. On the other hand retinoic acid 10(-5) M, N methyl-formamide 1% and N,N hexamethylene bisacetamide 2.5 mM decreased CEA 2-, 4- and 3-fold respectively. Our results emphasize that various differentiating agents affect CEA levels differently. Thus changes in CEA levels appear not to be reliable as a marker of a more differentiated phenotype.

Acetamides↗
PubMed1986

Lactate dehydrogenase and alkaline phosphatase isoenzymes and protein-bound sialic acid in regenerating rat liver.

Lactate dehydrogenase (LDH) and alkaline phosphatase (AP) isoenzyme patterns and protein-bound sialic acid content were compared between normal, regenerating rat liver 10 days after partial hepatectomy and fetal rat liver. For this purpose, liver from ten adult rats and two pools of ten fetal livers each were examined. Isoenzymes were separated by electrophoresis on cellulose acetate and their percent distribution calculated after quantitation by densitometry of the bands. LDH-5 and LDH-4 combined represented in all the tissues examined 90%-94% of the total activity. LDH-5/LDH-4 ratios were nearly equivalent in the normal and regenerated liver (7.14, 6.41), but substantially lower in fetal liver (2.50). Two bands of AP were visualized in electropherograms. AP-1/AP-2 ratio was lower in regenerated liver (1.57) as compared to normal liver (2.27) and still lower in fetal liver (1.06). Protein-bound sialic acid was, on protein basis, slightly but not significantly higher in regenerated liver (1.71 microgram/mg protein) than in normal liver (1.43), and significantly higher in fetal liver (1.87). The relatively small differences in isoenzyme patterns and in protein-bound sialic acid between regenerated and normal liver as compared to those between fetal and normal tissue add support to the view that the cells in regenerated liver are not of embryonic origin.

Alkaline Phosphatase↗
PubMed1985

Sialic acid content of erythrocytes in uremic patients. Correlation with the age distribution of erythrocytes as assessed by glutamic oxaloacetic transaminase determination.

In a previous study we suggested that an enrichment in young red blood cells (RBC) should occur in the erythrocyte population of uremic-anemic patients. This change in RBC age distribution together with the fact that young cells were reported to be richer in sialic acid would provide an explanation for the observed lack of difference in sialic acid content between patients' and controls' whole erythrocyte populations in spite of an increased neuraminidase activity found to be present in patients' serum. To verify this assumption glutamic oxaloacetic transaminase (GOT) activity, which is an erythrocyte age index, and sialic acid were determined in low and high density fractions separated by centrifugation of packed cells representing young and old RBC, respectively, from two groups of 8 individuals with chronic renal failure and two groups of controls. GOT was determined also in whole erythrocyte populations. Mean GOT activity was significantly higher in the young fractions compared to the old of both patients' and control RBC (14.9 vs. 7.8 and 12.4 vs. 7.5 IU/g Hb). Activity of the whole RBC population was significantly higher in uremics as compared to controls (11.7 vs. 5.6 IU/g Hb) which is compatible with a lower median erythrocyte age. Mean sialic acid was higher in the young fractions as compared to the old (42.7 vs. 35.3 nmol/10(9) cells in controls and 48.9 vs. 43.0 nmol/10(9) cells in patients). These differences together with an enrichment in young cells would compensate for the eventual loss of sialic acid in the whole population resulting from an increased neuraminidase-like activity in patients' serum.

Aspartate Aminotransferases↗
PubMed1985

Sialic acid in newborn and maternal lymphocytes: preterm deliveries.

Sialic acid was determined in newborn and maternal lymphocytes immediately after preterm deliveries of 34 and 35 weeks of gestation. The results were compared with those found in full-term deliveries. In contrast with full-term deliveries, in preterm deliveries a significant increase in sialic acid in maternal as compared to newborn lymphocytes was found. However, the mean cumulative value of sialic acid for maternal and newborn lymphocytes was similar in both groups. In addition to this, sialic acid concentrations seem to be sex-dependent and higher mean cumulative values for maternal and newborn lymphocytes could be found for male as compared to female newborns after full- as well as after preterm deliveries.

Female↗
PubMed1985

Lack of correlation between human y-positive spermatozoa and acrosomal abnormalities and variations in intensity of fluorescence of sperm stained with quinacrine compounds.

Seminal fluid from 170 men was examined for acrosomal abnormalities of sperm (Papanicolaou procedure X 1000) and for y-positive cells (quinacrine-stained smears). No correlation was found between these parameters, suggesting that acrosomal abnormalities are similarly distributed among x- and y-bearing spermatozoa. The proportion of y-positive sperm was found to be low (23.6 + 10.7% (SD) for the oligozoospermic specimens and 23.7 +/- 9.8% for specimens with sperm counts above 40 million/ml). Three degrees of fluorescence intensity were observed--weak, moderate, and strong--the strong fluorescence being associated with the highest percentage of y-bodies (30.6 +/- 12.7%, 36.6 +/- 5.7%) and the weak fluorescence with the lowest (16.7 +/- 7.0%, 15.0 +/- 9.5%). It is suggested that structural abnormalities and/or metabolic alterations in either the DNA molecule or the chromosomal proteins may be responsible for variability in the ability to bind quinacrine compounds.

Acrosome↗
PubMed1985

Deoxyribonuclease activity in human sperm.

A previous failure to detect DNase activity in human sperm sonicates was ascribed to an inadequate amount of sperm used. In the present work aliquots contained more sperm (1.5-2.5/10(6)), permitting the detection of enzyme activity. The latter was significantly higher in spermatozoa of oligozoospermic origin compared with activity in normospermic specimens.

Deoxyribonucleases↗
PubMed1984

Neuraminidase-like activity in sera of uremic anemic patients.

A shortened life of erythrocytes in uremia has been suggested as one of the causes of anemia in this condition. Since partially desialylated erythrocytes are promptly removed from the circulation, we examined whether sera from renal failure patients would exhibit increased neuraminidase activity which could be held responsible for this phenomenon. Sera of 22 patients with end stage renal failure were examined for neuraminidase activity by assessing their effect on desialylation upon incubation at 37 degrees C for 2 and 1 h, respectively, of erythrocytes of healthy donors matched for blood group and of fetuin as substrate. As deduced from the residual content of sialic acid of erythrocytes and of the amount of sialic acid released from fetuin, the results showed a statistically higher neuraminidase-like activity of patients' sera as compared to sera of healthy individuals. It is suggested that increase in neuraminidase activity could be one of the factors involved in the mechanism of generation of anemia in uremia by acting on erythrocytes, rendering them more prone to sequestration by the liver and spleen.

Adult↗
PubMed1983

Effect of diclofenac-sodium (Voltaren) on the electrical charge of human platelet membrane.

Platelets incubated with prostaglandin synthetase inhibitors, i.e. aspirin (ASA) and diclofenac-sodium (Voltaren) show a decreased capability to aggregate. While ASA induces the complete loss of platelet pseudopodia, Voltaren causes the appearance of long, needle-shaped pseudopodia, a finding which may suggest a rather increased tendency to aggregate. Platelets labeled with ferritin hydrazide and examined with a transmission electron microscope and by X-ray analysis show a greater deposition of ferritin hydrazide after incubation with Voltaren in comparison to those incubated with ASA and to the controls. This finding suggests an increased negative charge of the stretched platelet membrane after incubation with Voltaren with a subsequent increase in the repulsive forces between platelets.

Aspirin↗
PubMed1983

Sialic acid in lymphocytes and sera from mothers and their newborns after normal deliveries.

Sialic acid was determined in newborn and maternal lymphocytes as well as in newborn and maternal serum immediately after normal deliveries. A significant increase in sialic acid in newborn as compared to maternal lymphocytes was found. Sialic acid concentration seems to be sex-dependent for newborn lymphocytes only, and higher concentrations of sialic acid were observed in male as compared to female newborn lymphocytes. No differences between the sialic acid concentration in maternal and control lymphocytes could be found. In newborn serum, sialic acid was significantly reduced as compared to maternal or control serum. No sex-linked differences were observed. No differences between the concentration of maternal and control serum were detected.

Female↗
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↗