Effects of meso-inositol deficiency on some important biological and chemical characteristics of yeast.
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In Vitro Techniques↗
Biomedical subjects
L M Lewin
Publications and source records attributed to L M Lewin.
Procarbazine effects on spermatogenesis in golden hamster: a flow cytometric evaluation.
The response of hamster testis to the administration of 450mg/kg procarbazine (PCB) over a period of 4 weeks was evaluated. Flow cytometry was used to investigate changes in cell populations in testicular single cell suspensions and to correlate these changes with those observed in histological sections. PCB caused significant decrease in testicular and epididymal weight and a drastic reduction in haploid cells and spermatogenic arrest, demonstrating variation among the test animals. The results obtained confirm previous observations concerning detrimental effects of PCB upon spermatogenesis in species such as the rat and mouse, though its effect on hamster testis is milder and does not include the germinal stem cells. The histological evaluation of the testis showed a good correlation with flow cytometric evaluation, emphasizing the usefulness of this method in providing quantitative and rapid results.
Animals↗
Role of free L-carnitine and acetyl-L-carnitine in post-gonadal maturation of mammalian spermatozoa.
Spermatozoa are produced in the testis and undergo post-gonadal modifications in the epididymis to acquire fertilizing ability. In epididymal plasma, high-molecular-weight proteins and such small molecules as free-L carnitine convert the gametes into "competent' and functional cells. This review summarizes the knowledge pertaining to L-carnitine and the significance of free L-carnitine uptake into the mature spermatozoa of mammals. We provide an overview of the function of free L-carnitine and carnitine esters in the metabolism of eukaryotic cells and review the role of the specific carnitine acyltransferases in mitochondrial transport of fatty acids and in modulating acyl-coenzyme A (CoA) pools in cellular organelles. In mammals, including man, free L-carnitine is taken from blood plasma and concentrated in the epididymal lumen. This epididymal secretion is beneficial for spermatozoa and is not merely an excretory waste. The uptake of free L-carnitine into the spermatozoa and its metabolic outcome are discussed first in in-vivo and then in in-vitro situations. Free L-carnitine goes through the sperm plasma membrane by passive diffusion. Free L-carnitine is acetylated in mature spermatozoa only. The excess acetyl-CoA from the mitochondria is probably stored as acetyl-L-carnitine and modulates the reserves of free CoA essential to the function of the tricarboxylic acid cycle. These properties of L-carnitine of buffering CoA in the mitochondrial matrix are known in somatic cells but are accentuated in this study of the male germinal cells. In the future, a precise measurement of the in-vivo and in-vitro concentrations of free CoA and acetyl-CoA in the cellular compartments of immature and mature spermatozoa might complete these data. The relationship between the endogenous pools of free and acetylated L-carnitine and the percentage of progressive sperm motility indicates a more important metabolic function related to flagellar movement. In conclusion, the potential to initiate sperm motility, which takes place in the epididymis, is probably independent of the carnitine system, while the energy properties of acetyl-L-carnitine can only be relevant in situations of "energy crisis'. The uptake of "cytoplasmic' free L-carnitine in mature spermatozoa must be a protective form of mitochondrial metabolism, useful to the survival of this isolated cell.
Acetylcarnitine↗
Myo-inositol clearance in renal failure and in patients with normal kidney function.
In order to determine the mechanism of elevated serum inositol in renal failure, the clearance values of inositol and of creatinine were measured in patients with normal kidney function and in those whose renal function was impaired due to varying causes. Mean serum inositol level in controls was 5.6 microgram/ml, and in patients with renal failure 28.6 microgram/ml. In control patients, inositol clearance was 2.8 ml/min, and tubular reabsorption of inositol was found to be over 97 percent. The inositol clearance of patients in renal failure varied from 0.62 to 17 ml/min. The ratio inositol clearance/creatinine clearance was elevated in uremic patients. Total amounts of inositol excreted in the urine of uremic patients were consistently higher than those excreted by control patients. The elevated serum inositol levels seen in renal failure were therefore not primarily caused by inability of the diseased kidney to excrete inositol.
Creatinine↗
Survey of carnitine content of human semen using a semiquantitative auxanographic method: decreased semen total carnitine concentration in patients with azoospermia or severe oligozoospermia.
A microbiological method, using the carnitine-requiring yeast, Torulopsis bovina ATCC 26014, was developed to identify samples of human semen which contained low levels (less than 250 micron M) of total carnitine. Of 399 semen samples from a male infertility clinic which were tested, 30 (7.5%) were low in carnitine. Of these, 14 were azoospermic and 16 were severely oligozoospermic. Some azoospermic samples (19 = 58%) and severely oligozoospermic samples (51 = 79%) did not give evidence of low carnitine concentrations. These results indicate that decreased total carnitine concentration in semen occurs in certain classes of azoospermic and severely oligozoospermic patients.
Biological Assay↗
Androgen-binding components of human semen.
Androgen-binding components were detected in human semen, using the dextran-coated charcoal method. Pre- and postvasectomy semen samples did not show significant differences in ability to bind dihydrotestosterone. Electrophoresis conducted in polyacrylamide gels in which tritiated dihydrotestosterone had been incorporated disclosed the presence of androgen-binding protein with properties characteristic of the ABP of Sertoli cell origin in ram semen but ABP was not detectable in human semen, even after concentrating it two or four fold. The binding of dihydrotestosterone was slightly greater in the later portion of split-ejaculate samples, but binding was found in the earlier fraction and in prostatic fluid, suggesting that androgen-binding components enter human semen with secretions of the prostate and seminal vesicle glands. It was concluded that the extent of androgen-binding by human seminal fluid is not a measure of Sertoli-cell function.
Adult↗
Investigations on the motility of human spermatozoa in a defined medium in the presence of metabolic inhibitors and of carnitine.
When washed human sperm were incubated in a modified Krebs-Ringer buffer solution in the absence of exogenous metabolizable substrates at 30 degrees C they maintained progressive motility for at least six hours. Under these conditions the spermatozoa apparently utilize endogenous substrates but addition of exogenous substrates (glucose, fructose, acetate, short-chain fatty acids, branched chain amino acids) did not affect the % progressive motility or % total motility of the cells. The phospholipase inhibitors, quinacrine and Upjohn No. 1002, inhibited progressive motility when added to sperm utilizing endogenous substrate, and subsequent addition of oxidative or glycolytic substrates did not reverse the inhibition. In contrast, the inhibition by KCN of progressive motility based upon utilization of endogenous substrate was reversed upon addition of glycolyzable compounds (glucose or fructose). The addition of carnitine or its acetyl-, propionyl-, isobutyryl-, valeryl- or isovaleryl esters did not consistently affect progressive or total motility of sperm samples. The inhibitor, octylsulfobetaine, inhibited sperm motility at a concentration higher than that required for inhibition of carnitine acetyltransferase or translocase activity. On the basis of these results it does not appear that exogenous carnitine has an effect on the motility of human sperm incubated under the conditions described here.
Carnitine↗
Antifertility effects of sulfapyridine on male hamsters.
Sulfapyridine was administered to mature male golden hamsters either by impregnation in feed pellets, or by subcutaneous injection as a solution in dimethylsulfoxide. The average litter size for control males was 8.3 +/- 3.3 (n = 13) vs. 4.2 +/- 2.7 (n = 11) for sulfapyridine-fed treated animals. Histology of the testis and epididymis was normal and sperm were normal in morphology and motility. Subcutaneous injection of sulfapyridine caused much more dramatic inhibition of male fertility than was achieved by feeding the drug. Sulfapyridine (750 mg/kg body weight in 0.2 ml DMSO) injected subcutaneously for 60 days was effective in reducing testis size and sperm quality. Histology of testes showed spermatogenic arrest at young spermatids. Two classes of animals were found in both sulfapyridine-fed and -injected treatment groups. One class was relatively resistant to the antifertility effects of the drugs. This difference may reflect differing abilities of the animals to convert sulfapyridine to an active form or to excrete its metabolites.
Animals↗
Loss of acid phosphatase from rat spermatozoa as a method for assessing the acrosome reaction.
A method is presented for evaluating the extent of the acrosome reaction by measuring the release of acrosomal acid phosphatase from rat spermatozoa during incubation under capacitating conditions. Treatment of spermatozoa with lysophosphatidylcholine or Triton X-100 released the acid phosphatase from the sperm cell. Using this enzymatic method we could not detect an alteration in enzyme activity following 5 h incubation under capacitating conditions. The effect of in vitro capacitation for 5 h in the absence or presence of heparin or ionophore A23187 was studied. Incubation in the presence of heparin (10 micrograms ml-1) caused a 32% increase in enzyme activity. After exposure of the spermatozoa to ionophore A23187 (0.5 microM) 16% increase of enzyme activity could be detected.
Acid Phosphatase↗
Changes during puberty in chromatin condensation, morphology and fertilizing ability of epididymal spermatozoa of the golden hamster.
Male golden hamster sperm acquire complete fertilizing ability at about 48 days of age. In this study hamsters, 27-130 days of age were killed and their male reproductive tracts examined. Sperm were found in the caudae epididymides from 37 days onward. None of the sperm from animals younger than 41 days were capable of fertilizing ova when placed in the uteri of superovulated females. Using flow cytometry of acridine-orange-stained cells, the chromatin condensation in cauda epididymal sperm was investigated. It was seen that DNA from sperm from the younger animals (under 40 days of age) was less tightly bound to protamine than that obtained from mature animals. In summary, the earliest sperm produced by pubertal hamsters were immature with regard to chromatin condensation, morphology, motility, and ability to fertilize ova, and they developed mature characteristics in the period between 40-48 days of age.
Aging↗