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Biomedical subjects

R M Levin

Publications and source records attributed to R M Levin.

At least 307 records · Page 17Linked to original sources
PubMed1981

Clinical use of the turbidimetric analysis of sperm motility: comparison with visual techniques.

Semen characteristics of men with apparent fertility problems are analyzed primarily by routine visual techniques. Although these techniques provide quantitative information regarding the sperm count, they give only qualitative information about sperm motility. We compared visual microscopic ratings of sperm motility (based on an arbitrary scale of 0 to 4 in half-unit steps) with turbidimetric spectrophotometric analyses for 100 patients from our male fertility clinic. In the turbidimetric method, semen is layered on the bottom of the cuvette filled with Lopata's medium, and motility is quantitated as the rate of change in optical density as the sperm swim upward into the light path. The visual sperm motility rating did not correlate with the turbidimetric rating. Whereas most of the patients had visual ratings of 2.5 to 3.0 (indicating normal motility), the majority had turbidimetric motility factors that were well below the average motility factor for a control group. On the basis of these studies we believe that the turbidimetric analysis of sperm motility is a much more accurate measure of sperm motility than is visual microscopic analysis. Its major advantages are that (1) it provides a quantitative measure of sperm motility; (2) it does not rely on arbitrary rating by an individual; and (3) the sperm must perform work in order to be measured (i.e., leave the semen and swim upward into the light path).

Cell Survival↗
PubMed1981

Quantitative analysis of the effects of caffeine on sperm motility and cyclic adenosine 3',5'-monophosphate (AMP) phosphodiesterase.

Caffeine in high concentrations (2 to 6 mM) has been shown to increase sperm motility and metabolism when added to semen. High concentrations of caffeine have also been demonstrated to inhibit cyclic adenosine 3',5'-monophosphate (AMP) phosphodiesterase isolated from sperm. Since cyclic AMP is known to increase sperm motility, some investigators have attributed the stimulatory effect of caffeine on sperm motility to the inhibition of phosphodiesterase. The authors used semen from healthy donors to quantitate the effects of caffeine on sperm motility by turbidimetric analysis and to analyze kinetically the effect of caffeine on phosphodiesterase isolated from sperm preparations. Caffeine (0.012 to 2.0 mM) produced a dose-dependent increase in sperm motility. The ED50 for motility stimulation was 300 microM of caffeine; a significant increase in motility was observed with 60 microM; and maximal stimulation (a threefold increase) occurred with 1 mM. The phosphodiesterase activity of sperm homogenates displayed linear kinetics with a Vmax of 0.5 nmoles/mg of protein per minute and a Km of 125 microM. Caffeine (0.1 to 40 mM) produced a dose-dependent inhibition of sperm phosphodiesterase. Kinetically, caffeine was a mixed inhibitor of sperm phosphodiesterase, displaying a Ki of 1.2 mM. These results suggest that caffeine may stimulate sperm motility by a mechanism other than phosphodiesterase inhibition.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1981

Bladder transection--a functional, neurophysiological, neuropharmacological and neuroanatomical study.

Experimental models to represent the surgical methods of bladder transection in humans were performed on dogs and rabbits. The effects on vesical neurophysiology were studied by cystometry with bethanechol supersensitivity testing; by in vitro pharmacological responsiveness; by determination of autonomic receptor densities using radioligand binding and by autonomic neurohistochemical staining. Analysis revealed that transection with or without neurovascular preservation resulted in an alpha-adrenergic denervation and cholinergic decentralisation. A comparison with the surgical models is presented and proposed mechanisms of action are discussed in relation to the experimental results.

Animals↗
PubMed1981

Effects of psychotropic drugs on human sperm motility.

Imipramine has been shown to have a potent inhibitory effect on sperm motility in vitro. Because of the frequent chronic use of antidepressants in treatment of depression, we investigated the in vivo effects of desmethylimipramine and lithium carbonate on sperm function in patients suffering from clinical depression. We also studied the in vitro effects of a series of neurotrophic agents on sperm motility. There were no significant differences in sperm count, viability, or motility between a group of patients diagnosed as having clinical depression and a group of semen donors with normal sperm characteristics. Three weeks of continuous therapy with desmethylimipramine or lithium carbonate resulted in a significant decrease in sperm viability but no significant change in sperm count or motility. The in vitro drug studies demonstrated that imipramine hydrochloride, desmethylimipramine, chlorpromazine, trifluoperazine, and nortriptyline hydrochloride were all potent inhibitors of sperm motility, whereas lithium carbonate had no effect on motility.

Adult↗
PubMed1981

The ontogeny of the autonomic innervation and contractile response of the rabbit urinary bladder.

Although there has been considerable research on urinary bladder innervation, physiology and response to pharmacological agent, very little information is available concerning the ontogeny of bladder innervation and the contractile response to autonomic agents. The developmental aspects of urinary bladder innervation and function have been studied in the rabbit utilizing the following techniques: histochemical methodology to demonstrate autonomic innervation; in vitro responses to autonomic agents to demonstrate contractile responses; and ratio-ligand binding assays to determine specific receptor densities. The results of these studies can be summarized as follows: 1) at birth, the density of adrenergic fibers in the rabbit urinary bladder is very sparse, whereas there is a dense cholinergic innervation present. Over the first 6 weeks of postnatal development, there is a rapid progressive increase in the density of adrenergic fibers, whereas there is no significant change in the cholinergic innervation; 2) at birth, isolated strips of bladder respond poorly to methoxamine (alpha adrenergic agonist) and isoproterenol (beta-adrenergic agonist), but well to bethanechol (muscarinic cholinergic) and ATP (purinergic); 3) at birth, the density of adrenergic alpha and beta receptors is low; over the first 6 weeks of postnatal development, the density increases progressively to adult levels. The muscarinic receptor density is high at birth and does not change significantly over the first 6 weeks of postnatal development.

Animals↗
PubMed1980

A quantitative method for determining the effects of drugs on spermatozoal motility.

The purpose of this study was to demonstrate whether the turbidimetric method of measuring sperm motility could be used to quantitate the effects of drugs. Human ejaculate was layered on the bottom of a cuvette containing Lopata's medium, and sperm motility was measured spectrophotometrically. The slope of the initial increase in absorbance (OD) is directly proportional to the rate at which the fastest fraction of sperm enters the light path and provides a highly reproducible measure of sperm motility. The effects of caffeine and imipramine on sperm motility were studied. The test drug was added to the buffer before the semen was introduced so that the assay would measure the immediate effect of the drug on the sperm. Caffeine produced a dose-dependent increase in sperm motility, and imipramine produced a dose-dependent decrease. We conclude from these studies that the turbidimetric assay is capable of providing a rapid, reproducible, quantitative analysis of the effects of drugs on sperm motility.

Caffeine↗
PubMed1980

Cholinergic, adrenergic and purinergic response of sequential strips of rabbit urinary bladder.

In this study, we have characterized the response of five sequential segments of urinary bladder to cholinergic, adrenergic, and purinergic agonists. The results indicate that an abrupt alteration in pharmacological response between bladder body and base occurs at the level of the ureteral orifices. The bladder body responds preferentially to urecholine (muscarinic cholinergic), isoproterenol (beta adrenergic) and ATP (purinergic), whereas the bladder base responds perferentially to methoxamine alpha adrenergic). In parallel studies, the density of both muscarinic cholinergic receptors ([3H]quinuclidinyl benzilate binding sites) and beta adrenergic receptors were significantly higher in the body than in the base, whereas the concentration of alpha adrenergic receptors was greater in the bladder base than in the body. From these studies, we conclude that the differences in the response of the bladder base and body to cholinergic and adrenergic agents are primarily due to differences in the densities of the specific autonomic receptors. In addition, the response of the bladder to ATP (which is a putative neurotransmitter in the urinary bladder) can also be separated between body and base. The distribution is similar to that observed for urecholine.

Adenosine Triphosphate↗
PubMed1980

Adrenergic alpha receptors outnumber beta receptors in human penile corpus cavernosum.

Using specific adrenergic receptor binding assays, we characterized both alpha and beta adrenergic receptors in human penile corpus cavernosum tissue. The density of alpha adrenergic receptors in corporal tissue was found to be almost ten times greater than the density of beta adrenergic receptors. Our results are compatible with studies that suggest an important role for adrenergic innervation in penile erection.

Humans↗
PubMed1980

Estrogen-induced alterations in the autonomic responses of the rabbit urinary bladder.

The effect of estrogen administration on the autonomic innervation of the rabbit urinary bladder was studied. Immature female white rabbits were injected twice daily with estrogen (150 microgram/kg) for 4 consecutive days. Control animals received injections of vehicle. The response of bladder strips to the following agonists were determined for control and estrogen-treated animals: methoxamine (alpha adrenergic); isoproterenol (beta adrenergic); bethanechol (muscarinic cholinergic); ATP (purinergic); and potassium chloride (nonreceptor mediated). Additionally, the adrenergic and cholinergic receptor densities were determined by standard radioligand binding techniques. Estrogen induced a marked increase in the response to alpha adrenergic, muscarinic cholinergic and purinergic agonists in the bladder body and midbladder. No significant alterations were noted in the bladder base. In addition, no alterations were noted for isoproterenol or potassium chloride. The receptor densities paralleled closely the physiological responses. Estrogen induced a significant increase in alpha adrenergic and muscarinic receptors in the bladder body and midsection, whereas no change was noted in the receptor density of the bladder base. Estrogen did not alter the beta receptor density. These findings indicate that the urinary bladder responds as a target organ for estrogen-induced alterations in autonomic innervation.

Animals↗
PubMed1979

A practical approach for the evaluation of women with abnormal polytomography or elevated prolactin levels.

Based upon the experience gained in the evaluation of 60 patients with abnormal polytomography and/or elevated prolactin levels, the following observations can be made: Patients with amenorrhea, amenorrhea and galactorrhea, galactorrhea alone, or anovulatory cycles and infertility may or may not have pituitary tumors. Clinical symptoms do not always correlate with the prolactin level, and patients with normal prolactins may have pituitary tumors. The incidence of empty sella is significant (15.8% in this series). Visual field examination is not a useful screening procedure, but evaluation of thyroid function is important to detect the occasional patient with hypothyroidism (3.5% in this series). The insulin tolerance test is not helpful in detecting the presence of pituitary tumors or in guiding management decisions, and the CT scan contributes little and should be omitted from the evaluation process. A straightforward, economical, and efficient approach to this clinical problem is presented.

Adenoma↗
PubMed1979

Quantitative analysis of alpha and beta adrenergic receptor densities in the lower urinary tract of the dog and the rabbit.

Using specific radioligand receptor binding assays, we have, for the first time, quantitated both alpha- and beta-adrenergic receptors in the musculature of the lower ureter, bladder body, posterior bladder base, and proximal urethra of the dog, and in the bladder base and body of the rabbit. For the beta receptor assay 3H-dihydroalprenolol was used as the ligand, and, for the alpha receptor assay, 3H-dihydroergocryptine was used. In the dog, there was a significantly greater density of beta receptors in the bladder body than in either the ureter or the posterior bladder base. The urethra had an intermediate density. The bladder base and the proximal urethra had a significantly greater density of alpha receptors than either the ureter or the bladder dome. The dissociation constant of beta receptors for DHA was approximately 9 nM for all tissues studied, and that of alpha receptors for DHE approximately 7 nM. A similar distribution of alpha-and beta adrenergic receptors was seen in the rabbit bladder.

Alprenolol↗