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Biomedical subjects

K Purvis

Publications and source records attributed to K Purvis.

At least 55 records · Page 3Linked to original sources
PubMed1989

[Smoking and sperm quality in men undergoing fertility studies].

The sperm quality (sperm number, concentration, motility, morphology and vitality) of 350 men under fertility investigation were compared in relation to their smoking habits. No significant differences (Kruskal-Wallis test) in sperm quality could be demonstrated between non-smokers, moderate smokers (1-14 cigarettes/day) and heavy smokers (15-40 cigarettes/day). This was true when all the data were analyzed together and when analyzed separately for oligospermic/hypospermic men (1-39) or for men with reduced forward motility (less than 25% of sperm cells with progressive movement). The distribution of non-smokers, moderate and heavy smokers was the same in groups of men with normal sperm quality as in groups with reduced quality. The present study does not provide support for the contention that smoking has deleterious effects on sperm quality, at least when using conventional parameters.

Adult↗
PubMed1989

Correlates of human sperm motility assessed by laser Doppler spectroscopy.

The sperm motility characteristics of 140 men (percentage motile and average velocity of all sperm in motion; percentage progressive and the average velocity of sperm swimming more than 15 microns/sec) were determined using a laser-Doppler technique and correlated with other aspects of sperm quality, including the concentration and the proportion of abnormal and dead sperm in the ejaculate. In addition, the influence of the length of the period of abstinence, the viscosity of seminal plasma and the volume of the ejaculate were also assessed. The four motility characteristics were all highly correlated with each other. The magnitude of all four parameters increased in an exponential fashion with increasing sperm number up to 400 x 10(6) per ejaculate. At higher numbers, no further improvement in motility was observed. Moreover, increasing sperm number was associated with a decline in the proportion of sperm exhibiting abnormalities in morphology but with an increase in viable sperm 30 min after ejaculation. The relative viscosity of the ejaculates had generally no influence on sperm motility. In contrast, certain of the sperm motility characteristics, including the average velocity, were significantly negatively correlated with the length of the abstinence period.

Adult↗
PubMed1989

Stability of sperm characteristics in men with disturbances in sperm quality.

Sixty-one men referred to our laboratory for semen analysis, and subsequently judged to exhibit some form of sperm pathology, were asked to return for a second analysis, not less than 2 months after the first, in order to assess the stability of the pathological changes observed. In almost half of the cases, the referring physician had, on his own initiative, started hormone or antibiotic treatment. The sperm parameters studied included sperm count, sperm motility judged by laser-Doppler spectroscopy, and sperm morphology and viability. The motility characteristics included percentage motile, their average velocity, and percentage swimming in a progressive manner, and their progressive velocity. In untreated subjects, there was no significant difference between the first and second analysis in any of the sperm parameters measured. This was also true for both oligozoospermic individuals (less than 20 x 10(6) sperm/ml) and the group with higher sperm concentrations. All parameters were highly correlated on the two occasions. The average coefficients of variation of the paired observations were highest for sperm count (approximately 25%) and lowest for sperm velocities and the proportion of abnormal and viable cells in the ejaculate (1-9%). No major differences in the extent of variation could be detected between the low and high sperm density groups. In general, the unsystematic antibiotic and hormone regimens (clomiphene or androgen) used by the referring physicians had no discernable effect on any aspect of sperm quality, indicating the need for more controlled and standardized programmes of treatment.

Adult↗
PubMed1989

Cigarette smoking and human sperm quality assessed by laser-Doppler spectroscopy and DNA flow cytometry.

The sperm qualities of 350 men under fertility investigation were compared in relation to their smoking habits. The sperm variables included number, motility, morphology and vitality. Sperm motility was assessed objectively by laser-Doppler spectroscopy. In a randomly selected group, sperm samples were subjected to flow cytometry to assess the levels of DNA condensation. No significant differences (Kruskal-Wallis' test) in any aspect of sperm quality including DNA distribution could be demonstrated between non-smokers, moderate smokers (1-14 cigarettes/day) and heavy smokers (15-40 cigarettes/day). This was true when the data were pooled and when oligozoospermic/hypozoospermic ejaculates (1-39 x 10(6)/ml) and asthenozoospermic ejaculates (less than 25% of sperm cells with progressive movement) were analysed separately. The distribution of non-smokers, moderate and heavy smokers was the same in groups of men with normal sperm quality as those with impaired quality. The present study does not provide support for the contention that smoking has deleterious effects on sperm quality, at least using conventional parameters.

DNA↗
PubMed1989

Polyamines and other accessory sex gland secretions in human seminal plasma 8 years after vasectomy.

In 56 males, vasectomized 8 years previously, and in 56 age-matched non-vasectomized controls, a number of secretory products of prostatic, seminal vesicular and epididymal/testicular origin were used to monitor post-operative changes in accessory sex gland function. Significant reductions were observed in seminal plasma volume (3.0 vs 4.9 ml, P less than 0.01), and the total ejaculate contents of zinc (5.1 vs 9.7 mumol, P less than 0.01), magnesium (10.6 vs 26.5 mumol, P less than 0.01), PAP (371 vs 1260 IU, P less than 0.005) and citric acid (76.7 vs 127.9 mumol, P less than 0.05), indicating a major impact on secretions of prostatic origin. Unaltered PGE-1 (54.3 vs 53.2 micrograms, P less than 0.95) and fructose (3.9 vs 4.5 mumol, P greater than 0.1) indicated no effects on the secretory function of the seminal vesicles. A marked reduction was demonstrated in the ejaculatory contents of the polyamines, spermidine (366 vs 650 nmol, P less than 0.005) and spermine (5435 vs 11 804 nmol, P less than 0.05) but not their acknowledged precursor, putrescine, which is also of prostatic origin.

Acid Phosphatase↗
PubMed1988

Distribution of Thyroliberin (TRH)- and 12-O-tetradecanoylphorbol 13-acetate (TPA)-activated adenylyl cyclase in normal and neoplastic tissue with special reference to the prostate.

Tissue specificity of the Thyroliberin (TRH)- and 12-O-tetradecanoylphorbol 13-acetate (TPA)-sensitive adenylyl cyclase has been studied using normal or neoplastic organ samples or cells from the pituitary gland, stomach, prostate, myocardium, liver and bone. It appeared that TRH stimulates the adenylyl cyclase in both normal (basal cells), hyperplastic and adenocarcinomatous prostate as well as in the pituitary and stomach. TPA also stimulated the enzyme from the prostate and other organs/cells, but to a greater extent in neoplastic tissue. Functional links from protein kinase C to adenylyl cyclase and from protein kinase C to tyrosine kinase/oncogene expression have been established. Hence it is believed that TRH, which stimulates the adenylyl cyclase and protein kinase C in the pituitary, may serve as a factor contributing to transformation of prostatic cells or enhanced cell proliferation in prostatic cancer.

Adenylyl Cyclases↗
PubMed1988

Isolation by using albumin columns of a cohort of fast-swimming human spermatozoa.

Unwashed human spermatozoa enter columns of 20% albumin in cohorts and not in a continuous stream. Using normospermic ejaculates, a single cohort, representing approximately 10% of the total number of spermatozoa added, appeared within 1 h of addition. In contrast, when ejaculates from asthenozoospermic men were tested using the same incubation period (1 h), the cohorts contained less than 5% of the total. Exposure of ejaculates to 2-deoxyadenosine, a potent stimulator of sperm motility, doubled the number of spermatozoa present in the cohort, but not the average velocity of the group. We suggest that spermatozoa also enter the cervical mucus and pass through the female reproductive tract in cohesive groups.

Cell Separation↗
PubMed1988

Hormonal control of prostate function.

The intention of this article is to provide an introduction to some of the recent concepts within the subject of hormonal regulation of the prostate gland.

Androgens↗
PubMed1987

Prolactin selectively stimulates ornithine decarboxylase in the lateral lobe of the rat prostate.

In androgenized-hypophysectomized rats, ovine prolactin stimulated the activity of the ornithine decarboxylase (ODC) of the lateral lobes, but not the ventral and dorsal lobes of the prostate glands in a time- and dose-dependent fashion. High degrees of enzyme stimulation were associated with significant elevations in the endogenous levels of its product, putrescine. The relative response to prolactin over basal activities was relatively unaffected by indomethacin but decreased with cycloheximide, suggesting that prostaglandins do not mediate the effects of the hormone, but that a high rate of protein synthesis is a prerequisite for its expression. Indomethacin alone significantly increased the basal activity of the enzyme above control levels, suggesting that prostaglandins may normally exert a degree of inhibition on the ODC. The selective activation of the lateral lobe ODC supports previous reports of a differential response of the various prostatic lobes to prolactin, and also provides a convenient biochemical response for examining details of prolactin action on this organ.

Androgens↗
PubMed1987

Independent control of citrate production and ornithine decarboxylase by prolactin in the lateral lobe of the rat prostate.

Prolactin stimulated the citric acid content of the lateral lobe of the prostate of androgenized-hypophysectomized rats in a time-dependent manner. This stimulation of citric acid levels was not blocked by pretreatment of the animals with the ornithine decarboxylase (ODC) inhibitor, alpha-difluoromethyl ornithine (DFMO), suggesting that the prolactin induction of citric acid in this organ is not mediated through activation of the ODC. The efficacy of the dose of inhibitor used was monitored by analysis of the diamine product of ODC, putrescine. Further evidence of an independent control of citric acid and polyamine synthesis in the lateral lobe was provided by their differing age distributions in intact animals. ODC activity decreased sharply with age, whereas the tissue concentrations of citric acid remained relatively constant. Both studies suggest that although citric acid and ODC are modulated by prolactin, their synthesis or activation are controlled independently of each other.

Aging↗
PubMed1987

Further observations on the autoregulation of the prolactin receptor in rat ventral prostate explants.

In confirmation and extension of an earlier preliminary communication, ovine prolactin was found to elevate prolactin binding by approximately 100% in rat ventral prostate explants incubated for 20 h in vitro. A stimulation was observed with low doses of ovine hormone (150 micrograms/l) which, from available data on the relative biological potencies, could be considered equivalent to the upper limit of the physiological range of endogenous rat prolactin. The response was associated with a lag period of 3-6 h. The effect could be obtained with other lactogenic hormones, including human and rat prolactin and human growth hormone, but not with non-lactogenic hormones such as insulin, hCG, corticosterone, testosterone or oestradiol. The prostaglandin synthesis inhibitor, indomethacin, and the Ca2+-antagonist, verapamil, could not counteract the increase in prolactin binding induced by prolactin treatment, nor could dibutyryl cyclic AMP alone mimic the response. These data suggest that prostaglandins, Ca2+ or cAMP do not mediate the alteration in receptor binding. Furthermore, inhibition of lysosome activity by chloroquine could not alone increase the prolactin binding in the control tissues, suggesting that up-regulation does not simply reflect a protective action of prolactin on receptor degradation.

Animals↗
PubMed1987

Thyrotrophin-releasing hormone in human ejaculate.

Immunoassayable TRH in human ejaculate was eluted from a gel column in a form with a molecular weight larger than that of the native peptide. With reverse-phase high-performance liquid chromatography (HPLC) the same activity co-eluted with standard TRH. Incubation of ejaculates at room temperature for 8 h was associated with a time-related increase in the total immunoassayable TRH. Analysis by HPLC of ejaculates after 12 h of incubation at room temperature indicated that, whereas the levels of the peptide co-eluting with native TRH declined with time, there was a concomitant increase in the concentration of a molecular species which also cross-reacted with the TRH antiserum, but which was more hydrophobic. The latter species is presumably identical to the tetrapeptide recently described by others and which may arise from the proteolytic degradation of secretory macromolecules. Although immunological activity was present in all six fractions of split ejaculates, the bulk of the peptide was associated with the later portions, implying a major vesicular contribution. However, secretions isolated from surgical preparations of the seminal vesicles contained undetectable levels of peptide, suggesting that the ejaculation process may represent a stimulus for its appearance in the semen. This study is further support for a local involvement of TRH in male reproductive function.

Chromatography, Gel↗
PubMed1986

Hormonal activation of the adenylyl cyclases of the rat and human prostate gland.

The rat ventral prostate and the human hyperplastic prostate contain adenylyl cyclases which can be activated by a variety of neurotransmittors, including vasoactive intestinal peptide (VIP), beta 2 adrenergic agonists, and dopamine. In both species the response to VIP was predominantly localized to the epithelial fraction. In the human tissue activation of the enzyme could also be achieved with prostaglandin E1 (PGE1) and an alpha 2 adrenergic agonist both associated with the stromal compartment. Castration in the rat caused a marked reduction in the basal activity of the enzyme and the maximal level of the hormone-stimulated response per cell (per mg DNA), but had only minor effects on the pattern of activation when expressed per mg membrane protein. Androgen treatment (dihydrotestosterone propionate, 2.5 mg/day) prevented the castration effects. Estrogen treatment (estradiol benzoate, 125 micrograms/day) could not prevent the castrational changes but maintained enzyme activity at a level above that of the castrate. There were no major qualitative differences in the pattern of activation of the cyclase between the different lobes of the rat prostate and the seminal vesicle.

Adenylyl Cyclases↗
PubMed1986

5 Alpha-reductase in the non-secretory cells of the rat ventral prostate epithelium.

Kinetic constants for the 5 alpha-reductase were determined in freshly isolated epithelial cells from the rat ventral prostate. Studies were also performed on stromal tissue but not isolated stromal cells for comparison. Secretory and non-secretory epithelial cells were separated by centrifugation in a Percoll gradient. Both epithelial cell populations metabolized testosterone to predominantly 5 alpha-dihydrotestosterone (5 alpha-DHT), although when expressed per cell the capacity for conversion was 3-4-fold higher for secretory cells (7.4 pmol/min/10(6) cells) than for non-secretory cells (2.3 pmol/min/10(6) cells; P less than 0.01 in 4 separate studies). When compared per mg cytosol protein this difference became non-significant. Stromal tissue contained a 5 alpha-reductase Vmax (expressed) per mg protein) which was comparable to the non-secretory cell enzyme. Lineweaver-Burke plots revealed different Km values for the different cell populations (12.5, 5.9 and 4.7 microM for secretory, non-secretory and stromal cells, respectively) suggesting the presence of different isoforms of the enzyme, or differences in the intracellular concentrations of enzyme antagonists.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗