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Biomedical subjects

A Leung

Publications and source records attributed to A Leung.

At least 55 records · Page 3Linked to original sources
PubMed1995

Involvement of apoptosis in the induction of germ cell degeneration in adult rats after gonadotropin-releasing hormone antagonist treatment.

In adult mammals, including man, germ cell death is conspicuous during spermatogenesis and plays a pivotal role in sperm output. The possible mechanism(s) underlying this phenomenon remains, however, poorly understood. Apoptosis is a programmed physiological process by which cells die either spontaneously or in response to changes in the levels of specific physiological stimuli. Previously, we reported that early deprivation of gonadotropin and testosterone by GnRH antagonist (GnRH-A) treatment is followed by a stage-specific degeneration of germ cells in the testis. In this study, we examined the possible involvement of apoptosis in the induction of germ cell degeneration. Adult male rats were given a daily injection of Nal-Glu GnRH-A (1 mg/kg BW) for 0 (control), 2, or 5 days. The onset of germ cell degeneration was assessed by high resolution light microscopy as well as by a germ cell degeneration assay. The occurrence of apoptosis was characterized by 1) detection of internucleosomal DNA fragmentation after agarose gel electrophoresis, and 2) direct immunoperoxidase detection of digoxigenin-labeled genomic DNA in specific cell types. The earliest morphological signs of germ cell degeneration involving preleptotene and pachytene spermatocytes, step 7 spermatids (at stage VII), and step 19 spermatids (at both stages VII and VIII) were detected 5 days after the commencement of GnRH-A treatment. The onset of germ cell degeneration was further accompanied by a significant increase in the degree of low mol wt DNA fragmentation. In situ detection of apoptosis within this time frame fully corroborates the observed stage-related degeneration of specific germ cells. These results suggest that apoptosis provides the basic mechanism by which germ cells die in the testis in response to a lack of hormonal stimulation.

Animals↗
PubMed1994

Undetectable levels of serum FSH immunoactivity and bioactivity in girls with sexual precocity due to ovarian cysts.

Clinical presentation and endocrine investigations in five girls with precocious sexual development due to ovarian cysts are presented. These girls had pubertal oestradiol and suppressed gonadotrophin responsiveness to LHRH stimulation. FSH bioactivity as measured by the rat aromatase assay was undetectable in basal and LHRH-stimulated serum samples but our results cannot exclude the possibility of the presence of a species-specific follicle stimulating factor in these patients. IM injection of depot medroxyprogesterone acetate controlled pubertal development in two children.

Child↗
PubMed1994

Comparison of a conventional probe with electronic and manual pressure-regulated probes.

We compared the accuracy, consistency, time, comfort, and cost of probing with a conventional hand probe (CP) with 3-mm banded markings, a manual pressure-regulated probe (MP), and two electronic probes (IP and FP). Twenty (20) examiners used all four probes on a test block to determine accuracy; measurements compared favorably to the reference block. Two calibrated examiners probed the Ramfjord teeth of 10 periodontal patients on maintenance regimens, six sites per tooth (n = 708), with all four probes; measurements were repeated after one week. Wilcoxon signed-rank test showed the CP measured more deeply (P < 0.0001) than MP, FP, and IP with mean differences of 0.40, 0.67, and 0.58 respectively. MP measured more deeply (P < 0.001) than FP and IP, with mean differences of 0.27 and 0.18 mm. There was no difference between FP and IP. Time (min:sec) required by one examiner to perform full mouth probing on six subjects (minimum of 26 teeth each) was CP = 3:59; MP = 4:18; FP = 6:16; and IP = 7:23. Subjects rated FP and IP as slightly more uncomfortable than CP or MP. Cost per 1,000 uses was computed based on available data. The IP and FP took longer to perform and cost more per procedure than did the CP and MP. Spearman rank-order correlation revealed that only probe depths measured by CP and MP were well correlated (rs = 0.67). Although some statistically significant differences were found between probes, no differences were considered to be of clinical significance when probing periodontally healthy or maintenance patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Calibration↗
PubMed1993

Deamidation of HPr, a phosphocarrier protein of the phosphoenolpyruvate:sugar phosphotransferase system, involves asparagine 38 (HPr-1) and asparagine 12 (HPr-2) in isoaspartyl acid formation.

Histidine-containing protein, HPr, of the phosphoenolpyruvate:sugar phosphotransferase system in Escherichia coli, when incubated at elevated temperatures forms many species of protein. The two major species are HPr-1 and HPr-2, which have been shown to lack one or two amides, respectively (Anderson, B., Weigel, N., Kundig, W., and Roseman, S. (1971) J. Biol. Chem. 246, 7023-7033). The formation of HPr-1 and HPr-2 is shown to be pH-dependent and does not occur readily below pH 6. Investigation of the identities and properties of the two residues that deamidate involved creation of site-directed mutants at the 6 glutamine and 2 asparagine residues of HPr; description of their deamidation species by isoelectric focusing; determination of their relative antibody binding properties; assay of their phosphoacceptor and phosphodonor activities; characterization of tryptic and V8-protease peptides; obtaining two-dimensional nuclear magnetic resonance spectra of HPr, HPr-1, and several mutants. It was determined that the sequential deamidation of Asn-38 and Asn-12 yields HPr-1 and HPr-2. Both residues exist as Asn-Gly pairs, and both deamidations probably form isoaspartyl acid. HPr from Bacillus subtilis and Staphylococcus carnosus which also have Asn-Gly at residues 38 and 39 form HPr-1 species presumably by deamidation. HPr from Streptococcus faecalis which does not have Asn-38 does not form a HPr-1 species. The E. coli mutant HPrs, N12D and Q51E, residues that may be involved in the active site, had impaired phosphohydrolysis properties and decreased phosphoenolpyruvate:sugar phosphotransferase system activity.

Amino Acid Sequence↗
PubMed1993

Intrathoracic paediatric tuberculosis: a report of 202 cases.

Until recently paediatric tuberculosis rates were in decline in developed countries, but more recently there has been a significant change in these trends. Tuberculosis in British Columbia (BC) is centralized and all paediatric cases diagnosed between 1979 and 1988 were reviewed. There were 252 notifications during the study period but 50 cases were excluded (31 extrapulmonary cases, 11 with missing records and 8 because of incorrect diagnoses). There were 109 (54%) female patients. The age range was 4 months-15 years (6.4 +/- 4.1 years). 52% were 5 years old or less. 75 (37.1%) were aboriginal Canadians, 61 (30.2%) were Asian, 50 (24.8%) were Caucasian and 16 (8%) were included in miscellaneous or unknown groups. Primary pulmonary disease occurred in 197 (97.5%); the remaining 5 had post-primary disease. A history of close contact was elicited in 158 children (78.2%). All but 8 (4%) had a positive PPD response to 5TU. 40% of children had symptoms, the most frequent being cough (51%) and fever (28.4%). Mycobacteriology was carried out in 169 (83.7%) children. Bacteriologic confirmation was achieved in 45 patients (22.2%). Chest X-rays were reviewed in 186 cases. Lymphadenopathy occurred in 93.5%, with hilar (34%) and combined hilar-paratracheal (26%) being the commonest findings. The majority of patients were treated with isoniazid and rifampin, with a minority receiving streptomycin or pyrazinamide in the initial intensive phase. 14 (6.9%) children had adverse reactions to their drugs but these were rapidly reversed with the withdrawal of the responsible drug. Response to therapy was excellent and there were no deaths.

Adolescent↗
PubMed1993

Assessment of human sperm acrosome reaction by flow cytometry: validation and evaluation of the method by fluorescence-activated cell sorting.

OBJECTIVE: To determine the applicability of flow cytometry to assess human sperm acrosome reaction. DESIGN: Prospective evaluation of semen samples incubated overnight for the development of spontaneous acrosome reaction or exposed to the calcium ionophore A23187 (5 microM) for 3 hours for induction of the acrosome reaction. SETTING: University-affiliated tertiary care center. PATIENTS: Normal healthy volunteers. INTERVENTIONS: The spermatozoa were stained with fluorescein isothiocyanate (FITC)-labeled pea agglutinin. The labeled samples were assessed visually and also subjected to analytic flow cytometry and fluorescence-activated cell sorting. MAIN OUTCOME MEASURES: Acrosome reaction assessed visually and by flow cytometry. RESULTS: Flow cytometric analysis showed a single peak of FITC fluorescence in the washed semen samples. A second peak of lower FITC fluorescence intensity was noted after overnight incubation or exposure to A23187, suggesting loss of fluorescence, which indicated the occurrence of the acrosome reaction. There was a statistically significant correlation between the assessment by the two methods (n = 41). However, although the mean difference between the methods was small (2.49%), the difference between the two methods for each individual sample can vary between -24% to +29%. When the sperm cells were subjected to cell sorting based on green fluorescence intensity, reanalysis and visual scoring verified that the low intensity peak contained a majority of acrosome-reacted spermatozoa (77.52% +/- 2.39%). CONCLUSION: These results validated the flow cytometric method for assessment of acrosome-reacted spermatozoa. Although flow cytometry is more objective and less time consuming when many samples are assessed at the same time, the visual method remains a useful and practical procedure in the clinical andrology laboratory.

Acrosome↗
PubMed1993

Synchrony of cell spreading and contraction force as phagocytes engulf large pathogens.

A simple micromechanical method has been used to directly measure the force of contraction in single mammalian phagocytes (blood granulocytes) during engulfment of large yeast pathogens. Both the time course of cell spreading over the yeast particle and increase in cell body contractile force were quantitated at three temperatures in the range of 23-35 degrees C. The surprising feature of the phagocyte response was that engulfment and cell body contraction occurred in a serial sequence: i.e., the phagocyte spread rapidly over the particle at a steady rate with no detectable cell body contraction; when spreading stopped, contraction force in the cell body then rose steadily to a plateau level that remained stationary until the next sequence of spreading and contraction. Both spreading and contraction exhibited abrupt start/stop kinetics. Also impressive, the cell contraction force stimulated by phagocytosis was quite large (approximately 10(-8) N)-two orders of magnitude larger than the force necessary to deform passive phagocytes to the same extent. If distributed uniformly over the cell cross section, the contraction force is equivalent to an average contractile stress of approximately 10(3) N/m2 (0.01 Atm). These physical measurements in situ set critical requirements for the mechanism of force generation in granulocytes, imply that a major increase in network cross-linking accompanies build-up in contractile force and that subsequent network dissolution is necessary for locomotion.

Biomechanical Phenomena↗
PubMed1993

Human spermatozoal tail hypo-osmotic swelling test, motility characteristics in hypotonic saline, and survival of spermatozoa after cryopreservation.

Normozoospermic semen samples (n = 82) were examined to investigate whether the degree of sperm tail swelling in hypo-osmotic medium (fructose and sodium citrate; 150 mOsm/l), and motility characteristics after a 15-min exposure to hypotonic saline (sodium chloride; 150 mOsm/l) could predict the cryosurvival rate (% post-thaw motility/% pre-freeze motility x 100%) of spermatozoa after cryopreservation by the liquid nitrogen vapour freezing method using the TEST-glycerol-egg yolk buffer. The CellSoft automated semen analyser was used to analyse sperm motility in pre-freeze and post-thaw semen samples, and after exposure to hypotonic saline. Sperm tail hypo-osmotic swelling and sperm motility in pre-freeze semen showed no significant correlations (P > 0.05) with the cryosurvival rate. There were significant correlations (P < 0.05) between the cryosurvival rate and the following sperm motility parameters in hypotonic saline: % motility (r = 0.2846), motility index (% motility x curvilinear velocity; r = 0.2809) and % decrease in motility index from the baseline value in semen (r = 0.3378). The % decrease in motility index after hypotonic saline treatment was significantly less (P < 0.05) in the normal (> or = 50% cryosurvival rate; mean +/- SEM 5.9 +/- 3.2%; n = 33) compared with the subnormal (< 50% cryosurvival rate; 27.3 +/- 4.8%; n = 49) cryosurvival groups. This parameter was also determined, by multivariate discriminant analysis, to be capable of classifying each pre-freeze semen sample into either cryosurvival group with 69.5% accuracy.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Survival↗
PubMed1993

Reproductive aging in the male brown-Norway rat: a model for the human.

Previous studies in the Sprague-Dawley rat have demonstrated that male reproductive aging is primarily a neuroendocrine dysfunction characterized by decreased pulsatile LH secretion leading to low serum testosterone (T) levels, whereas sperm production is relatively well maintained. In contrast to the Sprague-Dawley rat, the Brown-Norway (BN) rat has a longer life span, does not become obese, and experiences fewer age-related tumors of the endocrine or reproductive system, thus providing a disease-free model for studying male reproductive aging. We studied the changes in serum hormone levels and related these alterations to testicular T production, Leydig cell morphometry, and spermatogenesis in young (6 months), aging (22 months), and old (30 months) BN rats. Low serum T levels were associated with decreased LH levels in the 22-month-old (T, 0.58 +/- 0.08 ng/ml; LH, 0.45 +/- 0.06 ng/ml) and 30-month-old rats (T, 0.63 +/- 0.10 ng/ml; LH, 0.34 +/- 0.04 ng/ml) compared to those in young rats (T, 1.35 +/- 0.30 ng/ml; LH, 0.79 +/- 0.10 ng/ml). In vitro Leydig cell T production, basally and after stimulation by LH, was similar in young and old rats. The total testicular T content was lower in 30- than in 6-month-old rats. Testicular morphometry showed smaller Leydig cell volume in the old (857 +/- 97 microns3) than in the young rats (1387 +/- 103 microns3), although their number per testis remained unchanged (6 months, 22.7 +/- 1.6 x 10(6)/testis; 30 months, 25.2 +/- 3.1 x 10(6)/testis). In contrast, a marked (68.4%) reduction in the total number of Sertoli cell per testis was noted in the 30-month-old rats. The proportion of the testis occupied by seminiferous tubules was also reduced in the old rats. Significant (P < 0.05) age-related reductions occurred in tubule diameter, length of tubules, and volume of tubules and their lumens. The testicular sperm concentration and total sperm production were significantly reduced in the 22- and 30-month-old rats. These changes in seminiferous tubule function in the old rats were associated with low serum and testicular inhibin and high serum FSH levels. We conclude that aging in the reproductive axis of the BN rat is manifested by 1) lower serum T levels due to decreased pituitary LH stimulation of endogenous T production, and 2) decreased seminiferous tubule function accompanied by elevated FSH levels indicative of a primary testicular disorder.(ABSTRACT TRUNCATED AT 400 WORDS)

Aging↗
PubMed1993

Human sperm hyperactivation and acrosome reaction and their relationships to human in vitro fertilization.

OBJECTIVE: To determine the relationships between human sperm hyperactivation (HA) and acrosome reaction with fertilization of human oocytes in vitro. DESIGN: Prospective analysis of infertile patients undergoing IVF. SETTING: Tertiary center for infertility and assisted reproductive technology. PATIENTS: Fifty-two couples who underwent IVF or GIFT were studied. The male partners had normal semen parameters on routine analyses. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Sperm HA in seminal fluid and after 1 and 6 hours incubation in capacitation media; sperm acrosome reaction after 0, 6, and 24 hours' incubation in capacitation media; and fertilization rate of human oocytes. RESULTS: The percent spermatozoa with transitional HA after 6 hours of incubation correlated significantly with the fertilization rate of human oocytes. Multivariate discriminant analyses selected six sperm HA and acrosome reaction variables of predictive value in classifying semen samples that achieved fertilization rates above and below 70% threshold. Combination of the selected sperm HA and acrosome reaction variables in seminal fluid and after different times of incubation in capacitation medium classified the samples achieving good or poor fertilization rate with > 80% accuracy. CONCLUSIONS: Assessment of sperm HA and acrosome reaction may be of prognostic value in prediction of human oocyte fertilization rates.

Acrosome↗
PubMed1992

Prophylactic amnioinfusion improves outcome of pregnancy complicated by thick meconium and oligohydramnios.

OBJECTIVE: The null hypothesis is that the use of intrapartum amnioinfusion in labors complicated by the presence of thick meconium and oligohydramnios will not decrease the incidence of fetal distress, cesarean delivery, meconium aspiration, or meconium aspiration syndrome. STUDY DESIGN: One hundred seventy term and postterm patients with thick meconium and oligohydramnios were randomly chosen to receive amnioinfusion or standard obstetric care without amnioinfusion. The frequency of fetal distress, cesarean section, meconium aspiration, and meconium aspiration syndrome were subject to chi 2 analysis, Student's t test, or Fisher's exact test. RESULTS: The rate of fetal distress was significantly reduced in the amnioinfusion group compared with controls (three of 85 vs 19 of 85, relative risk 0.15, 95% confidence interval 0.06 to 0.42). The rate of cesarean section for fetal distress was significantly reduced in the amnioinfusion group (two of 85 vs 17 of 85, relative risk 0.118, confidence interval 0.03 to 0.49). The rates of meconium aspiration (four of 85 vs 33 of 85, relative risk 0.12, confidence interval 0.0449 to 0.327) and meconium aspiration syndrome (0 of 85 vs five of 85, relative risk 0.09, confidence interval 0.009 to 0.872) were significantly reduced by amnioinfusion. CONCLUSIONS: Amnioinfusion improves the outcome in pregnancies complicated by thick meconium and oligohydramnios.

Amnion↗
PubMed1992

Molecular basis for membrane rigidity of hereditary ovalocytosis. A novel mechanism involving the cytoplasmic domain of band 3.

Hereditary ovalocytic red cells are characterized by a marked increase in membrane rigidity and resistance to invasion by malarial parasites. The underlying molecular defect in ovalocytes remained a mystery until Liu and colleagues (N. Engl. J. Med. 1990. 323:1530-38) made the surprising observation that the ovalocytic phenotype was linked to a structural polymorphism in band 3, the anion transporter. We have now defined the mutation in band 3 gene and established the biophysical sequelae of this mutation. This mutation involves the deletion of amino-acids 400-408 in the boundary between the cytoplasmic and the first transmembrane domains of band 3. The biophysical consequences of this mutation are a marked decrease in lateral mobility of band 3 and an increase in membrane rigidity. Based on these findings, we propose the following model for increased membrane rigidity. The mutation induces a conformational change in the cytoplasmic domain of band 3, leading to its entanglement in the skeletal protein network. This entanglement inhibits the normal unwinding and stretching of the spectrin tetramers necessary for membrane extension, leading to increased rigidity. These findings imply that the cytoplasmic domain of an integral membrane protein can have profound effects on membrane material behavior.

Amino Acid Sequence↗
PubMed1992

Direct effects of progesterone and antiprogesterone on human sperm hyperactivated motility and acrosome reaction.

OBJECTIVE: To study the direct effects of progesterone (P) and its antagonist RU486 (mifepristone) on sperm hyperactivation (HA) and acrosome reaction. DESIGN: Prospective evaluation of semen samples incubated in capacitation media with P and/or RU486. SETTING: University-affiliated tertiary care center. PATIENTS: Normal healthy volunteers. INTERVENTIONS: Semen samples were incubated in media with P or RU486 alone or in combination, and aliquots were taken at 10 minutes, 1, 5, and 24 hours for HA analyses by computer-aided sperm analysis system, and at 0, 5, and 24 hours for assessment of acrosome reaction by fluorescein-labeled Pisum sativum (pea) agglutinin. MAIN OUTCOME MEASURES: HA and acrosome reaction. RESULTS: Sperm HA was significantly increased at 10 minutes by P both at 10(-7) M (9.27 +/- 1.59%; mean +/- SEM) and 10(-6) M (9.39 +/- 1.94%) when compared with untreated spermatozoa (5.62 +/- 1.59%). The stimulatory effect of P on sperm HA was transient because this was not observed after 1, 5, and 24 hours of incubation. The antiprogesterone RU486 (10(-6) M) alone had no effect and did not abolish the stimulatory effect of P on HA. The %HA was further enhanced by the addition of RU486 at 10(-6) M to P at 10(-7) M (12.43 +/- 3.31%) or P at 10(-6) M (13.52 +/- 4.10%); however, this effect was not significantly different from P alone. Coincubation of P or RU486 with spermatozoa during capacitation did not stimulate the acrosome reaction in the concentrations tested. CONCLUSION: Progesterone directly stimulates human sperm HA transiently. Progesterone has no significant effect on acrosome reaction in capacitating spermatozoa. The effects of P are rapid and not counteracted by RU486, suggesting that the mechanism of action of P may not be mediated by specific P nuclear receptors.

Acrosome↗
PubMed1991

Detachment of agglutinin-bonded red blood cells. I. Forces to rupture molecular-point attachments.

A simple micromechanical method has been developed to measure the rupture strength of a molecular-point attachment (focal bond) between two macroscopically smooth membrane capsules. In the procedure, one capsule is prepared with a low density coverage of adhesion molecules, formed as a stiff sphere, and held at fixed position by a micropipette. The second capsule without adhesion molecules is pressurized into a spherical shape with low suction by another pipette. This capsule is maneuvered to initiate point contact at the pole opposite the stiff capsule which leads to formation of a few (or even one) molecular attachments. Then, the deformable capsule is slowly withdrawn by displacement of the pipette. Analysis shows that the end-to-end extension of the capsule provides a direct measure of the force at the point contact and, therefore, the rupture strength when detachment occurs. The range for point forces accessible to this technique depends on the elastic moduli of the membrane, membrane tension, and the size of the capsule. For biological and synthetic vesicle membranes, the range of force lies between 10(-7)-10(-5) dyn (10(-12)-10(-10) N) which is 100-fold less than presently measurable by Atomic Force Microscopy! Here, the approach was used to study the forces required to rupture microscopic attachments between red blood cells formed by a monoclonal antibody to red cell membrane glycophorin, anti-A serum, and a lectin from the snail-helix pomatia. Failure of the attachments appeared to be a stochastic function of the magnitude and duration of the detachment force. We have correlated the statistical behavior observed for rupture with a random process model for failure of small numbers of molecular attachments. The surprising outcome of the measurements and analysis was that the forces deduced for short-time failure of 1-2 molecular attachments were nearly the same for all of the agglutinin, i.e., 1-2 x 10(-6) dyn. Hence, microfluorometric tests were carried out to determine if labeled agglutinins and/or labeled surface molecules were transferred between surfaces after separation of large areas of adhesive contact. The results showed that the attachments failed because receptors were extracted from the membrane.

ABO Blood-Group System↗
PubMed1991

Detachment of agglutinin-bonded red blood cells. II. Mechanical energies to separate large contact areas.

As detailed in a companion paper (Berk, D., and E. Evans. 1991. Biophys. J. 59:861-872), a method was developed to quantitate the strength of adhesion between agglutinin-bonded membranes without ambiguity due to mechanical compliance of the cell body. The experimental method and analysis were formulated around controlled assembly and detachment of a pair of macroscopically smooth red blood cell surfaces. The approach provides precise measurement of the membrane tension applied at the perimeter of an adhesive contact and the contact angle theta c between membrane surfaces which defines the mechanical leverage factor (1-cos theta c) important in the definition of the work to separate a unit area of contact. Here, the method was applied to adhesion and detachment of red cells bound together by different monoclonal antibodies to red cell membrane glycophorin and the snail-helix pomatia-lectin. For these tests, one of the two red cells was chemically prefixed in the form of a smooth sphere then equilibrated with the agglutinin before the adhesion-detachment procedure. The other cell was not exposed to the agglutinin until it was forced into contact with the rigid cell surface by mechanical impingement. Large regions of agglutinin bonding were produced by impingement but no spontaneous spreading was observed beyond the forced contact. Measurements of suction force to detach the deformable cell yielded consistent behavior for all of the agglutinins: i.e., the strength of adhesion increased progressively with reduction in contact diameter throughout detachment. This tension-contact diameter behavior was not altered over a ten-fold range of separation rates. In special cases, contacts separated smoothly after critical tensions were reached; these were the highest values attained for tension. Based on measurements reported in another paper (Evans et al. 1991. Biophys. J. 59:838-848) of the forces required to rupture molecular-point attachments, the density of cross-bridges was estimated with the assumption that the tension was proportional to the discrete rupture force x the number of attachments per unit length. These estimates showed that only a small fraction of agglutinin formed cross-bridges at initial assembly and increased progressively with separation. When critical tension levels were reached, it appeared that nearly all local agglutinin was involved as cross-bridges. Because one cell surface was chemically fixed, receptor accumulation was unlikely; thus, microscopic "roughness" and steric repulsion probably modulated formation of cross-bridges on initial contact. To counter the steric repulsion, adhesive contacts were exposed to solutions of a high molecular weight polymer to draw the surfaces together by osmotic dehydration of the adhesion gap. These stresses exceeded initial mechanical assembly stresses by up to three orders of magnitude. As expected, the strength of adhesion was greatly enhanced by the added impingement stress.

Animals↗
PubMed1991

Computer-assisted assessment of human sperm morphology: usefulness in predicting fertilizing capacity of human spermatozoa.

OBJECTIVE: The usefulness of sperm morphology to predict the outcome of human sperm fertilizing capacity was examined. DESIGN, SETTING, PATIENTS: Semen samples from 50 male patients attending the infertility clinic of a tertiary referral institution were studied. MAIN OUTCOME MEASURES: Sperm morphology was classified both by visual assessment and computer-assisted image analysis. In addition, morphometric analysis of the spermatozoa was measured by the morphologizer. Multivariate discriminant analysis was used to evaluate the usefulness of these morphology parameters for predicting the outcome of the zona-free hamster oocyte sperm penetration assay. RESULTS: The manually derived percent of spermatozoa with normal and small head were selected to be of discriminating value in predicting the outcome of the zona-free hamster oocyte penetration test. The accuracy of correctly classifying the outcome of zona-free hamster oocyte penetration test by these two parameters in combination was 84%, whereas assessment of sperm morphology with morphometric analysis by the morphologizer selected a total of eight variables, which together predicted sperm fertilizing capacity with 74% accuracy. Addition of the morphologizer-derived parameters to those derived manually did not significantly improve the predictive value. CONCLUSION: We conclude that the results of the zona-free hamster egg penetration test could be predicted using manual assessment of sperm morphology and computer-assisted morphometric analysis did not add further information.

Animals↗
PubMed1991

Steroidogenesis-stimulating activity in the gonads: comparison of rat testicular fluid with bovine and human ovarian follicular fluids.

The steroidogenesis-stimulating activities of ovarian follicular fluid from bovine (bFF) and human (hFF) sources, were compared with those of adult rat testicular fluid (rTF) using an in vitro bioassay system based on stimulation of testosterone production by purified adult rat Leydig cells during a 20-h incubation. Rat TF and bFF were charcoal-treated to remove steroids prior to assay, and the major active fraction of hFF was collected after gel-permeation chromatography. All three fluid samples stimulated both basal and maximal hCG-stimulated testosterone production, although the resulting log dose-response lines of bFF and the hFF extracts were not parallel with those of rTF. Both rTF and bFF were active over a similar dose range (5.2-150 microliters and 9.7-150 microliters, respectively) and both had a more than additive interaction with hCG on testosterone production. The stimulatory activity of the hFF extract was considerably greater than that of either rTF or bFF in the absence of hCG, but hFF extract had only an additive effect with hCG in stimulating testosterone production. Moreover, unlike rTF activity, which was inhibited by co-incubation with the protein synthesis inhibitor, cycloheximide, the activity of the hFF extract was not affected by cycloheximide. The factors responsible for activity in all three fluids were of a large molecular size (greater than 30 kDa), as determined by ultrafiltration or gel-permeation chromatography. However, in contrast to both rTF and bFF, hFF extract activity was removed by charcoal extraction. Human FF extract was inactivated by heat (100 degrees C, 30 min), whereas rTF activity was partially (70%) heat-labile and bFF was not affected by heart.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗