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Biomedical subjects

B J Rogers

Publications and source records attributed to B J Rogers.

At least 19 recordsLinked to original sources
PubMed1992

Visual and nonvisual information disambiguate surfaces specified by motion parallax.

Motion parallax has been shown to be an effective and unambiguous source of information about the structure of three-dimensional (3-D) surfaces, both when an observer makes lateral movements with respect to a stationary surface and when the surface translates with respect to a stationary observer (Rogers & Graham, 1979). When the same pattern of relative motions among parts of the simulated surface is presented to a stationary observer on an unmoving monitor, the perceived corrugations are unstable with respect to the direction of the peaks and troughs. The lack of ambiguity in the original demonstrations could be due to the presence of (1) non-visual information (proprioceptive and vestibular signals) produced when the observer moves or tracks a moving surface, and/or (2) additional optic flow information available in the whole array. To distinguish between these two possibilities, we measured perceived ambiguity in simulated 3-D surfaces in situations where either nonvisual information or one of four kinds of visual information was present. Both visual and nonvisual information were effective in disambiguating the direction of depth within the simulated surface. Real perspective shape transformations affecting the elements of the display were most effective in disambiguating the display.

Adult↗
PubMed1991

Combined administration of a gonadotropin-releasing hormone antagonist and testosterone in men induces reversible azoospermia without loss of libido.

GnRH antagonists suppress pituitary and gonadal function by competing with endogenous GnRH for binding to receptors on pituitary gonadotrophs. We studied the effects of GnRH antagonist administration to men in a protocol simulating a likely male contraceptive regimen combined with a low dose of testosterone. The GnRH antagonist Nal-Glu was given daily (10 mg, sc) for 20 weeks to eight normal men, and a low dose of testosterone enanthate (25 mg, sc) was given every week. Sperm counts started declining during week 4, and complete azoospermia was reached within 6-12 weeks in six of the eight subjects. Subjects 7 and 8, whose sperm counts and serum gonadotropin levels were not suppressed after 10 weeks, were given 20 mg Nal-Glu starting at week 10. One became azoospermic at week 16, while the other's total sperm counts continued declining and reached a nadir of 1.4 million by week 20. Sperm motility and viability in this subject were completely suppressed after week 14. Sperm counts returned to baseline levels 12-14 weeks after the end of Nal-Glu administration. The mean serum LH level of the first six subjects decreased from 3 +/- 03. U/L at baseline to less than 0.1 U/L until week 20, and then levels returned to baseline. FSH levels similarly decreased from a combined mean of 3.6 +/- 0.9 U/L at baseline to below 0.3 U/L after 4 weeks of Nal-Glu administration. Serum mean testosterone levels between weekly injections of testosterone enanthate ranged from 27.4 +/- 5.9 to 4.8 +/- 1.4 nmol/L, but remained in the hypogonadal range (less than 10 nmol/L) for 4 of the 7 days. None of the subjects, however, complained of decreased libido or potency, as assessed by a questionnaire. No systemic or significant local side-effects were observed, other than a minimal reaction at the injection site. These data suggest that complete sustained azoospermia can be achieved in man, without loss of libido, by chronic administration of a GnRH antagonist plus testosterone.

Adult↗
PubMed1990

Prediction of human sperm penetrating ability using computerized motion parameters.

The sperm penetration assay (SPA) is used to assess male fertilizing potential but it is tedious and costly. Computer analysis could replace the need for the SPA in some cases, if computerized sperm motility parameters are highly predictive of SPA performance. The objective of this study was to determine whether computerized motility parameters from fresh semen samples could be used to predict SPA performance. Computer automated semen analysis (CASA; CellSoft, Cryo Resources) was used to quantitate sperm concentration (CONC), percent motility (MOT), curvilinear velocity (VEL), linearity of swimming trajectory (LIN), mean amplitude of lateral head displacement (ALH), and beat/cross frequency (B/CF). The SPA was performed using either Biggers, Whitten, and Whittingham's medium (BWW) or TEST-yolk buffer (TYB). Patients were divided into three groups depending on SPA performance: group 1, BWW-treated, 0% versus greater than 0% penetration; group 2, TYB-treated, 0% versus greater than 0% penetration; and group 3, TYB-treated, less than 20% versus less than or equal to 20% penetration. SPA performance was highly correlated with CONC, MOT, VEL, and B/CF. CONC, MOT, VEL, and B/CF were significantly higher for patients who penetrated in the SPA than for those who failed to penetrate. Discriminant function analysis (DFA) successfully classified 76% of all patients treated with TYB (group 2) who penetrated and 86% of nonpenetrators based on their computerized motility parameters. For group 2 DFA predicted that 93 men would penetrate in the SPA with TYB. Of these, 90 (97%) successfully penetrated at least one egg.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

The use of gonadotropin releasing hormone agonist (GnRHa) in good responders undergoing repeat in vitro fertilization/embryo transfer (IVF/ET).

The use of gonadotropin releasing hormone agonists (Gn-RHa) has been shown to improve the response in patients classified as "poor responders" undergoing ovarian stimulation for in vitro fertilization/embryo transfer (IVF/ET). This study sought to determine whether GnRHa therapy would benefit patients undergoing IVF/ET who had been classified as "good responders" in prior attempts. Twenty-three patients who had completed a prior IVF/ET attempt but who failed to conceive underwent ovarian stimulation using a combination of GnRHa and human menopausal gonadotropin (hMG). Each patient's prior stimulation served as her control and consisted of clomiphene citrate (CC)/hMG in 18 patients and follicle stimulating hormone (FSH) and/or hMG in 5 patients. The numbers of oocytes retrieved, oocytes fertilized, embryos cleaved, and embryos transferred were all significantly greater in cycles treated with GnRHa/hMG compared to control cycles. The clinical pregnancy rate was 39% and the ongoing pregnancy rate was 26% during the cycle when GnRHa pretreatment was utilized. These data suggest that GnRHa therapy is of benefit even to those patients previously classified as "good responders" undergoing ovarian stimulation for IVF/ET.

Adult↗
PubMed1990

The efficacy of cryopreserved hamster ova in the sperm penetration assay.

To solve the logistical problems of the sperm penetration assay (SPA) to provide just a sufficient number of hamster ova exactly when they are needed, a new method to cryopreserve the ova has been devised. The ova, suspended in a 1.5 M solution of propylene glycol as a cryoprotectant in an isotonic salt solution, were frozen in 1/4 mL plastic straws. Included in each straw was a sucrose solution, isosmotic to the propylene glycol solution, to serve as an osmotic buffer during dilution of the cryoprotectant out of the ova. This one-step method of dilution permitted the ova to be recovered and diluted out of the cryoprotectant within the straw in which they had been originally frozen. A total of 547 cryopreserved ova were thawed, 504 (92.1%) of which were morphologically normal after they had been incubated at 37 degrees C for 3 hours. After removal of the zonae, the frozen-thawed ova were compared with fresh, control ova in SPAs of donor and patient semen that had been capacitated in TEST-yolk buffer. The percent penetration and penetration index of fresh versus cryopreserved ova did not differ significantly for either donor or patient semen.

Analysis of Variance↗
PubMed1990

Establishment of TEST-yolk buffer enhanced sperm penetration assay limits for fertile males.

TEST-yolk buffer has been shown to enhance sperm penetration of zona-free hamster eggs. Review of sperm penetration assay (SPA) data from a fertile population was undertaken to determine a normal range for SPA with TEST-yolk buffer enhancement. Thirty-eight intrauterine insemination patients and 4 artificial insemination donors who had successfully initiated a pregnancy within 18 months of SPA analysis were examined. All 42 enhanced SPAs demonstrated penetration of greater than 10%, and 37 of these (88%) yielded SPA values of greater than or equal to 20%. Thirty-three percent (14/42) of these individuals achieved 0% penetration in the SPA without TEST-yolk buffer. The SPA performed with the TEST-yolk modification has fewer false negatives than the assay done with the original methodology.

Animals↗
PubMed1990

Importance of glycolysable substrates for in vitro capacitation of human spermatozoa.

To investigate the importance of glycolysable substrate for supporting the ability of human sperm to capacitate and penetrate oocytes in vitro, washed spermatozoa were incubated with or without various sugars in BWW culture medium containing pyruvate and lactate. Sperm penetration was assayed using zona-free hamster oocytes. After an 18-h preincubation, glucose (1 mg/ml) supported higher penetration of sperm into oocytes than either mannose or fructose (60.7% vs. 28.2% or 21.5%, respectively) at the same concentration. Penetration was even lower when medium contained the nonmetabolizable sugar galactose (2.1% at 1 mg/ml). On the other hand, higher concentrations (5 or 10 mg/ml) of glucose, but not fructose, suppressed penetration, provided the glucose was present throughout the 18-h preincubation. When caffeine, a stimulant of glycolysis in human sperm, was present along with glucose, sperm penetration was enhanced, but only after 6 h of sperm preincubation. This effect was not observed in glucose-free medium, however, where penetration remained low over a 10-h incubation period. In these experiments, the percentage of motile sperm was unaffected by treatment, but the quality of motility was diminished in the absence of glucose. We conclude that stimulation of glycolysis may promote capacitation of human spermatozoa in vitro and that optimization of penetrating ability of sperm is dependent upon both the type and concentration of glycolysable sugar present.

Animals↗
PubMed1989

Luteinizing hormone and ovulation timing in a therapeutic donor insemination program using frozen semen.

A series of 110 therapeutic donor insemination cycles was analyzed to determine the impact on fecundity when a urinary luteinizing hormone detection kit was used to plan inseminations. To prevent the transmission of human immunodeficiency virus, frozen semen, thawed after a 90-day quarantine, was used. The minimum standard for insemination with cryopreserved semen was a total of 24 x 10(6) motile sperm per milliliter after thawing. Fecundity was 0.12 when insemination timing was based on cervical mucus evaluation and basal body temperature charts and 0.13 when a urinary luteinizing hormone kit was also used to predict ovulation. Life table analysis with the log rank test showed no statistically significant difference in the number of cycles required to achieve conception between the group of patients using conventional methods of ovulation timing and the group of patients using the urinary luteinizing hormone kit. Urinary luteinizing hormone testing offers no advantage over conventional methods, such as cervical mucus examination and evaluation of basal body temperature, when ovulation is being timed for insemination with frozen donor semen.

Acquired Immunodeficiency Syndrome↗
PubMed1989

The human blastocyst produces a soluble factor(s) that interferes with lymphocyte proliferation.

Animal studies have reported that the blastocyst produces immunosuppressive factors that are critical to successful implantation. The production of such factor(s) by the human blastocyst has not yet been described. To test that hypothesis, the spent media of 67 human embryos developed in vitro was evaluated using either the allogeneic one-way mixed lymphocyte response (MLR) or the concanavalin A (Con-A) stimulated lymphocyte response (SLR). Conditioned embryo media was obtained at in vitro fertilization (IVF) in aliquots of (A) the first 24 hours in vitro, (B) the second 24 hours in vitro, and (C) from 24 hours until development of the blastocyst stage. Control media consisted of Ham's F-10 medium (Gibco, Grand Island, NY) with identical maternal serum concentration to test media. Conditioned media (either A, B, or C) or control media was added to 200-microL wells containing lymphocytes in either the MLR or SLR. A significant suppressive effect of 25% to 60% was observed in seven of nine samples of blastocyst-conditioned media (P less than 0.05). No significant suppressive effect was found in the earlier embryo media (A or B) in either the MLR or the SLR. These data suggest that the human blastocyst produces a factor(s) that interferes with lymphocyte proliferation.

Blastocyst↗
PubMed1989

The influence of oocyte maturity and embryo quality on pregnancy rate in a program for in vitro fertilization-embryo transfer.

An important factor influencing the pregnancy rate after in vitro fertilization-embryo transfer (IVF-ET) appears to be the number of embryos transferred to the uterus. In this study, the influence of oocyte maturity and embryo quality on pregnancy rate was assessed in patients undergoing IVF-ET. Ovarian hyperstimulation was performed by human menopausal gonadotropin (hMG [n = 29]), clomiphene citrate (CC)/hMG (n = 81), and hMG/follicle-stimulating hormone (FSH [n = 13]) protocols. Oocyte maturity was graded on a scale from 1 to 5 based on the morphology of the ooplasm, cumulus mass, corona radiata, and membrana granulosa cells. Embryos were graded according to the symmetry of the blastomeres and the presence or absence of fragmentation. Mature preovulatory oocytes yielded the highest fertilization rates. No differences were found among the protocols in terms of fertilization rate, embryo quality, or pregnancy rate. When all protocols were combined, patients who conceived had a significantly higher number of embryos transferred than those who did not conceive (3.6 +/- 0.1 [mean = SEM] versus 2.7 +/- 0.1). When embryo quality was compared, there was no difference in the number of "B" embryos transferred between patients who conceived and those who did not (1.2 +/- 0.2 versus 1.2 +/- 0.1), but the patients who conceived had significantly more "A" embryos transferred (1.6 +/- 0.3 versus 0.8 +/- 0.1). These data suggest that the treatment protocol did not determine embryo quality. Furthermore, the increase in pregnancy rates seen with an increase in embryos transferred is the result of the transfer of more "A" embryos.

Blastomeres↗
PubMed1989

The appearance of surfaces specified by motion parallax and binocular disparity.

The experiments reported in this paper were designed to investigate how depth information from binocular disparity and motion parallax cues is integrated in the human visual system. Observers viewed simulated 3-D corrugated surfaces that translated to and fro across their line of sight. The depth of the corrugations was specified by either motion parallax, or binocular disparities, or some combination of the two. The amount of perceived depth in the corrugations was measured using a matching technique. A monocularly viewed surface specified by parallax alone was seen as a rigid, corrugated surface translating along a fronto-parallel path. The perceived depth of the corrugations increased monotonically with the amount of parallax motion, just as if observers were viewing an equivalent real surface that produced the same parallax transformation. With binocular viewing and zero disparities between the images seen by the two eyes, the perceived depth was only about half of that predicted by the monocular cue. In addition, this binocularly viewed surface appeared to rotate about a vertical axis as it translated to and fro. With other combinations of motion parallax and binocular disparity, parallax only affected the perceived depth when the disparity gradients of the corrugations were shallow. The discrepancy between the parallax and disparity signals was typically resolved by an apparent rotation of the surface as it translated to and fro. The results are consistent with the idea that the visual system attempts to minimize the discrepancies between (1) the depth signalled by disparity and that required by a particular interpretation of the parallax transformation and (2) the amount of rotation required by that interpretation and the amount of rotation signalled by other cues in the display.

Attention↗
PubMed1989

Concurrent validation of Hutt's Bender Gestalt screening method for schizophrenia, depression, and brain damage.

The effectiveness of Hutt's Bender Gestalt scoring system in screening for schizophrenia, depression, and brain damage was investigated in a sample of mixed, psychiatric inpatients. Fifteen patients represented each diagnostic category. After an examination of each patient's Bender Gestalt protocol according to Hutt's criteria, it was found that the true positive and true negative success rates of the screening procedures for depression and brain damage were significantly higher than corresponding base rates. The Lacks Bender Gestalt screening method for brain damage was no more successful than the Hutt method in identifying true positives and true negatives. With the brain-damaged patients excluded, Hutt's screening procedures for both depression and schizophrenia resulted in significantly high rates of successful identification of true positives and true negatives. Moreover, these rates did not significantly differ from those determined by patients' Minnesota Multiphasic Personality Inventory (MMPI) T scores on corresponding scales.

Adult↗
PubMed1989

Examination of data from programs of in vitro fertilization in relation to sperm integrity and reproductive success.

This paper reviews the work of 11 different in vitro fertilization (IVF) groups from around the world in an effort to determine the effectiveness of IVF as a therapy for male factor infertility as well as threshold values for semen parameters that are synonymous with success. Two key questions that are asked are: 1) What fertilization rate is expected for male factor patients and 2) Can we predict which patients will fertilize. The immediate problem which arises in attempting to compare results from various groups is that there is no standardization in male factor criteria. This lack of agreement in what constitutes an abnormal semen sample is also reflected in the fertilization rates and threshold values. The first group reviewed (Mahadevan, 1983) suggest greater than 20% motile in the initial semen sample as a threshold value required for success while the second group (Cohen, 1985) presents 6 couples with less than 20% motility achieving pregnancy. Such inconsistencies in results are typical of this confusing and controversial area. Fertilization in IVF has been achieved with as few as 2 x 10(6) sperm/ml or as low as only 2% motility in the initial semen sample. It appears that most workers would agree that the lower limits of traditional semen parameters that are compatible with success are not well defined. Consensus might also be reached on the fact that fertilization rates are usually significantly lower in male factor cases than in normal semen parameters coupled with tubal infertility. Beyond those two factors, little agreement is found in the literature. The spectrum of methodology for semen processing is very broad and often not clearly detailed. In addition to the additional semen parameters of count, motility, and morphology, attempts have been made to establish other prognostic tests such as the sperm penetration assay (SPA), acrosome reaction determinations, and motility parameters such as velocity, linearity and lateral head displacement. Controversy abounds concerning the value of these newer tests. Threshold values for acrosome reaction and motility parameters have not been established. The SPA is believed to be highly predictive by some and unreliable by others. The one redeeming feature of this IVF male factor area is that it seems to be one of the most effect treatments for male factor infertility.

Evaluation Studies as Topic↗
PubMed1988

Use of the SPA in assessing toxic effects on male fertilizing potential.

The sperm penetration assay (SPA), which involves the use of zona-free hamster eggs to assess fertilizing potential of human spermatozoa, has the capability of evaluating the functional capacity of sperm. If men are exposed to a toxic insult that could result in impaired fertility, this has been monitored historically by determining the routine semen parameters of concentration, motility, and morphology. The lack of availability of the SPA for evaluating toxic exposure in field studies has hampered its utilization. The purpose of this article is to illustrate the use of the SPA in a specific field study and to describe two recent innovations in the SPA that make its use more accessible for field studies. These two innovations are shipping semen samples in TEST-yolk buffer by overnight express to a central laboratory for testing and using frozen hamster eggs in the test. The report is divided into the following three major sections: I. Kunia study; II. TEST-yolk buffer modifications of SPA; and III. Use of frozen eggs in SPA.

Animals↗
PubMed1988

Dynamic occlusion and motion parallax in depth perception.

Random-dot techniques were used to examine the interactions between the depth cues of dynamic occlusion and motion parallax in the perception of three-dimensional (3-D) structures, in two different situations: (a) when an observer moved laterally with respect to a rigid 3-D structure, and (b) when surfaces at different distances moved with respect to a stationary observer. In condition (a), the extent of accretion/deletion (dynamic occlusion) and the amount of relative motion (motion parallax) were both linked to the motion of the observer. When the two cues specified opposite, and therefore contradictory, depth orders, the perceived order in depth of the simulated surfaces was dependent on the magnitude of the depth separation. For small depth separations, motion parallax determined the perceived order, whereas for large separations it was determined by dynamic occlusion. In condition (b), where the motion parallax cues for depth order were inherently ambiguous, depth order was determined principally by the unambiguous occlusion information.

Attention↗
PubMed1987

Ethanol inhibits human and hamster sperm penetration of eggs.

The effect of alcohol on the fertilizing ability of both human and hamster spermatozoa was examined by an in vitro fertilization assay using hamster ova. Spermatozoa were incubated in capacitating media for 3 hr (hamster sperm) and 4 hr (human sperm). Hamster ova were inseminated with preincubated sperm and were examined after 2 to 3 hr. Ethanol was added to the capacitating media at concentrations of 25, 50, 100, 200, and 400 mg%. Fertilization of zona-free hamster eggs by human spermatozoa was reduced from 49.6% in no alcohol to 16.7% in 400 mg% ethanol. Fertilization of hamster eggs by hamster sperm revealed a reduction from 63.6% to 33.7% in cumulus-intact eggs and from 65.8% to 10.8% in cumulus-free eggs in the presence of ethanol at 400 mg%. Hamster sperm acrosome reaction was reduced from 47% to 12%. When these hamster sperm with reduced acrosome reaction were placed with zona-free hamster eggs, the 100% fertilization rate was not reduced; however, the fertilization index, which reflects the number of swelling sperm heads per egg, was reduced from 8.5 to 1.8. This suggests that as little as 12% of the sperm with an acrosome reaction is sufficient to fertilize 100% of the zona-free eggs. If ethanol was added to the insemination media only, there was no inhibition of fertilization by human sperm or hamster sperm that had been previously capacitated in an ethanol-free media. Removal of the ethanol from the preincubated sperm produced fertilization at control levels; thus the inhibitory effect is reversible. These results indicate that ethanol may affect fertilization by an inhibition of the capacitation and/or acrosome reaction process.

Acrosome↗