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Biomedical subjects

G N Clarke

Publications and source records attributed to G N Clarke.

At least 19 recordsLinked to original sources
PubMed1998

Quantitative sperm mucus penetration: modified formulae for calculating penetration efficiency.

In 1980 Katz et al. derived a formula for the percentage of successful collisions (PSC) as a quantitative measure of sperm-cervical mucus penetration efficiency. The use of PSC waned after its validity was questioned by reports of values >100% and the observation that PSC varied with the cross-sectional area of the mucus column. The aim of the present study was to develop a more accurate measure of mucus penetration efficiency by correcting the original formula for the effects of sperm depletion in the semen reservoir. Two formulae were derived using different models for the sperm-mucus interaction: (i) each motile spermatozoon was assumed to have an equal chance of mucus penetration on collision; (ii) a select subpopulation of spermatozoa was assumed to penetrate with 100% efficiency on collision. Both modified formulae gave PSC values higher than the original estimates. Under the experimental conditions employed in this work, where large capillaries were used, the depletion corrections ranged from 4 to 46% (n=8, mean 20%) for model (i) and from 190 to 320% (n=8, mean 250%) for model (ii). The invariance of PSC (ii) results with respect to capillary cross-sectional area (1.52 mm2, 31.1%; 5.4 mm2, 28.2%) suggests that the assumptions of model (ii) provide the more accurate description of the sperm-mucus interaction.

Female↗
PubMed1997

Intracytoplasmic sperm injection for treating infertility associated with sperm autoimmunity.

OBJECTIVE: To determine whether intracytoplasmic sperm injection (ICSI) can be used to achieve normal fertilization, embryo cleavage, and pregnancies in cases of sperm autoimmunity. DESIGN: A retrospective analysis of ICSI results in sperm antibody-positive and randomly selected antibody-negative groups. SETTING: University- and hospital-based reproductive research laboratory and tertiary referral IVF program. PATIENT(S): Thirty-nine couples selected on the basis of a strongly positive result for sperm antibodies of immunoglobulin (Ig) G and/or IgA immunoglobulin class in the male partner and a control group of 140 antibody-negative couples. INTERVENTION(S): Human menopausal gonadotropin, hCG and Lucrin (Abbott Australasia, Kurnell, NSW, Australia) were given by injection. Oocyte collection was by transvaginal ovarian puncture. Blood was collected for beta-hCG measurement. MAIN OUTCOME MEASURE(S): Normal fertilization, embryo cleavage, establishment of clinical pregnancy, and delivery. RESULT(S): There were no significant differences in fertilization rates (62% versus 58%) or clinical pregnancy rates (19% versus 12%) between sperm antibody-positive and sperm antibody-negative patient groups. CONCLUSION: Intracytoplasmic sperm injection is an effective treatment for patients with severe sperm autoimmunity.

Autoantibodies↗
PubMed1997

A simple monthly means chart system for monitoring sperm concentration.

A simple, robust monthly means chart system for monitoring sperm concentration was developed and used in our andrology laboratory. The system relied on the central limit theorem to allow estimation of chart limits without resorting to data transformation procedures. Once the chart was drawn up, the arithmetic mean of sperm concentration was determined monthly and plotted. Monthly means which fell outside 2 SE from the baseline mean were investigated. Initial experience with this chart system suggests that it provides a simple and useful quality assurance method which should be applicable to other semen variables such as motility and sperm morphology.

Humans↗
PubMed1997

Artificial insemination and in-vitro fertilization using donor spermatozoa: a report on 15 years of experience.

Donor insemination (DI) using cryopreserved semen commenced at The Royal Women's Hospital in 1976. Over the next 15 years we performed 5953 treatment cycles to achieve 816 pregnancies (13.7% per cycle) and 706 live births. In-vitro fertilization (IVF) using donor spermatozoa commenced in 1986. Over the next 5 years we performed 303 treatment cycles for 185 couples. Including subsequent transfer of cryopreserved embryos, a total of 33% of couples achieved a successful pregnancy by IVF. Statistical analysis indicated that, for DI pregnancies, the most important semen variable was the percentage post-thaw motility, whilst for normal fertilization in IVF it was the pre-freeze motility. These results may be explained by the compensatory effects of post-thaw processing of spermatozoa for IVF, but not for DI in our clinic.

Adolescent↗
PubMed1997

A simplified quantitative cervical mucus penetration test.

A simplified quantitative cervical mucus penetration test was developed and applied to the semen of 21 prospective donors in order to evaluate its performance. Analysis of the data using stepwise multiple regression revealed that the concentration of spermatozoa in mucus was related primarily to the concentration of progressive spermatozoa in the semen (63% of variance explained), and secondarily to the average path velocity of spermatozoa in semen (70% of variance explained by a model incorporating both variables). However, consistent with previous studies, the derived indices of penetration efficiency including the percentage successful collisions (PSC), percentage successful entries (PSE) and the motile density ratio (MDR) were not significantly correlated with any of the semen variables examined, although multiple regression did derive models which explained 27-31% of the variance in these three dependent variables. The strong correlation and correspondence between the PSC and the MDR suggests that the latter may provide a simplified index of penetration efficiency for routine clinical use and further research in this area.

Cervix Mucus↗
PubMed1997

Does PTSD transcend cultural barriers? A study from the Khmer Adolescent Refugee Project.

OBJECTIVE: To determine whether the factor structure of the posttraumatic stress disorder (PTSD) syndrome in Cambodian refugee youth resembles earlier reported factor studies in Caucasian samples. METHOD: 194 Khmer adolescent refugees who reported prior significant trauma (most of it massive war trauma as children) were administered the PTSD module of the Diagnostic interview for Children and Adolescents, as part of an epidemiological study on the effects of war on this group of refugees. RESULTS: The following four factors were found: arousal, avoidance, intrusion, and numbing. A confirmatory factor analysis using data from the parents of this sample yielded a good fit for the four-factor solution based on the youth data. CONCLUSIONS: The four-factor solution from this sample resembled earlier studies on traumatized Caucasian and African-American adults. These results lend further credibility to the veracity of this diagnosis with refugee samples. PTSD as a result of prior war trauma appears to surmount the barriers of culture and language in this sample.

Adolescent↗
PubMed1997

Assertive community treatment versus usual care in engaging and retaining clients with severe mental illness.

OBJECTIVE: Two assertive community treatment teams were compared with a usual-care control condition based on their ability to engage and retain clients with serious and persistent mental illness in community-based mental health services. METHODS: Clients were randomly assigned to one of two assertive community treatment teams (N = 116) or to usual care (N = 58). Survival analysis was used to compare clients' length of engagement and retention in service in the two treatment conditions and in usual care. Cox regression analyses were conducted to determine whether demographic, program, or client variables were significantly associated with length of retention in treatment. Data on these baseline variables were collected after clients made initial contact with their community mental health provider. Clients were observed for up to 870 days. RESULTS: By the end of the observation period, the assertive community treatment teams retained 68 percent of their clients, compared with 43 percent in usual care. In both types of treatment, clients were at greatest risk of dropping out of services during the first nine months. The risk of dropout was associated with the type of treatment. Usual-care clients were more than twice as likely as assertive community treatment clients to drop out for reasons related to dissatisfaction with treatment. Each additional night homeless during the six months before enrollment in the study resulted in a 14 percent increase in the probability of dropout. CONCLUSIONS: Assertive community treatment clearly demonstrated a greater ability than usual care services to engage and retain clients in community mental health care.

Adult↗
PubMed1996

Effects of a multidimensional anabolic steroid prevention intervention. The Adolescents Training and Learning to Avoid Steroids (ATLAS) Program.

OBJECTIVE: To test a team-based, educational intervention designed to reduce adolescent athletes' intent to use anabolic androgenic steroids (AAS). DESIGN: Randomized prospective trial. SETTING: Thirty-one high school football teams in the Portland, Ore, area. PARTICIPANTS: Seven hundred two adolescent football players at experimental schools; 804 players at control schools. INTERVENTION: Seven weekly, 50-minute class sessions were delivered by coaches and student team leaders, addressing AAS effects, sports nutrition and strength-training alternatives to AAS use, drug refusal role play, and anti-AAS media messages. Seven weight-room sessions were taught by research staff. Parents received written information and were invited to a discussion session. MAIN OUTCOME MEASURES: Questionnaires before and after intervention and at 9- or 12-month follow-up, assessing AAS use risk factors, knowledge and attitudes concerning AAS, sports nutrition and exercise knowledge and behaviors, and intentions to use AAS. RESULTS: Compared with controls, experimental subjects at the long-term follow-up had increased understanding of AAS effects, greater belief in personal vulnerability to the adverse consequences of AAS, improved drug refusal skills, less belief in AAS-promoting media messages, increased belief in the team as an information source, improved perception of athletic abilities and strength-training self-efficacy, improved nutrition and exercise behaviors, and reduced intentions to use AAS. Many other beneficial program effects remained significant at the long-term follow-up. CONCLUSIONS: This AAS prevention program enhanced healthy behaviors, reduced factors that encourage AAS use, and lowered intent to use AAS. These changes were sustained over the period of 1 year. Team-based interventions appear to be an effective approach to improve adolescent behaviors and reduce drug use risk factors.

Adolescent↗
PubMed1996

The Adolescents Training and Learning to Avoid Steroids (ATLAS) prevention program. Background and results of a model intervention.

OBJECTIVE: To develop and test a school-based intervention to prevent anabolic androgenic steroid use among high-risk adolescent athletes. DESIGN: Nonrandom controlled trial. SETTING: Two urban high schools. PARTICIPANTS: Fifty-six adolescent football players at the experimental school and 24 players at the control school. INTERVENTION: Eight weekly, 1-hour classroom sessions delivered by the coach and adolescent team leaders, and eight weight-room sessions delivered by research staff. The intervention addressed sports nutrition and strength training as alternatives to steroid use, drug refusal role play, and antisteroid media campaigns. OUTCOME MEASURES: A preintervention and postintervention questionnaire that assessed attitudes toward and intent to use steroids and other drugs; knowledge of drug effects; and diet, exercise, and related constructs. RESULTS: Compared with controls, experimental subjects were significantly less interested in trying steroids after the intervention, were less likely to want to use them even if their friends used them, were less likely to believe steroid use was a good idea, believed steroids were more dangerous, had better knowledge of alternatives to steroid use, had improved body image, increased their knowledge of diet supplements, and had less belief in these supplements as beneficial. CONCLUSIONS: Significant beneficial effects were found despite the sample size, suggesting that the effects of the intervention was large. This outcome trial demonstrates an effective anabolic androgenic steroid prevention program for adolescent athletes, and the potential of team-based interventions to enhance adolescents' health.

Adolescent↗
PubMed1996

The Khmer Adolescent Project: III. A study of trauma from Thailand's Site II refugee camp.

OBJECTIVE: To determine the prevalence rates of posttraumatic stress disorder (PTSD) and depression in a sample of 99 Cambodian youths, aged 18 to 25 years, living in the Site II refugee camps along the Thai-Cambodian border; to compare these rates to data collected in a similarly aged sample of Cambodian refugees living in the United States; and to illustrate the findings with case vignettes and a brief description of the refugee camp at Site II. METHOD: The senior author describes the main features of life in the Site II camp while being employed in one of its medical clinics. A Khmer translated version of the depression section of the Schedule for Affective Disorders and Schizophrenia for School-Age Children-Epidemiologic Version and the PTSD section of Diagnostic Interview Schedule for Children and Adolescents were used in interview format by trained bilingual research assistants. Khmer versions of the Beck Depression Inventory and the Impact of Events Scale were also administered. RESULTS: The enduring nature of PTSD was evident in this sample of Khmer youths who had survived the Pol Pot regime as children. Similar rates of Pol Pot-related PTSD were found when compared to rates from the US sample. Subclinical forms of PTSD were found in those who reported their worst trauma during life in the camp, while the full PTSD syndrome was associated with those who reported trauma occurring during the earlier Pol Pot regime. Extremely high rates of depressive disorder were found which were interpreted as related to the repatriation back to Cambodia as this study was undertaken. CONCLUSION: PTSD in this sample appears to be specifically related to earlier war trauma, while depressive symptoms appear more related to recent stressors. As with other findings from the Khmer adolescent project, this study reaffirms the strong connection between the diagnosis of current PTSD and earlier war trauma in an additional sample of youths at Site II, Thailand. Depressive symptoms, on the other hand, appear to be related to the vicissitudes of recent stressful events in this refugee population.

Adolescent↗
PubMed1996

Multiple forms of stress in Cambodian adolescent refugees.

A sample of 170 Cambodian youth and 80 of their mothers were interviewed regarding DSM-III-R diagnoses of Post Traumatic Stress Disorder (PTSD) and depressive disorders, and the stress of war trauma, resettlement, and recent life events. A consistent relation between earlier war trauma, resettlement stress, and symptoms of PTSD was found. In contrast, the strongest relation with depressive symptoms was found for recent stressful events. Despite the long interval of time since the occurrence of the war trauma, these youth and their parents reported these experiences in a highly consistent fashion. PTSD and depression in refugee youth appear to be different conditions following different pathways during adolescent development.

Acculturation↗
PubMed1995

Normal fertilization and embryo development by intracytoplasmic sperm injection of round-headed acrosomeless sperm.

OBJECTIVE: To investigate the ability of round-headed acrosomeless sperm to bind to the human zona pellucida (ZP) and oolemma and to fertilize human oocytes by intracytoplasmic sperm injection. DESIGN: Oocytes that had failed to fertilize in IVF were used for sperm-ZP and spermoolemma binding tests. Sperm from a fertile donor was used as a control for oocyte variability. Intracytoplasmic sperm injection was used for assisted fertilization. SETTING: University- and hospital-based reproductive research laboratory and tertiary referral IVF program. PATIENTS: Case study of a couple in which the man has 100% round-headed acrosomeless sperm in the ejaculate. MAIN OUTCOME MEASURE: Fertilization and embryo development and the ability of sperm to bind to the ZP and oolemma. RESULTS: No ZP or oolemma binding was achieved, but normal fertilization and embryo development was obtained after intracytoplasmic injection of round-headed acrosomeless sperm. However, no pregnancy was achieved after the transfer of two cleaving embryos. CONCLUSIONS: Normal fertilization and embryo development from round-headed acrosomeless sperm is possible with intracytoplasmic sperm injection. However, it remains to be reported whether pregnancy can result from fertilization with this type of sperm defect.

Acrosome↗
PubMed1995

Improving the transition from basic efficacy research to effectiveness studies: methodological issues and procedures.

This article proposes methodological strategies that, if used in treatment outcome research, may help in the transition of efficacy research findings into effectiveness trials in clinical and service delivery settings. Alternative methodologies are proposed to examine how treatment effectiveness may vary as a function of degree of treatment structure, treatment protocol compliance, psychotherapy integration into an overall treatment regimen, participant selection and composition, and variations in treatment parameters. The discussion focuses on encouraging the retention of experimental control while stretching psychotherapy outcome research designs to encompass effectiveness issues.

Adolescent↗
PubMed1995

Sperm preparation for intracytoplasmic injection: methods and relationship to fertilization results.

Sperm preparation for intracytoplasmic sperm injection (ICSI) is described and the effect of high speed centrifugation during preparation on fertilization rate is evaluated. No significant differences were found in the 2-pronuclear or abnormal fertilization rates between sibling oocytes injected with sperm prepared by swim-up or mini-Percoll combined with high speed centrifugation. The high fertilization rate obtained with both methods indicates that high speed centrifugation is not necessary to prepare sperm for ICSI. Fertilization rates were also compared for sperm obtained from ejaculates, fresh and frozen epididymal aspirates, and testicular biopsies. High fertilization rates were obtained from all groups but they were significantly higher in those oocytes injected with epididymal sperm (78% per oocyte surviving injection). The high fertilization rate with epididymal sperm may reflect sperm quality or may result from the method of sperm preparation for injection. Fertilization after the injection of sperm from which the tail was dislodged during immobilization was compared with that obtained using intact sperm. A significantly lower rate of 2-pronuclear fertilization was found in those oocytes injected with sperm heads only (55%) compared with intact sperm (68%), although cleavage rates between the two groups were similar. The use of hypo-osmotic medium to select potentially live sperm from an immotile sample is also described and fertilization was obtained after the injection of sperm with a structural defect which were selected using this technique. These results indicate that high fertilization rates can be obtained with ejaculated, epididymal and testicular sperm without special treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Separation↗
PubMed1995

Targeted prevention of unipolar depressive disorder in an at-risk sample of high school adolescents: a randomized trial of a group cognitive intervention.

OBJECTIVES: This investigation attempted to prevent unipolar depressive episodes in a sample of high school adolescents with an elevated risk of depressive disorder. METHOD: Adolescents at risk for future depressive disorder by virtue of having elevated depressive symptomatology were selected with a two-stage case-finding procedure. The Center for Epidemiologic Studies-Depression Scale (CES-D) was administered to 1,652 students; adolescents with elevated CES-D scores were interviewed with the Schedule for Affective Disorders and Schizophrenia for School-Age Children. Subjects with current affective diagnoses were referred to nonexperimental services. The remaining 150 consenting subjects were considered at risk for future depression and randomized to either a 15-session cognitive group prevention intervention or an "usual care" control condition. Subjects were reassessed for DSM-III-R diagnostic status after the intervention and at 6- and 12-month follow-up points. RESULTS: Survival analyses indicated a significant 12-month advantage for the prevention program, with affective disorder total incidence rates of 14.5% for the active intervention, versus 25.7% for the control condition. No differences were detected for nonaffective disorders across the study period. CONCLUSION: Depressive disorder can be successfully prevented among adolescents with an elevated future risk.

Adaptation, Psychological↗
PubMed1995

Posttraumatic stress disorder across two generations of Cambodian refugees.

OBJECTIVE: To examine the expression of war-related trauma as manifested by DSM-III-R rates of posttraumatic stress disorder (PTSD) and major depressive disorder in two generations of Cambodian refugees living in the western United States. METHOD: A probability sample of 209 Khmer adolescents and one of their parents were interviewed using portions of the Schedule for Affective Disorders and Schizophrenia for School-Age Children-Epidemiologic Version and the PTSD section of the Diagnostic Interview for Children and Adolescents. Interviews were conducted in English by a master's-level clinician with a Khmer interpreter. RESULTS: PTSD was found to be significantly related across parent-child generations. A nonsignificant generational trend was also found for depressive disorders. A number of environmental variables measured in the study (amount of reported war trauma, loss, living arrangements, treatment received, socioeconomic status) were not related to these findings. Parents were more likely to report an earlier onset of PTSD symptoms. CONCLUSIONS: This study suggests that PTSD in refugees may cluster in families. Whether this phenomenon is caused by a genetic susceptibility to trauma awaits further research. PTSD and depressive disorders in refugee populations, while often comorbid, appear to follow different courses over time.

Adolescent↗
PubMed1995

Assessment of the Sperm Quality Analyzer.

OBJECTIVE: To assess the relationship between the results of the Sperm Quality Analyzer (United Medical Systems Inc., Santa Ana, CA), which measures motile sperm concentration by light scattering, conventional manual semen analysis characteristics, and computer-assisted sperm motility analyses. DESIGN: Sperm Quality Analyzer measurements and manual and computer-assisted semen analyses were performed on 150 (50, 62, and 38) samples in three laboratories and the results were compared. SETTING: The study was performed in the Andrology Laboratory of Prince Henry's Institute of Medical Research, Monash Medical Centre, and Andrology Laboratory and Reproductive Biology Unit at the Royal Women's Hospital, Melbourne, Victoria, Australia. PATIENTS: Patients presented to the laboratories for routine fertility evaluation in the male and were selected at random to reflect the range of normal and abnormal samples seen in the laboratories. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Sperm count, motility (percent motility, motility index, velocity, and amplitude of lateral head displacement [ALH]), morphology, and normal acrosomes were evaluated by manual and computer-assisted semen analysis and sperm quality analyzer motility index. RESULTS: Spearman nonparametric univariate analysis showed strong correlations between sperm motility index and manual sperm concentration, motility, abnormal morphology, and normal acrosomes by Pisum sativum agglutinin; and computer-assisted sperm motility analysis sperm concentration, motile concentration, and percent static. Curvilinear velocity, straight-line velocity (VSL), and linearity also were related significantly to sperm motility index values. By multiple regression analysis, the significant covariates of the sperm motility index were motile sperm concentration, abnormal morphology, ALH, and straight-line velocity and these accounted for 85.5% of the variance of the sperm motility index. CONCLUSIONS: The Sperm Quality Analyzer is easy to use. The good correlation between the sperm motility index, motile sperm concentration, and, in addition, a number of other semen parameters supports the use of the Sperm Quality Analyzer for screening patients and in situations that warrant a rapid verification of semen quality, such as in the IVF or artificial insemination clinic. Further investigation of the Sperm Quality Analyzer in the management of male infertility is warranted.

Acrosome↗