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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
PubMed2000

Feasibility of surveillance of changes in human fertility and semen quality.

To show that male fertility is declining is not simple. Few men volunteer and recruitment bias may lead to over-representation of the subfertile. Semen analysis has errors arising from counting and poorly standardized criteria, which may be overcome by automation. Time to pregnancy (TTP)-the number of menstrual cycles taken to conceive-measures fertility and allows male recruitment bias to be estimated. We review automated measurement of sperm concentration, motility and morphology and present a preliminary report on a study to assess a retrospective TTP questionnaire, recruitment bias and feasibility for large-scale surveillance of fertility.

Feasibility Studies↗
PubMed1999

Psychosocial treatments for adolescent depression.

Major Depressive Disorders affect between 2% and 5% of adolescents at any one point in time. Depression in adolescence is associated with serious psychosocial deficits and has negative effects on functioning during young adulthood. Starting with the pioneering work of Lenore Butler and her colleagues, many psychosocial interventions have been developed and studied, with generally positive results. On the basis of a meta-analysis of the existing cognitive-behavioral therapy (CBT) studies we estimate an overall effect size of 1.27 and that 63% of patients show clinically significant improvement at the end of treatment. It seems reasonable to conclude that CBT has been demonstrated to be an effective treatment for depressed adolescents. In this article we describe these interventions, most of which are meant to address the problems shown by depressed adolescents. The purpose of our article is to bring this literature to the attention of clinicians in a manner which quickly and clearly summarizes the key features of the interventions to make it easy for clinicians to take advantage of this wealth of information and to avail themselves of the existing resources. We conclude by suggesting future directions and several additional areas of application for adolescent depression treatments.

Adolescent↗
PubMed1999

An important role of actin polymerization in the human zona pellucida-induced acrosome reaction.

The effects of inhibitors of actin polymerization and depolymerization, cytochalasins and phalloidin, on the human zona pellucida (ZP)-induced acrosome reaction (AR) were investigated. Motile spermatozoa, selected by swim-up technique from normozoospermic men, were incubated in medium with or without the actin modulators. Oocytes (four per test) which had failed to fertilize in vitro were added and incubation continued for 2 h. The spermatozoa bound to the ZP were dislodged by repeatedly aspirating the oocytes with a small-bore pipette and the status of the acrosomes was determined by fluorescein-labelled Pisum sativum agglutinin (PSA). Double immunofluorescent staining with PSA and an anti-actin monoclonal antibody illuminated the acrosomal region of acrosome-intact spermatozoa. In calcium ionophore-induced AR spermatozoa, actin staining was confined to the equatorial segment, post-acrosomal region and tail. Cytochalasins B and D significantly inhibited ZP-induced AR in a dose-dependent manner (P < 0.001). Both inhibitors had no effect on the acrosome of spermatozoa in the insemination medium. Cytochalasin B or D (10-40 micromol/l) had no effect on total percentage motile spermatozoa but decreased sperm velocity and hyperactivation. Phalloidin had no effect on the ZP-induced AR or sperm motility. In conclusion, actin polymerization plays an important role in human ZP-induced AR.

Acrosome Reaction↗
PubMed1999

Cognitive-behavioral treatment of adolescent depression: efficacy of acute group treatment and booster sessions.

OBJECTIVE: This trial examined the effects of both acute and maintenance cognitive-behavioral therapy (CBT) for depressed adolescents. METHOD: Adolescents with major depression or dysthymia (N = 123) were randomly assigned to 1 of 3 eight-week acute conditions: adolescent group CBT (16 two-hour sessions); adolescent group CBT with a separate parent group; or waitlist control. Subsequently, participants completing the acute CBT groups were randomly reassigned to 1 of 3 conditions for the 24-month follow-up period: assessments every 4 months with booster sessions; assessments only every 4 months; or assessments only every 12 months. RESULTS: Acute CBT groups yielded higher depression recovery rates (66.7%) than the waitlist (48.1%), and greater reduction in self-reported depression. Outcomes for the adolescent-only and adolescent + parent conditions were not significantly different. Rates of recurrence during the 2-year follow-up were lower than found with treated adult depression. The booster sessions did not reduce the rate of recurrence in the follow-up period but appeared to accelerate recovery among participants who were still depressed at the end of the acute phase. CONCLUSIONS: The findings, which replicate and expand upon a previous study, support the growing evidence that CBT is an effective intervention for adolescent depression.

Adolescent↗
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↗