Acute and chronic methylphenidate dose-response assessment on three adolescent male rat strains.

Methylphenidate (MPD), commonly known as Ritalin, is the most frequently prescribed drug to treat children and adults with attention deficit hyperactivity disorder (ADHD). Adolescence is a period of development involving numerous neuroplasticities throughout the central nervous system (CNS). Exposure to a psychostimulant such as MPD during this crucial period of neurodevelopment may cause transient or permanent changes in the CNS. Genetic variability may also influence these differences. Thus, the objective of the present study was to determine whether acute and chronic administration of MPD (0.6, 2.5, or 10.0mg/kg, i.p.) elicit effects among adolescent WKY, SHR, and SD rats and to compare whether there were strain differences. An automated, computerized, open-field activity monitoring system was used to study the dose-response characteristics of acute and repeated MPD administration throughout the 11-day experimental protocol. Results showed that all three adolescent rat groups exhibited dose-response characteristics following acute and chronic MPD administration, as well as strain differences. These strain differences depended on the MPD dose and locomotor index. Chronic treatment of MPD in these animals did not elicit behavioral sensitization, a phenomenon described in adult rats that is characterized by the progressive augmentation of the locomotor response to repeated administration of the drug. These results suggest that the animal's age at time of drug treatment and strain/genetic variability play a crucial role in the acute and chronic effect of MPD and in the development of behavioral sensitization.

Estimation of male-to-female ratios of mutation rate in primates and rodents

Haldane (1935) developed a method for estimating the male-to-female ratio of mutation rate ($\alpha$) by using sex-linked recessive genetic disease, but in six different studies using hemophilia A data the estimates of $\alpha$ varied from 1.2 to 29.3. Direct genomic sequencing is a better approach, but it is laborious and not readily applicable to non-human organisms. To study the sex ratios of mutation rate in various mammals, I used an indirect method proposed by Miyata et al. (1987). This method takes advantage of the fact that different chromosomes segregate differently between males and females, and uses the ratios of mutation rate in sequences on different chromosomes to estimate the male-to-female ratio of mutation rate. I sequenced the last intron of ZFX and ZFY genes in 6 species of primates and 2 species of rodents; I also sequenced the partial genomic sequence of the Ube1x and Ube1y genes of mice and rats. The purposes of my study in addition to estimation of $\alpha$'s in different mammalian species, are to test the hypothesis that most mutations are replication dependent and to examine the generation-time effect on $\alpha$. The $\alpha$ value estimated from the ZFX and ZFY introns of the six primate specise is ${\sim}$6. This estimate is the same as an earlier estimate using only 4 species of primates, but the 95% confidence interval has been reduced from (2, 84) to (2, 33). The estimate of $\alpha$ in the rodents obtained from Zfx and Zfy introns is ${\sim}$1.9, and that deriving from Ube1x and Ube1y introns is ${\sim}$2. Both estimates have a 95% confidence interval from 1 to 3. These two estimates are very close to each other, but are only one-third of that of the primates, suggesting a generation-time effect on $\alpha$. An $\alpha$ of 6 in primates and 2 in rodents are close to the estimates of the male-to-female ratio of the number of germ-cell divisions per generation in humans and mice, which are 6 and 2, respectively, assuming the generation time in humans is 20 years and that in mice is 5 months. These findings suggest that errors during germ-cell DNA replication are the primary source of mutation and that $\alpha$ decreases with decreasing length of generation time. ^

Project Alpha: A culturally appropriate approach to adolescent male sex education

In the United States today, adolescents face unacceptably high rates of mortality and morbidity due to the contraction of HIV/AIDS, sexually transmitted diseases and teenage pregnancy. In view of these rates, there is a need for applied preventive interventions to delay adolescent sexual behavior until adulthood. Project Alpha was a school-adopted, quasi-experimental program for adolescent male students attending Sharpstown High School in Houston, Texas. This intervention used student newsletters to provide specific role-model stories on community and student role models who have changed attitudes or improved efficacy to abstain from sexual behavior until adulthood. It was hypothesized that teenagers exposed to the intervention would show improvements in knowledge, beliefs, avoidance skills, perceived norms, intentions and self-efficacy to delay sexual behavior compared to no-treatment reference teenagers in the same school.^ In total, the Project Alpha program had a significant effect on student knowledge, beliefs (towards abstinence and having sex with multiple partners), perceived risk (HIV/STD testing), self-efficacy (could avoid sex with attractive girl who wants to have sex), perceived social norms (friends believing in sexual abstinence) and sexual intentions. However, no significant intervention effects were found in student's beliefs (that it was OK to have sex with girlfriend), perceived risk of HIV/STD, self-efficacy (to avoid sex with girlfriend) and social norms (friends believe it is OK to have sex with a girlfriend and multiple partners in the same month). ^

DIRECT EFFECT OF MELATONIN UPON THE RELEASE OF GONADOTROPINS FROM THE SUPERFUSED PITUITARY GLAND OF THE MALE GOLDEN HAMSTER

The pineal gland is known to be light sensitive and to be involved in the seasonal reproduction of male golden hamster Mesocricetus auratus. In general, the pineal gland has been demonstrated to be inhibitory to the reproductive system of the male golden hamster. Melatonin is a pineal hormone which can mimic the action of the pineal gland upon the reproductive system. However, the actual site(s) of melatonin action in the hamster has not been demonstrated. In this study a direct effect of melatonin on the release of FSH and LH from superfused hamster pituitary glands was investigated.^ The superfused pituitary glands showed a stable in vitro basal release of FSH and LH for up to 10 hours. The superfused pituitaries demonstrated reproducible responses to repeated pulses of 10('-8) M LHRH, and a dose-dependent response to stimulation with different concentrations of LHRH.^ Melatonin inhibited the basal release of FSH and LH from superfused hamster pituitary glands. This effect of melatonin was specific and not a general indolamine or catecholamine effect.^ The superfused pituitaries had a diurnal differential responsiveness to physiological concentrations of melatonin with respect to FSH and LH release which were related to the light cycle used to maintain the experimental animals. A LD 14:10 photoperiod cycle was used with light on from 5 a.m. till 7 p.m.. With pituitary glands obtained at 8:30 a.m., the basal release of FSH exhibited an initial inhibition, a gradual rebound at approximately two hours after the beginning of melatonin superfusion, and a significant overshoot of FSH release after the cessation of infusion with melatonin (Morning Response). If the pituitary glands were obtained from hamsters which were sacrificed at 3:30 p.m., the release rate of FSH exhibited an inhibition during the entire period of melatonin infusion with a rebound effect appearing only after melatonin infusion was discontinued (Afternoon Response). There was no significant difference in the responsiveness of the pituitary gland to infusion with melatonin at either 8:30 a.m. or 3:30 p.m. with respect to LH release. Also, melatonin could not inhibit the gonadotropins response to continuous superfusion with 10('-9) M LHRH in pituitaries obtained at either 8:30 a.m. or 3:30 p.m., nor inhibit the stimulatory effect of pulsatile 10('-9) M LHRH. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of author.) UMI^

Sexual orientation and sexual behavior patterns: Evaluation of agreement and variation in a cohort of male, African American drug users in Houston, TX

Background. Sexual orientation and sexual behavior among men have shown disagreement in past studies. The term "on the down low" has been adopted by many to describe "straight" identifying men who have sex with men but do not inform their primary female partner. Methods. This secondary analysis of data collected from the "DASH Project---A Hepatitis B Vaccine Model for HIV Vaccine Trial in Drug Users," assessed sexual behavior patterns among African American drug-using men over time. Using a screener questionnaire to determine sexual orientation and sexual behavior of the men, the study specifically evaluated "straight" identified men who have sex with women only (MSW) to determine what factors were associated with sexual behavior variation to include men during follow-up. The Fisher's Exact Test was used to evaluate the factors. Results. Variation of sexual behavior was highest among "bisexual" identified men followed by "gay" identified men. Fifteen of the original 593 "straight" and MSW men had sexual behavior variation to include men. In the analysis of "straight" and MSW men with variation in sexual behavior compared to those who did not, living on the streets, greater number of sexual partners, trading sex for drugs, and trading sex for money were associated with sexual behavior variation (all p-values <0.01). Conclusions. The factors were only associated when considering the interview when the variation occurred. The same factors at screening were not predictive of sexual behavior variation in the future. Environmental factors, such as living situation, appear to play a role in sexual behavior variations in "straight" and MSW men. ^ Keywords. sexual behavior, sexual orientation, Fisher's Exact Test^

The effect of African Americans' ethnographic paradigms and cultural explanatory model of breast cancer in framing the male partner's attitudes and behaviors about the woman's breast cancer diagnosis

The disparate burden of breast cancer-related morbidity and mortality experienced by African American women compared with women of other races is a topic of intense debate in the medical and public health arenas. The anomaly is consistently attributed to the fact that at diagnosis, a large proportion of African American women have advanced-stage disease. Extensive research has documented the impacts of cultural factors and of socioeconomic factors in shaping African American women's breast-health practices; however, there is another factor of a more subtle influence that might have some role in establishing these women's vulnerability to this disease: the lack of or perceived lack of partner support. Themes expressed in the research literature reflect that many African American breast cancer patients and survivors consider their male partners as being apathetic and nonsupportive. ^ The purpose of this study was to learn how African American couples' ethnographic paradigms and cultural explanatory model of breast cancer frame the male partners' responses to the women's diagnosis and to assess his ability to cope and willingness to adapt to the subsequent challenges. The goal of the study was to determine whether these men's coping and adaptation skills positively or negatively affect the women's self-care attitudes and behaviors. ^ This study involved 4 African American couples in which the woman was a breast cancer survivor. Participants were recruited through a community-based cancer support group and a church-based cancer support group. Recruitment sessions were held at regular meetings of these organizations. Accrual took 2 months. In separate sessions, each male partner and each survivor completed a demographic survey and a questionnaire and were interviewed. Additionally, the couples were asked to participate in a communications activity (Adinkra). This activity was not done to fulfill any part of the study purpose and was not included in the data analysis; rather, it was done to assess its potential use as an intervention to promote dialogue between African American partners about the experience of breast cancer. ^ The questionnaire was analyzed on the basis of a coding schema and the interview responses were analyzed on the principles of hermeneutic phenomenology. In both cases, the instruments were used to determine whether the partner's coping skills reflected a compassionate attitude (positive response) versus an apathetic attitude (negative response) and whether his adaptation skills reflected supportive behaviors (the positive response) versus nonsupportive behaviors (the negative response). Overall, the women's responses showed that they perceived of their partners as being compassionate, yet nonsupportive, and the partner's perceived of themselves likewise. Only half of the women said that their partners' coping and adaptation abilities enabled them to relinquish traditional concepts of control and focus on their own well-being. ^ The themes that emerged indicate that African American men's attitudes and behaviors regarding his female partner's diagnosis of breast cancer and his ability to cope and willingness to adapt are influenced by their ritualistic mantras, folk beliefs, religious teachings/spiritual values, existential ideologies, socioeconomic status, and environmental factors and by their established perceptions of what causes breast cancer, what the treatments and outcomes are, and how the disease affects the entire family, particularly him. These findings imply that a culturally specific intervention might be useful in educating African American men about breast cancer and their roles in supporting their female partners, physically and psychologically, during diagnosis, treatment, and recovery. ^

Hypogonadism in male cancer patients: A cross-sectional study

Introduction. Cancer is the second most common cause of death in the USA (2). Studies have shown a coexistence of cancer and hypogonadism (9,31,13). The majority of patients with cancer develop cachexia, which cannot be solely explained by anorexia seen in these patients. Testosterone is a male sex hormone which is known to increase muscle mass and strength, maintain cancellous bone mass, and increase cortical bone mass, in addition to improving libido, sexual desire, and fantasy (14). If a high prevalence of hypogonadism is detected in male cancer patients, and a significant difference exists in testosterone levels in cancer patients with cachexia versus those without cachexia, testosterone may be administered in future randomized trials to help alleviate cachexia. Study group and design The study group consisted of male cancer patients and non-cancer controls aged between 40 and 70 years. The primary study design was cross-sectional with a sample size of 135. The present data analysis is done on a subset convenience sample of 72 patients recruited between November 2006 and January 2010. ^ Methods. Patients aged 40-70 years with or without a diagnosis of cancer were recruited into the study. All patients with a BMI over 35, significant edema, non-melanomatous skin cancer, current alcohol or illicit drug abuse, concomitant usage of medications interfering with gonadal axis, and anabolic agents, patients on tube feeds or parenteral nutrition within 3 months prior to enrollment were excluded from the study. The study was approved by the Institutional Review Board of Baylor College of Medicine and is being conducted at the Michael E. DeBakey Veterans Affairs Medical Center at Houston. My thesis is a pilot data analysis that employs a smaller subset convenience sample of 72 patients determined by using the data available for the 72 patients (of the intended sample of 135 patients) recruited between November 2006 and January 2010. The primary aim of this analysis is to compare the proportion of patients with hypogonadism in the male cancer and non-cancer control groups, and to evaluate if a significant difference exists with respect to testosterone levels in male cancer patients with cachexia versus those without cachexia. The procedures of the study relevant to the current data analysis included blood collection to measure levels of testosterone and measurement of body weight to categorize cancer patients into cancer cachexia and cancer non-cachexia sub-groups. ^ Results. After logarithmic transformation of data of cancer and control groups, the unpaired t test with unequal variances was done. The proportion of patients with hypogonadism in the male cancer and non-cancer control groups was 47.5% and 22.7% with a Pearson chi2 statistic of 1.6036 and a p value of 0.205. Comparing the mean calculated Bioavailable testosterone in male cancer patients and non-cancer controls resulted in a t statistic of 21.83 and a p value less than 0.001. When the cancer group alone was taken, the mean free testosterone, calculated bioavailable testosterone and total testosterone levels in the cancer non-cachexia sub-group were 3.93, 5.09, 103.51 respectively and in the cancer cachexia sub-group were 3.58, 4.17, 84.08 respectively. The unpaired t test with equal variances showed that the two sub-groups had p values of 0.2015, 0.1842, and 0.4894 with respect to calculated bioavailable testosterone, free testosterone, and total testosterone respectively. ^ Conclusions. The small sample size of this exploratory study, resulting in a small power, does not allow us to draw definitive conclusions. For the given sub-sample, the proportion of patients with hypogonadism in the cancer group was not significantly different from that of patients with hypogonadism in the control group. Inferences on prevalence of hypogonadism in male cancer patients could not be made in this paper as the sub-sample is small and therefore not representative of the general population. However, there was a statistically significant difference in calculated Bioavailable testosterone levels in male cancer patients versus non-cancer controls. Analysis of cachectic and non-cachectic patients within the male cancer group showed no significant difference in testosterone levels (total, free, and calculated bioavailable testosterone) between both sub-groups. However, to re-iterate, this study is exploratory and the results may change once the complete dataset is obtained and analyzed. It however serves as a good template to guide further research and analysis.^

Factors associated with needle sharing among Black male injection drug users in Harris County, Texas

Background. Injection drug users (IDUs) are at increased risk for HIV transmission due to unique risk behaviors, such as sharing needles. In Houston, IDUs account for 18% of all HIV/AIDS cases among Black males. ^ Objectives. This analysis compared demographic, behavioral, and psychosocial characteristics of needle sharing and non-sharing IDUs in a population of Black males in Harris County, Texas. ^ Methods. Data used for this analysis were from the second IDU cycle of the National HIV Behavioral Surveillance System. This dataset included a sample of 288 Black male IDUs. Univariate and multivariate statistical analysis were performed to determine statistically significant associations of needle sharing in this population and to create a functional model to inform local HIV prevention programs. ^ Results. Half of the participants in this analysis shared needles in the past 12 months. Compared to non-sharers, sharers were more likely to be homeless (OR=3.70, p<0.01) or arrested in the past year (OR=2.31, p<0.01), inject cocaine (OR=2.07, p<0.01), report male-to-male sex in the past year (OR=6.97, p<0.01), and to exchange sex for money or drugs. Sharers were less likely than non-sharers to graduate high school (OR=0.36, p<0.01), earn $5,000 or more a year (OR=1.15, p=0.05), get needles from a medical source (OR=0.59, p=0.03), and ever test for HIV (OR=0.17, p<0.01). Sharers were more likely to report depressive symptoms (OR=3.49, p<0.01), lower scores on the family support scale (mean difference 0.41, p=0.01) and decision-making confidence scale (mean difference 0.38, p<0.01), and greater risk-taking (mean difference -0.49, p<0.01) than non-sharers. In a multivariable logistic regression, sharers were less likely to have graduated high school (OR=0.33, p<0.01) and have been tested for HIV (OR=0.12, p<0.01) and were more likely to have been arrested in the past year (OR=2.3, p<0.01), get needles from a street source (OR=3.87, p<0.01), report male-to-male sex (OR=7.01, p<0.01), and have depressive symptoms (OR=2.36, p=0.02) and increased risk-taking (OR=1.78, p=0.01). ^ Conclusions. IDUs that shared needles are different from those that did not, reporting lower socioeconomic status, increased sexual and risk behaviors, increased depressive symptoms and increased risk-taking. These findings suggest that intervention programs that also address these demographic, behavioral, and psychosocial factors may be more successful in decreasing needle sharing among this population.^

LUNG CANCER AMONG TEXAS MALE OIL REFINERY WORKERS, 1976 - 1980 (CASE-CONTROL STUDY)

The apparent excess in the rate of lung cancer among the population of Texas coastal counties has prompted this study. The main objective was to assess the risk of lung cancer among employees of oil refining industries. Data collected by UTSPH and NCI were used for this research. A non significant overall low risk of lung cancer was observed among workers ever employed in oil refining (COR = 0.84). A lower but not significant risk of lung cancer was detected among the same workers when classified by their usual industry of employment (COR = 0.77). An overall non significant crosstime decline in the risk of lung cancer was observed among most of the occupational groups within the oil refining industry, with the exception of professional/technical and clerical/sales occupations where a non significant crosstime increase in the risk was observed. ^

GENETIC INTERACTIONS OF FACTORS THAT REGULATE ALTERNATIVE RNA SPLICING IN THE MALE GERM LINE OF DROSOPHILA

Alternative RNA splicing is a critical process that contributes variety to protein functions, and further controls cell differentiation and normal development. Although it is known that most eukaryotic genes produce multiple transcripts in which splice site selection is regulated, how RNA binding proteins cooperate to activate and repress specific splice sites is still poorly understood. In addition how the regulation of alternative splicing affects germ cell development is also not well known. In this study, Drosophila Transformer 2 (Tra2) was used as a model to explore both the mechanism of its repressive function on its own pre-mRNA splicing, and the effect of the splicing regulation on spermatogenesis in testis. Half-pint (Hfp), a protein known as splicing activator, was identified in an S2 cell-based RNAi screen as a co-repressor that functions in combination with Tra2 in the splicing repression of the M1 intron. Its repressive splicing function is found to be sequence specific and is dependent on both the weak 3’ splice site and an intronic splicing silencer within the M1 intron. In addition we found that in vivo, two forms of Hfp are expressed in a cell type specific manner. These alternative forms differ at their amino terminus affecting the presence of a region with four RS dipeptides. Using assays in Drosophila S2 cells, we determined that the alternative N terminal domain is necessary in repression. This difference is probably due to differential localization of the two isoforms in the nucleus and cytoplasm. Our in vivo studies show that both Hfp and Tra2 are required for normal spermatogenesis and cooperate in repression of M1 splicing in spermatocytes. But interestingly, Tra2 and Hfp antagonize each other’s function in regulating germline specific alternative splicing of Taf1 (TBP associated factor 1). Genetic and cytological studies showed that mutants of Hfp and Taf1 both cause similar defects in meiosis and spermatogenesis. These results suggest Hfp regulates normal spermatogenesis partially through the regulation of taf1 splicing. These observations indicate that Hfp regulates tra2 and taf1 activity and play an important role in germ cell differentiation of male flies.

A comparison of health behaviors of African -American male and female illicit drug users: Implications for community health practice

Prevalence of drug use, HIV, syphilis, and other STDs is particularly high in African-American populations. Although some studies have documented protective changes in health behaviors relevant to these outcomes, other research indicates that risky health behaviors are still widespread. Moreover, little is known about how African-American men and women have differed in their responses to calls to adopt protective behaviors. The study reported in this dissertation investigates gender differences in health risk behavior in a sample of 482 African American chronic, frequent injection drug and crack cocaine users residing in Houston, Texas. It uses baseline and 9 month follow-up data collected on this sample. Four major research questions are addressed. These questions are: Research question 1. What was the overall pattern of reduction in drug use for subjects in the sample? In particular, did subjects who reported a recent (30 day) reduction in drug use and needle sharing risk at baseline also report a reduction at follow-up? Research question 2. Is gender significantly associated with the overall pattern of risk reduction in drug injection observed in the two waves of the study? Research question 3. Is gender significantly associated with the overall pattern of reduction in the number of sexual partners observed in the two waves of the study? Research question 4. Is gender significantly associated with the overall pattern of increase in the use of barrier contraceptives in the two waves of the study? ^