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Biomedical subjects

C S Alexander

Publications and source records attributed to C S Alexander.

At least 19 recordsLinked to original sources
PubMed2002

Sensitivity to disorder of the metallic state in the ruthenates.

We report the results of transport measurements on SrRuO3, Sr3Ru2O7, and CaRuO3. In SrRuO3 and Sr3Ru2O7, our findings are consistent with the predictions of Fermi liquid theory, in contrast to previous reports based on samples with much shorter mean free paths. In CaRuO3, however, a T1.5 power law is seen in the resistivity in the high purity samples studied here. Our work gives concrete evidence that even the metallic state of the ruthenates is highly sensitive to disorder.

Journal Article↗
PubMed2001

Management of common symptoms in terminally ill patients: Part II. Constipation, delirium and dyspnea.

In addition to pain, patients who are approaching the end of life commonly have other symptoms. Unless contraindicated, prophylaxis with a gastrointestinal motility stimulant laxative and a stool softener is appropriate in terminally ill patients who are being given opioids. Patients with low performance status are not candidates for surgical treatment of bowel obstruction. Cramping abdominal pain associated with mechanical bowel obstruction often can be managed with morphine (titrating the dosage for pain) and octreotide. Delirium is common at the end of life and is frequently caused by a combination of medications, dehydration, infections or hypoxia. Haloperidol is the pharmaceutical agent of choice for the management of delirium. Dyspnea, the subjective sensation of uncomfortable breathing, is often treated by titration of an opioid to relieve the symptom; a benzodiazepine is used when anxiety is a component of the breathlessness.

Analgesics, Opioid↗
PubMed2001

Management of common symptoms in terminally ill patients: Part I. Fatigue, anorexia, cachexia, nausea and vomiting.

Physical symptoms other than pain often contribute to suffering near the end of life. In addition to pain, the most common symptoms in the terminal stages of an illness such as cancer or acquired immunodeficiency syndrome are fatigue, anorexia, cachexia, nausea, vomiting, constipation, delirium and dyspnea. Management involves a diagnostic evaluation for the cause of each symptom when possible, treatment of the identified cause when reasonable, and concomitant treatment of the symptom using nonpharmacologic and adjunctive pharmacologic measures. Part I of this two-part article discusses fatigue, anorexia, cachexia, nausea and vomiting. Fatigue is the most common symptom at the end of life, but little is known about its pathophysiology and specific treatment. Education of the patient and family is the foundation of treatment with the possible use of adjunctive psychostimulants. Anorexia and cachexia caused by wasting syndromes are best managed with patient and family education, as well as a possible trial of appetite stimulants such as megestrol or dexamethasone. For appropriate pharmacologic treatment, it is helpful to identify the pathophysiologic origin of nausea in each patient.

Anorexia↗
PubMed2001

HIV protease and reverse transcriptase variation and therapy outcome in antiretroviral-naive individuals from a large North American cohort.

OBJECTIVE: To assess the effect of baseline HIV reverse transcriptase (RT) and protease sequence variation on virologic outcomes in a large cohort of antiretroviral-naive patients in British Columbia, Canada. METHODS: Population sequencing of RT and protease was performed on baseline viral RNA of all antiretroviral-naive patients first seeking treatment in British Columbia between June 1997 and August 1998 (n = 479). Relative risks of virological failure associated with genotypic differences from a 'standard' HIV strain (HXB2) were assessed for up to 18 months. RESULTS: The prevalence of key baseline mutations known to confer resistance to RT and protease inhibitors (PI) was 3.4 and 3.8%, respectively. No statistically significant impact on virologic outcomes could be established for these patients. However, the data suggest that some individuals (harboring a M184V mutation in RT or a V82I in protease) may have benefited from pre-therapy resistance tests. 'Secondary' mutations in the protease associated with resistance (e.g. codons 10, 36 or 63) were common, but the presence of these secondary mutations, either alone or in combination, did not appear to result in early loss of therapeutic virological suppression. Preliminary analyses suggest that an amino acid change at codon 35 in the protease may be associated with early treatment failure. CONCLUSIONS: The results suggest that routine genotyping of naive patients about to start antiretroviral therapy would be of benefit to a relatively small proportion of the population. Secondary mutations associated with resistance to PI alone were not found to affect virologic outcomes significantly.

Anti-HIV Agents↗
PubMed2000

Human immunodeficiency virus-infected persons with mutations conferring resistance to zidovudine show reduced virologic responses to hydroxyurea and stavudine-lamivudine.

The baseline predictors of poor virologic response (<0.5 log decrease in plasma virus load) were examined in two 1996 pilot trials of combination nucleoside-analogue therapy. One trial examined the addition of hydroxyurea to didanosine therapy; the other examined stavudine-lamivudine in combination. In both, predictors of virologic response included the presence of mutations associated with zidovudine resistance. For hydroxyurea, the odds ratio (OR) of failure to achieve a short-term (4 weeks) virologic response in a bivariate logistic regression model was 30.8 (95% confidence interval [CI], 1.75-543; P=.02) for use of lower dose hydroxyurea (500 mg/day) and 14.7 (95% CI, 1.1-200; P=.04) for the presence of a zidovudine-related mutation. For the stavudine-lamivudine study, the OR of failure to achieve a virologic response at 4 weeks in a multivariate logistic regression model was 23 (95% CI, 2.7-199; P=.004) for the presence of a mutation at codon 215.

Anti-HIV Agents↗
PubMed1999

Prevalence of primary HIV drug resistance among seroconverters during an explosive outbreak of HIV infection among injecting drug users.

OBJECTIVES: This study examined the frequency of transmission of drug resistant HIV in the population of injecting drug users (IDU) in Vancouver, Canada during a period of particularly high virus transmission. DESIGN: All subjects enrolled in the Vancouver Injection Drug Users Study who seroconverted from HIV negative to positive status (n = 61) between December 1996 and February 1998 were eligible for analysis. The first seropositive sample from 57 individuals with plasma samples available was analyzed for resistance to antiretroviral agents by population based sequencing of the HIV protease and reverse transcriptase genes. METHODS: Plasma viral RNA was extracted and the viral reverse transcriptase and protease regions were amplified by nested reverse transcription-PCR. The presence of mutations associated with antiretroviral drug resistance was assessed by automated sequence analysis. RESULTS: Protease and reverse transcriptase sequences were successfully obtained from the 57 recent seroconverters. No cases of transmission of variants associated with significant resistance to protease inhibitors or nucleoside and non-nucleosides reverse transcriptase inhibitors were detected. CONCLUSION: The frequency of transmission of drug resistant HIV amongst these recently infected IDU is extremely low, with no protease or reverse transcriptase inhibitor resistant strains detected soon after seroconversion. The data provide no rationale for withholding treatment from this already marginalized population.

Anti-HIV Agents↗
PubMed1999

Selection of drug-resistant HIV.

Resistance to antiretroviral drugs by HIV develops from competition among several different virus variants within an individual. Recent studies have measured the changing proportions of HIV populations, which differ by single nucleic acids, under the selective pressures exerted by the addition or removal of antiretroviral drugs.

Animals↗
PubMed1999

Determinants of condom use to prevent HIV infection among youth in Ghana.

PURPOSE: To identify the psychosocial and behavioral factors that influence condom use to reduce the risk of human immunodeficiency virus (HIV) infection among young men in Ghana. METHODS: This study used a cross-sectional design in which data on a community-based sample of 601 young men, 15-24 years of age, were collected by a household survey instrument. For a conceptual framework, the study used constructs from the Health Belief Model (HBM) and Social Learning Theory (SLT) in the Ghanaian context. RESULTS: While 65% of the sexually active male respondents had used condoms at least once, only 25% had used condoms at last intercourse. Findings from multiple logistic regression analysis indicate that perceived susceptibility to HIV infection, perceived self-efficacy to use condoms, perceived barriers to condom use, and perceived social support were significant predictors of condom use. The most important finding, however, is that perceived barriers significantly interacted with perceived susceptibility and self-efficacy. Subjects who perceived a high level of susceptibility to HIV infection and a low level of barriers to condom use were almost six times as likely to have used condoms at last intercourse, compared to others. Similarly, young men who perceived a high level of self-efficacy to use condoms and a low level of barriers to condom use were nearly three times more likely to have used condoms at last intercourse when compared to others. CONCLUSION: These results suggest that HIV prevention programs for youth should emphasize personal vulnerability to acquired immunodeficiency syndrome, instill in youth the self-belief that they can use condoms any time, and address how to overcome barriers to condom use.

Adolescent↗
PubMed1999

Trauma-related hospitalizations among urban adolescents in New Zealand: priorities for prevention.

PURPOSE: To: (a) determine the magnitude, characteristics, and in-patient costs of injury among hospitalized urban adolescents in New Zealand (NZ); (b) identify regional priorities for injury prevention and investigative research; and (c) compare the study findings with published data from other industrialized countries. METHODS: The 1989-1993 files of the NZ Hospital Discharge Database were accessed to identify and analyze trauma-related admissions of adolescents residing in NZ's largest metropolitan region. RESULTS: The estimated 9569 hospitalizations for injury accounted for one-fourth of all adolescent admissions in the region, a mean annual hospitalization rate of 1292/100,000 population and a minimum annual cost of NZ $5.8 million for in-patient care. Males and indigenous Maori youth had comparatively higher rates of hospitalizations for most major causes of injury. Falls, pedal cyclist injury, cuts, and piercing injuries were leading causes of hospitalization for trauma in early adolescence. Admission rates for motorcylist and other motor vehicle occupant trauma and self-inflicted injury increased substantially among older adolescents. Sport and recreational activities comprised at least one-sixth of injury admissions. CONCLUSIONS: The overall rates of injury resulting in hospitalization among Auckland adolescents were comparable to those reported from Australia and France, but higher than those from the United States, Canada, and Israel. By identifying priority issues and high-risk groups, this study provides a foundation for regional injury control initiatives. It also demonstrates the utility and limitations of E-coded hospital discharge registries in defining the burden of serious nonfatal trauma.

Adolescent↗
PubMed1999

Taking a first puff: cigarette smoking experiences among ethnically diverse adolescents.

OBJECTIVES: To study the social contexts and physiological consequences of an initial cigarette smoking experience among adolescents from four ethnic groups (African American, European American, Hispanic, Native American) who vary by gender and locale (e.g. urban vs rural). METHOD: A qualitative study using individual interviews and focus groups. RESULTS: Results both amplify and reinforce conclusions about peer and family influences on adolescent smoking initiation reported in quantitative studies of teen smoking. Within the broader themes of peers and family, several important sub-themes emerged. The study findings suggest that peer influence can be characterized as social conformity or social acceptance. Males were more likely than females to describe experiences involving peers exerting strong messages to conform to smoking behaviors. Roles played by family members in the initiation process were complex and included those of initiator, prompter, accomplice, and inadvertent source of cigarettes. European American and Hispanic girls provided descriptions of parents/family members as instigators of their first smoking experience. Hispanic adolescents descripted instances in which family members prompted cigarette use at a young age by encouraging the young person to light the adult's cigarette. Finally, ethnic differences in the physiological responses to initial smoking suggest the need to further explore the role of brand preference and variations in inhaling among ethnically diverse adolescents. CONCLUSION: In order to design effective cigarette smoking prevention programs for adolescents, it is important to understand the meaning of smoking behaviors for adolescents from different ethnic and social backgrounds.

Adolescent↗
PubMed1997

Palliative medicine and HIV/AIDS.

This article provides an introduction to the field of palliative medicine as it applies to the care of HIV/AIDS. Issues of pain management, end-of-life care, ethics, and bereavement are discussed with the intention of providing the primary care physician additional resources in the provision of care to patients with HIV/AIDS.

Bereavement↗
PubMed1995

Gender differences in injuries among rural youth.

GOAL: This paper presents injury data from the first year of a three year longitudinal study of risk taking behaviors among adolescents. SAMPLE: Study subjects were a cohort of 758 rural students from Maryland's Eastern Shore who were in the eighth grade in 1987. METHODS: Students completed a 45 minute, self administered survey in which they reported numbers of injuries experienced in the past year, risk taking behaviors, anger expression, delinquency, alcohol and drug use, physical exercise, work experience, and level of parental supervision. In addition, students had their height and weight measurements taken by trained research staff and completed a self rating of pubertal development using Tanner drawings. RESULTS: Slightly more than half (53.2%) of the boys and over one third (37.7%) of the girls reported experiencing one or more medically attended injuries during the last year. Poisson regression analyses were conducted to estimate the extent to which gender differences in injuries could be accounted for by adolescent behaviors. Gender effects became non-significant when adjustments were made for risk taking, school discipline problems, and exercise frequency. Gender differences in injuries were reduced but remained significant when substance use, employment, and anger were controlled. Poisson regression analyses were conducted separately for males and females to assess whether factors associated with injuries were similar across genders. For boys, risk taking, anger, and school discipline problems were significantly related to number of injuries. Boys with a low body mass index and late pubertal development (mean ratio 3.09), as well as those with high body mass index and early pubertal development (mean ratio 2.16), reported greater numbers of injuries than average boys. For girls, substance use, cruising, risk taking, anger, and exercise frequency were significantly associated with injuries. Girls with an early onset of menses reported, on average, twice the number of injuries than those who were on time. Girls with high body mass index who were late in their pubertal development reported, on average, five times more injuries than other girls. CONCLUSIONS: Although gender is a significant risk factor for injuries, certain behaviors like risk taking, school related delinquency, and physical exercise partially explain the higher number of injuries among adolescent males in this study. For both males and females, indicators of pubertal and physical development are important factors to consider in studies of injuries during early adolescence.

Adolescent↗
PubMed1992

Behavioral risk factors for injury among rural adolescents.

This 3-year, longitudinal, prospective study examined behavioral risk factors for medically attended injuries among a cohort of 758 rural students from Maryland's Eastern Shore region who were 12-14 years of age in 1987. Students were surveyed annually in the eighth, ninth, and tenth grades with a self-administered questionnaire. Information was obtained on the number of injuries experienced, risk-taking behaviors, delinquency, alcohol and drug use, physical exercise and sports, parental supervision, and work experience. Information on the parents' education was obtained from a parental interview. Slightly more than half (53.5%) of the students reported having experienced one or more injuries in the eighth grade as compared with one-third of the students in ninth grade, and 38% of those in the tenth grade. Poisson regression analyses were conducted to examine the association of eighth grade variables with ninth grade injuries and ninth grade variables with tenth grade injuries. Results from these analyses indicated that, in addition to sex and race, a high degree of risk taking, frequent cruising, and having high and low parental supervision in the eighth grade significantly increased the number of injuries in ninth grade. In the tenth grade, risk taking continued to be associated with injuries. In addition, students who reported disciplinary problems in school, working 1-10 hours per week, drinking on 1-2 days during the past month, lifetime use of marijuana equal to 1-5 occasions, and involvement in sports experienced greater numbers of injuries in the tenth grade.

Adolescent↗
PubMed1991

Maternal satisfaction with primary care for children with selected chronic conditions.

One hundred forty mothers of children with chronic illnesses seen in two pediatric specialty clinics of a major urban teaching hospital were surveyed regarding their primary care arrangements and satisfaction with care received. Three dimensions of maternal satisfaction were measured: general satisfaction, satisfaction with access to care and satisfaction with doctor conduct (physician humaneness and technical quality). Results of multivariate analyses indicate that receipt of anticipatory guidance, access to care during evening hours and having a child in excellent reported health status were significantly associated with at least two of the three dimensions of maternal satisfaction. Findings have implications for organizing comprehensive, accessible primary care in the community, which is consistent with recent trends in child health policy. Results supported the need for enrichment of primary care for children with chronic illnesses to allow for physician continuity, provision of information and advice to families and extended office hours.

Baltimore↗
PubMed1990

Acute gastrointestinal illness and child care arrangements.

This study uses data from the 1981 National Health Interview and the 1981 Child Health Supplement to assess the extent to which family day care homes and child care centers pose a risk of acute gastrointestinal illness among preschool children. The study uses a nationally representative sample of children 0-5 years of age (n = 4,845). Acute gastrointestinal illness was identified from parental reports of acute illness in a 2-week period. Information on type and duration of child care, as well as a variety of sociodemographic and environmental factors (e.g., crowding, seasonality), were obtained. The authors hypothesize that risk of acute gastrointestinal illness would vary by group size. Center attendees were thought to have the greatest exposure to infectious agents, followed by children in day care homes, and lastly by those receiving care in their own homes. Risk models were estimated separately for children less than 3 years of age and for children aged 3-5 years. Our results show that an elevated risk of acute gastrointestinal illness associated with child care is confined to children less than 3 years of age who regularly attend centers/nursery schools (odds ratio = 3.49, 95% confidence interval 0.99-4.77), controlling for other confounding variables. For children aged 3-5 years, low socioeconomic status, poverty, and seasonality are stronger predictors of acute gastrointestinal illness than is center care. Family day care appears to be unrelated to the risk of illness for both age groups.

Acute Disease↗
PubMed1990

[Etiology and occurrence of periodic eye inflammation of horses in the area of Berlin].

Over 130 cases of equine periodic ophthalmia (p.o.), which were treated as in-patients at the Equine Clinic of the Free University of Berlin in the last 35 years, were examined statistically in relation to the age and gender of the animals involved as well as to the development of the illness and the season in which it arose. As regards aetiology, the extraction of 71 affected Trotters was investigated. Antibodies to toxoplasmosis, leptospirosis and intestinal parasites were found only in some of the patients. Younger animals, aged between one and four years, and male animals (63.6%) were predominantly affected. The results of the examinations of faeces showed no correlation between cases of p.o. and a vermination of the horses. The examinations for antibodies to toxoplasmosis gave no indication of a participation of the toxoplasmas in the aetiology of recurrent uveitis. In contrast, the results of the examinations for antibodies to leptospirosis, of which 58.8% were positive, showed a seven to ten times higher infection than in healthy horses in Berlin. Breed analysis showed that in certain breeds of Trotters and warm-blooded horses, p.o. illnesses were frequent, supporting the hypothesis that the occurrence of p.o. is due to a hereditary, allergic reaction, triggered by various factors, in particular an infection without clinical signs.

Age Factors↗
PubMed1989

Social network structure and prenatal care utilization.

The associations between social network structural characteristics, sociodemographic factors, and prenatal care utilization were examined in a sample of 185 low-income, inner-city, maternity patients. It was predicted that the networks of women who underutilized care would be larger and of higher density than those of women who utilized care appropriately. They were also expected to be less disperse, with members living near one another; less diverse, with members drawn mainly from immediate family and extended kin; and composed primarily of strong relational ties between members. Findings indicated that women were more likely to underutilize care if they were embedded in strong-tie, nondisperse networks where most members were immediate family or relatives. Of the sociodemographic variables, only parity was associated with prenatal care utilization. The findings support the underlying assumption that social networks have a significant influence on individuals' utilization of prenatal services. This suggests that providers of services to pregnant women may need to revise their current strategies for bringing women into care and their methods of delivering educational services to women already in care.

Adult↗