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Biomedical subjects

R C Chung

Publications and source records attributed to R C Chung.

At least 19 recordsLinked to original sources
PubMed2003

Is there an epidemic of HIV/AIDS among heterosexuals in the USA?

The Centers for Disease Control and Prevention (CDC), Atlanta, reports HIV infections and AIDS cases in the United States biannually. Trends in the distribution of HIV/AIDS cases according to sex, race or ethnic group, and various categories of exposure to HIV were analysed. The groups in which there were the greatest percentage increases over time were the group with heterosexual contact and the group for whom the risk factors were not reported or identified. The CDC should be encouraged to provide additional information regarding sexual and drug-using behaviours of those patients listed as "undetermined".

Acquired Immunodeficiency Syndrome↗
PubMed1998

Size and duration of zidovudine benefit in 1003 HIV-infected patients: U.S. Army, Navy, and Air Force natural history data. Military Medical Consortium for Applied Retroviral Research.

OBJECTIVES: The study's objectives were to determine the size and duration of benefits of early versus delayed versus late treatment with zidovudine (ZDV) on disease progression and mortality in HIV-infected patients, and whether patients rapidly progressing before ZDV treatment had a different outcome from those not rapidly progressing before ZDV. DESIGN: The design was an inception cohort of 1003 HIV-infected patients. One hundred and seventy-four of the 1003 patients were treated before CD4 counts fell to <400 x 10(9)/L, ("early treatment"); 183 of 1003 patients were treated after CD4 counts fell to <400 x 10(9)/L but before clinical disease developed ("delayed treatment"); and 646 of the 1003 patients had either been treated after clinical disease developed or had not been treated at all by the end of follow-up ("late treatment"). Outcomes were progression to clinical HIV disease and mortality. RESULTS: The relative risk (RR) of progression for early versus delayed treatment was 0.58 (p < .03), and durability of ZDV benefits on progression was estimated at no more than 2.0 years; however, this estimate had wide confidence intervals. The RR of progression for delayed versus late treatment was 0.54 p < .0001, and durability of ZDV benefits was estimated at 1.74 years; this estimate had narrow confidence intervals. Survival was better for the early versus delayed treatment (RR = 0.55), but this difference was not statistically significant. In the subgroup of patients with more rapid CD4 decline prior to ZDV therapy, significant benefits on progression were observed for early versus delayed ZDV therapy (RR = 0.42, p = .02) and delayed versus late ZDV therapy (RR = 0.51; p = .0004). Duration of benefit was estimated to be 4.5 years (early versus delayed) and 1.7 years (delayed versus late). For patients with less rapid pre-ZDV decline in CD4 levels, a significant progression benefit was observed for delayed versus late therapy (RR = 0.50; p = .02). Duration of benefit in this subgroup was estimated to be 1.8 years. No significant benefit was found for early versus delayed treatment (RR = 1.12) in the less rapid pre-ZDV CD4 cell decline subgroup. CONCLUSIONS: Early treatment compared with delayed treatment was associated with a sizable reduction in HIV progression, but the duration of benefits was estimated to last only about 2 years. Delayed treatment compared with late treatment with ZDV was associated with substantial reduction of progression, but this reduction was also clearly limited in duration. Benefits on progression and mortality for the early treatment group were heavily dependent on the pre-ZDV CD4 slope. In the subgroup of patients with the most rapid pre-ZDV CD4 cell declines, the duration of benefit was much longer, possibly as long as 4 years.

Adult↗
PubMed1998

Gender differences in psychological distress among Southeast Asian refugees.

The focus of this study was to examine gender differences in levels and predictors of psychological distress in a community sample of Southeast Asian refugees. Although previous studies with clinical samples of Southeast Asian refugees have found gender differences in the degree of psychological distress, the few community-based studies have been inconclusive. This community study found that there were gender differences in the predictors of distress and that refugee women reported significantly higher levels of psychological distress than their male counterparts. Implications of the findings are discussed.

Adaptation, Psychological↗
PubMed1998

Lifetime and twelve-month prevalence rates of major depressive episodes and dysthymia among Chinese Americans in Los Angeles.

OBJECTIVE: The authors' goal was to estimate the lifetime and 12-month rates of major depressive episodes and dysthymia for Chinese Americans who reside in Los Angeles. This effort, the Chinese American Psychiatric Epidemiological Study, is the first large-scale community psychiatric epidemiological study on an Asian American ethnic group that used DSM-III-R criteria for major depressive episodes and dysthymia. METHOD: A multi-stage sampling design was used to select respondents for participation in the survey. The sample included 1,747 adults, 18-65 years of age, who resided in Los Angeles County and who spoke English, Mandarin, or Cantonese. RESULTS: Approximately 6.9% of the respondents had experienced an episode of major depression and 5.2% had had dysthymia in their lifetime. The 12-month rates of depressive episode and dysthymia were 3.4% and 0.9%, respectively. The most consistent correlate of lifetime and 12-month depressive episode and dysthymia was social stress, measured by past traumatic events and recent negative life events. CONCLUSIONS: The Chinese American Psychiatric Epidemiological Study provides a rare opportunity to investigate the heterogeneity within a single Asian American ethnic group, Chinese Americans, and to identify the subgroups among Chinese Americans who may be most at risk for mental health problems.

Acculturation↗
PubMed1998

Health insurance coverage among Chinese Americans in Los Angeles County.

OBJECTIVES: This paper examines the factors associated with health insurance coverage among Chinese Americans in Los Angeles County. METHODS: Data were obtained through interviews conducted in 1993 and 1994 with Chinese Americans (aged 18 through 65 years) residing in Los Angeles County. A multistage probability sample was used to select respondents. RESULTS: The final sample consisted of 1747 respondents, which represented an 82% response rate. Thirty-nine percent of the respondents in the survey were without health insurance at the time of the survey. CONCLUSIONS: Logistic regression analysis showed that marital status, length of residence in the United States, education, employment, and household income were associated with health insurance coverage among Chinese Americans.

Adolescent↗
PubMed1997

Evolution of human immunodeficiency virus type 1 env sequence variation in patients with diverse rates of disease progression and T-cell function.

We examined the relationship between env sequence variation and disease progression in 10 human immunodeficiency virus type 1 (HIV-1)-seropositive subjects selected from a longitudinal cohort receiving zidovudine therapy. Five subjects were chosen for stable clinical status and CD4 counts (slow progressors), and five were selected for rapid clinical deterioration and CD4 count decline (rapid progressors). The slow progressors had significantly lower plasma viral RNA loads and greater lymphoproliferative responses to mitogens than the rapid progressors. DNA sequences representing the C1 through C3 regions of env were amplified from two peripheral blood mononuclear cell DNA samples from each subject separated by an average of 2.5 years. Molecular clones of these amplicons were then sequenced, and DNA sequence and deduced amino acid sequence distances were compared. Inter-time point sequence comparison showed a higher rate of sequence evolution for the rapid progressors in three of five matched pairs of rapid progressors and slow progressors and for the slow progressors in the remaining two subject pairs. However, intra-time point sequence comparisons showed that four of five slow progressors developed a more diverse quasispecies over time and one showed no change. In contrast, four of five rapid progressors showed no change in quasispecies diversity over time and one showed a significant decrease in diversity. The overall C1 through C3 region quasispecies diversity in the slow progressors at baseline was lower than that for the rapid progressors, but this difference was not significant at the follow-up time points. These diversity relationships were obscured if sequence analyses were limited to the 300-bp C2 to V3 region. Thus, HIV-1 quasispecies diversity increased over time in subjects with more functional immune systems.

Base Sequence↗
PubMed1996

The effects of welfare status on psychological distress among Southeast Asian refugees.

It has been established in the general population that there is a relationship between welfare status and psychological well-being. There are few studies, however, which investigate the effects of welfare dependency on Southeast Asian refugees, a population that is highly dependent on welfare. This study examined the relationship between welfare status and psychological well-being among Vietnamese, Cambodian, Laotian, and Hmong refugees. The study compared three welfare groups: those who have never been on welfare, those who were once dependent on welfare and are no longer on welfare, and those who are still welfare-dependent. The results supported three hypotheses: a) a high percentage of all four refugee groups were still dependent on welfare even after being in the United States for an average of 5 to 6 years, b) a significant relationship was found between welfare dependency and psychological distress, and c) dependence on welfare had long-term effects for all four groups. An interesting finding that emerged for the Vietnamese, Cambodians, and Laotians was that individuals who were once on welfare but who are no longer receiving welfare benefits are at similar risk as their counterparts who are currently on welfare of developing psychological distress. The findings therefore showed that for this population, if individuals had been touched by welfare at any period in their lives, they were at risk of developing psychological distress. There was an unexpected different finding for the Hmong; individuals who were no longer on welfare were more at risk than those who continued to receive or never had received welfare. Reasons for the intergroup differences and why refugees tended to stay on welfare longer than the general population were explored, along with a discussion about the implications of the findings for refugee policy.

Adolescent↗
PubMed1995

Isolated peripheral tuberculous lymphadenitis in adults: current clinical and diagnostic issues.

Eight cases of isolated peripheral tuberculous lymphadenitis occurred over a 16-month period at our institution, prompting a literature review to establish the epidemiology, clinical manifestations, and current approaches to diagnosis and treatment of this disorder. It occurs most commonly in young adult women who either are immigrants from areas where tuberculous is endemic or have histories of travel that are suggestive of exposure to Mycobacterium tuberculosis. The disease is indolent and usually presents as a unilateral painless neck mass. Constitutional symptoms are rare, except in individuals infected with the human immunodeficiency virus (HIV). The results of skin testing with purified protein derivative are invariably positive. Excisional biopsy for histopathologic and microbiological evaluations provides the highest diagnostic yield, although fine needle aspiration may be useful for HIV-infected individuals and in areas of the world with a high prevalence of disease. A 6-month course of combination antituberculous therapy is adequate for disease due to susceptible organisms. This infection may be readily diagnosed if suggestive epidemiological and clinical findings lead to expeditious tissue sampling.

Adult↗
PubMed1995

Quantitative relationship of circulating p24 antigen with human immunodeficiency virus (HIV) RNA and specific antibody in HIV-infected subjects receiving antiretroviral therapy. The RV43 Study Group.

To better understand the biologic meaning and potential clinical utility of p24 antigen measurements in human immunodeficiency virus (HIV) infection, p24 antigen and antibody and HIV RNA were quantitated in parallel. Specimens (n = 311) were analyzed from 74 participants in a zidovudine treatment study. Parallel antigen and RNA measurements revealed the frequent occurrence of two types of discordant results. First, p24 antigen was often not detected in samples with high antibody levels even when > 10(6) RNA copies/mL were present. Second, in specimens in which p24 antigen was detected, the concentration was greater than expected on the basis of HIV RNA values. These results suggest that optimal use of serum p24 antigen values will require consideration of both specific antibody levels and non-virion associated antigen.

Adult↗
PubMed1995

Interpretation of symptom presentation and distress. A Southeast Asian refugee example.

Symptom expression or the manifestation of distress is greatly influenced by one's cultural background. This exploratory study investigated symptom presentation of distress among a community sample of Vietnamese, Chinese-Vietnamese, Cambodian, and Lao refugees. The study examined whether or not the Western-designed distress measure used in the study was culturally sensitive enough to accurately capture culturally framed expressions of distress. The results of the factor analyses showed that the four Southeast Asian refugee groups did not express distress in three separate factors as devised in the original measure. Instead, a single robust factor emerged. The single factor comprised items from the depression, anxiety, somatic, and psychosocial dysfunction subscales. The items that made up the single factor strongly resemble the construct for the diagnosis of neurasthenia. Researchers have found neurasthenia to be a culturally sanctioned Asian cultural idiom of distress. The findings strongly suggested that this Southeast Asian refugee population expressed distress in a pattern of symptoms more consistent with Asian nosology. The clinical and research implications of the results of this exploratory study are also discussed.

Acculturation↗
PubMed1993

Predictors of psychological distress among southeast Asian refugees.

This paper analyzed data from one of the first needs assessment projects on a representative non-clinical population of Southeast Asian refugees in the United States in order to test two hypotheses: (1) whether or not premigration experiences still have an effect on psychological distress beyond the initial resettlement period and (2) whether or not interethnic group differences existed in the predictors of psychological distress between three Southeast Asian refugee groups, the Vietnamese, Cambodians and Lao. The results of the analysis of 2180 subjects supported both hypotheses. Regardless of ethnicity and the number of years in the U.S., premigration trauma events and refugee camp experiences were significant predictors of psychological distress even 5 years or more after migration and significant group differences in the types of postmigration distress predictors were also found. Acculturation concerns for the Vietnamese and Lao were influenced by both premigration and postmigration variables. In contrast, the primary concerns of the Cambodians were still related to premigration issues. The results also indicated that Vietnamese and Lao women were more likely to experience distress than their male counterparts, but no gender differences emerged for the Cambodians. Age predicted distress for Vietnamese and Cambodians, but not Lao. Similar to previous findings in the literature, Cambodians reported the highest levels of distress, followed by Lao and then Vietnamese. Interpretations of these results for this community sample are proposed.

Adolescent↗
PubMed1992

CD4 lymphocyte decline and survival in human immunodeficiency virus infection. The Military Medical Consortium for Applied Retroviral Research.

The loss of the CD4 lymphocyte is the central pathophysiologic event in the progression of human immunodeficiency virus (HIV) infection. This retrospective study, based on review of data from deceased HIV patients followed in a single HIV clinic, was conducted to determine if the rate of CD4 lymphocyte decline was predictive of survival. Forty of 172 patients met defined criteria for inclusion in this study. For each patient, CD4-cell counts showed approximate exponential decline over time. A Cox regression analysis was used to assess the association of CD4 cell decline (half-life), race, age, gender, initial CD4-cell count, and treatment (anti-Pneumocystis carinii pneumonia prophylaxis and/or zidovudine vs. no therapy) on total survival (from initial CD4 cell count) and on remaining survival time after reaching a CD4 cell count of 100 (estimated). For all patients, the rate of CD4 cell decline was predictive of total survival (p = .009) but not for survival after reaching a count of 100 (p = .6). For patients who had never received therapy (6 patients), however, the CD4 half-life remained associated with survival time from 100 CD4 cells (p < .05) as opposed to the treated patients. Therapy was the single variable most predictive of both survival endpoints, resulting in an increase in median total survival of 27.2 mo (p < .00001) and of 15.4 mo from a CD4 cell count of 100 (p < .00004). Nonwhites had a slight survival disadvantage compared to whites (p = .08 overall; p = .02 from CD4 cell count of 100).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Efficacy trial of a parenteral gonococcal pilus vaccine in men.

A randomized, placebo-controlled, double-blind efficacy trial of a purified gonococcal pilus vaccine composed of a single pilus type was tested in 3123 men and 127 women volunteers. Either 100 micrograms of vaccine or a placebo was given intradermally on day 1 and day 14. Each group was evenly matched with respect to age, sex, prior history of a sexually transmitted disease, sexual exposure during the study and attrition from the study. None of the women volunteers acquired gonorrhoea during the trial. In the male volunteers, 108 vaccine and 102 placebo recipients acquired gonorrhoea 15 days or later after the initial immunization. Vaccines developed a sustained ELISA antibody response to homologous and heterologous pili, but the latter titres were approximately 40% as high as the homologous pilus antibody rises. There were, however, no increases in inhibition of attachment antibody (IEA) titres. Local antibodies (semen) against homologous and heterologous strains were also elicited (ELISA). The vaccine was safe and did not alter the clinical expression of disease. This gonococcal pilus vaccine composed of a single pilus type failed to protect men against gonococcal urethritis.

Adult↗
PubMed1991

The relationship between trauma and financial and physical well-being among Cambodians in the United States.

This study focused on the relationship between trauma and financial and physical well-being of Cambodian refugees in the United States. Trauma was defined by three variables: whether or not trauma had been experienced in Cambodia, the number of traumas experienced, and the number of years spent in refugee camps. It was hypothesized that these trauma variables would predict financial and physical health among Cambodians in the United States. A discriminant analysis showed significant relationships between the trauma variables and current employment status, and multiple regression analyses showed that trauma predicted income and physical health.

Adaptation, Psychological↗
PubMed1991

Human immunization with Pgh 3-2 gonococcal pilus results in cross-reactive antibody to the cyanogen bromide fragment-2 of pilin.

In 1983, a gonococcal pilus vaccine failed to show protection in a large, placebo-controlled, double-blind field trial. The epitopic response to this vaccine was investigated in a random subgroup of 20 vaccine recipients. Using Western blot analysis of the immunizing pilus and its cyanogen bromide (CNBr) fragments, IgG antibody to pilin was detected before immunization in all individuals. Preexistent antibody to the CNBr-2 and CNBr-3 fragments of pilin was detected in 65% and 5% of individuals, respectively. Pilus immunization resulted in a vigorous response to the CNBr-2 fragment in 100% of the individuals tested; only 33% developed antibody to the CNBr-3 fragment. Absorptions of postimmunization sera with different gonococcal strains resulted in either complete or partial removal of antibody to the CNBr-2 fragment. In the context of an unsuccessful vaccine trial, these results suggest that antibody to the CNBr-2 fragment of pilin may not be protective.

Adult↗