Biomedical subjects

K E Nelson

Publications and source records attributed to K E Nelson.

At least 127 records · Page 7Linked to original sources

PubMed1995

Dynamics of risk behavior for HIV infection among young Thai men.

The objective of this investigation was to analyze the dynamics of risk for HIV-1 infection among young men in Thailand. We conducted a prospective study in a cohort (n = 1,236) of young men, aged 19-23 years at conscription into the Royal Thai Army and Air Force from six provinces in northern Thailand in May 1991 who were followed until their discharge in April 1993. The outcome measure was change since conscription in the frequency of self-reported sex with female commercial sex workers (CSW) during military service. Although 42% of conscripts reported no visit to a female CSW in the year prior to conscription, most had a visit during military service. Men who visited female CSWs infrequently at baseline increased their visits somewhat over time, whereas those with high initial rates of CSW visits decreased. Based on an assumed stable distribution over time, change from baseline was not statistically significant. Only marital status and high baseline CSW visit rates were associated with diminished visit frequency in multivariate analysis. No differences were seen in patterns of change in CSW visits by HIV-1 serostatus. More aggressive preventive interventions are needed to reduce the frequency of CSW visits in northern Thailand, a setting where 40-80% of all female CSWs working in brothels are now HIV seropositive.

Adult↗

PubMed1995

Instability of delayed-type hypersensitivity skin test anergy in human immunodeficiency virus infection.

OBJECTIVE: To evaluate stability of delayed-type hypersensitivity (DTH) skin test over time in human immunodeficiency virus (HIV)-seropositive and HIV-seronegative injecting drug users. METHOD: A community-based cohort of injecting drug users who had serial skin testing with purified protein derivative tuberculin, mumps, and Candida albicans antigen. Delayed-type hypersensitivity anergy was defined as a skin test result of less than 3 mm for all three antigens; DTH positivity was a skin test result of 3 mm or greater for at least one antigen (Centers for Disease Control and Prevention, Atlanta, Ga, 1993). RESULTS: At baseline, 36% of HIV-seropositive subjects (n = 401) were anergic as compared with 14% of HIV-seronegative subjects (n = 552; P < .001). During follow-up, fewer HIV-seropositive subjects remained DTH positive (42%) and more remained anergic (19%) than of HIV-seronegative subjects (67% and 7%, respectively). Twenty-four percent of HIV-seropositive subjects who were initially DTH positive became anergic as compared with 15.3% of the HIV-seronegative subjects. However, the proportion changing from anergy to DTH positivity was greater among HIV-seropositive subjects (15%) than HIV-seronegative subjects (12%). In comparison to those who remained DTH positive, HIV-seropositive subjects with CD4 cell counts of less than 0.50 x 10(9)/L (odds ratio = 6.4) and less than 0.35 x 10(9)/L (odds ratio = 11.2) were more likely to remain anergic than those who had CD4 cell counts above 0.50 x 10(9)/L or were HIV seronegative. CONCLUSIONS: Although the prevalence and incidence of DTH anergy were higher in HIV-seropositive subjects, high rates of change in DTH status occurred in both directions. This suggests that instability of DTH skin testing is substantial and only partially dependent on HIV status. Although a single test may be an unreliable indicator of HIV-induced immunosuppression, two consecutive anergic readings were strongly associated with a CD4 cell count below 0.50 x 10(9)/L and particularly below 0.35 x 10(9)/L. For determining false negativity of tuberculin tests, persistent DTH anergy is more reliable than a single test among HIV-seropositive injecting drug users. Anergy testing appears to be unnecessary with CD4 cell counts greater than 0.5 x 10(9)/L.

Adult↗

PubMed1995

Seroepidemiology of hepatitis B virus in a population of injecting drug users. Association with drug injection patterns.

To investigate the epidemiology of hepatitis B virus (HBV) infection among injecting drug users, the authors assessed the prevalence of HBV seromarkers among 2,558 injecting drug users recruited through street outreach in Baltimore, Maryland, in 1988-1989. Eighty percent of the drug users had at least one HBV seromarker. HBV seropositivity was associated with increasing age, duration of injecting drug use, African-American ethnicity, injecting drugs at least once daily, and sharing needles or visiting "shooting galleries" during the previous 11 years, but not with high-risk sexual behaviors or a history of sexually transmitted disease. This finding is possibly due to the relative inefficiency of sexual transmission as compared with parenteral transmission in injecting drug users. In addition, HBV seropositivity was strongly associated with seropositivity for hepatitis C virus and human immunodeficiency virus. The authors conclude that HBV transmission among injecting drug users occurs primarily through the sharing of contaminated drug injecting equipment rather than through sexual relations, and that efforts to prevent HBV infection must target injecting drug users early in their injecting careers.

Adult↗

PubMed1995

Activation of the classical pathway of complement by tobacco glycoprotein (TGP).

Tobacco glycoprotein (TGP), a polyphenol-rich glycoprotein isolated from tobacco leaves, activates the classical complement pathway through a mechanism that appears to involve direct interaction with C1q. A binding site on C1q for TGP can be localized by competitive inhibition with DNA to a region located in the junction between the collagen-like and globular regions of the molecule. A protein with activity similar to TGP has also been isolated from cigarette smoke condensate (TGP-S); it shares a binding site on C1q with TGP and has similar functional activity, with the exception that complement activation does not proceed to formation of a C3 cleaving enzyme. The ability of TGP and TGP-S to activate complement can be partially duplicated using polyphenols associated with tobacco leaf and smoke, i.e., chlorogenic acid and rutin. These polyphenols also compete with TGP for a binding site on immobilized C1q, suggesting that the polyphenol portion of TGP is critical for activation of complement. These results provide an additional mechanism for complement activation by cigarette products that, in vivo, could result in a localized complement depletion, generation of biologically active complement cleavage products, and initiation of an inflammatory response.

Complement Activation↗

PubMed1995

Temporal trends of incident human immunodeficiency virus infection in a cohort of injecting drug users in Baltimore, Md.

OBJECTIVE: To measure the temporal trends in the incidence of infection with human immunodeficiency virus in a cohort of injecting drug users in Baltimore, Md, between 1988 and 1992. DESIGN: Study subjects were screened for antibodies to human immunodeficiency virus by enzyme-linked immunosorbent assay and confirmed with Western blot. They were followed up at 6-month intervals with repeated serologic screening and comprehensive interviews for human immunodeficiency virus risk factors. SETTING: Special study clinic. PARTICIPANTS: A cohort of 2960 participants were recruited and screened between February 1988 and March 1989. Recruitment criteria included an age of 18 years or older, a history of illicit drug injection since 1978, and the absence of the acquired immunodeficiency syndrome; subjects were subsequently tested for human immunodeficiency virus antibodies. Most subjects (85%) were not receiving methadone treatment at baseline and were recruited by word of mouth. MAIN OUTCOME MEASURE: Human immunodeficiency virus seroconversion. RESULTS: Of the 2247 seronegative participants at baseline, 1532 were followed up, and 188 (12.3%) had seroconverted by December 1992. The incidence of human immunodeficiency virus infection over time among users declined somewhat, especially among women; the overall incidence was 1.90 per 100 person-semesters, or 3.80% annually. The incidence, adjusted for gender, was higher in younger (< 35 years) than older (> or = 35 years) subjects (relative incidence, 1.75; 95% confidence interval, 1.29 to 2.38) and in women compared with men, adjusted for age (relative incidence, 1.29; 95% confidence interval, 0.95 to 1.80). The relative incidence among active compared with inactive drug users adjusted for age and gender was 1.58 (95% confidence interval, 1.06 to 2.35). CONCLUSIONS: Although the incidence of human immunodeficiency virus infection in this cohort of injecting drug users in Baltimore declined somewhat during the 4 years of follow-up, especially among women, the persistent annual incidence of nearly 4% during 3 1/2 to 4 1/2 years of observation suggests the need for additional strategies for prevention of infection, especially among those who continue injecting drugs. Newer methods of prevention, such as provision of sterile injection equipment, an effective human immunodeficiency virus vaccine, and wider availability of effective treatment or prevention of drug addiction, are urgently needed in these high-risk populations.

Adult↗

PubMed1995

Increasing reading and communication skills in children with autism through an interactive multimedia computer program.

This paper reports on the effect of using an interactive and child-initiated microcomputer program (Alpha) when teaching three groups of children (N = 30) reading and communications skills: (a) 11 children with autism (M chronological age, CA = 9:4 years), (b) 9 children with mixed handicaps (M CA = 13:1), and (c) 10 normal preschool children (M CA = 6:4 years). Their mental age varied from 5:8 years to 6:9 years and all children received computer instruction supplementary to their regular reading and writing activities. Tests of reading and phonological development were carried out at the onset of the training (Start), at the end (Post 1), and at a follow-up evaluation (Post 2). In addition, video observations of the childrens' verbal and nonverbal communication were added at Start and Post 1. The children with autism increased both their word reading and their phonological awareness through the use of the Alpha program. Clearly significant gains were observed during the intervention, but none during the follow-up period. A similar but weaker pattern is observed for the children with mixed handicaps. In contrast, the normal preschool children increased their scores regardless of the program. Analyses of the children's classroom behavior indicate that the intervention succeeded in stimulating verbal expressions among the children with autism and mixed handicap. A significant increase in enjoyment was also noted for the children with autism. It is concluded that the intervention with a motivating multimedia program might stimulate reading and communication in children with various developmental disabilities, but that such interventions must be individually based and include both detailed planning and monitoring from teachers, and parents, as well as from clinicians in charge.

Adolescent↗

PubMed1995

Time course of detection of viral and serologic markers preceding human immunodeficiency virus type 1 seroconversion: implications for screening of blood and tissue donors.

BACKGROUND: Almost all human immunodeficiency virus (HIV) transmission via blood or tissues that has occurred since anti-HIV screening was implemented in 1985 is traceable to blood given after infection but before antibody seroconversion, a time that is referred to as the window period. In this study, the performance of newer assays designed to detect viral and serologic markers soon after infection is assessed, and the reduction in the window period achieved by these assays is estimated. STUDY DESIGN AND METHODS: Three cohort studies of persons at high risk for acquiring HIV infection were identified. These studies included well-controlled HIV type 1 (HIV-1) polymerase chain reaction (PCR) analyses of serial preseroconversion specimens from HIV-1-seroconverting homosexual men or intravenous drug users. Of 81 enrollees with anti-HIV-1 seroconversion documented by a viral lysate anti-HIV-1 enzyme immunosorbent assay (EIA) available in 1989, 13 (16%) had PCR-positive preseroconversion specimens. In the present study, sera from these 13 PCR-positive samples were further tested for anti-HIV by 10 contemporary EIAs and 6 supplemental assays, as well as being tested for plasma p24 antigen and HIV-1 RNA. Preseroconversion sera from 38 HIV-1 DNA PCR-negative cohort participants were also tested by selected anti-HIV EIAs and tested for p24 antigen and HIV-1 RNA. On the basis of these laboratory data and the intervals between blood drawing in all 81 men, the reduction in the preseroconversion window period achieved by these new assays was estimated with a mathematical model developed to analyze seroconversion data. RESULTS: Nine (69%) of the 13 preseroconversion PCR-positive samples had anti-HIV that was detectable by one or more contemporary anti-HIV-1 or anti-HIV type 2 EIA. Supplemental antibody assays were negative on all four EIA-nonreactive preseroconversion samples and negative or indeterminate on a high proportion of the nine EIA-reactive PCR-positive samples. Eight (61%) of the 13 samples were p24 antigen-positive, and 11 (85%) were HIV-1 RNA-positive. The estimated reductions in the window period (relative to the index viral lysate-based anti-HIV EIA) were as follows: contemporary anti-HIV-1/2 EIAs, 20.3 days (95% Cl, 8.0-32.5); p24 antigen and DNA PCR, 26.4 days (95% Cl, 12.6-38.7); and RNA PCR, 31.0 days (95% Cl, 16.7-45.3). CONCLUSION: Recent improvement in the sensitivity of anti-HIV assays has resulted in significant shortening of the preseroconversion window period. Consequently, the incremental reduction in the window period that could be achieved by implementing direct virus-detection assays has diminished significantly.

Blood Donors↗

PubMed1995

Infectious disease markers in blood donors in northern Thailand.

BACKGROUND: A major epidemic of human immunodeficiency virus type 1 (HIV-1) infections that are primarily due to heterosexual transmission has developed in Thailand since 1988. The epidemic has been most severe in northern Thailand. The blood banks in Chiang Mai began screening donors for HIV-1 antibodies in February 1988 and for p24 antigen in April 1992. STUDY DESIGN AND METHODS: The trends of HIV-1 antibody prevalence were analyzed by type of donor (i.e., paid, replacement, and voluntary) for the period of 1988 through 1993. In addition, the prevalence of HIV-1 p24 antigen and of antibodies to syphilis, hepatitis B surface antigen, and hepatitis C virus was evaluated among blood donors at Chiang Mai University Hospital and the Thai Red Cross blood banks in Chiang Mai. RESULTS: The prevalence of HIV-1 antibodies increased from 0.84 percent in 1988 to 4.04 percent in 1991. Seropositivity was highest in paid professional donors. After discontinuation of the use of paid donors in 1993, HIV-1 antibody prevalence decreased to 3.34 percent. Antibody prevalence in replacement donors increased from 0.56 percent in 1988 to 5.82 percent in 1991. Among 44,446 donors tested, 7 (0.016%) were HIV-1 p24 antigen positive but antibody negative. CONCLUSION: The exclusion of paid donors and the use of p24 antigen testing are justified in northern Thailand. Additional strategies to exclude donors at very high risk and to attract those at low risk for infection should be developed and evaluated to increase blood transfusion safety in this and other, similar populations.

Acquired Immunodeficiency Syndrome↗

PubMed1995

Willingness to participate in AIDS vaccine trials among high-risk populations in northern Thailand.

OBJECTIVES: To determine the anticipated participation in a prophylactic AIDS vaccine trial and to identify perceived benefits and barriers to enrollment of HIV-seronegative volunteers at risk of HIV infection in northern Thailand. DESIGN: A cross-sectional survey. METHODS: Subjects interviewed in a cross-sectional survey included female commercial sex workers (n = 215), men attending sexually transmitted disease clinics (n = 219), conscripts in the Royal Thai Army (n = 1453), and men discharged from the army (n = 293) who had returned to civilian life. We determined AIDS vaccine knowledge and attitudes, perceived vulnerability to HIV infection, barriers and incentives to participate in a future vaccine trial and agreement to participate in a randomized trial. RESULTS: Awareness of vaccines (88-97%) and AIDS vaccine development efforts (62-77%) were common and viewed to be a complement to behavior change (74-94%). Approximately 25% of subjects would definitely join a trial if asked, and an additional 38% would accept an AIDS vaccine if they were convinced it would be safe and effective. Important barriers to participation included concerns with discrimination (16-45%), short- (37-60%) and long-term (30-55%) vaccine side-effects, fear of disability and death (36-58%), and beliefs that partners would refuse to have sex (24-49%) after immunization. The principal inducement to join a trial was health insurance (62%). CONCLUSION: Potential HIV vaccine trial participants have several fears of joining a vaccine study at this time. Information derived from Phase I/II trials is needed to address these concerns if enrollment in efficacy trials is to be successful in the near future.

AIDS Vaccines↗

PubMed1995

Correlates of hepatitis C virus infections among injection drug users.

Injection drug users are at high risk for hepatitis C virus (HCV) infection. In Baltimore, Maryland, the prevalence of anti-HCV is greater among injection drug users who are black, human immunodeficiency virus (HIV) infected, have injected longer, have injected more frequently, and have injected cocaine than among other injection drug users. HCV infection occurs quickly after the initiation of injecting illicit drugs, with 78% of study participants anti-HCV positive after 2 years of injecting. The prevalence of anti-HCV among injection drug users does not appear to be related to socioeconomic factors or sexual practices. Some injection drug users remain free of anti-HCV even after years of injecting and serologic evidence of other bloodborne pathogens. Some of these injection drug users have HCV infection, demonstrated by HCV RNA in their sera. However, the basis for viral persistence in the absence of anti-HCV and for the absence of HCV infection in long-term drug users is not known. Further studies are indicated to determine the mechanism or mechanisms for the absence of anti-HCV in persons exposed to the virus, because the biologic basis for this condition may elucidate the elements missing in the immune response of the majority of HCV-exposed persons who acquire persistent infection. In addition, interventions to prevent HCV infections should be applied in populations at risk for injection drug use early or before drug use begins.

Adolescent↗

PubMed1995

Isolation and characterization of an anaerobic ruminal bacterium capable of degrading hydrolyzable tannins.

An anaerobic diplococcoid bacterium able to degrade hydrolyzable tannins was isolated from the ruminal fluid of a goat fed desmodium (Desmodium ovalifolium), a tropical legume which contains levels as high as 17% condensed tannins. This strain grew under anaerobic conditions in the presence of up to 30 g of tannic acid per liter and tolerated a range of phenolic monomers, including gallic, ferulic, and p-coumaric acids. The predominant fermentation product from tannic acid breakdown was pyrogallol, as detected by high-performance liquid chromatography and mass spectrometry. Tannic acid degradation was dependent on the presence of a sugar such as glucose, fructose, arabinose, sucrose, galactose, cellobiose, or soluble starch as an added carbon and energy source. The strain also demonstrated resistance to condensed tannins up to a level of 4 g/liter.

Animals↗

PubMed1995

The epidemiology of HIV and syphilis among male commercial sex workers in northern Thailand.

OBJECTIVE: To examine the prevalence and incidence of HIV and syphilis, and risk behaviors for these infections, among 1,172 male commercial sex workers (CSW) followed prospectively from 1989 to 1994 in Chiang Mai, northern Thailand. METHODS: Twice yearly visits were conducted by the Thai Ministry of Public Health at all cooperating gay bars and clubs (17 sites) in Chiang Mai City as part of a national HIV sentinel surveillance. Men and boys who agreed were followed prospectively. Sentinel visits included an interview, HIV pre-test counseling, HIV and syphilis serology, condom distribution, and referral for post-test counseling. Participation was voluntary, confidential, and individual HIV results were available only to participating subjects. A total of 219 CSW were seen at least twice, allowing for incidence estimates based on 100 person-years (PY). RESULTS: Median age of male CSW was 20 years. Median time of work as a CSW was 4 months. Most men (57.6%) described themselves as heterosexual. Median number of clients was 2.5 per week, and reported condom use with clients was low: 42% reported inconsistent or no condom use, while 58% reported always using condoms. Reactive Venereal Disease Research Laboratory results were 7.6%, overall, but showed a declining trend. HIV prevalence was 1.4% in June 1989, 13.9% in June 1990, and 20.1% in December 1993, and showed a significant increasing trend. There were 27 incident HIV infections in 227.3 PY of observation, for an overall incidence during the 4.5-year period of 11.9 per 100 PY (95% confidence interval, 7.42-16.38). CONCLUSION: Male CSW in northern Thailand are at high risk for HIV despite current prevention efforts. The majority are heterosexual, which may be an important epidemiologic link in the spread of HIV between male CSW users and heterosexual women in Thailand.

Adolescent↗

PubMed1995

Same-sex behavior, sexually transmitted diseases and HIV risks among young northern Thai men.

OBJECTIVES: To assess the risks for HIV infection and sexually transmitted diseases (STD) among young northern Thai men who have sex with men (MSM), and to examine the possible role of male same-sex behavior in the northern Thai HIV/AIDS epidemic. METHODS: Two cohorts of northern Thai military conscripts and one cohort of recently discharged conscripts, a total of 2047 men, were studied. Data were collected by interview on behavioral risk factors, and sera were examined for syphilis and HIV-1 antibodies. Univariate and multiple logistic regression analyses were used to determine risk factors associated with HIV and STD, and to assess the frequency and patterns of same-sex behaviors among these men. RESULTS: Of 2047 men, 134 (6.5%) reported one or more male lifetime sex partners. Of these MSM, 130 (97.0%) also had female partners, and four (3.0%) had exclusively male partners. Compared with men who reported only female sex partners, MSM had a higher number of lifetime sex partners, a higher mean number of female sex partners, more female and male commercial sex worker (CSW) partners, and were more likely to be married. MSM were significantly more likely than exclusively heterosexual men to report having had any STD [odds ratio (OR), 2.72], gonorrhea (OR, 2.05), syphilis (OR, 3.17), non-gonococcal urethritis (OR, 4.54) and penile discharges (OR, 6.24). They were at borderline increased risk for HIV infection [OR, 1.51; 95% confidence interval (CI), 0.95-2.41]. Men with more than one lifetime male sex partner compared with those with only one partner were significantly more likely to be HIV-infected (OR, 2.81; 95% CI, 1.09-7.19). CONCLUSIONS: Northern Thai MSM are a high-risk population for STD, including HIV. Reported same-sex behavior in this population appears to vary considerably with data collection techniques. HIV and STD prevention strategies aimed at changing unsafe sexual practices may need to be targeted to the general population of young Thai men.

Acquired Immunodeficiency Syndrome↗

PubMed1994

Epidemiology / vaccine efficacy trials. "HIV Incidence in Adults in Northern Thailand".

UNLABELLED: According to an abstract submitted by the authors to the X International Conference on AIDS, held August 7-12, 1994, in Yokohama, Japan, " OBJECTIVE: To measure the HIV-1 incidence, follow-up rates and high risk behaviors in cohorts of seronegative adults in northern Thailand. METHODS: We screened cohorts of female commercial sex workers (CSWs), male STD clinic patients, Royal Thai Army (RTA) conscripts, and discharged RTA conscripts at baseline and q3 to 6 months for HIV infection by ELISA and WB and did interviews for high risk behavior, medical history, and STD cultures. RESULTS: Of 1068 CSWs, 409 (38.3%) were HIV positive, and 396 HIV negative were enrolled in the study; follow-up at 6 months was 70.7% and 19 seroconverted, for an incidence of 12.8/100 person years. Of 1031 male STD patients, 164 (15.9%) were HIV positive, and 264 HIV negative (30.4%) were enrolled; follow-up at 6 months was 91.9% and 6 seroconverted, for an incidence of 4.92/100 person years. Of 969 RTA conscripts, 12.4% were HIV positive at baseline and 90% were followed at 6 months; 3 of 778 seroconverted, for an incidence of 0.87/100 person years. (Previous RTA cohorts have had an incidence of 3.4%/year). Among 380 men discharged from RTA, follow-up at 9 months was 81.8% and the incidence was 5.2/100 person years. Sample sizes required to show an HIV vaccine efficacy of 60%, with a power-.90, alpha-.05 varies from CSUs 644, STD patients 1456 to ex-RTA-1306. CONCLUSIONS: Several populations in northern Thailand appear to have sufficiently high HIV-1 incidence and adequate follow-up for HIV vaccine efficacy trials and other preventive intervention trials.

Asia↗

PubMed1994

Disseminated Penicillium marneffei infection in southeast Asia.

Disseminated infection with the fungal pathogen Penicillium marneffei is, after extrapulmonary tuberculosis and cryptococcal meningitis, the third most common opportunistic infection in HIV disease in northern Thailand. We report the clinical, microbiological, and therapeutic features of a large series of HIV-infected adults with disseminated P marneffei infection. From August, 1987, to June, 1992, 92 patients with P marneffei infection confirmed by culture were seen at Chiang Mai University Hospital, of whom 86 were also infected with HIV. Clinical information was available for 80 of these patients. The most common presenting symptoms and signs were fever (92%), anaemia (77%), weight loss (76%), and skin lesions (71%). 87% of patients presenting with skin lesions had generalised papules with central umbilication. Presumptive diagnosis was made in 50 patients by microscopic examination of Wright's-stained bone-marrow aspirate and/or touch smears of skin biopsy or lymph-node biopsy specimens. Most patients who were diagnosed responded initially to amphotericin or itraconazole, whereas most who were not diagnosed and treated died. 12 patients relapsed within 6 months of cessation of treatment. P marneffei has become an important pathogen of HIV-associated opportunistic infection in Thailand.

AIDS-Related Opportunistic Infections↗

PubMed1994

Direct comparison of the relationship between clinical outcome and change in CD4+ lymphocytes in human immunodeficiency virus-positive homosexual men and injecting drug users.

BACKGROUND AND METHODS: To compare rates of decline of CD4+ lymphocytes among human immunodeficiency virus-positive homosexual men and injecting drug users, we followed up prevalent human immunodeficiency virus-positive homosexual men and current or former injecting drug users from February 1988 through August 1991. Subjects were free of acquired immunodeficiency syndrome at study entry and had semiannual clinical and laboratory evaluation, including measurement of T-cell subsets, under common protocols. Initial levels and rates of change of CD4+ lymphocyte counts were compared according to cohort membership and clinical progression, defined by the development of thrush or an acquired immunodeficiency syndrome--defining illness. Median follow-up was 30 months for both cohorts. RESULTS: At study entry, homosexual men had lower absolute numbers of circulating CD4+ lymphocytes than did injecting drug users (459/microL [0.46 x 10(9)/L] vs 509/microL, respectively). During follow-up, homosexual men exhibited a faster decline in CD4+ lymphocyte counts as well as more frequent development of HIV-related symptoms (thrush or acquired immunodeficiency syndrome). In both cohorts, initial levels of CD4+ lymphocytes and rates of decline in these cells were strongly associated with progression of disease, defined as remaining asymptomatic, onset of thrush, or onset of acquired immunodeficiency syndrome. Once homosexual men and injecting drug users were stratified by disease progression, their initial levels and rates of decline of CD4+ lymphocyte counts were similar. Thus, crude differences between the two study groups largely resulted from differences in development of clinical symptoms. CONCLUSIONS: In these cohorts of homosexual men and injecting drug users, clinical outcome was much more important than risk group membership in determining changes in CD4+ lymphocyte numbers. The close similarity between the groups also suggests that drug use, ethnicity, and socioeconomic status play a minor role in the progression of human immunodeficiency virus infection.

Adult↗

PubMed1994

Social valence in children with specific language impairment during imitation-based and conversation-based language intervention.

This study investigated the level of social valence and type of social behaviors expressed in 15 children with specific language impairment as they engaged in typical language intervention activities during conversation-based and imitation-based language programs. These programs were both applied to each child over a period of several weeks. Videotapes of treatment sessions were analyzed for the presence of five verbal and 11 nonverbal behaviors selected to measure social valence. In addition, the child's level of social valence was scored on a three-point rating scale. The results showed that although both types of treatments were predominantly associated with positive social valence ratings and a high frequency of smiling, laughing, and engagement in the activities, a significantly higher number of these positive ratings and behaviors were noted within conversation-based treatment. In contrast, although negative social valence ratings and expressions of boredom or dislike were very rare, these were observed more frequently under imitation-based treatment. There was a significantly higher rate of verbal initiations in the conversation-based treatment, and a significantly higher rate of quiet, passive participation in the imitation-based treatment. The findings are discussed in relation to treatment selection and viable strategies for assessing treatment acceptability in children.

Child Language↗

PubMed1994

Comparison of conversational-recasting and imitative procedures for training grammatical structures in children with specific language impairment.

The recent literature on language intervention has become increasingly focused upon developing treatments that more closely parallel normal language acquisition. However, there have been relatively few reports that directly compare imitative procedures to conversational-interactive interventions. The purpose of the present study was to compare the relative effectiveness of imitative intervention and conversational recast language intervention applied to a wide range of grammatical morpheme and complex sentence targets in 21 children with specific language impairment. The results indicated that although both kinds of treatments were effective in triggering acquisition of most targets, consistently fewer presentations to first spontaneous use were required in the conversational procedure. In addition, the transition from elicited production to generalized spontaneous production was more rapid under conversation-interactive treatment. Finally, although imitation treatment was more effective in generating elicited production, a significantly greater number of spontaneous productions occurred under the conversational training procedures. The theoretical and applied ramifications of these findings are discussed.

Child↗