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Biomedical subjects

D Hoover

Publications and source records attributed to D Hoover.

At least 19 recordsLinked to original sources
PubMed2001

Factors associated with prevalent hepatitis C: differences among young adult injection drug users in lower and upper Manhattan, New York City.

OBJECTIVES: This study examined correlates of prevalent hepatitis C virus (HCV) infection among young adult injection drug users in 2 neighborhoods in New York City. METHODS: Injection drug users aged 18 to 29 years were street recruited from the Lower East Side and Harlem. Participants were interviewed about drug use and sex practices; venipuncture was performed for hepatitis B virus (HBV), HCV, and HIV serologies. RESULTS: In both sites, testing positive for HCV antibody (anti-HCV) was associated with having injected for more than 3 years. Additionally, HCV infection was positively associated with injecting with someone known to have had hepatitis (but the association was significant only in the Lower East Side) and with sharing cotton (but the association was statistically significant only in Harlem). Being in drug treatment and older than 24 years were associated with HCV in the Lower East Side but not in Harlem. Receiving money for sex was associated with anti-HCV positivity in Harlem but not in the Lower East Side. CONCLUSIONS: Several differences in factors associated with prevalent HCV infection existed among 2 populations of young injection drug users from the same city. Indirect transmission of HCV may occur.

Adolescent↗
PubMed2000

Lead effects on protamine-DNA binding.

BACKGROUND: Lead impairs male fertility and may affect offspring of exposed males, but the mechanisms for this impairment are not completely clear. Protamine P1 and P2 families pack and protect mammalian sperm DNA. Human HP2 is a zinc-protein and may have an important role in fertility. As lead has affinity for zinc-containing proteins, we evaluated its ability in vitro to bind to HP2 and its effects on HP2-DNA binding. Methods and Results UV/VIS spectroscopic data indicated that HP2 binds both Pb(2+) and Zn(2+)(as chloride salts). They also provided evidence that thiol groups mainly participate for Zn(2+)-binding; however, HP2 has additional binding sites for Pb(2+). The mobility shift assay showed that lead interaction with HP2 caused a dose-dependent decrease on HP2 binding to DNA, suggesting that lead may alter chromatin stability. CONCLUSIONS: These in vitro results demonstrate that lead can interact with HP2 altering the DNA-protamine binding. This chemical interaction of lead with protamines may result in chromatin alterations, which in turn may lead to male fertility problems and eventually to DNA damage.

Chromatin↗
PubMed2000

Health effects of depleted uranium on exposed Gulf War veterans.

A small group of Gulf War veterans possess retained fragments of depleted uranium (DU) shrapnel, the long-term health consequences of which are undetermined. We evaluated the clinical health effects of DU exposure in Gulf War veterans compared with nonexposed Gulf War veterans. History and follow-up medical examination were performed on 29 exposed veterans and 38 nonexposed veterans. Outcome measures employed were urinary uranium determinations, clinical laboratory values, and psychiatric and neurocognitive assessment. DU-exposed Gulf War veterans with retained metal shrapnel fragments are excreting elevated levels of urinary uranium 7 years after first exposure (range 0.01-30.7 microg/g creatinine vs 0.01- 0.05 microg/g creatinine in the nonexposed). The persistence of the elevated urine uranium suggests on-going mobilization from a storage depot which results in a chronic systemic exposure. Adverse effects in the kidney, a presumed target organ, are not present at this time, though other effects are observed. Neurocognitive examinations demonstrated a statistical relationship between urine uranium levels and lowered performance on computerized tests assessing performance efficiency. Elevated urinary uranium was statistically related to a high prolactin level (>1.6 ng/ml; P=0.04). More than 7 years after first exposure, DU-exposed Gulf War veterans with retained metal fragments continue to excrete elevated concentrations of urinary uranium. Effects related to this are subtle perturbations in the reproductive and central nervous systems.

Adult↗
PubMed2000

Plasma and breast milk vitamin A as indicators of vitamin A status in pregnant women.

Breast milk vitamin A is not well characterized as an indicator of vitamin A status in women with infections. A controlled trial of vitamin A, 3 mg retinol equivalent/day, was conducted among 697 pregnant women with human immunodeficiency virus (HIV) infection in Malawi which allowed comparison of plasma versus breast milk vitamin A as indicators of vitamin A status. Retinol concentrations were measured in plasma at baseline (18-28 weeks) and 38 weeks gestation and breast milk at 6 weeks post-partum. Plasma alpha 1-acid glycoprotein (AGP) and C-reactive protein (CRP) were measured at baseline. Plasma retinol (geometric mean, SD) at 38 weeks was 0.72 (0.44, 1.18) and 0.61 (0.38, 0.98) mumol/L (P < 0.0002) and breast milk retinol was 1.32 (0.71, 2.43) and 0.95 (0.49, 1.82) mumol/L (P < 0.0001) in vitamin A and placebo groups, respectively. Women with elevated acute phase protein (AGP > 1 gm/L and/or CRP > 5 mg/L) at baseline who received vitamin A had significantly higher plasma and breast milk vitamin A at follow-up compared with placebo. Elevated acute phase proteins did not distinguish women with low body stores of vitamin A. Breast milk retinol appears to be a better indicator of vitamin A status than plasma retinol in women with infections.

Adult↗
PubMed2000

Tietz syndrome (hypopigmentation/deafness) caused by mutation of MITF.

Patients with Tietz syndrome have congenital profound deafness and generalised hypopigmentation, inherited in a fully penetrant autosomal dominant fashion. The pigmentary features and complete penetrance make this syndrome distinct among syndromes with pigmentary anomalies and deafness, which characteristically have patchy depigmentation and variable penetrance. Only one family has been reported with the exact features described in the original report of this syndrome. This family was reascertained and a missense mutation was found in the basic region of the MITF gene in family members with Tietz syndrome. Mutations in other regions of this gene have been found to produce Waardenburg syndrome type 2 (WS2), which also includes pigmentary changes and hearing loss, but in contrast to Tietz syndrome, depigmentation is patchy and hearing loss is variable in WS2.

Adolescent↗
PubMed1999

Total chemical synthesis and high-resolution crystal structure of the potent anti-HIV protein AOP-RANTES.

BACKGROUND: RANTES is a CC-type chemokine protein that acts as a chemoattractant for several kinds of leukocytes, playing an important pro-inflammatory role. Entry of human immunodeficiency virus-1 (HIV-1) into cells depends on the chemokine receptor CCR5. RANTES binds CCR5 and inhibits HIV-1 entry into peripheral blood cells. Interaction with chemokine receptors involves a distinct set of residues at the amino terminus of RANTES. This finding was utilized in the development of a chemically modified aminooxypentane derivative of RANTES, AOP-RANTES, that was originally produced from the recombinant protein using semisynthetic methods. RESULTS: AOP-RANTES has been produced by a novel total chemical synthesis that provides efficient, direct access to large amounts of this anti-HIV protein analog. The crystal structure of chemically synthesized AOP-RANTES has been solved and refined at 1.6 A resolution. The protein is a dimer, with the amino-terminal pentane oxime moiety clearly defined. CONCLUSIONS: Total chemical synthesis of AOP-RANTES provides a convenient method of producing the multi-milligram quantities of this protein needed to investigate the molecular basis of receptor binding and antiviral activity. This work provides the first truly high-resolution structure of a RANTES protein, although the structure of RANTES was known from previous nuclear magnetic resonance (NMR) determinations.

Amino Acid Sequence↗
PubMed1999

Drug network characteristics as a predictor of cessation of drug use among adult injection drug users: a prospective study.

Few studies have examined recovery from opiate and cocaine dependence without treatment, referred to as "natural recovery," "spontaneous recovery," and "spontaneous remission." The present study examined the relationship between network characteristics and cessation of heroin, cocaine, and crack use in a sample of underclass inner-city injection drug users in Baltimore, Maryland. Participants were enrolled in an experimental human immunodeficiency virus (HIV) preventive intervention. Between the baseline and follow-up interviews, which averaged 5.2 months, 24 (7%) of 335 participants reported ceasing to use heroin, cocaine, and crack. Individuals who had reported cessation of drug use at follow-up had reported at baseline a smaller proportion of their network members with whom they used drugs (p < .02). Using multiple logistic regression analyses and adjusting for baseline drug use, enrollment in drug treatment, and demographic and background variables, cessation of drug use was associated with a lower proportion of personal network members in one's drug network (odds ratio [OR] = 25.4, p < .05). The data from this study suggest that network members have potential for social influence on the cessation of drug use.

Adult↗
PubMed1999

Genetic characterization of a Tn5-disrupted glycosyltransferase gene homolog in Brucella abortus and its effect on lipopolysaccharide composition and virulence.

We constructed a rough mutant of Brucella abortus 2308 by transposon (Tn5) mutagenesis. Neither whole cells nor extracted lipopolysaccharide (LPS) from this mutant, designated RA1, reacted with a Brucella O-side-chain-specific monoclonal antibody (MAb), Bru-38, indicating the absence of O-side-chain synthesis. Compositional analyses of LPS from strain RA1 showed reduced levels of quinovosamine and mannose relative to the levels in the parental, wild-type strain, 2308. We isolated DNA flanking the Tn5 insertion in strain RA1 by cloning a 25-kb XbaI genomic fragment into pGEM-3Z to create plasmid pJM6. Allelic exchange of genomic DNA in B. abortus 2308 mediated by electroporation of pJM6 produced kanamycin-resistant clones that were not reactive with MAb Bru-38. Southern blot analysis of genomic DNA from these rough clones revealed Tn5 in a 25-kb XbaI genomic fragment. A homology search with the deduced amino acid sequence of the open reading frame disrupted by Tn5 revealed limited homology with various glycosyltransferases. This B. abortus gene has been named wboA. Transformation of strain RA1 with a broad-host-range plasmid bearing the wild-type B. abortus wboA gene resulted in the restoration of O-side-chain synthesis and the smooth phenotype. B. abortus RA1 was attenuated for survival in mice. However, strain RA1 persisted in mice spleens for a longer time than the B. abortus vaccine strain RB51, but as expected, neither strain induced antibodies specific for the O side chain.

Animals↗
PubMed1998

Prognostic indicators for AIDS and infectious disease death in HIV-infected injection drug users: plasma viral load and CD4+ cell count.

CONTEXT: Plasma human immunodeficiency virus type 1 (HIV-1) viral load and CD4+ cell count are used to predict prognosis of persons infected with HIV. However, whether combining these markers improves prognostic accuracy and whether they predict prognosis for injection drug users (IDUs) and nonwhite persons infected with HIV has not been extensively investigated. OBJECTIVE: To evaluate plasma viral load and CD4+ cell count as prognostic indicators for the acquired immunodeficiency syndrome (AIDS) and infectious disease deaths. DESIGN: Cohort study initiated in 1988 and 1989 with follow-up for up to 7.9 years. PARTICIPANTS: Injection drug users infected with HIV recruited from the community in Baltimore, Md. MAIN OUTCOME MEASURES: Plasma HIV-1 RNA and CD4+ cell count measured at baseline compared with time to first clinical AIDS diagnosis and death due to an infectious disease. RESULTS: Of 522 subjects, 96% were African American, 80% were male, 96% injected drugs within the past 6 months, and the median age was 33 years. A total of 146 cases of AIDS and 119 infectious disease deaths were seen during a median follow-up period of 6.4 years. Time-fixed baseline levels of viral load and CD4+ cell count were independent predictors of progression to AIDS and infectious disease deaths, but in proportional hazards models, viral load had better predictive value than CD4+ cell count. Kaplan-Meier analysis of time to AIDS and to infectious disease deaths by viral load (<500, 500-9999, 10000-29 999, > or =30000 copies/mL) at 3 levels of CD4+ cell count (<0.20, 0.20-0.49, and > or =0.50x10(9)/L [<200,200-499, and > or =500/microL]) was reduced to a 5-stage classification scheme using a backward stepwise regression procedure. The 5-year cumulative probabilities for AIDS and infectious disease deaths ranged from 0% and 0%, respectively, for group I (viral load, <500 copies/mL; CD4+ cell count, 0.50x10(9)/L) to 81.2% and 76.1% respectively, for group V (viral load, > or =10000 copies/mL; CD4+ cell count, 0.20x10(9)/L). CONCLUSIONS: In this study, plasma HIV-1 viral load independently and in combination with CD4+ cell count measurements provided powerful prognostic information for progression to AIDS and death caused by infectious disease in a population of predominantly African American IDUs. Combining categories of both markers provided a simple method for prognostically staging HIV disease.

AIDS-Related Opportunistic Infections↗
PubMed1998

Family history of alcoholism and hypothalamic opioidergic activity.

BACKGROUND: This study was designed to assess whether nonalcoholic offspring from families with a high density of alcohol-dependent individuals have altered endogenous central nervous system opioid activity. Naloxone hydrochloride stimulates plasma cortisol by blocking opioidergic input on the corticotropin-releasing factor neuron, thereby providing a noninvasive method for measuring hypothalamic opioid tone. METHODS: Forty-eight nonalcoholic subjects aged 18 to 25 years were enrolled in a protocol to measure endogenous opioid activity by inducing opioid receptor blockade with the receptor antagonist, naloxone. Twenty-six subjects were offspring from families with a high density of alcohol dependence and were designated as family history-positive subjects. Twenty-two subjects were biological offspring of nonalcohol-dependent parents and designated as family history-negative subjects. Subjects received naloxone hydrochloride (0, 125, and 375 microg/kg) in double-blind, randomized order. Serum cortisol levels were monitored. RESULTS: Family history-negative subjects had a graded cortisol response to each dose of naloxone. In contrast, family history-positive subjects achieved a maximal cortisol response to the 125-microg/kg dose of naloxone hydrochloride with no further increase in cortisol levels observed following the 375-microg/kg dose. Family history-negative subjects had a diminished cortisol response to the 125-microg/kg dose compared with the family history-positive subjects. Plasma naloxone concentrations did not differ between family history groups. CONCLUSIONS: Individuals from families with a high density of alcohol dependence are more sensitive to naloxone compared with offspring of nonalcohol-dependent parents. This implies that individuals with a family history of alcohol dependence have diminished endogenous hypothalamic opioid activity.

Adolescent↗
PubMed1998

Maternal vitamin A deficiency and infant mortality in Malawi.

The relationship between maternal vitamin A deficiency during pregnancy and infant mortality is unclear. We conducted a prospective cohort study of 377 HIV-negative women and their infants in Blantyre, Malawi. Serum vitamin A levels were measured during the second or third trimester of pregnancy and infants were followed during the first year of life. From delivery until 12 months of age, 18 infants died (47.7 per 1000). Mothers of infants who died had lower serum vitamin A levels during pregnancy (0.74 +/- 0.13 mumol/l) compared with mothers of infants who did not die (1.02 +/- 0.03 mumol/l) (p = 0.055). Infants born to women whose vitamin A levels were in the lowest quartile (< 0.32 mumol/l) had three-fold higher likelihood of mortality than infants born to women whose vitamin A levels were in the higher quartiles (p < 0.03). These results suggest that maternal vitamin A deficiency during pregnancy may contribute to higher infant mortality rates.

Adult↗
PubMed1997

Maternal vitamin A deficiency and child growth failure during human immunodeficiency virus infection.

Although vitamin A is thought to influence growth, the relationship between maternal vitamin A deficiency during pregnancy and child growth is unknown. A longitudinal cohort study of 467 HIV-infected women and their children was conducted in Blantyre, Malawi. The children's weight and height were measured every 3 months until they were 24 months old. Maternal vitamin A deficiency was independently related to both linear and ponderal growth after adjustment for effects of body mass index, child gender, and child HIV status. By 12 months of age, infants born to mothers who were vitamin A-deficient during pregnancy weighed approximately 8% less (p < 0.001) and were approximately 2% shorter (p < 0.001) than infants born to mothers who were not deficient. This study suggests children born to HIV-infected women who are vitamin A-deficient during pregnancy are more likely to have growth failure.

Age Factors↗
PubMed1997

Dependence of the hazard of AIDS on markers.

OBJECTIVE: To investigate the dependence of the hazard of symptomatic AIDS on various markers using a non-parametric method. The markers we consider are measures of time (time since infection and calendar date), measures of immune function (numbers and percentage of CD4 T cells) and serological activation markers (neopterin and beta 2-microglobulin). METHODS: We adapted a non-parametric statistical method to estimate the hazard of AIDS. We considered both univariate analyses, in which each marker was considered separately and bivariate analyses of pairs of markers. CONCLUSIONS: Using data from 356 seroconverters from the Multicenter AIDS Cohort Study, we found that in the univariate analyses the hazard of AIDS is dependent on all markers, with the strongest dependence for CD4 count and CD4 percentage. In the bivariate analyses we found that the time since infection is of little importance in determining the hazard of AIDS if the CD4 count or percentage are known, and is of minor additional value if one of the serological markers is known. In contrast, we found that both beta 2-microglobulin and neopterin do add some additional information to the hazard of AIDS if CD4 count or CD4 percentage are known.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Cloning of a Brucella melitensis group 3 antigen gene encoding Omp28, a protein recognized by the humoral immune response during human brucellosis.

Brucella group 3 antigens (Ags) are outer membrane proteins (OMPs) with a molecular mass ranging from 25 to 30 kDa. The OMPs are of interest partially because of their potential use as vaccine and diagnostic reagents. We used human convalescent antibody (Ab) to clone a gene that encoded a 28-kDa protein from a lambdagt11 library of Brucella melitensis 16M genomic DNA. DNA sequence analysis revealed a single open reading frame that would encode a protein of 26,552 Da. The 28-kDa protein had a primary amino acid sequence that was 43% similar to a previously described Brucella abortus group 3 Ag, Omp25 (P. de Wergifosse, P. Lintermans, J. N. Limet, and A. Cloeckaert, J. Bacteriol. 177:1911-1914, 1995). The similarity to a known group 3 OMP, immunoreactivity with Ab prepared against B. abortus group Ags, immunolabeling of whole cells, and Southern hybridization led to our conclusion that the B. melitensis 28-kDa protein was a group 3 protein distinct from B. abortus Omp25. We designated the B. melitensis protein Omp28. Human convalescent sera from patients infected with B. abortus and Brucella suis as well as rabbit antisera prepared against killed B. abortus whole cells recognized B. melitensis Omp28 on Western blots (immunoblots). Furthermore, mice and goats infected with smooth strains of B. melitensis produced Abs against Omp28. Our results may begin to explain the variability in molecular weight seen in Brucella group Ags and point toward their possible use in vaccination against infection as well as diagnosis of the disease.

Amino Acid Sequence↗
PubMed1996

Mitogenic activities of amino acid substitution mutants of staphylococcal enterotoxin B in human and mouse lymphocyte cultures.

Site-directed mutagenesis has been used to introduce amino acid substitutions at specific residues of the staphylococcal enterotoxin B (SEB) gene cloned from Staphylococcus aureus 10-275. The mitogenic activities of these derivatives were determined in two assay systems: (i) mouse spleen cells and (ii) a mixture of human peripheral blood mononuclear cells and lymphocytes. Substitution of either His-12, His-32, His-121, His-166, Lys-152, or Gly-205 did not significantly alter the mitogenic activity from that of the wild-type toxin in either proliferation assay. Substitution of either residue Asn-23, Phe-44, or Cys-93 reduced the mitogenicity of SEB by a degree that depended upon the assay system used. Similar to the results reported by others measuring toxin activation of mouse lymphoid cells, we found that substitutions of these three residues of SEB caused at least 800-fold reductions of mitogenic activity from that of the wild-type toxin. When tested for toxicity in vivo in D-galactosamine-treated mice, the reduced activities of these mutant toxins, however, were not as pronounced. In contrast, when tested in the human cell mitogenicity assay, these mutant toxins were active. Small alterations in activity (two- to fivefold reduction) were observable only at low concentrations. Our findings reveal the importance of using human lymphocytes in addition to the traditional mouse spleen cell assay when assessing biological activities of staphylococcal enterotoxins.

Animals↗