Biomedical subjects

Joseph Quinn

Publications and source records attributed to Joseph Quinn.

11 recordsLinked to original sources

PubMed2006

An updated systematic overview of triple combination therapy in antiretroviral-naive HIV-infected adults.

OBJECTIVE: To compare the effectiveness of three drug combination antiretroviral therapy (ART) in treatment-naive HIV-infected persons, and identify the predictors of responses. DESIGN AND METHODS: Overview of trials identified by searching public domain publications and conference presentations. The three-drug combination therapy was defined as two nucleoside reverse transcriptase inhibitors (NRTI) or nucleotide and NRTI, and either: (1) a protease inhibitor (PI); (2) a non-nucleoside RTI (NNRTI); (3) a third NRTI; or (4) a ritonavir-boosted PI (BPI). Week 24 and 48 results for the proportions of patients with plasma HIV RNA levels < 400 and < 50 copies/ml, and change in CD4(+) cell counts were recorded. RESULTS: Fifty-three trials met the entry criteria, and enrolled 14 264 patients into 90 treatment arms. Overall 55% of patients had plasma HIV RNA levels < 50 copies/ml at week 48 and this percentage increased with later publication dates. In unadjusted pairwise comparisons at week 48, significantly greater percentages of patients receiving NNRTI (64%) and BPI (64%) had RNA < 50 copies/ml than NRTI (54%) or PI (43%), and CD4(+) cell count increases were significantly greater in the BPI group (+200 cells/microl) than the PI (+179), NNRTI (+173), or NRTI (+161) groups. Pill count and percentage of patients with week 48 plasma HIV RNA levels < 50 copies/ml were correlated in the univariate analysis (P = 0.0053; r = -0.323), but pill count was not a significant predictor in the multivariate analyses. Drug class and baseline CD4(+) cell counts were significant predictors, but explained only a modest amount of the treatment effect, (R(2) = 0.355). CONCLUSIONS: NNRTI and BPI-containing regimens offer superior virologic suppression over 48 weeks, supporting existing guidelines for the choice of initial ART. Pill count was not a consistent predictor of virologic suppression.

Anti-HIV Agents↗

PubMed2006

Mitochondria are a direct site of A beta accumulation in Alzheimer's disease neurons: implications for free radical generation and oxidative damage in disease progression.

Alzheimer's disease (AD) is a complex, neurodegenerative disease characterized by the impairment of cognitive function in elderly individuals. In a recent global gene expression study of APP transgenic mice, we found elevated expression of mitochondrial genes, which we hypothesize represents a compensatory response because of mitochondrial oxidative damage caused by the over-expression of mutant APP and/or amyloid beta (Abeta). We investigated this hypothesis in a series of experiments examining what forms of APP and Abeta localize to the mitochondria, and whether the presence of these species is associated with mitochondrial dysfunction and oxidative damage. Using immunoblotting, digitonin fractionation, immunofluorescence, and electron microscopy techniques, we found a relationship between mutant APP derivatives and mitochondria in brain slices from Tg2576 mice and in mouse neuroblastoma cells expressing mutant human APP. Further, to determine the functional relationship between mutant APP/Abeta and oxidative damage, we quantified Abeta levels, hydrogen peroxide production, cytochrome oxidase activity and carbonyl proteins in Tg2576 mice and age-matched wild-type (WT) littermates. Hydrogen peroxide levels were found to be significantly increased in Tg2576 mice when compared with age-matched WT littermates and directly correlated with levels of soluble Abeta in Tg2576 mice, suggesting that soluble Abeta may be responsible for the production of hydrogen peroxide in AD progression in Tg2576 mice. Cytochrome c oxidase activity was found to be decreased in Tg2576 mice when compared with age-matched WT littermates, suggesting that mutant APP and soluble Abeta impair mitochondrial metabolism in AD development and progression. An increase in hydrogen peroxide and a decrease in cytochrome oxidase activity were found in young Tg2576 mice, prior to the appearance of Abeta plaques. These findings suggest that early mitochondrially targeted therapeutic interventions may be effective in delaying AD progression in elderly individuals and in treating AD patients.

Alzheimer Disease↗

PubMed2005

Chronic melatonin therapy fails to alter amyloid burden or oxidative damage in old Tg2576 mice: implications for clinical trials.

Melatonin has been proposed as a treatment for Alzheimer's disease based on the demonstration of antioxidant and "anti-amyloid" effects in vitro and in vivo. Chronic melatonin therapy in old, amyloid plaque-bearing transgenic mice was studied. Tg2576 mice started melatonin treatment at 14 months of age. After 4 months of treatment, there were no differences between untreated and melatonin-treated mice in cortical levels of soluble, formic acid extracted, or histologically detectable beta amyloid (Abeta), nor in brain levels of lipid peroxidation product (total 8,12-isoprostane F(2alpha)-VI), despite marked elevations in plasma melatonin. We conclude that melatonin fails to produce anti-amyloid or antioxidant effects when initiated after the age of amyloid plaque deposition. These findings diminish the possibility that melatonin will be useful for the treatment of established Alzheimer's disease.

Aging↗

PubMed2005

Severe hepatotoxicity associated with nevirapine use in HIV-infected subjects.

Human immunodeficiency virus (HIV)-infected South African patients (n=468) received blinded lamivudine or emtricitabine, stavudine, and either nevirapine or efavirenz (based on screening viral load). Baseline characteristics were analyzed in univariate and multivariate regression, to identify risk factors for hepatotoxicity (grade 3 or greater increase in serum aminotransferase levels). The occurrence of early hepatotoxicity was 17% in the nevirapine group and 0% in the efavirenz group and was balanced between the lamivudine and emtricitabine arms. Two subjects died of hepatic failure. Independent risk factors were body-mass index (BMI) <18.5, female sex, serum albumin level <35 g/L, mean corpuscular volume >85 fL, plasma HIV-1 RNA load <20,000 copies/mL, aspartate aminotransferase level <75 IU/L, and lactate dehydrogenase level <164 IU/L. The use of nevirapine in female patients with a low BMI should be discouraged.

Adult↗

PubMed2005

apoE isoforms and measures of anxiety in probable AD patients and Apoe-/- mice.

Increased anxiety may occur in up to 70% of AD patients during the course of their illness. Here we show that human apoE isoforms, which differ in AD risk, have differential effects on measures of anxiety in adult Apoe-/- male mice expressing human apoE3 or apoE4 in their brains and male probable AD (PRAD) patients. Compared with wild-type mice, Apoe-/- mice without human apoE or with apoE4, but not apoE3, showed increased measures of anxiety. These behavioral alterations were associated with reduced microtubule-associated protein 2-positive neuronal dendrites in the central nucleus of the amygdala. Consistent with the mouse data, male and female PRAD patients with epsilon4/epsilon4 showed higher anxiety scores than those with epsilon3/epsilon3. We conclude that human apoE isoforms have differential effects on measures of anxiety.

Aged↗

PubMed2004

Gene expression profiles of transcripts in amyloid precursor protein transgenic mice: up-regulation of mitochondrial metabolism and apoptotic genes is an early cellular change in Alzheimer's disease.

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by the impairment of cognitive functions and by beta amyloid (Abeta) plaques in the cerebral cortex and the hippocampus. Our objective was to determine genes that are critical for cellular changes in AD progression, with particular emphasis on changes early in disease progression. We investigated an established amyloid precursor protein (APP) transgenic mouse model (the Tg2576 mouse model) for gene expression profiles at three stages of disease progression: long before (2 months of age), immediately before (5 months) and after (18 months) the appearance of Abeta plaques. Using cDNA microarray techniques, we measured mRNA levels in 11 283 cDNA clones from the cerebral cortex of Tg2576 mice and age-matched wild-type (WT) mice at each of the three time points. This gene expression analysis revealed that the genes related to mitochondrial energy metabolism and apoptosis were up-regulated in 2-month-old Tg2576 mice and that the same genes were up-regulated at 5 and 18 months of age. These microarray results were confirmed using northern blot analysis. Results from in situ hybridization of mitochondrial genes-ATPase-6, heat-shock protein 86 and programmed cell death gene 8-suggest that the granule cells of the hippocampal dentate gyrus and the pyramidal neurons in the hippocampus and the cerebral cortex are up-regulated in Tg2576 mice compared with WT mice. Results from double-labeling in situ hybridization suggest that in Tg2576 mice only selective, over-expressed neurons with the mitochondrial gene ATPase-6 undergo oxidative damage. These results, therefore, suggest that mitochondrial energy metabolism is impaired by the expression of mutant APP and/or Abeta, and that the up-regulation of mitochondrial genes is a compensatory response. These findings have important implications for understanding the mechanism of Abeta toxicity in AD and for developing therapeutic strategies for AD.

Adenine↗

PubMed2004

Absence of sustained hyperlactatemia in HIV-infected patients with risk factors for mitochondrial toxicity.

BACKGROUND: The prevalence of asymptomatic hyperlactatemia among HIV-infected individuals has been reported to be 4% to 36%. This variability may reflect differences in the definition of and risk factors for hyperlactatemia and/or techniques for venous lactate collection. METHODS: We examined the prevalence of elevated venous lactate collected in accordance with Adult AIDS Clinical Trials Group (AACTG) guidelines among HIV-infected and nucleoside analogue-treated subjects with risk factors associated with hyperlactatemia. Sustained hyperlactatemia was defined as 2 consecutive levels >or=1.5 but or=2 risk factors, with 11% having >4 risk factors. The median entry venous lactate level was 1.2 mmol/L (range: 0.7-5.1 mmol/L). Two subjects had a lactate level >1.5 times the ULN: 1 with a value of 2.1 times the ULN at entry and a week 2 level of 1.2 times the ULN and a second subject with a week 2 value of 1.9 times the ULN but an entry level of 1.4 times the ULN. The latter subject developed symptomatic lactic acidosis 3 weeks following study discontinuation. CONCLUSIONS: Sustained asymptomatic hyperlactatemia among subjects with risk factors associated with hyperlactatemia was not observed when venous lactate was measured in a standardized fashion. One case of hyperlactatemia that evolved into symptomatic lactic acidosis was diagnosed soon after the completion of the study, however. Our findings indicate that asymptomatic hyperlactatemia is either very rare or an artifact of collection technique.

Adolescent↗

PubMed2003

Cerebrospinal fluid tau and beta-amyloid: how well do these biomarkers reflect autopsy-confirmed dementia diagnoses?

BACKGROUND: Tau and beta-amyloid (Abeta) are proposed diagnostic biomarkers for Alzheimer disease (AD). Previous studies report their relationship to clinical diagnoses of AD and other dementias. To understand their value as predictors of disease-specific pathology, levels determined during life must be correlated with definitive diagnoses in mixed dementia groups and cognitively normal subjects. OBJECTIVES: To correlate antemortem cerebrospinal fluid (CSF) tau and Abeta levels with definitive dementia diagnosis in a diverse group of patients; to calculate statistics for CSF tau and Abeta. DESIGN: Prospective study. SETTING: Ten clinics experienced in the diagnosis of neurodegenerative dementias. Patients One hundred six patients with dementia and 4 cognitively normal subjects with a definitive diagnosis, and 69 clinically diagnosed cognitively normal subjects. MAIN OUTCOME MEASURES: Correlation of CSF tau and Abeta with final diagnosis. RESULTS: Mean tau level was 612 pg/mL for the 74 patients with AD, 272 pg/mL for 10 patients with frontal dementia, 282 pg/mL for 3 patients with dementia with Lewy bodies, and 140 pg/mL for 73 cognitively normal control subjects. Tau was less than 334 pg/mL for 20 patients with AD. Abeta42 was reduced in patients with AD (61 fmol/mL) compared with patients with frontal dementia (133 fmol/mL) and control subjects (109 fmol/mL), but not compared with patients with dementia with Lewy bodies (14 fmol/mL) or prion disease (60 fmol/mL). CONCLUSIONS: Elevated CSF tau levels are associated with AD pathology and can help discriminate AD from other dementing disorders. However, some patients with AD have a level less than the mean +/- 2 SDs of the cognitively normal cohort.

Adult↗

PubMed2003

Inflammation and cerebral amyloidosis are disconnected in an animal model of Alzheimer's disease.

The hypothesis that inflammation and beta amyloid deposition are causally linked in Alzheimer's disease (AD) was tested in a transgenic mouse model. Untreated beta amyloid plaque-bearing Tg2576 mice did not differ from wild type animals in brain levels of most inflammatory mediators. Indomethacin treatment suppressed brain levels of prostaglandins by 90%, but reduced hippocampal beta amyloid by only 20%, with no effect on cortical beta amyloid. The discordant effects on beta amyloid and cyclooxygenase (COX) suggest that these effects of nonsteroidal anti-inflammatory drugs (NSAIDs) are not causally linked. Further evidence against a causal relationship is seen in an unexpected trend to lower levels of beta amyloid after an inflammatory stimulus [lipopolysaccharide (LPS)].

Alzheimer Disease↗

PubMed2003

Antioxidants in Alzheimer's disease-vitamin C delivery to a demanding brain.

Levels of several antioxidants and related markers were measured in cerebrospinal fluid (CSF) and plasma of 10 Alzheimer's disease (AD) patients and 10 controls. Daily dosage of vitamin C was significantly correlated with both plasma (R=0.662; p=0.0015) and CSF level (R=0.639, p=0.0024). Plasma and CSF vitamin C levels were also highly correlated R=0.793, p<0.0001). Similarly, daily dosage of Vitamin E was significantly correlated with plasma vitamin E (R=0.681; p=0.0009) and showed a trend toward correlation with CSF vitamin E (R=0.422, p=0.06). There were no significant differences between groups in absolute CSF or plasma levels of any analyte. However, the CSF: plasma ratio of vitamin C was significantly greater in the AD patients compared to the controls (p=0.048). In a subset of AD patients, hippocampal volume was significantly correlated with plasma (R2=0.833; p=0.004) and CSF (R2 =0.603; p=0.04) vitamin C levels, and inversely correlated with CSF:plasma vitamin C ratio (R2 =0.717; p=0.016). We conclude that oral vitamin C supplements are delivered to the brain, and speculate that the increased CSF: plasma ratio of vitamin C in AD reflects increased antioxidant consumption by the AD brain.

Aged↗

PubMedDate not supplied

Vascular dementia.

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Alzheimer Disease↗