Neural response to working memory demand predicts neurocognitive deficits in HIV.

Human immunodeficiency virus (HIV) continues to have adverse effects on cognition and the brain in many infected people, despite a reduced incidence of HIV-associated dementia with combined antiretroviral therapy (cART). Working memory is often affected, along with attention, executive control, and cognitive processing speed. Verbal working memory (VWM) requires the interaction of each of the cognitive component processes along with a phonological loop for verbal repetition and rehearsal. HIV-related functional brain response abnormalities during VWM are evident in functional MRI (fMRI), though the neural substrate underlying these neurocognitive deficits is not well understood. The current study addressed this by comparing 24 HIV+ to 27 demographically matched HIV-seronegative (HIV-) adults with respect to fMRI activation on a VWM paradigm (n-back) relative to performance on two standardized tests of executive control, attention and processing speed (Stroop and Trail Making A-B). As expected, the HIV+ group had deficits on these neurocognitive tests compared to HIV- controls, and also differed in neural response on fMRI relative to neuropsychological performance. Reduced activation in VWM task-related brain regions on the 2-back was associated with Stroop interference deficits in HIV+ but not with either Trail Making A or B performance. Activation of the posterior cingulate cortex (PCC) of the default mode network during rest was associated with Hopkins Verbal Learning Test-2 (HVLT-2) learning in HIV+. These effects were not observed in the HIV- controls. Reduced dynamic range of neural response was also evident in HIV+ adults when activation on the 2-back condition was compared to the extent of activation of the default mode network during periods of rest. Neural dynamic range was associated with both Stroop and HVLT-2 performance. These findings provide evidence that HIV-associated alterations in neural activation induced by VWM demands and during rest differentially predict executive-attention and verbal learning deficits. That the Stroop, but not Trail Making was associated with VWM activation suggests that attentional regulation difficulties in suppressing interference and/or conflict regulation are a component of working memory deficits in HIV+ adults. Alterations in neural dynamic range may be a useful index of the impact of HIV on functional brain response and as a fMRI metric in predicting cognitive outcomes.

Neural dysregulation during a working memory task in human immunodeficiency virus-seropositive and hepatitis C coinfected individuals.

Cognitive and functional neural correlates of human immunodeficiency virus (HIV) are only partially understood at present. Variability in neural response, which has been noted in the literature, may relate to clinical factors associated with HIV, including time since HIV diagnosis, CD4 count and nadir, HIV viral load, and comorbid infectious processes, especially hepatitis C. The present investigation evaluated working memory-related functional neural activation in 26 HIV+ participants, 28 demographically matched HIV-seronegative individuals, and 8 HIV+ individuals with hepatitis C coinfection. Analyses examined impact of HIV infection duration, CD4 count and nadir, HIV viral load, and hepatitis C serostatus. Results showed that HIV-seronegative participants had fastest reaction times, and during the working memory task, HIV+ participants with hepatitis C coinfection showed strongest bias toward commission errors; however, signal detection (i.e., overall task performance) was equivalent across groups. Functional magnetic resonance imaging (fMRI) results showed HIV-related greater activation to an easier vigilance task and HIV-related lower activation to a more difficult working memory task, consistent with reduced cognitive reserve. Hepatitis C coinfection related to diffuse neural dysregulation. Correlational analyses suggested relationships of increasingly severe disease with poorer functioning in brain regions linked to error monitoring and attention regulation.

Peripheral and visceral fat changes following a treatment switch to a non-thymidine analogue or a nucleoside-sparing regimen in HIV-infected subjects with peripheral lipoatrophy: results of ACTG A5110.

BACKGROUND: Switching a thymidine analogue to a non-thymidine analogue or changing to a nucleoside-sparing regimen has been shown to partially reverse peripheral lipoatrophy. The current study evaluated both approaches. METHODS: Subjects at 15 AIDS Clinical Trial Group sites receiving thymidine analogue stavudine- or zidovudine-containing regimens with plasma HIV RNA < or =500 copies/mL and lipoatrophy were prospectively randomized to: (i) switch the thymidine analogue to abacavir; (ii) discontinue all antiretrovirals and switch to lopinavir/ritonavir plus nevirapine (LPV/r+NVP); or (iii) delay switching for 24 weeks (ClinicalTrials.gov identifier: NCT00028314). Single-slice computer tomography of mid-thigh and abdominal fat and metabolic and virological/immunological parameters were measured at baseline and weeks 24 and 48. RESULTS: Among the 101 patients enrolled, there were significant subcutaneous thigh fat and subcutaneous abdominal tissue (SAT) increases over time and decreases in visceral adipose tissue to total adipose tissue (VAT:TAT) ratios for both interventions, and a decrease in VAT for abacavir. CD4 increased in the LPV/r+NVP arm. LPV/r+NVP had a significantly shorter time to grade 3 or higher toxicity (P = 0.007), but discontinuation rates were similar. Glucose levels did not change, but insulin decreased in the LPV/r+NVP arm. Lipids tended to increase in the LPV/r+NVP arm. CONCLUSIONS: Switching stavudine or zidovudine to a non-thymidine analogue or changing to a nucleoside reverse transcriptase inhibitor-sparing regimen is associated with qualitatively similar improvements in thigh fat, SAT and VAT:TAT ratio at 48 weeks. Abacavir also resulted in VAT reductions and LPV/r+NVP resulted in CD4 count increases.

Epidemiology of cervical cancer by cell type.

A multicenter case-control study of 481 invasive cervical cancer patients and 801 population controls enabled comparison of risk factors for squamous cell tumors (n = 418), adenosquamous cancers (n = 23), and adenocarcinomas (n = 40). The epidemiology of the squamous cell tumors resembled that found in other studies, with the major risk factors being absence of Pap smear screening (relative risk = 3.6 to 4.8 for those not screened within 5 yr), multiple sexual partners (relative risk = 2.9 for over ten partners), and history of genital infections or sores (relative risk = 2.3). Although based on small numbers, adenosquamous tumors appeared to share some of these risk factors, notably number of sexual partners, years since last Pap smear, and level of education. Adenocarcinomas were not similarly affected, although sexual practices were marginally predictive. Obesity increased the risk of adenocarcinoma, but no other similarities to endometrial adenocarcinoma were observed. Smoking was a significant predictor of squamous cell tumors but did not affect adenocarcinomas. Extended use of oral contraceptives was a risk factor for all tumor types, especially adenocarcinoma, and a familial tendency to cervical cancer was also observed for all cell types.

Role of nitric oxide in the cerebellar degeneration during methylmercury intoxication.

To investigate the role of nitric oxide in the cerebellar degeneration during methylmercury intoxication, interaction of the change in nitric oxide synthase activity and degeneration of the granular layer neurons was examined in rats after methylmercury administration. Both reduced nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase and anti-nitric oxide synthase antibody staining, and measurement of glutamate, and nitrite and nitrate levels in the cerebrospinal fluid were performed after oral administration of 5 mg/kg of methylmercury for 12 days. Nitric oxide synthase activity in the cerebellum was also assayed by monitoring the conversion of arginine to citrulline. Methylmercury levels in the blood and the cerebellum gradually increased up to day 13 after the initial methylmercury administration, and neurological disturbances, such as hindleg crossing and abnormal gait, were observed from day 17 after administration. Although a significant decrease in the number of granular layer neurons was recognized at day 84, no such decrease either in NADPH-diaphorase or anti-nitric oxide synthase antibody positive neurons was seen. Glutamate levels in the cerebrospinal fluid transiently increased at day 9 and finally decreased at day 84. Also a transient increase in both nitrite and nitrate levels in the cerebrospinal fluid and nitric oxide synthase activity in the cerebellum was seen prior to the start of degeneration of the granular layer neurons. These results suggest that nitric oxide may play an important role in the degeneration process of the granular layer neurons during methylmercury intoxication.

Enhancement of AA-amyloid formation in mice by transthyretin amyloid fragments and polyethylene glycol.

The mechanism behind amyloid formation is unknown in all types of amyloidosis. Several substances can enhance amyloid formation in animal experiments. To induce secondary systemic amyloid (AA-type amyloid) formation, we injected silver nitrate into mice together with either amyloid fibrils obtained from patients with familial polyneuropathy (FAP) type I or polyethylene glycol (PEG). Mice injected with silver nitrate only served as controls. Amyloid deposits were detectable at day 3 in animals injected with amyloid fibrils and in those injected with PEG, whereas in control mice, deposits were not noted before day 12. Our results indicate that amyloid fibrils from FAP patients and even a non-sulfate containing polysaccharide (PEG) have the potential to act as amyloid-enhancing factors.

Down regulation of a harmful variant protein by replacement of its normal protein.

To compensate for the hypoprotein and hypoalbuminemia of familial amyloidotic polyneuropathy (FAP) patients, 800 ml of fresh frozen plasma (FFP) was intravenously administered and change in total and variant transthyretin (TTR) levels were measured in the plasma. After injection of FFP, total plasma TTR levels were elevated and variant TTR levels decreased from 24 to 48 h, accompanied by an elevation of plasma total protein, albumin levels and TTR levels. To elucidate the mechanism of this phenomenon, a large amount of purified normal TTR from normal human plasma was intravenously injected in mice and FAP patients. By intravenous injection of 3 mg of the purified TTR to C57Black6, the expression of TTR mRNA decreased from 6 to 24 h post injection, and gradually increased up to 48 h post injection. After injecting 400 mg of normal TTR in each of 3 FAP patients, total plasma TTR levels were elevated and variant TTR levels decreased significantly from 24 to 48 h. These results suggested that down regulation of the harmful protein by replacement of its normal form of the protein occurred by this method. This phenomenon should be applied as the basis for one of the useful methods for decreasing the harmful proteins in the circulation.

Magnetic resonance imaging of heterotaxia in infants.

OBJECTIVES: This study assessed the usefulness and safety of magnetic resonance imaging (MRI) for systematically diagnosing heterotaxia in infants. BACKGROUND: Although it is important to diagnose and treat infants with heterotaxia, which is associated with viscerobronchial cardiovascular anomalies, systematic diagnosis of these anomalies by a single imaging technique is difficult. METHODS: Twenty patients with heterotaxia were evaluated. The infants ranged in age from 21 days to 12 months (average 5.2 months, average body weight 4.3 kg). Electrocardiographically gated MRI was performed by spin echo imaging techniques operating at 0.5 tesla. RESULTS: In all 20 patients, MRI results were sufficient to evaluate these anomalies without serious complications. In 17 patients, neither a spleen nor splenules were detected, but in 3 patients, a polymorphous spleen was visualized. In all 20 patients, bronchial anatomies were clearly visualized (bilateral eparterial bronchi in 14 patients, bilateral hyparterial bronchi in 2 and normal bronchial patterns in 4). Additionally, in a comparison of 149 observations of cardiovascular anatomy by MRI with those by angiography, discrepancies were found in only 10 observations (6.7%). CONCLUSIONS: Magnetic resonance imaging was found to be safe and very useful for the systematic diagnosis of heterotaxia in infants.

Neurocognitive performance enhanced by highly active antiretroviral therapy in HIV-infected women.

OBJECTIVE: To determine whether highly active retroviral therapy (HAART) is associated with better neurocognitive outcome over time among HIV-infected women with severely impaired immune function. METHODS: A semiannual neurocognitive examination on four tasks was administered: Color Trail Making, Controlled Oral Word Association, Grooved Pegboard and Four-Word Learning. This protocol was initiated in the HIV Epidemiological Research study (HERS) study when a woman's CD4 cell count fell to < 100 x 10(6) cells/l. Immune function (CD4), viral load status and depression severity (CESD) were also assessed semi-annually, along with an interview to determine medication intake and illicit drug use. RESULTS: HAART was not available to any participant at the time of enrollment (baseline), while 44% reported taking HAART at their most recent visit (mean duration of HAART 36.3 +/- 12.6 months). HAART-treated women had improved neurocognitive performance compared with those not treated with HAART. Women taking HAART for 18 months or more showed the strongest neurocognitive performance with improved verbal fluency, psychomotor and executive functions. These functions worsened among women not taking HAART. Substance abuse status, severity of depressive symptoms, age and educational level did not influence the HAART treatment effects on neurocognitive performance. Neurocognitive improvements were strongly associated with the magnitude of CD4 cell count increases. CONCLUSIONS: HAART appeared to produce beneficial effect on neurocognitive functioning in HIV-infected women with severely impaired immune systems. Benefits were greatest for women who reported receiving HAART for more than 18 months.

Discordant Human Immunodeficiency Virus Type 1 drug resistance mutations, including K103N, observed in cerebrospinal fluid and plasma.

Discordant resistance mutations were seen in human immunodeficiency virus type 1 (HIV-1) isolated from specimens of blood and cerebrospinal fluid (CSF) obtained from 3 of 6 patients. To our knowledge, this is the first report of HIV-1 isolated from CSF harboring the K103N mutation, which confers resistance to the nonnucleoside reverse-transcriptase inhibitors, and this finding may indicate that virus in the CSF replicates independently from virus in the blood compartment.