Delayed nonmatch-to-sample performance in HIV-seropositive and HIV-seronegative polydrug abusers

Working memory (WM) deficits are common in HIV-seropositive (HIV+) individuals and can be amplified by manipulating a variety of task parameters, such as increasing memory load or information complexity. The authors investigated the role of timing in HIV-associated WM defects by varying the amount of time required to maintain information online while holding memory load and information complexity constant. The authors studied 50 HIV+ and 35 HIV-seronegative (HIV-) polydrug abusers abstinent at testing and well-matched on demographic variables. The HIV- group outperformed the HIV+ group across all stimulus-response time delays. HIV-associated WM defects are not critically dependent on the amount of time stimulus representations must be maintained and might be attributed to impaired encoding or retrieval of stimulus representations.     

Test-retest reliability of the Temperament and Character Inventory in patients with opiate dependence

We examined the test-retest reliability of the Temperament and Character Inventory (TCI) in a clinical sample of 29 inpatients with opiate dependence disorder (DSM-IV). The previously validated French translation of the TCI was administered at baseline and again four weeks later. Intraclass correlation coefficients (ICCs) were used to estimate stability of the TCI over time for the 15 patients who completed the study. For all ICCs, the TCI showed satisfactory to excellent stability across all factors (ICC= 0.66-0.82). Stability was lower for the two temperamental traits of 'persistence' (ICC=0.51) and 'reward dependence' (ICC=0.63), possibly reflecting both clinical instability and measurement errors. These results highlighted the overall stability of the TCI in patients with opiate dependence and provided evidence for the usefulness of this questionnaire, which was originally designed to explore genetic and environmental factors underlying normal and abnormal personality dimensions. Further studies are required to confirm these results on larger clinical samples.     

Neuromagnetic imaging of cortical oscillations accompanying tactile stimulation

We applied a new method of imaging frequency-specific changes in brain activity in humans during a finger brushing task in order to measure changes in cortical rhythms during tactile stimulation. Neuromagnetic recordings were conducted in five subjects using a whole-head MEG system during tactile stimulation of the right index finger, with or without visual feedback, and while viewing another individual's index finger being stimulated. Volumetric images of changes in source power relative to pre-stimulus baseline levels were computed with 2 mm resolution over the entire brain using a minimum-variance beamforming algorithm (synthetic aperture magnetometry). Onset of tactile stimulation produced a brief (200-300 ms) suppression of mu band (8-15 Hz) and beta band (15-30 Hz) cortical activity in the primary somatosensory and primary motor cortex, respectively, followed by a bilateral increase in beta band activity ('beta rebound') in motor cortex. This pattern of suppression/rebound was absent when subjects observed finger brushing or brushing motions without receiving stimulation. In contrast, these conditions resulted in bilateral increases in beta band activity in sensorimotor areas and decreased power in the alpha (8-12 Hz) band in primary visual areas. These results show that spatially filtered MEG provides a useful method for directly imaging the temporal sequence of changes in cortical rhythms during transient tactile stimulation, and provide evidence that observation of tactile input to another individual's hand, or object motion itself, can influence independent rhythmic activity in visual and sensorimotor cortex.     

Association of gephyrin with synaptic and extrasynaptic GABAA receptors varies during development in cultured hippocampal neurons

Several studies have reported extrasynaptic clusters of GABAA receptors in hippocampal neurons. Yet their functional relevance as well as their evolution in relation with gephyrin during synaptogenesis remain unknown. We have analyzed the expression pattern of the main proteins of the GABAergic synapses during synaptogenesis in cultured hippocampal neurons. We found that GABAergic terminals, characterized by VIAAT and GAD-65 expression, differentiated 3 to 7 days after the glutamatergic endings. At the postsynaptic side, the GABAAR- beta3 subunit was first diffuse and then clustered when GABAergic terminals differentiated and gephyrin formed large clusters. Colocalization of these proteins was high and increased with development. At later stages, GABAAR beta3 clusters colocalized with gephyrin at synaptic but also at extrasynaptic sites. GABAAR gamma2 subunits were directly expressed as clusters which were first extrasynaptic and not associated with gephyrin. Subsequently, the GABAAR gamma2 subunits associated with gephyrin at synaptic and/or extrasynaptic sites. Our data indicate that formation of GABAAR gamma2 subunit clusters is gephyrin independent.     

Nutritional factors as predictors of response to radio-chemotherapy and survival in unresectable squamous head and neck carcinoma

BACKGROUND AND PURPOSE: This study sought to evaluate nutritional prognostic factors before treatment in patients with unresectable head and neck cancer treated by concomitant radio-chemotherapy. METHODS AND MATERIALS: Seventy-two consecutive patients were treated. We studied the potential effects of CRP, Alb, preAlb, orosomucoid, weight, weight history, BMI, PINI, OPR and NRI on response to treatment, Event-Free Survival (EFS) and Overall Survival (OS). Effects of potential risk factors on OS and on EFS were analyzed by computing Kaplan-Meier estimates, and curves were compared using the log-rank test. RESULTS: All biological nutritional factors were statistically correlated with the response to radio-chemotherapy. In multivariate analysis, only CRP (p=0.004) remained statistically significant. A statistical correlation was found between Alb and EFS in multivariate analysis (p=0.04). The factors influencing OS in univariate analysis were Alb (p=0.008), CRP (p=0.004), orosomucoid (p=0.01) and NRI (p=0.01), response to radio-chemotherapy (p<0.001) and staging (p=0.04). In multivariate analysis, only the response to radio-chemotherapy (p<0.001) remained significant. CONCLUSIONS: This study illustrates the prognostic value of nutritional status. CRP and Alb may be useful in the assessment of advanced head and neck cancer patients at diagnosis and for stratifying patients taking part in randomized trials.     

Cryptococosis and HIV/AIDS: a review of 21 cases reported in the Tropical Diseases Centre, Ho Chi Minh City (Vietnam)

Cryptococcus neoformans affections during HIV-infection are frequent and serious. The aim of this study was to analyse the epidemiological, clinical, biological and therapeutic characteristics of cryptococcal meningitis in HIV-positive patients, admitted into the Center for Tropical Diseases Ho Chi Minh City (Vietnam), during a 5-month period (May-September 2001). Twenty-one patients (20 men and one woman) were included (identification of C. neoformans from the cerebrospinal fluid). The mean age was 28 years. The majority of patients had been living in Ho Chi Minh City (48%). The use of drugs and unprotected sexual relations were the principal risk factors of HIV-infection. The paucity and the confusion of clinical signs and symptoms, along with a high frequency of meningitis have been analysed. Clinical presentation features included: headache (95%), emaciation (90%), oro-pharyngeal candidiasis (90%), stiff neck (80%), nausea/vomiting (70%), fever (67%), coughing (38%), diarrhoea (33%), skin lesions (5%), convulsion (5%), photophobia (5%), and hemiparesis (5%). The severity of the prognosis was mainly linked to the delay before hospitalization, to the possible association with other opportunistic infections, and to the availability of appropriate treatment.     

Pharmacodynamic equivalence of two flecainide acetate formulations in patients with paroxysmal atrial fibrillation by QRS analysis of ambulatory electrocardiogram

The pharmacodynamic equivalence of flecainide acetate immediate-release (IR) and controlled-release (CR) formulations was assessed from QRS duration in patients currently treated with the IR formulation. Patients were blindly assigned randomly to the IR (100 mg BID, n = 25) or to the CR group (200 mg OD, n = 23). Electrocardiographic parameters were measured at baseline and at week 8 from 24-h Holter monitoring. Mean (SD) normalized flecainide trough plasma concentration (measured 12 h after last intake) at week 8 was 381.3 ng/ml (104.8) with the IR and 381.4 ng/ml (123.8) with the CR formulation. Hodges-Lehmann estimate (95% CI) of the difference between IR and CR for change in QRS duration between baseline and week 8 was 1.6% (-0.1; 3.7), indicating that the formulations were pharmacodynamically equivalent. Median QRS values (102 vs 100.1 ms at baseline; 103.15 vs 99 ms at week 8) as well as first and third quartiles were very similar in both groups. The correlation between QRS duration and RR classes at baseline was highly significant (P < 0.0001). Correlation coefficient at week 8 was statistically significant for > 50% of the patients and was significant in a greater proportion of patients under the IR compared with the CR formulation. Circadian hourly variations of QRS duration as determined by harmonic analysis showed the occurrence of a peak of QRS widening following each intake of the IR, whereas this pattern was not observed with the CR formulation. The latter results are consistent with a greater occurrence of frequency-dependent QRS variations over the 24-h period with the IR compared with the CR formulation.