Prognostic value of the exercise test after myocardial infarction

A stress test performed in the early stage after myocardial infarction enables to evaluate directly or indirectly three of the main prognosis factors: alteration of ventricular function, presence of ventricular arrhythmias, residual ischemia. This test, performed around the 15th day, after previous anti-angina treatment have been discontinued, is only done in the absence of the classic contra-indications. It permits to detect abnormalities: electrical positivity (with or without pain), disorder of the ventricular rhythm, abnormality of the blood pressure profile, low stress level. The predictive value of these abnormalities has been the subject of many studies. Although all the results are not in agreement, each one of these abnormalities seems to carry an increased risk of cardiac occurrences after myocardial infarction. In addition, an early stress test enables to detect pluritroncular coronary lesions with, however, an average sensitivity. Thallium scintigraphy in conjunction with a stress test improves, however, the performances of this test. The advantage of an early stress test is the rapid screening of high risk patients who should benefit from additional exploratory measures and possibly of myocardial revascularization procedures.     

Non-participation bias in unlinked anonymous HIV-prevalence surveys in England and Wales.

The objective was to assess the potential bias in unlinked anonymous HIV-seroprevalence surveys from objections to specimens being included. Objection rates in seroprevalence surveys were examined. Statistically large clusters of objections were considered to be the result of health care worker behaviour, and were disregarded. Underlying objection rates were estimated from remaining data and compared to seroprevalence. Overall objection rates approached or exceeded seroprevalence in many participating centres. However, underlying objection rates declined with time while prevalences were generally unchanging. Also, underlying rates correlated poorly with observed seroprevalences. Findings were therefore consistent with processes producing the clusters of objections and underlying objection rates independently of serostatus of individuals. Although national seroprevalence estimates produced by the surveys are reasonably free from objection bias, regional seroprevalence estimates outside London remain vulnerable to bias as a result of some centres returning data whose quality cannot be guaranteed.     

In vivo MR measurements of regional arterial and venous blood volume fractions in intact rat brain.

In vivo measurement of cerebral arterial and venous volume fractions is important to the understanding of brain physiology and function. By using an intravascular perfluorocarbon and 19F NMR at 4.7 T, regional arterial and venous volume fractions from an intact rat brain were resolved based on the pseudodiffusion coefficients, which were (33 +/- 7) x 10(-3) and (0.45 +/- 0.13) x 10(-3) mm(2)/sec (mean +/- SD, n = 7) for the fast- and slow-moving component, respectively. By exploiting the linear dependence of the perfluorocarbon 19F 1/T1 on the dissolved paramagnetic oxygen concentration, combined inversion-recovery and diffusion measurements were made to correlate the short T1 (high-oxygenation) component with the fast-moving component and the long T1 (low-oxygenation) component with the slow-moving component. The arterial blood volume fraction was 29 +/- 7% of the total cerebral blood volume. Finally, experiments were performed in which different oxygen concentrations were inhaled to validate this technique.     

Antibody‐mediated rejection in pediatric small bowel transplantation: Capillaritis is a major determinant of C4d positivity in intestinal transplant biopsies

The diagnostic criteria for antibody‐mediated rejection (ABMR) after small bowel transplantation (SBT) are not clearly defined, although the presence of donor‐specific antibodies (DSAs) has been reported to be deleterious for graft survival. We aimed to determine the incidence and prognostic value of DSAs and C4d in pediatric SBT and to identify the histopathologic features associated with C4d positivity. We studied all intestinal biopsies (IBx) obtained in the first year posttransplantation (N = 345) in a prospective cohort of 23 children. DSAs and their capacity to fix C1q were identified by using Luminex technology. Eighteen patients (78%) had DSAs, and 9 had the capacity to fix C1q. Seventy‐eight IBx (22.6%) were C4d positive. The independent determinants of C4d positivity were capillaritis grades 2 and 3 (odds ratio [OR] 4.02, P = .047 and OR 5.17, P = .003, respectively), mucosal erosion/ulceration (OR 2.8, P = .019), lamina propria inflammation grades 1 and 2/3 (OR 1.95, P = .043 and OR 3.1, P = .016, respectively), and chorion edema (OR 2.16, P = .028). Complement‐fixing DSAs and repeated C4d‐positive IBx were associated with poor outcome (P = .021 and P = .001, respectively). Our results support that capillaritis should be considered as a feature of ABMR in SBT and identify C1q‐fixing DSAs and repeated C4d positivity as potential markers of poor outcome.     

Rapid decline in acute stimulation thresholds with steroid-eluting active-fixation pacing leads

BACKGROUND AND AIM: There is an increasing use of active-fixation leads for cardiac pacing, yet concerns remain regarding initial high stimulation thresholds. The aim was to perform a detailed analysis of pacing parameters at the time of implantation to determine when lead repositioning should be considered. METHODS: We performed a prospective observational study of consecutive new pacemaker implants. Detailed analysis of pacing parameters was collected at 2-minute intervals for 10 minutes, and at day 1 and week 8 following implant. RESULTS: Ninety-four patients underwent implantation of 79 dual-chamber and 15 single-chamber pacemakers using active-fixation leads in both chambers. An initial threshold of >1 V was demonstrated in 45/94 (48%) ventricular leads (mean threshold 1.5 +/- 0.3 V). This declined rapidly to 0.9 +/- 0.3 V at 4 minutes (P < 0.01), 0.7 +/- 0.3 V at 10 minutes (P < 0.01), and 0.6 +/- 0.3 V at day 1 (P < 0.01). At day 1, 43/45 leads were <1 V. There were 79 atrial leads. An initial threshold of >1 V (mean 1.7 +/- 0.6 V) was demonstrated in 41/79 (52%) leads falling significantly to 1.1 +/- 0.5 V at 4 minutes (P < 0.01), 0.9 +/- 0.4 V at 10 minutes (P < 0.01), and 0.6 +/- 0.2 V at day 1 (P < 0.01). At 10 minutes, 32 of 41 leads demonstrated a threshold of <1 V with all leads <1 V at day 1. Thresholds were maintained medium term. CONCLUSIONS: Active-fixation leads are commonly associated with initially high thresholds that fall rapidly. An initial threshold of 2 V should be provisionally accepted and retested at 4 minutes. The majority will have a threshold of <1 V the following day. A failure of a high threshold to decline at 4 minutes requires lead repositioning.     

Serum adiponectin and metabolic parameters in HIV-1-infected patients after substitution of nevirapine for protease inhibitors

BACKGROUND: In the context of HIV infection and antiretroviral therapy, adiponectin concentrations have been shown to be related to lipodystrophy, metabolic alterations and HIV-protease inhibitor (PI) use. The replacement of PI by nevirapine has improved the lipid profile of patients under antiretroviral therapy. The aim of the present study was to examine whether adiponectin concentration or insulin sensitivity level correlate with the modifications of lipid parameters after the switch of PI by nevirapine. MATERIAL AND METHODS: The evolution of metabolic parameters before and after 6 months of substitution of nevirapine for protease inhibitors was evaluated in a cohort of 55 HIV-1 infected patients. Adiponectin concentration, insulin sensitivity, lipid profile, cholesterol ester transfer protein (CETP) mass concentration and triglyceride enrichment of HDL were determined before and after the replacement of PI by nevirapine. Insulin sensitivity was evaluated by the HOMA model assessment. RESULTS: Twenty-four weeks of treatment with nevirapine improved significantly the lipid profile with a significant reduction of apoB (from 0.98 to 0.92 g L(-1); P = 0.005) and triglyceride (from 2.02 to 1.66 mmol L(-1); P = 0.02). HDL cholesterol and apoA1 increased significantly (from 0.99 to 1.19 mmol L(-1); P = 0.001 and from 1.40 to 1.57 g L(-1); P < 0.001, respectively). The triglyceride enrichment of HDL significantly decreased after the replacement of PI by nevirapine (from 0.248 +/- 0.092 to 0.213 +/- 0.093; P = 0.003). At baseline, and after 24 weeks of nevirapine treatment, we observed significant correlations between adiponectin level and lipid parameters [(HDL-cholesterol (r = 0.66, P = 0.001 and r = 0.69, P = 0.001); triglycerides (r = -0.42, P = 0.002 and r = -0.57, P = 0.001), and triglyceride enrichment of HDL (r = -0.43, P = 0.005 and r = -0.53, P = 0.005)]. Twenty-four weeks of treatment with nevirapine did not significantly change adiponectin concentrations (from 984 to 1086 micro g L(-1), P = 0.22), CETP mass and insulin sensitivity. CONCLUSION: This study shows that even though a strong correlation was found between adiponectin and some metabolic parameters at baseline and after 24 weeks of treatment by nevirapine, the improvement of lipid profile observed after the replacement of PI by nevirapine was not in relation to the change of plasma adiponectin concentration. The significant decrease of triglyceride enrichment of HDL after the replacement of PI by nevirapine probably leads to a decreased catabolism of HDL lipoprotein, and consequently explains the increase of plasma HDL concentration observed in this study.     

Heterogeneity of hepatitis B virus genotype D in Japan

OBJECTIVE: Hepatitis B virus (HBV) genotypes B and C are predominant in Japan. Previously, we reported that approximately 9% of HBV carriers in the Ehime area of western Japan were infected with genotype D (HBV/D) and their sequences closely related. Recently, serum samples from 3 patients with chronic HBV/D infections living in Tokyo and the surrounding area became available for testing. The purpose of this study was to determine whether the HBV/D isolates from these different areas of Japan are closely related. METHODS: Of the 3 Tokyo area patients infected with HBV/D, 2 had chronic hepatitis, and 1 had hemophilia with a history of frequent coagulation factor injections. The complete HBV/D genome sequences of each were determined, and compared with those of subjects from the Ehime area. RESULTS: All 3 HBV/D sequences had a genomic length of 3,182 bases, and the hepatitis B surface antigen subtype was ayw3. Phylogenetic analysis revealed that the 1 of the HBV/D isolates was closely related to the isolates from Ehime Prefecture, while 1 was similar and 1 was clearly distinct. CONCLUSION: Our results indicate that HBV/D infections in Japan are heterogeneous.