Citations

ABSTRACTIsoniazid (INH), a front-line antituberculosis agent, is activated by mycobacterial catalase-peroxidase KatG, converting INH into bactericidal reactive species. Here we investigated the requirements and the pathway of nitric oxide (NO˙) generation during oxidative activation of INH byMycobacterium tuberculosisKatG in vitro. We also provide in vivo evidence that INH-derived NO˙ can inhibit key mycobacterial respiratory enzymes, which may contribute to the overall antimycobacterial action of INH.

ABSTRACTIsonicotinic acid hydrazide (INH) is a frontline antituberculosis agent. Once taken up byMycobacterium tuberculosis, INH requires activation by the catalase-peroxidase KatG, converting INH from its prodrug form into a range of bactericidal reactive species. Here we used15N-labeled INH together with electron paramagnetic resonance spin trapping techniques to demonstrate that nitric oxide (NO˙) is generated from oxidation at the hydrazide nitrogens during the activation of INH byM. tuberculosisKatG. We also observed that a specific scavenger of NO˙ provided protection against the antimycobacterial activity of INH in bacterial culture. No significant increases in mycobacterial protein nitration were detected, suggesting that NO˙ and not peroxynitrite, a nitrating metabolite of NO·, is involved in antimycobacterial action. In conclusion, INH-derived NO·has biological activity, which directly contributes to the antimycobacterial action of INH.

Purpose Atypical teratoid/rhabdoid tumor (AT/RT) of the CNS is an extremely rare and aggressive tumor of early childhood. The poor outcome with conventional infant brain tumor therapy has resulted in a lack of clear treatment guidelines. A registry has been established to create an outcomes database and to facilitate biology studies for this tumor. Materials and Methods A standardized data sheet was provided to treating physicians listing the reports that were to be sent to the registry for abstraction. Follow-up information was sought twice yearly. Results Information was complete for 42 patients. Median age at diagnosis was 24 months. Nine patients (21%) had disseminated disease at diagnosis. Sixteen tumors were infratentorial; 26 were supratentorial. Twenty patients (48%) received a primary complete resection. Primary therapy included chemotherapy in all patients, radiotherapy in 13 patients (31%), stem-cell rescue in 13 patients (31%), and intrathecal chemotherapy in 16 patients (38%). Recurrent or progressive disease was reported in nine and 19 patients, respectively. Twenty-seven patients (64%) are dead of disease (3 to 62 months from diagnosis) and one patient died of toxicity. Fourteen patients (33%) show no evidence of disease (9.5 to 96 months from diagnosis). The median survival is 16.75 months and the median event-free survival is 10 months. Conclusion Aggressive therapy has prolonged the natural history in a subset of children. Prospective multi-institutional and national clinical trials designed specifically for AT/RT are needed. Enrollment onto the AT/RT registry should be continued.

The pathogenic mechanisms by which physical exercise influences atherosclerotic lesion formation remain poorly understood. Because vigorous physical training increases oxidative stress, this study tested the hypothesis that graduated and moderate physical exercise together with metabolic intervention ( l -arginine and antioxidants) may contribute to increased vascular protection. Exercise training in mice was induced by graduated swimming. In hypercholesterolemic male mice on an atherogenic high-cholesterol diet, graduated and moderate exercise lowered plasma cholesterol and decreased atherosclerotic lesions compared with sedentary control mice. Antioxidants (1.0% vitamin E added to the chow and 0.05% vitamin C added to the drinking water) and l -arginine (6% in drinking water) supplementation to exercising hypercholesterolemic mice further and synergistically reduced atherosclerosis compared with untreated exercised mice. Arterial oxidation-specific epitopes and systemic oxidative stress were reduced by metabolic intervention. Graduated chronic exercise elicited an increase in production of nitric oxide through increased endothelial nitric oxide synthase expression and ameliorated scavenger activities. Thus, metabolic intervention with l -arginine and antioxidants together with graduated and moderate exercise training reduce atherosclerotic lesion formation.

Few studies have investigated whether ethnic groups differ in the prevalence of peripheral arterial disease (PAD). We compared the distribution of the ankle-brachial index (ABI), a measure of PAD, between African Americans and non-Hispanic white individuals. Subjects (n = 931) belonged to the Genetic Epidemiology Network of Arteriopathy (GENOA) study, a community-based study of hypertensive sibships, and included 453 African Americans from Jackson, Mississipi (mean age 72 6 years, 69% women) and 478 non-Hispanic white individuals from Rochester, Minnesota (mean age 58 7 years, 64% women). ABI was determined at two sites in each lower extremity and the lowest of four indices was used in the analyses. PAD was defined as an ABI of 0.95. Information about conventional risk factors was derived from interviews and from blood samples drawn at the study visit. The prevalence of diabetes and hypertension was significantly higher in African Americans than in non-Hispanic white individuals. After adjusting for age, African American subjects had a lower mean ABI (women 0.97 vs 1.04, p < 0.001; men 0.96 vs 1.12, p < 0.001) and a greater prevalence of PAD (women 34% vs 22%, p = 0.010; men 33% vs 11%, p < 0.001) than their non-Hispanic white counterparts. In multiple regression analyses, African American ethnicity was a predictor of a lower ABI and the presence of PAD in each sex after adjusting for age and other conventional risk factors. In conclusion, the lower ABI and greater prevalence of PAD in African Americans than in non-Hispanic white individuals is not explained by differences in conventional risk factors. Identifying additional ‘novel’ risk factors that account for the ethnic differences in PAD is an important next step towards understanding why such differences exist and developing more effective strategies to reduce the burden of PAD.

Background and Purpose— Hypertension is an important risk factor for stroke, and the 2 diseases may share susceptibility genes in common. We sought to identify genomic regions influencing susceptibility to both hypertension and stroke. Subjects and Methods— Genome-wide linkage scans were performed in samples of 338 white and 265 black hypertensive sibships recruited by the Genetic Epidemiology Network of Arteriopathy Study of the NHLBI Family Blood Pressure Program (FBPP). The hypertensive sibships were stratified by positive (+FH) or negative (−FH) family history of stroke. Genome-wide scans were repeated in each stratum, and the results were compared within each ethnic group by a regression-based analysis of heterogeneity. Results— In whites, the best evidence for linkage was found on chromosome 16 in the unstratified sample of hypertensive sibpairs (logarithm of odds [LOD]=1.85 at 71 cM). In blacks, the best evidence for linkage was found on chromosome 2 in the unstratified sample of hypertensive sibpairs (LOD=1.95 at 230 cM). Additional evidence for linkage (LOD ≥1.5) was observed among white hypertensive sibpairs with a −FH on chromosome 13 and among black hypertensive sibpairs with a +FH of stroke on chromosome 19. Conclusions— Significant evidence for linkage heterogeneity among hypertensive sibpairs stratified by family history of stroke suggests the presence of genes influencing susceptibility to both hypertension and stroke on chromosomes 13 (whites) and 19 (blacks). Although no significant evidence of heterogeneity was observed on chromosome 16 in whites and chromosome 2 in blacks, these chromosomes do provide evidence of linkage to hypertension.

Abstract Background Perineal wounds, created at the time of extended resection for locally advanced malignancy and following chemoradiation, are at risk of serious complications. Methods To determine whether immediate myocutaneous flap closure prevents complications, 57 patients treated with multimodality therapy and proctectomy (35 perineal wounds) or sacrectomy (22 posterior wounds) were studied. Patients were categorized according to whether they underwent primary skin and pelvic closure (group 1; n = 20); primary skin and omental pelvic closure (group 2; n = 24); or immediate myocutaneous flap closure (group 3; n = 13). Results Groups were similar with respect to age and sex; however, group 1 had more primary tumours and required less radical surgery and chemoirradiation than groups 2 and 3. Groups 1 and 2 experienced more complications overall (eight of 20, nine of 24 and three of 13 patients in groups 1, 2 and 3 respectively), more acute wound complications (seven of 20, nine of 24 and two of 13), delayed wound healing (three of 20, six of 24 and one of 13) and more reoperations for perineal wound problems (five of 20, seven of 24 and zero of 13). Patients in group 2 had a significantly longer hospital stay than those in group 1. Flap closure (group 3) did not increase the length of stay. The routine use of primary flap closure reduced overall wound complications (eight of 31 versus ten of 26 patients) and length of hospitalization (13 versus 17 days). Conclusion Complete wound healing was achieved in all patients; however, immediate myocutaneous flap closure reduced the need for readmission and reoperation.

Abstract We examined the accuracy of preoperative assessment in predicting postoperative pulmonary risk in a prospective cohort of 272 consecutive patients referred for evaluation before nonthoracic surgery. Outcomes were assessed by an independent investigator who was blinded to the preoperative data. There were 22 (8%) postoperative pulmonary complications. Statistically significant predictors of pulmonary complications (all p ≤ 0.005) were as follows: hypercapnea of 45 mm Hg or more (odds ratio, 61.0), a FVC of less than 1.5 L/minute (odds ratio, 11.1), a maximal laryngeal height of 4 cm or less (odds ratio, 6.9), a forced expiratory time of 9 seconds or more (odds ratio, 5.7), smoking of 40 pack-years or more (odds ratio, 5.7), and a body mass index of 30 or more (odds ratio, 4.1). Multiple regression analyses revealed three preoperative clinical factors that are independently associated with pulmonary complications: an age of 65 years or more (odds ratio, 1.8; p = 0.02), smoking of 40 pack-years or more (odds ratio, 1.9; p = 0.02), and maximum laryngeal height of 4 cm or less (odds ratio, 2.0; p = 0.007). Thus, preoperative factors can identify those patients referred to pulmonologists or internists who are at increased risk for pulmonary complications after nonthoracic surgery.