Recurrence of atrial tachyarrhythmias in implantable cardioverter-defibrillator recipients

BACKGROUND: Because the natural history of atrial tachyarrhythmia (AT) is not known in patients with implantable cardioverter-defibrillators (ICDs) but without device-based atrial therapies, we aimed to describe the characteristics and recurrence of AT in such patients. METHODS: In this multicenter trial, 269 patients with standard indications for ICD placement and 2 episodes of AT in the preceding year received a dual-chamber ICD capable of logging AT. Patients were randomly assigned to 3-month periods of atrial therapies "on" or "off." This analysis considered only the 118 patients with atrial therapies programmed off at ICD placement. RESULTS: Fifty-eight patients (49%) had at least 1 AT episode longer than 1 minute, and 21 (18%) had at least 1 prolonged episode (>24 hours). The median episode frequency for each patient (episodes per month) was 1.8 episodes longer than 1 minute, 0.8 longer than 1 hour, and 0 longer than 24 hours. The median AT burden was 12.2 hours per month. CONCLUSIONS: Patients with standard ICD indications and history of AT have infrequent episodes, frequent short episodes, or prolonged episodes of AT-atrial fibrillation. However, the clinical characteristics examined did not distinguish among the groups. Improved diagnostic tools may help identify patients at risk for development of AT, thereby allowing specific therapies to be targeted to each group of patients.     

The effect of malignant disease on peritoneal healing in the rat

A study of the healing of peritoneal defects in the rat in the presence of the Walker 256 tumour has been made. The healing process was investigated histologically, by autoradiography, and by hydroxyproline estimation of the healing peritoneal wound. There was no difference in the rates or quality of the healing process in the control or tumour bearing animals.     

Diagnostic modalities in diagnosis of adult patients with acute abdominal pain

In order to provide an accurate diagnosis and management strategy for adult patients with acute abdominal pain and peritoneal irritation, it is important to understand the value of various forms of diagnostics modalities. History, physical examination and laboratory results can generally differentiate between an acutely serious and a less serious abdominal problem. Patients with acute abdominal pain and no increase in either the leukocyte count or the concentration of C-reactive protein should be re-evaluated after 12 hours. If laboratory values are increased, then diagnostic imaging is necessary. For patients with diffuse abdominal pain and for patients with signs of shock or respiratory insufficiency, a CT-scan is the imaging method of choice. If symptoms are located in the left upper quadrant, an upright chest radiograph or a plain abdominal film are recommended. If symptoms are located in the right upper quadrant, ultrasonography will be preferred. If the diagnosis is still uncertain, a CT-scan will be performed. A CT-scan is indicated for lower abdominal pain in women with increased inflammatory parameters and in men aged 50 years or older with increased inflammatory parameters. If the cause of the abdominal pain is still unclear following a CT-scan, then diagnostic laparoscopy may be considered for fertile women of childbearing age and for men aged less than 50 years with signs of appendicitis.     

The influence of reduced oxygen availability on pathogenicity and gene expression in Mycobacterium tuberculosis

We investigated how Mycobacterium tuberculosis responded to a reduced oxygen tension in terms of its pathogenicity and gene expression by growing cells under either aerobic or low-oxygen conditions in chemostat culture. The chemostat enabled us to control and vary the oxygen tension independently of other environmental parameters, so that true cause-and-effect relationships of reduced oxygen availability could be established. Cells grown under low oxygen were more pathogenic for guinea pigs than those grown aerobically. The effect of reduced oxygen on global gene expression was determined using DNA microarray. Spearman rank correlation confirmed that microarray expression profiles were highly reproducible between repeat cultures. Using microarray analysis we have identified genes that respond to a low-oxygen environment without the influence of other parameters such as nutrient depletion. Some of these genes appear to be involved in the biosynthesis of cell wall precursors and their induction may have contributed to increased infectivity in the guinea pig. This study has shown that a combination of chemostat culture and microarray presents a biologically robust and statistically reliable experimental approach for studying the effect of relevant and specific environmental stimuli on mycobacterial virulence and gene expression.     

Falls in community-dwelling stroke survivors: an accumulated impairments model

Falling has been identified as a major complication in persons who have had a stroke. The purpose of this study was to investigate the effect of accumulated impairments on the risk of falling in community-dwelling stroke survivors. METHODS: Community-dwelling stroke survivors were identified from the Kansas City Stroke Study, a large cohort study of stroke survivors. We evaluated the subjects within 14 days of stroke onset. Impairments were determined at baseline and were defined as motor = Fugl-Meyer lower-limb score > 28, sensory = sensory score on National Institutes of Health (NIH) Stroke Scale > 0, and visual = hemianopsia score on NIH Stroke Scale > 0. Accumulated impairments were characterized as motor only (n = 101), motor + sensory (n = 88), and motor + sensory + visual (n = 47). The reference group did not possess motor, sensory, or visual impairments. We completed follow-ups at 1 month, 3 months, and 6 months poststroke to determine the fall status of the subjects. RESULTS: Two hundred eighty subjects were included. Falls were reported by 142 subjects (51%) between 1 month and 6 months poststroke. Univariate analysis revealed that the risk of falling for subjects with motor impairment only was odds ratio (OR) = 2.2 (95% confidence interval [CI] 1.05 to 4.70), motor + sensory impairments OR = 3.1 (95% CI 1.46 to 6.79), and motor + sensory + visual impairments OR = 2.4 (95% CI 1.05 to 5.83) as compared to the group with no motor, sensory, and visual impairments. In multiple logistic regression, the risk of falling increased with motor impairment only and motor + sensory impairments. However, the motor + sensory + visual impairments group had a lower risk of falling. Secondary analysis revealed a significant difference in mobility scores (Orpington Prognostic Scale-balance) among individuals with motor impairment only, motor + sensory impairments, motor + sensory + visual impairments, and the reference group. This lower risk of falling in stroke survivors with motor + sensory + visual impairments may be explained by more involved strokes, more impaired balance, and subsequently less mobility, therefore, lowering their risk of falling. In conclusion, community-dwelling persons who have had a stroke are at a higher risk of falling. However, the risk of falling is not linearly related to the number of impairments. Individuals with motor, sensory, and visual impairments are less mobile and less likely to fall than those individuals with motor deficits only or motor and sensory deficits.