Variability in the stability of DNA-peptide nucleic acid (PNA) single-base mismatched duplexes: real-time hybridization during affinity electrophoresis in PNA-containing gels

The stability of all single-base mismatched pairs between a peptide nucleic acid 11-mer and its complementary DNA has been quantified in terms of their melting temperature and compared with the limited amount of data published to date. The strength of the interaction was determined by an automated affinity-electrophoretic approach permitting the visualization, in real time, of hybridization between a physically immobilized peptide nucleic acid and a complementary DNA migrating in an electric field. The dissociation constants are in the range of 10(-7) M (for mismatches) to 10(-10) M (for fully complementary DNA), which are in excellent agreement with solution studies. These and other thermodynamic constants can be accurately, rapidly, and reproducibly measured in this system at concentrations approaching dissociation conditions by using fluorescently labeled DNA in conjunction with commercial DNA sequencers. The stability of single-base mismatched peptide nucleic acid-DNA duplexes depends both on the position as well as on the chemical nature of the mismatch. The stability is at a minimum when the mutation is positioned 4 bases from either terminus (a loss of 20 degreesC or more in the melting temperature) but regains substantial stability when the mismatch is at the center of the duplex. The most stable mismatched pairs are G:T and T:T whereas destabilization is maximal for A:A and G:G. These observations are of significance in the design of probes for detecting mutations by hybridization.     

The amyloid beta protein induces oxidative damage of mitochondrial DNA

A 55-year-old man was admitted to our hospital with of hemoptysis, progression of anemia and renal failure in February, 1996. Idiopathic interstitial pneumonia had been diagnosed and he had been followed at a regional hospital since 1988. On the third day after admission, he suffered from sudden and massive hemoptysis. Goodpasture's syndrome was diagnosed because anti-GBM antibody was detected in serum. A high titer of MPO-ANCA was also recognized simultaneously. Steroid pulse therapy, immunosuppressive therapy, and plasmapheresis were begun, but he died on the 28th hospital day because of severe hypoxemia and multi-organ failure. Histological examination after autopsy revealed crescentic glomerulonephritis with linear deposition of IgG in the glomerular capillary wall, and interstitial pneumonia accompanied by massive alveolar hemorrhage. It was suggested that in this patient, not only anti-GBM antibody but also circulating MPO-ANCA might have participated in the progression of the crescentic glomerulonephritis and alveolar hemorrhage observed in Goodpasture's syndrome.     

Does the association of risk factors and atherosclerosis change with age? An analysis of the combined ARIC and CHS cohorts. The Atherosclerosis Risk in Communities (ARIC) and Cardiovascular Health Study (CHS) investigators

INTRODUCTION: A decrease in the estimated relative risk of cerebrovascular and cardiovascular diseases associated with known disease risk factors has been observed among elderly cohorts, perhaps suggesting that continued risk factor management in the elderly may not be as efficacious as with younger age groups. In this paper, the differential magnitude of the association of risk factors with atherosclerosis across the age spectrum from 45 years to older than 75 years is presented. METHODS: Subclinical atherosclerosis as measured by carotid ultrasonography and risk factor prevalence were assessed using similar methods among participants aged 45 to 64 years in the Atherosclerosis Risk in Communities (ARIC) study and among participants 65 years and older in the Cardiovascular Health Study (CHS). Pooling these two cohorts provided data on the relationship of risk factors and atherosclerosis on nearly 19,000 participants over a broad age range. Regression analyses were used to assess the consistency of the magnitude of the association of risk factors with atherosclerosis across the age spectrum separately for black and white participants in cross-sectional analyses. RESULTS: As expected, each of the risk factors was globally (across all ages) associated with increased atherosclerosis. However, the magnitude of the association did not differ across the age spectrum for hypertension, low density lipoprotein cholesterol (LDL-c), fibrinogen, or body mass index (BMI). For whites, there was a significantly greater impact of smoking and HDL-C among older age strata but a smaller impact of diabetes. For black women, the impact of HDL-C decreased among the older age strata. CONCLUSIONS: These data suggest that most risk factors continue to be associated with increased atherosclerosis at older ages, possibly suggesting a continued value in investigation of strategies to reduce atherosclerosis by controlling risk factors at older ages.     

Reduced systemic arterial compliance is associated with left ventricular hypertrophy and diastolic dysfunction in older people

OBJECTIVES: To study the relationship between left ventricular diastolic function and systemic arterial compliance in the older population. DESIGN: Cross-sectional survey. PARTICIPANTS: A total of 67 older volunteer participants (aged 67 +/- 5.4 years). MEASUREMENTS: Systemic arterial compliance (SAC) was measured using applanation tonometry and aortic velocimetry, and diastolic function was assessed using Doppler filling. Left ventricular mass was determined echocardiographically. RESULTS: There were significant univariate correlations between diastolic filling, as measured by E/A ratio, systemic arterial compliance (0.34, P < .01), and left ventricular mass (-0.41, P < .001). In multiple regression analysis, using diastolic filling as the dependent variable and heart rate, age, left ventricular mass corrected for body surface area, systolic and diastolic blood pressures, and arterial compliance as independent variables, the major determinants of diastolic filling were heart rate, left ventricular mass, and diastolic blood pressure. Arterial compliance did not make a significant independent contribution. CONCLUSION: This study demonstrates a positive relationship between diastolic filling and arterial compliance in the older population. However, in multiple regression analysis, heart rate, diastolic blood pressure, and left ventricular mass were the independent predictors of diastolic filling (E/A), whereas arterial compliance was not. These findings imply that therapeutic modulation of aortic stiffness would not, of itself, contribute to improvement in diastolic function.     

Early administration of ramipril in acute myocardial infarction: neurohormonal and hemodynamic effects and tolerability

Although several large studies indicate a beneficial effect of angiotensin-converting enzyme (ACE) inhibitors after myocardial infarction, the optimal timing of therapy in terms of safety and the effects on neurohormones during myocardial infarction are less well known. In order to investigate the effect of ramipril, administered within 24 h after myocardial infarction, on hemodynamics and neurohormones and its safety, 20 patients with a myocardial infarction were studied. Nine patients had an anterior, 10 an inferior, and 1 a non-Q-wave infarction. Fourteen patients received thrombolytic therapy, whereas 6 did not. The initial dose of ramipril was 1.25 mg, but was gradually increased to 5 mg during the next 4 days. Side effects did not occur. The mean arterial pressure decreased 8 h after the first dose from 84 +/- 2 mm Hg (control) to 77 +/- 2 mm Hg (p < 0.05) and remained decreased thereafter. This was accompanied by a reduction in systemic resistance of 8% after 8 h and of 12% on day 2. Heart rate, cardiac and stroke indexes, and pulmonary artery and wedge pressures did not change. The ACE activity decreased within 1 h of ramipril administration with a maximum of 71% at 4 h after the second dose and remained at this level throughout the study. Angiotensin II decreased by 34% (day 2) and by 41% (day 5). The renin activity gradually increased from 33 +/- 7.5 to 75.4 +/- 11.5 microM/ml on day 5, whereas epinephrine was reduced from day 2 onwards, with a maximal reduction of 71% on day 5. Arginine vasopressin was significantly reduced 5 h after ramipril administration until the end of the study, with a maximum of 77% on day 3. Moreover, a late but significant decrease in norepinephrine occurred on day 5. Thus, oral ramipril results in early ACE inhibition, followed by progressive attenuation of the neuroendocrine activation and a reduction in afterload during the acute phase of myocardial infarction. It is well tolerated, also in combination with nitroglycerin and thrombolytic therapy.     

PCR-ribotyping and pyrolysis mass spectrometry fingerprinting of environmental and hospital isolates of Clostridium difficile

Pancreatic ischemia is a very rare etiology of clinical acute pancreatitis, complicating cardiac surgery, hemorrhagic shock, and transplantation of the pancreas. In this article, we present two patients with acute ischemic necrotizing pancreatitis, complicating a generalized atheromatous disease with extensive lesions in the splanchnic circulation (patient 1) and repair of a descending thoracic aortic aneurysm (patient 2). Diagnostic approach and management of ischemic necrotizing pancreatitis are discussed.     

Neuron discharges in the rat auditory cortex during electrical intracortical stimulation

Cocaine and cocaine-associated cues elicit craving in addicts and reinstate cocaine-seeking behavior in rats. Craving and cocaine-seeking behavior may be mediated by withdrawal-induced changes in dopamine (DA) neurotransmission in the amygdala. To examine whether there are concomittant changes in cocaine-seeking behavior and extracellular DA levels during withdrawal, experimental rats were trained to self-administer cocaine (0.75 mg/kg i.v.). After 14 daily 3-hour training sessions, animals underwent either a 1-day, 1-week, or 1-month withdrawal period. Extracellular DA levels were assessed during baseline, extinction, cue reinstatement, and cocaine (15 mg/kg i.p.) reinstatement of cocaine-seeking behavior (i.e., defined as the difference in nonreinforced lever presses on an active minus inactive lever). Cocaine-seeking behavior became more intense during the course of cocaine withdrawal. Additionally, basal and cocaine-induced extracellular DA levels were enhanced after the 1-month withdrawal period. We suggest that the former may reflect a persistent elevation in tonic extracellular DA levels in the amygdala, whereas the latter may reflect a persistent elevation in phasic extracellular DA levels.     

Biodegradation and biocompatibility of a guided tissue regeneration barrier membrane formed from a liquid polymer material

Biodegradable barrier films were made by coagulating a solution of poly(DL-lactide) in N-methyl-2-pyrrolidone on porous polyethylene pads wetted with saline solution. The semisolid films were cut into 10 x 10 mm barriers and implanted subcutaneously in rabbits. At monthly intervals, the polymer implant sites were compared histologically to those implanted with USP negative control plastic. The polymer films were retrieved from the surrounding tissue, dried, weighed, and the changes in molecular weight determined using gel permeation chromatography. The molecular weight of the polymer decreased at a relatively constant rate over 5 months; however, no significant mass loss occurred until 5 months postimplantation. Also, no distinct histological differences were noted between the polymer barrier and the control plastic sites until 6 months when histiocytes and multinucleated giant cells showed a modest increase around fragmented polymer films. Similar barrier films also were fitted over naturally occurring buccal dehiscence defects in beagle dogs and the tissue sites compared histologically at 6 months to sham-operated control sites. New bone and dense connective tissues closely approximated segments of the remaining polymer and demonstrated the biocompatibility of the biodegradable films. Histomorphometric analyses of treated sites compared to sham controls showed that the polymer barrier is effective in promoting bone and cementum regeneration in periodontal defects in dogs.     

Completion rates and feasibility of outcome measures: experience in a multicenter clinical trial of systemic hypothermia for severe head injury

The National Acute Brain Injury Study: Hypothermia (NABIS:H) is an ongoing multicenter trial of systemic hypothermia for the treatment of severe head injury. Follow-up rates for the study's 3-and 6-month outcome assessments have been maintained at high levels by establishing close contact with family members, by reimbursing cost of travel, and by sending examiners to the subject's location whenever necessary. Two years into the study, global disability data (e.g., Glasgow Outcome Scale) have been obtained on 86% of patients due for 3-month assessment (n = 131) and for all subjects due at 6 months (n = 100). Over half of the patients have completed neuropsychological testing with high reliability ratings. These preliminary findings suggest that the procedures used to document data quality and increase follow-up and completion rates are being successful.