Repair of extensive ionizing-radiation DNA damage at 95 degrees C in the hyperthermophilic archaeon Pyrococcus furiosus

We investigated the capacity of the hyperthermophile Pyrococcus furiosus for DNA repair by measuring survival at high levels of 60Co gamma-irradiation. The P. furiosus 2-Mb chromosome was fragmented into pieces ranging from 500 kb to shorter than 30 kb at a dose of 2,500 Gy and was fully restored upon incubation at 95 degrees C. We suggest that recombination repair could be an extremely active repair mechanism in P. furiosus and that it might be an important determinant of survival of hyperthermophiles at high temperatures.     

Effect of preoperative supplementation with alpha-tocopherol and ascorbic acid on myocardial injury in patients undergoing cardiac operations

Augmentation of antioxidant defenses may help protect tissues against ischemia-reperfusion injury associated with operations involving cardiopulmonary bypass. In this study we examined the effect of pretreating patients with alpha-tocopherol (vitamin E) and ascorbic acid (vitamin C) or placebo on injury to the myocardium. Seventy-six subjects undergoing elective coronary artery bypass grafting participated in a prospective, double-blind, placebo-controlled randomized trial, receiving either placebo or both 750 IU dl-alpha-tocopherol per day for 7 to 10 days and 1 gm ascorbic acid 12 hours before the operation. Plasma alpha-tocopherol concentrations, raised fourfold by supplementation, fell by 70% after the operation in the supplemented group and to negligible levels in the placebo group. There were no significant differences between the groups with respect to release of creatine kinase MB isoenzyme over 72 hours, nor in the reduction of the myocardial perfusion defect determined by thallium 201 uptake. Electrocardiography provided no evidence of a benefit from antioxidant supplementation. Thus the supplementation regimen prevented the depletion of the primary lipid soluble antioxidant in plasma, but provided no measurable reduction in myocardial injury after the operation.     

Kinetic evidence for low chemical processivity in ncd and Eg5

We have examined the formation of hydroxyphenols, nitrophenols, and the minor products 4-nitrosophenol, benzoquinone, 2,2'-biphenol, and 4,4'-biphenol from the reaction of peroxynitrite with phenol in the presence and absence of added carbonate. In the absence of added carbonate, the product yields of nitrophenols and hydroxyphenols have different pH profiles. The rates of nitration and hydroxylation also have different pH profiles and match the trends observed for the product yields. At a given pH, the sum of the rate constants for nitration and hydroxylation is nearly identical to the rate constant for the spontaneous decomposition of peroxynitrite. The reaction of peroxynitrite with phenol is zero-order in phenol, both in the presence and absence of added carbonate. In the presence of added carbonate, hydroxylation is inhibited, whereas the rate of formation and yield of nitrophenols increase. The combined maximum yield of o- and p-nitrophenols is 20 mol% (based on the initial concentration of peroxynitrite) and is about fourfold higher than the maximal yield obtained in the absence of added carbonate. The o/p ratio of nitrophenols is the same in the presence and absence of added carbonate. These results demonstrate that hydroxylation and nitration occur via two different intermediates. We suggest that the activated intermediate formed in the isomerization of peroxynitrous acid to nitrate, ONOOH*, is the hydroxylating species. We propose that intermediate 1, O=N-OO-CO2-, or secondary products derived from it, is (are) responsible for the nitration of phenol. The possible mechanisms responsible for nitration are discussed.     

A role for B cells in the development of T cell helper function in a malaria infection in mice

B cell knockout mice are unable to clear a primary erythrocytic infection of Plasmodium chabaudi chabaudi. However, the early acute infection is controlled to some extent, giving rise to a chronic relapsing parasitemia that can be reduced either by drug treatment or by adoptive transfer of B cells. Similar to mice rendered B-cell deficient by lifelong treatment with anti-mu antibodies, B cell knockout mice (muMT) retain a predominant CD4+ Th1-like response to malarial antigens throughout a primary infection. This contrasts with the response seen in control C57BL/6 mice in which the CD4+ T-cell response has switched to that characteristic of Th2 cells at the later stages of infection, manifesting efficient help for specific antibodies in vitro and interleukin 4 production. Both chloroquine and adoptive transfer of immune B cells reduced parasite load. However, the adoptive transfer of B cells resulted in a Th2 response in recipient muMT mice, as indicated by a relative increase in the precursor frequency of helper cells for antibody production. These data support the idea that B cells play a role in the regulation of CD4+ T subset responses.     

International developments in solar thermal testing

A methodology of the design of solar energy test facilities is presented. In the design of the test facilities, careful attention has been paid to the availability of local materials and skilled labour to perform tests on solar energy equipment to international standards. Outdoor test results are presented for collector tests performed to ASHRAE standards on site in Egypt. The results are compared with indoor tests from the UK National Test Laboratory using the SERC solar simulator at University of Wales College of Cardiff, UK. Data analysis has been carried out on the outdoor and indoor results to determine the performance of these collectors. The indoor and outdoor results agreed very well. The indoor results have been corrected in accordance with International Standards to yield an ‘equivalent outdoor’ peformance characteristic. The emerging international standards for solar thermal testing are discussed, particularly in a developing country context.     

Correlation study on infrared thermography and nerve root signs in lumbar intervertebral disk herniation patient: a short report

OBJECTIVE: To determine whether infrared skin thermography is an objective measurement reflecting the seriousness of nerve root irritation in lumbar disk herniation patients. DESIGN: Quantified nerve root signs by physical examination were collected from the patients along with the infrared skin temperature measurement on the lumbosacral region and posterior part of thighs. A correlation study was applied to observe the relation between the nerve root signs and the skin temperature before a successful conservative treatment (mainly spine manipulation), and between the alteration of nerve root signs and that of skin temperature after the treatment. SETTING: Hospitalized care. PATIENTS: Twenty-seven hospitalized samples with computed tomography or magnetic resonance approval were consecutively selected during the latter half of 1990. MAIN OUTCOME MEASURE: Changes in nerve root signs. RESULTS: The temperature difference between a troubled thigh and healthy one is significantly correlated to the score of the nerve root signs before the treatment; and the reduction of temperature difference between two thighs is also significantly correlated with decreasing score of nerve root signs after the treatment. The correlation between the temperature difference on the left and right sides of the lumbosacral region and the nerve root signs before the treatment is insignificant; and the variation of the temperature difference of the same region after the treatment is not correlated with the decreasing score of the nerve root signs. CONCLUSION: Infrared skin thermography of lower extremities might be an objective sign in signaling the soothing process of the nerve root irritation in lumbar disk herniation patients, which may help a doctor in checking the responses of the patient to treatment.     

Characterization of protease-catalyzed hydrolysis of cyanine-labeled angiotensin using capillary electrophoresis with laser-induced fluorescence detection

The hydrolytic cleavage of a cyanine (Cy3)-labeled angiotensin, catalyzed by various proteases, was studied by capillary electrophoresis (CE) with laser-induced fluorescence detection (LIF). The end-labeled peptides and the Cy3 diacid internal standard were separated on a 20-microns x 27-cm capillary with LIF detection (emission, 580 nm) using a frequency-doubled solid-state diode laser emitting at 532 nm or a He-Ne laser emitting at 543 nm. Hydrolysis of the Cy3-labeled angiotensin I, catalyzed by proteinase K, is a sequential process beginning from the C-terminal of the peptide, instead of from random cleavages. Trypsin catalyzes a specific cleavage of Cy3-angiotensin I to Cy3-Asp-Arg as anticipated. Using a combination of endopeptidase and carboxypeptidases, the remnant of the labeled species was characterized by CE-LIF. The method provides a general tool for studying the mechanism of protease-catalyzed hydrolysis of peptide.