Uncatalyzed assembly of spherical particles from SV40 VP1 pentamers and linear dsDNA incorporates both low and high cooperativity elements

The capsid of SV40 virion is comprised of 72 pentamers of the major capsid protein, VP1. We examined the synergism between pentamer-pentamer interaction and pentamer-DNA interaction using a minimal system of purified VP1 and a linear dsDNA 600-mer, comparing electrophoresis with electron microscopy and size exclusion chromatography. At low VP1/DNA ratios, large tubes were observed that apparently did not survive native agarose gel electrophoresis. As the VP1 concentration increased, electrophoretic migration was slower and tubes were replaced by 200 Å diameter particles and excess free pentamer. At high VP1/DNA ratios, a progressively larger fraction of particles was similar to 450 Å diameter virions. VP1 association with DNA is very strong compared to the concentrations in these experiments yet, paradoxically, stable complexes appear only at high ratios of VP1 to DNA. These data suggest a DNA saturation-dependent nucleation event based on non-specific pentamer-DNA interaction that controls assembly and the ultimate capsid geometry.     

Diffuse ischemia in noncontrast computed tomography predicts outcome in patients in intensive care unit

Purpose

In the intensive care unit (ICU), prognosticating patients who are comatose or defining brain death can be challenging. Currently, the criteria for brain death are clinical supported by paraclinical tests. Noncontrast computed tomography (CT) shows diffuse loss of grey-white differentiation consistent with infarction. We hypothesize that the extent of hypodensity is predictive of poor neurologic outcome or brain death.

Materials and Methods

A total of 235 consecutive adult patients with cardiac arrest or with serious trauma admitted to ICU in 1 year were studied. Seventy met inclusion criteria. CT images were reviewed by multiple observers blinded to final outcome who assessed for loss of grey-white conspicuity. A modification of the validated Alberta Stroke Program Early CT Score (ASPECTS) was used to include non–middle cerebral artery territories. Primary outcome was death or functional disability at 3 months. Dichotomized CT scores were correlated with poor clinical status (Glasgow Coma Score < 5 and APACHE [Acute Physiology and Chronic Health Evaluation] score >19) and poor outcome (modified Rankin Scale >2).

Results

The CT score was ≤10 in 7 patients and >10 in 63 patients. The CT score value correlated with the severity of baseline clinical status on the Glasgow Coma Score (r = 0.53, P < .01) and negatively with the APACHE-II score (r = −0.27, P < .05). The CT score value negatively correlated with functional outcome (r = −0.40, P < .01). All the patients with a CT score ≤10 died. The sensitivity of the CT score for functional outcome was 24%, and specificity was 100%. Agreement among observers for the CT score was good (Intraclass correlation coefficient = 0.77).

Conclusion

Diffuse loss of grey-white matter differentiation is subtle but specific for poor neurologic outcome, which may allow earlier prognostication of patients in whom clinical parameters are difficult to assess.     

Distinct repeat motifs at the C-terminal region of CagA of Helicobacter pylori strains isolated from diseased patients and asymptomatic individuals in West Bengal, India

Background

Infection with Helicobacter pylori strains that express CagA is associated with gastritis, peptic ulcer disease, and gastric adenocarcinoma. The biological function of CagA depends on tyrosine phosphorylation by a cellular kinase. The phosphate acceptor tyrosine moiety is present within the EPIYA motif at the C-terminal region of the protein. This region is highly polymorphic due to variations in the number of EPIYA motifs and the polymorphism found in spacer regions among EPIYA motifs. The aim of this study was to analyze the polymorphism at the C-terminal end of CagA and to evaluate its association with the clinical status of the host in West Bengal, India.

Results

Seventy-seven H. pylori strains isolated from patients with various clinical statuses were used to characterize the C-ternimal polymorphic region of CagA. Our analysis showed that there is no correlation between the previously described CagA types and various disease outcomes in Indian context. Further analyses of different CagA structures revealed that the repeat units in the spacer sequences within the EPIYA motifs are actually more discrete than the previously proposed models of CagA variants.

Conclusion

Our analyses suggest that EPIYA motifs as well as the spacer sequence units are present as distinct insertions and deletions, which possibly have arisen from extensive recombination events. Moreover, we have identified several new CagA types, which could not be typed by the existing systems and therefore, we have proposed a new typing system. We hypothesize that a cagA gene encoding higher number EPIYA motifs may perhaps have arisen from cagA genes that encode lesser EPIYA motifs by acquisition of DNA segments through recombination events.     

Concept of foreign body-its past and present

Endoscopic endonasal dacryocystorhinostomy [EDCR] is considered to be a superior alternative technique to the conventional external dacryocystorhinostomy [DCR], both in primary and secondary cases. It is of particular value in children and young adults as it avoids an external scar. Sixteen cases of chronic dacryo-cystitis were treated by the endoscopic technique, including 8 revision cases of failed external approach. In all cases except one, a patent nasolacrimal fistula was noted, with a success rate of 93.7%. The authors share their experience in EDCR and review the relevant literature.     

Pleomorphic adenoma of the pinna

A rare case of mixed tumour of the pinna is presented and characteristics of its rarity are discussed.     

Force Parameters for On-line Tool Wear Estimation: A Neural Network Approach

Reliable on-line tool conditioning monitoring is an essential feature of modern sophisticated and automated machine tools. Appropriate and timely decision for tool-change is urgently required in the machining systems. Ample researches have been carried out in this direction.

Recently artificial neural networks (NN) are applied for this purpose in conjunction with suitable sensory systems. Its fast processing capability is well-suited for quick estimation of tool condition and corrective measure to be taken.

The present work uses back-propagation type training and feed-forward testing procedures for the neural networks. Three models using different force parameters are tried to monitor tool wear on-line. The close estimation of the modeled output to the actual wear value demonstrates the possibility of successful tool wear monitoring. Copyright © 1996 Elsevier Science Ltd.     

Exploring effects of different nonsteroidal antiinflammatory drugs on malondialdehyde profile

As a part of our ongoing effort to explore drug induced lipid peroxidation in relation to drug-induced toxicity, this study was undertaken to determine whether nonsteroidal anti-inflammatory drugs (NSAIDs), namely, diclofenac sodium, ibuprofen, flurbiprofen, paracetamol, nimesulide, celecoxib and indomethacin are involved in oxidative/antioxidative processes by determining malondialdehyde (MDA) concentration as an index of lipid peroxidation. Considering lipid peroxidation, a possible mediator of toxicity, an attempt was made to see the suppressive action of ascorbic acid, a conventional antioxidant compound, on NSAID-induced lipid peroxidation. It was found that diclofenac sodium, ibuprofen, flurbiprofen and paracetamol exerted statistically significant decrease of MDA content, suggesting a potential of the molecules to suppress the lipid peroxidation. At earlier stage of incubation nimesulide shows statistically significant decrease of MDA content followed by lipid peroxidation induction at the later stage of incubation period, suggesting involvement of nimesulide in antioxidative/oxidative processes. Celecoxib and indomethacin both exerted statistically significant increase of MDA content, representing significant peroxidation activity. Ascorbic acid, a promising antioxidant, could significantly reduce celecoxib and indomethacin induced lipid peroxidation.