Structural and functional conservation of the human homolog of the Schizosaccharomyces pombe rad2 gene, which is required for chromosome segregation and recovery from DNA damage

The rad2 mutant of Schizosaccharomyces pombe is sensitive to UV irradiation and deficient in the repair of UV damage. In addition, it has a very high degree of chromosome loss and/or nondisjunction. We have cloned the rad2 gene and have shown it to be a member of the Saccharomyces cerevisiae RAD2/S. pombe rad13/human XPG family. Using degenerate PCR, we have cloned the human homolog of the rad2 gene. Human cDNA has 55% amino acid sequence identity to the rad2 gene and is able to complement the UV sensitivity of the rad2 null mutant. We have thus isolated a novel human gene which is likely to be involved both in controlling the fidelity of chromosome segregation and in the repair of UV-induced DNA damage. Its involvement in two fundamental processes for maintaining chromosomal integrity suggests that it is likely to be an important component of cancer avoidance mechanisms

Effects of weightlessness on tissue proliferation

The repair of bone marrow stroma following mechanical injury was studied to obtain baseline data for a proposed space experiment regarding the effect of weightlessness on marrow stroma and other proliferating cell systems

Heterogeneous nucleation near a metastable vapour-liquid transition: the effect of wetting transitions

Phase transformations such as freezing typically start with heterogeneous nucleation. Heterogeneous nucleation near a wetting transition, of a crystalline phase is studied. The wetting transition occurs at or near a vapour-liquid transition which occurs in a metastable fluid. The fluid is metastable with respect to crystallisation, and it is the crystallisation of this fluid phase that we are interested in. At a wetting transition a thick layer of a liquid phase forms at a surface in contact with the vapour phase. The crystalline nucleus is then immersed in this liquid layer, which reduces the free energy barrier to nucleation and so dramatically increases the nucleation rate. The variation in the rate of heterogeneous nucleation close to wetting transitions is calculated for systems in which the longest-range forces are dispersion forces.Comment: 11 pages including 3 figure

Application of Rational Second Kind Chebyshev Functions for System of Integrodifferential Equations on Semi-Infinite Intervals

Rational Chebyshev bases and Galerkin method are used to obtain the approximate solution of a system of high-order integro-differential equations on the interval [0,∞). This method is based on replacement of the unknown functions by their truncated series of rational Chebyshev expansion. Test examples are considered to show the high accuracy, simplicity, and efficiency of this method

Undulation Instability of Epithelial Tissues

Treating the epithelium as an incompressible fluid adjacent to a viscoelastic stroma, we find a novel hydrodynamic instability that leads to the formation of protrusions of the epithelium into the stroma. This instability is a candidate for epithelial fingering observed in vivo. It occurs for sufficiently large viscosity, cell-division rate and thickness of the dividing region in the epithelium. Our work provides physical insight into a potential mechanism by which interfaces between epithelia and stromas undulate, and potentially by which tissue dysplasia leads to cancerous invasion.Comment: 4 pages, 3 figure

Effect of irrigation frequency and application levels of sulphur fertilizer on water use efficiency and yield of Indian mustard (Brassica juncea)

A field experiment was conducted at Indian Agricultural Research Institute, New Delhi during the crop season of 2007 to 2008 and 2008 to 2009 to study the effect of irrigation and sulphur on yield and water use efficiency of Indian mustard (Brassica juncea var. PusaJagannath). The experiment was carried out in split plot design with three replications. The treatments consisted of three levels of irrigation in the main plots [no irrigation, one irrigation at 45 days after sowing (DAS), and two irrigations at 45 DAS and 90 DAS] and four levels of sulphur in sub-plots (0, 15, 30, and 45 kg S/ha). The results showed that in both years of experimentation, application of two irrigations significantly increased the India mustard yield as indicated by dry matter accumulation, seed production, biological/biomass yield, and harvest index, in comparison to no irrigation. Also, the application of two irrigations, been on par with one irrigation, significantly enhanced seed and biological yield to 20.6 and 78.0 q/ha respectively in the first year, and 22.9 and 86.7 q/ha respectively in the second year, and the highest harvest index was obtained from the application of two irrigations in both years of the study. Water use efficiency as indicated by seasonal consumptive water use increased progressively with the increasing number of irrigations. Also, the amount of soil moisture extraction by the crop from upper layers increased and those from lower depth decreased with increase in the level of irrigation (from no irrigation to two irrigations) in both years of the study. Application of two irrigations to mustard gave higher net (yield) return and benefit-cost (B: C ratio) over one irrigation, which in turn, gave higher net benefit-cost return and B: C ratio than no irrigation. The increasing levels of sulphur application increased Indian mustard dry matter accumulation, seed and biological yield and harvest index. Seasonal consumptive water use by the crop and water use efficiency increased progressively with the increase level of sulphur application up to 45 kg S/ha . Quantity of soil moisture extraction from deeper layer increased with increase in the levels of sulphur application.Key words: Indian mustard, Irrigation, Sulphur, Water use efficiency, Economic evaluation

Reviewing traffic conflict techniques for potential application to developing countries

The economic and social costs due to road crashes are disproportionately higher in developing countries. In addition, underreporting, coupled with an incomplete and inconsistent recording of reported crashes is a major issue in such settings. A brief outline of the dimension of road safety problems in developing countries and the most common limitations of existing crash databases is given in the paper. The challenges in applying traditional approaches for traffic safety evaluation and initiatives are also discussed. Diagnosis of road safety problems using traffic conflict techniques has received considerable research interest and has gained acceptance as a proactive surrogate measure in developed countries. Significant studies have been accomplished to develop, validate and apply different surrogate indicators for the estimation of traffic conflicts, as well as an assessment of the safety problem in different road geometric and operating conditions. This has provided a substitute for the historical crash records in traffic safety research. The main objective of this paper is to assess the application potentiality of this surrogate safety measures to address safety issues in developing countries. To do that, this paper critically reviews and synthesizes the different indicators of surrogate safety measures. The main principles, as well as advantages and disadvantages of the major indicators and prospects of application, are presented here. Finally, future research directions for road traffic safety assessment are outlined in the perspective of understanding the most concerning human issue due to traffic crashes in developing countries

Clinical survey of cerebrovascular disease in children

Objective: Stroke is defined as the sudden occlusion or rupture of cerebral arteries or veins resulting in focal cerebral damage and clinical neurologic deficits. The risk factors for stroke in children are numerous and differ from those in adults. Identification of these factors can prevent subsequent strokes. The aim of this study is to determine the etiology of stroke in children. Methods: In this descriptive prospective study, children who were referred to pediatric neurology clinic in Mofid Children's Hospital due to acute hemiparesis during 2 years period (Sep 2003-Sep 2005) were evaluated and their diagnosis was cerebrovascular disorders, in the view of physical examination and brain imaging. Findings: The study group consisted of 40 children in age groups between 3 months to 14 years old. The most common age group at presentation was 2 to 5 years old. Occurrence was predominant during autumn and winter (70). The most common clinical presentations were acute hemiparesis (85) and seizures (40). The other symptoms were as follow: 15 decreased level of consciousness, 12.5 fever, 7.5 VI nerve palsy, and 2.5 cerebellar signs. 20 of patients suffered from hemorrhagic and 80 had ischemic stroke. In 60 of the patients specific etiologic factors were identified and in the rest of the group, risk factors could be delineated. The most common etiologies were: 17.5 cardiac diseases or procedures and 10 hematologic disorders. Other etiologies included: 7.5 prothrombotic states, 7.5 CNS infection, 5 mitochondriopathy, 2.5 for each of the head trauma, migraine, serum lipid abnormality, hypertension and arteriovenus malformation. The most common risk factors consisted of 40 anemia and 20 infections. Conclusion: This study demonstrates that stroke in children is a multifactorial process. Identification of the underlying risk factors for cerebrovascular disorders is highly desirable because many of the risk factors can be prevented, resulting in reduction of the risk of subsequent strokes