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Biomedical subjects

S Kumar

Publications and source records attributed to S Kumar.

At least 793 records · Page 44Linked to original sources
PubMed1999

Expression, purification and characterization of peanut (Arachis hypogaea) agglutinin (PNA) from baculovirus infected insect cells.

Peanut (Arachis hypogaea) seed lectin, PNA is widely used to identify tumor specific antigen (T-antigen), Galbeta1-3GalNAc on the eukaryotic cell surface. The functional amino acid coding region of a cDNA clone, pBSH-PN was PCR amplified and cloned downstream of the polyhedrin promoter in the Autographa californica nucleopolyhedrovirus (AcNPV) based transfer vector pVL1393. Co-transfection of Spodoptera frugiperda cells (Sf9) with the transfer vector, pAcPNA and AcRP6 (a recombinant AcNPV having B-gal downstream of the polyhedrin promoter) DNAs produced a recombinant virus, AcPNA which expresses PNA. Infection of suspension culture of Sf9 cells with plaque purified AcPNA produced as much as 9.8 mg PNA per liter (2.0 x 10(6) cells/ml) of serum-free medium. Intracellularly expressed protein (re-PNA) was purified to apparent homogeneity by affinity chromatography using ECD-Sepharose. Polyclonal antibodies against natural PNA (n-PNA) cross-reacted with re-PNA. The subunit molecular weight (30 kDa), hemagglutination activity, and carbohydrate specificity of re-PNA were found to be identical to that of n-PNA, thus confirming the abundant production of a functionally active protein in the baculovirus expression system.

Animals↗
PubMed1999

Pregnancy and its outcome in patients with noncirrhotic portal hypertension.

There is paucity of data in the literature on the occurrence of pregnancy and its outcome in patients with noncirrhotic portal hypertension. The present study was undertaken to assess the fertility pattern, fetal loss, and consequences of variceal bleeding during pregnancy in these patients. Fifty-five women of child-bearing age with a diagnosis of noncirrhotic portal hypertension (including 32 with noncirrhotic portal fibrosis and 23 with extrahepatic portal venous obstruction) and 44 age-matched controls were studied. A detailed history of obstetric events and bleeding episodes was recorded in all patients. Any complication of portal hypertension was managed accordingly. Patients were classified into three groups for analysis: group 1-obstetric events after the diagnosis of portal hypertension in patients; group II-obstetric events before the diagnosis of portal hypertension in patients; and group III-obstetric events in controls. A total of 116 pregnancies took place in 44 patients. Of these, 36 occurred after and 80 before the diagnosis of portal hypertension was made. In the 44 controls, 118 pregnancies took place. The mean fertility rates of groups I, II and III were 0.20+/-0.24, 0.18+/-0.21, and 0.22+/-0.12 pregnancies per year, respectively, which were not statistically different (P>0.05). The numbers of fetal losses in groups I, II and III were 3/36 (8.3%), 6/80 (7.5%), and 12/118 (10.17%) pregnancies, respectively. Menstrual irregularities were found in 7/55 (12.72%) patients and 6/44 (13.6%) controls (P>0.05). Five episodes of variceal bleeding occurred in 36 pregnancies after the diagnosis of portal hypertension (13.88%). All five were successfully managed with endoscopic sclerotherapy. In conclusion, noncirrhotic portal hypertensive patients have normal fertility and outcome of pregnancy. Variceal bleeding episodes are not common and endoscopic sclerotherapy is safe and effective in pregnancy.

Adult↗
PubMed1999

Mechanisms mediating caspase activation in cell death.

The initial activation of a caspase in a caspase cascade is a crucial event that determines whether a cell will ultimately undergo cell death. Although each cell contains a number of different caspases, only a small subset may be required for apoptosis in response to a specific stimulus. It now seems that each caspase cascade has two types of caspases involved, the upstream or class I caspases, and the downstream or class II caspases. Class I caspases are characterised by long amino-terminal prodomains that carry specific protein - protein interaction domains which mediate oligomerisation of caspases, often assisted by specific adaptor molecules. Oligomerisation appears to be sufficient for autocatalytic activation of class I caspases. Once the first caspase in the pathway has been activated, it processes downstream caspases initiating a cascade of amplifying events that lead to the apoptotic death of a cell. This article reviews our current understanding of mechanisms that mediate the activation of caspases.

Animals↗
PubMed1999

Tuberculosis of spine (C1 to D4).

CLINICAL DATA: Thirty-one patients with 33 lesions of spinal tuberculosis (C1-D4) are reported. The distribution of lesions was C1-C2 (11), C3-C6 (13), C7-D4 (9). Neurological complications were present in 6 (55%), 8 (61%) and 7 (78%) in each region respectively. DIAGNOSIS: Increase in the prevertebral soft tissue shadow in a standard radiograph was a useful guide to resort to CT Scan/MRI to diagnose tuberculosis of C1 and C2 region at an early (pre-subluxation) stage. The diagnosis of TB spine from C3-C6 was made confidently on clinico-radiological features. The anterior convexity and forward displacement of tracheal shadow of more than 8 mm from the vertebral bodies in a lateral view of plain X-ray and widening of superior mediastinum in an AP X-ray are useful indicators of tuberculous involvement at cervicodorsal region (C7-D4). CT Scan/MRI should be done for early diagnosis in those cases with a high index of suspicion. TREATMENT AND OUTCOME: 12/33 lesions without neural complications healed with antitubercular drugs and the use of suitable orthosis. Out of 21 lesions with neural complications 14 recovered by local rest, skull traction and multidrug therapy. Seven lesions were surgically decompressed. Of these, five recovered completely, two did not achieve useful recovery. The neural recovery following the middle path regimen for tuberculosis of C1-D4 was 90% in our cases.

Adolescent↗
PubMed1999

Detection of chlorophenolics in effluents from bleaching processes of rice-straw pulp.

A number of chlorinated derivatives of phenols, catechols, guaiacols, syringaldehydes, have been detected and their concentrations estimated, using gas chromatography in the chlorination (C) and extraction (E) stage of spent bleach liquor generated in the laboratory by bleaching rice-straw soda pulp. The concentration of various compounds detected have also been compared with their reported 96LC50 values.

Animals↗
PubMed1999

Carbon catabolite repression of the Aspergillus nidulans xlnA gene.

Expression of the Aspergillus nidulans 22 kDa endoxylanase gene, xlnA, is controlled by at least three mechanisms: specific induction by xylan or xylose; carbon catabolite repression (CCR); and regulation by ambient pH. Deletion analysis of xlnA upstream sequences has identified two positively acting regions: one that mediates specific induction by xylose; and another that mediates the influence of ambient pH and contains two PacC consensus binding sites. The extreme derepressed mutation creAd30 results in considerable, although not total, loss of xlnA glucose repressibility, indicating a major role for CreA in its CCR. Three consensus CreA binding sites are present upstream of the structural gene. Point mutational analysis using reporter constructs has identified a single site, xlnA.C1, that is responsible for direct CreA repression in vivo. Using the creAd30 derepressed mutant background, our results indicate the existence of indirect repression by CreA.

Aspergillus nidulans↗
PubMed1999

Lack of immunological cross-reactivity of 36-kDa secretory salivary gland antigen of Hyalomma anatolicum anatolicum with Hyalomma dromedarii and Boophilus microplus ticks.

During feeding of ticks of the species Hyalomma anatolicum anatolicum, most of the proteins in salivary gland extracts (SGEs) remained unchanged from the unfed to the fully fed state (from day 1 to day 7 of the experiment), as revealed by SDS-PAGE. However, a 45-kDa protein band disappeared and 26-, 32- and 33-kDa bands appeared when feeding commenced. Some of the protein bands changed their intensity. When probed with anti-H. anatolicum anatolicum hyperimmune sera, transblotted SGE proteins of unfed H. anatolicum anatolicum and Hyalomma dromedarii revealed two common bands of 105 and 80 kDa. A 36-kDa protein band present in H. anatolicum anatolicum SGE could not be detected in H. dromedarii. None of these proteins were detected in partly fed Boophilus microplus when probed with anti-H. anatolicum anatolicum hyperimmune serum. This H. anatolicum anatolicum specific 36-kDa protein was strongly recognized throughout feeding, and thus may be an immunogen of importance for the development of an H. anatolicum anatolicum specific serodiagnostic assay.

Animals↗
PubMed1999

Regulation of caspase activation in apoptosis: implications in pathogenesis and treatment of disease.

1. Apoptosis is an essential process to remove excess, unwanted and harmful cells and maintain homeostasis. One of the key steps in apoptosis is activation of a group of proteases termed caspases. 2. Caspases are cysteine proteases that cleave their substrates after an aspartate residue. Approximately one dozen such proteases have been cloned during the past few years. While some caspases are largely responsible for the proteolytic processing of proinflammatory cytokines, such as interleukin (IL)-1 beta, others are directly involved in the execution of apoptosis. 3. Once apoptotic upstream caspases are activated in response to specific apoptotic stimuli, they can activate the downstream or effector class of caspases. Most proteins that are cleaved during apoptosis leading to the characteristic apoptotic morphology are targeted by the downstream caspases. The cleavage of these proteins by caspases can be either an activating or inactivating event for the function of a protein; however, in most cases, it contributes to the apoptotic phenotype of the cell. 4. Because caspase cleavage is the initiating event in most forms of apoptosis, it is a tightly controlled process with many checks and balances. An understanding of the regulation of caspases is providing novel ways for therapeutic intervention to modulate apoptotic behaviour of cells in many diseases that arise due to inappropriate apoptosis. 5. The present article will endeavour to discuss recent advances in our understanding of caspase regulation and will elaborate on how this knowledge is being used in the development of new classes of therapeutic molecules that can be used for the treatment of human ailments.

Animals↗
PubMed1999

Targeted disruption of caspase genes in mice: what they tell us about the functions of individual caspases in apoptosis.

Cysteine proteases of the caspase family are crucial mediators of apoptosis. All mammalian cells contain a large number of caspases. Although many caspases are activated in a cell committed to apoptosis, recent data from caspase gene knockout mice suggest that individual caspases may be involved in the cell and stimulus-specific pathways of cell death. The gene disruption studies also establish the functional hierarchy between two structurally distinct classes of caspases. The present review discusses these recent findings and elaborates on how these mutant mouse models have helped the understanding of the mechanisms that govern programmed cell death in the immune and other systems.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Duplex Doppler sonography in patients with Budd-Chiari syndrome.

BACKGROUND: Angiography has been the mainstay for diagnosis of Budd-Chiari syndrome even though other modalities are increasingly being used. We have evaluated our findings of duplex Doppler sonography (DDS) in patients with Budd-Chiari syndrome. METHODS: Duplex Doppler sonography was performed in 37 consecutive angiographically proven patients with Budd-Chiari syndrome. RESULTS: Real time ultrasonography showed abnormalities of right, middle and left hepatic veins (HV) in 21, 15 and 18 patients, respectively. Duplex Doppler sonography showed abnormal flow patterns in 37, 22 and 31 patients in the right, middle and left HV, respectively, thereby increasing the diagnostic yield by 40%. An abnormal waveform in one or more HV was present in all 37 patients. Uniphasic flow was the commonest abnormality and was seen in 22, nine and 14 patients, respectively, in the right, middle and left HV, while there was no flow in five, four and seven patients in the right, middle and left HV, respectively. Intrahepatic collaterals were seen in 35 of 37 patients (94.6%). Hepatopetal flow was found in the portal vein of 21 of 23 patients (91.3%), while flow was hepatofugal in one and portal vein thrombosis was found in another. CONCLUSION: Duplex Doppler sonography is a useful procedure which helps in the diagnosis of patients with Budd-Chiari syndrome.

Adolescent↗
PubMed1999

Aluminium-induced biphasic effect.

Increased bioavailability of aluminium has raised concerns about the toxic effect of aluminium. The cholinotoxic effect of aluminium is already well established. The biological response of an organism following exposure to a chemical may be biphasic. Although aluminium-induced biphasic change has been reported in diverse organ systems, the biphasic effect on cholinergic system has received less attention. In vitro and in vivo studies have demonstrated an aluminium-induced biphasic effect on the marker enzyme of cholinergic system, acetylcholinesterase. The biphasic effect of aluminium on the acetylcholinesterase enzyme activity may be due to the direct neurotoxic effect of the metal and the level of aluminium accumulated. Among various hypotheses, peroxidation-induced changes in the structure of membrane following aluminium accumulation seems to explain the biphasic effect of aluminium on acetylcholinesterase activity.

Acetylcholinesterase↗
PubMed1999

Steroid-regulated molecular markers of implantation.

The endometrium acquires the ability to implant the developing embryo within a specific time window, termed the "receptive phase." During this period the endometrium undergoes pronounced structural and functional changes induced by the ovarian steroids estrogen and progesterone, which prepare it to be receptive to invasion by the embryo. These steroid-induced molecules, when identified, may serve as useful markers of uterine receptivity. In the present article, we provide a brief description of the molecules that have emerged as candidate markers of steroid hormone action in rodents and humans during implantation.

Animals↗
PubMed1999

Comparison of the sensitivity of three psychophysical techniques to three manual materials handling task variables.

The primary objective of the study was to determine the absolute and relative sensitivity of three psychophysical techniques of physical stress determination (Borg's Scale, the Visual Analogue Scale, and the Body Part Discomfort Rating) in varied manual materials handling tasks. Ten young male and ten young female university students lifted a 22 kg box onto a shelf 132 cm high. The industrial-size box (40 x 20 x 20 cm) had two cut-out handles on the top middle of the two side panels. The shelf had restricted access allowing 5 and 10 mm clearance for access. The palletizing was performed in sagittal and 45 degrees asymmetrical postures under unlimited, 90% and 80% of stature headroom. The subjects lifted the box six times per minute for 5 min. After every lift the load was automatically delivered to the starting position. The 12 experimental conditions were randomized. Following each 5-min palletizing task the subjects were required to assess the immediately foregoing task on Borg's scale, the Visual Analogue scale, and a Body Part Discomfort Rating scale. All data were subjected to statistical analysis including multivariate analysis of variance and Scheffé post-hoc multiple range test. Borg's scale was able to discriminate between two clearances, two symmetries and the three headrooms (p < 0.001). The Visual Analogue scale was able to differentiate between two symmetries and three headrooms (p < 0.01), but the Body Part Discomfort Rating could not differentiate between any task conditions. Based on the study it is suggested that an appropriate match between the task demands and the basis of a psychophysical tool is essential for valid and reliable information.

Adult↗
PubMed1999

Persistence of alpha and beta isomers of endosulphan and endosulphan sulphate in diverse soils of India as influenced by flooding.

Laboratory studies were undertaken to evaluate the persistence of alpha-endosulphan, beta-endosulphan and endosulphan sulphate in four diverse soils under non-flooded and flooded conditions. Significant variations were observed in the extent of persistence of the three chemicals in different non-flooded soils with maximum persistence observed in Alfisol and the least in Mollisol having near neutral pH and higher organic matter. Degradation was more in all the flooded soils than in the non-flooded counterpart but in Vertisol under flooded and non-flooded conditions, the rate of degradation of endosulphan sulphate was found to be nearly same.

Chemical Phenomena↗
PubMed1999

RAPD profile based genetic characterization of chemotypic variants of Artemisia annua L.

The annual herbaceous plant, Artemisia annua L., belonging to family Asteraceae, is the natural source of the highly potent antimalarial compound, artemisinin, besides producing valuable essential oil. The plant is at present the sole commercial source for artemisinin production since all the chemical syntheses are non-viable. Therefore, economic and practical considerations dictate that plants with maximum content of artemisinin be found and/or ways to increase their artemisinin content be sought. The key to this selection and breeding is a comprehension of chemical and genetic variability and suitable selection(s) of elites from within the available population. In the present study, RAPD analyses of selected chemotypes from a decade old introduced population in India were carried out using arbitrary primers. The RAPD data clearly indicate the distinction amongst these plants. Further, the detection of highly polymorphic profiles (97 polymorphic markers out of a total of 101 markers) suggests the existence of very high levels of genetic variation in the Indian population despite geographical isolation and opens out a strong possibility of further genetic improvement for superior artemisinin content. UPGMA analyses of RAPD and phytochemical trait data indicate that the wide phytochemical diversity is included within the genetic diversity. These results further support the prospects for selection and breeding of superior artemisinin containing lines.

Antimalarials↗
PubMed1999

Caspases in developmental cell death.

Caspases are a family of evolutionarily conserved cysteine proteases that constitute the effector arm of the apoptotic machinery. Studies in Caenorhabditis elegans, Drosophila melanogaster, and mouse point to evolutionarily conserved caspase function in developmentally programmed cell death in metazoans. Whereas in the nematode all developmental cell death is mediated by a single caspase, in Drosophila and the mouse some caspases appear to regulate cell death in a spatio-temporally restricted manner. This article reviews what we currently know about the roles of various caspases in the execution of developmentally programmed cell death and what may be expected from future research in this field.

Animals↗