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Biomedical subjects

S Kaur

Publications and source records attributed to S Kaur.

At least 73 records · Page 4Linked to original sources
PubMed2000

Gastropathy and defense mechanisms in common bile duct ligated portal hypertensive rats.

Portal hypertensive gastropathy is associated with a broad spectrum of gastric mucosal damage inspite of decreased gastric acid secretion, suggestive of compromised endogenous protective mechanisms. To determine the mechanisms of damage in portal hypertensive gastropathy we measured lipid peroxidation, glutathione, antioxidant and lysosomal enzymes in gastric mucosal homogenates from male Wistar rats with elevated intrasplenic pulp pressure, eighteen days after common bile duct ligation. Thiobarbituric acid-reactive substances and lysosomal enzymes (beta-glucuronidase and acid phosphatase) were increased in the common bile duct ligated group as compared to the sham-operated group. The levels of antioxidant defense enzymes, superoxide dismutase, glutathione peroxidase, catalase and glutathione were decreased as compared to the sham-operated controls. Pre-operative vitamin E administration decreased mucosal lipid peroxidation increased the levels of antioxidant defense enzymes and lowered the lysosomal enzymes. The plasma vitamin E levels in this group were lower when compared to animals receiving it post-operatively. In conclusion, free radical and lysosomal enzyme mediated damage may play a role in portal hypertensive gastropathy.

Animals↗
PubMed2000

Plasma vascular endothelial but not fibroblast growth factor levels correlate with colorectal liver mestastasis vascularity and volume.

The extent to which plasma levels of angiogenic factors in healthy individuals and tumour volume-related variations in colorectal cancer affect the accuracy of circulating angiogenic factors as predictors of colorectal cancer vascularity is unknown. We used enzyme-linked immunosorbant assay to measure plasma vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) levels in colorectal liver metastasis (CLM) patients, and 'no cancer' controls. CLM volume was determined from computerized tomography scans, and tumour vessel count and vessel volume from anti-endothelial antibody-stained biopsies. There was a significant (P= 0.03) increase in plasma VEGF level in 29 CLM patients (median 180.3 pg/ml(-1), iqr 132.5-284.8 pg/ml(-1) compared with 19 controls (median 125.8 pg/ml(-1), iqr 58.2-235.9 pg/ml(-1). There were significant correlations between plasma VEGF and tumour vessel count (r = 0.66, P = 0.03), tumour vessel volume (r= 0.59, P = 0.03), and CLM volume (r= 0.53, P = 0.03). A VEGF level in the upper quartile of the plasma VEGF distribution had a 70% sensitivity and 75% specificity in predicting an upper quartile liver metastasis tumour vessel count. No relation was identified between CLM and plasma bFGF levels. Plasma VEGF level predicted CLM vascularity, despite an overlap with normal levels and tumour volume-related variations.

Biomarkers, Tumor↗
PubMed2000

Further observations and characterization of monoclonal antibodies reacting with B cell alloantigens associated with rheumatic fever and rheumatic heart disease.

Elevated levels of B lymphocytes with a unique surface alloantigen have been reported to be characteristic of patients with acute rheumatic fever or rheumatic heart disease. Mouse monoclonal antibodies (mAbs) to this alloantigen have been proposed as being useful in identifying individuals at risk for the development of these sequelae of group A streptococcal infection. However, previous studies have suggested that the discriminating ability of the mAbs was highest when the mAbs were made by using lymphocytes from the same ethnic population. To confirm and extend this observation, additional mouse mAbs were developed and their properties defined. These three mAbs-PG-12A, PG-13A, and PG-20A-reacted with B cells from more than 90% of North Indian patients with acute rheumatic fever or rheumatic heart disease. Each of these three new mAbs identified the highest levels of reactive B cells in patients with active acute rheumatic fever. Lower levels of positive reacting lymphocytes were found in individuals with quiescent chronic rheumatic heart disease, and markedly reduced percentages of reactive cells were observed in normal control subjects. The proportion of reactive lymphocytes in individual patients varied according to which of the three was tested, suggesting the possibility of a spectrum of "rheumatic" epitopes in susceptible individuals. The data further suggested that enhanced discriminatory ability for identifying "at-risk" susceptible patients could be obtained by testing with a combination of mAbs. If reduction in the incidence of acute rheumatic fever can be facilitated by early identification of susceptible individuals, accurate and sensitive detection of a marker antigen would result in more cost-effective public health measures. Additional population studies are required to more precisely define and confirm these detection techniques.

Adult↗
PubMed2000

Identifying a site for maximum delivery of oxygen to transplanted cells.

For in vivo cell implantation techniques to be successful, the energy and metabolic substrate requirement of the cells being grown must be met. Certain cells with high-energy requirements (e.g., hepatocytes, pancreatic island cells) experience a high degree of cell death after implantation due to a limited supply of oxygen. We proposed that the pleural cavity might be an oxygen-rich environment and hence an excellent site for cell implantation. To test the hypothesis that the delivery of oxygen to the pleural cavity is directly proportional to the inspired oxygen concentration we measured the pO(2) of saline instilled in the pleural cavity as compared to that of the peritoneal cavity. We postulated that the physiologic basis for any difference was the result of direct diffusion of oxygen into the pleural space across the alveoli. The study was conducted on sheep (n = 6), after induction of general anesthesia, in two phases, control and experimental. Saline was instilled into the peritoneal and pleural cavities via catheters, after equilibration at given FiO(2), the pO(2) of the paline aspirated from the two cavities was compared. In the experimental group, animals were sacrificed (no circulation) and ventilated. The same sequence of steps as in the control phase were repeated. In the control group, the pO(2) of saline aspirated from the pleural cavity approached the arterial pO(2) at all FiO(2) levels. The pO(2) of the peritoneal saline aspirate fell over time. In the experimental phase (no circulation), the pO(2) of the pleural cavity saline rose to >400 mm Hg. We conclude that this is a result of direct diffusion and is a potential source of unlimited oxygen supply not dependent on vascular supply.

Animals↗
PubMed2000

Growth suppression of human transformed cells by treatment with bark extracts from a medicinal plant, Terminalia arjuna.

We have investigated the effects of acetone and methanol extracts of a medicinal plant, Terminalia arjuna, on the growth of human normal fibroblasts (WI-38), osteosarcoma (U2OS), and glioblastoma (U251) cells in vitro. We found that both extracts at 30 microg and 60 microg/ml concentrations inhibit the growth of transformed cells; the growth of normal cells was least affected. Although the transformed cells appeared to have fragmented nucleus by Hoechst staining, no deoxy-ribonucleic acid laddering effect was observed. In response to the extract treatment, the tumor suppressor protein, p53, was induced in U2OS but not in U251 and WI-38 cells. A cyclin-dependent kinase inhibitor, p21WAF1, was induced in transformed cells only. The study suggests that the bark extract of medicinal plant, T. arjuna, has components that can induce growth arrest of transformed cells by p53-dependent and -independent pathways.

Apoptosis↗
PubMed2000

Susceptibility of species A, B, and C of Anopheles culicifacies complex to Plasmodium yoelii yoelii and Plasmodium vinckei petteri infections.

The comparative susceptibilities of colonized species A, B, and C of Anopheles culicifacies complex and Anopheles stephensi were determined for 2 rodent malaria parasites Plasmodium vinckei petteri and Plasmodium yoelii yoelii. All the 3 members of the complex were found to support complete sporogony with varying success. Controls, A. stephensi, become readily infected, with >70% developing oocysts. Of the test groups, species A had the highest percentage of mosquitoes with oocysts (>25%) and sporozoites (>15%). Anopheles culicifacies species B were least susceptible; less than 10% had oocysts and sporozoites in the salivary glands. The results demonstrate that A. culicifacies species A is most susceptible and species B is least susceptible to infections with both the parasites.

Animals↗
PubMed2000

Kinetics of humoral & cellular immune responses in experimental cysticercosis in pigs infected with Taenia solium.

Studies were undertaken to assess the kinetics of antibody responses, lymphocyte transformation to Taenia solium larval antigens (crude soluble extract antigen and antigen B), and T cell subpopulation in piglets following experimental infection. Cysticercosis was established in 1-2 month old piglets after feeding 5,00,000 T. solium eggs per pig. The anti-CD4 and anti-CD8 monoclonal antibodies against swine T cells were raised indigenously. It was observed that at 60 days post infection (PI) there was a significant increase (P < 0.01) in CD4+ T cells without any change in CD8+ T cells. Increased 3H-thymidine uptake was found in infected piglets at 45 days PI using both CSE and antigen B. Kinetics of antibody responses indicated significant increase (P < 0.01) at 15 days PI (with CSE antigen) and 30 days PI (with antigen B) by ELISA. This increase persisted till 90 days PI (the time up to which the animals were followed). It was also observed that the cellular mechanisms were triggered in late stage (60 days PI) as compared to humoral responses (15-30 days PI) and may persist longer as seen by both lymphocyte transformation and T cell subpopulation studies. The study suggests that in cysticercosis, both humoral and cellular mechanisms may play a role in the host defences.

Animals↗
PubMed1999

A mouse gene knockout model for juvenile ceroid-lipofuscinosis (Batten disease).

The human hereditary ceroid-lipofuscinoses are a group of autosomal recessively inherited diseases characterized by massive accumulations of autofluorescent lysosomal storage bodies in the cells of many tissues and by neuronal degeneration throughout the central nervous system. There are a number of clinically and genetically distinct forms of ceroid-lipofuscinosis, the most common of which is the juvenile type, also known as Batten disease and CLN3. To study the mechanisms that lead to pathology in CLN3 and to evaluate potential therapies, a mouse model has been generated by targeted disruption of the mouse ortholog of the CLN3 gene (Cln3). As in affected humans, mice homozygous for the disrupted Cln3 allele show accumulation of autofluorescent storage material in neurons and other cell types. The storage material consists of membrane-bounded intracellular inclusions with ultrastructural features typical of the ceroid-lipofuscinoses. The accumulation of this storage material validates the Cln3 knockout mice as a model for the human disorder.

Animals↗
PubMed1999

Prolactin controls mammary gland development via direct and indirect mechanisms.

The inactivation of the prolactin receptor gene by homologous recombination has made it possible to investigate the role of prolactin signaling in mammary gland development without resort to ablative surgery of the endocrine glands. In knockout mice lacking the prolactin receptor, mammary development is normal up to puberty. Subsequently, the ducts branch less frequently than those of wild-type animals. While terminal end buds differentiate to alveolar buds in wild-type females by the end of puberty, in knockout females terminal end bud-like structures persist at the ductal ends. To distinguish between the developmental defects that are intrinsic to the epithelium and those that result from systemic endocrine alterations in prolactin receptor knockout mice, mammary epithelium from prolactin receptor knockouts was transplanted into mammary fat pads of wild-type mice. In virgin mice, the knockout epithelial transplants developed normally at puberty, indicating an indirect effect of prolactin on ductal development. Prolactin receptor knockout females are infertile due to multiple reproductive defects, but epithelial transplants allowed us to assess the extent to which the absence of prolactin receptor is limiting, under systemic conditions that allow full mammary gland development. During pregnancy, the prolactin receptor knockout transplants showed normal side branching and the formation of alveolar buds, but no lobuloalveolar development. Thus, prolactin affects mammary morphogenesis in two different ways: it controls ductal side branching and terminal end bud regression in virgin animals via indirect mechanisms, but acts directly on the mammary epithelium to produce lobuloalveolar development during pregnancy.

Animals↗
PubMed1999

Genotoxicity of wastewater samples from sewage and industrial effluent detected by the Allium root anaphase aberration and micronucleus assays.

The genotoxicity of wastewater samples from sewage, and industrial effluent from the Amritsar, India, area were investigated using the Allium micronucleus and anaphase aberration assays. Raw sewage samples and acetone extracts of the dehydrated sewage were use for treatment of the Allium roots. Industrial effluents were collected and stored in the form of sludge (semi-dried matter). The acetone extracts of the sludge samples were also used for treatment of the Allium roots. From the Allium root micronuclei tests on the sewage extracts, no significant increase in the number of micronuclei was found in comparison with negative controls. All the other extracts from industrial effluent showed positive responses both in the micronucleus and anaphase aberration assays.

Allium↗
PubMed1999

Importance of the carboxyl terminus in the folding and function of alpha-hemolysin of Staphylococcus aureus.

The physical state of two model mutants of alpha-hemolysin (alphaHL), alphaHL(1-289), a carboxyl-terminal deletion mutant (CDM), and alphaHL(1-331), a carboxyl-terminal extension mutant (CEM), were examined in detail to identify the role of the carboxyl terminus in the folding and function of native alphaHL. Denatured alphaHL can be refolded efficiently with nearly total recovery of its activity upon restoration of nondenaturing conditions. Various biophysical and biochemical studies on the three proteins have revealed the importance of an intact carboxyl terminus in the folding of alphaHL. The CDM exhibits a marked increase in susceptibility to proteases as compared with alphaHL. alphaHL and CEM exhibit similar fluorescence emission maxima, and that of the CDM is red-shifted by 9 nm, which indicates a greater solvent exposure of the tryptophan residues of the CDM. In addition, the CDM binds 8-anilino-1-naphthalene sulfonic acid (ANS) and increases its fluorescence intensity significantly unlike alphaHL and CEM, which show marginal binding. The circular dichroism studies point that the CDM possesses significant secondary structure, but its tertiary structure is greatly diminished as compared with alphaHL. These data show that the CDM has several of the features that characterize a molten globule state. Experiments with freshly translated mutants, using coupled in vitro transcription and translation, have further supported our observations that deletion at the carboxyl terminus leads to major structural perturbations in the water-soluble form of alphaHL. The studies demonstrate a critical role of the carboxyl terminus of alphaHL in attaining the native folded state.

Bacterial Toxins↗
PubMed1999

Size fractionation of bacterial capsular polysaccharides for their use in conjugate vaccines.

We have developed a chromatographic method suitable for the fractionation of polysaccharides having a negatively charged group. The method permits the removal of all those polysaccharide fragments having a short sequence and which are likely unsuitable for conjugate vaccine construction. The selected polysaccharide fragments can be used to produce glycoconjugate vaccines containing a restricted saccharide polydispersion. We have applied this chromatographic method to three different antigens, Haemophilus influenzae type b and Neisseria meningitidis group A and group C polysaccharides. The method is easily adapted for manufacturing purposes.

Antigens, Bacterial↗
PubMed1999

Calcium metabolism in pre-eclampsia.

OBJECTIVES: To study calcium metabolism in pre-eclampsia and normotensive gravid women. METHOD: Ten milliliters of heparinized blood samples and 24-h urine samples were collected from 50 pre-eclamptic and 50 normotensive primigravidae. Blood samples were studied for calcium uptake, intracellular calcium level and calcium-dependent adenosine triphosphatase activity of red blood cell ghost. Urinary calcium excretion was estimated from the 24-h urine samples. These values were compared in the two groups. RESULTS: The mean gestational age at recruitment was similar in both the groups. The mean maternal age was 24.28 +/- 2.41 years in pre-eclamptic and 23.48 +/- 4.16 years in normotensive women. In pre-eclampsia 24-h urinary calcium excretion (71.20 +/- 22.95 mg/day) and calcium-dependent ATPase activity (10.78 +/- 2.40 nmol/Pi/mg protein/min) was significantly lower compared to normotensive primigravidae (calcium excretion = 189.24 +/- 57.06 mg/day; Ca2+-dependent ATPase = 12.64 +/- 2.42 nmolPi/mg /protein per min; P < 0.001). Intracellular calcium levels and calcium uptake at 10 min by red blood cells were significantly higher in pre-eclampsia (P < 0.05). Calcium uptake by red blood cells at 20 and 30 min was similar in both groups. CONCLUSION: Pre-eclampsia is associated with increased levels of intracellular calcium, decreased calcium-dependent ATPase activity of erythrocytes and hypocalciuria.

Adult↗