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Biomedical subjects

S Kaur

Publications and source records attributed to S Kaur.

At least 163 records · Page 9Linked to original sources
PubMed1993

HLA A2.1-restricted cytotoxic T cells recognizing a range of Epstein-Barr virus isolates through a defined epitope in latent membrane protein LMP2.

Cytotoxic T-lymphocyte (CTL) responses induced by persistent Epstein-Barr virus (EBV) infection in normal B-lymphoid tissues could potentially be directed against EBV-positive malignancies if expression of the relevant viral target proteins is maintained in tumor cells. For malignancies such as nasopharyngeal carcinoma and Hodgkin's disease, this will require CTL targeting against the nuclear antigen EBNA1 or the latent membrane proteins LMP1 and LMP2. Here we analyze in detail a B95.8 EBV-reactivated CTL response which is specific for LMP2 and restricted through a common HLA allele, A2.1. We found that in vitro-reactivated CTL preparations from several A2.1-positive virus-immune donors contained detectable reactivity against A2.1-bearing target cells expressing either LMP2A or the smaller LMP2B protein from recombinant vaccinia virus vectors. Peptide sensitization experiments then mapped the A2.1-restricted response to a single epitope, the nonamer CLGGLLTMV (LMP2A residues 426 to 434), whose sequence accords well with the proposed peptide binding motif for A2.1. Most Caucasian and African virus isolates (whether of type 1 or type 2) were identical in sequence to B95.8 across this LMP2 epitope region, although 2 of 12 such isolates encoded a Leu-->Ile change at epitope position 6. In contrast, most Southeast Asian and New Guinean isolates (whether of type 1 or type 2) constituted a different virus group with a Cys-->Ser mutation at epitope position 1. CTLs raised against the B95.8-encoded epitope were nevertheless able to recognize these variant epitope sequences in the context of A2.1 whether they were provided exogenously as synthetic peptides or generated endogenously in B cells transformed with the variant viruses. A CTL response of this kind could have therapeutic potential in that it is directed against a protein expressed in many EBV-positive malignancies, is reactive across a range of virus isolates, and is restricted through a relatively common HLA allele.

Amino Acid Sequence↗
PubMed1993

Concurrent skin and nerve histology in leprosy and its role in the classification of leprosy.

Concurrent skin and nerve histology was evaluated in 60 leprosy patients (25 BT, 28 BL and 7 LL). The twin aims were to study the comparative histology and the usefulness of nerve histology in the classification of the disease. In BT patients, clinical and histological classification was in agreement in 11 (44%) skin and 17 (68%) nerve biopsies. Concurrent skin and nerve histology was in consonance in 14 (56%) BT patients, while in 6 (24%) patients, only nerve histology was helpful in the classification of the disease, the skin histology being non-specific. Nerve histology was classified as BL in 3 (12%) BT patients, the skin histology was non-specific. In the BL group, the histology of 23 (82.4%) nerve biopsies correlated with the clinical classification, in contrast to skin histology which correlated with clinical assessment in 19 (68%) patients only. In the LL patients, the histology of nerve correlated with the clinical classification in 5 patients (71.4%), compared to histology of the skin in 4 (57%) patients only. The GF was higher in the nerves than in the skin throughout the leprosy spectrum (BT, BL, LL); the difference was, however, marginal in BL leprosy. The average bacteriological index (BI) was higher in nerves (4+) compared to that of skin histology and slit skin smears (3+) in BL leprosy. There was, however, no difference in the BI of the slit skin smears, skin and nerve biopsies in lepromatous leprosy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Transport of amino-acids across renal brush border membrane vesicles in Mycobacterium leprae infected Swiss albino mice--effect of Convit vaccine.

Brush border membrane vesicles prepared from kidneys of Mycobacterium leprae infected (non-vaccinated) and vaccinated-infected Swiss albino mice were used to assess the effect of Convit's combined vaccine (BCG + M. leprae) on amino acid transport activity across the tubular basement membrane. The protective effect of Convit's vaccine was more pronounced with respect to the uptake of L-alanine than L-aspartate. Uptake of L-lysine showed no significant difference in the different groups. Footpad counts followed characteristic growth curves in the non-vaccinated infected group but showed a lag in the development of peak levels in the vaccinated group. Further Convit's vaccine appeared to have a protective effect on renal impairment in the mouse model of leprosy in the initial stages of infection only, as indicated by the transient reversal of amino acid uptake and a diminution in the footpad counts induced by M. leprae infection. No significant (P > 0.05) protective effect of the vaccine was found in the advanced disease state.

Amino Acids↗
PubMed1993

Cutaneous sarcoidosis masquerading as relapsed borderline tuberculoid leprosy?

A patient with cutaneous sarcoidosis is presented. The patient was diagnosed initially as borderline tuberculoid leprosy downgrading to borderline lepromatous leprosy and received a full 2 years of World Health Organization multibacillary drug treatment (MDT). Bilateral hilar lymphadenopathy on chest X-ray and cutaneous anergy manifested by negative Mantoux, candidin and trichophytin skin tests suggested the diagnosis of sarcoidosis. Histopathology confirmed this diagnosis. The subcutaneous nodule seen in this patient is a rare type of cutaneous sarcoidosis.

Biopsy↗
PubMed1993

Incidence of fungal infection in extra hepatic biliary stone disease.

50 patients undergoing biliary surgery were studied to know the incidence of fungal infection. Samples such as bile & stones for mycological analysis were obtained from the gall bladder & Common Bile Duct (CBD) at the time of surgery. Fungal aetiology was established in 8 (16.3%) cases. Incidence of fungal infection was more (12.2%) in gall bladder bile as compared to 6% in common bile duct bile. The nucleus of stone yielded growth of fungus in only 2 (4.6%) cases. Candida albicans, C. tropicalies, C, kruzei, Penicillium and Aspergillus were the common fungal isolates in the present study.

Aspergillosis↗
PubMed1993

Toxicity of exposed aluminium phosphide.

Poisoning by the partially or fully exposed compound of aluminium phosphide (ALP) is becoming common, Fifty patients with history of ingestion of ALP either in the form of broken tablets or granular powder were included in this study for analysis of systemic effects and outcome. Forty patients (Gr. I) consumed broken or granular form of tablets. Ten patients (Gr. II) consumed only powder form of tablets from an old container. 30 patients in group-I developed mild hypotension (BP 80-90 mm Hg). 4 patients (10%) developed ECG changes and mild metabolic acidosis. One patient died constituting 2.5% mortality rate. The patients of group-II neither developed any systemic effects nor showed any mortality. The aim of the study is to differentiate these cases from patients who consume active, fresh compound where mortality rate will be much higher.

Acidosis↗
PubMed1993

Effect of pH and sodium ions on intestinal uptake of lysine in rats.

Intestinal uptake of lysine in rats progressively decreased with an increase in pH from 5.2 to 8.5, both in the presence and absence of Na+ ions. At pH 5.2 lysine uptake was 30-35% more than that at neutral pH. Na+ activated lysine uptake by 40-50% at pH 5.2 and it was increased to 110-120% at neutral pH. The observed increase in lysine uptake in response to Na+ and H+ gradients was due to enhanced maximal velocity (Vmax), with little change in affinity constant (Kt). Arrhenius analysis revealed a biphasic curve for lysine uptake with transition temperature (Tc) around 20 degrees C (24 degrees C at pH 5.2 in presence of Na+). The energy of activation (Ea) below (16.1-23.4 Kcal/mole) and above (6.7-8.6 Kcal/mole) the Tc was similar at pH 5.2 and 7.0 both in the presence and absence of Na+ ions. The sensitivity of lysine uptake to various inhibitors was also dependent upon pH and Na+ ions.

Animals↗
PubMed1992

Dominant mutation of the murine Hox-2.2 gene results in developmental abnormalities.

Genes carrying the homeobox were originally identified in Drosophila, in which they are now known to play key roles in establishing segmentation patterns and in determining segment identities. A number of genes with striking homology to the Drosophila homeobox genes have now been found in the mouse genome, and mutational analysis is beginning to shed light on their function in mammalian development. To understand better the developmental significance of the murine Hox-2.2 gene, we have generated gain of function mutants by using the chicken beta-actin promoter to drive ubiquitous expression in transgenic mice. The resulting Hox-2.2 misexpression produces early postnatal lethality as well as craniofacial and axial skeletal perturbations that include open eyes at birth, cleft palate, micrognathia, microtia, skull bone deficiencies, and structural and positional alterations in the vertebral column. We repeatedly observe complete or partial absence of the supraoccipital bone and malformations of the exoccipital and the basioccipital bones. These results suggests a role for the Hox-2.2 gene in specifying positional identity along the anterior-posterior axis.

Abnormalities, Multiple↗
PubMed1992

The primary structure of fatty-acid-binding protein from nurse shark liver. Structural and evolutionary relationship to the mammalian fatty-acid-binding protein family.

The primary structure of a fatty-acid-binding protein (FABP) isolated from the liver of the nurse shark (Ginglymostoma cirratum) was determined by high-performance tandem mass spectrometry (employing multichannel array detection) and Edman degradation. Shark liver FABP consists of 132 amino acids with an acetylated N-terminal valine. The chemical molecular mass of the intact protein determined by electrospray ionization mass spectrometry (Mr = 15124 +/- 2.5) was in good agreement with that calculated from the amino acid sequence (Mr = 15121.3). The amino acid sequence of shark liver FABP displays significantly greater similarity to the FABP expressed in mammalian heart, peripheral nerve myelin and adipose tissue (61-53% sequence similarity) than to the FABP expressed in mammalian liver (22% similarity). Phylogenetic trees derived from the comparison of the shark liver FABP amino acid sequence with the members of the mammalian fatty-acid/retinoid-binding protein gene family indicate the initial divergence of an ancestral gene into two major subfamilies: one comprising the genes for mammalian liver FABP and gastrotropin, the other comprising the genes for mammalian cellular retinol-binding proteins I and II, cellular retinoic-acid-binding protein myelin P2 protein, adipocyte FABP, heart FABP and shark liver FABP, the latter having diverged from the ancestral gene that ultimately gave rise to the present day mammalian heart-FABP, adipocyte FABP and myelin P2 protein sequences. The sequence for intestinal FABP from the rat could be assigned to either subfamily, depending on the approach used for phylogenetic tree construction, but clearly diverged at a relatively early evolutionary time point. Indeed, sequences proximately ancestral or closely related to mammalian intestinal FABP, liver FABP, gastrotropin and the retinoid-binding group of proteins appear to have arisen prior to the divergence of shark liver FABP and should therefore also be present in elasmobranchs. The presence in shark liver of an FABP which differs substantially in primary structure from mammalian liver FABP, while being closely related to the FABP expressed in mammalian heart muscle, peripheral nerve myelin and adipocytes, opens a further dimension regarding the question of the existence of structure-dependent and tissue-specific specialization of FABP function in lipid metabolism.

Amino Acid Sequence↗
PubMed1992

Lens structures exist transiently in development of transgenic mice carrying an alpha-crystallin-diphtheria toxin hybrid gene.

The development of lens structures in transgenic mice (lnl mice) which carry the diphtheria toxin A chain-coding sequence under the control of the alpha-crystallin promoter is examined here in detail. The initial stages of lens development during embryonic days 10.5 to 12.5 (E10.5-E12.5), including the invagination of the surface ectoderm to form a lens vesicle, closure of the vesicle to form a lens cup, and initial appearance of the lens itself, appeared identical in histologic analyses of lnl mice and genotypically wild-type littermate controls. However, by E12.5, cells in the central posterior lens of developing lnl mice appeared to be vacuolated and undergoing necrosis. This necrosis was quite prominent at E14.5 and the overall lens size was significantly reduced. The lenses of lnl mice continued to be present but were significantly smaller throughout embryonic development. The cells of these lenses were capable of undergoing biochemical differentiation, reacting with antibodies to both alpha- and beta-/gamma-crystallin. alpha-Crystallin expression was initiated at the appropriate time (E10.5) and maintained in most cells of lnl lenses. The expression of beta-/gamma-crystallins was surprising as these crystallins are expressed later in lens development after normal expression of alpha-crystallin and after the anticipated time of expression of the diphtheria toxin transgene. Despite extensive necrosis and cell death, lens structures persisted in lnl mice and disappeared only in the early postnatal period between days 3 and 6. Throughout the perinatal period, the remaining lens cells expressed both alpha- and beta-/gamma-crystallins. Prenatal development of the retina and ciliary body was relatively normal although the eye was significantly reduced in overall size. Some additional developmental defects were noted including persistent hyaloid artery and thickened cornea. In the perinatal period the rapidly expanding retina filled the entire eye leaving essentially no anterior or posterior chamber. These results clearly indicate that lens cells which are the target of diphtheria toxin-mediated cell ablation techniques persist for a significant time during development and thus place limitations on the interpretations of results obtained using this technique.

Animals↗
PubMed1992

Effect of sodium stibogluconate and pentamidine on in vitro multiplication of Leishmania donovani in peritoneal macrophages from infected and drug-treated BALB/c mice.

The in vitro antileishmanial activity of sodium stibogluconate (SSG) and pentamidine in peritoneal macrophages from three different groups of animals (i.e. normal, Leishmania donovani-infected and drug-treated BALB/c mice) is reported. Peritoneal macrophages were extracted from all these animals and infected in vitro with L. donovani promastigotes. After 24 h, the infected macrophages (with amastigotes) were exposed to various concentrations of SSG (10-90 micrograms/mL) and pentamidine (0.1-5.0 micrograms/mL). The in vitro infection could be cured readily with 80 micrograms/mL of SSG and 4 micrograms/mL of pentamidine in macrophages from normal animals. But even higher dosages of these drugs added in vitro could not reduce the amastigote loads in macrophages from infected animals. In contrast, incubation in vitro of infected macrophages with very low dosages of these drugs (40 micrograms/mL of SSG and 1.0 mu/mL of pentamidine) could eliminate the parasites present within macrophages obtained from drug-treated animals. This was probably because the macrophages from drug-treated animals tackled the parasites themselves by their microbicidal mechanisms and the in vitro infection was tackled by the drug in vitro. This implies that a well-developed specific immunity in leishmaniasis helps in the antileishmanial activity of these drugs.

Animals↗
PubMed1992

Identification of N2-substituted 2'-deoxyguanosine-3'-phosphate adducts detected by 32P-postlabeling of styrene-oxide-treated DNA.

Styrene-7,8-oxide, a metabolite of the industrial chemical styrene, was reacted with calf thymus DNA. Six adducts were detected by 32P-postlabeling. The two diastereomers of N2-(2-hydroxy-1-phenylethyl)-2'-deoxyguanosine-3'-phosphate and the corresponding N-1 substituted compounds were isolated from the aqueous reaction mixture of 2'-deoxyguanosine-3'-phosphate and styrene-7,8-oxide (pH 10.5) and characterized by liquid secondary-ion and four-sector tandem mass spectrometry, ultraviolet, circular dichroism, and fluorescence spectrophotometry, and 32P-postlabeling. Co-chromatography of the DNA-styrene-7,8-oxide reaction products with the synthetic standards showed that adduct no. 6 arose as a result of aralkylation at the N2-exocyclic site of the guanine base. The recovery of the N2-adduct was dependent on the concentration of the solvent used during octadecylsilyl chromatography. These studies revealed that the N2-guanosine derivatives are the major products of the reaction of DNA and styrene-7,8-oxide in vitro detected by 32P-postlabeling.

Autoradiography↗