Biomedical subjects
Publications and source records attributed to A Goyal.
Tuberculosis of the pharynx is less common than tuberculosis of the larynx. We present a rare case of tuberculosis of the pyriform fossa which clinically masqueraded as a malignancy. Our patient showed a prompt improvement in symptoms after commencing antitubercular treatment.
A Monte Carlo model was used to simulate specimen-electron beam interactions relevant to electron back-scattered diffraction (EBSD). Electron trajectories were calculated for a variety of likely experimental conditions to examine the interaction volume of the incident electrons as well as that of the subset of incident electrons that emerge from the specimen, i.e., back-scattered electrons (BSEs). The spatial resolution of EBSD was investigated as functions of both materials properties, such as atomic number, atomic weight, and density, and experimental parameters, such as specimen thickness, tilt, and incident beam accelerating voltage. These simulations reveal that the achievable spatial resolution in EBSD is determined by these intrinsic and extrinsic parameters.
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This is a rare case of involvement of knee joint by an arteriovenous malformation. A nine year old girl had recurrent monoarticular pain and swelling of long duration and had been treated as juvenile rheumatoid arthritis. Angiographic and histological features suggested an arteriovenous malformation of lower thigh with knee joint involvement.
The treatment of Leuconostoc mesenteroides NRRL B-512F dextransucrase with lysine specific reagent, pyridoxal 5'-phosphate (PLP) at pH 5.2 and 30 degrees C resulted in the loss of enzyme activity. The inactivation by PLP could be reversed completely by dilution or dialysis. Sucrose as well as acceptor substrates, glucose and dextran protected the enzyme against inactivation by PLP. A statistical, kinetic analysis of the inactivation by PLP showed that one lysine residue is essential for the enzyme activity. All these results showed that one lysine residue present at the active is essential for the activity of dextransucrase.
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The rodent intestinal mucosa undergoes a remarkable morphogenesis as the crypt-villus axis is formed. Endoderm-mesenchymal interactions play a critical role in this process. Epimorphin is a mesenchymal protein postulated to play a role in lung and skin morphogenesis. The rat homologue, syntaxin 2, belongs to a family of integral membrane proteins that function in vesicle docking and fusion. To clarify its role in fetal gut morphogenesis, epimorphin expression was examined during ontogeny, in an isograft model of ischemic injury and mucosal repair, and during intestinal adaptation after small bowel resection. Epimorphin/syntaxin 2 mRNA levels were increased in fetal gut during lumen formation and villus morphogenesis. mRNA levels remained elevated in the first 2 wk after birth and then declined at weaning. In situ hybridization showed epimorphin/syntaxin 2 mRNA in gestational day 14 (G14) and G15 intestinal mesenchymal cells and in the mucosal lamina propria during villus formation. Epimorphin/syntaxin 2 mRNA expression increased during villus repair in the isograft. In contrast, in the early stages of intestinal adaptation after small bowel resection, epimorphin/syntaxin 2 mRNA expression was suppressed in the adapting gut. We conclude the cell-specific and temporal patterns of epimorphin expression in the models used in this study suggest a role in the morphogenesis of the crypt-villus axis.
The kinetics of inactivation of Leuconostoc mesenteroides NRRL B-512F dextransucrase by o-phthalaldehyde showed that the reaction followed pseudo-first order reaction. The loss of enzyme activity was concomitant with an increase in fluorescence at 417 nm indicating that the inhibition involved the reaction of an epsilon-amino and a thiol group of the enzyme leading to the formation of an isoindole derivative. The stoichiometry of inactivation showed that one isoindole derivative was formed per enzyme molecule. The substrates sucrose and glucose provided protection against o-phthalaldehyde inactivation which was also corroborated by fluorescence studies. Dextransucrase was not inactivated by 5,5'-dithiobis(2-nitrobenzoic acid), showing that the cysteine present in close proximity to the lysine is not essential for enzyme activity. Denaturation of dextransucrase by urea or heat treatment prior to o-phthalaldehyde addition resulted in a decrease of fluorescence intensity indicating that the native conformation of the enzyme is essential for isoindole derivative formation. These results established that a lysine residue is present at the active site and is essential for the activity of dextransucrase.
OBJECTIVE: To evaluate the intellectual, psychoeducational and social maturity of a cohort of unimpaired asphyxiated survivors beyond 5 years of age. DESIGN: Case control study on hospital based cohorts on a longitudinal follow up at High Risk and Well Baby Clinics of a teaching hospital. METHODS: The demographic data of these children was recorded. A detailed physical examination was performed. The tests of cognition included the Stanford Binet and the Raven's Progressive matrices. Academic achievement was evaluated by the Wide range achievement test-Revised (WRAT-R). Assessment of visuo-motor integration was done by the Bender Gestalt Test. The proportion of children having soft neurological signs was determined. Vineland Social Maturity Scale was performed on all children. RESULTS: Fifty-four asphyxiated and 57 matched control children participated in the study. Of the 54 asphyxiated children, 27 were tested at a mean age of 7.2 +/- 1.6 years (Group 1) and 27 were tested at a mean age of 10.9 +/- 1.52 years (Group 2). The asphyxiated children as a group performed in the normal range on tests of cognition and academic achievement but were significantly disadvantaged (p < 0.005) as compared to controls. A higher percentage of asphyxiated children had low scores on the Bender Gestalt Test as compared to controls but the difference was not significant. A significantly higher proportion of asphyxiated children of both the groups showed the presence of soft neurological signs as compared to controls. Approximately 11% of the asphyxiated children performed in the abnormal range in the Vineland Social Maturity Scale. CONCLUSION: Cognitive abilities of asphyxiated children beyond the age of 5 years are impaired in comparison to controls, emphasizing the need for early detection and referral for special education.
Ten patients of chronic obstructive pulmonary disease were studied for changes in ultrastructure of the glomeruli, serum immunoglobulin and complement levels. The glomeruli showed proliferation in the mesangium in 90% patients and electron dense deposits in the mesangium in 30% patients. IgA and IgG were usually elevated whereas complements were usually depressed in most of these patients. It is suggested that repeated respiratory infections in these subjects may be responsible for mesangioproliferative type of glomerulonephritis, high IgA and IgG levels. The complements are activated and they take part in immune complex formation getting deposited in mesangium.
A pilot study was carried out in five mandibular primary molars using calcium hydroxide (Ca(OH)2) Paste as root canal filling material to find out an alternative to the routinely used zinc oxide eugenol (ZnOE), which is non-resorbable and causes deflection of succedaneous teeth. The six month clinical and radiographic follow-up carried out at 2 months interval, revealed that the treated teeth with Ca(OH)2 as root canal filling material were successful, showing no pain and tenderness to percussion. A tendency for decrease in size of radiolucency was seen. Two teeth showed complete healing of the periradicular radiolucency. Depletion of Ca(OH)2 paste was seen from the root canals even prior to physiological resorption of roots in 2 out of 5 treated teeth.
There is a paucity of data on the amount of fluoride absorbed in humans from whole cooked food; especially a combination of different foods taken at regular meal times. The present study was thus aimed at estimating the amount of fluoride present and absorbed in humans from four regional representative meals viz. North Indian Vegetarian, North Indian Non-vegetarian, South Indian and East Indian. Twenty five healthy human volunteers aged 22-35 years participated in the study and each diet was tested on five volunteers. Each test diet was weighed into six equal parts, one part was kept for estimation of fluoride content and remaining five were given one each to the five test subjects in each of the four test diet groups. Eight hour plasma fluoride profiles were then studied after ingestion of weighed quantity of test diets and means calculated. The bioavailability of fluoride from these diets was evaluated in relation to that of sodium fluoride in solution form. The amount of fluoride estimated in different test diets varied between 1.53 - 10.0 mg. The bioavailability was found to be 1.6 per cent for north Indian vegetarian diet, 7.5 per cent for east Indian diet, 14.4 per cent for north Indian nonvegetarian diet and 31.7 per cent for south Indian diet, however, the amount of F(mg) absorbed in plasma from these diets was found to be low i.e. 0.06 mg, 0.75 mg, 0.72 mg and 0.48 mg respectively.
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The triple mutant K89L/A163G/S380A (inactive with glutamate but active with L-Nle and L-Met) and C320S (fully active with glutamate, entirely inactive with L-Nle and L-Met, and also lacking reactive cysteine) mutant of glutamate dehydrogenase (EC 1.4.1.2) of Clostridium symbiosum could be completely denatured by urea with the loss of structure and activity. The mutants denatured by urea could be reassociated to give stable hexamers with recovery of activity of approximately 67% by dilution in 0.1 M potassium phosphate buffer (pH 7.0) containing 2 mM NAD+. The native, urea-denatured, and renatured states of mutant enzymes were characterized by size exclusion chromatography on FPLC and native PAGE. Intersubunit hybrid hexamers containing five subunits of triple mutant and one subunit of C320S mutant were constructed by in vitro subunit hybridization followed by affinity chromatography. Kinetic analysis showed that a 5:1 hybrid hexamer, with only one C320S subunit able to bind NAD+ after DTNB modification, shows classical Michaelis-Menten kinetics with regard to NAD+. This contrasts with the apparent negative co-operativity shown by pure C320S hexamers and suggests that the interaction in NAD+ binding among subunits is eliminated in the hybrid. After removal of thionitrobenzoate, however, all of the subunits in the hybrid are able to bind NAD+. In this state the hybrid enzyme showed slight deviation from classical behavior with regard to NAD+, indicating reintroduction of some level of allosteric interaction. The hybrid hexamer also showed much reduced co-operativity with glutamate at pH 8.8, with a Hill coefficient of 3 for DTNB-treated hybrid (as compared to 5.2 for the pure C320S mutant) and 2.2 for the untreated hybrid. The fact that co-operativity in glutamate binding is not entirely eliminated correlates with evidence that the triple mutant subunits, though inactive toward glutamate, can nevertheless still bind this amino acid.
Magneto-optical imaging was used to visualize the inhomogeneous penetration of magnetic flux into polycrystalline TlBa2Ca2Cu3Ox films with high critical current densities, to reconstruct the local two-dimensional supercurrent flow patterns and to correlate inhomogeneities in this flow with the local crystallographic misorientation. The films have almost perfect c-axis alignment and considerable local a- and b-axis texture because the grains tend to form colonies with only slightly misaligned a and b axes. Current flows freely over these low-angle grain boundaries but is strongly reduced at intermittent colony boundaries of high misorientation. The local (<10-micrometer scale) critical current density Jc varies widely, being up to 10 times as great as the transport Jc (scale of approximately 1 millimeter), which itself varies by a factor of about 5 in different sections of the film. The combined experiments show that the magnitude of the transport Jc is largely determined by a few high-angle boundaries.
The effects of certain nutrients on dextransucrase (sucrose: 1,6-alpha-d-glucan 6-alpha-d-glucosyltransferase EC 2.4.1.5) production from Leuconostoc mesenteroides NRRL B-512F were studied. An increase in concentration of sucrose to 4% in the enzyme production medium resulted in the increase of activity of dextransucrase. Higher enzyme yields were obtained at low yeast extract and high phosphate concentrations. The presence of peptone and beef extract in the medium in addition to 2% yeast extract resulted in an enhanced production of dextransucrase. The enzyme activity increased by 30% by both peptone and beef extract. Addition of Tween 80 to the medium enhanced the production of enzyme and the activity was increased by 25%. Magnesium ions stimulated the activity marginally. Sodium fluoride enhanced the activity of dextransucrase by 25%.
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