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Biomedical subjects

Satish Kumar

Publications and source records attributed to Satish Kumar.

At least 19 recordsLinked to original sources

Molecular characterization of coding sequences and analysis of Toll-like receptor 3 mRNA expression in water buffalo (Bubalus bubalis) and nilgai (Boselaphus tragocamelus).

Toll-like receptor 3 (TLR3), an antiviral innate immunity receptor recognizes double-stranded RNA, preferably of viral origin and induces type I interferon production, which causes maturation of phagocytes and subsequent release of chemical mediators from phagocytes against some viral infections. The present study has characterized TLR3 complementary DNA (cDNA) in buffalo (Bubalus bubalis) and nilgai (Boselaphus tragocamelus). TLR3 coding sequences of both buffalo and nilgai were amplified from cultured dendritic cell cDNA and cloned in pGEMT-easy vector for characterization by restriction endonucleases and nucleotide sequencing. Sequence analysis reveals that 2,715-bp-long TLR3 open reading frame encoding 904 amino acids in buffalo as well as nilgai is similar to that of cattle. Buffalo TLR3 has 98.6 and 97.9% identity at nucleotide level with nilgai and cattle, respectively. Likewise, buffalo TLR3 amino acids share 96.7% identity with cattle and 97.8% with nilgai. Non-synonymous substitutions exceeding synonymous substitutions indicate evolution of this receptor through positive selection among these three ruminant species. Buffalo and nilgai appear to have diverged from a common ancestor in phylogenetic analysis. Predicted protein structures of buffalo and nilgai TLR3 from deduced amino acid sequences indicate that the buffalo and nilgai TLR3 ectodomain may be more efficient in ligand binding than that of cattle. Furthermore, TLR3 messenger RNA expression in tissues as quantified by real-time PCR was found higher in nilgai than buffalo.

Amino Acid Sequence↗

Dynamics of thin liquid films on surfaces with a time-periodic wettability.

The dynamics of thin liquid films on surfaces whose wettability changes in a time-periodic manner are examined in this work. A nonlinear evolution equation based on the lubrication approximation is used to describe the film height, and attractions due to van der Waals forces are incorporated. Film wettability is varied through an imposed sinusoidal modulation of the Hamaker constant. A linear stability analysis predicts that if the mean Hamaker constant is negative, disturbances at the film surface will eventually decay regardless of the amplitude and frequency of the oscillation. However, numerical solution of the evolution equation shows that the film can rupture at a given frequency if the amplitude is sufficiently large. The associated characteristic wavelength can be predicted from results for constant-wettability surfaces if an appropriate effective Hamaker constant is used. For positive mean Hamaker constants, film rupture can be accelerated, delayed, or prevented depending on how the Hamaker constant changes early in the oscillation cycle. The effects of spatial gradients in wettability are also considered, and it is found that oscillation can delay but not prevent rupture. Inclusion of short-range repulsive forces leads to the formation of droplet-like structures separated by ultra-thin films, but this can be prevented by sufficiently large and slow oscillations of the Hamaker constant. The results of this work may find use in applications that make use of surfaces whose wettability can be controlled by external stimuli.

Journal Article↗

Identification of T-helper and linear B epitope in the hypervariable region of nucleocapsid protein of PPRV and its use in the development of specific antibodies to detect viral antigen.

Peste des petits ruminants is a highly contagious viral disease of small ruminants making its diagnosis difficult from the similar symptoms of Rinderpest. Computer based prediction algorithms was applied to identify antigenic determinants on the nucleocapsid (N) protein of PPRV. Specificity and antigenicity of each peptide was evaluated by solid phase ELISA. Six specific peptide sequences were evaluated in multiple antigenic peptide (MAP) form and immune response was evaluated by supplementing universal T-helper epitope human IL-1beta peptide (VQGEESNDK, amino acids 163-171). Out of the six peptides 19mer sequence corresponding to 454-472 region of N protein of PPRV was found to be highly immunogenic and specific to PPRV. Evaluation of overlapping peptides differing in length for this 452-472 region, showed minimum length of 14 amino acid residues were required for the stable affinity binding of antigen-antibody. The results of immunization and indirect ELISA indicated the presence of T-helper epitope at the N-terminal end and linear B epitope at the C-terminal region of 454-472 19mer of nucleocapsid peptide of PPRV-nucleocapsid protein. The antipeptide antibodies developed against this region showed specificity to PPRV antigen differentiating it from RPV when used in indirect ELISA and western blot analysis.

Amino Acid Sequence↗

kappa-casein-deficient mice fail to lactate.

Acquisition of milk production capabilities by an ancestor of mammals is at the root of mammalian evolution. Milk casein micelles are a primary source of amino acids and calcium phosphate to neonates. To understand the role of kappa-casein in lactation, we have created and characterized a null mouse strain (Csnk-/-) lacking this gene. The mutant kappa-casein allele did not affect the expression of other milk proteins in Csnk-/- females. However, these females did not suckle their pups and failed to lactate because of destabilization of the micelles in the lumina of the mammary gland. Thus, kappa-casein is essential for lactation and, consequently, for the successful completion of the process of reproduction in mammals. In view of the extreme structural conservation of the casein locus, as well as the phenotype of Csnk-/- females, we propose that the organization of a functional kappa-casein gene would have been one of the critical events in the evolution of mammals. Further, kappa-casein variants are known to affect the industrial properties of milk in dairy animals. Given the expenses and the time scale of such experiments in livestock species, it is desirable to model the intended genetic modifications in mice first. The mouse strain that we have created would be a useful model to study the effect of kappa-casein variants on the properties of milk and/or milk products.

Alleles↗

Slow aggregation of lysozyme in alkaline pH monitored in real time employing the fluorescence anisotropy of covalently labelled dansyl probe.

The onset of hen egg white lysozyme aggregation on exposure to alkaline pH of 12.2 and subsequent slow growth of soluble lysozyme aggregates (at 298 K) was directly monitored by steady-state and time-resolved fluorescence anisotropy of covalently attached dansyl probe over a period of 24 h. The rotational correlation time accounting for tumbling of lysozyme in solution (40 microM) increased from approximately 3.6 ns (in pH 7) to approximately 40ns on exposure to pH 12.2 over a period of 6 h and remained stable thereafter. The growth of aggregates was strongly concentration dependent, irreversible after 60 min and inhibited by the presence of 0.9 M l-arginine in the medium. The day old aggregates were resistant to denaturation by 6 M guanidine.HCl. Our results reveal slow segmental motion of the dansyl probe in day old aggregates in the absence of L-arginine (0.9 M), but a much faster motion in its presence, when growth of aggregates is halted.

Animals↗

A cocktail of affinity-purified antibodies reactive with diagnostically useful mycobacterial antigens ES-31, ES-43, and EST-6 for detecting the presence of Mycobacterium tuberculosis.

A cocktail of affinity-purified antibodies against diagnostically useful Mycobacterium tuberculosis H37Ra excretory-secretory protein antigens ES-31, ES-43, and EST-6 was explored for detection of circulating free and immune-complexed (IC) antigen in sera of patients with confirmed tuberculosis (TB) by sandwich enzyme-linked immunosorbent assay and compared with monospecific anti-ES-31 antibody. Out of 68 smear-positive TB cases studied, using cocktail antibody, a sensitivity of 97% (66/68) for immune-complexed cocktail antigen and 91% (62/68) for free cocktail-antigen detection was observed, compared to 91% (62/68) for immune-complexed ES-31 and 79% (54/68) for free ES-31 antigen when anti-ES-31 antibody was used alone. Thus, combinatorial use of antibodies showed improved sensitivity and was thus observed to be better than single antibody. The specificity was observed to be 99% for immune-complexed antigen using cocktail antibody. Furthermore, analysis of different groups of TB sera showed that circulating immune-complexed antigen is a sensitive marker than free antigen.

Antibodies, Bacterial↗

Instability of creeping flow past a deformable wall: the role of depth-dependent modulus.

Linear stability analysis is carried out to examine the effect of a depth-dependent modulus on the stability of creeping flow of a Newtonian fluid past an incompressible and impermeable linear elastic solid. Two different systems are considered: (i) Couette flow past a solid with a continuously varying modulus, and (ii) Couette flow past two adjacent solids with different thicknesses and moduli. For the first system, we find that between two configurations having the same average modulus, the more stable configuration is the one that has the higher modulus at the interface. In the case of two different configurations having the same interfacial modulus and the same average modulus, the more stable configuration is the one that has the higher modulus right below the interface. For the second system, we find that stability depends in a non-monotonic way on the modulus ratio (top modulus to bottom modulus) of the two solids. If the thickness of the top solid is less than a critical value, then increasing the modulus ratio initially causes the system to be less stable. Since this critical thickness decreases as the modulus ratio increases, increasing the modulus ratio beyond a certain point causes the system to be more stable. An analysis of the solid-solid interfacial boundary conditions suggests that the relationship between the stiffness of the top solid and the stability of the system is due to a jump in the base-state displacement gradient at the interface which creates a net perturbation displacement.

Journal Article↗

Numerical solution of ocular fluid dynamics in a rabbit eye: parametric effects.

Numerical calculations of the aqueous humor dynamics in the anterior chamber of a rabbit's eye are presented to delineate the basic flow mechanisms. The calculations are based on a geometrical model of the eye, which represents the Trabecular meshwork (TM) as a multilayered porous zone of specified pore sizes and void fraction. The outer surface of the cornea is assumed to be at a fixed temperature (corresponding to the ambient temperature), while the iris surface is assumed to be at the core body temperature. Results are obtained for both the horizontal upward-facing orientation of the eye, and the vertical orientation of the eye. Parameters varied include: the temperature difference between the iris and the cornea to underscore the important role of buoyancy in driving the aqueous humor flow; and, the pupil size reflecting different levels of ambient light. Buoyancy is observed to be the dominant driving mechanism for the convective motion in both orientations of the eye. Variations in the pupil size appear to have little influence on the IOP or flow distribution in view of the dominant role of buoyancy in controlling the flow motion. The study provides distributions of the shear stress and flow patterns and delineates the important role of the eye-orientation on these results.

Animals↗

Detection of antigen and antibody in childhood tuberculous meningitis.

OBJECTIVE: Mycobacterium tuberculosis excretory secretory 31 kDa, a serine protease antigen (M. tb ES-31), prepared from Mycobacterium tuberculosis H37Ra culture medium has been shown to have potential in detecting tuberculosis. Precise diagnosis and management of tuberculous meningitis, in children in particular, is essential to curtail mortality and morbidity. METHODS: In this study, M. tb ES-31 antigen, was used in Indirect ELISA to detect tuberculous IgG antibody, in sera and CSF samples while affinity purified anti ES-31 goat antibody was used in sandwich ELISA for detection of tuberculous antigen. In sixty-five samples each of CSF and sera from cases with neurotuberculosis and control with non-tuberculous diseases were collected from Kasturba Hospital, Sevagram. RESULTS: Among the 20 patients suffering from neurotuberculosis the IgG antibody was detected in 17(85%) of CSF and 16(80%) of sera samples, while antigen was detected in 18 (90%) in CSF and 16 (80%) in sera. Overall specificity of the assay for both IgG antibody and antigen detection in CSF was 96% while in sera it was 94% for IgG antibody and 96% for antigen detection. CONCLUSION: This study showed the usefulness of mycobacterial serine protease antigen and its antibody in detecting neurotuberculosis.

Antibodies, Bacterial↗

Oxidation studies on Andrographolide.

Jones oxidation of Andrographolide (1), gave mixture of three products (3-dehydroandrographolide (5), 3,19-bis dehydroandrographolide (6) and 19-dehydroandrographolide (7). Tritylation of andrographolide at C19-OH resulted to products 8 and diene 9, which can be converted to its acetate 10 and oxidation product 11.

Acetic Anhydrides↗

Deformity correction by external fixation and/or intramedullary nailing in hypophosphatemic rickets.

BACKGROUND: There are many modalities of treatment for complex lower extremity deformity in hypophosphatemic rickets. We evaluated the outcomes of deformity correction using an external fixation and/or intramedullary nailing in hypophosphatemic rickets. PATIENTS AND METHODS: 55 segmental deformities (20 femora, 35 tibiae) from 20 patients were examined retrospectively. There were 9 children and 11 adults. Distraction osteogenesis was used in 28 segments and acute deformity correction in 27. External fixation was applied in 24 segments, intramedullary nailing in 6, and external fixation and intramedullary nailing in 25. RESULTS: There were 18 major and 13 minor complications in 26 of 28 segments with distraction osteogenesis, and 13 major and 10 minor complications in 19 of 27 segments with acute correction. Recurrent deformity or refracture occurred in 10 of 21 segments with distraction osteogenesis by external fixation only, 4 of 6 with acute correction by intramedullary nailing, and 1 of 25 with distraction osteogenesis or acute correction by external fixation and intramedullary nailing. Nail-related complications occurred in 3 of 6 with intramedullary nailing and 2 of 25 with external fixation and intramedullary nailing. INTERPRETATION: External fixation and intramedullary nailing can be recommended to prevent complications during or after deformity correction in hypophosphatemic rickets.

Adolescent↗

Genetic variation and relationships among eight Indian riverine buffalo breeds.

Twenty-seven microsatellite loci were used to define genetic variation and relationships among eight Indian riverine buffalo breeds. The total number of alleles ranged from 166 in the Toda breed to 194 each in the Mehsana and the Murrah. Significant departures from the Hardy-Weinberg equilibrium were observed for 26 locus-breed combinations due to heterozygote deficiency. Breed differentiation was analysed by estimation of F(ST) index (values ranging from 0.75% to 6.00%) for various breed combinations. The neighbour-joining tree constructed from chord distances, multidimensional scaling (MDS) display of F(ST) values and Bayesian clustering approach consistently identified the Toda, Jaffarabadi, and Pandharpuri breeds as one lineage each, and the Bhadawari, Nagpuri, Surati, Mehsana and Murrah breeds as admixture. Analysis of molecular variance refuted the earlier classification of these breeds proposed on the basis of morphological and geographical parameters. The Toda buffaloes, reared by a tribe of the same name, represent an endangered breed from the Nilgiri hills in South India. Divergence time of the Toda buffaloes from the other main breeds, calculated from Nei's standard genetic distances based on genotyping data on seven breeds and 20 microsatellite loci, suggested separation of this breed approximately 1800-2700 years ago. The results of the present study will be useful for development of rational breeding and conservation strategies for Indian buffaloes.

Animals↗

Physical, X-ray diffraction and scanning electron microscopic studies of uroliths.

Identification of chemical constituents of calculus is important in the diagnosis and management of urolithiasis. The compositional variability of uroliths has different etiologies and requires various modes of treatment and prophylaxis. In the present study, we report the chemical compositional analyses of calculi recovered from buck and bullock by X-ray diffraction (XRD) and energy dispersive X-ray (EDX) techniques and ultra-structure examination by scanning electron microscopy (SEM). XRD and EDX investigations conclusively established the chemical compositions of urinary calculi under investigation. The calculus from buck (sample I) had calcium oxalate monohydrate, a dominant salt phase and magnesium compound in significant amount. The calculus from bullock (sample II) had magnesium ammonium phosphate phase, with significant amount of calcium in apatite form and K+ ions. SEM study at higher magnification (X 1000) showed bipyramidal crystals in external zones of urolith (sample I). The struvite apatite calculus showed that basic unit of structure was lamination and the laminitis appeared to be made up of fine granules and high porosity. The bio-mineralization process of calculus formation was also studied, with a view to take preventive and therapeutic measures for amelioration of urinary stone diseases in animals and humans.

Animals↗

IgG subclass antibody response to mycobacterial serine protease at different stages of pulmonary tuberculosis.

BACKGROUND: Tuberculosis (TB) is a chronic bacterial infection caused by M. Tuberculosis. Studies of antibody response in TB have focussed mainly on their usefulness as a diagnostic serological tool, with little attention given to analysis of antibodies at the isotype and subclass level in relation to disease pathogenesis. Hence the present study was done to analyse IgG subclass response at different stages of tuberculosis, in order to understand the immunological events associated with disease development. MATERIAL/METHODS: Sera samples were collected from 104 subjects: 79 tuberculosis patients (fresh, relapse and chronic cases) and 25 healthy normals. IgG subclass antibody response was analysed by indirect plate peroxidase ELISA against previously reported mycobacterial serine protease (ES-31) antigen. RESULTS: Fresh cases of tuberculosis showed increased IgG1 and IgG3 antibodies, while a few cases showed moderately increased IgG2. IgG1 and IgG3 were found to be elevated with increased bacillary load. Relapse and chronic cases showed increased IgG1 and IgG3, while positivity to IgG2 was decreased. Chronic cases showed a moderate increase in IgG4 antibody. Thus IgG1 and IgG3 were predominant in all forms of tuberculosis. CONCLUSIONS: The elevated levels of IgG1 and IgG3 antibodies to mycobacterial serine protease in active tuberculosis observed in this study provide an additional marker for diagnosis of tuberculosis. Furthermore, the higher level of these antibodies with high bacillary load patients and in chronic cases of tuberculosis may provide valuable insight into their possible role in disease progression.

Antibodies, Bacterial↗

Substituent effects on thermal decolorization rates of bisbenzospiropyrans.

[reaction: see text] A novel application of photochromic molecules is to mimic physiological oscillatory calcium signals by reversibly binding and releasing calcium ions in response to light. Substituent changes on the largely unexplored photochromic bisbenzospiropyran scaffold led to significant changes in thermal fading rates in several organic solvents. Excellent correlations have been found between fading rates and empirical Hammett constants as well as calculated ground-state energies. These correlations can be used to improve scaffold design.

Benzopyrans↗

Tamm-Horsfall protein acts as a general host-defense factor against bacterial cystitis.

AIMS: Tamm-Horsfall protein (THP) is urine's most abundant protein, but its biological function has remained elusive. Recently, THP-deficient (THP(-/-)) mice were shown to have difficulty clearing Escherichia coli from the urinary bladder. It has remained unclear if interaction between THP and E. coli is specific for E. coli or if THP has a versatile ability to clear a variety of bacteria from the bladder, and act as a broad host-defense mechanism against urinary tract infection (UTI). In this study, we examined the role of THP as a protective factor against UTI caused by bacteria other than E. coli, namely Klebsiella pneumoniae and Staphylococcus saprophyticus by determining if the THP(-/-) mouse has difficulty clearing these bacteria from its bladder. METHODS: THP gene knockout mice were generated by the technique of homologous recombination. K. pneumoniae and S. saprophyticus were introduced transurethrally, in separate experiments, into the bladders of the THP(-/-) and genetically similar wild-type (THP(+/+)) mice. Urine was collected at periodic intervals and cultured to quantitate the degree of bacteriuria. Bladders were surgically removed and examined histomorphometrically to determine the intensity of inflammation. RESULTS: Results showed that both with K. pneumoniae and with S. saprophyticus, the THP(-/-) mice had more severe bacteriuria in comparison with THP(+/+) mice. The inflammatory changes in the bladder were also markedly more intense in THP(-/-) mice with each of the bacterial species. CONCLUSIONS: These findings support the hypothesis that THP helps eliminate K. pneumoniae and S. saprophyticus from the urinary tract and acts as a general host-defense factor against UTI.

Adjuvants, Immunologic↗