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Biomedical subjects

R K Sharma

Publications and source records attributed to R K Sharma.

At least 73 records · Page 4Linked to original sources
PubMed2002

Post-irrigation impact of domestic sewage effluent on composition of soils, crops and ground water--a case study.

Long-term irrigation with sewage water adds large amounts of carbon, major and micro- nutrients to the soil. We compared the spatial distribution of N, P, K and other micronutrients and toxic elements in the top 0.6 m of an alluvial soil along with their associated effects on the composition of crops and ground waters after about three decades of irrigation with domestic sewage effluent as a function of distance from the disposal point. Use of sewage for irrigation in various proportions improved the organic matter to 1.24-1.78% and fertility status of soils especially down to a distance of 1 km along the disposal channel. Build up in total N was up to 2908 kg ha(-1), available P (58 kg ha(-1)), total P (2115 kg ha(-1)), available K (305 kg ha(-1)) and total K (4712 kg ha(-1)) in surface 0.15 m soil. Vertical distribution of these parameters also varied, with most accumulations occurring in surface 0.3 m. Traces of NO3-N (up to 2.8 mg l(-1)), Pb (up to 0.35 mg l(-1)) and Mn (up to 0.23 mg l(-1)) could also be observed in well waters near the disposal point thus indicating initiation of ground water contamination. However, the contents of heavy metals in crops sampled from the area were below the permissible critical levels. Though the study confirms that the domestic sewage can effectively increase water resource for irrigation but there is a need for continuous monitoring of the concentrations of potentially toxic elements in soil, plants and ground water.

Agriculture↗
PubMed2002

Bioconversion of eucalyptus bark waste into soil conditioner.

An optimized protocol for the bioconversion of eucalyptus bark was devised. It comprised: (i) mechanical reduction in bark size to 0.5-3.0 cm, (ii) moistening to 60-65%, (iii) fortification with ligninase-rich fungus Volvariella sp. (S-1) and 2% urea and (iv) maintenance of this composting mix under aerobic and ambient condition for 14-15 weeks. The resulting bark soil conditioner (BSC) was an easily crumbling, reddish brown biomass, with physico-chemical and microbial properties which would enrich soil fertility/productivity.

Bacteria↗
PubMed2002

Prediction of endometriosis with serum and peritoneal fluid markers: a prospective controlled trial.

BACKGROUND: The objective of this prospective controlled trial was to investigate the ability of a group of serum and peritoneal fluid (PF) markers to predict, non-surgically, endometriosis. METHODS AND RESULTS: Serum and PF samples were obtained from 130 women while undergoing laparoscopy for pain, infertility, tubal ligation or sterilization reversal. Concentrations of six cytokines [interleukin (IL)-1beta, IL-6, IL-8, IL-12, IL-13 and tumour necrosis factor (TNF)-alpha] were measured in serum and PF, and reactive oxygen species (ROS) in PF, and levels were compared among women who were allocated to groups according to their post-surgical diagnosis. Fifty-six patients were diagnosed with endometriosis, eight with idiopathic infertility, 27 underwent tubal ligation or reanastomosis (control group) and 39 were excluded due to bloody PF. Only serum IL-6 and PF TNF-alpha could be used to discriminate between patients with and without endometriosis with a high degree of sensitivity and specificity (P < 0.001). A threshold of 15 pg/ml PF TNF-alpha provided 100% sensitivity and 89% specificity (positive likelihood ratio of 9.1 and negative likelihood ratio of 0). A threshold of 2 pg/ml for serum IL-6 provided a sensitivity of 90% and specificity of 67% (positive likelihood ratio of 2.7 and negative likelihood ratio of 0.14). CONCLUSIONS: By measuring serum IL-6 and PF TNF-alpha, it was possible to discriminate between patients with endometriosis and those without. Before these markers can be used as a non-surgical diagnostic tool, these data should be verified in a larger study.

Adult↗
PubMed2002

Preparation and comparative evaluation of 99mTc-labeled 2-iminothiolane modified antibodies and CITC-DTPA immunoconjugates of anti-EGF-receptor antibodies.

The use of antibodies as targeting agents for the delivery of radioisotopes to tumors is a promising concept that has received widespread attention since the advent of monoclonal antibody (mAb) technology. The following studies are described in this article: the 99mTc-randiolabeling of 2-iminothiolane (2-IT) modified antibodies and 6-p-isothiocyanatobenzyl- diethylene-triamine penta-acetic acid (CITC-DTPA) immunoconjugates of anti-EGF-receptor antibodies murine ior egf/r3 and humanized h-R3; the analytical methods for quality control of the radiopharmaceutical such as instant thin layer chromatography-silica gel (ITLC-SG); the biological assessment of the radiolabeled molecule using flow cytometry analysis; in vitro stability studies with cysteine and DTPA challenge and the biodistribution studies in 4NMRI xenografted nude mice with U-87 human glioblastoma multiforme and MDA-MB-468 breast cancer cell lines. Labeling efficency of (96.48 +/- 0.70%) (98.42 +/- 0.38%), (94.8 +/- 1.25%) and (96.41 +/- 0.89%) was achieved for 99mTC-2-IT ior efg/r3, 99mTc-CITC-DTPA- ior egf/r3, 99mTc-CITC-DTPA- h-R3 and 99mTc-DIACIM h-R3, respectively. Radiocolloids were less than 2.0% in all cases. The biological activity measured by flow cytometry analysis using the MDA-MB-468 breast cancer cell line showed an immunoreactivity fraction greater than 85% in all concentrations of each immunoconjugate. Challenge studies demonstrated no evidence of transcomplexation of 99mTc to 1.0 mM DTPA for 2-IT modified antibody ior egf/r3 and CITC-DTPA immunoconjugates and only 8.7%, 4.9% and 5.0% of the 99mTc-radiolabeled was transcomplexed to 1.0 mM cysteine after 1 h incubation at 37 degrees C for 2-IT modified antibody ior egf/r3, CITC-DTPA ior egf/r3 and CITC-DTPA h-R3, respectively. Biodistribution studies with 2-IT modified antibodies and CITC-DTPA immunoconjugates indicated high tumor uptake in both cell lines with both immunoconjugates and no accumulation of the radiolabeled antibodies in normal organs.

Adenocarcinoma↗
PubMed2002

Bile flow response to repetitive heat stress in rats.

BACKGROUND & OBJECTIVES: Heat stress produces loss of absorptive surface area of the small intestine, including the ileum which is the site of bile acid absorption. This may cause diarrhoea on account of the possible bile acid malabsorption. To explore this possibility, the effect of high ambient temperature exposure on bile flow was studied in the warm acclimated albino rats. METHODS: Following heat exposure at 38 +/- 0.5 degrees C for 4 h/day, for up to 5 consecutive days, bile flow in the rats was measured gravimetrically under pentobarbital-induced anaesthesia, at steady rectal temperature (37 +/- 0.7 degrees C), and flow characteristics and rate were studied. RESULTS: The bile flow increased with the rise in rectal temperature (Tre) in an anaesthetized animal but, the relationship between the two was not linear; the flow nearly ceased if rectal temperature exceeded 43 degrees-44 degrees C. At steady, near normal, rectal temperature, bile flow showed fluctuations and, repetitive heat exposure led to a significant increase in bile flow. INTERPRETATION & CONCLUSION: Exposure to high ambient temperature modulates liver secretory function to enhance bile flow rate and increase bile acid absorptive load on the small intestine, whose absorptive function is known to be adversely affected in heat stress.

Animals↗
PubMed2001

Bcl-2 expression during the development and degeneration of RCS rat retinae.

In various hereditary retinal degenerations, including that in Royal College of Surgeons (RCS) rats, the photoreceptors ultimately die by apoptosis. Bcl-2 is one of the genes, which regulates apoptosis and is thought to promote survival of cells. This study has investigated the developmental expression of Bcl-2 in RCS rat, which is a well-studied animal model for hereditary retinal degeneration. An antibody against Bcl-2 was used for its immunohistochemical localization in dystrophic RCS rat retinae from postnatal (PN) days 4, 7, 13, 35, 45, 70, 202 and 14 months. Results were compared with Bcl-2 localization in congenic non-dystrophic rats from PN 4, 7, 13, 44, 202 and 14 months. Bcl-2 immunoreactivity in non-dystrophic retinae was already present in PN 4 retinae in the nerve fiber layer (presumably in the endfeet of immature Müller cells) and in the proximal parts of certain radially aligned neuroepithelial cells/immature Müller cell radial processes. With increasing age the immunoreactivity in relatively more mature Müller cell radial processes spread distally towards the outer retina and between PN 13 and 44 it reached the adult distribution. No cell bodies in the ganglion cell layer were found to be immunoreactive. Expression of Bcl-2 immunoreactivity in dystrophic RCS rat retinae closely resembled that of non-dystrophic retinae. No immunoreactivity was seen in photoreceptors or retinal pigment epithelium in dystrophic or non-dystrophic retinae. In conclusion, Bcl-2 expression is not altered, either in terms of its chronology or the cell type expressing it, during retinal degeneration in RCS rats.

Animals↗
PubMed2001

Phosphorylation of human N-myristoyltransferase by N-myristoylated SRC family tyrosine kinase members.

N-Myristoyltransferase (NMT) is an essential eukaryotic enzyme that catalyzes the cotranslational and/or posttranslational transfer of myristate to the amino terminal glycine residue of a number of important proteins especially the non-receptor tyrosine kinases whose activity is important for tumorigenesis. Human NMT was found to be phosphorylated by non-receptor tyrosine kinase family members of Lyn, Fyn and Lck and dephosphorylated by the Ca(2+)/calmodulin-dependent protein phosphatase, calcineurin. Deletion of 149 amino acids from the N-terminal end resulted in the absence of phosphorylation suggesting that the phosphorylation sites are located in the N-terminal end of NMT. Furthermore, a site-directed mutagenesis study indicated that substitution of tyrosine 100 with phenylalanine served NMT as a poor substrate for the Lyn kinase. A synthetic peptide corresponding to the amino-terminal region encompassing tyrosine 100 of NMT served as a good substrate for the Lyn and Fyn kinases. Our studies also indicated that NMT was found to interact with Lyn through its N-terminal end in a phosphorylation-dependent manner. This is the first study demonstrating the cross-talk between NMT and their myristoylated protein substrates in signaling pathways.

Acyltransferases↗
PubMed2001

A novel calcium-regulated membrane guanylate cyclase transduction system in the olfactory neuroepithelium.

This report defines the identity of a calcium-regulated membrane guanylate cyclase transduction system in the cilia of olfactory sensory neurons, which is the site of odorant transduction. The membrane fraction of the neuroepithelial layer of the rat exhibited Ca(2+)-dependent guanylate cyclase activity, which was eliminated by the addition of EGTA. This indicated that the cyclase did not represent a rod outer segment guanylate cyclase (ROS-GC), which is inhibited by free Ca(2+). This interpretation was supported by studies with the Ca(2+) binding proteins, GCAPs (guanylate cyclase activating proteins), which stimulate photoreceptor ROS-GC in the absence of Ca(2+). They did not stimulate the olfactory neuroepithelial membrane guanylate cyclase. The olfactory neuroepithelium contained a Ca(2+) binding protein, neurocalcin, which stimulated the cyclase in a Ca(2+)-dependent fashion. The cyclase was cloned from the neuroepithelium and was found to be identical in structure to that of the previously cloned cyclase termed GC-D. The cyclase was expressed in a heterologous cell system, and was reconstituted with its Ca(2+)-dependent activity in the presence of recombinant neurocalcin. The reconstituted cyclase mimicked the native enzyme. Immunocytochemical studies showed that the guanylate cyclase coexists with neurocalcin in the apical region of the cilia. Deletion analysis showed that the neurocalcin-regulated domain resides at the C-terminal region of the cyclase. The findings establish the biochemical, molecular, and functional identity of a novel Ca(2+)-dependent membrane guanylate cyclase transduction system in the cilia of the olfactory epithelium, suggesting a mechanism of the olfactory neuroepithelial guanylate cyclase regulation fundamentally distinct from the phototransduction-linked ROS-GC.

Animals↗
PubMed2001

Negatively calcium-modulated membrane guanylate cyclase signaling system in the rat olfactory bulb.

The mechanism by which the individual odor signals are translated into the perception of smell in the brain is unknown. The signal processing occurs in the olfactory system which has three major components: olfactory neuroepithelium, olfactory bulb, and olfactory cortex. The neuroepithelial layer is composed of ciliated sensory neurons interspersed among supportive cells. The sensory neurons are the sites of odor transduction, a process that converts the odor signal into an electrical signal. The electrical signal is subsequently received by the neurons of the olfactory bulb, which process the signal and then relay it to the olfactory cortex in the brain. Apart from information about certain biochemical steps of odor transduction, there is almost no knowledge about the means by which the olfactory bulb and cortical neurons process this information. Through biochemical, functional, and immunohistochemical approaches, this study shows the presence of a Ca(2+)-modulated membrane guanylate cyclase (mGC) transduction system in the bulb portion of the olfactory system. The mGC is ROS-GC1. This is coexpressed with its specific modulator, guanylate cyclase activating protein type 1 (GCAP1), in the mitral cells. Thus, a new facet of the Ca(2+)-modulated GCAP1--ROS-GC1 signaling system, which, until now, was believed to be unique to phototransduction, has been revealed. The findings suggest a novel role for this system in the polarization and depolarization phenomena of mitral cells and also contradict the existing belief that no mGC besides GC-D exists in the olfactory neurons.

Animals↗
PubMed2001

Radiotherapeutic response of Ehrlich ascites tumor cells perfused in agarose gel threads and implanted in mice. A 31P MR spectroscopy study.

AIM: In order to obtain better understanding of radiation-induced alterations in intracellular metabolism, a dynamic and non-invasive experimental model system is required. A serial study in cultured tumor cell line followed by verification in the in vivo samples may be of considerable value for non-invasive prediction and/or detection of tumor response to therapy. The present study was undertaken to evaluate the radiation response of perfused Ehrlich ascites tumors cells (EATC) immobilized in agarose gel matrix to that observed in mouse bearing EATC tumor, in order to identify biomarkers of radiation response. MATERIALS AND METHODS: Perfused EAT cells, entrapped in agarose gel threads were irradiated in the perfusion assembly outside the magnet with fast electrons (6 Gy, 1 Gy/min) using 30 MeV Betatron. Solid EATC tumors implanted subcutaneously onto right hand limb of Swiss-albino strain "A" mice, were focally irradiated using 60Co teletherapy (10 Gy, 0.4 Gy/min). Metabolites changes were monitored by 31P MR spectroscopic techniques. RESULTS: A post-irradiation decrease in the levels of ATP and ADP along with an increase in inorganic phosphate and glycerophosphocholine levels was observed. The ratios of beta-phosphate of ATP to inorganic phosphate (beta-ATP/Pi), and phosphocholine to glycerophosphocholine (PC/GPC), declined during 1-5 hours following irradiation, in perfused EAT cells and in the solid tumors implanted in mice. CONCLUSION: Perfused cells could be used as a simple model of tumor for prediction of clinical radiotherapeutic response. The present study demonstrates that radiation damage may be occurring both at the DNA protein as well as the membrane lipid levels. Therefore, the bioenergetics and phospholipid profiles of tumor cells could be used as complimentary, reliable and sensitive indirect indicators for devising predictive assays for assessment and monitoring of radiation response, which will also facilitate the individualization and optimization of tumor radiotherapy.

Adenosine Diphosphate↗
PubMed2001

Spectrum of adolescent-onset nephrotic syndrome in Indian children.

There are few data regarding adolescent-onset nephrotic syndrome (NS) and no guidelines for biopsy criteria and treatment protocol. This study was conducted to analyze the clinical spectrum of adolescent-onset NS and evaluate possible biopsy criteria in these children. A prospective analysis was carried out on all patients with idiopathic NS (fulfilling the ISKDC criteria) with onset between 1 and 18 years of age. They were evaluated clinically, followed by biochemical investigations and kidney biopsy. These characteristics of patients with onset between 1 and 12 years (group A) were compared with the same parameters in patients with onset between 12 and 18 years of age (group B) referred to our hospital over the same period. Among all clinical parameters, microhematuria was significantly more prevalent in adolescents (P<0.001). Kidney biopsy was performed in 88% of adolescent patients. Focal segmental glomerulosclerosis (FSGS) was the most-common histopathology in group B (46.3%) compared with minimal change disease (MCD) in group A (42.9%). Group B had a significantly higher frequency of membranoproliferative glomerulonephritis (MPGN) (P<0.005) and a significantly lower frequency of MCD (P<0.001). The biochemical parameters at the onset were similar. On comparing microhematuria, hypertension, and renal insufficiency at presentation, we observed that two or more of these features were present in all patients with MPGN and only in 19.6% of adolescents with MCD, mesangioproliferative glomerulonephritis, and FSGS. The frequency of steroid resistance was significantly higher in group B (P<0.001). In conclusion, adolescent-onset NS differs from the childhood variety in having a significantly higher frequency of hematuria, steroid resistance, and evidence of non-MCD, especially MPGN, on histopathology. Kidney biopsy can be restricted to those adolescents who have at least two abnormal clinical/biochemical features or are steroid non-responders.

Adolescent↗
PubMed2001

Prognostic significance of distal renal tubular acidosis in posterior urethral valve.

The prognostic significance of distal renal tubular acidosis (DRTA) in the development of overt nephropathy (ON) in children with posterior urethral valves (PUV) is not clear. This condition was studied prospectively in 22 children with posterior urethral valve (PUV), with normal renal function. Prior to surgery, the children with ON had a higher incidence of bilateral reflux (P=0.006), but the difference was not significant for age at surgery (P=0.31), duration of voiding symptoms prior to surgery (P=0.30), presence of DRTA (P=0.35) and bladder abnormalities (P=0.27), with none of these factors being significant on logistic regression analysis. At the end of the follow-up, after surgery, age at surgery (P < or = 0.0001), duration of voiding symptoms prior to surgery (P < or = 0.0003), persistent DRTA (P=0.0001) and persistent bladder dysfunction (P=0.02) after surgery were significantly higher in children with ON. On univariate logistic regression analysis, age at surgery (P=0.009), duration of voiding symptoms prior to surgery (P=0.01), persistent DRTA (P=0.002) and persistent bladder abnormalities (P=0.03) after surgery were significant for ON after surgery, but on stepwise multivariate logistic regression analysis only persistent DRTA (P=0.002) turned out to be significant. We conclude that persistent DRTA after surgery can predict overt nephropathy in children with PUV after surgery.

Acidosis, Renal Tubular↗
PubMed2001

DNA damage in patients with untreated cancer as measured by the sperm chromatin structure assay.

OBJECTIVE: To examine the relationship between sperm chromatin defects, evaluated by sperm chromatin structure assay (SCSA) and semen characteristics in cryopreserved semen specimens from patients diagnosed with various types of cancer. DESIGN: Prospective study. SETTING: Andrology laboratory at a tertiary care hospital. PATIENT(S): Cryopreserved semen samples from 12 healthy fertile men and 37 men diagnosed with cancer: testicular cancer (n = 20), Hodgkin's disease (n = 11), non-Hodgkin's disease (n = 4), and other neoplasm (n = 2). INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): The shift of green (native DNA) to red (denatured, single-stranded DNA) fluorescence in acridine orange-stained nuclei was measured and quantified using the expression alpha(t)(red fluorescence/[red + green fluorescence] per cell). Sperm DNA damage was correlated with classical semen characteristics. RESULT(S): Cancer patients as a group had significantly higher DNA damage when compared with controls. Specimens with high COMPalpha(t) values (percentage of sperm with denatured DNA) were present in all groups of cancer patients. No meaningful correlation was seen between the extent of DNA damage and classical semen measures. CONCLUSION(S): DNA damage in spermatozoa is prevalent in the majority of cancer patients. SCSA provides important information about the biochemical integrity of sperm DNA in men with cancer before their treatment.

Acridine Orange↗
PubMed2001

Creatine kinase as an indicator of sperm quality and maturity in men with oligospermia.

OBJECTIVES: To determine the differences among the creatine kinase (CK) levels in the spermatozoa of subfertile men with mild, moderate, or severe oligospermia and to examine the differences in CK activity between infertile patients with various clinical diagnoses and a group of normal healthy donors (control). CK is a marker of sperm maturity that correlates with the sperm fertilizing capacity. Elevated levels are associated with an increased rate of functional abnormalities and increased cytoplasmic retention. METHODS: We compared the CK levels in 51 oligospermic men who could not initiate a pregnancy. Patients were categorized according to their degree of oligospermia as defined by the total sperm count: mild (greater than 10 to 40 x 10(6); n = 30), moderate (5 to 10 x 10(6); n = 11), and severe (less than 5 x 10(6); n = 10). These patients were further classified according to their diagnosis (ie, varicocele, n = 24; unexplained infertility, n = 17; vasectomy reversal, n = 9; and unknown diagnosis, n = 1). A separate group consisting of 25 healthy donors was included as a control group. A computer-assisted semen analyzer assessed the sperm characteristics, and the CK levels were measured using a CK test kit after the enzyme was extracted with Triton-X. RESULTS: The CK levels were significantly higher in the sperm of the severely oligospermic group (8.8 +/- 6.5 IU/10(8) sperm) than in the moderate (0.50 +/- 0.19 IU/10(8) sperm) and mild (0.49 +/- 0.15 IU/10(8) sperm) groups (P <0.0001). The mean CK level in the severely oligospermic group was 18-fold higher than that in the moderate (P = 0.03) and mild (P <0.001) groups. The CK levels were significantly higher in all three infertile groups compared with the donor group (0.06 +/- 0.01 IU/10(8) sperm). Patients with varicocele had the highest CK level (3.42 +/- 2.56 IU/10(8) sperm) compared with patients in the vasectomy reversal group (1.73 +/- 0.98 IU/10(8) sperm) and the idiopathic infertility group (0.26 +/- 0.08 IU/10(8) sperm). CONCLUSIONS: Elevated CK levels are associated with severe oligospermia, irrespective of the clinical diagnosis. CK may be a sensitive indicator of sperm quality and maturity in the follow-up of patients treated for male factor infertility.

Creatine Kinase↗
PubMed2001

Evaluation of potential tracer ability of (99m)Tc-labeled acetylated LDL for scintigraphy of LDL-scavenger receptor sites of macrophageal origin.

Low-density lipoprotein (LDL) receptors are ubiquitously present in a variety of human tissues. Scavenger receptors, which are the activated macrophages bearing receptors for modified LDL, have been shown to be densely located at the atherosclerotic lesions. Acetylated LDL competes with oxidized LDL for access to these receptors. The present study was undertaken to optimize (99m)Tc labeling of two different forms of LDLs [i.e., native (Na) and acetylated (Ac)] and to explore their utility for the scintigraphy of densely localized scavenger LDL-receptor activity in vivo. Native and acetyl-LDL were labeled with (99m)Tc using sodium dithionite as a reducing agent. Significant hepatic and muscular uptake precluded optimal availability of (99m)Tc-Ac-LDL in blood, which favors macrophageal binding in sterile abscess models in rabbits. (99m)Tc-Ac-LDL behave as a novel tracer for imaging densely localized scavenger receptor sites constituted by activated macrophages at the site of independent inflammatory lesions and appears promising for the scintigraphy of atherosclerotic lesions.

Acetylation↗
PubMed2001

Three dimensional atomic model and experimental validation for the ATP-Regulated Module (ARM) of the atrial natriuretic factor receptor guanylate cyclase.

Atrial natriuretic factor (ANF) receptor guanylate cyclase (ANF-RGC) is a single chain transmembrane-spanning protein, containing both ANF binding and catalytic activities. ANF binding to the extracellular receptor domain activates the cytosolic catalytic domain, generating the second messenger cyclic GMP. Obligatory in this activation process is an intervening transduction step, which is regulated by the binding of ATP to the cyclase. The partial structural motif of the ATP binding domain of the cyclase has been elucidated and has been termed ATP Regulatory Module (ARM). The crystal structures of the tyrosine kinase domains of the human insulin receptor and haematopoietic cell kinase were used to derive a homology-based model of the ARM domain of ANF-RGC. The model identifies the precise configuration of the ATP-binding pocket in the ARM domain, accurately represents its ATP-dependent features, and shows that the ATP-dependent transduction phenomenon is a two-step mechanism. In the first step, ATP binds to its pocket and changes its configuration; in the second step, via an unknown protein kinase, it phosphorylates the cyclase for its full activation.

Adenosine Triphosphate↗