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Biomedical subjects

K Muralidhar

Publications and source records attributed to K Muralidhar.

At least 37 records · Page 2Linked to original sources
PubMed1997

Heterogeneity in buffalo pituitary prolactin.

The Ellis procedure of serial extraction of gonadotropins and growth hormone (GH) followed by alkaline ethanol extraction was adopted to process freshly frozen buffalo pituitaries. The procedure after slight modification was found very useful as more than 2 mg of GH free immunoreactive prolactin (PRL) could be isolated from each gram of wet pituitary tissue. Further, the biochemical purity and immunobiological potency of the extracted PRL, designated as P-I, was comparable with that of the highly purified samples of homologous and heterologous PRLs. No non-PRL protein was detectable in P-I. Micro-heterogeneity with regard to size, charge, co- and post-translational modifications was also investigated under different conditions of extraction and at different stages of purification. Immunological and biological potencies were compared in homologous competitive enzyme linked immunosorbent assay (ELISA) developed for buffalo PRL and in rat Nb2 lymphoma proliferation assay respectively. Structural heterogeneity was observed in all the preparations checked including fresh pituitary homogenate and highly purified hormone. Nevertheless a 25 K species corresponding to the hormone monomer was always the only paramount form comprising more than 90% of the total PRL protein in all the samples including P-I. Similar size forms were observed in all preparations and were found to be equivalents of monomers, dimers, covalent-and non-covalent multimers, disulphide bridged forms and cleaved fragments. Other sibling species identified were glycosylated PRL, charge isoforms and forms that perhaps differed in their extractability from the pituitary tissue. Strong apparent size heterogeneity was displayed by the monomeric buffalo PRL. In light of these observations and the information on the structural and functional significance and the consequences of polymeric forms, the use of a heterogeneous PRL (P-I) as a reference hormone is recommended for a valid assay.

Animals↗
PubMed1997

A safe technique to monitor pulmonary artery pressure during and after paediatric cardiac surgery.

Pulmonary hypertensive crises (PHC) are a recognized cause of sudden clinical deterioration and death after the surgical correction of congenital heart disease. In this study, pulmonary artery pressure was monitored in 84 children (at high risk to develop PHC) aged nine days to five years (mean 1.4 years) using monitoring lines inserted percutaneously through the right internal jugular vein (IJV). Success rate of placement of the catheter tip in the pulmonary artery (PA) in the pre-incision period was not high (7%) but all catheter-tips were successfully placed in the PA by the surgeon before right atrial closure prior to separation from cardiopulmonary bypass. Complications related to the technique were transient ventricular/atrial arrhythmias (78.5%) during insertion and slipping or coiling (20%) of the catheter in the right ventricle. Complications relating to the IJV puncture included carotid arterial puncture and pneumothorax. No other complications were encountered. Monitoring lines inserted percutaneously and guided into the pulmonary artery during surgery provide a safe and practical way of monitoring pulmonary artery in infants and children at risk of postoperative pulmonary hypertensive crises.

Arrhythmias, Cardiac↗
PubMed1995

2-Mercaptopropionylglycine modulates the expression of c-jun and c-Ha-ras in regenerating rat liver.

Changes in the expression of two proto-oncogenes, c-jun and c-Ha-ras and their modulation by MPG were studied in regenerating rat liver. A significant increase in c-jun and c-Ha-ras mRNA levels was noted after partial hepatectomy. However, the increase in c-Ha-ras mRNA was much less when compared with c-jun mRNA levels. Metallothionein (MT-I) mRNA levels showed a gradual decrease following partial hepatectomy. However, the decrease in MT-I mRNA levels was not significant when intertime comparisons were made. MPG caused a significant reduction in the levels of c-jun and c-Ha-ras mRNA in the regenerating rat liver compared to untreated controls, but had very little effect on MT-I mRNA levels. Selective reduction in the expression of proto-oncogenes by MPG suggests that MPG may affect the cell proliferation by modulating the expression of these genes.

Animals↗
PubMed1995

A rapid method for the isolation of genomic DNA from Aspergillus fumigatus.

A majority of Aspergillus induced diseases are reported to be caused by Aspergillus fumigatus. In immunocompromized and post transplant cases it can lead to invasive aspergillosis. Due to this the molecular fingerprinting of aspergillus isolates by RFLP analysis and development of DNA diagnostic probes are gaining importance. Different methodologies are being adopted for extraction of the genomic DNA from fungus. The existing procedures for isolation of DNA are time consuming and range from several hours to few days. The most difficult step in the isolation of DNA from aspergillus species is to disrupt the tough chitin rich cell wall without causing damage to genomic DNA. We report here a rapid method for extraction of genomic DNA based on the cleavage of chitin with chitinase. The subsequent modification steps included are lysis and microwave treatment. The chromosomal DNA obtained by this procedure is 1.5-2.0 micrograms per mg of wet weight of mycelia and is observed to be minimally sheared. It is pure enough for restriction analysis and for use in the PCR to detect the gene coding for 18 kDa allergen which has been identified in our laboratory using western blot analysis with human patient sera.

Aspergillosis↗
PubMed1994

Mode of action of inhibin-like pineal antigonadotropin is different from melatonin during compensatory ovarian hypertrophy.

Both melatonin and pineal antigonadotropic peptides have the same end effect, i.e., prevention of the hypertrophic response when tested in the conventional compensatory ovarian hypertrophy (COH) model. The present work was undertaken to study the effect of melatonin and a melatonin- and steroid-free inhibin-like ovine pineal antigonadotropin (PI) on serum follicle stimulating hormone (FSH), luteinizing hormone (LH), and prolactin (PRL) following hemoiovariectomy in adult Holtzman rats and also to ascertain if any similarity exists in their mode of action during COH. While melatonin prevented the transient rise in FSH at 12 hr after unilateral ovariectomy (ULO), thus retaining the basal preoperative level, PI depressed basal levels of FSH too. In addition, melatonin suppressed PRL and LH levels at 12 hr and 120 hr after ULO, respectively. PI, on the other hand, had no effect on serum LH and PRL levels. In light of our earlier in vitro results, which showed a direct inhibitory effect of PI and not of melatonin on pituitary FSH synthesis and release, the present results indicate a dichotomy in the mode of action of PI and melatonin. PI acts directly at the level of the pituitary while melatonin may act at the level of the hypothalamus or higher brain centers to suppress the FSH surge and the ensuing compensatory response.

Animals↗
PubMed1994

Strategies for purification of four reproductive hormones from the same batch of buffalo (Bubalus bubalis) pituitaries.

The occurrence of different reproductive hormones like LH, FSH, TSH and prolactin, in different side fractions obtained during the extraction of buffalo pituitary glands either by the procedure of Papkoff et al. [Arch Biochem Biophys, 111 (1965) 431] or by that of Ellis [Endocrinology, 69 (1961) 554], was examined with the aid of antisera to respective heterologous hormones as well as bio-assays. Thus in the procedure of Papkoff et al., the SP-Sephadex fractions could be taken for purification of LH and TSH, while the acid pellet yielded prolactin. Further it was shown that 50% (NH4)2SO4 could be directly size fractionated and following cation exchange chromatography yields LH and TSH. FSH could be purified from 80% ammonium sulphate pellet. In another protocol of Ellis, differential extraction and chromatographic separation yielded all the four reproductive hormones. Some of the physico-chemical and immunobiological characteristics of these hormones are described.

Animals↗
PubMed1994

A possible urease-based homologous ELISA for buffalo prolactin.

The feasibility of a direct binding as well as competitive ELISA using urease labelled probe is described for buffalo pituitary prolactin. Rabbit anti-buPRL serum and goat anti-rabbit IgG conjugated to urease were used as primary and secondary antibodies respectively. Assay was performed in polystyrene wells pretreated with 3-amino-propyltriethoxysilane (APTES) compound. APTES pretreatment provided a more receptive surface for prolactin (PRL). In direct binding mode the assay could detect 24 pg of PRL per well. In competition mode the detection limit was less than 0.1 ng of competitor PRL per well. Urease-based ELISA was found highly sensitive when the substrate solution containing pH indicator, bromocresol purple, was used at lower pH (4-4.2). No false positive reactions occurred in the control wells. A good parallelism between buffalo serum sample inhibition curve and the standard PRL inhibition curve was observed.

Animals↗
PubMed1994

Bypass flow rates.

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Cardiopulmonary Bypass↗
PubMed1992

Attenuation of the cardiovascular responses to subcutaneous adrenaline in neurosurgical patients.

In 30 neurosurgical patients after induction of anaesthesia and random pretreatment with i.v. propranolol 1 mg or metoprolol 1 mg, heart rate and mean arterial pressure were measured at 30-s intervals after subcutaneous infiltration of adrenaline 1:200,000. While metoprolol prevented the cardiovascular effects of adrenaline infiltration, propranolol pretreatment was associated with a highly significant increase (P less than 0.01) in mean arterial pressure and a significant decrease (P less than 0.05) in heart rate. These results confirm the potentially serious interaction of propranolol and adrenaline during anaesthesia, and support the use of metoprolol instead, to obtund the cardiovascular effects of adrenaline infiltration.

Adult↗
PubMed1992

Heterogeneity in buffalo lutropin.

Lutropin (LH-1) from water buffaloes has been shown to exhibit microheterogeneity in the N-terminal amino-acid sequence of its alpha-subunit. The beta-subunit did not exhibit such microheterogeneity. Another protocol of purification yielded a preparation of buffalo LH (bu LH-2) different from the buffalo LH-1 in certain physico-chemical properties like ease of dissociation into subunits, sugar composition, isoelectric point, and elution profile on S-200. Data appear to indicate the presence of more than one form of buffalo lutropin.

Animals↗
PubMed1991

Physico-chemical and immunological characteristics of pituitary prolactin from water buffaloes (Bubalus bubalis).

Prolactin (PRL) was purified from freshly frozen pituitary glands of water buffaloes (Bubalus bubalis) by a combination of existing procedures of Ellis and Jiang and Wilhelmi involving serial extraction of different pituitary proteins. The partially purified preparation was further fractionated on DEAE-Sephadex followed by Sephadex G-100 chromatography. This was finally purified on HPLC. This preparation was found to be homogeneous by SDS-PAGE and HPLC and had a single N-terminus amino acid (Threonine). The molecular size was estimated to be 24K +/- 0.5 by SDS-PAGE and approximately 25K by GPC-HPLC. The buffalo PRL gave a dose dependent inhibition curve in a rat liver based radio receptor assay with a potency of 30-35 I.U./mg and also in a partial homologous RIA using 125I-buffalo PRL and rabbit anti-oPRL serum giving a potency of 30 I.U./mg. Metabolic labelling studies using 35SO4(2-) with buffalo pituitary minces showed the incorporation of radioactive sulfate into immunoprecipitable PRL-like material. Physico-chemical characterization of the site of the linkage between sulfate and PRL revealed the presence of Tyr-O-SO4 in bu-PRL. A high affinity monoclonal antibody (MAB) with Ka of 10(10) L/M, belonging to IgG1 isotype, and capable of cross reacting with ovine and bovine PRL was generated. This MAB was conformation specific as reduced and carboxymethylated PRL did not react with it. A homologous RIA system using this MAB has been standardised.

Animals↗