Biomedical subjects

M K Sharma

Publications and source records attributed to M K Sharma.

At least 19 recordsLinked to original sources

PubMed2003

Anti-inflammatory activity of shikonin derivatives from Arnebia hispidissima.

Arnebia hispidissima ethanolic extract, after chromatography, yielded a number of shikonin derivatives, which were identified as arnebin-5, arnebin-6, teracryl shikonin, arnebinone and acetyl shikonin. All these compounds were firstly reported from this plant species and evaluated to the anti-inflammatory activity of ethanolic extract and isolated shikonin derivatives, models with carrageenan-induced paw edema and complete Freund's adjuvant (CFA)-induced chronic arthritis in rats were conducted. The observed results indicated that pre-treatment with arnebinone significantly inhibited the carrageenan-induced paw edema and also suppressed the development of chronic arthritis induced by CFA.

Animals↗

PubMed2002

Estrogen receptor, calcium mobilization and rat sperm motility.

Oral treatment with 0.4 mg/kg/day of tamoxifen citrate, an antiestrogen, has been reported to reduce the fertility of adult male rat, presumably through estrogen receptors expressed throughout the male reproductive tract. During the course of these studies, tamoxifen was observed to gradually alter the pattern of sperm motility in the cauda epididymides without reducing sperm counts. Studies were carried out to understand the mechanism involved in tamoxifen induced change in the sperm motility pattern. In order to study the direct effects of tamoxifen on motility, biochemical levels/activities of sperm calcium, cAMP, phosphodiesterase and dynein ATPase, normally implicated in sperm motility were studied In view of the fact that tamoxifen is a ligand of estrogen receptor, estrogen receptor alpha protein and transcript were localized on rat sperm membrane and the effect of tamoxifen studied. The present study demonstrated presence of estrogen receptor protein and mRNA in the rat sperm by immunofluorescence, western blotting and in situ hybridization respectively. Specificity of sperm estrogen receptors was confirmed by conventional binding studies using [3H]-estradiol. There was no effect of tamoxifen treatment on estrogen receptors in rat sperms. Biochemical analysis of the sperms from tamoxifen treated cauda epididymides revealed a significant increase in the levels of calcium and cAMP. A significant reduction was also apparent in the activity of dynein ATPase. Tamoxifen treatment did not alter phosphodiesterase activity. Estrogen receptors could be identified both in the control as well as tamoxifen treated rat sperms. It was concluded that tamoxifen treatment mobilized calcium from the intra- or extra-cellular pools with a concomitant increase in cAMP and presumably activation of PKA (protein kinase A). Tamoxifen altered the pattern of sperm motility through a calcium induced block in the activity of dynein ATPase, presumably through the activation of sperm phosphatase. The putative estrogen receptor mediated signal transduction pathway appears to be directly affected in the tamoxifen treated, sub-motile rat sperm.

Animals↗

PubMed2002

Anti-inflammatory and antimicrobial activities of triterpenoids from Strobilanthes callosus nees.

The anti-inflammatory and antimicrobial activities of the 95% ethanol extract, benzene fraction and isolated triterpenoids of Strobilanthes callosus were investigated. In the carrageenan-induced paw edema inflammation model, the taraxerol showed a high reduction of edema, but the antimicrobial effect observed was lower at the two doses employed. These results confirm the use of this plant in folk medicine as an anti-inflammatory and antimicrobial herbal drug.

Acanthaceae↗

PubMed2001

Effect of anxiolytics on blood sugar level in rabbits.

Anxiety disorders are more prevalent not only in normal individuals but also in diabetes mellitus. Diazepam, a benzodiazepine, and buspirone, an azaspirodecanedione, are the most often prescribed anxiolytics. Present study was aimed to investigate the effect of diazepam and buspirone on the blood sugar levels in rabbits. Buspirone (0.5 mg/kg/day p.o.) and diazepam (0.6 mg/kg/day p.o.) did not affect the glucose levels in rabbits even after one month of treatment. Present findings suggest that these two anxiolytics have minimal effect on blood sugar control.

Animals↗

PubMed2001

Activity of glutathione related enzymes and ovarian steroid hormones in different sizes of follicles from goat and sheep ovary of different reproductive stages.

The investigations on enzymes related to glutathione like glutathione-S-transferase (GST) and glutathione peroxidase (GSH-Px) have been carried out mostly in human and rat ovaries, however the studies on these enzymes in ruminants are relatively absent. In the present study the changes in the activity of these enzymes, in different sizes of follicles from goat and sheep ovaries of different reproductive stages, were investigated. The results demonstrated that the activity of the enzyme GST increased with the increase in size of the follicles from small to large follicles of follicular phase ovary and from small to medium follicles of luteal phase ovary in both the species, thereafter it decreased in large follicles of luteal phase ovary. There was increasing pattern in the activity of GSH-Px in the follicular phase follicles and a decreasing pattern in the luteal phase follicles from both the species. Thus the changes in the activity of glutathione related enzymes namely GST and GSH-Px in different size follicles from both the species during different reproductive phases are evident from the results. It is reasonable, therefore, to assume that these enzymes may have functional role in the steroid hormone metabolism in ruminant ovary as reported in human ovary.

Animals↗

PubMed2000

cDNA sequence and tissue-specific expression of a basic liver-type fatty acid binding protein in adult zebrafish (Danio rerio).

We have determined the nucleotide sequence for a cDNA clone derived from zebrafish (Danio rerio) that codes for a fatty acid binding protein (FABP). Amino acid sequence similarity of the zebrafish FABP was highest to FABPs isolated from the livers of catfish, chicken, salamander and iguana. The open-reading frame of the zebrafish FABP cDNA codes for a protein of 14.0 kDa with a calculated isoelectric point of 8.8. The zebrafish liver-type FABP (L-FABP) cDNA hybridized to single restriction fragments of total zebrafish genomic DNA digested with the restriction endonucleases HaeIII or EcoRI suggesting that a single copy of the L-FABP gene is present in the zebrafish genome. Northern blot analysis demonstrated that the zebrafish L-FABP cDNA hybridized to a transcript of 700 nucleotides in total zebrafish RNA. In situ hybridization and emulsion autoradiography revealed that the L-FABP was expressed exclusively in the liver of the adult zebrafish. Based on amino acid sequence similarity, the isoelectric point and its tissue-specific pattern of expression, we conclude that this zebrafish FABP belongs to the basic liver-type FABPs only found, thus far, in non-mammalian vertebrates.

Amino Acid Sequence↗

PubMed2000

Rec effect of certain textile dyes in Bacillus subtilis.

A large number of compounds are toxic, genotoxic, mutagenic, teratogenic and/or carcinogenic. The genotoxicity of four textile dyes commonly used in India namely Sulphur Red Brown 360 (SRB), Jade Green 2G (JG), Reactofix Turquoise Blue 5GFL (RTB) and Direct Scarlet 4BS (DS) was determined by Bacillus subtilis spore Rec assay, both in the presence and absence of metabolizing activation mixture (S9 mix). Each dye was toxic at higher dose levels. A dose-dependent increase in the depth of growth inhibition zones was observed for all dyes. Zones of inhibition were usually clearer at higher doses of the dyes and with Rec- bacteria, but were translucent with Rec+ bacteria. SRB and DS were toxic to Rec+ and Rec- bacteria. JG was less genotoxic in the absence of S9 mix, however, its genotoxic potential increased in the presence of S9 mix. Reactofix T blue was more genotoxic in the absence of S9 mixture.

Animals↗

PubMed1999

Biochemical and hormonal characterization of follicles from follicular and luteal phase ovaries of goat and sheep.

Follicles from goat and sheep ovaries were characterized for their biochemical and hormonal parameters to investigate the effect of developmental stage of follicles on ovarian steroidogenesis. The follicles were isolated mechanically from follicular and luteal phase ovaries and divided in 6 morphologically different groups (small, medium and large follicular and small, medium and large luteal). Follicles were characterized for their contents of protein, DNA, estradiol-17 beta and progesterone and the activity of 3 beta-hydroxysteroid dehydrogenase. There was a progressive increase in the contents of all these biomolecules and activity of the enzyme as size of follicles increased in both the follicular and luteal phase ovaries. Follicles from follicular phase ovaries exhibited higher estradiol-17 beta content than those shown by luteal phase follicles. The reverse pattern was obtained for progesterone content. The results provide the basic data on biochemical and hormonal entities at different stages of follicular development in small ruminants which may be useful for in vitro studies on regulation of follicular development and steroidogenesis.

Animals↗

PubMed1998

Vitreous loss during conversion from conventional extracapsular cataract extraction to phacoemulsification.

PURPOSE: To study the outcome of vitreous loss among senior surgeons converting from conventional extracapsular cataract extraction (ECCE) to phacoemulsification. SETTING: A university teaching hospital in the United Kingdom. METHODS: A retrospective analysis of 87 planned cataract extractions performed from January 1992 to December 1996 and complicated by vitreous loss was done. Outcome measures included postoperative complication rates and visual acuity. RESULTS: During the study, vitreous loss occurred in 39 patients having ECCE and in 48 having phacoemulsification; the latter group included 8 patients with dropped nucleus. Postoperative complications included cystoid macular edema (18.7% of phaco patients, 30.8% of ECCE patients), retinal detachment (2.1% of phaco patients, 5.1% of ECCE patients), and expulsive hemorrhage (5.1% of ECCE patients). Phaco patients had higher rates of postoperative corneal edema (27.1%) than ECCE patients (12.8%) and transient intraocular pressure elevation (33.3%) versus 20.5%) but were more likely to receive posterior chamber intraocular lenses (70.8% versus 35.9%; P = .0024, chi-square test). After excluding pre-existing diseases, 83.3% of phaco patients and 67.6% of ECCE patients achieved a visual acuity of 6/12 or better. CONCLUSIONS: With careful patient selection, experienced extracapsular surgeons converting to phacoemulsification can achieve favorable results even in the presence of complications such as vitreous loss or dropped nucleus.

Aged↗

PubMed1998

Corneoscleral burn during phacoemulsification surgery.

We report a case in which a severe corneoscleral burn occurred during phacoemulsification surgery. The equipment-tuning process was uneventful and routine surgery was expected. Severe tissue injury occurred because the anterior chamber collapsed momentarily and the phaco tip touched corneoscleral tissue. We discuss mechanisms by which this type of injury may occur and the likely cause in our case. We also suggest methods to reduce the incidence.

Aged↗

PubMed1998

Changes in superoxide dismutase activity and estradiol-17 beta content in follicles of different sizes from ruminants.

Subcellular distribution of oxygen free radical scavenging enzymes has recently been demonstrated in goat ovary. In the present study the follicles of the follicular phase were isolated mechanically from goat and sheep ovaries and grouped as small (< 3 mm), medium (3-6 mm) and large (> 6 mm) follicles. The specific (units/mg protein) and total (units/g tissue) activity of superoxide dismutase (SOD) was estimated in homogenate of different sizes of follicles. The small follicles of both the species contained highest specific and total activity (6.99 +/- 1.49, 107.9 +/- 3.1 in sheep and 3.57 +/- 0.09, 76.5 +/- 4.0 in goat, respectively), whereas large follicles showed lowest specific and total activity (32.02 +/- 0.25, 80.4 +/- 5.5 in sheep and 1.71 +/- 0.06, 63.20 +/- 2.20 in goat, respectively). The estradiol-17 beta was also estimated and expressed as ng/follicle. The results show that estradiol-17 beta content was highest in large follicle (8.00 +/- 0.46 in sheep and 4.5 +/- 0.73 in goat). The content of estradiol-17 beta was increased progessively as the size of the follicles increased. From these findings, an inverse relationship was observed between SOD activity and estradiol-17 beta content in the follicles of different sizes from ruminants which may have functional role in follicle development and steroidogenesis.

Animals↗

PubMed1996

Prolonged coronary artery occlusion-reperfusion sequences reduce myocardial free radical production: an electron paramagnetic resonance study.

Our purpose was to determine whether prolonged myocardial ischemia attenuates free radical production after early reperfusion. Twenty-two mongrel dogs underwent left anterior descending coronary artery occlusion for 20, 40, or 60 minutes followed by 30 minutes of reperfusion. Electron paramagnetic resonance spectroscopy was used to measure ascorbate free radical in the coronary vein effluent. Ascorbate free radical production during reperfusion was significantly (p < 0.05) reduced in the dogs undergoing 60 minutes of coronary artery occlusion compared with the dogs undergoing 40 and 20 minutes of occlusion. We conclude that prolonged myocardial ischemia results in less free radical production on reperfusion than do shorter periods of ischemia followed by reperfusion.

Animals↗

PubMed1994

Ascorbyl free radical as a real-time marker of free radical generation in briefly ischemic and reperfused hearts. An electron paramagnetic resonance study.

The role of free radicals in myocardial reperfusion injury remains controversial. We have developed a new method using ascorbyl free radical (AFR) as a real-time, quantitative marker of free radical generation during myocardial reperfusion. A total of 35 dogs were studied. Twelve open-chest dogs underwent either 5 minutes (n = 5) or 20 minutes (n = 7) of coronary artery occlusion and 30 minutes of reperfusion. Seven additional animals undergoing 20 minutes of coronary occlusion also received the antioxidant enzymes superoxide dismutase and catalase, beginning 10 minutes before occlusion through the end of reperfusion. Exogenous ascorbate was infused intravenously, and the concentration of AFR in the great cardiac vein was continuously measured by electron paramagnetic resonance spectroscopy. Preocclusion AFR concentration was similar in the three groups. Upon reperfusion, AFR rose significantly in each animal group (P < .05). However, the AFR rise in the 20-minute-occlusion group, 38 +/- 17%, was significantly greater than in the 5-minute-occlusion group, 27 +/- 14% (P < .002). In addition, in the animals that received superoxide dismutase and catalase, the rise in the AFR was markedly attenuated, 13 +/- 6% (P < .002). Two dogs that received ascorbate but did not undergo coronary artery occlusion/reperfusion sequences showed no change in coronary venous AFR signal, indicating the stability of the signal over time. Five dogs received ascorbate while undergoing interventions to alter coronary venous flow: intravenous saline, dobutamine, dipyridamole, and nitroglycerin. Coronary venous AFR changes were minimal despite large coronary flow alterations, indicating that the AFR signal is independent of changes in coronary venous flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Cardiac geometry and mass changes associated with pacing-induced cardiomyopathy in the dog.

We evaluated the effects of chronic rapid pacing (240 beats/min) on ventricular geometry and function and on cardiac mass in a canine model. Forty dogs were studied by two-dimensional echocardiography before and after 45 days of pacing. Compared with sham-operated control animals, the paced animals had significant increases in end-diastolic and end-systolic volume and a decrease in ejection fraction. The increase in ventricular volume was primarily the result of dilation of the short axis of the ventricular lumen, without significant changes in the long-axis dimension. Paced animals had biatrial hypertrophy but no change in ventricular or total cardiac mass.

Animals↗

PubMed1993

Comparative measures of systolic ejection during treadmill exercise by impedance cardiography and Doppler echocardiography.

Measurements of systolic ejection dynamics by impedance cardiography were compared with simultaneous Doppler echocardiography in normal subjects and coronary artery disease patients. Patients with chest pain admitted for elective coronary angiography were monitored by simultaneous impedance cardiography and Doppler echocardiography before, during, and after treadmill exercise. Ensemble-averaged ECG, impedance cardiogram (ICG), the first derivative of ICG (dZ/dt), and Doppler waveforms were analyzed to identify systolic ejection variables. The timing of aortic valve opening was well correlated (r = 0.78) the timing of peak ejection velocity was very well correlated (r = 0.86), and the timing of aortic valve closure was moderately correlated (r = 0.69 and r = 0.73) in these subjects. The thoracic electrical impedance acceleration and normalized impedance acceleration indices were moderately correlated with Doppler model acceleration (r = 0.74, r = 0.79). The impedance cardiogram waveforms are of complex origin and are related to both aortic blood velocity and aortic blood acceleration. Users of dZ/dt timing features for determining aortic valvular events might consider alternative impedance features to improve ejection time accuracy.

Adult↗

PubMed1993

Interaction of vitamin C and vitamin E during free radical stress in plasma: an ESR study.

To study the interaction of the antioxidant vitamins C and E in a biological system, we used electron spin resonance (ESR) spectroscopy to make serial measurements of ascorbate and tocopheroxyl free radicals in plasma subjected to continuous free radical-mediated oxidative stress. Upon initiation of a continuous oxidative stress, we observed an immediate increase in the concentration of ascorbate radical, which reached a peak, and then steadily declined. Only after the virtual disappearance of the ascorbate radical did we observe the appearance of the tocopheroxyl radical. These data are consistent with the hypothesis that ascorbate is the terminal small-molecule antioxidant in biological systems. This is the first experimental demonstration that the predicted thermodynamic hierarchy of ascorbate, alpha-tocopherol, and their free radicals holds in a biological system containing endogenous levels of these antioxidant vitamins.

Antioxidants↗

PubMed1993

The syringe nitroxide free radical--Part II.

Some plastic syringes introduce a nitroxide free radical into the fluids they contain. The EPR spectrum shows a triplet with aN = 17.0 +/- 0.1 G in plasma. We report here that this nitroxide/hydroxylamine couple serves as an antioxidant system, whose redox potential appears to be between that of vitamin C and vitamin E. This adventitious antioxidant can alter the course of free radical processes.

Ascorbic Acid↗

PubMed1992

Modulation of pituitary gonadotropins and prolactin secretion by testosterone in vitro.

Investigations were undertaken to study the differential modulation of LH, FSH and PRL secretion by testosterone (T) using whole pituitary (PI) or pituitary-hypothalamus coincubates (PHC) as in vitro constructs. PI and PHC from intact and castrated rats were incubated with or without T thrice, for 24 h each, (24 h x 3, total incubation period 72 h). The spent media was replenished every 24 h. At the end of 72 h, a few of the pituitary glands were challenged with 10 nM LHRH for 4 h. The spent media and pituitary glands were analyzed for LH, FSH and PRL using specific RIAs. Incubation of PI or PHC from intact rats with T stimulated the release of LH and FSH but inhibited the release of PRL. T had no effect on the intrapituitary contents of LH but inhibited intrapituitary contents of FSH and PRL, as compared to controls incubated without T. Castration increased intrapituitary contents of LH and FSH with concomitant decrease in PRL levels. Incubation of PI or PHC from castrated rats with T inhibited intrapituitary contents of LH to intact pituitary levels, while PRL levels were further reduced instead of being ameliorated. It is concluded that PI or PHC can be used as convenient in vitro models to monitor the effect of castration or of T modulation of pituitary and hypothalamus functions. T does not affect the synthesis of LH at the gonadotroph level but facilitates the regulation of intracellular LH and FSH levels. It is postulated that T inhibits the synthesis of FSH/PRL at the gonadotroph/lactotroph levels.

Animals↗