Search PubMed⌕ Search

Biomedical subjects

A Sharma

Publications and source records attributed to A Sharma.

At least 235 records · Page 13Linked to original sources
PubMed2001

Optimisation of fermentation conditions for gluconic acid production by a mutant of Aspergillus niger.

Aspergillus niger ORS-4, isolated from the sugarcane industry waste materials was found to produce notable level of gluconic acid. From this strain, a mutant Aspergillus niger ORS-4.410 having remarkable increase in gluconic acid production was isolated and compared for fermentation properties. Among the various substrates used, glucose resulted into maximum production of gluconic acid (78.04 g/L). 12% concentration led to maximum production. Effect of spore age and inoculum level on fermentation indicated an inoculum level of 2% of the 4-7 days old spores were best suited for gluconic acid production. Maximum gluconate production could be achieved after 10-12 days of the fermentation at 30 degrees C and at a pH of 5.5. Kinetic analysis of production indicated that growth of the mutant was favoured during initial stages of the fermentation (4-8 days) and production increased during the subsequent 8-12 days of the fermentation. CaCO3 and varying concentrations of different nutrients affected the production of gluconic acid. Analysis of variance for the factors evaluated the significant difference in the production levels.

Aspergillus niger↗
PubMed2001

Effect of metal ions on growth of Pseudomonas aeruginosa and siderophore and protein production.

Pseudomonas aeruginosa (GRC1) isolated from potato rhizosphere, grew better on succinate medium than tryptic soy medium and produced hydroxamate type of siderophore in iron-deficient succinate medium. When the strain GRC1 was grown in the presence of different metal ion compounds, viz. ZnSO4, MnSO4, MnCl2 and FeCl3 at 6 and 12 microM concentrations individually, ZnSO4 (12 microM) promoted siderophore production but suppressed the growth and protein content of test organism. MnCl2 and FeCl3 (12 microM) enhanced the growth, whereas MnCl2 and MnSO4 (12 microM) induced protein contents of strain GRC1.

Bacterial Proteins↗
PubMed2001

Gluconic acid production by Aspergillus niger mutant ORS-4.410 in submerged and solid state surface fermentation.

Aspergillus niger ORS-4.410, a mutant of Aspergillus niger ORS-4 was produced by repeated irradiation with UV rays. Treatments with chemical mutagnes also resulted into mutant strains. The mutants differed from the parent strain morphologically and in gluconic acid production. The relationship between UV treatment dosage, conidial survival and frequency of mutation showed the maximum frequency of positive mutants (25%) was obtained along with a conidial survival of 59% after second stage of UV irradiation. Comparison of gluconic acid production of the parent and mutant ORS-4.410 strain showed a significant increase in gluconic acid production that was 87% higher than the wild type strain. ORS-4.410 strain when transferred every 15 days and monitored for gluconic acid levels for a total period of ten months appeared stable. Mutant ORS-4.410 at 12% substrate concentration resulted into significantly higher i.e. 85-87 and 94-97% yields of gluconic acid under submerged and solid state surface conditions respectively. Further increase in substrate concentration appeared inhibitory. Maximum yield of gluconic acid was obtained after 6 days under submerged condition and decreased on further cultivation. Solid state surface culture condition on the other hand resulted into higher yield after 12 days of cultivation and similar levels of yields continued thereafter.

Aspergillus niger↗
PubMed2001

Species specific chlamydiae antibodies in voluntary blood donors of Delhi.

BACKGROUND & OBJECTIVES: Different species of genus Chlamydia have been associated with ocular, genitourinary and respiratory infections, and coronary artery disease. Since the majority of these infections remain asymptomatic or subclinical, antibodies may be present in apparently healthy individuals, and the determination of species specific Chlamydia antibodies in a healthy population may reflect exposure. We therefore screened the sera of healthy blood donors for species specific Chlamydia antibodies by microimmunofluorescence assay. METHODS: Sera of 844 voluntary blood donors from Delhi were screened by microimmunofluorescence assay using specific antigens of C. trachomatis (18 serovars divided in 3 pools of serotypes A-C, D-K and L1-L3), C. psittaci and C. pneumoniae for Chlamydia antibodies. RESULTS: A total of 470 (55.69%) blood donors were found positive for Chlamydia antibodies. Of these, 361(42.77%) were positive for C. pneumoniae, 106 (12.5%) for C. trachomatis [of which 72 (8.5%) were against serotypes D-K and 34(4%) were against serotypes A-C]. There donors (0.3%) had antibodies to C. psittaci. INTERPRETATION & CONCLUSION: The results suggested that more than half of the study population (55.69%) is exposed to one or other species of chlamydiae. Majority of the donors (44.7%) had C. pneumoniae antibodies, suggesting the presence of widespread apparent or inapparent C. pneumoniae infection. The findings also suggest that Chlamydia antibody testing for the diagnosis of chlamydial infections may not be helpful due to the presence of antibodies in a large proportion of healthy individuals.

Antibodies, Bacterial↗
PubMed2001

Frontiers in cardiovascular health.

The XVII World Congress of the International Society for Heart Research, held in Winnipeg, Canada, July 6-11, 2001, was attended by more than 3,000 delegates from 55 countries. The gathering was a blend of clinical cardiologists, cardiothoracic surgeons and scientists working in experimental cardiology. The conference had an elaborate scientific program comprising 550 invited lectures divided into 82 symposia. Besides the lectures, there were about 600 poster presentations. The well-planned scientific program covered the areas of investigative, molecular and experimental cardiology as well as recent advances in clinical cardiology and cardiothoracic surgery.

Journal Article↗
PubMed2001

Frequency doubled Nd:YAG (532 nm) laser photocoagulation in corneal vascularisation: efficacy and time sequenced changes.

PURPOSE: To evaluate the efficacy of frequency-doubled Nd:YAG (532 nm) laser treatment in quiescent corneal vascularisation, and to record the sequential changes in lasered vessels and complications in eyes with one and two quadrant vascularisation. METHODS: Thirty eyes (30 patients)--15 eyes (15 patients) with one-quadrant and 15 eyes (15 patients) with two-quadrant corneal vascularisation were treated. Frequency-doubled Nd:YAG laser (532 nm) was used at laser setting of 120-480 mw power, 50-150 mm spot size and 0.05 sec pulse duration. The area of corneal vascularisation, status of treated corneal vessels, area of corneal opacity and visual acuity were recorded before treatment, at one week after treatment and thereafter at monthly intervals up to three months. RESULTS: The mean area of corneal vascularisation decreased from 20.09% to 8.31% of the total corneal area in group I (p<0.01) and from 44.34% to 20.67% of the total corneal area in group II (p<0.01) at 3 months' follow-up. The mean reduction in the area of corneal vascularisation was 58.64% in group I and 53.38% in group II (p>0.05). Of 148 corneal vessels treated, 60 (44.6%) were totally occluded, 44 (30%) partially occluded, 37 (28%) recanalized and there was one shunt vessel at one week following laser treatment. At three months' follow-up, 80 (54.15%) vessels were totally occluded, 14 (9%) partially occluded, 52 (35.14%) recanalised and two shunt vessels appeared. Thus, at three months' follow-up, the number of totally occluded vessels increased and partially occluded vessels decreased. Superficial corneal haemorrhage was observed in 4 (14%) patients. CONCLUSION: Frequency-doubled Nd:YAG (532 nm) laser photocoagulation appears a safe and effective means of reducing the area of corneal vascularisation in quiescent eyes with vascularised corneal opacities.

Adult↗
PubMed2000

Transformations in methane hydrates.

Detailed study of pure methane hydrate in a diamond cell with in situ optical, Raman, and x-ray microprobe techniques reveals two previously unknown structures, structure II and structure H, at high pressures. The structure II methane hydrate at 250 MPa has a cubic unit cell of a = 17.158(2) A and volume V = 5051.3(13) A(3); structure H at 600 MPa has a hexagonal unit cell of a = 11.980(2) A, c = 9.992(3) A, and V = 1241.9(5) A(3). The compositions of these two investigated phases are still not known. With the effects of pressure and the presence of other gases in the structure, the structure II phase is likely to dominate over the known structure I methane hydrate within deep hydrate-bearing sediments underlying continental margins.

Journal Article↗
PubMed2000

Meniscus instability in a thin elastic film

A new kind of meniscus instability leading to the formation of stationary fingers with a well-defined spacing has been observed in experiments with elastomeric films confined between a plane rigid glass and a thin curved glass plate. The wavelength of the instability increases linearly with the thickness of the confined film, but it is remarkably insensitive to the compliance and the energetics of the system. However, lateral amplitude (length) of the fingers depends on the compliance of the system and on the radius of curvature of the glass plate. A simple linear stability analysis is used to explain the underlying physics and the key observed features of the instability.

Journal Article↗
PubMed2000

Transgenic expression of cecropin B, an antibacterial peptide from Bombyx mori, confers enhanced resistance to bacterial leaf blight in rice.

The short persistence of cecropin B peptide in plants, due to post-translational degradation, is a serious impediment in its effective utilization for developing bacterial resistance transgenic plants. Two DNA constructs encoding the full-length precursor of cecropin B peptide and the mature sequence of cecropin B peptide preceded by a signal peptide derived from rice chitinase gene were transformed in rice. The differences in the transcriptional levels in independent transgenic lines showed moderate to high expression of cecropin B gene that correlated well with the differences in cecropin B accumulation observed by Western blot analysis. The development of lesions resulting from infection by Xanthomonas oryzae pv. oryzae was significantly confined in the infected leaflet of transgenic lines, when compared with the control plants.

Animals↗
PubMed2000

Knee position feedback: its effect on management of pelvic instability in a stroke patient.

PURPOSE: This is a case study of improvement in pelvic instability due to a stroke, with treatment. The patient had narrow knee-to-knee distance due to weakness in the pelvic muscles resulting in a narrow base of support. METHOD: Treatment was focused on pre-gait activities to improve upright posture control followed by gait training involving extrinsic auditory feedback about knee-to-knee distance. RESULTS: After two weeks of therapy with feedback technique incorporated in a functional context of gait therapy, the patient was able to advance his left lower extremity with proper foot placement. Laboratory measurements showed that step width and stride length gotten better after treatment as well. CONCLUSION: An inclusion of feedback information about knee-to-knee distance could benefit gait training of patients with pelvic instability.

Aged↗
PubMed2000

Possible mechanism of cardioprotective effect of angiotensin preconditioning in isolated rat heart.

The present study is designed to investigate the mechanism of cardioprotective effect of angiotensin II preconditioning. Isolated perfused rat heart was subjected to global ischaemia for 30 min followed by reperfusion for 120 min. Coronary effluent was analysed for lactate dehydrogenase and creatine kinase enzyme release to assess the degree of cardiac injury. Myocardial infarct size was estimated macroscopically using triphenyltetrazolium chloride staining. Four episodes of angiotensin II preconditioning markedly reduced lactate dehydrogenase and creatine kinase release in the coronary effluent and decreased myocardial infarct size. Administration of prazosin (alpha(1)-adrenoceptor antagonist) before global ischaemia reduced the extent of ischaemia-reperfusion-induced myocardial injury. Moreover, administration of prazosin during angiotensin II preconditioning or depletion of biogenic amines by reserpinisation (0.5 mg/kg i.p.) did not affect the cardioprotective effect of angiotensin II preconditioning. On the other hand, colchicine (5 mg/kg i.p.) or polymyxin B (50 microM) treatment markedly attenuated the cardioprotective effect of angiotensin II preconditioning. On the basis of these results, it may be concluded that the cardioprotective effects of angiotensin II preconditioning may be mediated through protein kinase C and may not involve release of norepinephrine or activation of alpha(1)-adrenoceptor.

Angiotensin II↗
PubMed2000

Primordial carbonylated iron-sulfur compounds and the synthesis of pyruvate.

Experiments exploring the potential catalytic role of iron sulfide at 250 degrees C and elevated pressures (50, 100, and 200 megapascals) revealed a facile, pressure-enhanced synthesis of organometallic phases formed through the reaction of alkyl thiols and carbon monoxide with iron sulfide. A suite of organometallic compounds were characterized with ultraviolet-visible and Raman spectroscopy. The natural synthesis of such compounds is anticipated in present-day and ancient environments wherever reduced hydrothermal fluids pass through iron sulfide-containing crust. Here, pyruvic acid was synthesized in the presence of such organometallic phases. These compounds could have provided the prebiotic Earth with critical biochemical functionality.

Carbon Monoxide↗
PubMed2000

Enhanced instability in thin liquid films by improved compatibility

We investigated experimentally the morphological evolution of thin polydimethylsiloxane films sandwiched between a silicon wafer and different bounding liquids with interfacial tensions varying by 2 orders of magnitude. It is shown that increasing the compatibility between film and bounding liquid by adding a few surfactant molecules results in a faster instability of shorter characteristic wavelength. Inversely, based on the characteristic parameters describing the instability we determined extremely small interfacial tensions with a remarkable accuracy.

Journal Article↗
PubMed2000

Class I MHC is stabilized against thermal denaturation by physiological concentrations of NaCl.

Class I MHC molecules are ternary complexes composed of an allotype specific heavy chain, a noncovalently associated protein beta(2)-microglobulin (beta(2)m), and a peptide. The complexes are assembled in the endoplasmic reticulum by a complex series of chaperones and peptide-loading mechanisms. In the absence of beta(2)m or peptide, very little class I heavy chain is transported to the surface of the cell. Complexes that do not contain all three parts of the protein are not made productively in vivo and not at all in vitro. The ability of the complex to withstand thermal denaturation in vitro has been shown to be related to the binding affinity of the peptide. Paradoxically, some low-affinity peptide complexes denature at or below human basal body temperatures in vitro but are effective biological agents in vivo. Here we show that these complexes are stabilized against thermal denaturation by physiological cosolvents and maximally stabilized by 150 mM NaCl. While the degree of stabilization by 150 mM NaCl is greatest for low-affinity peptide/MHC complexes, the mechanism of stabilization is independent of peptide sequence. This effect is hypothesized to occur by multiple mechanisms including increasing the affinity of beta(2)m for the complex and charge screening.

Amino Acid Sequence↗
PubMed2000

Role of nitric oxide in diabetes-induced attenuation of antinociceptive effect of morphine in mice.

The study was designed to investigate the role of nitric oxide (NO) in the diabetes-induced decrease of the antinociceptive effect of morphine. The nociceptive threshold in diabetic and non-diabetic mice was measured in the tail-flick test. Streptozotocin (200 mg/kg i.p.) was administered to induce experimental diabetes in the mice. Four weeks after the administration of streptozotocin, the tail-flick test was performed and urinary nitrite concentration was estimated using Greiss reagent. Experimental diabetes markedly decreased the antinociceptive effect of morphine (10 microg in 5 microl/mice i.c.v.) and significantly increased the urinary nitrite concentration. Administration of aminoguanidine (12 mg/mice) markedly improved the antinociceptive effect of morphine and attenuated the increase in urinary nitrite concentration in diabetic mice. It may be tentatively concluded that an increase in NO formation may be responsible for the observed decrease in antinociceptive effect of morphine in diabetic mice.

Analgesics, Opioid↗
PubMed2000

In vitro cultivation of human islets from expanded ductal tissue.

A major obstacle to successful islet transplantation for both type 1 and 2 diabetes is an inadequate supply of insulin-producing tissue. This need for transplantable human islets has stimulated efforts to expand existing pancreatic islets and/or grow new ones. To test the hypothesis that human adult duct tissue could be expanded and differentiated in vitro to form islet cells, digested pancreatic tissue that is normally discarded from eight human islet isolations was cultured under conditions that allowed expansion of the ductal cells as a monolayer whereupon the cells were overlaid with a thin layer of Matrigel. With this manipulation, the monolayer of epithelial cells formed three-dimensional structures of ductal cysts from which 50-to 150- micrometer diameter islet-like clusters of pancreatic endocrine cells budded. Over 3-4 weeks culture the insulin content per flask increased 10- to 15-fold as the DNA content increased up to 7-fold. The cultivated human islet buds were shown by immunofluorescence to consist of cytokeratin 19-positive duct cells and hormone-positive islet cells. Double staining of insulin and non-beta cell hormones in occasional cells indicated immature cells still in the process of differentiation. Insulin secretion studies were done over 24 h in culture. Compared with their basal secretion at 5 mM glucose, cysts/cultivated human islet buds exposed to stimulatory 20 mM glucose had a 2.3-fold increase in secreted insulin. Thus, duct tissue from human pancreas can be expanded in culture and then be directed to differentiate into glucose responsive islet tissue in vitro. This approach may provide a potential new source of pancreatic islet cells for transplantation.

Adult↗