Biomedical subjects

S K Gautam

Publications and source records attributed to S K Gautam.

8 recordsLinked to original sources

PubMed2007

Isolation and characterization of embryonic stem cell-like cells from in vitro-produced buffalo (Bubalus bubalis) embryos.

This study was carried out to isolate and characterize buffalo embryonic stem (ES) cell-like cells from in vitro-produced embryos. Inner cell mass (ICM) cells were isolated either mechanically or by enzymatic digestion from 120 blastocysts whereas 28 morulae were used for the isolation of blastomeres mechanically. The ICM cells/ blastomeres were cultured on mitomycin-C-treated feeder layer. Primary cell colony formation was higher (P < 0.05) for hatched blastocysts (73.1%, 30/41) than that for early/expanded blastocysts (25.3%, 20/79). However, no primary cell colonies were formed when blastomeres obtained from morulae were cultured. Primary colonies were formed in 14.1% (12/85) of intact blastocyst culture, which was significantly lower (P < 0.05) than that of 41.6% for ICM culture. These colonies were separated by enzymatic or mechanical disaggregation. Using mechanical disaggregation method, the cells remained undifferentiated and two buffalo ES cell-like cell lines (bES1, bES2) continued to grow in culture up to eight passages. However, disassociation through enzymatic method resulted in differentiation. Undifferentiated cells exhibited stem cell morphological features, normal chromosomal morphology, and expressed specific markers such as alkaline phosphatase (AP) and Oct-4. Cells formed embryoid bodies (EBs) in suspension culture; extended culture of EBs resulted in formation of cystic EBs. Following prolonged in vitro culture, these cells differentiated into several types of cells including neuron-like and epithelium-like cells. Furthermore, the vitrified-thawed ES cell-like cells also exhibited typical stem cell characteristics. In conclusion, buffalo ES cell-like cells could be isolated from in vitro-produced blastocysts and maintained in vitro for prolonged periods of time.

Animals↗

PubMed2006

Dechlorination of DDT mediated by bimetallic systems.

DDT dechlorination efficiencies of bimetallic systems, namely, Mg0-Zn, Mg0-Ni, and Mg0-Co were compared. All the systems transformed DDT with efficiencies exceeding 98% within 24 h. Based on GC-ECD and GC-MS analyses a step-wise and sequential dechlorination of DDT by Mg0-Zn system in 1:1 water acetone phase via 1,1 dichloro, 2,2- bis (p-chlorophenyl) ethane (DDD), 1, chloro, 2,2 bis (p-chlorophenyl) ethane (DDMS) to 2,2 bis (p-chlorophenyl) ethane (DDNS) was noted. Accumulation of DDNS as the end product indicates that all three alkyl chlorine atoms of DDT were removed by Mg0-Zn system. Mg0-Co also showed almost complete removal of DDT in water-acetone phase that was accompanied by the accumulation of DDD followed by a decline in its concentration as a function of time. On the other hand, Mg0-Ni system exhibited inefficient removal of DDT in water-acetone phase. In pure acetone phase, Mg0-Co system and Mg0-Ni dechlorinated DDT with the accumulation of DDE and DDMU as end products following 24 h of reaction. The presence of surfactants or organic solvents is required to ensure solubilization of DDT. Also addition of acid is essential to provide sufficient protons for efficient reductive dechlorination via hydrogenation. Advantage of Mg0 based dehalogenation reactions is that they occur at high rates under ambient temperatures, and pressure and oxygen need not be excluded in the reaction phase. Our studies revealed that Mg0-Zn is the best option among all tested systems due to its high reactivity and low cost, and may be used to treat DDT contaminated water.

Catalysis↗

PubMed2003

Paediatric dentistry in the new millennium: 4. Cost-effective restorative techniques for primary molars.

In the fourth article in this series the techniques for carrying out pulp therapy and stainless steel restoration in primary molars are discussed. Early pulp involvement in primary molars means that pulp therapy and the use of appropriate coronal restoration, such as stainless steel crowns, are indispensable if repetitive restoration of primary molars is to be avoided. These techniques themselves are not difficult to carry out once the child's co-operation is established and should be well within the capability of any dentist with an interest in the dental care of children.

Cementation↗

PubMed1997

Cross-flow microfiltration of blood through an extracorporeal device: a study in parameterization.

This paper develops a new approach for the general description of membrane plasma separator performance by using dimensional analysis. Experiments involved cross-flow microfiltration of goats' blood across flatsheet polyvinylidene fluoride durapore membranes of pore size 0.65, 0.45 and 0.22 microns in a thin-channel device. Certain non-dimensional numbers are evolved which represent the grouping of relevant filtration parameters and which contribute to the global characterization of membrane-based plasmapheresis devices.

Hemodiafiltration↗

PubMed1995

Exploiting temperature dependence to improve selectivity in membrane-based plasmapheresis.

Temperature effects on cross-flow membrane plasmapheresis have been investigated with the help of hydrophillic polyvinylidene fluoride (PVDF) Durapore membranes of pore size 0.65 micron and an effective filtration area 30 cm2, using a thin-channel device (Minitan-S, Millipore Inc., U.S.A.) and goat's blood as the working fluid. The filtration and sieving properties have been characterized by evaluating normal saline (0.9 g%) flux and the sieving coefficients of albumin, immunoglobulins, and fibrinogen respectively. Runs were performed at 10 +/- 1, 20 +/- 1, 30 +/- 1 and 40 +/- 1 degree C, the various filtration parameters were measured and samples of the feed and permeate were collected during steady state. It is seen that the "effective" pore size increases with temperature increase thereby increasing flux, sieving and fouling. Exploiting temperature effects can possibly help modify the sieving spectrum in membrane-based plasmapheresis.

Humans↗

PubMed1995

Is there a case for haemorheological screening in the haemocompatibility testing of materials?

Bio-interactions between a material and blood govern the compatibility of the material with the human body and, therefore, the single most important requirement for the blood interfacing implants/devices is haemocompatibility. The decisive events which control haemocompatibility occur at the molecular level and affect the various subphases of blood rheology. This effect on the already complex human blood rheology can be used to our advantage in the screening of blood-contacting materials. An attempt has been made in the present work to evaluate the haemocompatibility of materials based on changes in microrheological parameters of human blood. Samples of materials of equal surface area known to be haemocompatible (medical grade silicon, polyvinyl chloride from blood bags) and materials known to be extremely haemo-incompatible (pyrex glass, copper, cotton fabric, all commercial grade) were incubated at 37.4 degrees C in freshly drawn anticoagulated whole human blood, and changes in the haemorheological parameters (whole blood, plasma viscosity, intrinsic viscosity of red cells, platelet aggregation, albumin fibrinogen ratio) have been evaluated. The results of the study show that alterations in the haemorheological parameters are reliable indicators to the compatibility/incompatibility characteristics of well-known substances and that there is a case for haemorheological screening of biomaterials in the overall framework of haemocompatibility tests.

Absorption↗

PubMed1991

GABA/BZ-and NMDA-receptor interaction in digoxin-induced convulsions in rats.

Digoxin (7.5 micrograms icv) induced 'pop-corn' type of convulsions and 100% mortality. The GABA-ergic agents produced varying degree of protection against digoxin-induced neurotoxicity. Diazepam (4 mg/kg) offered significant protection whereas pentobarbital (5 mg/kg) and baclofen (5 mg/kg) markedly reduced per cent mortality, but ethanol (2 g/kg), progabide (50 mg/kg) and muscimol (0.5 mg/kg) as well as GABA (50 mg/kg) could not offer significant protection in doses used. GABA-ergic agonists; GABA, baclofen, diazepam and pentobarbital when administered along with MK-801 (0.5 mg/kg) a non-competitive NMDA antagonist, a potentiation of anticonvulsant action of MK-801 was observed. MK-801 showed potent anticonvulsant profile in dose range (0.25-1 mg/kg) studied. A synergistic influence of Mg2+ and K+ ions on NMDA receptor antagonism was also observed. A role of GABA-ergic facilitation and NMDA antagonism as a potential anticonvulsant approach in digoxin-induced convulsions in rats has been suggested.

Animals↗

PubMed1977

A study of antidepressant activity of some indole alkylamines.

The antidepressant characteristics of three indole alkylamines were investigated and compared with phenelzine and imipramine by utilising specific pharmacological tools like reserpine, amphetamine, tryptamine and tetrabenazine for determining their possible mechanism of action. Amongst the three indole compounds investigated, indole-3-(2-aminopropyl)-acetate (U-14 164E), indole-3(2-aminobutyl)-d-acetate (u-17 312E) and beta-phenethylhydrazine (phenelzine) produced complete antagonism to reserpine induced sedation, hypothermia as well as facilitation of convulsive seizures. Some of these features suggest that MAO inhibition might be a common mechanism of action of these indoles. The potentiation of CNS effects of tryptamine by these compounds is an outstanding feature of MAO inhibitors, while imipramine is ineffective. Qualitative differences between these indoles and imipramine are evident in the tetrabenazine test. The potentiation of amphetamine induced motor excitation and pentobarbitone narcosis has been explained.

Analgesia↗