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Biomedical subjects

S K Tiwari

Publications and source records attributed to S K Tiwari.

At least 19 recordsLinked to original sources
PubMed2006

Semiorganic nonlinear optical material for frequency doubling: preparation and properties of sodium p-nitrophenolate dihydrate (SPNP).

Sodium p-nitrophenolate (SPNP), a semiorganic nonlinear optical (NLO) material useful for frequency doubling in the IR region, has been synthesized. The solubility studies have been carried out in the temperature range 30-50 degrees C. Single crystals (size 12 mmx7 mmx4 mm) have been grown by slow evaporation of the saturated aqueous solution (methanol as solvent) at 30 degrees C. The lattice parameters of the grown crystals have been determined by single crystal X-ray diffraction technique. The UV-vis-NIR transmittance spectrum has been recorded in the range 200-1500 nm. The molecular structure was confirmed by FT-IR and FT-NMR. SPNP was thermally stable up to 103 degrees C as determined by TG/DTA curves. By a modified Kurtz and Perry method, the powder SHG efficiency was found to be five times that of KDP and its phase matching property was established. Laser damage threshold of SPNP was determined using a Nd:YAG laser.

Crystallization↗
PubMed2006

Studies on sorption properties of zeolite derived from Indian fly ash.

Indian fly ash has been completely converted to crystalline porous 13X zeolite by NaOH fusion at 600 degrees C followed by hydrothermal treatment at 105 degrees C for 20 h. Obtained materials were characterized by XRD, SEM and surface area measurement. Prepared material was used for the sorption study of different metal ions (Cu(2+), Co(2+) and Ni(2+)) at different pH, temperature. Thermodynamic data (DeltaS, DeltaH and DeltaG) corresponding to different metal ion uptake were evaluated from Langmuir equation. In all the experiment sorption capacity of prepared zeolite was found to be quite high than that of fly ash at acidic pH. However, the uptake selectivity order for both the materials is Cu(2+)>Co(2+)>Ni(2+).

Adsorption↗
PubMed2006

Prevalence study to elucidate the transmission pathways of Helicobacter pylori at oral and gastroduodenal sites of a South Indian population.

INTRODUCTION: Since the discovery of Helicobacter pylori (H. pylori), much progress has been made worldwide in the field of its epidemiology. In spite of these advancements, many aspects of epidemiology still remain unclear, particularly among populations with low socio-economic status. The present study was designed to elucidate the different routes of transmission of H. pylori in the Hyderabad (South India) population and to investigate the impact of certain factors, such as age, gender, and lifestyle. METHODS: Samples used for the study included saliva and biopsy samples of 400 symptomatic subjects from Hyderabad, India. The patients were retrospectively grouped, based on histopathology of the biopsy and 16S rRNA amplification of both saliva and biopsy as H. pylori positive and negative. RESULTS: This study showed that the prevalence of H. pylori in both saliva and biopsy samples increased with age. In addition, the H. pylori infection was found more commonly in the saliva and biopsy samples among males (64 percent and 60 percent, respectively) than females (53.3 percent and 64 percent, respectively). Similarly, 71.6 percent and 73.5 percent of those who consumed municipal water acquired H. pylori (which were respectively found in their saliva and biopsy samples) compared to a lesser proportion (12.6 percent and 12.6 percent, respectively) of those who consumed boiled or filtered water. The study also found that subjects who preferred home-cooked food (57.1 percent and 57.7 percent) showed a lower prevalence of H. pylori in saliva and biopsy samples, respectively, compared to those (80 percent and 88 percent) who frequently ate out. CONCLUSION: The results of the present study suggest that besides the oral-oral route, the transmission of H. pylori also takes place through the consumption of food prepared under unhygienic conditions. Consumption of municipal tap water also has a high impact in the transmission of H. pylori.

Adolescent↗
PubMed2005

Rapid diagnosis of Helicobacter pylori infection in dyspeptic patients using salivary secretion: a non-invasive approach.

INTRODUCTION: Current guidelines that recommend Helicobacter pylori eradication treatment without endoscopy in selected patients underscore the importance of non-invasive testing. The accuracy of saliva as a non-invasive specimen was compared with that of invasive tests in pretreatment diagnosis of H. pylori infection. METHODS: One hundred patients undergoing gastroscopy were grouped into 80 symptomatic and 20 asymptomatic subjects and were investigated for the presence of H. pylori in saliva and stomach. Samples tested comprised saliva and gastric biopsies collected from each patient. Exclusion criteria were history of peptic ulcer, bleeding ulcer, cancer or recent use of antibiotics, proton pump inhibitors and non-steroidal anti-inflammatory drugs. Two sets of primers homologous to 534 bp fragment of H. pylori DNA, which have been shown previously to be highly specific and sensitive, were used for the polymerase chain reaction (PCR) amplification. RESULTS: 72 (90 percent) of the symptomatic group and 10 asymptomatic subjects were infected with H. pylori in the stomach as determined by histology and direct PCR amplification of biopsy DNA obtained from each subject. H. pylori DNA was identified in the saliva of 70 (87.5 percent) symptomatic subjects and 12 (60 percent) asymptomatic control subjects. CONCLUSION: High rates of detection using saliva as a specimen indicate that saliva of the infected person could serve as a reliable non-invasive alternative to detect the presence of H. pylori infection in comparison to the currently available standard diagnostic tests.

Adult↗
PubMed2002

In vitro propagation of Lagerstromia parviflora Roxb. from adult tree.

A micropropagation protocol based on axillary bud proliferation has been developed from mature Lagerstromia parviflora adult tree. Nodal segments cultured on woody plant medium supplemented with 5.0 microl. BAP and 0.25 microm IAA gave maximum (86.9%) morphogenetic response. Proliferated shoots (10.7 per explants) were elongated to 3.9 cm within 6 weeks. In vitro produced micro-shoots were subjected to an IBA treatment (500 ppm for 2 min. dip) and placed under misting conditions for rooting. Misting beds were prepared with sand: soil (3:1) for 80.6% rooting and was acclimatized. Shoot length seems to be important to induce adventitious roots. The highest (91.7%) rooting was recorded on shoots ranging a length between 3.1-4.0 cm. Rooted and hardened plants were later transferred to poly bags and maintained in shadenet house. The protocol has the realizes capacity to produce 260 plants from a single explants within 10 months multiplication cycle.

Botany↗
PubMed2001

Studies on energetic compounds. Part 16. Chemistry and decomposition mechanisms of 5-nitro-2,4-dihydro-3H-1,2,4-triazole-3-one (NTO).

The present review deals with the chemistry and thermolysis of NTO and plausible decomposition pathways have been described. The decomposition of 5-nitro-2,4-dihydro-3H-1,2,4-triazole-3-one (NTO) induced by X-ray, UV, laser, photochemical irradiation has also been discussed. High-speed photographic studies of the impact responses of NTO are also included. The thermal decomposition of labelled NTO has also been described here. Methods of detection as well as safe disposal of NTO have also been mentioned.

Molecular Structure↗
PubMed1998

Reversal of sedative and clinicophysiological effects of epidural xylazine and detomidine with atipamezole and yohimbine in buffaloes (Bubalus bubalis).

The sedative and clinicophysiological effects of either xylazine (0.1 mg/kg) or detomidine (50 micrograms/kg) administered epidurally to groups of five buffaloes were reversed by the intravenous administration of either yohimbine (0.125 mg/kg) or atipamezole (10 micrograms/kg). Epidural xylazine or detomidine produced bradycardia, respiratory depression, ruminal stasis and hypothermia and these effects were completely reversed within five to 15 minutes after the intravenous administration of atipamezole or yohimbine, with no signs of excitement or resedation. Atipamezole reversed the effects of xylazine or detomidine more rapidly than yohimbine.

Adrenergic alpha-Agonists↗
PubMed1992

Helix aspersa neurons maintain vigorous electrical activity when co-cultured with intact H. aspersa ganglia.

1. Identified neurons from the right parietal lobe of the circumoesophageal ganglion of adult land snails, Helix aspersa, were isolated and placed in primary cell culture. 2. The individual neurons were removed from the right parietal lobe by microdissection without the aid of exogenous enzymes and plated on poly-L-lysine coated coverslip in normal Helix Ringer's solution conditioned with Helix circumoesphageal ganglia. The neurons become firmly attached to the substrate and begin to extend processes within 6 hr. 3. The cells show a dramatic increase in electrical activity when they are co-cultured with intact Helix circumoesophageal ganglia (1 ganglion/ml). Co-cultured neurons have resting potentials between -45 and -110 mV, comparable to in situ, show spontaneous action potential firing and respond to putative neurotransmitters. Heat-treated conditioned media was inactive. 4. When dopamine or serotonin (5-HT) are added, right parietal beating neurons, F14-F16 and F29-F32, (i) show a suppression of action potentials occurrence; (ii) a decrease in action potential amplitude and duration, and (iii) an increase in after-hyperpolarization. 5. Right parietal bursting neuron F1 in culture fire action potentials only in a beating mode. Dopamine addition to F1 suppresses action potential occurrence and causes an increase in action potential after-hyperpolarization, but there is only a small decrease in duration of action potentials and no significant change in action potential amplitude. 5-HT addition to F1 increases the occurrence of action potentials with little or no change in action potential shape. 6. This primary cell culture method is an efficient system for doing biochemical and electrophysiological studies on individual, identified neurons.

Action Potentials↗