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Biomedical subjects

G Rai

Publications and source records attributed to G Rai.

At least 19 recordsLinked to original sources
PubMed2005

Chitosan hydrochloride based microspheres of albendazole for colonic drug delivery.

Microspheres of chitosan hydrochloride (CH) were prepared in order to deliver albendazole specifically into the colon. Microspheres were prepared by an emulsion method using different ratios of drug and CH (1:1 to 1:5), agitation speeds (500 to 1500 rpm) and concentrations of glutaraldehyde in toluene as the cross-linking agent (0.25 to 1.0% w/v). The effect of polymer concentration, stirring rate and concentration of cross-linking agent on the particle size and drug loading was studied. With an increase in CH concentration, the average particle size was increased. Increased agitation speed reduced the size of the microspheres but higher agitation speed resulted in irregularly shaped microspheres. Increasing the concentration of cross-linking agent produced more regularly shaped microspheres of smaller size. The drug loading was highest at a drug: CH ratio of 1:3, stirring speed 1000 rpm and 0.75% w/v concentration of cross-linking agent. The effect of CH concentration on in vitro drug release from the microspheres was evaluated in simulated g.i.t fluids. A comparative in vitro drug release study of the optimized formulation was carried out in simulated colonic fluid, with and without 2% rat caecal content. The drug release in 24 h was 48.9% in colonic fluid without rat caecal content, and 76.5% in colonic fluid with rat caecal contents.

Albendazole↗
PubMed2003

Near-threshold production of the multistrange Xi- hyperon.

The yield for the multistrange Xi(-) hyperon has been measured in 6A GeV Au+Au collisions via reconstruction of its decay products pi(-) and Lambda, the latter also being reconstructed from its daughter tracks of pi(-) and p. The measurement is rather close to the threshold for Xi(-) production and therefore provides an important test of model predictions. The measured yield for Xi(-) and Lambda are compared for several centralities. In central collisions the Xi(-) yield is found to be in excellent agreement with statistical and transport model predictions, suggesting that multistrange hadron production approaches chemical equilibrium in high baryon density nuclear matter.

Journal Article↗
PubMed2003

Comparison of source images for protons, pi-'s, and lambda's in 6A GeV Au+Au collisions.

Source images are extracted from two-particle correlations constructed from strange and nonstrange hadrons produced in 6A GeV Au+Au collisions. Very different source images result from pp vs p Lambda vs pi(-)pi(-) correlations. Scaling by transverse mass can describe the apparent source size ratio for p/pi(-) but not for Lambda/pi(-) or Lambda/p. These observations suggest important differences in the space-time emission histories for protons, pions, and neutral strange baryons produced in the same events.

Journal Article↗
PubMed2002

Longitudinal flow of protons from (2-8)A GeV central Au+Au collisions.

Rapidity distributions of protons from central 197Au+197Au collisions measured by the E895 Collaboration in the energy range from (2-8)A GeV at the Brookhaven AGS are presented. Longitudinal flow parameters derived using a thermal model including collective longitudinal expansion are extracted from these distributions. The results show an approximately linear increase in the longitudinal flow velocity, (L), as a function of the logarithm of beam energy.

Journal Article↗
PubMed2001

Model-independent source imaging using two-pion correlations in (2 to 8)a GeV Au+Au collisions.

We report a particle source imaging analysis based on two-pion correlations in high multiplicity Au+Au collisions at beam energies between 2A and 8A GeV. We apply the imaging technique introduced by Brown and Danielewicz, which allows a model-independent extraction of source functions with useful accuracy out to relative pion separations of about 20 fm. The extracted source functions have Gaussian shapes. Values of source functions at zero separation are almost constant across the energy range under study. Imaging results are found to be consistent with conventional source parameters obtained from a multidimensional Hanburg-Brown-Twiss analysis.

Journal Article↗
PubMed2001

Directed flow of lambda hyperons in (2-6 )A GeV Au+Au collisions.

Directed flow measurements for Lambda hyperons are presented and compared to those for protons produced in the same Au+Au collisions (2A, 4A, and 6A GeV; b<5-6 fm). The measurements indicate that Lambda hyperons flow consistently in the same direction but with smaller magnitudes. A strong positive flow [for Lambdas] has been predicted in calculations which include the influence of the Lambda-nucleon potential. The experimental flow ratio Lambda/p is in qualitative agreement with expectations (approximately 2/3) from the quark counting rule at 2A GeV but is found to decrease with increasing beam energy.

Journal Article↗
PubMed2001

Human retinal S-antigen: T cell epitope mapping in posterior uveitis patients.

Uveitis, an intraocular inflammatory disease which affects the uveal tract and the retina of the eye in humans, is one of the major causes of visual impairment. Posterior uveitis is often associated with inflammation of the retina and vitreous. Unfortunately, etiological diagnosis of the disease is not possible in the majority of patients. It is generally felt that an autoimmune mechanism may be involved in so-called idiopathic cases. The role of retinal S-antigen, its 20 linear peptides spanning the entire sequence, and 2 additional peptides, known to be uveitopathogenic in experimental animals, was studied in 26 patients with uveitis. Lymphocyte proliferative response was tested in vitro to identify the epitopes of S-antigen involved and to establish their role in the pathogenesis of uveitis. Of 26 uveitis patients tested, 11 showed a significant T cell proliferative response in vitro to at least 1 antigen used. None among the controls showed any response to the peptides or native S-antigen used in this study. We have found that uveitis patients respond most frequently to peptide 4 (61--80), peptide 5 (81--100), peptide 8 (141--160), peptide 9 (161--180), peptide 12 (221--240), and peptide 13 (241--260) of the human S-antigen. These results further confirm that autoimmunity to retinal S-antigen may play a role in the etiopathogenesis of a subset of patients with idiopathic uveitis.

Adolescent↗
PubMed2001

Cytokines in posterior uveitis: an update.

T helper (Th) lymphocytes differentiate into two distinct subsets--Th1 and Th2--as defined by functional abilities and cytokine profiles. The functional differences between Th subsets are explained primarily through the activities of the cytokines they secrete. Interferon-gamma (IFN-gamma) is the signature cytokine of Th1 cells, which also produce interleukin-2 (IL-2) and tumor necrosis factor-beta (TNF-beta). IL-4 is the corresponding signature cytokine of Th2 cells, which also secrete IL-5, IL-6, IL-9, and IL-13. Recently, a few transcription factors have been identified that not only control the expression of cytokines of a particular type but also repress cytokines of other types. Human Th1 and Th2 cells not only produce a different set of cytokines but also exhibit distinct functional properties and the preferential expression of some activation markers. Pathophysiologically, the two subsets have been found to be mutually antagonistic. Various Th1 and Th2 cytokines appear to play an important role in the etiopathogenesis of posterior uveitis and its animal model, experimental autoimmune uveitis (EAU). The exact contribution of these mediators to uveitis remains to be defined. Recent studies suggest that a shift from Th1- to Th2-dominated response could be of therapeutic benefit. This review evaluates various studies in which uveitopathogenic and therapeutic potentials of various Th1 and Th2 cytokines have been investigated.

Animals↗
PubMed2001

Seasonal distribution of enteropathogens detected from diarrheal stool and water samples collected in Kathmandu, Nepal.

A total of 334 diarrheal fecal samples (from 210 males and 124 females) collected in Kathmandu, Nepal, were studied for various kinds of enteropathogens. Overall, 33% (111/334) fecal samples were positive for one or more enteropathogens. There was no difference in detection rates between males and females. Enteropathogen detection rates in summer, winter, spring, and autumn were 61% (40/66), 52% (45/87), 31% (25/81), and 25% (25/100), respectively. Altogether eight species of bacteria, three genera of viruses, and five species of protozoan parasites were detected with considerable seasonal variations. Among the bacterial isolates, enteropathogenic Escherichia coli topped the list followed by Vibrio sp. Only one sample had Shigella (S. sonnei). Rotavirus type A was the most frequently detected among the enteric viruses, followed by human enterovirus and human adenovirus, respectively. Among the enteric protozoan parasites, Giardia intestinalis was the most frequently detected followed by Cryptosporidium parvum. Detection of bacterial and protozoan pathogens showed a slightly high tendency in the summer season compared with that in the other seasons (p>0.05), whereas the detection of viruses was significantly high in the winter season (p<0.05). Of the total 57 water samples, 43 (75%) showed one or more bacterial species out of which 51% (22/43) were E. coli. Among the E. coli isolates, 68% were EPEC. Enterohemorrhagic E. coli (O157) was not detected.

Adolescent↗
PubMed2001

Role of cytokines in experimental and clinical uveitis.

Uveitis is a major cause of visual impairment. Experimental autoimmune uveitis mimics the clinical conditions of posterior uveitis in many ways. T-cells (particularly CD4+ helper-T-cells) have been shown to play an important role in pathogenesis of experimental and clinical uveitis. Based on the pattern of cytokine they secrete, CD4+ helper cells have been divided into Th1 and Th2 subsets. Various Th1 and Th2 cytokines appear to be involved in the pathogenesis and/or recovery from uveitis. This article discusses in detail the uveitopathogenic and therapeutic potential of Th1 and Th2 cytokines in experimental and clinical uveitis.

Animals↗
PubMed2000

Semi-inclusive lambda and K(S) production in p-Au collisions at 17.5 GeV/c

The first detailed measurements of the centrality dependence of strangeness production in p-A collisions are presented. Lambda and K(S) dn/dy distributions from 17.5 GeV/ c p-Au collisions are shown as a function of "grey" track multiplicity and the estimated number of collisions, nu, made by the proton. The nu dependence of the Lambda yield deviates from a scaling of p-p data by the number of participants, increasing faster than this scaling for nu</=5 and saturating for larger nu. A slower growth in K(S) multiplicity with nu is observed, consistent with a weaker nu dependence of K&Kmacr; production than YK production.

Journal Article↗
PubMed2000

Contamination of soil with helminth parasite eggs in Nepal.

Contamination of soil with helminth eggs in Kathmandu Valley (n=122) and outside of Valley (n=34) in Nepal was investigated with the use of centrifugal floatation technique using sucrose solution (sp gr 1.200). The overall soil contamination rate was 36.5% (57/156). The prevalence was uniform in Kathmandu Valley (36.9%) and outside of the valley (35.3%). A mean of six helminth eggs per sample were detected out of which more than half were embryonated (potentially infective). In Kathmandu Valley, soil contamination rate was higher (48.3%) during wet season compared with that observed in dry season (33.3%) but without significant difference (p>0.05). Multiple species of helminth eggs were detected in 22.8% of total positive samples (n=57). Altogether five species of nematoda (Ascaris lumbricoides, Toxocarta sp, Trichuris trichiura, Capillaria sp and Trichostrongylus sp) and two species of cestoda (Hymenolepis nana and H. diminuta) were recovered. A. lumbricoides was predominant in Kathmandu Valley while Trichostrongylus was the commonest one in outside of valley.

Animals↗
PubMed2000

Modulation of antigenicity of mycelial antigens during developmental cycle of Karnal bunt (Tilletia indica) of wheat.

Indirect enzyme linked immunosorbent assays (ELISA) were developed using polyclonal antibodies against soluble cytoplasmic (SCA) and insoluble cell wall antigens (ICWA) for monitoring modulation of mycelial antigens during growth cycle of T. indica. With SCA, continuous decrease in ELISA reactivity was observed in maturing fungus cultures, suggesting that SCA were expressed predominantly during early vegetative phase and their decreasing role was apparent as the fungus matures possibly towards sporogenous mycelium. In case of ICWA, the reaction profile showed an increase up to exponential phase of growth probably due to increase in the cell division and branching of mycelium. But later, ICWA antibody reactivity was decreased which may be due to conversion of mycelial phase to sporogenous phase, a quiescent stage of growth. Characterization of changes in antigenic configuration during developmental cycle of Tilletia indica by these antibodies could prove to be useful in identification of developmentally related and virulence marker(s).

Antigens, Fungal↗
PubMed1999

High Toxoplasma seroprevalence associated with meat eating habits of locals in Nepal.

A serosurvey of Toxoplasma gondii infection in apparently healthy subjects (n = 404) living in Achham (n = 215) and Dang (n = 189) districts in western Nepal was carried out. An interview with 249 participants, each representing a household, was also conducted. This interview pertained to their meat eating habits and the keeping of cats in their houses. Toxoplasma antibodies were detected by using the microlatex agglutination test. The overall seroprevalence was 65.3% with no significant difference in the two districts (Achham: 66.9% and Dang: 63.5%) included (p = 0.546). Females and the Indo-Aryan ethnic-group showed marginally higher prevalence compared with their male (p = 0.545) and Tibeto-Burman (p = 0.075) counterparts. The majority of the infections was found to have occurred during childhood. The frequency of meat eating in western and eastern regions differed greatly (p = 0.000) with the people in the eastern region being frequent meat eaters than those in the western region. About one-third of the subjects, all Indo-Aryans, in the western region had the raw meat eating habit but none in the eastern region. Approximately 7.0% of households in both western and eastern regions kept cats. The present findings demonstrated a typical role of meat eating habits of people in the high Toxoplasma seroprevalence in Nepal.

Adolescent↗
PubMed1998

Toxoplasma antibody prevalence in Nepalese pregnant women and women with bad obstetric history.

Sera from randomly selected 345 pregnant Nepalese women aged 16-36 years and 13 women with bad obstetric history (BOH) were tested for the presence of Toxoplasma antibodies using microlatex agglutination (MLA) and ELISA methods. The overall prevalence was 55.4% (191/345). Prevalence was slightly higher (59.0%) in older age-group (27-36 years) compared with younger age-group (16-26 years) (52.2%). No significant difference in antibody prevalence in women belonging to two different ethnic-groups (Tibeto-Burmans 57.8%, Indo-Aryans 52.7%) was observed (p>0.05). MLA antibody titer ranged from 1:16 to 1:2,048. Over three-fourth of the women showed either high (1:510 or over) or low (1:16 or 1:32) antibody titer. Three percent (6/191) of MLA antibody positive subjects had Toxoplasma IgM antibodies by IgM-ELISA. All six IgM antibody positive pregnant women had MLA antibody titer of over 1:510. Of the total 13 women with BOH, 5 (38.5%) had Toxoplasma antibodies of which 2 (40.0%) were positive for Toxoplasma-IgM antibodies.

Adolescent↗
PubMed1998

Continuous hyperfractionated accelerated radiotherapy in advanced head and neck malignancies.

58 patients of advanced head and neck cancer were treated by continuous hyperfractionated accelerated radiotherapy (study group) or conventional radiotherapy (control group). The study group of 29 patients had 26/29 (89%) of patients of stage T3 and T4 with 12/29 (41% 0) > N2 disease. The schedule employed was 1.5 Gy 3 times a day in 36 fractions on 12 treatment days without stopping for weekends. The spinal dose has been kept at 40.5 Gy and interfraction interval has been strictly kept at 6 hrs. Clinical, as well as radiological assessment has been encouraging with 23/29 (79.13%) of patients achieving complete regression of the primary tumor and nodal disease. Compared to the conventionally treated controls this value has been significant (P value < 0.001). In stage III disease tumor control has been in 9/10 (90%) cases, while in stage IV disease in 14/19 (73.68%) cases. The acute mucosal reactions have been found to be severe in these cases with 18/29 i.e. 62.06% suffering from grade III reactions. Nasogastric feeding was required in 25.92% of patients.

Adult↗