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Biomedical subjects

U Banerjee

Publications and source records attributed to U Banerjee.

At least 55 records · Page 3Linked to original sources
PubMed1995

Sudden spurt of cryptococcosis at a tertiary care hospital at New Delhi between December 1994 to February 1995.

In a short span of three months, nine patients of cryptococcal infection were diagnosed at the All India Institute of Medical Sciences (AIIMS), New Delhi with varied clinical presentation. Predisposing factors could be ascertained in two patients only. The diagnosis was based on the direct demonstration of the organism followed by successful culture supported by histopathology (in one patient) and radiology. The specific antigen was also detected in the body fluids. The increased awareness and greater suspicion helped in the diagnosis of these patients. Those who were diagnosed early, responded well with specific antifungal therapy.

Adolescent↗
PubMed1994

Characterization of Star and its interactions with sevenless and EGF receptor during photoreceptor cell development in Drosophila.

Loss-of-function mutations in Star impart a dominant rough eye phenotype and, when homozygous, are embryonic lethal with ventrolateral cuticular defects. We have cloned the Star gene and show that it encodes a novel protein with a putative transmembrane domain. Star transcript is expressed in a dynamic pattern in the embryo including in cells of the ventral midline. In the larval eye disc, Star is expressed first at the morphogenetic furrow, then in the developing R2, R5, and R8 cells as well as in the posterior clusters of the disc in additional R cells. Star interacts with Drosophila EGF receptor in the eye and mosaic analysis of Star in the larval eye disc reveals that homozygous Star patches contain no developing R cells. Taken together with the expression pattern at the morphogenetic furrow, these results demonstrate an early role for Star in photoreceptor development. Additionally, loss-of-function mutations in Star act as suppressors of R7 development in a sensitized genetic background involving the Son of sevenless (Sos) locus, and overexpression of Star enhances R7 development in this genetic background. Based on the genetic interactions with Sos, we suggest that Star also has a later role in photoreceptor development including the recruitment of the R7 cell through the sevenless pathway.

Amino Acid Sequence↗
PubMed1993

Binding of the Ras activator son of sevenless to insulin receptor substrate-1 signaling complexes.

Signal transmission by insulin involves tyrosine phosphorylation of a major insulin receptor substrate (IRS-1) and exchange of Ras-bound guanosine diphosphate for guanosine triphosphate. Proteins containing Src homology 2 and 3 (SH2 and SH3) domains, such as the p85 regulatory subunit of phosphatidylinositol-3 kinase and growth factor receptor-bound protein 2 (GRB2), bind tyrosine phosphate sites on IRS-1 through their SH2 regions. Such complexes in COS cells were found to contain the heterologously expressed putative guanine nucleotide exchange factor encoded by the Drosophila son of sevenless gene (dSos). Thus, GRB2, p85, or other proteins with SH2-SH3 adapter sequences may link Sos proteins to IRS-1 signaling complexes as part of the mechanism by which insulin activates Ras.

Adaptor Proteins, Signal Transducing↗
PubMed1993

Vector potential of the German cockroach in dissemination of Pseudomonas aeruginosa.

Survival time studies of Pseudomonas aeruginosa in cockroaches (Blattella germanica) were carried out under standard laboratory conditions. Cockroaches were fed with graded doses (10(2), 10(5) or 10(7) per insect) of P. aeruginosa. Depending on the excretion of P. aeruginosa the cockroaches were categorized as non-excretors, intermittent excretors or continuous excretors. When a dose of 10(2) P. aeruginosa was used all the insects were non-excretors but with doses of 10(5) or 10(7) per insect, P. aeruginosa multiplied in the gut of the cockroaches and was excreted for up to 114 days. The significance of these findings is discussed.

Animals↗
PubMed1993

The strawberry notch gene functions with Notch in common developmental pathways.

Genetic and phenotypic analysis of strawberry notch suggests that its gene product is required during embryogenesis and oogenesis, and for the development of the eye, wing and leg. Several lines of evidence suggest that strawberry notch participates together with Notch in many common pathways. A number of strawberry notch mutant phenotypes are similar to those of Notch mutants and can be rescued by an extra copy of wild-type Notch. In addition, mutations in strawberry notch interact strongly with Notch mutants in a tissue-specific manner. Mutations in the strawberry notch and Notch loci also show very similar interactions with genes like Hairless, Delta, groucho, Serrate, and deltex that have all been proposed to participate in Notch related pathways. The genetic evidence presented here suggests that strawberry notch participates with members of the Notch pathway in facilitating developmentally relevant cell-cell communications.

Animals↗
PubMed1993

Differential cell-mediated immune response to S. mutans in children with low and high dental caries.

Role of cell-mediated immune response (CMI) in dental caries was studied in 171 subjects, comprising of 86 children with low caries (LC), 31 with high caries (HC), and 54 age matched controls. [3H]thymidine mediated lymphoblast transformation test (LTT) using mutans streptococci antigen as stimulant was used to study the stimulation index (SI) of in vitro cultured lymphocytes from these children. The analysis revealed low stimulation index in high caries children whereas low caries children exhibited high stimulation index normally ranging between 2 to 6. The findings indicated that low caries children had strong CMI response as compared to high caries children. Although, the findings are based on limited number of samples, it certainly lays emphasis on protective or regulatory role of CMI in different phases of dental caries.

Adolescent↗
PubMed1992

Neuronal development in the Drosophila retina: the sextra gene defines an inhibitory component in the developmental pathway of R7 photoreceptor cells.

Mutations in a gene called sextra (sxt) have been isolated. Loss of one copy of sxt promotes R7 photoreceptor cell development in a genetically sensitized background, while loss of both copies results in precursors of non-neuronal cone cells transforming into R7 cells. The requirement for sxt function is cell-autonomous. The transformation of cone-cell precursors into R7 cells occurs independently of the sevenless signal. However, the R7 precursor becomes neuronal in an sxt/sxt mutant only in a wild-type sevenless background. The genetic analysis of sxt suggests that it plays an inhibitory role, preventing cone cells from becoming neuronal. Additionally, sxt functions in R7 precursors, but the sevenless signal is essential for specification of this fate, since loss of sextra alone is unable to impart a neural fate to this cell.

Animals↗
PubMed1992

The Son of sevenless gene product: a putative activator of Ras.

The Son of sevenless (Sos) gene functions in signaling pathways initiated by the sevenless and epidermal growth factor receptor tyrosine kinases. The Sos gene has now been isolated and sequenced. Its product is a 1595-amino acid protein similar to the CDC25 protein in Saccharomyces cerevisiae, a guanine nucleotide exchange factor that activates Ras. These results imply a role for the ras pathway in Drosophila neuronal development.

Amino Acid Sequence↗
PubMed1992

The housefly (Musca domestica) as a carrier of pathogenic microorganisms in a hospital environment.

Houseflies have long been regarded as potential carriers of microorganisms. Since pathogenic microorganisms are widespread in the hospital environment, there is abundant opportunity for flies to become contaminated and, in turn, to contaminate the patient environment. In the present study, an attempt was made to isolate and identify pathogenic bacteria, fungi and parasites from the housefly Musca domestica collected in the surgical ward of the All India Institute of Medical Sciences Hospital and also in a remote residential area located 5 km from the hospital. A total of 113 flies were collected: 65 from a surgical ward (test) and 48 from a residential area for comparison. Ten genera of bacteria were isolated from the test group of flies compared with nine from the control group. In primary isolations, it was observed that the load of bacteria carried by the test group of flies was significantly more (P less than 0.001) than for the control flies. Pseudomonas aeruginosa, Enterococcus faecalis and viridans streptococci were isolated only from the test flies. The isolation rate of Staphylococcus aureus was significantly higher (P less than 0.001) in test houseflies than in the control houseflies. There was no significant difference in isolation of parasitic ova and cysts from test and control houseflies. Candida spp. were isolated in almost equal numbers from both groups of houseflies, yet none of these was Candida albicans. Houseflies therefore may act as vectors of potentially pathogenic bacteria in a hospital environment.

Animals↗
PubMed1992

Vector potential of hospital houseflies with special reference to Klebsiella species.

The vector potential of houseflies (Musca domestica) for Klebsiella spp. was investigated. Klebsiella spp. (mostly Klebsiella pneumoniae) were isolated from 36.7% of hospital flies and 28.1% of infected wounds of patients. Antibiograms of Klebsiella spp. showed that 82.0% of isolates from hospital flies and 96.3% from infected wounds were resistant to four or more commonly used antimicrobials. In contrast, from the control group, only 8.7% klebsiella isolates showed similar antimicrobial resistance pattern (P less than 0.001). Similar strains of Klebsiella spp. were encountered among patients and hospital houseflies. The results indicate that flies in the hospital environs are potential vectors of hospital resistant strains of Klebsiella spp.

Animals↗
PubMed1992

Humoral immunity status in patients with complicated pregnancies.

Serum immunoglobulin levels of 136 females inclusive of 20 non-pregnant volunteers, 21 normal pregnant mothers and 95 cases with complicated pregnancies were studied by radial immunodiffusion technique. Compared to normal western values immunoglobulin M levels were higher in 132 out of total 136 cases, immunoglobulin G levels were higher in 65 out of 95 cases with complicated pregnancies the majority of which included cases of eclampsia (16 cases), pre-eclamptic toxaemia (21 cases) and pre-eclamptic toxaemia with antepartum haemorrhage (11 cases) and immunoglobulin A levels were normal in all except 11 cases comprising normal pregnancy (1 case), eclampsia (3 cases), pre-eclamptic toxaemia (5 cases) and pregnancy with hypertension (2 cases).

Antibody Formation↗
PubMed1991

Genetic dissection of a neurodevelopmental pathway: Son of sevenless functions downstream of the sevenless and EGF receptor tyrosine kinases.

We have isolated a dominant mutation in a gene called Son of sevenless (Sos) that is an allele-specific suppressor of the sevenless phenotype. This suppressor function is autonomously required in R7 and is sensitive to the dosage of the Sos and bride of sevenless genes. Loss-of-function alleles of Sos are recessive lethals, but in the eye Sos has a role in R cell development. Mutations in Sos also interact with the Ellipse allele of the Drosophila EGF receptor. We propose a model suggesting that the Sos product is downstream of sevenless and the EGF receptor, and that the dominant suppression results from the overexpression or increased activity of the gene product.

Alleles↗
PubMed1991

Nosocomial infections: cockroaches as possible vectors of drug-resistant Klebsiella.

The possibility that hospital cockroaches may act as vectors of drug-resistant Klebsiella spp. was investigated during Nov 1985 to April 1989, at the All India Institute of Medical Sciences (AIIMS) hospital. Klebsiella spp. (majority Klebsiella pneumoniae) were isolated from 28.3% of hospital cockroaches and 28.1% of infected wounds of patients. Most of Klebsiella isolates from patients (96.3%), and hospital cockroaches (85.9%) showed multiple drug resistance to four or more antimicrobials. Similar strains of Klebsiella spp. were encountered among patients and hospital cockroaches. These findings suggest that hospital cockroaches may act as vectors of drug-resistant Klebsiella spp. and may contribute to the epidemiology of nosocomial infections.

Animals↗
PubMed1991

Human cutaneous myiasis due to mixed infestation in a drug addict.

Soft tissue infestation by maggots of flies (myiasis) is a well-recognized complication of neglected wounds. Mixed infestation by larvae of more than one species of fly is a rarity. We report, for the first time in India, one such case of cutaneous myiasis due to mixed infestation--in this instance by Chrysomya bezziana and Sarcophaga sp. in a drug addict.

Adult↗