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Biomedical subjects

J Banerji

Publications and source records attributed to J Banerji.

At least 19 recordsLinked to original sources
PubMed2005

Phased array 1-to-N-way resonator with a convex mirror for phase conjugation.

Phased array 1-to-N-way resonators can be relevant in the realization of high output powers from semiconductor laser arrays and have significant advantages over Talbot resonators. However, depending on the number of array elements, the intracavity power density on the output facet can be high, resulting in catastrophic optical mirror damage. We present a variant of the original design that overcomes these power density problems while maintaining the desirable phase-locking and power-combining properties.

Journal Article↗
PubMed2000

The reversible antifertility effect of Piper betle Linn. on Swiss albino male mice.

To study the antifertility effect of an extract (alcoholic) of the leaf-stalk of Piper betle Linn., one set of experiments with two different doses in Swiss male albino mice were evaluated. Initially, 500 mg of the leaf-stalk extractive for 30 days and then 1000 mg for next 30 days/animal/day/kg body weight were administered orally. The extract reduced fertility to 0% within 60 days. Suppression of cauda epididymal sperm count and motility (p <0.05) was observed. Biochemical parameters did not show any marked alterations in testosterone content in serum nor 17beta-hydroxysteroid dehydrogenase (17beta-HSD) activity in testes although fructose content in seminal vesicles was reduced as are the weights of reproductive organs. The cholesterol content in testes increased, although not appreciably. After cessation of drug (plant extract) treatment, the altered parameters recovered. Results suggest that the contraceptive effect of the extract of leaf-stalk of Piper betle Linn. is mainly on the maturation process of spermatozoa in epididymides without influencing hystemic hormonal profiles. Withdrawal of the extract restored all altered parameters including organ weights and fertility after 60 days.

17-Hydroxysteroid Dehydrogenases↗
PubMed2000

Pre-clinical toxicity evaluation of leaf-stalk extractive of Piper betle Linn. in rodents.

Studies on pre-clinical toxicity were undertaken to determine the haematological and biochemical changes after administration of alcoholic extract of leaf-stalk of P. betle in rats and mice. Acute and chronic toxicity experiments were performed on mice and rats according to WHO protocol. Different doses of plant extractive were administered for toxicity studies on short and long term basis. Haematological, biochemical profiles and enzymatic studies (transaminases and phosphatases) indicated that the drug (plant extractive) was devoid of toxicity.

Animals↗
PubMed1999

Nitric oxide and Drosophila development.

Mechanisms controlling the transition of precursor cells from proliferation to differentiation during organism development determine the distinct anatomical features of tissues and organs. NO may mediate such a transition since it can suppress DNA synthesis and cell proliferation. Inhibition of NOS activity in the imaginal discs of Drosophila larvae results in hypertrophy of tissues and organs of the adult fly, whereas ectopic overexpression of NOS has the reciprocal, hypotrophic, effect. Furthermore, NO production is crucial for the establishment of ordered neuronal connections in the visual system of the fly, indicating that NO affects the acquisition of the differentiated phenotype by the neural tissue. Increasing evidence points to a broad role that NO may play in animal development by acting as an essential negative regulator of precursor cell proliferation during tissue and organ morphogenesis.

Animals↗
PubMed1998

The immune response to soluble D10 TCR: analysis of antibody and T cell responses.

In order to evaluate the potential of TCR as vaccines for immunomodulation, the immunogenicity of soluble versions of D10 TCR has been investigated in mice. Soluble D10 TCR containing the extracellular domains were produced either as dual chain (dc) TCR lacking transmembrane and cytoplasmic regions or as a TCR-IgG1 chimeric protein. Soluble single chain (sc) D10 TCR contained only the Valpha and Vbeta segments joined by a peptide linker. Syngeneic D10 dcTCR or D10 TCR-IgG1 immunizations of AKR mice induced antibody responses to D10 clonotypic epitopes and to constant region epitopes that are not exposed on D10 cells. Only clonotypic antibodies were produced after D10 scTCR immunizations. Immunization of AKR mice with D10 dcTCR and D10 TCR-IgG1 primed I-Ak- and I-Ek-restricted CD4+ T cells recognizing constant region epitopes, but there was no detectable response to the variable region. Comparison of the in vitro proliferative responses of CD4+ T cells from D10 scTCR-primed H-2 congenic mice revealed that H-2u was a responder haplotype for the variable region. How the immunogenicity of particular regions of the TCR appears to be shaped by tolerance induction in vivo and the implications for immunotherapy with soluble TCR vaccinations are discussed.

Adjuvants, Immunologic↗
PubMed1997

Conformational integrity and ligand binding properties of a single chain T-cell receptor expressed in Escherichia coli.

We recently showed that a soluble, heterodimeric murine D10 T-cell receptor (TCR) (Valpha2Calpha, Vbeta8.2Cbeta) expressed in insect cells binds both Vbeta8.2-specific bacterial superantigen staphylococcal enterotoxin C2 (SEC2) and a soluble, heterodimeric major histocompatibility complex class II I-Ak.conalbumin peptide complex with a low micromolar affinity. To define further the structural requirements for the TCR/ligand interactions, we have produced in Escherichia coli a soluble, functional D10 single chain (sc) TCR molecule in which the Valpha and Vbeta domains are connected by a flexible peptide linker. Purified and refolded D10 scTCR bound to SEC2 and murine major histocompatibility complex class II I-Ak.conalbumin peptide complex with thermodynamic and kinetic binding constants similar to those measured for the baculovirus-derived heterodimeric D10 TCR suggesting that neither the TCR constant domains nor potential N- or O-linked carbohydrate moieties are necessary for ligand recognition and for expression and proper folding of the D10 scTCR. Purified D10 scTCR remained soluble at concentrations up to 1 mM. Circular dichroism and NMR spectroscopy indicated that D10 scTCR is stabilized predominantly by beta-sheet secondary structure, consistent with its native-like conformation. Because of its limited size, high solubility, and structural integrity, purified D10 scTCR appears to be suitable for structural studies by multidimensional NMR spectroscopy.

Amino Acid Sequence↗
PubMed1997

Affinity and kinetics of the interactions between an alphabeta T-cell receptor and its superantigen and class II-MHC/peptide ligands.

Immune activation is mediated by a specific interaction between the T-cell receptor (TCR) and an antigenic peptide bound to the major histocompatibility complex (MHC). T-cell activation can also be stimulated by superantigens which bind to germline-encoded variable domain sequences of certain TCR beta-chains. We have used a surface plasmon resonance biosensor to characterize the molecular interactions between a class II-restricted alphabeta TCR and its superantigen and MHC/peptide ligands. The extracellular domains of the murine D10 TCR (Valpha2, Vbeta8.2) were expressed in insect cells and secreted as a disulfide-linked heterodimer. In the absence of MHC class II, purified soluble D10 TCR bound to Staphylococcus aureus enterotoxin C2 with an association rate of 1.69+/-0.12 x 10(4)M(-1) sec(-1) and a dissociation rate of 1.9+/-0.47 x 10(-2) sec(-1), giving a dissociation constant of 1.1 microM. Binding of the TCR to S. aureus enterotoxin B was barely detectable and could not be measured accurately due to the rapid dissociation rate. Soluble D10 TCR also bound to a soluble murine MHC class II I-A(k) molecule containing a fused antigenic conalbumin peptide and complementary leucine zipper sequences to facilitate efficient chain pairing. The purified I A(k) chimera specifically stimulated proliferation of the D10 T-cell clone, and bound to immobilized soluble D10 TCR with an association rate of 1.07+/-0.19 x 10(4)M(-1)sec(-1) and a dissociation rate of 2.2+/-0.65 x 10(-2) sec(-1), giving a dissociation constant of 2.1 microM.

Animals↗
PubMed1996

Immunization with soluble BDC 2.5 T cell receptor-immunoglobulin chimeric protein:antibody specificity and protection of nonobese diabetic mice against adoptive transfer of diabetes by maternal immunization.

The BDC 2.5 T cell clone is specific for pancreatic beta-cell antigen presented by I-Ag7, and greatly accelerates diabetes when injected into 10-21-d-old nonobese diabetic (NOD) mice. The BDC 2.5 T cell receptor (TCR) has been solubilized as a TCR-IgG1 chimeric protein. All NOD mice immunized against BDC 2.5 TCR-IgG1 produced antibodies recognizing TCR C alpha/C beta epitopes that were inaccessible on the T cell surface. 56% of the mice produced antibodies against the BDC 2.5 clonotype that specifically blocked antigen activation of BDC 2.5 cells. We have used the adoptive transfer model of diabetes to demonstrate that maternal immunization with soluble TCR protects young mice from diabetes induced by the BDC 2.5 T cell clone.

Adoptive Transfer↗
PubMed1990

Interferon gamma response region in the promoter of the human DPA gene.

The interferon gamma (IFN-gamma) response region of the human class II major histocompatibility complex gene, DPA, has been localized to a 52-base-pair (bp) DNA fragment in the proximal promotor at -107 to -55 bp after transfection into HeLa cells of a series of 5', 3', and gap deletion mutants linked to a reporter gene, human growth hormone, as well as of synthetic oligonucleotides fused to the heterologous promoter thymidine kinase. The 52-mer sequence contains the X and Y box elements conserved in all class II genes; their presence is indispensable for IFN-gamma inducibility. Furthermore, an additional 5 bp immediately 5' of the X box of the DPA gene are necessary and sufficient for IFN-gamma induction. This region may contain an IFN-gamma response element. A closely related sequence has also been found in the vicinity of the critical deletion sites of three other well-studied class II gene promoters, all of which require a much longer sequence 5' of the X box. A fourth element, the W element, located about 15 bp 5' of the X box in all class II genes, is clearly of little importance in IFN-gamma inducibility of the DPA gene.

Base Sequence↗
PubMed1990

A gene pair from the human major histocompatibility complex encodes large proline-rich proteins with multiple repeated motifs and a single ubiquitin-like domain.

A large number of genes has been identified previously between the class I and class II gene families within the class III region of the human major histocompatibility complex. The complete sequences of two of these genes, BAT2 and BAT3 (where BAT is HLA-B-associated transcript), which are closely linked, were determined from cDNA clones. The putative BAT2 and BAT3 proteins are 228 and 110 kDa, respectively, and do not appear to be members of any known family of proteins. However, BAT3 contains an amino-terminal ubiquitin-like domain. Both BAT2 and BAT3 are very rich in proline and include short tracts of polyproline, polyglycine, and charged amino acids. In addition, these proteins contain several unrelated families of similar repeated segments. BAT2 and BAT3 are similar to other proteins with large proline-rich domains, such as some nuclear proteins, collagens, elastin, and synapsin. BAT2 also contains four Arg-Gly-Asp (RGD) motifs typical of the integrin receptor family.

Amino Acid Sequence↗
PubMed1989

Antifertility effect of Piper betle Linn. extract on ovary and testis of albino rats.

Chronic administration (sc) of the extract of the stalk of P. betle at 30 mg/kg body weight daily for 21 days produced significant decrease in oestrogen and androgen dependent target organ weights along with increase in cholesterol in adrenal, ovary and testis. Acid and alkaline phosphatase activities in serum, liver and kidney did not exhibit any toxic effect. There was marked change in morphology of testis and ovary. Vaginal smear showed prolonged dioestrus in treated female. The treated male showed decreased number and motility of sperm. Both male and female remained infertile after treatment suggesting antifertility activity of the extract on both sexes of albino rats.

Animals↗
PubMed1983

A lymphocyte-specific cellular enhancer is located downstream of the joining region in immunoglobulin heavy chain genes.

Transcriptional enhancers, originally discovered in viral genomes, are short, cis-acting, regulatory sequences that strongly stimulate transcription from promoters of nearby genes. We demonstrate the existence of an enhancer within a mouse immunoglobulin heavy chain gene. A DNA fragment located between the joining region and the switch recombination region in the intron upstream of the immunoglobulin mu constant region has been linked, in both orientations, to genes coding for rabbit beta-globin or SV40 T antigen. This element enhances the number of correct beta-globin gene transcripts by at least two orders of magnitude and also stimulates production of T antigen. It acts from several hundred to several thousand base pairs up or downstream of a promoter without amplifying template copy number. Of the various cell lines tested, the immunoglobulin gene enhancer functions only in lymphocyte-derived (myeloma) cells. We propose that this tissue-specific enhancer contributes to the activation of somatically rearranged immunoglobulin variable region genes and possibly to abnormal expression of other genes (e.g. c-myc) that become translocated to its domain of influence.

Animals↗
PubMed1981

Expression of a beta-globin gene is enhanced by remote SV40 DNA sequences.

We have studied the transient expression of a cloned rabbit hemoglobin beta 1 gene after its introduction into HeLa cells. Two and one-half days after transfection using the calcium phosphate technique we extracted RNA from the entire cell population and analyzed it by the S1 nuclease hybridization assay. Transcripts were barely detectable when beta-globin gene-plasmid recombinants were used. However, 200 times more beta-globin gene transcripts were found when the beta-globin gene recombinants also contained SV40 DNA, and 90% of these transcripts (about 1000 per cell) had the same 5' end as authentic rabbit globin mRNA. In the latter case, abundant production of beta-globin protein was readily detected in a fraction of transfected cells by immunofluorescent staining. Enhancement of globin gene expression was dependent on SV40 sequences acting in cis, but independent of the viral origin of DNA replication. The enhancing activity was associated with the 72 bp repeated sequence element located at the beginning of the viral late gene region. Viral DNA fragments containing the transcriptional enhancer element could act in either orientation at many positions, including 1400 bp upstream or 3300 bp downstream from the transcription initiation site of the rabbit beta-globin gene. These studies define a class of DNA elements with a mode of action that has not been heretofore described. The activation of genes by specific enhancer elements seems to be a widespread mechanism that may be used for the regulation of gene expression.

Animals↗
PubMed1980

Mouse rDNA nontranscribed spacer sequences are found flanking immunoglobulin CH genes and elsewhere throughout the genome.

When a cloned 6 kb Eco RI-Sal I fragement of mouse ribosomal gene nontranscribed spacer DNA (rDNA NTS) was used to screen a BALB/c mouse gene library, 25% of the recombinant phage hybridized with it. In situ hybridization experiments and characterization of 12 clones selected using this probe supported the idea that sequences homologous to this rDNA NTS region are scattered throughout the genome. Subsequently, sequences homologous to mouse rDNA NTS were found flanking mouse mu, alpha and gamma 2b immunoglobulin CH genes. One region was localized 3' to the mu coding sequence, an area which has been identified as an intervening sequence between the secreted C mu heavy chain terminus and the C terminal portion of the membrane-bound C mu heavy chain.

Animals↗