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Biomedical subjects

K Ray

Publications and source records attributed to K Ray.

At least 73 records · Page 4Linked to original sources
PubMed1999

Cytological study of serous effusions with the aid of tumour markers.

Clinicocytological evaluation with the help of tumour markers was done in 25 cases presenting with serous effusions. The main aim was to differentiate between reactive mesothelial cells and malignant cells, type the tumour cells in effusions with the aid of tumour markers--carcino-embryonic antigen (CEA), epithelial membrane antigen (EMA), cytokeratin and vimentin. It was observed that immunocytochemistry has complemented conventional cytology in diagnosis of carcinoma specially in cases labelled as suspicious of malignancy. EMA was found to be the most reliable epithelial marker and very useful in differentiating carcinoma cells from reactive mesothelial cells.

Abdominal Neoplasms↗
PubMed1999

Assessment of the need for a training course in rational use of drugs: a cross-sectional pilot study.

Rational use of drugs means need-based use of them keeping in mind the pathological status, therapeutic indices, drugs interactions and adverse drug reactions. Lacunae in the existing undergraduate curriculum cause irrational use of drugs. The present study was undertaken among 2,200 fresh medical graduates from all over the country with a list of questionnaire distributed among them and analysing the answers. The aim was to ascertain the adequacy of present undergraduate curriculum on pharmacology in equipping the doctors on rational use of drugs and to assess the need and feasibility of Refresher's course. More than half (55%) replied prescriptions were not truly rational. Ninety-eight per cent opened Refresher's course is beneficial in rational prescribing. This cross-sectional survey could provide a glimpse of existing undergraduate pharmacology curriculum and its impact on rational prescribing practice. The Refresher's course in the early internship period involving the clinical departments and department of pharmacology is suggested.

Cross-Sectional Studies↗
PubMed1999

Surrogate endpoints: do they really contribute in therapeutic decision making?

Surrogate endpoints are substitutes for the true endpoints and measured in any clinical research to relate in some way to the outcome of primary interest. Inappropriate selection of surrogate markers may lead to controversies during clinical trials or therapeutic interventions. Use of surrogate markers depends upon thorough understanding of the pathophysiology of the disease and pharmacology of drugs. Results obtained with surrogates should be regarded as preliminary and necessitates definitive studies.

Clinical Trials as Topic↗
PubMed1998

Identification of the sites of N-linked glycosylation on the human calcium receptor and assessment of their role in cell surface expression and signal transduction.

The human calcium receptor (hCaR) is a G-protein-coupled receptor containing 11 potential N-linked glycosylation sites in the large extracellular domain. The number of potential N-linked glycosylation sites actually modified, and the effect on cell surface expression and signal transduction of blocking glycosylation at these sites, was examined by site-directed mutagenesis. Asparagine residues of the consensus sequences (Asn-Xaa-Ser/Thr) for N-linked glycosylation were mutated to glutamine individually and in various combinations to disrupt the potential N-linked glycosylation sites in the context of the full-length receptor. The cDNA constructs were transiently transfected into HEK-293 cells lacking endogeneous hCaR, and expressed receptors were analyzed by mobility differences on immunoblots, glycosidase digestion, intact cell enzyme-linked immunoassay, and extracellular calcium-stimulated phosphoinositide hydrolysis assay. Immunoblot analyses and glycosidase digestion studies of the wild type versus mutant receptors demonstrate that, of the 11 potential sites for N-linked glycosylation, eight sites (Asn-90, -130, -261, -287, -446, -468, -488, and -541) are glycosylated; the three remaining sites (Asn-386, -400, and -594) may not be efficiently glycosylated in the native receptor. Sequential mutagenesis of multiple N-linked glycosylation sites and analyses by immunoblotting, immunofluorescence, biotinylation of cell surface proteins, and intact cell enzyme-linked immunoassay indicated that disruption of as few as three glycosylation sites impairs proper processing and expression of the receptor at the cell surface. Disruption of five glycosylation sites reduced cell surface expression by 50-90% depending on which five sites were disrupted. Phosphoinositide hydrolysis assay results for various glycosylation-defective mutant receptors in general correlated well with the level of cell surface expression. Our results demonstrate that among 11 potential N-linked glycosylation sites on the hCaR, eight sites are actually utilized; glycosylation of at least three sites is critical for cell surface expression of the receptor, but glycosylation does not appear to be critical for signal transduction.

Amino Acid Substitution↗
PubMed1998

Congenital stationary night blindness in the dog: common mutation in the RPE65 gene indicates founder effect.

PURPOSE: To clone and characterize the canine RPE65 cDNA from normal dog, examine for mutations, and establish if the mutation identified in Swedish briard dogs with retinal dystrophy is present in dogs of the same breed that originated from the United States and other countries, and are affected with congenital stationary night blindness. METHODS: Fifteen briard dogs were studied, of which 10 were affected with csnb, and five were clinically normal. In addition, we tested samples from four Swedish dogs, and samples from a briard affected with progressive retinal atrophy. RPE65 cDNA was cloned a from retinal cDNA library by PCR, and from canine retina by RT-PCR. ERG and morphology were used to characterize csnb. RESULTS: The normal RPE65 cDNA spans 1724 nucleotides (GenBank accession number AF084537), and includes 1602 nucleotides of coding sequence; the deduced amino acid sequence shares 98%, 97%, and 93% identity with homologous human, bovine, and rat sequences, respectively. A homozygous four nucleotide (AAGA) deletion, representing nucleotides 487-490 of wildtype RPE65 sequence, was found only in csnb and retinal dystrophy affected dogs; heterozygous animals had normal and mutant alleles. The mutation produces a frameshift, causing a deduced mistranslation with a premature stop codon. The mutation causes retinal dysfunction and RPE accumulation of lipid vacuoles. CONCLUSIONS: Identification of the same mutation in csnb and retinal dystrophy confirms the molecular identity of the two disorders. A common mutation in dogs derived from different countries suggests a founder effect causing the propagation of a common mutant allele in the population at risk.

Amino Acid Sequence↗
PubMed1998

Vitamin D-binding protein gene transcription is regulated by the relative abundance of hepatocyte nuclear factors 1alpha and 1beta.

Vitamin D-binding protein (DBP)/Gc-globulin, the major carrier of vitamin D and its metabolites in blood, is synthesized predominantly in the liver in a developmentally regulated fashion. By transient transfection analysis, we identified three regions in the 5'-flanking region of the rat DBP gene, segments F-2, B, and A, that contain tissue-specific transcriptional determinants. Gel mobility shift and DNase I footprinting analyses showed that all three regions contained binding sites for the hepatocyte nuclear factor 1 (HNF1), a transcriptional regulator composed of HNF1alpha and HNF1beta hetero- and homodimers. The activity of the most proximal segment A (coordinates -141 to -43) was DBP promoter-specific, position-dependent, and positively controlled by HNF1alpha. In contrast, the two more distal determinants (segments F-2 and B; coordinates -1844 to -1621 and -254 to -140, respectively) acted as classical enhancers in transfected hepatocyte-derived HepG2 cells; their activities were promoter- and orientation-independent, and disruption of their respective HNF1-binding sites resulted in marked loss of DBP gene expression. Remarkably, the activities of these two distal elements depended upon the relative levels of HNF1alpha and HNF1beta; HNF1alpha had a major stimulatory effect, whereas HNF1beta acted as a trans-dominant inhibitor of HNF1alpha-mediated enhancer activity. These results suggested that the net expression of the DBP gene reflected a balance between the two major HNF1 species; the relative abundance of HNF1alpha and HNF1beta proteins in a cell may thus play a critical role in determining the pattern of gene expression.

Animals↗
PubMed1998

Mutational analysis of the cysteines in the extracellular domain of the human Ca2+ receptor: effects on cell surface expression, dimerization and signal transduction.

Mammalian calcium receptors (CaRs) share with the metabotropic glutamate receptors (mGluRs) the relative positions of 16 cysteine residues in the amino-terminal extracellular domain. To investigate the role of these cysteines, a series of mutants in the extracellular domain of the human CaR was prepared in which each of these 16 cysteine residues and three others not conserved in the mGluRs were replaced by serines. Wild-type and mutant CaR cDNAs were expressed in HEK-293 cells, and evaluated for expression and response to extracellular calcium. Mutation of three non-conserved cysteines and of two conserved cysteines produced proteins with near wild-type phenotype. In contrast, mutation of the other conserved cysteines gave proteins that showed drastic reduction in cell surface expression and/or failed to respond to calcium. We identified 14 cysteines essential for proper trafficking and function of the receptor, two of which may be involved in formation of a disulfide-linked dimer.

Amino Acid Substitution↗
PubMed1998

Characterization of canine photoreceptor phosducin cDNA and identification of a sequence variant in dogs with photoreceptor dysplasia.

Photoreceptor dysplasia (pd) is an autosomal recessive disease of miniature schnauzer dogs causing retinal degeneration. The disease is a homologue of retinitis pigmentosa, a group of genetically heterogeneous diseases, causing blindness in humans. A subtraction library was prepared from retinas of pd affected and age-matched normal control dogs to isolate de novo candidate genes for further examination. From the subtraction library, cDNA for phosducin (PDC), a member of the phototransduction pathway, was isolated as a transcript expressed at a higher level in the affected retina. First, the normal canine PDC cDNA was characterized to evaluate the PDC gene in the pd-affected retina. The characterized region of normal PDC cDNA spans 1258 nucleotides (nt) that include 738 nt of coding sequence predicted to encode a protein (Mr=28 209) of 245 amino acids (aa). Over the coding region, PDC shares 86-95% nt sequence identity and 90-95% identity in the deduced aa sequence with homologous mammalian sequences. A major transcript (1.9 kb) was observed only in retina by Northern analysis, but low levels of transcript were detected in brain, liver and kidney by reverse transcription and polymerase chain reaction. Retinal immunocytochemistry showed that PDC was detected only in rod photoreceptors, mainly in the inner segment and perinuclear region. By Northern blot analysis, increased PDC expression was observed in pre-degenerate affected retina relative to the age-matched normal. In pd- affected miniature schnauzer pedigree, a missense mutation was detected in codon 82 (CGA to GGA) that would create a non-conservative substitution (Arg to Gly) in close vicinity to the residue (Glu 85) which directly interacts with the betagamma-subunits of transducin. Only pd-affected dogs were found to be homozygous for the mutant allele, and none among 48 dogs tested from 20 other dog breeds had this allele, suggesting that the mutation could be causally associated with pd in miniature schnauzers. However, since some affected dogs are heterozygous for the mutant allele, and some are homozygous for the wild-type allele, this putative PDC missense mutation, if it is indeed a disease causing mutation, does not account entirely for the genetics of inherited retinal degeneration in the miniature schnauzer breed.

Amino Acid Sequence↗
PubMed1998

A marine natural product inhibitor of kinesin motors.

Members of the kinesin superfamily of motor proteins are essential for mitotic and meiotic spindle organization, chromosome segregation, organelle and vesicle transport, and many other processes that require microtubule-based transport. A compound, adociasulfate-2, was isolated from a marine sponge, Haliclona (also known as Adocia) species, that inhibited kinesin activity by targeting its motor domain and mimicking the activity of the microtubule. Thus, the kinesin-microtubule interaction site could be a useful target for small molecule modulators, and adociasulfate-2 should serve as an archetype for specific inhibitors of kinesin functions.

Adenosine Diphosphate↗
PubMed1998

Linkage analysis and comparative mapping of canine progressive rod-cone degeneration (prcd) establishes potential locus homology with retinitis pigmentosa (RP17) in humans.

Progressive rod-cone degeneration (prcd) is the most widespread hereditary retinal disease leading to blindness in dogs and phenotypically is the canine counterpart of retinitis pigmentosa (RP) in humans. In previous efforts to identify the genetic locus for prcd, the canine homologs for many of the genes causally associated with RP in humans, such as RHO, PDE6B, and RDS/peripherin, have been excluded. In parallel with a recent undertaking to establish a framework map of the canine genome, multiple prcd-informative pedigrees have been typed with a panel of more than 100 anchor loci and microsatellite-based markers. Identification of a linkage group flanking prcd ([TK1, GALK1, prcd]-[MYL4, C09.173, C09.2263]-RARA-C09.250-C09.474-NF1) localizes prcd close to the centromeric end of canine chromosome 9 (CFA9), and excludes RARA as a candidate gene. The conserved synteny of this region of CFA9 and distal human chromosome 17q establishes the potential locus homology of prcd in the dog with RP17, a human retinitis pigmentosa locus for which no gene has yet been identified. Assignment of the prcd disease locus to an identified canine autosome represents a powerful application of the developing canine linkage map in medical genetics. The usefulness of this approach is further demonstrated by identification of the correspondence of the prcd interval to homologous human and mouse chromosomal regions. The rapid progress that is now occurring in the field of canine genetics will expedite the identification of the genes underlying many of the inherited traits and diseases that make the dog a unique asset for the study of mammalian traits.

Animals↗
PubMed1998

Identification of a RAPD marker linked to progressive rod-cone degeneration in dogs.

Random amplified polymorphic DNA (RAPD) analysis has been used widely in plant and fungi for identification of markers linked to genetic traits and mapping, but its use is limited to identification of intra- and inter-species difference in domestic mammals. We report here identification of a RAPD-derived marker linked to progressive rod-cone degeneration (prcd), an inherited autosomal recessive retinal disease of dogs. A total of 400 standard 10-mer primers were used for amplification by use of DNA samples from normal (+/+) and affected (prcd/prcd) dogs. A single primer was identified which amplified a 1.5-kb DNA fragment only from normal dogs. PCR with longer primers designed from the sequence-characterized amplified region of the 1.5-kb DNA fragment identified a co-dominant multi-allelic polymorphism in the prcd-informative pedigree. Three recombinants were identified among 34 informative offsprings, yielding a LOD score of 5.568 at theta = 0.091. This marker was mapped to two canine-rodent hybrid cell lines in which two genes (canine homologues of human breast cancer 1 susceptibility gene, and cGMP phosphodiesterase gamma-subunit gene), and three anonymous microsatellites have been identified. This is the first reported identification of a RAPD-derived marker with multiple alleles linked to a mammalian disease locus.

Alleles↗
PubMed1998

A highly conserved microsatellite in the dystrophin gene of diverse mammalian species.

The presence of a CA repeat within the 3'-untranslated region (UTR) of the dystrophin gene has been reported previously in several species. Because microsatellites showing high cross-species homology can be conveniently used as markers in those species for which detailed linkage maps have not yet been developed, we evaluated whether the CA repeat could be amplified from a wide variety of mammalian species. Using a single pair of canine-specific oligonucleotide primers, we successfully amplified the 3'-UTR from 18 different carnivore and six additional species (human, chimpanzee, goat, cow, rabbit and mouse) and show conservation of the CA repeat in the dystrophin gene from a wide range of evolutionarily diverse mammalian species.

Adenine↗
PubMed1998

Deficiency of cytosolic arylamine N-acetylation in the domestic cat and wild felids caused by the presence of a single NAT1-like gene.

The purpose of this study was to determine the molecular basis for a relative deficiency in the cat of cytosolic arylamine N-acetyltransferase (NAT), an enzyme family that is important in the metabolism of xenobiotics and that normally consists of at least two related enzymes, NAT1 and NAT2. N-acetyltransferase in feline liver showed high affinity (mean Km = 2.1 microM) for p-aminobenzoic acid, an NAT1 selective substrate in humans and rabbits, but showed a very poor affinity (mean Km > 10 mM) for sulfamethazine, an NAT2 selective substrate in humans and rabbits. Immunoreactive N-acetyltransferase was detected in feline liver, bladder and colon using an NAT1-specific antipeptide antibody, but was not detected in any tissues using an NAT2-specific antibody. Southern blot analysis of genomic DNA demonstrated a single band in domestic cats using each of six restriction digests; single bands were also found on Southern blot analysis of six wild felids. The deduced amino acid sequence of the central portion of feline N-acetyltransferase, obtained by polymerase chain reaction amplification in both domestic cats and seven wild felids (lion, tiger, lynx, snow leopard, bobcat, Asian leopard cat and cheetah), contained three residues, Phe125, Arg127, and Tyr129, which determine NAT1-like substrate specificity in humans. These results support the conclusion that cytosolic arylamine N-acetylation activity is low in the cat because of the presence of a single N-acetyltransferase that has substrate specificity, immunogenicity and sequence characteristics similar to human NAT1, and that the unusual presence of only a single N-acetyltransferase gene appears to be a family wide trait shared by other felids.

Acetylation↗
PubMed1998

Process and outcome of a visitation to a Central-European dental school.

The Advisory Committee on the Training of Dental Practitioners of the EU (ACTDP) in order to ensure a comparably demanding standard in dental education, recommended in 1986 a self-assessment system, and visitations to dental training establishments. After some visitations in EU member countries, a visit was organized to the Dental Faculty, Semmelweis University of Medicine, Budapest, at the request of the Hungarian institution. The completion of the self-assessment questionnaire, and the organization of the visit occurred according to the general guidelines. The visit took place in September 1994, by a team consisting of 4 members. The results of the 3-day visit, and recommendations of the visitation team were presented in a written report, approved by the leaders of the Hungarian Faculty. As a consequence, a curriculum reform was elaborated at the visited Dental School, following the guidelines given by the visitation team, approved by the Faculty in 1996. Summarizing the outcome of the visit, this seemed to be very useful for the visited Dental Faculty, and helped to overcome difficulties in establishing a new curriculum, with better harmonization to EU standards. However, benefits may also derive from these visits for EU countries as well, for convergence in oral health education is of mutual importance for both sides.

European Union↗