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C L Smith

Publications and source records attributed to C L Smith.

At least 217 records · Page 12Linked to original sources
PubMed1991

Ontogeny of corticosteroid-binding globulin biosynthesis in the rat.

In plasma, glucocorticoids are transported by corticosteroid-binding globulin (CBG), which is synthesized primarily in the liver. Plasma levels of maternal and fetal CBG fluctuate during gestation, and this may be due to changes in the biosynthesis and/or clearance of the protein. We have, therefore, studied the ontogeny of CBG biosynthesis in the rat by using a solution hybridization assay to measure hepatic CBG mRNA levels. The results indicate that the concentration of CBG mRNA is exceptionally high in 15-day-old fetal livers (55.1 pg CBG mRNA/micrograms total RNA), but declines to very low levels at birth (day 21). During the same period, CBG mRNA levels in maternal livers remained relatively constant (18.9-23.1 pg CBG mRNA/micrograms total RNA). Hepatic CBG mRNA levels were barely detectable 1 week after birth, and a sex difference was apparent by 2 weeks of age, with higher levels in female livers. Although adult CBG mRNA levels were attained by 3 weeks of age, serum CBG concentrations did not reach adult values for an additional 3 weeks. To determine whether age-related differences in the clearance of CBG are responsible for this, CBG from infant or adult animals was radiolabeled and administered iv to infant and adult rats. When this was done, the half-life of CBG in infants (approximately 6.9 h) was consistently less than that in adults (approximately 14.5 h) regardless of the source of the labeled CBG, and we conclude that variations in CBG biosynthesis and clearance may influence glucocorticoid action during fetal and postnatal development.

Aging↗
PubMed1991

Overexpression of the human vitamin D3 receptor in mammalian cells using recombinant adenovirus vectors.

The human vitamin D3 receptor (hVDR) cDNA was cloned into the E1 region of the adenovirus genome to generate recombinant viruses which were used to infect 293 (adenovirus-transformed human fetal kidney) cells. High salt extracts from cells infected with the recombinant viruses were subjected to immunoblot analysis using a monoclonal antibody to chicken VDR and were shown to contain large quantities of a protein of approximately 50 kDa with a migration identical to that of the hVDR in T47D (human mammary adenocarcinoma) cells. Scatchard analysis showed that the infected cells express approximately 100-fold more receptor than T47D cells and that this receptor binds 1,25-dihydroxyvitamin D3 with high affinity. The overexpressed hVDR also binds to DNA-cellulose and is eluted with a KCl concentration similar to that determined for fully active endogenous VDR. Nuclear extracts from cells infected with the hVDR-expressing adenoviruses contain an activity that specifically binds an oligonucleotide with sequences from the rat osteocalcin vitamin D3 response element, as determined by gel mobility shift. This interaction can be inhibited by the presence of an anti-VDR antibody, but not by nonspecific immunoglobulins. We conclude, therefore, that the overexpressed receptor has the ligand- and DNA-binding characteristics defined for endogenous VDR and that adenoviruses can be used to efficiently express large quantities of functional hVDR in a human cell line. Finally, a second binding activity, specific for the vitamin D response element, but distinct from the VDR, has been identified in extracts from uninfected cells.

Adenoviruses, Human↗
PubMed1991

Mitogen induced proliferative responses of lymphocytes from spot (Leiostomus xanthurus) exposed to polycyclic aromatic hydrocarbon contaminated environments.

The marine fish spot, Leiostomus xanthurus, was collected from five sites in the lower Chesapeake Bay system representing a gradient of sediment polycyclic aromatic hydrocarbon (PAH) concentrations. The proliferative responses to mitogens by anterior kidney lymphocytes were assessed using [3H]-thymidine uptake by replicating DNA. The data shows two different mitogen-dependent lymphocytic responses as the sediment PAH levels increase at the sampling sites; a suppression of the response to the T cell mitogens, concanavalin A (Con A) and phytohemagglutinin, and a sharp augmentation of the response to B cell mitogen, lipopolysaccharide (LPS), as well as to poke weed mitogen and peanut agglutinin. The magnitude of the lymphoproliferative responses correlated strongly with the total sediment PAH concentrations (r2 greater than 0.8). A similar correlation was also observed with 15 selected individual PAH compounds regardless of their molecular weights. By maintaining the fish in clean York River water for up to 24 weeks, it was possible to reverse the augmented proliferative responses to LPS of fish from all sampling sites and to increase the reduced responses to Con A, in fish from three sites, and partially in two sites where sediments were highly contaminated with PAH. These results suggest that the proliferative responses of fish lymphocytes to mitogens may be a potentially sensitive biomarker of exposure to, and effects of xenobiotics.

Animals↗
PubMed1991

Software support for Huntingtons disease research.

Huntingtons disease (HD) is a hereditary disorder involving the central nervous system. Its effects are devastating, to the affected person as well as his family. The Department of Medical and Molecular Genetics at Indiana University (IU) plays an integral part in Huntingtons research by providing computerized repositories of HD family information for researchers and families. The National Huntingtons Disease Research Roster, founded in 1979 at IU, and the Huntingtons Disease in Venezuela Project database contain information that has proven to be invaluable in the worldwide field of HD research. This paper addresses the types of information stored in each database, the pedigree database program (MEGADATS) used to manage the data, and significant findings that have resulted from access to the data.

Algorithms↗
PubMed1990

Transcription regulates oxolinic acid-induced DNA gyrase cleavage at specific sites on the E. coli chromosome.

Prominent DNA gyrase-mediated cleavage sites, induced by oxolinic acid, occur at specific, but infrequent, locations on the Escherichia coli chromosome. These sites, which we call toposites, may represent high affinity DNA gyrase binding sites or may mark chromosomal regions that accumulate superhelical stress. Toposites are usually grouped in 5 to 10 kb clusters that are mostly 50 to 100 kb apart. The total number of clusters on the chromosome is between 50 and 100. The location of sites depends on the local sequence. The extent of DNA gyrase cleavage at toposites can be strongly modulated by transcription occurring at as far as 35 kb away.

Binding Sites↗
PubMed1990

Interaction between corticosteroid binding globulin and activated leukocytes in vitro.

The interaction between human corticosteroid binding globulin and activated leukocytes is restricted to the granulocyte population, and is characterized by specific proteolytic cleavage of corticosteroid binding globulin which markedly reduces its steroid binding activity. A direct interaction between corticosteroid binding globulin and the activated cells appears to enhance this event, and does not involve cellular internalization of corticosteroid binding globulin or its proteolytic degradation products, which resemble those obtained after incubation of corticosteroid binding globulin with neutrophil elastase. These data suggest that corticosteroid binding globulin interacts with elastase on the surface of activated neutrophils, and may promote glucocorticoid delivery to these cells during inflammation.

Blotting, Western↗
PubMed1990

Bone-marrow transplant from father to son and subsequent graft from son to father.

An 11-year-old boy with acute myeloblastic leukaemia in first remission received an allogeneic mismatched bone-marrow transplant (BMT) from his father in 1979; subsequent HLA typing showed that his haemopoietic system had been repopulated by the donor cells. In 1986 hypereosinophilic syndrome, secondary to a T-cell lymphocytic lymphoma, developed in the father, then aged 45 years. A full haematological remission was obtained by means of standard acute lymphoblastic leukaemia treatment. He then received melphalan, total body irradiation, and a BMT from his son. Graft-versus-host disease was transient in both patients, and father and son remain well and disease-free 20 months and 10 years, respectively, after BMT.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1990

Complete physical map of the WAGR region of 11p13 localizes a candidate Wilms' tumor gene.

A complete physical map of the 11p13 region containing the Wilms' tumor locus has been developed and used to localize a candidate Wilms' tumor gene. Our strategy to construct the map combined the use of pulsed-field gel electrophoresis and irradiation-reduced somatic cell hybrids. These hybrids, which contain limited segments of human chromosome 11 segregated from the remainder of the human genome, permit direct visualization of restriction fragments located in 11p13 using human interspersed repeated DNA sequences as hybridization probes. The physical map has provided a framework to identify the sites of genes responsible for the complex of disorders associated with hemizygous 11p13 deletion: Wilms' tumor, aniridia, genitourinary abnormalities, and mental retardation. The Wilms' tumor locus has been limited to a region of less than 345 kb, and a transcript with many of the characteristics expected for the Wilms' tumor gene has been localized to this region.

Cell Line↗
PubMed1990

The critical period for peripheral specification of dorsal root ganglion neurons is related to the period of sensory neurogenesis.

Thoracic sensory neurons in bullfrog tadpoles can be induced to form connections typical of brachial sensory neurons by transplanting thoracic ganglia to the branchial level at stages when some thoracic sensory neurons already have formed connections. In order to find out how many postmitotic sensory neurons survive transplantation, [3H]thymidine was administered to tadpoles in which thoracic ganglia were transplanted to the brachial level unilaterally at stages VII to IX. Between 16 and 37% of the neurons in transplanted ganglia were unlabeled, as compared to 46 to 60% in unoperated ganglia. Transplanted ganglia contained fewer unlabeled neurons than corresponding unoperated ganglia, indicating that transplantation caused degeneration of postmitotic neurons. Therefore, a large fraction of the neurons that formed connections typical of brachial sensory neurons probably differentiated while they were at the brachial level.

Animals↗
PubMed1990

YAC cloning of telomeres.

Human telomeres have been successfully cloned in Saccharomyces cerevisiae by complementing deficient yeast artificial chromosomes (YACs). This technique allows cloning of DNA sequences that can recognize particular chromosomal ends, and therefore facilitates the mapping of eukaryotic genomes. Although the biology of adopting foreign telomeres in yeast is not fully understood, the cloning system itself seems to be a useful tool for constructing telomeric DNA libraries from higher eukaryotes. Here we describe the techniques that are currently being used in cloning of telomeric DNA.

Chromosomes, Fungal↗
PubMed1990

Megabase scale restriction fragment length polymorphisms in the human major histocompatibility complex.

Pulsed-field gel electrophoresis of human peripheral blood lymphocyte DNA was used to ascertain the extent of megabase restriction fragment length variation in the HLA region of human chromosome 6 and to determine whether previously reported diversity was due to experimental variation or DNA polymorphism. Polymorphism was found to predominate in the vicinity of the class II DR, class III complement, and the class I A genes and to be limited or absent near the class II DP genes, the TNF genes, and the class I B and C genes. Thus, the MHC region is characterized by both fine and large-scale structural diversity.

Chromosome Mapping↗
PubMed1990

Role of complement receptors in opsonophagocytosis of group B streptococci by adult and neonatal neutrophils.

The role of complement receptors in bactericidal activity for types III and Ia group B streptococci (GBS) by adult or neonatal polymorphonuclear leukocytes (PMNL) was explored using polyclonal and monoclonal antibodies to complement receptors one (CR1) and three (CR3). In an opsonophagocytic assay, selective blockade of the CR3 sugar or lectin-like binding site on adult or neonatal PMNL effected a significant reduction in killing of both GBS serotypes that was more pronounced for type III. In contrast, blockade of the iC3b binding site effected greater inhibition of bactericidal activity for type Ia than for type III GBS. When both the CR3 sugar or lectin-like binding site and CR1 were blocked, inhibition was enhanced for type Ia GBS by adult PMNL and for both serotypes by neonatal PMNL. These results demonstrate a role for both CR1 and CR3 in the opsonophagocytosis of GBS. Possibly, differences in CR3 epitope utilization contribute to the differential virulence among GBS serotypes in neonates.

Adult↗
PubMed1990

Teicoplanin compared to flucloxacillin for antibiotic treatment of neutropenic patients.

Ninety-eight neutropenic patients were randomized to receive piperacillin and gentamicin in combination with either teicoplanin or flucloxacillin. Sixty-seven of these patients, most of whom had myeloma, were given this combination as prophylaxis 5 d after high dose chemotherapy, 35 receiving flucloxacillin and 32 receiving teicoplanin. Of 31 patients with leukaemia who were febrile and neutropenic following induction chemotherapy or bone marrow transplantation, 18 received flucloxacillin and 13 received teicoplanin. For those given flucloxacillin, the mean number of days to change of antibiotics was 7.8 in the prophylaxis group and 5.1 in the treatment group. In the teicoplanin arm, the mean number of days to change antibiotics was 6.8 in the prophylaxis group and 6.1 in the treatment group. Two patients in the flucloxacillin arm developed drug rashes. Four patients developed rigors after teicoplanin administration and one asthmatic became wheezy. One patient had a progressive rise in creatinine, but overall the patients having teicoplanin did not have any appreciable increase of renal toxicity compared to the flucloxacillin arm. Blood cultures were positive prior to commencement in the treatment group in nine patients, and during treatment in six patients. Organisms grown were Gram-positive in 14 patients. Teicoplanin appears to be as effective as flucloxacillin when each is used in combination with piperacillin and gentamicin in the treatment of neutropenic patients, with similar rates of toxicity.

Anti-Bacterial Agents↗
PubMed1990

Integration of bacteriophage lambda into the cryptic lambdoid prophages of Escherichia coli.

Bacteriophage lambda missing its chromosomal attachment site will integrate into recA+ Escherichia coli K-12 and C at the sites of cryptic prophages. The specific regions in which these recombination events occur were identified in both lambda and the bacterial chromosomes. A NotI restriction site on the prophage allowed its physical mapping. This allowed us to identify the locations of Rac, Qin, and Qsr' cryptic prophages on the NotI map of E. coli K-12 and, by analogy, to identify the cryptic prophage in E. coli C as Qin. No new cryptic prophages were detected in E. coli K-12.

Bacteriophage lambda↗
PubMed1990

A rapidly rearranging retrotransposon within the miniexon gene locus of Crithidia fasciculata.

The tandemly arrayed miniexon genes of the trypanosomatid Crithidia fasciculata are interrupted at specific sites by multiple copies of an inserted element. The element, termed Crithidia retrotransposable element 1 (CRE1), is flanked by 29-base-pair target site duplications and contains a long 3'-terminal poly(dA) stretch. A single 1,140-codon reading frame is similar in sequence to the integrase and reverse transcriptase regions of retroviral pol polyproteins. Cloned lines derived from a stock of C. fasciculata have unique arrangements of CRE1s. In different cloned lines, CRE1s, in association with miniexon genes, are located on multiple chromosomes. By examining the arrangement of CRE1s in subclones, we estimate that the element rearranges at a rate of ca. 1% per generation. These results indicate that the C. fasciculata miniexon locus is the target for a novel retrotransposon.

Amino Acid Sequence↗
PubMed1990

Spontaneous regression of hepatocellular carcinoma.

A 63 year old white woman presented with abdominal discomfort, anorexia, and weight loss. Investigations showed hepatocellular carcinoma with pulmonary metastases. The primary and secondary tumours resolved without specific treatment.

Carcinoma, Hepatocellular↗
PubMed1990

Sensitivity of erythrocytes to oxidant stress in uremia.

The erythrocytes from 19 chronic hemodialysis patients were examined for Heinz bodies and their sensitivity to oxidant stress. Heinz bodies were found in 63% of patients and an elevated level of oxidized hemoglobin in 36%. When exposed to acetylphenhydrazine oxidant stress, 84% had a normal response and 95% had stable reduced glutathione levels. Ascorbic-acid-induced oxidant stress was tolerated by 84%. The activities of enzymes associated with the hexose monophosphate shunt were examined and found to be intact. This study demonstrates an increased number of Heinz bodies in hemodialysis patients. However, this is not due to an increased sensitivity to oxidant stress. Other mechanisms must be sought to explain the presence of Heinz bodies in these patients.

Adult↗