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Biomedical subjects

M C Smith

Publications and source records attributed to M C Smith.

At least 199 records · Page 11Linked to original sources
PubMed1989

Streptomyces griseus streptomycin phosphotransferase: expression of its gene in Escherichia coli and sequence homology with other antibiotic phosphotransferases and with eukaryotic protein kinases.

The aphD gene of Streptomyces griseus, encoding a streptomycin 6-phosphotransferase (SPH), was sub-cloned in the pBR322-based expression vector pRK9 (which contains the Serratia marcescens trp promoter) with selection for expression of streptomycin resistance in Escherichia coli. Two hybrid plasmids, pCKL631 and pCKL711, were isolated which conferred resistance. Both contained a approximately 2 kbp fragment already suspected to include aphD. The properties of in vitro deletion derivatives of these plasmids were consistent with the presumed location of aphD. In vitro deletion of a sequence including most of the trp promoter largely, but not quite completely, abolished the ability of the plasmid to confer streptomycin resistance, confirming that expression was indeed principally from the trp promoter. A polypeptide of approximately 34.5 kDa was present in minicells containing plasmids that conferred streptomycin resistance, but was absent when the plasmids contained in vitro deletions removing streptomycin resistance. Part of the fragment was sequenced and an open reading frame corresponding to aphD identified. A computer-assisted comparison of the deduced SPH sequence with those of other antibiotic phosphotransferases suggested a common structure A-B-C-D-E, where B and D were conserved between all sequences compared while A, C and E divided between the streptomycin and hygromycin B phosphotransferases on one hand and kanamycin/neomycin ones on the other. A composite sequence data base was searched for homologues to consensus matrices constructed from five approximately 12-residue subsequences within blocks B and D. For one subsequence, corresponding to the N-terminal portion of block D, those sequences from the database that yielded the highest homology scores comprised almost entirely either antibiotic phosphotransferases or eukaryotic protein kinases. Possible evolutionary implications of this homology, previously described by other groups, are discussed.

Amino Acid Sequence↗
PubMed1989

Sequences required for regulation of arginine biosynthesis promoters are conserved between Bacillus subtilis and Escherichia coli.

The region required for regulation of a previously characterized arginine-regulatable promoter upstream from the argC gene in the argCAEBD-cpa-argF cluster of Bacillus subtilis was defined by integration of argC-lacZ translational fusions into the chromosome at a site distant from the arginine loci. Some sequence similarity was detected between the argC regulatory region and the well-characterized Escherichia coli arginine operators (ARG boxes). This similarity was shown to be functional in vivo in that the B. subtilis repressor regulated the E. coli arginine genes, but the E. coli repressor, even when encoded by a multicopy plasmid, could not repress the B. subtilis argC promoter. In vitro binding studies using purified repressors on DNA fragments encoding operators from both E. coli and B. subtilis demonstrated interactions by both proteins.

Arginine↗
PubMed1989

Recombinant DNA-derived human insulin-like growth factor II (hIGF-II) stimulates growth in hypophysectomized rats.

Sustained subcutaneous administration of recombinant DNA-derived insulin-like growth factor II to immature female hypophysectomized rats stimulated significant increases in body weight gain, tibial epiphyseal cartilage width, femur hydroxyproline concentrations and a significant decrease in serum urea nitrogen concentrations. Recombinant DNA-derived human growth hormone (Humatrope), administered in the same manner produced similar biological effects. The data support the contention that hIGF-II has anabolic effects when administered to hypophysectomized rats and may be a locally acting mediator of pituitary hormone actions.

Animals↗
PubMed1988

The arginine repressor is essential for plasmid-stabilizing site-specific recombination at the ColE1 cer locus.

The heritable stability in Escherichia coli of the multicopy plasmid ColE1 and its natural relatives requires that the plasmids be maintained in the monomeric state. Plasmid multimers, that arise through recA-dependent homologous recombination, are normally converted to monomers by a site-specific recombination system that acts at a specific plasmid site (cer in ColE1). No plasmid functions that act at this site have been identified. In contrast, two unlinked E.coli genes that encode functions required for cer-mediated site-specific recombination have been identified. Here we describe the isolation and characterization of one such gene (xerA) and show it to be identical to the gene encoding the repressor of the arginine biosynthetic genes (argR). The argR protein binds to cer DNA both in vivo and in vitro in the presence of arginine. We believe this binding is required to generate a higher order protein-DNA complex within the recombinational synapse. The argR gene of Bacillus subtilis complements an E.coli argR deficiency for cer-mediated recombination despite the two proteins having only 27% amino acid identity.

Amino Acid Sequence↗
PubMed1988

Bar suture (toggle pin) vs open surgical abomasopexy for treatment of left displaced abomasum in dairy cattle.

Fifty-nine dairy cows with left displacement of the abomasum were randomly assigned to receive 1 of 2 treatments. Twenty-eight were treated by right paramedian abomasopexy via laparotomy, and 31 were treated by percutaneous fixation of the abomasum, using the bar suture or toggle pin technique. Comparisons of the 2 groups, at 4 follow-up examinations, yielded no significant differences in return to normal milk production, return to normal feed intake, mortality, culling rate, tissue reaction at the surgical site, or redisplacement up to 60 days into the subsequent lactation.

Abomasum↗
PubMed1988

Autoradiographic localization of insulin-like growth factor II receptors in cerebellar cortex of weaver and Purkinje cell degeneration mutant mice.

Autoradiography was used to visualize insulin-like growth factor II (IGF-II) receptors in the cerebellar cortex of weaver and Purkinje cell degeneration (pcd) mice. These mutants were selected for their respective absence of granule or Purkinje cells. Histological preparations confirmed a severe loss of granule cells in the cerebella of weaver mutants and an absence of Purkinje cells in those of pcd mutants. Autoradiographs showed specific IGF-II binding to the granule cell layer of the cerebellar cortex in control mice, and in pcd mutants. No specific [125I]human IGF-II binding was observed in the cerebellar cortex of weaver mutants. These studies suggest that specific IGF-II receptor sites are located on the granule cells of the cerebellum.

Animals↗
PubMed1988

Hyperadrenocorticism in cats: seven cases (1978-1987).

Hyperadrenocorticism was diagnosed in 7 cats with concurrent diabetes mellitus. Four cats had pituitary adenoma with bilateral adrenocortical hyperplasia, 1 cat had pituitary carcinoma with bilateral adrenocortical hyperplasia, 1 cat had adrenocortical carcinoma, and 1 cat had adrenocortical adenoma of the left adrenal gland. One year later, adrenocortical adenoma involving the right adrenal gland also was diagnosed in this cat. Clinical signs included polyuria and polydipsia (n = 7), development of pot-bellied appearance (n = 5), dermatologic alterations (n = 5), lethargy (n = 3), weight loss (n = 3), dyspnea/panting (n = 2), and recurrent bacterial infections (n = 2). In 6 cats, the diagnosis of hyperadrenocorticism was established before death on the basis of results of the ACTH stimulation test (n = 3) and the dexamethasone screening test (n = 5). Pituitary-dependent hyperadrenocorticism was differentiated from adrenocortical neoplasia on the basis of results of the dexamethasone suppression test (n = 4), endogenous ACTH concentration (n = 3), results of abdominal radiography and ultrasonography (n = 3), and exploratory celiotomy (n = 1). Four cats died or were euthanatized without treatment attempts. Treatment with mitotane followed by 60Co teletherapy was ineffective in one cat with pituitary adenoma. One cat with pituitary carcinoma died one week after bilateral adrenalectomy. Bilateral adrenocortical adenomas were removed surgically in the affected cat.

Adenoma↗
PubMed1988

Effects of infection with caprine arthritis-encephalitis virus on milk production in goats.

A recently assembled commercial herd of Alpine goats was studied. Milk production criteria--305-day milk production (M), butter fat content (BF), and solids nonfat content (SNF)--and somatic cell counts (linear score) were monitored by Dairy Herd Improvement Association test records. Milk samples from all milking goats in the herd were obtained for bacteriologic culture for mastitis organisms on 2 occasions; the infection rate ascribed to major pathogens was 3%. In November 1985, serum specimens were obtained from 154 does in first lactation. Of these, 56 (36%) were seropositive for caprine arthritis-encephalitis (CAE) antibodies by agar gel immunodiffusion (AGID), 91 (59%) were seronegative, and serotest results for 7 (5%) were inconclusive. In December, 80 seronegative and 48 seropositive goats remained in the herd and had 305-day projections available. The median production values for seronegative goats (1,539.5 lb of M, 52 lb of BF, 46 lb of SNF) were higher than those for seropositive goats (1,446 lb of M, 45 lb of BF, 44.5 lb of SNF), but this difference was only significant (t test, P less than 0.05) for BF. Does were ranked by a formula that combined M, BF, and SNF, with a desired minimal daily herd average of 5 lb of M, 3% BF, and 3% SNF. A decision was made not to keep offspring from does of the lowest quartile before CAE test results were obtained. This group consisted of 13 of the 80 (16%) seronegative goats and 18 of the 48 (38%) seropositive goats. Thus, a positive CAE test result by AGID was associated (chi 2, P less than 0.01) with poor production.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Chelating peptide-immobilized metal ion affinity chromatography. A new concept in affinity chromatography for recombinant proteins.

We report our experimental results supporting the hypothesis that a specific metal-chelating peptide (CP) on the NH2 terminus of a protein can be used to purify that protein using immobilized metal ion affinity chromatography (IMAC). The potential utility of this approach resides with recombinant proteins since the nucleotide sequence that codes for the protein can be extended to include codons for the chelating peptide and thereby generate the gene for a chimeric CP-protein that can be cloned, expressed, and affinity-purified with immobilized metal ions. The chelating peptide purification handle could then be removed chemically or enzymatically after purification has been achieved to generate a protein with the natural amino acid sequence. The feasibility of using a chelating peptide as a purification handle has been demonstrated using a leuteinizing hormone-releasing hormone (LHRH) analog, 2-10 LHRH, which contains the previously identified chelating peptide, His-Trp, on the NH2 terminus. 2-10 LHRH had a high affinity for a Ni(II) IMAC column due to the NH2-terminal dipeptide sequence His-Trp, forming a coordination complex with Ni(II), whereas the controls, 3-10 LHRH and 4-10 LHRH, lacking the CP sequence, did not bind. Furthermore, 2-10 LHRH could be purified from a mixture of histidine-containing peptides on a Ni(II) IMAC column in one step. His-Trp proinsulin was used as a model of a recombinant CP-protein. The S-sulfonates of His-Trp-proinsulin and proinsulin were isolated from Escherichia coli engineered to overproduce these proteins as trpLE' fusion proteins. His-Trp-proinsulin(SSO3-)6 had a higher affinity for immobilized Ni(II) than proinsulin (SSO3-)6. Both proteins were eluted by decreasing the pH or by introducing a displacing ligand into the buffer. Ni(II) eluted from the column with much higher concentrations of displacing ligand than the proteins.

Amino Acid Sequence↗
PubMed1988

Cerebral coenurosis in a cat.

Coenurus serialis, the intermediate stage of Taenia serialis, was the cause of progressive, fatal, intracranial disease in a 5-year-old cat. X-Ray computed tomographic findings were identical to those associated with intracranial parasitic cysts in people, in whom x-ray computed tomographic features are considered pathognomonic and superior to those of other diagnostic methods. The presumed source of the coenurus was the owner's dog.

Animals↗
PubMed1988

Pharmacists' views about health promotion practices.

A mail survey was conducted among a sample of 1,115 Mississippi pharmacists. The survey instrument included 25 statements concerning personal health practices which the respondents were asked to rate, using a Likert scale, on their importance to the health of an average person. Only one item, "Avoidance of alcohol altogether," received a mean score in the unimportant range. The item rated highest was "Taking prescriptions exactly as prescribed." Paradoxical attitudes concerning cigarettes and vitamins are discussed.

Attitude of Health Personnel↗
PubMed1988

Correlation of the sinoscopic appearance of the maxillary antrum with histological and bacteriological findings.

Assessment of the maxillary antral mucosa in chronic sinusitis prior to surgery is notoriously difficult. Sinoscopy using a Hopkin's rod system is proving increasingly popular. The accuracy of diagnosis of mucosal disease by this means in 26 antra is here correlated with histological evidence of inflammation and bacteriological evidence of infection in antral mucosal biopsies. It is shown that the surgeon's assessment of the mucosal appearance correlates well with the histology and bacterial culture. Absence of mucopus or bacterial growth on culture did not indicate absence of disease.

Adolescent↗