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Biomedical subjects

M C Smith

Publications and source records attributed to M C Smith.

At least 253 records · Page 14Linked to original sources
PubMed1985

Comparative efficacy and selectivity of some nucleoside analogs against Epstein-Barr virus.

The effects of (2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-iodocytosine (FIAC), 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-methyluridine (FMAU), 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-iodouridine (FIAU), (E)-5-(2-bromovinyl)-2'-deoxyuridine (BVdU), and 9-(1,3-dihydroxy-2-propoxymethyl)guanine (DHPG or BW B759U) on the replication of Epstein-Barr virus (EBV) in vitro were evaluated and compared with that of acyclovir (ACV). The relative potencies of these drugs, on the basis of anti-EBV activity, were: FIAC = FIAU greater than FMAU greater than DHPG greater than BVdU greater than ACV; on the basis of the therapeutic index they were: BVdU greater than DHPG greater than FIAC greater than ACV greater than FIAU greater than FMAU. Differential inhibition of EBV-associated polypeptides by these drugs was observed.

Antiviral Agents↗
PubMed1985

Path model of reproductive disorders and performance, milk fever, mastitis, milk yield, and culling in Holstein cows.

Path analysis was used to model the direct and indirect relationships among age, previous lactation yield or estimated transmitting ability for milk, body weight, days dry, reproductive disorders, milk fever, mastitis, reproductive performance, current milk yield, and culling. Prospective data were from 784 primiparous and 2,066 multiparous Holstein lactations from 33 herds. Heifers that were older, of lighter weight, or who had lower estimated transmitting ability for milk had more problems, less milk, and poorer survival. Dystocia in heifers had several detrimental consequences including 2.9 to 4 times more retained placenta, metritis, and culling and +7.4 d more to first service. Cystic ovaries were associated directly with 376 kg greater milk yield and with a 16.5-d delay in first service. Failure to conceive at first service and mastitis increased risk of culling 5.2 to 10 times. In multiparous cows, milk fever increased risk of reproductive disorders by 1.6 to 4.2 times and indirectly contributed to poor breeding performance and increased culling. Risk of culling was increased 2.1 to 3.7 times directly by mastitis and dystocia and by poor breeding performance.

Age Factors↗
PubMed1985

Contents of hospital advertisements in the yellow pages.

Yellow pages advertisements of 252 hospitals in 13 geographically separated metropolitan areas are content analyzed. Nearly 2,000 content items are classified into 13 categories and approximately 60% of them deal with specific hospital services. Discrepancies between some of the hospitals' advertisement contents and previously identified hospital attributes favored by consumers are discovered. Recommendations regarding hospitals' use of this promotional media are made.

Advertising↗
PubMed1984

Congenital vascular anomalies causing tracheoesophageal compression.

Congenital vascular anomalies of the great vessels causing marked tracheoesophageal compression are rare. Notable symptoms usually manifest in the neonatal period and include stridor, repeated cyanotic attacks, recurrent pneumonia, and dysphagia. Although the diagnosis can often be made from barium swallow studies, the preoperative examination should nevertheless include an endoscopy. This is essential if the degree of tracheomalacia is to be adequately assessed and other tracheobronchial abnormalities are to be identified. Possible airway problems can then be anticipated, thus minimizing postoperative respiratory difficulties.

Aorta, Thoracic↗
PubMed1984

Transcription analysis of a Bacillus subtilis arg gene following cloning in Escherichia coli in an initially unstable hybrid plasmid.

Following shotgun cloning of EcoRI fragments of Bacillus subtilis DNA in pBR322, a hybrid plasmid pUL710 was isolated which complements argC but no other auxotrophs of E. coli K12. Restriction mapping, Southern blotting and other evidence suggest that pUL710 carries an insert of 1.6 kbp, and derives, by deletion of both vector and insert sequences, from a larger but unstable initial hybrid which carried a 12 kbp EcoRI fragment from the B. subtilis chromosome. RecE-dependent integration of pUL710 into the B. subtilis chromosome demonstrated homology between the insert DNA and the argO locus of B. subtilis. pUL710 was found to confer appreciable tetracycline resistance even though the deletion presumed to stabilise the hybrid had inactivated the tet promoter. The results of analysis by Tn5 mutagenesis, transcriptional fusions and run-off in vitro transcription suggest that both the cloned argC gene and the tetracycline gene in pUL710 are expressed from a B. subtilis promoter located very close to the EcoRI cloning site.

Aldehyde Oxidoreductases↗
PubMed1984

Dermatologic prescriptions requiring compounding.

Dermatologists responding to a mail survey supplied 520 prescriptions as examples of prescriptions requiring compounding. A total of 195 different ingredients were used, with an average of 2.5 ingredients per prescription. Anti-inflammatory agents were most frequently used. Brand-name medications were frequently incorporated with other ingredients.

Adult↗
PubMed1984

Sensory consequences of commissural myelotomy. A challenge to traditional anatomical concepts.

Twenty-five cases of commissural myelotomy were studied. Representative cases are reported, including a histological examination of the lesion in one. Although the purpose of the operation is to produce a cuirass of loss of pain sensibility by dividing the spinothalamic and spinoreticulothalamic fibres as they decussate in the anterior commissure of the cord, this result is not always obtained. Whether or not the expected sensory loss is obtained, the chronic pain for which the operation is performed can be relieved. Sensibility tends to return towards normal after myelotomy. Even with substantial recovery of sensory loss, the pain for which the operation was performed can remain absent. Asymmetrical sensory loss may be produced by the operation; reasons for this are suggested. Differences between the results of commissural myelotomy and anterolateral cordotomy are discussed. Unlike the results of anterolateral cordotomy, which can be accounted for on the basis of known anatomy, the results of commissural myelotomy are inexplicable on present anatomical knowledge. Attention is drawn to the results of myelotomy reported originally by Hitchcock and confirmed by other neurosurgeons in which a short myelotomy incision in the upper cervical cord caused loss of pain over a vast region of the body. The difficulty in explaining the patterns of sensory loss in these cases is discussed. The literature on pathways alternative to the spinothalamic and spinoreticulothalamic is reviewed. It is argued that the central incision cannot cause relief of pain merely by cutting an afferent pathway, and it is suggested that this lesion blocks impulses entering into, in, or leaving the spinothalamic complex. The accurate localization of pinprick and thermal stimuli via the spinothalamic tract is demonstrated.

Afferent Pathways↗
PubMed1984

Topographical anatomy of the posterior columns of the spinal cord in man. The long ascending fibres.

Nine cases are presented which illustrate the segmental anatomy of the posterior columns with respect to the long ascending fibres. It is concluded that the fasciculus gracilis (FG) and the fasciculus cuneatus (FC) should be considered as separate anatomical entities. It is shown that the shape of each fasciculus is different in, and characteristic of, each of the upper thoracic and cervical segments. A certain degree of segmental lamination is present in the FG, but with extensive overlapping of fibres from different segments. The orientation of the laminae is not the same in all segments, being very approximately parallel to the medial border of the posterior horn in most caudal segments, approximately parallel to the median septum in intermediate segments, and oblique in an anteromedial posterolateral direction in cranial sections. The pattern of lamination in the FC and the degree of overlapping of fibres resembles that in the caudal FG. There is no, or minimal, overlapping of fibres of the FC with those of the FG. The most medial fibres of the FC, lying along the lateral border of the FG, are in proximity with fibres, in that fasciculus, from many different segments.

Afferent Pathways↗
PubMed1984

Antagonistic action of retinoic acid against teleocidin and 12-O-tetradecanoyl-phorbol-13-acetate on activation of Epstein-Barr virus genomes.

Teleocidin, a new potent tumor promoter, produces biological effects similar to 12-O-tetradecanoyl-phorbol-13-acetate (TPA) on human lymphoblastoid cell lines. A wide range of concentrations (4-16 ng/ml) of teleocidin were optimal for induction of replication of latent Epstein-Barr virus (EBV) genomes in P3HR-1 cells; cell growth was significantly inhibited in this dose range. In contrast, treatment of Raji cells with an identical dose range of teleocidin did not induce replication of latent EBV genomes. As with TPA, P3HR-1 cells in the stationary phase were twice as responsive to teleocidin induction as exponentially growing cells. The activation of P3HR-1 cells both by teleocidin and TPA greatly enhanced the synthesis of EBV DNA and EBV-associated polypeptides as determined by cRNA - DNA hybridization and by analysis on polyacrylamide gels. Both drugs also increased production of biologically active virus as monitored by the synthesis of viral DNA in superinfected Raji cells. These effects were completely inhibited by retinoic acid. However, retinoic acid did not inhibit the spontaneous viral DNA replication that occurs in P3HR-1 cells not treated with the inducers. Thus, it appears that retinoic acid antagonizes the inducing effects of TPA and teleocidin, but not viral replication itself.

Alkaloids↗
PubMed1984

Energetics of tetracycline transport into Escherichia coli.

The nature of energy coupling for the active transport of tetracycline into Escherichia coli was examined under conditions in which antibiotic uptake was directly compared with transport of proline (proton motive force dependent) and glutamine (phosphate bond dependent). Tetracycline transport was partially inhibited by osmotic shock and by exposure of bacteria to arsenate, two procedures which substantially reduced glutamine transport. Tetracycline transport was also partially inhibited in an uncB mutant (AN283) exposed to the uncoupler carbonyl cyanide-m-chlorophenyl hydrazone (CCCP) under conditions that inhibited proline transport. Taken together, these data indicate involvement of both phosphate bond hydrolysis and the proton motive force for the active transport of tetracycline into E. coli.

Arsenates↗
PubMed1984

Prolonged inhibitory effect of 9-(1,3-dihydroxy-2-propoxymethyl)guanine against replication of Epstein-Barr virus.

The effects of 9-(1,3-dihydroxy-2-propoxymethyl)guanine (DHPG), a new antiviral drug, and acyclovir (ACV) [9-(2-hydroxyethoxymethyl)guanine] on the replication of Epstein-Barr virus (EBV) were compared. Both drugs inhibited EBV DNA replication in P3HR-1 cells and superinfected Raji cells, but neither inhibited replication of the plasmid form of the EBV genome in latently infected Raji cells. However, DHPG had a more prolonged inhibitory effect than ACV. Although the effect of the drugs is prompt, the kinetics of inhibition of EBV replication indicated that a drug exposure of 14 days was needed to reduce the EBV genome copy number to the residual plasmid level (30 copies per cell). The inhibitory effect of ACV was readily reversed within 11 days after removal of the drug, in contrast to the more prolonged effect exerted by DHPG, which persisted for more than 21 days. The 50% inhibitory doses for cell growth of ACV and DHPG were estimated to be 250 and 200 microM, respectively. The viral 50% and 90% effective doses of inhibition were, respectively, 0.3 and 9 microM for ACV and 0.05 and 3 microM for DHPG. The therapeutic indices (50% inhibitory dose/50% effective dose) for ACV and DHPG were 833 and 4,000, respectively. Synthesis of EBV-associated polypeptides was also affected. In superinfected Raji cells, ACV (100 microM) and DHPG (30 microM) inhibited synthesis of polypeptides with molecular weights of 145,000 and 140,000; in addition, synthesis of polypeptides with molecular weights of 110,000 and 85,000 was markedly reduced by DHPG but not by ACV. However, after drug removal, the inhibitory effect of ACV on polypeptide synthesis was abolished in contrast to the more persistent effect of DHPG.

Acyclovir↗
PubMed1984

High- versus low-dose methylprednisolone for acute rejection episodes in renal transplantation.

A double-blind, randomized trial was conducted to compare the efficacy and safety of two doses of methylprednisolone (MP) in reversing acute rejection episodes in renal allograft recipients. 18 subjects were randomized to receive either 250 mg (group 1) or 1,000 mg (group 2) MP daily for 4 days. The two groups were similar with regard to HLA matching, number of cadaveric grafts, number of second transplants, and transfusion history. 6 of 10 patients in group 1 and 4 of 8 in group 2 responded to treatment with MP, i.e., serum creatinine returned to baseline. 1-year follow-up has demonstrated a similar graft survival, 70% in group 1 and 50% in group 2. There were no significant differences in mortality, infectious complications, blood glucose, and blood pressure between the two groups. We conclude that (1) 250 mg MP is as effective as 1,000 mg in reversing acute rejection in renal allografts; (2) 1,000 mg MP does not result in a greater incidence of adverse effects, and (3) 250 mg MP does not adversely affect 1-year graft survival.

Acute Disease↗
PubMed1984

A study of pharmacists' involvement in drug use by the elderly.

Three hundred elderly persons in a single Mississippi county were interviewed to determine drug use patterns and relationships with pharmacists. Although three-fourths had used the same pharmacy for longer than five years, only one in six used that pharmacy as their usual source for over-the-counter (OTC) drugs. More than eight percent incorrectly identified the use of their prescription drugs and 140 instances of potential drug interaction were identified. Communications with pharmacists were limited, as only one-fifth had talked with the pharmacist at the time their last prescription was filled and only one in six mentioned the pharmacist as someone they would ask about prescription drugs.

Aged↗