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R Smith

Publications and source records attributed to R Smith.

At least 1,279 records · Page 71Linked to original sources
PubMed1984

A comparison of methods for assessing the sedative effects of diphenhydramine on skills related to car driving.

A double blind cross-over study was performed to compare the sensitivity of "oof road" driving with that of laboratory tests of driving-related skills to drug induced sedation. Twelve experienced drivers (6 M, 6 F) received single oral doses of the H1-antagonist diphenhydramine 25, 50 and 100 mg and placebo. Each treatment was administered on 2 separate occasions, once in the driving school when real driving skills were assessed and again in the laboratory when performance of an adaptive tracking task, body sway and visual reaction were measured. On all occasions subjects assessed their own performance and alertness/sedation using visual analogue scales. Data were subjected to analysis of variance and differences assessed by Newman Keul's test. Diphenhydramine failed to impair driving performance at any dose while all doses produced significant changes in each of the 3 laboratory tests. Subjects rated themselves sedated after all 3 doses of active drug in the laboratory but only after the 100 mg dose in the driving school. Tests performed in the psychopharmacology laboratory appear to be more sensitive to the sedative effects of diphenhydramine than tests of "off road" driving. The implications are discussed.

Adult↗
PubMed1984

Large-scale isolation of the Neurospora plasma membrane H+-ATPase.

A method for the purification of relatively large quantities of the Neurospora crassa plasma membrane proton translocating ATPase is described. Cells of the cell wall-less sl strain of Neurospora grown under O2 to increase cell yields are treated with concanavalin A to stabilize the plasma membrane and homogenized in deoxycholate, and the resulting lysate is centrifuged at 13,500g. The pellet obtained consists almost solely of concanavalin A-stabilized plasma membrane sheets greatly enriched in the H+-ATPase. After removal of the bulk of the concanavalin A by treatment of the sheets with alpha-methylmannoside, the membranes are treated with lysolecithin, which preferentially extracts the H+-ATPase. Purification of the lysolecithin-solubilized ATPase by glycerol density gradient sedimentation yields approximately 50 mg of enzyme that is 91% free of other proteins as judged by quantitative densitometry of Coomassie blue-stained gels. The specific activity of the enzyme at this stage is about 33 mumol of P1 released/min/mg of protein at 30 degrees C. A second glycerol density gradient sedimentation step yields ATPase that is about 97% pure with a specific activity of about 35. For chemical studies or other investigations that do not require catalytically active ATPase, virtually pure enzyme can be prepared by exclusion chromatography of the sodium dodecyl sulfate-disaggregated, gradient-purified ATPase on Sephacryl S-300.

Cell Membrane↗
PubMed1984

Health beliefs and rehabilitation after lumbar disc surgery.

Thirty per cent of patients fail to rehabilitate after back surgery. Pre-operative physical assessment cannot reliably identify these patients. A questionnaire assesses the health beliefs and extent of rehabilitation in 200 patients who have undergone a laminectomy. Objective medical data and ten subjective scales are analyzed, which correlate very highly with quality of rehabilitation. The questionnaire identifies 'at risk' individuals far better than objective physical findings, and it makes specific pathological attitudes clear. These attitudes can be used to direct existing post-operative care resources in an efficient way.

Adult↗
PubMed1984

Tumorigenesis by mouse mammary tumor virus: proviral activation of a cellular gene in the common integration region int-2.

Approximately 50% of tumors induced by mouse mammary tumor virus (MMTV) contain an acquired provirus within a limited region of chromosomal DNA, termed int-2. We have extended our previous characterization of this locus and have mapped provirus integration sites in 21 independent tumors. Although integration occurs at multiple sites, proviruses within int-2 are distributed into two oppositely oriented groups whose transcription is directed away from a central domain. Provirus insertion in int-2 is accompanied by expression of RNA derived, at least in part, from this central domain. Since the RNA is not detected in normal mammary tissue, we conclude that MMTV integration activates the expression of a cellular gene within int-2 and that this event may contribute to tumorigenesis.

Animals↗
PubMed1984

Pharmacokinetics of clindamycin phosphate in the first year of life.

The pharmacokinetics of intravenously administered clindamycin phosphate was studied in 40 children less than 1 year of age. Mean peak serum concentrations were 10.92 micrograms/ml in premature infants less than 4 weeks of age, 10.45 micrograms/ml in term infants greater than 4 weeks, and 12.69 micrograms/ml in term infants less than 4 weeks of age. Mean trough concentrations were 5.52, 2.8, and 3.03 micrograms/ml, respectively, in the same groups. Serum half-life was significantly longer (8.68 vs 3.60 hours) in premature compared with term infants less than 4 weeks of age. Both premature and term infants less than 4 weeks had significantly decreased clearance when compared with infants greater than 4 weeks (0.294 and 0.678, respectively, vs 1.58 L/hr). Clearance was significantly greater (1.919 vs 0.310 L/hr) and serum half-life less (1.75 vs 7.57 hours) in infants with body weight greater than 3.5 kg. On the basis of these data it is recommended that in infants greater than 4 weeks or greater than 3.5 kg, intravenous clindamycin dosage be 20 mg/kg/day in four divided doses. In premature neonates less than 4 weeks, the dose should be reduced to 15 mg/kg/day in three divided doses. Term infants greater than 1 week of age may also receive 20 mg/kg/day in four doses.

Clindamycin↗
PubMed1984

Hypophosphataemic osteomalacia and myopathy: studies with nuclear magnetic resonance spectroscopy.

A patient with familial adult-onset hypophosphataemia, whose myopathy was closely related to the plasma phosphate concentration, was investigated by phosphorus nuclear magnetic resonance spectroscopy (31P n.m.r.) in vivo of the right flexor digitorum superficialis muscle. During hypophosphataemia induced by stopping oral phosphate a significant reduction in measured muscle strength occurred, but the ratios of the intramyocellular levels of phosphocreatine (PCr), adenosine triphosphate (ATP) and inorganic phosphate (Pi) remained unchanged at rest. During exercise these levels changed, as did the intramyocellular pH, but they did not differ from the pattern previously recorded in normal subjects. In four adults with inherited infantile-onset hypophosphataemia (vitamin D-resistant rickets, VDRR) without myopathy, the n.m.r. measurements were normal at rest and during exercise. In one patient with inherited hyperphosphataemia (tumoral calcinosis) the resting PCr: Pi ratio was significantly reduced.

Adenosine Triphosphate↗
PubMed1984

Effects of respirators under heat/work conditions.

Physiological responses and perceived strain of five unacclimatized male subjects were studied. The subjects were exposed to heat during an exercise task and were evaluated while wearing half and full facepiece, cartridge-type, air-purifying respirators, and without a respirator. The exercise consisted of walking on a treadmill for a period of 1 hour in a controlled environmental chamber at each of two different energy expenditure levels (200 and 400 Kcal/hr) (approximately equal to 58 and 116 Watts) and two different heat exposures (air temperatures of 25 degrees C and 43.3 degrees C). The results indicated that wearing a full facepiece respirator imposed significant physiological strain added to that caused by the heat and workloads used in the study. Five of the six physiological measures show this increased physiological strain: heart rate; minute ventilation; oxygen consumption; energy expenditure; and oral temperature. There was no detectable effect on sweat rate. Although subjective ratings indicated more discomfort with increasing physiological strain, the observed correlations between such measures were low (Tb less than .60). The net consequence of the significant effects indicates that workers' tolerance to moderate or higher levels of work under hot conditions while wearing a respirator is reduced. The reduction is more pronounced when wearing a full mask than when wearing a half mask. Changes in respirator design which minimize respiratory dead space are suggested to alleviate this problem. Otherwise, prevention of excessive physiological strain from respirator use when working at moderate or higher levels at hot job sites could necessitate more rest breaks or limiting work time under such conditions.

Adult↗
PubMed1984

Structure of the proteolipid protein extracted from bovine central nervous system myelin with nondenaturing detergents.

As a basis for attempts to define the structures of the proteins within myelin, methods have been developed for their extraction and isolation in solutions of non-denaturing detergents. With use of solutions of deoxycholate or Triton X-100, up to 90% of the protein has been extracted from bovine CNS myelin, along with most of the phospholipid. The proteolipid protein has been purified in deoxycholate solutions by chromatography on a blue dye-ligand column, which retained all of the basic protein and 2',3'-cyclic nucleotide-3'-phosphodiesterase, and then on Sephacryl S300, which separated proteolipid protein from phospholipid and high-molecular-weight proteins. The proteolipid protein was isolated from Triton X-100 extracts of myelin by adsorption onto phosphocellulose resin, with subsequent elution by 0.5 M sodium chloride. Gel permeation chromatography was used as the final purification step. Sedimentation equilibrium experiments gave a monomer molecular weight of 134,000 +/- 8000 in deoxycholate and 145,000 +/- 17,000 in Triton X-100 solutions. On the basis of an apparent subunit molecular weight of 23,500 it was deduced that the native protein is probably hexameric. Above 0.2 gL-1 in Triton X-100 solutions and 0.5 gL-1 in deoxycholate solutions the protein aggregated. In deoxycholate solutions the protein adopts the highly helical conformation expected for an intrinsic membrane protein.

Animals↗
PubMed1984

Comparison of the major proteins of shark myelin with the proteins of higher vertebrates.

On gel electrophoresis in dodecyl sulphate solutions shark CNS myelin showed four bands close in mobility to the proteolipid protein of bovine CNS myelin. They had apparent molecular weights of 21,000, 26,000, 27,000, and 31,500. Unlike bovine proteolipid protein, all of these shark proteins were shown to be glycosylated by staining gels with the periodate-Schiff reagent. Amino acid analyses of the polypeptides eluted from polyacrylamide gels indicated a high content of apolar amino acids and a composition approximating that of the Po protein of bovine peripheral nervous system (PNS) myelin, rather than that of the CNS proteolipid protein. The shark polypeptide of apparent molecular weight 31,500 was obtained by elution from dodecyl sulphate gels and antibodies raised against it in rabbits. By probing of electroblots with this antiserum the four shark CNS bands were shown to share common determinants with each other, with a major shark PNS protein and with sheep and chicken major PNS glycoproteins (Po). The binding of antibody was unaffected by deglycosylation of the shark CNS polypeptides with anhydrous hydrogen fluoride. Together, these results appeared to establish that shark CNS myelin contains four proteins that are closely related to a major shark PNS protein and to the Po protein of higher species.

Amino Acids↗
PubMed1984

Characterization of monoclonal antibodies to Streptococcus mutans antigenic determinants I/II, I, II, and III and their serotype specificities.

Monoclonal antibodies (McAb) were developed to four protein components of Streptococcus mutans serotype c, some of which are significant in the protection against dental caries. The six McAb used in this investigation support the identities of streptococcal antigens (SA) I/II, I, II, and III. The specificities of these antigenic determinants were established both by direct binding and inhibition with the pure SA with a solid-phase radioassay. Whereas conventional antisera to S. mutans serotype c cross-react with serotypes c, e, and f (and g), McAb to serotype c-derived SA I/II react predominantly with serotype c and show some low-titer reactivity with serotype f. The slight cross-reactivity between S. mutants cells of serotypes c and f could be further differentiated by absorption of any of the three McAb to SA I/II with cells of serotype c. Parallel studies of McAb with cells of S. mutans and their ammonium sulfate-precipitated culture supernatants suggest that some SA determinants are retained predominantly on the cell surface, but others are readily shed into the culture medium, so that they are detected both on the cell surface and culture medium. Unlike polyclonal antibodies, McAb are capable of discriminating single antigenic determinants and can be applied to the study of shedding of antigens from microorganisms into the environment, such as the gut or gingival sulcus.

Animals↗