Search PubMed⌕ Search

Biomedical subjects

G R Smith

Publications and source records attributed to G R Smith.

At least 181 records · Page 10Linked to original sources
PubMed1991

Two-point fixation of the lumbar spine. Differential stability in rotation.

Single vertebral motion segments were tested in torsion. The adjacent vertebrae were transfixed by two 3-mm Steinman pins placed vertically. These were applied in five different positions: between the anterior vertebral bodies, posterior vertebral bodies, pedicles, transverse processes, and lamina. Rotational displacement was limited the most by transfixation between the vertebral bodies (position one or two). Disrupting the anulus fibrosus significantly increased rotation in all positions except those in the vertebral body. These findings may imply that spinal fixation devices that engage the vertebral bodies may offer inherent advantages over purely posterior devices in stabilizing a vertebral motion segment. In addition, an interbody arthrodesis may prevent intervertebral motion better than a posterior or posterolateral fusion.

Adult↗
PubMed1991

Diagnostic concordance in primary care somatization disorder.

A sample of 196 primary care patients with multiple unexplained complaints was used to examine diagnostic concordance between the Feighner criteria, the Research Diagnostic Criteria, DSM-III criteria, and DSM-III-R criteria for somatization disorder. The DSM-III-R diagnostic criteria for somatization disorder maintain a high concordance with the DSM-III criteria for somatization disorder (Kappa = 0.91), a moderate concordance with the Feighner criteria (Kappa = 0.66), but only a fair concordance with the Research Diagnostic Criteria (Kappa = 0.47). These results provide further evidence that DSM-III-R describes a slightly different sample of somatization disorder patients than does the Feighner and Research Diagnostic Criteria.

Adult↗
PubMed1990

Suspected botulism in cattle associated with poultry litter.

Botulism was diagnosed clinically in grazing cattle on three closely sited dairy farms. The evidence suggests that the source of the toxin was poultry carcases containing types C and D Clostridium botulinum. These organism were also found in the alimentary tract of affected animals. Silage is suspected as having acted as a vehicle for the organisms and, or, toxins in cases which occurred later in housed cattle on one of the farms.

Animal Husbandry↗
PubMed1990

Action of RecBCD enzyme on cruciform DNA.

We tested the hypothesis that RecBCD enzyme of Escherichia coli resolves pre-existing Holliday recombination intermediates by examining the action of the purified enzyme on an open-ended DNA cruciform with limited ability to branch migrate. The enzyme cleaved two strands of the cruciform near its base to produce "recombinant" products, with a marked bias in the direction of cleavage. The two nicks necessary to cleave the cruciform were made separately. Cruciforms whose four termini were blocked by synthetic hairpin-shaped oligonucleotides were not detectably nicked by the enzyme. With one terminus open the enzyme made a nick at the base of the cruciform but not a double-strand cut. With two or more termini open the enzyme made double-strand cuts. We infer that RecBCD enzyme molecules must enter the termini of duplex DNA and approach the cruciform from more than one direction in order to cleave it into recombinant products. Previous results on RecBCD-mediated recombination between phage lambda and lambda dv imply that intracellular RecBCD enzyme can approach pre-existing Holliday junctions from only one direction. We infer that intracellular RecBCD enzyme cannot cleave pre-existing Holliday junctions into recombinants and suggest that the enzyme may cleave Holliday junctions in whose formation it participates.

Base Sequence↗
PubMed1990

Emotional processing and fear measurement synchrony as indicators of treatment outcome in fear of flying.

Minimal-therapist-involvement stress inoculation training was used to treat flying phobics. Relative to no-treatment controls, treatment subjects reported more fear reduction, were more likely to participate in an exposure session, and flew more during a two-month follow-up period. Subjects who exhibited synchronous changes in heart rate and report of anxiety during exposure had greater fear reduction than subjects showing less synchrony. Subjects who voluntarily took plane flights in the two months following treatment showed greater indications of emotional processing during in vivo exposure. Relative to flight avoiders, fliers had higher mean heart rate in the plane, a greater reduction in heart rate from the beginning to the end of the flight, and greater reported fear reduction from pre- to post-flight.

Adult↗
PubMed1990

O-phosphohydroxylysinuria: a new inborn error of metabolism?

An abnormal ninhydrin positive compound was observed in the urine of two unrelated patients with neurological abnormalities. The compound was isolated by cation exchange followed by preparative paper chromatography and finally purified via cation exchange column chromatography. Its identification as O-phosphohydroxylysine resulted from FAB mass spectrometry and NMR spectroscopy. Chemical synthesis confirmed the structure. It was tentatively postulated that these patients had a defect of the metabolism of hydroxylysine, viz., a deficiency of the enzyme O-phosphohydroxylysine phospholyase.

Adolescent↗
PubMed1990

Screening indexes in DSM-III-R somatization disorder.

A sample of 196 general medical patients with multiple unexplained somatic complaints was used to compare the performance (sensitivity and specificity) and positive and negative predictive values for the published screening indexes for somatization disorder. This study shows similar performances for both the DSM-III-R and the Swartz et al. screening indexes for somatization disorder with use of DSM-III-R diagnostic criteria. By use of Receiver Operating Characteristic (ROC) curve analysis, graphs of achievable sensitivity and specificity through the range of possible symptom thresholds allow for a more informed decision to be made concerning which screening index to use at a given symptom threshold. Positive predictive values for screening indexes ranged from 68% to 79%, and negative predictive values ranged from 72% to 81%. Use of a screening index is suggested in medical patients with unexplained complaints and in patients seen in the consultation-liaison (CL) setting.

Humans↗
PubMed1990

Experimental observations on the pathogenesis of necrobacillosis.

Earlier studies showed that the minimum infective dose (greater than 10(6) organisms) of a virulent strain of Fusobacterium necrophorum could be greatly reduced by suspending the fusobacteria in sub-lethal doses of cultures of other bacteria such as Escherichia coli before inoculating mice subcutaneously. In the present study the infective dose of the same strain of F. necrophorum was reduced by a factor of greater than 10(3) by suspending the fusobacteria in sub-lethal doses of 5% homogenate of gaur or wallaby faeces. Sterile faecal filtrate had no such effect. The sites of low grade infection produced by the prior subcutaneous injection of E. coli culture or gaur faecal suspension were susceptible to superinfection by doses of F. necrophorum far below those required to infect normal tissue. This work helps to explain the production of necrobacillosis by the faecal contamination of small wounds. It proved impossible, however, to produce necrobacillosis in mice by the subcutaneous injection of faecal suspensions from 33 farm cattle. This suggests that the proportion of cattle with virulent F. necrophorum in their faeces is low.

Animals↗
PubMed1990

Genetic dissection of the biochemical activities of RecBCD enzyme.

RecBCD enzyme of Escherichia coli is required for the major pathway of homologous recombination following conjugation. The enzyme has an ATP-dependent DNA unwinding activity, ATP-dependent single-stranded (ss) and double-stranded (ds) DNA exonuclease activities, and an activity that makes a ss DNA endonucleolytic cut near Chi sites. We have isolated and characterized ten mutations that reduced recombination proficiency and inactivated some, but not all, activities of RecBCD enzyme. One class of mutants had weak ds DNA exonuclease activity and lacked Chi-dependent DNA cleavage activity, a second class lacked only Chi-dependent DNA cleavage activity, and a third class retained all activities tested. The properties of these mutants indicate that the DNA unwinding and ss DNA exonuclease activities of the RecBCD enzyme are not sufficient for recombination. Furthermore, they suggest that the Chi-dependent DNA cleavage activity or another, as yet unidentified activity or both are required for recombination. The roles of the RecBCD enzymatic activities in recombination and exclusion of foreign DNA are discussed in light of the properties of these and other recBCD mutations.

Adenosine Triphosphate↗
PubMed1989

Activation of Chi recombinational hotspots by RecBCD-like enzymes from enteric bacteria.

Chi sites, 5'G-C-T-G-G-T-G-G-3', enhance homologous recombination in Escherichia coli and are activated by the RecBCD enzyme. To test the ability of Chi to be activated by analogous enzymes from other bacteria, we cloned recBCD-like genes from diverse bacteria into an E. coli recBCD deletion mutant. Clones from seven species of enteric bacteria conferred to this deletion mutant recombination proficiency, Chi hotspot activity in lambda Red- Gam- vegetative crosses, and RecBCD enzyme activities, including Chi-dependent DNA strand cleavage. Three clones from Pseudomonas aeruginosa and Ps. putida conferred recombination proficiency and ATP-dependent nuclease activity, but neither Chi hotspot activity nor Chi-dependent DNA cleavage. These results imply that Chi has been conserved as a recombination-promoting signal for RecBCD-like enzymes in enteric bacteria but not in more distantly related bacteria such as Pseudomonas spp. We discuss the possibility that other, presently unknown, nucleotide sequences serve the same function as Chi in Pseudomonas spp.

Adenosine Triphosphate↗