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Biomedical subjects

J D Stewart

Publications and source records attributed to J D Stewart.

At least 91 records · Page 5Linked to original sources
PubMed1987

The variable clinical manifestations of ulnar neuropathies at the elbow.

In twenty-five cases of ulnar neuropathy at the elbow, the involvement of the fibres from three sensory and to four motor branches were examined clinically and, where possible, electrophysiologically. Of the sensory fibres, those from the terminal digital nerves were most commonly involved. The fibres to the hand muscles were much more frequently involved than those to the forearm muscles. These findings suggest that in ulnar neuropathies at the elbow there is variable damage to the fascicles within the nerve.

Action Potentials↗
PubMed1986

Occupational cadmium exposure in jig solderers.

The cadmium body burden, blood and urine cadmium concentrations, and renal function were studied in a group of 53 cadmium solderers. The results showed raised blood and urine cadmium concentrations and raised cadmium body burden in all workers (31) with more than five years exposure, with 27 having urine cadmium concentrations in excess of the proposed biological threshold of 10 nmol/mmol creatinine. Renal tubular dysfunction was found in 17 of the subjects with more than five years exposure and in one this was associated with glomerular dysfunction. These data indicate that cadmium body burden and frequency of tubular dysfunction in end users of cadmium may be as high as those found in smelters or production workers. Subjects with tubular dysfunction did not show greatly increased urine cadmium concentrations compared with those without dysfunction, supporting a previous suggestion that tubular dysfunction occurs before the wash out of cadmium from the kidney. At the time of our study, cadmium exposure stopped as cadmium free soldering rods were introduced. Repeat urine samples from 19 subjects, one to two years after exposure ended indicated that there was no further increase in the level of excretion of low molecular weight proteins, perhaps indicating that the tubular proteinuria does not increase or more severe renal dysfunction develop without continuous exposure.

Adult↗
PubMed1986

Electrodiagnostic techniques in the evaluation of nerve compressions and injuries in the upper limb.

Nerve conduction studies and the needle examination of muscles (EMG) are valuable aids in the evaluation of acute and chronic focal neuropathies. A careful clinical examination, however, remains the best way to assess patients with these disorders. In an acute and apparently complete nerve lesion, the main drawbacks of electrophysiologic testing are that a full evaluation cannot usually be done before 10 days after the injury, and the differentiation between axonotmesis and neurotmesis cannot be made.

Acute Disease↗
PubMed1985

Formation of bacterial mutagens from the reaction of chewing tobacco with nitrite.

Using the Salmonella/microsome assay system, the mutagenicity of chewing tobacco extracts (CTE) treated with and without sodium nitrite under acidic conditions was examined. Mutagenic activity was found only for nitrite-treated CTE in both tester strains, TA98 and TA100, and was independent of metabolic activation. Formation of mutagenic substances from CTE by nitrite was dependent on acidic pHs (the highest at pH 2) and could be inhibited by ascorbate. The mutagenic potency of CTE plus nitrite was proportional to the content of nitroso compounds generated in the reaction mixture, indicating that the nitrosation process was involved. The possible in vivo nitrosation and the potential health effect are discussed.

Animals↗
PubMed1985

Patterns of infection and mortality in thoracic trauma.

Tissue infection and systemic sepsis are common causes of morbidity and late mortality after major thoracic trauma. To seek causative mechanisms, prognostic indicators, and areas of possible improvement in therapy, we reviewed 310 consecutive adults admitted with major thoracic trauma. Of these, 56 (18%) died of massive injuries in the first 5 days; the remaining 254 were considered at risk for infectious complications. There were 21 late deaths in this group, and 15 (71%) were caused by systemic sepsis. Eighty-four patients (33%) developed thoracic infections, and 15 (6%) had significant nonthoracic infections. Markers of increased risk of infection included blunt injury, shock and unconsciousness on arrival, and splenectomy. Pulmonary infection was increased significantly following prolonged endotracheal intubation, but was virtually absent following tracheostomy. The risk of infection was increased significantly if prophylactic antibiotics were not used, but no definite correlation could be made to advanced age, pre-existent disease, nor post-traumatic malnutrition. Attention to some of these factors may decrease the risk of infection in thoracic trauma.

Abdominal Injuries↗
PubMed1983

Mutagenic detection of complex environmental mixtures using the Salmonella/arabinose-resistant assay system.

The mutagenic sensitivity of SV50, the R-factor plasmid containing tester, of the Salmonella/arabinose-resistant assay system has been evaluated with different environmental complex mixtures, including extracts of airborne and diesel emission particles, oil-shale ash, nitrosated coal dust and water samples. The mutagenicities of all extracts were detectable with this assay. This study indicates that the arabinose-resistant assay with SV50 is useful for the detection of the mutagenic activity of environmental complex mixtures.

Air Pollutants↗
PubMed1983

Computed tomography in the evaluation of plexopathies and proximal neuropathies.

We describe nine patients with plexopathies or proximal mononeuropathies due to mass lesions. In four, computed tomography (CT) was the only radiological technique to show the cause of the neuropathy. In five patients, CT either unequivocally confirmed the presence of an abnormality or was superior to other imaging techniques in showing its full anatomical extent. CT scanning is a valuable aid in the assessment of lesions of the peripheral nervous system, particularly plexopathies and mononeuropathies caused by retroperitoneal, pelvic or superior pulmonary sulcus tumors.

Adolescent↗
PubMed1982

Inflammatory myopathy in a captive Bengal tiger.

A 9-year-old female Bengal tiger (Panthera tigris tigris) was presented with a history of progressive hindlimb weakness and muscle atrophy. Serum muscle enzyme activities were high, and electrophysiologic examination suggested an underlying myopathic process. Muscle biopsy revealed an inflammatory myopathy, with multifocal collections of inflammatory cells. There was severe muscle fiber necrosis with some evidence of regeneration. The cellular infiltrate consisted predominantly of macrophages, with a few lymphocytes and plasma cells. Evidence of parasitism or viral infection was not detected. Despite prolonged corticosteroid therapy, there was no clinical improvement or notable decrease in serum muscle enzymes activities. The tiger was euthanatized, and necropsy revealed generalized muscle inflammation, with no other pertinent findings.

Animals↗
PubMed1980

Thresholds for detection of constant rotary acceleration during vibratory rotary acceleration.

The effects of vibratory angular acceleration (aR) on detection thresholds for constant aR in a dynamic flight simulator are reported in three experiments. Detection thresholds were determined for 10 pilots and four nonpilots using a random, double-staircase procedure while the subjects sat erect in a device which rotated about an earth-vertical axis. Constant aRs were presented for 0.5 and 1.0 s with concurrent, vibratory aR at 1 and 5 Hz, and thresholds with no vibratory aR were established. The thresholds were obtained while the subjects observed a visual reference in the enclosed cockpit in two experiments and in total darkness in a third. The results confirmed earlier experiments showing an inverse relationship between the duration of constant aR and detection threshold and showed that the detection thresholds in darkness were higher than with a visual reference present. Two analyses of variance revealed no significant differences in thresholds across the three vibration conditions. These results indicate that vibratory aRs of fairly high levels can be present in a dynamic flight stimulator without masking the pilot's ability to detect either maneuver or disturbance motions.

Acceleration↗
PubMed1979

Aflatoxin inhibition of viral interferon induction.

The inhibitory effect of four basic aflatoxins on interferon induction by influenza virus in LLC-MK2 cell monolayers follows a structure-activity series with decreasing potency in the order aflatoxin B1 greater than G1 greater than B2 approximately G2. Of the four aflatoxins, B1 was the most deleterious to both cell growth and the viability of cells in confluent cultures. The fact that higher levels of influenza virus growth were attained in aflatoxin-treated cells than in normal cell monolayers was related to increased aflatoxin concentration in association with decreased interferon production. The ability of interferon to confer cellular resistance against viral infection, however, was not altered by aflatoxin. The inhibitory activity of aflatoxin on interferon production may be a factor contributing to impairment of host resistance to viral infections.

Aflatoxins↗
PubMed1979

Periodic alternating gaze.

A 77-year-old man with autopsy-proven bilateral cerebral infarction had a periodic alternating conjugate horizontal ocular deviation for 2 days, which ceased shortly before death. There have been four previously reported patients with this disorder. The phenomenon suggests acute bilateral cerebral disease with a relatively intact brainstem.

Aged↗
PubMed1978

Reaction time to accelerating lines and dots on a cathode-ray tube.

Two experiments recorded the simple RT of 13 and 10 airline pilots, respectively, to accelerating lines and dots on a cathode-ray tube. In Exp. 1, dotted lines of six lengths moved in-line or frontally, and downward or to the right. Exp. 2 compared seven different in-line-moving solid lines with dot pairs of corresponding separations, and with single dots. RT increased with the length of in-line-moving solid lines but not when dotted lines were used. RT decreased with frontal movement of dotted lines. RT to dot pairs was shorter than to solid lines or single dots. Results indicate the importance of three factors: amount of movement information, visual angle, and inhibition of the retinal area stimulated.

Humans↗