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Biomedical subjects

D R Clark

Publications and source records attributed to D R Clark.

At least 37 records · Page 2Linked to original sources
PubMed1990

A prospective study of the incidence and nature of injuries to adult rugby players.

The incidence and nature of injuries occurring in 8 adult club rugby teams was followed prospectively during the 1988 rugby season. The findings were compared with those from two similar studies in schoolboy rugby players. A total of 114 injuries were sustained by 78 players; 85% of injuries occurred during matches. Injury was most prevalent during the first 8 weeks of the season and again after the mid-season break. Hookers (19%), wings (15%), fullbacks (11%) and centres (10%) were the players most often injured. Injury occurred most commonly when the player was tackled (26%), during open play (21%) and during the loose scrum (17%). Muscles (33%) and ligaments (32%) were the anatomical structures most often injured. Injury caused 35% of injured players to miss more than 35 days of rugby. Thirteen per cent of injured players did not play again for the rest of the season and only 14% of injured players returned to rugby after 7 days or less. Prolonged disability was associated with ligament injuries (57%), dislocations (17%) and fractures (10%).

Adult↗
PubMed1989

Selenium accumulation by raccoons exposed to irrigation drainwater at Kesterson National Wildlife Refuge, California, 1986.

In February-March 1986, eight raccoons (Procyon lotor) were collected at Kesterson Reservoir (Merced Co., California), which had received selenium-contaminated irrigation drainwater, and four raccoons were collected at the nearby Volta Wildlife Area, which had not. Selenium concentrations in Kesterson raccoons averaged 19.9 ppm (micrograms/g dry wt) in liver, 28.3 ppm (dry wt) in hair, 21.6 ppm (dry wt) in feces, and 2.61 ppm (wet wt) in blood and exceeded Volta concentrations by 12, 30, 21, and 10 times, respectively. Selenium concentrations in livers of Kesterson raccoons were less than those in five of nine other mammal species sampled in 1984. Selenium concentrations in hair provided the strongest statistical separation between study areas. Hemoglobin levels in two Kesterson raccoons equalled levels reported in rats with selenium-induced anemia, but the raccoons showed no illness. Amyloidosis in one Kesterson raccoon may have been selenium-induced. Our data indicate that raccoon births peaked about 2 months later than was previously reported. Based on our sample of 12 raccoons, we found no evidence that contamination by irrigation drainwater had negative effects on raccoons inhabiting Kesterson.

Animals↗
PubMed1989

Recognition of Fusobacterium nucleatum subgroups Fn-1, Fn-2 and Fn-3 by ribosomal RNA gene restriction patterns.

DNA from representative strains of Fusobacterium nucleatum subgroups Fn-1, Fn-2 and Fn-3 was digested with restriction enzymes EcoRI and TaqI and the electrophoretically separated fragments hybridized with a 32P-16S rRNA gene probe from E. coli. The rRNA gene restriction patterns from DNA digested with either enzyme allowed the clustering of strains into the three subgroups. However, TaqI digested DNA yielded a wider distribution of taxonomically useful bands (ca 0.65 +/- 14.3 kbp) and the pattern produced was characteristic of each subgroup. The present method is a simple and reliable means of identifying the three subgroups of F. nucleatum and provides a useful method for further studies of the heterogeneity of F. nucleatum.

Blotting, Southern↗
PubMed1989

Effect of weight loading on the coronary band interstitial fluid pressure in horses.

Interstitial fluid pressures, as a possible function of limb load, were measured at 2 sites within the digital coronary dermis of both cranial digits in 10 standing horses. Fluid pressure changes and digital load measurements were simultaneously detected and recorded by use of, respectively, modified wick-in-needle and force plate transducers coupled to a microcomputer. Mean pressures, recorded at limb loads between 50 and 80 kg, were 2.29 +/- 3.17 mm of Hg at the toe and 2.49 +/- 5.91 mm of Hg at the heel. Mean pressures, recorded between 150 and 180 kg, were 5.01 +/- 5.23 mm of Hg at the toe and 1.28 +/- 7.69 mm of Hg at the heel. These data indicate that, in the static limb, no statistically significant change in interstitial fluid pressure occurs at loads up to 180 kg.

Animals↗
PubMed1988

Extensive tumor resection under deep hypothermia and circulatory arrest.

The risk of fatal hemorrhage may limit the completeness of resection in hepatic malignancies and in vascular extensions of Wilms' tumors. We have used Ein's technique of deep hypothermia (average 17 degrees C) with cardiac arrest (average 39 minutes) and exsanguination in performing five hepatic and two intravenous Wilms' tumor resections. The initial hepatic resection takes less than 15 minutes to perform in a bloodless field and the specimen is immediately examined by frozen section for determination of adequacy of margin. Additional resection is easily performed. Of four trisegmentectomies and one left lobectomy, two required additional resections. Mattress sutures were used to control hemorrhage during recirculation. One patient died from bleeding and cardiac decompensation and another from recurrence of tumor. The Wilms' tumors extended from the iliac vein into the right atrium in one child and from the right renal vein to the right atrium with extensions into the hepatic and lumbar veins in another. After nephrectomy, the atria and inferior vena cava were opened and the tumor extracted under direct vision. Both patients are well.

Carcinoma, Hepatocellular↗
PubMed1988

Pritt Tak: another hazard of grommets and swimming.

There is argument about whether, whilst swimming, water should be excluded from ears which have middle ear ventilation tubes in place in the tympanic membrane. The adhesive putty substance BLU-TACK (registered Trade Mark, Bostik Ltd, Leicester, England, LE4 6BW) has been suggested as an effective ear plug for this purpose. A case is described in which an alternative adhesive putty substance was used as a waterproof plug. The result was that the plug became semi-solid and impossible to remove without the use of micro instruments and removal would have required general anaesthetic in a less co-operative patient. Patients should be warned of this risk.

Adhesives↗
PubMed1988

Epstein-Barr virus and epithelial cells: implications for the otolaryngologist.

Epstein-Barr Virus (EBV) is an oncogenic herpesvirus associated with two human malignancies. Initially linked in the etiology of Burkitt's lymphoma, a B cell lymphoma, it has subsequently been implicated in the causation of nasopharyngeal carcinoma, an epithelial tumor of considerable world health importance. More recently a number of head and neck tumors have been shown to harbor the virus, suggesting a possible role for EBV in their development.

Burkitt Lymphoma↗
PubMed1987

Selenium accumulation in mammals exposed to contaminated California irrigation drainwater.

In May 1984, 332 mammals of 10 species were collected at Kesterson Reservoir (San Joaquin Valley, Merced Co., CA), which had received selenium-laden irrigation drainwater, and at the nearby Volta Wildlife Area, which had not. The study concentrated on the California vole (Microtus californicus); 88 were taken at Kesterson, 89 at Volta. Mean selenium concentrations in livers were as much as 522 times higher at Kesterson. There were species-to-species differences at Kesterson; higher selenium concentrations occurred in carnivorous species and/or species that feed on foods closely linked to pond water. There were also pond-to-pond differences at Kesterson; drainwater historically was delivered to Ponds 1 and 2, where concentrations in 1984 were higher, with subsequent flow to other ponds, where they were lower. Whereas none of 50 adult female voles from Kesterson was pregnant, 12 of 41 (29%) from Volta were pregnant. However, this cessation of reproductive activity at Kesterson was probably not due to selenium toxicity but could have resulted because drying conditions at Kesterson forced voles to a seed diet earlier than at Volta. One malformation was found among five embryonic litters of three species from Kesterson. Mammals seem much less susceptible to selenium-induced embryonic abnormalities than birds. No adverse impacts of selenium on wild mammals were demonstrated; however, some sensitive species might have been extirpated from Kesterson before this study began. In addition, high concentrations in small mammal species at Kesterson may threaten predatory birds and mammals that feed on them, with the endangered San Joaquin kit fox (Vulpes macrotis mutica) of particular concern.

Abnormalities, Drug-Induced↗
PubMed1987

The presentation of laryngeal tuberculosis.

Laryngeal tuberculosis is now a rare disease. We report 6 patients presenting within a 10-year period (1976-1986). Symptoms and signs often mimic carcinoma or chronic non-specific laryngitis. Greater clinical awareness and a chest radiograph prior to direct laryngoscopy may alert the clinician to the possibility of tuberculosis. The diagnosis is established by laryngeal biopsy.

Adolescent↗
PubMed1987

Detection and confirmation of cocaine use by chromatographic analysis for methylecgonine in urine.

Methylecgonine is a common metabolite of cocaine in man. We prepared methylecgonine and developed thin-layer chromatographic and gas-chromatographic methods for its detection in urine. Seventy urine specimens from our drug screening laboratory were tested by our method and by EMIT. Both methods were positive for 26 urines, and both were negative for 42 urines. The other two urines were shown to contain cocaine by GC/MS, and no detectable metabolites. We thus demonstrated that detection of methylecgonine and cocaine is as sensitive a test for cocaine use as EMIT.

Chromatography, Gas↗
PubMed1986

Abbott TDx, Dade Stratus, and Du Pont aca automated digoxin immunoassays compared with a reference radioimmunoassay method.

Automated digoxin immunoassays with the Abbott TDx, Dade Stratus, and Du Pont aca were evaluated against an RIA similar to the Centers for Disease Control Candidate Reference Method. All three automated methods correlated poorly with the reference method. Particularly disconcerting were the falsely increased values (up to 0.6 micrograms/L) obtained by the Stratus for blank specimens. We discuss the inaccuracies of the results in terms of sample matrix effects, calibrator problems, lot-to-lot reagent variation, and our laboratory requirements. We strongly support the acceptance of the CDC Candidate Reference Method for digoxin and the establishment of a standardized protocol for determining the accuracy of digoxin measurements.

Autoanalysis↗