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Biomedical subjects

R B Thomson

Publications and source records attributed to R B Thomson.

48 records · Page 3Linked to original sources

Contamination of cultures processed with the isolator lysis-centrifugation blood culture tube.

Overall contamination (on- plus off-streak) of the Isolator (Du Pont Co.) blood culture tube (23%) was greater than that of a conventional broth blood culture bottle (0.6%) or that of a biphasic blood culture bottle (1.3%). To determine the source of this contamination, Isolator cultures of blood from 59 healthy volunteers and of sterile broth from 60 vials were made. A total of 37% of the blood cultures and 22% of the broth cultures were contaminated (P = 0.06). Staphylococcus epidermidis-contaminated cultures represented 31 and 10% of the blood and broth cultures, respectively (P = 0.06). Contamination of plates processed on a bench top, in front of horizontal laminar flow, and in a biological safety cabinet with vertical laminar flow were compared. Processing plates in a biological safety cabinet resulted in a significant reduction in the number of contaminated plates (P less than 0.05). The contamination rate for 7,874 Isolator blood cultures processed in the biological safety cabinet was significantly decreased to 6.7% on-streak (9.3% on- plus off-streak). Contamination of Isolator-processed blood cultures originated from the laboratory and the patient. The former can be reduced by inoculating plates in a vertical laminar flow biological safety cabinet and by maintaining adequate quality control of media. The latter may be unavoidable.

Bacteriological Techniques↗

Evaluation of nine different types of enuresis alarms.

One hundred enuretic children were treated in closely supervised trial conditions with nine commonly used enuresis alarm systems available commercially in the United Kingdom. Although there was little difference between the systems in terms of their effectiveness in stopping bed wetting, parents preferred the Eastleigh and Urilarm De-Luxe models which had distinct advantages in respect of false alarms, breakdowns, and durability of pads. Enuresis alarms that perform poorly in these respects may lead to loss of enthusiasm and non-compliance. The systems vary widely in price, but a private buyer may find a cheaper alarm just as effective.

Adolescent↗

Cimetidine in primary duodenal ulcer in children.

Of 16 children with primary duodenal ulcer, 11 had complete relief of symptoms with initial full dose cimetidine therapy. After stopping cimetidine two of these 11 relapsed, six are in remission and three occasionally complain of abdominal pain requiring antacids. The remaining five children showed no improvement at all. Only one out of the 16 children showed side-effects due to cimetidine. Although there was wide variation in dosage of cimetidine and duration of therapy, no significant difference was noted in the dosage regimen of responders and non-responders to cimetidine. We suggest, full dose cimetidine 20 to 40 mg/Kg/day for 4 to 8 weeks, followed by 8 mg/Kg nocte daily for another 4 to 8 weeks.

Child↗

Acridine orange staining of Pneumocystis carinii.

Acridine orange was used to stain smears of mouse lung which contained cyst and trophozoite forms of Pneumocystis carinii. Trophozoite forms stained yellow to orange; however, cyst forms did not stain. Acridine orange is a rapid and sensitive method for demonstrating trophozoites of P. carinii in mouse lung tissue.

Acridine Orange↗

Comparison of two methods used to prepare smears of mouse lung tissue for detection of Pneumocystis carinii.

The laboratory diagnosis of Pneumocystis carinii pneumonia in humans includes the identification of cysts in stained lung tissue impression smears. By using a mouse model, we compared the number of cysts in lung tissue impression smears with those contained in a concentrate of homogenized lung tissue. Eleven C3H/HEN mice developed P. carinii infection after corticosteroid injections, a low protein (8%) diet, and tetracycline administered in drinking water. Impression smears were prepared with freshly bisected lung tissue. Smears of concentrates were prepared with sediment from centrifuged lung tissue homogenates. All smears were made in duplicate, stained with toluidine blue O or methenamine silver, coded, randomized, and examined. The concentrate preparations contained more cysts per microscopic field than the impression preparations (P less than 0.01). Concentrates prepared by grinding with a mortar and pestle contained more cysts than concentrates prepared by blending with a Stomacher (P less than 0.05). Cysts were detected equally well with either the toluidine blue O or silver stain (not significant). Lung tissue concentrates were superior to lung tissue impressions for detecting P. carinii cysts in mice. Use of lung tissue concentrates should be considered for the diagnosis of human P. carinii infection.

Animals↗

Growth of immigrant children in the centre of Glasgow.

One hundred and ninety six Asian, 89 African, 96 Chinese and 98 Scottish children from 173 families were studied to assess growth in relation to country of birth, time of parental residence in Scotland, child order in family, social class, living conditions and dietary factors. The growth measurements (standardised height, weight and bone age) differed between ethnic groups. The Africans were the tallest and Scottish the shortest. In all immigrant groups, children born in Scotland were on average, taller and more advanced in bone age than those born in their country of origin. In this study, there was no demonstrable effect on growth of social class or of living conditions. Dietary variable showed a lack of coherent effects on growth.

Adolescent↗

Aminoglycoside antibiotics and renal function: changes in urinary gamma-glutamyltransferase excretion.

The urinary excretion of the renal proximal tubular enzyme, gamma-glutamyltransferase (gamma-GT), has been studied in 41 patients receiving tobramycin, gentamicin or streptomycin for a variety of infections. All patients receiving tobramycin or gentamicin have shown increased excretion of gamma-GT in the urine. Only 46% of those receiving streptomycin have shown an increase in gamma-GT excretion and this is of a lesser degree. A change in creatinine clearance which could only be explained by antibiotic administration was detected in three patients (2 on gentamicin, 1 on streptomycin). The degree of elevation of urinary gamma-GT activity was greater when the initial creatinine clearance was lower, and it is therefore suggested that those patients with pre-existing renal dysfunction should be monitored particularly carefully for signs of nephrotoxicity from these antibiotics. Urinary gamma-GT is a useful enzyme in the investigation of renal drug effects.

Adult↗

The changing role of the clinical microbiology laboratory director: results of a survey.

Health care reform has provided clinical microbiology laboratory directors with new responsibilities and challenges that should highlight and enhance their importance within the health care system. Results of a survey sent to directors suggest that management tasks have increased since 1990, and activities that move the director into the hospital and patient care environment underscore their value to the health care team. These activities include participation on clinical practice guidelines pathway committees and use of consultative and interpretative reports. Survey results also summarize the directors' qualifications, laboratory size, typical daily schedule, job responsibilities, hours worked, time away from the laboratory for professional purposes, and comments about one's most important functions. In summary, failure to recognize new responsibilities could result in the disappearance of the position of director as we know it. Capitalizing on this challenge will secure the microbiology director's role for decades to come.

Laboratories↗