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Biomedical subjects

I Mackenzie

Publications and source records attributed to I Mackenzie.

At least 19 recordsLinked to original sources

Practical screening priorities for hearing impairment among children in developing countries.

Routine screening for hearing impairment in childhood is now widespread in industrial countries, although there is considerable controversy over the most efficient techniques and procedures. In most developing countries, however, routine screening programmes for hearing impairment do not currently exist. The problems involved in implementing screening programmes in developing and industrial countries are very different, and in selecting screening procedures for a particular population the following factors have to be taken into consideration: the environmental test conditions; the availability of resources for equipment and the training of testers; the local attitudes towards disability; the level of hearing impairment that may cause handicaps; and the major types of pathology causing hearing impairment. We suggest that in developing countries children should be screened at school entry using a simple field audiometer and that the external ear be inspected for the presence of a discharge. There is an urgent need to develop reliable and simple screening procedures for infants and young children; where possible, all children should be screened for severe or significant hearing impairment before the age of 2 years. No screening should, however, be implemented until appropriate follow-up services are available.

Acoustic Impedance Tests

Human immunodeficiency virus antibodies in sera of Australian blood donors: 1985-1990.

OBJECTIVE: To describe the results of human immunodeficiency virus type 1 (HIV-1) antibody testing of blood donations in Australia. DESIGN: Blood transfusion services tabulated the number of HIV-1 antibody tests carried out on blood donations and the number of donations found to be positive, from 1985 to 1990. SETTING: All blood transfusion services in Australia. PARTICIPANTS: All donors of blood in Australia from 1 May 1985 to 31 December 1990. OUTCOME MEASURES: The proportion of blood donations found to have HIV-1 antibody, according to State or Territory, year of donation and, when available, age, sex and donation status (repeat or first-time) of the donor. RESULTS: To the end of December 1990, 5,367,970 donations had been tested for HIV-1 antibody, and 46 were found to have the antibody, giving an overall prevalence rate of 0.86 per 100,000 donations. The highest rate was recorded in New South Wales, followed by Western Australia, and four of eight Australian States and Territories reported no donors with HIV-1 antibody. There has been no clear trend with time, but the rate is about 20% higher for 1989-1990 than for 1985-1986. Of donors found to have HIV-1 antibody, 67% were male and 33% female, and 41% reported no known or potential exposure to HIV-1 other than heterosexual contact. Among blood donors in two major Australian cities, the overall prevalence of HIV antibody was higher in those who were male, younger, and first-time donors. There has been a recent increase in the number of blood donors with HIV-1 antibody who were women reporting heterosexual contact as their only potential exposure. CONCLUSION: The rate of HIV-1 antibody in Australian blood donations remains very low and shows no clear temporal trend, but specific donor characteristics define higher rates of antibody prevalence.

Adult

Hypha formation in the white-opaque transition of Candida albicans.

Cells of Candida albicans strain WO-1 and related strains switch frequently and reversibly between a white-colony-forming unit (white phase) and a gray-colony-forming unit (opaque phase). Cells in the budding white phase exhibit the usual smooth round phenotype observed in other C. albicans strains, but cells in the budding opaque phase exhibit a unique elongate shape with surface pimples or protrusions. In this study, it was demonstrated that opaque cells formed hyphae at low to negligible levels in suspension cultures but could be induced to form hyphae at high levels when anchored to the chamber wall of a perfusion chamber or to a monolayer of human skin epithelial cells. Variability in the proportion of hyphae formed between experiments appeared to be due to variability between individual opaque clones. The hyphae formed by opaque cells were morphologically identical to hyphae formed by white cells (i.e., they were devoid of pimples or protrusions and exhibited the same shape and septal locations). They also did not stain with an opaque-specific antiserum which differentially stained opaque budding cells in a punctate fashion. However, when stimulated to form buds, opaque hyphae formed opaque-shaped daughter buds, demonstrating that although they are morphologically similar to hyphae formed by white cells, they are genetically opaque.

Antigens, Fungal

Preoperative skin preparation and surgical outcome.

The use of antiseptics in surgery from Lister to the present day is described. A review of current procedures for preoperative preparation for surgery is given; and some data showing that the effect of chlorhexidine on skin flora is persistent is recorded.

Anti-Infective Agents, Local

Air gun pellet embolism.

Air gun injuries are traditionally regarded as trivial unless they penetrate vulnerable superficial organs such as the eye, and demands for tighter controls have been largely disregarded. We report a unique complication of a penetrating air gun pellet which emphasises the potential lethal capability of these weapons.

Adolescent

A dentonasal deformity.

A case of an impacted mesiodens that produced a marked nasal deformity and a deviated nasal septum is discussed.

Adult

An organ culture model for examining epidermal desquamation.

The use of organ cultures of mouse ear skin for examining mechanisms of stratum corneum shedding has been investigated. The formation and loss of stratum corneum cells was assessed by electron microscopic autoradiography and from counts of stratum corneum cell layers taken from sections of plastic-embedded specimens. Using media supplemented with cortisone, there was a linear accumulation of stratum corneum cell layers and the rate of epidermal cell formation corresponded approximately to that in vivo. Cells that accumulated at the stratum corneum surface were loose and could consistently be removed by treatment with detergent and ultrasonication indicating the persistence of shedding mechanisms in vitro.

Animals

Demonstration of actin in oral epithelial cells.

Two human sera with antibodies against smooth muscle were used to investigate the distribution of actin in moving oral epithelial cells by immunocytochemical methods. Epithelial outgrowths from explants of rat and human oral mucosa showed a constant positive staining in the peripheral parts of the marginal cells but not in the more central parts of the epithelial sheet. This is in agreement with theories of the importance of the marginal cells in the migratory behavior of the epithelial outgrowth. Subcultured epithelial cells from the human explants showed positive staining of fine fibers in the cytoplasm. During healing of experimental oral wounds from humans and monkeys actin fibers could be demonstrated in only one of 18 cases in the epithelial cells adjacent to the wound, though positive staining of various cells was seen in the underlying tissue. This is in contrast to the evidence presented in previous studies of cells taking part in the re-epithelialization process.

Actins

Long term cimetidine in the management of severe duodenal ulcer dyspepsia.

Sixty patients who had been referred for elective ulcer surgery, and in whom a remission had been induced, entered a prospective double blind controlled trial of a single daily dose of 400 mg of cimetidine given at bedtime, or placebo. Eighty per cent of patients receiving placebo suffered symptomatic relapse and recurrence of duodenal ulceration at endoscopy within 6 months. The mean interval to relapse was 10 weeks. On the other hand, only 27 percent of patients had a recurrence during the 6-month period on low dose cimetidine therapy. No significant toxic or other side effects which could be attributed to the drug were observed.

Adult

Structural deterioration in Celestin tubes.

Two cases are described where, after 2 years, a nylon-latex Celestin tube which was left in situ to bypass a benign stricture underwent structural deterioration and produced complications requiring tube replacement. It is recommended that an alternative endo-oesophageal tube should be considered where a lifespan of this order is contemplated.

Esophageal Stenosis

Selective loss of blood group antigens during wound healing.

Frozen sections of healing wounds of the oral mucosa of 3 rhesus monkeys were examined by a double layer immunofluorescent technic for the presence of blood B-like antigens. Antigen activity was present in normal epithelium and in the epithelial outgrowth into the wounds but was absent from the outgrowth following treatment with lipid solvents. This finding suggests that glycoprotein but not glycolipid associated antigen is lost from the surface of epithelial cells during wound healing, a pattern of selective loss which may reflect a difference between regenerative and neoplastic lesions.

Animals

Condylotomy. A clinical and experimental appraisal of a surgical technique.

211 cases of temporomandibular joint pain/dysfunction syndrome treated by condylotomy were traced. 172 operations were investigated by questionnaire and 119 patients examined clinically and radiographically. Operated patients constituted less than 3% of all patients with the syndrome. 91% were cured or improved by surgery. The anatomical structure involved in the technique and operative complications, are discussed. Principal effects of surgery were to produce an increase in radiographic joint space and shortening of the ramus with minimal long term change in the position of the condylar head from its postoperative position. The clinical findings as regards remodelling were confirmed and investigated histologically in a primate model. The mechanisms of pain production in the temporomandibular joint pain/dysfunction syndrome are discussed.

Animals