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Biomedical subjects

V J Robertson

Publications and source records attributed to V J Robertson.

33 records · Page 2Linked to original sources
PubMed1996

Comparison of heating of nonliving soft tissue produced by 45 kHz and 1 MHz frequency ultrasound machines.

Ultrasound of 1 MHz frequency is used routinely for patient treatment because it can penetrate to and heat deeply located tissue. Benefits are claimed for newly introduced 45 kHz ultrasound machines, yet little evidence is available to confirm these benefits. This paper compares claims supporting the therapeutic use of 45 kHz ultrasound with those supporting the traditional MHz frequencies. The results of an empirical study comparing the heating effects are also presented. Thermocouples placed at different tissue depths in nonliving pig tissue measured temperature variations over a 40-minute period. Direct heating produced by the 45 kHz ultrasound machine was very superficial. By contrast, the 1 MHz ultrasound machine produced direct heating at all tissue depths. The results confirmed that although 45 kHz ultrasound machines may be useful for heating superficial tissues, they have limited or no use in heating deeper tissues. For treatment of deeply located tissue, 1 MHz ultrasound should continue to be used.

Hot Temperature↗
PubMed1995

Pneumocystis carinii pneumonia in Zimbabwe.

Pneumocystis carinii pneumonia (PCP) is said to be rare in Africa, with reported rates of 0-22% in human-immunodeficiency-virus (HIV) infected individuals with respiratory symptoms. Over one year in a central hospital in southern Africa, 64 HIV-infected patients with acute diffuse pneumonia unresponsive to penicillin and sputum smear-negative for acid-fast bacilli underwent fibreoptic bronchoscopy. Bronchoalveolar lavage fluid was assessed for bacteria, fungi, Pneumocystis carinii, and mycobacteria. 21 patients (33%) had PCP and 24 (39%) had tuberculosis; 6 of these had both infections. 5 patients had Kaposi's sarcoma (KS) associated with PCP, tuberculosis, or another infection, in 1 patient KS was the only finding, and in 21 no pathogen was identified. A logistic regression model was used to assess clinical, radiographic, and arterial blood gas predictors of PCP and tuberculosis. Fine reticulonodular shadowing on the chest radiograph (nodular component < 1 mm) was the strongest independent predictor of PCP (odds ratio 8.5 [95% CI 6.1-10.9]). A respiratory rate of more than 40/min was the best clinical predictor of PCP (odds ratio 11.2 [95% CI 8.8-13.6]). Median CD4+ T cell count for all cases of PCP was 134/microL (range 5-355) and for tuberculosis without PCP 206/microL (range 61-787). In resource-limited countries, a regionally appropriate management algorithm is required.

AIDS-Related Opportunistic Infections↗
PubMed1995

Subaqueous ultrasound: 45kHz and 1MHz machines compared.

This study compared the tissue heating produced by 45kHz and 1MHz ultrasound machines used subaqueously in metal and in plastic basins. An intervention study with cross-over design was used. The setting was a laboratory. Two cross-sections of nonliving pig tissue were used with thermocouples positioned, in the tissues, at different distances along the ultrasound beam axis. Specimens were each exposed subaqueously to ultrasound produced by a 45kHz machine and a 1MHz machine. Both metal and plastic treatment basins were used (2 machines x 2 basin types). Thermocouples measured temperature variations for 30 minutes with each machine on and 10 minutes with it off. Temperature increases at different tissue depths varied with both the ultrasound machine and the type of basin used. The 45kHz frequency ultrasound machine produced a maximum temperature increase of 0.4 degrees C and an initial rate of heating of 0.05 degrees C per minute. The 1MHz machine consistently produced greater temperature increases. These were further increased by 2.65 degrees C (average) if a metal rather than plastic basin was used. The 45kHz machine, operated at maximum output, produced little heating of the irradiated tissue. By contrast, the 1MHz ultrasound unit produced appreciable heating to almost the full depth of the tissue irradiated. Use of a metal basin, rather than plastic, resulted in a markedly higher maximum temperature increase and a significantly greater initial rate of heating.

Animals↗
PubMed1995

Research and the cumulation of knowledge in Physical Therapy.

BACKGROUND AND PURPOSE: Published research contributes to the knowledge base that distinguishes one discipline from another. More research is now published in the physical therapy journals, but concerns with the profession's knowledge base continue. SUBJECTS: The study examined citations from 78 clinical articles published and indexed on three thematic areas in Physical Therapy between 1951 and 1990. METHODS: Unique items and multiple-cited items were identified and counted and their sources ascertained. Linkages among multiple-cited items in each thematic area were identified and described. RESULTS: Most cited items were unique and not from the physical therapy literature. Few linkages were identified among the clinical articles. CONCLUSION AND DISCUSSION: The lack of evidence of cumulation or of coherence among the articles examined and the extent of reliance on non-physical therapy sources suggest that concerns with the knowledge base of the profession are well founded.

Forecasting↗
PubMed1995

A quantitative analysis of research in Physical Therapy.

BACKGROUND AND PURPOSE: Some physical therapists argue that research will justify and improve practice in the discipline. Whether these outcomes can be realized is partly a function of the nature of the research, the research methods used, and the extent to which clinical treatments are investigated. SUBJECTS AND METHODS: This study analyzed aspects of a sample of 272 articles published in Physical Therapy during 1954 through 1993. Each article was read and categorized according to the method used and to whether it investigated clinical treatments. RESULTS: An increasing percentage of the articles sampled described studies that used group designs, and most of the studies did not investigate clinical treatments. CONCLUSION AND DISCUSSION: These findings are paradoxical given existing criticisms of group designs and expectations in physical therapy of research. More discussions and evaluations of current research practices in physical therapy are needed.

Longitudinal Studies↗
PubMed1993

HIV and other sexually transmitted diseases at a rural hospital in Zimbabwe.

OBJECTIVE: To define the epidemiological characteristics of STD patients attending an outpatient clinic in rural Zimbabwe, to examine the aetiologic agents causing infection and to determine their relationship with HIV infection. SUBJECTS: 319 men and 146 women, making a sample of about 7% all patients attending an STD clinic during the 3 month study period. Microbiological data were collected from 104 men and 72 women selected randomly from these. Pregnant women were excluded and patients who had received antibiotics within the previous 14 days were excluded from the microbiology sub-sample. SETTING: An outpatient STD clinic at a District Hospital on a major truck route about 300 km north of the capital, Harare. METHODS: All new patients attending the clinic during a 3 month period were enrolled for clinical and epidemiological investigations using a standard procedure. Specimens for microbiological investigation were taken from every second patient seen on the first three days of each week. RESULTS: The typical patient was male (m:f ratio 2.2) aged 20-29 years (68% patients), not married (56% men) and in paid employment (66% men vs. 27% for the district). In men the most common presenting feature was genital ulceration, while in women, discharges were more common. Genital warts were noted frequently in both sexes. In the sub-sample examined microbiologically, H ducreyi was isolated from 46% ulcers clinically diagnosed as chancroid, and motile spirochaetes were detected in 25% painless ulcers. Neither of these were detected in ulcers in women, but HSV antigen was found as frequently in ulcers from men (19%) as from women (17%). In patients with genital discharges, gonococcal infection occurred in 64% men and 17% women, while T vaginalis was isolated from 39% women and only 8% men. Over 60% gonococcal isolates were PPNG, and 18% showed in vitro resistance to tetracycline. Yeasts, mainly C albicans were isolated from 42% women with a discharge and 25% women with ulcers. In men the presence of yeasts was associated with superficial ulceration and itchiness of the glans. Positive HIV-1 serology was found in 64% patients. There was no statistical association with current genital ulcers, though there was an association with previous STD episodes and particularly with serological evidence of syphilis. Apart from yeasts, there was no association between positive HIV-1 serology and the presence of pathogens in the genital tract. CONCLUSIONS: The high prevalence of HIV-1 antibodies in STD patients in Karoi suggests integration of STD and AIDS control programmes to be a necessity. Since paid employment was a common feature of both STD clinic attendance and HIV-1 seropositivity, these programmes may be effectively directed through the work place.

Adolescent↗
PubMed1993

Salmonella and shigella bacteraemia in Zimbabwe.

In patients with HIV infection, non-typhoidal salmonellae are a recognised cause of bacteraemia. This association was initially demonstrated in the United States, but has more recently been found in Kenyan patients. This prompted us to review the cases of patients with enterobacteriaceae bacteraemia admitted to Parirenyatwa Hospital, Harare. Non-typhoidal salmonella bacteraemia as compared with typhoid fever was significantly more common in HIV infected patients than in non-HIV infected patients (p < 0.01). It was also a cause of bacteraemia in patients with other immuno-suppressive conditions and in some patients without identifiable risk factors.

AIDS-Related Opportunistic Infections↗
PubMed1990

A survey of tinea capitis in primary school children in Harare, Zimbabwe.

A survey of the prevalence and appearance of tinea infections and associated dermatophytes in schools in Harare is reported. Of 704 children examined, 29% showed clinical evidence of tinea capitis; of these, 86% had mycological evidence of infection. Dermatophytes were isolated from 69% of all the specimens. The most common was Trichophyton violaceum (78% of the isolates), 9% of the dermatophytes were Microsporum audouinii, and other isolates were T. mentagrophytes, T. yaoundei, M. gypseum and M. canis.

Child↗
PubMed1989

Prospective study of human immunodeficiency virus infection and pregnancy outcomes in intravenous drug users.

To determine the effects of human immunodeficiency virus (HIV) infection on pregnancy outcomes, we prospectively studied female intravenous drug users in a methadone program in New York City. Of 191 women with HIV status known prior to pregnancy, 17 (24%) of 70 seropositives and 26 (22%) of 121 seronegatives became pregnant during 28 months of follow-up. Including 54 additional women first tested for HIV antibody after becoming pregnant, 125 pregnancies were studied in 97 women (39 seropositive, 58 seronegative). None of the seropositive pregnant women had advanced HIV-related disease at entry, and only one developed symptomatic disease (oral candidiasis) during pregnancy. No differences were observed between groups in the frequency of spontaneous or elective abortion, ectopic pregnancy, preterm delivery, stillbirth, or low-birth-weight births. Among women giving birth to live infants, seropositives were more likely than seronegatives to be hospitalized for bacterial pneumonia during pregnancy and had an increased tendency for breech presentation, although these events were infrequent. There were otherwise no differences between groups in the occurrence of antenatal, intrapartum, or neonatal complications. Results suggest that asymptomatic HIV infection is not associated with a decreased pregnancy rate or an increased risk of adverse pregnancy outcomes in intravenous drug users, and that an acceleration in HIV-disease status during pregnancy is uncommon.

Adult↗
PubMed1988

Nocardiosis: a neglected chronic lung disease in Africa?

Nocardia organisms were cultured from the sputum of 11 patients at the central hospitals in Harare, Zimbabwe, over a 12 month period. Pulmonary nocardiosis was diagnosed in one further patient on the basis of direct microscopy. Among the nine patients available for follow up, pulmonary nocardiosis was considered to be the major clinical problem in six. The patients usually presented with a chronic pulmonary infection with fever and cough without evidence of dissemination of underlying systemic disease. The chest radiograph showed consolidation in any part of the lung, and this was seen to extend slowly over several months. Prolonged diagnostic delay was a frequent problem. Haemoptysis, alcohol abuse, and empirical treatment for tuberculosis commonly featured in the history. Treatment with sulphonamides was generally successful in those patients who complied. Nocardiosis is a treatable lung disease that may be more common in developing countries than is currently recognised.

Adult↗
PubMedDate not supplied

Pulmonary diseases in patients infected with the human immunodeficiency virus in Zimbabwe, Central Africa.

During the 11 month period up to 30 September 1987, 37 patients (26 male, 11 female, mean age 27 years) with respiratory symptoms who were human immunodeficiency virus (HIV) positive, were studied prospectively on 40 occasions to determine the cause of any pulmonary complications. HIV was heterosexually transmitted. Predominant symptoms were cough (89%), fever (89%), weight loss (83%), and dyspnoea (60%). Transnasal fibre-optic bronchoscopy (with bronchoalveolar lavage, bronchial brushings and transbronchial lung biopsies) was performed on 35 patients, twice on 3 patients. 'Tru-cut' lung biopsies were obtained from 2 patients who died before bronchoscopy. Pulmonary tuberculosis was the commonest disease, being found in one-third of the patients (12 of 37). Mycobacterium tuberculosis was cultured from 4; the remainder of the plates were contaminated. Pneumocystis carinii was present in 8 patients: as the sole pathogen in 3, with Streptococcus pneumoniae in 4, Staphylococcus aureus in 2, and one also had tuberculous lymphadenitis. Endobronchial Kaposi's sarcoma was seen in 6 of 7 patients with skin nodules. Bacterial pathogens isolated included Staph. aureus (5), S. pneumoniae (5), Klebsiella pneumoniae (2), Haemophilus influenzae (2), H. parainfluenzae (1) and Pseudomonas aeruginosa (1). Invading Aspergillus fumigatus was diagnosed by lung biopsy in one. No diagnosis was reached for 8 patients. It is concluded that in Central Africa pulmonary complications in AIDS patients are similar to those in Europe and North America but the incidence of different pathogens depends on the prevalence of pathogens in the community. M. tuberculosis is probably the commonest pathogen. This study has confirmed that P. carinii pneumonia does occur, but occurs less frequently.

Adult↗
PubMedDate not supplied

Blastomycosis in Africa: clinical features, diagnosis, and treatment.

Four cases of blastomycosis seen in two acute care hospitals in Harare, Zimbabwe, are described. All patients had symptoms of at least 2 months' duration before presentation, and all had radiographic evidence of pulmonary consolidation. Three patients had confirmed bone involvement, and two had chronic discharging sinuses. The features of blastomycosis in Africa are reviewed, and problems of diagnosis and treatment are discussed. It is concluded that blastomycosis in Africa may often be misdiagnosed as tuberculosis or pyogenic infection in the absence of adequate facilities for mycologic investigation.

Adult↗
PubMedDate not supplied

Quantitative and qualitative analysis of the pressor effects of levonordefrin.

Levonordefrin, a common alternative to levoepinephrine as a vasoconstrictor in dental local anesthetic preparations, is usually used in fivefold higher concentrations, and, as such, is generally considered equivalent to epinephrine. We used anesthetized dogs that had autonomic reflexes blocked by mecamylamine to reevaluate the cardiovascular actions of intravenously administered nordefrin with respect to those of epinephrine and norepinephrine over a 100-fold dose range (0.1-10.0 micrograms/kg). Epinephrine caused a significantly greater pressor effect than nordefrin only at the highest dose studied; at low to moderate doses there was no significant difference between the two drugs. Blockade of alpha-adrenoceptors with phentolamine attenuated the peak pressor effects of all three agents. The epinephrine dose-response curve was suppressed more than the curves for norephinephrine and nordefrin, which were not significantly different from each other. Nordefrin was indistinguishable qualitatively from norepinephrine in that neither agent showed any evidence of beta 2-adrenoceptor vasodilation as seen with epinephrine. These findings suggest that nordefrin resembles norepinephrine rather than epinephrine in the receptor profile through which it produces its cardiovascular effects, and that the true potency difference between nordefrin and epinephrine with respect to pressor activity may be somewhat less than the fivefold difference commonly assumed.

Adrenergic alpha-Antagonists↗
PubMedDate not supplied

Knowledge of HIV antibody status and decisions to continue or terminate pregnancy among intravenous drug users.

We studied decisions to continue or terminate pregnancy among human immunodeficiency virus (HIV)-seropositive (+) and -seronegative (-) intravenous drug users informed of HIV antibody status before 24 weeks' gestation. Fourteen (50%) of 28 HIV+ vs 16 (44%) of 36 HIV- women chose to terminate their pregnancies. In retrospective interviews, HIV+ women were more likely to have perceived their risk of perinatal HIV transmission to be greater than or equal to 50% and, among those who terminated pregnancy, to cite this concern as an important factor in their decision. However, decisions to terminate pregnancy were predicted more readily by pregnancy-related variables such as prior elective abortion, a negative emotional reaction to pregnancy, and whether the pregnancy had been unplanned. Women who were HIV+ and chose to continue their pregnancies cited the desire for a child, religious beliefs, and family pressure as the most important factors in their decisions. Results indicate that while concerns about perinatal transmission of HIV may lead to decisions to terminate pregnancy in certain cases, there may be other determinants of pregnancy decisions in this population. Counseling of HIV-infected women must address not only perinatal transmission but also the sociocultural and behavioral context in which pregnancy decision making takes place.

Abortion, Induced↗