Biomedical subjects
W H Palmer
Publications and source records attributed to W H Palmer.
PCR-single-stranded confirmational polymorphism analysis for non-culture-based subtyping of meningococcal strains in clinical specimens.
Subspecific typing of clinical meningococcal strains is important in the investigation of outbreaks and for disease surveillance. Serogrouping, typing, and subtyping of strains currently require isolation of a meningococcus from one or more clinical specimens. However, the increasing widespread practice of preadmission administration of parenteral antibiotics has resulted in a decrease in the frequency of positive cultures obtained from blood and cerebrospinal fluid. Confirmation of meningococcal disease can be obtained by meningococcus-specific PCR from both cerebrospinal fluid (H. Ni et al., Lancet 340:1432-1434, 1992) and peripheral blood (J. Newcombe et al., J. Clin. Microbiol. 34:1637-1640, 1996) specimens. However, current PCR protocols do not yield epidemiologically useful typing information. We report here the use of PCR-single-stranded confirmational polymorphism (PCR-SSCP) analysis to amplify and type meningococcal DNA present in clinical specimens. PCR-SSCP analysis with the VR1 region of the Neisseria meningitidis porA gene as the target produced unique banding patterns for each serosubtype. Direct PCR-SSCP of clinical specimens can therefore provide typing data that can be used to investigate the epidemiology of clusters of cases and outbreaks and for disease surveillance in situations in which culture of patient specimens proves negative.
PCR of peripheral blood for diagnosis of meningococcal disease.
Meningococcal disease is normally suspected on clinical grounds and is confirmed by isolation of Neisseria meningitidis bacteria from blood or cerebrospinal fluid or, more recently, by serology or PCR of cerebrospinal fluid. Achieving confirmation of a clinical diagnosis of meningococcal disease has become more difficult in the last few years. The pre-hospitalization administration of parenteral benzylpenicillin normally renders blood cultures sterile, and lumbar puncture is undertaken less frequently, especially in young children. We evaluated PCR for the detection of meningococcal DNA in 80 blood samples taken from patients with known or suspected meningococcal disease or from patients with other diagnoses (negative controls). Both the sensitivity and the specificity of the test were 100% for patients with confirmed cases of meningococcal disease when the blood buffy coat was used (83 to 100% sensitivity and 87 to 100% specificity with 95% confidence limits). Positive PCR results could be obtained from both blood buffy coat and serum samples. Sensitivity was unaffected by prior antibiotic treatment. PCR is a rapid, sensitive test that may be used to confirm a diagnosis of meningococcal disease by using peripheral blood samples. Introduction of this test into clinical laboratories may in some cases obviate the need for lumbar puncture to be performed on patients with suspected meningococcal disease. Our results demonstrate that a substantial number of cases of meningococcal disease are not confirmed by conventional techniques and remain undiagnosed. If the PCR test described here was widely applied, the number of cases of meningococcal disease ascertained might rise by as much as 60% greater than that recognized at present. It is likely that we are in a prevaccination era for meningococcal disease. Better case ascertainment is urgently required to assess the need for vaccines, to determine their costs and benefits, and to monitor their efficacies.
An international perspective on the cholesterol debate.
For the past 5 years there has been an intensive debate and a number of conflicting guidelines suggesting what general practitioners (GPs) should do to screen and manage hyperlipidaemia. At a WONCA seminar in Vancouver in 1992, policies and guidelines from Canada, the UK, The Netherlands, New Zealand, Hong Kong and the USA were reviewed. It was concluded that cholesterol policy and guidelines tend to be influenced more by political and economic factors than by evidence of health benefit. International guidelines for cholesterol screening and management would be of minimal value, as GPs would have to interpret the epidemiological evidence of benefit from lipid screening and lipid lowering strategy in the context of each patient to arrive at optimum management.
Dissemination of guidelines on cholesterol. Effect on patterns of practice of general practitioners and family physicians in Ontario. Ontario Task Force on the Use and Provision of Medical Services.
A telephone survey of a random sample of Ontario family physicians was conducted 6 to 8 months after disseminating evidence-based guidelines for screening and managing asymptomatic hypercholesterolemia. Seventy-eight percent of respondents stated they followed these guidelines. However, specific questions revealed as few as 5% of respondents actually followed the guidelines.
Polymerase chain reaction for diagnosis of meningococcal meningitis.
Meningococcal disease is normally suspected on clinical grounds but confirmed by isolation of Neisseria meningitidis from blood or cerebrospinal fluid (CSF), or by detection of gram-negative diplococci in CSF. After parenteral antibiotics are started the isolation rate of meningococci from blood cultures drops from 50% to less than 5% and the chances of CSF being positive by culture or microscopy are also reduced. We used the polymerase chain reaction (PCR) in a blinded study to detect meningococcal DNA in 54 CSF samples from patients with meningococcal disease or from controls. The PCR primers were specific for the meningococcal insertion sequence IS1106. The sensitivity and specificity of this PCR for diagnosis of meningococcal meningitis were both 91%. Sensitivity was not affected by prior antibiotic treatment. The IS1106 PCR is a rapid and sensitive test for confirmation of the diagnosis of meningococcal meningitis.
Postgraduate training for family practice and the specialties: there are enough positions.
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Lifestyle assessment: applying microcomputers in family practice.
A randomised trial of assessment by computer was conducted with 180 patients in a family practice clinic. Histories of alcohol, tobacco, and drug use were obtained by computer (n = 60), interview (n = 60), or self completed questionnaire (n = 60). The results of previous research suggest that some patients may provide more accurate information about "sensitive" problems to a computer. No significant differences, however, in levels of consumption or problems were reported for the three methods of assessment. Patients gave differential ratings about the method of assessment, with the computer rated as more interesting but also more mechanical, cold, and impersonal. Although the interview was initially preferred by most, patients who completed the assessment by computer showed a significant increase (13% to 43%) in their preference for the computer after the assessment. The results of our study indicate that patients' acceptance of computers in family practice may be favourably influenced by direct experience with a microcomputer.
Lifestyle assessment: just asking makes a difference.
A 10 minute assessment of 180 family practice patients showed that 11% indicated a problem with drinking alcohol, 20% with cigarette smoking, 36% with consumption of coffee or tea, and 3% with non-medical drug use, while 11% wanted to discuss their use of medications. Moreover, being asked questions resulted in a twofold or threefold increase in the patients' intentions of discussing such a problem with their doctor. Although there was good overall agreement in recognising a problem between the patient and doctor, in roughly 40% of instances where the patient indicated a problem the doctor was unaware of it. These patients tended to be young, well educated, and employed in professional occupations, and were on their first visit to the doctor. Such brief assessments of lifestyle should be routinely conducted in family practice for both case finding and prevention.
The electrocardiogram in ambulatory medical practice.
The electrocardiogram is one of medicine's most frequently ordered procedures. A review of the current use of electrocardiograms in ambulatory clinical practice and the possible information that might be supplied by an electrocardiogram was undertaken. The electrocardiogram's advantages and disadvantages when used in evaluating specific cardiac disorders are discussed including the use of the electrocardiogram as a baseline. Both their values and their limitations in diagnosis and management are examined to support the authors' conclusion that electrocardiograms should be used as an adjunct to clinical diagnosis, not as a screening procedure.
The undistributd middle of medical research.
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Ventricular preexcitation syndrome. Accessory left atrioventricular connection and rhabdomyomatous myocardial fibers.
A necropsy study of the heart of a 16-year-old girl with ventricular preexcitation syndrome and supraventricular tachycardia showed an accessory left atrioventricular connection partially within the mitral valve. Both the accessory pathway and the ventricular musculature showed multiple foci of cardiac muscle fibers with rhabdomyomatous features having the characteristic appearance of rhabdomyomatosis. The case is discussed in the context of a literature review of necropsy findings in cases of ventricular preexcitation.
Effect of heart rate on coronary vascular resistance.
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Response of the left ventricle to nitroglycerin in patients with and without mitral regurgitation.
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Distribution of airway resistance with developing pulmonary edema in dogs.
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Trichromatic ear densitometer for estimation of cardiac output using indocyanine green.
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