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Biomedical subjects

R Stoner

Publications and source records attributed to R Stoner.

13 recordsLinked to original sources
PubMed1990

Testing for isoniazid. An evaluation of the Arkansas method.

To better treat and eliminate tuberculosis, patient compliance must be improved. Compliance can be evaluated by measuring a drug or its metabolite in the urine. In Arkansas, a simple colorimetric method of checking the urine for isoniazid (the Potts-Cozart test) has been used for many years, but it is relatively unknown outside that state and its reliability has not been confirmed. To evaluate this test, urine was blindly tested from patients from a tuberculosis clinic. Controls included urine from patients from a substance abuse clinic and Veterans Medical Center. In more than 200 urine samples tested, no false-positives were found. Urinalysis showed normal values for three patients who were supposed to be receiving antituberculosis medication, but it is likely that these patients were noncompliant. A peculiarity of the test was that the color change with positive tests varied. To investigate this variation, absorption spectroscopy of many substances was performed. Nicotine accounted for the different shade of blue associated with the positive test, but the color produced and the absorption spectroscopy were different from isoniazid, so it did not confuse the interpretation of the results. This test for isoniazid in the urine is simple, quick, inexpensive, easy to interpret, and reliable. It also can be used to detect nicotine and its metabolites.

Arkansas↗
PubMed1989

Ventricular fibrillation during rectal examination.

The case of a 74-year-old man who developed ventricular fibrillation during a digital rectal examination is presented. The patient was subsequently resuscitated and developed cardiac enzyme elevation without ECG changes, indicating a nontransmural myocardial infarction. Although controlled studies have not shown any ill effects of rectal examination in patients with acute myocardial infarction, there have been multiple case reports of bradycardia, ectopy, and ventricular arrhythmias resulting from rectal examination. The postulated etiology of the ectopy is twofold; increased vagal tone from rectal parasympathetic innervation or increased sympathetic tone from anxiety-stimulated catecholamine release. Rectal examination is definitely indicated in a subset of patients including those with gastrointestinal or genitourinary complaints, unexplained hypotension or anemia, trauma, and neurological deficits, and those who will receive anticoagulation or thrombolytic therapy. In the remaining patients, the decision must be made on a case-by-case basis. Awareness of and precautions for possible ill effects of the examination are prudent.

Aged↗
PubMed1981

Evaluation of the safety of storage medium for corneal transplants.

The results of 27 keratoplasties done at the Royal Adelaide Hospital were analysed. The success rate of the graft was similar whether storage was as whole eyes (60%) or corneo-scleral rims (65%). A modified McCarey-Kaufman medium has been used for 2 years to store the corneo-scleral rims. Phenol red has been added as an indicator of pH change and probable bacterial contamination. Laboratory experiments contaminating this medium with potential pathogens have shown that the indicator is valueless for this purpose. Several antibiotics, alone and in combination, and at varying temperatures of storage, were tested in experiments. None could be relied on to sterilise the media of the inoculated bacteria. Whole eyes are stored in moist chambers containing normal saline with penicillin plus streptomycin which is less able to support bacterial growth. Similar challenge experiments showed that normal saline is not sterilised by the penicillin plus streptomycin.

Bacterial Infections↗