Search PubMed⌕ Search

Biomedical subjects

S Ferguson

Publications and source records attributed to S Ferguson.

At least 73 records · Page 4Linked to original sources
PubMed1982

Valproic acid analysis in saliva and serum using selected ion monitoring (electron ionization) of the tert.-butyldimethylsilyl derivatives.

A highly sensitive ion monitoring method for the determination of valproic acid in saliva and in serum has been developed based on the gas chromatographic--mass spectrometric analysis of the tert.-butyldimethylsilyl derivatives. Extraction methods are simple and the techniques for derivatization are rapid and convenient. Selected ion monitoring was carried out using electron ionization conditions and a common ion m/z 201 (M+--57) present in valproic acid and the internal standard octanoic acid. The lower limit of sensitivity that has acceptable precision for assay purposes is 0.1 mg/l based on a 200-microliter sample size. The ion monitoring method (derivatized) was compared to a gas chromatographic method (underivatized) for serum valproate assays and found to be essentially identical. The assay methodology was used in a kinetic study of valproic acid in two normal subjects. Saliva levels of drug were found to give reasonably good correlations with serum total and with serum free concentrations of drug in both individuals.U

Administration, Oral↗
PubMed1982

Interaction between valproic acid and aspirin in epileptic children: serum protein binding and metabolic effects.

In five of six epileptic children who were taking 18 to 49 mg/kg/day valproic acid (VPA), the steady-state serum free fractions of VPA rose from 12% to 43% when antipyretic doses of aspirin were also taken. Mean total VPA half-life (t1/2) rose from 10.4 +/- 2.7 to 12.9 +/- 1.8 hr and mean free VPA t1/2 rose from 6.7 +/- to 2.1 to 8.9 +2- 3.0 hr when salicylate was present in the serum. The in vitro albumin binding association constant (ka) for VPA was decreased by salicylate, but the in vivo ka value was not affected. The 12-hr (trough) concentrations of both free and total VPA were higher in the presence of serum salicylate in five of six patients. Renal excretion of unchanged VPA decreased in five of six patients, but the VPA carboxyl conjugate metabolite-excretion patterns were not consistently affected. Salicylate appeared to displace VPA from serum albumin in vivo, but the increased VPA t1/2 and changes in VPA elimination patterns suggest that serum salicylate also altered VPA metabolism.

Aspirin↗
PubMed1982

A two-year reject/retake profile analysis in pediatric radiology.

With increasing interest in the use of reject/retake analysis as an integral part of a routine quality assurance program in diagnostic radiology comes the need for a better understanding of the information obtained. The present study investigated the reject/retake profiles in a pediatric radiology department on a long-term basis. Retake profiles have been continually analyzed for a period of 24 months. Emphasis of the analysis were placed upon understanding the characteristics of the profiles observed and the effectiveness of the corrective actions implemented. The analysis indicated that after the implementation of a comprehensive quality assurance program, the overall rejection profile is predominantly determined by the rate of positioning errors.

Pediatrics↗
PubMed1981

Isolation of thermophilic campylobacters from two populations of dogs.

Faecal samples were collected from newly impounded stray dogs and from dogs presented to a clinic by their owners. The dogs were categorised as strays or pets and their faeces as formed or unformed. The faeces were examined bacteriologically. Campylobacters were significantly (P less than 0.01) more frequently isolated from the faeces of the stray dogs but there was no significant difference between the frequency of isolation of the organism from formed or unformed faeces. The significance of this finding in relation to public health and animal health is noted.

Animals↗
PubMed1981

Identification of the motor laryngeal nerves - a new electrical stimulation technique.

Head and neck surgeons are familiar with the technique of identifying motor nerves in the head and neck region by using electrical stimulation especially in the identification of the facial and the spinal accessory nerves. The identification of the motor laryngeal nerves by electrical stimulation intra-operatively has been described; but, the difficulty of visualization of intrinsic laryngeal muscle movement has prevented the wide spread use of this technique. This paper will introduce a simple, safe and reliable method to allow the surgeon to recognize true vocal cord movement while stimulating the recurrent laryngeal nerve. The movement of a two inch 27 gauge needle placed through the cricothyroid membrane into the ipsilateral true vocal cord permits identification of intrinsic laryngeal muscle movement during electrical stimulation of the recurrent laryngeal nerve. This method has been successfully used in confirming conductivity of the laryngeal nerve during thyroid surgery, Zenker's diverticulum surgery, cricotracheal trauma and recurrent nerve neurectomy for spasmodic dysphonia.

Electric Stimulation↗
PubMed1971

V. Pharmacology.

Explore the source record for details and available documents.

Dentistry↗
PubMedDate not supplied

The effect of guidewires during electrosurgical sphincterotomy.

We describe six electrosurgical incidents and one complication which occurred during guidewire-assisted sphincterotomy. Studies were conducted on three types of guidewires: Teflon painted, Teflon sheathed, and polymer coated. Scanning electron micrographs demonstrated surface imperfections in the painted Teflon guidewire coating, which allowed for potential electrical short circuits between cutting wire and guidewire through a septal defect in a double channel catheter. Septal defects were found in 25% (1 of the 4 tested) of the factory fresh sphincterotomes that were used in this study, and in 10% (6 of 57) of those used clinically. Induced current (capacitively coupled) present on the guidewires was measured at 13 to 30 mA for typical sphincterotomy settings. The induced current on sheathed guidewires, without any insulation defects, was measured at less than 1 mA at typical operating powers. As both short circuits and induced currents place the patient at risk for burns or perforation at the distal end of the guidewire, we suggest the use of a Teflon-sheathed rather than Teflon-painted guidewire, if the wire is to be left in place during sphincterotomy. The Teflon sheath offers the thickest insulation, a very low probability of surface defects, and therefore a high index of safety.

Aged↗
PubMedDate not supplied

Clinical and psychological correlates of lumbar motion abnormalities in low back disorders.

BACKGROUND CONTEXT: Low back pain (LBP) and low back disorders (LBDs) identify a complex constellation of conditions that frustrate both diagnosis and therapy. Dynamic quantitative assessment and questionnaire instruments directed toward psychosocial and situational variables provide potentially powerful tools for determining functional pathology and potentially outcome. PURPOSE: Our goal was to independently assess clinical correlates of a trunk motion measurement device, the lumbar motion monitor (LMM). The reliability of the LMM as a clinical test was assessed by comparison with an independent medical examination and biobehavioral questionnaires. STUDY DESIGN/SETTING: There were three study components. A multispecialty physician panel that administered a structured physical examination contributed to a clinical correlation case series study. Standardized outcomes and risk identification questionnaires were administered to the case population. Finally, the LMM was administered in a customary fashion to the same population. PATIENT SAMPLE: Nineteen subjects were recruited on the basis of criteria that included symptoms of chronic recurrent low back pain. This was an employed and active, although impaired, population. Eighteen of the subjects were currently employed with limited lost work time, but chronic and recurrent pain was a common feature. OUTCOME MEASURES: Questionnaire outcome measures were both characterologic and situation based. In addition to providing diagnoses, the physician panel was also asked to offer certain qualitative assessments, such as rehabilitative potential and functional level pertinent to activities of daily living. The impact of LMM measures on physician decision making was also assessed. Trunk angular measurements were used to assess function of patients with chronic low back disorders. METHODS: Kinematic performance on the LMM was expressed as three probability scores. These were the likelihood of abnormality, the "sincerity of effort" (exacerbation or aggravation of impairment), and the likelihood of structural anatomic disease. These variables were examined against established self-report measures of pain and disability. RESULTS: The LMM and physician panels were in agreement on the presence or absence of abnormality. LMM findings tended to be more consistent with clinical history than the clinical examination. The LMM results were also generally consistent with the self-reported measures of pain and disability: a high likelihood of structural disease was associated with depression, somatization, poor health perception and diminished vitality. CONCLUSIONS: The LMM appears to be a useful assessment tool for gauging the presence of LBP and LBD. It was accurate in detecting abnormality when abnormality was determined by clinical history and physician diagnosis. The LMM's differentiation of mechanical low back disease (nonanatomically specific disorders) from structurally specific low back disease was not consistent with a parallel clinical differentiation. Larger trials in a prospective format and studies on a chronically disabled population seem warranted. In an impaired but less disabled population, elevated pain and somatization did not appear to weaken the effort during testing.

Adult↗