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Biomedical subjects

P Guest

Publications and source records attributed to P Guest.

At least 19 recordsLinked to original sources
PubMed1999

Reproducibility of thoracic aortic diameter measurement using computed tomographic scans.

OBJECTIVES: Decisions to recommend elective surgical repair of thoracic aortic aneurysms (TAA) may be based on size or expansion rate, which are used as indices of the risk of rupture. Measurement error may thus affect clinical decision-making. In order to evaluate the reproducibility of aortic diameter measurements of TAA, we assessed departmental inter- and intra-observer variability of measurement of pre-selected computed tomographic scan images of aneurysmal segments of the thoracic aorta. METHODS: We compared measurements of minimum aortic diameter made by four observers in 50 pre-selected scans and at different times by two observers using a calliper method and a measurement tool within the scan. Differences in measured dimension were analysed using Wilcoxon's signed ranks test and the repeatability assessed using the method of Bland and Altman. RESULTS: There were no significant inter-observer differences among three observers but there were significant differences between another observer and two other observers (P < 0.05). No significant intra-observer differences existed. The best intra-observer repeatability was 2.25 while the worst inter-observer repeatability was 4.37. The mean and maximum difference in measurement were +/-0.88 mm and +/-8.0 mm, respectively. Variability of measurement increased with aortic diameter. CONCLUSIONS: Calliper measurement of TAA is an acceptable measurement method for surveillance of TAA but appears most accurate with a single observer. Increasing error is seen with increasing diameter which may compound error in estimation of expansion rate. Standardisation of technique is advisable for multiple observers and aortic units should adopt quality assurance protocols to minimise error.

Aortic Aneurysm, Thoracic↗
PubMed1999

A search for the evidence supporting community paediatric practice.

AIM: Controversy exists regarding the evidence base of medicine. Estimates range from 20% to 80% in various specialties, but there have been no studies in paediatrics. The aim of this study was to ascertain the evidence base for community paediatrics. METHODS: Twelve community paediatricians working in clinics and schools in Yorkshire, Manchester, Teesside, and Cheshire carried out a prospective review of consecutive clinical contacts. Evidence for diagnostic processes, prescribing, referrals, counselling/advice, and child health promotion was found by searching electronic databases. This information was critically appraised and a consensus was obtained regarding quality and whether it supported actions taken. RESULTS: Two hundred and forty-seven consultations and 1149 clinical actions were performed. Good evidence was found from a randomised controlled trial or other appropriate study for 39.9% of the 629 actions studied; convincing non-experimental evidence for 7%; inconclusive evidence for 25.4%; evidence of ineffectiveness for 0.2%; and no evidence for 27.5%. Prescribing and child health promotion activities had the highest levels of quality evidence, and counselling/advice had the lowest. CONCLUSIONS: An encouraging amount of evidence was found to support much of community paediatric practice. This study improved on previous research in other specialties because actions other than medications and surgery were included.

Child↗
PubMed1996

Homograft replacement of thoraco-abdominal aorta for a leaking mycotic aneurysm.

We report the case of a 67-year-old, diabetic patient who underwent antibiotic-preserved homograft replacement of a thoraco-abdominal segment of the aorta for leaking mycotic aneurysm. This was successful in eradicating the sepsis and no graft complication had occurred at (18 months). Follow-up with computed tomography (CT) scanning.

Aged↗
PubMed1993

Alternative approaches to pterygomaxillary separation.

Pterygoid plate fractures, resulting from the pterygomaxillary separation in a Le Fort I osteotomy, may be associated with untoward fractures that extend to the base of the skull and orbit and which can lead to rare but significant complications. Five alternative approaches to the pterygomaxillary dysjunction were studied in 50 fresh cadavers. The results of this study show that the use of a curved Obwegeser osteotome to achieve the pterygomaxillary dysjunction should be abandoned, as it leads to an unacceptably high incidence of high-level pterygoid plate fractures at, or near, the base of the skull. The best results were obtained with a Stryker micro-oscillating saw.

Adolescent↗
PubMed1993

Interventional sialography using digital imaging.

We review our results in treating 5 patients with parotid duct pathology (3 stenoses, 2 calculi), using digital subtraction imaging for sialography, and standard interventional techniques using balloon catheters. Good technical results were achieved in all 5 patients. We describe our techniques and how they were modified to overcome various difficulties.

Catheterization↗
PubMed1992

Indomethacin and postprandial gallbladder emptying.

Patients with gallstone disease commonly have impaired gallbladder emptying. To see whether non-steroidal anti-inflammatory drugs (NSAIDs) prevent gallstone formation by improving gallbladder emptying, we assessed the effect of indomethacin on postprandial emptying in healthy subjects and in patients with gallstone disease. Subjects received indomethacin 25 mg three times a day for a week and matching placebo for another week. Compared with placebo, indomethacin improved postprandial gallbladder emptying in all 7 patients with gallstone disease. This finding was not recorded in healthy subjects with normal gallbladders. The prevention of gallstone formation associated with ingestion of NSAIDs may be due mainly to a prokinetic effect on the gallbladder since there is no evidence to suggest that these drugs affect cholesterol crystal nucleation at ordinary therapeutic doses in man or animals.

Adult↗
PubMed1992

Thrombolysis of the occluded prosthetic graft with tissue-type plasminogen activator--technique, results and problems in 23 patients.

Over a 12 month period all patients but one presenting to our hospital with occluded prosthetic grafts were treated by thrombolysis using local pulsed administration of tissue-type plasminogen activator (t-PA). There were 30 interventions in 23 patients but in one patient no thrombolytic was given after aspiration of pus from the graft. Thrombolysis was attempted in the remaining 29 procedures. 22/29 (76%) of these procedures were performed by direct puncture and catheterization of the occluded graft and in a further six (21%) access was from a non-occluded femoral artery or graft. In one case the graft was accessed surgically. Supplementary angioplasties were performed in 15 cases (52%). Complications requiring surgery occurred in four (14%) with a further seven minor complications. There were no deaths. A lower rate of complications occurred in the grafts entered by direct puncture. Thrombolysis was achieved in all but one case taking an average of only 2.5 h but was only maintained beyond the end of the procedure in 21/29 (72%). An underlying cause for occlusion was identified and treated where possible, e.g. haematological or clotting abnormalities or inflow or outflow stenoses. There was a high rate of reocclusion but with repeat procedures when necessary patency was maintained in 10/22 patients (45%) on follow-up at 1 to 12 months. The best results were obtained with lysis of occluded femoro-femoral crossover grafts.

Aged↗
PubMed1992

A multiple dose comparison of combinations of ibuprofen and codeine and paracetamol, codeine and caffeine after third molar surgery.

In a randomised, double-blind, double-dummy, multiple dose, crossover study in 30 patients we compared an ibuprofen/codeine combination (400 mg ibuprofen/25.6 mg codeine phosphate) with a paracetamol/codeine/caffeine combination (1 g paracetamol/16 mg codeine phosphate/60 mg caffeine) for pain relief over 6 days after two-stage bilateral lower third molar removal. The ibuprofen combination produced significantly greater analgesia than the paracetamol combination, both on single-dose analysis of the first and second days and on multiple-dose measures for days 1, 2, 3 and 4. The mean incidence of adverse effects over the 6 days was 20% for both combinations. This trial design (crossover with multiple dosing in outpatients) is a sensitive way of testing for analgesia, and is potentially more predictive of adverse effect problems than single-dose studies. It confirms that multiple dosing may show increased efficacy.

Acetaminophen↗
PubMed1990

Multilevel models of fertility determination in four Southeast Asian countries: 1970 and 1980.

Using microdata from the 1970 and 1980 censuses, we specify and test multilevel models of fertility determination for four Southeast Asian societies--Indonesia, Peninsular Malaysia, the Philippines, and Thailand. Social context is indexed by provincial characteristics representing women's status, the roles of children, and infant mortality. These contextual variables are hypothesized to have direct and indirect (through individual socioeconomic characteristics) effects on current fertility. The contextual variables account for a modest but significant share of individual variation in fertility and about one-half of the total between area variation in fertility. The women's status contextual variables, particularly modern sector employment, have the largest and most consistent effect on lowered fertility. The results based on the other contextual variables provide mixed support for the initial hypotheses.

Adolescent↗
PubMed1989

Epithelioid hemangioendothelioma of the skin and femur.

A case of epithelioid hemangioendothelioma presenting as violaceous nodules on the skin of the thigh is described. On histologic examination the tumor exhibited a proliferation of vascular channels lined by plump cuboidal and atypical endothelial cells with an epithelioid appearance. Lesions of epithelioid hemangioendothelioma were subsequently discovered in the adjacent femur. These tumors were successfully treated with chemotherapy and irradiation followed by a limb salvage procedure. To our knowledge, cutaneous presentation of this rare tumor has not been reported previously.

Adult↗
PubMed1988

Lophotoxin and related coral toxins covalently label the alpha-subunit of the nicotinic acetylcholine receptor.

Lophotoxin and lophotoxin analog-1 are uncharged cyclic diterpenes obtained from gorgonian corals. They have been shown to block the function of nicotinic acetylcholine receptors. Inhibition results from blockade of the agonist recognition site and appears irreversible in that extensive washing does not restore receptor function. This study was undertaken to determine whether this apparently irreversible inhibition involves covalent labeling at a selective site and to further characterize this site directly. Incubation of membranes prepared from the electric organ of Torpedo californica with analog-1 followed by reduction with NaB3H4 resulted in the incorporation of radioactivity into several membrane proteins. The incorporation of radioactivity into the alpha-subunit of the receptor was blocked by prior incubation with agonists and antagonists. [3H]Lophotoxin and [3H]analog-1 were prepared by reduction with NaB3H4 and back-oxidation with CrO3. The radiolabeled coral toxins reacted selectively and covalently with the alpha-subunit of the receptor. Their binding was prevented by prior exposure to agonists and antagonists. In contrast to the site-directed alkylating agent 4-(N-maleimido)benzyltrimethylammonium iodide, prior reduction of the receptor was not required for covalent binding of 3H-labeled coral toxins. Selective reduction of Cys192 and Cys193 followed by alkylation with 4-(N-maleimido)benzyltrimethylammonium iodide blocked the binding of [3H]analog-1, whereas alkylation with iodoacetic acid or iodoacetamide did not. Thus, the binding site for the coral toxins does not overlap the binding surface near Cys192 and Cys193. Digestion of isolated labeled alpha-subunits with endoglycosidase H revealed that the polypeptide portion of the protein retained the covalently bound [3H]analog-1. Digestion with staphylococcal V8 protease revealed two major peptides of approximately 19 and 20 kDa, along with several smaller peptides. Only the 20-kDa peptide retained the covalently bound [3H]analog-1, localizing the site of covalent attachment between Ser173 and Glu335. The unique chemical structure and covalent reactivity of these gorgonian coral toxins will undoubtedly allow further insights into the structure of the agonist recognition site.

Animals↗
PubMed1985

The value of the Radial Head-Capitellum view in radial head trauma.

The value of the Radial Head-Capitellum view has been assessed in a series of 28 consecutive cases of radial head fracture. Additional useful information was obtained in 21% of cases. The Radial Head-Capitellum view may be a valuable additional view in assessing radial head trauma.

Clinical Trials as Topic↗