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Biomedical subjects

G Davies

Publications and source records attributed to G Davies.

At least 109 records · Page 6Linked to original sources

Relation of von Willebrand factor to occurrence of Q waves and thrombolytic treatment in acute myocardial infarction.

We measured the changes of plasma von Willebrand factor antigen and fibrinogen levels in patients with acute myocardial infarction treated with recombinant tissue plasminogen activator and patients not given fibrinolytic drugs. The von Willebrand factor levels are greater in patients with Q-wave than in patients with non-Q-wave myocardial infarction and are independent of thrombolytic treatment. Fibrinogen levels are depressed by thrombolytic treatment but are unrelated to the presence or absence of Q waves.

Adult↗

Total serum homocysteine in senile dementia of Alzheimer type.

OBJECTIVE: The main hypothesis was that subtle vitamin B12 deficiencies occur more commonly in senile dementia of Alzheimer type (SDAT) that in healthy elderly individuals, and may be revealed by elevated total serum homocysteine (tHcy). A subsidiary hypothesis was that such deficiencies would be nutritionally independent as determined by retinol binding protein (RBP). DESIGN: A prospective case-controlled survey. SETTING: A Welsh urban psychogeriatric assessment centre and local general practice. PATIENTS: Thirty patients, aged 65 or over, seen consecutively in 1994 with features compatible with DSM-III-R criteria for primary degenerative dementia of Alzheimer type and 30 cognitively intact age-matched control subjects. MEASURES: Diagnosis was assessed using the CAMDEX. Cognitive scores were evaluated with the CAMCOG scale for patients and MMSE scores for control subjects. THcy was measured using high performance liquid chromatography (HPLC), and RBP assayed by a radial immunodiffusion method. RESULTS: Patients had a highly significant elevation of tHcy compared with control (p < 0.0001). Multiple regression highlighted the interrelated effects of tHcy and total serum cobalamin on cognitive scores. RBP did not differ between groups. Macrocytosis was absent, and neutrophil hypersegmentation uncommon, in hyperhomocysteinaemic patients. CONCLUSIONS: SDAT patients have significantly elevated tHcy. This is independent of RBP determined nutritional status. 'Classical' haematological changes of cobalamin or folate deficiency are poor predictors of tHcy in these patients. Aberrant cobalamin tissue delivery appears to contribute to SDAT cognitive decline. Relative contributions of other tHcy determinants require further investigation.

Aged↗

A comparative study of eccentric and concentric coronary stenosis vasomotion in patients with Prinzmental's variant angina and patients with stable angina pectoris.

BACKGROUND AND HYPOTHESIS: In patients with stable angina pectoris, eccentric stenoses have a greater potential for dynamic changes of caliber in response to vasoactive stimuli than concentric lesions. It is not known whether in patients with coronary artery spasm the degree of coronary vasoconstriction differs in eccentric versus concentric stenoses. Therefore, we examined the relationship between coronary stenosis morphology and the vasomotor response to vasoactive stimuli in patients with variant angina. METHODS: Computerized quantitative angiography was used to measure minimum luminal diameter of eccentric and concentric stenoses before and after the administration of ergonovine and isosorbide dinitrate in 22 patients with Prinzmetal's variant angina and in 20 patients with chronic stable angina. RESULTS: In patients with variant angina, mean stenosis diameter reduction with ergonovine was -0.85 +/- 0.38 and -1.12 +/- 0.69 mm in eccentric and concentric stenoses, respectively (p = NS). Isosorbide dinitrate promptly relieved spasm in all patients and increased the diameter of eccentric stenoses by 0.26 +/- 0.34 mm and that of concentric stenoses by 0.24 +/- 0.32 mm (p = NS). In patients with chronic stable angina, mean diameter reduction with ergonovine was -0.23 +/- 0.12 and -0.12 +/- 0.10 mm for eccentric and concentric stenoses, respectively (p < 0.05). Isosorbide dinitrate increased coronary diameter by 10% from baseline in 70% of eccentric and 38% of concentric stenoses (p < 0.01). CONCLUSION: In patients with variant angina pectoris, eccentric and concentric spastic stenoses react similarly in response to vasoactive stimuli. In patients with chronic stable angina, eccentric stenoses are more likely to show vasomotor responses than concentric stenoses.

Adult↗

"Depression" increases "craving" for sweet rewards in animal and human models of depression and craving.

This study consisted of two experiments, one in rats and one in human volunteers, that used the identical progressive ratio (PR) operant procedure. In both experiments, responding was reinforced under a progressively increasing work requirement, and different groups of subjects received reinforcers that varied in sweetness. In experiment 1, rats were subjected to chronic mild stress, a well-validated animal model of depression. Performance under the PR schedule increased in subjects reinforced with conventional precision pellets (which contain 10% sucrose) or very sweet pellets, but not in subjects reinforced with sugar-free pellets. In experiment 2, volunteers were subjected to a depressive musical mood induction. Performance under the PR schedule increased in subjects reinforced with chocolate buttons, but not in subjects reinforced with with buttons made from the relatively unpalatable chocolate substitute carob. In experiment 2, depressive mood induction also increased chocolate craving, as measured by a novel questionnaire, and there were significant correlations between chocolate craving and chocolate-reinforced PR performance. These results suggest that performance under the PR schedule provides a measure of craving rather than reward, and that craving for sweet rewards is increased by depressive mood induction in both animal and human models. Implications for the interpretation of pharmacological studies using the PR procedure are also discussed.

Adult↗

A comparison of adenosine and arbutamine for myocardial perfusion imaging.

We have compared our standard stress protocol (adenosine combined with exercise) with the new stress agent arbutamine, for thallium-201 myocardial perfusion imaging (MPI) in order to assess the comparative value of arbutamine. We studied 23 patients referred for MPI, and each patient had two studies (18 males, median age 66 years, five with previous myocardial infarction). Uptake scores were assigned to each of nine segments, and the extent and severity of defects were measured using a polar plot. Haemodynamic changes were greater with arbutamine (rate-pressure product increase 78% vs 51%, P = 0.003). Symptoms were experienced by 21 patients with arbutamine and 16 with adenosine (P = 0.07). Agreement between the techniques for classification of patients as normal or as having reversible, fixed or mixed defects was good (19 of 23 studies, 83%, kappa = 0.76). Agreement for similar classification of segments was also good (82%, kappa = 0.71). Segmental agreement for stress scores was good (86%, kappa = 0.77). However, mean size of stress defect was larger with adenosine (83+/-52 pixels vs 65+/-48 pixels, P<0.05), though severity and reversibility were similar (P = NS). We conclude that arbutamine provides comparable results to those obtained with adenosine and exercise and that the observed differences are not clinically significant.

Adenosine↗

Angiographic characteristics of infarct-related and non-infarct-related stenoses in patients in whom stable angina progressed to acute myocardial infarction.

BACKGROUND: In patients with coronary artery disease, angiographic and postmortem studies have shown that coronary stenoses in infarct-related arteries often have complex morphology. It is not known whether in patients with multivessel disease stenosis morphology in non-infarct-related arteries is different from those of the infarct-related arteries. METHODS AND RESULTS: In 24 consecutive patients we examined the angiographic characteristics of both the infarct-related stenoses and non-infarct-related stenoses before and after spontaneous acute myocardial infarction, by visual inspection and computerized edge detection of coronary angiograms. Before myocardial infarction, the severity of the infarct-related stenoses was <50% in 14 patients and > or =50% in 10 patients (p=not significant) and of non-infarct-related stenoses was <50% in 16 and > or=50% in 13. A significantly greater proportion of infarct-related stenoses with severity > or =50% progressed to non-Q-wave than to Q-wave myocardial infarction (71% vs 50%, p < 0.05). Before myocardial infarction, the percentage of concentric, eccentric, and irregular infarct-related stenoses was 8%, 13%, and 50%, respectively, whereas in the non-infarct-related stenoses it was 62%, 17%, and 21%, respectively (p < 0.01). A similar proportion of irregular morphology progressed to Q-wave or non-Q-wave myocardial infarction. CONCLUSIONS: In patients with stable angina who had acute myocardial infarction develop, the infarct-related and non-infarct-related stenoses on average are similar in severity but different in morphology. Nonsevere stenoses more frequently progress to Q-wave than to non-Q-wave myocardial infarction.

Adult↗

Simultaneous biplane first-pass radionuclide ventriculography using 99Tcm-tetrofosmin: a comparison with magnetic resonance imaging.

First-pass radionuclide ventriculography (FPRNV) using 99Tcm-labelled myocardial perfusion agents allows the assessment of myocardial function and perfusion simultaneously. We have assessed the feasibility of biplane FPRNV using 99Tcm-tetrofosmin, and have validated global and regional functional measurements by comparison with magnetic resonance imaging (MRI). FPRNV was performed at rest in 18 patients referred for assessment of known or suspected coronary artery disease (5 with previous myocardial infarction). A dual-headed camera was used to acquire RAO and LAO projections simultaneously. Left ventricular ejection fraction (LVEF) was calculated using standard methods and regional wall motion was evaluated visually in five myocardial segments using a 4-point scale and also by Fourier analysis. Cine MRI was performed in four oblique planes, LVEF was calculated using a biplane area-length method and regional motion was assessed visually in a similar fashion to FPRNV. Agreement between the techniques for LVEF was good using RAO FPRNV (mean +/- S.D. difference = 0.7 +/- 4.7%), but less good in the LAO projection (difference = 10.5 +/- 7.1%). Wall motion was normal by both FPRNV and MRI in 5 patients without CAD and 3 of the 13 patients with CAD. In the remaining 10 patients, wall motion by MRI was abnormal in 20 segments; FPRNV with visual analysis was abnormal in 8 patients (80%) and 16 (80%) segments. Fourier analysis showed regional abnormalities in 7 patients (70%) and 13 (65%) segments. There was good agreement (kappa = 0.68) between FPRNV (visual analysis) and MRI for wall motion scores, but moderate agreement (kappa = 0.55) between Fourier analysis and MRI. Thus, LVEF measured by FPRNV in the RAO projection agrees well with MRI. Normal regional wall motion is accurately identified, but regional abnormalities are better assessed with MRI.

Adult↗

Radiographic and clinical responses to periodontal therapy.

Mechanical periodontal therapy is widely used for a variety of periodontal conditions. While the clinical efficacy of this treatment has been validated, the radiographic response has not been studied in depth. The purpose of the present study was to examine the clinical and radiographic response to mechanical periodontal therapy, and assess the factors associated with these changes. One hundred and eight patients, with established periodontitis, received oral hygiene instruction and mechanical periodontal therapy for a period of 4 to 5 weeks. Scheduled maintenance visits were performed at 3, 6, 9, and 15 months. Probing depth (PD) and attachment level (AL) measurements were performed at baseline, and at 3 and 15 months. Intraoral radiographs were taken at baseline and 12 to 15 months postsurgery using a Rinn alignment system. Alveolar crestal height (ACH) measurements were performed on a pair of digitized images of the previously taken radiographs. An overall mean of patients' changes for PD, AL, and ACH was initially computed. Active sites (gainers and losers) were determined using a threshold method, and expressed as patient's percentage of active sites (number of active sites of the total sites measured in each patient). Mean overall probing reduction and AL gain was 0.5 mm and 0.44 mm, respectively. Of all sites measured, 16.6% exhibited AL gain, while only 6.2% of all sites exhibited AL loss. Mean overall change in ACH was -0.07 mm, of which 11.8% of all sites exhibited ACH gain, while 15.1% exhibited loss beyond the threshold. Non-smokers presented no change in bone loss, while smokers continued to lose bone at an annual rate of 0.17 mm, despite treatment (P <0.005). Likewise, the average percent of sites per patients showing attachment gain beyond the threshold were much greater in non-smokers (13.9%) compared to 9.0% in smokers (P <0.01). Mean probing reduction was 50% greater among non-smokers (0.6 mm) when compared to smokers (0.4 mm), which was also statistically significant (P <0.05). A positive and significant correlation was established between the percentage of sites with AL gain and sites with ACH gain (Rho =0.40; P=0.0001). It is suggested that monitoring sites for AL and ACH gain expressed as changes beyond a selective threshold is an important outcome variable in treatment studies.

Adult↗

Staff grades and associate specialists: their continuing professional development and aspirations.

A survey of staff grades and associate specialists in the Oxford deanery showed that there were slightly more females (53%). There were 44% who had on-call commitments, a third of these were first on call. Thirty-eight per cent of the staff grades and 55% of the associate specialists had membership or fellowship of their relevant Royal College. The majority undertake continuing professional development and a majority would like promotion but only a small minority is prepared to relocate to further their training.

Adult↗

Haploidentical related transplants and unrelated donor transplants with T cell addback.

Only 30% of children have a matched family donor (MFD). Alternative donors can be found from volunteer unrelated donor (UD) panels, and almost every child has a haploidentical parental donor (Haplo). The outcome of alternative donor BMT has previously been inferior due to increased graft rejection and GVHD. The recent outcome of 121 consecutive children undergoing MFD, UD, and Haplo BMT between 1994 and 1997 was analysed. [table in text] Preparative regimens for MFD/UD/Haplo BMT respectively included TBI in 30%/36%/11%, chemotherapy only in 59%/64%/89%, Campath 1G or none n 14%/ 0%/0%. The balance of GVHD and rejection was addressed by T-cell depletion (Campath 1M) in 2/71 MFD BMTs, T-cell depletion with addback of 5 x 10(4) T cells/kg on day zero in 33/41 UD BMTs, and T cell depletion of purified mobilised peripheral blood CD34+ cells and bone marrow in 9/9 Haplo BMTs. Stable engraftment was achieved in 68/71, and 35/41 (one patient after 2nd BMT) and 7/9 MFD, UD, and Haplo BMTs respectively. Median follow up, survival, disease free survival and, death rates for MFD/UD/Haplo BMT were 12/12/12 months, 74%/77%/78%, 69%/67%/67%, and 27%/23%/23% respectively. Within a wide range of paediatric diseases the outcome of alternative donor BMT now parallels that of MFD BMT.

Adolescent↗

[The 1996 epizootic of African swine fever in the Ivory Coast].

African swine fever was reported for the first time in the Côte d'Ivoire on 16 April 1996, in Abidjan. The epizootic resulted in the death of 135,000 pigs, equivalent to 29% of the pig population, of which 80% came from the commercial sector. By November, the outbreaks had stabilised and were then eliminated. All epidemiological evidence showed that the active form of disease ceased in September 1996. A variety of factors were responsible for limiting and then halting progression of the disease from the end of August 1996, including a new strategy which gave priority to local information, better control of the situation, depopulation of the infected area in Abidjan, the epidemiological containment of most cases within the villages, and also the assistance and direct involvement of the Food and Agriculture Organization (FAO) of the United Nations. The contribution of the FAO was decisive. It provided a diagnosis of the situation, recommended emergency measures, developed a control strategy, ensured the implementation of the control programme, set up a diagnostic laboratory unit and provided training for staff, slaughtered and destroyed any remaining pigs, set up and implemented a local information programme, developed and implemented a scheme for sentinel animals and for epidemiological surveillance, and designed, performed and analysed an epidemiological survey. From the commencement of the epizootic, two major shortcomings became apparent: inadequate dissemination of information, and a shortage of technical resources allocated for the control of African swine fever. These two shortcomings were compounded by other technical and socio-economic constraints.

African Swine Fever↗

Inhibition of nitric oxide synthesis during the cold pressor test in patients with coronary artery disease.

The effects of a cold pressor test during intracoronary infusions of L-NMMA and normal saline were studied in patients with chronic stable angina and in patients with normal coronary arteriograms. The cold pressor test during saline infusion caused significant dilation of proximal and distal segments in patients with normal coronary arteriograms, and this dilation was abolished by L-NMMA infusion; in patients with coronary disease the cold pressor test during saline caused constriction of the stenoses and distal segments and this constriction was augmented by L-NMMA infusion.

Aged↗