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Biomedical subjects

G Davies

Publications and source records attributed to G Davies.

At least 163 records · Page 9Linked to original sources

Rabies policy.

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Animals↗

The 1993 Italian foot-and-mouth disease epidemic: epidemiological features of the four outbreaks identified in Verona province (Veneto region).

Imported cattle gave rise to an epidemic of foot-and-mouth disease (FMD) in Italy during 1993. Four outbreaks occurred in large housed beef herds in Verona province. Investigations revealed that there were no movements of livestock out of the infected premises and meteorological analyses suggested that the airborne spread of infectious particles had been limited by the anticyclonic conditions. Surveillance was therefore concentrated on the areas immediately surrounding the outbreaks and the infection was prevented from spreading.

Animals↗

Credit where due.

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Authorship↗

Crystallization and preliminary X-ray analysis of Candida albicans phosphomannose isomerase.

Crystals of recombinant phosphomannose isomerase from Candida albicans have been obtained in a form suitable for X-ray diffraction analysis. The enzyme plays a key role in the biosynthesis of the mannan component of the fungal cell wall. It crystallizes in monoclinic space group C2, with cell dimensions a = 124.9 A, b = 52.9 A, c = 85.9 A and beta = 127.4 degrees. The crystals diffract to Bragg spacings beyond 1.7 A, native data have been collected to 2.4 A and a search for heavy-metal derivatives is in progress. The asymmetric unit contains one molecule of the enzyme (M(r) approximately 49,000) with a Vm of 2.3 A3/Da.

Candida albicans↗

Effects of aminophylline on cardiac function and regional myocardial perfusion: implications regarding its antiischemic action.

Aminophylline improves exercise capacity in patients with angina. Because this drug does not dilate epicardial coronary vessels, its beneficial effect is from either a reduction of myocardial oxygen consumption or an improvement of myocardial blood flow distribution. This study was performed to assess the effects of aminophylline on cardiac function and on regional myocardial perfusion to establish the mechanisms of its antiischemic action. In 10 patients during cardiac catheterization hemodynamic parameters and cardiac volumes were obtained during baseline and after intravenous infusion of aminophylline. Aminophylline decreased left ventricular end-diastolic pressure (from 11 +/- 4 to 4 +/- 2 mmHg, p < 0.001), mean right atrial pressure (from 5 +/- 2 to 2 +/- 1 mmHg, p < 0.01), and left ventricular end-diastolic volume (from 117 +/- 36 to 88 +/- 36 ml, p < 0.01); it increased peak dp/dt (from 1931 +/- 329 to 2430 +/- 540 mmHg/sec, p < 0.001) and heart rate (from 69 +/- 9 to 76 +/- 14 beats/min, p < 0.05) and did not modify systolic aortic pressure (138 +/- 14 vs 137 +/- 16 mmHg, p = not significant [NS]). Estimated oxygen consumption during aminophylline (6.7 +/- 1.3 ml/min/gm) was similar to that during baseline (6.7 +/- 1.4 ml/min/gm). In another study in nine anesthetized dogs with a critical stenosis of the left anterior descending artery, myocardial perfusion was assessed by microspheres during control atrial pacing and during atrial pacing after aminophylline; left atrial pressure was kept constant throughout the study.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminophylline↗

Left ventricular function and coronary artery disease progression early after coronary bypass grafting.

To investigate the effects of coronary artery disease progression on left ventricular function in patients who suffer angina early after coronary artery bypass grafting, we studied the progression of coronary stenoses, the occurrence of graft occlusions, and measured left ventricular ejection fraction (regional and global) in 34 consecutive patients who underwent repeat angiography 25.2 +/- 3.5 (standard error of the mean) months postoperatively, from a total population of 550 patients who underwent bypass grafting. Resting left ventricular function and stenosis severity were assessed using a computerized, quantitative analysis system. Coronary stenosis progression was defined as an increase in the percentage of the stenotic occlusion by 30% or more, any increase in lesion severity that resulted in total coronary artery occlusion, or the occurrence of a new stenosis that occluded the artery by 50% or more. Group 1 comprised 21 patients with all grafts patent and group 2 comprised 13 patients with one or more grafts occluded (20 of 34 grafts). Coronary artery disease progressed in all patients in group 1, and this involved 22 of 54 (41%) grafted vessels and 3 of 15 (20%) nongrafted vessels (p < 0.05). Coronary artery disease progressed in 11 patients in group 2, involving 15 of 32 (47%) grafted vessels and 1 of 6 (17%) nongrafted vessels (p < 0.01). An increased collateral circulation was observed in both groups. The left ventricular ejection fraction remained unchanged in both groups (group 1, 0.60 +/- 0.03 versus 0.62 +/- 0.03; group 2, 0.62 +/- 0.05 versus 0.62 +/- 0.04 before and after bypass, respectively; p = not significant) and there was no difference between the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Colour flow imaging of the normal short saphenous vein.

Colour flow imaging was used to assess the functional anatomy of the short saphenous vein (SSV) system in 104 limbs of 52 healthy volunteers. Previous studies have shown that the majority of pathological SSVs join the popliteal vein (PV) at the level of the knee. This was not the case in nearly half of the healthy limbs in this study. In these limbs the SSV retained its early embryonic function of providing venous return from the superficial system of the lower leg into veins of the upper leg and buttock. Is this a developmental safety valve?

Adult↗

Effects of ketanserin on epicardial coronary arteries after coronary angioplasty in patients with stable angina.

Previous studies have demonstrated the development of vasoconstriction immediately after percutaneous coronary angioplasty (PTCA), distal to the dilated stenosis, presumably resulting from endothelial injury. We have investigated the role of 5-HT2 receptors in mediating vasomotor changes in proximal and distal coronary segments and coronary stenoses, immediately after successful PTCA in patients with chronic stable angina. We compared the effects of the intracoronary infusion of 1 mg ketanserin (5-HT2 receptor antagonist) on proximal and distal coronary arterial segments immediately after PTCA in both vessels subjected to PTCA and control vessels. Coronary diameters, before and after angioplasty and after ketanserin administration, of proximal and distal segments and coronary stenoses were measured by computerized quantitative coronary angiography (CAAS system) in 12 patients (10 male, two female; mean age 54 +/- 6 years) with stable angina subjected to PTCA. After coronary angioplasty, vasoconstriction was observed in the segment distal to the dilated stenosis but not in the distal segments of control vessels (-0.12 +/- 0.04 and -0.02 +/- 0.02 mm respectively; P < 0.05). After ketanserin infusion significant dilatation was found in the distal segments of both PTCA vessels and control vessels, but the dilatation was greater in the PTCA vessels (P < 0.05). No significant changes were found in the proximal segments of either PTCA or control vessels, or at the PTCA site. In conclusion, the vasoconstriction distal to the site of PTCA is mediated, at least in part, via 5-HT2 receptors.

Angina Pectoris↗

Defining trauma patient subpopulations for field stabilization.

Despite several large studies, the scoop and run versus field stabilization debate in prehospital trauma care continues. It is unlikely that all trauma patients are best treated by either field stabilization or scoop and run and the most effective form of prehospital care may be dependent upon the type of injuries sustained. Studies suggest that penetrating trauma involving major vascular injury may be best treated by scoop and run since advanced life support (ALS) measures serve only to delay time to definitive surgical treatment. Conversely, patients with head injuries may benefit from rapid ALS performed on scene in order to control airway and breathing problems, and reduce intracranial pressure prior to transport. Between these two groups of patients lie those with blunt trauma in whom scoop and run may be most appropriate if there is major vascular damage or those in whom field stabilization may offer the patient a greater chance of survival if blood loss is not a life-threatening problem.

Clinical Competence↗

Splanchnic and systemic absorption of intraperitoneal insulin using a new double-tracer method.

The absorption of a bolus of intraperitoneal insulin into the splanchnic and peripheral circulations was separately assessed in dogs using an infusion of two insulin tracers (A1-[3H]insulin and B1-[3H]insulin). One tracer was infused into the superior mesenteric artery and the second into the jugular vein. Serial samples were taken before and after an injection of insulin (1 U/kg ip). Sampling was from the portal vein and the inferior vena cava. By using the principle of equivalent entry of tracer and unlabeled material, we developed two simultaneous equations for the rate of splanchnic and peripheral insulin absorption at each time point. These were solved to yield the two rates. Mean concentrations in the portal vein were approximately 25% higher than in the inferior vena cava, reflecting the splanchnic absorption. This rate accounted for almost half (51 +/- 9%) of the insulin absorbed. The remainder of the absorption was peripheral. The total recovery of intraperitoneal insulin, absorbed by either route, was 88 +/- 11%. Portal absorption peaked earlier than peripheral. Absorption by both routes was 90% complete within approximately 2 h (131 +/- 16 min). In summary, therefore, intraperitoneal insulin is rapidly and almost completely absorbed, with absorption split between the splanchnic and peripheral routes of entry.

Absorption↗

Vasoreactivity of the culprit lesion in unstable angina.

BACKGROUND: Although abnormal vasoconstriction may be involved in the pathogenesis of the acute coronary syndromes, the vasoreactivity of the lesion responsible for unstable angina (culprit lesion) has not been directly investigated. It is also unknown if enhanced vasoreactivity is found downstream to this lesion or extends to uninvolved coronary arteries. METHODS AND RESULTS: We studied seven unstable angina patients whose condition had sufficiently stabilized to allow ergometric bicycle exercise and a cold pressor test to be performed as provocative stimuli during coronary arteriography. We measured the luminal diameter of the culprit lesion, a normal-appearing distal segment, and the segment of an uninvolved coronary artery using quantitative coronary angiography. Seven stable angina patients served as controls. Antianginal medications were tapered and interrupted. The culprit lesion constricted significantly with exercise and the cold pressor test compared with a stable angina control lesion. The culprit lesion measured 1.41 +/- 0.07 mm at baseline and diminished to 1.09 +/- 0.07 mm with exercise (P = .001). It measured 1.26 +/- 0.07 mm before the cold pressor test and diminished to 1.09 +/- 0.03 mm with this test (P = .015). In contrast, the profile of the stable lesion in the stable angina control group differed significantly (P = .006). Its luminal diameter measured 1.42 +/- 0.17 mm at baseline and 1.48 +/- 0.21 mm with exercise (P = NS). It measured 1.57 +/- 0.18 mm before and 1.55 +/- 0.18 mm with the cold pressor test (P = NS). There were no significant changes to these stimuli in the uninvolved coronary artery segments in unstable angina and in the distal segments in both unstable and stable angina patients. CONCLUSIONS: This study demonstrates increased vasoreactivity of the culprit lesion in unstable angina compared with a control lesion in stable angina. The lack of an effect either in the uninvolved coronary artery or downstream to the culprit lesion suggests that systemic neurohumoral or seeding mechanisms are not operative. This abnormal vasoreactivity might predispose to, or be a marker for, the recurrence of acute ischemia at this site.

Adult↗

Case-control study of prostatic cancer in employees of the United Kingdom Atomic Energy Authority.

OBJECTIVE: To investigate the relation between risk of prostatic cancer and occupational exposures, especially to radionuclides, in employees of the United Kingdom Atomic Energy Authority. DESIGN: Case-control study of men with prostatic cancer and matched controls. Information about sociodemographic factors and exposures to radionuclides and other substances was abstracted and classified for each subject from United Kingdom Atomic Energy Authority records without knowledge of who had cancer. SUBJECTS: 136 men with prostatic cancer diagnosed between 1946 and 1986 and 404 matched controls, all employees of United Kingdom Atomic Energy Authority. MAIN OUTCOME MEASURES: Documented or possible contamination with specific radionuclides. RESULTS: Risk of prostatic cancer was significantly increased in men who were internally contaminated with or who worked in environments potentially contaminated by tritium, chromium-51, iron-59, cobalt-60, or zinc-65. Internal contamination with at least one of the five radionuclides was detected in 14 men with prostatic cancer (10%) and 12 controls (3%) (relative risk 5.32 (95% confidence interval 1.87 to 17.24). Altogether 28 men with prostatic cancer (21%) and 46 controls (11%) worked in environments potentially contaminated by at least one of the five radionuclides (relative risk 2.36 (1.26 to 4.43)); about two thirds worked at heavy water reactors (19 men with prostatic cancer and 32 controls (relative risk 2.13 (1.00 to 4.52)). Relative risk of prostatic cancer increased with increasing duration of work in places potentially contaminated by these radionuclides and with increasing level of probable contamination. Prostatic cancer was not associated with exposure to plutonium, uranium, cadmium, boron, beryllium, or organic or inorganic chemicals. CONCLUSIONS: Risk of prostatic cancer risk was increased in United Kingdom Atomic Energy Authority workers who were occupationally exposed to tritium, 51Cr, 59Fe, 60Co, or 65Zn. Exposure to these radionuclides was infrequent, and their separate effects could not be evaluated.

Adult↗

Comparison of long-term outcome after acute myocardial infarction in patients never graduated from high school with that in more educated patients. Multicenter Investigation of the Limitation of Infarct Size (MILIS).

The clinical course of 363 patients with acute myocardial infarction who did not complete high school education was compared with that of 453 who completed at least high school. Both the in-hospital and 4-year mortality rates were markedly greater for the less educated than for the more educated patients (13 vs 5% [p < 0.001], and 36 vs 17% [p < 0.001]). Adverse baseline characteristics were partially responsible for the increased in-hospital (p = 0.059 after adjustment) and long-term (p = 0.024 after adjustment) mortality. The less educated patients were not as likely to quit smoking after acute myocardial infarction as were the more educated ones (38 vs 49%; p < 0.05). Patients who continued smoking had a greater mortality than did those who quit (24 vs 15% [p < 0.05] for less educated, and 10 vs 4% [p < 0.05] for better educated). Therefore, greater effort should be directed to smoking cessation among the high-risk group of less educated patients. However, the smoking continuation was responsible for only a small portion of the mortality difference, suggesting unidentified causes of mortality, such as lack of compliance with therapy and possible social isolation. Despite the high-risk status of the less educated patients, cardiac catheterization tended not to be performed as frequently as in the more educated patients after discharge from the hospital (16 vs 21%; p < 0.06 at 6 months).

Aged↗

Crystallization and preliminary X-ray analysis of a truncated tissue metalloproteinase inhibitor delta 128-194 TIMP-2.

Crystals of an active truncated form of a human tissue metallproteinase inhibitor (delta 128-194 TIMP-2), a protein implicated in a number of diseases of the connective tissues, have been grown in a form suitable for study by X-ray diffraction analysis. Crystals grow using polyethylene glycol 600 as a precipitant and are in space group P2(1)2(1)2, with cell dimensions a = 75.28 A, b = 100.77 A, c = 31.45 A. The asymmetric unit appears to contain two molecules of delta TIMP-2 with a Vm value of 2.3 A3/dalton. The crystals diffract to Bragg-spacings beyond 2.5 A. Native data to 3.2 A have been collected and a search for heavy-metal derivatives is in progress.

Crystallization↗