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Biomedical subjects

J D Beard

Publications and source records attributed to J D Beard.

At least 73 records · Page 4Linked to original sources
PubMed1995

ADH2 gene polymorphisms are determinants of alcohol pharmacokinetics.

The class I hepatic alcohol dehydrogenases (ADHs) are primarily responsible for ethanol metabolism in humans. Genetic polymorphism at the ADH2 locus results in the inheritance of isozymes of strikingly different catalytic properties. The most common ADH2 allele, ADH2*1, encodes the low K(m) isozyme subunit beta 1. The ADH2*3 allele encodes a high-activity isozyme subunit of alcohol dehydrogenase, beta 3, identified in approximately 25% of African-Americans. The Vmax of beta 3 beta 3-ADH is 30 times greater than that of the beta 1 beta 1-ADH. Therefore, we hypothesized that the rate of ethanol metabolism, an important factor in the toxicity of ethanol, in persons with beta 3-containing ADH, either beta 3 beta 3- or beta 1 beta 3-ADH, would be faster than that of persons with only beta 1 beta 1-ADH. We tested this hypothesis with ethanol administered orally to healthy, young African-Americans. Three hundred and twenty-six African-American men and women were genotyped using polymerase chain reaction amplification of their leukocyte DNA followed by hybridization with allele-specific probes. One hundred twelve volunteers, selected by genotype, received an oral dose of ethanol designed to produce a blood ethanol concentration of 80 mg/dl (0.080 g/dl), when the blood alcohol concentration-time curve was extrapolated back to time 0. Ethanol metabolic rates (beta 60s) were determined in the 112 subjects from the slope of the pseudolinear portion of the blood ethanol concentration-time curves. The mean beta 60 of African-Americans having beta 3-containing ADH isozymes had significantly faster ethanol elimination rates than those with only beta 1 beta 1-ADH isozymes. There were no significant differences in body weight, ethanol intake in the week before testing, peak breath ethanol concentration, time to peak, or volume of distribution between the genotype groups. Within each of these groups, men had lower ethanol disappearance rates than women. These results demonstrate in vivo the kinetic differences of ADH2 isozymes that may influence individual risk for the effects of ethanol.

Adult↗
PubMed1994

Percutaneous intervention for radiation damage to axillary arteries.

Radiation injury to subclavian and axillary arteries is a rare and late complication of radiotherapy. Until recently it has been treated almost exclusively by carotid-brachial bypass surgery. We report three cases who presented with severe upper limb ischaemia following previous axillary radiotherapy for breast carcinoma. One patient with an axillary artery occlusion failed angioplasty and required bypass surgery. A further patient with an axillary artery occlusion was successfully managed by the percutaneous placement of an arterial stent. The third patient with an isolated axillary artery stenosis responded to balloon angioplasty. All three patients remained asymptomatic. Percutaneous angioplasty and stent placement, where necessary, are appropriate first choice treatment for delayed radiation stenosis and occlusion in upper limb ischaemia.

Aged↗
PubMed1994

The assessment of cerebral oxygenation during carotid endarterectomy utilising near infrared spectroscopy.

Near infrared spectroscopy is a non-invasive method for continuous monitoring of tissue oxygenation. In 11 patients undergoing unilateral carotid endarterectomy, changes in cerebral oxygenation following carotid cross-clamping and declamping detected by a near infrared spectrometer were compared with corresponding changes in ipsilateral middle cerebral artery flow velocity measured by transcranial Doppler ultrasonography. Spectroscopic traces were obtained in all patients but adequate Doppler signals in only eight. Changes in cerebral haemoglobin oxygenation correlated closely (r = 0.908, p < 0.001) with changes in middle cerebral artery velocity. The near infrared spectrometer was also sensitive to the changes in cerebral haemodynamics due to intraoperative hypo- and hypertensive episodes. No evidence of cerebral intracellular hypoxia was seen and all patients made an uneventful recovery. Near infrared spectroscopy compares well with transcranial Doppler ultrasound as a monitor of cerebral function during carotid endarterectomy and may have a future role in the elucidation of cerebral perfusion and oxygenation changes following surgery.

Aged↗
PubMed1993

Intraoperative streptokinase: a useful adjunct to balloon-catheter embolectomy.

Intraoperative thrombolysis was attempted in 31 acutely ischaemic legs after operative arteriography had demonstrated residual distal thrombus or occlusion following balloon-catheter thromboembolectomy. There were 30 patients, 16 men and 14 women, aged 43-82 (median 73) years. The indication for operation was severe ischaemia with sensorimotor loss in 25 limbs, failed percutaneous thrombolysis in three and acute graft occlusion in three. A total of 21 perfemoral, 11 perpopliteal and four graft embolectomies were initially performed. Following arteriography, 100,000 units streptokinase was infused down the isolated distal arterial tree over 30 min and arteriography repeated. Complete lysis was achieved in 11 legs (35 per cent) and partial lysis in 12 (39 per cent). Additional procedures required included six operative angioplasties and six bypass grafts. After operation pedal pulses were restored in 14 limbs (45 per cent), with a viable leg in 23 cases (74 per cent) at the time of patient discharge or death. There were five wound haematomas but no evidence of systemic fibrinolysis. Four amputations were required, none in the group undergoing successful lysis, and there were seven deaths, five from cardiac disease. Arteriography after balloon-catheter embolectomy is essential to detect residual thromboembolus and intraoperative streptokinase appears to be a safe and effective way of removing this.

Adult↗
PubMed1993

Pneumatic phlebography: a possible new technique for the assessment of recurrent varicose veins.

Initial experience with a new technique, using an inflatable compression device during ascending phlebography, is described. This method is compared with standard varicography in a small series of patients with recurrent varicose veins. In this pilot study, 13 patients had 17 limbs examined by the new method and 14 limbs by varicography. Below knee perforator incompetence was demonstrated directly in all limbs by 'pneumatic phlebography'. Short-saphenous vein and mid-thigh perforator incompetence were also more frequently demonstrated. The two tests are comparable at showing recurrent or persistent connection at the groin (13 limbs, overall). With modifications of the pressure device, pneumatic phlebography may prove to be an important method of assessing recurrent varicose veins.

Adult↗
PubMed1993

The role of pulse-generated run-off, Doppler ultrasound and conventional arteriography in the assessment of patients prior to femorocrural bypass grafting.

One of the most important prerequisites prior to femorocrural bypass is the identification of a patent calf vessel. To determine the ability of three preoperative investigations to demonstrate patent distal vessels we compared preoperative conventional arteriography, Doppler ultrasound measurement of ankle systolic pressure (ASP) and pulse generated run-off (PGR). PGR and ASP both identified significantly more calf vessels than did preoperative conventional arteriography. However, only PGR had the ability to distinguish those vessels suitable for bypass grafting from those unsuitable for grafting. These results demonstrate that PGR is the investigation of choice prior to femorocrural bypass.

Aged↗
PubMed1992

Treatment of intestinal angina by percutaneous transluminal angioplasty of a superior mesenteric artery occlusion.

A 47-year-old woman with intestinal angina due to multiple visceral artery occlusions was treated surgically but suffered early thrombosis of an aorta-to-superior mesenteric artery (SMA) bypass graft and the return of her symptoms. Percutaneous transluminal angioplasty (PTA) of the occluded native origin of the SMA was successful. Three months later she is well and gaining weight. Several series of patients treated by PTA of superior mesenteric artery stenoses have been published, but to our knowledge this is the first report of the successful application of the technique to a complete SMA occlusion.

Abdominal Pain↗