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The UK government has recognised the vital contribution that the construction industry has to play in contributing towards sustainable development. While the issue of hardened concrete waste has received considerable attention, process waste arising from the manufacture of ready-mixed concrete is relatively unexplored. It is apparent that initiatives such as the landfill tax have encouraged UK ready-mixed concrete manufacturers to reduce substantially the amount of waste they produce. Environmental pressures continue to increase and ready-mixed concrete producers are being forced towards a closed loop production system.

10 patients with typical exertional angina pectoris took part in a double-blind cross-over study comparing the effects of intravenous alprenolol and placebo on exercise tolerance. — After a dose of 0.1 mg/kg of alprenolol, exercise tachycardia after 4 minutes exercise on a fixed work load was reduced by 15%, indicating adrenergic β-receptor blockade. — After alprenolol, the time of onset of pain was delayed, total working time was prolonged and total work performed increased significantly. Ischemic ECG changes were less marked in the majority of patients and disappearance time of abnormal ECG changes after work was shortened significantly.

Intravenous administration of the beta-adrenergic blocking drug, alprenolol, to a group of patients with severe obstructive disease of the airways caused no deterioration of symptoms and a clinically insignificant fall in FEV1 in the majority. A minor reduction in PaO2 occurred which suggests that alprenolol may cause local hypoventilation and/or pulmonary arteriovenous shunting. The presence of obstructive disease of the airways does not seem to pose an absolute contraindication to the use of alprenolol, although caution must be exercised in its use in such patients.

A case is presented, believed to be the first reported, describing recurrent myocardial infarction in an athletic 25-year-old man due to coronary arterial spasm, which was demonstrated at autopsy. A previous angiogram performed during life, after the first myocardial infarction, showed normal coronary arteries. The findings in this case are discussed with a review of the current knowledge pertaining to coronary arterial spasm.

Case Report The patient was a previously healthy 39-year-old housewife. She was not taking oral contraceptives. On 29th October, 1964, she awoke with a right hemiparesis and was admitted to hospital some hours later. On examination she showed weakness of the right face, arn and leg, a right Babinski response, and total right hemianaesthesia. (BP 150/80 mm. Hg., pulse rate 90, in sinus rhythm. There were no abnormal signs elsewhere in the body. Rectal and vaginal examinations were negative. Investigations: Hb 78%, WBC 5,600/cu. mm., normal differential count. ESR (Westergren) 10 mm/ hr. Serum Na 132, K 4.1, Cl 92 m.Eq/l. Blood urea 32, cholesterol, 187 mg/100 ml., (DSF: normal pressure with a free rise and fall, 41 lymphocyte/ cu. mm., protein 25 mg/ 100 ml. WR and Kahn negative. Skull and chest X-rays normal. ECG normal. On 9th November, 1964, she developed a total left hemiplegia with aphasia and increased involvement of the right side, no pyrexia or cardiac murmurs. Bilateral carotid angiograms (Fig. I) showed occlusion of the right middle cerebral artery 1 cm. beyond its origin, the left posterior parietal artery, and the angular branches of the left middle cerebral artery. There was an anastomotic supply from the anterior cerebral arteries. No evidence of atherosclerosis. Phenindione therapy was commenced. A glucose tolerance test showed a definite diabetic curve: FBS [10, I hr., 190, 1 hr., 240, 11 hr., 230, 2 hr. 200 mg/'l00 ml. On 26th November, 1964, she developed sudden dvspnoea and right pleuritic pain. The left calf was slightly tender. Chest X-ray showed bilateral diffuse nodular shadowing coalescent in the midzones, probably due to multiple pulmonary infarcts. At this time anticoagulant therapy was thought adequate from estimations of rprothromrbin times. On 3rd December, 11964, gross swelling of the left thigh and leg developed suggesting extension of the deep vein thrombosis. Intravenous heparin therapy (40,000 units/day) was started. E. L. JoNEs, M.B., Ch.B.