Is the higher risk of cardiovascular disease amongst South Asian populations linked to abnormalities of haemoglobin? A preliminary case control study.

The elevated burden of cardiovascular disease (CVD) amongst South Asian populations is a complex and multi-factorial phenomenon. South Asians evolved from environments where malaria was endemic, and while haemoglobin disorders frequent this group, a link to CVD has not been described. Using a case-control feasibility study, haemoglobin abnormalities identified by mass spectrometry were compared between South Asian patients with CVD (n = 72) and non-CVD controls (n = 84).

Experimental aspects of cerebrospinal hemodynamics: the relationship between blood flow velocity waveform and cerebral autoregulation.

The dynamic relationships among mean flow velocity, its pulsatile amplitude (FVa), cortical cerebral blood flow (CBF), and cerebral perfusion pressure (CPP) were studied in normal rabbits and rabbits with subarachnoid hemorrhage using 8-MHz pulsed transcranial Doppler ultrasound and hydrogen clearance under conditions of systemic hypotension and intracranial hypertension. A two-slope relationship was observed between FVa and CPP with a break point that correlated closely with the lower limit of CBF autoregulation in each animal. Below this CPP break point, FVa varied directly with CPP, and above the break point FVa varied inversely with CPP.

Blood flow in portal systems with special reference to the rat pituitary gland.

Regional pituitary blood flow has been studied in adult female Fischer 344 rats by [14C]iodoantipyrine autoradiography. A general mathematical solution has been derived to allow the calculation of blood flow in the second compartment of a portal system and the proportion of blood "shunted" through the first compartment without exposure to tissue uptake from a knowledge of (a) the volume ratios of the two compartments, (b) the tissue tracer uptakes of the two compartments, and (c) the arterial tracer concentration with respect to time of a freely diffusible tracer. Significant diffusion limitation and/or arteriovenous shunting has been demonstrated in the neurohypophysis, suggesting that the majority of incoming blood is "shunted" unchanged to the adenohypophysis.

Changes in cerebral blood flow during anaesthesia and surgery in the sitting position.

Serial measurements of global cerebral blood flow (CBF) were made in 15 patients undergoing elective neurosurgical procedures in the sitting position, using a modified intravenous 133Xenon technique. The mean supine CBF rose from 43 (+/-3) ml/100g/min to 62 (+/-6) ml/100g/min in the sitting position and remained elevated at the end of surgery at 62 (+/-5) ml/100g/min. Both increases in CBF were statistically significant with respect to baseline supine values.

A modification of the method for the measurement of cerebral blood flow using [14C]iodoantipyrine in small animals.

We have modified the method for the measurement of cerebral blood flow using [14C]iodoantipyrine in small animals to overcome problems caused by rapid sequential arterial sampling. A second isotope, gamma-emitting [99mTc]pertechnetate, is infused together with [14C]iodoantipyrine. The 99mTc is counted externally by a detector placed over the chest.

Low-cost microcomputer-based densitometer.

We have constructed low-cost equipment for the measurement of the optical density of x-ray films. This equipment is based on a video system connected via an analog to digital converter to an Apple microcomputer. The optical density of an x-ray film can thus be accessed by commands in BASIC or machine-code programs.

Prediction of late ischaemic complications after cerebral aneurysm surgery--use of a mobile microcomputer system for the measurement of pre-, intra- and postoperative cerebral blood flow.

Patients with defective autoregulation of cerebral blood flow are at much greater risk of developing late cerebral ischaemia after intracranial aneurysm surgery. This finding was based on data derived from the intraoperative measurement of the response of the cerebral circulation to hypotension, deliberately induced to assist dissection and clipping of the aneurysm. A preoperative test which gave the same information as the intraoperative measurements might be helpful in predicting the optimal timing of aneurysm surgery.