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Biomedical subjects

G H Du Boulay

Publications and source records attributed to G H Du Boulay.

At least 19 recordsLinked to original sources
PubMed1991

Correlation of SEP abnormalities with brain and cervical cord MRI in multiple sclerosis.

In 31 patients with definite or suspected multiple sclerosis (MS) presenting with a cervical cord syndrome, somatosensory evoked potentials (SEPs) were recorded to median and posterior tibial nerve stimulation, using cephalic and noncephalic reference electrodes. Magnetic resonance imaging (MRI) of the brain and cervical spinal cord was performed, the latter in sagittal and axial views. SEPs were abnormal in 67.7% of patients, whereas MRI showed cervical cord lesions in 74.2% and intracranial lesions possibly involving the somatosensory pathways in 64.5% of cases. A significant correlation was found between abnormalities of cervical (N13) and cortical (N20) potentials following median nerve stimulation with Fz reference and MRI abnormalities involving the ipsilateral or posterior half of the cervical cord, but not the contralateral or anterior half. The N13 potential, recorded from the low cervical region to a supraglottal reference, was most frequently abnormal in patients with MRI lesions at C6 or C7, whereas P14, recorded from the scalp to a clavicle reference, was most often affected by lesions at Cl or the cervicomedullary junction. Abnormalities of the cortical P40 to tibial nerve stimulation were less significantly correlated with cervical MRI lesions. The latency of N20 measured from N9 at the clavicle and the absolute latency of P40 were significantly correlated with the length of MRI abnormalities in the ipsilateral cervical cord. No significant correlation was observed between SEP abnormalities and brain MRI lesions, which it was considered might possibly involve the intracranial somatosensory pathways. It was concluded that (1) the morphological lesions seen in MRI of the cervical cord usually give rise to appropriate electrophysiological deficits, but the occasional finding of a widespread MRI lesion with normal SEP suggests that myelin damage is not the only or the major factor responsible for abnormal MRI signal; and (2) 'clinically silent' lesions apparently involving the radiations and other sensory structures of the brain appear not to give rise to detectable SEP abnormalities, using the methods of the present study.

Adult↗
PubMed1983

Leukotriene D4 and the cerebral vasculature in vivo and in vitro.

The effects of leukotriene D4 (LTD4), a component of the slow reacting substance of anaphylaxis (SRS-A), and the putative SRS-A antagonist FPL 55712 were studied on cerebral arteries in vivo and in vitro. Intracarotid injection of LTD4 (1-15 nmols/kg) into the cerebral vasculature of the anaesthetised rat constricted internal and external carotid, facio-lingual and stapedial arteries for up to 40 minutes. LTD4 at 3 nmol/kg caused a slight fall in heart rate, and at 6 and 12 nmol/kg, an increase in diastolic (but not systolic) blood pressure was observed. In some experiments, constriction was followed by dilatation (possibly due to enhanced prostacyclin synthesis). FPL 55712 (0.3 to 30 nmols/kg) injected in the same manner caused both constriction and dilatation of rat cerebral arteries. In vitro experiments were performed on isolated human intracranial arteries (basilar, vertebral and Circle of Willis) obtained at autopsy, and on the isolated rat stomach fundus. LTD4 (2 x 10(-9) to 2 x 10(-7) M) caused sustained contractions of isolated human intracranial arteries. FPL 55712 (up to 4 x 10(-7) M) failed to antagonise the vasoconstrictor effects of LTD4, and higher concentrations (8 x 10(-6) to 8 x 10(-5) M) directly relaxed cerebral arteries. In contrast, FPL 55712 (2 x 10(-8) M) was a competitive antagonist of the contractile effects of LTD4 on the isolated rat fundus. This data suggests that the cerebral arterial leukotriene receptor differs from the peripheral smooth muscle receptor typified by the guinea-pig ileum and rat fundus preparations. Furthermore, leukotrienes may be involved in pathological vasoconstriction of various vascular beds after immunological reaction and trauma.

Animals↗
PubMed1981

Regional cerebral oxygen supply and utilization in dementia. A clinical and physiological study with oxygen-15 and positron tomography.

The cerebral blood flow, oxygen extraction and oxygen utilization has been measured regionally in 22 dements, and 14 aged normal volunteers. Ten demented patients were studied twice at a six-month interval from initial measurements. The use of a steady-state 15O technique and positron tomography for measuring regional cerebral blood flow, regional oxygen extraction fraction and mean cerebral oxygen utilization is discussed. The limitations of measurements are reviewed in the light of the present results and the current state of technological development in positron emission tomography is discussed. A decline in cerebral blood flow and mean cerebral oxygen utilization was correlated with increasing severity of dementia in both degenerative and vascular dements. The decline was coupled, both for the cerebral hemisphere as a whole and regionally. There was no increase in oxygen extraction ratio globally, and therefore no evidence to support the existence of a chronic ischaemic brain syndrome. Focal abnormalities in oxygen utilization were observed for both vascular and degenerative groups. In the vascular group, parietal defects were the most pronounced. Individual derangements of the regional pattern varied, reflecting the different unique patterns of ischaemic damage in these patients. In the degenerative group, parietal and temporal defects were seen in the less severe group, but a profound depression in the frontal regions with relative sparing of occipital area characterized the severe degenerative dements.

Aged↗
PubMed1980

Cerebral blood flow after surgery for recent subarachnoid haemorrhage.

243 measurements of cerebral blood flow by a noninvasive (133)Xe clearance technique have been made in 45 patients undergoing surgery for a recently ruptured cerebral aneurysm. Two groups of patients have been defined by the presence or absence of a postoperative rise in cerebral blood flow which showed a significant correlation with level of consciousness after operation.

Adolescent↗
PubMed1980

High-resolution computerized tomography of the petrous bone.

High-resolution computerized tomography (CT) has been used to investigate abnormalities of the ear and petrous bone. Congenital, traumatic, infective and neoplastic lesions have been evaluated in 30 patients with proven pathology. Some bone changes including abnormalities of the auditory ossicles have been better demonstrated than by conventional tomographic technigues, and high-resolution CT has some advantages in demonstrating both soft tissue abnormality and bone changes in the middle ear in primary neoplastic disease and secondary cholesteatoma. The absence of any practical means of taking sagittal sections with the present scanner design limits the usefulness of high resolution CT of the petrous bone, but this study has shown that the technique may now take its place as an important complementary procedure to pluridirectional tomography.

Ear Diseases↗
PubMed1979

Cerebral blood-flow and viscosity in relative polycythaemia.

Cerebral blood flow (CBF), red-cell mass, and plasma volume were measured in 39 patients with venous haematocrit values in the range 0.47--0.58. Patients with true polycythaemia were thus excluded. The 39 patients studied fell into two groups--those with a measured red-cell mass in the high-normal range and those with normal red-cell-mass values but reduced plasma-volume values (the relative-polycythaemia, low-plasma-volume group). The mean CBF was low in both the high-normal red-cell-mass (HNRCM) group (45.8 ml/100 g/min) and low-plasma-volume (LPV) group (48.8 ml/100 g/min). The haematocrit in the HNRCM group was 0.504 and in the LPV group 0.513. In a control group of subjects with a mean haematocrit of 0.421 CBF was 68.6 ml/100 g/min. Venesection was associated with a significant rise in CBF in both groups of patients--to 59.7 ml/100 g/min in the HNRCM group and 65.0 ml/100 g/min in the LPV group. Whole-blood viscosity fell significantly in both groups. Both groups demonstrated significant inverse relationships between CBF and haematocrit and between CBF and blood viscosity.

Adult↗
PubMed1979

An intravenous 133xenon clearance technique for measuring cerebral blood flow.

An intravenous 133Xe clearance technique for measuring cerebral blood flow (CBF) is described. Results obtained compared well with those using the intracarotid 133Xe technique. The reproducibility of the method was checked by repeating measurements within a few hours in 14 patients, when no significant overall change occurred, and after some days in 23 patients when a mean fall in flow of 8% was observed. CBF was measured in 52 control subjects. The mean fast component flow (Ff) was 68.6 ml/100 g/min (SD 11.3). No difference between the two hemispheres was found. Flow was confirmed to be higher anteriorly in the cerebral hemispheres. A significant inverse correlation was found between CBF and age.

Age Factors↗
PubMed1979

Multi-infarct dementia.

Fifty-two patients presenting with dementia were divided into a group in whom clinical features suggested an ischaemic basis (multi-infarct dementia) and a group in whom a primary degenerative process seemed more likely. Focal EEG changes and angiographic evidence of ischeamic areas and atheromatous disease of intracranial vessels were more common in the "ischaemic" than in the primary degenerative group. CBF was significantly reduced in the former but the regional pattern was equally distorted in the two groups. These findings strengthen the belief that the ischaemic score can identify those patients whose dementia is associated with vascular disease.

Adult↗
PubMed1979

Relationship between presence of vasoconstrictor activity in cerebrospinal fluid and time after subarachnoid haemorrhage from rupture of cerebral arterial aneurysms.

The relationship between clinical condition and vasoconstrictor factors in cerebrospinal fluid was studied in 19 patients for up to six weeks after subarachnoid haemorrhage. Vasoconstrictor activity was assayed biologically. Sixteen of 19 patients improved as vasoconstrictor activity declined; this pattern was not significantly influenced by surgery. Serial angiography was performed on three patients and a qualitative relationship was shown between arterial dilatation, clinical improvement, and reduced pharmacological activity.

Adult↗
PubMed1979

Responses of baboon cerebral and extracerebral arteries to prostacyclin and prostaglandin endoperoxide in vitro and in vivo.

The responses of baboon cerebral and extracerebral arteries to prostaglandin endoperoxide (PGH2) and prostacyclin (PGI2) were investigated on isolated arteries and in vivo by serial angiography. Both PGH2 and PGI2 could produce dose-dependent contraction or relaxation of isolated arteries. PGH2 induced relaxation was indicative of prostacyclin synthetase activity, the enzyme which converts PGH2 to PGI2. In isolated arteries tested one to four hours post mortem only the vertebral artery showed prostacyclin synthetase activity. Thus PGH2 induced contraction of cerebral arteries may be indicative of a physiological function. Vasomotor tone may in part be the result of a balance between PGH2 constriction and PGI2 dilatation. In vivo PGI2 infusion caused pronounced and prolonged dilatation of cerebral arteries, which lasted longer than the cardiovascular changes. As PGI2 is the most potent cerebral vasodilator drug tested, it may be of clinical use in the treatment of cerebral vasospasm.

Animals↗
PubMed1979

Measurement of regional cerebral blood volume using the EMI 1010 scanner.

Regional cerebral blood volume (rCBV) was measured in 14 patients with normal CT scans. An EMI CT 1010 scanner was used in combination with a computer subtraction technique. The mean CBV in the cortex was 5.0 ml/100 ml of tissue and 2.2 in the white matter. Regional differences were not significant and no difference was found between the right and left hemispheres.

Adolescent↗
PubMed1979

[Effects of nicergoline on cerebral blood flow (author's transl)].

Cerebral blood flow (CBF) was measured before and after i.v. injection of the cerebral vasodilator 10-methoxy-1,6-dimethyl-ergoline-8 beta-methanol-(5-bromonicotinate) (nicergoline, Sermion) in 13 patients with cerebrovascular disease. CBF increased in seven. The possibility is discussed that the effect of the drug in the other patients may have been masked by a fall of CBF which occurs during sequential measurement of patients at rest. Nicergoline is an alpha-adrenergic receptor blocking agent which affects cerebral blood flow by reducing cerebrovascular resistance. The present study was undertaken to assess the acute effect of the drug on cerebral blood flow and blood pressure in patients with cerebrovascular diseases.

Cerebrovascular Circulation↗
PubMed1977

Effect of nicergoline on cerebral blood flow.

Cerebral blood flow (CBF) was measured before and after intravenous injection of the cerebral vasodilator nicergoline in 13 patients with cerebrovascular disease. CBF increased in seven. The possibility that the effect of the drug in the remainder may have been masked by a fall of CBF which occurs during sequential measurement of patients at rest is discussed.

Cerebrovascular Circulation↗