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Biomedical subjects

H S Markus

Publications and source records attributed to H S Markus.

At least 91 records · Page 5Linked to original sources
PubMed1993

Carotid endarterectomy improves haemodynamics on the contralateral side: implications for operating contralateral to an occluded carotid artery.

The importance of the patency of the contralateral carotid artery on the haemodynamic effect of a carotid stenosis was investigated. The breath-holding index was used to estimate cerebral perfusion reserve. The percentage rise in middle cerebral blood flow velocity, measured by transcranial Doppler ultrasonography, occurring during breath-holding was divided by the time of breath-holding. In study 1, ten subjects with no carotid stenosis, 13 with unilateral and eight with bilateral stenosis were studied. For unilateral stenosis the breath-holding index was reduced on the stenosed side compared with normal (0.85 versus 1.34 per cent per s, P < 0.05). For bilateral disease, in the presence of severe stenosis on the side contralateral to that being examined, even a moderate stenosis (30-50 per cent) resulted in a much greater reduction in the breath-holding index. In study 2, the breath-holding index was measured before and after carotid endarterectomy in ten patients. The index increased significantly following operation, not only on the operated side (1.31 versus 0.79 per cent per s, P < 0.01), but also on the contralateral side (1.23 versus 0.87 per cent per s, P < 0.05). In three of four patients with contralateral stenosis > 90 per cent or occlusion, operation improved the breath-holding index markedly (> 90 per cent) on the non-operated side above the stenosis or occlusion. These results demonstrate the importance of patency of the contralateral carotid artery in determining the haemodynamic effect of a carotid stenosis. In addition, operating contralateral to an occlusion may improve haemodynamic status above the occlusion. Implications in selecting patients for carotid endarterectomy are discussed.

Aged↗
PubMed1993

Increased prevalence of undernutrition in Parkinson's disease and its relationship to clinical disease parameters.

An anthropometric study was performed in 95 subjects (53 male, 42 female) with Parkinson's disease. Weight, height, triceps and biceps skin-fold thicknesses, and mid-arm circumference were recorded. A high incidence of undernutrition was found (23.6% of males and 22.5% of females, as defined by recent British guidelines). A subgroup of severely disabled patients with Parkinson's disease had a significantly lower mean body mass index than a similarly disabled control group with chronic pyramidal upper motor neuron lesions (males 20.6 v 23.2 kg/m2 p < 0.05; females 20.6 v 26.6 kg/m2 p < 0.01), suggesting that the undernutrition is not due to chronic illness or immobility alone. Correlation between anthropometric indices and clinical features of disease demonstrated that the presence of moderate or severe dyskinetic movements was the clinical parameter most strongly related to undernutrition. The reduction in anthropometric indices was most marked for skin fold thickness (related to percentage body fat) and least for arm muscle circumference (related to lean body mass); therefore the weight loss seen in Parkinson's disease is primarily due to fat loss rather than muscle loss.

Adult↗
PubMed1993

Splenic function, assessed by quantification of erythrocyte membrane pits, is normal in chronic active hepatitis and primary biliary cirrhosis.

Splenic hypofunction has been described in a number of diseases in which autoimmune mechanisms are believed to play a part. It has been reported in association with chronic active hepatitis although this relationship has not been systematically investigated. Twenty patients with chronic active hepatitis and 22 patients with primary biliary cirrhosis, together with an equal number of age-matched controls for each group, were studied. Splenic function was assessed by counting pits on erythrocytes viewed under differential interference contrast microscopy. There was no difference between splenic function in either chronic active hepatitis, or primary biliary cirrhosis, and normal controls. In both groups of patients splenic hypofunction was significantly related to age.

Adult↗
PubMed1993

Alterations in regional cerebral blood flow, with increased temporal interhemispheric asymmetries, in the normal elderly: an HMPAO SPECT study.

Single photon emission computed tomography (SPECT) with the tracer 99Tcm-hexamethylpropyleneamine oxime (HMPAO) provides images allowing semiquantitative estimation of regional cerebral blood flow (rCBF). Despite its widespread use there is little data on patterns of rCBF obtained using this tracer in normal elderly subjects, although other methods of measurement suggest a fall in cerebral blood flow with age. Furthermore, the detection of interhemispheric asymmetries on HMPAO SPECT is often used to identify areas of pathological abnormality yet there is little data on the prevalence of asymmetries in the normal elderly. An increased prevalence of asymmetries in the elderly may explain the difficulties recently reported in using functional imaging in the diagnosis of Alzheimer's dementia. Patterns of HMPAO uptake were compared in 10 young (mean age 24.9 years; range 21-34 years) and 10 elderly (mean age 74.1 years; range 70-76 years) normal subjects. Percentage interhemispheric asymmetry ratios were calculated and found to be greater in the elderly, particularly for the temporal cortex (young 0.87%, elderly 3.73%, P < 0.001). The proportion of injected HMPAO taken up by the head was 29% higher in the younger age group. Analysis of regional uptake revealed that this trend towards reduced uptake in the elderly was a global phenomenon affecting all brain regions. The increased interhemispheric asymmetries seen in the elderly imply that a higher threshold for interpreting asymmetries as abnormal must be used in the elderly, particularly for the temporal cortex.

Adult↗
PubMed1993

Differentiation between different pathological cerebral embolic materials using transcranial Doppler in an in vitro model.

BACKGROUND AND PURPOSE: The detection of circulating particulate cerebral emboli using transcranial Doppler ultrasonography has been recently reported. It has been suggested that this method might allow discrimination between different embolic materials; this would be very useful for selecting specific pharmacological treatment in individual patients. This study was designed to identify those parameters of the Doppler signal that might prove useful in discriminating between different types and sizes of particulate cerebral emboli. METHODS: An extracorporeal circuit filled with a saline/Tween solution and driven by a peristaltic pump was used. The tubing was placed in a skull in the position of the middle cerebral artery. Using transcranial Doppler ultrasound, flow was insonated via the transtemporal window. The following embolic materials of measured sizes (range of maximum dimension, 0.5-5.0 mm) were introduced into the circuit: thrombus (n = 20), platelet-rich aggregates (n = 15), atheromatous material (n = 20), and fat (n = 20). The Doppler signal was recorded during the passage of each embolus. Off-line analysis was performed to measure the maximum amplitude and duration of the signal. RESULTS: For all embolic materials there was a highly significant relation between embolus size and maximum amplitude of the Doppler signal. The closest correlation was obtained when the logarithm of maximum amplitude was used (for thrombi, r = 0.74; for platelet, r = 0.87; for atheroma, r = 0.46; and for fat, r = 0.68). The slope of the regression line differed for the different embolic materials and was significantly steeper for platelets than for atheroma (p < 0.01). Platelet emboli of maximum dimension < or = 1.5 mm resulted in a significantly lower maximum amplitude than similarly sized atheroma emboli (157 dB versus 206.7 dB, p < 0.01). For larger emboli (> 2 mm) there was little further increase in maximum amplitude with increases in embolus size. For all embolic materials there was a highly significant linear relation between embolus size and duration of the high-amplitude (> 150 dB) signal (for thrombi, r = 0.75; for platelet, r = 0.90; for atheroma, r = 0.77; and for fat, r = 0.86). CONCLUSIONS: Platelet emboli result in lower-amplitude signals, and therefore analysis of maximum amplitude may provide information on the type of embolic material. However, it may be difficult to determine whether a given signal is associated with a large platelet embolus or a small atheroma embolus. Duration of the high-amplitude signal will allow accurate estimation of the size of emboli, particularly where the emboli are all of the same material.

Blood Platelets↗
PubMed1992

Gallopamil slow release: a double blind study of twice daily versus once daily treatment in chronic stable angina.

The clinical efficacy of a new slow release preparation of the calcium antagonist gallopamil was assessed in 20 patients by diary cards and treadmill exercise tests. A single blind phase of two week periods of placebo, gallopamil 100 mg o.d. and gallopamil 100 mg b.i.d., blinded to the patient, was followed in 18 patients by a double blind comparison of gallopamil 100 mg od versus 100 mg b.i.d. Angina frequency and trinitrin consumption per week were both significantly less on high dose (2.7 and 1.7) than on low dose (5.4 and 3.4) respectively. Treadmill total exercise time was longer on high dose (523s) than low dose (449s). Other exercise test parameters showed similar improvements on high dose treatment. Gallopamil was well tolerated. PR interval correlated best with plasma gallopamil level, while exercise test parameters correlated best with the log plasma level of its major metabolite nor-gallopamil.

Adult↗
PubMed1992

rCBF abnormalities detected, and sequentially followed, by SPECT in neuro-Behçet's syndrome with normal CT and MRI imaging.

Conventional imaging with computed tomography (CT) and magnetic resonance imaging (MRI) may show abnormalities in central nervous system Behcet's syndrome but is normal in some cases. Recently in two cases positron emission tomography has shown abnormalities in blood flow and glucose metabolism far more extensive than the abnormalities seen on CT and MRI scans in the same patients. We report a patient with neuro-Behcet's syndrome presenting with headache and personality change in whom CT and MRI brain imaging was normal, but regional cerebral blood flow imaging using single photon emission tomography with the tracer HMPAO showed extensive perfusion deficits which partially reversed after 3 months of prednisolone therapy. This technique may aid the diagnosis of cerebral involvement in Behcet's syndrome, although the cause and incidence of the perfusion deficits need further evaluation.

Behcet Syndrome↗
PubMed1992

Migraine and headache in systemic lupus erythematosus and their relationship with antibodies against phospholipids.

It has been reported that migraine is common in systemic lupus erythematous (SLE) and an association with phospholipid antibodies has been suggested. The incidence of migraine and non-migrainous headache was prospectively studied in 90 patients with SLE and 90 age- and sex-matched controls. A history of migraine was commoner in SLE patients than in controls [31(34%) vs 15(16%); P less than 0.05], and the mean age of onset was higher in the SLE group (26.8 vs 17.2 years). Within the SLE group an association was found between migraine and SLE disease activity. Non-migrainous headaches were also more common (non-significant) in the SLE group, and there was a close temporal relationship between onset of both headache and SLE in many patients. Both migraine and non-migrainous headaches in SLE patients often responded to specific SLE treatment. No association was found between migraine or other headaches and antibodies to phospholipids.

Adolescent↗
PubMed1992

"Cognitive activity" monitored by non-invasive measurement of cerebral blood flow velocity and its application to the investigation of cerebral dominance.

We have developed a method of non-invasively detecting language lateralisation by measuring the increase in middle cerebral artery blood flow velocity occurring during a word association task, using transcranial Doppler ultrasonography. All exclusively right handed subjects (N = 12) showed a relative increase in left sided flow velocity during the task; mean rise was 4.04% on the left, and -0.03% on the right (p < 0.002). Left handed subjects (N = 6) showed a mixed pattern with three showing much greater increases (> 5%) in left, compared with right, hemisphere flow velocity, and three showing only small differences between left and right sides, possibly reflecting bilateral language representation. This technique offers potential not only in studying patterns of cerebral dominance, but also in studying cognitive responses to other stimuli.

Adult↗
PubMed1992

Raised resting energy expenditure in Parkinson's disease and its relationship to muscle rigidity.

1. Resting energy expenditure was measured, by indirect calorimetry, in 12 patients with Parkinson's disease and in eight healthy age-matched control subjects. In the patients with Parkinson's disease measurements were made in both the untreated state and after an injection of the dopamine agonist apomorphine (treated state). In each state muscle rigidity was recorded. 2. Resting energy expenditure was higher in patients with Parkinson's disease in both the treated and untreated states than in the control subjects. Of the patients with Parkinson's disease, seven showed no difference in resting energy expenditure between the two treatment states, whereas four showed markedly increased resting energy expenditure in the untreated state. The change in resting energy expenditure in the untreated state, as compared with the treated state, was significantly related to the development of muscle rigidity in the untreated state. 3. In Parkinson's disease, even in optimally treated patients, resting energy expenditure is raised and this may contribute to the weight loss seen in this disease. Severe muscle rigidity occurring during untreated periods results in a further increase in resting energy expenditure.

Apomorphine↗
PubMed1992

Estimation of cerebrovascular reactivity using transcranial Doppler, including the use of breath-holding as the vasodilatory stimulus.

BACKGROUND AND PURPOSE: A proportion of individuals with carotid artery stenosis show a reduced cerebrovascular reserve as measured by a reduced cerebral arterial vasodilatory response to carbon dioxide. Two methods of quantifying this vasodilatory response, using transcranial Doppler ultrasonography, have been in general use: the total range of vasodilation between hypocapnia, induced by hyperventilation, and hypercapnia induced by breathing carbon dioxide, and the response to breathing a fixed concentration of 5% carbon dioxide. We studied whether it is possible to use the rise in carbon dioxide occurring during breath-holding as the vasodilatory stimulus. METHODS: Using transcranial Doppler, cerebral reactivity to carbon dioxide was measured in 23 subjects undergoing intravenous digital subtraction angiography of their carotid arteries for symptoms of cerebrovascular disease. A breath-holding method was compared with the two previous methods, which required administration of carbon dioxide. RESULTS: All three methods gave results that correlated highly significantly with the degree of carotid stenosis, although the correlation was highest when the full vasodilatory range was measured. This method was adopted as the gold standard, and the other methods were compared with it. The breath-holding method correlated at least as well (rho = 0.67) as the 5% CO2 method (rho = 0.64). It identified a similar group of low reactors to our gold standard method, whereas the 5% CO2 method gave some discrepant results. CONCLUSIONS: The breath-holding method offers potential as a convenient, well-tolerated screening method of assessing carbon dioxide reactivity not requiring the administration of carbon dioxide, although further validation against more established methods of measuring cerebrovascular reserve is first required.

Aged↗
PubMed1992

Creutzfeldt-Jakob disease in recipients of human growth hormone in the United Kingdom: a clinical and radiographic study.

In the past 3 years there have been five further cases, in addition to one case reported in 1985, of Creutzfeldt-Jakob disease in recipients of human growth hormone in the United Kingdom. The clinical findings of two of these cases are described, demonstrating a typical presentation with a predominantly cerebellar syndrome at onset which is not commonly a presenting feature of sporadic Creutzfeldt-Jakob disease. In one case a 99mTc hexamethylpropylenamine single photon emission tomographic scan showed marked impairment of tracer uptake in the basal ganglia and cerebral cortex at a time when the clinical picture was predominantly cerebellar. This technique may be useful in early diagnosis. In the other case post mortem examination of the brain showed prominent amyloid deposition in the cerebellum, which has not been described previously in pituitary-hormone related Creutzfeldt-Jakob disease. The previously published cases of growth hormone-related Creutzfeldt-Jakob disease are reviewed and reasons for the particular clinical pattern seen are discussed.

Adult↗
PubMed1991

Impaired splenic function in elderly people.

Splenic function was assessed in subjects aged 70 years or over by counting pits in erythrocytes viewed under differential interference contrast microscopy. An increased percentage of pitted cells has previously been described after splenectomy and in medical hyposplenism. The mean percentage of erythrocytes with one or more pits was significantly higher in 40 elderly patients (3.4%) than in 40 younger patients (1.6%), confirming the results of a previous study on a Brazilian population. There was greater variability of splenic function in the elderly subjects with a subgroup with a greatly increased percentage of pitted erythrocytes. Impaired splenic function may predispose elderly patients to pneumococcal infection. This relationship deserves further study.

Adolescent↗