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Biomedical subjects

D Russell

Publications and source records attributed to D Russell.

At least 199 records · Page 11Linked to original sources
PubMed1989

Blood velocity and regional blood flow in defined cerebral artery systems.

Cerebral artery blood velocity and regional blood flow (rCBF) were investigated in 17 normal subjects. Blood velocity was measured with 2 MHz pulsed Doppler ultrasound in the proximal segments of the middle, anterior and posterior cerebral artery (MCA, ACA, and PCA) and in the distal extracranial internal carotid artery (ICA). The rCBF in the regions of interest tentatively corresponding to the perfusion territories of these vessels was estimated using 133Xe inhalation and a rapidly rotating single photon emission computer tomograph. Concomitant capnograph recordings showed that the end-expiratory pCO2 was higher during the rCBF than during the blood velocity examinations. This differences was highly significant. While there was no significant correlation between blood velocity and rCBF when these clear differences in pCO2 were disregarded, we did find significant positive correlations when the data were normalized to a standard pCO2 (5.3 kPa) using accepted formulas. The best correlation was found for the MCA (r = 0.630, p less than 0.001) and the PCA (r = 0.73, p less than 0.001), with a lower correlation in the ACA (r = 0.49, p less than 0.01) and the ICA (r = 0.41, p less than 0.05). The estimated blood velocity (V) given rCBF = 0 was not significantly different from 0. The results support the validity of expressing the relationship between blood velocity (V) and rCBF in defined cerebral artery systems as: V = 1/60 (rCBF) T (A)-1, where A represents the area of the lumen of the vessel segment where the velocity is being measured, and T denotes the size of the brain region being perfused from this artery.

Adult↗
PubMed1989

Effect of acetazolamide on cerebral artery blood velocity and regional cerebral blood flow in normal subjects.

The effect of intravenous acetazolamide 1 g on cerebral artery blood velocity and regional blood flow (rCBF) was investigated in eight normal subjects. Blood velocity was measured with 2 MHz pulsed Doppler in the proximal segments of the middle, anterior and posterior cerebral artery (MCA, ACA, and PCA) and in the distal extracranial internal carotid artery (ICA). The rCBF in the regions of interest tentatively corresponding to the perfusion territories of these vessels was estimated using 133Xe inhalation and a rapidly rotating single photon emission computer tomograph. Both blood velocity and rCBF increased after acetazolamide. There was no significant difference between the percentage ICA blood velocity increase (22 +/- 12%) and the percentage rCBF increase in the ICA region of interest (25 +/- 9%). In the MCA, ACA, and PCA, however, blood velocity increased more (mean increase 36-42%) than the rCBF in the corresponding regions of interest (mean increase 24-26%). These differences were highly significant suggesting a direct and site specific effect of acetazolamide in narrowing the lumen of the proximal MCA, ACA, and PCA, but not of the extracranial ICA. We also propose that the effect of acetazolamide induces reciprocal changes in the extent of adjacent perfusion territories in individual brain hemispheres. Data compiled from all subjects investigated at two very different perfusion levels (before and after acetazolamide) revealed a significant positive correlation between blood velocity and rCBF.

Acetazolamide↗
PubMed1989

The effects of mental dysfunction on nursing home care.

Many of the residents of nursing homes have mental health problems. These can be expected to affect the quantity of nursing care they require. Analysis of 285 nursing home residents, most of whom had moderate behavioral problems, reveals that their mental health characteristics can be summarized in terms of three factors: cognition, affect and aggressiveness. Cognitive deficits significantly increase the quantity of basic nursing services patients require. Negative affect increases the amount of psychosocial care received. The results of the analysis are interpreted as indicating that nursing home reimbursement systems should account for moderate as well as severe mental illness.

Aged↗
PubMed1989

Ocular blood flow changes in cluster headache and chronic paroxysmal hemicrania.

Intraocular pressure and pulsatile ocular blood flow were recorded during and between attacks in patients suffering from cluster headache (n = 18) or chronic paroxysmal hemicrania (n = 7). Similarities, as well as significant differences, were observed between the two groups of patients, pointing to fundamental differences between the two disorders with regard to pathophysiology. Compared with healthy controls, the cluster headache patients demonstrated low pulsatile ocular blood flow values between attacks, with an increase to normal levels during pain. The chronic paroxysmal hemicrania patients, however, had normal values between attacks with a marked and significant increase to high values during attacks.

Adult↗
PubMed1989

Regional cerebral blood flow (rCBF) and cerebral vasoreactivity in patients with retinal ischaemic symptoms.

Regional cerebral blood flow (rCBF) and cerebral vasoreactivity were assessed in 28 consecutive patients who presented with retinal ischaemic symptoms, without clinical or cerebral CT evidence of cerebral ischaemia. rCBF was measured using xenon-133 inhalation and single photon emission computed tomography before and 20 minutes after the intravenous administration of 1 g acetazolamide. The findings suggest that patients with retinal ischaemic symptoms alone due to carotid atherosclerosis often have a carotid lesion which is of haemodynamic significance with regard to cerebral perfusion and vasoreactivity. Furthermore, localized areas with reduced cerebral perfusion may also be present in some patients, without evidence of precerebral carotid occlusive disease.

Acetazolamide↗
PubMed1989

Effect of nitroglycerin on cerebral circulation measured by transcranial Doppler and SPECT.

We used a combination of transcranial Doppler ultrasonography and single-photon emission computed tomography to noninvasively assess changes in the diameter of the middle cerebral artery induced by sublingual nitroglycerin in 10 healthy subjects. Nitroglycerin reduced mean blood flow velocities without concurrently changing regional cerebral blood flow in the perfusion territory of this vessel. Our results strongly suggest that nitroglycerin causes vasodilatation of the basal intracranial arteries.

Adult↗
PubMed1989

The modulation of fluorouracil with leucovorin in metastatic colorectal carcinoma: a prospective randomized phase III trial. Gastrointestinal Tumor Study Group.

A total of 343 patients with previously untreated metastatic measurable colorectal carcinoma were studied to evaluate the impact on toxicity, response, and survival of leucovorin-modulated fluorouracil (5-FU). A maximally tolerated intravenous bolus loading course regimen of 5-FU alone (500 mg/m2 x 5 days every 4 weeks with 25 mg/m2 escalation) was compared with a high-dose leucovorin regimen (600 mg/m2 of 5-FU with 500 mg/m2 of leucovorin weekly for 6 weeks with a 2-week rest) and with a similar low-dose leucovorin regimen (600 mg/m2 of 5-FU with 25 mg/m2 of leucovorin weekly for 6 weeks with a 2-week rest). The dose-limiting toxicity for the two 5-FU and leucovorin regimens was gastrointestinal, specifically diarrhea; severe diarrhea was seen frequently, and treatment-related toxicity was implicated in the demise of 11 of the patients (5%). Significant improvements in response rates were observed with a response rate of 33 of 109 (30.3%) on the high-dose leucovorin regimen (P less than .01 v control); 13 of 107 (12.1%) on the 5-FU control; and 21 of 112 (18.8%) on the low-dose leucovorin regimen. A trend toward longer survival in the 5-FU plus high-dose leucovorin regimen was observed. In this study, leucovorin was shown to significantly enhance the therapeutic effect of 5-FU in metastatic colorectal carcinoma.

Aged↗
PubMed1989

Is paediatrics safe in general practitioners' hands? A study in the north of England.

More than half the general practitioners in the north of England, and all the health visitors, were sent questionnaires about the primary health care of children. Eighty per cent of general practitioners responded. Their qualifications and experience in paediatrics were poor, although this was less true for younger practitioners. The doctors differed widely in their management of hypothetical clinical problems, possibly owing to this lack of training. Health visitors were thought to have an important role in developmental screening within the primary health care team, but the teamwork itself seemed weak. Although 83% of general practitioners considered developmental screening should be primarily the responsibility of the primary health care team, 31% of practices did not do it and had no plans to start. Rather more than half of the doctors in these non-screening practices would accept a clinical medical officer to screen their patients on their premises. Suggestions are made for ways of encouraging general practitioners to carry out developmental screening.

Clinical Competence↗
PubMed1989

What do health visitors contribute to the care of children? A study in the north of England.

All the health visitors in the north of England, and more than half the general practitioners, were sent questionnaires about the primary health care of children. More than 90% of the health visitors responded. Most of them took part in developmental screening and considered it primarily their responsibility; some conducted developmental or well baby clinics with no other professionals present. Clinics run by health authorities often occupied several hours per week, and were more frequently attended by health visitors than clinics run by general practitioners. Almost all the health visitors' remaining time was spent in attached practices, despite the fact that more than half said they had neither office nor clinic space of their own on practice premises. A high proportion of time was spent on clerical work; more help with this could free the health visitor to provide better developmental care for all children.

Child↗
PubMed1988

Neurological examination, computerized tomography, cerebral blood flow and neuropsychological examination in workers with long-term exposure to carbon disulfide.

Sixteen males, formerly exposed to carbon disulfide (CS2) for at least 10 years (mean 20 years), were administered a neurological examination, cerebral computerized tomography (CT), regional cerebral blood flow (rCBF) examination and neuropsychological examination. The clinical neurological examination revealed abnormalities in 15; cerebral CT showed signs of atrophy in 13; and neuropsychological examination indicated brain organic changes in 13. With the rCBF examination, slight abnormalities were found in 8. The findings indicate that long-term exposure to CS2 involves a risk of developing toxic encephalopathy, demonstrable on both neurological and neuropsychological examination. Furthermore, structural changes in the brain may be demonstrable by cerebral CT.

Brain↗
PubMed1988

Birthweight and perinatal mortality of second births conditional on weight of the first.

A woman's successive offspring tend to have similar birthweights. We use data from the Medical Birth Registry of Norway to describe weight and perinatal mortality of second births given the weight of the mother's first birth. Mean weights among second births differ by as much as 1000 grams, depending on the weight of the first. Furthermore, the survival of the second baby at any given weight is strongly affected by its weight relative to the first baby's weight. A baby may be average size compared to the whole population, but small compared to its sibling; such a baby has the increased mortality that goes with being relatively small. For example, an infant of 3250 grams is relatively large if the mother's previous baby was 2250 grams, but relatively small if the previous birth weighed 4250 grams. In the first case, the mortality risk of the 3250-gram baby is 2.2 per thousand, while in the second case, risk for the same weight infant is 9.0, or four times higher. Implications of these observations for the more general analysis of birthweight and perinatal mortality are discussed.

Birth Order↗
PubMed1988

Amaurosis fugax: clinical, Doppler and angiographic findings.

Clinical, Doppler and angiographic findings are described in 53 consecutive patients who presented with amaurosis fugax (AF) in a total of 57 eyes; 4 had non-simultaneous attacks in both eyes. Atherosclerotic lesions were detected on Doppler or angiographic (conventional arteriography and/or intravenous digital subtraction angiography) examination in 36 (63%) of the relevant precerebral internal carotid arteries (ICA) in 34 patients. Nineteen (53%) of these lesions caused a diameter reduction of more than 75%. Patient age was the most important factor in predicting the presence of relevant carotid occlusive disease, all 36 lesions being found in patients over 50 years of age. Two unusual cases of AF are described; in one AF was caused by stenosis of the ipsilateral ophthalmic artery, and in another by occlusion of the brachiocephalic artery with a steal syndrome from the right common carotid artery (CCA) to the right subclavian artery.

Adolescent↗