Search PubMed⌕ Search

Biomedical subjects

R W Russell

Publications and source records attributed to R W Russell.

At least 109 records · Page 6Linked to original sources
PubMed1979

Cardiovascular disease in patients with retinal arterial occlusion.

103 patients with retinal-artery occlusion causing permanent visual-field defect were examined clinically and angiographically to assess the extent of cardiovascular disease. The 68 patients with branch-artery occlusion had a higher prevalence of previous transient episodes, ischaemic and valvular heart-disease, and more often had an operable lesion in the carotid artery than had the 35 patients with central-artery occlusion who were more often hypertensive, had fewer warning attacks, a greater prevalence of complete carotid occlusion, and fewer operable carotid lesions. The two types of retinal vascular occlusion show aetiological differences; branch occlusion is more often embolic and should be fully investigated for carotid and cardiac disease. These measures are less often of practical importance in patients with central-artery occlusion.

Adult↗
PubMed1979

Development of behavioral tolerance: a search for subcellular mechanisms.

Development of behavioral tolerance is one of the processes by which living organisms adjust to changes in their internal and external environments. The search for neurochemical mechanisms underlying such processes requires the testing of many hypotheses. The present study was designed to examine the possible involvement of certain subcellular events. The concentrations of acetylcholine (ACh) and choline (Ch), the high-affinity transport of Ch, and the rate of synthesis of ACh were measured in synaptosomes prepared from the brains of rats. The assays were made at critical times during the acute changes in behavior induced by administration of the anticholinesterase, di-isopropylfluorophosphate, and during the development of behavioral tolerance to this compound as chronicity of administration continued. No statistically significant differences were found among treatment groups in the total concentration of ACh or Ch, the synthesis of ACh, or the high-affinity transport of Ch. These results, plus evidence from previous experiments, indicate that the development of behavioral tolerance does not relate to the factors studied. Consequently, alternative mechanisms should be considered. In addition to changes in cholinergic (muscarinic) receptors already shown to occur concomitantly with the development of behavioral tolerance, it is suggested that the possible involvement of mechanisms controlling release of ACh should be studied.

Acetylcholine↗
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

Correlation of CAT scan and visual field defects in vascular lesions of the posterior visual pathways.

Thirty-nine patients with various types of isolated homonymous hemianopias resulting from ischaemic lesions in the posterior parts of the cerebral hemisphere was examined by CAT scanning. Most had localised low density lesions withing the distribution of the posterior cerebral artery. The location of the lesion (deduced from a separate anatomical study of postmortem brain cut in the plane of the CAT scanner) was correlated with visual field defects. Lesions giving rise to quadrantic defects were smaller than those causing total hemianopias; lower quadrantic defects tended to occur in superior cuts and vice versa. Macular sparing was associated with survival of the occipital pole in some instances. Bilateral cases had a higher prevalence of associated defects.

Adult↗
PubMed1978

Some behavioral effects of suppressing choline transport by cerebroventricular injection of hemicholinium-3.

Evidence supports the proposition that the high affinity Ch uptake system associated with cholinergic nerve terminals can be the rate limiting step in the synthesis of the neurotransmitter, acetylcholine. The present experiment was designed to test the hypothesis that variations of the system would be reflected selectively in changes of conditioned avoidance behavior. HC-3, which primarily affects the high affinity component of Ch transport thus reducing endogenous levels of ACh and the synthetic capacity of cholinergic nerve terminals, was administered cerebroventricularly at 5 doses ranging from 0.0 (saline control) to 10.0 microgram. Whole brain ACh levels determined by GCMS analysis following microwave fixation ranged from 25.0 to 5.0 nmol/g-1. Trend analyses demonstrate a precise dose dependent relation between neurochemical and behavioral variables: median trials to condition increased as ACh level decreased. More detailed analyses of the results lead to the interpretation that suppression of high affinity Ch transport in brain is associated with deficiencies in the use of information and not with sensory input and storage nor with motor output.

Animals↗
PubMed1978

The recognition and prevention of border zone cerebral ischaemia during cardiac surgery.

Four patients who sustained bilateral occipital and parietal lobe ischaemia during cardiac surgery for coronary artery bypass are described. The features include cortical blindness, visual disorientation, disturbances of reading and constructional dyspraxia. The symptoms tended to improve over about six weeks and good visual acuity was regained in all instances. The likeliest cause is generalized cerebral hypotension. Ischaemic injury might be prevented by prior detection of extracranial arterial disease and by monitoring cerebral as well as cardiac activity during surgery.

Adult↗
PubMed1977

Effect of haematocrit on cerebral blood-flow in man.

Cerebral blood-flow (C.B.F.) was measured in 38 patients with haematocrit values (Hct) in the range 0-47--0-53 and was found to be significantly lower than in 43 patients with Hct in a lower range (0-36--0-46). After reduction of Hct in the higher Hct group by venesection, flow increased by a mean of 50%. This improvement in flow was largely due to a reduction in viscosity. Hct around the generally accepted upper limit of normal may be an important factor in the causation of occlusive vascular disease.

Adult↗
PubMed1977

Amaurosis fugax and carotid artery disease: indications for angiography.

A prospective study of 80 patients presenting with amaurosis fugax was performed in an attempt to relate clinical features to angiographic findings in the internal carotid artery. Carotid bruit, transient cerebral ischaemic attacks, hypertension, and claudication were associated with a high prevalence of angiographic abnormality. Every patient who showed all these features had an operable lesion, as did 88% of those who had three features. In patients over 50 years of age carotid stenosis and atheromatous ulceration were occasionally found in the absence of bruit and transient cerebral ischaemia, but only one patient aged under 50 had an operable lesion and no associated features. Clinical features were therefore valuable in predicting the outcome of angiography, but it seems prudent to restrict angiography to patients aged over 50, who are most likely to benefit from surgery on the carotid artery.

Age Factors↗
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↗
PubMed1976

Growth and toxin production by Clostridium botulinum in moldy tomato juice.

Tomato juice inoculated with Cladosporium sp. or Penicillium sp. developed pH gradients with the upper portions near the mold mats having pH values near neutrality and the lower portions remaining more acid. Clostridium botulinum spores in these moldy tomato juices germinated, grew out, and produced toxin.

Beverages↗