Search PubMed⌕ Search

Biomedical subjects

R J Marcus

Publications and source records attributed to R J Marcus.

35 records · Page 2Linked to original sources
PubMed1975

Effects of caudate nuclei removal in cats. Comparison with effects of frontal cortex ablation.

A method is described for performing one-stage ablation of the caudate nuclei through a midline approach in cats. Ten bilateral acaudate cats (BAc), with an average of 84% of caudate tissue removed, were studied for a average of over 6 months (three, for over 1 year). In addition, 11 cats with unilateral caudectomy (UAc), with an average of 95% of the nucleus removed, 10 cats with bilateral removal of the frontal-cortical areas (BFr), and four sham-operated cats (ShO) were also studied. Most cats were implanted with recording electrodes in neocortical area, the hippocampus, the potine reticular formation, neck muscles, and orbits. The results of the gross behavioral, neurological, and polygraphic observations are reported. 1. A long-lasting, behavioral change labeled "compulsory approaching syndrome" (CAs) was observed following surtery in all BAc cats. This syndrome was characterized by stereotyped, "compulsory," and prolonged approaching or following of persons, cats, or objects apparently aimed at a physical contact with the approached target and persisting under unusual conditions...

Animals↗
PubMed1975

The basal ganglia. A brief review and interpretation.

The data reviewed suggest that: 1. The BG are not only concerned with motor functions. 2. The BG are not directly involved in the control of neurophysiological, behavioral or homeostatic functions at a primary, elementary level. Thus, the effects of total ablation of the main component of the system, i,e. the caudate nuclei, demonstrates that the BG are not indispensable for life consciousness or the basic elementary integration of movements or sensory processes. 3. The BG operate at a high level of CNS integration and appears to be involved in two main types of, generally speaking, sensorimotor functions: a) The control of some of the organism-environment inter-relationships, both at a behavioral and neurological levels, a context of regulating the balance between approach and avoidance reactions. Some of the features of the acaudate cats suggest that this regulation might also include affective type reactions. b) The preparation or "setting up" of the organism for performance of both complex motor responses (response set), and of task requiring a high level of cognition (cognitive set). 26 High level of integration means here that, in the above functions, the BG control most probably operates upon performances not triggered reflexy, directly or indirectly, from the periphery but originated internally either "volitionally" or generated by symbolic, e.g. verbal, instructions. 4. The above functions appears to be accomplished by means of a modulatory action upon afferent signals arriving into the telencephalon and triggering efferent activities through forebrain output structures, particularly the neocortex. In normal conditions such modulation is seemingly carried on by means of a selective, flexible play of the intrinsic inhibitory mechanisms of the BG. When such control is disturbed either by pathology or by experimental manipulations, abnormal functional manifestations occur. These can be understood along the general concepts of (a) "release" from the BG inhibitory control ("compulsory approaching", hyperactivity, hyper reactivity, involuntary movements, abnormal postures, rigidity) or (b) "deficit" of the "setting up" for action postulated as a positive effect of striatal modulation (akinesia). The latter is viewed, therefore, as a permissive effect of the modulation, i.e., by selective removal of the inhibition, action is allowed to go through and to be expressed in actual performance. 5. Since lesions to individual BG structures, produced either neurosurgically in man or experimentally in animals, appear not to be capable of reproducing the complete clinical manifestations of any of the BG diseases, it follows that most of the BG syndromes in man must result from involvement of several BG components and often of other brain areas as well. More experimental work using the multiple lesions approach is needed to further ascertain this statement. 6. The literature on the effect of lesions and stimulation experiments, in particular, suggest that the BG are also involved in mental processes...

Acetylcholine↗
PubMed1970

Drug effect prediction by computer.

The mass of information available about effects of chemical substances (drugs) on behavioral, biochemical, and physiological systems of living organisms is so extensive as to defy traditional methods of analysis. A procedure that provides automated, computerized searches for patterns among these effects has been developed and has been applied to a data base constructed of medical and chemical information from The Merck Index. One promising result is the development of new hypotheses about mechanisms of drug action.

California↗
PubMedDate not supplied

AV fistula rates: changing the culture of vascular access.

PURPOSE: Data from the United States Renal Data System show about 30% of prevailing hemodialysis (HD) patients use arteriovenous fistulae (AVF), which falls far short of the Kidney Disease Outcomes Quality Initiative (K/DOQI) goals of 40-50%. Recent initiatives to increase the use of AVF in HD patients have been criticized as unachievable under realistic practice conditions. METHODS: A multidisciplinary effort to increase AVF use was undertaken at an outpatient HD center beginning in 1998. Strategies focused on education and recruitment of patients in both inpatient and outpatient settings, preservation of veins, pre-operative vein mapping, and education of staff. RESULTS: AVF rates increased from 32%, to 72% over 6 years. The percentage of prosthetic grafts decreased from 40% to 13%. Central venous catheters fell from 28% to 15%. Among residual patients with catheters, 77% had maturing fistulae, as well. Infection rates in the dialysis unit decreased by 39%. Bacteremia declined by 47%. These improvements have been sustainable over the past 12 months. CONCLUSIONS: Adherence to a strategic program similar to the Fistula First Initiative can increase fistula rates under ordinary practice conditions. High fistula rates can be achieved in male and female patients. Unanimous commitment among all members of the health care team is needed. Reduction in the risks of infection, bacteremia, endocarditis, and death may be derived from achievable changes in practice.

Journal Article↗
PubMedDate not supplied

Collateralization of the palmar arch by a failing radiocephalic fistula: an underappreciated complication of Cimino fistula anatomy.

Stenosis at the anastomosis of an arteriovenous dialysis fistula can cause fistula failure due to venous thrombosis. Three cases are presented in which anastomotic stenosis in radiocephalic fistulas resulted in radial artery occlusion with collateralization of ulnar artery flow across the palmar arch. Hand ischemia did not occur, and reductions in fistula efficiency were clinically subtle. Urea kinetics were compromised, and a characteristic palmar bruit was heard.

Adult↗
PubMedDate not supplied

Long-term outcomes of a fistula initiative: sustaining "fistula culture".

From 1998 to 2003, a low cost fistula initiative at Allegheny General Hospital increased the rate of AV fistulas from 32% to 72%. We present an additional 25 months of vascular access data, with stratification of results by gender and long-term patient survival data. These data show the self-sustaining nature of 'fistula culture' in an urban hemodialysis unit, and the survival benefits that result from increased fistula rates.

Arteriovenous Shunt, Surgical↗