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Biomedical subjects

R F White

Publications and source records attributed to R F White.

At least 91 records · Page 5Linked to original sources
PubMed1989

Failure of cholinergic agonist RS-86 to improve cognition and movement in PSP despite effects on sleep.

Postmortem studies of patients with progressive supranuclear palsy (PSP) have demonstrated loss of cholinergic neurons in the striatum, nucleus basalis of Meynert, and the pedunculopontine nucleus. These findings suggest that cholinergic drugs might be an effective treatment for this disease. We studied the efficacy of RS-86, a direct cholinergic agonist, upon motor abilities, eye movements, and psychometric performance in 10 patients with PSP during a 9-week placebo-controlled, double-blinded, crossover trial. Glycopyrrolate, a peripheral anticholinergic drug, was given throughout the trial to minimize cholinergic side effects. We used changes in rapid eye movement (REM) sleep to assess the degree of cholinergic activation achieved by treatment. Despite the enhancement of cholinergic activity in the CNS as indicated by increases in REM sleep latency and REM sleep time, RS-86 did not improve motor signs, eye movements, or cognition. Pharmacologic replacement of the cholinergic deficits in PSP does not result in significant clinical benefit.

Aged↗
PubMed1987

Influenza vaccination in community elderly. A controlled trial of postcard reminders.

Available strategies to increase influenza vaccination rates in the elderly have not been tested in the private sector where most elderly receive care. We performed a randomized controlled trial of a postcard reminder in the three private general internal medicine practices. The observed vaccination rates of 55% in experimental patients (N = 262) and 54% in control patients (N = 278) were similar, though much higher than estimated national rates of 20%. The data indicated that the baseline (control group) vaccination rate was high probably because study participants were exposed to many community vaccination cues, separate from the study cue. That vaccination rates were not higher after additional exposure to the study cue suggests that a "ceiling effect" occurred. Including 70 patients not randomized into the trial because they received flu shots prior to randomization, the vaccination rate in patients who had a clinic visit during autumn months was 75% compared to a rate of 52% in patients not visiting the clinic (P less than .001). Our results suggest that vaccination rates can be considerably higher in the private sector than those reported in the past, and that both vaccination cues and direct patient contact appear important to promote vaccination. This and other studies suggest that traditional cues may have a ceiling effect, yielding vaccination rates no higher than 55 to 65%; further increases in rates will require other approaches.

Aged↗
PubMed1986

The chemical induction of PR (b) proteins and resistance to TMV infection in tobacco.

Aspirin injected into Xanthi-nc tobacco leaves induces the production of PR protein and resistance to TMV. The concentration of PR protein and resistance increases with increasing aspirin concentration, up to a plateau. 2-Thiouracil and dioxohexahydrotriazine also induce PR protein when injected into tobacco leaves. Barium and manganese salts induced PR protein, but those of eight other cations did not. Certain salts were phytotoxic but did not induce PR protein, confirming that the production of PR protein is not a non-specific stress response.

Aspirin↗
PubMed1986

Effects of calcium channel entry blockers, nifedipine and nilvadipine, on colonic motor activity.

The effects of the dihydropyridine calcium channel entry blockers nifedipine and nilvadipine on colonic contractions were determined in vitro and in vivo. In circular muscle strips prepared from the canine proximal colon, cumulative concentration-response curves were generated to potassium chloride (KCl), acetylcholine (ACh) and substance P, and the effects of electrical field stimulation were determined. Responses to KCl and ACh were examined in circular muscle strips prepared from the monkey proximal and distal colon. Nifedipine (10(-8) - 10(-6) M) significantly decreased KCl-induced contractions, whereas equimolar concentrations of nilvadipine were less effective at modifying these responses. Both calcium channel entry blockers produced similar significant decreases in ACh, substance P and electrical field stimulation contractions. In anesthetized dogs, strain gauge force transducers were oriented to record proximal colonic circular muscle contractions. Colonic contractions to i.a. infusions of ACh, cholecystokinin-(26-33) and substance P were produced in a small segment of the proximal colon. Nifedipine and nilvadipine (200 micrograms/kg i.v.) significantly decreased maximal ACh contractions. Nilvadipine also decreased maximum cholecystokinin-(26-33) and substance P contractions. Both calcium channel entry blockers decreased systolic and diastolic blood pressure significantly at 100 micrograms/kg i.v. These results indicate that nifedipine and nilvadipine are equieffective at reducing colonic contractile activity to a variety of colonic stimulants and illustrate the importance of extracellular calcium in the mediation of colonic motility

Acetylcholine↗
PubMed1985

Long-term follow-up after single toxic exposure to trichloroethylene.

In an earlier report [Feldman and Lessell, 1967], neurologic findings following acute intoxication to trichloroethylene were presented. Facial anesthesia, asymmetric pupillary responses, and electrical evidence of sensorimotor neuropathy accompanied neuropsychological deficits, manifested by difficulty in solving sequential problems and poor memory affecting the acquisition of new information. Twelve years after the initial exposure, patches of hypalgesia over the malar eminences persisted and corneal reflexes remained absent, although sensation in the snout region was totally normal. Neuropsychological test results continued to demonstrate impaired attention and short-term memory as well as diminished visuospatial organization and sequencing, 16 years after exposure. In addition, MMPI profile and interview suggested continued depressive symptomatology. Eighteen years after exposure, findings included paresthesia and hypalgesia in the malar area of the face as well as myokymia of the facial muscles. Facial nerve latency studies were normal as were pattern shift visual evoked responses. The patient continued to have large pupils that reacted asymmetrically to light. In the right eye, contraction was synchronous in all segments of the sphincter. In the left eye, there was segmental contraction, suggestive of a tonic pupil. This report offers evidence of long-term residual oculomotor and ciliary reflex dysfunction as well as impaired neuropsychological performance as a result of acute TCE intoxication.

Affective Symptoms↗
PubMed1985

Late onset of Huntington's disease.

Twenty-five patients with late-onset Huntington's disease were studied; motor impairment appeared at age 50 years or later. The average age at onset of chorea was 57.5 years, with an average age at diagnosis of 63.1 years. Approximately 25% of persons affected by Huntington's disease exhibit late onset. A preponderance of maternal transmission was noted in late-onset Huntington's disease. The clinical features resembled those of mid-life onset Huntington's disease but progressed more slowly. Neuropathological evaluation of two cases reveal less severe neuronal atrophy than for mid-life onset disease.

Age Factors↗
PubMed1985

Occupational lead neurotoxicity: improvement in behavioural effects after reduction of exposure.

To evaluate critical exposure levels and the reversibility of lead neurotoxicity a group of lead exposed foundry workers and an unexposed reference population were followed up for three years. During this period, tests designed to monitor neurobehavioural function and lead dose were administered. Evaluations of 160 workers during the first year showed dose dependent decrements in mood, visual/motor performance, memory, and verbal concept formation. Subsequently, an improvement in the hygienic conditions at the plant resulted in striking reductions in blood lead concentrations over the following two years. Attendant improvement in indices of tension (20% reduction), anger (18%), depression (26%), fatigue (27%), and confusion (13%) was observed. Performance on neurobehavioural testing generally correlated best with integrated dose estimates derived from blood lead concentrations measured periodically over the study period; zinc protoporphyrin levels were less well correlated with function. This investigation confirms the importance of compliance with workplace standards designed to lower exposures to ensure that individual blood lead concentrations remain below 50 micrograms/dl.

Behavior↗
PubMed1983

Gold colitis.

A case of severe colitis, which developed in a patient with rheumatoid arthritis after administration of sodium aurothiomalate, is reported. Early recognition of this rare, but potentially fatal, complication is essential. Rectal biopsy should be performed as part of the early assessment.

Aged↗
PubMed1983

Leukapheresis: increasing the granulocyte yield with the Fenwal CS-3000.

By premedicating the donor with 60 mg prednisone in divided doses and processing more donor blood at higher flow rates than those specified by the manufacturer, one can obtain high yields of granulocytes and platelets (mean of 3.3 X 10(10) and 5.9 X 10(11), respectively) with the Fenwal CS-3000 blood cell separator. The steroid effect predominates over that of processing more blood. In the case of donors who are not stimulated by steroid, processing 10 L of donor blood at flow rates of 60 to 70 ml/minute results in a significantly improved yield of granulocytes (mean of 2.2 X 10(10) as opposed to 1.4 in the case of 7 L) and of platelets (6.1 X 10(11) versus 4.7). The concentrates contain about 50 to 60% less lymphocytes when donors are given steroid. With these modifications, the leukapheresis can still be accomplished in less than three hours and with minimal adverse effects on the donors.

Cell Separation↗
PubMed1983

The role of occupational lead exposure in the genesis of psychiatric and behavioral disturbances.

In a prospective study of lead neurotoxicity, exposed foundry workers and referents were evaluated using a comprehensive set of neurobehavioral tests. Other performance indexes were used including a questionnaire, physical examination, and nerve conduction testing. Results show increased rates of depression, confusion, anger, fatigue and tension among workers with blood levels over 40 mcg/dl. Other aspects of neurobehavioral function, including verbal concept formation, memory, and visual/motor performance were also impaired. In view of the large number of individuals exposed to lead in their work, specific inquiries should be made of individuals with affectual complaints to clarify the nature of their work and workplace exposure to lead.

Adolescent↗
PubMed1983

Monitoring neurotoxins in industry: development of a neurobehavioral test battery.

To facilitate the early detection of neurotoxicity in workers exposed to hazardous substances, we assembled a set of noninvasive neurobehavioral tests designed to assess memory, verbal concept formation, visuomotor performance, and mood. The tests were administered to an unexposed reference population and multivariate prediction equations were developed to control for effects of age, gender, and education. To define the briefest test set with appropriate sensitivity and specificity, we applied factor analysis and stepwise logistic regression to data from our referents and a group of lead-exposed workers. As a result, we have identified a comprehensive set of tests that can be administered in less than 40 minutes by trained medical technicians on plant premises and used to detect the early effects of neurotoxic substances on exposed workers. Guidelines for applying this technique to common work-place exposures, including other metals and organic solvents, are discussed.

Emotions↗
PubMed1981

Concomitant administration of granulocyte transfusions and amphotericin B in neutropenic patients: absence of significant pulmonary toxicity.

One hundred and ninety-five series of granulocyte transfusions in 144 patients were evaluated with respect to possible severe pulmonary toxicity from concomitant administration of granulocytes and amphotericin B. Dyspnea as a side effect of granulocyte transfusion was equally common among patients receiving amphotericin B and those in a matched control group not receiving amphotericin B. Granulocyte transfusions and amphotericin B were given simultaneously in 35 transfusion series, involving 32 patients. Respiratory deterioration, defined as the appearance of new pulmonary infiltrates on chest x-ray, occurred in 11 of these 35 episodes. Patients developing respiratory deterioration were similar to those not developing respiratory deterioration in age, diagnosis, disease status, duration of concomitant therapy, and outcome, but more often had positive fungal cultures as an indication for treatment (91% versus 58%; p = 0.1). In 8 patients, the episodes of respiratory deterioration were readily explained by congestive heart failure, by simultaneous bacteremia or fungemia, or by fungal pneumonia discovered at autopsy. One patient had a leukoagglutinin reaction (responsive to steroids) and the other 2 had unexplained, but reversible respiratory deterioration. We concluded that concomitant administration of granulocyte transfusions and amphotericin B is not associated with unexpected or rapidly fatal pulmonary toxicity and when appropriate, can be safely accomplished.

Adolescent↗