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Biomedical subjects

R Brooks

Publications and source records attributed to R Brooks.

At least 127 records · Page 7Linked to original sources
PubMed1984

Cortical abnormalities in Alzheimer's disease.

Regional cerebral glucose metabolism, an index of neuronal activity, was compared in 20 patients with Alzheimer's disease and 8 age-matched normal volunteers by positron emission tomography following [18F]2-fluoro-2-deoxy-D-glucose administration. Overall cortical glucose utilization in the Alzheimer's group was 10 to 49% below that of control individuals. The posterior parietal cortex and contiguous portions of posterior temporal and anterior occipital lobes were most severely affected; frontal cortex was relatively spared. This pattern of cortical involvement is consistent with the major clinical features of Alzheimer's disease. Comparison of patients with early and more advanced dementia suggested that a substantial decline in glucose metabolism occurs before cognitive impairment becomes evident; once the patient is symptomatic, however, small additional metabolic decrements are associated with a marked deterioration in intellectual function.

Aged↗
PubMed1984

Characterization of cyclic nucleotide metabolism during human monocyte differentiation.

Cyclic nucleotide metabolism was studied during human monocyte differentiation. Intracellular cAMP increased 17-fold during in vitro differentiation. This increase was due to an increase in the specific activity of adenylate cyclase and a concomitant decrease in the specific activity of cyclic AMP phosphodiesterase. Monocyte adenylate cyclase activity was stimulated by guanine nucleotide, prostaglandin E1, isoproterenol, and epinephrine. Macrophage adenylate cyclase demonstrated less responsiveness to guanine nucleotide and was refractory to stimulation by prostaglandin E1, and to beta-adrenergic receptor agonists. In contrast to cAMP, total intracellular cGMP levels remained constant. Guanylate cyclase was found predominately in the cytosol of monocytes. The specific activity of soluble guanylate cyclase decreased during differentiation, while particulate activity increased more than 40-fold. Cyclic GMP phosphodiesterase activity remained stable during monocyte differentiation. The ratio of cAMP:cGMP increased dramatically from 2:1 in monocytes to 9:1 in macrophages suggesting that cAMP may be an important mediator of differentiation, while cGMP metabolism decreases in the fully differentiated nonproliferating macrophage.

Adenylyl Cyclases↗
PubMed1984

Detection of toxin production by Corynebacterium diphtheriae: results of a trial organised as part of the United Kingdom National External Microbiological Quality Assessment Scheme.

Four strains of Corynebacterium diphtheriae were sent to UK participants in the UK National External Microbiological Quality Assessment Scheme, who were asked to examine the strains for toxin production by in vitro methods. Laboratories achieved 162/176 (92%) and 160/175 (91%) correct results with two rapid toxin producers and 145/175 (82%) with a slow toxin producer. With a non-toxigenic strain 26/175 (15%) laboratories reported toxin production. Of the 173 laboratories reporting on all four strains, only 120 (69%) achieved the correct result for all. There was no significant association between the use of various methods and results, with the exception that laboratories using a full set of positive, weak positive, and negative controls made fewer errors than those not using controls. A number of unsatisfactory practices were revealed by the trial, however, and recommendations on preparation of inoculum, media, peptones, animal sera, and use of controls are made.

Bacteriological Techniques↗
PubMed1984

Phase I trial of esorubicin (4'deoxydoxorubicin).

A phase I study of 4'deoxydoxorubicin (esorubicin) was performed on an every-21-day bolus intravenous (IV) schedule in 36 patients with advanced cancer. Thirty-four patients were evaluable for toxicity analysis. Toxicity included mild nausea, occasional local skin reactions, and mild to moderate alopecia. Myelo-suppression was dose limiting. Clinically evident congestive heart failure was not observed. However, two patients developed premature ventricular contractions. Overall, esorubicin was better tolerated than doxorubicin at equally potent doses. Although response analysis was not the primary objective of this phase I study, minor responses were observed in melanoma, breast cancer, lymphoma, and gastric cancer. On the basis of this study, a starting dose of 30 mg/m2 IV every 21 days is recommended for good-risk patients with escalation to 32.5 mg/m2 depending on bone marrow tolerance. For patients with poor bone marrow reserve, a starting dose of 25 mg/m2 every 21 days is recommended. Phase II trials with esorubicin in this dosage schedule are clearly warranted in a wide variety of metastatic neoplasms including a substantial population of patients who have not received prior chemotherapy.

Adult↗
PubMed1983

EEG, transmission computed tomography, and positron emission tomography with fluorodeoxyglucose 18F. Their use in adults with gliomas.

We evaluated the relationship between findings from EEG, transmission computed tomography (CT), and positron emission tomography in 23 adults with gliomas. The cortical metabolic rate was suppressed in patients with and without focal slowing. Focal delta activity was not related to involvement of gray or white matter. Rhythmic delta activity and focal attenuation of background amplitude on EEG, however, were correlated with involvement of the thalamus.

Adult↗
PubMed1983

[18F]fluorodeoxyglucose positron emission tomography in refractory complex partial seizures.

Positron emission tomography with simultaneous electroencephalographic monitoring was performed with [18F]fluorodeoxyglucose in 20 patients with complex partial seizures who had normal computed tomographic scans. Seven patients had only unilateral epileptiform discharges on the electroencephalogram, 3 had predominantly unilateral discharges, and 10 had nonlocalized epileptiform abnormalities. Positron emission tomography showed a hypometabolic lesion in 16 of the 20 patients. Pathological changes in the hypometabolic region were found in postoperative specimens in 4 of 5 patients studied. Positron emission tomography was unaffected by the seizure frequency, state of alertness, or number of spike discharges during the scan. There was a tendency for patients to have higher overall metabolic rates when taking less medication. Seizures occurring during [18F]fluorodeoxyglucose uptake in 3 patients produced a hypermetabolic area at the interictal hypometabolic focus. Positron emission tomography sometimes showed more widespread hypometabolism than suspected on the basis of the scalp-recorded electroencephalogram. The frontal lobe showed a greater degree of hypometabolism than the temporal lobe in 3 patients. Focal lesions may be identified by positron emission tomography even if the electroencephalographic abnormality is not well localized.

Adult↗
PubMed1983

Criteria for evaluating a computer aid to clinical reasoning.

The acceptance or rejection of computer aids to clinical reasoning is determined not only by the preferences and prejudices of potential users, but also by whether the output generated by the computer aid represents sound clinical judgment. This paper deals with the issue of the appropriate criteria for evaluating the clinical 'reasoning' of computer aids. Evaluation of a computer aid should include an assessment of the accuracy or appropriateness of its conclusions and an assessment of the scope of its considerations. In order to use a conclusion generated by a computer aid as a basis for clinical action, information must be available on the alternative conclusions that might have been drawn, the degree of confidence in each conclusion, and the consequences that may result from acting upon the wrong conclusion. If this information is not generated as part of the output of a computer aid, it may be obtained through the use of its explanation and display capabilities, if the aid has such capabilities. Explanation and display capabilities permit the examination of the operations of the computer aid. Examination of a computer's operations is also the most feasible means to evaluate the soundness of its 'reasoning'.

Diagnosis, Computer-Assisted↗
PubMed1982

Activity of isotretinoin against squamous cell cancers and preneoplastic lesions.

We investigated the effect of the synthetic vitamin A derivative isotretinoin (13-cis-retinoic acid) on advanced cancers in 103 patients and on preneoplastic lesions in five patients. Six of 14 patients with squamous cell epithelial cancers had objective regressions of skin or subcutaneous metastases. Three of five patients with preneoplastic lesions had objective responses. The major dose-limiting toxic effects were reversible dermatitis, emotional lability, and headaches. We conclude that the growth of some squamous cell epithelial malignancies can be inhibited by isotretinoin and suggest that other retinoids should be evaluated as antitumor agents.

Antineoplastic Agents↗
PubMed1979

A language-cultural course for foreign psychiatric residents.

Foreign medical graduates are an important component of the health care system in the United States. All foreign medical graduates have acculturation problems, but they are especially aggravating among foreign psychiatric residents. These difficulties affect the personal lives of the foreign residents as well as crucial teacher-student and doctor-patient relationships. The authors report on an effort to further define these problems in a residency program and their systematic attempts to solve them by offering a special course. The program they describe benefitted not only the foreign residents but their families and the residency program itself.

Acculturation↗
PubMed1978

Verbal conditioning of male and female schizophrenics as a function of experimenter proximity.

Verbal conditioning of male and female schizophrenics and nonschizophrenics was observed as Ss sat at different distances and orientations from an E who delivered a positive word/positive tone reinforcer ("Good"). Results indicated that the presence vs. absence of diagnostic differences in learning depended on (a) the sex of the Ss; and (b) the distance that Ss sat from the E. The absence of overall diagnostic group differences in learning and the finding that in some proxemic conditions schizophrenics learned more than nonschizophrenics are consistent with the view that under appropriate conditions schizophrenics emit behaviors that are incompatible with an assumption of schizophrenic deficit.

Conditioning, Classical↗
PubMed1977

General practitioners in the Western Metropolitan Health Region of Sydney.

A comprehensive survey of the number of general practitioners in the Western Metropolitan Health Region of Sydney identified 753 general practitioners with one or more practice locations in the region; this was the equivalent of 711 full-time general practitioners, and represented a general practitioner-population ratio of 1:1533.

Australia↗