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Biomedical subjects

R Cooper

Publications and source records attributed to R Cooper.

At least 379 records · Page 21Linked to original sources
PubMed1978

Expornitic of avian pox in a zoo.

During a 6-week period at the San Diego Zoo, avian pox occurred in 9 pheasants representing 5 species. Lesions were limited to facial skin and consisted of epithelial cell hyperplasia, secondary inflammatory changes, and intracytoplasmic eosinophilic inclusion bodies which, by electron microscopy, were shown to contain pox virus. The disease was self-limiting in 7 pheasants, but 2 pheasants died. Free-ranging Indian red junglefowl were implicated as the source of the infection.

Animals↗
PubMed1978

Chronic ventricular ectopic activity and sudden death.

The majority of deaths from coronary heart disease (CHD) occur before the victims receive medical attention. Chronic ventricular ectopic activity (VEA) is a well-established predictor of coronary mortality as well as sudden death. Evidence that chronic VEA is independently and causally related to sudden death, however, remains equivocal. Only more advanced grades of chronic VEA appear to be significant. Arrhythmias are clearly more common in patients with advanced coronary obstruction, and therefore prone to new ischemic events and their associated electrical disturbances. Autopsy studies are limited in their ability to identify an acute myocardial infarction in patients who die suddenly, but experience with the mobile coronary care units has reemphasized the role of acute ischemia. The prospective, randomized trial, including reliable assessment of VEA, offers the only definitive means of identifying the contribution of chronic VEA to the incidence of sudden death from CHD.

Arrhythmias, Cardiac↗
PubMed1977

Respiratory infection in an intensive care unit.

A postmortem bacteriological study of Black children in a respiratory intensive care unit showed that Pseudomonas aeruginosa was the most common opportunistic pathogen and that it usually complicated a viral infection. In a parallel study of non-debilitated patients in general hospital wards Klebsiella aerogenes and Escherichia coli were the most frequently isolated organisms. Counter-immuno-electrophoresis was used for the identification of Pseudomonas-precipitating antibody in serum and tracheal secretions, and also of Pseudomonas antigen in the latter.

Antigens, Bacterial↗
PubMed1977

Cortical potentials associated with the detection of visual events.

A positive-going potential, which reaches a maximum at the vertex and midline parietal scalp electrodes, occurs in the human being when an infrequent, significant event occurs in a continuously observed visual display. It is not time locked to eye movements or operant response and appears to be generated when the observer recognizes an event that he has been instructed to detect.

Cerebral Cortex↗
PubMed1977

Post-streptococcal glomerulonephritis in African children.

Streptococcal infection remains almost the sole cause of the clinical syndrome of acute glomerulonephritis in African children. Evidence for this is in elevated levels of antistreptolysin "O" (ASO) titre in 93% of 28 patients and growth of Group Abeta haemolytic streptococci from the skin and throat in 32%. Spread of infection from the skin, where lesions were present in all patients, to the throat would account for positive cultures at both sites and the frequent and vigorous antistreptolysin "O" responses. Clinical recovery occurred in most within seven days and in all within 60 days of admission. IgG and IgA, but not IgM, were increased in patients; C4 was normal in the majority and low in seven out of 24 (29%), C3 was diminished in 26 out of 28 (93%) and the mean level of C3 PA was lower than in controls. Total haemolytic complement paralleled C3 values; C3 breakdown products were not detected in any patient. Renal biopsies in seven out of 28 patients showed typical histological changes of diffuse exudative proliferative glomerulonephritis on light microscopy and fibrinogen and C3 on immunofluorescent staining. These findings suggest that events leading to glomerular damage in acute post-streptococcal nephritis in African children involve activation of both classical and alternative pathways of complement proteins and also confirm the well recognized and predictable nature of the disease, irrespective of geographical distribution.

Acute Disease↗
PubMed1977

A new and superior adrenal imaging agent, 131I-6beta-iodomethyl-19-nor-cholesterol (NP-59): evaluation in humans.

We have reported tissue distribution studies in rats and dogs with a new adrenal imaging agent. 131I-6beta-iodomethyl-19-nor-cholesterol (NP-59). This agent concentrated five times higher in the adrenal cortex than 131I-19-iodocholesterol without increased concentration in non-adrenal tissues. We now report in 34 patients, the findings on scintigraphy with NP-59 compared with angiograms and/or adrenal vein hormone levels and histopathology, including 13 patients with hypercortisolism, 12 with primary aldosteronism, 2 with low renin hypertension, 5 with catecholamine excess, 1 with a liver metastasis from an aldosterone producing adrenal cortical carcinoma, and 1 with anaplastic adrenal cortical carcinoma. NP-59 adrenal cortical uptake was more rapid and intense and background activity was less prominent, allowing earlier and more definite interpretation of images than was possible with 131I-19-iodocholesterol.

Adrenal Cortex Neoplasms↗
PubMed1976

Causes of initial visual loss following blunt ocular injuries: an experimental study.

We have investigated in anaesthetised pigs the electrical responses of the retina to light after blunt injuries to the eye. Retinograms, cortical visual evoked responses and intraocular pressures were recorded before and after non-perforating mechanical trauma of sufficient severity to produce traumatic retinal opacification. After injury, applanation pressures rose up to 34 mm. Hg above normal, reaching peak values 4 to 12 minutes after trauma and returning to pre-trauma levels after about 45 minutes. These pressure changes were not responsible for the immediate abolition of the B wave of the retinogram or of the cortical visual evoked responses which occurred after trauma, but increases of intraocular pressure modified the recovery pattern of the visual evoked response.

Animals↗
PubMed1975

Frequency dependence of the transmission of the EEG from cortex to scalp.

Simultaneous recordings of the EEG at subdural and scalp electrodes often show very different activities. Large amplitude activity with maximum power between 15 and 30 c/sec can be often observed on the subdural electrodes together with smaller amplitude lower frequencies, whereas on the scalp only a small part of this high frequency activity is seen and the lower frequencies dominate. The impedance between cortex and scalp has been shown to be similar for low and high EEG frequencies and the high attenuation of the beta activity at scalp electrodes is believed to be due to summation of polyphasic cortical activity. The weighted summation of this polyphasic activity across a limited cortical area (spatial average) is similar to the activity of a non-recursive filter between cortex and scalp and has a low pass characteristic.

Brain↗
PubMed1975

Selective averaging of the intracerebral click evoked responses in man: an improved method of measuring latencies and amplitudes.

Individual click evoked responses recorded in the right and left frontal lobe in man have been correlated with different templates, that is, particular wave shapes of evoked responses, and from the maxima of the cross correlation functions individual estimates were obtained of amplitude and latency. Averages were then made of evoked responses having particular amplitude and/or latency values. Using such selected trials for averaging, better results were obtained and artificial amplitude damping avoided. It was found for example that the component N90 varied in latency between 75 and 100 msec and was linked with the behaviour of the contralateral recorded potential amplitude of P150. Furthermore it was found that the biphasic potential N230 P430 was very unstable in latency and the amplitude of the averaged potential using all trials was about 30% too small.

Acoustic Stimulation↗
PubMed1975

Intention tremor--a method of measurement.

A method of measuring and analysing intention tremor using a linear accelerometer is described. Reasons are given for measuring this particular parameter of the tremor, for using this specific energy conversion device, and for employing the particular form of analysis. A comparison of the numerical values obtained for the amount of tremor activity, compared with a corresponding clinical grading, is made for 30 patients with intention tremor due to a variety of pathological causes. It is shown that the method gives clear correlation with the clinical assessments, although certain discrepancies are noted, and their importance discussed.

Acceleration↗