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Biomedical subjects

D Brown

Publications and source records attributed to D Brown.

At least 1,045 records · Page 58Linked to original sources
PubMed1979

Effects of preparatory information about sensations, threat of pain, and attention on cold pressor distress.

Pain experience is conceptualized as a combination of stimulus sensations (e.g., aching) and emotional distress. In Experiment 1, less distress was reported to cold pressor stimulation by subjects first told about stimulus sensations than by subjects who were uninformed or were told about symptoms of bodily arousal (e.g., tension). Adding a pain warning to sensation information blocked distress reduction, presumably by eliciting an emotional interpretation of the stimulus. In Experiment 2, subjects attending only to hand sensations reported less distress than subjects attending to their bodies. This decrease in the power of the stimulus to provoke emotion is presumably mediated by a schema of hand sensations formed by attention. In Experiment 3, subjects attending to hand sensations early in the immersion and distracting themselves later reported the same low levels of distress as did subjects who attended to hand sensations throughout. Subjects distracted throughout and subjects attending to hand sensations later showed no distress reduction. Therefore, stimulus schematization must precede distress reduction. Implications for distress control are discussed.

Arousal↗
PubMed1979

Evaluation of posterior aortic wall echogram in diagnosis of mitral valve disease.

The clinical usefulness of detecting abnormal movement of the posterior wall of the aortic root by M-mode echocardiography was studied in 93 patients with common cardiac diseases (mitral and aortic valve disease, atrial septal defect, hypertrophic and congestive cardiomyopathy) and in 17 normal subjects. Though abnormally slow (less than 3 cm/s) or prolonged (greater than 240 ms) diastolic movement was confirmed to be common in mitral stenosis, since it occurred in 35 of 36 patients it was non-specific. Similar abnormalities frequently occurred in other patients with, for example, mitral regurgitation, aortic valve disease, after aortic valve replacement, and in both hypertrophic and congestive cardiomyopathy. The severity of mitral stenosis, assessed at operation, could not be accurately predicted from abnormalities of aortic root movement. Information derived from aortic movement was not diagnostic and did not predict severity in isolated mitral regurgitation though both the peak rate of systolic aortic motion and total aortic excursion were significantly greater than normal. We conclude that abnormalities of posterior aortic wall movement are frequent and their specificity and clinical usefulness are limited.

Adolescent↗
PubMed1979

An abnormality of cell behaviour in human dystrophic muscle cultures: a time-lapse study.

The initiation of monolayer mass cell cultures from adult human biopsies has revealed a striking abnormality in the growth and development pattern of muscle cultures from Duchenne-type dystrophy. This abnormality in cell behaviour was seen as early as 4 days in culture, well before myotube formation or confluence, and consisted of areas where cells clustered together in a multilayered mass rather than showing the typical monolayer distribution normally observed. To gain some insight into the mechanism of cell cluster development, we have examined such a culture by time-lapse cinematography and also the cell behaviour of other control cultures. The results of this study show that the clusters enlarged primarily by cell division and, to a lesser extent, by the acquisition of neighbouring cells. Furthermore, none of the single cells surrounding the clusters exhibited contact inhibition of movement. This behaviour was not observed in the other cultures examined. These findings could be indicative of an abnormality in the cell surface or cell-locomotory machinery of dystrophic cells.

Adolescent↗
PubMed1979

Atopy in inflammatory bowel disease.

Thirty-nine patients with ulcerative colitis and 35 with Crohn's disease have been investigated for evidence of reaginic hypersensitivity and compared with control subjects. There was no difference in the frequency of a personal or family history of atopy or in serum IgE levels. Similarly, no overall difference was noted in prick test responses to 21 allergens. However, further analysis of prick test responses showed that patients with inflammatory bowel disease responded more frequently to food allergens. This was highly significant when compared with healthy controls (p less than 0.001). The relevance of this finding to the aetiology of inflammatory bowel disease is discussed.

Adolescent↗
PubMed1979

The physiologic recovery trajectory as the organizing principle for the quantification of hormonometabolic adaptation to surgical stress and severe sepsis.

Preoperative and serial postoperative clinical, cardiovascular, physiologic, and metabolic studies were carried out on 86 patients undergoing coronary artery bypass surgery (CABG); and 48 patients undergoing abdominal general surgical procedures (GSEL). Multivariable statistical analysis of these data showed the patients to be in different physiologic states and to manifest several types of recovery trajectories that could not be discerned on clinical grounds alone. The CABG patients followed one of three types of cardiogenic recovery trajectories. In contrast, GSEL patients show a normal recovery trajectory different from all CABG types. When sepsis develops, and exaggerated stress response (A state) occurs, with increased oxygen consumption and a pattern of amino acids, fat, and glucose breakdown products, which is heightened but similar to the response of nonseptic GSEL patients. With progression of sepsis severity, an unbalanced hyperdynamic recovery trajectory (B state) develops in which a decrease in oxygen consumption is associated with increases in the aromatic amino acids tyrosine, tryptophane, and phenylalanine; and decreases in the branched-chain amino acids, leucine and isoleucine. Triglycerides rise as keto acids fall, but both lactate and pyruvate rise. Glucagon is persistently high, regardless of insulin levels. The quantifiably different physiologic recovery trajectories reflect altered hormone and metabolic states and imply different responses to therapy.

Abdomen↗
PubMed1978

A new in vivo method for quantitatively evaluating local anesthetics.

A method utilizing the reflex contraction of the retractor muscle of the hamster cheek pouch was developed to evaluate onset and duration of blockade produced by a local anesthetic agent infiltrated into or absorbed through the pouch epithelium. It provides a quantitative measure of reflex tension developed by the muscle as a function of afferent nerve conductivity in the pouch. The method is based upon the fact that when the pouch is everted activation of the retractor muscle results in the pouch being pulled toward the oral cavity. The method was validated by comparing the results with those obtained with other animal models and clinical trials. Ketocaine, an experimental drug, was evaluated for its efficacy as a local anesthetic when administered topically. In its present formulation the long latency of onset of blockade renders it impractical for clinical use.

Anesthetics, Local↗
PubMed1978

Comparison of firing patterns in oxytocin- and vasopressin-releasing neurones during progressive dehydration.

The electrical activity of neurosecretory cells in the supraoptic nucleus of the urethane-anaesthetized lactating rat was examined after periods of water deprivation ranging from 0-24 h. Supraoptic units were identified by antidromic activation following stimulation of the neurohypophysis, and classified as oxytocin or vasopressin cells according to their response during reflex milk ejection. In 65 vasopressin cells, dehydration increased the mean firing rate from 2.1 spikes/sec at 0 h to 6.8 spikes/sec at 24 h and caused a change from a slow irregular to a phasic firing pattern. Thus, after 6 h or more of dehydration, 84-100% of the vasopressin cells fired phasically, compared to 12% under normal conditions. In phasic vasopressin cells , the intraburst firing rates were closely related to the stages of dehydration, rising from a mean of 6.3 spikes/sec at 6 h to 12.0 spikes/sec at 24 h. However, no systematic relationship was observed between the stages of dehydration and the mean burst or silence durations. In 77 identified oxytocin units, dehydration increased the firing rate from 0.9 spikes/sec to 2.8 spikes/sec after 24 h, but only 3 (4%) of the cells showed phasic firing. Instead, the oxytocin units changed from a slow irregular to a fast continuous discharge. In conclusion, both vasopressin and oxytocin neurones are activated during chronic dehydration, but there is a marked difference in the pattern of their response. The phasic firing of the vasopressin cells may be important in increasing the occurrence of short interspike intervals and thus facilitating hormone release.

Action Potentials↗
PubMed1978

Fenestrae in the rough endoplasmic reticulum of Xenopus laevis hepatocytes.

The rough endoplasmic reticulum (RER) of Xenopus laevis hepatocytes was examined by freeze-fracture and by conventional thin section electron microscopy. Much of the RER was present as stacks of cisternae at the cell periphery but, in addition, large whorls of cisternae were seen in the cytoplasm in most sections. Freeze-fracture replicas revealed fenestrae in both stacked and whorled cisternae, although the fenestrae were more numerous in the whorls. The role of these fenestrae is unknown, but such structures would facilitate access of precursors to the protein synthetic machinery in this highly metabolically active cell type. This would be particularly important in RER whorls, where the innermost cisternae would otherwise be isolated from the rest of the cytoplasm.

Animals↗
PubMed1978

Rod-shaped particles in the plasma membrane of the mitochondria-rich cell of amphibian epidermis.

A freeze-fracture study has revealed rod-shaped intramembranous particles on the plasma membrane P-face (cytoplasmic leaflet) of the mitochondria-rich cell (or flask cell) of Xenopus laevis and Rana ridibunda epidermis. Such particles have previously been found in all other mitochondria rich cells examined by this technique, namely, the MR-cell of toad bladder epithelium, the dark cell of rat kidney collecting tubule, and the flask cell of Xenopus kidney collecting tubule. These particles are assumed, therefore, to be closely connected with the function of this cell type.

Animals↗
PubMed1978

Congenital deformities produced in hamsters by potato sprouts.

Dried gound potato sprout preparations from seven varieties produced congenital deformities in one strain of hamsters. Incidence of affected litters varied from 8 to 25%, depending on potato variety. Certain steroidal solanum and veratrum alkaloids produced similar defects. Neither peel nor tuber material was teratogenic from one of the potato varieties with highly teratogenic sprouts.

Abnormalities, Drug-Induced↗