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Biomedical subjects

C Don

Publications and source records attributed to C Don.

15 recordsLinked to original sources
PubMed1999

Differential expression of c-fos mRNA within neurocircuits of male hamsters exposed to acute or chronic defeat.

Chronic exposure to stress has been implicated in physical and mental illness, and such experiences can produce alterations in the connectivity and number of neurones within the brain to variations in the expression of specific genes. The purpose of this study was to determine how repeated exposure to social defeat affects neuronal activation patterns within the male Syrian hamster brain. Toward this end, the levels c-fos mRNA were compared among three groups: (1) handled controls (HC); (2) acutely defeated males (AD); and (3) chronically defeated males (15 min aggression daily, 7 days) exposed to an acute challenge (CD). Plasma glucocorticoids were also measured and compared among groups as an index of neuroendocrine activity. The results show a selective pattern of habituation of immediate early gene expression within the brains of chronically defeated males. In particular, c-fos mRNA levels were significantly decreased within the paraventricular nucleus of the hypothalamus (PVN), supraoptic nucleus of the hypothalamus, septohypothalamic nucleus, intermediate subdivision of the lateral septum, central amygdaloid nucleus, and the amygdalohippocampal area in the CD group exposed to an acute challenge when compared to males defeated only once. In contrast, c-fos expression within the anterior and ventromedial nuclei of the hypothalamus, dorsal periaqueductal grey, dorsal raphe, cuneiform nucleus, and locus coeruleus did not differ between AD and CD groups. Similarly, plasma levels of cortisol and corticosterone in CD group were equivalent to those observed after a single defeat experience. We discuss the possibility that decreased expression of c-fos mRNA within the PVN and other brain regions of defeated animals-in the presence of elevated adrenal steroids-may reflect a state of molecular plasticity that could alter neurotransmission within the limbic-hypothalamo-pituitary-adrenocortical axis. In contrast, brain areas that maintain relatively high levels of c-fos mRNA following repeated defeat may reflect processes less likely to adapt such as defensive behaviour.

Aggression↗
PubMed1997

In vivo measurement method of ovarian dose during barium enema examinations.

Barium enema is currently the most commonly performed fluoroscopic procedure. In general, it is not possible to measure directly gonadal dose in women during this procedure. A measurement method to allow an estimate of radiation dose to the ovaries is described. The method uses thermoluminescent dosimeters attached to the tip of the rectal tube to measure radiation dose during procedures. A series of measurements was made at a university hospital equipped with an image-intensified, camera-based X-ray system and at a private clinic with a mirror-optics X-ray system. Measurements were made on both single contrast and double contrast barium enema examinations. On the image-intensified, camera-based X-ray system, the average results of dose measurements for single and double contrast barium enema were 3.11 mGy and 6.50 mGy and the results for the mirror optics system were 1.57 mGy and 3.64 mGy, respectively.

Barium Sulfate↗
PubMed1990

Body fluid volume status in hemodialysis patients: the value of the chest radiograph.

Thirty-six pairs of chest radiographs in stable patients undergoing long-term hemodialysis were taken immediately before and after dialysis. They were evaluated in pairs, without indication as to before or after, for radiologic signs of fluid retention, and to identify if changes in these signs could be correlated with body weight and removal of body fluid by dialysis. The radiologic signs assessed were those of increased blood volume (degree of pulmonary vascularity, vascular pedicle width (VPW), transverse cardiac diameter (TD), and azygos vein width (AVW), of interstitial pulmonary edema (perihilar haze, Kerley B lines, bronchial wall thickening and thickening of the minor fissure) and pleural effusion. At least one sign of interstitial pulmonary edema was present in 28 (78%) of the pre-dialysis chest radiographs, and resolved with dialysis in all but three (8%). Pleural effusions were present in 10 (28%), of which 5 (14%) persisted after dialysis and 5 resolved. Pulmonary vascularity was found difficult to assess quantitatively, and AVW was not found to be a useful indicator of volume status. Vascular pedicle width decreased significantly with dialysis and was a useful indicator of volume status. The most reliable indicator, however, was the transverse diameter of the heart, the simplest of the measurements used. Both TD and VPW may be useful in estimating dry weight when clinical assessment is difficult.

Azygos Vein↗
PubMed1989

Peripheral upper lobe collapse in adults.

Atypical (peripheral) upper lobe collapse, simulating loculated apical pleural effusion or other localized pleural disease, occurs when the collapsed lobe maintains its adherence to the lateral chest wall. Fifteen such cases are known to have been reported, 12 in children (ten of them infants) and three in adults. Two additional cases, occurring in adults with carcinoma of the bronchus, are presented here. In one case, adherence of the visceral to the parietal pleura was shown to be due to malignant infiltration. In both cases, the margination of the collapsed lobe, which on images resembles apical pleural disease, was attributed to hyperexpansion of the superior segment of the lower lobe.

Carcinoma, Squamous Cell↗
PubMed1988

The 1987 Gordon Richards memorial lecture: the future of radiography--cassetteless or filmless?

A six-year experience of the first cassetteless radiology department has shown that it produces considerable improvement in speed and efficiency of patient handling, reduced physical labor for the technician, and substantial financial savings, amounting to approximately one third of the total non-medical budget. This is contrasted with the potential cost of a totally digital (filmless) department. The digital acquisition devices and their image processing systems are considerably more expensive. Image display comparable to conventional radiographys (for example the full-sized chest film) is markedly inferior in resolution and totally prohibitive in cost. Image storage and recall of the same amount of data as currently handled by the conventional department are presently beyond the capabilities of any commercial communications system, and the potential cost is completely unacceptable. Projections of the imminent advent of the filmless department are grossly over-optimistic, whereas the development of cassetteless systems offers an alternative route to improved patient handling and increased cost-efficiency.

Costs and Cost Analysis↗
PubMed1988

Postmediastinoscopy changes in the chest radiograph.

A series of 50 postmediastinoscopy erect portable films was reviewed and compared with 100 normal control films to determine how often changes might develop after mediastinoscopy that could simulate mediastinal adenopathy. Such findings were found in 54% of postmediastinoscopy patients; they consisted of a thickened right paratracheal stripe (RPS) in 30%, a right paratracheal mass in 22%, and a left superior mediastinal mass in 4%. These changes usually resolve in a few days, but they may cause an initial erroneous impression of mediastinal adenopathy if recent previous films are not available for comparison. An indistinct RPS without a right paratracheal mass was found in 47% of control erect portable radiographs and was not considered a relevant finding.

Humans↗
PubMed1987

Experience with the first cassetteless radiology department.

A 6-year experience with the first cassetteless radiology department has shown that it (1) considerably speeds the examination of the patient and allows the technician to stay with the patient throughout the entire course of the examination; (2) relieves the technician of the burden of manually transporting lead-backed cassettes to and from the darkroom; (3) gives the radiologist closer control over gastrointestinal examinations and allows him to see the processed films during the course of the examination; (4) greatly reduces the number of radiology technicians required; and (5) eliminates a great deal of the function of the darkroom technicians. The cost-efficiency and productivity of the department have been compared with other teaching hospitals in Ontario, the basis for the comparison being the Canadian workload system, which compares units of work. Nonmedical productivity and cost-efficiency are shown to be improved by a factor of 30-60%, with financial savings amounting to about 25% of the total budget.

Automation↗
PubMed1987

Tracheal parallax in the assessment of mediastinal shift.

Tracheal shift is a basic radiological sign in interpreting chest films, and there is an impression that it cannot be assessed when the patient is rotated. From a consideration of parallax, it is shown that although the trachea and medial ends of the clavicle both shift in the direction of the rotation, the trachea, lying behind the medial ends of the clavicle, shifts in an opposite direction in relation to the clavicles. This is confirmed by postero-anterior films of a normal patient. If, therefore, the trachea shifts in relation to the clavicles in the same direction as the patient is rotated, genuine tracheal shift is present. An example illustrates the importance of being able to detect tracheal shift despite rotation, in a patient with proven traumatic rupture of the aortic arch.

Adult↗
PubMed1985

The vascular converging points of the right pulmonary hilus and their diagnostic significance.

The shadows of the right descending pulmonary artery, the superior pulmonary vein crossing it, the middle lobe artery, and branches of the artery supplying the superior segment of the lower lobe converge distinctly at the right hilus. Because the right pulmonary artery bifurcates within the mediastinum, the arteries of the right upper lobe form a second though less obvious converging point above this level. In contrast, the left pulmonary artery does not bifurcate until it reaches the left hilus, providing only a single converging point on that side. A survey of 100 chest radiographs showed that the two converging points on the right could be distinguished in 95 cases, with the upper one being situated somewhat above the single point on the left in 83. In the absence of lobar resection, finding only one converging point on the right is suggestive of collapse of either the upper or lower lobe, whereas visualization of both points excludes major atelectasis.

Humans↗
PubMed1977

The nature and significance of peribronchial cuffing in pulmonary edema.

So-called "peribronchial cuffing" in acute pulmonary edema appears to be caused by edema involving the bronchila wall as well as the peribronchial interstitial space, and this was confirmed at autopsy in a patient with acute left heart failure. Edema of the bronchial wall indicates transdation from capillaries derived from the bronchial rather than the pulmonary atery, which may well explain all of the radiological manifestations of acute interstitial edema. The possible role of this circulation in the production of acute alveolar edema is also discussed. The significance of the bronchial artery circulation in the production of acute pulmonary edema warrants reevaluation.

Bronchi↗