Biomedical subjects
J A Clarke
Publications and source records attributed to J A Clarke.
A case for revising the 'weight gain during pregnancy' guidelines for Australian women.
In 1989, an average weight gain during pregnancy of 14 kg was determined for a sample of 1,253 public patients at the Royal Women's Hospital, Brisbane. This greatly exceeded the weight gain of 10 to 12 kg which was recommended by the hospital and which is based on United States of America (US) data. The finding prompted a comparison of characteristics of Brisbane mothers (weight gain during pregnancy, age, prepregnant weight, height, birth-weight of infant, etc) with the characteristics of mothers in two large US studies. Significant differences were found to exist with Brisbane women being taller, heavier in body mass, more overweight and gaining less weight during pregnancy than the US women. Unexpectedly, the birth-weight of infants was neither more nor less than reported for the American studies. Further studies to gain more information about Australian women during their pregnancies should be undertaken.
Medial fasciocutaneous flap of thigh for release of post-burn groin contractures.
Post-burn groin contractures, though uncommon, cause some patients distressing symptoms which are difficult to treat. Recurrence of contracture and symptoms is common and multiple operations are often required to control symptoms. We describe the use of the medial thigh fasciocutaneous flap for release of these contractures. Six flaps have been raised in four patients and symptomatic relief has been excellent in three. There have been no contracture recurrences.
Malignant melanoma in Scotland: trends in incidence and survival, 1968-87. A review prepared by the CSA Information and Statistics Division for the Health Monitoring Group.
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Quantitative studies of the vasculature of the carotid body in fetal and newborn sheep.
Resetting of the hypoxic sensitivity of the carotid chemoreceptors from the fetal to the adult arterial PO2 range follows the rise in PO2 which occurs after birth. The mechanism of this resetting is unknown. To study whether it is accompanied by a change in the carotid body microvasculature, 2 pairs of carotid bodies from fetal sheep (145 days gestation) and 2 pairs from 7-8 days-old lambs were examined. The ratio of the area of small vessels (6-16 microns diameter) or of larger vessels (greater than 16 microns diameter) to the total area of individual lobules of the carotid body was measured, using a semi-automatic image analysis system. This quantified the number and total cross-sectional area of small vessels and of larger vessels in 20 sections of 5 microns thickness taken at random from 200-350 sections cut from each carotid body. When the carotid bodies of the fetus and neonate were compared, the neonates showed increases in the percentage of the lobule area occupied by both small and large vessels, but the difference was only significant in the case of the larger vessels. There was no difference in the ratio of the area occupied by smaller vessels to the extravascular area of the lobule. Our results do not support the idea that the post-natal resetting of chemoreceptor sensitivity from the fetal to the post-natal range is accompanied by a change in the perfusion of the carotid body chemoreceptor cells.
The application of clinical guidelines for skull radiography in the Accident and Emergency department: theory and practice.
Clinical guidelines for the selection of patients with head injuries for skull radiography, based on those formulated by the Royal College of Radiologists, were introduced into the Accident and Emergency department at the Manchester Royal Infirmary. Before the guidelines were implemented 94 skull X-rays were obtained per 1000 new casualty attenders. After implementation the rate of skull radiography initially fell by 40%, but thereafter slowly increased so that 12 months later it had returned to the pre-implementation level. During the first and second 6 months of the study reductions of 37% and 17%, respectively, were achieved. Although the overall annual reduction was only 27% an estimated saving of almost 10,000 pounds was made. Although clinical guidelines for skull radiography can reduce the number of skull radiographs without detriment to the care of the head-injured patient, their constant use is difficult to sustain. The application of clinical guidelines needs regular monitoring. Referring clinicians and radiologists need to be strongly motivated if such guidelines are to find a useful place in clinical management.
Tuberculous dactylitis in childhood. The need for continued vigilance.
A case of tuberculous dactylitis in a 3-year-old Chinese boy is presented and the radiographic findings and differential diagnosis discussed. Although this is a rare condition, the diagnosis should be considered when a member of the immigrant community presents with an unusual bony lesion.
Comparison of the size of the vascular compartment of the carotid body of the fetal, neonatal and adult cat.
The carotid bodies from full-term fetal cats, 3- to 4-day-old neonates and adult cats were perfusion-fixed at normal arterial blood pressure with 3% phosphate-buffered glutaraldehyde. Serial 5-microns sections were cut and stained by the MSB method. Using an interactive image analysis system, determinations were made of the volumes of the carotid body and of its vascular and extravascular compartments. Compared to the fetus, the carotid body of the neonate increased in volume by 51% and by 286% in the adult cat. There was a proportional increase in the volumes of the vascular compartment and of the small vessels (5-12 microns diameter) in that compartment. The volume of the small vessels, expressed as a ratio of the total volume of the organ, remained constant in the three animal groups at 5-7%. The small vessel endothelial surface area, expressed as a ratio of the extravascular volume (which was assumed to consist largely of type 1 and type 2 cells), was the same in the neonate as in the full-term fetus. Thus, there were no apparent quantifiable morphological features of the carotid body and its vasculature which would account for the resetting of the hypoxic sensitivity of the organ from the fetal to the adult range within a few days of birth.
The carotid body of the mini-pig.
The bilateral distribution of carotid body type 1 and 11 cells was investigated in 3 mini-pigs by serially sectioning the carotid bifurcation regions. The majority of type 1 and 11 cells occurred bilaterally in close proximity to the wall of the occipital artery or one of its small proximal branches, the internal carotid artery and the common arterial trunk. A division of connective tissue surrounded the type 1 and 11 cells with defineable but very irregular borders and this combination of connective tissue and cells constituted the principal mass of the carotid body. In the majority of specimens the cells were diffusely arranged giving a fragmented appearance to the organ but in 2 specimens part of the carotid body was discrete, adopting an ovoid or crescent-shaped appearance over a limited rostral-caudal part of its extent. Arteries to the carotid body originated from the occipital arterial tree in the vicinity of the division of the common arterial trunk and less commonly from the common arterial trunk itself. A supplementary blood supply came from unidentified connective tissue arterioles. In 2 out of 6 specimens type 1 and 11 cells were associated with cervical nerve trunks. Periadvential type 1 and 11 cells were observed in one out of 6 specimens lying dorsal to the common arterial trunk. From our data on 6 specimens, three dimensional reconstructions were made of ventral views of the distribution of carotid body type 1 and 11 cells. On account of the diffuse arrangement of the mini-pig carotid body, morphometric analysis of the organ volume was not feasible.
Intradermal inoculation with Heptavax-B. Immune response and histologic evaluation of injection sites.
The high cost of hepatitis B vaccine has limited its widespread use. Low-dose, intradermal injections of vaccine represent one option for reducing the cost. In this study, 92 nonimmune medical students were given three 0.1-mL intradermal injections of Heptavax-B containing 2 micrograms of hepatitis B surface antigen (HBsAg) at 0, 1, and 6 months. By 6 months, 90% of the subjects had developed protective levels of antibody to HBsAg (greater than or equal to 10 mIU/mL). Follow-up at 1 year showed a geometric mean concentration of antibodies to HBsAg of 396 mIU/mL for the group, and 95% had levels of antibody to HBsAg greater than or equal to 10 mIU/mL. A level of antibody to HBsAg of greater than 100 mIU/mL also was observed in more than 75% of subjects. Side effects included induration of the inoculation site in 18% at 6 months, which disappeared by 12 months, and macules that persisted at 1 year in 63%. The administration of hepatitis B vaccine intradermally is an attractive, low-cost alternative in the United States, where universal vaccination of preschool children or adolescents is being contemplated, and where booster doses are being considered.
Survival of cultured allografts in patients with burns assessed with probe specific for Y chromosome.
The aim of the study was to determine the fate of cultured skin allografts in patients with burns. In situ DNA hybridisation with a Y probe (pHY 2.1) was used to detect cells carrying the Y chromosome (the probe being visualised by the alkaline phosphatase-antialkaline phosphatase method) in biopsy specimens taken from cultured allografts derived from donors of the opposite sex to the recipients (20 patients with burns). Specimens were taken within a week, between one and three weeks, between four and six weeks, and more than six weeks after grafting. Only two of the 27 biopsy specimens contained cells that were the same sex as the donor; both were taken within a week after grafting. In the 25 other specimens the epithelial cells were the same sex as the recipient. Cultured skin allografts showed no evidence of survival in patients with burns, which suggests that they are probably not suitable for long term management of burns but may be useful as short term biological dressings.
Skeletal injury in thermal trauma: a review of management.
This paper reports the results of treating 12 patients, from a total of 1011 admissions to the burns unit, who had a combination of extensive burns, fractures and exposed bone or joint. Our results suggest that the benefits of early skeletal stabilization outweigh the increased risks of infection in the burned patient, and that areas of exposed bone or joint less than 3 cm across the smallest axis may be successfully treated by repeated split-skin grafting, but larger areas require early excision and flap coverage for optimum rehabilitation.
Techniques for measuring the static and dynamic properties of the patella.
An electrogoniometric method was used together with a new standardized radiographic technique to accurately determine the rotation of the patella during knee flexion of both normal subjects and patients referred for retropatellar pain. A preliminary study using these techniques shows that retropatellar pain is very much a multi-factoral clinical problem and that combinations of patello-femoral articulation abnormalities, patellar shape and mechanical influences are present in all forms of the painful patella.
Use of the lithotripter in the burned patient as an aid to mobilization.
A young lady with extensive burns and multiple fractures developed renal calculi, and repeated attacks of colic, accompanied by nausea and vomiting which delayed her hyperalimentation and mobilization. The insertion of J stents stopped these episodes of colic and the stones were eliminated by extracorporeal lithotripsy before the burn wounds were healed. Urinary infections cleared and rehabilitation thereafter was uncomplicated.
Carotid chemoreceptor function and structure in the atherosclerotic rabbit: respiratory and cardiovascular responses to hyperoxia, hypoxia and hypercapnia.
We tested the following hypothesis: if carotid body blood flow, and hence the relationship of the frequency of discharge in chemoreceptor afferent fibres to arterial PO2, were affected by atherosclerotic change, then a modification of the control of the respiratory and cardiovascular systems might result. Carotid body reflexes were therefore studied in conscious atherosclerotic rabbits and a control group of normal animals breathing 100% O2, three hypoxic gas mixtures to which was added sufficient CO2 to maintain the arterial PCO2 constant, and 2% and 4% CO2 in 21% O2 and N2. When breathing room air, the atherosclerotic rabbits breathed at a higher respiratory frequency and lower tidal volume than the normal animals, although there was no difference in the respiratory minute volume. The respiratory and cardiovascular responses to hyperoxia, isocapnic hypoxia and hypercapnia were essentially the same in both groups of animals. Serial sections of the carotid bodies showed pathological changes including interstitial fibrosis in the caudal part with interstitial haemorrhages. The proximal part of the ascending pharyngeal artery, the vessel supplying the organ, and its origin from the external carotid, and the arterioles in the caudal part of the carotid body were nearly always occluded to a varying extent by atheromatous plaques. The capillaries appeared normal under light microscopy. The rostral-caudal lengths of the carotid bodies were similar in the two groups. We conclude that the peripheral arterial chemoreceptor responses in atherosclerotic rabbits are relatively normal even though the arteries to, and arterioles within, the carotid body are partly occluded.
Surfasoft, a new graft dressing.
We present our preliminary experience using Surfasoft, a new dressing material, in the management of burns following skin grafting. It was found to be a useful dressing in awkward sites where conventional dressings have many disadvantages.
A critical appraisal of "out-of-hours" radiography in a major teaching hospital.
The use of plain radiography performed outside normal working hours was studied at the Manchester Royal Infirmary to determine the costs of the service and where possible financial savings could be made. The annual cost of "out-of-hours" radiography was estimated to be in order of 250,000 pounds. During a selected 2-week period, 84% and 76% of all examinations performed on Accident and Emergency patients and inpatients, respectively, were found to be normal. Previous reports suggest that the number of radiographs requested in the Accident and Emergency department can be reduced without detriment to patients by the implementation of appropriate clinical guidelines. We consider that if similar guidelines were developed and applied to the use of out-of-hours radiography, substantial savings could be made. We estimate that in our hospital these savings could amount to 18% of the current expenditure on this service.