Secondary patient transfer by air: an audit of 3 years' experience of the Royal Air Force in the world-wide transport of critically ill patients.
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Aerospace Medicine↗
Biomedical subjects
S J Hunter
Publications and source records attributed to S J Hunter.
A comparison of bupivacaine instillation and inguinal field block for control of pain after herniorrhaphy.
In a single-blind, randomised trial, 50 consecutive adult patients for inguinal herniorrhaphy under general anaesthesia received either an inguinal field block or bupivacaine instilled into the wound to provide postoperative analgesia. Bupivacaine instillation was found to be simple, safe and effective. The method is particularly appropriate for day-case surgery.
Adolescent↗
In vitro resorptive activity of isolated chick osteoclasts: effects of carbonic anhydrase inhibition.
A potent inhibitor of carbonic anhydrase, 5-[3-hydroxybenzoyl]thiophene-2-sulfonamide (HTS), was shown to cause a 37% reduction in the area of resorption pits formed by isolated chick osteoclasts when used at a dose of 10(-7) M. HTS at doses of 10(-9) and 10(-7) M was also effective in reducing acid formation by the osteoclasts (14 and 36%, respectively). Additionally, the effect of HTS was found to be readily reversed by removing the agent, showing that it does not exert a toxic effect on the cells. This study indicates that the inhibitory effect of HTS on bone resorption is at the level of the acid-forming mechanism in osteoclasts and supports the view that carbonic anhydrase has a central role in the process.
Acid Phosphatase↗
The pneuPAC hyperbaric variant HB: a ventilator suitable for use within a one-man hyperbaric chamber.
We describe the performance of the pneuPAC hyperbaric variant HB, a ventilator designed for use in a one-man hyperbaric chamber. The ventilator delivered minute volumes of 11-23 litre at 1 atm abs to 7.6-16 litre at 2.5 atm abs. The delivered minute volume may be controlled easily from outside the chamber by manipulation of the ventilator rate, 11.5-31 b.p.m.
Evaluation Studies as Topic↗
Two incidents of complete failure of OAV 7750 ventilators.
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Anesthesiology↗
Primary malignant melanoma of the oesophagus. Report of a case with flow cytometric DNA analysis.
Primary malignant melanoma is a very rare tumour of the oesophagus, and although this is the first case reported in a black patient in South Africa, the clinical, radiographic and histopathological features were characteristic of this malignancy. Primary oesophageal melanoma is a highly lethal tumour--fewer than 2% of patients are surviving 5 years after diagnosis. Flow cytometric DNA analysis of the resected specimen in this case revealed two populations of malignant cells, one of which had grossly abnormal DNA. Existence of two clones of malignant melanoma cells supports the observations that this tumour is biologically aggressive, radioresistant and almost always incurable.
DNA, Neoplasm↗
Age-related changes in serum insulin-like growth factor-binding proteins in women.
Plasma insulin-like growth factor-I (IGF-I) concentrations are reported to decline with advancing age. Five IGF-binding proteins (IGF-BPs) have recently been characterized in human serum, although their biological role beyond circulatory transport of IGF-I is unknown. We studied plasma IGF-I (by RIA) and serum IGF-BPs (by Western ligand blotting) in healthy elderly (n = 21) and healthy young (n = 22) women to determine if aging alters IGF-I and its high affinity BPs. Plasma IGF-I was significantly lower in the elderly than in the young group (0.78 +/- 0.08 vs. 1.22 +/- 0.11 U/ml; P less than 0.005). The number and size of IGF-BPs did not differ between age groups, but the IGF-BP binding ratios (binding of one BP fraction/binding of all fractions) for the BP-53 acid-stable complex (41.5K and 38.5K BPs), the 30K IGF-BP, and the 24K IGF-BP were all lower in the elderly than in the young group (P less than 0.01 for each fraction, elderly vs. young). In contrast, the 34K IGF-BP binding ratio was significantly greater in the elderly than in the young (0.30 +/- 0.03 vs. 0.12 +/- 0.01; P less than 0.001) and correlated closely with advancing age (r = 0.64; P less than 0.01). The changes in IGF-BPs found in the elderly are quite similar to alterations in serum IGF-BPs previously reported in GH deficiency. Since several IGF-BPs in vitro have been shown to modulate the mitogenic activity of IGF-I, the serum IGF-BP changes noted above may be important for the growth and maintenance of connective tissue, muscle, and bone during the aging process.
Adult↗
DNA ploidy in oesophageal cancer. A preliminary report.
Prognosis in oesophageal cancer is directly related to depth of invasion and lymph node metastases. However, without surgical exploration, assessment of the spread of oesophageal cancer is notoriously inaccurate and there is a need for another objective measurement of prognosis. In this study, the relationship of DNA-ploidy status to tumour length, histological appearance, extra-oesophageal spread and survival was examined in 42 patients with squamous oesophageal cancer. No correlation was found between DNA-ploidy status and tumour length or histological appearance. But the DNA-aneuploidy rate in cancers with extra-oesophageal spread was significantly greater than the rate in tumours localised to the oesophagus (P = 0.038). Short-term survival was poorer in patients with DNA-aneuploid cancers than in those with a DNA-diploid pattern. DNA analysis may prove to be a more accurate guide to prognosis in oesophageal cancer than either clinical or operative staging.
Carcinoma, Squamous Cell↗
Characterization of the cytoskeleton of isolated chick osteoclasts: effect of calcitonin.
We investigated the effects of calcitonin (CT) and parathyroid hormone (PTH) on the distribution of actin, tubulin, vimentin, and on cell size in cultured chick osteoclasts. In addition, we studied the effects of colchicine on intracellular acidity. Osteoclasts were isolated from the endosteum of 2-3-week chick tibias and were maintained under culture conditions for 5 days. The cells were treated with CT for 30 min or PTH for 60 min and were observed after immunocytochemical staining of cytoskeletal proteins. In untreated cells, actin was found in both a filamentous and a punctate staining pattern, with indented or invaginated regions free of punctate spots. The tubulin distribution in untreated cells was characterized by a pattern of microtubules radiating from the cell center and running parallel to the cell edge. Vimentin staining was usually localized to the perinuclear area. There were no changes in cytoskeletal element distribution or morphology attributable to PTH treatment. Osteoclasts treated with CT were more irregularly shaped, contained more retraction fibers, and were more rounded, with a denser array of cytoskeletal elements in the cell center. In addition, the mean area of the CT-treated cells was significantly less than that of the untreated cells. The actin distribution after CT treatment was still characterized by both a filamentous and a punctate pattern. After CT treatment, vimentin staining appeared more centrally localized than in untreated cells and tubulin staining revealed microtubules which now extended to the retracted cell margin. These results indicate that isolated osteoclasts respond to CT by significant morphological changes which are reflected in the distribution of the major cytoskeletal elements. Disruption of the microtubular system by colchicine treatment also resulted in an initial increase in intracellular acidity, suggesting the involvement of microtubules in the movement of acid-laden vesicles to the exterior.
Acid Phosphatase↗
Characterization of isolated and cultured chick osteoclasts: the effects of acetazolamide, calcitonin, and parathyroid hormone on acid production.
The effects of acetazolamide, calcitonin (CT), and parathyroid hormone (PTH) on acid production in isolated osteoclasts has been investigated. Osteoclasts were isolated from the endosteum of 3-week chick tibias and were maintained under culture conditions for 5 days. The cells were treated with acetazolamide (10 x 4 M and 10(-7) M), CT (1 mU/ml and 0.31 mU/ml) and PTH (6.5 U/ml and 0.40 U/ml) for 1, 3, 6, and 18 hr. The cells were stained with acridine orange and the intensity of fluorescence measured by a light microscope photometer. Acetazolamide treatment resulted in a steady decline in intracellular acidity, suggesting that carbonic anhydrase plays a major role in acid production in isolated osteoclasts. Treatment with PTH produced a decline in acidity at 1 hr, followed by a peak at 3 hr and then a decline at 6 and 18 hr. The transient increase in acidity may be due to activation of carbonic anhydrase by PTH. Calcitonin treatment also resulted in a decline in cell acidity which was similar, but less pronounced than that resulting from acetazolamide treatment. These results indicate that calcitonin may mediate osteoclast activity by alterations in intracellular acid production.
Acetazolamide↗
Gastric mucosal lesions induced by hemorrhagic shock in baboons. Role of oxygen-derived free radicals.
In this study we sought to define the role of oxygen-derived free radicals during ischemia and reperfusion in the production of acute damage to the gastric mucosa of baboons. The protective effect of the xanthine oxidase inhibitor, allopurinol, the superoxide scavenger, superoxide dismutase (SOD), and a long-acting SOD-albumin was determined. Mucosal damage was evaluated using light and scanning electron microscopy. Evidence for oxidative insult to the gastric mucosa was sought by measuring tissue concentrations of reduced (GSH) and oxidized (GSSG) glutathione. Gastric mucosal blood flow was estimated using the microsphere technique. A similar pattern of tissue damage was found at the end of ischemia in all three groups. Thirty minutes after reperfusion, severe mucosal damage (grade 3) increased only in the untreated control. In the two treated groups, grade 3 damage remained unchanged during reperfusion and a decrease in the percentage of moderate damage (grade 2) was seen. Both GSH and GSSG tissue concentrations were lower in the untreated controls as compared to the scavenger-treated groups, making it questionable whether GSH/GSSG tissue levels adequately reflect oxidative stress. We conclude that in our ischemia-reperfusion model the generation of oxygen-derived free radicals produces mucosal damage and prevents the restitution of moderate mucosal damage during reperfusion. In ischemia, factors other than free radicals seem to be responsible for mucosal damage. The protective effect of allopurinol and SOD was not mediated by changes in gastric mucosal blood flow.
Allopurinol↗
Towards safer intravenous regional anaesthesia.
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Anesthesia, Conduction↗
Propofol for inpatient dental anaesthesia. A comparison of propofol as sole anaesthetic agent with thiopentone and halothane for inpatient dental anaesthesia.
The induction, maintenance and recovery characteristics of propofol anaesthesia were compared with thiopentone induction and halothane maintenance in 51 spontaneously breathing, intubated patients who underwent dental surgery. Induction with thiopentone produced fewer side effects than propofol, notably pain on injection. Control of the depth of anaesthesia was better in patients who breathed halothane than in those who received intermittent bolus doses of propofol. Recovery characteristics of the two groups were similar.
Adult↗
Prevention of gastric mucosal lesions following aortic cross-clamping.
Stress ulceration is frequently encountered after cardiovascular surgery. In this study of 32 male baboons, severe gastric ischaemia was used to produce gastric stress lesions. The occurrence of these lesions was reduced by allopurinol (P = 0.03) and completely prevented by the combination of allopurinol with superoxide dismutase (P = 0.004). A shorter ischaemic period also reduced the number of lesions (P = 0.02). Concurrent with the stress lesion formation, there was a fall in mucosal glutathione and oxidized glutathione levels (P less than 0.05).
Allopurinol↗
Cross-clamping of the thoracic aorta. Influence of aortic shunts, laminectomy, papaverine, calcium channel blocker, allopurinol, and superoxide dismutase on spinal cord blood flow and paraplegia in baboons.
There is a high incidence of paraplegia associated with thoracic aortic cross-clamping, even when cardiopulmonary bypass or shunts are used. In 56 adult baboons, spinal cord blood flow (SCBF), vascular anatomy, and paraplegia rates were evaluated. Tissue blood flow was measured by radioactive microspheres. Various procedures were used to increase SCBF and to prevent ischemia-reperfusion injury. It was found that the rate of paraplegia was inversely correlated with neural tissue ischemia (SCBF) and directly correlated with reperfusion hyperemia. Two methods completely prevented paraplegia. These two methods were a thoracic shunt with occlusion of the infrarenal aorta or cerebrospinal fluid drainage plus intrathecal papaverine injection, both of which were associated with an increased SCBF. Furthermore, papaverine dilated the anterior spinal artery (ASA) (p = 0.007) and increased the blood flow through the lower ASA. Whereas procedures utilizing a calcium channel blocker (flunarizine), allopurinol, superoxide dismutase (SOD), laminectomy alone, and a thoracoabdominal shunt not perfusing the arteria radicularis magna (ARM) all failed to prevent paraplegia, allopurinol (p = 0.026) and SOD (p = 0.004) did prevent gastric stress lesions, indicating that their failure to prevent paraplegia was not due to a lack of activity. Of great clinical interest is that, if a shunt is used and the ARM is perfused, infrarenal aortic cross-clamping increases SCBF, thus preventing paraplegia. Intrathecal application of papaverine proved to be even more effective in increasing SCBF and also completely prevented paraplegia. As this is a safer procedure than the insertion of shunts, this is the method of choice for the prevention of paraplegia associated with thoracic aortic cross-clamping. The preliminary trial using intrathecal papaverine in human beings has thus far shown no adverse side effects from the drug, and no paraplegia has occurred.
Allopurinol↗
Nucleoside incorporation as a function of hormone levels during the early phases of estrogen-induced genesis of medullary bone in the Japanese quail, Coturnix coturnix.
The sequence of changes in RNA synthesis during the early phases of genesis of medullary bone induced in male Japanese quail by estrogen treatment was studied by 3H-uridine uptake. Analyses of plasma estrogen and testosterone were done by radioimmunoassay at 12, 24, 38 and 61 h. A dose of 5 mg kg-1 estradiol-17 beta was found to stimulate the same 3H-uridine uptake 15 h after hormone treatment as a dose of 20 mg kg-1 of estradiol valerate. The uptake of 3H-uridine rose as the dose of estradiol-17 beta increased. Plasma estrogen levels, which were highest 12 h after injection, declined sharply during the next 12 h, returning to control levels between 38 and 61 h. Testosterone levels declined after estrogen administration and remained below control values at all time points. Following estrogen administration, 3H-uridine uptake declined from control values for the first 8 h. Twelve hours after hormone administration control levels were again reached, with maximum 3H-uridine uptake occurring 16 h after hormone treatment. The 16-h maximum was followed by a steady decline to below control levels at 20, 24 and 28 h, the time at which the experiment was discontinued. Maximum 3H-uridine uptake following estrogen stimulation is similar to that observed for the stimulated immature rat uterus.
Animals↗
The development of medullary bone: a model for osteogenesis.
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Animals↗