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Biomedical subjects

R M Jones

Publications and source records attributed to R M Jones.

At least 127 records · Page 7Linked to original sources

Attitudes towards liver transplantation in Victoria, Australia.

Liver transplantation commenced on a regular basis in Australia in 1985. This followed the first successful orthotopic transplant in Brisbane in 1985 and the setting up of a National Centre for Liver Transplantation in Sydney in 1985 with clinical transplantation beginning there in 1986. A centre was subsequently developed in Melbourne in 1988. As this procedure was perceived to be expensive, and because of discussion on rationing of medical services, the authors were prompted to test the Victorian community awareness and attitude to government funding of transplantation. One year after the establishment of the Victorian Liver Transplantation Programme, a random survey of the Victorian population and of general practitioners in Melbourne was conducted with the assistance of a professional polling company. Sixty-five per cent of the Victorian population knew liver transplantation was available in Victoria, 12% said it was not available and 23% did not know. Among general practitioners, 79% knew liver transplantation was available 14% said it was not available and 7% did not know. Eighty-eight per cent of Victorians and a similar proportion of general practitioners said the State Government should provide funding. Forty-seven per cent of the Victorian population said government should provide total funding and a further 39% funding of more than 50%. Among general practitioners, 33% said total funding should be provided and a further 46% thought that more than 50% of funding should be provided. This survey has revealed convincingly that Victorians have decided that their health care should include the expense of liver transplantation paid for by government. Awareness of the availability of the operation of liver transplantation is developing rapidly.

Attitude to Health↗

The morbidity of surgical access: a study of open versus laparoscopic cholecystectomy.

A prospective non-randomized study of 37 adult patients undergoing open cholecystectomy and 40 patients undergoing laparoscopic cholecystectomy was undertaken to test the hypothesis that surgical access alone has a significant impact on postoperative morbidity. Specifically the study examined the deterioration of pulmonary function, development of pulmonary complications, postoperative narcotic requirement and total bed stay as markers of postoperative morbidity. The results showed that significantly less deterioration of pulmonary function occurred in patients treated using the laparoscopic approach. In this group there was also significantly less requirement for postoperative narcotics, less consequent development of pulmonary complications and a shorter bed stay in hospital. The study documents the substantial impact of surgical access on postoperative morbidity and highlights the benefits of the laparoscopic 'minimal access' approach.

Adult↗

Hepatitis due to nitrofurantoin.

OBJECTIVE: To report three cases of hepatitis related to the use of nitrofurantoin. CLINICAL FEATURES: Two patients who had been taking nitrofurantoin for several years, presented with severe liver failure. In both, the drug had been continued despite evidence of liver injury. A third patient presented with acute hepatitis after six weeks of nitrofurantoin therapy. INTERVENTION AND OUTCOME: One of the patients with liver failure died and the other underwent a successful liver transplantation. The third patient recovered after withdrawal of the drug. CONCLUSION: These cases emphasise the potential for serious hepatic reactions with nitrofurantoin, the danger of continuing the drug once liver damage has occurred and the need for careful monitoring of liver function during long-term therapy.

Adult↗

Oxygen-derived free radicals and hemolysis during open heart surgery.

Reperfusion injury occurs during open-heart surgery after prolonged cardioplegic arrest. Cardiopulmonary bypass also is known to cause hemolysis. Since reperfusion of ischemic myocardium is associated with the generation of oxygen free radicals, and since free radicals can attack a protein molecule, it seems reasonable to assume that hemolysis might be the consequence of free radical attack on hemoglobin protein. The results of this study demonstrated that reperfusion following ischemic arrest caused an increase in free hemoglobin and free heme concentrations, simultaneously releasing free iron and generating hydroxyl radicals. In vitro studies using pure hemoglobin indicated that superoxide anion generated by the action of xanthine oxidase on xanthine could release iron from the heme ring and cause deoxygenation of oxyhemoglobin into ferrihemoglobin. This study further demonstrated that before the release of iron from the heme nucleus, oxyhemoglobin underwent deoxygenation to ferrihemoglobin. The released iron can catalyze the Fenton reaction, leading to the formation of cytotoxic hydroxyl radical (OH.). In fact, the formation of OH. in conjunction with hemolysis occurs during cardiac surgery, and when viewed in the light of the in vitro results, it seems likely that oxygen-derived free radicals may cause hemolysis during cardiopulmonary bypass and simultaneously release iron from the heme ring, which can catalyze the formation of OH..

Cardiac Surgical Procedures↗

Water balance and lung fluids in rats at high altitude.

A disturbed water and electrolyte homeostasis is not generally held to be a primary mechanism in the pathogenesis of acute mountain sickness (AMS) and high altitude pulmonary edema (HAPE), but the association of oliguria and weight gain with AMS and HAPE has led to the hypothesis that water retention may be a facilitative mechanism, possibly caused by an effect of hypoxia to release antidiuretic hormone (ADH). To examine the problem, normal Long-Evans rats (N) and the strain with congenital diabetes insipidus (DI) were exposed to hypobaric hypoxia (0.5 atm) for 4 days, and fluid balance in the whole animals and in their lungs was studied. Both strains reduced water intake and were oliguric on acute exposure, but the N rats gained body weight and increased lung water, while the DI rats increased neither body weight nor lung water. Neither strain increased lung blood at high altitude. The oliguria in the DI rats could not have been due to a release of antidiuretic hormone, and was attributed to the diminished water intake in both strains. The protection against HAPE in the DI rats was probably due to their more severe dehydration that exists already in normoxia, and its further increase in hypoxia, compared with N rats.

Altitude Sickness↗

Recovery characteristics using isoflurane or propofol for maintenance of anaesthesia: a double-blind controlled trial.

We studied 114 female patients (ASA 1 or 2) who were within 20% of ideal body weight and who were scheduled to undergo gynaecological laparoscopy which required supplementation with an opioid (groups IA and PA), or dental procedures which did not require opioid supplementation (groups IO and PO). A computerised package of psychomotor tests was performed before surgery. Anaesthesia was induced with propofol 2.5 mg.kg-1 and all patients received atracurium 0.3 mg.kg-1 and 67% nitrous oxide in oxygen. Patients in group IA received isoflurane 1% (inspired), and alfentanil 10 micrograms.kg-1 as a bolus and 10 micrograms.kg-1.h-1 as an infusion. Patients in group PA received propofol 9 mg.kg-1.h-1 as an infusion, decreasing to 6 mg.kg-1.h-1 after 15 min, together with alfentanil 10 micrograms.kg-1.h-1. Patients in groups IO and PO received isoflurane and propofol in the regimens described for groups IA and PA, but without alfentanil. Recovery was assessed by a blinded observer who recorded times to awakening (eye opening) and orientation (giving date of birth), and who repeated the psychomotor tests at 1, 3 and 5 h. Linear analogue scales of mood, nausea and pain were obtained and other side effects were noted in the succeeding 48 h. A matched control group of 25 females (who were not anaesthetised) underwent psychomotor testing on four occasions in order to assess the 'learning effect' of repeated recovery testing. The analysis of recovery tests did not assume a normal distribution.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Mivacurium chloride: a study to evaluate its use during propofol-nitrous oxide anaesthesia.

We assessed the neuromuscular and cardiovascular effects of mivacurium chloride, a neuromuscular blocking agent, in 33 patients during propofol-nitrous oxide anaesthesia. Neuromuscular function was assessed with supramaximal stimuli of the ulnar nerve, using surface electrodes at the wrist, with repeat trains of four. Mivacurium given as a bolus of 0.15 mg.kg-1 (ED95 x 2) was found to be haemodynamically stable. Intubating conditions assessed at 2 and 2.5 min were either good or excellent. All patients developed a block of 100% in a mean (SD) time of 105 (34) s. There were mean (SD) intervals of 12 (2.4) min before the reappearance of the first twitch of the train of four (T1) following the bolus dose, and 15.8 (3.1) min for the T1 to reach 25% of its control value (TC). Seventeen patients received an infusion of mivacurium to maintain neuromuscular blockade (T1:TC 10-20%) with a mean (SD) infusion rate of 6.9 (2.2) micrograms.kg-1.min-1. Recovery from neuromuscular blockade was assessed with spontaneous offset or augmented with edrophonium following either the initial bolus or an infusion. Following a bolus it took a mean (SD) of 26.2 (3.7) min for the fourth twitch of the train of four (T4):T1 ratio to reach 0.7. In patients receiving an infusion with spontaneous offset it took a mean (SD) time of 12.0 (2.2) min to reach the T4:T1 ratio of 0.7 from a T1:TC value of 8.8. Edrophonium significantly decreased the recovery time in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

A putative anaerobic coproporphyrinogen III oxidase in Rhodobacter sphaeroides. I. Molecular cloning, transposon mutagenesis and sequence analysis of the gene.

A mutant of Rhodobacter sphaeroides, N1, has been isolated which is incapable of photosynthetic growth and, instead of synthesizing bacteriochlorophyll, N1 excretes coproporphyrin III into the growth medium. Using conjugative gene transfer, several clones were isolated from a R. sphaeroides gene library which restored normal pigment synthesis and photosynthetic growth to N1. Using transposon Tn5 mutagenesis, the gene was located to a 1.05 kb EcoRI fragment. Sequence and transcription analysis defined the position and expression of an open reading frame of approximately 920 bp, which is proposed as the anaerobic coproporphyrinogen III oxidase dedicated to bacteriochlorophyll biosynthesis.

Amino Acid Sequence↗

Perforated peptic ulcer. A further application of laparoscopic surgery.

A case of perforated peptic ulcer in a patient with cervical myelopathy due to osteophyte cervical canal stenosis complicated by the sudden onset of abdominal pain is described. Diagnostic laparoscopy revealed a perforated peptic ulcer in the anterior wall of the duodenal cap. Laparoscopic treatment was suitable for this condition.

Aged↗

An investigation of cognitive style and alcohol/work-related problems among Naval personnel.

This study examines the relationship between cognitive style (i.e., information, normative, and diffuse orientation, and commitment) and alcohol/work-related problems. A random sample of Naval personnel (n = 2000) with less than two years of service toward their first enlistment was sent a questionnaire to assess cognitive style [1] and alcohol/work-related problems. A total of 899 respondents (45.0%) returned their questionnaires. Findings support prevention strategies that incorporate problem-solving, decision-making, and coping strategies, particularly among participants who employ diffuse problem-solving/coping strategies (lack of exploration and commitment, avoidance of problems). Correlations between cognitive style and alcohol/work-related problems are theoretically compatible. Diffuse orientation scores are positively related to both alcohol- and work-related problems, while norm and information orientation scores are negatively related to both measures. Collectively, cognitive style measures explain 11.4 percent of the variability in alcohol-related problems, and 14.0 percent of the variability in work-related problems.

Adaptation, Psychological↗

Preconditioning of heart by repeated stunning: adaptive modification of myocardial lipid membrane.

Recent studies indicate that preconditioning of a heart by repeated stunning protects it from subsequent ischemic injury. Such myocardial preservation is likely to be due to adaptive modification of lipid composition and dynamic structure of cellular membrane. To test this hypothesis, swine heart was subjected to four episodes of 5 min stunning by LAD occlusion, followed by 10 min of reperfusion after each stunning. Heart was then made regionally ischemic for 60 min by LAD occlusion, followed by 6 h reperfusion. Control heart was perfused for 60 min, followed by 60 min ischemia and 6 h reperfusion. Free fatty acids (FFA) accumulated in control heart during ischemia as expected, which was further enhanced by reperfusion. The FFA level was also enhanced during ischemia in stunned myocardium. However, this FFA level was almost restored during reperfusion. The levels of polyunsaturated fatty acids (PUFA) such as oleate, linoleate, and arachidonate followed a similar pattern. Membrane fluidity, monitored by fluorescence polarization, was decreased during ischemia and reperfusion in the unstunned heart, with the corresponding increase in microviscosity. The increased microviscosity was significantly reduced by stunning. Since FFA are presumably generated from membrane phospholipids, these results suggest that stunning may cause the incorporation of a greater proportion of PUFA in membrane phospholipids, leading to preservation of membrane phospholipids and maintaining the membrane fluidity, which may be at least partially responsible for the attenuation of ischemic reperfusion injury.

Adaptation, Physiological↗

Enhanced responses to endothelin during perfusion of ischemic myocardium. Myocardial response to endothelin.

Although endothelin perfusion at 50 pM did not reduce the coronary flow, at 200 pM, it reduced the coronary flow to a similar extent in both normal and ischemic hearts. Endothelin at 50 pM concentration enhanced the myocardial levels of inositol-1,4,5-triphosphate (IP3) and diacyl glycerol (DG) in ischemic, but not in normal, hearts. On the other hand, endothelin at 50 pM concentration enhanced the activities of membrane protein kinase C (PKC) and calmodulin dependent (CaM-PK) kinases in normal, but not in ischemic, hearts. The corresponding loss of cytosolic PKC, but not of CaM-PK, suggests a translocation of PKC and an activation of CaM-PK by endothelin. These results suggest that pM concentrations of endothelin activate membrane kinases in normal hearts and enhance PIP2, breakdown in ischemic hearts. The greater CK release and myocardial levels of nonesterified fatty acids by 200 pM concentrations of endothelin in ischemic hearts, as compared to control hearts, suggests that: (1) the myocardial cellular injury and phospholipid breakdown induced by pM concentrations of endothelin are enhanced during reperfusion; and (2) both IP3 and membrane kinase (PKC and CaM-PK) dependent biochemical cascades of reaction, rather than kinases alone, may be involved in the endothelin-induced myocardial cellular injury.

Analysis of Variance↗