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Biomedical subjects

J F Thompson

Publications and source records attributed to J F Thompson.

At least 19 recordsLinked to original sources
PubMed1992

Potential for cadaveric organ retrieval in New South Wales.

OBJECTIVES: To measure the potential for cadaver organ retrieval in New South Wales and to determine the reasons for potential donors failing to become actual donors. DESIGN: Prospective audit of all patients dying in five hospitals in New South Wales between 1 December 1989 and 30 November 1990; quality assurance of the data by independent medical specialist and if disagreement by study committee. PATIENTS: 2879 patients (100% of all deaths) yielding 364 patients with coma and 181 potential donors. OUTCOME MEASURES: Realistic medically suitable potential donor rate, missed potential donor rate, rate of potential donors with permission refused, donor rate, reasons for realistic medically suitable potential donors failing to become actual donors. RESULTS: 2879 deaths yielded 73 medically suitable potential donors, resulting in 19 actual donors, 30 missed potential donors, 19 potential donors with permission refused, and five in whom adequate resuscitation failed. The most common reason for a potential donor failing to become an actual donor was a decision by the senior medical practitioner to withdraw or not to institute ventilatory or haemodynamic support (26/73). The second major obstacle was refusal of permission by the next of kin (17/73). Assuming that the potential donor rate was that implied by the observed donor rate (13/million population/year) the projected missed potential donor rate was 9/million population/year (95% confidence interval 4 to 15) and the projected rate of potential donors with permission refused was 13/million population/year (95% confidence interval 5 to 22). Assuming that the rate of potential donors in the study hospitals was the same as in the other New South Wales hospitals, the projected donor rate for New South Wales was 18/million population/year (10 to 26); the projected missed potential donor rate was 15/million population/year (7 to 23); and the projected rate of potential donors with permission refused was 18/million population/year (10 to 27). CONCLUSIONS: The donor rate could be increased 70%-80% by overcoming the reluctance of medical practitioners to resuscitate missed potential donors and increased further by gaining permission for organ retrieval from the next of kin.

Cadaver↗
PubMed1992

The first five years' clinical experience of the Australian National Liver Transplantation Unit.

OBJECTIVE: To report the first five years' clinical experience of the Australian National Liver Transplant Unit. PATIENTS: Three hundred and seventy patients were referred--292 adults (79%) and 78 children (21%). The major causes of liver failure in the adults were chronic active hepatitis (25%), primary biliary cirrhosis (12%), primary sclerosing cholangitis (12%), alcoholic cirrhosis (9%) and malignancy (9%). Ten per cent of patients were referred in fulminant hepatic failure. In children, the major causes were biliary atresia (40%) and inborn errors in metabolism (27%). RESULTS: Two hundred and sixty-three patients (71%) were accepted for transplantation. Of 158 (43%) accepted for early transplantation, 22 (14%) died before a donor became available. Four hundred and forty-three suitable organ donors were referred. One hundred and twenty-six patients, including 32 children (25%), received 137 grafts. Three patients with renal failure due to hyperoxaluria type 1 received concurrent renal grafts. Ninety-two patients survived (73%). For all recipients, one-year survival was 75%. Two, three and four-year survivals were 69%. One to four-year survivals for adults with benign conditions were 77%, contrasting with results for those with hepatic malignancy (40% one-year survival). Children weighing more than 8 kg had good outcomes whether they received whole grafts or reduced-size grafts (83% one to five-year survival in both cases). Infants weighing less than 8 kg who received reduced adult grafts did significantly worse (37% one to-five year survival, P less than 0.05). Thirteen (87%) of 15 patients with fulminant hepatic failure who received grafts survived. Five of these patients were given ABO-incompatible grafts and two subsequently required retransplantation. All three patients with concurrent renal and hepatic grafts survived. Rehabilitation of survivors was excellent with 95% of adults and 100% of children pursuing normal activities. Only three grafts (2%) failed with primary non-function, all in infants because of graft infarction. Graft survival was significantly worse (P less than 0.01) in patients with a positive result to a direct cross match test against the donor. CONCLUSIONS: The need for liver transplantation in Australia is approximately eight per million of population per year. More donor offers are required to prevent deaths of patients on the waiting list. Reduced-size livers are successful for children and have alleviated considerably the critical shortage of paediatric donor livers. Successful treatment by liver transplantation can now be achieved in more than 80% of patients with non-malignant liver disorders including those with fulminant hepatic failure not responding to conservative therapy.

Adolescent↗
PubMed1992

Effect of aprotinin on neutrophil function after major vascular surgery.

High-dose aprotinin reduces blood loss and blood transfusion requirements during liver transplantation and cardiac and vascular surgery. The mechanism of the haemostatic effect of aprotinin is unclear. A general effect on the anti-inflammatory response may be involved. Because leucocyte activation is part of this process, white cell function was measured in patients undergoing aortic surgery who received high-dose aprotinin therapy (n = 10) and was compared with the results from controls who did not (n = 10). The test group received an intravenous bolus (2 x 10(6) kallikrein inhibitor units) of aprotinin after induction of anaesthesia followed by continuous infusion (0.5 x 10(6) kallikrein inhibitor units/h) until the end of the operation. Blood samples were obtained before operation, immediately after surgery, and 1 and 7 days after operation. Aprotinin maintained significantly better postoperative white cell function as measured by bipolar shape formation (P less than 0.001), unstimulated nitroblue tetrazolium (NBT) reduction (P less than 0.001) and chemotaxis (P less than 0.001). Endotoxin-stimulated NBT reduction was similar in both groups, indicating that neutrophils from treated individuals retained the capacity to respond to oxidative stimuli. Aortic surgery activates neutrophils in vivo, as reflected by impaired chemotaxis and increased superoxide production. Aprotinin protects the cells against this potentially deleterious effect without affecting their ability to respond when provoked. Whether this affects leucocyte interaction with coagulation pathways and contributes to the reduction in blood loss remains to be determined.

Aged↗
PubMed1992

Thrombocytopenia post liver transplantation. Correlations with pre-operative platelet count, blood transfusion requirements, allograft function and outcome.

This study reports that thrombocytopenia is a universal phenomenon post hepatic transplantation. In 53 consecutive adult patients undergoing liver transplantation the platelet count fell by a mean of 63% (157 x 10(9)/l to 50 x 10(9)/l). The platelet count reached a nadir at Day 5 post-transplant but returned to pre-operative levels by Day 14. Non-parametric regression analysis found that pre-operative platelet count, blood transfusion requirements and maximum post-operative ALT values were independent predictors of the percentage fall in platelet count. No correlation was seen with length of graft cold ischaemic time or the use of University of Wisconsin (UW) solution. The nadir day correlated with maximum post-operative bilirubin and ALT, graft ischaemic time and use of UW solution. Maximum post-operative ALT was also an independent predictor of nadir platelet count. It was observed that patients who did not survive the hospital admission had lower post-operative platelet counts and these did not return to pre-operative levels by Day 14. The percentage fall in platelet count was an independent predictor of survival. Severe thrombocytopenia was associated with cerebral haemorrhage in 3 patients. This report provides evidence that allograft dysfunction (maximum post-operative bilirubin and/or AST/ALT) was the most consistent independent predictor of the nadir platelet count, nadir day and percentage fall in platelet count post liver transplantation although the exact mechanism(s) of the platelet changes remain uncertain.

Blood Transfusion↗
PubMed1992

Non-subungual melanomas of the hand.

The non-subungual area of the hand is a rare anatomical site for malignant melanoma, lesions in this site comprising only 0.37% of 8,584 cutaneous melanomas in the Sydney Melanoma Unit database. This is approximately the same frequency of melanoma as is found on the subungual region of the hand, which represents a much smaller surface area. Not only is the sub-site distribution on the hand unusual but in addition the histogenetic types of melanoma found on the dorsum of the hand are not those commonly encountered on sun exposed skin. In this study, comparison is made between melanomas occurring on the non-subungual areas of the hand and those on the foot, an anatomically similar surface area. Comparison is also made between melanomas arising on the dorsal non-subungual surface of the hand and those on the face, a region with an equivalent surface area and similar sun exposure. The results of surgical treatment of 31 melanomas of the non-subungual region of the hand are reviewed.

Adult↗
PubMed1992

The rational use of homologous blood in elective surgery.

The supply of homologous blood in Australia is limited, but the demand for blood and blood products is steadily increasing. Elective surgery is a major part of this demand. In many institutions the blood ordering practices for elective surgery have been haphazard. This study was undertaken to document current patterns of blood use in a major city teaching hospital. A retrospective analysis of blood ordering and transfusion for elective surgical procedures was carried out over a 12 month period. As in several previous studies, an inefficient use of blood was demonstrated. Possible strategies to rationalize the use of blood in elective surgery have been proposed. These include the use of a 'group and screen' procedure instead of a full cross-match when transfusion is unlikely to be necessary, and ordering according to a 'maximum blood order schedule' when transfusion is usually required for a procedure.

Australia↗
PubMed1992

Donor factors and liver transplantation.

There are thus many factors that may affect the suitability of a donor liver for transplantation, and a reliable, objective method of determining whether or not a liver is likely to function adequately after transplantation is urgently required. At the present time, however, the decision to use a particular donor liver remains a matter of clinical judgement. This decision will inevitably be influence both by the general availability of donor organs and by the urgency of recipient need at the time the liver becomes available, but should nevertheless be based primarily on an appreciation of the donor factors described above.

ABO Blood-Group System↗
PubMed1992

Vascular surgical training in the UK and Ireland.

Fifty-six vascular surgical trainees and 31 recently appointed consultants with an interest in vascular surgery replied to a postal questionnaire about their training. The majority fulfilled the guidelines recommended by the Vascular Advisory Committee of the Vascular Surgical Society of Great Britain and Ireland, which are--a minimum two years of higher surgical training in units with an interest in vascular surgery and a substantial and comprehensive experience of (operative) vascular surgery. However, the operative experience during training was very variable, ranging between 10 and 574 operations reported by new consultants. Minimum standards of operative experience may need to be defined. The survey also identified that training in carotid endarterectomy is sometimes deficient and noted that as much as one-third of operative experience may be gained 'out of hours' on emergency cases. To obtain this experience trainees have to work very long hours, two-thirds of senior registrars have vascular on call rotas of 1:2 or less. Imminent changes in the structure of higher surgical training and the reduction in hours worked by junior doctors may seriously affect vascular surgical training.

Education, Medical, Graduate↗
PubMed1992

Structured and unstructured grid generation.

Current techniques in composite-block-structured grid generation and unstructured grid generation for general 3D geometries are summarized, including both algebraic and elliptic generation procedures for the former and Delaunay tessellations for the latter. Citations of relevant theory are given. Examples of applications for several geometries are included.

Algorithms↗
PubMed1991

Autotransfusion.

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Blood Loss, Surgical↗
PubMed1991

Modulation of firefly luciferase stability and impact on studies of gene regulation.

Two of the reporter enzymes most commonly used in studies of eukaryotic gene expression are chloramphenicol acetyl-transferase (CAT) and firefly luciferase (Luc). CAT has a half-life of about 50 h in mammalian cells, making it useful for transient transfection assays but less suitable for assays with stable cell lines. Luc has a half-life of only 3 h in mammalian cells, making it much more responsive in stable cell lines. Luc instability arises from its sensitivity to proteolysis both in vivo and in vitro. Compounds that resemble its natural substrate, luciferin, act as effective competitive inhibitors in vitro. When these compounds (e.g., phenylbenzothiazole) are added to either prokaryotic or eukaryotic cells, more than tenfold increases in Luc activity can be observed. This increased activity results from a lower rate of degradation of the enzyme in vivo and can be mimicked in vitro as phenylbenzothiazole protects Luc from trypsin digestion while it has no effect on the rate of digestion of alkaline phosphatase.

Alkaline Phosphatase↗