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Biomedical subjects

P McMaster

Publications and source records attributed to P McMaster.

At least 163 records · Page 9Linked to original sources
PubMed1993

Development of indications and results during 10 years of orthotopic liver transplantation.

Liver transplantation has rapidly emerged in recent years from an uncommon experimental procedure, limited to a few centers, to become a major international effort to support patients with advancing and decompensating liver disease. The excellent results which can be achieved with optimal timing and expert clinical management are now no longer in doubt. The greatest emphasis now must be on obtaining suitable high quality donors at the right time to give the patient the best opportunity to make a full and complete recovery.

Blood Transfusion↗
PubMed1993

Factors influencing blood transfusion during adult liver transplantation.

From 1982 to 1990, 300 adults received liver transplants in Birmingham UK with a median intraoperative blood transfusion rate of 23.5 units for the first 50 patients falling to 8 units for the last 50. The major factors in the reduction of blood usage were the experience of the team, the use of venovenous bypass and the use of an argon beam coagulator. Univariate analysis of preoperative factors in an attempt to predict patients at risk of excessive intraoperative transfusion showed that levels of serum sodium, urea, creatinine, haemoglobin, patient weight and the presence of ascites were significantly related to the quantity of blood transfused, although stepwise discriminant analysis showed that only blood urea and platelet count had an independent association with transfusion. The final model was poorly predictive of intraoperative transfusion requirements. Technical factors rather than patient-related factors are more important in the control of intraoperative bleeding in newly established transplant programmes.

Adolescent↗
PubMed1992

Hepatic transplantation in children using reduced size allografts.

The shortage of paediatric liver donors has led to the use of reduced size hepatic allografts. Between July 1987 and July 1990, 30 reduced size orthotopic liver transplantations were performed in 24 children aged between 3 months and 7 years. All patients were in advanced chronic or acute liver failure and were considered unlikely to survive for long enough for a size-matched donor to become available. The most common indication was biliary atresia. The median intraoperative blood loss was 75 (range 13-1015) ml kg-1. Nine patients have died and seven have undergone retransplantation, four successfully. Seven patients had portal vein hypoplasia with a high graft failure rate due to ischaemic infarction. There was significant morbidity from biliary tract complications, leading to further operations in four cases. The 1-year actuarial survival rate was 62 per cent.

Biliary Atresia↗
PubMed1992

Long-term immunosuppression after liver transplantation: are steroids necessary?

Steroid therapy was withdrawn in 85% of 152 orthotopic liver transplant recipients with grafts surviving for more than 3 months, and 87% of these remained steroid-free. Steroid therapy was restarted in 8% for reasons other than rejection. The most common was conversion of immunosuppression because of cyclosporine nephrotoxicity. The incidence of rejection after steroid withdrawal was low: 3.8% for chronic rejection (CR) and 4.5% for acute rejection. Only 3 grafts (1.9%) were lost because of CR. No risk factors have been identified for the development of CR after steroid withdrawal, but a protective role for azathioprine has been suggested.

Adolescent↗
PubMed1991

Primary sclerosing cholangitis: surgical options, prognostic variables and outcome.

The natural history of primary sclerosing cholangitis (PSC) is poorly defined and its management remains controversial. Forty-eight symptomatic patients (median age 39 years, range 8-67 years; 30 male) with PSC were reviewed retrospectively. Thirty patients had inflammatory bowel disease. Four patients (8 per cent) developed or had an associated malignancy. Twenty-one (44 per cent) died; overall 5 year actuarial survival was 30 per cent. Twenty-three patients had 27 non-transplant related biliary operations (16 patients specifically for PSC) of whom 12 died. Serum bilirubin was the only parameter to improve after biliary surgery. Seventeen patients (35 per cent) underwent orthotopic liver transplantation (OLT) of whom nine are currently alive (1 year projected survival of 55 per cent). Previous biliary surgery correlated with a poor outcome (P less than 0.0001) after OLT. Being male, presence of cirrhosis, duration of symptomatic disease (greater than 3 years) and a serum bilirubin level greater than 100 mumol/l at presentation, were independently associated with a poor outcome (P less than 0.05). These data provide evidence that PSC is a progressive disease and conventional surgical options have little influence on the outcome. Previous biliary surgery adversely affects outcome following OLT. For progressive liver disease, liver transplantation should be considered the treatment of choice.

Adolescent↗
PubMed1991

Vanishing bile-duct syndrome following liver transplantation--is it reversible?

Loss of bile ducts is a characteristic feature of chronic rejection in the liver allograft (also known as irreversible rejection and vanishing bile-duct syndrome). Typically, this occurs as a progressive lesion resulting in irreversible damage and graft failure requiring retransplantation. In this study, we describe 6 patients who developed a transient loss of bile ducts following liver transplantation. This occurred in a series of 138 patients who underwent the first 160 liver transplant operations in the Birmingham Liver Transplant Programme (incidence = 4.4% of patients, 3.7% of grafts). Forty needle biopsies were obtained from the 6 patients between 6 and 1303 days after transplantation. Thirteen specimens, taken between 8 and 1253 days posttransplant (median 98 days) showed an absence of bile ducts in more than 50% of portal tracts. Other histologic features of chronic rejection, inflammatory bile-duct lesions, perivenular cholestasis, and hepatocyte dropout were also seen in these biopsies, and severe cholestasis was present biochemically (median serum bilirubin level 240 mumol/L). The histologic and biochemical changes were thought to be compatible with a diagnosis of chronic/irreversible rejection, but the decision to carry out retransplantation was deferred on the basis of stable and, subsequently, improving biochemistry. Follow-up biopsies showed recovery of duct loss and other histologic abnormalities. All 6 patients are currently alive and well with good graft function. It is concluded that a transient, reversible bile-duct loss can occur after liver transplantation and that cases with this condition are indistinguishable from those who subsequently develop irreversible graft damage. In view of the risks associated with additional immunosuppression and/or retransplantation, caution is advocated in the interpretation of ductopenia in posttransplant liver biopsies. We suggest that the term "early chronic rejection" might be appropriate to describe cases in which a definite diagnosis of irreversible graft damage cannot be made.

Adolescent↗
PubMed1991

Role of endoscopic retrograde cholangiopancreatography after orthotopic liver transplantation.

Twelve of 178 (7%) liver transplant patients underwent endoscopic retrograde cholangiopancreatography (ERCP) after transplantation. The indications for ERCP were persistent or late onset cholestasis, recurrent cholangitis, and suspected biliary leaks or strictures. The time between transplantation and ERCP ranged from 44 to 330 days (median 153 days). Biliary complications diagnosed by ERCP included biliary sludge in the form of casts, calculi, or debris (n = 7); bile leaks (n = 2); a biliary stricture (n = 1), and complete biliary obstruction (n = 1). One patient had a normal cholangiogram after transplantation. Biliary sludge was detected by ultrasound before ERCP in only one of six patients. Eight patients underwent endoscopic papillotomy, followed by clearance of biliary sludge in four and dilatation of a biliary stricture in one. Two patients bled after papillotomy but neither required surgical intervention. At a median follow up of 1.2 years (range 0.5-2.8 years), nine patients are well and three have died. ERCP provides both accurate diagnosis of biliary complications after liver transplantation and treatment that obviates the need for additional surgery in selected patients.

Adult↗
PubMed1991

Central pontine myelinolysis in liver transplantation.

Five cases of central pontine myelinolysis (CPM) were detected by neuropathological examination in a series of 50 patients coming to necropsy after liver transplantation. One patient also had extrapontine myelinolysis. In no case was the diagnosis made during life. Only two patients showed rapid rises in serum sodium concentrations. The incidence of hyponatraemia, before and after transplantation, and rapid rises in serum sodium in patients with CPM was significantly greater than in the 45 patients showing no neuropathological evidence of CPM. It is concluded that there is a high incidence of CPM after liver transplantation, that clinical diagnosis is difficult, and that there is no simple direct correlation between rapid serum sodium changes and the development of this condition. Avoidance of major electrolyte fluctuations at the time of liver transplantation is recommended but it must be emphasised that CPM may occur without any rapid rise in serum sodium concentration.

Adolescent↗
PubMed1991

Native and recombinant human hepatocyte growth factors are highly potent promoters of DNA synthesis in both human and rat hepatocytes.

Human hepatocyte growth factor (hHGF) has recently been expressed as a recombinant polypeptide from Chinese hampster ovary cell transfectants. Using a primary rat hepatocyte bioassay, we have tested the biological activity of recombinant hHGF and compared it with native hHGF. Dose-response curves were almost identical, with half-maximal stimulation of DNA synthesis at 1-2 ng/ml (equivalent to approximately 10 pM). S-phase labeling index was similarly enhanced and numerous mitotic cells were observed. Recombinant and native hHGF also stimulated DNA synthesis and S-phase labeling index in primary adult human hepatocytes. Human cells were more responsive than rat hepatocytes, with recombinant hHGF slightly more potent than native hHGF (half-maximal stimulation 0.3 and 0.6 ng/ml, respectively). Since HGF levels rise in patients with fulminant hepatic failure and in animals after partial hepatectomy or administration of hepatotoxins, situations where liver regeneration occurs, HGF is suggested to play a key role in regulation of hepatic growth. The high potency of the factor on human hepatocytes reinforces its candidacy as a critical mitogen in human liver growth. The availability of a recombinant hHGF opens the way for in vivo experimental studies and to the possibility of using hHGF as a clinical therapeutic agent, either alone or in combination with other factors.

Adult↗
PubMed1991

Preliminary study of indocyanine green clearance in primary biliary cirrhosis.

Indocyanine green clearance was measured in 23 symptomatic patients with primary biliary cirrhosis who were followed up for 6 months. Ten patients either died (n = 4) from their primary biliary cirrhosis or underwent liver transplantation (n = 6) during the follow-up period. Indocyanine green clearance and other liver function test results were compared between the survivors (n = 13) and those who had died or undergone transplantation (n = 10). Indocyanine green clearance, bilirubin, bile acids, albumin, and prothrombin ratio differed significantly between the two groups, whereas age, alkaline phosphatase, globulin, and aspartate aminotransferase did not. Indocyanine green clearance gave better discrimination between the two groups than the other liver function tests, including bilirubin. There was a close correlation between indocyanine green clearance and bilirubin in patients who died or were transplanted. Further studies are necessary to define whether indocyanine green clearance is clinically useful in selecting patients for transplantation and in the timing of intervention.

Adult↗
PubMed1991

Growth of normal human hepatocytes in primary culture: effect of hormones and growth factors on DNA synthesis.

Although the ability of hormones and growth factors to stimulate DNA synthesis in rat hepatocytes has been investigated extensively, no such study of human hepatocytes has been reported. Here we describe a series of experiments to identify those factors that regulate human hepatocyte DNA synthesis in vitro and which therefore may play a role in the control of human liver regeneration. Human hepatocytes were isolated from normal liver tissue obtained after graft reduction for transplantation into pediatric recipients. Cells were maintained in culture for up to 5 days, and DNA synthesis was determined. Hydroxyurea reduced [3H]thymidine incorporation into DNA by 95%, indicating replicative DNA synthesis. As previously found with rat hepatocytes, epidermal growth factor and transforming growth factor-alpha stimulated DNA synthesis at low nanomolar concentrations; transforming growth factor-alpha was slightly more potent. Although the overall rate of thymidine incorporation was lower than that for rodent cells, human hepatocytes were sensitive to lower concentrations of these growth factors, and the degree of stimulation was similar. Conversely, transforming growth factor-beta inhibited DNA synthesis at low picomolar levels. By contrast (unlike rat hepatocytes), arginine-vasopressin failed to initiate or potentiate DNA synthesis in human cells. These data indicate that normal human hepatocytes can respond to low concentrations of growth promoters or inhibitors, previously shown to have activity on rat hepatocytes. These factors may then play a role in control of human liver growth. However, important species differences are apparent, highlighting the limitations of extrapolating from animal studies to humans.

Animals↗