Temporal changes in brain volume and cognition in a randomized treatment trial of vascular dementia

OBJECTIVE

To measure changes in brain and ischemic volume over time by magnetic resonance imaging (MRI) as part of a randomized treatment trial of vascular dementia.

METHODS

Participants who met criteria for vascular dementia underwent comprehensive neurological and neuropsychological testing on entrance, during, and at completion of the 1-year study. For those centers who had easily available MRI, MRI of the brain was to be performed on entry and completion of the study. Image analysis was performed on all balanced and T2-weighted MR films to determine ventricular, sulcal, ischemic, and hemispheric brain volumes.

RESULTS

Of the 105 patients who met the criteria for vascular dementia, 40 had a baseline MRI study that met protocol requirements and was of excellent image quality. The baseline ventricular volume in these 40 patients with high-quality MR correlated with most measures of cognitive and behavioral function, including the total Alzheimer's Disease Assessment Score (ADAS) (r = 0.51, P = .0024), as well as activities of daily living (r = 0.61, P = .0002). The baseline ischemic brain volume correlated well only with the gait and postural stability scale (r = 0.74, P = .009). Of the 40 participants, 25 had MRI studies at baseline and at completion of the study that were comparable and of excellent image quality. For these 25 patients, the mean ventricular volumes increased by 9% over the study year (P = .001) and the mean ischemic brain volume increased by 18% (P = .01). Temporal changes in the sulcal and nonischemic brain volume did not reach significance. None of the 14 clinical score measures changed significantly between baseline and completion of the study in these 25 patients.

CONCLUSION

In summary, ventricular volume correlated well with cognitive measures in patients with vascular dementia and was a more sensitive marker for change during the study year than the clinical scales used in this study. This study also points out the practical limitations of brain imaging as a surrogate measure of clinical outcome in multicenter randomized treatment trials of brain disease.

An experimental study of tolerance among alcohol dependent individuals

BACKGROUND & OBJECTIVES

Continued alcohol use leads to tolerance, however, some dependent individuals lose tolerance despite continued alcohol consumption. The exact mechanism for this is not known. This study evaluated tolerance in alcohol dependent patients in a treatment centre using multiple measures.

METHODS

Male patients with alcohol dependence (DSM III R criteria) were chosen and detoxified in an inpatient setting. On day 14 of detoxification, each subject was given ethanol (0.75 g/kg body wt) mixed in an equal amount of placebo (cola) drink once and an equivalent amount of placebo (cola) during the other occasion in a single blind, randomised, cross over manner. Assessment of each subject was made using multiple measures (clinical, neuro-psychological tests, scales for subjective effect and blood alcohol levels), 30 min after intake of each drink.

RESULTS

The subjects (n = 26) did not very under the two conditions (alcohol/placebo) as regards subjective effects, tests on logical memory and Bender Gestalt test (BGT). Cognitive screening scores though different under the two conditions, were within the normative range. Of these 26 subjects, 50 per cent showed clinical signs of intoxication after consumption of alcohol. These two groups (impaired vs unimpaired) were comparable on all base-line clinical parameters, assessment of euphoria and sedation, and various neuropsychological tests except BGT under the two conditions (placebo/alcohol). The non-tolerant (impaired) group scored significantly (P < 0.05) worse on BGT after alcohol consumption.

INTERPRETATION & CONCLUSIONS

The study suggests that clinical tests were more sensitive in detecting intoxication. Further studies are needed to understand the mechanism of loss of tolerance.

Response to varicella immunization in pediatric liver transplant recipients

BACKGROUND

Individuals undergoing therapeutic immunosuppression are at risk of severe varicella-zoster virus (VZV) infection, particularly those without evidence of previous infection.

METHODS

Eleven children, median age 10 months (range 5.5 months to 7 years and 9 months) received one dose of varicella vaccine (Varilrix, SmithKline Beecham plc, UK) before liver transplantation (median interval 95 days, range 40-289 days). The serological response to varicella vaccine was evaluated retrospectively and matched with the outcome and management of any subsequent exposures to VZV.

RESULTS

Three children responded postimmunization, six children showed no response, and in two children the outcome was difficult to interpret having received blood products. Four children required varicella-zoster immunoglobulin prophylaxis posttransplantation, two of whom developed mild chickenpox.

CONCLUSIONS

Only 3 of 11 children developed a clear antibody response to varicella vaccine. Administration of varicella vaccine did not affect the management of subsequent VZV exposures.

Bone marrow failure in children with acute liver failure

BACKGROUND

Aplastic anemia is a rare but well-recognized complication of acute hepatitis and acute liver failure. The cause is unknown, and the condition is fatal without bone marrow recovery. Treatment includes immunosuppression regimens or bone marrow transplantation. The purpose of this study was to investigate the incidence, cause, treatment, and outcomes of this disorder in children.

METHODS

Retrospective chart review of 75 patients with acute liver failure in a major pediatric liver center.

RESULTS

Eight patients had evidence of bone marrow failure. Of those, six had aplastic anemia, and two had transient bone marrow suppression. There were five boys, median age 57 months (range, 36-132 months). Two had parvovirus B19, six had non-A, non-B, non-C hepatitis. Five underwent liver transplantation: auxiliary in one, orthotopic in four. The interval between initial symptoms and development of aplastic anemia and/or bone marrow suppression was 21 to 99 days (median, 39 days). Four patients with aplastic anemia received intravenous antithymocyte globulin (ATG) or antilymphocyte globulin (ALG). Median recovery period of granulopoiesis was 62 days (range, 27-115 days). Two made a full recovery, one had myelodysplasia, and one with unresponsive disease died of septic complications. Four did not receive ATG/ALG, two had aplastic anemia, and two had bone marrow suppression. Three underwent liver transplantation, and all four resumed granulopoiesis. One child who underwent liver transplantation died of sepsis with chronic rejection. Median recovery of granulopoiesis was 99 days (range, 20-153 days).

CONCLUSIONS

Bone marrow failure occurs in 10.7% of children with acute liver failure. It sometimes occurs in association with non-A, non-B, non-C hepatitis and parvovirus B19 infection. Treatment with ATG/ALG is successful and is well tolerated in most cases.

Recurrence of Langerhans cell histiocytosis in the graft after pediatric liver transplantation

Two girls were diagnosed with Langerhans cell histiocytosis (LCH) at the age of 16 and 7 months and developed end stage chronic liver disease related to LCH-induced sclerosing cholangitis at 28 and 8 months, respectively. They received liver transplants at 34 and 14 months of age. Five months post-orthotopic liver transplantation (OLT) one of the patients developed posttransplant lymphoproliferative disease, successfully treated with a combination of surgery and reduction of immunosuppression. Fourteen months post-OLT she developed diabetes insipidus, bilateral ear discharge, and new osteolytic lesions. After transplantation both girls had mild skin reactivations of LCH, requiring minimal steroid increments. At 60 and 5 months post-OLT intrahepatic LCH recurrence was diagnosed on the basis of abnormal biliary enzymes and presence of Langerhans cells in the grafts. Initial cholangiography in both patients was unremarkable. LCH activity was controlled by maintenance chemotherapy with vinblastine, etoposide, and prednisolone. Ten months after reappearance of LCH in the liver graft a follow-up cholangiography in one of the girls demonstrated a low grade cholangiopathy. Residual elevation of liver enzymes probably represents an ongoing pathogenic process.

Mycobacterium tuberculosis infection in pediatric liver transplant recipients

OBJECTIVES

To study the incidence, clinical presentation, management, complications and outcome of tuberculosis in pediatric liver transplant recipients.

METHODS

A retrospective review of the medical records of children who underwent liver transplantation between 1991 and 1998.

RESULTS

Mycobacterium tuberculosis infection occurred in 6 of 254 (2.4%) children undergoing liver transplantation between 1991 and 1998. Cough, pyrexia and poor appetite were common presentations; one-half had normal chest radiographs. The median time to confirmation of diagnosis was 8 months (range, 1 to 17 months). Tests contributing to diagnosis included: Ziehl-Neelsen (ZN) stain (2 patients), M. tuberculosis polymerase chain reaction (1 patient), Mantoux test (1 patient) and histopathology (4 patients). Family health screening was productive for 4 patients. Duration of treatment varied from 9 to 18 months. Isoniazid-induced hepatitis was observed in 2 patients but resolved with dose reduction. Two patients died while receiving treatment, one of Klebsiella spp. septicemia and the other of pulmonary hemorrhage.

CONCLUSIONS

Tuberculosis after liver transplantation has a significant morbidity and mortality. Pretransplantation a personal and family history of tuberculosis must be sought, and screening of patients and their families should be considered. Standard regimens incorporating isoniazid and rifampin are effective, but regular monitoring of liver function is essential to detect drug-induced hepatotoxicity.

Isolated liver transplant and sequential small bowel transplantation for intestinal failure and related liver disease in children

Liver dysfunction is a well-recognized complication of intestinal failure in children. Advances in total parenteral nutrition (TPN) have allowed these children to survive while their intestinal tract gradually adapts. Unfortunately TPN may lead to cholestatic liver disease particularly in the young children. Progression of liver disease is associated with a poor prognosis and is an indication for small bowel transplantation. We report our experience of orthotopic liver transplantation in four children with short gut and sequential liver and small bowel transplantation in one child. All children had TPN-related liver failure. Causes of intestinal failure included necrotising enterocolitis (n=2), gastroschisis (n=1), intestinal atresia (n=1), and megacystic, microcolon syndrome (n=1). At the time of liver transplantation the children's mean age was 10.9 months (2.5-24) and weight 6.7 kg (4.8-10.1). The mean serum bilirubin was 522 micromol/liter (299-823), aspartate transaminase 423 IU/liter (49-1024) and international normalized ratio 2.8 (2-3.9). There were two deaths both from respiratory failure secondary to adenovirus pneumonia including the child who received a sequential small bowel transplant. Three children with isolated liver grafts are alive and off TPN at 20 months (mean) follow up (range 6-35). Isolated orthotopic liver transplantation has a role in selected children with intestinal failure, particularly those with short but normally functioning gut and progressing with satisfactory intestinal adaptation but developing liver disease. Those children with TPN-related liver disease and unadapted gut or irreversible intestinal disease need combined liver and small bowel transplantation. Sequential small bowel transplantation is feasible after orthotopic liver transplantation and may provide an option for the child with terminal liver and small bowel failure.

Size reduction of small bowels from adult cadaveric donors to alleviate the scarcity of pediatric size-matched organs: an anatomical and feasibility study

BACKGROUND

Small bowel transplantation in children weighing less than 10 kg is hindered by the lack of size-matched donors. The ability to create reduced size small bowel grafts from adult cadaveric donors suitable for use in young children has been studied.

METHODS

Volumetric assessment of computed tomography scans were used to evaluate abdominal cavity and small bowel volumes in children. Small bowels were retrieved from adult cadaveric donors and reduced in size.

RESULTS

Computed tomography studies of the abdominal cavity showed that the mean volume available for a small bowel graft was 260 ml in children less than 5 kg (n = 5) and 460 ml in children weighing 5-10 kg (n = 5). Fifteen small bowels were successfully reduced to provide an ileal graft of one meter while keeping the whole length of the superior mesenteric artery and vein after their dissection in the proximal part of the mesentery. The mean volume of the grafts created was 270 ml in seven thin patients (body mass index [BMI] <25), 390 ml in five preobese patients (25< BMI<30), and 490 ml in three obese patients (BMI>30). Mesenteric transillumination in thin donors allowed safe dissection and complete hemostasis. No diameter reduction was required. Technical modifications permitted the creation of two grafts, one ileal and the other jejunal from a single donor. Volumetric and surgical data show that implantation of up to two meters of ileum from a thin adult weighing up to 80 kg is feasible in children weighing less than 10 kg.

CONCLUSION

Size reduction of adult cadaveric small bowels can provide suitable grafts for children of less than 10 kg and could expand the potential pool of donors for these patients.

Inhibition by human embryos of mouse granulosa cell progesterone production: development of a sensitive bioassay

Reproduction technologies could be improved by the development of methods to evaluate oocyte or embryo quality in a non-invasive, quantitative manner. Since human embryos secrete a factor that inhibits granulosa cell progesterone production, an interspecies bioassay was established to investigate whether the presence of this progesterone-inhibitory factor (PIF) in human embryo-conditioned (HEC) media is related to the health and developmental capacity of the embryos. Oocytes were microsurgically removed from oocyte-cumulus complexes isolated from superovulated mouse ovaries, and the oocytectomized complexes were cultured in HEC media in the presence of follicle stimulating hormone and testosterone. Progesterone accumulation in the media was determined by radioimmunoassay. Despite the potential limitations of very small volumes of HEC media to evaluate, and the need to freeze these media at the source, the bioassay was able to detect PIF activity in HEC media. Most embryos produced PIF activity, but the degree of inhibition was not correlated with the ability of oocytes to be fertilized, nor with embryo morphology or ability to cleave and develop after transfer. These results demonstrate that secretion of PIF by human embryos can be measured by this bioassay and that human PIF can inhibit murine granulosa cell steroidogenesis; however, PIF activity is not correlated with human embryo quality or developmental competence.

Oral absorption of tacrolimus in children with intestinal failure due to short or absent small bowel

We describe two children with intestinal failure due to short or absent small bowel who underwent isolated liver transplantation for liver disease related to parenteral nutrition. Both received reduced-size liver grafts whilst awaiting a suitable small bowel donor. Immunosuppressive therapy was based on oral tacrolimus and intravenous steroids. Therapeutic levels of tacrolimus were achieved at low dosage of 0.14-0.28 mg/kg per day. Median and mean blood tacrolimus levels were 9.9 and 13.7 ng/ml (range 4.9-42.3 ng/ml) in case 1 and 5.8 and 7.2 ng/ml (range 1-30 ng/ml) in case 2 before small bowel transplantation, respectively. Following small bowel transplantation, levels were 17.1 and 20.1 ng/ml (range 9.2-30 ng/ml), with oral doses of 0.54-1.35 mg/kg per day. Both children died of adenovirus pneumonia, with functioning grafts. Our experience demonstrates that effective levels of immunosuppression can be achieved by oral administration of tacrolimus in children with short or absent small bowel.

Oral absorption of tacrolimus in children with intestinal failure due to short or absent small bowel

We describe two children with intestinal failure due to short or absent small bowel who underwent isolated liver transplantation for liver disease related to parenteral nutrition. Both received reduced-size liver grafts whilst awaiting a suitable small bowel donor. Immunosuppressive therapy was based on oral tacrolimus and intravenous steroids. Therapeutic levels of tacrolimus were achieved at low dosage of 0.14-0.28 mg/kg per day. Median and mean blood tacrolimus levels were 9.9 and 13.7 ng/ml (range 4.9-42.3 ng/ml) in case 1 and 5.8 and 7.2 ng/ml (range 1-30 ng/ml) in case 2 before small bowel transplantation, respectively. Following small bowel transplantation, levels were 17.1 and 20.1 ng/ml (range 9.2-30 ng/ml), with oral doses of 0.54-1.35 mg/kg per day. Both children died of adenovirus pneumonia, with functioning grafts. Our experience demonstrates that effective levels of immunosuppression can be achieved by oral administration of tacrolimus in children with short or absent small bowel.

Liver transplantation for glycogen storage disease types I, III, and IV

Glycogen storage disease (GSD) types I, III, and IV can be associated with severe liver disease. The possible development of hepatocellular carcinoma and/or hepatic failure make these GSDs potential candidates for liver transplantation. Early diagnosis and initiation of effective dietary therapy have dramatically improved the outcome of GSD type I by reducing the incidence of liver adenoma and renal insufficiency. Nine type I and 3 type III patients have received liver transplants because of poor metabolic control, multiple liver adenomas, or progressive liver failure. Metabolic abnormalities were corrected in all GSD type I and type III patients, while catch-up growth was reported only in two patients. Whether liver transplantation results in reversal and/or prevention of renal disease remains unclear. Neutropenia persisted in both GSDIb patients post liver transplantation necessitating continuous granulocyte colony stimulating factor treatment. Thirteen GSD type IV patients were liver transplanted because of progressive liver cirrhosis and failure. All but one patient have not had neuromuscular or cardiac complications during follow-up periods for as long as 13 years. Four have died within a week and 5 years after transplantation. Caution should be taken in selecting GSD type IV candidates for liver transplantation because of the variable phenotype, which may include life-limiting extrahepatic manifestations. It remains to be evaluated, whether a genotype-phenotype correlation exists for GSD type IV, which may aid in the decision making.

CONCLUSION

Liver transplantation should be considered for patients with glycogen storage disease who have developed liver malignancy or hepatic failure, and for type IV patients with the classical and progressive hepatic form.

Intestinal absorption and permeability in paediatric short-bowel syndrome: a pilot study

BACKGROUND

Sugar absorption tests are an effective, noninvasive way to assess intestinal permeability. The role of intestinal barrier integrity in complications and outcome of short-bowel syndrome is not known. The purpose of the study was to evaluate whether such tests provide information on the status of intestinal mucosa of these patients.

METHODS

Six children with short-bowel syndrome--median age, 12 months, and median small bowel length at birth, 30 cm--had a sugar test with 3-o-methyl-D-glucose, D-xylose, D-rhamnose, and melibiose approximately 2 months after operation. The melibiose/L-rhamnose ratio was used as an index of permeability, and percentages of 3-o-methyl-D-glucose and D-xylose absorbed were used as indices of absorption. Parenteral nutrition requirement, bowel length, liver disease, recent sepsis, and bacterial overgrowth were recorded.

RESULTS

Three patients had increased permeability, and all of them had had a recent episode of sepsis and severe liver disease. All subjects had malabsorption of 3-o-methyl-D-glucose, and five of six had malabsorption of D-xylose and L-rhamnose. The absorption of 3-o-methyl-D-glucose correlated with bowel length (r2 = 0.78; P = 0.04), whereas the absorption of D-xylose correlated with parenteral requirement (r2 = 0.66; P = 0.04) at that time.

CONCLUSIONS

Increased permeability was observed in three of six patients with short-bowel syndrome associated with a recent episode of sepsis and severe liver disease. Other indices of malabsorption correlated significantly with different clinical features of the disease. A prospective larger scale study in a homogeneous population is indicated to assess at multiple points during the disease course whether the test can be helpful in the management of these patients.

Cytochrome P450 (P450) isoenzyme specific dealkylation of alkoxyresorufins in rat brain microsomes

Characterization of xenobiotic metabolizing cytochrome P450s (P450s) was carried out in rat brain microsomes using the specific substrates, 7-pentoxy- and 7-ethoxyresorufin (PR and ER), metabolized in the liver by P450 2B1/2B2 and 1A1/1A2 respectively and 7-benzyloxyresorufin (BR), a substrate for both the isoenzymes. Brain microsomes catalysed the O-dealkylation of PR, BR and ER in the presence of NADPH. The ability to dealkylate alkoxyresorufins varied in different regions of the brain. Microsomes from the olfactory lobes exhibited maximum pentoxyresorufin-O-dealkylase (PROD), benzyloxyresorufin-O-dealkylase (BROD) and ethoxyresorufin-O-dealkylase (EROD) activities. The dealkylation was found to be inducer selective. While pretreatment with phenobarbital (PB; 80 mg/kg; i.p. x 5 days) resulted in significant induction in PROD (3-4 fold) and BROD (4-5 fold) activities, 3-methylcholanthrene (MC; 30 mg/kg; i.p. x 5 days) had no effect on the activity of PROD and only a slight effect on that of BROD (1.4 fold). MC pretreatment significantly induced the activity of EROD (3 fold) while PB had no effect on it. Kinetic studies have shown that this increase in the activities following pretreatment with P450 inducers was associated with a significant increase in the velocity of the reaction (Vmax) of O-dealkylation. In vitro studies using organic inhibitors and antibodies have further provided evidence that the O-dealkylation of alkoxyresorufins is isoenzyme specific. While in vitro addition of alpha-naphthoflavone (ANF), an inhibitor of P450 1A1/1A2 catalysed reactions and antibody for hepatic P450 1A1/1A2 isoenzymes produced a concentration-dependent inhibition of EROD activity, metyrapone, an inhibitor of P450 2B1/2B2 and antibody for hepatic P450 2B1/2B2 significantly inhibited the activity of PROD and BROD in vitro. The data suggest that, as in the case of liver, dealkylation of alkoxyresorufins can be used as a biochemical tool to characterise the xenobiotic metabolising P450s and substrate selectivity of P450 isoenzymes in rat brain microsomes.

Induction of rat brain and liver cytochrome P450 1A1/1A2 and 2B1/2B2 isoenzymes by deltamethrin

Deltamethrin, an α-cyano type II pyrethroid, administered orally (5, 10 and 15 mg/kg body weight for 7 consecutive days or at 5 mg/kg for further 15 and 21 days) to young albino Wistar rats (approximately 8 weeks old) produced a dose- and time-dependent increase in the activity of cytochrome P450-dependent 7-ethoxyresorufin-O-dealkylase (EROD) and 7-pentoxyresorufin-O-dealkylase (PROD) in rat liver and brain. However, significant induction in the enzyme activities was observed at higher doses or prolonged exposure. The magnitude of induction in rat liver microsomes was less at 15 mg/kg dose as compared to 10 mg/kg dose. Western blot analysis revealed a similar dose-related and time-dependent increase in the expression of P450 2B1/2B2 and 1A1 isoenzymes as indicated by the increased cross-reactivity of liver microsomes isolated from deltamethrin-treated animals with anti-P450 2B1/2B2 and 1A1. Inhibition of EROD and PROD observed after in vitro addition of anti-P450 2B1/2B2 and 1A1/1A2 or organic inhibitors, metyrapone and α-naphthoflavone, to the brain and liver microsomes of deltamethrin-pretreated animals (5 mg/kg×21 days), further provided support that the induction observed in the EROD and PROD activity in brain is due to the increased expression of P450 2B1/2B2 and 1A1/1A2, while, in the liver, isoenzymes other than these are also involved.

Auxiliary partial orthotopic liver transplantation for Crigler-Najjar syndrome type I

OBJECTIVE

To determine if auxiliary partial orthotopic liver transplantation (APOLT) has the long-term potential to correct the underlying abnormality in Crigler-Najjar syndrome type 1 (CNS1) without the need for total liver replacement.

BACKGROUND

Orthotopic liver transplantation has been used successfully to replace the defective enzyme in CNS1. Experimental studies have shown that only 1% to 2% of the normal hepatocyte mass is needed for bilirubin conjugation. If APOLT corrects the underlying metabolic abnormality, it has the advantage of preserving the native liver, which would serve as a "safety net" should the graft fail, and there is the potential for gene therapy in the future with possible withdrawal of immunosuppression.

METHODS

Seven APOLT procedures were performed in six recipients with CNS1. Median age at transplantation was 10.5 years. Six transplants were performed as a left auxiliary liver transplant, and one was performed as a right auxiliary liver transplant. Median serum bilirubin level at transplantation was 320 micromol/L. All patients required 12 to 16 hours of phototherapy daily before the transplant to maintain serum bilirubin levels between 250 and 350 micromol/L.

RESULTS

Median serum bilirubin level was 50 micromol/L at day 5 after the transplant and 23 micromol/L at a median follow-up of 32 months. In four children, early severe acute rejection developed, requiring conversion to tacrolimus; one underwent a second transplant for chronic rejection and graft atrophy but died from lymphoproliferative disease 6 months after the second transplant.

CONCLUSIONS

This report shows that APOLT is technically feasible and provides adequate hepatocyte mass to correct the underlying metabolic abnormality in CNS1.

Suture fixation as a treatment for acute traumatic osteochondral lesions

This is a report on the treatment of traumatic osteochondral lesions with suture fixation. Equivocal results from traditional, conservative treatment modalities have resulted in a recent surge in research in this area. Literature reports of treatments for these lesions often rely on a fibrocartilage healing response that exhibits inadequate weight bearing, lubricating, and durability qualities. We describe here a method by which a large, intact osteochondral fragment over the articulating, weight-bearing portion of the patella may be repaired using suture. This method allows for the preservation of the articular topography without many of the complications seen using other fixation techniques.

Assessment of potential donors for living related liver transplantation

BACKGROUND

Living related liver transplantation has been developed as an important potential source of organs for treatment of children with acute and chronic liver disease. A single UK centre performing living related liver transplantation was established in 1993.

METHODS

Parents who were potential donors for their children for living related liver transplantation were assessed for suitability according to a protocol based on one developed and published by the University of Chicago Transplant Group. Records kept by the transplant coordinators were retrieved and data were extracted.

RESULTS

Of 64 potential donors for 32 potential recipients ten were excluded at a preliminary stage. Fourteen ultimately became donors. Of 54 parents who began evaluation 23 were finally considered to be suitable. There were 19 non-disease-related reasons for unsuitability: blood group mismatch (eight cases), size discrepancy (six), pregnancy (two), oral contraceptive medication (one), vascular anatomy variant (one) and age (one). Sixteen were unsuitable because disease was found, namely fatty liver (four), thyroid disease (two), hepatitis B positivity (two), cardiac murmur (one), anaemia (one), glucose-6-phosphate dehydrogenase deficiency (one), diabetes mellitus (one) and psychological problems (one), and three parents were affected by the same disorder as the child (Alagille syndrome, one; mitochondrial disorder, one; recurrent cholestasis, one). Three parents were rejected for more than one reason. Both parents were unsuitable for donation in 21 per cent of cases.

CONCLUSION

Parents approach living related liver transplantation with enthusiasm. They should be advised of the high chance of unsuitability, including the finding of significant pathology. The limitation of living related liver transplantation as the major source of organs for children is recognized.

Evidence for O-dealkylation of 7-pentoxyresorufin by cytochrome P450 2B1/2B2 isoenzymes in brain

O-dealkylation of 7-pentoxyresorufin (PR) was studied in rat brain to characterise the functional activity specific for cytochrome P450 2B1/2B2 isoenzymes in brain microsomes. Brain microsomes catalyzed the O-dealkylation of PR in the presence of NADPH. Pretreatment with phenobarbital (PB; 80 mg/kg body wt, i.p. x 5 days) resulted in 3-4 fold induction of pentoxyresorufin-O-dealkylase (PROD) activity while 3-methylcholanthrene (MC; 30 mg/kg body wt, i.p. x 5 days) did not produce any significant increase in enzyme activity. Kinetic studies revealed that the rate of velocity (Vmax) for the O-dealkylation of PR was significantly increased to 2.9 times higher in brain microsomes isolated from PB pretreated rats. In vitro studies using metyrapone, an inhibitor of P450 2B1/2B2 catalyzed reactions and antibody for hepatic PB inducible P450s (P450 2B1/2B2) significantly inhibited the activity of PROD in cerebral microsomes prepared from PB pretreated animals. These studies suggest that PB inducible isoenzymes of P450, i.e. P450 2B1/2B2 specifically catalyze the O-dealkylation of PR in brain microsomes.