Search PubMed⌕ Search

Biomedical subjects

A Dhawan

Publications and source records attributed to A Dhawan.

At least 55 records · Page 3Linked to original sources
PubMed1999

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

UNLABELLED: 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.

Adolescent↗
PubMed1999

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.

Adenoviridae Infections↗
PubMed1999

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.

Acute Disease↗
PubMed1999

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.

Alkylation↗
PubMed1999

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.

Adolescent↗
PubMed1999

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.

Adolescent↗
PubMed1999

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.

3-O-Methylglucose↗
PubMed1998

Hemophagocytosis: a potential complication in small bowel transplantation.

BACKGROUND: Acquired hemophagocytosis is a histiocytic proliferation associated with phagocytosis of the hemopoietic elements resulting in fever, profound pancytopenia, hepatosplenomegaly, lymphadenopathy, and coagulopathy. Acquired hemophagocytic syndrome is a specific entity that can be differentiated from malignant histiocytosis and familial hemophagocytosis. It has been associated with a variety of disorders, including immunodeficiency, infection, hemopathies, cancer, and autoimmune diseases, as well as with the period following solid organ and bone marrow transplantation. METHODS: We describe a case of a fatal outcome, due to hemophagocytosis, after small bowel transplantation in a patient with systemic lupus erythematosus. RESULTS: Hemophagocytosis secondary to systemic lupus erythematosus has been reported to have a better response to steroid therapy than that associated with infection. In this case, the association of an autoimmune disease, high levels of immunosuppression, and posttransplant sepsis may have triggered the onset of hemophagocytosis. CONCLUSION: It is suggested that patients with systemic lupus erythematosus may represent a high-risk group for developing hemophagocytosis after small bowel transplantation.

Fatal Outcome↗
PubMed1998

Gender matching and outcome after pediatric liver transplantation.

BACKGROUND: Gender is not a selection criterion for orthotopic liver transplantation (OLT), and reports in adults have shown a less favorable outcome for male recipients of female organs; the only pediatric study did not support this finding. The aim of the present study was to assess the impact of donor and recipient gender on graft and patient survival rates after pediatric OLT. METHODS: We have reviewed retrospectively 137 children (male=63; median age: 3.4 years; range: 14 days to 15 years) undergoing primary OLT from January 1991 to June 1996. These children were divided into donor-recipient gender match (M; n=64) and nonmatch (NM; n=73) groups and then classified into female to female (FF; n=30), female to male (FM; n=29), male to female (MF; n=44), and male to male (MM; n=34) subgroups. RESULTS: The M group had better graft and patient survival rates at both 1- and 5-year follow-up compared with the NM group (P<0.01). Graft and patient survival rates were different among gender subgroups (P<0.04). Graft and patient survival rates in the FM group were poorer than in the MM subgroup at both 1 and 5 years (P<0.03, P<0.01). The FM group had a higher incidence of early complications than the MM (P<0.01) group, with 50% and 33% of graft losses, respectively, related to the complications. To minimize the influence of hormonal factors, we have analyzed separately the patients younger than 12 and 10 years who had similar findings. CONCLUSION: Graft and patient survival rates after pediatric OLT are worse in gender mismatch groups, particularly for male recipients of female organs. Early complications play a role in the decreased survival rates.

Adolescent↗
PubMed1998

Small bowel bacterial overgrowth as a cause of chronic diarrhea after liver transplantation in children.

Children who have undergone liver transplantation may develop chronic diarrhea for a number of reasons. Three children who underwent liver transplantation for liver failure, all of whom had had previous biliary and intestinal surgeries and whose postoperative course was marked by signs and symptoms of intestinal malabsorption including chronic diarrhea, are described. Duodenal aspirates showed a panoply of bacterial species, and duodenal histology featured villus atrophy in two: one associated with luminal gram-positive cocci and another with acute and chronic duodenitis. Oral antibiotics cleared the symptoms. Small bowel bacterial overgrowth may need to be considered in children with chronic diarrhea after liver transplantation, especially when previous intestinal surgery has taken place. Long-term antibiotic therapy may be required to effectively eradicate the offending organisms to suppress symptoms.

Administration, Oral↗
PubMed1998

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.

Animals↗
PubMed1998

Pediatric liver transplantation.

Liver transplantation in children has become a treatment of choice for end-stage liver disease. Both graft and patient survival has significantly improved over the last two decades. The major factor contributing towards improved survival is availability of cyclosporin. Surgical innovations like living related donation has not only increased the donor pool, but has also helped patients in countries where cadaveric donation is not available. Auxiliary liver transplantation has made a significant change to the management of children with liver-based metabolic disorders and, in selected cases of acute liver failure, immunosuppression can be safely withdrawn once the native liver recovers. However, the complications associated with immunosuppression, such as nephrotoxicity, lymphoproliferative disease and viral infections, continue to be a matter of great concern. Most children with good graft function enjoy near normal quality of life.

Child↗
PubMed1998

Correlation of mucosal disaccharidase activities with histology in evaluation of rejection following intestinal transplantation.

Following intestinal transplantation, we have found that recovery from severe rejection may be difficult to identify. In this study we sought to ascertain whether concurrent determination of mucosal disaccharidase activities and histologic assessment improves the accuracy of diagnosis of rejection. Histologic changes were graded blindly using a standard set of diagnostic criteria, and these changes were compared over time to maltase, sucrase, lactase, and palatinase activities in four pediatric patients under treatment for severe rejection. The histologic criteria, which included magnitude of enterocyte loss, degree of granulation tissue, severity of villus atrophy, and frequency of apoptosis and cryptitis, were found to correlate with one another over time irrespective of outcome (r = 0.72 to r = 0.85). Enzyme activities were also correlated with each other over time (r = 0.64 to r = 0.80). However, the correlation between histologic diagnosis and enzyme activity was weaker (r = -0.48 to r = -0.57). Furthermore, neither histologic nor enzyme evaluation early in the course of rejection predicted ultimate clinical outcome. The results of this investigation show that determination of mucosal disaccharidase activity provides no additional useful information concerning efficacy of anti-rejection therapy as compared to histologic analysis alone.

Child↗
PubMed1998

Use of disodium pamidronate in children with hypercalcemia awaiting liver transplantation.

We report four children with advanced liver disease awaiting liver transplantation who developed moderately severe hypercalcemia (range: 1.65-2.40 mmol/L) while receiving total parenteral nutrition. Hypercalcemia had been unresponsive to cessation of calcium intake and therapy with loop diuretics and calcitonin. One or two intravenous doses of disodium pamidronate (35-50 mg/m2) resulted in normalization of plasma calcium concentration within 2-4 d in all four children. Pamidronate may be useful for children with hypercalcemia associated with liver disease.

Child↗