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Biomedical subjects

M S Tanner

Publications and source records attributed to M S Tanner.

At least 37 records · Page 2Linked to original sources
PubMed1999

Recommended approaches for the laboratory measurement of homocysteine in the diagnosis and monitoring of patients with hyperhomocysteinaemia.

Several recent studies have indicated that an increased concentration of plasma homocysteine is an independent risk factor for the premature development of vascular disease. These important findings emphasize the need for careful selection of an appropriate analytical approach to diagnose and treat individuals who may be at risk. We compared the results obtained from the measurement of plasma total homocysteine (free + protein-bound fractions) by high-performance liquid chromatography (HPLC) with the measurement of plasma free homocystine (free fraction) by conventional ion-exchange chromatography in 10 patients with inherited defects of homocysteine metabolism and 13 obligate heterozygote individuals. This study can be used to formulate recommendations on the appropriate use of these assays in different clinical circumstances. Our results show that the concentration of total plasma homocysteine must exceed 60 mumol/L before plasma free homocystine becomes detectable by conventional ion-exchange chromatography. Similarly, assessment of the urinary excretion of homocysteine in these patients indicates that it may not become consistently detectable by conventional ion-exchange chromatography or HPLC until plasma total homocysteine exceeds 150 mumol/L. On this basis, while most patients with classical homocystinuria would be detected by analysis of plasma using conventional ion-exchange chromatography or by measurement of of the urinary homocysteine excretion, occasional patients would be missed. When monitoring patients receiving treatment for classical homocystinuria, in whom metabolic control is good, and when investigating individuals with a suspected inherited defect of cobalamin or folate metabolism, a method which measures plasma total homocysteine should be used. The identification of moderate hyperhomocysteinaemia of undefined cause investigated in relation to a history of early vacsular disease can only be identified by this approach.

Adolescent↗
PubMed1998

An animal model for copper-associated cirrhosis in infancy.

In Indian childhood cirrhosis (ICC) and related disorders of infancy, hepatic copper overload is associated with cirrhosis. Since copper administration alone has not been shown to induce cirrhosis in animals, synergy between copper and a second hepatotoxin has been suggested. This study investigates the ability of long-term exposure to copper and a pyrrolizidine alkaloid, retrorsine, to produce a model of copper-associated cirrhosis in rats. Groups of rat pups suckled on mothers fed 25 mg/kg diet retrorsine were weaned onto a diet containing 0.5 g/kg diet copper and retrorsine in varying dosage for 13 weeks. Histological similarities between the human disease and rats given copper with retrorsine 5 mg/kg diet included parenchymal destruction, fibrosis, nodular regeneration, and copper accumulation. There were significant histological differences from the human disorder, possibly attributable to inter-species variability or the critical timing or duration of exposure to hepatotoxins in the neonatal period. The hypothesis that ICC results from copper and a second hepatotoxin has not been disproved.

Animals↗
PubMed1998

A gene encoding a liver-specific ABC transporter is mutated in progressive familial intrahepatic cholestasis.

The progressive familial intrahepatic cholestases (PFIC) are a group of inherited disorders with severe cholestatic liver disease from early infancy. A subgroup characterized by normal serum cholesterol and gamma-glutamyltranspeptidase (gammaGT) levels is genetically heterogeneous with loci on chromosomes 2q (PFIC2) and 18q. The phenotype of the PFIC2-linked group is consistent with defective bile acid transport at the hepatocyte canalicular membrane. The PFIC2 gene has now been identified by mutations in a positional candidate, BSEP, which encodes a liver-specific ATP-binding cassette (ABC) transporter, sister of p-glycoprotein (SPGP). The product of the orthologous rat gene has been shown to be an effective bile acid transporter in vitro. These data provide evidence that SPGP is the human bile salt export pump (BSEP).

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1998

Role of copper in Indian childhood cirrhosis.

Of the cirrhoses that affect Indian children, Indian childhood cirrhosis (ICC) is a discrete clinical and histologic entity in which large amounts of copper are deposited in the liver. The evidence linking copper deposition to increased dietary copper intake in infancy was reviewed. Prevention of this feeding pattern prevents ICC, and the disease has now largely disappeared from many parts of India. Penicillamine, if given before the terminal clinical stage of ICC, reduces mortality from 92% to 53%. Long-term survivors show a sequence of histologic resolution, resulting either in inactive micronodular cirrhosis or in virtually normal histologic appearance. Twenty-nine treated ICC patients reexamined at 8.8 y of age (range: 6.3-13 y), 5-12 y after diagnosis, were well and had normal results from liver function tests. Clinical and epidemiologic evidence show that there must be excessive copper ingestion for ICC to develop, but the lack of an animal model, the inconstant relation between liver copper concentrations and liver damage, and the rarity of liver disease in adults suggests that other etiologic factors contribute. Two mechanisms are discussed: 1) that copper may be acting in synergy with a hepatotoxin, or 2) that there may be a genetic predisposition to copper-associated liver damage, as suggested recently for Tyrollean childhood cirrhosis. Although ICC is now rare, sporadic cases of an ICC-like disorder in infants continue to occur. There should be a greater awareness among pediatricians of this disease to enable early diagnosis. Penicillamine should be used early and adverse prognostic factors recognized as indications for early transplantation and unregulated water supplies should not be used to prepare infant feeds.

Chelating Agents↗
PubMed1997

Identification of a locus for progressive familial intrahepatic cholestasis PFIC2 on chromosome 2q24.

Progressive familial intrahepatic cholestasis (PFIC; OMIM 211600) is the second most common familial cholestatic syndrome presenting in infancy. A locus has previously been mapped to chromosome 18q21-22 in the original Byler pedigree. This chromosomal region also harbors the locus for benign recurrent intrahepatic cholestasis (BRIC) a related phenotype. Linkage analysis in six consanguineous PFIC pedigrees from the Middle East has previously excluded linkage to chromosome 18q21-22, indicating the existence of locus heterogeneity within the PFIC phenotype. By use of homozygosity mapping and a genome scan in these pedigrees, a locus designated "PFIC2" has been mapped to chromosome 2q24. A maximum LOD score of 8.5 was obtained in the interval between marker loci D2S306 and D2S124, with all families linked.

Cholestasis, Intrahepatic↗
PubMed1996

Long term survival in Indian childhood cirrhosis treated with D-penicillamine.

Indian childhood cirrhosis (ICC) is an almost uniformly fatal disease whose outcome may be modified with penicillamine if given at a sufficiently early stage. Twenty nine children with ICC seen in Pune, India, in 1980-7, who had survived at least five years from onset of penicillamine treatment, were reviewed aged 6.3 to 13 years. They were assessed clinically, biochemically, histologically, and by duplex Doppler ultrasound examination. None had symptoms suggestive of liver disease. There were no toxic effects of penicillamine other than asymptomatic proteinuria. Hepatosplenomegaly reduced significantly and liver function tests returned to normal in all. In four children, significant hepatosplenomegaly was associated with an abnormal duplex Doppler hepatic vein flow pattern and micronodular cirrhosis on biopsy. Clinical findings, growth and development, and ultrasound examination were normal in the remainder. Review of serial liver biopsy specimens showed a sequence of recovery from ICC through inactive micronodular cirrhosis to virtually normal histological appearances. The four children who still have micronodular cirrhosis beyond four years from onset remain on penicillamine treatment. In the others penicillamine was stopped after 1-7 (mean 3.5) years without relapse, strong evidence that ICC is not due to an inborn error of copper metabolism.

Chelating Agents↗
PubMed1996

Locus heterogeneity in progressive familial intrahepatic cholestasis.

Progressive familial intrahepatic cholestasis (PFIC or Byler disease) is a rare autosomal recessive form of severe and fatal cholestatic liver disease. A locus for PFIC has recently been mapped to chromosome 18q21-q22 in the original Byler pedigree. This region harbours the locus for a related phenotype, benign recurrent intrahepatic cholestasis (BRIC), suggesting that these traits are allelic. Linkage analysis was undertaken in five consanguineous PFIC pedigrees from Saudi Arabia using marker loci (D18S69, D18S41, D18S64, D18S38, D18S42, D18S55, D18S68, and D18S61) which span the Byler disease/BRIC region on 18q21-q22. In this family set the disease locus was excluded from this region, showing that locus heterogeneity exists for the PFIC phenotype.

Cholestasis, Intrahepatic↗
PubMed1995

Normal metallothionein synthesis in fibroblasts obtained from children with Indian childhood cirrhosis or copper-associated childhood cirrhosis.

We previously demonstrated decreased metallothionein (MT) synthesis in cultured fibroblasts obtained from an American boy with findings typical of Indian Childhood Cirrhosis (ICC). We now report normal basal, copper-induced, and zinc-induced MT synthesis in the fibroblasts of two Indian boys and one Irish boy with typical ICC and one Indian boy with copper-associated childhood cirrhosis. This suggests that etiologies other than impaired MT production should be sought as the primary defect in these disorders.

Autoradiography↗
PubMed1995

The major histocompatibility complex influences the development of chronic liver disease in male children and young adults with cystic fibrosis.

BACKGROUND/AIMS: Chronic liver disease is a well-recognised complication of cystic fibrosis. Recent reports suggest that its development is not determined by specific mutations within the cystic fibrosis gene; however, familial clustering of portal hypertension cases and inappropriate immune responses against liver membrane antigens demonstrated in children with cystic fibrosis and chronic liver disease suggest that other genetic loci may be relevant. As the major histocompatibility complex has an important immunoregulatory role, we have investigated for associations with this complex and chronic liver disease in cystic fibrosis. METHODS: We have determined human leucocyte antigen class I (A and B) and class II (DR) phenotypes by serological tissue typing and class II (DR and DQ) and class III (complement component C4 and 21-hydroxylase) gene polymorphisms in 274 children and young adults with cystic fibrosis, of whom 82 had evidence of chronic liver disease with portal hypertension in 49, and 146 healthy controls. RESULTS: A marked difference in human leucocyte antigen frequency was limited to DQ6, which was found in 66.7% of cystic fibrosis patients with liver disease compared to 32.9% of patients with no liver disease (Pc < 0.03) and 28.8% of controls (Pc < 0.006). An increased frequency of the two antigens in strong linkage disequilibrium with DQ6 was also observed within this patient group, namely DR15 and B7. When the patients were stratified for the presence of portal hypertension, these observations were confirmed, but the human leucocyte antigen associations were significant only for male patients and there was no association with the age of onset of liver disease. CONCLUSIONS: These data suggest that the haplotype B7-DR15-DQ6 may carry an increased risk of development of liver disease in male cystic fibrosis patients.

Adolescent↗
PubMed1995

Reversal of Indian childhood cirrhosis by D-penicillamine therapy.

Serial liver biopsy changes have been reviewed in 30 patients with Indian childhood cirrhosis (ICC) who were randomly allocated to receive treatment with penicillamine in a dose of 20 mg/kg/day, 10 of whom also received prednisolone, and five receiving placebo. The latter died within 185 (mean, 149) days of starting treatment. Nine receiving penicillamine died within 540 (mean, 338) days, but the remainder are well 5.1-9.3 years after commencing treatment. Initial biopsies showed severe hepatocellular injury, pericellular fibrosis, inflammatory infiltration, and orcein-staining granules. Second biopsies taken within 6 months of starting penicillamine usually showed persistence of inflammation and an increase in nodularity with thick and thin active septae. Subsequently the appearances were of an inactive micronodular cirrhosis, with reduction in septal inflammatory infiltrate, hepatocellular injury, and intensity of orcein staining. This further improved to a stage of incomplete fibrous septae. The last liver biopsies at 6-60 months (in 21 survivors) showed almost normal histology in four, incomplete fibrous septae in five, and inactive micronodular cirrhosis with thin septae in 12. Mean liver copper concentrations decreased from 1,407 (SEM, 121) micrograms/g at presentation to 925 (183), 317 (100), and 127 (35) at 6, 6-18, and > 18 months after starting treatment. By contrast, a second biopsy taken in the 6 months after diagnosis in placebo-treated children showed persistence of ICC with increase in inflammation, fibrosis, and orcein staining.

Biopsy↗
PubMed1994

Copper associated childhood cirrhosis.

Several papers have reported severe liver disease in association with massive hepatic copper accumulation, which do not seem to be either of the recognised copper associated liver diseases, namely Wilson's disease and Indian childhood cirrhosis. A further case is reported in which novel copper kinetic studies were carried out using the stable isotope 65Cu, showing that this patient did not suffer from Wilson's disease. It is suggested that these cases can be divided into two groups on the basis of age, clinical course, and history of excessive copper ingestion. The benefits of using 65Cu for in vivo studies of copper metabolism is discussed.

Bangladesh↗
PubMed1994

Development of a PCR probe test for identifying Pseudomonas aeruginosa and Pseudomonas (Burkholderia) cepacia.

AIMS: To develop a system of species specific polymerase chain reaction (PCR) and DNA hybridisation based on 16s ribosomal RNA sequences for the identification of Pseudomonas aeruginosa and Pseudomonas (Burkholderia) cepacia in sputum from children with cystic fibrosis. METHODS: Most of the 16s rRNA sequences from strains of Ps aeruginosa, Ps (Burkholderia) cepacia, and Ps putida were determined. PCR primers and DNA probes were synthesised from suitable sequences and then evaluated on bacterial cultures and sputum samples. RESULTS: About 1000 bases of sequence was obtained from strains of Ps aeruginosa, Ps (Burkholderia) cepacia, and Ps putida. PCR of bacterial cultures was species specific, but PCR on sputum resulted in some non-specific amplification products. The subsequent hybridisation reaction was species specific. CONCLUSION: A species specific system of PCR and DNA hybridisation based on 16s rRNA sequences is applicable in clinical practice, and may aid the early diagnosis of respiratory tract infection with small numbers of Ps aeruginosa and Ps (Burkholderia) cepacia in patients with cystic fibrosis.

Base Sequence↗
PubMed1994

Liver histology in the arthrogryposis multiplex congenita, renal dysfunction, and cholestasis (ARC) syndrome: report of three new cases and review.

We report three cases from two unrelated families of infants with arthrogryposis multiplex congenita, cholestatic jaundice, and renal Fanconi's syndrome. In both families the parents were consanguineous. All three children died by 7 months of age. This association was first reported in 1973 by Lutz-Richner and Landolt and again in another family by Nezelof et al in 1979. However, because of differing liver histology the two sibships were considered to have two separate conditions. Based on the histological findings in one of our cases we propose that all cases described so far represent variation within a single syndrome.

Abnormalities, Multiple↗