Byler disease (ByD) is an autosomal recessive disorder in which cholestasis of onset in infancy leads to hepatic fibrosis and death. Children who have a clinically similar disorder, but are not members of the Amish kindred in which ByD was described, are said to have Byler syndrome (ByS). Controversy exists as to whether ByD and ByS (subtypes of progressive familial intrahepatic cholestasis [PFIC]) represent one clinicopathological entity. The gene for ByD has been mapped to a 19-cM region of 18q21-q22. PFIC caused by a lesion in this region, including ByD, can be designated PFIC-1. Examination of haplotypes in siblings with ByS in two unrelated non-Amish families showed that the gene(s) responsible for their disorder(s) did not lie in the PFIC-1 candidate region. On light microscopy and transmission electron microscopy (TEM), liver tissue differed between Amish children with PFIC-1, who had coarsely granular bile and at presentation had bland intracanalicular cholestasis, and the children with ByS in the two non-Amish families, who had amorphous or finely filamentous bile and at presentation had neonatal hepatitis. Bile acid composition of bile also differed: In the Amish children with PFIC-1 and in one ByS family, the proportional concentration of chenodeoxycholic acid (CDCA) in bile was low compared with normal bile; in the other ByS family, it was only slightly reduced. Genetic analysis and light microscopy and TEM of liver may help distinguish PFIC-1 from other forms of ByS.

Two groups (Tazawa Y etal., J Pediatr Gastroenterol Nutr 1985;4:32; Jacquemin E etal., Eur J Pediatr 1994;153:424) have reported that bile of children with Byler syndrome is deficient in chenodeoxycholic acid (CDCA). Byler syndrome, however, is clinically defined and may be heterogeneous, embracing several forms of progressive familial intrahepatic cholestasis (PFIC). The gene for Byler disease has recently been mapped to 18q21-q22, using materials from members of the eponymous Amish kindred (Carlton VEH etal., Hum Mol Genet 1995;4:1049). Gallbladder bile from one Amish child with Byler disease and duodenal fluid from another were analyzed by gas chromatography - mass spectroscopy; the relative proportion of CDCA in both was markedly low. The children were homozygously identical by descent at the Byler disease locus, as demonstrated by comparison of microsatellite haplotypes (CMH). Gallbladder bile from a non-Amish child with Byler syndrome, receiving ursodeoxycholic acid (UDCA), and duodenal fluid from her brother with Byler syndrome, not receiving UDCA, were similarly analyzed. The relative proportion of CDCA in the duodenal fluid was markedly low; that in the gallbladder bile was subnormal, but was three times higher than that in the duodenal fluid. CMH at the Byler disease locus demonstrated differences between the siblings, indicating that the gene responsible for Byler syndrome in this kindred lies elsewhere. Both the gene responsible for Byler disease and that responsible for Byler syndrome in the non-Amish children seem to affect biliary levels of CDCA. Increased biliary CDCA during UDCA administration may point to a defect in synthesis, rather than in canalicular secretion, of CDCA. Bile acid composition of gallbladder bile or duodenal fluid must be interpreted in conjunction with other data to distinguish among forms of PFIC classed as Byler syndrome.

We studied the acinar distribution for uptake of the bile acid analogue [125I]-cholylglycyltyrosine in livers from adult and 14-day-old suckling rats. Portal and peripheral (systemic) serum bile acid concentrations were also measured by combined gas chromatography-mass spectrometry as an independent index of hepatic bile acid clearance from portal blood. Utilizing light microscopic autoradiography, a steep, decreasing portal to centrilobular gradient for cholylglycyltyrosine uptake was noted in adult rat liver. In contrast, there was no lobular gradient for cholylglycyltyrosine uptake visible in the 14-day-rat liver; all hepatocytes within the acinus contained a similar number of silver grains. Portal vein total bile acid concentrations were significantly higher in serum of adult compared to 14-day-old rats. In contrast, bile acid concentrations were 10-fold higher in the peripheral serum of developing versus adult rats. The peripheral to portal serum bile acid concentration ratio was 0.23 in the adult and 6.48 in the 14-day-old rat. We conclude that the entire hepatic lobule participates in the uptake of bile acids in the 14-day-old rat even under the basal conditions of this study. The normal "reserve" function of centrilobular hepatocytes is not sufficient to compensate for the decreased transport capacity of the developing liver with the result that increased concentrations of bile acids enter and accumulate in the systemic circulation.

Previous studies of the bile acid composition of meconium and bile obtained in the first few days of life indicate that, compared to the adult, there are significant differences in the hepatic synthesis of bile acids. Analysis of human fetal gallbladder bile provides a more direct assessment of primary hepatic synthesis in utero, but only limited studies have been described. Using HPLC, GLC and mass speetrometry the bile acid composition was determined for fetal gallbladder bile obtained after legal abortion between the 14th and 20th weeks of gestation. Chenodeoxycholic and cholic acids were the major bile acids identified however the profiles were characterized by an array of metabolites not normally found in adult bile. Hyocholic acid levels often exceeded those of cholic acid indicating C-6 hydroxylation to be a major pathway for bile acid synthesis in early life. Bile acid concentrations were relatively low before week 17 of gestation but showed a significant surge thereafter, increasing by >10 fold by week 20. The ratio of chenodeoxycholic:cholic acid in bile was constant (0.85) over this period and much lower than for newborn bile and adult bile indicating an immaturity in hepatic 12α-hydroxylase in early development. These observations demonstrate that more than 50% of the bile acids are accounted for by atypical bile acids and that the profile resembles that found in adults with cholestasis. This may in part account for the physiologic cholestasis of the newborn.

The continued use over many years of mass spectrometry (MS) for bile acid analysis can be attributed to its value as a method for providing definitive qualitative and quantitative information. Its combination with gas chromatography (GC—MS) has been particularly important for investigating the stereochemical variety of the structure of bile acids in relation to their biosynthesis, transport, and metabolism.

1. Pruritus was assessed in 19 patients by measurement of nocturnal limb movement. 2. Serum (nine pruritic, ten non-pruritic) and interstitial fluid (five pruritic, three non-pruritic) bile acids were fractionated according to their mode of conjugation by using DEAP-Sephadex LH-20 and measured by gas chromatography-mass spectrometry. 3. No correlation was found between serum or interstitial fluid total bile acid or individual bile acid concentrations and pruritus. Bile acid profiles in the two groups of patients were similar and there was no correlation between pruritus and the conjugation pattern. 4. Te bile acid profile of interstitial fluid reflected that of serum and a linear relationship was found between serum and interstitial fluid bile acid concentrations (r ;.95, P less than 0.001). 5. The proportion of bile acid sulphate in interstitial fluid was significantly smaller than that in serum (P less than 0.025), where sulphates accounted for up to 46% of the total bile acids. 6. In three patients, a decrease in serum bile acid concentrations achieved by percutaneous transhepatic biliary drainage had little or no effect on pruritus. 7. These findings suggest that bile acids do not have a causative role in the pruritus of cholestatic liver disease.

The range of serum cholesterol in the healthy population has been determined for male and female subjects in ten year age groups.

A rapid method is described for the detection and quantitation of amphetamine in urine using gas-liquid chromatography. The technique incorporates the use of an internal standard diphenylamine. The method is sensitive to 1.0 μg per 100 ml of amphetamine in urine. Confirmation of the specificity of each measurement is obtained by comparison of the relative retention time of the “amphetamine” against an internal standard and the preparation of a ketone derivative.

The method described by Watson for estimation of serum cholesterol has been reinvestigated and an improved procedure suggested.