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Biomedical subjects

J R Bloomer

Publications and source records attributed to J R Bloomer.

16 recordsLinked to original sources
PubMed1979

Enzymatic fluorometry for estimating serum total bile acid concentration.

Fasting serum total bile acid (SBA) levels were estimated by enzymatic fluorometry (EF) in 36 subjects without liver disease, 28 with hepatic lesions and impaired hepatic function, and 79 with hepatic lesions and normal function. Fasting and postprandial EF-SBA levels were compared in nine normal subjects and nine patients with cholestasis, and SBA assays by EF and gas-liquid chromatography (GLC) were compared in 28 patients with hepatic lesions and impaired function. Levels of SBA were below 9 mumole/L in all but two of the 36 subjects without liver disease, and above that level in all 28 with impaired hepatic function and 17 (24%) of the 70 with hepatic lesions and normal liver function. In most subjects, EF detected notable postprandial rises in SBA. Enzymatic fluorometric and GLC-SBA values were closely correlated (coefficient of correlation, 0.869).

3-Hydroxysteroid Dehydrogenases↗
PubMed1979

Effect of endogenous heme generation on delta-aminolevulinic acid synthase activity in rat liver mitochondria.

This study examined the possibility that generation of heme within mitochondria may provide a local concentration sufficient to inhibit the activity of delta-aminolevulinic acid (ALA) synthase, the enzyme that catalyzes the rate-limiting step in hepatic heme biosynthesis. This was accomplished by simultaneously running ALA synthase and heme synthase activities in intact mitochondria isolated from rat liver. Radiochemical assays were used to measure the enzyme activities. ALA synthase activity did not decrease as the rate of heme formation was increased by varying the concentration of substrates for heme synthase. Even at a rate of heme generation estimated to be at least 75 times the rate occuring in vivo, ALA synthase activity was unchanged. We conclude that end product inhibition of ALA synthase activity by heme is not an important physiological mechanism for regulation of hepatic heme biosynthesis.

5-Aminolevulinate Synthetase↗
PubMed1978

Efficacy and safety of long-term phenobarbital therapy of familial cholestasis.

Two brothers with progressive familial intrahepatic cholestasis were followed during four years of phenobarbital therapy to assess its long-term safety and efficacy. Effects attributable to phenobarbital included sustained relief of pruritus, lowering of serum bilirubin levels, and enhanced hepatic excretion of 131I-rose bengal; serum bile acid levels were only transiently decreased. Two brief interruptions in therapy resulted in symptomatic deterioration. Phenobarbital did not retard growth nor impede the response to vitamin D therapy of concomitant rickets.

Bile Acids and Salts↗
PubMed1977

Heme content of normal and porphyric cultured skin fibroblasts.

Partial deficiencies in enzyme activities of the heme biosynthetic pathway have been demonstrated in cultured skin fibroblasts and other tissues from patients with protoporphyria (PP) and acute intermittent porphyria (AIP). We have quantitatively and qualitatively assessed the heme and free porphyrin content in cultured PP, AIP, VP (variegate porphyria, in which an enzymatic deficiency has not been identified), and normal skin fibroblasts during routine culture conditions in order to assess the overall metabolism of heme in these cells. The total heme concentration was not significantly different between control and porphyric lines; 189 +/- 15 pmoles/mg protein (mean +/- SEM) in controls, 154 +/- 17 in PP, 175 +/- 20 in AIP, and 181 +/- 81 in VP. The hemoprotein difference spectra were similar in all lines. Free porphyrins were not detected in any of the disorders. Despite partial deficiencies in enzyme activities of the heme pathway, porphyric fibroblasts thus maintain normal heme content during routine culture conditions without detectable porphyrin accumulation.

Cells, Cultured↗
PubMed1977

Study of factors causing excess protoporphyrin accumulation in cultured skin fibroblasts from patients with protoporphyria.

The activity of heme synthetase, which catalyzes the chelation of ferrous iron to protoporphyrin to form heme, is deficient in sonicates of skin fibroblasts cultured from patients with protoporphyria. During culture in Eagle's medium supplemented with fetal calf serum, these cells do not accumulate protoporphyrin, however. This may be due to a minimal requirement for heme synthesis, since glycine is incorporated into heme at a low rate which is similar to that in normal fibroblasts. In addition, the activity of delta-aminolevulinic acid (ALA) synthetase, the first and rate-limiting enzyme of heme biosynthesis which catalyzes the formation of ALA from glycine, is normal in lysates of the fibroblasts. Cultured fibroblasts were therefore incubated with ALA in order to bypass the rate-limiting step of heme biosynthesis. In the presence of 25 muM iron, protoporphyrin was detected in protoporphyria cell lines when the concentration of ALA in the medium reached 50 muM, but not in normal lines. As the concentration of ALA was increased above 50 muM, all lines accumulated protoporphyrin. However, the amount was 2-3 times more in cultured fibroblasts from patients with protoporphyria, reflecting their deficiency of heme synthetase activity. When iron was not added to the medium, protoporphyrin accumulated to a similar degree in normal and protoporphyria fibroblasts; this was significantly more than that in the presence of iron. These studies indicate that excessive protoporphyrin accumulation in protoporphyria, which is due principally to deficient heme synthetase activity, may be modified by the rate of ALA formation in heme-producing tissues, and by the availability of iron.

Carbon Radioisotopes↗
PubMed1977

Serum alpha-fetoprotein in patients with massive hepatic necrosis.

Serum concentrations of alpha-fetoprotein (AFP) were measured by radioimmunoassay in 12 patients with massive hepatic necrosis, 11 of whom died. Levels were significantly elevated after the 8th day of illness in 8 of the 9 patients who died between the 10th and 60th day, and in the 1 patient who survived. All 9 patients with increased levels of serum AFP exhibited histological evidence of hepatic regeneration. These findings indicate that the rise in serum AFP in massive hepatic necrosis is related to the duration of survival after the onset of illness, but does not necessarily imply ultimate recovery. Because available evidence suggests that the serum AFP level reflects hepatic regenerative activity, it appears that the onset of regeneration in fulminant hepatitis is delayed until the 2nd week of illness.

Adolescent↗
PubMed1977

Elevations in skin tissue levels of bile acids in human cholestasis: relation to serum levels and topruritus.

To define the relationship of bile acid retention to the pruritus of cholestasis, we quantified individual bile acids in serum, acetone swabs of skin, and skin tissue in 13 patients with cholestasis undergoing laparotomy and in 8 controls. There was no consistent relationship between pruritus and concentrations of either total or individual bile acids in serum. Skin tissue concentrations of bile acids were elevated in patients with cholestasis, were linearly related to serum levels, and did not differentiate between those patients with and those without pruritus. Concentrations of bile acids on the skin surface, which were lower than those reported by others, did not correlate with pruritus, and were decreased by simple soap and water washing. These data indicate that the pruritus of cholestasis is not directly related to the skin tissue concentration of any of the major bile acids, although a relationship to a particular molecular form of bile acids could not be excluded.

Adult↗
PubMed1976

Inheritance in protoporphyria. Comparison of haem synthetase activity in skin fibroblasts with clinical features.

The activity of haem synthetase, the enzyme which chelates iron to protoporphyrin to form haem, was measured in cultured skin fibroblasts of children with protoporphyria and their parents from three families. In each family, one parent had deficient haem synthetase activity (3-0-11-1 pmol protohaem formed/mg protein/h) when compared to values in eight non-porphyric controls (means 24-9, range 13-7-51-5). The level of activity in the three parents was similar to that in their affected children. In two families the parent with deficient activity was also thought to be the carrier of the abnormal gene, as judged from a history of photosensitivity and analysis of erythrocyte protoporphyrin concentrations, but in the third family the pattern of inheritance could not be determined from these criteria. The activity of delta-aminolaevulinic acid synthetase was normal in cultured fibroblasts from the protoporphyric children and their parents, excluding a generalised defect in haem-pathway enzymes. These results support the premise that deficient haem synthetase activity, inherited in an autosomal dominant patter, is the primary defect in protoporphyria.

Adolescent↗
PubMed1975

alpha-fetoprotein in noneoplastic hepatic disorders.

Serum alpha-fetoprotein levels were measured by radioimmunoassay in 473 patients with biopsy-proved noneoplastic hepatic disorders; 22% had values greater than 40 ng/ml, whereas only 1 of 350 patients with nonhepatic benign diseases had a value greater than this. Levels exceeded 40 ng/ml in more than 30% of patients with various types of hepatitis, and in 0% to 15% with inactive postnecrotic cirrhosis, primary biliary cirrhosis, biliary tract obstruction, and alcoholic liver disease. Values greater than 500 mg/ml were observed solely in viral subacute hepatic necrois. Only one patient had a level exceeding 3,000 ng/ml, the concentration at which alpha-fetoprotein is detectable by agar-gel diffusion. Of 75 patients with hepatoma, serum alpha-fetoprotein levels exceeded 40 ng/ml in 69%, and exceeded 3,000 ng/ml in 48%. These studies indicate that serum alpha-fetoprotein levels are elevated in several nonneoplastic hepatic disorders when a sensitive assay is used; this phenomenon may reflect hepatic regeneration.

Acute Disease↗
PubMed1975

Relationship of serum alpha-fetoprotein to the severity and duration of illness in patients with viral hepatitis.

Using a radioimmunoassay which detect concentrations of alpha-fetoprotein as low as 5 ng per ml, 38% of 176 patients with viral hepatitis compared with health volunteers and patients with chronic diseases not affecting the liver. When separated into two groups based on histological classification of liver biopsy specimens, differences in the degree and frequency of increased serum alpha-fetoprotein were related to the severity of the hepatic lesion. Of 75 patients with the lesion of viral subacute hepatic necrosis, in which zones of necrosis bridge adjacent portal triads or central veins, 52% had increased values, and 12% had levels ranging from 500 to 3300 ng per ml. In contrast, only 28% of the 101 patients without bridging necrosis had increased values, and none had levels that exceeded 500 ng per ml. In the patients with subacute hepatic necrosis, comparison of alpha-fetoprotein concentrations with the duration of illness indicated that the protein rose to peak levels in serum as the SGOT was declining. This was confirmed by serial observations in 10 patients. Thus, the increase of alpha-fetoprotein in the sera of patients with severe hepatitis occurs as liver necrosis is subsiding. Due to other known features of alpha-fetoprotein, it is intriguing to speculate that the increase in serum levels of this protein in viral hepatitis reflects hepatic regeneration after parenchymal damage.

Adult↗
PubMedDate not supplied

Comparison of human and bovine protoporphyria.

Protoporphyria (PP) is an inherited disorder of porphyrin metabolism in man in which there is excessive accumulation and excretion of protoporphyrin. Recently, a similar disorder has been described in cattle. In this report, the clinical, biochemical, and genetic features of bovine and human PP are compared. Human and bovine PP are characterized by photosensitivity and elevation of erythrocyte and fecal protoporphyrin levels. In both disorders, a deficiency of heme synthase activity is present in all tissues which have been examined. The diseases differ clinically in that hepatobiliary disease has been found thus far only in human PP. They also have different inheritance patterns. Human PP is an autosomal dominant disease, while initial studies strongly suggest that there is an autosomal recessive pattern of inheritance in bovine PP.

Animals↗
PubMedDate not supplied

Chronic hepatitis associated with drug abuse: significance of hepatitis B virus.

One hundred and seventy-seven former heroin addicts, consisting of 85 who were newly admitted to a methadone maintenance program and 92 who had received methadone for a mean period of 30 months, were prospectively studied for up to 2 years in order to determine: (1) the effect of heroin withdrawal on the hepatic abnormalities, and (2) the incidence of HBsAg, anti-HBs, and anti-HCc as indices of the frequency of hepatitis B virus infection. Our study indicates that (1) hepatic abnormalities persist when heroin is discontinued and are not temporally related to drug and/or needle usage, and (2) that 71% of subjects had either HBsAg or anti-HBs; anti-HBc was tested for in 16 patients and was present in 100%, although 9 of the 16 were both HBsAg- and anti-HBs-negative. This study suggests that hepatitis B is largely responsible for the liver dysfunction. It is proposed that an abnormality in immune function, induced by heroin, is responsible for the high incidence of chronic hepatitis. Attention is drawn to the similarity between former drug addicts and hemophiliacs, since both develop chronic hepatitis in spite of anti-HBs in the serum.

Adult↗
PubMedDate not supplied

Pathogenesis and therapy of liver disease in protoporphyria.

Protoporphyria is an inherited disorder in man characterized by the overproduction of protoporphyrin, a compound that is excreted by the liver. Hepatobiliary disease may occur in protoporphyria, and several cases have been reported in which death was due to liver disease. Based on the histological evaluation of liver biopsy specimens from 18 patients, 6 of whom died with cirrhosis and liver failure, we speculate that liver disease in this condition is caused by protoporphyrin deposits in hepatobiliary structures. These deposits are composed of crystals and have a characteristic birefringence when examined by polarization microscopy.One patient with early liver damage was given cholestyramine and vitamin E in an attempt to reduce the amount of protoporphyrin which the liver excreted daily. Liver function tests returned to normal, and red cell and plasma protoporphyrin levels decreased. A repeat liver biopsy after one year of therapy showed healing, with decrease of the protoporphyrin deposits.Liver disease in protoporphyria may be treated by directing therapy toward the metabolic abnormality.

5-Aminolevulinate Synthetase↗
PubMedDate not supplied

Itch in liver disease: facts and speculations.

Pruritus in hepatobiliary disease is commonly believed to be caused by retention of bile acids with their sequestration in the skin. HOwever, we have recently demonstrated that skin levels of bile acids in patients with cholestasis correlate poorly with pruritus. In this report, we present additional data concerning the relationship of pruritus to bile acid retention: (1) the urinary excretion of sulfated and nonsulfated bile acids was not significantly different in patients with cholestasis who itched compared to those who did not; (2) one patient with itch associated with a liver abscess had normal levels of bile acids in serum, skin, and urine; (3) patients with primary biliary cirrhosis who itched had lower serum bile acid levels than patients with mechanical biliary obstruction who did not itch.These studies support our premise that pruritus in hepatobiliary diseases is not directly related to bile acid retention. They suggest that the type of cholestatic disorder, and not simply the magnitude of the cholestasis, as estimated by the elevation of serum bile acids, is important. We propose that the agent responsible for pruritus is produced in response to cholestasis, possibly through activation of the alternate pathway of bile acid synthesis. Properties of the hypothetical pruritogen are discussed.

Adult↗