From heroic treatment to futile therapy: end-of-life ethics for the coming millennium.
Explore the source record for details and available documents.
Ethics, Medical↗
Biomedical subjects
M M Thaler
Publications and source records attributed to M M Thaler.
Hepatitis C virus in infants and children.
Hepatitis C virus (HCV) affects approximately 1% of the world's people. In the past there has been a lack of interest in HCV in the pediatric population; however, new data are accumulating at an exponential pace about the epidemiology, clinical spectrum, HCV genotypes, and molecular variants and evolution of HCV infection in infants and children. Thousands of children with chronic hepatitis C are enrolled in multicenter and multinational clinical protocols and therapeutic trials. This paper highlights recent advances in diagnosis, epidemiology, natural history, and therapy for hepatitis C in children and the implications of these advances for pediatric and primary care practice.
Child↗
Bile pigment composition and bilirubin esterification in the developing chick.
In vivo and in vitro bile pigment metabolism was studied in embryos, chicks, and mature White Leghorn hens. Biliverdin and bilirubin pigments were present in bile of embryos from the earliest stage examined (14 d). Bilirubin accounted for 2.5-11.5% of total bile pigments, with the higher percentages in the early embryo. Biliverdin was exclusively in unesterified form. In contrast, bilirubin was almost entirely (> 98%) in esterified form. Glucosides consistently predominated over glucuronides and xylosides (6:3:1). In serum, bilirubin and biliverdin were undetectable at all embryonic stages and after hatching. Bilirubin UDP-glycosyltransferase activities with UDP-glucuronic acid, UDP-glucose, and UDP-xylose were detectable in chick embryo liver and averaged 67, 72, and 102%, respectively, of the corresponding adult mean values, without significant change throughout development. We conclude that multiple bilirubin esterification systems mature early in the avian embryo. This is in marked contrast to the development of bilirubin metabolism in the mammalian fetus in which detoxication of this potentially toxic pigment is achieved by placental clearance, and bilirubin esterification matures only after delivery. These contrasting developmental patterns are consistent with an adaptive response to the different requirements in the avian embryo and mammalian fetus for self-protective detoxification of unconjugated bilirubin.
Animals↗
Hepatitis C in HIV-infected patients with and without AIDS: prevalence and relationship to patient survival.
BACKGROUND: Limited information is available about the prevalence of hepatitis C virus in patients with human immunodeficiency virus in relation to specific risk factors or about the influence of hepatitis C virus coinfection on survival. This retrospective study addressed these questions. METHODS: The study population consisted of 512 predominantly non-intravenous drug-using male homosexuals, 224 of whom had AIDS. Samples positive for hepatitis C virus antibody by second-generation enzyme immunoassay were further tested by means of strip immunoblot assay, and for hepatitis C virus RNA by means of polymerase chain reaction amplification. A randomly selected set of enzyme immunoassay-negative samples was also tested for hepatitis C virus RNA and, if hepatitis C virus RNA positive, by a second-generation recombinant immunoblot assay. RESULTS: The prevalence of hepatitis C virus infection unaccounted for by intravenous drug use or transfusion was 11.7% by enzyme immunoassay, and 87% of sera positive by enzyme immunoassay were also positive by second-generation recombinant immunoblot assay or hepatitis C virus RNA analysis. Hepatitis C virus RNA was detectable in 53% of enzyme immunoassay-positive samples but in only about 1% of enzyme immunoassay-negative samples. Hepatitis C virus coinfection did not influence survival of HIV-infected patients with or without manifestations of AIDS. CONCLUSIONS: Hepatitis C virus infection in nontransfused, non-intravenous drug-using patients with HIV infection is several times more prevalent than in volunteer blood donors, suggesting homosexual transmission of hepatitis C virus. About half of patients seropositive for hepatitis C virus antibody have detectable hepatitis C virus RNA, and serologically occult hepatitis C virus viremia is rare. Hepatitis C virus coinfection does not appear to adversely influence survival.
Acquired Immunodeficiency Syndrome↗
A unique, predominant hepatitis C virus variant found in an infant born to a mother with multiple variants.
To demonstrate vertical transmission of hepatitis C virus (HCV) from an HCV-infected, non-human immunodeficiency virus type 1-infected mother to her infant and to assess the distribution of viral species in the mother and infant, the hypervariable region of the gene encoding the putative envelope glycoprotein E2 (E2HV) was sequenced in three mothers and one mother-infant pair. The data indicate that (i) quasi-species distributions of HCV E2HV variants were found in all four mothers, (ii) a single predominant HCV E2HV variant was found in the infant of a mother shown to have nine predominant E2HV variants, and (iii) the infant's E2HV variant was highly related to, but not identical with, the nine variants identified in the mother at the time of birth. These findings indicate that HCV is transmitted from mother to infant and raise the possibility that the transmission occurs in utero.
Amino Acid Sequence↗
Hepatitis B in patients with HIV infection: relationship to AIDS and patient survival.
Explore the source record for details and available documents.
AIDS-Related Opportunistic Infections↗
Failure of expression of the phenobarbital-induced enhancement of UDP-glycosyltransferases in native, sealed endoplasmic reticulum vesicles from rat liver.
Conflicting data have been published regarding the effects of phenobarbital treatment on bilirubin UDP-glucuronyltransferase activity in native liver microsomes. Recent evidence suggests that the bilirubin UDP-glycosyltransferase system faces the interior of microsomal vesicles, and that expression of its activities in sealed microsomes may be rate-limited by transport of UDP sugars across the membrane. These observations raise the possibility that the reported variability in the effects of phenobarbital may reflect differences in integrity of the membrane in microsomal preparations. We examined the effect of phenobarbital on bilirubin UDP-glucosyltransferase and the UDP-glucuronyltransferase activities towards bilirubin, 4-nitrophenol, and 1-naphthol using native rat liver microsomes with verified vesicle integrity. Phenobarbital-induced microsomes in which the membrane permeability barrier was eliminated by pretreatment with detergent displayed markedly higher UDP-glycosyltransferase activities towards all tested substrates compared with activities in similarly disrupted microsomes from untreated rats. In contrast, none of the transferase activities tested were significantly enhanced by phenobarbital treatment when the enzymic activities were assayed in sealed microsomes. Addition to the enzyme assay mixture of UDPGlcNAc, a presumed physiological activator of the UDP-glucuronyltransferases, failed to expose the enhanced UDP-glucuronyltransferase concentration in phenobarbital-induced sealed microsomes. Our findings are consistent with the idea that transport of UDP sugar across the membrane may be rate-limiting for expression of UDP-glycosyltransferase activities in sealed microsomes. Quantitative assessment of membrane integrity is an essential prerequisite in experiments designed to study the regulation of the microsomal UDP-glycosyltransferase system.
Animals↗
Vertical transmission of hepatitis C virus.
There is evidence that hepatitis C virus (HCV) may be vertically transmitted from infected mothers to their children. To test this hypothesis, we prospectively studied 10 pregnant women at high risk from parenterally or sexually transmitted diseases with the polymerase chain reaction. HCV RNA was found in 8 newborn babies delivered by women who were anti-HCV seropositive, and persisted for 2-19 months of follow-up. Anti-HCV detected in 7 infants cleared by 9 months and remained undetectable thereafter. Serum alanine aminotransferase was raised in 3 infants. The findings provide evidence of vertical transmission of HCV and suggest that perinatal infection may initiate a silent disease process or chronic carrier state.
Alanine Transaminase↗
Hepatitis C virus infection in infants whose mothers took street drugs intravenously.
To assess the risk of transmission of hepatitis C virus from mother to infant during pregnancy or at delivery, we measured the antibody to hepatitis C virus (anti-HCV) by an enzyme-linked immunosorbent assay (ELISA) and a recombinant immunoblot assay (RIBA) in serum from 43 infants whose mothers took illicit drugs intravenously. Passively transmitted maternal anti-HCV was detected in 17 (40%) of the 43 infants tested with the ELISA during the first 4 postnatal months. Ten of these initially seropositive infants were followed to 15 months of age or beyond; anti-HCV cleared from nine infants and persisted in one. Among 24 initially seronegative infants, three (12.5%) showed persistent anti-HCV at 6, 11, and 18 months of age, respectively. The remaining two infants were initially tested with ELISA at 6 and 15 months of age; both were transiently seropositive, but anti-HCV disappeared by 12 and 24 months of age, respectively. Among the 17 infants with maternal antibody, nine with ELISA reactions greater than 2.5 optical density units were reactive by RIBA: the eight with weaker reactivity by ELISA were nonreactive by RIBA. When serum samples from the four infants who showed persistent reactivity by ELISA were tested with RIBA, one reacted to both antigens displayed by RIBA (C-100 and 5-1-1), one reacted to the 5-1-1 antigen only, and two were nonreactive. Serum transaminase values were elevated in three of these four infants; all four were also infected with human immunodeficiency virus. The results indicate that vertically transmitted hepatitis C virus may be a cause of hepatitis in infants, especially those coinfected with human immunodeficiency virus. Neonates at risk of hepatitis C virus infection should be monitored beyond 12 months of age. The interpretation of tests for anti-HCV antibody during infancy requires further investigation.
Child, Preschool↗
Hepatic copper metabolism in a mouse model for Menkes' kinky hair syndrome.
Menkes' kinky hair syndrome (KHS) is a lethal x-linked neurodegenerative disorder of copper metabolism, with low serum copper concentrations, tissue-specific copper sequestration, and decreased activities of cuproenzymes in a number of cell types. Although liver copper accumulation is abnormal in KHS, the actual defect in hepatic copper metabolism has not been elucidated. Our studies of liver copper metabolism were conducted in the mottled (blotchy) mouse, an animal model of KHS. After implantation of central venous and biliary catheters in both blotchy and control mice, we measured biliary copper excretion, hepatic copper uptake, and tissue copper contents over an 8-h period after i.v. bolus administration of radioactive 64Cu. Under the experimental conditions used, bile flow and biliary bile acid excretion were held constant, and control and blotchy hepatic 64Cu concentrations were similar in the face of the expected differential in control and mutant kidney 64Cu contents. Biliary excretion of radiocopper was 24.7 +/- 1.5% of injected 64Cu over 8 h in control animals, whereas heterozygotes excreted 6.5 +/- 1.3% and a single hemizygote excreted less than 2%. The pattern of biliary copper excretion was different, with sharp increase and steady decline in control biliary 64Cu excretion but consistently low excretion in mutant mice. No differences were observed in control or mutant hepatic uptake of 64Cu. These data show a reduced biliary excretion of copper in the blotchy mouse, in the absence of a defect in hepatic copper uptake. We suggest that defective copper transport from hepatocyte to bile represents the hepatic expression of the mottled mutation and speculate that a similar defect occurs in human KHS.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Sexual differentiation of rat hepatic bile salt sulfotransferase isoenzymes.
The mature female rat has three times the hepatic bile salt sulfotransferase (BSS) activity compared with male rats. This study examined the changes in two hepatic BSS isoenzyme activities during sexual maturation, and the role of estrogen in development of sex differences in BSS activities in mature rats. DEAE-Sephadex A-50 chromatography of hepatic cytosol from prepubescent pups revealed that more than 90% of total BSS activity was due to BSS I activity relative to BSS II, similar to postpubertal females. Sex differences in total BSS activities and the isoenzyme patterns developed after the onset of puberty at 30-35 days of age. BSS I was still the predominant isoenzyme in the adolescent female, similar to the prepubescent pup and mature female. In contrast, BSS I activity declined in adolescent males, which appeared to explain the fall in total BSS activity to only one-third of that of the female by maturity. BSS II activity was similar in both sexes at any age. Estrogen treatment of postpubertal male rats rapidly increased hepatic BSS capacity by enhancing BSS I activity producing an isoenzyme pattern similar to the mature female. This rapid enhancement of BSS I by estrogen was blocked by actinomycin D and puromycin. We concluded that 1) sex differences in BSS activities that develop during adolescence were in part due estrogen-maintaining BSS I activity in females and 2) estrogen regulates the synthesis of BSS I at a translational (or pretranslational) level.
Animals↗
Auxiliary transplantation of the fetal liver. II. Functional evaluation of an intraabdominal model.
To evaluate the use of the fetal liver as an auxiliary graft, we have developed a model of intraabdominal heterotopic transplantation of late gestational fetal lamb livers into weanling lambs. Thirty-eight transplants have been performed of which 31 were technically successful. Twenty-three grafts functioned for intervals of 5 to 22 days after transplantation. Grafts were functionally evaluated by analysis of total bile acid and bilirubin excretion. To determine whether host liver excretory function would influence function of the graft, common bile duct ligated recipients were compared with recipients with normal host liver function. We found that (1) intraabdominal auxiliary transplantation of the fetal lamb liver is technically feasible; (2) the fetal liver graft is capable of rapid adaptation and can assume a significant portion of host excretory function; and (3) excretory function of the fetal liver is proportional to the functional demands of the host. Auxiliary transplantation of the fetal liver is a promising alternative to current methods of liver transplantation.
Abdomen↗
Chronic nonspecific inflammatory bowel disease of the cecum and proximal colon in children with grossly normal-appearing colonic mucosa: diagnosis by colonoscopic biopsies.
The diagnosis of inflammatory bowel disease rests on radiologic, endoscopic, and histologic criteria. Five patients, 2 to 17 years of age, sought medical attention because of chronic abdominal pain, diarrhea, and heme-positive stools. Rectal biopsies, visual inspection of colonic mucosa through the colonoscope, and contrast radiographs of the large and small intestine yielded nonspecific results. Serial endoscopic biopsies demonstrated a gradient of inflammatory changes diminishing in severity distally from the ileocecal valve and cecum. The disease process was most evident in specimens from the cecum, whereas biopsies distal to the transverse colon had a normal histologic appearance in all five patients. Biopsies from the proximal colon may provide evidence of inflammatory bowel disease not detectable using standard techniques. The combination of chronic abdominal pain, diarrhea, and heme-positive stools associated with inflammatory changes in biopsy specimens obtained from the proximal colon, but normal findings on radiologic, colonoscopic, and rectal biopsy examinations, may represent an early stage in the evolution of chronic nonspecific inflammatory bowel disease, including ulcerative colitis or regional enteritis (Crohn disease).
Adolescent↗
Primary hemochromatosis in childhood.
Primary hemochromatosis is a genetic disorder rarely recognized in childhood; its long-term consequences include cirrhosis and liver cancer. We report a family with primary hemochromatosis affecting three generations, including a 7-year-old child and a 29-month-old child; these are the youngest children with primary hemochromatosis yet reported. The pathophysiology, genetics, and clinical findings of this disorder are reviewed. Serum ferritin and transferrin saturation are useful screening tests; definitive diagnosis, however, depends on determination of hepatic iron content. A plan for evaluating and treating affected patients is proposed. Physicians caring for children must learn to recognize this potentially treatable disorder.
Adult↗
Sclerosing cholangitis associated with chronic cryptosporidiosis in a child with a congenital immunodeficiency disorder.
Primary sclerosing cholangitis (PSC) in children is a rare and incurable disorder of unknown etiology. We report an immunodeficient child with chronic cryptosporidiosis of the biliary tract leading to clinical, pathological, and radiographic findings consistent with PSC. This case documents the ability of Cryptosporidium to disseminate to extraintestinal organs, and suggests that chronic cryptosporidial infection of the biliary tract may be one etiological mechanism producing sclerosing cholangitis in immunodeficient children. The increased incidence of PSC in immunodeficient children may in part be due to their inability to resolve infections of the biliary tract, which may result in sclerosing cholangitis mimicking PSC. We submit that an aggressive diagnostic workup should be performed to rule out an infectious etiology of sclerosing cholangitis in immunodeficient patients who have findings of PSC, because specific chemotherapy against the infecting organism would potentially arrest progressive biliary obliteration.
Adolescent↗
Alpha-fetoprotein levels in immunodeficiency.
Explore the source record for details and available documents.
Humans↗
Formation of bilirubin conjugates in human newborns.
Bilirubin conjugates in the serum of newborn human infants were investigated using the alkaline methanolysis-high-performance liquid chromatography method, a specific and sensitive method for measurement of unconjugated bilirubin and bilirubin mono- and diester conjugates. Serum samples were analyzed from 13 premature infants, 11 full term newborns, 22 healthy adults, seven pregnant women at term and their corresponding infants cord blood at delivery, 46 cord blood specimens obtained at unselected deliveries, three cord bloods from infants with maternal-fetal blood group incompatibility, and two cord bloods from infants with intrauterine hypoxia. Bilirubin conjugates were not detectable in the healthy adults, maternal blood, or in the cord blood specimens except from infants with blood group incompatibility or intrauterine hypoxia. The two isomeric monoconjugates of bilirubin appeared in serum during the first 24 to 48 postnatal h in both premature and full term infants, followed by the diconjugate on the 3rd day. Conjugated esters accounted for 2 to 5% of the total bilirubin, with the diconjugate constituting 21% of total conjugated pigment (day 3). In all instances, the unconjugated serum bilirubin concentration had increased to at least 2 mg/dl in the course of physiologic neonatal hyperbilirubinemia before bilirubin conjugates became detectable. Both premature and full term human infants displayed the identical pattern of bilirubin conjugation in serum.
Adult↗
Growth retardation in sickle-cell disease treated by nutritional support.
The effect of increased nutritional intake was evaluated in 5 growth-retarded children with sickle-cell disease. Growth on recommended daily calorie and protein intakes had been inadequate in all 5. Fat absorption and intestinal mucosal morphology were normal in all 5. 2 children were given nutritional supplementation by nasogastric intubation, 1 received nightly oral formula supplements, and 2 were supplemented with zinc, iron, folate, and vitamin E only. Nutritional supplementation by the nasogastric route produced a rapid sustained increase in growth rate, associated with striking reductions in pain crises and infections which had previously necessitated many hospital admissions. Oral supplementation improved the clinical course but had no effect on growth rate. Mineral and vitamin supplements influenced neither the growth rate nor the clinical course. The observations indicate that nasogastric nutritional supplementation may accelerate growth and reduce the incidence and severity of complications in growth-retarded children with sickle-cell disease.
Adolescent↗