Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019158 (hepatitis)
 30,205 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Liver sinusoids are special capillaries that are limited by fenestrated endothelial cells, without a genuine basement membrane, surrounded by perisinusoidal cells storing vitamin A, and harbouring Kupffer cells and pit cells, resident macrophages, and large granular lymphocytes, respectively. Each nonparenchymal cell and parenchymal cell of the liver interacts with all others and with the extracellular matrix. Therefore, the functional ability of each cell is constantly being modified by the metabolic activity of the others. Human liver biopsies (132), needle or surgical, perfusion-fixed with glutaraldehyde and processed for transmission electron microscopy (TEM), and occasionally for scanning electron microscopy (SEM), were examined. The study included liver diseases (such as alcoholic liver diseases, benign and malignant liver tumors, cholestasis of various origins, fulminant hepatitis, acute rejection after orthotopic liver transplantation, Budd-Chiari syndrome), as well as general or extrahepatic diseases (such as diabetes, hemochromatosis, hypervitaminosis A, various hematological disorders), and normal controls. Ultrastructural abnormalities are described and illustrated under two different headings: 1) elementary lesions of sinusoidal cells (endothelial, Kupffer, perisinusoidal and pit cells), nonsinusoidal cells (in the space of Disse and/or in the lumen), the extracellular matrix; and 2) the major pathological entities including perisinusoidal fibrosis, capillarization of sinusoids, sinusoidal dilatation, and peliosis. In the discussion, an overview of the major abnormalities reported in the literature is presented, and some specific questions regarding 1) perisinusoidal fibrosis in liver with normal histology, 2) the overload of perisinusoidal cells with lipids in non-hypervitaminosis A intoxication and 3) the etiological relationship of sinusoidal dilatation, peliosis, perisinusoidal fibrosis, or sinusoidal tumors with drugs and toxic compounds are discussed. In the event that lesions are not specific to any diagnosis, the knowledge of the ultrastructure of sinusoids is extremely useful from the perspective of the liver as an ecosystem.
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PMID:Fine structure of hepatic sinusoids and sinusoidal cells in disease. 233 89

A case of acute hypervitaminosis A complicating viral hepatitis is reported. Twenty days after presenting with hepatitis B, a 42-yr-old vegetarian developed acute hypervitaminosis A in the absence of recent, massive exposure to the vitamin. Findings included headache, confusion, skin desquamation, and hypercalcemia. Prior to developing hepatitis, he had ingested supplemental vitamin A without recognized ill effect. Liver and serum vitamin A without recognized ill effect. Liver and serum vitamin A levels were both elevated; the liver biopsy showed abundant, lipid-filled Ito cells and perisinusoidal fibrosis. This case demonstrates that patients with excessive hepatic stores of vitamin A may develop hypervitaminosis A during acute, intercurrent liver disease. Levels of retinol binding protein are reduced in hepatitis. This phenomenon may account for the findings in this case, since vitamin A is more toxic when not specifically bound to retinol binding protein. The size of the population at risk for this complication of hepatitis in unknown, but presumably it is growing with the widespread use of supplemental vitamin A.
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PMID:Hypervitaminosis A unmasked by acute viral hepatitis. 719 70

Mefloquine use has been linked to severe gastrointestinal and neuropsychiatric adverse effects, including cognitive disturbances, anxiety, depression, psychosis, and violence. The adverse effects of the drug are thought to result from the secondary consequences of hepatocellular injury; in fact, mefloquine is known to cause a transient, anicteric chemical hepatitis. However, the mechanism of mefloquine-associated liver damage and the associated neuropsychiatric and behavioral effects of the drug are not well understood. Mefloquine and other 8-amino-quinolines are the only antimalarial drugs that target the liver-stage malaria parasites, which selectively absorb vitamin A from the host. Vitamin A is also stored mainly in the liver, in potentially poisonous concentrations. These observations suggest that both the therapeutic effectiveness of mefloquine and its adverse effects are related to the ability of the 8-aminoquinolines to alter the metabolism of retinoids (vitamin A and its congeners). Several lines of evidence support the hypothesis that mefloquine neurotoxicity and other adverse effects reflect an endogenous form of hypervitaminosis A due to a process involving: mefloquine-induced dehydrogenase inhibition; the accumulation of retinoids in the liver; retinoid-induced hepatocellular damage; the spillage of stored retinoids into the circulation; and the transport of these compounds to the gut and brain in toxic concentrations. The retinoid hypothesis could be tested clinically by comparing cases of mefloquine toxicity and untreated controls in terms of retinoid profiles (retinol, retinyl esters, percent retinyl esters, and retinoic acid). Subject to such tests, retinoid profiling could provide an indicator for assessing mefloquine-associated adverse effects.
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PMID:Mefloquine use, psychosis, and violence: a retinoid toxicity hypothesis. 2385 88

Hepatic stellate cell (HSC) hyperplasia has been principally attributed to hypervitaminosis A. There are sporadic reports of HSC hyperplasia in other conditions such as chronic biliary disease and hepatitis C, but clinical associations of this entity have not been studied in detail. We aimed to investigate the clinical associations of HSC hyperplasia aside from hypervitaminosis A. We identified 34 patients whose liver histology showed HSC hyperplasia. We reviewed the liver samples; additional histologic findings in addition to HSC hyperplasia were consolidated into a histologic diagnosis. We collected clinical, laboratory, and radiologic data; the histologic diagnosis was combined with this data to reach an "overall diagnosis." Four patients had hypervitaminosis A (all native livers). In native livers (n = 24), HSC hyperplasia also occurred in association with drug-induced hepatitis [n = 6, niacin was the most common inducing agent (n = 3)], reactive hepatitis (n = 4), chronic hepatitis C (n = 4), autoimmune hepatitis (n = 3), steatohepatitis (n = 1), chronic biliary disease (n = 1), and portal venopathy (n = 1). In liver allografts (n = 10), HSC hyperplasia was seen in protocol biopsies without other significant abnormalities (n = 5), chronic biliary disease (n = 4), and acute cellular rejection (n = 1). All patients used medications (total of 99) and 82 % were on multiple medications. HSC hyperplasia is an uncommon and relatively nonspecific finding that most commonly occurs in multimedicated patients, often in the absence of hypervitaminosis A. Associated conditions include drug toxicity (such as niacin), post-liver transplant setting, reactive hepatitis (due to systemic illness or inflammatory disorders of the gastrointestinal tract), and chronic liver disease.
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PMID:Clinical associations of hepatic stellate cell (HSC) hyperplasia. 2480 74

A growing number of vaccines are administered at the same time or in close succession, increasing the complexity of assessing vaccine safety. Individual vaccines are assumed to have no other effect than protection against the targeted pathogen, but vaccines also have nonspecific and interactive effects, the outcomes of which can be beneficial or harmful. To date, no controlled trials and very few observational studies have determined the impact of vaccination schedules on overall health. The balance of the risks and benefits from mass vaccination therefore remains uncertain. Recent studies worryingly suggest links between multiple vaccinations and increased risks of diverse multisystem health problems, including allergies, infections, and neuropsychiatric or neurodevelopmental disorders. Here, we propose that, in susceptible persons, multiple vaccinations activate the retinoid cascade and trigger apoptotic hepatitis, leading to cholestatic liver dysfunction, in which stored vitamin A compounds (retinyl esters and retinoic acid) enter the circulation in toxic concentrations; this induces endogenous forms of hypervitaminosis A, with the severity of adverse outcomes being directly proportional to the concentration of circulating retinoids. In very low concentrations, vitamin A and its major metabolite retinoic acid contribute to immune function and to the process of immunization, whereas excess vitamin A increases the risk of adverse events, including common "side-effects" as well as chronic adverse outcomes. The increasing rates of allergy, ear infections, and neurodevelopmental disorders (NDDs) in countries with high rates of vaccination could be related to mass vaccination and to its impact on liver function and vitamin A metabolism, collectively representing endogenous manifestations of hypervitaminosis A. Further studies of health outcomes in vaccinated and unvaccinated groups are urgently needed, to increase understanding of the pathophysiology and treatment of vaccine injury, to identify the risk factors and screen for vaccine injury, to inform public health policy on potential hazards related to vaccination schedules, and to optimize the safety and benefits of vaccines.
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PMID:Multiple Vaccinations and the Enigma of Vaccine Injury. 3319 95