Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The treatment of HIV infection has changed dramatically in recent years as a result of the development of new drugs which allows a variety of multitherapy combinations more adapted to patients' needs and thereby improving compliance. Efavirenz is a non-nucleoside reverse transcriptase inhibitor. In addition to a potent antiretroviral activity, efavirenz is an easy-to-take drug with once-daily dosing and is usually well tolerated. Efavirenz, however, may induce psychic alterations which are variable and atypical in both their clinical presentation and severity. As early as the first days of treatment, efavirenz may provoke surprising phenomena such as nightmares, vivid dreams, hallucinations or illusions, and twilight states. Depersonalization and derealization episodes, personality alterations, stream of thought troubles and unusual thought contents, atypical depression and cognitive disorders have also been observed. These phenomena may occur either early or later on treatment. The prevalence of severe psychic disorders is less than 5%, but they are often responsible for harmful treatment discontinuations. Psychiatric side effects are heterogeneous and probably not related to pre-existing psychologic weakness. We do not have enough data to evaluate these side effects and their etiopathogeny. The drug could act directly on the central nervous system since it crosses the blood-brain barrier, on the serotoninergic and dopaminergic systems. Some authors have compared efavirenz-induced psychic effects to those associated with LSD and found structural similarities between the two molecules. However, the heterogeneity and low prevalence of the psychiatric side effects of efavirenz suggest and individual sensitivity. In order to improve patient care, a better clinical approach, neuropsychological evaluation, and functional brain imagery should be used to progress in the analysis and comprehension of these disorders. We discuss in this paper the case of Mister H. This HIV-infected person presented with two severe melancholic episodes associated with marked cognitive disorders which resisted two successive antidepressant treatments (viloxazine and citalopram, respectively) prescribed at effective doses and for sufficient time duration. Mister H. had no personal or family psychiatric antecedent. His psychic condition improved only when efavirenz was discontinued. However, drug discontinuation may not be an obligatory step to improve the patient's condition since antidepressant treatment has been found effective in some similar situations. Actually, each case should be discussed with the clinicians taking care of the patient.
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PMID:[Apropos of atypical melancholia with Sustiva (efavirenz)]. 1148 60

Nucleoside analog reverse transcriptase inhibitors (NRTI) have been used to treat HIV-infected patients for >10 years. Some severe adverse events have been attributed to mitochondrial dysfunction. Since 1991, cases of severe lactic acidosis have been reported in association with nucleoside therapy. Our objective was to report two cases of metabolic acidosis and hepatic steatosis in patients receiving stavudine (d4T) and to review the literature. A male and a female, 47 and 45 years of age, respectively, presented with abdominal pain, nausea, vomiting, and weakness after 9 and 6 months, respectively, of treatment with stavudine. At presentation, both patients had severe metabolic acidosis and liver failure. Ultrasonography showed hepatic steatosis (confirmed by biopsy in one case). All antiretroviral drugs were withdrawn and patients were treated with bicarbonate. Both patients developed fulminant liver dysfunction and multiple organ failure. We reviewed the literature and found 75 cases of lactic acidosis and hepatic steatosis associated with use of NRTI; 57 of these patients received d4T (76%). Of all cases reported in association with nucleoside therapy, 63% were females and mortality was 47%. General weakness, hepatic enzyme elevation, and liver steatosis are data that should alert physicians to this serious adverse event and to respond with prompt interruption of antiretroviral drugs and measurement of lactic acid in plasma. It is important to report serious adverse events in commercially released drugs to know prevalence in an exposed population. Physicians should be aware of risk and early signs of this serious adverse event.
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PMID:Metabolic acidosis and hepatic steatosis in two HIV-infected patients on stavudine (d4T) treatment. 1260 78

A 55-year-old bat conservationist was admitted to Ninewells Hospital, Dundee, Scotland, on November 11, 2002, with an acute haematemesis. He gave a 5-day history of pain and paraesthesia in the left arm, followed by increasing weakness of his limbs with evidence of an evolving encephalitis with cerebellar involvement. The patient had never been vaccinated against rabies and did not receive postexposure treatment. Using a hemi-nested reverse transcriptase-polymerase chain reaction (RT-PCR), saliva samples taken intravitam from different dates proved positive for rabies. A 400-bp region of the nucleoprotein gene was sequenced for confirmation and identified a strain of European bat lyssavirus (EBLV) type 2a. The diagnosis was confirmed using the fluorescent antibody test (FAT) and by RT-PCR on three brain samples (cerebellum, medulla, and hippocampus) taken at autopsy. In addition, a mouse inoculation test (MIT) was performed. Between 13 and 17 days postinfection, clinical signs of a rabies-like illness had developed in all five inoculated mice. Brain smears from each infected animal were positive by the FAT and viable virus was isolated. This fatal incident is only the second confirmed case of an EBLV type-2 infection in a human after exposure to bats.
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PMID:Case report: isolation of a European bat lyssavirus type 2a from a fatal human case of rabies encephalitis. 1293 4

Genes encoding homeodomain-containing proteins potentially involved in endocrine pancreas development were isolated by combined in silico and nested-PCR approaches. One such transcription factor, Arx, exhibits Ngn3-dependent expression throughout endocrine pancreas development in alpha, beta-precursor, and delta cells. We have used gene targeting in mouse embryonic stem cells to generate Arx loss-of-function mice. Arx-deficient animals are born at the expected Mendelian frequency, but develop early-onset hypoglycemia, dehydration, and weakness, and die 2 d after birth. Immunohistological analysis of pancreas from Arx mutants reveals an early-onset loss of mature endocrine alpha cells with a concomitant increase in beta-and delta-cell numbers, whereas islet morphology remains intact. Our study indicates a requirement of Arx for alpha-cell fate acquisition and a repressive action on beta-and delta-cell destiny, which is exactly the opposite of the action of Pax4 in endocrine commitment. Using multiplex reverse transcriptase PCR (RT-PCR), we demonstrate an accumulation of Pax4 and Arx transcripts in Arx and Pax4 mutant mice, respectively. We propose that the antagonistic functions of Arx and Pax4 for proper islet cell specification are related to the pancreatic levels of the respective transcripts.
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PMID:Opposing actions of Arx and Pax4 in endocrine pancreas development. 1456 78

Ten crows (Corvus brachyrhynchos) and three blue jays (Cyanocitta cristata), species indigenous to North America, were intravenously inoculated with 10(3) PFU of West Nile virus (WNV) strain NY99 for production of positive tissues for Canadian surveillance. Both species developed clinical signs 4 days postinoculation (dpi). Virus was detected in blood, cloacal and tracheal swabs, and in a number of organs by reverse transcriptase-polymerase chain reaction (RT-PCR) and virus isolation (titers reaching over 10(7) PFU/0.1 g). Virus appeared as early as 1 dpi in blood (10(2)-10(3) PFU/ml) and spleen (10(3)-10(4) PFU/0.1 g of tissue), whereas kidney, liver, intestine, gonads, heart, skeletal muscle, and lung tested positive for WNV in a later stage of the infection. Immunostaining (IHC) using heterologous rabbit anti-WNV polyclonal antiserum detected viral antigen in a wide range of organs, starting at 2 dpi. Detection of WNV antigen in the brain of blue jays and crows by IHC was laborious as only few cells, not present in all sections, would stain positive. Mononuclear cells appeared to be an important target for virus replication, contributing to virus spread throughout tissues during the infection. This conclusion was based on the positive IHC staining of these cells in organs before virus antigen detection in parenchymal cells and supported by virus isolation and RT-PCR-positive results in white blood cells. The inability of blue jays and crows to perch and fly may reflect weakness due to generalized infection and marked skeletal muscle involvement, although involvement of the central nervous system cannot be excluded.
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PMID:Experimental West Nile virus infection in blue jays (Cyanocitta cristata) and crows (Corvus brachyrhynchos). 1523 36

Mitochondrial toxicity has been implicated in the development of a variety of nucleoside reverse transcriptase inhibitor-associated syndromes. Mitochondrial damage and decreases in mitochondrial DNA levels have been demonstrated in various tissues of patients treated with NRTIs, especially in conjunction with exposure to stavudine. Clinical syndromes that may be mediated by mitochondrial toxicity include hyperlactatemia and lactic acidosis, hepatic steatosis, lipoatrophy, peripheral neuropathy, HIV-associated neuromuscular weakness syndrome, pancreatitis, skeletal myopathies, and cardiomyopathy. Early recognition of these syndromes in their mild forms involves close monitoring and a high index of suspicion. This may allow prompt discontinuation of the causative agent(s) and initiation of appropriate therapeutic measures, thereby increasing the chances of reversibility of the syndrome.
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PMID:Mitochondrial dysfunction: patient monitoring and toxicity management. 1531 67

Because of recently reported reverse transcriptase polymerase chain reaction evidence of enterovirus in sporadic amyotrophic lateral sclerosis (SALS) and because of newly available anti-enteroviral drugs binding enteroviral capsids, it is reasonable to re-formulate an enteroviral hypothesis of SALS using recent advances in molecular virology. Viral persistence is non-lytic and non-cytopathic infection that evades host's immune surveillance. Enteroviruses are known to cause persistent as well as lytic infection both in vitro and in vivo. Both virion as well as host factors modulate between persistent and lytic infection. Apoptosis, or programmed cell death, is a process of active non-necrotic cell death. It has complex interplay with viruses and may be either promoted or opposed by them. Apoptosis is a major factor in motor neuron death in SALS. Viral tropism is the process by which viruses select and propagate to target cells. It is controlled by capsid conformation and surface receptors on host cells. Enteroviruses have a region on their capsids known as the canyon which docks on such receptors. Docking induces conformational changes of the capsid and genome release. Poliovirus, tropic for motor neurons, docks on the poliovirus receptor, about which much is known. The virus penetrates the motor system focally after crossing either the blood-muscle or the blood-brain barriers. It propagates bidirectionally along axons and synapses to contiguous motor neurons, upper as well as lower, which sequester infection and create avenues for spread over long distances. If chronic and persistent rather than acute and lytic, such viruses trafficking in a finite system of non-dividing cells and inducing apoptosis would cause cell death that summates linearly rather than exponentially. Taken together, these explain signature clinical features of SALS - focal onset weakness, contiguous or regional spread of weakness, confinement to upper and lower motor neurons, and linear rates of progression. The hypothesis predicts the following testable investigations: 1) viral detection may be possible by applying amplification technology to optimally acquired nervous tissue processed by laser microdissection; 2) genetic susceptibility factors such as cell surface receptor polymorphisms may combine with sporadic exposure and chance penetration of the motor system in SALS; 3) a transgenic animal model might be created by inserting such genetic factors into an animal host and inoculating intramuscularly rather than intracerebrally biochemical fractions of SALS motor neurons at vulnerable periods in the developmental life cycle of the transgenic host; and 4) continual long-term administration of anti-enteroviral agents called capsid-binding compounds which stabilize capsids and prevent genome release might be efficacious.
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PMID:Sporadic amyotrophic lateral sclerosis: a hypothesis of persistent (non-lytic) enteroviral infection. 1603 30

We report a case of Fanconi syndrome associated with the use of tenofovir disoproxil fumarate, a nucleotide reverse transcriptase inhibitor used in the treatment of HIV infection. A 56-year-old HIV-infected man was admitted to the hospital with a chief complaint of severe, progressive weakness. His HIV infection was well controlled by antiretroviral therapy; other medical problems included hepatitis C and chronic renal insufficiency. About 2 weeks before presentation, the patient had received an influenza vaccination, which was followed by a generalized viral syndrome of several days' duration. Next, weakness developed and culminated in an inability to walk; this prompted the patient's presentation at the hospital. Urine chemistry, electrolyte panel, and clinical presentation were consistent with Fanconi syndrome, a generalized proximal tubular dysfunction involving proteins, glucose, uric acid, and electrolytes. Along with our Case Report, we review 25 cases of Fanconi syndrome previously reported in the literature.
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PMID:Fanconi syndrome associated with use of tenofovir in HIV-infected patients: a case report and review of the literature. 1604 78

A 12-year-old male harbor seal presented with progressive signs of neurologic dysfunction including head tremors, muzzle twitching, clonic spasms, and weakness. Lesions included polioencephalomyelitis with glial nodules, spheroids, neuronophagia, ring hemorrhages, and a few neutrophils. Neurons, fibers, and glial nodules were multifocally colonized with intracytoplasmic West Nile flavivirus antigens that were demonstrated using indirect immunohistochemical analysis. Flavivirus on cultured cells also was isolated and was identified by use of monoclonal antibodies and reverse transcriptase-polymerase chain reaction analysis. Clinical signs of disease and lesion morphology and distribution were similar to those of equine West Nile virus infection. Similar to horses, alpacas, humans, dogs, and reptiles, seals can be dead-end hosts of West Nile virus.
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PMID:West Nile Flavivirus Polioencephalomyelitis in a harbor seal (Phoca vitulina). 1640 88

Dystrophin deficiency leads to the progressive muscle wasting disease Duchenne muscular dystrophy (DMD). Dystrophin-deficient mdx mice are characterized by skeletal muscle weakness and degeneration but they appear outwardly normal in contrast to DMD patients. Mice lacking both dystrophin and the dystrophin homolog utrophin [double knockout (dko)] have muscle degeneration similar to mdx mice, but they display clinical features similar to DMD patients. Dko limb muscles also lack postsynaptic membrane folding and display fiber-type abnormalities including an abundance of phenotypically oxidative muscle fibers. Extraocular muscles, which are spared in mdx mice, show a significant pathology in dko mice. In this study, microarray analysis was used to characterize gene expression differences between mdx and dko tibialis anterior and extraocular skeletal muscles in an effort to understand the phenotypic differences between these two dystrophic mouse models. Analysis of gene expression differences showed that upregulation of slow muscle genes specifically characterizes dko limb muscle and suggests that upregulation of these genes may directly account for the more severe phenotype of dko mice. To investigate whether any upregulation of slow genes is retained in vitro, independent of postsynaptic membrane abnormalities, we derived mdx and dko primary myogenic cultures and analyzed the expression of Myh7 and Myl2. Real-time reverse transcriptase-polymerase chain reaction analysis demonstrates that transcription of these slow genes is also upregulated in dko vs mdx myotubes. This data suggests that at least part of the fiber-type abnormality is due directly to the combined absence of utrophin and dystrophin and is not an indirect effect of the postsynaptic membrane abnormalities.
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PMID:Analysis of gene expression differences between utrophin/dystrophin-deficient vs mdx skeletal muscles reveals a specific upregulation of slow muscle genes in limb muscles. 1652 50


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