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)

HuD, one of the Hu antigens (HuD and HuC), was recognized in the sera of small cell lung cancer (SCLC) patients with antibody-associated paraneoplastic encephalomyelitis/peripheral sensory neuropathy (PEM/PSN). Three forms of HuD mRNA, 197, 156, 110 nucleotides are made by alternative splicing at 868-909 residues and an additional 3'-splice site. To determine the diagnostic value of the HuD expression for small cell lung cancer, we examined 4 SCLC cell lines, 9 surgically resected SCLCs, and 12 surgically resected non-SCLCs using the reverse transcriptase-polymerase chain reaction with the HuD-specific primer pairs that spanned the putative alternative 3'-splicing site and direct DNA sequencing. None of the patients were associated with PEM/PSN. A single RNA transcript (156 nucleotides) among three forms (110, 156, 197 nucleotides) of the HuD gene was an alternatively spliced at 868-909 residues in SCLC cell lines. Expression of the HuD gene was stronger in three classic cell lines, but not in a variant cell line. Two of 9 SCLCs (22%) and 3 of 12 non-SCLCs (25%) expressed only the major RNA transcript (156 nucleotides) of the HuD gene, which was alternatively spliced in the same fashion as the cell line. These results revealed that no aberrant alternative splicing occurred in SCLC not associated with PEM/PSN and the expression of HuD gene was not specific for a particular histologic subtype of human lung cancer.
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PMID:Expression of HuD (a paraneoplastic encephalomyelitis antigen) mRNA in lung cancer. 928 29

Two myelin proteins, P2 basic protein and P0 glycoprotein, can induce experimental autoimmune neuritis (EAN), a model of human inflammatory neuropathy. We investigated whether peripheral nerve myelin protein-22 (PMP22), the gene for which is duplicated in hereditary motor sensory neuropathy type la, can also induce EAN. PMP22 cDNA produced by the reverse transcriptase-polymerase chain reaction from rat sciatic nerve was expressed in Escherichia coli as a fusion protein with glutathione-S-transferase (GST). Ten Lewis rats were immunized with purified PMP22 fusion protein (50-100 microg) and eight controls with the same amount of GST. Two additional animals were immunized with each of two peptides (250 microg) of the human PMP22 extracellular sequences. Animals were examined daily until 20 days following immunization, when they underwent neurophysiological examination. A serum sample was then taken, prior to perfusion with glutaraldehyde and removal of the sciatic nerves and cauda equina. PMP22-immunized animals developed antibodies to the fusion protein and five out of 10 developed limp tails. No changes were observed in controls immunized with GST or in animals immunized with peptide. The mean compound motor action potentials elicited in the foot muscles by stimulation of the sciatic nerve at the sciatic notch and of the tibial nerve at the ankle were significantly reduced in the PMP22-immunized group (P < 0.05). Spinal roots from the group of animals immunized with PMP22 showed sparse infiltration of mononuclear cells, oedema and demyelination. PMP22 now deserves consideration as an autoantigen in human acute inflammatory demyelinating polyradiculoneuropathy.
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PMID:Induction of experimental autoimmune neuritis with peripheral myelin protein-22. 979 45

An HIV-infected man taking long-term zidovudine and didanosine presented with a polyphenotypic expression of nucleoside reverse transcriptase inhibitor (NRTI)-induced mitochondrial toxicity. Clinical features included lactic acidosis, myopathy, Fanconi-type proximal tubulopathy, pancreatic dysfunction, pseudo-obstruction, mega-oesophagus, peripheral sensory neuropathy and osteoporosis. A muscle biopsy showed morphologically abnormal mitochondria and respiratory chain biochemistry revealed marked reductions in the activity of respiratory chain enzymes containing mitochondrial DNA-encoded subunits. Southern blotting showed no mitochondrial DNA depletion and long PCR revealed only minor deletions. Following withdrawal of NRTI therapy, the lactic acidosis, pancreatic dysfunction and Fanconi's tubulopathy rapidly improved. Over the next 6 months there was marked improvement in osteoporosis, myopathy and neuropathy. At this stage, dual protease inhibitors and nevirapine were started. A repeat muscle biopsy 14 months after presentation showed normal morphology and respiratory chain biochemistry was almost normal.
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PMID:Polyphenotypic expression of mitochondrial toxicity caused by nucleoside reverse transcriptase inhibitors. 1292 44

To elucidate the underlying mechanisms involved in AIDS therapy-induced peripheral neuropathy, we have developed a model of nucleoside analog reverse transcriptase inhibitor-induced painful peripheral neuropathy in the rat, using 2',3'-dideoxycytidine (ddC), 2',3'-dideoxyinosine (ddI) and 2',3'-didehydro-3'-deoxythymidine (d4T), AIDS chemotherapeutic drugs that are also components of AIDS highly active anti-retroviral therapy. Administration of ddC, ddI and d4T produced dose-dependent mechanical hypersensitivity and allodynia. Peripheral administration of inhibitors of protein kinase A, protein kinase C, protein kinase G, p42/p44-mitogen-activated protein kinase (ERK1/2) and nitric oxide synthase, which have demonstrated anti-hyperalgesic effects in other models of metabolic and toxic painful peripheral neuropathies, had no effect on ddC-, ddI- and d4T-induced hypersensitivity. Since suramin, an anti-parasitic and anti-cancer drug, which shares with the anti-retroviral nucleoside analogs, mitochondrial toxicity, altered regulation of intracellular calcium, and a sensory neuropathy in humans, also produced mechanical hypersensitivity that was not sensitive to the above second messenger inhibitors we evaluated the role of intracellular calcium. Intradermal or spinal injection of intracellular calcium modulators (TMB-8 and Quin-2), which had no effect on nociception in control rats, significantly attenuated and together eliminated ddC and suramin-induced mechanical hypersensitivity. In electrophysiology experiments in ddC-treated rats, C-fibers demonstrated alterations in pattern of firing as indicated by changes in the distribution of interspike intervals to sustained suprathreshold stimuli without change in mechanical activation thresholds or in number of action potentials in response to threshold and suprathreshold stimulation. This study provides evidence for a novel, calcium-dependent, mechanism for neuropathic pain in a model of AIDS therapy-induced painful peripheral neuropathy.
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PMID:Novel mechanism of enhanced nociception in a model of AIDS therapy-induced painful peripheral neuropathy in the rat. 1471 1

The objective of this study is to examine the risk factors associated with the development of sensory neuropathy in human immunodeficiency virus (HIV)-infected patients in 292 HIV+ patients recruited through a community-based sentinel survey. We determined the clinical and treatment factors associated with the presence of peripheral sensory neuropathy in HIV+ subjects at baseline examination, and at 1-year follow-up. Baseline examination was assessed with a logistic regression analysis controlling for age, education level, history of drug/alcohol use, and anti-retroviral treatment. The risk of developing new peripheral neuropathy at follow-up was determined using a Cox proportional hazard model analysis. At study entry, neuropathy (n=64) was associated with acquired immunodeficiency syndrome (AIDS), nucleoside analogue reverse transcriptase inhibitors (NRTI) (i.e. ddC), and history of alcohol abuse. After 1-year follow-up, the development of neuropathy was predicted by AIDS, age (older subjects), and NRTI use. These findings indicated that AIDS, age, alcohol abuse/dependence, and anti-retroviral medication use are important predictors of motor/sensory peripheral neuropathy in the HIV infection. The peripheral neurotoxic effect of anti-retroviral medication should be taken into account in the design of long-term therapies.
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PMID:Risk modifiers for peripheral sensory neuropathy in HIV infection/AIDS. 1474 69

Many commonly used medications have neurotoxic adverse effects; the most common of these is peripheral neuropathy. Neuropathy can be a dose-limiting adverse effect for many medications used in life-threatening conditions, such as malignancy and HIV-related disease. Epidemiological evidence supports previous case reports of HMG-CoA reductase inhibitors (or 'statins') causing an axonal sensorimotor neuropathy or a purely small-fibre neuropathy in some patients. The neuropathy improves when the medication is withdrawn. Despite the association between HMG-CoA reductase inhibitors and neuropathy, the risk is low compared with the significant vascular protective benefits. Oxaliplatin, a new platinum chemotherapy agent designed to have fewer adverse effects than other such agents, has been shown to cause a transient initial dysaesthesia in addition to an axonal polyneuropathy. Thalidomide, an old therapy currently being utilised for new therapeutic indications (e.g. treatment of haematological malignancies), is associated with a painful, axonal sensorimotor neuropathy that does not improve on withdrawal of the drug. Nucleoside reverse transcriptase inhibitors are important components of highly active antiretroviral therapy, but are associated with a sensory neuropathy that is likely to be due to a direct effect of these drugs on mitochondrial DNA replication. New research demonstrates that lactate levels may help discriminate between neuropathy caused by nucleoside analogues and HIV-induced neuropathy. Understanding the mechanism of drug-induced neuropathy has led to advances in preventing this disabling condition.
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PMID:Advances in understanding drug-induced neuropathies. 1645 32

A toxic sensory neuropathy associated with exposure to inexpensive nucleoside analogue reverse transcriptase inhibitors (NRTIs) [particularly stavudine (d4T)] causes dilemmas in the management of patients with HIV, especially in resource-poor settings. Here patients (n = 96) attending Pokdisus AIDS Clinic at the Cipto Mangunkusumo Hospital, Jakarta who had been treated with d4T were screened for symptomatic neuropathy. Clinical, demographic, and genetic factors were considered as possible neuropathy risk factors. DNA from saliva was used to examine alleles of TNFA-308, BAT1 (intron 10), TNFA-1031, IL1A+4845, and IL12B (3' UTR). The prevalence of neuropathy (symptoms and signs) was 34%. On multivariate analysis, neuropathy following d4T exposure was associated with increasing age, increasing height, and TNFA-1031*2 (model p = 0.0009). Isoniazid exposure (present in 56% of patients) was not associated with neuropathy in this cohort, where all patients had received pyridoxine coadministration. These data suggest that a simple algorithm based on patient age, height, and TNF genotype could be used to predict the individual's risk of symptomatic neuropathy prior to prescription of d4T.
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PMID:Can we predict neuropathy risk before stavudine prescription in a resource-limited setting? 1883 21

HIV-associated sensory neuropathy is the most frequent manifestation of HIV disease, afflicting 40-50% of patients whose HIV disease is otherwise controlled by antiretroviral therapy. It often presents with significant neuropathic pain and is consistently associated with previous exposure to nucleoside reverse transcriptase inhibitors including stavudine (d4T), which is widely used in resource-limited settings. Here we investigated complex pain-related behaviours associated with d4T treatment using ethologically relevant thigmotaxis and burrowing behaviours in adult rats. Detailed neuropathological response was also examined using neurochemistry, electron microscopy, and proteomics. After 2 intravenous injections of d4T (50 mg/kg, 4 days apart), rats developed hind paw mechanical hypersensitivity, which plateaued at 21 days after initial d4T injection, a time that these animals also had significant changes in thigmotaxis and burrowing behaviours when compared to the controls; reductions in hind paw intraepidermal nerve fibre density and CGRP/IB4 immunoreactivity in L5 spinal dorsal horn, suggesting injury to both the peripheral and central terminals of L5 dorsal root ganglion neurons; and increases in myelinated and unmyelinated axon diameters in the sural nerve, suggesting axonal swelling. However, no significant glial and inflammatory cell response to d4T treatment was observed. Sural nerve proteomics at 7 days after initial d4T injection revealed down-regulated proteins associated with mitochondrial function, highlighting distal axons vulnerability to d4T neurotoxicity. In summary, we have reported complex behavioural changes and a distinctive neuropathology in a clinically relevant rat model of d4T-induced sensory neuropathy that is suitable for further pathophysiological investigation and preclinical evaluation of novel analgesics.
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PMID:A clinically relevant rodent model of the HIV antiretroviral drug stavudine induced painful peripheral neuropathy. 2341 9

Peripheral neuropathy is a common and vexing symptom for people living with HIV infection (PLWH). Neuropathy occurs in several different syndromes and is identified in the literature as distal sensory polyneuropathy or distal sensory peripheral neuropathy. More recently, the HIV literature has focused on the syndrome as painful HIV-associated sensory neuropathy, addressing the symptom rather than the underlying pathophysiology. Assessment of neuropathy in PLWH is critical and must be incorporated into nursing practice for each visit. Neuropathy has been attributed to the direct effects of HIV, exposure to antiretroviral medications (particularly the nucleoside reverse transcriptase inhibitors), advanced immune suppression, and comorbid tuberculosis infection and exposure to antituberculosis medications. Evidence supports the importance of addressing neuropathy in PLWH with pharmacologic treatment regimens and complementary/alternative approaches. This paper examines the pathophysiology, evidence, and approaches to managing peripheral neuropathy. A case study has been included to illustrate a patient's experience with neuropathy symptoms.
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PMID:Peripheral neuropathy in HIV: an analysis of evidence-based approaches. 2469 31

HIV-associated sensory neuropathy (HIV-SN) is the most frequent manifestation of HIV disease. It often presents with significant neuropathic pain and is associated with previous exposure to neurotoxic nucleoside reverse transcriptase inhibitors. However, HIV-SN prevalence remains high even in resource-rich settings where these drugs are no longer used. Previous evidence suggests that exposure to indinavir, a protease inhibitor commonly used in antiretroviral therapy, may link to elevated HIV-SN risk. Here, we investigated whether indinavir treatment was associated with the development of a "dying back" axonal neuropathy and changes in pain-relevant limb withdrawal and thigmotactic behaviours. After 2 intravenous injections of indinavir (50 mg/kg, 4 days apart), adult rats developed hind paw mechanical hypersensitivity, which peaked around 2 weeks post first injection (44% reduction from baseline). At this time, animals also had (1) significantly changed thigmotactic behaviour (62% reduction in central zone entries) comparing with the controls and (2) a significant reduction (45%) in hind paw intraepidermal nerve fibre density. Treatment with gabapentin, but not amitriptyline, was associated with a complete attenuation of hind paw mechanical hypersensitivity observed with indinavir treatment. Furthermore, we found a small but significant increase in microglia with the effector morphology in the lumbar spinal dorsal horn in indinavir-treated animals, coupled with significantly increased expression of phospho-p38 in microglia. In summary, we have reported neuropathic pain-related sensory and behavioural changes accompanied by a significant loss of hind paw skin sensory innervation in a rat model of indinavir-induced peripheral neuropathy that is suitable for further pathophysiological investigation and preclinical evaluation of novel analgesics.
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PMID:A rodent model of HIV protease inhibitor indinavir induced peripheral neuropathy. 2768 9


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