Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The point mutation in the tRNA(Lys) gene of mitochondrial DNA (mtDNA) from patients with myoclonic epilepsy and ragged red fibers (MERRF) was quantitatively analyzed after digestion with the restriction endonuclease Nae I of the PCR amplified DNA. Since the point mutation is not part of a restriction site for a commonly available restriction endonuclease, the Nae I restriction site was introduced by PCR using a mispairing primer. The percentage of mutated mtDNA was determined in a few hairs of five members of an affected family by counting the radioactivity of the fragments after PCR amplification with labelled dATP.
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PMID:Identification of point mutations by mispairing PCR as exemplified in MERRF disease. 212 85

The epilepsies affect at least 1 to 2 million people in the United States and 20 to 40 million people worldwide. Because the causes and basic mechanisms of the epilepsies have only started to unravel, there is still no cure for the disease. The purpose of this chapter is to present the new routes of navigation in epilepsy research, the salient theories on mechanisms of epilepsies, and their cogency to cause (generation of seizures) and effects (epileptic cell damage). In particular, it advances a comprehensible picture of the major cellular events involved in the generation, arrest, or spread of partial epileptic seizures; it also questions the major molecular events involved in the transmission and use of genetic information in the generalized epilepsies. In reviewing the many theories on mechanisms of epilepsies, this chapter establishes the connections between neurosciences, molecular genetics, and the epilepsies. The knowledge gained from such connections will certainly bear on the diagnosis of the subvarieties of epilepsies and is already promoting new methods of treatment of the disease. Indeed, it is this fusion between molecular genetics, neurosciences, and the clinical epilepsies that provides the excitement and new ferment in research of the epilepsies. This chapter also advances a conceptual blueprint for priority challenges in epilepsy research. It calls attention to the primary goal, namely, understanding the mechanisms of human epilepsies. In the most common of human epilepsies, namely, temporal lobe epilepsy, a priority challenge is to analyze paroxysmal depolarization shifts in hippocampal slices in vitro, slices excised from known sites of epileptogenicity. Parallel experiments exploring biochemical membrane abnormalities in neuronal and glial membranes isolated from the hippocampal seizure focus would be especially valuable. The role of kindling and the mirror focus in human temporal lobe epilepsy must be resolved. A second important goal is the search for polymorphisms of restriction endonuclease patterns in monogenic epilepsies in order to localize the abnormal gene to a specific chromosome. Because of the recent successful applications of positron emission tomography (PET), single-photon-emission computed tomography, and nuclear magnetic resonance computed tomography (NMR-CT), ion transport pathways, neurotransmitter systems, and metabolic processes may be constructed within the functioning brains of epileptic patients.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:New wave of research in the epilepsies. 287 20

In addition to yielding new routes of navigation, the workshops from which the material in this supplement comes developed a conceptual blueprint for priority challenges in epilepsy research. All participants called attention to the ultimate goal, namely, understanding the mechanisms of human epilepsies. And, foremost to achieving this goal is the search for polymorphisms of restriction endonuclease patterns in monogenic forms of epilepsies in an attempt to localize the abnormal gene, or genes, to a specific chromosome. In human temporal lobe epilepsy, a priority challenge is to record paroxysmal depolarization shifts in hippocampal slices in vitro, slices excised from the known site of epileptogenicity. Parallel experiments exploring biochemical membrane abnormalities in neuronal and glial membranes isolated from the hippocampal seizure focus are especially valuable. Together with genetic studies using restriction-fragment-length polymorphisms, these experiments should distinguish between the respective contributions of genetic and environmental factors in multifactorial forms of partial epilepsies, such as temporal lobe epilepsy. In the genesis and spread of human temporal lobe epilepsy, the role of kindling and the mirror focus must be resolved. Recent successful applications of positron emission tomography, single-photon-emission computed tomography, and nuclear magnetic resonance computed tomography show promise in finally constructing the ion transport pathways, neurotransmitter systems, and metabolic processes within the functioning brains of epileptic patients.
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PMID:The new wave of research in the epilepsies. 615 Jun 83

We describe a 15-year-old boy with full-blown mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) and chronic progressive external ophthalmoplegia (CPEO). He presented with visual disturbance, hearing impairment, continuous partial epilepsy on the right aspect of the face, and right hemiparesis since the age of 13. Four months later, he experienced another strokelike episode with continuous partial epilepsy on the left hand. Serial computed tomographic scans revealed bilateral parieto-occipital hypodense lesions with gyral enhancement and an additional low-density lesion in the right frontal area 4 months later, respectively. Results of laboratory examinations disclosed lactic acidosis and mitochondrial myopathy with many ragged-red fibers. To identify the defective gene in mitochondrial DNA, a simple molecular test was performed by using restriction endonuclease Apa I. A transition from A to G was found at nucleotide position 3243 of the tRNA(Leu) gene. Interestingly, the patient also had marked external ophthalmoplegia and ptosis commonly found in patients with CPEO. Therefore, we suggest that ophthalmoplegia also occurs in the MELAS syndrome.
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PMID:Ophthalmologic manifestations in MELAS syndrome. 836 52

In two German families four patients containing the A3243G mutant in the mitochondrial DNA suffered from maternally-inherited diabetes and deafness (MIDD). DNA was isolated from oral mucosa cells. Using the polymerase chain reaction with not yet published primers, we obtained after digestion with the restriction endonuclease BSP 1201 two oligonucleotides of comparable size increasing the sensitivity of our method two times. Under these conditions we were able to detect 0.8% of the mutated DNA. In general, the patients show the characteristics proposed for MIDD by Maassen et al. (1997), however, there are some differences: age at onset (in our study 36-45 y), body mass index (>26 kg/m2). In addition, our study shows that MIDD may be combined with neuronal disorders (M. Parkinson, epilepsy) and/or endocrinopathies (M. Addison). Our data indicate that MIDD is a heterogeneous disease. On the other hand, in one family there are healthy probands with a high concentration of mutated mitochondrial DNA.
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PMID:Maternally-inherited diabetes and deafness: report of two affected German families with the A3243G mitochondrial DNA mutation. 983 3

Status epilepticus (SE)-induced neuronal death is morphologically necrotic and is initiated by excessive glutamate release, which activates postsynaptic N-methyl-D-aspartate (NMDA) receptors and triggers receptor-mediated calcium influx (excitotoxicity). This results in activation of intracellular proteases and neuronal nitric oxide synthase, with generation of free radicals, and damage to cellular membranes, structural proteins, and essential enzymes. Programmed cell death mechanisms, such as p53 activation, activation of cell death-promoting Bcl-2 family members, and endonuclease-induced DNA laddering, occur in SE-induced neuronal death. Caspase-independent excitotoxic mechanisms, such as NMDA-induced calpain I activation, with activation and translocation of the cell death-promoting Bcl-2 family member Bid from cytoplasm to mitochondria, and subsequent translocation of apoptosis-inducing factor and endonuclease G to nuclei (which cause large-scale and internucleosomal DNA cleavage, respectively), may be triggered by SE. Poly(ADP-ribose) polymerase-1 (PARP-1) activation and cysteinyl cathepsin and DNase II release from lysosomes may occur following SE as well, but these events await future investigation. In the future, rational combinations of central nervous system-penetrable neuroprotective agents, based on our knowledge of excitotoxic mechanisms, may be useful in refractory human SE.
Epilepsy Behav 2005 Dec
PMID:Prolonged seizures and cellular injury: understanding the connection. 1627 99