Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0040822 (tremor)
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Mexiletine is a Class IB antiarrhythmic which has basic and clinical electrophysiologic properties similar to lidocaine. Like other Class I antiarrhythmic agents, mexiletine blocks the rapid inward sodium current responsible for phase 0 of the action potential. It has been noted in the clinical electrophysiology laboratory to have minimal effect on sinus node function and AV nodal and His-Purkinje system conduction. Pharmacokinetic studies have shown that oral absorption is rapid with bioavailability of 80-90%. Mexiletine is predominantly metabolized by the liver with elimination half-life of 9 to 12 hours. The antiarrhythmic effects of the primary drug's metabolites remain to be defined. Hemodynamic studies have shown mexiletine to have a lesser negative inotropic effect than procainamide or disopyramide. Although mexiletine as a single agent successfully suppresses 60 to 80% of spontaneous ventricular arrhythmias, it has lower efficacy in suppression of induced ventricular arrhythmias. Multiple studies have shown that as monotherapy mexiletine is effective in preventing the induction of ventricular tachycardia in approximately 20% of patients. When used in combination with a Class IA antiarrhythmic drug for suppression of induced ventricular arrhythmias, multiple investigators have reported greater efficacy. Neurological side effects (tremor, dizziness, memory loss) occur in approximately 10% of patients while gastrointestinal side effects (nausea, anorexia, gastric irritation) occur in up to 40% of patients. Proarrhythmia or other serious toxicity from the drug is uncommon.
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PMID:Mexiletine: pharmacology and therapeutic use. 218 14

Alzheimer's disease (AD) is a heterogeneous entity presenting as sporadic and familial disease. In familial AD, there is evidence for genetic linkage to a yet undefined gene on chromosome 14 in early-onset pedigrees and on chromosome 19 in late-onset pedigrees. In a few early-onset kindreds, there were mutations in the amyloid precursor gene on chromosome 21. There is an increased frequency of apolipoprotein E (ApoE) epsilon4 allele in patients with late-onset AD. We studied the clinical presentation and profile of cognitive deficits in 58 AD patients at the early stage of the disease. We divided the AD patients into subgroups of sporadic late-onset (SLO) (> or = 65 years), familial late-onset (FLO) (> or = 65 years), sporadic early-onset (SEO) (<65 years), and familial early-onset (FEO) (<65 years) patients and into three subgroups according to their ApoE genotype zero epsilon4, one epsilon4, and two epsilon4 alleles. The AD subgroups did not differ in the global clinical severity of dementia or the duration of the disease. SLO, FLO, SEO, and FEO subgroups did not differ in clinical characteristics such as occurrence of rigidity, hypokinesia, tremor, myoclonus, hallucinations, delusions, or epileptic seizures nor in the profile of deficits on tests assessing memory, language, visuospatial, executive, and praxic functions. The epsilon4++ allele frequency was 0.43 for all AD patients and did not differ across subgroups divided according to the familial aggregation and age of onset. Patients with two epsilon4 alleles had earlier age at onset of dementia than those with no epsilon4 allele (63 +/- 9 versus 68 +/- 9 years), but otherwise the clinical symptoms and signs were not related to the ApoE genotype. However, the AD patients with two epsilon 4 alleles had lowest scores on memory tests and differed significantly from those with one or zero epsilon4 allele in the delayed list learning (p<0.05) and from those with zero epsilon4 allele in the immediate and delayed story recall. In contrast, verbal functions were better preserved in two epsilon4 patients than in those with other ApoE genotypes. This study failed to confirm the earlier reports of severe aphasia, agnosia, and apraxia in familial AD patients, but the clinical phenotype was similar irrespective to the familial aggregation. However, AD patients with two epsilon4 alleles are characterized by more severe memory loss and earlier age of onset than those without the epsilon4 allele.
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PMID:Clinical and neuropsychological characteristics in familial and sporadic Alzheimer's disease: relation to apolipoprotein E polymorphism. 861 4

We report a 63-year-old woman who presented myotonia and parkinsonism. The patient was well until 15 years of the age when she noted that the ring finger of her left hand at times flexed when she did not intend to do so. She noted weakness in her left upper extremity at the age of 40, and difficulty in relaxing her hand grip at 45. She had an onset of tremor in her right foot at age 50, which was followed by difficulty in gait and hand writing. She was admitted to Juntendo University Urayasu Hospital when she was 63-year-old. Her mother, two sisters, and a son were affected with similar muscle weakness and myotonia. Although some of them developed stooped posture in the late stage of the disease, none of them had overt parkinsonism. General physical examination was unremarkable. Neurologic examination revealed an alert and oriented woman with some recent memory loss. She had bilateral ptosis, facial weakness, and a masked face. Myerson's sign was present. Her speech was small and monotonous. The sternocleidomastoid muscles were markedly atrophic and weak. The remaining of the cranial nerves were intact. She walked in small steps with freezing with support. She showed bradykinesia, retropulsion, and resting tremor in her right leg. Slight distal dominant weakness was noted in both upper and lower extremities more on the left. No cerebellar signs were noted. Muscle stretch reflexes were within normal limits in the upper extremities and diminished in the lower limbs. Sensation was intact. Routine laboratory findings were unremarkable. Cranial CT scan and MRI revealed slight cortical atrophy and leukoaraiosis. She responded to levodopa and she became able to walk by herself. She was transferred to another hospital one month after her admission. She had several bouts of airway obstruction with one episode of respiratory arrest. She expired six month after the transfer. The patient was discussed in a neurological CPC, and the chief discussant arrived at the conclusion that this patient suffered from myotonic dystrophy and Parkinson's disease which set in later years. Postmortem examination on the iliopsoas muscle revealed uneven muscle fiber diameters, central nuclei, and type 1 fiber predominance; the pathologic finding was consistent with myotonic dystrophy. The substantia nigra showed marked cell loss and Lewy bodies in the remaining neurons. The finding was consistent with Parkinson's disease. In myelin stain, diffuse myelin pallor was noted in the cerebral white matter which was the pathologic substrate of leukoaraiosis in this patient. Combination of these two disorders have never been reported in the literature to our knowledge. It appears to be that the coincidence is just a by-chance phenomenon, but it seems interesting to note that accelerated aging process appears to be present in both myotonic dystrophy and Parkinson's disease.
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PMID:[A 63-year-old woman with muscle weakness, myotonia, and parkinsonism]. 886 42

We report a 70-year-old man with progressive gait disturbance and gaze palsy. The patient was well until summer of 1991 when he was 66-year-old, when he noted a gradual onset of difficulty in gait and looking downward. He was evaluated in our hospital in May, 1994 when he was 69-year-old. On admission, he was alert but markedly demented with disorientation and memory loss. Constructional apraxia and dressing apraxia were noted. He had difficulty in gaze to all directions; he could move his eyes only 20% of the normal range. Oculocephalic response was retained. He had small voice and some dysphagia. Other cranial nerves were unremarkable. He could not walk unsupported. Marked retropulsion was noted in which he would fell down spontaneously upon standing unless supported. Moderate to marked rigidity was noted in the neck, trunk, and in the legs, however, in the upper extremities, rigidity was only mild. No tremor was noted. Deep reflexes were symmetrically exaggerated with ankle clonus bilaterally. Plantar response was flexor. Sensation was intact. Routine laboratory tests were unremarkable, however, his cranial MRI showed moderate to marked fronto-temporal atrophy and moderate midbrain and pontine tegmental atrophy. The third ventricle was markedly dilated. He was discharged for out patient care, however, his dysphagia had become progressively worse, and he suffered from frequent bouts of pneumonia. He was admitted to our service on October 17, 1994. His neurologic examination was essentially similar except that he showed more advanced dementia. He was still able to stand with support. Gastrostomy was placed on October 25. Post-operative course was unremarkable. He was discharged on November 1. His motor disturbance showed gradual deterioration, and by the May of 1995, he became bed-ridden, and was admitted to another hospital on May 30, 1995. He was almost totally unable to move his eyes, but oculocephalic response was still elicited. Marked truncal and limb rigidity were noted. He vomited coffee-ground substance on October 31, 1995, and developed hypotension. The subsequent course was complicated by pneumonia and he expired on November 24. The patient was discussed in a neurological CPC. Majority of the participants thought that the patient had progressive supranuclear palsy, but some participants thought that the patient had corticobasal degeneration because cortical atrophy was so marked. Post mortem examination revealed atrophy of the frontal and parietal lobe. The brain stem was atrophic particularly in the tegmental area including the midbrain. The substantia nigra showed marked neuronal loss and globose type neurofibrillary tangles in the remaining neurons. The neurons in the locus coeruleus was well retained, however neurofibrillary tangles were seen. In addition, the cerebellar dentate nucleus, the inferior olivary nucleus, and the internal globus pallidus showed marked neuronal loss and neurofibrillary degeneration. In the frontal cortex, although macroscopic examination showed some atrophy, microscopic examination failed to show neuronal loss or gliosis. The pathologic findings were consistent with the diagnosis of progressive supranuclear palsy.
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PMID:[A 70-year-old man with a progressive gait disturbance and gaze palsy]. 902 10

We report a 83 year-old woman with dementia. She was apparently well until December of 1993 when she was 81-year-old. At that time, she was operated or her cataract. Her post operative course was uneventful, however, shortly after her operation, she had an onset of memory loss and abnormal behavior. She showed a fluctuating course in her mental disturbance. In 1995, her dementia worsened with nocturnal agitation. She was admitted to our service on June 12, 1995. She was alert and her blood pressure was 140/100 mmHg. She showed recent memory loss and disorientation to time. Motor wise, she was unable to stand unsupported. Her gait with support showed small steps and a wide base. She was bradykinetic and ataxic in her finger-to-nose and heel-to-knee test, however, no rigidity or tremor was noted. Her MRI showed T2-high signal lesions in both medial thalamic areas, in the right occipital lobe, and in the bilateral cerebral white matters as well as in the basal ganglia. She was discharged for out-patient follow up on July 3, 1995. Four days after the discharge, she showed declining responses to stimuli and she developed dyspnea on July 14, 1995. She was admitted again on the same day. Her body temperature was 38.5 degrees C and moist rales were heard in the left lung field. She appeared drowsy and no verbal response was obtained; no apparent motor palsy was noted. Blood count showed leukocytosis (14,300/ml). Blood gas analysis under 61 of oxygen inhalation through a mask was as follows: pH 7.460, PCO2 39.6 mmHg, PO2 67 mmHg, and HCO3-28.5 mEq/l. Two days after admission, she developed a convulsion in her left arm and she became unconscious. Her EEG showed periodically recurring lateralized epileptic discharges on the right fronto-central areas. Her subsequent course was complicated by status epilepticus and respiratory distress. She died on July 26, 1995. She was discussed in a neurological CPC. The chief discussant arrived at a conclusion that she suffered from multi-infarct dementia. Bilateral thalamic infarctions were considered to have played a significant role in her dementia. Post-mortem examination revealed subcortical leukoencephalopathy of Binswanger's type and cerebral infarctions in the thalamic and basal ganglia regions and in the right occipital lobe. In addition, she showed isolated angitis of the central nervous system involving mainly in the small arteries located in the superficial areas of the brain and the spinal cord. This patient was interesting in that despite relatively mild leukoaraiosis in MRI, post-mortem examination revealed profound pathologic changes in the subcortical white matters. In addition, she showed the isolated angitis of the CNS. The cause and the clinical correlates of her angitis were unclear.
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PMID:[A 83 year-old woman with dementia, gait disturbance, and convulsion]. 904 33

Fifty-three UK and 59 USA people with multiple sclerosis (MS) answered anonymously the first questionnaire on cannabis use and MS. From 97 to 30% of the subjects reported cannabis improved (in descending rank order): spasticity, chronic pain of extremities, acute paroxysmal phenomenon, tremor, emotional dysfunction, anorexia/weight loss, fatigue states, double vision, sexual dysfunction, bowel and bladder dysfunctions, vision dimness, dysfunctions of walking and balance, and memory loss. The MS subjects surveyed have specific therapeutic reasons for smoking cannabis. The survey findings will aid in the design of a clinical trial of cannabis or cannabinoid administration to MS patients or to other patients with similar signs or symptoms.
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PMID:The perceived effects of smoked cannabis on patients with multiple sclerosis. 925 98

HIV-associated neurological manifestations: dementia, myelopathy, and neuropathy, have become one of the commonest causes of neurological disorders in young people. Cognitive impairment develops in about 30 p. 100 of patients with AIDS and frank dementia in 15 to 20 p. 100 with an annual incidence after AIDS of approximatively 7 p. 100. Typically, the onset of dementia is relatively abrupt over a few weeks or months. The clinical manifestations of the encephalopathy now termed "HIV-dementia", suggest predominant subcortical or frontal involvement. Typical presentation includes apathy and inertia, memory loss and cognitive slowing, minor depressive symptoms and withdrawal from usual activities. Neurological examination may show hypertonia of lower limbs, tremor, clonus, frontal release signs and hyperactive reflexes. Terminally, the patient is bedbound, incontinent, abulic or mute with decorticate posturing leading to death over 3 to 6 months. However, a stabilisation and even a regression of the cognitive disorders have been observed following antiretroviral treatment. Radiological features of HIV dementia include both central and cortical atrophy and white matter rarefaction. However they are neither invariable nor specific. Together with CSF examination, they are more important to exclude opportunistic infections. Indeed, although a completely normal CSF profile may reasonably exclude the diagnosis; at present, no single test or combination of tests can reliably diagnose HIV dementia. Although the clinical characteristics of HIV-dementia are now clearly established, its pathogenesis is unclear and its pathological counterpart remains a matter of debate. A number of "HIV-induced" lesions may be found in the brain of AIDS patients and their causative role in HIV-dementia has been considered. They include HIV encephalitis due to productive CNS infection by the virus, diffuse white matter pallor "HIV-leukoencephalopathy" reflecting an abnormality of the blood brain barrier, involvement of the grey matter, "diffuse poliodystrophy", with neuronal loss that results, at least partly, from a process of programmed cell death and axonal damage. These changes are variably associated in patients with HIV dementia, however none of them can be closely related to the cognitive disorders. This suggests that the neuronal dysfunction underlying HIV-dementia results from different mechanisms that are variably associated and may interact mutually. These include production of viral proteins, microglial activation with consequent production of neurotoxic factors such as proinflammatory cytokines, free radicals, derivates of arachidonic acid, or quinoleic acid, and blood borne neurotoxic factors in particular cytokines.
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PMID:[Dementia and human inmmunodeficiency virus infection]. 983 49

It was observed by Couper in 1837 that manganese dust produces a neurological syndrome characterized by muscle weakness, tremor, bent posture, whispered speech and excess salivation. The similarity of these symptoms to those of Parkinson's disease were not recognized for many years. In addition to its Parkinson-like effects, manganese produces behavioral symptoms in humans including nervousness, hallucinations, memory loss, cognitive problems, bizarre behaviors and flight of ideas. Despite these signs and symptoms, there have been few systematic attempts to study the effects of manganese on behavior using animal models. The need to better understand the effects of manganese on behavior is becoming more important due to the potential of increased environmental exposure to manganese due to its use, or proposed use as a gasoline additive in a number of countries. However, there is debate as to which manganese compounds should receive priority for testing, what route of administration should be used in this testing, what dosing regimens should be used, what species are appropriate for behavioral testing, and what behavioral tests should be selected. Research to answer these questions is needed so that the behavioral effects of manganese can be described comprehensively and the mechanisms underlying these effects can be understood.
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PMID:A brief history of the neurobehavioral toxicity of manganese: some unanswered questions. 1038 8

Mercury exists in various chemical forms. The important forms from a toxicological viewpoint are the metallic form, also called the elemental form, the divalent inorganic forms and methylmercury compounds. Elemental (Hg0) mercury has a high vapor pressure and the vapor causes a number of cases of poisoning via inhalation. Classical mercury poisoning is characterized by a triad of signs, namely tremors, erethism and gingivitis. Mercurial erethism, which is characterized by behavioral and personality changes such as extreme shyness, excitability, loss of memory, and insomnia are also observed. Recently, the effects of mercury exposure at levels around 0.05 mg/m3 or lower have been of concern and may include minor renal tubular damage, increased complaints of tiredness, memory disturbance and other symptoms, subclinical finger tremor, abnormal EEG by computerized analysis and impaired performance in neurobehavioral or neuropsychological tests. Abnormal gait, dysarthria, ataxia, deafness and constriction of the visual field are typical of the symptoms of methylmercury poisoning observed in Minamata and Iraqi outbreaks, as well as in occupational methylmercury poisoning cases. Furthermore, an infant born to a mother with excessive methylmercury consumption showed various neurological disturbances and delayed development. Since several populations are believed to be still exposed to methylmercury through the consumption of fish and sea mammals, neurobehavioral deviations in children of these populations have recently been investigated.
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PMID:Occupational and environmental toxicology of mercury and its compounds. 1081 38

The region of Diwalwal, dominated by Mt. Diwata, is a gold rush area on Mindanao (Philippines) where approximately 15000 people live. The fertile plain of Monkayo is situated downstream, where people grow crops such as rice and bananas; locally caught fish is eaten frequently. The ore is dug in small-scale mines and ground to a powder by ball-mills while still in Diwalwal. The gold is then extracted by adding liquid mercury (Hg), forming gold-amalgam. To separate the gold from the Hg, in most cases the amalgam is simply heated in the open by blow-torches. A high external Hg burden of the local population must be assumed. To evaluate the internal Hg burden of the population and the extent of possible negative health effects, 323 volunteers from Mt. Diwalwal, Monkayo and a control group from Davao were examined by a questionnaire, neurological examination and neuro-psychological testing. Blood, urine and hair samples were taken from each participant and analyzed for total Hg. A statistical evaluation was possible for 102 workers (occupationally Hg burdened ball-millers and amalgam-smelters), 63 other inhabitants from Mt. Diwata ('only' exposed from the environment), 100 persons, living downstream in Monkayo, and 42 inhabitants of Davao (serving as controls). The large volume of data was reduced to yes/no decisions. Alcohol as a possible bias factor was excluded (level of alcohol consumption and type, see Section 4.4). Each factor with a statistically significant difference of at least one exposed group to the control group was included in a medical score (0-21 points). In each of the exposed groups this score was significantly worse than in the control group (median control, 3; downstream, 9; Mt. Diwata, non-occupational exposed, 6; Hg workers, 10). In comparison to the surprisingly high Hg concentration in blood (median, 9.0 microg/l; max, 31.3) and in hair (2.65 microg/g; max, 34.7) of the control group, only the workers show elevated levels: Hg-blood median 11.4, max 107.6; Hg-hair median 3.62, max 37.8. The Hg urine concentrations of the occupational exposed and non-exposed population on Mt. Diwata was significantly higher than in the control group: control median 1.7 microg/l, max 7.6; non-occupational burdened median 4.1, max 76.4; and workers median 11.0, max 294.2. The participants, living downstream on the plain of Monkayo show no statistically significant difference in Hg-blood, Hg-urine or Hg-hair in comparison with the control group. The German Human-Biological-Monitoring value II (HBM II) was exceeded in 19.5% (control), 26.0% (downstream), 19.4% (Mt. Diwata, non-occupational) and 55.4% (workers) of the cases, the German occupational threshold limit in 19.6% of the workers. Only some of the clinical data, characteristic for Hg intoxication (e.g. tremor, loss of memory, bluish discoloration of the gingiva, etc.), correlate with Hg in blood or urine, but not with Hg in hair. The medical score sum correlates only with Hg in urine. The poor correlation between the Hg concentration in the biomonitors to classic clinical signs of chronic Hg intoxication may be explained by several factors: Hg in blood, urine and hair do not adequately monitor the Hg burden of the target tissues, especially the brain. Inter-individual differences in the sensitiveness to Hg are extremely large. In this area a mixed burden of Hg species must be assumed (Hg vapor, inorganic Hg, methyl-Hg). Chronic Hg burden may have established damage months or even years before the actual determination of the Hg concentrations in the bio-monitors under quite different burden was performed (Drasch G. Mercury. In: Seiler HG, Sigel A, Sigel H, editors. Handbook on metals in clinical and analytical chemistry. New York: Marcel Dekker, 1994:479-494). Therefore, a 'Hg intoxication', that should be treated, was not diagnosed by the Hg concentration in the bio-monitors alone, but by a balanced combination of these Hg values and the medical score sum. In principle, this means the higher the Hg concentration in the bio-monitors, the lower the number of characteristic adverse effects are required for a positive diagnosis. By this method, 0% of the controls, 38% downstream, 27% from Mt. Diwata, non-occupational exposed and 71.6% of the workers were classified as Hg intoxicated. A reduction of the external Hg burden on Mt. Diwata is urgently recommended. An attempt to treat the intoxicated participants with the chelating agent dimercaptopropanesulfonic acid (DMPS) is planned.
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PMID:The Mt. Diwata study on the Philippines 1999--assessing mercury intoxication of the population by small scale gold mining. 1503 60


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