Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0027066 (myoclonus)
 4,275 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A 44-year-old man suffered from repeated impairment of consciousness associated with flapping tremor, myoclonus and generalized convulsions, and died in coma 6 months after admission. He had had a psychosomatically underdeveloped childhood, with a propensity for legumes without a family history of the same or a record of consanguinity. On admission, he had disturbed consciousness and emaciation without other physical abnormalities. The EEG revealed diffuse slow waves with occasional appearance of triphasic waves. A high level of serum citrulline (534.7 nmol/ml) was recognized and the assay of urea cycle enzymes in the liver demonstrated decreased argininosuccinate synthetase (ASS) activity (0.062 U/g liver, 7.4% of that in normal liver), although no kinetic abnormality was found. Accordingly he was diagnosed as having type II citrullinemia. In addition, this case could be classified as cluster type of localization of the ASS in the liver by immunohistochemical study. There were characteristic findings concerning his clinical picture and laboratory data, such as a significant correlation between the grade of disturbed consciousness and arterial blood gas pH (r = 0.61, p less than 0.01). However, the blood ammonia level did not always correlate with the severity of disturbed consciousness. Oral treatment with sodium citrate and sodium benzoate was very effective, though transiently, for disturbed consciousness in this case. Pathological findings of the autopsied liver were fatty change and fibrosis. Neuropathologically, characteristic findings were brain edema with cerebellar tonsilar herniation, laminar necrosis with spongy formation in cerebral cortex, and Alzheimer type II glia. The relationship between citrullinemia and other hepatic encephalopathy was also discussed.
 ...
PMID:[An autopsied case of type II citrullinemia--transient effectiveness with either citrate or benzoate to the consciousness disturbance]. 269 30

Stimulus sensitive myoclonus is a prominent symptom of uremia in both man and animals. Intravenous injection of urea into cats had been previously reported to produce spike and sharp wave electrical discharges in the medullary reticular formation which correlated with the myoclonic movements. In the present investigations, intraperitoneal injections of 2 g/kg urea every 15 minutes for 4 injections produced myoclonus in rats accompanied by brain urea concentrations of 6.8 X 10(-2)M, which is sevenfold higher than normal. 10(-2) and 10(-1) M urea significantly reduced 3H-strychnine binding to rat medulla membranes by 30% and 43% respectively. Urea inhibition of 3H-strychnine binding was reversible and binding kinetics revealed that 10(-1)M urea decreased Bmax by 65% with no effect on the affinity. Brain glycine levels did not change after urea injections and urea had no effect on synaptosomal uptake of 3H-glycine. Urea did not alter 3H-GABA, 3H-glutamate and 3H-QNB receptor binding but decreased 3H-diazepam receptor binding in the medulla. Mannitol also reduced 3H-diazepam binding but had no effect on 3H-strychnine binding. Stereotaxic injection of the glycine receptor antagonist, strychnine, into the rat medullary reticular formation produced myoclonus, whereas Ro 15-1788, a benzodiazepine antagonist, had no effect. Urea may produce myoclonus by blockade of glycine receptors in the medullary reticular formation.
 ...
PMID:Urea-induced myoclonus: medullary glycine antagonism as mechanism of action. 298 63

Dementia--a syndrome of acquired intellectual deterioration--is an etiologically non-specific condition which is permanent, progressive, or reversible. In the evaluation of demented patients, a careful exposure history will determine the possible role of drugs, metals, or toxins. The physical examination may reveal focal deficits in cases of intracranial mass lesions and spasticity or ataxia of the lower limbs if hydrocephalus is present. Coexistance of dementia and peripheral neuropathy usually indicates a toxic or metabolic disorder. Asterixis, myoclonus, and postural tremor are common in toxic-metabolic dementias, while resting tremor, choreoathetosis, and rigidity occur in progressive extrapyramidal disorders. EEG is focally abnormal in cases of cerebral mass lesions and exhibits generalized slowing in toxic-metabolic encephalopathies. CT will aid in the identification of hydrocephalus, subdural hematomas, and intracranial mass lesions. A thorough laboratory evaluation including complete blood count, erythrocyte sedimentation rate, electrolytes, blood urea nitrogen and blood sugar, liver and thyroid tests, calcium and phosphorus levels, B12 and folate levels, serum copper and ceruloplasmin, VDRL, chest X-ray, electrocardiogram, and lumbar puncture may demonstrate treatable disorders that are adversely affecting intellectual function. Elderly individuals are particularly susceptible to the effects of toxic or metabolic disorders, and a mild dementia might be exaggerated by relatively minor fluctuations in metabolic status. Treatable causes of dementia should be considered in all demented patients.
 ...
PMID:[Treatable dementia syndromes]. 358 48

Two siblings with hyperornithinemia, hyperammonemia, and homocitrullinuria are reported. The clinical picture included protein intolerance, mental retardation, seizures, and stuporous episodes. One patient had cerebellar ataxia, myoclonus, convulsive seizure, and muscular weakness in both legs. Isolated liver mitochondria in the patient revealed that ornithine transport and citrulline synthesis were decreased, but urea cycle enzymes and ornithine aminotransferase were normal. Ornithine metabolism was decreased in cultured skin fibroblasts.
 ...
PMID:Hyperornithinemia, hyperammonemia, and homocitrullinuria: case report and biochemical study. 367 Jun 19

Uremia in humans can cause spontaneous and stimulus-sensitive myoclonus that responds to clonazepam. Uremic myoclonus in humans resembles the reticular reflex form of postanoxic action myoclonus. Previous investigations have established that urea infusions in the cat can produce spontaneous and stimulus-sensitive myoclonus. This has been shown, electrophysiologically, to arise in the brainstem medullary reticular formation, and it does not require forebrain structures. Our own studies in the rat have shown that urea infusions also produce spontaneous and stimulus-sensitive myoclonus. Electrophysiologically, this resembles human reticular reflex myoclonus. It can be reduced by clonazepam. The myoclonus produced by urea infusions in the rat progresses very rapidly into uncontrollable tonic-clonic convulsions. Although the urea model in the rat mimics some forms of human myoclonus that arise in the brainstem, it is not suitable as a routine animal model for pharmacological investigations.
 ...
PMID:Urea-induced stimulus-sensitive myoclonus in the rat. 394 17

Dementia, a syndrome of acquired intellectual deterioration, is an etiologically nonspecific condition that can be permanent or reversible. When evaluating demented patients, a careful exposure history will determine the possible role of drugs, metals, or toxins. Physical examination may reveal focal deficits in cases of intracranial mass lesions and spasticity or ataxia of the lower limbs if hydrocephalus is present. Coexistence of dementia and a peripheral neuropathy usually indicates the existence of a toxic or metabolic disorder. Depressed mood, sleep disturbance, anorexia, impotence, constipation, and psychomotor retardation indicate the presence of a depressive syndrome. Asterixis, myoclonus, and postural tremor are common in toxic-metabolic dementias, whereas resting tremor, choreoathetosis, or rigidity occur in progressive extrapyramidal disorder. EEG is focally abnormal in cases of cerebral mass lesions and shows generalized slowing in toxic-metabolic encephalopathies. CT will aid in the identification of hydrocephalus, subdural hematomas, and intracranial mass lesions. A thorough laboratory evaluation including complete blood count, erythrocyte sedimentation rate, electrolytes, blood urea nitrogen and blood sugar, liver and thyroid function tests, serum calcium and phosphorus levels, B12 and folate levels, serum copper and ceruloplasmin, VDRL, chest X-ray, electrocardiogram, and lumbar puncture may demonstrate treatable disorders that are adversely affecting intellectual function. Elderly individuals are particularly susceptible to the effects of toxic or metabolic disorders, and a mild dementia may be exaggerated by relatively minor fluctuations in metabolic status. Treatable causes of dementia should be sought in all demented patients.
 ...
PMID:Treatable dementias. 635 58

The active morphine metabolite, morphine-6-glucuronide (M-6-G), may contribute to both the analgesia and the adverse effects observed during morphine (MOR) therapy. To evaluate the relationship between M-6-G and adverse effects, we measured steady-state plasma concentrations of MOR and M-6-G and concurrently noted the presence or absence of moderate to severe cognitive impairment or myoclonus in 109 cancer patients who were receiving either oral (n = 71) or parenteral (n = 38) morphine. MOR and M-6-G plasma concentrations were determined by HPLC with electrochemical detection. The presence of cognitive impairment or myoclonus was analyzed in relation to molar M-6-G/MOR ratio, age, morphine dose, the use of other centrally acting drugs, renal function (blood urea nitrogen (BUN) and serum creatinine), hepatic function (serum bilirubin, serum glutamic oxalacetic transaminase (SGOT), and alkaline phosphotase) and serum lactate dehydrogenase (LDH). The patient population consisted of 60 women and 49 men. The mean age was 51.5 years (range: 10-85 years). The mean morphine dose (total dose-prior 48 h) was 486 mg (range: 40-4800 mg) for the oral group and 931 mg (range: (10-9062 mg) for the parenteral group. The mean molar M-6-G/MOR ratios were 6.1 (SD: 18.2; range: 0.01-153.3) for the oral treatment group and 2.7 (SD: 4.16; range: 0.05-23.8) for the parenteral treatment group. Overall, the M-6-G/MOR ratio demonstrated a moderate but significant correlation with BUN (r = 0.4; P < 0.001) and creatinine (r = 0.45; P < 0.001) levels, but not with the other clinical variables examined.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Morphine-6-glucuronide concentrations and opioid-related side effects: a survey in cancer patients. 764 48

Catechol- and urea-induced myoclonus models in the rat were electrophysiologically compared to clarify pathophysiological differences. Catechol-induced myoclonus had various similarities with cortical reflex myoclonus in that there were electroencephalogram (EEG) discharges prior to myoclonic discharges, a spread of myoclonic discharges from the rostral to the caudal site, and a high amplitude somatosensory evoked potential (SEP). In urea-induced myoclonus, there were no EEG discharges related to myoclonic discharges and no enlarged SEP components as in reticular reflex myoclonus. Catechol-induced myoclonus had two evoked EMG responses of the biceps femoris at mean onsets of 8.0(C1) and 13.4 (C2) ms, and urea-induced myoclonus had a response (U1) at the mean onset of 10.2 ms. A study of the effects of various lesions in the central nervous system on these evoked EMG responses suggests that C1 is a monosynaptic spinal reflex. C2 which disappeared when the bilateral sensorimotor cortex for the hind limb had been resected and the lesion cooled is generated by the deep cerebral structures, such as the thalamus or basal ganglia, and U1 originates in the brain stem reticular formation. These results imply definitive differences of the pathophysiological mechanisms between catechol- and urea-induced myoclonus.
 ...
PMID:Electrophysiological comparison between catechol- and urea-induced myoclonus models in the rat. 840 42

Piracetam [2-oxo-1-pyrrolidineacetamide], a cyclic GABA, has been used in Europe for the treatment of patients with cognitive disorders. We investigated the effect of piracetam on urea-induced myoclonus in rats. Myoclonus was induced by intraperitoneal injection of 4.5 g/kg urea, and was recorded with EMG and video apparatus. The incidence of induced myoclonus decreased significantly by intraperitoneal injection of 300 mg/kg piracetam and oral administration of 0.3-10 mg/kg clonazepam. Furthermore, the combined application of 100 mg/kg piracetam and 0.03-0.1 mg/kg clonazepam was effective in ameliorating the myoclonus, although separate administrations were not effective. These findings suggest that piracetam is an effective drug for treating myoclonus, particularly when it is used in combination with clonazepam.
 ...
PMID:[Effect of piracetam on urea-induced myoclonus in rats]. 1106 61

Myoclonus is defined as shock-like, brief involuntary abnormal movements in muscle jerking caused by external stimuli; and it arises from progressive myoclonus epilepsy, post-anoxic encephalopathy and Alzheimer's disease, causing disabling symptoms. It is a rare syndrome but very difficult to control. Piracetam (2-oxo-1-pyrrolidineacetamide, Myocalm) was developed more than 30 years ago as a cyclic derivative of gamma-aminobutyric acid (GABA); it has been used in European countries for the treatment of memory loss and other cognitive defects in patients. Some reports have suggested that piracetam has anti-myoclonus activities, but the mechanisms of myoclonus are not well-identified, and thus there have been few preclinical studies on piracetam for the treatment of myoclonus. We investigated the effect of piracetam and clonazepam, an anti-epileptic drug, on high dosage urea-induced myoclonus using an electromyogram in rats. The incidence of myoclonus induced by urea 4.5 g/kg (i.p.) was significantly reduced by piracetam at 300 mg/kg (i.p.) and by clonazepam at 0.3 mg/kg (p.o.). The coadministration of piracetam 100 mg/kg (i.p.) and clonazepam at 0.03-0.1 mg/kg (p.o.) significantly reduced the incidence of myoclonus, although separate administration was not effective. After oral administration of piracetam, it is rapidly and completely absorbed and excreted almost unchanged in the urine; however, it does show a little binding to human serum protein. Repeated oral administration of piracetam for 7 days in phase-I trials did not show any accumulation of the drug. In the placebo-controlled double-blind crossover trial of piracetam conducted in the UK, there was a significant improvement in cortical myoclonus. In phase-II trials, piracetam inhibited myoclonus and showed an improvement in the quality of life (QOL) of the patients. These results show that piracetam has a beneficial use in clinics for severe myoclonus patients when it is combined with anti-epileptic drugs, demonstrating an improvement in the myoclonus and QOL of patients.
 ...
PMID:[A pharmacological profile of piracetam (Myocalm), a drug for myoclonus]. 1108 17


1 2 Next >>