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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Isometric twitch responses of single motor units in snake costocutaneous muscle have been recorded before and after conditioning tetanic stimulation. 2. Most units showed post-tetanic potentiation of twitch tension, associated with increased maximal rate of rise of twitch tension, and in some cases also associated with prolongation of twitch contraction time. A few units showed a short phase of actual depression of the post-tetanic twich responses, followed by potentiation. 3. The time course and magnitude of post-tetanic changes of twitch tension and maximal rate of rise of tension could be described by the sum of three processes which are assumed to be maximal close to the end of the conditioning tetanus: (i) a rapidly declining potentiation (called here early potentiation, which lasted less than 2 sec) which may have a purely mechanical origin; (ii) a much slower-declining potentiation (called here prolonged potentiation, which lasted up to 15 min); and (iii) a process which lasted up to 60 sec during which twitch potentiation was reduced. The latter process (called here depressed potentiation) was usually apparent as a marked trough in the plots of twitch amplitude versus time after the conditioning tetanus, and occassionally was evident as an actual transient depression of twitch amplitude after the tetanus compared with that before. 4. The effects of the prolonged potentiation and the depressed potentiation on the maximal effect of each process close to the end of the tetanus were extracted by fitting single exponential equations to different portions of the data, using a computer program. 5. Twitch potentiation associated with increased maximal rate of rise of tension seemed to be a separate phenomenon to that associated with prolongation of contraction time, seen when conditioning tetani of higher frequency and numbers of stimuli were employed. The depressed potentiation of twitch tension tended to be partly masked in cases where contraction time was prolonged, but this did not affect the depressed potentiation of maximal rate of rise of tension. 6. The post-tetanic potentiation shown by a unit was related to the contraction time of the unit, in addition to the well known relationship to the initial twitch-tetanus ratio. The depressed potentiation may correlat more closely with the initial twitch-tetanus ratio than with the unit contraction time. 7. The magnitude of maximal depressed potentiation shown by a unit may be directly correlated to that of maximal prolonged potentiation. 8. The time constant of decay for prolonged potentiation of twitch tension tended to be related inversely to unit contraction time and directly to unit size and the maximal value of prolonged potentiation oftwitch tension. The time constant of decay for prolonged potentiation of maximal rate of rise of tension tended to be related to unit size and initial twitch-tetanus ratio, and the time constant of decay for depressed potentiation of rate of rise of tension tended to be related to unit size. 9...
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PMID:Post-tetanic potentiation of twitch motor units in snake costocutaneous muscle. 65 Apr 83

The changes with postnatal age in post-tetanic potentiation (PTP) and fatigue of the inferior oblique muscle have been studied in the cat. PTP of the twitch amplitude increased steadily with age up to 20 weeks after birth. Twitch contraction time (ct) and half relaxation time (hrt) was not significantly changed. The potentiation of the tetanic response also became more prominent with age. The young muscles (10 weeks and below) were slightly more susceptible to fatigue than older muscles, but recovery was rapid in muscles of all ages. Intensive stimulation induced post-tetanic depression of twitch responses in muscles older than 1 week, but none in the muscles of new-born cats. Ct and hrt were greatly prolonged in muscles above six weeks of age. In these muscles, but never in the very youngest, repetitive firing could be observed in response to post-tetanic single nerve stimulation. The results are compared with those obtained in similar experiments on hind-limb muscles by other workers. They further support the idea, raised in a previous paper, that slow eye muscle fibres develop quicker and reach maturity earlier than fast fibres.
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PMID:The postnatal development of the inferior oblique muscle of the cat. II. Effects of repetitive stimulation on isometric tension responses. 67 66

The effects of lithium carbonate on the responses to five neuromuscular blocking agents were evaluated in dogs anesthetized with halothane (1 per cent) and N2O (60 per cent) in O2. Latency (time from first twitch-height depression to maximal blockade), maximal twitch-height depression, and times to return to 50 per cent and 100 per cent control twitch tension were measured before and after intravenous infusion of lithium carbonate (1 mg/kg/min for one hour) during neuromuscular blockades produced by succinylcholine, decamethonium, gallamine, d-tubocurarine, or pancuronium. Lithium prolonged the latencies of neuromuscular blockades produced by 0.1 mg/kg succinylcholine and 0.1 mg/kg decamethonium by 248.1 per cent and 49.0 per cent, respectively, but had no effect on latency produced by 0.02 mg/kg pancuronium. The times for return to 50 per cent of control twitch height were prolonged by 69.5, 40.0, and 120.1 per cent, respectively. Lithium had no effect on latency or duration of blockades produced by 0.15 mg/kg d-tubocurarine and 0.6 mg/kg gallamine, but enhanced maximal twitch-height depressions produced by 0.9 mg/kg gallamine and 0.02 mg/kg pancuronium by 22.9 and 9.9 per cent, respectively. Twitch tensions decreased 5-10 per cent over three hours in three dogs receiving lithium infusion without relaxants. Twitch tension was depressed 0-2 per cent in three dogs after five hours of anesthesia in the absence of lithium or relaxants. Lithium prolonged the time required for neostigmine to reverse neuromuscular blockade produced by pancuronium in two of three dogs from a mean of 60 seconds to 135 seconds.
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PMID:Lithium carbonate and neuromuscular blocking agents. 83 45

The neuromuscular effects of d-tubocurarine (dTc), pacuronium, and succinylcholien (SCh) were studied in 37 unpremedicated adult surgical patients anesthetized with 1.25 MAC enflurance in oxygen. The relaxant doses that produced 50 per cent depression of twitch height (ED50) were 1.57, 0.29, and 4.9 mg/m2 for dTc, pancuronium, and SCh, respectively. These doses are approximately 3.1, 1.7, and 1.0 times less than the amount of dTc, pancuronium, and SCh required to produce 50 per cent depression of twitch height during halothane anesthesia but are the same as ED50 values during isoflurane anesthesia. In eight additional unpremedicated patients anesthesia was maintained at 0.71 MAC enflurane in oxygen (five patients) or 1.67 MAC enflurane in oxygen (three patients). Twitch depression following dTc, 1.5 mg/m2, was related directly to alveolar enflurane concentration. Ability to sustain tetanus decreased progressively with increasing tetanic frequencies and decreased with increasing alveolar enflurane concentrations. The authors concluded that smaller doses of dTc and pancuronium are needed for adequate relaxation during enflurane anesthesia than during equi-MAC halothane anesthesia, and that higher alveolar enflurane concentrations reduce the dose of dTc necessary to produce a given amount of paralysis. Also, neuromuscular effects of enflurane in combination with dTc or pancuronium are not significantly different from those seen suring equi-MAC isoflurane anesthesia.
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PMID:Neuromuscular effects of enflurane, alone and combined with d-Tubocurarine, pancuronium, and succinylcholine, in man. 111 66

The cardiopulmonary effects of 2 new inhalant anesthetics, enflurane and isoflurane, were studied in nonsedated, previously instrumented, awake dogs. Base line values were determined, and anesthesia was induced and maintained with the drug being studied. Enflurane depressed cardiopulmonary function to a greater extent than isoflurane. The depression of cardiopulmonary function from both agents increased with increasing depth of anesthesia. Enflurance produced muslce twitching, but isoflurane did not.
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PMID:Cardiopulmonary effects of enflurane and isoflurane in the dog. 125 10

The basis for the comparative toxicity to parasitic nematodes and their mammalian hosts of the anthelmintics levamisole, pyrantel, and several related analogs on somatic nicotinic cholinergic transmission was examined. Measurements of muscle contractility and membrane potential were made using the isolated hemidiaphragm preparation of the rat and isolated axial muscle segments from the gastrointestinal nematode Haemonchus contortus. Pyrantel caused a dose- and time-dependent reduction of nerve-evoked twitches in the rat diaphragm. These effects were exacerbated by increasing the frequency of phrenic nerve stimulation from 0.5 to 50 Hz. Levamisole was less potent and the onset of its effects slower than pyrantel. Neither drug significantly affected twitches evoked from d-tubocurarine-blocked preparations following direct stimulation of the diaphragm. Twitch depression was reversed by washing, but not by application of physostigmine. In H. contortus, both drugs stimulated a spastic contraction and sustained paralysis in the concentration range of 1-10 microM, mimicking the action of nicotine. Neither nicotinic nor muscarinic antagonists blocked these responses. Moreover, neither nicotinic antagonists nor muscarinic agonists or antagonists had any independent effect on contractility of the parasite muscle segments. The blocking actions of levamisole and pyrantel on H. contortus axial muscle were associated with membrane depolarization at the muscle. In the rat-isolated hemidiaphragm, pyrantel, but not levamisole, depolarized end-plate regions of muscle fibers. d-Tubocurarine blocked the depolarizing action of pyrantel but not levamisole on rat-isolated hemidiaphragm. In axial muscle fibers of H. contortus, d-tubocurarine did not block the depolarizing actions of pyrantel, levamisole, or nicotine. 3-Bromo and 3-amino derivatives of levamisole were equipotent with and mimicked the actions of the parent compound on H. contortus axial muscle contractility. In the rat preparation, the 3-bromo derivative was more potent than levamisole or 3-amino-levamisole. 3-Amino-levamisole, but not 3-bromo-levamisole, depolarized muscle end-plate membrane in the rat diaphragm. Results of the present study are consistent with the following conclusions: (a) both levamisole and pyrantel block contractility of nematode axial muscle by causing sustained depolarization of the muscle membrane; (b) both drugs block neuromuscular transmission at the mammalian neuromuscular junction but their mechanisms appear to differ; (c) levamisole and pyrantel are more potent blockers of neuromuscular transmission in H. contortus than in the rat. These results suggest that potentially important pharmacological differences exist between nematode and mammalian somatic nicotinic receptors.
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PMID:Comparative neuromuscular blocking actions of levamisole and pyrantel-type anthelmintics on rat and gastrointestinal nematode somatic muscle. 131 Jan 65

The clinical features and management of nine cases of mushroom poisoning due to Amanita pantherina (eight cases) and Amanita muscaria (one case) admitted to a children's hospital are described. Most ingestions were in the toddler age group with males being more frequently involved. Symptoms occurred between 30-180 min with the onset of central nervous system depression, ataxia, waxing and waning obtundation, hallucinations, intermittent hysteria or hyperkinetic behavior. Vomiting was rare. Seizures or myoclonic twitching occurred in 4/9 patients, but was controlled with standard anticonvulsant therapy. No other anticholinergic or cholinergic signs were prominent. Recovery was rapid and complete in all patients.
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PMID:Mushroom poisoning in infants and children: the Amanita pantherina/muscaria group. 134 20

We have used overcrowding stress to study the pathogenesis of depression and the action of antidepressant drugs. In the present study, the influence of overcrowding on behavior was assessed by the forced swimming test. All the stressed rats revealed highly characteristic head twitching movement, which was not inhibited by repeated administration of diazepam and haloperidol, but was markedly suppressed by repeated administration of desipramine and mianserine. A significant positive correlation in the number of twitching episodes in each stressed rat between the first and second forced swimming test was seen. These findings support the use of overcrowding of rats as a stressor in the animal depression model because it fulfills the criteria of the model; face validity, construct validity and predictive validity. We propose the adoption of "swimming head twitching" as a new marker in the animal model of depression.
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PMID:"Swimming-induced head twitching" in rats in the forced swimming test induced by overcrowding stress: a new marker in the animal model of depression? 147 66

The familial transmission risk of developing bipolar disorder for first=degree relatives of the patient is 1.5-10.2%, however, the risk of any affective primary disorder is 15-20% in such relatives. Pregnancy places additional stress on patients, and physiological changes are particularly acute during postpartum. The risk of abnormalities and teratogenicity from psychotropic drugs is significant: taking of phenothiazines, tricyclic antidepressants, monoamine oxidase inhibitors, benzodiazepines, lithium, valproate, and clonazepam require extreme caution. In 225 pregnancies exposed to lithium in the 1st trimester congenital malformations occurred in 11%. Premature birth and macrosomia may also increase, thus halting lithium well before planned conception with weekly serum monitoring is advised. Recurrence of the illness can be managed by electroconvulsive therapy. About 40% of patients can experience postpartum mania or depression. Taking drugs up to delivery can result in behavioral teratogenesis in the neonate even in the absence of physical malformations. Lithium toxicity causes lethargy, hypotonia, tachycardia, coma, cyanosis, and chronic twitching in the newborn. Breast feeding is discouraged in women taking lithium because of the high rate of transmission to the infant. The stress of parenting can also trigger relapses of the disease. The deleterious effect of a manic or depressive mother on the child's development is manifested in criticism and stressing achievement often leads to low self-esteem. It behooves the psychiatrist to frankly reveal the risks of pregnancy to couples who wish to have a child or to advise about the pregnancy to term so they can make an informed decision.
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PMID:Family planning for women with bipolar disorder. 158 11

A woman in her late 40s with a 5 year history of anxiety was treated with relaxation training and cognitive restructuring. Her anxiety was manifested by facial twitching, hand fidgeting, vocal tremor, loss of self-esteem, and depression. Therapy seemed to reduce motor symptoms and improve her self-esteem, confidence, and mood. Six months after the start of therapy the client was found to have Meige's Disease. Following treatment with botulinum toxin, motor symptoms disappeared. This case highlights the need for psychotherapists to be more aware of neurological and medical problems which may mimic psychological ones.
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PMID:Meige's disease misdiagnosed as anxiety disorder. 180 56


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