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Biomedical subjects

G Benedek

Publications and source records attributed to G Benedek.

160 records · Page 9Linked to original sources
PubMedDate not supplied

Data on the role of the frontal cortex in vegetative behavior.

A homeostatic conditional reflex (CR) was elaborated to the effect of repeated inhalations in rats of a gas mixture containing 8 percent oxygen. The effect of the conditional response was opposite to that of the unconditional one. After ablation of the frontal cortex, the conditional reaction disappeared. The repeated administration of 40 mg/kg of histamine resulted in a tolerance to the temperature lowering effect of histamine similar to the habituation. An injection of distilled water brought about dishabituation. Tolerance was not influenced by the ablation of the frontal cortex, but the dishabituating effect of distilled water was absent.

Adaptation, Physiological↗
PubMedDate not supplied

Cholecystokinin interferes with the thermoregulatory effect of exogenous and endogenous opioids.

Intraperitoneal (ip) injection of cholecystokinin octapeptide sulfate ester (CCK; 5, 10 and 50 micrograms/kg) reduced the hypothermic response to 8 mg/kg and 32 mg/kg systemic morphine in restrained and freely moving rats, respectively. The hyperthermia elicited by a subcutaneous (sc) injection of 8 mg/kg morphine to freely moving rats was not diminished by CCK pretreatment. CCK (5 micrograms/kp ip) completely prevented the restraint stress-induced hyperthermia. Naloxone (1 mg/gk sc) was effective in antagonizing both the hyperthermic and the hypothermic effects of morphine and the stress-induced emotional hyperthermia. These results support the hypothesis that CCK may contribute to regulation of the endogenous opioid system.

Animals↗
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Effects of acute and chronic treatment with trazodone, an antidepressant, on the sleep-wake activity in rats.

Rats were treated with trazodone (2.5 or 10 mg kg-1) twice a day (at light and dark onset) for 11 days, after chronic injection of physiological saline. The sleep-wake activity was recorded for 24 h on the baseline day (saline), on trazodone days 1, 5 and 11, and also on day 12, when physiological saline was injected again (withdrawal day). Trazodone administration increased non-REM sleep. The enhancement of non-REM sleep was dose-related and more pronounced during the dark cycle. The promotion of non-REM sleep was enhanced during the chronic treatment. There were no consistent changes in REM sleep. Spectral analysis of the EEG revealed an increase in slow-wave activity after administration of the high dose (10 mg kg-1) of the drug. It is concluded that trazodone, a clinically effective antidepressant, has a non-REM sleep-promoting effect. It is speculated that the promotion of sleep by trazodone may be mediated by serotonergic mechanisms.

Analysis of Variance↗
PubMedDate not supplied

Effect of late surgery for acquired esotropia on visual evoked potential.

PURPOSE: To asses the effect of strabismus surgery on visual evoked potential (VEP) amplitude after age 5 years in children with acquired esotropia. METHODS: Visual evoked potentials to binocular and monocular pattern reversal stimulation were recorded in 10 children aged 5 to 6 years before and 3 months after surgical correction of their esotropia. Visual function (fusion) was tested by synoptophore after strabismus surgery. Electrophysiological and clinical data were correlated following surgical intervention. RESULTS: A significant increase in pattern VEP amplitudes was noted following strabismus surgery. Visual evoked potential changes were most prominent on binocular stimulation. Binocular fusion showed similarly significant improvement after intervention. Postoperative VEP data, however, were not consistently correlated with functional improvement. CONCLUSION: Surgical intervention in esotropia, even if performed years beyond the end of the classical critical period, can have a strong effect on binocular VEPs and a beneficial effect on the development of binocular fusion.

Child↗
PubMedDate not supplied

Biliary decompression in the treatment of acute pancreatitis.

The etiology and treatment of acute pancreatitis are discussed. The two main principles are conservative and surgical treatment. Biliary decompression was chosen as an elective method in the surgical treatment of acute pancreatitis, if signs of bile stasis and tension of the common bile duct could be seen. Peritoneal or peripancreatic dialysis were also applied. Five patients were treated in this way; according to literature and our experience it is a good, short and curative intervention for the treatment of acute pancreatitis.

Acute Disease↗
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Age-variant and age-invariant rhythmicities in the cortical and hippocampal electrical activities of neonatal rats.

The neocortical and hippocampal electrical activities were studied in 8, 15, 22, and 29-day-old rats. Segments of EEG recorded for 4 hours were analyzed by means of fast Fourier transformation. The sleep-wake activity stages were determined. The developments in the neocortical and hippocampal EEG activities were characterized by the gradual appearance of adult-like EEG waves and a shift towards higher frequencies in the theta wave range of the hippocampal electrical activity. The power value in the theta range, however, exhibited age-invariant rhythmicities with cycle lengths of about 9.5-11 and 16-22 min. The manifestation of such an age-invariant rhythm can be interpreted as an electrical manifestation of the rest-activity cycle originally described by KLEITMAN25.

Activity Cycles↗
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Drugs acting at calcium channels can influence the hypnotic-anesthetic effect of dexmedetomidine.

The effects of chronic administration of the calcium channel antagonist verapamil on the anesthetic effects of a novel specific alpha 2-receptor agonist (dexmedetomidine) were studied in rats. It is presumed that this agonist acts on both pre- and postsynaptic alpha 2-adrenoceptors. To determine whether the central postsynaptic receptors are involved in the anesthetic interactions between these drugs, rats were treated with DSP-4 to deplete endogenous norepinephrine. Loss of the righting reflex was used to determine the presence of anesthesia and the duration of hypnosis. Chronic treatment with verapamil (1 or 5 mg/kg) significantly increased the duration of the hypnotic-anesthetic effect of dexmedetomidine. Neither acute treatment with verapamil nor the calcium channel agonist BAY K 8644 (0.5 or 1 mg/kg) influenced the dexmedetomidine-induced hypnosis after DSP-4 treatment. The results seem to support the idea that the hypnotic action of dexmedetomidine can be affected via modulation of the transmembraneous calcium movement in the central nervous system. Further, the data on catecholamine-depleted rats with DSP-4 suggest that the interactions between verapamil and dexmedetomidine may be mediated through presynaptic or homoreceptors on noradrenergic neurons.

Adrenergic alpha-Agonists↗
PubMedDate not supplied

The importance of pulmonary complications as a cause of death in surgical patients.

The authors have retrospectively reviewed 390 autopsy reports from their surgical clinic, to establish the frequency of chronic and acute lung complications in surgical patients. The retrospective analysis revealed that pneumonia was the most frequent acute pulmonary complication among patients who died in the surgical department. In postoperative cases, pneumonia contributed to or was responsible for 65% of all deaths.

Bronchitis↗
PubMedDate not supplied

Effects of elevated ambient temperatures on the sleep-waking activity of rats with impaired warm reception.

The sleep-waking activities of intact and of capsaicin-desensitized rats (animals with damaged peripheral and central warm receptors) were studied at room temperature and at the warm ambient temperatures of 32 and 34 degrees C. At 32 degrees C, the time spent in sleep increased significantly in the desensitized animals, while a decrease in the amount of deep slow wave sleep was found in the controls. At 34 degrees C, the amount of the sleep-waking stages returned to the levels observed at room temperature in the desensitized rats. A further decrease in sleep and a significantly increased wakefulness was found in the controls. At both warm ambient temperatures, the body temperature of the desensitized rats was significantly higher than that of the controls. We suggest that warm environments exert a dual effect on the sleep-waking activity. The activating effect abolished by desensitization seems to be in connection with capsaicin-sensitive thermoreceptors, while the deactivation brought about by heat is not influenced by capsaicin.

Animals↗