Lack of tolerance to nicotine-induced dopamine release in the nucleus accumbens

The extent to which repeated administration produces tolerance to nicotine-induced increases in dopamine transmission in the nucleus accumbens was investigated in rats. In vivo microdialysis was used to sample extracellular dopamine and metabolites after a nicotine challenge (0.35 mg/kg) in (1) naive rats, (2) acutely pretreated rats (1 prior nicotine injection), and (3) chronically pretreated rats (12-15 prior daily nicotine injections, 0.35 mg/kg per injection). Nicotine increased extracellular DA and its metabolites, and these increases were not significantly altered by either acute or chronic prior exposure to the drug. The failure to find evidence of tolerance is compatible with the hypothesis that the mesolimbic dopaminergic system is a substrate for the reinforcing properties of chronically administered nicotine.     

Severe hypoglycorrhachia after subarachnoid hemorrhage. Two cases with spontaneous recovery in adults

We report two patients with severe hypoglycorrhachia after a subarachnoid hemorrhage. They had no obvious meningeal infection, and they spontaneously recovered within a few weeks. Such cases have previously been reported in neonates, but exceptionally in adults. Contrary to detailed cases from the literature, our patients recovered without antibiotics, and hypoglycorrhachia was very severe.     

An antinociceptive profile of kojic amine: an analogue of gamma-aminobutyric acid (GABA)

Kojic amine [2-(aminomethyl)-5-hydroxy-4H-pyran-4-one], an analogue of gamma-aminobutyric acid (GABA), produced dose-related, but short-lived, antinociceptive activity in the 48 degrees C [ED50 = 9.2 (8.2-10.3) mg/kg i.p.] and 55 degrees C [ED50 = 13.8 (12.2-15.7) mg/kg i.p.] hot-plate tests in the mouse. The antinociceptive activity of kojic amine at 48 degrees C was found to be insensitive to bicuculline (1.0 mg/kg i.p.) and picrotoxin (0.5 mg/kg i.p.). At this temperature, antinociception was distinctly separate from the impairment of motor function (measured by a rotorod assay) and was not significantly affected by prior treatment with the cholinergic antagonist, atropine sulfate (10.0 mg/kg i.p.). However, at 55 degrees C, the antinociceptive effect of a large dose (20 mg/kg i.p.) of kojic amine was significantly attenuated by similar pretreatment with atropine sulfate, but not by the peripheral cholinergic antagonist, atropine methylnitrate (10.0 mg/kg i.p.). Kojic amine exhibited no significant interaction with haloperidol (0.5 mg/kg i.p.) at this temperature. In animals made tolerant to morphine, THIP or baclofen, there was analgesic cross-tolerance between kojic amine, morphine and baclofen but not between kojic amine and THIP. It is suggested that kojic amine-induced antinociception is similar to that produced by both THIP and baclofen. Thus, kojic amine represents a unique tool with which to study GABA-ergic antinociceptive processes.     

Cerebral venous thrombosis as a cause of neonatal seizures

Intracranial venous thrombosis has been described in newborns, but there have been no reports of intractable neonatal seizures due to this condition. We report cortical venous sinus thrombosis in two term neonates who presented with seizures in the first 24 hours of life. The diagnosis was made by cranial computed tomography and was confirmed by cerebral angiography. Both patients improved clinically after the intracranial venous thrombosis resolved. These patients demonstrate that intracranial venous thrombosis should be considered in the differential diagnosis of neonatal seizures.     

Studies of the induction and maintenance of long-term graft acceptance by treatment with FK506 in heterotopic cardiac allotransplantation in rats

Immunosuppressive activities of the newly discovered FK506, isolated from Streptomyces tsukubaensis, were examined by using cardiac allotransplantation in the rat, and the mechanisms underlying induction and maintenance of FK506-induced long-term allograft survival were studied. Male rats of WKA (RT1k) and F344 (RT1lvl) strains were used as recipients and donors, respectively, and those of BN (RT1n) strain were used as third-party donors. Treatment with FK506, beginning from the day of allografting for 14, 10, or as few as 4 days, prolonged allograft survival significantly across the major histocompatibility barrier. The minimum doses for prolonging graft survival were 0.1 mg/kg/day by intramuscular treatment and 1.0 mg/kg/day by oral treatment. Treatment with FK506 at a dose of 0.32 mg/kg/day from day 4 until day 10 resulted in all the grafts surviving indefinitely and from days 5 to 10, half the grafts survived indefinitely, suggesting that the agent inhibited ongoing rejection. On the other hand, cyclosporine treatment at a dose of 20 mg/kg/day from day 2 did not prolong graft survival time statistically significantly. Induction of prolonged graft survival was not obtained by pretreatment of the prospective donor or recipient; prolonging effects were observed only when the agent was administered after allografting. Thus, the primary effect of the agent is exerted on responder lymphocytes reacting to the donor antigens in the induction phase of long-term graft acceptance. The mechanisms underlying the maintenance of long-term grafts were analyzed by testing the capacity of lymphocytes or serum of long-term graft-bearing rats to inhibit graft rejection in irradiated grafted hosts. Transfer of 2 x 10(8) lymphocytes from FK506-induced long-term F344 graft-bearing WKA rats resulted in indefinite survival of F344 heart allografts, but it did not prolong survival of third-party BN hearts. Transfer of 2.5 ml serum from long-term graft-bearing rats also prolonged graft survival of F344 hearts, but not BN hearts. These results suggest that donor strain-specific suppressor cells and humoral factor(s) are induced by treatment with FK506 in the presence of allografts, and that they play at least partial roles in the maintenance of long-term allograft acceptance.     

Cardiocirculatory disturbances after surgery of carcinoma of the thoracic esophagus

From 1976 to 1985, 277 cases of carcinoma of the esophagus were resected in the Second Department of Surgery, Tohoku University School of Medicine. Postoperative cardiocirculatory disturbances occurred in 114 cases (41.2%), arrhythmia being the disturbance most frequently observed (86.8%). Low cardiac output syndrome occurred in 8 cases and myocardial infarction occurred in 3 cases. The majority of the cases were treated successfully, but 5 patients died within one month after operation. Causes of death were as follows: myocardial infarction, constrictive pericarditis, cardiac tamponade, non-occlusive mesenteric ischemia and acute cardiac failure. Postoperative arrhythmia occurred mainly up to the third postoperative day. Low cardiac output syndrome occurred just after operation or on the first postoperative day. All cases of myocardial infarction occurred on the first postoperative day. The rate of occurrence of cardiocirculatory disturbances in aged patients (greater than or equal to 70) was significantly higher than other group (less than or equal to 69), (56.7%:38.1%, p less than 0.05). The rate of occurrence of cardiocirculatory disturbances in patients who had a history of hypertension or in patients with abnormal preoperative electrocardiographic findings were relatively higher than those in patients who had no history of hypertension or in patients with no abnormal preoperative electrocardiographic findings. The rate of occurrence of cardiocirculatory disturbances in patients who had undergone total resection of the thoracic esophagus was significantly higher than that in patients who had undergone partial resection of the thoracic esophagus (42.8%:23.8%, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Pressure constant, transurethral resection with the new suprapubic "overflow regulator"

A new suprapubic device that regulates the intravesical pressure automatically during TUR is introduced. This flow controller ensures a constantly low intravesical pressure during TUR. The irrigation fluid constantly flows over into a small open glass jar adjusted to the trocar immediately above the abdominal wall. In this way the pressure is determined by the height of the jar above the bladder, which makes it independent of the irrigation flow. Having constant low pressure conditions between 14 and 18 cm H2O, the bladder wall does not collapse. Thus, the anatomical situation does not change throughout the entire operation, which leads to markedly better overall vision.