Time Course of Inhibition Induced by a Putative Saccadic Suppression Circuit in the Dorsal Lateral Geniculate Nucleus of the Rabbit

Psychological studies have revealed that a visual suppression occurs during the saccadic eye movements to maintain the stable visual image. This visual suppression is named saccadic suppression. A typical saccadic suppression precedes the saccadic eye movements by 30–60 ms, lasts 120–180 ms, and is followed by a 100–150-ms facilitation. Recently, we have revealed an inhibitory circuit connecting the deep layers of the superior colliculus (SC) to the dorsal lateral geniculate nucleus (LGN), via the central lateral nucleus in the thalamus (CL) and thalamic reticular nucleus (TRN). We speculated that this inhibitory circuit might mediate saccadic suppression in the rabbit. In the present study, we used intracellular recording technique to further examine the synaptic and intrinsic responses of CL cells, TRN cells, and LGN cells to the activation of this inhibitory circuit. We found that the stimulation of the deeper layers of the SC induced a fast excitation postsynaptic potential (EPSP) in CL cells, followed by a robust EPSP in TRN cells and a prolonged inhibitory postsynaptic potential (IPSP) in LGN cells. The EPSP in TRN cells was always followed by a small inhibitory postsynaptic potential (IPSP). The IPSP in LGN cells lasted about 133 ± 27 ms. Sometimes, a rebound bursting occurred after the IPSP in LGN cells. We also examined whether activation of this inhibitory circuit could suppress the retino-geniculo-cortical pathway. We found that the SC stimulation always suppressed the evoked potential in the visual cortex induced by the stimulation of the optic chiasm. Our results of the inhibitory circuit can induce an inhibition in the LGN and a suppression on the retino-geniculo-cortical pathway. The time courses of the inhibition and suppression were compatible with that of saccadic suppression revealed by psychological and physiological studies. These results support the idea that the inhibitory circuit of SC (deeper layers)-CL-TRN-LGN may mediate the saccadic suppression in the rabbit LGN. Copyright © 1996 Elsevier Science Inc.     

ANAESTHETIC MANAGEMENT OF A 2-MONTH-OLD INFANT FOR LASER RESECTION OF VOCAL CORD GRANULOMA

A 2-month-old infant underwent excision of granulomata of vocalcords with a carbon dioxide laser. High frequency jet ventilationwas given through a surgical metal suction tube during the operation.The anaesthetic technique for the infant and the problems ofthe use of carbon dioxide laser in laryngeal surgery are discussed.     

Ursodeoxycholic acid in the treatment of primary biliary cirrhosis: A short-term, randomized, double-blind controlled, cross-over study with long-term follow up

Abstract In order to evaluate the efficacy of ursodeoxycholic acid (UDCA) in the treatment of Chinese patients with primary biliary cirrhosis, a short-term, randomized, double-blind controlled, cross-over study was done with long-term follow up. In the first part of the study, 12 patients were randomly chosen to receive either UDCA 600 mg/day for 3 months followed by a placebo for 3 months or a placebo for 3 months followed by UDCA for 3 months. The clinical symptoms of pruritus improved when the patients were receiving UDCA but became worse when receiving a placebo. Mean serum levels of alkaline phosphatase (ALPase), γ-glutamyl transferase (γ-GT), total bilirubin, cholesterol, alanine aminotransferase (ALT) and aspartate aminotransferase all decreased below the baseline values when receiving UDCA treatment and all increased above the baseline values when receiving the placebo. The difference was statistically significant. In the second part of the study, 19 patients received long-term UDCA treatment (mean 20 months). The clinical symptoms of pruritus improved in 90% of the pruritic patients. Serum levels of ALPase, γ-GT and ALT fell significantly from the pretreatment values 6, 12 and from the mean 20 months after UDCA treatment. Serum levels of total bilirubin fell significantly 6 and 12 months after UDCA treatment but did not reach statistical significance at the last follow up. No patient lost antimitochondrial antibody and elevated immunoglobulin levels did not improve significantly, but the Mayo clinical risk score improved significantly after long-term UDCA treatment. Treatment failure was noted in three patients: two patients in the histologic stage IV with clinical overt jaundice died of complications 4 and 5 months after UDCA treatment, respectively; another patient underwent a liver transplantation 1 year after the UDCA treatment due to progressive jaundice. No severe adverse reaction was noted during UDCA treatment, only one patient suffered from a mild allergic reaction. In conclusion, UDCA is safe and effective in the treatment of Chinese PBC patients in stages I—III.     

Regressed Subungual Melanoma Simulating Cellular Blue Nevus: Managed with Sentinel Lymph Node Biopsy

BACKGROUND: Subungual melanoma, a not uncommon presentation of cutaneous melanoma in Asian populations, is easily overlooked as benign and thus is improperly treated. OBJECTIVE: To present two cases with clinical suspicion of subungual melanoma. Skin biopsies failed to demonstrate the diagnostic features of malignancy. METHODS: Lymphoscintigraphy and sentinel lymph node (SLN) biopsies were performed to determine regional lymph node status. RESULTS: Both hematoxylin-eosin and HMB45 staining revealed melanoma cells in the SLN of the patient. The second patient's SLN was negative for malignant cells, but her excised primary lesion showed extensive regressed melanoma. CONCLUSION: Regression phenomena are not uncommon for subungual melanoma. An extention biopsy techniques are useful for determining nodal basin status in regressed subungual melanoma.     

伽玛刀治疗原发性三叉神经痛22例疗效分析

目的 探讨伽民治疗原发性三叉神经痛的疗效，疗效与剂量关系。方法 采用OUR－XGD／B型旋转式伽玛刀Leksell-G型立体定位仪，1.0TMRI扫描定位，Gamma-TPS规划系统，在痛侧三叉神经根部，用4mm准直器，布1－2靶点中心，中心剂量为80－100Gy。结果 22例获得随访3.5-32.5个月（平均19.6个月）。整剂量组平均缓解时间115天，90－100Gy剂量组疼痛缓解时间明显缩短（平均26天），中心剂量90－100Gy组与其他剂量组不良反应没有明显差异（P＜0.05)。59.1%患者疼痛完全缓解，22.7%患者疼痛缓解＞90％，9.1%患者疼痛缓解＞50％，总有效率（90.9%)。结论 伽玛刀治疗原发性三叉神经痛是一种安全有效的方法，治疗中心剂量一般考虑为90－100Gy。     

Evaluation of pretest clinical score (4 T''s) for the diagnosis of heparin-induced thrombocytopenia in two clinical settings

BACKGROUND: Heparin-induced thrombocytopenia (HIT) is a prothrombotic adverse drug reaction caused by heparin. As thrombocytopenia is common in hospitalized patients receiving heparin, it would be useful to have a clinical scoring system that could differentiate patients with HIT from those with other reasons for thrombocytopenia. AIM: To compare prospectively the diagnostic utility of a clinical score for HIT in two different clinical settings. METHODS: The pretest clinical scoring system, the '4 T's', was used to classify 100 consecutive patients referred for possible HIT in one hospital (Hamilton General Hospital, HGH) into high, intermediate, and low probability groups. This system was also used to classify likewise 236 patients by clinicians in Germany referring blood for diagnostic testing for HIT in Greifswald (GW). The clinical scores were correlated with the results of laboratory testing for HIT antibodies using the serologic criteria for HIT with high diagnostic specificity. RESULTS: In both centers, patients with low scores were unlikely to test positive for HIT antibodies [HGH: 1/64 (1.6%), GW: 0/55 (0%)]. Patients with intermediate [HGH: 8/28 (28.6%), GW: 11/139 (7.9%)] or high scores [HGH: 8/8 (100%), GW: 9/42 (21.4%)] were more likely to test positive for clinically significant HIT antibodies. The positive predictive value of an intermediate or high clinical score for clinically significant HIT antibodies was higher at one center (HGH). CONCLUSIONS: A low pretest clinical score for HIT seems to be suitable for ruling out HIT in most situations (high-negative predictive value). The implications of an intermediate or high score vary in different clinical settings.     

Delayed administration may improve entacapone effects in parkinsonian patients non-responding to the drug

BACKGROUND: Entacapone is a COMT inhibitor used in Parkinson's disease (PD) patients, as an adjunctive therapy to L-dopa in order to prolong its bioavailability and thus its clinical effect. However, previous studies reported entacapone-induced L-dopa to have lower C(max) and delayed t(max) values, coupled with a delayed onset of the clinical effect, possibly suggesting an interference between the two drugs. The aim of our study was to evaluate whether a delayed entacapone administration in association with standard L-dopa/carbidopa, may in some subjects improve the entacapone effects on L-dopa AUC and thus on the clinical 'on time' duration. METHODS: Twenty-eight idiopathic advanced PD patients were blindly evaluated in three different test days, following administration of carbidopa/L-dopa or carbidopa/L-dopa plus co-administered entacapone or plus entacapone administered with 30 min of delay. RESULTS: The AUC, the 'on time' and UPDRS score of the whole group were improved by both modalities of entacapone administration. An ex post analysis showed that the delayed entacapone administration produced a significant improvement in a subgroup of 10 non-responding patients to the co-administration. CONCLUSION: We suggest that the delayed administration should be attempted in the subjects not improved by entacapone co-administration.     

Atrial Dissociation After Atrial Compartment Operation for Chronic Atrial Fibrillation in Mitral Valve Disease

Atrial dissociation with segmental atrial arrhythmia is an interesting electrophysiological phenomenon. It was rarely reported before to be caused by anatomical exit block after cardiac surgery. We report the case of a 28-year-old patient who developed atrial dissociation after a surgical method for correcting atrial fibrillation—atrial compartment operation. The segmental atrial flutter was first found by Doppler echocardiography and proved later by detailed intracardiac mapping.     

Effects of routinely given pethidine during labour on infants' developing breastfeeding behaviour. Effects of dose-delivery time interval and various concentrations of pethidine/norpethidine in cord plasma

A standard dose of 100 mg of pethidine was given im to 13 healthy primiparae during labour. The aim of the study was to investigate whether developing breastfeeding behaviour in the newborn infant was associated with the dose-delivery time interval (DDI) or with the plasma concentration of pethidine and norpethidine in mixed cord blood at birth. The DDI was found to be unevenly distributed with no pethidine exposures in the time interval 5.4-8h. The material was therefore divided into a "short DDI" group (1.1–5.3h) and a "long DDI" group (8.1–9.9h). The infants in the "short DDI" group had a depressed sucking behaviour in 15–45 min of observation and a delayed initiation of lip and mouth movements when compared with the infants in the "long DDI" group. Six of the thirteen infants did not suck their mothers' breasts during the observation period. These infants had higher median plasma concentrations of pethidine at birth than the seven infants who did start sucking. No differences were found between the plasma levels of norpethidine and the behaviour. It was concluded that 100mg of pethidine im as an analgesic given under routine conditions may have unfavourable effects on infants' developing breastfeeding behaviour if the DDI is short.