赛庚啶对大鼠心肌细胞膜[3H]-d-cis-硫氮卓酮结合部位的影响

苯并噻嗪类钙通道阻滞剂[³H]-d-cis-硫氮酮能以一种特异和可饱和的方式与离体大鼠心肌细胞膜结合,其K_D值和B_max分别为84nmol·L^-1和0.279pmol·mgprotein^-1。非标记的硫氮酮和赛庚啶均能完全抑制这种结合,其Ki值分别为102nmolL^-1和5.5umol·L^-1。上述结果证实在大鼠心肌细胞膜上也存有[³H]-硫氮酮受体,同时还提示赛马庚啶对心肌细胞膜的钙通道阻滞作用可能与作用于心肌细胞膜[³H]硫氮酮受体有关。     

重症急性胰腺炎患者早期胃内pH值变化的临床意义

目的探讨SAP患者SIRS期胃内pH值变化的临床意义及质子泵抑制剂(PPI)对其的影响。方法对2005年1月至2006年11月间,发病时间≤48h的108例SAP患者,采用试纸法检测胃液pH值变化,观测SAP患者人院时及入院后72h平均胃内pH值及pH值>4、>6的时点数变化,并与APACHEⅡ评分及上消化道出血进行比较。将入院时pH值≤4的74例患者分为PPI持续(A组)和间断(B组)静脉输注两组,观察其胃内pH值的变化及与上消化道出血的关系。结果108例患者入院时平均胃内pH值与APACHEⅡ评分呈负相关(r=-0.433,P<0.05)。pH值≤4与>4的患者分别占68.52%与31.48%.上消化道出血的患者分别有12例与1例.差异显著(x~2=3.8774,P= 0.0489)。应用PPI后0～24h,A、B组平均胃内pH值分别为5.24±0.83与4.79±0.89,24～48h时分别为6.21±1.45与5.56±1.22,差异显著(t=2.2067、2.0888,P=0.0305、0.0403),而48～72h时分别为6.42±1.18、5.98±1.05,差异无意义(t=1.6884,P=0.0957)。72h内,A、B组胃内pH值>4的时点数分别为29.22±2.38、27.97±2.92,无显著差异(t=1.9590,P=0.0540),而>6的时点数分别为25.66±4.98、20.32±3.72,差异显著(t=5.2828,P=0.0000)。两组发生上消化道出血分别为1例与11例(x~2=5.7220,P=0.0168),差异有统计学意义。结论SAP患者早期胃内pH值的高低与病情严重度及上消化道出血发生的危险性高度相关,静脉持续输注PPI能更迅速地提高胃内pH值,并能有效维持高pH值状态,减少上消化道出血的发生。     

Effect of a silver device in preventing catheter-related infections in peritoneal dialysis patients: silver ring prophylaxis at the catheter exit study

Catheter-related infections remain a significant cause of method failure in chronic peritoneal dialysis (PD) therapy. Given the increasing antibiotic resistance, such nonpharmacological strategies as local silver devices attract more interest. To establish whether a silver ring device (designed by Grosse-Siestrup in 1992) mounted onto the PD catheter and placed at the exit site at skin level is effective in preventing exit-site and other catheter-related infections, a prospective 12-month, multicenter, controlled study stratified by diabetes status was conducted. The study subjects were assessed by an extensive structured inventory, including a broad spectrum of control variables, such as age, body mass index (BMI), Staphylococcus aureus carrier status, catheter features, mode and quality of PD therapy, comorbidity, and psychosocial rehabilitation. Ten experienced German outpatient dialysis centers (seven adult, three pediatric) participated in the trial. All eligible patients (n=195) from the study area without catheter-related infections during the ascertainment period were included (incidental subjects undergoing PD therapy for at least 3 months). The main outcome measures were the occurrence of first exit-site infections (primary study end point), sinus tract/tunnel infection, and peritonitis. Ninety-seven patients were assigned to the silver ring and 98 patients to the control group. Baseline characteristics of age, sex, proportion of pediatric and incidental patients, S aureus carrier status, and other variables were similar in both groups. The incidence of infections in the silver ring group versus the control group was as follows: 23 of 97 versus 16 of 98 patients had exit-site infections, 12 of 97 versus 12 of 98 patients had sinus tract/tunnel infections, 16 of 97 versus 18 of 98 patients had peritonitis, respectively. Kaplan-Meier analysis for the probability of an infection-free interval showed no statistical difference (log-rank test) between the two groups. Displacement of the silver ring contributed to study termination in 6% of the study group patients, including two patients with catheter loss. Univariate analysis and multiple logistic regression identified younger age (<50 years), low serum albumin level (<35 g/L), number of previously placed PD catheters, short cuff-exit distance (<2 cm), and S aureus nasal carriage as risk factors for the development of exit-site infections. In conclusion, our study does not show any benefit of the silver ring in preventing catheter-related infections in PD patients. Thus, prevention of infection-related method failure in PD still has to rely on conventional antibiotic treatment strategies and less so on alternative methods.     

Acute spinal cord injury: MR imaging at 1.5 T

Thirty-seven magnetic resonance (MR) imaging studies were performed with a 1.5-T magnet and surface coils in 27 patients with suspected spinal cord injuries. Imaging was performed 1 day to 6 weeks after injury. Cord abnormalities were seen with MR in 19 patients, while skeletal and/or ligamentous injuries were seen in 21 (78%). Three types of MR signal patterns were seen in association with cord injuries. Acute intraspinal hemorrhage was seen in five patients with cord injuries and demonstrated decreased signal intensity on T2-weighted images obtained within 24 hours of injury. Cord edema and contusion had high signal intensity on T2-weighted images and were observed in 12 cases with cord injury. Neurologic recovery, determined in 16 patients, was insignificant in patients with intraspinal hemorrhage; however, patients with cord edema or contusion recovered significant neurologic function. MR at 1.5 T is extremely useful in the diagnosis of acute cord injury and also demonstrates potential in predicting neurologic recovery.     

Evidence for a cyclic GMP mechanism in the mediation of hippocampal post-tetanic potentiation

Correlative electrophysiological and biochemical techniques were used to study hippocampal post-tetanic potentiation in acutely prepared rabbits following stimulation of the medial septal region and contralateral hippocampal field CA3. The results indicate that calcium ions, guanosine-3':5'-monophosphate, and phosphodiesterase inhibitors selectively enhanced the duration of post-tetanic potentiation. Potassium ions selectively enhanced tetanic potentiation. Adenosine-3':5'-cyclic monophosphate suppressed both tetanic and post-tetanic potentiation. The electrophysiological findings were supported by biochemical observations that guanosine-3':5'-monophosphate levels show marked increases following tetanic stimulation of either the medial septal region or contralateral hippocampal field CA3 pathways. The data suggest that a calcium-dependent process in the presence of a guanosine-3':5'-monophosphate mechanism promotes periods of hippocampal pyramidal cell hyperexcitability. The mechanism by which the cyclic nucleotide alters potentiation does not appear to be coupled to a single receptor variety.     

Effects of certain indoleamines in the hippocampal-septal circuit

The effects of 5-HT and DMT upon the electrical activity in the lateral septal region, and region CA1 of the hippocampus, were studied in acutely prepared cats. Both 5-HT and DMT were found to have a facilitory effect on the firing of septal and hippocampal cells. Moreover, the facilitory effect of 5-HT in the lateral septal region appeared to be the result of a depolarizing action upon the cell membrane. Methiothepin was found to be an effective blocker of the DMT and 5-HTP induced effect, but not the 5-HT induced effect.     

Organization of projection neurons of the hippocampus

The origin of the fornix system was investigated by the horseradish peroxidase (HRP) technique. Small injections of HRP into the septal region resulted in labeling of neurons in both the pyramidal and nonpyramidal layers. Labeled neurons in the stratum pyramidale were seen in CA3 (bilaterally), CA2, CA1, and the adjacent subicular complex. Different patterns of uptake were observed in those hippocampal subfields. Numerous neurons in stratum oriens also displayed HRP positivity. These neurons were both polymorphic and spindle shape. The neurons were mainly restricted to the ventral portions of the hippocampus but labeled neurons were also seen in more dorsal levels. Furthermore, scattered neurons in stratum radiatum also displayed HRP positivity. These data demonstrate that some neurons generally considered to be interneurons are indeed projection neurons of the hippocampus.     

Electrophysiological studies of the septal nuclei: I. The lateral septal region

Electrophysiological studies of the lateral septal region were performed on acutely prepared cats. The data indicate that the lateral septal region consists of two functionally distinct zones: a dorsal zone (i.e., dorsal septal nucleus) and a ventral zone (i.e., lateral septal nucleus). The dorsal septal nucleus receives a heavy ipsilateral fimbria projection, but receives no projection via the ventral septal afferent system. There is no return projection through the fimbria. Test responses recorded from the dorsal septal nucleus show prolonged periods of suppression. The lateral septal nucleus receives a lesser share of the ipsilateral fimbria input, but does receive input via the ventral septal afferent system. Convergence upon single cells between ipsilateral fimbria and ventral septal afferent input was an outstanding feature of lateral septal nucleus organization. Cells in the lateral septal nucleus project out of the lateral septal region in both dorsal and ventral directions.