Cerebral vasoconstriction in comatose patients resuscitated from a cardiac arrest?

Objective To determine the role of cerebral vasoconstriction in the delayed hypoperfusion phase in comatose patients after cardiac arrest.Design Prospective study.Setting Medical intensive care unit in a university hospital.Patients 10 comatose patients (Glasgow Coma Score 6) successfully resuscitated from a cardiac arrest occurring outside the hospital.Measurements We measured the pulsatility index (PI) and mean blood flow velocity (MFV) of the middle cerebral artery, the cerebral oxygen extraction ratio and jugular bulb levels of endothelin, nitrate, and cGMP during the first 24 h after cardiac arrest.Results The PI decreased significantly from 1.86±1.02 to 1.05±0.22 (p=0.03). The MFV increased significantly from 29±10 to 62±25 cm/s (p=0.003). Cerebral oxygen extraction ratio decreased also from 0.39±0.13 to 0.24±0.11 (p=0.015). Endothelin levels were high but did not change during the study period. Nitrate levels varied widely and showed a slight but significant decrease from 37.1 mol/l (median; 25th–75th percentiles: 26.8–61.6) to 31.3 mol/l (22.1–39.6) (p=0.04). Cyclic guanosine monophosphate levels increased significantly from 2.95 nmol/l (median; 25th–75th percentiles: 2.48–5.43) to 7.5 nmol/l (6.2–14.0) (p=0.02).Conclusions We found evidence of increased cerebrovascular resistance during the first 24 h after cardiac arrest with persistent high endothelin levels, gradually decreasing nitrate levels, and gradually increasing cGMP levels. This suggests that active cerebral vasoconstriction due to an imbalance between local vasodilators and vasoconstrictors plays a role in the delayed hypoperfusion phase.     

Delayed image of iodine-123 iomazenil as a relative map of benzodiazepine receptor binding: The optimal scan time

Delayed single-photon emission tomograpic (SPET) images after an intravenous bolus injection of iodine-123 iomazenil have been used as a relative map of benzodiazepine receptor binding. We determined the optimal scan time for obtaining such a map and assessed the errors of the map. SPET and blood data from six healthy volunteers and five patients were used. A three-compartment kinetic model was employed in simulation studies and analyses of actual data. The simulation studies suggested that, in the normal brain, the scan time at which a single SPET image best represented the relative receptor binding was 3.0–3.5 h post-injection. This finding was supported by actual data from the volunteers. The simulation studies also suggested that the optimal scan time was not greatly changed by the variability of the input functions, and that the error in the SPET image contrast in the vicinity of the optimal scan time was not increased by changes in the tracer kinetics in the entire brain. The SPET image contrast in the patients at 3.0 h post-injection agreed well with the reference receptor binding estimated by kinetic analysis, with a mean error of 3.6%. These findings support the use of a single SPET image after bolus injection of [¹²³I]iomazenil as a relative map of benzodiazepine receptor binding. For this purpose, a SPET scan time of 3.0-3.5 h post-injection is recommended.     

Unitary delayed rectifier channels of rat hippocampal neurons: properties of block by external tetraethylammonium ions

Patch-clamp recording was used to characterise a delayed rectifier potassium channel and the effects of external tetraethylammonium (TEA) in neurons isolated from the CA1 region of cultured neonatal rat hippocampus. A preliminary kinetic analysis is presented. Very low concentrations of TEA included in the patch pipette solution had two effects on unitary currents: first unitary currents were reduced in amplitude, with an associated increase in open channel noise, and second channel mean open time was reduced. The reduction in unitary amplitude was consistent with a single TEA molecule blocking the channel with a voltage-independent K _d of 53.4 M. The blocking and unblocking rate constants, estimated using two independent methods, were approximately 350 mM^–1 ms^–1 and 20 ms^–1, both rate constants being independent of voltage. Channels blocked in this way appeared able to close normally without first having to become unblocked. The reduction in mean channel open time was probably due to a second, kinetically slower blocking reaction with a much lower K _d, probably between 300 and 800 M. The voltage-independent blocking rate constant of the slower block was at least 25 times slower than that of the faster block.     

Memory and the septo-hippocampal cholinergic system in the rat

This study examined the effects of intrahippocampal injections of scopolamine (a muscarinic antagonist drug) on performance of a working-memory task (contingently) reinforced T-maze alternation) and a reference-memory task (visual discrimination) by the same rats in the same maze. Rats in the first shipment were trained in delayed alternation, received bilateral implantation of cannulae aimed at the CA3 field of the dorsal hippocampus, and were tested for retention with 1 l microinjections of scopolamine (35 g) and saline on alternate days. These rats were then trained on visual discrimination and tested alternately under scopolamine or saline as described above. It was found that scopolamine impaired performance of delayed alternation to a greater extent than performance of visual discrimination. Data from rats in the second shipment replicated this finding, with the order of the tasks reversed, and, additionally, showed that delayed alternation, but not visual discrimination, was impaired at a dose of 12 g/l. A dose of 4 g/l had no effect on either task. It is concluded that performance of a workingmemory task is significantly more sensitive to disruption of cholinergic mechanisms in the hippocampus than performance of a reference-memory task.Supported by PHS Training Grant MH-14577. Now at the Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA 94305, USA     

Web creep: the role of infection and delayed healing

Summary Twenty-five digital webs from 21 patients, where web creep was noted after division of simple syndactyly were reviewed. In all cases web creep was related to delayed healing and the average time to its appearance was 8 months.     

银杏苦内酯A对心室肌细胞延迟整流钾电流的影响

目的:研究银杏苦内酯A对豚鼠心室肌细胞延迟整流钾电流的影响.方法:全细胞膜片钳记录心室肌细胞延迟整流钾电流.结果:银杏苦内酯A 0.1,1.0,10.0 μmol•L 1分别使延迟整流钾电流减小5.34%(n＝7,P＞0.05),9.92%(n＝6,P＜0.05)和27.64%(n＝7,P＜0.05),并且具有浓度依赖性.结论:银杏苦内酯A能减少延迟整流钾电流且具有浓度依赖性.     

外伤性颌骨骨折的临床诊治分析

目的：探讨骨折愈合影响因素。方法：对358例颌骨骨折病例，根据致伤原因、骨折部位及类型，治疗效果及随访结果进行总结。结果：治疗有效率95．87％。手术切开复位骨间固定265例，手法或牵引复位外固定93例；术后感染骨延迟愈合8例；合并口腔颌面部软组织损伤210例。结论：准确诊断，及时复位、固定，选择正确固定方式，防止感染，待别是应用坚固内固定技术能有效提高颌骨骨折治愈率。     

免疫抑制活性物质335A对小鼠免疫功能的影响

对链霉菌 335产生的代谢产物 335 A的体外、体内免疫反应的作用进行了研究。结果表明 ,335 A体外对小鼠脾细胞的增殖反应及混合淋巴细胞反应均呈强烈的抑制作用 ,半数抑制浓度 (IC50 )分别为 2 .2和10 ng/ ml,且是一种特异的 T细胞抑制剂。以上作用并不是非特异性细胞毒作用所致。通过不同时间加入335 A,显示其作用在 T淋巴细胞活化的早期。 335 A对三种实验动物模型的免疫抑制作用的研究表明 ,4 mg/ kg的 335 A对小鼠抗绵羊红细胞抗体产生的抑制率为 98.7% ,并对绵羊红细胞诱导的 DTH反应有明显的抑制作用 ;8mg/ kg的 335 A使小鼠移植心肌的存活时间由 (8.71± 0 .4 8) d延长至 (13.0± 0 .1) d。初步的作用机制研究表明它主要抑制 Th细胞分泌淋巴因子及其受体表达。     

Ostreopsis sp., a possible origin of palytoxin (PTX) in parrotfish Scarus ovifrons.

A clone of toxic dinoflagellate Ostreopsis sp. and six specimens of a parrotfish Scarus ovifrons were collected in October 1997 at Tokushima Prefecture, Japan. Ostreopsis sp. was cultured in ESM medium for 16 days, and after rearing the cell pellet (about 4.0x10(5) cells) was extracted with 50% methanol, partitioned between an aqueous layer and 1-butanol layer, and biochemically tested. Similarly, the crude toxin from S. ovifrons was extracted, and tested. The mice injected with each 1-butanol layer from Ostreopsis sp. and S. ovifrons showed the common symptoms of convulsion, drowsiness and collapse, and died within 48 h. The lethal potency of Ostreopsis sp. was calculated to be 1.0x10(-4) MU/cell. All specimens of S. ovifrons were found to be toxic, where the highest potency was determined as 2 MU/g in muscle of one specimen. After being injected with toxins, the serum creatine phosphokinase levels of mice were found to be elevated. Toxins from Ostreopsis sp. and S. ovifrons showed delayed haemolytic activity with mouse and human erythrocytes, which was inhibited by an anti-palytoxin (PTX) antibody antibody and ouabain. Toxins from Ostreopsis sp. and S. ovifrons thus resembled each other, and strongly suggested to be PTX or its akin substance. Additionally, a considerable number of adherent Ostreopsis sp. was found in the gut contents of S. ovifrons during the heavy occurrence of Ostreopsis sp. in October 1997 at Tokushima Prefecture. From the above results, it can be strongly postulated that the dinoflagellate Ostreopsis sp. is the origin of PTX which is sequestered by the parrotfish S. ovifrons through food chain.     

外伤后迟发性颅内血肿临床分析

目的　探讨外伤后迟发性颅内血肿的发病原因、诊断、治疗和预防措施。方法　回顾分析 2 4例外伤后迟发性颅内血肿的临床资料。结果　 2 1例治愈 ,其中 15例完全康复 ,6例有不同程度的神经功能障碍 ,死亡 3例。结论　年龄因素、受伤部位、凝血功能异常、过量脱水和减压是出现外伤后迟发性颅内血肿的诱发因素 ;伤后 72h内为发病高峰 ,绝大多数发生于伤后 36h内 ;伤后早期严密观察病情变化、动态复查头颅CT是确诊关键