大鼠脊髓压迫损伤减压后钙离子和兴奋性氨基酸的变化

目的 :SS研究大鼠脊髓压迫损伤减压后钙离子和兴奋性氨基酸变化及其与神经功能恢复的关系 .方法 :将动物随机分为 :慢性渐进性脊髓损伤组 ,慢性渐进性脊髓损伤减压 1,7,14 ,2 8d组 .取伤段脊髓 ,用高效液相色谱法检测谷氨酸和天门冬氨酸的含量的变化 ,用原子吸收光谱法测定其离子改变及水含量 .结果 :慢性渐进性脊髓损伤减压后钙离子和兴奋性氨基酸有明显的降低 ,减压后 1,7,14 ,2 8dGlu(μmol·g-1)分别为 :6 .16± 0 .16 ,5 .4 3± 0 .2 2 ,5 .4 3± 0 .17,5 .33± 0 .2 0 ;Asp(μmol·g-1)分别为 :3.39± 0 .12 ,2 .96±0 .11,2 .92± 0 .16 ,2 .89± 0 .15 ;Ca2 + 离子 (μmol·kg-1)分别为 :5 .84± 0 .11,5 .33± 0 .10 ,5 .2 8± 0 .17,5 .2 4± 0 .0 2 .它们均较减压前 (Glu为 6 .32± 0 .10 μmol·g-1,Asp为 3.5 6±0 .13μmol·g-1,Ca2 + 为 6 .5 3± 0 .6 4 μmol·kg-1)有显著降低 (P <0 0 5 ) ,其中前 7d降低较快 ,以后有降低不明显 .减压后 1,7,,14 ,2 8d改良的Tralov评分分别为 3.5 3± 0 .11,3.74± 0 .12 ,3.86± 0 .12 ,3.88± 0 .10 ;斜板试验分别为 4 3.3± 2 .3,4 6 .2± 1.1,4 8.8± 2 .8,4 9.7± 2 .6 ,均较减压前Tralov评分 (3.4 0± 0 .13)斜板试验 (40 .9± 1.8)有显著升高     

Transmitter Release Associated with Long-term Synaptic Depression in Rat Corticostriatal Slices

Using a corticostriatal slice preparation, we have recently shown that tetanic stimulation of the corticostriatal pathway produces long-term depression (LTD) of striatal excitatory synaptic transmission. In the present study we have analysed the relationship between LTD and the striatal release of different endogenous transmitters. Samples of perfusate were collected via a small cannula placed just above the surface of the striatal slice close to the recording electrode, and were analysed by HPLC. The high-frequency stimulation (100 Hz, three trains, 3 s duration, 20 s intervals) used to induce LTD caused a significant but transient increase in the release of both excitatory (aspartate and glutamate) and inhibitory (glycine and GABA) amino acid transmitters. Tetanic stimulation also produced a significant, but transient increase in the release of endogenous dopamine. We conclude that the tetanic stimulation of the corticostriatal pathway is able to induce a large but transient release of excitatory amino acids and of dopamine, whose participation in the induction of striatal LTD has been demonstrated previously. Moreover, the maintenance of this form of synaptic plasticity does not seem to require a sustained change in transmitter release.     

N-3 fatty acids only delay early relapse of ulcerative colitis in remission

Relapse prevention by dietary n-3 fatty acids (5.1 g/day) was studied in a double-blind, placebo-controlled trial of 64 patients with ulcerative colitis in remission and off steroids. 5-ASA compounds were stopped three months after randomization and clinical disease activity monitored for two years. Macroscopic and histologic activity and extension was assessed by colonoscopy at entry and at exit. Both treatment groups were well matched at start. Nine patients on placebo and eight on n-3 fatty acids stopped taking their medication prematurely. Actuarial relapse-free survival was improved by n-3 fatty acids only during months 2 and 3 (2P<0.05–0.01), but cumulative relapse rate at two years was similar for those taking placebo (18/33=55%) and n-3 fatty acids (18/31=58%). There was also no consistent difference in clinical, macroscopic, and histologic disease activity between treatment groups. The n-3 fatty acids temporarily retard, but do not prevent, relapse of ulcerative colitis.     

Interactions between epidermal growth factor-mediated autocrine regulation and linoleic acid-stimulated growth of a human prostate cancer cell line.

Human prostate cancer (PC) cell lines possess epidermal growth factor (EGF) receptors and secrete EGF-related polypeptides. We used an EGF receptor-blocking antibody (anti-EGF.R) to demonstrate a functional autocrine loop, as well as the interaction between this and the effects of linoleic acid (LA), an omega-6 fatty acid, on PC cell growth. The anti-EGF.R competed effectively with [125I]EGF for receptors on DU145 PC cells, and on a high-passage DU145 variant (DU145M); when added to the culture medium, it suppressed both DU145 and DU145M cell growth in a dose-dependent manner. LA, a precursor for eicosanoid synthesis, had little effect on DU145 cell growth rate but stimulated DU145M growth in a concentration-related manner over a range of 0.25-2.0 micrograms/ml. anti-EGF.R (10(-9) M) caused suppression of LA-stimulated growth of DU145M cells in serum-free medium, which was prevented by the addition of 2 nM EGF. We conclude that an EGF.R-mediated autocrine loop is involved in PC cell growth regulation and that at least one site of action may be the synthesis of eicosanoids from their LA precursor.     

急性颅脑损伤患者脑脊液中兴奋性和抑制性氨基酸含量改变及其临床意义

采用氨基酸自动分析仪检测了１８例急性颅脑损伤患者脑脊液中谷氨酸、天门冬氨酸、牛磺酸、甘氨酸、丙氨酸、γ－氨基丁酸、脯氨酸含量的动态变化。结果发现，伤情越重、预后越差的患者，脑脊液中牛磺酸、γ－氨基丁酸、丙氨酸含量伤后早期升高越明显，恢复至正常的时间也越长；其中２例早期死于急性弥漫性脑肿胀、脑水肿的患者，伤后当天脑脊液中牛磺酸含量分别为９２．６和５１．５μｍｏｌ／Ｌ，是对照值的９．６倍和５．４倍，γ－氨基丁酸含量分别为１１９．８和２４６．２μｍｏｌ／Ｌ，是对照值的２．７倍和５．５倍。表明伤后脑脊液中牛磺酸、γ－氨基丁酸和丙氨酸含量的动态变化可初步反映颅脑损伤的严重程度及颅脑损伤患者的脑功能恢复状况，并可能与急性脑水肿、脑肿胀的病理生理过程有关。     

Suppression of the nocturnal free fatty acid levels by bedtime cornstarch in NIDDM subjects

The aim of the present study was to examine the effects of a large dose of slow-release carbohydrates (CHOs) at bedtime on the nocturnal glucose, insulin and free fatty acid (FFA) levels, and to assess the putative effects on morning fasting and post-prandial glucose levels in patients with moderately controlled non-insulin-dependent diabetes mellitus (NIDDM). Unheated cornstarch (106 g of CHO) or a mixed equicaloric meal (58 g of CHO) was given at 22.00 hours to 10 NIDDM patients. For comparison, the patients were also given a smaller mixed meal at 22.00 hours on a third occasion (17 g of CHO). Compared with the mixed meals, cornstarch led to a slightly elevated early-morning plasma insulin level and a suppression of the nocturnal FFA level ( P  < 0.05), as well as to a reduced incremental glucose level (IAUC) after breakfast the next morning by approximately 30% ( P  < 0.05). There was a significant and linear relationship between the nocturnal FFA level and the glucose IAUC after breakfast ( r  = 0.44, P  < 0.02), indicating that the effect may have been mediated by the suppressive effect of cornstarch on nocturnal lipolysis. In summary, bedtime intake of unheated cornstarch in NIDDM subjects is associated with a suppression of the nocturnal FFA levels and a reduced glucose IAUC after breakfast. As the treatment did not improve overall glucose control, studies of the effects of an individually titrated amount of cornstarch are proposed to further explore the putative favourable effects of bedtime cornstarch in the treatment of NIDDM.     

Protective Effect of Tetrandrine against Excitatory Amino Acids induced Neuronal Injury in Cortical Culture

兴奋性氨基酸类神经毒剂与粉防己碱（ｔｅｔｒａｎｄｒｉｎｅ，Ｔｅｔ）共同作用于原代培养胎鼠大脑皮层神经元２４小时，发现１０７，１０６ｍｏｌ·Ｌ１Ｔｅｔ明显降低５０μｍｏｌ·Ｌ１谷氨酸（ｇｌｕｔａｍａｔｅ，Ｇｌｕ），３００μｍｏｌ·Ｌ１βＮｍｅｔｈｙｌａｍｉｎｏＬａｌａｎｉｎｅ（ＢＭＡＡ，ＮＭＤＡ受体激动剂）和２０μｍｏｌ·Ｌ１βＮｏｘａｌｙｌａｍｉｎｏＬａｌａｎｉｎｅ（ＢＯＡＡ，ｎｏｎＮＭＤＡ受体激动剂）导致的培养液乳酸脱氢酶（ｌａｃｔａｔｅｄｅｈｙｄｒｏｇｅｎａｓｅ，ＬＤＨ）活性的增高；细胞形态损害减轻，细胞数量增加。对２０μｍｏｌ·Ｌ１ＮＭＤＡ介导的神经元损伤改变无影响。提示Ｔｅｔ对某些Ｇｌｕ类神经毒剂引起的胎鼠大脑皮层神经元损伤有一定保护作用，其机制可能是抑制细胞膜上的Ｎａ＋通道开放，阻止膜去极化而影响电压依赖性Ｃａ２＋通道启动。对ＮＭＤＡ受体可能亦有一定作用。     

Thoracic epidural analgesia in aortocoronary bypass surgery II: effects on the endocrine metabolic response

Thoracic epidural analgesia (TEA) may offer haemodynamic benefits for patients with coronary heart disease going through major surgery. This may – in part – be secondary to an effect on the endocrine and metabolic response to surgery. We therefore investigated the effect of TEA on the endocrine metabolic response to aortocoronary bypass surgery (ACBS).
Thirty male patients (age < 65 years, ejection fraction > 0.5) were randomized into 3 groups; the HF group receiving a high dose fentanyl (55 μg–kg^-1) anaesthesia, the HF + TEA group with the same fentanyl dose + TEA with 10 ml bupivacain 5 mg ml^-1, followed by 4 ml every hour, and the LF + TEA group receiving fentanyl 15 μg kg^-1 + TEA. Adrenalin, noradrenalin, systemic vascular resistance (SVR), glucose, Cortisol, lactate and free fatty acids were followed during the operation and for 20 h postoperatively.
A significant increase in adrenalin, noradrenalin and SVR was found in the HF group whereas this increase was blocked in both epidural groups. An increase in glucose and Cortisol was noticed in all groups, but the increase was delayed in the epidural groups.
Our results suggest that a more effective blockade of the stress response during ACBS is obtained when TEA is added to general anaesthesia than with high dose fentanyl anaesthesia alone.     

Extracellular adenosine,formed during low level NMDA receptor activation,provides an inhibitory threshold against further NMDA receptor-midiated neurotransmission in the cortex

In the cortex only a few of the available NMDA receptors must be activated to evoke maximal release of adenosine. In fact, maximal adenosine release occurs at 30 μM NMDA, a concentration at which noradrenaline release is only 20% maximal. NMDA-evoked noradrenaline release appears to require the generation of propagated action potentials, while adenosine release does not. Noncompetitive block of NMDA-evoked release of adenosine, but not noradrenaline, can be overcome by increasing NMDA concentrations. The above findings are consistent with the possibility that there are spare receptors for NMDA-evoked adenosine release, but not for nor-adrenaline release. These spare receptors are not due to elevated levels of glycine in the vicinity of those NMDA receptors mediating adenosine release. Functionally, it appears that low level NMDA receptor activation provides a purinergic inhibitory threshold against higher level NMDA receptor mediated processes. This could provide inhibitory tone and selectivity for critical functions, such as learning, memory, and synaptic plasticity in the cortex. © 1993 Wiley-Liss, Inc.     

反相高压液相色谱法测定血清中部分氨基酸

目的：建立测定血清中精氨酸含量的方法。方法：反相高压液相色谱法。ＨｙｐｅｒｓｉｌＢＤＳ柱，邻苯二甲醛柱前衍生化、萤光检测法检测。结果：精氨酸线性范围为３８３μｍｏｌ／Ｌ～４７８９μｍｏｌ／Ｌ，８种氨基酸的最低检测限为２μｍｏｌ／Ｌ，日内变异系数为２７５％～１１９３％，日间变异系数为７０５％～１２３９％，５种氨基酸的回收率为９６３３％～１００７８％。正常人血清精氨酸水平为９２７７±１７９０μｍｏｌ／Ｌ，糖尿病患者血清精氨酸水平则为７８６１±３３０３μｍｏｌ／Ｌ（Ｐ＞００５）。结论：本方法简单易行，方法学实验结果满意，适用于临床测定相关氨基酸的需要