Changes in lipoprotein (a) [Lp(a)] level after an ischemic stroke

The aim of the work was to recognize whether often observed high levels of apolipoprotein (a) [Lp(a)] in patients shortly after an ischemic stroke are a result of the acute phase reaction. In 13 patients Lp(a) was determined within the first 24 hours after the stroke onset, after the next 7 days and after three months i.e. when it could be considered that Lp(a) level was the same as before onset of the disease. In 17 patients only two determinations were performed. Another acute phase indicator: C-reactive protein (CRP), as well as serum lipids were also determined. CRP level was increased in the first determination and increased further after 7 days. After three months it returned to low values. High density lipoprotein (HDL) cholesterol which demonstrates a negative acute phase response changed in the opposite way. No similar fluctuations of Lp(a) level were observed. It can be concluded that during the investigated period Lp(a) had no properties of the acute phase reactant.     

细胞外钙离子浓度对海马神经元兴奋性的影响(英文)

目的在不同的生理、病理情况下,中枢神经系统细胞外钙离子浓度([Ca2 ]o)下降,导致神经元兴奋性增高。本研究的主要目的是探讨低钙条件下神经元兴奋性增高的机制,从而为临床治疗神经元过度兴奋性疾病探索新的治疗途径。方法应用穿孔膜片钳及细胞培养技术,记录不同细胞外钙离子浓度对海马神经元兴奋性的影响。结果低钙环境使神经元兴奋性显著增高,阈电位水平显著降低,动作电位幅度显著增高。并且出乎意料的是,mAHP拮抗剂apamin及sAHP拮抗剂Iso对海马神经元兴奋性的影响没有统计学的意义。作为INaP拮抗剂,低浓度的河豚毒(TTX)虽然阻断了低钙环境中神经元兴奋性的增加,但同时也阻断了正常钙离子浓度下的动作电位的发放。结论低钙环境中海马神经元阈电位的显著下降可能是导致神经元兴奋性增高的主要原因。     

Autoradiographic localization of (125)I[Tyr(14)]orphanin FQ/nociceptin and (125)I[Tyr(10)]orphanin FQ/nociceptin(1-11) binding sites in rat brain

The endogenous ligand for the orphan opioid receptor, orphanin FQ/nociceptin (OFQ), has recently been characterized. The OFQ peptide sequence contains paired basic amino acids, suggesting the possibility of posttranslational processing to a peptide containing the first 11 amino acids of the OFQ peptide. This peptide has been reported in the brain and it has a unique pharmacology. In the present study, we compared the autoradiographic distribution of (125)I[Tyr(14)]OFQ and (125)I[Tyr(10)]OFQ(1-11) in coronal rat brain sections. Nonspecific binding was defined with unlabeled OFQ or OFQ(1-11), respectively. Both radioligands demonstrated high levels of specific binding (>95% of total binding), with no appreciable binding in white matter areas with either ligand. (125)I[Tyr(14)]OFQ binding was widely distributed throughout the rat brain. In contrast, (125)I[Tyr(10)]OFQ(1-11) binding was more restricted. The highest (125)I[Tyr(14)]OFQ binding levels measured in this study were found in the locus coeruleus, an area which contained very low (125)I[Tyr(10)]OFQ(1-11) binding. Both ligands labeled the cortex, hippocampus and amygdala. In the thalamus, (125)I[Tyr(14)]OFQ binding was prominent in most nuclei, whereas (125)I[Tyr(10)]OFQ(1-11) binding was restricted to the midline thalamus. (125)I[Tyr(14)]OFQ binding was heavy in the suprachiasmatic hypothalamus, and moderate in other hypothalamic nuclei. (125)I[Tyr(10)]OFQ(1-11) binding in the hypothalamus, however, was present mainly in the ventromedial hypothalamic nucleus. Lower binding levels of both ligands were found in the caudate putamen. The distinct autoradiographic patterns of these two ligands are consistent with different binding sites, which might help explain their different functional activities.     

The distribution of Histidyl-Proline Diketopiperazine [cyclo(His-Pro)] in discrete rat hypothalamic nuclei

The distribution of Histidyl-Proline Diketopiperazine [cyclo(His-Pro)], a metabolite of thyrotropin-releasing hormone (TRH), was determined by specific RIA in Palkovits micropunch pools derived from discrete hypothalamic nuclei. Highest concentrations of cyclo(His-Pro) were identified in the anterior nucleus (3.5 ng/mg protein) and the paraventricular nucleus (2.95 ng/mg protein), while lower concentrations of cyclo(His-Pro) were seen in the other 6 nuclei. In contrast, TRH concentrations were highest in the ventromedial nucleus pars medialis (3.2 ng/mg protein) and arcuate nucleus (2.7 ng/mg protein). This qualitatively different distribution of cyclo(His-Pro) from that of TRH suggests that not all of cyclo(His-Pro) is derived exclusively from TRH.     

川楝素对大鼠肾上腺嗜铬细胞胞内游离钙浓度的影响

在单个大鼠肾上腺嗜铬细胞上,采用Fura-2显微荧光测量技术,测定了川楝素对胞内游离钙浓度（[Ca^2 ]i)的影响,结果表明,川楝素作用于大鼠嗜铬细胞数十秒内邓可导致[Ca^2 ]i的作用。在胞外液中加入thapsigargin排空钙库后却不能止川楝素对[Ca^2 ]i的作用。提示,川楝素可以引起细胞外Ca^2 内流,而对钙库似无影响。     

化学致剂马桑内酯导致大鼠海马神经细胞内Ca~(2 )升高

于培养的新生大鼠海马神经细胞,应用ｆｕｒａ２ 荧光检测技术,观察了致疒间剂马桑内酯对单个海马神经细胞内钙离子浓度（［Ｃａ２＋ ］ｉ）的影响。培养液内马桑内酯浓度达１０－ ８ｍ ｏｌ／Ｌ时可引起［Ｃａ２＋ ］ｉ增加,［Ｃａ２＋ ］ｉ随给药浓度的提高而升高。马桑内酯浓度达５×１０－ ８ｍ ｏｌ／Ｌ时,［Ｃａ２＋ ］ｉ维持于稳定的高水平上。当胞外无Ｃａ２＋时,马桑内酯仍可引起［Ｃａ２＋ ］ｉ的升高;Ｌ型钙通道阻断剂ｖｅｒａｐａｍ ｉｌ不能阻断马桑内酯的上述作用。结果提示,海马神经细胞在致疒间剂作用下,发生Ｃａ２＋ 内流及胞内钙池释放现象。     

Characterization of [Phe(13), Tyr(19)]-MCH analog binding activity to the MCH receptor

Melanin concentrating hormone (MCH), a hypothalamic neuropeptide, is an important regulator of energy homeostasis in mammals. Characterization of an MCH specific receptor has been hampered by the lack of a suitable radioligand. The [Phe(13), Tyr(19)]-MCH analog has been shown by different investigators to bind specifically to cell lines of epithelial or pigment cell origin. Recently, using functional assays, the MCH receptor has been characterized as a seven transmembrane G-coupled protein initially identified as SLC-1. In the present study, we used tyrosine iodinated [Phe(13), Tyr(19)]-MCH analog, which stimulates food intake in a manner similar to that of MCH, as well as native MCH to conduct binding studies. Specific binding could not be demonstrated in intact cells of several cell lines, including A431 and B16. Specific binding associated with membranes localized to the microsomal, not the plasma membrane, fraction. Message for SLC-1 was absent in these cell lines, as assessed by Northern blot analysis. We conclude that cells previously reported to express the MCH receptor do not express SLC-1 and that both iodinated MCH and the [Phe(13), Tyr(19)]-MCH have a large component of non-specific binding. These ligands may be useful for binding studies in transfected cells with high levels of SLC-1 expression. However they do not appear to be suitable for screening for the MCH receptor as most cells demonstrate significant low affinity non-specific binding.     

Determination of lipoprotein (a) [Lp(a)] in patients with ischemic stroke. Preliminary communication

The aim of this work was the determination of apolipoprotein(a) [Lp(a)] in the patients three months after the onset of ischaemic stroke. A group of 56 patients was investigated. Stroke was diagnosed as caused by atherosclerotic changes in main cerebral arteries in 32 patients and in 11 by changes in cervical arteries. In 13 persons a lacunar stroke was recognised. The mean Lp(a) level and the median value were significantly higher in the group of patients after stroke as compared with 45 controls. A more frequent occurrence of Lp(a) level over 30 mg/dl considered as pathological was observed more often in the patients. No correlation was seen between Lp(a) and the resistance of LDL to oxidation nor between Lp(a) and the amount of products of LDL oxidation in vitro.     

Bis(7)-tacrine, a novel dimeric AChE inhibitor, is a potent GABA(A) receptor antagonist

Heptylene-linked bis-(9-amino-1,2,3,4-tetrahydroacridine) (bis(7)-tacrine) is a potential palliative therapeutic agent for Alzheimer's disease (AD), on the basis of its superior acetylcholinesterase (AChE) inhibition and memory-enhancing potency relative to tacrine. In this study we report that bis(7)-tacrine exhibits a potentially complementary central nervous system action, antagonism of GABA(A) receptor function. Bis(7)-tacrine displaced [3H]muscimol from rat brain membranes with an apparent Ki of 6.0 microM; tacrine and physostigmine were shown to be 18 and 170 times less potent, respectively. In whole-cell patch-clamp recordings, bis(7)-tacrine inhibited GABA-induced inward current with an IC50 of 5.6 microM, and shifted the GABA concentration-response curve to the right in a parallel manner. These results suggest that bis(7)-tacrine is a competitive antagonist of the GABA(A) receptor.     

Gene therapy for cerebral infarction (cerebral ischemia)]

The treatment strategies of cerebral infarction have been studied in order to prevent neuronal cell death. Gene therapy is one of the most promising therapy and has several advantage over classical drug therapies. There has been a problem that drug proteins are unable or difficult to pass through blood brain barrier. In gene therapy, however, drug proteins are expressed in the brain with transgene transfer technique. Ischemic neural death proceeds with a complex series of pathophysiological events in the neurons. But molecular mechanism of ischemic neuronal cell death gradually understood. It has been known that a number of genes can be potent candidates for treatment factors of cerebral infarction. Actually, many investigators have been studied treatment strategies of cerebral infarction using a variety of neurotrophic factors such as bcl-2, heat shock protein 72, glial cell line-derived neurotrophic factor (GDNF), and hepatocyte growth factor (HGF). Moreover, the development of new vectors and gene delivery systems have been studied. Gene therapy would be a strong strategy for treatment of cerebral infarction in the future.     

钙离子在颞叶癫大鼠海马神经元内的动态变化

目的探讨海马神经元内钙离子浓度的动态变化在颞叶癫中的可能作用。方法应用新一代钙荧光指示剂Fluo3/AM,采用激光共聚焦扫描显微镜技术对颞叶癫大鼠海马神经元内的钙离子浓度变化进行动态观察。结果各时间点癫组大鼠海马神经细胞的平均荧光像素数(3h:634942±27735;12h:697066±14863;7d:732844±23107;60d:800030±16450)均明显高于对照组(3h:396499±31951;12h:389498±33257;7d:389809±29486;60d:392758±35197),差异有统计学意义(P<0.01);癫大鼠海马神经细胞内钙离子浓度的变化可分3个阶段:急性期细胞内的钙离子浓度先急剧升高,然后缓慢升高;静止期开始时钙离子浓度较急性期后期先稍有下降,然后再次缓慢上升;到慢性复发期,钙离子浓度达到最高峰,并维持在高水平。结论在颞叶癫的发生发展过程中海马细胞内存在钙稳态失调,该变化导致了神经元内游离钙离子浓度的急性和持久性升高,后者可能诱发了颞叶癫的自发性复发性发作。     

Peripheral neuropathy in mutant diabetic mouse [C57BL/Ks (db/db)]

Summary A new animal model for the study of diabetic neuropathy is presented. The homozygote (db/db) of the mouse strain C57BL/Ks shows severe diabetes with longstanding hyperglycemia. Electrophysiological studies showed severely decreased motor nerve conduction velocity. Morphometric examination of sensory and motor nerves at different levels revealed absence of large myelinated fibers, with morphological features indicative of axonal atrophy.Supported by Grant No. MA-5857 from the Medical Research Council of Canada     

Transplacental transfer of the opioid growth factor, [Met(5)]-enkephalin, in rats

Placental transfer of the pentapeptide [Met5]-enkephalin, known to function as a growth regulating factor and neuromodulatory agent, was studied in pregnant Sprague-Dawley rats. Using separation by reversed phase high-performance liquid chromatography, and analysis by derivative spectroscopy, [Met5]-enkephalin was detected in 20-day-old fetal tissue including brain, heart, lung, and kidney. Fetal tissues from pregnant rats given an injection of 40 mg/kg [Met5]-enkephalin on gestation day 20 had markedly elevated levels of peptide within 1 h, indicating the transplacental transfer of this opioid. [Met5]-enkephalin levels were increased from control samples at 1, 2, 4, and 14 h post-injection of peptide, but not at 24 h. Evaluation of breakdown products of [Met5]-enkephalin, along with the related peptide [Leu5]-enkephalin, revealed that elution times differed substantially from [Met5]-enkephalin. These data indicate that [Met5]-enkephalin is present in fetal organs, crosses the placenta, does not appear to be restrictive in organ specificity, and is sustained in fetal tissues at detectable levels for at least 14 h. Given that [Met5]-enkephalin tonically inhibits DNA synthesis in the fetus, these results raise the question of whether an elevated level of this peptide (either maternally or from the fetus) may be detrimental to cellular ontogeny in the fetus, and perhaps have long-term implications for postnatal development.     

脑缺血再灌流［~3H］—三磷酸肌醇放射活性及突触体游离Ca~（2＋）的变化

本文研究了大鼠脑缺血再灌流时［３Ｈ］—三磷酸肌醇（［３Ｈ］－ＩＰ３）放射活性及突触体游离Ｃａ２＋（［Ｃａ２＋］ｉ）的变化，并用苯甲基磺酰氟化物（ＰＭＳＦ）治疗，观察其对［３Ｈ］－ＩＰ３放射活性及突触体［Ｃａ２＋］ｉ的影响。结果：脑缺血１ｍｉｎ［３Ｈ］－ＩＰ３放射活性非常显著地增高。缺血２０ｍｉｎ、缺血２０ｍｉｎ再灌流１ｈ、６ｈ、２ｄ［３Ｈ］－ＩＰ３放射活性非常显著地降低。缺血２０ｍｉｎ突触体［Ｃａ２＋］ｉ非常显著地增高，至再灌流６ｈ达到最高水平。应用ＰＭＳＦ治疗能显著地抑制突触体［Ｃａ２＋］ｉ的升高。     

Distribution of histidyl-proline diketopiperazine [cyclo (His-Pro)] and thyrotropin-releasing hormone (TRH) in the primate central nervous system

The concentrations of cyclo (His-Pro) and its precursor, thyrotropin-releasing hormone (TRH) were measured in 47 different loci of monkey brain using specific radioimmunoassays. Cyclo (His-Pro) concentrations were higher than those of TRH in all loci excepting the hypothalamus, where TRH concentration was found to be the highest of all the loci and twice those of cyclo (His-Pro). The high levels of cyclo (His-Pro) were seen within the cerebellar system (inferior olivary nucleus>nucleus interpositus>fastigial nucleus>posterior vermis). The great variations in TRH-cyclo (His-Pro) ratios among different loci suggest that other factors in addition to TRH concentration must play roles in determining the unique distribution pattern of cyclo (His-Pro) in the primate brain.     

Corticotrophin-Releasing Factor Antagonist [alpha helical CRF(9–41)] Blocks Central Noradrenaline-lnduced ACTH Secretion

Plasma ACTH increased after an intra-third ventricular administration of noradrenaline (NA). An iv corticotrophin-releasing factor (CRF) antagonist [alpha-helical CRF(9–41)] injection did not affect ACTH secretion by itself, whereas it significantly reduced NA-induced ACTH secretion. These results suggest that NA centrally stimulated ACTH secretion and that endogenous CRF is involved in this ACTH secretion.