GABA inhibition of immortalized gonadotropin-releasing hormone neuronal excitability involves GABA(A) receptors negatively coupled to cyclic adenosine monophosphate formation

γ-Aminobutyric acid (GABA) has been implicated in the regulation of reproduction, particularly in the developmental modulation of gonadotropin-releasing hormone (GnRH) secretion. GnRH neurons are innervated by GABA-containing processes, and the administration of GABA stimulates and inhibits GnRH secretion in vivo and in vitro. We have previously shown that GABA can exert both of these actions in sequence, by acting directly on immortalized GnRH neurons. While the stimulation is the result of a GABA_A receptor-mediated depolarization of the plasma membrane, the mechanism involved in the delayed inhibition is the subject of the present investigation. GABA (1 nM-10 μM) decreased the intracellular concentration of cyclic adenosine monophosphate (cAMP) in a dose- and time-dependent fashion. This effect was blocked by bicuculline and mimicked by muscimol but not by baclofen. To analyze the effect of GABA on cellular excitability, we used fura-2 loaded GT1-7 cells. Activation of voltage-sensitive calcium channels by high K⁺-induced depolarization (35 mM) increased [Ca²⁺]_i. GABA (10μM) and muscimol (10 μM) reduced the amplitude of K⁺-induced [Ca²⁺]_i transients. This inhibition was blocked by forskolin (20μM) or 8-Br-cAMP (1 mM). Altogether, these results show that GABA_A receptors mediate a sustained inhibitory effect of GABA on GnRH neurons, and suggest the involvement of the cAMP pathway decreasing cellular excitability.     

Predictive value of pulmonary function testing during pulmonary exacerbations in cystic fibrosis

The optimal duration of therapy for acute exacerbations of cystic fibrosis (CF) has not been defined, and the utility of serial pulmonary function testing in predicting the duration of therapy has yet to be established. In a review of 90 pulmonary exacerbations of 39 patients with CF requiring hospitalization, we found that 72% of the patients recovered following 2 weeks of intravenous antibiotics and aggressive chest physiotherapy, and that 28% required an extended third week of therapy. Recovery was delayed in patients with more severe chronic pulmonary disease, but the rate of improvement was independent of the degree of pulmonary deterioration with the acute exacerbation. A 40% recovery of FEV, at 1 week was found to correlate significantly with the duration of hospitalization in the 90 patients. When prospectively applied to a second series of consecutively hospitalized patients with CF, 25/28 patients admitted for 2 weeks demonstrated > 40% improvement in FEV, at 1 week, as compared to 5/10 patients subsequently treated for ≤3 weeks (P = 0.030). The predictive values for 2- or 3-week hospitalizations with 1-week interval recovery of > 40% or > 40% in FEV, were 79% and 62%, respectively. These findings suggest that the response to intensive therapy in CF exacerbations is variable and that improvements in pulmonary function after 1 week of therapy may be used to predict the subsequent duration of therapy in the majority of CF patients with pulmonary exacerbations. Pediatr Pulmonol. 1993; 16:227–235. © 1993 Wiley-Liss, Inc.     

赤峰市黄鼠鼠疫血清流行病学研究

目的了解黄鼠鼠疫现状，分析疫情动态，为防治鼠疫工作提供科学依据。方法选用鼠疫间接血凝试验（IHA）方法，对采集的黄鼠血清进行检测，依据GB16883—1997鼠疫自然疫源地及动物鼠疫现疫流行区判定标准判定疫区，对疫情进行流行病学分析。结果1995～2005年共设调查点99个，检验黄鼠血清21028份，阳性29份，FI抗体滴度在1：40～1：2560之间，阳性血清分布在6个年度8个地区，皆被判定为鼠疫现疫流行区。结论赤峰市黄鼠鼠疫已进入活跃期，建议各地积极采取综合性防治措施。血清流行病学方法调查鼠疫疫情，可缩短有限鼠疫疫源面积的监测周期。     

Comparison of the release of microRNAs and extracellular vesicles from platelets in response to different agonists

On activation platelets release microRNAs and extracellular vesicles (EV) into circulation. The release of EV from platelets has been shown to be dependent on the agonist; in this study, we investigated whether the microRNA profile or EV released from platelets was also agonist specific.

Washed platelets from healthy subjects were maximally stimulated with agonists specific for the receptors for collagen (Glycoprotein VI (GPVI)), thrombin (PAR1/PAR4), or ADP (P2Y1/P2Y12) with/without inhibiting secondary mediators, using aspirin to block cyclooxygenase-1 and apyrase to remove ADP. The released microRNAs were profiled using TaqMan microRNA microarray cards. Platelet-derived EV (pdEV) were characterized by size (Nanoparticle Tracking Analysis, NTA), for procoagulant activity (Annexin-V binding and support of thrombin generation), and for the EV markers CD63 and HSP70.

Platelet activation triggered the release of 57–79 different microRNAs, dependent upon agonist, with a core of 46 microRNAs observed with all agonists. There was a high level of correlation between agonists (r² > 0.98; p < 0.0001 for all), and with the microRNA content of the parent platelets (r² > 0.98; p < 0.0001). The 46 microRNAs seen in all samples are predicted to have significant effects on the translation of proteins involved in endocytosis, cell cycle control, and differentiation. MiR-223-3p was the most abundant in all samples and has previously been implicated in myeloid lineage development and demonstrated to have anti-inflammatory effects. Stimulation through GPVI produced a pdEV population with significantly more procoagulant activity than the other agonists. Apyrase significantly reduced microRNA and pdEV release, while aspirin had little effect.

These data suggest that all tested agonists trigger the release of a similar microRNA profile while the procoagulant activity of the pdEV was agonist dependent. ADP was shown to play an important role in the release of both microRNAs and pdEV.     

Is it necessary to adjust the replacement dose of thyroid hormone to the season in patients with hypothyroidism?

Hypothalamo-pituitary-thyroid activity varies with the temperature of the environment; we therefore measured variables involved with thyroid function in summer and winter in normal controls and in patients with primary hypothyroidism. All seven patients had impalpable thyroid glands and had received a set replacement dose of thyroxine for over a year. In the patients, serum T3 and FT4 levels were slightly but significantly lower in winter, and TSH levels and delta TSH at 30 minutes in the TRH tests were significantly higher. In the controls, there were no significant differences between summer and winter in these values. These findings suggest that the dose required for replacement of thyroid hormone in patients with hypothyroidism may be higher in winter than in summer.     

胃癌组织H-ras基因点突变与预后的关系

目的:胃癌发生发展的分子基础仍不甚明了,为了明确H—ras点突变在胃癌发生发展中的作用,本研究对胃癌组织H—ras点突变进行检测。方法:采用多聚酶链延伸反应—限制性片段长度多态性分析法(PCR—RFLP)对88例福尔马林液固定、石蜡包埋胃癌组织H—ras第12位和61位密码子点突变作了检测,并对点突变与肿瘤生物学行为及预后的关系进行分析。结果:H—ras总突变率为14.8％(13/88),点突变的发生与肿瘤将膜浸润,淋巴结转移、临床分期及术后生存期密切相关。结论:检测胃癌组织H—ras基因点突变有助于判断胃癌患者的预后。     

Long-term effects of captopril on passive sodium permeability and contractility in vascular smooth muscles of spontaneously hypertensive rats

Long-term effects of captopril on passive sodium permeability and cellular sodium concentration in the aorta of spontaneously hypertensive rats were examined in terms of contractile properties of the muscle. In cold lithium solution, cellular sodium in the aorta isolated from spontaneously hypertensive rats leaked more rapidly than did that isolated from Wistar Kyoto rats (WKY), suggesting an increased sodium permeability in the aorta of spontaneously hypertensive rats. Six weeks of treatment with captopril reduced the increased sodium permeability after hydralazine had failed. Inhibition of the sodium pump by incubating the aorta in potassium-free solution produced a slowly developing contraction which was associated with accumulation of cellular sodium. Both the magnitude of contraction and the accumulation of sodium during exposure to potassium-free solution for 1 hour were significantly less in the aorta isolated from spontaneously hypertensive rats treated with captopril compared with those from control spontaneously hypertensive rats. These data suggest that after prolonged administration, captopril alters the abnormal sodium permeability of vascular smooth muscle in spontaneously hypertensive rats and that the restoration of normal permeability reduces vascular tone.     

P8 expression is induced in acinar cells during chronic pancreatitis

The p8 gene is barely expressed in the normal pancreas, but is overexpressed in acute pancreatitis. To elucidate the dynamic expression of p8 mRNA and its significance in the course of chronic pancreatitis, we investigated the p8 expression in spontaneous chronic pancreatitis in the WBN/Kob rat as well as in humans and arginine-treated rat pancreatic acinar AR4-2J cells. p8 mRNA was significantly increased at 12 weeks when chronic pancreatitis first appeared in the WBN/Kob rats. p8 was immunolocalized in the acinar cell nuclei. Acinar cell apoptosis was significantly increased at 12 and 20 weeks in the WBN/Kob rats. In AR4-2J cells, p8 mRNA was significantly induced at 4 hr after arginine addition. Apoptosis of AR4-2J cells was not increased during the strong expression of p8 mRNA. These results suggest that p8 is induced in the acinar cells during chronic pancreatitis as the self-defence mechanism against proapoptotic insults.     

缺氧诱导因子-1α和p53在原发性肝癌中的表达及其与临床病理参数的相关性

缺氧诱导因子(HIF)-1α在大多数正常组织中检测不到,在缺氧、癌基因激活、抑癌基因失活、生长因子等因素的刺激下,HIF-1 α与另一亚单位HIF-1 β结合,作用于结构基因的调控序列,促进下游基因转录,使组织细胞对缺氧产生适应性调节.