Muscarinic regulation of intracellular signaling and neurosecretion in gonadotropin-releasing hormone neurons

Agonist activation of cholinergic receptors expressed in perifused hypothalamic and immortalized GnRH-producing (GT1-7) cells induced prominent peaks in GnRH release, each followed by a rapid decrease, a transient plateau, and a decline to below basal levels. The complex profile of GnRH release suggested that acetylcholine (ACh) acts through different cholinergic receptor subtypes to exert stimulatory and inhibitory effects on GnRH release. Whereas activation of nicotinic receptors caused a transient increase in GnRH release, activation of muscarinic receptors inhibited basal GnRH release. Nanomolar concentrations of ACh caused dose-dependent inhibition of cAMP production that was prevented by pertussis toxin (PTX), consistent with the activation of a plasma-membrane Gi protein. Micromolar concentrations of ACh also caused an increase in phosphoinositide hydrolysis that was inhibited by the M1 receptor antagonist, pirenzepine. In ACh-treated cells, immunoblot analysis revealed that membrane-associated G(alpha q/11) immunoreactivity was decreased after 5 min but was restored at later times. In contrast, immunoreactive G(alpha i3) was decreased for up to 120 min after ACh treatment. The agonist-induced changes in G protein alpha-subunits liberated during activation of muscarinic receptors were correlated with regulation of their respective transduction pathways. These results indicate that ACh modulates GnRH release from hypothalamic neurons through both M1 and M2 muscarinic receptors. These receptor subtypes are coupled to Gq and Gi proteins that respectively influence the activities of PLC and adenylyl cyclase/ion channels, with consequent effects on neurosecretion.     

Diabetic neuropathic cachexia: report of a recurrent case

We present the case of an 18-year-old woman with a shortened right index finger. The digit was stabilized and lengthened a total of 18 mm by external fixation and iliac bone grafting. A distal interphalangeal fixed flexion deformity of 60 degrees was corrected with external fixation and intermedullary wiring.     

Combination of enalapril and low-dose thiazide reduces normoalbuminuria in essential hypertension

OBJECTIVE: To examine the effect of the combination of enalapril with a very low dose of hydrochlorothiazide versus atenolol on urinary albumin excretion in normoalbuminuric patients with mild to moderate essential hypertension. A secondary objective was to compare the effects of the two regimens in patients with different levels of albuminuria. DESIGN: A 12 weeks, randomized, double-blind, double-dummy, multicenter, comparative study with two parallel groups. SETTING: General practices in Denmark and Finland. PATIENTS: The subjects comprised 174 patients with mild to moderate essential hypertension, normal serum creatinine and no proteinuria. INTERVENTIONS: Enalapril/hydrochlorothiazide (20/6 mg) daily or atenolol (50 mg) daily. MAIN OUTCOME MEASURES: Urinary albumin: creatinine ratio and blood pressure. RESULTS: At baseline, normoalbuminuria was found in 74 and 85 patients in the enalapril/hydrochlorothiazide and atenolol groups, respectively. Blood pressure was reduced similarly by both treatments. The ratio of urinary albumin to creatinine in normoalbuminuric patients was significantly reduced during treatment with enalapril/hydrochlorothiazide at 20/6 mg (from geometic mean x/divided by antilog SD of 0.53 x/divided by 1.77 to 0.47 x/divided by 1.58 mg/mmol, P=0.02) but was unchanged during atenolol treatment (0.55 x/divided by 1.74 and 0.58 x/divided by 1.87 mg/mmol). The difference between the two treatments was statistically significant (P=0.03) and was predominantly achieved through a reduction of albuminuria in the upper-normal range during enalapril/hydrochlorothiazide treatment. CONCLUSIONS: Therapy with enalapril/hydrochlorothiazide at 20/6 mg and atenolol at 50 mg once daily reduced blood pressure similarly in patients with essential hypertension. Suppression of urinary albumin excretion within the normoalbuminuric range was observed during treatment with enalapril/hydrochlorothiazide at 20/6 mg.     

Use of nonoxynol-9 and changes in vaginal lactobacilli

The conformation of lens crystallins in vivo or in a highly concentrated solution is not well established. Most studies were carried out in dilute solutions in which protein-protein interaction is minimal. In order to see whether there is conformational change (tertiary and secondary structures) when crystallin solutions are brought to high concentrations, we have performed the following molecular spectroscopic measurements: circular dichroism (CD) and Fourier transform infrared (FTIR). Near-UV CD measurements showed a more than two-fold increase in CD intensity (molar ellipticity) for the total water-soluble (WS) protein from young calf lens nucleus in a highly concentrated solution (> 300 mg/ml in a 0.01-mm cell), when compared with a dilute solution (1000-fold dilution in a 10-mm cell). The individual crystallins in concentrated solutions also showed an increase in CD intensity, but of different magnitude: alpha-crystallin > beta-crystallin > gamma-crystallin. The increased CD indicates that lens crystallins are in a more compact structure in highly concentrated solutions; they likely undergo a transition from a mobile to an immobile state. Change in near-UV CD usually is caused by restricted mobility of aromatic side groups, particularly Trp. The transition involves not only a change in protein tertiary and/or quaternary structure, but also in protein backbone structure. The change of protein backbone structure was drawn from FTIR measurements. FTIR spectra, sensitive to the secondary structure in the amide I region, could be measured for a highly concentrated solution for which far-UV CD measurement is not feasible. The secondary structure that showed prominent change for alpha-crystallin in a highly concentrated solution was beta-conformation: increase in beta-turn with a concomitant decrease of alpha-helix structure.     

Hypothermia during or after severe perinatal asphyxia prevents increase in cyclic GMP-related nitric oxide levels in the newborn rat striatum

The striatum is rich in nitric oxide synthase (NOS). It is present in a dense fiber network and in a few medium-sized non-spiny interneurons. Previous work showed chronic overexpression of NOS in the rat striatum after a severe perinatal asphyctic (SPA) insult. This was prevented by hypothermia. We investigated whether the overexpression of NOS was accompanied by increased NOS activity. As nitric oxide (NO) is a potent activator of the soluble isoform of guanylyl cyclase, we measured striatal 3',5'-cyclic monophosphate (cyclic GMP) synthesis in 10-day-old (P10) rat pups that were subjected to SPA during normothermia or hypothermia during or after the insult. Cyclic GMP levels in striatal tissue from control pups were approximately 25.8 pmol/mg protein and in the SPA group approximately 38.1 pmol/mg protein (p<0.01). Hypothermia, during as well as after insult, prevented this increase of cyclic GMP. Nomega-nitro-L-arginine (L-NAME) (0.1 mM) decreased cyclic GMP levels in control, SPA and hypothermia treated pups to similar low levels (approximately 8% of level without L-NAME). Sodium nitroprusside (SNP) stimulated cyclic GMP showed no differences between the four groups. This indicates that high cyclic GMP levels in the striatum of rats subjected to SPA are caused by increased NOS activity. Hypothermia after an asphyctic insult could be a promising treatment.     

Use of a cysteine proteinase from Carica candamarcensis as a protective agent during DNA extraction

We describe the use of a plant cysteine proteinase isolated from latex of Carica candamarcensis as a protective agent during isolation of bacterial DNA following growth in culture of these cells. Between 100 to 720 units of proteinase (1 microgram = 6 units) afforded good DNA protection when incubated with various kinds of microorganisms. Agarose gel electrophoresis showed that the resulting DNA was similar in size to DNA preparations obtained by treatment with proteinase K. The viability of the resulting material was checked by PCR amplification using species-specific primers. After standing at room temperature (25 degrees C) for 35 days, the enzyme lost 10% of its initial activity. The enzyme stability and good yield of DNA suggest the use of this proteinase as an alternative to proteinase K.     

有助于无线探头测量感应式电源的低功耗电压-频率转换器

为执行长期监视任务的便携式遥测系统供电．向人们提出了有趣的设计挑战。电池不适合于某些关键性应用，且在这些环境中，设计人员一般用无线感应链路来传输功率与数据。感应链路由一个驱动固定初级线圈的射频发射器与一个为便携式装置提供电源的松耦合次级线圈组成。对设计工程师来说．测量发射功率相当重要．因为它会限制设计人员可包含至便携式装置中的电路数量。但不幸的是，传统测试设备不适合执行该任务．     

Activation of the ATM kinase by ionizing radiation and phosphorylation of p53

The p53 tumor suppressor protein is activated and phosphorylated on serine-15 in response to various DNA damaging agents. The gene product mutated in ataxia telangiectasia, ATM, acts upstream of p53 in a signal transduction pathway initiated by ionizing radiation. Immunoprecipitated ATM had intrinsic protein kinase activity and phosphorylated p53 on serine-15 in a manganese-dependent manner. Ionizing radiation, but not ultraviolet radiation, rapidly enhanced this p53-directed kinase activity of endogenous ATM. These observations, along with the fact that phosphorylation of p53 on serine-15 in response to ionizing radiation is reduced in ataxia telangiectasia cells, suggest that ATM is a protein kinase that phosphorylates p53 in vivo.     

Preconditioning of isolated rabbit cardiomyocytes: no evident separation of induction, memory and protection

Cardiomyocytes isolated from rabbit hearts were preconditioned in vitro by 10 min of ischemia or treatment with 100 microM adenosine. Protection was assessed as average integrated mortality following osmotic swelling and determination of viability by trypan blue exclusion over 60-180 min ischemia. Repetitive sub-maximal stimulations with 1 microM adenosine amplified the protective response. Treatment with adenosine only at the onset of prolonged ischemia afforded a dose-dependent protection. The PKC inhibitor calphostin C (500 nm) blocked preconditioning and, when added during ischemic incubation of non-preconditioned cells, significantly increased injury. The memory of adenosine-induced preconditioning decayed over a 60 min post-incubation period. Light activation of calphostin C initially added to preconditioned ischemic cells in the dark indicated that a 10 min period of PKC activity at the onset of ischemia affords full protection. The reversible PKC inhibitors chelerythrine (5 microM) or staurosporine (100 nM) added only to bracket induction of ischemia, reduced but did not abolish protection. Protection was abolished when either drug was present during induction and a subsequent 30 min post-incubation period. Staurosporine included during initiation and post-incubation but washed out in the final 5 min of post-incubation allowed significant protection to occur. It is concluded that a single adenosine receptor-stimulation induces protection as it preconditions, and PKC activity appears to be required for both induction and protection. Memory may reside in post-receptor amplification of an initial protective response.