Peripheral catecholamine release by α-latrotoxin in the rat

Summary Intraarterial injection of -latrotoxin (LTx), the major toxin of the black widow spider (Latrodectus mactans tredecimguttatus) venom, into carotid catheterized rats, induced prompt and marked rises in plasma adrenaline and noradrenaline concentrations, indicating that the toxin stimulates catecholamine release from both the adrenal medulla and sympathetic nerve terminals. Pretreatment with the ganglionic blocker chlorisondamine greatly reduced the plasma adrenaline response to LTx but had almost no effect on the noradrenaline response, indicating that LTx-stimulation of sympathetic nerve terminals is direct, whereas catecholamine release from the adrenal medulla is probably mediated by preganglionic release of acetylcholine. In vitro, LTx induced a dose-dependent release of ³H-noradrenaline from rat irides preincubated with this radioactive amine and this effect was not changed by chlorisondamine plus atropine. By contrast, the toxin had no effect on ³H-noradrenaline release from suspensions of cultured rat chromaffin cells. Specific, high affinity binding of ¹²⁵I-LTx in iris and adrenal medulla homogenates was found to be exceedingly low, suggesting that it might be restricted to nerve terminals. No ¹²⁵I-LTx binding was seen nor could any effect of the toxin on ¹⁴C-5-hydroxytryptamine release be found in rat blood platelet preparations. LTx binding and its amine releasing effect seem, therefore, to be specific for neurons and absent from other cells, even those, like adrenomedullary cells and blood platelets, which share with neurons their origin and/or other important characteristics.     

Is Drug Use by the Elderly with Cognitive Impairment Influenced by Type of Dementia?

Patterns of drug use among the elderly vary greatly depending on level of cognitive function, yet no systematic evaluation of drug use by type of dementia has been performed. We compared patterns of drug use among patients with Alzheimer's disease (AD) and vascular dementia (VaD) to examine their relation to cognitive impairment. We used a population-based data set with over 350,000 residents admitted between 1992 and 1995 to all Medicare-Medicaid-certified nursing homes in five states. After excluding patients with a history of mental disorders or retardation, we identified 23,073 patients age 65 years and over with a diagnosis of AD and 76,087 with VaD. We examined over 350 resident data items (demographic, diagnostic, clinical, treatment) collected with the federally mandated Minimum Data Set, drug data (brand name, dosage, route and frequency of administration for all drugs), and Medicare hospital claims. Cognitive status was measured with a 7-point cognitive performance scale. Estimates of drug use were adjusted for age, gender, race, and prevalence of respective disease. Patients with AD were younger and had more severe cognitive impairment than those with VaD. The latter had more comorbid clinical conditions (3.1 +/- 1.9 vs 2.3 +/- 1.7 for patients with AD) and received a greater number of total drugs (6.1 +/- 4.6 vs 5.3 +/- 4.3). Overall use of cardiovascular, anti-Parkinson, pulmonary, antineoplastic, and nutritional agents was less frequent among patients with AD than those with VaD. Results were consistent across different levels of cognitive impairment. Thus, patients with AD have fewer associated diseases and appear to be less intensively medically treated.     

Enhanced gene transfection efficiency by low-dose 25 kDa polyethylenimine by the assistance of 1.8 kDa polyethylenimine

Gene therapy is a promising strategy for treatments of various diseases. Efficient and safe introduction of therapeutic genes into targeted cells is essential to realize functions of the genes. High-molecular-weight polyethylenimines (HMW PEIs) including 25?kDa branched PEI and 22?kDa linear PEI are widely used for in vitro gene transfection. However, high-gene transfection efficiency is usually accompanied with high cytotoxicity, which hampers their further clinical study. On the contrary, low-molecular-weight polyethylenimines (LMW PEIs) such as 1.8?kDa PEI and 800?Da PEI show good biocompatibility but their applications are limited by the poor DNA condensation capability. In this study, we find that 1.8?kDa PEI, but not 800?Da PEI combined with low-dose 25?kDa PEI could significantly promote gene transfection with low cytotoxicity. Plasmids encoding enhanced green fluorescence protein (EGFP) were delivered by the combined PEI and gene transfection efficiency was evaluated by microscopic observation and flow cytometry. Parameters including concentrations of 25?kDa PEI and 1.8?kDa PEI and preparation ways were further optimized. This study presents an efficient and safe combined PEI-based non-viral gene delivery strategy with potential for in vivo applications.     

How does the common core to the harm experienced by affected family members vary by relationship,social and cultural factors?

Abstract

This paper takes an international perspective on the harm to close family members caused by addiction. It draws on data collected by the Addiction and the Family International Network (AFINet), England, and their colleagues in other countries. It includes qualitative data based on semi-structured interviews in Mexico, England, Australia (an Indigenous sample), Nigeria, and India; quantitative data based on the use of a standard set of questionnaires specifically designed or chosen for use with family members affected by addiction problems collected in Mexico, England, Italy, Brazil and the USA. The results are interpreted to suggest that, although there is a common core to the harm experienced by all affected family members (AFMs), the family harm is variable, dependent in important ways on relationship, social and cultural factors. Specifically, it is hypothesised that AFMs experience greater coping difficulty and higher levels of strain under conditions of: greater accumulated burden; a family position of structural subordination and dependence; and lack of good quality social support.     

Caffeine inhibits antinociception by acetaminophen in the formalin test by inhibiting spinal adenosine A₁ receptors

The present study examined effects of caffeine on antinociception by acetaminophen in the formalin test in mice. It demonstrates that caffeine 10mg/kg inhibits antinociception produced by acetaminophen 300 mg/kg i.p. against phase 2 flinches. Chronic administration of caffeine in the drinking water (0.1, 0.3g/l) for 8 days also inhibits the action of acetaminophen. The selective adenosine A(1) receptor antagonist DPCPX 1mg/kg i.p. mimics the action of caffeine, but the selective adenosine A(2A) receptor antagonist SCH58261 3mg/kg i.p. does not. While acetaminophen produced the same effect in mice that were +/+, +/- and -/- for adenosine A(1) receptors, inhibition of antinociception by caffeine was seen only in +/+ and +/- mice. A higher dose of caffeine, 40 mg/kg, produced an intrinsic antinociception against formalin-evoked flinches, an effect also seen when caffeine was administered intrathecally. SCH58261 30 nmol, but not DPCPX 10 nmol, also produced antinociception when administered intrathecally indicating involvement of adenosine A(2A) receptors in spinal antinociception. Caffeine reversal of acetaminophen results from actions in the spinal cord, as intrathecal DPCPX 10 nmol inhibited antinociception by systemic acetaminophen; this was also observed in +/+ but not in -/- adenosine A(1) receptor mice. We propose that spinal adenosine A(1) receptors contribute to the action of acetaminophen secondarily to involvement of descending serotonin pathways and release of adenosine within the spinal cord. Inhibition of acetaminophen antinociception by doses of caffeine relevant to dietary human intake levels suggests a more detailed consideration of acetaminophen-caffeine interactions in humans is warranted.     

Increase by α-adrenolytic drugs of acetylcholine release evoked by field stimulation of the guinea-pig ileum

Summary The release of acetylcholine evoked by field stimulation of the guinea-pig ileum (3 Hz) is increased by yohimbine and tolazoline but not affected by phentolamine. It is proposed that yohimbine and tolazoline by blocking -adrenoceptors of the cholinergic nerves abolish the inhibition caused by endogenous noradrenaline, and thus facilitate the output of acetylcholine.     

Why does the inner-helix mutation A413C double the stoichiometry of Kv1.3 channel block by emopamil but not by verapamil?

hKv1.3 channels in lymphocytes are targets for the chemotherapy treatment of autoimmune diseases. Phenylalkylamines block Kv1.3 channels by poorly understood mechanisms. In the inactivation-reduced mutant H399T, the second mutation A413C in S6 substantially decreases the potency of phenylalkylamines with a para-methoxy group at the phenylethylamine end, whereas potency of phenylalkylamines lacking this group is less affected. Intriguingly, completely demethoxylated emopamil blocks mutant H399T/A413C with a 2:1 stoichiometry. Here, we generated a triple mutant, H399T/C412A/A413C, and found that its emopamil-binding properties are similar to those of the double mutant. These data rule out disulfide bonding Cys412-Cys413, which would substantially deform the inner helix, suggest a clash of Cys413 with the para-methoxy group, and provide a distance constraint to dock phenylalkylamines in a Kv1.2-based homology model. Monte Carlo minimizations predict that the verapamil ammonium group donates an H-bond to the backbone carbonyl of Thr391 at the P-loop turn, the pentanenitrilephenyl moiety occludes the pore, whereas the phenylethylamine meta- and para-methoxy substituents approach, respectively, the side chains of Met390 and Ala413. In the double-mutant model, the Cys413 side chains accept H-bonds from two emopamil molecules whose phenyl rings fit in the hydrophobic intersubunit interfaces, whereas the pentanenitrilephenyl moieties occlude the pore. Because these interfaces are unattractive for a methoxylated phenyl ring, the ammonium group of respective phenylalkylamines cannot approach the Cys413 side chain and binds at the focus of P-helices, whereas the para-methoxy group clashes with Cys413. Our study proposes an atomistic mechanism of Kv1.3 block by phenylalkylamines and highlights the intra- and intersubunit interfaces as ligand binding loci.     

Increased psychotropic drug consumption by children in the Netherlands during 1995–2001 is caused by increased use of methylphenidate by boys

Objective The aim of the study was to determine the changes in consumption of psychotropic drugs by children aged less than 18 years during the years 1995 to 2001 in the Netherlands.Methods The year prevalence of antipsychotics, benzodiazepines, antidepressants and psychostimulants for boys and girls under 18 years was determined using electronic pharmacy dispensing records obtained from the PHARMO database.Results The overall prevalence of psychotropic drugs increased from 11.1 per 1000 in 1995 to 22.9 per 1000 in 2001. This increase could almost completely be attributed to the increase in the use of psychostimulants, i.e. methylphenidate, which increased from 1.7 per 1000 children in 1995 to 10.0 per 1000 in 2001. For the other psychotropic drugs, no or only a small increase was seen. For both boys and girls, the use of psychostimulants was highest in the age group of 5–14 years.Conclusion During the years 1995–2001, the consumption of psychotropic drugs by children in the Netherlands has more than doubled. This increase could largely be attributed to an increased use of the psychostimulant methylphenidate by boys of the age 5–14 years.     

Effect of ECR on the Expression of Tau from the Brain of the Mice Induced by Overload Aluminum Salt

Aim: To study the effect of Ecdysterone (ECR) on the expression of Tau from the cerebral cortice and hippocampus and behaviors in passive avoidance reaction and spatial discrimination of the mice induced by overload aluminum salt.Methods Fourty-five NIH mice were randomly divided into five groups, the control group, the model group, the treated     

Effects of the administration of miconazole by different routes on the biomarkers of the “steroidal module” of the Athlete Biological Passport

This article reports the results obtained from the investigation of the influence of miconazole administration on the physiological fluctuation of the markers of the steroid profile included in the “steroidal module” of the Athlete Biological Passport. Urines collected from male Caucasian subjects before, during, and after either systemic (i.e., oral and buccal) or topical (i.e., dermal) treatment with miconazole were analyzed according to validated procedures based on gas chromatography coupled to tandem mass spectrometry (GC–MS/MS) (to determine the markers of the steroid profile) or liquid chromatography coupled to MS/MS (LC–MS/MS) (to determine miconazole urinary levels). The results indicate that only after systemic administration, the markers of the steroid profile were significantly altered. After oral and buccal administration, we have registered (i) a significant increase of the 5α-androstane-3α,17β-diol/5β-androstane-3α,17β-diol ratio and (ii) a significant decrease of the concentration of androsterone, etiocholanolone, 5β-androstane-3α,17β-diol, and 5α-androstane-3α,17β-diol and of the androsterone/etiocholanolone, androsterone/testosterone, and 5α-androstane-3α,17β-diol/epitestosterone ratios. Limited effects were instead measured after dermal intake. Indeed, the levels of miconazole after systemic administration were in the range of 0.1–12.5 μg/ml, whereas after dermal administration were below the limit of quantification (50 ng/ml). Significant alteration started to be registered at concentrations of miconazole higher than 0.5 μg/ml. These findings were primarily explained by the ability of miconazole in altering the kinetic/efficacy of deglucuronidation of the endogenous steroids by the enzyme β-glucuronidase during the sample preparation process. The increase of both incubation time and amount of β-glucuronidase was demonstrated to be effective countermeasures in the presence of miconazole to reduce the risk of uncorrected interpretation of the results.     

Risk assessment by physicians and by the poison center: are nondrug exposures handled too actively?

BACKGROUND: The study was intended to evaluate the possible impact of poison center advice on physicians' treatment and referral of nondrug exposures. METHODS: Doctors seeking advice on nondrug poisoning were asked for their management plan before any recommendations were given. The proportions of cases in different treatment and referral categories were compared to the poison center recommendations. Rate ratios were used as effect measure. RESULTS: A total of 175 cases were included in the study. For 90% of these, the exposure was estimated by the poison center to be of no or minor risk. The inquiring physicians had intended to treat 43 more cases than the poison center recommended, rate ratios: 1.6 (95% CI: 1.3-2.0). The most marked difference wasfor treatment by gastrointestinal decontamination, rate ratios: 5.0 (95% CI: 2.5-9.8). For referral, 42 more cases would have been observed in a stationary hospital unit, rate ratios: 2.3 (95% CI: 1.6-3.3) and 28 excess cases would have been observed in an outpatientfacility, rate ratios: 2.0 (95% CI: 1.3-1.6). A more active attitudefor treatment and referral by the inquirers was independently associated with patients < or =14 years of age, lack of symptoms at presentation, and insignificant exposures. CONCLUSIONS: Doctors seeking advice on the management of nondrug poisoning intended to treat and refer to health care facilities more actively than recommended by the poison center. The tendency was most pronouncedfor children exposed to substances of minor toxicological significance and treatment with gastrointestinal decontamination.     

Drug-mediated toxicity: illuminating the 'bad' in the test tube by means of cellular assays?

Health problems are rising worldwide, be it as a consequence of lifestyle and longevity in increasingly affluent societies or due to a sharp rise in bacterial antibiotic resistance. The pharmaceutical industry is caught between high rates of attrition and the rather slow pace of a historically large regulatory system for pharmacological safety. Meanwhile, the past decade has seen a tremendous evolution of the biological toolbox, most notably of cellular assays, stem-cell differentiation and organ-mimicking systems. These systems were readily adapted for lead-compound identification. However, their use as toxicological test systems is lagging behind, not least because of a lack of regulatory acceptance. This review tries to elucidate the scale of the problem and discusses the applicability of the assays currently available, with particular regard to the use of stem cells.     

Modulation of Δ9-tetrahydrocannabinol-induced hypothermia by fluoxetine in the rat

1. It has been suggested that the dose of Δ⁹-tetrahydrocannabinol (Δ⁹-THC) that induces hypothermia in the rat increases the release of brain 5-hydroxytryptamine (5-HT). In light of this, we investigated the hypothermia produced by Δ⁹-THC, and the effect the selective serotonin reuptake inhibitor fluoxetine has on this response.
2. A significant dose-dependent decrease in body temperature occurred after i.v. administration of 0.5 to 5 mg kg⁻¹ Δ⁹-THC; maximum decreases being 0.8±0.2°C to 2.9±0.3°C. This hypothermic response was attenuated by the cannabinoid CB₁ receptor antagonist SR 141716.
3. Fluoxetine (10 mg kg⁻¹ i.p.) alone caused a decrease in body temperature of 0.6±0.1°C (n=32, P<0.05) after 40 min. However, pretreatment with fluoxetine (10 mg kg⁻¹ i.p.) 40 min before Δ⁹-THC significantly reduced the Δ⁹-THC-induced hypothermia (n=7–8, P<0.05). Contrary to this antagonist-like effect, fluoxetine administered 40 min after Δ⁹-THC significantly potentiated the Δ⁹-THC-induced hypothermia, producing a maximum decrease of 3.2±0.3°C.
4. It is suggested that the effect of fluoxetine on the Δ⁹-THC-induced hypothermic response is dependent on the time of its administration relative to that of Δ⁹-THC. Pretreatment with fluoxetine increases extracellular 5-HT due to reuptake inhibition. Increased extracellular 5-HT can activate autoreceptors which may decrease serotonergic activity, thereby reducing the Δ⁹-THC-induced hypothermia. Conversely, when fluoxetine is adminstered after Δ⁹-THC, the reuptake block is thought to potentiate the already activated serotonegic system, hence potentiating the Δ⁹-THC-induced hypothermia.

     

Further study of prerequisites for the enhancement by α-adrenoceptor antagonists of the release of noradrenaline

Summary Segments of the rabbit ear artery were preincubated with (–)-³H-noradrenaline and then perfused/superfused and stimulated by transmural electrical pulses. The outflow of ³H-noradrenaline and total tritium was determined.In the first series of experiments, stimulation periods of approximately constant length (50 s) were used (cocaine 5 M present). Thirteen pulses (0.25 Hz) elicited an overflow of ³H-noradrenaline of 0.024% of tissue tritium; 26 pulses (0.5 Hz) elicited an overflow of 0.059%, and 52 pulses (1 Hz) of 0.166%. Rauwolscine 1 M did not change the overflow evoked by 13 pulses, increased that evoked by 26 pulses and increased most markedly that evoked by 52 pulses. Phentolamine 1 M decreased the overflow at 13, did not change the overflow at 26, and increased the overflow at 52 pulses. Corynanthine 1 M decreased the overflow at 13, and did not change the overflow at 26 and 52 pulses. The effect of tetraethylammonium (TEA) 100 M was opposite to that of rauwolscine; it increased most markedly the overflow evoked by 13 pulses, increased less that evoked by 26 pulses, and least the overflow at 52 pulses.In the second series of experiments, the frequency of stimulation was kept constant (2 Hz). In the absence of cocaine, 10 pulses elicited an overflow of ³H-noradrenaline of 0.023% of tissue tritium; 20 pulses elicited an overflow of 0.043%, and 40 pulses of 0.089%. Phentolamine 1 M did not change the overflow evoked by 10 pulses, increased that evoked by 20 pulses, and increased most markedly that evoked by 40 pulses. TEA 100 M increased the evoked overflow at all pulse numbers. Similar results were obtained in the presence of cocaine 5 M.The results demonstrate that the enhancement by -adrenoceptor antagonists of the release of noradrenaline depends on the biophase concentration of noradrenaline. Under the present conditions, graded increases in biophase noradrenaline concentration led to graded increases in the effect of the antagonists. A second prerequisite for the release-enhancing effect appears to be a sufficient length of the pulse train. Under the present conditions, graded increases in train length up to about 20s led to graded increases in the effect of the antagonists, even though the average biophase concentration of noradrenaline did not change with the pulse train length. This pattern of effects of the -antagonists is not shared by at least one other release-enhancing drug, namely TEA.     

Enhancing the utility of existing antibiotics by targeting bacterial behaviour?

The discovery of novel classes of antibiotics has slowed dramatically. This has occurred during a time when the appearance of resistant strains of bacteria has shown a substantial increase. Concern is therefore mounting over our ability to continue to treat infections in an effective manner using the antibiotics that are currently available. While ongoing efforts to discover new antibiotics are important, these must be coupled with strategies that aim to maintain as far as possible the spectrum of activity of existing antibiotics. In many instances, the resistance to antibiotics exhibited by bacteria in chronic infections is mediated not by direct resistance mechanisms, but by the adoption of modes of growth that confer reduced susceptibility. These include the formation of biofilms and the occurrence of subpopulations of 'persister' cells. As our understanding of these processes has increased, a number of new potential drug targets have been revealed. Here, advances in our ability to disrupt these systems that confer reduced susceptibility, and in turn increase the efficacy of antibiotic therapy, are discussed.     

Voltage-Gated Ion Channels in Nociceptors： Modulation by the cGMP-PKG pathway

目的：探讨高血糖对大鼠杏仁核点燃发展进程的影响。方法：雌性Wister大鼠戊巴比妥钠麻醉后，固定于江湾Ⅰ型脑立体定位仪上，按照Konig图谱确定大鼠左右杏仁核，坐标为前囟后3．0mm，旁开4．8mm，硬脑膜下8．8mm，将双极电极插入。动物术后恢复2周，测定后放电阈值(ADT)。然后将大鼠分为三组，糖尿病组大