Comparison of three models of neuropathic pain in mice using a new method to assess cold allodynia: The double plate technique

The recent identification of receptors sensitive to cold stimuli increased the significance of using mice to study cold allodynia, one of the important features of neuropathic pain. However, commonly used techniques (simple cold plate and acetone technique) may be inappropriate to study cold allodynia in mice because of problems of interpretation. We have developed a new method for assessing aversion to a cold non-noxious stimulus. It consists of calculating the time that mice spend on a non-noxious cold plate during their explorative behavior versus a thermoneutral one. We used three different models of neuropathic pain: chronic constriction injury of the sciatic nerve (CCI), partial sciatic nerve ligation (PSL) and chronic constriction of the saphenous nerve (CCS) with their respective sham groups and naive animals to assess the double plate in comparison to the acetone drop technique. All operated mice displayed cold allodynia with both methods. The response to acetone and the time spent on the cold plate were correlated (r = −0.93) and we also showed that the CCI mice were more sensitive to cold. Pharmacological validation of this technique showed that CCI induced cold allodynia was alleviated by gabapentin. In conclusion, the double plate technique provides a new, relevant method for assessing cold allodynia in mice. The advantages and drawbacks with the other techniques are discussed.     

A fatal poisoning case of acetone cyanohydrin and citalopram

Acetone cyanohydrin (ACH) is a readily available source of cyanide and is widely used in basic and applied sciences. In toxicology, ACH is classified as extremely hazardous as it readily decomposes on contact with water, with the potential rapid release of highly toxic hydrogen cyanide (HCN). We report the case of a young woman found dead from the intentional ingestion of ACH and citalopram, an antidepressant of the selective serotonin reuptake inhibitor class. The autopsy findings included bright reddish-purple hypostasis and mild pulmonary edema. As ACH can decompose to acetone and HCN, we quantified the concentration of each compound and thiocyanate separately in various body fluids and organs and determined their whole-body distributions by using gas chromatography–mass spectrometry (GC–MS). We observed high concentrations of both acetone and cyanide in the blood (0.63 mg/mL and 17.99 mM, respectively) and gastric contents (9.76 mg/mL and 472.44 mM). The whole-body distributions of acetone and cyanide were similar (i.e., the concentration of each compound was the highest in the lung, followed by the heart, and then the liver). Our results suggest that not only the route of administration but also the dose taken could greatly affect the body distributions of cyanide in humans. In addition, as toxicological screening detected citalopram, which was not prescribed to the deceased, we performed a chiral analysis by using liquid chromatography–tandem mass spectrometry (LC–MS/MS). We determined that only (S)-citalopram was ingested antemortem; its concentration was 0.36 μg/mL, which is in the toxic range.     

Effect of ascorbic acid,ethanol and acetone on adhesion between the treated fiber posts and composite resin cores

PURPOSE

The aim of the present study was to assess the effect of ascorbic acid, ethanol and acetone on microtensile bond strength between fiber posts pre-treated with hydrogen peroxide and composite resin cores.

MATERIALS AND METHODS

Twenty four fiber posts were pre-treated with 24% hydrogen peroxide and divided into 4 groups as follows: G1: no treatment, as control group; G2: treatment with 10% ascorbic acid solution for 5 minutes; G3: treatment with 70% ethanol solution for 5 minutes; and G4: treatment with 70% acetone solution for 5 minutes. Each fiber post was surrounded by a cylinder-shaped polyglass matrix which was subsequently filled with composite resin. Two sections from each sample were selected for microtensile test at a crosshead with speed of 0.5 mm/min. Statistical analyses were performed using one-way ANOVA and a post hoc Tukey HSD test. Fractured surfaces were observed under a stereomicroscope at ×20 magnification. The fractured surfaces of the specimens were observed and evaluated under a SEM.

RESULTS

Means of microtensile bond strength values (MPa) and standard deviations in the groups were as follows: G1: 9.70±0.81; G2: 12.62±1.80; G3: 16.60±1.93; and G4: 21.24±1.95. G4 and G1 had the highest and the lowest bond strength values, respectively. A greater bond strength value was seen in G3 compared to G2. There were significant differences between all the groups (P<.001). All the failures were of the adhesive mode.

CONCLUSION

Application of antioxidant agents may increase microtensile bond strength between fiber posts treated with hydrogen peroxide and composite cores. Acetone increased bond strength more than ascorbic acid and ethanol.     

头孢噻肟酸中残留溶媒的测定

目的:建立一种气相色谱法同时测定原料药头孢噻肟酸中有机溶剂丙酮、二氯甲烷、乙酸乙酯残留量的方法。方法:采用外标法顶空自动进样,在非极性弹性毛细管柱上进行分离,效果良好。结果:平均回收率:丙酮100．3％-103．5％;二氧甲烷100．9％-101．4％;乙酸乙酯98．6％-101．5％,变异系数:丙酮2．1％,二氧甲烷2．0％,乙酸乙酯1．1％。结论:方法重现性好,定量准确,便于操作。     

顶空-气相色谱法测定穿心莲内酯中有机溶剂残留量

目的：建立穿心莲内酯中有机溶剂残留量顶空毛细管气相色谱法测定方法.方法：色谱柱为CP-624毛细管柱（30m×0.32 mm×1.8μm）,N,N-二甲基甲酰胺为溶解介质,FID检测器.气化室温度200℃,检测器温度300℃,载气为氮气.柱温采取程序升温：起始温度为60 ℃,保持10min,以50℃·min^-1的速率升温至210℃,保持6 min.结果：穿心莲内酯中乙醇内酮及三氯甲烷得到完全分离,3批样品测定结果符合规定.结论：该方法简单、灵敏、准确.     

Sex differences in the toxicokinetics of inhaled solvent vapors in humans 2. 2-propanol

The aim of this study was to evaluate possible sex differences in the inhalation toxicokinetics of 2-propanol vapor. Nine women and eight men were exposed on different occasions for 2 h during light physical exercise (50 W) to 2-propanol (350 mg/m3) and to clean air (control exposure). The level corresponds to the Swedish occupational exposure limit. 2-Propanol and its metabolite acetone were monitored up to 24 h after exposure in exhaled air, blood, saliva, and urine by headspace gas chromatography. Body fat and lean body mass were estimated from sex-specific equations using bioelectrical impedance, body weight, height, and age. Genotypes were determined by PCR-based assays for alcohol dehydrogenase and cytochrome P450 2E1 (CYP2E1). The CYP2E1 phenotype was assessed by the 2-h plasma 6-hydroxychlorzoxazone/chlorzoxazone metabolic ratio in vivo. The toxicokinetic profile in blood was analyzed using a one-compartment population model. The following sex differences were significant at the p = 0.05 level (Student's t test). The respiratory uptake was lower and the volume of distribution smaller in females. The women had a slightly shorter half-time of 2-propanol in blood and a higher apparent total clearance when corrected for body composition. However, women reached approximately four times higher 2-propanol levels in exhaled air at 10-min postexposure and onward. Acetone in blood was markedly higher in females than in males in the control experiment and slightly higher following exposure to 2-propanol. A marked sex difference was that of a 10-fold higher in vivo blood:breath ratio in men, suggesting sex differences in the lung metabolism of 2-propanol. The most marked sex difference was that of salivary acetone, for which an approximately 100-fold increase was seen in women, but no increase in men, after exposure to 2-propanol compared to clean air. The toxicokinetic analysis revealed no significant differences in toxicokinetics between subjects of different metabolic genotypes or phenotypes. In conclusion, the study indicates several sex differences in the inhalation toxicokinetics of 2-propanol. Most of these differences are consistent with anatomical differences between women and men. However, body build can not explain the sex differences in 2-propanol levels in expired air and acetone in saliva.     

气相色谱-质谱法萃取丙酮呼吸试验在糖尿病中的初步应用

目的探讨气相色谱-质谱(GC-MS)法萃取丙酮呼吸试验用于糖尿病(DM)检测。方法按照美国糖尿病协会(ADA)推荐的新DM诊断标准随机选取15例2型DM患者,空腹8 h以上,采用Ted lar气袋收集呼出气体,气体样品在30 m in内进行分析。采用GC-MS和固相微萃取(SPME)方法,通过聚二甲基硅烷/二乙烯基苯(PDMS-DVB)纤维萃取呼出气体的丙酮,并迅速与五氟苯基羟胺的氢氯化物(PFBHA)在纤维上反应,在数十秒内生成丙酮肟,由GC分析测定肟的含量。结果DM患者呼出气体中丙酮含量均高于1.71 ppmv,而在对照组中测定值均低于0.77 ppmv。结论采用GC-MS和SPME法是测定人体呼吸中丙酮含量敏感而有效的方法,可能尝试作为DM全新检测和监测手段。     

气相色谱法测定洛索洛芬钠中丙酮的残留量

目的建立用气相色谱法测定洛索洛芬钠中丙酮的残留量。方法采用外标法毛细管气相色谱法,氢火焰离子化检测器（FID）,以N,N二甲基甲酰胺（DMF）为溶剂,以5%苯基聚硅氧烷熔融石英毛细管柱（SPB-5）（30m×0.53mm×1.5μm）为色谱柱;柱温60℃维持5min,以40℃/min的速率升温至180℃,维持4min;以高纯氮气为载气,流速3.6mL.min^-1;分流比20∶1;进样口温度180℃;检测器温度230℃;进样量1μL。结果丙酮与峰面积呈良好的线性关系,加样回收率为101.2%,RSD为1.8%。结论方法简便,准确,可有效控制洛索洛芬钠产品质量。     

气相色谱法同时检测A群脑膜炎球菌多糖疫苗中的残留乙醇和丙酮

目的 建立可同时检测A群脑膜炎球菌多糖疫苗等生物制品中的残留乙醇和丙酮的毛细管气相色谱法.方法 通过实验选择DB-FFAP型色谱柱为分离柱,气相色谱条件设置为:进样口温度200℃、检测器温度250 ℃、柱温60℃、进样体积1 μl、分流比10:1、载气(氮气)流速2.0 ml/min.在已确定的色谱条件下,对乙醇和丙酮进行定位及最低检出限和线性范围测定,重复性和准确性实验及样品测定同时进行.结果 在本色谱条件下,乙醇和丙酮得到完全分离,最低检出限分别为0.196和0.102mg/L,每种溶剂的线性关系均良好,相关系数均为0.9997.此法的重复性良好,乙醇和丙酮的平均加样回收率分别为102.8%和102.9%.结论 此法适合同时检测A群脑膜炎球菌多糖疫苗中的残留乙醇和丙酮.