鸡胚尿囊膜（HET-CAM）眼刺激替代试验对产品及原料评价的比较

目的比较鸡胚尿囊膜试验（HET-CAM）作为一种眼刺激替代方法对产品或原料的评价。方法采用HET-CAM和兔眼Draize试验方法,对19种原料和23种化妆品及家用洗涤产品眼刺激性进行检测,对体内体外试验的结果进行统计比较。结果比较体内体外试验,原料和产品的kappa系数分别为0.826,0.531;灵敏度分别为100%,81.8%;特异度分别为85.7%,77.8%。结论 HET-CAM可作为Draize试验的替代试验,HET-CAM系统更适合对单纯化学品原料进行眼刺激试验。     

Trigeminal neurons detect cellphone radiation: Thermal or nonthermal is not the question

Cellphone electromagnetic radiation produces temperature alterations in facial skin. We hypothesized that the radiation-induced heat was transduced by warmth-sensing trigeminal neurons, as evidenced by changes in cognitive processing of the afferent signals. Ten human volunteers were exposed on the right side of the face to 1 GHz radiation in the absence of acoustic, tactile, and low-frequency electromagnetic stimuli produced by cellphones. Cognitive processing manifested in the electroencephalogram (EEG) was quantitated by analysis of brain recurrence (a nonlinear technique). The theoretical temperature sensitivity of warmth-sensing neurons was estimated by comparing changes in membrane voltage expected as a result of heat transduction with membrane–voltage variance caused by thermal noise. Each participant underwent sixty 12-s trials. The recurrence variable r (“percent recurrence”) was computed second by second for the ? band of EEGs from two bilaterally symmetric derivations (decussated and nondecussated). Percent recurrence during radiation exposure (first 4 s of each trial) was reduced in the decussated afferent signal compared with the control (last four seconds of each trial); mean difference, r = 1.1 ± 0.5%, p < 0.005. Mean relative ? power did not differ between the exposed and control intervals, as expected. Trigeminal neurons were capable of detecting temperature changes far below skin temperature increases caused by cellphone radiation. Simulated cellphone radiation affected brain electrical activity associated with nonlinear cognitive processing of radiation-induced thermal afferent signals. Radiation standards for cellphones based on a thermal/nonthermal binary distinction do not prevent neurophysiological consequences of cellphone radiation.     

Caffeine Ingestion Increases Estimated Glycolytic Metabolism during Taekwondo Combat Simulation but Does Not Improve Performance or Parasympathetic Reactivation

ObjectivesThe aim of this study was to evaluate the effect of caffeine ingestion on performance and estimated energy system contribution during simulated taekwondo combat and on post-exercise parasympathetic reactivation.MethodsTen taekwondo athletes completed two experimental sessions separated by at least 48 hours. Athletes consumed a capsule containing either caffeine (5 mg∙kg^-1) or placebo (cellulose) one hour before the combat simulation (3 rounds of 2 min separated by 1 min passive recovery), in a double-blind, randomized, repeated-measures crossover design. All simulated combat was filmed to quantify the time spent fighting in each round. Lactate concentration and rating of perceived exertion were measured before and after each round, while heart rate (HR) and the estimated contribution of the oxidative (W_AER), ATP-PCr (W_PCR), and glycolytic (W_[La-]) systems were calculated during the combat simulation. Furthermore, parasympathetic reactivation after the combat simulation was evaluated through 1) taking absolute difference between the final HR observed at the end of third round and the HR recorded 60-s after (HRR_60s), 2) taking the time constant of HR decay obtained by fitting the 6-min post-exercise HRR into a first-order exponential decay curve (HRR_τ), or by 3) analyzing the first 30-s via logarithmic regression analysis (T30).ResultsCaffeine ingestion increased estimated glycolytic energy contribution in relation to placebo (12.5 ± 1.7 kJ and 8.9 ± 1.2 kJ, P = 0.04). However, caffeine did not improve performance as measured by attack number (CAF: 26. 7 ± 1.9; PLA: 27.3 ± 2.1, P = 0.48) or attack time (CAF: 33.8 ± 1.9 s; PLA: 36.6 ± 4.5 s, P = 0.58). Similarly, RPE (CAF: 11.7 ± 0.4 a.u.; PLA: 11.5 ± 0.3 a.u., P = 0.62), HR (CAF: 170 ± 3.5 bpm; PLA: 174.2 bpm, P = 0.12), oxidative (CAF: 109.3 ± 4.5 kJ; PLA: 107.9 kJ, P = 0.61) and ATP-PCr energy contributions (CAF: 45.3 ± 3.4 kJ; PLA: 46.8 ± 3.6 kJ, P = 0.72) during the combat simulation were unaffected. Furthermore, T30 (CAF: 869.1 ± 323.2 s; PLA: 735.5 ± 232.2 s, P = 0.58), HRR_60s (CAF: 34 ± 8 bpm; PLA: 38 ± 9 bpm, P = 0.44), HRRτ (CAF: 182.9 ± 40.5 s, PLA: 160.3 ± 62.2 s, P = 0.23) and HRR_amp (CAF: 70.2 ± 17.4 bpm; PLA: 79.2 ± 17.4 bpm, P = 0.16) were not affected by caffeine ingestion.ConclusionsCaffeine ingestion increased the estimated glycolytic contribution during taekwondo combat simulation, but this did not result in any changes in performance, perceived exertion or parasympathetic reactivation.     

Escape of Salmonellae from Chlorination during Ingestion by Pristionchus lheritieri (Nematoda: Diplogasterinae)

Salmonella typhi and S. wichita survived 15 min in 10 ppm free chlorine solution during ingestion by the free-living nematode, Pristionchus lheritieri, and were viable when defecated in suitable media. S. typhi and S. wichita were recovered in 13.5 and 46.6% of the trials on five different media.     

Sensory Irritation Response in Rats II: Recovery and Dose-Dependence

Inhaled irritants can cause respiratory depression by simulating trigeminal nerves in the nasal cavity. This decrease in inhalation rate results in a decrease in the rate of the irritant gases flowing to the stimulated nerves, creating a complex feedback response. Previously, a model was created to describe how the presence of formaldehyde affects respiration in the rat. This ordinary differential equation model incorporated a model of the physiology of the upper respiratory tract of the rat and a model of the neurological control of the respiration rate due to signaling from the stimulated nerves in the nasal cavity. However, an optimal fit to data was not fully established. In the current study, the fit of the previously established model is reevaluated while incorporating the recovery of the ventilation rate after the end of exposure. Additionally, the dose-dependence of the adaptation time allowed by the previous model is more fully quantified, and the updated model predicts formaldehyde data well. Not only are the results of the previous study improved, the model is also shown to predict ventilation decrease in response to other irritants, specifically acrolein, ammonia, and sulfur dioxide. The model is expected to translate to predictions of other irritants with minor parameter changes.     

Lethal and Sublethal Toxicity Comparison of BFRs to Three Marine Planktonic Copepods: Effects on Survival,Metabolism and Ingestion

The estuarine planktonic copepods have a wide geographical distribution and commendable tolerance to various kinds of contaminants. The primary aim of the present study was to contrast the impacts of model POPs (TBBPA and HBCD) on three common estuarine planktonic copepods (Oithona similis, Acartia pacifica and Pseudodiaptomus inopinus) and establish a protocol for the assessment of acute toxicity of marine organic pollutants. We first quantified the 96h-LC₅₀ (0.566, 0.04 and 0.257 mg/L of TBBPA to the three subjects above respectively and 0.314 mg/L of HBCD to P. inopinus; all reported concentrations are nominal values). In the sub-lethal toxicity tests, it was turned out that the effects of copepods exposed to TBBPA could product different influences on the energy ingestion and metabolism. Different type of pollutions, meanwhile, could also bring varying degree effect on the target copepods. In general, the indicators (the rate of oxygen consumption, ammonia excretion, food ingestion and filtration) in higher concentration groups showed marked significant difference compared with controls as well a dose-effect relationship. The study also extended the research on the joint toxicity of TBBPA and HBCD based on the survival rate of P.inopinus. Whether 1:1 concentration or 1:1 toxic level, the research showed synergy effect relative to single exposure conditions. The result indicated that current single ecological testing used for environmental protection activities may underestimate the risk for copepods. It was also demonstrated that short-term sub-lethal experiment could be a standard to evaluate the sensitivity of copepods to POPs.     

Brainstem Circuitry Regulating Phasic Activation of Trigeminal Motoneurons during REM Sleep

Background

Rapid eye movement sleep (REMS) is characterized by activation of the cortical and hippocampal electroencephalogram (EEG) and atonia of non-respiratory muscles with superimposed phasic activity or twitching, particularly of cranial muscles such as those of the eye, tongue, face and jaw. While phasic activity is a characteristic feature of REMS, the neural substrates driving this activity remain unresolved. Here we investigated the neural circuits underlying masseter (jaw) phasic activity during REMS. The trigeminal motor nucleus (Mo5), which controls masseter motor function, receives glutamatergic inputs mainly from the parvocellular reticular formation (PCRt), but also from the adjacent paramedian reticular area (PMnR). On the other hand, the Mo5 and PCRt do not receive direct input from the sublaterodorsal (SLD) nucleus, a brainstem region critical for REMS atonia of postural muscles. We hypothesized that the PCRt-PMnR, but not the SLD, regulates masseter phasic activity during REMS.

Methodology/Principal Findings

To test our hypothesis, we measured masseter electromyogram (EMG), neck muscle EMG, electrooculogram (EOG) and EEG in rats with cell-body specific lesions of the SLD, PMnR, and PCRt. Bilateral lesions of the PMnR and rostral PCRt (rPCRt), but not the caudal PCRt or SLD, reduced and eliminated REMS phasic activity of the masseter, respectively. Lesions of the PMnR and rPCRt did not, however, alter the neck EMG or EOG. To determine if rPCRt neurons use glutamate to control masseter phasic movements, we selectively blocked glutamate release by rPCRt neurons using a Cre-lox mouse system. Genetic disruption of glutamate neurotransmission by rPCRt neurons blocked masseter phasic activity during REMS.

Conclusions/Significance

These results indicate that (1) premotor glutamatergic neurons in the medullary rPCRt and PMnR are involved in generating phasic activity in the masseter muscles, but not phasic eye movements, during REMS; and (2) separate brainstem neural circuits control postural and cranial muscle phasic activity during REMS.     

Capsaicin alleviates the imbalance in xenobiotic metabolizing enzymes and tumor markers during experimental lung tumorigenesis

The maintenance of a differentiated chondrocyte phenotype is influenced by several factors of which signal transduction of extracellular stimuli through the cell membrane is of major interest. One important group of membrane-bound proteins which are involved in transmembrane signal transduction are ion channels. Human articular chondrocytes were obtained from osteoarthritic femoral condyles. Cells were released from the surrounding matrix and cultivated under standard conditions. We investigated gene expression of 12 members of the TRP ion channel family of freshly prepared (passage 0; P0) and in vitro propagated human articular chondrocytes (passage 2; P2) using conventional and real-time PCR (RT-PCR). In addition, the protein appearance of four TRP channels was demonstrated by immunofluorescence and western blotting. Chondrocyte differentiation was monitored by quantification of collagen type-II, type-I, and aggrecan gene expression. By conventional PCR, 8 channels could be detected, of which some displayed a heterogeneous PCR pattern. RT-PCR quantification revealed that TRPC1 was expressed on the same level in P0 and P2 chondrocytes while gene expression of TRPC3 and TRPC6 was elevated in passage 2 cells. TRPM5, TRPM7, and TRPV1 displayed an enhanced gene expression in freshly isolated chondrocytes. Immunofluorescence signal intensity of all four investigated TRP proteins was consistent with the corresponding gene expression data. In the present study, a correlation between the appearance of some members of the TRP ion channel family and the state of de-differentiation of osteoarthritic articular chondrocytes was shown. A possible direct involvement in the process of chondrocyte de-differentiation has to be investigated in further studies.     

Localization of Chemical Stimulation: Capsaicin on Hairy Skin

The ability to localize a chemical stimulus applied to the skin of the forearm was compared to the ability to localize a punctate tactile stimulus. The chemical stimulus was a single, 6-μ1 drop of a 1.0% solution of capsaicin in an ethanol vehicle; the tactile stimulus was a polyester monofilament that exerted 7.5 g of force. Subjects attempted to localize the stimuli at 30-sec intervals for a period of 13.5 min, and rated the perceived intensity and quality of the chemogenic sensations. To avoid generating potentially confounding tactile sensations, localization attempts were made by pointing to the area of sensation with a focused light beam. The results showed that overall, chemical localization was inferior to tactile localization: The absolute error of localization averaged 2.5 cm for capsaicin compared to 1.4 cm for the monofilament. The experiment also revealed that chemical localization (1) varied significantly across arms, (2) exhibited a relatively strong bias toward the elbow, and (3) appeared to be unaffected by the perceived intensity of the sensation. The dominant sensation quality reported was itch. The results are discussed in the context of cutaneous localization in general and localization in the nociceptive system in particular.     

植物辣椒素(碱)的生物合成和代谢

本文就辣椒素类物质的结构、性质,生物合成途径以及相关中间产物、竞争底物、关键酶和参与辣椒素降解代谢过程中的过氧化物酶研究进展作了介绍.     

葛根素提取及其抑菌实验研究

以湘西葛根为实验材料,选取水、甲醇和95％的乙醇作为提取溶剂,索氏提取法提取其葛根素。以提取率为指标,综合提取工艺中加入量、提取时间的影响,采用正交实验筛选出乙醇提取工艺,最佳参数为每次加入10倍量、回流提取时间3．5h。用滤纸片法研究葛根提取液对大肠杆菌等8种常见食品腐败菌的抑菌活性,结果表明,各种菌体的抑菌效果为：大肠杆菌〉金黄色葡萄球菌〉枯草芽孢杆菌〉假丝酵母青霉,对青霉无抑菌作用。各种菌的抑菌效果与浓度的关系为,葛根素浓度升高,抑菌效果增强。     

Protective Role of Capsaicin in Neurological Disorders: An Overview

Neurochemical Research - Different pathological conditions that begin with slow and progressive deformations, cause irreversible affliction by producing loss of neurons and synapses. Commonly it is...     

Relative Sensitivity of the Ocular Trigeminal, Nasal Trigeminal and Olfactory Systems to Airborne Chemicals

We measured thresholds for eye irritation and odor in homologousseries of alcohols (ethanol, 1-butanol, 1-hexanol and 1-octanol),ketones (2-propanone, 2-pentanone, 2-heptanone and 2-nonanone),and alkylbenzenes (toluene, ethyl benzene and propyl benzene).Eye irritation thresholds were well above odor thresholds forall series. Both sensory thresholds declined with carbon chainlength, a trend that has implicated lipophilicity in the potencyof these and related stimuli. Eye irritation thresholds wereremarkably close to nasal pungency thresholds obtained previouslyin persons lacking olfaction (i.e. anosmics). The agreementbetween the two thresholds implies that, despite differencesin the mucus layer at the two sites and in the epithelial tissueitself, there is remarkable similarity at the site of stimulation.As a practical matter, the eyes could serve as the sites toassess potency for induction of nasal pungency, an assessmentpreviously limited to testing anosmics. Presumably, for ourbrief stimulus presentations (1–3 s), the differencesbetween ocular and nasal mucosae have little relevance to chemicalsensitivity. Studies of the ability of homologous chemical seriesto evoke threshold eye irritation, nasal pungency and odor notonly have practical value, but also can help to define the physicochemicalproperties of the receptor and perireceptor biophases. ¹Present address: Department of Surgery (Otolaryngology), UCSDMedical Center, University of California, San Diego, USA     

Ingestion and inactivation of bacteriophages by Tetrahymena

Abiotic factors are thought to be primarily responsible for the loss of bacteriophages from the environment, but ingestion of phages by heterotrophs may also play a role in their elimination. Tetrahymena thermophila has been shown to ingest and inactivate bacteriophage T4 in co-incubation experiments. In this study, other Tetrahymena species were co-incubated with T4 with similar results. In addition, T. thermophila was shown to inactivate phages T5 and lambda in co-incubations. Several approaches, including direct visualization by electron microscopy, demonstrated that ingestion is required for T4 inactivation. Mucocysts were shown to have no role in the ingestion of T4. When (35)S-labeled T4 were fed to T. thermophila in a pulse-chase experiment, the degradation of two putative capsid proteins, gp23(*) and hoc, was observed. In addition, a polypeptide with the apparent molecular mass of 52 kDa was synthesized. This suggests that Tetrahymena can use phages as a minor nutrient source in the absence of bacteria.     

Ingestion of saliva during carbohydrate feeding by Lutzomyia longipalpis (Diptera; Psychodidae)

The aim of this study was to obtain experimental evidence that phlebotomine saliva is actually ingested during the carbohydrate ingestion phase (before and after blood digestion). The ingestion of carbohydrate was simulated as it occurs in the field by offering the insects balls of cotton soaked in sucrose, sucrose crystals or orange juice cells. The results obtained here showed that ingestion occurred under each condition investigated, as indicated by the presence of apyrase, an enzyme used as a marker to detect saliva in the insect gut and/or carbohydrate sources. Saliva ingestion by phlebotomine during the carbohydrate ingestion phase is important to explain how it could promote starch digestion and to trigger Leishmania promastigotes to follow a differentiation pathway as proposed previously by some authors.