Evaluation of a 13-hexyl-berberine hydrochloride topical gel formulation

13-hexyl-berberine hydrochloride (HB-13) is a derivative from berberine which finds widespread applications in the treatment of infectious pathogens including fungi, bacteria, parasites and viruses. As our continuing efforts for treatment of herpes simplex virus (HSV), we studied the topical delivery and safety of HB-13 in a gel formulation (0.5%) in a pig model. Our studies demonstrated the maximal HB-13 concentration was 2.51 µg/mL, which was more than the half maximal inhibitory concentration (IC₅₀) as we previously reported. In addition, there was no sign of irritation or histological aberrance for stripped skin continuously applied with 0.5% HB-13 gel for 21 days. In conclusion, 0.5% HB-13 gel can achieve effective anti-HSV concentration in the dermis and it is safe to use.     

Predictable and unpredictable rewards produce similar changes in dopamine tone.

Unpredicted rewards trigger more vigorous phasic responses in midbrain dopamine (DA) neurons than predicted rewards. However, recent evidence suggests that reward predictability may fail to influence DA signaling over longer scales: In rats passively receiving rewarding electrical brain stimulation, the concentration of DA in dialysate obtained from nucleus accumbens probes was similar regardless of whether reward onset was predictable (G. Hernandez et al., 2006). The present experiment followed up on these findings by requiring the rats to work for the rewarding stimulation, thus confirming whether they indeed learned the timing and predictability of reward delivery. Performance under fixed-interval and variable-interval schedules was compared, and DA levels in the nucleus accumbens were measured by means of in vivo microdialysis. The observed patterns of operant responding indicate that the rats working under the fixed-interval schedule learned to predict the time of reward availability, whereas the rats working under the variable-interval schedule did not. Nonetheless, indistinguishable changes in DA concentration were observed in the 2 groups. Thus, reward predictability had no discernable effect on a measure believed to track the slower components of DA signaling. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Experience-dependent effects of cocaine self-administration/conditioning on prefrontal and accumbens dopamine responses.

Experiments were performed to examine the effects of cocaine self-administration and conditioning experience on operant behavior, locomotor activity, and nucleus accumbens (NAcc) and prefrontal cortex (PFC) dopamine (DA) responses. Sensory cues were paired with alternating cocaine and nonreinforcement during 12 (limited training) or 40 (long-term training) daily operant sessions. After limited training, NAcc DA responses to cocaine were significantly enhanced in the presence of cocaine-associated cues compared with nonreward cues and significantly depressed after cocaine-paired cues accompanied a nonreinforced lever response. PFC DA levels were generally nonresponsive to cues after the same training duration. However, after long-term training, cocaine-associated cues increased the magnitude of cocaine-stimulated PFC DA levels significantly over levels observed with nonreinforcement cues. Conversely, conditioned cues no longer influenced NAcc DA levels after long-term training. In addition, cocaine-stimulated locomotor activity was enhanced by cocaine-paired cues after long-term, but not after limited, training. Findings demonstrate that cue-induced cocaine expectation exerts a significant impact on dopaminergic and behavioral systems, progressing from mesolimbic to mesocortical regions and from latent to patent behaviors as cocaine and associative experiences escalate. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

基于双酶固定化技术的微透析葡萄糖传感器

建立了一个双酶葡萄糖传感器微透析系统,并且在体外实验中考察了影响系统响应结果的关键因素,即固定化酶膜技术和微透析系统的灌注速率。优化的系统采用夹心法固定化葡萄糖氧化酶和过氧化氢酶于金叉指电极,并采用20μl/min的灌注速率。系统具有良好的线性、灵敏度和响应时间。     

Controlled microaspiration for high-pressure freezing: a new method for ultrastructural preservation of fragile and sparse tissues for TEM and electron tomography

High‐pressure freezing is the preferred method to prepare thick biological specimens for ultrastructural studies. However, the advantages obtained by this method often prove unattainable for samples that are difficult to handle during the freezing and substitution protocols. Delicate and sparse samples are difficult to manipulate and maintain intact throughout the sequence of freezing, infiltration, embedding and final orientation for sectioning and subsequent transmission electron microscopy. An established approach to surmount these difficulties is the use of cellulose microdialysis tubing to transport the sample. With an inner diameter of 200 μm, the tubing protects small and fragile samples within the thickness constraints of high‐pressure freezing, and the tube ends can be sealed to avoid loss of sample. Importantly, the transparency of the tubing allows optical study of the specimen at different steps in the process. Here, we describe the use of a micromanipulator and microinjection apparatus to handle and position delicate specimens within the tubing. We report two biologically significant examples that benefit from this approach, 3D cultures of mammary epithelial cells and cochlear outer hair cells. We illustrate the potential for correlative light and electron microscopy as well as electron tomography.     

Effects of Early Life Exposure to Sex Hormones on Neurochemical and Behavioral Responses to Psychostimulants in Adulthood: Implications in Drug Addiction

Early life exposure to sex hormones affects several brain areas involved in regulating locomotor and motivation behaviors. Our group has shown that neonatal exposure to testosterone propionate (TP) or estradiol valerate (EV) affected the brain dopamine (DA) system in adulthood. Here, we studied the long-lasting effects of neonatal exposure to sex hormones on behavioral and neurochemical responses to amphetamine (AMPH) and methylphenidate (MPD). Our results show that AMPH-induced locomotor activity was higher in female than male control rats. The conditioned place preference (CPP) to AMPH was only observed in EV male rats. In EV female rats, AMPH did not increase locomotor activity, but MPD-induced CPP was observed in control, EV and TP female rats. Using in vivo brain microdialysis, we observed that AMPH-induced extracellular DA levels were lower in nucleus accumbens (NAcc) of EV and TP female rats than control rats. In addition, MPD did not increase NAcc extracellular DA levels in EV rats. Using in vivo fast-scan cyclic voltammetry in striatum, MPD-induced DA reuptake was higher in EV than control rats. In summary, our results show that early life exposure to sex hormones modulates mesolimbic and nigrostriatal DA neurons producing opposite neurochemical effects induced by psychostimulant drugs in NAcc or striatum.     

Dopamine: Helping males copulate for at least 200 million years: Theoretical comment on Kleitz-Nelson et al. (2010).

Brain dopamine (DA) systems are implicated in a variety of behavioral responses and clinical syndromes, including sex, drug addiction, feeding, satiety, sleep, wakefulness, arousal, attention, reward, decision-making, depression, anxiety, psychosis, and movement disorders. The paper in this issue (see record 2010-24688-004) by Kleitz-Nelson, Dominguez, and Ball (2010) shows how DA release in the medial preoptic area of male quail are activated in an androgen-dependent manner during appetitive and consummatory phases of sexual behavior, similar to that reported previously in male rats. Those data suggest that the steroid-dependent role of hypothalamic DA in male sexual behavior has been conserved through evolutionary time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development and in-vivo evaluation of ondansetron gels for transdermal delivery

Nausea and vomiting are some of the major side effects caused by certain drug therapies, e.g. chemotherapy, radiotherapy and general anesthesia. Because of the nature of the symptoms, oral delivery is inappropriate, while intravenous administration may be unpractical. The aim of the present study was to develop a transdermal gel (2% Klucel®) for ondansetron, a first line 5-HT3-receptor-antagonist antiemetic. The effects of the penetration enhancer camphor and isopropyl-myristate (IPM) were first investigated in-vitro using modified Franz diffusion-cells and then tested in-vivo in a rabbit model by measuring skin and plasma concentrations. Since a disadvantage of transdermal delivery is a prolonged lag-time, the effect of skin treatment with a micro-needle roller was tested. The in-vitro permeation studies through excised porcine ear skin showed that the presence of 2.5% camphor or IPM increased steady state flux by 1.2- and 2.5-fold, respectively, compared to the control gel. Ondansetron was not detectable in either skin or plasma following in-vivo application of the base-gel, whereas the camphor gel and IPM gel delivered 20 and 81?µg/cm² of ondansetron, respectively. Microporation led to an increase in plasma C_max and AUC by 10.47?±?1.68-fold and 9.31?±?4.91-fold, respectively, for the camphor gel, and by 2.31?±?0.53-fold and 1.59?±?0.38-fold, respectively for the IPM gel. In conclusion, the 2.5% IPM gel demonstrated optimal in-vivo transdermal flux. Skin pretreatment with a micro-needle roller slightly improved the delivery of the IPM gel, whereas dramatically increased the transdermal delivery of the camphor gel.     

Effect of microporation on passive and iontophoretic delivery of diclofenac sodium

Abstract

Skin pretreatment with a microneedle roller (microporation (MP)) appears a simple and inexpensive technique to increase transdermal delivery of topically applied drug products. This study investigates the effect of MP on the passive and iontophoretic delivery of diclofenac (DCF) by quantifying dermis and plasma levels of DCF in a rabbit model. New Zealand albino female rabbits received either: (i) a topical application of 4?g of Voltaren® 1% gel with or without pretreatment with a microroller (0.5?mm needle length; density 23 microneedles per cm² area) or (ii) a DCF solution (40?mg/2.5?mL) via iontophoresis (IOMED transQ^E medium size patch), with or without microroller pretreatment. A 300?µA/cm² cathodic current was applied for 20?min for a total of 80 mA. DCF concentrations were monitored in dermis with microdialysis sampling every 20?min for 5?h. Plasma samples were collected over the same period. In the passive delivery studies, microroller pretreatment increased C_max by 1.5- and 2.0-fold in skin and plasma, respectively, and AUC by 1.5- and 2.4-fold in skin and plasma, respectively. In the iontophoresis delivery studies, microporation increased C_max by 2.0-fold both in skin and in plasma, and AUC by 1.1- and 1.8-fold in skin and plasma, respectively. In conclusion, microneedle pretreatment increased significantly the systemic exposure of DCF from either passive or iontophoretic delivery, whereas the effect in skin was less pronounced.