NMDA antagonist effects on striatal dopamine release: microdialysis studies in awake monkeys.

Brain imaging studies have suggested that the NMDA antagonist ketamine is as potent a releaser of striatal dopamine as amphetamine. This conclusion contradicts microdialysis findings in the rodent that NMDA antagonists, in contrast to amphetamine, have little or no effect on striatal dopamine release. The present study addressed two mechanisms that could account for this discrepancy: 1) whether there is a species difference, i.e., rodents vs. primates, in the responsivity of striatal dopamine to NMDA antagonists, and 2) whether rapid uptake of dopamine prevents reliable measures of synaptic dopamine release by microdialysis in response to NMDA antagonists. MRI-directed in vivo microdialysis was used to compare the effects of psychotomimetic NMDA antagonists phencyclidine (PCP), ketamine, and amphetamine on extracellular striatal dopamine levels in awake rhesus monkeys. The effect of PCP was also investigated in the presence of intrastriatally applied nomifensine, a dopamine uptake blocker. Amphetamine (0.1 or 0.4 mg/kg) produced robust and dose-dependent increases in dopamine release ranging 2-10-fold above baseline. PCP at 0.1 mg/kg had no effect and at 0.3 mg/kg produced a small 50% increase over baseline. Ketamine, at the relatively high dose of 5 mg/kg, produced only a 30% increase in dopamine release. Intrastriatal application of nomifensine did not influence the effect of PCP, suggesting that rapid uptake of dopamine is not preventing the detection of a PCP-induced increase in dopamine release. These findings suggest that in the primate, ketamine and PCP are not effective dopamine releasers, as has been suggested by previous imaging studies.     

Margins of excision for cutaneous melanoma of the eyelid skin: the Collaborative Eyelid Skin Melanoma Group Report

PURPOSE: To evaluate the practice patterns among surgeons who treat melanomas of the eyelid skin with respect to margins of excision and to look for possible correlation between margins of excision and the incidence of local and regional recurrence and distant metastasis. METHODS: A retrospective survey of the members of the American Society of Ophthalmic Plastic and Reconstructive Surgery and the European Society of Ophthalmic Plastic and Reconstructive Surgery yielded 44 cases. The patients' age, sex, date of diagnosis, histologic classification of melanoma, Breslow thickness, Clark level, location of melanoma, size of margins of excision, and findings of local or regional recurrence or distant metastasis were recorded in each case. Patients were stratified on the basis of margins of excision: 5 mm but <10 mm; and >/=10 mm. Patients were also stratified by Breslow thickness. A Cox regression model was used to evaluate the predictive value of each factor for recurrence. Main outcome measures were the incidences of local and regional recurrence and distant metastasis as a function of margins of excision and Breslow thickness. RESULTS: The majority of patients for whom reliable information was available had excision margins of /=10 mm, but this difference was not statistically significant because very few patients had melanomas at least 2 mm thick. Breslow thickness was the only statistically significant predictor of local, regional, and distant metastasis. Margins of excision did not have a statistically significant effect on local, regional, or distant recurrence. CONCLUSIONS: Breslow thickness is an important prognostic indicator for eyelid skin melanomas. A 5-mm margin of excision may be adequate for thin melanomas of the periocular skin, but because of the small number of patients in this series who had >5-mm margins, a definitive comparison of outcome with larger margins of excision cannot be made. For melanomas >/=2 mm, wider margins of excision may be prudent, and careful surveillance for local and regional recurrence is indicated.     

Blockage of the lacrimal drainage apparatus as a side effect of docetaxel therapy

BACKGROUND: The current study was conducted to report the severity and management of canalicular and nasolacrimal duct stenosis as a side effect of docetaxel therapy and to report the outcomes of surgical intervention for this condition. METHODS: The records of 148 patients with epiphora associated with docetaxel therapy who were evaluated at the Ophthalmology Service at The University of Texas M. D. Anderson Cancer Center were reviewed. The frequency of docetaxel administration, the dose intensity, the cumulative dose of docetaxel, and any concomitant chemotherapeutic agents were recorded. Each patient underwent an ophthalmologic examination and in-office probing and irrigation. The patients either were treated with topical steroids or offered a surgical procedure for canalicular stenosis- (silicone intubation, dacryocystorhinostomy [DCR] with the placement of silicone tubes, or DCR with the placement of Pyrex glass tubes), depending on the severity of the canalicular stenosis. RESULTS: Docetaxel was given weekly in 71 patients, every 2 weeks in 5 patients, and every 3 weeks in 72 patients. Thirty patients (59 eyes) who received weekly docetaxel underwent surgery to correct epiphora. Twenty-three patients (39 eyes) were treated with temporary silicone tube placement, 9 patients (13 eyes) were treated with DCR with temporary silicone tube placement, and 4 patients (7 eyes) were treated with DCR with permanent Pyrex glass tube placement. Twenty-nine of the 30 patients who underwent surgery reported improvement or total resolution of epiphora after the procedure. Ten additional patients (20 eyes) who received weekly docetaxel had complete closure of their canaliculi but elected not to undergo surgery. Of special note were two patients who received weekly docetaxel in the neoadjuvant setting and developed complete closure of the canaliculi. Of the patients who received docetaxel every 2 or 3 weeks, only 3 required a surgical intervention to correct epiphora; none required Pyrex glass tube placement. CONCLUSIONS: Canalicular and nasolacrimal duct obstruction is a common side effect of weekly docetaxel therapy and can occur even when this drug is used in the neoadjuvant setting. The results of the current study indicate that early temporary silicone intubation in symptomatic patients receiving weekly docetaxel can prevent further closure of the lacrimal drainage apparatus and obviate more involved surgical interventions and permanent Pyrex glass tube placement. Cancer 2003;98:504-7.     

Distinct contributions of glutamate and dopamine receptors to temporal aspects of rodent working memory using a clinically relevant task

RATIONALE: Understanding the mechanistic basis of working memory, the capacity to hold representation "on line," is important for delineating the processes involved in higher cognitive functions and the pathophysiology of thought disorders. OBJECTIVES: We compared the contribution of glutamate and dopamine receptor subtypes to temporal aspects of working memory using a modified rodent spatial working memory task that incorporates important elements of clinical working memory tasks. METHODS: A discrete paired-trial variable-delay T-maze task was used. Initial characterization studies indicated that performance on this task is stable at seconds-long retention intervals, is sensitive to retention interval and proactive interference, and is dependent on the integrity of the medial prefrontal cortex. RESULTS: Consistent with clinical findings, low dose amphetamine (0.25 mg/kg) produced a delay-dependent improvement in performance, while higher doses impaired performance at all retention intervals. D1 receptor blockade produced the predicted dose- and delay-dependent impairment. D2 receptor blockade had no effect. Activation of metabotropic glutamate 2/3 (mGluR2/3) receptors, which in the prefrontal cortex inhibits the slow asynchronous phase of glutamate release, also produced a delay-dependent impairment. Low doses of an AMPA/kainate antagonist had effects similar to the mGluR2/3 agonist. In contrast, NMDA receptor antagonist-induced impairment was memory load-insensitive, resulting in chance-level performance at all retention intervals. CONCLUSIONS: These findings suggest that activation of NMDA receptors is necessary for the formation of mnemonic encoding while modulatory components involving slow asynchronous release of glutamate and phasic release of dopamine contribute to the active maintenance of information during the delay period.     

Classification of stimuli–responsive polymers as anticancer drug delivery systems

Abstract

Although several anticancer drugs have been introduced as chemotherapeutic agents, the effective treatment of cancer remains a challenge. Major limitations in the application of anticancer drugs include their nonspecificity, wide biodistribution, short half-life, low concentration in tumor tissue and systemic toxicity. Drug delivery to the tumor site has become feasible in recent years, and recent advances in the development of new drug delivery systems for controlled drug release in tumor tissues with reduced side effects show great promise. In this field, the use of biodegradable polymers as drug carriers has attracted the most attention. However, drug release is still difficult to control even when a polymeric drug carrier is used. The design of pharmaceutical polymers that respond to external stimuli (known as stimuli–responsive polymers) such as temperature, pH, electric or magnetic field, enzymes, ultrasound waves, etc. appears to be a successful approach. In these systems, drug release is triggered by different stimuli. The purpose of this review is to summarize different types of polymeric drug carriers and stimuli, in addition to the combination use of stimuli in order to achieve a better controlled drug release, and it discusses their potential strengths and applications. A survey of the recent literature on various stimuli–responsive drug delivery systems is also provided and perspectives on possible future developments in controlled drug release at tumor site have been discussed.     

Natural Oils Enhance IL-10 and IFN-γ Production by Human PBMCs Cultured with Malassezia furfur

Background: Malassezia furfur is a lipophilic yeast that causes skin disease. Objective: To evaluate the level of IL-10, IFN-γ and IL-12P70 in co-incubation of peripheral blood mononuclear cells (PBMCs) with M. furfur grown in the presence of some different types of natural oils. Methods: PBMCs were obtained from blood samples of normal volunteers. M. furfur was cultured in different culture media containing almond oil, fish oil, walnut oil, full-fat milk, and a fat-free medium; and the yeasts grown were harvested and used for co-incubation with PBMCs in vitro. The IFN-γ, IL-10, and IL-12P70 levels were measured at different time intervals using ELISA methods. Results: Generally, IFN-γ and IL-10 levels in the co-incubation of yeasts with walnut oil group (WOG) and fish oil group (FOG) were higher than those in the almond oil group (AOG) and full-fat milk group (FFMG). Although the IL-12P70 was higher in groups such as AOG, FOG, and WOG; the increase was not statistically significant. Conclusion: The results demonstrated that the type of fat used by M. furfur in the culture media can influence the immune response and increasesIFN-γ and IL-10 levels in an early time point of the culture system.     

Low dose ribavirin for treatment of hepatitis C virus infected thalassemia major patients; new indications for combination therapy

Background

Treatment guidelines contraindicate ribavirin for treatment of hepatitis C virus (HCV) infection in thalassemia major patients. Nevertheless, the current evidence suggests that ribavirin might be tolerated by these patients.

Objectives

Despite this evidence, low dose ribavirin combination therapy has not been compared with peginterferon monotherapy in these patients so far.

Patients and Methods

Two hundred eighty thalassemia patients with detectable HCV-RNA PCR (≥ 50 IU/mL) and liver histology consistent with chronic HCV infection were self-assigned to receive peginterferon alfa-2a (n = 81) monotherapy or its combination therapy with ribavirin, 600-800 mg QD, according to hemoglobin levels (n = 199). Treatment experienced patients were eligible for this study.

Results

Sustained virological response (SVR) was significantly higher in patients who received ribavirin (51 % vs. 38 % P = 0.02). In multivariate regression, OR of ribavirin for prediction of SVR was 2.2 (95 % CI 1.24-3.91). The SVR was significantly higher in the ribavirin group in subgroups of patients with more than 24 years of age, elevated ALT, ferritin < 2006 ng/mL, previous treatment failure, genotype 1, positive history of splenectomy, fibrosis score of 0-4 HAI and viral load < 600,000 IU/mL. Treatment discontinuations due to the safety concerns were comparable between the treatment groups (6.5 and 8 %). Furthermore, transfusion intervals were almost halved in patients who received low dose ribavirin.

Conclusions

According to the present study, adult thalassemia patients with HCV infection can be treated successfully with low dose ribavirin. Hence, we strongly advise combination therapy in thalassemia patients with aforementioned clinical characteristics. Moreover, ribavirin does not seem to be beneficial in thalassemia patients below 18 years of age.