Preparation and evaluation of temperature sensitive liposomes containing adriamycin and cytarabine

Temperature sensitive liposomes (TSL) containing adriamycin (ADM) and cytarabine (Ara-C) were prepared. ADM and Ara-C were selected as model compounds of amphiphilic and hydrophilic drug, respectively. Encapsulation efficiency of ADM entrapped into TSL was about twice greater than that of Ara-C. It might be due to different polarity of the drugs. Lipid compositions of TSL had no effect on the encapsulation efficiency of drugs. Thermal behavior of TSL using a differential scanning calorimetry (DSC) was also investigated. Phase transition temperature (T_c) of TSL was dependent on the lipid compositions of TSL.ADM broadened thermogram of TSL but Ara-C did not. However, T_c of TSL was not changed by any drug. Release rate of drugs was highly dependent on temperature. The release profile of ADM was similar to that of Ara-C. The maximum release rate of drugs from TSL was occurred at the near T_c and observed at 39–41°C for DPPC (Dipalmitoylphosphatidylcholine) only, 52–54°C for DSPC (Distearoylphosphatidylcholine) only, 41–43°C for DPPC and DSPC (3∶1), and 43–45°C for DPPC and DSPC (1∶1), respectively. Effect of human serum albumin (HSA) on the release rate of ADM was investigated. HSA had no significant effect on the release of ADM below T_c. However, ADM release from TSL was increased at the near and above T_c. The HSA-induced leakage of drug may result from the interaction of liposomal constituents with HSA structure at the near T_c. From the fact that the release profiles of ADM from freshly prepared TSL and stored TSL for 1 week at 4°C was not changed, the TSL was considered to be stable for at least 1 week at 4°C. Based on these findings, TSL may be useful to deliver drugs to preheated target sites due to its thermal behaviors.     

P-glycoprotein (P-gp) function in T cells: implications for organ transplantation

P-glycoprotein (P-gp), a member of the adenosine triphosphate (ATP)-binding cassette (ABC) family of transporter molecules, is responsible for maintaining low intracellular concentrations of a variety of extracellular compounds and xenobiotics, and for transport of various intracellular molecules. Many drugs are P-gp substrates and intracellular concentrations of these agents may be critical for drug action. Experience in oncology indicates that repeated exposure to P-gp substrate cytotoxic drugs leads to the selection of drug-resistant tumor cells that overexpress P-gp. Since immunosuppressive agents such as cyclosporine, tacrolimus, sirolimus and corticosteroids are substrates for P-gp and since T-cells also express P-gp, it is conceivable that an analogous mechanism exits for therapy-resistant graft rejection. As will be discussed in this article, P-gp may interfere with the response to immunosuppressive therapy through several distinct mechanisms, and as such may represent an attractive therapeutic target.     

Effects of Carbamazepine on Murine Humoral and Cellular Immune Responses

Summary: Oral administration of carbamazepine (CBZ)(15, 10, or 5 mg/kg) to mice significantly decreased both humoral and cellular immune responses evaluated by enumeration of direct and indirect plaque-forming spleen cells (PFC) and delayed–type hypersensitivity reaction (DTH) against sheep red blood cells (SRBC) as compared with those observed in normal control animals. Moreover, spleen T cells obtained from CBZ–treated donor mice were capable of decreasing both PFC and DTH responses of normal spleen cells transferred into lethally irradiated recipient animals. The immunodepressor effect of CBZ was observed even though administration of CBZ induced augmentation of spleen cellularity.     

Pharmacological effects of epibatidine optical enantiomers

The pharmacology of synthetic - and -epibatidine, an alkaloid originally characterized from frog skin, were studied in different behavioral tests in mice and rats. The two enantiomers have potent antinociceptive activity in mice using the tail-flick test, with an ED₅₀ of 6.1 and 6.6 μg/kg for - and -epibatidine respectively. Epibatidine enantiomers were 200 × more potent than -nicotine as an antinociceptive agent in mice after s.c. administration. Their analgesic effect was blocked by mecamylamine but not naloxone, an opiate antagonist. Both - and -epibatidine have high affinity (K_i 54.7 and 55.0 pM, respectively) for [³H]nicotine binding site in rat brain. In addition, they reduced mice locomotor activity and body temperature in a dose-dependent manner. In rats trained with nicotine (0.4 mg/kg), epibatidine enantiomers engendered nicotine-like responding in a dose-related manner with an ED₅₀ of 1.00 and 0.93 μg/kg for and , respectively. The discriminative effect of - and -epibatidine in rats was blocked by mecamylamine but not by hexamethonium. As in binding results, there was no significant enantioselectivity for these effects in our study.     

战伤绿脓杆菌感染源及防治研究

本文对云南老山前、后方医院环境及战伤感染标本中绿脓杆菌(简称PA)进行调查,对所分离的333株PA进行血清学分型及药物敏感性测定。结果可看出除炸伤时创口易被泥土中PA污染外,前、后方医院环境也是感染源之一。提示各级医疗单位在战伤救治中对PA的监控十分重要。本文结果直接有益于前、后方医院对战创伤PA的防治。     

Anticonvulsant Activities of 4–Bromobenzaldehyde Semicarbazone

Summary: Some of the properties of 4–bromobenzalde-hyde semicarbazone (compound IV), a prototype molecule of a new class of anticonvulsants, aryl semicarbazones, are described. Compound IV demonstrated activity in the maximal electroshock (MES) and subcutaneous pentylenetetrazol (scPTZ) tests in mice, with low neurotoxicity. When given orally to rats, it displayed high potency in the MES test and very low neurotoxicity, resulting in a high protective index (PI). Compound IV displayed no proconvulsant properties, and development of rapid tolerance was not noted. When administered intraperitoneally (i.p.) at doses of 100, 300, or 600 mg/kg to rats, compound IV had no effect on levels of γ-aminobu-tyric acid (GABA) or on GABA-T activity in whole brain. When tested in vitro, compound IV had no effect on rat brain GABA-T at a drug concentration of 100 μM. Although the activities of certain drug-metabolizing enzymes were increased after oral administration of compound IV to rats, these effects were less prominent than those of phenytoin (PHT) and carbamazepine (CBZ). The principal mode of action of compound IV does not appear to be an interaction with the GABA_A receptor complex, and other mechanisms, involving excitatory amino acid neurotransmission, will have to be considered in future investigations of the anticonvulsant activity of this compound.     

Femoral Pseudoaneurysm in Drug Addicts—Excision without Revascularization is a Viable Option

PURPOSE: To present a series of patients presenting with femoral pseudoaneurysm. RESULTS: Seventeen patients who presented with a femoral pseudoaneurysm during a 1 year period were included in this study. Parenteral drug abuse was the most common aetiological factor. The femoral artery was most commonly involved at its bifurcation. Sixteen patients (94%) had excision of the pseudoaneurysm with ligation of vessel and debridement without any revascularization and one patient (6%) had reverse saphenous grafting after excision and ligation of vessels. Four amputations (23%) were performed. Three (17%) were major limb amputations, which included one above knee and two below knee amputations. Four patients (23%) developed intermittent claudication. CONCLUSION: Excision of the pseudoaneurysm with ligation of vessels and wide debridement without immediate revascularization in infected pseudoaneurysms is a safe and effective treatment.     

When poor solubility becomes an issue: From early stage to proof of concept

Drug absorption, sufficient and reproducible bioavailability and/or pharmacokinetic profile in humans are recognized today as one of the major challenges in oral delivery of new drug substances. The issue arose especially when drug discovery and medicinal chemistry moved from wet chemistry to combinatorial chemistry and high throughput screening in the mid-1990s. Taking into account the drug product development times of 8–12 years, the apparent R&D productivity gap as determined by the number of products in late stage clinical development today, is the result of the drug discovery and formulation development in the late 1990s, which were the early and enthusiastic times of the combinatorial chemistry and high throughput screening. In parallel to implementation of these new technologies, tremendous knowledge has been accumulated on biological factors like transporters, metabolizing enzymes and efflux systems as well as on the physicochemical characteristics of the drug substances like crystal structures and salt formation impacting oral bioavailability. Research tools and technologies have been, are and will be developed to assess the impact of these factors on drug absorption for the new chemical entities.

The conference focused specifically on the impact of compounds with poor solubility on analytical evaluation, prediction of oral absorption, substance selection, material and formulation strategies and development. The existing tools and technologies, their potential utilization throughout the drug development process and the directions for further research to overcome existing gaps and influence these drug characteristics were discussed in detail.     

东乡族及回族吸毒人群性激素水平的变化

本文测定了东乡族、回族吸毒者血清睾酮及促黄体生成素含量，发现血清睾酮含量吸毒组（ｎ＝４０，Ｘ＝３４０．１４±１０１．４９ｎｇ／ｄＬ）显著低于非吸毒组（ｎ＝４２，Ｘ＝４４４．５０±９８．８３ｎｇ／ｄＬ），Ｐ＜０．０１。未观察到ＬＨ含量的改变。戒毒期２０日以内组血清睾酮含量（ｎ＝１６，Ｘ＝２９７．９３±７８．２２ｎｇ／ｄＬ），低于戒毒期２０～６０日组（ｎ＝１７，Ｘ＝３８６．２９±８９．４５ｎｇ／ｄＬ），Ｐ＜０．０１。询问１０３名吸毒者，２月后性欲下降２５人（２４．２７％），增强２人（１．９４％），无变化１３人（１２．６２％），不愿回答者６３人（６１．１７％）。吸毒影响性功能，损害性健康。