Prophylactic Role of Liposomized Chloroquine Against Murine Cryptococcosis Less Susceptible to Fluconazole

No HeadingPurpose. The prophylactic role of liposomized chloroquine (lip-CQ) has been assessed against less susceptible Cryptococcus neoformans infection in murine model.Methods. In the current study, we investigated the antifungal activity of lip-CQ against C. neoformans in macrophages cell line (J 774) and murine model. Mice were pretreated with free as well as liposomized formulations of CQ at various doses. The anticryptococcal activity of fluconazole was compared in mice with or without CQ pretreatment. The efficacy of CQ prophylaxis was assessed by survival as well as colony forming units (cfu) in brain and lungs of treated mice.Results. Fluconazole alone was not found significantly effective against C. neoformans in both in vitro and in vivo studies. However, the antifungal activity of fluconazole increases in chloroquine-pretreated mice. Lip-CQ was found to be more effective in comparison to the same dose of free chloroquine in reducing fungal burden from macrophages in vitro and lungs and brain of C. neoformans infected mice.Conclusions. The enhanced prophylactic activity of lip-CQ seems due to rapid uptake of drug-containing liposomes by macrophages. The liposome-mediated accumulation of CQ in macrophages makes the environment unfavorable (alkaline) for the intracellular multiplication of C. neoformans. Moreover, the increased incidence of multidrug resistance and diversity of pathogenic microorganisms inhibited or killed by CQ makes it the drug of choice for prophylactic therapy.     

A nano-liposome vaccine carrying E75, a HER-2/neu-derived peptide,exhibits significant antitumour activity in mice

E75 (HER-2/neu-369–377), is an immunogenic peptide which is highly expressed in breast cancer patients. The purpose of this study was to develop an effective vaccine delivery/adjuvant system by attachment of this peptide to the surface of liposomes consisting of phospholipids including distearoylphosphocholine (DSPC) and distearoyl phosphoglycerol (DSPG) with high transition temperature (Tm) and dioleoylphosphatidylethanolamine (DOPE) (a pH-sensitive lipid for cytosolic antigen delivery) to improve antitumour immune activity against the E75 peptide. For this purpose, the E75 peptide was incorporated into liposomes consisting of DSPC/DSPG/cholesterol (Chol)/DOPE (15/2/3/5 molar ratio) through conjugation with distearoylphosphoethanolamine-N-[maleimide(polyethylene glycol)-2000] (maleimide-PEG₂₀₀₀-DSPE). Immunization of BALB/c mice was performed three times with different forms of liposomal formulations at 2-week intervals and antitumour immunity responses were evaluated. Results of ELISpot and flow cytometry analysis showed that mice vaccinated with DSPC/DSPG/Chol/DOPE/E75 have significantly enhanced the antigen-specific IFN-γ response of CD8⁺ T cells and generated cytotoxic T lymphocytes (CTL) antitumour responses. CTL responses induced by this formulation resulted in inhibition of tumour progression and longer survival time in the mice TUBO tumour model. The results revealed that the liposomes consist of DSPC/DSPG/Chol/DOPE could be suitable candidates for vaccine delivery of E75 peptide for the prevention and therapy of HER2-positive breast cancer and merit further investigation.     

Use of liposomized tetracycline in elimination of Wolbachia endobacterium of human lymphatic filariid Brugia malayi in a rodent model

Wolbachia bacteria, being filarial parasite symbiont have been implicated in a variety of roles, including development, fecundity and the pathogenesis of the filarial infections. Among various strategies used in the treatment of experimental filariasis, the elimination of symbiont Wolbachia seem to offer an efficient means of curing the disease. The antiwolbachial property of tetracycline has been well worked out; however, treatment needs to be continued for a prolonged period of time to achieve complete elimination of Wolbachia from the filarial parasites and their subsequent killing. This results in acute toxicity, thus limiting its practical utility for clinical implementation. In order to increase efficacy of the antibiotic with minimal toxic manifestations, we developed liposomized formulation of the tetracycline. The liposomized tetracycline was found to be significantly more effective when compared to the free form of the drug. In contrast to the 90/120 days oral administration of the drug, the treatment schedule using the liposomized form of the drug was reduced to 12 alternate days with better efficacy of the treatment.     

Liposome-mediated DNA Immunisation via the Subcutaneous Route

Compared to naked DNA immunisation, entrapment of plasmid-based DNA vaccines into liposomes by the dehydration–rehydration method has shown to enhance both humoural and cell-mediated immune responses to encoded antigens administered by a variety of routes. In this paper, we have investigated the application of liposome-entrapped DNA and their cationic lipid composition on such potency after subcutaneous immunisation. Plasmid pI.18Sfi/NP containing the nucleoprotein (NP) gene of A/Sichuan/2/87 (H3N2) influenza virus in the pI.18 expression vector was incorporated by the dehydration–rehydration method into liposomes composed of 16 μmol egg phosphatidylcholine (PC), 8 μmoles dioleoyl phosphatidylethanolamine (DOPE) or cholesterol (Chol) and either the cationic lipid 1,2-diodeoyl-3-(trimethylammonium) propane (DOTAP) or cholesteryl 3?-N-(dimethyl amino ethyl) carbamate (DC-Chol). This method, entailing mixing of small unilamellar vesicles (SUV) with DNA, followed by dehydration and rehydration, yielded incorporation values of 90–94% of the DNA used. Mixing or rehydration of preformed cationic liposomes with 100 μg plasmid DNA also led to similarly high complexation values (92–94%). In an attempt to establish differences in the nature of DNA association with these various liposome preparations their physico-chemical characteristics were investigated. Studies on vesicle size, zeta potential and gel electrophoresis in the presence of the anion sodium dodecyl sulphate (SDS) indicate that, under the conditions employed, formulation of liposomal DNA by the dehydration–rehydration generated submicron size liposomes incorporating most of the DNA in a manner that prevents DNA displacement through anion competition. The bilayer composition of these dehydration–rehydration vesicles (DRV(DNA)) can also further influence these physico-chemical characteristics with the presence of DOPE within the liposome bilayer resulting in a reduced vesicle zeta potential. Subcutaneous liposome-mediated DNA immunisation employing two DRV(DNA) formulations as well as naked DNA revealed that humoural responses (immunoglobulin total IgG, and subclasses IgG₁ and 1gG_2a) engendered by the plasmid encoded NP were substantially higher after dosing twice, 28 days apart with 10 μg liposome-entrapped DNA compared to naked DNA. At all time points measured, mice immunised with naked DNA showed no greater immune response compared to the control, non-immunised group. In contrast, as early as day 49, responses were significantly higher in mice injected with DNA entrapped in DRV liposomes containing DOTAP compared to the control group and mice immunised with naked DNA. By day 56, all total IgG responses from mice immunised with both DRV formulations were significantly higher. Comparison between the DRV formulations revealed no significant difference in immune responses elicited except at day 114, where the humoural responses of the group injected with liposomal formulation containing DC-Chol dropped to significantly lower levels that those measured in mice which received the DOTAP formulation. Similar results were found when the IgG₁ and IgG_2a subclass responses were determined. These results suggest that, not only can DNA be effectively entrapped within liposomes using the DRV method but that such DRV liposomes containing DNA may be a useful system for subcutaneous delivery of DNA vaccines.     

Enhancement of solubility and dissolution of Coenzyme Q10 using solid dispersion formulation

This study aimed to develop a stable solid dispersion of Coenzyme Q₁₀ (CoQ₁₀) with high aqueous solubility and dissolution rate. Among various carriers screened, poloxamer 407 was most effective to form a superior solid dispersion of CoQ₁₀ having significantly enhanced solubility. Particularly, solid dispersion of CoQ₁₀ with poloxamer 407 in the weight ratio of 1:5 prepared by melting method enhanced the solubility of CoQ₁₀ to the greatest extent. However, it exhibited poor stability and hence Aerosil^® 200 (colloidal silicon dioxide) was incorporated into the solid dispersion as an adsorbent to inhibit the recrystallization process. The solid dispersion of CoQ₁₀, poloxamer 407 and Aerosil^® 200 in the weight ratio of 1:5:6 exhibited improved stability with no significant change in solubility during the 1-month stability test. Moreover, the solid dispersion formulation containing Aerosil^® 200 significantly enhanced the extent of drug release (approx. 75% release) as well as the dissolution rate of CoQ₁₀. In conclusion, the present study has developed the stable solid dispersion formulation of CoQ₁₀ with poloxamer 407 and Aerosil^® 200 for the enhanced solubility and dissolution of CoQ₁₀, which could also offer some additional advantages including ease of preparation, good flowability and cost-effectiveness.     

Prostaglandin E<Subscript>2</Subscript>-mediated dysregulation of proinflammatory cytokine production in pristane-induced lupus mice

Systemic lupus erythematosus (SLE) is characterized by inflammatory and dysregulatory immune responses including overactive B cells, overproduction of proinflammatory cytokines, and T cell hyperactivity. PGE₂ modulates a variety of immune processes at sites of inflammation, including production of inflammatory cytokines. However, the role of PGE₂ in dysregulatory inflammatory and immune responses in lupus remains unclear. We investigated whether PGE₂ mediates production of inflammatory cytokines in pristane-induced lupus BALB/c mice. Our results showed that levels of serum and BAL PGE₂ and LPS-stimulated production of PGE₂ by peritoneal macrophages were remarkably increased in pristane-induced lupus mice compared to healthy controls. Exogenous PGE₂ enhanced production of IL-6, IL-10, and NO but decreased TNF-α by macrophages and augmented IFN-γ, IL-6, and IL-10 by splenocytes from pristane-induced lupus mice compared to healthy controls. Exogenous PGE₂ also enhanced production of IFN-γ, IL-6, and IL-10 by thymocytes from pristane-induced lupus mice. Indomethacin (Indo), a PGE₂ synthesis inhibitor, greatly inhibited LPS-induced production of IL-6 and IL-10 by macrophages from pristane-induced lupus mice, while enhanced TNF-α. Indo remarkably inhibited Con A-increased production of IFN-γ, IL-6, and IL-10 by splenocytes and thymocytes from pristane-induced lupus mice. Therefore, our findings suggest that endogenous PGE₂ may mediate dysregulation of production of proinflammatory cytokines, such as IL-6, IL-10, and IFN-γ, and NO in pristane-induced lupus mice.     

Role of MT1 melatonin receptors in methamphetamine-induced locomotor sensitization in C57BL/6 mice

Rationale

Melatonin modifies physiological and behavioral responses to psychostimulants, with the MT₁ and MT₂ melatonin receptors specifically implicated in facilitating methamphetamine (METH)-induced sensitization in melatonin-proficient mice.

Objective

The objective of the study is to assess differences in locomotor sensitization after a single dose of methamphetamine in low-melatonin-expressing C57BL/6 wild-type and MT₁ receptor knockout (MT₁KO) mice, comparing with melatonin-expressing C3H/HeN mice.

Methods

Mice received a vehicle or methamphetamine (1.2 mg/kg, i.p.) pretreatment (day 1) during the light (ZT5-9) or dark (ZT 19–21) periods in novel test arenas. Locomotor sensitization was assessed by methamphetamine challenge after an eight-day abstinence (day 9). TH protein expression was evaluated by immunofluorescence and Western blot analysis.

Results

Methamphetamine pretreatment induced statistically significant locomotor sensitization upon challenge after eight-day abstinence in C3H and C57 wild-type mice during the light period. The magnitude of sensitization in C57 mice was diminished in the dark period and completely abrogated in MT₁KO mice. No differences were observed in tyrosine hydroxylase immunoreactivity in the mesolimbic dopamine system. Additional exposures to the test arenas after methamphetamine pretreatment (nights 2–6) enhanced sensitization.

Conclusions

Deletion of the MT₁ melatonin receptor abolishes sensitization induced by a single METH pretreatment. The magnitude of sensitization is also altered by time of day and contextual cues. We conclude that the MT₁ melatonin receptor is emerging as a novel target of therapeutic intervention for drug abuse disorders.     

Kanechlor 500‐mediated changes in serum and hepatic thyroxine levels primarily occur in a transthyretin‐unrelated manner

The effects of Kanechlor‐500 (KC500) on the levels of serum total thyroxine (T₄) and hepatic T₄ in wild‐type C57BL/6 (WT) and its transthyretin (TTR)‐deficient (TTR‐null) mice were comparatively examined. Four days after a single intraperitoneal injection with KC500 (100 mg/kg body weight), serum total T₄ levels were significantly decreased in both WT and TTR‐null mice. The KC500 pretreatment also promoted serum [¹²⁵I]T₄ clearance in both strains of mice administrated with [¹²⁵I]T₄, and the promotion of serum [¹²⁵I]T₄ clearance in WT mice occurred without inhibition of the [¹²⁵I]T₄‐TTR complex formation. Furthermore, the KC500 pretreatment led to significant increases in liver weight, steady‐state distribution volume of [¹²⁵I]T₄, hepatic accumulation level of [¹²⁵I]T₄, and concentration ratio of the liver to serum in both strains of mice. The present findings indicate that the KC500‐mediated decrease in serum T₄ level occurs in a TTR‐unrelated manner and further suggest that KC500‐promoted T₄ accumulation in the liver occurs through the development of liver hypertrophy and the promotion of T₄ transportation from serum to liver.     

The polyhydroxylated fullerene derivative C60(OH)24 protects mice from ionizing-radiation-induced immune and mitochondrial dysfunction

Although the protective effect of the polyhydroxylated fullerene derivative C₆₀(OH)_n against ionizing radiation is an area of much interest, the mechanisms relating to how polyhydroxylated fullerene derivatives improve mitochondrial dysfunction remain unknown. In order to find new and effective radioprotective agents, we synthesized a new polyhydroxylated fullerene molecule with 24 hydroxyl groups of known positions on C₆₀ and studied its protective effects in mice subjected to irradiation. Mice were pretreated with C₆₀(OH)₂₄ for 2 weeks (daily, 40 mg/kg i. p.), then subjected to a lethal dose of whole body γ-irradiation (from a ⁶⁰Co source). Survival was observed for 30 days after irradiation. Immune and mitochondrial dysfunction and oxidative damage were analyzed in mice with the same C₆₀(OH)₂₄ pretreatment and irradiation except that the animals were euthanized at day 5 after the irradiation. It was found that 2-week C₆₀(OH)₂₄ pretreatment effectively reduced whole body irradiation-induced mortality without apparent toxicity. C₆₀(OH)₂₄ pretreatment also showed significant protective effects against ionizing-radiation-induced decreases in immune and mitochondrial function and antioxidant defense in the liver and spleen. These results suggest that the polyhydroxylated fullerene derivative C₆₀(OH)₂₄ protects against ionizing-radiation-induced mortality, possibly by enhancing immune function, decreasing oxidative damage and improving mitochondrial function.     

Effects of human umbilical cord-derived mesenchymal stem cells on anterior chamber-associated immune deviation

Introduction of antigen into anterior chamber (AC) induces a deviant immune response termed anterior chamber-associated immune deviation (ACAID) that protects the eye from inflammatory destruction consequent to a systemic immune response. Mesenchymal stem cells (MSCs) can modulate a variety of immune responses. However, the effects of systemic administration of MSCs on ACAID have not been explored. In this study, C57BL/6 mice were inoculated with ovalbumin in the AC to induce ACAID, control group received AC injection of solvent alone. Immediately after the AC injection, the mice were injected through the tail vein with human Umbilical Cord-derived MSCs (hUC-MSC) or phosphate buffer saline. All animals were subcutaneously immunized with ovalbumin one week later. Delayed-type hypersensitivity assay was performed another week following immunization. The splenic monocytes were then isolated, cultured and stimulated with ovalbumin. Levels of IL-10, TGF-β, and IFN-γ in culture media were measured by ELISA. The frequencies of CD4⁺CD25⁺Foxp3⁺ and CD8⁺Foxp3⁺ regulatory T cells (Tregs) were determined by flow cytometry. The results showed that the AC inoculation of ovalbumin induced significantly less ear swelling than controls, confirming the establishment of ACAID. MSCs potentiated IL-10 and TGF-β production, further suppressed IFN-γ secretion from splenic monocytes in ACAID mice, and enhanced expansion of CD4⁺CD25⁺Foxp3⁺ and CD8⁺Foxp3⁺ Tregs isolated from the spleen of ACAID mice. Therefore, our study, for the first time, provides clear evidence that systemic administration of MSCs augments cytokine production and Treg expansion from ACAID spleens, which may contribute to promotion and maintenance of ACAID.     

Exploring the immunopotentiation of Chinese yam polysaccharide poly(lactic-co-glycolic acid) nanoparticles in an ovalbumin vaccine formulation in vivo

Biocompatible and biodegradable poly(lactic-co-glycolic acid) (PLGA) has been approved by the US Food and Drug Administration and has frequently been used to develop potential vaccine delivery systems. The immunoregulation and immunopotentiation of Chinese yam polysaccharide (CYP) have been widely demonstrated. In the current study, cell uptake mechanisms in dendritic cells (DCs) were monitored in vitro using confocal laser scanning microscopy, transmission electron microscopy, and flow cytometry. To study a CYP-PLGA nanoparticle-adjuvanted delivery system, CYP and ovalbumin (OVA) were encapsulated in PLGA nanoparticles (CYPPs) to act as a vaccine, and the formulation was tested in immunized mice. The CYPPs more easily underwent uptake by DCs in vitro, and CYPP/OVA could stimulate more effective antigen-specific immune responses than any of the single-component formulations in vivo. Mice immunized using CYPP/OVA exhibited more secretion of OVA-specific IgG antibodies, better proliferation, and higher cytokine secretion by splenocytes and significant activation of CD3⁺CD4⁺ and CD3⁺CD8⁺ T cells. Overall, the CYPP/OVA formulation produced a stronger humoral and cellular immune response and a mixed Th1/Th2 immune response with a greater Th1 bias in comparison with the other formulations. In conclusion, the data demonstrate that the CYPP-adjuvanted delivery system has the potential to strengthen immune responses and lay the foundation for novel adjuvant design.     

丹参酮Ⅱ-A磺酸钠的药理研究

丹参酮Ⅱ-A磺酸钠(丹参201)是丹参酮Ⅱ-A的新水溶性衍生物。临床试用中对冠心病心绞痛和胸闷的症状有一定疗效,并能改善缺血性心电图。本文进行了丹参201对小鼠缺氧、狗心脏血流动力作用和小鼠体内代谢的研究。腹腔注射200 mg/kg,可显著的延长小鼠在缺氧情况下的存活时间;氧耗速度较对照组稍减慢;其死亡时余存氧含量亦较对照组为低(P<0.05)。小鼠缺氧达到氧含量为6%时,心脏和脑组织中乳酸含量较正常组显著增加,而给丹参201后半小时再进行缺氧实验,组织中乳酸含量不增加,与正常组差异不显著。麻醉狗,一次静脉推注20 mg/kg,出现轻度血压升高,心输出量和左心室作功量稍有增加,心率和外周血管阻力的变化不显著。小鼠静注³⁵S-丹参201后2分钟血中放射活性为75843 cpm/0.1 ml,90分钟已降至3785 cpm/0.1 ml。注后1小时,以肝、肺和肠中放射活性为高;肾、脾、心和胃次之。6和24小时均趋减少。肠内容物中的放射活性在不同时间内均占首位。胆囊中亦较多。24小时内尿和粪中排泄率分别为10.2%和32.0%;24～48小时内分别为4.5%和24.1%;48～72小时内分别为1.8%和19.6%。经非放射性和放射性薄层层析及放射自显影证明,由尿中排出的代谢物,一个为丹参201的原型,另一个为代谢产物,其基本骨架与原型相似,看来是增加了某些极性基团。     

RETRACTED: Pierisformoside B exhibits neuroprotective and anti-inflammatory effects in murine hippocampal and microglial cells via the HO-1/Nrf2-mediated pathway

Ideal potential vaccine adjuvants to stimulate a Th1 immune response are urgently needed to control intracellular infections in clinical applications. Telocinobufagin (TBG), an active component of Venenum bufonis, exhibits immunomodulatory activity. Therefore, we investigated whether TBG enhances the Th1 immune response to ovalbumin (OVA) and formalin-inactivated Salmonella typhimurium (FIST) in mice. TBG augmented serum OVA- and FIST-specific IgG and IgG2a and the production of IFNγ by antigen-restimulated splenocytes. TBG also dramatically enhanced splenocyte proliferative responses to concanavalin A, lipopolysaccharide, and OVA and substantially increased T-bet mRNA levels and the CD3⁺/CD3⁺CD4⁺/CD3⁺CD8⁺ phenotype in splenocytes from OVA-immunized mice. In in vivo protection studies, TBG significantly decreased the bacterial burdens in the spleen and prolonged the survival time of FIST-immunized mice challenged with live S. typhimurium. In vivo neutralization of IFNγ with anti-IFNγ mAbs led to a significant reduction in FIST-specific IgG2a and IFNγ levels and in anti-Salmonella effect in TBG/FIST-immunized mice. In conclusion, these results suggest that TBG enhances a Th1 immune response to control intracellular infections.     

Adenosine receptor agonists attenuate and adenosine receptor antagonists exacerbate opiate withdrawal signs

Previous studies have demonstrated a role for adenosine in mediating opiate effects. Adenosine receptors and their functions have been shown to be regulated by chronic opiate treatment. This study examines the role of adenosine receptors in the expression of opiate withdrawal behaviors. The effects of single doses of parenterally administered adenosine receptor subtype-selective agonists and antagonists on opiate withdrawal signs in morphine-dependent mice were measured. Mice received subcutaneous morphine pellet treatment for 72 h and then underwent naloxone-precipitated withdrawal after pretreatment with adenosinergic agents. Adenosine agonists attenuated different opiate withdrawal signs. The A₁ agonistR-N ⁶(phenylisopropyl)adenosine (0, 0.01, 0.02 mg/kg, IP) significantly reduced wet dog shakes and withdrawal diarrhea, while the A_2a-selective agonist 2-p-(2-carboxethyl) phenylethylamino-5'-N-ethylcarboxamidoadenosine or CGS 21680 (0, 0.01, 0.05 mg/kg, IP) significantly inhibited teeth chattering and forepaw treads. Adenosine receptor antagonists enhanced different opiate withdrawal signs. The adenosine A₁ antagonist 1,3-dipropyl-8-cyclopentylxanthine (0, 1, 10 mg/kg, IP) significantly increased weight loss and the A₂ antagonist, 3,7-dimethyl-1-propargylxanthine (0, 1 and 10 mg/kg, IP) enhanced wet dog shakes and withdrawal diarrhea. Treatment effects of adenosinergic agents were not due to nonspecific motor effects, as demonstrated by activity monitoring studies. These results support a role for adenosine receptors in the expression of opiate withdrawal and suggest the potential utility of adenosine agonists in its treatment.Abstracts were presented at meetings of the Fifth International Symposium on Adenosine and Adenine Nucleotides in Philadelphia, Pa, May 9–13, 1994 and Society for Neuroscience in Miami Beach, FLa., November 13–18, 1994     

Enhancement of etorphine brain concentrations and changes in etorphine-naloxone pA2; values in morphine-pretreated mice

We had shown earlier that pretreatment of mice with a single dose of morphine sulfate enhanced the concentration of naloxone in the brain, and, therefore, the effect of this pretreatment on brain disposition of the narcotic agonist etorphine was examined for similar effects. Three hours after pretreatment with morphine, [³H]etorphine was administered subcutaneously, and its brain concentrations were determined as a function of time. Etorphine brain concentrations were higher in morphinethan in saline-pretreated animals at 5, 15, 20 and 30 min. This enhancement of brain concentrations was not associated with a change in the analgesic ED₅₀ for etorphine. Morphine pretreatment in mice has been reported by others to increase the affinity of the antagonist receptor site for naloxone, as demonstrated by an increase in the in vivo apparent pA₂ value for a morphine-naloxone interaction. In the present study, the morphine pretreatment decreased the etorphine-naloxone apparent pA₂ value in the direction opposite to that observed for the morphine-naloxone interaction. The results are discussed relative to a morphine-induced change in the disposition of etorphine in the brain, or to a morphine-induced alteration in morphine, etorphine and naloxone interactions at agonist and antagonist binding sites.     

Biphasic lipid vesicles as a subcutaneous delivery system for protein antigens and CpG oligonucleotides

One of the major drawbacks to the development of novel vaccines has been the lack of safe yet effective adjuvants. Biphasic lipid vesicles are formulations suitable for the delivery of proteins, peptides and oligo/polynucleotides. They constitute a new class of delivery system into which antigens and adjuvants can be incorporated. The purpose of these studies was to investigate the ability of biphasic lipid vesicles (Vaccine-Targeting Adjuvants--VTA) to induce immune responses to bacterial antigens and to enhance the adjuvant activity of CpG ODNs. Immunization of mice with bacterial antigen and CpG ODNs in saline was not as effective at inducing immune responses as formulation in VTA vesicles. Results showed that formulation of CpG ODN in VTA significantly enhanced its adjuvanticity.     

Pretreatment with a Water-Based Surfactant Formulation Affects Transdermal Iontophoretic Delivery of R-Apomorphine in Vitro

Purpose. To further increase the transdermal transport rate of R-apomorphine, a nonocclusive pretreatment with an aqueous surfactant formulation in combination with iontophoresis was explored in vitro. Methods. The human stratum corneum was pretreated nonocclusively with formulations composed of laureth-3 oxyethylene ether (C₁₂EO₃), laureth-7 oxyethylene ether (C₁₂EO₇), and cholesterol sulfate (CSO₄) prior to iontophoresis. The effect on the flux of the following parameters was examined: the composition, the charge, and the applied amount of surfactant formulations. Results. The iontophoretic flux of R-apomorphine was appreciably increased by pretreatment with surfactant formulations. A formulation containing C₁₂EO₃/C₁₂EO₇/CSO₄ at a molar ratio of 70:30:5 was very stable and increased the iontophoretic flux of R-apomorphine from 92.2 ± 13.9 nmol/cm²*h to 181.5 ± 22.6 nmol/cm²*h. When further increasing the negative charge of this formulation the iontophoretic transport rate was slightly inhibited. A dose of 40 L/cm² of the formulation with a total surfactant concentration of 5% (w/w) was sufficient for a maximum enhancing effect. Conclusions. The results obviously show that nonocclusive pretreatment with the surfactant formulation enhances the iontophoretic transport of R-apomorphine, and is a promising approach to achieve therapeutic concentrations of R-apomorphine.     

Prejunctional α-adrenoceptors regulate nitrergic neurotransmission in the rabbit urethra

We evaluated the effects of prejunctional α-adrenoceptors on nitric oxide (NO)-mediated urethral relaxation in rabbits using a muscle bath technique and high-performance liquid chromatography coupled with a microdialysis procedure. The amount of NO₂⁻/NO₃⁻ released during electrical field stimulation was measured by an NO₂⁻/NO₃⁻ analyzer based on the Griess method. Pretreatment with phenylephrine (0.01 μM) and yohimbine (0.1–10 μM) significantly reduced the relaxation responses induced by electrical field stimulation. In contrast, pretreatment with clonidine (0.01 μM) and prazosin (0.01–1 μM) enhanced the relaxation responses. Cys-NO-induced relaxations of rabbit urethral smooth muscle were not affected by pretreatment with α-adrenoceptor agonists and antagonists. The amount of NO₂⁻/NO₃⁻ released by electrical field stimulation increased after pretreatment with clonidine (0.01 μM) and prazosin (0.01–1 μM), but decreased after pretreatment with phenylephrine (0.01 μM) and yohimbine (0.1–10 μM). The results suggest that the release of NO from nitrergic nerves in the rabbit urethra is reduced and increased by stimulation of prejunctional α₁- and α₂-adrenoceptors, respectively.     

Central action of cesium chloride in streptozotocin-diabetic mice

The changes in the pharmacological responses to cesium were examined in streptozotocin(STZ)-induced diabetic mice. An acute administration of cesium chloride (10 mEqCs⁺/kg IP) to non-diabetic control mice elicited increased salivation and inhibition of respiration followed by death in about half of the animals examined. These effects of cesium were diminished in STZ-diabetic mice. LD₅₀ for acute cesium was higher in STZ-diabetic mice (14.3 mEq/kg) than non-diabetic buffer controls (11.7 mEq/kg); however, subchronic administration of cesium did not decrease the LD₅₀ in STZ-diabetic mice. The sleeping time induced by pentobarbital was reduced in STZ-diabetic mice and the reduction of the pentobarbital-induced hypnosis was reversed by subchronic cesium pretreatment but not by acute cesium administration. Methamphetamine-induced mortality was increased in STZ-diabetic mice and acute administration of cesium decreased the toxicity in both control and diabetic mice. Inhibition of locomotor activity elicited by acute single injection of cesium chloride was observed in both STZ-diabetic and non-diabetic mice. These results indicate that responses to cesium as well as centrally-acting drugs are affected differentially in STZ-diabetic mice.     

Drug distribution and a pulmonary adverse effect of intraperitoneally administered doxorubicin niosomes in the mouse

Niosomes (non-ionic surfactant vesicles) prepared from C₁₆G₂ (a hexadecyl-diglycerol ether), and loaded with doxorubicin, were administered intraperitoneally to male AKR mice at dose levels of 0, 2.5, 5.0, and 10.0 mg kg^?1. Free drug was given at 10.0 mg kg^?1 by the intraperitoneal route. At a dose level of 10.0 mg kg^?1, peak doxorubicin levels in the central compartment were attained faster with the free drug than with the niosome formulation. However, the peak plasma levels were similar for the free drug and the niosome preparation at the 10 mg kg^?1 dose level. With doxorubicin administered as the niosome preparation by the intraperitoneal route at 2.5, 5.0, and 10.0 mg kg^?1, mean peak plasma concentrations of the drug showed a tendency to be dose-related although the differences were not significant. Over the 24 h period of the experiment, with doxorubicin at 10 mg kg^?1, the niosome formulation delivered significantly more drug to the plasma compartment than the free drug (p <0.05). When doxorubicin was given in niosomes at 2.5, 5.0 and 10.0 mg kg^?1 by the intraperitoneal route, the resulting levels of doxorubicin in cardiac tissue were not dose related and the differences not significant and, although the mean peak cardiac-tissue concentration was higher in animals receiving the free drug at 10.0 mg kg^?1 intraperitoneally than in mice given intaperitoneal doxorubicin niosomes at this dose level, the differences were again not significant. There were clinical signs of toxicity in mice given doxorubicin-containing niosomes intraperitoneally at 5.0 and 10.0 mg kg^?1, and at post-mortem an accumulation of fluid in the pleural cavity was evident. These changes were not seen in mice dosed intraperitoneally with free drug at 10 mg kg^?1, or in animals given doxorubicin niosomes intraperitoneally at 2.5 mg kg^?1. In mice dosed intraperitoneally with doxorubicin niosomes at 12.0 mg kg^?1 and at a dose volume of 0.2–0.4 mL, histological examination of the lungs demonstrated a congestion of the alveolar capillaries, and an increased number of acute inflammatory cells in the alveolar walls. There was no histological evidence of lung toxicity in mice dosed with doxorubicin niosomes at 12.0 mg kg^?1 when the formulation was administered with the higher dose volume of 1.8–2.0 mL. Importantly there was no histological evidence of lung toxicity in mice dosed with empty niosomes intraperitoneally or with doxorubicin niosomes given itravenously at 12.0 mg kg^?1.