Studies on Transdermal Delivery Enhancement of Zidovudine

The purpose of this study was to investigate physicochemical characteristics and in vitro release of zidovudine from monolithic film of Eudragit RL 100 and ethyl cellulose. Films included 2.5% or 5% (w/w) zidovudine of the dry polymer weight were prepared in various ratios of polymers by solvent evaporation method from methanol/acetone solvent mixture. The release studies were carried out by vertical Franz cells (2.2 cm² area, 20 ml receptor fluid). Ex vivo studies were done on Wistar rat skin within the films F6 (Eudragit RL100) and F7 (Eudragit RL100/Ethylcellulose, 1:1) consisting 5% (w/w) zidovudine in comparison with the same amount of free drug. Either iontophoresis (0.1 and 0.5 mA/cm² direct currents, Ag/AgCl electrodes) or dimethyl sulfoxide (pretreatment of 1% and 5%, w/w, solutions) were used as enhancers. Films consisting of ethyl cellulose under the ratio of 50% (w/w) gave similar release profiles, and the highest in vitro cumulative released amount was achieved with F6 film which gave the closest results with the free drug. This result could be due to the high swelling capacity and re-crystallization inhibition effect of RL 100 polymer which also influenced the film homogenization. All the films were fitted to Higuchi release kinetics. It was also observed that both 0.5-mA/cm² current and 5% (w/w) dimethyl sulfoxide applications significantly increased the cumulative permeated amount of zidovudine after 8 h; however, the flux enhancement ratio was higher for 0.5-mA/cm² current application, especially within F6 film. Thus, it was concluded that Eudragit RL100 film (F6) could be further evaluated for the transdermal application of zidovudine.     

Treg depletion inhibits efficacy of cancer immunotherapy: implications for clinical trials

Background

Regulatory T lymphocytes (Treg) infiltrate human glioblastoma (GBM); are involved in tumor progression and correlate with tumor grade. Transient elimination of Tregs using CD25 depleting antibodies (PC61) has been found to mediate GBM regression in preclinical models of brain tumors. Clinical trials that combine Treg depletion with tumor vaccination are underway to determine whether transient Treg depletion can enhance anti-tumor immune responses and improve long term survival in cancer patients.

Findings

Using a syngeneic intracrabial glioblastoma (GBM) mouse model we show that systemic depletion of Tregs 15 days after tumor implantation using PC61 resulted in a decrease in Tregs present in tumors, draining lymph nodes and spleen and improved long-term survival (50% of mice survived >150 days). No improvement in survival was observed when Tregs were depleted 24 days after tumor implantation, suggesting that tumor burden is an important factor for determining efficacy of Treg depletion in clinical trials. In a T cell dependent model of brain tumor regression elicited by intratumoral delivery of adenoviral vectors (Ad) expressing Fms-like Tyrosine Kinase 3 ligand (Flt3L) and Herpes Simplex Type 1-Thymidine Kinase (TK) with ganciclovir (GCV), we demonstrate that administration of PC61 24 days after tumor implantation (7 days after treatment) inhibited T cell dependent tumor regression and long term survival. Further, depletion with PC61 completely inhibited clonal expansion of tumor antigen-specific T lymphocytes in response to the treatment.

Conclusions

Our data demonstrate for the first time, that although Treg depletion inhibits the progression/eliminates GBM tumors, its efficacy is dependent on tumor burden. We conclude that this approach will be useful in a setting of minimal residual disease. Further, we also demonstrate that Treg depletion, using PC61 in combination with immunotherapy, inhibits clonal expansion of tumor antigen-specific T cells, suggesting that new, more specific targets to block Tregs will be necessary when used in combination with therapies that activate anti-tumor immunity.     

Ghrelin: Impact on Muscle Energy Metabolism in Sepsis

We investigated the effects of exogenous ghrelin on energy levels and tissue histology in skeletal muscle in experimentally lipopolysaccharide (LPS) induced septic rats. Male Wistar albino rats 200–250 g were separated into four groups; Control, LPS (5 mg/kg), Ghrelin (10 nmol/kg i.v.), and ghrelin+LPS. Gastrocnemius muscle tissue was taken and stained using modified Gomori trichrome (MGT), succinic dehydrogenase (SDH), and cytochrome oxidase (COX) and hematoxylin and eosin. In stained sections, histological score value was calculated according to the intensity and the distribution for MGT, SDH and COX stainings. Creatine, creatine phosphate, adenosine triphosphate (ATP), adenosine monophosphate (AMP) levels, and the ratios of AMP/ATP and CreaP/ATP were investigated using high performance liquid chromatography (HPLC) in muscle tissue. Significances between experimental groups were calculated with an analysis of variance (ANOVA) followed by Tukey’s tests. Myopathic changes were seen in the 50% of rats in the LPS group as rounding of muscle fibers and fiber size variation. In the ghrelin+LPS group, ghrelin treatment was reduced damage in skeletal muscle structure. There was no change in creatine or AMP levels between the groups. Ghrelin treatment significantly increased ATP values (P?<?0.01) and improved tissue histology in septic rats. Ratios of both AMP/ATP and CreaP/ATP were found increased in the septic group, but there were decreaments in both the ghrelin and ghrelin-treated septic groups. Ghrelin could play an important role in energy balance and muscle morphology in skeletal muscle during sepsis.     

Optimization of poly(β-hydroxybutyric acid) recovery from Alcaligenes latus: combined mechanical and chemical treatments

Recovery of the intracellular bioplastic poly(β-hydroxybutyric acid) or PHB from fed-batch cultured Alcaligenes latus, ATCC 29713, was examined using combinations of chemical and mechanical treatments to disrupt the cells. Chemical pretreatments used sodium chloride and sodium hydroxide. For salt pretreatment the cells were exposed to NaCl (8?kg?m^?3) and heat (60?°C, 1 h), cooled to 4?°C, and mechanically disrupted. For alkaline treatments, the cells were exposed to sodium hydroxide (0.025–0.8 kg?NaOH per kg biomass) and mechanically disrupted at ambient temperature. A combined treatment with sodium chloride (8 kg m^?3), heat (60?°C, 1 h), and alkaline pH shock (pH 11.5, 1?min) was also tested. Mechanical disruption employed a continuous flow bead mill (2,800 rpm agitation speed, 90?ml?min^?1 slurry flow rate, 512 m mean bead diameter, bead loadings of 80% or 85% of chamber volume). Disruption was quantified by protein release. Over most of the disruption period, the release of PHB was approximately proportional to protein release. Regardless of the pretreatment or bead load, the disruption obeyed first order kinetics; hence, the rate of protein release was directly proportional to the amount of unreleased protein. Relative to untreated biomass, pretreatment always produced earlier protein release during milling. Pretreatment with a minimum of 0.12?kg NaOH per kg biomass was necessary to enable complete disruption within three passes (85% bead load). Untreated biomass required more than twice as many passes. Irrespective of the chemical pretreatment, the bead loading strongly influenced the disruption rate which was higher at the higher loading. Alkaline hydrolysis associated PHB loss was observed, but it could be limited to insignificant levels by immediate neutralization of disrupted homogenates.     

Organization and nucleotide sequence of the 3' end of the human CAD gene

Aspartate transcarbamylase (ATCase) is found as a monofunctional protein in prokaryotes and as a part of a multifunctional protein in fungi and animals. In mammals, this enzyme along with carbamyl phosphate synthetase II and dihydroorotase (DHOase) is encoded by a single gene called CAD. To determine the relationship between gene structure and the enzymatic domains of human CAD, we have isolated genomic clones of the human gene and sequenced the region corresponding to the 3' end of the gene. This includes exons encoding the end of the domain for DHOase, the complete domain for ATCase, and the bridge region connecting the two enzymatic domains. Three findings emerged. First, in comparing the human coding sequence to that obtained for other species that have a CAD gene, the length of the bridge region is conserved but its sequence is not. This is in contrast to the strong degree of positional identity observed for the segments of CAD encoding the DHOase and ATCase domains. Second, sets of exons appear to correspond to specific domains and subdomains of the encoded protein. Third, while overall there is a strong conservation of protein sequence among the ATCases of all species, reflecting conservation in catalytic function, two particular regions of the enzyme are more highly conserved among species where ATCase is a domain of a multifunctional protein as opposed to species where it is a monofunctional protein. Such findings may indicate regions of the ATCase domain that provide important structural contacts or functional channels when part of a multifunctional protein.     

Monoterpene biosynthesis in lemon (Citrus limon). cDNA isolation and functional analysis of four monoterpene synthases.

Citrus limon possesses a high content and large variety of monoterpenoids, especially in the glands of the fruit flavedo. The genes responsible for the production of these monoterpenes have never been isolated. By applying a random sequencing approach to a cDNA library from mRNA isolated from the peel of young developing fruit, four monoterpene synthase cDNAs were isolated that appear to be new members of the previously reported tpsb family. Based on sequence homology and phylogenetic analysis, these sequences cluster in two separate groups. All four cDNAs could be functionally expressed in Escherichia coli after removal of their plastid targeting signals. The main products of the enzymes in assays with geranyl diphosphate as substrate were (+)-limonene (two cDNAs) (-)-beta-pinene and gamma-terpinene. All enzymes exhibited a pH optimum around 7; addition of Mn(2+) as bivalent metal ion cofactor resulted in higher activity than Mg(2+), with an optimum concentration of 0.6 mm. K(m) values ranged from 0.7 to 3.1 microm. The four enzymes account for the production of 10 out of the 17 monoterpene skeletons commonly observed in lemon peel oil, corresponding to more than 90% of the main components present.     

Global phylogeography of the avian malaria pathogen Plasmodium relictum based on MSP1 allelic diversity

Knowing the genetic variation that occurs in pathogen populations and how it is distributed across geographical areas is essential to understand parasite epidemiology, local patterns of virulence, and evolution of host‐resistance. In addition, it is important to identify populations of pathogens that are evolutionarily independent and thus ‘free’ to adapt to hosts and environments. Here, we investigated genetic variation in the globally distributed, highly invasive avian malaria parasite Plasmodium relictum, which has several distinctive mitochondrial haplotyps (cyt b lineages, SGS1, GRW11 and GRW4). The phylogeography of P. relictum was accessed using the highly variable nuclear gene merozoite surface protein 1 (MSP1), a gene linked to the invasion biology of the parasite. We show that the lineage GRW4 is evolutionarily independent of GRW11 and SGS1 whereas GRW11 and SGS1 share MSP1 alleles and thus suggesting the presence of two distinct species (GRW4 versus SGS1 and GRW11). Further, there were significant differences in the global distribution of MSP1 alleles with differences between GRW4 alleles in the New and the Old World. For SGS1, a lineage formerly believed to have both tropical and temperate transmission, there were clear differences in MSP1 alleles transmitted in tropical Africa compared to the temperate regions of Europe and Asia. Further, we highlight the occurrence of multiple MSP1 alleles in GRW4 isolates from the Hawaiian Islands, where the parasite has contributed to declines and extinctions of endemic forest birds since it was introduced. This study stresses the importance of multiple independent loci for understanding patterns of transmission and evolutionary independence across avian malaria parasites.     

In vitro knock-out of miR-155 suppresses leukemic and HCV virus loads in pediatric HCV-4–associated acute lymphoid leukemia: A promising target therapy

Hepatitis C virus (HCV) infection is a major public health problem, having a high prevalence in Egypt. Leukemia and lymphoma have been associated with HCV infection. MicroRNA-155 (miR-155) has been reported to play a regulatory role in cancer, inflammation, and immune response to infection. The expression level of miR-155 in HCV viremic patients is controversial; although high miR-155 levels were demonstrated in HCV genotypes 1,2, and 3, low levels of miR-155 were detected in Egyptian patients with HCV genotype 4. Several studies have investigated the correlation between the levels of miRNA-155 and the replication of HCV, others have evaluated miRNA-155 as a prognostic biomarker in different types of cancer. No studies have investigated the impact of miRNA-155 knockdown on HCV pediatric patients associated with childhood acute lymphoblastic leukemia (ALL). We knocked-out the miR_155a in cultured polymorphonuclear cells (PBMCs) obtained from 60 children with ALL; 30 were associated with HCV-4 infection and 30 were HCV negative. The miR_155a, HCV viral load, and cell proliferation werre assessed in treated and untreated cells using TaqMan assay quantitative polymerase chain reaction. We found that miRNA-155 was significantly upregulated by seven folds in the HCV-4 associated ALL group; while being linked to high HCV viral load and leukemic burden, miR_155a knock-out can improve the disease outcome. We conclude that miR-155 is a critical miRNA that is considered a therapeutic target in pediatric HCV leukemic patients.     

Patterns of lipid biomarkers in the fruit of Bupleurum L. growing wild in Turkey

Four Bupleurum species, representing two sections, were collected from their natural habitats and the fatty acid and sterol compositions and α-tocopherol contents of their fruit oils examined. The major fatty acids were oleic, linoleic and palmitic acids in all species (41.13–79.92%, 11.07–23.21% and 3.52–7.60%, respectively). Δ-5-Avenasterol, stigmasterol, β-sitosterol, Δ-5,24-stigmastadienol and campesterol exhibited in significant concentrations in all species (9.63–48.79%, 15.42–33.44%, 16.11–25.35%, 12.67–22.97% and 3.10–4.86%, respectively). Higher α-tocopherol concentrations were quantified in both species from section Eubupleura (2.55–2.70 mg/100 g) than in section Perfoliata. Significant correlations were found among the fatty acid and phytosterol quantities observed in the Bupleurum accessions. The results indicated that these species have potential as alternative raw materials and nutraceutical sources through the selection of high yield cultivars and agricultural production.