Sustained release of an anti-glaucoma drug: demonstration of efficacy of a liposomal formulation in the rabbit eye

Topical medication remains the first line treatment of glaucoma; however, sustained ocular drug delivery via topical administration is difficult to achieve. Most drugs have poor penetration due to the multiple physiological barriers of the eye and are rapidly cleared if applied topically. Currently, daily topical administration for lowering the intra-ocular pressure (IOP), has many limitations, such as poor patient compliance and ocular allergy from repeated drug administration. Poor compliance leads to suboptimal control of IOP and disease progression with eventual blindness. The delivery of drugs in a sustained manner could provide the patient with a more attractive alternative by providing optimal therapeutic dosing, with minimal local toxicity and inconvenience. To investigate this, we incorporated latanoprost into LUVs (large unilamellar vesicles) derived from the liposome of DPPC (di-palmitoyl-phosphatidyl-choline) by the film hydration technique. Relatively high amounts of drug could be incorporated into this vesicle, and the drug resides predominantly in the bilayer. Vesicle stability monitored by size measurement and DSC (differential scanning calorimetry) analysis showed that formulations with a drug/lipid mole ratio of about 10% have good physical stability during storage and release. This formulation demonstrated sustained release of latanoprost in vitro, and then tested for efficacy in 23 rabbits. Subconjunctival injection and topical eye drop administration of the latanoprost/liposomal formulation were compared with conventional daily administration of latanoprost eye drops. The IOP lowering effect with a single subconjunctival injection was shown to be sustained for up to 50 days, and the extent of IOP lowering was comparable to daily eye drop administration. Toxicity and localized inflammation were not observed in any treatment groups. We believe that this is the first demonstration, in vivo, of sustained delivery to the anterior segment of the eye that is safe and efficacious for 50 days.     

A polysaccharide isolated from Cordyceps sinensis,a traditional Chinese medicine,protects PC12 cells against hydrogen peroxide-induced injury

Cordyceps sinensis, a well-known traditional Chinese medicine, possesses activities in anti-tumour, anti-oxidation and stimulating the immune system; however, the identity of active component(s) is not determined. By using anti-oxidation activity-guided fractionation, a polysaccharide of molecular weight approximately 210 kDa was isolated from cultured Cordyceps mycelia by ion-exchange and sizing chromatography. The isolated polysaccharide, having strong anti-oxidation activity, contains glucose, mannose and galactose in a ratio of 1 : 0.6 : 0.75. The pre-treatment of isolated polysaccharide on the cultured rat pheochromocytoma PC12 cells shows strong protective effect against hydrogen peroxide (H(2)O(2))-induced insult. Treatment of the cells with the isolated polysaccharide at 100 microg/ml prior to H(2)O(2) exposure significantly elevated the survival of PC12 cells in culture by over 60%. In parallel, the H(2)O(2)-induced production of malondialdehyde in cultured cells was markedly reduced by the polysaccharide treatment. Moreover, the pre-treatment of the isolated polysaccharide significantly attenuated the changes of glutathione peroxidase and superoxide dismutase activities in H(2)O(2)-treated cells in a dose-dependent manner. This is the first report in identifying a polysaccharide from Cordyceps, which protects against the free radical-induced neuronal cell toxicity.     

Prenylated flavanones and flavanonols as chemical markers in Glycosmis species (Rutaceae)

Fifteen prenylated or geranylated flavanones and flavanonols were isolated from the leaf extracts of different Glycosmis species collected in Thailand and Malaysia. All structures were elucidated by spectroscopic methods, especially 1D and 2D NMR. Six compounds were described for the first time and two were only known so far as synthetic products. The chemotaxonomic significance of flavanoid accumulation within the genus Glycosmis is highlighted.     

Combinatorial pathway analysis for improved L-tyrosine production in Escherichia coli: identification of enzymatic bottlenecks by systematic gene overexpression

Combinatorial overexpression of aromatic amino acid biosynthesis (AAAB) genes in the L-tyrosine producing Escherichia coli strains T1 and T2 was employed to search for AAAB reactions limiting L-tyrosine production. All AAAB genes except aroG and tyrA, which were substituted by their feedback resistant derivatives in the host strains, were cloned and overexpressed. A total of 72 different strains overexpressing various AAAB gene combinations were generated and from those strains with improved phenotype, enzymatic bottlenecks of the AAAB pathway could be inferred. The two major gene overexpression targets for increased L-tyrosine production in E. coli were ydiB and aroK, coding for a shikimate dehydrogenase and a shikimate kinase, respectively, and the combination of ydiB and aroK for overexpression resulted in the best L-tyrosine producing strains in this study, yielding 45% for strain T1 and 26% for strain T2, respectively, higher L-tyrosine titers. Interestingly, overexpression studies with combinations of more than one gene revealed that new gene targets could be identified when overexpessed together with other genes but not alone as single gene overexpression. For example, tyrB encoding the last enzyme of the AAAB pathway, an aromatic amino acid transaminase, improved L-tyrosine production significantly when co-overexpressed together with ydiB or aroK, but not when overexpressed alone. It is also noteworthy that E. coli T1, which generally yielded less L-tyrosine, was amenable to greater improvements than strain T2, i.e. E. coli T1 exhibited generally more space for phenotype improvement.     

Corticosteroid-induced abnormality in fetal mice and H-2 haplotype: Evidence of a cytoplasmic effect

Different strains of H-2 congenic mice have different susceptibilities to corticosteroid-induced fetal loss and cleft palate. Applying this knowledge, we tested the null hypothesis, which assumes that there are no statistically significant differences in the frequency of abnormality among various types of treated backcross offspring and, thus, no evidence of a cytoplasmic effect. In the present study this null hypothesis was frequently, but not consistently, rejected. Therefore, there was some evidence of a cytoplasmic effect. One possible explanation of these results is seen when one considers the phenotypic effects of “gene-gene interaction” between variant H-2 genotypes and an invariant mitochondrial genotype.     

Screening of the Antarctic marine sponges (Porifera) as a source of bioactive compounds

Sponges (Porifera) currently represent one of the richest sources of natural products and account for almost half of the pharmacologically active compounds of marine origin. However, to date very little is known about the pharmacological potential of the sponges from polar regions. In this work we report on screening of ethanolic extracts from 24 Antarctic marine sponges for different biological activities. The extracts were tested for cytotoxic effects against normal and transformed cell lines, red blood cells, and algae, for modulation of the activities of selected physiologically important enzymes (acetylcholinesterase, butyrylcholinesterase, and α-amylase), and for inhibition of growth of pathogenic and ecologically relevant bacteria and fungi. An extract from Tedania (Tedaniopsis) oxeata was selectively cytotoxic against the cancer cell lines and showed growth inhibition of all of the tested ecologically relevant and potentially pathogenic fungal isolates. The sponge extracts from Isodictya erinacea and Kirkpatrickia variolosa inhibited the activities of the cholinesterase enzymes, while the sponge extracts from Isodictya lankesteri and Inflatella belli reduced the activity of α-amylase. Several sponge extracts inhibited the growth of multiresistant pathogenic bacterial isolates of different origins, including extended-spectrum beta-lactamase and carbapenem-resistant strains, while sponge extracts from K. variolosa and Myxilla (Myxilla) mollis were active against a human methicillin-resistant Staphylococcus aureus strain. We conclude that Antarctic marine sponges represent a valuable source of biologically active compounds with pharmacological potential.     

By Regulating Mitochondrial Ca2+-Uptake UCP2 Modulates Intracellular Ca2+

Introduction

The possible role of UCP2 in modulating mitochondrial Ca²⁺-uptake (mCa²⁺-uptake) via the mitochondrial calcium uniporter (MCU) is highly controversial.

Methods

Thus, we analyzed mCa²⁺-uptake in isolated cardiac mitochondria, MCU single-channel activity in cardiac mitoplasts, dual Ca²⁺-transients from mitochondrial ((Ca²⁺)m) and intracellular compartment ((Ca²⁺)c) in the whole-cell configuration in cardiomyocytes of wild-type (WT) and UCP2^-/- mice.

Results

Isolated mitochondria showed a Ru360 sensitive mCa²⁺-uptake, which was significantly decreased in UCP2^-/- (229.4±30.8 FU vs. 146.3±23.4 FU, P<0.05). Single-channel registrations confirmed a Ru360 sensitive voltage-gated Ca²⁺-channel in mitoplasts, i.e. mCa1, showing a reduced single-channel activity in UCP2^-/- (Po,total: 0.34±0.05% vs. 0.07±0.01%, P<0.05). In UCP2^-/- cardiomyocytes (Ca²⁺)m was decreased (0.050±0.009 FU vs. 0.021±0.005 FU, P<0.05) while (Ca²⁺)c was unchanged (0.032±0.002 FU vs. 0.028±0.004 FU, P>0.05) and transsarcolemmal Ca²⁺-influx was inhibited suggesting a possible compensatory mechanism. Additionally, we observed an inhibitory effect of ATP on mCa²⁺-uptake in WT mitoplasts and (Ca²⁺)m of cardiomyocytes leading to an increase of (Ca²⁺)c while no ATP dependent effect was observed in UCP2^-/-.

Conclusion

Our results indicate regulatory effects of UCP2 on mCa²⁺-uptake. Furthermore, we propose, that previously described inhibitory effects on MCU by ATP may be mediated via UCP2 resulting in changes of excitation contraction coupling.     

A feruloyl esterase derived from a leachate metagenome library

A feruloyl esterase encoding gene (designated fae6), derived from a leachate metagenomic library, was cloned and the nucleotide sequence of the insert DNA determined. Translational analysis revealed that fae6 consists of a 515 amino acid polypeptide, encoding a 55 kDa pre-protein. The Fae6 primary structure contained the G-E-S-A-G sequence, which corresponds well with a typical catalytic serine sequence motif (G-x-S-x-G). The fae6 gene was successfully over-expressed in E. coli and the recombinant protein was purified to 8.4 fold enrichment with 17% recovery. The K(M) data showed Fae6 has a high affinity to methyl sinapate while thermostability data indicated that fae6 was thermolabile with a half life (T(1/2)) < 30 min at 50°C. High affinity for Fae6 against methyl sinapate, methyl ferulate and ethyl ferulate suggest that the enzyme can be useful in hydrolyzing ferulated polysaccharides in a biorefinery process.     

Manipulation of Cell:Cell Contacts and Mesoderm Suppressing Activity Direct Lineage Choice from Pluripotent Primitive Ectoderm-Like Cells in Culture

In the mammal, the pluripotent cells of embryo differentiate and commit to either the mesoderm/endoderm lineages or the ectoderm lineage during gastrulation. In culture, the ability to direct lineage choice from pluripotent cells into the mesoderm/endoderm or ectoderm lineages will enable the development of technologies for the formation of highly enriched or homogenous populations of cells. Here we show that manipulation of cell:cell contact and a mesoderm suppressing activity in culture affects the outcome of pluripotent cell differentiation and when both variables are manipulated appropriately they can direct differentiation to either the mesoderm or ectoderm lineage. The disruption of cell:cell contacts and removal of a mesoderm suppressor activity results in the differentiation of pluripotent, primitive ectoderm-like cells to the mesoderm lineage, while maintenance of cell:cell contacts and inclusion, within the culture medium, of a mesoderm suppressing activity results in the formation of near homogenous populations of ectoderm. Understanding the contribution of these variables in lineage choice provides a framework for the development of directed differentiation protocols that result in the formation of specific cell populations from pluripotent cells in culture.