Ammonium ion level in serum affects doxorubicin release from liposomes

In this study, we measured the release of drug from liposome-encapsulated doxorubicin (DXR) in human and mouse serum. While human serum did not induce DXR-release, mouse serum significantly induced DXR-release in a temperature- and time-dependent manner. Release of DXR was clearly observed in ultrafiltrated mouse serum, indicating that low-molecular substances affect DXR-release. Therefore, the level of Na+, Cl(-), NH4+, and urea nitrogen in each type of serum was measured. Only the concentration of NH4+ in mouse serum was significantly higher than that in human serum. Furthermore, addition of ammonium acetate to human serum induced DXR release at the same level observed in mouse serum. These results indicate that the NH4+ concentration in serum might greatly affect the release of DXR from liposomes.

Creation of an improved mutant TNF with TNFR1-selectivity and antagonistic activity by phage display technology

Tumor necrosis factor-alpha (TNF), which binds two types of TNF receptors (TNFR1 and TNFR2), regulates the onset and exacerbation of autoimmune diseases such as rheumatoid arthritis and Crohn's disease. In particular, TNFR1-mediated signals are predominantly related to the induction of inflammatory responses. We have previously generated a TNFR1-selective antagonistic TNF-mutant (mutTNF) and shown that mutTNF efficiently inhibits TNFR1-mediated bioactivity in vitro and attenuates inflammatory conditions in vivo. In this study, we aimed to improve the TNFR1-selectivity of mutTNF This was achieved by constructing a phage library displaying mutTNF-based variants, in which the amino acid residues at the predicted receptor binding sites were substituted to other amino acids. From this mutant TNF library, 20 candidate TNFR1-selective antagonists were isolated. Like mutTNF, all 20 candidates were found to have an inhibitory effect on TNFR1-mediated bioactivity. However, one of the mutants, N7, displayed significantly more than 40-fold greater TNFR1-selectivty than mutTNF. Therefore, N7 could be a promising anti-autoimmune agent that does not interfere with TNFR2-mediated signaling pathways.

Potential effects of climate change and variability on watershed biogeochemical processes and water quality in Northeast Asia

An overview is provided of the potential effects of climate change on the watershed biogeochemical processes and surface water quality in mountainous watersheds of Northeast (NE) Asia that provide drinking water supplies for large populations. We address major 'local' issues with the case studies conducted at three watersheds along a latitudinal gradient going from northern Japan through the central Korean Peninsula and ending in southern China. Winter snow regimes and ground snowpack dynamics play a crucial role in many ecological and biogeochemical processes in the mountainous watersheds across northern Japan. A warmer winter with less snowfall, as has been projected for northern Japan, will alter the accumulation and melting of snowpacks and affect hydro-biogeochemical processes linking soil processes to surface water quality. Soils on steep hillslopes and rich in base cations have been shown to have distinct patterns in buffering acidic inputs during snowmelt. Alteration of soil microbial processes in response to more frequent freeze-thaw cycles under thinner snowpacks may increase nutrient leaching to stream waters. The amount and intensity of summer monsoon rainfalls have been increasing in Korea over recent decades. More frequent extreme rainfall events have resulted in large watershed export of sediments and nutrients from agricultural lands on steep hillslopes converted from forests. Surface water siltation caused by terrestrial export of sediments from these steep hillslopes is emerging as a new challenge for water quality management due to detrimental effects on water quality. Climatic predictions in upcoming decades for southern China include lower precipitation with large year-to-year variations. The results from a four-year intensive study at a forested watershed in Chongquing province showed that acidity and the concentrations of sulfate and nitrate in soil and surface waters were generally lower in the years with lower precipitation, suggesting year-to-year variations in precipitation as a key factor in modulating the effects of acid deposition on soil and surface water quality of this region. Results from these case studies suggest that spatially variable patterns of snow or summer precipitation associated with regional climate change across NE Asia will have significant impacts on watershed biogeochemical processes and surface water quality, in interactions with local topography, land use change, or acid deposition.

RAFT-generated polyacrylamide-DNA block copolymers for single-nucleotide polymorphism genotyping by affinity capillary electrophoresis

Capillary electrophoretic separation of a mixture of 5'-fluorescein isothiocyanate-labeled single-stranded DNA (normal ssDNA) and its single-base-substituted one (mutant ssDNA) was achieved by using a RAFT-generated polyacrylamide-oligodeoxyribonucleotide block copolymer (PAAm-b-ODN) as an affinity polymeric probe. PAAm-b-ODN was synthesized through the Michael addition of thiol-terminated PAAm (PAAm-SH) to 5'-maleimide-modified ODN. PAAm-SH was derived from dithiobenzoate-terminated PAAm prepared via RAFT polymerization. The number-averaged molecular weight (M(n)) and the molecular weight distribution were determined by aqueous size exclusion chromatography. After a capillary tube was filled with the running buffer solution of PAAm-b-ODN, a mixture of normal and mutant ssDNA was subjected to electrophoresis and detected by a laser-induced fluorescent detector. Because the base sequence of PAAm-b-ODN was complementary to part of the mutant ssDNA, including a single-base substitution site, the electrophoretic migration of mutant ssDNA was retarded due to the formation of the equilibrium complex with PAAm-b-ODN. Increasing M(n) of the PAAm segment enhanced this retardation. On the other hand, normal ssDNA was unable to form the complex owing to a single-base mismatch, which was proved by melting curve measurements. The Lineweaver-Burk-type analysis of the mobility of mutant ssDNA revealed that the binding constants for the complexes with different PAAm-b-ODN probes were almost identical to each other. The analysis also demonstrated that the ratio of the hydrodynamic radius of the complex to that of the free mutant ssDNA increased with increasing M(n) of the affinity polymeric probe's PAAm segment. This means that the PAAm segment indirectly provides mutant ssDNA with an additional hydrodynamic friction force via the affinity interaction of the ODN segment. Optimization of the salt concentration of the running buffer and the capillary temperature improved the resolution of the separation. This affinity polymeric probe will be useful for developing a simple and highly reliable single-nucleotide polymorphism genotyping method.

Phase I/II study of sequential therapy with irinotecan and S-1 for metastatic colorectal cancer

Background:

Both irinotecan (CPT-11) and S-1 are active against colorectal cancer; however, as S-1 is a prodrug of 5-fluorouracil (5-FU), 5-FU and its metabolites might inhibit the antitumour effect of CPT-11. Therefore, we designed a sequential combination, in which CPT-11 infusion was given on day 1 and S-1 was given orally at 80 mg m⁻² per day on days 3–16 every 3 weeks.

Methods:

Twelve patients entered the phase I study, and the recommended doses were determined as a CPT-11 dose of 150 mg m⁻² and an S-1 dose of 80 mg m⁻².

Results:

In all, 36 patients entered the phase II study, of whom 4 and 16 had complete and partial responses. The overall response rate was 55.6% (95% confidence interval, 38.1–72.1%), and median progression-free survival was 7.7 months (95% confidence interval, 4.8–12.6 months). Grade 3 neutropenia was the most common haematological toxicity and occurred in 6.5% of 215 treatment courses. Grade 3 non-haematological toxicities included anorexia (1.4%) and diarrhoea (0.9%). There was no grade 4 toxicity of any kind.

Conclusion:

Our results suggest that this regimen is convenient, safe and promising, compared with conventional regimens for patients with metastatic colorectal cancer.

Relationships among changes of serum leptin concentration, leptin mRNA expression in white adipose tissue (WAT), and WAT fat-cell size in female Japanese black bears (Ursus thibetanus japonicus)

As a first step to study the relationship between fat accumulation and reproductive success in Japanese black bears ( Ursus thibetanus japonicus Schlegel, 1857) with the focus on leptin, we determined leptin cDNA sequences in the bears. Next, we studied the possibility of white adipose tissue (WAT) as a leptin secretion source by observing the changes of leptin mRNA expression in WAT by semiquantitative real-time reverse transcript – polymerase chain reaction, the index of WAT fat-cell size, and serum leptin concentration in pregnant bears. Then, based on our results, we discussed roles of leptin in those bears. The amino acid sequences of leptin from the bears were highly identical to that of other carnivores. The expression of leptin mRNA in WAT was detected from September to January, with a tendency to increase in late November and January; the relationship between changes in the index of WAT fat-cell size and those in serum leptin concentration was high (r = 0.55, P < 0.01), with an increase in both in mid-November. These results suggested that leptin was mainly secreted from WAT in bears and that serum leptin concentrations might reflect their nutritional condition. Moreover, leptin might serve as an indicator of their fat mass, which would affect their survival during hibernation and their reproductive success.

Affinity capillary electrophoretic DNA separation using PEG-oligodeoxyribonucleotide block copolymers: relationship between peak resolution and affinity strength

Capillary electrophoretic separation of chemically synthesized ssDNA and a single-base-substituted one (normal and mutant ssDNA, respectively) was demonstrated using a PEG-oligodeoxyribonucleotide block copolymer (PEG-b-ODN) as an affinity ligand. When the base sequence of PEG-b-ODN was designed to be complementary to part of normal ssDNA including the base-substituted site, the electrophoretic mobility of normal ssDNA significantly decreased whereas that of mutant ssDNA slightly changed. Resolution of the separation strongly depended on the ODN length of the copolymer, the capillary temperature, and the Mg2+ concentration in the running buffer, indicating that the retardation of migration of normal ssDNA was induced by the reversible hybridization with PEG-b-ODN. It was found that the dissociation constant (K(d)) of the duplex between normal ssDNA and the affinity probe ODN should be smaller than 10(-6) M to achieve the good peak separation. In addition, we calculated the mobility of the complex (mu(C)) between normal ssDNA and PEG-b-ODN using a two-state model. The base sequence of affinity probe ODN appropriate to achieve the sufficient resolution will be predicted on the basis of the mu(C) and K(d )values.

Intracellular energy depletion triggers programmed cell death during petal senescence in tulip

Programmed cell death (PCD) in petals provides a model system to study the molecular aspects of organ senescence. In this study, the very early triggering signal for PCD during the senescence process from young green buds to 14-d-old petals of Tulipa gesneriana was determined. The opening and closing movement of petals of intact plants increased for the first 3 d and then gradually decreased. DNA degradation and cytochrome c (Cyt c) release were clearly observed in 6-d-old flowers. Oxidative stress or ethylene production can be excluded as the early signal for petal PCD. In contrast, ATP was dramatically depleted after the first day of flower opening. Sucrose supplementation to cut flowers maintained their ATP levels and the movement ability for a longer time than in those kept in water. The onset of DNA degradation, Cyt c release, and petal senescence was also delayed by sucrose supplementation to cut flowers. These results suggest that intracellular energy depletion, rather than oxidative stress or ethylene production, may be the very early signal to trigger PCD in tulip petals.

Point mutation assay by affinity capillary electrophoresis using poly(ethylene glycol)-oligodeoxyribonucleotide block copolymers

An affinity capillary electrophoresis was developed for detecting a point mutation of single-stranded DNA (ssDNA). Poly(ethylene glycol)-oligodeoxyribonucleo-tide block copolymers (PEG-b-ODN) were prepared to use as a novel affinity ligand. Optimization of the analytical conditions, such as the salt concentration of running buffer, the capillary temperature and the base number of the copolymer, gave two distinct peaks for wild-type (WT) and point-mutated ssDNA (MT) on the electropherogram, allowing for the facile discrimination of the single-base difference.

[Seasonal dynamics of hydrochemical characteristics of streams under different forest types]

Stream water samples under the Korean pine broad-leaved forest, spruce-fir forest, and larch plantation in Liangshui Nature Reserve of Xiaoxing' an Mountains were collected monthly from March to October 2006 to study the dynamic changes of their hydrochemical characteristics. The results indicated that the content of major cations in the streams was in the sequence of Ca2+ > Na+ > K+ > Mg2+, and that of anions was HCO3(-) > SO4(2-) > NO3(-) > Cl(-). The average content of Na+, Ca2+, Mg2+, Fe2+ and Fe3+ was in the order of spruce-fir forest > larch plantation > Korean pine broad-leaved forest, while that of K+ was in the order of larch plantation > spruce-fir forest > Korean pine broad-leaved forest. The average monthly content of anions in stream water was the highest under larch plantation.

Comparative study on transduction and toxicity of protein transduction domains

BACKGROUND AND PURPOSE

Protein transduction domains (PTDs), such as Tat, antennapedia homeoprotein (Antp), Rev and VP22, have been extensively utilized for intracellular delivery of biologically active macromolecules in vitro and in vivo. There is little known, however, about the relative transduction efficacy, cytotoxicity and internalization mechanism of individual PTDs.

EXPERIMENTAL APPROACH

We examined the cargo delivery efficacies of four major PTDs (Tat, Antp, Rev and VP22) and evaluated their toxicities and cell internalizing pathways in various cell lines.

KEY RESULTS

The relative order of the transduction efficacy of these PTDs conjugated to fluorescein was Rev>Antp>Tat>VP22, independent of cell type (HeLa, HaCaT, A431, Jurkat, MOLT-4 and HL60 cells). Antp produced significant toxicity in HeLa and Jurkat cells, and Rev produced significant toxicity in Jurkat cells. Flow cytometric analysis demonstrated that the uptake of PTD-fluorescein conjugate was dose-dependently inhibited by methyl-beta-cyclodextrin, cytochalasin D and amiloride, indicating that all four PTDs were internalized by the macropinocytotic pathway. Accordingly, in cells co-treated with 'Tat-fused' endosome-disruptive HA2 peptides (HA2-Tat) and independent PTD-fluorescent protein conjugates, fluorescence spread throughout the cytosol, indicating that all four PTDs were internalized into the same vesicles as Tat.

CONCLUSIONS AND IMPLICATIONS

These findings suggest that macropinocytosis-dependent internalization is a crucial step in PTD-mediated molecular transduction. From the viewpoint of developing effective and safe protein transduction technology, although Tat was the most versatile carrier among the peptides studied, PTDs should be selected based on their individual characteristics.

Creation of a novel cell penetrating peptide, using a random 18mer peptides library

Cell penetrating peptides (CPPs) have drawn attention as carriers for intracellular drug delivery. It is commonly believed that TAT peptide is the best carrier among the existing CPPs due to its high translocational activity. Despite considerable research, the cellular uptake mechanism of TAT peptide remains unclear. Additionally, the transduction efficiency of TAT peptide is insufficient for use in intracellular therapy. In this study, we attempted to identify novel CPPs from a random 18mer peptide library using a phage display system. To isolate novel CPPs more effectively, PSIF (protein synthesis inhibition factor) was used with the screening system. Consequently, we isolated 7 novel CPPs from the library and determined by flow cytometry and confocal laser microscopy that these CPPs were taken up into cells. Once the cellular uptake pathway of these CPPs has been determined, it may be possible to use them for intracellular therapy.

The contactin 4 gene locus at 3p26 is a candidate gene of SCA16

OBJECTIVE

To identify of the gene responsible for the onset of spinocerebellar ataxia type 16 (SCA16).

METHODS

We reanalyzed the linkage of the original Japanese pedigree using updated information, including three additional subjects. We then screened all exons located in the critical region.

RESULTS

We reassigned the locus of SCA16 to 3p26.2-pter (maximum logarithm-of-odds score = 5.177) and identified only one point mutation (4,256C-->T) in the 3' untranslated region of the contactin 4 gene (CNTN4) on chromosome 3p26.2-26.3, which cosegregated with the disease. This mutation was not detected in 520 control subjects; moreover, we revised the phenotype of SCA16 from pure to complicated SCA.

CONCLUSION

The contactin 4 gene (CNTN4) is associated with cerebellar degeneration in spinocerebellar ataxia type 16. Additional studies are necessary to prove 4,256C-->T to be a causative mutation.

Optimization of anti-tumor necrosis factor-alpha single chain Fv displayed on phages for creation of functional antibodies

In this study, we converted the immunoglobulin-type anti-human tumor necrosis factor-alpha (TNF-alpha) monoclonal antibody (Mab) to a scFv-type antibody in order to assess its basic properties. The immunoglobulin VH and VL genes were isolated from the hybridoma that produced an anti-TNF-alpha neutralizing Mab, and they were then linked together to create scFvs of the VL-VH or VH-VL-form. The binding affinity to TNF-a was retained in both scFvs. Interestingly, the VL-VH-type scFv effectively inhibited the TNF-alpha-mediated cytotoxicity, while this neutralization activity was dramatically decreased in the VH-VL-type scFv. These results suggest that the VL-VH-type scFv is a suitable template to create improved versions of the anti-TNF-alpha antibody using a phage display system, and they also show that the structural format must be taken into account in manufacturing scFvs.