Thiazolidinediones increase arachidonic acid release and subsequent prostanoid production in a peroxisome proliferator-activated receptor gamma-independent manner

Thiazolidinedione, peroxisome proliferator-activated receptor gamma (PPARgamma) agonist, has been used as an anti-diabetic drug and as an useful tool to elucidate multiple PPARgamma functions by in vitro and in vivo studies. We investigated the effects of thiazolidinediones on prostanoid production in lipopolysaccharide-stimulated cells. The high concentrations (>10 microM) of rosiglitazone and pioglitazone significantly increased lipopolysaccharide-stimulated prostanoid production such as thromboxane A2 and prostaglandin E2. However, PPARgamma antagonist could not inhibit them. In PPARgamma-deficient cells, thiazolidinediones increased prostaglandin E2 production. Thiazolidinediones increased arachidonic acid (AA) release from the cell membrane by not stimulating AA releasing process involving several phospholipase A2s but inhibiting AA reuptaking process. The expression of cyclooxygenase-1 and cyclooxygenase-2 were not affected by thiazolidinediones. In this study, we demonstrated that high concentrations of TZDs increased AA release by the inhibition of AA reuptaking process, leading to subsequent increase in the prostanoid production in a PPARgamma-independent manner. This mechanism provides useful information for the elucidation of multiple PPARgamma functions and diabetic drug therapy.     

Time course alterations of myocardial endothelin-1 production during the formation of exercise training-induced cardiac hypertrophy

Endothelin (ET)-1 is produced by endothelial cells and cardiac myocytes. ET-1 has positive inotropic and chronotropic effects on the heart and causes myocardial cell hypertrophy. Exercise training induces a physiologic cardiac hypertrophy. To study whether myocardial ET-1 is involved in the formation of exercise training-induced cardiac hypertrophy, we investigated time-course alterations of myocardial ET-1 gene expression and ET-1 peptide level in the heart of rats during a formative process of exercise training-induced cardiac hypertrophy. We used the hearts of rats that had been exercise-trained for 4 weeks (4WT) or 8 weeks (8WT) and sedentary control rats for 4 weeks (4WC) or 8 weeks (8WC). Exercise-trained rats performed treadmill running for 5 days/week (60 mins/day). Left ventricular mass index and wall thickness and stroke volume index, measured using echocardiography, in the 8WT group were significantly greater than in the 8WC group, although there were no differences between the 4WC and 4WT groups in these parameters. These results indicated that the 8WT rats developed physiologic cardiac hypertrophy, whereas the 4WT rats did not yet have cardiac hypertrophy. Myocardial ET-1 gene expression and tissue ET-1 concentration in the heart were significantly higher in the 8WT group than in the 8WC group, whereas these values did not differ between the 4WC and 4WT groups. The present study suggests that an alternation of myocardial ET-1 production corresponds with the formation of exercise training-induced cardiac hypertrophy. Therefore, the exercise training-induced change in myocardial ET-1 production may participate in a mechanism of exercise training-induced cardiac adaptation (e.g., cardiac hypertrophy).     

Novel preparation method for surfactant-coated enzymes using W/O emulsion

Summary A novel preparation method for surfactant-coated enzymes has been developed using a W/O emulsion. The enzymatic activity of chymotrypsin in isooctane significantly increased with the coating of surfactants. The surfactant-coated chymotrypsin showed a high enzymatic activity for amidation, although powdered chymotrypsin did not show the activity. Further, the coated enzyme showed a remarkably high storage stability.     

Annual changes in the testicular activity of the river sculpin, Cottus hangiongensis Mori, with emphasis on the occurrence of aberrant spermatids during spermatogenesis

Annual changes in the spermatogenetic activity of the testis were studied histologically in the river sculpin. Coitus hangiongensis , sampled monthly from a river in southern Hokkaido, Japan. A pair of sperm reservoirs, consisting of many anastomosing lacunae, was present along the dorsomedian edge of the paired testes, and functioned also as a sperm-transporting system instead of the typical sperm duct. Spermatogenesis occurred actively in August, yielding an increasing number of mature spermatozoa in October. This process advanced, but slowly during the succeeding winter months, until March. The testis became functionally mature during the spawning period in April and May. In July, small numbers of spermatocytes were found to have appeared already, which indicated a relatively short period of post-spawning testicular regression. In November, germinal cysts containing aberrant binuclear spermatids began to appear within the seminal lobules. The paired nuclei of aberrant spermatids gradually enlarged, and the cells were released into the lumina of the seminal lobules simultaneously with the release of mature spermatozoa from the germinal cysts. During the functional maturity stage, lumina of seminal lobules which had expelled mature spermatozoa to sperm reservoirs became filled with these abnormal bodies. Discussion includes the occurrence of aberrant spermatids which resulted in the formation of 'spermatid masses' as has been described in other cottids.     

Polymerization of Horseradish Peroxidase by a Laccase‐Catalyzed Tyrosine Coupling Reaction

The polymerization of proteins can create newly active and large bio‐macromolecular assemblies that exhibit unique functionalities depending on the properties of the building block proteins and the protein units in polymers. Herein, the first enzymatic polymerization of horseradish peroxidase (HRP) is reported. Recombinant HRPs fused with a tyrosine‐tag (Y‐tag) through a flexible linker at the N‐ and/or C‐termini are expressed in silkworm, Bombyx mori. Trametes sp. laccase (TL) is used to activate the tyrosine of Y‐tagged HRPs with molecular O₂ to form a tyrosyl‐free radical, which initiates the tyrosine coupling reaction between the HRP units. A covalent dityrosine linkage is also formed through a HRP‐catalyzed self‐crosslinking reaction in the presence of H₂O₂. The addition of H₂O₂ in the self‐polymerization of Y‐tagged HRPs results in lower activity of the HRP polymers, whereas TL provides site‐selectivity, mild reaction conditions and maintains the activity of the polymeric products. The cocrosslinking of Y‐tagged HRPs and HRP‐protein G (Y‐HRP‐pG) units catalyzed by TL shows a higher signal in enzyme‐linked immunosorbent assay (ELISA) than the genetically pG‐fused HRP, Y‐HRP‐pG, and its polymers. This new enzymatic polymerization of HRP promises to provide highly active and functionalized polymers for biomedical applications and diagnostics probes.     

Impact of Exercise and Moderate Hypoxia on Glycemic Regulation and Substrate Oxidation Pattern

Objective

We examined metabolic and endocrine responses during rest and exercise in moderate hypoxia over a 7.5 h time courses during daytime.

Methods

Eight sedentary, overweight men (28.6±0.8 kg/m²) completed four experimental trials: a rest trial in normoxia (FiO₂ = 20.9%, NOR-Rest), an exercise trial in normoxia (NOR-Ex), a rest trial in hypoxia (FiO₂ = 15.0%, HYP-Rest), and an exercise trial in hypoxia (HYP-Ex). Experimental trials were performed from 8:00 to 15:30 in an environmental chamber. Blood and respiratory gas samples were collected over 7.5 h. In the exercise trials, subjects performed 30 min of pedaling exercise at 60% of VO₂max at 8:00, 10:30, and 13:00, and rested during the remaining period in each environment. Standard meals were provided at 8:30, 11:00, and 13:30.

Results

The areas under the curves for blood glucose and serum insulin concentrations over 7.5 h did not differ among the four trials. At baseline, %carbohydrate contribution was significantly higher in the hypoxic trials than in the normoxic trials (P<0.05). Although exercise promoted carbohydrate oxidation in the NOR-Ex and HYP-Ex trials, %carbohydrate contribution during each exercise and post-exercise period were significantly higher in the HYP-Ex trial than in the NOR-Ex trial (P<0.05).

Conclusion

Three sessions of 30 min exercise (60% of VO₂max) in moderate hypoxia over 7.5 h did not attenuate postprandial glucose and insulin responses in young, overweight men. However, carbohydrate oxidation was significantly enhanced when the exercise was conducted in moderate hypoxia.     

Synthesis and biological evaluation of truncated α-galactosylceramide derivatives focusing on cytokine induction profile

A series of truncated analogs of α-galactosylceramide with altered ceramide moiety was prepared, and evaluated for Th2-biased response in the context of IL-4/IFN-γ ratio. Phytosphingosine-modified analogs including cyclic, aromatic and ethereal compounds as well as the C-glycoside analog of OCH (2) with their cytokine inducing profile are disclosed.     

Characterization of the cells in the repair tissue of full-thickness articular cartilage defects

 It is well established that a full-thickness articular cartilage defect is repaired with a fibrocartilaginous tissue, cells of which are derived from undifferentiated mesenchymal stem cells in the bone marrow. To characterize the repair cells biochemically, full-thickness defects were created in rabbit knee joints and the repair tissues taken at 3, 6, and 12 weeks after surgery. The repair cells were cultured and examined biochemically to investigate the effects of four exogenous growth factors with regard to the metabolism of type II collagen and proteoglycans. A significant increase of carboxy-terminal type II procollagen peptide production was observed in the conditional medium of the repair cells, especially taken at 6 weeks after surgery, in the presence of each growth factor. Glycosaminoglycan content was also increased and proteoglycan synthesis stimulated. The repair cells taken at the early stage of the repair process could originally have more activity of type II collagen synthesis, and the growth factors used could enhance the differentiation of the repair cells in vitro. Accepted: 3 November 1997     

Discriminative staining methods for the nervous system: luxol fast blue--periodic acid-Schiff--hematoxylin triple stain and subsidiary staining methods

This paper describes a new series of staining methods which can discriminatively demonstrate every structure of the nervous system, including axons and capillaries, in animal and human materials. Methods described in this paper consist of one primary stain, luxol fast blue-periodic acid Schiff-hematoxylin (LPH) and six different subsidiary staining methods. The LPH triple stain can precisely differentiate the following structures: neurons (Nissl bodies, cytoplasm, nuclear membrane and nucleolus), various kinds of nuclei (glia, ependyma, endothelium, leucocyte, connective tissue, etc.), myelin sheaths, neuronal processes (axons and dendrites), reacted glial cell bodies (protoplasmic astrocytes, foamy cells, etc.), blood vessels (arteries, veins and capillaries), meninges, intervening connective tissue, erythrocytes, lipofuscin granules, amyloid bodies, and others. Subsidiary staining methods are also described briefly. Applications are discussed in the context of staining technology and neuromorphological research.