Development of a diet for long-term raising of F344 rats--relationship between dietary digestible crude protein content and digestible energy content.

Mice and rats are frequently subjected to long-term raising in studies of aging. These animals are usually given growing or breeding diets from a young age. This raising method causes diseases such as chronic nephropathy with proteinuria due to nutritional excess. Consequently, a long-term raising study on male F344/DuCrj rats using nine sorts of diets differing in crude protein (CP; 12, 28, 44%) and digestible energy (DE; 2.8, 3.7, 4.5 kcal/g) contents was carried out. It was found that feed consumption was regulated by DE, not digestible crude protein (DCP) intake. Body weight was controlled within low energy areas, and was not influenced by feed or DCP intake. The liver and kidney weight at 105 weeks of age increased in response to an increase in the level of CP in the diet. Chronic nephropathy was severe in rats fed high protein diets and moderate levels of protein with moderate to high energy diets. Fatty liver and bile duct hyperplasia were found in rats fed a high protein and high energy diet. Few pathological findings of kidney and liver were found in the low protein and low energy diet group. The reduction of disorders attributable to excess energy or inappropriate diet suggests that low protein and low energy diets are most suitable for long-term raising in this strain of rat.     

Two new species of pyrenomycetous ascomycetes from New Caledonia

Two new species of Pyrenomycetes from forest soil in New Caledonia,Anthostomella pacifica andChaetomium novaecaledonicum, are described and illustrated.Anthostomella pacifica is characterized by non-ostiolate ascomata, cylindrical asci with an amyloid apical apparatus, and two-celled ascospores (dark apical cylindrical and hyaline basal dwarfed cells) with longitudinal germ slits.Chaetomium novae-caledonicum is characterized by ostiolate ascomata, straight terminal hairs, arcuate lateral hairs with a recurved tip, and very small, ovoid-flattened ascospores.This research was supported in part by Monbusho International Scientific Research Program: Field Research, No. 05041093.     

Deletion of ribosomal S6 kinases does not attenuate pathological, physiological, or insulin-like growth factor 1 receptor-phosphoinositide 3-kinase-induced cardiac hypertrophy

Ribosomal S6 kinases (S6Ks) have been depicted as critical effectors downstream of growth factor pathways, which play an important role in the regulation of protein synthesis by phosphorylating the ribosomal protein, S6. The goal of this study was to determine whether S6Ks regulate heart size, are critical for the induction of cardiac hypertrophy in response to a pathological or physiological stimulus, and whether S6Ks are critical downstream effectors of the insulin-like growth factor 1 (IGF1)-phosphoinositide 3-kinase (PI3K) pathway. For this purpose, we generated and characterized cardiac-specific S6K1 and S6K2 transgenic mice and subjected S6K1(-/-), S6K2(-/-), and S6K1(-/-) S6K2(-/-) mice to a pathological stress (aortic banding) or a physiological stress (exercise training). To determine the genetic relationship between S6Ks and the IGF1-PI3K pathway, S6K transgenic and knockout mice were crossed with cardiac-specific transgenic mice overexpressing the IGF1 receptor (IGF1R) or PI3K mutants. Here we show that overexpression of S6K1 induced a modest degree of hypertrophy, whereas overexpression of S6K2 resulted in no obvious cardiac phenotype. Unexpectedly, deletion of S6K1 and S6K2 had no impact on the development of pathological, physiological, or IGF1R-PI3K-induced cardiac hypertrophy. These studies suggest that S6Ks alone are not essential for the development of cardiac hypertrophy.     

Mitochondrial impairment induced by poly(ADP-ribose) polymerase-1 activation in cortical neurons after oxygen and glucose deprivation

Neuronal cells injured by ischemia and reperfusion to a certain extent are committed to death in necrotic or apoptotic form. Necrosis is induced by gross ATP depletion or 'energy crisis' of the cell, whereas apoptosis is induced by a mechanism still to be defined in detail. Here, we investigated this mechanism by focusing on a DNA damage-sensor, poly(ADP-ribose) polymerase-1 (PARP-1). A 2-h oxygen and glucose deprivation (OGD) followed by reoxygenation (Reox) induced apoptosis, rather than necrosis, in rat cortical neurons. During the Reox, PARP-1 was much activated and autopoly(ADP-ribosyl)ated, consuming the substrate, NAD+. Induction of apoptosis by OGD/Reox was suppressed by overexpression of Bcl-2, indicating mitochondrial impairment in this induction process. Mitochondrial permeability transition (MPT), or membrane depolarization, and a release of proapoptotic proteins, i.e. cytochrome c, apoptosis-inducing factor and endonuclease G, from mitochondria were observed during the Reox. These apoptotic changes of mitochondria and the nucleus were attenuated by PARP-1 inhibitors, 1,5-dihydroxyisoquinoline and benzamide, and also by small interfering RNA specific for PARP-1. These results indicated that PARP-1 plays a principal role in inducing mitochondrial impairment that ultimately leads to apoptosis of neurons after cerebral ischemia.     

In vitro fertilization and subsequent development of porcine oocytes using cryopreserved and liquid-stored spermatozoa from various boars

We had previously developed a porcine IVF system using a chemically defined medium, i.e., porcine gamete medium supplemented with theophylline, adenosine, and cysteine (PGMtac). In the present study, we investigated the utility of this IVF system using different types of semen: (1) cryopreserved ejaculated (n = 8); (2) cryopreserved epididymal (n = 4); and (3) liquid-stored ejaculated (n = 5). Cryopreserved spermatozoa were prepared by three methods. In vitro-matured porcine oocytes were fertilized for 20 h in PGMtac using each type of semen, and the presumptive zygotes were cultured in porcine zygote medium (PZM)-4 for 5 days. In the case of frozen-thawed spermatozoa, the number of spermatozoa per penetrated oocyte (1.1-1.7), rate of blastocyst formation (26-56%), and total number of cells per blastocyst (34-49) differed (P < 0.05) among freezing methods. However, blastocysts were produced using all types of cryopreserved spermatozoa (14-75%). When spermatozoa were liquid-stored for 1-14 days after semen collection, the rate of sperm penetration (P < 0.05) decreased as storage time increased, although there was no significant reduction in sperm motility during storage. In all groups, semen that had been stored within 10 days after collection enabled blastocyst production in vitro (20-48%). In conclusion, this IVF system, which uses a chemically defined medium, had widespread utility with both frozen-thawed and liquid-stored spermatozoa.     

Active transport and accumulation of iodide by newly isolated marine bacteria

Iodide (I(-))-accumulating bacteria were isolated from marine sediment by an autoradiographic method with radioactive (125)I(-). When they were grown in a liquid medium containing 0.1 microM iodide, 79 to 89% of the iodide was removed from the medium, and a corresponding amount of iodide was detected in the cells. Phylogenetic analysis based on 16S rRNA gene sequences indicated that iodide-accumulating bacteria were closely related to Flexibacter aggregans NBRC15975 and Arenibacter troitsensis, members of the family Flavobacteriaceae. When one of the strains, strain C-21, was cultured with 0.1 microM iodide, the maximum iodide content and the maximum concentration factor for iodide were 220 +/- 3.6 (mean +/- standard deviation) pmol of iodide per mg of dry cells and 5.5 x 10(3), respectively. In the presence of much higher concentrations of iodide (1 microM to 1 mM), increased iodide content but decreased concentration factor for iodide were observed. An iodide transport assay was carried out to monitor the uptake and accumulation of iodide in washed cell suspensions of iodide-accumulating bacteria. The uptake of iodide was observed only in the presence of glucose and showed substrate saturation kinetics, with an apparent affinity constant for transport and a maximum velocity of 0.073 muM and 0.55 pmol min(-1) mg of dry cells(-1), respectively. The other dominant species of iodine in terrestrial and marine environments, iodate (IO(3)(-)), was not transported.     

Water extract of the root of Lindera strychnifolia slows down the progression of diabetic nephropathy in db/db mice

We examined a possible preventive effect of Linderae radix (LR), the root of Lindera strychnifolia, on the progression of diabetic nephropathy. Water extract of Linderae radix (LR extract) was orally administered to the C57BL/KsJ-db/db (db/db) mice, a model of genetic diabetes, at a dose of 730 mg/kg/day for 12 week. The LR extract treatment did not affect glucose metabolism and systolic pressure. However, it resulted in a better renal function as evaluated by creatinine clearance (Ccr) and serum creatinine than the control; Ccr and serum creatinine were progressively worsened in controls (0.13+/-0.01 (l/day) and 0.69+/-0.04 (mg/dl), respectively) whereas unchanged in the treated group (0.24+/-0.03 (l/day), p<0.05 and 0.53+/-0.04 (mg/dl), p<0.05, respectively). Kidneys of the LR extract-treated group showed glomeruli with greater area and cell population, smaller glomerular sclerotic index, and less fibrosis in glomeruli, where apoptotic rate of glomerular cells were decreased compared with the control kidneys. Furthermore, renal TGF-beta(1) expression was decreased in the LR extract-treated group. These findings suggest that the LR therapy can be a novel therapeutic approach against diabetic nephropathy.     

Nonthermal killing effect of microwave irradiation

Summary Suspensions of E. coli were exposed to microwave irradiation at constant temperatures. No cell death was observed at 35°C, whereas, at 45, 47, and 50°C, the death rates of E. coli exposed to microwave irradiation were higher than those obtained in conventional heat sterilization at the same temperatures.