Prolonged effect of fluid flow stress on the proliferative activity of mesothelial cells after abrupt discontinuation of fluid streaming

Encapsulating peritoneal sclerosis (EPS) often develops after transfer to hemodialysis and transplantation. Both termination of peritoneal dialysis (PD) and transplantation-related factors are risks implicated in post-PD development of EPS, but the precise mechanism of this late-onset peritoneal fibrosis remains to be elucidated. We previously demonstrated that fluid flow stress induced mesothelial proliferation and epithelial-mesenchymal transition via mitogen-activated protein kinase (MAPK) signaling. Therefore, we speculated that the prolonged bioactive effect of fluid flow stress may affect mesothelial cell kinetics after cessation of fluid streaming. To investigate how long mesothelial cells stay under the bioactive effect brought on by fluid flow stress after removal of the stress, we initially cultured mesothelial cells under fluid flow stress and then cultured the cells under static conditions. Mesothelial cells exposed to fluid flow stress for a certain time showed significantly high proliferative activity compared with static conditions after stoppage of fluid streaming. The expression levels of protein phosphatase 2A, which dephosphorylates MAPK, in mesothelial cells changed with time and showed a biphasic pattern that was dependent on the duration of exposure to fluid flow stress. There were no differences in the fluid flow stress-related bioactive effects on mesothelial cells once a certain time had passed. The present findings show that fluid flow stress exerts a prolonged bioactive effect on mesothelial cells after termination of fluid streaming. These findings support the hypothesis that a history of PD for a certain period could serve as a trigger of EPS after stoppage of PD.     

Drug Resistance of Enteric Bacteria XIII. Distribution of R Factors in Escherichia coli Strains Isolated from Livestock

Escherichia coli strains isolated from 151 swine and 108 fowl, which were kept at the Animal Health Center, Maebashi, Japan, were surveyed for drug resistance and distribution of R factors. All of the swine and 38% of the fowl excreted E. coli strains resistant to tetracycline, chloramphenicol, streptomycin, and sulfanilamide, or certain combinations thereof. Among 278 resistant cultures isolated from swine, 13% were found to be resistant to one antibiotic, whereas 87% were resistant to more than one antibiotic. Among these resistant strains, 40% carried R factors which were transferable by the usual conjugal process. The resistance patterns of these R factors included 36% which were singly resistant and 64% which were multiply resistant. Among 54 resistant cultures isolated from fowl, 24% were singly resistant and 76% were multiply resistant. Of the resistant strains from fowl, 22% carried R factors. The resistance patterns of R factors included 50% of the singly resistant type and 50% which were multiply resistant. In spite of feeding with dairy products containing only tetracycline, a high incidence of multiple resistance was observed in the E. coli strains and the R factors isolated from these animals.     

Endothelin stimulates c-fos and c-myc expression and proliferation of vascular smooth muscle cells

Recently, a potent vasoconstrictor peptide, endothelin (EDT), was isolated from vascular endothelial cells. We examined its effect on rat vascular smooth muscle cells (VSMCs). EDT induced the elevation of intracellular calcium, which was dependent on extracellular calcium and inhibited by a calcium-channel antagonist in a competitive manner. EDT caused a rapid and transient increase in the c-fos and c-myc mRNA levels and stimulated the DNA synthesis of VSMCs in a dose-dependent manner. This effect of EDT on the proliferation of VSMCs might be related to the development of atherosclerosis.     

Alteration of redox state of human serum albumin in patients under anesthesia and invasive surgery

Human serum albumin is a mixture of mercapt- (HMA, reduced form) and nonmercaptalbumin (HNA, oxidized form). We studied the mercapt↔nonmercapt conversion of human serum albumin, which reflects the redox state of the extracellular fluids, in cardiac and other common surgical patients using high-performance liquid chromatography. Mean values of [(HMA)/(HMA + HNA)] ± standard deviation [f_HMA ± σ], for patients who received common surgery (group 1) and cardiac surgery (group 2) at the start of anesthesia were0.636±0.50(n=83) and 0.615±0.062(n=14), respectively. f_HMA values were markedly lower than those for healthy male adults of 0.750±0.028(n=28). f_HMA values increased at 24 h after the start of anesthesia and decreased on the 4th postoperative day in most of the patients. These postoperative changes were prominent in surgical cardiac patients. Although f_HMA values after the 7th postoperative day recovered to those at the start of anesthesia in almost all of common surgical patients, those in cardiac surgical patients, never recovered even on the 21st postoperative day.     

IN VITRO FERTILIZATION OF IN VITRO MATURED MINKE WHALE (BALAENOPTERA ACUTOROSTRATA) FOLLICULAR OOCYTES

In vitro fertilization of follicular oocytes harvested from ovaries and matured in vitro was attempted for 55 minke whales ( Balaenoptera acutorostrata ) captured for Japanese research purposes in the Antarctic Ocean during the period from November 1995 to March 1996. In Experiment 1, effects of culture duration (96 h or 120 h) on maturation of follicular oocytes and addition of caffeine (5 mM) and/or heparin (100 pg/ml) on sperm penetration and pro-nuclear formation were investigated. Spermatozoa recovered from the vasa deferentia of four mature males were diluted (5-fold) and frozen at - 80°C. The post-thawed and pooled spermatozoa were used for in vitro insemination. A higher ( P < 0.05) proportion of the oocytes cultured for 120 h (34.2% of 260) progressed beyond the second metaphase stage than of the oocytes cultured for 96 h (26.0% of 262). For the matured oocytes, higher rates of penetration ( P < 0.05) and pronuclear formation ( P < 0.01) were obtained in the oocytes cultured for 120 h (55.1% and 40.4%) than in those cultured for 96 h (32.4 % and 20.6%). Addition of caffeine and heparin did not show a significant effect. In Experiment 2, follicular oocytes matured for 120 h and then inseminated were cultured to examine the subsequent development in two culture systems (with and without co-cultured cumulus cells). Of 448 inseminated oocytes, cleaved embryos (2–16 cells) were observed with (5.8%) and without (4.9%) co-cultured systems. No cleavage was observed in 54 ova without insemination. These results indicate that in vitro fertilization of minke whale in vitro matured follicular oocytes with cryopreserved spermatozoa is possible, yielding cleaved embryos.     

Shell productivity of the large benthic foraminifer Baculogypsina sphaerulata,based on the population dynamics in a tropical reef environment

Carbonate production by large benthic foraminifers is sometimes comparable to that of corals and coralline algae, and contributes to sedimentation on reef islands and beaches in the tropical Pacific. Population dynamic data, such as population density and size structure (size-frequency distribution), are vital for an accurate estimation of shell production of foraminifers. However, previous production estimates in tropical environments were based on a limited sampling period with no consideration of seasonality. In addition, no comparisons were made of various estimation methods to determine more accurate estimates. Here we present the annual gross shell production rate of Baculogypsina sphaerulata, estimated based on population dynamics studied over a 2-yr period on an ocean reef flat of Funafuti Atoll (Tuvalu, tropical South Pacific). The population density of B. sphaerulata increased from January to March, when northwest winds predominated and the study site was on the leeward side of reef islands, compared to other seasons when southeast trade winds predominated and the study site was on the windward side. This result suggested that wind-driven flows controlled the population density at the study site. The B. sphaerulata population had a relatively stationary size-frequency distribution throughout the study period, indicating no definite intensive reproductive period in the tropical population. Four methods were applied to estimate the annual gross shell production rates of B. sphaerulata. The production rates estimated by three of the four methods (using monthly biomass, life tables and growth increment rates) were in the order of hundreds of g CaCO₃ m⁻² yr⁻¹ or cm⁻³ m⁻² yr⁻¹, and the simple method using turnover rates overestimated the values. This study suggests that seasonal surveys should be undertaken of population density and size structure as these can produce more accurate estimates of shell productivity of large benthic foraminifers.

     

Late Pleistocene origin of the entire circumarctic range of the arctic‐alpine plant Kalmia procumbens

The circumarctic ranges of arctic‐alpine plants are thought to have been established in the late Pliocene/early Pleistocene, when the modern arctic tundra was formed in response to climate cooling. Previous findings of range‐wide genetic structure in arctic‐alpine plants have been thought to support this hypothesis, but few studies have explicitly addressed the temporal framework of the genetic structure. Here, we estimated the demographic history of the genetic structure in the circumarctic Kalmia procumbens using sequences of multiple nuclear loci and examined whether its genetic structure reflects prolonged isolation throughout the Pleistocene. Both Bayesian clustering and phylogenetic analyses revealed genetic distinction between alpine and arctic regions, whereas detailed groupings were somewhat discordant between the analyses. By assuming a population grouping based on the phylogenetic analyses, which likely reflects a deeper intraspecific divergence, we conducted model‐based analyses and demonstrated that the intraspecific genetic divergence in K. procumbens likely originated during the last glacial period. Thus, there is no need to postulate range separation throughout the Pleistocene to explain the current genetic structure in this species. This study demonstrates that range‐wide genetic structure in arctic‐alpine plants does not necessarily result from the late Pliocene/early Pleistocene origin of their circumarctic ranges and emphasizes the importance of a temporal framework of the current genetic structure for understanding the biogeographic history of the arctic flora.     

Yeast thioredoxin-enriched extracts for mitigating the allergenicity of foods

Thioredoxin (TRX) catalyzes the reduction of disulfide bonds in proteins via the NADPH-dependent thioredoxin reductase system. Reducing the disulfide bonds of allergenic proteins in food by TRX lowers the allergenicity. We established in this study a method to prepare TRX-enriched extracts from the edible yeast, Saccharomyces cerevisiae, on a large and practical scale, with the objective of developing TRX-containing functional foods to mitigate food allergy. Treating with the yeast TRX-enriched extracts together with NADPH and yeast thioredoxin reductase enhanced the pepsin cleavage of β-lactoglobulin and ovomucoid (OM). We also examined whether yeast TRX can mitigate the allergenicity of OM by conducting immediate allergy tests on guinea pigs. The treatment with TRX reduced the anaphylactic symptoms induced by OM in these tests. These results indicate that yeast TRX was beneficial against food allergy, raising the possibility that yeast TRX-enriched extracts can be applied to food materials for mitigating food allergy.     

Enzymatic synthesis of a novel cyclic pentasaccharide consisting of alpha-D-glucopyranose with 6-alpha-glucosyltransferase and 3-alpha-isomaltosyltransferase

A novel cyclic pentasaccharide (CPS) and a branched cyclic pentasaccharide (6G-CPS) consisting of d-glucopyranose were synthesized with 6-alpha-glucosyltransferase (6GT) and 3-alpha-isomaltosyltransferase (IMT) from Bacillus globisporus N75. The structure of CPS was cyclo-[-->6)-alpha-D-Glcp-(1-->3)-alpha-D-Glcp-(1-->6)-alpha-D-Glcp-(1-->3)-alpha-D-Glcp-(1-->4)-alpha-D-Glcp-(1-->]. The other, 6G-CPS, had the structure cyclo-[-->6)-alpha-D-Glcp-(1-->3)-alpha-D-Glcp-(1-->6)-alpha-D-Glcp-(1-->3)-[alpha-D-Glcp-(1-->6)]-alpha-D-Glcp-(1-->4)-alpha-D-Glcp-(1-->]. The formation of CPS was presumed to occur after the following four successive reactions: a 6-glucosyltransfer reaction with 6GT, a 4-glucosyltransfer reaction with 6GT, a 3-isomaltosyltransfer reaction with IMT, and a cyclization reaction with IMT.     

Regulation of capacitative Ca2+ entry by prothoracicotropic hormone in the prothoracic glands of the silkworm, Bombyx mori

Measurements of Ca2+ influx in Fura-2/AM loaded steroidogenic cells (prothoracic glands; PGs) of the silkworm, Bombyx mori showed that application of the neuropeptide prothoracicotropic hormone (PTTH) can increase the intracellular [Ca2+]i. This PTTH-mediated Ca2+ influx in PG cells had kinetic patterns and pharmacological characteristics similar to those induced by thapsigargin. Namely, it produced increases in intracellular Ca2+ levels only in the presence of extracellular Ca2+, it was blocked by Gd3+ and 2-Aminoethoxydiphenylborate (2-APB), and it was unaffected by several toxins or compounds that block voltage-activated Ca2+ channels. Moreover, the PTTH-stimulated increase of Ca2+ levels was eliminated in the presence of heparin (an IP3 receptor blocker), and by TMB-8 which also blocked any PTTH-dependent increase of ecdysteroid secretion. The PTTH-mediated increase of Ca2+ levels was not affected by the non-hydrolysable GDP analogue, GDPbetaS, an indication that a G protein is not downstream of the PTTH receptor. These results argue strongly in favor of gating by the PTTH receptor of capacitative Ca2+ entry (CCE) channels (or store-operated Ca2+ channels (SOCs)) by a mechanism that does not involve any G proteins but requires the presence of functional IP3 receptors. Because the ability of PTTH to stimulate the [Ca2+]i levels of PG cells was completely mimicked by thapsigargin and exhibited a pharmacological profile similar to CCE mechanisms, we believe that PTTH directly regulates a CCE pathway in PG cells thereby activating a plethora of downstream regulators responsible for ecdysteroid secretion by the PGs of Bombyx mori.