Time of day improves efficacy and reduces adverse reactions of vitamin D3 in 5/6 nephrectomized rat

Time-dependent differences in adverse reactions and efficacy by a repeated administration of 1,25(OH)2 vitamin D3 (vit D, 0.3 microg/Kg/day for 12 weeks) were examined in 5/6 nephrectomized rats under a condition of 12-hour light-dark cycle. The 5/6 nephrectomy increased serum concentrations of phosphate, osteocalcin and PTH, and urinary excretions of phosphate and deoxypyridinoline (DPD) while the maneuver reduced serum Ca concentration and its urinary excretion. Animals with a dosing of the drug at 2 hours after light on (HALO) had more grade of hypercalcemia and hyperphosphatemia than those at 14 HALO. Reduction of serum intact PTH and increase of serum vit D were observed in both groups with a similar extent. Increase of osteocalcin by the drug was greater in 14 HALO trial. Urinary excretion of DPD was not influenced by the treatment. The increase in bone density of femur was greater in 14 HALO than in 2 HALO trials. These results suggest that adverse reactions of vit D were ameliorated and its efficacy was enhanced after the repeated dosing of the drug at 14 HALO. Time-dependent variation in the sensitivity of the drug to osteoblast was involved in the mechanism of these events, while the roles of pharmacokinetic alteration and renal response were small, if any.     

Evolution of Human Polyomavirus JC: Implications for the Population History of Humans

The polyomavirus JC virus (JCV), the etiological agent of progressive multifocal leukoencephalopathy, is ubiquitous in the human population, infecting children asymptomatically, then persisting in the kidney. The main mode of transmission of JCV is from parents to children through long-term cohabitation. Twelve JCV subtypes that occupy unique domains in Europe, Africa, and Asia have been identified. Here, we attempted to elucidate the evolutionary relationships among JCV strains worldwide using the whole-genome approach with which a highly reliable phylogeny of JCV strains can be reconstructed. Sixty-five complete JCV DNA sequences, derived from various geographical regions and belonging to 11 of the 12 known subtypes, were subjected to phylogenetic analysis using three independent methods: the neighbor-joining, maximum parsimony, and maximum likelihood methods. The trees obtained with these methods consistently indicated that ancestral JCVs were divided into three superclusters, designated as Types A, B, and C. A split in Type A generated two subtypes, EU-a and -b, mainly containing European and Mediterranean strains. The first split in Type B generated Af2 (the major African subtype). Subsequent splits in Type B generated B1-c (a minor European subtype) and all seven Asian subtypes (B1-a, -b, -d, B2, MY, CY, and SC). Type C generated a single subtype (Af1), consisting of strains derived from western Africa. While the present findings provided a basis on which to classify JCV into types or subtypes, they have several implications for the divergence and migration of human populations. Received: 4 April 2001 / Accepted: 31 July 2001     

Development and evaluation of an enzyme-linked immunosorbent assay with recombinant SAG2 for diagnosis of Toxoplasma gondii infection in cats

Cats are pivotal in the transmission of Toxoplasma gondii. To develop a sensitive and specific serodiagnostic method for feline toxoplasmosis, surface antigen 2 (SAG2) of T. gondii was expressed in Escherichia coli and its diagnostic potential evaluated in an enzyme-linked immunosorbent assay (ELISA). The ELISA with recombinant SAG2 (rSAG2) was able to differentiate very clearly between sera from cats experimentally infected with T. gondii and sera from normal cats. Serum samples collected from domestic cats in Japan were investigated by the ELISA, and the results were compared with those of a commercially available latex agglutination test (LAT) kit. Of the 192 samples screened, 42 (21.9%) were positive by ELISA. Among the 42 ELISA-positive samples, 39 were positive by LAT. There was a significant correlation between ELISA and LAT titers. All the 150 ELISA-negative samples were negative by LAT. These results indicate that the ELISA with rSAG2 expressed in E. coli should be a useful method for detection of T. gondii infection in cats.     

Identification of a toxic mechanism of the plasticizers,phtahlic acid esters,which are putative endocrine disrupters: time-dependent increase in quinolinic acid and its metabolites in rats fed di(2-ethylhexyl)phthalate

We have reported that the administration of di(2-ethylhexyl)phthalate (DEHP) increased the formations of quinolinic acid (QA) and its lower metabolites on the tryptophan-niacin pathway. To discover the mechanism involved in disruption of the tryptophan-niacin pathway by DEHP, we assessed the daily urinary excretion of QA and its lower metabolites, and enzyme activities on the tryptophan-niacin pathway. Rats were fed with a niacin-free, 20% casein diet or the same diet supplemented with 0.1% DEHP or 0.043% phthalic acid and 0.067% 2-ethylhexanol added for 21 days. Feeding of DEHP increased the urinary excretions of QA and its lower metabolites in a time-dependent manner, and the increase of these excretions reached a peak at 11 days, but feeding of phthalic acid and 2-ethylhexanol had no effect. Feeding of DEHP, however, did not affect any enzyme activity including alpha-amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase (ACMSD), affecting the formation of QA, on the tryptophan-niacin pathway.     

Importance of permafrost as a source of water for plants in east Siberian taiga

Stable oxygen isotope ratios of plant water (sap water) were observed at Spasskaya Pad experimental forest near Yakutsk, Russia in 1997–1999. The ¹⁸O of sap water in larch trees (Larix gmelinii) decreased soon after leaf unfolding every year, indicating that snowmelt water was used in the beginning of summer. During mid to late summer, a clear difference in the water source used by plants was observed between wet summers and severe drought summers. The ¹⁸O values of water in larch trees were high (–17.8 to –16.1) in August 1999 (wet summer), but low (–20.4 to –19.7) in August 1998 (drought summer). These results indicated that plants used rainwater during a wet summer, but meltwater from permafrost was used by plants during a drought summer. One important role of permafrost is to provide a direct source of water for plants in a severe drought summer; another role is to keep surplus water in the soil until the next summer. If this permafrost system is disturbed by future global warming, unique monotypic stands of deciduous larch trees in east Siberia might be seriously damaged in a severe drought summer.     

Synthesis and testing of 2alpha-modified 1alpha,25-dihydroxyvitamin D(3) analogues with a double side chain: marked cell differentiation activity

The 2alpha-methyl-, 2alpha-(3-hydroxypropyl)-, and 2alpha-(3-hydroxypropoxy)-derivatives of the 'double side chain' analogue of 1alpha,25-dihydroxyvitamin D(3) were synthesized using Trost A-ring/CD-ring connective strategy. Regarding the requisite A-ring building blocks, a new, high yield and stereoselective route to the 2alpha-methyl compound starting from D-glucose was developed. All three new analogues showed potent HL-60 cancer cell differentiation activity.     

Development of 47 new microsatellite markers from a BTA6 library

Chromosome-specific libraries provide a means to isolate genetic markers from specific chromosomal regions. A small-insert BTA6 library, constructed by microdissection, was screened for dinucleotide repeats (CA)15 and (GA)15. A total of 47 new microsatellite loci were developed and tested for polymorphism and informativeness using the MARC bovine mapping family.     

Differential recognition of tyrosine-based basolateral signals by AP-1B subunit mu1B in polarized epithelial cells

To investigate the importance of tyrosine recognition by the AP-1B clathrin adaptor subunit mu1B for basolateral sorting of integral membrane proteins in polarized epithelial cells, we have produced and characterized a mutant form of mu1B. The mutant (M-mu1B) contains alanine substitutions of each of the four conserved residues, which in the AP-2 adaptor subunit micro2 are critical for interacting with tyrosine-based endocytosis signals. We show M-mu1B is defective for tyrosine binding in vitro, but is nevertheless incorporated into AP-1 complexes in transfected cells. Using LLC-PK1 cells expressing either wild type or M-mu1B, we find that there is inefficient basolateral expression of membrane proteins whose basolateral targeting signals share critical tyrosines with signals for endocytosis. In contrast, membrane proteins whose basolateral targeting signals are distinct from their endocytosis signals (transferrin and low-density lipoprotein receptors) accumulate at the basolateral domain normally, although in a manner that is strictly dependent on mu1B or M-mu1B expression. Our results suggest that mu1B interacts with different classes of basolateral targeting signals in distinct ways.     

Stable isotope and radiocarbon compositions of methane emitted from tropical rice paddies and swamps in Southern Thailand

Stable isotopes (¹³C, D) and radiocarbon weremeasured in methane bubbles emitted from rice paddies and swamps in southernThailand. Methane emitted from the Thai rice paddies was enriched in¹³C (mean ¹³C; –51.5 ±7.1 and–56.5 ± 4.6 for mineral soil and peat soil paddies,respectively)relative to the reported mean value of methane from temperate rice paddies(– 63 ± 5). Large seasonal variation was observed in¹³C(32) in the rice paddies, whereas variationinD was much more smaller (20), indicating that variation in¹³C is due mainly to changes in methane production pathways.Values of ¹³C were lower in swamps (–66.1 ±5.1)than in rice paddies. The calculated contribution of acetate fermentation from¹³C value was greater in rice paddies (mineral soils:62–81%, peat soils: 57–73%) than in swamps (27–42%). Din methane from Thai rice paddies (–324± 7 (n=46)) isrelativelyhigher than those from 14 stations in Japanese rice paddies ranging from–362 ± 5 (Mito: n=2) to –322 ± 8(Okinawa: n=3), due tohigher D in floodwaters. ¹⁴C content in methane produced fromThai rice paddies (127±1 pMC) show higher ¹⁴Cactivity compared with previous work in paddy fields and those from Thai swamps(110±2 pMC).