Transport of p-aminohippuric acid,uric acid and glucose in highly purified rabbit renal brush border membranes

A procedure for preparing highly purified brush border membranes from rabbit kidney cortex using differential and density gradient centrifugation is described. Brush border membranes prepared by this procedure were substantially free of basal-lateral membranes, mitochondria, endoplasmic reticulum and nuclear material as evidenced by an enrichment factor of less than 0.3 for (Na⁺ + K⁺)-ATPase, succinate dehydrogenase, NADPH-cytochrome c reductase and DNA. Alkaline phosphatase was enriched ten fold indicating that the membranes were enriched at least 30 fold with respect to other cellular organelles. The yield of brush border membranes was 20%.Transport of d-glucose by the membranes was identical to that previously reported except that the Arrhenius plot for temperature dependence of transport was curvilinear (E_A = 11.3–37.6 kcal/mol) rather than biphasic. Transport of p-aminohippuric acid and uric acid were increased by the presence of NaCl, either gradient or preequilibrated. However, no overshoot was obtained in the presence of a NaCl gradient, and KCl and LiCl also produced equivalent stimulation of transport suggesting a nonspecific ionic strength effect. Uptakes of p-aminohippuric acid and uric acid were not saturable, and were increased markedly by reducing the pH from 7.5 to 5.6. Probenecid (1 mM) reduced p-aminohippuric acid and uric acid (50 μM) uptake by 49% and 21%, respectively. We conclude that the uptake of uric acid and p-aminohippuric acid by renal brush border membranes of the rabbit occurs primarily by a simple solubility-diffusion mechanism.     

An analogous ligand of blue copper active sites : synthesis, electron spin resonance characteristics of its copper(II) complex, and role of proline residue.

In order to clarify a role of the proline residue at near cysteine and histidine positions of plastocyanin and azurin, N-mercaptoacetylglycyl-L-prolyl-L-histidine has been synthesized as an analogous ligand of blue copper sites and the spectroscopic properties of its Cu(II) complex compared with those of the N-mercaptoacetylglycylglycyl-L-histidine-Cu(II) complex. In the present tetrapeptide-Cu(II) complexes, the exchange of the glycine of the third position by the proline residue effects a red shift(80 nm) of the visible absorption and a decrease (192→75×10^?4cm^?1) of the copper hyperfine splitting. The introduction of proline residue induces a change of the complex geometry from D_4h to T_d symmetries.     

Capturing human trophoblast development with naive pluripotent stem cells in vitro

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Mutagenicity of ptaquiloside, the carcinogen in bracken, and its related illudane-type sesquiterpenes. I. Mutagenicity in Salmonella typhimurium

Ptaquiloside, a potent carcinogen of an illudane-type sesquiterpene glycoside isolated from Pteridium aquilium, and its related compounds, hypolosides having the same nucleus isolated from the Pteridaceae, exhited marked mutagenicity in the modified Ames test with Salmonella typhimurian TA98 and A100 using a preincubation at pH 8.5 Illudins M and S, sesquiterpenes of the same illudane type from basidiomycetes, also exhibited mutagenicity. The structural requirements for mutagenicity are discussed.     

Isolation and transposon mutagenesis of a Pseudomonas putida KT2442 toluene-resistant variant: involvement of an efflux system in solvent resistance

A toluene-resistant variant of Pseudomonas putida KT2442, strain TOL, was isolated after liquid cultivation under xylene followed by toluene for 1 month in each condition. Almost all the populations of the variant strain formed small but readily visible colonies under toluene within 24 h at 30°C. The toluene-resistant strain also showed an increase in resistance to some unrelated antibiotics. Several toluene-sensitive Tn5 mutants have been isolated from the toluene-resistant strain and showed various levels of sensitivity. Most of these mutations did not cause significant changes in antibiotic resistance; however, one of the mutants (TOL-4) was highly susceptible to both organic solvents and various antibiotics, especially β-lactams. Sequencing analysis revealed that the mutation in TOL-4 had been introduced into a gene that may encode a transporter protein of an efflux system. This efflux system is very similar to one of the multidrug efflux systems of Pseudomonas aeruginosa. These observations indicate that a multidrug efflux system plays a major role in the organic solvent resistance of P. putida TOL. However, several other genes may also be involved. Received: December 18, 1997 / Accepted: March 16, 1998     

Mutagenic reactivities of 3,4-dinitrobiphenyl derivatives

3,4-Dinitrobiphenyl derivatives were mutagenic in Salmonella typhimurium TA98, TA98/1,8-DNP6 and in TA98NR. We describe here the specific reactivity of 3,4-dinitrobiphenyl derivatives with diluted sodium hydroxide solution and the determination of the amounts of released nitrous ion. 3,4-Dinitrobiphenyl derivatives begin to release nitrous ions when treated with NaOH solution at a concentration of 10(-3) N. The behavior of 4NQO and o-dinitrobenzene was the same as that of 3,4-dinitrobiphenyl derivatives. The residues of 3,4-dinitrobiphenyl derivatives, after releasing nitrous ions, were estimated to be hydroxy-nitrobiphenyls, as by GC/MS, we found the formation of o-nitrophenol in the reaction mixture of o-dinitrobenzene with aqueous NaOH solution. 3,4,4'-Trinitrobiphenyl, 3,4,3',4'-tetranitrobiphenyl and 4NQO had reduced mutagenic potency in Salmonella typhimurium TA98 following treatment with diluted NaOH. In order to elucidate the ultimate forms of 3,4-dinitrobiphenyl derivatives, we investigated the reaction of o-dinitrobenzene as a basic model substance of 3,4-dinitrobiphenyl, with nucleic bases in the presence of NaOH in nonaqueous solvent. o-Nitrophenyl guanine and adenine adducts were obtained.     

Serum haptoglobin type and liver cirrhosis.

Haptoglobin phenotypes were studied by a polyacrylamide gel electrophoresis on 200 blood donors and 105 patients with liver cirrhosis, of which 79% belonged to non-alcoholic etiology. Though no difference of haptoglobin types could be found between blood donors with positive and negative hepatitis B antigen, the cirrhois patients had an excess haptoglobin gene 1. The patients with haptoglobin gene 1 were associated with severe liver dysfunction. Since the family pedigrees of the patients with type 1--1 excluded individuals with type 2--2, the phenotypes seemed to be stable in the cirrhotic process. The possibility that the haptoglobin 2 gene offered resistence to the non-alcoholic cirrhosis was discussed.     

Relationship between plasma asymmetric dimethylarginine and nitric oxide levels affects aerobic exercise training-induced reduction of arterial stiffness in middle-aged and older adults

[Purpose]Aerobic exercise training (AT) reverses aging-induced deterioration of arterial stiffness via increased arterial nitric oxide (NO) production. Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NO synthase, was decreased by AT. However, whether AT-induced changes in ADMA levels are related to changes in nitrite/nitrate (NOx) levels remains unclear. Accordingly, we aimed to clarify whether the relationship between plasma ADMA and NOx levels affected the AT-induced reduction of arterial stiffness in middle-aged and older adults.[Methods]Thirty-one healthy middle-aged and older male and female subjects (66.4 ± 1.3 years) were randomly divided into two groups: exercise intervention and sedentary controls. Subjects in the training group completed an 8-week AT (60%–70% peak oxygen uptake [V˙O2peak] for 45 min, 3 days/week).[Results]AT significantly increased V˙O2peak (p < 0.05) and decreased carotid β-stiffness (p < 0.01). Moreover, plasma ADMA levels were significantly decreased while plasma NOx levels and NOx/ADMA ratio were significantly increased by AT (p < 0.01). Additionally, no sex differences in AT-induced changes of circulating ADMA and NOx levels, NOx/ADMA ratio, and carotid β-stiffness were observed. Furthermore, the AT-induced increase in circulating ADMA levels was negatively correlated with an increase in circulating NOx levels (r = -0.414, p < 0.05), and the AT-induced increase in NOx/ADMA ratio was negatively correlated with a decrease in carotid β-stiffness (r = -0.514, p < 0.01).[Conclusion]These results suggest that the increase in circulating NOx with reduction of ADMA elicited by AT is associated with a decrease in arterial stiffness regardless of sex in middle-aged and older adults.     

Transfer of <Emphasis Type="Italic">Asterosporium orientale</Emphasis> to the genus <Emphasis Type="Italic">Prosthemium</Emphasis> (Pleosporales,Ascomycota): a common coelomycetous fungus with stellate conidia occurring on twigs of <Emphasis Type="Italic">Betula</Emphasis> spp.

Asterosporium orientale, described on Betula ermanii, is transferred to the genus Prosthemium, and a new combination, P. orientale, is proposed. Because of the morphological similarities, P. asterosporum originally described from twigs of B. pendula is considered as a synonym of P. orientale.