Carbamoyl-PROXYL-enhanced MRI detects very small disruptions in brain vascular permeability induced by dietary cholesterol

Background

Gd-DTPA-enhanced magnetic resonance imaging (MRI) is a conventional method for non-invasive investigation of blood-brain-barrier (BBB) permeability in animal models. It allows the visualization of serious injury to the BBB. We developed a novel approach for detecting very small disruptions in BBB permeability induced by dietary cholesterol by using carbamoyl-PROXYL (CMP) as an MRI contrast probe.

Methods

Mice were separated into two groups: normal diet (ND-mice) and high cholesterol diet (CD-mice). MRI-signal dynamics, plasma cholesterol, matrix metalloproteinase (MMP-9, MMP-2), and the white blood cell profile were analyzed. For the MRI analysis, two regions-of-interest (ROI) were selected: brain (ROI-1) and surrounding area (ROI-2).

Results

In the ROI-2 of ND-mice, CMP- or Gd-enhanced MRI-signal followed typical kinetics with a half-life of signal decay (τ_1/2) ~ 8 or ~ 15 min, respectively. In CD-mice, the MRI-signal increased continuously without decay.In the ROI-1 of ND- and CD-mice, MRI-signal enhancement was not detected by Gd-DTPA. In the ROI-1 of ND-mice, CMP-induced MRI-signal enhancement was negligible, while in CD-mice, it was significant (τ_1/2 > 15 min).Hypercholesterolemia increased the plasma levels of MMP-9 and neutrophils.

Conclusions

Hypercholesterolemia increases vascular permeability, which is mediated by MMP-9 and neutrophils.

General significance

Even very small disruptions in brain vascular permeability could be detected by CMP-enhanced MRI but not by Gd-DTPA-enhanced MRI.     

Phylogenetic relationships within Echinococcus and Taenia tapeworms (Cestoda: Taeniidae): an inference from nuclear protein-coding genes

The family Taeniidae of tapeworms is composed of two genera, Echinococcus and Taenia, which obligately parasitize mammals including humans. Inferring phylogeny via molecular markers is the only way to trace back their evolutionary histories. However, molecular dating approaches are lacking so far. Here we established new markers from nuclear protein-coding genes for RNA polymerase II second largest subunit (rpb2), phosphoenolpyruvate carboxykinase (pepck) and DNA polymerase delta (pold). Bayesian inference and maximum likelihood analyses of the concatenated gene sequences allowed us to reconstruct phylogenetic trees for taeniid parasites. The tree topologies clearly demonstrated that Taenia is paraphyletic and that the clade of Echinococcus oligarthrus and Echinococcusvogeli is sister to all other members of Echinococcus. Both species are endemic in Central and South America, and their definitive hosts originated from carnivores that immigrated from North America after the formation of the Panamanian land bridge about 3 million years ago (Ma). A time-calibrated phylogeny was estimated by a Bayesian relaxed-clock method based on the assumption that the most recent common ancestor of E. oligarthrus and E. vogeli existed during the late Pliocene (3.0 Ma). The results suggest that a clade of Taenia including human-pathogenic species diversified primarily in the late Miocene (11.2 Ma), whereas Echinococcus started to diversify later, in the end of the Miocene (5.8 Ma). Close genetic relationships among the members of Echinococcus imply that the genus is a young group in which speciation and global radiation occurred rapidly.     

Immunochemical examinations of cytochrome P-450 in various tissues of human fetuses using antibodies to human fetal cytochrome P-450, P-450 HFLa

P-450 HFLa is a form of cytochrome P-450 purified from human fetal livers. The amounts of P-450 HFLa in several fetal tissues were determined immunochemically. Detectable amounts presented in livers, kidneys, adrenals, lungs and some other tissues of human fetuses. The amounts were the highest in livers. Activities of 7-ethoxycoumarin O-deethylase and benzo(a)pyrene hydroxylase in livers but not in adrenals were inhibited by the anti-P-450 HFLa antibodies, probably suggesting that distinct forms of cytochrome P-450 are responsible for the oxidations in livers and adrenals.     

Genetic Control of Meiosis in Rice, ORYZA SATIVA L. III. Effect of DS Genes on Genetic Recombination

The recombination frequency as influenced by five independent recessive ds genes was measured on three segments of different chromosomes of rice, Oryza sativa L. Each ds gene in the homozygous condition resulted in an almost equally reduced recombination frequency in the three segments. When the mean reduction in recombination frequency was related to the reduction of chiasma frequency, the five ds genes were divided into two types: in one type the reduction of chiasma frequency almost corresponded to the mean reduction of recombination frequency, and in the other the chiasma frequency was greatly reduced in comparison with the mean reduction of recombination frequency. Three of the five ds genes were found to belong to the former group. In both types, normal synaptonemal complexes were observed in pachytene cells homozygous for ds genes. This finding suggests that ds genes do not affect the formation of synaptonemal complexes which are regarded as the prerequisite structure for crossing over.     

Isolation of a neuropeptide corresponding to the N-terminal 27 residues of the pituitary adenylate cyclase activating polypeptide with 38 residues (PACAP38)

A novel neuropeptide with 38 residues (PACAP38) was isolated from ovine hypothalamic tissues using the pituitary adenylate cyclase activation in rat pituitary cell cultures as a parameter of the biological activity (Miyata et al, Biochem. Biophys. Res. Commun. 164, 567-574, 1989). From the side fractions obtained during the purification of PACAP38, a shorter form peptide with 27 residues corresponding to the N-terminal 27 amino acids of PACAP38 and amidated C-terminus was isolated and named as PACAP27. Synthetic PACAP27 showed a biological activity of adenylate cyclase stimulation comparable to PACAP38. Moreover PACAP27 which shows a considerable homology with vasoactive intestinal polypeptide (VIP) demonstrated a similar vasodepressor activity as VIP, but the adenylate cyclase stimulating activity was about 1000 times greater than VIP.     

Correction to: Comparative analysis of sperm motility in liquid and seminal coagulum portions between Bornean orangutan (Pongo pygmaeus) and chimpanzee (Pan troglodytes)

Primates - In the original publication of the article, the coauthor “Takashi Hayakawa” was wrongly assigned as co-corresponding author.     

Purification of cytochrome P-450 from polychlorinated biphenyl-treated crab-eating monkeys: high homology to a form of human cytochrome P-450

Cytochrome P-450, designated as P-450-MK2, was purified to an electrophoretic homogeneity from polychlorinated biphenyl (PCB)-treated female crab-eating monkeys. P-450-MK2 catalyzed nifedipine and nilvadipine oxidations, at a rate comparable to human P-450-HM1. The N-terminal amino acid sequence of P-450-MK2 was highly homologous to those of P-450-HM1 and NF 25. The antibodies to P-450-HM1 recognized P-450-MK2 and effectively inhibited the activity of testosterone 6 beta-hydroxylase in monkey liver microsomes. These results suggest that a form of cytochrome P-450 corresponding to human P-450-HM1 or P-450NF which belongs to the P450 III gene family is also present in liver microsomes of crab-eating monkeys.     

A quantitative study of dual action of nickel ions on the taste response to calcium ions of single fibers of the frog glossopharyngeal nerve: inhibition and enhancement by nickel ions

Unitary discharges from single water fibers of the frog glossopharyngealnerve, caused by stimulation with 0.02–5 mM CaSO₄, wererecorded from fungiform papillae with a suction electrode. NiSO₄at concentrations of 0.2–2 mM, namely, at concentrationsthat are barely effective in producing impulses, had a dualaction on the Ca²⁺ response: NiSO₄ caused both inhibition andenhancement of the Ca²⁺ response. In the present study, thisdual action of Ni²⁺ ions on the Ca²⁺ response was investigatedin detail. Single water fibers yielded a saturation type ofconcentration-response curve for CaSO₄, which suggested thatsulfateions do not affect the Ca²⁺ response. Thus, sulfateswere used as test salts in the present study. At low concentrationsof Ca²⁺ ions, Ni²⁺ ions inhibited the Ca²⁺ response, but athigher concentrations of Co²⁺ ions they enhanced it. The resultscan be explained quantitatively by the hypothesis that Ni²⁺ions inhibit the Ca²⁺ response by competing with Ca²⁺ ions forthe Ca²⁺ receptor (X_ca) that is responsible for the Ca²⁺ responseand that Ni²⁺ ions enhance the Ca²⁺ response by acting on amembrane element that interacts with X_ca. Double-reciprocalplots of the data indicate that the enhancing action of Ni²⁺ions is saturated at 1–2 mM Ni²⁺ ions and that Ni²⁺ ionsat these concentrations increase the maximal response of theCa²⁺ response by 182%. Dissociation constants for the Ca-X_cacomplex and the Ni-X_ca, complex were 4.2 x 10^–5 M and7.6 x 10^–5 M, respectively. The analysis suggests thatNi²⁺ ions enhance the Ca²⁺ response by affecting the Ca-X_cacomplex without altering the affinity of X_ca, for Ca²⁺ ions.