The Nemuro Belt is a tectonic belt in the Paleo‐Kuril Arc system, the NW Pacific region. The Paleo‐Kuril Arc has been interpreted as an intraoceanic arc system between the Izanagi and Pacific Plates ...during the Late Cretaceous, suggesting that the boundary between these plates was a trench. However, this study shows it was a volcanic arc that developed atop a continental margin. To determine the nature of this arc during the Late Cretaceous, U‐Pb ages of detrital zircons from the Nemuro and Urahoro Groups in the Paleo‐Kuril Arc were analyzed. Our results identify two distinct types of detrital zircon U‐Pb age distributions. The first (Type 1) is characterized by multimodal age distributions with peaks ranging from ca. 1.8 Ga to 78 Ma. The other (Type 2) exhibits a unimodal age distribution with a peak at 60‐52 Ma. These different age distributions indicate a provenance transition occurred between the Late Cretaceous and Paleogene. Precambrian zircons in Type 1 sandstones indicate that the Paleo‐Kuril Arc was part of a continental plate, presumably the Okhotsk Block, in NE Asia during the Late Cretaceous. In contrast, Type 2 sandstones were supplied only from the magmatic arc region that the Izanagi‐Pacific Ridge subduction could have activated. This provenance transition suggests the initially continental arc became separated from its continental source at the beginning of the Paleogene.
Plain Language Summary
Understanding the origin of the Paleo‐Kuril Arc is important for the plate tectonic history of the NW Pacific region. It is closely related to controversy regarding subduction of the oceanic ridge that may have existed between the Izanagi and Pacific Plates. This study aims at testing the hypothesis that the Paleo‐Kuril Arc system developed as an intraoceanic arc along the boundary between two oceanic plates. Detrital zircon U‐Pb age distributions from sandstones of the Nemuro and Urahoro Groups of the Paleo‐Kuril Arc terrain are examined. If the Paleo‐Kuril Arc was a volcanic arc formed between oceanic plates associated sandstones should not contain craton‐derived detrital zircon grains of Precambrian age. Detrital zircons of Precambrian age are common in Upper Cretaceous sandstones of the Nemuro Group, suggesting that the Paleo‐Kuril Arc developed as a continental arc system rather than an intraoceanic arc system. A new model in which a continental Paleo‐Kuril Arc emerged initially at the southern end of the Okhotsk Block during the Late Cretaceous and later split from continental cratons due to southward translation of this terrain is proposed.
Key Points
Detrital zircon ages indicate that the Paleo‐Kuril Arc developed as a continental rather than intraoceanic arc
Precambrian‐Cretaceous zircons in Cretaceous sandstones indicate continental craton provenance
Paleogene sandstones contain few pre‐Cretaceous zircon grains, suggest a significant shift in provenance
Aims
We investigated whether Listeria monocytogenes strains differ in their ability to escape from the primary phagosome after internalization into human intestinal epithelial cells.
Methods and ...Results
Food and clinical strains were used to study specific alleles; the activities of listeriolysin O (LLO) and phospholipases PlcA and PlcB, which promote rupture of the phagocytic vacuole; and initial intracellular bacterial growth in Caco‐2 cells. Results showed no difference in LLO activities between food and clinical strains or among serotypes. In contrast, the LLO truncation mutant lacked detectable haemolytic activity and intracellular growth. PlcA and PlcB produced by the strains of serotypes 4b/4e and 1/2b exhibited significantly lower activities than those of serotypes 1/2a and 1/2c. In contrast, the strains of serotype 1/2b grew significantly faster than those of serotypes 4b/4e and 1/2a. Moreover, the PrfA truncation mutants lacked LLO and phospholipases activities and did not show intracellular growth.
Conclusions
We determined that LLO and PrfA mutants exert a significant effect on intracellular growth, although it was unclear from this study whether PlcA and PlcB alleles affect escape from vacuoles.
Significance and Impact of the Study
This study estimates that low‐virulence L. monocytogenes strains associated with escape ability from the primary vacuoles are not widely distributed among food strains.
The adrenomedullin receptor is a complex molecule that comprises the calcitonin-receptor-like receptor (CRLR) and the receptor-activity-modifying protein (RAMP). RAMP1 is a vasodilation factor, and ...RAMP1-deficient mice (RAMP1(-/-)) exhibit inflammatory responses with a significant transient increase in serum calcitonin-gene-related peptide levels and proinflammatory cytokines when compared with RAMP1(+/+) mice. The purpose of the present study was to investigate the relationships between essential hypertension (EH) and RAMP1 gene single-nucleotide polymorphisms (SNPs) or haplotypes in a Japanese population via a case-control study. Based on a database search of the National Center of Biotechnology Information website and the HapMap project, we chose six RAMP1 gene SNPs and performed an association study involving 263 patients with EH and 267 age-matched normotensive (NT) subjects. There was no significant difference between the EH and NT groups with regard to overall distribution of genotypes or SNP alleles. However, the haplotype-based case-control analysis revealed that there was a significant difference between the EH and NT groups with regard to overall distribution of the allele combinations at three SNPs-rs3754701-rs3769048-rs10199956-(P=0.002). The T-A-T haplotype was significantly more common in the EH group (10.3%) than in the NT control group (6.1%) (P=0.047). These results suggested that this T-A-T RAMP1 gene haplotype might have utility as a genetic marker for EH and that the RAMP1 gene or a neighbouring gene may be associated with increased susceptibility to EH.
The inferior petrosal sinus (IPS) is the main transvenous access route used to examine or treat lesions involving the cavernous sinus. To carry out these procedures successfully, one must have a ...detailed knowledge of the anatomy of the venous system around the junction of the IPS and the internal jugular vein (IJV).
Eighty-three sides in 63 patients (26 men, 37 women; mean, 56.5 years of age) were examined by using 3D rotational venography (3DRV).
The drainage patterns of the IPS could be classified into the following 6 types, with emphasis on the level of IPS-IJV junction: type A, the IPS drains into the jugular bulb in 1/83 sides (1.2%); type B, the IPS drains into the IJV at the level of the extracranial opening of the hypoglossal canal in 29/83 sides (34.9%); type C, the IPS drains into the lower extracranial IJV in 31/83 sides (37.3%); type D, the IPS forms a plexus and has multiple junctions to the IJV near the jugular foramen in 5/83 sides (6.0%); type E, the IPS drains directly into the vertebral venous plexus (VVP) with no connection to the IJV in 3/83 sides (3.6%); and type F, the IPS is absent in 14/83 sides (16.9%). Each type is also characterized by the way of anastomosis with the VVP.
This classification seemed to be rational from the embryologic viewpoint, and it may be useful in establishing treatment strategies that involve endovascular manipulation via the IPS.
PDF
