A putative GDP–GTP exchange factor is required for development of the excretory cell in Caenorhabditis elegans

The Caenorhabditis elegans excretory cell extends tubular processes, called canals, along the basolateral surface of the epidermis. Mutations in the exc-5 gene cause tubulocystic defects in this canal. Ultrastructural analysis suggests that exc-5 is required for the proper placement of cytoskeletal elements at the apical epithelial surface. exc-5 encodes a protein homologous to guanine nucleotide exchange factors and contains motif architecture similar to that of FGD1, which is responsible for faciogenital dysplasia. exc-5 interacts genetically with mig-2, which encodes Rho GTPase. These results suggest that EXC-5 controls the structural organization of the excretory canal by regulating Rho family GTPase activities.     

Expression level of enzymes related to in situ estrogen synthesis and clinicopathological parameters in breast cancer patients

In order to evaluate the importance of estrogen production in tumor and surrounding tissues, we measured mRNA expression levels of 5 enzymes participating to estrogen synthesis in situ and 4 breast cancer-related proteins in 27 pairs of tumor and non-malignant tissues. Steroid sulfatase (STS) mRNA was more frequently detected in tumor tissues rather than in their non-malignant counterparts. Estrogen sulfotransferase (EST) was constantly expressed with high level not only in tumor tissues but also in their surrounding non-malignant counterparts. In contrast, mRNA expression levels of aromatase, and 17β-hydroxysteroid dehydrogenase type I and II were relatively low and detected only in small proportion of the patients. We also measured the mRNA expression levels of the same nine genes in tumor tissues of 197 breast cancer patients, and analyzed relationship between the mRNA expression level and the clinicopathological parameters. The mRNA expression levels of STS, aromatase and erbB2 in tumor tissues increased as breast cancer progressed. The tumoral mRNA expression levels of STS, estrogen receptor β, and erbB2 in patients with recurrence were higher than those in patients without recurrence. Upregulation of STS expression plays an important role in tumor progression of human breast cancer and is considered to be responsible for estrogen production in tumor and surrounding tissues.     

Changes in plasma thyroid hormones, luteinizing hormone (LH), estradiol, progesterone and corticosterone of laying hens during a forced molt

1. Circulating concentrations of iodothyronines, luteinizing hormone(LH), estradiol(E2), progesterone and corticosterone were measured in hens before, during, and after a forced molt induced by fasting. 2. Corticosterone increased at the onset of molt, peaked at the maximal molt and returned to pre- and post-molt levels. LH, E2 and progesterone declined during the molt, and the decline was coincident with the cessation of egg production. 3. Thyroxine(T4), triiodothyronine (T3) and reverse triiodothyronine(rT3) increased during the molt. The increases of T4 and T3 were not abolished even if the forced molt was conducted in mild weather.     

Calcium-activated neutral protease inhibitor from rabbit erythrocytes lacks the N-terminal region of the liver inhibitor but retains three inhibitory units

Endogenous inhibitors for calcium-activated neutral protease (CANP) were purified from rabbit erythrocytes and liver. The purified inhibitors showed single bands but with significantly different mobilities on sodium dodecylsulfate-polyacrylamide gel electrophoresis. Peptide mapping and sequencing analyses have revealed that the erythrocyte inhibitor (429 residues) retains the C-terminal three repetitive units of the liver inhibitor (639 residues), which contains four potential repetitive units for inhibition of CANP. The erythrocyte and liver inhibitors inhibited 3 and 4 moles of CANP on the basis of the molecular weights of 46,000 and 68,000, respectively.     

Aggregatibacter actinomycetemcomitans induces detachment and death of human gingival epithelial cells and fibroblasts via elastase release following leukotoxin‐dependent neutrophil lysis

Aggregatibacter actinomycetemcomitans is considered to be associated with periodontitis. Leukotoxin (LtxA), which destroys leukocytes in humans, is one of this bacterium's major virulence factors. Amounts of neutrophil elastase (NE), which is normally localized in the cytoplasm of neutrophils, are reportedly increased in the saliva of patients with periodontitis. However, the mechanism by which NE is released from human neutrophils and the role of NE in periodontitis is unclear. In the present study, it was hypothesized that LtxA induces NE release from human neutrophils, which subsequently causes the breakdown of periodontal tissues. LtxA‐treatment did not induce significant cytotoxicity against human gingival epithelial cells (HGECs) or human gingival fibroblasts (HGFs). However, it did induce significant cytotoxicity against human neutrophils, leading to NE release. Furthermore, NE and the supernatant from LtxA‐treated human neutrophils induced detachment and death of HGECs and HGFs, these effects being inhibited by administration of an NE inhibitor, sivelestat. The present results suggest that LtxA mediates human neutrophil lysis and induces the subsequent release of NE, which eventually results in detachment and death of HGECs and HGFs. Thus, LtxA‐induced release of NE could cause breakdown of periodontal tissue and thereby exacerbate periodontitis.     

Gap Junctions Mediate Glucose Transport Between GLUT1-Positive and -Negative Cells in the Spiral Limbus of the Rat Cochlea

To elucidate the role of the spiral limbus in glucose transport in the cochlea, we analyzed the expression and localization of GLUT1, connexin26, connexin30, and occludin in the spiral limbus of the rat cochlea. GLUT1 and occludin were detected in blood vessels. GLUT1, connexin26, connexin30, and occludin were also expressed in fibrocytes just basal to the supralimbal lining cells. Connexin26 and connexin30 were present among not only these GLUT1-positive fibrocytes but also GLUT1-negative fibrocytes. In vivo glucose imaging using 6-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-6-deoxyglucose (6-NBDG, MW 342) together with Evans Blue Albumin (EBA, MW 68,000) showed that 6-NBDG was rapidly distributed throughout the spiral limbus, whereas EBA was localized only in the vessels. Moreover, the gap junctional uncoupler heptanol inhibited the distribution of 6-NBDG. These findings suggest that gap junctions play an important role in glucose transport in the spiral limbus, i.e., that gap junctions mediate glucose transport from GLUT1-positive fibrocytes to GLUT1-negative fibrocytes in the spiral limbus.     

Neoplastic cell transformation by heavy ions

We have studied the induction of morphological transformation by heavy ions. Golden hamster embryo cells were irradiated with 95 MeV 14N ions (530 keV/microns), 22 MeV 4He ions (36 keV/microns), and 22 MeV 4He ions with a 100-microns Al absorber (77 keV/microns) which were generated by a cyclotron at the Institute of Physical and Chemical Research in Japan. Colonies were considered to contain neoplastically transformed cells when the cells were densely stacked and made a crisscross pattern. It was shown that the induction of transformation was much more effective with 14N and 4He ions than with gamma or X rays. The relative biological effectiveness (RBE) relative to 60Co gamma rays was 3.3 for 14N ions, 2.4 for 4He ions, and 3.3 for 4He ions with a 100-microns Al absorber. The relationship between RBE and linear energy transfer was qualitatively similar for both cell death and transformation.