Pathogenesis of persistent truncus arteriosus induced by nimustine hydrochloride in chick embryos

Nimustine hydrochloride (ACNU) is a nitrosourea derivative anticancer agent which has been shown to cause persistent truncus arteriosus in chick embryos. The objective of this study was to confirm the teratogenic effects of ACNU on the cardiovascular system of chick embryos and to determine whether ACNU induces persistent truncus arteriosus by interfering with neural crest cells. Various doses of ACNU ranging from 10 to 200 micrograms were injected under the chorioallantoic membrane of chick embryos on the third day of incubation. Saline solution was used as the control. After 10 to 11 days of incubation, 242 (46%) survivors of the 524 treated eggs were obtained. The survival rates of the embryos and the frequencies of cardiovascular anomalies were dose dependent. Of 146 embryos with cardiovascular anomalies, 104 (71%) had persistent truncus arteriosus. Ventricular septal defect and double-outlet right ventricle were seen in 37 (25%) and one (1%), respectively. Aortic arch anomalies were seen in 116 embryos (79%). Quail-chick chimeras (chick embryos with quail cardiac neural crest) were treated with 50 micrograms of ACNU and examined histologically 24 hours later. These chimeras showed dying neural crest cells in the pharyngeal arches. Dying cells were also noted in the neural tube, cranial ganglia, retina, and otocyst. These results suggest that persistent truncus arteriosus in chick embryos treated with ACNU is induced by neural crest cell death.     

Effect of C-reactive protein on peritoneal macrophages. II. Human C-reactive protein activates peritoneal macrophages of guinea pigs to release superoxide anion in vitro

The effect of human C-reactive protein (CRP) on macrophage function was studied in an assay of superoxide anion (O2-) production. Peritoneal exudate macrophages (PEM) of guinea pigs exposed in vitro to various doses of CRP for 72 hr resulted in the development of O2- production dose-dependently, measured by increases in superoxide dismutase-inhibitable nitro blue tetrazolium reduction. The O2--producing activity of PEM cultured without CRP, used as a control, decreased markedly in proportion to incubation time. The O2- production by PEM exposed to CRP for 18 hr when control PEM were still high in O2- production, was decreased by larger doses of CRP, while PEM cultured without CRP for 72 hr, when O2- production by control PEM was very low, followed by incubation with CRP for another 18 hr, produced O2- CRP-dose-dependently as in the case of that observed after 72-hr incubation with CRP. These results indicate that CRP is capable of activating macrophages and acts on macrophage function as a modulator. CRP possesses migration inhibitory factor (MIF)-like activity (as reported in the preceding paper) and also macrophage-activating factor (MAF)-like activity, indicating that CRP may play a functional role at the site of inflammation and tissue damage by accumulating and activating macrophages.     

Studies on hst, a transforming gene which belongs to a new superfamily of growth factors

The hst gene was originally identified in surgically obtained human gastric mucosae as a transforming gene which could transform NIH3T3 cells morphologically. The hst cDNA clone was synthesized from mRNA of one of the NIH3T3 transformants. A human leukocyte genomic library was screened with this cDNA clone, and an hst genomic fragment was obtained. This genomic fragment itself had transforming activity, and the protein coding sequences were proved to be completely identical to those of the cDNA clone prepared from mRNA of the NIH3T3 transformant. This fact suggests that rearrangement or other structural alterations in the coding sequence are not required for the activation of the hst gene. The predicted hst protein consists of 206 amino acids and has a significant homology (40-50%) to fibroblast growth factors and int-2 protein. They together make up a new superfamily of growth factors and transforming genes.     

The role of p63 in embryonic external genitalia outgrowth in mice

Embryonic external genitalia (genital tubercle [GT]) protrude from the cloaca and outgrow as cloacal development progresses. Individual gene functions and knockout phenotypes in GT development have been extensively analyzed; however, the interactions between these genes are not fully understood. In this study, we investigated the role of p63, focusing on its interaction with the Shh–Wnt/Ctnnb1–Fgf8 pathway, a signaling network that is known to play a role in GT outgrowth. p63 was expressed in the epithelial tissues of the GT at E11.5, and the distal tip of the GT predominantly expressed the ΔNp63α isoform. The GTs in p63 knockout embryos had normal Shh expression, but CTNNB1 protein and Fgf8 gene expression in the distal urethral epithelium was decreased or lost. Constitutive expression of CTNNB1 in p63-null embryos restored Fgf8 expression, accompanied by small bud structure development; however, such bud structures could not be maintained by E13.5, at which point mutant GTs exhibited severe abnormalities showing a split shape with a hemorrhagic cloaca. Therefore, p63 is a key component of the signaling pathway that triggers Fgf8 expression in the distal urethral epithelium and contributes to GT outgrowth by ensuring the structural integrity of the cloacal epithelia. Altogether, we propose that p63 plays an essential role in the signaling network for the development of external genitalia.     

Fine structural studies on the reabsorption of colloid and fusion of colloid droplets in thyroid glands of TSH-treated mice

Summary The mechanism of the luminal colloid reabsorption and the fate of reabsorbed colloid droplets were studied ultracytochemically in epithelial cells of thyroid cells of TSH-treated mice. The luminal colloid is reabsorbed by micropinocytosis as well as phagocytosis into the follicle epithelial cell. Almost all the pinocytotic pits and vesicles are coated and often closely associated with actin filaments demonstrated by use of heavy meromyosin (HMM). This suggests the involvement of the actin filament system in making and transporting coated vesicles for micropinocytosis of the luminal colloid. Freeze-fracture images show aggregates of intramembrane particles on the P-face of the small depressions corresponding to the initial site for coated pits.The reabsorbed colloid droplets fuse with one another and with lysosomes. At the initial stage of this fusion, the limiting membranes of adjoining droplets fuse in a limited area to become pentalaminar, and then become trilaminar. Eventually, the membranes at the fusion point disappear, and the contents of both droplets become continuous. Freeze-fracture images reveal the disappearance of the intramembrane particles at the initial site where the fusion occurs.Examination of thin-sectioned tissue treated by rapid-freeze substitution fixation, shows clearly delineated cell organelles, and the rounded mitochondria have a characteristically high electron-dense matrix. Just beneath the limiting membrane of each colloid droplet, there always exists a low electron-dense layer about 10 nm thickness. The lysosomes are sometimes seen wrapped around the colloid droplet.This study was supported by grants (No. 56370002, No. 00544016) from the Japan Ministry of Education     

The size of the corpus luteum during pseudopregnancy and pregnancy in the rat.

The corpus luteum in mature Sprague Dawley rats was weighted at the various stages of pseudopregnancy and pregancy. The average size of these corpora lutea was 1.0 +/- 0.10 mg, 1.61 +/- 0.69 mg, 1.90 +/- 0.25 mg, 3.69 +/- 0.36 mg, and 4.37 +/- 0.50 mg on day 2 of diestrus, on days 10-15 of psuedopregnancy, on days 9-10, 14, and 20 of pregnancy, respectively. The fact that the average size of the corpus luteum on days 10-15 of pseudopregnancy was larger than that on day 2 of diestrus is thought to drive from prolonged exposure of the corpus luteum to prolactin. The average size of the corpus luteum on days 9-10 of pregnancy had a tendency to be larger than that on days 10-15 of pseudopregnancy and this seems to demonstrate that the placenta secreted placental lactogen by this stage of pregnancy. The average size of the corpus luteum on day 14 of pregnancy was larger than that on days 9-10 of pregnancy. This phenomenon might be attributed to the presence of large amounts of placental lactogen secreted from the placenta between days 10 and 14 of pregnancy. Furthermore, it was noted that the size of the corpus luteum on day 20 of pregnancy was larger than that of day 14, which suggests that further secretion of placental lactogen continued after day 14 of pregnancy. As there was a remarkable decrease in the number of fetuses on day 20 of pregnancy when overiectomy was performed on day 14 of pregnancy, the ovary was considered indispensable in maintaining pregnancy in the rat.     

Essential contribution of germline-encoded lysine residues in Jgamma1.2 segment to the recognition of nonpeptide antigens by human gammadelta T cells.

Human gammadelta T cells display unique repertoires of Ag specificities largely imposed by selective usages of distinct Vgamma and Vdelta genes. Among them, Vgamma2/Vdelta2(+) T cells predominate in the circulation of healthy adults and respond to various microbial small molecular mass nonpeptide Ags. The present results indicate that the primary Vgamma2/Vdelta2(+) T cells stimulated with the distinct groups of nonpeptide Ags, including monoethyl pyrophosphate, isobutyl amine, and aminobisphosphonate, invariably exhibit Jgamma1.2 in the Vgamma2(+) TCR-gamma chains. Gene transfer studies revealed that most of the randomly cloned Vgamma2/Jgamma1.2(+) TCR-gamma genes bearing diverse Vgamma/Jgamma junctional sequences could confer the responsiveness to all these nonpeptide Ags, while none of the Vgamma2/Jgamma1.1(+) or Vgamma2/Jgamma1.3(+) TCR-gamma genes could do so. Furthermore, mutation of the lysine residues encoded by the Jgamma1.2 gene, which are unique in human Jgamma1.2 and absent in other human or mouse Jgamma segments, completely abrogated the responsiveness to all the nonpeptide Ags without affecting the response to anti-CD3 mAb. These results strongly suggested that the positively charged lysine residues in the TCR-gamma chain CDR3 region encoded by the germline Jgamma1.2 gene play a key role in the recognition of diverse small molecular mass nonpeptide Ags.     

Decrease in bacterial production over the past three decades in the north basin of Lake Biwa,Japan

Limnology - In Lake Biwa, the largest lake in Japan, external pollutant loads have decreased since the 1980s, leading to improved water quality, such as reduction in biochemical oxygen demand (BOD)...     

Hyperthermia inhibits homologous recombination repair and sensitizes cells to ionizing radiation in a time‐ and temperature‐dependent manner

Hyperthermia has long been known as a radio‐sensitizing agent that displays anti‐tumor effects, and has been developed as a therapeutic application. The mechanisms of hyperthermia‐induced radio‐sensitization are highly associated with inhibition of DNA repair. Our investigations aimed to show how hyperthermia inactivate homologous recombination repair in the process of sensitizing cells to ionizing radiation by using a series of DNA repair deficient Chinese Hamster cells. Significant differences in cellular toxicity attributable to hyperthermia at and above 42.5°C were observed. In wild‐type and non‐homologous end joining repair mutants, cells in late S phase showed double the amount heat‐induced radio‐sensitization effects of G1‐phase cells. Both radiation‐induced DNA double strand breaks and chromatin damage resulting from hyperthermia exposure was measured to be approximately two times higher in G2‐phase cells than G0/G1 cells. Additionally, G2‐phase cells took approximately two times as long to repair DNA damage over time than G0/G1‐phase cells. To supplement these findings, radiation‐induced Rad51 foci formations at DNA double strand break sites were observed to gradually dissociate in response to the temperature and time of hyperthermia exposure. Dissociated Rad51 proteins subsequently re‐formed foci at damage sites with time, and occurred in a trend also related to temperature and time of hyperthermia exposure. These findings suggest Rad51's dissociation and subsequent reformation at DNA double strand break sites in response to varying hyperthermia conditions plays an important role in hyperthermia‐induced radio‐sensitization. J. Cell. Physiol. 228: 1473–1481, 2013. © 2012 Wiley Periodicals, Inc.