Temperature-Dependent Electron Momentum Spectroscopy on the Molecular Orbitals of Dimethyl Ether.

This paper investigates vibrational excitation effects on valence electron momentum distributions of dimethyl ether. A symmetric noncoplanar (e, 2e) experiment has been performed for the molecule at a high temperature (980 K) as well as at room temperature (300 K). For comparison, theoretical calculations with vibrational effects being involved have also been carried out. Changes of the momentum profiles with the rise of temperature are observed for the 2b1 and 6a1 orbitals, indicating that distortion of these molecular orbitals is appreciably enhanced upon excitation of the methyl torsional vibrations. The present study provides a way for exploring the influence of vibrational excitation on electronic wavefunctions of molecules.

Electron momentum spectroscopy study on the valence electronic structure of methyl formate.

We report an electron momentum spectroscopy study on methyl formate. A symmetric noncoplanar (e, 2e) experiment has been performed at an incident electron energy of 1.2 keV and electron momentum profiles of the valence orbitals have been obtained. On the basis of the result, assignments of the 10a'-1 and 1a″-1 bands have been made to resolve a contradiction between photoelectron spectroscopy and Penning ionization electron spectroscopy studies. Comparisons between experiment and theory reveal that the influence of the molecular vibration has to be taken into account for a proper understanding of the electron momentum profiles. Contributions of individual vibrational normal modes have also been investigated in detail by means of the harmonic analytical quantum mechanical approach.

Upper extremity muscle tone and response of tidal volume during manually assisted breathing for patients requiring prolonged mechanical ventilation.

[Purpose] The aim of the present study was to examine, in patients requiring prolonged mechanical ventilation, if the response of tidal volume during manually assisted breathing is dependent upon both upper extremity muscle tone and the pressure intensity of manually assisted breathing. [Subjects] We recruited 13 patients on prolonged mechanical ventilation, and assessed their upper extremity muscle tone using the modified Ashworth scale (MAS). The subjects were assigned to either the low MAS group (MAS≤2, n=7) or the high MAS group (MAS≥3, n=6). [Methods] The manually assisted breathing technique was applied at a pressure of 2 kgf and 4 kgf. A split-plot ANOVA was performed to compare the tidal volume of each pressure during manually assisted breathing between the low and the high MAS groups. [Results] Statistical analysis showed there were main effects of the upper extremity muscle tone and the pressure intensity of the manually assisted breathing technique. There was no interaction between these factors. [Conclusion] Our findings reveal that the tidal volume during the manually assisted breathing technique for patients with prolonged mechanical ventilation depends upon the patient's upper extremity muscle tone and the pressure intensity.

Test-retest reliability of expiratory abdominal compression with a handheld dynamometer in patients with prolonged mechanical ventilation.

[Purpose] The present study aimed to examine the test-retest reliability of expiratory abdominal compression with a handheld dynamometer in patients with prolonged mechanical ventilation. [Subjects and Methods] We recruited 18 patients with prolonged mechanical ventilation. All patients had impaired consciousness. The mode of the ventilator was synchronized intermittent mandatory ventilation. The abdomen above the navel was vertically compressed using a handheld dynamometer in synchronization with expiration. Expiratory abdominal compression was performed two times. We measured the tidal volume during expiratory abdominal compression. There was an interval of 5 minutes between the first and second measurements. Intraclass correlation coefficient (ICC) and Bland-Altman analysis were performed to examine the test-retest reliability of expiratory abdominal compression with a handheld dynamometer. [Results] The test-retest reliability of expiratory abdominal compression was excellent (ICC(1, 1): 0.987). Bland-Altman analysis showed that there was no fixed bias and no proportional bias. [Conclusion] The findings of this study suggest that expiratory abdominal compression with a handheld dynamometer is reliable and useful for patients with respiratory failure and prolonged mechanical ventilation.

Parameters affecting the tidal volume during expiratory abdominal compression in patients with prolonged tracheostomy mechanical ventilation.

[Purpose] The aim of this study was to clarify physical parameters affecting the tidal volume during expiratory abdominal compression in patients with prolonged tracheostomy mechanical ventilation. [Methods] Eighteen patients with prolonged mechanical ventilation were included in this study. Expiratory abdominal compression was performed on patients lying in a supine position. The abdomen above the navel was vertically compressed in synchronization with expiration and released with inspiration. We measured the tidal volume during expiratory abdominal compression. [Results] The mean tidal volume during expiratory abdominal compression was higher than that at rest (430.6 ± 127.1 mL vs. 344.0 ± 94.3 mL). The tidal volume during expiratory abdominal compression was correlated with weight, days of ventilator support, dynamic compliance and abdominal expansion. Stepwise multiple regression analysis revealed that weight (ß = 0.499), dynamic compliance (ß = 0.387), and abdominal expansion (ß = 0.365) were factors contributing to the tidal volume during expiratory abdominal compression. [Conclusion] Expiratory abdominal compression increased the tidal volume in patients with prolonged tracheostomy mechanical ventilation. The tidal volume during expiratory abdominal compression was influenced by each of the pulmonary conditions and the physical characteristics.

Comparison of changes in tidal volume associated with expiratory rib cage compression and expiratory abdominal compression in patients on prolonged mechanical ventilation.

[Purpose] This study was designed to compare and clarify the relationship between expiratory rib cage compression and expiratory abdominal compression in patients on prolonged mechanical ventilation, with a focus on tidal volume. [Subjects and Methods] The subjects were 18 patients on prolonged mechanical ventilation, who had undergone tracheostomy. Each patient received expiratory rib cage compression and expiratory abdominal compression; the order of implementation was randomized. Subjects were positioned in a 30° lateral recumbent position, and a 2-kgf compression was applied. For expiratory rib cage compression, the rib cage was compressed unilaterally; for expiratory abdominal compression, the area directly above the navel was compressed. Tidal volume values were the actual measured values divided by body weight. [Results] Tidal volume values were as follows: at rest, 7.2 ± 1.7 mL/kg; during expiratory rib cage compression, 8.3 ± 2.1 mL/kg; during expiratory abdominal compression, 9.1 ± 2.2 mL/kg. There was a significant difference between the tidal volume during expiratory abdominal compression and that at rest. The tidal volume in expiratory rib cage compression was strongly correlated with that in expiratory abdominal compression. [Conclusion] These results indicate that expiratory abdominal compression may be an effective alternative to the manual breathing assist procedure.

Bacteria-derived hydrogen sulfide promotes IL-8 production from epithelial cells.

Hydrogen sulfide (H(2)S), a volatile sulfur compound, is implicated as a cause of inflammation, especially when it is produced by bacteria colonizing gastrointestinal organs. However, it is unclear if H(2)S produced by periodontal pathogens affects the inflammatory responses mediated by oral/gingival epithelial cells. Therefore, the aims of this study were (1) to compare the in vitro production of H(2)S among 14 strains of oral bacteria and (2) to evaluate the effects of H(2)S on inflammatory response induced in host oral/gingival epithelial cells. Porphyromonas gingivalis (Pg) produced the most H(2)S in culture, which, in turn, resulted in the promotion of proinflammatory cytokine IL-8 from both gingival and oral epithelial cells. The up-regulation of IL-8 expression was reproduced by the exogenously applied H(2)S. Furthermore, the mutant strains of Pg that do not produce major soluble virulent factors, i.e. gingipains, still showed the production of H(2)S, as well as the promotion of epithelial IL-8 production, which was abrogated by H(2)S scavenging reagents. These results demonstrated that Pg produces a concentration of H(2)S capable of up-regulating IL-8 expression induced in gingival and oral epithelial cells, revealing a possible mechanism that may promote the inflammation in periodontal disease.

Hydrogen mediates suppression of colon inflammation induced by dextran sodium sulfate.

By its antioxidant effect, molecular hydrogen gas (H2) was reported to protect organs from tissue damage induced by ischemia reperfusion. To evaluate its anti-inflammatory effects, we established a mouse model of human inflammatory bowel disease (IBD) by supplying mice with water containing (1) dextran sodium sulfate (DSS) (5%), (2) DSS (5%) and H2, or (3) H2 only ad libitum up to 7 days. At day-7, DSS-induced pathogenic outcomes including, loss of body weight, increase of colitis score, pathogenic shortening of colon length, elevated level of IL-12, TNF-alpha and IL-1beta in colon lesion, were significantly suppressed by the addition of H2 to DSS solution. Histological analysis also revealed that the DSS-mediated colonic tissue destruction accompanied by macrophage infiltration was remarkably suppressed by H2. Therefore, the present study indicated that H2 can prevent the development of DSS-induced colitis in mice.

Hydrogen from intestinal bacteria is protective for Concanavalin A-induced hepatitis.

It is well known that some intestinal bacteria, such as Escherichia coli, can produce a remarkable amount of molecular hydrogen (H(2)). Although the antioxidant effects of H(2) are well documented, the present study examined whether H(2) released from intestinally colonized bacteria could affect Concanavalin A (ConA)-induced mouse hepatitis. Systemic antibiotics significantly decreased the level of H(2) in both liver and intestines along with suppression of intestinal bacteria. As determined by the levels of AST, ALT, TNF-alpha and IFN-gamma in serum, suppression of intestinal bacterial flora by antibiotics increased the severity of ConA-induced hepatitis, while reconstitution of intestinal flora with H(2)-producing E. coli, but not H(2)-deficient mutant E. coli, down-regulated the ConA-induced liver inflammation. Furthermore, in vitro production of both TNF-alpha and IFN-gamma by ConA-stimulated spleen lymphocytes was significantly inhibited by the introduction of H(2). These results indicate that H(2) released from intestinal bacteria can suppress inflammation induced in liver by ConA.

Maternal Nanos represses hid/skl-dependent apoptosis to maintain the germ line in Drosophila embryos.

Nanos (Nos) is an evolutionarily conserved protein essential for the survival of primordial germ cells. In Drosophila, maternal Nos partitions into pole cells and suppresses apoptosis to permit proper germ-line development. However, how this critical event is regulated by Nos has remained elusive. Here, we report that Nos represses apoptosis of pole cells by suppressing translation of head involution defective (hid), a member of the RHG gene family that is required for Caspase activation. In addition, we demonstrate that hid acts in concert with another RHG gene, sickle (skl), to induce apoptosis. Expression of skl is induced in pole cells by maternal tao-1, a ste20-like serine/threonine kinase. Tao-1-dependent skl expression is required to potentiate hid activity. However, skl expression is largely suppressed in normal pole cells. Once the pole cells lack maternal Nos, Tao-1-dependent skl expression is fully activated, suggesting that skl expression is also restricted by Nos. These findings provide the first evidence that the germ line is maintained through the regulated expression of RHG genes.

Identification and origin of the germline stem cells as revealed by the expression of nanos-related gene in planarians.

The planarian's remarkable regenerative ability is thought to be supported by the stem cells (neoblasts) found throughout its body. Here we report the identification of a subpopulation of neoblasts, which was revealed by the expression of the nanos-related gene of the planarian Dugesia japonica, termed Djnos. Djnos-expressing cells in the asexual planarian were distributed to the prospective ovary or testes forming region in the sexual planarian. During sexualization, Djnos-expressing cells produce germ cells, suggesting that in the asexual state these cells were kept as germline stem cells for the oogonia and spermatogonia. Interestingly, the germline stem cells were indistinguishable from the neoblasts by morphology and X-ray sensitivity and did not seem to contribute to the regeneration at all. Germline stem cells initially appear in the growing infant planarian, suggesting that germline stem cells are separated from somatic stem cells in the planarian. Thus, planarian neoblasts can be classified into two groups; somatic stem cells for regeneration and tissue renewal, and germline stem cells for production of germ cells during sexualization. However, Djnos-positive cells appeared in the newly formed trunk region from the head piece, suggesting that somatic stem cells can convert to germline stem cells.

The role of mitochondrial rRNAs and nanos protein in germline formation in Drosophila embryos.

Germ cells, represented by male sperm and female eggs, are specialized cells that transmit genetic material from one generation to the next during sexual reproduction. The mechanism by which multicellular organisms achieve the proper separation of germ cells and somatic cells is one of the longest standing issues in developmental biology. In many animal groups, a specialized portion of the egg cytoplasm, or germ plasm, is inherited by the cell lineage that gives rise to the germ cells (germline). Germ plasm contains maternal factors that are sufficient for germline formation. In the fruit fly, Drosophila, germ plasm is referred to as polar plasm and is distinguished histologically by the presence of polar granules, which act as a repository for the maternal factors required for germline formation. Molecular screens have so far identified several of these factors that are enriched in the polar plasm. This article focuses on the molecular functions of two such factors in Drosophila, mitochondrial ribosomal RNAs and Nanos protein, which are required for the formation and differentiation of the germline progenitors, respectively.

Role of mitochondrial ribosome-dependent translation in germline formation in Drosophila embryos.

In Drosophila, mitochondrially encoded ribosomal RNAs (mtrRNAs) form mitochondrial-type ribosomes on the polar granules, distinctive organelles of the germ plasm. Since a reduction in the amount of mtrRNA results in the failure of embryos to produce germline progenitors, or pole cells, it has been proposed that translation by mitochondrial-type ribosomes is required for germline formation. Here, we report that injection of kasugamycin (KA) and chloramphenicol (CH), inhibitors for prokaryotic-type translation, disrupted pole cell formation in early embryos. The number of mitochondrial-type ribosomes on polar granules was significantly decreased by KA treatment, as shown by electron microscopy. In contrast, ribosomes in the mitochondria and mitochondrial activity were unaffected by KA and CH. We further found that injection of KA and CH impairs production of Germ cell-less (Gcl) protein, which is required for pole cell formation. The above observations suggest that mitochondrial-type translation is required for pole cell formation, and Gcl is a probable candidate for the protein produced by this translation system.