Tuning of the porin expression under anaerobic growth conditions by his-to-Asp cross-phosphorelay through both the EnvZ-osmosensor and ArcB-anaerosensor in Escherichia coli

BACKGROUND: Widespread bacterial signal transduction circuits are generally referred to as 'two-component systems' or 'histidine (His)-to-aspartate (Asp) phosphorelays.' In Escherichia coli, as many as 30 distinct His-to-Asp phosphorelay signalling pathways operate in response to a wide variety of environmental stimuli, such as medium osmolarity and anaerobiosis. In this regard, it is of interest whether or not some of them together constitute a network of signalling pathways through a physiologically relevant mechanism (often referred to as 'cross-regulation'). We have addressed this issue, with special reference to the osmo-responsive EnvZ and anaero-responsive ArcB phosphorelay signalling pathways in E. coli. RESULTS: Under standard aerobic growth conditions, it is well known that the osmoregulatory profile of the outer membrane porins (OmpC and OmpF) is mainly regulated by the EnvZ-OmpR phosphorelay system in response to medium osmolarity. In this study, it was found that, under anaerobic growth conditions, E. coli cells exhibit a markedly altered expression profile of OmpC and OmpF This profile was significantly different from that observed for the cells grown aerobically. Results from extensive genetic studies showed that, under such anaerobic growth conditions, the arcB gene encoding the anaero-sensory His-kinase appears to be an auxiliary genetic determinant that regulates the expression profile of porins. We then provided several lines of in vivo and in vitro evidence, which taken together, supported the following conclusions. CONCLUSIONS: Under anaerobic growth conditions, porin expression is tuned not only by the authentic osmo-resposive EnvZ sensor, but also by the anaero-responsive ArcB sensor, in an OmpR-dependent manner. It is suggested that such ArcB-mediated cross-regulation plays a physiological role by integrating anaerobic respiratory signals into the porin regulation in E. coli anaerobiosis. The proposed model is a clear example of the interplay of two distinct His-to-Asp phosphorelay signalling pathways.     

Parosteal fasciitis of the clavicle

A rare case of parosteal fasciitis arising from the periosteum of the left clavicle in a 27-year-old woman is reported. Magnetic resonance imaging demonstrated the lesion surrounding the periosteum of the clavicle. The lesion was iso-intense with muscle on T(1)-weighted images and hyperintense on T(2)-weighted images. At surgery, the lesion was discovered to be densely adherent with the periosteum, and excised along with the periosteum. Histopathological examination revealed the proliferation of myofibroblasts in a vague storiform or short fascicular pattern. A large amount of extravasated erythrocytes, and a few lymphocytes were present in the matrix. There were some foci of abundant myxoid materials. Immunohistochemical study showed the cells to be positive for vimentin, alpha-smooth muscle actin and HHF35, but negative for desmin. There was no local recurrence at a 6 months postoperative follow up.     

Virus-associated hemophagocytic syndrome: the diagnostic usefulness of immature histiocytes with benign features in the bone marrow

A 2-year-old girl developed fever, hepatosplenomegaly, jaundice, lymphadenopathy and pancytopenia. Bone marrow examination revealed increased immature histiocytes (5.5%) and mature histiocytes with hemophagocytosis. All the abnormalities were normalized in one month without any chemotherapy. It was suggested that the presence of immature histiocytes with benign features, even if their number exceeds that of mature histiocytes, does not favor the diagnosis of malignant histiocytosis.     

Grading score system: A method for evaluation of the degree of senescence in Senescence Accelerated Mouse (SAM)

For evaluation of the degree of senescence in SAM-P, accelerated senescence prone mouse, formerly called SAM or prone series or P-series, consisting of SAM-P/1, SAM-P/2, SAM-P/3 and SAM-P/4 corresponding to P-1, P-2, P-3 and P-4 series, respectively, in the previous reports, and in SAM-R, accelerated senescence resistant mouse, formerly called resistant series or R-series, consisting of SAM-R/1, SAM-R/2 and SAM-R/3 corresponding to R-1, R-2 and R-3 series, respectively, in the previous reports, the grading score system was adopted. The items to be examined in this system include 11 categories selected from the clinical signs and gross lesions considered to be associated with the aging process. The degree of the senescence in each category was graded from 0 to 4 according to the detailed criteria devised in our laboratory. After 8 months of age each mouse was examined every 4 months, and some of the mice were examined after 2 months of age.In almost all categories, the grading score and incidence began to increase from 4 or 6 months of age and continued to increase with advancing age in both SAM-P and SAM-R. The increase, however, was more marked in SAM-P than in SAM-R. The slow but steady increase in the SAM-R levelled out at 24 months of age and was comparable to that of 12 months of age in SAM-P. In both SAM-P/1 at 8 months of age and SAM-R/2 at 12 months of age, there was a significant reverse correlation between total score of this grading score system and length of residual life after examination.Systematic and extensive studies using the grading score system showed that if the validity of the system is, based on “irreversibility” and “universality” of the changes in     

Age- and sex-related changes in toluene metabolism by rat hepatic microsomes in vitro

Age- and sex-related changes in toluene metabolism by hepatic microsomes of male and female Sprague-Dawley (SD) rats (1 to 20 weeks) were investigated. A major metabolite of toluene, benzyl alcohol (BA), was measured by high-performance liquid chromatography (HPLC). At low substrate toluene concentrations (0.4 mM), in male rats, BA increased dramatically with development, reaching a peak at 5 weeks of age, rapidly decreasing thereafter. In female rats, BA increased dramatically with development at 3 to 5 weeks of age, and then declined gradually to a low level. Gender differences were obtained at 5 and 20 weeks of age, with BA products being higher in males than in females. At high substrate toluene concentrations (5.0 mM), in male rats, the BA formation pattern was similar to that at the low substrate concentration, although the rate of increase with age was slower. In female rats, a peak was obtained at 3 weeks of age, and then declined gradually to a low level. Gender differences were obtained at 5, 15 and 20 weeks of age, with BA products being higher in males than in females. These results indicate that toluene metabolism exhibits age and gender differences.     

Morphological evidence for axonal sprouting of cerebellothalamic neurons in kittens after neonatal hemicerebellectomy

Summary Changes in cerebellothalamic projections in kittens after neonatal hemicerebellectomy were studied by the retrograde and anterograde horseradish peroxidase (HRP)-tract-tracing methods. The number of cerebellar nuclear neurons labeled retrogradely with HRP injected into the ipsilateral VA-VL complex of the thalamus was much more numerous in neonatally hemicerebellectomized kittens than in intact kittens. Presumed terminals of ipsilateral cerebellothalamic fibers labeled anterogradely with HRP injected into the cerebellar nuclei were also distributed more densely and extensively in the thalamic areas, especially in the VA-VL complex, of hemicerebellectomized kittens than in the thalamic areas of the control kittens. These results are in good accordance with those obtained from the previous electrophysiological study (Kawaguchi et al., 1979) and offer corroborating evidence for axonal sprouting of cerebellothalamic neurons after neonatal hemicerebellectomy.     

Localization of motoneurons innervating the posterior belly of the digastric muscle: a comparative anatomical study by the HRP method.

Motoneurons innervating the posterior belly of the digastric muscle were identified in the monkey, cat, dog, guinea pig and rat by the HRP method. After injections of horseradish peroxidase (HRP) into the posterior belly of the digastric muscle, two groups of HRP-labeled motoneurons were observed; the rostral group was seen as a small cluster of neurons in the lateral reticular area along the medial border of the descending root of the facial nerve, and the neurons of the caudal group were distributed among the ascending root fibers of the facial nerve. The distribution pattern of these neurons corresponded to that of the accessory facial nucleus neurons. The accessory facial nucleus was lacking in the rabbit in which the posterior digastric (PD) muscle is nonexistent.     

Development of an experimental apparatus for investigating lymphatic pumping activity of murine mesentery in vivo

The present study has been attempted to establish a modified intravital microscope system for investigating murine lymphatic pumping activity in vivo and evaluate whether or not there is rhythmic pumping activity of murine mesenteric lymphatic vessels in vivo. We designed and constructed a custom organ chamber with a semicircular channel (8 mm in radius, 5 mm in width, 3 mm in depth), being suitable for the superfusing of murine mesentery in vivo. A marked lymphatic pumping activity was observed in the mesenteries of DDY mice. The maximal and minimal diameter and frequency in the pumping activity were 60.9 +/- 1.0 microm, 53.7 +/- 1.8 microm and 12.8 min(-1) (n = 5), respectively. Both NE (norepinephrine, 10(-8)-10(-6) M) and TEA (tetraethylammonium, 1-10 mM) caused dose-dependent constriction of the mesenteric lymphatic vessels in the mice. These findings suggest that a modified intravital microscope system with a specially designed and constructed edge-monitoring device enables us to investigate in vivo lymphatic circulation in murine mesenteries.     

The plasminogen activation system reduces fibrosis in the lung by a hepatocyte growth factor-dependent mechanism

Mice deficient in the plasminogen activator inhibitor-1 gene (PAI-1-/- mice) are relatively protected from developing pulmonary fibrosis from bleomycin administration. We hypothesized that one of the protective mechanisms may be the ability of the plasminogen system to enhance hepatocyte growth factor (HGF) effects, which have been reported to be anti-fibrotic in the lung. HGF is known to be sequestered in tissues by binding to extracellular matrix components. Following bleomycin administration, we found that HGF protein levels were higher in bronchoalveolar lavage fluid from PAI-1-/- mice compared to wild-type (PAI-1+/+) mice. This increase could be suppressed by administering tranexamic acid, which inhibits plasmin activity. Conversely, intratracheal instillation of urokinase into bleomycin-injured PAI-1+/+ mice to activate plasminogen caused a significant increase in HGF within bronchoalveolar lavage and caused less collagen accumulation in the lungs. Administration of an anti-HGF neutralizing antibody markedly increased collagen accumulation in the lungs of bleomycin-injured PAI-1-/- mice. These results support the hypothesis that increasing the availability of HGF, possibly by enhancing its release from extracellular matrix by a plasmin-dependent mechanism, is an important means by which activation of the plasminogen system can limit pulmonary fibrosis.