Majority of Actinomadura clinical isolates from sputa or bronchoalveolar lavage fluid in Japan belongs to the cluster of Actinomadura cremea and Actinomadura nitritigenes, and the description of Actinomadura chibensis sp. nov

In Japan during 1996-2004, 21 actinomycete strains that have madurose as the diagnostic cell-wall sugar and show true branching in their substrate and aerial mycelia were isolated from sputa or bronchoalveolar lavage (BAL) fluid of patients with pulmonary infections or who were suspected of having related infections. Chemotaxonomic studies showed that all the isolates belong to the genus Actinomadura. Among them, six and seven strains were classified respectively into clusters of Actinomadura nitritigenes and Actinomadura cremea based on 16S rDNA analyses because their 16S rDNA similarities to those respective species were greater than 99.5%. To our knowledge, this is first report that strains of above two species were isolated from clinical specimens. Neither Actinomadura madurae nor Actinomadura pelletieri strain was isolated, and one new species, Actinomadura chibensis, was proposed; the remaining seven strains were not assigned into any known species, suggesting the presence of another new Actinomadura species.     

Mechanism of plasma glutathione peroxidase production in bovine adipocytes

CD97, an epidermal growth factor (EGF)-TM7 receptor, is not restricted to hematopoetic and carcinoma cells but is also found on smooth muscle cells (SMC). We have examined its location and biochemical structure in various normal and tumorigenic SMC-containing tissues. SMC of the urinary bladder, lung bronchi and bronchioles, myometrium, and gastrointestinal tract were immunohistologically stained by using monoclonal antibodies (mabs) to the CD97 stalk region (CD97^stalk). Mabs directed against an N-glycosylation-dependent epitope within the EGF-domains (CD97^EGF) did not bind to normal SMC. Vascular SMC, which was also CD97^EGF-negative, showed further CD97 heterogeneity. Only a few, if any, SMC from the aorta or elastic arteries of the systemic circulation were positive for CD97 mRNA and therefore also for CD97^stalk. CD97^stalk-positive SMC were slightly more numerous in muscular and peripheral arteries. In contrast, most venous SMC expressed CD97^stalk. A comparison with other SMC molecules revealed a similar but not identical staining pattern for CD97^stalk and desmin. Further CD97 heterogeneity was observed during SMC transformation. All leiomyomas (n=5) and nine out of 21 leiomyosarcomas were positive for both CD97^stalk and CD97^EGF. As expected, CD97^EGF-positive SMC tumors expressed partly N-glycosylated CD97. Seven out of 21 leiomyosarcomas were completely devoid of CD97. Thus, CD97 showed variable expression in vascular and biochemical modification in tumorigenic SMC, suggesting that the function of the molecule is specific for the SMC subtype. This study was supported by a joint grant from the German Research Council (DFG; project AU 132/3-1) and by the Interdisziplinary Center of Clinical Research (IZKF) Leipzig at the Faculty of Medicine, University of Leipzig (project D6). E. Wandel is a fellow of the IZKF.     

Queen-worker differences in spermatheca reservoir of phylogenetically basal ants

Ant queens mate when young and store sperm in their spermatheca to fertilize eggs for several years until their death. In contrast, workers in most species never mate. We have compared the histological organization of spermathecae in 25 poneromorph species exhibiting various degrees of queen-worker dimorphism. The spermathecae of both castes in all species are similar in having a reservoir connected by a sperm duct to the ovary, and a paired gland opening into this duct. The reservoir of queens typically has a columnar epithelium in the hilar region (near the opening of the sperm duct), whereas the epithelium in the distal region is cuboidal. Abundant mitochondria together with apical microvilli and basal invaginations indicate an osmoregulatory function. In contrast, the reservoir epithelium of workers is flattened throughout and lacks these transport characteristics. This single difference shows the importance of a columnar epithelium in the reservoir for sperm storage. However, our data have not revealed inter-specific variations in the development of the hilar region linked with higher fecundity. We have found no consistent differences in associated structures, such as the spermatheca gland or sperm ducts, or in the musculature between queens and workers.This work was funded by IWT, FWO, KULeuven OT and JSPS.     

Monoclonal antibody A7 coupled to magnetic particles as a contrast enhancing agent for magnetic resonance imaging of human colorectal carcinoma

Background: Local recurrence, the most frequent pattern of recurrence of rectal carcinoma, is almost always fatal. The difficulty of diagnosing local recurrence contributes importantly to the poor prognosis. Methods: We coupled monoclonal antibody (Mab) A7, which reacts specifically with human colorectal carcinoma, to ferromagnetic lignosite (FML) particles to distinguish rectal carcinoma from other tissues by magnetic resonance (MR) imaging. We examined retention of immunoreactivity by the A7-FML complexes in vitro, and also their distribution in vivo according to radiolabeling and MR imaging when injected into nude mice bearing human colorectal carcinoma xenografts. Results: A7-FML retained binding activity nearly identical to that of Mab A7. Significantly more ¹²⁵I-labeled A7-FML accumulated in engrafted tumors than did ¹²⁵I-labeled normal mouse IgG-FML complexes (P<0.05). A7-FML disappeared rapidly from the blood. Normal tissues accumulated less ¹²⁵I-labeled A7-FML than tumors; this accumulation decreased linearly with time. In MR imaging, signal intensity was reduced in the tumor by the injection of A7-FML. Conclusions: A7-FML is potentially useful as a MR contrast enhancing agent for human colorectal carcinoma xenografts implanted subcutaneously.     

A structured erythropoiesis model with nonlinear cell maturation velocity and hormone decay rate

We develop a quasilinear structured model that describes the regulation of erythropoiesis, the process in which red blood cells are developed. In our model, the maturation velocity of precursor cells is assumed to be a function of the erythropoietin hormone, and the decay rate of this hormone is assumed to be a function of the number of precursor cells, unlike other models which assume these parameters to be constants. Existence-uniqueness results are established and convergence of a finite difference approximation to the unique solution of the model is obtained. The finite difference scheme is then used to investigate the effects of these nonlinear parameters on the model dynamics. Our results show that a velocity of precursor cells maturation rate which is an increasing function of the hormone level and a decay rate of the hormone which is an increasing function of the number of precursor cells have a stabilizing effect on the dynamics of the model. While assuming that one parameter is a function and letting the other be a constant stabilizes the oscillations in the mature cells level, the effect is more significant when both parameters are taken to be functions. A study of robustness with respect to the forms of these functions and parameter sensitivity is also carried out.     

Ferric ions involved in the flower color development of the Himalayan blue poppy, Meconopsis grandis

The Himalayan blue poppy, Meconopsis grandis, has sky blue-colored petals, although the anthocyanidin nucleus of the petal pigment is cyanidin. The blue color development in this blue poppy involving ferric ions was therefore studied. We analyzed the vacuolar pH, and the organic and inorganic components of the colored cells. A direct measurement by a proton-selective microelectrode revealed that the vacuolar pH value was 4.8. The concentrations of the total anthocyanins in the colored cells were around 5mM, and ca. three times more concentrated flavonols were detected. Fe was detected by atomic analysis of the colored cells, and the ratio of Fe to anthocyanins was ca. 0.8 eq. By mixing the anthocyanin, flavonol and metal ion components in a buffered aq. solution at pH 5.0, we were able to reproduce the same blue color; the visible absorption spectrum and CD were identical to those in the petals, with Fe(3+), Mg(2+) and flavonol being essential for the blue color. The blue pigment in Meconopsis should be a new type of metal complex pigment that is different from a stoichiometric supramolecular pigment such as commelinin or protocyanin.     

Cytotoxic Alangium alkaloids from Alangium longiflorum

Seven alkaloids (1-7) were isolated from the stem bark of Alangium longiflorum. Compound 1, (-)-10-O-demethylisocephaeline, was isolated for the first time as a naturally occurring product from a plant source. All structures were elucidated by detailed spectroscopic analysis. Biological evaluation showed that 2, 10-O-demethylcephaeline, exhibited potent cytotoxic activity against human lung carcinoma (A549) and breast adenocarcinoma (MCF-7) with ED(50) values of 0.013 and 0.062 microM, respectively. The stereoisomer 1 was less potent than 2, and related compounds with different hydroxy/methoxy substitution patterns were also less potent or inactive. Thus, compound 2 merits attention as a cytotoxic lead for further study.     

Chara myosin and the energy of cytoplasmic streaming

Recently, it was found that myosin generating very fast cytoplasmic streaming in Chara corallina has very high ATPase activity. To estimate the energy consumed by this myosin, its concentration in the internodal cells of C. corallina was determined by quantitative immunoblot. It was found that the concentration of Chara myosin was considerably high (200 nM) and the amount of ATP consumed by this myosin would exceed that supplied by dark respiration if all myosin molecules were fully activated by the interaction with actin. These results and model calculations suggested that the energy required to generate cytoplasmic streaming is very small and only one-hundredth of the existing myosin is enough to maintain the force for the streaming in the Chara cell.     

Contribution of indirect action to radiation-induced mammalian cell inactivation: dependence on photon energy and heavy-ion LET

The contribution of indirect action mediated by OH radicals to cell inactivation by ionizing radiations was evaluated for photons over the energy range from 12.4 keV to 1.25 MeV and for heavy ions over the linear energy transfer (LET) range from 20 keV/microm to 440 keV/microm by applying competition kinetics analysis using the OH radical scavenger DMSO. The maximum level of protection provided by DMSO (the protectable fraction) decreased with decreasing photon energy down to 63% at 12.4 keV. For heavy ions, a protectable fraction of 65% was found for an LET of around 200 keV/microm; above that LET, the value stayed the same. The reaction rate of OH radicals with intracellular molecules responsible for cell inactivation was nearly constant for photon inactivation, while for the heavy ions, the rate increased with increasing LET, suggesting a reaction with the densely produced OH radicals by high-LET ions. Using the protectable fraction, the cell killing was separated into two components, one due to indirect action and the other due to direct action. The inactivation efficiency for indirect action was greater than that for direct action over the photon energy range and the ion LET range tested. A significant contribution of direct action was also found for the increased RBE in the low photon energy region.