Analysis of a decreased Na+ conductance by tumor necrosis factor in identified neurons of Aplysia kurodai.

The ionic mechanisms of the effect of extracellularly ejected recombinant human tumor necrosis factor-alpha (rhTNF-alpha) on the membrane of identified neurons R9 and R10 of Aplysia kurodai was investigated with conventional voltage-clamp, micropressure ejection, and ion substitution techniques. Micropressure-ejected rhTNF caused a marked hyperpolarization in the unclamped neuron. Clamping the same neuron at it resting potential level (-60 mV) and reejecting rhTNF-alpha with the same dose produced a slow outward current [Io (TNF)] associated with a decrease in input membrane conductance. Io (TNF) was decreased by depolarization and increased by hyperpolarization. The extrapolated reversal potential of Io (TNF) was approximately +10 mV. Ion substitution and pharmacological experiments suggest that Io (TNF) in identified neurons R9 and R10 of A. kurodai is due to a decreased Na+ conductance but not due to an activation of the Na(+)-K+ pump. Our results demonstrate that the immunomodulator TNF can act directly on the nervous system as well as on the immune system.     

Climbing exercise increases bone mass and trabecular bone turnover through transient regulation of marrow osteogenic and osteoclastogenic potentials in mice.

To investigate the relationship between the effects of bone turnover and bone marrow cell development in bone cells, we developed a mouse voluntary climbing exercise model. Climbing exercise increased bone volume and transient osteogenic potential of bone marrow. This model would be suitable for investigating the mechanistic roles of mechanical loading. INTRODUCTION: The relationship between bone mass gain and local bone formation and resorption in mechanically loaded bone is not well understood. MATERIALS AND METHODS: Sixty-five C57BL/6J mice, 8 weeks of age, were assigned to five groups: a baseline control and two groups each of ground control and climbing exercise mice for 2 and 4 weeks. Mice were housed in a 100-cm tower and had to climb toward a bottle placed at the top to drink water. RESULTS: Compared with the ground control, bone mineral density of the left femur increased in the climbing mice at 4 weeks. At 2 and 4 weeks, bone formation rate (BFR/BS) of periosteal surface, the cross-sectional area, and moment of inertia were increased in the climbing mice, whereas BFR/BS and eroded surface (ES/BS) of endosteal surface did not differ. The trabecular bone volume (BV/TV) of the proximal tibia increased in climbing mice, and osteoclast surface (Oc.S/BS) and osteoclast number decreased at 2 weeks. At 4 weeks, there were increases in BV/TV and parameters of bone formation, including mineralized surface, mineral apposition rate, and bone formation rate. In marrow cell cultures from the tibia, the number of alkaline phosphatase+ colony forming units-fibroblastic and the area of mineralized nodule formation in climbing mice were increased, and the number of osteoclast-like TRACP+ multinucleated cells was lower at 2 weeks. At 4 weeks, these parameters recovered to the levels of the ground controls. CONCLUSION: Our results indicate that climbing increased trabecular bone volume and reduced bone resorption, with a subsequent increase in bone formation. Intermittent climbing downregulates marrow osteoclastogenic cells and upregulates osteogenic cells initially, but further exercise seemed to desensitize them. Cortical envelopes were enlarged earlier, but the response seems to differ from trabecular bone.     

An acetylcholine-induced potassium current in tail sensory neurons in the pleural ganglion of Aplysia

Acetylcholine (ACh) induces a hyperpolarization during current clamp and an outward current during voltage clamp in tail sensory neurons of Aplysia kurodai. This response was proved to be produced by a specific increase in membrane permeability toward potassium ions, the cholinergic antagonists, d-tubocurarine chloride (d-TC), and atropine mildly reduced the ACh response, while tetraethylammonium (TEA) most effectively blocked this response. These findings provide evidence that tail sensory neurons have the inhibitory ACh receptor in addition to the known receptors for serotonin (5-HT), small cardioactive peptide B (SCPB), and neuropeptide Phe-Met-Arg-Phe-NH2 (FMRFamide).     

A CASE OF GASTRIC CARCINOMA WITH MASSIVE EOSINOPHILS

This report describes a 67-year-old male with inoperable gastric cancer accompanied by marked tissue and peripheral eosinophilia without evidence of allergic disorders or parasitic infestation. Autopsy revealed an advanced gastric cancer of scirrhous type with metastases to pancreas, bone marrow, ileum, lungs, and lymph nodes. Excessive numbers of mature eosinophils were present in univolved bone marrow, liver and spleen as well as among the signet ring cell component of the cancer in either primary or metastatic sites. The primary cancer also possessed a component of tubular adenocarcinoma which was associated with only a few eosinophils. Hence, we speculate that an eosinophil mobilizing (chemotactic and/or proliferating) factor (s) was produced by the signet ring cancer cells.     

The effect of calcium ion concentration on osteoblast viability, proliferation and differentiation in monolayer and 3D culture

Our research group aims to develop an osteochondral composite using type II collagen gel with hydroxyapatite (HAp) deposited on one side. Soaking gels in Ca2+ and phosphate solution is indispensable to HAp deposition, so relationships between cell behavior and Ca2+ concentration were examined in two- and three-dimensional cultures. The present results indicate that 2-4 mM Ca2+ is suitable for proliferation and survival of osteoblasts, whereas slightly higher concentrations (6-8 mM) favor osteoblast differentiation and matrix mineralization in both 2- and 3-dimensional cultures. Higher concentrations (>10 mM) are cytotoxic. Purely from the perspective of calcium deposition, higher concentrations lead to increased accumulation of Ca2+. Culturing cells in phosphate-containing gel in media with Ca2+ also leads to time-dependent formation of HAp in the gel. Considering the viability of embedded cells, culturing scaffolds in media with Ca2+ concentrations around 5mM is useful for both HAp deposition and osteoblast behavior.     

Effects of exogenous interferon on L cells persistently infected with Sendai virus

Summary A carrier culture of L cells persistently infected with Sendai virus (steady state) designated as L-Sendai_ts cells was established with a temperature-sensitive strain of the virus. When interferon was added to culture fluids from the start of the cultures at permissive (35° C) or non-permissive temperature (38° C), cell-associated infectivity was unaffected at 35° C, while it was unexpectedly enhanced at 38° C, although the cell-associated infectivity was titrated after further incubation at 32° C for 2 days. The titer of cell-associated infectivity was increased by subculturing in the continuous presence of interferon at 38° C. The effect of interferon on the paradoxical enhancement of cell-associated infectivity was shown to be dose dependent. When L-Sendai_ts cells were successively subcultured 6 times at 38° C in the continuous presence or absence of interferon, more than 95 per cent of the cells contained a detectable amount of nucleocapsid (NP) antigen in the presence of interferon, whereas the antigen could be detected in only 30–40 per cent of the cells subcultured in the absence of interferon. Only when the cells subcultured at 38° C in the presence of interferon were transferred to permissive temperature, could the distinct hemadsorbing and cell-associated hemagglutinating activities and the release of virus particles, as measured by hemagglutinating activity in the culture fluids, be detected. Cells subcultured in the presence of interferon accumulated more virus polypeptides than in the absence of interferon. Accumulation of virus specific RNA in the cells subcultured in the presence of interferon was about twice as much as that in the absence of interferon. Larger sized RNA (probably 50S) was the major species and two smaller RNAs could be detected in both the treated and untreated cells.When L-Sendai_ts cells were cultured at 38° C in the presence of interferon, their multiplication was clearly inhibited. However, the cells which were subcultured twice at 38° C in the continouos presence of interferon acquired resistance to the anti-cell proliferative action of interferon. Interestingly, the conversion of the sensitive state to resistant state of the cells was reversible.With 3 Figures     

Antiphospholipid antibodies (APA) and recurrent pregnancy loss: treating a unique APA positive population

Dear Sir, We read the recent article by Franklin and Kutteh (2002), concerningthe pregnancy outcomes of recurrent pregnancy loss (RPL) patientswho had normal obstetrical evaluations with the exception ofpositive antiphospholipid antibodies (aPL) findings. In theirreport distinctions were made between two groups of aPL positiveRPL patients with reference to their aPL specificities. Group1 patients had ‘the common’ aPL, anticardiolipin(aCL), or antiphosphatidylserine antibodies (aPS) and/or a lupusanticoagulant (LAC). For comparisons,