Murine defense mechanism against Candida albicans infection. I. Collaboration of cell-mediated and humoral immunities in protection against systemic C. albicans infection

Mice immunized with viable C. albicans cells demonstrated a high incidence of cell-mediated and a low incidence of humoral immune response. There was good agreement between the final survival rate of C. albicans infected mice and the rate of simultaneous cell-mediated and humoral immune response acquisition. Immunized mice with positive delayed hypersensitivity (DTH) against C. albicans crude antigen showed significant protection against intravenous challenge with C. albicans. Furthermore, the transfer of immunoglobulins from rabbit anti-C. albicans serum to DTH-positive mice enhanced protection, while it did not protect control mice against a subsequent challenge with C. albicans. These results suggest that cell-mediated immunity plays a major role and humoral immunity a side role in the defense mechanism(s) of C. albicans infected mice.     

The effect of apo E secretion on lipoprotein uptake in transfected cells.

To investigate the role of apolipoprotein E (apo E) secreted by peripheral tissues in local lipoprotein metabolism, we developed a cell strain that constitutively produced and secreted apo E. A fusion plasmid containing rat apo E genomic DNA under control of mouse metallothionein promotor was constructed and transfected into Chinese hamster ovary cells. A stable transformant designated CHO-MAEII constitutively secreted rat apo E mainly in the form of sialylated free protein. The secretion was further enhanced by metal induction up to 1 micrograms apo E/ml per 12 h. When incubated with 125I-labeled very low density lipoprotein (125I-VLDL) at 37 degrees C, CHO-MAEII took up and degraded 125I-VLDL with higher affinity than control cells. Furthermore, considerable amount of methylated 125I-VLDL was degraded by CHO-MAEII, while no methylated 125I-VLDL was degraded by control cells. No significant differences were found in the uptake of 125I-LDL. The data indicated that apo E molecules secreted by CHO-MAEII were transferred to 125-VLDL particles, which caused a higher affinity of these particles for LDL receptors on the cells. It is suggested that apo E secreted from peripheral tissues enhances the uptake of lipoproteins by themselves or by surrounding cells in the local environment which demand cholesterol and express LDL receptors. CHO-MAEII was a good model for these 'auto- or paracrine-like functions' of apo E.     

Effect of calcium on extraction of Z-band proteins from I-Z-I brushes of rabbit striated muscle.

1. When rabbit striated muscle I-Z-I brushes were subjected to eleven extractions with three different extracting solutions, relatively more amount of proteins was extracted in the presence of 1 nM CaCl2 than in the presence of 5 mM EDTA or 5 mM ethyleneglycol-bisp(beta-aminoethylether)-N,N,N1,N1-tetra-acetic acid (EGTA). Among proteins extracted in the presence of 1 mM CaCl2, the protein components with molecular weights of 85,000, 95,000 and 220,000 were included, whereas these were not extracted in the other two. 2. Co-electrophoreses of 220,000 dalton protein and myosin heavy chain showed that these two protein components were distinct from each other. 3. Roles of Ca2+ are discussed on disintegration processes of I-Z-I brushes in special reference to its co-operative action with calcium-activated factor enzyme.     

Titration of tetanus antitoxin by passive hemagglutination. II. Serological characteristics of antitoxin production in rabbits and monkeys.

1) Production of tetanus antitoxin in rabbits and monkeys was followed by passive hemagglutination (HA) and toxin-neutralization (TN) tests. The HA activity was observed in both IgM and IgG in both animal species. 2) In rabbits, IgM antitoxin was detected as early as in 7 days, reached the maximum titer in 10--14 days, and disappeared in 3 weeks after the primary immunization. Antitoxin of IgG class was detected in 10 days, and increased gradually. The ratio of HA/TN titers ("serum ratio") was high at an early stage of primary immunization and approached the unity in 3--4 weeks. Unlike the case of guinea pigs, IgM was found to contribute greatly to this high level of ratio. Besides, most rabbits produced IgG antitoxin of high ratios at early stages of immunization. 3) The immune response of monkeys showed a pattern very similar to that of rabbits except a few days' delay in the time course of antitoxin titers. No IgG antitoxin with a high serum ratio was demonstrated. Therefore, the high serum ratio of early sera could be accounted for mainly by IgM. 4) In response to the secondary immunization, no IgM antitoxin was detected in either animal species. 5) No definite correlation between serum ratio and avidity in terms of "dilution ratio" was demonstrated. However, both the dilution ratio and serum ratio were high at an early stage of immunization and gradually decreased, though the magnitudes of the ratios were variable depending on individual animals.     

Inhibition of the Growth Factor MDK/Midkine by a Novel Small Molecule Compound to Treat Non-Small Cell Lung Cancer

Midkine (MDK) is a heparin-binding growth factor that is highly expressed in many malignant tumors, including lung cancers. MDK activates the PI3K pathway and induces anti-apoptotic activity, in turn enhancing the survival of tumors. Therefore, the inhibition of MDK is considered a potential strategy for cancer therapy. In the present study, we demonstrate a novel small molecule compound (iMDK) that targets MDK. iMDK inhibited the cell growth of MDK-positive H441 lung adenocarcinoma cells that harbor an oncogenic KRAS mutation and H520 squamous cell lung cancer cells, both of which are types of untreatable lung cancer. However, iMDK did not reduce the cell viability of MDK-negative A549 lung adenocarcinoma cells or normal human lung fibroblast (NHLF) cells indicating its specificity. iMDK suppressed the endogenous expression of MDK but not that of other growth factors such as PTN or VEGF. iMDK suppressed the growth of H441 cells by inhibiting the PI3K pathway and inducing apoptosis. Systemic administration of iMDK significantly inhibited tumor growth in a xenograft mouse model in vivo. Inhibition of MDK with iMDK provides a potential therapeutic approach for the treatment of lung cancers that are driven by MDK.     

Double-layered collagen gel hemisphere for cell invasion assay: successful visualization and quantification of cell invasion activity

Although various methods for collagen gel-based cell invasion assays have been described, there continues to be a need for a simpler and more objective assay. Here, we describe an easy-to-prepare double-layered collagen gel hemisphere (DL-CGH) system that satisfies these requirements, and we demonstrate the advantages of this new system for visualizing cell movements during invasion. DL-CGH consists of a central core collagen layer surrounded by an outer cover collagen layer. A droplet of collagen I solution (containing cells to be examined) naturally forms a small hemisphere on the bottom of the culture dish. After this central core layer gels, a second droplet is placed atop the first gel, encapsulating it completely. The hemisphere is submerged in the medium and cultured. The invasive activity of cells that infiltrate from the inner to the outer layer can be evaluated optically. Using this in vitro system, we measured the inhibitory effect of E-cadherin expression on cancer cell invasion. DL-CGH also allowed visualization of interactions between invading cancer cells and the stroma. Cancer cells, which lack the proteases required for direct entrance into the three-dimensional collagen matrix, were seen to slip like amoebas through matrix gaps generated by the pericellular proteolytic activity of fibroblasts. [Supplementary materials are available for this article. Go to the publisher's online edition of Cell Communication and Adhesion for the following free supplemental resources: Movies 1-3; 4a and b].     

Lung volume and collapsibility of the passive pharynx in patients with sleep-disordered breathing.

Lung volume dependence of pharyngeal airway patency suggests involvement of lung volume in pathogenesis of obstructive sleep apnea. We examined the structural interaction between passive pharyngeal airway and lung volume independent of neuromuscular factors. Static mechanical properties of the passive pharynx were compared before and during lung inflation in eight anesthetized and paralyzed patients with sleep-disordered breathing. The respiratory system volume was increased by applying negative extrathoracic pressure, thereby leaving the transpharyngeal pressure unchanged. Application of -50-cmH(2)O negative extrathoracic pressure produced an increase in lung volume of 0.72 (0.63-0.91) liter [median (25-75 percentile)], resulting in a significant reduction of velopharyngeal closing pressure of 1.22 (0.14-2.03) cmH(2)O without significantly changing collapsibility of the oropharyngeal airway. Improvement of the velopharyngeal closing pressure was directly associated with body mass index. We conclude that increase in lung volume structurally improves velopharyngeal collapsibility particularly in obese patients with sleep-disordered breathing.     

Ultrastructural Investigation of Tension Wood Fibre in Fraxinus mandshurica Rupr. var. japonica Maxim.

The ultrastructure of the fibre wall in Fraxinus mandshuricaRupr. var. japonica Maxim. was investigated by electron microscopy.The trees had been inclined artificially at an angle of 30°to the vertical at the beginning of the initiation of cambialgrowth in early spring. The secondary walls of tension woodfibres were of the outer (S₁) layer and gelatinous (G) layertype. The microfibrils in the gelatinous (G) layer were orientedas a steep Z-helix relative to the fibre axis with a deviationthat ranged from 0° to 25° but was mainly between 5°and 10°. The cross-sectional surface of tension wood fibresrevealed the relatively strong attachment of the G-layer tothe S₁ layer. The G-layer stained weakly with potassium permanganate.The S₁ layer of tension wood fibres stained less strongly thanthat of the normal and opposite wood fibres. These results indicatethat the tension wood in F. mandshurica var. japonica is nottypical and is somewhat anomalous. The secondary walls of normaland opposite wood fibres were composed of two layers, S₁ andS₂, and lacked an S₃ layer. Microfibrils in the S₃ layer ofjuvenile stems were extremely variable in orientation and weresparsely distributed without forming a layer. By contrast, avery thin S₃ layer was present in the wood fibres of maturestems. The variations in the formation of the S₃ layer in thefibre walls were probably due to the differences in the cambialage of the stems of F. mandshurica Rupr. var. japonica.Copyright1995, 1999 Academic Press Fraxinus mandshurica Rupr. var. japonica Maxim., Japanese ash, tension wood, fibre wall, G-layer, microfibrillar orientation, normal and opposite wood, juvenile stem, field-emission scanning electron microscopy, low accelerating voltage