Double minutes and other chromosomal aberrations in two malignant cell lines of the German cockroach Blattella germanica

Structural anomalies of mitotic chromosomes from two tumorigenic cell lines of the German cockroach (Blattella germanica) is described. Aberrations, such as unpairable marker chromosomes, double minutes, di- and tricentrics, ring chromosomes, tri- and quadriradials, and chromosome and chromatid gaps and breaks, were observed in varying proportions. This study reports that the double minute chromosomes (DMs) are associated with insect tumor cells, similar to the findings in both murine and human tumor cells.     

Influence of volume dilution, lactate, phosphate, and calcium on mitochondrial functions.

Oxidative phosphorylation of isolated canine myocardial mitochondria has been evaluated after exposure to different concentrations of phosphate (5--50 mM), lactate ion in excess (5--40 mM, pH 7.4), calcium (50--270 nmol/mg protein), to lactic acidosis (pH 6.3), and to mitochondrial protein dilution (in vitro volume expansion) for 10 min to 8 h. The influence of phosphate and lactate ion addition, lactic acidosis, and in vitro volume expansion on mitochondrial function were studied in the isolation medium (0.18 M KCl, 0.5% BSA (bovine serum albumin), with or without Tris-EDTA, pH 7.4) prior to evaluation of mitochondrial function in the assay medium (0.25 M sucrose, 10 mM Tris-HCl, and 10 mM inorganic phosphate, pH 7.4). The effect of calcium addition was assessed in the assay medium. The results of these studies demonstrate that each of these interventions detrimentally alters mitochondrial oxidative phosphorylative ability. The most severe mitochondrial functional impairment resulted from phosphate or calcium addition. The detrimental effect of phosphate and in vitro volume expansion was partially corrected by the addition of cytochrome c.     

Induction of delayed-type hypersensitivity responses to PPD: dendritic cells in synergy with 5-hydroxytryptamine can substitute for macrophages.

We describe the use of 5-hydroxytryptamine (5HT) as an adjuvant in the induction of the delayed-type hypersensitivity (DTH) response to purified protein derivative (PPD). Based upon our previous studies with antigen-pulsed macrophages (M phi), we have shown that both the Day 2 early (2 hr) reaction and the Day 3 (24 hr) reaction are augmented if 5HT is incorporated into the priming injection. Furthermore, we have confirmed that in contrast to M phi, antigen-pulsed dendritic cells (DC) fail to prime the early (2 hr) component of DTH. However, DC do prime the early response if injected along with 5HT. A peripheral 5HT antagonist, ICS 205-930, inhibits both the M phi-mediated and the 5HT/DC-primed reactions. These findings support the hypothesis that DTH reactions require a cascade of both inflammatory and immunological signals, and that in mice vascular permeability mediated via 5HT is important in the early phase of the reaction.     

Substitution of carbonate buffer by water for IgG immobilization in enzyme linked immunosorbent assay

The first step of enzyme linked immunosorbent assay (ELISA), namely, adsorption of antigen or antibody to the plastic microtiter well plate, was studied as a function of insolubility of IgG in water. Immobilization efficiency was assessed in terms of number of wells coated per milliliter of primary antiserum. We have compared different coating/immobilization protocols, i.e., direct and indirect immobilization of primary antibody to the plastic microtiter well plate using carbonate buffer and phosphate buffer with glutaraldehyde. We have observed efficient coating when the immobilization of primary antibody through an immunobridge technique was performed, where water was used as a coating medium. It gave a higher number of wells coated per milliliter of anti-serum (primary or secondary) than other compared coating protocols and it allowed the use of serum (non-immune) and anti-serum (primary and secondary antibody) dilutions, avoiding the need for gamma-globulin purification from normal and immunized serum.     

Ultrastructural changes in the cerebellum of nursling rats given corynetoxin, the aetiological agent of annual ryegrass toxicity

Nursling rats were given a lethal dose of corynetoxin and the sequential morphological alterations in the cerebellum were examined at daily intervals up to 3 days post-inoculation. Ultrastructural changes were those of cerebral vascular damage, which was usually focal in affected endothelial cells, and resulted in vascular stasis or thrombosis. These changes ultimately constituted a failure of perfusion in focal areas of brain parenchyma supplied by these vessels, resulting in necrosis.     

Dynamic pressure transmission through agarose gels

In biomedical research, agarose gel is widely used in tissue culture systems because it permits growing cells and tissues in a three-dimensional suspension. This is especially important in the application of tissue engineering concepts to cartilage repair because it supports the cartilage phenotype. Mechanical loading, especially compression, plays a fundamental role in the development and repair of cartilage. It would be advantageous to develop a system where cells and tissues could be subjected to compression so that their responses can be studied. There is currently no information on the pressure response of agarose gel when pressure is applied to the gas phase of a culture system. To understand the transmission of pressure through the gel, we set up an apparatus that would mimic an agarose suspension tissue culture system. This consisted of a sealed metal cylinder containing air as well as a layer of agarose submerged in culture medium. Pressure responses were recorded in the air, fluid, gel center, and gel periphery using various frequencies, pressures, gel volumes, and viscosities. Regression analyses show an almost perfect linear relation between gas and gel pressures (r(2) = 0.99987, p < 0.0001, f(x) = 0.9982 x - 0.0286). The pressure transmission was complete and immediate, throughout the range of the applied pressures, frequencies, volumes, and viscosities tested. Applying dynamic pressure to the gas phase results in reproducible pressure in the agarose and, therefore, validates the use of agarose tissue culture systems in studies employing dynamic pressurization in cartilage tissue engineering.