Stochastic modeling of apoptosis tolerance distributions measured by multivariate flow analysis of human leukemia cells.

Background: Cytofluorometric analysis allows single-cell resolution of all-or-none programmed cell death (apoptosis) responses and permits direct measurement of cumulative frequency distributions (CFDs) of apoptosis sensitivity from which the median apoptosis tolerance can be estimated. Robust estimation of susceptibility to apoptosis within neoplastic cell populations provides a means of either accurately determining pharmacologically induced changes in apoptosis sensitivity or comparing cell population responses to different apoptosis inducers.

Methods: Experimentally determined CFDs for VP-16 (etoposide)-induced apoptosis were measured by phosphotidylserine surface expression and mitochondrial membrane potential dissipation (DeltaPsi(m)) in BV173 leukemia cells.

Parent education: an evaluation of STEP on abusive parents' perceptions and abuse potential.

Problem: To examine the effects of a structured, time-limited parent training group on abusive or potentially abusive parents.

Methods: A pretest-posttest control group design was used with consenting parents (N = 18) to examine the effects of Systematic Training for Effective Parenting (STEP) on abusive parents' perceptions of their children's behaviors and on the parents' potential to physically abuse. The Adlerian Parental Assessment of Child Behavior Scale and the Child Abuse Potential Inventory were used to measure treatment effects.

Quantitative antisense dose-response relationships: mathematical modeling of antisense action under steady-state conditions.

A quantitative theoretical analysis of antisense action is presented in which hyperbolic relationships between the logarithm of antisense oligodeoxynucleotide (AODN) ligand concentration, versus cognate messenger RNA (mRNA) and protein concentrations, are derived under conditions of steady state. This analysis incorporates a dual-compartment kinetic model of gene expression. The antisense dose-response functions yield an apparent equilibrium dissociation constant Kd (with the dimensions of concentration), which provides an index of binding affinity and AODN efficacy.

Gastrointestinal haemorrhage associated with free-base (crack) cocaine.

We report a case of a crack user presenting with chronic gastrointestinal haemorrhage due to deep gastric ulceration; the putative aetiology being predictable from this agent's pharmacology.

TCE degradation in a methanotrophic attached-film bioreactor.

Trichloroethene was degraded in expanded-bed bioreactors operated with mixed-culture methanotrophic attached films. Biomass concentrations of 8 to 75 g volatile solids (VS) per liter static bed (L(sb)) were observed. Batch TCE degradation rates at 35 degrees C followed the Michaelis-Menten model, and a maximum TCE degradation rate (q(max)) of 10.

Methanotrophic attached-film reactor development and biofilm characteristics.

The feasibility of using methanotrophs in an attached-film, fluidized-bed (MAFFB) reactor system has been under investigation since 1987. Mixed culture, methane-utilizing attached biofilms were developed on diatomaceous earth particles and on granular activated carbon. The required feed gases, methane and oxygen, were supplied to the attached biofilm in dissolved form using separate gas-liquid aeration columns.

Endothelial cells reestablish functional integrity after reversible permeabilization.

Permeabilization is an important tool in cell biology that allows manipulation of intracellular mechanisms by introduction of probes and regulatory molecules into the cell cytoplasm. We found that incubation of endothelial cells (ECs) with glass beads resulted in nonspecific permeabilization of human and bovine ECs without removal of the cells from monolayer culture. This poration of the plasma membrane allowed the introduction of macromolecules (dextrans less than or equal to 152 kd and immunoglobulins) as well as small, charged molecules (Lucifer Yellow).

Synthesis of platelet-activating factor by endothelial cells. The role of G proteins.

Production of the potent lipid autacoid, platelet-activating factor (PAF), is a stimulated response of the endothelium which has important physiologic consequences including mediating adherence of inflammatory cells to the endothelium. Consequently, an understanding of the mechanisms that regulate PAF synthesis by the endothelium is important. To this end, we investigated the role of G proteins as a component of the signal transduction pathway that couples hormonal stimuli to PAF production.

Kinetics of the human leucocyte Na(+)-H+ antiport in essential hypertension.

Many membrane abnormalities have been described in human essential hypertension that may lead to an increased intracellular Na+ content, an example being reduced Na+ efflux by the sodium pump. We have previously found increased Na(+)-H+ antiport activity in leucocytes of hypertensive subjects. In the present study we examined the kinetics of this pump in 16 hypertensive and 20 carefully matched normotensive subjects by loading cells to different intracellular pH levels (as measured by fluorimetry) using a double-ionophore technique.

The timing of the S phase and other nuclear events in yeast meiosis.

The length of the premeiotic S phase in individual cells of a homothallic strain of Saccharomyces cerevisiae was determined by pulse-labelling synchronously sporulating cultures with [3H]adenine and following changes in the frequency of cells in S by DNA-specific whole cell autoradiography. The average S phase was found to be at least 2-3 times as long as in mitotic diploids, and it was concluded that activation of replication origins in meiosis is considerably staggered. The timing of S in relation to other meiotic milestones was established by counting different nuclear morphologies visualised by DAPI-fluorescent staining.

Aspergilus flavus and aflatoxin in Iowa corn before harvest.

Aspergillus flavus and aflatoxin were detected in ears of Iowa corn on plants before harvest in 1975. Presence of the fungus was associated with kernel injury caused by the second generation European corn borer. Amounts of aflatoxin B1 in corn from a limited number of selected ears ranged from 1 part per billion to 1560 parts per billion with a mean of 430 parts per billion.

The self-association of L-alpha hydroxyacid oxidase.

As the published values for the molecular weight of L-alpha-hydroxyacid oxidase vary from 89 000 to 430 000, it is possible that such variations could be due to a concentration dependence of the molecular weight. The molecular weight of rat L-alpha-hydroxyacid oxidase was studied over a wide range of concentrations, using equilibrium sedimentation and gel exclusion chromatography. The partial specific volumes (0.

Curvularin from penicillium baradicum Baghdadi NRRL 3754, and biological effects.

Curvularin, a fungal metabolite similar in chemical structure to zearalenone, a potent estrogen, was tested for its estrogenic effects to gilts. No estrogenicity was observed to 60 kg gilts after feeding curvularin per os at a rate of 10 mg per day for 5 days. Curvularin was also nontoxic to mice and chick embryo.

Aflatoxin-producing strains of Aspergillus flavus detected by fluorescence of agar medium under ultraviolet light.

The fluorescence method of detecting aflatoxin-producing strains of Aspergillus flavus and related species utilizes the ultraviolet-induced fluorescence of aflatoxin produced in a modified Czapek's solution agar containing corn steep liquor, HgCl(2), and (NH(4))H(2)PO(4) instead of NaNO(3). The presence of aflatoxin is confirmed by thin-layer chromatography of CHCl(3) extracts of the fluorescing agar.

Mycotoxin-producing strains of Penicillium viridicatum: classification into subgroups.

Fifty-two isolates of Penicillium viridicatum Westling were divided into three groups based on ability to produce ochratoxin and/or citrinin, color, growth rate, type of growth, odor, and isolation source. Members of group I resemble one of the representative strains of P. viridicatum described in the literature; those belonging to group II differ from group I strains in several characteristics; group III is a heterogeneous series of highly variable isolates.