Sensitive detection of apoptogenic toxins in suspension cultures of rat and salmon hepatocytes

A number of algal toxins were tested for the ability to induce apoptosis (regulated cell death) in primary hepatocytes from salmon and rat. The tested toxins included the liver targeting substances microcystin-LR and nodularin, substances associated with the diarrhetic shellfish poison complex (okadaic acid, dinophysistoxin-1 and pectenotoxin-1) and calyculin A. All toxins induced apoptosis in both salmon and rat hepatocytes in less than 2 h. The apoptotic changes were evident both by electron and light microscopy and were counteracted by the caspase inhibitor ZVAD-fmk and by the Ca2+/calmodulin dependent kinase II inhibitor KN-93. The salmon hepatocytes were 10-20-fold more sensitive to okadaic acid and dinophysistoxin-1 (EC50=20 nM) than rat hepatocytes and other mammalian cell lines tested. An assay was devised using hepatocyte apoptosis as parameter for detection of algal toxins. This assay was at least as sensitive as HPLC determination for okadaic acid in mussel extracts. It also detected algal toxins which do not inhibit protein phosphatases, like pectenotoxin-1. Subapoptotic concentrations of the toxins inhibited hepatocyte aggregation. Using this parameter, less than 200 pg okadaic acid could be detected. In conclusion, salmon hepatocytes in suspension culture provide a rapid and sensitive system for detection of a broad range of apoptogenic toxins.     

Finite element modelling of welded aluminium members subjected to four-point bending

Finite element analyses are performed to predict the structural behaviour of welded and un-welded I-section aluminium members subjected to four-point bending. A modelling procedure using shell elements is established, where careful modelling of the inhomogeneous material properties due to welding is an important ingredient. A material model comprising anisotropic plasticity and ductile fracture is adopted. The yield function and work hardening parameters for the heat-affected zone, weld and base material are determined based on material tests and experimental data available in the literature. The numerical simulations comprise explicit analyses for a basic, relatively coarse mesh and implicit analyses for the same basic mesh and a refined mesh. Simulations are performed with perfect and imperfect geometries, since some beams fail by local buckling. The numerical results are compared with existing experimental data, and, in general, good agreement with the experimental results is obtained. However, the solutions are found to be mesh dependent for members failing by strain localisation and fracture in the tension flange.     

L- and T-type calcium currents differ in finch and rat ventricular cardiomyocytes

We compared L-type Ca current (ICaL) and T-type Ca current (ICaT) in finch and rat myocytes, using whole-cell patch clamp techniques. Cell capacitance averaged 50 +/- 4 pF in finch (n = 25) v 145 +/- 8 pF in rat (n = 38) cells, P < 0.001. In cells bathed in 1 mM Cao at 22 degrees C, peak ICaL amplitude, during a voltage clamp step (10 mM EGTA in pipette) from -45 mV to -5 mV, averaged 10.5 +/- 0.3 pA/pF in finch v 6.9 +/- 0.6 pA/pF, P < 0.001 in rat cells. ICaL inactivation kinetics were faster in finch (4.6 +/- 0.3 ms) than in rat (13.4 +/- 1.3 ms) cells. P < 0.001. ICaT was not detectable in rat cells (2 mM bathing [Ca]); but in finch cells, a large ICaT which averaged 6.8 +/- 1.4 pA/pF was activated at -30 mV and was relatively insensitive to nitrendipine (0.1 microM). The distinctive features of ICaL and ICaT in finch cells may have a role in the ability of the finch to achieve a very rapid heart rate. They may also facilitate excitation-Ca2+ release coupling in finch ventricular cells which are devoid of T tubules and have relatively few junctions between the sarcolemma and the sarcoplasmic reticulum.     

NIOSH research initiatives to prevent back injuries to nursing assistants, aides, and orderlies in nursing homes

Over the past 100 years, advances in nutrition, modern medicine, public health, and a multitude of public health improvements have increased the life expectancy of U.S. residents. The fact that Americans are living longer has resulted in extensive growth in our elderly population and a rapid employment growth that delivered about 2 million new jobs between 1980 and 1989 in the health care workforce. The Bureau of Labor Statistics Injury and Illness Data for nursing homes rose from 10.7 to 18.6 injuries or illnesses per 100 full-time workers between 1980 and 1992. The injury and illness rates among nursing home workers are partly due to the physical stress of providing round-the-clock assistance with the basic activities of daily living, such as getting in and out of a bed or chair, as well as bathing and toileting. The National Institute for Occupational Safety and Health (NIOSH) is conducting a series of research studies to identify strategies to reduce the risk of musculoskeletal injuries to workers in nursing homes. NIOSH has funded two laboratory evaluations of resident transferring methods and one field study in an actual nursing home. The purpose of this paper is to describe the key findings from past NIOSH research initiatives and to present an overview of future research.     

Biology of colorectal cancer in ulcerative colitis

Within the last decade, induction of ovulation with gonadotrophins, specially for patients with polycystic ovary syndrome, has been extensively revisited. On the basis of physiological concepts as the FSH threshold, the FSH window and the hypersensitivity to FSH of selected dominant follicle, news protocols have been described: step-up protocol, step-down, sequential protocol. In this article, their efficacy and safety are discussed. It is presumed that these new protocols would open a new way in the management of ovulation induction.