Arsenic(III) fuels anoxygenic photosynthesis in hot spring biofilms from Mono Lake, California.

Phylogenetic analysis indicates that microbial arsenic metabolism is ancient and probably extends back to the primordial Earth. In microbial biofilms growing on the rock surfaces of anoxic brine pools fed by hot springs containing arsenite and sulfide at high concentrations, we discovered light-dependent oxidation of arsenite [As(III)] to arsenate [As(V)] occurring under anoxic conditions. The communities were composed primarily of Ectothiorhodospira-like purple bacteria or Oscillatoria-like cyanobacteria. A pure culture of a photosynthetic bacterium grew as a photoautotroph when As(III) was used as the sole photosynthetic electron donor. The strain contained genes encoding a putative As(V) reductase but no detectable homologs of the As(III) oxidase genes of aerobic chemolithotrophs, suggesting a reverse functionality for the reductase. Production of As(V) by anoxygenic photosynthesis probably opened niches for primordial Earth's first As(V)-respiring prokaryotes.

Nitrofen induces a redox-dependent apoptosis associated with increased p38 activity in P19 teratocarcinoma cells.

Nitrofen is a diphenyl ether herbicide that produces a spectrum of fetal abnormalities in rodents. To characterize the molecular mechanisms of nitrofen-mediated birth defects at the cellular level, we explored its effects on undifferentiated P19 teratocarcinoma cells. Nitrofen induces a time-dependent cell death of P19 cells that is associated with increases in TUNEL-positivity and caspase-3 cleavage suggesting that nitrofen induces P19 cell apoptosis. In addition, the increase in TUNEL-positive cells was inhibited with zVAD-fmk, suggesting that nitrofen induces a caspase-dependent apoptosis. Nitrofen treatment was associated with increased p38 MAP kinase activity, though pretreatment of cells with multiple p38 inhibitors did not affect nitrofen-mediated caspase-3 cleavage, suggesting caspase-3 cleavage is p38-independent. Nitrofen induced a dose-dependent increase in reactive oxygen species (ROS), which was accompanied by a decrease in the ratio of reduced/oxidized glutathione, indicating that nitrofen alters the cellular redox state of these cells. Furthermore, pretreatment of cells with N-acetyl cysteine gave a dose- and time-dependent reduction of caspase-3 cleavage, supporting the observations that caspase-3 cleavage is cell-redox-dependent. Therefore, nitrofen induces P19 cell apoptosis that is cell-redox-dependent and is associated with increases in p38 activity and ROS and may play a role in nitrofen-mediated birth defects.

A potentially powerful new tool for noninvasive diagnosis of cardiac abnormalities: the CUPID system for analysis of electrocardiograms in the frequency domain.

Clinical correlation of frequency-domain characteristics of electrocardiograms with specific disease entities of thousands of patients has produced a simple, noninvasive diagnostic system capable of detecting many cardiac abnormalities with specificity and sensitivity exceeding 90%. This system, a proprietary product called CUPID, is now undergoing clinical trials in Europe, South America, and the United States. The author discusses the physiologic basis of electrocardiography and the development of the CUPID system, and reviews the results of the trials that have been completed. The system appears to hold promise for fast, inexpensive, and accurate screening of patients for cardiac disease without somatic invasion.

Evaluation of the impact of employee ergonomics training in industry.

This study examined the effects of three different types of ergonomics training methods upon employee knowledge, attitude and behavior. Employees within intact processing lines (N = 104) were randomized into four groups, one group serving as a control group. Pre- and post-test measures were implemented. Results showed training to have a significant effect upon knowledge of ergonomics. No significant differences were noted among all four groups according to empowerment and human factors measures. Training had a significant impact upon employee's job satisfaction, and the recognition and reporting of health hazards associated with their jobs.

Basic biophysical principles of resurfacing of human skin by means of the carbon dioxide laser.

This discussion analyzes the biophysical effects of superpulsed, ultrapulsed, and swept-beam carbon dioxide lasers in the removal of the outer layers of skin for the purpose of facial resurfacing. It presents the differences in mode of operation among these systems, and their comparative advantages and disadvantages. The history of laser facial resurfacing, the characteristics of an ideal resurfacing laser, the importance of transverse electromagnetic mode, principles of minimization of thermal damage, the concept of ablation threshold, and the effect of pulse duration on thermal damage to adjacent tissue are discussed. The analysis is based upon some simplifying assumptions about the structure of epidermis and dermis, and the results are compared with those from empirical measurements, presenting a rational foundation for understanding the important phenomena of laser ablation of skin.

Photons, physiatrics, and physicians: a practical guide to understanding laser light interaction with living tissue, part I.

In the past 32 years, lasers have progressed from interesting curiosities to important instruments in medicine and surgery, with a wide variety of wavelengths and medical-surgical applications. Today's physician is faced with a bewildering array of laser types, each touted by its manufacturer as the ultimate surgical tool. This article sets forth in simple, understandable prose, the basic principles of the interaction of laser light with living tissue, so that the physician can decide which type of laser is best suited to a given application, without relying on the manufacturer's sales literature. The topics discussed are the nature of light; reflection, absorption, scattering, and attenuation in living tissue; physical processes by which laser light destroys tissue; relative importance of the three unique properties of laser light in surgery and therapy; temporal modes of lasers; means of delivering laser beams to their targets; and considerations in the selection of laser systems.

Effective development and utilization of self-learning modules.

This article provides guidelines to assist the nurse educator in designing self-learning modules for appropriate topics and learners, in creating the module, and in developing tools to evaluate the effectiveness of the module. By following the guidelines presented, the nurse educator can create cost-effective learning opportunities for professional nurses. Utilization of self-learning modules encourages nurses to be self-directed and allows the nurse educator to be the resource rather than the source of learning.

Breast implants under siege: an historical commentary.

Despite 3 decades of rapidly expanding application of polydimethylsiloxane as a relatively safe implantable biomaterial, the American public is being told by a vocal minority that its use in the breast implant may be dangerous. Most of the furor has been generated by consumer advocates with support of a handful of scientists who have expressed opinions, not well supported by facts, about the risks of these devices. These anxieties have been fueled in the public's mind by a media more interested in sensationalism than disciplined reporting. The controversy has complicated the regulatory process and has become politicized in the halls of State Legislatures and Congress. Remarkably, this controversy has not involved the many other biomedical applications of silicone. How has this controversy gathered momentum? What role has the government played and how have the professional, scientific, corporate, and patient communities responded to public concern? This discussion places the breast implant battle into an historical perspective.

Designing an internal organizational merger.

Healthcare managers face problems resulting from restructuring and downsizing activities meant to increase operational efficiency and reduce costs. Although keys to the success of multiorganizational mergers are well documented, directives for managing internal mergers are less clearly stated. The authors discuss a five-step plan designed to facilitate an internal merger through the strategic coordination of stakeholders.