Mental stress and trapezius muscle activation under psychomotor challenge: a focus on EMG gaps during computer work.

Momentary reductions in the electrical activity of working muscles (EMG gaps) contribute to the explanation for the relationship between psychosocial stress and musculoskeletal problems in computer work. EMG activity and gaps in the left and right trapezii were monitored in 23 participants under low and high mental workload (LMW and HMW) demands during computer data entry. Increases in EMG activity and decreases in EMG-gap frequencies in both left and right trapezius muscles were greater during HMW than LMW.

Determination of wavelength-specific UV protection factors of sunscreens in intact skin by EPR measurement of UV-induced reactive melanin radical.

There remains an unmet need for skin tissue-based assays for the measurement of the UVA protection and efficacy of sunscreens. Here we describe development of a novel electron paramagnetic resonance assay that uses the photogeneration of reactive melanin radical as a measure of UV light penetration to melanocytes in situ in skin. We have used areas of focal melanocytic hyperplasia in the skin of Monodelphis domestica to model the human nevus.

UV causation of melanoma in Xiphophorus is dominated by melanin photosensitized oxidant production.

Controversy continues both as to which wavelengths of sunlight cause melanoma and the mechanisms by which these different wavelengths act. Direct absorption of UVB by DNA is central in albino animal models, but melanin-pigmented models have shown major contributions by wavelengths longer than UVB that are thought to be mediated by photosensitized oxidant production. The only model for which the action spectrum of melanoma causation is known is a genetically melanoma-susceptible specific cross of Xiphophorus fish.

Blood, breath, fears redux, and panic attacks: comment on Roth, Wilhelm, and Pettit (2005).

This article discusses the hyperventilation theory (HVT) of panic attacks (PAs) proposed by R. Ley in the context of criticisms raised by W. T.

Comparison between ultraviolet-visible and near-infrared elastic scattering spectroscopy of chemically induced melanomas in an animal model.

The work reported compares elastic scattering spectroscopy (ESS) for diagnosis of pigmented skin lesions in two spectral regions: UV-visible and near infrared (NIR). Given the known strong absorption by melanin in the near-UV to mid-visible range of the spectrum, such a comparison can help determine the optimum wavelength range of ESS for diagnosis of pigmented skin lesions. For this purpose, four South American opossums are treated with dimethylbenz(a)anthracene on multiple dorsal sites to induce both malignant melanomas and benign pigmented lesions.

The conditioning of dyspneic suffocation fear. Effects of carbon dioxide concentration on behavioral freezing and analgesia.

Previous studies in our laboratory have shown that a single exposure to 100% carbon dioxide (CO2) can serve as an effective unconditioned stimulus (US) in a Pavlovian aversive-context conditioning paradigm in rats. Although the US exposure parameters employed in the initial studies were sufficient for producing a context-specific enhancement of behavioral freezing and analgesia, it had yet to be determined whether variations of these CO2 conditioning procedures would produce other conditioning effects. Thus, the purpose of the following experiment was to investigate the intensity of the US on the conditioned response (CR).

Standardized protocols for photocarcinogenesis safety testing.

Solar ultraviolet radiation (UVR) is recognized as a major cause of non-melanoma skin cancer in man. Skin cancer occurs most frequently in the most heavily exposed areas and correlates with degree of outdoor exposure. The incidence of skin cancer is also increased by contact with photosensitizing drugs and chemicals such as psoralens, coal tars and petroleum stocks.

A hyperventilation theory of job stress and musculoskeletal disorders.

Background: There is evidence of a link between job stress and upper extremity work-related musculoskeletal disorders. However, the biobehavioral mechanisms by which psychosocial stress factors contribute to the development of musculoskeletal disorders are uncertain.

Methods: Based on established principles of breathing and job stress and the relevant empirical literatures, a hyperventilation theory of job stress and work-related musculoskeletal disorders was developed.

Animal models of ultraviolet radiation (UVR)-induced cutaneous melanoma.

The incidence of cutaneous melanoma continues to increase in many parts of the world including the United States. The American Cancer Society predicts that there will be approximately 53,600 new cases of melanoma in the United States during 2002 and that there will be 7,400 deaths from melanoma during the same time period. Increased understanding of the underlying mechanisms and risk factors involved in the induction of this deadly disease will require the use of suitable animal models of melanoma.