The importance of including position and viewing direction when measuring and assessing the lighting conditions of office workers.

BACKGROUND: Light and alertness studies have applied different measurement methodologies to determine lighting conditions. However, it has been demonstrated that researchers rarely measure or describe the lighting conditions of their studies in sufficient detail to generalize conclusions or derive universal guidelines. OBJECTIVE: Part I of this paper summarizes the current measurement methodologies used in light and alertness studies to potentially identify methodological issues. Part II determines the differences in lighting conditions for different viewing directions within an office environment. METHODS: A literature review (part I) and both experimental studies and an observational study (part II) were undertaken in this study. RESULTS: Part I demonstrates that most light and alertness studies include photometric quantities; however, it is recommended that one should measure radiometric quantities as well. Further, the light measurements should be performed at the individual level. Part II demonstrates large differences in lighting conditions between viewing directions. For example, when looking toward the window, vertical illuminances were at least 12 times higher when compared to looking in the opposite direction. CONCLUSIONS: Our findings suggest that when analysing or designing an office environment, office workers' positions and viewing direction should be included in the determination of personal lighting conditions.

Recommendations for measuring non-image-forming effects of light: A practical method to apply on cognitive impaired and unaffected participants.

BACKGROUND: The non-image-forming effects of luminous radiation on people with intellectual disabilities or dementia received attention from researchers. Such studies, however, have generally been conducted using disparate methodologies which precludes generalization and reproducibility. OBJECTIVE: The aim of this study was to determine the practical applicability of measurement devices for studies investigating non-image-forming effects of luminous radiation, specifically for people with intellectual disabilities or dementia. METHODS: In three experiments, ten cognitive impaired people and thirty-nine unaffected subjects participated by wearing one or more portable devices. Six devices were assessed in total. Measurement data was accompanied with user experiences obtained from questionnaires, interviews and observations in order to assess the devices on practical and comfort issues. RESULTS: On average, the devices worn by the cognitive impaired subjects were not experienced as annoying or irritating. No significant differences are found between genders and for one of the portable devices significantly less annoyance was reported by the cognitive impaired participants compared to the unaffected group of participants. INNOVATIVE SOLUTION: The three phases of the research process in towards measuring personal luminous exposures are: selection of the most suitable portable device, application of the assessment method, and the application of the device in the (pilot) study. CONCLUSIONS: However, the findings of this study suggest that inaccuracies potentially caused by practical and comfort issues associated with the portable devices need to be considered.

Cutinase binding and activity at the triolein-water interface monitored by oil drop tensiometry.

Changes of the oil-water interfacial tension resulting from binding of Fusarium solani pisi cutinase and subsequent lipid hydrolysis were investigated using the oil drop technique. An ELISA was developed to determine the amount of cutinase bound to the triolein-water interface after biotinylation of the enzyme. Cutinase irreversibly adsorbs to a maximum value of about 2 mg/m2. A minimal specific activity of 110 mumol/min/mg was calculated for cutinase acting on a single oil droplet, which is close to the activity found for triglyceride emulsions. At a maximum surface load cutinase could generate one monolayer of fatty acid products per second at the interface. It was found that oleic acid rapidly dissolves into the oil phase under the conditions used. The interfacial tension measured reflects the adsorption of cutinase to the oil droplet and also responds to the fate of the hydrolysis products. A model is presented that describes the catalytic events at the oil-water interface during lipid hydrolysis.

MON-150, a versatile monoclonal antibody against involucrin: characterization and applications.

A monoclonal antibody, designated MON-150, was found serendipitously to react strongly with the granular layer of normal human epidermis and with the upper spinous layers of psoriatic epidermis. From analysis by flow cytometry of cultured human keratinocytes, it appeared that the percentage of MON-150-positive cells strongly increased when the cells reached confluence and the growth fraction declined. To identify the antigen recognized by MON-150, a lysate of human keratinocytes was subjected to affinity chromatography using a MON-150 Sepharose column. This yielded a single protein of approximately 350 kDa as measured on Superose 6 FPLC gel permeation chromatography using non-denaturing conditions. In Western blot analysis under denaturing and reducing conditions, a 140-kDa protein was detected. The subcellular localization and the molecular weight of the antigen recognized by MON-150 suggested that the antigen involved might be involucrin. This was confirmed using a commercial polyclonal antiserum against involucrin. We conclude that MON-150 is a new, versatile antibody against human involucrin.

A new photometric method for the quantitation of Fc receptors for murine IgG1 on human monocytes and cell lines.

We have previously shown a polymorphism of human Fc receptors for mouse IgG1 using an EA rosette technique in which human erythrocytes sensitized with a murine IgG1 monoclonal antibody against glycophorin A acted as indicator cells. We now describe a method to quantitate this EA rosetting using the pseudoperoxidase activity present in erythrocytes. This photometric assay allows the sensitive quantitative determination of Fc receptor expression on human monocytes and cell lines. Not only the human Fc receptor for murine IgG1 can be studied in this way, but the method can also be applied to other Fc receptors. An important factor in this type of rosette assay appears to be the amount of negative charge present on the surface of the indicator erythrocytes. Using alcian blue as a probe, we found that this negative charge is higher on human erythrocytes than on sheep erythrocytes, which may contribute to a better signal-to-noise ratio. The method described facilitates the characterization of Fc receptors and permits the rapid screening of monoclonal anti-Fc receptor antibodies.