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Biomedical subjects

C Franck

Publications and source records attributed to C Franck.

At least 19 recordsLinked to original sources
PubMed2006

The modern office environment desiccates the eyes?

Eye irritation is a common complaint in the office environment. The purpose of this overview is to merge knowledge within indoor air science, ophthalmology, and occupational health to promote understanding eye irritation symptomatology, the cause of which is still partly unknown. High periocular relative humidity appears to protect the pre-corneal tear film against desiccation and sensory irritating pollutants and reduces the development of eye irritation symptoms. This is particularly relevant for intensive computer work, where the pre-corneal tear film is altered resulting in dry spot formation and eye dryness, in addition to enhanced susceptibility towards sensory irritating pollutants. The workplace, thermal conditions, and work schedule (including breaks) should be planned in such a way to help maintain a normal eye blink frequency to minimize alterations of the pre-corneal tear film. The role of relative humidity on eye irritation symptoms should not be underestimated. Multiple short breaks are justified by the beneficial effect on the pre-corneal tear film. In addition, longer breaks in tasks, which require demanding visual work, should be considered. In addition, air temperature as well as certain alkene oxidation products by ozone may worsen eye irritation symptoms, but the latter factor may be smaller at higher relative humidity.

Air Pollutants, Occupational↗
PubMed2001

Comparative study of the O(2), CO(2) and temperature effect on respiration between "Conference" pear cell protoplasts in suspension and intact pears.

The influence of the O(2) and CO(2) concentration and the temperature on the O(2) uptake rate of cool-stored intact pears and pear cell protoplasts in suspension was compared. Protocols to isolate pear cell protoplasts from pear tissue and two methods to measure protoplast respiration have been developed. Modified Michaelis-Menten kinetics were applied to describe the effect of the O(2) and the CO(2) concentration on the O(2) uptake rate and temperature dependence was analysed with an Arrhenius equation. Both systems were described with a non-competitive type of CO(2) inhibition. Due to the inclusion of gas diffusion properties, the Michaelis-Menten constant for intact pears (2.5 mM) was significantly larger than the one for protoplasts in suspension (3 microM), which was in turn larger than the Michaelis-Menten constant obtained in mitochondrial respiration measurements described in the literature. It was calculated that only 3.6% of the total diffusion effect absorbed in the Michaelis-Menten constant for intact pears, could be attributed to intracellular gas diffusion. The number of cells per volume of tissue was counted microscopically to establish a relationship between the pear cell protoplast and intact pear O(2) uptake rate. A remarkable similarity was observed: values of 61.8 nmol kg(-1) s(-1) for protoplasts and 87.1 nmol kg(-1) s(-1) for intact pears were obtained. Also, the inhibitory effect of CO(2) on the respiration rate was almost identical for protoplasts and intact pears, suggesting that protoplast suspensions are useful for the study of other aspects of the respiration metabolism.

Carbon Dioxide↗
PubMed2000

Surprisingly short-ranged interactions in highly charged colloidal suspensions.

The interaction potential between colloidal particles in a suspension has been the topic of much research recently. Digital video microscopy techniques have come into wide use, as this method yields direct information about the structure of such systems. However, two main problems have plagued researchers working with this technique. First, what one sees through a microscope is actually a projection of a three-dimensional sample onto a two-dimensional image plane. Second, in order to achieve long-range interactions between particles, the ionicity of the surrounding medium must be as low as possible. In order to address the first problem, researchers have created quasi-two-dimensional samples by confining the system between two glass plates. However, this geometry makes it difficult to control the ionicity, and it also makes the analysis more difficult since one is dealing with an anisotropic system for which established theories of colloidal interactions formulated for the bulk do not apply. We have developed techniques to effectively address each of these two problems. Our sample cell is large enough to allow direct contact of the suspension with ion exchange resin, and allows one to make bulk measurements of the structure. In addition, we have developed techniques to handle the projection effects. We have used these methods to measure the radial distribution function of dilute suspensions of highly charged unconfined polystyrene microspheres in a density matched mixture of H2O and D2O. We found that the interaction potential between the colloidal particles was much shorter ranged than would be expected based on the Derjaguin-Landau-Verwey-Overbeek theory of colloidal interactions.

Journal Article↗
PubMed1993

Prevalence of objective eye manifestations in people working in office buildings with different prevalences of the sick building syndrome compared with the general population.

A cross-sectional clinical epidemiological study was carried out among 169 office workers in four Copenhagen town halls with different prevalences of the sick building syndrome. The results were compared with those in 112 subjects randomly selected from the general population. Biomicroscopic eye manifestations, such as premature break-up of the precorneal tear film, absence of foam at the inner eye canthus and epithelial damage of the bulbar conjunctiva, were investigated together with self-reported eye complaints. Although intercorrelated, the objective eye manifestations independently were statistically associated with self-reported eye complaints in office workers. The prevalence of the objective eye manifestations was significantly elevated in office workers compared with the general population and most pronounced for the buildings with a high prevalence of the sick building syndrome (P < 0.001). In the general population, subjects with a non-industrial occupation, including office workers, had a significantly higher prevalence of objective eye manifestations than those with an industrial occupation (P = 0.03), but the prevalence was still significantly lower than that among the office workers in buildings with a high prevalence of the sick building syndrome (P < 0.001). Since possible confounders were found not to explain the difference in prevalence of objective eye manifestations and complaints among the two populations, it is concluded that the office environment (buildings and/or type of office work) promotes these objective changes accompanied by self-reported complaints.

Adult↗
PubMed1993

Break-up time and lissamine green epithelial damage in 'office eye syndrome'. Six-month and one-year follow-up investigations.

Break-up time and lissamine green epithelial damage were re-investigated among 90 office workers after six months in 60 and after one year in 73. There was fairly good correlation with a rank correlation of about 0.40 between both break-up time and lissamine green staining epithelial damage at the initial investigation and at the two re-investigations. All correlations were found highly statistically significant. The results indicate that the manifestation of dry eyes in office workers to a great extent is chronic and without seasonal variation, at least as long as the subject remains in the office environment.

Air Pollutants, Occupational↗
PubMed1991

Fatty layer of the precorneal film in the 'office eye syndrome'.

The thickness of the fatty layer of the precorneal film was estimated by the semiquantitative inteference method in 70 office workers from two town halls in Copenhagen County and compared with that in 110 controls from the general population. There were significant correlations between use of eye make-up and a thin fatty layer (less than or equal to 50 nm, P = 0.023) and between investigation time before 12 h and a thick fatty layer (greater than or equal to 150 nm, P = 0.046). After correction for these confounders, the fatty layer was significantly reduced in the office population compared with the controls (P = 0.0032). Furthermore, absence of biomicroscopically dry eyes (expressed as a combination of premature break-up of the tear film and lissamine green-stained epithelial damage of the bulbar conjunctiva) was significantly correlated to a thick fatty layer (greater than or equal to 150 nm, P = 0.015), indicating that a thick fatty layer may protect the eyes against development of dry eyes. The results indicate that deficiency in available Meibomina oil is involved in the dry eye syndrome we earlier found to be associated with eye irritation in the office environment and termed the 'office eye syndrome'. Together with observation of foam in the eye canthus, estimation of break-up time, and examination for clusters of epithelial damage on the bulbar conjunctiva, measurement of the fatty layer appears to be an easy tool for diagnosing the 'office eye syndrome' or for differentiating this disorder from other conditions with complaints of dryness or irritation.

Adult↗
PubMed1991

Long-term changes in the outer part of the eye in welders. Prevalence of spheroid degeneration, pinguecula, pterygium, and corneal cicatrices.

Biomicroscopical examination of possible cumulative changes in the outer part of the eye in 217 male welders with variable welding exposure time showed conjunctival spheroid degeneration in 24% of the welders. The prevalence of changes was significantly increased in welders with the higher exposure time in an age-matched reduced material (98 x 2 eyes; respectively, over and under 40 h.y (number of daily hours of welding multiplied by number of years of welding), welders with stays abroad over one year being withdrawn. The prevalence was also increased in the latter group (41%, N = 40, against 21%, N = 177). Pinguecula was present in 57% of the welders, with a tendency towards larger area with increasing welding exposure. The frequency was increased as compared with that in a control material examined on a previous occasion (41%). Pterygium proper was found in only one subject, pseudopterygium in 5%. Corneal cicatrices were present in about one half of the subjects. The prevalence increased with increasing welding exposure (24% in subjects with short, 42% in those with long exposure; 98 x 2 eyes). Acute welding light keratopathy was experienced by 73%. The mean number of attacks in the 217 welders was 6.4. The frequency was highest in subjects with long welding exposure. The risk of chronic impairment of sight owing to cumulative welding light injuries is very little in the present material, since only 2% had spheroid degeneration on the cornea (only discrete, peripherally located); there was no preponderance of pterygium. On the other hand, the many foreign bodies on the cornea (cicatrices) constitute a risk that apparently does not decrease with increasing welding experience nor repeated attacks of welding light keratopathy.

Adolescent↗