Computer model to investigate the effect of eye movements on retinal heating during long-duration fixation on a laser source

A computer simulation called RHME (Retinal Heating in Moving Eye) is developed to simulate the heating pattern that occurs in the retina during a long-duration exposure to a continuous wave laser beam. The simulation takes into account eye movements that occur during a deliberate fixation. Due to the rapid (millisecond) thermal time scale for heating and cooling, only the area of the retina directly exposed to the laser sustains an increased temperature. Once the laser spot is removed from a particular location of the retina (because of eye movements) that location quickly cools. Points of the retina will therefore have a complex thermal history during a long-duration exposure. Simulation results for a minimal retinal spot size indicate that subjects staring at a helium-neon laser (lambda=632.8 nm) beam producing the small-source maximum permissible exposure (MPE) level corneal irradiance of 1 mW cm(-2) (>10-s exposure) will experience a maximum although transient temperature increase in the retina of less than 2 degrees C during a 50-s fixation trial. The large increase in the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and ANSI Z136.1 safety limits for a long-duration small-source exposure to visible continuous wave lasers that was adopted in 2000 therefore appears appropriate.     

Clara cell secretory protein deficiency alters clara cell secretory apparatus and the protein composition of airway lining fluid

Clara cells represent the predominant secretory cell within distal conducting airways of mammals and exhibit functional alterations with chronic lung disease. We previously demonstrated that Clara cell secretory protein (CCSP) deficiency results in enhanced susceptibility to environmental agents. The present study was undertaken to define changes in Clara cell secretory function associated with CCSP deficiency in knockout mice. Comparative morphometry of Clara cell ultrastructure revealed dramatic alterations in secretory apparatus between wild-type (WT) and CCSP knockout (CCSP-/-) mice. Secretory granules, which occupy greater than 2% of Clara cell cytoplasmic volume in WT mice, were completely absent among Clara cells of CCSP-/- mice. Moreover, Clara cells of CCSP-/- mice exhibited a > 95% reduction in rough endoplasmic reticulum and alterations to Golgi apparatus, relative to WT controls. Ultrastructural perturbations to Clara cells were associated with altered protein composition of airway lining fluid as revealed by two-dimensional gel analysis of bronchoalveolar lavage proteins, but were not associated with altered abundance or secretion of CC26, another Clara cell secretory protein. We conclude that CCSP is required for the appearance of Clara cell secretory granules and that functional changes to Clara cells that result from CCSP deficiency lead to alterations in the composition of epithelial lining fluid.     

Butyrate increases production of human chimeric IgG in CHO-K1 cells whilst maintaining function and glycoform profile

The influence of sodium butyrate on the production and glycosylation of recombinant mouse/human chimeric antibody by transfected CHO-K1 cells was investigated. We selected cells expressing 'wild-type' antibody with a human IgG3 heavy chain and a mutant of this molecule in which Phe 243 is replaced by Ala. These proteins have previously been shown to exhibit very different glycoform profiles with the mutant IgG being comprised of glycoforms having a high galactose and sialic acid content. Cell culture with 0-5 mM butyrate was shown to effect a 2-4-fold increase in antibody production whilst the induction of apoptosis was observed in a dose-dependent manner. The optimal butyrate concentration was observed to be 2 mM. The glycoform profile of each antibody produced in the presence of butyrate was analyzed by HPAEC-PAD and shown to be unchanged, relative to that produced in the absence of butyrate. Biological activity was evaluated by the ability of the antibodies to trigger superoxide generation, through Fc gamma RI, and shown to be independent of production in the presence or absence of butyrate. A similar increase in production was observed for a high antibody-producing cell line when expanded in a hollow fibre bioreactor under low-serum conditions (1%). These results demonstrated that butyrate is of value for increasing the productivity of CHO-K1 for recombinant IgG and does not compromise either glycosylation or biological activity.     

In vitro effects of drugs on production of mucins in rabbit tracheal epithelial cells expressing mucin gene

Rabbit tracheal epithelial cells, cultured on collagen-coated dishes in serumfree and hormone-supplemented medium, were found to incorporate [³H]glucosamine into high-molecular-weight components that were secreted in the medium. The chemical analysis of the secreted products resulted in a profile that resembled that of mucous glycoproteins (mucins). When examined by dot blot analysis, the total RNA isolated from these cells hybridized to an antisense 30-mer oligonucleotide corresponding to a rat intestine mucin peptide sequence, indicating that mucin gene was expressed in these cell lines. Lung and liver tissues of rabbit did not express this gene. Transmission electron microscopy exhibited secretory granules in these cells. The incorporation of [³H]glucosamine into mucins was inhibited by three aryl-N-acetyl-galactosaminides and a chemical carcinogen,N-nitroso-N-ethyl urea, whereas 5-azacytidine enhanced the proliferation of cells as well as the radiolabeling of mucins. Parasympathetic agent (pilocarpine), cholinergic antagonist (atropine), and-adrenergic agonist (isoproterenol) alone have little effect on the secretion of mucins. The cholinergic agonist, methacholine, was found to increase the production of mucins and addition of atropine to the medium before methacholine blocked this stimulation. Histamine was found to stimulate mucin production in these cells.The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense.     

Effect of sunlight exposure on circulating 1,25-dihydroxyvitamin D in hemodialyzed patients and of exogenous parathyroid hormone in anephric patients

Sunshine exposure increased the serum concentration of 25-hydroxyvitamin D (25-OHD) in 9 hemodialyzed patients. Mean 1,25-dihydroxyvitamin D (1,25-(OH)2D) was unchanged, but in two patients with low initial 25-OHD values this increase was accompanied by a rise in circulating 1,25-(OH)2D, although not to normal levels. One hemodialyzed patient developed liver insufficiency with a resultant reduction of serum 25-OHD concentration accompanied by a decrease in serum 1,25-(OH)2D concentration. The results indicate that the circulating levels of 1,25-(OH)2D in patients with end-stage renal failure are to some extent regulated by the serum 25-OHD concentrations. Injection of parathyroid hormone (PTH) induced minor increases in serum concentrations of 1,25-(OH)2D in patients with end-stage renal failure and even in anephric patients, suggesting the existence of an extrarenal PTH-sensitive 1-alpha-hydroxylase. However, the enzyme was stimulated by supraphysiological concentrations of PTH, and therefore not necessarily of importance in the normal regulation of calcium metabolism.     

Efficacy of Amodiaquine in uncomplicated falciparum malaria in Nigeria in an area with high-level resistance to Chloroquine and Sulphadoxine/Pyrimethamine

Falciparum Malaria is hyperendemic in southern Nigeria and chloroquine resistance is an increasing problem. Therefore, the parasitological and haematological response to treatment with amodiaquine was studied in children under 5 years during a 14-day follow-up. Of 105 children who accomplished the study (out of 114 who were enrolled), 95.3% were parasite-negative on thick blood film on day 7, which decreased to 89.5% on day 14. The haemoglobin levels increased on average by 1.3% on day 14 (±1.9) and more pronounced in children with anaemia < 10 g/dl on enrolment. The number of patients with adverse events (mainly pruritus and nausea) was few. This study shows that amodiaquine is effective, safe and affordable in an area with high resistance to chloroquine.     

Radiation dose measurements with alanine/agarose gel and thin alanine films around a 192Ir brachytherapy source,using ESR spectroscopy

Alanine/agarose gel and alanine films in stacks have been used for measurements of absorbed dose around an HDR 192Ir source in a vaginal cylinder-applicator, with and without a 180 degrees tungsten shield. The gel and the films were analysed by means of ESR spectroscopy and calibrated against an ion chamber in a 4 MV photon beam to obtain absolute dose values. The gel serves as both dosimeter and phantom material, and the thin (130 microm) films are used to achieve an improved spatial resolution in the dose estimations. Experimental values were compared with Monte Carlo simulations using two different codes. Results from the measurements generally agree with the simulations to within 5%, for both the alanine/agarose gel and the alanine films.     

Influence of age and cell number of a tissue culture on its susceptibility to poliovirus

Summary By means of comparative virus titrations it is shown that significantly different titers may be found as a result of experimentally produced variations in the cultures used for titrations. The results were obtained by following the cytopathic changes daily in the microscope. The applied variations concerned the following factors: Age of the cultures used, time for last fluid change before virus inoculation and cell number of cultures of same age.Supported by a grant from the Swedish Association against Polio.