Novel activity of melatonin. Its chemotactic effect on retinal pigment epithelial cells

Melatonin (100 nM-100 microM) showed a chemotactic action on cultured chick retinal pigment epithelial cells. This effect was equivalent to that of N-formyl methionyl-leucyl-phenylalanine. Other methoxyindole derivatives had no or less chemotactic effects than melatonin.

Retinal pigment epithelial cells produce fibronectin

Antichick fibronectin antiserum, noncross-reactive to bovine fibronectin, was prepared to determine the production of fibronectin by cultured chick retinal pigment epithelial cells which were grown in the presence of fetal bovine serum. The typical fibrillary net pattern of fibronectin was observed by an indirect immunofluorescent technique when this specific antiserum reacted with cultured chick retinal pigment epithelial cells. Cultured chick retinal pigment epithelial cells were shown to produce fibronectin.

Juvenile retinal detachment

The features and prognoses of 802 cases (908 eyes) of retinal detachment from 8 months to 19 years of age were studied with the patients divided into three age groups: 65 eyes in group I (0-9), 259 eyes in group II (10-14), and 584 eyes in group III (15-19). Eyes in group I were different from the others in many respects. In group I, traumatic detachments, preoperative complications, four-quadrant detachments, and eyes with undetected breaks were more frequent, and the prognosis was worse than in the other groups. Holes with lattice degenerations were most frequent in group III eyes having no history of trauma. Group III resembled adult retinal detachment and group II was thought to be the transitional type.

Idiopathic epiretinal membranes with spontaneous posterior vitreous separation

A posterior fundus examination around the macula was performed for the patients diagnosed spontaneous posterior vitreous separation. Of 898 eyes, 358 eyes had epiretinal membranes. The presence of membranes did not correlate to sex. The 2-fold greater incidence was observed in the aged group and emmetropic patients. For the progression, age, sex or refractive error alone was not significant, while aged, emmetropic patients showed greater incidence. The longer duration of the membrane existence also indicated the greater progression.

Cell components in proliferative vitreoretinopathy: immunofluorescent double staining of cultured cells from proliferative tissues

Intermediate filament proteins in cultured cells from epiretinal membranes of 5 cases of proliferative vitreoretinopathy and subretinal strands of 2 cases were immunohistologically characterized. Double staining technique after colcemid treatment revealed that either keratin-positive or vimentin-positive cells were found with different ratios depending on the cases. Both positive and both negative cells were also observed. Desmin and glial fibrillary acidic protein were totally negative.

Chick retinal pigment epithelium exhibits glutathione requiring prostaglandin D2 synthetase activity

Prostaglandin synthetic activity of neural retina and retinal pigment epithelium in chick retina was studied using arachidonic acid and prostaglandin H2 (intermediate prostaglandin endoperoxide) as substrates. To obtain sufficient enzyme activity in retinal pigment epithelium, cultured chick retinal pigment epithelial cells were used. Little arachidonic acid was converted into prostaglandins, and details of prostaglandin synthetic activity were not clear. The assay from prostaglandin H2 showed that: 1) preparations consisting of both neural retina and retinal pigment epithelium dissected from 7-day-old chicks have activity of glutathione-requiring prostaglandin D2 synthetase; 2) preparations consisting of only neural retina dissected from 7-day-old chicks have no activity of prostaglandin synthetase; and 3) cultured chick retinal pigment epithelial cells have high activity of glutathione-requiring prostaglandin D2 synthetase.

Omental transposition and skin graft in patients for advanced or recurrent breast cancer

Nine patients, including 4 with primary advanced breast cancer (stage IV) and 5 with local recurrent cancer, underwent chest wall reconstruction using an omental flap and mesh skin grafting. In 2 of these patients the defect of bony chest wall was reconstructed with an acryl-resin plate and omental flap. The postoperative course in all patients was uneventful, except for a slight necrosis on the transposed mesh skin. Flail chest or dyspnea did not occur in those with a bony chest wall reconstruction. The immediate postoperative performance status in 6 of 9 patients and also quality of life improved.

Effects of phenothiazines on cultured retinal pigment epithelial cells

Phenothiazines (chlorpromazine, trifluoperazine, prochlorperazine, and fluphenazine) showed dose-dependent inhibition of phagocytosis of latex particles by cultured chick retinal pigment epithelial cells at concentrations of 10(-5)-10(-14) mol/l. Calmodulin antagonists (W-5, W-7, W-12, and W-13) showed similar effects as phenothiazines at concentrations of 10(-5)-10(-14) mol/l. These reactions were partially reversible at a concentration of 10(-9) mol/l. Cells cultured for 3 days in the presence of 10(-5) mol/l chlorpromazine or 10(-5) mol/l W-7 demonstrated morphologic alterations in their microvilli which were similar to those seen after cytochalasin B treatment, i.e., thinning and elongation of the microvilli with honeycomb-like changes.

Growth factors induce actin disruption in cultured human retinal pigment epithelial cells

Exposure of cultured human retinal pigment epithelial cells to platelet-derived growth factor, nerve growth factor or epidermal growth factor resulted in a time- and dose-dependent alteration in the distribution of actin stained by rhodamine-phalloidin. These growth factors (platelet-derived growth factor of 80 ng/ml, nerve growth factor of 10 ng/ml or epidermal growth factor of 10 ng/ml) caused disappearance of actin filaments from the peripheral region of a cell in 1 or 2 h and change of cell configuration to spindle shape in 3 or 4 h. Other growth factors, fibroblast growth factor of 10 ng/ml and insulin of 25 mumol/ml had no effect on actin distribution. The alteration of actin and the change of cellular shape might be associated with stimulation of cell growth and migration of retinal pigment epithelial cells.

Exocytosis by retinal pigment epithelial cells

We observed cultured retinal pigment epithelial cells as they responded to the introduction of latex particles. The cells showed phagocytosis of particles 1 h after administration of latex and were filled with particles after 24 h. After 7 days, exocytosis of latex from basal plasma membrane was documented. Observation was repeated using a two-layer culture. 7 days after putting the retinal pigment epithelial layer containing latex particles on another layer without particles, we observed the appearance of latex particles in the lower layer that originally contained no particles. This demonstrated that cultured retinal pigment epithelial cells exocytose latex particles from basal cell membrane.

Phagocytic activity of cultured retinal pigment epithelial cells from chick embryo: inhibition by melatonin and cyclic AMP, and its reversal by taurine and cyclic GMP

Cultured chick retinal pigment epithelial cells phagocytosed polystyrene latex particles. The phagocytosis was inhibited very specifically by melatonin, which attained 50% inhibition at about 10(-16) M. Other indole compounds such as 5-methoxytryptophol, 5-hydroxytryptophol, 6-hydroxymelatonin, N-acetylserotonin, 5-methoxytryptamine and serotonin were also inhibitory although their effects were less than 1/10,000 that of melatonin. Possible retinal neurotransmitters, acetylcholine, gamma-aminobutyric acid, glycine, dopamine, aspartic acid and glutamic acid, had no or only a minimum inhibitory effect, and was also the case for prostaglandin D2, E2, F2 alpha, and I2. Taurine was not inhibitory at all. Among nucleotides, cyclic AMP specifically inhibited phagocytosis, giving 50% inhibition at about 10(-11) M. Melatonin inhibition was increased by copresence of isobutylmethylxanthine. Inhibition by either melatonin or cyclic AMP was reversed by dibutyryl cyclic GMP. The reversal was observed also with compounds which were expected to increase intracellular cyclic GMP. Prostaglandin D2 reversed inhibition in both cases, but its effect was incomplete and per se it had an inhibitory effect. Melatonin derivatives reversed inhibition by melatonin alone but not inhibition by cyclic AMP. Taurine efficiently reversed both kinds of inhibition. Other possible neurotransmitters were ineffective. Taurine was thus the most effective of these compounds. We suggest the following hypothetic control mechanism of phagocytic activity of the pigment epithelial cells: melatonin and cyclic AMP are intercellular and intracellular signals, respectively, of stopping phagocytosis, while taurine and cyclic GMP are intercellular and intracellular signals, respectively of cancelling this stop signal. Phagocytic activity of chick retinal pigment epithelial cells might be regulated by the concentration ratio of melatonin to taurine in the interphotoreceptor space.

Effects of thermal load on ion release of the rabbit vitreous body

Ion-release of the rabbit vitreous body through a dialysis membrane against water was studied. To evaluate one of thermal changes in the vitreous properties, the vitreous was heated or cooled before dialysis. The average wet weight of the normal vitreous was 1.61 +/- 0.20 g and dry to wet weight ratio was 1.33 +/- 0.04%. The dry weight, sodium, potassium, and chloride concentrations of the vitreous were decreased as an exponential function curve by dialysis. A decreasing ratio was prominent in the heated vitreous, the frozen vitreous and the non-thermo-treated (control) vitreous in turn. Calcium and magnesium release from the rabbit vitreous body was slow and differences among the heated, frozen and non-thermo-treated vitreous bodies were not significant, suggesting some different capture-mechanisms between the monovalent and bivalent ions.