Evidence in support of the active ion transport by the ciliary body epithelium as the major mechanism of aqueous humor formation (AHF) has been accumulated. This paper reviews the recent progress in research and discussion of the following topics;
i) the structure of the ciliary body epithelium
ii) the composition of the aqueous humor
iii) the contribution of active ion transport to AHF
iv) the active transport of Na, Cl and HCO₃
v) the neural and humoral factors which affect AHF
vi) the possible role of pigmented cells on AHF

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The biomedical applications of synthetic polymer membranes are based upon following properties of polymers : (1) the biocompatibility represented as the blood compatibility and the tissue compatibility, (2) the processability represented as the spinning of hollow fiber and the micro-encapsulation, (3) the chemical functionality and its regulation by the polymer effect, (4) the mechanical properties and the biostability. The contributions of these characteristic properties to the following aspects of biomedical application are discussed : (1) The hemopurificatory membranes such as artificial kidney, plasma separator and artificial oxygenator, artificial skins, and contact lenses, (2) the diagnostic and therapeutic membranes such as drug-releasing membrane and immobilized-biopolymer membrane for clinical chemical assay, (3) the artificial cell membrane such as drug delivery system and hybridized cell membrane. The unsolved problems involved in the present stage of biomedical application are pointed out, and the subjects of future challenge are targeted.

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Recent developments of reverse osmosis membranes are reviewed from the point of synthetic composite membrane.
Newly developed synthetic composite membrane, designated, PEC-1000 makes it possible to perform high water recovery operation in single-stage seawater desalination due to it's high salt rejection and water flux, even under high temperature, high pressure and high feed salinity seawater as present in theMiddle East (which we designate the complete single-stage seawater desalination).
PEC-1000 membrane shows high solute rejection for valuable water-soluble organic materials of low molecular weight at the evaluation condition of high feed water concentration.
.PEC-1000 membrane also shows over 10 times higher solute rejection than that of the present commercialized membrane to various water-soluble inorganic compounds. For instance, it shows over 99.9% ion rejection for Cu²⁺, Co²⁺, Ni²⁺, or Fe (CN) ₆^4-ion at 56kg/cm², 25°C, 1% aqueous solutions.
Field Tests are being conducted on PEC-1000 membrane element for the concentration of aqueous ε-caprolactam, acetic acid and ethylene glycol solution. Tests results show both solute rejection and water flux are quite stable over 5000 hours.
These data indicate that PEC-1000 membrane exhibits it's capable applications to a variety of field where the application of conventional reverse osmosis membrane is regarded as impossible.

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Recently peritoneal dialysis is renewed by the popularity of continuous ambulatory peritoneal dialysis (CAPD). In CAPD peritoneal dialysis solution may be left in the peritoneal cavity for 4 to 12 hrs prior to drainage. There are many questions about the ultrafiltration and the transport processes of solutes in the long dwelling. So a mathematical model of the peritoneal dialysis system is essential to the analysis of the kinetics of solutes and fluids. Peritoneal membrane is heteroporous and mosaic but our approach considers such structural detail explicitly idealized homoporous membrane.
In 5 patients undergoing peritoneal dialysis, 1.5% and 4.25% dextrose dialysis solutions containing RISA were instilled and dwelled for 6 hrs respectively. In the dwelling period 10 ml of dialysis solutions were sampled serially. The samples of dialysis solutions and serum were analysed the concentrations of solutes and ¹³¹I. We could calculate the mass transfer area coefficient, the reflection coefficient and so on, solving the equations for volume flux and solute flow of nonequiliblium thermodynamics. Peritoneal ultrafiltration to dialysis solution stops and reabsorption starts while the osmotic pressure of dialysis solution is higher than that of serum. In each case the reflection coefficient of sodium is more than those of glucose and urea.
We conclude that the dialysis solution might be reabsorbed by the sodium gradient between dialysis solution and serum despite the opposite higher gradient of glucose.

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Cholera is a disease caused by cholera enterotoxin produced by Vibrio cholerae. Main symptom of cholera is watery diarrhea and it is caused by cholera enterotoxin. Cholera enterotoxin is a protein toxin and its molecular weight is about 84, 000. It consists of two subunits, A and B. B subunit is a binding subunit and it binds to GM1 ganglioside of epithelial cell membrane of intestinal brush border. After the toxin binds to G_M1 ganglioside through B subunit, A subunit is incorporated into the cell and it stimulates membrane bound adenylate cyclase. The mechanism of the stimulation of adenylate cyclase by cholera enterotoxin is well established. However, the mechanism how the increase of cyclic AMP concentration in intestinal cell results in an excess secretion of water into intestinal lumen is still not understood.

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