Molecular mechanism of proton pumping of bacteriorhodopsin in purple membranes is reviewed on the bases of the recent results of 3.7Å resolution of bacteriorhodopsin structure and of photochemical studies. The content is as follows: 1) Function of purple membrane in halobacteria, 2) Structure of purple membranes, 3) Photochemistry of bacteriorhodopsin, 4) Molecular mechanism of proton pumping.

抄録全体を表示

Photoacoustic spectroscopy (PAS) has already found many important applications in the research and characterization of materials covering full range of matter: solid, liquid, and gas; inorganic, and biological. Light that is transmittered, reflected, or elastically scattered by the sample is not determined, and hence does not interfere with the inherently absorptive PAS measurement. This is very important in the measurement and analysis of highly transparent or highly light scattering materials such as the thin film and the membrane.
The present review is mainly concerned with applications of PAS to the thin film and the membrane of some kinds of materials including biological samples. The principle of PAS relating to the film thickness measurement and the depth profile spectroscopic analysis is also briefly discussed.

抄録全体を表示

Physiological studies on diuretics have revealed that the main action site of diuretics is the tubular membrane. However, more detailed mechanism on molecular basis still remains obscure. We have first tried to obtain the electronic state of loop diuretics (ethacrynic acid and furosemide) and thiazide diuretics. The result was further examined from the aspect of the tubular membrane and mitochondrial membrane of the kidney. The electronic state of these diuretics was calculated by simple Mickel Molecular Orbital Method. The result showed that these diuretics have an electron accepting nature. This specific nature of ethacrynic acid and furosernide could be related to our biochemical experimental result which these diuretics inhibited the electron transport system in mitochondria of rat kidney. This reduction of energy production might explain the inhibition of tubular sodium reabsorption by loop diuretics. Other possibility might be some electrostatic or charge transfer interaction between these diuretics and the action site of the tubular membrane.
On the other hand, thiazide diuretics has not any effect on mitochondrial respiration. A more advanced molecular orbital calculation (CNDO/2) and structure activity relation analysis by Hansch and Fujita on thiazide diuretics and their analogues showed that formal charges of the 3rd, 4th, 5th and 6th carbons of thiazide ring and hydrophobic index of the atom or group introduced to the 4th carbon atom were mainly related to diuretic activity. We assumed a receptor model for thiazide diuretics probably located in the urinary surface of tubular membrane consisted of a hydrophobic center and the four electrostatically reactive carbon atoms.

抄録全体を表示

Membranes which can convert chemical potential difference into electicity are reviewed. Theoretical treatment of the process based on irreversible thermodynamics by Kedem & Caplan is briefed first. Conversion of temperature difference into electricity, using thermocouples is shown as a familiar example. Possibility of reverse electrodialysis battery using pairs of ion exchange membranes has been reviewed. And also pressure retarded osmosis studied by Loeb has been reviewed.

抄録全体を表示

Although high Na hemodialysis has several advantages over low Na or usual HD, the optimal Na concentration of dialysate must be different for each patient. We developed a biological model to estimate intracellular and extracellular fluid volume during HD using ICF and ECF before HD and dialysate Na concentration. Furthermore, we made another model to estimate ICF and ECF before HD using the sex of the patient, body build, dry weight, body weight and serum [Na] before HD. Combining these models, we can simulate ICF, ECF, and serum [Na] at any time during the treatment by HD. Therefore, the optimal dialysate Na concentration can be determined in individual patients, if serum [Na] at the end of HD is settled. Since serum [Na] is generally low and ICF is increased before HD, serum [Na] should be corrected around 145 mEq/l to normalize ICF by HD.
The optimal dialysate Na concentration based on our models is approximately 150 mEq/l for Japanese men, however, should be variable by body fluid volume of the patient (body weight, sex, build), ultrafiltration rate, dialyser's clearance, serum [Na] before HD and the duration of HD. Now that Na infusers adjusting dialysate Na concentration to the optimal level have been available, prescription of high Na hemodialysis for individual patients becomes practically possible.

抄録全体を表示

Two types of devices for sustained release of methotrexate in the uterus were prepared for the purpose of prevention of choriocarcinoma. One is a hydrogel piece of cross-linked copolymer of N-vinylpyrrolidone in which methotrexate is precipitated. The other is a hydrogel capsule made of the cross-linked blend of polyurethane and poly (N-vinylpyrrolidone) that is packed with methotrexate. In the experiment in vitro, the rate of the drug elution from the former device decreased as the elution proceeded. On the other hand, the elution rate was constant in the latter case in which the drug was released through the hydrogel membrane. In the animal experiments, the devices were inseredt into the uteri of rabbits. The elution rate in vivo was shown to be close to that in vitro in either case of the two types of devices. The numbers of white blood cells were found to be within a normal range in all the rabbits that had been dosed with 17-20mg of methotrexate in the uterus for 14 days. No abnormal symptom was recognized in macroscopic and histopathological examinations on the endometria of these rabbits.

抄録全体を表示