Yozo Ogura

Sensitive colorimetric assay of serum diamine oxidase

A simple and sensitive colorimetric assay for serum diamine oxidase (DAO) activity was based on a coupled reaction with peroxidase and a new chromogen, 10-(carboxymethyl-aminocarbonyl)-3,7-bis(dimethylamino) phenothiazine sodium salt (DA-67). In the presence of peroxidase and DA-67, peroxidase catalyzes the formation of methylene blue having an absorption maximum at 668 nm. The proposed method eliminates the interferences occurring in serum with use of ascorbate oxidase and stops the reaction with sodium diethyldithiocarbamate, leaving the methylene blue in the reaction mixture stable for about 2 h. Low normal basal values of serum DAO can be determined in the range 2.8-9.0 units/l. Since all reagents are commercially available the method is suitable for the clinical laboratory.

Usefulness of soluble dietary fiber for the treatment of diarrhea during enteral nutrition in elderly patients.

OBJECTIVES We investigated the clinical usefulness of soluble dietary fiber (SDF) for the treatment of diarrhea during enteral nutrition in elderly patients. METHODS This study included 10 men and 10 women (mean age +/- standard deviation: 79.3 +/- 5.1 y) who had diarrhea during long-term nutrition management. When administering SDF, the initial dose was 7 g and thereafter gradually increased at 1-wk intervals. After 4 wk, the administration was discontinued for 2 wk to confirm the effects of SDF. RESULTS After the administration of SDF, serum diamine oxidase activity significantly increased (P < 0.001): The water content of the feces decreased significantly after the administration of fiber (P < 0.01). The frequency of daily bowel movements also decreased significantly (P < 0.05). Simultaneously, the fecal features improved. Concerning intestinal flora, there were no significant changes in the total number of bacteria or the number of anaerobic bacteria. The fecal pH decreased significantly 4 wk after the administration of fiber (P < 0.05). The total level of short-chain fatty acids increased significantly 4 wk after the administration of fiber (P < 0.05). There were no significant changes in the various nutritional indices. CONCLUSIONS The administration of SDF is useful for controlling spontaneous, favorable bowel movement by improving symptoms of small intestinal mucosal atrophy and normalizing the intestinal flora.

Interference of hematocrit in the tacrolimus II microparticle enzyme immunoassay.

The authors studied the effect of hematocrit, bilirubin, and alkaline phosphatase on microparticle enzyme immunoassay for tacrolimus II (MEIA II) using specimens of whole blood obtained from 33 patients undergoing cyclosporine treatment. Tacrolimus was added to these samples at a final concentration of 7.5 &mgr;g/L and 15 &mgr;g/L. Both coefficients of variation were over 20% (21% at 7.5 &mgr;g/L of tacrolimus and 22% at 15 &mgr;g/L of tacrolimus). No correlation was found between bilirubin and tacrolimus concentrations or between alkaline phosphatase and tacrolimus concentrations. On the other hand, negative correlations were found between hematocrit values and tacrolimus concentrations (r2 = 0.47;P < 0.0001 at 7.5 &mgr;g/L tacrolimus, r2 = 0.54;P < 0.0001 at 15 &mgr;g/L tacrolimus). Negative correlations were also found between hematocrit and the tacrolimus concentration using normal human red blood cells diluted with physiological saline solution (r2 = 0.93;P < 0.0001 at 7.5 &mgr;g/L tacrolimus, r2 = 0.91;P < 0.0001 at 15 &mgr;g/L tacrolimus). The results showed that the hematocrit interferes with the MEIA II for tacrolimus, and the magnitude of the interference is clinically significant. Beyond the normal range of hematocrit values, caution should be exercised in interpreting results as one may need to compensate for the levels of tacrolimus.

Comparative Studies on Interaction Between Theophylline and Quinolones

A comparative study of the pharmacokinetic and metabolic interactions between theophylline and a newly developed quinolone, T-3262, was carried out under steady-state conditions in seven healthy male volunteers, using enoxacin as the reference drug. A sustained-release theophylline formulation (200 mg twice daily) was given as monotherapy and coadministered with T-3262 (150 mg three times a day) or enoxacin (200 mg three times a day). The total and free concentrations of theophylline in the plasma and the excreted concentration of theophylline and its metabolites in the urine were measured by a high-performance liquid chromatography method. The mean steady-state plasma theophylline concentration significantly increased by approximately 1.5-fold and threefold after coadministration of T-3262 and enoxacin, respectively. In both cases, a significant decrease in the total body clearance was found for T-3262 (34%) and enoxacin (63%), but the plasma protein binding of theophylline remained unchanged. There was a significant increase in urinary theophylline and a decrease in urinary 3-methylxanthine after coadministration of T-3262 or enoxacin. The degree of change in the steady-state plasma theophylline concentration as a result of coadministration of T-3262 was small compared to that of enoxacin. A decrease in the total body clearance in the case of coadministration of a quinolone probably resulted from inhibition of the 1-demethylation metabolic pathway.

EFFECT OF TRANSMUCOSAL FLUID MOVEMENT ON ZINC AND COPPER ABSORPTION FROM THE RAT SMALL INTESTINE

1. The effects of transmucosal fluid movement on zinc and copper absorption from rat small intestine were investigated using an in situ recirculating perfusion method.

Kinetic interaction between theophylline and a newly developed anti-allergic drug, pemirolast potassium

The effect of a newly developed anti-allergic drug, pemirolast potassium (TBX), on the pharmacokinetics and metabolism of theophylline was investigated under steady-state conditions in seven healthy male volunteers. A sustained-release theophylline formulation (100 mg twice daily at 12 h intervals) was given as monotherapy and coadministered with TBX (10 mg twice daily at 12 h). Plasma concentration-time curves and the urinary excretion of theophylline and its major metabolites after administration of theophylline alone and after coadministration with TBX were compared.No significant adverse effects from this study were observed. There were no significant differences in the total body clearance, renal clearance and maximum concentration of theophylline between the two treatments, although coadministration of TBX significantly delayed the time to reach maximum concentration of theophylline. In the case of urinary excretion, no significant changes in the fraction of urinary excretion of theophylline and its metabolites were observed. These results indicate that TBX has little or no effect on the pharmacokinetics and metabolism of theophylline and suggest that TBX is safe for asthma patients receiving theophylline therapy for treatment of chronic obstructive airway diseases.

Lack of effect of repirinast on the pharmacokinetics of theophylline in asthmatic patients

SummaryA possible pharmacokinetic interaction between theophylline and repirinast has been investigated in asthmatic patients. The kinetics of theophylline was studied in seven adult in-patients given theophylline 400–800 mg b.d. alone and after three weeks of co-administration of repirinast.There was no effect on the kinetics of the combined treatment.

Congestion of Superior Mesenteric Veins and Small Bowel Mucosal Injury After Endoscopic Treatment of Esophageal Varices in Patients with Portal Hypertension

We investigated treatment-induced changes in venous return from the small bowel and small bowel intestinal mucosal injury induced by the treatment of esophageal varices in patients with portal hypertension. A total of 14 patients (age 59.8 ± 9.5 years, five women and 9 men) who received prophylactic treatment of esophageal varices between December 1998 and March 1999 were investigated. Diamine oxidase (DAO) activity was measured before and after treatment. Changes in blood flow of the portal and superior mesenteric veins were investigated by Doppler ultrasonography in six patients. A significant decrease in DAO activity was observed three days after treatment (11.5 ± 1.6 units/liter prior to treatment versus 8.6 ± 1.6 units/liter three days after treatment; P < 0.001). Decreases in superior mesenteric and portal venous flow velocity were observed in four and three patients, respectively. In two patients with an increase in the cross-sectional area of the superior mesenteric vein with delayed venous return, a marked decrease in DAO activity was observed three days after treatment. In patients with portal hypertension, rapid reduction of pooling of portal flow caused by the treatment of esophageal varices can induce transient congestion of the mesenteric venous system which can produce some small bowel mucosal injury.

Clinical evaluation of theophylline binding to plasma protein in bronchial asthmatic patients.

Theophylline binding to plasma protein was studied with seven bronchial asthmatic inpatients. The extent of protein binding was monitored using an ultrafiltration device, EMIT® FreeLevelTM System 1, whose performance is pH independent between 7·5 and 8·5 and concentration independent between 2 and 10 mcg/ml. When protein‐free theophylline solutions are used a linear pH dependency was observed between 7·0 and 8.3. With theophylline‐spiked human plasma using the same samples, the binding was found to be concentration‐independent in the range 5 to 40 mcg/ml. The intra‐ and inter‐individual variations in theophylline binding to plasma proteins were relatively large. A calculation procedure for predicting free fractions at normal physiological plasma pH, 7.4, using the observed free fraction at a given plasma pH is proposed. A good correlation was obtained between plasma and salivary theophylline concentrations. Salivary levels alone, however, are unreliable for monitoring theophylline therapy.

Rectal Absorption of Aminophylline Suppository

Mode of rectal absorption of aminophylline was examined with 3 kinds of suppository bases, macrogol, Vosco H-15, and Vosco S-55. Plasma concentration of theophylline after rectal and oral administration was also measured on the subjects of 5 healthy adults. Measurement was made by the high-pressure liquid chromatography.Drug releasing test was made by the method of Kakemi et al. Physical property, melting point, dissolution time, and other properties of the suppository were measured. The drug releasing test demonstrated that the release of aminophylline from macrogol base was faster than that from Vosco bases (in vitro test). Plasma concentration of theophylline was found higher in the oleaginous base (Vosco) than in the water-soluble base (macrogol). This is contradictory to the finding in vitro test.In the human experiment, the highest mean plasma concentration of theophylline, 1.29 μg/ml., was observed 1 hour after rectal administration. The highest plasma concentration by rectal administration was slightly lower than that by oral administration.