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Biomedical subjects

K Iwamoto

Publications and source records attributed to K Iwamoto.

At least 145 records · Page 8Linked to original sources
PubMed1990

High-performance liquid chromatographic determination of ciprofloxacin in rat brain and cerebrospinal fluid.

A novel high-performance liquid chromatographic method for the fluorometric determination of a newer quinolone, ciprofloxacin (CPFX), in rat brain and cerebrospinal fluid (CSF) was developed. CPFX in brain homogenate was extracted and injected onto a reversed-phase column without fluorescence derivatization. CSF was directly analyzed without the extraction procedure. Calibration curves were linear over the concentration ranges of 10 to 500 ng/g for brain and 5 to 500 ng/ml for CSF. The recoveries of CPFX added to brain were more than 97% with a coefficient of variation of less than 4%. The present method was sensitive and reliable enough to be utilized for detailed pharmacokinetic studies of CPFX in rat brain and CSF.

Animals↗
PubMed1990

[Comparison by 31P magnetic resonance spectroscopy of effect of simple immersion and continuous perfusion methods on organ viability of preserved rat hearts].

31P magnetic resonance spectroscopy was used to measure high energy phosphates of the heart continuously as an index of the viability of the preserved organ together with the cardiac function after preservation. Results with the simple immersion (SI) and the continuous perfusion (CP) methods were compared. With SI, ATP decreased to 14.8 +/- 4.1% of the base line after 12 hr of preservation, and phosphocreatine decreased to 27.8 +/- 6.2% after 3 hr, remaining at about 30% of the base line thereafter. With CP, ATP and phosphocreatine were unchanged even after 24 hr of preservation; they were 99.1 +/- 2.6% and 119.6 +/- 6.7%, respectively. The ATP/Pi ratio was 5.4 +/- 0.7% after 12 hr with SI and 62.2 +/- 5.8% after 24 hr with CP. LV dP/dt was 96.6 +/- 11.5% after 3 hr of SI (3-SI), which was not significantly different from the control. After 6 hr of SI (6-SI), the value was 122.7 +/- 0.2%, significantly higher (p less than 0.01) than the control. After 9 hr of SI (9-SI) or after 24 hr of CP (24-CP), it was 80.8 +/- 4.6% and 67.8 +/- 8.2%, respectively, both were significantly lower (p less than 0.01) than the control. The rate-pressure product returned to the control level after 3-SI and 6-SI, but after 9-SI or 24-CP, it was 74.2 +/- 3.7% and 53.0 +/- 11.0%, and they were significantly (p less than 0.01) lower than the control.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1990

[Effect of adenosine on recovery of lowered viability of preserved rat hearts measured by 31P magnetic resonance spectroscopy].

The restoration of the viability of rat hearts preserved for 5 hr by 50 microM adenosine (ADN) was evaluated in terms of the cardiac function after preservation and the recovery of myocardial high energy phosphates measured by 31P magnetic resonance spectroscopy. The hearts were perfused with modified Krebs-Ringer's solution (mKRS) with ADN (ADN group) or without AND (non-ADN group) for 1 hour after 5 hr of preservation by the simple immersion method. Control hearts were perfused but not preserved. ATP and phosphocreatine had decreased to 47.2 +/- 6.6% and 28.0 +/- 8.6% of the base line by 5 hr of preservation, but the levels returned to 147.2 +/- 2.3% and 127.4 +/- 5.6% after 1 hr of perfusion with ADN; at the same time, in the non-ADN group, they were 103.8 +/- 2.3% and 115.8 +/- 8.3% respectively. The same hearts were next perfused for 3 hr with standard Krebs-Ringer's solution so as to beat after the perfusion with mKRS. After 3 hr of beating, LV dP/dt was 3330 +/- 116 mmHg/s in the ADN group, which was not significantly different from the control (3034 +/- 60 mmHg/s). However, in the non-ADN group, the value was 2516 +/- 201 mmHg/s and significantly lower (p less than 0.05) than the control. The rate-pressure product was 19350 +/- 1154 in the ADN group, not significantly different from the control (20899 +/- 709), but it was 14559 +/- 1339 in the non-ADN group, which was significantly lower (p less than 0.01) than the control.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMed1990

[The frequency of patients with positive HIV-antibody in the various groups and the prognosis of these patients treated with SNMC].

Among 300 patients receiving blood and/or blood products because of blood disorders, 3 (1%) were positive for HIV by ELISA. However, 3 patients were thought to be false positive because they had received bolus injection of gamma-globulin and their serum became negative after 6 months. Moreover, no viral inclusion or HIV-antigen was detected. In 30 patients with hemophilia and related disorders, 21 (70%) were positive by ELISA, Immunofluorescence, Passive-agglutination and Western Blot method. Immunodeficiency, as reflected by decreases of CD 4/8 ratio and NK activity, was successfully treated with high-dose of Stronger Neo-Minophagen C.

Adolescent↗
PubMed1989

Adriamycin-lipiodol suspension for i.a. chemotherapy of hepatocellular carcinoma.

Physicochemical properties of two types of adriamycin preparation, suspensions and emulsions prepared for i.a. chemotherapy of hepatocellular carcinoma, were investigated. A suspension was prepared by dispersing adriamycin directly into the lipid contrast medium, Lipiodol, whereas an emulsion was obtained by emulsifying an aqueous solution of adriamycin into Lipiodol. The dispersibility of the drug in each preparation was examined microscopically. The chemical stability of and drug release from the preparation were determined by high-performance liquid chromatography and spectrophotometry, respectively. The suspension was then given to ten patients with primary hepatocellular carcinoma. The suspension maintained good dispersibility without coagulation of drug particles, whereas coalescence of aqueous droplets and the resultant phase separation occurred 4 h after preparation of the emulsion. Both preparations maintained the initial drug content for at least 1 week at room temperature. The release of adriamycin was more prolonged in the suspension than in the emulsion. After i.a. administration of the suspension, a selective accumulation of Lipiodol in the tumor and decrease in serum alpha-fetoprotein (AFP) levels were found in most patients. A significant amount of adriamycin was still detected in hepatic specimens resected from two patients 1 and 2 months after treatment. These findings suggest that the adriamycin-Lipiodol suspension may be a useful preparation for targeting chemotherapy to hepatocellular carcinoma.

Adult↗
PubMed1989

Absence of pharmacokinetic interaction between ofloxacin and fenbufen in rats.

The possible pharmacokinetic interaction between a new quinolone and fenbufen was investigated by comparing the plasma concentration-time profiles and serum protein binding of ofloxacin, fenbufen and its active metabolite, felbinac, in rats. The rats were administered intravenous doses of ofloxacin (5 mg kg-1), fenbufen (10 mg kg-1) alone or concomitantly. The plasma elimination half-lives were about 55 min in both groups. A slight elevation of plasma concentration of ofloxacin and a small decrease of its total body clearance were observed after its coadministration with fenbufen. The extent of ofloxacin binding to rat serum tended to be slightly reduced by fenbufen which coexisted at relatively high concentrations. Plasma concentration-time curves, pharmacokinetic parameters and serum protein binding of fenbufen and felbinac were not affected by the coadministration with ofloxacin. These results suggest that any substantive pharmacokinetic interaction may be unlikely after the concomitant administration of ofloxacin and fenbufen.

Animals↗
PubMed1989

Effects of bovine serum albumin and recirculation rate on the uptake of propranolol by rat perfused lung.

Lungs isolated from 7-week-old rats were perfused with pH 7.4, oxygenated Krebs-Ringer bicarbonate buffer solution containing 2.5 micrograms mL-1 of propranolol and 3 to 5% BSA at the recirculation rate of 4 to 16 mL min-1, at 37 degrees C for 60 min. The extent of propranolol metabolism after 60 min was less than 2.3% of the initial load under any in-vitro perfusion condition. Therefore, the amount disappearing from the perfusion medium was considered as being predominantly that taken up by tissue. Under all experimental conditions, perfusate drug level declined bi-exponentially with time. Apparent in-vitro pulmonary clearance of propranolol was not affected by the increase of BSA level from 3 to 5%. When the perfusate BSA level was fixed at 3%, the lowest recirculation rate (4 mL min-1) yielded the smallest clearance (about 0.15 mL min-1 g-1) but almost constant clearance value (about 0.40 mL min-1 g-1) was obtained at the rate ranging from 8 to 16 mL min-1. The tissue to medium concentration ratio of propranolol, after the perfusion with 3 to 5% BSA at the rate of 8 to 16 mL min-1, was approximately 35, whereas that with 3% BSA at 4 mL min-1 was reduced to about 20. The findings suggest evidence for flow-dependent in-vitro pulmonary clearance of propranolol.

Animals↗
PubMed1989

Specific age-dependence in capacity-limited uptake of propranolol by isolated rat lung.

To investigate the effect of age on the pulmonary uptake of propranolol, minced tissue (0.4 g) of lungs isolated from 3- to 104-week-old rats was incubated with the drug (1 to 500 micrograms mL-1) prepared in oxygenated, pH 7.4 Krebs-Ringer bicarbonate buffer solution (20 mL) containing 3% BSA for 60 min at 37 degrees C. In any age-group the metabolism of propranolol was not significant (i.e. less than 0.6% of any initial load) under the present in-vitro conditions. The extent of uptake after the incubation with 2.5 micrograms mL-1 of the drug was largest in the 7 weeks (i.e. 82% of the initial load) and relatively small in the 3(64%), 24(61%), 52(51%) and 104(48%) week old rats. Similar, specific age-dependence was observed in the tissue-to-medium concentration ratio of the drug. In any age-group, the initial uptake rate obtained in the first 5 min of the incubation was found to be a combination of apparently linear transport and saturable (capacity-limited) processes. There was a marked, specific age-dependence in the capacity-limited uptake rate. Although Km' value was almost equivalent in any age-group (i.e. 24.4 to 25.4 micrograms mL-1), Vmax exhibited a specific age-dependence by yielding the highest value in 7 weeks (0.726 +/- 0.101 mg g-1 min-1) and relatively low values in 3 (0.501 +/- 0.082 mg g-1 min-1), 52 (0.410 +/- 0.088 mg-1 g-1 min-1) and 104 (0.397 +/- 0.074 mg g-1 min-1) weeks.

Aging↗
PubMed1989

Effects of metabolic inhibitors and incubation temperature on the saturable uptake of propranolol by isolated rat lung tissue.

The effects of several metabolic inhibitors (50 microM) on the initial uptake rate of propranolol (0.5 to 500 micrograms mL-1) by the minced lungs (0.4 g) isolated from 7-week-old rats has been investigated in oxygenated, pH 7.4 Krebs-Ringer bicarbonate buffer solution (20 mL) containing 3% BSA at 37 degrees C for 5 min. The effect of the incubation temperature was also examined. Metabolism of propranolol was almost insignificant (i.e. less than 1.3% of the initial load). The overall initial uptake rate was considered to be a combination of apparent linear transport and saturable processes. For the control uptake rate, the linear transport rate constant was 1.26 +/- 0.16 g-1 mL-1 min-1, while Vmax and Km' of the capacity limited uptake process were estimated as 0.727 +/- 0.074 mg g-1 min-1 and 24.8 +/- 2.71 micrograms mL-1, respectively. No metabolic inhibitor tested had an effect on the linear transport rate of propranolol but 2,4-dinitrophenol and potassium cyanide inhibited saturable uptake rate (i.e. Vmax) of propranolol significantly (P less than 0.01) while ouabain, phloridine and iodoacetic acid did not do so significantly. Reduction of the incubation temperature to 15 degrees C decreased and at 25 degrees C tended to decrease, both linear transport and saturable uptake rates.

Animals↗
PubMed1989

Radioactive metal complexes with affinity for tumors. II. Biodistribution of radioactivity in cellular and subcellular fractions of tumor tissues.

The 99mTc and 57Co complexes of ethylenediamine-N,N-diacetic acid (EDDA) are accumulated in tumor tissue. The complexes and related radioactive compounds were administered to experimental animals bearing Ehrlich tumor, and the blood, tumor, abscess, and other tissues were separated, fractionated and analyzed. In blood, the EDDA complexes of 99mTc and 57Co were in dialyzable forms, whereas other tumor-nonlocalizing compounds were in undialyzable or protein-bound forms. The tumor/blood and tumor/muscle ratios of the radioactivity showed that the complexes had the high affinity for tumor tissues. Density gradient centrifugation analysis of the ascites tumor tissues showed that a significant amount of the radioactivity of the complexes was present in tumor cells. Subcellular fractionation of solid tumor tissue showed that the radioactivity was present in nuclear fraction.

Animals↗
PubMed1989

High-performance liquid chromatographic procedure for the simultaneous determination of norfloxacin, fenbufen and felbinac in rat plasma.

A high-performance liquid chromatographic method for the simultaneous determination of norfloxacin, fenbufen and felbinac extracted from 50 microliters of rat plasma is described. Chromatography was performed on a reversed-phase column with ultraviolet detection. By the present method, quantitative and reproducible determinations were possible for norfloxacin, fenbufen and felbinac over the concentration ranges of 0.2-20, 0.2-120 and 0.4-40 micrograms/ml, respectively. The recoveries of norfloxacin, fenbufen and felbinac added to plasma were nearly 100% with a coefficient of variation of less than 8.0%. This method was found to be applicable to pharmacokinetic studies of each drug after the concomitant administration of norfloxacin and fenbufen.

Animals↗
PubMed1989

[Behavior of chlorpheniramine in vivo after administration of d- and l-chlorpheniramine maleate].

A high performance liquid chromatographic (HPLC) method was developed for the determination of chlorpheniramine (I) in the plasma. By this method, 1 ng of I could be measured. Plasma levels of I were determined by the HPLC method after oral administration of d-chlorpheniramine maleate (II) or l-chlorpheniramine maleate (III) to healthy subjects and dogs. Plasma levels of I brought about by oral administration of II were evidently higher than those by III both in humans and dogs. On the other hand, there was no difference in plasma levels of I when II or III was injected intravenously into dogs. Therefore, it was considered that the discrepancy in plasma levels of I after oral administration of II and III to dogs was neither due to a difference in elimination rate nor a distribution volume but rather in first-pass effect in absorption process. The result observed in the human study could be also explained in the same way as that in dogs.

Administration, Oral↗
PubMed1989

Reinforcement of the anastomosis between the fragile arterial vessel and the prosthetic graft. A headband method.

A new method of anastomosis was devised, intended for the reinforcement of the anastomosed area between the fragile vessel of the patient and the prosthetic graft in cardiovascular surgery. This method, which may be called a headband method, consists of suturing a small prosthetic graft wrapping the anastomosed area together with the arterial vessel in the manner of a headband. Fourteen cases have been evaluated at follow-up periods ranging from 24 to 40 months. All cases proved successful without noteworthy complications.

Anastomosis, Surgical↗
PubMed1989

[Factors affecting the setting time of zinc oxide-eugenol impression materials--the influence of humidity and temperature to the reaction velocity].

Zinc oxide-eugenol paste are widely used in clinical dentistry, principally for impression of non-undercut edentulous ridges, or bite taking materials. However it has been realized by those who use these paste that different products, direction for mixing, or different conditions for mixing, have different characteristics. An experiment have been made to observe the influence of different conditions for mixing to the setting time. Zinc oxide-eugenol impression pastes were mixed in accordance with the manufacturer's instruction when supplied. The condition for mixing was at temperature of 15 +/- 1, 20 +/- 1, 25 +/- 1, 30 +/- 1 degrees C and at humidity of 40 +/- 5, 70 +/- 5, 90 +/- 5%. The setting time (a initial setting time, a final setting time) was defined in the A.D.A. specification No. 16. The following results were obtained. 1. A higher temperature and humidity shortened the initial setting time of all paste. 2. A higher temperature and humidity shortened slightly the time interval between a initial and a final setting time of all paste. 3. In clinical use, sample C is better than other ones, so that a setting time of the sample is property for impression making.

Dental Impression Materials↗
PubMed1989

Cross-reactivity between human and canine helper and suppressor T cell antigens using monoclonal antibodies RPA-T4 and HuLy-m8.

The murine monoclonal antibodies RPA-T4 and HuLy-m8, specific for a framework determinant of human helper/inducer and suppressor/cytotoxic T cell antigens, cross-reacted with canine cell membrane molecules recognizing a biomolecular complex (50,000 to 55,000 daltons) similar to that described in humans. We investigated the distribution of these helper and suppressor T cell-like antigens on canine peripheral blood lymphocytes. With complement-mediated lymphocytotoxicity, 34% and 35% of the canine lymphocytes expressed the helper T cell-like antigens and the suppressor-like T cell antigens, respectively. When the lymphocytes were treated with RPA-T4 and HuLy-m8, the respective helper and suppressor function was significantly inhibited.

Animals↗
PubMed1989

[Two-chambered right ventricle in an elderly patient with anoxic spells].

A 53-year-old woman with two-chambered right ventricle and ventricular septal defect (VSD) was treated by VSD closure and resection of the abnormal muscle bundle within the right ventricle. The patient remained asymptomatic only with a heart murmur until the age of 40. Then she became to get tired more easily and presented dyspnea on minimal exercise. And recently, she suffered from cyanosis with anoxic spells, which finally led her to our clinic. Cardiac catheterization showed a high pressure chamber of 110 mmHg and a low pressure chamber of 27 mmHg in the right ventricle; a pressure gradient being 83 mmHg in the right ventricle with bidirectional interventricular shunt. This disorder is rarely found in elderly patients and the natural history for patients who remain asymptomatic are still unknown. To the best of our knowledge, this is the first elderly patient to develop anoxic spells like tetralogy of Fallot and treated surgically. The case is presented here, together with a review of the literature.

Female↗