Biomedical subjects

M Mikami

Publications and source records attributed to M Mikami.

167 records · Page 10Linked to original sources

PubMedDate not supplied

Evaluation of floating impeller phenomena in a gyro centrifugal pump.

The Gyro centrifugal pump, developed as a totally implantable artificial heart, was designed with a free impeller in which the rotational shaft (male bearing) of the impeller was completely separated from the female bearing. For this type of pump, it is very important to keep the proper magnet balance (impeller-magnet and actuator-magnet balance) to prevent thrombus formation or bearing wear. When the magnet balance is not proper, the impeller is jerked down into the bottom bearing. On the other hand, if magnet balance is proper, the impeller is lifted off the bottom of the pump housing within a certain range of pumping conditions. In this study, this floating phenomenon was investigated in detail. The floating phenomenon was proven by observation of the impeller behavior by means of a transparent acrylic pump. The impeller floating phenomenon was mapped on a pump performance curve. The impeller floating phenomenon is affected by the magnet-magnet coupling distance and the rotational speed of the impeller. To keep the proper magnet balance and to maintain the impeller floating phenomenon at the driving conditions of right and left pumps, the magnet-magnet coupling distance was altered by a spacer that was installed between the pump and actuator. It became clear that the same pump could handle different conditions (right and left ventricular assist) by changing the thickness of the spacer. When magnet balance is proper, the floating impeller phenomenon occurs automatically in response to the impeller revolution. This is called "the dynamic revolutions per minute suspension."

Centrifugation↗

PubMedDate not supplied

Malignant mixed müllerian tumor of primary mesenteric origin.

Malignant mixed müllerian tumor (MMMT) is a rare tumor. A literature search revealed very few reports on MMMT, especially those arising in the peritoneum. We recently encountered an MMMT of primary mesenteric origin associated with left fallopian tube cancer. There have been no previous reports about its occurrence in the mesentery. When cases of peritoneal MMMT were reviewed, the disease was found to be associated with synchronous or metachronous gynecologic tumors of müllerian duct origin (ie, ovarian tumors, primary serous carcinoma of the peritoneum, fallopian tube cancer, endometrial cancer, and adenocarcinoma of the cervix) in 12 out of 32 patients (37.5%). Peritoneal MMMT are frequently associated with gynecologic tumors.

Adenocarcinoma↗

PubMedDate not supplied

Bactericidal effect of levofloxacin on strains with equal susceptibility in an in vitro urinary bladder model.

The in vitro bactericidal effects of therapeutic concentrations of levofloxacin (LVFX) on clinical isolates of Pseudomonas aeruginosa and Enterococcus faecalis were assessed. Starting from 10(7) CFU/ml, the bacterial count was determined serially during the exposure to LVFX present at concentrations automatically simulated to its clinically achievable urinary levels at the recommended dosage (100 mg 3 times daily). An isolate of P. aeruginosa for which the MIC of LVFX was 16 microgram/ml was completely eradicated after 10 h of exposure to LVFX. On the other hand, 40 h of exposure to LVFX were required for complete eradication of an isolate of E. faecalis with equal susceptibility, although the bacterial count was rapidly reduced to 10(2) CFU/ml in the early phase of the exposure. It was concluded that LVFX exerts a more potent bactericidal effect on P. aeruginosa than on E. faecalis despite a similar susceptibility of these organisms to LVFX.

Anti-Infective Agents, Urinary↗

PubMedDate not supplied

Changes in susceptibility of Pseudomonas aeruginosa to gatifloxacin and carbapenem in an in vitro urinary bladder model.

To study the changes of bacterial susceptibility during exposure to antimicrobials, the respective minimal inhibitory concentrations (MICs) of 50 colonies from each of various bacterial test strains were determined in an experimental system using an in vitro urinary bladder model. The MICs of gatifloxacin and meropenem for Pseudomonas aeruginosa strains were not homogeneous before exposure to the drugs. The MICs of the strains examined reflected only that of their dominant population. When starting from 10(7)CFU/ml, the bacterial count was determined serially during exposure to gatifloxacin or meropenem in therapeutic urinary concentrations. The MIC of the less susceptible population of each strain was changed serially to a higher one. The more susceptible strains were eradicated before the change of the MIC. The bacteria originally consisted of strains having heterogeneous susceptibility to drugs, in which major strains had susceptibility expressed by the MIC and minor ones had a higher or lower MIC. This heterogeneity may be responsible for the change of susceptibility in strains after exposure to the drugs.

Anti-Infective Agents↗

PubMedDate not supplied

Recurrent Pneumocystis carinii pneumonia with long interval showing disparate radiographic findings.

A case of recurrent Pneumocystis carinii pneumonia with a long interval between episodes and each episode showing a different radiographic appearance is reported. The radiographic finding in the initial infectious episode was bilateral, patchy, alveolar infiltrate predominantly in the upper and middle lung zones and that in the second infectious episode, six and a half years later, showed bilateral interstitial infiltrate predominantly in the middle and lower lung zones. T cell immunity expressed by mitogen-induced T cell proliferation was clearly different in the two infectious episodes. These differences in radiographic appearance could be due, at least in part, to altered immunological states between the first and second infectious episodes.

Adult↗