A total of 1,355 cases of tularemia observed between 1924 and 1987 in Japan were viewed on the basis of clinical manifestations and the results were compared with those in the United States. The incubation period varied from one day to over one month. In 75.5% of cases, the symptoms of illness appeared within seven days with the peak on the third day. A sudden onset of flu-like symptoms was generally observed, and 92% of cases was followed by regional lymph node swelling which mostly appeared in axillary and cubital regions. They were observed predominantly at the left rather than the right side. In contrast with the cases in the United States, the number of cases of ulceroglandular type in Japan was only one third of those of glandular type. None of the pleuropulmonary cases or fatal tularemia have been reported in Japan. The number of oropharyngeal cases has remarkably increased after World War II, and is still on the rise, presumably because of the change of dietary habits in Japan. All these characteristics of Japanese tularemia are assumed to be caused by low virulence of Japanese strains of Francisella tularensis.

Axilla↗

PubMedDate not supplied

Baylor multipurpose circulatory support system for short- to long-term use.

A multipurpose circulatory support system has been developed as both a temporary and permanent device in total artificial hearts (TAHs) and ventricular assist devices (VADs). The multipurpose concept was derived from the development of a totally implantable electromechanical, one-piece TAH. The blood pump is pneumatically driven in short-term use and is electromechanically driven in long-term or permanent use. Both TAH and VAD versions consist of the same components, except for the actuation mechanism. The common components are a compact pumping chamber with the same configuration, a blood contacting surface biolized with gelatin, a pusher-plate, a Hexsyn rubber diaphragm (University of Akron, Akron, OH) and bovine pericardial valves. Both TAHs and VADs have 63 ml of stroke volume, and the VADs are compact compared with other available investigational device exemption devices. Currently, 1 week survival has been achieved using the electromechanical TAH and 2 week survival using the electromechanimcal VAD without anticoagulation. Results suggest that the currently developed system could be applied in varied patients as a temporary device after cardiotomy, a long-term device for bridge to transplantation, or a permanent device for end-stage heart disease.

Assisted Circulation↗

PubMedDate not supplied

The Baylor total artificial heart. Flow visualization studies.

To analyze the flow patterns of the left blood chamber of the Baylor total artificial heart (TAH) and to evaluate influences of the inflow valve angle to the flow patterns, flow visualization studies were performed. The inflow valve angle of the left housing was changed by 20 degrees orthogonal to the inflow tube, and comparison studies of the modified and unmodified models were made. For evaluating sectional flow patterns, a laser light was used, the clear transparent housing was scanned segmentally, and flow patterns were recorded on high contrast film for measuring flow velocities. A signal was used that synchronized the timing of the camera shutter to the pusher-plate movement signal. With the modified 20 degree inflow valve direction, there were better closing characteristics of the inflow valve leaflets. At the same time, we could successfully reduce the vortex formation at the inflow port, which may cause thrombus formation. We also have improved the washout during the diastolic phase in not only the bottom area, but in the entire pumping chamber. This flow visualization setup is simple and inexpensive. It is useful not only for validation of global flow patterns, but also for validation of local flow velocities of various blood pumps.

Biomedical Engineering↗

PubMedDate not supplied

Partial maze procedure is effective treatment for chronic atrial fibrillation associated with valve disease.

The maze procedure may be performed in combination with valve operations to treat chronic atrial fibrillation associated with valve dysfunction. Although we initially used the modified Cox maze III procedure, a more limited partial maze procedure is now preferred because the left atrium might be considered as the electrical impetues for atrial fibrillation. In this study we compared the results of 30 patients (group I) who underwent the full biatrial modified Cox maze III and 20 (group II) patients the partial maze procedure. While the rates of restored sinus rhythm were the same in both groups at 6-month follow-up (I: 83.3%, vs II: 80%), the following advantages were noted in the patients undergoing the partial maze procedure: shorter operative times, lesser elevations of creatine phosphokinase, lower rate of blood transfusion, lower rate of junctional rhythm soon after the operation, and a higher P wave in those patients with restored sinus rhythm. The effectiveness of the partial maze procedure seems equal to that of the biatrial modified Cox maze III procedure for atrial fibrillation associated with valve disease. The partial maze procedure is simple and less invasive, and thus might be applied more frequently as an additional procedure to valve operations without additional risk.

Aged↗

PubMedDate not supplied

A new method of preparing monocored water-loaded microcapsules using interfacial polymer deposition process.

A new method was proposed to prepare monocored water-loaded microcapsules with diameters of 50 microns or larger by making use of the process of interfacial polymer deposition. A solution of ethylcellulose or polystyrene in dichloromethane was added dropwise to an O/W emulsion in which n-hexane was dispersed as fine droplets in aqueous gelatin solution. Successive evaporation of dichloromethane at 40 degrees C and n-hexane at 80 degrees C gave monocored water-loaded ethylcellulose or polystyrene microcapsules. Monocored water-loaded ethylcellulose/polystyrene composite microcapsules were similarly prepared using mixed solutions of the two polymers in dichloromethane instead of ethylcellulose or polystyrene solution. When those mixed solutions which exhibit phase separation were used, the composite microcapsules obtained had a patchwork-like structure in which polystyrene-rich islands are dispersed in the ethylcellulose-rich sea.

Cellulose↗

PubMedDate not supplied

Development of a syngenic brain-tumor model resistant to chloroethyl-nitrosourea using a methylguanine DNA methyltransferase cDNA.

Chloroethyl-nitrosourea (CENU) is one of the most potent chemotherapeutic agents for brain tumors. However, acquired resistance to this drug has become a serious problem in the treatment of brain tumor patients. The main mechanism of the resistance is a recruitment of the O6-methylguanine-DNA- methyltransferase (MGMT) in tumor cells. Many approaches, including treatment with enzyme-depletions, antibodies, antisenses, and a ribozyme, have been reported to successfully overcome the resistance. In order to evaluate these approaches properly, we designed a syngenic rat brain-tumor model resistant to CENU. The 9L rat gliosarcoma cells were retrovirally transduced with MGMT cDNA and stereotactically implanted into the brain parenchyma. In this model, rats inoculated with resistant cells died significantly earlier than did rats with control cells after treatment with CENU. Because of the limited intracranial space, the animals presented a restricted survival. Since the survival was sensitive and reproducible, this system may have a role in the evaluation of approaches to drug-resistant brain-tumors.

Animals↗

PubMedDate not supplied

The Baylor-ABI electromechanical total artificial heart. Accelerated endurance testing.

To test the durability of each part or assembled component of the Baylor-ABI total artificial heart (TAH), the authors performed an endurance test under severe conditions. The TAH was immersed in a saline bath at 42 degrees C, which is 4-5 degrees C higher than normal body temperature. This is an accelerated endurance test because of the elevated temperatures. In this accelerated endurance test loop, the 42 degrees C heated saline was circulated not only in the pump but also outside the pump. During pumping, temperatures of the motor and outside surface of the centerpiece were continuously measured. This testing showed that during almost 4 months of pumping no electromechanical troubles were observed. Both inside (motor) and outside temperatures were stable and the differences in both temperatures were only 3-4 degrees C, demonstrating that heat generation is not a problem. The voltage and current required in this system remained constant, indicating stable and reliable performance. Based on these results, this pump is expected to run continuously over a long duration in a normal physiologic environment. This accelerated endurance test system is very suitable for estimating the influence of heat generation by the actuator of blood pumps. It is also quite useful in validating the durability of various cardiac prosthesis.

Heart, Artificial↗