[Modeling and simulation of contractile process of heart muscle (author's transl)].
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Biomedical subjects
Publications and source records attributed to K Akazawa.
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We recorded visual evoked potentials (VEPs) to checkerboard pattern-reversal stimulation in 109 normal subjects (51 males and 59 females; aged 19-84 years) in order to study the aging effect on the multiple channels of the visual system in humans. Transient VEPs to 3 check sizes (15', 30' and 50') were obtained by monocular stimulation. Two test conditions were employed: (1) a high luminance (180 cd/m2) and a low luminance (11 cd/m2) both with a fixed contrast (90%), and (2) a high contrast (85%) and a low contrast (10%) both at a fixed luminance (57 cd/m2). The major features of our results included: (1) the presence of a curvilinear relationship between P100 latency and age for all conditions, while the P100 amplitude did not show any such aging effect, (2) the age-latency function was similar between the two luminance conditions, while it was different between the two contrast conditions, and (3) the differential age effect on the P100 latency caused by changes in contrast depended on the check size. These results suggest that age-related changes in the human visual system are not uniform, but rather are different in the specific functional subdivisions. It is thus hypothesized that aging may differentially influence the separate channels of the human visual system.
We created a multimedia system to computerize past lectures using RealAudio software. Physicians, medical researchers and students can browse the contents of lecture slides and handouts with synchronous audio using the Internet. The audience can easily review the most interesting parts of lectures and medical students can listen to complete medical lectures from remote sites with narration and slide depiction, whenever convenient. We have created three multimedia programs; the memorial lecture of a professor's retirement, a new method of hand washing for surgical procedures and a lecture on medical informatics. The cost of this system and the results of the evaluation by medical students are described. The ease of using this application makes it a potentially valuable tool for clinicians and researchers.
The prognosis of 174 patients with cirrhosis during the 1980s (1981-89) was analysed. The estimated survival rates were 87.3% in 3 years and 68.5% in 5 years. During the follow-up period, 58 patients died: 20 of hepatocellular carcinoma (37.7%); 11 of hepatic failure (20.8%); eight of gastrointestinal bleeding (15.1%); and 14 of other causes (26.4%). Multivariate analysis revealed that serum albumin, indocyanine green retention rate at 15 min and white blood cell count were significantly associated with prognosis. The results were also compared to our previous study covering the 1970s (1971-80). The estimated survival rate was significantly improved compared to that during the 1970s (54.3% in 5 years, P < 0.001). In the 1980s, hepatic failure mortality significantly decreased (P < 0.01), and non-liver-related mortality significantly increased (P < 0.05). In summary, the prognosis of cirrhosis has improved in recent years, and changes of death cause and prognostic factors were observed. It was concluded that to evaluate the severity and prognosis of cirrhosis, new indices and appropriate classification were necessary.
Seven female patients with mild to moderate dementia of the Alzheimer type (DAT) were treated with long-term, low-dose estrogen replacement therapy (ERT) over a period of 5-45 months. Five of the 7 patients were cases who had responded well to short-term ERT with 1.25 mg/day of conjugated equine estrogens (CEE) for 6 weeks. The 7 patients from 56 to 77 years of age received 0.625 mg/day of CEE for 21 days, followed by a pause of 7 days. A 28-day cycle of low-dose ERT was performed repeatedly. In 4 cases, these patients received 5 mg/day of medroxyprogesterone acetate (MPA) during the last 10-12 days of estrogen treatment. Therapeutic efficacy of estrogen was evaluated by psychometric assessments such as the Mini-Mental State Examination (MMSE) and the Hasegawa Dementia Scale (HDS) and a behavior rating scale of the Gottfries-Bråne-Steen geriatric rating scale (GBS). The MMSE and HDS evaluations were performed principally once in 2-4 weeks. In 4 out of the 7 patients, the MMSE and HDS scores were elevated above the pretreatment levels during ERT. The termination of ERT resulted in a decrease in both scores. Furthermore, the GBS scores and daily activities of the same 4 patients were improved during ERT. In these 4 patients cognitive functions were markedly improved throughout the treatment period, while the other 2 patients responded moderately well and another patient did not respond at all. These observations suggest that long-term, low-dose ERT improves cognitive functions, dementia symptoms and daily activities in women with mild to moderate DAT.(ABSTRACT TRUNCATED AT 250 WORDS)
Serum carcinoembryonic antigen (CEA) levels were determined preoperatively in 221 patients with well-differentiated gastric cancer. The mean preoperative serum CEA level was 15.9 +/- 88.5 ng/ml (1.0-1,133.0 ng/ml) for all patients, and the incidence of an elevated CEA (> 5 ng/ml) was 11.8% (26/221). The CEA-positive patients had larger tumors, a more prominent serosal invasion, more frequent lymphatic and vascular involvement, less expansive tumor growth and higher rates of lymph node and hepatic metastases than did the CEA-negative patients. Thus, the CEA-positive patients had a more advanced stage of disease, and 61.5% underwent noncurative resection (vs. 11.3% in CEA-negative patients). The survival rate of the CEA-positive patients was lower than that of the CEA-negative ones (p < 0.01). As the multivariate analysis revealed the preoperative CEA level to be an independent prognostic factor for survival, an assay for this antigen prior to surgery is to be recommended.
We examined 52 children with advanced neuroblastoma who were diagnosed and treated during the past 7 years, and investigated the correlation between the degree of lymph node (LN) metastasis and the prognosis of neuroblastoma. In 8 of the 52 patients, distant LN metastasis was confirmed both radiographically and histologically. The urinary homovanillic acid (HVA) level was markedly elevated in these patients, and it was higher than that in patients with regional LN metastasis (p less than .05). The urinary vanillylmandelic acid (VMA) level and the VMA/HVA ratio were not significantly different between patients with regional and distant LN metastasis. None of the four examined patients with distant LN metastasis showed N-myc amplification of neuroblastoma tumors. An analysis of the survival rate in each patient group classified according to the degree of LN metastasis showed that the prognosis of the patients without LN metastasis or with distant LN metastasis tended to be better than that of patients with regional LN metastasis. Our results indicate that patients with distant LN metastasis may belong to a subclass with different biological features and a better prognosis than those of other groups.
An on-line system for electrocardiogram (ECG) interpretation using the Bonner program has been developed. The system consists of a telephone network, a process computer, a host computer, a computer interface and an electrocardiograph equipped with transmitting options. The signal acquisition program offered by IBM was modified so as to be equipped with the following functions: The technician can distinguish whether the process computer is ready or not, even if he is working in an examination room which is distant from the computer room. The data received by the process computer is transferred to the host computer in real time. In cases where the host computer is unable to receive the data, the process computer restarts transmission quickly after the host computer recovers the function of receiving. The host computer interprets transferred data in real-time by the Bonner program. The interpretation report is printed in real time on a remote printer. As the result of these modifications, a series of data processing operations may be executed without intermediary operators. The printed interpretation report begins to appear about ten seconds after completion of transmission.
The concept of PASK (Patient follow-up System of Kyushu University Hospital) has been innovated in order to manage clinical data of patients in the hospital-wide scope over long periods of time by using computers. PASK represents a collection of subsystems, each tuned to a specific disease. For the initial implementation, the subsystem for stomach cancer (STOMAC) was constructed according to the Cancer Center of Kyushu University Hospital project. STOMAC began to work in October 1984 and has proved effective. Using STOMAC, doctors in a clinical section can easily access patient data gained in another section. Besides providing a data reference function, STOMAC automatically gives alarms for abnormalities in clinical examination results, anti-tumor drug dosage, visitation cycles of patients, etc. The database and STOMAC programs are strongly standardized and easily applicable to another specific disease.
A database system was developed for storing and retrieving electrocardiogram (ECG) interpretations made by the Bonner program. One ECG record consists of the patient identification information, measurement matrix, and interpretive statements made by the program and by the reviewing cardiologist. The logical structure of the database is 3-level hierarchy. An ECG record is automatically inserted into the database when an ECG signal is analysed by the program. Stored ECG records can easily be retrieved using any parameter and qualifier for review, research and education. The physician can gather statistics on the parameters and qualifiers of the extracted ECG records using statistical program packages (BDMP, SCSS) and a decision support system (AS). Since the database management system is DL/I, the newly developed system can be transferred to various computers, and the relationships between the ECG findings and clinical records stored in the DL/I form can easily be studied.
We have developed a beat-to-beat calculator which can calculate in real-time the ratio of the diastolic pressure time index (DPTI), and the tension time index (TTI) as an index of the myocardial oxygen supply/demand balance. Physicians set up presumed value for the left ventricular endodiastolic pressure, a search area for the dicrotic notch, a threshold for the onset of the up-slope and the corresponding value of the calibration signal on the digital switches of the calculator. Next, the arterial pressure analog signal is input into the calculator. The calculator searches automatically for both the onset of the up-slope and the dicrotic notch. The arterial pressure curve is displayed beat-to-beat with the recognized onset and the dicrotic notch on the CRT to be confirmed by physicians. When physicians do not agree with the automatic recognition they can fit the automatic recognition to the observation. If the recognition of the onset is inadequate, the threshold can be re-adjusted to trigger the onset. If recognition of the dicrotic notch is inadequate, the physician can adjust the search-area. Therefore, physicians who operate the calculator can rely on the calculated DPTI/TTI. This calculator can continuously monitor the myocardial oxygen supply/demand balance in patients with acute myocardial infarction or just after open-heart surgery.
Myocardial infarction was produced in 29 anaesthetized mongrel dogs by a closed-chest coronary occlusion technique. A two-dimensional echocardiographic examination (2-D echo) was carried out just before occlusion and again 48 h after occlusion. Many cross-sectional images were recorded by a video-tape recorder. The applied site of the probe was fixed in an intercostal space and the direction of the ultrasonic beam was tilted stepwise from the basis to the apex. The animals were sacrificed at 49 hours after occlusion. The hearts were removed, quick frozen, sliced into radiating sections and stained with nitroblue tetrazolium (NBT). The outline of dyssynergy, including dyskinesis, akinesis or extreme hypokinesis, was traced with a tablet digitizer by two specialists. The three-dimensional image of dyssynergy in the left ventricular wall was reconstructed by a computer in spherical co-ordinates and assumed to be made of numerous triangular pyramids. The volume of dyssynergy was calculated quantitatively as the sum of volumes of these numerous triangular pyramids. The volume of dyssynergy seen in 2-D echo correlated well over a wide range with the volume of infarction determined by NBT staining.