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Biomedical subjects

H Hosaka

Publications and source records attributed to H Hosaka.

At least 55 records · Page 3Linked to original sources
PubMed1997

A comparison of body surface Laplacian and potential maps during paced ventricular activation.

The objective of this study is to evaluate the spatial resolution of body surface Laplacian maps (BSLMs) in localizing ventricular electrical activity by means of computer simulation. A 3-D computer heart-torso model was used to simulate cardiac electrical activity and the body surface maps. A two-site pacing protocol was used to generate two simultaneously activated myocardial events on the anterior epicardial wall and the anterior endocardial wall. Following the pacing, the BSLMs and the body surface potential maps (BSPMs) were calculated and compared with the known activation pattern. As a result, the BSLMs showed superior resolution than the BSPMs for localized initial ventricular activity. In summary, the present study suggests that body surface Laplacian mapping may provide a useful methodology for the clinical diagnosis of cardiac electrical abnormalities.

Body Surface Potential Mapping↗
PubMed1996

Outcome of arthrocentesis for temporomandibular joint with closed lock at 3 years follow-up.

OBJECTIVE: The aim of this study was to evaluate the intermediate term results of arthrocentesis for the management of temporomandibular joint closed lock. STUDY DESIGN: Twenty consecutive patients with closed locking of their temporomandibular joint were treated by arthrocentesis. All patients rated their pain level on a visual analogue scale, and completed pain, jaw dysfunction, and daily activity questionnaires before, 6 months, and 3 years after the procedure. The patients' jaw opening was also scaled. Preoperative and postoperative differences of the data were analyzed statistically. The success rate was also calculated according to our success criteria. RESULTS: The success rate was 70% at 6 months follow-up; it increased to 78.9% over the 3 years of follow-up. All posttreatment scores showed significant improvements in efficacy. CONCLUSION: Arthrocentesis was considered as an effective minimally invasive surgical treatment for temporomandibular joint closed lock based when evaluated 3 years after the procedure.

Adult↗
PubMed1996

Small-vessel radiography in situ with monochromatic synchrotron radiation.

PURPOSE: To evaluate the usefulness of a radiographic system with monochromatic synchrotron radiation to depict small vessels and peripheral secretory ducts. MATERIALS AND METHODS: Radiography of various organs was tested in 14 anesthetized dogs and pancreatography was performed in an excised human pancreas by using the following system: monochromatic synchrotron radiation with an energy level just above the k absorption edge of iodine as an x-ray source and a high-definition TV system with a high-light-sensitivity image pick-up tube camera coupled with a fluorescent screen as a detector. RESULTS: This system allowed depiction of small vessels (diameter < 50-100 microns) of the heart (penetrating transmural artery), brain (perforating arteries that arise directly in the circle of Willis), and intestinal organs (vasa recta and their submucosal communications) and of small branches (down to the fifth order) of the pancreatic duct. CONCLUSION: The synchrotron radiation system may be useful for evaluating microcirculatory disorders and early-stage malignant tumors in various human organs.

Adult↗
PubMed1996

Indirect measurement of tidal volume by multi-lead electrocardiograms: effect of filtering, deep breath, lead and posture.

We examined a new method for estimating tidal volume from the electrocardiogram (ECG) in order to dispense with the need for sensors used exclusively for tidal volume measurement. The direction of the vector loop in the QRS complex (DVL) was defined as the direction of the diagonal line of the rectangle which circumscribed the vector loop obtained from two orthogonal leads. Two leads of the ECG were transformed into the orthogonal leads using Einthoven's triangle. The peak-to-peak change in the direction (the change in the DVL) was highly correlated with tidal volume. Low-pass filtering of the ECG produced a better correlation between tidal volume and the change in the DVL, when the cutoff frequency was set at 20-45 Hz. A tidal volume of less than 1.21 was correlated more highly with the change in the DVL than a tidal volume of more than 1.21 A combination of leads I and III produced the best correlation between tidal volume and the change in the DVL, compared with other combinations. The posture of the subject had some effects on the slope of the linear regression between tidal volume and the change in the DVL.

Electrocardiography↗
PubMed1995

Short-term treatment outcome study for the management of temporomandibular joint closed lock. A comparison of arthrocentesis to nonsurgical therapy and arthroscopic lysis and lavage.

OBJECTIVE: The aim of this study is to compare the clinical short-term results and efficacy of arthrocentesis with those of nonsurgical treatments and arthroscopic surgery for the management of temporomandibular joint closed lock. STUDY DESIGN: The three groups consisted of 63 consecutive patients treated nonsurgically, 20 patients treated with arthrocentesis, and 25 patients treated with arthroscopic surgery. All patients rated their pain level on a visual analogue scale and completed a pain, jaw dysfunction, and activity-limiting questionnaire before and 6 months after the procedure. Each patient's jaw opening was also scaled. The success rate of each procedure was calculated according to our success criteria. The clinical efficacy of each procedure was evaluated in successfully treated subgroups in which the between-group and within-group differences of the obtained data were statistically tested. RESULTS: The success rate was 55.6% in the nonsurgically treated group, 70% in the arthrocentesis group, and 91% in the arthroscopy group. With respect to efficacy, all posttreatment scores showed significant improvements in within-group differences, but no between-group differences were found between the arthrocentesis group and the other two groups. CONCLUSION: Arthrocentesis was considered as an intervening treatment modality between nonsurgical treatment and arthroscopic surgery on the basis of its short-term outcome. Although the treatment efficacy was comparable with arthroscopic surgery, this procedure was thought to be indicated for the patients with acute temporomandibular joint closed lock who were refractory to medication and mandibular manipulation rather than the alternative of arthroscopic surgery.

Activities of Daily Living↗
PubMed1995

Comparative simulation of excitation and body surface electrocardiogram with isotropic and anisotropic computer heart models.

Comparative simulations between isotropic and anisotropic computer heart models were conducted to study the effects of myocardial anisotropy on the excitation process of the heart and on body surface electrocardiogram. The isotropic heart model includes atria, ventricles, and a special conduction system, and is electrophysiologically specified by parameters relative to action potential, conduction velocity, automaticity, and pacing. The anisotropic heart model was created by incorporating rotating fiber directions into the ventricles of the isotropic heart model. The orientation of the myocardial fibers in the ventricles of the model was gradually rotated counterclockwise from the epicardial layer to the endocardial layer for a total rotation of 90 degrees. The anisotropy of conduction velocity and intracellular electric conductivity was included in the simulation. Comparative simulations of the normal heart, LBBB, and RBBB showed no significant differences between the two models in the excitation processes of the whole heart or in the body surface electrocardiograms. However, it was easier to induce ventricular fibrillation in the anisotropic model than in the isotropic model. The comparative simulation is useful for investigating the effects of myocardial anisotropy at the whole heart level and for evaluating limitations of the isotropic heart model.

Action Potentials↗
PubMed1995

[Pulmonary infarct hardly differentiated from lung cancer--a case report].

A 64-year-old woman experienced high grade fever, chest pain, and hemosputum. She was admitted to a hospital for evaluation of the infiltrate on an chest X-ray. She was diagnosed as having lung cancer by sputum cytology and transferred to our hospital for operation. The tumor was obscure on palpation during thoractomy, but malignancy could not be ruled out based on analysis of frozen sections. Therefore, a right lower lobectomy and mediastinal lymph node dissection were performed. Pulmonary infarct was not suspected until thrombi were observed in the dissected pulmonary artery. Urokinase and heparin were intravenously administered soon after the operation, but the patient died of pulmonary thromboembolism of the sixth postoperative day. Examination of the operative specimen revealed pulmonary thromboembolism with infarction and no evidence of malignancy. Atypical cells observed in sputum cytology seemed to be derived from basal cell hyperplasia in the area of infarction. Type II alveolar epithelial cell hyperplasia was observed in the periphery of the infarction. These findings seemed to make accurate analysis of frozen sections difficult. An increasing number of cases of pulmonary thromboembolism is being reported in Japan. Therefore, pulmonary infarct with false positive cytology may be encountered more frequently in the future.

Diagnosis, Differential↗
PubMed1995

An experimental study on home health care support information system construction.

The need for home health care has been increasing in Japan and the expectation is to apply advanced technology to home health care in order to promote it. We already studied the development of a home care support information system using a personal computer and a telephone set with multifunction. In the present study a new system using a new telephone terminal was developed in order to increase flexibility. To work out the concrete social system in the near future, a model of a PHD (Personal Health Data) management system was constructed and tested. Experimental studies were conducted by physicians and public health nurses. The model system would be useful for daily monitoring of home patients in the chronic stage of a disease and for dealing with their emergency states.

Aged↗
PubMed1994

Sequence-specific cleavage of oligoribonucleotide capable of forming a stem and loop structure.

The precursor of an RNA molecule from T4-infected Escherichia coli cells (p2Sp1 RNA) has the capacity to cleave itself at specific positions ((UpA (137-138) and CpA (170-171)) within a possible loop and stem structure. This specific cleavage requires at least a monovalent cation and nonionic detergents. To confirm that the sequence-specific cleavage occurs autolytically, we studied the selective hydrolysis of RNA using a chemically synthesized 13-mer (GUUUCGUACAAAC) having sequences corresponding to G131-C143 of p2Sp1 RNA. The cleavage occurred at two identical sites (UpA and CpA) of a hairpin loop under physiological conditions and was affected by monovalent or divalent metals, nonionic detergent, salt, pH, and temperature. The hairpin loop domain and specific sequences are necessary for the cleavage of RNA 13-mer (GUUUCGUACAAAC).

Base Sequence↗
PubMed1994

Characterization of the secondary structure of an oligonucleotide corresponding to the autocleavage site of a precursor RNA from bacteriophage T4.

We studied the secondary structure of an RNA fragment (GUUUCGUACAAAC) (R1) having the sequence corresponding to the self-cleavage domain in a precursor RNA molecule from bacteriophage T4 infected Escherichia coli cells (p2Sp1 RNA). We synthesized an oligoribonucleotide (CAAACGUACAAAC) (R3) which contained the sequence (CGUACA) proposed for the p2Sp1 RNA self-cleavage site but did not form the hairpin loop structure. The self-cleavage ability of the single stranded RNA (R3) is significantly lower than that of R1. We have also designed a modified RNA fragment (R2), which contained a noncleavable RNA with 2'-O-methylcytidine or 2-O-methyluridine. R3 did not exhibit cleavage. To further investigate the structural requirements in the cleavage reaction, we synthesized mutant RNAs which contained different bases within consensus sequences and the cleavage sites were tested for self-cleavage. Guanosine and adenosine 3'-phosphates seemed not to be susceptible to transesterification at the cleavage site. The data from native gel electrophoresis, the CD spectra and the Tm suggested that the hairpin structure is necessary for the cleavage.

Bacteriophage T4↗
PubMed1994

Specificity of priming reaction of HIV-1 reverse transcriptase, 2'-OH or 3'-OH.

It has not been unambiguously demonstrated whether the priming reaction of human immunodeficiency virus, type 1 (HIV-1) cDNA synthesis initiates with either the 2'-OH or 3'-OH group of the 3'-terminal adenosine residue of tRNA(Lys-3). In this report, we synthesized tRNA(Lys-3) of which the 3'-terminal adenosine residue lacks either a 2'-OH or 3'-OH. These tRNA molecules were used for the HIV-1 cDNA-priming reaction in a cell-free system consisting of a 141-base RNA template and purified HIV-1 reverse transcriptase. It was found that under the conditions used, the tRNA containing the 2'-deoxyadenosine was able to initiate the cDNA synthesis, while the tRNA with the 3'-deoxyadenosine was not. The results show that retroviral reverse transcriptase specifically primes cDNA synthesis from the 3'-OH group. This is in contrast to bacterial reverse transcriptase, which initiates cDNA synthesis from the 2'-OH group of an internal guanosine residue of a template RNA.

Base Sequence↗
PubMed1994

Preventive equipment for urinary incontinence: a device employing lower abdominal impendance changes.

The object of this work was to develop a monitoring device for measuring the volume of urine in the bladder to signal, in advance, the need to urinate and thus help prevent urinary incontinence. A high-frequency electric current of 50 KHz transmitter was applied to a pair of terminals placed on the surface of a human body. The constant current was 2mA (p-p). A pair of voltage electrodes was placed in the path of the electric current to pick up high-frequency voltage signals. The best position for current electrodes was found to be on the surface of both femoral joints. Positioning the voltage electrode above the bladder on the lower abdomen was most efficient for detecting the volume of urine. New current electrodes sutured onto underpants were fitted on the surface above the femoral joints, which did not shift in the case of movement by the subjects. The reproducibility and stability were remarkably good with this electrode. The alarm level which foretold both maximum storage volume and maximum desire to void was examined. After that, when the alarm level was set within the range of impedance charge, 60% to 70%, the possibility of prediction of urination exists.

Clothing↗
PubMed1993

A study on the development of a filing system for funduscopic images with a personal computer for Twin AMHTS.

A filing system for ocular funduscopic image data was developed by using a personal computer for the Twin AMHTS. The development of the system was tried as one of the data transfer system including image data between two similar AMHTSs named the Twin AMHTS through the information network system. The filing system is capable of storing 26782 data of ophthalmoscopic pictures with a data compression mode by using a magneto-optical disk (MOD) whose storage capacity of both sides is 616 MB. It takes no long time for retrieval and display of the image data in the filing system. Good quality of compression and decompression obtained and reproducibility of the ocular fundus picture is favorable regardless of normal or abnormal cases. As a result, it is suggested that the developed system has practical utility although it requires more improvement.

Computer Communication Networks↗
PubMed1993

Arthroscopic punch for definitive diagnosis of synovial chondromatosis of the temporomandibular joint. Case report and pathology review.

Synovial chondromatosis is characterized as a benign monoarticular condition with metaplastic cartilaginous nodules that develop within the synovial membrane of articulating joints. In addition to a pathology literature review, this article describes an unusual case of temporomandibular synovial chondromatosis that was sufficiently expansile to displace the condyle, which created not only a posterior occlusal apertognathia, but unusual articular bony fossa and eminentia erosions. An arthroscopic approach for definitive diagnostic punch biopsy and surgical approach is described and presented along with preoperative computerized tomograph, magnetic resonance imaging, and tomographic diagnostic images, as well as 3-year follow-up clinical and radiographic findings. Most interestingly, the arthroscopic examination and biopsy proved to be the most useful method to establish a definitive diagnosis of synovial membrane chondromatosis within the temporomandibular joint region for this patient.

Arthroscopy↗
PubMed1993

In vivo observation of subendocardial microvessels of the beating porcine heart using a needle-probe videomicroscope with a CCD camera.

We developed a portable needle-probe videomicroscope with a charge-coupled device (CCD) camera to visualize the subendocardial microcirculation. In 12 open-chest anesthetized pigs, the sheathed needle probe with a doughnut-shaped balloon and a microtube for flushing away the intervening blood was introduced into the left ventricle through an incision in the left atrial appendage via the mitral valve. Images of the subendocardial microcirculation of the beating heart magnified by 200 or 400 on a 15-in. monitor were obtained. The phasic diameter change in subendocardial arterioles during cardiac cycle was from 114 +/- 46 microns (mean +/- SD) in end diastole to 84 +/- 26 microns in end systole (p < 0.001, n = 13, ratio of change = 24%) and that in venules from 134 +/- 60 microns to 109 +/- 45 microns (p < 0.001, n = 15, ratio of change = 17%). In contrast, the diameter of subepicardial arterioles was almost unchanged (2% decrease, n = 5, p < 0.01), and the venular diameter increased by 19% (n = 8, p < 0.001) from end diastole to end systole. Partial kinking and/or pinching of vessels was observed in some segments of subendocardial arterioles and venules. The percentage of systolic decrease in the diameter from diastole in the larger (> 100 microns) subendocardial arterioles and venules was greater than smaller (50-100 microns) vessels (both p < 0.05). In conclusion, using a newly developed microscope system, we were able to observe the subendocardial vessels in diastole and systole.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗