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Biomedical subjects

M Kono

Publications and source records attributed to M Kono.

At least 127 records · Page 7Linked to original sources
PubMed1995

[Evaluation of photon-counting X-ray radiography for the detection of pulmonary nodule: a preliminary report on experimental and clinical studies].

To evaluate the utility of photon counting X-ray radiography (quantum radiography: QR) for the detection of pulmonary nodules, experimental and clinical studies were performed in comparison with conventional X-ray (CXR). In the experimental study, spatial resolution was analyzed by using the micro-chart method. The simulated nodule detection study was performed by using a chest phantom. The results were evaluated by means of ROC analysis. In the clinical study, both images of CXR and QR were evaluated in a case of metastatic lung tumor. In the experimental study, the spatial resolution of QR was 200 microns. QR was superior to CXR in detecting simulated nodules in all areas. In clinical cases, QR was superior to CXR in depicting not only normal structures but also retrocardiac and retrodiaphragmatic pulmonary nodules.

Carcinoma, Renal Cell↗
PubMed1995

[A case of sudden death during postoperative Holter ECG examination in a patient who experienced intraoperative cardiac arrest].

We report a case of postoperative sudden death during Holter-ECG examination in a 62-yr-old male, who experienced intraoperative cardiac arrest possibly due to myocardial ischemia. Although the patient recovered from intraoperative event without any neurological sequelae, he suffered from spontaneous ventricular tachycardia following mild ST segment depression that led to cardiac arrest on the 58th postoperative day. Precise mechanism of sudden death was not clear because coronary angiography or autopsy was not performed. However, the postoperative Holter-ECG revealed frequent episodes of silent 0.5-1.0 mm ST segment depression during tachycardia which had not been observed in the preoperative 12-lead ECG. Thus a likely explanation would be that the patient had the undetected coronary artery disease with frequent episodes of silent ischemia and finally was led to the fatal arrhythmia. In this case, so called "stunned myocardium" following repeated silent ischemia may have also contributed to the life-threatening arrhythmias. This case suggests that even mild ST depression might lead to life-threatening arrhythmias in the patients with silent ischemia. Adequate preoperative evaluation and careful perioperative observation are necessary for these patients.

Death, Sudden, Cardiac↗
PubMed1995

[A case of inspiratory unidirectional value malfunction detected by an abnormal capnogram pattern].

We report a case of substantial rebreathing which occurred during the thoracoscopic bulla resection despite a normal FICO2 reading on capnogram. Early detection of inspiratory unidirectional valve malfunction as the cause of the rebreathing was only possible by careful observation of the capnogram pattern. During the course of one lung anesthesia, a rising end-tidal CO2 concentration (FETCO2) and a change in the pattern of the capnogram were observed. However, the lowest FICO2 value in the late phase of inspiration stayed below the alarm limit setting of rebreathing. For this reason, the capnograph failed to identify the beginning of inspiration and perceived the high FICO2 value in early inspiration as part of expiratory plateau. In case of the inspiratory valve malfunction, it is possible that analysis of the capnogram reveals underestimated FICO2.

Adolescent↗
PubMed1995

[An opinion regarding diagnostic radiology in new century].

I. Technology of diagnostic radiology of the chest on next century I received and discussed concerning following subjects: 1) Dose analogue images remain on next century? 2) Progress and quality of digital images. 3) Expectation of progress of CT, MR and RI on the chest. 4) Application of monochromatic X-ray for the diagnostic imaging. For the radiologists, it is very important to assess the clinical usefulness of each diagnostic modality and form consensus development annually. II. Radiologist in the next century In accordance with the progress of technology of diagnostic radiology, it is very important to know what radiologists should do in the next century. Many referring physicians may perform not only the X-ray examinations but also therapy by themselves to ensure quality and save time from the view point of patient's benefit. Besides diagnostic imaging technologies are very attractive to them. From this point of view, radiologist should see patients and grasp the clinical data of the patients and, of course, interpret diagnostic images which were ordered by themselves. And if possible, they should treat and take care the patients. To survive in the next century, radiologist must focus on an clinical relevance and subspecialization, either by organ group or by technology. In my opinion, organ group specialization seems more useful than subspecialization according to technologies. It is considered to be a survival tactics in next century that we radiologists should band together.

Forecasting↗
PubMed1995

The origin of the antiseptic-resistance gene ebr in Staphylococcus aureus.

The antiseptic-resistance gene ebr was detected not only in resistant strains of Staphylococcus aureus but also in sensitive strains of S. aureus, in coagulase-negative staphylococcal strains and in enterococcal strains by means of the polymerase chain reaction. The nucleotide sequence of the amplified DNA fragment of the ebr gene from a sensitive strain and that of the previously reported ebr gene were identical. It seems likely that antiseptic-resistant cells result from an increase in the copy number of a gene whose normal function is to remove toxic substances from normal sensitive cells of staphylococci and enterococci.

Anti-Infective Agents, Local↗
PubMed1994

[Experimental and clinical studies on utility of advanced multiple-beam equalization radiography for the diagnosis of pulmonary mass lesions].

The thorax has a wide dynamic range from low (lung fields) to high X-ray absorption (mediastinum, retrocardiac and retrodiaphragmatic areas). The conventional screen/film system cannot visualize each area of the thorax with good contrast on a single sheet of film with the wide latitude. To solve this problem, advanced multiple-beam equalization radiography (AMBER), a type of scanning equalization radiography, has been developed. The present studies were designed to evaluate the usefulness of AMBER for the chest from the experimental and clinical aspects. In the experimental study, an imaging technology assessment of density and contrast properties and a phantom study for detecting a simulated pulmonary nodule were carried out. In the clinical study, visualization of the normal structures and abnormal shadows in chest radiographs was assessed. X-ray findings in the AMBER films were compared with those of conventional chest radiographs using the screen/film system. In the analysis of density and contrast properties, AMBER showed more favorable contrast properties than the conventional system, regardless of background density. In the phantom study, the detectability of the nodule in the retrocardiac or retrodiaphragmatic region in an AMBER film was superior to that of the conventional system, and there was no reduction in detectability in other regions of the peripheral lung field. In the clinical assessment, AMBER was excellent for visualization of the mediastinum and the normal structures and lesions in the retrocardiac and retrodiaphragmatic areas. AMBER can be concluded to be excellent in visualizing not only the high absorption area, which is difficult to observe with the conventional system, but also the low absorption area.

Humans↗
PubMed1994

Synthesis and antitumor activity of novel mitomycin derivatives containing functional groups at the C-6-methyl position.

A series of C-6-substituted methyl mitomycins was synthesized and evaluated for anticellular and antitumor activities. These novel compounds were prepared by Michael addition of various alcohols or thiols to 6-demethyl-7,7-(ethylenedioxy)-6,7-dihydro-6-methylidenemitosanes followed by treatment with NH3 or MeOH/K2CO3. Most compounds were potent against HeLa S3, and some of them showed superior activity to that of mitomycin C (MMC) against P388 leukemia and sarcoma 180 in mice. In addition, some compounds exhibited remarkable activity against MMC-resistant P388 in mice. FAB-MS spectra of these mitomycin derivatives showed the elimination of the C-6-methyl substituents from the mitomycin skeletons to form quinonemethides. Interestingly, treatment of 6-demethyl-6-[[(2-pyrimidinyl)thio]methyl ]mitomycin C (12v) with diethylamine afforded 6-demethyl-6-[(diethylamino)methyl]mitomycin C (31) in good yield. These results suggested that the C-6-substituted methyl mitomycins would have different biological character from that of MMC.

Animals↗
PubMed1994

Synthesis and antitumor activity of novel 6-alkyl-6-demethylmitomycins.

A series of 6-alkyl-6-demethylmitomycins (1-5) was synthesized and evaluated for anticellular and antitumor activities. These novel compounds were prepared by Michael addition of various carbanion species to 6-demethyl-7, 7-(ethylenedioxy)-6, 7-dihydro-6-methylidenemitosane (6 and 9) followed by treatment with NH3 or MeOH/K2CO3. Alkylation at the C-6 position of 6-demethyl-6-selenide (7) was also useful for the alternative synthesis of 6-alkyl-6-demethylmitomycins. The antitumor activity of these derivatives was evaluated, and 6-demethyl-6-ethylmitomycin A (2a) was found to exhibit excellent activity against S-180 solid tumor in mice. The structure-activity relationship is also discussed.

Animals↗
PubMed1994

[CT evaluation of extravascular perfusion of contrast medium and its potential to a new method of diagnosis: an experimental study using macro, micro-molecular contrast media].

To evaluate the dynamics of extravascular perfusion, dynamic CT with two different molecular sized contrast media was performed on VX2 tumor of rabbit. The first dynamic CT was performed with a bolus injection of iopamidol (IP:120 mgI/ml, 5 ml). After ascertaining that the tumor attenuation had returned to the pre-contrast level, the second dynamic CT was performed on the same slice with bolus injection of iodoethylated starch (IES:120 mgI/ml). The time-density (T-D) curves of the same tumor area on the images obtained by two contrast media were compared. The T-D curve with IP showed definitely higher level than that with IES. This occurrence can be explained that IP, 13 A in size, has higher permeability distributing not only in the intravascular space, but also into the extravascular space. On the other hand, IES, 200 A in size, will stay mostly in the intravascular space. From this, we consider that the attenuation difference between the two curves will be an indicator for the dynamics of extravascular perfusion, suggesting to become a new method for CT diagnosis.

Animals↗
PubMed1994

[Experimental study on vascular permeability and hemodynamics of nonionic dimeric contrast media (Iotrolan): a comparison to nonionic monomer on dynamic CT and angiography].

The difference of vascular permeability and hemodynamics between Iotrolan and Iopamidol was experimentally studied on dynamic CT and angiography. A hemodialyzer with 60 A pores were applied as a phantom of a target organ with capillaries and extravascular space. Dynamic CT scans and DSA of the phantom were performed with injection of each contrast medium and time-density curves obtained from several regions of interest were compared. The dynamic CT scans performed at 40 seconds after the completion of injection, showed that Iopamidol was mostly distributed at the site of inlet, while Iotrolan was mostly at the center of the phantom. Time-density curves on DSA with Iotrolan revealed lower and shorter peak density and time than did Iopamidol. In conclusion, Iotrolan has lower permeability than that of Iopamidol because of its larger molecular size. Iotrolan has slower flow through catheters and capillaries than that of Iopamidol because of its higher viscosity. One should be aware the difference between the two contrast media and be careful to the analysis of time-density curves of dynamic CT and DSA.

Angiography, Digital Subtraction↗
PubMed1994

Cervicothoracic vagal neurilemoma: report of a case.

We report herein the rare case of a 45-year-old man with a cervicomediastinal neurilemoma of the vagus nerve. The tumor was 160 x 40 x 35 mm in size and extended from the angle of the right mandible to the aortic arch. Despite this being the largest such tumor ever reported, the patient presented without any symptoms. Thus, although vagal neurilemoma is uncommon, it should nevertheless be included in the differential diagnosis of any asymptomatic mass along the vagus nerve. In the evaluation of such masses, magnetic resonance imaging can provide useful information regarding not only the location, but also the nature of the lesion.

Cranial Nerve Neoplasms↗
PubMed1994

Detection and cloning of human papillomavirus DNA associated with recurrent respiratory papillomatosis in Thailand.

Recurrent respiratory papillomatosis (RRP) is highly prevalent in Thailand. In this study, we examined the presence of human papillomavirus (HPV) DNA in 25 RRP patients in Thailand by means of dot blot analysis and/or polymerase chain reaction. Eighty-four percent (21/25) of cases and 4% (1/25) of cases were positive for HPV-11 DNA and HPV-6 DNA, respectively. Three cases (3/25) were negative for all of the examined HPV types. No cases were positive for HPV-16 or 18. Furthermore, we isolated the recombinant HPV-11 DNA clone from a genomic library constructed with the DNA of RRP tissue. The restriction map of the cloned HPV DNA was identical with the map of known HPV-11 DNA. These results suggest at least that no specific HPV type or subtype is likely to be associated with RRP in Thailand.

Base Sequence↗
PubMed1994

Eating Attitudes Test in Japan.

A Japanese version of the Eating Attitudes Test (EAT) was developed and validated using a group of anorectics and Japanese female controls. Its sensitivity was considered to be low for anorectics, especially for the fasting type anorectics. A cross-cultural comparison of the EAT scores of anorectics showed some significant differences among those found in Japan, Canada and Germany. A survey of eating disorders among 286 Japanese female students was carried out with a Japanese EAT. Three cases of bulimia nervosa were identified in this survey, although no clear case of anorexia nervosa could be identified. The EAT seemed to be useful to screen cases of bulimia nervosa and sensitive to distinguish abnormal eating attitudes among the young females in Japan.

Adult↗
PubMed1994

pH dependence of the absorption spectra and photochemical transformations of the archaerhodopsins.

Two strains of archaebacteria have been found to contain light-driven proton pumping pigments analogous to bacteriorhodopsin (bR) in Halobacterium salinarium. These proteins are called archaerhodopsin-1 (aR-1) and archaerhodopsin-2 (aR-2). Their high degree of sequence identity with bR within the putative proton channel enables us to draw some conclusions about the roles of regions where differences in amino acids exist, and in particular the surface residues, on the structure and function of retinal-based proton pumps. We have characterized the spectral and photochemical properties of these two proteins and compared them to the corresponding properties of bR. While there are some differences in absorbance maxima and kinetics of the photocycle, most of the properties of aR-1 and aR-2 are similar to those of bR. The most striking differences of these proteins with bR are the lack of an alkaline-induced red-shifted absorption species and a dramatic (apparent) decrease in the light-induced transient proton release. In membrane sheet suspensions of aR-1 at 0.15 M KCl, the order of proton release and uptake appears opposite that of bR, in which proton release precedes uptake. The nature of this behavior appears to be due to differences in the amino acid sequence at the surfaces of the proteins. In particular, the residue corresponding to the lysine at position 129 of the extracellular loop region of bR is a histidine in aR-1 and could regulate the efficient release of protons into solution in bR.

Archaeal Proteins↗