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Biomedical subjects

K Doi

Publications and source records attributed to K Doi.

At least 289 records · Page 16Linked to original sources
PubMed1998

[Predictive factors for speech perception in patients with cochlear implant].

Cochlear implant therapy is an epoch-making advance in artificial sensory organ transplants, but the positive effects on speech perception vary. Quantification theory type I, a multivariate analysis, was used to determine predictive factors for speech perception in patients with cochlear implants. Fifty-one postlingual deaf adults (18 male and 33 female, mean age, 53.4, mean duration of deafness, 8.6 years) were tested for speech perception three or more months after a Nucleus 22 channels cochlear implant. The cause of deafness in nine patients was labyrinthitis, ototoxicity in five, meningitis in three and unknown in the remaining 34. Speech perception was measured by vowel, consonant and word recognition using a live voice, and monosyllable, word and sentence recognition using a videodisc. All tests were administered in a sound only condition. Results of the univariate analysis indicated that age at implantation was correlated with monosyllable recognition, and duration of deafness was correlated with live voice word recognition. Residual hearing and coding strategy were both correlated with all outcome measures. The multivariate analysis revealed that coding strategy, duration of deafness, residual hearing and the number of electrodes were significant predictors of live voice word recognition in that order.

Adolescent↗
PubMed1998

Efficacy of hydroquinone in the treatment of cutaneous hyperpigmentation in hairless descendants of Mexican hairless dogs (Xoloitzcuintli).

The skin of adult hairless dogs is clinically nonpigmented, clinically lightly pigmented, or clinically hyperpigmented (spotty pigmented). The pigment noted clinically is attributable to melanin granules in the epidermis. Spotty pigmentation in the skin of adult hairless dogs was treated by administration of the depigmenting agent (3% hydroquinone, HQ) for 1 month. Depigmenting effects were examined by use of three methods: skin color, dihydroxyphenylalanine (DOPA)-positive melanocyte count, and histologic evaluation. The treated skin of hairless dogs began to become depigmented after application of HQ for 1 week. After 1 month of treatment with HQ, depigmentation spread over a quarter of the body. The number of DOPA-positive melanocytes in the HQ-treated sites decreased to less than approximately a fifth of that before treatment. In HQ-treated skin, histologic staining by use of Fontana-Masson's (FM) method revealed complete absence of melanin pigment. These results suggested that hairless dogs should be a useful animal model for investigating the effects and cutaneous toxicity of depigmenting agents.

Animals↗
PubMed1998

[Clinical usefulness of scatter and attenuation correction for brain single photon emission computed tomography (SPECT) in pediatrics].

This investigation was undertaken to study clinical usefulness of scatter and attenuation correction (SAC) of brain SPECT in infants to compare the standard reconstruction (STD). The brain SPECT was performed in 31 patients with 19 epilepsy, 5 cerebro-vascular disease, 2 brain tumor, 3 meningitis, 1 hydrocephalus and psychosis (mean age 5.0 +/- 4.9 years old). Many patients was necessary to be injected sedatives for restraining body motion after Technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) was injected at the convulsion or rest. Brain SPECT data were acquired with triple detector gamma camera (GCA-9300 Toshiba Japan). These data were reconstructed by filtered backprojection after the raw data were corrected by triple energy windows method of scatter correction and Chang filtered method of attenuation correction. The same data was reconstructed by filtered backprojection without these corrections. Both SAC and STD SPECT images were analyzed by the visual interpretation. The uptake ratio of cerebral basal nuclei was calculated by the counts of the thalamus or lenticular nuclei divided by the cortex. All images of SAC method were excellent than that of STD method. The thalamic uptake ratio in SAC method was higher than that of STD method (1.22 +/- 0.09 > 0.87 +/- 0.22 p < 0.01). The lenticular nuclear uptake ratio in SAC method was higher than that of STD method (1.26 +/- 0.15 > 1.02 +/- 0.16 p < 0.01). Transmission scan is the most suitable method of absorption correction. But the transmission scan is not adequate for examination of children, because this scan needs a lot of time and the infants are exposed by the line source radioisotope. It was concluded that these scatter and absorption corrections were most suitable method for brain SPECT in pediatrics.

Adolescent↗
PubMed1998

[A case report of mycotic aneurysms of descending thoracic aorta].

A rare case of mycotic aneurysms of descending thoracic aorta is presented. A 63-year-old man was admitted with history of persistent high fever and loss of consciousness to our hospital. On admission, there were elevated WBC and CRP. Blood and spinal fluid cultures revealed growth of Streptococcus pneumonia. Despite of antibiotic therapy for meningitis and bacteremia, inflammatory sign continued, and new abnormal shadow appeared on chest X-ray. Chest CT and aortography showed two aneurysms of descending thoracic aorta. In an emergency operation, there was no abscess formation around the aneurysms. Aneurysms were excised en bloc without opening aneurysms followed by in situ Dacron tube graft replacement. The patient has been doing well without infection.

Aneurysm, Infected↗
PubMed1998

[Does dilatation of the sinotubular junction cause aortic regurgitation?: the use of the experimental model and preliminary result].

This study investigated the mechanism of aortic regurgitation caused by dilatation of the sinotubular junction. The canine model of dilatation of the sinotubular junction was used to observe coaptation of the aortic valve using direct imaging by endoscopy. Five adult mongrel dogs (body weight: 20-25 kg) were anesthetized and their hearts and thoracic aortas were extracted en bloc. Aortotomy was performed and an interrupted horizontal mattress suture was placed in each commissure and each sinus of Valsalva at the level of the sinotubular junction. The heart and thoracic aorta were fixed on a table and the interrupted sutures were drawn horizontally. As a result, the aorta of the junction level was dilated. Strain of the interrupted sutures were changed by weights of 20, 25, 50, 70 and 100 points (1 point = 3.5 g). The sites of the retracted sutures were the three commissures and three sinuses of Valsalva. With increased strain of the sutures, the opening of the aortic valve was exaggerated when drawing was done on either all sutures or the commissures. When drawing was done only on the three sinuses of Valsalva, coaptation of the aortic valve was uninterrupted. This study showed that dilatation of the sinotubular junction causes aortic regurgitation, which is mainly due to the outward deviation of the commissures.

Animals↗
PubMed1998

[Clinical evaluation of Azasetron Hydrochloride: a new selective 5-HT3 receptor antagonist--antiemetic profile and plasma concentration in transcatheter arterial chemoembolization using CDDP for unresectable hepatocellular carcinoma].

We performed a clinical evaluation on the antiemetic profile and the plasma concentration of Azasetron Hydrochloride (a new selective 5-HT3 receptor antagonist), in transcatheter arterial chemoembolization using CDDP for unresectable hepatocellular carcinoma. Antiemetic effects were examined in 32 patients in the serotone group (administration of serotone 10 mg + methylprednisolone 125 mg) and in 77 patients of the control group (administration of metoclopramide 20-30 mg + methylprednisolone 500 mg). The response rate and the CR ratio in serotone group was 97% and 66%, respectively. These results were statistically higher than in the control group. Although all patients had chronic liver diseases, no side effects and complications related to administration of serotone were observed. The average area under the concentration (AUC) curve of plasma serotone in five patients with liver cirrhosis was 531 ng.h/ml, which was greater than that of a healthy volunteer. In conclusion, serotone is a new, safe and useful antiemetic drug in TACE therapy for hepatocellular carcinoma.

Aged↗
PubMed1998

[Influence of acute aortic dissection on long-term results of aortic root reconstruction in patients with Marfan's syndrome].

Objective of this study is to evaluate influence of acute aortic dissection on long-term results of aortic root reconstruction in patients with Marfan's syndrome. 19 patients who underwent consecutive aortic root reconstruction between 1985 May to 1998 February were retrospectively reviewed. Patients who associated acute aortic dissection at the time of operation (group D, n = 7) were compared long-term results with those who did not (group non-D, n = 12). Mean follow-up period was 5.1 +/- 3.2 years and longest follow-up term was 12.5 years. In each group early postoperative death was found in one patient. In-hospital mortality in each group were respectively; 14.2% and 8.3%. Late deaths were found in four patients who all belonged to group D, respectively caused by; rupture of thoracoabdominal aneurysm, DIC after subsequent thoracoabdominal surgery, sepsis due to prosthetic valve endocarditis, and sudden death. Actuarial overall survival rate including operative death in D and non-D group were respectively; 0.0 +/- 0% at 6.6 years and 91.1 +/- 8.0% at 12 years. Overall cumulative survival rate was 56.6 +/- 14.0%. Freedom from cardiovascular events, in D and non-D group were respectively; 0.0 +/- 0% at 6.6 years and 60.0 +/- 25.3%, and freedom free form dilatation of residual aorta were respectively; 0.0 +/- 0% at 6.6 years and 100.0 +/- 0% at 12 years. Freedom from subsequent cardiovascular surgery in group D, group non-D and over-all patients were respectively; 0.0 +/- 0% at 6.6 years, 60.0 +/- 25.3% at 12 years and 42.6 +/- 20.2%. In this study, acute aortic dissection in Marfan's syndrome significantly increased late cardiovascular events including dilatation of residual aorta, subsequent aortic surgery and late mortality. On the other hand, excellent long-term results after aortic root reconstruction were found in non-dissection Marfan's syndrome. Considering high incidence of late dilatation of residual aorta, simultaneous total arch replacement with aortic root reconstruction is recommended in acute dissecting Marfan's syndrome. Whereas, preventive simultaneous arch replacement is not required in non-dissecting Marfan's syndrome because of less postoperative vascular events.

Acute Disease↗
PubMed1998

[A case report of aortic regurgitation associated with rheumatic arthritis].

We report a rare case of aortic regurgitation (AR) associated with rheumatic arthritis (RA). A 61-year-old female was admitted to our hospital with severe heart failure due to AR. She had a 8-year history of RA and had been treated with steroid therapy. Trans-esophageal echocardiography showed thickness and shortening of non coronary cusp (NCC) of aortic valve. After treated for heart failure, aortic valve replacement with SJM-HP 17 mm was done. At operation, right and left coronary cusps were almost normal, but NCC was thickened and shortened. The valve of NCC histology showed granuloma. She recovered uneventfully. Two cases of cardiac valvular disease, associated with granuloma of RA, were reported in Japan. We discussed these cases in this paper.

Aortic Valve↗
PubMed1998

[Application of heparin-coated PCPS for traumatic cardiac rupture: report of a case].

Application of heparin-coated percutaneous cardio-pulmonary support system (PCPS) for a case with traumatic cardiac rupture is reported. A 50-year-old woman, who was injured in the traffic accident, was admitted to our hospital. Her consciousness was not alert in circulatory collapse. Echocardiography showed cardiac tamponade and pericardial centesis was done followed by re-filling. Urgent surgical intervention was necessary. When she was brought to operating room, she became cardiac arrest, necessitating cardio-pulmonary resuscitation followed by PCPS. Under PCPS support, hemodynamic state became stable and cardiac laceration was repaired. Laparotomy was also done because of the distension of abdomen during operation, and splenectomy was necessary for the injured spleen. She is doing well now. Generally, it is considered to be contra-indicated to apply PCPS for traumatic cases which may cause bleeding tendency because of anti-coagulant therapy. But this case report showed the possibility of application of PCPS for traumatic cases, if PCPS is established using heparin-coated system.

Accidents, Traffic↗
PubMed1998

[Usefulness of percutaneous cardiopulmonary bypass support in patients with difficulties in weaning from cardiopulmonary bypass].

A percutaneous cardiopulmonary support system (PCPS) was used in 12 patients (mean age 68 years) between March 1991 and June 1996 for difficulties weaning from ordinary cardiopulmonary bypass. Cardiac procedures preceding the placement of the PCPS were coronary artery bypass grafting in 8 patients, aortic valve replacement in 1, double valve replacement in 1, and ascending aortic replacement for acute aortic dissection in 1. These procedures were elective in 6 patients and emergent in 6. Intraaortic balloon pumps were used in all cases except in two cases with atherosclerotic occlusive disease. Nine (75%) of the patients were weaned from PCPS, and seven (58%) were discharged. There were no complications due to the placement of PCPS except for three episodes of lower leg ischemia. We conclude that PCPS is useful in addressing difficulties in weaning from ordinary cardiopulmonary bypass and there should be further discussion about the limitations of PCPS in cases of severe circulatory failure.

Aged↗
PubMed1997

Computer-Aided Diagnosis of Breast Cancer on Mammograms.

Computer-aided diagnosis (CAD) is a diagnosis made by a physician who takes into account the computer output of quantitative analysis of mammograms. CAD schemes in mammography have been developed to detect lesions such as clustered microcalcifications and masses, and also to distinguish between benign and malignant lesions. Computerized schemes are composed of three major steps which are image processing, quantitation of image features, and data classification. The current performance level of detecting clustered microcalcifications by computer is approximately 85% at a false positive rate of 0.5 per mammogram, whereas the detection accuracy of masses is approximately 90% at a false positive rate of 2 per mammogram. Observer performance studies indicated that computer output can improve the performance of radiologists in detecting clustered microcalcifications by increasing the dtection accuracy to 90% from 80% at a specificity of 90%. The automated classification of clustered microcalcifications is based on quantitative analysis of image features of individual microcalcifications and cluster, followed by artificial neural networks (ANNs) for data classification. With our database, the computer scheme correctly identified 82% of patients with benign lesions, all of whom had biopsies (ie, the radiologist thought the microcalcifications were suspicious for malignancy), and 100% of patients with malignant lesions. On the same set of images, the average of five radiologists was only 27% correct in classifying lesions as benign at 100% sensitivity. The automated classification of masses is made by the quantitation of image features of masses together with a rule-based and ANNs method for data classification. The computer scheme achieved, at 100% sensitivity, a positive predictive value of 83%, which was 12% higher than that of the experienced mammographer and 21% higher than that of the average of less experienced mammographers. The first prototype intelligent workstation for mammography was developed at the University of Chicago, and applied to approximately 12000 screening cases for the detection of early breast cancers. Promising initial results were obtained with the workstation.

Journal Article↗
PubMed1997

Significance of porosity and compliance of microporous, polyurethane-based microarterial vessel on neoarterial wall regeneration.

The microporous structure of artificial vascular grafts, which increases compliance and porosity simultaneously, may enhance neoarterial regeneration. In order to differentiate these effects, three models of segmented polyurethane grafts (inner diameter, 1.5 mm; wall thickness, 100 microns) with or without micropores fabricated using an excimer laser ablation technique, were prepared, and their neoarterial regenerative potentials were studied upon implantation: Model I (microporous, permeable, compliant); Model II (smooth-surfaced, impermeable, compliant); and Model III (smooth-surfaced, impermeable, noncompliant). In Models I and II, the pore or groove size (diameter, 100 microns) and pore or groove arrangement were fixed, and consequently their compliances were almost identical. Irrespective of model, the luminal surfaces were coated with benzophenone-derivatized gelatin and subsequently photocured. Twenty grafts (length, 20 mm) of each model were implanted in the aortas of rats. Predetermined implantation periods were 4, 12, and 24 weeks. Total patency rate decreased in the order Model I (100%), II (87%), and III (59%) grafts. All patent grafts were completely endothelialized after 12 weeks of implantation, irrespective of model. After 12- and 24-week implantations, in Model I grafts, the neoarterial wall was thin, and smooth muscle cells (SMCs) were of the contractile phenotype. In Model II grafts, the neoarterial wall exhibited considerable thickening. In Model III grafts, the neoarterial wall exhibited marked thickening, and SMCs were of the synthetic phenotype. The neoarterial wall thickness at the midportion of the grafts after 24 weeks of implantation increased in the order Model I (48 +/- 8 microns), II (146 +/- 87 microns), and III (385 +/- 21 microns) grafts. These results strongly suggest that compliance matching and porosity synergistically resulted in neoarterial wall restoration without appreciable thickening.

Animals↗
PubMed1997

Cloning of rat uncoupling protein-3 and uncoupling protein-2 cDNAs: their gene expression in rats fed high-fat diet.

In order to elucidate energy balance in the skeletal muscle, we cloned cDNA of a homologue of uncoupling protein (UCP) from rat skeletal muscle. We also cloned rat UCP-2 cDNA from rat brown adipose tissue (BAT). The UCP cloned from rat skeletal muscle showed 57% and 72% identity with rat UCP-1 and UCP-2. The mRNA was expressed abundantly in the skeletal muscle, moderately in the BAT, and slightly in the white adipose tissue (WAT) with a major band at 2.5 kb and a minor band at 2.8 kb, while the UCP-2 gene expression was widely detected in the whole body with substantial levels in the WAT and with slight levels in the skeletal muscle and BAT. The rat UCP cloned in the present study showed 86% identity with the recently cloned human UCP-3, which was also expressed abundantly in the skeletal muscle with a signal of 2.4 kb. Therefore, the rat UCP was considered to be rat UCP-3. In rats fed high-fat diet the UCP-3 gene expression was augmented 2-fold in the skeletal muscle while UCP-2 mRNA levels were increased significantly (1.6-fold) in the epididymal WAT. Augmented expression of UCPs may provide defense against high-fat induced obesity and impairment of glucose metabolism.

Adipose Tissue↗
PubMed1997

Adenovirus-mediated gene transfer of C-type natriuretic peptide causes G1 growth inhibition of cultured vascular smooth muscle cells.

We have proposed the "vascular natriuretic peptide system", in which C-type natriuretic peptide (CNP), the third member of the natriuretic peptide family, can control vascular tone and growth as an endothelium-derived relaxing peptide. We aimed at overexpression of CNP gene in vascular smooth muscle cells (SMCs) by adenovirus-mediated gene transfer to examine the growth characteristics of SMCs via the augmentation of cGMP production. Rat aortic SMCs infected with Ad.CNP, a replication-deficient adenovirus driving rat CNP cDNA, produced 162 +/- 55 fmol/mL of CNP, which was 4,000 times higher than that produced by endothelial cells. cGMP production was also augmented in Ad.CNP-infected SMCs (2200 +/- 270 fmol/10(4) cells). Accordingly, significant growth inhibition was observed in SMCs infected with Ad.CNP. The flow cytometry analysis revealed that the population of the S and G2 + M phases was reduced by 60% of the control in Ad.CNP-infected SMCs. The gene expression of ANP-B receptor, which is expressed abundantly in SMCs with the synthetic phenotype, was suppressed in Ad.CNP-infected SMCs, while the gene expression of ANP-A receptor, which is expressed predominantly in SMCs with the contractile phenotype, became detectable in Ad.CNP-infected SMCs. In addition, the gene expression of smooth muscle myosin heavy chain-2 (SM-2), which is the molecular marker of highly-differentiated SMCs, was also induced in Ad.CNP-treated SMCs. These results suggest that cGMP cascade activation induces re-differentiation of SMCs. The present study demonstrated that overexpression of CNP induced growth inhibition of SMCs at the G1 phase with possible alteration of the phenotype.

Adenoviridae↗
PubMed1997

Cloning and sequencing of the hup gene encoding the histone-like protein HSl of Streptomyces lividans.

The hup gene encoding the histone-like HU-type protein HSl of Streptomyces lividans TK24 was cloned and sequenced. The deduced N-terminal amino acid sequence, molecular mass (9851 Da) and pI (9.95) are in good agreement with characteristics of the HSI protein. The hup transcript of about 500 nucleotides was detected. The 2.3-kb HincII fragment containing the hup gene hybridized with the AseI fragment C in the 9-10 o'clock region of the chromosome of S. lividans ZX7.

Amino Acid Sequence↗
PubMed1997

An ATP-dependent inwardly rectifying potassium channel, KAB-2 (Kir4. 1), in cochlear stria vascularis of inner ear: its specific subcellular localization and correlation with the formation of endocochlear potential.

Cochlear endolymph has a highly positive potential of approximately +80 mV. This so-called endocochlear potential (EP) is essential for hearing. Although pivotal roles of K+ channels in the formation of EP have been suggested, the types and distribution of K+ channels in cochlea have not been characterized. Because EP was depressed by vascular perfusion of Ba2+, an inhibitor of inwardly rectifying K+ (Kir) channels, but not by either 4-aminopyridine or tetraethylammonium, we examined the expression of Kir channel subunits in cochlear stria vascularis, the tissue that is supposed to play the central role in the generation of positive EP. Of 11 members of the Kir channel family examined with reverse transcription-PCR, we could detect only expression of KAB-2 (Kir4.1) mRNA in stria vascularis. KAB-2 immunoreactivity was specifically localized at the basolateral membrane of marginal cells but not in either basal or intermediate cells. Developmental expression of KAB-2 in marginal cells paralleled formation of EP. Furthermore, deaf mutant mice (viable dominant spotting; WV/WV) expressed no KAB-2 in their marginal cells. These results suggest that KAB-2 in marginal cells may be critically involved in the generation of positive EP.

4-Aminopyridine↗