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Biomedical subjects

K Masuda

Publications and source records attributed to K Masuda.

At least 397 records · Page 22Linked to original sources
PubMed1994

[A longitudinal study of CMRGlu in dementia of Alzheimer type].

We studied the serial changes of CMRGlu in 6 patients with dementia of Alzheimer type. All patients demonstrated moderately severe dementia at the initial PET scan. Serial PET scans were performed at an interval of 12 to 24 months. Five of the 6 patients showed a deterioration of clinical symptoms at the second scan. The global CMRGlu serially decreased in all patients. An asymmetry of CMRGlu in both the frontal and parietal regions was observed at the initial PET scan, while the direction of asymmetry was preserved at the second PET scan. The ratios (frontal/parietal and parietal/striatum) of CMRGlu showed no interval change. Therefore, CMRGlu was considered to decrease progressively throughout the entire brain in patients with moderately severe dementia of Alzheimer type.

Alzheimer Disease↗
PubMed1994

[The partial volume effect correction for pulmonary mass lesions using a 68Ga/68Ge transmission scan in PET study].

We tried to correct the partial volume effect for pulmonary mass lesions using a 68Ga/68Ge transmission scan. Initially, a fundamental study was done using spherical phantoms and good results were obtained. Next, a clinical evaluation was performed on 28 pulmonary mass lesions ranging in diameter from 0.8 cm to 8.0 cm. The tissue fractions of the mass lesions were obtained by a 68Ga/68Ge transmission scan, where the tissue fraction in the back muscles was assumed to have a value of 1. The tissue fraction of the surrounding lung field was subtracted from that of each mass lesions, and the net tissue fraction was thereby obtained. When no correction was required, the tumor/muscle count ratio (TMR) became higher in proportion with an increase in the mass size. After performing a correction, however, no correlation was observed between them. This method was both easy to perform and reliable, and it is thus considered to be useful for overcoming the partial volume effect in pulmonary mass lesions, although an underestimation may still occur in cases with mass lesions either near the great vessels or the chest wall.

Gallium Radioisotopes↗
PubMed1994

[A useful method to evaluate 11C-methionine uptake using positron emission tomography: determination of the optimal scanning time for evaluation and a comparison between the tumor-to-muscle ratio and the distribution absorption ratio].

We determined the optimal scanning time for evaluating 11C-methionine uptake and then compared the usefulness of the tumor-to-muscle ratio (TMR) with the distribution absorption ratio (DAR) using positron emission tomography. Forty-two PET studies were performed to examine 42 tumorous lesions, 25 normal lung tissues, 23 normal bone marrow and 39 blood pool. In the 42 lesions examined, the TMR at 5, 10-20, 20-32 and 32-40 minutes after 11C-methionine injection, compared with that at 45-60 minutes, was 96 +/- 23%, 91 +/- 8.6%, 94 +/- 6.9% and 96 +/- 6.9%, respectively. A correlation study between the TMR and the DAR demonstrated good results in both the normal tissue (r = 0.96) and the tumorous lesions (r = 0.93). In conclusion, the 11C-methionine uptake can be evaluated at any time from 10 minutes after the injection of 11C-methionine and both the TMR and the DAR are considered to be useful methods for evaluating 11C-methionine uptake using positron emission tomography.

Absorption↗
PubMed1994

Bacteriological evaluation of a new air turbine handpiece for preventing cross-contamination in dental procedures.

An autoclavable air turbine handpiece, Air Flushing Clean System (AFCS) (Osada Electric Co., Ltd., Tokyo, Japan) was developed for use in dentistry with the objective of reducing cross-contamination. Its potential for bacterial contamination was investigated in vitro using two bacterial strains (Streptococcus mutants ATCC 25175 and Staphylococcus aureus FDA 209 P). In theory, this device should prevent cross-contamination of the internal water and air lines of the handpiece, by maintaining an internal positive pressure even after the turbine is stopped. In the present study, this AFCS device was found to reduce the bacterial contamination within the air turbine handpiece more effectively than the conventional handpiece used according to accepted protocol. The reduction of such contamination by the AFCS is in keeping with the recent objective of the American Dental Association to reduce cross-contamination during dental procedures.

Bacteriological Techniques↗
PubMed1994

Influence of HLA-DRB1 gene variation on the clinical course of Vogt-Koyanagi-Harada disease.

PURPOSE: To investigate the difference, if any, in the immunogenetic backgrounds between two clinical subtypes of Vogt-Koyanagi-Harada disease (VKH). METHODS: HLA-DR4 gene variations were investigated in 46 Japanese patients, 28 with the prolonged type and 18 with the nonprolonged type of VKH. HLA-DR4 genes were amplified with polymerase chain reaction (PCR) and then analyzed for its variation with single-strand conformation polymorphism (SSCP) and restriction fragment length polymorphism (RFLP) methods. RESULTS: Significant differences were found in the DR4 gene variation in the two clinical subtypes. All the patients with the prolonged type had either the DRB1*0405 or DRB1*0410 variant, whereas 39% of the patients with the nonprolonged type had neither of them. This difference in frequency was statistically highly significant (P = 0.00059, Pc = 0.0041). DRB1*0405 was also more frequent in the prolonged type (93%) than in the nonprolonged type (56%) (P = 0.0044, Pc " 0.030). In the prolonged type, relative risk was highest for DRB1*0405/0410 (128), whereas in the nonprolonged type it was highest for DR4 (8.6). CONCLUSION: This preliminary study showed that DR4 gene variants differed significantly between the two subtypes of VKH, suggesting that the clinical course of VKH is determined partly by the patient's HLA-DR gene variation.

Base Sequence↗
PubMed1994

HLA class II genes in Vogt-Koyanagi-Harada disease.

PURPOSE: Vogt-Koyanagi-Harada disease (VKH) is an autoimmune disorder causing a bilateral diffuse granulomatous uveitis, often with several associated extraocular manifestations. Strong association of human leukocyte antigens (HLA) antigens with the disease has been documented. The details of all HLA class II genotypes were investigated in Japanese patients with VKH to demonstrate the immunogenetic background of the disease. METHODS: Human leukocyte antigen tissue typing was performed in 57 Japanese patients with VKH by the modified two-stage complement-dependent microcytotoxicity method. DNA analyses were done by polymerase chain reaction (PCR)-single-strand conformation polymorphism and PCR-restriction fragment-length polymorphism methods. RESULTS: The frequencies of HLA-DR4 and HLA-DQ4 were 93% and 83% among the patients with VKH, compared with 43% and 32% among the controls, respectively (relative risks, 17.4 and 9.9; Pc < 1.0 x 10(-10)). At the genomic level, all patients had the HLA-DQA1*0301 genotype, which was present in only 67% of the normal controls (relative risk, 56.5; Pc < 1.0 x 10(-5)). With allelic combinations, -DQA1*0301/-DR4 showed the greatest relative risk ratio. Conversely, DQB1*0604 genotype was not detected among the patients. CONCLUSION: It can be postulated that VKH is a disease of combined allelic predisposition in which DQA1*0301 acts as the primary and HLA-DR4 acts as an additive factor in the development of the disease. Based on the negative association of DQB1*0604, we propose that DQB1*0604 provides considerable protection, possibly by altering other factors in the pathogenesis of VKH in the Japanese.

Base Sequence↗
PubMed1994

[The development of a new central monitoring system for the operation room].

We developed a practically new central patient monitoring system for the operating room based on a system which had been developed in 1982. Since we introduced this system on May 19, 1992, we have utilized the system in more than 2,000 anesthesia cases. This system has been operating smoothly and accepted well by not only anesthesiologists but also surgeons and nurses. This system is easy to operate, and works automatically, contributing to the early detection of abnormalities in patient's condition. By introducing this system, the anesthesiologists have succeeded in controlling the patient during the operation more elaborately and effectively than before. Automated anesthesia recorder has reduced anesthesiologist's burden of the manual recording.

Anesthesia↗
PubMed1994

[Relation between the clinical course of Vogt-Koyanagi-Harada's disease and human leukocyte antigen (HLA)-DR4 subtypes].

Vogt-Koyanagi-Harada's disease (VKH) is an autoimmune disorder affecting melanocyte-containing tissues. VKH is strongly related to human leukocyte antigen (HLA)-DR4, a heterogeneous HLA specificity consisting of at least 12 different genotypes. The disease has two types: prolonged and non-prolonged, depending upon the clinical course. Fifty-four Japanese patients comprising 27 with the prolonged type, 15 with the non-prolonged type, and 12 new cases of VKH were included in this study. Ninety-three percent of the patients with all types had HLA-DR4. All 27 patients with the prolonged type had either the DRB1*0405 or *0410 genotype, and the non-prolonged type included two DR4-negative and four DRB1*0405 and *0410 negative patients. Our results indicate that the clinical course of VKH is determined partly by the patient's HLA genotype.

Adult↗
PubMed1994

[Pre and post operative evaluation of the perfusion reserve by acetazolamide 99mTc-HMPAO SPECT in patients with chronic occlusive cerebral arteries: a comparative study with PET].

We studied the pre and post-operative perfusion reserve using Diamox 99mTc-HMPAO SPECT in 7 patients with chronic occlusive cerebral arteries and then compared the results with PET. STA-MCA anastomosis was performed on 5 patients, while a carotid endarterectomy was done on 2 patients. The cerebral blood flow, the vascular response to CO2 or Diamox, the oxygen extraction fraction and transit time (CBV/CBF) were measured by PET. In the pre-operative state, the visual evaluations for hypoperfusion area at rest were agreed in 5 out of 7 patients in HMPAO SPECT and PET studies. In the remaining 2 patients, hypoperfusion areas were only detected in the PET study. The pre-operative evaluation of perfusion reserve was agreed in 2 patients. In the remaining 5 patients, 3 patients showed definite positive(++) in PET and positive(+) in HMPAO SPECT, and one patient showed positive (+) in PET and negative (-) in HMPAO SPECT. The post-operative change of hypoperfusion areas was well agreed in HMPAO SPECT and PET studies. However, the change of perfusion reserve was underestimated in HMPAO SPECT compared with PET. In the semiquantitative and quantitative analyses, the count rate ratios (affected/unaffected side) in HMPAO SPECT were apparently higher than those of CBF in PET. The postoperative change of the count rate ratios in HMPAO SPECT were smaller than those of CBF in PET. There was no significant correlation between the change in the ratio of the HMPAO SPECT after the administration of Diamox and the oxygen extraction fraction, and it was thus thought to be impossible to predict the areas with an increased oxygen extraction fraction. Thus, Diamox HMPAO SPECT may underestimate the areas of hypoperfusion or decrease in perfusion reserve when compared with PET. We should consider these limitations in the evaluation of pre and post operative cerebral hemodynamics.

Acetazolamide↗
PubMed1994

[The alpha 1 subunit of voltage-dependent calcium channel expressed in pancreatic beta cells].

Calcium channels play an important role in insulin secretion from pancreatic beta cells, in which two different L-type voltage-dependent Ca2+ channels (VDCC), the beta cell/neuron type and the cardiac type are expressed. The former pre-dominant subtype gene (hCa CN4) consists of 49 exons spanning 120 kilo-bases. The promoter region of hCaCN4 is similar to that of housekeeping gene, which is extremely G+C rich and lacks a TATA-like sequence but has three possible binding regions for transcriptional factor Sp1. Changes of calcium channel mRNA in rat pancreatic islets after glucose infusion are introduced. It is important to investigate variations or mutations in the hCaCN4 gene, causing insufficient insulin secretion, leading to NIDDM.

Amino Acid Sequence↗
PubMed1994

[Linealization correction for acetazolamide (Diamox) 99mTc-HMPAO SPECT image--a comparative study with PET].

We attempted to make a linearization correction for the acetazolamide 99mTc-HMPAO SPECT image. These results were compared to those by PET using the H2(15)O-bolus injection method. The subjects consisted of eleven patients with cerebrovascular diseases. The SPECT images were obtained by the double injection method in the resting state and after an administration of acetazolamide (1 g). Linearization correction was performed according to the Lassen's method. In this study, three different methods were compared, namely fixed Fr and alpha (70 ml/min/100 ml and 1.08), individual determination of Fr and alpha based on PET data, and finally the normalization of the two scan for administered dose, fixed Fr and alpha (50 ml/min/100 ml and 1.5). The corrected count rate ratios of the 99mTc-HMPAO SPECT images were correlated well with the values of regional cerebral blood flow measured by PET in all methods. Therefore, the first method was considered to be a simple and reliable one. In the last method, the relative change of cerebral blood flow after the administration of acetazolamide was calculated. The means of the percentage increase of cerebral blood flow were in good accord between 99mTc-HMPAO SPECT and PET. However, they showed much discrepancy when individually compared.

Acetazolamide↗
PubMed1994

[5-Fluorouracil plus low-dose leucovorin in the treatment of advanced colorectal cancer].

From September 1989 to September 1992, 17 patients (pts) with non-curative or recurrent colorectal cancer were treated with 5-fluorouracil (FU) plus leucovorin (LV) systemic therapy. The sites of evaluable metastases were liver (10), peritoneum (4), lung (3) and others (6). The LV dosage was 30 mg/body (low-dose method) and the FU dosage was 500-750 mg/body. Both drugs were administered either 5 days/every 4 weeks or one day/every 1 to 2 weeks via protracted or bolus infusion. The regimen was generally well tolerated, although 9 pts (53%) experienced toxicity which required dose reductions. Overall response rate was 29% (5 PR). No CR was observed. Improvement in tumor-related symptoms was noted temporarily in 7 out of 10 pts. Serum CEA level decreased in 13 out of 14 pts. All the response sites were liver (5), with simultaneous lung (1) or peritoneum (1) metastasis. The response duration was 3 to 10 months (mean 6.2 months). Second-line therapy after progression of diseases, such as combination with CDDP, was attempted in some of the PR pts, but no re-response was observed. We conclude that FU plus low-dose LV regimen is an effective therapy for advanced colorectal cancer, but further attempts should be made to increase response rate, prolongation of response duration and effective second-line therapy after progression.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1993

[Clinical evaluation of ultrasonic measurement of the calcaneal bone].

We measured the speed of sound (SOS) and broadband ultrasound attenuation (BUA) in the calcaneal bone and compared those values with bone mineral density (BMD) as assessed by single X-ray absorptiometry and dual energy X-ray absorptiometry. Calcaneal speed of sound and broad band ultrasound attenuation showed an earlier decrease with age than lumbar BMD, Calcaneal SOS and BUA correlated well with calcaneal BMD. Calcaneal SOS correlated more closely with neck BMD than lumbar BMD measured by DXA. Furthermore, measurement of calcaneal SOS is more useful than measurement of lumbar BMD to evaluate femoral neck BMD, which might be very important for clinical purposes. Both body weight and height correlated well with calcaneal BMD but not so well with calcaneal SOS or BUA. As ultrasound emits no radiation, we can use it without the restriction of radiation protection.

Absorptiometry, Photon↗
PubMed1993

Behçet's disease associated with one of the HLA-B51 subantigens, HLA-B* 5101.

The strong association of Behçet's disease with HLA-B51 in several ethnic groups is well known. Because the HLA-B51 antigen has been recently identified to comprise three alleles, HLA-B* 5101, HLA-B* 5102, and HLA-B* 5103, we sought to investigate whether there is any correlation of one particular allele among them with B51-positive patients with Behçet's disease. Forty-six Japanese patients with Behçet's disease and HLA-B51 were typed by using the alloantisera, which allowed the subdivision of B51 antigen by the microlymphocyte toxicity assay. All the patients were found to carry HLA-B* 5101. This result suggests that amino acid substitutions at residue 167 or 171 prevent the development of Behçet's disease, because HLA-B* 5101 differs from HLA-B* 5102 and HLA-B* 5103 by single amino acid substitution at residues 171 and 167, respectively, or that another non-HLA gene tightly linked to the HLA-B* 5101-associated haplotype around the HLA class I gene region is responsible for the susceptibility to Bechçet's disease. This study provides insight into the molecular mechanism underlying an HLA association with Behçet's disease.

Alleles↗
PubMed1993

Cloning, functional expression and pharmacological characterization of a fourth (hSSTR4) and a fifth (hSSTR5) human somatostatin receptor subtype.

Somatostatin exerts diverse effects in various tissues upon binding its specific membrane receptors. Recently, we have cloned three different somatostatin receptor subtypes. Here we report the sequence and functional expression of a fourth and a fifth human somatostatin receptor subtype, termed hSSTR4 and hSSTR5, respectively. The hSSTR4 encodes a protein of 388 amino acids and the hSSTR5 is a protein of 364 amino acids. There is 42-60% identity among the amino acid sequences of the five human somatostatin receptor subtypes identified to date. RNA blotting studies reveal that the hSSTR4 is expressed as a single transcript of 4.8 kb in MIA PaCa-2 cells, a cell line derived from human pancreatic cancer while the hSSTR5 is undetectable in the tissues examined. The hSSTR4 and hSSTR5 transiently expressed in COS1 cells exhibit specific binding to somatostatin-14 with IC50 values of 1.6 and 0.16 nM, respectively. We also have characterized the binding affinity of various somatostatin analogues to the hSSTR4 and hSSTR5. The rank of the potency of the analogues are: somatostatin-14 = somatostatin-28 >> RC-160 >> SMS201-995 for the hSSTR4 and somatostatin-28 > somatostatin-14 >> RC-160 > SMS201-995 for the hSSTR5. These results suggest that diverse actions of somatostatin are mediated by at least five somatostatin receptor subtypes with potentially different function.

Amino Acid Sequence↗
PubMed1993

Elevated serum alpha-fetoprotein level of nude mice bearing hepatoma cells by treatment with monoclonal antibodies to alpha-fetoprotein.

This study was carried out to clarify the reason for elevation of serum alpha-fetoprotein (AFP) level of nude mice bearing hepatoma cells after treatment with monoclonal antibodies (MoAbs) to AFP. MoAbs to AFP showed no effect on the cumulative amounts of AFP secreted from human hepatoma cell line, HuH-7, in vitro. However, the treatment of nude mice bearing HuH-7N cells (HuH-7 xenograft) with MoAbs to AFP led to elevation of the serum AFP level in spite of the fact that the growth curve of HuH-7N cells was similar to that for PBS treatment. This apparent elevation of the serum AFP level is thought to be due to the slow elimination of AFP-MoAb immune complexes with little lattice structure from circulation, but not the enhancement of AFP secretion of HuH-7N cells. Thus, when using a MoAb alone or MoAb-drug conjugate, the serum AFP level should only be cautiously used as a tumor marker for evaluating the targeting immunotherapy.

Animals↗
PubMed1993

Identification of three forms of the gamma subunit of G proteins isolated from bovine spleen.

We reported previously that G proteins from bovine spleen contain at least five forms of the gamma subunit (designated S1 through S5), among which S1 and S5 have been identified as novel gamma and gamma 2 subunits, respectively. In this study, we identified the other three forms of the gamma subunit, namely, S2, S3 and S4. Amino acid sequences of proteolytic fragments obtained from S2, S3 and S4 coincided exactly with internal sequences of gamma 7, gamma 5 and gamma 2, respectively. However, sequence analysis of undigested S4 revealed that S4 was an N-terminally truncated form of gamma 2, while analysis of the C-terminal fragment by fast atom bombardment mass spectrometry revealed that the C-terminus of S4 seemed to be geranylgeranylated and carboxymethylated as is that of intact gamma 2. Thus, the three types of gamma subunit obtained from bovine spleen were identified as gamma 7, gamma 5, and an N-terminally truncated gamma 2.

Amino Acid Sequence↗