Biomedical subjects

S Yamada

Publications and source records attributed to S Yamada.

At least 631 records · Page 35Linked to original sources

PubMed1997

[45Ca kinetics and calcium balance studies. A useful method for analyzing calcium movement as a whole throughout the entire body in rats].

45Ca kinetics and calcium balance studies allow for the simultaneous determination of calcium movement in the intestines, kidneys and bones. Since the flow of minerals in each of these organs depends on those in other organs, it is important to evaluate calcium movement as a whole throughout the entire body. Morphological methods can be used to evaluate local bone formation and resorption microscopically within defined windows. However, bone remodeling does not proceed equally in every part of the skeleton, and local events tend to be misread as general phenomena. Although variables such as bone formation and resorption obtained in 45Ca kinetics and calcium balance studies tell nothing about the location of these events, and the concept of compartments can be somewhat difficult to understand, this method is still useful for obtaining quite reliable results compared to those obtained by other methods. Our review describes the concept of the compartment model and explains the pertinent methods in comparison with other methods.

Animals↗

PubMed1997

The results of transsphenoidal surgery for 44 consecutive acromegalic patients.

A series of 44 patients with acromegaly underwent transsphenoidal surgery between 1987 and 1996. The early postoperative mean basal GH level < 5 ng/ml or < 3 ng/ml was achieved in 43 (97.7%) or 38 (86.4%) out of 44 patients, respectively. Preoperative abnormal GH secretory response to TRH, GnRH and oral glucose administration was restored to normal both after surgery and at the time of the final follow-up in all patients whose early postoperative mean basal GH levels were reduced to < 3 ng/ ml, whereas they remained abnormal in those with mean basal GH levels of > or = 3 ng/ml. In contrast, insulin-like growth factor 1 (IGF-1) levels, when measured by the extraction method, tended to be reduced gradually to normal between 6 months and 2 years after surgery in some patients with a successful operation. Therefore, 34 (87.1%) out of 39 patients who have been followed up longer than 6 months met the following stringent criteria at the time of the final follow-up: mean basal GH level < 3 ng/ml, a normal IGF-1 level, and normal GH response to TRH, GnRH and oral glucose administration. In this series, the most unfavorable preoperative factor influencing operative outcome is tumor invasion of the cavernous sinus. Our results clearly indicate that selective adenomectomy by transsphenoidal surgery is the therapy of first choice in any patient with acromegaly and that the complete biochemical cure of acromegaly can be achieved in 87% of patients by surgery alone with an acceptable low surgical morbidity.

Acromegaly↗

PubMed1997

Infrequent mutations of p16INK4A and p15INK4B genes in human pituitary adenomas.

The p16INK4A and p15INK4B genes on chromosome 9p21 encode the p16 and p15 inhibitors of cyclin D/cyclin-dependent kinase 4 complexes respectively. Mutations and deletions of the p16INK4A gene have been found in melanomas and many other types of tumors. To assess the role of the p16INK4A and p15NK4B genes in tumorigenesis of the pituitary gland, 31 sporadic pituitary adenomas and 2 pituitary adenomas in familial acrogigantism were examined for loss of heterozygosity on 9p21-22 and screened for mutations in the p161NK4A and p15INK4B genes. To identify pituitary adenomas which had lost 9p21-22, pituitary adenomas were genotyped with markers flanking the p16INK4A and p15INK4B loci. The frequency of mutations in coding regions of the p16INK4A and the p15INK4B genes in pituitary adenomas was determined with polymerase chain reaction-single strand conformation polymorphism analysis and sequencing of variants. Of the 33 pituitary adenomas, two revealed loss of 9p21-22 sequences, but none of them had tumor-specific mutations. We conclude that mutations of the p16INK4A and p15INK4B genes are not required for tumorigenesis of the pituitary gland.

Adenoma↗

PubMed1997

Superovulation induction in the house musk shrew (Suncus murinus).

The number of ovulated oocytes in the adult house musk shrews was examined by natural mating. The positive rate of ovulation was 83.3%, and the mean number of ovulated oocytes was 4.4 +/- 1.9 (Mean +/- SD). The induction of superovulation was examined by administering either pregnant mare's serum gonadotropin (PMSG) or human chorionic gonadotropin (hCG), exogenous gonadotropin, to house musk shrews. As a result, the number of ovulated oocytes were within the number of oocytes ovulated spontaneously. The method of superovulation induction by administering both PMSG and hCG to house musk shrews was investigated. In the group intraperitoneally with 7.5 i.u. of PMSG followed by 7.5 i.u. of hCG 48 hr later, the positive rate of ovulation was as high as 94.6% and the mean number of ovulated oocytes was 11.7 +/- 13.4. Moreover, in 15 out of these 35 animals positive for ovulation, 10 oocytes or more were observed and the mean number of ovulated oocytes was 21.0 +/- 16.5, showing the superovulatory response. In the group of 5.0 i.u. PMSG and 5.0 i.u. hCG injected at an interval of 72 hr, every animal was induced to ovulate and the mean number of ovulated oocytes was 41.3 +/- 19.9. Thus, the injection of PMSG and hCG at a longer interval increased the number of superovulated oocytes. Furthermore, 97.5% of eggs recovered from superovulating animals contained cumulus cells.

Animals↗

PubMed1997

An analysis of users' preference on keyboards through ergonomic comparison among four keyboards.

The usability of four kinds of keyboards as regards touch and feel was evaluated by measuring the performance and eliciting the preferences of a total of 24 Japanese participants in a test that consisted of typing English text. It was found that quiet keyboards with an indistinct tactile feedback tend to give higher uncorrected error rates than keyboards with a distinct tactile feedback and clicking sound, while no significant difference in throughput was found among the four keyboards. As regards preference, the test participants were divided into two groups: those who preferred keyboards with a distinct tactile feedback and clicking sound, and those who preferred keyboards with an indistinct tactile feedback and no sound. Analysis revealed that these two groups also showed different sensations and preferences with respect to several aspects of the touch and feel of keyboards. This result suggests that suppliers of computer keyboards should provide two kinds of keyboards, with distinct and indistinct tactile key switches, in order to satisfy as many users as possible.

Computer Peripherals↗

PubMed1997

Mutations in the hepatocyte nuclear factor-1alpha gene (MODY3) are not a major cause of late-onset NIDDM in Japanese subjects.

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Age Factors↗

PubMed1997

Identification of mutations in the hepatocyte nuclear factor (HNF)-1 alpha gene in Japanese subjects with IDDM.

One form of maturity-onset diabetes of the young, MODY3, is characterized by a severe insulin secretory defect, compared with MODY2, a glucokinase-deficient diabetes. It has recently been shown that mutations of the gene encoding the transcription factor hepatocyte nuclear factor (HNF)-1 alpha cause MODY3. Because of the rapid progress to overt diabetes and the high prevalence of required insulin treatment in patients with MODY3, we screened the HNF-1 alpha gene for mutations in Japanese subjects with IDDM. Ten exons and flanking introns of the HNF-1 alpha gene in these subjects were amplified by polymerase chain reaction and direct sequencing of the products. Mutations were identified in three (5.5%) of the 55 unrelated subjects with IDDM. A missense mutation of R272H (replacement of Arg by His in codon 272) in the DNA binding domain of HNF-1 alpha was found in a subject who developed IDDM 1 year after diagnosis of NIDDM at 8 years of age. A frameshift mutation of P291 fsinsC (insertion of a C in a polyC tract around codon 291 for Pro), which would generate a mutant truncated protein of 340 amino acids, was found in a subject who started insulin treatment when hyperglycemia and ketonuria were noticed at 13 years of age. A missense mutation of R583G (replacement of Arg by Gly in codon 583) in the transactivation domain of HNF-1 alpha was found in a subject with sudden-onset IDDM at 20 years of age. None of these mutations were present in 100 nondiabetic subjects (200 normal chromosomes). These results indicate that the HNF-1 alpha gene defects could lead to the development of not only early-onset NIDDM but also IDDM, implicating the importance of subclassification of HNF-1 alpha-deficient IDDM from a classical type of autoimmune-based IDDM in Japanese.

Adolescent↗

PubMed1997

Quantitative evaluation of brain distribution and blood-brain barrier efflux transport of probenecid in rats by microdialysis: possible involvement of the monocarboxylic acid transport system.

This study was performed to evaluate quantitatively the brain distribution and the efflux transport across the blood-brain barrier of probenecid, using in vivo microdialysis and in situ brain perfusion techniques. The brain interstitial fluid (ISF)-to-plasma cerebrospinal fluid (CSF)-to-plasma and brain tissue-to-plasma unbound concentration ratios of probenecid at steady state were less than unity, which suggests restricted distribution in the brain. An uphill concentration gradient from ISF to plasma and a downhill concentration gradient from CSF to ISF were observed. Kinetic analysis revealed that the efflux clearance from brain ISF to plasma (0.0373 ml/min/g brain) was significantly greater than the influx clearance from plasma to brain (0.00733 ml/min/g brain). The ratio of the ISF concentration (Cisf) to the plasma unbound concentration (Cp,f) of probenecid was increased 2- to 3-fold by salicylate (3.7 mM) and benzoate (3.6 mM), which are accepted as substrates of the monocarboxylic acid transport system, compared with the same ratio for the control. In addition, the ratio Cisf/Cp,f was increased by treatment with N-ethylmaleimide, a sulfhydryl-modifying agent, whereas p-aminohippuric acid and choline did not produce increasing effects on Cisf/Cp,f. These data suggest that the restricted distribution of probenecid in the brain may be ascribed to efficient efflux from the brain ISF, which may be regulated by the monocarboxylic acid transport system at a relatively high ISF concentration.

Animals↗

PubMed1997

Assessment of cancer recurrence in residual tumors after fractionated radiotherapy: a comparison of fluorodeoxyglucose, L-methionine and thymidine.

UNLABELLED: This study evaluates the midterm follow-up of tumor and normal tissue uptake of deoxyglucose, thymidine and methionine after fractionated radiotherapy to assess cancer recurrence in residual tumors. METHODS: AH109A tumor-burdened rats were treated with one to eight doses of 5Gy 60Co radiation. Tissue distribution study with 18F-FDG, 3H-thymidine and 14C-methionine, double-tracer autoradiography with 18F-FDG and 14C-methionine, and single-tracer autoradiography with 14C-labeled deoxyglucose, thymidine and methionine were performed 6 days after the end of therapy. RESULTS: Dose response study shows a significant decrease of tumor uptake of all tracers after two and more doses, even in the case of later recurrence. Whereas 3H-Thd and 14C-Met tumor uptake was similar to that of normal muscle, 18F-FDG tumor uptake remains higher than that of muscle, even in the case of complete tumor cure. The irradiated muscle shows a higher 18F-FDG uptake than the nonirradiated muscle. Autoradiography after eight doses (100% tumor cure) reveals elevated 14C-DG tumor uptake to be ascribable to nonmalignant cellular elements, in particular to a macrophage layer at the rim of necrotic areas. Autoradiography after four and six doses (33% and 57% tumor cure) shows the highest methionine and thymidine uptake in viable cancer cells, whereas deoxyglucose uptake did not differ between viable cancer cells and macrophages. CONCLUSION: To detect and differentiate viable cancer cells in a residual tumor mass after radiotherapy, PET using 11C-methionine or 11C-thymidine may have some advantages over 18F-FDG, especially if the residual tumor includes larger areas of necrosis.

Animals↗

PubMed1997

[Serological diagnosis of enterohaemorrhagic Escherichia coli(EHEC) infection by passive hemagglutination assay].

The passive hemagglutination(PHA) assay was developed to diagnose enterohaemorrhagic Escherichia coli(EHEC) infections serologically and was evaluated for the utility. The PHA assay was done using formalinized sheep erythrocytes sensitized with 2 kinds of antigens; soluble native and heat-treated antigens, by a microtiter method. A total of 63 serum samples from 33 HUS patients and 30 sporadic hemorrhagic colitis were subjected to the assay. For the control, 30 serum samples from 20 healthy adults and 10 healthy children were used. Thirty-two of 33 HUS patients had the antibody against soluble native antigen and/or heat-treated antigen of EHEC O157. These response was also observed in 14 HC cases with stool culture positive for EHEC O157. Good antibody response was observed against soluble native antigen than that against heat-treated antigen. The PHA titers distributed between 1:100 and 1:8,100 were observed in the samples taken in about 1 week or more after the onset of diarrhea, and the higher titer were observed in HUS patients than in HC patients. All of control sera were negative. The PHA assay described here is highly sensitive, simple and rapid method, and is recommended for the serological diagnosis of EHEC infections.

Adult↗

PubMed1997

[A case of supramediastinal neurinoma: its operative approach (via supraclavicular route) and radiographic findings (target sign)].

A 76-year-old female with supramediastinal tumor was admitted. CT scan showed central high density area surrounded by low density area and MR imaging emphasized the same concentric circle. This concentric circle pattern on CT scan and MR imaging is called "Target sign", which is known as characteristic radiographic finding of neurinoma. Therefore we could diagnose her case as mediastinal neurinoma preoperatively. She underwent operation through the supraclavicular approach and the tumor was completely resected. By incising the skin through the modified left hemi-collar incisional line and cutting the clavicula at its central part, we could ensure a good operative field and safely performed this operation without mid-sternotomy or thoracotomy. The supraclavicular approach for the operation of supramediastinal tumor is useful.

Aged↗

PubMed1997

Serum transforming growth factor-alpha level can be a parameter for evaluating liver regeneration after partial hepatectomy in patients with liver cancer.

Sensitive and reliable laboratory parameters are necessary to evaluate the degree of liver regeneration serially in patients after partial hepatectomy for liver cancer. We evaluated the serum levels of transforming growth factor-alpha (TGF-alpha) and hepatocyte growth factor (HGF), both of which are potent mitogens for hepatocytes, in 22 hepatectomized patients with liver cancer: 10 patients with hepatocellular carcinoma and 12 patients with metastatic liver tumors. Ten patients who underwent laparotomy for nonhepatic surgery were also studied as surgical controls. The serum TGF-alpha and HGF levels were measured by sandwich enzyme-linked immunosorbent assay techniques. Both the serum TGF-alpha and HGF levels increased after partial hepatectomy. However, there was no correlation between the levels of TGF-alpha and HGF. The maximal level of TGF-alpha achieved in each case correlated significantly with the resected liver volume and the increased volume of the remaining liver. Hepatocyte growth factor showed no such correlations. After nonhepatic surgery, the HGF level also increased significantly, while the TGF-alpha level did not. These results suggest that the serum TGF-alpha level varies depending on the regenerative stimulus to the liver, and that its increase corresponds with the degree of liver regeneration that occurs in patients after partial hepatectomy for liver cancer. In contrast, it is unlikely that the serum HGF level reflects liver regeneration. In conclusion, the serum TGF-alpha level can be used as a parameter for evaluating liver regeneration in patients who have undergone partial hepatectomy.

Carcinoma, Hepatocellular↗

PubMed1997

[Radiation therapy for low-grade astrocytomas: survival and QOL].

From 1980 to 1994, 59 patients with a diagnosis of lowgrade astrocytoma were treated in our hospital. We analyzed survival, prognostic factors and quality of life (QOL) in survivors who had been recurrence free for at least 2 years. The overall 2-, 5- and 10-year survival rates were 75, 65 and 49 % respectively. The major prognostic factors were field size (the smaller, the better) and age (the younger, the better) according to Cox regression analysis. Quality of life was evaluated in the 20 patients who had survived at least 2 years without tumor regrowth. Performance status was good in most of the patients, and 17(85%) patients were intellectually and physically normal. Headache, fatigue and memory difficulties were the major clinical complaints of these patients and were observed in 7(35%), 6(30%) and 7(35%) of the patients, respectively, although severe symptoms were rare.

Adolescent↗

PubMed1997

HTLV-I pX transgenic rats: development of cytokine-producing mammary carcinomas and establishment of the pX mammary carcinoma cell lines.

In two lines of transgenic rats (pX rats) from WKAH and F344 strains and carrying the HTLV-I pX gene under control of the mouse H-2Kd promoter, mammary carcinomas developed predominantly in females starting at about 5 months of age. The incidence of the tumor reached about 40% when the rats were 12 months old. Histology of the tumor was undifferentiated carcinoma with massive infiltration of granulocytes into the tumor tissue. Systemic granulocytosis and hepato-splenomegaly due to extramedullary granulocytopoiesis were seen in pX rats and nude mice bearing pX mammary tumor. mRNAs of both pX and host genes, Gro and MIP-2, which are granulocyte chemoattractants of the IL-8 family, were highly expressed in the tumor tissue. Since expression and point mutation of several oncogenes and anti-oncogene, related with mammary carcinomas, were not demonstrated, hitherto unidentified novel oncogenic pathways may be transactivated by the pX transgene in these pX rats. pX mammary carcinoma cell lines, which have similar characteristics to the primary tumor, were established and the cells underwent apoptosis under the serum deprived conditions. The pX rats and the pX mammary carcinomas appear to be suitable models for analyses of HTLV-I pX oncogenesis and immune pathogenesis in vivo and in vitro.

Animals↗

PubMed1997

[Intraoperative and follow-up color Doppler echocardiography for evaluating the surgical results of aortic valvuloplasty in a patient with bicuspid aortic valve].

A 21-year-old man underwent aortic valvuloplasty for aortic regurgitation due to bicuspid aortic valve. After the initial procedure for valvuloplasty of the anterior cusp, transesophageal color Doppler flow imaging revealed a significant regurgitant jet directed posteriorly as observed preoperatively. After an additional valvuloplastic procedure for the anterior cusp, the size of the regurgitant signal was reduced and directed to the center of left ventricular outflow tract. The surgery was then completed. On the 5th postoperative day, an aortic regurgitant murmur reappeared and color Doppler echocardiography showed a mild but significant regurgitant jet directed toward the interventricular septum, which may have been due to contraction of the anterior cusp treated by valvuloplasty. Aggravation of the aortic regurgitation in the early stage after plastic surgery is important and requires consideration in the intraoperative assessment.

Adult↗

PubMed1997

[Cost effectiveness analysis of FDG-PET in the differential diagnosis and staging of lung cancer in Japan].

UNLABELLED: Several studies have shown that FDG-PET is more accurate than CT for the differential diagnosis and for the staging of lung cancer. We have analyzed potential effect of FDG-PET on the medical cost for the management of patients suspected of lung cancer. In the differential diagnosis, chest CT plus FDG-PET protocol reduced the number of bronchofiberscope (BFS) and biopsy by one fourth of that in the conventional protocol using CT alone. PET protocol reduced unnecessary examinations for the patients of benign disease, however, it increased the total cost of examinations by 25% due to the higher cost of PET than that of BFS and biopsy in Japan. In the staging of lung cancer, PET protocol improved accuracy of staging, reduced unnecessary surgery by 67%, and showed a saving of the cost of examination by 5%, and the total medical cost by 2.5% compared to that in the conventional protocol using CT, brain MRI, and bone scan. CONCLUSION: Use of FDG-PET for the staging may contribute to the improvement of patient management of lung cancer patients also to the saving of the medical cost.

Cost-Benefit Analysis↗

PubMed1997

[Successful treatment of toe gangrene with moderate-dose steroid therapy in a patient with systemic sclerosis (CREST syndrome)].

A 68-year-old woman first noticed Raynaud's phenomenon at the age of 35, and she was diagnosed as having systemic sclerosis (SSc) because of cutaneous calcinosis, sclerodactyly, telangiectasia, sausage-like finger, digital pitting scar in 1971. In October, 1994, she was suffered from cold sensation in her right foot, and on November 2 she noticed the painful ulcers on the right toe, which progressed to be gangrenous. Every antiplatelet or thrombolytic agents including PGE1, argatroban, sarpogrelate hydrochloride and urokinase were unsuccessful. Angiograms revealed marked narrowing of bilateral anterior and posterior tibial and peroneal arteries. Prednisolone 30 mg/day was started, which resulted in successful response within 10 days. Large vessel involvement in SSc patients has been reported to be rare, and its treatment remains to be established. We believe our case help understanding the pathophysiology of such rare manifestation in SSc.

Aged↗

PubMed1997

[Cine display of postprocessed 3D MR images of the thoracic aorta].

We have developed a cine display of postprocessed 3D MR images of the thoracic aorta. Maximum intensity projection (MIP) images of the thoracic aorta in each phase were reconstructed from consecutive 2D-cine MR data sets, and displayed in a cine loop. The postprocessed 3D MR images clearly showed the relationship between major cervical branches and aortic pathologies such as aneurysms, and cine display presented the flow pattern in the aorta. 3D-cine MR angiography seems to be useful for follow-up studies of thoracic aortic diseases especially in patients with renal dysfunction.

Adult↗