Biomedical subjects

T Tamada

Publications and source records attributed to T Tamada.

At least 37 records · Page 2Linked to original sources

PubMed1999

Aging and salt-loading modulate blood pressure QTLs in rats.

To evaluate the effects of nongenetic factors, aging, and salt-loading on the quantitative trait loci (QTLs) for blood pressure (BP), we conducted a genome-wide linkage analysis using multiple sets of BP measurements in 125 male F2 generation cross derived from stroke-prone spontaneously hypertensive rats and normotensive Wistar-Kyoto rats. The experiment was arranged in two stages. In the first stage, corresponding to the developing period of the rats, BP was measured repeatedly without loading of salt; this continued until the rats were 5 months of age. In the second stage, after the baseline BP leveled off, 1% salt water was given to the rats and BP was monitored for the subsequent 7 months. Genome scanning was performed using 201 markers. In the developing period, three QTLs were identified on chromosomes 1, 3, and 4 (logarithmic odds [LOD] scores of 5.6, 3.1, and 3.2, respectively), which had peaks at 8 or 10 weeks of age. In the latter salt-loading stage, QTLs for BP were detected on chromosomes 1 and 10 (LOD scores 4.6 and 4.5, respectively). When the BP increase during salt-loading was analyzed as a phenotype, however, only the region on chromosome 10 showed linkage at a suggestive level (LOD score 3.2). The present study provides experimental evidence that QTLs for BP could be modulated by nongenetic factors, such as aging and salt-loading.

Aging↗

PubMed1999

Analysis in spontaneously hypertensive rats.

1. Linkage analysis is performed between basal or salt-sensitive high blood pressure and several loci on chromosomes in F2 progenies obtained from crossing stroke-prone spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats. 2. Basal hypertensive genes are mapped to a region near the D1Mit2 locus on chromosome 1 and near the D3Mgh8 locus on chromosome 3 in the male and female F2 progenies. 3. Salt-sensitive hypertensive gene is mapped to a region near RR1023 locus on chromosome 10 in the male F2 progenies. 4. Salt-sensitive hypertensive gene is mapped to a region near D3Mgh12 locus on chromosome 3 in the female F2 progenies.

Animals↗

PubMed1999

Cholinomimetic action of macrolide antibiotics on airway gland electrolyte secretion.

We investigated the acute effects of erythromycin (EM) and its derivatives on ionic currents in airway glands from feline tracheae. Therapeutic concentrations of EM or clarithromycin (CAM) attenuated the whole cell currents evoked by ACh in a competitive manner. The maximally stimulated inward Cl- currents were reduced to 54 and 83% and the outward K+ currents to 55 and 84% of control values by EM and CAM, respectively, whereas the responses induced by phenylephrine, norepinephrine, caffeine, or ionomycin were unaffected by EM, CAM, or EM523, a synthetic derivative of EM. K+ channels in excised outside-out patches were not influenced by macrolides. Although therapeutic concentrations of macrolides showed no effect on the baseline currents, high concentrations of macrolides alone evoked currents mimicking the ACh response, which were abolished completely by atropine. We concluded that macrolides act as a partial agonist on cholinergic receptors, resulting in a reduction of Cl- secretion at pharmacological doses of the agents, which may exhibit a pronounced effectiveness on hypertrophied and/or cholinergically sensitized submucosal glands in pathological airways.

Acetylcholine↗

PubMed1999

[Chronological study for solitary bone metastasis in the sternum from breast cancer with bone scintigraphy].

Since breast cancer is frequently associated with bone metastasis, bone scintigraphies have been performed to determine pre-operative staging and to survey postoperative bone metastasis. The sternum, in particular, is a site at which is difficult to differentiate between benign bone disease and bone metastasis, because of varied uptake and wide individual variations. In this study, chronological bone images were scintigraphied in six cases with solitary sternal metastasis and three cases with benign bone disease including two fracture cases and one arthritis case. On bone scintigrams in which solitary sternal metastasis appeared, increased uptake was found in five cases, and photon deficiency was observed in one case. During follow-up scintigraphies, abnormal accumulations, such as hot spots and cold lesions, increased in the bone metastasis while abnormal uptake disappeared or was unchanged in the benign bone disease cases. On CT, four cases showed osteolytic change, and one exhibited osteosclerotic change. These findings indicate that sternal metastasis usually shows osteolytic change, even if a hot lesion is recognized on bone scintigraphy. In solitary sternal metastasis, for which early diagnosis is difficult, both an integrated diagnosis using other imaging techniques and chronological bone scintigraphy are important.

Adult↗

PubMed1999

[Usefulness of 67Ga scintigraphy in deciding surgical indication in secondary hyperparathyroidism].

In order to evaluate the usefulness in deciding surgical indication in secondary hyperparathyroidism (SHP), 67Ga scintigraphy was performed in 37 patients of SHP before parathyroidectomy (PTx). The radionuclide accumulation in skull and submandible was classified into 4 patterns (skull-submandibular pattern, skull pattern, submandibular pattern and normal pattern). Serum alkaline phosphatase levels were significantly elevated in patients of skull-submandibular pattern (13 cases) compared with skull pattern (6 cases), submandibular pattern (6 cases) and normal pattern (12 cases). Serum intact parathyroid hormone levels were significantly elevated in patients of skull-submandibular and skull patterns compared with normal pattern. No significant difference was observed among the weight of resected parathyroid glands. In 4 of 6 patients of normal pattern on 67Ga scintigram, bone scintigraphy showed a characteristic pattern of SHP including an increased accumulation in the skull and submandible. Bone mineral density (BMD) in the distal radius was increased within six to twelve months after PTx in 10 of 11 patients of skull-submandibular pattern on 67Ga scintigram, whereas only one patient showed an increase in BMD in 9 patients of normal pattern. In summary, it was concluded that 67Ga scintigraphy could provide a useful information in deciding the indication for PTx in secondary hyperparathyroidism.

Citrates↗

PubMed1999

[Fundamental study of the detection of metastatic bone tumors with whole-body MR imaging].

Preliminary studies were performed to evaluate the usefulness of whole-body magnetic resonance imaging (WB-MRI) in the screening of bone metastases. The fast short TI inversion recovery sequence was the most suitable method because of its minimal image distortion and uniformity of fat suppression in a large field of view. In 4 cases of malignant tumor, the localization of all 8 bone metastases detected with bone scintigraphy (BS) could be clarified with WB-MRI. Furthermore, WB-MRI with fast STIR alone could depict 4 lesions undetected by BS, and WB-MRI combined with contrast enhancement could depict 5 such lesions.

Bone Neoplasms↗

PubMed1998

Vascular movement of beet necrotic yellow vein virus in Beta macrocarpa is probably dependent on an RNA 3 sequence domain rather than a gene product.

RNAs 1 and 2 of beet necrotic yellow vein virus (BNYVV) carry the functions enabling viral RNA replication, cell-to-cell movement, virus assembly and vascular movement of the virus in the systemic host Spinacea oleracea. In Beta macrocarpa, on the other hand, BNYVV RNA 3 is required for vascular movement. Replication-competent RNA 3 transcripts carrying various point mutations and deletions were coinnoculated with RNAs 1 and 2 to young leaves of B. macrocarpa and the ability of the virus to multiply on the inoculated leaves and to invade the plant systemically was examined. None of the RNA 3 mutants tested interfered with virus multiplication in the inoculated leaves. Point mutations designed to specifically block or truncate translation of the ORFs of the two known RNA 3 gene products, P25 and N, did not interfere with vascular movement. Vascular movement was not inhibited by deletions eliminating the short 5'-proximal ORF on RNA 3 (ORF A) or by point mutations blocking putative translation of the short 5'-proximal ORF (ORF S) on RNA 3sub, a subgenomic RNA derived from RNA 3. On the other hand, deletions in a 'core region' encompassing nucleotides 1033-1257 of RNA 3 completely blocked vascular movement of the virus while removal of sequences flanking the core region lowered its efficiency. The observations suggest that some feature of the RNA 3 sequence rather than an RNA-3 coded protein is important for vascular movement of BNYVV in B. macrocarpa.

Chenopodiaceae↗

PubMed1997

MRI in carcinomatous encephalitis.

We report a rare case of miliary brain metastases presenting with symptoms similar to encephalitis ("carcinomatous encephalitis"). Contrast-enhanced MRI demonstrated miliary metastases more distinctly than other imaging methods and reproduced the pathological features.

Adenocarcinoma↗

PubMed1997

Crystal structure of DNA photolyase from Anacystis nidulans.

The crystal structure at 1.8 A resolution of 8-HDF type photolyase from A. nidulans shows a backbone structure similar to that of MTHF type E. coli photolyase but reveals a completely different binding site for the light-harvesting cofactor.

Amino Acid Sequence↗

PubMed1997

Arthritis and meningitis--the first manifestations of bacterial endocarditis in 2 patients.

We have encountered 2 patients in whom the first manifestations of bacterial endocarditis were arthritis (in 1 case septic arthritis and in the other nonseptic arthritis) and bacterial meningitis. These presentations were followed by acute heart failure due to aortic valve destruction, although the patients showed no significant cardiovascular manifestations on admission. Aortic valve replacement was performed in each case and the patients' postoperative course was comfortable. We would like to emphasize the following points. (1) Arthritis and meningitis are uncommon in patients with bacterial endocarditis. However, it is necessary to consider the possibility of bacterial endocarditis when these clinical manifestations present together. Such a combination can cause rapid valve destruction. When more than 2 rare complications of bacterial endocarditis coexist, surgery should be considered as soon as the definite diagnosis of bacterial endocarditis is established, even if congestive heart failure has not yet developed. (2) Arthritis associated with bacterial endocarditis might be truly septic rather than mediated by circulating immune complexes as is commonly believed.

Aged↗

PubMed1997

Hyperamylasemia in response to ritodrine or ephedrine administered to pregnant women.

BACKGROUND: Ritodrine and ephedrine can induce hyperamylasemia in pregnant women. The incidence of these beta-agonist-induced hyperamylasemias and their interaction on serum amylase activity are not known. STUDY DESIGN: Serum amylase activity was determined 12 to 24 hours after the administration of ritodrine alone (n = 140), ephedrine alone (n = 160), ephedrine and ritodrine simultaneously (n = 34), and ephedrine after prolonged (> or = 7 days) use of ritodrine (n = 101). RESULTS: A significantly higher incidence of hyperamylasemia (amylase > 215 IU/L) was seen in a group treated with ritodrine alone (60/140, 43 percent), ephedrine alone (54/160, 34 percent), or ephedrine plus ritodrine (24/34, 71 percent) compared with untreated pregnant women (21/426, 4.9 percent). There was no difference in the incidence of hyperamylasemia among the untreated pregnant women and women who received ephedrine after long-term ritodrine (8/101, 7.9 percent). Isozyme patterns, examined in 72 out of the 146 women with hyperamylasemia after such medications, indicated that salivary-type amylase exclusively was hypersecreted. CONCLUSIONS: Clinical doses of beta-agonists such as ephedrine or ritodrine induce hypersecretion of salivary-type amylase in approximately one-third of women who are pregnant. Desensitization to beta-agonists may occur after prolonged use of ritodrine.

Adolescent↗

PubMed1997

[Small cell lung cancer with acute monocytic leukemia after combined chemotherapy including etoposide].

Small cell lung cancer (stage IIIB) developed in a 61-year-old woman. She was treated with chemotherapy in which the cumulative dose of carboplatin was 662 mg/m2 and that of etoposide was 2,000 mg/ m2, and with concurrent irradiation in which the total dose of X-rays was 44.8 Gy. The response to chemotherapy and irradiation was very good. Radiation pneumonitis developed after discharge, but it resolved after steroid therapy. Nine months after the diagnosis of lung cancer the patient was readmitted because of bleeding and leukocytosis. Acute monocytic leukemia (M5a) was diagnosed after examination of a bone-marrow aspirate. The patient was treated with chemotherapy, but she died of severe bone-marrow suppression and multiple organ failure 3 months after the diagnosis of acute monocytic leukemia. Although chromosome analysis could not be done, we strongly suspect that this leukemia was induced by etoposide, because of the clinical course.

Antineoplastic Agents, Phytogenic↗

PubMed1997

[Comparative study on the tumor accumulation of 99mTc-tetrofosmin and 99mTc-MIBI in rabbits bearing VX-2 cancer].

Each of myocardial blood flow imaging agents has a potential usefulness as an agent for tumor scintigraphy. The tumor accumulation and washout of 99mTc-tetrofosmin and 99mTc-MIBI were comparatively studied using rabbits bearing VX-2 cancer. From seventeen to twenty days after the implantation of VX-2 cancer into the femoral region of seven rabbits, tumor to soft tissue accumulation ratio (T/S ratio) of each agent was calculated in early images (5 min after injection) and in late images (50 min after injection). Compared with 99mTc-tetrofosmin, the T/S ratio of 99mTc-MIBI was higher and, moreover, the washout was delayed. These results suggest that there is a difference in tumor accumulation property between these two agents.

Animals↗

PubMed1996

The region responsible for stroke on chromosome 4 in the stroke-prone spontaneously hypertensive rat.

To detect genetic loci responsible for stroke susceptibility, we produced 107 male F2 progenies crossed between stroke-prone spontaneously hypertensive rats (SHRSP/Izm) and normotensive Wistar Kyoto rats (WKY/Izm) and followed them up until they developed cerebral stroke. One hundred and twenty-five simple sequence repeat (SSR) markers were analyzed in these F2 rats. Nine of 107 F2 rats suffered from macroscopically overt stroke. In these 9 rats, the segregation ratio of 3 genotypes at 6 SSR marker loci on chromosomes 2, 4, 9, and 10 was highly distorted from the expected value (the observed sp/sp:sp/wky:wky/ wky ratio was either 6:3:0 or 6:2:1, while the expected was 1:2:1, p < 0.01 by chi 2 test). Further, the brain weight was significantly heavier (p < 0.001) in the F2 rats suffering from stroke, suggesting that the brain weight was a parameter for stroke. The brain weight of F2 rats cosegregated with D4Mit19, D4Mgh7, and D4Mgh8 (p = 0.0015, 0.0014, and 0.0040 by ANOVA, respectively) on chromosome 4 supporting genetic effects of this genetic loci on the pathogenesis of cerebral stroke. Blood pressure did not cosegregate with these markers on chromosome 4. These results suggest that a region on chromosome 4, independently of hypertension, determines genetic susceptibility to cerebral stroke.

Animals↗

PubMed1996

Complete nucleotide sequence of the Japanese isolate S of beet necrotic yellow vein virus RNA and comparison with European isolates.

The complete nucleotide sequences of beet necrotic yellow vein virus RNA-1 to RNA-4 of the Japanese isolate S (BNYVV-S) were determined and compared with those of French isolate (BNYVV-F2). The nucleotide sequences of the two isolates were very similar, differing by only 1.7% (RNA-1), 4.1% (RNA-2), 2.9% (RNA-3) and 3.6% (RNA-4), respectively. The differences of the amino acid sequences of the two isolates depended upon the open reading frames (ORF) as follows: P237, 1.4%; P22 (coat protein), 2.1%; 54k ORF, 3.4%; P42, 0.5%; P13, 1.7%; P15, 3.0%; P14, 7.0% P25, 6.4%; P31, 3.5%. Comparison of the coat protein and triple gene block (P42, P13 and P15) regions of RNA-2 with other isolates revealed that BNYVV-S was much more similar to the Yugoslavian isolate (BNYVV-Yu2) than to BNYVV-F2. The nucleotide differences between BNYVV-S and BNYVV-Yu2 were less than 1%. Based upon the grouping of BNYVV variants reported by Kruse et al. [10], BNYVV-S is thus considered to belong to the A type along with BNYVV-Yu2, whereas BNYVV-F2 is classified in the B type. Our data suggest that the Japanese isolate S may have been derived from European countries other than France or Germany.

Amino Acid Sequence↗

PubMed1996

The problem of relating fetal outcome with breech presentation to mode of delivery.

We retrospectively analyzed 546 consecutive singleton pregnancies with breech presentations that ended at > or = 36 weeks of gestation for the relationship between the intended mode of delivery and fetal outcome. Twelve patients were excluded from the analysis because these infants had major malformations. Of the 534 remaining patients, 124 (23%) were delivered by elective cesarean section. The other 410 women (77%) went into spontaneous labor. Intrapartum emergency cesarean section was required in 112 (27%) of these 410 women; the other 298 (73%) were delivered vaginally. There were 5 poor neonatal outcomes: 3 perinatal deaths and 2 cases of cerebral palsy probably due to intrapartum asphyxia. The risk of poor outcome was thus 1.2% (5/410), in the intended vaginal delivery group vs. no such outcome in the group of 124 patients that had an elective cesarean section. Three of 5 infants with poor outcome were actually born by emergency cesarean section and comparisons of results according to ultimate method of delivery rather than according to intended method of delivery may be misleading and in our case would have been biased against cesarean section.

Asphyxia Neonatorum↗

PubMed1996

Nucleotide sequence analysis of RNA-5 of five isolates of beet necrotic yellow vein virus and the identity of a deletion mutant.

The nucleotide sequences of RNA-5 from two laboratory isolates (D-5 and D-6) and three field isolates (SH1, S43 and R83) of beet necrotic yellow vein virus (BNYVV) were determined. Isolates D-5 and D-6, derived from a D field culture during mechanical inoculation, contained RNA-5 of molecular size 1.4 kb and 1.0 kb, respectively. The sequences of D-5 SH1, S43 and R83 were found to be at least 98% identical and from 1342 to 1347 nucleotides in length, excluding the poly(A) tail. Each contained a single open reading frame (ORF) encoding a 228 amino acid protein with a molecular mass of 26189 Da (P26). The coding sequence was bordered by a long leader of 443 to 448 nucleotides and a 3'-terminal non-coding region of 215 nucleotides. In isolate D-6, containing the smaller approximately 1.0 kb RNA species referred to as RNA-5a, the ORF had undergone an internal deletion of 303 nucleotides. No sequence identity was found between RNA-5 and either RNA-3 or RNA-4, except for the 5'-terminal nine residues and for approximately the 3'-terminal 200 residues. Thus, the genome organization of BNYVV RNA-5 is very similar to that of RNA-3 and RNA-4, both of which are essential for survival of BNYVV in nature. Although RNA-5 is not essential, it may be associated with symptom expression of BNYVV.

Amino Acid Sequence↗

PubMed1996

High resolution analysis of the readthrough domain of beet necrotic yellow vein virus readthrough protein: a KTER motif is important for efficient transmission of the virus by Polymyxa betae.

The 5'-terminal cistron of beet necrotic yellow vein furovirus RNA 2 encodes the 21 kDa major viral coat protein and terminates with an amber stop codon which can undergo suppression to give rise to a 75 kDa readthrough (RT) protein referred to as P75. P75 is a minor component of virions and the 54 kDa RT domain following the coat protein sequence is important both for virus assembly and transmission by the fungal vector Polymyxa betae. To better define the regions of the RT domain involved in these two steps, RNA 2 transcripts encoding different in-frame RT domain deletion mutants were tested for their ability to form virions when inoculated to plants with the other viral RNAs and to be fungus-transmitted. All deletions in the N-terminal half of the RT domain interfered with virus assembly and partially or completely inhibited fungus transmission. A 4 1 1 nucleotide deletion within the C-terminal half of the RT domain did not inhibit assembly but blocked fungus transmission of the virus. Alanine scanning mutagenesis within the aforesaid 4 1 1 nucleotide subdomain identified a peptide motif (KTER) which is important for the fungus transmission process.

Base Sequence↗