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Biomedical subjects

W Yamamoto

Publications and source records attributed to W Yamamoto.

At least 37 records · Page 2Linked to original sources
PubMed1999

Sub-super bone scan caused by bone marrow involvement of prostate cancer.

A 67-year-old man presented with malaise and marked anemia. A diagnostic workup revealed severe pancytopenia on a complete blood count and diffuse sclerotic change in the axial skeleton on a plain abdominal radiograph. Bone metastases being suspected from these findings, bone scintigraphy was performed. The bone scan demonstrated uniformly increased skeletal activity with faint soft-tissue activity. The findings of the bone scan, however, appeared atypical of the super scan caused by diffuse bone metastases, without any decrease in radioactivities of the appendicular skeleton and kidneys. Bone marrow scintigraphy with In-111 chloride demonstrated central marrow failure and peripheral expansion, which indicated the possibility of myelophthisis. The patient underwent bone marrow biopsy, which revealed replacement of the bone marrow by metastatic adenocarcinoma. Further examinations detected the primary lesion in the prostate. In this case, the findings of the bone scan were insufficient for the super scan, and might be categorized as a sub-super scan. It would be important to recognize this incomplete form of super scan as a rare scintigraphic pattern of diffuse bone marrow metastases.

Adenocarcinoma↗
PubMed1999

Knowledge, attitudes, beliefs and practices about HIV/AIDS among the overseas job seekers in Bangladesh.

A study of the knowledge, attitudes, beliefs and practices (KABP) relating to HIV/AIDS was conducted among people from Bangladesh seeking work overseas (N = 300), during February, 1997 and March, 1997. Only 26% of the respondents knew of AIDS and out of 13 basic facts concerning HIV/AIDS the mean score of the sample was 1.63 correct responses. Most of those who knew of HIV had some false beliefs about the mode of HIV transmission, for example, believing that HIV could be contracted by touching an AIDS patient, or sharing bathing facilities or eating utensils. Sex with brothel-based commercial sex workers (100%), sharing contaminated needles (93.6%) and blood transfusion from infected individuals (93.6%) were seen as the main route of HIV transmission. Printed media (69%) was the main source of AIDS information. Multiple logistic regression analysis showed that having a non-agricultural occupation (P < 0.04), being resident in Dhaka, Chandpur, Noakhali, Comilla, and Chittagong (P < 0.01), being in the habit of reading newspapers (P < 0.05), using condoms (P < 0.04), having heard about condoms (P < 0.003), having seen condoms (P < 0.005) and knowing where to buy condoms (P < 0.0005) were significantly associated with AIDS awareness. There is insufficient AIDS awareness among overseas job seekers which calls for public initiatives to provide AIDS information to them before they leave Bangladesh to work abroad.

Adult↗
PubMed1999

Regulatory network of mitomycin C action in human colon cancer cells.

A network composed of activation and inactivation pathways to regulate mitomycin C (MMC) action is suggested to exist in human cancer cells. COLO201 colon cancer cells were stably transfected with human NQO1 cDNA that encodes NAD(P)H:quinone oxidoreductase (DT-diaphorase, DTD), and a clonal cell line with about 57-fold elevated DTD activity was obtained. Northern analysis revealed that expression of the NADPH:cytochrome P450 reductase (P450 reductase) gene was decreased in the transfectant, COLO201/NQO1, associated with the increase of NQO1 expression. Biochemical characterization of the cells showed a significant increase of the glutathione (GSH) content concomitantly with the decrease of the P450 reductase activity. As a result of these coordinated modulations, sensitivity of COLO201/NQO1 to MMC was not increased as compared to the parent cells. Analyses of inhibition by specific inhibitors of DTD, P450 reductase and glutathione S-transferase (GST) in 5 human colon cancer cell lines including the transfectant showed that DTD and P450 reductase play significant roles in MMC activation in cells with sufficiently high DTD activity and with marginal DTD activity, respectively. In contrast, GST appeared to participate in MMC inactivation in cells with a high level of GST activity. These results indicated that DTD, P450 reductase, GSH and GST may act together compensatively or competitively, depending on their levels in cells, to determine the cellular sensitivity to MMC.

Antibiotics, Antineoplastic↗
PubMed1999

[The year 2030: dawn of the millennium of the profession: nursing--a prospective view of nursing undergraduate students].

Study based on testament-letters written by freshmen students of the undergraduate course in Nursing, who should imagine to be in the year 2030. Everything imagined by these students and that might have happened in the three earlier decades was the subject of this study, such as professional and nurses achievements, outbreak of cure for illnesses, social prestige and positions.

Adolescent↗
PubMed1999

Dihydropyrimidine dehydrogenase, multidrug resistance-associated protein, and thymidylate synthase gene expression levels can predict 5-fluorouracil resistance in human gastrointestinal cancer cells.

Gene expression of dihydropyrimidine dehydrogenase (DPD) and newly multidrug resistance-associated protein (MRP) was found to correlate well with primary 5-FU resistance in 7 human gastrointestinal cancer cell lines. Although mRNA and protein levels of thymidylate synthase (TS) did not relate to the resistance, 5-FU treatment revealed a remarkable increase of TS expression. Such enhanced TS expression was more significant than DPD and MRP, and observed less in 5-FU sensitive cells. DPD and MRP expression levels can predict primary 5-FU resistance, and TS may be a potent predictor of cellular 5-FU resistance after 5-FU treatment.

ATP-Binding Cassette Transporters↗
PubMed1999

The clinical epidemiological investigation of diagnostic modalities in breast cancer detection--a comparison of ultrasonography and mammography.

We reviewed the medical records and images of 39 women with palpable breast masses, including 18 cases with breast cancer and 21 cases with benign breast mass, to compare diagnostic accuracy and clinical agreement between ultrasonography and mammography in breast cancer detection. We showed that the operating characteristics of ultrasonography, including sensitivity, specificity and positive likelihood ratio, were superior to that of mammography. We also confirmed that the established malignant criteria for malignancy, including lobulated shape, irregular contour and non-uniform internal echo in ultrasonography, and stellate mass in mammography, were statistically significant in distinguishing breast cancer from benign breast lesion. Moreover, the interobserver agreement kappa of ultrasonography and mammography were 0.64 and 0.59, respectively. Ultrasonography was also superior to mammography in attaining clinical agreement between the different observers in breast cancer detection.

Breast Neoplasms↗
PubMed1999

Low-dose cisplatin and 5-fluorouracil in combination can repress increased gene expression of cellular resistance determinants to themselves.

The synergistic mechanism of cisplatin (CDDP) and 5-fluorouracil (5-FU) in combination remains unclear, despite its substantial antitumor activity, which has been demonstrated clinically. To clarify the mechanism(s), we determined the sensitivity or resistance factors to either drug in seven gastrointestinal cancer cell lines and then analyzed the altered gene expression after different exposures to CDDP and 5-FU. At the basal gene expression level, glutathione S-transferase pi (GSTpi) expression correlated with the observed resistance to CDDP, whereas dihydropyrimidine dehydrogenase (DPD) and multidrug resistance-associated protein (MRP) expression was related to 5-FU resistance. GSTpi, DPD, and MRP expression increased in response to the respective drug, but they also increased in response to the other drug as well. Additionally, 5-FU revealed a drastically increased thymidylate synthase (TS) gene expression in 5-FU-resistant cells. However, the increasing actions of CDDP and 5-FU on GSTpi, DPD, MRP, and TS expression varied according to the exposure time, concentration, and schedule. A low concentration of CDDP (1 microg/ml, 30 min) followed by 5-FU (0.5 microg/ml, 72 h) was found to cause a less increased expression of DPD, MRP, GSTpi, and TS than either drug alone, thus resulting in synergistic cytotoxicity in 5-FU-resistant COLO201 and CDDP-resistant HCC-48 cells. The sequential combination of CDDP and 5-FU inhibited the growth of human normal renal proximal tubule cells by less than 20%. Low concentrations of CDDP followed by continuous exposure to 5-FU can repress increased gene expression related to both drug resistances, thereby being synergistically cytotoxic in human gastrointestinal cancer cells.

ATP-Binding Cassette Transporters↗
PubMed1999

[Methicillin-resistant Staphylococcus aureus subdural abscess in an elderly patient with dementia].

A 74-year-old man was admitted to our hospital because of a fever of 38.2 degrees C and drowsiness. Two months before admission, he was admitted to another hospital with the diagnosis of Alzheimer's disease. One week before admission, he had a fever which was judged to be due to pyelonephritis. Because imipenem cilastatin and minocycline were not effective in relieving symptoms, he was transferred to our hospital. Methicillin-resistant Staphylococcus aureus (MRSA) was cultured from the blood, and vancomycin was started on the 5th hospital day. Because of the persistent fever and signs of inflammation, Gallium-scintigraphy was performed, showing abnormal accumulation in the left fronto-parietal region of the brain and the sacral region. Enhanced brain CT revealed a crescentic low density area and a fine, intense line of enhancement in the left fronto-parietal region. An emergency drainage of abscess was performed via single left fronto-parietal burr hole. A slightly yellowish, bloody, purulent fluid was obtained. The subdural space was irrigated with saline containing antibiotics and a drain was inserted. MRSA was cultured from the obtained fluid. The fever gradually subsided and drowsiness disappeared. He had had decubitus ulcer, stage I on the surface, in the sacral region, which later turned out to have unexpectedly deep undermining lesion reaching to periosteum. MRSA was cultured from this decubitus lesion. MRSA which entered into blood stream from the decubitus site might have been implanted in the subdural hematoma. Thus, subdural abscess should be kept in mind as an active differential diagnosis in elderly patients with fever and drowsiness.

Aged↗
PubMed1998

Effect of 360 degrees and 180 degrees rotation SPET acquisitions on myocardial polar map: comparison of 201Tl-, 99Tcm- and 123I-labelled radiopharmaceuticals.

Both 360 degrees and 180 degrees rotation acquisition methods have been used in myocardial single photon emission tomography (SPET) studies. We compared both methods using 201Tl, 99Tcm and 123I radiopharmaceuticals with phantoms and clinical models. Myocardial phantom studies with anterior and inferior defects were performed using 201Tl, 99Tcm and 123I. Clinical models of 14 typical situations, including normal subjects, patients with anterior or inferior defects and a high right hemi-diaphragm, were studied. The radiopharmaceuticals were 201Tl, 99Tcm-sestamibi, 123I-BMIPP and 123I-MIBG. Four sets of 180 degrees anterior rotation data with starting angles of (A) posterior, (B) LPO 30 degrees, (C) LPO 60 degrees and (D) left lateral direction were generated and compared with 360 degrees rotation SPET. A polar map display was used for quantification. In phantom studies, the defect contrast on the map was higher in the anterior defect with 180 degrees rotation than with 360 degrees rotation. However, it was decreased in the inferior defect, particularly with 201Tl, because of decreased wall activity around the defect. In the patient model with anterior or inferior defects, the defect contrast was improved with 180 degrees SPET by up to 10%. A slight decrease in the normal region was also noted in the 180 degrees reconstruction. The effect of diffuse liver activity on the inferior region depended on the rotation range. A patient with a high right hemi-diaphragm showed a lower inferior count with 360 degrees SPET. In conclusion, the 360 degrees acquisition was superior to the 180 degrees acquisition in the phantom with defects. Clinically, the quantitative differences in radionuclide types (99Tcm, 123I or 201Tl) were not significant for quantifying a moderate degree (50-60% of peak count) of defect. However, we note quantitative variation depending on the rotation range in the 180 degrees method.

3-Iodobenzylguanidine↗
PubMed1998

Myocardial fatty acid imaging with 123I-labelled 9-methyl-branched pentadecanoic acid (9MPA) using SPET.

123I-labelled 15-(p-iodophenyl)-9-(R,S)-methylpentadecanoic acid (9MPA) is a modified long-chain fatty acid that shows some beta-oxidation. Some basic aspects of this fatty acid, including myocardial uptake, distribution, clearance and differences from 201Tl myocardial perfusion, have yet to be evaluated. An average of 150 MBq of 123I-9MPA was injected intravenously into 16 patients with coronary artery disease. Planar images were obtained 45, 120 and 240 min post-injection, and single photon emission tomography (SPET) was performed at the initial (5 min), middle (45 min) and late (120 min) phases after injection. Myocardial uptake and clearance were evaluated by planar imaging, and a segmental comparison between 123I-9MPA and reinjection or resting 201Tl was performed on the SPET images. 123I-9MPA showed good uptake between 5 and 60 min, but a severe decrease was seen after 120 min in three (19%) patients. The heart-to-mediastinum ratio was 1.68 +/- 0.19, 1.55 +/- 0.19 and 1.40 +/- 1.40 at 45, 120 and 240 min, respectively. The washout rate after background subtraction was 28% for 45 min to 2 h and 47% for 45 min to 4 h. The segmental comparison (n = 182) between 123I-9MPA and 201Tl showed complete agreement of 72, 75 and 65% at 10, 45 and 120 min, respectively. The grading of the uptake of 123I-9MPA was less than that of 201Tl in 20-30% of the segments indicating myocardial fatty acid metabolic impairment relative to perfusion. The regional clearance from 5 to 120 min in the reduced-count region was lower than that in the normal region (28 +/- 7% vs 36 +/- 8%, P < 0.01). All 123I-9MPA SPET images showed good contrast if the data were acquired within 60 min. Based on the clearance of 123I-9MPA from the myocardium, imaging within 120 min is desirable. A mismatch of fatty acids and perfusion was seen in one-quarter of patients, and differential regional clearance may be clinically significant and should be investigated.

Adult↗
PubMed1998

Rhenium-186-mercaptoacetyltriglycine-labeled monoclonal antibody for radioimmunotherapy: in vitro assessment, in vivo kinetics and dosimetry in tumor-bearing nude mice.

Stability and immunoreactivity of 186Re-labeled monoclonal antibody were examined, and its in vivo kinetics was investigated in tumor-bearing Balb/c nu/nu female mice to assess the feasibility of using it in radioimmunotherapy (RIT). A murine IgG1, A7, against a 45 kD glycoprotein in human colon cancer was radiolabeled with 186Re by using a chelating method with a mercaptoacetyltriglycine (MAG3). 186Re-MAG3 complex was conjugated to A7 after esterification of 186Re-MAG3 with tetrafluorophenol (TFP). The efficiency of 186Re-MAG3-TFP production and the labeling efficiency of A7 were 51-59% and 57-60%, respectively. Immunoreactivity of purified 186Re-MAG3-A7 was 68.2% at infinite antigen excess. In 0.9% NaCl at 4 degrees C, the radioactivity (12.7 MBq/mg, 3.55 MBq/ml) dissociated with time from 186Re-MAG3-A7 as a small molecular weight moiety because of autoradiolysis. The addition of ascorbic acid, 5 mg/ml, as a radioprotectant or storage at -80 degrees C could effectively prevent the radiolysis of 186Re-MAG3-A7 for 7 days. Immunoreactivity of 186Re-MAG3-A7, 6.70 MBq/mg (6.66 MBq/ml), stored in the presence of ascorbic acid was well retained up to 8 days after the preparation. In colon cancer xenografted mice, 31.0% of the injected dose/g of 186Re-MAG3-A7 had accumulated in the tumors at 24 h postinjection. Estimated radiation dose to tumors was 14.9 cGy/37 kBq up to 8 days postinjection which was 12-fold greater than the whole-body radiation dose. These in vivo characteristics were superior to those of A7 labeled with radioiodine, affording greater therapeutic ratios than 131I-A7. Because of the better image quality of 186Re-MAG3-A7 as well as more favorable dosimetry, 186Re-MAG3-A7 would be a better choice for RIT of colon cancer than 131I-A7. These results indicated the feasibility of RIT with 186Re-MAG3-A7, though the prevention of radiolysis of the labeled antibody should be considered.

Animals↗
PubMed1998

Persistent distension and enhanced diffusive extravasation of tumor vessels improved uniform tumor targeting of radioimmunoconjugate in mice administered with angiotensin II and kininase inhibitor.

Induced hypertension with angiotensin II (AT-II) and the inhibition of kininase with enalapril maleate may increase the tumor targeting of radiolabeled monoclonal antibodies (MAbs). We previously found that short-period infusion of 2.0 microg/kg/min of AT-II enhanced tumor targeting of MAb without an impact on normal tissue distribution. In this study, we aimed to optimize the manipulation with these agents, and examine the possible mechanism of their effects on MAb distribution. Effect of the manipulation on tissue circulation was assessed in mice bearing colon cancer xenografts by 201Tl and 99mTc-human serum albumin (HSA) as markers of tissue blood flow and tissue blood volume and/or vascular permeability. A dose finding study of enalapril ranging from 3 to 300 microg showed that 30 microg of enalapril in combination with AT-II infusion produced the best improvement in tumor uptake of 99Tc-HSA without altering 201Tl distribution, suggesting that the increase of vascular permeability was caused by enalapril. AT-II infusion for longer than 1 h affected renal blood flow and caused subcutaneous edema. Tumor uptake of (111)In-A7, a murine IgG1, was 1.62-fold improved 72 h postinjection (P < 0.001) and intratumoral distribution became uniform with 2.0 microg/kg/min of AT-II for 1 h and 30 microg of enalapril. Vessels in manipulated tumors were distended even 48 h after the cessation of AT-II infusion. In conclusion, it was suggested that persistent distension of tumor vessels and the increase of diffusive extravasation of MAb caused by short-period-induced hypertension and inhibition of bradykinin degradation produced favorable effect for the MAb distribution in tumors.

Angiotensin II↗
PubMed1998

Prediction of prognosis in peripheral facial nerve paralysis using submandibular gland scintigraphy.

UNLABELLED: In this study, we evaluated the ability of submandibular gland scintigraphy to predict the prognosis of peripheral facial nerve paralysis. METHODS: Submandibular gland scintigraphy was performed in 78 patients with acute peripheral facial nerve paralysis. After injection of 180-370 MBq [99mTc]pertechnetate, serial 1-min images were acquired for 25 min. At 15 min after injection of radionuclide, ascorbic acid was administered intraorally to stimulate salivary secretion. Regions of interest were set manually on both submandibular glands, and time-activity curves were generated. The ratios of peak count density (PCR) and washout (WR) of the affected side to the normal side were calculated. Parameters of > or = 0.8 suggested normal affected submandibular function and indicated a good prognosis. RESULTS: Complete recovery of facial nerve paralysis was observed in 52 of 78 patients. The sensitivity, specificity and accuracy of PCR for a good prognosis were 79%, 50% and 69%, and those of WR were 85%, 77% and 82%, respectively. Positive and negative predictive values for a good prognosis were 76% and 54% in PCR and 88% and 71% in WR, respectively. When WR obtained within 14 days of the onset was used, positive and negative predictive values for a good prognosis were 94% and 73%, respectively. None of the eight patients who had values of <0.8 for both parameters within 14 days of the onset recovered completely. CONCLUSION: Submandibular gland scintigraphy can serve as a reliable indicator to predict the prognosis of acute peripheral facial nerve paralysis in its early symptomatic period.

Acute Disease↗
PubMed1998

[Simple kinetic analysis of 99mTc-GSA by direct integral linear least square regression method: calculation of hepatic blood flow and receptor index based on three-compartment model].

To obtain both hepatic blood flow and an index of asialoglycoprotein receptor amount by simple calculation in the asialoglycoprotein receptor imaging with 99mTc-DTPA-Galactosyl Human Serum Albumin (99mTc-GSA), we have tested the applicability of the direct integral linear least square regression (DILS) method based on a linear 3-compartment model (Bronqvist, 1984) to the kinetic analysis of 99mTc-GSA scintigraphy. DILS method can provide hepatic blood flow (k1) and the product of receptor amount and forward binding rate constant (k1k3/k2) as a receptor index, without requiring iterative calculation and initial estimates of the parameters. To compare DILS method with nonlinear least square regression (NLS) method as a standard, data from 35 patients with liver dysfunction were analyzed by both methods. The effect of the data noise to parameter estimate were simulated, and both DILS and NLS method could provide reliable parameter estimate which is relatively insensitive to the data noise. In estimated model parameters, both hepatic blood flow (k1) and the receptor index (k1k3/k2) showed significant correlation between 2 methods (r2 = 0.96, p < 0.0001; r2 = 0.99, p < 0.0001, respectively). We concluded that DILS method was comparable to NLS method in determination of the model parameters and could be useful in the asialoglycoprotein receptor imaging.

Adult↗
PubMed1997

Molecular targeting of mitomycin C chemotherapy.

In 10 human cancer cell lines, the activity of mitomycin C (MMC) was found to be determined by an interplay between activation by DT-diaphorase (DTD) and inactivation by glutathione S-transferase (GST). NADPH/cytochrome P-450 reductase was not responsible for MMC activation and expression of MDRI (Mr 170,000 P-glycoprotein), and MRP (multidrug resistance-associated protein) genes did not relate to MMC resistance. Gene expression analysis for NQO1 (DTD gene) and GSTpi predicted which enzyme activity predominated in a cell line, except K562 and K562/DOX. For tumors with DTD activity only, MMC given by itself was most active. In cell lines in which DTD action was predominant, tumor selectivity was achieved by enhancing DTD-mediated activation with m-iodobenzylguanidine and hyperglycemia, which reduced the intra-tumoral pH. KW2149, a novel MMC analogue activated by glutathione, was most active against tumors in which GSTpi predominated. These various enzyme-specific effects could be observed even in cell lines derived from tumors with multidrug resistance. Such MMC treatment based on cell enzymology may enhance significantly MMC efficacy, helping to overcome multidrug resistance.

Animals↗