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Biomedical subjects

K Suga

Publications and source records attributed to K Suga.

At least 55 records · Page 3Linked to original sources
PubMed2000

Different expression patterns of Bcl-2 family genes in breast cancer by estrogen receptor status with special reference to pro-apoptotic Bak gene.

Oncogenic and anti-apoptotic Bcl-2 is expressed much less in estrogen receptor alpha (ERalpha) negative breast cancers, which show more malignant phenotypes, than ERalpha-positive, indicating that some other Bcl-2 family member(s) are involved in the apoptotic balance of the cancer cells. We first analyzed mRNA expression of pro-apoptotic Bak and Bax along with that of anti-apoptotic Bcl-2 and Bcl-xL, using breast cancer specimens of 27 patients. Bak mRNA was expressed much less in ERalpha negative breast cancers, along with reduced expression of Bcl-2. Immunostaining of sections of 108 patients confirmed the observation. Next, stable transformants of MCF-7 cells with sense Bak expression vector showed fewer colonies in soft agar compared with the parental cells, while stable introduction of antisense Bak vector enhanced colony formation at lower estradiol concentrations. The reduction of Bak may play important roles in malignant development of breast cancer to acquire estrogen independency, counteracting the reduced Bcl-2.

Apoptosis↗
PubMed2000

Computed tomography of emphysema following tooth extraction.

Subcutaneous and tissue space emphysema following surgical extraction of mandibular third molars is a rare and serious complication of dental surgery. Recognition of mediastinal emphysema following surgical extraction is difficult because there are no absolute clinical symptoms and signs. We present two cases of emphysema following extraction of a lower third molar and discuss the contribution of CT to the early recognition of the presence and spatial migration of air and to clinical management.

Adult↗
PubMed2000

Control of antibody-antigen interaction using anion-induced conformational change in antigen peptide.

The binding of a monoclonal antibody to an epitope peptide was controlled by the conformational change of the epitope peptide induced by anions. We synthesized peptides in which the epitope sequence DTYRYI for the monoclonal antibody AU1 is located between amphiphilic peptides (KKLL)n and (LLKK)n. In the absence of an appropriate anion, the peptide was in a random coil state and the epitope was linear. In contrast, in the presence of an appropriate anion, the peptide exhibited an anti-parallel alpha-helical structure and the epitope was subsequently 'bent'. In the presence of 41 microM triphosphate, the association constant between the antibody and the peptide was decreased by one order of magnitude in the case of n = 3 and at least three orders of magnitude in the case of n = 4 or 5. Oligo-DNAs, as anions, dissociated the antibody-peptide complex, whereas triphosphate did not. The DNA concentrations required for 50% dissociation of the antibody-peptide complex at pH 7.5 were 4x10(-8), 1x10(-7) and 6x10(-6) M for decamer, octamer and hexamer DNA, respectively.

Amino Acid Sequence↗
PubMed2000

Coexisting renal vein thrombosis and bilateral adrenal hemorrhage: renoscintigraphic demonstration.

A rare case of simultaneous renal vein thrombosis and bilateral adrenal hemorrhage is presented, showing the utility of Tc-99m DTPA and DMSA renal scans to identify the condition and to assess renal function. The characteristic appearances of suprarenal tracer-free areas encircled by peripheral radioactive rims over the inferiorly displaced kidneys on a Tc-99m DTPA renal scan, and that of the flattened upper poles of the kidneys on a Tc-99m DMSA scan, were pathognomonic and strongly indicative of bilateral adrenal hemorrhage. These two scans also showed markedly diminished tracer uptake in the poorly functioning right thrombosed kidney. Follow-up imaging using these two renal scans well demonstrated the functional and morphologic alterations and recovery of the kidneys.

Adrenal Gland Diseases↗
PubMed2000

Tc-99m MIBG imaging in a huge clinically silent pheochromocytoma with cystic degeneration and massive hemorrhage.

I-131 metaiodobenzylguanidine scintigraphy showed marked accumulation in the walls of a clinically silent, huge cystic adrenal mass with a prominent hemorrhage in a 48-year-old man. Although a careful reexamination of the histologic specimen finally lead to a diagnosis of pheochromocytoma, the appearances of this mass on computed tomography and magnetic resonance imaging were not specific for this neoplasm, and even pathologic analysis initially indicated, incorrectly, that this lesion was a hemorrhagic hemangioma. This case shows that I-131 metaiodobenzylguanidine scintigraphy is useful for correctly diagnosing an adrenal mass with prominent cystic or hemorrhagic degeneration.

3-Iodobenzylguanidine↗
PubMed2000

Liver involvement in hereditary haemorrhagic telangiectasia: assessment with 99Tcm-phytate radionuclide angiography and 123I-IMP transrectal portal scintigraphy.

Abnormal hepatic haemodynamics and function in a 43-year-old woman with hereditary haemorrhagic telangiectasia (HHT) were evaluated using 99Tcm-phytate angiography and iodine-123-iodoamphetamine transrectal portal scintigraphy. Radionuclide angiography demonstrated hyperdynamic perfusion of the liver owing to intrahepatic arteriovenous fistulae (AVF), entry of tracer into the systemic circulation through intrahepatic portosystemic shunts and an increase in recirculating blood flow caused by these vascular disorders. Heterogeneous distribution of tracer also suggested the presence of chronic hepatic injury. Transrectal portal scintigraphy showed large portosystemic shunts. Other imaging techniques confirmed the presence of the AVF but failed to identify the portosystemic shunts. Non-invasive radionuclide studies are helpful in the evaluation of hepatic involvement of HHT.

Adult↗
PubMed2000

L-Lysine production by exponential feeding of L-threonine.

The effect of L-threonine feeding in the production phase on L-lysine production by Brevibacterium flavum, which requires L-homoserine or L-threonine for cell growth, was investigated considering the concerted inhibition by L-threonine plus L-lysine, and the metabolism related to lysine production. Exponential feeding of L-threonine increased L-lysine production to 70 g/l about three times that without feeding. From the analysis of the metabolic flux, carbon flux of L-lysine synthesis pathway in the production phase after L-threonine feeding was higher than that in the growth phase. The results show that feeding of an inhibitory substance may increase the production, especially when the substance is necessary for the continuation of cell growth and/or production.

Journal Article↗
PubMed2000

Cryoprotective activities of group 3 late embryogenesis abundant proteins from Chlorella vulgaris C-27.

The nucleotide sequence of hiC12, isolated as a cDNA clone of hardening-induced Chlorella (hiC) genes, was identified. The clone encodes a late embryogenesis abundant (LEA) protein having six repeats of a 11-mer amino acid motif, although in a slightly imperfect form. To overexpress the hiC61) and hiC12 genes, their coding regions were PCR amplified and subcloned into a pGEX-1lambdaT vector. The HIC6 and HIC12 proteins were expressed as GST fusion proteins in E. coli, then purified. The two HIC proteins were found to be effective in protecting a freeze-labile enzyme, LDH, against freeze-inactivation. On a molar concentration basis, they were about 3.1 x 10(6) times more effective in protecting LDH than sucrose and as effective as BSA. Cryoprotection tests with five kinds of chain-shortened polypeptides, synthesized based on the 11-mer amino acid motif of the HIC6 protein showed that the cryoprotective activity decreased with a decrease in the repeating units of the 11-mer motif. In fact, cryoprotective activities of three kinds of single 11-mer amino acids were very low even at high concentrations. All the results suggested that the sufficiently repeated 11-mer motif is required for the cryoprotective activities of Chlorella LEA proteins.

Amino Acid Sequence↗
PubMed2000

Interactions of regional respiratory mechanics and pulmonary ventilatory impairment in pulmonary emphysema: assessment with dynamic MRI and xenon-133 single-photon emission CT.

STUDY OBJECTIVES: Dynamic MRI and (133)Xe single-photon emission CT (SPECT) were used to directly evaluate the interaction of regional respiratory mechanics and lung ventilatory function in pulmonary emphysema. METHODS: Respiratory diaphragmatic and chest wall (D/CW) motions were analyzed by sequential MRI of fast-gradient echo pulse sequences during two to three respiratory cycles in 28 patients with pulmonary emphysema, including 9 patients undergoing lung volume reduction surgery (LVRS). The extent of air trapping in the regional lung was quantified by the (133)Xe retention index (RI) on three-dimensional (133)Xe SPECT displays. RESULTS: By contrast to healthy subjects (n = 6) with regular, synchronous D/CW motions, pulmonary emphysema patients showed reduced, irregular, or asynchronous motions in the hemithorax or location with greater (133)Xe retention, with significant decreases in the maximal amplitude of D/CW motions (MADM and MACWM; p < 0.0001 and p < 0.05, respectively). The removal of (133)Xe retention sites by LVRS effectively and regionally improved D/CW motions in nine patients, with significant increases in MADM and MACWM (p < 0.01 and p < 0.001, respectively). In a total of 40 studies of the 28 patients including post-LVRS studies, normalized MADM and MACWM correlated with percent predicted FEV(1) (r = 0.881, p < 0.0001; and r = 0.906, p < 0.0001, respectively), and also with (133)Xe RI in each hemithorax (r = -0.871, p < 0 0.0001; and r = -0.901, p < 0 0.0001, respectively.) CONCLUSIONS: This direct comparison of regional respiratory mechanics with lung ventilation demonstrated a close interaction between these impairments in pulmonary emphysema. The present techniques provide additional sensitivity for evaluating pathophysiologic compromises in pulmonary emphysema, and may also be useful for selecting resection targets for LVRS and for monitoring the effects.

Aged↗
PubMed2000

Prolapsing gyrus rectus as a cause of progressive optic neuropathy.

The pathogenesis of optic neuropathy caused by neurovascular compression or by similar mechanisms is unclear. Thin-slice magnetic resonance (MR) imaging was performed in 69 patients with optic neuropathy without demonstrable ophthalmological lesions (57.0 +/- 17.1 years of age) and 102 normal subjects (57.7 +/- 13.9 years of age). The MR imaging features were classified into "no compression" by the internal carotid artery (ICA), "compression" by the ICA, "no contact" with the anterior cerebral artery (ACA) or the gyrus rectus, "contact" with either or both, "compression" by the ACA, and "compression" by the gyrus rectus. The Spearman correlation coefficients were calculated between patients or controls, the MR classification, and the age, and the number of patients in each MR classification were evaluated by the chi 2 test. Five of the 69 patients with rapidly progressive symptoms were operated on via the frontotemporal approach. The MR imaging feature of "compression" by the gyrus rectus was the best predictor of optic neuropathy (Spearman correlation coefficients rho = -0.23646, p < 0.0018). This MR imaging feature was observed in 38 of 69 patients and in 32 of 102 controls (p = 0.002). Compression of the nerve by the gyrus rectus or the ACA was confirmed in all five operated cases. Decompression of the nerve was fully achieved in four of the five patients, and their symptoms have not progressed since then. Optic neuropathies due to compression by the prolapsing gyrus rectus are not well understood. Such neuropathies may be detected by MR imaging.

Adolescent↗
PubMed2000

A new concept of tumor promotion by tumor necrosis factor-alpha, and cancer preventive agents (-)-epigallocatechin gallate and green tea--a review.

The study of tumor promotion in rodent carcinogenesis using chemical tumor promoters has revealed various tumor promotion pathways, such as the 12-O-tetradecanoylphorbol-13-acetate (TPA) pathway mediated through activation of protein kinase C, and the okadaic acid pathway mediated through inhibition of protein phosphatases 1 and 2A (PP-1 and PP-2A). We previously demonstrated that application of TPA and okadaic acid induced tumor necrosis factor-alpha (TNF-alpha) gene expression in mouse skin, but that tautomycin, which is an inhibitor of PP-1 and PP-2A and not a tumor promoter on mouse skin, did not. Moreover, we found that TNF-alpha stimulated transformation of BALB/3T3 cells initiated with 3-methylcholanthrene 1,000 times stronger than did TPA (Cancer Res. 53, 1982-1985, 1993). This evidence demonstrates a link between the okadaic acid pathway and the endogenous tumor promotion pathway of TNF-alpha. Recently we presented the first evidence that tumor promotion in TNF-alpha(-/-) mice was significantly depressed compared with TNF-alpha(+/+) mice. Thus, in human carcinogenesis, we think that TNF-alpha and other inflammatory cytokines in preneoplastic lesion stimulate tumor promotion and progression of initiated cells as well as premalignant cells. The first part of this paper reports on this TNF-alpha tumor promotion pathway. In the second part, we report a promising screening method for cancer preventive agents, based on evidence that pretreatment with agents such as tamoxifen, sulindac, 1alpha, 25-(OH)2 vitamin D3, quercetin, caffeic acid phenethyl ester, and (-)-epigallocatechin gallate (EGCG) commonly inhibited TNF-alpha release from BALB/3T3 cells induced by okadaic acid. EGCG, the main constituent of Japanese green tea, and green tea itself are acknowledged cancer preventives in Japan, and this paper presents evidence of their effectiveness in both a high-risk group and the general population.

Animals↗
PubMed2000

[Respiratory nuclear medicine for general radiologist].

This paper describes some of the basic pathophysiologic information required for the interpretation of pulmonary perfusion and ventilation scintigraphy, i.e., perfusion reduction associated with hypoxic vasoconstriction due to ventilatory dysfunction, vascular beds in the upper lung as a reserve of perfusion, stripe sign, fissure sign, characteristic MAA distributions in right-to-left shunt, and different tracer distributions in the lung according to tracer sizes. The utility of perfusion and xenon-133 SPECT in the evaluation of cross-sectional lung function in various disorders is also emphasized. Also described are the utility of Tc-99m-DTPA lung scan in the evaluation of alveolar permeability, Ga-67 scan in the diagnosis of sarcoidosis, bone scans in the diagnosis of pulmonary metastatic calcifications and stress rib fractures, lymphoscintigraphy in the diagnosis of chylothorax, and Tc-99m-HSA scan in the detection of bleeding sites.

Humans↗