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Biomedical subjects

T Ueda

Publications and source records attributed to T Ueda.

At least 217 records · Page 12Linked to original sources
PubMed1993

Tertiary structural analysis of Escherichia coli lysine tRNA.

It has been suggested that Escherichia coli lysine tRNA (E. coli tRNA(Lys)) has an unusual anticodon loop structure, judging from the abnormal CD pattern derived from 5-methylaminomethyl-2-thiouridine (mnm5s2U) located at the first position of the anticodon of the tRNA. Here, the structure of E. coli tRNA(Lys) was analysed by chemical modification and nuclear magnetic resonance (NMR) of the imino protons. The chemical probing approach showed that the anticodon arm region forms the ordinary stem-and-loop structure as expected from the standard clover-leaf structure, because N7 of G30, N3 of C40, N7 of A41 and N7 of A42 were protected under a native condition. By using the heteronuclear 15N-1H single quantum coherence (HSQC) spectra of 15N-labeled E.coli tRNA(Lys) and the analyses of the nuclear Overhauser effects (NOE) between the imino protons of non labeled E.coli tRNA(Lys), the imino protons in the acceptor stem was assigned, which indicates that the acceptor stem exists in an usual form. The tertiary base-base interactions was also detected. Thus, E.coli tRNA(Lys) seems to maintain a similar structure to the ordinary L-shaped tertiary structure, as a whole. The fine structure of the anticodon loop is now being analyzed.

Anticodon↗
PubMed1993

Tertiary structures of mitochondrial tRNAs having characteristic secondary structures.

Some of the animal mitochondrial (mt) tRNAs are thought to have unusual secondary structures as inferred from the mt DNA sequence analysis. To obtain information on the relationship between the unusual secondary and tertiary structures and function of these mt tRNAs at the RNA level, we have analyzed the structure of bovine mt serine tRNAs and obtained the following results. 1) Using the novel secondary structure proposed on the basis of enzymatic probing and phylogenetic comparison and the known tertiary structure of yeast tRNA(Phe), a tertiary structural model of tRNA(Ser) specific for UCU/C/A/G codons was constructed by a computer modeling. In the proposed model, one-base-pair elongation of anticodon stem compensated for the deletions in some of the loop regions of this tRNA, and the model maintained the topological relationship between the anticodon and 3'-CCA terminus as nearly the same as that of yeast tRNA(Phe). The results of chemical modification of this tRNA supported the proposed model. 2) For NMR analysis of tRNA(Ser) specific for AGU/C codons and lacking the D stem, a large scale preparation of the unmodified tRNA transcript has been performed by the use of an in vitro T7 transcription system.

Animals↗
PubMed1993

Thallium-201 SPECT for predicting histological types of meningiomas.

Early and delayed 201Tl SPECT studies were performed on 13 patients with intracranial meningiomas, which were classified in three groups according to their histological types: meningothelial (n = 7); transitional and fibroblastic (n = 3); and malignant types (n = 3). The early uptake indices (UI, ratios of average counts/pixel in the lesion to those of the contralateral area on early images) were relatively high in all types: meningothelial meningiomas, 5.75 +/- 2.16 (mean +/- s.d.); transitional and fibroblastic meningiomas, 4.69 +/- 0.54; and malignant meningiomas, 7.10 +/- 3.72. There were no statistical differences in relation to histological type. The delayed uptake indices were 2.65 +/- 0.89, 3.37 +/- 1.02, and 5.16 +/- 1.62, respectively. Statistically, the delayed UI of meningothelial meningiomas were lower than those of malignant types (p < 0.05). The retention indices (RI, ratios of delayed to early UI) were 0.48 +/- 0.08, 0.79 +/- 0.16, and 0.84 +/- 0.16, respectively. The RI of the meningothelial type were also statistically lower than those of the other two groups (p < 0.05). There were no statistically significant differences between transitional plus fibroblastic types and malignant meningiomas. We conclude that 201Tl exhibits early high accumulations in all types of meningiomas, but its retention rates probably differ according to histological types, and a high retention index is predictive of the malignant potential in a meningioma.

Adult↗
PubMed1993

Early and quantitative detection of cisplatin-induced nephrotoxicity by measurement of plasma PSP (phenolsulfonphthalein) half-life in rats.

Renal function following cisplatin injection in rats was assessed by measuring the half-life of plasma PSP. Changes in BUN, creatinine, plasma PSP half-life and urinary N-acetyl-beta-D-glucosaminidase (NAG) levels were determined in rats treated with 6.5 mg/kg i.v. of cisplatin. The highest values of BUN and creatinine were both observed on day 5. Half-life of plasma PSP was significantly prolonged on days 2 through 5 and reached a peak value on day 3. A significant increase in urinary NAG levels appeared on day 2 and the peak value was demonstrated on day 3. BUN, creatinine and plasma PSP half-life were also determined on days 3 and 5 following several doses of i.v. cisplatin. A dose-related increase in plasma PSP half-life was observed on day 3, while dose-related increases in BUN and creatinine levels were found on day 5. The evaluation of cisplatin-induced nephrotoxicity by the plasma PSP test was clearly superior for early detection compared with conventional renal function tests using BUN and creatinine.

Animals↗
PubMed1993

[A case of intracranial malignant melanoma with increased uptake of IMP in SPECT].

A patient with intracranial malignant melanoma was assessed by 123I-IMP SPECT. Early image, performed 30 minutes after intravenous injection of 111 MBq 123I-IMP, demonstrated an accumulation similar to normal gray matter-defect. Delayed image, performed 4-hour after injection, demonstrated increased accumulation of 123I-IMP. 123I-IMP SPECT, especially delayed scan, was valuable for qualitative diagnosis of intracranial malignant melanoma.

Adult↗
PubMed1993

[Determining factors of successful percutaneous transvenous mitral commissurotomy and eligible indications for the procedure].

The aim of this report is to investigate the factors which influence mean left atrial pressure (LAP) after percutaneous transvenous mitral commissurotomy (PTMC) and the characteristics of patients in whom PTMC is most effective. Fifty one patients with symptomatic mitral stenosis underwent PTMC. The patients included 8 males and 43 females, aged 26-66 years (mean age of 46). These patients were classified into two groups according to LAP after PTMC: 31 cases with LAP after PTMC of 12 mmHg or less (group A) and 20 cases with LAP after PTMC greater than 12 mmHg (group B). The patients of group A were younger (44 +/- 6 vs 48 +/- 6 years, p < 0.05), and had atrial fibrillation (af) less frequently (35 vs 65%, p < 0.05), and had mitral valve calcification less frequently (29 vs 65%, p < 0.01). Before PTMC, LAP (19 +/- 6 vs 23 +/- 5 mmHg, p < 0.01) was lower and mitral valve area (MVA) (0.95 +/- 0.24 vs 0.81 +/- 0.15 cm2, p < 0.05) larger in group A. Symptoms graded according to the New York Heart Association functional classification system were similar in both groups before PTMC. After the procedure, final MVA (1.79 +/- 0.69 vs 1.40 +/- 0.50 cm2, p < 0.05) was larger and systolic pulmonary artery pressure (32 +/- 9 vs 39 +/- 7 mmHg, p < 0.01) lower in group A. Mitral regurgitation > or = 3-grade tended to complicate more frequently (3 vs 20%, NS) in group B.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Evaluation of isokinetic hip strength after rotational acetabular osteotomy.

Fifty-four patients with dysplastic hip and secondary degenerative arthrosis (58 hips) underwent rotational acetabular osteotomy (RAO) using a conventional anterior-posterior method or a new technique involving detachment of the greater trochanter. Pre- and postoperative hip abductor strength (HAS) and knee extensor strength (KES) were evaluated using an isokinetic dynamometer. Postoperative HAS in patients treated by detachment of the greater trochanter reached preoperative levels 16 weeks postoperatively. Comparison of the postoperative HAS based on the two different surgical approaches showed that RAO by detachment of the greater trochanter was superior to the conventional method. Pre- and postoperative HAS showed a good correlation. Postoperative improvements in HAS over presurgical values were not significant in patients with advanced-stage arthrosis and severely dysplastic hips. Preoperative HAS should serve as an index for determining whether RAO is undertaken using detachment of the greater trochanter.

Acetabulum↗
PubMed1993

[Exposure to DMTP by sprayers and the urinary excretion of metabolites].

Exposure in vinyl hothouses to DMTP (0,0-dimethyl-s-(2-methoxy-1,3,4-thiadiazol-5(4H)-onyl-(4)-m ethyl)- dithiophosphate) was studied in 5 spray-operators and one assistant worker. To determine the level of exposure to DMTP, concentrations in the atmosphere, concentration in atmosphere near the operators breathing zone, skin levels from penetration through the operator's clothing, and urinary excretion of metabolites of DMTP (2,3-dihydro-5-methoxy-3-methyl-sulphonyl methyl-1,3,4-thiadiazol-2-one and 2,3-dihydro-5-methoxy-3-methyl-sulphinyl methyl-1,3,4-thiadiazol-2-one) were measured. The results were as follows; 1. DMTP concentrations in the atmosphere were 10.0-18.0 micrograms/m3, and concentrations in the atmosphere near the operators breathing zone were 5.4-33.6 micrograms/m3 during spraying. 2. Metabolites of DMTP were detected in all sprayers. Levels were 1.5 to 31.6 micrograms/day for the sulphonyl-metabolite. But it was not detected in the assistant sprayer. 3. Urinary concentrations of the DMTP metabolite were maximum 15-20 h after spraying. 4. Amount of DMTP adherent on the skin was estimated to be 0.4 to 71.3 micrograms for spray-operators. Variations resulted from differences in condition of protective clothing. 5. DMTP appeared to be absorbed not only through the respiratory system, but also through the skin.

Female↗
PubMed1993

[Prophylactic effect of methylprednisolone on cisplatin-induced nephrotoxicity in rats].

Cis-diamminedichloroplatinum (II) (cisplatin) is a very effective antitumor drug, but It has an adverse effect of nephrotoxicity. There are many reports concerning protective agents against cisplatin nephrotoxicity, but clinically useful modalities are very few. In the present study, prophylactic effects of methylprednisolone (MP) on cisplatin-induced nephrotoxicity were examined. Male Sprague-Dawley rats were injected iv with 6.5 mg/kg of cisplatin combined with a subcutaneous MP given sc in various doses at various timing. Rats were killed 5 days after cisplatin injection to determine BUN and serum creatinine levels. BUN and serum creatinine levels in rats pretreated with MP 4 or 2 hr before cisplatin injection were significantly lower than those in rats received cisplatin alone. Our preliminary results suggest that pretreatment with MP is an effective means of protection against cisplatin-induced nephrotoxicity.

Animals↗
PubMed1993

Proteases--structures, mechanism and inhibitors.

Proteases have been divided into four mechanistic classes: serine proteases, metalloproteases, aspartic proteases, and cysteine proteases. Once a new enzyme is classified by the use of general inhibitors, it is possible to design reactive inhibitors by using mechanistic information learned through study of other members of the same protease family. The most useful types of inhibitors for serine proteases are transition-state inhibitors including alpha-ketoesters and phosphonates, and mechanism-based inhibitors such as heterocyclic isocoumarin inhibitors. Some of these inhibitors are quite specific toward individual target serine proteases. Many proteases are involved in various disease states, and potent inhibitors of these enzymes have the potential to be developed as new therapeutic agents. In the future, it is likely than numberous specific protease inhibitors will be tested clinically for the treatment of human disease.

Amino Acid Sequence↗
PubMed1993

[Experimental study of liver regeneration and tumor growth following partial hepatectomy].

An experimental study was performed aiming to clarify the mechanism of early recurrence of hepatocellular carcinoma following hepatectomy. AH109A ascites hepatoma cells were implanted in a liver or subcutaneous tissue of male Donryu rats 5 days prior to 70% partial hepatectomy (H group) or simple laparotomy (L group) or non operation control (C group). Rats were sacrificed at 1, 3, 7 postoperative days. Tumor size, labelling index (LI), tissue blood flow (TBF) and regeneration rate of the remnant liver were measured. Tumor size of the remnant liver in hepatectomy group was 492 +/- 117 mm3 against 129 +/- 63 mm3 in laparotomy group showing enhancement of tumor growth following partial hepatectomy with statistical significance (p < 0.01). On the contrary, there was no difference in the growth of subcutaneous tumor among H, L, C group. A significant increase of LI in both liver and subcutaneous tumor cells comparable to regenerating liver cells at 24 hours after hepatectomy was observed in H group. It suggests that some humoral hepatotrophic factors increased DNA synthesis of not only tumor cells but liver cells. TBF in the tumor and remnant area of the liver were increased. This result supports that increased hepatotrophic factors and TBF led to the enhancement of tumor growth in the remnant liver following partial hepatectomy.

Animals↗
PubMed1993

[Composite resection of sciatic nerve for local recurrence of rectal cancer].

Three patients with local recurrence of rectal cancer involving the sciatic nerve underwent radical pelvic exenteration combined with sciatic nerve resection. This surgical procedure resulted in complete relief of intolerable cancer pain in all patients. After the rehabilitation, all could walk unassisted by wearing only a below-the-knee leg brace. The first patient died 16 months postoperatively due to multiple liver metastasis, but no local recurrence was documented. The second patient is alive 13 months postoperatively with bone and liver metastasis and pelvic wall recurrence. The third patient is alive 7 months postoperatively with no evidence of disease. Composite resection of lateral sciatic nerve improved the quality of life in patients who had local recurrence of rectal cancer with sciatic nerve involvement.

Adult↗
PubMed1993

[Evaluation of clinical usefulness of 99mTc-GSA, a functional hepatic imaging agent--correlation with per-rectal portal scintigraphy].

Liver scintigraphy using 99mTc-GSA, which binds specifically to the asialoglycoprotein receptors on the surface of the hepatocytes, was performed in 41 patients with chronic liver disease (11 chronic hepatitis cases and 30 liver cirrhosis) to investigate the correlations between the images and the various liver function tests. Two liver functional indexes, HH15 for plasma clearance of 99mTc-GSA and LHL15 for liver accumulation of 99mTc-GSA, showed significant differences between the chronic hepatitis group and the decompensated liver cirrhosis group. These indexes also showed significant correlations with the liver function tests such as serum albumin level and prothrombin time. HH15 and LHL15 correlated with the per-rectal portal shunt index obtained in 10 patients by 99mTcO4- per-rectal portal scintigraphy. These results suggest that HH15 and LHL15 have value as new liver functional indexes.

Adult↗