Biomedical subjects
Publications and source records attributed to Yuji Yamamoto.
A novel sugar-modified thymidine analogue, 3'-deoxy-4'-C-(2-hydroxyethyl)thymidine (X), was designed and synthesized to show that it can stabilize hairpin structures when it is present in the loop moiety, probably due to the flexibility of the one-carbon-elongated 4'-branched structure.
The impact of oxygen on a cell is strongly dependent on its metabolic state: survival in oxygen of free-living Lactococcus lactis, best known as a fermenting, acidifying bacterium, is generally poor. In contrast, if haem is present, L. lactis uses oxygen to switch from fermentation to respiration metabolism late in growth, resulting in spectacularly improved long-term survival. Oxygen is thus beneficial rather than detrimental for survival if haem is provided. We examined the effects of respiration on oxygen toxicity by comparing integrity of stationary phase cells after aerated growth without and with added haem. Aeration (no haem) growth caused considerable cellular protein and chromosomal DNA damage, increased spontaneous mutation frequencies and poor survival of recA mutants. These phenotypes were greatly diminished when haem was present, indicating that respiration constitutes an efficient barrier against oxidative stress. Using the green fluorescent protein as an indicator of intracellular oxidation state, we showed that aeration growth provokes significantly greater oxidation than respiration growth. Iron was identified as a main contributor to mortality and DNA degradation in aeration growth. Our results point to two features of respiration growth in lactococci that are responsible for maintaining low oxidative damage: One is a more reduced intracellular state, which is because of efficient oxygen elimination by respiration. The other is a higher pH resulting from the shift from acid-forming fermentation to respiration metabolism. These results have relevance to other bacteria whose respiration capacity depends on addition of exogenous haem.
Dpr is an iron-binding protein required for oxygen tolerance in Streptococcus mutans. We previously proposed that Dpr could confer oxygen tolerance to the bacterium by sequestering intracellular free iron ions that catalyze generation of highly toxic radicals (Y. Yamamoto, M. Higuchi, L. B. Poole, and Y. Kamio, J. Bacteriol. 182:3740-3747, 2000; Y. Yamamoto, L. B. Poole, R. R. Hantgan, and Y. Kamio, J. Bacteriol. 184:2931-2939, 2002). Here, we examined the intracellular free iron status of wild-type (WT) and dpr mutant strains of S. mutans, before and after exposure to air, by using electron spin resonance spectrometry. Under anaerobic conditions, free iron ion concentrations of WT and dpr strains were 225.9 +/- 2.6 and 333.0 +/- 61.3 microM, respectively. Exposure of WT cells to air for 1 h induced Dpr expression and reduced intracellular free iron ion concentrations to 22.5 +/- 5.3 microM; under these conditions, dpr mutant cells maintained intracellular iron concentration at 230.3 +/- 28.8 microM. A decrease in cell viability and genomic DNA degradation was observed in the dpr mutant exposed to air. These data indicate that regulation of the intracellular free iron pool by Dpr is required for oxygen tolerance in S. mutans.
BACKGROUND: Locations of femoral tunnels for anterior cruciate ligament replacement grafts remain a subject of debate. HYPOTHESIS: A lateral femoral tunnel placed at the insertion of the posterolateral bundle of the anterior cruciate ligament can restore knee function comparably to anatomical femoral tunnel placement. STUDY DESIGN: Controlled laboratory study. METHODS: Ten cadaveric knees were subjected to the following external loading conditions: (1) a 134-N anterior tibial load and (2) combined rotatory loads of 10-N.m valgus and 5-N.m internal tibial torques. Data on resulting knee kinematics and in situ force of the intact anterior cruciate ligament and anterior cruciate ligament graft were collected using a robotic/universal force-moment sensor testing system for (1) intact, (2) anterior cruciate ligament-deficient, (3) anatomical double-bundle reconstructed, and (4) laterally placed single-bundle reconstructed knees. RESULTS: In response to anterior tibial load, anterior tibial translation and in situ force in the graft were not significantly different between the 2 reconstructions except at high knee flexion. For example, at 90 degrees of knee flexion, anterior tibial translation was 6.1 +/- 2.3 mm for anatomical double-bundle reconstruction and 7.6 +/- 2.6 mm for laterally placed single-bundle reconstruction (P < .05). In response to rotatory loads, there were no significant differences between the 2 reconstruction procedures (4.8 +/- 2.4 mm vs 4.8 +/- 3.0 mm in anterior tibial translation at 15 degrees of knee flexion, P > .05). CONCLUSION: Lateral tunnel placement can restore rotatory and anterior knee stability similarly to an anatomical reconstruction when the knee is near extension. However, the same is not true when the knee is at high flexion angles. CLINICAL RELEVANCE: To reproduce the complex function of the anterior cruciate ligament, reproducing both bundles of the anterior cruciate ligament may be necessary.
The aim of this study was to evaluate the efficacy and toxicity of 5-fluorouracil (5-FU) and l-leucovorin (l-LV) given at the same dose intensity and administered monthly (given weekly for 3 weeks followed by a week of rest; arm A) or every 2 months (given weekly for 6 weeks followed by 2 weeks rest; arm B) to patients with advanced colorectal carcinoma. The dose of 5-FU was 500 mg/body or 750 mg/body, with an average dose of 432.8 mg/m2. A total of 7 institutions participated in this multi-center study and were randomly divided into 2 groups of arms A and B. Thirty-three patients were entered into arm A and 21 into B. The overall response rate was significantly (p = 0.007) greater in arm B (23.5%) than in arm A (0%). The most frequently observed toxicity was diarrhea, which was observed in 6.5% of arm A and in 33.3% of arm B, marking a significant difference (p = 0.034). These data suggest that a monthly 5-FU/l-LV regimen might be less toxic than a 2-months regimen and less effective at the dose given as above. Further study is needed to evaluate the efficacy of a monthly regimen.
We report a case of intracranial adenoid cystic carcinoma in the middle cranial fossa. A 40-year-old woman had noticed a tumor in the left external auditory canal 8 years previously. It was totally resected at that time. Histologically, the tumor was diagnosed as an adenoid cystic carcinoma. Recently the patient presented with loss of consciousness, suffering from mild recent-memory disturbance. Neurological examination revealed no other abnormalities. Magnetic resonance imaging (MRI) demonstrated an enhanced solid mass with a multicystic component in the left temporal lobe. She underwent subtotal removal of the tumor. It was well-demarcated, and was confirmed to be adhesive to the dura matter of the middle cranial fossa. Histology of the tumor was the same as it was 8 years ago. She was discharged from our hospital without neurological deficits. Two months after surgery, gamma knife radiosurgery was performed against the residual tumor.
The clinical impact of survivin on human cancer pathogenesis and prognosis has been investigated. To clarify the clinical effect of survivin on tumor behavior and prognosis of patients with hepatocellular carcinoma (HCC), the expression of survivin mRNA in 40 samples of HCC tissue and matched-adjacent liver tissue, as well as 7 healthy hepatic tissue samples were measured by a real-time reverse transcription polymerase chain reaction. The expressed level of survivin mRNA (log copies/microg total RNA) in healthy liver tissue was 1.95+/-0.44, in morbid liver tissue adjacent to the tumors was 4.79+/-0.96, and in HCC tissue was 5.87+/-0.73 (values are mean +/- SD and P<0.001). The amount of survivin mRNA in HCC tissues correlated negatively with the apoptotic indices (r=-0.573 and P<0.001) and correlated positively with the proliferation indices (r=0.433 and P=0.005). Expression of survivin was significantly related with histologic grade (P=0.011) and pathological tumor stage (P=0.017). Patients with HCC tumors that had a large amount of survivin mRNA (> or = mean) had lower survival rate (P=0.030), but multivariate analysis showed only Ki-67 labeling index, histologic grade, and pathologic T stage to be the independent prognosticators. These findings indicate that survivin is associated with reduced tumor cell apoptosis, increased tumor cell proliferation, and histologically aggressive tumor features, and may play an important role in tumor progression of HCC. However, further examination is needed to clarify its predictive significance for HCC patients.
We report a case of sudden unexpected death due to rupture of the stomach. A 49-year-old man was found dead in a public lavatory. Autopsy findings revealed two rupture wounds measuring 14 cm and 6 cm located in the fundus of stomach at the side of the greater curvature despite of any superficial injury. The deceased had an ulcer in the lesser curvature of stomach, and dilation in this area was expected to be impaired. Under this condition, excessive over-eating resulting in over-extension of the stomach wall at the greater curvature was speculated to have caused stomach rupture.
This study was performed to clarify how dietary fiber (DF) with different viscosities would be associated with dietary RNA metabolism. Male Wistar strain rats, four weeks old, were fed diets containing a 3% (w/w) yeast RNA and a 5% (w/w) viscous DF for five days. Viscosity of DF samples used, in order of strength, were xanthan gum (XG) > guar gum (GG) > locust bean gum (LBG) > karaya gum (KG) > pectin (PE) = arabic gum (AG) > CM-cellulose (CMC) = inulin (IN). The serum uric acid concentration in the viscous DF groups significantly decreased as compared with that in the cellulose (CL) group. The urinary excretions of uric acid and allantoin in the respective groups given AG, GG, IN, KG, PE, and XG were significantly suppressed as compared with those in the CL group. The fecal RNA excretion was markedly increased in the IN, KG, PE, and XG groups in comparison to the CL group. The DF with high viscosity significantly suppressed RNA digestion by RNase A and decreased uptakes of 14C-labeled adenosine and adenosine 5'-monophosphate (5'-AMP) in rat jejunum. The results reveal that the suppressive effect of DF on elevation of serum uric acid concentration induced by dietary RNA in rats is associated with the strength of DF viscosity. The mechanism by which this is accomplished is suggested to be attributed to the inhibitions of digestion for dietary RNA and/or absorption of the hydrolyzed compounds.
BACKGROUND: Calcification of the media of arteries is common in patients with end-stage renal disease (ESRD) undergoing haemodialysis and is a major cause of arteriosclerosis. The aim of this study was to clarify the role of glycoxidative modification of elastin in the calcification of aortic media in this group of patients. METHODS: Samples of tunica media were obtained from non-atherosclerotic areas of the aortas of cadavers of seven non-diabetic patients with ESRD (age 65.5 +/- 10.6 years) and 10 age-matched controls (age 61.1 +/- 10.3 years). The localization of pentosidine, a major glycoxidation product, and calcium deposits in the media were examined using immunohistochemical and von Kossa staining, followed by orcein staining for elastin fibres. Tissue levels of pentosidine and calcium were measured in elastase-digested media using reversed high-performance liquid chromatography and atomic absorption spectrophotometry, respectively. RESULTS: In aortic media, but not intima, immunostained pentosidine was observed along elastin fibres or in the extracellular spaces between them. Early calcification was manifest as small punctate calcified deposits along elastin fibres in the media. Advanced calcification was found as large, confluent calcified deposits in extracellular spaces between elastin fibres. Double staining showed co-localization of pentosidine and calcified deposits in the media. Both the staining density of pentosidine and calcification were more prominent in ESRD patients than in controls. The mean medial contents of both elastin-associated pentosidine and calcium were significantly higher in ESRD patients than in controls. In ESRD patients, the level of calcium in elastase-digested media correlated significantly with pentosidine levels, which increased in parallel with the duration of haemodialysis. CONCLUSIONS: Our results indicate that glycoxidative modification of elastin in aortic media may be involved in the enhancement of medial calcification in ESRD patients on haemodialysis.
We investigated whether a plant chitinase can be used as a biocontrol agent instead of chemical fungicides by spraying chitinase E (family 19; class IV) from a yam (Dioscorea opposita Thunb) alone or together with beta-1,3-glucanase directly onto the surface of a powdery mildew infecting strawberry berries and leaves. Results were observed by eye and with a scanning electron microscope. The powdery mildew infecting the strawberries was degraded, mainly by the chitinase, and the disease did not appear again for more than 2 weeks. These results indicated that this kind of plant chitinase might be safe and biodegradable biocontrol agent for use instead of conventional fungicides.
In this study we used paraffin-embedded human pituitary obtained from 248 autopsy cases and identified mixed cell follicles by the immunohistochemical method. We examined the number and size of the mixed cell follicles, and the ratio of each component cell of these follicles, in the anterior pituitary at various age groups. The number of follicles increased with age, and the size of the follicles also tended to enlarge with age. Statistical analysis showed that a high correlation existed between age and the number or the size of the mixed cell-follicles formed by various adenohypophyseal cells. In addition, when the proportions of the different cell types that formed the follicles were examined, sex differences were observed with aging for the GH cells, the PRL cells, and the gonadotroph (GTH) cells, while no changes were observed with aging in both men and women for the ACTH cells and TSH cells. These results indicate that the number, size, and ratio of each component cell of follicles in the anterior pituitary are adequately applicable for the purpose of age estimation in routine forensic medicine.
Allele and genotype frequencies for 15 short tandem repeat (STR) polymorphisms--D3S1358, TH01, D21S11, D18S51, Penta E, D5S818, D13S317, D7S820, D16S539, CSF1PO, Penta D, vWA, D8S1179, TPOX and FGA--in a Japanese population were estimated. No deviations of the observed allele frequency from Hardy-Weinberg equilibrium expectations were found for any of the systems studied. Between 2 new pentanucleotide STR loci, Penta E and Penta D, for which there is only limited data regarding the allelic distribution in Japanese, the Penta E locus was found to be highly polymorphic and exhibited a tri- or tetra-modal distribution pattern having allelic peaks with 5, 11, 15 and 20 repeats. The distribution was significantly different from that of the other ethnic groups. Statistical parameters of forensic importance, the power of discrimination (PD), observed and expected heterozygosity values (H), polymorphism information content (PIC), power of discrimination (PD), matching probability (pM), power of exclusion (PE), and typical paternity index (PI), were calculated for the loci. These parameters indicated the usefulness of the loci in forensic personal identification and paternity testing among Japanese. The systems Penta E, FGA, D18S51 and D8S1179 were the most informative. This method was successfully applied to forensic personal identification and paternity testing among Japanese, thereby confirming its efficacy for forensic practice.
We report the effects and toxicities of intravenous administration of cisplatin, 5-FU and high-dose leucovorin for advanced esophageal cancer. Eight patients were registered and sixteen lesions were measurable. Of these sixteen lesions, thirteen were primary or synchronous metastatic lesions, and the response was 69%. Three were recurrence lesions, and the response rate for them was 0%. Including seven neoadjuvant cases, ten patients had oral mucositis, and seven patients had appetite loss. Other toxicities were diarrhea, myelosuppression, renal dysfunction, and alopecia. All were reversible after administration. It is suggested that this treatment regimen is a superior neoadjuvant chemotherapy with low toxicity.
The natural history of asymptomatic unruptured aneurysms that have not been subjected to surgery was studied radiologically using MRA and MRI and 3D-CT angiography (3D-CTA) commencing in 1993. We report on the growth of documented asymptomatic unruptured aneurysms in three patients. Growth of the aneurysms was followed by repeated MRA, MRI and 3D-CTA. In Case 1, a 71-year-old woman had been diagnosed as having a 3 mm unruptured anterior communicating artery aneurysm. The size of the aneurysm had expanded to 4 mm, 2 years later. This was detected during a follow-up MRA and confirmed by angiography. After this follow-up MRA, the aneurysm showed no change in size or shape for 8 years. Case 2 was that of a 75-year-old woman who had a 4.5 mm aneurysm involving the basilar artery and the superior cerebellar artery. 12 months later, an MRA was carried out as a follow-up study. This MRA revealed that the aneurysm had developed a bleb and was expanding. 8 months later the patient bled from the aneurysm and underwent surgery, but died. Before surgery, the diameter of the aneurysm, confirmed by angiogram, was 5.5 mm including the bleb. The third patient was a 66-year-old woman who had a 7 mm internal aneurysm involving the carotid artery and the posterior communicating artery. 3 years later a 3D-CTA detected the expansion of the aneurysm and development of an aneurysm bleb. 6 years later more expansion occurred and 3 months after that the patient bled from the aneurysm and underwent clipping. At that time, the diameter of the aneurysm, confirmed by angiography, was 13 mm including the bleb. In this follow-up study, patients with diagnosed asymptomatic unruptured aneurysms were followed up by MRA and MRI and 3D-CTA to determine risk factors for aneurysm rupture. We emphasize the fact that growth of an unruptured aneurysm and formation of blebs are important risk factors of aneurysm rupture.
We report a case of small cell carcinoma of the stomach in a 60-year-old man. The patient was found to have a gastric tumor by routine upper gastrointestinal endoscopy for chronic gastrititis, and was admitted to the hospital. The patient underwent a curative distal gastrectomy with D2 lymph node dissection following a diagnosis of early gastric cancer at the posterior wall of the antrum, in June 2001. Surgical findings were T1, N1, P0, H0, M0, stage I b. The final pathological diagnosis was small cell carcinoma of the stomach with severe lymphatic and vascular invasion (INF alpha, sm, ly3 v2, n1 (+)). In a review of 47 cases seen in the Japanese literature, only 5 patients had early gastric cancer. Lymph node metastasis was observed in 95.0% of all cases, and liver metastasis in 41.0%. Four of the 5 patients with early gastric cancer (80.0%) had lymph node metastases. The prognosis was reported to be extremely poor because small cell carcinoma frequently metastasizes to lymph nodes and/or the liver even in an early stage. The chemotherapy selected by many hospitals is mainly CDDP, but the use of chemotherapeutic drugs varied from hospital to hospital and no effective chemotherapy for the disease has been established as yet.
In the process of angiogenesis, endothelial adhesion molecules play a significant role in vascular morphogenesis, in coordination with angiogenic factor signaling. Here we report that a novel angiogenesis inhibitor, E7820 (an aromatic sulfonamide derivative), inhibited in vitro proliferation and tube formation of human umbilical vascular endothelial cell (HUVEC). E7820 decreased integrin alpha2, 3, 5, and beta1 in confluent culture of HUVEC, and integrin alpha2 was initially suppressed in mRNA level, followed by decrement of integrins alpha3, 5, and beta1. The inhibition of integrin alpha2 expression in HUVEC showed dose dependence but did not alter the level of CD31. Up-regulation of integrin alpha2 by phorbol 12-myristate 13-acetate abrogated the inhibitory effect of E7820 on tube formation within type I collagen gel, whereas addition of antibody against integrin alpha2 canceled the phorbol 12-myristate 13-acetate effect. These results suggest that E7820 inhibited tube formation through the suppression of integrin alpha2. Oral administration of E7820 remarkably resulted in inhibition of tumor-induced angiogenesis in mouse dorsal air sac model, and tumor growth of human colorectal tumor cell lines (WiDr and LoVo) was inhibited in xenotransplanted model in mice. This is the first time that a small molecule has been shown to modulate integrins, and this finding may provide the basis for a new approach to antiangiogenic therapy through the suppression of integrin alpha2 on endothelium.
STUDY DESIGN: A biochemical and histochemical study investigating the role of CTGF/Hcs24 in the ossification of the posterior longitudinal ligament (OPLL) was conducted. OBJECTIVE: To clarify the involvement of CTGF/Hcs24 in ectopic bone formation in OPLL through endochondral ossification using human tissue. SUMMARY OF BACKGROUND DATA: Previous studies have shown that various cytokines are involved in the occurrence or development of ectopic bone formation in OPLL. Recently, the authors cloned an mRNA predominantly expressed in chondrocytes by differential display PCR and found that its gene, hcs24, is identical to that of connective tissue growth factor. It has been shown that CTGF/Hcs24 plays a major role in endochondral ossification. METHODS: Ossified ligament tissues were taken from seven male OPLL patients during surgery. Immunohistochemical staining was performed using an antibody specific for CTGF/Hcs24. Spinal ligament cells were isolated from five OPLL patients as well as five non-OPLL patients. The cells were incubated with recombinant human CTGF/Hcs24 or TGFbeta. The expression of ALP was analyzed by RT-PCR. For the effects of TGFbeta, the expression of CTGF/Hcs24 mRNA was analyzed. RESULTS: Immunohistochemical staining showed that chondrocytes in the transitional region from nonossified to ossified ligament were stained with an antibody against CTGF/Hcs24. It was found that CTGF/Hcs24 enhanced the expression ALP mRNA in OPLL cells, whereas the expression remained unchanged in non-OPLL cells. The expression of CTGF/Hcs24 mRNA in OPLL and non-OPLL cell lines was increased by TGFbeta, and there was no significant difference between the two groups. However, TGFbeta and CTGF/Hcs24 enhanced the expression of ALP mRNA only in OPLL cells. CONCLUSIONS: According to the study results, CTGF/Hcs24 may not only be an important factor in the development of endochondral ossification in OPLL, but may also be responsible for initiating osteogenesis in spinal ligament cells.