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Biomedical subjects

H Yano

Publications and source records attributed to H Yano.

At least 73 records · Page 4Linked to original sources
PubMed2001

Plasmid-encoded metallo-beta-lactamase (IMP-6) conferring resistance to carbapenems, especially meropenem.

In 1996, Serratia marcescens KU3838 was isolated from the urine of a patient with a urinary tract infection at a hospital in northern Japan and was found to contain the plasmid pKU501. Previously, we determined that pKU501 carries bla(IMP) and the genes for TEM-1-type beta-lactamases as well as producing both types of beta-lactamases (H. Yano, A. Kuga, K. Irinoda, R. Okamoto, T. Kobayashi, and M. Inoue, J. Antibiot. 52:1135-1139, 1999). pKU502 is a recombinant plasmid that contains a 1.5-kb DNA fragment, including the metallo-beta-lactamase gene, and is obtained by PCR amplification of pKU501. The sequence of the metallo-beta-lactamase gene in pKU502 was determined and revealed that this metallo-beta-lactamase gene differed from the gene encoding IMP-1 by one point mutation, leading to one amino acid substitution: 640-A in the base sequence of the IMP-1 gene was replaced by G, and Ser-196 was replaced by Gly in the mature enzyme. This enzyme was designated IMP-6. The strains that produced IMP-6 were resistant to carbapenems. The MICs of panipenem and especially meropenem were higher than the MIC of imipenem for these strains. The k(cat)/K(m) value of IMP-6 was about sevenfold higher against meropenem than against imipenem, although the MIC of meropenem for KU1917, which produced IMP-1, was lower than that of imipenem, and the MIC of panipenem was equal to that of imipenem. These results support the hypothesis that IMP-6 has extended substrate profiles against carbapenems. However, the activity of IMP-6 was very low against penicillin G and piperacillin. These results suggest that IMP-6 acquired high activity against carbapenems, especially meropenem, via the point mutation but in the process lost activity against penicillins. Although IMP-6 has reduced activity against penicillins due to this point mutation, pKU501 confers resistance to a variety of antimicrobial agents because it also produces TEM-1-type enzyme.

Amino Acid Sequence↗
PubMed2001

Overproduction of L-Lysine from methanol by Methylobacillus glycogenes derivatives carrying a plasmid with a mutated dapA gene.

The dapA gene, encoding dihydrodipicolinate synthase (DDPS) partially desensitized to inhibition by L-lysine, was cloned from an L-threonine- and L-lysine-coproducing mutant of the obligate methylotroph Methylobacillus glycogenes DHL122 by complementation of the nutritional requirement of an Escherichia coli dapA mutant. Introduction of the dapA gene into DHL122 and AL119, which is the parent of DHL122 and an L-threonine producing mutant, elevated the specific activity of DDPS 20-fold and L-lysine production 2- to 3-fold with concomitant reduction of L-threonine in test tube cultures. AL119 containing the dapA gene produced 8 g of L-lysine per liter in a 5-liter jar fermentor from methanol as a substrate. Analysis of the nucleotide sequence of the dapA gene shows that it encodes a peptide with an M(r) of 30,664 and that the encoded amino acid sequence is extensively homologous to those of other organisms. In order to study the mutation that occurred in DHL122, the dapA genes of the wild type and AL119 were cloned and sequenced. Comparison of the nucleotide sequences of the dapA genes revealed that the amino acid at residue 88 was F in DHL122 whereas it was L in the wild type and AL119, suggesting that this amino acid alteration that occurred in DHL122 caused the partial desensitization of DDPS to the inhibition by L-lysine. The similarity in the amino acid sequences of DDPS in M. glycogenes and other organisms suggests that the mutation of the dapA gene in DHL122 is located in the region concerned with interaction of the allosteric effector, L-lysine.

Amino Acid Sequence↗
PubMed2001

Assessment of segmental wall motion abnormalities using contrast two-dimensional echocardiography in awake mice.

Murine models of cardiac disease are becoming an important tool for studying pathophysiological processes. Development of methods to accurately assess ventricular function are therefore important. The purpose of this study was to evaluate the feasibility of echocardiographic assessment of segmental wall motion abnormalities in a murine model of myocardial infarction. Two-dimensional contrast (C+) and noncontrast (C-) echocardiography were performed in 76 awake mice 2 days before and 2 days after left coronary ligation. The short-axis images obtained with two-dimensional echocardiography and corresponding postmortem cross-sectional histological samples stained with Evans blue dye were each divided into 16 segments, and all matched segments were examined for correlation between wall motion abnormalities and myocardial hypoperfusion. With the use of contrast enhancement, the number of visualized segments was significantly increased (base: C- 86%, C+ 98%; midpapillary: C- 57%, C+ 89%; apex: C- 30%, C+ 74%). Agreement between echocardiographically assessed regional wall motion abnormalities and pathologically determined hypoperfusion in basal, midpapillary, and apical levels were 90%, 93%, and 93%, respectively. Agreement between echocardiographically normal wall motion and pathologically normal findings in basal, midpapillary, and apical levels were 99%, 88%, and 71%, respectively. Thus echocardiographic assessment of segmental wall motion in awake mice was feasible and the accuracy was improved with the use of a contrast agent.

Animals↗
PubMed2001

Anesthetic inhibition in ischemic and nonischemic murine heart: comparison with conscious echocardiographic approach.

It is well known that the level of anesthesia obtained by intraperitoneal injection is variable and may alter cardiac function. In this study, we compared the effects of different anesthetics on cardiac function with the conscious state using high-resolution two-dimensional echocardiography in nonischemic and ischemic mice. Eighty-four mice were tested before and after surgery with ligation of the coronary artery. All 84 mice were studied in the conscious state and under high-dose intraperitoneal anesthesia. Twenty-two of 84 mice were studied under low-dose intraperitoneal anesthesia. Another 22 mice were also studied under gas anesthesia and spontaneous breathing. Experiments in the conscious state were performed by two investigators before the administration of anesthesia: one investigator held the animal and the transducer and the other operated the ultrasound equipment. Left ventricular systolic function was measured, and measurements obtained after surgery were compared with infarcted areas assessed by histological staining. Results showed that both high- and low-dose intraperitoneal anesthesia significantly reduced heart rates and left ventricular contractility in both pre- and postsurgical mice as opposed to conscious mice (P < 0.01). There were significantly higher correlation coefficients between mean fractional area change (FAC) and infarcted area in conscious state compared with high-dose intraperitoneal anesthesia (P < 0.05). The correlation coefficient between FAC and infarcted area during gas anesthesia was also significantly higher compared with high-dose intraperitoneal anesthesia (P < 0.05). In conclusion, conscious experiments or the use of gas anesthesia is preferred for echocardiographic assessment of cardiac function in mice because intraperitoneal injection significantly induces a significant reduction in heart rate and left ventricular systolic function.

Anesthetics, Inhalation↗
PubMed2001

Assessment of left ventricular systolic function using contrast two-dimensional echocardiography with a high-frequency transducer in the awake murine model of myocardial infarction.

The estimation of global left ventricular function using M-mode echocardiography has technical limitations in the murine model of myocardial infarction (MI), but the recent improvements in 2-dimensional (2-D) echocardiography using a high-frequency transducer provide more accessible images. Furthermore, intravenous injection of contrast agent has the additional benefit of enhancing the endocardial border in the murine heart. The present study was designed to evaluate the value of 2-D echocardiography with intravenous injection of contrast agent in the assessment of global systolic function of the murine heart with MI. Two-dimensional and M-mode echocardiography without and with intravenous injection of contrast agent (Optison, 0.1-0.15 ml) were performed in 76 awake mice 2 days before and 2 days after left coronary artery ligation. Fractional shortening (FS) was calculated from the end-diastolic and end-systolic diameters on M-mode echocardiography, and fractional area change (FAC) from the end-diastolic and end-systolic areas on 2-D echocardiography. Both FS and FAC were compared with the areas of hypoperfusion observed in the pathological samples. The use of contrast agent improved the number of hearts that could be evaluated by both the M-mode and 2-D method (M-mode: non-contrast 87% vs contrast 99%, p<0.01; 2-D: non-contrast 26% vs contrast 89%, p<0.001). FAC from the 2-D method correlated better with the region of hypoperfusion in the pathological samples than did FS from the M-mode method (FAC: r=0.84 vs FS: r=0.51). In conclusion, FAC obtained from 2-D contrast echocardiography is useful for noninvasive assessment of global systolic function in infarcted murine hearts and can be used to serially assess systolic function in various models of the murine heart.

Albumins↗
PubMed2001

Expression and function of interleukin-8 in human hepatocellular carcinoma.

Expression and functions of interleukin (IL)-8, a pro-inflammatory cytokine with angiogenesis action, was examined in 23 surgically resected hepatocellular carcinoma (HCC) specimens and 7 HCC cell lines. In all HCC tissues, IL-8 expression was confirmed with reverse-transcription polymerase chain reaction method and enzyme-linked immunosorbent assay, and immunohistochemistry showed HCC cells were the major producer of IL-8 in the tissues. Microvessel density was measured by the double immunohistochemical staining of muscular vessels in HCC tissues, but the density was not related to the level of IL-8 in the HCC tissues. On the other hand, in the co-culture of human umbilical vein endothelial cells (HUVEC) and a HCC cell line (KIM-1), IL-8 produced by KIM-1 significantly accelerated the proliferation of HUVEC. In addition, cases with a high IL-8 level in cancerous tissue had a significantly higher frequency of portal vein invasion, venous invasion and bile duct invasion (p<0.05). In the cultures of 7 HCC cell lines IL-8 secretion into culture medium increased with the treatment of IL-1beta or tumor necrosis factor-alpha. This showed IL-8 expression is regulated by inflammatory cytokines. IL-8 produced by HCC is an angiogenesis factor of HCC, but it could have a much more important role in the invasion and metastasis of HCC.

Aged↗
PubMed2001

[Evaluation for factors associated to early tracheal extubation after coronary artery bypass grafting].

Recent studies suggest that early tracheal extubation after coronary artery bypass grafting (CABG) may reduce intensive care unit use and cost. During recent two years, 96 patients were underwent CABG under cardiopulmonary bypass by low-dose fentanyl and isoflurane anesthesia. We compared two groups of patients for evaluation of factors associated to early tracheal extubation. 47 cases (Group A) were extubated within six hours (average 4.4 hrs) following operation, and 26 cases (Group B) were extubated later than twelve hours (average 57.5 hrs). It is suggested that emergency cases, female, elderly patients, dysfunction of kidney and long operation time associated to late extubation. But early extubation after CABG does not increase perioperative morbidity except for the cases that fell in low cardiac output syndrome or postoperative respiratory complications.

Adult↗
PubMed2001

[Evaluation of chemosensitivity testing by CD-DST, and TS and DPD activity in cases of colorectal liver].

We evaluated the usefulness of the following three in vitro assays in cases of resected colorectal liver metastases. Chemosensitivity by collagen gel droplet drug sensitivity test (CD-DST) was very low in all cases, suggesting this method is not predictive for this disease. In contrast, thymidylate synthetase (TS) activity and dihydropyrimidine dehydrogenase (DPD) activity in tumor tissue were high in many patients with recurrent disease. Thus, these enzyme activities are promising for assessment of clinical outcome following hepatic resection of colorectal liver metastases. Further analyses with large numbers of cases are needed to determine the significance of these in vitro studies.

Colorectal Neoplasms↗
PubMed2001

[Significant role of cisplatin and 5-FU combination chemotherapy for first-line intensive treatment for advanced esophageal cancer].

We evaluated the efficacy of first-line chemotherapy consisting of cisplatin and 5-fluorouracil combination therapy (in the following, FP) in intensive treatment for esophageal cancer. This first-line chemotherapy was administered to 18 patients with squamous cell carcinoma. Three patients had T2 tumor, 10 had T3 and 5 had T4. Lymph node metastasis was detected in 10 patients and not detected in 8 patients. Five patients had distant metastasis. Ten patients showed a partial response and the response rate was 55.6%. Of these 10 patients, 5 were followed with surgery, 3 of whom survived without recurrence of the disease. Five patients were treated by FP, radiation therapy or combination of FP and radiation. Of these 5 patients, 2 showed a complete response. On the other hand, 8 nonresponders died from progressive disease, despite following intensive treatment. These results suggest that first-line chemotherapy by FP, which requires following intensive treatment, improves the overall long-term survival of advanced esophageal cancer patient.

Aged↗
PubMed2001

[Usefulness of hepatic arterial infusion chemotherapy for liver metastasis in gastric cancer].

UNLABELLED: We have performed intra-hepatic arterial chemotherapy for 9 patients with liver metastasis arising from gastric cancer. We mainly used 5-FU and CDDP as antineoplastic drugs. RESULTS: The median survival after gastrectomy was 600 days. Of 9 cases, 2 showed CR, 4 PR, 2 NC, 1 PD. The response rate was 67%. The 9 cases were classified into 2 groups. One group, the short-term survival group, concised of 5 patients that had no more than 2 years survival and the other, the long-term survival group, consisted 4 patients that had more than 2 years survival. We compared these 2 groups and found no difference in the primary lesions between the 2 groups. The patients in the long-term survival group had fewer and smaller metastatic lesions in the liver than the patients of the short-term survival group. The patients in the long-term survival group had no unresectable lesions except liver metastasis when gastrectomy was performed. However, 2 patients in the short term survival group had unresectable lymphatic involvement at the time gastrectomy was performed. Of 9 patients, 6 died from the extrahepatic lesion. CONCLUSION: The intra-arterial chemotherapy was effective and useful for liver metastasis arising from gastric cancer. However, the majority of patients died from extrahepatic lesions. We should therefore consider the use of systemic chemotherapy with intra-arterial chemotherapy.

Aged↗
PubMed2001

[Surgical treatment of coronary artery-pulmonary artery fistula with coronary aneurysm].

We experienced 4 cases of coronary artery-pulmonary artery fistula with coronary aneurysm, three patients had symptoms of chest pain, and 1 patient had cardiac murmur. Coronary arteriography showed that three patients had fistulas from the left coronary artery to the pulmonary artery; and that 1 patient had a fistula from both the right and left coronary arteries to the pulmonary artery. Moreover, 1 patient had 90% diameter stenosis of segment 7. The maximum diameter of the coronary aneurysm ranged from 12 to 20 mm (average: 15.3 mm). One patient underwent closure of the opening of the fistula, 2 patients underwent multiple ligatures of fistulas, and 1 patient underwent multiple ligatures of fistulas with coronary artery bypass grafting. The postoperative course of every patient was uneventful. There have been 42 reports on this abnormality in Japan. We should treat the fistula as early as possible to prevent cardiac complications such as myocardial ischemia and rupture of coronary aneurysm.

Adult↗
PubMed2001

Lipid extracted freeze-dried bank bone sterilized with low temperature plasma.

Ethylene oxide gas (EOG) is widely used for sterilization of freeze-dried bone. Recently EOG is regulated for clinical use because of cytotoxicity and environmental pollution concerns. Low Temperature Plasma Sterilization (LTPS) has no toxicity and mutagenicity working with a hydrogen peroxide gas plasma at 45 degrees centigrade. We have now used this method experimentally and clinically to sterilize freeze-dried bone. Cortical bone with a thickness of 5 mm and cancellous bone with a 10 mm cubic size were prepared, washed, defatted, dehydrated by freeze drying and finally sterilized by LTPS. As a Microbiological test, defatted freeze-dried bone was contaminated with B. subtilis, and after then the contaminated bone was treated with LTPS and the bacteria was proven inactive. Mechanical testing on rabbit cortical bone was investigated by compression testing using a mechanical testing machine. No differences between EOG treated and LTPS treated bone were found. From December 1996, 52 patients who had small and middle bone defects were treated with defatted, freeze-dried and LTPS sterilized bone. Clinical result was good. No deep infections, no transmission of virus infections or severe graft absorption were noted. The LTPS bank bone is safe and useful to reconstruction to small bone defects.

Bone Banks↗
PubMed2001

Effect of long-term bedrest on lower leg muscle activation patterns during quiet standing.

It has been well known that balance instabilities after long-term exposure to microgravity (e.g., Anderson et al. 1986) or bedrest (BR) can be related to alterations and/or adaptations to postural control strategies. Little is known, however, how the reduced muscular activity affects the activation pattern of the lower limb muscles during quiet standing (QS). The purpose of this study was to investigate whether or not any changes in the lower limb muscle activation patterns during QS would occur after BR.

Adult↗
PubMed2001

Reflex response changes during hyper and microgravity.

This paper reports the quantitative evaluation of the H-reflex exhibited by parabolic flight with exposure to micro and high-gravity. With respect to previous findings in parabolic flights and short-term space missions, the analysis focused on reflex activity in weightlessness. The aim of this study was to investigate the effect of gravity on H-reflex and motor evoked potentials (MEP) in soleus muscle (SOL) during parabolic flight.

Adult↗
PubMed2000

The Na+-driven Cl-/HCO3- exchanger. Cloning, tissue distribution, and functional characterization.

The Na(+)-driven Cl(-)/HCO(3)(-) exchanger is an important regulator of intracellular pH in various cells, but its molecular basis has not been determined. We show here the primary structure, tissue distribution, and functional characterization of Na(+)-driven chloride/bicarbonate exchanger (designated NCBE) cloned from the insulin-secreting cell line MIN6 cDNA library. The NCBE protein consists of 1088 amino acids having 74, 72, and 55% amino acid identity to the human skeletal muscle, rat smooth muscle, and human kidney sodium bicarbonate cotransporter, respectively. The protein has 10 putative membrane-spanning regions. NCBE mRNA is expressed at high levels in the brain and the mouse insulinoma cell line MIN6 and at low levels in the pituitary, testis, kidney, and ileum. Functional analyses of the NCBE protein expressed in Xenopus laevis oocytes and HEK293 cells demonstrate that it transports extracellular Na(+) and HCO(3)(-) into cells in exchange for intracellular Cl(-) and H(+), thus raising the intracellular pH. Thus, we conclude that NCBE is a Na(+)-driven Cl(-)/HCO(3)(-) exchanger that regulates intracellular pH in native cells.

Animals↗
PubMed2000

K-ras point mutation is associated with enhancement by deoxycholic acid of colon carcinogenesis induced by azoxymethane, but not with its attenuation by all-trans-retinoic acid.

The effects of deoxycholic acid (DCA) with and without all-trans-retinoic acid (ATRA) on the incidence of colon tumors induced by azoxymethane, the incidence of K-ras point mutation in colon tumors and the labeling index of colon mucosa were investigated in male Wistar rats. Rats received 5 weekly injections of 7.4 mg/kg body weight of azoxymethane. From the start of the experiment, all rats in 3 groups also received chow pellets containing 0.3% DCA with and without s.c. injections of 0.75 or 1.5 mg/kg body weight of ATRA every other day until the end of week 45. Oral administration of DCA significantly increased the incidence of colon tumors in week 45. Concomitant use of DCA and ATRA at either dose significantly attenuated the enhancement by DCA of colon tumorigenesis. Administration of DCA significantly increased the incidence of K-ras point mutation in colon tumors and the labeling index in the colon mucosa. Combined administration of DCA and ATRA significantly reduced the labeling index of colon mucosa, which was increased by DCA, but did not affect the incidence of K-ras point mutation in colon tumors. These findings suggest that DCA enhances development of colon tumors and that this enhancement is attenuated by ATRA. A possible mechanism of this enhancement is induction of K-ras point mutation. However, decreased cell proliferation in the colon mucosa may be closely related to the attenuation of DCA-enhanced colon tumorigenesis, but not suppression of K-ras point mutation.

Administration, Oral↗