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Biomedical subjects

Y Imai

Publications and source records attributed to Y Imai.

At least 505 records · Page 28Linked to original sources

[Experimental study on resuscitation and salvage of myocardial function (RSMF) after normothermic ischemic arrest].

We studied in anesthetized dogs, the effects of cardiopulmonary bypass with normothermic blood, crossclamping of the aortic root, and continuous warm blood cardioplegia as a part of circulatory support on the ability of the recovery of the deteriorated myocardial function, and compared this method with the circulatory support under empty beating stage. Eleven dogs were subjected to the deteriorated myocardial function by 30 minute normothermic ischemic arrest and myocardial function was measured (baseline function). In 5 dogs (Group A), coronary perfusion of 5 ml/kg/min with normothermic blood was established under empty beating state. In other 6 dogs (Group B), the aorta was then clamped and 30 minute infusion of warm blood contained 15 mEq/l of potassium and 2 mEq/l of Magnesium was given by 2.5 ml/kg/min as a part of circulatory support. After this, aortic clamp was released and coronary perfusion of 5 ml/kg/min with normal warm blood followed under empty beating state. Cardiac function was measured at the periods of 40, 60 and 90 minutes of circulatory support and compared between the two groups. The parameters of left ventricular function (developed pressure, dp/dt, -dp/dt) were deteriorated by 30 minutes ischemia by about 50% compared with baseline function. In Group a, they improved gradually along with the duration of circulatory support and 90 minutes were required to return to the baseline function. In Group B, however, their % recovery reached 100% at the period of 40 minutes and maintained over 100% thereafter. RSMF could recover myocardial function from ischemic damage more quickly and effectively compared with circulatory support under empty beating state.

Animals↗

[Continuous systemic venous oxygen saturation monitoring immediately after Fontan procedure].

Changes in cardiac output (CO), systemic venous oxygen saturation (SvO2), systemic oxygen consumption, and urinary output immediately after Fontan procedure were measured in 10 patients at the intensive unit (ICU) to assess the effects of aorusal from anesthesia, hypothermic management, and respiratory condition. The measurements were taken at the following phases; phase A in deep sedation under hypothermia (33-35 degrees C rectal temperature) and controlled ventilation; phase B in mild sedation under normothermia and controlled ventilation; phase C when awake under normothermia and assisted ventilation; phase D when awake under assisted ventilation; phase D when awake under normothermia immediately after extubation; and phase E 24 hours after extubation. Oxygen delivery (O2 Del.) and fractional oxygen fractions were calculated in each phase. Two patients whose SvO2 values were below 55% during the postoperative course needed reoperation for atrioventricular valve regurgitation in one case for PV stenosis in the other case. CO increased significantly (p < 0.05) after extubation (phase D), compared with that of controlled ventilation (phase B). Under hypothermia (phase A), urinary output was relatively higher with lower CO. There was a significant correlation between SvO2 and CO (R = 0.61) in phase A, however there was no correlation in phase E. Fractional oxygen extraction in phase A was significantly lower than in phase B. In conclusion, the continuous SvO2 measurements reflected real-time changes in cardiac output in the immediate post-Fontan patients. Induced hypothermia was beneficial in increasing urinary output presumably through the correction of maldistribution of cardiac output in post-Fontant patients. Arousal from anesthesia and spontaneous ventilation seemed advantageous for increasing cardiac output, hence, early extubation should be encouraged in the management of post-Fontan patients.

Blood Gas Monitoring, Transcutaneous↗

[Surfactant protein A in bronchoalveolar lavage fluid from patients with idiopathic interstitial pneumonia].

We measured the levels of surfactant protein A (SP-A) in bronchoalveolar lavage fluid from patients with idiopathic interstitial pneumonia and from healthy volunteers. The SP-A levels in the patients who were smokers (1.4 +/- 0.2 micrograms/ml) were significantly (p < 0.05) lower than those in the patients who were nonsmokers (3.0 +/- 0.5 micrograms/ml). However, SP-A levels did not differ significantly between patients and volunteers who were smokers, or between patients and volunteers who were nonsmokers. The ratios of SP-A to phospholipid in patients who were smokers and in those who were non-smokers did not differ significantly from those in volunteers who were smokers and volunteers who were non smokers. The total number of alveolar macrophages in bronchoalveolar lavage fluid did not significantly correlate with the level of SP-A, although the percentage of alveolar macrophages correlated negatively (p < 0.05) with the level of SP-A. The low level of SP-A in patients with idiopathic interstitial pneumonia who are smokers may weaken the host defense functions in peripheral airways and may contribute to the poor outcomes in these patients.

Adult↗

Expression of MAGE-1, MAGE-2, MAGE-3/-6 and MAGE-4a/-4b genes in ovarian tumors.

MAGE genes encoding tumor-rejection antigens recognized by cytotoxic T lymphocytes are expressed at the mRNA level in various malignant tumors. We have investigated the expression of genes MAGE-1, -2, -3/-6 and -4a/-4b at the mRNA level in malignant and non-malignant ovarian tumors as well as in normal ovaries by reverse transcription-polymerase chain reaction. MAGE-1, -2, -3/-6 and -4a/-4b were expressed in 12, 5, 11 and 4 of 58 malignant tumors, respectively. The majority of these MAGE-mRNA-positive tumors were histologically surface-epithelial-stromal tumors, in particular serous adenocarcinomas. They mostly consisted of either advanced-stage or recurrent tumors. In contrast, neither benign tumors nor normal ovaries expressed any of the MAGE genes investigated. A 46-kDa MAGE-1 protein was identified in MAGE-1-mRNA-positive serous adenocarcinomas by immunoblot analysis with polyclonal anti-MAGE-1 antibody. These results provide important information for specific immunotherapy of ovarian serous adenocarcinomas with MAGE gene products.

Amino Acid Sequence↗

Cloning of a novel RNA binding polypeptide (RA301) induced by hypoxia/reoxygenation.

Astrocytes have a critical role in the neuronal response to ischemia, as their production of neurotrophic mediators can favorably impact on the extreme sensitivity of nervous tissue to oxygen deprivation. Using a differential display method, a novel putative RNA binding protein, RA301, was cloned from reoxygenated astrocytes. Analysis of the deduced amino acid sequence showed two ribonucleoprotein domains and serine/arginine-rich domains, suggestive of their function as RNA splicing factor. Northern analysis displayed striking induction only in cultured astrocytes within 15 min of reoxygenation and reached a maximum by 60 min after hypoxia/reoxygenation. Immunoblotting demonstrated expression of an immunoreactive polypeptide of the expected molecular mass, 36 kDa, in lysates of hypoxia/reoxygenated astrocytes. Induction of RA301 mRNA was mediated, in large part, by endogenously generated reactive oxygen species, as shown by diphenyl iodonium, an inhibitor of neutrophil-type nicotinamide adenine dinucleotide phosphate oxidase which blocks oxygen-free radical formation by astrocytes. Similarly, increased expression of RA301 in supporting a neurotrophic function of astrocytes was suggested by inhibition of interleukin-6 elaboration, a neuroprotective cytokine, in the presence of antisense oligonucleotide for RA301. These studies provide a first step in characterizing a novel putative RNA binding protein, whose expression is induced by oxygen-free radicals generated during hypoxia/reoxygenation, and which may have an important role in redirection of biosynthetic events observed in the ischemic tissues.

Aerobiosis↗

Instability of the mutated biotin operon plasmid in a biotin-producing mutant of Serratia marcescens.

The growth of a d-biotin-producing strain of Serratia marcescens (SB412) was strongly inhibited by the introduction of pLGM412, a low-copy-number plasmid containing the complete biotin (bio) operon derived from SB412, whereas the wild-type strain was not inhibited by the plasmid. SB412 carrying pLGM412 was genetically unstable; large colonies appeared spontaneously from the background small colonies. When the plasmids from the large colonies were transformed into the SB412 host, all of the resultant transformants showed a large-colony phenotype, suggesting that the large-colony phenotype is due to mutations in the plasmid-born bio genes. Some of these plasmids were structurally altered and the others were not. Furthermore, the structurally altered plasmids were classified into a deleted and an elongated type. All of the mutated pLGM412 derivatives reduced or lacked the bio gene expression, indicating that the high expression of bio gene(s) causes the growth inhibition. By subcloning experiments, biotin synthase (the bioB gene product) was responsible for the growth inhibition.

Bacterial Proteins↗

HLA A2601-restricted CTLs recognize a peptide antigen expressed on squamous cell carcinoma.

The CD4-CD8+ CTL (KE-4 CTL) cell line against autologous tumor cells was established in a patient with esophageal cancer. This KE-4 CTL recognized a peptide antigen on esophageal and lung squamous cell carcinomas in an HLA A2601-restricted manner, as evaluated by cytotoxicity against a panel of tumor cells, transfection experiments with HLA A2601 cDNA, and reconstitution with eluted peptides. None of the normal cells tested was lysed by this CTL. These results suggest the existence of HLA A2601-restricted CTL precursors recognizing a peptide antigen on SCC in a patient with esophageal cancer.

Antigens, Neoplasm↗

Structure of rat annexin V gene and molecular diversity of its transcripts.

We report here the isolation and characterization of the entire rat annexin V gene, which is shown to span about 40 kbp, and to consist of 14 exons, 13 introns and two promoters. Previous studies found that both human and chicken annexin V genes bear 13 exons and one promoter, which possess no TATA sequence or CCAAT box, and have a high GC content. In the present study, we found that one of the promoters for rat annexin V shares these features, which are typical among promoters for housekeeping genes, and that this promoter, as expected, exerted its transcription in all of tissues we examined. In contrast, another promoter was found to possess not only a TATA box but also a glucocorticoid-responsive element, and was shown to express messages in a relatively limited number of tissues, including brain. We also demonstrated the presence of at least four species of rat annexin V transcripts that were generated by distinct transcription initiation and alternative splicing.

Alternative Splicing↗

Expression, purification, and neurotrophic activity of amyloid precursor protein-secreted forms produced by yeast.

The secreted form of amyloid precursor protein (APPs) including most of the extracellular domain of APP is released from the cell surface, suggesting physiological significance of APPs in vivo. We used the methylotrophic yeast Pichia pastoris as a host system for the production of recombinant APPs (rAPPs). Two rAPPss derived from isoforms of APP (APP695 and APP770) were secreted into the culture medium from the yeast, which carried cDNA encoding the N-terminal portion of APP under the control of a P. pastoris alcohol oxidase promoter. Like APPss produced by the transfected COS-1 cells, the purified rAPPss from yeast were shown to be biologically active in terms of neurite outgrowth of embryonic rat neocortical explants. These rAPPss could be valuable tools for investigating the biological functions of APPss.

Amino Acid Sequence↗

Sequence analysis of the MAGE gene family encoding human tumor-rejection antigens.

The MAGE multigene family, which includes the MAGE-1 and -3 genes that encode tumor-rejection antigens on HLA-A1 recognized by cytotoxic T-lymphocytes (CTL), is preferentially expressed at the mRNA level on human malignant cells, but not on normal cells. However, little is known about the MAGE-4, -41 and -6 genes. In this study, we have amplified 1040 bp (MAGE-1), 1061 bp (MAGE-3 and -6) and 1064 bp (MAGE-4 and -41) cDNA fragments, including the entire coding sequences (927-951 bp), using the reverse transcription-polymerase chain reaction (RT-PCR) method followed by nucleotide (nt) sequencing. One member had greater than 80 or 66% homology with the other members at the nt or deduced amino acid (aa) levels, respectively. Higher homology was found between MAGE-3 and -6 (98% at the nt level) and also between MAGE-4 and -41 (98%). The results of this investigation demonstrated high homology, as well as the clear differences between the members of the MAGE family at the coding sequence level.

Amino Acid Sequence↗

Calcium-dependent conformation of a mouse macrophage calcium-type lectin. Carbohydrate binding activity is stabilized by an antibody specific for a calcium-dependent epitope.

We established monoclonal antibodies (mAbs) against the mouse macrophage galactose/N-acetylgalactosamine-specific lectin (MMGL) that is a 42-kDa calcium-dependent lectin, using a solid phase carbohydrate binding assay as a novel strategy for screening mAbs. The specificity of six mAbs were investigated by antibody binding to native or recombinant forms (rML) of MMGL, flow cytometry, and immunoprecipitation using a macrophage cell line RAW264.7. Four of these mAbs strongly inhibited the binding of fluorescein 5-isothiocyanate-labeled galactosylated polylysine to immobilized rML, one inhibited moderately, and one did not inhibit binding. The competitive binding study revealed that the binding sites of these four blocking mAbs were closely related to each other but were different from the rest of these mAbs. A non-blocking mAb having a unique binding specificity (LOM-11) exhibited calcium-dependent binding to rML, suggesting that calcium-dependent epitope was not situated in the vicinity of the ligand binding site. Furthermore, pretreatment of rML with the mAb LOM-11 preserved ligand binding activity, especially in a low calcium environment. The four blocking mAbs mentioned above facilitated the binding of the mAb LOM-11 to rML. These results indicate that there is a positive cooperativity between the lectin's ligand binding site and its physically distinct calcium-dependent epitope.

Animals↗

Inflammation enhances peripheral mu-opioid receptor-mediated analgesia, but not mu-opioid receptor transcription in dorsal root ganglia.

mu-Opioid receptor agonist [D-Ala2,NMe-Phe4,Gly5-ol]enkephalin (DAMGO)-induced peripheral analgesic effects occur early in hindpaws inoculated with Freund's complete adjuvant and increase in parallel to the development of inflammatory signs. Antagonism of these effects by beta-funaltrexamine, an irreversible mu-opioid receptor antagonist, suggests that the effective number of peripheral opioid receptors does not increase during early stages, but does so at later stages of the inflammation. As determined by a ribonuclease protection assay, mu-opioid receptor mRNA in dorsal root ganglia is abundant in untreated animals, but does not significantly increase following inflammation. Thus, peripheral analgesic efficacy of DAMGO is not correlated with transcription or number of mu-opioid receptors at early inflammatory stages. At later stages, however, the number of peripheral mu-opioid receptors appears to increase and may enhance opioid efficacy.

Amino Acid Sequence↗

Normal sympathetic vasomotor and cardiac parasympathetic activities in patients with primary aldosteronism: assessment by spectral analysis.

The role of the autonomic nervous system in hypertension due to mineralocorticoid excess remains unclear. To address this issue, we performed power spectral analysis of blood pressure (BP) and RR interval oscillations in 20 patients with primary aldosteronism (PA), 54 patients with essential hypertension (EH) and 45 normotensive (NT) subjects. Blood pressure and the degree of organ damage were similar between PA and EH groups. Age did not differ between the three groups. The Mayer wave power spectrum (MWP) of BP (approx. 0.1 Hz), an index of sympathetic vasomotor tone, was smaller in patients with PA than in patients with EH either while subjects were supine (systolic/diastolic; 3.9 +/- 3.2 (SD)/1.5 +/- 1.3 vs. 5.5 +/- 4.2/2.1 +/- 1.6 mmHg2, P < 0.05 for both) or standing (7.6 +/- 6.6/3.0 +/- 3.0 vs. 17.7 +/- 23.7/7.2 +/- 8.3 mmHg2, P < 0.05 for both). Supine respiratory-related power spectrum (RRP) of the RR interval (approx. 0.25 Hz), an index of cardiac parasympathetic tone, was greater in patients with PA than in patients with EH (545 +/- 574 vs. 302 +/- 464 ms2, P < 0.01). The MWP of BP and the RRP of the RR interval were similar between patients with PA and NT subjects. Adrenalectomy reduced the 24-h mean BP (-18 mmHg for systolic BP, P < 0.001; -12 mmHg for diastolic BP, P < 0.01) and increased the 24-h mean heart rate (+8 bpm, P < 0.001). Furthermore, the diastolic MWP increased mildly (+32%, P < 0.05) and the RRP of the RR interval decreased dramatically (-75%, P < 0.01) following adrenalectomy. These results suggest that both vascular sympathetic and cardiac parasympathetic regulatory systems have minor roles in the maintenance of hypertension in patients with PA. The autonomic nervous system contributes more to the maintenance of BP following than prior to adrenalectomy. This information may be useful for the management of hypertension still persists after removal of adrenal adenoma.

Adenoma↗

Attachment and growth of fibroblast cells on silk fibroin.

The attachment and growth of fibroblast cells (L-929) on matrices of silk fibroin from Bombyx mori domestic silkworm (DSF) and Antheraea pernyi wild silkworm (WSF) were studied by a cell culture method. The performance of the two kinds of silk fibroin was compared to that of collagen. DSF exhibited as high a cell attachment and growth as collagen did. The cells attached to DSF were extensively spread out and their filopodia were visible in the SEM pictures. WSF, which contains the tripeptide sequence Arg-Gly-Asp (believed to be a specific interaction site for cell-attachment), displayed much higher cell attachment and growth compared to DSF. The cells attached on WSF became virtually flat and their filopodia could be seen, indicating that the cells were very strongly held on the surface.

Amino Acid Sequence↗

A mutational hot spot in the p53 gene is associated with hepatoblastomas.

Hepatoblastomas generally appear in children aged 2 or 3 years old and arise from apparently normal, non-cirrhotic liver. To elucidate any possible role of p53 mutations in their genesis, we amplified and sequenced exons 5 to 8 of the p53 gene in 10 cases of hepatoblastoma. Somatic mutations were detected in 9 cases, in eight of which a common point mutation at the first-base position of codon 157 was found, resulting in an amino-acid substitution of phenylalanine for valine. Two missense mutations in codon 244, and one each in codons 273 and 279, were also found, with 3 hepatoblastomas having double mis-sense mutations. Out of the total of 12 mutations, 11 were G-to-T transversions. One was a G-to-A transition and guanines were always present on the transcribed strand. Furthermore, p53 over-expression was immunohistochemically observed in 7 out of 9 cases with p53 gene mutations, although the staining pattern was focal and heterogeneous. The findings suggest that particular environmental mutagens may be involved in mutagenesis of the p53 gene in some cases of hepatoblastomas and that p53 mutations at a specific site may play an important role in the genesis of this disease.

Base Sequence↗