Biomedical subjects

S Komatsu

Publications and source records attributed to S Komatsu.

At least 91 records · Page 5Linked to original sources

PubMed1997

Differential up-regulation of circulating soluble and endothelial cell intercellular adhesion molecule-1 in mice.

Although circulating levels of soluble intercellular adhesion molecule-1 (sICAM-1) are frequently used as an indicator of the severity of different immune, inflammatory, or neoplastic diseases, little is known about the factors that govern plasma sICAM-1 concentration and its relationship to the membranous form of ICAM-1 (mICAM-1) expressed on vascular endothelial cells. Plasma sICAM-1 concentration (measured by enzyme-linked immunosorbent assay) and mICAM-1 expression (measured using the dual radiolabeled monoclonal antibody technique) in different vascular beds (eg, lung, small intestine, and spleen) were monitored in wild-type (C57BL) and ICAM-1-deficient mice, before and after administration of tumor necrosis factor (TNF)-alpha. In wild-type mice, TNF-alpha elicited time-dependent increases in lung and intestine mICAM-1 (plateau achieved at 12 hours), with a corresponding increase in plasma sICAM-1 (peaked at 5 hours and then declined). The initial increases in mICAM-1 and pulmonary leukocyte sequestration (measured as lung myeloperoxidase activity) induced by TNF-alpha preceded any detectable elevation in sICAM-1. In ICAM-1-deficient mice, plasma sICAM-1 was reduced by approximately 70%, with > 95% reductions of mICAM-1 in lung and intestine, and > 75% reduction in splenic accumulation of anti-ICAM-1 antibody. Although TNF-alpha doubled plasma sICAM-1 in ICAM-1-deficient mice, mICAM-1 was unaffected in all tissues. Either splenectomy or pretreatment with cycloheximide resulted in an attenuated TNF-induced increase in sICAM-1, without affecting mICAM-1 expression. These findings indicate that plasma sICAM-1 concentration does not accurately reflect the level of ICAM-1 expression on endothelial cells in different vascular beds.

Animals↗

PubMed1996

ASABF, a novel cysteine-rich antibacterial peptide isolated from the nematode Ascaris suum. Purification, primary structure, and molecular cloning of cDNA.

Previously, we reported antibacterial activity in the body fluid of the nematode Ascaris suum (Kato, Y. (1995) Zool. Sci. 12, 225-230). The antibacterial activity is due to a heat-stable and trypsin-sensitive molecule that was designated as ASABF (A. suum antibacterial factor). In the present study, the purification, determination of primary structure, and cDNA cloning of ASABF were carried out. The mature peptide of ASABF is a basic peptide consisting of 71 residues and containing four intramolecular disulfide bridges. The amino acid sequence of a precursor for ASABF, deduced from a cDNA clone, indicates that flanking peptides both at the N terminus and at the C terminus are eliminated by processing. ASABF exhibits potent antibacterial activity particularly against Gram-positive bacteria. ASABF has several features that resemble those of insect/arthropod defensins, whereas the statistical significance of the similarity is not observed on comparison of amino acid sequences. A search of data bases revealed ASABF homologues in Caenorhabditis elegans.

Amino Acid Sequence↗

PubMed1996

Phosphorylation by MAPKAP kinase 2 activates Mg(2+)-ATPase activity of myosin II.

Mitogen-activated protein kinase activated protein (MAPKAP) kinase-2 was found to phosphorylate the regulatory light chain of myosin II (MRLC) in vitro in the absence of Ca2+/calmodulin. The tryptic peptides recovered from the MRLC phosphorylated by MAPKAP kinase-2 were identical to the phosphopeptides recovered from myosin light chain kinase (MLCK)-phosphorylated MRLC. Phosphoamino acid analysis revealed that MRLC was phosphorylated by these kinases at the serine residue. This phosphorylation by MAPKAP kinase-2 activated the actin-activated Mg(2+)-ATPase activity of myosin II. These findings indicated that MAPKAP kinase-2 may be a kinase that regulates the actin-activated Mg(2+)-ATPase activity of myosin II.

Animals↗

PubMed1996

Rice gibberellin-binding phosphoprotein structurally related to ribulose-1,5-bisphosphate carboxylase/oxygenase activase.

A gibberellin A (GA)-binding protein was identified from rice (Oryza sativa L.) leaves by a ligand-binding assay. The dissociation constant of GA-binding protein and GA complex was about 100 nM. This protein has a relative molecular mass of 47 000 and an isoelectric point of 5.1. The partial amino acid sequence of the protein was determined for 54 residues from both the N-terminal and internal regions. A sequence homology search indicated that the amino acid sequence of GA-binding protein was homologous to that of the ribulose-1,5-biphosphate carboxylase/oxygenase activase from barley, Arabidopsis, spinach and Chlamydomonas. The GA-binding protein was immunologically detected in two polypeptides in the protein extract from leaves. The GA-binding protein identified was phosphorylated with Ca2+, Mg2+ and ATP in the leaf protein extracts of rice grown in the presence of exogenous GA.

Amino Acid Sequence↗

PubMed1996

Age-related and intelligence-related differences in implicit memory: effects of generation on a word-fragment completion test.

In two experiments, subjects either read a bracketed word in a sentence or generated a word in response to its definition. A word-fragment completion test was then carried out. In Experiment 1, children's priming under the generate condition was substantial, as compared with baseline performance, but was significantly lower than that under the read condition, whereas there was no difference in adults' priming between these two conditions. Furthermore, prior generation induced an age-related increase in priming despite no age difference under the read condition. In Experiment 2, mentally retarded persons exhibited a profile similar to that of children. These results suggests that there are two different components in implicit memory, one that shows no developmental difference and heavily relies on perceptual processing and the other that shows an age-related or intelligence-related increase and heavily relies on conceptual processing.

Adolescent↗

PubMed1996

Mitral valve operation after percutaneous transvenous mitral commissurotomy (PTMC): an evaluation of PTMC indications based on intraoperative findings.

Six patients underwent open heart surgery for mitral valve disease after percutaneous transvenous mitral commissurotomy (PTMC) because of recurrent mitral stenosis (MS) in 4, moderate mitral regurgitation (MR) in 1, and acute severe MR in 1. These 6 patients were the only such observed cases out of a total of 86 patients who presented with PTMC in our hospital between October 1989 and May 1995. The duration of the subjective symptoms related to heart failure was 24.1 +/- 11.6 years, ranging from 3 to 30 years. Four of the six patients had had a previous surgical commissurotomy [closed mitral commissurotomy (CMC) in 2 and open mitral commissurotomy (OMC) in 2] from 24 to 30 years earlier (mean 28 years). The intraoperative findings of the 4 with residual MS included severe thickening, calcification on anterior and posterior leaflets, and bilateral commissures. Five patients were noted to have shortening and adhesion in the mitral subvalvular apparatus. Two patients with moderate to severe tears on the anterior leaflets and another two patients with tears on the posterior leaflet were also noticed; however, these leaflets were not severely thickened. It was possible to split and repair the fused commissure in one patient, but the other five required MVR due to severe subvalvular lesions. Therefore, if a patient has bilateral commissural calcification or has less thickend leaflets with severe subvalvular thickening and fusion with a small MVA measuring less than 0.8 cm2 and a MS score of more than 8, the OMC procedure is considered to provide good long-term clinical results. The decision to perform either PTMC or OMC should only be made based on meticulous echo Doppler findings and a hemodynamic evaluation of the mitral valve.

Adult↗

PubMed1996

Ten years' experience of aortic valve replacement with the Omnicarbon valve prosthesis.

BACKGROUND: There are few clinical studies on late follow-up of the Omnicarbon monoleaflet valve. We report our 10-year experience with this valve in the aortic position and also compare late hemodynamic performance of this valve with that of the CarboMedics valve in the aortic position. METHODS: From January 1985 to June 1995, 117 consecutive patients underwent aortic valve replacement (AVR) with the Omnicarbon valve. There were 66 men and 51 women aged 13 to 69 years (mean age, 50 +/- 12 years). They were divided into three groups: group 1 (43 patients) had isolated AVR, group 2 (36) had AVR and concomitant operations, and group 3 (38) had combined AVR and mitral valve replacement. Follow-up was 96.6% complete and consisted of 882.7 patient-years (range, 2.5 to 10.6 years; mean follow-up, 7.5 +/- 2.7 years). RESULTS: There were three early deaths (2.6%) and 18 late deaths (2.0%/patient-year) ten of which were due to valve-related causes and eight, non-valve-related causes. Survival rates at 10 years in groups 1, 2, and 3 were 77.6%, 82.4%, and 78.6%, respectively. The overall rates of freedom from valve-related complications in groups 1, 2, and 3 at 10 years were 77.4%, 100%, and 80.9%, respectively. The rates of freedom from the following complications in groups 1, 2, and 3 at 10 years were as follows: thromboembolism--94.8%, 100%, and 89.4%, respectively; valvar thrombosis--95.0%, 100%, and 100%; anticoagulant-related hemorrhage--93.6%, 100%, and 93.4%; prosthetic valve endocarditis--93.0%, 100%, and 97.2%; and reoperation--90.6%, 100%, and 97.2%. There were no significant differences between groups. All survivors showed marked improvement in New York Heart Association functional class, from 86% in classes III and IV preoperatively to 96% in classes I and II postoperatively. The Omnicarbon valve exhibited no significant difference in hemodynamic performance after isolated AVR compared with the CarboMedics bileaflet valve at the same follow-up periods. CONCLUSIONS: This 10-year study confirms that the Omnicarbon valve is a durable prosthesis and provides excellent functional improvement with low rates of thromboembolism and valvar thrombosis in the aortic position.

Adolescent↗

PubMed1996

Comparative experimental study of cerebral protection during aortic arch reconstruction.

BACKGROUND: The optimal adjunctive method for cerebral protection during aortic arch repair remains controversial. METHODS: Retrograde cerebral perfusion, selective cerebral perfusion, and hypothermic circulatory arrest were compared in terms of their effect on cerebral function of mongrel dogs using somatosensory evoked potentials. Brain temperatures were held at 20 degrees C for 90 minutes during cerebral perfusion or circulatory arrest and then rewarmed gradually to normal temperature. RESULTS: Somatosensory evoked potentials completely disappeared as soon as retrograde cerebral perfusion or hypothermic circulatory arrest started and did not recover completely. In the selective cerebral perfusion group, it recovered in all cases. Only 2% of cerebral blood flow and about 3% of the cerebral metabolic rate for oxygen were obtained during retrograde cerebral perfusion compared with the preoperative value. The analysis of adenosine triphosphate and water content of the brain supported these results. CONCLUSIONS: Retrograde cerebral perfusion had some advantage for cerebral protection compared with hypothermic circulatory arrest, but could not supply sufficient cerebral blood flow to maintain brain function. Selective cerebral perfusion was the safest method for arch reconstruction that requires cerebral protection for 90 minutes.

Animals↗

PubMed1996

Successful repair of coronary artery-coronary sinus fistula with aneurysm in an adult.

We report a very rare case of an adult with coronary artery fistula and aneurysm formation. This fistula was successfully closed with direct suture closures by opening the aneurysm under complete cardiopulmonary bypass. The distal terminated orifice of the fistula, which drained to the coronary sinus, was also closed. Finally, aneurysmorrhaphy with overlapping mattress sutures was performed. The postoperative angiographic study demonstrated normal coronary artery distribution, and the patient was asymptomatic without recurrence at 2 years after the operation.

Coronary Aneurysm↗

PubMed1996

Effects of high-density lipoproteins on intracellular pH and proliferation of human vascular endothelial cells.

We investigated the effects of high-density lipoprotein (HDL) on the intracellular pH ([pH]i), and on the proliferation of human vascular endothelial cells (HUVEC), as well as on their production of prostacyclin (PGI2). The [pH]i was slightly acidified when extracellular Ca2+ was chelated with EGTA. Pretreatment of HUVEC with amiloride, the Na+/H+ exchange inhibitor, caused the [pH]i to become strongly acidic. The addition of HDL produced a biphasic shift in [pH]i, with a brief initial acidification followed by a rapid alkaline shift. The initial decrease in [pH]i was abolished in the cells pretreated with EGTA, and subsequent alkalinization was inhibited. The alkalinization of [pH]i disappeared in the cells pretreated with amiloride. These results suggest that [pH]i depends mainly on Na+/H+ exchange and partially on the extracellular Ca2+ of the HUVEC either in the resting unstimulated state or during HDL stimulation. In contrast, the addition of LDL produced an acidification of [pH]i, which was increased by LDL in the Ca(2+)-free condition. In the cells pretreated with amiloride, [pH]i was not further acidified by LDL. As a result, HDL promoted the proliferation of cells, an action that was inhibited by pretreatment with EGTA. However LDL inhibited cell proliferation, an action unaffected by EGTA pretreatment. The addition of HDL also enhanced the generation of prostacyclin in endothelial cells, the enhancement of PGI2 generation resulted from an increase in the release of Ca2+ from storage sites, due not only to an increased production of inositol 1,4,5-trisphosphate (IP3), but also to the alkalinization of [pH]i. These effects may be involved in the mechanism of HDL's anti-atherosclerotic action.

Amiloride↗

PubMed1996

Partial purification and characterization of a calcium-dependent protein kinase in rice leaves.

A protein from rice leaves, which was partially purified by sequential chromatography on DE52, MONO-Q and Superose 12, presented calcium-dependent protein kinase (CDPK) activity. This protein kinase phosphorylated the substrate, histone III-S, in a Ca(2+)-dependent manner and the half-maximum concentration of Ca2+ to protein kinase activity (EC50) was 1 microM. This phosphorylation was independent of phosphatidylserine and a phorbol ester. The apparent M(r) of the protein kinase, as determined by phosphorylation in SDS-polyacrylamide gel containing histone III-S, was 45 k. This kinase was found to react differently from other protein kinases, such as protein kinase C from rat brain or CDPK from soybean leaves, owing to the absence of a phospholipid or phorbol ester dependency. CDPK phosphorylated three endogenous proteins as detected by in vitro phosphorylation on two-dimensional PAGE.

Animals↗

PubMed1996

Contralateral lung injury associated with single-lung ischemia-reperfusion injury.

BACKGROUND: There have been very few studies on the effect of single-lung ischemia-reperfusion on the function of the contralateral lung. This study was designed to clarify the effect. METHODS: Fifteen mongrel dogs were divided into two groups. In group 1 (n = 7), the left lung was subjected to ischemia without ventilation for 90 minutes, and then reperfused. In group II (n = 8), the lung was not subjected to ischemia, and was ventilated during the 90-minute ischemia of group I. Arterial blood gas, hemodynamics, extravascular lung water, and airway pressure were measured. Pulmonary biopsy was performed to evaluate adenine nucleotide levels. The protein concentration and phosphorous concentration of phospholipids in bronchoalveolar lavage fluid were measured. RESULTS: Group I, with perfusion and ventilation of the right lung alone, was significantly inferior to group II with respect to arterial blood gas, right pulmonary compliance, extravascular lung water of the right lung, and the protein concentration in the bronchoalveolar lavage fluid of the right lung after the 90-minute period. CONCLUSIONS: These results indicate that 90 minutes of warm ischemia and reperfusion of the left lung caused deterioration of not only the left but also contralateral right pulmonary function.

Adenine Nucleotides↗

PubMed1996

Extended aortic replacement for acute type A dissection with the tear in the descending aorta.

OBJECTIVE: There has been controversy as to the selection of surgical treatments for acute type A dissection with the tear in the descending thoracic aorta, a subtype of acute aortic dissection in which the limited tear is located distal to the left subclavian artery but the dissection extends retrogradely to the ascending aorta. METHODS: Total replacement of the ascending aorta and aortic arch was performed in 12 patients with acute type A dissection with the tear in the descending thoracic aorta between March 1991 and the end of September 1995. The indications for total replacement of the ascending aorta and aortic arch were cardiac tamponade, acute aortic regurgitation, cerebral ischemia, and dilatation of the ascending aorta. The operation was performed with the aid of extracorporeal circulation, blood cardioplegia, selective cerebral perfusion, and open distal anastomosis. The surgical procedure used was total replacement of the ascending aorta and aortic arch with a graft provided with three limbs accompanied by resection of the intimal tear in the descending thoracic aorta. RESULTS: Hospital death occurred in two patients (16.7%). In both, death was due to dissection/related complications of renal/mesenteric ischemia. The other 10 patients have had uneventful postoperative courses over a mean period of 24 months. CONCLUSIONS: Total replacement of the ascending aorta and aortic arch accompanied by resection of an intimal tear distal to the left subclavian artery seems to be justified in selected patients with acute type A dissection with the tear in the descending thoracic aorta.

Acute Disease↗

PubMed1996

Species difference in the disposition of liposomes among mice, rats, and rabbits: allometric relationship and species dependent hepatic uptake mechanism.

PURPOSE: The species difference in the pharmacokinetics of liposomes was investigated in mice, rats and rabbits. METHODS: Liposomes were intravenously injected at doses of 1, 10 and 100 (nmol/g body weight), and the time courses of liposomes in blood, liver and spleen were measured. Pharmacokinetic parameters were regressed as a function of body weight (BW) and dose of liposomes (D). The uptake mechanism of liposomes was also examined with the isolated perfused liver between rats and mice. RESULTS: Mean residence time increased with the increase of BW and D of liposomes. This increase of mean residence time resulted from the decreased total body clearance, which was principally explained by the species difference in the hepatic uptake clearance (CLh) of liposomes. The parameter CLh was regressed well by a multiple regression as a function of BW and D. In this analysis, an exponent for BW was around 0.5, which clearly indicates that smaller animals have higher uptake clearance per unit BW. Immunohistochemical analysis revealed that there was no significant difference in the density of Kupffer cells among these species. This suggest that the species difference in CLh resulted not from the density of Kupffer cells but from the uptake ability of Kupffer cells among species. In the isolated perfused liver, the hepatic uptake of liposomes was mainly explained by opsonin dependent uptake in rats, while opsonin independent uptake in mice. CONCLUSIONS: These quantitative and qualitative information on the species difference of liposome disposition will provide an useful information for constructing a drug delivery system using liposomes.

Animals↗

PubMed1996

Decreased serum retinol levels in women with cervical dysplasia.

To examine the relationship of dietary and serum vitamin A to the risk of cervical dysplasia, a case-control study was conducted in Miyagi, Japan. Cases were 137 women who were found by Papanicolaou test screening and histological examination provided by Miyagi Cancer Society between October 1987 and September 1988 to have cervical dysplasia. Controls were selected from participants of the general health examination provided by the Society and individually matched to cases on age and screening date. The consumption of retinol or carotene-rich foods during the past 7 days was assessed at interview. Information was also collected about other risk factors of cervical dysplasia, such as reproductive histories and sexual behaviour. The mean serum retinol levels were significantly lower among cases compared with controls, although dietary intake levels of retinol and carotene were not different between the two groups. When examined by tertile, the risk of cervical dysplasia was significantly higher among women in the highest tertile of dietary vitamin A level. An inverse association was observed between serum retinol level and risk of cervical dysplasia, although it did not achieve statistical significance.

Adolescent↗

PubMed1996

The independent association of smoking and drinking with serum beta-carotene levels among males in Miyagi, Japan.

BACKGROUND: Previous studies indicated that serum beta-carotene levels were low among smokers and drinkers. However these findings may result from the strong relationship between smoking and drinking. METHODS: Data were collected from 1902 males randomly selected from participants of a cohort study. The effects of smoking on serum beta-carotene levels were assessed according to drinking status (non-drinker, ex-drinker and current drinker), and those of drinking were assessed according to smoking status (ex-smoker and current smoker) using general linear model including other factors (age, intake of green-yellow vegetables, intake of carrot or pumpkin, body mass index serum cholesterol levels.) RESULTS: An inverse dose-response relationship between daily consumption of alcohol and beta-carotene levels was observed regardless of smoking status, and also between number of cigarettes smoked per day and beta-carotene levels regardless of drinking status. CONCLUSION: These results suggest that cigarette smoking and alcohol drinking reduce beta-carotene levels independently.

Adult↗

PubMed1996

Phosphorylation of a protein (pp56) is related to the regeneration of rice cultured suspension cells.

Short-term cultured suspension cells of rice (Oryza sativa L.) are capable of regeneration, but not in long-term culture. For clarification of the mechanism of regeneration, protein phosphorylation in short-term and long-term cultured suspension cells was compared by two dimensional-polyacrylamide gel electrophoresis. A 56 kDa protein having an isoelectric point of 4.5 was phosphorylated in vitro in short-term cultured suspension cells, but was not phosphorylated after regeneration. This protein in long-term cultured suspension cells remained phosphorylated after transfer to the regeneration medium. However, using an antibody raised against this protein from short-term cultured suspension cells, it was always detected in long-term and short-term cultured suspension cells after transfer to the regeneration medium. The partial amino acid sequence of the HPLC-purified protein showed homology to a calcium-binding protein from maize. The phosphorylation of the 56 kDa protein (pp56) appears to be associated with the regeneration of cultured rice cells.

Amino Acid Sequence↗

PubMed1996

Long-term acceptance of major histocompatibility complex-mismatched cardiac allograft induced by a low dose of CTLA4IgM plus FK506.

The immunosuppressant FK506 prolongs allograft survival. However, at therapeutic doses it has significant side effects. A fusion protein consisting of the extracellular portion of CTLA4 and the Fc portion of human IgG (CTLA4IgG) also prolongs allograft survival, but large doses of CTLA4IgG are required for the induction of cardiac allograft acceptance. Therefore, we constructed a pentameric form of a new CTLA4 fusion protein, CTLA4IgM. We tested whether low doses of CTLA4IgG or CTLA4IgM in combination with subtherapeutic doses of FK506 can prolong allograft survival in a synergistic fashion. C57BL/6 (H-2b) neonatal hearts were transplanted to CBA/J (H-2b) mice in a heterotopic, nonvascularized cardiac allograft model. The findings demonstrate that a combination of low doses of FK506 plus a pentameric form of CTLA4Ig, CTLA4IgM, leads to significant graft survival, while a combination of FK506 plus CTLA4IgG does not.

Abatacept↗