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Biomedical subjects

N Hayashida

Publications and source records attributed to N Hayashida.

At least 91 records · Page 5Linked to original sources
PubMed1995

Myocardial protection for coronary bypass grafting: the Toronto Hospital perspective.

BACKGROUND: The contemporary results of coronary artery bypass grafting using a variety of myocardial preservation techniques are excellent. In recent years, the number of "high-risk" patients referred for operation has increased, thus necessitating continued advances in surgical myocardial protection. METHODS: In this article, we review recent advances in clinical myocardial protective techniques and emphasize studies conducted at The Toronto Hospital. Further, on the basis of promising current research, we speculate on future prospects for myocardial protection. RESULTS: At The Toronto Hospital, we converted from crystalloid to intermittent cold blood cardioplegia in 1985. We demonstrated that "continuous" cardioplegic strategies may help resuscitate the ischemic myocardium and reduce operative complications in high-risk patients. Further improvements in myocardial protection will require refinements in cardioplegic solution temperature, direction of delivery, and additives to "precondition" the myocardium against ischemic damage. CONCLUSIONS: Major advances that meet the requirements of an increasingly high risk patient population have been made in surgical myocardial protection in recent years. The future is bright for continued progress in this area.

Blood↗
PubMed1995

Adequate distribution of warm cardioplegic solution.

Seventy-five patients undergoing coronary artery bypass grafting were randomized to receive warm antegrade (N = 25), warm retrograde (N = 25), or a combination of warm antegrade and retrograde (N = 25) delivery of blood cardioplegic solution. Myocardial oxygen utilization, lactate and acid metabolism, and adenine nucleotides and their degradation products were measured during the operation and cardiac function was assessed postoperatively. Warm retrograde delivery of cardioplegic solution increased lactate and acid release during cardioplegia and reperfusion, decreased left ventricular adenosine triphosphate concentrations, and reduced the washout of adenine nucleotide degradation products from both left and right ventricles. Warm antegrade delivery of cardioplegic solution resulted in less lactate and acid release during cardioplegia but more lactate accumulated in the territory of the left anterior descending artery during the crossclamp period. Intermittent antegrade delivery of the cardioplegic solution during combination cardioplegia washed out lactate and acid, which suggested inhomogeneous delivery of the cardioplegic solution during continuous retrograde cardioplegia. Combination cardioplegia best preserved adenosine triphosphate in the left ventricle and resulted in the best postoperative left and right ventricular function. A combination of intermittent antegrade and continuous retrograde delivery of cardioplegic solution provided better myocardial protection than either antegrade or retrograde delivery of cardioplegic solution alone.

Adenine Nucleotides↗
PubMed1995

Interrupted warm blood cardioplegia for coronary artery bypass grafting.

Continuous warm blood cardioplegia has been used with good clinical outcome in both antegrade and retrograde delivery. However, the continuous delivery of cardioplegia is sometimes interrupted for adequate visualization and flow is not constant with heart manipulation during operation. We studied the effects of interrupted antegrade delivery of warm blood cardioplegia on myocardial metabolism and clinical results after surgery. Fifty-five patients undergoing isolated coronary bypass surgery received warm blood cardioplegia (n = 29) or cold crystalloid cardioplegia (n = 26) in an antegrade fashion. During reperfusion, myocardial oxygen consumption, lactate extraction, creatinine kinase isoenzyme (CK-MB), and malondialdehyde (MDA) were measured. Post-operatively, serum CK-MB and cardiac output (CO) were determined over a period of time. Myocardial oxygen extraction in the warm group was significantly greater than in the cold group 1 min after reperfusion (P < 0.02). The results revealed a tendency for patients in the warm group to have prior lactate extraction, although the difference did not reach statistic difference (P < 0.10). After removal of the aortic cross-clamp, the heart returned to sinus rhythm spontaneously in 90% of the patients with warm cardioplegia and 15.4% of those with a cold heart (P < 0.01). Postoperatively, there was no significant CK-MB or MDA release in either group except for one patient with perioperative myocardial infarction. After operation inotropic support was required for two and one patient in the warm and cold groups, respectively, although there were significantly more patients with poor left ventricular function in the warm, than in the cold, group (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

A novel Ti-plasmid-convertible lambda phage vector system suitable for gene isolation by genetic complementation of Arabidopsis thaliana mutants.

A new lambda phage vector system, lambda TI, has been constructed to facilitate genetic complementation of higher plant mutations. The lambda TI vectors are stable, and by using the Cre-lox site-specific recombination, are automatically convertible into Ti-plasmid binary vectors which are capable of expressing genes in higher plants. Two lambda TI vectors were constructed: (i) lambda TI1, which can generate a Ti-plasmid that contains the cauliflower mosaic virus (CaMV) 35S promoter and is suitable for the expression of cDNA in transformed plants and (ii) lambda TI2, which can generate a Ti-plasmid with the multicloning site (MCS). cDNA and genomic libraries, which were constructed from the cruciferous plant Arabidopsis thaliana in these lambda TI vectors, can be probed by large DNA fragments of more than 100 kb, such as yeast artificial chromosomes (YACs), enabling the direct screening of the clones in the chromosome region containing a specified genetic locus. These libraries will certainly become powerful tools for the genetic complementation of Arabidopsis mutant phenotypes by quickly providing transformation-competent clones.

Agrobacterium tumefaciens↗
PubMed1995

Beneficial effect of steroid on myocardial preservation in isolated rat hearts.

Myocardial injury after heart storage has been known to contribute to an increase in myocardial calcium content or oxygen free radical production. The present experiment was designed to determine the inhibitory effect of steroid in the preservation solution on myocardial injury during simple immersion of isolated rat hearts. The experimental group was divided into 5 sub-groups according to the concentration of steroid added to the solution. Group I was stored in preservation solution containing no steroid. Groups II to V were stored in preservation solutions containing methylprednisolone in concentrations of 50 mg/L, 100 mg/L, 150 mg/L, and 200 mg/L, respectively. After the rat hearts were isolated, crystalloid cardioplegic solution at 4 degrees C was used for cardiac arrest, and the hearts were immersed in 4 degrees C Euro-Collins solution for 8 h. Hearts were then maintained under ischemic conditions at 25 degrees C for 15 min. After 60 min of reperfusion at 37 degrees C, cardiac function was measured and biochemical analyses of coronary effluent and myocardium were performed. The cardiac outputs in groups IV and V were significantly higher than those in groups I and II (p < 0.01). Creatine kinase-MB in coronary effluent in groups IV and V were significantly lower than those in groups I and II at 15, 30 and 60 min after reperfusion (p < 0.05). The level of arachidonic acid at 1 and 5 min, and the level of malondialdehyde at 5 min, after reperfusion in groups III, IV and V were significantly lower than those in groups I and II. Myocardial adenosine triphosphate was most preserved in group IV, and myocardial arachidonic acid, malondialdehyde, and calcium levels and water content in groups IV and V were lower than those in groups I and II. Ultrastructural observations also showed that myofilaments and mitochondria were well preserved in groups III, IV and V at 15 min after reperfusion compared with those in groups I and II. These results indicate that the addition of steroid to preservation solution might be effective in preventing myocardial injury during preservation of rat hearts, and the optimal concentration appears to range from 150 mg/L to 200 mg/L.

Actin Cytoskeleton↗
PubMed1995

[Use of inferior epigastric artery for coronary artery bypass grafting].

The usefulness of the free inferior epigastric artery (IEA) as a coronary bypass graft was studied. Among 149 patients for coronary bypass grafting (CABG) between October 1992 and December 1994, the free IEA was used in 12 patients. The mean number of distal anastomosis was 3.7 per patient. The mean distal size of the IEA was 1.3 mm in diameter and the mean length was 9.4 cm. The IEA graft was anastomosed to the obtuse marginal branch in 5, to the diagonal branch in 4, and the right ventricular branch in 3. The proximal anastomosis of the IEA was constructed to the ascending aorta in three and to the saphenous vein (SVG) or to the internal thoracic artery (ITA) in 4 or 5, respectively. Postoperative angiogram demonstrated patent graft in ten and occluded graft in two in whom the size of IEA was less than 1.0 mm in distal diameter and the IEA was anastomosed to the aorta or to the SVG. The IEA was considered to be useful alternative arterial graft when it was used as "interposed graft" of which proximal anastomosis was made to the ITA and size-matching of the graft to the coronary artery was appropriate. The long-term patency of the graft can determine the true efficacy of the IEA for CABG.

Aged↗
PubMed1994

Two genes that encode Ca(2+)-dependent protein kinases are induced by drought and high-salt stresses in Arabidopsis thaliana.

Two cDNA clones, cATCDPK1 and cATCDPK2, encoding Ca(2+)-dependent, calmodulin-independent protein kinases (CDPK) were cloned from Arabidopsis thaliana and their nucleotide sequences were determined. Northern blot analysis indicated that the mRNAs corresponding to the ATCDPK1 and ATCDPK2 genes are rapidly induced by drought and high-salt stress but not by low-temperature stress or heat stress. Treatment of Arabidopsis plants with exogenous abscisic acid (ABA) had no effect on the induction of ATCDPK1 or ATCDPK2. These findings suggest that a change in the osmotic potential of the environment can serve as a trigger for the induction of ATCDPK1 and ATCDPK2. Putative proteins encoded by ATCDPK1 and ATCDPK2 which contain open reading frames of 1479 and 1488 bp, respectively, are designated ATCDPK1 and ATCDPK2 and show 52% identity at the amino acid sequence level. ATCDPK1 and ATCDPK2 exhibit significant similarity to a soybean CDPK (51% and 73%, respectively). Both proteins contain a catalytic domain that is typical of serine/threonine protein kinases and a regulatory domain that is homologous to the Ca(2+)-binding sites of calmodulin. Genomic Southern blot analysis suggests the existence of a few additional genes that are related to ATCDPK1 and ATCDPK2 in the Arabidopsis genome. The ATCDPK2 protein expressed in Escherichia coli was found to phosphorylate casein and myelin basic protein preferentially, relative to a histone substrate, and required Ca2+ for activation.

Adaptation, Biological↗
PubMed1994

The optimal cardioplegic temperature.

Seventy-two patients undergoing coronary artery bypass grafting were randomized to receive cold (8 degrees C) antegrade or retrograde, tepid (29 degrees C) antegrade or retrograde, or warm (37 degrees C) antegrade or retrograde blood cardioplegia (n = 12 in each group). Myocardial oxygen utilization as well as lactate and acid metabolism were assessed intraoperatively and cardiac function was assessed postoperatively. Myocardial oxygen consumption and anaerobic lactate release were greatest during warm, intermediate during tepid, and least during cold cardioplegic arrest. Myocardial oxygen consumption and lactate release were underestimated during retrograde cardioplegia because of contamination of aortic root samples. Warm retrograde and tepid retrograde cardioplegia resulted in greater lactate and acid washout with reperfusion. Left ventricular stroke work indices were greater after warm antegrade and tepid antegrade cardioplegia than after cold antegrade cardioplegia, and right ventricular stroke work indices were greatest after warm antegrade cardioplegia. Warm antegrade cardioplegia increased aerobic metabolism during and after cardioplegia and preserved left and right ventricular function. Tepid antegrade cardioplegia reduced anaerobic lactate and acid release during arrest and preserved cardiac function.

Adult↗
PubMed1994

Proof of fallout endothelialization of impervious Dacron grafts in the aorta and inferior vena cava of the dog.

PURPOSE: The purpose of this study was to prove directly whether cells from the blood stream contribute to endothelialization of isolated, impervious Dacron vascular grafts in the dog. METHODS: We designed an 18 cm, three-component graft with two parallel central Dacron limbs; one was made impervious with silicone rubber, and the other was preclotted. This model was implanted in the canine descending thoracic aorta with 30 microns polytetrafluoroethylene grafts anastomosed at each end. An 8 cm, three-component graft completely coated with silicone rubber was implanted in the canine abdominal aorta and inferior vena cava. Implant periods ranged from 4 to 12 weeks. Flow surfaces were studied by use of stereomicroscopy after being stained with silver nitrate, and by use of scanning and transmission electron microscopy, the inner wall and flow surface were studied by light microscopy after hematoxylin-eosin and immunocytochemical staining (the latter for endothelial and smooth muscle cells), and the full wall was studied by light microscopy after hematoxylin-eosin staining. RESULTS: Effective prevention of pannus and transmural ingrowth into the impervious central test grafts was achieved, and scattered islands of endothelial cells were conclusively demonstrated on flow surfaces in each of the three implant sites 4 weeks after implantation. In the descending thoracic aorta, where these grafts were also implanted for 8 and 12 weeks, alpha-actin-positive cells and microvessels were found beneath some of the endothelial islands. CONCLUSION: Fallout endothelialization of Dacron vascular grafts occurs in both the arterial and venous systems of the dog.

Animals↗
PubMed1994

Characterization of two cDNAs that encode MAP kinase homologues in Arabidopsis thaliana and analysis of the possible role of auxin in activating such kinase activities in cultured cells.

Two cDNA clones, cATMPK1 and cATMPK2, encoding MAP kinases (mitogen-activated protein kinases) have been cloned from Arabidopsis thaliana and their nucleotide sequences have been determined. Putative proteins encoded by ATMPK1 and ATMPK2 genes, designated ATMPK1 and ATMPK2, contain 370 and 376 amino acid residues, respectively, and are 88.7% identical at the amino acid sequence level. ATMPK1 and ATMPK2 exhibit significant similarity to rat ERK2 (49%) and Xenopus MAP kinase (50%). The amino acid residues corresponding to the sites of phosphorylation (Thr-Glu-Tyr) that are involved in the activation of MAP kinases are conserved in ATMPK1 and ATMPK2. Northern blot analysis indicates that the ATMPK1 and ATMPK2 mRNAs are significantly present in all the organs except seeds. Genomic Southern blot analysis suggests that there are a few additional genes that are related to ATMPK1 and ATMPK2 in the Arabidopsis genome. Purified Xenopus MAP kinase kinase (MAPK kinase) phosphorylates ATMPK1 and ATMPK2 proteins that have been expressed in Escherichia coli, activating these enzymes. A rapid and transient activation of 46-kDa protein kinase activity that phosphorylated myelin basic protein (MBP) was detected when auxin-starved tobacco BY-2 cells were treated with synthetic auxin, 2,4-dichlorophenoxyacetic acid (2,4-D). Protein kinase activities which phosphorylated the recombinant ATMPK2 protein also increased rapidly after auxin treatment in the auxin-starved BY-2 cells. These results suggest that auxin may function as an activator of plant MAP kinase homologues, as do various mitogens in animal systems.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1994

Microheterogeneity of PSI-E subunit of photosystem I in Nicotiana sylvestris.

Microheterogeneity of a photosystem I (PSI) subunit encoded by a nuclear gene psaE was examined in Nicotiana sylvestris, with the aid of cDNA cloning, peptide mapping analysis and protein sequencing. The psaE product of this plant has four isoforms whose mobilities in PAGE are slightly different from each other. We isolated two types of psaE cDNAs from a N. sylvestris cDNA library, and designated the corresponding genes as psaEa and psaEb, respectively. The psaEa and psaEb genes are 77% homologous at DNA level, and their translation products share 80.4% homology for the precursor proteins and 89.1% for the mature forms. Comparative analysis of the four isoproteins and the putative products of the two psaE genes revealed that two isoproteins out of four are derived from psaEa gene, and the difference between these two isoproteins lies in the respective presence or absence of N-terminal alanine. Likewise, the other two proteins are derived from psaEb with similar N-terminal heterogeneity. These results indicate that multi-gene organization and heterogeneous N-terminal formation at post-translational level are two possible causes for PSI subunit polymorphism in isogenic plant lines.

Amino Acid Sequence↗
PubMed1994

Optimal flow rates for retrograde warm cardioplegia.

Retrograde delivery of warm blood cardioplegia may improve nutrient cardioplegic flow beyond coronary obstructions, but may not adequately perfuse the right ventricle and the posterior left ventricle. To determine the optimal flow rate for warm retrograde cardioplegia, we assessed 62 patients undergoing elective coronary artery bypass in two studies. In the low flow study, administration of 50 ml/min (n = 9), 75 ml/min (n = 11), or 100 ml/min (n = 7) was associated with high lactate production and oxygen extraction during cardioplegic administration. At 50 minutes of cardioplegic arrest, the coronary venous effluent pH was low in all groups. In the high flow study, 30 patients all received flow rates of 100, 200, and 300 ml/min in randomized order during the crossclamp period. In addition, five patients received cardioplegia at a rate of 500 ml/min for the duration of the crossclamp period. Administration of 200 ml/min or higher minimized lactate production and maintained coronary venous pH within the physiologic range, but flows of 300 ml/min or higher did not increase oxygen use or reduce lactate or acid production. Patients in the low flow groups had significantly greater myocardial lactate release during cardioplegic infusion and after removal of the crossclamp than the high flow group. Warm retrograde cardioplegia should be delivered at flow rates of at least 200 ml/min during elective coronary artery bypass operations.

Adult↗
PubMed1993

ATMPKs: a gene family of plant MAP kinases in Arabidopsis thaliana.

We previously reported two cDNAs for MAP kinases (cATMPK1 and cATMPK2) from a dicot plant, Arabidopsis thaliana. We describe here the cloning and characterization of five additional cDNAs encoding novel MAP kinases in Arabidopsis, cATMPK3, cATMPK4, cATMPK5, cATMPK6, and cATMPK7. The amino acid residues corresponding to the sites of phosphorylation (Thr-Glu-Tyr) that are involved in the activation of animal MAP kinases are conserved in all the seven putative ATMPK proteins. Genes for MAP kinases in Arabidopsis constitute a family that contains more than seven members. Sequence analysis suggests that there are at least three subfamilies in the family of Arabidopsis genes for MAP kinases.

Amino Acid Sequence↗
PubMed1993

The gene encoding a calcium-dependent protein kinase located near the sbe1 gene encoding starch branching enzyme I is specifically expressed in developing rice seeds.

A gene (spk) encoding a Ca(2+)-dependent protein kinase (SPK) is located in the region immediately upstream of the sbe1 gene encoding a starch branching enzyme. The spk gene is specifically expressed in developing seeds and its expression pattern is very similar to those of genes encoding starch-synthesizing enzymes such as sbe1 and waxy, seed lipid-synthesizing enzymes, as well as genes encoding seed storage proteins. A full-length spk cDNA was isolated from a cDNA library constructed from developing seeds. The deduced amino acid sequence showed that SPK has a high degree of homology to soybean and carrot Ca(2+)-dependent protein kinase, both of which contain calmodulin domains. The calmodulin domain, as well as the catalytic subdomain consensus regions of protein kinases are highly conserved in SPK. These results suggest that a tissue- and stage-specific protein kinase, SPK, is involved in the synthesis of seed storage compounds during seed development. They also strongly suggest that Ca2+ is required for seed development.

1,4-alpha-Glucan Branching Enzyme↗