Biomedical subjects

K Yamana

Publications and source records attributed to K Yamana.

At least 19 recordsLinked to original sources

PubMed1992

Partial brachiocephalic perfusion under hypothermic cardiopulmonary bypass. An experimental study.

We studied electrophysiological, oxygen metabolic, and histological variables in dogs to establish the reliability and safety of partial brachiocephalic perfusion (PBP) under hypothermic cardiopulmonary bypass (CPB) at 23 degrees-25 degrees C. Sixteen mongrel dogs were divided into two groups. Six (control group) underwent typical hypothermic CPB for 90 min, and 10 (PBP group) underwent PBP under hypothermic CPB for 90 min. During core cooling on the CPB, a progressive reduction in voltage and slowing of frequency of the electroencephalogram (EEG) was observed. At around 23 degrees C nasopharyngeal temperature the tracing became almost flat and remained so throughout the hypothermic CPB or the PBP under hypothermic CPB. Consistent recovery of the EEG was, however, observed during the period of rewarming on the CPB, and the voltage and frequency of the EEG recovered to control levels on weaning off CPB at 36 degrees C in both groups. In the PBP group, the cerebral arteriovenous oxygen (AVO2) difference was 12.4 +/- 4.0 vol% before beginning the CPB, and it was 5.6 +/- 2.7, 5.7 +/- 3.1, 5.4 +/- 3.3, and 4.9 +/- 2.9 vol% at 10, 30, 60, and 90 min respectively after commencement of the PBP under hypothermic CPB. The cerebral AVO2 difference measured 10 min after commencement of the PBP was significantly less than that in the control group (P less than 0.05), but otherwise there were no significant differences between cerebral AVO2 differences in the two groups. Concentration of serum creatine kinase-BB (CK-BB) gradually increased in proportion to the duration of CPB in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Postischemic alterations of complex spike cell discharges and evoked potentials in rat hippocampal CA1 region.

Postischemic alterations of spontaneous discharges of complex spike cells (CS cells) and evoked potential in the rat hippocampal CA1 region were studied. Following 5 min of ischemia, CS cell discharge reappeared approximately 5 min after reperfusion and the frequency remained low, reaching a final value of 66.1 +/- 16.0% (n = 11) of preischemic frequency 2 h later. However, only one of 7 CS cells subjected to 20 min of ischemia exhibited discharges 2 h later. In the group with 5 min of ischemia, we obtained CS cell discharges from all rats at both 1 and 2 days after ischemia, with cluster frequencies indistinguishable from preischemic levels. In the group with 20 min of ischemia, discharges were noted in 7 neurons of 11 rats after 1 day, and in only 2 neurons of 8 rats after 2 days: their mean frequencies were lower than preischemic levels. In experiments of evoked potentials, the mean percentages of amplitudes of the post-synaptic potential (psp) 2 h after 3, 5 and 20 min of ischemia were 98.0 +/- 10.7 (n = 8), 70.7 +/- 8.22 (n = 9) and 45.1 +/- 6.34% (n = 7) of preischemic amplitudes, respectively. These results suggest that the functional deterioration of spike generation, as well as synaptic transmission, starts during transient ischemia and/or at the early stage of reperfusion.

Animals↗

PubMed1992

Fluorescent-labeled oligonucleotides that exhibit a measurable signal in the presence of complementary DNA.

Oligonucleotide derivatives with a fluorescent dye were designed for exhibiting a measurable signal only when they bind to complementary DNA in aqueous solution. The oligonucleotide with a dansyl group at the specific 2'-sugar residue was synthesized by using the protected 2'-dansylaminouridine phosphorobisamidite. The dansyl-oligonucleotide conjugate binds to its complementary DNA to form duplex with a normal stability and exhibits enhanced fluorescence together with a blue-shift in emission maxima after the hybridization. Another possible candidate involved the use of pyrene-excimer emission upon forming ternary complex between two pyrene-labeled oligonucleotide probes with target DNA. A new and general method for introduction of a pyrene fluorophore into the 3'- or 5'-terminal hydroxyl group of oligonucleotides via different linkers was developed.

DNA↗

PubMed1992

Sequence specific block of in vitro DNA synthesis with isopropyl phosphotriesters in template oligodeoxyribonucleotides.

We have synthesized four oligodeoxyribonucleotides each bearing an isopropyl phosphotriester at a defined position. These oligomers were used as templates for in vitro DNA synthesis catalyzed by Escherichia coli DNA polymerase I large fragment. Results showed that the phosphotriester inhibits the DNA chain elongation and the level of the inhibition is dependent on the base 5' to the phosphotriester.

Base Sequence↗

PubMed1991

Spontaneous rupture of the ascending aorta.

A case of spontaneous non-traumatic rupture of the thoracic aorta in a hypertensive patient is presented. The clinical findings suggested acute aortic dissection, and a large pericardial effusion was detected by echocardiography. The typical angiographic features of aortic dissection were not found. Autopsy revealed a longitudinal intimal tear and a rupture in the postero-lateral aspect of the ascending aorta. No false lumen was seen in the ascending aorta. When acute intrapericardial or intrapleural bleeding develops with no evidence of aortic aneurysm or dissection, spontaneous aortic rupture should be suspected.

Aged↗

PubMed1991

Primary anastomosis for acute ascending aortic dissection.

Intimal tear resection and primary anastomosis of the aorta were used for the treatment of eight patients with DeBakey I and II type acute aortic dissection. Five patients were of DeBakey I type, and three patients were of the II type. Moderate or severe aortic regurgitation (AR) was observed in six of eight patients. The site of the intimal tear was diagnosed by intraoperative echocardiography, and the adventitia corresponding to the intimal tear was transversely opened under total cardiopulmonary bypass. While resuspension of the aortic valve was performed on only one of six patients, AR disappeared in four, postoperatively. Two of eight patients died early postoperatively. The cause of death was postoperative cardiac tamponade in one patient and cerebral herniation in the remaining one. The other six patients have been observed for a mean period of 27 months. There is no late death, and they show no dilatation of the aortic root and deterioration of AR. We believe that this operative method is a simple and safe emergency procedure for DeBakey I and II type acute aortic dissection.

Acute Disease↗

PubMed1991

Synthesis of oligonucleotide derivatives with dansyl group at sugar fragment.

The method for introduction of dansyl group into the 2'-position of oligonucleotides is described. The dansyl group was introduced to 2'-position of uridine by the reaction of dansyl chloride with 2'-amino-2'-deoxyuridine, which was then converted to the 5'-dimethoxytrityl phosphorobisdiethylamidite derivative, (4). This reagent was used for the solid-phase synthesis of the oligonucleotide-dansyl conjugate, 5'-ACTCU(DNS)AGAGG. The conjugate could be purified by reversed-phase HPLC. The nucleoside composition of the conjugate was verified by the enzymatic digestion analysis.

Base Sequence↗

PubMed1991

Inhibition of DNA chain elongation by a phosphotriester linkage in template oligodeoxyribonucleotides.

We synthesized two oligodeoxyribonucleotides bearing an isopropyl phosphotriester at defined positions using new phosphorobisamidite chemistry. Diastereomers were separated with HPLC and their template properties were analyzed. Priming oligodeoxyribonucleotides labeled with 32P at the 5'-end were annealed to the modified oligodeoxyribonucleotides and elongated with DNA polymerase I large fragment from Escherichia coli. Results show that the phosphotriester inhibits the DNA chain elongation partially and the extents of the inhibition are remarkably different between the two diastereomers.

Base Sequence↗

PubMed1991

Oligonucleotides with bis-pyrene adduct in the backbone: syntheses and properties of intramolecular excimer forming probe.

2-(N-bis(2-pyrenylethyl)methyl-amino)ethanol (BPAE) was synthesized and its interaction with DNA was examined to explore the efficiency of intramolecular excimer forming probe. As a result the fluorescence of intramolecular excimer of BPAE disappeared with the addition of poly(dA)-poly(dT). This result suggests an unique type of probe with its introduction to oligonucleotide.

DNA↗

PubMed1991

[Coronary artery bypass grafting combined with operation for non-cardiac disease].

During the last two years and six months, ten patients underwent operation for both coronary artery disease and non-cardiac surgery. There were six patients with vascular disease, three with gastric cancer and one with cholelithiasis. Six patients had simultaneous operation of both coronary artery bypass grafting (CABG) and non-cardiac surgery, and four underwent non-cardiac surgery mean of 105 days after CABG. The number of significant lesions of coronary artery in patients with simultaneous or two-staged operation was 2.2 +/- 0.8 or 2.8 +/- 0.5 per patient, respectively. The operative time in patients with simultaneous operation was 361 +/- 49 minutes. However, in patients with staged operation the time for cardiac surgery was 380 +/- 36 minutes and the time for non-cardiac operation was 388 +/- 83 minutes. There were no patients with complications after either cardiac or non-cardiac operation. In patients having surgical indications for both coronary artery and non-cardiac diseases, CABG should be performed prior to the non-cardiac surgery. In patients with normal cardiac function and sufficient operative time after CABG, concomitant operation seemed to be recommended. In case with advanced malignant disease or incompetent cardiac function, staged operation would be selected for good surgical result.

Aortic Aneurysm↗

PubMed1991

[Surgical treatment of acute ascending dissection--a simplified operative method].

Primary anastomosis for acute ascending aortic dissection was performed in 8 patients. Primary anastomosis included resection of the intimal tear where applicable, a circumferential suture line in the ascending aorta at the site of the tear, and wrapping of the anastomosis of the ascending aorta with Dacron vascular prosthesis. The aortic valve was resuspended in 1 of 6 patients associated with aortic regurgitation. In 4 patients, aortic regurgitation disappeared postoperatively. Two patients show minor non-progressive valve regurgitation. Two of 8 patients died early postoperatively. There was no late death and dilatation of the aortic root in the follow-up period of mean 27 months. On the basis of these results, we believe that primary anastomosis is a simpler and safer operative method for acute dissection of the ascending aorta.

Acute Disease↗

PubMed1991

[Cardiovascular surgery in patients seventy years of age and older].

During 10 years between 1981 and 1990 surgical treatment was performed in 77 elderly patients (emergency 19) for cardiovascular disease at the 2nd Dept of Kurume Univ. Hospital. The 58 elective patients were studied. There were CABG in 29; valve replacement in 18; aneurysm operation in 11. The control patients were consisted of CABG in 60; valve replacement in 40; and aneurysm operation in 20 patients whose age were under 60 years. In the elderly group, operative mortality was 3 in 58 (5.2%) and there were no significant differences compared to that in the control patients. However, low output syndrome or respiratory complication was relatively prevented in the elderly patients and careful post operative management was required. The late results in the elderly patients NYHA or exercise tolerance was improved well. The 5 years actuarial survival rate was 93.3% in ischemic heart disease group, 87.7% in valvular heart disease group, and 90.0% in thoracic aneurysm group. No significant difference was seen compared to these results in control patients and no significant differences among these diseases.

Age Factors↗

PubMed1990

Postischemic alterations of spontaneous activities in rat hippocampal CA1 neurons.

Changes of spontaneous impulse discharges in rat hippocampal neurons during and after transient forebrain ischemia were investigated electrophysiologically. Spontaneous impulse frequencies of CA1 neurons before ischemia were varied from 0.4 to 20.0 impulses/s and its average was 5.8 +/- 1.2 (means +/- S.E., n = 36). These spontaneous discharges were completely suppressed during forebrain ischemia except for the transient hyperactivity observed just after the beginning of ischemia. Recovery of spontaneous discharges of CA1 neurons from suppression induced by 5 min ischemia started at 5 min, and neuronal activities were restored to pre-ischemic levels approximately 30 min after reperfusion. On the other hand, spontaneous impulse frequencies at all time points recorded after 20 min ischemia were less than 40% of the pre-ischemic levels. These continuous suppression of spontaneous activity after 20 min ischemia may suggest that neuronal function is impaired during and/or in the early stages of reperfusion, and functional disorders precede morphological degeneration.

Anesthesia↗

PubMed1990

A cytoplasmic determinant for dorsal axis formation in an early embryo of Xenopus laevis.

In Xenopus laevis, dorsal cells that arise at the future dorsal side of an early cleaving embryo have already acquired the ability to cause axis formation. Since the distribution of cytoplasmic components is markedly heterogeneous in an egg and embryo, it has been supposed that the dorsal cells are endowed with the activity to form axial structures by inheriting a unique cytoplasmic component or components localized in the dorsal region of an egg or embryo. However, there has been no direct evidence for this. To examine the activity of the cytoplasm of dorsal cells, we injected cytoplasm (dorsal cytoplasm) from dorsal vegetal cells of a Xenopus 16-cell embryo into ventral vegetal cells of a simultaneous recipient. The cytoplasm caused secondary axis formation in 42% of recipients. Histological examination revealed that well-developed secondary axes included notochord, as well as a neural tube and somites. However, injection of cytoplasm of ventral vegetal cells never caused secondary axis and most recipients became normal tailbud embryos. Furthermore, about two-thirds of ventral isolated halves injected with dorsal cytoplasm formed axial structures. These results show that dorsal, but not ventral, cytoplasm contains the component or components responsible for axis formation. This can be the first step towards identifying the molecular basis of dorsal axis formation.

Animals↗

PubMed1990

Oligonucleotides with pyrene fluorophore at the sugar fragment: synthesis and properties in binding to complementary polynucleotide.

Oligonucleotides with 1-pyrenylmethyl substituent at the designated sugar residue were synthesized by using 5'-dimethoxytrityl 2'-(1-pyrenylmethyl)uridine 3'-phosphorobisdiethylamidite 1. It was shown that the pyrene-oligonucleotides have enhanced affinity in binding to the complementary polynucleotide sequence. The fluorescence yield and life time of the pyrene-oligonucleotide was drastically enhanced when bound by the complementary polynucleotide.

Base Sequence↗

PubMed1990

Structure and properties of oligonucleotide analogs having phosphoramidate linkages.

The oligothymidylate analogs, having several stereo regular phosphoramidate linkages, were synthesized. Melting temperatures(Tm) of complexes of the analogs and poly(dA) were measured by spectroscopic method. The abilities of the analogs to form the complexes with poly(dA) depended on their P-chirality of their modified linkages: one of the chiral isomers formed stable complexes, but another isomer formed less stable complexes.

Amides↗

PubMed1990

[Combined operation for renovascular hypertension and ischemic heart disease].

We have experienced two patients of ischemic heart disease associated with renovascular hypertension. Patient 1 (60-year-old man) underwent LV aneurysmectomy and triple aortocoronary bypass grafting (saphenous vein to diagonal branch, left internal mammary artery to obtuse marginal branch, and right gastroepiploic artery to right coronary artery). Seventy five days after the initial cardiac surgery endarterectomy for the left renal artery and bifurcated Dacron graft implantation for the iliac artery obstruction were performed. Patient 2 (62-year-old woman) underwent simultaneous operation of both right nephrectomy and triple aortocoronary bypass grafting (saphenous vein grafts to obtuse marginal branch and right coronary artery, and left internal mammary artery to left anterior descending artery). Their postoperative courses were uneventful except unstable and high blood pressure for four to seven days after the operation. It appears that it should be decided to achieve either simultaneous or two stage approach for ischemic heart disease associated with renovascular hypertension based on the preoperative cardiac function. And both postoperative cardiac function and hypertension should be carefully managed until the blood pressure becomes stable after the surgery.

Coronary Artery Bypass↗

PubMed1990

[Arterial thrombosis associated with Crohn's disease: a case report].

In the English literature, only 27 cases of arterial thrombosis associated with Crohn's disease have been described. The present case appears to be the first reported case in the Japanese literature. A 43-year-old man was treated for intestinal obstruction caused by Crohn's disease and complicated by superior mesenteric vein thrombosis by surgical resection of 150cm of small bowel in June 1981. In March 1983, the right external iliac artery had become occluded and part of the left external iliac artery had assumed an irregular shape and the right ilio-femoral bypass surgery using PTFE was carried out. Three months later occlusive ileus reoccurred and angiograms showed that the superior mesenteric and right hepatic arteries had 30% and 20% stenosis respectively. Small bowel in 50cm in length was resected with subsequent administration of salicylazosulfapyridine at a dose of 3g per day. There was no reappearance of bowel symptoms. The patient again complained of numbness in the right leg in February 1988 and a left external iliac-right common femoral crossover bypass operation was carried out using a ringed 8mm Dacron graft. Intraoperatively, it was found that the left external iliac and the right common femoral arteries had intimal thickening but no atherosclerosis.

Adult↗