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Biomedical subjects

K Yasuda

Publications and source records attributed to K Yasuda.

At least 559 records · Page 31Linked to original sources
PubMed1996

[Comparison of the protective prorerties of St. Thomas', Tyers', and Bretschneider's cardioplegic solutions in the neonatal rabbit heart].

Many studies suggest that single-dose and multidose cardioplegia are protective in the ischemic adult heart, but in the neonatal heart single-dose cardioplegia is only protective, whereas multidose cardioplegia is damaging. We examined three clinically used cardioplegic solutions to compare the protective properties of single-dose and multidose cardioplegia in the neonatal rabbit heart (aged 7 to 10 days). The clinical solution studied were St. Thomas', Typers' and Bretschneider's solutions. In isolated working hearts (n = 8/group), cardiac function was assessed prior to 10 hours of ischemia (20 degrees C) and again after 35 min reperfusion (15 min Langendorff, 20 min working). All hearts received a pre-ischemic infusion (10 ml) of cardioplegic solution. The cardioplegic solution was given either as a single infusion (single-dose) or as repeated infusions (multidose) with 5 ml of cardioplegic solution every hour. The changes in coronary vascular resistance (CVR) during repeated cardioplegic infusions were measured in the multidose groups. During 15 min of Langendorff reperfusion, creatine kinase (CK) leakage and CVR were evaluated in all hearts. The results revealed that single-dose cardioplegia provided significantly better functional recovery than multidose cardioplegia in hearts given St. Thomas' or Tyers' solutions, while using Bretschneider solution single-dose cardioplegia Tended to provide better functional recovery. Post-ischemic CK leakages were higher in hearts given Bretschneider's solution in both single-dose and multidose cardioplegia. In hearts given St. Thomas' and Tyers' solutions, post-ischemic CVR in the single-dose group is lower than that in the multidose group, whereas post-ischemic CVR was lowest in the multidose group using Bretschneider's solution. Among multidose groups, CVR prior to reperfusion was lowest in Breschneider's solution as well. In conclusions, these results confirmed that, using the clinical solutions studied, single-dose cardioplegia provided better functional recovery than multidose cardioplegia in the neonatal rabbit heart. However, low CVR in Bretschenider's multidose cardioplegia suggested the better protection in coronary vasculature although functional recovery was poor.

Animals↗
PubMed1996

[Subtotal aortic replacement in a patient with Marfan's syndrome--replacement of the ascending aorta and entire aortic arch for acute type I aortic dissection 4 years after the thoracoabdominal replacement].

We report a patient with Marfan's syndrome who underwent replacement of the ascending aorta and the entire aortic arch for acute type I aortic dissection 4 years after the thoracoabdominal replacement. As a result, she underwent subtotal aortic replacement from the ascending aorta to the bilateral common iliac arteries in three stages. A 48-years-old female was admitted to our service because of acute heart failure and cardiogenic shock caused by acute DeBakey type I aortic dissection. She had undergone replacement of the descending thoracic aorta at the age of 44 and replacement of the remaining thoracoabdominal aorta with reimplantation of the four major abdominal branches at the age of 46 for a chronic expanding DeBakey type IIIb dissecting aneurysm. She successfully underwent replacement of the ascending aorta and the entire aortic arch with an aortic prosthesis provided with four branch grafts for reconstruction of the arch vessels. Considering the high incidence of new aortic lesion, extensive aortic replacement and careful postoperative follow-up are necessary in patients with Marfan's syndrome.

Aortic Dissection↗
PubMed1996

[Successful surgical repair of acute DeBakey type I aortic dissection complicated by acute occlusion of the suprarenal abdominal aorta].

We reported a case of acute DeBakey type I aortic dissection presented with occlusion of the suprarenal abdominal aorta, who was successfully treated by simultaneous graft replacement of the ascending aorta and total aortic arch. The patient was a 68-year-old man who complained of chest pain and symptoms of acute arterial occlusion of bilateral lower extremities, and who had consciousness disturbance due to stroke caused by aortic dissection. He underwent simultaneous graft replacement of the ascending aorta and total aortic arch under selective cerebral perfusion during an emergent operation. For reconstruction of the arch vessels, we used three separate grafts that were connected to the aortic prosthesis before use. Although postoperative course was complicated by myonephropathic metabolic syndrome, the patient subsequently recovered and was discharged on foot. Early vascular reconstruction and appropriate management of reperfusion injury are extremely important in the setting of malperfusion phenomena complicating acute aortic dissection.

Aged↗
PubMed1996

[Evolution and recent trends in patient selection and reconstruction method for chronic aortic dissection].

Evolution and recent trends in patient selection and reconstruction method for chronic aortic dissection are reported. Although patient selection and reconstruction method for chronic type A aortic dissection are essentially identical with those for acute type A aortic dissection, chronic dissection frequently necessitates extended reconstruction of the aortic arch. Aortic valve-sparing operation is increasingly applied for associated aortic regurgitation. In chronic type B aortic dissection, operation is indicated when the diameter exceeds 5 cm, if it is symptomatic (i.e. those accompanied with pain or malperfusion of the vital organ), or when it is enlarging rapidly. Operative treatment includes resection of the intimal tear and replacement of the dilated segment. With the advance in diagnosis, methods of organ protection and operative techniques, operative results for chronic aortic dissection had been improving, despite the fact that these complex lesion frequently requires extensive aortic reconstruction with reimplantation of the major aortic branches. Spinal cord protection in extensive thoracoabdominal reconstruction for type B aortic dissection remains an unsolved problem.

Aortic Dissection↗
PubMed1995

Pancreatic beta-cell-specific targeted disruption of glucokinase gene. Diabetes mellitus due to defective insulin secretion to glucose.

Mice carrying a null mutation in the glucokinase (GK) gene in pancreatic beta-cells, but not in the liver, were generated by disrupting the beta-cell-specific exon. Heterozygous mutant mice showed early-onset mild diabetes due to impaired insulin-secretory response to glucose. Homozygotes showed severe diabetes shortly after birth and died within a week. GK-deficient islets isolated from homozygotes showed defective insulin secretion in response to glucose, while they responded to other secretagogues: almost normally to arginine and to some extent to sulfonylureas. These data provide the first direct proof that GK serves as a glucose sensor molecule for insulin secretion and plays a pivotal role in glucose homeostasis. GK-deficient mice serve as an animal model of the insulin-secretory defect in human non-insulin-dependent diabetes mellitus.

Alternative Splicing↗
PubMed1995

Cloning and expression of murine high molecular mass heat shock proteins, HSP105.

We have shown that the 105-kDa heat shock protein (HSP105) and the 42 degrees C-specific heat shock protein (42 degrees C-HSP) constitute high molecular mass heat shock proteins. To elucidate the structure of these heat shock proteins, we have screened a cDNA library constructed with poly(A)+ RNA derived from mouse FM3A cells preheated at 42 degrees C for 2 h using an antibody against murine HSP105. Two full-length cDNA clones were obtained: the pB105-1 insert encoded an 858-amino acid protein, and the pB105-2 insert encoded an 814-amino acid protein and lacked 44 amino acids found in pB105-1. The two clones contained the amino acid sequence found in the 17-kDa polypeptide fragments from HSP105 and 42 degrees C-HSP by lysylendopeptidase digestion. In vitro translation products of the RNA transcripts from pB105-1 and pB105-2 migrated to the same positions of HSP105 and 42 degrees C-HSP, respectively, on SDS-polyacrylamide gel electrophoresis. Northern blot analysis showed that the transcript was approximately 4 kilobases in murine FM3A cells and was strongly induced by heat shock and by treatment with arsenite or an amino acid analog. By reverse transcription-polymerase chain reaction analysis using primers by which deletion of 132 nucleotides in pB105-2 could be detected, the polymerase chain reaction product corresponding to pB105-2 was increased only after heat shock at 42 degrees C, whereas the product corresponding to pB105-1 was induced by heat shock at either 42 or 45 degrees C and also by other stresses. Thus, the cDNA clones pB105-1 and pB105-2 encode HSP105 and 42 degrees C-HSP, respectively, and HSP105 and 42 degrees C-HSP (a short form of HSP105) are suggested to be produced by alternative splicing. Here, HSP105 and 42 degrees C-HSP are renamed HSP105 alpha and HSP105 beta, respectively. A protein sequence homology search revealed that HSP105 shares 54, 34, and 25% amino acid identity with human HSP70RY, the sea urchin egg receptor for sperm, and murine inducible HSP70, respectively. Furthermore, by Northern blot analysis, HSP105 mRNA was revealed to be present in most murine tissues and to be highly expressed in the brain.

Amino Acid Sequence↗
PubMed1995

Localization, trafficking, and temperature-dependence of the Aequorea green fluorescent protein in cultured vertebrate cells.

The localization, trafficking, and fluorescence of Aequorea green fluorescent protein (GFP) in cultured vertebrate cells transiently transfected with GFP cDNA were studied. Fluorescence of GFP in UV light was found to be strongest when cells were incubated at 30 degrees C but was barely visible at an incubation temperature of 37 degrees C. COS-1 cells, primary chicken embryonic retina cells, and carp epithelial cells were fluorescently labeled under these conditions. GFP was distributed uniformly throughout the cytoplasm and nucleus independent of cell type examined. When GFP was fused to PML protooncogene product, fluorescence was detected in a unique nuclear organelle pattern indistinguishable from that of PML protein, showing the potential use of GFP as a fluorescent tag. To analyze both function and intracellular trafficking of proteins fused to GFP, a GFP-human glucocorticoid receptor fusion construct was prepared. The GFP-human glucocorticoid receptor efficiently transactivated the mouse mammary tumor virus promoter in response to dexamethasone at 30 degrees C but not at 37 degrees C, indicating that temperature is important, even for function of the GFP fusion protein. The dexamethasone-induced translocation of GFP-human glucocorticoid receptor from cytoplasm to nucleus was complete within 15 min; the translocation could be monitored in a single living cell in real time.

Amino Acid Sequence↗
PubMed1995

The location of the paths subserving micturition: studies in patients with cervical myelopathy.

Urodynamic studies and neurological examinations were performed on 128 patients with cervical myelopathies including 82 with spondylitic myelopathy and 46 with ossification of the posterior longitudinal ligament (OPLL), investigating the location of the paths subserving micturition in the spinal cord. Accurate history taking revealed micturitional symptoms in 95 patients, including irritative symptoms in 61 and obstructive symptoms in 71. Urinary incontinence was noted in 25 and residual urine of over 100 ml or retention was found in 22. Neurological examination revealed disturbed deep sensation in 55, disturbed superficial sensation in 63 and pyramidal signs (weakness, hyperreflexia of legs and Babinski sign) in 96 patients. Urodynamic studies revealed uninhibited contraction in 61 and detrusor-sphincter dyssynergia in 22 patients. Bladder capacity was smaller in patients with Babinski sign (P < 0.05) and in patients with uninhibited contraction (P < 0.001). Uninhibited contraction was more frequent in patients with all three of the above-mentioned pyramidal signs (P < 0.05). Detrusor-sphincter dyssynergia was more frequent in patients with disturbed deep sensation (P < 0.05) and pyramidal signs (P < 0.05, P < 0.0005). From above results and our previous findings in patients with anterior spinal artery syndrome and with tabes dorsalis, it is concluded that the pathway subserving detrusor function seems to be located mainly in the lateral column of the spinal cord. The descending pathway subserving coordination of bladder and urethral sphincter seems to be located mainly in the lateral column, and its ascending pathway seems to be located in the dorsal column. The path subserving urinary sensation seems to be located mainly in the dorsal column of the spinal cord.

Adult↗