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Biomedical subjects

K Miyahara

Publications and source records attributed to K Miyahara.

At least 91 records · Page 5Linked to original sources
PubMed1996

Human group II phospholipase A2 in normal and diseased intervertebral discs.

We measured calcium-dependent phospholipase A2 (PLA2) activity and immunoreactive group II PLA2 levels of 54 normal discs obtained from cadavers and 73 disc samples surgically obtained from patients with spinal disorders, including intervertebral disc herniations, spondylosis, and spondylolisthesis. Both cadaveric and surgical disc specimens contained about two-fold greater PLA2 activity than the ileal mucosa, one of the richest sources of group II PLA2. Discs of middle-aged cases had significantly higher activity than those of younger and elder cases. In cadaveric normal discs, calcium-dependent PLA2 activity was significantly higher in females than in males. Annulus fibrosus and nucleus pulposus contained the same PLA2 levels. In diseased disc, herniated fragments that had extruded or protruded out of the discs possessed lower activity than other parts of discs in the intervertebral space. Immunoreactive group II PLA2 levels of intervertebral discs closely correlated with PLA2 enzymatic activity. We purified a PLA2 from human intervertebral disc to homogeneity to further identify the isozymic nature of discal PLA2. Its NH2-terminal amino acid sequences and molecular weight were identical to those of human group II PLA2. Immunohistochemical analysis using a monoclonal anti-group II PLA2 antibody showed that in both annulus fibrosus and nucleus pulposus chondrocytes contained intense group II PLA2 immunoreactivity in their cytoplasm, and that the matrix contained no substantial immunoreactivity. These results suggest that group II PLA2 in chondrocytes has important physiological roles in discal ordinary metabolism, maintaining discal homeostasis.

Adolescent↗
PubMed1996

yAP-1- and yAP-2-mediated, heat shock-induced transcriptional activation of the multidrug resistance ABC transporter genes in Saccharomyces cerevisiae.

We have examined whether the stress-induced transcriptional activation of YDR1/PDR5/STS1 is mediated by yAP-1 and yAP-2. Of the stresses examined, heat shock-induced, rapid and transient PDR5 expression became very low in a yap1 yap2 double-gene disruptant, indicating that the yAP proteins mediate the response. Similar results were obtained with SNQ2, a close homologue of PDR5. A set of 5'-truncation derivatives of the PDR5 gene identified the region from -484 to -434 as being sufficient for the response. A sequence similar to the yAP-1 recognition element recently identified in the stress-responsive yeast genes was found in this region and in the 5'-flanking sequences of SNQ2.

ATP-Binding Cassette Transporters↗
PubMed1996

Massive endobronchial hemorrhage after pulmonary embolectomy.

Massive endobronchial hemorrhage is a lethal complication in pulmonary embolectomy. We report a case of massive endobronchial hemorrhage occurring after successful restoration of pulmonary blood flow using cardiopulmonary bypass in a patient with pulmonary embolism. Two possible causative factors of this complication are described.

Adult↗
PubMed1996

Antifungal activity from Alpinia galanga and the competition for incorporation of unsaturated fatty acids in cell growth.

An antimicrobial diterpene was isolated from Alpinia galanga in the screening for potentiators of phytochemical antibiotic action. The structure was elucidated by spectral data and identified as (E)-8 beta, 17-epoxylabd-12-ene-15, 16-dial (1). Diterpene 1 synergistically enhanced the antifungal activity of quercetin and chalcone against Candida albicans. Antifungal activity of 1 was reversed by unsaturated fatty acids. Protoplasts of C. albicans were lysed by 1. These results suggest that antifungal activity of 1 is due to a change of membrane permeability arising from membrane lipid alternation.

Antifungal Agents↗
PubMed1996

Zwitterionic digalactosylceramides from the earthworm, Pheretima asiatica.

Nine homogeneous glycosphingolipids were isolated from the earthworm, Pheretima asiatica (Annelida). All of them are digalactosylceramides carrying a choline phosphate group in the outer galactose moiety. Their full structures including the position of a phosphocholine unit were determined based on chemical and spectral evidence.

Acetylation↗
PubMed1996

Six trigalactosylceramides from the leech (Hirudo nipponica).

Six neutral glycosphingolipids were isolated in the pure state from the leech, Hirudo nipponica (Annelida). In contrast to the zwitterionic monogalactosylceramides carrying a choline phosphate group so far obtained, all compounds are non-zwitterionic glycosphingolipids, trigalactosylceramides. Five compounds possess a Ga1 alpha 1-6Ga1 alpha 1-6Ga1 beta 1-Cer core, and one is unique in having a Ga1 alpha 1-6Ga1 beta 1-Cer structure. Their full structures have been determined on the bases of chemical and spectral evidence.

Animals↗
PubMed1996

Relationship between intracoronary thrombolysis and fibrino-coagulation--special reference to TAT/PIC and FPA/PIC.

To clarify the relationship between the results of intracoronary thrombolytic therapy (ICT) and fibrino-coagulation in patients with acute myocardial infarction (AMI), the thrombin-antithrombin III complex (TAT) and fibrinopeptide A (FPA), as indices of accelerated coagulation, and the plasmin- alpha 2-plasmin inhibitor complex (PIC), as an index of accelerated fibrinolysis in peripheral blood, were measured just before and after heparin injection (5,000 U), and immediately after ICT. Twenty-four patients with AMI were divided into 2 groups according to the results of ICT; successful ICT (group S) and unsuccessful ICT (group F). As a control group (group C), 14 age-matched normal volunteers were also studied. The levels of TAT and FPA before ICT were significantly higher in groups S and F than in group C (p < 0.01). The TAT level before ICT in group F was higher than that in group S (p = 0.07), however, the TAT, FPA and PIC levels showed no significant differences between groups S and F at each sampling time. TAT/PIC before ICT was significantly higher in group F than in group S (F: 0.026 +/- 0.020 vs S: 0.008 +/- 0.004, p < 0.05), whereas there was no remarkable difference in FPA/PIC between groups S and F. These results indicate that hyper-coagulation had occurred in the AMI cases and that coagulation had been more accelerated in group F. TAT/PIC might be an index of the equilibrium of the fibrino-coagulating system. Therefore, TAT/PIC measurement before thrombolytic therapy may be more useful than TAT measurement alone for evaluating recanalization in ICT.

Aged↗
PubMed1996

Effect of inferior vena cava occlusion on left ventricular end-systolic pressure-volume relations in intact canine hearts--modulation by the autonomic nervous system.

The effect of inferior vena cava occlusion (IVCO) on end-systolic pressure-volume relations (ESPVR) of the left ventricle was studied in intact canine hearts. In 12 anesthetized open-chest dogs, left ventricular (LV) pressure and volume were measured simultaneously using a microtip catheter and a conductance catheter, respectively. ESPVR was constructed from LV pressure-volume loops during IVCO (10 sec) and subsequent IVCO release under 5 conditions: control, after righ or left cardiac sympathetic nerve (CSN) stimulation, bilateral vagotomy (VAT), and both VAT and bilateral CSN resection. Emax in IVCO release was significantly greater than that in IVCO in the control state. Following right or left CSN stimulation, Emax was increased increased in both IVCO and IVCO release, with the same hysteretic change in Emax. With VAT, however, no hysteretic change was observed because Emax was the same in IVCO and IVCO release. After VAT and CSN resection, Emax was decreased in both IVCO and IVCO release, and again no hysteretic change was observed. These data imply that a sudden decrease in venous return into the heart induces a decrease in afferent vagal nerve activity, and thus increases efferent CSN activity, resulting in enhanced myocardial contractility.

Animals↗
PubMed1996

Chaotic musical murmur in aortic regurgitation.

We report an interesting case of aortic regurgitation. Phonocardiographically, the shape of the diastolic musical murmur in this case changed in each cardiac cycle despite being in sinus rhythm, in the same posture and in the same breathing phase. Experimentally, we were able to obtain a similar noise pattern using an artificial respirator and a hemispherical silicone membrane. We concluded that the irregular and chaotic change in the shape of the diastolic musical murmur in the present case occurred due to irregular swaying of the non-coronary cusp under the influence of the Venturi effect owing to a regurgitant jet stream.

Aortic Valve↗
PubMed1996

Contrast-enhanced MRI with gadodiamide injection in rat disease models.

The present study was designed to confirm the usefulness of contrast-enhanced magnetic resonance imaging (MRI) in diagnosing strokes of stroke-prone spontaneously hypertensive rats (SHRSP) and middle cerebral artery (MCA) occlusion, hepatocellular carcinoma and hydronephrosis of each experimental rat model. Male Sprague-Dawley rats (250-500 g), male SHRSP (ca. 250 g) and male F344 rats (ca. 300 g) were used for the investigation. Gadodiamide injection (Omniscan, Daiichi Pharmaceutical Co., Ltd. and Nycomed AS, Norway) was administered intravenously as the contrast agent at a dose of 0.1 mmol/kg except in hydronephrosis, where a dose of 0.05 mmol/kg was used. Magnetic resonance (MR) images were obtained with a 1.5T or a 2.0T magnetic field strength MRI unit. The signal intensity of the stroke lesions was increased after administration of gadodiamide injection in SHRSP and MCA-occluded rats. Hepatocellular carcinoma was undetectable without the use of the contrast agent, but the signal intensity of the tumor increased after administration of the gadodiamide injection, allowing the lesions to be detected. The signal intensity of the renal medulla increased in the non-ligated kidney, but not in the hydronephrotic kidney. The information given by the post-contrast images were superior to those obtained from the pre-contrast images in all the models. Contrast effects in SHRSP and MCA-occluded rats were related to differences in capillary permeability, those in rats with hepatocellular carcinoma depended on differences in vascularity, and those in hydronephrotic rats depended on blood flow and permeability.

Animals↗
PubMed1996

Contrast-enhanced MRI with gadodiamide injection in rabbit carcinoma models.

This study was designed to demonstrate the broad utility of contrast-enhanced magnetic resonance imaging (MRI) for diagnosis of carcinoma. Twenty-six New Zealand White rabbits of either sex (1.7-3.4 kg) were used for the investigation. VX2 carcinoma (squamous cell carcinoma) was implanted in either the brain, lung, ovary, bone or muscle of rabbits. Contrast agent, Gadodiamide Injection, was administered intravenously at a dose of 0.1 mmol/kg. MR images were obtained by a 1.5 T, or a 2.0 T magnetic field strength super-conductive MRI unit. The intensity of the signal for the carcinoma was increased after administration of contrast agent, and the detectability or diagnostic information of post-contrast images was superior to that of pre-contrast images in all models. In addition, no significant side effects were observed during the MRI examination. After diagnosis using MRI, morphological damage in each model was assessed by gross and histopathological examinations. In contrast-enhanced MRI, though there were variations between the models employed, contrast effects in brain and muscle carcinoma models were generally related to differences in capillary permeability, while imaging in lung, ovary and bone carcinoma models was dependent on differences in blood flow rate and the size of interstitial spaces. Overall, our results demonstrate that contrast-enhanced MRI is a useful and safe method for diagnosing tumors.

Animals↗
PubMed1996

Tensile force of pacing lead extraction. A comparison between tined type and screw-in type.

Three months after implantation of endocardial pacing leads in 10 mongrel dogs, the tensile forces needed to remove 5 tined type and 5 screw-in type leads were compared experimentally. Mean maximum tensile force was 291 +/- 174 g with the screw-in type and 1174 +/- 369 g with the tined type (p < 0.01). Histopathologically, no changes suggesting any myocardial damage due to lead extraction were recognized in cases where screw-in type leads were used. These results support the clinical feasibility of safe and easy manual retraction of infected pacing leads of the screw-in type.

Animals↗
PubMed1996

Smooth muscle cell proliferation in the arterial intima after stretch injury: relationship between the severity of stretching and intima hyperplasia in New Zealand white rabbits.

We examined histologically whether the severity of arterial stretch injury is related to the degree of subsequent intimal hyperplasia. In six male New Zealand White rabbits, the common carotid artery was hyperextended with a 3F Fogarty balloon catheter. Two weeks later, no proliferative change was evident in the intima in the most hyperextended portion. Paradoxically, however, intimal hyperplasia due to smooth muscle cell proliferation was observed in the moderately extended portions. The intimal hyperplasia appeared to be exacerbated where the arterial stretching was more severe. It is concluded that the severity of arterial stretch injury is closely related to the intimal proliferation of smooth muscle cells.

Animals↗
PubMed1996

Sudden death during Holter electrocardiogram monitoring in a patient with variant angina.

We report a case of sudden death due to variant angina during Holter electrocardiogram (ECG) monitoring. The patient, a 60-year-old man, had been aware of chest discomfort lasting less than one minute at midnight 2 days earlier. Because variant angina or arrhythmia was suspected, Holter ECG monitoring was performed. The patient spent a whole day without a recurrence of chest pain before going to bed, but at midnight he developed sudden chest pain, and died immediately after taking a sublingual tablet of isosorbide-dinitrite. Analysis of the Holter ECG revealed ventricular fibrillation after several ventricular premature beats following ST-segment elevation in both the CM5 and NASA leads. This case shows that sudden death from variant angina may occur within a few days after the first onset, and also highlights whether priority should be given to making a definite diagnosis or giving treatment when variant angina is strongly suspected.

Angina Pectoris, Variant↗
PubMed1996

Effects of propionate and ammonium on contractions produced by sodium removal in human internal mammary artery and saphenous vein.

Effects of propionate and ammonium on contractions produced by Na+ removal (0-Na+ contraction, replaced with N-methyl-D-glucamine) were studied and compared with those produced by 60 mM K+ in muscle strips isolated from human internal mammary artery (IMA) and saphenous vein (SV), clinically used as bypass vessels. Contractions induced by 60 mM K+ (60-K+ contractions) were similar in both vessels. 0-Na+ contraction was significantly larger in the vein than in the artery. Neither 60-K+ nor 0-Na+ contractions were significantly affected by NG-nitro-L-arginine (30 microM) or phenoxybenzamine (1 microM). Ouabain (2 microM) slowly potentiated 0-Na+ contractions and the 3rd contraction produced 60 min after ouabain application was 291 +/- 36% in the artery and 184 +/- 41% of the control (n = 10) in the vein. Propionate (20 mM) potentiated 60-K+ contraction more strongly in the vein than in the artery, but potentiation of 0-Na+ contraction was greater in the artery than in the vein. On the other hand, ammonium (20 mM) inhibited 60-K+ contractions more strongly in the artery than the vein, whereas inhibition of 0-Na+ contraction was stronger in the vein. 0-Na+ contraction is likely to be produced by an Na(+)-Ca2+ exchange mechanism, and the effects of propionate and ammonium are considered to be mediated by intracellular acidification and alkalinization, respectively. It is speculated that an Na(+)-H+ exchange may also be involved in 0-Na+ contraction and that SV has slightly lower pHi than IMA.

Adult↗
PubMed1996

[Case report of David's operation for annuloaortic ectasia and aortic regurgitation in a Marfan patient].

We report a 35-year-old Marfan patient who underwent David's operation for annuloaortic ectasia and aortic regurgitation. This new technique is done by excising the aneurysmal portion of the ascending aorta and sinuses of Valsalva but by leaving the aortic valve leaflets and some aortic wall attached to the left ventricular outflow tract inside the Dacron tube. Postoperative echocardiography revealed well coapted aortic valve leaflets and a very small amount of regurgitation. A rigid aortic route without sinuses of Valsalva may increase the mechanical stress on the leaflets and shorten their durability but this procedure have the advantage of so called Bentall's operation by preserving the native aortic valve.

Adult↗
PubMed1996

[Influence of recirculation type blood cardioplegia on perfusion pressure in open heart surgery].

Infusion blood cardioplegia often decreases the perfusion pressure during open heart surgery. The blood level of bradykinin (BK) was measured in both the cardiopulmonary bypass (CPB) and blood cardioplegia circuit. Infusion cardioplegia with recirculation type circuit increased the BK level of cardioplegia and the perfusion pressure decreased abruptly with the increase BK level in the CPB circuit. In the case of single pass type circuit the BK level was not increased either in cardioplegia or CPB and perfusion pressure was not decreased. We concluded that the single pass type of cardioplegia circuit is superior to the recirculation type because of less production of BK.

Aged↗