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Biomedical subjects

T Asakura

Publications and source records attributed to T Asakura.

At least 181 records · Page 10Linked to original sources
PubMed1994

[Thrombolytic therapy of thrombosed Björk-Shiley aortic valve prosthesis--report of four cases].

Prosthetic valve thrombosis is associated with high mortality. Thrombolytic therapy is a promising alternative to valve replacement in the management of prosthetic valve thrombosis. To determine the efficacy and safety of thrombolytic therapy for thrombosed Björk-Shiley aortic valve prosthesis, 4 patients who received urokinase intravenously for this disorder were analyzed. In 3 patients, the successful outcome was sustained in that they remained asymptomatic and did not require operative intervention during follow-up, which ranged from 17 to 101 months. In one patient clinical signs of mild congestive heart failure occurred. This patient was surgically treated by thrombectomy and debridement of the prosthetic valve. Failure of urokinase treatment to resolve the thrombus after 1 week indicates that tissue overgrowth or fibrous, organized thrombus is the cause of prosthetic malfunction. Surgical intervention for this problem should be considered only after thrombolytic therapy has been tried and has failed. Our experience with urokinase treatment of thrombosis of aortic Björk-shiley prostheses indicates that this form of treatment should always be applied before surgical intervention. We also attempted to define the optimum protocol of fibrinolytic therapy by clinical evaluation. A protocol for the safe treatment of thrombosed valve is urokinase in initially administered in the doses as 960,000 units for 24 hours, then followed by a maintenance infusion at the half dose every 24 or 48 hours later. Thrombolytic therapy should be continued for 1 week at least to prevent rethrombosis even normalization of valve function was documented clinically. Simultaneous heparin infusion of 10,000 units for 24 hours is then started to replaced by warfarin treatment adjusted to obtain optimal prothrombin times.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[Early repair of postinfarction ventricular septal perforation: a case report of an improved surgical technique].

Accurate repair of postinfarction ventricular septal perforation (VSP) has mainly depended on the technique for friable septal reinforcement. Modified closure of VSP with Xenomedica patch was performed in 63-year-old male. Friable border of the septum was successfully sandwiched between horse-shoe shape prejett (right side) and main patch (left side). The advantages of this modified surgical procedure are as follows: (1) septum can be seen through horse-shoe shape patch (even when tying the mattress sutures; (2) Xenomedica patch is flexible enough for avoiding the cutting for friable septum, and is strong enough for sandwiching the septum.

Heart Rupture, Post-Infarction↗
PubMed1994

[Clinical experience and early results of aortic valve replacements with Medtronic Hall 20 A].

We experienced aortic valve replacement for 18 patients (4 male and 14 female, ranging from 40 to 81 years old, mean 64 years old) with small aortic annulus with new small prosthesis. Medtronic Hall 20 A (MH 20 A). The average body surface area was 1.47 m2 (range 1.28 to 1.81 m2). One patient was died of lung cancer at 3 months postoperatively. One nonstructural dysfunction and one low cardiac output syndrome was noted during operation. Sixteen survivors with MH 20 A, showed satisfactory clinical results, except for minor thromboembolism, in 2 patients. The MH 20 A had the same function as that of MH 21 A, already reported. We concluded that aortic valve replacement by Medtronic Hall 20 A prosthesis was usefull for the patient with small aortic annulus.

Adult↗
PubMed1994

[Pre-operative autologous blood collection in neurosurgical patients].

Homologous transfusion has been known to cause viral infections and other complications. Recently, autologous transfusion has been adopted widely as a safer and more effective procedure to prevent these complications. The authors report the experiences of 29 patients who had been operated on after preparation of autologous blood. Furthermore, the authors report a study concerning maximum surgical blood order schedule (MSBOS) of these operations. 212 patients operated on between January, 1991 and June, 1993 were used for this study of MSBOS. Although intraoperative transfusion was performed on 14 of 29 patients, the need for homologous transfusion was avoided in 12 of these 14 patients by the use of autologous blood. The frequency of homologous transfusion was reduced significantly after the introduction of pre-operative autologous blood collection in our clinic. The patients' value of hemoglobin fell after the collection of blood but these levels were not so seriously low as to impede the performance of operations. 212 cases of operated patients were divided according to the operative methods and diagnosis for calculation of MSBOS. The results were as follows; Craniotomy and removal of glioma 5u, meningioma 11u, neurinoma 7u, AVM 5u, transsphenoidal surgery 3u, Moyamoya disease 2u and V-P or S-P shunt 0u. Pre-operative autologous blood collection is easy to achieve for scheduled neurosurgical operations, and autologous transfusion is a beneficial procedure which should be used more widely.

Blood Loss, Surgical↗
PubMed1994

[A case of ruptured aneurysm associated with persistent primitive trigeminal artery and metopism].

The authors reported an extremely rare case of ruptured aneurysm associated with persistent primitive trigeminal artery (PTA) and persistent metopic suture (metopism). A 46-year-old female suffered sudden onset of a severe headache with nausea and vomiting on February 24, 1991. She was transferred to Kagoshima Prefectural Oshima hospital from the other clinic on the next day. She complained only of severe headache on admission, and neurological examination revealed no abnormal findings. Plain craniograms disclosed a persistent metopic suture extending from the bregma to the midportion of the frontal bone. Computed tomography demonstrated a mild subarachnoid hemorrhage. The right internal carotid angiograms showed a ruptured aneurysm in the middle cerebral artery. These angiograms also demonstrated PTA originating from the cavernous portion of the internal carotid artery and ending at the mid-portion of the basilar artery. The frequency of angiographic demonstration of persistent primitive trigeminal artery is 0.1 to 0.3%. It is well recognized that approximately 14% of patients with PTA also have intracranial aneurysm. The incidence of persistent metopic suture in adults is 1-10%. After an extensive review of the literature we have concluded that there has been no case report of a ruptured aneurysm associated with PTA and metopism. The authors think that, in this case, the coexistence may be only incidental.

Aneurysm, Ruptured↗
PubMed1994

Resection of aortic aneurysms without aortic clamp technique with the aid of hypothermic total body retrograde perfusion.

Aneurysms involving either the aortic arch or the proximal descending thoracic aorta in five patients were resected with the aid of profound hypothermic total body retrograde perfusion. Traditional surgical management of the aortic arch and the descending thoracic aorta necessitates clamping of the aorta. However, this technique may be associated with rupture or atheroembolism. Rupture occurring at the clamping site may be difficult to repair. Atheroembolism to the brain compromises the neurologic system, and multiple organ embolism is associated with disseminated intravascular coagulopathy. Atheroembolism in cardiovascular surgery has become increasingly prevalent. It is necessary to prevent clamp injuries and to preserve the function of the vital organs, such as the brain, heart, and liver, during aortic reconstruction. We applied a total body retrograde perfusion technique to operations for aortic aneurysms. Total body retrograde perfusion consists of cerebral protection by continuous perfusion through the superior vena cava, intermittent retrograde coronary perfusion through the coronary sinus, and continuous abdominal visceral perfusion through the inferior vena cava. It can yield a relatively bloodless operating field without the need for aortic clamping. We believe this new adjunct offers excellent results in the surgical treatment of aneurysms of the aortic arch or adjacent structures.

Adult↗
PubMed1994

Red blood cell membrane and density changes under ambient and hypoxic conditions in transgenic mice producing human sickle hemoglobin.

Red blood cells (RBC) from patients with sickle cell disease (SCD) are characterized by membrane lesions caused by cell sickling and oxidative damage due to denatured hemichromes. We have developed three lines of transgenic human sickle hemoglobin (Hb S) mice, which produce 30, 50, and 80% human beta sickle globin (h beta S), by crossing transgenic progeny with nonthalassemic, heterozygous, or homozygous beta-thalassemic mice, respectively. Transgenic mice that produce Hb A, developed in a similar fashion, were used as controls. RBC from each transgenic line were examined for pathologic changes. RBC from 50 and 80% h beta S mice sickle upon deoxygenation in vitro while RBC from 30% h beta S mice and all Hb A mice do not. Density gradients of RBC from each Hb S line, including those from 30% h beta S that do not sickle, show broad distributions with increased dense fractions, similar to those of patients with SCD. RBC from Hb S lines exhibit elevated membrane-associated denatured hemoglobin (MADH) levels (0.250 +/- 0.080%) when compared to RBC from nontransgenic (0.073 +/- 0.021%) and transgenic Hb A (0.062 +/- 0.033%) mice. Elevated MADH levels in RBC from the 30% h beta S line suggest that membrane changes occur even though these cells do not sickle. These Hb S-dependent pathologic changes suggest that transgenic Hb S lines may be useful for the study of not only RBC sickling in vivo but also membrane oxidative damage and other chronic changes attributed to abnormal properties of both oxygenated and deoxygenated Hb S.

Anemia, Sickle Cell↗
PubMed1994

[A case of Cabrol's procedure in which selective cerebral perfusion was necessitated].

A 69-year-old man underwent Cabrol's procedure for annuloaortic ectasia and complicated multiple cerebral infarction. Preoperative CT scan showed atherosclerotic changes from the aortic arch to descending aorta. During extracorporeal circulation, arterial cannulation was made through left subclavian artery to prevent cerebral infarction due to detouched atheroma from the descending aorta. Intraoperatively, the ascending aorta was also atheromatous and ulcerative. In this case, cerebral infarction was most likely due to detouched atheroma from the aortic arch in retrograde blood flow during extracorporeal circulation. To prevent this complication, selective cerebral perfusion during extracorporeal circulation should have been selected.

Aged↗
PubMed1993

Re-evaluation of solid-phase adsorption and desorption techniques for isolation of trace organic pollutants from chlorinated water.

Amberlite XAD resin and activated carbon columns were tested for their abilities to concentrate trace organic pollutants in chlorinated water. Both XAD-2 and XAD-7 resin columns (20 ml) were capable of adsorbing about 30% of total organic halogen (TOX) present in 20 l of drinking water (pH 7) containing about 100 micrograms/l of TOX, whereas the carbon column (10 ml) adsorbed over 90% of TOX. The adsorption capacity of XAD-7 resin was found to be strongly dependent on the solution pH, as compared with those of XAD-2 and carbon adsorbents. Soxhlet and sonication extractions were also evaluated for their abilities to recover the adsorbed organics from the adsorbents, by measurements of TOX, chromatographable compounds and mutagenicity in the eluates. Soxhlet extraction gave higher recoveries than sonication, as measured with the above indices, but these differences were generally small (ca. 20%), with exception of the carbon extracts. The XAD-2 and XAD-7 extracts of drinking water also showed about 3-4 times higher mutagenic activity than the carbon extracts.

Acrylic Resins↗
PubMed1993

Pulse oximetry and factors associated with hemoglobin oxygen desaturation in children with sickle cell disease.

The observation of low transcutaneous arterial oxygen saturation (SaO2) in otherwise well sickle cell patients has lead to questions about the interpretation of pulse oximetry values in these patients. We undertook a prospective study of children with sickle cell disease to (1) determine the prevalence of, and factors associated with, low transcutaneous SaO2 in clinically well patients, (2) develop an algorithm for the use of pulse oximetry in acutely ill patients, and (3) assess the accuracy of pulse oximetry in these patients. Eighty-six clinically well children with hemoglobin (Hb) SS had a lower mean transcutaneous SaO2 than 22 Hb SC patients and 10 control subjects (95.6% v 99.1% v 99.0%, respectively; p < .001). In Hb SS patients, a history of acute chest syndrome and age greater than 5 years were associated with lower transcutaneous SaO2 (mean 93.8% for those with a history of acute chest syndrome v 97.8% for those without a history of acute chest syndrome, and 94.0% for patients > 5 years old v 97.2% for those < or = 5 years old; P < .001). These associations were not seen in Hb SC patients. During acute illness, Hb SS patients with acute chest syndrome had transcutaneous SaO2 values that were less than 96% and at least 3 points lower than measurements made when they were well. A nomogram was designed to aid in the interpretation of transcutaneous SaO2 in acutely ill Hb SS patients when a comparison value is not available. The accuracy of pulse oximetry was shown by the correlation between SaO2 measured by pulse oximetry and calculated by using the patient's oxygen dissociation curve and PaO2 (r = .97). This study provides evidence that Hb oxygen desaturation is not a universal finding among children with sickle cell disease and identifies factors associated with Hb oxygen desaturation. We conclude that pulse oximetry may be useful to assess whether progressive pulmonary dysfunction begins at an early age in Hb SS patients, and to assess acutely ill patients for the presence of hypoxemia associated with acute chest syndrome.

Anemia, Sickle Cell↗
PubMed1993

Effects of beta 6 amino acid hydrophobicity on stability and solubility of hemoglobin tetramers.

The relationship between different amino acids at the beta 6 position of hemoglobin and tetramer stability was addressed by a site-directed mutagenesis approach. Precipitation rates during mechanical agitation of oxyhemoglobins with Gln, Ala, Val, Leu and Trp at the beta 6 position increased 2, 5, 13, 21 and 53 times, respectively, compared with that for Hb A. There was a linear relationship between the log of the precipitation rate constant and amino acid hydrophobicity at the beta 6 position, suggesting that enhanced precipitation of oxy Hb S during mechanical agitation results in part from increased hydrophobicity of beta 6 Val. Deoxyhemoglobin solubility increased in the order of beta 6 Ile, Leu, Val, Trp, Gln, Ala and Glu suggesting that hydrophobic interactions between beta 6 Val and the acceptor site of another hemoglobin molecule during deoxy-Hb S polymerization not only depend on hydrophobicity but also on stereospecificity of the amino acid side chain at the beta 6 position. Furthermore, our results indicate that hydrophobic amino acids at the beta 6 position which promote tetramer instability in the oxy form do not necessarily promote polymerization in the deoxy form.

Hemoglobins↗
PubMed1993

A method for studying the structure of uniaxially aligned biopolymers using solid state 15N-nmr: application to Bombyx mori silk fibroin fibers.

Recent advances in the application of solid state nmr spectroscopy to uniformly aligned biopolymers have opened a window through which to view the detailed structure of biological macromolecules that are unable to be seen with standard techniques for structure determination such as x-ray diffraction. Atomic resolution structural details are obtained from solid state nmr data in the form of bond orientations, which yield the relative positions of specific atoms within the molecule. For static aligned systems such as fibers, in which rapid reorientation about the axis of alignment does not occur, it has generally been necessary to perform trial and error line-shape simulations to extract structural details from nmr spectra arising from a single type of nuclear spin interaction. In the present work, a new method is developed in which solid state 15N-nmr spectra obtained from uniaxially aligned molecules placed with the axis of alignment both parallel and perpendicular to the magnetic field are analyzed to yield the orientations of specific molecular bonds. Analytical expressions are derived that utilize spectral features read from 15N chemical shift anisotropy line shapes to calculate a discrete number of possible orientations for a specific site. The 15N-1H dipolar interaction is employed to further narrow the number of unique orientations possible for a given site. With this method, a neighborhood of possible orientations is quickly determined, and full line-shape simulations within this region of allowed space can be performed to refine the limits of orientation. This technique demonstrates the use of a single type of isotopic label to determine the orientation of a specific molecular group such as a peptide plane within a protein. Results from the application of this method to the Bombyx mori silk fibroin protein provide structural detail that is consistent with currently accepted structural models based on fiber diffraction studies.

Animals↗
PubMed1993

Selective jugular cannulation of safer retrograde cerebral perfusion.

Hypothermic retrograde cerebral perfusion is a new technique for protecting the brain. Satisfactory cerebral protection should be possible even for periods of retrograde perfusion greater than 60 minutes. However, there are some concerns that functioning venous valves at the jugular-subclavian junction may impede retrograde flow to the brain and consequently cerebral protection may not be adequate. To overcome this obstacle, we have developed an easy and safe technique of selective jugular cannulation through the right atrium using a central venous catheter and a guidewire. We have employed this technique successfully in 15 patients who underwent operation on the aortic arch.

Catheterization, Central Venous↗
PubMed1993

Prostacyclin analogue, beraprost, sustains recanalization duration after thrombolytic therapy in acute myocardial infarction model.

Platelets play an important role in acute reocclusion after thrombolysis in acute myocardial infarction. We tested a new antiplatelet agent, the stable prostacyclin analogue, beraprost, in the prevention of reocclusion of reperfused vessels with a combination of recombinant tissue-type plasminogen activator (rt-PA) in a canine preparation of coronary artery thrombosis superimposed on high-grade stenosis. Intravenous infusion of rt-PA (17 micrograms/kg/min for 30 min) was combined with beraprost (100, 200 or 300 ng/kg/min for 60 min) or aspirin (35 mg/kg bolus i.v. before rt-PA infusion). The reperfusion time did not differ among the 4 groups. The time from reperfusion to reocclusion (one cycle) in the rt-PA plus beraprost 200 ng/kg/min group was significantly longer than the rt-PA alone group (40 +/- 8 min vs. 9 +/- 2 min, P < 0.05) and the recanalization duration calculated as the mean time from reperfusion to reocclusion in each cycle was prolonged in the rt-PA plus beraprost 200 ng/kg/min group compared with the rt-PA alone group (48 +/- 6 min vs 18 +/- 5 min, P < 0.05) and the reocclusion time and recanalisation duration tended to be elongated in the rt-PA plus beraprost 300 ng/kg/min group, whereas those were not altered by aspirin and 100 ng/kg/min of beraprost. Bleeding time was slightly prolonged and ex vivo platelet aggregation was slightly depressed by beraprost and aspirin. Systemic blood pressure was lowered with higher doses of beraprost. Beraprost sustained coronary reperfusion time and recanalization duration at the higher doses with an optimal level, but could not eliminate reocclusion completely.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Comparative studies of phenothiazine derivatives for their effects on swelling of normal and sickle erythrocytes.

1. Three phenothiazines with similar structure; chlorpromazine (CPZ), triflupromazine (TFPZ), and trifluoperazine (TFP), were compared for the potency of swelling of normal red cells and antisickling effect of red cell from patients with sickle cell disease. 2. Normal erythrocytes treated with the phenothiazines became swollen within 60 min, and the percent increase in mean cell volume (MCV) was dose-dependent and varied according to the agent used. 3. The cell swelling was hematocrit-dependent, and pH-dependent. A greater swelling potency was seen at lower hematocrits and higher pH values. 4. The swelling was also dependent on the pKa values of these chemicals. TFP with the lowest pKa induced the highest degree of swelling while CPZ with the highest pKa induced the lowest. 5. The un-ionized fraction of the phenothiazines at a given pH was directly related to potency of the swelling. 6. The cell swelling was directly related to the binding affinities of the phenothiazines to calmodulin. 7. The antisickling effect of these compounds using sickle red cells, numerically estimated by an automated image analysis system, was found in the same order as that of swelling potency: TFP > TFPR > CPZ.

Adult↗
PubMed1993

Dose-dependent red blood cell volume increase induced by bepridil.

1. Bepiridil, (beta-[(2-methylpropoxy)methyl]-N-phenyl-N-(phenyl-methyl)-1-py rro lidine-ethanamine), a calcium channel blocker, inhibits sickling of red blood cells (RBC) from patients with sickle cell disease (SCD) at micromolar concentrations in vitro. 2. Bepridil induces dose-dependent osmotic swelling of RBC and a concomitant decrease in mean corpuscular hemoglobin concentration (MCHC). 3. Modest decreases in MCHC greatly lengthen the delay time for polymerization of deoxygenated sickle hemoglobin (Hb S) and inhibit RBC sickling. 4. Equilibrium dialysis studies of bepridil and purified hemoglobin showed a low binding affinity (Kb = 10(3)/M). 5. The partition coefficient (Kp) determined for the interaction of RBC and bepridil was 1-3 x 10(3), which is similar to the Kp determined for other amphipathic molecules, such as chlorpromazine.

Anemia, Sickle Cell↗
PubMed1993

Neurons containing gastrin releasing peptide-like immunoreactivity in the human pancreas.

Gastrin releasing peptide (GRP) is known to stimulate pancreatic enzyme and islet hormone secretion. In the present immunohistochemical study, the localization and distribution of GRP-like immunoreactivity were investigated in the human pancreas using two antisera with different specificities. GRP-like immunoreactivity (GRP-LI) was observed in numerous nerve fibers diffusely distributed to the exocrine pancreas, but was not seen in intrapancreatic nerve cells of normal pancreatic specimens examined. Nerve fibers and terminals with GRP-LI were found in abundance around pancreatic acini and capillaries, with moderate density around ductules and in the walls of arterioles, and a few were seen in islets. This distribution pattern was quite similar to that of vasoactive intestinal polypeptide (VIP)-LI nerve fibers. The study, using the antibody elution method, strongly suggests the co-localization of GRP- and VIP-LIs within a part of VIP-containing nerve fibers. In the chronic pancreatitis specimens, neurons with GRP-LI were frequently found, and > 90% of intrapancreatic nerve cells were VIP-immunoreactive. Immunostainings for GRP and for VIP on serial adjacent sections of intrapancreatic ganglia from chronic pancreatitis specimens suggested the co-localization of the two immunoreactivities in > 70% of intrapancreatic neurons. The present findings may provide a morphological basis for neurotransmitter and/or neuromodulator roles of GRP in the human pancreas.

Antibody Specificity↗