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Biomedical subjects

S Ishimaru

Publications and source records attributed to S Ishimaru.

At least 91 records · Page 5Linked to original sources
PubMed1993

Relationship between blood flow and blood-brain barrier permeability of sodium and albumin in focal ischaemia of rats: a triple tracer autoradiographic study.

Local cerebral blood flow, the permeability of the blood-brain barrier to sodium and serum albumin, and the content of electrolytes were investigated in rats before and at 4 h and 24 h following permanent occlusion of the middle cerebral artery (MCA). Measurements were carried out by triple tracer autoradiography, using 131I-iodoantipyrin, 22NaCl and 125I-iodinated bovine serum albumin, respectively. Regional sodium and albumin transfer coefficients were calculated by multiple time point analysis, and correlated with the corresponding flow and tissue electrolyte values. In sham operated controls regional sodium and albumin transfer coefficients ranged between 2.16-2.30 x 10(-3) and 0.22-0.48 x 10(-3) ml/min per g, respectively. Four hours after MCA occlusion sodium and albumin transfer coefficients were unchanged although tissue sodium content was already increased. After 24 h the sodium-but not albumin-transfer coefficient increased 2-3 fold but the rise in tissue sodium content was slower than after 4 h. At both ischaemia times the unidirectional sodium influx was substantially higher than the actual changes of tissue sodium content. The development of stroke oedema is, therefore, not limited by the alterations of barrier permeability.

Animals↗
PubMed1992

Dual Bar homeo box genes of Drosophila required in two photoreceptor cells, R1 and R6, and primary pigment cells for normal eye development.

In the Bar mutation of Drosophila, ommatidial differentiation is known to be suppressed in the anterior portion of the eye. Our structural analysis shows that the Bar region contains a pair of homeo box genes, BarH1 and BarH2. These genes encode polypeptides similar in size and sequence and share a common homeo domain that is identical in sequence except for putative trans-activator-binding sites. We also show, by mosaic analysis and immunostaining with anti-BarH1/BarH2 antibodies, that BarH1 and BarH2 are not only specifically coexpressed but also functionally required in R1/R6 prephotoreceptors and primary pigment cells in developing ommatidia. In R1/R6, the expression of BarH1 and BarH2 appears to be regulated by rough and glass gene products. BarH1 and BarH2 proteins are essential to normal lens formation, formation of three types of pigment cells, and elimination of excess cells from mature ommatidia. Taken together, our results suggest that Bar homeo domain proteins may play key roles in the fate-determination processes of pigment cells and cone cells.

Amino Acid Sequence↗
PubMed1992

Small renal cell carcinoma: pathologic and radiologic correlation.

The authors correlated the radiologic and pathologic findings of 36 patients with small renal cell carcinoma (less than or equal to 3 cm in diameter). Tumors were discovered incidentally or by means of mass surveys with ultrasound (US). Computed tomography (CT) and angiography were performed before surgery. Of the 36 tumors, 24 were of solid (alveolar) architecture, five were of papillary architecture, three were of tubular architecture, and four were of multilocular cystic architecture. Cell arrangement was closely correlated with radiologic appearance, especially in regard to tumor vascularity and echogenicity. Histologically homogeneous tumors of solid architecture were hypoechoic at US and hypervascular at angiography and contrast medium-enhanced CT. Tumors of papillary, tubular, and multilocular cystic architecture were hyperechoic at US and hypovascular at angiography. There was no correlation of cell differentiation and cell architecture with echogenicity or tumor vascularity. Tumors with hemorrhage showed marked hyperattenuation at CT. A tumor capsule was observed in 25 patients (69%); this was demonstrated as a rim at US or angiography.

Adult↗
PubMed1992

[A case of ascending aortic dissection after aortic valve replacement in congenital bicuspid aortic valve].

Congenital bicuspid aortic valve is a risk factor of aortic dissection, but the case is rare in Japan. Several reports described ascending aortic aneurysm after aortic valve replacement. In these reports, most of aneurysms were false aneurysm, but the cases of ascending aortic dissection were rare. In this case, dissecting aneurysm of the ascending aorta occurred 4 years after aortic valve replacement, which was performed with mechanical prosthesis because of infective endocarditis, and it was repaired successfully by the modified Cabrol's method. This case was congenital bicuspid aortic valve, and had already been complicated with moderate aortic dilatation in the ascending aorta. In patients of congenital bicuspid aortic valve with aortic dilatation, consideration of complete replacement of the ascending aorta with aortic valve replacement is important.

Adult↗
PubMed1992

[Indication and results of surgical treatment of intermittent claudication].

In order to clarify the propriety of surgical treatment for intermittent claudication caused by arteriosclerosis obliterans (ASO), indication for vascular reconstruction and efficacy of surgery on patient's quality of life were investigated. Bypass surgery or laser angioplasty (PTLA) was undertaken in 149 of 188 ASO patients. Because of high risk factors (renal failure, ischemic heart disease, cerebro-vascular disturbance or malignant tumor), 39 patients were treated conservatively. Intellectual dysfunction in aged patient was evaluated by Okabe's brief mental scale test. Coronary artery disease was revealed by coronary angiography performed next to routine dipyridamole-loaded ECG in 19 to 78 patients. CABG or PTCA was performed prior to peripheral vascular reconstruction in 3 patients with serious coronary disease. Extra-anatomical bypass or PTLA was indicated mainly in patients with coronary artery disease or intellectual dysfunction. The anatomical bypass and the extra-anatomical bypass were undertaken in 88 and 61 patients respectively. Graft occlusion was observed in 8 cases. Patency rate of the anatomical bypass was 96.6% and that of the extra-anatomical bypass was 91.8%, at 32 months of postoperative mean follow-up period. The operative mortality rate was 2.7%. There was no major amputation due to graft occlusion.

Aged↗
PubMed1992

[A successful case of thoracic aortic aneurysm with mixed cryoglobulinemia].

Cold-reactive proteins, such as cold agglutinins, cryoglobulins, and cryofibrinogens, are reversibly precipitates, or gel, upon exposure to cold temperatures. Cryoglobulins are usually not of importance, but under special conditions, such as surgical hypothermia, hyperviscosity and damage in microcirculation may occur in patients with high plasma concentration of cryoglobulins. Several groups have reported their efforts to reduce further the risks of surgical hypothermia in patients with cold agglutinins, but rarely in patients with cryoglobulins. A 57-year-old woman with thoracic aneurysm, requiring replacement of the ascending aorta and the aortic arch, had mixed cryoglobulinemia (cryocrit 29%) associated with rheumatoid arthritis. Steroids therapy and preoperative plasmapheresis were performed, and cryocrit levels were decreased until 0% before operation. Systemic hypothermia (25 degrees C), hemodilution techniques during cardiopulmonary bypass, and cold crystalloid cardioplegia were successfully employed, and no clinical evidence of microcirculation damage was posed after operation.

Aorta, Thoracic↗
PubMed1992

[A case of aberrant left pulmonary basal aneurysm arising from the descending aorta].

A 65-year-old man was referred to our hospital because of fever and abnormal shadow in the left lung. An aortogram revealed a large artery arising from the descending aorta supplying the left basal segment and, which then flowed into the pulmonary vein. This artery had an aneurysm and 30 mm in diameter. Bronchography showed compression of the left basal branch. A clinical diagnosis of an aberrant left pulmonary basal aneurysm arising from descending aorta was made, and left lower lobectomy was performed, because of the danger apprehension of the aneurysmal rupture. The procedure was successful. There are only 15 case reports of a systemic artery supplying the lung with normal bronchial branch in Japan. Differences of this anomaly from pulmonary sequestration were discussed.

Aged↗
PubMed1991

Identification of a different-type homeobox gene, BarH1, possibly causing Bar (B) and Om(1D) mutations in Drosophila.

The Bar mutation B of Drosophila melanogaster and optic morphology mutation Om(1D) of Drosophila ananassae result in suppression of ommatidium differentiation at the anterior portion of the eye. Examinations was made to determine the genes responsible for these mutations. Both loci were found to share in common a different type of homeobox gene, which we call "BarH1." Polyptides encoded by D. melanogaster and D. ananassae BarH1 genes consist of 543 and 604 amino acids, respectively, with homeodomains identical in sequence except for one amino acid substitution. A unique feature of these homeodomains is that the phenylalanine residue in helix 3, conserved in all metazoan homeodomains so far examined, is replaced by a tyrosine residue. By Northern blotting, considerably more BarH1 RNA was detected in the Bar mutant than in wild type. P element-mediated transformation showed Bar-like eye malformation to be induced by transient overexpression of the BarH1 gene in the late third-instar larvae. Somatic recombination analysis indicated normal gene functions of the Bar region, including the BarH1 gene, to be required for normal eye morphogenesis.

Amino Acid Sequence↗
PubMed1991

Two-stage resuscitation of the cat brain after prolonged cardiac arrest.

Following prolonged cardiac arrest, reperfusion of the brain is endangered by the low blood perfusion pressure during the early resuscitation phase. In order to avoid low perfusion brain injury, a two-stage resuscitation protocol was applied to cats submitted to 30 min potassium chloride induced cardiac arrest: first, the heart was resuscitated, followed--after stabilisation of blood pressure--by recirculation of the brain. During cardiac resuscitation the brain was disconnected from the general circulation by inflating a pneumatic cuff around the neck. The results were compared with the outcome of conventional one-stage resuscitation following 15 min cardiac arrest. Cardiac resuscitation was successful in 5 out of 8 animals with 15 min and in 6 out of 13 animals with 30 min cardiac arrest. In successfully resuscitated animals of both groups, brain energy metabolism recovered to normal within 3 h although two-stage resuscitation increased brain ischemia time to 37-61 min. Two-stage resuscitation, in consequence, is a promising approach for revival of the brain after prolonged cardiac arrest.

Adenosine Triphosphate↗
PubMed1991

Ischemic thresholds of cerebral protein synthesis and energy state following middle cerebral artery occlusion in rat.

The ischemic threshold of protein synthesis and energy state was determined 1, 6, and 12 h after middle cerebral artery (MCA) occlusion in rats. Local blood flow and amino acid incorporation were measured by double tracer autoradiography, and local ATP content by substrate-induced bioluminescence. The various images were evaluated at the striatal level in cerebral cortex by scanning with a microdensitometer with 75 microns resolution. Each 75 x 75 microns digitized image pixel was then converted into the appropriate units of either protein synthesis, ATP content, or blood flow. The ischemic threshold was defined as the flow rate at which 50% of pixels exhibited complete metabolic suppression. One hour after MCA occlusion, the threshold of protein synthesis was 55.3 +/- 12.0 ml 100 g-1 min-1 and that of energy failure was 18.5 +/- 9.8 ml 100 g-1 min-1. After 6 and 12 h of MCA occlusion, the threshold of protein synthesis did not change (52.0 +/- 9.6 and 56.0 +/- 6.5 ml 100 g-1 min-1, respectively) but the threshold of energy failure increased significantly at 12 h following MCA occlusion to 31.9 +/- 9.7 ml 100 g-1 min-1 (p less than 0.05 compared to 1 h ATP threshold value; all values are mean +/- SD). In focal cerebral ischemia, therefore, the threshold of energy failure gradually approached that of protein synthesis. Our results suggest that with increasing duration of ischemia, survival of brain tissue is determined by the high threshold of persisting inhibition of protein synthesis and not by the much lower one of acute energy failure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1991

Platelet adhesion to a biomimetic prosthesis prepared from canine arterial wall.

A biomimetic prosthesis was prepared from canine arterial wall by extraction with 70% formic acid. Under these conditions, the arterial architecture consisting of elastic lamella was conserved and the tensile strength was retained. Attachment of 51Cr-endothelial cells to the surface of the prosthesis was enhanced in the presence of collagen (50 micrograms/ml), fibronectin (20 micrograms/ml), and fibrinogen (500 micrograms/ml). These agents also enhanced the adhesion of 51Cr-platelets. However, preattachment of endothelial cells to prostheses prevented platelet adhesion.

Acetates↗
PubMed1991

[Cardiac assist device with inserted alternate-drive skeletal muscle pump system].

Many studies on a skeletal muscle pump (SMP) for use as a cardiac assist device require preconditioning as a countermeasure to muscle fatigue. However, we conducted experiments in the hope of developing a cardiac assist device with an alternate-drive SMP system requiring no preconditioning. Adult mongrel dogs were used. We prepared a roll-type SMP from a pedicled muscle flap of the latissimus dorsi and major pectoris muscle, and an insert type SMP without separating the latissimus dorsi and major pectoris muscle. The muscles were stimulated at a frequency of 60 rpm at cycles of burst stimulation. Thirty-minute intermittent driving was performed. The hydrodynamic changes were measured at five-minute intervals for a total of three hours. The function of the pumps markedly declined after a few minutes of driving the roll-type SMPs but remained satisfactory after thirty minutes of driving the insert-type SMPs. Consequently, we concluded that dual SMPs, alternately driven through thirty minute intermittent drive and rest intervals, could be useful as cardiac assist devices without preconditioning.

Animals↗
PubMed1991

[Clinical study of centrifugal pump bypass as an auxiliary technique for surgical treatment of descending thoracic aorta].

Left heart bypass or arterial bypass using a centrifugal pump (Bio-pump bypass) with a H-PSD shunt tube was performed as an auxiliary technique for the treatment of descending thoracic aorta in 13 cases. Hemodynamic differences during aortic clamp were compared between cases using Bio-pump bypass and 4 cases of axillo-femoral temporary bypass which were carried out in the first term. Furthermore, in Bio-pump bypass cases, the bypass route was investigated from the point of view of operative complications in relation to bypass technique. Peripheral blood pressure and urinary output during aortic clamp were significantly increased in the Bio-pump bypass group. Those results indicated that the Bio-pump bypass was useful as an auxiliary technique especially for high risk patients with low renal function. In particular, left heart bypass was a beneficial technique which was not affected by modality or region of disorder in the descending thoracic aorta. However, this technique should be selected carefully for patients with cardiac disease, for instance severe left ventricular hypertrophy, because two cases of operative complications consisting of pericardial effusion related to the bypass technique were experienced in this study.

Aorta, Thoracic↗
PubMed1991

[Haptoglobin administration for hemolysis with autotransfusion of blood ultrafiltered after cardiopulmonary bypass].

Ultrafiltration is well known as a useful method of hemoconcentration of the blood after cardiopulmonary bypass, but free hemoglobin increase is a problem in autotransfusion. The purpose of this study was to investigate the effect of haptoglobin administration for hemolysis with autotransfused blood ultrafiltered after cardiopulmonary bypass. By means of haptoglobin administration, autotransfusion of blood ultrafiltered with Hemocon (CD Medical Inc.) composed cellulose acetate membrane was performed in patients over a long period (max 313 min) of cardiopulmonary bypass, and with high serum free hemoglobin levels (max 128 mg/dl) at the end of the cardiopulmonary bypass. Comparing the prophylactic administration with the therapeutic administration of haptoglobin, both methods effectively prevented the increment of serum free hemoglobin level, but prophylactic administration (priming administration) was safer and more useful considering free hemoglobin level in ultrafiltered blood and changes of serum free haptoglobin, free hemoglobin and creatinine clearance during and after the operation.

Adult↗
PubMed1991

[Cardiac assist device with skeletal muscle ventricle--alternate-drive twin pump system as a countermeasure to prevent skeletal muscle fatigue].

Many studies on cardiac assist devices using skeletal muscle ventricle (SMV) require preconditioning for 6-9 weeks as a countermeasure to prevent skeletal muscle fatigue. Therefore this method does not seem to be indicated in cases of acute heart failure. However we performed experiments to develop Alternate-Drive Twin SMVs as a cardiac assist device without preconditioning. Adult mongrel dogs were used. In order to obtain adequate alternating SMV during pattern, fundamental experiments were performed. The function of SMVs prepared by rolled pedunculated sartial muscle was studied hydrodynamically in three groups; continuous driving for one hour in group a (n = 3): intermittent driving for 3 hours in group b (n = 15): intermittent driving for 12 hours in group c (n = 3). Group b was divided into three subgroups with interval for 10 minutes in subgroup I (n = 5), for 20 minutes in subgroup II (n = 5), for 30 minutes in subgroup III (n = 5). In group b and c, the recess interval between driving was set the same as the driving interval in each subgroup. All SMVs were stimulated by electrical bursts. In every experiment pump pressure, pump max dp/dt and pump stroke work index/10 kg body weight were measured for 3 hours. In subgroups I and II, pump function decreased gradually, however, the parameters did not show any change for up to 3 hours in subgroup III. We defined the reduction ratio as the difference of parameters before and after driving divided by the value at the start of driving.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Relationship between cerebral blood flow and blood-brain barrier permeability of sodium and albumin in cerebral infarcts of rats.

The permeability of the blood-brain barrier to sodium and albumin was investigated in rats following occlusion of the middle cerebral artery. Regional blood flow and unidirectional transfer coefficients of sodium and albumin were measured by triple tracer autoradiography, and tissue electrolyte content by atomic absorption spectroscopy. In sham-operated controls regional transfer coefficients of sodium ranged between 1.3 and 3.2 x 10(-3) ml.g-1.min-1; the transfer coefficient of albumin was below the detection limit of autoradiography. During the initial 4h of vascular occlusion neither albumin nor sodium permeability changed although tissue sodium content increased from 56 +/- 3 to 76 +/- 8 mumol.g-1. After 24 h transfer coefficient of sodium rose to between 2.91 and 7.0 x 10(-3) ml.g-1.min-1, and tissue sodium content to 90 +/- 9 mumol.g-1. Despite this rise the net uptake rate of sodium was 4 to 60 times lower than the unidirectional influx, indicating that permeability changes of the blood-brain barrier are without relevance for the development of stroke oedema.

Animals↗