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Biomedical subjects

T Maeda

Publications and source records attributed to T Maeda.

At least 1,747 records · Page 97Linked to original sources
PubMedDate not supplied

Mycoplasma bovis-associated suppurative otitis media and pneumonia in bull calves.

Outbreaks of Mycoplasma bovis-associated otitis media and pneumonia occurred on four beef cattle farms in Hokkaido, Japan between 2000 and 2001. The morbidity and mortality were estimated at 8-40 and 30-100%, respectively. Eight calves with bilateral ear droop and exudative otitis media were examined bacteriologically and histopathologically. M. bovis was isolated post mortem from nasal swabs and from the ears, lungs, lymph nodes (cranial and pulmonary), brain and heart of all calves. At necropsy, suppurative exudates were observed in the tympanic bullae of all cases. Numerous abscesses were also found in the petrous portion of the temporal bone and lungs in seven cases. Histopathologically, the exudates within the tympanic bullae consisted of a mixture of neutrophils, necrotic cell debris and fibrin, and the tympanic mucosa was thickened with neutrophil and macrophage infiltration and proliferation of fibrous connective tissue. Pulmonary lesions included extensive foci of coagulative necrosis surrounded by numerous neutrophils. Hepatocytes or renal tubular epithelial cells were enlarged with hyaline cytoplasmic inclusions in four calves. Immunohistochemical labelling confirmed the presence of M. bovis antigen in the cytoplasm of the inflammatory cells in the middle ear, temporal bone and lungs, and was also demonstrated within the cytoplasmic inclusions of the hepatocytes and renal tubular epithelial cells. Ultrastructurally, mycoplasma-like organisms, 200-500 microm in diameter, were found within not only hepatocytes and renal tubular epithelia but also within axons of the facial nerves. The present results show that M. bovis spreads to multiple organs and is capable of invading various kinds of host cell. The intracellular localization may be favourable for evading host immune responses.

Animals↗
PubMedDate not supplied

A morphometric analysis of protein gene product 9.5-, substance P-, and calcitonin gene-related peptide immunoreactive innervation in the shoulder joint of the Japanese macaque.

The shoulder capsule and labrum of Japanese macaque monkeys were studied immunohistochemically with the use of antisera against protein gene product 9.5 (PGP 9.5), calcitonin gene-related peptide (CGRP), and substance P (SP) to further characterize the innervation of the supporting structures of the shoulder joint. With PGP 9.5 immunohistochemistry thick nerve fibers (diameter > or = 10 microm) presumed to be proprioceptive based on topographic location were found to be abundant in the posterior half of the capsule. Thinner fibers (diameter <10 microm) presumed to contain nociceptive and autonomic fibers were located in the posterior half of the capsule. Ruffini-like corpuscles were predominantly located in the inferior portion of the capsule. SP and CGRP immunoreactive thin fibers presumed to be nociceptive were abundant in the posterior half of the capsule. Thin fibers that appeared to be nociceptive fibers were found in the marginal portion and the parenchyma of the labrum, although the number was small. The predominant distribution of the Ruffini-like corpuscles in the inferior portion of the capsule suggest an important role of the inferior portion in generation of the proprioceptive output, which should be advantageous in stabilization of the joint in motion. The abundance of nociceptive fibers in the posterior half of the capsule may be responsible for the pathophysiological transmission of pain around the shoulder joint.

Animals↗
PubMedDate not supplied

Calcifying fibrous pseudotumor: an ultrastructural study.

To clarify the pathogenesis of calcification in calcifying fibrous pseudotumor (CFT), the lesion arising in the chest wall of a 16-month-old boy was ultrastructurally investigated. Fibroblasts were surrounded by large amounts of collagen fibrils. The dystrophic and psammomatous calcifications were observed as electron-dense amorphous masses and laminated bodies, respectively, within the cytoplasm of fibroblasts and in the collagenous stroma. The degeneration of cytoplasm seemed to be an initial event of intracytoplasmic calcification. Extracellular calcified substances often abutted to fibroblasts. Fibroblasts may play an important role in both intracellular and extracellular calcifications of CFT.

Calcinosis↗
PubMedDate not supplied

The role of leukocyte depletion in reducing injury to myocardium and lung during cardiopulmonary bypass.

Activated leukocytes and oxygen free radicals have been implicated in the pathogenesis of heart and lung injury after reperfusion and during cardiopulmonary bypass. This study was designed to determine whether leukocyte depletion prevents injury to the heart and lung during cardiopulmonary bypass. Twenty-eight open heart surgeries were performed in this study. In Group F, leukocyte depletion was performed with an LG-6 arterial line filter after aortic declamp (n = 14). Leukocyte depletion was not performed during cardiopulmonary bypass in Group C (n = 14). Thereafter, cardiac and lung function were assessed in the 24 hr after reperfusion. The total catecholamine dose used for 24 hr after reperfusion (r) was 61.9 +/- 13.4 in Group C and 43.9 +/- 19.2 in Group F (p < 0.05). CK-MB at 3 and 6 hr after reperfusion was 65.9 +/- 13.5 and 64.8 +/- 15.8 in Group C and 45 +/- 11.8 and 38 +/- 10.8 in Group F, respectively (p < 0.05). The pulmonary index after reperfusion at 3 and 6 hr was 1.7 +/- 0.5 and 1.3 +/- 0.4 in Group C and 0.7 +/- 0.3 and 0.6 +/- 0.4 in Group F, respectively (p < 0.05). There was significantly better preserved lung function in Group F. In conclusion, leukocyte depletion was significantly effective in preserving heart and lung function during cardiopulmonary bypass.

Adult↗
PubMedDate not supplied

Development of an antithrombogenic and antitraumatic blood pump: the Gyro C1E3.

The Gyro C1E3 is a centrifugal blood pump. Its antithrombogenic and antitraumatic blood features were demonstrated by prior studies. Based upon these studies, a mass production model of the C1E3 is becoming commercially available. Therefore, this feasibility study was conducted using the mass production models of the Gyro C1E3 for long-term cardiac assist in ex vivo animal experiments. Five healthy calves were used and 15 pump heads were applied for different time periods (Group 1, 30 days; Group 2, 14 days; Group 3, 10 and 7 days; Group 4, 4 days; and Group 5, 2 days). Activated clotting time (ACT) was kept at 200-250 sec. All five calves demonstrated neither abnormal signs nor abnormal blood examination data throughout the experiment. During necropsy, no thromboembolism was found in any downstream organs. Groups 1-4 showed thrombi inside the pump heads while two pumps in Group 5 had no thrombi formations. Bearing deformation or possible wear did not increase after 2 days of pumping. The C1E3 is capable of long-term assist circulation. However, after 2 days of pumping, careful observation is necessary since thrombi may occur inside the pump when ACT is controlled under 250 sec. During the weaning stage or low flow (under 2 L/min), over 250 sec of ACT is recommended to assure the safety of the patient.

Animals↗
PubMedDate not supplied

Development of an implantable small right ventricular assist device.

Currently, at least two permanent implantable left ventricular assist devices (LVADs) are used clinically. Unfortunately, there is no small implantable right ventricular assist device (RVAD) available, even though at least 25-30% of this patient population has right ventricular failure. If a small implantable RVAD were available, biventricular assist could support patients with right ventricular failure. A small atraumatic and antithrombogenic RVAD is being developed to meet this clinical need. This small centrifugal blood pump, the Gyro PI pump, is 6.5 cm in diameter and 4.6 cm in height and has three unique characteristics to prevent thrombus formation: (1) the double pivot bearing and magnetic coupling system enable this pump to be completely sealless; (2) the secondary vanes at the bottom of the impeller accelerate the blood flow and prevent blood stagnation; and (3) the eccentric inlet port enables the top female bearing to be embedded into the top housing and decrease blood cell trauma. The inflow conduit consists of a wire reinforced tube and a hat-shaped tip that is biolized with gelatin to create a thrombus resistant material. This conduit is directly implanted into the right ventricle, and the outflow conduit is anastomosed to the PA. The pump can be implanted inside the abdominal wall or in the thoracic cavity. Biocompatibility of this pump was proved in two calves by thrombus free implantation as an LVAD for 284 days and 200 days. Two RVAD implantations were conducted, aiming for 1-month system feasibility studies. During the month, the RVADs operated satisfactorily without any thromboembolic incident. No blood clots or abnormal findings were seen inside the pump, nor were there abnormal findings in the explanted lungs except for small areas of atelectasis. The pump flow was 3.02 +/- 0.38 L/min in calf 1 and 3.75 +/- 1.18 L/min in calf 2. The power requirement was 7.28 +/- 0.43W for calf 1 and 14.52 +/- 3.93W for calf 2. The PaO2 was 72.0 +/- 3.60 mm Hg (calf 1) and 72.0 +/- 7.63 mm Hg (calf 2); PaCO2 was 38.3 +/- 2.17 mm Hg (calf 1) and 34.1 +/- 1.95 mm Hg (calf 2); and SaO2 was 94.1 +/- 1.37% (calf1) and 95.0 +/- 1.95% (calf 2). Gas exchange via the lungs was maintained. These studies indicate that the Gyro PI pump is suitable as a single implantable RVAD, and is a feasible RVAD as a part of a BiVAD system in terms of pump performance and thrombus resistance.

Animals↗
PubMedDate not supplied

Preclinical evaluation of a hollow fiber silicone membrane oxygenator for extracorporeal membrane oxygenator application.

A silicone membrane hollow fiber oxygenator applicable for use as an extracorporeal membrane oxygenator (ECMO) has been developed in our laboratory. This silicone hollow fiber displays astonishing mechanical stability, is barely compressible or stretchable, and assembles easily while maintaining good gas permeability. The priming volume is 140 cc with a surface area of 0.8 m2. This study evaluated the gas transfer performances and biocompatibility of the oxygenator under ECMO and CPB conditions. In vitro studies that were performed at a blood flow rate of 2 L/min, and revealed O2 and CO2 gas transfer rates of 82.35 +/- 0.56 ml/m2/L/min and 38.72 +/- 2.88 ml/m2/L/min, respectively. The commercially available Kolobow (Avecor 1500) oxygenator was used as the control, and had O2 and CO2 gas transfer rates of 53.8 +/- 0.5 ml/m2/L/min and 24.7 +/- 2.0 ml/m2/L/min. To evaluate blood trauma, Normalized Index of Hemolysis (NIH) was measured according to American Society of Testing and Materials (ASTM) standards. The NIH findings were 0.0112 g/100L at a blood flow of 1 L/min, and 0.0152 g/100L at 5 L/min. Three ex vivo experiments, using a blood flow rate of 1 L/min, were performed with venoarterial bypass, and O2 transfer rate and CO2 transfer rate of the oxygenators were well maintained. This indicates that this preclinical silicone membrane hollow fiber oxygenator has superior efficiency, less blood trauma, and is smaller when compared with the only clinically available Kolobow oxygenator.

Animals↗
PubMedDate not supplied

Blood trauma induced by clinically accepted oxygenators.

Hemolysis remains one of the most serious problems during cardiopulmonary bypass (CPB), extracorporeal membrane oxygenation (ECMO), and percutaneous cardiopulmonary support (PCPS). However, the hemolytic characteristics associated with oxygenators are not well defined. A specialized hemolysis test protocol for oxygenators was developed. A comparative study was performed following this protocol to determine the hemolytic characteristics of the clinically available oxygenators during CPB; pressure drop measurements in the blood chamber were also performed. Four oxygenators (Medtronic Affinity, Cobe Optima, Terumo Capiox SX25, and Bard Quantum) were evaluated. Fresh blood from healthy Dexter calves anticoagulated with citrate phosphate dextrose adenine solution was used. The blood flow was fixed at 5 L/min, similar to that used in CPB. The Normalized Index of Hemolysis for Oxygenators (NIHO) has been modified according to the American Society of Testing and Materials (ASTM) standards. The NIH value, which was obtained from the circuit without an oxygenator, was subtracted from the primary NIH value, obtained from the circuit with an oxygenator to eliminate the effects of a centrifugal pump or other artifacts. The NIHO value was the lowest in the Affinity (0.0116 +/- 0.0017) and increased from Affinity < Optima (0.0270 +/- 0.0038) < Capiox (0.0335 +/- 0.0028) < Quantum (0.0416 +/- 0.0015 g/100 L). The Optima and Capiox did not demonstrate a significant difference. In addition, this NIHO value has a close relationship to the pressure drop. In conclusion, this new evaluation method is suitable to compare the biocompatibility performance of different types of clinically available oxygenators for CPB usage.

Animals↗
PubMedDate not supplied

Direct detection of red blood cell fragments: a new flow cytometric method to evaluate hemolysis in blood pumps.

Pump induced hemolysis is presently evaluated by measuring plasma free hemoglobin (fHb). However, this method has disadvantages because quantification of fHb depends on hematocrit (HCT) and hemoglobin (Hb) levels. The aim of this work was to devise a hemoglobin independent method, capable of quantifying cell trauma directly by measuring the number of red blood cell (RBC) fragments. Whole blood flow cytometry was used to quantify circulating RBC fragments derived from a roller pump (Sarns, Inc. Model 2 M 6,002) and a centrifugal pump (Gyro C1E3, Kyocera Corp.). The pumps were tested in a mock circuit for 2 hr (5 L/min flow against 100 mm Hg pressure head). Red blood cell fragments were quantified by a phycoerythrin (PE) labeled glycophorin A antibody specific for erythrocytes. Red blood cell fragments were smaller than the intact RBC population and overlapped in size with the platelet population (based on forward- and side-light scattering measurements). For the roller pump, the values for RBC fragments increased from 1,090 +/- 260/microl at 0 min to 14,880 +/- 5,900/microl after 120 min. In contrast, using the centrifugal pump, there was little increase in RBC fragments (from 730 +/- 270/microl at 0 min to 1,400 +/- 840/microl after 120 min). Flow cytometry can be used for the rapid, sensitive, hemoglobin independent evaluation of pump induced RBC trauma.

Erythrocytes↗
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Evaluation of cerebrospinal fluid flow through a Pudenz 12 mm or a standard Rickham reservoir: phantom experiments.

We have investigated the assessment of fluid flow through a Pudenz and a Rickham shunt using radioactive tracer. Experimentally, the radioactivity clearance curve obtained, using either shunt, is defined by two exponents. The relationship between flow-rate (F) and clearance half-time (T1/2) of the first component is identical with the clearance formula (formula: see text) or log10(F) =-LOG10(T1/2) + LOG100.693V using the physical volume. The value of the second component in a Pudenz 12 mm and a standard Rickman reservoir is log10(F) = -1.3LOG10(T1/2) + 0.087 and log 10(F) =-1.8log10(T1/2) + 0.019 respectively. In clinical practice, the first component may not be recorded adequately because the interval between appearance of the first and second components is very short. To calculate the CSF flow, we recommend referring to the line of "radioactivity clearance half-time and flow-rate" of the second component instead of the calculation based on clearance formula using a physical volume.

Cerebrospinal Fluid↗
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MRI of placental polyps.

OBJECTIVE: Placental polyp is intrauterine polypoid placental tissue retained after delivery or abortion and may cause life-threatening bleeding. We studied the value of MRI in diagnosing placental polyps. MATERIAL AND METHODS: Two women, 26 and 32 years old, with histologically proven placental polyp were included in this study. These patients were treated with local injections of methotrexate or transcatheter arterial embolization. The MR images before and after these treatments were studied retrospectively. RESULTS: High intensity pedunculated masses of 3-4 cm in size were observed in the expanded uterine cavity on T2-weighted and contrast-enhanced T1-weighted SE images. Bloody contents were observed around the masses. Placental polyps were more intensely enhanced than the myometrium by the contrast media, and the enhanced T1-weighted images indicated the retained placental tissues with an adherent part to the myometrium. Magnetic resonance imaging was also useful in following up the reduction in the size of the lesions and in the blood flow after the treatments. CONCLUSIONS: Magnetic resonance imaging may be useful in diagnosing and following up placental polyps.

Adult↗
PubMedDate not supplied

Inflammatory pseudotumors of the spleen: CT and MRI findings.

OBJECTIVE: Our goal was to elucidate the CT and MRI findings of inflammatory pseudotumors of the spleen. METHODS: The CT and MRI findings of three patients with inflammatory pseudotumors of the spleen were reviewed and compared with the pathologic findings. RESULTS: On the early phase of CT, the masses were hypodense to the normal spleen, and on the delayed phase, they demonstrated delayed enhancement. On T1-weighted MR images, the masses were isointense to the normal spleen, and on T2-weighted images, the masses had heterogeneous low signal intensities. After administration of Gd-DTPA, the masses showed delayed enhancement. CONCLUSION: Inflammatory pseudotumors of the spleen were characterized by low signal intensity on T2-weighted MR images and delayed enhancement after contrast material administration on CT and MRI. The fibrous stroma may contribute to these unusual findings.

Adult↗
PubMedDate not supplied

A long-term survivor of ruptured hepatocellular carcinoma after hepatic resection.

We treated a patient who had previously undergone a hepatic resection for ruptured hepatocellular carcinoma (HCC) but developed a solitary peritoneal recurrence at the site of the incision 8 years and 9 months later. Since no other recurrence was evident, we resected the tumour. The primary tumour was 2.5 cm in size and histological examination revealed HCC without any histological risk factors for intrahepatic recurrence. The peritoneal tumour consisted of less differentiated cancer cells than those found in the primary tumour. The positive rates of Ki-67 were 10% in the primary tumour and 23.3% in the peritoneal recurrence. The DNA indexes in both tumours were considered to be identical. The comparison between the primary and peritoneal tumours suggested that the histological differentiation and proliferation activity can change after recurrence, in spite of consistent DNA ploidy contents. Clinically, a patient who undergoes a hepatic resection for ruptured HCC can survive for a long time, such as 10 years, if they have good liver function and small HCC without any histological risk factors for intrahepatic recurrence. However, since late recurrence is possible, a follow up for as long as 10 years is recommended.

Aneuploidy↗
PubMedDate not supplied

CD34 expression in endothelial cells of small hepatocellular carcinoma: its correlation with tumour progression and angiographic findings.

The angiogenic process plays an important role in tumour growth and metastasis during hepatocarcinogenesis, but it is still uncertain when the process begins during tumour formation. Forty-two small hepatocellular carcinomas (HCC) that measured either less than or equal to 2 cm in diameter were studied by comparing the histologic findings with the angiographic findings, and with immunohistochemical expression of endothelial marker QB-end/10 (QB), a new monoclonal antibody raised against CD34, in the sinusoidal wall. Twenty (91%) of 22 moderately or poorly differentiated HCC revealed a positive reaction for QB, while only eight (40%) of 20 well differentiated HCC demonstrated a positive reaction (P < 0.01). In the tumours showing a 'nodule in nodule' appearance, the less differentiated areas were more reactive for QB. Twenty-three (82%) of 28 QB positive tumours were hypervascular, while only three of 14 (21%) QB negative tumours were hypervascular (P < 0.01) by angiography. All six of the poorly differentiated and 13 (81%) of the 16 moderately differentiated tumours were hypervascular, while only seven (35%) of 20 well differentiated HCC were hypervascular (P < 0.01). These results indicate that as the tumour becomes less differentiated, the QB positive areas become wider and angiography demonstrates hypervascularity. We therefore speculate that the HCC sinusoids acquire the characteristics of capillary and precapillary blood vessels during de-differentiation from well to moderate, and thus the tumour begins to reveal hypervascularity on angiography. The above process may be correlated with the stepwise progression of HCC.

Antigens, CD34↗
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Microangioarchitecture of rat parietal cortex with special reference to vascular "sphincters". Scanning electron microscopic and dark field microscopic study.

Microangioarchitecture of the rat parietal cortex was studied by means of scanning electron microscopy and dark field microscopy. The richest supply of blood vessels in the parietal cortex was found in layer III + IV and layer V, where 2 isolated plexuses of microvessels were prominent. The appearance of the plexuses was quite different between motor and sensory areas. In the motor area the capillary plexuses were narrow and compact, while in sensory area the plexuses were wide and diffuse. Characteristic ring formations, called ring-shaped-compressions in the present study, were frequently observed at branching sites of arterioles. The ring-shaped-compression probably corresponds to the precapillary sphincter. A similar structure was also seen in capillaries and venules and, therefore, it is likely that not only arterioles, but also capillaries and even venules, can actively change diameter to control cerebral blood flow.

Animals↗
PubMedDate not supplied

Sympathetic nerve terminals in the tunica media of human superficial temporal and middle cerebral arteries: wet histofluorescence.

In specimens from the superficial temporal artery (STA) and middle cerebral artery (MCA), obtained during STA-MCA anastomosis, green fluorescent varicose fibers of sympathetic nerves were clearly visible with both formaldehyde-glutaraldehyde and sucrose-potassium phosphate-glyoxylic acid wet-histofluorescent techniques. These fibers were fairly thick, were densely packed and had a meshwork-like arrangement. Fluorescent terminals were seen both in the adventitia and in the outer muscular layer of the media in both STA and MCA specimens. They were more often observed in patients with prominent atherosclerosis in these vessels. The present study suggests the possible role of sympathetic nerve terminals in the development of vasospasm and occlusive lesions in cerebral vessels. It may also help to explain the marked constriction and transient occlusion following a STA-MCA bypass procedure.

Adrenergic Fibers↗