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Biomedical subjects

Y Okazaki

Publications and source records attributed to Y Okazaki.

At least 343 records · Page 19Linked to original sources
PubMedDate not supplied

Age-dependent changes of mineral contents in men and women's calcanei.

To elucidate age-related change of mineral contents in human bones, the mineral content and density of human calcanei were determined by inductively coupled plasma atomic emission spectrometry and dual-energy X-ray absorptiometry. Calcanei were removed from 27 subjects (17 men and 10 women) who died in the age range from 40-98 yr old. Both the inductively coupled plasma emission spectrometry and dual-energy X-ray absorptiometry indicated that there were age-dependent decreases of the mineral contents and density in the men's calcaneus in the age range from 40-98 yr, but not in the women's calcaneus in the age range from 42-87 yr. It was also found that the calcanean masses of the men and women remained constant within the same age range until 98 yr.

Absorptiometry, Photon↗
PubMedDate not supplied

Free radical scavengers suppress the accumulation of platinum in the cerebral cortex.

We investigated whether free radical scavengers and antioxidants inhibit the accumulation of platinum (Pt) in the cerebral cortex. Pt was detected in the cerebral cortex of mice after administration of cisplatin and exposure to short-term hypoxia. When mice were treated with either allopurinol (20 mg/kg) or catalase (100 mg/kg) before cisplatin administration and low oxygen exposure, Pt was not detected in the cerebral cortex. However, Pt was detected in the cerebral cortex of mice pretreated with either a low dosage of allopurinol or heat-denatured catalase. Furthermore, Pt was detected in the cerebral cortex of mice preadministered vitamin C, vitamin E, or deferoxamine. Lipid peroxide levels in the cerebral cortex increased 10 min after the treatment of hypoxia, and peaked 30 min after the treatment. These results suggested that short-term hypoxia produces free radicals, which allows Pt to pass through the blood-brain barrier and accumulate in the cerebral cortex, and that the production of free radicals is reduced by the administration of either allopurinol or catalase, which prevents Pt from passing through the barrier.

Allopurinol↗
PubMedDate not supplied

Age-dependent aluminum accumulation in the human aorta and cerebral artery.

The purpose of this study was to determine the extent of aluminum (Al) accumulation in the human aorta and cerebral arteries. The Al contents in the aortae and in the cerebral arteries from 23 human subjects was determined by inductively coupled plasma atomic emission spectrophotometry (ICP-AES). The subjects' age range was 45-99-yr-old; 15 of the subjects were males and 8 were females. Al was detected in twelve aortae and in six cerebral arteries, when the entire specimen was analyzed. Two specimens where Al was found in the cerebral arteries contained no Al in the aorta. No relationship to the subject's sex was found. When related to age, two groups were established. Group L (45-75 yr old) and group H (> 75 yr old), which exhibited aortal Al concentrations of 33.3 and 72.7%, respectively. When the aortic wall was dissected into the tunica intima, media, and adventitia, Al was found mainly in the tunica media. In the aorta, significant relationships were found between Al and phosphorus (P) levels (r = 0.801, p < 0.01) and between Al and calcium (Ca) (r = 0.661, p < 0.05). We have concluded that Al accumulation is age-dependent and that it occurs both in the aorta and in the cerebral artery. In the aorta, accumulation occurs mainly in the tunica media. Both P and Ca appear to enhance aortal Al accumulation.

Aged↗
PubMedDate not supplied

A high accumulation of minerals in human internal jugular vein.

To elucidate age-related changes of mineral contents in human veins, the relative contents (RCs) of elements in the human internal jugular veins, superior and inferior venae cavae, and femoral veins from 27 subjects ranging from 40 to 98 yr old were analyzed by inductively coupled plasma atomic emission spectrometry. The average RCs of calcium in the 27 specimens were the highest in the internal jugular vein, followed in descending order by the superior vena cava, femoral vein, and inferior vena cava. The RCs of calcium and phosphorus in the internal jugular veins started to increase after the age of 50 yr, became the highest in subjects in their 60s and thereafter decreased gradually. It is noted that such accumulations of minerals, similar to the internal jugular vein, were also found in the veins, such as the superior and inferior venae cavae, and femoral vein. Accumulation of minerals in the veins is different from that of arteries, which increase progressively by aging, but do not decrease.

Adult↗
PubMedDate not supplied

Tissue platinum after clinical treatment with cisplatin or carboplatin in tumor-bearing patients.

Tissue platinum (Pt) levels were measured in tumor-bearing patients treated with either cisplatin or carboplatin. Cisplatin was given by intra-arterial, intraperitoneal, and intravenous (iv) administrations. After death, vertebrae and intervertebral disks were removed from eight human subjects, and livers and kidneys were removed from the half of them. When cisplatin was administered intraperitoneally, Pt of the liver was higher than that of the kidney, and a high content of Pt was detected in the vertebra by comparing with the other administration methods. At the intra-arterial administration of cisplatin, Pt was mainly accumulated in the kidney. At the iv administration of cisplatin, a high level of Pt was found in the vertebra and intervertebral disk, especially at the highest value at 10.31 micrograms/g in the intervertebral disk of one case, whereas a low level of Pt was detected in the liver. On the contrary, it was found that the iv administration of carboplatin did not result in high accumulations of Pt in the liver, kidney, intervertebral disk, and vertebra. Therefore, Pt is accumulated in different organs, depending on the way cisplatin is administered, but Pt is accumulated least in them by the administration of carboplatin.

Adult↗
PubMedDate not supplied

Plasma and testicular testosterone in experimental diabetic rats.

Testicular and plasma testosterone levels were found to be decreased markedly in streptozotocin diabetic rats compared with those of controls. Treatment with 6 units NPH insulin daily for one week almost normalized plasma testosterone levels parallel to the increase in body and liver weights in diabetic rats, while testosterone levels in testicles were not significantly changed. Plasma prolactin and LH levels were unchanged among control, diabetic and diabetic insulin-treated rats. Thus, testosterone reduction in the testis might play a role in diabetic impotence.

Animals↗
PubMedDate not supplied

Anatomic fitting studies of a total artificial heart in heart transplant recipients. Critical dimensions and prediction of fit.

Anatomic fitting studies of the Cleveland Clinic-Nimbus total artificial heart were performed in 33 patients undergoing heart transplantation. The pump fit in the pericardial space in 20 men (80%) and 4 women (50%). There was no significant difference between the Fit and Non-Fit groups in external chest dimensions. Among 42 intrathoracic dimensions, the distance from the center of the mitral valve to the diaphragm (Fit: 5.6 +/- 2.2 cm, Non-Fit: 3.6 +/- 0.4 cm, p < 0.00001) and the distance from the caudal end of the pulmonary valve to the diaphragm (Fit: 9.4 +/- 1.6 cm, Non-Fit: 6.3 +/- 0.8 cm, p < 0.0001) were the most critical. To predict anatomic fit, an index (A x B x C) was obtained from chest X-ray measurements (A, the craniocaudal distance from the dorsal region of the 8th left rib to the left diaphragm; B, the maximum left chest width; and C, the maximum anteroposterior sternum-vertebrae dimension). The pump fit in 88.5% of the patients with an index above 1200 cm3, whereas it fit in only 14.3% of the patients with an index below 1200 cm3 (p < 0.001). This index was an easily obtainable, good predictor of anatomic fit.

Diaphragm↗
PubMedDate not supplied

Microencapsulated vaccines to provide prolonged immunity with a single administration.

Vaccines that provide lasting immunity with a single administration of the antigen can reduce the cost of routine immunization programs while increasing their efficacy by lessening the need for patient compliance. The authors have been developing methods for using biodegradable polymer microspheres to encapsulate vaccines. These microcapsules are designed to provide timed release of the antigen on a schedule that mimics conventional booster shots. The microspheres are made from poly-DL-lactide-co-glycolide. The rate of biodegradation of this polymer is controllable by varying the molar ratio of the monomers. High performance liquid chromatography was used to measure release kinetics in vitro, and a process was developed for the encapsulation of water soluble protein antigens. This process then was used to prepare a microencapsulated vaccine for type A botulism made using a recombinant C fragment antigen. A series of 27 adult C57BL/6J mice were used to study the efficacy of this vaccine. Six mice injected with saline filled microspheres served as a control group. Plasma samples were taken weekly to measure antibody levels using enzyme linked immunosorbent assay. At 14 weeks, 21 immunized mice and six control subjects were used for an aerosol challenge test with botulinum toxin. All control subjects died within 72 hrs. Fifteen (71%) of the immunized mice survived.

Animals↗
PubMedDate not supplied

Platelets are deposited early post-operatively on the leaflet of a mechanical heart valve in sheep without post-operative anticoagulants or antiplatelet agents. A scanning electron microscopic observation of the pyrolytic carbon surface in a mechanical heart valve.

Pyrolytic carbon has been used for mechanical heart valves as a thromboresistant, wear resistant, and fatigue resistant material. Thrombosis and thromboembolism, however, remain major mechanical heart valve associated complications and may frequently occur during the early post-operative period. In depth morphologic studies on blood-pyrolytic carbon surface interactions are limited. The purpose of this study was to evaluate the blood compatibility of the pyrolytic carbon surface of St. Jude Medical mechanical heart valves that were implanted in the mitral position of sheep without the administration of post-operative anticoagulants or antiplatelet agents for 2, 4, and 6 weeks. Almost the entire leaflet and orifice ring surfaces were observed by scanning electron microscopy. Although the surfaces appeared clean macroscopically, when observed by electron microscopy, the surface were mottled, mainly by solitary platelets and aggregations. There were only a few leukocytes or red blood cells observed. No fibrin clots were observed on the leaflets. The density of platelet deposition was higher in the vicinity of the pivots and near the edges of the leaflets. The sizes of the platelet aggregations decreased with longer duration. The outer surfaces of the pivot guards were covered by various amounts of deposition composed of platelet aggregations and thrombi. Thus, the administration of antiplatelet agents is recommended during the early post-operative period after mechanical heart valve implantation.

Animals↗
PubMedDate not supplied

Systemic hypertension as a risk factor for complications with an aortic mechanical valve.

We sought to determine the effect of preoperative systemic hypertension on prosthesis related complications or postoperative aortic dissection after valve replacement in patients with aortic regurgitation. The patients were divided into two groups according to the presence or absence of systemic hypertension: Group I, with hypertension (n = 35), and Group II, without hypertension (n = 37). The survival rate and event free rate were examined for 72 patients who were alive 30 days after valve replacement with a St. Jude Medical valve for aortic regurgitation. The cumulative 10 year survival rate of Group I (65% +/- 12%) was lower than that of Group II (79% +/- 15%). The 10 year event free rate of all prosthesis related complications was 62% +/- 13% in Group I, and 96% +/- 3% in Group II (p < 0.05). The 10 year event free rate for ascending aortic dissection was 73% +/- 12% in Group I and 100% in Group II (p < 0.05). The linearized event rate of all prosthesis related complication was 3.8% per patient-year in Group I and 0.5% per patient-year in Group II. In conclusion, systemic hypertension was a risk factor for prosthesis related complications and for complicated aortic lesions after aortic valve replacement. Careful postoperative management for hypertension is necessary in patients with systemic hypertension after aortic valve replacement. Tissue valves may be recommended in patients with aortic valve disease and severe hypertension.

Aortic Valve↗
PubMedDate not supplied

In vivo cell kinetics studies of the duodenum during and after healing of cysteamine-induced duodenal ulcer in rats using bromodeoxyuridine incorporation.

The present study investigated the defect of duodenal defence responsible for the tendency of recurrence of duodenal ulcer. Male Wistar rats were treated with cysteamine-HCl subcutaneously to induce duodenal ulcer, and bromodeoxyuridine (BrdU) was given intraperitoneally 1 h before laparotomy. Serial tissue sections and immunocytochemical staining of BrdU were done to study the cell kinetics during and after healing. Deep ulcers developed in the proximal part of the duodenum 24 h after cysteamine injection, and the ulcer was replaced by scar tissue 1 week later. BrdU-labelling index of normal duodenal mucosa in control rats was 30-34%. On the peripheral part of the regenerative mucosa, BrdU-labelling index increased from 1.5% to 26-27%, 1-4 weeks after injection and remained at this level thereafter. On the central part, except the most central area, the labelling index remained at 0% until 3 weeks, and was 15% 6 weeks after cysteamine treatment. It never achieved the level seen in control normal mucosa. The labelling rate of fibrous cells in scar tissue decreased from 28% to nearly 0% 1-4 weeks after the injection. It is concluded that both the ulcer scar and the regenerative mucosa do not achieve a mature state in the initial scarred stage; they need more time to reach a relatively mature condition. Moreover, the regenerative mucosa will be the weak, easily damaged part of the duodenum.

Animals↗
PubMedDate not supplied

Case report: spontaneous hemangiosarcoma in the pancreas of a Fischer rat.

Spontaneous hemangioma or hemangiosarcoma is sometimes found in the viscera and soft tissue of rats and mice. However, there is no report of the tumor occurring in the pancreas of rats. We report a pancreatic hemangiosarcoma in a 109-wk-old, male Fischer 344 rat, which was used in the control group of a carcinogenicity study. The tumor destroyed and compressed the normal pancreatic tissue and displayed a high density in terms of the numerous capillaries and strands of endothelial tumor cells. A reticulin stain revealed a dense network formation. The frequency of proliferating cell nuclear antigen-positive staining showed active proliferation of the tumor cells. Immunohistochemically, some of the tumor cells stained positive with factor VIII-related antigen, and ultrastructurally, Weibel-Palade bodies were rarely observed in the cytoplasm of the tumor cell. From these findings, the tumor was diagnosed as a hemangiosarcoma that occurred naturally in the pancreas.

Animals↗
PubMedDate not supplied

[Studies on early changes in myocardial electrolytes and histological reaction in isoproterenol-induced myocardial injury].

To determine morphological changes in the very early stage of damage and recovery of myocardial fibers in relation to electrolytes and water content in the myocardium, experimental myocardial infarcts were produced after injection of 75 mg/kg isoproterenol (Isp) to rats weighing 270 +/- 10 g. Electrolytes were examined by an atomic absorption spectrophotometer, and histologic examination was performed by light and electron microscopy. At 30 min after Isp injection, Ca and water contents of myocardium increased, but Mg decreased. These myocardial damages showed a maximum level from 6 to 12 h after injection of Isp. It consisted of reversible injury of muscle fibers represented by eosinophilic and fatty degeneration, intermingled with coagulation necrosis of fibers which was irreversible. Most of these eosinophilic degeneration fibers recovered to normal fibers between 12 h and 3 d after the injection. The chronological changes of Ca, Mg, and water contents were well correlated to the morphological early changes of myocardial fibers, and this experimental model by using Isp may be useful for examining the recovery of damaged myocardial tissue and estimating the effects of therapeutics.

Animals↗
PubMedDate not supplied

Superoxide dismutase enhances both adenosine release and coronary hyperemic flow through protection of 5'-nucleotidase against its degradation during reperfusion following ischemia in dogs.

Oxygen-derived free radicals are thought to inactivate ectosolic enzymes that regulate myocardial cellular functions. One such enzyme is ecto-5'-nucleotidase, which is responsible for adenosine production during coronary hyperemic flow. In the present study, we measured both reactive and hyperemic flow and adenosine release during reperfusion with and without superoxide dismutase. In 10 open chest dogs, the left anterior descending coronary artery was perfused through an extracorporeal bypass tube from the carotid artery. In the control hearts, a five-minute occlusion of the coronary artery caused the hyperemic flow with increased release of adenosine. In the superoxide dismutase-treated hearts, although administration of superoxide dismutase altered neither adenosine release nor coronary blood flow in the baseline, it augmented both peak coronary blood flow and repayment, and adenosine release during reperfusion. Therefore, we hypothesized that superoxide dismutase reduces generation of oxygen-derived free radicals during ischemia and reperfusion and attenuates the degradation of ecto-5'-nucleotidase. The administration of superoxide dismutase enhanced the increase in ecto-5'-nucleotidase activity at 10 minutes after reperfusion over the untreated group. Thus, we conclude that superoxide dismutase enhances reactive hyperemic flow and adenosine release during reperfusion following ischemia, which may be attributable to the protection of ecto-5'-nucleotidase by superoxide dismutase during ischemia and reperfusion.

5'-Nucleotidase↗
PubMedDate not supplied

Neoadjuvant intra-arterial infusion chemotherapy combined with hormonal therapy for locally advanced breast cancer.

To determine the efficacy of combined neoadjuvant intra-arterial infusion chemotherapy and hormonal therapy for treating locally advanced breast cancer, we compared the outcomes of patients with or without this therapy, and also assessed histologic response. Ninety-four patients with locally advanced breast cancer (stage IIIa, 56; stage IIIb, 38). Nineteen stage IIIa and 17 stage IIIb patients received intra-arterial plus hormonal therapy while 37 stage IIIa and 21 stage IIIb patients with similar ages and follow-up durations did not. Treated patients received intra-arterial epirubicin plus oral medroxy-progesterone. Five-year disease-free survival rates were 77.5% for intra-arterially treated and 33.0% for other patients in stage IIIa, and 70.5% for intra-arterially treated and 38.1% for other patients in stage IIIb. Five-year overall survival rates were 94.4% for intra-arterially treated and 61.7% for other patients in stage IIIa, and 90.9% for intra-arterially treated and 56.3% for other patients in stage IIIb. Ten-year overall survival rates in stage IIIb were 90.9% for treated and 22.5% for other group patents. All differences were statistically significant (p<0.05). Good histologic response to intra-arterial therapy was seen in 75% of the primary tumors and 71% of involved lymph nodes. Neoadjuvant intra-arterial therapy with hormonal therapy yielded better survival rates than no intra-arterial therapy or our previous intra-arterial regimen.

Administration, Oral↗