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Biomedical subjects

N Okimoto

Publications and source records attributed to N Okimoto.

At least 37 records · Page 2Linked to original sources
PubMed2000

Uncoupling between bone formation and resorption in ovariectomized rats with chronic cadmium exposure.

Osteoporosis, osteomalacia, and pathological fractures are characteristic features of Itai-Itai disease. The mechanisms of bone damage caused by cadmium (Cd) exposure have not been fully clarified. We investigated skeletal changes in ovariectomized rats with chronic Cd exposure, using bone histomorphometry and mechanical tests. Female Sprague-Dawley rats at the age of 8 weeks were ovariectomized. Eight weeks after ovariectomy, the rats were divided into two groups: Cd-OVX group (n = 15), ovariectomized rats given cadmium chloride (CdCl(2), 0.18 mg/rat) ip three times a week for 28 weeks; Cont-OVX group (n = 10), ovariectomized rats given distilled water alone for 28 weeks. Cd-OVX rats had a significant increase in serum concentration of intact osteocalcine and showed numerical but not significant increase in urinary excretion of deoxypyridinoline despite a significant decrease in glomerular filtration rate to 40% of the value in Cont-OVX rats. Bone mineral content (BMC) and density were significantly decreased in both the lumbar vertebral body and femur of Cd-OVX rats. Ultimate compressive load in the lumbar body and bending load in the midfemur were significantly lower in Cd-OVX rats than in Cont-OVX rats but the differences were not demonstrated when the values were corrected for BMC. Structural moduli in the lumbar vertebral body and the midfemur were not different between the two groups. Cd-OVX rats showed significant decreases in the trabecular bone volume and trabecular number with increased values in the indices of bone formation and resorption in the lumbar vertebral body cancellous bone in comparison with Cont-OVX rats. In the midfemur, Cd-OVX rats had significantly smaller cortical bone area than Cont-OVX rats but the moment of inertia was identical between the two groups. The indices of bone formation and resorption at endocortical surface of the midfemur were significantly increased in Cd-OVX rats over those in Cont-OVX rats, whereas the indices of bone formation at the periosteal surface were not different between the two groups. These data suggested that chronic Cd exposure exacerbated the uncoupling between bone formation and resorption in ovariectomized rats, which resulted in the osteopenia, structural changes of the bone, and decreased mechanical strength in ovariectomized rats with chronic Cd exposure.

Amino Acids↗
PubMed2000

Effects of resistance exercise training on mass, strength, and turnover of bone in growing rats.

To determine the effects of resistance exercise on mass, strength and local turnover of bone, 50 Sprague Dawley rats, 8 weeks of age, were assigned to five groups: a baseline control and two groups of sedentary and exercising rats. The trunk of the rats was kept upright during electrically stimulated jumping exercise for 1 h every other day. In 4 weeks, the trabecular mineralizing surface per bone surface (MS/BS), bone formation rate per bone surface (BFR/BS) and the compression load of the lumbar body increased and the number of osteoclasts decreased, but bone mineral density (BMD) and structure did not increase. In the mid femur, the cross-sectional area, the cortical bone area, the moment of inertia, the periosteal MS/BS, BFR/BS and the bending load increased in the exercise group. In 8 weeks, the increases in BMD, structure and load values were significant in both the lumbar and mid femur. At both 4 and 8 weeks, the MS/BS for the endocortical surface of mid femur were not increased and mineral apposition rate (MAR) remained reduced. These results show that jumping exercise increases the mass and strength of the lumbar vertebrae and mid femur by stimulating bone formation and accelerates cortical drift by both increasing periosteal bone formation and reducing the endocortical MAR.

Animals↗
PubMed2000

A comparison of resistance and aerobic training for mass, strength and turnover of bone in growing rats.

To determine the effects of resistance versus aerobic exercise on the mass, strength and turnover of bone. thirty Sprague Dawley rats (4 weeks of age) were assigned to one of three experimental groups: sedentary, running or jumping. In the jumping group, the trunk was kept upright during electrically stimulated jumping exercise for 1 h every other day. The running rats ran at speeds of 24 m/min for 1 h every other day. After 4 weeks, the jumping rats exhibited increases in the mass and strength of the lumbar vertebrae and of the mid-diaphysis of the femur (mid-femur), and increases in the cross-sectional morphology of these bones: the trabecular bone volume per bone surface, the trabecular thickness, the trabecular bone formation rate per bone surface (BFR/BS). In addition, they exhibited reduced trabecular separation and the area of osteoclast surface per bone surface. The running and sedentary rats showed no such changes. With regard to the mid-femur, in both the jumping and running rats the periosteal BFR/BS was increased. However, only the jumping rats showed a reduction in the BFR/BS at the endocortical surface. These results suggest that resistance exercise accelerates cortical drift and increases the bone mass and strength by stimulating bone formation more efficiently than does aerobic exercise.

Animals↗
PubMed2000

Activin increases bone mass and mechanical strength of lumbar vertebrae in aged ovariectomized rats.

Activin is a member of the transforming growth factor-beta superfamily and is thought to be involved in the regulation of bone formation due to its presence in bone tissue and its osteogenic activity both in vitro and in vivo. We recently found that systemic administration of activin increased both tibial bone mass and mechanical strength in young growing rats. The present study investigated the effects of activin in aged ovariectomized (ovx) rats. Twelve-month-old Fischer rats were ovariectomized and maintained for 10 months. Recombinant human activin A (activin) or human parathyroid hormone 1-34 (PTH) was administered intramuscularly three times a week for 12 weeks. Activin (1 and 5 microg/kg) markedly increased lumbar vertebral bone mineral content and bone mineral density. Activin also increased the mechanical strength of the vertebral body, which was highly correlated to the bone mineral density of the vertebral body. The maximal response in bone mass and strength was observed at 1 microg/kg of activin, which was approximately equal to that induced by PTH at 40 microg/kg. Peripheral quantitative computed tomography revealed that activin enlarged the cross-sectional size of the vertebrae without changing the foramen area, indicating its effects on cortical shells. Histomorphometric analysis of cancellous bone of vertebral body in similar experiment showed that activin (3 microg/kg) increased bone volume and the mineralizing surface, although its effects were less than PTH. The present results indicate that low doses of activin are effective against vertebral bone loss in aged ovx rats.

Activins↗
PubMed2000

Skeletal changes in rats bearing mammosomatotrophic pituitary tumors: a model of acromegaly with gonadal dysfunction.

Growth hormone (GH) exerts potent effects on bone metabolism, resulting in an increased bone formation in animals and humans. Acromegaly has been associated with increased bone turnover, whereas the net effect of the increased bone metabolism has been obscured because patients with acromegaly are often associated with hypogonadism. We investigated changes in cortical and cancellous bone in adult rats implanted mammosomatotrophic pituitary tumor cells (GH3) as a model of acromegaly with gonadal dysfunction. Acromegaly model rats were prepared by implanting GH3 cells into female Wistar-Furth rats at 17 weeks of age. At 28 weeks of age, GH3-bearing rats (GH rats) showed very high serum GH levels and a moderate increase in serum prolactin levels, resulting in low circulating estradiol levels. The GH rats showed significant increases in body weight and in length and volume of both the femur and vertebral body. Bone mineral content values of either the midfemur or the whole lumbar body were significantly greater in the GH rats compared with littermate controls, while the areal bone mineral density values of the respective bones were not different between the two groups. The parameters of mechanical strength of the femur were significantly larger in the GH rats than in controls, whereas those of the lumbar vertebral body cylinder specimen were not different between the two groups. Respective normalized mechanical parameters of the femur and the vertebral body were the same in the GH rats as in controls. In the midfemur, the GH rats showed a significant increase in the total cross-sectional area without influencing the bone marrow area, resulting in an increase in the cortical bone area and the moment of inertia compared with controls. The indices of periosteal bone formation in the midfemur were greater in the GH rats compared with controls, but the endocortical bone formation and resorption were not different between the two groups. In the vertebral body cancellous bone, the GH rats had an increase in bone turnover rate, whereas the structural parameters were not different between the two groups. These results from GH3-bearing rats demonstrate that an excess of GH increases cortical bone mass in rats accompanied with estrogen deficiency, while no large effect on vertebral body cancellous bone mass is seen.

Acromegaly↗
PubMed2000

[Clinical analysis of nursing home-acquired pneumonia in a community hospital].

To clarify the characteristic features of nursing home-acquired pneumonia in our community hospital, we performed a clinical analysis of 86 patients with nursing home-acquired pneumonia. The patients were divided into young and elderly groups. In the young group cerebral palsy was the underlying disease. In the elderly group, it was cerebrovascular attack. Although there were no differences in ADL, the nutritional condition of the young group was comparatively good, the isolated microorganism consisted of mostly Mycoplasma pneumoniae and the prognosis was good. The elderly group where the nutritional condition was poor, the patients were detected by non-respiratory symptoms and risk factors such as obvious episodes of aspiration led us to be concerned about the risk factors for nursing home-acquired pneumonia. The microorganism isolated from the sputum of the elderly group was frequently a multi-drug resistant microorganism such as Methicillin-resistant Staphylococcus aureus (MRSA) and polymicrobial infection. Their prognosis was poor despite treatment with multiple antibiotics. In the comparative study between survivors and non-survivors in the elderly group, risk factors such as hypotension, consciousness disturbance, the extension of infiltration shadows, respiratory failure, multiple organ failure and metabolic acidosis were influenced for the prognosis, but the isolated microorganisms and the antimicrobial agents were not concerned.

Adolescent↗
PubMed2000

[Clinical analysis of community-acquired pneumonia requiring hospitalization in a community hospital--comparison of elderly and non-elderly patients].

A comparative study of 890 patients with community-acquired pneumonia requiring hospitalization in a community hospital was performed. The patients were divided into an elderly patient group and a non-elderly patient group. The elderly patients with community-acquired pneumonia exhibited frequent atypical symptoms such as dyspnea, consciousness disturbance and complication of shock, and also were frequently in a poor nutritional condition. The causative microorganism was isolated in 40.8% of the elderly patients and in 44.0% of the non-elderly patients. Polymicrobial agents were detected frequently in the elderly patients. Streptococcus pneumoniae (19.4%), MSSA (16.8%), Klebsiella pneumoniae (15.1%) and Haemophilus influenzae (15.0%) were frequently isolated from the sputum of the elderly patients, while Mycoplasma pneumoniae (25.2%), H. influenzae (15.0%), S. pneumoniae (12.2%) and MSSA (10.2%) were frequently isolated from that of the non-elderly patients. Regarding treatment with antibiotics, therapy with a single antibiotic therapy, such as cephem or carbapenem was carried out for the elderly patients, while new quinolone or tetracycline was administered to the non-elderly patients. Although the treatment with antibiotics was adequate according to the guidelines of the American Thoracic Society, the prognosis was poor; i.e.) in the elderly patients an efficacy rate of 74.3% and a mortality rate of 9.5%. In the non-elderly patients, the prognosis was good; i.e.) an efficacy rate of 88.0% and a mortality rate of 1.7%. These results suggest that the most important factors affecting the prognosis were the general condition of elderly patients and delay in an adequate diagnosis and treatment because of atypical clinical findings.

Aged↗
PubMed2000

[Viral infection related to the appearance of acute bacterial respiratory tract infections].

To investigate what viruses are related to acute bacterial respiratory tract infections, we prospectively evaluated 113 cases with respiratory tract infections (always accompanying by purulent sputum) experienced between July 1998 and March 2000. Acute viral infections were detected in 25 cases (22%); 10 cases of influenza A virus and 6 cases of respiratory syncytial (RS) virus. The epidemiology of the influenza A virus and RS virus was mainly identified as from December to February in both winter seasons. A bacteriological examination of sputum cultures isolated 12 cases of Streptococcus pneumoniae and 10 cases of Haemophilus influenzae during the same periods and mixed infections of both viruses and bacteria were recognised in 16 cases (14%). These results suggest a significantly high percentage of mixed infections of both viruses and bacteria. However, it was unknown whether the patients with acute bacterial respiratory infections had been infected with viruses prior to the bacterial infections. The frequency of appearance of respiratory tract infections tended to increase with the seasonale epidemiology of viral infections.

Acute Disease↗
PubMed2000

[Transitional pattern of the clinical features of patients with pulmonary tuberculosis in a community hospital].

To determine changes in the clinical features of recent patients with pulmonary tuberculosis in a community hospital without restricted tuberculosis wards, the clinical findings of 112 patients with pulmonary tuberculosis (containing miliary tuberculosis) during the past 15 years were compared by dividing the patients into three groups, each encompassing a five-year period. Recently, the number of patients with pulmonary tuberculosis was found to be increasing in a community hospital. In particular, the percentages of elderly patients and smear positive patients have increased. However, because of the improving awareness on tuberculosis, we have diagnosed TB cases correctly on admission and tended to perform the appropriate treatment. The comparative study between pulmonary tuberculosis patients diagnosed at the outpatients department and diagnosed after admission indicated that the patients diagnosed after admission showed pneumonia-like infiltrative shadows without cavity formation and lower smear positivity for tubercle. Fortunately, resistance to antituberculous drugs of isolated tubercle bacilli in our community hospital has not yet increased and the prognosis of the cases proved to be good when the appropriate treatment was performed at an early stage.

Adolescent↗
PubMed2000

[Desensitization therapy for antituberculous drugs].

We retrospectively evaluated the effectiveness of desensitization therapy for antituberculous drugs (Rifampicin and Isoniazid) in 28 cases (29 episodes) with adverse reactions to these drugs. Desensitization therapy for RFP was performed in 23 cases (24 episodes) with administration of a first dose of 1-150 mg and a final dose of 300-450 mg for 1-29 days. The success rate of this therapy was 79% (19 of 24 episodes). Desensitization therapy for INH was performed in 12 cases with administration of a first dose of 2.5-100 mg and a final dose of 200-400 mg for 3-25 days. The success rate of this therapy was 83% (10 of 12 cases). Based on a comparative study of cases between successful and unsuccessful desensitization to RFP and INH it was concluded that there were no significant differences with regard to allergic history, adverse effects and their periods of appearance, the first dose and final dose of administration and the interval of administration, starting periods of the desensitization therapy and the periods of appearance of adverse effects due to this therapy. We evaluated desensitization therapy for two antituberculous drugs (RFP and INH) for tuberculous patients for whom the use of such drugs was restricted because of adverse effects, and we found it is a useful treatment, showing a high rate of success (80%).

Adolescent↗
PubMed2000

[Desensitization therapy for allergic reactions of antituberculous drugs--evaluation of desensitization therapy according to the guideline of the Japanese Society for Tuberculosis].

We prospectively evaluated the effectiveness of desensitization therapy for cases showing side-effects to antituberculous drugs (Isoniazid and Rifampicin) according to the guideline proposed by the Treatment Committee of the Japanese Society for Tuberculosis. Nineteen patients (23-88 years old, male 9, female 10) who had experienced adverse effects after receiving antituberculous drugs and underwent desensitization therapy between August 1998 and March 2000 were studied. Underlying diseases were 14 cases of pulmonary tuberculosis, 2 cases of cervical tuberculous lymphadenitis, 1 case of pulmonary atypical mycobacteriosis, 1 case of pulmonary tuberculosis and tuberculous pleuritis, 1 case of pulmonary tuberculosis and tuberculous lymphadenitis. The regimens of treatment for tuberculosis were INH + RFP + EB in 8 cases, INH + RFP + EB + PZA in 7 cases, INH + RFP + SM in 2 cases, INH + RFP + SM + PZA in 1 case, and INH + RFP in 1 case. Adverse reactions were 8 cases of eruption, 7 cases of drug fever, 3 cases of drug fever and eruption, and 1 case of drug fever and cervical lymphadenopathy. The causative drugs suggested from DLST or the clinical course were RFP in 17 cases and INH in 8 cases. The clinical effect of desensitization therapy for these antituberculous drugs was good in 14 out of the 17 cases (82%) for RFP, and in 6 out of 8 cases (75%) for INH. The effectiveness rate of the present desensitization therapy according to the guideline of the Japanese Society for Tuberculosis was almost equal to that of previous desensitization therapy, and the clinical results were almost same in present and previous studies despite the different methods of administration of the antituberculous drugs.

Adult↗
PubMed1999

Large-dose ascorbic acid administration suppresses the development of arthritis in adjuvant-infected rats.

We performed animal experiments to test the hypothesis that active oxygen species (AOS) play a major role in adjuvant-induced arthritis in rats and to determine whether large-dose ascorbic acid administration would suppress the development of arthritis, reducing the level of damaging AOS in the same animal model. Arthritis was induced in male Lewis rats by adjuvant injection into the base of the tail. Ascorbic acid at doses of 0.5, 1.0, and 2.0 g/kg body weight (BW) was injected intraperitoneally twice each week for 3 weeks (9 rats per group). The BW, hind paw edema, and arthritis score of the extremities were monitored during the period. On day 21, synovial tissues obtained from the ankle joints were examined histologically and for the activity of superoxide dismutase (SOD). The SOD activity in the red blood cells (RBC) was also measured. The arthritic control rats showed significant increases in paw volume and arthritis score from day 11. These changes were dose-dependently reduced by ascorbic acid administration. The infiltration of inflammatory cells into the synovial tissues was markedly decreased by ascorbic acid. The increases in SOD activities produced by the adjuvant injection were significantly reduced in both the synovium and the RBC at ascorbic acid doses of 1.0 and 2.0 g/kg BW. In conclusion, large-dose ascorbic acid administration reduced the increases in hind paw inflammatory edema, arthritis in the extremities, and infiltration of the inflammatory cells into the synovial tissue in the adjuvant-induced arthritis rats. Since these anti-arthritic effects were associated with a decrease in SOD activities in both the synovium and RBC, the decrease in SOD activity could be one of the mechanisms underlying the suppressive effects of large-dose ascorbic acid on the development of arthritis in this animal model, inhibiting the damaging AOS.

Animals↗
PubMed1999

[Clinical analysis of the prognosis of severe pneumonia requiring mechanical ventilation].

To determine which factors are important in predicting the outcome of patients with severe pneumonia requiring mechanical ventilation, we compared 43 surviving pneumonic patients with 37 non-surviving pneumonic patients. The following results were obtained. The following characteristics were noted in the non-surviving patients as compared with surviving patients; 1. a worsening of performance status in the background, 2. presence of physical signs such as hypotension and trachycardia, 3. abnormal laboratory data such as leukocytosis, lymphocytopenia, hypoalbuminemia, hepatorenal dysfunction and metabolic acidosis, 4. presence of massive pulmonary infiltrations on chest roentgenograms, 5. a prevalence of resistant microorganisms for many antibiotics such as MRSA (Methicillin resistant Staphylococcus aureus). These results suggest that the most important factor affecting the prognosis of patients with severe pneumonia requiring mechanical ventilation may by the condition of the host and of the microorganisms rather than antibiotic treatment.

Aged↗
PubMed1999

[Three cases of pneumonia due to mixed infection of bacteria and Mycoplasma pneumoniae].

We reported three cases of pneumonia due to mixed infection of bacteria (2 cases: Streptococcus pneumoniae, 1 case: methicilline-sensitive Stapholococcus aureus) and Mycoplasma pneumoniae. Increased serum antibody titers of M. pneumoniae were noted in all cases. They were a 36-year-old-female with bronchial asthma, a 74-year-old-male with old pulmonary tuberculosis and a 82-year-old-male with chronic bronchitis. All cases had fever, productive cough with purulent sputum and coarse crackle by auscultation. Leukocytosis was noted in 2 cases. Chest X-ray films showed dense consolidation in all cases, 2 cases were cured by administration of cephems and 1 case was cured by administration of carbapenems and minocycline.

Adult↗
PubMed1999

[Clinical analysis of pneumonia in the elderly in a community hospital--comparison of community-acquired pneumonia and nosocomial pneumonia].

We experienced 530 elderly cases with pneumonia among 930 patients with pneumonia in Kawasaki Medical School Kawasaki Hospital between April 1986 and September 1998. Clinical analysis of all these patients and a comparison of one group consisting of 418 patients with community-acquired pneumonia and another group composed of 112 patients with nosocomial pneumonia were performed. In all of the elderly patients with pneumonia, respiratory symptoms and inflammatory findings were less frequent, but were frequent for those in poor general and nutritional condition. The causative microorganism was isolated in 42% of these patients. Streptococcus pneumoniae, MSSA and Klebsiella pneumoniae were frequently isolated from the sputum of the patients with community-acquired pneumonia, while Methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, Methicillin-sensitive Staphylococcus aureus (MSSA) were frequently isolated from that of nosocomial pneumonia patients. Mycoplasma pneumoniae, Chlamydia pneumoniae and some viruses were less frequent for patients in both groups. Although many intravenous antibiotics, such as cephem or carbapenem were administered to patients in both groups, the prognosis was relatively good for those with community acquired pneumonia but was extremely poor for those with nosocomial pneumonia despite mechanical ventilation or steroid pulse therapy for many patients.

Aged↗