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Biomedical subjects

Jun Iwamoto

Publications and source records attributed to Jun Iwamoto.

At least 37 records · Page 2Linked to original sources

Prevention and treatment of corticosteroid-induced osteoporosis.

Osteoporosis is one of the most serious complications of corticosteroid treatment. Loss of bone mineral density (BMD) and fractures occur early in the course of corticosteroid treatment, and thus early recognition of fracture risk and effective intervention based on evidence-based-medicine (EBM) are needed. A study of meta-analysis representing the highest level in a hierarchy of evidence showed that when the outcome measure of interest was limited to changes in lumbar spine BMD, bisphosphonates were the most effective of the agents studied in comparison with no therapy or treatment with calcium, and were also more efficacious than either vitamin D or calcitonin; the efficacy of bisphosphonates was enhanced when used in combination with vitamin D. Randomized controlled trials (RCTs) representing the second level in a hierarchy of evidence showed that bisphosphonates stabilized BMD not only in the lumbar spine, but also in the hip, and that parathyroid hormone (PTH) markedly increased lumbar spine BMD. According to the EBM, bisphosphonates and possibly PTH are suggested to be the most efficacious for preserving BMD. The efficacy of these agents in reducing the incidence of vertebral fractures in patients exposed to corticosteroids remains to be established in meta-analysis studies, although some RCTs have demonstrated the anti-fracture effects of etidronate, alendronate, and risedronate in the spine. Further RCTs of fracture prevention conducted on a large number of patients and their meta-analysis are needed to confirm the efficacy of bisphosphonates, PTH, or other agents in preventing vertebral and nonvertebral fractures.

Adrenal Cortex Hormones↗

Low-dose vitamin D prevents muscular atrophy and reduces falls and hip fractures in women after stroke: a randomized controlled trial.

OBJECTIVE: Vitamin D supplementation is suggested to reduce the risk of falls among ambulatory or institutionalized elderly subjects. The present study was undertaken to address the reduced risk of falls and hip fractures in patients with long-standing stroke by vitamin D supplementation. METHODS: Ninety-six elderly women with poststroke hemiplegia were followed for two years. Patients were randomly assigned to one of the two groups, and 48 patients received 1,000 IU ergocalciferol daily, and the remaining 48 received placebo. The number of falls per person and incidence of hip fractures were compared between the two groups. Strength and tissue ATPase of skeletal muscles on the nonparetic side were assessed before and after the study. RESULTS: At baseline, serum 25-hydroxyvitamin D levels were in the deficient range (<10 ng/ml) in all patients; and vitamin D treatment enhanced serum 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D levels. Vitamin D treatment accounted for a 59% reduction in falls (95% CI, 28-81%; p = 0.003). There were increases in the relative number and size of type II muscle fibers and improved muscle strength in the vitamin D-treated group. Hip fractures occurred in 4 of 48 placebo group and 0 in 48 vitamin D2 group during the 2-year study period (log-rank, p = 0.049). CONCLUSION: Vitamin D may increase muscle strength by improving atrophy of type II muscle fibers, which may lead to decreased falls and hip fractures.

Accidental Falls↗

Efficacy of oral etidronate for skeletal diseases in Japan.

Etidronate is an oral bisphosphonate compound that is known to reduce bone resorption through the inhibition of osteoclastic activity. The efficacy of etidronate for involutional (postmenopausal and senile) and glucocorticoid-induced osteoporosis, as well as that for other skeletal diseases, was reviewed in Japanese patients. Cyclical etidronate treatment (200 mg or 400mg/day for 2 weeks about every 3 months) increases the lumbar bone mineral density (BMD) in patients with involutional osteoporosis and prevents incident vertebral fractures in patients with glucocorticoid-induced osteoporosis. The losses of the lumbar BMD in patients with liver cirrhosis and the metacarpal BMD in hemiplegic patients after stroke are prevented, and the lumbar BMD is possibly increased, preventing fragile fractures in adult patients with osteogenesis imperfecta type I. Furthermore, proximal bone resorption around the femoral stem is reduced and some complications may be prevented in patients who undergo cementless total hip arthroplasty. Oral etidronate treatment may also help to transiently relieve metastatic cancer bone pain followed by a decrease in abnormally raised bone resorption in patients with painful bone metastases from primary cancer sites, such as the lung, breast and prostate. Thus, oral etidronate treatment is suggested to be efficacious for osteoporosis, as well as other skeletal diseases associated with increased bone resorption, in Japanese patients. Randomized controlled trials needed to be conducted on a large number of patients to confirm these effects.

Administration, Oral↗

Amelioration of osteoporosis and hypovitaminosis D by sunlight exposure in hospitalized, elderly women with Alzheimer's disease: a randomized controlled trial.

UNLABELLED: In a random and prospective study, Alzheimer's disease (AD) patients were assigned to regular sunlight exposure (n = 132) or sunlight deprivation (n = 132) and followed for 1 year. Serum 25-OHD level increased by 2.2-fold in the sunlight-exposed group. Eleven patients sustained fractures in the sunlight-deprived group, and three fractures occurred among the sunlight-exposed group (p = 0.0362; odds ratio = 3.7). INTRODUCTION: A high incidence of fractures, particularly of the hip, represents an important problem in patients with Alzheimer's disease (AD), who are prone to falls and have osteoporosis. We previously showed that 25-hydroxyvitamin D (25-OHD) deficiency caused by sunlight deprivation with compensatory hyperparathyroidism causes reduced BMD in elderly women with AD. This study was undertaken to address the possibility that sunlight exposure with calcium supplementation may maintain BMD and reduce the incidence of nonvertebral fractures in elderly women with AD. MATERIALS AND METHODS: In a random and prospective study, AD patients were assigned to regular sunlight exposure (n = 132) or sunlight deprivation (n = 132) and followed for 1 year. BMD of the second metacarpal bone was measured using a computed X-ray densitometer (CXD). The CXD method measures BMD and cortical thickness at the middle of the second metacarpal bone on a radiogram of the hand and an aluminum step wedge as a standard (20 steps; 1 mm/step). Incidence of nonvertebral fractures in the two patient groups during the 1-year follow-up period was assessed. RESULTS AND CONCLUSION: At baseline, average hospitalization period was 1.7 years in both groups, and activity of daily living (ADL) was decreased. Patients of both groups showed vitamin D deficiency caused by sunlight deprivation and decreased dietary intake of vitamin D with compensatory hyperparathyroidism. The exposed group patients were exposed to sunlight (3615 minutes/year). BMD increased by 2.7% in the sunlight-exposed group and decreased by 5.6% in the sunlight-deprived group (p < 0.0001). Serum 25-OHD level increased from 24.0 to 52.2 nM in the sunlight-exposed group. Eleven patients sustained fractures in the sunlight-deprived group, and three fractures occurred among the sunlight-exposed group (p = 0.0362; odds ratio = 3.7). Sunlight exposure can increase the BMD of vitamin D-deficient bone by increasing 25-OHD concentration and lead to the prevention of nonvertebral fractures.

25-Hydroxyvitamin D 2↗

Risedronate therapy for prevention of hip fracture after stroke in elderly women.

BACKGROUND: There is a high incidence of hip fractures in patients with hemiplegic stroke. Bone mineral density (BMD) is decreased in the hemiplegic side in patients after stroke, correlating with the degree of paralysis and of hypovitaminosis D. OBJECTIVE: To evaluate the efficacy of risedronate in reducing the severity of osteoporosis and in decreasing the risk of hip fractures in elderly women following an acute stroke. METHODS: This was a 12-month, randomized, double blind, placebo-controlled trial. In a prospective study of stroke patients, 187 patients received a daily dose of 2.5 mg risedronate for 12 months, and the remaining 187 received placebo. Incidence of hip fracture was compared between the two groups at the endpoint of the study. RESULTS: Seven patients sustained hip fractures on the hemiplegic side in the placebo group, and one hip fracture occurred in the risedronate group (p = 0.0360; OR = 7.0). BMD increased by 1.5% and decreased by 4.9% in the risedronate group and placebo group (p < 0.0001). Urinary deoxypyridinoline, a bone resorption marker, decreased by 53.4% in the risedronate group and increased by 35.8% in the placebo group. CONCLUSION: Treatment with risedronate increases bone mineral density in elderly women following an acute stroke and prevents hip fractures.

Accidental Falls↗

Effect of folate and mecobalamin on hip fractures in patients with stroke: a randomized controlled trial.

CONTEXT: Stroke increases the risk of subsequent hip fracture by 2 to 4 times. Hyperhomocysteinemia is a risk factor for both ischemic stroke and osteoporotic fractures in elderly men and women. Treatment with folate and mecobalamin (vitamin B12) may improve hyperhomocysteinemia. OBJECTIVE: To investigate whether treatment with folate and vitamin B12 reduces the incidence of hip fractures in patients with hemiplegia following stroke. DESIGN, SETTING, AND PATIENTS: A double-blind, randomized controlled study of 628 consecutive patients aged 65 years or older with residual hemiplegia at least 1 year following first ischemic stroke, who were recruited from a single Japanese hospital from April 1, 2000, to May 31, 2001. Patients were assigned to daily oral treatment with 5 mg of folate and 1500 microg of mecobalamin, or double placebo; 559 completed the 2-year follow-up. MAIN OUTCOME MEASURE: Incidence of hip fractures in the 2 patient groups during the 2-year follow-up. RESULTS: At baseline, patients in both groups had high levels of plasma homocysteine and low levels of serum cobalamin and serum folate. After 2 years, plasma homocysteine levels decreased by 38% in the treatment group and increased by 31% in the placebo group (P<.001). The number of hip fractures per 1000 patient-years was 10 and 43 for the treatment and placebo groups, respectively (P<.001). The adjusted relative risk, absolute risk reduction, and the number needed to treat for hip fractures in the treatment vs placebo groups were 0.20 (95% confidence interval [CI], 0.08-0.50), 7.1% (95% CI, 3.6%-10.8%), and 14 (95% CI, 9-28), respectively. No significant adverse effects were reported. CONCLUSION: In this Japanese population with a high baseline fracture risk, combined treatment with folate and vitamin B12 is safe and effective in reducing the risk of a hip fracture in elderly patients following stroke.

Aged↗

Amelioration by mecobalamin of subclinical carpal tunnel syndrome involving unaffected limbs in stroke patients.

Our previous study showed that overuse of the nonparetic hand and wrist of the nonparetic side following stroke result in significantly more abnormal on the nonparetic side than on the hemiparetic side in terms of electrophysiologic indices of median nerve function. The purpose of this study was to evaluate the effects of the orally administered mecobalamin, an analogue of vitamin B12, for carpal tunnel syndrome (CTS) in the nonparetic side in patients following stroke. In a randomized open label and prospective study of stroke patients, 67 received of 1500 mug mecobalamin daily for 2 years, and the remaining 68 (untreated group) did not. At baseline, sensory nerve conduction velocity, motor nerve conduction velocity, sensory nerve action potentials (SNAP) at the wrist, palm-to-wrist distal sensory latency, palm-to-wrist SNAP, motor nerve conduction velocity compound motor action potentials, and distal motor latency of median nerve were significantly more abnormal on the nonparetic side than on the hemiparetic side or in controls. Before the treatment 21 patients (31%) of untreated and 20 patients (30%) of treated group met electrophysiologic criteria for CTS. Sensory impairment of the nonparetic side had lessened in the treated group. After 2 years, all electrophysiologic indices of nonparetic side were significantly improved in the treated group compared with those in the untreated group. The improvement from baseline of electrophysiologic parameters in sensory nerve in the treated group was greater than the improvement measured in motor nerve. There were no side effects. Oral mecobalamin treatment is a safe and potentially beneficial therapy for CTS in stroke patients.

Action Potentials↗

Abnormal bone and calcium metabolism in immobilized Parkinson's disease patients.

To elucidate the influence of immobilization-induced hypercalcemia on bone metabolism in Parkinson's disease (PD), we measured serum biochemical indexes and bone mineral density (BMD) in the second metacarpals of 142 elderly PD patients and 99 age-matched healthy controls. Serum concentrations of 25-hydroxyvitamin D (25-OHD), 1,25-dihydroxyvitamin D (1,25-[OH](2)D), ionized calcium, intact parathyroid hormone (PTH), and intact bone Gla protein (BGP) were measured. Urinary deoxypyridinoline (D-Pyr) was also measured. Increased serum calcium levels (mean, 1.27 mmol/L) were observed in PD patients, and the levels correlated negatively with the Unified Parkinson's Disease Rating Scale III (UPDRS III), indicating the presence of immobilization-induced bone resorption with resultant hypercalcemia. Decreased serum concentrations of 1,25-[OH](2)D (mean, 88.7 pmol/L) and 25-OHD (mean, 29.7 nmol/L) were noted. Serum PTH was decreased (mean, 25.2 ng/L). Serum BGP was decreased while urinary D-Pyr concentration elevated. A negative correlation was observed between 1,25-[OH](2)D levels and serum calcium or UPDRS III (P < 0.0001). In disabled PD patients, immobilization-induced hypercalcemia may inhibit secretion of PTH, which in turn suppresses 1,25-[OH](2)D production. 25-OHD insufficiency may also contribute to decreased 1,25-[OH](2)D. These abnormalities may be corrected by the suppression of bone resorption with bisphoshonate, and supplementations of calcium and vitamin D should be avoided in these patients.

Aged↗

Effect of whole-body vibration exercise on lumbar bone mineral density, bone turnover, and chronic back pain in post-menopausal osteoporotic women treated with alendronate.

BACKGROUND AND AIMS: Exercise may enhance the effect of alendronate on bone mineral density (BMD) and reduce chronic back pain in elderly women with osteoporosis. The aim of this study was to determine whether whole-body vibration exercise would enhance the effect of alendronate on lumbar BMD and bone turnover, and reduce chronic back pain in postmenopausal women with osteoporosis. METHODS: Fifty post-menopausal women with osteoporosis, 55-88 years of age, were randomly divided into two groups of 25 patients each: one taking alendronate (5 mg daily, ALN) and one taking alendronate plus exercise (ALN+EX). Exercise consisted of whole-body vibration using a Galileo machine (Novotec, Pforzheim, Germany), at an intensity of 20 Hz, frequency once a week, and duration of exercise 4 minutes. The study lasted 12 months. Lumbar BMD was measured by dual energy X-ray absorptiometry (Hologic QDR 1500W). Urinary cross-linked N-terminal telopeptides of type I collagen (NTX) and serum alkaline phosphatase (ALP) levels were measured by enzyme-linked immunosorbent assay and standard laboratory techniques, respectively. Chronic back pain was evaluated by face scale score at baseline and every 6 months. RESULTS: There were no significant differences in baseline characteristics, including age, body mass index, years since menopause, lumbar BMD, urinary NTX and serum ALP levels, or face scale score between the two groups. The increase in lumbar BMD and the reduction in urinary NTX and serum ALP levels were similar in the ALN and ALN+EX groups. However, the reduction in chronic back pain was greater in the ALN+EX group than in the ALN group. CONCLUSIONS: The results of this study suggest that whole-body vibration exercise using a Galileo machine appears to be useful in reducing chronic back pain, probably by relaxing the back muscles in post-menopausal osteoporotic women treated with alendronate.

Accidental Falls↗

Early changes in urinary cross-linked N-terminal telopeptides of type I collagen level correlate with 1-year response of lumbar bone mineral density to alendronate in postmenopausal Japanese women with osteoporosis.

The purpose of this study was to determine whether early changes in the urinary levels of cross-linked N-terminal telopeptides of type I collagen (NTX) during alendronate treatment would be correlated with the 1-year response of lumbar bone mineral density (BMD) in postmenopausal Japanese women with osteoporosis. One hundred five postmenopausal women with osteoporosis, aged 54-88 years, were treated with alendronate (5 mg daily) for 12 months. The urinary NTX levels were measured by enzyme-linked immunosorbent assay at the baseline and at 3, 6, and 12 months, and lumbar (L1-L4) BMD was measured by dual-energy X-ray absorptiometry using the Hologic QDR 1500W equipment at the baseline and at 12 months. The mean percent reduction in urinary NTX level at 3, 6, and 12 months was 36.8%, 49.5%, and 49.0%, respectively, the extent of reduction at 6 and 12 months being greater than that at 3 months, and the mean percent increase of the lumbar BMD at 12 months was 8.2%. Single regression analysis showed a significant correlation between the percent reductions in the urinary NTX level at 3, 6, and 12 months of treatment and the percent increase of the lumbar BMD at 12 months (r = 0.200, P < 0.05; r = 0.341, P < 0.001; and r = 0.338, P < 0.001, respectively). Thirty percent of the patients were labeled as poor responders at 3 months, with the reduction in the urinary NTX level being less than the minimum significant change (MSC); 61% of these patients showed a greater reduction in the urinary NTX level, exceeding the MSC, at 6 months. These results suggest that the changes in the urinary NTX levels at 3 and 6 months after the start of alendronate treatment at the dose of 5 mg daily may be correlated with the 1-year response of the lumbar BMD in postmenopausal Japanese women with osteoporosis. In other words, the greater the reduction of the urinary NTX level at 3 and 6 months after the start of alendronate treatment, the greater can be the expected increase of the lumbar BMD after 12 months of treatment. In this study, 70% of the patients were good responders, who showed a reduction of the urinary NTX level exceeding the MSC at 3 months. Among the remaining 30% poor responders, about 60% showed satisfactory reduction of the urinary NTX level, exceeding the MSC, at 6 months after the start of treatment with alendronate.

Aged↗

Effects of risedronate on femoral bone mineral density and bone strength in sciatic neurectomized young rats.

Immobilization induces a rapid loss of bone density and bone strength in rats. The purpose of the present study was to examine the effects of risedronate (Ris) on the femoral bone density and bone strength of sciatic neurectomized young rats. Forty male Sprague-Dawley rats, 6 weeks of age, were randomized by the stratified weight method into the following four treatment groups of 10 rats each: sham-operation, bilateral sciatic neurectomy (NX), NX + low-dose Ris (0.25 mg/kg/day, orally), and NX + high-dose Ris (0.5 mg/kg/day, orally). After 8 weeks of feeding, the volumetric bone mineral density (vBMD) and stress strain index (SSI) of the femoral distal metaphysis and middiaphysis of the rats were measured by peripheral quantitative computed tomography. The mechanical properties of the femoral distal metaphysis and middiaphysis were measured by the compression and three-point bending tests, respectively. The femoral length was also measured. As compared with the findings in the sham-operated controls, NX resulted in a loss of femoral length, cancellous vBMD, SSI, maximum load, stiffness, and breaking energy of the femoral distal metaphysis; there was also loss of cortical thickness, SSI, maximum load, and stiffness of the femoral middiaphysis, with no significant effects on the cortical vBMD or breaking energy of the femoral middiaphysis. High-dose Ris increased the vBMD to values higher than those in the sham-operated controls, and prevented the loss of SSI, maximum load, and stiffness of the femoral distal metaphysis, while low-dose Ris prevented the loss of cancellous vBMD of the femoral distal metaphysis. Neither high- nor low-dose Ris affected any of the cortical bone parameters of the femoral middiaphysis, except for cortical thickness, or the femoral length. These findings suggest that Ris may prevent immobilization-induced loss of cancellous bone density and bone strength in a dose-dependent manner without interfering with bone growth, but has no apparent effects on the cortical bone in sciatic neurectomized young rats. The results of the present preclinical study should be taken into consideration prior to the commencement of Ris treatment for disabled children.

Animals↗

RETRACTED: Homocysteine as a predictive factor for hip fracture in elderly women with Parkinson's disease.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article is being retracted at the request of the Editor in Chief because of the stated concerns listed below. The article was accepted for publication by a previous editor and editorial board nearly 15 years ago, at a time when submissions and documentation were in paper form, prior to the transition of The American Journal of Medicine to a digital submission and review process. The records, including the original manuscript and peer reviewers' comments, are no longer extant and consequently we are unable to review the comments of the peer reviewers and the editors involved at that time. Nevertheless, the allegations of Grey et al. (as detailed in their Letter of Concern, published in the March 2018 issue of AJM, Volume 131, Issue 3, pages e107–e108; DOI: 10.1016/j.amjmed.2017.10.009) seem valid. A response by the Editor-in-Chief was also published in that issue. Therefore, given the documentation of Grey et al, the journal has concluded that this article should be considered as likely fraudulent and should not be quoted in the scientific literature in support of its conclusions. The article is severely compromised by wide-ranging and serious concerns about governance, ethics, authorship, implausible study conduct, implausible workload, discrepant participant numbers and treatment groups, impossible data, implausible data, implausible outcome data and discrepant methodology. The concerns are detailed in the afore-referenced letter of concern and can be summarized as follows: • It is stated that the study was approved by the Human Investigation Committee of the Futase Social Insurance Hospital, yet Futase Hospital did not have an ethics committee until 2010. • Given the size of the hospital and volume of clinics undertaken, it is highly unlikely that the stated number of participants could have been recruited within 3 months, or followed up as reported. • There are inconsistencies in the reported data. In Table 1 the mean ages of participants by quartiles of plasma homocysteine are 69.0, 70.6, 71.9, and 72.6 years. The corresponding mean years since menopause are 13.7, 14.6, 15.2, and 16.2 years, meaning that the average age of menopause is 55–57 years, implausibly older than the expected value of 50 years. The plasma homocysteine data in quartile 1 are incorrect. Among 50 women with a range of 6.1-9.0 μmol/L, the reported mean (standard deviation), 7.1 (2.5) μmol/L, is not possible. • In Table 3 the rate of hip fractures in the cohort (72 per 1000 patient-years) is implausibly high, being at least 3 to 4 times that reported in large observational studies of PD. The 51 incident hip fractures in 50 women in quartile 4 represents an astonishing hip fracture incidence of 227 per 1000 patient-years, yet only 6 women (3%) in this quartile were lost to follow-up (Table 1), and none was apparently treated with medications known to reduce fracture risk. The reported incident rates for hip fracture are incorrect. We have attempted to contact the authors regarding these concerns and have received no response. We are therefore retracting this article since the evidence presented indicates that there has been scientific misconduct. Joseph S. Alpert, MD Professor of Medicine, University of Arizona College of Medicine, Tucson, Arizona; Editor in Chief, The American Journal of Medicine

Accidental Falls↗

RETRACTED: Vitamin K deficiency and osteopenia in elderly women with Alzheimer's disease.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editors. Numerous concerns have been raised and verified regarding this paper, including authorship, lack of credible IRB review, and implausible or impossible data.

Aged↗

Homocysteine as a predictive factor for hip fracture in stroke patients.

Risk of hip fractures in stroke patients is higher than that in a reference population. Hyperhomocysteinemia is regarded as a risk factor for ischemic stroke. The high prevalence of osteoporosis among patients with homocystinuria suggests that hyperhomocysteine may also increase the risk of fractures. To determine the association between homocysteine concentration and the risk of hip fractures, we studied a cohort of stroke patients with hemiplegia. Age-adjusted incidence rates of a hip fracture were calculated for quartiles of homocysteine concentrations. Cox proportional-hazard regression was used to calculate hazard ratios for quartiles of homocysteine levels. The initial enrolment of 433 hemiplegic patients with ischemic stroke, older than 65 years old, were followed for up to 10 years. The mean plasma homocysteine concentration at the enrolment was 14.1 +/- 5.2 micromol/L. There were 33 hip fractures among men and 46 among women during the mean follow-up period of 9.0 years. The age-adjusted incidence rates per 1000 person-years for hip fractures increased almost linearly from 2.89 in the lowest to 27.87 in the highest quartiles of homocysteine levels. We conclude that hyperhomocysteinemia is one of the risk factors for hip fractures in stroke patients.

Absorptiometry, Photon↗

Negative myoglobin staining in hemiplegic muscle of acute stroke patients predicts functional recovery.

OBJECTIVE: There is little information on skeletal muscle changes in patients with acute stroke, despite the repeated observation that levels of serum creatine kinase (CK) and myoglobin (Mb) increase in the initial phase of strokes. It is also not clearly known whether the CK and Mb are derived from skeletal muscle or myocardium. DESIGN: Biceps muscle biopsies of the hemiplegic side were obtained from 157 ischemic stroke patients on the second day of stroke onset and were examined for immunoreactivity to Mb, and measurements of Mb, total CK, troponin T, epinephrine, and norepinephrine were made on the same day. The degree of disability of patients was assessed at 7 days and at 12 mos after stroke using the Barthel index and the Scandinavian Stroke Scale. The control group consisted of 159 healthy volunteers matched in age and sex. RESULTS: Lack of Mb immunoreactivity was observed in 109 patients. The prevalence of negatively stained muscle fibers ranged from 0.0% to 22.0%, with a mean of 5.9% +/- 6.0%. The mean values of serum Mb, CK, troponin T, and norepinephrine were higher in patients than those in the control group (P < 0.0001 for all indices; percentage differences were 658% for Mb, 529% for CK, and 258% for norepinephrine). A positive correlation was observed between the prevalence of negative Mb immunostaining in fibers and the Mb (r2 = 0.968, P < 0.0001), CK (r 2= 0.910, P < 0.0001), and norepinephrine levels (r2 = 0.835, P < 0.0001). During the 12-mo study period, Barthel index and Scandinavian Stroke Scale values improved. The percentage change of the Barthel index and Scandinavian Stroke Scale correlated positively with the prevalence of negative Mb immunostaining in fibers. CONCLUSIONS: It was speculated that ischemia, resulting from vasoconstriction induced by an increase in norepinephrine, may be responsible for the occurrence of fibers with negative immunoreactivity for Mb. Patients with higher negative immunostaining for Mb fibers had poor functional recovery of hemiplegia 12 mos after stroke onset. This implies that these muscular alterations may hamper functional recovery.

Age Factors↗

Effect of treadmill exercise on bone mass in female rats.

Increasing peak bone mass at skeletal maturity, minimizing bone loss during middle age and after menopause, and increasing bone mass and preventing falls in advanced age are important measures for preventing osteoporotic fractures in women. Exercise has generally been considered to have a positive influence on bone health. This paper reviews the effects of treadmill exercise on bone in young, adult, ovariectomized, and osteopenic female rats. Treadmill exercise increases cortical and cancellous bone mass of the tibia as a result of increased bone formation and decreased bone resorption in young and adult rats. The increase in lumbar bone mass seems to be more significant when long-term exercise is applied. Treadmill exercise prevents cancellous bone loss at the tibia as a result of suppressed bone resorption in ovariectomized rats, and increases bone mass of the tibia and mechanical strength of the femur, as a result of suppressed bone resorption and increased bone formation in osteopenic rats after ovariectomy. Treadmill exercise transiently decreases the serum calcium level as a result of accumulation of calcium in bone, resulting in an increase in serum 1,25-dihydroxyvitamin D(3) level and a decrease in serum parathyroid hormone level. We conclude that treadmill exercise may be useful to increase bone mass in young and adult rats, prevent bone loss in ovariectomized rats, and increase bone mass and bone strength in osteopenic rats, especially in the long bones at weight-bearing sites. Treadmill exercise may have a positive effect on the skeleton in young, and adult, ovariectomized, and osteopenic female rats.

Animals↗

Interventions to prevent bone loss in astronauts during space flight.

This paper reviews the interventions to stabilize calcium balance and bone metabolism and prevent bone loss in astronauts during space flight. Weightlessness during space flight results in calcium, vitamin D, and vitamin K deficiency, increases urinary calcium excretion, decreases intestinal calcium absorption, and increases serum calcium level, with decreased levels of serum parathyroid hormone and calcitriol. Bone resorption is increased, whereas bone formation is decreased. The loss of bone mineral density (BMD) in the spine, femoral neck and trochanter, and pelvis is 1.0-1.6% per month. High calcium intake and vitamin D supplementation during space flight does not affect bone metabolism, but prevents an elevation of serum calcium level through increased calcitriol level, while vitamin K counteracts the reduction in bone formation. However, there are no data to show the efficacy of pharmaceutical agents for prevention of development of osteoporosis in astronauts during flight, although the preventative effect of bisphosphonates, testosterone, and vitamin K2 on cancellous bone loss in the tibia or BMD loss in the hindlimb was reported in tail-suspended mature rats. It still remains uncertain whether these agents can prevent cortical bone loss caused by weightlessness in tail-suspended rats. Therefore, in addition to calcium, vitamin D, and vitamin K supplementation, agents that have both potent anti-resorptive and anabolic effects on cancellous and cortical bone may be needed to stabilize calcium balance and bone metabolism and prevent bone loss in astronauts during space flight.

Aerospace Medicine↗

Comparative effects of vitamin K and vitamin D supplementation on calcium balance in young rats fed normal or low calcium diets.

We examined the effect of vitamin K and vitamin D supplementation on calcium balance in young rats fed a normal or low calcium diet. Eighty female Sprague-Dawley rats, 6 wk of age, were randomized by the stratified weight method into eight groups with 10 rats in each group: 0.5% (normal) or 0.1% (low) calcium diet, 0.5% or 0.1% calcium diet+vitamin K (vitamin K2, menatetrenone, 30 mg/100 g, food intake), 0.5% or 0.1% calcium diet+vitamin D (25 microg/100 g, food intake), and 0.5% or 0.1% calcium diet+vitamin K+vitamin D. The duration of the study was 10 wk. Vitamin K supplementation promoted the reduction in urinary calcium excretion and retarded the abnormal elevation of serum PTH level in rats fed a low calcium diet, and stimulated intestinal calcium absorption in rats fed a normal calcium diet. Vitamin D supplementation stimulated intestinal calcium absorption with prevention of the abnormal elevation of serum PTH levels and prevented hypocalcemia in rats fed a low calcium diet, and stimulated intestinal calcium absorption in rats fed a normal calcium diet. The stimulation of intestinal calcium absorption was associated with increased serum 1,25-dihydroxyvitamin D levels. An additive effect of vitamin K and vitamin D on intestinal calcium absorption was found only in rats fed a normal calcium diet. This study shows the differential effects of vitamin K and vitamin D supplementation on calcium balance in young rats fed a normal or low calcium diet.

Animals↗