Akimitsu Miyauchi

Association of a Polymorphism of the Transforming Growth Factor-β1 Gene with Genetic Susceptibility to Osteoporosis in Postmenopausal Japanese Women

Transforming growth factor‐β (TGF‐β) is both abundant in bone and an important regulator of bone metabolism. A T→C transition at nucleotide 29 in the signal sequence region of the TGF‐β1 gene results in a Leu→Pro substitution at amino acid position 10. The possible association of this polymorphism with bone mass and the prevalence of osteoporosis has now been investigated in a total of 287 postmenopausal women from two regions (Obu City, Aichi Prefecture, and Sanda City, Hyogo Prefecture) of Japan. A significant association of TGF‐β1 genotype with bone mass was detected in both populations; bone mineral density (BMD) at the lumbar spine was greater in individuals with the CC genotype than in those with the TT or TC genotype. The frequency of vertebral fractures was significantly lower in individuals with the CC genotype than in those with the TC or TT genotypes. For each region, multivariable logistic regression analysis revealed that the frequency of the T allele was significantly higher in subjects with osteoporosis than in controls. Also, the serum concentration of TGF‐β1 in individuals with the CC genotype was significantly higher than that in age‐matched subjects with the TC or TT genotype in osteoporotic or osteopenic as well as healthy control groups. These results suggest that the T/C polymorphism of the TGF‐β1 gene is one of the genetic determinants of bone mass and that the T allele is an independent risk factor for the genetic susceptibility to osteoporosis in postmenopausal Japanese women. Thus, analysis of the TGF‐β1 genotype may be useful in the prevention and management of osteoporosis.

Distinct Anabolic Response of Osteoblast to Low‐Intensity Pulsed Ultrasound

Low‐intensity pulsed ultrasound, a form of mechanical energy transmitted as high‐frequency acoustical pressure waves, provides noninvasive therapeutic treatment for accelerating fracture repair and distraction osteogenesis. Relatively young osteoblasts respond to ultrasound by transiently upregulating message levels of immediate‐early genes as well as that of osteocalcin and insulin‐like growth factor I (IGF‐I). Osteocytes derived from newborn rat tibia and calvaria responded to a lesser extent only in c‐fos and cyclooxygenase‐2 (COX‐2) messages. Compared with the stretched osteocytes, which use stretch‐activated and parathyroid hormone (PTH)‐potentiated Ca2+ influx as an entry route to the protein kinase A (PKA) signal transduction pathways, there was no evidence of Ca2+ internalization by any of the cells tested on exposure to the ultrasound. On the other hand, inhibitors of p38 mitogen‐activated protein kinase (MAPK) and upstream phosphoinositide 3‐kinase (PI3K) blocked COX‐2 and osteocalcin upregulation by the ultrasound‐exposed ST2, murine bone marrow‐derived cells. This is distinct from the aforementioned osteocytic response to low‐frequency stretching and implies the involvement of integrins. Our findings suggested that accelerated fracture repair and distraction osteogenesis by the low‐intensity pulsed ultrasound depend, at least in part, on the stimulation of osteoblastic cells at relatively early stages of osteogenic lineage. Bone is under control of multiple regulatory mechanisms so that diverse physical forces can be reflected to the microenvironment of each cell, in turn, to the entire bone.

Association of the C–509→T polymorphism, alone or in combination with the T869→C polymorphism, of the transforming growth factor-β1 gene with bone mineral density and genetic susceptibility to osteoporosis in Japanese women

Transforming growth factor-β1 is an important local regulator of bone metabolism, acting downstream of estrogen and cooperatively with vitamin D. The possible association of a C–509→T polymorphism in the promoter region of the transforming growth factor-β1 gene, alone or in combination with a T869→C (Leu10→Pro) polymorphism, with bone mineral density and genetic susceptibility to osteoporosis was investigated in 625 postmenopausal Japanese women. The frequencies of the CC, CT, and TT genotypes of the C–509→T polymorphism in the study population were 24%, 49%, and 27%, respectively. A significant association of C–509→T genotype with bone mineral density was detected: lumbar spine (L2–L4) and total body bone mineral density values were 7% and 5% lower, respectively, in individuals with the TT genotype than in those with the CT or CC genotype. The serum concentration of transforming growth factor-β1 did not vary with C–509→T genotype. Multivariable logistic regression analysis, with adjustment for age, height, body weight, time since menopause, smoking status, body fat mass, and lean mass, revealed a significantly higher frequency of the TT genotype of the C–509→T polymorphism in 286 individuals with osteoporosis than in 170 normal controls. Analysis of combined C–509→T and T869→C genotypes showed that L2–L4 bone mineral density decreases and the prevalence of osteoporosis increases with the number of T alleles. These results suggest that the C–509→T polymorphism, alone or in combination with the T869→C polymorphism, of the transforming growth factor-β1 gene is a genetic determinant of bone mass, and that the number of T alleles in the combined genotype is a risk factor for the genetic susceptibility to osteoporosis in postmenopausal Japanese women.

Association of transforming growth factor-β1 genotype with spinal osteophytosis in Japanese women

OBJECTIVEnTo examine the possible relationship between a T-->C polymorphism at nucleotide position 29 of the transforming growth factor beta1 (TGFbeta1) gene and genetic susceptibility to radiographic spinal osteophytosis.nnnMETHODSnA total of 540 postmenopausal Japanese women were subjected to radiography of the spine and determination of bone mineral density (BMD) for the lumbar spine and total body. Changes in lumbar intervertebral discs were examined in 67 individuals with either osteoporosis or spinal osteophytosis by magnetic resonance imaging (MRI). TGFbeta1 genotype was determined with an allele-specific polymerase chain reaction assay. The serum concentration of TGFbeta1 was measured in 29 control subjects and in 36 patients with spinal osteophytosis.nnnRESULTSnAmong all study subjects, the prevalence of radiographic spinal osteophytosis in individuals with the CC genotype was greater than that in those with the TC or TT genotype. Logistic regression analysis, adjusted for age, height, body weight, time since menopause, smoking status, body fat, lean mass, and either lumbar spine or total body BMD, demonstrated that the frequency of the C allele in subjects with spinal osteophytosis was significantly greater than that in those without this condition. Comparison among control, osteoporosis, and spinal osteophytosis groups also revealed that the C allele was more prevalent in subjects with osteophytosis than in controls, even after adjustment for BMD. In contrast, as previously shown, the frequency of the C allele was lower in osteoporosis patients than in controls. The intervertebral disc area and the ratio of disc area to vertebral body area, as determined by MRI, were also lowest in subjects with the CC genotype. The serum concentration of TGFbeta1 increased with the number of C alleles in both controls and patients with spinal osteophytosis.nnnCONCLUSIONnThe T29-->C polymorphism of the TGFbeta1 gene exhibited inverse patterns of association with genetic susceptibility to spinal osteophytosis and with osteoporosis. Although radiographic evaluation of osteophytes might not reflect the actual disease severity, the C allele, which protects against osteoporosis, may be a risk factor for genetic susceptibility to spinal osteophytosis.

Effect of age on body sway assessed by computerized posturography

The swaying and postural instability frequently seen in elderly subjects had not been analyzed quantitatively in detail until the introduction of computerized posturography. In order to assess the changes of body sway with aging, we performed computerized posturography in 144 subjects (51 men and 93 women, between the ages of 22 and 88 years) without specific neurological or metabolic disorders. The total and timed track length of the center of gravity, reflecting the distance of sway, increased with advancing age, with a highly significant positive correlation, without marked sex differences. The total area covered by the track of the center of gravity (expressing the extent of sway) also showed a similar tendency. Track density per unit area, expressing the efficiency of postural control, in contrast, decreased with age, showing a significant negative correlation with age, but only when the subjects had their eyes open; this decrease did not occur when they had their eyes closed. The Romberg ratio, an index of exacerbation of sway on eye closure, showed little change with a tendency for slight alleviation of sway and improvement in the efficiency of its control. Computerized posturography appears to be a useful tool with which to analyze the mechanism of swaying associated with old age.

Association of transforming growth factor β1 genotype with therapeutic response to active vitamin D for postmenopausal osteoporosis.

Transforming growth factor β (TGF‐β) is an important regulator of bone metabolism, its effects being intertwined with those of estrogen and vitamin D. A T→C polymorphism in exon 1 of the TGF‐β1 gene, which results in the substitution of proline for leucine, is associated with bone mineral density (BMD). However, it is not known whether this polymorphism affects the response to treatment with active vitamin D or to hormone replacement therapy (HRT) in individuals with osteoporosis. Changes in BMD at the lumbar spine (L2–L4 BMD) were compared among TGF‐β1 genotypes in 363 postmenopausal Japanese women who were divided into three groups: an untreated, control group (n = 130), an active vitamin D treatment group (n = 117), and an HRT group (n = 116). TGF‐β1 genotype was determined with an allele‐specific polymerase chain reaction assay. In the control group, the rate of bone loss decreased according to the rank order of genotypes TT (homozygous for the T allele) > TC (heterozygous) > CC (homozygous for the C allele), with a significant difference detected between the CC and TT genotypes. The positive response of L2–L4 BMD to HRT increased according to the rank order of genotypes TT < TC < CC, although the differences among genotypes were not statistically significant. Individuals with the CC genotype responded to active vitamin D treatment with an annual increase in L2–L4 BMD of 1.6%, whereas those with the TT or TC genotypes similarly treated lost bone to a similar extent as did untreated subjects of the corresponding genotype. These results suggest that TGF‐β1 genotype is associated with both the rate of bone loss and the response to active vitamin D treatment.

αvβ3 Integrin ligands enhance volume-sensitive calcium influx in mechanically stretched osteocytes

We propose that specific osteocyte–matrix interactions regulate the volume-sensitive calcium influx pathway, which we have shown is mediated by stretch-activated cation channels (SA-Cat) and is essential for the stretch-activated anabolic response in bone. The current study measured the hypotonic swelling-induced increase in cytosolic calcium concentration, [Ca2+]i, in rat osteocytes, and found that cells adherent to different matrices behave differently. Osteopontin and vitronectin, matrix molecules that bind the αVβ3 integrin, induced larger responses to the hypotonic swelling than other matrix molecules that bind other integrins. Addition of echistatin, which is a soluble αVβ3 ligand, significantly enhanced the hypotonic [Ca2+]i increase in addition to inducing an immediate increase in [Ca2+]i by itself. These results strongly support the contention that αVβ3 integrin signaling in osteocytes interacts with that in mechanotransduction, which is downstream of SA-Cat.

Prostate Cancer-Induced Oncogenic Hypophosphatemic Osteomalacia

A 65-year-old male with prostate carcinoma showed mild hypocalcemia of 7.9 mg/dl, marked hypophosphatemia of 1.7 mg/dl, hyperphosphaturia (tubular reabsorption of phosphorus 43% and tubular threshold for phosphorus of 0.6 mg/dl), low serum 1,25 (OH)2D level of less than 5 pg/ml and osteomalacia indicated by a marked increase of relative osteoid volume and fractional formation rate in the undecalcified section. Oncogenic osteomalacia due to prostatic carcinoma with suppression of 1,25 (OH)2D production and phosphaturia was suggested.

Comparison of the analgesic effects of bisphosphonates : etidronate, alendronate and risedronate by electroalgometry utilizing the fall of skin impedance

Analgesic effects of etidronate, alendronate and risedronate were compared in patients with osteoporosis and/or osteoarthritis by measuring the fall of skin impedance along with conventional subjective pain-estimation by visual rating scale (VRS). One hundred ninety-nine postmenopausal women consulting the Osteoporosis and Osteoarthritis Clinic of Katsuragi Hospital complaining of back and/or knee pain were randomly divided into four groups; Group A (49 subjects) given 5xa0mg/day alendronate, Group E (50 subjects) 200xa0mg/day etidronate, Group R (50 subjects) 2.5xa0mg/day risedronate and Group P no bisphosphonate. None of the four groups showed significant deviation from others as to age and parameters of bone metabolism. Proportions of subjects with osteoporosis was 18–40%. Those with osteoarthritis of the spine and knee, higher than Grade II according to the Nathan and Lawrence-Kellgren scale, respectively, was 45 and 61%, respectively, without a significant difference among the four groups. Significant positive correlation was found between the fall of skin impedance and pain expressed in VRS. Attenuation of exercise-induced fall of skin impedance and also subjective pain expressed in VRS was greatest in Group E with a highly significant difference from Groups A (Pxa0=xa00.0002 and Pxa0<xa00.0001), R (Pxa0<xa00.0001 and Pxa0=xa00.0014) and P (Pxa0<xa00.0001 and Pxa0<xa00.0001). Neither A nor R showed significant difference from P as to the fall of skin impedance. Among the three bisphosphonates tested, etidronate appeared to be outstanding in analgesic effects.

Analgesic effect of etidronate on degenerative joint disease

Abstract In the present study, 80 patients with degenerative joint disease, spondylosis deformans, and/or osteoarthritis of the knee with back or joint pain, especially on movement and strain, were randomly divided into four groups. Group A received no etidronate, while groups B, C and D received 66, 133 and 200 mg/day etidronate, respectively, for 12 months. Every 3 months, after evaluating subjective pain on a visual rating scale (VRS), skin impedance was measured with subjects in a quiet sitting position and with the application of various strains on the spine and knee, including standing up from quiet sitting on a chair, bending forward to flex the spine, squatting to flex the knee, walking 20 paces on a flat floor, ascending 10 stair steps and descending 10 stair steps. A dose-related improvement of subjective pain on the VRS with a parallel decrease in the percentage fall in skin impedance was noted. The intra-individual coefficients of variation (CV) of L1–L4 bone mineral density (BMD) on dual-energy X-ray absorptiometry were calculated as a possible index for spondylotic changes before and after treatment as an indication of spondylotic deformity, because no established method is yet available to evaluate such changes objectively. A dose-related decrease in CV of BMD was also noted, parallel to the analgesic effect.