Effects of short-term fasting on the Akt-mediated pathway involved in protein metabolism in chicken skeletal muscle

In the present study, we show that short-term (4 h) fasting significantly decreased the levels of protein synthesis-related factors such as the plasma insulin concentration, skeletal muscle pAkt, and pS6 levels in 2-wk-old chickens (P < 0.05). An intravenous injection of insulin significantly elevated the contents of pAkt and p-S6 in the skeletal muscle (P < 0.01). These findings suggest that decreasing the plasma insulin causes the downregulation of the Akt/S6 pathway in chicken skeletal muscle under short-term fasting conditions. However, protein synthesis was not significantly affected by short-term fasting. In addition, no significant change was observed in the levels of proteolysis-related factors such as plasma N^τ-methylhistidine, phosphorylated forkhead box class O, and muscle ring finger-1 during 4-h fasting, indicating that short-term fasting does not induce skeletal muscle proteolysis in chickens. Interestingly, atrogin-1 expression significantly increased after 2-h fasting (P < 0.05), and insulin injection significantly reversed the fasting-induced atrogin-1 expression in chicken skeletal muscle (P < 0.01). Collectively, these findings suggest that short-term fasting downregulates the insulin-stimulated Akt/S6 pathway but does not significantly affect protein synthesis and proteolysis in chicken skeletal muscle, and that atrogin-1 expression is upregulated in a FOXO1-independent manners.

Detection of rotavirus in clinical specimens using an immunosensor prototype based on the photon burst counting technique

In this study, a sensitive fluorescence sensor was developed for the detection of small, fluorescence-labeled particles dispersed in a solution. The prototype system comprises of a laser confocal optical system and a mechanical sample stage to detect photon bursting of fluorescence-labeled small particles in sample volumes less than 5 μL within 3 minutes. To examine the feasibility of the prototype system as a diagnostic tool, assemblages of rotavirus and fluorescence-labeled antibody were analyzed. The detection sensitivity for rotavirus was 1 × 10⁴ pfu/mL. Rotavirus in stool samples from patients with acute gastroenteritis was also detected. The advantages and disadvantages of this immunosensor with respect to ELISA and RT-PCR, the current gold standards for virus detection, are discussed.

IL-28B (IFN-λ3) and IFN-α synergistically inhibit HCV replication

Genetic variation in the IL-28B (interleukin-28B; interferon lambda 3) region has been associated with sustained virological response (SVR) rates in patients with chronic hepatitis C treated with peginterferon-α and ribavirin. However, the mechanisms by which polymorphisms in the IL-28B gene region affect host antiviral responses are not well understood. Using the HCV 1b and 2a replicon system, we compared the effects of IFN-λs and IFN-α on HCV RNA replication. The anti-HCV effect of IFN-λ3 and IFN-α in combination was also assessed. Changes in gene expression induced by IFN-λ3 and IFN-α were compared using cDNA microarray analysis. IFN-λs at concentrations of 1 ng/mL or more exhibited concentration- and time-dependent HCV inhibition. In combination, IFN-λ3 and IFN-α had a synergistic anti-HCV effect; however, no synergistic enhancement was observed for interferon-stimulated response element (ISRE) activity or upregulation of interferon-stimulated genes (ISGs). With respect to the time course of ISG upregulation, the peak of IFN-λ3-induced gene expression occurred later and lasted longer than that induced by IFN-α. In addition, although the genes upregulated by IFN-α and IFN-λ3 were similar to microarray analysis, interferon-stimulated gene expression appeared early and was prolonged by combined administration of these two IFNs. In conclusion, IFN-α and IFN-λ3 in combination showed synergistic anti-HCV activity in vitro. Differences in time-dependent upregulation of these genes might contribute to the synergistic antiviral activity.

Associations of vertebral deformities and osteoarthritis with back pain among Japanese women: the Hizen-Oshima study

We examined the spinal distribution of the types of vertebral deformities and the associations of vertebral deformities and osteoarthritis with back pain in Japanese women. Midthoracic and upper lumbar vertebrae were more susceptible to deformity. Vertebral deformity and osteoarthritis were frequent and were associated with back pain.

INTRODUCTION

Vertebral fractures due to osteoporosis and osteoarthritis are both common and significant health problems in aged people. However, little is known about the descriptive epidemiology of the individual deformity types and the relative clinical impact in women in Japan.

METHODS

Lateral radiographs were obtained from 584 Japanese women ages 40 to 89 years old. Deformities were defined as vertebral heights of more than 3 standard deviations (SDs) below the normal mean. Osteoarthritis was defined as Kellgren-Lawrence (KL) grade 2 or higher. Information on upper or low back pain during the previous month was collected by questionnaire. We compared the spinal distribution of the three types of vertebral deformities (wedge, endplate, and crush) typical of fractures and examined the associations of number and type of vertebral deformities and osteoarthritis with back pain.

RESULTS

Fifteen percent of women had at least one vertebral deformity and 74% had vertebral osteoarthritis. The prevalence of upper or low back pain was 30.1%. Deformities were most common in the midthoracic and upper lumbar regions and wedge was the frequent type, followed by endplate and crush. Multiple logistic regression analysis showed that the odds of back pain was 3.0 (95% CI 1.5-6.3) times higher for women with a single wedge deformity and 3.2 (95% CI 1.0--0.6) times higher for women with two or more wedge deformities, compared to women with no wedge deformity. Vertebral osteoarthritis was associated with back pain (OR 1.8, 95% CI 1.1-2.9), independent of other covariates including age and deformities.

CONCLUSION

Our results in this group of Japanese women are similar to and consistent with results reported previously in other populations of Japanese and Caucasians.

Beneficial effect of risedronate for preventing recurrent hip fracture in the elderly Japanese women

SUMMARY

A 36-month observational study compared the incidence of unaffected side hip fracture in Japanese female osteoporosis patients with a history of hip fracture between 173 patients receiving risedronate and 356 risedronate-untreated controls. New hip fractures were significantly less frequent in the risedronate group, suggesting a preventive effect in high-risk patients.

INTRODUCTION

The purpose of this study was to investigate the preventive effect of risedronate on second hip fracture immediately following a first hip fracture in Japanese female osteoporosis patients with unilateral hip fracture.

METHODS

We conducted a prospective matched cohort study in 184 patients treated with risedronate and 445 patients not receiving risedronate after discharge from hospital. Both groups were followed-up for 36 months, and the incidence of unaffected side hip fracture and the frequency of adverse events were assessed.

RESULTS

Efficacy could be investigated in 173 patients from the risedronate group and 356 patients from the control group. Hip fracture was detected in 5 and 32 patients, respectively. Kaplan-Meier estimates of the 36-month fracture incidence were 4.3% in the risedronate group and 13.1% in the control group (P = 0.010, log-rank test). The hazard ratios (95% confidence intervals) obtained by univariate and multivariate analysis were 0.310 (0.121-0.796) and 0.218 (0.074-0.639), respectively, indicating a significantly lower incidence of unaffected side hip fracture in the risedronate group. Adverse events occurred in 38 patients (48 events) from the risedronate group and 94 patients (108 events) from the control group, with serious adverse events in 21 patients (26 events) and 78 patients (88 events), respectively.

CONCLUSIONS

No significant differences were observed between the two groups. The incidence of unaffected side hip fracture was significantly lower in the risedronate group. Accordingly, risedronate may have a preventive effect on hip fracture in high-risk Japanese female osteoporosis patients for fracture with a history of unilateral hip fracture.

Osteoporotic changes of subchondral trabecular bone in osteoarthritis of the knee: a 3-T MRI study

SUMMARY

Subchondral trabecular bone structure was analyzed in knee osteoarthritis (OA) patients using 3-T MRI to investigate structural features of subchondral trabecular bone of knee OA. With OA progression, osteoporotic changes were observed in the lateral joint, showing a higher correlation than sclerotic changes in the medial joint.

INTRODUCTION

To investigate structural features of subchondral trabecular bone of knee osteoarthritis (OA).

METHODS

Sixty knees with KL grade 0-4 (all female) were examined. Fast imaging employing steady-state acquisition-cycled phases (FIESTA-c) and FatSat Spoiled gradient recalled acquisition in the steady state (SPGR) images were acquired by 3-T MRI. At four sites (the medial femur, medial tibia, lateral femur, and lateral tibia), subchondral trabecular bone structure was analyzed by FIESTA-c imaging, cartilage area was measured by SPGR imaging, and their correlation was analyzed. In addition, the subjects were classified into four groups from the cartilage area measured by SPGR imaging, and subchondral trabecular bone structure in each group was compared.

RESULTS

As cartilage area decreased in the medial joint, bone volume fraction and trabecular thickness in the medial tibia increased, and bone volume fraction, trabecular thickness, number, and connectivity in the lateral femur and lateral tibia decreased (r ≥ 0.4 or ≤-0.4, p ≤ 0.001). Compared to medially, the changes laterally showed a higher correlation. When the medial-lateral ratio of trabecular thickness in the tibia was determined, it had the highest correlation coefficient (r=-0.7, p < 0.001). These changes were not significantly detected in the early stage.

CONCLUSIONS

To more sensitively detect OA changes in subchondral trabecular bone structure, a focus on osteoporotic changes in the lateral joint and the medial-lateral ratio would be useful. Detectability of early OA remains unknown, but based on a strong correlation with the degree of OA progression, trabecular structural analysis of subchondral bone may be a useful parameter to evaluate OA severity and evaluate treatment.

Adhesion of tissue sections from eleven organs on glass slides with amino group coatings

The adhesion of immunohistochemically stained tissue sections from eleven different organs on microscope slides was compared. Skin, trachea and mammary gland tissue sections heat-treated for antigen retrieval exhibited strong adhesive retention on glass slides coated with self-assembled monolayers containing amino groups at high density.

Effect of amino group density for prevention of mammary gland tissue detachment from coated glass surface

Tissue detachment from histological glass slides coated with different amino group densities was investigated during heat treatment for immunohistochemical staining. In both sow and piglet mammary gland tissues, the results clearly showed strong adhesion and high retention on self-assembled monolayers with high amino group density.

In vivo structural analysis of subchondral trabecular bone in osteoarthritis of the hip using multi-detector row CT

OBJECTIVE

With developments in clinical computed tomography (CT), in vivo analysis of patients' bone microstructure has become increasingly possible. We analyzed the subchondral trabecular bone of hip osteoarthritis (OA) patients using multi-detector row CT (MDCT) to closely examine the structural changes that occur as OA progresses.

DESIGN

47 female hip joints were studied: 20 with OA secondary to hip dysplasia (11 advanced OA, nine early-moderate OA), seven with hip dysplasia without OA, and 20 normal. The images' maximal spatial resolution was 280 × 280 × 500 μm. Regions of interest (ROIs) were the subchondral trabecular bones of the acetabulum and femoral head. Measurement parameters were bone volume fraction (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular separation (Tb.Sp), structure model index (SMI), trabecular bone pattern factor (TBPf), Euler's number, and degree of anisotropy (DA). Relationships between joint space volume and these parameters were analyzed.

RESULTS

With decreasing joint space, Tb.Th and BV/TV increased, and Tb.Sp, Tb.N, SMI, TBPf, and DA decreased significantly. The microstructures were significantly different between the early to advanced OA groups and the normal and dysplasia groups; there was no significant difference between the normal and dysplasia groups.

CONCLUSIONS

Changes of subchondral trabecular bone structure in OA could be evaluated using MDCT, despite imperfect spatial resolution and limited accuracy. Trabecular bone thickening and associated structural changes may be closely related to OA. Changes were observed in early to advanced OA, but not in dysplasia. This method may help to further elucidate OA pathogenesis, determine the therapeutic strategy, and evaluate therapy.

Bone mineral densities in patients with developmental dysplasia of the hip

Bone mineral density (BMD) of the lumbar spine, ultradistal radius, and calcaneus were significantly higher in the developmental dysplasia of the hip (DDH) patients than in the controls. Therefore, our data suggest that BMDs at different skeletal sites are greater in patients with DDH than in healthy women.

INTRODUCTION

DDH has been acknowledged as a potentially preosteoarthritic condition that results in the development of hip osteoarthritis. Patients with DDH have been reported to have abnormal morphology of the pelvis and spine. Additional research, including that of bone quality, needs to be conducted to elucidate the pathogenetic mechanism of this disease. We therefore sought to determine whether BMD differs between healthy women and women with DDH.

METHODS

We measured BMD in 40 women who were scheduled to undergo pelvic osteotomy for DDH (average age, 45.3 years) and in 31 healthy women used as age-matched controls (average age, 47.5 years). BMDs of the lumbar spine, radius, and calcaneus were measured.

RESULTS

BMDs of the lumbar spine, ultradistal radius, and calcaneus were significantly higher in the DDH patients than in the controls.

CONCLUSIONS

Therefore, our data suggest that BMDs at different skeletal sites are greater in patients with DDH than in healthy women.

Potentiation of glucocorticoid receptor (GR)-mediated signaling by the immunosuppressant tacrolimus in rheumatoid synoviocytes

OBJECTIVE

The immunosuppressant tacrolimus is known to enhance many aspects of glucocorticoid. In this study, we investigated the effects of tacrolimus on glucocorticoid receptor (GR) signaling using rheumatoid fibroblast-like synoviocytes (RA-FLS).

METHODS

The nuclear translocation of GR was analyzed by immunocytochemistry. The DNA binding activity of p65 was assayed by a functional ELISA kit using nuclear extracts. GR-associated FK506-binding protein-51 (FKBP-51) was analyzed by Western blotting following immunoprecipitation of glucocorticoid receptor (GR) complexes.

RESULTS

High concentrations (10-7M) of Dexamethasone (Dex) induced GR translocation to the nucleus in RA-FLS. However, the nuclear GR translocation did not occur with low concentrations of Dex (10-9M). Tacrolimus treatment of RA-FLS results in potentiation of GR translocation to the nucleus even in the presence of a low concentration of Dex (10-9M). GR-associated FKBP-51 decreased after tacrolimus treatment. Furthermore, tacrolimus also decreased the IL-1Beta-induced DNA binding activity of p65, a subunit of NF-KappaB, in the presence of 10-9 M of Dex.

CONCLUSION

These data suggest that tacrolimus exerts anti-inflammatory properties by potentiating the GR signaling through the GR-immunosuppressant-binding proteins (immunophilins) interaction and its nuclear transport in rheumatoid synovium.

Sweat antigen induces histamine release from basophils of patients with cholinergic urticaria associated with atopic diathesis

BACKGROUND

We previously demonstrated that the semipurified human sweat antigen causes skin reactions and histamine release from basophils via specific IgE in patients with atopic dermatitis (AD). Patients with cholinergic urticaria (ChU) also develop skin reactions and histamine release of basophils in response to autologous sweat.

OBJECTIVES

To study whether or not patients with ChU share sensitivity for the sweat antigen with patients with AD and to study the clinical characteristics among patients with ChU and the relationship with histamine-release activity of basophils.

METHODS

The sweat antigen that induces histamine release from basophils of patients with AD was prepared by Con-A, anion-exchange and reverse-phase chromatography. Relationships between histamine-release activity against the sweat antigen and clinical features of patients with ChU were analysed.

RESULTS

Twenty-three of 35 patients with ChU showed > 5% net histamine release in response to the semipurified sweat antigen, whereas none of healthy controls did so. In patients with ChU, histamine release in response to semipurified sweat antigen significantly correlated with the level of serum IgE and eosinophil numbers in peripheral blood. Incidence of each atopic disease in patients with ChU tended to be higher than in the general Japanese population. When the patients were categorized according to their responses in the histamine release test, the positive group tended to show a higher incidence of AD and bronchial asthma compared with the negative group.

CONCLUSIONS

ChU and AD may share hypersensitivity to common antigens in sweat. The sweat allergy and atopic diathesis are associated with each other.

Rotational acetabular osteotomy for advanced osteoarthritis secondary to developmental dysplasia of the hip

We evaluated the results of rotational acetabular osteotomy in 44 hips (42 patients) with advanced osteoarthritis secondary to developmental dysplasia. The mean age of the patients at surgery was 43.4 years (30 to 59) and the mean follow-up was 12.1 years (8 to 19). The mean Merle d'Aubigné clinical score improved from 10.8 points (8 to 15) pre-operatively to 13.5 points (6 to 18) at follow-up. Radiologically, this procedure produced adequate improvement regarding cover of the femoral head. At follow-up, the osteoarthritic stage assessed using the Japanese Orthopaedic Association grading, was improved in 11 hips (25%), unchanged in 22 (50%) and had progressed in 11 (25%). The mean pre-operative roundness index of the femoral head was significantly different in the 33 hips which had improved or maintained their osteoarthritic stage compared with the 11 which had progressed (53.7% vs 63.7%; p < 0.001). Osteoarthritis with a round femoral head is considered to be an indication for rotational acetabular osteotomy, even in advanced stages of the disease.

Rotational acetabular osteotomy with a resection of the lateral edge of the acetabulum for the treatment of advanced coxarthrosis

INTRODUCTION

We compared the functional and radiological results of a rotational acetabular osteotomy (RAO) with and without a resection of the lateral edge of the acetabulum. The purpose of the resection was to obtain good joint congruency.

MATERIALS AND METHODS

RAO was performed on 71 hips to treat advanced coxarthrosis caused by acetabular dysplasia. RAO without a resection (non-resection group) was performed in 54 patients (57 hips) with a median age of 43.1 years. The remaining 14 patients (14 hips), who had a median age of 44.6 years, received RAO with a resection of the lateral edge of the acetabulum (resection group).

RESULTS

The average postoperative total hip joint score was better than the average preoperative score in the non-resection group (P < 0.001), but not in the resection group. In the resection group, all hips displayed progressive osteoarthritic change and ten hips had chondrolysis of the hip joint and a collapse of the transferred acetabulum within 3 years. In the non-resection group, 15 hips showed progressive osteoarthritic change, 24 hips had no change, and 18 hips showed a decrease in the osteoarthritic stage.

CONCLUSION

Our findings demonstrated that resection of the lateral edge of the acetabulum is not a useful adjunct to the RAO procedure for the treatment of advanced coxarthrosis.

Barium aspiration showing crazy-paving appearance on high-resolution computed tomography

We encountered a case showing a crazy-paving appearance on high-resolution computed tomography (HRCT), which mimicked various pulmonary diseases, e.g. pulmonary alveolar proteinosis, or non-specific interstitial pneumonia, but which we ultimately determined to be due to barium aspiration. The initial radiological findings were considered to be most likely due to pulmonary alveolar microlithiasis, because the crazy-paving appearance had high density, resembling calcification. However, distribution was limited to the area of dependent drainage of the right lung. Since a barium swallowing study had been performed 2 weeks before the CT examination, and since the follow-up HRCT showed improvement we reached a diagnosis of barium aspiration. Although barium aspiration may yield findings similar to other diseases with crazy-paving appearance, it is possible to identify it because of the limited distribution and high density.

Pharmacokinetic study of darbepoetin alfa: absorption, distribution, and excretion after a single intravenous and subcutaneous administration to rats

KRN321 is a hyperglycosylated analogue of recombinant human erythropoietin (rHuEPO, epoetin alfa), and its absorption, distribution, and excretion have been studied after a single intravenous and subcutaneous administration of 125I-KRN321 at a dose of 0.5 microg kg-1 to male rats. The half-lives of immunoreactive radioactivity in the terminal phase after intravenous and subcutaneous administration were 14.05 and 14.36 h, respectively, and the bioavailability rate after subcutaneous administration was 47%. The total radioactivity in tissues was lower than that in the serum in all tissues excluding the thyroid gland and skin at the injection site (subcutaneous administration). The maximum concentrations were observed in the bone marrow or skin at the injection site followed by the thyroid gland, kidneys, adrenal glands, spleen, lungs, stomach and bladder. The radioactivity found in trichloroacetic acid-precipitated fractions suggested that a high-molecular weight compound, unchanged or mixed with endogenous protein, distributed to the tissues after administration. The whole-body autoradiographic findings in both groups were in agreement with the tissue distribution mentioned above. The blood cell uptake of KRN321 was low for both groups. The excretion ratios of radioactivity into urine and faeces up to 168 h were 71.4 and 14.1% after the intravenous administration and 74.9 and 12.0% after the subcutaneous administration. There was no difference in the excretion profile of radioactivity between the two groups.

Nanobacteria-Like Particles in Human Arthritic Synovial Fluids

We investigated the existence of nanosize particles in synovial fluids of rheumatoid arthritis and osteoarthritis patients. These specimens were cultured under mammalian cell culture conditions (37 degrees C; 5% CO2/95% air) for a long period. After about 2 months, many nanoparticles appeared and they gradually increased in number and in size. The nanobacteria-like particles exist in synovial fluids of arthritis patients. The possibility of their existence and pathogenesis in various diseases should be verified cautiously.

Postoperative changes in protein-induced vitamin K absence or antagonist II levels after hepatectomy in patients with hepatocellular carcinoma: relationship to prognosis

BACKGROUND

alpha-Fetoprotein (AFP) has been used as a marker for hepatocellular carcinoma (HCC). However, AFP levels are often high in patients with chronic hepatitis or cirrhosis. Protein-induced vitamin K absence or antagonist II (PIVKA-II) is more sensitive for the diagnosis of HCC and prediction of patient survival. Changes in these markers after treatment may reflect treatment curability and patient outcome.

METHODS

We conducted a retrospective analysis of prognosis of 63 HCC patients with high preoperative levels of AFP and PIVKA-II who underwent hepatectomy and examined the relationship between postoperative changes in both markers at 1 month and patient survival. Subjects were divided into three groups according to changes in these tumour markers after hepatectomy: normalization (N) group, decreased but still above the normal level (D) group and unchanged (U) group.

RESULTS

There were no significant differences in the numbers of patients who developed tumour recurrence between changes in AFP and PIVKA-II. Survival analysis showed no significant differences in tumour-free and overall survivals between groups with respect to AFP level. The PIVKA-II-N group showed significantly better tumour-free and overall survival compared with the D and U groups (p<0.01). Multivariate analysis that included other prognostic factors identified changes in PIVKA-II level as a significant and independent prognostic factor associated with overall survival.

DISCUSSION

Although changes in AFP did not correlate with patient prognosis, normalization of PIVKA-II was significantly associated with good patient survival after hepatectomy. Normalization of PIVKA-II after hepatectomy reflected the efficacy of treatment and is a suitable predictor of prognosis in HCC patients.

Establishment of a clonal human mesenchymal cell line that retains multilineage differentiation capacity from a spinal hamartoma

We isolated a single-cell-derived cell line from a spinal hamartoma, a which occurred in a newborn boy and was associated with a rudimentary limb. The maternal cells (HHC-7) differentiated into osteoblasts, chondrocytes, adipocytes, and skeletal muscles when they were cultured in differentiation-inducing media specific to each mesenchymal cell. We isolated a single-cell-derived clonal cell line (Clone K) after transfection with SV40 T antigen. These cells expressed CD73 and CD117, while being negative for expression of CD45. Clone K cells cultured in an osteogenic differentiation medium increased ALP activity and expressed mRNAs for Runx2 and osteocalcin. Treatment with rhBMP-2 induced Clone K cells to differentiate into both osteoblasts and chondrocytes. These cells expressed mRNAs for Sox9 and aggrecan in addition to osteogenic markers. Culture in an adipogenic differentiation medium induced Clone K cells to differentiation into adipocytes, which expressed mRNAs for PPARgamma2 and a2P. Clone K cells cultured in a serum-depleted medium generated desmin-positive cells and expressed MyoD1 mRNA. Clone K cells exhibited numerous alpha-smooth muscle actin-positive cells; however, treatment with rhBMP-2 decreased their number. Clone K cells, transplanted with a carrier containing rhBMP-2 into the muscles of SCID mice, generated ectopic endochondral bone formation. In these tissues, several osteoblasts and chondrocytes expressed SV40 T antigen, indicating their Clone K cell origin. Thus, Clone K cells are useful tools for analyzing the characteristics of human multipotential mesenchymal progenitors.

Doppler effect in resonant photoemission from SF6: correlation between Doppler profile and Auger emission anisotropy

Fragmentation of the SF6 molecule upon F 1s excitation has been studied by resonant photoemission. The F atomiclike Auger line exhibits the characteristic Doppler profile that depends on the direction of the photoelectron momentum relative to the polarization vector of the radiation as well as on the photon energy. The measured Doppler profiles are analyzed by the model simulation that takes account of the anisotropy of the Auger emission in the molecular frame. The Auger anisotropy extracted from the data decreases with an increase in the F-SF5 internuclear distance.

Chromatin structure of yeast minichromosomes containing triplet repeat sequences associated with human hereditary neurological diseases

Expansion of triplet repeat sequences such as (CTG)n, (CGG)n, and (GAA)n causes human genetic diseases. Since DNA is packaged into arrays of nucleosomes in eukaryotic cells, chromatin may be involved in the mechanism of triplet repeat diseases. To elucidate this issue, we have examined effects of triplet repeat sequences on the chromatin organization in vivo using well defined yeast minichromosomes. We show here that (CGG)12 disrupts an array of positioned nucleosomes, whereas (CTG)12 promotes the nucleosome formation. Thus, triplet repeat sequences can affect the chromatin organization in vivo, which may contribute to the triplet repeat expansion or alterations in the expression of genes associated with triplet repeat diseases.

A nonsurgical technique to create an esophagostomy for difficult cases of percutaneous endoscopic gastrostomy

BACKGROUND

We developed a minimally invasive technique of esophagostomy called percutaneous transesophageal gastrotubing (PTEG) using a rupture-free balloon (RFB) for enteral nutrition and drainage as well as percutaneous endoscopic gastrostomy (PEG). PTEG using RFB allows surgeons to create a nonsurgical esophagostomy even in difficult cases of PEG (i.e., total gastrectomized patients and massive ascites).

METHODS

To create the PTEG, a RFB is inserted into the esophagus through the nose and inflated. The RFB is punctured with a needle at the left neck under ultrasonographic vision. A guidewire is inserted through the needle, followed by dilatation of the punctured site using a dilator with sheath. Finally, the tube is inserted into the gastrointestinal tract and the sheath is peeled off.

RESULTS

From January 1998 to June 2002, we treated 115 patients using PTEG with a RFB and there were no major complications. Therapeutic results are as good as those for PEG and it took approximately 15 min to perform.

CONCLUSIONS

PTEG with RFB is as safe as PEG and is simple and less invasive. It can be used in some cases for which PEG is contraindicated.

Anisotropic ultrafast dissociation probed by the Doppler effect in resonant photoemission from CF4

The resonant Auger spectrum from the decay of F 1s-excited CF4 is measured. Several lines exhibit a nondispersive kinetic energy as the exciting photon energy is tuned through the resonance region. The F 1s(-1) atomiclike Auger line is split into two components due to the emission of Auger electrons by a fragment in motion, when electron emission is observed along the polarization vector of the light. This Doppler splitting is direct evidence that the core excitation leads to T(d)-->C(3v) symmetry lowering, by elongation of a specific C-F bond preferentially aligned along the polarization vector of the incident photon.

Doppler-free resonant Raman auger spectroscopy of Ne+ 2s2p(5)3p excited states

Using very high resolution achieved by the Doppler-free resonant Raman Auger technique, we have resolved the lowest terms of the series of inner-valence excitations 2s2p(5)((1,3)P)np 2S, 2P, and 2D in Ne+. The measured Auger anisotropic parameters and branching ratios help to establish the assignments of these levels. The measured lifetime widths are in reasonable agreements with ab initio calculations available in the literature.

Prevalence of vertebral deformity and its associations with physical impairment among Japanese women: The Hizen-Oshima Study

Vertebral fractures are a hallmark of postmenopausal osteoporosis and an important end point in trials of osteoporosis treatment, but the clinical significance of vertebral deformities remains uncertain. We examined the prevalence of vertebral deformity and associations of vertebral deformities and other characteristics with physical functioning among 584 Japanese women ages 40 to 89 years. Lateral spine radiographs were obtained and radiographic vertebral deformities were assessed by quantitative morphometry, defined as vertebral heights more than 3 SD below the normal mean. A self-administered questionnaire was used to survey participants about difficulty in performing selected basic and instrumental activities of daily living (ADL). Overall, 15% of women had at least one vertebral deformity, and 8% had 2 or more. The prevalence of vertebral deformities increased progressively with age. Half of women ages 80 and over had vertebral deformities. Impaired function was defined as difficulty performing 3 or more ADLs. After adjusting for age, the odds of impaired function were increased by 1.4 times (95% CI: 0.7, 2.9) in women with a single vertebral deformity, and 3.1 times (1.4, 6.8) in those with two or more deformities. Additional adjustment for number of painful joints, number of comorbidities, body mass index, and back pain did not materially alter these findings. In conclusion, women with multiple vertebral deformities had significantly greater impaired function. The association was independent of age, back pain and the number of painful joints, suggesting that deformities may impair function even when back pain is not present.

[Percutaneous trans-esophageal gastro-tubing (PTEG): experience of home care with a long-term PTEG]

PURPOSE

Percutaneous trans-esophageal gastro-tubing (PTEG) was developed as a new method of esophagostomy for drainage and feeding. It is especially easy to create a PTEG for patients in whom it is difficult to perform a percutaneous endoscopic gastrostomy (PEG). Here we report a satisfactory experience with a patient with dysphagia for whom we improved the patient's QOL with PTEG. The patient suffered from terrible dysphagia due to Parkinson's disease and was in the postoperative recovery status after undergoing a gastrectomy for gastric cancer. PTEG allowed the patient to receive further long-term medical care at home.

CASE

The patient was a 74-year-old man with severe dysphagia due to Parkinson's disease and had a residual stomach as a consequence of a gastrectomy. He had to continue receiving long-term enteral nutrition at home, however it was difficult to create a PEG. We therefore decided to use a PTEG.

MATERIALS/METHOD

For the PTEG, a rupture-free balloon (RFB) catheter for enteral nutrition was used. First, an RFB was inserted through the nose into the esophagus and inflated. The RFB was punctured percutaneously aided by ultrasonography and conventional fluoroscopy. Then, a guide wire followed by a dilator with a sheath were inserted. Finally, an indwelling catheter was inserted into the digestive tract through the sheath.

REMARK

PTEG using an RFB catheter was a safe, simple and less invasive method; it enabled the patient to continue receiving further medical treatment at home without major complications for a long term.

A C-terminal segment with properties of alpha-helix is essential for DNA binding and in vivo function of zinc finger protein Rme1p

Rme1p plays important roles in the control of meiosis and in cell cycle progression through binding to upstream regions of IME1 and CLN2 in Saccharomyces cerevisiae. Rme1p has three zinc finger segments, and two of them are atypical. To determine DNA binding domain of Rme1p, a series of Rme1p derivatives fused with maltose-binding protein were purified and characterized by gel mobility shift assay. We show that not only three zinc fingers, but also the neighboring C-terminal region is essential for DNA binding. Mutational analysis of this region revealed that basic residues Arg-287, Lys-290, and Arg-291 and the hydrophobic residues Phe-288, Leu-292, Ile-295, and Leu-296 are critical for DNA binding. In addition, double substitutions by proline at Asn-289 and Lys-293, each of which was not essential for DNA binding, abolished DNA binding. These results suggest that the C-terminal segment forms an amphipathic helical structure. Furthermore, it was shown that the mutations in the important basic residues abolish or impair Rme1p function in vivo for repression and inhibition of spore formation. Thus, the C-terminal segment is essential and acts as a novel accessory domain for DNA binding by zinc fingers.

Sunlight induces N epsilon-(carboxymethyl)lysine formation from glycated polylysine-iron(III) complex

Sunlight was found to strongly induce the formation of N epsilon-(carboxymethyl)lysine (CML) from glycated polylysine in the presence of Fe(III) ion. The initial step of this Fe(III)-catalyzed CML formation was noted to be similar to that of blueprint photography as was confirmed by the production of Turnbull's blue in sunlight-exposed glycated human serum albumin ferricyanide solution in the presence of Fe(III). Based on this, photoinduced oxidative C-C bond cleavage of the Amadori compound was assumed to be initiated by photochemical single electron transfer front ligand to Fe(III) in the Fe(III)-Amadori compound complex affording the Fe(II)-Amadori compound radical intermediate, which eventually yields either CML or active oxygen species. CML is thus a useful oxidative stress marker. The mechanism proposed here would explain the high accumulation of CML in lens protein and skin actinic elastosis.

Modulation by dietary restriction in gene expression related to insulin-like growth factor-1 in rat muscle

Physiological adaptations induced by dietary restriction might include the modulation of the insulin-like growth factor 1 (IGF-1) axis. We investigated the effects of dietary restriction on aging-dependent changes in plasma level of IGF-1 and gene expression levels of type-1 IGF receptor (IGFR), insulin receptor substrate-1 (IRS-1), and IGF-1 in the diaphragm and quadriceps femoris muscle (QFM) of male F344 rats. The animals were fed ad libitum throughout life (AL), or provided with 70% of diet of AL rats from 6 weeks of age (DR). The plasma IGF-1 and steady-state levels of the genes were quantified by radioimmunoassay and the reverse transcription-polymerase chain reaction method, respectively. Immunohistochemical analysis in tissue sections was also performed for IGFR. Our results showed that dietary restriction: 1) decreased the plasma level of IGF-1; 2) increased the steady-state level of IGFR-mRNA at 6 and 16 months of age. and the peptide level at 6 months; 3) maintained IGF-1- and IRS-1-mRNA at a level similar to that in AL rats; and 4) delayed or inhibited an aging-dependent increase in IGFR-mRNA in the muscles. The present results suggest that dietary restriction could modulate IGF-1 signaling by augmenting local tissue response to IGF-1 and by maintaining the local production of the peptide, even though plasma IGF-1 is reduced.

Magnetization transfer measurements of the hippocampus in the early diagnosis of Alzheimer's disease

We measured magnetization transfer ratios (MTRs) of the hippocampus in 38 patients with Alzheimer's disease (AD), including very mild (Clinical Dementia Rating [CDR] 0.5, n=12), mild (CDR 1, n=14), and moderate stages (CDR 2, n=12), and in 21 healthy elderly control subjects. Medial temporal lobe atrophy was graded subjectively on a five-point scale by two observers blinded to clinical data. Compared with the controls, each of the AD groups, including the very mild group, had significant atrophy of the medial temporal lobe and a decrease in MTRs of the hippocampus. Logistic regression analysis revealed that the overall discrimination rate with MTR measurement and visual analysis of the atrophy was 85% and 73% between the control group and the CDR 0.5 group, 89% and 80% between the control group and the CDR 1 group, and 100% and 91% between the control group and the CDR 2 group, respectively. MTR measurements may provide additional information in detecting structural damage of the hippocampus of AD and be helpful in providing improved diagnosis and early detection of AD.

Magnetisation transfer measurements of the subcortical grey and white matter in Parkinson's disease with and without dementia and in progressive supranuclear palsy

We measured the magnetisation transfer ratio (MTR) in the subcortical grey and white matter of 11 patients with idiopathic Parkinson's disease (PD) without dementia, six with PD with dementia (PDD), six with progressive supranuclear palsy (PSP), and 12 elderly control subjects to assess regional differences in structural brain damage. There were no significant differences in MTR in any region between PD and controls. However, patients with PDD had significantly lower MTR in the subcortical white matter, including the frontal white matter and the genu of the corpus callosum than the controls, whereas PSP had significantly lower MTR in the subcortical grey matter, including the putamen, globus pallidus and thalamus, in addition to the subcortical white matter. This suggests that regional patterns of structural brain damage can be detected using the magnetisation transfer technique. Measurement of MTR in the subcortical grey and white matter may be useful in differential diagnosis.

Deformation and vascular occlusion of the growing rat femoral head induced by mechanical stress

To investigate the effects of mechanical stress on the extent of deformation and decrease of the blood supply to the femoral head in the growing rat, we conducted a histological and microangiographic study, using a custom-made hip-joint loading device. Application of a 1-kg to 3-kg load to the hip joint caused compression not only of the articular cartilage but also of the growth plate of the femoral head. These changes were particularly prominent in the lateral portion of the femoral head. The compression also caused complete occlusion of the lateral epiphyseal arteries, representing the blood supply to the femoral head, at the point of penetration into the epiphyseal cartilage. Our results indicate that the sum of forces during mechanical load application to the hip joint in growing rats acts to deform the cartilage of the lateral side of the femoral head. Our results also indicate the presence of a mechanically weak point in the femoral head which may lead to occlusion of the lateral epiphyseal arteries.

Separation of apple procyanidins into different degrees of polymerization by high-speed counter-current chromatography

Apple procyanidins were fractionated by high-speed counter-current chromatography in a one-step operation from apple condensed tannins using a type-J multilayer coil planet centrifuge. The separation of procyanidins was performed with a two-phase solvent system composed of methyl acetate-water (1:1) by eluting the upper phase at a flow-rate of 1.0 ml/min. Each fraction was examined by time-of-flight mass spectrometry. Procyanidins were separated according to their degrees of polymerization.

Comparative study of fat-suppressed Gd-enhanced MRI of hands in the early stage of rheumatoid arthritis (RA) and non-RA

Abstract The object of this work was to evaluate the usefulness of fat-suppressed gadolinium (Gd)-enhanced magnetic resonance imaging (MRI) for the diagnosis of early-stage rheumatoid arthritis. Forty wrists of patients who had suffered from stiff or swollen hands for 1-12 months were examined prospectively by MRI. Rheumatoid arthritis (RA) was proven in 21 patients, and the other 19 patients were not classified as having RA. Hypertrophy of the synovial membrane and tendon sheaths were evaluated by fat-suppressed Gd-enhanced MRI, and bone erosions were also evaluated by T1-enhanced MRI. These results were compared between two groups. Seventeen of 19 patients (89.5%) in the non-RA group showed little or no synovial hypertrophy, while 17 of 21 patients (81%) in the RA group showed moderate to severe hypertrophy of the synovial membrane. Little or no tenosynovitis was found in 14 of 19 patients (73.7%) in the non-RA group, while 14 of 21 patients (66.7%) in the RA group had moderate to severe tenosynovitis. No bone erosion was found in the non-RA group, while a few bone erosions were found in 10 of 21 patients (47.6%) of the RA group. Fat-suppressed, Gd-enhanced MRI was useful in differentiating early-stage RA from non-RA when all patients had some symptoms in their hands.

Apoptosis of articular chondrocytes in rheumatoid arthritis and osteoarthritis: correlation of apoptosis with degree of cartilage destruction and expression of apoptosis-related proteins of p53 and c-myc

To investigate the relationship of chondrocyte apoptosis and cartilage destruction, we performed in situ nick end labeling (ISNEL), electron microscopy, and immunohistochemistry against apoptosis-related proteins, p53 and c-myc, in the articular cartilages of patients with rheumatoid arthritis (RA; n = 12) and osteoarthritis (OA; n = 12), and in control articular cartilages from patients with femoral neck fracture (n = 8). The distribution of stained chondrocytes was evaluated semiquantitatively in relation to the degree of cartilage destruction. ISNEL-positive chondrocytes with apoptotic morphological features were identified in a relatively early phase of cartilage destruction, and correlated positively and significantly in a number with the degree of cartilage degeneration. Comparison of RA and OA revealed a significantly greater number of ISNEL-positive chondrocytes in RA cartilage. In contrast, the specimens of normal subjects contained few cells with apoptotic changes. Similarly to the distribution of ISNEL staining, the expression of p53 and c-myc proteins was observed in chondrocytes within the degraded lesions, and showed a positive correlation with the number of ISNEL-stained cells. These results suggest that the degree of chondrocyte apoptosis is closely related to cartilage destruction and that chondrocytes in RA more readily undergo apoptosis than those in OA. The expression of p53 and c-myc proteins in ISNEL-positive areas may reflect the involvement of these proteins in the apoptotic process in articular chondrocytes in inflammatory arthritis.

Increased expression of queuosine synthesizing enzyme, tRNA-guanine transglycosylase, and queuosine levels in tRNA of leukemic cells

Queuosine is a modified nucleoside located at the first position of the tRNA anticodon, which is synthesized by tRNA-guanine transglycosylase (TGT). Although the levels of queuosine in cancer cells have been reported to be lower than those in normal cells, the expression levels of TGT remain to be determined. We determined the expression levels of a subunit of TGT (TGT60KD). Contrary of our expectations, the results revealed higher levels of expression of TGT60KD than that in normal cells, and the level of queuosine in the tRNA fraction corresponded with that of TGT60KD expression. These results suggest the possibilities that the expression levels of TGT60KD regulate TGT activity and the levels of queuosine, and that TGT60KD plays significant roles in carcinogenesis. To our knowledge, this is a first report of increased expression levels of TGT60KD in human cancer cells.

High precision NMR structure of YhhP, a novel Escherichia coli protein implicated in cell division

YhhP, a small protein of 81 amino acid residues encoded by the yhhP gene in the Escherichia coli database, is implicated in cell division although the precise biological function of this protein has not been yet identified. A variety of microorganisms have similar proteins, all of which contain a common CPxP sequence motif in the N-terminal region. We have determined the three-dimensional solution structure of YhhP by NMR spectroscopy in order to obtain insight into its biological function. It folds into a two-layered alpha/beta-sandwich structure with a betaalphabetaalphabetabeta fold, comprising a mixed four-stranded beta-sheet stacked against two alpha-helices, both of which are nearly parallel to the strands of the beta-sheet. The CPxP motif plays a significant structural role in stabilizing the first helix as a part of the new type N-capping box where the Cys-Pro peptide bond adopts a cis configuration. The structure of YhhP displays a striking resemblance to the C-terminal ribosome-binding domain of translation initiation factor IF3 (IF3C). In addition, the surface charge distribution of the RNA-recognition helix of IF3C is nearly the same as that of the corresponding helix of YhhP. These results suggest a structure-based hypothesis in which binding to an RNA target plays an essential role in the function of this ubiquitous protein.

Dexamethasone inhibition of TGF beta-induced cell growth and type II collagen mRNA expression through ERK-integrated AP-1 activity in cultured rat articular chondrocytes

Intraarticular injection of dexamethasone (DEX) accelerates cartilage degradation due to the suppression of chondrocyte proliferation and extracellular matrix formation. The present study first demonstrated the interaction between DEX and TGF beta, a potent growth factor for cultured rat articular chondrocytes (CRAC), and then investigated the molecular mechanism by which DEX counteracts TGF beta-induced chondrocyte proliferation and differentiation through the regulation of AP-1 activity. DEX reduced serum-deprived and TGF beta-stimulated cell growth and [(3)H]-thymidine incorporation of CRAC. DEX also inhibited the expression of (alpha)1 type II collagen with concomitant suppression of the promoter activity. Transfection studies using a reporter vector with AP-1 responsive elements showed that DEX reduced TGF beta-activated but not basal luciferase activities. Activation of 3TP-luc, another AP-1 responsive element containing reporter was also blocked by DEX. GAL4-Elk1 studies revealed that DEX suppressed TGF beta-induced ERK activation which led to c-fos gene expression followed by increase in AP-1 complex formation, whereas the Smad pathway was not involved in DEX-dependent negative regulation of AP-1 in a reporter assay that requires FAST1-Smad2 for the activation. DEX also eliminated TGF beta-induced c-fos mRNA expression and ERK activation in Northern analysis and in vitro kinase assay, respectively. Further, DNA synthesis and transactivation of type II collagen by TGF beta were inhibited by PD98059, an inhibitor of MEK. Our results indicate that DEX suppressed TGF beta-induced chondrocyte proliferation and type II collagen expression, probably through selective inhibition of ERK integrated AP-1 activation.

Magnetization transfer measurements of the hippocampus in patients with Alzheimer's disease, vascular dementia, and other types of dementia

BACKGROUND AND PURPOSE

Although atrophy of structures in the medial temporal lobe has been considered an indication of Alzheimer's disease (AD), atrophic changes on MR images have also been associated with other dementing diseases and are not specific to AD. This study was undertaken to determine whether characteristic alterations in the hippocampus of patients with AD are detectable with magnetization transfer (MT) imaging.

METHODS

Coronal MT imaging was performed in 35 patients with probable AD, in 14 patients with vascular dementia, in 13 patients with other types of dementia, and in 23 control subjects to measure MT ratios of the hippocampus. Medial temporal lobe atrophy was graded subjectively on a five-point scale.

RESULTS

Scores of medial temporal lobe atrophy in all dementia groups were significantly higher than those in control subjects, but no differences were found among the dementia groups. MT ratios in the hippocampus were significantly lower in patients with AD than in those with non-AD dementia and in the control subjects; however, no differences were found between the non-AD dementia patients and the control subjects. MT ratio measurements were better than visual analysis of atrophy for differentiating AD patients from those with non-AD dementia (an overall discrimination rate of 77% versus 65%). MT ratios significantly correlated with scores on the Mini-Mental State Examination and with medial temporal lobe atrophy in AD patients but not in patients with non-AD dementia.

CONCLUSION

MT measurements may be more specific than visual analysis in detecting structural damage of the hippocampus in AD patients and might be useful in discriminating AD from vascular dementia and other types of dementia.

Immunohistochemical localisation of protein tyrosine kinase receptors Tie-1 and Tie-2 in synovial tissue of rheumatoid arthritis: correlation with angiogenesis and synovial proliferation

OBJECTIVE

To investigate the involvement of Tie-1 and Tie-2, receptor tyrosine kinases required for angiogenesis, in synovial proliferation and angiogenesis of rheumatoid arthritis (RA).

METHODS

Synovial tissues from 10 patients with RA and three control subjects were analysed by double immunohistochemistry and reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTS

Expression of Tie-1 and Tie-2 was seen in all synovia, but predominantly in papillary projected portions. In synovial lining cells, Tie-2 was expressed mainly in the basal layer and frequently colocalised with vimentin and proliferating cell nuclear antigen (PCNA), whereas Tie-1 was also expressed in the superficial layer. In stromal cells, Tie-2 immunoreactivity was restricted to vimentin positive fibroblast-but not macrophage derived cells, whereas Tie-1 expression was not dependent on the phenotype. Tie receptors were also highly expressed in the endothelium and surrounding pericytes of capillaries scattered over the papillary proliferated synovium without notable difference in the expression of the two receptors. Furthermore, Tie positive vessels often overexpressed PCNA. In normal synovia, expression of Tie receptors was restricted to the capillary endothelium. RT-PCR confirmed the expression of Tie-1 and Tie-2 in RA synovial tissues and also in the cultured synoviocytes.

CONCLUSION

The results suggest the possible involvement of overexpressed Tie-1 and Tie-2 in synovial lining and stromal cells in the pathophysiology of RA synovitis, probably through distinct mechanisms. Furthermore, expression of Tie receptors in actively growing vasculature may reflect the direct involvement of these receptors in angiogenesis and subsequent vascularisation.

High-speed counter-current chromatography of apple procyanidins

Apple procyanidins were separated by high-speed counter-current chromatography using a type-J multilayer coil planet centrifuge. Several two-phase solvent systems with a wide range of hydrophobicities from a non-polar hexane system to polar n-butanol systems were evaluated their performance in terms of the partition coefficient and the retention of the phase. The best separation of procyanidins B and C was achieved with a two-phase solvent system composed of n-butanol-methyl tert.-butyl ether-acetonitrile-0.1% trifluoroacetic acid (2:4:3:8) using the lower phase as a mobile at a flow-rate of 1.0 ml/min.

A role of the C-terminal region adjacent to the zinc-fingers in the DNA binding ability of Rme1p, a regulator of meiosis in S. cerevisiae

Rme1p is a zinc-finger protein and has a pivotal role in control of meiosis in Saccharomyces cerevisiae. The DNA binding domain of Rme1p consists of three zinc-finger segments and the C-terminal 16 amino acid residues (called C-TR). To examine the role of C-TR, a series of mutant Rme1p fused with maltose binding protein (MBP) were constructed, purified, and characterized, in terms of the DNA binding ability. The basic amino acid residues R287 and K290, and the hydrophobic residues F288, L292, 1295, and L296 play an important role for DNA binding, suggesting that the C-TR forms an amphipathic alpha-helix. Also, it was shown that the mutations in the basic amino acid residues abolish the repression and inhibition of spore formation by Rme1p in vivo. Hence, the C-TR is important for in vivo function of Rme1p.

Destabilization of nucleosomes by an unusual DNA conformation adopted by poly(dA) small middle dotpoly(dT) tracts in vivo

Poly(dA) small middle dotpoly(dT) tracts are common and often found upstream of genes in eukaryotes. It has been suggested that poly(dA) small middle dotpoly(dT) promotes transcription in vivo by affecting nucleosome formation. On the other hand, in vitro studies show that poly(dA) small middle dotpoly(dT) can be easily incorporated into nucleosomes. Therefore, the roles of these tracts in nucleosome organization in vivo remain to be established. We have developed an assay system that can evaluate nucleosome formation in yeast cells, and demonstrated that relatively longer tracts such as A(15)TATA(16) and A(34) disrupt an array of positioned nucleosomes, whereas a shorter A(5)TATA(4) tract is incorporated in positioned nucleosomes of yeast minichromosomes. Thus, nucleosomes are destabilized by poly(dA) small middle dotpoly(dT) in vivo in a length-dependent manner. Furthermore, in vivo UV footprinting revealed that the longer tracts adopt an unusual DNA structure in yeast cells that corresponds to the B' conformation described in vitro. Our results support a mechanism in which a unique poly(dA) small middle dot poly(dT) conformation presets chromatin structure to which transcription factors are accessible.

Differential effects of IGF-binding proteins, IGFBP-3 and IGFBP-5, on IGF-I action and binding to cell membranes of immortalized human chondrocytes

Insulin-like growth factor-I (IGF-I) is an important anabolic factor for cartilage tissue and its action is, in part, regulated by IGF-binding proteins (IGFBPs). The object of this study was to investigate the effects of IGFBPs on IGF-I action and on binding of IGF-I to cells using a reproducible immortalized human chondrocyte culture model. Treatment of the C-28/I2 cells with IGF-I or des(1-3)IGF-I in serum-free medium stimulated cell proliferation in a dose-dependent manner. However, the effect of des(1-3)IGF-I was more potent, thereby suggesting that endogenously produced IGFBPs inhibited IGF action. The stimulatory effect of IGF-I was inhibited significantly by addition of IGFBP-3 but enhanced slightly by IGFBP-5. However, neither IGFBP-3 nor IGFBP-5 had an effect on basal cell growth. Binding of (125)I-labeled IGF-I to the cells was displaced by both IGFBP-3 and IGFBP-5, although higher concentrations of unlabeled IGFBP-5 were required to displace IGF-I to the same extent as IGFBP-3. Treatment of the cells with IGF-I increased the levels of IGFBP-5 protein measured by Western ligand blotting, and stimulated a corresponding increase in IGFBP-5 mRNA while increasing type II collagen mRNA. Our findings indicate that the balance between IGFBP-3 and IGFBP-5 influences IGF receptor binding and its action on chondrocyte proliferation, and may thereby modulate cartilage metabolism.