The association of plasma adiponectin level with carotid arterial stiffness

Adiponectin plays important roles in protecting against both insulin resistance and the development of atherosclerosis. The aim of the present study was to investigate the clinical impact of plasma adiponectin on arterial stiffness, a functional property of atherosclerosis, in type 2 diabetic and nondiabetic subjects. We evaluated plasma adiponectin levels and stiffness index beta for the common carotid artery assessed by ultrasound using a phase-locked echo-tracking system for 98 type 2 diabetic subjects and 116 nondiabetic subjects as controls. Plasma adiponectin levels were significantly lower in the diabetic than in the nondiabetic group. The stiffness index beta was significantly higher in the diabetic than in the nondiabetic group. Plasma adiponectin level was significantly correlated with stiffness index beta in the group of all subjects (r=-0.189, P=.006) and the nondiabetic group (r=-0.187, P=.045), but not in the diabetic group (r=0.045, P=.665). On multiple regression analysis, plasma adiponectin level was found to be a significant independent contributor to stiffness index beta in the group of all subjects (beta=-0.232, P=.020) and the nondiabetic group (beta=-0.337, P=.016), but not in the diabetic group. In conclusion, adiponectin is significantly but weakly associated with carotid arterial stiffness independently of known atherogenic factors in the nondiabetic group and that of all subjects, although no significant association between these variables was found in the group of diabetic subjects.

Expression of FGF23 is correlated with serum phosphate level in isolated fibrous dysplasia

Fibrous dysplasia (FD) patients sometimes suffer from concomitant hypophosphatemic rickets/osteomalacia, resulting from renal phosphate wasting. It was recently reported that FD tissue in the patients with McCune-Albright syndrome (MAS) expressed fibroblast growth factor-23 (FGF-23), which is now known to be as a pathogenic phosphaturic factor in patients with oncogenic osteomalacia and X-linked hypophosphatemic rickets. Since it remains controversial whether serum phosphate levels are influenced by FGF23 expressions in FD tissue, isolated FD patients without MAS syndrome were examined for the relationship between FGF23 expressions, circulating levels of FGF-23 and phosphate to negate the effects of MAS-associated endocrine abnormalities on serum phosphate. Eighteen paraffin embedded FD tissues and 2 frozen tissues were obtained for the study. Sixteen of 18 isolated FD tissues were successfully analyzed GNAS gene, which exhibited activated mutations observed in MAS. Eight of 16 FD tissues, which exhibited GNAS mutations, revealed positive staining for FGF-23. These evidence indicate that postzygotic activated mutations of GNAS is necessary for the FD tissue formation by mosaic distribution of mutated osteogenic cell lineage, but is not sufficient to elevate FGF23 expression causing generalized osteomalacia with severe renal phosphate wasting. The expression level of FGF23 in isolated FD tissue with hypophosphatemic osteomalacia determined by real-time PCR was abundant close to the levels in OOM tumors. Osteoblasts/osteocytes in woven bone were predominant source of circulating FGF-23 in FD tissues by immunohistochemistry. A negative correlation of the intensity of FGF-23 staining with serum inorganic phosphate levels indicated that the expression of FGF23 in focal FD tissues could be a prominent determinant of serum phosphate levels in isolated FD patient. These data provide novel insights into the regulatory mechanism of serum inorganic phosphate levels in isolated FD patients and extend the notion that FGF-23 originating from FD tissue may cause hypophosphatemia not only in isolated FD patients but also in the patients with MAS syndrome.

Paraarticular trabecular bone loss at the ultradistal radius and increased arterial stiffening in postmenopausal patients with rheumatoid arthritis

OBJECTIVE

We recently reported enhanced arterial thickening in patients with rheumatoid arthritis (RA) and the importance of increased bone resorption in this process. Our aim was to examine whether arterial stiffening, another aspect of atherosclerosis, is also increased in patients with RA, and to determine if it is an important risk factor.

METHODS

The subjects were 47 patients with RA and 49 healthy controls, all postmenopausal women. Subjects having risk factors for atherosclerosis were excluded. Femoral-ankle (fa) pulse wave velocity (PWV) and brachial-ankle (ba) PWV were measured in all patients using a waveform analyzer. Bone mineral density (BMD) at the ultradistal radius was assessed by peripheral quantitative computed tomography. Inflammation markers (C-reactive protein, erythrocyte sedimentation rate, rheumatoid factor, platelet count) and bone resorption markers (urinary excretion of deoxypyridinoline and N-terminal telopeptide) were also measured.

RESULTS

The median values of faPWV and baPWV in RA patients were 1124 cm/s [interquartile range (IQR) 1040-1175] and 1539 cm/s (IQR 1297-1738), respectively, which were significantly greater than the respective values of 982 cm/s (IQR 819-1054; p < 0.001) and 1322 cm/s (IQR 1112-1398; p = 0.004) in controls. In multiple regression analysis, the presence of RA emerged as an independent factor associated with the greater faPWV and baPWV when adjusted for age, blood pressure, and smoking. In RA patients alone, BMD in the trabecular bone component, but not for the total bone (cortical plus trabecular), at the ultradistal radius correlated significantly with both faPWV and baPWV. Multiple regression analysis showed that trabecular BMD at the distal radius was a significant factor independently associated with greater faPWV and baPWV when adjusted for age, blood pressure, and smoking. None of the measured inflammation markers or bone resorption markers correlated with either faPWV or baPWV in patients with RA.

CONCLUSION

Patients with RA show increased arterial stiffening, in addition to the arterial thickening we have previously reported, supporting the notion of enhanced atherosclerosis in RA patients. Paraarticular bone loss in the trabecular bone component at the ultradistal radius is a factor significantly associated with increased arterial stiffening in RA patients.

Platelet-monocyte aggregates are independently associated with occurrence of carotid plaques in type 2 diabetic patients

Recent evidence suggests important roles for platelet activation in the progression of atherosclerosis. We have recently shown that P-selectin expression or the presence of platelet-monocyte aggregates, a well-characterized marker of platelet activation, is associated with carotid atherosclerosis in the general population. It is not clear, however, whether platelet activation is also associated with carotid atherosclerosis in patients with type 2 diabetes. In the present study, we measured circulating levels of platelet-monocyte aggregates in 120 patients with type 2 diabetes and 120 age- and gender-matched non-diabetic subjects, and examined their association with carotid atherosclerosis determined by arterial ultrasound. The percentage of platelet-monocyte aggregates was analyzed by CD41-positivity determined by whole-blood flow cytometry. Diabetic subjects (7.73 +/- 4.04%, mean +/- SD) showed significantly higher percentages of platelet-monocyte aggregates than non-diabetic subjects (6.03 +/- 4.38%). The percentage of these aggregates was significantly and positively correlated with HbA(1c) in both diabetic and non-diabetic subjects, with the association independent of other clinical factors. Logistic multiple regression analyses revealed that platelet-monocyte aggregates were significantly associated with the presence of carotid plaques independent of the status of glycemic control in diabetic subjects. Thus, an increase in platelet-monocyte aggregation in type 2 diabetic patients appears to be involved in the pathophysiology of carotid atherosclerosis.

SREBP inhibits VEGF expression in human smooth muscle cells

Sterol regulatory element-binding proteins (SREBPs) are transcription factors that regulate expression of genes encoding enzymes for lipid biosynthesis. SREBPs are activated by HMG-CoA reductase inhibitors (statins). Statins have been also reported to suppress vascular endothelial growth factor (VEGF) expression in vascular smooth muscle cells (VSMCs). Therefore, we hypothesized that SREBPs are involved in statin-mediated regulation of VEGF production in VSMCs. SREBP1 was robustly expressed, and was activated by atorvastatin in VSMCs, as demonstrated by increased levels of the mature nuclear form of SREBP1, and increased promoter activities of a reporter containing sterol regulatory elements by atorvastatin. Moreover, overexpression of SREBP1a dose-dependently suppressed VEGF promoter activity. Site-specific mutation or deletion of the proximal Sp1 sites reduced the inhibitory effects of SREBP1a on VEGF promoter activity. These data demonstrated that SREBP1, activated by atorvastatin, suppressed VEGF expression through the indirect interaction with the proximal tandem Sp1 sites in VSMCs.

Positive correlation of serum bio-intact PTH(1-84) but not intact PTH with parathyroid gland size in hemodialysis patients

To evaluate the usefulness of newly-developed bio-intact parathyroid hormone (Bio-PTH) assay, which measures exclusively intact PTH(1-84) molecule, serum PTH level determined by Bio-PTH assay, in comparison with second-generation intact PTH (I-PTH) assay, was examined for its correlation with parathyroid gland size. Serum PTH was determined in 46 male HD patients, together with bone formation markers bone alkaline phosphatase, intact osteocalcin, N-terminal propeptide of type I collagen, and bone resorption markers deoxypyridinoline, pyridinoline, beta-crossLaps. Maximal diameter of parathyroid gland was determined with ultrasonography as the parathyroid gland size. Serum Ca and Pi correlated significantly with parathyroid gland size rationalizing our method to define parathyroid gland size. Serum Bio-PTH was correlated significantly in a positive manner with parathyroid gland size (R = 0.308, P = 0.0474), whereas serum I-PTH did not. Furthermore, parathyroid gland size did not exhibit a significant correlation with any of bone formation markers or bone resorption markers. The lack of correlation between bone markers and parathyroid gland size in HD patients may be explained by the occurrence of refractoriness of bone to PTH. In conclusion, serum Bio-PTH assay could provide a better assay than I-PTH assay to estimate parathyroid function in HD patients, due mainly to its exclusive correlation with parathyroid gland size.

Effect of atorvastatin on regional arterial stiffness in patients with type 2 diabetes mellitus

OBJECTIVE

A statin, a potent lipid-lowering drug, improves pain-free walking distance in patients with peripheral arterial disease (PAD) without increasing the ankle-brachial pressure index (ABI). Arterial stiffness affects the blood flow of peripheral arteries. The purpose of this study was to evaluate the effect of cholesterol-lowering with atorvastatin on regional arterial stiffness in patients with type 2 diabetes mellitus.

METHODS

The subjects were 22 type 2 diabetic patients with hypercholesterolemia, who received atorvastatin at a daily dose of 10 mg for 6 months. Before and after the treatment with atorvastatin, we measured pulse wave velocity (PWV) in the heart-brachial, heart-carotid, heart-femoral and femoral-ankle segments.

RESULTS

Following treatment with atorvastatin, femoral-ankle PWV showed a significant reduction. The PWV of other arterial segments tended to decrease, although the changes were not statistically significant. We found no significant changes in blood pressure, heart rate, ABI, or plasma concentrations of glucose, L-arginine and asymmetric dimethylarginine (ADMA), an endogenous inhibitor of endothelial function.

CONCLUSIONS

Atorvastatin treatment was associated with an improvement in the stiffness of leg arteries in type 2 diabetes mellitus. This may partly explain the statin-mediated improvement of walking performance in those with PAD.

Plasma adiponectin level is associated with insulin-stimulated nonoxidative glucose disposal

CONTEXT

Impaired nonoxidative glucose disposal and decrease in mitochondrial glucose oxidation both contribute to insulin resistance in diabetic subjects.

OBJECTIVE

In the present study, we investigated whether plasma adiponectin is associated with glucose oxidation and nonoxidative glucose disposal in subjects with and without type 2 diabetes.

DESIGN

Euglycemic-hyperinsulinemic clamp was performed in 42 type 2 diabetic (T2DM) and 13 nondiabetic (non-DM) subjects. The whole-body glucose disposal rate (GDR) was evaluated as the mean of the glucose infusion rate during steady state of the clamp. Glucose and fat oxidation rates were assessed by indirect calorimetry, and nonoxidative glucose disposal rate was calculated by subtracting glucose oxidation rate from GDR.

RESULTS

Plasma adiponectin level was significantly lower in T2DM than non-DM (2.87 +/- 1.40 vs. 3.96 +/- 2.39 microg/ml, P = 0.045). GDR (3.39 +/- 1.53 vs. 4.83 +/- 1.70 mg/kg x min, P = 0.006) and nonoxidative glucose disposal rate (1.89 +/- 1.39 vs. 3.11 +/- 1.76 mg/kg x min, P = 0.012) were significantly lower in T2DM, compared with non-DM, although no difference was found in glucose oxidation rate between the two groups. In all subjects, plasma adiponectin level was positively correlated with GDR (r = 0.351, P = 0.009) and nonoxidative glucose disposal rate (r = 0.324, P = 0.016) but not glucose oxidation rate. There was no significant correlation between plasma adiponectin level and fat oxidation, either before or during the clamp.

CONCLUSIONS

In conclusion, plasma adiponectin level is associated with nonoxidative glucose disposal, which is reduced in type 2 diabetic subjects. Our results suggest that adiponectin controls insulin sensitivity by modulating the glycogen synthetic process in human skeletal muscle.

Increased pulse wave velocity in subclinical hypothyroidism

OBJECTIVE

Subclinical hypothyroidism affects 5-15% of the general population and is associated with increased morbidity from cardiovascular disease. Brachial-ankle pulse wave velocity (baPWV) is a parameter of arterial stiffening and a good independent predictor for the presence of coronary artery disease. This study was performed to assess whether subclinical hypothyroidism might cause enhanced baPWV.

PATIENTS AND METHODS

baPWV was examined in subclinical hypothyroid patients (n = 50) and normal control subjects (n = 50).

RESULTS

Diastolic blood pressure (DBP), a main risk factor for cardiovascular disease, and baPWV were both significantly higher in subclinical hypothyroid patients than normal subjects. baPWV was significantly positively correlated with age and systolic, diastolic, and pulse pressure and significantly negatively correlated with pulse rate in both subclinical hypothyroid patients and normal subjects. In contrast, there was no significant correlation of baPWV with free T3, free T4, TSH, total, high-density lipoprotein- and low-density lipoprotein-cholesterol, and the preejection time to ejection time ratio. A comparison of individual values of baPWV and DBP and regression slopes in two groups revealed that baPWV values increase to a larger extent than the increase in DBP in subclinical hypothyroid patients. In both groups, stepwise regression analysis showed a significant and independent association of DBP with baPWV.

CONCLUSIONS

The present study demonstrated significant increases of baPWV and DBP in subclinical hypothyroid patients. Furthermore, the results suggest that increased DBP might be one of the main factors responsible for increased arterial stiffening in subclinical hypothyroid patients.

Direct in vitro evidence of the suppressive effect of cinacalcet HCl on parathyroid hormone secretion in human parathyroid cells with pathologically reduced calcium-sensing receptor levels

Clinical studies have been performed to determine the effect of cinacalcet HCl (cinacalcet), an allosteric modulator of the calcium-sensing receptor (CaR), on primary hyperparathyroidism (PHPT) and secondary hyperparathyroidism of uremia (SHPT). However, no in vitro studies on human parathyroid cells have been reported to date. In this study, the inhibitory effect of cinacalcet on PTH secretion was analyzed in primary cultured parathyroid cells obtained from patients. The investigation involved three PHPT and three SHPT patients subjected to therapeutic parathyroidectomy. Notably, all SHPT patients were resistant to intravenous vitamin D analogue therapy. Removed parathyroid tumors were used for immunohistochemistry and parathyroid cell primary culture. Immunohistochemical analyses revealed diminished expression of CaR and vitamin D receptor (VDR) in all parathyroid tumors. PTH secretion from cultured parathyroid cells of PHPT and SHPT patients was suppressed by extracellular Ca2+ and cinacalcet in a dose-dependent manner. Rates of suppression of PTH secretion in PHPT and SHPT by cinacalcet (1000 nmol/l) were 61% +/- 21% and 61% +/- 19%, respectively. Cinacalcet demonstrates significant potency in the suppression of PTH secretion in primary cultured human parathyroid cells in vitro, despite reduced levels of the target protein, CaR. Data from this in vitro analysis support the clinical application of cinacalcet in PHPT and SHPT therapy.

Regulation of plasma fibroblast growth factor 23 by calcium in primary hyperparathyroidism

OBJECTIVE

While the importance of fibroblast growth factor (FGF)-23 is established in phosphate-wasting disorders, little is known about the mechanisms regulating its circulating level. To investigate the role of parathyroid hormone (PTH) and calcium in FGF-23 metabolism, we examined plasma FGF-23 levels in patients with primary hyperparathyroidism (PHPT).

PATIENTS AND METHODS

Fifty patients with PHPT and 52 controls were employed in this study. Plasma was obtained from 18 PHPT patients who underwent parathyroidectomy (PTX) on the first postoperative morning without vitamin D administration. Time-course samples were also obtained from 5 of 18 PTX patients without vitamin D analogs or calcium administration. The expression of Fgf23 on resected parathyroid glands was analyzed by reverse transcription (RT)-PCR and immunohistochemistry.

RESULTS

FGF-23 was significantly elevated in PHPT patients compared with controls. FGF-23 levels were significantly correlated positively with serum corrected calcium and intact PTH levels, and negatively with creatinine clearance and inorganic phosphate, among which creatinine clearance and corrected calcium were independently associated factors. In 18 PTX patients, postoperative FGF-23 levels were significantly decreased compared with preoperative levels. Corrected-calcium levels were significantly decreased 1 h after PTX, and this was followed by a reduction in plasma FGF-23 levels in time-course study. In addition, postoperative FGF-23 levels in 18 PTX patients were significantly correlated with corrected calcium, consistent with a role of serum calcium as one of the major regulators of FGF-23. The absence of Fgf23 expression in parathyroid glands indicated that the parathyroid glands were not major sources of circulating FGF-23.

CONCLUSIONS

Serum calcium may regulate circulating FGF-23 levels in PHPT.

Vascular calcification in chronic kidney disease

Vascular calcification is often encountered in advanced atherosclerotic lesions and is a common consequence of aging. Calcification of the coronary arteries has been positively correlated with coronary atherosclerotic plaque burden, increased risk of myocardial infarction, and plaque instability. Chronic kidney disease (CKD) patients have two to five times more coronary artery calcification than healthy age-matched individuals. Vascular calcification is a strong prognostic marker of cardiovascular disease mortality in CKD patients. Vascular calcification has long been considered to be a passive, degenerative, and end-stage process of atherosclerosis and inflammation. However, recent evidence indicates that bone matrix proteins such as osteopontin, matrix Gla protein (MGP), and osteocalcin are expressed in calcified atherosclerotic lesions, and that calcium-regulating hormones such as vitamin D3 and parathyroid hormone-related protein regulate vascular calcification in in vitro vascular calcification models based on cultured aortic smooth muscle cells. These findings suggest that vascular calcification is an actively regulated process similar to osteogenesis, and that bone-associated proteins may be involved in the development of vascular calcification. The pathogenesis of vascular calcification in CKD is not well understood and is almost multifactorial. In CKD patients, several studies have found associations of both traditional risk factors, such as hypertension, hyperlipidemia, and diabetes, and uremic-specific risk factors with vascular calcification. Most patients with progressive CKD develop hyperphosphatemia. An elevated phosphate level is an important risk factor for the development of calcification and cardiovascular mortality in CKD patients. Thus, it is hypothesized that an important regulator of vascular calcification is the level of inorganic phosphate. In order to test this hypothesis, we characterized the response of human smooth muscle cell (HSMC) cultures to inorganic phosphate levels. Our findings indicate that inorganic phosphate directly regulates HSMC calcification through a sodium-dependent phosphate transporter mechanism. After treatment with elevated phosphate, there is a loss of smooth muscle lineage markers, such as alpha-actin and SM-22alpha, and a simultaneous gain of osteogenic markers such as cbfa-1 and osteocalcin. Elevated phosphate may directly stimulate HSMC to undergo phenotypic changes that predispose to calcification, and offer a novel explanation of the phenomenon of vascular calcification under hyperphosphatemic conditions. Furthermore, putative calcification inhibitory molecules have been identified using mouse mutational analyses, including MGP, beta-glucosidase, fetuin-A, and osteoprotegerin. Mutant mice deficient in these molecules present with enhanced cardiovascular calcification, demonstrating that specific molecules are normally important in suppressing vascular calcification. These findings suggest that the balance of inducers, such as phosphate, and inhibitors, such as MGP, fetuin-A, and others, are likely to control whether or not calcification occurs under pathological conditions.

The significance of thyroid blood flow at the inferior thyroid artery as a predictor for early Graves' disease relapse

OBJECTIVE

We investigated the clinical usefulness of thyroid blood-flow measurement in predicting relapse of Graves' disease (GD) in comparison with known risk factors for GD relapse.

MEASUREMENT

Thyroid blood flow was measured in pulsed Doppler mode at the inferior thyroid artery (ITA), and the peak systolic velocity (PSV) calculated.

PATIENTS

ITA-PSV was measured in euthyroid GD patients (n = 79) immediately before withdrawal of anti-thyroid drug (ATD) and in healthy subjects (n = 17).

RESULTS

In the 79 euthyroid GD patients, the values of free triiodothyronine (FT3), TSH receptor autoantibody (TRAb), ITA-PSV and thyroid volume were significantly higher in the relapse group (n = 40) than in the nonrelapse group (n = 39) and the Youden index of ITA-PSV was significantly higher than that of FT3, TSH, TRAb and vascular endothelial growth factor (VEGF).

CONCLUSION

ITA-PSV may assist in the prediction of early GD relapse after ATD withdrawal.

Plasma levels of adiponectin and soluble thrombomodulin in hypothyroid patients with normal thyroid function following levothyroxine replacement therapy

Hypothyroidism is associated with increased morbidity from cardiovascular disease, and adiponectin (ApN) is a newly-identified adipocytokine, which is expressed in human adipose cells and may have a protective effect against the development of coronary artery disease. The aim of the study was to evaluate the involvement of ApN secretion in hypothyroid patients with normal thyroid function following levothyroxine (L-T(4)) replacement therapy, and to associate plasma ApN levels with intima-media thickness (IMT) in the common carotid artery (CCA), an indicator of early atherosclerosis, and cardiovascular parameters including soluble thrombomodulin (sTM), a plasma endothelial injury marker. The CCA IMT and plasma levels of ApN and sTM were measured in 52 hypothyroid patients and in age-, sex- and body mass index (BMI)-matched normal control subjects. Thirty-six of the hypothyroid patients were further monitored for changes in these markers during 1 year in a euthyroid state induced by L-T(4) replacement therapy. Although the basal CCA IMT was significantly higher in hypothyroid patients [0.633 +/- 0.018 mm (mean +/- S.E.)] than in control subjects (0.552 +/- 0.022 mm, P < 0.005), both groups had similar baseline ApN and sTM levels [10.23 +/- 0.76 vs. 10.10 +/- 0.93 microg/ml: NS; and 2.58 +/- 0.14 vs. 2.68 +/- 0.20 ng/ml: NS, respectively]. Simple regression analysis revealed that plasma ApN was significantly correlated in a positive manner with age (r = 0.339, P = 0.015), HDL-cholesterol (r = 0.295, P = 0.048), and sTM (r = 0.490, P = 0.0005), but not with CCA IMT (r = 0.059, P = 0.742). In multivariate analysis, the plasma ApN level was significantly associated with that of sTM (r = 0.546, P = 0.0001) and with serum high-density lipoprotein (HDL)-cholesterol levels (r = 0.291, P = 0.029) in hypothyroid patients. During 1 year of L-T(4) replacement therapy, hypothyroid patients showed a significant decrease in CCA IMT, to 0.553 +/- 0.016 mm (P < 0.0001), a level comparable to normal controls, but no significant change in ApN (from 10.79 +/- 1.07 to 10.6 9+/- 1.14 microg/ml, NS) or sTM (from 2.59 +/- 0.15 to 2.74 +/- 0.18 ng/ml, NS). Hence, we provide evidence that ApN and sTM might not contribute to enhanced atherosclerosis, as reflected by increased CCA IMT in hypothyroid patients. However, this is the first report to demonstrate a positive and significant association of sTM with ApN. These data support the hypothesis that sTM is one of the determinant of ApN and thus suggest the presence of an sTM-associated regulatory mechanism for ApN secretion in hypothyroid patients.

Cimetidine-induced tubulointerstitial nephritis with both MPO-ANCA and PR3-ANCA

We describe a 75-year-old man with tubulointerstitial nephritis (TIN) with myeloperoxidase (MPO)-antineutrophil antibody (ANCA) and proteinase-3 (PR3)-ANCA. He had a slight fever and eruption with itching after taking cimetidine (prescribed after gastrectomy for gastric cancer) and he was admitted to a nearby hospital. There, he showed proteinuria, serum creatinine (sCr) of 2.9 mg/dl, and creatinine clearance (Ccr) of 44 ml/min per 1.73 m2. His MPO-ANCA titer was 267 EU, and PR3-ANCA titer was 112 EU. Abnormal concentrations in bilateral kidneys were found by gallium scintigraphy. For these reasons, he was transferred to our hospital. Percutaneous renal biopsy was performed after admission. Severe tubular atrophy, mild interstitial fibrosis, and severe mononuclear cell infiltration of the interstitium were noted. Drug-induced renal impairment was suspected, and cimetidine administration was withdrawn. Lymphocyte stimulation tests (DLSTs) were performed. The cimetidine titer was positive, at 2,537 cpm. After the withdrawal of cimetidine, the PR3-ANCA titer was reduced gradually, and, next, the MPO-ANCA titer was also reduced. The sCr level was reduced to 1.2 mg/dl. In summary, we report herein the first case of cimetidine-induced TIN associated with both MPO-ANCA and PR3-ANCA.

Associations between physical activity, peripheral atherosclerosis and bone status in healthy Japanese women

The aim of this cross-sectional study was to investigate whether physical activity and bone status may affect arterial thickening and stiffening in healthy Japanese women. Healthy women (n = 149; mean age, 54 years) were recruited from those who participated in a local health check program at the Osaka City University Hospital. Physical activity was assessed by physical functioning score of SF-36, and bone status by bone mineral density (BMD) in lumbar spine and calcaneus osteo-sono index (OSI). Arterial wall thickening assessed by intima-media thickness (IMT) in common carotid artery (CA) and femoral artery (FA), and arterial wall stiffening by peak wave velocity (PWV) in heart-carotid (hc) and heart-femoral (hf) as central segment and in heart-brachial (hb) and femoral-ankle (fa) as peripheral segment, respectively. By Spearman Rank correlation, lumbar spine BMD was correlated negatively with CA IMT (rho = -0.225, p < 0.05) and FA IMT (rho = -0.215, p < 0.05), and calcaneus OSI with FA IMT (rho = -0.330, p < 0.0001) but not CA IMT (rho = -0051, p = 0.5335). Both lumbar spine BMD and calcaneus OSI correlated negatively with PWV in all segments (all p < 0.05). Physical functioning score correlated weakly but significantly in a negative manner with all PWV segments (all p < 0.05) but not IMT. Multiple regression analyses revealed a significant association of calcaneus OSI (beta = -0.240, p = 0.0039) but not lumbar spine BMD (beta = -0.067, p = 0.4541) with FA IMT, although neither lumbar spine BMD nor calcaneus OSI was associated with CA IMT. Furthermore, physical functioning score was independently associated with hb and fa PWV but not hc and hf PWV, suggesting the preferential association with peripheral segment including lower extremities. Neither lumbar spine BMD nor calcaneus OSI was associated with any segment of PWV. In conclusion, it was suggested that calcaneus OSI might be associated with arterial wall thickening preferentially in femoral artery, and that physical activity may be associated with arterial wall stiffening in peripheral segment including lower extremity but not in central segment in healthy Japanese women.

Serum Levels of 1–84 and 7–84 Parathyroid Hormone in Predialysis Patients with Chronic Renal Failure Measured by the Intact and Bio-PTH Assay

BACKGROUND

The intact parathyroid hormone (PTH) assay detects both PTH(1-84) and the PTH(7-84)-like fragment, which is reported to be an antagonist of the biological action of PTH(1-84). It is debatable which of the two assays is clinically more useful, the intact or bio-PTH assay, the latter of which only detects PTH(1-84). It is also unknown whether serum levels of the PTH(7-84)-like fragment have clinical significance.

METHODS

Serum PTH concentrations in 104 predialysis patients with chronic renal failure (CRF; serum creatinine 3.53 +/- 1.93; 62 males and 42 females; 61.0 +/- 11.5 years old) were measured using both the intact and bio-PTH assays, and the concentration of the PTH(7-84)-like fragment was calculated by subtracting bio-PTH from intact PTH. Three bone formation and three bone resorption markers were measured simultaneously.

RESULTS

The PTH values measured using the two assays were strongly positively correlated (r = 0.959, p < 0.0001), and were also significantly positively correlated with the three bone formation and three bone resorption markers to a similar degree. The PTH(7-84)-like fragment was significantly positively correlated with both the intact and bio-PTH (r = 0.855, p < 0.0001 for intact PTH; r = 0.672, p < 0.0001 for bio-PTH), and was also significantly positively correlated with each of the six bone metabolism markers. There is no significant relationship between the bio-PTH/PTH(7-84)-like fragment ratio and clinical parameters including bone metabolic markers.

CONCLUSION

From the strong relationship between the two assays, and the similar degree of the relationship between each PTH assay and each of the six bone metabolism markers, it is considered that the bio-PTH and intact PTH assays have similar clinical significance in predialysis CRF patients. Serum levels of the PTH(7-84)-like fragment seem to increase as serum PTH(1-84) increases. The results suggest that the serum PTH(7-84)-like fragment has little specific clinical effect on bone metabolism, even when assessed by the ratio of bio-PTH/PTH(7-84)-like fragment.

[Analysis of factors for progression of diabetic renal failure in elderly people]

AIM

To investigate the factors in the progression of renal failure in type 2 diabetes in elderly people.

MATERIALS AND METHODS

The subjects were 2034 patients hospitalized for type 2 diabetes therapy at Osaka City University Hospital from 1993 to 2000. Among them, 362 patients had diabetic non-dialyzed renal failure. Moreover, 93 patients reached the endpoint of doubling primary serum creatinine values. We analyzed the factors of progression for diabetic renal failure, and divided the cohorts into two groups. One group consisted of patients 65 years old or more (higher age group, HP), and the other of patients under 65 years old (lower age group, LP). We used the Kaplan-Meier methods and Cox proportional hazard models for the analysis of the cohorts with the endpoint of doubling the serum creatinine values.

RESULTS

There were no significant differences between HP and LP by the Kaplan-Meier methods for progression of renal failure. According to Cox monofactorial-analysis, hypoalbuminemia was determined to be a significant factor in the progression of renal failure in both HP and LP. In the Cox multifactorial-analysis, hypoalbuminemia was a independent significant factor in HP, but not in LP.

CONCLUSION

Hypoalbuminemia is considered to be a significant factor in the progression of renal failure in type 2 diabetes regardless of age, and may be a more significant factor in elderly people.

Detection of a point mutation in FAS2 gene of sake yeast strains by allele-specific PCR amplification

To identify yeast mutants with a point mutation, detection of the specific mutant alleles is necessary. For this purpose, we applied allele-specific polymerase chain reaction (PCR) to detect the FAS2-1250S dominant mutant allele that encodes an altered fatty acid synthase in Japanese brewer's yeast strains. These strains are known to produce a higher amount of ethyl caproate in Japanese sake. The mutant strains were supposed to be diploid and to contain heterozygous alleles, including wild-type FAS2 and a dominant FAS2-1250S. A set of oligonucleotide primers was designed to contain different nucleotides at their 3' termini: one type was identical to the wild type and the other to the mutant FAS2. Another set of primers was designed to have an additional mismatch at the second nucleotide from their 3' termini. By testing with control strains, we established PCR conditions for specific amplification. Using these conditions and a simple template preparation procedure with SDS, the presence of the allele was detected in commercially used sake yeast strains. The method presented here will be useful for the identification of specific yeast strains.

Effect of glycine on 5-aminolevulinic acid biosynthesis in heterotrophic culture of Chlorella regularis YA-603

Chlorella regularis strain YA-603 was previously found to exhibit a comparatively high growth rate and improved 5-aminolevulinic acid (ALA) productivity when cultured heterotrophically. Although the universal tetrapyrrole precursor ALA is synthesized from glutamate in algae and higher plants, in this study the addition of glutamate to the medium did not enhance ALA production in the heterotrophic culture of C. regularis YA-603. On the other hand, the addition of glycine, which is a precursor of ALA biosynthesis via the Shemin pathway in animal cells and some bacteria, enhanced both the specific growth rate and ALA production. Moreover, when a second glycine addition was made during the culture, the ALA concentration increased by about 1.5 times compared to that obtained with one glycine addition. From these results, it is suggested that the Shemin pathway contributes to ALA production, and that addition of glycine in the heterotrophic culture of C. regularis YA-603 can significantly increase the amount of ALA produced.

Construction of recombinant sake yeast containing a dominant FAS2 mutation without extraneous sequences by a two-step gene replacement protocol

A novel two-step gene replacement protocol was developed to construct a recombinant industrial yeast free of bacterial and drug-resistant marker sequences. A yeast strain exhibiting cerulenin resistance conferred by a dominant mutation of FAS2 was previously shown to produce high levels of a flavor component of Japanese sake. A N- and C-terminally truncated portion of the mutant FAS2 gene was subcloned to an integrating plasmid containing an aureobasidin A-resistant transformation marker and a galactose-inducible growth inhibitory sequence (GAL10p::GIN11). The plasmid was targeted into the chromosomal FAS2 locus of sake yeast Kyokai no. 7, resulting in a tandem repeat of inactive FAS2 sequences surrounding the integrated plasmid sequences. Cells containing the integrated plasmid were unable to grow on galactose medium due to the inhibitory effect of GAL10p::GIN11. This growth inhibition allowed efficient counter-selection for cells that had undergone homologous recombination between the FAS2 repeats by their growth on galactose medium. This recombination event resulted in loss of the integrated plasmid sequences and the resulting strains should contain a single copy of either wild-type or cerulenin-resistant FAS2. The selected cerulenin-resistant strains produced approximately 3.7-fold more ethyl caproate, a flavor component, than the Kyokai no. 7 strain. Southern blot and sequence analyses confirmed the presence of the FAS2 mutation and the absence of integrated plasmid sequences in the genome of the selected strain. This gene replacement method provides a straightforward approach for the construction of recombinant industrial yeasts free of undesirable DNA sequences.

Serum concentrations of cross-linked N-telopeptides of type I collagen: new marker for bone resorption in hemodialysis patients

BACKGROUND

Urinary cross-linked N-telopeptide of type I collagen (NTX) is a reliable bone resorption marker in patients with metabolic bone disease. We assessed a clinically available serum NTX assay suitable for anuric patients on hemodialysis (HD).

METHODS

Serum concentrations of NTX, C-terminal telopeptide of type I collagen (beta-CTX), pyridinoline (PYD), and deoxypyridinoline (DPD) were determined as bone resorption markers, and those of bone alkaline phosphatase (BAP) and intact osteocalcin (OC) as bone formation markers, in 113 male HD patients (mean age, 59.3 years; mean HD duration, 67.7 months). Each patient's bone mineral density (BMD) in the distal third of the radius was measured twice, with a 2-year interval between measurements, by dual-energy x-ray absorptiometry.

RESULTS

Serum NTX correlated significantly with beta-CTX, PYD, DPD, BAP, and intact OC. NTX, as well as beta-CTX, PYD, DPD, BAP, and intact OC, correlated significantly with BMD at the time of measurement. NTX, beta-CTX, and DPD correlated significantly with the annual change in BMD during the 2-year period thereafter, in contrast to PYD, BAP, and intact OC. Patients in the highest quartile of serum NTX concentrations showed the fastest rate of bone loss. The sensitivity and specificity for detecting rapid bone loss were 48% and 83%, respectively, for serum NTX.

CONCLUSION

Serum NTX may provide a clinically relevant serum assay to estimate bone turnover in HD patients.

Cross-sectional association of serum phosphate with carotid intima-medial thickness in hemodialysis patients

BACKGROUND

Although an increased serum phosphate concentration is a significant risk factor for vascular calcification, it is unclear whether serum phosphate level is a risk factor for increased arterial wall thickness in hemodialysis patients.

METHODS

Using B-mode ultrasonography, we examined intima-medial thickness (IMT) of the carotid artery of hemodialysis patients and analyzed risk factors for increased IMT with regard to the effect of serum phosphate. Seven hundred sixteen hemodialysis patients were enrolled (547 patients without diabetes, 169 patients with diabetes; 441 men, 275 women; age, 60 +/- 8.5 years).

RESULTS

IMT of patients with diabetes was significantly greater than that of patients without diabetes (0.859 +/- 0.250 versus 0.783 +/- 0.178 mm; P < 0.0001). For the group of all patients, IMT correlated weakly, but significantly, with serum phosphate level (r = 0.093; P = 0.0127). In multiple regression analysis of the group of all patients, greater serum phosphate level (beta = 0.166; P < 0.0001) was shown to be a significant independent risk factor for increased carotid IMT, in addition to other significant independent risk factors, including advanced age, higher blood pressure, greater non-high-density lipoprotein cholesterol level, and the presence of diabetes (R2 = 0.1119; P < 0.00001). In multiple regression analyses performed separately for hemodialysis patients without and with diabetes, greater phosphate level and advanced age were significant independent risk factors for increased IMT, independent of other confounding risk factors.

CONCLUSION

These results show that in addition to advanced age, greater serum phosphate level is a significant and independent factor associated with advanced arteriosclerosis in hemodialysis patients with and without diabetes, suggesting that phosphate levels should be controlled appropriately to prevent an increase in arterial wall thickness in hemodialysis patients.

Plasma level of endogenous secretory RAGE is associated with components of the metabolic syndrome and atherosclerosis

OBJECTIVE

Advanced glycation endproducts, AGEs, and its specific receptor, RAGE, are involved in diabetic vascular complications. Endogenous secretory RAGE, esRAGE, has been identified as an alternatively spliced form of RAGE, and shown to act as a decoy receptor for AGE. Here, we measured plasma esRAGE level with a recently developed enzyme-linked immunosorbent assay (ELISA) and examined its association with atherosclerosis in age- and gender-matched 203 type 2 diabetic and 134 nondiabetic subjects.

METHODS AND RESULTS

Plasma esRAGE was inversely associated with carotid or femoral atherosclerosis, as quantitatively measured as intimal-medial thickness (IMT) by arterial ultrasound. Stepwise regression analyses revealed that plasma esRAGE was the third strongest and independent factor associated with carotid IMT, following age and systolic blood pressure. Plasma esRAGE was significantly lower in diabetic patients (0.176+/-0.092 ng/mL) than nondiabetic controls (0.253+/-0.111). Of note, in all, diabetic or nondiabetic group, plasma esRAGE was significantly and inversely correlated with components of the metabolic syndrome including body mass index, blood pressure, triglyceride, HbA1c, or an insulin resistance index. Stepwise regression analyses showed that body mass index or insulin resistance index was the major factor determining plasma esRAGE in all, nondiabetic or diabetic population.

CONCLUSIONS

esRAGE is a novel and potential protective factor for the metabolic syndrome and atherosclerosis.

Relationship between parathyroid calcium-sensing receptor expression and potency of the calcimimetic, cinacalcet, in suppressing parathyroid hormone secretion in an in vivo murine model of primary hyperparathyroidism

Cinacalcet HCl, an allosteric modulator of the calcium-sensing receptor (CaR), has recently been approved for the treatment of secondary hyperparathyroidism in patients with chronic kidney disease on dialysis, due to its suppressive effect on parathyroid hormone (PTH) secretion. Although cinacalcet's effects in patients with primary and secondary hyperparathyroidism have been reported, the crucial relationship between the effect of calcimimetics and CaR expression on the parathyroid glands requires better understanding. To investigate its suppressive effect on PTH secretion in primary hyperparathyroidism, in which hypercalcemia may already have stimulated considerable CaR activity, we investigated the effect of cinacalcet HCl on PTH-cyclin D1 transgenic mice (PC2 mice), a model of primary hyperparathyroidism with hypo-expression of CaR on their parathyroid glands. A single administration of 30 mg/kg body weight (BW) of cinacalcet HCl significantly suppressed serum calcium (Ca) levels 2 h after administration in 65- to 85-week-old PC2 mice with chronic biochemical hyperparathyroidism. The percentage reduction in serum PTH was significantly correlated with CaR hypo-expression in the parathyroid glands. In older PC2 mice (93-99 weeks old) with advanced hyperparathyroidism, serum Ca and PTH levels were not suppressed by 30 mg cinacalcet HCl/kg. However, serum Ca and PTH levels were significantly suppressed by 100 mg/kg of cinacalcet HCl, suggesting that higher doses of this compound could overcome severe hyperparathyroidism. To conclude, cinacalcet HCl demonstrated potency in a murine model of primary hyperparathyroidism in spite of any presumed endogenous CaR activation by hypercalcemia and hypo-expression of CaR in the parathyroid glands.

Direct in vitro evidence of extracellular Ca2+-induced amino-terminal truncation of human parathyroid hormone (1-84) by human parathyroid cells

CONTEXT

Although serum calcium (Ca2+) concentration regulates the generation of amino-terminally (N-terminally) truncated forms of human PTH (hPTH) degraded from (1-84)hPTH, no studies have yet reported whether the parathyroid gland itself is responsible for this process.

OBJECTIVE

Our objective was to determine the site of N-terminal truncation and its roles in PTH metabolism in parathyroid cells in vitro.

METHODS

The effect of extracellular Ca2+ concentration was examined on N-terminal truncation in primary cultured parathyroid cells. The parathyroid glands were obtained from the patients with primary and uremia-associated secondary hyperparathyroidisms who underwent therapeutic parathyroidectomies.

RESULTS

The N-terminally truncated fragments were detectable with commercially available intact PTH (I-PTH) assays, but not with the bio-intact PTH (Bio-PTH) assay, which detected only the (1-84)hPTH. HPLC revealed that generation of N-terminally truncated fragments detectable by I-PTH increased with extracellular Ca2+ concentration. Suppression of PTH secretion by increasing the extracellular Ca2+ concentration was more evident with the Bio-PTH assay than with the I-PTH assay for both cultured parathyroid cells prepared from parathyroid adenomas and uremia-associated secondary hyperparathyroidism. The Bio-PTH/I-PTH ratio, which is the ratio of (1-84)hPTH to the sum of (1-84)hPTH and N-terminally truncated fragments, decreased in response to increases in extracellular Ca2+.

CONCLUSIONS

These findings suggest that the N-terminal truncation is regulated by extracellular Ca2+ concentration and works to suppress the generation of (1-84)hPTH in parathyroid cells.

[Correlation of serum Bio-intact PTH (1-84) and parathyroid gland size in hemodialysed patients]

Bio-intact parathyroid hormone (Bio-PTH) assay, which measures exclusively intact PTH (1-84) molecule, provides a better assay for estimating parathyroid function in hemodialysis (HD) patients, whereas intact PTH (I-PTH) assay cross-react with PTH (7-84) as well as PTH (1-84). We have found that PTH (7-84) accumulated into serum of hemodialysis patients due probably to its impaired excretion into urine. We have reported that parathyroid gland size is one of major predictor for vitamin D responsiveness in secondary hyperparathyroidism. Therefore, we investigated whether serum Bio-PTH, in comparison with serum I-PTH, may provide a relevant assay to estimate parathyroid function as evidence by its correlation with parathyroid gland size on ultrasound examination.

[Effects of parathyroid hormone gene polymorphism on cardiovascular mortality]

It is well-known that secondary hyperparathyroidism of uremia influences not only bone and mineral metabolism but also cardiovascular complications. Here we reported the effects of the level of serum intact PTH and its gene polymorphism on cardiovascular and non-cardiovascular mortality in hemodialysis patients. We analyzed the association between clinico-molecular parameters and 3-year survival in 508 hemodialysis patients among whom 90 patients died. The multivariate Cox proportional hazards models showed that the presence of diabetes mellitus, levels of albumin and intact PTH, and BstB I genotype were indicated as independent predictors of cardiovascular mortality, whereas age and albumin level were indicated as those of non-cardiovascular mortality, suggesting that the level of intact PTH and its gene polymorphism effect cardiovascular mortality in hemodialysis patients.

[Significance of serum PTH (7-84) as a reliable nutritional marker in hemodialysis patients]

To evaluate the significance of serum PTH (7-84) in hemodialysis patients, correlation of the serum PTH (7-84) level with various nutritional markers was investigated in HD patients. Serum PTH was determined in 170 male HD patients by either a Bio intact PTH assay or a second-generation intact PTH assay. The level of bone formation markers and bone resorption markers were also measured. Lean body mass in trunk region was measured by dual X-ray absorptiometry. The serum PTH (7-84) level was obtained for the difference between serum I-PTH and Bio-PTH. Serum PTH (1-84) was directly obtained from the serum Bio-PTH value. Serum PTH (7-84) correlated significantly with nutritional markers such as body weight, albumin, PCR, TAC BUN, BUN, phosphate and lean body mass in trunk, whereas PTH (1-84) only correlated with phosphate. The correlation of serum PTH (7-84) with bone metabolic markers was no less significant than that for PTH (1-84). The results suggest that serum level of PTH (7-84) may provide clinically useful information, not only of the bone metabolic state but also of the nutritional state in HD patients, in sharp contrast to the exclusive correlation of PTH (1-84) with bone metabolic state.

[Vascular calcification in advanced secondary hyperparathyroidism]

Cardiovascular disease is one of the largest cause of mortality in maintenance hemodialysis patients. Vascular calcifications frequently encountered in hemodialysis patients. In advanced uremic secondary hyperparathyroidism model mice, vascular calcifications were observed in their aorta, by Kossa staining. This mouse model may be a useful model to study vascular calcification in maintenance hemodialysis patients.

[Acute response of serum PTH and bone markers after injection of 1alpha,25 (OH)2D3 and 22-oxacalcitrol in hemodialysis patient]

Time-course changes of serum PTH and various bone markers were compared after injection of 1alpha,25 (OH)(2)D(3) with that of 22-oxacalcitriol (OCT) in hemodialysis patients. Five patients (M/F; 3/2, mean ages of 61.6 years) were enrolled into the present study. Oral administration of vitamin D(3) derivatives was stopped at least one week before initiation of vitamin injection. After 1 week of single intravenous injection of OCT (5 microg), 1alpha,25 (OH)(2)D(3) (0.5 microg) was followed. Serum levels of intact PTH, intact osteocalcin, bone alkaline phosphatase, cross-linked N-telopeptides of type I collagen, calcium, and phosphate were measured before, 24h, and 48 h after injections of vitamin D(3) derivatives. Significant difference did not exist in time-course changes of serum PTH, any of bone markers, calcium and phosphate between after OCT and 1alpha,25 (OH)(2)D(3) injection. In conclusion, the present study may not support the presence of significant direct effect of vitamin D(3) derivatives on bone metabolism in hemodialysis patients.

[Clinical significance of PTH (1-84) and PTH (7-84) in patients with predialysis chronic renal failure in relation to bone metabolism markers]

Serum levels of parathyroid hormone (PTH) in predialysis patients with chronic renal failure (CRF) were measured using both the "intact PTH" and "bio PTH" assays, and serum levels of PTH (7-84) were assessed by subtracting bio PTH from intact PTH. The PTH values measured by the two assays were strongly correlated, and were also significantly positively correlated with both bone formation and resorption markers. PTH (7-84) was significantly positively correlated with both the intact PTH and bio PTH, and was also significantly positively correlated with the bone metabolism markers. There is no significant relationship between bio PTH/PTH (7-84) ratio and bone metabolism markers. In conclusion, bio PTH and intact PTH assays have similar clinical significance in predialysis CRF patients. The PTH (7-84) and even the ration of bio-PTH/PTH (7-84) have little specific clinical effect on bone metabolism.

[Effect of calcium on N-terminal truncation of PTH in human parathyroid cells]

Serum PTH (7-84) is accumulated in patients with secondary hyperparathyroidism. It is also known that serum calcium (Ca) increases the generation of N-terminally truncated forms of parathyroid hormone (PTH). In this study, we examined whether accumulation of PTH (7-84) fraction is a parathyroid glandular origin or not by using primary cultured parathyroid cells from patients with primary and secondary hyperparathyroidism. The Bio-PTH/I-PTH ratio, indicating the ratio of PTH (1-84) to the sum of (1-84) PTH and N-terminally truncated fragment, was suppressed by increase in extracellular Ca2+ concentration for both cultured parathyroid cells prepared from parathyroid adenomas and uremia-associated secondary hyperparathyroidism. There is no difference between the ratios in primary and secondary hyperparathyroidism. These findings suggest that N-terminal truncation is regulated by extracellular Ca2+ concentration in parathyroid cells, but accumulation of PTH (7-84) fragments in patients with secondary hyperparathyroidism is mainly caused by uremia.

Aortic calcification in haemodialysis patients with diabetes mellitus

BACKGROUND

Certain metabolic disorders, such as hyperphosphatemia induce vascular calcification in haemodialysis patients; it is unclear, however, whether these disorders contribute to aortic calcification in diabetic haemodialysis patients. This study examined the risk factors of aortic calcification in a large number of haemodialysis patients, and compared risk factors between diabetic and non-diabetic patients.

METHODS

The subjects were 667 patients on maintenance haemodialysis: 184 with type 2 diabetes and 483 without. Aortic calcification was measured semi-quantitatively using a plain computed tomography image of the abdominal aorta, and an aortic calcification index (ACI) was calculated.

RESULTS

The ACI of the diabetic subjects was significantly higher than that of those without diabetes (57.3+/-22.1 vs 44.8+/-28.3%, P < 0.0001), although the dialysis vintage of the former was significantly shorter (P < 0.001). Multiple regression analyses showed that diabetes was a significant independent risk factor for increased ACI. Multiple regression analyses, performed separately in diabetics and non-diabetics, revealed that advanced age, higher systolic blood pressure, smoking and longer haemodialysis vintage were common independent risk factors significantly associated with increased ACI in both patient groups (R2 = 0.296, P < 0.0001 for non-diabetics; R2 = 0.193, P < 0.0001 for diabetics). Higher serum phosphate concentration was not significantly associated with increased ACI in diabetic patients (P = 0.429), although it was a significant independent factor in non-diabetic patients (beta = 0.150, P < 0.0005).

CONCLUSION

Aortic calcification in diabetic haemodialysis patients is more advanced, compared with non-diabetic patients, even with short haemodialysis vintage. Since disorders of mineral metabolism are not significantly associated with aortic calcification in diabetic haemodialysis patients, aortic calcification in these patients could be affected by metabolic abnormalities associated with the diabetic state per se, independent of other confounding factors; and aortic calcification may be advanced even before haemodialysis induction.

Introduction to Sevelamer Hydrochloride and its Clinical Effects

Sevelamer hydrochloride (SH) is widely used for the treatment of hyperphosphatemia in patients with renal failure who are on maintenance hemodialysis. In this study, we investigated the clinical effects of SH, administered as either monotherapy or combined with a calcium carbonate formulation, on the metabolism of calcium (Ca) and phosphorus (P) in patients who had been taking a Ca-based binder. Patients were divided into three groups (i): switched completely from a Ca-based binder to SH (complete switch); (ii) dosage of the Ca-based binder was reduced, and SH introduced (partial switch); and (iii) dosage of the Ca-based binder was not reduced and SH introduced (combination therapy). We also examined the effects of the introduction of SH on the lipid profile and parathyroid hormone (PTH) concentration. Comparison between groups of the numbers of successfully treated cases (reaching target concentrations of serum P=5.5 mg/dL and Ca x P product=55 mg2/dL2 within 6 months of treatment) showed that the likelihood of reaching target levels was higher if Ca-based binder was maintained as much as possible (combination therapy>partial changeover>complete changeover). Furthermore, treatment with SH decreased total cholesterol and non-HDL cholesterol concentrations significantly, and also increased HDL cholesterol and PTH concentrations compared to pre-treatment. These results suggest that when a calcium carbonate formulation is already in use, as far as compliance allows, the dosage should not be reduced when SH is added. Despite its beneficial effects on the lipid and PTH concentrations, preventing an excessive increase in the PTH concentration is essential when using SH.

Serum BAP as the clinically useful marker for predicting BMD reduction in diabetic hemodialysis patients with low PTH

With decrease of serum PTH in hemodialysis (HD) patients, other factors besides parathyroid hormone (PTH) become important in regulating bone metabolism. We investigated which serum bone metabolic marker is the best to predict the bone mineral density (BMD) reduction in HD patients with serum PTH<180 pg/ml. The bone formation markers, bone alkaline phosphatase (BAP), intact osteocalcin (OC), and N-terminal propeptide of type I collagen (PINP), and the bone resorption markers, deoxypyridinoline (DPD), pyridinoline (PYD), and beta-crossLaps (beta-CTx) were measured in serum from 137 HD patients. BMD of all patients was measured twice, approximately 1.5 years before and 1.5 years after measurement of their markers of bone metabolism. In all 137 HD patients, serum BAP was the only marker significantly higher in those with BMD reduction than in those without. In 42 diabetes mellitus (DM) HD patients with serum PTH<180 pg/ml, hypothetically low bone turnover state, serum BAP was again the only marker to discriminate those with BMD reduction from those without. At serum PTH<60 pg/ml, serum BAP retained tendency toward higher value. These findings suggest that serum BAP might be the most sensitive to identify small changes of bone metabolism in low bone turnover state. Retrospective study confirmed the usefulness of serum BAP in clinical practice by significantly higher values in those with bone loss at PTH<180 pg/ml even in under routine sample handling. In conclusion, serum BAP is a clinically useful bone formation marker to predict the BMD reduction in DM HD patients with low level of PTH.

C-reactive protein is a significant predictor of decrease in fat mass in hemodialysis patients

Malnutrition and inflammation are common in hemodialysis patients, and are usually closely associated. We examined annual body fat mass changes, a possible nutritional parameter, in maintenance hemodialysis patients, and investigated the factors affecting such changes. Body fat mass of 454 hemodialysis patients (61+/-11 years, 269 males and 185 females) was measured twice by dual energy X-ray absorptiometry (DEXA), with a 12-month interval between measurements. In a total of 65 patients with hemodialysis duration of less than 1 year at the first measurement, fat mass at the second measurement had increased significantly over the course of a year (P<0.0001). In contrast, in a total of 389 patients with hemodialysis duration of more than 1 year at the first measurement, fat mass at the second measurement significantly decreased (P<0.005). In the 389 patients, significant negative correlations were seen between fat mass changes and CRP (r=-0.165, P<0.005). In a multiple regression analysis, CRP was a significant factor (beta=-0.163, P<0.005) affecting fat mass changes, independent of other confounding clinical factors (R(2)=0.127, P<0.001). These results show that body fat mass of long-term hemodialysis patients decreases after an initial increase in the first to second years of hemodialysis. In hemodialysis patients, fat mass change appears to be a parameter indicative of nutritional changes. Chronic inflammation, represented by higher CRP levels, is a significant factor affecting decrease in fat mass, and is related to poorer nutritional status.

Insulin resistance index as a predictor for pioglitazone treatment in type 2 diabetes

BACKGROUND

It is difficult to predict the hypoglycemic effect of pioglitazone (a thiazolidinedione) as an insulin sensitizer. The purpose of the present study was to investigate whether insulin resistance index, homeostasis model assessment index (HOMA-IR) is a useful predictor of hypoglycemic effect of pioglitazone in comparison with body mass index (BMI).

METHODS

Thirty-four type 2 diabetic patients (14 men and 20 women, mean age 60 +/- 14 years) were treated with pioglitazone, 15 mg per day for 3 months. Eighteen subjects showed a decrease of 0.5% or more in HbA1C after treatment and were considered responders while 16 subjects were non-responders. A receiver operating characteristic (ROC) analysis was performed to determine HOMA-IR and BMI sensitivity and the false positive rate (1-specificity) for discriminating responders from non-responders.

RESULTS

Although there was no significant difference in age, sex, fasting plasma glucose, HbA1C and BMI between responders and non-responders, fasting insulin levels and HOMA-IR prior to treatment were significantly higher in the responders than in the non-responders. In ROC analysis, the sensitivity, false positive rate, and efficiency for HOMA-IR at the cut-off value, 4.6, with the highest efficiency were 81.2%, 22.2%, and 79.4%, respectively, and those for BMI at the cut-off value, 29.1, were 87.5%, 53.3%, and 67.7%, respectively.

CONCLUSION

HOMA-IR is a useful predictor of pioglitazone treatment in type 2 diabetic patients.

Suppression of PI3K/mTOR pathway rescues LLC cells from cell death induced by hypoxia

Cancer cells in solid tumors are challenged by various microenvironmental stresses, including hypoxia, and cancer cells in hypoxic regions are resistant to current cancer therapies. To investigate the mechanism of resistance to hypoxia in cancer cells, we examined mouse Lewis lung carcinoma (LLC) cells, which died due to necrosis at high density under hypoxic but not under normoxic conditions. Levels of mammalian target of rapamycin (mTOR), a central regulator of cellular energy, are reported to be suppressed in hypoxia. We found that phosphorylation of two molecules downstream to it, ribosomal p70 S6 kinase (S6K) and ribosomal protein S6, was markedly suppressed by hypoxia. Overexpression of the active form of S6K increased the sensitivity of LLC cells to hypoxia. On the other hand, inhibition of PI3K or mTOR dramatically reduced hypoxia-induced cell death under hypoxic conditions. Under hypoxic conditions, blockade of the PI3K or mTOR pathway increased levels of intracellular ATP and delayed decreases in pH and glucose level in culture medium, without affecting the cell cycle.

Significance of Bio-intact PTH(1-84) assay in hemodialysis patients

The aim of the present study was to examine whether the newly developed bio-intact parathyroid hormone (Bio-PTH) assay, which exclusively measures the intact PTH(1-84) molecule, provides a better assay for estimating parathyroid function in hemodialysis (HD) patients, and to evaluate the factors associated with serum PTH levels measured by Bio-PTH assay and by second-generation intact PTH (I-PTH) assay. The study also examined whether Bio-PTH/I-PTH ratio, an index of the active fraction of PTH, could provide information not obtainable from simple PTH results. Serum levels of PTH were measured in 177 male HD patients, together with the bone formation markers bone alkaline phosphatase (BAP), intact osteocalcin (iOC), N-midfragment osteocalcin (N-Mid OC), and N-terminal propeptide of type I collagen (PINP), and the bone resorption markers deoxypyridinoline (DPD), pyridinoline (PYD), and beta-CrossLaps (beta-CTx). Bone mineral density (BMD) was determined twice at distal radius one-third by dual-energy X-ray absorptiometry. Serum Bio-PTH was significantly elevated in HD patients compared to normal controls. Serum Bio-PTH and I-PTH correlated significantly in a positive manner with serum bone formation markers (BAP, iOC, N-Mid OC, PINP), and resorption markers (DPD, PYD, beta-CTx), and in a negative manner with BMD and annual change therein at distal radius one-third. The degree of correlation of Bio-PTH was not significantly different from that of I-PTH. The Bio-PTH/I-PTH ratio was significantly lower in HD patients than in normal individuals, due probably to accumulation of N-truncated PTH fragments in the former. The Bio-PTH/I-PTH ratio correlated significantly in a negative manner with serum calcium (Ca) (r=-0.251, P<0.001) and nutritional marker serum urea nitrogen, protein catabolic rate and serum creatinine. Multiple regression analysis further revealed that serum I-PTH, but not Bio-PTH, was significantly associated with each of these nutritional markers, and that the Bio-PTH/I-PTH ratio was negatively associated with serum Ca. It was also found that I-PTH, but not Bio-PTH, was influenced by nutritional state. It is concluded that serum Bio-PTH assay could be of similar value to I-PTH assay in evaluating parathyroid function in HD patients and that their combined use in the form of the Bio-PTH/I-PTH ratio could provide information not obtainable from simple PTH results.

Platelet in progression of atherosclerosis: a potential target in diabetic patients

Altered platelet function reported in diabetic patients appears to be involved in the pathogenesis of diabetic vascular complications. However until recently, the role of platelets in progression of spontaneous atherosclerosis remained questionable. The original version of the response to injury hypothesis, where deposited platelets at denuded endothelium play key roles in the spontaneous development of atherosclerosis, has been modified dramatically over the past three decades; atherogenesis is now considered a chronic inflammatory process in which monocytes and T cells play central roles. Recently however, evidence has been accumulated that activated platelet contributes to progression of atherosclerosis in apo E-deficient mice. Activated platelets aggregate with leukocytes, release proinflammatory cytokines, chemokines and growth regulatory molecules, resulting in endothelial activation, leukocyte recruitment and altered smooth muscle cell function. Indeed, it has been shown that activated platelets, and their aggregates with leukocytes are found in the circulation of patients with coronary artery diseases. We have recently shown that circulating P-selectin positive platelets, which are higher in diabetic patients than non-diabetic subjects, are significantly and positively associated with carotid atherosclerosis in the large-scale human studies. This review will focus on altered platelet function in diabetic patients, and its implications in the progression of atherosclerosis.

Serum levels of C-terminal telopeptide of type I collagen: a useful new marker of cortical bone loss in hemodialysis patients

Renal osteodystrophy is a major complication in hemodialysis patients. Measurement of serum peptide derived from the degradation of bone collagen could potentially provide an indirect estimate of bone resorption. The present study estimated the significance of the C-terminal telopeptide of type I collagen (beta-CTx) as a serum bone resorption marker in male hemodialysis patients. The mean age and hemodialysis duration of the 160 patients were 59.7 years (26-86 years) and 67.2 months (17-142 months), respectively. Bone mineral density (BMD) in the distal third of the radius was measured using dual-energy X-ray absorptiometry twice with a 2-year interval. A blood sample was collected immediately before the hemodialysis session at the time of the second BMD measurement. Other serum bone markers determined were bone-specific alkaline phosphatase (BAP) and intact and N-terminal midfragment (N-Mid) osteocalcin (OC) as bone-formation markers and serum pyridinoline (PYD) and deoxypyridinoline (DPD) as bone resorption markers. Serum beta-CTx correlated significantly in a positive manner with serum PYD, DPD, BAP, intact OC, and N-Mid OC. Serum beta-CTx, as well as PYD, DPD, BAP, intact OC, and N-Mid OC, correlated significantly with BMD in the distal third of the radius at the second measurement and with the rate of BMD reduction during the preceding 2 years. The highest quartile of serum beta-CTx was positively associated with rapid bone loss, defined as a change in the value for BMD in the distal third of the radius falling within the upper tertile of patients, in 55% of cases, and each quartile progress in serum beta-CTx increased the odds ratio of rapid bone loss by a factor of 1.73. Since the Youden index was twice as accurate for beta-CTx, BAP and N-Mid OC as for intact PTH, these bone-remodeling markers may be better risk markers of cortical bone loss than intact PTH. Inclusion in the highest quartile of PTH (above 288 pg/ml) predicted rapid bone loss with a sensitivity of only 26%. This means that the upper limit for serum PTH level recommended by K/DOQI may be too high, since 74% of cases with rapid bone loss showed serum PTH levels of below 288 pg/ml. In conclusion, serum measurement of beta-CTx may provide a new commercially viable and relevant serum assay to reflect cortical bone resorption in hemodialysis patients.