Monthly Archives: March 2014

Low LDL Associated with Fractures in Hyperparathyroidism

Abstract

Low density lipoprotein-cholesterol levels affect vertebral fracture risk in female patients with primary hyperparathyroidism.

Although increased arterial sclerosis and dyslipidemia were observed in primary hyperparathyroidism (pHPT) patients in previous studies, it still remains unclear about the relationships between lipid and bone metabolism in pHPT patients, especially about fracture risk. The present study was performed to examine the relationships between lipid metabolism parameters including body composition and bone metabolism in 116 female patients with pHPT and 116 age-matched control subjects. Bone mineral density (BMD) and body composition were measured by dual-energy x-ray absorptiometry. Serum low density lipoprotein (LDL)-cholesterol (Chol) levels were negatively related to only z-score of BMD at femoral neck and serum creatinine levels. Serum levels of LDL-Chol were significantly lower in the group with vertebral fractures in pHPT patients, although body composition parameters were not significantly different. In univariate logistic regression analyses, age, height, BMD at lumbar spine and radius, serum levels of creatinine, total-Chol and LDL-Chol were significantly selected as a predictor of vertebral fractures. LDL-Chol was related to vertebral fractures independently of the other parameters. In conclusion, the present study demonstrated that lower serum LDL-Chol levels were related to vertebral fracture risk independent of renal function, age, body size, bone metabolism parameters and the severity of the disease in pHPT women.

Kaji H, Hisa I, Inoue Y, Sugimoto T
Exp. Clin. Endocrinol. Diabetes Jun 2010
PMID: 19609845

LDL Impairs Osteoblast Differentiation

Abstract

Oxidized low density lipoprotein inhibits phosphate signaling and phosphate-induced mineralization in osteoblasts. Involvement of oxidative stress.

It is well admitted that oxidized LDL (OxLDL) plays a major role in the generation and progression of atherosclerosis. Since atherosclerosis is often accompanied by osteoporosis, the effects of OxLDL on phosphate-induced osteoblast mineralization were investigated.
Calcium deposition, expression of osteoblast markers and inorganic phosphate (Pi) signaling were determined under OxLDL treatment.
OxLDL, within the range of 10-50 μg protein/ml, inhibited Pi-induced UMR106 rat osteoblast mineralization. In parallel, the expression of Cbfa1/Runx2 transcription factor was decreased, and the intracellular level of the osteoblast marker osteopontin (OPN) was reduced. The extracellular level of another marker, receptor activator of nuclear factor kappa B ligand (RANKL), was also diminished. OxLDL inhibited Pi signaling via ERK/JNK kinases and AP1/CREB transcription factors. OxLDL triggered the generation of reactive oxygen species (ROS), either in the absence or presence of Pi. Furthermore, the effects of OxLDL on Pi-induced mineralization, generation of ROS and extracellular level OPN were reproduced by the lipid extract of the particle, whereas the antioxidant vitamin E prevented them.
This work demonstrates that OxLDL, by generation of an oxidative stress, inhibits of Pi signaling and impairs Pi-induced osteoblast differentiation.
This highlights the role of OxLDL in bone remodeling and in degenerative disorders other than atherosclerosis, especially in osteoporosis.

Mazière C, Savitsky V, Galmiche A, Gomila C…
Biochim. Biophys. Acta Nov 2010
PMID: 20667472

LDL, HDL, and Triglyceride Correlations with Bone Density in Postmenopausal Women

Abstract

Plasma lipids and osteoporosis in postmenopausal women.

Many clinical studies have shown that osteoporosis is associated with atherosclerosis and cardiovascular death. Although both high plasma levels of low density lipoprotein cholesterol (LDL-C) and low plasma levels of high density lipoprotein cholesterol (HDL-C) are known to be risk factors for atherosclerosis, it is unclear whether such lipid derangements are also associated with the pathogenesis of osteoporosis. In this study, we evaluated the relationships between plasma levels of total C, LDL-C, HDL-C, or triglyceride (TG) versus bone mineral density (BMD) at the lumbar spine, femoral neck, radius, or total body as well as the presence of vertebral fractures in 214 Japanese postmenopausal women (age range, 47-86 years, mean 62.7). Multiple regression analysis was performed between BMD at each skeletal site versus each lipid level adjusted for age, years after menopause, body mass index (BMI), and %fat. Plasma LDL-C levels were significantly and inversely correlated with the absolute values of both one-third radial (1/3R) and distal radial (UDR) BMD (p<0.01), and tended to be inversely correlated with the absolute values of L-BMD (p=0.051). In contrast, plasma HDL-C levels were significantly and positively correlated with the absolute values of L, 1/3R and UDR BMD (p<0.05). On the other hand, plasma TG levels were significantly lower in women with vertebral fractures than in those without fractures (97.0+/-36.5 vs. 126.4+/-65.8 mg/dl, mean+/-SD, p<0.05). When multivariate logistic regression analysis was performed with the presence of vertebral fractures as a dependent variable and each lipid level adjusted for age, years after menopause, BMI, and %fat as independent variables, TG alone was selected as an index affecting the presence of vertebral fractures (odds ratio: 0.51, 95% confidential interval: 0.29-0.89 per SD increase, p<0.05). Our study showed that plasma LDL-C and HDL-C levels were inversely and positively correlated with both R- and L-BMD values, respectively, while low plasma TG levels were associated with the presence of vertebral fractures in postmenopausal women. Thus, plasma lipids might be related to bone mass and bone fragility, and might be the common factor underlying both osteoporosis and atherosclerosis.

Yamaguchi T, Sugimoto T, Yano S, Yamauchi M…
Endocr. J. Apr 2002
PMID: 12081241 | Free Full Text

AKG Decreases a Marker of Bone Turnover in Postmenopausal Women with Osteopenia

Abstract

Alpha-ketoglutarate decreases serum levels of C-terminal cross-linking telopeptide of type I collagen (CTX) in postmenopausal women with osteopenia: six-month study.

Several studies have shown that alpha-ketoglutaric acid (AKG) increases serum levels of proline and has beneficial effects on skeletal development. We studied the effect of alpha-ketoglutaric (AKG) acid calcium salt (6 g AKG and 1.68 Ca/day) or calcium alone (1.68 Ca/day) on serum C-terminal cross-linked telopeptide of type I collagen (CTX) and osteocalcin (OC), as well as on lumbar spine bone mineral density (BMD) in a randomized, parallel group, double-blind, 6-month study conducted on 76 postmenopausal women with osteopenia. The maximum decrease of the mean CTX level in the AKG-Ca group was observed after 24 weeks (37.0%, p = 0.006). The differences in CTX between study groups were statistically significant after 12 and 24 weeks. The OC serum level was not affected by treatments. The BMD of the AKG-Ca group increased by 1.6% from baseline; however, the difference between treatment groups was estimated as 0.9% (non-significant). This study suggests the potential usefulness of AKG-Ca in osteopenic postmenopausal women. AKG-Ca induced beneficial changes in serum CTX, which was consistent with preserving the bone mass in the lumbar spine; however, the long-term effect needs to be further investigated.

Filip RS, Pierzynowski SG, Lindegard B, Wernerman J…
Int J Vitam Nutr Res Mar 2007
PMID: 17896582

AKG Reduces Gastrectomy-Evoked Bone Loss in Rats

Abstract

Dietary alpha-ketoglutarate reduces gastrectomy-evoked loss of calvaria and trabecular bone in female rats.

Surgical removal of the stomach (gastrectomy, Gx) leads to osteopenia in animals and in humans. In the rat, Gx adversely affects calvaria and trabecular bone. alpha-Ketoglutarate (AKG) is a precursor of hydroxyproline–the most abundant amino acid in bone collagen. The purpose of this study was to investigate the effects of dietary AKG on Gx-induced osteopenia.
Twenty female Sprague-Dawley rats were subjected to Gx and divided between two groups: Gx+AKG in the drinking water and Gx+Vehicle (i.e. drinking water without AKG). Another 20 rats were sham-operated and divided between two groups: Sham+AKG and Sham+Vehicle. The daily dose of AKG was 0.43 g per 100 g rat. All the rats were killed 8 weeks later and the calvariae, femora and tibiae were collected. The integrity of the calvariae was analysed planimetrically, following transillumination and photography. The bone mineral content (BMC) and bone mineral density (BMD) were measured in the right femorae and tibiae (bone densitometry), leaving the left femorae and tibiae to be analysed histomorphometrically (measurement of trabecular bone volume and trabecular fractal dimension).
Gx caused calvarial bone degradation, reduced trabecular bone (femur and tibia) and impaired trabecular architecture. In addition, Gx lowered the femoral/tibial BMC and BMD (mainly cortical bone). Dietary AKG counteracted the Gx-evoked impairment of calvaria and trabecular bone but failed to affect the BMC and the BMD in either sham- operated or Gx rats.
Gx resulted in loss of calvarial, trabecular and cortical bone in the rat. AKG counteracted the effect of Gx on calvaria and trabecular bone but not on cortical bone.

Dobrowolski PJ, Piersiak T, Surve VV, Kruszewska D…
Scand. J. Gastroenterol. 2008
PMID: 18415747

AKG Increases Bone Length and Estrogen in Pigs

Abstract

The long-term effect of alpha-ketoglutarate, given early in postnatal life, on both growth and various bone parameters in pigs.

The long-term effect of alpha-ketoglutarate (AKG) given for 21-24 days post-partum, on the skeleton of commercial pigs, was investigated. In experiment A, 12 pigs were given AKG [0.1 g/kg of body weight (b.w.) per day per os], while 12 controls were administered vehicle. At day 169, the left and right femur, humerus and sixth ribs were analysed for mechanical and geometrical properties and quantitative computed tomography. In experiment B, 32 piglets were divided equally into an AKG group (0.3 g/kg of b.w. per day) or a control group. Blood, taken at days 24 and 53 was analysed for plasma 17 beta-oestradiol. The main bone effect of AKG was to increase bone length in the sixth rib (7.3%, p < 0.01), ultimate strength (23%, p < 0.05), Young s modulus (52%, p < 0.001) and maximum elastic strength (31%, p = 0.056) compared with controls. In both experiments, AKG preferentially increased the growth of female piglets, whilst for male piglets AKG had the opposite effect. In addition, AKG elevated plasma 17 beta-oestradiol levels compared to those of controls at the end of the period of treatment (20%, p = 0.002). It is concluded that AKG has long-term effects on rib properties when given early in postnatal life whilst it elevates plasma 17 beta-oestradiol levels only so long as it is being administered.

Andersen NK, Tatara MR, Krupski W, Majcher P…
J Anim Physiol Anim Nutr (Berl) Oct 2008
PMID: 19012595

AKG Improves Bone Mineralization in Ovariectomized Rats

Abstract

Anti-osteopenic effect of alpha-ketoglutarate sodium salt in ovariectomized rats.

The purpose of the study was to determine the effect of alpha-ketoglutarate sodium salt (AKG) treatment on the mineralization of the tibia in female rats during the development of osteopenia (Experiment-1) and in the condition of established osteopenia (Experiment-2). Thirty-two female rats were ovariectomized (OVX) to induce osteopenia and osteoporosis and another 32 female rats were sham-operated (SHO) and then randomly divided between the two experiments. In Experiment-1, the treatment with AKG started after a 7-day period of convalescence, whereas in Experiment-2 the rats were subjected to a 60-day period of osteopenia fixation, after which the actual experimental protocol commenced. AKG was administered in the experimental solution for drinking at a concentration of 1.0 mol/l and a placebo (PLC) was used as a control solution. After 60 days of experimental treatment the rats in both experiements were sacrificed, the body weight recorded, and blood serum and isolated tibia were stored for further analysis. The bones were analyzed using tomography and densitometry, and for estimation of mechanical properties the 3-point bending test was used. Serum concentrations of osteocalcin and collagen type I crosslinked C-telopeptide were measured. The anabolic effects of AKG on bone during osteopenia development in Experiment-1 not only stopped the degradation of bone tissue, but also stimulated its mineralization. The usage of AKG in animals with established osteopenia (Experiment-2) was not able to prevent bone atrophy, but markedly reduced its intensity. The stimulation of tibia mineralization after AKG treatment has been also argued in healthy SHO animals. The results obtained prove the effectiveness of AKG usage in the prophylaxis and therapy of osteopenia and osteoporosis, induced by bilateral gonadectomy. Additionally, the results clearly prove that treatment with AKG improves the mineralization of bone tissue in healthy animals.

Radzki RP, Bienko M, Pierzynowski SG
J. Bone Miner. Metab. Nov 2012
PMID: 22864414

AKG Improves Bone in Turkeys

Abstract

Effects of alpha-ketoglutarate on bone homeostasis and plasma amino acids in turkeys.

The objective of the study was to evaluate the effect of denervation and alpha-ketoglutarate (AKG) administration on the development of osteopenia in the turkey radius. At 22 d of age, all turkeys were subjected to neurectomy of the right radius. Control turkeys were given a saline solution into the crop each day for 97 d. Experimental turkeys were given 0.4 g of AKG/kg of BW into the crop each day. After 98 d, BW was not affected by the AKG treatment. Volumetric bone mineral density of the radius was measured by quantitative computed tomography. Mechanical properties were tested using a 3-point bending test. Cross-sectional area, second moment of inertia, and mean relative wall thickness were measured as well. Amino acid concentrations were assessed with the use of ion-exchange chromatography. Denervation had a negative effect on all bone characteristics that were measured except bone length. The AKG had a positive effect on all bone characteristics except bone length. Plasma concentrations of proline and leucine were increased by AKG, whereas concentrations of taurine and glutamine were decreased. The turkey radius appears to be a good model for studying osteopenia because its development can be affected by treatments such as denervation and AKG administration.

Tatara MR, Brodzki A, Krupski W, Sliwa E…
Poult. Sci. Oct 2005
PMID: 16335130

AKG Anabolic on Bone in Turkeys

Abstract

The influence of alpha-ketoglutarate (AKG) on mineralisation, mechanical and structural properties of ulna in turkey under conditions of osteotomy and denervation.

Background: Mechanical endurance of bones to acting forces is a result of geometrical properties, mineralisation and quality of the material they are built. Bone mineral density decrease influences lower bone mechanical endurance and its higher susceptibility on fractures. Among many factors that condition proper growth, development and repair processes of skeletal system, nervous system plays very important role in processes of bone metabolism regulation and its homeostasis maintenance. Bone fractures occurrence as a result of osteopenia and its fractures connected with peripheral nervous system injury require investigations of new and effective treatments that would guarantee correct repair processes of bone tissue and its physiological function maintenance.
Material and methods: All investigation was performed on 16 turkeys divided into two groups. Right ulnae were subjected to denervation, osteotomy and osteosynthesis. The first group of turkeys served as control, the second group were administered alpha-ketoglutarate (AKG) directly to crop at the dosage of 0.4g/kg b.w./day by 14 weeks, starting on the next day after surgery. After finishing breeding part of experiment, the influence of AKG on mineralisation, structural and mechanical properties of denervated and osteotomied ulna was investigated.
Results: Performed investigations on ulna after its osteotomy and denervation elucidated different callus formation in turkeys belong to control group and receiving AKG. The positive influence of alpha-ketoglutarate administration on morphology, mineralisation and mechanical properties of experimentally osteotomied and denervated ulna was stated.
Conclusions: Obtained results prove anabolic effect of alpha-ketoglutarate on bone tissue, after its administration via digestive tract. Considering increased mineralisation, higher volumetric cortical bone density and increased trabecular bone density, AKG can be utilised as a factor in prevention of osteopenia and osteoporosis. Achieved results indicate possibility of existence connection by AKG between digestive system and skeletal system.

Tatara MR, Pierzynowski GS, Majcher P, Krupski W…
Ortop Traumatol Rehabil Oct 2003
PMID: 17679850

Palm Leaf Enhances Bone in Ovariectomized Rats

Abstract

Catechin-rich oil palm leaf extract enhances bone calcium content of estrogen-deficient rats.

Postmenopausal estrogen deficiency often causes bone density loss and osteoporosis. This study evaluated the effects of an oral administration of oil palm leaf extract (OPL) on bone calcium content and structure, bone density, ash weights, and serum total alkaline phosphatase (T-ALP) of estrogen-deficient ovariectomized (OVX) rats.
Female Sprague-Dawley rats were divided into five experimental groups: 1) intact (normal control); 2) ovariectomized (OVX control), and OVX rats supplemented with 3) 2% (w/v) green tea (OVX + GT), 4) OPL 150 mg/kg of body weight, or 5) OPL 300 mg/kg of body weight in the drinking water.
After 3 mo, the OVX control rats had significantly decreased femur and tibia masses (-5% and -3%, respectively), ash (-15% and -10%), calcium content (-0.5% and -2.7%), and bone density and T-ALP concentrations (-40%) compared with intact rats. The catechin-rich OPL dose dependently increased the OVX bone density and structure, femur and tibia masses (by +8% and +12% respectively), ash (by +30% and +20% respectively), calcium (by +3% and +5%), and T-ALP concentrations (by +76%) compared with the OVX rats. The increases by OPL were higher than that in OVX + GT and control intact rats.
The catechin-rich OPL increased the bone mass in estrogen-deficient rats by increasing osteoblast activities to higher levels than in normal rats and those supplemented with GT. This was shown by the modulation of serum T-ALP levels, bone calcium content, total mineral content, and bone histologic structure. The OPL is a potential inexpensive ingredient for protection against osteoporosis and influences bone metabolism by encouraging bone formation.

Bakhsh A, Mustapha NM, Mohamed S
Nutrition Apr 2013
PMID: 23290096