[Methylenetetrahydrofolate reductase polymorphism C677T in patients with consolidated fractures and pseudarthrosis of long bones: relationship with homocystein and inflammatory mediators]

In article described research the results of the prevalence of the genetic polymorphism of the gene Methylentetrahydrofolatereductase C677T (MTHFR) in 130 patients with pseudarthrosis of long bones and in those with consolidated fractures. The incidence of allele-T among patients with pseudarthrosis was 1.4 times higher than among those with consolidated fractures. Pathological genotype MTHFR 677-TT was associated with the development avital types of pseudarthrosis and increase the proportion of people with hyperhomocysteinemia, high content of inflammatory mediators and development refracture.

Plasma homocysteine, folate, and vitamin B 12 and the risk of hip fracture: the hordaland homocysteine study

Homocysteine and related factors were evaluated as risk factors for subsequent hip fractures among 4766 elderly men and women. High levels of homocysteine and low levels of folate predicted fracture, whereas vitamin B12 and genotypes were not related to fracture risk. High homocysteine may be a modifiable risk factor for hip fracture.

INTRODUCTION

Elevated plasma total homocysteine (tHcy) and deficiencies of folate and vitamin B12 are associated with risk of osteoporosis and fracture. We examined whether plasma levels of tHcy, folate, and vitamin B12 and the methylenetetrahydrofolate reductase (MTHFR) 677C-->T and 1298C-->T polymorphisms predicted hip fracture.

MATERIALS AND METHODS

This was a population-based prospective study of 2639 women and 2127 men who were 65-67 yr at enrollment in 1992-1993. Information on hip fracture was obtained from computerized records of discharge diagnoses from all hospitalizations in the region in the period between enrollment and November 30, 2005. Cox proportional hazard regression was used to estimate fracture risk according to levels of plasma tHcy, folate, and vitamin B12 and for different genotypes.

RESULTS

Over a median follow-up period of 12.6 yr, hip fracture was recorded in 184 (7.0%) women and 90 (4.2%) men. The adjusted hazard ratio (95% CI) for fracture in subjects with high (>or=15 microM) compared with low levels (<9.0 microM) of tHcy was 2.42 (1.43-4.09) among women and 1.37 (0.63-2.98) among men. Dose-response analyses indicated a positive association between plasma tHcy and risk of fracture in both sexes and a negative association between plasma folate and risk of fracture among women only. Plasma vitamin B12 level or MTHFR genotype was not significantly related to risk of fracture after adjustments for confounding factors. The association between tHcy and risk of hip fracture was only slightly weakened by adjustments for plasma levels of vitamin B12 and folate.

CONCLUSIONS

tHcy seems to be a predictor for hip fracture among elderly men and women. Folate was a predictor among women only, whereas vitamin B12 and MTHFR genotype did not predict hip fracture. Our data corroborate the hypothesis that homocysteine may play a role in the pathogenesis of osteoporotic fractures.

Increased collagen degradation around loosened total hip replacement implants

OBJECTIVE

To assess collagen degradation and its relationship to some of the key collagenolytic proteinases in the aggressive synovial membrane-like interface tissue around aseptically loosened hip replacement implants.

METHODS

The medical indication for the primary total hip replacement was osteoarthritis in all study patients. Samples from the study patients were compared with control synovial membranes obtained from trauma (hip fracture) patients. Proteoglycans were extracted with 4M guanidinium chloride. Denatured collagen in the remaining matrix was solubilized with alpha-chymotrypsin. Nonsoluble matrix and supernatant fractions were acid hydrolyzed before measurement of hydroxyproline. The proportion of soluble (in vivo-degraded) collagen of the total sample collagen content was calculated. Proteinases were stained using the avidin-biotin-peroxidase complex method.

RESULTS

Collagen in the interface membrane from the implants was highly degraded (mean +/- SEM 20 +/- 3%) compared with that in the control synovial membranes (12 +/- 1%; P = 0.007). In controls, the degree of collagen degradation did not correlate with levels of matrix metalloproteinase 1 (MMP-1), MMP-13, or cathepsin K, although MMP-1 approached statistical significance. In interface membranes, the correlations were r = 0.88 (P = 0.002), r = 0.92 (P = 0.001), and r = 0.98 (P < 0.0001) for MMP-1, MMP-13, and cathepsin K, respectively.

CONCLUSION

In normal synovial membrane, collagen matrix remodeling may be mainly an intracellular process. In contrast, pathologic tissue destruction in the interface membrane from prosthetic hip joints is associated with a shift toward MMP-13 and cathepsin K, which become activated and overcome their endogenous inhibitors (tissue inhibitors of metalloproteinases and cystatin C). The highly significant correlation between collagen degradation and cathepsin K indicates an extracellular role of this acidic endoproteinase, consistent with previous observations concerning the acidity of the interface membrane.

Association of a common allelic polymorphism (C677T) in the methylene tetrahydrofolate reductase gene with a reduced risk of osteoporotic fractures. A case control study in Danish postmenopausal women

Twin studies indicate a substantial genetic component in the development of osteoporosis. One of the latest studied candidate genes is the one coding for methylene tetrahydrofolate reductase (MTHFR) (C677T) in which a point mutation gives rise to a thermolabile variant of MTHFR. The aim of this study was to investigate the influence of this mutation on peripheral measures of bone density and on the odds ratios (OR) for hip and lower forearm fracture in a case control study of Danish postmenopausal women. A total of 74 women with lower forearm fracture, 41 women with hip fracture, and 207 age-matched controls were included. All had broadband ultrasound attenuation (BUA) and speed of sound (SOS) measured at the heel as well as bone mineral density (BMD) measured by dual X-ray absorptiometry at the distal forearm. The MTHFR (C677T) genotypes were determined using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). Only 2 of 21 individuals with the TT genotype had sustained a fracture as opposed to 46 of 142 with the CT genotype and 67 of 159 with the CC genotype (P = 0.007). Using logistic regression, the following odds ratios were found when comparing the individuals homozygotic for the C-allele with those homozygotic for the T-allele: lower forearm fracture OR = 3.93 (1.25; 12.40, P = 0.02), hip fracture OR = 6.99 (l.35; 36.92, P = 0.02) and the fractures combined OR = 4.33 (1.73; 10.81, P = 0.002). In this study, the MTHFR (C677T) genotypes were not significantly associated with BMD at the lower forearm or with ultrasound parameters measured at the calcaneus. However, a significant increase in the odds ratio of fracture was found for the wild-type C-allele.

Comparison of bone and total alkaline phosphatase activity on bone turnover during menopause and in patients with established osteoporosis

OBJECTIVE

Recently, a bone alkaline phosphatase (AP) enzyme immunoassay (EIA) was developed for measurement of bone AP activity with a monoclonal antibody. We compared the clinical performance of bone AP (bAP) measured by EIA and total AP (tAP) to examine if bAP is preferable to tAP as a bone formation marker in the post-menopause and established osteoporosis.

DESIGN AND PATIENTS

Serum was obtained from 50 pre- and 93 post-menopausal healthy women, and 54 osteoporotic patients with vertebral fractures and 57 patients with hip fracture.

MEASUREMENTS

Total AP was measured spectrophotometrically with p-nitrophenyl phosphate as substrate. The intra- and inter-assay coefficients of variation were 0.7-1.8% and 0.6-1.1%, respectively. Bone AP activity (bAP) was measured by EIA kit, ALKPHASE-B (Metra Biosystems, Inc.) using a monoclonal antibody against human bone AP. The intra- and inter-assay CVs were 4.0-8.3% and 6.2-7.9%, respectively.

RESULTS

The percentage mean increase of bAP (54.9%) in post-menopausal subjects over premenopausal subjects was higher than that of tAP (40.1%). In age-matched comparison, % mean increases were 57.5% for bAP and 35.3% for tAP. Z-score for bAP in post-menopausal subjects was significantly higher than that for tAP. However, there was no significant difference in Z-scores between tAP and bAP in osteoporotic patients with vertebral fractures or with hip fracture. The correlation coefficient of bAP with age (r = 0.316) was similar to that of tAP with age (r = 0.319). In post-menopausal subjects, there was no difference in the concentrations of tAP nor bAP among the groups in whom times since the menopause was 0-9 years, 10-19 years and more than 20 years. Bone AP was highly correlated to tAP in the normal subjects, the patients and the total study group.

CONCLUSION

Preference can be given to bone AP by enzymatic immunoassay over total AP based on their clinical utility during the menopause; however, no preference can be given to bone AP over total AP in established osteoporosis.

Perioperative creatine phosphokinase trends in elderly patients with hip fracture

A prospective study of the serum levels of unfractionated creatine phosphokinase (CPK) in 69 consecutive elderly patients undergoing surgery for hip fracture is reported. Serum unfractionated CPK levels were measured on admission, on the evening following surgery and daily for the first five days post-operatively. All of the CPK levels measured on admission were within the normal range for this laboratory. A gradual rise in CPK levels followed surgery. On the evening following surgery 75% of values were greater than the upper limit of the normal reference range. The peak values were seen on day 1 post-operatively but 25% of values were still less than the reference maximum. A gradual decline was seen after this and at day 5 post operatively 50% of values were within the normal reference range. A single unfractionated CPK determination is not of diagnostic benefit in the post-operative period in elderly patients with hip fracture. However, patients with intracapsular and intertrochanteric fractures do not show elevation of unfractionated CPK levels prior to surgery.

Operative treatment of acute hip fractures: its effect on serum creatine kinase, lactate dehydrogenase and their isoenzymes

Serum creatine kinase, lactate dehydrogenase, and their isoenzymes were prospectively studied in 16 patients who underwent operative treatment of acute hip fractures. No perioperative myocardial infarctions occurred; however, two patients died of noncardiac causes. We found that skeletal muscle injury associated with operative treatment of acute hip fractures did not result in significant elevations of serum CK-MB or the LD-1/LD-2 ratio. CK-MB activity exceeding 5% of total CK activity was observed in five patients who did not experience acute perioperative myocardial infarction; however, no patient had an absolute CK-MB value exceeding 50 IU/L. Elevations of serum CK-MB exceeding 50 IU/L and a LD-1/LD-2 ratio exceeding 1.0, therefore, should not be attributed to skeletal muscle injury alone following the operative treatment of acute hip fractures.

Vitamin D concentrations in women of postmenopausal age with fractures of the femoral neck

Thirty-eight women of postmenopausal age, suffering from fractures of the femoral neck or vertebral bodies were studied in relation to differences in bone metabolism. The blood and urinary changes concerned in mineral and bone metabolism were recorded within 10 days of trauma, and in some femoral neck fractures, a histological study of the femoral heads removed in the course of prosthetic substitution was carried out. The patients with femoral neck fractures were older than those with vertebral fractures and had metabolic and histological findings suggestive of osteomalacia. A particularly significant difference between the two groups was the plasma level of 25 hydroxycholecalciferol, which was lower in femoral neck fractures, and the urinary excretion of calcium, which was also more reduced in femoral neck fractures. A deficit of vitamin D hepatic metabolite thus appears to be a risk factor for femoral neck fractures in old patients.

Changes in serum alkaline phosphatase after femoral fractures

Osteomalacia may be a contributory factor in some patients in the development of fractures of the femoral neck and complicate the subsequent management. The level of serum alkaline phosphatase is often valuable in the diagnosis of metabolic bone disease but rises after any uncomplicated fracture, and since such a rise may limit the diagnostic usefulness of this measurement in detecting osteomalacia its extent was assessed in 106 patients. In the majority serum levels were normal on admission, rising after seven to nine days to reach a maximum within a month after fracture. Elevated levels on admission were found in patients with osteomalacia, liver damage or where there had been a delay of several weeks between injury and admission. In a small number of patients normal levels on admission subsequently reached very high values, usually in association with comminution or instability of the fracture. Elevated levels persisted for six to twelve weeks after fracture, the major influence upon the level at this time being the maximum value achieved rather than the presence of osteomalacia. If patients are to be screened for osteomalacia, the alkaline phosphatase must be measured within the first week after a fracture to avoid the distorting influences of the fracture itself.