共查询到20条相似文献,搜索用时 562 毫秒
1.
P. Schneider C. Reiners G. R. Cointry R. F. Capozza J. L. Ferretti 《Osteoporosis international》2001,12(8):639-646
The aim of this study was to test the ability of some indicators of different aspects of bone quality (assessed by peripheral
quantitative computed tomography in the distal radius) to discriminate between fractured and nonfractured individuals. The
study compared 214 women aged 45–85 years, free of any bone-affecting treatment, of whom 107 had suffered a Colles” fracture
in the previous 6 months and 107 did not. The determinations included bone tissue or mineral “mass” indicators (trabecular,
cortical and total volumetric mineral content, cortical bone area); bone “density” estimates (trabecular, cortical and total
volumetric mineral density), and the Cartesian (rectangular) and polar moments of inertia as influences of cross-sectional
architecture on resistance to bending and torsional loads, respectively.
The influences of body height, weight and age on the tomographic indicators were minimized by adjusting the data according
to the partial coefficients of multiple stepwise regressions. The adjusted values of all the indicators were lower in fractured
than in nonfractured groups. The prevalence of fractures was directly related to the actual values of the indicators, rather
than the age or body habitus of the individuals. The significance of these differences between the assessed indicators decreased
in the following order: trabecular “mass” > trabecular “density” > cortical or total “mass” > cortical architecture > total
or cortical “density” indicators. Within the same type of bone, the tissue or mineral “mass” indicators performed better than
the “density” indicators. The cortical bone density did not give useful information, probably because of technical difficulties.
Odds-ratios and receiver-operating characteristic (ROC) analyses confirmed those features. The selected “cut-off” values of
the indicators as determined by the ROC curves (very close to those determined by the inflexion points of the logistic reression
curves) may indicate reference limits to detect persons at risk of fracture according to the type of information provided
by each variable. These results show that these tomographic indicators discriminate well between fractured and nonfractured
individuals, and should be suitable to assess how total, cortical and trabecular bone strength in the distal radius could
affect different kinds of strength regardless of the age or body habitus of the individual. Their ability to estimate fracture
risk from different biomechanical points of view should be assessed by adequately designed, prospective studies.
Received: June 2000 / Accepted: January 2001 相似文献
2.
Harold M. Frost 《Journal of bone and mineral metabolism》1997,15(3):115-121
In growing subjects, the mechanical loads on bones keep increasing. Meanwhile biologic activities try to adapt bone strength
to those increasing loads, but the adaptations lag behind the need. They can only “catch up” when increases in body weight,
muscle strength, and bone length plateau in adult life. The lag during growth causes a deficit of bone strength relative to
the needs of muscle strength and body weight, especially in cortical bone. Acceleration of that growth during the adolescent
growth spurt would further increase that bone strength deficit, which should do two things: (1) It should increase fractures
from falls and related injuries during the growth spurt, which happens; and (2) it should decrease similar fractures in young
adults when the adaptations in bone strength finally “catch up” to the need. This decrease also occurs. 相似文献
3.
Frost HM 《Journal of bone and mineral metabolism》2002,20(6):319-325
Recent articles by Drs. Lanyon, Raisz, Seeman, and Skerry summarized some emerging views about the causes and nature of some
effects of mechanical loading on bones and “osteoporosis”, the causes of fractures in that condition, and the causes of increased
bone fragility and age-related bone loss. This article would supplement theirs with further evidence and ideas. This includes
a definition of bone health that suggests currently popular classifications of “osteoporosis” and “osteopenia” could fail
to distinguish healthy differences from normal averages from true bone diseases. This definition also suggests a classification
of osteoporotic fractures that could question some current methods and uses of noninvasive absorptiometry. This article emphasizes
concepts and generalities, and leaves resolution of any devils in the details to other places, times, and people.
Received: March 29, 2002 / Accepted: May 28, 2002
Offprint requests to: H.M. Frost 相似文献
4.
《BONE》2013,56(2):335-346
Bone loss occurs during adulthood in both women and men and affects trabecular bone more than cortical bone. The mechanism responsible for trabecular bone loss during adulthood remains unexplained, but may be due at least in part to a reduced mechanoresponsiveness. We hypothesized that trabecular and cortical bone would respond anabolically to loading and that the bone response to mechanical loading would be reduced and the onset delayed in adult compared to postpubescent mice. We evaluated the longitudinal adaptive response of trabecular and cortical bone in postpubescent, young (10 week old) and adult (26 week old) female C57Bl/6J mice to axial tibial compression using in vivo microCT (days 0, 5, 10, and 15) and dynamic histomorphometry (day 15). Loading elicited an anabolic response in both trabecular and cortical bone in young and adult mice. As hypothesized, trabecular bone in adult mice exhibited a reduced and delayed response to loading compared to the young mice, apparent in trabecular bone volume fraction and architecture after 10 days. No difference in mechanoresponsiveness of the cortical bone was observed between young and adult mice. Finite element analysis showed that load-induced strain was reduced with age. Our results suggest that trabecular bone loss that occurs in adulthood may in part be due to a reduced mechanoresponsiveness in this tissue and/or a reduction in the induced tissue deformation which occurs during habitual loading. Therapeutic approaches that address the mechanoresponsiveness of the bone tissue may be a promising and alternate strategy to maintain trabecular bone mass during aging. 相似文献
5.
Maureen E. McAteer Paul J. Niziolek Shana N. Ellis Daniel L. Alge Alexander G. Robling 《Calcified tissue international》2010,86(5):389-396
Mechanical loading and intermittent parathyroid (iPTH) treatment are both osteoanabolic stimuli and are regulated by partially
overlapping cellular signaling pathways. iPTH has been shown clinically to be effective in increasing bone mass and reducing
fracture risk. Likewise, mechanical stimulation can significantly enhance bone apposition and prevent bone loss, but its clinical
effects on fracture susceptibility are less certain. Many of the osteogenic effects of iPTH are localized to biomechanically
suboptimal bone surfaces, whereas mechanical loading directs new bone formation to high-stress areas and not to strain-neutral
areas. These differences in localization in new tissue, resulting from load-induced versus iPTH-induced bone accumulation,
should affect the relation between bone mass and bone strength, or “tissue economy.” We investigated the changes in bone mass
and strength induced by 6 weeks of mechanical loading and compared them to changes induced by 6 weeks of iPTH treatment. Loading
and iPTH both increased ulnar bone accrual, as measured by bone mineral density and content, and fluorochrome-derived bone
formation. iPTH induced a significantly greater increase in bone mass than loading, but ulnar bone strength was increased
approximately the same amount by both treatments. Mechanical loading during growth can spatially optimize new bone formation
to improve structural integrity with a minimal increase in mass, thereby increasing tissue economy, i.e., the amount of strength
returned per unit bone mass added. Furthermore, exercise studies in which only small changes in bone mass are detected might
be more beneficial to bone health and fracture resistance than has commonly been presumed. 相似文献
6.
S. R. Kummari A. J. Davis L. A. Vega N. Ahn E. H. Cassinelli C. J. Hernandez 《Calcified tissue international》2009,85(2):127-133
Microscopic tissue damage has been observed in otherwise healthy cancellous bone in humans and is believed to contribute to
bone fragility and increased fracture risk. Animal models to study microscopic tissue damage and repair in cancellous bone
would be useful, but it is currently not clear how loads applied to a whole animal bone are related to the amount and type
of resulting microdamage in cancellous bone. In the current study we determine the relationship between applied cyclic compressive
overloading and the resulting amount of microdamage in isolated rat tail vertebrae, a bone that has been used previously for
in vivo loading experiments. Rat caudal vertebrae (C7–C9, n = 22) were potted in bone cement and subjected to cyclic compressive loading from 0 to 260 N. Loading was terminated in the
secondary and tertiary phases of the creep-fatigue curve using custom data-monitoring software. In cancellous bone, trabecular
microfracture was the primary form of microdamage observed with few microcracks. Trabecular microfracture prevalence increased
with the amount of cyclic loading and occurred in nine out of 10 specimens loaded into the tertiary phase. Only small amounts
of microdamage were observed in the cortical shell of the vertebrae, demonstrating that, under axial cyclic loading, damage
occurs primarily in regions of cancellous bone before overt fracture of the bone (macroscopic cracks in the cortical shell).
These experiments in isolated rat tail vertebrae suggest that it may be possible to use an animal model to study the generation
and repair of microscopic tissue damage in cancellous bone. 相似文献
7.
Morphological evidence of gap junctions between bone cells 总被引:9,自引:0,他引:9
Stephen B. Doty 《Calcified tissue international》1981,33(1):509-512
Summary Cell membrane specializations occur at contact sites between adjacent osteoblasts and osteoblasts and osteocytes. These junctions
have been described by other investigators as being important in preventing the extracellular movement of material around
bone cells. Previously we described how certain small proteins circumvented the osteoblast population and rapidly penetrated
the canalicular-osteocyte system. In the present study we used lanthanum colloid as an extracellular marker; the lanthanum
readily penetrated the bone cell junctions and the extracellular space of bone. Morphologically, these junctions were not
“tight” or “occluding” structures, but resembled “gap” junctions. These gap junctions contained elements which formed intercellular
bridges between adjacent cells but also maintained a 2 nm space between cells that contained extracellular fluid. These gap
junctions may have an important function in the control or coordination of bone cell activity throughout a given volume of
bone. 相似文献
8.
Misof BM Bodingbauer M Roschger P Wekerle T Pakrah B Haas M Kainz A Oberbauer R Mühlbacher F Klaushofer K 《Calcified tissue international》2008,83(3):167-175
Patients with “hepatic” bone disease exhibit increased fracture incidence. The effects on bone material properties, their
changes due to orthotopic liver transplantation (OLT), as well as zolendronate (ZOL) treatment have not yet been investigated.
We studied bone mineralization density distribution (BMDD) in paired transiliacal biopsies (at and 6 months after OLT) from
patients (control CON n = 18, treatment group ZOL n = 21, the latter treated with i.v. ZOL at doses of 4 mg/month) for how bone at the material level was affected by the “hepatic”
disease in general, as well as by OLT and ZOL in particular. (1) BMDD parameters at baseline reflected disturbed bone matrix
mineralization in “hepatic” bone disease combined with low turnover. Trabecular bone displayed a decrease in mean and most
frequent calcium concentration (CaMEAN −2.9% and CaPEAK −2.8%, respectively; both P < 0.001), increased heterogeneity of mineralization (CaWIDTH +12.2%, P = 0.01), and increased percentage of bone areas with low mineralization (CaLOW +32.4%, P = 0.02) compared to normal; however, there were no differences compared to cortical bone. (2) Six months after OLT, ZOL-treated
trabecular bone displayed reduced CaLOW (−32.0%, P = 0.047), cortical bone increased CaMEAN (+4.2%, P = 0.009), increased CaPEAK (+3.3%, P = 0.040), and decreased CaLOW (−55.7, P = 0.038) compared to CON and increased CaMEAN compared to baseline (+1.9, P = 0.032) without any signs of hyper- or defective mineralization. These changes as consequence of the antiresorptive action
of ZOL visible already after 6 months result in beneficial effects on bone matrix mineralization, likely contributing to the
significant decrease in fracture incidence observed in these patients 2 years post transplantation.
B. M. Misof and M. Bodingbauer contributed equally. 相似文献
9.
Glenn K. Wakley Brad L. Baum Kathleen S. Hannon Russell T. Turner 《Calcified tissue international》1988,43(6):383-388
Summary The effects of a 3-week treatment with the nonsteroidal “antiestrogen” tamoxifen were determined on cortical and trabecular
bone mass of the tibiae of growing male rats that had undergone unilateral sciatic neurotomy (USN). USN resulted in decreases
in cortical area (−11.3%), cross-sectional area (−8.4%), and periosteal bone formation rate (−32.6%) in cortical bone, indicating
that the disuse osteopenia results in a decrease in bone formation in cortical bone. USN significantly reduced the amount
of trabecular bone in our metaphyseal sampling site (−75%), markedly increasing the amount of bone surface lined by osteoclasts
(+65%) without affecting the surface lined by osteoblasts. These results suggest that trabecular bone disuse osteopenia is
due, at least in part, to increased bone resorption. Tamoxifen treatment significantly reduced the loss of trabecular bone,
restoring resorbing surface length to the control (sham-operated) animal levels. Tamoxifen treatment of sham-operated animals
increased trabecular bone area and surface by 35.7% (±10.5) and 41.8% (±7.8), respectively, and reduced resorbing surface
by 21.5% (±11.6) compared with sham-operated placebo-treated rats. Tamoxifen had no significant effect on cortical bone parameters
in the sham-operated group. The results indicate that tamoxifen is able to reduce the trabecular bone loss that results from
USN, but has no effect on cortical bone disuse osteopenia, or on trabecular bone formation. Moreover, tamoxifen treatment
of control (intact) animals inhibited the normal levels of bone resorption occurring in these rapidly growing animals. 相似文献
10.
Gabriel L Galea Lee B Meakin Dawn Savery Hanna Taipaleenmaki Peter Delisser Gary S Stein Andrew J Copp Andre J van Wijnen Lance E Lanyon Joanna S Price 《Journal of bone and mineral research》2015,30(3):423-435
Exposure of bone to dynamic strain increases the rate of division of osteoblasts and also influences the directional organization of the cellular and molecular structure of the bone tissue that they produce. Here, we report that brief exposure to dynamic substrate strain (sufficient to rapidly stimulate cell division) influences the orientation of osteoblastic cell division. The initial proliferative response to strain involves canonical Wnt signaling and can be blocked by sclerostin. However, the strain‐related orientation of cell division is independently influenced through the noncanonical Wnt/planar cell polarity (PCP) pathway. Blockade of Rho‐associated coiled kinase (ROCK), a component of the PCP pathway, prevents strain‐related orientation of division in osteoblast‐like Saos‐2 cells. Heterozygous loop‐tail mutation of the core PCP component van Gogh‐like 2 (Vangl2) in mouse osteoblasts impairs the orientation of division in response to strain. Examination of bones from Vangl2 loop‐tail heterozygous mice by µCT and scanning electron microscopy reveals altered bone architecture and disorganized bone‐forming surfaces. Hence, in addition to the well‐accepted role of PCP involvement in response to developmental cues during skeletal morphogenesis, our data reveal that this pathway also acts postnatally, in parallel with canonical Wnt signaling, to transduce biomechanical cues into skeletal adaptive responses. The simultaneous and independent actions of these two pathways appear to influence both the rate and orientation of osteoblast division, thus fine‐tuning bone architecture to meet the structural demands of functional loading. © 2014 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research. 相似文献
11.
M. Visocchi L. Argiolas M. Meglio B. Cioni P. Dal Basso M. Rollo D. Cabezas 《Acta neurochirurgica》2001,143(2):177-185
Summary Background. Clinical and experimental data on cerebral blood flow (CBF) changes during spinal cord stimulation (SCS) were published since
1986. The aims of the present work are: 1. To find an experimental model of reliable, simple and in vivo monitoring of “early”
basilar artery spasm after subarachnoid haemorrhage (SAH) and 2. To investigate the effects of cervical spinal cord stimulation
(CSCS) on it. Vasospasm due to SAH is both “acute” and “recurrent”. Early spasm occurs within minutes of the SAH, its duration
is approximately 1 hour. The need of different morphological and haemodynamic methods to evaluate experimental early spasm
is reported. To overcome intracranial surgical manipulations and biological effects of contrast and fixation media we designed
a model that allows “ in vivo” functional monitoring of basilar blood flow far away from the spasm without direct surgical
and chemical interference. Subsequently we investigated the effects of CSCS on the new model of “functional monitoring” of
the “early” cerebral vasospasm.
Method. 29 adult Burgundy rabbits were studied. Group 1: under homeostatic monitoring, “on-line” carotid blood flow (carotid BF) changes produced by SAH in cisterna magna of 12
(plus 5 sham treated) animals were studied from the common carotid artery after external carotid artery occlusion before,
during SAH and up to the end of the experiments. All the animals underwent digital subtraction cerebral panangiography (CPA)
after SAH obtaining a significant increase of carotid BF only when basilar vasospasm was shown by CPA. Carotid BF increase
during basilar vasospasm was defined “functional monitoring” of early spasm. Group 2: Twelve animals wearing a cervical epidural electrode underwent carotid BF “functional monitoring” of early basilar spasm
before and during CSCS.
Findings. Carotid BF changes during CSCS occurred in 10 animals. No carotid BF changes (i.e. no basilar vasospasm) occurred after SAH
up to the end of the experiments in all the stimulated animals.
Interpretation. CSCS is able to prevent “early spasm” due to SAH in all the animals studied with the new model of “functional monitoring”
described, independently from the occurrence and the sign for stimulation-induced carotid BF variations. The role and the
limits of reversible functional sympathectomy in mediating the effect of CSCS on early vasospam are discussed. 相似文献
12.
Background The prevalence of overweight and obesity is increasing dramatically worldwide. As a consequence, bariatric surgery for morbid
obesity is in constant development. Although bariatric surgery has proven its efficiency at achieving weight loss and correcting
comorbidities, it may cause vitamin deficiencies and subsequent complications. The goal of this review is to assess the impact
of obesity surgery on bone metabolism and to analyze the underlying mechanisms and relationships with adipokines. Our review
focuses on gastric banding, vertical banded gastroplasty, and gastric bypass.
Methods The articles were located via PubMed database, using the key words “bariatric surgery,” “weight loss,” “bone loss,” and “bone
metabolism” and published until May 2006.
Results Five main studies were reviewed concerning gastric banding and six concerning Roux-en-Y gastric bypass. An early increase
in bone markers (formation and resorption) is constantly found, prevailing on bone resorption, and resulting in early bone
loss.
Conclusion According to the few studies available, bone loss frequently occurs after bariatric surgery and particularly in a more pronounced
way after gastric bypass, but its clinical significance is still under discussion. In addition, the physiopathology of these
changes remains unclear, but could implicate adipokines such as leptin and adiponectin. 相似文献
13.
The load-carrying capacity of the skeleton is achieved and maintained as the result of a continued functional stimulus to the cell populations responsible for bone remodeling. Although some bone cells have been assumed to be influenced by the load-induced changes in strain throughout the matrix, no evidence is available to indicate which cells are susceptible to such strain change or how such transient events provide a sustained influence on cell behaviour. In the present study, we showed that a short period of dynamic loading in vivo affects the orientation of proteoglycan within bone tissue. This reorientation declines only slowly, thus providing a persistent record of the tissue's recent strain history. Such a record has the ability not only to "capture" strain transients but also to "update" and "average" them. In this way, the bone cells could be presented with a sustained and coherent stimulus directly related to dynamic strain transients. These transients are the tissue's principal function variable. 相似文献
14.
Y Takano C H Turner I Owan R B Martin S T Lau M R Forwood D B Burr 《Journal of orthopaedic research》1999,17(1):59-66
There is evidence that the collagen microarchitecture of bone is influenced by mechanical stresses or strains. We hypothesized that peak functional strains correlate with the elastic anisotropy and collagen orientation of bone tissue and that the bone anisotropy might be changed by altering the strain patterns in canine radii for 12 months. We tested these hypotheses in studies using nine adult foxhounds. The baseline group (n = 3) had three rosette strain gauges placed around the midshaft of the radius, and strain distributions were measured during walking. The osteotomy group (n = 3) had 2 cm of the ulna surgically removed, and the sham group (n = 3) received a sham osteotomy. The osteotomy and sham groups were allowed free movement in cages with runs for 12 months, after which strain distributions were measured on the radii during walking. Bone-tissue anisotropy and collagen architecture were measured in radii from which the in vivo longitudinal strain patterns had been measured. The collagen birefringence patterns were measured with use of a circularly polarized light technique, and the elastic anisotropy of the bone, mineral, and collagen matrix was evaluated with a novel acoustic microscopy technique. Peak longitudinal strains in the radius correlated with the normalized longitudinal structure index (a polarized light measure of collagen birefringence) and the tissue anisotropy ratio. The average anisotropy ratio was 1.28+/-0.01 in the posterior (compressive) cortex and 1.43+/-0.01 in the anterior (tensile) cortex (these values are significantly different at p < 0.0001). The ulnar osteotomy changed the strain pattern on the radius, causing increased tensile strains in the medial cortex by more than 5-fold that were associated with a significant increase in the anisotropy ratio in the bone tissue. The longitudinal structure index was strongly correlated (r = 0.62, p < 0.005) with the anisotropy ratio of demineralized bone but was not correlated with that of deproteinized bone; this indicates that it reflects collagen fibril orientation in the bone matrix. These results indicate that mechanical strains affect both collagen and mineral microarchitecture in bone tissue, i.e., tensile strains are associated with increased tissue anisotropy and compressive strains, with decreased anisotropy. 相似文献
15.
The role of serum concentrations of sex steroids and bone turnover in the development and occurrence of postmenopausal osteoporosis 总被引:2,自引:0,他引:2
Bente Juel Riis Paul Rødbro Claus Christiansen M.D. 《Calcified tissue international》1986,38(6):318-322
Summary It has been debated whether postmenopausal osteoporosis is characterized by high or low bone turnover and whether circulating
levels of sex steroids contribute to the occurrence of osteoporotic fractures. We examined 154 70-year-old women with or without
osteoporotic fractures, and 178 early postmenopausal women with a “rapid” or a “slow” bone loss. In all participants, we determined
markers of bone formation (serum alkaline phosphatase (AP) and serum bone Gla protein (BGP)), markers of bone resorption (fasting
urinary calcium/creatinine (FU Ca/Cr) and hydroxyproline/creatinine (FU Hpr/Cr)), and serum estrone (E1), estradiol (E2), androstenedione (A), and fat mass. The 70-year-old womenwith osteoporotic fractures had significantly elevated AP (P<0.001), BGP (P<0.001), and FU Hpr/Cr (P<0.001) compared with the groupwithout fractures. In the group of early postmenopausal women, the “rapid” bone losers had significantly increased FU Hpr/Cr (P<0.001) and FU Ca/Cr (P<0.001). E1, E2, A, and the fat mass did not differ in the groups with and without osteoporotic fractures, whereas the “rapid” bone losers
had significantly lower E1 (P<0.05), E2 (P<0.05), and fat mass (P<0.01) than the ‘slow” bone losers. It is concluded that patients with manifest osteoporosis and early postmenopausal women
with a rapid bone loss have increased biochemical markers of bone turnover. Moreover, the present study demonstrates that
early postmenopausal women with an “excessive” bone loss have significantly decreased serum estrogens, whereas it is not possible
to detect low estrogens in women with osteoporotic fractures. 相似文献
16.
A quantitative study of iliac bone histopathology on 62 cases with itai-itai disease 总被引:2,自引:0,他引:2
Summary Sixty-two autopsy cases with “itai-itai” or “ouch-ouch” (in English) disease and 50 control subjects were examined by static
quantitative bone histopathology. Decalcified sections after cyanuric chloride treatment (Yoshiki's method) [5–7] were used.
The small observer variances of the decalcified sections guaranteed the accuracy and precision of this method. In the static
measurement analyses, significant increases in formation parameters and decreases in structural parameters were observed (P<0.05–0.000001), suggesting the presence of a marked osteoid accumulation accompanied by a bone mass reduction. Discriminant
analysis clearly separated the patients from the control subjects. Two-thirds of the patients showed an increase in resorption
surface prior to osteoid deposition and a decrease in osteoblast surface. Double tetracycline labeling in 4 patients showed
an impaired osteoid maturation and mineralization. An impaired osteoblastic function was suggested by the results of the static
and dynamic histomorphometry. The bone cadmium contents were measured in 46 patients by an atomic absorption spectrophotometer
and found to be increased significantly (P<0.01). In Aluminon (an ammonium salt of aurine tricarboxytic acid) staining, a clear, reddish line was located in an osteoid-bone
interface, suggesting a reaction of Aluminon with tissue aluminium and/or cadmium. These results suggested that an impairment
of osteoblastic function and mineralization occurred in itai-itai disease and that cadmium is a possible etiological factor. 相似文献
17.
Polytrauma—pathophysiology and management principles 总被引:9,自引:0,他引:9
F. Gebhard M. Huber-Lang 《Langenbeck's archives of surgery / Deutsche Gesellschaft fur Chirurgie》2008,393(6):825-831
Background Multiple injury results in a complex pathophysiological and immunological response. Depending on the individual injury pattern,
the time elapsed after injury, and the systemic “danger response”, the surgical treatment has to be modified.
Objectives This overview provides new insights in the pathophysiology of the early danger response after polytrauma and outlines the
main resulting consequences for surgical management.
Results First, synchronically to the clinical assessment, life-saving procedures need to be performed rapidly, such as control of
massive intra-thoracic or abdominal bleeding and decompression of the chest and brain, as standardized by advanced trauma
life support guidelines. During the second phase of “day-one-surgery” damage-control interventions such as debridement, decompression
and temporary fracture stabilization are needed to avoid an excessive molecular and cellular danger response. Trauma-adjusted
surgical techniques are crucial to limit the systemic response known to put remote organs at risk. In the “vulnerable phase”
when the patient’s defense is rather uncontrolled, only “second look” debridement to minimize a “second hit” is recommended.
After stabilization of the patient as indicated by improvement of tissue oxygenation, coagulation, and decreased inflammatory
mediators, “reconstructive surgery” can be applied.
Conclusion Individually adjusted surgical “damage control” and “immune control” are important interactive concepts in polytrauma management. 相似文献
18.
Summary Comparison of infrared spectroscopic images of sections from biopsies of placebo-treated post-menopausal women and women treated
for 3 years with 10 mg/day alendronate demonstrated significant increases in cortical bone mineral content, no alterations
in other spectroscopic markers of “bone quality,” but a decrease in tissue heterogeneity.
Methods The material properties of thick sections from iliac crest biopsies of seven alendronate-treated women were compared to those
from ten comparably aged post-menopausal women without bone disease, using infrared spectroscopic imaging at ∼7 μm spatial
resolution. Parameters evaluated were mineral/matrix ratio, crystallinity, carbonate/amide I ratio, and collagen maturity.
The line widths at half maximum of the pixel histograms for each parameter were used as measures of heterogeneity.
Results The mineral content (mineral/matrix ratio) in the cortical bone of the treated women’s biopsies was higher than that in the
untreated control women. Crystallinity, carbonate/protein, and collagen maturity indices were not significantly altered; however,
the pixel distribution was significantly narrowed for all cortical and trabecular parameters with the exception of collagen
maturity in the alendronate treatment group.
Conclusions The increases in mineral density and decreased fracture risk associated with bisphosphonate treatment may be counterbalanced
by a decrease in tissue heterogeneity, which could impair tissue mechanical properties. These consistent data suggest that
alendronate treatment, while increasing the bone mass, decreases the tissue heterogeneity. 相似文献
19.
Prediction of Osteoporotic Fractures by Bone Densitometry and COLIA1 Genotyping: A Prospective, Population-Based Study in Men and Women 总被引:9,自引:0,他引:9
F. E. A. McGuigan G. Armbrecht R. Smith D. Felsenberg D. M. Reid S. H. Ralston 《Osteoporosis international》2001,12(2):91-96
Osteoporosis is a common disease with a strong genetic component, characterized by reduced bone mineral density and increased
fracture risk. Although the genetic basis of osteoporosis is incompletely understood, previous studies have identified a polymorphism
affecting an Sp1 binding site in the COLIA1 gene that predicts bone mineral density and osteoporotic fractures in several populations. Here we investigated the role
of COLIA1 genotyping and bone densitometry in the prediction of osteoporotic fractures in a prospective, population-based study of
men (n= 156) and women (n= 185) who were followed up for a mean (± SEM) of 4.88 ± 0.03 years. There was no significant difference in bone density,
rate of bone loss, body weight, height, or years since menopause between the genotype groups but women with the “ss” genotype
were significantly older than the other genotype groups (p= 0.03). Thirty-nine individuals sustained 54 fractures during follow-up and these predominantly occurred in women (45 fractures
in 30 individuals). Fractures were significantly more common in females who carried the COLIA1“s” allele (p= 0.001), although there was no significant association between COLIA1 genotype and the occurrence of fractures in men. Logistic regression analysis showed that carriage of the COLIA1“s” allele was an independent predictor of fracture in women with an odds ratio (OR) [95% CI] of 2.59 [1.23–5.45], along with
spine bone mineral density (OR = 1.57 [1.04–2.37] per Z-score unit) and body weight (OR = 1.05 [1.01–1.10] per kilogram). Moreover, bone densitometry and COLIA1 genotyping interacted significantly to enhance fracture prediction in women (p= 0.01), such that the incidence of fractures was 45 times higher in those with low BMD who carried the “s” allele (24.3 fractures/100
patient-years) compared with those with high BMD who were “SS” homozygotes (0.54 fracture/100 patient-years). We conclude
that in our population, COLIA1 genotyping predicts fractures independently of bone mass and interacts with bone densitometry to help identify women who
are at high and low risk of sustaining osteoporotic fractures.
Received: 16 November 2000 / Accepted: 9 June 2000 相似文献
20.
Endochondral bone formation occurs through a series of developmentally regulated cellular stages, from initial formation
of cartilage tissue to calcified cartilage, resorption, and replacement by bone tissue. Nasal cartilage cells isolated by
enzymatic digestion from rat fetuses were seeded at a final density of 105 cell/cm2 and cultured in Dulbecco's modified Eagle medium (DMEM) supplemented with 10% fetal calf serum in the presence of ascorbic
acid and β-glycerophosphate. First, cells lost their phenotype but in this condition they rapidly reexpressed the chondrocyte
phenotype and were able to form calcified cartilaginous nodules with the morphological appearance of cartilage mineralization
that occurs in vivo during endochondral ossification. In this mineralizing chondrocyte culture system, we investigated, between day 3 and day
15, the pattern expression of types II and X collagen, proteoglycan core protein, characteristic markers of chondrocyte differentiation,
as well as alkaline phosphatase and osteocalcin associated with the mineralization process. Analysis of labeled collagen and
immunoblotting revealed type I collagen synthesis associated with the loss of chondrocyte phenotype at the beginning of the
culture. However, our culture conditions promoted extracellular matrix mineralization and cell differentiation towards the
hypertrophic phenotype. This differentiation process was characterized by the induction of type X collagen mRNA, alkaline
phosphatase, and diminished expression of type II collagen and core protein of large proteoglycan after an increase in their
mRNA levels before the mineralizing process. These results revealed distinct switches of the specific molecular markers and
indicated a similar temporal expression to that observed in vivo recapitulating all stages of the differentiation program in vitro.
Received: 12 December 1996 / Accepted: 26 June 1997 相似文献