SEARCH · PubMed Health

Results for “Mango”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 433 records · Page 24Linked to original sources

PubMed2004

Revision of distal femoral endoprosthetic arthroplasty with impacted morsellized allograft.

We report the use of contained impacted morsellized allograft to revise an aseptically loose, massive distal femoral cemented endoprosthetic replacement in a 27-year-old caucasian woman. The prosthesis was inserted 4 years earlier, following neoadjuvant chemotherapy and resection of a distal femoral high grade osteosarcoma. Impaction grafting was used to restore bone stock and maintain femoral length. The patient remains disease free with excellent function, at one year after revision with no evidence of loosening and maintenance of bone stock. We believe it is the first time this technique has been used in revision of a distal femoral endoprosthetic replacement.

Adult↗

PubMed2006

A gene-centered C. elegans protein-DNA interaction network.

Transcription regulatory networks consist of physical and functional interactions between transcription factors (TFs) and their target genes. The systematic mapping of TF-target gene interactions has been pioneered in unicellular systems, using "TF-centered" methods (e.g., chromatin immunoprecipitation). However, metazoan systems are less amenable to such methods. Here, we used "gene-centered" high-throughput yeast one-hybrid (Y1H) assays to identify 283 interactions between 72 C. elegans digestive tract gene promoters and 117 proteins. The resulting protein-DNA interaction (PDI) network is highly connected and enriched for TFs that are expressed in the digestive tract. We provide functional annotations for approximately 10% of all worm TFs, many of which were previously uncharacterized, and find ten novel putative TFs, illustrating the power of a gene-centered approach. We provide additional in vivo evidence for multiple PDIs and illustrate how the PDI network provides insights into metazoan differential gene expression at a systems level.

Animals↗

PubMed2003

The C. elegans Tousled-like kinase (TLK-1) has an essential role in transcription.

BACKGROUND: The Tousled kinases comprise an evolutionarily conserved family of proteins that have been previously implicated in chromatin remodeling, DNA replication, and DNA repair. Here, we used RNA mediated interference (RNAi) to determine the function of the C. elegans Tousled kinase (TLK-1) during embryonic development. RESULTS: TLK-1-deficient embryos arrested with a phenotype reminiscent of embryos that are broadly defective in transcription, and the expression of several reporter genes was dramatically reduced in tlk-1(RNAi) embryos. Furthermore, posttranslational modifications of RNA polymerase II (RNAPII) and histone H3 that have been correlated with transcription elongation, phosphorylation of the RNAPII CTD at Serine 2, and methylation of histone H3 at Lysine 36 were found at significantly reduced levels in tlk-1(RNAi) embryos as compared to wild-type. CONCLUSIONS: These results reveal a surprising requirement for a Tousled-like kinase in transcriptional regulation during development, likely during the elongation phase. In addition, our results confirm that the link between RNAPII phosphorylation and histone H3 methylation previously observed in budding yeast is functionally conserved in metazoans.

Animals↗

PubMed2004

ZEN-4/MKLP1 is required to polarize the foregut epithelium.

BACKGROUND: Epithelial tubes are a key component of organs and are generated from cells with distinct apico-basolateral polarity. Here, we describe a novel function during tubulogenesis for ZEN-4, the Caenorhabditis elegans ortholog of mitotic kinesin-like protein 1 (MKLP1), and CYK-4, which contains a RhoGAP (GTPase-activating protein) domain. Previous studies revealed that these proteins comprise centralspindlin (a complex that functions during mitosis to bundle microtubules), construct the spindle midzone, and complete cytokinesis. RESULTS: Our analyses demonstrate that ZEN-4/MKLP1 functions postmitotically to establish the foregut epithelium. Mutants that lack ZEN-4/MKLP1 express polarity markers but fail to target these proteins appropriately to the cell cortex. Affected proteins include PAR-3/Bazooka and PKC-3/atypical protein kinase C at the apical membrane domain, and HMR-1/cadherin and AJM-1 within C. elegans apical junctions (CeAJ). Microtubules and actin are disorganized in zen-4 mutants compared to the wild-type. CONCLUSION: We suggest that ZEN-4/MKLP1 and CYK-4/RhoGAP regulate an early step in epithelial polarization that is required to establish the apical domain and CeAJ.

Animals↗

PubMed2005

The C. elegans Tousled-like kinase contributes to chromosome segregation as a substrate and regulator of the Aurora B kinase.

BACKGROUND: The Aurora kinases control multiple aspects of mitosis, among them centrosome maturation, spindle assembly, chromosome segregation, and cytokinesis. Aurora activity is regulated in part by a subset of Aurora substrates that, once phosphorylated, can enhance Aurora kinase activity. Aurora A substrate activators include TPX2 and Ajuba, whereas the only known Aurora B substrate activator is the chromosomal passenger INCENP. RESULTS: We report that the C. elegans Tousled kinase TLK-1 is a second substrate activator of the Aurora B kinase AIR-2. Tousled kinase (Tlk) expression and activity have been linked to ongoing DNA replication, and Tlk can phosphorylate the chromatin assembly factor Asf. Here, we show that TLK-1 is phosphorylated by AIR-2 during prophase/prometaphase and that phosphorylation increases TLK-1 kinase activity in vitro. Phosphorylated TLK-1 increases AIR-2 kinase activity in a manner that is independent of TLK-1 kinase activity but depends on the presence of ICP-1/INCENP. In vivo, TLK-1 and AIR-2 cooperate to ensure proper mitotic chromosome segregation. CONCLUSIONS: The C. elegans Tousled kinase TLK-1 is a substrate and activator of the Aurora B kinase AIR-2. These results suggest that Tousled kinases have a previously unrecognized role in mitosis and that Aurora B associates with discrete regulatory complexes that may impart distinct substrate specificities and functions to the Aurora B kinase.

Animals↗

PubMed2004

Expression analysis of the gene encoding for the U-box-type ubiquitin ligase UBE4A in human tissues.

The Ubiquitination Factor E4A gene (UBE4A) encodes for a U-box-type ubiquitin ligase, originally described as an E4 ubiquitination factor. UBE4A is a mammalian homolog of Saccharomyces cerevisiae Ufd2. The UBE4A gene has been mapped on the human chromosome region 11q23.3, a critical region involved in some specific cancers such as neuroblastoma. Northern blots analysis on foetal and adult human tissues revealed a single band of approximately 7.5 kb transcript most abundant in the heart, skeletal muscle and kidney. We generated a polyclonal antibody to UBE4A and performed immunoblot and immunohistochemical analysis. The UBE4A protein appeared as a single band of approximately 125 kDa. UBE4A was present in the skeletal muscle, kidney and liver; a faint band was visible in peripheral blood leukocytes and spleen. We did not reveal expression of UBE4A in whole brain, colon, lung and heart. At the cellular level, UBE4A results predominantly expressed in the nucleus and the cytoplasm of cortical neurons and liver and in the nucleus of tubular kidney cells. In the liver, the nucleus of similar cells appeared to be unstained or stained at different levels suggesting that UBE4A may have a cell cycle dependent expression or a role of in cell cycle control. In conclusion, our results show that UBE4A is expressed in different tissues in a pattern that seems to be dependent from cell type and cell cycle and that UBE4A might have a specific role in different biochemical processes other than ubiquitination, including growth or differentiation.

Blotting, Northern↗

PubMed2006

A randomized trial of tranexamic acid in combination with cell salvage plus a meta-analysis of randomized trials evaluating tranexamic acid in off-pump coronary artery bypass grafting.

OBJECTIVES: We sought to evaluate the effectiveness of tranexamic acid in off-pump coronary artery bypass grafting surgery, either when used in combination with mechanical cell salvage or when used alone. METHODS: One hundred patients were randomized to either 2 g of tranexamic acid as an intravenous bolus before sternotomy or to placebo. Intraoperative and postoperative cell salvage was used in all patients. The primary end point was early postoperative blood loss (within 4 hours). To evaluate the efficacy of tranexamic acid in isolation, we also performed a meta-analysis of 4 randomized trials identified from a systematic literature search. The primary end point of the meta-analysis was red cell transfusion. RESULTS: In our randomized trial patients in the tranexamic acid group had a significant reduction in early postoperative blood loss, (median difference, 50 mL; 95% confidence interval, 15-100 mL; P < .01); however, there was no reduction in the frequency of blood component transfusion. Patients in the placebo group received a significantly larger volume of autotransfused red cells (median difference, 120 mL; 95% confidence interval, 0-220 mL; P = .02). The meta-analysis demonstrated a significant reduction in red cell transfusions in patients receiving tranexamic acid compared with those receiving placebo (risk ratio, 0.48; 95% confidence interval, 0.24-0.97; P = .041). There was also a reduction in the frequency of any allogeneic blood component transfusion, as well as a highly significant reduction in postoperative blood loss, in patients receiving tranexamic acid (P < .001). CONCLUSIONS: Tranexamic acid reduces blood loss and transfusion requirements in off-pump coronary artery bypass grafting surgery. A reduction in allogeneic blood transfusion was not evident in the presence of perioperative cell salvage. These data support the routine use of tranexamic acid in off-pump coronary artery bypass grafting surgery.

Adult↗

PubMed2006

Dynamic expression of the osmosensory channel trpv4 in multiple developing organs in zebrafish.

Transient receptor potential channels function in a wide spectrum of tissues and transduce sensory stimuli. The vanilloid (capsaicin) channel TRPV4 is sensitive to osmotic changes and plays a central role in osmoregulatory responses in a variety of organisms. We cloned a zebrafish trpv4 cDNA and assayed its expression during embryogenesis. trpv4 is expressed as maternal mRNA in 4-cell embryos and later zygotic expression is first observed in the forming notochord at the one somite stage. Notochord expression persists to 24 hpf when broad expression in the brain is observed. At 32 hpf trpv4 expression is observed in the endocardium, restricted primarily to the ventricular endothelium. Low level expression of trpv4 is also seen from 32-48 hpf in the pronephric kidney with strongest expression in the most distal nephron segment and in the cloaca. Expression is also observed in lateral line organs starting at 32 hpf, primarily in the hair cells. At 72 hpf, expression of trpv4 in heart, kidney, brain, and lateral line organs persists while expression in the notochord is down-regulated.

Amino Acid Sequence↗

PubMed2005

Gene expression and apoptosis induction in p53-heterozygous irradiated mice.

The role of the p53-genetic background in the expression of genes involved in either cell cycle checkpoint activation or apoptosis was evaluated in p53+/+ and p53+/- mouse strains at both basal levels and after DNA-induced damage. The spleen, colon, kidneys, lungs and liver of both strains were harvested from untreated animals and from mice exposed to 7.5 Gy of X-rays and sacrificed after 5 h. No significant differences were observed in the basal levels of p53 protein, CDKN1A and bax mRNA and spontaneous apoptosis, neither among the different organs within the same strain, nor between the same organ in the p53+/+ and p53+/- strains. After X-ray exposure, p53-dependent regulation was strikingly tissue-specific. In wild-type irradiated mice, p53 protein level increased after radiation treatment in all the organs analysed, whereas both CDKN1A and bax genes transcription increased in the spleen, colon and lungs, as assessed by means of quantitative RT-PCR. In p53+/- irradiated mice, on the contrary, a significant p53 induction was detected only in the spleen, while CDKN1A and bax genes levels increased in the spleen, colon and lungs, revealing the existence of different mechanisms of gene regulation in different organs. Apoptosis induction was observed in the spleen and colon of both strains, even if to lower extent in p53+/- mice compared to p53+/+ animals. In conclusion, in the spleen and colon, target gene transcription and apoptosis may be related to p53 genotype after DNA damage-induction. Moreover, our findings highlight the selectivity of p53 in transactivation following DNA damage in vivo, resulting in tissue-specific responses.

Animals↗

PubMed2005

Changes in respiratory mechanics with increasing degrees of airway obstruction in COPD: detection by forced oscillation technique.

The Forced Oscillation Technique (FOT) is a method for non-invasively assessing respiratory mechanics during spontaneous breathing, demanding little cooperation. The aim of this study was to test the ability of FOT to describe the changes in respiratory mechanics in progressive COPD. The study was performed in a control group formed by 21 healthy subjects and 79 outpatients with COPD, which were classified by spirometry, according to the degree of airway obstruction, in mild, moderate and severe groups. Resistive impedance data were submitted to linear regression analysis over the 4-16 Hz frequency range, which yielded the total respiratory system resistance extrapolated at 0 Hz (R0), the respiratory system conductance (Grs), mean respiratory resistance (Rm), and the resistance/frequency slope (S). Reactance data were interpreted using the mean values (Xm) over the 4-32 Hz frequency range, the dynamic compliance (Crs,dyn), the dynamic elastance (E(rs,dyn)), and the resonant frequency (fr) data. Considering the control and mild groups, the increase of airway obstruction resulted in a significant increase of R0 (P<0.008), Rm (P<0.001), and a significant reduction in Grs (P<0.002). Reactive parameters, Crs, dyn and Ers,dyn also presented significant modifications. The subsequent increase (mild to moderate) showed a significant raise of R(0) (P<0.007), S (P<0.001), and a reduction in Grs (P<0.015), while significant increases in Xrs (P<0.001), and Ers,dyn (P<0.02), and also a reduction in Crs, dyn (P<0.02) were also observed. In contrast to earlier stages, in the late stage of the airway obstruction increase (moderate to severe obstruction), resistive parameters did not present statistically significant modifications, while significant modifications were observed in Xrs (P<0.02), Crs, dyn (P<0.003) and Ers,dyn (P<0.003). The results of this study demonstrated that the FOT is useful for detecting the respiratory mechanics modifications in COPD patients. The initial phases of airway obstruction in COPD can be described mainly by resistive parameters, while in more advanced phases, reactive parameters seem to be more useful. Since the FOT has the advantage of being a simple method, such a technique may give a significant clinical contribution, representing an alternative and/or complement to the evaluation of respiratory mechanics by means of forced expiration.

Adult↗

PubMed2005

Elevation of susceptibility to ozone-induced acute tracheobronchial injury in transgenic mice deficient in Clara cell secretory protein.

Increases in Clara cell abundance or cellular expression of Clara cell secretory protein (CCSP) may cause increased tolerance of the lung to acute oxidant injury by repeated exposure to ozone (O3). This study defines how disruption of the gene for CCSP synthesis affects the susceptibility of tracheobronchial epithelium to acute oxidant injury. Mice homozygous for a null allele of the CCSP gene (CCSP-/-) and wild type (CCSP+/+) littermates were exposed to ozone (0.2 ppm, 8 h; 1 ppm, 8 h) or filtered air. Injury was evaluated by light and scanning electron microscopy, and the abundance of necrotic, ciliated, and nonciliated cells was estimated by morphometry. Proximal and midlevel intrapulmonary airways and terminal bronchioles were evaluated. There was no difference in airway epithelial composition between CCSP+/+ and CCSP-/- mice exposed to filtered air, and exposure to 0.2 ppm ozone caused little injury to the epithelium of both CCSP+/+ and CCSP-/- mice. After exposure to 1.0 ppm ozone, CCSP-/- mice suffered from a greater degree of epithelial injury throughout the airways compared to CCSP+/+ mice. CCSP-/- mice had both ciliated and nonciliated cell injury. Furthermore, lack of CCSP was associated with a shift in airway injury to include proximal airway generations. Therefore, we conclude that CCSP modulates the susceptibility of the epithelium to oxidant-induced injury. Whether this is due to the presence of CCSP on the acellular lining layer surface and/or its intracellular distribution in the secretory cell population needs to be defined.

Animals↗

PubMed2004

The coordinate regulation of pharyngeal development in C. elegans by lin-35/Rb, pha-1, and ubc-18.

Organ development is a complex process involving the coordination of cell proliferation, differentiation, and morphogenetic events. Using a screen to identify genes that function coordinately with lin-35/Rb during animal development, we have isolated a weak loss-of-function (LOF) mutation in pha-1. lin-35; pha-1 double mutants are defective at an early step in pharyngeal morphogenesis leading to an abnormal pharyngeal architecture. pha-1 is also synthetically lethal with other class B synthetic multivulval (SynMuv) genes including the C. elegans E2F homolog, efl-1. Reporter analyses indicate that pha-1 is broadly expressed during embryonic development and that its functions reside in the cytoplasm. We also provide genetic and phenotypic evidence to support the model that PHA-1, a novel protein, and UBC-18, a ubiquitin-conjugating enzyme that we have previously shown to function with lin-35 during pharyngeal development, act in parallel pathways to regulate the activity of a common cellular target.

Animals↗

PubMed2006

Role of T-box gene tbx-2 for anterior foregut muscle development in C. elegans.

During organogenesis, pluripotent precursor cells acquire a defined identity such as muscle or nerve. The transition from naïve precursor towards the differentiated state is characterized by sequential waves of gene expression that are determined by regulatory transcription factors. A key question is how transcriptional circuitry dictates the succession of events that accompanies developmental competence, cell fate specification and differentiation. To address this question, we have examined how anterior muscles are established within the Caenorhabditis elegans foregut (pharynx). We find that the T-box transcription factor tbx-2 is essential to form anterior pharyngeal muscles from the ABa blastomere. In the absence of tbx-2 function, ABa-derived cells initiate development normally: they receive glp-1/Notch signaling cues, activate the T-box gene TBX-38 and express the organ selector gene PHA-4/FoxA. However, these cells subsequently arrest development, extinguish PHA-4 and fail to activate PHA-4 target genes. tbx-2 mutant cells do not undergo apoptosis and there is no evidence for adoption of an alternative fate. TBX-2 is expressed in ABa descendants and depends on activation by pha-4 and repression by components of glp-1/Notch signaling. Our analysis suggests that a positive feedback loop between tbx-2 and pha-4 is required for ABa-derived precursors to commit to pharyngeal muscle fate.

Amino Acid Sequence↗

PubMed2004

Neonatal retroviral vector-mediated hepatic gene therapy reduces bone, joint, and cartilage disease in mucopolysaccharidosis VII mice and dogs.

Mucopolysaccharidosis VII (MPS VII) is a lysosomal storage disease caused by deficient beta-glucuronidase (GUSB) activity. Accumulation of glycosaminoglycans (GAGs) in bone, cartilage, and synovium likely contributes to reduced mobility in untreated MPS VII individuals. We previously reported that neonatal intravenous injection of a retroviral vector (RV) expressing canine GUSB resulted in hepatocyte transduction in mice and dogs, and secreted GUSB was taken up from blood by other organs. Here we report the effect of this therapy on bone, cartilage, and joint disease. Osteocytes and bone-lining cells from RV-treated MPS VII mice had GUSB activity, resulting in a marked reduction, as compared with untreated MPS VII mice, in lysosomal storage in bone and at the bone:growth plate interface where bone elongation occurs. Although chondrocytes did not have detectable GUSB activity and had little reduction in lysosomal storage, the thickness of the growth plate was reduced toward normal. These pathological changes were likely responsible for improvements in facial morphology and long bone lengths. The synovium had reduced hyperplasia and lysosomal storage, and the thickness of the articular cartilage was reduced. Similarly, RV-treated MPS VII dogs had improved facial morphology and reduced lysosomal storage in osteocytes and synovium, but not chondrocytes. Nevertheless, the internal area of the trachea was increased, and erosions of the femoral head were reduced. We conclude that neonatal gene therapy can improve bone and joint disease in MPS VII mice and dogs. However, better delivery of GUSB to chondrocytes will be necessary to achieve more profound effects in cartilage.

Animals↗

PubMed1996

Differences of regional coronary flow reserve assessed by adenosine thallium-201 scintigraphy early and six months after successful percutaneous transluminal coronary angioplasty or stent implantation.

This study assesses regional coronary flow reserve using adenosine thallium-201 scintigraphy early and 6 months after angiographically successful percutaneous transluminal coronary angioplasty (PTCA) or stent implantation. Seventeen consecutive men with a significant isolated left anterior descending coronary artery stenosis were scheduled for repeat coronary angiography and adenosine-planar thallium-201 scintigraphy within 24 hours and 6 months after successful PTCA (n = 8) or stent implantation (n = 9). After background subtraction, left ventricular segmental uptake was semiquantitatively assessed on thallium images. The perfusion defect severity was scored from 0 (normal) to 3. Coronary angiograms were analyzed using an automated edge contour detection computer analysis system. Data are expressed as mean value +/- 1 SD, and proportions as percentage. The residual narrowing was 17 +/- 8% after PTCA and 9 +/- 2% after stent implantation (p = 0.02). Twenty-four hours after the procedure, hypoperfused segments were detected in all patients (100%) and in 4 patients (44%) (p = 0.05), respectively. The total number of hypoperfused segments was greater after PTCA than after stent implantation (16 [40%] vs 7 [16%], p = 0.001, respectively) as was the perfusion defect severity (4.4 +/- 3.1 vs 1 +/- 1.2, p = 0.006). Six months after the procedure, 3 of the 5 patients who had undergone PTCA without restenosis still had reversible perfusion defects. None of the stent-treated patients had restenosis or reversible perfusion defects (p = 0.05). Among PTCA-treated patients without restenosis, the total number of hypoperfused segments and the perfusion defect severity were 9 of 25 (36%) and 0.8 +/- 0.8, respectively. Thus, a regional reduction in coronary flow reserve, occasionally observed early after successful stent implantation, is probably due to a transient alteration of small coronary vessels, as was also supported by the absence of perfusion defects 6 months after the procedure. The more severe impairment of regional coronary flow reserve observed early after successful PTCA is probably also due to angiographic underestimation of the residual stenosis, as suggested also by the persistence of reversible perfusion defects 6 months after the procedure in a few patients.

Adenosine↗

PubMed1996

Reducing false negatives in clinical practice: the role of neural network technology.

The fact that some cervical smears result in false-negative findings is an unavoidable and unpredictable consequence of the conventional (manual microscopic) method of screening. Errors in the detection and interpretation of abnormality are cited as leading causes of false-negative cytology findings; these are random errors that are not known to correlate with any patient risk factor, which makes the false-negative findings a "silent" threat that is difficult to prevent. Described by many as a labor-intensive procedure, the microscopic evaluation of a cervical smear involves a detailed search among hundreds of thousands of cells on each smear for a possible few that may indicate abnormality. Investigations into causes of false-negative findings preceding the discovery of high-grade lesions found that many smears had very few diagnostic cells that were often very small in size. These small cells were initially overlooked or misinterpreted and repeatedly missed on rescreening. PAPNET testing is designed to supplement conventional screening by detecting abnormal cells that initially may have been missed by microscopic examination. This interactive system uses neural networks, a type of artificial intelligence well suited for pattern recognition, to automate the arduous search for abnormality. The instrument focuses the review of suspicious cells by a trained cytologist. Clinical studies indicate that PAPNET testing is sensitive to abnormality typically missed by conventional screening and that its use as a supplemental test improves the accuracy of screening.

Cervix Uteri↗

PubMed1999

Cervicography screening for cervical cancer among 8460 women in a high-risk population.

OBJECTIVE: Cervicography was evaluated as a primary screening method for cervical cancer. STUDY DESIGN: Cervigrams of 8460 women were taken on enrollment into a population-based study of cervical neoplasia. Cervicography results were compared with a referent diagnosis determined by histologic analysis and 3 cytologic tests, and with the performance of conventional cytologic evaluation. RESULTS: Cervicography identified all 11 cancers, whereas cytologic testing missed 1. Cervicography yielded sensitivities for detecting high-grade squamous intraepithelial lesions or cancer of 49.3% overall (specificity, 95.0%), 54.6% in women younger than 50 years of age, and 26.9% in women 50 years of age and older. Cytologic testing yielded sensitivities for detecting high-grade squamous intraepithelial lesions or cancer of 77.2% overall (specificity, 94. 2%), 75.5% in women younger than 50 years of age, and 84.6% in women 50 years of age and older. CONCLUSIONS: Cytologic testing performed better than cervicography for the detection of high-grade squamous intraepithelial lesions. Cervicography performed marginally better than cytologic testing for the detection of invasive cervical cancer. Cervicography is not recommended for postmenopausal women.

Adolescent↗

PubMed1997

Pinching in longitudinal and alternate osteons during cyclic loading.

Pinching is a degrading phenomenon which occurs during cyclic loading of certain materials. A change in the slope of the deflection curve reveals pinching lesions, either flexural cracks or bond degradation, cause pinching. This paper investigates pinching for 20 longitudinal and 18 alternate fully calcified osteonic samples of cylindrical shape and 500 micron length. Each sample was axially loaded beyond the proportional limit using an electromechanical device acting as a transducer of the variations in length of the sample into changes in the resonance frequency of a microwave micrometer. A cubic polynomial served as a mathematical model to investigate the stress-strain diagrams at the first and last cycles through the study of strain limits, stiffness and pinching behaviours, and energy absorption. The hysteretic behaviour of the two types of osteons differs and is far from ideal. The presence of pinching may derive from the existence of longitudinal fibrils, in particular the yielding of the incompletely calcified ones. In longitudinal osteons consisting mainly of longitudinal collagen fibrils, the deformation under compression is not protected by lamellae consisting of transverse fibrils, therefore the lesions inducing pinching are magnified. In contrast, in alternate osteons, where the fibrils having a longitudinal orientation are reduced and protected by lamellae containing transversely oriented fibrils, the lesions-inducing pinching are lessened.

Adult↗