Post-operative management after total ankle arthroplasty: A systematic review of the literature.

BACKGROUND: Currently, there is no consensus on the most appropriate post-operative management for patients undergoing total ankle arthroplasty. The aim of this study is therefore to offer a systematic review of the pertaining literature to identify current post-operative protocols and describe possible differences. METHODS: A systematic review to identify recent studies concerning the post-operative management after total ankle arthroplasty was conducted. Five topics were analyzed: length of hospital stay, type and duration of immobilization, weight-bearing management, post-operative pharmacological therapies, adopted rehabilitation scheme. RESULTS: Eighty-four studies met the inclusion criteria and were included in the review process. Most of the papers appear to have conflicting opinions with no consensus and homogeneous protocols. CONCLUSION: Due to various methodological limitations, it is not possible to provide sufficiently supported evidence-based recommendations, and it is therefore difficult to determine the superiority of one post-operative protocol over the others after total ankle arthroplasty.

mBAND and mFISH analysis of chromosomal aberrations and breakpoint distribution in chromosome 1 of AG01522 human fibroblasts that were exposed to radiation of different qualities.

High-resolution multicolour banding FISH (mBAND) and multiplex FISH (mFISH) were used to analyse the aberrations of chromosome 1 in irradiated-AG01522 human primary fibroblasts. The cells were exposed to 1Gy of a panel of radiation of different qualities, such as X-rays, low-energy protons (28keV/µm), helium-ions (62keV/µm) and carbon-ions (96 and 252keV/µm). mBAND and mFISH analysis in calyculin-A G2-condensed chromosome spreads allowed us to detect intra- and interchromosome aberrations involving chromosome 1, including simple and complex-type exchanges, inversions (both para- and pericentric ones), deletions and rings. The data indicate that the induction of chromosomal exchanges was influenced by both Linear energy transfer (LET) and particle types. Moreover, the complex-to-simple exchanges ratio (C-ratio) and interchromosome to intrachromosome exchanges ratio (F-ratio) were evaluated by mFISH and mBAND techniques, respectively. Our results indicate that the C-ratio is a more reliable marker of radiation quality, with values that increased linearly in an LET-dependent manner. In addition, by means of mBAND analysis, the distribution of radiation-induced breakpoints along chromosome 1 was analyzed and compared with the expected distributions of the breaks. The expected values were calculated assuming a random distribution of the breakpoints. The data indicate that, irrespective of the radiation that was used, the breakpoints were non-randomly distributed along chromosome 1. In particular, breaks in the pericentromeric region were encountered at a higher frequency than expected. A deeper analysis revealed that breaks were not located in the constitutive heterochromatin (G-bands 1p11/1q11 and 1q12), but rather in a region comprised between 1p11.2 and 1p22.1, which includes G-light and G-dark bands.

Hyper-radiosensitivity and induced radioresistance and bystander effects in rodent and human cells as a function of radiation quality.

In the past two decades, a body of experimental evidences in vitro has shown the presence of a plethora of phenomena occurring after low-dose irradiation [including hypersensitivity and induced radioresistance (IRR), adaptive response, bystander effect (BE) and genomic instability], which might imply a non-linear behaviour of cancer risk curves in the low-dose region and question the validity of the linear no-threshold model for cancer risk assessment in such a dose region. In this framework, a systematic investigation have been undertaken on non-linear effects at low doses as a function of different radiation quality and cellular radiosensitivity and in terms of different biological end points. The present article reports the recent results on hyper-radiosensitivity and IRR and BE phenomena, in terms of clonogenic survival in V79 Chinese hamster cells and T98G human glioblastoma cells irradiated with protons and carbon ions with different energy, as a function of dose (and fluence).

mFISH analysis of irradiated human fibroblasts: a comparison among radiations with different quality in the low-dose range.

The present investigation aimed to characterise the shape of dose-response curve and determining the frequency distribution of various aberration types as a function of dose and radiation quality in AG01522 primary human fibroblasts in the 0.1- to 1-Gy dose range. For this purpose, the cells were irradiated with 7.7 and 28.5 keV µm(-1) low-energy protons, 62 keV µm(-1 4)He(2+) ions (LNL Radiobiology facility) or X rays and samples collected for 24-colour mFISH analysis. X rays and 7.7 keV µm(-1) protons displayed a quadratic dose-response curve solely for total and simple exchanges, whereas for high-linear energy transfer radiations, a linear dose-response curve was observed for all the aberration categories, with the exception of complex exchanges.

Induction and Repair of DNA DSB as Revealed by H2AX Phosphorylation Foci in Human Fibroblasts Exposed to Low- and High-LET Radiation: Relationship with Early and Delayed Reproductive Cell Death.

The spatial distribution of radiation-induced DNA breaks within the cell nucleus depends on radiation quality in terms of energy deposition pattern. It is generally assumed that the higher the radiation linear energy transfer (LET), the greater the DNA damage complexity. Using a combined experimental and theoretical approach, we examined the phosphorylation-dephosphorylation kinetics of radiation-induced γ-H2AX foci, size distribution and 3D focus morphology, and the relationship between DNA damage and cellular end points (i.e., cell killing and lethal mutations) after exposure to gamma rays, protons, carbon ions and alpha particles. Our results showed that the maximum number of foci are reached 30 min postirradiation for all radiation types. However, the number of foci after 0.5 Gy of each radiation type was different with gamma rays, protons, carbon ions and alpha particles inducing 12.64 ± 0.25, 10.11 ± 0.40, 8.84 ± 0.56 and 4.80 ± 0.35 foci, respectively, which indicated a clear influence of the track structure and fluence on the numbers of foci induced after a dose of 0.5 Gy for each radiation type. The γ-H2AX foci persistence was also dependent on radiation quality, i.e., the higher the LET, the longer the foci persisted in the cell nucleus. The γ-H2AX time course was compared with cell killing and lethal mutation and the results highlighted a correlation between cellular end points and the duration of γ-H2AX foci persistence. A model was developed to evaluate the probability that multiple DSBs reside in the same gamma-ray focus and such probability was found to be negligible for doses lower than 1 Gy. Our model provides evidence that the DSBs inside complex foci, such as those induced by alpha particles, are not processed independently or with the same time constant. The combination of experimental, theoretical and simulation data supports the hypothesis of an interdependent processing of closely associated DSBs, possibly associated with a diminished correct repair capability, which affects cell killing and lethal mutation.

Radiation response of chemically derived mitochondrial DNA-deficient AG01522 human primary fibroblasts.

Mitochondria are the main cellular source of Reactive Oxygen Species (ROS). Alterations of mitochondrial metabolism and consequent loss of mitochondrial membrane potential may lead to redox imbalance and in turn to DNA damage, chromosomal instability and apoptosis. On the other hand, impaired mitochondrial functions may either exacerbate the detrimental effects of geno- and cytotoxic agents or may bring beneficial cellular responses. To study the role of mitochondria within this framework, AG01522 human primary fibroblasts were incubated with the mitochondrial polymerase γ inhibitor 2',3'-dideoxycytidine (ddC), leading to mitochondrial DNA (mtDNA) depletion and to mitochondrial dysfunctions. The successful treatment toward mtDNA depletion was confirmed by Complex-IV subunit I (COX-I) immunofluorescence and western blot assays. mtDNA-depleted cells and their counterparts were ultrastructurally characterized by transmission electron microscopy. mtDNA-depleted cells showed dramatic mitochondrial alterations such as fragmentation and cristae disruption along with a reduction of the mitochondrial membrane potential and elevated levels of ROS. Despite increased ROS levels, we did not find any difference in telomere length between ddC-treated and untreated cells. The spontaneous rate of DNA double-strand breaks (DSBs) and chromosome aberrations was significantly enhanced in mtDNA-depleted cells whereas the induction of DSBs by low-Linear Energy Transfer (LET) (X-rays; 7.7keV/µm protons) and high-LET radiations (28.5keV/µm protons) did not differ when compared with normal cells. However, in irradiated cells impaired mitochondrial functions seemed to bring beneficial cellular responses to the detrimental effect of radiations. In fact, after X-irradiation mtDNA-depleted cells show less remaining unrejoined DSBs than normal cells and furthermore a lower induction of cytogenetic damage. Overall, these data show that active mitochondrial functions are required for the proper maintenance of cellular genome stability in primary fibroblasts.

Lack of hyper-radiosensitivity and induced radioresistance and of bystander effect in V79 cells after proton irradiation of different energies.

A huge body of evidence about the hyper-radiosensitivity and induced radioresistance (HRS/IRR) phenomena and the bystander effect (BE) is reported in the literature, in many cell types and in terms of various biological endpoints, after high- and low-linear energy transfer irradiation. However, the mechanisms underlying these effects together with their inter-relationship, and the correlation of HRS/IRR and BE phenomena with radiation quality are not yet well established and elucidated. To study these phenomena, the radiation response of V79 cells has been evaluated in terms of cell survival after irradiation with broad beams of 7.7- and 28.5-keV µm(-1) protons. HRS/IRR has been investigated also in terms of micronuclei and chromosomal aberration induction. The presence of BE has been investigated with a 'partial shielding irradiation' system, which prevents the irradiation of 35 % (on average) of the cell population. No clear evidence of HRS/IRR, nor of a significant BE response, can be identified in the low-dose region of V79 dose-response curves after proton irradiation of different energies.

Telomere alterations and genomic instability in long-term cultures of normal human fibroblasts irradiated with X rays and protons.

Telomeres are the end of linear chromosomes, responsible for chromosome stability and cell viability. It is well known that radiations are able to induce chromosome instability but it has not yet been investigated whether telomere structure is affected by the radiation exposure and if radiations with different quality act in a different way on telomeres. The effect of radiations with different quality on telomere structure and chromosome instability was analysed in human primary fibroblasts exposed to X rays or low-energy protons (28.5 keV µm(-1)). Telomere length was evaluated at different harvesting times from 24 h up to 360 h (15 days), whereas chromosome instability was evaluated in terms of sister chromatid exchanges (SCEs) (48 h from irradiation) and chromosome painting (360 h from irradiation). Results indicated a delayed telomere lengthening 360 h after X-ray treatment, whereas protons were able to induce such a lengthening shortly from irradiation as well as at longer harvesting times. Data obtained from chromosome instability analysis indicated an increase of SCE frequency only after proton irradiation, but, on the contrary, at the longer harvesting time chromosome painting analysis displayed a higher frequency of aberrations after X-ray treatment, suggesting a role of selective process against highly damaged cells.

Transient activation of the ALT pathway in human primary fibroblasts exposed to high-LET radiation.

It is well established that high-LET radiations efficiently induce chromosome aberrations. However, data on the effect of protons on telomere maintenance, as involved in genomic stability, are scarce and contradictory. Here we demonstrate that high-LET protons induce telomere lengthening in human primary fibroblasts and that this elongation does not involve the telomerase enzyme, supporting the hypothesis that high-LET radiations are able to activate a telomerase-independent mechanism. In tumor cells that lack telomerase, one or more non-telomerase mechanisms for telomere maintenance are present, which are termed alternative lengthening of telomeres (ALT). Since ALT cells are characterized by recombinational events at telomeres, known as telomeric-sister chromatid exchanges (T-SCE), and colocalization of telomeres and premyelocytic leukemia protein (PML), we analyzed both T-SCE and PML. Our results show that high-LET protons induce a 2.5-fold increase of T-SCE and a colocalization of PML protein and telomeric DNA. Furthermore, our data show that the ALT pathway can be activated in human primary cells after induction of severe DNA damage. Thus, since telomeres are known to be involved in chromosome maintenance, the present work may contribute in the elucidation of the mechanism by which ionizing radiation induces genomic instability.

DNA fragments induction in human fibroblasts by radiations of different qualities.

Experimental data on DNA double strand break (DSB) induction in human fibroblasts (AG1522), following irradiation with several radiation qualities, namely gamma rays, 0.84 MeV protons, 58.9 MeV u(-1) carbon ions, iron ions of 115 MeV u(-1), 414 MeV u(-1), 1 GeV u(-1), and 5 GeV u(-1), are presented. DSB yields were measured by calibrated Pulsed Field Gel Electrophoresis in the DNA fragment size range 0.023-5.7 Mbp. The DSB yields show little LET dependence, in spite of the large variation of the latter among the beams, and are slightly higher than that obtained using gamma rays. The highest yield was found for the 5 GeV u(-1) iron beam, that gave a value 30% higher than the 1 GeV u(-1) iron beam. A phenomenological method is used to parametrise deviation from randomness in fragment size spectra.

A comparative review of charged particle microbeam facilities.

At the low doses (and low dose rates) relevant to environmental and occupational radiation exposure (0-50 mSv), which are of practical concern for radiation protection, very few cells in the human organism experience more than one traversal by densely ionising particles in their lifetime, the intervals between the tracks, if any, typically being months or years. The biological effects of exactly one particle are not well known and cannot be simulated in vitro by conventional broad-beam exposures, due to the random Poisson distribution of tracks. Charged particle microbeam facilities are a unique tool that allows targeting of single cells and analysis of the induced damage on a cell-by-cell basis. In the past few years, many charged particle microbeam facilities for radiobiology have come into operation or are under development worldwide. Different experimental designs have been adopted at various laboratories regarding the achievement of micrometre (or sub-micrometre) ion beam size, by mechanical collimation or focusing, particle detection, and cell recognition and positioning systems. The different approaches are reviewed and discussed in this paper.

Telomere length in mammalian cells exposed to low- and high-LET radiations.

Telomeres are specialised nucleoprotein complexes that serve as protective caps of linear eukaryotic chromosomes. The loss of the ends of the chromosomes due to these un-rejoined double strand breaks (DSBs) may not be lethal to the cell, but may instead result in the loss of functional telomeres, chromosome fusions and initiation of breakage/fusion/bridge cycle-induced chromosome instability. The telomeres also participate in the process of DNA repair, as evidenced by 'de novo' synthesis of telomere repeats at DSBs and by the capacity of telomeres to binding the essential components of the DNA repair machinery. Based on the observation that high-LET radiations efficiently induce chromosome aberrations, it was tested whether protons were able to affect telomere structure. Human primary fibroblasts (HFFF2) and mouse embryonic fibroblasts (MEFs) were irradiated with 4 Gy of 3 MeV protons at the radiobiology facility of the INFN-LNL. Experiments with X rays were also carried out. Cells were fixed after either 24 h or 15 d from treatment. A difference in average telomere length, measured by quantitative fluorescence in situ hybridisation (Q-FISH), between X rays and protons treatment was observed. X rays are able to modify telomere length in HFFF2 harvested at a later time. On the other hand, 3 MeV low-energy protons induced, both in HFFF2 and in MEFs, a significant increase in telomere length at short as well as at long harvesting time periods from treatment. These results seem to indicate that lesions characterised by different complexity, as those expected after low-energy protons and those induced by damage similar to that induced by sparsely ionising radiation, are able to modulate telomere elongation at different time periods.

Gamma ray-induced bystander effect in tumour glioblastoma cells: a specific study on cell survival, cytokine release and cytokine receptors.

Recent experimental evidence has challenged the paradigm according to which radiation traversal through the nucleus of a cell is a prerequisite for producing genetic changes or biological responses. Thus, unexposed cells in the vicinity of directly irradiated cells or recipient cells of medium from irradiated cultures can also be affected. The aim of the present study was to evaluate, by means of the medium transfer technique, whether interleukin-8 and its receptor (CXCR1) may play a role in the bystander effect after gamma irradiation of T98G cells in vitro. In fact the cell specificity in inducing the bystander effect and in receiving the secreted signals that has been described suggests that not only the ability to release the cytokines but also the receptor profiles are likely to modulate the cell responses and the final outcome. The dose and time dependence of the cytokine release into the medium, quantified using an enzyme linked immunosorbent assay, showed that radiation causes alteration in the release of interleukin-8 from exposed cells in a dose-independent but time-dependent manner. The relative receptor expression was also affected in exposed and bystander cells.

DNA DSB induced in human cells by charged particles and gamma rays: experimental results and theoretical approaches.

PURPOSE: To quantify the role played by radiation track structure and background fragments in modulating DNA fragmentation in human cells exposed to gamma-rays and light ions. MATERIALS AND METHODS: Human fibroblasts were exposed in vitro to different doses (in the range from 40 - 200 Gy) of (60)Co gamma-rays and 0.84 MeV protons (Linear Energy Transfer, LET, in tissue 28.5 keV/microm). The resulting DNA fragments were scored under two electrophoretic conditions, in order to optimize separation in the size ranges 0.023 - 1.0 Mbp and 1.0 - 5.7 Mbp. In parallel, DNA fragmentation was simulated both with a phenomenological approach based on the "generalized broken-stick" model, and with a mechanistic approach based on the PARTRAC (acronym of PARticle TRACk) Monte Carlo code (1.32 MeV photons were used for the simulation of (60)Co gamma-rays). RESULTS: For both gamma-rays and protons, the experimental dose response in the range 0.023 - 5.7 Mbp could be approximated as a straight line, the slope of which provided a yield of (5.3 +/- 0.4) x 10(-9) Gy(-1) bp(-1) for gamma-rays and (7.1 +/- 0.6) x 10(-9) Gy(-1) bp(-1) for protons, leading to a Relative Biological Effectiveness (RBE) of 1.3 +/- 0.2. From both theoretical analyses it appeared that, while gamma-ray data were consistent with double-strand breaks (DSB) random induction, protons at low doses showed significant deviation from randomness, implying enhanced production of small fragments in the low molecular weight part of the experimental range. The theoretical analysis of fragment production was then extended to ranges where data were not available, i.e. to fragments larger than 5.7 Mbp and smaller than 23 kbp. The main outcome was that small fragments (<23 kbp) are produced almost exclusively via non-random processes, since their number is considerably higher than that produced by a random insertion of DSB. Furthermore, for protons the number of these small fragments is a significant fraction (about 20%) of the total number of fragments; these fragments remain undetected in these experiments. Calculations for 3.3 MeV alpha particle irradiation (for which no experimental data were available) were performed to further investigate the role of fragments smaller than 23 kbp; in this case, besides the non-random character of their production, their number resulted to be at least as much as half of the total number of fragments. CONCLUSION: Comparison between experimental data and two different theoretical approaches provided further support to the hypothesis of an important role of track structure in modulating DNA damage. According to the theoretical approaches, non-randomness of fragment production was found for proton irradiation for the smaller fragments in the experimental size range and, in a significantly larger extent, for fragments of size less than 23 kbp, both for protons and alpha particles.

Relative biological effectiveness of light ions in human tumoural cell lines: role of protein p53.

Protons and alpha particles of high linear energy transfer (LET) have shown an increased relative biological effectiveness (RBE) with respect to X/gamma rays for several cellular and molecular endpoints in different in vitro cell systems. To contribute to understanding the biochemical mechanisms involved in the increased effectiveness of high LET radiation, an extensive study has been designed. The present work reports the preliminary result of this study on two human tumoural cell lines, DLD1 and HCT116, (with different p53 status), which indicate that for these cell lines, p53 does not appear to take a part in the response to radiation induced DNA damage, suggesting an alternative p53-independent pathway and a cell biochemical mechanism dependent on the cell type.

The management of battle-fatigued soldiers: an occupational therapy model.

Battle fatigue is a soldier's response to the overwhelming environmental and psychological stressors associated with combat. Management efforts that emphasize replenishment of physiologic needs, structured occupation, and support of the affected soldier's occupational roles have yielded high return-to-duty rates. Although such effective battle-fatigue management principles, or "principles of battlefield psychiatry," are well described, they have not been explained in terms of theoretical foundation. The model of human occupation, an occupational therapy treatment model, is presented as a theoretical framework to explain the success of current battle-fatigue management principles and to guide continued refinement of the process of restoring battle-fatigued soldiers to duty.