An umbrella review exploring the effect of radiotherapy for head and neck cancer patients on the frequency of jaws osteoradionecrosis.

OBJECTIVE: Efforts have been made to reduce epidemiological indicators of osteoradionecrosis in patients with head and neck cancer over recent years. This umbrella review aims to synthesize the information of the systematic reviews/meta-analyses investigating the effect of radiotherapy in patients with head and neck cancer on the frequency of osteoradionecrosis and to identify and analyze the gaps in current scientific literature. MATERIAL AND METHODS: A systematic review of systematic reviews with and without meta-analysis of intervention studies was conducted. Qualitative analysis of the reviews and their quality evaluation were performed. RESULTS: A total of 152 articles were obtained, and ten of them were selected for the final analysis, where six were systematic reviews and four were meta-analysis. According to the guide Assessing the Methodological Quality of Systematic Reviews (Amstar), eight articles included were of high quality and two of medium quality. These descriptive systematic reviews/meta-analyses included a total of 25 randomized clinical trials, showing that radiotherapy has positive effects on the frequency of osteoradionecrosis. Even though a reduction in the incidence of osteoradionecrosis was observed back in the history, in systematic reviews with meta-analysis, overall effect estimators were not significant. CONCLUSIONS: Differential findings are not enough to demonstrate that there is a significant reduction in the frequency of osteoradionecrosis in patients with head and neck cancer treated by radiation. Possible explanations are related to factors such as the type of studies analyzed, indicator of irradiated complication considered, and specific variables included in the analysis. Many systematic reviews did not address publication bias and did identify gaps in knowledge that require further clarification.

Anomalous phase behavior of first-order fluid-liquid phase transition in phosphorus.

Although the existence of liquid-liquid phase transition has become more and more convincing, whether it will terminate at a critical point and what is the order parameter are still open. To explore these questions, we revisit the fluid-liquid phase transition (FLPT) in phosphorus (P) and study its phase behavior by performing extensive first-principles molecular dynamics simulations. The FLPT observed in experiments is well reproduced, and a fluid-liquid critical point (FLCP) at T = 3000 ∼ 3500 K, P = 1.5-2.0 Kbar is found. With decreasing temperature from the FLCP along the transition line, the density difference (Δρ) between two coexisting phases first increases from zero and then anomalously decreases; however, the entropy difference (ΔS) continuously increases from zero. These features suggest that an order parameter containing contributions from both the density and the entropy is needed to describe the FLPT in P, and at least at low temperatures, the entropy, instead of the density, governs the FLPT.

Relationship between structural order and water-like anomalies in metastable liquid silicon: Ab initio molecular dynamics.

The relationship between structural order and water-like anomalies in tetrahedral liquids is still open. Here, first-principle molecular dynamics are performed to study it in metastable liquid Si. It is found that in T-P phase diagram, there indeed exists a structural anomaly region, which encloses density anomaly but not diffusivity anomaly. This is consistent with that of SW Si and BKS SiO2 but different from that of SPC/E water. Two-body excess entropy anomaly can neither capture the diffusivity, structural, and density anomalies, as it can in a two-scale potential fluid. In structural anomaly region, tetrahedrality order qtetra (measuring the extent to which an atom and its four nearest neighbours adopt tetrahedral arrangement) and translational order ttrans (measuring the tendency of two atoms to adopt preferential separation) are not perfectly correlated, which is different from that in SW Si and renders it impossible to use the isotaxis line to quantify the degree of structural order needed for water-like anomalies to occur. Along the isotherm of critical temperature Tc, ttrans/qtetra is approximately linear with pressure. With decreasing pressure along the isotherm below Tc, ttrans/qtetra departs downward from the line, while it is the opposite case above Tc.

The efficacy of fibrin sealant in knee surgery: A meta-analysis.

BACKGROUND: Fibrin sealant is frequently used in knee surgery as an adjuvant method for reducing postoperative bleeding, however, there is no consensus regarding the efficacy of fibrin sealant. HYPOTHESIS: Fibrin sealant achieves better efficacy in terms of blood loss control, transfusion rate and units in knee surgery compared with controls. METHODS: A search of the Cochrane Collaboration (2013 Issue 09), Embase (1974-2013.09), PubMed (1966-2013.09) and Chinese databases (up to 2013.09) were conducted. The Cochrane Collaboration's tool was used to assess for bias and data were analyzed by RevMan 5.29 software. RESULTS: This study included nine RCTs and four prospective comparative trials with a total of 1299 patients. Compared to the control, fibrin sealant achieved a decrease in hemoglobin reduction [MD=1.14, 95% CI (0.61-1.67)], transfusion rate [OR=0.36, 95% CI (0.25-0.51)], transfusion units [MD=0.47, 95% CI (0.24-0.71)], hospital stay [MD=2.22, 95% CI (0.56-3.88)] and the incidence of complications [OR=0.56, 95% CI (0.38-0.83)]. And it also reduced total blood loss, while there was no significant difference [MD=155.83, 95% CI (-525.02-213.15)]. CONCLUSION: Patients undergoing knee surgery would benefit from high-dose fibrin sealant with reduced transfusion rate and unit, hospital stay and complications, while they might benefit little from it in total blood loss. However, the effects of a low-dose of fibrin in knee surgery remain inconclusive.

Sustained focal cortical compression reduces electrically-induced seizure threshold.

Brain injury can often result in the subsequent appearance of seizures, suggesting an alteration in neural excitability associated with the balance between neuronal excitation and inhibition. The process by which this occurs has yet to be fully elucidated. The specific nature of the changes in excitation and inhibition is still unclear, as is the process by which the seizures appear following injury. In this study, we investigated the effects of focal cortical compression on electrically-induced localized seizure threshold in rats. Male Long Evans rats were implanted with stimulating screw electrodes in their motor cortices above the regions controlling forelimb movement. Initial seizure threshold was determined in the animals using a ramped electrical stimulation procedure prior to any compression. Following initial threshold determination, animals underwent sustained cortical compression and then following a 24 h recovery period had their seizure thresholds tested again with electrical stimulation. Reliability of threshold measurements was confirmed through repeated measurements of seizure threshold. Localized seizure threshold was significantly lowered following sustained cortical compression as compared with control cases. Taken together, the results here suggest a change in global brain excitability following localized, focal compression.

Vulnerability of the thalamic somatosensory pathway after prolonged global hypoxic-ischemic injury.

The aim of this study was to test the hypothesis that under prolonged global ischemic injury, the somatosensory thalamus and the cortex would manifest differential susceptibility leading to varying degrees of thalamo-cortical dissociation. The thalamic electrical responses displayed increasing suppression with longer durations of ischemia leading to a significant thalamo-cortical electrical dissociation. The data also point to a selective vulnerability of the network oscillations involving the thalamic relay and reticular thalamic neurons. An adult rat model of asphyxial cardiac arrest involving three cohorts with 3 min (G1, n=5), 5 min (G2, n=5) and 7 min (G3, n=5) of asphyxia respectively was used. The cortical evoked response, as quantified by the peak amplitude at 20 ms in the cortical evoked potential, recovers to more than 60% of baseline in all the cases. The multi-unit responses to the somatosensory stimuli recorded from the thalamic ventral posterior lateral (VPL) nuclei consists typically of three components: (1). the ON response (<30 ms after stimulus), (2). the OFF response (period of inhibition, from 30 ms to 100 ms after stimulus) and (3). rhythmic spindles (beyond 100 ms after stimulus). Asphyxia has a significant effect on the VPL ON response at 30 min (P<0.025), 60 min (P<0.05) and 90 min (P<0.05) after asphyxia. Only animals in G3 show a significant suppression (P<0.05) of the VPL ON response when compared to the sham group at 30 min, 60 min and 90 min after asphyxia. There was no significant reduction in somatosensory cortical N20 (negative peak in the cortical response at 20 ms after stimulus) amplitude in any of the three groups with asphyxia indicating a thalamo-cortical dissociation in G3. Further, rhythmic spindle oscillations in the thalamic VPL nuclei that normally accompany the ON response recover either slowly after the recovery of ON response (in the case of G1 and G2) or do not recover at all (in the case of G3).We conclude that there is strong evidence for selective vulnerability of thalamic relay neurons and its network interactions with the inhibitory interneurons in the somatosensory pathway leading to a thalamo-cortical dissociation after prolonged durations of global ischemia.

CSF cholinesterase in early-onset and late-onset Alzheimer's disease and multi-infarct dementia of Chinese patients.

Using Ellman spectrophotometric method we measured the total cholinesterase (ChE) activity in lumbar cerebrospinal fluid (CSF) of 13 persons without neurological disorder, 10 non-demented patients with cerebral infarcts, 17 patients with dementia of Alzheimer's type (DAT) (11 presenile, 6 senile cases), 10 patients with multi-infarct dementia (MID), 1 patient with Parkinson's disease associated with dementia. The ChE activity in CSF was significantly lower in the DAT group compared with age-matched control subjects (p < 0.001). This paper also analyses the possibility of using CSF ChE activity as a marker of DAT, and the relationships between its level of activity and the age of the patient at onset, stage of illness and severity of dementia as well as discrepancies in the data published so far. Previous work has shown that ChE activity in the brain tissue and CSF of MID is normal: therefore, if low ChE activity is found in the CSF of MID patients, as was obtained in 8 out of 10 cases in our series, the diagnosis of mixed dementia should be considered.