Identification of Mixtures of Two Types of Body Fluids Using the Multiplex Methylation System and Random Forest Models

Objective Body fluid mixtures are complex biological samples that frequently occur in crime scenes,and can provide important clues for criminal case analysis.DNA methylation assay has been applied in the identification of human body fluids,and has exhibited excellent performance in predicting single-source body fluids.The present study aims to develop a methylation SNaPshot multiplex system for body fluid identification,and accurately predict the mixture samples.In addition,the value of DNA methylation in the prediction of body fluid mixtures was further explored.Methods In the present study,420 samples of body fluid mixtures and 250 samples of single body fluids were tested using an optimized multiplex methylation system.Each kind of body fluid sample presented the specific methylation profiles of the 10 markers.Results Significant differences in methylation levels were observed between the mixtures and single body fluids.For all kinds of mixtures,the Spearman’s correlation analysis revealed a significantly strong correlation between the methylation levels and component proportions(1:20,1:10,1:5,1:1,5:1,10:1 and 20:1).Two random forest classification models were trained for the prediction of mixture types and the prediction of the mixture proportion of 2 components,based on the methylation levels of 10 markers.For the mixture prediction,Model-1 presented outstanding prediction accuracy,which reached up to 99.3%in 427 training samples,and had a remarkable accuracy of 100%in 243 independent test samples.For the mixture proportion prediction,Model-2 demonstrated an excellent accuracy of 98.8%in 252 training samples,and 98.2%in 168 independent test samples.The total prediction accuracy reached 99.3%for body fluid mixtures and 98.6%for the mixture proportions.Conclusion These results indicate the excellent capability and powerful value of the multiplex methylation system in the identification of forensic body fluid mixtures.

α-Synuclein pathology from the body to the brain:so many seeds so close to the central soil

α-Synuclein is a protein that mainly exists in the presynaptic terminals.Abnormal folding and accumulation of α-synuclein are found in several neurodegenerative diseases,including Parkinson’s disease.Aggregated and highly phospho rylated a-synuclein constitutes the main component of Lewy bodies in the brain,the pathological hallmark of Parkinson s disease.For decades,much attention has been focused on the accumulation of α-synuclein in the brain parenchyma rather than considering Parkinson s disease as a systemic disease.Recent evidence demonstrates that,at least in some patients,the initial α-synuclein pathology originates in the peripheral organs and spreads to the brain.Injection of α-synuclein preformed fibrils into the gastrointestinal tra ct trigge rs the gutto-brain propagation of α-synuclein pathology.However,whether α-synuclein pathology can occur spontaneously in peripheral organs independent of exogenous α-synuclein preformed fibrils or pathological α-synuclein leakage from the central nervous system remains under investigation.In this review,we aimed to summarize the role of peripheral α-synuclein pathology in the pathogenesis of Parkinson’s disease.We also discuss the pathways by which α-synuclein pathology spreads from the body to the brain.

Understanding the effects of excimer laser treatment on corrosion behavior of biodegradable Mg-1Ca alloy in simulated body fluid

In this study,a KrF excimer laser was used to modify the biodegradable Mg-1Ca alloy and the time-evolution degradation behavior of the alloy before and after laser treatment was investigated in simulated body fluid(SBF)solution using immersion tests and electrochemical impedance spectroscopy(EIS).A 5μm melted layer with a homogeneous microstructure and an MgO film on the surface were achieved by laser radiation.Corrosion observations(hydrogen evolution,morphology and corrosion products)and EIS results revealed an improvement of corrosion resistance after laser treatment for 48 h.It was found a two-layer structure developed after 2 h immersion on both the untreated and laser-treated alloys,but the sequence of forming the two layers was opposite and greatly influenced by the laser-treated layer.The time-evolution corrosion processes on the untreated and laser-treated alloys were discussed,providing a better understanding of corrosion behavior of biodegradable Mg alloys modified by excimer laser.

Corrosion fatigue of the extruded Mg-Zn-Y-Nd alloy in simulated body fluid

Magnesium alloys were considered to be used as biodegradable implants due to their biocompatibility,biodegradability and nontoxicity.However,under the simultaneous action of corrosive environment and mechanical loading in human body,magnesium alloys are easy to be affected by corrosion fatigue and stress corrosion cracking.In this work,the fatigue behavior of the extruded Mg-Zn-Y-Nd alloy used for vascular stents was studied both in air and in simulated body fluid(SBF).It was revealed that the fatigue limit of as-extruded Mg-Zn-Y-Nd alloy in air is about 65 MPa at 10^7 cycles,while there is no limit in SBF and shows a linear relationship between the fatigue life and stress amplitudes.The fatigue crack source in air was formed by the inclusions and defects.However,the stress corrosion and hydrogen embrittlement are the main reasons for the formation of the fatigue initial crack source in SBF.

Evaluation of Bioactive Properties of α and β Wollastonite Bioceramics Soaked in a Simulated Body Fluid

Dense natural wollastonite bioceramics (CaSiO3) were prepared by a sintering method, varying the pressing load and sintering temperature, in order to obtain different phases of wollastonite, and different physical properties in the materials. The products were characterized by TGA-DTA, XRD, FT-IR, SEM-EDS, TEM and XPS techniques. The results indicate the presence of two polymorphic phases of wollastonite, the β-wollastonite and α-wollastonite with a transition temperature of the β phase to α phase at approximately 1250℃. These materials were soaked in a simulated body fluid (SBF) during 1, 2 and 3 weeks, to study their solubility and bioactivity. The effect of different wollastonite phases on the solubility of Ca and Si, as well as the capacity of producing layers of “newly formed apatite” on the surfaces of these materials in SBF solution were analyzed.

Reflections on the Mechanism of Calcium Phosphate Nucleation on Titanium in Simulated Body Fluids

The results and main findings of studies reported in the literature in relation to the deposition of calcium phosphate on Ti in simulated body fluids are summarized. The effects of the surface hydroxyl groups and the sign of surface charge on the nucleation of calcium phosphate are reviewed. One major controversy among the conclusions of different studies is the order of adsorption of the calcium ions and the phosphate ions in the initial stage of immersion. A simple model based on the amphoteric nature of the hydroxyl groups on Ti is proposed in an attempt to delineate the nucleation process for calcium phosphate on Ti in simulated body fluids. HPO4^2- ions interact with the hydroxyl groups via ion exchange and/or electrostatic attraction, and Ca^2＋ ions, via electrostatic attraction only. There is no preferential order of adsorption. Seemingly inconsistent results in different studies possibly arise from different prior treatments of the samples, which affect the adsorption properties.

Formation of Apatite in Simulated Body Fluid

It is confirmed that the essential condition for glasses and glass-ceramics to bond to living bone is the formation of an apatite layer on their surfaces in the body.It is proposed that a hydrated silica formed on the surfaces of these materials in the body plays an important role in forming the surface apatite layer,which has not been proved yet.It is shown experimentally that a pure hydrated silica gel can induce the apatite formation on its surface in a simulated body fluid when its starting pH is increased from 7.2 to 7.4.

Critical biomarkers of hepatocellular carcinoma in body fluids and gut microbiota

Hepatocellular carcinoma(HCC)is the most prevalent primary liver cancer and one of the major causes of cancer-related death.The development of specific noninvasive or diagnostic markers from blood,urine and feces may represent a valuable tool for detecting HCC at an early stage.Biomarkers are considered novel potential targets for therapeutic intervention.It helps in the prediction of prognosis or recurrence of HCC,and also assist in the selection of appropriate treatment modality.We summarize the most relevant existing data about various biomarkers that play a key role in the progression of HCC.

Raman Spectroscopy for Forensic Identification of Body Fluid Traces: Method Validation for Potential False Negatives Caused by Blood-Affecting Diseases

Two critical issues in forensic science are identifying body fluid traces found at crime scenes and preserving them for DNA analysis. However, the majority of current biochemical tests for body fluid identification, which are applicable at the crime scene, are presumptive and destructive to the sample. Raman Spectroscopy provides a suitable alternative to current methods as a nondestructive, confirmatory, and potentially in field method. Our laboratory has developed a chemometric model for the identification of five main body fluids using Raman spectroscopy. This model was developed using samples obtained from healthy donors. Thus, it is of most importance for the forensic application of the method to validate its performance for donors with diseases that might affect the biochemical composition of body fluids. In this study, the developed method was validated using peripheral blood samples acquired from donors with Celiac Disease, Sickle Cell Anemia, and Type 2 Diabetes. It was shown that the method correctly identified all samples as peripheral blood indicating that no false positives could occur because the blood traces were originated from donors suffering from the diseases.

Body Fluid Changes, Cardiovascular Deconditioning and Metabolic Impairment Are Reversed 24 Hours after a 5-Day Dry Immersion

Dry immersion is an effective and useful model for research in physiology and physiopathology. The focus of this study was to provide integrative insight into renal, endocrine, circulatory, autonomic and metabolic effects of dry immersion. We assessed if the principal changes were restored within 24 h of recovery, and determined which changes were mainly associated with immersion-induced orthostatic intolerance. Five-day dry immersion without countermeasures, and with ad libitum water intake, standardized diet and a permitted short daily rise was performed in a relatively large sample for this experiment type (14 healthy young men). Reduction of total body water derived mostly from extracellular compartment, and stabilized rapidly at the new operating point. Decrease in plasma volume was estimated at 20% - 25%. Five-day immersion was sufficient to impair metabolism with a decrease in glucose tolerance and hypercholesterolemia, but was not associated with pronounced autonomic changes. Five-day immersion induced marked cardiovascular impairment. Immediately after immersion, over half of the subjects were unable to accomplish the 20-min 70° tilt;during tilt, heart rate and total peripheral resistance were increased, and stroke volume was decreased. However, 24 hours of normal physical activity appeared sufficient to reverse orthostatic tolerance and all signs of cardiovascular impairment, and to restitute plasma volume and extracellular fluid volume. Similarly, metabolic impairment was restored. In our study, the major factor responsible for orthostatic intolerance appeared to be hypovolemia. The absence of pronounced autonomic dysfunction might be explained by relatively short duration of dry immersion and daily short-time orthostatic stimulation.

Effects of different simulated fluids on anticorrosion biometallic materials

The corrosion behaviors of SUS316L stainless steel, Co Cr alloy and Ti 6Al 4V alloy in Ringer’s, PBS(-) and Hank’s solutions have been investigated. The results indicate that the corrosion of Ringer’s solution is the strongest, then followed by PBS(-) and Hank’s solution. The presence of HPO 2- 4, H 2PO - 4, SO 2- 4 and glucose in the PBS(-)and Hank’s solution probably reduces the corrosion inhibitor and corrosion current. The decrease of the solution’s pH significantly increases the corrosion rate and susceptibility to localized corrosion of SUS316L SS and Co Cr alloy. However, Ti 6Al 4V alloy exhibits an exceptional stability and has only a slight increase of corrosion rate with decreasing pH.

Construction and evaluation of in-house methylation-sensitive SNaPshot system and three classification prediction models for identifying the tissue origin of body fluid

The identification of tissue origin of body fluid can provide clues and evidence for criminal case investigations.To establish an efficient method for identifying body fluid in forensic cases,eight novel body fluid-specific DNA methylation markers were selected in this study,and a multiplex single base extension reaction(SNaPshot)system for these markers was constructed for the identification of five common body fluids(venous blood,saliva,menstrual blood,vaginal fluid,and semen).The results indicated that the in-house system showed good species specificity,sensitivity,and ability to identify mixed biological samples.At the same time,an artificial body fluid prediction model and two machine learning prediction models based on the support vector machine(SVM)and random forest(RF)algorithms were constructed using previous research data,and these models were validated using the detection data obtained in this study(n=95).The accuracy of the prediction model based on experience was 95.79%;the prediction accuracy of the SVM prediction model was 100.00%for four kinds of body fluids except saliva(96.84%);and the prediction accuracy of the RF prediction model was 100.00%for all five kinds of body fluids.In conclusion,the in-house SNaPshot system and RF prediction model could achieve accurate tissue origin identification of body fluids.

The Inferior Vena Cava Diameter as a Marker of Dry Weight in Chronic Hemodialyzed Patients

We have previously reported that the diameter of the inferior vena cava(IVC) reflects the amount of body fluid in hemodialyzed (HD) patients. The present study was undertaken to depict the criteria of IVC diameters for determining dry weight (DW) in anuric HD patients. In healthy subjects, the maximal diameters during quiet expiration (IVCe) and the minimal diameters during quiet inspiration (IVCi) were (16.7±3.2) and (5.7±5.4)mm,respectively (mean±SD).The collapsibility index (CI,1-IVCi/IVCe), which inversely correlates with the central venous pressure,was 0.68±0.29. In anuric HD patients,the IVCe/CI values before and after HD were 14.9±3.2/0.68±0.24 and 8.2±2.3/0.94±0.09, respectively. IVCe decreased proportionally to the amount of ultrafiltration. In HD patients with hypervolemic pulmonary edema, the IVCe and CI values were 22.4±2.9 and 0.22±0.11, respectively. We proposed that IVCe/CI after HD is (8±3)mm/0.9 ± 0.1 as the markers of DW in anuric HD patients and that an IVCe value≥22mm together with a CI≤0.22 implies the warning level of body fluid retention.

Super-hydrophobic stearic acid layer formed on anodized high purified magnesium for improving corrosion resistance of bioabsorbable implants

Magnesium and its alloys are ideal candidates for bioabsorbable implants.However,they can dissolve too rapidly in the human body for most applications.In this research,high purified magnesium(HP-Mg)was coated with stearic acid(SA)to slow the corrosion rate of magnesium in simulated body fluid at 37±1°C.HP-Mg was anodized(AC and DC voltages)to form an oxide/hydroxide layer,and then it was immersed in a SA solution.The SA coated layer surface,anodized layer,and the thickness of the oxide/hydroxide layer were investigated with Scanning Electron Microscopy(SEM).Electrochemical impedance spectroscopy(EIS)and potentiodynamic polarization(PDP)were used to estimate the corrosion rate of HP-Mg specimens.The results confirm that the hydrophobic coating can decrease the corrosion rate of HP-Mg by more than 1000x.The protectiveness of coated layer for anodized specimens with AC voltage continue for 2 and 3 weeks.For the HP-Mg coated anodized with DC voltage,the coated layer could improve the corrosion resistance for only a few days.

Initial formation of corrosion products on pure zinc in simulated body fluid

Zinc was recently suggested to be a potential candidate material for degradable coronary artery stent.The corrosion behavior of pure zinc exposed to r-SBF up to 336 h was investigated by electrochemical measurements and immersion tests. The morphology and chemical composites of the corrosion products were investigated by scanning electron microscope, grazing-incidence X-ray diffraction, X-ray photoelectron spectroscopy and Fourier transform infrared spectrometer. The results demonstrate that the initial corrosion products on the pure zinc mainly consist of zinc oxide/hydroxide and zinc/calcium phosphate compounds. The pure Zn encounters uniform corrosion with an estimated corrosion rate of 0.02-0.07 mmy;during the immersion, which suggests the suitability of pure Zn for biomedical applications.

Wear Behavior of Plasma Oxidized CoCrMo Alloy under Dry and Simulated Body Fluid Conditions

In this study, CoCrMo alloy was oxidized in plasma environment at the temperatures of 600 ℃ to 800 ℃ for 1 h to 5 h with 100% 02 gas and its tribological behavior was investigated. After the plasma oxidizing process, the compound and diffusion layers were formed on the surface. XRD results show that Cr203, a-Co and ε-Co phases diffracted from the modified layers after plasma oxidizing. The untreated and treated CoCrMo samples were subjected to wear tests both in dry and simulated body fluid conditions, and normal loads of 2 N and 10 N were used. For the sliding wear test, alumina balls were used as counter materials. It was observed that the wear resistance of CoCrMo alloy was increased after the plasma oxidizing process. The lowest wear rate was obtained from the samples that were oxidized at 800 ℃ for 5 h. It was detected that both wear environment and load have significant effects on the wear behavior of this alloy, and the wear resistance of oxidized CoCrMo alloy is higher when oxide-based counterface is used. The wear rates of both untreated and plasma oxidized samples increase under high loads.

Body fluid analog chlorination:Application to the determination of disinfection byproduct formation kinetics in swimming pool water

Disinfection by-products(DBPs)are formed in swimming pools by the reactions of bather inputs with the disinfectant.Although a wide range of molecules has been identified within DBPs,only few kinetic rates have been reported.This study investigates the kinetics of chlorine consumption,chloroform formation and dichloroacetonitrile formation caused by human releases.Since the flux and main components of human inputs have been determined and formalized through Body Fluid Analogs(BFAs),it is possible to model the DBPs formation kinetics by studying a limited number of precursor molecules.For each parameter the individual contributions of BFA components have been quantified and kinetic rates have been determined,based on reaction mechanisms proposed in the literature.With a molar consumption of 4 mol Cl2/mol,urea is confirmed as the major chlorine consumer in the BFA because of its high concentration in human releases.The higher reactivity of ammonia is however highlighted.Citric acid is responsible for most of the chloroform produced during BFA chlorination.Chloroform formation is relatively slow with a limiting rate constant determined at 5.50×10^-3 L/mol/sec.L-histidine is the only precursor for dichloroacetonitrile in the BFA.This DBP is rapidly formed and its degradation by hydrolysis and by reaction with hypochlorite shortens its lifetime in the basin.Reaction rates of dichloroacetonitrile formation by L-histidine chlorination have been established based on the latest chlorination mechanisms proposed.Moreover,this study shows that the reactivity toward chlorine differs whether L-histidine is isolated or mixed with BFA components.

Effect of corrosion on mechanical behaviors of Mg-Zn-Zr alloy in simulated body fluid

The main purpose of this paper is to investigate the effect of corrosion on mechanical behaviors of the Mg-Zn-Zr alloy immersed in simulated body fluid （SBF） with different immersion times. The corrosion behavior of the materials in SBF was determined by immersion tests. The surfaces of the corroded alloys were examined by SEM. The tensile samples of the extruded Mg-2Zn-0.8Zr magnesium alloy were immersed in the SBF for 0, 4, 7, 10, 14, 21 and 28 d. The tensile mechanical behaviors of test samples were performed on an electronic tensile testing machine. SEM was used to observe the fracture morphology. It was found that with extension of the immersion time, the ultimate tensile strength （UTS）, yield strength （YS） and elongation （EL） of the Mg-2Zn-0.8Zr samples decreased rapidly at first and then decreased slowly. The main fracture mechanism of the alloy transformed from ductile fracture to cleavage fracture with the increasing immersion times, which can be attributed to stress concentration and embrittlement caused by pit corrosion.

Physical and degradation properties of PLGA scaffolds fabricated by salt fusion technique

Tissue engineering scaffolds require a controlled pore size and interconnected pore structures to support the host tissue growth. In the present study, three dimensional （3D） hybrid scaffolds of poly lactic acid （PLA） and poly glycolic acid （PGA） were fabricated using solvent casting/particulate leaching. In this case, partially fused NaCl particles were used as porogen （200-300μ） to improve the overall porosity （≥90%） and internal texture of scaffolds. Differential scanning calorimeter （DSC） analysis of these porous scaffolds revealed a gradual reduction in glass transition temperature （Tg） （from 48°C to 42.5°C） with increase in hydrophilic PGA content. The potential applications of these scaffolds as implants were further tested for their biocompatibility and biodegradability in four simulated body fluid （SBF） types in vitro. Whereas, simulated body fluid （SBF） Type1 with the optimal amount of HCO 3 ions was found to be more appropriate and sensible for testing the bioactivity of scaffolds. Among three combinations of polymer scaffolds, sample B with a ratio of 75：25 of PLA： PGA showed greater stability in body fluids （pH 7.2） with an optimum degradation rate （9% to 12% approx）. X-ray diffractogram also confirmed a thin layer of hydroxyapatite deposition over sample B with all SBF types in vitro.

Corrosion Behavior ofAg-doped TiO2 Coatings on Commercially Pure Tita- nium in Simulated Body Fluid Solution

TiO2 films including different amounts of Ag obtained by sol-gel method on commercially pure titanium （CP-Ti） and the corrosion properties of Ag-doped TiO2 films were investigated by potentiodynamic polarisation and Electrochemical ImpedanceSpectroscopy （EIS） tests in Simulated Body Fluid （SBF） solution. The results were compared with untreated and un-doped samples. Surface characterizations before and after the corrosion tests were performed by the Scanning Electron Microscopy （SEM） and X-ray Diffraction （XRD） analysis. It was observed that Ag-doping for TiO2 films improved the corrosion resistance when compared with untreated and un-doped TiO2 film coated samples. The highest corrosion resistance was obtained from Ag-doped samples coated with a solution of 0.05 M Ag.