Noninvasive markers of liver steatosis and fibrosis after liver transplantation-Where do we stand?

In the last two decades,advances in immunosuppressive regimens have led to fewer complications of acute rejection crisis and consequently improved shortterm graft and patient survival.In parallel with this great success,long-term posttransplantation complications have become a focus of interest of doctors engaged in transplant medicine.Metabolic syndrome(MetS)and its individual components,namely,obesity,dyslipidemia,diabetes,and hypertension,often develop in the post-transplant setting and are associated with immunosuppressive therapy.Nonalcoholic fatty liver disease(NAFLD)is closely related to MetS and its individual components and is the liver manifestation of MetS.Therefore,it is not surprising that MetS and its individual components are associated with recurrent or“de novo”NAFLD after liver transplantation(LT).Fibrosis of the graft is one of the main determinants of overall morbidity and mortality in the post-LT period.In the assessment of post-LT steatosis and fibrosis,we have biochemical markers,imaging methods and liver biopsy.Because of the significant economic burden of post-LT steatosis and fibrosis and its potential consequences,there is an unmet need for noninvasive methods that are efficient and cost-effective.Biochemical scores can overestimate fibrosis and are not a good method for fibrosis evaluation in liver transplant recipients due to frequent post-LT thrombocytopenia.Transient elastography with controlled attenuation parameter is a promising noninvasive method for steatosis and fibrosis.In this review,we will specifically focus on the evaluation of steatosis and fibrosis in the post-LT setting in the context of de novo or recurrent NAFLD.

Study on a noninvasive method for rapid screening Human Serum albumin injectables by Raman spectroscopy

Human serum albumin(HSA)injectable product is a severely afflicted area on drug safety due to its high price and restricted supply.Raman spectroscopy performances high specificity on HSA detection and it is even possible to determine HSA injectable products noninvasively.In this study,we developed a noninvasive rapid screening method for of HSA injectable products by using portable Raman spectrometer.Qualitative models were established by using principal component analysis combined with classical least squares(PCA-CLS)algorithm,while quanti-tative model was established by using partial least squares(PLS)algorithm.Model transfer in different instruments of both the same and different apparatus modules was further discussed in this paper.A total of 34 HSA injectable samples collected from markets were used for verification.The identification results showed 100%accuracy and the predicted concentrations of those identified as true HSA were consistent with their labeled concentrations.The quantitative results also indicated that model transfer was excellent in the same apparatus modules of Raman spectrometer at all concentration levels,and still good enough in the different apparatus modules although the relative standard deviation(RSD)value showed a little increasing trend at low HSA concentration level.In conclusion,the method was proved to be feasible and efficient for screening HSA injections,especially on its screening speed and the consideration of glass containers.Moreover,with inspiring results on the model transfer,the method could be used as a universal screening mean to different Raman instruments.

Checkmate to liver biopsy in chronic hepatitis C?

Liver biopsy (LB) has traditionally been considered the gold standard for pretreatment evaluation of liver fibrosis in patients with chronic hepatitis C (CHC). However, LB is an invasive procedure with several shortcomings (intra-and interobserver variability of histopathological interpretation, sampling errors, high cost) and the risk of rare but potentially life-threatening complications. In addition, LB is poorly accepted by patients and it is not suitable for repeated evaluation. Further-more, the prevalence of CHC makes LB unrealistic to be performed in all patients with this disease who are candidates for antiviral therapy. The above-mentioned drawbacks of LB have led to the development of non-invasive methods for the assessment of liver fibrosis. Several noninvasive methods, ranging from serum marker assays to advanced imaging techniques, have proved to be excellent tools for the evaluation of liver fibrosis in patients with CHC, whereas the value of LB as a gold standard for staging fibrosis prior to antiviral therapy has become questionable for clinicians. Despite significant resistance from those in favor of LB, noninvasive methods for pretreatment assessment of liver fibrosis in patients with CHC have become part of routine clinical practice. With protease inhibitors-based triple therapy already available and substantial improvement in sustained virological response, the time has come to move forward to noninvasiveness, with no risks for the patient and, thus, no need for LB in the assessment of liver fibrosis in the decision making for antiviral therapy in CHC.

Different Types of Bone Fractures Observed by Terahertz Time-Domain Spectroscopy

Microcracks are common in compact bone,but their continued propagation can lead to macroscopic fractures.These microcracks cannot be visualized radiographically,necessitating alternative noninvasive methods to identify excessive microcracking and prevent fractures.In this study,terahertz time-domain spectroscopy(THz-TDS)was used to examine bone interiors near cracks resulting from loading in bovine tibia samples.Various loading configurations,such as impact,quasi-static loading,and fatigue loading,known to induce different types of micro-scale damage,were applied.The values of refractive index and absorption coefficient of the bone samples were then determined from the THz-TDS spectra acquired before loading and after fracture.The study revealed that different loading configurations led to varying terahertz optical coefficients associated with various types of bone fractures.Specifically,the refractive index notably increased under fatigue loading but remained relatively stable during quasi-static bending.The absorption coefficient of bone decreased only under fatigue loading.Furthermore,samples were subjected to axial and radial impacts without sustaining damage.Results indicated that in the undamaged state,the change in refractive index was smaller compared to after impact failure,while the change in absorption coefficient remained consistent after failure.Under radial impact loading,changes in refractive index and absorption coefficient were significantly more pronounced than under axial loading.Prior to loading,the measured value of refractive index was 2.72±0.11,and the absorption coefficient was 6.33±0.09 mm^(−1)at 0.5 THz.