Bioinformatics analysis and experimental verification of the prognostic and biological significance mediated by fatty acid metabolism related genes for hepatocellular carcinoma.

Background: Liver cancer is among the leading causes of death related to cancer around the world. The most frequent type of human liver cancer is hepatocellular carcinoma (HCC). Fatty acid (FA) metabolism is an emerging hallmark that plays a promoting role in numerous malignancies. This study aimed to discover a FA metabolism-related risk signature and formulate a better model for HCC patients' prognosis prediction. Methods: We collected mRNA expression data and clinical parameters of patients with HCC using the TCGA databases, and the differential FA metabolism-related genes were explored. To create a risk prognostic model, we carried out the consensus clustering as well as univariate and multivariate Cox regression analyses. 16 genes were used to establish a prognostic model, which was then validated in the ICGC dataset. The accuracy of the model was performed using receiver operating characteristic (ROC) analyses, decision curve analysis (DCA) and nomogram. The immune cell infiltration level of risk genes was evaluated with single-sample GSEA (ssGSEA) algorithm. To reflect the response to immunotherapy, immunophenoscore (IPS) was obtained from TCGA-LIHC. Then, the expression of the candidate risk genes (p < 0.05) was validated by qRT-PCR, Western blotting and single-cell transcriptomics. Cellular function assays were performed to revealed the biological function of HAVCR1. Results: According to the TCGA-LIHC cohort analysis, the majority of the FA metabolism-related genes were expressed differentially in the HCC and normal tissues. The prognosis of patients with high-risk scores was observed to be worse. Multivariate COX regression analysis confirmed that the model can be employed as an independent prognosis factor for HCC patients. Furthermore, ssGSEA analysis revealed a link between the model and the levels of immune cell infiltration. Our model scoring mechanism also provides a high predictive value in HCC patients receiving anti-PDL1 immunotherapy. One of the FA metabolism-related genes, HAVCR1, displays a significant differential expression between normal and HCC cell lines. Hepatocellular carcinoma cells (Huh7, and HepG2) proliferation, motility, and invasion were all remarkably inhibited by HAVCR1 siRNA. Conclusion: Our study identified a novel FA metabolism-related prognostic model, revealing a better potential treatment and prevention strategy for HCC.

Prognostic Nutritional Index Predicts Outcome of PD-L1 Negative and MSS Advanced Cancer Treated with PD-1 Inhibitors.

Purpose: Tumor mutational burden (TMB), microsatellite instability-high (MSI-H), and expression of programmed death ligand-1 (PD-L1) have emerged as predictive biomarkers for responsiveness to immune checkpoint inhibitors (ICIs) in several cancer types. However, for patients with negative PD-L1 expression, or microsatellite stability (MSS), some cases may experience favorable response to immunotherapy, and there is currently a lack of good relevant predictors. We tried to introduce several peripheral blood markers for predicting treatment outcome and immune-related adverse events (irAEs) in PD-L1 negative and MSS patients. Methods: A retrospective study of 142 PD-L1 negative and MSS patients was carried out. The association of peripheral blood markers including lactate dehydrogenase (LDH), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), albumin-to-globulin ratio (AGR), prognostic nutrition index (PNI), and other factors with clinicopathological characters and prognosis were assessed by Cox regression and Kaplan-Meier methods. Results: Lower level of PNI and poor performance status (ECOG score of 2) was correlated with significantly shorter overall survival (OS) and worse outcome of ICIs. The multivariate analysis revealed that PNI (for OS HR = 0.465, 95% CI: 0.236-0.916, p = 0.027; for PFS HR = 0.493, 95% CI: 0.251-0.936, p = 0.031) and ECOG score (for OS HR = 4.601, 95% CI: 2.676-7.910, p < 0.001; for PFS HR = 2.830, 95% CI: 1.707-4.691, p < 0.001) were independent prognostic factors for OS and PFS. NLR was related to the onset of irAEs. Conclusions: Pretreatment level of PNI and NLR, beyond PD-L1 expression and MSS, can improve the predictive accuracy for immunotherapy outcomes and has the potential to expand the candidate pool of patients for treatment with ICIs.

Prognostic value of neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio in gastric cancer.

The neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) have been presented to be a prognostic indicator in several types of cancer. However, these issues have not been concluded yet. The present study was therefore performed to determine the prognostic value of NLR and PLR in gastric cancer (GC).A total of 182 GC patients, diagnosed between January 2011 and January 2014, were enrolled in the study. The clinicopathological parameters, laboratory analyses, and outcomes were collected. The association between NLR, PLR, and clinicopathological characters was analyzed with univariate and multivariate analyses.NLR was significantly related to age (P = .026), surgery (P = .006), node status (P = .004), and clinical stage (P = .009). The median overall survival (OS) and progression-free survival (PFS) were poor in the High-NLR group (OS: 36.0 vs 20.5 months, P < .001, PFS: 33.0 vs 12.0 months, P < .001) and High-PLR group (OS: 31.5 vs 18.5 months, P = .003, PFS: 26.0 vs 11.0 months, P = .01). Multivariate analyses indicated both surgery [for OS hazard ratio (HR) = 2.092, 95% confidence interval (95% CI): 1.345-3.253, P = .001; for PFS HR = 1.939, 95% CI: 1.259-2.988, P = .003] and NLR (for OS HR = 1.585, 95% CI: 1.011-2.485, P = .045) were independent prognostic factors.Elevated NLR and PLR were related with poor prognosis in GC patients before treatment. The NLR was an independent prognostic factor for OS. More studies should be conducted to address the potential prognostic value of NLR and PLR in GC.

[Investigation of fibrous cultural materials by infrared spectroscopy].

Cultural fibrous material includes both important categories, i. e. textile and paper, consisting of precious cultural materials in museum, such as costume, painting, and manuscript. In recent years more and more connoisseur and conservator's concerns are, through nondestructive method, the authenticity and the ageing identification of these cultural relics especially made from fragile materials. In this research, we used attenuated total reflection infrared spectroscopy to identify five traditional textile fibers, alongside cotton, linen, wool, mulberry silk and tussah silk, and another five paper fibers alongside straw, wheat straw, long qisong, Chinese alpine rush and mulberry bar, which are commonly used for making Chinese traditional xuan paper. The research result showed that the animal fiber (wool, mulberry silk and tussah silk) and plant fiber (cotton and linen) were easier to be distinguished by comparing the peaks at 3 280 cm-1 belonging to NH stretching vibration and a serious peaks related to amide I to amide III. In the spectrum of wool, the peak at 1 076 cm-1 was assigned to the S-O stretching vibration absorption of cystine in wool structure and can be used to tell wool from silk. The spectrum of mulberry silk and tussah silk seems somewhat difficult to be identified, as well as the spectrum of cotton and linen. Five rural paper fibers all have obvious characteristic peaks at 3 330, 2 900 cm-1 which are related to OH and CH stretching vibration. In the fingerprint wavenumber range of 1 600 - 800 cm, the similar peaks also appeared at 1 370, 1 320 cm-1 and 1 162, 1 050 cm-1, both group peaks respectively are related to CH and CO vibration in the structure of cellulose and hemicellulose in paper fibers. Although there is more similarity of the infrared spectroscopy of these 5 paper fibers, some tiny difference in absorbance also can be found at 3 300 cm-1 and in the fingerprint range at 1 332, 1 203, and 1 050 cm-1 which are related to C-O-C vibration in cellulose. Moreover, in order to explore direct and simple method to identify different materials with similar spectrum,. the principal component analysis (PCA) was applied to separate cotton and linen, mulberry silk and tussah silk, as well as five paper fibers. To eliminate and reduce the spectral scattering caused by sample uneven surface roughness, the multiplicative scatter correction (MSC) has been applied based on total spectral data. The result showed that the score plot using the first two principal components can effectively categorize both group textiles of cotton and linen, as well as mulberry silk and tussah silk, and they have similar chemical structure. For five paper fibers, the PCA was applied in different spectral range (918-550, 1 280-918, 1 700-1 280 and 3 800-2 800 cm-1), and the best result appeared in the range from 3 800 to 2 800 cm-1, in which the five paper fibers can be well categorized. This research showed that infrared spectroscopy combined with principal component analysis has great potential advantage on identifying fibrous materials with similar structure.

Utility of uric acid as a risk marker of extubation success in chronic obstructive pulmonary disease.

BACKGROUND: The objective of this observational study was to determine whether there is an association between extubation success and uric acid in chronic obstructive pulmonary disease patients with mechanical ventilation admitted to the intensive care units, and identify the risk markers for extubation success in COPD patients with mechanical ventilation. METHODS: Consecutive COPD patients with intubation were screened at baseline. The study included patients on mechanical ventilation (MV) for over 12 hours and who, in the process of weaning, were subjected to low-level pressure support. Exclusion criteria were age under 18 years, ventilation via tracheotomy, and patients failing to cooperate for different reasons. The final study population consisted of 106 patients. Demographic, clinical, laboratory, and mechanical ventilation parameters were carefully recorded. Logistic regression was used for the multivariate analysis of independent risk factors. RESULTS: Uric acid on admission, duration of mechanical ventilation, pressure support ventilation, and APACHE II score on admission were significantly higher in COPD patients with extubation failure than in those with extubation success (p < 0.05), but lower tidal volume before weaning was observed in COPD patients with extubation failure. Among these patients, multiple logistic analyses indicated the independent risk factors for extubation success in the COPD subjects included serum uric acid level, APACHE II score on admission, and duration of mechanical ventilation. The diagnosis analysis showed that higher uric acid level and APACHE II score on admission and longer duration of mechanical ventilation had a significant ability to reflect extubation success in the COPD patients with respiratory failure. CONCLUSIONS: The novel finding of this study is that the extubation failure in COPD patients with respiratory failure is strongly related to serum uric acid level, APACHE II score on admission, and duration of mechanical ventilation. These results might be helpful for selecting the best time to remove the tracheal intubation and improving extubation success rate in COPD patients with respiratory failure.

[Determination of Trace Lead in Water by UV-Visible Diffuse Reflectance Spectroscopy Combined with Surfactant and Membrane Filtration-Enrichment].

In this paper, a method of determination of trace lead in water by UV-Visible diffuse reflectance spectroscopy combined with surfactant and membrane filtration enrichment was proposed. In the NH3 x H2O-NH4Cl buffer solution with pH 8.5, the lead(II) ion would react with dithizone to form the red complex under vigorous stirring, which is hydrophobic and can be enriched by the mixed cellulose ester membrane. In addition, the nonionic surfactant Polyoxyethylene lauryl ether (Brij-30) was added into the solution to improve the enrichment efficiency, then visible diffuse reflectance spectra of the membrane were measured directly after the membrane were naturally dried. We also optimized the reaction conditions which may affect the complexation reaction process, such as type of surfactants, the concentration of the surfactant, the reaction acidity, the concentration of dithizone as well as the reaction time. The research results show that under the optimum conditions, a good linear correlation between absorbance at 485 nm and concentration of lead in the range of 5.0-100.0 microg x L(-1) was obtained with a squared correlation coefficient (R2) of 0.9906, and the detection limit was estimated accordingly to be 2.88 microg x L(-1). To determine real water sample, the interference from some potential coexisting ions was also studied at the optimal conditions when the concentration of lead (II) ion standard solution was fixed to 20 microg x L(-1). The results indicate that the following ions cannot interfere in the determination of lead with the proposed method: 500 times of the K+, Na+, Ca2+, Mg2+, NH4+, NO3-, Cl-, CH3COO-, SO4(2-); 10 times of the Al3+ (using 10% NaF as a masking reagent to avoid the interference); 10 times of the Fe3+ (using 10% NaF and 10% sodium potassium tartrate as masking reagents); 10 times of Hg2+ or Zn2+ (using 10% NaSCN and 10% potassium sodium tartrate as masking reagents); the same amount of Cd2+, Cu2+. The proposed method was applied to the determnation of lead (II) in bottled water as a real sample. The determination results show good agreements between the proposed method and graphite furnace atomic absorption spectrometry (GFAAS) method. The recoveries in case of spiked real samples were between 95.4% and 104.5%, and the standard deviations (SD) were between 0.5 micro x L(-1) and 1.5 microg x L(-1), which indicate that the method developed in the present work with advantages of accuracy, simpleness, sensitiveness are of potential application for the determination of trace lead in water samples.

Aerobic oxidation of hydroxymethylfurfural and furfural by using heterogeneous Cox Oy -N@C catalysts.

2,5-Furandicarboxylic acid (FDCA) is considered to be a promising replacement for terephthalic acid since they share similar structures and properties. In contrast to FDCA, 2,5-furandicarboxylic acid methyl (FDCAM) has properties that allow it to be easily purified. In this work, we reported an oxidative esterification of 5-hydroxymethylfurfural (HMF) and furfural to prepare corresponding esters over Cox Oy -N@C catalysts using O2 as benign oxidant. High yield and selectivity of FDCAM and methyl 2-furoate were obtained under optimized conditions. Factors which influenced the product distribution were examined thoroughly. The Cox Oy -N@C catalysts were recycled five times and no significant loss of activity was detected. Characterization of the catalysts could explain such phenomena. Using XPS and TGA, we made a thorough investigation of the effects of ligand and pyrolysis temperature on catalyst activity.

Prognostic value of preoperative serum tumor markers in gastric cancer.

AIM: To evaluate the prognostic value of preoperative carcinoembryonic antigen (CEA), carbohydrate antigen (CA)19-9, and CA50 in patients undergoing D2 resection. METHODS: We evaluated 363 patients with gastric cancer who underwent gastrectomy at our hospital from January 2006 to December 2009. Blood samples were obtained from each patient within 1 wk before surgery. The cut-off values for serum CEA, CA19-9, and CA50 were 5 ng/mL, 37 U/mL, and 20 U/mL, respectively. The correlation between preoperative tumor marker levels and prognosis was studied by means of univariate and multivariate analyses. RESULTS: The preoperative serum positive rates of CEA, CA19-9 and CA50 were 24.0%, 18.9% and 24.5%, respectively. The positivity rate of serum CEA was significantly correlated with age (P < 0.001), sex (P = 0.022), tumor size (P = 0.007) and depth of invasion (P = 0.018); CA19-9 with tumor size (P = 0.042) and lymph node metastasis (P < 0.001); and CA50 only with lymph node metastasis (P = 0.001). In multivariate analysis, tumor size, T category, N category, vascular or neural invasion, and adjuvant chemotherapy were independent prognostic factors for overall survival. CA19-9 had an independent prognostic significance in patients without adjuvant chemotherapy (P = 0.027). CONCLUSION: Preoperative serum CEA, CA19-9 and CA50 are prognostic in patients with gastric cancer. Only CA19-9 is an independent prognostic factor after surgery without adjuvant chemotherapy.

[Identification of Nanfeng mandarin from different origins by using near infrared spectroscopy coupled with principal components analysis].

The identification of Nanfeng mandarins from different origins was developed by using near infrared spectroscopy (NIR) and principal components analysis (PCA). Mandarins from different places in one orchard, and from different orchards in three towns of Nanfeng county were studied. Also differences among Shaowu, Liucheng and Nanfeng were investigated. Furthermore, the effect of storage time of mandarins on the PCA model was considered. The results demonstrate that there was no clear diversity of the mandarins in one origin but great differences existed among different ones. And the storage time of mandarins played little role in the discrimination model. The method of multiple scattering correction (MSC) coupled with second derivative was selected to build PCA discrimination models compared with other data pretreatment methods. The proposed model would be a reference method for origin identification of Nanfeng mandarin.

At-line monitoring of key parameters of nisin fermentation by near infrared spectroscopy, chemometric modeling and model improvement.

An analytical procedure has been developed for at-line (fast off-line) monitoring of 4 key parameters including nisin titer (NT), the concentration of reducing sugars, cell concentration and pH during a nisin fermentation process. This procedure is based on near infrared (NIR) spectroscopy and Partial Least Squares (PLS). Samples without any preprocessing were collected at intervals of 1 h during fifteen batch of fermentations. These fermentation processes were implemented in 3 different 5 l fermentors at various conditions. NIR spectra of the samples were collected in 10 min. And then, PLS was used for modeling the relationship between NIR spectra and the key parameters which were determined by reference methods. Monte Carlo Partial Least Squares (MCPLS) was applied to identify the outliers and select the most efficacious methods for preprocessing spectra, wavelengths and the suitable number of latent variables (n (LV)). Then, the optimum models for determining NT, concentration of reducing sugars, cell concentration and pH were established. The correlation coefficients of calibration set (R (c)) were 0.8255, 0.9000, 0.9883 and 0.9581, respectively. These results demonstrated that this method can be successfully applied to at-line monitor of NT, concentration of reducing sugars, cell concentration and pH during nisin fermentation processes.

[Infrared spectroscopy investigation on conformational change of silk fiber induced by gaseous organic acids existing in museum].

Study on the impact of pollutants on cultural materials in storing or displaying micro-environment in museum is considered as very important for the preservation of cultural relics and its aging prevention. This paper applied the Fourier transform infrared (attenuated total reflection) technique to assess silk structural changes under volatile organic acids (formic acid/acetic acid), which usually come from decorative materials emission and commonly exist in the surface or around cultural materials. The focus of this work was on investigating the changes of peptide bond in the area of amide I-amide III, as well as the peptide chains (GlyAla), characteristic region. The structural and conformational changes in silk fiber treated with gaseous formic and acetic acid were assessed. The results indicate that both the gaseous acids can weaken the intermolecular hydrogen bond in fiber peptide, based on the spectral changes in the increased intensity of amide I (1 617 cm(-1)), the narrowing amide II peak (1 515 cm(-1)), the increased intensity of random coil conformation in amide III peak (1 230 cm(-1)), and the decreased fiber crystallinity as well. The obvious secondary structural conformation occurred when the concentration of gaseous formic acid reached 8.1 mg x m(-3) in simulated environment. The conformational transformation was supported by the observation of the rapidly reduced random coil conformation, the increased short peptide chains (GlyAla)n with beta-sheet conformation characteristic peak (1 000, 975 cm(-1)), and the enhanced fiber crystallinity degree as well. In contrast, gaseous acetic acid has less impact on the amide I and amide II bond based on the spectral changes, but it did promote random coil conformation and decreased fiber crystallinity. This work also provides a potential application of the infrared spectroscopy in non-destructive investigation of silk in-situ.

Modified mesoporous silica materials for on-line separation and preconcentration of hexavalent chromium using a microcolumn coupled with flame atomic absorption spectrometry.

A modified SBA-15 mesoporous silica material NH(2)-SBA-15 was synthesized successfully by grafting γ-aminopropyl-triethoxysilane. The material was characterized using transmission electron microscopy (TEM) and Fourier transform infrared/Raman (FT-IR/Raman) spectroscopy, and used for the first time in a flow injection on-line solid phase extraction (SPE) coupled with flame atomic absorption spectrometry (FAAS) to detect trace Cr (VI). Effective sorption of Cr (VI) was achieved at pH 2.0 with no interference from Cr (III) and other ions and 0.5 mol L(-1) NH(3)·H(2)O solution was found optimal for the complete elution of Cr (VI). An enrichment factor of 44 and was achieved under optimized experimental conditions at a sample loading of 2.0 mL min(-1) sample loading (300 s) and an elution flow rate of 2.0 mL min(-1) (24s). The precision of the 11 replicate Cr (VI) measurements was 2.1% at the 100 µg L(-1) level with a detection limit of 0.2 µg L(-1) (3s, n=10) using the FAAS. The developed method was successfully applied to trace chromium determination in waste water. The accuracy was validated using a certified reference material of riverine water (GBW08607).

[Study of mobile Raman spectroscopy for rapid evaluation of deteriorating of art materials under UV irradiation].

Identification and characterization of materials used in cultural heritage and conservation can provide important information for dating, authentication and deteriorating situation in general. How to extract useful information from these materials in-situ is one of the main concerns. Application of mobile Raman spectroscopy for this purpose has great attentions for scientists and conservators. The present paper aims to investigate the mobile Raman spectroscopy in studying the effect of UV light on the deterioration of silk, seal ink and Chinese traditional colorants such as kermes, vermillion and zhubiao, which is commonly appeared on painted works of art, and the silk sample is also often used as an consolidant for repairing destroyed textile objects. Spectra were recorded from predefined regions on the samples before and after ultraviolet radiation with 360 nm wavelength and 0.68 W x m(-2) intensity. The result revealed obvious effects of ultraviolet radiation on the materials simulated in this research. The original kind of seal ink has been clearly identified. The changes in spectra of all samples with and without UV radiation were further distinguished and studied. The result will assist for scientists and conservators to determine the safe treatments and suitable environmental condition for storage, display and transport. The result will also help for studying mechanism of deterioration of museum objects influenced by environmental factors. The mobile Raman spectroscopy showed a suitable and convenient means for in-situ non-destructive detection and study of deterioration in practical conditions.

[The study on linear relationship between concentration and surface-enhanced Raman spectroscopy (SERS) signal of thymine in improved Ag sol].

The authors used polymer as a stable medium to protect Ag sol to get a stable signal for the unstable Ag sol. Poly-acrylic acid sodium was selected as the stable medium, which had a little effect on the SERS of thymine and made the SERS signal stable for thirty days. After aborative consideration and some trials, pyridine was picked as an internal standard for the quantitative detection of thymine. A linear correlation between the concentration of thymine and the ratio of thymine signal to pyridine signal intensity was obtained over a range of 2 x 10(-4)1 x 10(-3) mol x L(-1) with a correlation coefficient R2 of 0.975 4. The regression equation is: y = 3.143x + 0.348 7. The proposed method has the potential for quantitative analysis of the trace compounds having SERS effects.

[Expression of Bcl-2 and Fas and apoptosis of T lymphocyte in the peripheral blood of patients with end-stage renal diseases].

OBJECTIVE: To investigate the expression of Bcl-2 and Fas and the apoptosis of T lymphocyte in the peripheral blood of patients with end-stage renal diseases; and to test the impact of various dialysis membranes on the apoptosis of T lymphocyte. METHODS: T lymphocyte was cultured with the stimulation of Phytohemagglutinin (PHA) for 24 h. The apoptosis of T lymphocyte was measured by flow cytometry. The expression of Bcl-2 and Fas was measured with immunohistochemical approach. A total of 10 non-dialyszed (ND) patients, 45 maintenance hemodialysis patients with cellulose acetate (CA) membrane, low-flux (PS-LF) and high-fluxpolusulfone (PS-HF) membrane, and 8 healthy volunteers (HC) participated in the study. RESULTS: The patients with end-stage renal diseases had greater apoptosis of T lymphocyte than healthy volunteers (P < 0.01). The patients undergoing hemodialysis with CA membrane had greater apoptosis of T lymphocyte than those with PS-LF and PS-HF membranes (P < 0.05). The expression of Bcl-2 in T lymphocyte of patients with end-stage renal diseases was lower than that of healthy valunteers (P < 0. 01). The apoptosis of T lymphocyte was negatively correlated with the expression of Bcl-2 (r = -0. 83, P < 0.01). The expression of Fas in T lymphocyte of patients with end-stage renal diseases was greater than that of healthy valunteers (P < 0.01). The apoptosis of T lymphocyte was positively correlated with the expression of Fas (r = 0.81, P < 0.01). CONCLUSION: Patients with end-stage renal diseases may experience accelerated apoptosis of T lymphocyte, which is associated with the high expression of Fas and low expression of Bcl-2 in T lymphocyte. The apoptosis of T lymphocyte is also influenced by the permeability of the dialysis membranes.

[A study on HLA-DQB1 allele associated with genetic susceptibility to duodenal ulcer in Guangdong Hans].

OBJECTIVE: To study the genetic susceptibility of HLA-DQB1 alleles to duodenal ulcer in Chinese Hans from Guangdong area around. METHODS: Hundred and five patients with duodenal ulcer and hundred and five healthy controls were examined for HLA-DQB1 genotypes. HLA-DQB1 allele typing was carried out by polymerase chain reaction with sequence specific primers (PCR-SSP). RESULTS: The allele frequency of HLA-DQB1*0602 in patients with duodenal ulcer (64.8%) was significantly higher than that in healthy controls (14.3%). CONCLUSION: These findings suggest that HLA-DQB1*0602 is a susceptible gene to duodenal ulcer in Guangdong Hans of China. And at HLA-DQB1 site, there are immunogenetic differences between duodenal ulcer patients and healthy controls.

Moving window cross validation: a new cross validation method for the selection of a rational number of components in a partial least squares calibration model.

A new cross validation method called moving window cross validation (MWCV) is proposed in this study, as a novel method for selecting the rational number of components for building an efficient calibration model in analytical chemistry. This method works with an innovative pattern to split a validation set by a number of given windows that move synchronously along proper subsets of all the samples. Calculations for the mean value of all mean squares error in cross validations (MSECVs) for all splitting forms are made for different numbers of components, and then the optimal number of components for the model can be selected. Performance of MWCV is compared with that of two cross validation methods, leave-one-out cross validation (LOOCV) and Monte Carlo cross validation (MCCV), for partial least squares (PLS) models developed on one simulated data set and two real near-infrared (NIR) spectral data sets. The results reveal that MWCV can avoid a tendency to over-fit the data. Selection of the optimal number of components can be easily made by MWCV because it yields a global minimum in root MSECV at the optimal number of components. Changes in the window size and window number of MWCV do not greatly influence the selection of the number of components. MWCV is demonstrated to be an effective, simple and accurate cross validation method.

Improvement of the partial least squares model performance for oral glucose intake experiments by inside mean centering and inside multiplicative signal correction.

Near infrared (NIR) spectroscopy has become a promising technique for the in vivo monitoring of glucose. Several capillary-rich locations in the body, such as the tongue, forearm, and finger, have been used to collect the in vivo spectra of blood glucose. For such an in vivo determination of blood glucose, collected NIR spectra often show some dependence on the measurement conditions and human body features at the location on which a probe touches. If NIR spectra collected for different oral glucose intake experiments, in which the skin of different patients and the measurement conditions may be quite different, are directly used, partial least squares (PLS) models built by using them would often show a large prediction error because of the differences in the skin of patients and the measurement conditions. In the present study, the NIR spectra in the range of 1300-1900 nm were measured by conveniently touching an optical fiber probe on the forearm skin with a system that was developed for in vivo measurements in our previous work. The spectra were calibrated to resolve the problem derived from the difference of patient skin and the measurement conditions by two proposed methods, inside mean centering and inside multiplicative signal correction (MSC). These two methods are different from the normal mean centering and normal multiplicative signal correction (MSC) that are usually performed to spectra in the calibration set, while inside mean centering and inside MSC are performed to the spectra in every oral glucose intake experiment. With this procedure, spectral variations resulted from the measurement conditions, and human body features will be reduced significantly. More than 3000 NIR spectra were collected during 68 oral glucose intake experiments, and calibrated. The development of PLS calibration models using the spectra show that the prediction errors can be greatly reduced. This is a potential chemometric technique with simplicity, rapidity and efficiency in the pretreatment of NIR spectra collected during oral glucose intake experiments.

Multicomponent spectral correlative chromatography applied to complex herbal medicines.

In this study, a novel chemometric algorithm is presented to facilitate the comparison of relevant chemical components from different herbal samples. This so-called multicomponent spectral correlative chromatography (MSCC) is developed to detect and decide whether two chromatographic clusters are correlated spectrally with each other. The target chromatographic cluster is first partitioned from one herbal spectrochromatogram obtained by hyphenated chromatography. Then, a projection operator is constructed with the principal spectral features extracted from the target to judge the presence or absence of a spectral correlative chromatographic cluster within another herbal spectrochromatogram. For this judgment, congruence coefficient between the original spectral vector and its projected residual is proposed to eliminate the influences from background and noises, especially heteroscedastic noises in the original data. The performance of the MSCC algorithm is demonstrated on both simulated data and real data, and its advantages and disadvantages are also discussed in some detail.

Removal of interference signals due to water from in vivo near-infrared (NIR) spectra of blood glucose by region orthogonal signal correction (ROSC).

A novel chemometric method, region orthogonal signal correction (ROSC), is proposed and applied to pretreat near-infrared (NIR) spectra of blood glucose measured in vivo. Water is the most serious interference component in such kinds of noninvasive measurements, because it shows very high absorbance in the spectra. In the present study, the spectra of blood glucose in the range of 1212 - 1889 nm are used, in which the absorption of water around 1440 nm is very high. ROSC aims at removing the interference signal due to water from the spectra by selecting a set of spectra with a special region of 1404 - 1454 nm that mainly contain information about the variation of the interference component, water, and calculating the orthogonal components to the concentrations of glucose that will be removed. The difference between ROSC and orthogonal signal correction (OSC) is that ROSC uses a special region of spectra for the estimation of scores and loading weights of orthogonal components to pretreat the spectra in other regions, while OSC only uses one fixed region of spectra to calculate loadings, scores and weights of OSC components and removes the OSC components in the same region. A clear advantage of ROSC is that it is more interpretable than OSC, because one can select a spectral region to remove the variation of a special component such as water. Another chemometric method, moving window partial least squares (MWPLSR), is also used to select informative regions of glucose from the NIR spectra of blood glucose measured in vivo, leading to improved PLS models. Results of the application of ROSC demonstrate that ROSC-pretreated spectra including the whole spectral region of 1212 - 1889 nm or an informative region of 1600- 1730 nm selected by MWPLSR provide very good performance of the PLS models. Especially, the later region yields a model with RMSECV of 15.8911 mg/dL for four PLS components. ROSC is a potential chemometric technique in the pretreatment of various spectra.