An erythrocyte membrane-modified biomimetic synergistic nanosystem for cancer anti-vascular therapy and initial efficacy monitoring.

Tumor vascular disruption has become a promising strategy for cancer therapy in recent decades. Nanocomposites loaded with therapeutic materials and drugs are expected to improve the accuracy of anti-vascular therapy and minimize side effects. However, how to prolong blood circulation of therapeutic nanocomposites for enhanced accumulation in tumor vasculature and how to monitor the initial efficacy of anti-vascular therapy for early evaluation of prognosis remain unsolved. Herein, a biomimetic nanosystem consisting of erythrocyte membrane modified nanocomposites (CMNCs) is developed for cooperation to achieve anti-vascular cancer therapy and initial efficacy monitoring. By utilizing poly(lactic-co-glycolic acid) (PLGA) as the interface material, functional nanomaterials and drug molecules are successfully integrated into CMNCs. The long circulation and immune escape features of the erythrocyte membrane facilitate CMNCs loaded with photothermal agents and chemodrugs to be delivered to the tumor region for anti-vascular treatment. Furthermore, the vascular damage-induced haemorrhage and the following coagulation process is labelled by near infrared emissive CMNCs to indicate the initial therapeutic efficacy of the treatment. This work not only points to a biomimetic strategy for conquering the challenges in anti-vascular cancer therapy, but also provides insights into the biological responses of erythrocyte membrane modified nanocomposites to exploit their biomedical applications.

Oral direct thrombin inhibitors or oral factor Xa inhibitors versus conventional anticoagulants for the treatment of deep vein thrombosis.

BACKGROUND: Deep vein thrombosis (DVT) is a condition in which a clot forms in the deep veins, most commonly of the leg. It occurs in approximately one in 1000 people. If left untreated, the clot can travel up to the lungs and cause a potentially life-threatening pulmonary embolism (PE). Previously, a DVT was treated with the anticoagulants heparin and vitamin K antagonists. However, two forms of direct oral anticoagulants (DOACs) have been developed: oral direct thrombin inhibitors (DTIs) and oral factor Xa inhibitors, which have characteristics that may be favourable compared to conventional treatment, including oral administration, a predictable effect, lack of frequent monitoring or dose adjustment and few known drug interactions. DOACs are now commonly being used for treating DVT: recent guidelines recommended DOACs over conventional anticoagulants for both DVT and PE treatment. This Cochrane Review was first published in 2015. It was the first systematic review to measure the effectiveness and safety of these drugs in the treatment of DVT. This is an update of the 2015 review.  OBJECTIVES: To assess the effectiveness and safety of oral DTIs and oral factor Xa inhibitors versus conventional anticoagulants for the long-term treatment of DVT. SEARCH METHODS: The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase and CINAHL databases and the World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to 1 March 2022. SELECTION CRITERIA: We included randomised controlled trials (RCTs) in which people with a DVT, confirmed by standard imaging techniques, were allocated to receive an oral DTI or an oral factor Xa inhibitor compared with conventional anticoagulation or compared with each other for the treatment of DVT.  DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods. Our primary outcomes were recurrent venous thromboembolism (VTE), recurrent DVT and PE. Secondary outcomes included all-cause mortality, major bleeding, post-thrombotic syndrome (PTS) and quality of life (QoL). We used GRADE to assess the certainty of evidence for each outcome. MAIN RESULTS: We identified 10 new studies with 2950 participants for this update. In total, we included 21 RCTs involving 30,895 participants. Three studies investigated oral DTIs (two dabigatran and one ximelagatran), 17 investigated oral factor Xa inhibitors (eight rivaroxaban, five apixaban and four edoxaban) and one three-arm trial investigated both a DTI (dabigatran) and factor Xa inhibitor (rivaroxaban). Overall, the studies were of good methodological quality. Meta-analysis comparing DTIs to conventional anticoagulation showed no clear difference in the rate of recurrent VTE (odds ratio (OR) 1.17, 95% confidence interval (CI) 0.83 to 1.65; 3 studies, 5994 participants; moderate-certainty evidence), recurrent DVT (OR 1.11, 95% CI 0.74 to 1.66; 3 studies, 5994 participants; moderate-certainty evidence), fatal PE (OR 1.32, 95% CI 0.29 to 6.02; 3 studies, 5994 participants; moderate-certainty evidence), non-fatal PE (OR 1.29, 95% CI 0.64 to 2.59; 3 studies, 5994 participants; moderate-certainty evidence) or all-cause mortality (OR 0.66, 95% CI 0.41 to 1.08; 1 study, 2489 participants; moderate-certainty evidence). DTIs reduced the rate of major bleeding (OR 0.58, 95% CI 0.38 to 0.89; 3 studies, 5994 participants; high-certainty evidence).   For oral factor Xa inhibitors compared with conventional anticoagulation, meta-analysis demonstrated no clear difference in recurrent VTE (OR 0.85, 95% CI 0.71 to 1.01; 13 studies, 17,505 participants; moderate-certainty evidence), recurrent DVT (OR 0.70, 95% CI 0.49 to 1.01; 9 studies, 16,439 participants; moderate-certainty evidence), fatal PE (OR 1.18, 95% CI 0.69 to 2.02; 6 studies, 15,082 participants; moderate-certainty evidence), non-fatal PE (OR 0.93, 95% CI 0.68 to 1.27; 7 studies, 15,166 participants; moderate-certainty evidence) or all-cause mortality (OR 0.87, 95% CI 0.67 to 1.14; 9 studies, 10,770 participants; moderate-certainty evidence). Meta-analysis showed a reduced rate of major bleeding with oral factor Xa inhibitors compared with conventional anticoagulation (OR 0.63, 95% CI 0.45 to 0.89; 17 studies, 18,066 participants; high-certainty evidence).  AUTHORS' CONCLUSIONS: The current review suggests that DOACs may be superior to conventional therapy in terms of safety (major bleeding), and are probably equivalent in terms of efficacy. There is probably little or no difference between DOACs and conventional anticoagulation in the prevention of recurrent VTE, recurrent DVT, pulmonary embolism and all-cause mortality. DOACs reduced the rate of major bleeding compared to conventional anticoagulation. The certainty of evidence was moderate or high.

Acupuncture for carpal tunnel syndrome: A systematic review and meta-analysis of randomized controlled trials.

Background: The evidence for the effectiveness of acupuncture for patients with carpal tunnel syndrome (CTS) is insufficient. Therefore, this systematic review and meta-analysis aimed to evaluate the effectiveness of acupuncture on CTS through a comprehensive literature search. Methods: English and Chinese databases were searched from their inceptions until 27 October 2022 to collect randomized controlled trials (RCTs) that investigated the effect of acupuncture on CTS. Two reviewers independently selected studies that met the eligibility criteria, extracted the required data, assessed the risk of bias using version 2 of the Cochrane risk-of-bias tool for randomized trials (ROB 2), and evaluated the quality of reporting for acupuncture interventions using the Revised Standards for Reporting Interventions in Clinical Trials of Acupuncture (STRICTA). The primary outcomes were symptom severity and functional status, while secondary outcomes included pain intensity, responder rate, and electrophysiological parameters. Review Manager software (version 5.4.1) was used for data analysis. The certainty of the evidence was rated with GRADEpro (version 3.6) software. Results: We included 16 RCTs with a total of 1,025 subjects. The overall risk of bias was rated as low in one RCT, some concerns in 14, and high in one. Compared with night splints, acupuncture alone was more effective in relieving pain, but there were no differences in symptom severity and functional status. Acupuncture alone had no advantage over medicine in improving symptom severity and electrophysiological parameters. As an adjunctive treatment, acupuncture might benefit CTS in terms of symptom severity, functional status, pain intensity, and electrophysiological parameters, and it was superior to medicine in improving the above outcomes. Few acupuncture-related adverse events were reported. The above evidence had a low or very low degree of certainty. Conclusion: Acupuncture as an adjunctive treatment may be effective for patients with CTS. Additionally, more rigorous studies with objective outcomes are needed to investigate the effect of acupuncture in contrast with sham acupuncture or other active treatments. Systematic review registration: https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=329925, identifier CRD42022329925.

An Ex Vivo Study of Filum Terminale in Children and Fetuses Based on Optical Coherence Tomography.

Objective: To distinguish ex vivo normal and abnormal filum terminale (FT) in pathology based on optical coherence tomography (OCT). Methods: A total of 14 ex vivo FTs, freshly imaged via OCT after being cut, were excised from the scanned region for histopathological examination (HPE). Qualitative analysis was performed by 2 blinded assessors. Results: We performed OCT imaging of all specimens and validated them qualitatively. In the fetal FTs, we observed large amounts of fibrous tissue scattered throughout with a few capillaries but no adipose tissue. In tight filum terminale syndrome (TFTS), adipose infiltration and capillaries were significantly increased, with obvious fibroplasia and disarrangement. OCT images showed increased adipose tissue in which the adipocytes were arranged in a grid-like pattern; dense, disordered fibrous tissue and vascular-like tissue were present. The diagnostic results of OCT and HPE were consistent (Kappa = 0.659; P = .009, <.01), and there was no statistically significant difference in diagnosing TFTS using a Chi-square test (P > .05). The area under the curve (AUC) for OCT (AUC = 0.966; 95% CI, 0.903 to 1.000) was better than magnetic resonance imaging (MRI) (AUC = 0.649; 95% CI, 0.403 to 0.896). Conclusion: OCT can quickly obtain clear images of FT's inner structure, contribute to diagnosing TFTS and will be an indispensable complement to MRI and HPE. More FT sample studies in vivo are needed to confirm the high accuracy rate of OCT.

Lockdown Social Isolation and Lockdown Stress During the COVID-19 Pandemic in China: The Impact of Mindfulness.

This study is aimed to examine the impact of mindfulness in the relationship between social isolation, job and financial insecurity, and stress during the lockdown period of the COVID-19 pandemic. Drawing on Conservation of Resources theory, Psychological Contract theory, Mindfulness theory, and Awareness notion, we propose that lockdown job insecurity partially mediates the link from lockdown social isolation to lockdown financial insecurity, and that the relationship between lockdown social isolation and lockdown stress is mediated as follows: first, simple partial mediation through both lockdown job and financial insecurity and second, sequential mediation through lockdown job and financial insecurity, respectively. Moreover, we assume that mindfulness moderates the relationship between lockdown financial insecurity and lockdown stress. The results from our SEM analyses, using a sample of 1,356 respondents in China, support all the research hypotheses. Based on this empirical work, this study concludes that mindfulness, which is considered by many people to play a role in reducing stress during the COVID-19 lockdown period, is de facto endangering their mental health (that is, they experience more stress) instead. Theoretical and practical implications, as well as limitations and proposals for future research are discussed.

Label-free SERS strategy for rapid detection of capsaicin for identification of waste oils.

Identification of waste oils is challenging in the field of food safety due to the lack of common markers and straightforward analytical methods. Herein, we developed a novel label-free surface-enhanced Raman spectroscopy (SERS) strategy to identify waste oils using Ag nanoparticles solution (Ag NPs sol.) as a SERS substrate to significantly enhance the Raman signal of capsaicin marker molecule usually contained in the waste oils. The enhanced signal was directly detected by a portable Raman spectrometer with the limit of detection (LOD) of 2.9 µg L-1 within 10 min. Concentration-dependent SERS investigation showed the linear relationship between the SERS signal intensity of the characteristic peaks and the concentrations of capsaicin in the range of 10-2500 µg L-1 and the correlation coefficient was 0.9895. Our findings show the sensitivity, accessibility, and reliability of this method for the rapid identification of waste oils and furthermore for the practical applications in the field of food safety.

Research on Classification of Primary Liver Cancer Syndrome Based on Data Mining Technology.

This study is based on the analysis of the status quo of the research on liver cancer syndromes, starting with the clinical objective and true four-diagnosis information of TCM inpatients with primary liver cancer, using computer data mining technology to analyze and summarize the syndrome rules from the bottom to the top. Let the data itself show the essence of liver cancer syndrome. First, with the help of hierarchical cluster analysis, we can understand the general characteristics through the rough preliminary classification of the four-diagnosis information of liver cancer patients. Then, with the help of the emerging and mature hidden structure model analysis in recent years, through data modeling, the classification of common syndromes of liver cancer and the corresponding relationship with the four-diagnosis information are comprehensively analyzed. Finally, considering the inherent shortcomings of implicit structure and hierarchical clustering based on the assumption that there is a unique one-to-one correspondence between the four diagnostic information factors and the class (or hidden class) when classifying, we plan to use factor analysis and joint cluster analysis, as supplementary means to further explore the classification of liver cancer syndromes and the corresponding relationship with the four-diagnosis information.

Physicochemical properties and structure of modified potato starch granules and their complex with tea polyphenols.

The physicochemical, rheological properties and structure of potato starch and starch-tea polyphenols (TPs) complex modified by enzyme and alcohol was investigated in this study. Cavities on the modified starch granules and morphology change could be investigated by SEM, while significant birefringence observed in complete granules by polarizing light microscope, but disappeared in crashed starch. TPs inhibited the aggregation of amylose and retrogradation of starch-TPs complex, resulting in the decrease of gel strength, and the increase of viscosity and gelatinization stability of starch granules. Fourier transform infrared (FT-IR) spectra showed that intramolecular hydrogen bond could be formed between TPs with modified starch, and the hydrogen bond force formed by starch and TPs was stronger than that between starch molecules. X-ray diffraction (XRD) analysis revealed that three modification methods did not change the crystalline structure of starch, but new diffraction peaks appeared in the four starch-TPs complex, suggesting that the hydrogen bond was incurred by interaction between TPs and amylose to form V-type crystalline. These results demonstrated that the complex formed by TPs and native/modified potato starch could be used in food industrial applications due to the inhibition of starch retrogradation.

l-Phenylalanine Alters the Privileged Secondary Metabolite Production in the Marine-Derived Fungus Trichoderma erinaceum F1-1.

The effects of a single-amino-acid culture strategy on secondary metabolite production in the marine-derived fungus Trichoderma erinaceum F1-1 were investigated by culturing the fungus in GPY medium supplemented or not supplemented with l-phenylalanine. A suite of secondary metabolites, including seven terpenoids (1-7) and one polyketide (8), among which are four new compounds, harziandione A (1), cyclonerodiols A and B (3, 4), and trichodermaerin A (6), were isolated from the GPY medium without l-phenylanine, whereas 18 aromatic compounds (9-26), including six new compounds, trichoderolides A-F (9, 10, and 14-17), were isolated from the culture grown in the GPY medium with l-phenylalanine. The structures of the new compounds were determined by high-resolution mass spectrometry, NMR spectroscopic analysis, optical rotation calculations, chemical methods, and X-ray crystallography. Compounds 10, 12, 13, and 26 exhibited cytotoxic activities against MDA-MB-435 human melanocyte cancer cells. Compound 26 was cytotoxic to A549 adenocarcinomic human alveolar basal epithelial cells.

The anti-oxidation and anti-aging effects of Ganoderma lucidum in Caenorhabditis elegans.

As a traditional herbal medicine, the clinical efficacy of Ganoderma lucidum (G. lucidum, also known as Lingzhi in China) has been proved by clinical research and a large number of animal experiments. However, its pharmacological mechanism is not clear. Here, we used the Caenorhabditis elegans as an animal model to study the anti-oxidative stress and anti-aging effects of G. lucidum water extract. Our results showed that G. lucidum effectively promoted the nematodes to resist the oxidative stress of paraquat and heavy metal Cr6+, and significantly prolonged the lifespan of the nematodes. The underlining mechanisms were further investigated by focusing on the signaling pathways that regulate the stress responses and the lifespan. We found that G. lucidum protected the nematode against the insults of paraquat and heavy metals through the diet restriction pathway and the mTOR/S6K signaling pathway, respectively. Whereas, the effect of G. lucidum on the longevity of the nematode mainly depended on the germline signaling pathway. Microarray assays were conducted to reveal the gene expression profiles. The expression levels of 2746 genes were significantly changed during the aging process, of which 34 genes were reversed in their expression by the treatment of G. lucidum in aged nematodes. These results suggest that G. lucidum regulates the biophysiological processes in the nematodes through multiple signaling pathways.

Fate and wetting potential of bio-refractory organics in membrane distillation for coke wastewater treatment.

Membrane distillation (MD) has been hindered in industrial applications due to the potential wetting or fouling caused by complicated organic compositions. This study investigated the correlations between the fate and wetting potential of bio-refractory organics in the MD process, where three coke wastewater samples pre-treated with bio-degradation and coagulation served as feed solutions. Results showed that although most of the bio-refractory organics in coke wastewater were rejected by the hydrophobic membrane, some volatile aromatic organics including benzenes, phenols, quinolines and naphthalenes passed through the membrane during the MD process. Interestingly, membrane wetting occurred coincidently with the penetration of phenolic and heterocyclic organics. The wetting rate was obviously correlated with the feed composition and membrane surface properties. Ultimately, novel insights into the anti-wetting strategy of MD with bio-refractory organics was proposed, illustrating that the polyaluminum chloride/polyacrylamide coagulation not only removed contaminants which could accelerate membrane wetting, but also retarded membrane wetting by the complexation with organics. The deposition of these complexes on the membrane surface introduced a secondary hydrophilic layer on the hydrophobic substrate, which established a composite membrane structure with superior wetting resistance. These new findings would be beneficial to wetting control in membrane distillation for wastewater treatment.

A potent Cas9-derived gene activator for plant and mammalian cells.

Overexpression of complementary DNA represents the most commonly used gain-of-function approach for interrogating gene functions and for manipulating biological traits. However, this approach is challenging and inefficient for multigene expression due to increased labour for cloning, limited vector capacity, requirement of multiple promoters and terminators, and variable transgene expression levels. Synthetic transcriptional activators provide a promising alternative strategy for gene activation by tethering an autonomous transcription activation domain (TAD) to an intended gene promoter at the endogenous genomic locus through a programmable DNA-binding module. Among the known custom DNA-binding modules, the nuclease-dead Streptococcus pyogenes Cas9 (dCas9) protein, which recognizes a specific DNA target through base pairing between a synthetic guide RNA and DNA, outperforms zinc-finger proteins and transcription activator-like effectors, both of which target through protein-DNA interactions 1 . Recently, three potent dCas9-based transcriptional activation systems, namely VPR, SAM and SunTag, have been developed for animal cells 2-6 . However, an efficient dCas9-based transcriptional activation platform is still lacking for plant cells 7-9 . Here, we developed a new potent dCas9-TAD, named dCas9-TV, through plant cell-based screens. dCas9-TV confers far stronger transcriptional activation of single or multiple target genes than the routinely used dCas9-VP64 activator in both plant and mammalian cells.

Dietary Fiber Intake Regulates Intestinal Microflora and Inhibits Ovalbumin-Induced Allergic Airway Inflammation in a Mouse Model.

BACKGROUND: Recently, academic studies suggest that global growth of airway allergic disease has a close association with dietary changes including reduced consumption of fiber. Therefore, appropriate dietary fiber supplementation might be potential to prevent airway allergic disease (AAD). OBJECTIVE: We investigated whether dietary fiber intake suppressed the induction of AAD and tried to elucidate the possible underlying mechanisms. METHODS: The control mice and AAD model mice fed with 4% standard-fiber chow, while low-fiber group of mice fed with a 1.75% low-fiber chow. The two fiber-intervened groups including mice, apart from a standard-fiber diet, were also intragastric (i.g.) administrated daily with poorly fermentable cellulose or readily fermentable pectin (0.4% of daily body weight), respectively. All animals except normal mice were sensitized and challenged with ovalbumin (OVA) to induce airway allergic inflammation. Hallmarks of AAD were examined by histological analysis and ELISA. The variation in intestinal bacterial composition was assessed by qualitative analysis of 16S ribosomal DNA (rDNA) content in fecal samples using real-time PCR. RESULTS: Low-fiber diet aggravated inflammatory response in ovalbumin-induced allergic mice, whereas dietary fiber intake significantly suppressed the allergic responses, attenuated allergic symptoms of nasal rubbing and sneezing, decreased the pathology of eosinophil infiltration and goblet cell metaplasia in the nasal mucosa and lung, inhibited serum OVA-specific IgE levels, and lowered the levels of Th2 cytokines in NALF and BALF, but, increased Th1 (IFN-γ) cytokines. Additionally, dietary fiber intake also increased the proportion of Bacteroidetes and Actinobacteria, and decreased Firmicutes and Proteobacteria. Levels of probiotic bacteria, such as Lactobacillus and Bifidobacterium, were upgraded significantly. CONCLUSION: Long-term deficiency of dietary fiber intake increases the susceptibility to AAD, whereas proper fiber supplementation promotes effectively the balance of Th1/Th2 immunity and then attenuates allergic inflammatory responses significantly, as well as optimizes the structure of intestinal microbiota, which suggests potential for novel preventive and therapeutic intervention.

Selenium-containing naphthalimides as anticancer agents: design, synthesis and bioactivity.

Selenium analogues (4b-4h, and 4j) of two known sulfur compounds were synthesized and tested their anticancer activities. The selenium compound 4b had comparable activity with its sulfur analogue 4a, while DNA-binding study showed these two compounds had similar interaction with ct-DNA, the K(b) was 8.23 and 2.36, respectively. The primary results showed that most compounds had moderate anticancer activities with IC(50) values between 10(-6) and 10(-5) M. Another selenium analogue 4j showed the highest activity with the IC(50) values around 5.3 µM against K562 and MCF-7 cell lines. More importantly, the organochalcogen compounds exhibited stronger anticancer activities against K562 cell line than the other cell lines tested.

Catalytic oxidation of elemental mercury over the modified catalyst Mn/alpha-Al2O3 at lower temperatures.

In order to facilitate the removal of elemental mercury (Hg(0)) from coal-fired flue gas, catalytic oxidation of Hg(0) with manganese oxides supported on inert alumina (alpha-Al2O3) was investigated at lower temperatures (373-473 K). To improve the catalytic activity and the sulfur-tolerance of the catalysts at lower temperatures, several metal elements were employed as dopants to modify the catalyst of Mn/alpha-Al2O3. The best performance among the tested elements was achieved with molybdenum (Mo) as the dopant in the catalysts. It can work even better than the noble metal catalyst Pd/alpha-Al2O3. Additionally, the Mo doped catalyst displayed excellent sulfur-tolerance performance at lower temperatures, and the catalytic oxidation efficiency for Mo(0.03)-Mn/alpha-Al2O3 was over 95% in the presence of 500 ppm SO2 versus only about 48% for the unmodified catalyst. The apparent catalytic reaction rate constant increased by approximately 5.5 times at 423 K. In addition, the possible mechanisms involved in Hg(0) oxidation and the reaction with the Mo modified catalyst have been discussed.

Varietal characterization of hop (Humulus lupulus L.) by GC-MS analysis of hop cone extracts.

An approach is described for use in the varietal characterization of hop (Humulus lupulus L.) varieties. The study focuses on commercial hop varieties and was timed to coincide with the 2008 commercial hop harvest in Tasmania, Australia. Analysis of hop extracts was performed using GC-MS. A 60 m capillary column was employed to increase efficiency to permit the use of a quadrupole mass spectrometer in place of a time of flight mass spectrometer that is more commonly used for this type of analysis. A set of characterization functions were derived from discriminant analysis which were highly suitable for varietal characterization of the eight commercial varieties included in the study, namely Willamette, Victoria, Pride of Ringwood, Cascade, Southern Hallertau, Millennium, Southern Saaz, and Super Pride.

Classification of weathered petroleum oils by multi-way analysis of gas chromatography-mass spectrometry data using PARAFAC2 parallel factor analysis.

The application of multi-way parallel factor analysis (PARAFAC2) is described for the classification of different kinds of petroleum oils using GC-MS. Oils were subjected to controlled weathering for 2, 7 and 15 days and PARAFAC2 was applied to the three-way GC-MS data set (MSxGCxsample). The classification patterns visualized in scores plots and it was shown that fitting multi-way PARAFAC2 model to the natural three-way structure of GC-MS data can lead to the successful classification of weathered oils. The shift of chromatographic peaks was tackled using the specific structure of the PARAFAC2 model. A new preprocessing of spectra followed by a novel use of analysis of variance (ANOVA)-least significant difference (LSD) variable selection method were proposed as a supervised pattern recognition tool to improve classification among the highly similar diesel oils. This lead to the identification of diagnostic compounds in the studied diesel oil samples.

Numerical methods for comparing fresh and weathered oils by their FTIR spectra.

Four comparison statistics ('similarity indices') for the identification of the source of a petroleum oil spill based on the ASTM standard test method D3414 were investigated. Namely, (1) first difference correlation coefficient squared and (2) correlation coefficient squared, (3) first difference Euclidean cosine squared and (4) Euclidean cosine squared. For numerical comparison, an FTIR spectrum is divided into three regions, described as: fingerprint (900-700 cm(-1)), generic (1350-900 cm(-1)) and supplementary (1770-1685 cm(-1)), which are the same as the three major regions recommended by the ASTM standard. For fresh oil samples, each similarity index was able to distinguish between replicate independent spectra of the same sample and between different samples. In general, the two first difference-based indices worked better than their parent indices. To provide samples to reveal relationships between weathered and fresh oils, a simple artificial weathering procedure was carried out. Euclidean cosine and correlation coefficients both worked well to maintain identification of a match in the fingerprint region and the two first difference indices were better in the generic region. Receiver operating characteristic curves (true positive rate versus false positive rate) for decisions on matching using the fingerprint region showed two samples could be matched when the difference in weathering time was up to 7 days. Beyond this time the true positive rate falls and samples cannot be reliably matched. However, artificial weathering of a fresh source sample can aid the matching of a weathered sample to its real source from a pool of very similar candidates.