Serum 25-hydroxyvitamin D concentrations, vitamin D receptor polymorphisms, and risk of infections among individuals with type 2 diabetes: a prospective cohort study.

BACKGROUND: Evidence on the association between serum 25-hydroxyvitamin D [25(OH)D] and infections among patients with type 2 diabetes (T2D), a group susceptible to vitamin D deficiency and infections, is limited. OBJECTIVES: We aimed to examine this association in individuals with T2D, and to evaluate whether genetic variants in vitamin D receptor (VDR) would modify this association. METHODS: This study included 19,851 participants with T2D from UK Biobank. Infections were identified by linkage to hospital inpatient and death registers. Negative binomial regression models were used to estimate incidence rate ratios (IRRs) and 95% confidence intervals (CIs), with adjustment of potential confounders. RESULTS: In patients with T2D, the incidence rate of infections was 29.3/1000 person-years. Compared to those with 25(OH)D of 50.0-74.9 nmol/L, the multivariable-adjusted IRRs and 95% CIs of total infections, pneumonia, gastrointestinal infections and sepsis were 1.44 (1.31, 1.59), 1.49 (1.27, 1.75), 1.47 (1.22, 1.78), and 1.41 (1.14, 1.73), respectively, in patients with 25(OH)D <25.0 nmol/L. Nonlinear inverse associations between 25(OH)D concentrations and the risks of total infections (P-overall <0.001; P-nonlinear = 0.002) and gastrointestinal infections (P-overall <0.001; P-nonlinear = 0.040) were observed, with a threshold effect at ∼50.0 nmol/L. The vitamin D-infection association was not modified by genetic variants in VDR (all P-interaction >0.050). CONCLUSIONS: In patients with T2D, lower serum 25(OH)D concentration (<50 nmol/L) was associated with higher risks of infections, regardless of genetic variants in VDR. Notably, nonlinear inverse associations between 25(OH)D concentrations and the risks of infections were found, with a threshold effect at ∼50.0 nmol/L. These findings highlighted the importance of maintaining adequate vitamin D in reducing the risk of infections in patients with T2D.

Associations Between Beverage Consumption and Risk of Microvascular Complications Among Individuals With Type 2 Diabetes.

CONTEXT: The relationship between the consumption of different beverages and the risk of microvascular complications in individuals with type 2 diabetes (T2D) is unclear. OBJECTIVE: To investigate the association of individual beverage consumption, including artificially sweetened beverages (ASBs), sugar-sweetened beverages (SSBs), tea, coffee, natural juice, and yogurt, with the risk of microvascular complications in adults with T2D. METHODS: This cohort study included 6676 participants with T2D who were free of macrovascular and microvascular complications at baseline in the UK Biobank. Cox proportional hazard models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs). RESULTS: During a median follow-up of 11.7 years, 1116 cases of composite microvascular complications were documented. After multivariable adjustment, a linear dose-response relationship was demonstrated between the consumption of ASBs and SSBs and the risk of microvascular complications. Compared with nonconsumers, those who consumed ≥2.0 units/day of ASBs and SSBs had an HR (95% CI) of 1.44 (1.18-1.75) and 1.32 (1.00-1.76) for composite microvascular complications, respectively. In addition, higher tea consumption was associated with a lower risk of diabetic retinopathy, with an HR (95% CI) of 0.72 (0.57-0.92) for whom consuming ≥4.0 units/day. There was no significant association between individual beverage consumption and the risk of diabetic neuropathy. No significant association was observed between the consumption of coffee, natural juice, or yogurt and the risks of microvascular complications. Moreover, substituting half units/day of ASBs or SSBs with tea or coffee was associated with a 16% to 28% lower risk of microvascular complications. CONCLUSION: Higher consumption of ASBs and SSBs was linearly associated with an increased risk of microvascular complications in adults with T2D.

Associations of serum 25-hydroxyvitamin D and vitamin D receptor polymorphisms with risks of cardiovascular disease and mortality among patients with chronic kidney disease: a prospective study.

BACKGROUND: Evidence regarding the relationships of serum 25-hydroxyvitamin D [25(OH)D] with cardiovascular diseases (CVD) and mortality among patients with chronic kidney disease (CKD) is limited and inconsistent. OBJECTIVES: This study aimed to investigate the associations between serum 25(OH)D and CVD incidence and mortality among patients with CKD. METHODS: This prospective study included 21,507 participants with CKD and free of CVD in the UK Biobank. Incidences of total and subtypes of CVD and mortality were ascertained via electronic health records. Cox proportional hazard regression models were used to estimate the hazard ratios (HRs) and 95% confidential intervals (CIs) for CVD incidence and mortality. RESULTS: The median serum 25(OH)D concentration was 44.0 nmol/L (interquartile range: 30.1, 60.6 nmol/L). After multivariable adjustment, compared with CKD patients with serum 25(OH)D concentrations of <25 nmol/L, those with serum 25(OH)D ≥75 nmol/L had HRs (95% CIs) of 0.80 (0.71, 0.90) for total CVD incidence, 0.82 (0.69, 0.97) for ischemic heart disease, 0.56 (0.41, 0.77) for stroke, 0.64 (0.46, 0.88) for myocardial infarction, 0.62 (0.49, 0.80) for heart failure, 0.60 (0.43, 0.85) for CVD mortality, and 0.62 (0.52, 0.74) for all-cause mortality. In addition, these associations were not modified by vitamin D receptor polymorphisms, with no significant interaction detected. CONCLUSIONS: Higher serum 25(OH)D concentrations were significantly associated with lower risks of total and subtypes of CVD incidence and mortality among individuals with CKD. These findings highlight the importance of maintaining adequate vitamin D status in the prevention of CVD and mortality in patients with CKD.

Modifiable Lifestyle Factors, Genetic Risk, and Incident Peripheral Artery Disease Among Individuals With Type 2 Diabetes: A Prospective Study.

OBJECTIVE: To prospectively evaluate the association between modifiable lifestyle factors and peripheral artery disease (PAD) among individuals with type 2 diabetes (T2D). RESEARCH DESIGN AND METHODS: We included 14,543 individuals with T2D from the UK Biobank. We defined a weighted healthy lifestyle score using nonsmoking, regular physical activity, high-quality diet, moderate alcohol consumption, optimal waist-to-hip ratio, and adequate sleep duration, and categorized into unfavorable, intermediate, and favorable lifestyles. We created a genetic risk score (GRS) using 19 single nucleotide polymorphisms previously found to be associated with PAD. We modeled the association between lifestyle score and PAD, overall and stratified by PAD genetic susceptibility. RESULTS: After a median 13.5 years of follow-up, 628 incident cases of PAD were documented. A linear inverse association between the weighted lifestyle score and PAD was observed, with a hazard ratio (HR) (95% CI) of 0.27 (0.19, 0.38) for favorable compared with unfavorable lifestyle (Ptrend < 0.0001). An estimated 58.3% (45.0%, 69.1%) of PAD in this population could be potentially avoidable if all participants attained a favorable lifestyle. Moreover, the PAD GRS was associated with increased PAD risk (HR [95% CI] per SD increment: 1.13 [1.03, 1.23]). A favorable lifestyle was able to partially mitigate the excess risk of PAD associated with higher GRS, albeit as a nonsignificant interaction. Several biomarkers in the lipid metabolism, hepatic/renal function, and systemic inflammation pathways collectively explained 13.3% (8.5%, 20.1%) of the association between weighted lifestyle score and PAD. CONCLUSIONS: A favorable lifestyle was associated with lower risk of PAD among individuals with T2D, independent of genetic predisposition to PAD.

APOE Genotype Modifies the Association between Midlife Adherence to the Planetary Healthy Diet and Cognitive Function in Later Life among Chinese Adults in Singapore.

BACKGROUND: It remains unclear if adherence to the planetary healthy diet (PHD), designed to improve human and environmental health, is associated with better cognitive function in aging, and if this association differs by apolipoprotein E (APOE) genotype. OBJECTIVES: We aimed to examine the association between the PHD pattern and risk of poor cognitive function, and to further assess whether the APOE ε4 allele could modify this association. METHODS: The study included 16,736 participants from the Singapore Chinese Health Study. The PHD score was calculated using data from a validated 165-item food frequency questionnaire at baseline (1993-1998), with higher scores indicating greater adherence to the PHD. Cognitive function was assessed by the Singapore-modified Mini-Mental State Examination at follow-up 3 visits (2014-2016). A subset of 9313 participants had APOE genotype data. Logistic regression models were used to estimate the odds ratios (ORs) and 95% confidence intervals (CIs), with adjustment for potential confounders. RESULTS: We identified 2397 (14.3%) cases of poor cognitive function. In the total population, OR (95% CI) of poor cognitive function for each one-SD increment in the PHD score was 0.89 (0.85, 0.93). Carriers of APOE ε4 allele had increased risk of poor cognitive function (OR: 1.36, 95% CI: 1.15, 1.61). There was a significant interaction between the PHD score and the APOE ε4 allele (P-interaction = 0.042). Each one-SD increment in the PHD score was significantly associated with lower risk of poor cognitive function (OR: 0.89; 95% CI: 0.83, 0.96) in non-carriers of APOE ε4 allele, but not in APOE ε4 allele carriers (OR: 1.04, 95% CI: 0.89, 1.23). CONCLUSIONS: Midlife adherence to the PHD was associated with reduced risk of poor cognitive function in later life. However, this was not observed in carriers of APOE ε4 allele who had higher risk of poor cognitive function.

Incidence density of hyperuricemia and association between metabolism-related predisposing risk factors and serum urate in Chinese adults: a cohort study.

Background: Evidence regarding the association between metabolism-related indicators and serum urate (SU) is limited. We aimed to obtain the incidence density of hyperuricemia and to explore the association between metabolism-related predisposing risk factors and SU. Methods: A total of 48,979 Chinese adults from the Beijing Physical Examination Center were included in the study. The partial least squares path model was used to explore the relationship between SU and metabolism-related risk factors. The generalized additive model was used for smooth curve fitting, showing the sex-specific associations of SU at follow-up with baseline fasting blood glucose (FBG) concentrations and age. Results: The incidence density of hyperuricemia was 78/1000 person-years. Baseline SU, age, sex, obesity, FBG, and lipid metabolism were significantly associated with SU at follow-up (all P values <0.05). Non-linear relationships were found between the baseline FBG concentrations and SU at follow-up, while U-shaped associations were observed between baseline age and SU at follow-up. Conclusions: The SU concentration is associated with several metabolism-related risk factors such as obesity and FBG. Recognition of these associations will aid in a deeper understanding of the multifaceted nature of SU regulation.

Dose-Response Meta-Analysis on Risk of Diabetes in Relation to Red and Processed Meat Consumption - Asian Populations, 2006-2021.

What is already known about this topic?: Red and processed meat consumption has been positively related to an increased risk of diabetes in Western populations. However, the results remain inconclusive within Asian populations. What is added by this report?: This dose-response meta-analysis of prospective cohort studies conducted in East Asian populations reveals a positive relation between the consumption of processed meat and increased risk of diabetes. Furthermore, a U-shaped association was identified between the consumption of unprocessed red meat and the risk of diabetes. What are the implications for public health practice?: This research presents substantive evidence advocating for the reduction of processed and unprocessed red meat consumption as a viable strategy for mitigating the risk of diabetes in East Asian populations.

Trends in Self-Reported Adherence to Healthy Lifestyle Behaviors Among US Adults, 1999 to March 2020.

Importance: Adherence to a healthy lifestyle is associated with lower risks of adverse outcomes. However, trends in multiple lifestyle factors and overall healthy lifestyle status among US adults in recent years are unknown. Objective: To examine trends in multiple lifestyle factors and overall healthy lifestyle among US adults. Design, Setting, and Participants: This serial cross-sectional study used nationally representative data from 10 National Health and Nutrition Examination Survey (NHANES) cycles (nine 2-year cycles from 1999 to 2016 and 1 combined cycle from 2017 to March 2020) among adults 20 years or older. Data were analyzed from December 10, 2021, to January 11, 2023. Exposure: Survey cycle. Main Outcomes and Measures: Five healthy lifestyle factors: never smoking, moderate or lighter alcohol consumption (for women: ≤7 drinks/wk; for men: ≤14 drinks/wk), healthy diet (Healthy Eating Index-2015 scores ≥60.0), sufficient physical activity (≥150 min/wk of equivalent moderate physical activity), and healthy weight (body mass index [calculated as weight in kilograms divided by height in meters squared] 18.5-24.9). Results: A total of 47 852 adults were included in this study. The weighted mean [SE] age was 47.3 [0.2] years; 24 539 (weighted proportion, 51.5%) were women. From the 1999-2000 cycle to the 2017 to March 2020 cycle, the estimated prevalence of the 5 lifestyle factors showed divergent trends, with increasing prevalence of never smoking (from 49.4% [95% CI, 46.4%-52.4%] to 57.7% [95% CI, 55.5%-59.9%]; difference, 8.2% [95% CI, 4.5%-12.0%]), healthy diet (from 19.3% [95% CI, 16.0%-22.6%] to 24.5% [95% CI, 21.5%-27.5%]; difference, 5.2% [95% CI, 0.8%-9.7%]), and sufficient physical activity (from 55.7% [95% CI, 51.8%-59.6%] to 69.1% [95% CI, 67.2%-71.1%]; difference, 13.4% [95% CI, 9.0%-17.8%]), while prevalence of healthy weight decreased from 33.1% (95% CI, 30.5%-35.6%) to 24.6% (95% CI, 22.6%-26.7%; difference, -8.4% [95% CI, -11.8% to -5.1%]) (all P < .001 for trend). Meanwhile, there was no significant trend in moderate or lighter alcohol consumption. Overall, the estimated prevalence of at least 4 healthy lifestyle factors increased from 15.7% (95% CI, 12.8%-18.7%) to 20.3% (95% CI, 17.8%-22.7%; difference, 4.5% [95% CI, 0.7%-8.4%]; P < .001 for trend). Disparities in healthy lifestyle were widened by age group, with little improvement among adults 65 years and older (difference, 0.04% [95% CI, -4.28% to 4.35%]). There were persistent disparities in healthy lifestyle by race and ethnicity, educational level, and income level. Conclusions and Relevance: The findings of this cross-sectional study of NHANES data over a 22-year period suggest diverse change patterns across 5 healthy lifestyle factors and a modest improvement in overall lifestyle existed among US adults, with worsening or persistent disparities in lifestyle.

Comparing recombinant human rabies monoclonal antibody (ormutivimab) with human rabies immunoglobulin (HRIG) for postexposure prophylaxis: A phase III, randomized, double-blind, non-inferiority trial.

OBJECTIVES: To evaluate the immunogenicity and safety of an anti-rabies monoclonal antibody (mAb), ormutivimab, compared with human rabies immunoglobulin (HRIG). METHODS: This phase III trial was designed as a randomized, double-blind, non-inferiority clinical trial in patients aged ≥18 years with suspected World Health Organization category Ⅲ rabies exposure. The participants were randomized 1:1 to ormutivimab and HRIG groups. After thorough wound washing and injection of ormutivimab/HRIG on day 0, the vaccination was administered on days 0, 3, 7, 14, and 28. The primary endpoint was the adjusted geometric mean concentration (GMC) of rabies virus-neutralizing activity (RVNA) on day 7. The endpoint of safety included the occurrence of adverse reactions and serious adverse events. RESULTS: A total of 720 participants were recruited. The adjusted-GMC of RVNA (0.41 IU/ml) on day 7 in ormutivimab group was not inferior to that in the HRIG group (0.41 IU/ml), with ratio of adjusted-GMC of 1.01 (95% confidence interval: 0.91, 1.14). The seroconversion rate of the ormutivimab group was higher than that of the HRIG group on days 7, 14, and 42. Most local injection sites and systemic adverse reactions reported from both groups were mild to moderate in severity. CONCLUSION: ormutivimab + vaccine can protect victims aged ≥18 years with category Ⅲ suspected rabies exposure as a component of postexposure prophylaxis. ormutivimab has a weaker influence on the immunity response of rabies vaccines. CLINICAL TRIALS REGISTRATION: ChiCTR1900021478 (the Chinese Clinical Trial Registry of World Health Organization).

Conjugated dual size effect of core-shell particles synergizes bimetallic catalysis.

Core-shell bimetallic nanocatalysts have attracted long-standing attention in heterogeneous catalysis. Tailoring both the core size and shell thickness to the dedicated geometrical and electronic properties for high catalytic reactivity is important but challenging. Here, taking Au@Pd core-shell catalysts as an example, we disclose by theory that a large size of Au core with a two monolayer of Pd shell is vital to eliminate undesired lattice contractions and ligand destabilizations for optimum benzyl alcohol adsorption. A set of Au@Pd/SiO2 catalysts with various core sizes and shell thicknesses are precisely fabricated. In the benzyl alcohol oxidation reaction, we find that the activity increases monotonically with the core size but varies nonmontonically with the shell thickness, where a record-high activity is achieved on a Au@Pd catalyst with a large core size of 6.8 nm and a shell thickness of ~2-3 monolayers. These findings highlight the conjugated dual particle size effect in bimetallic catalysis.

Association between serum 25-hydroxy vitamin D concentrations and mortality among individuals with metabolic dysfunction-associated fatty liver disease: a prospective cohort study.

BACKGROUND: The association between serum 25-hydroxyvitamin D [25(OH)D] concentrations and mortality among patients with metabolic dysfunction-associated fatty liver disease (MAFLD) or nonalcoholic fatty liver disease (NAFLD) remains unclear. OBJECTIVE: The aim was to evaluate the association between serum 25(OH)D concentrations and mortality among individuals with MAFLD/NAFLD. METHODS: The study included 4651 individuals with fatty liver disease (FLD; 3964 had MAFLD and 3968 had NAFLD) from NHANES III. Fatty liver disease was identified by ultrasonographic detection of hepatic steatosis. Mortality was ascertained by linkage to the National Death Index up to 31 December 2019. Cox proportional hazards models were used to estimate the HRs and 95% CIs, with adjustment of potential confounders. RESULTS: Of 4651 individuals with FLD, 3427 individuals (69.7%) had both MAFLD and NAFLD. During median follow-ups of 25.8 and 26.1 y, we identified 1809 and 1665 deaths among 3964 participants with MAFLD and 3968 participants with NAFLD, respectively. Compared with participants with serum 25(OH)D concentrations ≤30.0 nmol/L, the multivariable-adjusted HRs and 95% CIs of all-cause mortality were 0.62 (0.43, 0.89) for participants with MAFLD having serum 25(OH)D >75.0 nmol/L (P-trend = 0.001) and 0.63 (0.42, 0.95) for participants with NAFLD having serum 25(OH)D >75.0 nmol/L (P-trend = 0.002). A nonlinear inverse association was observed between serum 25(OH)D concentrations and all-cause mortality among participants with MAFLD (Poverall < 0.001; Pnonlinear = 0.003) or NAFLD (Poverall < 0.001; Pnonlinear = 0.009), with a threshold effect at ∼50.0 nmol/L. The inverse association was stronger among participants with MAFLD aged <60 y (P-interaction = 0.001). CONCLUSIONS: This study suggested a nonlinear inverse association between serum 25(OH)D concentrations and all-cause mortality among patients with MAFLD/NAFLD, with a threshold effect at ∼50.0 nmol/L of serum 25(OH)D.

Long-term glycemic variability and risk of adverse health outcomes in patients with diabetes: A systematic review and meta-analysis of cohort studies.

AIMS: To quantify associations of different metrics of long-term glycemic variability (GV) with multiple adverse diabetes-related outcomes. METHODS: We searched PubMed and Embase from database inception to 23 August 2021. GV was based on measurements of HbA1c or fasting plasma glucose (FPG) and calculated by standard deviation (SD), coefficient of variance (CV) or other metrics. Outcomes included mortality, cardiovascular disease (CVD), renal disease, peripheral neuropathy, retinopathy, dementia and cancer. Random-effects meta-analyses were adopted to pool the relative risks (RRs). RESULTS: Seventy-five articles with 2,051,701 participants were included. When comparing top with bottom quartiles, HbA1c variabilities were associated with all-cause mortality (RRCV = 1.63, 95 % CI 1.37-1.92; RRSD = 1.87, 1.55-2.26), CVD (RRCV = 1.38, 1.07-1.78; RRSD = 1.34, 1.12-1.59), renal disease (RRCV = 1.43, 1.18-1.74; RRSD = 1.44, 1.24-1.67), and peripheral neuropathy (RRCV = 1.84, 1.40-2.43; RRSD = 1.98, 1.51-2.61), but not retinopathy. FPG variabilities were associated with all-cause mortality (RRCV = 1.59, 1.43-1.78; RRSD = 1.67, 1.26-2.20), renal disease (RRCV = 1.77, 1.32-2.38), and retinopathy (RRCV = 1.92, 1.10-3.35), but not CVD and peripheral neuropathy. Associations of GV with Alzheimer's disease (RRHbA1c-CV = 1.38, 1.13-1.70; RRFPG-CV = 1.32, 1.07-1.63) and cancer (RRHbA1c-SD = 2.19, 1.52-3.17; RRFPG-CV = 3.64, 2.21-5.98) were each found significant in one study. CONCLUSIONS: Long-term GV was associated with multiple adverse diabetes-related outcomes, while the strength of associations varied. The findings support the use of long-term GV for diabetes management in clinical practice.

Importance of ideal cardiovascular health metrics in the risk of colorectal cancer among people aged 50 years or older: a UK Biobank cohort study.

OBJECTIVE: To explore the correlation between the ideal cardiovascular health metrics (ICVHMs) and the incidence of colorectal cancer (CRC) among people aged 50 years or older. DESIGN: Prospective cohort study. SETTING: The UK Biobank, a prospective cohort of middle-aged participants recruited between 2006 and 2010. PARTICIPANTS: The study included 342 226 participants from the UK Biobank aged 50 years or older without prevalent cancer. EXPOSURE: The ICVHMs consist of four behavioural factors (abstinence from smoking, ideal body mass index (BMI), physical activity at goal and consumption of healthy diet) and three cardiometabolic factors (untreated total cholesterol <200 mg/dL, untreated blood pressure <120/80 mm Hg and untreated fasting plasma glucose <100 mg/dL). MAIN OUTCOMES: The outcome was ascertained by linkage to cancer and death registries using the International Classification of Diseases, Tenth codes C18-C20. RESULTS: During a median follow-up time of 8.72 years, 3060 CRC cases were identified. Compared with the reference (participants with ICVHMs ≤2), the multivariable-adjusted HRs for subgroups with 3, 4, 5 and ≥6 ICVHM factors were 0.98 (95% CI 0.85 to 1.12), 0.90 (95% CI 0.77 to 1.02), 0.85 (95% CI 0.71 to 0.98) and 0.69 (95% CI 0.48 to 0.90), respectively. Among the seven ICVHM factors, lower BMI, healthier diet and ideal fasting plasma glucose were significantly associated with lower risk of CRC (HR: 0.86, 95% CI 0.78 to 0.95; HR: 0.92, 95% CI 0.84 to 0.99; HR: 0.90, 95% CI 0.80 to 0.99). CONCLUSIONS: Adherence to the ICVHMs was associated with a lower risk of CRC among people aged 50 years or older. Among the seven ICVHM factors, BMI, diet and fasting plasma glucose played a more critical role in the prevention of CRC. These findings imply that adherence to ICVHMs should be encouraged to reduce the burden of cardiovascular disease as well as CRC.

The evolution of spectral intensity and orbital angular momentum of twisted Hermite Gaussian Schell model beams in turbulence.

We introduce a new class of twisted partially coherent beams with a non-uniform correlation structure. These beams, called twisted Hermite Gaussian Schell model (THGSM) beams, have a correlation structure related to Hermite functions and a twist factor in their degree of coherence. The spectral density and total average orbital angular momentum per photon of these beams strongly depend on the distortions applied to their degree of coherence. On propagation through free space, they exhibit both self-splitting and rotation of their spectral density profile, combining the interesting effects of twisted beams and non-uniformly correlated beams. We demonstrate that we can adjust both the beam order and the twist factor of THGSM beams to improve their resistance to turbulence.

Vision-based technique for circle detection and measurement using lookup table and bitwise center accumulator.

In this paper, we proposed a fast algorithm for circle detection and measurement, which uses a lookup table and bitwise center accumulator (LUT-BCA). The LUT-BCA is a two-stage procedure. The first stage determines the candidate circle centers with normal lines produced by the lookup table and recorded by the bitwise center accumulator. The second stage computes the radius of each candidate circle center and validates these centers, which eliminates the false detections. The proposed LUT-BCA can also be easily implemented on massively parallel high-performance graphics hardware using the compute unified device architecture. Experimental results indicate that the LUT-BCA can locate circle centers and measure their radii accurately and is very suitable for real-time circle detection and measurement.

Probability-based non-local means filter for speckle noise suppression in optical coherence tomography images.

In this Letter, a probability-based non-local means filter is proposed for speckle reduction in optical coherence tomography (OCT). Originally developed for additive white Gaussian noise, the non-local means filter is not suitable for multiplicative speckle noise suppression. This Letter presents a two-stage non-local means algorithm using the uncorrupted probability of each pixel to effectively reduce speckle noise in OCT. Experiments on real OCT images demonstrate that the proposed filter is competitive with other state-of-the-art speckle removal techniques and able to accurately preserve edges and structural details with small computational cost.

Image denoising using trivariate shrinkage filter in the wavelet domain and joint bilateral filter in the spatial domain.

This correspondence proposes an efficient algorithm for removing Gaussian noise from corrupted image by incorporating a wavelet-based trivariate shrinkage filter with a spatial-based joint bilateral filter. In the wavelet domain, the wavelet coefficients are modeled as trivariate Gaussian distribution, taking into account the statistical dependencies among intrascale wavelet coefficients, and then a trivariate shrinkage filter is derived by using the maximum a posteriori (MAP) estimator. Although wavelet-based methods are efficient in image denoising, they are prone to producing salient artifacts such as low-frequency noise and edge ringing which relate to the structure of the underlying wavelet. On the other hand, most spatial-based algorithms output much higher quality denoising image with less artifacts. However, they are usually too computationally demanding. In order to reduce the computational cost, we develop an efficient joint bilateral filter by using the wavelet denoising result rather than directly processing the noisy image in the spatial domain. This filter could suppress the noise while preserve image details with small computational cost. Extension to color image denoising is also presented. We compare our denoising algorithm with other denoising techniques in terms of PSNR and visual quality. The experimental results indicate that our algorithm is competitive with other denoising techniques.

DNA-binding and photocleavage properties of cationic porphyrin-anthraquinone hybrids with different lengths of links.

Four cationic porphyrin-anthraquinone (Por-AQ) hybrids differing in lengths of flexible alkyl linkage, 5-[4-(1-N-anthraquinonon-yl)-L-oxophenyl]-10,15,20-tris(N-methylpyridinium-4-yl)porphyrin triiodide, (L = acetyl, pentanoyl, octanoyl, undecanoyl, designed as [AQATMPyP]I3, [AQPTMPyP]I3, [AQOTMPyP]I3 and [AQUTMPyP]I3, respectively, see Fig. 1), were synthesized and their interactions with DNA were investigated. The results of spectroscopic, denaturation and viscosity measurements suggest that [AQATMPyP]I3 binds to DNA through non-intercalative mode while the other three hybrids with longer links bind via bis-intercalative mode. Ethidium bromide (EB) competition experiment was carried out to determine the binding constants (Kb) of these compounds for CT DNA, and [AQPTMPyP]I3 shows the largest Kb among these hybrids. The photocleavage mechanism and wavelength-dependent cleaving abilities of these hybrids to pBR322 plasmid DNA were also comparably investigated.

Tricationic pyridium porphyrins appending different peripheral substituents: experimental and DFT studies on their interactions with DNA.

Four tricationic pyridium porphyrins appending hydroxyphenyl, methoxyphenyl, propionoxyphenyl or carboxyphenyl group at meso-20-position of porphyrin core have been synthesized and their abilities to bind and cleave DNA have been investigated. Using a combination of absorption, fluorescence, circular dichroism (CD) spectra, thermal DNA denaturation as well as viscosity measurements, their binding modes and intrinsic binding constants (K(b)) to calf DNA (CT DNA) were comparatively studied and also compared with those of 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin (TMPyP). The results suggest that the K(b) values of these porphyrins are greatly influenced by the number of positive charges and steric hindrance. Theoretical calculations applying the density functional theory (DFT) have been carried out and explain their DNA-binding properties reasonably. The efficiency of DNA photocleavage by these porphyrins shows high dependence on the values of K(b).

Experimental and DFT studies on DNA binding and photocleavage of two cationic porphyrins. Effects of the introduction of a carboxyphenyl into pyridinium porphyrin.

The DNA-binding affinities and DNA photocleavage abilities of cationic porphyrin, 5-(4-carboxyphenyl)-10,15,20-tris(4-methylpyridiniumyl)porphyrin (CTMPyP), and its reference compound meso-tetrakis(N-methyl-4-pyridiniumyl)porphyrin (H2TMPyP) have been investigated. The DNA-binding behaviors of the two compounds in NaH2PO4 buffer were compared systematically by using absorption, fluorescence and circular dichroism (CD) spectra, thermal denaturation as well as viscosity measurements. The experimental results show that CTMPyP binds to DNA in an outside binding mode, while H2TMPyP in an intercalative mode. Photocleavage experiments reveal that both two compounds employ 1O2-mediated mechanism in cleaving DNA and H2TMPyP can cleave DNA more efficiently than CTMPyP. Theoretical calculations were carried out with the density functional theory (DFT), and the calculated results indicate that the character and energies of some frontier orbitals of CTMPyP are quite different from those of H2TMPyP. These theoretical results can be used to explain their different DNA-binding modes and affinities to a certain extent.