Satellite or ground-based measurements for air pollutants (PM2.5, PM10, SO2, NO2, O3) data and their health hazards: which is most accurate and why?

Air pollution is growing at alarming rates on regional and global levels, with significant consequences for human health, ecosystems, and change in climatic conditions. The present 12 weeks (4 October 2021, to 26 December 2021) study revealed the different ambient air quality parameters, i.e., PM2.5, PM10, SO2, NO2, and O3 over four different sampling stations of Delhi-NCR region (Dwarka, Knowledge park III, Sector 125, and Vivek Vihar), India, by using satellite remote sensing data (MERRA-2, OMI, and Aura Satellite) and different ground-based instruments. The ground-based observation revealed the mean concentration of PM2.5 in Dwarka, Knowledge park III, Sector 125, and Vivek Vihar as 279 µg m-3, 274 µg m-3, 294 µg m-3, and 365 µg m-3, respectively. The ground-based instrumental concentration of PM2.5 was greater than that of satellite observations, while as for SO2 and NO2, the mean concentration of satellite-based monitoring was higher as compared to other contaminants. Negative and positive correlations were observed among particulate matter, trace gases, and various meteorological parameters. The wind direction proved to be one of the prominent parameter to alter the variation of these pollutants. The current study provides a perception into an observable behavior of particulate matter, trace gases, their variation with meteorological parameters, their health hazards, and the gap between the measurements of satellite remote sensing and ground-based measurements.

Inulin coated Mn3O4 nanocuboids coupled with RNA interference reverse intestinal tumorigenesis in Apc knockout murine colon cancer models.

This study reports the development and pre-clinical evaluation of biodrug using RNA interference and nanotechnology. The major challenges in achieving targeted gene silencing in vivo include the stability of RNA molecules, accumulation into pharmacological levels, and site-specific targeting of the tumor. We report the use of Inulin for coating the arginine stabilized manganese oxide nanocuboids (MNCs) for oral delivery of shRNA to the gut. Furthermore, bio-distribution analysis exhibited site-specific targeting in the intestines, improved pharmacokinetic properties, and faster elimination from the system without cytotoxicity. To evaluate the therapeutic possibility and effectiveness of this multimodal bio-drug, it was orally delivered to Apc knockout colon cancer mice models. Persistent and efficient delivery of bio-drug was demonstrated by the knockdown of target genes and increased median survival in the treated cohorts. This promising utility of RNAi-Nanotechnology approach advocates the use of bio-drug in an effort to replace chemo-drugs as the future of cancer therapeutics.

Matrix metalloproteinase enzyme responsive delivery of 5-Fluorouracil using Collagen-I peptide functionalized Dendrimer-Gold nanocarrier.

OBJECTIVE: The aim was to develop matrix metalloproteinase 1 (MMP1) responsive nanoparticle system for the delivery of 5-fluorouracil (5Fu) anticancer drug. SIGNIFICANCE: The MMP1 in the cancer microenvironment-induced drug release have the advantage of targeted drug release and reduce the distribution of drug to the healthy tissues. METHOD: G5 poly(amidoamine) (PAMAM) dendrimer (G5)-coated gold nanoparticles (G5AuNP) were synthesized and loaded with 5Fu. The drug-loaded nanoparticles were further coated with collagen I (Col-I) peptide, which is a substrate for MMP1 enzyme (Col-I 5Fu@G5AuNP). RESULT: The nanoparticles were highly monodispersed with a particle size of 30 nm and showed high drug encapsulation efficiency. The release of drug from the nanoparticles in HEPES buffer pH 7.4 was faster, higher and better controlled when incubated with MMP1 enzyme. The half-maximum inhibitory concentration for Col-I 5Fu@G5AuNP was eight times lower than the 5Fu against MCF-7, suggesting the improved delivery and anticancer activity of 5Fu after encapsulation in the developed enzyme-responsive nanocarrier system. The computed tomography (CT) X-ray attenuation of Col-I@G5AuNP showed a good contrasting property. CONCLUSION: The formulation Col-I 5Fu@G5AuNP has improved anticancer activity than free drug and the CT imaging results are promising for its theranostic applications for breast cancer treatment.

Amorphous nano morin outperforms native molecule in anticancer activity and oral bioavailability.

In the past decade, naturally occurring phytoconstituents have emerged as potential therapeutic agents and alternative to synthetic drugs. However, efficient delivery of hydrophobic phytoconstituents into the body with desired therapeutic efficacy is a key challenge for the pharmaceutical industries due to their insolubility in water and low oral bioavailability. Nanosuspension formulations have shown promises to improve the delivery of the hydrophobic molecules with simultaneously avoiding the drawbacks like carrier toxicity and scale-up issues of other nanotechnology-based drug delivery systems. In this study, we have used morin hydrate (MH), a flavonol, and developed MH nanosuspension formulation (MHNS) to improve its poor physiochemical properties and low oral bioavailability. Different stabilizers with varying concentrations were investigated for preparing nanosuspension. MHNS was characterized by DLS, TEM, FTIR, DSC, powder XRD and was evaluated for its solubility, dissolution, partition coefficient, in-vitro anticancer activity and pharmacokinetics in rats. The optimized nanosuspension formulation, with a size of <100 nm, is capable of increasing aqueous solubility, dissolution rate, and oral bioavailability of MH. Moreover, the therapeutic efficacy, in terms of cytotoxicity to human lung cancer cells, of MH was also increased after formulating into nanosuspension form.

Which is a stronger indicator of dental caries: oral hygiene, food, or beverage? A clinical study.

Dental caries is a multifactorial disease with various risk factors. Oral hygiene and dietary factors--specifically, the consumption of snacks and beverages with added sugars--have been shown to be risk indicators for this disease. It is critical for dental professionals to understand the relative roles of each of these food categories in the dental caries process. This article presents a cross-sectional study of 76 people living in a Southern Illinois fluoridated community. The amount of sugar-sweetened beverages, snack food consumption, plaque index, and age showed statistically significant relationships with the outcome variable--dental caries (P < 0.05). The results indicated that dietary factors and oral hygiene both contribute equally to dental caries in young adults living in a fluoridated community. Sugar-sweetened beverage consumption was a much stronger indicator of dental caries than snack food consumption in our study population.

Design of manganese-based nanomaterials for pharmaceutical and biomedical applications.

In the past few years, manganese-based nanostructures have been extensively investigated in the biomedical field particularly to design highly biocompatible theranostics, which can not only act as efficient diagnostic imaging contrast agents but also deliver the drugs to the target sites. The nanoscale size, large surface area-to-volume ratio, availability of cheap precursors, flexibility to synthesize nanostructures with reproducible properties and high yield, and easy scale up are the major reasons for the attraction towards manganese nanostructures. Along with these properties, the nontoxic nature, pH-sensitive degradation, and easy surface functionalization are additional benefits for the use of manganese nanostructures in biomedical and pharmaceutical sciences. Therefore, in this review, we discuss the recent progress made in the synthesis of manganese nanostructures, describe the attempts made to modify their surfaces to impart biocompatibility and stability in biological fluids, and critically discuss their use in magnetic resonance imaging, drug and gene delivery, hyperthermia, photothermal/photodynamic, immunotherapy, biosensing and tumor diagnosis.

Primary renal leukaemia in a young adult male as an extramedullary presentation of T cell acute lymphoblastic leukaemia.

Primary renal involvement by T lymphoblasts is rare among adults with T acute lymphoblastic leukaemia. We report a 28-year-old man presenting with acute renal failure due to infiltration by T lymphoblasts and his response to paediatric-inspired modified BFM-90 protocol. The patient achieved an initial complete remission (CR) but developed central nervous system relapse. He achieved CR2 with cranial irradiation and intrathecal chemotherapy. He underwent a haploidentical transplant in CR2 and remains in remission post-transplant day 330. An early kidney biopsy helped confirm the diagnosis. Such presentations remain responsive to modified BFM-90. An early allotransplant in CR2 remains the standard of care.

Microencapsulated Saccharomyces cerevisiae column bioreactor for potential use in renal failure uremia.

A novel bioreactor containing viable APA microencapsulated yeast cells was designed. Rat plasma was used for perfusion. Yeast cell loading and perfusion flow rate were studied to maximize urea removal. An increase in column loading from 25% to 100%, increased urea removal from 5.67 ± 1.34% to 30.45 ± 0.48%. An increase in flow rate from low to high, increased urea removal from 30.46% to 40.4%. At 100% column loading and high flow rate, the creatinine and phosphate concentrations decreased by 22% and 10%, respectively, while ammonia concentrations increased by 58.9% (p < 0.05). Our in-vitro perfusion study demonstrates that microencapsulated yeast cells can remove urea efficiently.

A comparison of sports and energy drinks--Physiochemical properties and enamel dissolution.

The consumption of sports and energy drinks by children and adolescents has increased at an alarming rate in recent years. It is essential for dental professionals to be informed about the physiochemical properties of these drinks and their effects on enamel. The present study measured the fluoride levels, pH, and titratable acidity of multiple popular, commercially available brands of sports and energy drinks. Enamel dissolution was measured as weight loss using an in vitro multiple exposure model consisting of repeated short exposures to these drinks, alternating with exposure to artificial saliva. The relationship between enamel dissolution and fluoride levels, pH, and titratable acidity was also examined. There was a statistically significant difference between the fluoride levels (p = 0.034) and pH (p = 0.04) of the sports and energy drinks studied. The titratable acidity of energy drinks (11.78) was found to be significantly higher than that of sports drinks (3.58) (p < 0.001). Five of the energy drinks (Red Bull Sugar Free, Monster Assault, Von Dutch, Rockstar, and 5-Hour Energy) were found to have the highest titratable acidity values among the brands studied. Enamel weight loss after exposure to energy drinks was significantly higher than it was after exposure to sports drinks. The effect of titratable acidity on enamel weight loss was found to vary inversely with the pH of the drinks. The findings indicated that energy drinks have significantly higher titratable acidity and enamel dissolution associated with them than sports drinks. Enamel weight loss after exposure to energy drinks was more than two times higher than it was after exposure to sports drinks. Titratable acidity is a significant predictor of enamel dissolution, and its effect on enamel weight loss varies inversely with the pH of the drink. The data from the current study can be used to educate patients about the differences between sports and energy drinks and the effects of these drinks on tooth enamel.

Biotinylated Mn3O4 nanocuboids for targeted delivery of gemcitabine hydrochloride to breast cancer and MRI applications.

Multifunctional nanocarriers have been found as potential candidate for the targeted drug delivery and imaging applications. Herein, we have developed a biocompatible and pH-responsive manganese oxide nanocuboid system, surface modified with poly (ethylene glycol) bis(amine) and functionalized with biotin (Biotin-PEG-MNCs), for an efficient and targeted delivery of an anticancer drug (gemcitabine, GEM) to the human breast cancer cells. GEM-loaded Biotin-PEG@MNCs showed high drug loading efficiency, controlled release of GEM and excellent storage stability in the physiological buffers and different temperature conditions. GEM-loaded Biotin-PEG@MNCs showed dose- and time-dependent decrease in the viability of human breast cancer cells. Further, it exhibited significantly higher cell growth inhibition than pure GEM which suggested that Biotin-PEG@MNCs has efficiently delivered the GEM into cancerous cells. The role of biotin in the uptake was proved by the competitive binding-based cellular uptake study. A significant decrease in the amount of manganese was observed in biotin pre-treated cancer cells as compared to biotin untreated cancer cells. In MRI studies, Biotin-PEG-MNCs showed both longitudinal and transverse relaxivity about 0.091 and 7.66 mM-1 s-1 at 3.0 T MRI scanner, respectively. Overall, the developed Biotin-PEG-MNCs presents a significant potential in formulation development for cancer treatment via targeted drug delivery and enhanced MRI contrast imaging properties.

Self-assembled and pH-responsive polymeric nanomicelles impart effective delivery of paclitaxel to cancer cells.

Chemotherapy is an essential component of breast cancer therapy, but it is associated with serious side effects. Herein, a pluronic F68-based pH-responsive, and self-assembled nanomicelle system was designed to improve the delivery of paclitaxel (PTX) to breast cancer cells. Two pH-responsive pluronic F68-PTX conjugates i.e. succinoyl-linked conjugate (F68-SA-PTX) and cis-aconityl-linked conjugate (F68-CAA-PTX) were designed to respond the varying pH-environment in tumour tissue. Although both the linkers showed pH-sensitivity, the F68-CAA-PTX exhibited superior pH-sensitivity over the F68-SA-PTX and achieved a more selective release of PTX from the self-assembled nanomicelles. The prepared nanomicelles were characterized by dynamic light scattering, transmittance electron microscopy, differential scanning calorimetry and powder X-ray diffraction techniques. The anticancer activity of prepared nanomicelles and pure PTX were evaluated by 2D cytotoxicity assay against breast cancer cell line MDA-MB-231 and in the real tumour environments i.e. 3D tumor spheroids of MDA-MB-231 cells. The highest cytotoxicity effect of PTX was observed with F68-CAA-PTX nanomicelles followed by F68-SA-PTX and free PTX. Further, the F68-CAA-PTX nanomicelles also induced significant apoptosis with a combination of increase in ROS generation, decrease in the depolarisation of MMP and G2/M cell cycle arrest. These observed results provide a new insight for breast cancer treatment using pluronic nanomicelles.

Inulin-pluronic-stearic acid based double folded nanomicelles for pH-responsive delivery of resveratrol.

Herein, we introduce a novel amphiphilic bioconjugate (INU-F68-SA), synthesized by functionalization of pluronic F68 with a polysaccharide inulin (INU) and a lipid stearic acid (SA). The synthesis of INU-F68-SA was confirmed by FTIR and 1H-NMR analysis. INU-F68-SA can self-assemble into nanomicelles and therefore, its application in delivering of hydrophobic resveratrol (RSV) was investigated. The RSV-loaded INU-F68-SA nanomicelles (RSNM) had about 172 nm size, spherical shape, 0.237 polydispersity index, and -18 mV zeta potential. More importantly, the RSNM showed high drug entrapment efficiency, controlled drug release and protection of drug during storage. The RSNM significantly enhanced the cytotoxicity of RSV against colorectal cancer cells by inducing apoptosis and changing mitochondrial membrane potential. Further, in-vivo pharmacokinetic experiment indicated an improvement in pharmacokinetics of RSV after administering as RSNM. Thus, the use of self-assembled nanomicelles of amphiphilic INU-F68-SA bioconjugate could be a better alternative to overcome the poor in-vitro and in-vivo performance of RSV.

Baicalin encapsulating lipid-surfactant conjugate based nanomicelles: Preparation, characterization and anticancer activity.

Lung cancer is one of the most common malignant tumors and emerged as one of the leading causes of cancer-related death worldwide. Surgical resection can be a curative treatment for early stage but the most of lung cancer patients are diagnosed at an advanced stage when the pulmonary tumor has been invaded beyond the respiratory system. Therefore, chemotherapy is suitable for curing metastasized tumor. Baicalin (BL) is a flavonoid which has been studied in the treatment of several types of cancer including lung cancer. However, its low solubility in water and non-specificity impede its practical utilization. Hence, we have reported a stearic acid and pluronic F68 conjugated nanomicelles (PF68-SA) system to improve therapeutic efficacy of BL. Solvent evaporation method was used to prepare the BL-loaded PF68-SA nanomicelles (BLNM). The designed BLNM were characterized for the particle size, surface charge, critical micelle concentration, colloidal stability, morphology, and total drug content. BLNM formulation showed improved toxicity of BL against A549 human lung cancer cells in cytotoxicity assay. Further, apoptosis study also depicted BLNM-induced cell death in A549 cells. Therefore, the synthesized fatty acid-modified polymeric nanomicellar system could be useful in overcoming the stability and low therapeutic efficacy issues of hydrophobic anticancer drugs like BL and delivering them to the cancer cells.

Modulating the Delivery of 5-Fluorouracil to Human Colon Cancer Cells Using Multifunctional Arginine-Coated Manganese Oxide Nanocuboids with MRI Properties.

5-Fluorouracil (5-FU) is one of the most prescribed drugs and the major component of chemotherapy for the treatment of colorectal cancer. In this study, we have designed arginine-functionalized manganese oxide nanocuboids (Arg@MNCs) for the effective delivery of 5-FU to colon cancer cells. Arginine was used as multifunctional agent to provide stability to MNCs, achieve high drug loading, control the release of loaded drug, and improve delivery to cancer cells. The synthesized Arg@MNCs were characterized by DLS, TEM, XRD, FTIR, XPS, TGA, and VSM analysis. The structural and morphological analysis by TEM showed cuboid-shaped MNCs with average particle size ∼15 nm. Biodegradation studies indicated that the Arg@MNCs were degraded at endolyosomal pH in 24 h while remaining stable at physiological pH. Hemolytic toxicity studies revealed the safety and nontoxic nature of the prepared MNCs. 5-FU-loaded Arg@MNCs showed significant control over the release of 5-FU, decrease in the hemolytic toxicity of loaded 5-FU but higher in vitro anticancer activity against HCT 116 and SW480 human colon cancer cells. Importantly, both the bare MNCs and Arg@MNCs showed excellent T1 and T2MR relaxivity under 3.0 T MRI scanner. Thus, the nanostructures developed in this study, i.e., 5-FU-Arg@MNCs could overcome the issues of both MNCs (stability) and 5-FU (low drug loading and nonspecificity) and may be used as a multifunctional theranostic nanocarrier for colon cancer treatment.

Serotonin-Stearic Acid Bioconjugate-Coated Completely Biodegradable Mn3O4 Nanocuboids for Hepatocellular Carcinoma Targeting.

In this study, a serotonin-stearic acid (ST-SA)-based bioconjugate was synthesized for the surface modification of manganese oxide-based nanocuboids (MNCs) for delivering of anticancer drug (i.e., doxorubicin hydrochloride (DOX)) to human liver cancer cells. MNCs were synthesized by chemical precipitation method, and their surface was modified with ST-SA bioconjugate for targeting of MNCs to cancer cells. The ST-SA@MNCs along with DOX showed good colloidal stability, high drug encapsulation (98.3%), and drug loading efficiencies (22.9%) as well as pH-responsive biodegradation. Coating with ST-SA conjugate provided a shield to MNCs which sustained their degradation in an acidic environment. The release of DOX was higher (81.4%) in acidic media than under the physiological conditions (20.5%) up to 192 h. The in vitro anti-proliferation assay showed that ST-SA@MNCs exhibit higher cell growth inhibition compared to that of pure DOX after 48 h of treatment. The cellular uptake and apoptosis studies revealed the enhanced uptake of ST-SA@MNCs in contrast to the MNCs due to overexpressed ST receptor on hepatocellular carcinoma cells and triggered the generation of reactive oxygen species in the cells. Therefore, these results indicated that the DOX-loaded, ST-SA stabilized MNCs improved the therapeutic index of DOX and would be a promising therapeutic candidate for tumor therapy.

Clinical implications of cytogenetic heterogeneity in Philadelphia chromosome positive (Ph+) adult B cell acute lymphoblastic leukemia following tyrosine kinase inhibitors and chemotherapy regimens.

We retrospectively studied a cohort of 144 adults with Philadelphia chromosome/BCR-ABL1 positive B acute lymphoblastic leukemia (Ph + B-ALL) to assess the clinical implications of cytogenetic heterogeneity in this disease. The study group included 85 men and 59 women that were sorted into 6 subgroups based on karyotypic findings in the stemline as follows: 32 patients with t(9;22) as a sole aberration, 23 with t(9;22) plus 1 additional chromosomal abnormality (ACA), 26 with t(9;22) as part of a complex karyotype, 18 showing a variant-/complex- t(9;22), 30 with t(9;22) as the stemline with ACAs in the sideline(s), and 15 patients who had the t(9;22) and hyperdiploidy. In 89 patients 1 clone was identified; 41 had 2 clones and 14 had ≥ 3 clone(s). The median overall survival (OS) was 25.6 months and the median relapse-free survival (RFS) was 20.6 months. Patients with variant-/complex- t(9;22) had poorer OS and RFS when compared with all other subgroups combined (P = 0.0018 and P = 0.0049, respectively). In addition, patients with ≥ 2 clones had worse OS and RFS than patients with 1 clone (P = 0.0179 and P = 0.0429, respectively). Multivariate analysis confirmed that variant-/complex-t(9;22) and clone number are independent risk factors. We suggest that conventional chromosomal analysis is of clinical importance for risk stratification of B-ALL patients.

Realigning biomedical science instruction in predoctoral curricula: a proposal for change.

Currently in North America, there is an active dialogue going on about the state of predoctoral dental education and the need for curriculum change, innovation, and the adoption of contemporary, competency-based educational models. At the institutional level, curriculum committees struggle with requests from faculty to add new content to an overburdened didactic and clinic schedule. This article will describe potential solutions centering on the role and scope of the biomedical sciences in predoctoral dental education. The authors propose that dental educators and institutions reconsider the current admission prerequisites and curriculum content of the biomedical sciences in predoctoral programs. The proposed changes are intended to eliminate content redundancy between undergraduate and predoctoral dental education by integration of the biomedical sciences--in particular, biochemistry, microbiology, and physiology--into other clinically oriented coursework and learning experiences in the curriculum based on a pathophysiology model that fosters students' comprehension of the etiology of oral and systemic diseases encountered by the general dental practitioner. The authors explore how changes in the biomedical science prerequisites for dental school matriculation and associated modifications in curriculum focus and content would impact admissions testing, composition of national board exams, and strategies for teaching and learning within dental schools.

Spatial and temporal patterns of alkaloid variation in the poison frog Oophaga pumilio in Costa Rica and Panama over 30 years.

A total of 232 alkaloids, representing 21 structural classes were detected in skin extracts from the dendrobatid poison frog Oophaga pumilio, collected from 53 different populations from over 30 years of research. The highly toxic pumiliotoxins and allopumiliotoxins, along with 5,8-disubstitiuted and 5,6,8-trisubstituted indolizidines, all of which are proposed to be of dietary mite origin, were common constituents in most extracts. One decahydroquinoline (DHQ), previously shown be of ant origin, occurred in many extracts often as a major alkaloid, while other DHQs occurred rather infrequently. Histrionicotoxins, thought to be of ant origin, did not appear to possess a specific pattern of occurrence among the populations, but when present, were usually found as major components. Certain 3,5-disubstituted pyrrolizidines and indolizidines, known to be of ant origin, did occur in extracts, but infrequently. Alkaloid composition differed with regard to geographic location of frog populations, and for populations that were sampled two or more times during the 30-year period significant changes in alkaloid profiles sometimes occurred. The results of this study indicate that chemical defense in a dendrobatid poison frog is dependent on geographic location and habitat type, which presumably controls the abundance and nature of alkaloid-containing arthropods.

Commercial soft drinks: pH and in vitro dissolution of enamel.

Most soft drinks are acidic in nature and exposure to these drinks may result in enamel erosion. This study sought to measure the pH of 20 commercial brands of soft drinks, the dissolution of enamel resulting from immersion in these drinks, and the influence of pH on enamel loss. Comparison of the erosive potential of cola versus non-cola drinks as well as regular sugared and diet versions of the same brands was undertaken. The pH was measured immediately after opening the soft drink can. Enamel slices obtained from freshly extracted teeth were immersed in the soft drinks and weighed at baseline and after 6, 24, and 48 hours of immersion. Non-cola drinks had significantly higher pH values than cola drinks but showed higher mean percent weight loss. By contrast, sugared versions of the cola and non-cola drinks showed significantly lower pH values and higher mean percent weight loss than their diet counterparts. The pH value of the soft drink did not have a significant influence on the mean percent weight loss (r = -0.28). Prolonged exposure to soft drinks can lead to significant enamel loss. Non-cola drinks are more erosive than cola drinks. Sugared versions of cola and non-cola drinks proved to be more erosive than their diet counterparts. The erosive potential of the soft drinks was not related to their pH value.

Depth of cure and microleakage with high-intensity and ramped resin-based composite curing lights.

BACKGROUND: The authors conducted a study to determine whether high-intensity curing lights in high and ramped intensity modes affect microleakage of resin-based composite restorations and whether different types of resin-based composites meet American National Standards Institute/American Dental Association Specification no. 27 (1993): 7.7 for depth of cure when polymerized using these lights. METHODS: The authors compared five high-intensity lights, three plasma arc lights and two quartz-tungsten-halogen lights in their regular and ramped intensity modes with a quartz-tungsten-halogen 40-second light. The parameters tested were microleakage one month after bonding and curing depth for different resin-based composite types. The authors measured curing depth using a scratch test. RESULTS: Light curing with Optilux 501 (Kerr/Demetron, Orange, Calif.) for 10 seconds and ADT Power PAC (American Dental Technologies, Corpus Christi, Texas) for 10 seconds resulted in higher microleakage values than light curing with other lights (P < .05). The microhybrid resin-based composite was the only material that met the specification when light cured with all of the lights tested. The flowable resin-based composite did not meet the specification when light cured with all lights tested. Microhybrid resin-based composite had the greatest depth of cure, and flowable resin-based composite had the least depth of cure. CONCLUSIONS: Microhybrid resin-based composite microleakage is affected by some light-curing modes. Different categories of resin-based composites are cured to different depths using high-intensity lights. CLINICAL IMPLICATIONS: Light curing with some high-intensity lights compared with halogen lights may result in higher microleakage values. Use caution when light curing flowable resin-based composite with the high-intensity lights. Place increments less than 2 millimeters in depth when using this material.