Diffusion of peroxides through dentine in vitro with and without prior use of a desensitizing varnish

Different bleaching regimens are used in dentistry possibly penetrating the dentine and affecting the pulp. The aim of the present study was to investigate peroxide diffusion through dentine pre-treated with a desensitizing varnish (Vivasens®) in a standardized in vitro setup during application of different bleaching materials. The penetration was tested using 1.3-mm-thick bovine dentine slabs. The following bleaching materials were tested with and without prior application of the desensitizing varnish on the external side of the dentine slabs: Vivastyle, Whitestrips, Simply White, Opalescence (external bleaching), and sodium perborate (internal bleaching, only tested without varnish; n = 8 samples per subgroup). The penetration of peroxides was measured photometrically using 4-aminoantipyrin as a substrate, the penetration of peroxides was monitored over 240 min. All bleaching agents yielded a diffusion of peroxides through the dentine, the kinetics of penetration were approximately linear for all materials tested. The significantly highest diffusion of peroxides was observed with Opalescence, the lowest with sodium perborate. The adoption of the desensitizing varnish reduced the diffusion of peroxides significantly for all external bleaching materials. Peroxides penetrated the dentine during application of bleaching materials; the penetration of peroxides can be reduced by application of a desensitizing agent

Characterization of Developmental Pathway of Natural Killer Cells from Embryonic Stem Cells In Vitro

In vitro differentiation of embryonic stem (ES) cells is often used to study hematopoiesis. However, the differentiation pathway of lymphocytes, in particular natural killer (NK) cells, from ES cells is still unclear. Here, we used a multi-step in vitro ES cell differentiation system to study lymphocyte development from ES cells, and to characterize NK developmental intermediates. We generated embryoid bodies (EBs) from ES cells, isolated CD34(+) EB cells and cultured them on OP9 stroma with a cocktail of cytokines to generate cells we termed ES-derived hematopoietic progenitors (ES-HPs). EB cell subsets, as well as ES-HPs derived from EBs, were tested for NK, T, B and myeloid lineage potentials using lineage specific cultures. ES-HPs derived from CD34(+) EBs differentiated into NK cells when cultured on OP9 stroma with IL-2 and IL-15, and into T cells on Delta-like 1-transduced OP9 (OP9-DL1) with IL-7 and Flt3-L. Among CD34(+) EB cells, NK and T cell potentials were detected in a CD45(−) subset, whereas CD45(+) EB cells had myeloid but not lymphoid potentials. Limiting dilution analysis of ES-HPs generated from CD34(+)CD45(−) EB cells showed that CD45(+)Mac-1(−)Ter119(−) ES-HPs are highly enriched for NK progenitors, but they also have T, B and myeloid potentials. We concluded that CD45(−)CD34(+) EB cells have lymphoid potential, and they differentiate into more mature CD45(+)Lin(−) hematopoietic progenitors that have lymphoid and myeloid potential. NK progenitors among ES-HPs are CD122(−) and they rapidly acquire CD122 as they differentiate along the NK lineage

β1 Integrin-Mediated Adhesion Signalling Is Essential for Epidermal Progenitor Cell Expansion

Background: There is a major discrepancy between the in vitro and in vivo results regarding the role of b1 integrins in the maintenance of epidermal stem/progenitor cells. Studies of mice with skin-specific ablation of b1 integrins suggested that epidermis can form and be maintained in their absence, while in vitro data have shown a fundamental role for these adhesion receptors in stem/progenitor cell expansion and differentiation. Methodology/Principal Findings: To elucidate this discrepancy we generated hypomorphic mice expressing reduced b1 integrin levels on keratinocytes that developed similar, but less severe defects than mice with b1-deficient keratinocytes. Surprisingly we found that upon aging these abnormalities attenuated due to a rapid expansion of cells, which escaped or compensated for the down-regulation of b1 integrin expression. A similar phenomenon was observed in aged mice with a complete, skin-specific ablation of the b1 integrin gene, where cells that escaped Cre-mediated recombination repopulated the mutant skin in a very short time period. The expansion of b1 integrin expressing keratinocytes was even further accelerated in situations of increased keratinocyte proliferation such as wound healing. Conclusions/Significance: These data demonstrate that expression of b1 integrins is critically important for the expansion of epidermal progenitor cells to maintain epidermal homeostasis

The 2022 symposium on dementia and brain aging in low- and middle-income countries: Highlights on research, diagnosis, care, and impact

\ua9 2024 The Authors. Alzheimer\u27s & Dementia published by Wiley Periodicals LLC on behalf of Alzheimer\u27s Association.Two of every three persons living with dementia reside in low- and middle-income countries (LMICs). The projected increase in global dementia rates is expected to affect LMICs disproportionately. However, the majority of global dementia care costs occur in high-income countries (HICs), with dementia research predominantly focusing on HICs. This imbalance necessitates LMIC-focused research to ensure that characterization of dementia accurately reflects the involvement and specificities of diverse populations. Development of effective preventive, diagnostic, and therapeutic approaches for dementia in LMICs requires targeted, personalized, and harmonized efforts. Our article represents timely discussions at the 2022 Symposium on Dementia and Brain Aging in LMICs that identified the foremost opportunities to advance dementia research, differential diagnosis, use of neuropsychometric tools, awareness, and treatment options. We highlight key topics discussed at the meeting and provide future recommendations to foster a more equitable landscape for dementia prevention, diagnosis, care, policy, and management in LMICs. Highlights: Two-thirds of persons with dementia live in LMICs, yet research and costs are skewed toward HICs. LMICs expect dementia prevalence to more than double, accompanied by socioeconomic disparities. The 2022 Symposium on Dementia in LMICs addressed advances in research, diagnosis, prevention, and policy. The Nairobi Declaration urges global action to enhance dementia outcomes in LMICs

Partial loss of heterozygosity events at the mutated gene in tumors from MLH1/MSH2 large genomic rearrangement carriers

<p>Abstract</p> <p>Background</p> <p>Depending on the population studied, large genomic rearrangements (LGRs) of the mismatch repair (<it>MMR</it>) genes constitute various proportions of the germline mutations that predispose to hereditary non-polyposis colorectal cancer (HNPCC). It has been reported that loss of heterozygosity (LOH) at the LGR region occurs through a gene conversion mechanism in tumors from <it>MLH1</it>/<it>MSH2 </it>deletion carriers; however, the converted tracts were delineated only by extragenic microsatellite markers. We sought to determine the frequency of LGRs in Slovak HNPCC patients and to study LOH in tumors from LGR carriers at the LGR region, as well as at other heterozygous markers within the gene to more precisely define conversion tracts.</p> <p>Methods</p> <p>The main <it>MMR </it>genes responsible for HNPCC, <it>MLH1</it>, <it>MSH2</it>, <it>MSH6</it>, and <it>PMS2</it>, were analyzed by MLPA (multiplex ligation-dependent probe amplification) in a total of 37 unrelated HNPCC-suspected patients whose <it>MLH1/MSH2 </it>genes gave negative results in previous sequencing experiments. An LOH study was performed on six tumors from LGR carriers by combining MLPA to assess LOH at LGR regions and sequencing to examine LOH at 28 SNP markers from the <it>MLH1 </it>and <it>MSH2 </it>genes.</p> <p>Results</p> <p>We found six rearrangements in the <it>MSH2 </it>gene (five deletions and dup5-6), and one aberration in the <it>MLH1 </it>gene (del5-6). The <it>MSH2 </it>deletions were of three types (del1, del1-3, del1-7). We detected LOH at the LGR region in the single <it>MLH1 </it>case, which was determined in a previous study to be LOH-negative in the intragenic D3S1611 marker. Three tumors displayed LOH of at least one SNP marker, including two cases that were LOH-negative at the LGR region.</p> <p>Conclusion</p> <p>LGRs accounted for 25% of germline <it>MMR </it>mutations identified in 28 Slovakian HNPCC families. A high frequency of LGRs among the <it>MSH2 </it>mutations provides a rationale for a MLPA screening of the Slovakian HNPCC families prior scanning by DNA sequencing. LOH at part of the informative loci confined to the <it>MLH1 </it>or <it>MSH2 </it>gene (heterozygous LGR region, SNP, or microsatellite) is a novel finding and can be regarded as a partial LOH. The conversion begins within the gene, and the details of conversion tracts are discussed for each case.</p

Carbamide peroxide gel stability under different temperature conditions: is manipulated formulation an option?

Nowadays the use of gel containing carbamide peroxide (CP) prepared in Pharmacy is a normal practice in the population. However, the quality of this product is questionable concerning its stability. The aim of this study is was to synthesize and to analyze this drug alone or associated to Carbopol gel through analytical methodology compatible with the routine of the Pharmacies. The reaction between urea and hydrogen peroxide was carried out at different resting times: 24 hours (CP 24 powder) and 48 hours (CP48 powder) after the mixture. Both products were associated with Carbopol 940® gel 1.5% (G) generating G24 and G48 samples. The stability of powders (CP24 e CP48) and the formulations (G24 and G48) were evaluated as a function of time (15, 40 and 45 days) and thermal variation (refrigeration: 8 °C±1; thermal shock 32 °C±1 /8 °C±1; stove: 32 °C±1), using a standard titration method. As a result, only under refrigeration the CP24 and CP48 contents remained stable during the period of 45 days. An interesting finding was that G24 and G48 presented greater stability for at least 45-days under refrigeration and thermal shock conditions, and up to 30 days under stove conditions. The results for the G24 and G48 were slightly higher than those obtained for the control. Therefore, we were able to conclude that association with Carbopol 940® Gel 1.5 % provided greater CP stability and that manipulated formulations containing CP may be viable for use in a period of 45 days under refrigeration conditions. The titration proved to be an effective technique for the analysis of CP with or without Carbopol 940® gel 1.5%.Atualmente, a utilização de gel contendo peróxido de carbamida manipulado em Farmácia é uma prática comum na população. No entanto, a qualidade deste produto é questionada, sobretudo no que se refere à estabilidade deste fármaco. O objetivo deste trabalho consiste na avaliação da viabilidade de sintetizar e analisar quantitativamente este fármaco associado ou não a um gel de Carbopol através de metodologia analítica compatível com a rotina das Farmácias. A reação entre a uréia e o peróxido de hidrogênio foi realizada em tempos diferentes de repouso após a mistura, 24 h para sintetizar o pó PC 24 e 48 h para o pó CP 48. Estes pós foram associados a um gel (G) de Carbopol 940® 1,5 %, originando as amostras G24 e G48. A estabilidade dos pós (PC 24 e PC 48) e das formulações (G 24 e G 48) foi avaliada em função do tempo (15, 40 e 45 dias) e da variação térmica (refrigeração: 8 °C±1; choque térmico: 32 °C±1/8 °C±1 e estufa: 32 °C±1), através da técnica de titulometria. Os resultados indicam que unicamente sob refrigeração o CP24 e o CP 48 mantiveram-se estáveis no período de 45 dias. O G24 e o G48 apresentaram estáveis por pelo menos 45 dias nas condições de refrigeração e choque térmico e por 30 dias na condição estufa. Os resultados obtidos para o G24 e G48 foram ligeiramente superiores aos obtidos para o controle. Além disso, é possível concluir que a associação do PC com o gel de Carbopol 940® 1,5 % promoveu um aumento na estabilidade do PC e que as preparações manipuladas contendo PC são viáveis para uso durante um período de 45 sob refrigeração. A titulometria mostrou-se uma técnica eficaz para a análise do PC associado ou não ao gel de Carbopol 940® 1,5%