Therapeutic Potential of Hydrogen Sulfide in Reproductive System Disorders.

Hydrogen sulfide (H2S), previously regarded as a toxic exhaust and atmospheric pollutant, has emerged as the third gaseous signaling molecule following nitric oxide (NO) and carbon monoxide (CO). Recent research has revealed significant biological effects of H2S in a variety of systems, such as the nervous, cardiovascular, and digestive systems. Additionally, H2S has been found to impact reproductive system function and may have therapeutic implications for reproductive disorders. This paper explores the relationship between H2S and male reproductive disorders, specifically erectile dysfunction, prostate cancer, male infertility, and testicular damage. Additionally, it examines the impact of H2S regulation on the pathophysiology of the female reproductive system, including improvements in preterm birth, endometriosis, pre-eclampsia, fetal growth restriction, unexplained recurrent spontaneous abortion, placental oxidative damage, embryo implantation, recovery of myometrium post-delivery, and ovulation. The study delves into the regulatory functions of H2S within the reproductive systems of both genders, including its impact on the NO/cGMP pathway, the activation of K+ channels, and the relaxation mechanism of the spongy smooth muscle through the ROCK pathway, aiming to broaden the scope of potential therapeutic strategies for treating reproductive system disorders in clinical settings.

Synergistic effect of collagen cross-linking and remineralization for improving resin-dentin bond durability.

In this study, the synergistic effect of glutaraldehyde-cross-linking and remineralization on the strength and durability of resin-dentin bonds was investigated. Dentin surfaces were etched with 35% phosphoric acid. The control specimens were bonded with Adper Single Bond 2 using wet bonding without pretreatment. The experimental specimens were pretreated with 5% (v/v) glutaraldehyde solution for 3 min and placed in a remineralizing solution for 0, 12, and 24 h, followed by dry bonding. After performing composite build-ups on the specimens, they were longitudinally sectioned, immediately, and after aging for 3 h with sodium hypochlorite (NaOCl), to evaluate microtensile bond strength (µTBS). The cross-linked specimens exhibited µTBS values comparable with those of the control group, but the µTBS decreased significantly after NaOCl aging. The cross-linked dentin remineralized for 24 h exhibited an increase in µTBS. After aging in NaOCl, the µTBS of the specimens remineralized for 24 h did not decrease and was significantly higher than for the other experimental groups. Cross-linking with dry bonding maintained µTBS in specimens before aging in NaOCl, but the bonding durability was compromised. Remineralization of cross-linked dentin for 24 h followed by dry bonding increased the immediate µTBS and improved bond durability. Therefore, combining cross-linking with remineralization of collagen fibrils progressively increased resistance to degradation, improving bond durability.

Post-translational modifications of Keap1: the state of the art.

The Keap1-Nrf2 signaling pathway plays a crucial role in cellular defense against oxidative stress-induced damage. Its activation entails the expression and transcriptional regulation of several proteins involved in detoxification and antioxidation processes within the organism. Keap1, serving as a pivotal transcriptional regulator within this pathway, exerts control over the activity of Nrf2. Various post-translational modifications (PTMs) of Keap1, such as alkylation, glycosylation, glutathiylation, S-sulfhydration, and other modifications, impact the binding affinity between Keap1 and Nrf2. Consequently, this leads to the accumulation of Nrf2 and its translocation to the nucleus, and subsequent activation of downstream antioxidant genes. Given the association between the Keap1-Nrf2 signaling pathway and various diseases such as cancer, neurodegenerative disorders, and diabetes, comprehending the post-translational modification of Keap1 not only deepens our understanding of Nrf2 signaling regulation but also contributes to the identification of novel drug targets and biomarkers. Consequently, this knowledge holds immense importance in the prevention and treatment of diseases induced by oxidative stress.

Tannic acid induces dentin biomineralization by crosslinking and surface modification.

It is currently known that crosslinking agents can effectively improve the mechanical properties of dentin by crosslinking type I collagen. However, few scholars have focused on the influence of crosslinking agents on the collagen-mineral interface after crosslinking. Analysis of the Fourier transform infrared spectroscopy (FTIR) results showed that hydrogen bonding occurs between the tannic acid (TA) molecule and the collagen. The crosslinking degree of TA to collagen reached a maximum 41.28 ± 1.52. This study used TA crosslinked collagen fibers to successfully induce dentin biomineralization, and the complete remineralization was achieved within 4 days. The crosslinking effect of TA can improve the mechanical properties and anti-enzyme properties of dentin. The elastic modulus (mean and standard deviation) and hardness values of the remineralized dentin pretreated with TA reached 19.1 ± 1.12 GPa and 0.68 ± 0.06 GPa, respectively, which were close to those of healthy dentin measurements, but significantly higher than those of dentin without crosslinking (8.91 ± 1.82 GPa and 0.16 ± 0.01 GPa). The interface energy between the surface of collagen fibers and minerals decreased from 10.59 mJ m-2 to 4.19 mJ m-2 with the influence of TA. The current work reveals the importance of tannic acid crosslinking for dentin remineralization while providing profound insights into the interfacial control of biomolecules in collagen mineralization.

Promotion effect of immobilized chondroitin sulfate on intrafibrillar mineralization of collagen.

Chondroitin sulfate (CS) is widespread in mineralized tissues and is considered to play crucial roles during the mineralization process. However, its role in biomineralization remains controversial. In the present study, CS is immobilized to collagen fibrils to mimic its state in biomineralization. The results demonstrate that immobilized CS on collagen fibrils accelerates calcium phosphate nucleation and significantly promotes collagen mineralization by accumulating calcium ions in collagen fibrils. The stochastic optical reconstruction microscopy results confirm that CS gives the specific nucleation sites for calcium phosphate to preferentially form, the improved intrafibrillar heterogeneous nucleation of calcium phosphate facilitates intrafibrillar mineralization. It is found remarkably accelerated remineralization of CS immobilized demineralized dentin is achieved. This study offers insight on the understanding of the function of the biomacromolecule CS on the biomineralization front. In addition, CS effectively promotes intrafibrillar mineralization, which highlights fine prospect for CS to reconstruct collagen-mineralized tissues as a natural material.

Glutaraldehyde-induced remineralization improves the mechanical properties and biostability of dentin collagen.

The purpose of this study was to induce a biomimetic remineralization process by using glutaraldehyde (GA) to reconstruct the mechanical properties and biostability of demineralized collagen. Demineralized dentin disks (35% phosphoric acid, 10s) were pretreated with a 5% GA solution for 3min and then cultivated in a calcium phosphate remineralization solution. The remineralization kinetics and superstructure of the remineralization layer were evaluated by Raman spectroscopy, transmission electron microscopy, scanning electron microscopy and nanoindentation tests. The biostability was examined by enzymatic degradation experiments. A significant difference was found in dentin remineralization process between dentin with and without GA pretreating. GA showed a specific affinity to dentin collagen resulting in the formation of a cross-linking superstructure. GA pretreating could remarkably shorten remineralization time from 7days to 2days. The GA-induced remineralized collagen fibrils were well encapsulated by newly formed hydroxyapatite mineral nanocrystals. With the nano-hydroxyapatite coating, both the mechanical properties (elastic modulus and hardness) and the biostability against enzymatic degradation of the collagen were significantly enhanced, matching those of natural dentin. The results indicated that GA cross-linking of dentin collagen could promote dentin biomimetic remineralization, resulting in an improved mechanical properties and biostability. It may provide a promising tissue-engineering technology for dentin repair.

Hierarchical structure and mechanical properties of remineralized dentin.

It is widely accepted that the mechanical properties of dentin are significantly determined by its hierarchical structure. The current correlation between the mechanical properties and the hierarchical structure was mainly established by studying altered forms of dentin, which limits the potential outcome of the research. In this study, dentins with three different hierarchical structures were obtained via two different remineralization procedures and at different remineralization stages: (1) a dentin structure with amorphous minerals incorporated into the collagen fibrils, (2) a dentin with crystallized nanominerals incorporated into the collagen fibrils, and (3) a dentin with an out-of-order mineral layer filling the collagen fibrils matrix. Nanoindentation tests were performed to investigate the mechanical behavior of the remineralized dentin slides. The results showed that the incorporation of the crystallized nanominerals into the acid-etched demineralized organic fibrils resulted in a remarkable improvement of the mechanical properties of the dentin. In contrast, for the other two structures, i.e. the amorphous minerals inside the collagen fibrils and the out-of-order mineral layer within the collagen fibrils matrix, the excellent mechanical properties of dentin could not be restored.

Biomimetic promotion of dentin remineralization using l-glutamic acid: inspiration from biomineralization proteins.

The amorphous phase precipitates first during biomineralization and acts as the precursor for the subsequent mineralization of hard tissues including dentin. During this process, various biomineralization proteins with different, even opposite functions control the dimensions and phase states of the amorphous precursors that permeate the collagen matrix and then crystallize to form highly sophisticated organic-inorganic biological materials. In this study, a biomimetic strategy containing polyacylic acid and l-glutamic acid (l-Glu) was applied to promote the remineralization of Ca-depleted dentin collagen. Following the structural features of biomineralization-related non-collagenous proteins (NCPs), l-Glu was found to be capable of promoting the crystallization kinetics of the polyacylic acid-stabilized metastable amorphous to hydroxyapatite phase transformation. It is demonstrated that the dentin remineralization could be shortened within two days by using the cooperative effect of polyacrylic acid and l-glutamic acid. Furthermore, the resulting remineralized dentin layer has the same characteristics, including mechanical strength, as the natural ones. This biomimetic strategy highlights the combination of the two opposing factors of biomineralization components as the key to control the phase-transformation-based mineralization reactions with the organic matrix of dental tissues. In summary, a bio-inspired approach was followed to reconstruct collagen-mineralized tissues with biocompatible functions, morphologies, and characteristics.

Prosthodontic rehabilitation of malpositioned implants after ameloblastoma followed by mandibulectomy and costal bone graft: a clinical report.

This clinical report describes the rehabilitation with costal bone graft reconstruction and 3 implants of a patient with a partial mandibular defect as a result of a partial mandibulectomy due to ameloblastoma of the left mandible. Due to the altered shape of the graft bone, the implants were malpositioned in the buccolingual plane. The prosthodontic rehabilitation was successfully completed by using an implant-supported milled bar combined with telescopic crown-retained dentures. This tooth implant-supported prosthesis successfully restored function and esthetics. Aspects that deal with the repair of the buccal soft tissues are discussed.

[Effect of different irrigants on radicular dentin cleansing and resin tag formation after post space preparation].

OBJECTIVE: To evaluate the effect of different root canal irrigants on smear layer removal and dentinal tubule opening of root canal surfaces after post space preparation. METHODS: Thirty maxillary anteriors were endodontically treated. After post space preparation, the teeth were assigned to three groups with ten teeth each: group A, B, C. 3% H2O2, 15% ethylenediamine tetraacetic acid(EDTA), 15% EDTA and 3% NaClO were used as irrigant of group A, B, C. After post space irrigation, eight teeth of each group were examined under scanning electron microscope (SEM) for smear layer removal and dentinal tubule opening. The left two specimens were restored with fiber posts and prepared for evaluation of resin tag formation. RESULTS: The cleansing effectiveness of group A, B and C was respectively 3.89 +/- 0.36, 1.77 +/- 0.30, 1.25 +/- 0.21. The dentinal tubule opening of group A, B and C was respectively (2.53 +/- 0.19), (3 11 +/- 023) (3.83 +/- 0.52) microm. The cleansing effectiveness and dentinal tubule opening of root canal surfaces were significantly affected by different root canal irrigants (P < 0.05). Excessive erosion of the dentin was observed in group C. Resin tag formation differed between the three irrigant groups, and group B showed excellent resin tag formation. CONCLUSION: Irrigation with 15% EDTA after post space preparation can excellently remove the smear layer and improve dentinal tubule opening, permitting well penetration of resin adhesive into the dentinal tubules and collagen fibrillar structure.

Does endodontic post space irrigation affect smear layer removal and bonding effectiveness?

The effect of different post space irrigants on smear layer removal and dentin bond strength was evaluated. Sixty-six extracted sound maxillary central incisors were endodontically treated. After post space preparation, the teeth were assigned to three groups of 22 teeth each. The teeth of these three groups were irrigated for 1 min with 17% ethylenediaminetetracetic acid (EDTA) (group 1), 5.25% sodium hypochlorite (NaOCl) (group 2), or 0.9% sodium chloride (NaCl) (group 3). In each group, eight specimens were split longitudinally for smear layer evaluation, and the other fourteen specimens were filled with a self-etching adhesive system (Panavia F). Four of 14 specimens of each group were prepared for evaluation of the resin-dentin interdiffusion zone (RDIZ) and resin tags, and the other 10 specimens were serially sectioned for push-out test analysis. Smear layer removal and bond strength were affected by different post space irrigants. EDTA removed the smear layer extremely effectively and, as a result, improved the bond strength at each region (apical, middle, and coronal) of the roots. Resin tag formation and the RDIZ were also affected by different irrigants and in accordance with bond strength. Therefore, removal of the smear layer use a self-etching luting system plays an important role in bonding effectiveness.

Effect of different irrigation on smear layer removal after post space preparation.

The purpose of this study was to evaluate the effect of different irrigating solutions on smear layer removal and dentinal tubule opening on root canal surfaces after post space preparation and to study whether additional ultrasonic irrigation has any effect on smear layer removal. Forty-eight anterior teeth were treated endodontically. After post space preparation, they were assigned to six groups: group 1, EDTA; group 2, EDTA with ultrasonic activation; group 3, sodium hypochlorite (NaOCl); group 4, NaOCl with ultrasonic activation; group 5, sodium chloride (NaCl); and group 6, NaCl with ultrasonic activation. Specimens were examined under a field-emission scanning electron microscope and scored for debris removal and dentinal tubule opening at the coronal, middle, and apical thirds of the root canal. The results showed that EDTA performed significantly better than NaCl and NaOCl in smear layer removal and dentinal tubule opening. Additional ultrasonic irrigation did not improve smear layer removal significantly.