Refined 1.8 A structure of human aldose reductase complexed with the potent inhibitor zopolrestat.

As the action of aldose reductase (EC 1.1.1.21) is believed to be linked to the pathogenesis of diabetic complications affecting the nervous, renal, and visual systems, the development of therapeutic agents has attracted intense effort. We report the refined 1.8 A x-ray structure of the human holoenzyme complexed with zopolrestat, one of the most potent noncompetitive inhibitors. The zopolrestat fits snugly in the hydrophobic active site pocket and induces a hinge-flap motion of two peptide segments that closes the pocket. Excellent complementarity and affinity are achieved on inhibitor binding by the formation of 110 contacts (< or = 4 A) with 15 residues (10 hydrophobic), 13 with the NADPH coenzyme and 9 with four water molecules. The structure is key to understanding the mode of action of this class of inhibitors and for rational design of better therapeutics.     

The uptake of radioiodinated 5α-dihydrotestosterone by the prostate of intact and castrated rats

Radioiodinated steroid 2-¹²⁵I-dihydrotestosterone was prepared by direct labeling procedure and subsequently utilized in the distribution studies on Albino Wistar male rats. Maximum radioactivity in the prostate was found 3 h after the administration of the radiolabeled steroid to 24-h castrated animals (1.29%/g wet weight) and to intact rats (0.57%). The pretreatment of animals with dihydrotestosterone yielded lower uptake by the prostate (0.29%–0.30%), epididymis, and testis while it did not influence the distribution in other androgen-insensitive tissues. The carbon-iodine bond was proved to be intact in the radiopharmacon examined and in its metabolites when retained by the rat prostate. The reported results are in line with our previous investigations on in vitro binding of radioiodinated dihydrotestosterone to androgen receptors but indicate also little utility of the same label for the visualization of the prostate gland.     

Incorporation of Copper-Doped Mesoporous Bioactive Glass Nanospheres in Experimental Dental Composites: Chemical and Mechanical Characterization

Experimental dental resin composites incorporating copper-doped mesoporous bioactive glass nanospheres (Cu-MBGN) were designed to impart antibacterial and remineralizing properties. The study evaluated the influence of Cu-MBGN on the mechanical properties and photopolymerization of resin composites. Cu-MBGN were synthesized using a microemulsion-assisted sol–gel method. Increasing amounts of Cu-MBGN (0, 1, 5, and 10 wt %) were added to the organic polymer matrix with inert glass micro- and nanofillers while maintaining a constant resin/filler ratio. Six tests were performed: X-ray diffraction, scanning electron microscopy, flexural strength (FS), flexural modulus (FM), Vickers microhardness (MH), and degree of conversion (DC). FS and MH of Cu-MBGN composites with silica fillers showed no deterioration with aging, with statistically similar results at 1 and 28 days. FM was not influenced by the addition of Cu-MBGN but was reduced for all tested materials after 28 days. The specimens with 1 and 5% Cu-MBGN had the highest FS, FM, MH, and DC values at 28 days, while controls with 45S5 bioactive glass had the lowest FM, FS, and MH. DC was high for all materials (83.7–93.0%). Cu-MBGN composites with silica have a potential for clinical implementation due to high DC and good mechanical properties with adequate resistance to aging.     

Tooth Storage,Dental Pulp Stem Cell Isolation,and Clinical Scale Expansion without Animal Serum

Introduction

Dental pulp stem cells (DPSCs) have therapeutic potential for dentin and dental pulp regeneration. For regenerative approaches to gain clinical acceptance, protocols are needed to determine feasible ways to store teeth, isolate DPSCs, and expand them to clinical scale numbers.

Methods

In this study, 32 third molars were obtained from patients and immediately placed in saline or tissue culture medium followed by overnight storage at 4°C or immediate isolation of DPSCs. Upon isolation, cells were expanded in medium containing either fetal bovine serum (FBS) or human serum (HS). Cell proliferation (population doubling time [PDT]), cell surface marker expression, and multipotency were compared between DPSCs in FBS and DPSCs in HS.

Results

The time frame of storage and storage medium did not affect the ability to isolate DPSCs. However, using HS instead of FBS in the initial isolation of DPSCs significantly decreased (P < .01) the isolation success rate from 89% (FBS) to 23% (HS). Yet, incorporating fibronectin in the DPSC initial isolation (using HS) significantly (P < .01) increased the isolation success rate to 83%. Interestingly, it was found that the proliferation rate was significantly (P < .05) higher for DPSCs in HS (PDT = 1.59 ± 0.46) than that for DPSCs in FBS (PDT = 2.84 ± 2.5). Finally, there was no difference in the expression of CD73, CD90, CD105, or multipotency (as measured by osteogenic, adipogenic, and chondrogenic differentiation) between DPSCs in FBS and DPSCs in HS.

Conclusions

These findings show a clinically feasible method of storing third molars for the isolation of DPSCs. Additionally, DPSCs can be isolated and expanded to clinical scale numbers in media devoid of FBS and still maintain their phenotypic properties.     

The efficiency of dentine adhesives in treating non-caries cervical lesions

The aim of this study was to prove the hypothesis that dentine adhesives can be used as therapeutic material in treating dentine hypersensitivity, regardless of aetiology. The research was conducted on 492 students of Zagreb University School of Dental Medicine (154 male, 338 female), 20-25-years-old. The defects of the tooth neck were found in 38 patients, on 133 teeth (38 of male patients, 95 of female) and dentine hypersensitivity was recorded according to the subjective sensations of patients. Therapeutic characteristics of three adhesive materials were examined simultaneously: All Bond 2, fourth generation adhesive, Syntac Single Component and One Step, fifth generation adhesives. Teeth treated with dentine lacquer Cervitec were used as a control group. Tooth necks were treated with selected materials according to instructions of a manufacturer. A completed statistical survey of the results has clearly shown that dentine adhesives can be used in symptomatic therapy of dentine hypersensitivity of the non-caries cervical lesions (NCCL). The survey has also shown that dentine adhesives of the fifth generation (Syntac Single Component and One Step) have much higher efficiency rate than dentine adhesives of the fourth generation (All Bond 2) and dentine lacquer (Cervitec). According to data complied through this study the conclusion can be brought forward that dentine adhesives are not a final solution to the problem of dentine hypersensitivity, because their efficiency decreases with time.     

Accounting for measurement reliability to improve the quality of inference in dental microhardness research: a worked example

Objectives

Dental microhardness experiments are influenced by unobserved factors related to the varying tooth characteristics that affect measurement reproducibility. This paper explores the appropriate analytical tools for modeling different sources of unobserved variability to reduce the biases encountered and increase the validity of microhardness studies.

Materials and methods

The enamel microhardness of human third molars was measured by Vickers diamond. The effects of five bleaching agents—10, 16, and 30 % carbamide peroxide, and 25 and 38 % hydrogen peroxide—were examined, as well as the effect of artificial saliva and amorphous calcium phosphate. To account for both between- and within-tooth heterogeneity in evaluating treatment effects, the statistical analysis was performed in the mixed-effects framework, which also included the appropriate weighting procedure to adjust for confounding. The results were compared to those of the standard ANOVA model usually applied.

Results

The weighted mixed-effects model produced the parameter estimates of different magnitude and significance than the standard ANOVA model. The results of the former model were more intuitive, with more precise estimates and better fit.

Conclusions

Confounding could seriously bias the study outcomes, highlighting the need for more robust statistical procedures in dental research that account for the measurement reliability. The presented framework is more flexible and informative than existing analytical techniques and may improve the quality of inference in dental research.

Clinical relevance

Reported results could be misleading if underlying heterogeneity of microhardness measurements is not taken into account. The confidence in treatment outcomes could be increased by applying the framework presented.

     

Light transmittance and polymerization kinetics of amorphous calcium phosphate composites

Clinical Oral Investigations - This study investigated light transmittance and polymerization kinetics of experimental remineralizing composite materials based on amorphous calcium phosphate (ACP),...     

Plasma osteocalcin values and related hormonal parameters in patients subjected to a variety of prostate anticancer agents

Summary Circulating osteocalcin (OC) and cortisol levels were measured in blood samples from 93 patients with dissaminated prostate cancer. Among these subjects 79 had not responsed to therapy, while 14 had responded to a variety of anticancer treatment strategies (orchiectomy, cyproterone acetate (CPA), flutamide, Buserelin, diethylstilbestrol (DES), Estracyt, and polyestradiol phosphate). The control group consisted of 19 patients with benign prostatic hypertrophy. In the majority of these patients blood adrenocorticotropic hormone (ACTH), estradiol human growth hormone (hGH), and thyroid stimulating hormone (TSH) levels were also assessed. In nonresponders to therapy with DES and Estracyt subnormal circulating OC levels were measured, while normal OC values were found in nonresponders to other treatment strategies. In patient given Estracyt highly elevated estradiol levels were recorded. Subnormal and/or low-normal estradiol concentrations were found in patients subjected to CPA and DES. Elevated blood cortisol levels were assessed in subjects treated with DES and Estracyt while at the same time either subnormal and low-normal plasma ACTH concentrations were measured in these same patients. Accordingly, the decline observed in OC concentration seems to be a consequence of the well-established inhibitory effect of glucorticoids on osteoblast activity. The decline in blood cortisol levels obtained after administration of dexamethasone in patients given DES and Estracyt may be attributed both to possible changes in catabolic pathways and to the contribution of the negative neuroendocrinological feedback.     

Effect of Conventional Adhesive Application or Co-Curing Technique on Dentin Bond Strength

The aim of this in vitro study was to assess the effect of two different adhesive application methods on shear dentin bond strength (ISO 29022) using three various adhesive systems. A mid-coronal section of 77 intact third human molars with fully developed apices was made to create flat bonding substrates. The materials used in the study were Excite F (Ivoclar Vivadent), Prime&Bond Universal (Dentsply Sirona) and G-Premio Bond (GC). The application of each adhesion system was performed in two different ways. In the first group, the bonding agent was light cured immediately after the application (conventional method), while in the second group the adhesive and composite were cured concurrently (“co-curing” method). A total of 180 specimens were prepared (3 adhesives × 2 method of application × 30 specimens per experimental group), stored at 37 °C in distilled water and fractured in shear mode after 1 week. Statistical analysis was performed using ANOVA and Weibull statistics. The highest bond strength was obtained for Prime&Bond conventional (21.7 MPa), whilst the lowest bond strength was observed when co-curing was used (particularly, Excite F 12.2 MPa). The results showed a significant difference between conventional and co-curing methods in all materials. According to reliability analysis, the co-curing method diminished bond reliability. Different application techniques exhibit different bond strengths to dentin.