An integrative-omics analysis of an industrial clavulanic acid-overproducing Streptomyces clavuligerus.

Clavulanic acid (CA) is a clinically important secondary metabolite used to treat infectious diseases. We aimed to decipher complex regulatory mechanisms acting in CA biosynthesis by analyzing transcriptome- and proteome-wide alterations in an industrial CA overproducer Streptomyces clavuligerus strain, namely DEPA and its wild-type counterpart NRRL3585. A total of 924 differentially expressed genes (DEGs) and 271 differentially produced proteins (DPPs) were obtained by RNA-seq and nanoLC-MS/MS analyses, respectively. In particular, CA biosynthetic genes, namely, car (cad), cas2, oat2, pah, bls, ceas2, orf12, and claR, a cluster situated regulatory (CSR) gene, were significantly upregulated as shown by RNA-seq. Enzymes of clavam biosynthesis were downregulated considerably in the DEPA strain, while the genes involved in the arginine biosynthesis, one of the precursors of CA pathway, were overexpressed. However, the biosynthesis of the other CA precursor, glyceraldehyde-3-phosphate (G3P), was not affected. CA overproduction in the DEPA strain was correlated with BldD, BldG, BldM, and BldN (AdsA) overrepresentation. In addition, TetR, WhiB, and Xre family transcriptional regulators were shown to be significantly overrepresented. Several uncharacterized/unknown proteins differentially expressed in the DEPA strain await further studies for functional characterization. Correlation analysis indicated an acceptable degree of consistency between the transcriptome and proteome data. The study represents the first integrative-omics analysis in a CA overproducer S. clavuligerus strain, providing insights into the critical control points and potential rational engineering targets for a purposeful increase of CA yields in strain improvement. KEY POINTS: ∙ Transcriptome and proteome-wide alterations in industrial CA overproducer strain DEPA ∙ An acceptable degree of consistency between the transcriptome and proteome data ∙ New targets to be exploited for rational engineering.

The effect of artificial accelerated aging on the color stability, microhardness, and surface roughness of different dental laminate veneer materials.

OBJECTIVE: This study aimed to evaluate the effect of artificial accelerated aging (AAA) on color stability, surface roughness, and microhardness of three laminate veneer (LV) materials. MATERIALS AND METHODS: Specimens of ceramic LV (CLV-IPS E.max Press), hand-layered composite LV (hand-layered laminate veneer [HLV]-Tetric N-Ceram), and prefabricated composite LV (prefabricated laminate veneer [PLV]-Componeer Coltene) were prepared as discs (n = 10). CIE L*, a*, and b* color coordinates, the Vickers microhardness, and surface roughness were measured 24 hours after preparation and reevaluated after aging for 300 hours in an ultraviolet (UV)-AAA system (Ci35 Weather-Ometer). Color difference (CIEDE2000 [ΔE00 ]) was calculated. Data were statistically analyzed with the Shapiro-Wilk test and the Kruskall-Wallis test followed by the Mann-Whitney U tests (α = .05). RESULTS: All of the LV groups showed significant differences in ΔE00 after AAA (P < .001). Comparing the color changes of the HLVs with the PLVs, no significant difference could be found (P = .705). There was a statistically significant difference in the means of changes in microhardness among the LVs materials (P < .001). The changes in surface roughness results showed a significant difference after AAA in all the LVs (P < .001). CONCLUSIONS: Within the limitations of this in vitro study, the color stability, the microhardness, and surface roughness of tested LVs were influenced by AAA. CLINICAL SIGNIFICANCE: The prefabricated composite LV system does not replace the individualized ceramic LV technique, but rather offers an alternative to hand-layered LVs, which is delicate and time-consuming technique.

Temperature rise in pulp and gel during laser-activated bleaching: in vitro.

The aim of this study was to evaluate the increase in temperature induced by various light sources during in-office bleaching treatment, under simulated blood microcirculation in pulp conditions. Ten freshly extracted human maxillary central incisors were used for the study. The roots of the teeth were removed from approximately 2 mm below the cementoenamel junction and fixed on an apparatus for the simulation of blood microcirculation in pulp. A J-type thermocouple wire was inserted into the pulp chamber through an artificial access at the lingual surfaces of the teeth, and another thermocouple wire was fixed on the labial surface of the teeth meanwhile. An in-office bleaching agent, intense red in color and with 30% water content, was applied to the labial surfaces of the teeth, and repeating measurements were made for each tooth using three different light sources: Er:YAG laser (40 mJ, 10 Hz, 20 s), 810-nm diode laser (4 W, 20 s, CW), and high-intensity light-emitting diodes (LED) (1,100 mW/cm(2), 20 s) as the control. Temperature increase in the pulp chamber and within the bleaching gel during light application were recorded and statistically evaluated. The highest pulp temperature increases were recorded for the diode laser group (2.61 °C), followed by the Er:YAG laser (1.86 °C) and LED (1.02 °C) groups (p < 0.05; analysis of variance (ANOVA), Tukey's honestly significant difference (HSD)). Contradictorily, the lowest gel temperature increases were recorded for diode laser (6.21 °C) and followed by LED (12.38 °C) and Er:YAG (20.11 °C) groups (p < 0.05; ANOVA, Tukey's HSD). Despite the significant differences among the groups, the temperature increases recorded for all groups were below the critical value of 5.6 °C that can cause irreversible harmful changes in pulp tissue. It can be concluded that, with regard to temperature increase, all the light sources evaluated in this study can be used safely for in-office bleaching treatment within the described parameters.

Effect of the number of supporting implants on mandibular photoelastic models with different implant-retained overdenture designs.

PURPOSE: The purpose of the study was to evaluate the effect of the number of supporting implants and different retentive mechanisms on load transfer characteristics of mandibular overdentures. MATERIALS AND METHODS: Two photoelastic models of edentulous mandibles were fabricated having two and four cylindrical implants (Calcitek, 4 × 13 mm) embedded in the parasymphyseal area. Four attachment systems were evaluated: single anchor attachment (ERA), bar-clip, bar with distally placed ball attachments, and bar with distally placed extracoronal rigid attachments (Easy Slot). A 133 N vertical force was applied unilaterally to the central fossa of the right first molar. The resulting stresses of the models were observed and recorded photographically in the field of a circular polariscope. RESULTS: The highest stresses were observed with the bar with distally placed extracoronal rigid attachment (Easy Slot) design, followed by bar-ball, bar, and the single anchor attachment (ERA) for both models. The lowest stress was observed with the single anchor attachment (ERA) design for both models. There were slight differences in stress values around implants in both models. CONCLUSIONS: For all tested attachments on both models, the stress was concentrated on the ipsilateral implant. The bar-clip system allowed the distribution of load to all supporting implants in both models. Although the highest stress level observed with all attachment systems was moderate, the bar-Easy Slot attachment showed the highest stresses. The lowest stress was observed with the single anchor attachment (ERA) design for both models. Varying the number of implants had no significant effect on stress values around supporting implants.

Evaluation of the efficacy of mandibular conventional and implant prostheses in a group of Turkish patients: a quality of life study.

PURPOSE: The aim of this study was to compare the satisfaction and quality of life (QoL) in a group of patients using mandibular complete dentures, implant-retained overdentures, removable partial dentures (RPDs), or implant-supported fixed partial dentures (FPDs). MATERIALS AND METHODS: A total of 116 patients (aged 36 to 81, mean age 58 ± 10.03 years) were assigned to four groups (n = 29) and treated with mandibular implant-retained overdentures, implant-supported FPDs (two implants/three unit FPDs), conventional complete dentures, or RPDs. The groups were well matched in terms of gender, age, and the edentulous period. All patients had edentulous maxillary arches and completely or partially edentulous mandibles. All prostheses were mandibular prostheses. The OHIP-14, OHQoL-UK, and SF-36 surveys were used to determine QoL before implant surgery and 1 year after prosthetic treatment. RESULTS: The baseline and 1-year data from 116 patients were analyzed. A significant improvement was found among the QoL scales for all groups (p < 0.05). The most significant improvement was found in the implant-retained overdenture group (15.67 ± 2.47), while the least improvement was found among the implant-supported FPD group (5.14 ± 2.08). The SF-36 test revealed no differences between the before and after treatment scores for general health, pain, vitality, social function, and physical function difficulties (p > 0.05). The only significant difference was found for mental health (p = 0.011). CONCLUSION: A positive influence on oral health-related QoL was observed in all groups. The QoL values were the most improved in the implant-retained overdenture group.

Two formulations of coronavirus disease-19 recombinant subunit vaccine candidate made up of S1 fragment protein P1, S2 fragment protein P2, and nucleocapsid protein elicit strong immunogenicity in mice.

INTRODUCTION: Coronavirus disease (COVID-19) is ongoing as a global epidemic and there is still a need to develop much safer and more effective new vaccines that can also be easily adapted to important variants of the pathogen. In the present study in this direction, we developed a new COVID-19 vaccine, composed of two critical antigenic fragments of the S1 and S2 region of severe acute respiratory syndrome coronavirus 2 as well as the whole nucleocapsid protein (N), which was formulated with either alum or alum plus monophosphoryl lipid A (MPLA) adjuvant combinations. METHODS: From within the spike protein S1 region, a fragmented protein P1 (MW:33 kDa) which includes the receptor-binding domain (RBD), another fragment protein P2 (MW:17.6) which contains important antigenic epitopes within the spike protein S2 region, and N protein (MW:46 kDa) were obtained after recombinant expression of the corresponding gene regions in Escherichia coli BL21. For use in immunization studies, three proteins were adsorbed with aluminum hydroxide gel and with the combination of aluminum hydroxide gel plus MPLA. RESULTS: Each of the three protein antigens produced strong reactions in enzyme-linked immunosorbent assays and Western blot analysis studies performed with convalescent COVID-19 patient sera. In mice, these combined protein vaccine candidates elicited high titer anti-P1, anti-P2, and anti-N IgG and IgG2a responses. These also induced highly neutralizing antibodies and elicited significant cell-mediated immunity as demonstrated by enhanced antigen-specific levels of interferon-γ (INF-γ) in the splenocytes of immunized mice. CONCLUSION: The results of this study showed that formulations of the three proteins with Alum or Alum + MPLA are effective in terms of humoral and cellular responses. However, since the Alum + MPLA formulation appears to be superior in Th1 response, this vaccine candidate may be recommended mainly for the elderly and immunocompromised individuals. We also believe that the alum-only formulation will provide great benefits for adults, young adolescents, and children.

The effect of ceramic thickness and number of firings on the color of two all-ceramic systems.

STATEMENT OF PROBLEM: All-ceramic restorations have been advocated for superior esthetics, and various materials have been used to improve ceramic core strength, but there is a lack of information on how color is affected by different core substructures and fabrication procedures. PURPOSE: The purpose of this study was to evaluate the effects of various dentin ceramic thicknesses and repeated firings on the color of lithium disilicate glass-ceramic (IPS e.max Press) and zirconium-oxide (DC-Zirkon) all-ceramic systems. MATERIAL AND METHODS: Thirty disc-shaped specimens, 4 mm in diameter with a 1-mm core thickness, and 0.5-, 1-, or 1.5-mm dentin ceramic thicknesses, were made from each of 2 ceramic systems (n=10). Repeated firings (3, 5, 7, or 9) were performed, and the color of the specimens was compared with the color after the initial firing. Color differences among ceramic specimens were measured using a spectrophotometer (VITA Easyshade), and data were expressed in CIELAB system coordinates. Repeated measures ANOVA was used to analyze the data (number of firings, ceramic composition, and ceramic thickness) for significant differences. The Tukey HSD test and paired 2-tailed tests were used to perform multiple comparisons (alpha=.05). RESULTS: L*a*b* values of the ceramic systems were affected by the number of firings (3, 5, 7, or 9 firings) (P<.001), ceramic composition (DC-Zirkon or IPS e.max Press) (P<.001), and ceramic thickness (0.5, 1, or 1.5 mm) (P<.001). Significant interactions were present in L*a*b* values between the number of firings and ceramic composition (P<.001) and between the number of firings and ceramic thickness (P<.001). Significant interactions were present between the number of firings and ceramic thickness and ceramic composition (P<.05) in L* and b* values, but not for the a* value (P=.068). As the ceramic thickness increased, significant reductions in L* values (P<.01) were recorded for IPS e.max Press and DC-Zirkon specimens. For IPS e.max Press specimens, there were significant increases in a* and b* values (P<.01). For DC-Zirkon specimens, significant increases in a* values were observed; however, no significant differences were recorded for b* values. CONCLUSIONS: The analysis revealed that there were significant changes in L*a*b* color data as the number of firings increased, which resulted in perceptual color changes in L*a*b* color parameters.

Technical tips for constructing a maxillary implant-supported overdenture by using a double-impression technique.

Implant-supported overdentures have become a popular treatment option for completely edentulous patients. Functional loads should be optimally distributed to the mucosa and the abutments. This article describes a functional double-impression technique for fabricating a maxillary implant-supported overdenture.

Prosthetic solution for unfavorably inclined maxillary implants: a case report.

Misaligned implants may affect the esthetic, phonetic, and functional results and challenge the restorative dentist. Proper attachment selection is important considering the patient-related circumstances. This article presents a case where a change in prosthetic attachments was required because implant inclination diminished overdenture retention and stability. The treatment involved an alternative implant and soft-tissue impression technique.

Fabrication of a retrievable cement- and screw-retained implant-supported zirconium fixed partial denture: a case report.

It can be difficult to achieve superior esthetics in implant-supported fixed partial dentures (FPDs). Zirconia ceramics with high flexural strength and esthetic can be treatment options for implant-supported FPDs. This article describes a simple and reliable method to fabricate a retrievable cemented implant-supported zirconia FPD.

Technical tips for improved retention and stabilization of a unilateral removable partial denture.

An advantage of unilateral removable partial dentures (RPDs) is the lack of a major connector, but easy dislodgement of this design may cause several complications. Implant support of a unilateral RPD can provide additional stability and retention and may prevent such complications as aspiration or swallowing.

Fabrication of implant-assisted restorations utilizing functional impression techniques: case reports.

This article describes the fabrication of implant-supported overdentures and removable partial dentures attached to anterior fixed partial dentures utilizing impression techniques to transfer the position of implants and record soft tissue areas in a functional state.

Fabrication of a cement- and screw-retained multiunit implant restoration.

Retrieval of cemented implant restorations can be difficult for both the patient and the dentist. The method described in this article combines the advantages of cement- and screw-retained restorations. Abutment screws can be easily reached by the screw access channel prepared in the waxing phase; the restoration can be retrieved without destroying the implants and prosthesis. This article describes a simple and reliable method to fabricate a retrievable cemented prosthesis.

The effect of repeated firings on the color of an all-ceramic system with two different veneering porcelain shades.

STATEMENT OF PROBLEM: Color matching between a restoration and natural teeth is a common clinical problem. Despite careful shade selection, color of the restoration may be affected by fabrication procedures. PURPOSE: The purpose of this study was to determine the color changes of an all-ceramic restoration with 2 different veneering porcelain shades after repeated firings. MATERIAL AND METHODS: Twenty disc-shaped ceramic specimens, 4 mm in diameter with a 1-mm core thickness and 2 different veneering porcelain shades (A1, A3), were fabricated from a zirconia-based porcelain (DC-Zirkon) (n=10). Repeated firings (3, 5, 7, or 9 firings) were performed for the specimens, and color differences (DeltaE) were determined using a spectrophotometer. Repeated measures ANOVA was used to analyze the data (number of firings, veneering porcelain color). The Tukey HSD test and paired 2-tailed tests were performed for multiple comparisons (alpha=.05). RESULTS: The L*a*b* values of the ceramic system were affected by the number of firings (3, 5, 7, or 9) (P<.001) and the veneering porcelain shade (P<.001). Significant interactions were present between the number of firings and veneering porcelain shade for L* (P=.003) and b* (P=.042) values, but not for the a* value (P=.82). An increase in the number of firings of the specimens with both A1 and A3 veneering porcelain shades produced an increase in the L* value, resulting in lighter specimens (P<.001). For both A1 and A3 veneering porcelain shades, the a* value decreased after repeated firings, which resulted in more green specimens (P=.002). The b* value did not change after repeated firings (P=.09) for the A1 veneering porcelain shade; however, it increased for the A3 veneering porcelain shade, which resulted in more yellow specimens (P=.001). CONCLUSIONS: The color of the all-ceramic specimens with different veneering porcelain shades is influenced by repeated firings. However, color changes that occurred are clinically acceptable.

Photoelastic stress analysis of various retention mechanisms on 3-implant-retained mandibular overdentures.

STATEMENT OF PROBLEM: There are various stress transfer studies of 2- or 4-implant-retained mandibular overdenture designs. However, the influence of various types of attachments and implant inclination on stress distribution of 3-implant-retained mandibular overdenture designs has not been sufficiently assessed. PURPOSE: The purpose of this study was to compare the load transfer characteristics of 4 attachment systems for 3-implant-retained mandibular overdenture designs for vertically oriented and inclined implants. MATERIAL AND METHODS: Two photoelastic mandibular models were fabricated having 3 screw-type implants (3.7 x 14 mm with 4.8-mm diameter abutment platform) embedded in the interforaminal region. In the first model, the implants were parallel to each other and vertically oriented. In the second model, 1 implant in the midline was vertically oriented, and the other 2 implants were positioned 20 degrees divergent from the center implant. Four retention mechanisms were studied for each model--the Locator, Swissplus ball, Bredent bar, and Bredent bar-ball. The bar design connected the 3 implants, and the bar-ball design used the bar in a similar fashion but additionally incorporated distally placed ball attachments. A vertical force of 135 N was applied unilaterally to the central fossa of the right first molar. The resultant stresses that developed in the supporting structure were monitored photoelastically and recorded photographically. RESULTS: For the splinted and unsplinted 3-implant-retained overdenture designs evaluated, moderate and low level stresses were observed with different attachment systems. For both the vertically oriented and inclined implants, the bar-ball attachment system produced the lowest stress level. CONCLUSIONS: For vertical and inclined implant designs, lowest stress was transferred to all implants with the bar-ball attachment system, while moderate stresses were observed in implants on the loaded side with unsplinted attachment systems. The highest stress level observed with all attachment systems was moderate. For the vertical implant design, the observed stresses were distributed to all implants except with the ball attachment system, which demonstrated little discernible stresses on the non-loaded side implant.

Fabrication of a maxillary implant-supported overdenture retained by two cemented bars: a clinical report.

Parallel placement of 2 separate bars may be indicated in patients where bone is available in the posterior part of the maxilla. Bars and stud attachments are the primary attachment systems compatible with the majority of the implant systems currently available; however, treatment planning in certain situations may be challenging due to the component available with the implant system used. This report describes the fabrication of a cemented bar design for use in situations when the components of the implant system are inadequate for fabrication of a screw-retained bar.

Fabrication of a maxillary implant-supported removable partial denture: a clinical report.

Implant-supported removable partial denture treatment provides an esthetic and functional result that allows proper access for hygiene and maintenance. This article describes the treatment of a patient with a maxillary removable partial denture supported by 3 implants. The use of alignment-correction abutments enabled restoration of misaligned implants.