Persistent and recurrent skin infection with small-colony variant methicillin-resistant Staphylococcus aureus

S. aureus is one of the problematic bacteria, capable to develop resistance mechanisms to all antibiotics that the bacteria are naturally susceptible. A particular phenotypic mechanism, especially against the antibiotics that repressed the synthesis of the cellular wall and aminoglycosides, was evidenced in subpopulations that grows in small-colonies and represents auxotrophic mutants for hemin, menadione or thymidine. This type of strains has been isolated most frequently from patients with osteomyelitis, septic arthritis or pulmonary infections after a long period of antibiotic treatment. The authors present the case of a patient with persistent and recurrent staphylococcal infection of the peritoneal dialysis exit site, treated with different antibiotics (ciprofloxacin, vancomycin, amoxicillin and clavulanic acid, cephalexin) from witch has been isolated a small-colony strain of methicillin-resistant S. aureus. Therapeutic failure can be explain by the slow multiplication of this strain in vivo, persistence into phagocytes and the protection offered by biofilm from the surface of the catheter. Bacteriologic diagnosis in these cases is difficult because of the culture, biochemical and susceptibility testing particularities of these strains. All these may lead failure to identification small colony variants of S. aureus and mis-evaluation of the frequency of infection with these strains in patients with long-term antibiotherapy.     

Associations between smoking, polymorphisms in polycyclic aromatic hydrocarbon (PAH) metabolism and conjugation genes and PAH-DNA adducts in prostate tumors differ by race.

Polycyclic aromatic hydrocarbon (PAH)-DNA adducts may induce mutations that contribute to carcinogenesis. We evaluated potential associations between smoking and polymorphisms in PAH metabolism [CYP1A1 Ile 462Val, CYP1B1 Ala 119Ser and Leu 432Val, microsomal epoxide hydrolase (mEH) Tyr 113His and His139Arg, CYP3A4 A(-392)G] and conjugation [glutathione S-transferase (GST) M1 null deletion, GSTP1 Ile 105Val] genes and PAH-DNA adduct levels (measured by immunohistochemistry) in tumor and nontumor prostate cells in 400 prostate cancer cases. Although no statistically significant associations were observed in the total sample, stratification by ethnicity revealed that Caucasian ever smokers compared with nonsmokers had higher adduct levels in tumor cells (mean staining intensity in absorbance units +/- SE, 0.1748 +/- 0.0052 versus 0.1507 +/- 0.0070; P = 0.006), and Caucasians carrying two mEH 139Arg compared with two 139His alleles had lower adducts in tumor (0.1320 +/- 0.0129 versus 0.1714 +/- 0.0059; P = 0.006) and nontumor (0.1856 +/- 0.0184 versus 0.2291 +/- 0.0085; P = 0.03) cells. African Americans with two CYP1B1 432Val compared with two 432Ile alleles had lower adducts in tumor cells (0.1600 +/- 0.0060 versus 0.1970 +/- 0.0153; P = 0.03). After adjusting for smoking status, carrying the putative "high-risk" genotype combination, the faster metabolism of PAH-epoxides to PAH-diol-epoxides (CYP1B1 432Val/Val and mEH 139Arg/Arg) with lower PAH-diol-epoxide conjugation (GSTP1 (105)Ile/Ile), was associated with increased adducts only in Caucasian nontumor cells (0.2363 +/- 0.0132 versus 0.1920 +/- 0.0157; P= 0.05). We present evidence, for the first time in human prostate that the association between smoking and PAH-DNA adducts differs by race and is modified by common genetic variants.     

Malignant non-Hodgkin's lymphoma (NHL) of the jaws: A review of 16 cases

Non-Hodgkin's lymphoma (NHL) is rarely found in the jaw. We present 16 cases and the purpose of this study was to analyze the clinical signs and symptoms. The treatment and the progression evolution are also mentioned. The diagnosis was usually difficult and was often misleading and so delays before the first bone biopsy were frequent. The therapy of this rare, diffuse, large cell lymphoma was very variable from one case to another but the majority of the patients were treated with a combination of chemotherapy and radiotherapy.     

Macro-, micro- and nano-mechanical investigations on silorane and methacrylate-based composites

ObjectivesCationic ring-opening monomers with a reduced shrinkage stress – silorane – are being used as matrix resins for recently introduced dental composites. Since shrinkage and mechanical properties are generally opposite properties, our study aimed to analyze the mechanical behavior of the silorane-based composite in comparison to six homologous clinical successful methacrylate-based composites.MethodsMechanical properties were determined at macro- (strength and modulus of elasticity), micro- (hardness, modulus of elasticity and creep) and nano-scale (nano-dynamic-mechanical parameters: complex, storage, loss modulus and tan δ) after storing the materials for 24 h in distilled water as well as after aging (thermocycling and storing for 4 weeks in water, saliva or alcohol).ResultsThe strongest influence on the mechanical properties at macroscopic scale was exerted by the storage media although the influence of the material was also significant. At micro- and nano-scale, the material itself influenced the mechanical properties stronger than the storage. By comparing the four storage conditions, a multivariate analysis revealed a significant decrease in all measured mechanical properties by storing for 4 weeks in water, saliva or alcohol, when compared to the 24 h storage. The strongest effect was exerted through the alcohol storage, whereas the effect of storing for 4 weeks in water or saliva was comparable. The nano-composites were more degraded by a 4-week storage in water and saliva than the micro-hydrids, whereas the effect of storing in alcohol was material depended.The tested silorane-based composite revealed good mechanical properties. The material was very stable in all applied solvents and more reliable by storing in alcohol solutions than the measured methacrylate-based composites.SignificanceFrom the point of view of the mechanical properties measured at macro-, micro- and nano-scale, the silorane-based composite was comparable to clinically successful methacrylate-based composite materials, encouraging the clinical use of the new composite material.     

Long-term oncological outcome in patients with cervical cancer after 3 trimodality treatment (radiotherapy,platinum-based chemotherapy,and robotic surgery)

Cervical cancer represents a general health issue spread all over the globe, which prompts the surge of scientific survey toward the rise of survival and condition of life of these patients. American and European guidelines suggest the open surgery, laparoscopic, and robotic surgery are the main therapeutic approaches for radical hysterectomy for patients with cervical cancer. This is the first survey to analyze the long-term oncological outcome of an extensive series of subjects cared for with multimodality treatment, here comprising robotic surgery.This study intents to evaluate the long-term oncological result in patients diagnosed with cervical cancer treated with radiotherapy (±chemotherapy) and robotic surgery compared with open surgery. Medical files of 56 patients diagnosed with cervical cancer who underwent a robotic hysterectomy and radiotherapy ± chemotherapy were retrospectively analyzed.The median age at diagnosis was 50.5 (range: 23–70). Eleven patients (19.6%) presented in an early stage (IB–IIA) and 80.4% advanced stage (IIB–IVA). Overall response rate after radiotherapy and chemoradiotherapy was 96.2%. Pathologic complete response was obtained in 64% of patients. After a median follow-up of 60 months (range: 6–105 months), 8 patients (14.2%) presented local recurrence or distant metastases. Disease-free survival (DFS) was 92% at 2 years and 84% at 3 and 5 years. Overall survival (OS) rates at 2, 3, and 5 years for patients with robotic surgery were 91%, 78%, and 73%, median OS not reached. OS was lower in the arm of open surgery (2, 3, and 5 years 87%, 71%, and 61%, respectively; median OS was 72 months P = .054). The multivariate analysis regarding the outcome of patients revealed an advantage for complete versus partial response (P < .002), for early versus advanced stages (P = .014) and a 10% gained in DFS at 3 years for patients in whom chemoradiotherapy was administered (DFS at 3 years 75% vs 85%) in patients with advanced stages.Robotic surgery has a favorable oncological outcome when associated with multimodal therapy.     

Fracture toughness of dental restorative materials

The ability of a restorative material to withstand fracture is of crucial importance especially in stress-bearing area. Therefore, the study aims to analyse the fracture toughness of a large number of dental restorative materials categories. The fracture toughness (K _IC ) of 69 restorative materials belonging to ten materials categories—micro-hybrid, nanofilled, microfilled, packable, ormocer-based, and flowable resin-based composites (RBC), compomers and flowable compomers, as well as glass ionomer cements (GIC) and resin-modified GIC was measured by means of the single-edge notched-beam method after storing the samples (n = 8) for 24 h in distilled water. Data were analyzed with the one-way analysis of variance (ANOVA) followed by the Tukey’s test and partial eta-squared statistics (p < 0.05). Large variations between the tested materials within a material category were found. The lowest fracture toughness was reached in the GIC group, followed by the microfilled RBCs, resin-modified GIC, and flowable compomers, which do not differ significantly among each other as a material group. The ormocer-based, packable, and micro-hybrid RBCs performed statistically similar, reaching the highest fracture toughness values. Between the two categories of flowables—composites and compomers—no differences were measured. The correlation between K _IC and filler volume (0.34) and respective filler weight (0.40) was low. K _IC increased with the volume fraction of fillers until a critical value of 57%, following with a plateau, with constant values until ca. 65% volume fraction. Above this value, K _IC decreased slightly. Due to the very large variability of the fracture toughness within a material type, the selection of a suitable restorative material should have not been done with respect to a specific material category, especially in stress-bearing areas, but by considering the individual measured material properties.     

The effect of aging on the mechanical properties of nanohybrid composites based on new monomer formulations

Objectives

Nanohybrid resin-based composites (RBCs) containing new types of matrix monomers such as dimer acid-based dimethacrylate or tricyclodecane-urethane are assumed to show decreased water uptake and therefore better resistance to hydrolytic degradation than RBCs using bisphenol A diglycidyl methacrylate (BisGMA) due to their hydropobic nature. Our study aimed to analyze the effect of aging on six nanohybrid RBCs, of which two are using these new types of monomers, with regard to differences in the mechanical properties of the materials.

Materials and methods

Diametral tensile strength (DTS), Vickers hardness (HV), and creep were measured. Mechanical tests were performed after storing samples for 24 h in distilled water, as well as after aging (thermocycling for 5,000 cycles at 5–55°C and storage for 4 weeks either in distilled water, artificial saliva, or ethanol).

Results

The effect of aging on all test parameters was lower than the effect of the material. This information was provided by a general linear model, showing higher partial η² values for the influence factor material than for the factor aging. The influence of aging on the micromechanical properties HV and creep was proven to be more sensitive than on the macromechanical property (DTS). This was also illustrated by lower η² values for the variable aging for DTS. An increase of the creep of all materials was observed after storage in alcohol.

Conclusions

The use of new types of monomers could not be shown to be a significant advantage to the other examined materials containing BisGMA.

Clinical relevance

Nanohybrid composites can be recommended as universal filling materials, whether based on new or conventional monomers.     

Investigations towards nano-hybrid resin-based composites

Objective

Clinical data indicate an increased trend in material fracture as reason for failure in composite restorations, questioning whether modern resin-based composites (RBCs) are able to fulfil the rising aesthetical demands and to provide at the same time a sufficient mechanical stability also in larger cavities. Nano-hybrid RBCs are promoted as materials with improved mechanical properties. The aim of this study was to analyse differences in mechanical properties within and between modern flowable and non-flowable nano-hybrid and micro-hybrid RBCs by measuring mechanical properties at macro- and micro-scale.

Methods

Thirty-four RBCs with traditional and new monomer formulation or photo-polymerization initiator technology—15 nano-hybrid, nine micro-hybrid and ten flowable—were therefore considered. Flexural strength, flexural modulus (E_flexural), indentation modulus, Vickers hardness (HV) and creep were measured after the samples had been stored in water for 24 h at 37°C. Differences within the materials as well as within material categories were statistically analysed using one-way ANOVA with Tukey HSD post hoc test (α?=?0.05) as well as partial eta-square statistics.

Results

The category of micro- and nano-hybrid RBCs performed in all properties superior compared to the flowable RBCs. The former two categories differ significantly only with regard to three parameters, with nano-hybrid RBCs showing higher HV respectively lower E_flexural and filler weight. The micro-mechanical parameters proved to be more sensitive to differences in filler amount and RBCs type than the macro-mechanical properties.

Clinical relevance

Only few differences were found between nano-hybrid and micro-hybrid RBCs as a material category and thus, from laboratory tests, no clear advantages in the mechanical stability in stress-bearing areas of nano-hybrid RBCs are expected clinically. Similar is valid for materials with new monomer formulation or photo-polymerization initiator technology. However, several of the measured nano-hybrid RBCs showed consistently higher mechanical properties than the mean values of the micro-hybrid RBCs.     

Effect of polymerisation and ageing on the incremental bond strength of ormocer-based dental materials

Objective

The aim of this study was to investigate the effect of polymerisation and ageing on the incremental bond strength (IBS) and fracture mechanics of experimental and commercial, well established ormocer-based materials.

Methods

An experimental dimethacrylate-diluent-free ormocer was compared with two commercial products (Admira (VOCO); Ceram X Duo (Dentsply)). For Ceram X Duo, the strength between dentin shades (DD) and between dentin and enamel shades (DE) was measured. In order to simulate clinical conditions, when a direct access to the composite surface is impeded, the curing unit was applied at different distances (1, 3 or 6 mm) from the sample's surface. IBS was measured after the samples were stored in distilled water (24 h/37 °C) and after ageing (5,000 cycles between 5 and 55 °C followed by storage (28 days/37 °C) in distilled water). Additionally, the degree of cure (DC) was measured in a thin film (~50 μm). A multivariate analysis, an additional one-way ANOVA with Tukey HSD post hoc test (α?=?0.05), an independent t test (α?=?0.05), and Weibull statistics were used to assess the results.

Results

After 24 h, the values for IBS were statistically the same. Differences revealed after ageing, whereby the experimental material achieved the significant highest and Admira the lowest results. By evaluating after 24 h and after ageing, the experimental material obtained the smallest Weibull modulus “m”. The predominant breaking mechanism is cohesive, even though the number decreases in favour for the mixture and adhesive fractures after ageing. Clear differences arose with regard to DC. The experimental material reached considerably lower values (31.9–33.2 %) unlike Ceram X Duo (45.6–48.3 %) and Admira (52.9–58.8 %).

Conclusions

The IBS and the DC are far more dependent on the parameter filler volume percent and material than on the polymerisation distance.

Clinical significance

A dimethacrylate-diluent-free ormocer matrix offers a better stability opposite ageing but achieves a lower DC and reliability.