[The importance of guidelines in dentistry and dental education]

Evidence-based treatment recommendations are gaining importance within the framework of both medical and dental quality management systems. The scientific findings, which have been evaluated critically by expert committees with regard to their methodological quality, are summarized in easy-to-understand guidelines. All guidelines are evaluated qualitatively in accordance with a balance between consensus and evidence during the drafting process regarding their stages of scientific development. The publication of guidelines and the coordination of guideline development has been carried out by the Association of the Scientific Medical Societies in Germany (AWMF) since its foundation in the 1960s. Forty-four dental guidelines are currently available, which are mostly rated at the highest level (S3) of scientific development. Therefore, recommendations for various treatment protocols are defined for both dental staff at university sites or practices and the implementation of these guidelines into the daily clinical routine is desirable. Poor acceptance and adverse resource requirements are major limitations of the establishment of guidelines with regard to the expansion of evidence-based dentistry. However, these limitations might be overcome by the introduction of basic scientific training within dental universities and increased funding of young researchers in order to ensure high treatment quality and economy in dentistry in the future. Guidelines can facilitate education by providing scientifically validated procedural templates to dental students and assisting educators in meeting the requirements of practical skills.

Anterior Open Bite Malocclusion: From Clinical Treatment Strategies towards the Dissection of the Genetic Bases of the Disease Using Human and Collaborative Cross Mice Cohorts

Anterior open bite malocclusion is a complex dental condition characterized by a lack of contact or overlap between the upper and lower front teeth. It can lead to difficulties with speech, chewing, and biting. Its etiology is multifactorial, involving a combination of genetic, environmental, and developmental factors. Genetic studies have identified specific genes and signaling pathways involved in jaw growth, tooth eruption, and dental occlusion that may contribute to open bite development. Understanding the genetic and epigenetic factors contributing to skeletal open bite is crucial for developing effective prevention and treatment strategies. A thorough manual search was undertaken along with searches on PubMed, Scopus, Science Direct, and Web of Science for relevant studies published before June 2022. RCTs (clinical trials) and subsequent observational studies comprised the included studies. Orthodontic treatment is the primary approach for managing open bites, often involving braces, clear aligners, or other orthodontic appliances. In addition to orthodontic interventions, adjuvant therapies such as speech therapy and/or physiotherapy may be necessary. In some cases, surgical interventions may be necessary to correct underlying skeletal issues. Advancements in technology, such as 3D printing and computer-assisted design and manufacturing, have improved treatment precision and efficiency. Genetic research using animal models, such as the Collaborative Cross mouse population, offers insights into the genetic components of open bite and potential therapeutic targets. Identifying the underlying genetic factors and understanding their mechanisms can lead to the development of more precise treatments and preventive strategies for open bite. Here, we propose to perform human research using mouse models to generate debatable results. We anticipate that a genome-wide association study (GWAS) search for significant genes and their modifiers, an epigenetics-wide association study (EWAS), RNA-seq analysis, the integration of GWAS and expression-quantitative trait loci (eQTL), and micro-, small-, and long noncoding RNA analysis in tissues associated with open bite in humans and mice will uncover novel genes and genetic factors influencing this phenotype.

Narrating the Genetic Landscape of Human Class I Occlusion: A Perspective-Infused Review

This review examines a prevalent condition with multifaceted etiology encompassing genetic, environmental, and oral behavioral factors. It stands as a significant ailment impacting oral functionality, aesthetics, and quality of life. Longitudinal studies indicate that malocclusion in primary dentition may progress to permanent malocclusion. Recognizing and managing malocclusion in primary dentition is gaining prominence. The World Health Organization ranks malocclusions as the third most widespread oral health issue globally. Angle's classification system is widely used to categorize malocclusions, with Class I occlusion considered the norm. However, its prevalence varies across populations due to genetic and examination disparities. Genetic factors, including variants in genes like MSX1, PAX9, and AXIN2, have been associated with an increased risk of Class I occlusion. This review aims to provide a comprehensive overview of clinical strategies for managing Class I occlusion and consolidate genetic insights from both human and murine populations. Additionally, genomic relationships among craniofacial genes will be assessed in individuals with Class I occlusion, along with a murine model, shedding light on phenotype-genotype associations of clinical relevance. The prevalence of Class I occlusion, its impact, and treatment approaches will be discussed, emphasizing the importance of early intervention. Additionally, the role of RNA alterations in skeletal Class I occlusion will be explored, focusing on variations in expression or structure that influence craniofacial development. Mouse models will be highlighted as crucial tools for investigating mandible size and prognathism and conducting QTL analysis to gain deeper genetic insights. This review amalgamates cellular, molecular, and clinical trait data to unravel correlations between malocclusion and Class I phenotypes.

Prevalence of incidental findings in adult vs. adolescent patients in the course of orthodontic X-ray diagnostics

OBJECTIVE

Due to increasing numbers of adult patients presenting to orthodontic practices, an increase in incidental findings on diagnostic X‑rays, which are the cornerstone of orthodontic diagnostics, is expected. This raises the clinically relevant question of whether an age effect exists regarding prevalence, localisation and severity of incidental findings on orthodontic diagnostic X‑rays.

MATERIALS AND METHODS

The clinical, primarily retrospective study examined pathological incidental findings from 600 orthopantomograms (OPT) and lateral cephalogram (LC) images in two groups of orthodontic patients (group I: 150 children/adolescents, age 11.89 ± 2.47 years; group II: 150 adults, age 27.03 ± 10.42 years). Prevalence, localisation and severity of the findings were recorded based on a classification sheet. The assessment was done by three experienced examiners following a systematic approach along the nine locations: mandible, maxilla, dentition, paranasal sinuses, temporomandibular joint, cranial base, orbit, cervical spine, soft tissues.

RESULTS

In all, 1458 incidental findings were detected, with 66% of the findings having occurred away from the dentition. There was a significant age effect (p < 0.001) with respect to the prevalence of incidental findings (group II-adults 1026 findings-OPT: 566/LC 460 vs. group I-children/adolescents 432 findings-OPT: 221/LC 211). Regarding localisation, incidental findings in adults commonly occurred in the dentition, paranasal sinuses and mandibular regions. Furthermore, analysis of the LC images revealed significantly more incidental findings in the area of the cranial base and cervical spine in adults (p < 0.001, p = 0.003). Categorisation according to the severity of the incidental findings showed that 33% of the incidental findings needed further diagnostic investigation and possibly treatment by other specialities.

CONCLUSION

Diagnostic assessment using orthodontic diagnostic X‑rays results in a high prevalence of incidental findings away from the dentition. Particularly in adults, a large number of incidental findings outside the dental/alveolar region may be expected on orthodontic diagnostic X‑rays. Thus, a structured approach during diagnostic assessment is required to minimise the extent to which incidental findings of clinical relevance are overlooked.

Towards Genetic Dissection of Skeletal Class III Malocclusion: A Review of Genetic Variations Underlying the Phenotype in Humans and Future Directions

INTRODUCTION

Skeletal abnormalities and malocclusions have varied features that impact populations globally, impairing aesthetics and lowering life quality. The prevalence of the Skeletal Class III disease is the lowest among all angle malocclusions, with varied prevalence across nations. Environmental, genetic, and societal factors play a role in its numerous etiologies. In this study, we conducted a thorough search across the published data relating to quantitative trait loci (QTL) and the genes associated with Class III progression in humans, discussed these findings and their limitations, and proposed future directions and strategies for studying this phenotype.

METHODS

An inclusive search of published papers in the PubMed and Google Scholar search engines using the following terms: 1. Human skeletal Class III; 2. Genetics of Human skeletal Class III; 3. QTL mapping and gene associated with human skeletal Class III; 4. enriched skeletal Class-III-malocclusion-associated pathways.

RESULTS

Our search has found 53 genes linked with skeletal Class III malocclusion reported in humans, genes associated with epigenetics and phenomena, and the top 20 enriched pathways associated with skeletal Class III malocclusion.

CONCLUSIONS

The human investigations yielded some contentious conclusions. We conducted a genome-wide association study (GWAS), an epigenetics-wide association study (EWAS), RNA-seq analysis, integrating GWAS and expression quantitative trait loci (eQTL), micro- and small-RNA, and long non-coding RNA analysis in tissues connected to skeletal Class III malocclusion phenotype in tissues connected with the skeletal phenotype. Finally, we invite regional, national, and international orthodontists and surgeons to join this effort by contributing human samples with skeletal Class III malocclusion following the accepted Helsinki ethical protocol to challenge these phenomena jointly.

Cytotoxicity of 3D‐printed, milled, and conventional oral splint resins to L929 cells and human gingival fibroblasts

Objectives

Evidence on the biocompatibility of three‐dimensional (3D)‐printed and milled resins for oral splints is limited. This in vitro study assessed the influence of the manufacturing method on the cytotoxicity of oral splint resins on L929 cells and human gingival fibroblasts (GF1).

Materials and Methods

Standardized specimens of four 3D‐printed, two‐milled, one‐thermoformed, and one‐pressed splint resin were incubated with L929 and GF1 cells for 24 h. Immunofluorescence and WST‐8 assay were performed to evaluate cytotoxic effects. One‐way analysis of variance and Tukey's multiple comparison test were applied with the variables “splint resin” and “manufacturing method” (p < .05).

Results

Immunofluorescence showed attachment of L929 and GF1 cells to the splint resins. Irrespective of the manufacturing method, the WST‐8 assay revealed significant differences between splint resins for the viability of L929 and GF1 cells. L929 cells generally showed lower viability rates than GF1 cells. The evaluation of cell viability by the manufacturing method showed no significant differences between 3D printing, milling, and conventional methods.

Conclusions

The cytotoxic effects of 3D‐printed, milled, and conventional oral splint resins were similar, indicating minor influence of the manufacturing method on biocompatibility. Cytotoxicity of the resins was below a critical threshold in GF1 cells. The chemical composition might be more crucial than the manufacturing method for the biocompatibility of splint resins.

Monomer Release from Dental Resins: The Current Status on Study Setup, Detection and Quantification for In Vitro Testing

Improvements in mechanical properties and a shift of focus towards esthetic dentistry led to the application of dental resins in various areas of dentistry. However, dental resins are not inert in the oral environment and may release monomers and other substances such as Bisphenol-A (BPA) due to incomplete polymerization and intraoral degradation. Current research shows that various monomers present cytotoxic, genotoxic, proinflammatory, and even mutagenic effects. Of these eluting substances, the elution of BPA in the oral environment is of particular interest due to its role as an endocrine disruptor. For this reason, the release of residual monomers and especially BPA from dental resins has been a cause for public concern. The assessment of patient exposure and potential health risks of dental monomers require a reliable experimental and analytical setup. However, the heterogeneous study design applied in current research hinders biocompatibility testing by impeding comparative analysis of different studies and transfer to the clinical situation. Therefore, this review aims to provide information on each step of a robust experimental and analytical in vitro setup that allows the collection of clinically relevant data and future meta-analytical evaluations.

A comparative in vitro study on monomer release from bisphenol A-free and conventional temporary crown and bridge materials

This study aimed to investigate the release of common monomers from two conventional and two bisphenol A (BPA)-free temporary crown and bridge materials. Cylindrical samples of all materials were prepared (N = 90; five samples for each material and cycle of analysis). All samples were immersed in high-performance liquid chromatography (HPLC)-grade water and incubated for 1 h, 12 h, 24 h, and 7 days in an incubation shaker at 37°C and 112 rpm. Extraction was performed in accordance with ISO 10993-12. Eluted monomers were detected and quantified by HPLC coupled with ultraviolet-visible spectroscopy and mass spectrometry (HPLC-UV/Vis-MS). Analysis of BPA was performed by HPLC coupled with ultraviolet-visible spectroscopy (HPLC-UV/Vis) and positive results were verified by HPLC-tandem mass spectrometry (HPLC-MS/MS). Neither bisphenol A-glycidyl methacrylate (Bis-GMA) nor BPA was quantifiable in any of the crown and bridge samples investigated in the present study. However, all samples contained triethylene glycol dimethacrylate (TEGDMA) and/or urethane dimethacrylate (UDMA) after 24 h of incubation. Statistical analysis showed that significantly more UDMA was released from the BPA-free materials than from the conventional materials. All concentrations of UDMA measured were below the effective cytotoxic concentrations previously reported. However, for a few materials, especially BPA-free temporary crown and bridge materials, the levels of UDMA were above previously reported potentially harmful concentrations for local cells. As BPA-free materials were introduced as being more biocompatible than materials containing BPA, substitution of Bis-GMA with UDMA should be further investigated.

Osseointegration of a novel 3D porous Ti-6Al-4V implant material - Histomorphometric analysis in rabbits

Porous structure properties are known to conduct initial and long-term stability of titanium alloy implants. This study aims to assess the histomorphometric effect of a 3-D porosity in Ti-6Al-4V implants (PI) on osseointegration in comparison to solid Ti-6Al-4V implants (SI). The PI was produced in a spaceholder method and sintering and has a pore size of mean 400 µm (50 µm to 500 µm) and mimics human trabecular bone. Pairs of PI and equal sized SI as reference were bilaterally implanted at random in the lateral femoral condyle of 16 Chinchilla-Bastard rabbits. The animals were sacrificed after 4 and 12 weeks for histomorphometric analysis. The histomorphometric evaluation confirmed a successful short-term osseohealing (4 weeks) and mid-term osseoremodeling (12 weeks) for both types of implants. The total newly formed bone area was larger for PI than for SI after 4 and 12 weeks, with the intraporous bone area being accountable for the significant difference (p<0.05). A more detailed observation of bone area distribution revealed a bony accumulation in a radius of +/- 500 µm around the implant surface after remodeling. The bone-to-implant contact (BIC) increased significantly (p<0.05) from 4 to 12 weeks (PI 26.23 % to 42.68 %; SI 28.44 % to 47.47 %) for both types of implants. Due to different surface properties, however, PI had a significant (p<0.05) larger absolute osseous contact (mm) to the implant circumference compared to the SI (4 weeks: 7.46 mm vs 5.72 mm; 12 weeks: 11.57 mm vs 9.52 mm [PI vs. SI]). The regional influences (trabecular vs. cortical) on bone formation and the intraporous distribution were also presented. Conclusively, the porous structure and surface properties of PI enable a successful and regular osseointegration and enhance the bony fixation compared to solid implants under experimental conditions.

[Medical notification of occupational skin diseases by dermatologists]

In accordance with § 202 SGB VII, physicians in Germany have a legal obligation to report to the statutory accident insurance institution any justified suspicion of an occupational disease. With regard to skin diseases, various occupational disease numbers (Berufskrankheitennummer = BK No.) can be considered, depending on the type of disease and the type of exposure, e.g. BK No. 3101, 3102, 3104, BK No. 5102 and others in addition to the most common BK No. 5101 and BK No. 5103. The prerequisite for a well-founded suspicion is that occupational effects exist or existed which can be brought into a causal relationship with the skin disease. Form F6000 "Medical notification of a suspected occupational disease" is used for reporting. In the case of the numerically most significant BK No. 5101, there is the special feature that even if the skin disease is classified as occupationally caused, but not as severe or repeatedly relapsing, according to § 41 (1) of the contract between physicians and the accident insurance institutions, every physician is obliged to immediately present the insured person to a dermatologist so that the so-called dermatologist procedure can be initiated to enable the rapid initiation of prevention. Since 1 January 2021, it has been stipulated that the dermatologist's report must be submitted in every case-i.e. both when there is merely the possibility and when there is a well-founded suspicion of the existence of a BK No. 5101. This ensures that preventive measures can be quickly and effectively implemented.

Sequential osseointegration from osseohealing to osseoremodeling - Histomorphological comparison of novel 3D porous and solid Ti-6Al-4V titanium implants

In the present study, we analyzed the histological characteristics of osseointegration of an open-porous Ti-6Al-4V material that was produced in a space holder method creating a 3-D through-pores trabecular design that mimics the inhomogeneity and size relationships of trabecular bone in macro- as well as microstructure. Pairs of cylindrical implants with a porosity of 49 % and an average pore diameter of 400 µm or equal sized solid, corundum blasted devices as reference were bilaterally implanted press fit in the lateral condyles of 16 rabbits. Histological examination was performed after 4 weeks of short-term osseohealing and 12 weeks of mid-term osseoremodeling and we summarized the criteria for sequential osseointegration. After 4 weeks, osteoid had already been largely replaced by mineralized woven bone in both types of implants but was only represented to a greater extent in the deeper pores of PI. The cortical as well as trabecular region showed regular osseohealing with excessive and spatially undirected formation of immature woven bone. A dense bone mass was found in the cortical area, while in the trabecular region the bone mass was reduced distinctly, presenting large lacuna-like recesses and a demarcating trabecular structure. The pores near the implant surface contained more mineralized woven bone than the deeper pores. After 12 weeks, the osseoremodeling was largely completed with a physiological maturation to lamellar bone. The newly formed bone mass increased for PI and SI compared to the 4-week group and osteoid was only detectable in the deeper pores. The inhomogeneous trabecular design of the pores enables an excellent ingrowth of mineralized lamellar bones after remodeling to a pore depth of 1800 µm, which proves a functional load transfer from the surrounding bone into the implant. According to the concept of osseointegration by Branemark and Albrektsson, the histological evaluation confirms a successful, superior osseointegration of the presented porous properties improving long-term implant stability. The presented study protocol allows an excellent evaluation and comparison of the sequential osseointegration from short-term osseohealing to mid-term osseoremodeling.

Long-term diagnostic value of MRI in detecting recurrent aggressive fibromatosis at two multidisciplinary sarcoma centers

PURPOSE

To assess the diagnostic accuracy of MRI in detecting recurrent aggressive fibromatosis (AF) during long-term follow-up at two multidisciplinary sarcoma centers.

METHODS

Seventy-nine patients from two sarcoma centers were included in this IRB-approved study and were examined postoperatively using 1.5-T MRI. MRI follow-up scans were reviewed for true-positive/-negative and false-positive/-negative results. Available pathological reports and MRI follow-ups were set as reference.

RESULTS

The median age of the patients was 38.1 ± 15.3 years. Of the patients 27.9 % showed recurrent AF lesions. The most common localizations of AF were the axilla/shoulder (n = 15) and the thigh (n = 11). From 498 postoperative MRI follow-ups, 24 true-positive, 16 false-positive, 6 false-negative, and 452 true-negative MRI follow-ups were identified. The overall sensitivity and specificity for detecting recurrent AF was 80 % and 97 %, respectively. There was no significant difference in the diagnostic accuracy at the two sarcoma centers. All false-negative results were found in small lesions. False-positive results mostly mimicked streaky (n = 10) and small ovoid/nodular (n = 5) lesions. The configuration of recurrent AF was significantly most often fascicular (50 %; p = 0.001-0.005).

CONCLUSION

MRI shows a high long-term diagnostic value in detecting AF recurrences. Nevertheless, radiologists should pay close attention when lesions are small, as they may remain undetected. Although the configuration of recurrent AF is most often fascicular, recurrences may also appear in different shapes.

Influence of the Casting Concentration on the Mechanical and Optical Properties of FA/CaCl2-Derived Silk Fibroin Membranes

In this study, we describe the manufacturing and characterization of silk fibroin membranes derived from the silkworm Bombyx mori. To date, the dissolution process used in this study has only been researched to a limited extent, although it entails various potential advantages, such as reduced expenses and the absence of toxic chemicals in comparison to other conventional techniques. Therefore, the aim of this study was to determine the influence of different fibroin concentrations on the process output and resulting membrane properties. Casted membranes were thus characterized with regard to their mechanical, structural and optical assets via tensile testing, SEM, light microscopy and spectrophotometry. Cytotoxicity was evaluated using BrdU, XTT, and LDH assays, followed by live-dead staining. The formic acid (FA) dissolution method was proven to be suitable for the manufacturing of transparent and mechanically stable membranes. The fibroin concentration affects both thickness and transparency of the membranes. The membranes did not exhibit any signs of cytotoxicity. When compared to other current scientific and technical benchmarks, the manufactured membranes displayed promising potential for various biomedical applications. Further research is nevertheless necessary to improve reproducible manufacturing, including a more uniform thickness, less impurity and physiological pH within the membranes.

Biomechanical analysis of temporomandibular joint dynamics based on real-time magnetic resonance imaging

AIM

The traditional hinge axis theory of temporomandibular joint (TMJ) dynamics is increasingly being replaced by the theory of instantaneous centers of rotation (ICR). Typically, ICR determinations are based on theoretical calculations or three-dimensional approximations of finite element models.

MATERIALS AND METHODS

With the advent of real-time magnetic resonance imaging (MRI), natural physiologic movements of the TMJ may be visualized with 15 frames per second. The present study employs real-time MRI to analyze the TMJ biomechanics of healthy volunteers during mandibular movements, with a special emphasis on horizontal condylar inclination (HCI) and ICR pathways. The Wilcoxon rank sum test was used to comparatively analyze ICR pathways of mandibular opening and closure.

RESULTS

Mean HCI was 34.8 degrees (± 11.3 degrees) and mean mandibular rotation was 26.6 degrees (± 7.2 degrees). Within a mandibular motion of 10 to 30 degrees, the resulting x- and y-translation during opening and closure of the mandible differed significantly (10 to 20 degrees, x: P = 0.02 and y: P < 0.01; 20 to 30 degrees, x: P < 0.001 and y: P = 0.01). Rotation of both 0 to 10 degrees and > 30 degrees showed no significant differences in x- and y-translation. Near occlusion movements differed only for y-translation (P < 0.01).

CONCLUSION

Real-time MRI facilitates the direct recording of TMJ structures during physiologic mandibular movements. The present findings support the theory of ICR. Statistics confirmed that opening and closure of the mandible follow different ICR pathways, which might be due to muscular activity discrepancies during different movement directions. ICR pathways were similar within maximum interincisal distance (MID) and near occlusion (NO), which might be explained by limited extensibility of tissue fibers (MID) and tooth contact (NO), respectively.

Intraoral sensor-based monitoring of stabilization splint therapy in patients with myofascial pain

AIM

The present study aimed to evaluate intraoral microsensors for the objective measurement of patient compliance during splint therapy and to comparatively analyze the duration of mandibular and maxillary splint application in patients with myofascial pain.

MATERIALS AND METHODS

Thirty-two patients with sole myofascial pain without limited opening (Research Diagnostic Criteria for Temporomandibular Disorders [RDC/TMD] Ia) were divided into two groups. To ensure patient comparability, all pressure-sensitive sites from the initial palpation were summarized as pain scores. The subjects in group 1 were treated with maxillary stabilization splints, and those in group 2 with mandibular stabilization splints. All splints were equipped with a microsensor without interfering static or dynamic occlusion. Wear pattern was recorded at three intervals of 30 days each. Following the observation period, the data were retrieved and statistically evaluated using multi-factor analysis of variance (ANOVA) and the Bland-Altman analysis.

RESULTS

During the observation period, maxillary splints were applied in 44.4% and mandibular splints in 44.2% of the days. Regarding patient compliance, there was no significant difference between the maxillary and mandibular splints (P = 0.359). Patients with an increased pain score (P < 0.0001) and female patients (P = 0.013) wore their splints significantly more often. The wear time decreased over the observation period, whereas only the initial and terminal interval differed significantly across both the mandibular and maxillary splint groups (P < 0.0001).

CONCLUSION

The microsensor used in the present study was an effective and reliable tool for monitoring patient compliance in patients with temporomandibular disorders (TMD). This method also allows for the reliable recording of intraoral splint application prior to the required bite elevations. The two types of splints analyzed in the present study had no significant influence on compliance.

Configuration of Primary and Recurrent Aggressive Fibromatosis on Contrast-Enhanced MRI with an Evaluation of Potential Risk Factors for Recurrences in MRI Follow-Up

PURPOSE

 To analyze the appearance of primary and recurrent aggressive fibromatosis (AF) on MRI with a focus on configuration and to determine potential risk factors for recurrences detected on MRI follow-up scans.

METHODS

 From 79 consecutive patients with histologically proven diagnosis of AF, 39 patients underwent a minimum of four 1.5 T MRI follow-up scans after resection of primary AF between 2008 and 2018. The primary and recurrent tumors were radiographically examined for configuration, limitation and extent on MRI. Epidemiological data and loco-regional subcutaneous edema, muscle edema and post-operative seroma were included.

RESULTS

 The mean age of the patients was 39 ± 2.6 years. Primary and recurrent AF most often occurred in the thigh. The main appearance of primary AF was significantly most often fascicular (p = 0.001-0.01) with heterogeneous and marked contrast enhancement. 21 % (n = 8) of the patients developed recurrences of AF. A fascicular configuration with homogeneous/heterogeneous contrast enhancement was the main appearance of recurrent AF, but recurrent AF appeared nodular, polycyclic, ovoid or streaky/flat as well. Recurrent AF significantly most often occurred within the first 9 months after primary tumor resection (p = 0.009), especially in patients up to 25 years of age (RR = 6.1; 95 % CI: 1.8-20.9; p = 0.004). The cases of recurrent AF were altogether significantly smaller than the primary tumors (p = 0.001). Post-treatment subcutaneous and muscle edema were present in 77 % and 56 %, respectively. Patients with muscle edema after primary tumor resection had a significantly higher risk for AF recurrences (relative risk ratio (RR) = 1.8; 95 % CI: 1.16-2.8; p = 0.0096). There was no significant difference detected in patients with complete or incomplete resection of the primary tumor.

CONCLUSION

 Primary and recurrent aggressive fibromatosis has a mostly fascicular configuration, but may appear ovoid, nodular, streaky/flat or polycyclic as well. High risks for tumor recurrences are detected for patients up to 25 years of age, patients within the first 9 post-operative months and patients with muscle edema after primary tumor resection.

KEY POINTS

  · Primary aggressive fibromatosis mostly has a fascicular configuration with heterogeneous contrast enhancement. · Recurrent aggressive fibromatosis usually has a fascicular configuration with heterogeneous/homogeneous contrast enhancement. · Patients within the first 9 post-operative months and up to 25 years of age have a significantly higher risk for recurrences. · Muscle edema after resection of primary aggressive fibromatosis is associated with a significantly higher risk for recurrences.

CITATION FORMAT

· Sedaghat S, Surov A, Krohn S et al. Configuration of Primary and Recurrent Aggressive Fibromatosis on Contrast-Enhanced MRI with an Evaluation of Potential Risk Factors for Recurrences in MRI Follow-Up. Fortschr Röntgenstr 2020; 192: 448 - 457.

Multi-slice real-time MRI of temporomandibular joint dynamics

OBJECTIVES

The purpose of this work was to improve the clinical versatility of high-speed real-time MRI studies of temporomandibular joint (TMJ) dynamics by simultaneous recordings of multiple MRI movies in different sections.

METHODS

Real-time MRI at 3 T was realized using highly undersampled radial FLASH acquisitions and image reconstruction by regularized nonlinear inversion (NLINV). Multi-slice real-time MRI of two, three or four slices at 0.75 mm resolution and 6 to 8 mm thickness was accomplished at 50.0 ms, 33.3 ms or 25.5 ms temporal resolution, respectively, yielding simultaneous movies at 2 × 10, 3 × 10 or 4 × 10 frames per second in a frame-interleaved acquisition mode. Real-time MRI movies were evaluated by three blinded raters for visibility of the anterior and posterior border of disc, shape of the disk body and condyle head as well as movement of the disc and condyle (1 = excellent, 5 = no visibility).

RESULTS

Effective delineation of the disk atop the mandibular condyle was achieved by T1-weighted images with opposed-phase water-fat contrast. Compared to 8 mm sections, multi-slice recordings with 6 mm thickness provided sharper delineation of relevant structures as confirmed by inter-rater evaluation. Respective dual-slice and triple-slice recordings of a single TMJ as well as dual-slice recordings of both joints (one slice per TMJ) received the highest visibility ratings of ≤ 2 corresponding to high confidence in diagnostic content.

CONCLUSIONS

The improved access to TMJ dynamics by multi-slice real-time MRI will contribute to more effective treatment of temporomandibular disorders.

Decitabine demonstrates antileukemic activity in B cell precursor acute lymphoblastic leukemia with MLL rearrangements

Background

Promotor hypermethylation of CpG islands is common in B cell precursor acute lymphoblastic leukemia (BCP-ALL) with mixed lineage leukemia (MLL) gene rearrangements. Hypomethylating agents (HMA) such as azacitidine (AZA) and decitabine (DEC) reduce DNA hypermethylation by incorporation into DNA and were successfully introduced into the clinic for the treatment of myeloid neoplasias.

Methods

Here, we investigated whether HMA induce comparable biological effects in MLL-positive BCP-ALL. Further, efficacy of HMA and concomitant application of cytostatic drugs (cytarabine and doxorubicin) were evaluated on established SEM and RS4;11 cell lines. In addition, promising approaches were studied on BCP-ALL cell line- and patient-derived xenograft models.

Results

In general, DEC effects were stronger compared to AZA on MLL-positive BCP-ALL cells. DEC significantly reduced proliferation by induction of cell cycle arrest in G0/G1 phase and apoptosis. Most sensitive to HMA were SEM cells which are characterized by a fast cell doubling time. The combination of low-dose HMA and conventional cytostatic agents revealed a heterogeneous response pattern. The strongest antiproliferative effects were observed when ALL cells were simultaneously exposed to HMA and cytostatic drugs. Most potent synergistic effects of HMA were induced with cytarabine. Finally, the therapeutic potential of DEC was evaluated on BCP-ALL xenograft models. DEC significantly delayed leukemic proliferation in xenograft models as demonstrated longitudinally by non-invasive bioluminescence as well as ¹⁸F-FDG-PET/CT imaging. Unexpectedly, in vivo concomitant application of DEC and cytarabine did not enhance the antiproliferative effect compared to DEC monotherapy.

Conclusions

Our data reveal that DEC is active in MLL-positive BCP-ALL and warrant clinical evaluation.

Electronic supplementary material

The online version of this article (10.1186/s13045-018-0607-3) contains supplementary material, which is available to authorized users.

Primary stability and osseointegration of dental implants in polylactide modified bone - A pilot study in Goettingen minipigs

The present study aimed to evaluate primary stability (PS) and osseointegration of dental implants in polylactide [70/30 poly(l-lactide-co-d, l-lactide); (PLDLA)] modified bone in 30 Goettingen minipigs. Each animal received three implants per jaw quadrant. In a split-mouth design, one side of the maxilla and mandible was randomly allocated to the experimental treatment (PLDLA applied into the drill hole before implantation), while the contralateral sides served as intraindividual controls (no PLDLA applied). The required insertion torque and the implant stability quotient (ISQ) were measured during implantation. ISQ, volume density (VD) of new bone formation (NBF), and the bone-implant contact (BIC) were evaluated at the end of the observation period (1, 3, 6, 12, and 24 months, respectively) in six animals each. Across all study groups, the PLDLA treatment resulted in a) a comparable insertion torque, b) an equivalent ISQ, c) a reduced BIC, and d) a reduced VD of NBF, as opposed to the untreated controls. In conclusion, the PLDLA treatment did not affect the PS, but rather led to an impaired osseointegration, which was particularly strong in the compact mandibular bone, and decreased in the spongious maxillary bone. PLDLA induced anchoring in spongious bone should be evaluated in further investigations.

Influence of synthetic polyethylene glycol hydrogels on new bone formation during mandibular augmentation procedures in Goettingen minipigs

Polyethylene glycol hydrogels (PEG) have been used as slow release carrier for osteoinductive growth factors in order to achieve a retarded delivery. However, there have been concerns about negative effects on bone regeneration. This study aims to test whether PEG hydrogels themselves affect new bone formation (NBF), when used as a carrier during mandibular augmentation procedures. In a randomized split-mouth design, bilateral mandibular bone defects were surgically created in 12 Goettingen minipigs, and subsequently augmented, using PEG hydrogel on one side of the mandible. The contralateral sides, without PEG, served as controls. After 4 and 12 weeks, bone formation was evaluated in six animals each. A comparison of the data, using a three-way analysis of variance (ANOVA), revealed a significant effect of the healing time and the region of the graft on the distribution and enhancement of NBF (P < .0001, respectively). Although a 0.3% (95%-CI [-5.5; 4.8]) lower volume density of newly formed bone could be observed over all PEG hydrogel sections, in contrast to the contralateral controls, the analysis revealed no clinically significant effects of the PEG hydrogel treatment on the total level (P = 0.90), and the distribution of NBF (P = 0.54). In conclusion, PEG hydrogels do not affect NBF when used as a carrier for osteoinductive growth factors during mandibular augmentation procedures.

[Effects of intravenous clonidine on recovery and postanaesthetic analgesic requirements.]

Pain and pain-related sympathoadrenergic reactions (hypertension, tachycardia) accompanied by nausea, vomiting and shivering are the most common side effects of recovery from anaesthesia. The alpha(2)agonist clonidine acts as a sedative, anxiolytic, antihypertensive, antiemetic, antisialogogue and decreases the incidence of shivering. Thus, we studied the effects of intraoperatively administered clonidine on the recovery period and the postoperative analgesic requirements in patients undergoing maxillofacial surgery.

METHODS

After approval by the local Ethics Commitee and after informed consent had been given, 40 patients scheduled for elective maxillofacial surgery were included in this double-blind, randomized study. As a supplement to standardized general anaesthesia (isoflurane, N(2)O), the patients received either clonidine 5 mug/kg or placebo during the last hour of the operation. Blood pressure, heart rate, time of recovery, and sedation and pain scores were measured postoperatively. The occurrence of nausea, vomiting or shivering was noted, as were the requirements of piritramide for analgesia, which was administered on demand in titrating dosages, and of nifedipine for systolic blood pressure exceeding 180 mm Hg.

RESULTS

The two groups were comparable regarding biometric parameters, ASA-classification and duration of anaesthesia. Clonidinetreated patients were later in opening their eyes (22.5+/-11.9 min vs 17.9+/-10.9; n.s.) and the ability to state their dates of birth returned later (32.2+/-11.6 min vs. 25.7+/-12.8;P<0.05). Pain was more frequent in the placebo group (P<0.05 after 30 min), and there-fore, these patients required much more piritramid (P<0.01). The sedation scores showed no significant differences. No vomiting occurred in the clonidine group, and shivering was less frequent (P<0.01). The placebo group received more nifedipine (P<0.05) because the rate-pressure product was higher (P<0.01).

DISCUSSION

Opiates are frequently used as analgesics after maxillofacial surgery, even though their most common side effect-respiratory depression, nausea and vomiting-are particularly dangerous in these patients because of the obstruction of the upper respiratory tract. Self-titration of the opiate dosage on demand can decrease the incidence of serious side effects. Clonidine administered intraoperatively caused a profound reduction in analgesic requirements in this study. Additional opiate administration in the postoperative period was unnecessary in nearly all clonidine-treated patients. The attenuating effect on sympathoadrenergic reactions leads to lowering of the rate-pressure product and may be of advantage for patients suffering from arterial hypertension, angina pectoris or bronchial asthma. The slower emergence from anaesthesia following clonidine administration is probably caused by double-blind study properties preventing full consideration of the decreased isoflurane requirements after clonidine.

A predicted operon map for Mycobacterium tuberculosis

The prediction of operons in Mycobacterium tuberculosis (MTB) is a first step toward understanding the regulatory network of this pathogen. Here we apply a statistical model using logistic regression to predict operons in MTB. As predictors, our model incorporates intergenic distance and the correlation of gene expression calculated for adjacent gene pairs from over 474 microarray experiments with MTB RNA. We validate our findings with known examples from the literature and experimentation. From this model, we rank each potential operon pair by the strength of evidence for cotranscription, choose a classification threshold with a true positive rate of over 90% at a false positive rate of 9.1%, and use it to construct an operon map for the MTB genome.

Improved test of time dilation in special relativity

An improved test of time dilation in special relativity has been performed using laser spectroscopy on fast ions at the heavy-ion storage-ring TSR in Heidelberg. The Doppler-shifted frequencies of a two-level transition in 7Li+ ions at v=0.064c have been measured in the forward and backward direction to an accuracy of Deltanu/nu=1 x 10(-9) using collinear saturation spectroscopy. The result confirms the relativistic Doppler formula and sets a new limit of 2.2 x 10(-7) for deviations from the time dilation factor gamma(SR)=(1-v2/c2)(-1/2).

Rate coefficients and final states for the dissociative recombination of LiH+

The dissociative recombination of LiH+ ions with low-energy electrons is observed at a storage ring and the final states are analyzed using fragment imaging and field ionization techniques. The rate coefficient is found to be larger than its estimated value used in astrophysical models. Mostly the highest energetically possible Rydberg states of the lithium atom are populated by the reaction, indicating a common trend for molecular recombination via the noncrossing mode.

Two- and three-body kinematical correlation in the dissociative recombination of H(3)(+)

Fragmentation patterns for dissociative recombination of the triatomic hydrogen molecular ion H(3)(+) in the vibrational ground state have been measured using the storage ring technique and molecular fragment imaging. A broad distribution of vibrational states in the H(2) fragment after two-body dissociation and a large predominance of nearly linear momentum geometries after three-body dissociation are found. The fragmentation results are directly contrasted with Coulomb explosion imaging data on the initial H(3)(+) geometry, compared to existing wave-packet calculations, and considered in the light of a simple physical picture.

Influence of magnetic fields on electron-Ion recombination at very low energies

Radiative recombination (inverse photoionization) is believed to be well understood since the beginning of quantum mechanics. Still, modern experiments consistently reveal excess recombination rates at very low electron-ion center-of-mass energies. In a detailed study on recombination of F6+ and C6+ ions with magnetically guided electrons we explored the yet unexplained rate enhancement, its dependence on the magnetic field B, the electron density n(e), and the beam temperatures T( perpendicular) and T( ||). The excess scales as T(-1/2)( perpendicular) and, surprisingly, as T(-1/2)( ||), increases strongly with B, and is insensitive to n(e). This puts strong constraints on explanations of the enhancement.

[Degradation of halothane, enflurane, and isoflurane by dry soda lime to give carbon monoxide]

In the presence of completely dry soda lime volatile anaesthetics will decompose to carbon monoxide (CO). In an in vitro study, the absorbent (soda lime, ICI) was dried with a constant gas flow of 11/min oxygen for 120 h. The weight loss during the drying was 17.1%. Two vol% of halothane, enflurane or isoflurane in oxygen was administered with a constant flow of 0.51/min oxygen through the completely dry absorbent. Concentrations of gases were measured before and after the absorbent using mass spectrometry (MGA 1100, Perkin-Elmer) and an electrochemical NO monitor (Mini PAC CO, Dräger). The temperature inside the soda lime was monitored continuously. Shortly after adding the anaesthetic to the oxygen passing through the absorbent, carbon monoxide appeared in the outlet of the soda lime container. The measured peak concentrations varied around 450 ppm (halothane), 3500 ppm (enflurane) and 3800 ppm (isoflurane). The temperature inside the absorbent rose from the ambient temperature (19.8 degrees C) to a maximum of 52.1 degrees C during CO production and decreased when the CO production lowered after approximately 1 h (all anaesthetics). During CO production no measurable concentration of halothane left the absorber. After passing through the absorbent the concentrations of isoflurane and enflurane were slightly lower than the corresponding concentrations in the fresh gas measured before absorption.

Evaluation of two electrochemical monitors for measurement of inhaled nitric oxide

Inhaled in low concentrations, nitric oxide (NO) acts as a potent pulmonary vasodilator, but when inhaled in high concentrations NO and its metabolite NO2 are potentially toxic molecules. Thus, an accurate and reproducible measurement of both NO and NO2 is necessary, and changes in NO concentration need to be detected instantly to avoid lung damage (high concentrations) or failure of NO therapy (low concentrations; unnoticed interruption of NO supply). We investigated two electrochemical NO monitors (Sensor Stik 4586 and Dräger PAC II) for accuracy and time constants. Both provided accurate and reproducible results at different NO concentrations. Known NO concentrations (standards: 10, 50, 75 ppm) were detected within a 3% tolerance, and acceptable time constants were seen when NO concentration was abruptly increased from zero to 50 ppm. The display read the final value within 60 s with the Sensor Stik and 11 s with the Dräger PAC II. Significant differences were seen when the NO concentration was rapidly reduced from 50 ppm to zero. The Sensor Stik took more than 2 h to reach zero, whereas the PAC II took 60 s.

[Patient-controlled analgesia with clonidine and piritramide]

Following parenteral administration, clonidine has analgesic effects at both cerebral and spinal levels. Patient-controlled analgesia (PCA) makes it possible to determine equipotent dosages of analgesics by relating analgesic consumption per time to the levels of analgesia obtained in comparable patient populations. Therefore, we studied the equipotency ratios of clonidine and piritramide and the incidence of undesired side effects in the treatment of postoperative pain in patients undergoing maxillo-facial surgery.

METHODS

After approval of the local ethics committee and informed consent 40 patients (age > 18 year, ASA I-III) were studied. Following randomization, the patients each received a PCA device containing either clonidine (bolus 30 micrograms), or piritramide (bolus 1.5 mg) for treatment of postoperative pain (lockout interval 5 min in both groups). During the postoperative period, pain was determined using a visual analogue scale, while analgesic consumption, sedation, haemodynamic parameters, respiration rate, and the occurrence of undesired side effects were documented additionally.

RESULTS

The groups had comparable distributions of biometric data, duration of anaesthesia, and ASA classification. Pain level decreased significantly (P < 0.0001) in both groups during the first 2 h of PCA. Mean arterial pressure and heart rate were lower (P < 0.05) in the clonidine group 4 and 6 h after PCA onset, while the degree of sedation after 2 (P < 0.01) and 6 (P < 0.05) h was higher than in the piritramide group. Nausea and vomiting were more frequent (P < 0.05) in the piritramide group. Both groups showed a wide interpatient variation in analgesic requirement. The equipotency ratio clonidine/piritramid was 1:63.7.

CONCLUSION

Intravenous clonidine is a potent analgesic and is suitable or the treatment of postoperative pain following maxillo-facial surgery. The analgesic potency of 150 micrograms clonidine i.v. was equivalent to that of 9.56 mg piritramide i.v. Nausea and vomiting occurred more rarely in the clonidine group, while deeper sedation was observed more frequently than in the piritramide group. Owing to the wide interindividual variation of analgesic consumption, clonidine dosages have to be adjusted to the actual requirements.

[Intraoperative thrombosis of the inferior vena cava]

A pre-term infant weighing 900 g, gestational age 25 weeks, developed an acute abdomen. Intravenous lines had been inserted previously in the left (silastic catheter) and right (24 G cannula) saphenous veins in the neonatal intensive care unit. During surgical exploration, a perforation of the terminal ileum was found. The operation consisted in partial resection of the perforated ileum with an end-to-end anastomosis and a double-lumen colostomy. Major blood loss during the procedure caused serious haemodynamic problems. Despite transfusion of erythrocyte (100 ml), thrombocytes (75 ml), and albumin (50 ml), the patient developed bradycardia and hypotension. Administration of atropine, adrenaline, and calcium i.v. had no effect. The operation could be finished only with extrathoracic resuscitation. When the drapes were removed, livid, swollen lower limbs raised the suspicion of an acute thrombosis of the inferior vena cava. After insertion of a 24 G i.v. cannula into a vein of the right upper arm, the circulation stabilised after rapid transfusion of 40 ml blood and 25 ml thrombocytes and resuscitation was successful. Paediatricians and anaesthesiologists must consider the risk of thrombosis of the vena cava. If venous lines in the lower limbs are not visible to the anaesthesiologist during the operation, venipuncture of veins of an upper limb is recommended before starting the surgical procedure. Due to the high incidence of vena cava thrombosis caused by central venous lines and the difficulty of peripheral venipuncture in pre-termintanty, a safe venous line should be inserted if necessary by pre-operative venesection.

[Nitric oxide in therapy of pulmonary hypertension after correction of congenital single atrium]

We report on a 19-month-old boy with congenital single atrium. Cardiac catheterization preceding the surgical repair revealed an elevated pulmonary artery pressure of 60/15 mmHg (mean pressure 40 mmHg). Pulmonary flow was 8.4 l/min.m2 and systemic flow was 5.5 l/min.m2. Pulmonary arteriolar resistance was elevated to 4.2 U.m2 with 64% left-right shunt and 25% right-left shunt. Arterial O2-saturation varied around 90%. After surgical repair (insertion of a Goretex patch), the patient required mechanical ventilation with 100% oxygen for adequate oxygenation. Cardiac catheterization was repeated on the first postoperative day. No residual shunts were found. The pulmonary artery pressure was 66/40 mmHg (mean pressure 50 mmHg), systemic arterial pressure was 85/62 mmHg (mean pressure 68 mmHg). Cardiac index was 2.8 l/min.m2, pulmonary vascular resistance was 12 U.m2. After administration of prostacyclin a significant decrease of pulmonary artery pressure was observed, but without changing the ratio between pulmonary and systemic pressure. The AaDO2 varied between 400 and 580 mmHg and the oxygenation-index (PaO2/FiO2) was less than 1.0. In this situation, an attempt with inhaled nitric oxide (NO) was performed. After adding 20 ppm NO to the inspired gas, the AaDO2 decreased significantly from 580 to 270 mmHg and the oxygenation-index (OI) rose from 0.9 to 1.5. The inspired fraction of oxygen could be reduced quickly to 60%. During the next days, the concentration of NO was reduced stepwise to 1 ppm. Finally, the AaDO2 was within the normal range (25-65 mmHg) and the OI rose to a level about 4.0. The FiO2 could be reduced to 30% and nitric oxide therapy could be stopped and the child could be extubated.

[Malignant hyperthermia in swine during isoflurane anesthesia]

A case of porcine malignant hyperthermia (MH) is reported, which occurred during a cardiological animal experiment under general anaesthesia using isoflurane as inhalational anaesthetic. Initially, tachycardia (238 bpm) and a sudden increase of end-exspiratory pCO2 were noticed. Discontinuation of isoflurane followed by administration of dantrolene (7 mg/kg body weight) led to a rapid recovery. Two days later, no difference in clinical state was apparent in comparison with the remaining swine. After regular euthanasia, acute muscle necrosis was seen macroscopically in back and glutaeal muscles, which was confirmed by histological examination. The rise of end-tidal pCO2 was the striking symptom thus allowing the detection of the incipient malignant hyperthermia. Early onset of dantrolene therapy is shown to be sufficient in termination of this hyperacute complication, and may prevent its deleterious outcome. Therefore, the administration of dantrolene should be taken into account in case of porcine MH, especially in time-consuming and costly series of animal experiments.

[Postoperative monitoring of microvascular flap repair with pulse oximetry--initial experience]

The surgical success of microvascular free flaps or pedicled flaps depends on the function of the nutritive vessels. Complications such as thrombosis or vessel kinking, are dangerous and may result in flap loss. During the last decade, different methods were tested for their capability of monitoring flap perfusion. We report our preliminary experience with the continuous and non-invasive pulse oximetry by using a special reflection sensor positioned on the surface of the flap.

Chemistry of fruit flies: Glandular secretion ofBactrocera (Polistomimetes) visenda (Hardy)

The major component (>90% of volatiles) of the male rectal glandular extract of the nonpest speciesBactrocera visenda (Hardy) is 3-methyl2-butenyl acetate, with minor components being the isomeric 3-methyl-3-butenyl acetate, the homologous esters, 3-methyl-2-butenyl propanoate and 3-methyl-2-butenyl formate, along with 3-methyl-2-buten-1-ol, 3-methyl-2-butenal, and 3-methylbutyl acetate. None of these compounds has been identified previously from aBactrocera species, supporting the view thatBactrocera visenda is taxonomically distant from otherBactrocera species identified from the Australian mainland. This collection of compounds adds to the known types utilized by dipteran species and emphasizes their extensive biosynthetic capability.

[Suitability of capacitive sensors for measuring relative humidity in anesthetic gas systems]

A capacitive sensor was tested for its suitability for measuring relative humidity in an anaesthetic gas circuit. The valvo sensor PH1 was tested using various different anaesthetic gas mixtures. Measuring accuracy was influenced neither by such volatile anaesthetics as isoflurane and halothane, nor by oxygen or nitrous oxide. The response time of the sensor depends on its position within the gas, and in the most favourable case is about 3 minutes. The sensor is readily incorporated within an existing gas circuit. The linearity of the characteristic curve must be corrected by external electronic compensation to avoid measuring problems in the lower humidity range.

Metabolism of Dibenzofuran by Pseudomonas sp. Strain HH69 and the Mixed Culture HH27

A Pseudomonas sp. strain, HH69, and a mixed culture, designated HH27, were isolated by selective enrichment from soil samples. The pure strain and the mixed culture grew aerobically on dibenzofuran as the sole source of carbon and energy. Degradation proceeded via salicylic acid which was branched into the gentisic acid and the catechol pathway. Both salicylic acid and gentisic acid accumulated in the culture medium of strain HH69. The acids were slowly metabolized after growth ceased. The enzymes responsible for their metabolism showed relatively low activities. Besides the above-mentioned acids, 2-hydroxyacetophenone, benzopyran-4-one (chromone), several 2-substituted chroman-4-ones, and traces of the four isomeric monohydroxydiben-zofurans were identified in the culture medium. 2,2′,3-Trihydroxybiphenyl was isolated from the medium of a dibenzofuran-converting mutant derived from parent strain HH69, which can no longer grow on dibenzofuran. This gives evidence for a novel type of dioxygenases responsible for the attack on the biarylether structure of the dibenzofuran molecule. A meta -fission mechanism for cleavage of the dihydroxylated aromatic nucleus of 2,2′,3-trihydroxybiphenyl is suggested as the next enzymatic step in the degradative pathway.

Volatile Secretions in Three Species of Dufourea (Hymenoptera: Halictidae) Bees: Chemical Composition and Phylogeny

Volatile secretions from Dufour’s glands in three species of Dufourea bees, Dufourea (Halictoides) dentriventris (Nylander). D.(H.) inermis (Nylander) and D. (Dufourea) minuta Lepelletier have been studied by gas chromatography and mass spectrometry. It was found that the secretions are composed of complex blends of straight chain saturated and unsaturated 2- and 3-ketones and scries of hexanoic and octanoic esters. Cephalic secretions from males and females of D.(H.) inermis and D.(D.) minuta contain sex- and species-specific blends of methylcarbinols and corresponding long chain carboxylic esters. Mass spectrometric fragmentation patterns of esters are described.