[Safety of patient care on an interprofessional training ward in visceral surgery]. / Sicherheit der Patientenversorgung auf einer viszeralchirurgischen interprofessionellen Ausbildungsstation.

BACKGROUND: Interprofessional training wards (ITW) are increasingly being integrated into teaching and training concepts in visceral surgery clinics. OBJECTIVE: How safe is patient care on an ITW in visceral surgery? MATERIAL AND METHODS: Data collection took place from November 2021 to December 2022. In this nonrandomized prospective evaluation study the frequency and severity of adverse events (AE) in 3 groups of 100 patients each in a tertiary referral center hospital for visceral surgery were investigated. The groups consisted of patients on the ITW and on the conventional ward before and after implementation of the ITW. The Global Trigger Tool (GTT) was used to search for AE. Simultaneously, a survey of the treatment was conducted according to the Picker method to measure patient reported outcome. RESULTS: Baseline characteristics and clinical outcome parameters of the patients in the three groups were comparable. The GTT analysis found 74 nonpreventable and 5 preventable AE in 63 (21%) of the patients and 12 AE occurred before the hospital stay. During the hospital stay 50 AE occurred in the operating theater and 17 on the conventional ward. None of the five preventable AE (in 1.7% of the patients) was caused by the treatment on the ITW. Patients rated the safety on the ITW better than in 90% of the hospitals included in the Picker benchmark cohort and as good as on the normal ward. CONCLUSION: The GTT-based data as well as from the patients' point of view show that patient care on a carefully implemented ITW in visceral surgery is safe.

Retrospective evaluation of the orthodontic treatment needs in primary school children with Robin sequence following Tübingen palatal plate therapy in infancy.

INTRODUCTION: The aim of this study was to investigate the orthodontic treatment needs (OTN) of children with RS treated with the TPP in infancy compared to age- and sex-matched controls. METHODS: The aim of this study was to investigate the orthodontic treatment needs (OTN) of children with RS treated with the TPP in infancy compared to age- and sex-matched controls. RESULTS: In 21 children with RS (n = 23; 19 non-syndromic, 4 syndromic; average age 9.9 years) showed high OTN, which was significantly higher than in controls (n = 21). The latter of 9 controls had minor OTN, followed by 8 participants with borderline OTN. Regarding the intraoral picture, patients with RS had an increased open bite tendency. Without considering the presence of a cleft palate, 16 children with RS had high or very high OTN, compared to 4 of controls. CONCLUSIONS: Patients with RS have significantly higher OTN than healthy controls, independent of cleft occurrence. RS is associated with dental anomalies and special skeletal growth patterns, both increasing malocclusion and negatively affecting dentoalveolar growth. This should raise awareness for identifying these needs and provide a comprehensive orthodontic treatment, where functional rehabilitation should be favored over aesthetic results.

Oral health-related quality of life in patients with cleft lip and/or palate or Robin sequence.

PURPOSE: To compare the oral health-related quality of life (OHRQoL) in patients with cleft lip and/or palate or Robin sequence versus a healthy control group using the Child Oral Health Impact Profile (COHIP-G19). Factors such as age, gender, and cleft type were considered. METHODS: Over an 8-month period, the OHRQoL was surveyed by using the COHIP-G19 questionnaire. Included were patients with a craniofacial disorder (n = 61; average age 11.24 years) and a healthy control group (n = 70, average age 12.63 years) for a total of 131 patients (average age 11.99 years) from the Department of Orthodontics University Hospital Tübingen, Germany. These were divided into two age groups (6-11 years; 12-18 years). RESULTS: Statistically, patients with a craniofacial disorder presented a significantly lower OHRQoL than the control group (p = 0.0055). In the craniofacial disorder group, older patients revealed a significantly (p = 0.005) lower OHRQoL than the younger patients. Female patients showed in nearly all groups a better OHRQoL than male patients, but this difference was not statistically significant (p > 0.05). Males with a craniofacial disorder scored significantly lower than males without (p = 0.016); females showed no differences between the groups. Visibility, location, and severity of the craniofacial malformation did not have a significant influence on the OHRQoL. CONCLUSION: The occurrence of a craniofacial malformation impacted the OHRQoL especially in older and male affected patients, unrelated to the expression level or localization. An early instruction about oral health, rehabilitation and functional training should be considered in therapy.

Tooth agenesis in German orthodontic patients with non-syndromic craniofacial disorder: a retrospective evaluation of panoramic radiographs.

OBJECTIVES: The study objective was to evaluate the tooth agenesis in German orthodontic patients with non-syndromic cleft lip and/or palate and Robin sequence compared to a control group without craniofacial disorder. MATERIALS/METHODS: A total of 108 panoramic radiographs were examined using the binary system of Tooth Agenesis Code (TAC) (excluding the third molar). Patients were divided into the craniofacial disorder group 1 (n = 43) and the healthy control group 2 (n = 65). Parameters such as skeletal class malformation, sex, localization of the cleft, craniofacial disorder, and interobserver reliability were assessed. RESULTS: Permanent tooth agenesis was observed in 44% of group 1 and 14% in group 2 with a statistically significant higher prevalence (p = 0.00162 (χ2)). Fourteen different TAC patterns were observed in group 1, ten of these occurring only once in separate patients. The distribution of the TAC codes in group 2 showed nine different possibilities of TAC code patterns; seven TACs were unique. In group 1, the most frequently absent teeth were the maxillary lateral incisor of the left side (30%); in group 2, the second premolar of the lower jaw on the right side (9%). Male patients with craniofacial disorder showed a higher percentage of tooth agenesis than female. CONCLUSION: The data presented here shows a statistically significant higher prevalence of tooth agenesis in German patients with non-syndromic craniofacial disorder. CLINICAL RELEVANCE: Radiographic evaluation enables the diagnosis of tooth agenesis. Recognizing early on the higher prevalence of tooth agenesis in patients exhibiting a craniofacial disorder is an important issue when developing long-term and comprehensive interdisciplinary treatment.

Technical note on introducing a digital workflow for newborns with craniofacial anomalies based on intraoral scans - part II: 3D printed Tübingen palatal plate prototype for newborns with Robin sequence.

BACKGROUND: Orthodontic treatment of newborns and infants with Robin-Sequence using the Tübingen Palatal Plate (TPP) is a complex procedure that could benefit from simplification through digitalization. The design of the velar extension (spur) and the palatal base determines the success of the treatment. Therefore, a prototype must be produced and inserted under endoscopic supervision in order to determine the appropriate shape, length and position of the spur. This technical note demonstrates a fully digital workflow for the design and manufacturing of a functional TPP prototype, based on an intraoral scan. This prototype can be altered and individualized digitally for each patient. After the shape and position of the spur have been optimized, the prototype is duplicated using a silicone mold. Then the definitive TPP is manufactured and inserted. We aim to present a workflow which facilitates the fitting procedure and does not require a conventional impression or a physical model to create the appliance. METHODS: As described in part I of this series, the intraoral scan is performed using the 3Shape TRIOS3 scanner and its corresponding acquisition software. The virtual model is rendered in the 3Shape ortho appliance designer and the base of the palatal plate is designed in the 3Shape dental designer. The palatal plate and the virtual model are then imported into Autodesk Meshmixer and a standardized spur is positioned and merged with the base. The TPP is exported in Standard Tessellation Language (STL) format and manufactured on a W2P Solflex 170 DLP printer using VOCO VPrint Splint material (MDR Class IIa). RESULTS: Based on an intraoral scan, the TPP prototype could be successfully manufactured and proved suitable for the patients' treatment. CONCLUSION: The new digital workflow for the design of the TPP can been successfully implemented into daily clinical routine in our facility. Patients could be alleviated from having to undergo conventional impression procedures and fitting of the TPP could be facilitated by producing multiple functional prototypes for endoscopic evaluation. Through rapid prototyping, the expenditure of the fitting process was reduced, which makes the TPP therapy more efficient and accessible to a wider range of clinicians.

Severe odontogenic infections with septic progress - a constant and increasing challenge: a retrospective analysis.

BACKGROUND: More than 90% of all infections in the head and neck region can be traced back to an odontogenic origin. In rare cases they can lead to sepsis, which may pose a vital threat to the patient. The purpose of this study was to analyse characteristics concerning etiology and progress of severe odontogenic infections with a fulminant development. METHODS: All patients with odontogenic infections requiring hospital admission were included in a retrospective analysis conducted from 02/2012 to 09/2017. Of 483 patients 16 patients (13 male, 3 female) showed severe exacerbation with septic progress. The average age was 52.8 years. All patients underwent at least one surgical procedure that involved an extraoral incision and drainage as well as high volume irrigation intraoperatively. At least one revision was required for four of the patients. Three patients showed an exceedingly severe disease progression with multiorgan dysfunction syndrome (MODS) and circulatory arrest. Antibiotic treatment was adjusted according to the results of an antibiogram and resistogram. Irrigation with saline was done several times a day. RESULTS: Sixteen patients showed odontogenic infections that spread over multiple maxillo-facial and cervical regions accompanied by septic laboratory signs. All these patients needed intensive care and a tracheostomy. The hospitalization period was 27.8 days on average. In 16 cases risk factors for the development of odontogenic abscesses like diabetes mellitus, obesity, chronic alcohol and nicotine abuse, rheumatism and poor oral hygiene were present. Intraoperative swabs showed a typical polymicrobial aerobic and anaerobic spectrum of oral bacteria, especially anaerobes and streptococci, mainly Streptocococcus viridans. CONCLUSION: Odontogenic infections with fulminant progression should be treated based on clinical and imaging data with immediate surgical incision and drainage including elimination of odontogenic foci as well as intensified intra- and postoperative irrigation. If needed, repeat imaging followed by further incisions should be performed. Immediate antibiotic treatment adapted to the antibiogram is of utmost importance. A combination of tazobactam and piperacillin has proven to be a good first choice and can be recommended for abscesses that spread over multiple levels with initial signs of severe infections.

Changing the perception of premenstrual dysphoric disorder - An online-experiment using the Stereotype Content Model.

Women with Premenstrual Dysphoric Disorder (PMDD) are often faced with prejudices about the premenstrual phase. The aim of this study was to investigate whether providing information (psychoeducation) could improve study participants' perception of a PMDD-patient and whether experimentally-induced prejudices about PMDD resulted in stigmatization. Two hundred sixteen students (50% female; aged 18-42 years) from Philipps University Marburg participated in January 2014. Participants were randomly assigned to one of two experimental groups (EG1, EG2) or to a control group (CG). EG1 read a text informing about PMDD. EG2 read a text with stereotypic PMDD-information. CG received a text with information unrelated to PMDD. Then, all participants watched a video of a woman reporting about her PMDD. Finally, participants appraised the woman on the cognitive dimensions warmth and competence as well as on PMDD-related attributes (depressive symptoms, emotional regulation). Participants of EG1 rated the woman as warmer (p <  .001), more competent (p =  .006), and with less depressive symptoms (p < .001) than the CG. The results by study group did not differ by gender. Stereotypic information did not differ significantly among the study groups. Psychoeducation can facilitate the understanding of PMDD-patients and should be integrated in future research on PMDD-treatments.

Termite soldiers contribute to social immunity by synthesizing potent oral secretions.

The importance of soldiers to termite society defence has long been recognized, but the contribution of soldiers to other societal functions, such as colony immunity, is less well understood. We explore this issue by examining the role of soldiers in protecting nestmates against pathogen infection. Even though they are unable to engage in grooming behaviour, we find that the presence of soldiers of the Darwin termite, Mastotermes darwiniensis, significantly improves the survival of nestmates following entomopathogenic infection. We also show that the copious exocrine oral secretions produced by Darwin termite soldiers contain a high concentration of proteins involved in digestion, chemical biosynthesis, and immunity. The oral secretions produced by soldiers are sufficient to protect nestmates against infection, and they have potent inhibitory activity against a broad spectrum of microbes. Our findings support the view that soldiers may play an important role in colony immunity, and broaden our understanding of the possible function of soldiers during the origin of soldier-first societies.

The obese brain as a heritable phenotype: a combined morphometry and twin study.

BACKGROUND: Body weight and adiposity are heritable traits. To date, it remains unknown whether obesity-associated brain structural alterations are under a similar level of genetic control. METHODS: For this study, we utilized magnetic resonance imaging data from the Human Connectome Project. Voxel-based morphometry was used to investigate associations between body mass index (BMI) and regional gray matter volume (GMV) in a sample of 875 young adults with a wide BMI range (386 males/489 females; age 28.8±3.7 years; BMI 26.6±5.3 kg m-2) that included 86 pairs of monozygotic twins and 82 pairs of dizygotic twins. Twin data were analyzed by applying the additive genetic, common environmental and residual effects model to determine heritability of brain regions that were associated with BMI. RESULTS: We observed positive associations between BMI and GMV in the ventromedial prefrontal cortex and the right cerebellum and widespread negative associations within the prefrontal cortex, cerebellum, temporal lobes and distinct subcortical structures. Varying degrees of heritability were found for BMI-associated brain regions, with the highest heritability estimates for cerebellar GMV and subcortical structures. CONCLUSIONS: These data indicate that brain regions associated with obesity are subject to differing levels of genetic control and environmental influences. Specific brain regions with high heritability might represent an inherent vulnerability factor for obesity.

Deactivation of the left dorsolateral prefrontal cortex in Prader-Willi syndrome after meal consumption.

BACKGROUND/OBJECTIVES: Prader-Willi syndrome (PWS) is a type of human genetic obesity that may give us information regarding the physiology of non-syndromic obesity. The objective of this study was to investigate the functional correlates of hunger and satiety in individuals with PWS in comparison with healthy controls with obesity, hypothesizing that we would see significant differences in activation in the left dorsolateral prefrontal cortex (DLPFC) based on prior findings. SUBJECTS/METHODS: This study compared the central effects of food consumption in nine individuals with PWS (7 men, 2 women; body fat 35.3±10.0%) and seven controls (7 men; body fat 28.8±7.6%), matched for percentage body fat. H2(15)O-PET (positron emission tomography) scans were performed before and after consumption of a standardized liquid meal to obtain quantitative measures of regional cerebral blood flow (rCBF), a marker of neuronal activity. RESULTS: Compared with obese controls, PWS showed altered (P<0.05 family-wise error cluster-level corrected; voxelwise P<0.001) rCBF before and after meal consumption in multiple brain regions. There was a significant differential rCBF response within the left DLPFC after meal ingestion with decreases in DLPFC rCBF in PWS; in controls, DLPFC rCBF tended to remain unchanged. In more liberal analyses (P<0.05 family-wise error cluster-level corrected; voxelwise P<0.005), rCBF of the right orbitofrontal cortex (OFC) increased in PWS and decreased in controls. In PWS, ΔrCBF of the right OFC was associated with changes in appetite ratings. CONCLUSIONS: The pathophysiology of eating behavior in PWS is characterized by a paradoxical meal-induced deactivation of the left DLPFC and activation in the right OFC, brain regions implicated in the central regulation of eating behavior.

Site-specific analysis of von Willebrand factor O-glycosylation.

BACKGROUND: O-glycosylation of von Willebrand factor (VWF) affects many of its functions; however, there is currently no information on the occupancy of the 10 putative O-glycosylation sites. OBJECTIVES: The aim of this study was the site-specific analysis of VWF O-glycosylation. METHODS: Tryptic VWF-O-glycopeptides were isolated by lectin affinity chromatography and/or by reverse-phase high-performance liquid chromatography. Subsequently, the purified glycopeptides were analyzed by glycosidase digestion and mass spectrometry. RESULTS: We found that all 10 predicted O-glycosylation sites in VWF are occupied. The majority of the glycan structures on all glycosylation sites is represented by disialyl core 1 O-glycan. The presence of core 2 O-glycan was also confirmed; interestingly, this structure was not evenly distributed among all 10 glycosylation sites. Analysis of the glycopeptides flanking the A1 domain revealed that generally more core-2-type O-glycan was present on the C-terminal Cluster 2 glycopeptide (encompassing T(1468) , T(1477) , S(1486) and T(1487) ) compared with the N-terminal Cluster 1 glycopeptide (encompassing T(1248) , T(1255) , T(1256) and S(1263) ). Disialosyl motifs were present on both glycopeptides flanking the A1 domain and on the glycosylation site T(2298) in the C1 domain. In addition, we identify sulfation of core 2 O-glycans and the presence of the rare Tn antigen. CONCLUSIONS: This is the first study to describe the qualitative and semi-quantitative distribution of O-glycan structures on all 10 O-glycosylation sites, which will provide a valuable starting point for further studies exploring the functional and structural implications of O-glycosylation in VWF.

Impact of high dietary zinc on zinc accumulation, enzyme activity and proteomic profiles in the pancreas of piglets.

The exocrine pancreas plays an important role in zinc homeostasis. Feeding very high (2000-3000mgzinc/kg diet) levels of zinc oxide to piglets for short periods is a common practice in the swine industry to improve performance and prevent diseases. The impact on pancreatic function and possible side effects during long-term feeding of high dietary zinc levels are still poorly understood. A total of 54 weaned piglets were either fed with low (57mg/kg, LZn), normal (164mg/kg, NZn) or high (2425mg/kg, HZn) zinc concentration in the diets. After 4 weeks of feeding, ten piglets per treatment were euthanized and pancreas samples were taken. Tissue zinc concentration and metallothionein abundance was greater with HZn compared with NZn and LZn (P<0.05). Similarly, activity of α-amylase, lipase, trypsin and chymotrypsin was higher with HZn as compared with NZn and LZn diets (P<0.05), whereas elastase activity was unchanged. Total trolox equivalent antioxidative capacity of pancreas tissue was higher with HZn diets compared with the other treatments (P<0.05). Pancreatic protein profiles of NZn and HZn fed piglets were obtained by 2D-DIGE technique and revealed 15 differentially expressed proteins out of 2100 detected spots (P<0.05). The differentially expressed proteins aldose reductase, eukaryotic elongation factor II and peroxiredoxin III were confirmed by immunoblotting. Identified proteins include zinc finger-containing transcription factors and proteins mainly associated with oxidative stress response and signal transduction in HZn compared with NZn pigs. Histologic examination however showed no morphologic changes. The results suggest that long-term supply of very high dietary zinc increases zinc and metallothionein concentration, and digestive enzyme activity, but also triggers oxidative stress reactions in the pancreas of young pigs. The data provide new insights into pancreatic function under outbalanced zinc homeostasis.

Identification of immunodominant proteins of the microalgae Prototheca by proteomic analysis.

Prototheca zopfii associated with bovine mastitis and human protothecosis exists as two genotypes, of which genotype 1 is considered as non-infectious and genotype 2 as infectious. The mechanism of infection has not yet been described. The present study was aimed to identify genotype 2-specific immunodominant proteins. Prototheca proteins were separated using two-dimensional gel electrophoresis. Subsequent western blotting with rabbit hyperimmune serum revealed 28 protein spots. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry analysis resulted in the identification of 15 proteins including malate dehydrogenase, elongation factor 1-alpha, heat shock protein 70, and 14-3-3 protein, which were previously described as immunogenic proteins of other eukaryotic pathogens.

Body composition and energy expenditure predict ad-libitum food and macronutrient intake in humans.

BACKGROUND: Obesity is the result of chronic positive energy balance. The mechanisms underlying the regulation of energy homeostasis and food intake are not understood. Despite large increases in fat mass (FM), recent evidence indicates that fat-free mass (FFM) rather than FM is positively associated with intake in humans. METHODS: In 184 humans (73 females/111 males; age 34.5±8.8 years; percentage body fat: 31.6±8.1%), we investigated the relationship of FFM index (FFMI, kg m(-2)), FM index (FMI, kg m(-2)); and 24-h energy expenditure (EE, n=127) with ad-libitum food intake using a 3-day vending machine paradigm. Mean daily calories (CAL) and macronutrient intake (PRO, CHO, FAT) were determined and used to calculate the relative caloric contribution of each (%PRO, %CHO, %FAT) and percent of caloric intake over weight maintaining energy needs (%WMENs). RESULTS: FFMI was positively associated with CAL (P<0.0001), PRO (P=0.0001), CHO (P=0.0075) and FAT (P<0.0001). This remained significant after adjusting for FMI. Total EE predicted CAL and macronutrient intake (all P<0.0001). FMI was positively associated with CAL (P=0.019), PRO (P=0.025) and FAT (P=0.0008). In models with both FFMI and FMI, FMI was negatively associated with CAL (P=0.019) and PRO (P=0.033). Both FFMI and FMI were negatively associated with %CHO and positively associated with %FAT (all P<0.001). EE and FFMI (adjusted for FMI) were positively (EE P=0.0085; FFMI P=0.0018) and FMI negatively (P=0.0018; adjusted for FFMI) associated with %WMEN. CONCLUSION: Food and macronutrient intake are predicted by FFMI and to a lesser degree by FMI. FFM and FM may have opposing effects on energy homeostasis.

Tandem duplication of KIT exon 11 influences the proteome of canine mast cell tumours.

Mutations with permanent activation of the stem cell factor receptor KIT have been identified as one potential cause for canine cutaneous mast cell tumours (MCTs). The exact changes in global gene expression patterns associated with permanent activation of KIT in these tumours are unknown. The present study compares, by the use of two dimensional difference gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, the proteomes of canine MCTs, with and without KIT exon 11 tandem duplication. Fifteen differentially expressed proteins were identified in mutated MCTs. These are mainly involved in cytoskeleton structure and cell motility (ACTR2, ACTB and CAPPA1), cell signalling (ARHGDIA) and lipid metabolism (ALOX15 and ACSBG4), or are serum proteins. The results therefore support the notion that KIT mutation is associated with changes in the proteome of affected cells with a major effect on the composition of the cytoskeletal proteome and cell motility proteins. No overlaps were identified when the results were compared with a recent study on the proteomic differences between low- and high-grade tumours, suggesting that KIT-mutated tumours may be regarded as a separate entity of high-grade tumours with potential relevance to therapeutic strategies.

Endothelial barrier antigen-immunoreactivity is conversely associated with blood-brain barrier dysfunction after embolic stroke in rats.

While the concept of the Neurovascular Unit (NVU) is increasingly recognized for exploring mechanisms of tissue damage in ischemic stroke, immunohistochemical analyses are of interest to specifically visualize constituents like the endothelium. Changes in immunoreactivity have also been discussed to reflect functional aspects, e.g., the integrity of the blood-brain barrier (BBB). This study aimed to characterize the endothelial barrier antigen (EBA) as addressed by the antibody SMI-71 in a rat model of embolic stroke, considering FITC-albumin as BBB leakage marker and serum levels of BBB-associated matrix metalloproteinases (MMPs) to explore its functional significance. Five and 25 h after ischemia onset, regions with decreased BBB integrity exhibited a reduction in number and area of EBA-immunopositive vessels, while the stained area per vessel was not affected. Surprisingly, EBA content of remaining vessels tended to be increased in areas of BBB dysfunction. Analyses addressing this interrelation resulted in a significant and inverse correlation between the vessels' EBA content and degree of BBB permeability. In conclusion, these data provide evidence for a functional relationship between EBA-immunoreactivity and BBB dysfunction in experimental ischemic stroke. Further studies are required to explore the underlying mechanisms of altered EBA-immunoreactivity, which might help to identify novel neuroprotective strategies.

Differences in the proteome of high-grade versus low-grade canine cutaneous mast cell tumours.

Cutaneous mast cell tumours (MCTs) are the most common skin tumours in dogs. However, the molecular differences between benign tumours with a good prognosis and highly malignant, invasive and metastatic tumours with short survival times are for the most part unclear. In the present study the proteome of low-grade MCTs with a good prognosis was compared with that of poor-prognosis high-grade tumours independent of their mutational status of exon 11 of the KIT gene. Using two-dimensional difference gel electrophoresis and mass spectrometry, 13 proteins with a significant differential expression between the two groups were identified. Four stress response proteins (HSPA9, PDIA3, TCP1A and TCP1E) were significantly up-regulated in high-grade tumours, while proteins mainly associated with cell motility and metastasis had either increased (WDR1, ACTR3, ANXA6) or decreased (ANXA2, ACTB) expression levels. High-grade tumours also had a paradox down-regulation of transferrin, a protein that is usually up-regulated in neoplastic cells. The histologically observable dedifferentiation of high-grade tumours was reflected by decreased tryptase protein expression levels. Results of quantitative real-time RT-PCR analysis indicated that the differences in protein expression levels of most proteins were regulated at the transcript level. Based on these findings, it is hypothesized that high-grade MCT cells have a higher resistance to cellular stress and thus are able to better cope with the adverse environment in highly proliferating tumours independent of increased KIT signalling. It is noteworthy that some of the proteins identified have been proposed as therapeutic targets for human oncology and it will be interesting to evaluate their therapeutic and diagnostic potential for canine MCTs.

Modification of the secondary structure of angiotensin II by substitution of hydrogen with Cs cations: an experimental and theoretical study.

MALDI mass spectrometry in combination with post-source decay (PSD) analysis is a fast and easy to apply method for peptide sequencing. In this study, the PSD technique was used to investigate the influence of the adaption of one, two, and three caesium cations to angiotensin II in the gas phase. The PSD spectra of caesium-aggregated angiotensin II show far less fragmentation in comparison to the protonated one. In the case of singly (doubly) Cs(+) substituted angiotensin II, the PSD mass spectrum shows only fragments with one (two) Cs cation(s). These results are interpreted in terms of additional interactions of the caesium cation(s) with the peptide. In order to investigate this suggestion, the molecular structures were calculated with semi-empirical molecular dynamic (MD) simulations and further optimized at the quantum chemical level (BP86, SVP) of theory. On the one hand, secondary structures of Cs(+) substituted angiotensin II are more compact than the structure of protonated angiotensin II, indicating electrostatic interactions of the Cs cations and the heterocyclic structures. Moreover, oxyphilic interactions of the cations with the oxygen atoms of the peptide backbone also contribute as further van-der-Waals interactions of the Cs(+) substituted angiotensin II. These interactions are able to explain its higher stability due to reduced dissociation in comparison to the protonated angiotensin II. On the other hand, most MD simulations of doubly and triply Cs(+) substituted angiotensin II show a formation of a [2 Cs] cluster, surrounded by the peptide molecule. The formation of this cluster would explain the lack of singly Cs(+) substituted fragments in the PSD mass spectrum of doubly Cs(+) substituted angiotensin II.

Lipophorin of lower density is formed during immune responses in the lepidopteran insect Galleria mellonella.

Injection of heat-killed bacteria into larvae of the greater wax moth Galleria mellonella is followed by changes in lipoprotein composition in the hemolymph. Density gradient centrifugation experiments revealed that within the first four hours after injection, a part of larval lipoprotein, high-density lipophorin (HDLp), was converted into a lipoprotein of lower density. SDS-polyacrylamide gel electrophoresis analysis of the gradient fractions and sequencing of protein fragments, established that the exchangeable apolipoprotein apolipophorin III (apoLp-III), a potent immune-activator, was associated with this newly formed lipophorin. To investigate further the influence of lipophorin-associated apoLp-III on immune-related reactions, we performed in vitro studies with isolated hemocytes from G. mellonella and lipophorins from the sphinx moth Manduca sexta, as a natural source of high amounts of low-density lipophorin (LDLp) and HDLp. The hemocytes were activated to form superoxide radicals upon incubation with LDLp, but not with HDLp. Fluorescence-labeled LDLp was specifically taken up by granular cells. This process was inhibited by adding an excess of unlabeled LDLp, but not by HDLp. We hypothesize that larval lipophorin formed in vivo is an endogenous signal for immune activation, specifically mediated by the binding of lipid-associated apoLp-III to hemocyte membrane receptors.