Evaluating the suitability of nicotinic acetylcholine receptor antibodies for standard immunodetection procedures

Nicotinic acetylcholine receptors play important roles in numerous cognitive processes as well as in several debilitating central nervous system (CNS) disorders. In order to fully elucidate the diverse roles of nicotinic acetylcholine receptors in CNS function and dysfunction, a detailed knowledge of their cellular and subcellular localizations is essential. To date, methods to precisely localize nicotinic acetylcholine receptors in the CNS have predominantly relied on the use of anti-receptor subunit antibodies. Although data obtained by immunohistology and immunoblotting are generally in accordance with ligand binding studies, some discrepancies remain, in particular with electrophysiological findings. In this context, nicotinic acetylcholine receptor subunit-deficient mice should be ideal tools for testing the specificity of subunit-directed antibodies. Here, we used standard protocols for immunohistochemistry and western blotting to examine the antibodies raised against the alpha3-, alpha4-, alpha7-, beta2-, and beta4-nicotinic acetylcholine receptor subunits on brain tissues of the respective knock-out mice. Unexpectedly, for each of the antibodies tested, immunoreactivity was the same in wild-type and knock-out mice. These data imply that, under commonly used conditions, these antibodies are not suited for immunolocalization. Thus, particular caution should be exerted with regards to the experimental approach used to visualize nicotinic acetylcholine receptors in the brain.

Clinical efficacy of grafting materials in alveolar ridge augmentation: A systematic review

PURPOSE

To evaluate the efficacy of grafting materials in lateral and vertical ridge augmentations.

MATERIALS AND METHODS

A systematic review of the literature on the clinical use of grafting materials of the years 1995 to April 2015 was conducted using electronic search of PubMed and Cochrane libraries and hand search of eight print journals. A total of 184 papers were included, comprising 6182 patients. Parameters evaluated were observation period [months], bone formation [histologic area%], defect fill [%], horizontal and vertical gain [mm], loss of augmented volume [mm], complication rate [%], and implant survival rate [%]. Results are expressed as weighted means ± SD.

RESULTS

Results were obtained after a weighted mean observation period of 27.4 months (range 3-168 months). Bone formation in the augmented areas varied from 33.2 ± 14.9% for allogeneic grafts to 56.0 ± 25.6% for mixtures of autogenous and other grafting materials. Defect fill in dehiscence defects ranged from 51.0 ± 13.6% (synthetic) to 85.8 ± 13.4% (xenogeneic) for the different materials, with an overall weighted mean of 79.8 ± 18.7%. Weighted mean horizontal gain for all particulate grafting materials was 3.7 ± 1.2 mm, with variation between 2.2 ± 1.2 mm (synthetic) and 4.5 ± 1.0 mm (mixtures of autogenous bone with allogeneic/xenogeneic grafting material) without statistical significance. Weighted overall mean vertical gain was 3.7 ± 1.4 mm. Vertical gain was substantially higher when space-making barrier materials such as titanium meshes were used; however this was also associated with strong increase in complication rate. Block grafts achieved higher horizontal gain by approximately 1 mm. The use of block grafts achieved significantly increased vertical gain compared to particulate material only when autogenous block grafts from extraoral donor sites were used.

CONCLUSION

Horizontal and vertical gain by 3.7 mm on average can be achieved using particulate materials. This can be increased by using titanium meshes. Substantial vertical gains beyond this dimension require the use of extraoral bone block grafts.

Expression of nicotinic acetylcholine receptors in Alzheimer's disease: postmortem investigations and experimental approaches

Nicotinic ligand binding studies have shown rather early that the cholinoceptive system is affected in Alzheimer's disease (AD). Today, molecular histochemistry enables one to study the nicotinic acetylcholine receptor (nAChR) subunit expression on the cellular level in human autopsy brains, in animal models and in in vitro approaches, thus deciphering the distribution of nAChRs and their role as potential therapeutic targets. The studies on the nAChR expression in the frontal and temporal cortex of AD patients and age-matched controls could demonstrate that both, the numbers of alpha4- and alpha7-immunoreactive neurons and the quantitative amount, in particular of the alpha4 protein, were markedly decreased in AD. Because the number of the corresponding mRNA expressing neurons was unchanged these findings point to a translational/posttranslational rather than a transcriptional event as an underlying cause. This assumption is supported by direct mutation screening of the CHRNA4 gene which showed no functionally important mutations. To get more insight into the underlying mechanisms, two model systems organotypic culture and primary hippocampal culture - have been established, both allowing to mimic nAChR expression in vitro. In ongoing studies the possible impact of beta-amyloid (Abeta) on nAChR expression is tested. Preliminary results obtained from primary cultures point to an impaired nAChR expression following Abeta exposure.

Clinical and imaging features of pulmonary strongyloidiasis

We evaluated 20 patients with pulmonary strongyloidiasis for risk factors, clinical and imaging manifestations, complications, treatment, and outcome. Eighteen (90%) had risk factors for strongyloidiasis including steroid use, age greater than 65, chronic lung disease, use of histamine blockers, or chronic debilitating illness. Pulmonary signs and symptoms, including cough, shortness of breath, wheezing, and hemoptysis, were present in 19 (95%); adult respiratory distress syndrome (ARDS) developed in 9 (45%). Pulmonary infiltrates occurred in 18 (90%). Gastrointestinal signs and symptoms were also common. Peripheral blood eosinophilia occurred in 15 (75%). Twelve (60%) had secondary infection, and 3 (15%) had bacterial lung abscesses. All were treated with thiabendazole, 25 mg/kg twice daily; on average, patients without ARDS were treated for 3 days, versus 7 days for those with ARDS. Seventy percent responded to therapy; 30% died. Preexisting chronic lung disease and ARDS were statistically significant predictors of a poor prognosis.

A synthetic model for microsurgical training: a surgical contribution to reduce the number of animal experiments

Microsurgery has grown to be an essential technique in pediatric surgery. Thus, there is an increasing need for basic training and skills maintenance, which require a continuous laboratory training. As an alternative to microsurgical exercises on living animals, a model including a simulation vein, artery and nerve is being introduced. It provides an opportunity to practice microsurgical technique with optimal availability at any time at fairly low cost. Its potentials and limits in the training of microsurgical dissection, anastomosis and quality control are being compared to experiments on anesthetized animals. Although a few exercises on living animals are mandatory to close the gap between the laboratory and the patient, a synthetic model is a valuable tool in microsurgical training and helps to reduce animal experiments.

Parvalbumin-containing interneurons of the human cerebral cortex express nicotinic acetylcholine receptor proteins

Cholinergic fibers from the basal forebrain are known to contact cholinoceptive cortical pyramidal neurons. Recent electrophysiological studies have revealed that nicotinic acetylcholine receptors are also present in human cerebrocortical interneurons. A direct visualization of nicotinic receptor subunits in cortical interneurons has, however, not yet been performed. We have applied double-immunofluorescence using antibodies against parvalbumin --a marker for the Chandelier and basket cell subpopulation of interneurons--and to the alpha4 and alpha7 subunit proteins of the nicotinic acetylcholine receptor. The vast majority of the parvalbuminergic interneurons was immunoreactive for the alpha4 and the alpha7 nicotinic acetylcholine receptor. Provided these receptors would be functional--as suggested by recent electrophysiological findings--the connectivity pattern of cholinergic afferents appears much more complex than thought before. Not only direct cholinergic impact on cortical projection neurons but also the indirect modulation of these by cholinergic corticopetal fibers contacting intrinsic cortical cells would be possible.

Classical Alzheimer features and cholinergic dysfunction: towards a unifying hypothesis?

OBJECTIVE

Our autopsy studies show possible links between classical Alzheimer pathology and decreased expression of nicotinic acetylcholine receptors. For further elucidation we are now using in vitro models. We report preliminary evidence for the impact of beta-amyloid on nicotinic receptor expression in hippocampal dissociation culture.

METHODS

Cultures (E18 rats) were grown in a serum-free medium and incubated at 8 days in vitro for 3 days with 1 microM Abeta1-42. Expression of alpha4, alpha7, and beta2 nicotinic receptor subunit protein was assessed immunohistochemically and rated semiquantitatively.

RESULTS

Abeta1-42 incubation resulted in a massive reduction of alpha4 protein-expressing neurons, this effect was less pronounced for the alpha7 and beta2 subunit protein.

CONCLUSION

These findings provide first evidence for a direct impact of classical Alzheimer pathology features on nicotinic receptor expression in vitro. Our model will be useful for testing the potential of drugs to stop or reverse these effects.

Continuous delivery of rhBMP2 and rhVEGF165 at a certain ratio enhances bone formation in mandibular defects over the delivery of rhBMP2 alone--An experimental study in rats

The aim of the present study was to test the hypothesis that different amounts of vascular endothelial growth factor and bone morphogenic protein differentially affect bone formation when applied for repair of non-healing defects in the rat mandible. Porous composite PDLLA/CaCO3 carriers were fabricated as slow release carriers and loaded with rhBMP2 and rhVEGF165 in 10 different dosage combinations using gas foaming with supercritical carbon dioxide. They were implanted in non-healing defects of the mandibles of 132 adult Wistar rats with additional lateral augmentation. Bone formation was assessed both radiographically (bone volume) and by histomorphometry (bone density). The use of carriers with a ratio of delivery of VEGF/BMP between 0.7 and 1.2 was significantly related to the occurrence of significant increases in radiographic bone volume and/or histologic bone density compared to the use of carriers with a ratio of delivery of ≤ 0.5 when all intervals and all outcome parameters were considered. Moreover, simultaneous delivery at this ratio helped to "save" rhBMP2 as both bone volume and bone density after 13 weeks were reached/surpassed using half the dosage required for rhBMP2 alone. It is concluded, that the combined delivery of rhVEGF165 and rhBMP2 for repair of critical size mandibular defects can significantly enhance volume and density of bone formation over delivery of rhBMP2 alone. It appears from the present results that continuous simultaneous delivery of rhVEGF165 and rhBMP2 at a ratio of approximately 1 is favourable for the enhancement of bone formation.

Point-of-care testing on admission to the intensive care unit: lactate and glucose independently predict mortality

BACKGROUND

The aim of the study was to retrospectively investigate whether parameters of routine point-of-care testing (POCT) predict hospital mortality in critically ill surgical patients on admission to the intensive care unit (ICU).

METHODS

Arterial blood analyses of 1551 patients on admission to the adult surgical ICU of the Technical University Munich were reviewed. POCT was performed on a blood gas analyser. The association between acid-base status and mortality was evaluated. Metabolic acidosis was defined by base excess (BE) <-2 mmol/L and, wherever applicable, subdivided into lactic acidosis by lactate >50% of BE, anion gap (AG)-acidosis by AG >16 mmol/L, hyperchloraemic acidosis by chloride >115 mmol/L. Metabolic alkalosis was defined by BE ≥3 mmol/L. Logistic regression analysis identified variables independently associated with mortality.

RESULTS

Overall mortality was 8.8%. Mortality was greater in male patients (p=0.012). Mean age was greater in non-survivors (p<0.0005). Nine hundred and eighty-six patients showed no metabolic acid-base disorder (mortality 7.3%), thereof 26 patients with pCO(2)>55 mm Hg (mortality 23.1%). Three hundred and seventy-seven patients presented with acidosis (mortality 11.4%), thereof 163 patients with lactic acidosis (mortality 19%). Mortality for alkalosis (174 patients) was 12.1%. Mean blood glucose level for non-survivors was higher compared to survivors (p<0.0005). Logistic regression analysis identified lactate, glucose, age, male gender as independent predictors of mortality.

CONCLUSIONS

Lactate and glucose on ICU admission independently predict mortality. BE and AG failed as prognostic markers. Lactic acidosis showed a high mortality rate implying that lactate levels should be obtained on ICU admission. Prevalence of hyperchloraemic acidosis was low. Metabolic alkalosis was associated with an increased mortality. Further studies on this disturbance and its attendant high mortality are warranted.

Time to progression is dependent on the expression of the tumour suppressor PTEN in ovarian cancer patients

BACKGROUND

Quantitative analyses of PTEN expression of ovarian cancer tissues were performed in this study. PTEN expression was investigated in terms of each patient's progression-free interval to indicate the role of PTEN in the generation of platinum refractory tumours.

MATERIALS AND METHODS

The study group comprised 20 ovarian cancer patients from whom fresh frozen tissues of both the primary tumour and specimens of progressive disease were available. The PTEN protein and phosphorylation of the downstream effector protein kinase B (PKB) were quantified by Western blot analyses and subsequent densitometry. Data were analyzed for individual PTEN variation with respect to the clinical course as defined by the progression-free interval.

RESULTS

Applying the usual clinical criteria for platinum-sensitivity after progression, seven patients were considered platinum-sensitive whereas 13 patients had suffered a progression within 12 months after the chemotherapy. In 5/7 (71%) cases with prolonged time to progression, an increase in PTEN was observed. Decline of PTEN expression occurred in 9/13 (69%) patients with poor outcome. PTEN expression corresponds inversely to PKB phosphorylation in 14/20 (70%) tissues investigated.

CONCLUSIONS

The data suggest that decreased PTEN expression accompanies the progression of ovarian cancer. Declining PTEN expression results in a shortened relapse-free interval, whereas an increase of PTEN prolongs the time to progression. However, as far as recurrence occurs, PTEN is not the only mechanism to suppress tumour progression in ovarian cancer.

Reduced somatosensory impairment by piezosurgery during orthognathic surgery of the mandible

PURPOSE

This clinical trial aimed to test the hypothesis that piezosurgery causes reduced nerval irritations and, thus, reduced somatosensory impairment when used in orthognathic surgery of the mandible.

METHODS

To this end, 37 consecutive patients with Angle Class II and III malocclusion were treated using bilateral sagittal split osteotomies (BSSO) of the mandible. In a split mouth design, randomized one side of the mandible was operated using a conventional saw, while a piezosurgery device was used on the contralateral side. In order to test the individual qualities of somatosensory function, quantitative sensory testings (QSTs) were performed 1 month, 6 months and 1 year after surgery.

RESULTS

A comparison of the data using a two-way analysis of variance (ANOVA) revealed a significant reduction in postoperative impairment in warm detection threshold (WDT) (P = 0.046), a decreased dynamic mechanical allodynia (ALL) (P = 0.002) and a decreased vibration detection threshold (VDT) (P = 0.030) on the piezosurgery side of the mandible as opposed to the conventionally operated control side. In the remaining QSTs, minor deviations from the preoperative baseline conditions and a more rapid regression could be observed.

CONCLUSIONS

Piezosurgery caused reduced somatosensory impairment and a faster recovery of somatosensory functions in the present investigation.

Expression of the alpha4 isoform of the nicotinic acetylcholine receptor in the fetal human cerebral cortex

Nicotinic acetylcholine receptors are likely to play an important role in neuronal migration during development. Furthermore, the alpha4 receptor subunit gene is related to a hereditary juvenile form of epilepsy. Only little information is available, however, on the expression of cerebrocortical nicotinic acetylcholine receptors during human fetal development. Using non-isotopic in situ hybridization and immunohistochemistry, we have studied the distribution of the alpha4 subunit of the nicotinic acetylcholine receptor mRNA and protein in the human frontal cortex at middle (17-24 weeks of gestation) and late (34-42 weeks of gestation) fetal stages. Both, alpha4 receptor mRNA and alpha4 receptor protein were observed beginning during week 17-18 of gestation. At this time of development, a few weakly labeled mRNA-containing cells were present mainly in the ventricular zone, the subplate and the cortical plate. A similar distribution pattern was found for the receptor protein. Around week 38 of gestation, the distribution in the cerebral cortex of alpha4 subunit-containing cells was similar to that of adult human cortices with the highest densities of labeled neurons found in layers II/III, followed by layers V and VI. Nicotinic acetylcholine receptor-containing neurons appear rather early in human fetal development. Given functional maturity, they may interact during cortical development with acetylcholine released from corticopetal fibers or other yet unknown sources subserving the process of neuronal migration and pathfinding.

A new approach in three dimensions to define pre- and intraoperative condyle-fossa relationships in orthognathic surgery - is there an effect of general anaesthesia on condylar position?

Incorrect registration of the condylar position in orthognathic surgery is supposed to cause postoperative relapse, condylar resorption and temporomandibular disorders. The aim of this prospective study was to evaluate the influence of general anaesthesia on centric relation (CR). Therefore, CR registered preoperatively in the awake patient and CR registered intraoperatively under general anaesthesia were recorded in 30 patients (14 men, 16 women) undergoing orthognathic surgery (skeletal class I: n=3, II: n=13, III: n=14; symmetric: n=20; asymmetric: n=10). CR records were digitized and, through superimposition on the preoperative cone beam computed tomography of the patient's skull, the superior, anterior and posterior joint space and the volumetric congruence of 120 condyles were analysed. The linear measurements of joint spaces did not demonstrate any clinically relevant discrepancy between the CR measured in the awake and anaesthetized patient. In contrast, volumetric analysis revealed statistically significant differences between both states, with an intraoperative condylar sag predominantly in the posterior-inferior direction. The patient's skeletal class or symmetry had no significant influence on the intraoperative condylar displacement. Thus, the risk of fixing the condyle in an unphysiological position supports the idea of using intraoperative condylar positioning devices to achieve predictable and stable outcomes.

Alpha4-1 subunit mRNA of the nicotinic acetylcholine receptor in the rat olfactory bulb: cellular expression in adult, pre- and postnatal stages

In addition to their role in signal transduction, nicotinic acetylcholine receptors have been shown in vi-tro to be involved in neuronal growth cone regulation during development. This idea is supported by recent histochemical findings showing that iso- and archicortical nicotinic alpha4-1 receptor mRNA expression precedes cholinergic fiber ingrowth. To test whether this also holds true for rhinencephalic parts of the telencephalon, we have studied the olfactory bulb by digoxigenin-mediated in situ hybridization, using an alpha4-1 isoform-specific riboprobe and an alkaline-phosphatase-based detection system. Development is characterized by early intense alpha4-1 mRNA expression (embryonic day 14), reaching a peak around postnatal day 2 when all olfactory bulb layers are invested with numerous alpha4-1 transcript-bearing neurons. Subsequently, the density of labeled neurons decreases to reach adult levels (postnatal day 120), where strongly labeled neurons remain in the mitral cell layer, outer external plexiform layer, and glomerular layer. The unifying pattern of iso-, archicortical, and rhinencephalic alpha4-1 mRNA expression is its early onset, i.e. preceding cholinergic innervation. This points to a possible role of nicotinic receptors regarding neuronal migration in all three regions.

Do we need retarded delivery of bone growth factors in facial bone repair? An experimental study in rats

The aim of the present study was to evaluate the effect of different dosages of retarded vs. rapid release of bone morphogenic protein 2 (BMP2) at different recipient sites. Porous composite poly(D,L-lactic acid) (PDLLA)/CaCO3 scaffolds were loaded with three different dosages of rhBMP2 (24 µg, 48 µg and 96 µg) and implanted, together with blank controls, both into non-healing defects of the mandibles and into the gluteal muscles of 24 adult male Wistar rats. After 26 weeks, bone formation and expression of bone specific markers [alkaline phosphatase (AP) and Runx2] were evaluated by histomorphometry and immunohistochemistry. Results showed that the mode of delivery had no quantitative effect on bone formation in mandibular sites. Expression of AP and Runx2 showed significant differences among the three dosage groups. There were significant correlations between the expression of both AP and Runx2 as well as the extent of bone formation, with both retarded and rapid release of rhBMP2. In ectopic sites, retarded release significantly enhanced bone formation in the low and medium dosage groups, compared to rapid release. Expression of AP was significantly higher and Runx2 significantly lower in ectopic sites, compared to mandibular sites. Significant correlations between the expression of bone specific markers and bone formation occurred only in the retarded delivery groups, but not in the rapid release groups. Within the limitations of the experimental model, it was concluded that retarded delivery of BMP2 was effective, preferably in sites with low or non-existing pristine osteogenic activity. Expression of bone specific markers indicated that osteogenic pathways might be different in mandibular vs. ectopic sites.

Transport von Blutgasproben

BACKGROUND

Transport of blood gas samples via a pneumatic tube system and subsequent analysis in the central laboratory can reduce costs and errors compared to on-site testing in the operating theatre or the intensive care unit. In this study, a modern pneumatic tube transport system was tested for its usability for this purpose.

METHODS

A total of 4 consecutive blood gas samples were obtained intraoperatively from 54 different patients and sent to the central laboratory. Of these, 3 samples were transferred using the pneumatic tube system but by different methods and 1 sample was transported personally which served as a reference. The results of sample analysis concerning blood gases, electrolytes and haemoglobin were compared and examined for differences.

RESULTS

No statistically significant differences could be determined between the different modes of transportation.

CONCLUSION

Transport of samples for blood gas analysis via a modern pneumatic tube system is safe when samples are correctly prepared.

Influence of tumour necrosis factor alpha on epithelial-mesenchymal transition of oral cancer cells in co-culture with mesenchymal stromal cells

Tumour progression in head and neck squamous cell carcinoma (HNSCC) is influenced by the surrounding stroma and inflammatory cytokines such as tumour necrosis factor alpha (TNF-α). The aim of this study was to test the hypothesis that TNF-α modulates the interactions of HNSCC cell line PCI-13 and bone marrow mesenchymal stromal cells (BMSCs) and influences markers of epithelial-mesenchymal transition (EMT). Following induction with TNF-α, mono- and co-cultures of BMSCs and the established HNSCC cell line PCI-13 were analyzed; protein expression of E-cadherin and vimentin and qRT-PCR expression of Snail, Twist, MMP14, vimentin, E-cadherin, and β-catenin were examined, and changes in cellular AKT signalling were analyzed. TNF-α induced a significant decrease in E-cadherin (64.5±6.0%, P=0.002) and vimentin (10.4±3.5%, P=0.04) protein expression in co-cultured PCI-13, while qRT-PCR showed a significant increase in β-catenin (BMSCs P<0.0001; PCI-13 P=0.0005) and Snail (BMSCs P=0.009; PCI-13 P=0.01). TNF-α also resulted in a down-regulation of AKT downstream targets S6 (38.7±20.9%, P=0.01), p70S6 (16.7±12%, P=0.05), RSK1 (23.6±28.8%, P=0.02), and mTOR (27.4±17.5%, P=0.004) in BMSC co-cultures. In summary, while reducing the expression of vimentin and AKT-signalling in PCI-13 and BMSC, respectively, TNF-α introduced an inflammatory-driven tumour-stroma transition, marked by an increased expression of markers of EMT.

Predictability of maxillary positioning: a 3D comparison of virtual and conventional orthognathic surgery planning

Background

Virtual surgery planning (VSP) is believed to reduce inaccuracies in maxillary positioning compared to conventional surgery planning (CSP) due to the elimination of face-bow transfer and laboratory steps. However, there is still a lack of comparative studies for the accuracy of splint-based maxillary positioning in CSP versus VSP. Therefore, the objective of this retrospective, observational study was to compare if splints produced by VSP and CSP reach postoperative outcomes within clinically acceptable limits.

Methods

The planned and actual postoperative results of 52 patients (VSP: n = 26; CSP: n = 26) with a mean age of 24.4 ± 6.2 years were investigated by three-dimensional (3D) alignment with planning software. The conventional treatment plan was digitized, so that the evaluation of both methods was performed in the same manner using the same coordinate system. Inaccuracies were measured by sagittal, vertical and transversal deviations of the upper central incisors and the inclination of the maxillary occlusal plane between the planned and achieved maxillary positions.

Results

Both methods demonstrated significant differences between the planned and actual outcome. The highest inaccuracies were observed in vertical impaction and midline correction. No significant differences between CSP and VSP were observed in any dimension. Errors in vertical and sagittal dimension intensified each other.

Conclusions

In conclusion, splint-based surgeries reached similar results regardless of the applied planning method and splint production.