Carbonic anhydrase generates a pH gradient in Bombyx mori silk glands

Silk is a protein of interest to both biological and industrial sciences. The silkworm, Bombyx mori, forms this protein into strong threads starting from soluble silk proteins using a number of biochemical and physical cues to allow the transition from liquid to fibrous silk. A pH gradient has been measured along the gland, but the methodology employed was not able to precisely determine the pH at specific regions of interest in the silk gland. Furthermore, the physiological mechanisms responsible for the generation of this pH gradient are unknown. In this study, concentric ion selective microelectrodes were used to determine the luminal pH of B. mori silk glands. A gradient from pH 8.2 to 7.2 was measured in the posterior silk gland, with a pH 7 throughout the middle silk gland, and a gradient from pH 6.8 to 6.2 in the beginning of the anterior silk gland where silk processing into fibers occurs. The small diameter of the most anterior region of the anterior silk gland prevented microelectrode access in this region. Using a histochemical method, the presence of active carbonic anhydrase was identified in the funnel and anterior silk gland of fifth instar larvae. The observed pH gradient collapsed upon addition of the carbonic anhydrase inhibitor methazolamide, confirming an essential role for this enzyme in pH regulation in the B. mori silk gland. Plastic embedding of whole silk glands allowed clear visualization of the morphology, including the identification of four distinct epithelial cell types in the gland and allowed correlations between silk gland morphology and silk stages of assembly related to the pH gradient. B. mori silk glands have four different epithelial cell types, one of which produces carbonic anhydrase. Carbonic anhydrase is necessary for the mechanism that generates an intraluminal pH gradient, which likely regulates the assembly of silk proteins and then the formation of fibers from soluble silk proteins. These new insights into native silk formation may lead to a more efficient production of artificial or regenerated silkworm silk fibers.

TGF-β1-induced EMT promotes targeted migration of breast cancer cells through the lymphatic system by the activation of CCR7/CCL21-mediated chemotaxis

Tumor cells frequently disseminate through the lymphatic system during metastatic spread of breast cancer and many other types of cancer. Yet it is not clear how tumor cells make their way into the lymphatic system and how they choose between lymphatic and blood vessels for migration. Here we report that mammary tumor cells undergoing epithelial–mesenchymal transition (EMT) in response to transforming growth factor-β (TGF-β1) become activated for targeted migration through the lymphatic system, similar to dendritic cells (DCs) during inflammation. EMT cells preferentially migrated toward lymphatic vessels compared with blood vessels, both in vivo and in 3D cultures. A mechanism of this targeted migration was traced to the capacity of TGF-β1 to promote CCR7/CCL21-mediated crosstalk between tumor cells and lymphatic endothelial cells. On one hand, TGF-β1 promoted CCR7 expression in EMT cells through p38 MAP kinase-mediated activation of the JunB transcription factor. Blockade of CCR7, or treatment with a p38 MAP kinase inhibitor, reduced lymphatic dissemination of EMT cells in syngeneic mice. On the other hand, TGF-β1 promoted CCL21 expression in lymphatic endothelial cells. CCL21 acted in a paracrine fashion to mediate chemotactic migration of EMT cells toward lymphatic endothelial cells. The results identify TGF-β1-induced EMT as a mechanism, which activates tumor cells for targeted, DC-like migration through the lymphatic system. Furthermore, it suggests that p38 MAP kinase inhibition may be a useful strategy to inhibit EMT and lymphogenic spread of tumor cells.

BRI2 ectodomain affects Aβ42 fibrillation and tau truncation in human neuroblastoma cells

Alzheimer's disease (AD) is pathologically characterized by the presence of misfolded proteins such as amyloid beta (Aβ) in senile plaques, and hyperphosphorylated tau and truncated tau in neurofibrillary tangles (NFT). The BRI2 protein inhibits Aβ aggregation via its BRICHOS domain and regulates critical proteins involved in initiating the amyloid cascade, which has been hypothesized to be central in AD pathogenesis. We recently detected the deposition of BRI2 ectodomain associated with Aβ plaques and concomitant changes in its processing enzymes in early stages of AD. Here, we aimed to investigate the effects of recombinant BRI2 ectodomain (rBRI276-266) on Aβ aggregation and on important molecular pathways involved in early stages of AD, including the unfolded protein response (UPR), phosphorylation and truncation of tau, as well as apoptosis. We found that rBRI276-266 delays Aβ fibril formation, although less efficiently than the BRI2 BRICHOS domain (BRI2 residues 113-231). In human neuroblastoma SH-SY5Y cells, rBRI276-266 slightly decreased cell viability and increased up to two-fold the Bax/Bcl-2 ratio and the subsequent activity of caspases 3 and 9, indicating activation of apoptosis. rBRI276-266 upregulated the chaperone BiP but did not modify the mRNA expression of other UPR markers (CHOP and Xbp-1). Strikingly, rBRI276-266 induced the activation of GSK3β but not the phosphorylation of tau. However, exposure to rBRI276-266 significantly induced the truncation of tau, indicating that BRI2 ectodomain can contribute to NFT formation. Since BRI2 can also regulate the metabolism of Aβ, the current data suggests that BRI2 ectodomain is a potential nexus between Aβ, tau pathology and neurodegeneration.

Agreement between ambulance nurses and physicians in assessing stroke patients

OBJECTIVES

If an ambulance nurse could bypass the emergency department (ED) and bring suspected stroke patients directly to a CT scanner, time to thrombolysis could be shortened. This study evaluates the level of agreement between ambulance nurses and emergency physicians in assessing the need for a CT scan, and interventions and monitoring beforehand, in patients with suspected stroke and/or a lowered level of consciousness.

METHODS

From October 2008 to June 2009, we compared the ambulance nurses' and ED physicians' judgement of 200 patients with stroke symptoms. Both groups answered identical questions on patients' need for a CT scan, and interventions and monitoring beforehand.

RESULTS

There was poor agreement between ambulance nurses and ED physicians in judging the need for a CT scan: κ = 0.22 (95% confidence interval (CI), 0.06-0.37). The nurses' ability to select the same patients as the physician for a CT scan had a sensitivity of 84% (95% CI, 77-89) and a specificity of 37% (95% CI, 23-53). Agreement concerning the need for interventions and monitoring was also low: κ = 0.32 (95% CI, 0.18-0.47). In 18% of cases, the nurses considered interventions before a CT scan unnecessary when the physicians' deemed them necessary.

CONCLUSIONS

Additional tools to support ambulance nurses decisions appear to be required before suspected stroke patients can be taken directly to a CT scanner.

C-peptide: a molecule balancing insulin states in secretion and diabetes-associated depository conditions

Gradually, the C-peptide part of proinsulin has evolved from being viewed upon as a side product of insulin synthesis and secretion to being considered as a bioactive peptide with endocrine functions. Independent of these, its biophysical properties and peptide interactions point to still further roles of C-peptide, in particular regarding possible links to diabetes-related protein aggregations. Insulin, which can deposit at the injection sites in the treatment of diabetes, and islet amyloid polypeptide (IAPP), which can form amyloid fibrils in the islets of Langerhans in diabetes type 2, are kept nonaggregated by charge-based interactions with C-peptide at defined stoichiometries. It is possible that the conformational stabilization of insulin and IAPP by C-peptide may also counterbalance their aggregational tendencies at the high peptide concentrations in the pancreatic β-cell secretory granules. The concentration imbalances of C-peptide, insulin, and IAPP from the hyperpeptidism early in T2DM patients and the insulin-only injections in T1DM patients may distort equilibria of these peptide interactions and promote protein aggregation. Additionally, the chaperone-like actions of C-peptide may increase bioavailability of insulin supplements given to T1DM patients and prevent the formation of insulin deposits. Similarly, peptide interactions may influence depository tendencies in additional peptide systems. In short, biophysical studies are relevant to establish all roles of peptide imbalances in T1DM and T2DM and associated depository diseases.

Five-year follow-up of 11C-PIB uptake in Alzheimer's disease and MCI

PURPOSE

The aim of this study was to evaluate the longitudinal changes in [(11)C]PIB uptake in mild cognitive impairment (MCI) and Alzheimer's disease (AD) over a long-term follow-up.

METHODS

Six AD patients, ten MCI patients and eight healthy subjects underwent a [(11)C]PIB PET scan at baseline and at 2 and 5 years. The clinical status of the MCI patients was evaluated every 6 months.

RESULTS

The MCI group showed a significant increase in [(11)C]PIB uptake over time (p < 0.001), with a similar increase from baseline to 2 years (4.7% per year) and from 2 to 5 years (5.0% per year). Eight MCI patients (80%) converted to AD, and two of these patients showed a normal [(11)C]PIB scan at baseline but increased uptake later. There was an increase in [(11)C]PIB uptake with time in the AD group (p = 0.02), but this did not significantly differ from the change in the control group.

CONCLUSION

Our results revealed a significant increase in amyloid load even at the time of AD diagnosis in some of the MCI patients who converted. A positive [(11)C]PIB scan at baseline in MCI patients strongly predicted future conversion to AD but a negative PIB scan in MCI patients did not exclude future conversion. The results suggest that there is wide individual variation in the brain amyloid load in MCI, and in the course of amyloid accumulation in relation to the clinical diagnosis of AD.

MiR-155-mediated loss of C/EBPβ shifts the TGF-β response from growth inhibition to epithelial-mesenchymal transition, invasion and metastasis in breast cancer

During breast cancer progression, transforming growth factor-beta (TGF-β) switches from acting as a growth inhibitor to become a major promoter of epithelial-mesenchymal transition (EMT), invasion and metastasis. However, the mechanisms involved in this switch are not clear. We found that loss of CCAAT-enhancer binding protein beta (C/EBPβ), a differentiation factor for the mammary epithelium, was associated with signs of EMT in triple-negative human breast cancer, and in invasive areas of mammary tumors in MMTV-PyMT mice. Using an established model of TGF-β-induced EMT in mouse mammary gland epithelial cells, we discovered that C/EBPβ was repressed during EMT by miR-155, an oncomiR in breast cancer. Depletion of C/EBPβ potentiated the TGF-β response towards EMT, and contributed to evasion of the growth inhibitory response to TGF-β. Furthermore, loss of C/EBPβ enhanced invasion and metastatic dissemination of the mouse mammary tumor cells to the lungs after subcutaneous injection into mice. The mechanism by which loss of C/EBPβ promoted the TGF-β response towards EMT, invasion and metastasis, was traced to a previously uncharacterized role of C/EBPβ as a transcriptional activator of genes encoding the epithelial junction proteins E-cadherin and coxsackie virus and adenovirus receptor. The results identify miR-155-mediated loss of C/EBPβ as a mechanism, which promotes breast cancer progression by shifting the TGF-β response from growth inhibition to EMT, invasion and metastasis.

Interaction Support for Visual Comparison Inspired by Natural Behavior

Visual comparison is an intrinsic part of interactive data exploration and analysis. The literature provides a large body of existing solutions that help users accomplish comparison tasks. These solutions are mostly of visual nature and custom-made for specific data. We ask the question if a more general support is possible by focusing on the interaction aspect of comparison tasks. As an answer to this question, we propose a novel interaction concept that is inspired by real-world behavior of people comparing information printed on paper. In line with real-world interaction, our approach supports users (1) in interactively specifying pieces of graphical information to be compared, (2) in flexibly arranging these pieces on the screen, and (3) in performing the actual comparison of side-by-side and overlapping arrangements of the graphical information. Complementary visual cues and add-ons further assist users in carrying out comparison tasks. Our concept and the integrated interaction techniques are generally applicable and can be coupled with different visualization techniques. We implemented an interactive prototype and conducted a qualitative user study to assess the concept's usefulness in the context of three different visualization techniques. The obtained feedback indicates that our interaction techniques mimic the natural behavior quite well, can be learned quickly, and are easy to apply to visual comparison tasks.

Differences in outcomes of oesophageal and gastric cancer surgery across Europe

BACKGROUND

In several European countries, centralization of oesophagogastric cancer surgery has been realized and clinical audits initiated. The present study was designed to evaluate differences in resection rates, outcomes and annual hospital volumes between these countries, and to analyse the relationship between hospital volume and outcomes.

METHODS

National data were obtained from cancer registries or clinical audits in the Netherlands, Sweden, Denmark and England. Differences in outcomes were analysed between countries and between hospital volume categories, adjusting for available case-mix factors.

RESULTS

Between 2004 and 2009, 10 854 oesophagectomies and 9010 gastrectomies were registered. Resection rates in England were 18·2 and 21·6 per cent for oesophageal and gastric cancer respectively, compared with 28·5-29·9 and 41·4-41·9 per cent in the Netherlands and Denmark (P < 0·001). The adjusted 30-day mortality rate after oesophagectomy was lowest in Sweden (1·9 per cent). After gastrectomy, the adjusted 30-day mortality rate was significantly higher in the Netherlands (6·9 per cent) than in Sweden (3·5 per cent; P = 0·017) and Denmark (4·3 per cent; P = 0·029). Increasing hospital volume was associated with a lower 30-day mortality rate after oesophagectomy (odds ratio 0·55 (95 per cent confidence interval 0·42 to 0·72) for at least 41 versus 1-10 procedures per year) and gastrectomy (odds ratio 0·64 (0·41 to 0·99) for at least 21 versus 1-10 procedures per year).

CONCLUSION

Hospitals performing larger numbers of oesophagogastric cancer resections had a lower 30-day mortality rate. Differences in outcomes between several European countries could not be explained by differences in hospital volumes. To understand these differences in outcomes and resection rates, with reliable case-mix adjustments, a uniform European upper gastrointestinal cancer audit with recording of standardized data is warranted.

Perceived information after surgery for colorectal cancer--an explorative study

AIM

With fast track surgery and shorter hospital stay, discharge from hospital after cancer surgery is becoming more challenging for the individual patient. The aim of this study was to explore how patients perceive information after surgery for colorectal cancer, what their information needs are and to determine factors affecting received information.

METHOD

A hundred patients filled in the questionnaires QLQ-C30, CR38 and INFO25 created by the European Organization for Research and Treatment of Cancer, the Eastern Cooperative Oncology Group (ECOG) instrument and the SOC (sense of coherence) instrument and provided written comments within the first 2 weeks after discharge following surgery for colorectal cancer. The questionnaires were analysed using hierarchical cluster analysis and a multiple linear regression analysis. The written comments were analysed using content analysis.

RESULTS

In all, 49% of the patients expressed a need for more information. In the written comments they specified these areas of information: they lacked information concerning their surgery, how to handle symptoms and problems at home, someone to contact after discharge and prognostic information about their future. Patients reported most received information in areas of medical tests and disease but less on other services and support in outpatient care. The variation in INFO25 was best explained by gender (P = 0.045) and preoperative health status (American Society of Anesthesiologists score 3, P = 0.022).

CONCLUSION

The results from this study indicate that women and patients with a poorer preoperative health status scored less on information received and would need more time and support to prepare for discharge. The patients expressed a desire for more information about the surgery, how to handle symptoms at home and prognostic information about their future.

A randomised controlled study of role play in a faculty development programme

BACKGROUND

The Stanford Faculty Development Center at Stanford University has developed a teaching improvement course for medical teachers that has been widely disseminated using a train-the-trainer model.

AIMS

This study was designed to investigate the relative impact of role playing as an instructional technique within that course for facilitating change in teaching behaviours.

METHOD

From January 2009 to April 2010, six faculty development courses were delivered at Uppsala University Hospital to 48 physicians from different departments. The standard course presentation includes a range of instructional methods including short lectures, small group discussion, review of video re-enactments, role-play exercises and personal goal setting. For this study, participants were randomised to participate in (1) a 'standard' course with role play or (2) an 'alternative' course with no role play. The effects of the course on teaching performance were assessed with retrospective pre- and post-course self-ratings of 29 specific teaching behaviours.

RESULTS

Self-assessment ratings indicated significantly greater positive changes in teaching behaviour among faculty who attended the standard course (with role play) as compared to those in the alternative course (p = 0.015).

CONCLUSIONS

This study validates the commonly held view that role play is a useful instructional method for improving teaching.

Understanding social collaboration between actors and technology in an automated and digitised deep mining environment

The purpose of this article is to develop knowledge and learning on the best way to automate organisational activities in deep mines that could lead to the creation of harmony between the human, technical and the social system, towards increased productivity. The findings showed that though the introduction of high-level technological tools in the work environment disrupted the social relations developed over time amongst the employees in most situations, the technological tools themselves became substitute social collaborative partners to the employees. It is concluded that, in developing a digitised mining production system, knowledge of the social collaboration between the humans (miners) and the technology they use for their work must be developed. By implication, knowledge of the human's subject-oriented and object-oriented activities should be considered as an important integral resource for developing a better technological, organisational and human interactive subsystem when designing the intelligent automation and digitisation systems for deep mines. STATEMENT OF RELEVANCE: This study focused on understanding the social collaboration between humans and the technologies they use to work in underground mines. The learning provides an added knowledge in designing technologies and work organisations that could better enhance the human-technology interactive and collaborative system in the automation and digitisation of underground mines.