TLR-mediated aggresome-like induced structures comprise antimicrobial peptides and attenuate intracellular bacterial survival

Immune cells employ diverse mechanisms for host defense. Macrophages, in response to TLR activation, assemble aggresome-like induced structures (ALIS). Our group has shown TLR4-signaling transcriptionally upregulates p62/sequestome1, which assembles ALIS. We have demonstrated that TLR4-mediated autophagy is, in fact, selective-autophagy of ALIS. We hypothesize that TLR-mediated autophagy and ALIS contribute to host-defense. Here we show that ALIS are assembled in macrophages upon exposure to different bacteria. These structures are associated with pathogen-containing phagosomes. Importantly, we present evidence of increased bacterial burden, where ALIS assembly is prevented with p62-specific siRNA. We have employed 3D-super-resolution structured illumination microscopy (3D-SR-SIM) and mass-spectrometric (MS) analyses to gain insight into the assembly of ALIS. Ultra-structural analyses of known constituents of ALIS (p62, ubiquitin, LC3) reveal that ALIS are organized structures with distinct patterns of alignment. Furthermore, MS-analyses of ALIS identified, among others, several proteins of known antimicrobial properties. We have validated MS data by testing the association of some of these molecules (Bst2, IFITM2, IFITM3) with ALIS and the phagocytosed-bacteria. We surmise that AMPs enrichment in ALIS leads to their delivery to bacteria-containing phagosomes and restricts the bacteria. Our findings in this paper support hitherto unknown functions of ALIS in host-defense.

Optomicrofluidic detection of cancer cells in peripheral blood via metabolic glycoengineering

The currently existing label-based techniques for the detection of circulating tumor cells (CTCs) target natural surface proteins of cells and are therefore applicable to only limited cancer cell types. We report optomicrofluidic detection of cancer cells in the pool of peripheral blood mononuclear cells (PBMCs) by exploiting the difference in their cell metabolism. We employ metabolic glycoengineering as a click chemistry tool for tagging cells that yields several fold-higher fluorescence signals from cancer cells compared to that from PBMCs. The effects of concentrations of the tagging compounds and cell incubation time on the fluorescence signal intensity are studied. The tagged cells were encapsulated in droplets ensuring that cells enter the detection region two-dimensionally focused in single-file and optically detected with a high detection efficiency and low coefficient of variation of the signals. The metabolic tagging approach showed a significantly higher tagging efficiency and average fluorescence signal compared to the well-established and widely adopted anti-EpCAM-FITC-based tagging. We demonstrated the detection of three different cancer cell lines - EpCAM-negative cervical cancer cell, HeLa, weakly EpCAM positive, and triple-negative breast cancer cell, MDA-MB-231, and strongly EpCAM positive breast cancer cell, MCF7, highlighting that the proposed technique is independent of naturally occurring cell surface proteins and widely applicable. The metabolically tagged and optically detected cells were successfully recultured, proving the compatibility of the proposed technique with downstream assays. The proposed technique is then utilised for the detection of CTCs in metastatic cancer patients' blood. The current work provides a new strategy for detecting cancer cells in the blood that can find potential applications in both fundamental research and clinical studies involving CTCs as well as in single-cell sequencing.

The British Rhinology Society National COVID-19 Study: Resuming Elective Surgery

Background: As elective services resumed in the aftermath of the first wave of the SARS-CoV-2 pandemic, the British Rhinology Society and Juniors Committees carried out a national prospective study in order to assess and optimise safety and efficacy of surgery. Methodology: Data from 1063 cases was collected from 111 centres in the United Kingdom (excluding Northern Ireland) within the study period (1st June – 14th August 2020), and a three week follow-up period to assess whether there were any cases of SARS-CoV-2 amongst patients and staff. Results: 89.2% of procedures took place in England. 90.6% of patients had minimal comorbidities (ASA Grade 1 or 2). 98.4% of patients were known to have a COVID negative status prior to surgery, with the majority (99.8%) investigated through Viral PCR alone. The most common form of pre-operative shielding was to self-isolate for 14 days (82.5% of cases). 32.6% of cases were performed in an alternative theatre environment, and in 5.3% the private sector was used for NHS patients. In 21.6% of procedures, unfamiliar anaesthetic teams were used, and in 19.2% unfamiliar theatre teams. There was a higher probability of unfamiliar theatre staff or anaesthetist, when operating in an alternative theatre environment. Trainees were not present in theatre in 24.2% of cases. Full PPE (Personal Protective Equipment) was worn by the operating surgeon in 64.1% of cases. No patients or staff were reported to have developed SARS-CoV-2 in the three week period following surgery. Intra-operative challenges were reported in 19.7% of cases and were primarily associated with impaired communication (8.8%) or impaired vision (6.9%). There was a higher chance of challenges reported when unfamiliar theatre teams were present. Conclusions: This data suggests that overall, the resumption of rhinological elective services has been performed safely with no cases of SARS-CoV-2 reported in patients or staff. We must consider the challenges of operating in unfamiliar environments together with surgical and/or anaesthetic teams, as well as the impact on training.

The management of periorbital cellulitis secondary to sinonasal infection: a multicenter prospective study in the United Kingdom

BACKGROUND

Periorbital cellulitis is a potential sight-threatening complication of sinusitis. The majority of patients improve with medical management. Previous studies have suggested significant variations in practice and lack of evidence regarding the optimal management of this condition.

METHODS

A prospective study was conducted over a 12-month period at 8 centers in the United Kingdom assessing the management of patients requiring inpatient treatment for periorbital cellulitis secondary to sinonasal infections.

RESULTS

A total of 143 patients were recruited, of whom 40 were excluded. Of the remaining 103 patients, 5 (4.9%) were diagnosed with neurosurgical complications. This resulted in 98 patients admitted with periorbital cellulitis secondary to an upper respiratory tract infection/sinusitis. A total of 72 were children, of whom 12 (16.7%) required surgical intervention; and of 26 adults, 5 (19.2%) required surgery: the most common antimicrobial regimes administered were intravenous ceftriaxone (with or without metronidazole), and co-amoxiclav. The use of both ceftriaxone and metronidazole from admission was associated with the shortest duration of inpatient stay (3.8 days) in comparison to ceftriaxone alone (5.8 days) or co-amoxiclav (4.5 days) and a reduction in number of patients requiring surgical intervention. There was also an association between the early use of intranasal decongestants and steroids and reduction in requirement for surgical intervention.

CONCLUSION

For a condition where swab and blood cultures are often negative, this study supports the use of ceftriaxone in combination with metronidazole. The administration of intranasal decongestants and corticosteroids correlated with a smaller percentage of those progressing to surgery in those with and without periorbital abscesses.

Quality of Life Outcomes following Treatment of Hypopharyngeal Cancer

Quality of life (QoL) is an important consideration in the management of individuals with head and neck cancer. The poor prognosis and significant impact of treatment modalities on function of the salivary glands, larynx and pharynx combine to make hypopharyngeal carcinoma a particularly challenging condition to treat. The impact of diagnosis and treatment on health related QoL is substantial. There is increased understanding that organ preservation does not necessarily correlate with function preservation as was previously expected. The impact on QoL, of chemoradiotherapy (CRT) or surgery, must be taken into account when managing individuals and deciding on treatment. Several QoL tools have been developed to understand the subjective consequences of functional impairment. The number and quality of studies specifically for hypopharyngeal carcinoma are low. The effects on QoL differ for surgery and CRT, as one would expect, but there are no demonstrable significant differences in most domains. Those treated with CRT show higher levels of dry mouth and sticky saliva, while those patients who have undergone surgery report greater levels of sensory disturbance. Significant differences were not noted in speech outcomes or global (general) health scores. The psychological morbidity and lack of good coping strategies are thought to play an important role in the high suicide rates of these patients (12-fold higher than the average population in the USA). Large, long-term, longitudinal studies of patients surviving treatment, answering both general and disease-specific questionnaires are required to direct clinicians towards the least morbid treatment strategies. The ability to cope and the availability of emotional support probably have a greater impact on subjective QoL than the functional outcomes of treatment.

Does the Technique of Skin Closure Affect the Cosmesis of Cervical Thyroidectomy and Parathyroidectomy Scars? A Review of Literature

The cosmetic outcomes following thyroid and parathyroid surgery is a priority for patients as the surgical scar is in a visible area of the body. Although some have advocated the use of minimally invasive and robotic surgery, these are not without risks and it has been suggested that the scars are not necessarily more favorable. The three most common means of skin closure include the use of subcuticular sutures, clips, and tissue adhesive (with or without deeper subcutaneous sutures) and there are no previous reviews of the published evidence. In this study, the authors compare the cosmetic outcomes through a systematic review of literature. Three studies (n = 200) comparing subcuticular sutures and clips suggest superior cosmetic outcomes with sutures (with statistically significant differences in the immediate postoperative period). Three studies (n = 213) comparing sutures and tissue adhesive show superior outcomes with sutures in the early postoperative period with no differences thereafter. Two studies (n = 202) comparing tissue adhesive and clips do not show that one is superior to the other and show no significant differences. Overall the data are limited; however, the evidence suggests that subcuticular sutures may offer superior cosmetic outcomes than clips and tissue adhesive in conventional thyroid and parathyroid surgery.

Small cell lung cancer presenting as unilateral rhinorrhoea

The metastatic spread of infraclavicular malignancies to the nasal cavity is rare. We describe the case of a 58-year-old man who presented with a 4-month history of right-sided rhinorrhoea, maxillary hypoesthesia, hyposmia and hypogeusia. Clinical examination revealed an irregular mass within the right nasal cavity. Immunohistochemical analyses of biopsies were consistent with small cell carcinoma of indeterminate origin. A positron emission tomography scan demonstrated extensive mediastinal lymphadenopathy with collapse-consolidation of the right lung's middle lobe and no other sites of metastasis. Following discussion at the lung multidisciplinary team meeting, a diagnosis of metastatic small cell lung cancer (SCLC) was made; the patient was staged with N3, M1b disease and palliative chemo-radiotherapy was started. To the best of our knowledge, this report represents the first documented case of a solitary nasal cavity metastasis arising from a SCLC.

Medium-term outcomes of the Universal-2 total wrist arthroplasty in patients with rheumatoid arthritis

AIMS

The aims of this study were to evaluate the clinical and radiological outcomes of the Universal-2 total wrist arthroplasty (TWA) in patients with rheumatoid arthritis.

PATIENTS AND METHODS

This was a retrospective review of all 95 Universal-2 TWAs which were performed in our institution between 2003 to 2012 in patients with rheumatoid arthritis. A total of six patients were lost to follow-up and two died of unrelated causes. A total of ten patients had bilateral procedures. Accordingly, 75 patients (85 TWAs) were included in the study. There were 59 women and 16 men with a mean age of 59 years (26 to 86). The mean follow-up was 53 months (24 to 120). Clinical assessment involved recording pain on a visual analogue score, range of movement, grip strength, the Quick Disabilities of the Arm, Shoulder and Hand (DASH) and Wrightington wrist scores. Any adverse effects were documented with particular emphasis on residual pain, limitation of movement, infection, dislocation and the need for revision surgery. Radiographic assessment was performed pre-operatively and at three, six and 12 months post-operatively, and annually thereafter. Arthroplasties were assessed for distal row intercarpal fusion and loosening. Radiolucent zones around the components were documented according to a system developed at our institution.

RESULTS

The mean worst pain was 8.1 (3 to 10) pre-operatively and 5.4 (0 to 10) at latest follow-up (p < 0.001). Movements were preserved with mean dorsiflexion of 29^o (0 ^o to 70 ^o) and palmar flexion of 21^o (0^o to 50^o). The mean grip strength was 4.8 kg (1.7 to 11.5) pre-operatively and 10 kg (0 to 28) at final follow-up (p < 0.001). The mean QuickDASH and Wrightington wrist scores improved from 61 (16 to 91) to 46 (0 to 89) and 7.9 (1.8 to 10) to 5.7 (0 to 7.8) (p < 0.001). A total of six patients (7%) had major complications; three required revision arthroplasty and three an arthrodesis. The Kaplan-Meier probability of survival using removal of the components as the endpoint was 91% at 7.8 years (95% confidence interval 84 to 91).

CONCLUSION

The Universal-2 TWA is recommended for use in patients with rheumatoid arthritis. Cite this article: Bone Joint J 2016;98-B:1642-7.

Improving the ward-based care of patients post-thyroidectomy

Nursing staff play a crucial role in managing surgical patients in the postoperative period. However, with an increasing risk of subspecialty wards facing closure as a result of financial pressures within the NHS, the knowledge base and expertise of ward-based nursing staff of surgical subspecialties is becoming increasingly limited. Using patients undergoing thyroidectomy as an example, a quality improvement multidisciplinary audit is presented, which shows how simple targeted interventions through a multidisciplinary approach can help maintain high standards of patient care in a secondary care setting.

Compliance of ENT emergency surgery with the Royal College of Surgeons standards

Introduction In 2011 The Royal College of Surgeons of England (RCS) set out best practice standards for emergency surgery. This national pilot audit aimed to determine the compliance of otolaryngology departments in England with these published guidelines. Methods A 26-item online questionnaire was devised that encompassed all the 36 best practices as set out by the RCS for ear, nose and throat (ENT) surgery. This was sent to ENT trainees and consultants based at units in England providing emergency ENT services. Results Data were obtained from 55 of the 102 units (response rate: 54%). A mean compliance of 71% was achieved (range: 25-94%). No units achieved all of the best practices. The standards with the highest compliance included 24-hour availability of blood transfusion and haematology opinion for patients with epistaxis, availability of a consultant or ST3/equivalent for immediate discussion of severe post-tonsillectomy bleeding, 24-hour access to blood transfusion for arrest of haemorrhage and immediate theatre access for arrest of haemorrhage. The areas with the lowest compliance were provision of a pathway for angiography/embolisation for epistaxis and provision of an equipped ENT room on a paediatric ward. Conclusions This audit has highlighted that the majority of departments in England are providing a good standard of ENT emergency care. There is room for improvement in certain areas, such as the provision of an embolisation pathway in the context of refractory epistaxis. We hope that this audit will encourage ENT departments to evaluate their current provision of emergency care and institute changes (where necessary) to maintain and improve their practices.

Ventilation tube insertion simulation: a literature review and validity assessment of five training models

OBJECTIVE

The objective of this study was to identify and investigate the face and content validity of ventilation tube insertion (VTI) training models described in the literature.

DESIGN

A review of literature was carried out to identify articles describing VTI simulators. Feasible models were replicated and assessed by a group of experts.

SETTING

Postgraduate simulation centre.

PARTICIPANTS

Experts were defined as surgeons who had performed at least 100 VTI on patients. Seventeen experts were participated ensuring sufficient statistical power for analysis.

MAIN OUTCOME MEASURES

A standardised 18-item Likert-scale questionnaire was used. This addressed face validity (realism), global and task-specific content (suitability of the model for teaching) and curriculum recommendation.

RESULTS

The search revealed eleven models, of which only five had associated validity data. Five models were found to be feasible to replicate. None of the tested models achieved face or global content validity. Only one model achieved task-specific validity, and hence, there was no agreement on curriculum recommendation.

CONCLUSIONS

The quality of simulation models is moderate and there is room for improvement. There is a need for new models to be developed or existing ones to be refined in order to construct a more realistic training platform for VTI simulation.

Atypical Fibroxanthoma: A case series and review of literature

INTRO/OBJECTIVE

Atypical Fibroxanthoma (AFX) is a rare cutaneous neoplasm arising from myofibroblast or fibroblast-like cells that predominantly affects the head and neck region. It commonly mimics more invasive neoplasms and is a diagnostic challenge to clinicians. The aim of this study was to develop a better understanding of AFX, focusing on recent developments in diagnosis and management.

METHODS

A retrospective case series and review of recent literature were carried out.

RESULTS

Over a 17-year period, seven cases were identified (six male, mean age at presentation was 75.9 years). Two patients underwent complete excision and five patients had curettage and cauterisation. Two patients developed local recurrence but none demonstrated signs suggestive of metastatic spread. Histologically all seven lesions displayed a spindle cell pattern. Where performed, immunohistochemical staining was positive for Vimentin, CD10, CD68 and actin, and negative for CAM 5.2, CD34, Melan-A, S100 protein, HMB45, Cytokeratin A1/A3.

CONCLUSION

Our patient demographics, histopathology and immunohistochemistry are comparable to previous studies. Although advances have been made in immunohistochemical analysis, we are yet to discover a specific diagnostic immunostain for AFX. Clinical findings should therefore be correlated with histology and a panel of immunohistochemical stains should be used. Given the potential for recurrence or metastases, Moh's Micrographic Surgery with regular follow-up may be the preferred management.

Pulmonary dysfunction in children with beta thalassemia major in relation with iron overload - a cross sectional hospital based study

Background: Previously many patients with thalassemia major died from severe anemia during first decade, but with modern transfusion therapy many now survive beyond childhood. Because of such therapy, however excessive iron deposition occurs in lungs and causing respiratory dysfunction. Respiratory impairment occurs because of defective chelation and repeated transfusions. Objectives: To a) study pattern of respiratory impairment using spirometry, b) estimate iron overload by measuring serum ferritin levels, c) correlate a&b. Methodology:Thalassemia children >7year, on regular blood transfusion were included in the study after getting institutional ethical clearance .Standardised pulmonary function test was done using spirometry. Iron overload was assessed using serum ferritin levels. Severity of pulmonary dysfunction was correlated with serum ferritin levels. Results:Total of 42 children were included 62% were males and 38% were females (with median age 12yrs). By spirometry 95% had restrictive pattern of respiratory dysfunction. Mean ferritin value was 4152. Out of them10 (23.8%) mild, 25(59%) moderate and 5(12%) severe dysfunction based on FEV1 and FVC. The mean ferritin values in severe respiratory dysfunction is 6275 which is significantly higher when compared to moderate (4249) and mild (3066) pattern of respiratory dysfunction. None of the children had evidence of CCF. Significant correlation (p value=0.003) was found between severity of pulmonary dysfunction with ferritin values and also with weight of the child (p value=0.007). No other significant correlation found between severity pattern and transfusion index, age or height. Conclusion:Restrictive pattern is most common pulmonary dysfunction seen in chronic iron overloaded thalassemia major children. Regular blood transfusions with adequate chelation decrease incidence of pulmonary dysfunction. Screening of all thalassemia children using spirometry is need of the hour. DOI: http://dx.doi.org/10.3126/ajms.v6i5.11782Asian Journal of Medical Sciences Vol.6(5) 2015 47-50

Oral and maxillofacial surgery in medical schools in the United Kingdom

It has been suggested that oral and maxillofacial surgery (OMFS) is better established in dental schools than in medical schools, and as a result, dental students have a greater insight into the scope of the specialty. We explore how much time is allocated to OMFS in the undergraduate curriculum in medical schools in the UK, and the students' perceptions of the specialty. A total of 186 final year students from 5 medical schools were recruited in a questionnaire-based survey. Of them, 141 (76%) reported no exposure to OMFS, and 37 of the 45 students (82%) who had had some exposure reported that it was not part of their timetabled curriculum. The 2 aspects considered most important by students were the long training pathway (n=38, 20%) and the requirement for dual qualification (n=33, 18%). Our results suggest that UK medical schools provide limited exposure to OMFS. We think it is important that the specialty is included in the compulsory undergraduate curriculum to ensure that medical students gain some awareness. This will not only allow junior doctors to make better informed decisions about their chosen careers, but may also help to reduce the number of inappropriate referrals from doctors in other specialties.

Formation, stability, and mechanical properties of bovine serum albumin stabilized air bubbles produced using coaxial electrohydrodynamic atomization

Bovine serum albumin (BSA) microbubbles were generated using coaxial electrohydrodynamic atomization (CEDHA) using various concentrations of BSA solutions. The bubble characteristics and the long-term stability of the microbubbles were studied through adjustment of processing parameters and the collection media. Bubbles in the range of 40-800 μm were obtained in a controlled fashion, and increasing the flow rate of the BSA solution reduced the polydispersity of the microbubbles. Use of distilled water-glutaraldehyde, glycerol, and glycerol-Tween 80 collection media allowed a remarkable improvement in bubble stability compared to BSA solution collection medium. Possible physical mechanisms were developed to explain the stability of the microbubbles. The collection distance showed a marked influence on stability of the microbubbles. Near-monodisperse particle-reinforced microbubbles were formed with various concentrations of 2,2'-azobis(isobutyramidine) dihydrochloride (AIBA)-polystyrene particle in BSA solution. The bubble size and the size distribution showed negligible change over a period of time irrespective of the concentration of particles at the bubble surface. The compression stiffness of the microbubbles was determined using nanoindentation at ambient temperature and showed that the stiffness of the microbubbles increased from 8 N/m to 20 N/m upon changing the concentration of BSA solution from 5 wt % to 15 wt %.

Cochlear implantation in a patient with combined renal and liver transplantation

OBJECTIVE AND IMPORTANCE

Patients who have undergone solid organ transplantation and continuing immunosuppressant medication are at a higher risk of wound problems and infections following cochlear implantation. This risk is theoretically even further increased in multi-organ transplant recipients due to the increased doses of immunosuppressive medications that these patients are administered.

CLINICAL PRESENTATION AND INTERVENTION

Here, we present the first reported case of successful cochlear implantation in a patient who had previously undergone successful combined liver and kidney transplant. She had no significant complications from the surgery and had good audiological outcomes 3 months post-operatively.

CONCLUSION

As we continue our advances in the use of cochlear implant technology, our report adds to the growing evidence of its benefits in transplant recipients. However, there are important pre- and peri-operative considerations in this group of patients which can improve safety and outcome.

Reducing inappropriate referrals to secondary care: our experiences with the ENT Emergency clinic

INTRODUCTION

In the current financial climate faced by the NHS, it is important that we reduce the amount of inappropriate referrals made to secondary care specialties. ENT Emergency Clinics are one-stop clinics provided by many UK ENT departments to allow more rapid access to ENT services from primary care. However, many referrals to these clinics were considered to be inappropriate, overloading the clinic and delaying referrals to more specialist clinics. We conducted a service improvement project through introduction of referral guidelines and liaising with local GPs.

METHODS

We carried out an initial audit of ENT referrals over a one-month period, which suggested that 31% (69/225) of referrals were inappropriate. We developed a guideline referral proforma that included six specific conditions and details of subspecialist clinics available. This was circulated among GPs and A&E doctors and backed up by hospital teaching sessions. Two months later we repeated the audit.

RESULTS

Following introduction of guidelines there was a significant reduction in inappropriate referrals from 31% (69/225) to 16% (28/179), p<0.01. Despite significant improvements overall, the proportion of inappropriate referrals from GPs remained higher than those from the local A&E department in both Cycle 1 (42% vs.24%, p<0.01) and Cycle 2 (23% vs. 5%, p<0.01).

DISCUSSION AND CONCLUSION

Devising and circulating guideline proformas in conjunction with local education for referring doctors may help reduce the number of inappropriate ENT referrals. This simple and cheap intervention could be used more widely and developed in primary care departments in partnership with local hospitals. Our study also highlights the challenges encountered when introducing new guidelines that affect referrals from doctors in the community. Increasing opportunities for GP trainees to gain some exposure to common conditions presenting to primary care might reduce inappropriate ENT referrals in the future.

Creating "hotels" for cells by electrospinning honeycomb-like polymeric structures

It is well established that three-dimensional honeycomb-like nanofibrous structures enhance cell activity. In this work, we report that electrospun polymer nanofibres self-assemble into three-dimensional honeycomb-like structures. The underlying mechanism is studied by varying the polymer solution concentration, collecting substrates and working distance. The polymer solution concentration has a significant effect on the size of the electrospun nanofibres. The collection substrate and working distance affect the electric field strength, the evaporation of solvent and the discharging of nanofibres and consequently these two had a significant influence on the self-assembly of nanofibres.

Subcellular distribution of the human putative nucleolar GTPase GNL1 is regulated by a novel arginine/lysine-rich domain and a GTP binding domain in a cell cycle-dependent manner

GNL1, a putative nucleolar GTPase, belongs to the MMR1-HSR1 family of large GTPases that are emerging as crucial coordinators of signaling cascades in different cellular compartments. Members of this family share very closely related G-domains, but the signals and pathways regulating their subcellular localization with respect to cell growth remain unknown. To understand the nuclear transport mechanism of GNL1, we have identified a novel arginine/lysine-rich nucleolar localization signal in the NH(2)-terminus that is shown to translocate GNL1 and a heterologous protein to the nucleus/nucleolus in a pathway that is independent of importin-α and importin-β. In addition, the present investigation provided evidence that GNL1 localized to the nucleus and the nucleolus only in G2 stage, in contrast to its cytoplasmic localization in the G1 and S phases of the cell cycle. Using heterokaryon assay, we have demonstrated that GNL1 shuttles between the nucleus and the cytoplasm and that the motif between amino acids 201 and 225 is essential for its export from the nucleus by a signal-mediated CRM1-independent pathway. Alanine-scanning mutagenesis of conserved residues within G-domains suggests that the G2 motif is critical for guanine nucleotide triphosphate (GTP) binding of GNL1 and further showed that nucleolar retention of GNL1 is regulated by a GTP-gating-mediated mechanism. Expression of wild-type GNL1 promotes G2/M transition, in contrast to the G-domain mutant (G2m), which fails to localize to the nucleolus. These data suggest that nucleolar translocation during G2 phase may be critical for faster M-phase transition during cell proliferation. Replacement of conserved residues within the G5 motif alters the stability of GNL1 without changing GTP binding activity. Finally, our data suggest that ongoing transcription is essential for the efficient localization of GNL1 to the nucleolus. Overall, the results reported here demonstrate that multiple mechanisms are involved in the translocation of GNL1 to the nucleolus in a cell cycle-dependent manner to regulate cell growth and proliferation.

Duration of Ross River viraemia in a mouse model--implications for transfusion transmission

BACKGROUND AND OBJECTIVES

There is little data on the duration of viraemia following infection with Ross River virus (RRV), the most common cause of arbovirus disease in Australia. In particular, no accurate estimate exists for the duration of pre-symptomatic RRV infection, which is important in assessing the potential for transfusion transmission.

MATERIALS AND METHODS

We used an established mouse model of RRV infection involving adult Swiss outbred mice to measure viraemia following infection. Applying our experimental data to a published probabilistic model for estimating the risk of dengue transmission by transfused blood, we derived comparable risk estimates for RRV.

RESULTS

Ross River virus RNA was measured using highly sensitive real-time PCR in serum samples to determine the duration of asymptomatic viraemia, which typically lasted 5 days, but extended to 9 days in some mice. Assuming the potential for transfusion transmission is proven, the risk of RRV transmission by blood during a 2004 outbreak in Cairns, Australia was retrospectively estimated as 1 in 13,542 (range from 1 in 4765 to 47,563).

CONCLUSION

This study provides updated epidemiological data useful to underpin modelling to assess the potential risk of transfusion-transmitted RRV. Using an established model for dengue, the risk estimate for RRV transmission is comparable in the same geographical region. Should transfusion be proven as a route of transmission, this supports consideration of appropriate mitigation strategies to safeguard blood recipients.

Mechanism of host cell MAPK/ERK-2 incorporation into lentivirus particles: characterization of the interaction between MAPK/ERK-2 and proline-rich-domain containing capsid region of structural protein Gag

The characteristic event that follows infection of a cell by retroviruses Including human immunodeficiency virus (HIV)/ simian immunodeficiency virus (SIV) is the formation of a reverse transcription complex in which viral nucleic acids are synthesized. Nuclear transport of newly synthesized viral DNA requires phosphorylation of proteins in the reverse transcription complex by virion-associated cellular kinases. Recently, we demonstrated that disruption of cellular mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase 2 (ERK-2) incorporation into SIV virions inhibits virus replication in nonproliferating target cells, indicating that MAPK/ERK-2 plays an important role in HIV /SIV replication. The mechanism of incorporation of MAPK/ERK-2 into virus particles is not defined. In this regard, we hypothesized that a likely interaction of MAPK/ERK-2 with Gag(p55) may enable its packaging into virus particles. In the present investigation, we provided evidence for the first time that MAPK/ERK-2 interacts with the structural Gag polyprotein p55 using a combination of mutagenesis and protein-protein interaction analysis. We further show that MAPK/ERK-2 interacts specifically with the poly-proline motif present in the capsid region of Gag(p55). Utilizing virus-like particles directed by Gag, we have shown that the exchange of conserved proline residues within capsid of Gag(p55) resulted in impaired incorporation of MAPK/ERK-2. In addition, the deletion of a domain comprising amino acids 201 to 255 within host cell MAPK/ERK-2 abrogates its interaction with Gag(p55). The relevance of the poly-proline motif is further evident by its conservation in diverse retroviruses, as noted from the sequence analysis and structural modeling studies of predicted amino acid sequences of the corresponding Gag proteins. Collectively, these data suggest that the interaction of MAPK/ERK-2 with Gag polyprotein results in its incorporation into virus particles and may be essential for retroviral replication.

Extracellular signal-regulated kinase 2 (ERK-2) mediated phosphorylation regulates nucleo-cytoplasmic shuttling and cell growth control of Ras-associated tumor suppressor protein, RASSF2

Ras GTPase controls the normal cell growth through binding with an array of effector molecules, such as Raf and PI3-kinase in a GTP-dependent manner. RASSF2, a member of the Ras association domain family, is known to be involved in the suppression of cell growth and is frequently down-regulated in various tumor tissues by promoter hypermethylation. In the present study, we demonstrate that RASSF2 shuttles between nucleus and cytoplasm by a signal-mediated process and its export from the nucleus is sensitive to leptomycin B. Amino acids between 240 to 260 in the C-terminus of RASSF2 harbor a functional nuclear export signal (NES), which is necessary and sufficient for efficient export of RASSF2 from the nucleus. Substitution of conserved Ile254, Val257 and Leu259 within the minimal NES impaired RASSF2 export from the nucleus. In addition, wild type but not the nuclear export defective RASSF2 mutant interacts with export receptor, CRM-1 and exported from the nucleus. Surprisingly, we observed nucleolar localization for the nuclear export defective mutant suggesting the possibility that RASSF2 may localize in different cellular compartments transiently in a cell cycle dependent manner and the observed nuclear localization for wild type protein may be due to faster export kinetics from the nucleolus. Furthermore, our data suggest that RASSF2 is specifically phosphorylated by MAPK/ERK-2 and the inhibitors of MAPK pathway impair the phosphorylation and subsequently block the export of RASSF2 from the nucleus. These data clearly suggest that ERK-2 mediated phosphorylation plays an important role in regulating the nucleo-cytoplasmic shuttling of RASSF2. Interestingly, nuclear import defective mutant of RASSF2 failed to induce cell cycle arrest at G1/S phase and apoptosis suggesting that RASSF2 regulates cell growth in a nuclear localization dependent manner. Collectively, these data provided evidence for the first time that MAPK/ERK-2 mediated phosphorylation regulates nucleo-cytoplasmic transport and cell growth arrest activity of RASSF2. Taken together, the present study suggests that active transport between nucleus and cytoplasm may constitute an important regulatory mechanism for RASSF2 function.

Interleukin-15 mediates potent antiviral responses via an interferon-dependent mechanism

Interleukin-15 (IL-15) is a potent growth factor for activated T and natural killer (NK) cells, stimulator of memory T cells and plays an important role in viral immunity. To investigate mechanisms underlying the antiviral activity of IL-15, a recombinant vaccinia virus (rVV) encoding murine IL-15 (VV-IL-15) was constructed. Following infection of mice with VV-IL-15, virus titres in the ovaries were significantly reduced compared to mice infected with control VV. Growth of VV-IL-15 was also reduced in nude athymic mice, indicating the antiviral activity of IL-15 does not require T cells. Additionally, VV-IL-15 augmented the cytolytic activity of natural NK cells in the spleen and enhanced interferon (IFN) mRNA expression and transcription factors associated with IFN induction. Using knockout mice and antibody depletion studies, we showed for the first time that the control of VV-IL-15 replication in mice is dependent on NK cells and IFNs and, in their absence, the protective role of IL-15 is abolished.

Mechanism of interleukin-25 (IL-17E)-induced pulmonary inflammation and airways hyper-reactivity

BACKGROUND

IL-25, a novel member of the IL-17 cytokine family, promotes CD4+ T-helper 2 lymphocyte-like (Th type-2) inflammatory responses in the lung. Although IL-25 up-regulates IL-13 in the lung, the contribution of this and other type 2 cytokine signalling pathways to the induction and persistence of airways hyper-reactivity (AHR) and allergic inflammation are unclear.

OBJECTIVE

To determine the downstream factors employed by IL-25 to induce Th type-2 pulmonary inflammation and AHR.

METHODS

IL-25 was delivered to the airways of BALB/c mice by intra-tracheal (i.t.) instillation and AHR and Th type-2 inflammatory responses were characterized in wild type (WT) and Th type-2-cytokine and -signalling pathway-deficient (-/-) mice.

RESULTS

IL-25 treatment resulted in AHR, eosinophilic inflammation, mucus hypersecretion and a progressive increase in the production of Th type-2 cytokines in the lungs. Levels of arginase-I (arg-I) and eotaxin were also elevated by IL-25 treatment. A significant reduction in AHR, and attenuation of mucus production was observed in IL-25-treated IL-13-/-, IL-4 receptor alpha (IL-4Ralpha-/-)- and signal-transducer-and-activator-of-transcription-factor-6 (STAT6-/-)-deficient mice. AHR was also inhibited in IL-4(-/-)- and IL-5/eotaxin(1)(-/-)- deficient mice treated with IL-25, however, mucus hypersecretion was not completely ablated. IL-25 promoted Th type-2 responses by directly acting on naïve T cells.

CONCLUSION

IL-25 potently (single dose) induces sustained AHR and acute pulmonary inflammation with eosinophilia. IL-25-induced AHR is dependent on the production of Th type-2 cytokines, and removal of IL-13 and its signal transduction pathway prevents IL-25-induced airways inflammation and AHR. IL-25 potently induces inflammatory cascades that may exacerbate allergic airways inflammation by promoting Th type-2 cytokine responses in conjunction with the up-regulation of factors (eotaxin and arg-I) that can amplify inflammation associated with allergic disorders. Dysregulation in IL-25 production may predispose to features of allergic airways disease.