GSK2556286 Is a Novel Antitubercular Drug Candidate Effective In Vivo with the Potential To Shorten Tuberculosis Treatment.

As a result of a high-throughput compound screening campaign using Mycobacterium tuberculosis-infected macrophages, a new drug candidate for the treatment of tuberculosis has been identified. GSK2556286 inhibits growth within human macrophages (50% inhibitory concentration [IC50] = 0.07 µM), is active against extracellular bacteria in cholesterol-containing culture medium, and exhibits no cross-resistance with known antitubercular drugs. In addition, it has shown efficacy in different mouse models of tuberculosis (TB) and has an adequate safety profile in two preclinical species. These features indicate a compound with a novel mode of action, although still not fully defined, that is effective against both multidrug-resistant (MDR) or extensively drug-resistant (XDR) and drug-sensitive (DS) M. tuberculosis with the potential to shorten the duration of treatment in novel combination drug regimens. (This study has been registered at ClinicalTrials.gov under identifier NCT04472897).

Diagnostic Utility of C4d by Direct Immunofluorescence in Bullous Pemphigoid.

ABSTRACT: Bullous pemphigoid (BP) is an autoimmune blistering disease that commonly affects elderly patients. Direct immunofluorescence (DIF) for immunoglobulin G (IgG) and C3c on frozen skin biopsies is the gold standard for the diagnosis of BP. In a minority of cases, IgG and/or C3c are found negative, and in these situations, there is a need for a more stable diagnostic marker of BP. C4d is biologically inactive, but has a long half-life, rendering it a long-lived marker for antibody-mediated complement activation. Previous studies already demonstrated that C4d was diagnostically useful in formalin-fixed paraffin-embedded skin biopsies of patients with BP. We hypothesized that C4d detected by DIF could also be a promising diagnostic marker for BP, particularly in IgG and/or C3c DIF-negative cases. In this single-center retrospective study, 69 cases of BP were analyzed for linear deposition of C4d; of the 69 cases, n = 26 were IgG+/C3c-, n = 10 IgG+/C3c+, and n = 33 IgG-/C3c-. Results were compared with n = 39 negative controls. Seven of the 26 (27%) IgG+/C3c- and 3 of the 33 (9%) IgG-/C3c- BP cases were positive for C4d. All 10 IgG+/C3c+ cases were also C4d positive. In the negative control group, 2 of the 39 (5%) were found positive for C4d. In conclusion, the current study shows that C4d is a more sensitive but not a 100% specific marker of BP. We conclude that C4d by DIF could be an interesting diagnostic adjunct for BP, particularly in IgG-/C3c- double negative cases.

Combination of a mitogen-activated protein kinase inhibitor with the tyrosine kinase inhibitor pacritinib combats cell adhesion-based residual disease and prevents re-expansion of FLT3-ITD acute myeloid leukaemia.

Minimal residual disease (MRD) in acute myeloid leukaemia (AML) poses a major challenge due to drug insensitivity and high risk of relapse. Intensification of chemotherapy and stem cell transplantation are often pivoted on MRD status. Relapse rates are high even with the integration of first-generation FMS-like tyrosine kinase 3 (FLT3) inhibitors in pre- and post-transplant regimes and as maintenance in FLT3-mutated AML. Pre-clinical progress is hampered by the lack of suitable modelling of residual disease and post-therapy relapse. In the present study, we investigated the nature of pro-survival signalling in primary residual tyrosine kinase inhibitor (TKI)-treated AML cells adherent to stroma and further determined their drug sensitivity in order to inform rational future therapy combinations. Using a primary human leukaemia-human stroma model to mimic the cell-cell interactions occurring in patients, the ability of several TKIs in clinical use, to abrogate stroma-driven leukaemic signalling was determined, and a synergistic combination with a mitogen-activated protein kinase (MEK) inhibitor identified for potential therapeutic application in the MRD setting. The findings reveal a common mechanism of stroma-mediated resistance that may be independent of mutational status but can be targeted through rational drug design, to eradicate MRD and reduce treatment-related toxicity.

Current practice on the management of pre-operative urine dipstick results in women undergoing gynaecological surgery in Wales.

A survey was circulated to consultant gynaecologists across Wales, to evaluate the management of pre-operative urine dipstick results. Questions were based on NICE guideline 171, regarding the management of urinary incontinence in women. Six respondents never checked their patient's urine dipstick results. Of the remaining 37 respondents, 70% always check and 30% sometimes check. Overall, 37.1% cancelled surgery when a urine dipstick was positive for either nitrite or leukocyte-esterase (LE). A significantly larger proportion cancelled surgery when symptomatic for urinary tract infection (p< 0.001), and when nitrite and LE positive compared to only LE positive (p< 0.05). This survey provides evidence that gynaecological operations are potentially being cancelled unnecessarily based on a screening test with limited sensitivity and specificity. Further research is needed into the outcomes of gynaecological surgery in women symptomatic of urinary tract infection to provide guidance on the use of pre-operative urinalysis and the management of test results. Impact statement What is already known on this subject? The strongest risk factor for postoperative urinary tract infections (UTIs) is a pre-operative recurrent UTI (Nygaard et al. 2011 ). This is the reason behind the urine dipstick being part of the pre-operative checklist for gynaecological surgery. Traditionally, a suspected UTI would mean postphoning surgery whilst treating the UTI. It is known that the sensitivity of the nitrite test and leukocyte-esterase test when used alone is low and cannot rule out UTI in most patients (Mambatta et al. 2015 ). Urine culture is therefore suggested for all patients with a suspected UTI (John et al. 2006 ). To our knowledge, there are no data available on whether we should be postphoning gynaecological surgery based on a urine dipstick result. What the results of this study add? Overall, 37.1% of respondents cancelled surgery when a pre-operative urine dipstick was positive for either nitrite or leukocyte-esterase. This provides evidence of variation in the practice of using the urine dipstick in women undergoing gynaecological surgery in Wales. These cancellations are potentially unnecessarily. Furthermore, 14% of respondents did not use a urine dipstick and the majority did not act on an abnormal results, implying clinicians have a low confidence in the test as a screening tool. What the implications are of these findings for clinical practice and/or further research? We propose removing the urine dipstick as a pre-operative screening test. Asymptomatic bacteriuria is common in women and routine screening for UTI pre-operatively will therefore inevitably lead to unnecessary intervention (i.e. cancellation). Further research is needed into the outcomes of gynaecological surgery in women symptomatic of UTI to be able to provide guidance on the use of pre-operative urinalysis and management of the test results.

Pilot qualitative exploration of the impact of community asset mapping within the undergraduate psychiatry curriculum at an Irish medical school.

INTRODUCTION: Providing an effective response to global health disparities requires that future doctors are better prepared to embrace a public health ethos. Asset-based approaches see people and communities as coproducers of health and well-being and have begun to influence healthcare policy and the training of health professionals. However, to date, there is scant research in this area within undergraduate medical education. OBJECTIVES: To explore: (1) whether an asset-mapping assignment enhances medical students' experience and understanding of psychiatry. (2) The extent to which asset mapping promotes engagement of students with the clinical teams and communities in which they are placed, as perceived by students, clinical tutors and other team members. DESIGN: Using a qualitative case study approach, semistructured interviews were completed with 16 students, 8 psychiatry tutors and 3 multidisciplinary team members (MDTMs) to explore their experiences of the initiative. Interview transcripts were thematically analysed, based on the study aims. SETTING: This research was carried out at Ireland's largest medical school, among undergraduate medical students following a 6-week psychiatry clerkship. INTERVENTION: Students completed a team-based assignment to elicit information on community assets from patients and presented an asset map to their host clinical team at the end of the clerkship. RESULTS: We identified three over-arching themes within the data: (a) connecting the individual patient with the community; (b) relationship building; and (c) pedagogical challenges and rewards. Students found the asset-mapping assignment not only challenging but also rewarding and supported its retention within the curriculum. Tutors were predominantly positive, but some felt that the social focus diluted students' professional identity. MDTMs welcomed the initiative and wished to be more involved. CONCLUSION: Our findings suggest that community asset mapping offers added value within the undergraduate medical curriculum, sensitising students to the importance of exploring patient-perceived community assets.

The Africa non-communicable diseases (NCD) Open Lab: Impact of a portfolio of clinical studies to deepen the understanding of NCDs in sub-Saharan Africa.

Background: Clinical research in sub-Saharan Africa (SSA) has often focussed on communicable diseases. However, with the increasing burden of non-communicable diseases (NCDs), there is a need for Africa-specific NCD research. Methods: GSK established the Africa NCD Open Lab in 2014. Three calls for proposals were advertised through various media channels. An external independent scientific advisory board, predominantly representing African scientists and NCD experts, reviewed and selected projects to receive funding. An additional programme in the Africa NCD Open Lab was designed to build statistical capability by supporting training initiatives. We assessed the impact of the Africa NCD Open Lab in three ways: scientific quality with impact; research training and professional development; and research environments. We captured metrics through regular reports/interactions with researchers; via a final report; and through exit interviews with principal investigators. Results: Twenty projects in 11 African countries were funded; reports from 18 completed projects are available (data capture is ongoing). Overall, 139 articles have been published in peer-reviewed journals and other data have been presented at conferences and other forums. Most completed projects led to positive outcomes, such as further research, informing policy, or positively impacting clinical care, including three projects that saw changes to regional or national practice guidelines: the CREOLE study in Nigeria; the African Severe Asthma Program in Uganda; and the African Prospective Study on the Early Detection and Identification of Cardiovascular Disease and Hypertension in South Africa. Participation in the Africa NCD Open Lab led to the award of 34 grants related to or influenced by increased research capacity or experience. Significant professional development related to the projects also occurred with higher-level degrees being awarded, including 30 MScs, 30 PhDs, and nine postdoctoral fellowships. Through these projects, research capacity was strengthened across the region by equipping core research facilities, training research staff, strengthening research support services, and supporting the expansion of investigator networks. Conclusions: The completed Africa NCD Open Lab projects demonstrate high-quality research outcomes addressing important health challenges with potential benefits to African populations. Based on the success of the Africa NCD Open Lab, additional funding has been secured to extend the Open Lab initiative.

A first-in-class leucyl-tRNA synthetase inhibitor, ganfeborole, for rifampicin-susceptible tuberculosis: a phase 2a open-label, randomized trial.

New tuberculosis treatments are needed to address drug resistance, lengthy treatment duration and adverse reactions of available agents. GSK3036656 (ganfeborole) is a first-in-class benzoxaborole inhibiting the Mycobacterium tuberculosis leucyl-tRNA synthetase. Here, in this phase 2a, single-center, open-label, randomized trial, we assessed early bactericidal activity (primary objective) and safety and pharmacokinetics (secondary objectives) of ganfeborole in participants with untreated, rifampicin-susceptible pulmonary tuberculosis. Overall, 75 males were treated with ganfeborole (1/5/15/30 mg) or standard of care (Rifafour e-275 or generic alternative) once daily for 14 days. We observed numerical reductions in daily sputum-derived colony-forming units from baseline in participants receiving 5, 15 and 30 mg once daily but not those receiving 1 mg ganfeborole. Adverse event rates were comparable across groups; all events were grade 1 or 2. In a participant subset, post hoc exploratory computational analysis of 18F-fluorodeoxyglucose positron emission tomography/computed tomography findings showed measurable treatment responses across several lesion types in those receiving ganfeborole 30 mg at day 14. Analysis of whole-blood transcriptional treatment response to ganfeborole 30 mg at day 14 revealed a strong association with neutrophil-dominated transcriptional modules. The demonstrated bactericidal activity and acceptable safety profile suggest that ganfeborole is a potential candidate for combination treatment of pulmonary tuberculosis.ClinicalTrials.gov identifier: NCT03557281 .

Are We Ever Going Back? Exploring the Views of Health Professionals on Postpandemic Continuing Professional Development Modalities.

INTRODUCTION: The COVID-19 pandemic has profoundly altered the ways in which health care professionals engage with continuing professional development (CPD), but the extent to which these changes are permanent remains unknown at present. This mixed-methods research aims to capture the perspectives of health professionals on their preferences for CPD formats, including the conditions that inform preferences for in-person and online CPD events and the optimum length and type of online and in-person events. METHODS: A survey was used to gain a high-level perspective on health professionals' engagement with CPD, areas of interest, and capabilities and preferences in relation to online formats. A total of 340 health care professionals across 21 countries responded to the survey. Follow-up semistructured interviews were conducted with 16 respondents to gain deeper insights into their perspectives. RESULTS: Key themes include CPD activity before and during COVID, social and networking aspects, access versus engagement, cost, and time and timing. DISCUSSION: Recommendations regarding the design of both in-person and online events are included. Beyond merely moving in-person events online, innovative design approaches should be adopted to capitalize on the affordances of digital technologies and enhance engagement.

Machine Learning and Pharmacometrics for Prediction of Pharmacokinetic Data: Differences, Similarities and Challenges Illustrated with Rifampicin.

Pharmacometrics (PM) and machine learning (ML) are both valuable for drug development to characterize pharmacokinetics (PK) and pharmacodynamics (PD). Pharmacokinetic/pharmacodynamic (PKPD) analysis using PM provides mechanistic insight into biological processes but is time- and labor-intensive. In contrast, ML models are much quicker trained, but offer less mechanistic insights. The opportunity of using ML predictions of drug PK as input for a PKPD model could strongly accelerate analysis efforts. Here exemplified by rifampicin, a widely used antibiotic, we explore the ability of different ML algorithms to predict drug PK. Based on simulated data, we trained linear regressions (LASSO), Gradient Boosting Machines, XGBoost and Random Forest to predict the plasma concentration-time series and rifampicin area under the concentration-versus-time curve from 0-24 h (AUC0-24h) after repeated dosing. XGBoost performed best for prediction of the entire PK series (R2: 0.84, root mean square error (RMSE): 6.9 mg/L, mean absolute error (MAE): 4.0 mg/L) for the scenario with the largest data size. For AUC0-24h prediction, LASSO showed the highest performance (R2: 0.97, RMSE: 29.1 h·mg/L, MAE: 18.8 h·mg/L). Increasing the number of plasma concentrations per patient (0, 2 or 6 concentrations per occasion) improved model performance. For example, for AUC0-24h prediction using LASSO, the R2 was 0.41, 0.69 and 0.97 when using predictors only (no plasma concentrations), 2 or 6 plasma concentrations per occasion as input, respectively. Run times for the ML models ranged from 1.0 s to 8 min, while the run time for the PM model was more than 3 h. Furthermore, building a PM model is more time- and labor-intensive compared with ML. ML predictions of drug PK could thus be used as input into a PKPD model, enabling time-efficient analysis.

Exome sequencing of individuals with Huntington's disease implicates FAN1 nuclease activity in slowing CAG expansion and disease onset.

The age at onset of motor symptoms in Huntington's disease (HD) is driven by HTT CAG repeat length but modified by other genes. In this study, we used exome sequencing of 683 patients with HD with extremes of onset or phenotype relative to CAG length to identify rare variants associated with clinical effect. We discovered damaging coding variants in candidate modifier genes identified in previous genome-wide association studies associated with altered HD onset or severity. Variants in FAN1 clustered in its DNA-binding and nuclease domains and were associated predominantly with earlier-onset HD. Nuclease activities of purified variants in vitro correlated with residual age at motor onset of HD. Mutating endogenous FAN1 to a nuclease-inactive form in an induced pluripotent stem cell model of HD led to rates of CAG expansion similar to those observed with complete FAN1 knockout. Together, these data implicate FAN1 nuclease activity in slowing somatic repeat expansion and hence onset of HD.

SB-742457 and donepezil in Alzheimer disease: a randomized, placebo-controlled study.

OBJECTIVE: To estimate the treatment effects of SB-742457 and donepezil in Alzheimer disease (AD) in a contemporary clinical trial. METHOD: Randomized, controlled, parallel-group, exploratory study with a 4-week, single-blind, placebo run-in phase and 24-week, double-blind treatment phase. Primary endpoints were Clinician's Interview-Based Impression of Change with caregiver input (CIBIC+) and the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-Cog). RESULTS: One hundred ninety eight subjects with mild-to-moderate probable AD (MMSE scores 12-26) were randomized; 196 were included in the intent-to-treat population (placebo, n = 61; SB-742457 35 mg/day, n = 68; donepezil 10 mg/day, n = 67), and 161 completed. Drug-placebo treatment differences in CIBIC+ score at week 24 were -0.17 (90% confidence interval [CI]: -0.50, 0.16) for SB-742457 and -0.28 (90% CI: -0.61, 0.05) for donepezil. Drug-placebo treatment differences (90% CI) in change from baseline ADAS-Cog score at Week 24 were -0.4 (-2.2, 1.4) for SB-742457 and -1.2 (-3.0, 0.6) for donepezil. All treatments were generally safe and well tolerated. CONCLUSIONS: In this exploratory study, SB-742457 and donepezil were associated with improvements in global function. Treatment effect on cognition for both SB-742457 and donepezil was smaller than those previously observed in previous clinical studies with donepezil.

Scientific issues related to Codex Alimentarius goals: a review of principles, with examples.

The Codex Alimentarius provides the food standards and guidelines recognized by the World Trade Organization as the primary authority for use in settlement of related trade disputes. Codex bases its decisions primarily on scientific principles and evidence, although other legitimate factors such as economic and societal values may be considered. Codex has two primary aims: to protect consumers' health and assure fair practices in food trade. Codex documents may provide templates for individual nations but are not binding for domestic policies. Despite many advances over the last couple of decades, misunderstandings and controversies have interfered with important aspects of progress which Codex needs to accomplish, especially in the areas of claims of benefits related to food or nutrient consumption and the establishment of the safety of these items. Claims for health benefits should be based on the totality of available scientific evidence, including observational data collected from large populations as well as the results from randomized clinical trials. Safety should be evaluated by risk assessment on high quality experimental data, with anecdotal information having a lesser role. Regulatory policy would be improved if "history of safe use" were to be better defined and described.

Novel wireless sensor system for monitoring oxygen, temperature and respiration rate of horticultural crops post harvest.

In order to design optimal packages, it is of pivotal importance to determine the rate at which harvested fresh fruits and vegetables consume oxygen. The respiration rate of oxygen (RRO2) is determined by measuring the consumed oxygen per hour per kg plant material, and the rate is highly influenced by temperature and gas composition. Traditionally, RRO2 has been determined at discrete time intervals. In this study, wireless sensor networks (WSNs) were used to determine RRO2 continuously in plant material (fresh cut broccoli florets) at 5 °C, 10 °C and 20 °C and at modified gas compositions (decreasing oxygen and increasing carbon dioxide levels). Furthermore, the WSN enabled concomitant determination of oxygen and temperature in the very close vicinity of the plant material. This information proved a very close relationship between changes in temperature and respiration rate. The applied WSNs were unable to determine oxygen levels lower than 5% and carbon dioxide was not determined. Despite these drawbacks in relation to respiration analysis, the WSNs offer a new possibility to do continuous measurement of RRO2 in post harvest research, thereby investigating the close relation between temperature and RRO2. The conclusions are that WSNs have the potential to be used as a monitor of RRO2 of plant material after harvest, during storage and packaging, thereby leading to optimized consumer products.

Modelling condensation and the initiation of chondrogenesis in chick wing bud mesenchymal cells levitated in an ultrasound trap.

Chick wing bud mesenchymal cell micromass culture allows the study of a variety of developmental mechanisms, ranging from cell adhesion to pattern formation. However, many cells remain in contact with an artificial substratum, which can influence cytoskeletal organisation and differentiation. An ultrasound standing wave trap facilitates the rapid formation of 2-D monolayer cell aggregates with a defined zero time-point, independent from contact with a surface. Aggregates formed rapidly (within 2 min) and intercellular membrane spreading occurred at points of contact. This was associated with an increase in peripheral F-actin within 10 min of cell-cell contact and aggregates had obtained physical integrity by 30 min. The chondrogenic transcription factor Sox9 could be detected in cells in the ultrasound trap within 3 h (ultrasound exposure alone was not responsible for this effect). This approach facilitates the study of the initial cell-cell interactions that occur during condensation formation and demonstrates that a combination of cell shape and cytoskeletal organisation is required for the initiation and maintenance of a differentiated phenotype, which is lost when these phenomena are influenced by contact with an artificial substrate.

Do women seeking care from obstetrician-gynaecologists prefer to see a female or a male doctor?

PURPOSE: To examine whether women seeking care from obstetrician-gynaecologists prefer to see a female or a male doctor or have no preference. METHODS: Five hundred consecutive women attending gynaecology and antenatal clinics were asked to complete a survey questionnaire containing 12 items requiring opinion on whether they want to be seen by a female or male obstetrician-gynaecologist or have no preference. It also contained questions regarding their reasons for the stated preference. RESULTS: Of the consecutive 500 patients that were given the questionnaire, 435 responded (87% response rate). Two hundred and twenty-five patients had no preference, 194 patients preferred female obstetrician-gynaecologist and 16 patients preferred male obstetrician-gynaecologist. The reasons stated by women who preferred to see a female doctor were as follows: religious beliefs-5%, understands problems better-48%, unspecified reasons-6%, issues of personal modesty-41%. All 16 women who preferred to see a male doctor stated the reason as 'understands problems better' (100%). CONCLUSIONS: The majority of women expressed no preference to either gender of their obstetrician and gynaecologists, but significant proportion of the remainder would prefer to see a female doctor when given the choice. Although women gave a variety of subjective reasons for this, demographically it appears that women who are less educated with lower income and being non-white are more likely to prefer to see a female doctor.

Complement Activation in Autoimmune Bullous Dermatoses: A Comprehensive Review.

Autoimmune bullous dermatoses (AIBD) are characterized by circulating autoantibodies that are either directed against epidermal antigens or deposited as immune complexes in the basement membrane zone (BMZ). The complement system (CS) can be activated by autoantibodies, thereby triggering activation of specific complement pathways. Local complement activation induces a pathogenic inflammatory response that eventually results in the formation of a sub- or intraepidermal blister. Deposition of complement components is routinely used as a diagnostic marker for AIBD. Knowledge from different animal models mimicking AIBD and deposition of complement components in human skin biopsies provides more insight into the role of complement in the pathogenesis of the different AIBD. This review outlines the role of the CS in several AIBD including bullous pemphigoid, epidermolysis bullosa acquisita, mucous membrane pemphigoid (MMP), pemphigus, linear IgA-disease, and dermatitis herpetiformis. We also discuss potential therapeutic approaches targeting key complement components, pathways and pathogenic complement-mediated events.

Predictors of placebo group decline in the Alzheimer's disease Assessment Scale-cognitive subscale (ADAS-Cog) in 24 week clinical trials of Alzheimer's disease.

One limitation of several recent 24 week Alzheimer's disease (AD) clinical trials was the lack of cognitive decline detected by the AD Assessment Scale-cognitive subscale (ADAS-cog) in the placebo groups, possibly obscuring true medication effects. Data from 733 individuals in the placebo arms of six AD clinical trials performed 1996-1997 were pooled to examine the relationship of clinical, demographic, and genetic characteristics with the 24 week change in ADAS-cog. Baseline cognitive and functional status and the screening-to-baseline change in ADAS-cog were the strongest independent predictors of the 24 week change in ADAS-cog. The ADAS-cog did not detect progression in patients with mild dementia (screening Mini-Mental State Exam, MMSE, >or=20). The change in ADAS-cog from screening to baseline was inversely correlated with the 24 week change score; it was more difficult to detect cognitive decline at 24 weeks if individuals markedly worsened from screening to baseline. The effects of baseline MMSE and screening-to-baseline change in ADAS-cog generalized to the placebo group (N=106) of another AD study performed in 2004-2005. Overcoming lack of placebo decline in AD clinical trials will require scales more sensitive to cognitive decline in mild AD and strategies to reduce within-person variability in outcome measures.

A quantitative inverse relationship between connexin32 expression and cell proliferation in a rat hepatoma cell line.

Gap junctions comprised of connexin proteins are involved in direct intercellular communication and the regulation of cell behaviour and homeostasis. Reduced connexin expression and loss of gap junction function is a characteristic of many cancer cells and of the effect of many non-genotoxic carcinogens that induce cell proliferation. Moreover, when certain cancer cell lines are transfected with specific connexin genes, cells can regain control over proliferation. We have employed RNA interference and dexamethasone to modulate connexin32 expression in MH(1)C(1) cells to a range of concentrations. This allowed the determination of the quantitative relationship between connexin32 protein expression and cell proliferation. The magnitude of cell proliferation, measured by bromodeoxyuridine incorporation, was inversely proportional to the level of connexin32 expression. Q-PCR indicated a lack of change of expression of a range of cell cycle-related genes at 24h. The inverse relationship between Cx32 expression and proliferation was continuous, and a threshold level of reduction of connexin32 was not observable for an influence on proliferation.

Cell adhesion dynamics and actin cytoskeleton reorganization in HepG2 cell aggregates.

The temporal dependence of cytoskeletal remodelling on cell-cell contact in HepG2 cells has been established here. Cell-cell contact occurred in an ultrasound standing wave trap designed to form and levitate a 2-D cell aggregate, allowing intercellular adhesive interactions to proceed, free from the influences of solid substrata. Membrane spreading at the point of contact and change in cell circularity reached 50% of their final values within 2.2 min of contact. Junctional F-actin increased at the interface but lagged behind membrane spreading, reaching 50% of its final value in 4.4 min. Aggregates had good mechanical stability after 15 min in the trap. The implication of this temporal dependence on the sequential progress of adhesion processes is discussed. These results provide insight into how biomimetic cell aggregates with some liver cell functions might be assembled in a systematic, controlled manner in a 3-D ultrasound trap.