Arthroplasty in the haemophiliac patient is associated with higher rates of infection and is traditionally performed in a younger age group. Despite this there is little evidence in the literature regarding revision arthroplasty in this cohort of patients. We describe the case of a periprosthetic fracture in a haemophiliac patient requiring revision arthroplasty, who did not consent to receiving blood products due to religious beliefs, with a successful outcome.
There is a long history of certain medical conditions being associated with stigma, stereotypes, and negative attitudes. Research has shown that such attitudes can have a detrimental effect on patients presenting with stigmatised medical conditions and can even flow on to impact their family. The objective of this study was to measure the attitudes of undergraduate students enrolled in six different health-related courses at Monash University toward patients with intellectual disability, substance abuse, and acute mental illness.
A convenience sample of undergraduate students enrolled in six health-related courses in first, second and third years at Monash University were surveyed. The Medical Condition Regard Scale - a valid and reliable, self-report measure of attitudes - was administered to students along with a brief demographic form. Mean scores, t-tests, and ANOVA were used to analyse student attitudes. Ethics approval was granted.
548 students participated. Statistically significant differences were found between the courses (p = 0.05), year of the course (p = 0.09), and gender (p = 0.04) for the medical condition of intellectual disability. There was no statistically significant difference between the courses, year of the course, gender, and age group for substance abuse or acute mental illness conditions.
The findings suggest that students in undergraduate health-related courses, as a group, have a strong regard for patients with intellectual disability and some regard for patients with acute mental illness, but not for patients presenting with substance abuse problems.
Lupus myocarditis is a life threatening complication of systemic lupus erythematosus (SLE). A case of left ventricular failure secondary to myocarditis occurring in a patient with SLE is reported. Despite resolution of the cardiac failure with pulsed cyclophosphamide and steroids, she eventually died of non-cardiac complications 18 months later. The literature is also reviewed.
Extremely preterm (EP) survivors have smaller brains, lower IQ, and worse educational achievement than their term-born peers. The contribution of smaller brain size to the IQ and educational disadvantages of EP is unknown. This study aimed (i) to compare brain volumes from multiple brain tissues and structures between EP-born (<28weeks) and term-born (≥37weeks) control adolescents, (ii) to explore the relationships of brain tissue volumes with IQ and basic educational skills and whether this differed by group, and (iii) to explore how much total brain tissue volume explains the underperformance of EP adolescents compared with controls.
Longitudinal cohort study of 148 EP and 132 term controls born in Victoria, Australia in 1991-92. At age 18, magnetic resonance imaging-determined brain volumes of multiple tissues and structures were calculated. IQ and educational skills were measured using the Wechsler Abbreviated Scale of Intelligence (WASI) and the Wide Range Achievement Test(WRAT-4), respectively.
Brain volumes were smaller in EP adolescents compared with controls (mean difference [95% confidence interval] of -5.9% [-8.0, -3.7%] for total brain tissue volume). The largest relative differences were noted in the thalamus and hippocampus. The EP group had lower IQs(-11.9 [-15.4, -8.5]), spelling(-8.0 [-11.5, -4.6]), math computation(-10.3 [-13.7, -6.9]) and word reading(-5.6 [-8.8, -2.4]) scores than controls; all p-values<0.001. Volumes of total brain tissue and other brain tissues and structures correlated positively with IQ and educational skills, a relationship that was similar for both the EP and controls. Total brain tissue volume explained between 20-40% of the IQ and educational outcome differences between EP and controls.
EP adolescents had smaller brain volumes, lower IQs and poorer educational performance than controls. Brain volumes of multiple tissues and structures are related to IQ and educational outcomes. Smaller total brain tissue volume is an important contributor to the cognitive and educational underperformance of adolescents born EP.
The incidence of hip replacements in the younger patient is ever increasing. With this in mind, improving the longevity of hip arthroplasties is paramount. Alumina ceramic is a promising bearing surface due to its low wear rate and biological inertness.
This study aims to review our experience with ceramic-on-ceramic total hip arthroplasty, reporting on the need for revision as well as the cause of failure. Our secondary purpose is to review our experience with the phenomenon of squeaking analysing and its effect on clinical outcome with specific emphasis on component positioning. Also reported are the results of our retrieval analysis of explanted components documenting the wear rate and our analysis of strip wear.
A consecutive series of 301 primary cementless alumina-on-alumina total hip arthroplasties at a minimum of 10 years follow-up was reviewed. These arthroplasties all had third-generation ceramic-on-ceramic bearings performed through a posterior approach with repair of capsule and external rotators to bone. We analysed hips both clinically and radiographically. Analysis of wear in 62 ceramic bearings was performed using a Roundtest RA300 machine (Mitutoyo; Andover, UK), which has an accuracy of 0.01 μm.
Overall, the survival rate of the implants was 98% at 10 years. No ceramic fractures were encountered in this study. Seventy-four patients reported squeaking hips, and two cases were revised due to squeaking (0.6%). No failures were related to bearing wear.
We believe that ceramic-on-ceramic is a safe bearing coupling with excellent survivorship at 10 years.
ceramic-on-ceramic; alumina; review; squeaking; alumina fracture
The mammalian gastrointestinal tract contains a large and diverse population of commensal bacteria and is also one of the primary sites of exposure to pathogens. How the immune system perceives commensals in the context of mucosal infection is unclear. Here we show that during a gastrointestinal infection, tolerance to commensals is lost and microbiota-specific T cells are activated and differentiate to inflammatory effector cells. Furthermore, these T cells go on to form memory cells that are phenotypically and functionally consistent with pathogen-specific T cells. Our results suggest that during a gastrointestinal infection, the immune response to commensals parallels the immune response against pathogenic microbes and that adaptive responses against commensals are an integral component of mucosal immunity.
Selected Reaction Monitoring (SRM) is a method of choice for accurate quantitation of low-abundance proteins in complex backgrounds. This strategy is, however, sensitive to interference from other components in the sample that have the same precursor and fragment masses as the monitored transitions. We present here an approach to detect interference by using the expected relative intensity of SRM transitions. We also designed an algorithm to automatically detect the linear range of calibration curves. These approaches were applied to the experimental data of Clinical Proteomic Tumor Analysis Consortium (CPTAC) Verification Work Group Study 7 and show that the corrected measurements provide more accurate quantitation than the uncorrected data.
The title compound, [Sn(C6H5)2Cl2(CH4N2S)2], has been obtained from the reaction between Sn(C6H5)2Cl2 and SC(NH2)2. The asymmetric unit consists of one half of the molecular unit, the remainder generated by a twofold rotation axis located along the Cl—Sn—Cl bonds. The SnIV atom is coordinated by two phenyl groups, two Cl atoms and two thiourea ligands in an all trans octahedral C2Cl2S2 environment. Individual molecules are connected through N—H⋯Cl hydrogen bonds, leading to a three-dimensional network structure. Intramolecular N—H⋯Cl hydrogen bonds are also present.
Mass spectrometry is a method of choice for quantifying low-abundance proteins and peptides in many biological studies. Here, we describe a range of computational aspects of protein and peptide quantitation, including methods for finding and integrating mass spectrometric peptide peaks, and detecting interference to obtain a robust measure of the amount of proteins present in samples.
Proteomics; Quantitation; Proteins; Peptides; Mass spectrometry
Intestinal commensal bacteria induce protective and regulatory responses that maintain host-microbial mutualism. However, the contribution of tissue-resident commensals to immunity and inflammation at other barrier sites has not been addressed. We found that in mice, the skin microbiota have an autonomous role in controlling the local inflammatory milieu and tuning resident T lymphocyte function. Protective immunity to a cutaneous pathogen was found to be critically dependent on the skin microbiota but not the gut microbiota. Furthermore, skin commensals tuned the function of local T cells in a manner dependent on signaling downstream of the interleukin-1 receptor. These findings underscore the importance of the microbiota as a distinctive feature of tissue compartmentalization, and provide insight into mechanisms of immune system regulation by resident commensal niches in health and disease.
Secretory leukoprotease inhibitor (SLPI) is an anti-inflammatory protein present in respiratory secretions. Whilst epithelial cell SLPI is extensively studied, neutrophil associated SLPI is poorly characterised. Neutrophil function including chemotaxis and degranulation of proteolytic enzymes involves changes in cytosolic calcium (Ca2+) levels which is mediated by production of inositol 1,4,5-triphosphate (IP3) in response to G-protein-coupled receptor (GPCR) stimuli. The aim of this study was to investigate the intracellular function of SLPI and the mechanism-based modulation of neutrophil function by this antiprotease. Neutrophils were isolated from healthy controls (n = 10), individuals with cystic fibrosis (CF) (n = 5) or chronic obstructive pulmonary disease (COPD) (n = 5). Recombinant human SLPI significantly inhibited fMet-Leu-Phe (fMLP) and interleukin(IL)-8 induced neutrophil chemotaxis (P < 0.05) and decreased degranulation of matrix metalloprotease-9 (MMP-9), hCAP-18, and myeloperoxidase (MPO) (P < 0.05). The mechanism of inhibition involved modulation of cytosolic IP3 production and downstream Ca2+ flux. The described attenuation of Ca2+ flux was overcome by inclusion of exogenous IP3 in electropermeabilized cells. Inhibition of IP3 generation and Ca2+ flux by SLPI may represent a novel anti-inflammatory mechanism, thus strengthening the attractiveness of SLPI as a potential therapeutic molecule in inflammatory airway disease associated with excessive neutrophil influx including CF, non-CF bronchiectasis, and COPD.
Dissemination of prevention-focused evidence-based programs (EBPs) from research to community settings may improve population health and reduce health disparities, but such flow has been limited. Academic–community partnerships using community-based participatory research (CBPR) principles may support increased dissemination of EBPs to community-based organizations (CBOs). This qualitative study examined the EBP-related perceptions and needs of CBOs targeting underserved populations. As part of PLANET MassCONECT, a CBPR study, we conducted six key informant interviews with community leaders and four focus groups with CBO staff members in Boston, Worcester and Lawrence, Massachusetts, in 2008. Working definitions of EBPs among CBO staff members varied greatly from typical definitions used by researchers or funders. Key barriers to using EBPs included: resource constraints, program adaptation challenges and conflicts with organizational culture. Important facilitators of EBP usage included: program supports for implementation and adaptation, collaborative technical assistance and perceived benefits of using established programs. This exploratory study highlights differences among key stakeholders regarding the role of evidence in program planning and delivery. An updated perspective should better incorporate CBO perspectives on evidence and place greater, and much needed, emphasis on the impact of context for EBP dissemination in community settings.
Tyrosine phosphorylation-dependent signaling, as mediated by members of the epidermal growth factor receptor (EGFR) family (ErbB1 to -4) of protein tyrosine kinases (PTKs), Src family PTKs (SFKs), and cytokines such as interleukin-6 (IL-6) that signal via signal transducer and activator of transcription 3 (STAT3), is critical to the development and progression of many human breast cancers. EGFR, SFKs, and STAT3 can serve as substrates for the protein tyrosine phosphatase TCPTP (PTPN2). Here we report that TCPTP protein levels are decreased in a subset of breast cancer cell lines in vitro and that TCPTP protein is absent in a large proportion of “triple-negative” primary human breast cancers. Homozygous TCPTP deficiency in murine mammary fat pads in vivo is associated with elevated SFK and STAT3 signaling, whereas TCPTP deficiency in human breast cancer cell lines enhances SFK and STAT3 signaling. On the other hand, TCPTP reconstitution in human breast cancer cell lines severely impaired cell proliferation and suppressed anchorage-independent growth in vitro and xenograft growth in vivo. These studies establish TCPTP's potential to serve as a tumor suppressor in human breast cancer.
The incidence of cancer is increasing worldwide, with the advent of a myriad of new treatment options, so is the overall survival of these patients. However, from an orthopaedic perspective, there comes the challenge of treating more patients with a variety of metastatic bone lesions. The consequences of such lesions can be significant to the patient, from pain and abnormal blood results, including hypercalcemia, to pathological fracture. Given the multiple options available, the treatment of bone metastasis should be based on a patient-by patient manner, as is the case with primary bone lesions. It is imperative, given the various lesion types and locations, treatment of bone metastasis should be performed in an individualised manner. We should consider the nature of the lesion, the effect of treatment on the patient and the overall outcome of our decisions. The dissemination of primary lesions to distant sites is a complex pathway involving numerous cytokines within the tumour itself and the surrounding microenvironment. To date, it is not fully understood and we still base a large section of our knowledge on Pagets historic “seed and soil” theory. As we gain further understanding of this pathway it will allow us develop more medical based treatments. The treatment of primary cancers has long been provided in a multi-disciplinary setting to achieve the best patient outcomes. This should also be true for the treatment of bone metastases. Orthopaedic surgeons should be involved in the multidisciplinary treatment of such patients given that there are a variety of both surgical fixation methods and non-operative methods at our disposal.
Bone metastases; Diagnosis; Pathophysiology; Surgical treatment, Medical treatment
Rituximab (R) is a chimeric human-murine anti-CD20 monoclonal antibody used to treat B-cell lymphomas. Despite R remarkable activity against malignant cells, there are concerns that R may facilitate the occurrence of infections. This study is aimed to define risk factors for infections, and the potential interaction with time since therapy, in patients undergoing R containing regimens.
The study has been designed as a multiple failure events historical cohort including all patients who received a R contain regimen at London Royal Free Hospital between May 2007 and April 2009.
One-hundred-eighty-one infections occurred among the 113 enrolled patients (overall incidence rate 3.30 per 1000 person-days). Multivariate analysis showed that lymphocyte counts at nadir, graft versus host disease, HIV sero-status and the type of malignancy were all independently associated with the risk of infection. In addition the analysis of the interaction with the time since the start of therapy provided evidence that different risk factors may increase risk of infections in different times.
This study provides preliminary data to describe the association between several patients’ baseline characteristics and infections during therapy with R.
There is growing evidence that antihypertensive agents, particularly centrally acting ACE inhibitors (CACE-Is), which cross the blood–brain barrier, are associated with a reduced rate of cognitive decline. Given this, we compared the rates of cognitive decline in clinic patients with dementia receiving CACE-Is (CACE-I) with those not currently treated with CACE-Is (NoCACE-I), and with those who started CACE-Is, during their first 6 months of treatment (NewCACE-I).
Observational case–control study.
2 university hospital memory clinics.
817 patients diagnosed with Alzheimer's disease, vascular or mixed dementia. Of these, 361 with valid cognitive scores were included for analysis, 85 CACE-I and 276 NoCACE-I.
Patients were included if the baseline and end-point (standardised at 6 months apart) Standardised Mini-Mental State Examination (SMMSE) or Quick Mild Cognitive Impairment (Qmci) scores were available. Patients with comorbid depression or other dementia subtypes were excluded. The average 6-month rates of change in scores were compared between CACE-I, NoCACE-I and NewCACE-I patients.
When the rate of decline was compared between groups, there was a significant difference in the median, 6-month rate of decline in Qmci scores between CACE-I (1.8 points) and NoCACE-I (2.1 points) patients (p=0.049), with similar, non-significant changes in SMMSE. Median SMMSE scores improved by 1.2 points in the first 6 months of CACE treatment (NewCACE-I), compared to a 0.8 point decline for the CACE-I (p=0.003) group and a 1 point decline for the NoCACE-I (p=0.001) group over the same period. Multivariate analysis, controlling for baseline characteristics, showed significant differences in the rates of decline, in SMMSE, between the three groups, p=0.002.
Cognitive scores may improve in the first 6 months after CACE-I treatment and use of CACE-Is is associated with a reduced rate of cognitive decline in patients with dementia.
The African malaria mosquito Anopheles gambiae is polymorphic for chromosomal inversion 2La, whose frequency strongly correlates with degree of aridity across environmental gradients. Recent physiological studies have associated 2La with resistance to desiccation in adults and thermal stress in larvae, consistent with its proposed role in aridity tolerance. However, the genetic basis of these traits remains unknown. To identify genes that could be involved in the differential response to thermal stress, we compared global gene expression profiles of heat hardened 2La or 2L+a larvae at three time points, for up to eight hours following exposure to the heat stress. Treatment and control time series, replicated four times, revealed a common and massive induction of a core set of heat shock genes regardless of 2La orientation. However, clear differences between the 2La and 2L+a arrangements emerged at the earliest (0.25 h) time point, in the intensity and nature of the stress response. Overall, 2La was associated with the more aggressive response: larger numbers of genes were heat responsive and up-regulated. Transcriptionally induced genes were enriched for functions related to ubiquitin-proteasomal degradation, chaperoning, and energy metabolism. The more muted transcriptional response of 2L+a was largely repressive, including genes involved in proteolysis and energy metabolism. These results may help explain the maintenance of the 2La inversion polymorphism in An. gambiae, as the survival benefits offered by high thermal sensitivity in harsh climates could be offset by the metabolic costs of such a drastic response in more equable climates.
Anopheles gambiae; chromosomal inversion; heat hardening; malaria vector; microarray; thermal stress; transcriptional profiling
Previous work demonstrates that early life stress (ELS) and HPA-axis function predict later psychopathology. Animal work and cross-sectional human studies suggest that this process might operate through amygdala-ventromedial prefrontal cortical (vmPFC) circuitry implicated in emotion regulation. The current study prospectively investigated the roles of ELS and childhood basal cortisol in the development of adolescent resting-state functional connectivity (fcMRI) in the amygdala-PFC circuit. In females only, greater ELS predicted increased childhood cortisol levels, which, in turn, predicted decreased amygdala-vmPFC fcMRI 14 years later. Further, for females, amygdala-vmPFC fcMRI was inversely correlated with concurrent anxious symptoms, but positively associated with depressive symptoms, suggesting differing pathways from childhood cortisol function through adolescent amygdala-vmPFC functional connectivity to anxiety and depression. These data highlight that, for females, the effects of ELS and early HPA-axis function may be detected much later in the intrinsic processing of emotion-related brain circuits.
Hurling is Ireland's national sport, played with a stick and ball; injury to the hand is common. A decrease in the proportion of head injury among emergency department (ED) presentations for hurling-related injury has coincided with voluntary use of helmet and face protection since 2003. A similar decrease in proportions has not occurred in hand injury. We aim to quantify hurling-related ED presentations and examine variables associated with injury. In particular, we were interested in comparing the occurrence of hand injury in those using head and face protection versus those who did not.
This study utilised a retrospective cross-sectional study design.
This study took place at a university hospital ED over a 3-month period.
A follow-up telephone interview was performed with 163 players aged ≥16 years to reflect voluntary versus obligatory helmet use.
The hand was most often injured (n=85, 52.1%). Hand injury most commonly occurred from a blow of a hurley (n=104, 65%), and fracture was confirmed in 62% of cases. Two-thirds of players (66.3%) had multiple previous (1–5) hand injuries. Most patients 149 (91.4%) had tried commercially available hand protection, but only 4.9% used hand protection regularly. Univariate analysis showed a statistically significant association between wearing a helmet and faceguard and hand injury; OR 2.76 (95% CI 1.42 to 5.37) p=0.003. On further analysis adjusting simultaneously for age, prior injury, foul play and being struck by a hurley, this relationship remained significant (OR 3.15 95% CI 1.51 to 6.56, p=0.002).
We report that hurling-related hand injury is common. We noted the low uptake of hand protection. We found that hand injury was significantly associated with the use of helmet and faceguard protection, independent of the other factors studied. Further studies are warranted to develop strategies to minimise the occurrence of this injury.
Introduction: the Qmci is a sensitive and specific test to differentiate between normal cognition (NC), mild cognitive impairment (MCI) and dementia. We compared the sensitivity and specificity of the subtests of the Qmci to determine which best discriminated NC, MCI and dementia.
Objective: the objective was to determine the contribution each subtest of the Qmci makes, to its sensitivity and specificity in differentiating MCI from NC and dementia, to refine and shorten the instrument.
Methods: existing data from our previous study of 965 subjects, testing the Qmci, was analysed to compare the sensitivity and specificity of the Qmci subtests.
Results: all the subtests of the Qmci differentiated MCI from NC. Logical memory (LM) performed the best (area under the receiver operating curve of 0.80), registration the worst, (0.56). LM and verbal fluency had the largest median differences (expressed as percentage of total score) between MCI and NC, 20 and 25%, respectively. Other subtests did not have clinically useful differences. LM was best at differentiating MCI from NC, irrespective of age or educational status.
Conclusion: the Qmci incorporates several important cognitive domains making it useful across the spectrum of cognitive impairment. LM is the best performing subtest for differentiating MCI from NC.
Quick mild cognitive impairment screen; mild cognitive impairment; standardised Mini-Mental State Examination; sensitivity and specificity; cognitive domains
Genomic studies of human disease and drug response aim to find one or a few causal variants among millions of possible candidates. A streamlined platform for quickly and reliably assessing each variant called in such studies can save months of tedious effort, speeding discoveries for core labs' clinical and research clients, and freeing core staff to solve other data analysis challenges posed by broader clientele. Made to help cores and their clients quickly interpret human genomes, the Ingenuity® Variant Analysis™ platform (www.ingenuity.com/variants) lets users upload, annotate, and thoroughly compare whole or partial human genomes, to smartly shortlist candidate variants, genes, and pathways that may best explain user-specified phenotype(s). Leveraging Ingenuity's deep, structured knowledge base of published findings and robust predictive insight, Variant Analysis runs sophisticated tests of family- and population-scale genetic association, tailored to the user's study design and phenotype, via a simple, fluid interface that also lets one easily review, revise, and share findings. To meet the distinctive challenges of clinical genome interpretation, we have comprehensively curated published clinical assessments and population incidence of individual human sequence variants, supplementing gene- and pathway-level functional knowledge. To help researchers identify new causal candidates, we have built and validated Variant Analysis to run gene- and pathway-level burden tests ∼100x faster than conventional methods. And, by letting users easily and securely share genome data and findings with collaborators, the platform mediates efficient collaborative discovery among researchers studying similar or (as mutual controls) distinct rare diseases. Combining sophisticated functional analytics; statistically robust genetic analysis at the variant, gene, and pathway levels in an intuitive interface, the Variant Analysis platform is built to meet the varied genome interpretation needs of researchers and clinicians studying single and multiple probands, pedigrees, and case-control cohorts, to understand rare inborn diseases, common complex disease, cancers, and drug response.
Prior to the introduction of tamoxifen, high dose estradiol was used to treat breast cancer patients with similar efficacy as tamoxifen, albeit with some undesirable side effects. There is renewed interest to utilize estradiol to treat endocrine resistant breast cancers, especially since findings from several preclinical models and clinical trials indicate that estradiol may be a rational second-line therapy in patients exhibiting resistance to tamoxifen and/or aromatase inhibitors. We and others reported that breast cancer patients bearing protein kinase C alpha (PKCα)- expressing tumors exhibit endocrine resistance and tumor aggressiveness. Our T47D:A18/PKCα preclinical model is tamoxifen-resistant, hormone-independent, yet is inhibited by 17β-estradiol (E2) in vivo. We previously reported that E2-induced T47D:A18/PKCα tumor regression requires extranuclear ERα and interaction with the extracellular matrix.
T47D:A18/PKCα cells were grown in vitro using two-dimensional (2D) cell culture, three-dimensional (3D) Matrigel and in vivo by establishing xenografts in athymic mice. Immunofluoresence confocal microscopy and co-localization were applied to determine estrogen receptor alpha (ERα) subcellular localization. Co-immunoprecipitation and western blot were used to examine interaction of ERα with caveolin-1.
We report that although T47D:A18/PKCα cells are cross-resistant to raloxifene in cell culture and in Matrigel, raloxifene induces regression of tamoxifen-resistant tumors. ERα rapidly translocates to extranuclear sites during T47D:A18/PKCα tumor regression in response to both raloxifene and E2, whereas ERα is primarily localized in the nucleus in proliferating tumors. E2 treatment induced complete tumor regression whereas cessation of raloxifene treatment resulted in tumor regrowth accompanied by re-localization of ERα to the nucleus. T47D:A18/neo tumors that do not overexpress PKCα maintain ERα in the nucleus during tamoxifen-mediated regression. An association between ERα and caveolin-1 increases in tumors regressing in response to E2.
Extranuclear ERα plays a role in the regression of PKCα-overexpressing tamoxifen-resistant tumors. These studies underline the unique role of extranuclear ERα in E2- and raloxifene-induced tumor regression that may have implications for treatment of endocrine-resistant PKCα-expressing tumors encountered in the clinic.
Breast cancer; PKCα; Extranuclear ERα; Tamoxifen; Raloxifene
M2 muscarinic acetylcholine receptors modulate cardiac rhythm via regulation of the inward potassium current. To increase our understanding of M2 receptor physiology we used Total Internal Reflection Fluorescence Microscopy to visualize individual receptors at the plasma membrane of transformed CHOM2 cells, a cardiac cell line (HL-1), primary cardiomyocytes and tissue slices from pre- and post-natal mice. Receptor expression levels between individual cells in dissociated cardiomyocytes and heart slices were highly variable and only 10% of murine cardiomyocytes expressed muscarinic receptors. M2 receptors were evenly distributed across individual cells and their density in freshly isolated embryonic cardiomyocytes was ~ 1 μm− 2, increasing at birth (to ~ 3 μm− 2) and decreasing back to ~ 1 μm− 2 after birth. M2 receptors were primarily monomeric but formed reversible dimers. They diffused freely at the plasma membrane, moving approximately 4-times faster in heart slices than in cultured cardiomyocytes. Knowledge of receptor density and mobility has allowed receptor collision rate to be modeled by Monte Carlo simulations. Our estimated encounter rate of 5–10 collisions per second, may explain the latency between acetylcholine application and GIRK channel opening.
Individual M2 muscarinic receptors were visualized and tracked in live cardiac tissue slices to establish their abundance, distribution, mobility and oligomeric state in situ.
► The first observation of single molecules moving on the surface of living tissue ► Only ca. 10% of murine cardiomyocytes expressed M2 receptors at appreciable levels. ► M2 density at birth was 3-fold higher than that in embryonic and adult myocytes. ► M2 receptors were primarily monomeric but formed reversible dimers. ► M2 receptors diffused 4-times faster in heart slices than in cultured myocytes.
Single molecule; TIRF; Acetylcholine receptor; Muscarinic; Cardiomyocyte
Arteriopathy is an uncommon complication of primary varicella zoster virus (VZV) infection in the immunocompetent adult. We report a case of a 39-year-old woman known to be VZV negative prior to the event. She presented to the emergency department having experienced an episode of expressive aphasia and right upper limb paraesthesia lasting 15 min. The symptoms followed a 3-day period of general malaise, arthralgia and a generalised maculopapular itchy rash involving face and limbs. No immunocompromise was detected but an infectious contact was identified in the home. Imaging findings were consistent with a focal cerebritis/vasculopathy and VZV infection was confirmed with cerebrospinal fluid PCR analysis. Resolution of radiological signs occurred following prompt treatment with appropriate antivirals.