Multidimensional biomarker predicts disease control in response to immunotherapy in recurrent or metastatic head and neck squamous-cell carcinoma

PURPOSE

Anti-PD-1 therapy provides clinical benefit in 40-50% of patients with relapsed and/or metastatic head and neck squamous cell carcinoma (RM-HNSCC). Selection of anti- PD-1 therapy is typically based on patient PD-L1 immunohistochemistry (IHC) which has low specificity for predicting disease control. Therefore, there is a critical need for a clinical biomarker that will predict clinical benefit to anti-PD-1 treatment with high specificity.

METHODS

Clinical treatment and outcomes data for 103 RM-HNSCC patients were paired with RNA-sequencing data from formalin-fixed patient samples. Using logistic regression methods, we developed a novel biomarker classifier based on expression patterns in the tumor immune microenvironment to predict disease control with monotherapy PD-1 inhibitors (pembrolizumab and nivolumab). The performance of the biomarker was internally validated using out-of-bag methods.

RESULTS

The biomarker significantly predicted disease control (65% in predicted non-progressors vs. 17% in predicted progressors, p < 0.001) and was significantly correlated with overall survival (OS; p = 0.004). In addition, the biomarker outperformed PD-L1 IHC across numerous metrics including sensitivity (0.79 vs 0.64, respectively; p = 0.005) and specificity (0.70 vs 0.61, respectively; p = 0.009).

CONCLUSION

This novel assay uses tumor immune microenvironment expression data to predict disease control and OS with high sensitivity and specificity in patients with RM-HNSCC treated with anti-PD-1 monotherapy.

Arthroscopic Simulation in Orthopaedic Surgery Training

Surgical simulation has become a commonly utilized and well-researched training adjunct in nearly all surgical specialties. Balancing high-quality orthopaedic surgical training in the face of work hour restrictions and efficiency pressures has become a challenge to educators and trainees alike. Surgical simulation is an opportunity to enhance such training and potentially permit trainees to be better equipped for the operating room. In orthopaedics, various low-fidelity, high-fidelity, and virtual reality simulation platforms are readily available to almost all trainees and permit simulation of a wide array of arthroscopic surgeries. In this review, we seek to highlight the potential utility of simulation-based training in orthopaedic surgery, the various types of available simulators, and review the evidence for simulator use.

Non-Full House Membranous Lupus Nephritis Represents a Clinically Distinct Subset

Key Points

Non-full house (NFH) membranous lupus nephritis (MLN) is a minor subset of all MLN cases. Patients with NFH MLN tend to be older when diagnosed with systemic lupus erythematosus, undergo first renal biopsy at an older age, and have fewer extrarenal systemic manifestations. Lower load of C3 glomerular deposits seen in NFH MLN biopsies suggests attenuation of complement-mediated injury, which may have wider systemic implications.

Background

Renal involvement in systemic lupus erythematosus (SLE) is a key predictor of morbidity and mortality. Immunofluorescence (IF) staining of glomeruli is typically positive for IgG, IgA, IgM, C3, and C1q—the full house (FH) pattern. However, a subset of patients with membranous lupus nephritis (MLN) have a Non-FH (NFH) IF pattern more typical of idiopathic membranous nephropathy.

Methods

From a multi-institutional cohort of 113 MLN cases, we identified 29 NFH MLN biopsies. NFH MLN was defined by IF criteria: ≥1+ glomerular capillary loop IgG staining and<1+ IgA, IgM, and C1q. FH MLN was defined as ≥1+ staining for all five antibodies. Intermediate (Int) cases did not meet criteria for FH or NFH. We compared the pathological and clinical characteristics and outcomes among patients with FH, NFH, and Int IF patterns on kidney biopsy.

Results

NFH MLN represents a subset of MLN biopsies (13.4%). Compared with patients with FH MLN, patients with NFH MLN were older at SLE diagnosis (29 versus 22.5 years), had a longer time to initial kidney biopsy (8 versus 3.16 years), and had fewer SLE manifestations (2.5 versus 3.36 involved systems). NFH MLN biopsies showed lower C3 IF intensity (1.16+ versus 2.38+). Int biopsies had findings intermediate between those of NFH and FH groups.

Conclusions

NFH IF pattern defines a small subset of MLN biopsies and appears to be associated with milder clinical manifestations and slower disease progression. Less robust C3 deposition in NFH MLN may suggest a pathophysiology distinct from that of FH MLN.

Genome-wide gene expression responses to experimental manipulation of Saccharomyces cerevisiae repressor activator protein 1 (Rap1) expression level

Precise regulation of transcription in gene expression is critical for all aspects of normal organism form, fitness, and function and even minor alterations in the level, location, and timing of gene expression can result in phenotypic variation within and between species including evolutionary innovations and human disease states. Eukaryotic transcription is regulated by a complex interplay of multiple factors working both at a physical and molecular levels influencing this process. In Saccharomyces cerevisiae, the TF with the greatest number of putative regulatory targets is the essential gene Repressor Activator Protein 1 (RAP1). While much is known about the roles of Rap1 in gene regulation and numerous cellular processes, the response of Rap1 target genes to systematic titration of RAP1 expression level remains unknown. To fill this knowledge gap, we used a strain with a tetracycline-titratable promoter replacing wild-type regulatory sequences of RAP1 to systematically reduce the expression level of RAP1 and followed this with RNA sequencing (RNA-seq) to measure genome-wide gene expression responses. Previous research indicated that Rap1 plays a significant regulatory role in particular groups of genes including telomere-proximal genes, homothallic mating (HM) loci, glycolytic genes, DNA repair genes, and ribosomal protein genes; therefore, we focused our analyses on these groups and downstream targets to determine how they respond to reductions in RAP1 expression level. Overall, despite being known as both an activator and as a repressor of its target genes, we found that Rap1 acts as an activator for more target genes than as a repressor. Additionally, we found that Rap1 functions as an activator of ribosomal protein genes and a repressor of the silent mating locus genes consistent with predictions from the literature. Unexpectedly, we found that Rap1 functions as a repressor of glycolytic enzyme genes contrary to prior reports of it having the opposite effect. We also compared the expression of RAP1 to five different genes related to DNA repair pathway and found that decreasing RAP1 downregulated four of those five genes. Finally, we found no effect of RAP1 depletion on telomere-proximal genes despite its functioning to silence telomeric repeat-containing RNAs. Together our results enrich our understanding of this important transcriptional regulator. The graphical abstract is provided as a supplementary fig. (S-Fig 1).

Tranexamic Acid Utilization in Foot and Ankle Surgery: A Meta-analysis

BACKGROUND

Tranexamic acid (TXA) has been widely used in various orthopaedic subspecialities to decrease blood loss, transfusions, and wound complications. However, the role of TXA in foot and ankle surgery is not clearly delineated. This meta-analysis aims to report the efficacy and safety of TXA in relation to foot and ankle surgical procedures.

METHODS

Database searches were conducted for eligible studies from data inception through January 2022. Clinical studies on the use of TXA in foot and ankle procedures reporting the desired outcomes were included. Outcomes were estimated blood loss, change in hemoglobin, and overall complications. Risk of bias was assessed using the Newcastle-Ottawa quality assessment scale and the Joanna Briggs Institute (JBI) critical appraisal tool.

RESULTS

Nine studies met the inclusion criteria. A total of 752 foot and ankle procedures were included, in which 511 (67.95%) procedures received TXA whereas 241 (32.05%) served as controls and did not receive TXA. The pooled data of change in hemoglobin and overall complications showed no difference between the TXA and control group. Estimated blood loss was significantly lower in the patients who received TXA.

CONCLUSION

In conclusion, TXA use was associated with lower estimated blood loss in foot and ankle surgeries without increased risk of thromboembolic events, wound complications, or changes in hemoglobin.

LEVEL OF EVIDENCE

Level IV, meta-analysis.

Supination Adduction Vertical Medial Malleolar Fracture Fixation with Buttress Plating vs a Novel Screw-Only Construct: A Cadaveric Biomechanical Study

BACKGROUND

Supination adduction ankle fractures are unique among rotational ankle fractures as plate constructs are more commonly used than independent screws for medial malleolar fixation. The purpose of this study was to compare fracture displacement between plate fixation to a novel screw-only construct using a cadaveric biomechanical early-weightbearing model for the treatment of vertical medial malleolus fractures.

METHODS

Six nonosteoporotic fresh-frozen cadaver shanks and feet in matched pairs underwent a vertical osteotomy of the medial malleolus to simulate the supination adduction type injury. Osteoporosis was measured using DEXA scans. One specimen from each pair was fixed with a one-third tubular buttress plate and the other with screw-only fixation. The specimens were then axially loaded for 100 000 cycles to simulate protected weightbearing, and subsequently loaded to failure in supination. Stiffness, fracture displacement, and load to failure were recorded. Statistical significance was set at P <.05.

RESULTS

There were no measurable differences in displacement between the 2 constructs during axial cyclic loading after 100 000 cycles (plate, 0.74 ± 0.09 mm; screws, 0.79 ± 0.18 mm; P = .225). During supination and axial load to failure, the plate outperformed the screw construct. For load to failure (2 mm displacement) at the fracture site, the plate group failed at 716 ± 240 N, whereas the screw group failed at 567 ± 237 N (P = .015). During load to catastrophic failure, the plate group outperformed the screw group (plate, 6011 ± 1646 N; screws, 4578 ± 1837 N; P = .002).

CONCLUSION

For vertical medial malleolar fractures, the screw-only construct demonstrated no statistical difference when compared to buttress plating for cyclical axial loading, simulating early weightbearing in a boot. However, buttress plating is 21% to 24% stronger than the screw-only fixation construct in overall strength and prevention of catastrophic failure when loading in a supinated position.

CLINICAL RELEVANCE

The screw-only construct is biomechanically similar to a buttress plate when simulating early protected weightbearing. This suggests that early weightbearing as tolerated in a controlled ankle motion boot beginning 2 weeks postoperatively is mechanically safe for this fracture pattern and does not result in unacceptable amounts of fracture displacement. This construct may be useful as a less invasive treatment modality for the treatment of vertical medial malleolus fractures in select patients.

Risk of chronic kidney disease in people living with HIV by tenofovir disoproxil fumarate (TDF) use and baseline D:A:D chronic kidney disease risk score

OBJECTIVES

To assess the risk of chronic kidney disease (CKD) associated with tenofovir disoproxil fumarate (TDF) use by baseline D:A:D CKD risk score.

METHODS

Adult antiretroviral therapy (ART)-naïve people living with HIV (PLWH) initiating treatment, with estimated glomerular filtration rate (eGFR) ≥ 60 mL/min/1.73 m2 , were identified in the OPERA cohort. CKD was defined as two or more consecutive eGFR < 60 mL/min/1.73 m2 , > 90 days apart. Associations between TDF use, baseline D:A:D CKD risk and incident CKD were assessed with incidence rates (IRs; Poisson regression) and adjusted pooled logistic regression. The impact of pharmacoenhancers on the observed association between TDF and CKD was also evaluated.

RESULTS

Of 9802 PLWH included, 6222 initiated TDF and 3580 did not (76% and 79% low D:A:D CKD risk, respectively). Overall, 125 CKD events occurred over 24 382 person-years of follow-up. Within strata of D:A:D CKD risk score, IRs were similar across TDF exposure, with high baseline CKD risk associated with highest incidence. Compared with the low-risk group without TDF, there was no statistical difference in odds of incident CKD in the low-risk group with TDF (adjusted odds ratio = 0.55, 95% confidence interval: 0.19-1.54). Odds of incident CKD did not differ statistically significantly by pharmacoenhancer exposure, with or without TDF.

CONCLUSIONS

In this large cohort of ART-naïve PLWH, incident CKD following ART initiation was infrequent and strongly associated with baseline CKD risk. TDF-containing regimens did not increase the odds of CKD in those with a low baseline D:A:D CKD risk, the largest group of ART-naïve PLWH, and may remain a viable treatment option in appropriate settings.

Examination of ionoregulatory characteristics of South American cichlids

We examined ionoregulatory traits of four cichlid species from South America, oscars (Astronotus ocellatus), Tapajos cichlids (Geophagus sp.), Macmaster's dwarf cichlids (Apistogramma macmasteri), and keyhole cichlids (Cleithracara maronii), all inhabitants of ion-poor waters. K_m values for Na⁺ transport in fish held in 100 μmol L^-1 Na⁺ water ranged from 49 to 143 μmol L^-1, and J_max values spanned 450 to 1205 nmol g^-1 h^-1. After one month in 1000 μmol L^-1 Na⁺ water, kinetic parameters for Na⁺ uptake in three of the four species acclimated, but only oscars displayed the "typical" pattern of higher K_m and lower J_max values. Low pH water inhibited Na⁺ uptake (J_in^Na) in all, and stimulated Na⁺ efflux (J_out^Na) 2.5 to 3.5-fold in three of the four species. Oscars alone had had a measurable J_in^Na at pH 3.5 and no stimulation of J_out^Na. We measured J_in^Na in oscars and keyhole cichlids during exposure to 100 μmol L^-1 Ethoxzolemide (EZ), an inhibitor of carbonic anhydrase, and 1 mmol L^-1 NH₄Cl (HEA). EZ inhibited J_in^Na by about 50% and HEA reduced J_in^Na by 80-90%. These results suggest that Na⁺ uptake involves H⁺ extrusion. Acute exposure to 1 μmol L^-1 CuSO₄ and 60 nmol L^-1 AgNO₃ inhibited J_in^Na in both species by 30-85%. Exposure of oscars to 5-fold higher concentrations of both metals did not further inhibit J_in^Na, but it did stimulate J_out^Na 50-150%. The response to metals of both species are similar to other species that have been examined.

Validation of the Data Collection on Adverse Events of Anti-HIV Drugs (D:A:D) chronic kidney disease risk score in HIV-infected patients in the USA

Objectives

The aim of the study was to assess the validity of an easy‐to‐calculate chronic kidney disease (CKD) risk score developed by the Data Collection on Adverse Events of Anti‐HIV Drugs (D:A:D) group in a longitudinal observational study of people living with HIV (PLWH) in the USA.

Methods

PLWH (2002–2016) without prior exposure to potentially nephrotoxic antiretroviral agents and with at least three estimated glomerular filtration rate (eGFR) test results were identified in the Observational Pharmaco‐Epidemiology Research and Analysis (OPERA^®) cohort. Three samples were drawn independently using the same eligibility criteria but each using a different eGFR equation, specifically the Cockcroft–Gault (C‐G), Modification of Diet in Renal Disease (MDRD) or Chronic Kidney Disease Epidemiology Collaboration (CKD‐EPI) eGFR estimation method. Full and short D:A:D risk scores were applied. CKD was defined as a confirmed decrease in eGFR to < 60 mL/min/1.73 m² (stages 3–5). Poisson models estimated the association between CKD incidence and a one‐point increase in the continuous risk score. The incidence rate ratio (IRR), adjusted IRR (aIRR), and Harrell's discrimination statistic were used to assess validity.

Results

There were 19 444, 22 727 and 22 748 PLWH in the OPERA C‐G, CKD‐EPI and MDRD samples, respectively. The median (minimum–maximum) follow‐up duration was 6.1 (0.3–9.1) years in the D:A:D cohort and ranged from 3.2 to 3.5 (0.2–15.5) years in the OPERA validation samples. The observation time for the majority of PLWH in the D:A:D cohort began prior to 2006, in stark contrast to the OPERA validation samples, where the majority of PLWH were observed after 2011. The CKD incidence ranged from 7.3 per 1000 person‐years [95% confidence interval (CI) 6.8, 7.9 per 1000 person‐years] in OPERA C‐G to 11.0 (95% CI 10.4, 11.6 per 1000 person‐years) in OPERA MDRD. In OPERA samples, IRRs by risk group and adjusted IRRs (full risk score) were similar to those in the D:A:D derivation cohort (adjusted IRR 1.3; 95% CI 1.3, 1.3). Harrell's c‐statistic ranged from 0.87 to 0.92 in the OPERA samples, comparable to that in the derivation cohort (0.92). Results for short scores were similar.

Conclusions

The findings support the validity of the D:A:D risk scoring method for assessing CKD (stages 3–5) probability in an exclusively USA‐based sample regardless of eGFR method.

County-level air quality and the prevalence of diagnosed chronic kidney disease in the US Medicare population

BACKGROUND

Considerable geographic variation exists in the prevalence of chronic kidney disease across the United States. While some of this variability can be explained by differences in patient-level risk factors, substantial variability still exists. We hypothesize this may be due to understudied environmental exposures such as air pollution.

METHODS

Using data on 1.1 million persons from the 2010 5% Medicare sample and Environmental Protection Agency air-quality measures, we examined the association between county-level particulate matter ≤2.5 μm (PM2.5) and the prevalence of diagnosed CKD, based on claims. Modified Poisson regression was used to estimate associations (prevalence ratios [PR]) between county PM2.5 concentration and individual-level diagnosis of CKD, adjusting for age, sex, race/ethnicity, hypertension, diabetes, and urban/rural status.

RESULTS

Prevalence of diagnosed CKD ranged from 0% to 60% by county (median = 16%). As a continuous variable, PM2.5 concentration shows adjusted PR of diagnosed CKD = 1.03 (95% CI: 1.02-1.05; p<0.001) for an increase of 4 μg/m3 in PM2.5. Investigation by quartiles shows an elevated prevalence of diagnosed CKD for mean PM2.5 levels ≥14 μg/m3 (highest quartile: PR = 1.05, 95% CI: 1.03-1.07), which is consistent with current ambient air quality standard of 12 μg/m3, but much lower than the level typically considered healthy for sensitive groups (~40 μg/m3).

CONCLUSION

A positive association was observed between county-level PM2.5 concentration and diagnosed CKD. The reliance on CKD diagnostic codes likely identified associations with the most severe CKD cases. These results can be strengthened by exploring laboratory-based diagnosis of CKD, individual measures of exposure to multiple pollutants, and more control of confounding.

Meta-analysis of the prevalence of renal cancer detected by abdominal ultrasonography

BACKGROUND

The potential for an ultrasound-based screening programme for renal cell carcinoma (RCC) to improve survival through early detection has been the subject of much debate. The prevalence of ultrasound-detected asymptomatic RCC is an important first step to establishing whether a screening programme may be feasible.

METHODS

A systematic search of MEDLINE and Embase was performed up to March 2016 to identify studies reporting the prevalence of renal masses and RCC. Two populations of patients were chosen: asymptomatic individuals undergoing screening ultrasonography and patients undergoing ultrasonography for abdominal symptoms not related to RCC. A random-effects meta-analysis was performed. Study quality was evaluated using a validated eight-point checklist.

RESULTS

Sixteen studies (413 551 patients) were included in the final analysis. The pooled prevalence of renal mass was 0·36 (95 per cent c.i. 0·23 to 0·52) per cent and the prevalence of histologically proven RCC was 0·10 (0·06 to 0·15) per cent. The prevalence of RCC was more than double in studies from Europe and North America than in those from Asia: 0·17 (0·09 to 0·27) versus 0·06 (0·03 to 0·09) per cent respectively. Data on 205 screen-detected RCCs showed that 84·4 per cent of tumours were stage T1-T2 N0, 13·7 per cent were T3-T4 N0, and only 2·0 per cent had positive nodes or metastases at diagnosis.

CONCLUSION

At least one RCC would be detected per 1000 individuals screened. The majority of tumours identified are early stage (T1-T2).

Rheology and structure of surface crosslinked surfactant-activated microgels

Nonionic surfactant-activated microgels (SAMs), composed of hydrophobic alkyl acrylates and hydrophilic hydroxyalkyl esters that utilize the effects of surfactant mediated swelling and interaction to provide pH-independent rheological properties, were previously reported as a new pathway to the rheology modification of surfactant solutions. Crosslinking was shown to play an important role in the properties of these soft microgel systems. To understand the impact of crosslinking chemistry on SAM polymers, we have compared two types of SAM polymers: a conventionally crosslinked SAM polymer via allyl pentaerythritol and a novel SAM polymer, where the surface is self-crosslinked via a reactive surfactant. We have systematically characterized the polymer's swelling, rheology and microstructure in a model system containing the polymer, sodium dodecyl sulfate (SDS) and water. Surface self-crosslinking is demonstrated to be a more effective crosslinking approach to create surfactant-mediated interactions between the microgel particles, resulting in more effective rheology modification. Internal crosslinking hinders both the full swelling of the SAM polymer as well as inter-particle bridging interactions, and is therefore less effective. To our best knowledge, this is the first report on creating a novel surface self-crosslinked microgel via a dual-functional reactive surfactant that interacts with a non-reactive surfactant to create a yield stress fluid.

Surfactant-activated microgels: a new pathway to rheology modification

Alkali swellable microgels are widely used to control rheology of formulated products containing surfactants. However, formulations based on these pH-responsive polymers show undesirably large changes in yield stress in a range of pH close to the pKa of the acid group. Analysis of the behavior of a cross-linked copolymer of ethyl acrylate and methacrylic acid in the nonionized form (at pH below the pKa of methacrylic acid) in the presence of sodium dodecyl sulfate shows surfactant-mediated swelling (an increase in particle diameter by over 2.5×) and a peak in zero-shear viscosity versus surfactant concentration indicating surfactant-mediated interaction of the swollen microgels. On the basis of these results, we demonstrate a new class of nonionic microgels composed of hydrophobic alkyl acrylates and hydrophilic hydroxyalkyl esters that utilize the effects of surfactant-mediated swelling and interaction to provide pH-independent rheological properties.

Abstract P6-05-28: Nicastrin RNA in situ hybridization (RNAScope®) reveals estrogen receptor negative breast cancer patients at risk of metastatic relapse and could serve as companion diagnostic for anti-nicastrin monoclonal antibody therapy

Introduction of targeted therapies into oncology requires co development of a drug and its companion diagnostic to achieve clinical efficacy and minimise side effects. Given the aggressive nature of estrogen receptor alpha negative (ERa-ve) breast cancer (BrCa), novel therapeutics are needed. Gamma-secretase enzyme is a relevant target in cancer, and within it, Nicastrin (NCSTN) is amenable to therapeutic intervention using monoclonal antibodies (mAb). NCSTN gene is amplified in a some breast tumours, which correlates with high NCSTN mRNA and adversely impacts overall survival (TCGA, Nature 2012). Immunohistochemistry revealed NCSTN protein overexpression in 47.5% of BrCa (n = 1000), conferring worse prognosis in the ERα-ve cohort. NCSTN genetic depletion in triple negative BrCa cells attenuated tumor growth in vitro and in vivo, invasive capacity, mesenchymal features and cancer stem-cell propagation (Filipovic et al; Lombardo et al). We have developed and characterized anti-NCSTN mAbs in terms of their therapeutic properties, functional effects in vitro and in vivo, and binding epitopes. Here, we have used a novel, bright-field chromogenic in situ hybridization technique (RNAscope), to quantify single-cell NCSTN mRNA levels in ERα-ve BrCa patients (n = 311), and propose this test as a companion diagnostic for targeted anti-NCSTN therapy. Methods:Paraffin BrCa tissue microarrays sections (Nottingham Tenovus ERα-ve cohort; n = 311) were analyzed by RNAScope using a NCSTN-specific probe (GenBank accession number NM_015331.2, and probe region: nt 158-1306). Visualized as brown punctate dots, RNA staining in individual tumor cells was scored semi-quantitatively on a 1-4 scale: 1 = 0-5 dots/cell, 2 = 6-10 dots/cell, 3 = 11-15 dots/cell, 4 = &gt;16 dots/cell. H-score (100-400) capturing the percentage of tumor cells at each staining level was calculated and correlated with clinical and tumour characteristics. Results: NCSTN high H-score &gt;120 correlated with high proliferative index (Ki67) (p = 0.002), high nuclear pleomorphism (p = 0.03) and mitotic score (p = 0.02) and membranous expression of the NCSTN protein (p = 0.05). It further correlated with cytoplsmic BRCA1 positivity (p = 0.025), which is associated with BrCa cell invasion. Importantly, in Kaplan-Meier analyses NCSTN Score&gt;120 conferred a higher probability of metastatic relapse at 10-year follow up (p = 0.019), and retained significance in the Cox regression multivariate analysis, along with tumor grade, stage and size (p = 0.04). Conclusion: RNAScope successfully detected NCSTN mRNA in paraffin embedded BrCa tissues. High NCSTN RNAScope levels may be a novel independent prognostic factor in this patient cohort and one that correlates with established markers of aggressive disease. We will also present data on anti-NCSTN mAb efficacy in cell systems based on NCSTN RNAScope score. We propose that detection of high NCSTN levels by RNAScope in primary BrCa removed at surgery or in subsequent biopsies of disease relapse can be further developed to serve as a clinical companion diagnostic test to assess patient eligibility for treatment using anti-NCSTN therapy.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-05-28.

Potentially avoidable emergency department attendance: interview study of patients' reasons for attendance

OBJECTIVES

To explore the reasons for attendance at the emergency department (ED) by patients who could have been managed in an alternative service and the rate of acute admissions to one acute hospital.

DESIGN

Interview study.

SETTING

One acute hospital (University Hospitals of Leicester) in the East Midlands.

PARTICIPANTS

23 patients and/or their carers.

METHODS

A purposive sample of patients attending the ED and the linked urgent care centre was identified and recruited. Patients in the sample were approached by a clinician and a researcher and invited to take part in an interview. Patients of different ethnicities and from different age groups, arriving at the ED via different referral routes (self-referral, emergency ambulance, GP referral, out-of-hours services) and attending at different times of the day and night were included. The interviews were recorded and transcribed with the individuals' permission and analysed using the framework analysis approach.

RESULTS

Patients' anxiety or concern about the presenting problem, the range of services available to the ED and the perceived efficacy of these services, patients' perceptions of access to alternative services including general practice and lack of alternative pathways were factors that influenced the decision to use the ED.

CONCLUSIONS

Access to general practice, anxiety about the presenting problem, awareness and perceptions of the efficacy of the services available in the ED and lack of alternative pathways are important predictors of attendance rates.

Characteristics of general practices associated with emergency-department attendance rates: a cross-sectional study

BACKGROUND

Strategies are needed to contain emergency-department attendance. Quality of care in general practice might influence the use of emergency departments, including management of patients with chronic conditions and access to consultations.

AIM

The aim was to determine whether emergency-department attendance rates are lower for practices with higher quality and outcomes framework performance and lower for practices with better patient reported access.

DESIGN

A cross-sectional study.

SETTING

Two English primary-care trusts, Leicester City and Leicestershire County and Rutland, with 145 general practices.

METHOD

Using data on attendances at emergency departments in 2006/2007 and 2007/2008, a practice attendance rate was calculated for each practice. In a hierarchical negative binomial regression model, practice population characteristics (deprivation, proportion of patients aged 65 or over, ethnicity, gender) and practice characteristics (total list size, distance from the emergency department, quality and outcomes framework points, and variables measuring satisfaction with access) were included as potential explanatory variables.

RESULTS

In both years, greater deprivation, shorter distance from the central emergency department, lower practice list size, white ethnicity and lower satisfaction with practice telephone access were associated with higher emergency-department attendance rates.

CONCLUSIONS

Performance as indicated by the quality and outcomes framework did not predict rates of attendance at emergency departments, but satisfaction with telephone access did. Consideration should be given to improving access to some general practices to contain the use of emergency departments.

FGF-23 and PTH levels in patients with acute kidney injury: A cross-sectional case series study

Background

Fibroblast growth factor-23 (FGF-23), a novel regulator of mineral metabolism, is markedly elevated in chronic kidney disease and has been associated with poor long-term outcomes. However, whether FGF-23 has an analogous role in acute kidney injury is unknown. The goal of this study was to measure FGF-23 levels in critically ill patients with acute kidney injury to determine whether FGF-23 levels were elevated, as in chronic kidney disease.

Methods

Plasma FGF-23 and intact parathyroid hormone (PTH) levels were measured in 12 patients with acute kidney injury and 8 control subjects.

Results

FGF-23 levels were significantly higher in acute kidney injury cases than in critically ill subjects without acute kidney injury, with a median FGF-23 level of 1948 RU/mL (interquartile range (IQR), 437-4369) in cases compared with 252 RU/mL (IQR, 65-533) in controls (p = 0.01). No correlations were observed between FGF-23 and severity of acute kidney injury (defined by the Acute Kidney Injury Network criteria); among patients with acute kidney injury, FGF-23 levels were higher in nonsurvivors than survivors (median levels of 4446 RU/mL (IQR, 3455-5443) versus 544 RU/mL (IQR, 390-1948; p = 0.02). Severe hyperparathyroidism (defined as intact PTH >250 mg/dL) was present in 3 of 12 (25%) of the acute kidney injury subjects versus none of the subjects without acute kidney injury, although this result did not meet statistical significance.

Conclusions

We provide novel data that demonstrate that FGF-23 levels are elevated in acute kidney injury, suggesting that FGF-23 dysregulation occurs in acute kidney injury as well as chronic kidney disease. Further studies are needed to define the short- and long-term clinical effects of dysregulated mineral metabolism in acute kidney injury patients.

Characteristics of general practices associated with emergency admission rates to hospital: a cross-sectional study

OBJECTIVES

To identify characteristics of general practices associated with emergency hospital admission rates, and determine whether levels of performance and patient reports of access are associated with admission rates.

DESIGN

A cross-sectional study.

SETTING

Two primary care trusts (Leicester City and Leicestershire County and Rutland) in the East Midlands of England.

PARTICIPANTS

145 general practices.

METHODS

Hospital admission data were used to calculate the rate of emergency admissions from 145 practices, for two consecutive years (2006/7 and 2007/8). Practice characteristics (size, distance from principal hospital, quality and outcomes framework performance data, patient reports of access to their practices) and patient characteristics (deprivation, ethnicity, gender and age), were used as predictors in a two-level hierarchical model, developed with data for 2007/8, and evaluated against data for 2006/7.

RESULTS

Practice characteristics (shorter distance from hospital, smaller list size) and patient characteristics (higher proportion of older people, white ethnicity, increasing deprivation, female gender) were associated with higher admission rates. There was no association with quality and outcomes framework domains (clinical or organisation), but there was an association between patients reporting being able to see a particular general practitioner (GP) and admission rates. As the proportion of patients able to consult a particular GP increased, emergency admission rates declined.

CONCLUSIONS

The patient characteristics of deprivation, age, ethnicity and gender are important predictors of admission rates. Larger practices and greater distance from a hospital have lower admission rates. Being able to consult a particular GP, an aspect of continuity, is associated with lower emergency admission rates.

Mutations in FAM20C are associated with lethal osteosclerotic bone dysplasia (Raine syndrome), highlighting a crucial molecule in bone development

The generation and homeostasis of bone tissue throughout development and maturity is controlled by the carefully balanced processes of bone formation and resorption. Disruption of this balance can give rise to a broad range of skeletal pathologies. Lethal osteosclerotic bone dysplasia (or, Raine syndrome) is an autosomal recessive disorder characterized by generalized osteosclerosis with periosteal bone formation and a distinctive facial phenotype. Affected individuals survive only days or weeks. We have identified and defined a chromosome 7 uniparental isodisomy and a 7p telomeric microdeletion in an affected subject. The extent of the deleted region at the 7p telomere was established by genotyping microsatellite markers across the telomeric region. The region is delimited by marker D7S2563 and contains five transcriptional units. Sequence analysis of FAM20C, located within the deleted region, in six additional affected subjects revealed four homozygous mutations and two compound heterozygotes. The identified mutations include four nonsynonymous base changes, all affecting evolutionarily conserved residues, and four splice-site changes that are predicted to have a detrimental effect on splicing. FAM20C is a member of the FAM20 family of secreted proteins, and its mouse orthologue (DMP4) has demonstrated calcium-binding properties; we also show by in situ hybridization its expression profile in mineralizing tissues during development. This study defines the causative role of FAM20C in this lethal osteosclerotic disorder and its crucial role in normal bone development.

Magnetic resonance spectroscopy for measuring the biodistribution and in situ in vivo pharmacokinetics of fluorinated compounds: validation using an investigation of liver and heart disposition of tecastemizole

BACKGROUND AND OBJECTIVE

The study of biodistribution and in situ pharmacokinetics is a challenging, but sometimes very important, aspect of premarketing characterization of drugs. We aimed to develop a non-invasive fluorine magnetic resonance (MR) spectroscopic method for the absolute quantitation of a mono-fluorinated compound and of its metabolites in the heart and liver of healthy subjects for this purpose.

METHOD

We used fluorine MR spectroscopy (MRS) at 4 T (Tesla) and external standardization in an open label multiple-dose study. Twenty-three healthy adult subjects were enrolled in the study. The surface coil localized fluorine MR spectrum was monitored in the heart and liver at baseline and after oral administration of multiple doses of tecastemizole. Steady-state measurements were made at set time points that depended upon dose, and washout measurements were made only on subjects in which in vivo fluorine signal was observed.

RESULTS AND DISCUSSION

At 4 T, under the given experimental conditions, the method had a lower limit of quantitation (LLOQ) of about 2.6 microm and a limit of detection (LOD) of about 0.3 microm for solution state samples (linewidth approximately 15 Hz). The measurement reproducibility was 6.4% using a 50 microm phantom. The effect of MR operator and spectral analyst on the calculated calibration curve slope was small, with inter-rater correlation coefficients of 0.999 and 0.998 respectively. MR signal from fluorine-containing tecastemizole-related moieties was observed in situ only at day 8 in the liver of three of five subjects dosed at 270 mg/day. The average in situ concentration was estimated to be 58+/-22 microm, with an average test-retest reproducibility of 216%. Extrapolating the in vitro results to human measurements, with an approximate linewidth of 250 Hz, predicts in situ LOD and LLOQ values of approximately 6 and 44 microm respectively. However, the human study had a fluorine MRS LOD of approximately 20 microm. The decrease in sensitivity and the increase in variability of the in vivo, in situ measurements compared with the validation study most likely arose from coil placement and incomplete rephasing of the MR signal by the respiratory phase compensation method.

CONCLUSION

The measured concentrations were the lowest ever recorded for a multi-dose exogenous mono-fluorinated compound in the human liver using a validated fluorine MR quantitation method. The proposed non-invasive MR method for studying the biodistribution and in situ pharmacokinetics of mono-fluorinated compounds in the liver and heart should have broader application to the development of non-invasive biomarkers.

Establishing a rural Emergency Medical Retrieval Service

In 2004 the Argyll and Clyde health board established the Emergency Medical Retrieval Service to support its rural community hospitals. This article describes both why the service was established and its aims. This service covers a geographically extensive area, with approximately 85,000 people living in remote locations. Rural general practitioners in six community hospitals provide initial patient assessment and resuscitation. Providing emergency care and safe transfer of seriously ill and injured patients presenting to these community hospitals is a significant challenge. All parties involved felt that there was a need to provide a service to transport critically ill and injured patients from these remote locations to definitive care. The idea of the team is to bring the resuscitation room to the patient in the rural setting. With this aim and in order to implement the Intensive Care Society guidelines for the transport of critically ill patients, it was decided that consultants in Emergency Medicine and Anaesthetics with an interest in critical care would staff the service medically. This service is unique within the UK and the authors aim to report our findings from ongoing research and audit in future papers.

Blood flow and red blood cell deformation in nonuniform capillaries: effects of the endothelial surface layer

OBJECTIVE

A theoretical model is used to examine the mechanics of red blood cell (RBC) motion in nonuniform capillaries. The model includes effects of the endothelial surface layer (ESL), which is a layer of macromolecules adjacent to the endothelium and which impedes plasma flow.

METHODS

The motion of an RBC traversing a capillary with diameter varying sinusoidally between 5.4 microm and 7.4 microm is simulated numerically. The ESL is assumed to be 0.7-microm wide and deformable. Axisymmetric RBC shapes are assumed. Lubrication theory is used to analyze the motion of plasma around the RBC and through the ESL.

RESULTS

In a nonuniform capillary with no ESL, moving RBCs undergo large transient deformations and predicted flow resistance is substantially higher than in a uniform capillary with the same mean diameter. The presence of a deformable ESL reduces the transient fluid shear stresses and deformations experienced by RBCs traversing a nonuniform capillary. With an ESL, the increase in flow resistance resulting from nonuniformity is less than twofold versus three- to fourfold with no ESL in vessel geometries with the same ESL-free luminal region.

CONCLUSIONS

The presence of the ESL reduces the impact of capillary irregularity on flow resistance and may protect RBCs traversing irregular capillaries from damage due to large, rapidly fluctuating external stresses.

Vastus medialis obliquus and vastus lateralis activity in open and closed kinetic chain exercises in patients with patellofemoral pain syndrome: an electromyographic study

OBJECTIVES

To evaluate the electromyographic activities of vastus medialis obliquus (VMO) and vastus lateralis (VL) muscles in open and closed kinetic chain exercises in subjects with patellofemoral pain syndrome (PFPS).

DESIGN

Case-controlled study.

SETTING

Rehabilitation science center in a tertiary medical center.

PARTICIPANTS

Ten patients with bilateral knee pain diagnosed with PFPS and 10 healthy volunteers.

INTERVENTIONS

Subjects performed open kinetic chain exercise on an isokinetic dynamometer and closed kinetic chain exercise by squat-to-stand and stand-to-squat tasks. Surface electromyography was done for the VMO and VL muscles.

MAIN OUTCOME MEASURES

VMO/VL ratios were calculated after normalization of muscle activities.

RESULTS

The VMO/VL ratios of PFPS subjects were significantly lower than were those of unimpaired subjects during knee isokinetic closed kinetic chain exercises (p = .047). However, there was no statistical difference in VMO/VL ratio between subjects with and without PFPS during closed kinetic chain exercises (p = .623). Maximum VMO/VL ratio was obtained at 60 degrees knee flexion in closed kinetic chain exercise.

CONCLUSION

In closed kinetic chain exercises, more selective VMO activation can be obtained at 60 degrees knee flexion. Maximal VMO/VL ratio was observed at this knee flexion angle, and muscle contraction intensity was also greatest.

Quantitative and qualitative assessment of women's experience of a one-stop menstrual clinic in comparison with traditional gynaecology clinics

OBJECTIVE

A quantitative and qualitative evaluation of the views of patients attending two types of clinics for menstrual disorders.

METHODS

Semi-structured qualitative interview and quantitative questionnaire.

SETTING

Five traditional general gynaecology clinics and a one-stop menstrual clinic, where investigations are performed and results given to patients on the same day.

PARTICIPANTS

Two hundred and thirty-nine women (126 from the gynaecology clinic and 113 from the menstrual clinic) were recruited into the quantitative study; 18 and 26 patients from the gynaecology and the menstrual clinic, respectively, were interviewed for the qualitative study.

MAIN OUTCOME MEASURES

Women's views about their care and progress towards resolution of their problem.

RESULTS

Following the initial consultation, 106 (84%) of the gynaecology clinic, and 98 (87%) of the menstrual clinic patients completed the first part of the questionnaire. Of those, 75 (71%) and 79 (81%) patients from the two types of clinic, respectively, completed a follow up questionnaire one year later. There were statistically significant differences in all the components of the first part of the questionnaire (information, continuity, waiting, organisation, and limbo) in favour of the one-stop menstrual clinic. After one year, there was a statistically significant difference in one of the components, patient centeredness, but not in overall process co-ordination. The interviews showed that patients attending the menstrual clinic appreciated getting the results of their investigations on the same day. They also found the organisation of the one-stop menstrual clinic more closely suited to their needs and as a result were more likely to feel they were making progress.

CONCLUSION

Women were consistently more positive about their experience in the one-stop clinic. One-stop clinics organised to meet the needs of patients might be appropriate for other clinical conditions. The combination of quantitative and qualitative methods is an effective method of assessing patients' views of health services.

Effect of the endothelial surface layer on transmission of fluid shear stress to endothelial cells

Responses of vascular endothelial cells to mechanical shear stresses resulting from blood flow are involved in regulation of blood flow, in structural adaptation of vessels, and in vascular disease. Interior surfaces of blood vessels are lined with a layer of bound or adsorbed macromolecules, known as the endothelial surface layer (ESL). In vivo investigations have shown that this layer has a width of order 1 microm, that it substantially impedes plasma flow, and that it excludes flowing red blood cells. Here, the effect of the ESL on transmission of shear stress to endothelial cells is examined using a theoretical model. The layer is assumed to consist of a matrix of molecular chains extending from the surface, held in tension by a slight increase in colloid osmotic pressure relative to that in free-flowing plasma. It is shown that, under physiological conditions, shear stress is transmitted to the endothelial surface almost entirely by the matrix, and fluid shear stresses on endothelial cell membranes are very small. Rapid fluctuations in shear stress are strongly attenuated by the layer. The ESL may therefore play an important role in sensing of shear stress by endothelial cells.

Motion of red blood cells in a capillary with an endothelial surface layer: effect of flow velocity

Interior surfaces of capillaries are lined with macromolecules forming an endothelial surface layer (ESL). A theoretical model is used to investigate effects of flow velocity on motion and axisymmetric deformation of red blood cells in a capillary with an ESL. Cell deformation is analyzed, including effects of membrane shear and bending elasticity. Plasma flow around the cell and through the ESL is computed using lubrication theory. The ESL is represented as a porous layer that exerts compressive forces on red blood cells that penetrate it. According to the model, hydrodynamic pressures generated by plasma flow around the cell squeeze moving red blood cells into narrow elongated shapes. If the ESL is 0.7 microm wide, with hydraulic resistivity of 2 x 10(8) dyn x s x cm(-4), and exerts a force of 20 dyn/cm2, predicted variation with flow velocity of the gap width between red blood cell and capillary wall agrees well with observations. Predicted gap at a velocity of 0.1 mm/s is approximately 0.6 microm vs. approximately 0.2 microm with no ESL. Predicted flow resistance increases markedly at low velocities. The model shows that exclusion of red blood cells from the ESL in flowing capillaries can result from hydrodynamic forces generated by plasma flow through the ESL.

Are self-expanding metal mesh stents useful in the treatment of benign esophageal stenoses and fistulas? An experience of four cases

OBJECTIVE

The aim of this study was to review the long-term results of treating benign esophageal fistula and stenosis using self-expanding metal stents.

METHODS

We treated four patients using covered mesh or coiled stents. We removed the stents electively in two patients (one endoscopically and one during planned partial esophagectomy) and unexpectedly in one patient who developed bleeding. One stent migrated and required laparotomy for removal.

RESULTS

Placement of self-expanding metal stents successfully sealed the benign fistula in two patients and reestablished swallowing in two other patients with complicated achalasia. Two patients were swallowing normally on long-term follow-up, one died of the underlying disease, and one required gastrostomy.

CONCLUSION

Temporary use of self-expanding metal stents as a feasible option for treating benign esophageal stenosis and fistula in patients who have failed other conventional treatments.

Theoretical simulation of oxygen transport to brain by networks of microvessels: effects of oxygen supply and demand on tissue hypoxia

OBJECTIVE

Simulations of oxygen delivery by a three-dimensional network of microvessels in rat cerebral cortex were used to examine how the distribution of partial pressure of oxygen (PO2) in tissue depends on blood flow and oxygen consumption rates.

METHODS

Network geometry was deduced from previously published scanning electron micrographs of corrosion casts. A nonlinear least-squares method, using images obtained at three different angles, was used to estimate vessel locations. The network consisted of 50 segments in a region 140 microm x 150 microm x 160 microm. A Green's function method was used to predict the PO2 distribution. Effects of varying perfusion and consumption were examined, relative to a control state with consumption 10 cm3O2/100 g per min and perfusion 160 cm3/100 g per min.

RESULTS

In the control state, minimum tissue PO2, was 7 mm Hg. A Krogh-type model with the same density of vessels, but with uniform spacing, predicted a minimum tissue PO2 of 23 mm Hg. For perfusion below 60% of control, tissue hypoxia (PO2 <1 mm Hg) was predicted. When perfusion was reduced by 75%, the resulting hypoxia could be eliminated by a 31% reduction in oxygen consumption rate.

CONCLUSIONS

The simulations suggest that tissue hypoxia resulting from a severe decrease in brain perfusion, as can occur in stroke, may be avoided by a moderate decrease in oxygen consumption rate.

Quantitation of N-(3,5-dichloropyrid-4-yl)-3-cyclopentyloxy-4-methoxybenzamide and 4-amino-3,5-dichloropyridine in rat and mouse plasma by LC/MS/MS

The metabolism of N-(3,5-dichloropyrid-4-yl)-3-cyclopentyloxy-4-methoxybenzamide (RP73401), a phosphodiesterase IV (PDE IV) inhibitor is extensive (unpublished); however, until recently, studies for this compound did not report 4-amino-3,5-dichloropyridine (ADCP) as a metabolite either in vitro or in vivo. This prompted a reinvestigation into the metabolism of RP73401 in rats and mice using mass spectrometry. The results of the reinvestigation confirmed that 4-amino-3,5-dichloropyridine was formed via the metabolism of RP73401 both in vitro and in vivo. In order to further investigate RP73401 hydrolysis in vivo, a liquid chromatography/mass spectrometry assay was developed and validated for the simultaneous determination of RP73401 and ADCP in rat and mouse plasma. The method used Waters Oasis HLB brand solid phase extraction cartridges to isolate the analytes (RP73401 and ADCP) and internal standard from the plasma. HPLC chromatographic separation was achieved using a Zorbax SB C18 HPLC column and detection was accomplished using positive ion atmospheric pressure chemical ionization tandem mass spectroscopy in multiple reaction monitoring (MRM) mode. The assay was developed and validated over the range of 0.5-100 ng ml(-1) for RP73401 and 5-500 ng ml(-1) for ADCP using 0.050 ml of plasma. The assay proved to be sensitive, accurate, precise and specific for RP73401 and ADCP. Intraday and interday quality control results routinely showed accuracy and precision to be within +/- 20%. This LC/MS/MS method was subsequently employed to investigate the hydrolysis of RP73401 in the rat and mouse, and determine the effects of tri-o-tolyl phosphate (TOTP, a carboxylesterase inhibitor) preadministration on the hydrolysis reaction in the rat.

Fab fragments directed against laminin 5 induce subepidermal blisters in neonatal mice

Patients with one form of cicatricial pemphigoid have IgG autoantibodies directed against laminin 5 (alpha3beta3gamma2), an adhesion protein in epidermal basement membrane. Anti-laminin 5 autoantibodies are not found in patients with other skin or mucosal diseases and hence serve as a specific marker for this autoimmune blistering disorder. The demonstration that experimental and patient anti-laminin 5 IgG are pathogenic in animal models indicated that such autoantibodies are central to disease pathophysiology. To investigate further the role of antibody valence and complement in triggering lesion formation in vivo, rabbit anti-laminin 5 (or normal, control) Fab fragments were passively transferred to neonatal BALB/c mice. Mice receiving anti-laminin 5 Fab fragments developed, in a dose-related fashion, circulating anti-basement membrane antibodies, deposits of immunoreactive rabbit IgG (but not murine C3) in epidermal basement membranes, and subepithelial blisters of skin and mucous membranes. Such alterations were not observed in mice treated with equivalent concentrations of normal rabbit Fab fragments. These studies demonstrated that neither complement activation nor cross-linking of laminin 5 in epidermal basement membranes was required for induction of subepidermal blister formation in this animal model of a human autoimmune bullous disease.

Human anti-laminin 5 autoantibodies induce subepidermal blisters in an experimental human skin graft model

Patients with one form of cicatricial pemphigoid have IgG antibasement membrane autoantibodies against laminin 5 (alpha3beta3gamma2). Although passive transfer of rabbit anti-laminin 5 IgG to neonatal mice has been shown to induce subepidermal blisters that mimic those in patients, it has not been possible to directly assess the pathogenic activity of human autoantibodies in this animal model because the latter do not bind murine skin. To address this question, a disease model in adult mice as well as SCID mice bearing human skin grafts was developed. Adult BALB/C mice challenged with rabbit anti-laminin 5 IgG developed, in a concentration-related fashion, erythema, erosions, and crusts surrounding injection sites, histologic evidence of noninflammatory, subepidermal blisters, and deposits of rabbit IgG and murine C3 in epidermal basement membranes. Anti-laminin 5 IgG also induced subepidermal blisters in: adult complement-, mast cell-, and immuno-deficient mice; adult BALB/C mice pretreated with dexamethasone; and human skin grafts on SCID mice. Alterations did not develop in matching controls challenged with identical amounts of purified normal rabbit IgG or bovine serum albumin. Using this adult mouse model, human skin grafts on SCID mice were challenged with purified IgG from patients with alpha subunit-specific, anti-laminin 5 autoantibodies, or normal controls. Patient (but not control) IgG induced epidermal fragility as well as noninflammatory, subepidermal blisters in grafted human (but not adjacent murine) skin. Moreover, whereas all mice that received patient autoantibodies had anti-laminin 5 IgG in their circulation, deposits of human IgG were present only in the epidermal basement membranes of grafts. Interestingly, these in situ and circulating autoantibodies were predominately of the IgG4 subclass. These studies demonstrate that human anti-laminin 5 autoantibodies are pathogenic in vivo and describe an animal model that can be used to define disease pathomechanisms and biologically important domains within this autoantigen.