Implications of variability on medical device chemical equivalence assessment

Chemical equivalence testing can be used to assess the biocompatibility implications of a materials or manufacturing change for a medical device. This testing can provide a relatively facile means to evaluate whether the change may result in additional or different toxicological concerns. However, one of the major challenges in the interpretation of chemical equivalence data is the lack established criteria for determining if two sets of extractables data are effectively equivalent. To address this gap, we propose a two-part approach based upon a relatively simple statistical model. First, the probability of a false positive conclusion, wherein there is an incorrectly perceived increase for a given analyte in the comparator relative to the baseline device, can be reduced to a prescribed level by establishing an appropriate acceptance criterion for the ratio of the observed means. Second, the probability of a false negative conclusion, where an actual increase in a given analyte cannot be discerned from the test results, can be minimized by specifying a limiting value of applicability based on the margin of safety (MoS) of the analyte. This approach provides a quantitative, statistically motivated method to interpret chemical equivalence data, despite the relatively high intrinsic variability and small number of replicates typically associated with a chemical characterization evaluation.

Non-targeted analysis (NTA) and suspect screening analysis (SSA): a review of examining the chemical exposome

Non-targeted analysis (NTA) and suspect screening analysis (SSA) are powerful techniques that rely on high-resolution mass spectrometry (HRMS) and computational tools to detect and identify unknown or suspected chemicals in the exposome. Fully understanding the chemical exposome requires characterization of both environmental media and human specimens. As such, we conducted a review to examine the use of different NTA and SSA methods in various exposure media and human samples, including the results and chemicals detected. The literature review was conducted by searching literature databases, such as PubMed and Web of Science, for keywords, such as "non-targeted analysis", "suspect screening analysis" and the exposure media. Sources of human exposure to environmental chemicals discussed in this review include water, air, soil/sediment, dust, and food and consumer products. The use of NTA for exposure discovery in human biospecimen is also reviewed. The chemical space that has been captured using NTA varies by media analyzed and analytical platform. In each media the chemicals that were frequently detected using NTA were: per- and polyfluoroalkyl substances (PFAS) and pharmaceuticals in water, pesticides and polyaromatic hydrocarbons (PAHs) in soil and sediment, volatile and semi-volatile organic compounds in air, flame retardants in dust, plasticizers in consumer products, and plasticizers, pesticides, and halogenated compounds in human samples. Some studies reviewed herein used both liquid chromatography (LC) and gas chromatography (GC) HRMS to increase the detected chemical space (16%); however, the majority (51%) only used LC-HRMS and fewer used GC-HRMS (32%). Finally, we identify knowledge and technology gaps that must be overcome to fully assess potential chemical exposures using NTA. Understanding the chemical space is essential to identifying and prioritizing gaps in our understanding of exposure sources and prior exposures. IMPACT STATEMENT: This review examines the results and chemicals detected by analyzing exposure media and human samples using high-resolution mass spectrometry based non-targeted analysis (NTA) and suspect screening analysis (SSA).

Real-World Effectiveness Study of Benralizumab for Severe Eosinophilic Asthma: ZEPHYR 2

BACKGROUND

Benralizumab is an mAb therapy for severe eosinophilic asthma. Real-world data on its clinical impact in various patient populations such as patients with varying eosinophil levels, previous biologic use, and extended follow-up in the United States are limited.

OBJECTIVE

To determine the effectiveness of benralizumab in different asthmatic patient cohorts and its long-term clinical impact.

METHODS

Patients with asthma treated with benralizumab from November 2017 to June 2019 with 2 or more exacerbations in the 12 months before benralizumab initiation (index) were included in this pre-post cohort study that used medical, laboratory, and pharmacy US insurance claims. Asthma exacerbation rates in the 12 months pre and post index were compared. Nonmutually exclusive patient cohorts were defined by blood eosinophil counts (<150, ≥150, 150-<300, <300, and ≥300 cells/μL), a switch from another biologic, or follow-up for 18 or 24 months post index.

RESULTS

There were 429 patients in the eosinophil cohort, 349 in the biologic-experienced cohort, and 419 in the extended follow-up cohort. In all eosinophil cohort subgroups, the asthma exacerbation rate decreased from 3.10-3.55 per patient-year (PPY) pre index to 1.11-1.72 PPY post index (52%-64% decrease; P < .001). Similar decreases were observed in patients switching from omalizumab (3.25 to 1.25 PPY [62%]) or mepolizumab (3.81 to 1.78 PPY [53%]) to benralizumab and those followed up for 18 months (3.38 to 1.18 PPY [65%]) or 24 months (3.38 to 1.08 PPY [68%]) (all P < .001). In the extended follow-up cohort, 39% and 49% had no exacerbations in the 0 to 12 months and the 12 to 24 months post index, respectively.

CONCLUSIONS

Benralizumab achieved significantly improved asthma control in real-world patients with different blood eosinophil counts, including eosinophil counts ranging from less than 150 to greater than or equal to 300 cells/μL, switching from other biologics, or treated for up to 24 months.

Modeling extraction of medical device polymers for biocompatibility evaluation

Extraction testing is critical for biocompatibility evaluation of medical devices, whether to generate samples for biological testing or form the basis for toxicological risk assessment. However, it is not always clear how to compare extraction testing between different extraction conditions and sample geometries. We employ a physics-based model to elucidate the theoretical impact of extraction conditions, sample geometry and material properties on extraction efficiency (M/M⁰) and extract concentration (C/C⁰) for single-step and iterative/exhaustive extraction test methods. The model is specified by three parameters: thermodynamic contributions (Ψ), kinetic contributions (τ), and number of extraction iterations (N). We find that over the range of typical parameters for single-step extractions, M/M⁰ only approaches one (complete exhaustion) for relatively large values of Ψ (≥10) and τ(≥1). Further, the model suggests that test article geometry and solvent volume can have a dramatic and sometimes opposing effect on M/M⁰ and C/C⁰. Our results imply that iterative extractions can be approximated as a single-step extraction with scaled parameters Ψ' = ΨN and τ' = τN. The model provides a framework to reduce the biocompatibility evaluation test burden by optimizing test article and extraction condition selection and guiding development of new test protocols.

Impact on hospitalizations of long-term versus short-term therapy with sodium zirconium cyclosilicate during routine outpatient care of patients with hyperkalemia: the recognize I study

BACKGROUND

Hyperkalemia is associated with increased healthcare resource utilization (HRU). This study evaluated the impact of sodium zirconium cyclosilicate (SZC) use on HRU in outpatients with hyperkalemia.

RESEARCH DESIGN AND METHODS

A retrospective noncomparative study using claims data from the HealthVerity warehouse, which included outpatients in the United States who initiated SZC between January and December 2019 (index date) with ≥6 months' continuous coverage before (baseline) and after (follow-up) the index date (total coverage of 12 months). The study aimed to describe HRU with long-term and short-term SZC (defined as >90 and ≤90 days' supply, respectively, during 180 days' follow-up) and identify characteristics associated with long-term versus short-term therapy.

RESULTS

Of 1153 patients, 748 (64.9%) received short-term and 405 (35.1%) received long-term therapy. During follow-up, lower proportions of patients on long-term versus short-term therapy had hyperkalemia-related hospitalizations (10.1% vs 15.1%; P < 0.05) and all-cause hospitalizations (22.5% vs 29.3%; P < 0.05). Hyperkalemia-related and all-cause hospitalization proportions were 33.0% and 23.3% lower, respectively. Predictors of long-term therapy included stage 3 chronic kidney disease.

CONCLUSIONS

Approximately one-third of patients with hyperkalemia received long-term SZC therapy. Hyperkalemia-related and all-cause hospitalization proportions were lower with long-term therapy, although further confirmatory studies are needed.

Impact of benralizumab on asthma exacerbation-related medical healthcare resource utilization and medical costs: results from the ZEPHYR 2 study

BACKGROUND AND AIM

Benralizumab is a biologic add-on treatment for severe eosinophilic asthma that can reduce the rate of asthma exacerbations, but data on the associated medical utilization are scarce. This retrospective study evaluated the economic value of benralizumab by analyzing healthcare resource utilization (HRU) and medical costs in a large patient population in the US.

METHODS

Insurance claims data (11/2016-6/2020) were analyzed. A pre-post design was used to compare asthma exacerbation rates, medical HRU and medical costs in the 12 months pre vs. post index (day after benralizumab initiation). Patients were aged ≥12 years, with ≥2 records of benralizumab and ≥2 asthma exacerbations pre index, and constituted non-mutually exclusive cohorts: biologic-naïve, biologic-experienced (switched from omalizumab or mepolizumab to benralizumab), or with extended follow-up (18 or 24 months).

RESULTS

In all cohorts (mean age 51-53 years; 67-70% female; biologic-naïve, N = 1,292; biologic-experienced, N = 349; 18-month follow-up, N = 419; 24-month follow-up, N = 156), benralizumab treatment reduced the rate of asthma exacerbation by 53-68% (p < .001). In the biologic-naïve cohort, inpatient admissions decreased by 58%, emergency department visits by 54%, and outpatient visits by 58% post index (all p < .001), with similar reductions in exacerbation-related medical HRU in other cohorts. Exacerbation-related mean total medical costs decreased by 51% in the biologic-naïve cohort ($4691 pre-index, $2289 post-index), with cost differences ranging from 16% to 64% across other cohorts (prior omalizumab: $2686 to $1600; prior mepolizumab: $5990 to $5008; 18-month: $3636 to $1667; 24-month: $4014 to $1449; all p < .001). Medical HRU and cost reductions were durable, decreasing by 64% in year 1 and 66% in year 2 in the 24 month follow-up cohort.

CONCLUSION

Patients treated with benralizumab with prior exacerbations experienced reductions in asthma exacerbations and exacerbation-related medical HRU and medical costs regardless of prior biologic use, with the benefits observed for up to 24 months after treatment initiation.

Impact of trilaciclib on multilineage chemotherapy-induced myelosuppression events in patients with extensive-stage small cell lung cancer: Post-hoc analyses of data from randomized clinical trials

8568

Background: Trilaciclib is a short-acting CDK4/6 inhibitor administered prior to chemotherapy for multilineage myeloprotection. Reduced occurrence of chemotherapy-induced myelosuppression (CIM) events across neutrophil, red blood cell, and platelet lineages was reported in 3 Phase 2 clinical trials of trilaciclib versus placebo in patients with extensive-stage small cell lung cancer (ES-SCLC). In this post-hoc trial analysis, we further assessed the impact of trilaciclib on the occurrence of single and concurrent multilineage CIM events. Methods: Analyses were conducted separately by line of chemotherapy. In the first-line (1L) setting, pooled data from the G1T28-05 and G1T28-02 trials, in which trilaciclib or placebo was administered prior to etoposide, carboplatin, and atezolizumab [E/P/A] and E/P, respectively, were used. In the 2/3L setting, analyses were based on data from the G1T28-03 trial where patients received trilaciclib or placebo prior to topotecan. The proportion of patients with single and concurrent multilineage CIM events and incidence rate were estimated per cycle and during the first 4 cycles of chemotherapy. Severe (grade ≥ 3 per CTCAE definition) CIM events of neutropenia (SN), anemia (SA), and thrombocytopenia (ST) were assessed. Concurrent CIM events were defined as having 2 or 3 lineage-specific CIM events overlap for ≥ 1 day. As sensitivity analyses, the occurrence of CIM events in patients with ES-SCLC receiving 1L treatment in the G1T28-05 and G1T28-02 studies was analyzed separately. Results: Compared with placebo, fewer patients receiving trilaciclib had single-lineage CIM events and concurrent events in 2 or 3 lineages during cycles 1–4 of 1L chemotherapy using pooled data from G1T28-05 and G1T28-02 (Table). A similar trend was observed in the 2/3L setting. Generally, SN occurred more frequently in earlier cycles, whereas SA and ST tended to occur later. The sensitivity analysis in each individual 1L trial yielded consistent results with the pooled analysis. Conclusions: Patients with ES-SCLC receiving trilaciclib prior to chemotherapy had fewer single and concurrent multilineage CIM events than patients receiving placebo. Clinical trial information: NCT03041311, NCT02499770, NCT02514447. [Table: see text]

Association of Calcium and Phosphate Levels with Incident Chronic Kidney Disease in Patients with Hypoparathyroidism: A Retrospective Case-Control Study

OBJECTIVE

Reasons for the increased incidence of chronic kidney disease (CKD) in patients with chronic hypoparathyroidism are poorly understood. This study evaluated associations between levels of albumin-corrected serum calcium, serum phosphate, and calcium-phosphate product and the odds of CKD development in patients with chronic hypoparathyroidism.

DESIGN

A retrospective nested case-control study of adult patients with chronic hypoparathyroidism who had ≥1 prescription for calcitriol who developed CKD and matched controls who did not develop CKD were selected from the IBM® Explorys electronic medical record database. Patients. The study included a cohort of 300 patients for the albumin-corrected serum calcium analysis and 80 patients for the serum phosphate and calcium-phosphate product analyses. Measurements. We examined associations between albumin-corrected serum calcium, serum phosphate and calcium-phosphate product levels, and the risk of devloping CKD (defined as ≥2 outpatient estimated glomerular filtration values <60 mL/min/1.73 m² occuring ≥3 months apart or ≥1 diagnostic code for CKD stages 3-5).

RESULTS

Individuals who had ≥67% of albumin-corrected serum calcium measurements outside, above, or below the study-defined range (2.00-2.25 mmol/L [8.0-9.0 mg/dL]) had 3.5-, 2.9-, and 2.7-fold higher odds of developing CKD (adjusted odds ratios [95% CI]: 3.46 [1.82-6.56], 2.85 [1.30-6.28], and 2.68 [1.16-6.15]), respectively, compared with patients who had <33% of albumin-corrected calcium measurements in those ranges. There was no association between developing CKD and having any serum phosphate measurements or any calcium-phosphate product measurements above normal population ranges.

CONCLUSION

In adult patients with chronic hypoparathyroidism, a higher proportion of albumin-corrected calcium measurements outside of the 2.00-2.25 mmol/L (8.0-9.0 mg/dL) range was associated with higher odds of developing CKD.

Risk of Nephrolithiasis and Nephrocalcinosis in Patients with Chronic Hypoparathyroidism: A Retrospective Cohort Study

Introduction

Chronic hypoparathyroidism managed with conventional treatment, comprising oral administration of calcium and active vitamin D, has been associated with renal complications, including nephrolithiasis and nephrocalcinosis. Further larger-scale studies are needed to examine these risks. This study evaluated the risk of nephrolithiasis and nephrocalcinosis in patients with chronic hypoparathyroidism.

Methods

A retrospective cohort study using a managed care claims database in the United States from January 2007 to June 2017. Included patients were those with chronic hypoparathyroidism (excluding those receiving parathyroid hormone) and randomly selected patients without hypoparathyroidism over a maximum of 5-year follow-up. The main outcome measures were nephrolithiasis, identified by diagnosis codes or procedure codes for removing kidney stones, and nephrocalcinosis, identified by diagnosis codes.

Results

The nephrolithiasis analyses included 8097 adult patients with hypoparathyroidism and 40,485 adult patients without hypoparathyroidism. After excluding patients with a diagnosis of nephrocalcinosis at baseline, nephrocalcinosis analyses included 8051 patients with hypoparathyroidism and 40,466 patients without hypoparathyroidism. During 5 years of follow-up, patients with chronic hypoparathyroidism had significantly increased risk of nephrolithiasis and nephrocalcinosis in Kaplan–Meier analysis compared with patients without hypoparathyroidism (both P < 0.001). In the adjusted analyses, chronic hypoparathyroidism was associated with higher risks of nephrolithiasis (hazard ratio [HR], 1.81; 95% confidence interval [CI] 1.60–2.04) and nephrocalcinosis (HR, 6.94; 95% CI 4.41–10.92). A sensitivity analysis restricted to patients with at least one kidney imaging examination showed that 2.6% of patients (n = 59) with hypoparathyroidism and 0.5% of patients (n = 20) without hypoparathyroidism (ratio, 5.5; P < 0.001) developed nephrocalcinosis.

Conclusions

This large retrospective cohort study showed a statistically significant and clinically meaningful increased risk of nephrolithiasis and nephrocalcinosis in patients who have chronic hypoparathyroidism compared with those who do not have chronic hypoparathyroidism.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-021-01649-2.

Predicting Refractive Outcome of Small Incision Lenticule Extraction for Myopia Using Corneal Properties

Purpose

To investigate whether preoperative corneal topographic and biomechanical parameters (CTBPs) predict postoperative residual refractive error (RRE).

Methods

We retrospectively included 151 eyes from 151 patients of small-incision lenticule extraction (SMILE) with target RRE of plano and 3-month measurements of refractive error from Tianjin Eye Hospital. Multivariate linear/logistic regressions were performed to associate age, gender, preoperative refractive error, lenticule thickness, and CTBPs with postoperative RRE/the occurrence of myopic RRE ≤ −0.25 diopter (D). Stepwise regression was used for feature selection. Leave-one-cross-validation was used for model evaluation by the area under the receiver operating characteristic curve (AUC).

Results

From linear regression, more myopic RRE was associated with higher preoperative myopia, intraocular pressure (IOP), flattest curvature of anterior cornea (AC), and highest concavity deformation (HCD), and was associated with lower anterior elevation, anterior asphericity, steepest curvature of AC, and second applanation velocity. The occurrence of ≤ −0.25 D RRE was associated with higher myopia, IOP, posterior elevation and asphericity, flattest curvature of AC, first applanation velocity and HCD, and was associated with lower first applanation stiffness parameter, central corneal thickness, anterior elevation and asphericity, steepest curvature of AC, and second applanation velocity as well as thinner lenticule thickness. Compared to the baseline model using age, gender, and preoperative refractive error, adding CTBPs significantly (P < 0.001) improved the AUC performance to 0.771 from 0.615.

Conclusions

Postoperative outcomes of SMILE can be predicted by individual CTBPs.

Translational Relevance

Our findings could be used to customize a refractive nomogram based on individual corneal properties improving outcomes and patient satisfaction.

Electropolymerized Pyrrole-Based Conductive Polymeric Ionic Liquids and Their Application for Solid-Phase Microextraction

Pyrrole was covalently bonded to 1-methyl and 1-benzylimidazolium ionic liquids (ILs) via an N-substituted alkyl linkage to prepare electropolymerizable IL monomers with excellent thermal stability. The methylimidazolium IL, [pyrrole-C₆MIm]⁺, was then electropolymerized on macro- and microelectrode materials to form conductive polymeric IL (CPIL)-modified surfaces. Electrochemical characterization of a 1.6 mm diameter Pt disk electrode modified with poly[pyrrole-C₆MIm]⁺ demonstrated a selective uptake for an anionic redox probe while rejecting a cationic redox probe. Furthermore, electropolymerization of [pyrrole-C₆MIm]⁺ doped with single-walled carbon nanotubes (SWNT) on 125 μm platinum wires produced 42 μm thick poly[pyrrole-C₆MIm]⁺/SWNT films compared to 17 μm in the absence of SWNT and 5 μm for the previously reported poly[thiophene-C₆MIm]⁺ coatings. The poly[pyrrole-C₆MIm]⁺/SWNT films were prepared with reproducible thicknesses as well as thermal properties sufficient for high-temperature applications, such as solid-phase microextraction (SPME) with gas chromatographic analysis. The utilization of the CPIL sorbent materials in SPME experiments provided excellent extraction efficiencies and selectivity toward organic aromatic analytes. The CPIL sorbent coatings also yielded outstanding fiber-to-fiber reproducibility on the basis of extraction efficiencies and improved response for a range of analytes relative to commercial 100 μm poly(dimethylsiloxane) fibers when normalized for differences in film thickness. Poly[pyrrole-C₆MIm]⁺ CPIL coatings doped with SWNT are therefore promising new sorbent materials for SPME analyses.

Fractal Dimensional Analysis of Optical Coherence Tomography Angiography in Eyes With Diabetic Retinopathy

Purpose

We used fractal dimensional analysis to analyze retinal vascular disease burden in eyes with diabetic retinopathy using spectral-domain optical coherence tomography angiography (OCTA).

Methods

A retrospective study was performed of 13 eyes with diabetic retinopathy without diabetic macular edema and 56 control eyes. Optical coherence tomography angiography images were acquired using the RTVue XR Avanti. Automated segmentation was obtained through the superficial and deep capillary plexuses for each eye. Grayscale OCTA images were standardized and binarized using ImageJ. Fractal box-counting analyses were performed using Fractalyse. Fractal dimensions (FD) as well as software-generated vascular density analyses of the superficial and deep capillary plexuses were compared between diabetic and control eyes using 2-tailed t-tests and 1-way multivariate ANOVA (MANOVA) analyses.

Results

The superficial and deep plexuses from diabetic and control eyes were analyzed. The average FD for diabetic eyes was significantly lower than control eyes for the superficial (P = 4.513 × 10-3) and deep (P = 2.653 × 10-3) capillary plexuses. In diabetic eyes, the vascular density also was significantly reduced in the superficial (P = 8.068 × 10-5) and deep (P = 3.120 × 10-6) capillary plexuses. One-way MANOVA showed a significant difference between diabetic and control eyes.

Conclusions

The OCTA FD is significantly reduced in the superficial and deep capillary plexuses in eyes with diabetic retinopathy. Applying fractal analysis to OCTA imaging holds the potential to establish quantitative parameters for microvascular pathology.

The applied model of imagery use: Examination of moderation and mediation effects

The applied model of mental imagery use proposed an interaction effect between imagery type and imagery ability. This study had two aims: (a) the examination of imagery ability as a moderating variable between imagery type and dispositional flow, and (b) the testing of alternative mediation models. The sample consisted of 367 athletes from Scotland and Australia, who completed the Sport Imagery Questionnaire, Sport Imagery Ability Questionnaire, and Dispositional Flow Scale-2. Hierarchical regression analysis showed direct effects of imagery use and imagery ability on flow, but no significant interaction. Mediation analysis revealed a significant indirect path, indicating a partially mediated relationship (P = 0.002) between imagery use, imagery ability, and flow. Partial mediation was confirmed when the effect of cognitive imagery use and cognitive imagery ability was tested, and a full mediation model was found between motivational imagery use, motivational imagery ability, and flow. The results are discussed in conjunction with potential future research directions on advancing theory and applications.

Preoperative C-reactive protein predicts the severity and likelihood of complications following appendicectomy

INTRODUCTION

Diagnostic laparoscopy with appendicectomy (LA) has become the accepted method of investigation and treatment of appendicitis. However, concerns remain in cases of complicated appendicitis when many advocate conversion to an open procedure (LCOA) owing to the risk of complications. The aim of this study was to look for factors that could predict complications occurring in patients undergoing appendicectomy.

METHODS

Data inclusive of all consecutive appendicectomies over a two-year period were retrieved from the computerised theatre database. Clinical details including admission inflammatory markers, complications, severity (final pathology) and length of stay were collected from the discharge letter. Readmissions were identified as those hospital identifiers had a second set of admission dates and/or a second discharge letter.

RESULTS

During the 2-year study period, 517 appendicectomies were performed. Of these, 429 patients (83%) had LA and the remaining 88 (17%) had LCOA. The LA group had a mean age of 28 years (range: 2-86 years) and a mean C-reactive protein (CRP) level of 71 mg/l (range: 0-480 mg/l) while the LCOA group had a mean age of 46 years (range: 11-92 years) and a mean CRP level of 162 mg/l (range: 3-404 mg/l). These differences in age and CRP were significant (p<0.001). LA patients were less likely to have complications overall (22% vs 52%, p=0.015). Complications were independently more than twice as common with established inflammation with a CRP level of >150 mg/l (p<0.05).

CONCLUSIONS

A high preoperative CRP level predicts an increased rate of postoperative complication due to established inflammation and/or infection. This raises the question of whether we should be offering primary open appendicectomies to patients with a CRP level of >150 mg/l.

Reduction in gastric cancer surgical mortality over 10 years: An adverse events analysis

Background

The reduction in gastric cancer mortality is due to a reduction in incidence and of surgical mortality. This study was to examine adverse events in patients with gastric cancer dying under surgical care.

Methods

Adverse events in surgical care were prospectively audited in patients who died of gastric cancer in Scottish hospitals. A cohort retrospective study examining deaths and contributing adverse events was compared for the periods 1996–2000 and 2001–2005.

Results

Between 1996 and 2005, 1083 patients with gastric cancer died on surgical wards in Scottish hospitals. The annual number of deaths under surgical care fell significantly from an average of 128 deaths per annum in years 1996–2000 to 88 deaths per annum in 2001–2005 (p < 0.001). This occurred in parallel with the decline in gastric cancer incidence over the same period. There was an increase in the proportion of gastric cancer resections carried out in 7 major hospitals in Scotland in the second period of the study (p < 0.001). The mean number of deaths in the group of patients, who had gastric cancer resection and palliative surgery, were significantly lower in the second period of the study In addition, when all patients were considered as a group, the mean number of anaesthetic, critical care, medical management and technical surgery adverse events were significantly lower in the second study period.

Conclusion

There has been a reduction in deaths and adverse events for patients with gastric cancer under surgical care and this has been associated with surgical subspecialisation in oesophago-gastric cancer surgery.

Use of the high dependency unit, increased consultant involvement and reduction in adverse events in patients who die after colorectal cancer surgery

AIM

We prospectively audited adverse events for surgical patients with colorectal cancer who died under surgical care to test the hypothesis that increased critical care and consultant input could be associated with a reduction in adverse events.

METHOD

Patients with a diagnosis of colorectal cancer who died under surgical care in Scotland from 1996 to 2005 underwent peer review audit using established methodologies through the Scottish Audit of Surgical Mortality.

RESULTS

In the 10-year study period, 3029 patients with colorectal cancer, mean age 76 (13-105) years, died under surgical care, of whom 80% had presented as an emergency admission. Operative intervention was performed in 1557 (51%) patients of whom 1030 (34%) patients had a resection of the cancer. The annual number of patients dying after a cancer resection decreased significantly (P = 0.009). Significant decreases in adverse events were noted over time with a 67% fall in adverse events relating to critical care (P = 0.009), a 37% fall for surgical care (P = 0.04) and a significant increase in consultant anaesthetist and consultant surgeon input, but there was a 9% increase in delay as an adverse event (P = 0.006). The documented anastomotic leakage rate in patients who died increased from 8% in 1996 to 19% in 2005 (P = 0.016).

CONCLUSION

The number of patients dying with colorectal cancer after surgery has decreased in recent years. Adverse events in these patients have significantly reduced over a decade with increased consultant involvement although there is the potential for further improvement.

Control of type 1 diabetes mellitus and shift work

BACKGROUND

People with type 1 diabetes may find diabetic control more difficult when working shifts.

AIMS

To investigate the proportion of people with type 1 diabetes in employment undertaking shift work and diabetic control as assessed by glycosylated haemoglobin (HbA1c) among individuals undertaking shift work compared to those not doing so.

METHODS

A postal questionnaire sent to all those aged 16-65 attending two city hospitals for type 1 diabetes care. HbA1c results were used to assess diabetic control.

RESULTS

Twenty-two per cent (296 of 1370 eligible patients) responded. Sixty-seven (23%) respondents were involved in shift work. Shift workers had higher mean HbA1c values than non-shift workers (9.02 versus 8.35; P < 0.01).

CONCLUSIONS

Poorer control of diabetes was associated with working shifts in this study. Occupational health practitioners should be aware of this association and be able to advise on management strategies to improve diabetic control while working shifts.

Mesenteric lipoma causing small bowel perforation: a case report and review of literature

A lipoma of the small bowel mesentery is a rare pathological entity. It has been shown to rarely cause obstruction and volvulus of the small bowel. We report a case of a 72-year-old man who presented with lower abdominal pain and slightly raised inflammatory markers. Computerized tomography of the abdomen showed small bowel perforation and oedematous terminal ileum. At laparotomy the cause was found to be a mesenteric lipoma causing small bowel perforation. As far as the authors are aware, this presentation is not described in the English language literature.

Intersex (testicular oocytes) in smallmouth bass from the Potomac River and selected nearby drainages

Intersex, or the presence of characteristics of both sexes, in fishes that are normally gonochoristic has been used as an indicator of exposure to estrogenic compounds. In 2003, during health assessments conducted in response to kills and a high prevalence of skin lesions observed in smallmouth bass Micropterus dolomieu in the South Branch of the Potomac River, the presence of immature oocytes within testes was noted. To evaluate this condition, a severity index (0-4) was developed based on the distribution of oocytes within the testes. Using gonad samples collected from 2003 to 2005, the number of histologic sections needed to accurately detect the condition in mature smallmouth bass was statistically evaluated. The reliability of detection depended on the severity index and the number of sections examined. Examining five transverse sections taken along the length of the gonad resulted in a greater than 90% probability of detecting testicular oocytes when the severity index exceeded 0.5. Using the severity index we compared smallmouth bass collected at selected sites within the South Branch during three seasons in 2004. Seasonal differences in severity and prevalence were observed. The highest prevalence and severity were consistently noted during the prespawn-spawning season, when compared with the postspawn season. In 2005, smallmouth bass were collected at selected out-of-basin sites in West Virginia where fish kills and external skin lesions have not been reported, as well as at sites in the Shenandoah River, Virginia (part of the Potomac drainage), where kills and lesions occurred in 2004-2005. The prevalence of testicular oocytes is discussed in terms of human population and agricultural intensity.

Role of binding energy in Feshbach-resonant positron-molecule annihilation

Measurements of positron-on-molecule annihilation have established that positrons bind to a variety of molecules via vibrational Feshbach resonances. Data for deeply bound states in benzene and 1-chlorohexane and for positronically excited (i.e., second) bound states in alkanes are used to establish the dependence of annihilation rates on the binding energy and incident positron energy. With this dependence removed, annihilation rates for a broad class of molecules lie on a universal curve as a function of the number of molecular vibrational degrees of freedom. The implications of these results for theoretical models are discussed.

Leaving the professional tennis circuit: exploratory study of experiences and reactions from elite female athletes

In 2002, Tennis Australia commissioned a report into the experiences of elite female past players on leaving the professional tennis circuit. Australian players who were in the top 800 of the Women's Tennis Association (WTA) end of year rankings and who had left the professional circuit within the previous 15 years were asked by mail to respond to a questionnaire. The questionnaire asked players to describe their feelings about leaving the tour during the time leading up to leaving the tour to two years after retirement. The main findings of the study suggested that those who planned to leave the tour found the transition process easy, whereas those who did not plan to leave the tour found the process difficult. Most players (66%) did not regret leaving the tour, and, although the remaining players responded that they regretted leaving, none attempted a comeback. Tennis Australia has implemented strategies to assist current players on the professional tour based on the results of this study.

Evaluation of tuberculosis contact investigations in California

OBJECTIVE

To estimate the burden of tuberculosis (TB) contact investigations in California, assess outcomes and effectiveness, and identify performance gaps.

METHODS

Aggregate program management reports were used to examine contact investigations conducted for pulmonary TB cases reported between 1 July 1999 and 30 June 2000 in California. Findings were compared to national objectives, and performance gaps were identified. Costs were estimated, and effectiveness of TB case detection and prevention was assessed.

RESULTS

A total of 2032 acid-fast bacilli sputum smear-positive and sputum smear-negative/culture-positive cases was reported; 17774 contacts were elicited, and 15582 (88%) contacts were evaluated. TB disease and latent tuberculosis infection (LTBI) were diagnosed in 111 (<1%) and 4609 (30%) contacts, respectively; 1958 (43%) contacts with LTBI completed treatment. Costs of contact investigations were estimated at dollars 4.8 million; 81% of expected TB cases were detected, but only 35% of cases expected to occur within 2 years following the investigation were prevented.

CONCLUSIONS

California's performance did not meet national objectives for contact evaluation or treatment completion; improved effectiveness of contact investigations in California is needed. Although analysis of existing contact investigation surveillance data provided a macro-level view of performance gaps, expanded surveillance data are required to inform interventions.

Extramammary metastatic neoplasms in the breast: a cytomorphological study of 11 cases

The occurrence of metastatic tumours in the breast is uncommon and it is crucial for cytologists to be aware and distinguish them cytologically from primary breast tumours in fine needle aspirates. In the present retrospective study of 11 cases, over a 20-year period, we discuss the cytological features of extramammary metastatic tumours in the breast. A brief attempt has been made to discuss the past literature. The 11 metastatic tumours included four haematolymphoid neoplasms, two melanomas, two metastatic sarcomas and three metastatic carcinomas. A prior clinical diagnosis of the primary tumour was obtained in seven cases. Immunohistochemistry or histology following a cytological diagnosis confirmed all the cases. The main objective of this study was to highlight the use of cytology and at the same time caution the cytologist to be aware of the clinical/imaging findings and if necessary to utilize immunohistochemical facilities to consider/rule out the possibility of metastatic tumour in the breast.

Low vision services for vision rehabilitation in the United Kingdom

AIM

Little is known about the distribution and methods of delivery of low vision services across the United Kingdom. The purpose of this study was to determine the type and location of low vision services within the UK.

METHODS

Survey by means of a 29 point postal questionnaire, followed when necessary by a five point telephone questionnaire. All known potential providers of low vision services (n = 2539) including hospitals (n = 277), optician/optometry practices (n = 1683), social services (n = 177), voluntary groups (n = 190), specialist teachers (n = 205), and universities (n = 6) were surveyed. For each service provider, the type, magnitude, and geographical location were determined. The distribution of services across the United Kingdom and the ratio of providers to population density of people with a visual impairment were mapped using the Geographic Information System (GIS).

RESULTS

Data were obtained on 1945 (77%) service providers: 1679 (66%) responded to the postal questionnaire and 266 (11%) to the telephone questionnaire. Of all respondents, 59% (n = 1135) offer some form of help to people with a visual disability, of which 26% (n = 497) only sell magnifiers and 33% (n = 638) provide low vision services. It is estimated that in total just under 155,000 low vision consultations are offered annually, the bulk of which are provided by hospital eye departments. The distribution was geographically uneven and there appears to be scarcity in some areas.

CONCLUSION

When compared to the probable number of people with a visual impairment in the UK there are apparent inadequacies in service provision in terms of distribution, magnitude, and coordination. The results highlight a need to review current services.

Self-reported dietary habits, overall dietary quality and symptomatology of breast cancer survivors: a cross-sectional examination

Little information is available about the relationship between quality of life of women who have survived breast cancer (specifically, symptoms including those of menopause and depression) and the quality of their diet. In this cross-sectional study, 117 women with known primary breast cancer completed a self-administered food frequency questionnaire (FFQ) reflecting usual diet during the past year, a Survey of Feelings and Attitudes using the Center for Epidemiologic Studies Depression scale (CES-D) and a survey that includes menopausal symptoms among others common to women with a history of breast cancer. When women's responses to the FFQ were scored using the Healthy Eating Index (HEI), most often diets were evaluated as those that 'need improvement' with a mean total HEI score of 67.2. With regard to the CES-D scores, study women averaged 9.5, with 19 women being classified as clinically depressed. HEI and CES-D scores were inversely related (p = -0.22, p = 0.02). A negative correlation was also observed between energy-adjusted calcium intakes and CES-D scores (p = -0.19, p = 0.04). Clinical depressed women had not only lower HEI scores and calcium intakes, but also lower grain and variety scores. Comparisons to national data for disease-free women and that available for those with breast cancer suggest that our study women consumed diets low in energy and dietary variety. Diet quality may be an important factor influencing the manifestation of depressive symptoms in breast cancer survivors or conversely, poorer diet quality may be an outcome of depression.

Identification of the cellular receptor for anthrax toxin

The tripartite toxin secreted by Bacillus anthracis, the causative agent of anthrax, helps the bacterium evade the immune system and can kill the host during a systemic infection. Two components of the toxin enzymatically modify substrates within the cytosol of mammalian cells: oedema factor (OF) is an adenylate cyclase that impairs host defences through a variety of mechanisms including inhibiting phagocytosis; lethal factor (LF) is a zinc-dependent protease that cleaves mitogen-activated protein kinase kinase and causes lysis of macrophages. Protective antigen (PA), the third component, binds to a cellular receptor and mediates delivery of the enzymatic components to the cytosol. Here we describe the cloning of the human PA receptor using a genetic complementation approach. The receptor, termed ATR (anthrax toxin receptor), is a type I membrane protein with an extracellular von Willebrand factor A domain that binds directly to PA. In addition, a soluble version of this domain can protect cells from the action of the toxin.

Robotic surgical training in an academic institution

OBJECTIVE

To detail robotic procedure development and clinical applications for mitral valve, biliary, and gastric reflux operations, and to implement a multispecialty robotic surgery training curriculum for both surgeons and surgical teams.

SUMMARY BACKGROUND DATA

Remote, accurate telemanipulation of intracavitary instruments by general and cardiac surgeons is now possible. Complex technologic advancements in surgical robotics require well-designed training programs. Moreover, efficient robotic surgical procedures must be developed methodically and safely implemented clinically.

METHODS

Advanced training on robotic systems provides surgeon confidence when operating in tiny intracavitary spaces. Three-dimensional vision and articulated instrument control are essential. The authors' two da Vinci robotic systems have been dedicated to procedure development, clinical surgery, and training of surgical specialists. Their center has been the first United States site to train surgeons formally in clinical robotics.

RESULTS

Established surgeons and residents have been trained using a defined robotic surgical educational curriculum. Also, 30 multispecialty teams have been trained in robotic mechanics and electronics. Initially, robotic procedures were developed experimentally and are described. In the past year the authors have performed 52 robotic-assisted clinical operations: 18 mitral valve repairs, 20 cholecystectomies, and 14 Nissen fundoplications. These respective operations required 108, 28, and 73 minutes of robotic telemanipulation to complete. Procedure times for the last half of the abdominal operations decreased significantly, as did the knot-tying time in mitral operations. There have been no deaths and few complications. One mitral patient had postoperative bleeding.

CONCLUSION

Robotic surgery can be performed safely with excellent results. The authors have developed an effective curriculum for training teams in robotic surgery. After training, surgeons have applied these methods effectively and safely.

Roles of the C termini of alpha -, beta -, and gamma -subunits of epithelial Na+ channels (ENaC) in regulating ENaC and mediating its inhibition by cytosolic Na+

The amiloride-sensitive epithelial Na(+) channels (ENaC) in the intralobular duct cells of mouse mandibular glands are inhibited by the ubiquitin-protein ligase, Nedd4, which is activated by increased intracellular Na(+). In this study we have used whole-cell patch clamp methods in mouse mandibular duct cells to investigate the role of the C termini of the alpha-, beta-, and gamma-subunits of ENaC in mediating this inhibition. We found that peptides corresponding to the C termini of the beta- and gamma-subunits, but not the alpha-subunit, inhibited the activity of the Na(+) channels. This mechanism did not involve Nedd4 and probably resulted from the exogenous C termini interfering competitively with the protein-protein interactions that keep the channels active. In the case of the C terminus of mouse beta-ENaC, the interacting motif included betaSer(631), betaAsp(632), and betaSer(633). In the C terminus of mouse gamma-ENaC, it included gammaSer(640). Once these motifs were deleted, we were able to use the C termini of beta- and gamma-ENaC to prevent Nedd4-mediated down-regulation of Na(+) channel activity. The C terminus of the alpha-subunit, on the contrary, did not prevent Nedd4-mediated inhibition of the Na(+) channels. We conclude that mouse Nedd4 interacts with the beta- and gamma-subunits of ENaC.

Laparoscopic peritoneal lavage in staging gastric and oesophageal cancer

AIMS

Accurate staging of gastric, oesophageal and oesophagogastric cancer is essential to avoid unnecessary laparotomies in patients where only palliation is appropriate. This requires a multimodal approach utilizing endoscopy, computed tomography and laparoscopy. Previous authors have found that the presence of free peritoneal tumour cells (FPTCs) detected at laparoscopy or laparotomy confers a poorer prognosis. However, various methods of peritoneal lavage are described. The aim of this study was to evaluate the prognostic value of our technique of peritoneal lavage.

MATERIALS AND METHODS

88 staging laparoscopies with peritoneal lavage were carried out between March 1997 and February 1999 on patients eligible for attempted curative resection of a gastric, oesophageal or oesophagogastric cancer. During laparoscopy the pelvis was irrigated with 200 ml of normal saline, with 100 ml aspirated and examined cytologically. Patients were followed-up until September, 1999.

RESULTS

11 patients had FPTC-positive cytology with a median survival following laparoscopy of 122 days (95% CI 82-161) with only a single patient surviving more than one year. In the FPTC-negative group, median survival was 378 days (95% CI 256,-). Log-rank Chi(2)=16.7, P<0.001.

CONCLUSIONS

The presence of FPTCs detected by our technique is a contraindication to attempted curative resection - palliation only (medical or surgical) is appropriate.

Two functionally distinct forms of a retroviral receptor explain the nonreciprocal receptor interference among subgroups B, D, and E avian leukosis viruses

Subgroups B, D, and E avian leukosis viruses (ALV-B, -D, and -E) share the same chicken receptor, TVB(S1), a tumor necrosis factor receptor (TNFR)-related protein. These viruses, however, exhibit nonreciprocal receptor interference (NRI): cells preinfected with ALV-B or ALV-D are resistant to superinfection by viruses of all three subgroups, whereas those pre-infected by ALV-E are resistant only to superinfection by other subgroup E viruses. In this study, we investigated the basis of this phenomenon by characterizing the interaction of TVB(S1) with ALV-B Env or ALV-E Env. Sequential immunoprecipitation analysis using surface envelope immunoglobulin fusion proteins revealed the existence of two separate types of TVB(S1) that are encoded by the same cDNA clone. One form, designated the type 1 receptor, is specific for ALV-B and ALV-E. The other form, the type 2 receptor, is specific for ALV-B. We show that a protein consisting of only the first and second extracellular cysteine-rich domains of TVB(S1) is capable of forming both receptor types. However, the third extracellular cysteine-rich domain is required for efficient formation of the type 1 receptor. We also demonstrate that heterogeneous N-linked glycosylation cannot explain the difference in activities of the two receptor types. The existence of two types of TVB(S1) explains the NRI pattern between ALV-B and -E: subgroup B viruses establish receptor interference with both receptor types, whereas subgroup E viruses interfere only with the type 1 receptor, leaving the type 2 receptor available to mediate subsequent rounds of ALV-B entry. The formation of a TVB receptor type that is specific for cytopathic ALV may also have important implications for understanding how some subgroups of ALV cause cell death.

Targeting avian leukosis virus subgroup A vectors by using a TVA-VEGF bridge protein

Previously, we have demonstrated that bridge proteins comprised of avian leukosis virus (ALV) receptors fused to epidermal growth factor (EGF) can be used to selectively target retroviral vectors with ALV envelope proteins to cells expressing EGF receptors. To determine whether another type of ligand incorporated into an ALV receptor-containing bridge protein can also function to target retroviral infection, the TVA-VEGF110 bridge protein was generated. TVA-VEGF110 consists of the extracellular domain of the TVA receptor for ALV subgroup A (ALV-A), fused via a proline-rich linker peptide to a 110-amino-acid form of vascular endothelial growth factor (VEGF). This bridge protein bound specifically to its cell surface receptor, VEGFR-2, and efficiently mediated the entry of an ALV-A vector into cells. These studies indicate that ALV receptor-ligand bridge proteins may be generally useful tools for retroviral targeting approaches.

Robotic Nissen fundoplication: alternative surgical technique for the treatment of gastroesophageal reflux disease

The first robotic Nissen fundoplication using the da Vinci robotic surgical system was performed on a 56-year-old woman with a 20-year history of severe gastroesophageal reflux disease refractory to medical management. The recovery was uneventful, and follow-up continues.

Chromatographic separations as a prelude to two-dimensional electrophoresis in proteomics analysis

Current methods of proteome analysis rely almost solely on two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) followed by the excision of individual spots and protein identification using mass spectrometry (MS) and database searching. 2-D PAGE is denaturing in both dimensions and, thus, cannot indicate functional associations between individual proteins. Moreover, less abundant proteins are difficult to identify. To simplify the proteome, and explore functional associations, nondenaturing anion exchange column chromatography was used to separate a soluble protein extract from Escherichia coli. Successive fractions were then analysed using 2-D PAGE and selected spots from both the gels for the start material and the fractionated material were quantified and identified by peptide mass fingerprinting using a MALDI-TOF mass spectrometer. Enrichments of up to 13-fold were attained for individual protein spots and peptide mass fingerprints were of significantly higher quality after chromatographic separation. The marked anomalies between predicted p/and column elution position contrasted with the almost perfect correlation with migration distance on isoelectric focusing (IEF) and were explored further for basic proteins.

Effect of acutely increased left ventricular afterload on work output from the right ventricle in conscious dogs

OBJECTIVE

To determine the effect of acute increments in left ventricular afterload on the stroke work output of the right ventricle in vivo.

METHODS

After pharmacologic attenuation of autonomic reflexes, left and right ventricular pressure-volume data were obtained in 9 conscious dogs during vena caval occlusions performed before and during aortic constriction.

RESULTS

The relationship between right ventricular stroke work and end-diastolic volume during vena caval occlusion was highly linear (r = 0.97 +/- 0.02), but the slope decreased by 20% +/- 13% during aortic constriction sufficient to increase left ventricular mean ejection pressure by 25% +/- 14% (P <.05). The volume-axis intercept remained constant. Similarly, the slope of the linear relationship between right ventricular free wall regional segment work and end-diastolic segment length declined by 22% +/- 10% during aortic constriction (P <.05), without significant change in the length-axis intercept. The reduction in both global and regional right ventricular stroke work at any given preload with increased left ventricular afterload was due entirely to decreased right ventricular stroke volume and free wall shortening, because right ventricular mean ejection pressure was unchanged. Additional experiments were performed in 5 open-chest dogs to produce a greater reduction in left ventricular free wall shortening than observed with aortic constriction by transient constriction of the left circumflex coronary artery. However, this intervention had no effect on right ventricular free wall segment work output.

CONCLUSION

Increased left ventricular afterload decreases global and regional right ventricular stroke work at any given preload, a direct, negative systolic ventricular interaction.

TVB receptors for cytopathic and noncytopathic subgroups of avian leukosis viruses are functional death receptors

The identification of TVB(S3), a cellular receptor for the cytopathic subgroups B and D of avian leukosis virus (ALV-B and ALV-D), as a tumor necrosis factor receptor-related death receptor with a cytoplasmic death domain, provides a compelling argument that viral Env-receptor interactions are linked to cell death (4). However, other TVB proteins have been described that appear to have similar death domains but are cellular receptors for the noncytopathic subgroup E of ALV (ALV-E): TVB(T), a turkey subgroup E-specific ALV receptor, and TVB(S1), a chicken receptor for subgroups B, D, and E ALV. To begin to understand the role of TVB receptors in the cytopathic effects associated with infection by specific ALV subgroups, we asked whether binding of a soluble ALV-E surface envelope protein (SU) to its receptor can lead to cell death. Here we report that ALV-E SU-receptor interactions can induce apoptosis in quail or turkey cells. We also show directly that TVB(S1) and TVB(T) are functional death receptors that can trigger cell death by apoptosis via a mechanism involving their cytoplasmic death domains and activation of the caspase pathway. These data demonstrate that ALV-B and ALV-E use functional death receptors to enter cells, and it remains to be determined why only subgroups B and D viral infections lead specifically to cell death.

Retroviral entry mediated by receptor priming and low pH triggering of an envelope glycoprotein

Avian leukosis virus (ALV) has been used as a model system to understand the mechanism of pH-independent viral entry involving receptor-induced conformational changes in the viral envelope (Env) glycoprotein that lead to membrane fusion. Here, we report the unexpected finding that ALV entry depends on a critical low pH step that was overlooked when this virus was directly compared to the classical pH-dependent influenza A virus. In contrast to influenza A virus, receptor interaction plays an essential role in priming ALV Env for subsequent low pH triggering. Our results reveal a novel principle in viral entry, namely that receptor interaction can convert a pH-insensitive viral glycoprotein to a form that is responsive to low pH.

A TVA-single-chain antibody fusion protein mediates specific targeting of a subgroup A avian leukosis virus vector to cells expressing a tumor-specific form of epidermal growth factor receptor

We have previously described an approach that employs retroviral receptor-ligand bridge proteins to target retroviral vectors to specific cell types. To determine whether targeted retroviral entry can also be achieved using a retroviral receptor-single-chain antibody bridge protein, the TVA-MR1 fusion protein was generated. TVA-MR1 is comprised of the extracellular domain of the TVA receptor for subgroup A avian leukosis viruses (ALV-A), fused to the MR1 single-chain antibody that binds specifically to EGFRvIII, a tumor-specific form of the epidermal growth factor receptor. We show that TVA-MR1 binds specifically to a murine version of EGFRvIII and promotes ALV-A entry selectively into cells that express this cell surface marker. These studies demonstrate that it is possible to target retroviral vectors to specific cell types through the use of a retroviral receptor-single-chain antibody fusion protein.

Band-shaped and whorled microcystic dystrophy of the corneal epithelium

OBJECTIVE

To report the clinical, histopathologic, and electron microscopic features of band-shaped and whorled microcystic corneal epithelial dystrophy.

DESIGN

Two interventional case reports.

PARTICIPANTS

Two patients, two eyes.

INTERVENTION

The involved area of corneal epithelium was scraped from each cornea.

RESULTS

Histopathologic examination showed microscopic vacuoles in the epithelial cytoplasm in both cases. Electron microscopic examination revealed mainly empty cytoplasmic vacuoles with scant nonspecific osmophilic material. The process recurred clinically in one patient. Changes in corneal topography are documented in one patient.

CONCLUSION

Clinical findings and pathologic studies seem nearly identical to those in the original report. No pattern of systemic disorder or medication use was found. The cause of this condition remains unknown.

Influenza virus inhibits amiloride-sensitive Na+ channels in respiratory epithelia

Many pathogens causing diarrhea do so by modulating ion transport in the gut. Respiratory pathogens are similarly associated with disturbances of fluid balance in the respiratory tract, although it is not known whether they too act by altering epithelial ion transport. Here we show that influenza virus A/PR/8/34 inhibits the amiloride-sensitive Na(+) current across mouse tracheal epithelium with a half-time of about 60 min. We further show that the inhibitory effect of the influenza virus is caused by the binding of viral hemagglutinin to a cell-surface receptor, which then activates phospholipase C and protein kinase C. Given the importance of epithelial Na(+) channels in controlling the amount of fluid in the respiratory tract, we suggest that down-regulation of Na(+) channels induced by influenza virus may play a role in the fluid transport abnormalities that are associated with influenza infections.

Auditory and behavioral responses of bottlenose dolphins (Tursiops truncatus) and a beluga whale (Delphinapterus leucas) to impulsive sounds resembling distant signatures of underwater explosions

A behavioral response paradigm was used to measure masked underwater hearing thresholds in two bottlenose dolphins and one beluga whale before and after exposure to impulsive underwater sounds with waveforms resembling distant signatures of underwater explosions. An array of piezoelectric transducers was used to generate impulsive sounds with waveforms approximating those predicted from 5 or 500 kg HBX-1 charges at ranges from 1.5 to 55.6 km. At the conclusion of the study, no temporary shifts in masked-hearing thresholds (MTTSs), defined as a 6-dB or larger increase in threshold over pre-exposure levels, had been observed at the highest impulse level generated (500 kg at 1.7 km, peak pressure 70 kPa); however, disruptions of the animals' trained behaviors began to occur at exposures corresponding to 5 kg at 9.3 km and 5 kg at 1.5 km for the dolphins and 500 kg at 1.9 km for the beluga whale. These data are the first direct information regarding the effects of distant underwater explosion signatures on the hearing abilities of odontocetes.

Identification and characterization of a shared TNFR-related receptor for subgroup B, D, and E avian leukosis viruses reveal cysteine residues required specifically for subgroup E viral entry

Genetic and receptor interference data have indicated the presence of one or more cellular receptors for subgroup B, D, and E avian leukosis viruses (ALV) encoded by the s1 allele of the chicken tvb locus. Despite the prediction that these viruses use the same receptor, they exhibit a nonreciprocal receptor interference pattern: ALV-B and ALV-D can interfere with infection by all three viral subgroups, but ALV-E only interferes with infection by subgroup E viruses. We identified a tvb(s1) cDNA clone which encodes a tumor necrosis factor receptor-related receptor for ALV-B, -D, and -E. The nonreciprocal receptor interference pattern was reconstituted in transfected human 293 cells by coexpressing the cloned receptor with the envelope (Env) proteins of either ALV-B or ALV-E. This pattern of interference was also observed when soluble ALV surface (SU)-immunoglobulin fusion proteins were bound to this cellular receptor before viral challenge. These data demonstrate that viral Env-receptor interactions can account for the nonreciprocal interference between ALV subgroups B, D, and E. Furthermore, they indicate that a single chicken gene located at tvb(s1) encodes receptors for these three viral subgroups. The TVB(S1) protein differs exclusively at residue 62 from the published subgroup B- and D-specific receptor, encoded by the s3 allele of tvb. Residue 62 is a cysteine in TVB(S1) but is a serine in TVB(S3), giving TVB(S1) an even number of cysteines in the extracellular domain. We present evidence for a disulfide bond requirement in TVB(S1) for ALV-E infection but not for ALV-B infection. Thus, ALV-B and ALV-E interact in fundamentally different ways with this shared receptor, a finding that may account for the observed biological differences between these two ALV subgroups.

Response of the intact canine left ventricle to increased afterload and increased coronary perfusion pressure in the presence of coronary flow autoregulation

BACKGROUND

Increased left ventricular (LV) contractile force or oxygen consumption has been documented with increased coronary arterial pressure (CAP) and flow (Gregg phenomenon). We investigated whether the increase in contractile force with increased LV afterload might be mediated by the concomitant increase in CAP when coronary autoregulation is intact.

METHODS AND RESULTS

The LV of 6 autonomically blocked open-chest dogs was perfused through the left main coronary artery by a cannula with a side gate to the aortic root. With the gate open, CAP increased from 77+/-20 to 93+/-20 mm Hg (P<0.05) with aortic constriction (AC). With the gate closed, CAP was maintained at a constant level of 100 mm Hg. A small reduction in the slope of the preload recruitable stroke work (PRSW) relationship was observed with AC, but this response was not altered by the coronary perfusion gate position. The end-systolic pressure-volume (ESPV) relationship shifted upward significantly with AC (P<0.001), but this shift was not greater with open-gate perfusion than with closed-gate perfusion. Furthermore, with coronary autoregulation intact, wide changes in CAP (between 60 and 180 mm Hg, n=5) did not alter either the PRSW or ESPV relationship. In contrast, when autoregulation was abolished with intracoronary adenosine (n=6), both indexes of contractility increased progressively with increased CAP.

CONCLUSIONS

The concomitant increase in CAP with increased afterload in the intact canine LV does not contribute to the afterload-induced increase in contractile force. Coronary perfusion pressure per se does not influence LV contractile function. Coronary perfusion pressure influences contractility only when coronary flow changes.

Retroviral vectors preloaded with a viral receptor-ligand bridge protein are targeted to specific cell types

Successful targeting methods represent a major hurdle to the use of retroviral vectors in cell-specific gene-delivery applications. We recently described an approach for retroviral targeting with a retroviral receptor-ligand bridge protein that was bound to the cognate cell-surface ligand receptors before viral challenge. We now report a significant improvement made to this viral targeting method by using a related bridge protein, designated TVB-EGF, comprised of the extracellular domain of the TVB receptor for subgroup B avian leukosis virus fused to epidermal growth factor (EGF). The most important activity of TVB-EGF was that it allowed specific viral entry when preloaded onto virions. Furthermore, virions preloaded with TVB-EGF were thermostable and could be produced directly from virus- packaging cells. These data suggest an approach for targeting retroviral vectors to specific cell types by using virions preloaded with a retroviral receptor-ligand bridge protein and indicate that these types of bridge proteins may be useful reagents for studying the normal mechanism of retroviral entry.

Na(+)-H(+) exchange in salivary secretory cells is controlled by an intracellular Na(+) receptor

It recently has been shown that epithelial Na(+) channels are controlled by a receptor for intracellular Na(+), a G protein (G(o)), and a ubiquitin-protein ligase (Nedd4). Furthermore, mutations in the epithelial Na(+) channel that underlie the autosomal dominant form of hypertension known as Liddle's syndrome inhibit feedback control of Na(+) channels by intracellular Na(+). Because all epithelia, including those such as secretory epithelia, which do not express Na(+) channels, need to maintain a stable cytosolic Na(+) concentration ([Na(+)](i)) despite fluctuating rates of transepithelial Na(+) transport, these discoveries raise the question of whether other Na(+) transporting systems in epithelia also may be regulated by this feedback pathway. Here we show in mouse mandibular secretory (endpiece) cells that the Na(+)-H(+) exchanger, NHE1, which provides a major pathway for Na(+) transport in salivary secretory cells, is inhibited by raised [Na(+)](i) acting via a Na(+) receptor and G(o). This inhibition involves ubiquitination, but does not involve the ubiquitin protein ligase, Nedd4. We conclude that control of membrane transport systems by intracellular Na(+) receptors may provide a general mechanism for regulating intracellular Na(+) concentration.

Street talk: knowledge and attitudes about tuberculosis and tuberculosis control among homeless adults

OBJECTIVES

To measure knowledge and perceived susceptibility to tuberculosis among homeless adults in San Francisco and attitudes toward control measures used to improve adherence to treatment for tuberculosis.

DESIGN

A cross-sectional survey via interview of homeless shelter residents was done at five shelters.

RESULTS

Of 292 persons interviewed, 21.6% reported a positive skin test, and 57.1% of the positives had received preventive therapy. Over 60% had misconceptions about transmission, in particular confusion with transmission of the human immunodeficiency virus (HIV). Knowledge of skin testing procedures and symptoms was generally good, and most reported health care providers as the main source of information. Over half reported concern about catching tuberculosis and over 80% favored controls to ensure adherence, in particular directly observed therapy. Higher TB knowledge score (P = 0.0155) and male sex (P = 0.0357) were associated with a favorable attitude toward directly observed therapy.

CONCLUSIONS

Health care providers should expand educational messages beyond skin testing. Greater knowledge about tuberculosis may increase acceptance of control measures. Targeted education plus social norms favoring completion of therapy may improve screening and treatment outcomes in this population.