A toxic environment selects for specialist microbiome in poison frogs

Shifts in microbiome community composition can have large effects on host health. It is therefore important to understand how perturbations, like those caused by the introduction of exogenous chemicals, modulate microbiome community composition. In poison frogs within the family Dendrobatidae, the skin microbiome is exposed to the alkaloids that the frogs sequester from their diet and use for defense. Given the demonstrated antimicrobial effects of these poison frog alkaloids, these compounds may be structuring the skin microbial community. To test this, we first characterized microbial communities from chemically defended and closely related non-defended frogs from Ecuador. Then we conducted a laboratory experiment to monitor the effect of the alkaloid decahydroquinoline (DHQ) on the microbiome of a single frog species. In both the field and lab experiments, we found that alkaloid-exposed microbiomes are more species rich and phylogenetically diverse, with an increase in rare taxa. To better understand the strain-specific behavior in response to alkaloids, we cultured microbial strains from poison frog skin and found the majority of strains exhibited either enhanced growth or were not impacted by the addition of DHQ. Additionally, stable isotope tracing coupled to nanoSIMS suggests that some of these strains are able to metabolize DHQ. Taken together, these data suggest that poison frog chemical defenses open new niches for skin-associated microbes with specific adaptations, including the likely metabolism of alkaloids, that enable their survival in this toxic environment. This work helps expand our understanding of how exposure to exogenous compounds like alkaloids can impact host microbiomes.

Implementing Home-Based Clinical Research for Caregivers and Persons with Stroke: Lessons Learned

Conducting research in the home environment presents challenges related to setting, study participants, methods, and researchers. Researchers should be aware of potential challenges to ensure rigor and improve planning for future studies. This paper describes difficulties experienced and lessons learned when conducting a two-group, randomized pilot study (n = 32) of a web-based intervention (Carepartner and Constraint-Induced Therapy [CARE-CITE]) designed to foster positive carepartner engagement in home-based activities to improve upper extremity function in persons with stroke. Challenges and issues included: 1) recruitment and referral, 2) data collection in the home setting, 3) participants' understanding of the rationale for adhering to constraint-induced movement therapy principles (wearing mitt on the less-affected limb), 4) tracking adherence of upper extremity practice time, 5) participant-driven goal setting, 6) potentially unsafe participant practice activities, 7) home visit safety, 8) encouraging versus controlling-using autonomy support, 9) participant needs beyond study scope, and 10) ethical safeguards for addressing depressive symptoms. Researchers can incorporate suggested strategies to support methodological rigor and facilitate interventions engaging carepartners in the rehabilitation process when planning for research in the home environment.

Abstract LB560: Engineering genetically-encoded synthetic biomarkers for breath-based cancer detection

Background: Breath analysis holds great promise for rapid and noninvasive early cancer detection. However, clinical implementation of endogenous volatile organic compound (VOC) signatures in breath is limited by low signal from nascent tumors and high background expression by nonmalignant tissues. By engineering tumors to express synthetic reporters that are not naturally produced in the human body, background signal from healthy tissues can be minimized, thereby maximizing sensitivity and specificity for tumor detection. Humans and plants share a common cholesterol biosynthesis (mevalonate) pathway, but in plants this pathway also generates volatile secondary metabolites (e.g. that attract pollinators). We therefore hypothesized that cancer cells could be coaxed to produce plant VOCs by genetically introducing the appropriate plant enzymes, and that these VOCs would be detectable in the breath as unique biomarkers of cancer.

Aims: 1) To express the citrus VOC, limonene, in a cultured human cancer cell line; 2) To determine the smallest tumor size at which exhaled limonene can be detected in mice implanted with limonene-expressing tumor cells.

Methods: HeLa cervical cancer cells were stably transfected with DNA vectors encoding limonene synthase (LS) alone or in combination with a truncated version of HMG-CoA reductase (HMGR), a key regulatory enzyme of the mevalonate pathway. Truncation of HMGR (tHMGR) by deletion of its regulatory domain renders it insensitive to feedback inhibition, augmenting flux through the mevalonate pathway and increasing limonene precursors. Cell culture headspace was analyzed using solid phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS), confirming the presence of limonene. A xenograft murine tumor model was created by subcutaneously implanting HeLa-LS, HeLa-LS-tHMGR, or untransfected control HeLa cells in both flanks of 10-week-old athymic nude mice. For weekly VOC measurements, mice (n = 12) were placed in 1-liter chambers with continuous flow of highly pure air, and VOCs were collected using Tenax sorbent tubes, which were subsequently analyzed by GC-MS.

Results: Limonene production in HeLa-LS-tHMGR cells was double that of HeLa-LS cells (11.0 vs. 5.6 fg/cell/day) with LODs of 107,000 and 360,000 cells, respectively, and was undetectable in untransfected HeLa cells. In xenograft mice, tumor detection improved proportionally with breath sampling time: a 10-fold increase in sampling duration resulted in 9.4-fold greater limonene production (94 ng vs. 10 ng), and dynamic headspace sampling was ~100-fold more sensitive than static sampling. Importantly, limonene was a sensitive volatile reporter, permitting detection of tumors as small as 5 mm, and increased linearly with tumor size (R2 = 0.97), demonstrating strong utility for monitoring tumor progression. Pharmacokinetic modeling of tumor-derived limonene predicts detection of tumors as small as 7 mm in humans, equivalent to the detection limit of PET imaging, yet far more economical. In future work, this strategy will be incorporated into an inhalable nonviral vector formulation with a tumor-activatable promoter (e.g. survivin) for safe, non-invasive in vivo gene delivery and tumor-specific expression of limonene for breath-based early detection of non-small cell lung cancer.

Citation Format: Ophir Vermesh, Aloma D'Souza, Israt Alam, Mirwais Wardak, Theresa McLaughlin, Fadi El Rami, Ataya Sathirachinda, John Bell, Sharon Pitteri, Michelle James, Sharon Hori, Eric Gross, Sanjiv Gambhir. Engineering genetically-encoded synthetic biomarkers for breath-based cancer detection [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB560.

Seroprevalence of SARS-CoV-2 antibodies, associated epidemiological factors and antibody kinetics among healthcare workers in Connecticut

BACKGROUND

Healthcare workers (HCWs) are at the front line of the ongoing coronavirus 2019 (COVID-19) pandemic. Comprehensive evaluation of the seroprevalence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) among HCWs in a large healthcare system could help to identify the impact of epidemiological factors and the presence of symptoms on the immune response to the infection over time.

AIM

To determine the seroprevalence of SARS-CoV-2-specific antibodies among HCWs, identify associated epidemiological factors and study antibody kinetics.

METHODS

A longitudinal evaluation of the seroprevalence and epidemiology of SARS-CoV-2-specific antibodies was undertaken in approximately 30,000 HCWs in the largest healthcare system in Connecticut, USA.

FINDINGS

At baseline, the prevalence of SARS-CoV-2 antibody among 6863 HCWs was 6.3% [95% confidence interval (CI) 5.7-6.9%], and was highest among patient care support (16.7%), medical assistants (9.1%) and nurses (8.2%), and lower for physicians (3.8%) and advanced practice providers (4.5%). Seroprevalence was significantly higher among African Americans [odds ratio (OR) 3.26 compared with Caucasians, 95% CI 1.77-5.99], in participants with at least one symptom of COVID-19 (OR 3.00, 95% CI 1.92-4.68), and in those reporting prior quarantine (OR 3.83, 95% CI 2.57-5.70). No symptoms were reported in 24% of seropositive participants. Among the 47% of participants who returned for a follow-up serological test, the seroreversion rate was 39.5% and the seroconversion rate was 2.2%. The incidence of re-infection in the seropositive group was zero.

CONCLUSION

Although there is a decline in the immunoglobulin G antibody signal over time, 60.5% of seropositive HCWs had maintained their seroconversion status after a median of 5.5 months.

Understanding the Scientific Basis of Post-traumatic Stress Disorder (PTSD): Precision Behavioral Management Overrides Stigmatization

Post-traumatic stress disorder (PTSD) is a severe polygenic disorder triggered by environmental factors. Many polymorphic genes, particularly the genetic determinants of hypodopaminergia (low dopamine function), associate with a predisposition to PTSD as well as substance use disorder. Support from the National Institutes of Health for neuroimaging research and molecular, genetic applied technologies has improved understanding of brain reward circuitry functions that have inspired the development of new innovative approaches to their early diagnosis and treatment of some PTSD symptomatology and addiction. This review presents psychosocial and genetic evidence that vulnerability or resilience to PTSD can theoretically be impacted by dopamine regulation. From a neuroscience perspective, dopamine is widely accepted as a major neurotransmitter. Questions about how to modulate dopamine clinically in order to treat and prevent PTSD and other types of reward deficiency disorders remain. Identification of genetic variations associated with the relevant genotype-phenotype relationships can be characterized using the Genetic Addiction Risk Score (GARS®) and psychosocial tools. Development of an advanced genetic panel is under study and will be based on a new array of genes linked to PTSD. However, for now, the recommendation is that enlistees for military duty be given the opportunity to voluntarily pre-test for risk of PTSD with GARS, before exposure to environmental triggers or upon return from deployment as part of PTSD management. Dopamine homeostasis may be achieved via customization of neuronutrient supplementation "Precision Behavioral Management" (PBM™) based on GARS test values and other pro-dopamine regulation interventions like exercise, mindfulness, biosensor tracking, and meditation.

Dietary weight loss in insulin-resistant non-obese humans: Metabolic benefits and relationship to adipose cell size

BACKGROUND AND AIMS

Overweight and obesity increase risk for diabetes and cardiovascular disease, largely through development of insulin resistance. Benefits of dietary weight loss are documented for obese individuals with insulin resistance. Similar benefits have not been shown in overweight individuals. We sought to quantify whether dietary weight loss improves metabolic risk profile in overweight insulin-resistant individuals, and evaluated potential mediators between weight loss and metabolic response.

METHODS AND RESULTS

Healthy volunteers with BMI 25-29.9 kg/m2 underwent detailed metabolic phenotyping including insulin-mediated-glucose disposal, fasting/daylong glucose, insulin, triglycerides, FFA, and cholesterol. Subcutaneous fat biopsies were performed for measurement of adipose cell size. After 14 weeks of hypocaloric diet and 2 weeks of weight maintenance, cardiometabolic measures and biopsies were repeated. Changes in weight, % body fat, waist circumference, adipose cell size and FFA were evaluated as predictors of change in insulin resistance. Weight loss (4.3 kg) yielded significant improvements in insulin resistance and all cardiovascular risk markers except glucose, HDL-C, and LDL-C. Improvement in insulin sensitivity was greater among those with <2 vs >2 cardiovascular risk factors at baseline. Decrease in adipose cell size and waist circumference, but not weight or body fat, independently predicted improvement in insulin resistance.

CONCLUSIONS

Weight loss yields metabolic health benefits in insulin-resistant overweight adults, even in the absence of classic cardiovascular risk factors. Weight loss-related improvement in insulin sensitivity may be mediated through changes in adipose cell size and/or central distribution of body fat. The insulin-resistant subgroup of overweight individuals should be identified and targeted for dietary weight loss.

CLINICAL TRIALS IDENTIFIER

NCT00186459.

Insurance Companies Fighting the Peer Review Empire without any Validity: the Case for Addiction and Pain Modalities in the face of an American Drug Epidemic

The United States are amid an opioid overdose epidemic; we are challenged to provide non-addicting/non-pharmacological alternatives to assist in pain attenuation. There are proven strategies available to manage chronic pain effectively without opioids. Utilization review providers for insurance companies often ignore medicine based scientific peer-reviewed studies that warn against the chronic use of opioid medications, as well as the lack of evidence to support long-term use of opioids for pain. This paradigm must change if we are to indeed change the drug-embracing culture in American chronic pain management. A barrier to treatment is pushback on the part of insurance companies especially as it relates to fighting against pain relief alternatives compared to classical analgesic agents. Pain specialists in the U.S., are compelled to find alternative solutions to help pain victims without promoting unwanted tolerance to analgesics and subsequent biological induction of the "addictive brain." It is noteworthy that reward center of the brain plays a crucial role in the modulation of nociception, and that adaptations in dopaminergic circuitry may affect several sensory and affective components of chronic pain syndromes. Possibly knowing a patient's genetic addiction risk score (GARS™) could eliminate guessing as it relates to becoming addicted.

Safety and efficacy of pasireotide in dumping syndrome-results from a phase 2, multicentre study

BACKGROUND

Dumping syndrome is a prevalent complication of oesophageal and gastric surgery characterised by early (postprandial tachycardia) and late (hypoglycaemia) postprandial symptoms.

AIM

To evaluate efficacy and safety of the somatostatin analogue, pasireotide in patients with dumping syndrome after bariatric or upper gastrointestinal cancer surgery.

METHODS

A single-arm, open-label, multicentre, intrapatient dose-escalation, phase 2 study with 4 phases: screening, 3-month SC (subcutaneous), 3-month IM (intramuscular) and 6-month optional extension IM phase. Primary endpoint was the proportion of patients without hypoglycaemia (plasma glucose <3.3 mmol/L [60 mg/dL] during an oral glucose tolerance test, OGTT) at the end of 3-month SC phase. A ≥50% response rate was considered clinically relevant.

RESULTS

Forty-three patients with late dumping were enrolled; 33 completed the 3-month SC phase and 23 completed the 12-month study. The proportion of patients without hypoglycaemia at month 3 (primary endpoint) was 60.5% (26 of 43; 95% confidence interval, 44.4%-75.0%). Improvement in quality of life was observed during SC phase, which was maintained in the IM phase. The proportion of patients with a rise in pulse rate of ≥10 beats/min during OGTT reduced from baseline (60.5%) to month 3 (18.6%) and month 12 (27.3%). Overall (month 0-12), the most frequent (>20% of patients) adverse events were headache (34.9%); diarrhoea, hypoglycaemia (27.9% each); fatigue, nausea (23.3% each); and abdominal pain (20.9%).

CONCLUSION

These results suggest that pasireotide is a promising option in patients with dumping syndrome after bariatric or upper gastrointestinal cancer surgery.

Discovery of Triazole CYP11B2 Inhibitors with in Vivo Activity in Rhesus Monkeys

Hit-to-lead efforts resulted in the discovery of compound 19, a potent CYP11B2 inhibitor that displays high selectivity vs related CYPs, good pharmacokinetic properties in rat and rhesus, and lead-like physical properties. In a rhesus pharmacodynamic model, compound 19 displays robust, dose-dependent aldosterone lowering efficacy, with no apparent effect on cortisol levels.

Discovery of Benzimidazole CYP11B2 Inhibitors with in Vivo Activity in Rhesus Monkeys

We report the discovery of a benzimidazole series of CYP11B2 inhibitors. Hit-to-lead and lead optimization studies identified compounds such as 32, which displays potent CYP11B2 inhibition, high selectivity versus related CYP targets, and good pharmacokinetic properties in rat and rhesus. In a rhesus pharmacodynamic model, 32 produces dose-dependent aldosterone lowering efficacy, with no apparent effect on cortisol levels.

Burden of corticosteroid use in patients with systemic lupus erythematosus: results from a Delphi panel

Corticosteroid-related adverse events (AEs) are commonly reported in systemic lupus erythematosus (SLE), but are often under-represented in claims data. The most common corticosteroid-related AEs are not necessarily the most costly. The present study aimed to examine corticosteroid-related AE rates and identify the associated cost consequences in patients with SLE from the perspective of rheumatologists treating SLE in the United States (US). A modified Delphi process and RAND Appropriateness Method was used to estimate corticosteroid-related AEs and costs based on data from SLE-treating US rheumatologists and estimates from alternative sources. The panel (n=10) participated in two web-based questionnaires, covering disease severity, corticosteroid use, corticosteroid-related AEs, and resource utilization associated with treatment of the AEs. Eight members of the panel then participated in a guided discussion by interactive teleconference, in which the costs associated with specific corticosteroid-related AEs were also discussed. Consensus was achieved in the teleconference when a single response category (consensus values from 1 to 4 [4=strongly agree, 1=strongly disagree]) accounted for ≥80% of responses. Thirteen consensus statements were developed following two Delphi rounds. Costs were estimated for eight corticosteroid-associated AEs from the panel of rheumatologists. In the patients with SLE treated by these physicians, 41.5% were considered to have mild disease, 36.5% moderate disease, and 22.0% severe disease. The number of specialist visits, corticosteroid use, and corticosteroid dose increased with disease severity. The estimated rates of all AEs (except for cataracts) were at least doubled in patients receiving corticosteroid doses>20 mg/day compared with ≤20 mg/day. The highest estimated mean total costs of an event (for the required treatment duration for one patient) were for avascular necrosis ($14,460) and serious infection ($11,660). The costs of more common AEs, such as osteoporosis, obesity, diabetes, and fractures, ranged from $1190 to $8220. Ten rheumatologists concluded that as disease severity increases, corticosteroid doses increased. Greater utilization of resources is needed to manage patients and corticosteroid-related AEs.

Subcutaneous adipose cell size and distribution: relationship to insulin resistance and body fat

OBJECTIVE

Metabolic heterogeneity among obese individuals may be attributable to differences in adipose cell size. We sought to clarify this by quantifying adipose cell size distribution, body fat, and insulin-mediated glucose uptake in overweight to moderately-obese individuals.

METHODS

A total of 148 healthy nondiabetic subjects with BMI 25-38 kg/m2 underwent subcutaneous adipose tissue biopsies and quantification of insulin-mediated glucose uptake with steady-state plasma glucose (SSPG) concentrations during the modified insulin suppression test. Cell size distributions were obtained with Beckman Coulter Multisizer. Primary endpoints included % small adipose cells and diameter of large adipose cells. Cell-size and metabolic parameters were compared by regression for the whole group, according to insulin-resistant (IR) and insulin-sensitive (IS) subgroups, and by body fat quintile.

RESULTS

Both large and small adipose cells were present in nearly equal proportions. Percent small cells was associated with SSPG (r = 0.26, P = 0.003). Compared to BMI-matched IS individuals, IR counterparts demonstrated fewer, but larger large adipose cells, and a greater proportion of small-to-large adipose cells. Diameter of the large adipose cells was associated with % body fat (r = 0.26, P = 0.014), female sex (r = 0.21, P = 0.036), and SSPG (r = 0.20, P = 0.012). In the highest versus lowest % body fat quintile, adipose cell size increased by only 7%, whereas adipose cell number increased by 74%.

CONCLUSIONS

Recruitment of adipose cells is required for expansion of body fat mass beyond BMI of 25 kg/m2 . Insulin resistance is associated with accumulation of small adipose cells and enlargement of large adipose cells. These data support the notion that impaired adipogenesis may underlie insulin resistance.

Measurement of apo(a) kinetics in human subjects using a microfluidic device with tandem mass spectrometry

RATIONALE

Apolipoprotein(a) [apo(a)] is the defining protein component of lipoprotein(a) [Lp(a)], an independent risk factor for cardiovascular disease. The regulation of Lp(a) levels in blood is poorly understood in part due to technical challenges in measuring Lp(a) kinetics. Improvements in the ability to readily and reliably measure the kinetics of apo(a) using a stable isotope labeled tracer is expected to facilitate studies of the role of Lp(a) in cardiovascular disease. Since investigators typically determine the isotopic labeling of protein-bound amino acids following acid-catalyzed hydrolysis of a protein of interest [e.g., apo(a)], studies of protein synthesis require extensive protein purification which limits throughput and often requires large sample volumes. We aimed to develop a rapid and efficient method for studying apo(a) kinetics that is suitable for use in studies involving human subjects.

METHODS

Microfluidic device and tandem mass spectrometry were used to quantify the incorporation of [(2)H3]-leucine tracer into protein-derived peptides.

RESULTS

We demonstrated that it is feasible to quantify the incorporation of [(2)H3]-leucine tracer into a proteolytic peptide from the non-kringle repeat region of apo(a) in human subjects. Specific attention was directed toward optimizing the multiple reaction monitoring (MRM) transitions, mass spectrometer settings, and chromatography (i.e., critical parameters that affect the sensitivity and reproducibility of isotopic enrichment measurements). The results demonstrated significant advantages with the use of a microfluidic device technology for studying apo(a) kinetics, including enhanced sensitivity relative to conventional micro-flow chromatography, a virtually drift-free elution profile, and a stable and robust electrospray.

CONCLUSIONS

The technological advances described herein enabled the implementation of a novel method for studying the kinetics of apo(a) in human subjects infused with [(2)H3]-leucine.

Metabolic heterogeneity of obesity: role of adipose tissue

Obesity is not synonymous with insulin resistance. Why some but not all individuals develop insulin resistance with weight excess is not clear, but a number of plausible hypotheses with ample support now exist. This article reviews regional fat distribution, inflammation, lipotoxicity/ectopic fat and impaired adipogenesis as leading theories as to why excess body weight has the potential to promote insulin resistance.

Quantifying apoprotein synthesis in rodents: coupling LC-MS/MS analyses with the administration of labeled water

Stable isotope tracer studies of apoprotein flux in rodent models present difficulties as they require working with small volumes of plasma. We demonstrate the ability to measure apoprotein flux by administering either (2)H- or (18)O-labeled water to mice and then subjecting samples to LC-MS/MS analyses; we were able to simultaneously determine the labeling of several proteolytic peptides representing multiple apoproteins. Consistent with relative differences reported in the literature regarding apoprotein flux in humans, we found that the fractional synthetic rate of apoB is greater than apoA1 in mice. In addition, the method is suitable for quantifying acute changes in protein flux: we observed a stimulation of apoB production in mice following an intravenous injection of Intralipid and a decrease in apoB production in mice treated with an inhibitor of microsomal triglyceride transfer protein. In summary, we demonstrate a high-throughput method for studying apoprotein kinetics in rodent models. Although notable differences exist between lipoprotein profiles that are observed in rodents and humans, we expect that the method reported here has merit in studies of dyslipidemia as i) rodent models can be used to probe target engagement in cases where one aims to modulate apoprotein production and ii) the approach should be adaptable to studies in humans.

Variation of health-care resource utilization according to GERD-associated complications

Complications associated with gastroesophageal reflux disease (GERD) can include esophageal stricture, Barrett's esophagus, gastrointestinal hemorrhage, and extraesophageal symptoms. The impact of GERD-associated complications on health-care utilization deserves further evaluation. We identified commercial enrollees 18-75 years old with claims for GERD (International Classification of Diseases, Ninth Revision, Clinical Modification Codes: 530.81 or 530.11) and subsequent usage of proton pump inhibitors from 01/01/05 to 06/30/09. The initial GERD diagnosis date was designated as the index date, and patients were studied for 6 months preindex and postindex. Eligible patients were subsequently stratified based on medical claims for GERD-associated complications as follows: stage A (GERD diagnosis, no other symptoms), stage B (GERD + extraesophageal symptoms), stage C (GERD + Barrett's esophagus), stage D (GERD + esophageal stricture), and stage E (GERD + iron-deficiency anemia or acute upper gastrointestinal hemorrhage). Patient characteristics, health-care utilization, and costs were compared between stage A and each stage with complicated GERD (B-D). Of the 174,597 patients who were eligible for analysis, 74% were classified as stage A, 20% stage B, 1% stage C, 2% stage D, and 3% stage E. Relative to stage A, patients in stages C, D, and E were significantly more likely to visit a gastroenterologist (13% vs. 68%, 71%, and 38%, respectively) and had higher rates of esophageal ulcers (0.3% vs. 8%, 5%, and 3%, respectively) and Nissen fundoplication (0.05% vs. 0.6%, 0.3%, and 0.2%, respectively). Six-month GERD-related costs ranged from $615/patient (stage A) to $1714/patient (stage D); all-cause costs ranged from $4195/patient (stage A) to $11,340/patient (stage E). Compared with stage A, all other cohorts had significantly higher all-cause and GERD-related costs (P < 0.0001 for all comparisons). While patients with more severe GERD represented a relatively small portion of the GERD cohort, they demonstrated significantly greater health-care costs and overall utilization than patients with uncomplicated GERD.

P5-20-01: Patient Valuation of Reduced Risk of Side Effects during Treatment for Metastatic Breast Cancer

Background

Chemotherapy treatment for metastatic breast cancer (MBC) has shown significant benefits in survival for breast cancer patients. However, chemotherapy is associated with several side effects that have a significant impact on patients’ quality of life. The objective of this analysis was to quantify the value patients with MBC place on reduced risk of treatment side effects.

Methods: A willingness to pay (WTP) survey was developed to assess metastatic breast cancer patients’ willingness to pay for a reduction in the risk of breast cancer treatment side effects. The survey assessed patients’ WTP for a 25%, 50% and 100% reduction in the risk of all side effects. Patients were also asked to select the side effect they would pay the most to avoid. Additionally, the survey collected demographic information such as treatment regimen, age, race/ethnicity, region, employment status, and insurance type.

Results: The survey was completed by 202 metastatic breast cancer patients. Most survey respondents were white (94%), married (62%), and over the age of 51 (78%). Most patients were covered by private insurance (67%) or Medicare (24%). Of the 58% of respondents who remembered paying out of pocket for their last treatment, the average out of pocket payment was $459. Survey respondents were willing to pay an extra $1,886, $3,837 and $7,794 for a 25%, 50% and 100% reduction in the risk of all side effects, respectively. Hair loss (28%), pain (17%) and nausea (15%) were selected most often as the side effect respondents would pay the most to avoid.

Discussion: Chemotherapy for MBC is associated with several adverse events that patients would like to avoid or reduce such as hair loss, pain, nausea and neutropenia. This analysis demonstrates patients with MBC place a significant value on reducing the risk of side effects and are willing to pay 4.2 times for a treatment devoid of side effects as compared to a treatment with a 25% reduction in the risk of treatment side effects.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-20-01.

Validation of human ApoB and ApoAI immunoturbidity assays for non-human primate dyslipidemia and atherosclerosis research

Emerging evidence suggests apolipoprotein B (apoB) and apolipoprotein AI (apoAI) are strong risk predictors for atherosclerosis. Non-human primates (NHP), including rhesus monkeys, cynomolgus monkeys, and African green monkeys, are important preclinical species for studying dyslipidemia and atherosclerosis as they more closely resemble humans in lipid metabolism and disease physiology compared to lower species such as rodents. However, no commercial assays are currently available for measuring apoB and apoAI in NHP. We therefore evaluated analytical methods for routinely measuring apoB and apoAI in our NHP dyslipidemia and atherosclerosis research. Since NHP apoB and apoAI sequences are likely highly similar to human, we focused on the clinically validated and widely utilized human apoB and apoAI immunoturbidity assays. We carried out technical validation of these assays with NHP samples and leveraged orthogonal technical platforms including mass spectrometry, independent ELISA assay, and absolute quantitation via SDS-PAGE for further characterization. Analysis of purified lipoproteins demonstrated that the immunoturbidity assays detect NHP apoAI and apoB, with good dilution linearity and spike recovery from NHP plasma. Orthogonal studies showed apoAI correlated with protein concentration and apoB levels correlated with LC/MS and an independent ELISA. NHP samples from a drug treatment study were analyzed with the immunoturbidity assays and levels of apoB and apoAI fit our understanding of biology and expectations from literature. These studies serve as important technical and biological validation of the immunoturbidity assays for NHP samples, and demonstrate that these assays provide a high-throughput, fully automated analytical platform for NHP samples. Our studies pave the way for future translational research in NHP for developing therapies for treating dyslipidemia and atherosclerosis.

Assessment of potential measures in models of progression in Alzheimer disease

BACKGROUND

In estimating the potential benefits of treatment, it is often necessary to extrapolate beyond clinical trial results using economic modeling. Previous attempts in Alzheimer disease (AD) were primarily based on the Mini-Mental State Examination (MMSE) due to its widespread use. These models were criticized as not accurately reflecting the total impact of the disease, providing untrustworthy estimates of treatment benefit. We compared 3 alternatives to the MMSE with respect to bridging between clinical outcomes needed for regulatory approval and economic and quality of life (QOL) outcomes important to reimbursement agencies.

METHODS

The MMSE, Disability Assessment in Dementia (DAD) scale, Clinical Dementia Rating (CDR) scale, and Dependence Scale (DS) were compared in their ability to explain variation in cognitive, functional, and behavioral measures as well as economic and QOL outcomes using univariate (Pearson correlations) and multivariate (linear regression) analyses of data from research sites in the United States and Europe.

RESULTS

Subjects with mild to moderate AD (n = 196; mean 75.9 years; 56% female) were evaluated. The DS, DAD, and CDR were moderately correlated with the MMSE (Pearson correlations, range 0.54-0.58) but performed better (higher adjusted R(2)) than the MMSE in explaining variations in subject behavior, QOL, and health status. The DS and DAD performed better in explaining variation in medical costs, caregiver QOL, and caregiver time.

CONCLUSIONS

Measures of function (DAD) or dependence on others (DS), or global measures (CDR), appear to be better candidates than the MMSE for modeling AD progression.

Novel approaches to incorporating pharmacoeconomic studies into phase III clinical trials for Alzheimer's disease

The societal and individual costs of Alzheimer's disease are significant, worldwide. As the world ages, these costs are increasing rapidly, while health systems face finite budgets. As a result, many regulators and payers will require or at least consider phase III cost-effectiveness data (in addition to safety and efficacy data) for drug approval and reimbursement, increasing the risks and costs of drug development. Incorporating pharmacoeconomic studies in phase III clinical trials for Alzheimer's disease presents a number of challenges. We propose several specific suggestions to improve the design of pharmacoeconomic studies in phase III clinical trials. We propose that acute episodes of care are key outcome measures for pharmacoeconomic studies. To improve the possibility of detecting a pharmacoeconomic impact in phase III, we suggest several strategies including; study designs for enrichment of pharmacoeconomic outcomes that include co-morbidity of patients; reducing variability of care that can affect pharmacoeconomic outcomes through standardized care management; employing administrative claims data to better capture meaningful pharmacoeconomic data; and extending clinical trials in open label follow-up periods in which pharmacoeconomic data are captured electronically by administrative claims. Specific aspects of power analysis for pharmacoeconomic studies are presented. The particular pharmacoeconomic challenges caused by the use of biomarkers in clinical trials, the increasing use of multinational studies, and the pharmacoeconomic challenges presented by biologicals in development for Alzheimer's disease are discussed. In summary, since we are entering an era in which pharmacoeconomic studies will be essential in drug development for supporting regulatory approval, payor reimbursement and integration of new therapies into clinical care, we must consider the design and incorporation of pharmacoeconomic studies in phase III clinical trials more seriously and more creatively.

Reducing and measuring inappropriate verbalizations in a token classroom

A procedure was employed that enabled a teacher to bring inappropriate verbalizations under control in a classroom of approximately 25 fifth- and sixth-grade students. Contingent point loss for inappropriate verbalizations was correlated with a low but steady rate of such verbalizations. Point gain contingent upon quiet behavior produced a marked decrease in inappropriate verbalizations. A return to contingent point loss was accompanied by an increasing rate of inappropriate verbalizations. Verbalizations decreased when quiet behavior was reinforced again. A noteworthy feature of the study was the utilization of students from within the class to act as data recorders. A reliability check indicated satisfactory agreement between the recorders.

Inflammation in subcutaneous adipose tissue: relationship to adipose cell size

AIMS/HYPOTHESIS

Inflammation is associated with increased body mass and purportedly with increased size of adipose cells. We sought to determine whether increased size of adipose cells is associated with localised inflammation in weight-stable, moderately obese humans.

METHODS

We recruited 49 healthy, moderately obese individuals for quantification of insulin resistance (modified insulin suppression test) and subcutaneous abdominal adipose tissue biopsy. Cell size distribution was analysed with a multisizer device and inflammatory gene expression with real-time PCR. Correlations between inflammatory gene expression and cell size variables, with adjustment for sex and insulin resistance, were calculated.

RESULTS

Adipose cells were bimodally distributed, with 47% in a 'large' cell population and the remainder in a 'small' cell population. The median diameter of the large adipose cells was not associated with expression of inflammatory genes. Rather, the fraction of small adipose cells was consistently associated with inflammatory gene expression, independently of sex, insulin resistance and BMI. This association was more pronounced in insulin-resistant than insulin-sensitive individuals. Insulin resistance also independently predicted expression of inflammatory genes.

CONCLUSIONS/INTERPRETATION

This study demonstrates that among moderately obese, weight-stable individuals an increased proportion of small adipose cells is associated with inflammation in subcutaneous adipose tissue, whereas size of mature adipose cells is not. The observed association between small adipose cells and inflammation may reflect impaired adipogenesis and/or terminal differentiation. However, it is unclear whether this is a cause or consequence of inflammation. This question and whether small vs large adipose cells contribute differently to inflammation in adipose tissue are topics for future research.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00285844.

Bridging from clinical endpoints to estimates of treatment value for external decision makers

AIM

While clinical endpoints provide important information on the efficacy of treatment in controlled conditions, they often are not relevant to decision makers trying to gauge the potential economic impact or value of new treatments. Therefore, it is often necessary to translate changes in cognition, function or behavior into changes in cost or other measures, which can be problematic if not conducted in a transparent manner. The Dependence Scale (DS), which measures the level of assistance a patient requires due to AD-related deficits, may provide a useful measure of the impact of AD progression in a way that is relevant to patients, providers and payers, by linking clinical endpoints to estimates of cost effectiveness or value. The aim of this analysis was to test the association of the DS to clinical endpoints and AD-related costs.

METHOD

The relationship between DS score and other endpoints was explored using the Predictors Study, a large, multi-center cohort of patients with probable AD followed annually for four years. Enrollment required a modified Mini-Mental State Examination (mMMS) score >or= 30, equivalent to a score of approximately >or= 16 on the MMSE. DS summated scores (range: 0- 15) were compared to measures of cognition (MMSE), function (Blessed Dementia Rating Scale, BDRS, 0-17), behavior, extrapyramidal symptoms (EPS), and psychotic symptoms (illusions, delusions or hallucinations). Also, estimates for total cost (sum of direct medical cost, direct non-medical cost, and cost of informal caregivers' time) were compared to DS scores.

RESULTS

For the 172 patients in the analysis, mean baseline scores were: DS: 5.2 (SD: 2.0), MMSE: 23.0 (SD: 3.5), BDRS: 2.9 (SD: 1.3), EPS: 10.8%, behavior: 28.9% psychotic symptoms: 21.1%. After 4 years, mean scores were: DS: 8.9 (SD: 2.9), MMSE: 17.2 (SD: 4.7), BDRS: 5.2 (SD: 1.4), EPS: 37.5%, behavior: 60.0%, psychotic symptoms: 46.7%. At baseline, DS scores were significantly correlated with MMSE (r=-0.299, p < 0.01), BDRS (r=0.610, p < 0.01), behavior (r=.2633, p=0.0005), EPS (r=0.1910, p=0.0137) and psychotic symptoms (r=0.253, p < 0.01); and at 4-year follow-up, DS scores were significantly correlated with MMSE (r=-0.3705, p=0.017), BDRS (r=0.6982, p < 0.001). Correlations between DS and behavior (-0.0085, p=0.96), EPS (r=0.3824, p=0.0794), psychotic symptoms (r=0.130, ns) were not statistically significant at follow-up. DS scores were also significantly correlated with total costs at baseline (r=0.2615, p=0.0003) and follow-up (r=0.3359, p=0.0318).

DISCUSSION

AD is associated with deficits in cognition, function and behavior, thus it is imperative that these constructs are assessed in trials of AD treatment. However, assessing multiple endpoints can lead to confusion for decision makers if treatments do not impact all endpoints similarly, especially if the measures are not used typically in practice. One potential method for translating these deficits into a more meaningful outcome would be to identify a separate construct, one that takes a broader view of the overall impact of the disease. Patient dependence, as measured by the DS, would appear to be a reasonable choice - it is associated with the three clinical endpoints, as well as measures of cost (medical and informal), thereby providing a bridge between measures of clinical efficacy and value in a single, transparent measure.

Azetidine-2-carboxylic acid in the food chain

Azetidine-2-carboxylic acid (Aze) 1 is a non-protein amino acid present in sugar beets and in table beets (Beta vulgaris). It is readily misincorporated into proteins in place of proline 2 in many species, including humans, and causes numerous toxic effects as well as congenital malformations. Its role in the pathogenesis of disease in humans has remained unexplored. Sugar beet agriculture, especially in the Northern Hemisphere, has become widespread during the past 150 years, and now accounts for nearly 30% of the world's supply of sucrose. Sugar beet byproducts are also used as a dietary supplement for livestock. Therefore, this study was undertaken as an initial survey to identify Aze-containing links in the food chain. Herein, we report the presence of Aze 1 in three sugar beet byproducts that are fed to farm animals: sugar beet molasses, shredded sugar beet pulp, and pelleted sugar beet pulp.

Persistence of improvement in insulin sensitivity following a dietary weight loss programme

AIM

Short-term dietary weight loss can improve insulin resistance but long-term studies are lacking. We sought to quantify the degree to which maintenance of weight loss after a short-term dietary intervention was associated with persistent metabolic benefits.

METHODS

Fifty-seven insulin-resistant obese subjects had insulin-mediated glucose disposal quantified through the steady-state plasma glucose (SSPG) test, and associated metabolic risk markers quantified at baseline, after a 16-week dietary weight loss intervention, and in 25 subjects, at follow-up of 28.8 +/- 13 months. Changes in metabolic variables over time were analysed and correlation with weight loss ascertained. Those with greatest vs. least long-term SSPG response (responders vs. non-responders) were compared. Multivariate analysis was performed for predictors of persistent SSPG response.

RESULTS

At follow-up, the 25 subjects who returned for metabolic testing had, on average, maintained their weight loss. Insulin-mediated glucose disposal remained significantly improved vs. baseline, as did plasma triglyceride and HDL cholesterol (HDL-C) concentrations, and improvement correlated with total amount of weight lost. Comparison of SSPG responders to non-responders showed no difference in amount of weight lost and SSPG change during the 16-week dietary intervention; however, SSPG non-responders regained 2.6% of weight lost, whereas responders lost an additional 1.5% at follow-up (p < 0.05 vs. non-responders). Non-responders had baseline characteristics consistent with more severe insulin resistance, including higher fasting plasma glucose (p = 0.03). Long-term SSPG change was independently predicted by both total weight loss (p = 0.005) and baseline fasting plasma glucose (p = 0.007).

CONCLUSIONS

Improvement in insulin sensitivity is maintained for 2-3 years following dietary weight loss if weight is not regained. Triglyceride and HDL-C concentrations also remain improved over time, consistent with improvement in insulin sensitivity. Fasting glucose and weight regain predict less long-term response in insulin sensitivity. These results highlight the potential long-term benefits of weight loss and importance of preventing weight regain among high-risk individuals.

Insulin resistance is associated with a modest increase in inflammation in subcutaneous adipose tissue of moderately obese women

AIMS/HYPOTHESIS

We have previously described differences in adipose cell size distribution and expression of genes related to adipocyte differentiation in subcutaneous abdominal fat obtained from insulin-sensitive (IS) and -resistant (IR) persons, matched for degree of moderate obesity. To determine whether other biological properties also differ between IR and IS obese individuals, we quantified markers of inflammatory activity in adipose tissue from overweight IR and IS individuals.

METHODS

Subcutaneous abdominal tissue was obtained from moderately obese women, divided into IR (n = 14) and IS (n = 19) subgroups by determining their steady-state plasma glucose (SSPG) concentrations during the insulin suppression test. Inflammatory activity was assessed by comparing expression of nine relevant genes and by immunohistochemical quantification of CD45- and CD68-containing cells.

RESULTS

SSPG concentrations were approximately threefold higher in IR than in IS individuals. Expression levels of CD68, EMR1, IL8, IL6 and MCP/CCL2 mRNAs were modestly but significantly increased (p < 0.05) in IR compared with IS participants. Results of immunohistochemical staining were consistent with gene expression data, demonstrating modest differences between IR and IS individuals. Crown-like structures, in which macrophages surround single adipocytes, were rarely seen in tissue from either subgroup.

CONCLUSIONS/INTERPRETATION

A modest increase in inflammatory activity was seen in subcutaneous adipose tissue from IR compared with equally obese IS individuals. Together with previous evidence of impaired adipose cell differentiation in IR vs equally obese individuals, it appears that at least two biological processes in subcutaneous adipose tissue characterize the insulin-resistant state independent of obesity per se.

Enhanced proportion of small adipose cells in insulin-resistant vs insulin-sensitive obese individuals implicates impaired adipogenesis

AIMS/HYPOTHESIS

The biological mechanism by which obesity predisposes to insulin resistance is unclear. One hypothesis is that larger adipose cells disturb metabolism via increased lipolysis. While studies have demonstrated that cell size increases in proportion to BMI, it has not been clearly shown that adipose cell size, independent of BMI, is associated with insulin resistance. The aim of this study was to test this widely held assumption by comparing adipose cell size distribution in 28 equally obese, otherwise healthy individuals who represented extreme ends of the spectrum of insulin sensitivity, as defined by the modified insulin suppression test.

SUBJECTS AND METHODS

Subcutaneous periumbilical adipose tissue biopsy samples were fixed in osmium tetroxide and passed through the Beckman Coulter Multisizer to obtain cell size distributions. Insulin sensitivity was quantified by the modified insulin suppression test. Quantitative real-time PCR for adipose cell differentiation genes was performed for 11 subjects.

RESULTS

All individuals exhibited a bimodal cell size distribution. Contrary to expectations, the mean diameter of the larger cells was not significantly different between the insulin-sensitive and insulin-resistant individuals. Moreover, insulin resistance was associated with a higher ratio of small to large cells (1.66 +/- 1.03 vs 0.94 +/- 0.50, p = 0.01). Similar cell size distributions were observed for isolated adipose cells. The real-time PCR results showed two- to threefold lower expression of genes encoding markers of adipose cell differentiation (peroxisome proliferator-activated receptor gamma1 [PPARgamma1], PPARgamma2, GLUT4, adiponectin, sterol receptor element binding protein 1c) in insulin-resistant compared with insulin-sensitive individuals.

CONCLUSIONS/INTERPRETATION

These results suggest that after controlling for obesity, insulin resistance is associated with an expanded population of small adipose cells and decreased expression of differentiation markers, suggesting that impairment in adipose cell differentiation may contribute to obesity-associated insulin resistance.

The relationship between insulin resistance and dyslipidaemia in cigarette smokers

AIM

Considerable evidence shows that cigarette smokers tend to have the dyslipidemic pattern of high plasma triglyceride (TG) and low high-density lipoprotein cholesterol (HDL-C) concentrations, a highly atherogenic lipoprotein profile also typical of the insulin-resistant state even in the absence of cigarette smoking. However, because cigarette smokers are frequently insulin resistant, it is unclear if this dyslipidaemia is secondary to smoking, per se, or simply to the fact that smokers tend to be insulin resistant. The present study was initiated to determine whether this dyslipidaemia prevalent in cigarette smokers and characteristic of insulin-resistant individuals is a function of cigarette smoking or of insulin resistance.

METHODS

As measured using vertical auto profile-II methodology, the lipid and lipoprotein concentrations were compared in 34 cigarette smokers divided into insulin-sensitive and insulin-resistant subgroups. The two groups were similar in age and body mass index, differing only in their insulin-mediated glucose uptake as quantified by the steady-state plasma glucose concentration determined during the insulin suppression test.

RESULTS

While levels of TG and very low-density lipoprotein cholesterol (VLDL-C) were significantly elevated in insulin-resistant cigarette smokers, total cholesterol (C), low-density lipoprotein cholesterol (LDL-C), narrow-density (ND) LDL-C, intermediate-density lipoprotein-C (IDL-C), HDL-C and non-HDL-C were not different in the two groups. The insulin-resistant smokers also had a preponderance of small, dense LDL particles, while the reverse was true of the insulin-sensitive cigarette smokers.

CONCLUSIONS

These data suggest that the dyslipidaemia previously attributed to smoking occurs primarily in those smokers who are also insulin resistant.

Metformin treatment lowers asymmetric dimethylarginine concentrations in patients with type 2 diabetes

This study was initiated to see if plasma asymmetric dimethylarginine (ADMA) concentrations decreased in hyperglycemic patients with type 2 diabetes following metformin treatment, either as monotherapy or following its addition to sulfonylurea-treated patients. Fasting plasma glucose, dimethylarginine, and L-arginine concentrations were measured before and 3 months after the administration of a maximally effective dose of metformin to 31 patients with type 2 diabetes in poor glycemic control (fasting plasma concentrations > 9.7 mmol/L), while being treated with either diet (n = 16) or a maximal amount of a sulfonylurea compound (n = 15). Fasting plasma glucose concentration (mean +/- SEM) decreased to a similar degree (P <.01) in patients treated with either metformin alone (12.4 +/- 0.5 to 9.5 +/- 0.5 mmol/L) or when it was added to a sulfonylurea compound (14.1 +/- 0.5 to 10.6 +/- 0.9 mmol/L). The improvement in glycemic control was associated with similar decreases (P <.01) in ADMA concentrations in metformin (1.65 +/- 0.21 to 1.18 +/- 0.13 micromol/L) and sulfonylurea + metformin-treated patients (1.75 +/- 0.13 to 1.19 +/- 0.08 micromol/L). Plasma L-arginine concentrations were similar in the 2 groups at baseline and did not change in response to metformin. Thus, metformin treatment was associated with a favorable increase in the plasma L-arginine/ADMA ratio. These results provide the first evidence that plasma ADMA concentrations decrease in association with improved glycemic control in patients with type 2 diabetes and demonstrate that the magnitude of the change in metformin-treated patients was similar, irrespective of whether it was used as monotherapy or in combination with sulfonylurea treatment.

Cost analysis of the use of inhaled corticosteroids in the treatment of asthma: a 1-year follow-up

A retrospective cohort using pharmacy and medical claims was analysed to determine whether the differences in efficacy of various inhaled corticosteroids demonstrated in clinical trials lead to differences in costs of care observed in clinical practice. Subjects that had an ICD-9 (493.XX) code for asthma and a new pharmacy claim for inhaled fluticasone propionate 44 mcg (FP), beclomethasone dipropionate (BDP), triamcinolone acetonide (TAA), budesonide (BUD) or flunisolide (FLU) were identified and followed for 12 months. Annual asthma care charges (pharmacy and medical) over the 12-month observation period were significantly (P < 0.03) higher in patients treated with BDPTAA, BUD and FLU compared to FP, 24%, 27%, 34% and 45% respectively In addition, patients treated with BDPTAA, and FLU were associated with significantly (P < 0.005) higher total healthcare (asthma + non-asthma) charges compared to patients on FP, 53%, 46% and 39% respectively Asthma care and total healthcare charges remained lower for FP after including FP110 mcg and excluding patients who were extreme cost outliers (+/- 2 SD from the mean) in a univariate sensitivity analysis. This analysis supports recent randomized control trials that FP offers a superior efficacy profile at lower asthma care as well as total healthcare charges compared to other inhaled corticosteroids.

Comorbid conditions in patients with erectile dysfunction in a community setting

The objective of this study was to assess the prevalence of chronic comorbidities and the use of concomitant medications in men diagnosed with erectile dysfunction (ED) in a community setting, using a large integrated database. All patients who experienced an episode of ED during a two-month period were identified from the database. Comorbid conditions were determined through outpatient management claims and prescription claims for concomitant conditions were also assessed during the study period.

Effect of insulin resistance on postprandial elevations of remnant lipoprotein concentrations in postmenopausal women

BACKGROUND

Questions remain as to why postmenopausal women are at a higher risk of coronary artery disease (CAD) than are premenopausal women. Studies have shown that plasma concentrations of remnant lipoproteins (RLPs) are elevated in patients with CAD and that increases in plasma RLP concentrations may be related to variations in insulin-mediated glucose disposal.

OBJECTIVE

We sought to evaluate the possibility that postprandial accumulation of plasma RLPs will be accentuated in insulin-resistant, postmenopausal women.

DESIGN

Postmenopausal women were divided into insulin-sensitive (n = 15) and insulin-resistant (n = 15) groups according to their steady state plasma glucose concentrations in response to a 180-min infusion of octreotide, insulin, and glucose. Plasma insulin, triacylglycerol, and RLP-cholesterol concentrations were measured either hourly (insulin) or every 2 h (triacylglycerol and RLP cholesterol) for 8 h, before and after breakfast (0800) and lunch (1200).

RESULTS

By selection, insulin-resistant women had higher steady state plasma glucose concentrations than did insulin-sensitive women (10.8 +/- 0.5 compared with 4.1 +/- 5 mmol/L, respectively; P < 0.001), associated with higher fasting triacylglycerol (1.58 +/- 0.04 compared with 1.00 +/- 0.03 mmol/L; P = 0.01) and lower HDL-cholesterol (1.06 +/- 0.08 compared with 1.34 +/- 0.05; P = 0.01) concentrations. In addition, measurements of daylong concentrations of insulin, triacylglycerol, and RLP cholesterol were also significantly greater in insulin-resistant than in insulin-sensitive women (P < 0.001).

CONCLUSIONS

Postprandial accumulation of RLPs is accentuated in insulin-resistant, postmenopausal women. This may contribute to the increased risk of CAD in these individuals.

Topographic-specific axon branching controlled by ephrin-As is the critical event in retinotectal map development

The retinotectal projection is the predominant model for studying molecular mechanisms controlling development of topographic axonal connections. Our analyses of topographic mapping of retinal ganglion cell (RGC) axons in chick optic tectum indicate that a primary role for guidance molecules is to regulate topographic branching along RGC axons, a process that imposes unique requirements on the molecular control of map development. We show that topographically appropriate connections are established exclusively by branches that form along the axon shaft. Initially, RGC axons overshoot their appropriate termination zone (TZ) along the anterior-posterior (A-P) tectal axis; temporal axons overshoot the greatest distance and nasal axons the least, which correlates with the nonlinear increasing A-P gradient of ephrin-A repellents. In contrast, branches form along the shaft of RGC axons with substantial A-P topographic specificity. Topography is enhanced through the preferential arborization of appropriately positioned branches and elimination of ectopic branches. Using a membrane stripe assay and time-lapse microscopy, we show that branches form de novo along retinal axons. Temporal axons preferentially branch on their topographically appropriate anterior tectal membranes. After the addition of soluble EphA3-Fc, which blocks ephrin-A function, temporal axons branch equally on anterior and posterior tectal membranes, indicating that the level of ephrin-As in posterior tectum is sufficient to inhibit temporal axon branching and generate branching specificity in vitro. Our findings indicate that topographic branch formation and arborization along RGC axons are critical events in retinotectal mapping. Ephrin-As inhibit branching along RGC axons posterior to their correct TZ, but alone cannot account for topographic branching and must cooperate with other molecular activities to generate appropriate mapping along the A-P tectal axis.

Prevalence of treated dry eye disease in a managed care population

BACKGROUND

Survey studies are of limited utility in estimating the prevalence of treated dry eye. The use of claims data, which include only individuals who have a diagnosis of the disorder, provides a better estimation of the clinical significance of dry eye symptoms and appraisal of community needs.

OBJECTIVE

The purpose of this paper is to estimate the prevalence of treated dry eye disease using a nonsurvey methodology.

METHODS

Patients with dry eye diagnoses or who underwent punctal occlusion procedures were identified from PharMetrics' Integrated Outcomes database of medical claims for approximately 10 million patients enrolled in managed care plans. Prevalence estimates were calculated for 1997 and 1998.

RESULTS

The prevalence of dry eye was 0.48% in 1997 and 0.39% in 1998, representing 25,180 and 27,289 cases, respectively. Patients aged > or = 65 years were approximately 4 times as likely as those aged < 65 years to be diagnosed with keratoconjunctivitis sicca or tear film insufficiency. In 1997, dry eye was diagnosed or treated in 0.65% of women compared with 0.26% of men (P < 0.001). Rates of dry eye disease in 1998 were highest among women aged 75 to 79 years (2.02%) and men aged 80 to 84 years (1.30%). Women tended to receive a diagnosis at a younger age than did men. The most common diagnosis was tear film insufficiency (73.96% and 73.41% of dry eye patients in 1997 and 1998, respectively). The most common procedure was lacrimal punctal occlusion by plug (7.78% and 8.74% of dry eye patients in 1997 and 1998, respectively).

CONCLUSION

The prevalence of treated dry eye disease is 0.4% to 0.5% and is highest among women and the elderly.

Comparison of rheumatoid arthritis care costs in patients starting therapy with leflunomide versus etanercept

OBJECTIVE

To identify differences in rheumatoid arthritis (RA) care costs and utilization among patients receiving therapy with leflunomide (LEF) or etanercept (ETA).

STUDY DESIGN

A retrospective cohort analysis of patients diagnosed with RA and starting treatment with LEF or ETA.

METHODS

Patients diagnosed with RA and receiving newly prescribed LEF or ETA in 1998 were identified from a database containing patient-level medical and pharmaceutical claims. Patients were subsequently observed for 6 months. RA-related treatment charges during the observation period were compared between cohorts.

RESULTS

A total of 527 LEF- and 281 ETA-treated patients were identified. The 2 cohorts were comparable with respect to demographics, comorbid conditions, and concomitant medication use, although LEF recipients were, on average, older than ETA recipients (mean age 52.97 versus 48.43 years; P < .0001). ETA recipients had higher mean 6-month postdiagnosis charges than LEF recipients ($7722.01 +/- $5285.20 versus $3301.84 +/- $4054.75; P < .0001). This difference was primarily related to differences in RA-related pharmacy charges ($5877.78 +/- $2237.68 versus $1877.23 +/- $1258.05; P < .0001).

CONCLUSIONS

Compared with charges in the ETA group, RA care costs in the LEF group were significantly lower during the 6 months after the initiation of therapy. The difference in mean total RA-related charges was attributable mainly to the difference in RA-related pharmacy charges.

Relationship between insulin resistance, weight loss, and coronary heart disease risk in healthy, obese women

Several popular books have recently been published stating that being insulin-resistant favors weight gain and/or prevents weight loss. Because this view seems to have gained widespread support in the general population, we thought it important to perform the current study testing the hypothesis that differences in insulin-mediated glucose disposal do not affect weight loss in response to calorie-restricted diets. For this purpose, we studied the change in weight and risk factors for coronary heart disease (CHD) in healthy women volunteers, defined as being obese on the basis of a body mass index (BMI) greater than 30.0 kg/m(2). The insulin suppression test was used to stratify obese women at baseline into insulin-resistant and insulin-sensitive subgroups on the basis of their steady-state plasma glucose (SSPG) concentration at the end of a 180-minute infusion of octreotide, exogenous insulin, and glucose. They were then instructed on a calorie-restricted diet plus sibutraminine (15 mg/day) for a total period of 4 months. Baseline measurements also included determination of fasting lipid and lipoprotein concentrations, and hourly (8 AM to 4 PM) determinations of plasma glucose and insulin concentrations before and after breakfast and lunch. Twenty-four women completed the 4-month period of calorie restriction: 13 classified as insulin-resistant (SSPG = 219 +/- 7 mg/dL) and 11 as insulin-sensitive (SSPG = 69 +/- 6 mg/dL). The insulin-resistant group also had higher (P =.03) plasma triglyceride (TG) concentrations and a higher ratio of total to high-density lipoprotein (HDL) cholesterol concentration (P =.02) at baseline. Both groups lost a significant amount of weight during the study, and there was no difference between the weight loss in the insulin-resistant (8.6 +/- 1.3 kg) and insulin-sensitive (7.9 +/- 1.4 kg) groups. Weight loss in the insulin-resistant group was also associated with a significant decrease in SSPG concentration (219 +/- 7 to 144 +/- 14 mg/dL), associated with significantly lower fasting TG concentrations (P <.001) and day-long concentrations of plasma glucose and insulin (P <.005). None of these variables changed in the insulin-sensitive group. These results indicate that: (1) CHD risk factors in obese women vary as a function of being insulin-resistant or insulin-sensitive; (2) dramatic variations in insulin-mediated glucose disposal do not modulate weight loss in response to calorie-restricted diets, and (3) weight loss is effective in reducing CHD risk in insulin-resistant, obese women. Given these data, it seems obvious that attempts to reduce CHD risk factors by weight loss should focus on obese individuals who are also insulin-resistant.

Metabolic changes following sibutramine-assisted weight loss in obese individuals: role of plasma free fatty acids in the insulin resistance of obesity

The relationship between insulin-mediated glucose disposal and daylong free fatty acid (FFA) concentrations before and after sibutramine-assisted weight loss was investigated in 24 healthy, normotensive, nondiabetic, obese women (body mass index [BMI] >30.0 kg/m(2)). The 24 volunteers were defined as being insulin-resistant (IR) or insulin-sensitive (IS) on the basis of their steady-state plasma glucose (SSPG) concentration in response to a 180-minute continuous intravenous infusion of octreotide, insulin, and glucose. The mean (+/- SEM) SSPG concentrations were significantly higher (P <.001) in the IR group (219 +/- 7 v 69 +/- 6 mg/dL) at baseline. The IR group also had significantly higher plasma glucose (P =.002), insulin (P <.001), and FFA (P =.02) concentrations measured at hourly intervals from 8 AM to 4 PM, before and after breakfast (8 AM) and lunch (noon). Weight loss in response to an energy-restricted diet for 4 months and sibutramine (15 mg/d) was comparable in the 2 experimental groups (8.6 +/- 1.3 v 7.9 +/- 1.4 kg). SSPG concentrations decreased significantly (P <.001) following weight loss (219 +/- 7 to 144 +/- mg/dL) in the IR group, but there was no change in the SSPG of the IS group (69 +/- 6 to 73 +/- 7 mg/dL. The improvement in insulin sensitivity in the IR group after weight loss was associated with a significant decline in daylong plasma glucose (P >.001) and insulin (P =.02) concentrations, without a weight-loss-associated decrease in daylong plasma FFA responses. In contrast, there was no significant change in plasma glucose, insulin, and FFA concentrations following weight loss in the IS group. These results indicate that daylong FFA concentrations vary substantially in obese individuals as a function of whether they are IR or IS. Furthermore the observation that the IR group was more insulin-sensitive after weight loss, associated with lower daylong insulin concentrations in the absence of a significant decrease in circulating FFA concentrations, suggests that resistance to insulin-mediated glucose disposal in obese individuals cannot be entirely due to high FFA levels.

Medical secretaries. Making the grade

A review of the role of medical secretaries in a surgical directorate has reduced turnover among this group to zero. Previously the directorate had difficulty with recruitment and often had to rely on agency staff. The review led to the introduction of the new post of business coordinator, and all medical secretaries in the directorate have now achieved this level. The review led to an expanded role for medical secretaries which has increased their job satisfaction.

Insulin resistance, dietary cholesterol, and cholesterol concentration in postmenopausal women

Questions remain concerning the effect of variations in cholesterol intake on plasma cholesterol concentration, as well as on the role of factors modulating the metabolic impact of this dietary intervention. To define the impact of wide variations in dietary cholesterol intake on plasma total and low-density lipoprotein (LDL) cholesterol concentrations, as well as testing the hypothesis that resistance to insulin-mediated glucose disposal would accentuate the increase in plasma total and LDL cholesterol concentrations in response to a given increment in dietary cholesterol intake, we performed a prospective, randomized study comparing diets varying in cholesterol content in 65 healthy, postmenopausal women, 31 defined as insulin-resistant and 34 as insulin-sensitive. The changes in total and LDL cholesterol in response to increments in dietary cholesterol of up to approximately 800 mg/day were modest in magnitude, without evidence of a statistically significant diet-induced increase in cholesterol concentration, or of any difference in the responses of insulin-resistant as compared with insulin-sensitive women. These results indicate that relatively large increments in dietary cholesterol intake had little effect on total or LDL cholesterol concentrations in healthy, postmenopausal women, irrespective of whether they were insulin-resistant or insulin-sensitive.