Differential Viral Dynamics by Sex and Body Mass Index During Acute SARS-CoV-2 Infection: Results from a Longitudinal Cohort Study

BACKGROUND

There is evidence of an association of severe COVID-19 outcomes with increased body mass index (BMI) and male sex. However, few studies have examined the interaction between sex and BMI on SARS-CoV-2 viral dynamics.

METHODS

Participants conducted RT-PCR testing every 24-48 hours over a 15-day period. Sex and BMI were self-reported, and Ct values from E-gene were used to quantify viral load. Three distinct outcomes were examined using mixed effects generalized linear models, linear models, and logistic models, respectively: all Ct values (Model 1); nadir Ct value (model 2); and strongly detectable infection (at least one Ct value ≤28 during their infection) (Model 3). An interaction term between BMI and sex was included, and inverse logit transformations were applied to quantify the differences by BMI and sex using marginal predictions.

RESULTS

In total, 7,988 participants enrolled in this study, and 439 participants (Model 1) and 309 (Model 2 and 3) were eligible for these analyses. Among males, increasing BMI was associated with lower Ct values in a dose-response fashion. For participants with BMIs greater than 29, males had significantly lower Ct values and nadir Ct values than females. In total, 67.8% of males and 55.3% of females recorded a strongly detectable infection; increasing proportions of men had Ct values <28 with BMIs of 35 and 40.

CONCLUSIONS

We observed sex-based dimorphism in relation to BMI and COVID-19 viral load. Further investigation is needed to determine the cause, clinical impact, and transmission implications of this sex-differential effect of BMI on viral load.

Association of neighborhood-level sociodemographic factors with Direct-to-Consumer (DTC) distribution of COVID-19 rapid antigen tests in 5 US communities

BACKGROUND

Many interventions for widescale distribution of rapid antigen tests for COVID-19 have utilized online, direct-to-consumer (DTC) ordering systems; however, little is known about the sociodemographic characteristics of home-test users. We aimed to characterize the patterns of online orders for rapid antigen tests and determine geospatial and temporal associations with neighborhood characteristics and community incidence of COVID-19, respectively.

METHODS

This observational study analyzed online, DTC orders for rapid antigen test kits from beneficiaries of the Say Yes! Covid Test program from March to November 2021 in five communities: Louisville, Kentucky; Indianapolis, Indiana; Fulton County, Georgia; O'ahu, Hawaii; and Ann Arbor/Ypsilanti, Michigan. Using spatial autoregressive models, we assessed the geospatial associations of test kit distribution with Census block-level education, income, age, population density, and racial distribution and Census tract-level Social Vulnerability Index. Lag association analyses were used to measure the association between online rapid antigen kit orders and community-level COVID-19 incidence.

RESULTS

In total, 164,402 DTC test kits were ordered during the intervention. Distribution of tests at all sites were significantly geospatially clustered at the block-group level (Moran's I: p < 0.001); however, education, income, age, population density, race, and social vulnerability index were inconsistently associated with test orders across sites. In Michigan, Georgia, and Kentucky, there were strong associations between same-day COVID-19 incidence and test kit orders (Michigan: r = 0.89, Georgia: r = 0.85, Kentucky: r = 0.75). The incidence of COVID-19 during the current day and the previous 6-days increased current DTC orders by 9.0 (95% CI = 1.7, 16.3), 3.0 (95% CI = 1.3, 4.6), and 6.8 (95% CI = 3.4, 10.2) in Michigan, Georgia, and Kentucky, respectively. There was no same-day or 6-day lagged correlation between test kit orders and COVID-19 incidence in Indiana.

CONCLUSIONS

Our findings suggest that online ordering is not associated with geospatial clustering based on sociodemographic characteristics. Observed temporal preferences for DTC ordering can guide public health messaging around DTC testing programs.

Performance of Rapid Antigen Tests to Detect Symptomatic and Asymptomatic SARS-CoV-2 Infection : A Prospective Cohort Study

BACKGROUND

The performance of rapid antigen tests (Ag-RDTs) for screening asymptomatic and symptomatic persons for SARS-CoV-2 is not well established.

OBJECTIVE

To evaluate the performance of Ag-RDTs for detection of SARS-CoV-2 among symptomatic and asymptomatic participants.

DESIGN

This prospective cohort study enrolled participants between October 2021 and January 2022. Participants completed Ag-RDTs and reverse transcriptase polymerase chain reaction (RT-PCR) testing for SARS-CoV-2 every 48 hours for 15 days.

SETTING

Participants were enrolled digitally throughout the mainland United States. They self-collected anterior nasal swabs for Ag-RDTs and RT-PCR testing. Nasal swabs for RT-PCR were shipped to a central laboratory, whereas Ag-RDTs were done at home.

PARTICIPANTS

Of 7361 participants in the study, 5353 who were asymptomatic and negative for SARS-CoV-2 on study day 1 were eligible. In total, 154 participants had at least 1 positive RT-PCR result.

MEASUREMENTS

The sensitivity of Ag-RDTs was measured on the basis of testing once (same-day), twice (after 48 hours), and thrice (after a total of 96 hours). The analysis was repeated for different days past index PCR positivity (DPIPPs) to approximate real-world scenarios where testing initiation may not always coincide with DPIPP 0. Results were stratified by symptom status.

RESULTS

Among 154 participants who tested positive for SARS-CoV-2, 97 were asymptomatic and 57 had symptoms at infection onset. Serial testing with Ag-RDTs twice 48 hours apart resulted in an aggregated sensitivity of 93.4% (95% CI, 90.4% to 95.9%) among symptomatic participants on DPIPPs 0 to 6. When singleton positive results were excluded, the aggregated sensitivity on DPIPPs 0 to 6 for 2-time serial testing among asymptomatic participants was lower at 62.7% (CI, 57.0% to 70.5%), but it improved to 79.0% (CI, 70.1% to 87.4%) with testing 3 times at 48-hour intervals.

LIMITATION

Participants tested every 48 hours; therefore, these data cannot support conclusions about serial testing intervals shorter than 48 hours.

CONCLUSION

The performance of Ag-RDTs was optimized when asymptomatic participants tested 3 times at 48-hour intervals and when symptomatic participants tested 2 times separated by 48 hours.

PRIMARY FUNDING SOURCE

National Institutes of Health RADx Tech program.

Design and implementation of a digital site-less clinical study of serial rapid antigen testing to identify asymptomatic SARS-CoV-2 infection

Background

Rapid antigen detection tests (Ag-RDT) for SARS-CoV-2 with emergency use authorization generally include a condition of authorization to evaluate the test's performance in asymptomatic individuals when used serially. We aim to describe a novel study design that was used to generate regulatory-quality data to evaluate the serial use of Ag-RDT in detecting SARS-CoV-2 virus among asymptomatic individuals.

Methods

This prospective cohort study used a siteless, digital approach to assess longitudinal performance of Ag-RDT. Individuals over 2 years old from across the USA with no reported COVID-19 symptoms in the 14 days prior to study enrollment were eligible to enroll in this study. Participants throughout the mainland USA were enrolled through a digital platform between October 18, 2021 and February 15, 2022. Participants were asked to test using Ag-RDT and molecular comparators every 48 hours for 15 days. Enrollment demographics, geographic distribution, and SARS-CoV-2 infection rates are reported.

Key Results

A total of 7361 participants enrolled in the study, and 492 participants tested positive for SARS-CoV-2, including 154 who were asymptomatic and tested negative to start the study. This exceeded the initial enrollment goals of 60 positive participants. We enrolled participants from 44 US states, and geographic distribution of participants shifted in accordance with the changing COVID-19 prevalence nationwide.

Conclusions

The digital site-less approach employed in the "Test Us At Home" study enabled rapid, efficient, and rigorous evaluation of rapid diagnostics for COVID-19 and can be adapted across research disciplines to optimize study enrollment and accessibility.

Performance of Rapid Antigen Tests Based on Symptom Onset and Close Contact Exposure: A secondary analysis from the Test Us At Home prospective cohort study

Background

The performance of rapid antigen tests for SARS-CoV-2 (Ag-RDT) in temporal relation to symptom onset or exposure is unknown, as is the impact of vaccination on this relationship.

Objective

To evaluate the performance of Ag-RDT compared with RT-PCR based on day after symptom onset or exposure in order to decide on 'when to test'.

Design Setting and Participants

The Test Us at Home study was a longitudinal cohort study that enrolled participants over 2 years old across the United States between October 18, 2021 and February 4, 2022. All participants were asked to conduct Ag-RDT and RT-PCR testing every 48 hours over a 15-day period. Participants with one or more symptoms during the study period were included in the Day Post Symptom Onset (DPSO) analyses, while those who reported a COVID-19 exposure were included in the Day Post Exposure (DPE) analysis.

Exposure

Participants were asked to self-report any symptoms or known exposures to SARS-CoV-2 every 48-hours, immediately prior to conducting Ag-RDT and RT-PCR testing. The first day a participant reported one or more symptoms was termed DPSO 0, and the day of exposure was DPE 0. Vaccination status was self-reported.

Main Outcome and Measures

Results of Ag-RDT were self-reported (positive, negative, or invalid) and RT-PCR results were analyzed by a central laboratory. Percent positivity of SARS-CoV-2 and sensitivity of Ag-RDT and RT-PCR by DPSO and DPE were stratified by vaccination status and calculated with 95% confidence intervals.

Results

A total of 7,361 participants enrolled in the study. Among them, 2,086 (28.3%) and 546 (7.4%) participants were eligible for the DPSO and DPE analyses, respectively. Unvaccinated participants were nearly twice as likely to test positive for SARS-CoV-2 than vaccinated participants in event of symptoms (PCR+: 27.6% vs 10.1%) or exposure (PCR+: 43.8% vs. 22.2%). The highest proportion of vaccinated and unvaccinated individuals tested positive on DPSO 2 and DPE 5-8. Performance of RT-PCR and Ag-RDT did not differ by vaccination status. Ag-RDT detected 78.0% (95% Confidence Interval: 72.56-82.61) of PCR-confirmed infections by DPSO 4. For exposed participants, Ag-RDT detected 84.9% (95% CI: 75.0-91.4) of PCR-confirmed infections by day five post-exposure (DPE 5).

Conclusions and Relevance

Performance of Ag-RDT and RT-PCR was highest on DPSO 0-2 and DPE 5 and did not differ by vaccination status. These data suggests that serial testing remains integral to enhancing the performance of Ag-RDT.

Performance of Rapid Antigen Tests to Detect Symptomatic and Asymptomatic SARS-CoV-2 Infection

Background

Performance of rapid antigen tests for SARS-CoV-2 (Ag-RDT) varies over the course of an infection, and their performance in screening for SARS-CoV-2 is not well established. We aimed to evaluate performance of Ag-RDT for detection of SARS-CoV-2 for symptomatic and asymptomatic participants.

Methods

Participants >2 years old across the United States enrolled in the study between October 2021 and February 2022. Participants completed Ag-RDT and molecular testing (RT-PCR) for SARS-CoV-2 every 48 hours for 15 days. This analysis was limited to participants who were asymptomatic and tested negative on their first day of study participation. Onset of infection was defined as the day of first positive RT-PCR result. Sensitivity of Ag-RDT was measured based on testing once, twice (after 48-hours), and thrice (after 96 hours). Analysis was repeated for different Days Post Index PCR Positivity (DPIPP) and stratified based on symptom-status.

Results

In total, 5,609 of 7,361 participants were eligible for this analysis. Among 154 participants who tested positive for SARS-CoV-2, 97 were asymptomatic and 57 had symptoms at infection onset. Serial testing with Ag-RDT twice 48-hours apart resulted in an aggregated sensitivity of 93.4% (95% CI: 89.1-96.1%) among symptomatic participants on DPIPP 0-6. Excluding singleton positives, aggregated sensitivity on DPIPP 0-6 for two-time serial-testing among asymptomatic participants was lower at 62.7% (54.7-70.0%) but improved to 79.0% (71.0-85.3%) with testing three times at 48-hour intervals.

Discussion

Performance of Ag-RDT was optimized when asymptomatic participants tested three-times at 48-hour intervals and when symptomatic participants tested two-times separated by 48-hours.

Finding a Needle in a Haystack: Design and Implementation of a Digital Site-less Clinical Study of Serial Rapid Antigen Testing to Identify Asymptomatic SARS-CoV-2 Infection

Background

Rapid antigen tests (Ag-RDT) for SARS-CoV-2 with Emergency Use Authorization generally include a condition of authorization to evaluate the test's performance in asymptomatic individuals when used serially.

Objective

To describe a novel study design to generate regulatory-quality data to evaluate serial use of Ag-RDT in detecting SARS-CoV-2 virus among asymptomatic individuals.

Design

Prospective cohort study using a decentralized approach. Participants were asked to test using Ag-RDT and molecular comparators every 48 hours for 15 days.

Setting

Participants throughout the mainland United States were enrolled through a digital platform between October 18, 2021 and February 15, 2022. Ag-RDTs were completed at home, and molecular comparators were shipped to a central laboratory.

Participants

Individuals over 2 years old from across the U.S. with no reported COVID-19 symptoms in the 14 days prior to study enrollment were eligible to enroll in this study.

Measurements

Enrollment demographics, geographic distribution, and SARS-CoV-2 infection rates are reported.

Key Results

A total of 7,361 participants enrolled in the study, and 492 participants tested positive for SARS-CoV-2, including 154 who were asymptomatic and tested negative to start the study. This exceeded the initial enrollment goals of 60 positive participants. We enrolled participants from 44 U.S. states, and geographic distribution of participants shifted in accordance with the changing COVID-19 prevalence nationwide.

Limitations

New, complex workflows required significant operational and data team support. Conclusions: The digital site-less approach employed in the 'Test Us At Home' study enabled rapid, efficient, and rigorous evaluation of rapid diagnostics for COVID-19, and can be adapted across research disciplines to optimize study enrollment and accessibility.

Epidemiology and impact of frailty in patients with atrial fibrillation in Europe

BACKGROUND

Frailty is a medical syndrome characterised by reduced physiological reserve and increased vulnerability to stressors. Data regarding the relationship between frailty and atrial fibrillation (AF) are still inconsistent.

OBJECTIVES

We aim to perform a comprehensive evaluation of frailty in a large European cohort of AF patients.

METHODS

A 40-item frailty index (FI) was built according to the accumulation of deficits model in the AF patients enrolled in the ESC-EHRA EORP-AF General Long-Term Registry. Association of baseline characteristics, clinical management, quality of life, healthcare resources use and risk of outcomes with frailty was examined.

RESULTS

Among 10,177 patients [mean age (standard deviation) 69.0 (11.4) years, 4,103 (40.3%) females], 6,066 (59.6%) were pre-frail and 2,172 (21.3%) were frail, whereas only 1,939 (19.1%) were considered robust. Baseline thromboembolic and bleeding risks were independently associated with increasing FI. Frail patients with AF were less likely to be treated with oral anticoagulants (OACs) (odds ratio 0.70, 95% confidence interval 0.55-0.89), especially with non-vitamin K antagonist OACs and managed with a rhythm control strategy, compared with robust patients. Increasing frailty was associated with a higher risk for all outcomes examined, with a non-linear exponential relationship. The use of OAC was associated with a lower risk of outcomes, except in patients with very/extremely high frailty.

CONCLUSIONS

In this large cohort of AF patients, there was a high burden of frailty, influencing clinical management and risk of adverse outcomes. The clinical benefit of OAC is maintained in patients with high frailty, but not in very high/extremely frail ones.

Association of Mass Distribution of Rapid Antigen Tests and SARS-CoV-2 Prevalence: Results from NIH-CDC funded Say Yes! Covid Test program in Michigan

Importance

Wide-spread distribution of diagnostics is an integral part of the United States’ COVID-19 strategy; however, few studies have assessed the effectiveness of this intervention at reducing transmission of community COVID-19.

Objective

To assess the impact of the Say Yes! Covid Test (SYCT!) Michigan program, a population-based program that distributed 20,000 free rapid antigen tests within Ann Arbor and Ypsilanti, Michigan in June-August 2021, on community prevalence of SARS-CoV-2.

Design

This ecological study analyzed cases of SARS-CoV-2 from March to October 2021 reported to the Washtenaw County Health Department.

Setting

Washtenaw County, Michigan.

Participants

All residents of Washtenaw County.

Interventions

Community-wide distribution of 500,000 rapid antigen tests for SARS-CoV-2 to residents of Ann Arbor and Ypsilanti, Michigan. Each household was limited to one test kit containing 25 rapid antigen tests.

Main Outcome and Measures

Community prevalence of SARS-CoV-2, as measured through 7-day average cases, in Ann Arbor and Ypsilanti was compared to the rest of Washtenaw County. A generalized additive model was fitted with non-parametric trends for control and relative differences of trends in the pre-intervention, intervention, and post-intervention periods to compare intervention municipalities of Ann Arbor and Ypsilanti to the rest of Washtenaw County. Model results were used to calculate average cases prevented in the post-intervention period.

Results

In the post-intervention period, there were significantly lower standardized average cases in the intervention communities of Ann Arbor/Ypsilanti compared to the rest of Washtenaw County (p<0.001). The estimated standardized relative difference between Ann Arbor/Ypsilanti and the rest of Washtenaw County was -0.016 cases per day (95% CI: -0.020 to -0.013), implying that the intervention prevented 40 average cases per day two months into the post-intervention period if trends were consistent.

Conclusions and Relevance

Mass distribution of rapid antigen tests may be a useful mitigation strategy to combat community transmission of SARS-CoV-2, especially given the recent relaxation of social distancing and masking requirements.

Short Term Changes in Dietary Fat Content and Metformin Treatment During Lactation Impact Milk Composition and Mammary Gland Morphology

Maternal health and diet can have important consequences for offspring nutrition and metabolic health. During lactation, signals are communicated from the mother to the infant through milk via macronutrients, hormones, and bioactive molecules. In this study we designed experiments to probe the mother-milk-infant triad in the condition of normal maternal health and upon exposure to high fat diet (HFD) with or without concurrent metformin exposure. We examined maternal characteristics, milk composition and offspring metabolic parameters on postnatal day 16, prior to offspring weaning. We found that lactational HFD increased maternal adipose tissue weight, mammary gland adipocyte size, and altered milk lipid composition causing a higher amount of omega-6 (n6) long chain fatty acids and lower omega-3 (n3). Offspring of HFD dams were heavier with more body fat during suckling. Metformin (Met) exposure decreased maternal blood glucose and several milk amino acids. Offspring of met dams were smaller during suckling. Gene expression in the lactating mammary glands was impacted to a greater extent by metformin than HFD, but both metformin and HFD altered genes related to muscle contraction, indicating that these genes may be more susceptible to lactational stressors. Our study demonstrates the impact of common maternal exposures during lactation on milk composition, mammary gland function and offspring growth with metformin having little capacity to rescue the offspring from the effects of a maternal HFD during lactation.

Impact of maternal overweight and obesity on milk composition and infant growth

Overweight and obesity (OW/OB) impact half of the pregnancies in the United States and can have negative consequences for offspring health. Studies are limited on human milk alterations in the context of maternal obesity. Alterations in milk are hypothesized to impact offspring development during the critical period of lactation. We aimed to evaluate the relationships between mothers with OW/OB (body mass index [BMI] ≥25 kg/m2 ), infant growth, and selected milk nutrients. We recruited mother-infant dyads with pre-pregnancy OW/OB and normal weight status. The primary study included 52 dyads with infant growth measures through 6 months. Thirty-two dyads provided milk at 2 weeks, which was analysed for macronutrients, long-chain fatty acids, and insulin. We used multivariable linear regression to examine the association of maternal weight status with infant growth, maternal weight status with milk components, and milk components with infant growth. Mothers with OW/OB had infants with higher weight-for-length (WFL) and BMI Z-scores at birth. Mothers with OW/OB had higher milk insulin and dihomo-gamma-linolenic, adrenic, and palmitic acids and reduced conjugated linoleic and oleic acids. N6 long-chain polyunsaturated fatty acid (LC-PUFA)-driven factor 1 was associated with higher WFL, lower length-for-age (LFA), and lower head circumference-for-age Z-scores change from 2 weeks to 2 months in human milk-fed infants, whereas N6 LC-PUFA-driven factor 5 was associated with lower LFA Z-score change. Human milk composition is associated with maternal pre-pregnancy weight status and composition may be a contributing factor to early infant growth trajectory.

Breast Milk Iodine Concentration Is Associated with Infant Growth, Independent of Maternal Weight

In breastfed infants, human milk provides the primary source of iodine to meet demands during this vulnerable period of growth and development. Iodine is a key micronutrient that plays an essential role in hormone synthesis. Despite the importance of iodine, there is limited understanding of the maternal factors that influence milk iodine content and how milk iodine intake during infancy is related to postnatal growth. We examined breast milk samples from near 2 weeks and 2 months post-partum in a mother-infant dyad cohort of mothers with pre-pregnancy weight status defined by body mass index (BMI). Normal (NW, BMI < 25.0 kg/m2) is compared to overweight/obesity (OW/OB, BMI ≥ 25.0 kg/m2). The milk iodine concentration was determined by inductively coupled plasma mass spectrometry. We evaluated the associations between iodine content at 2 weeks and infant anthropometrics over the first year of life using multivariable linear mixed modeling. Iodine concentrations generally decreased from 2 weeks to 2 months. We observed no significant difference in iodine based on maternal weight. A higher iodine concentration at 2 weeks was associated with a larger increase in infant weight-for-age and weight-for-length Z-score change per month from 2 weeks to 1 year. This pilot study shows that early iodine intake may influence infant growth trajectory independent of maternal pre-pregnancy weight status.

Lactational programming of glucose homeostasis: a window of opportunity

The window of lactation is a critical period during which nutritional and environmental exposures impact lifelong metabolic disease risk. Significant organ and tissue development, organ expansion and maturation of cellular functions occur during the lactation period, making this a vulnerable time during which transient insults can have lasting effects. This review will cover current literature on factors influencing lactational programming such as milk composition, maternal health status and environmental endocrine disruptors. The underlying mechanisms that have the potential to contribute to lactational programming of glucose homeostasis will also be addressed, as well as potential interventions to reduce offspring metabolic disease risk.

The gap between the current dyslipidemia guidelines and the physicians' treatment targets in patients with type 2 diabetes in Turkey

AIM

Lipid-lowering therapy (LLT) is a key factor in the prevention of cardiovascular mortality and morbidity in diabetic patients. Current guidelines have expanded the population of patients with diabetes for whom aggressive low-density lipoprotein cholesterol (LDL-C) lowering therapy should be considered. This study evaluated the management of dyslipidemia in patients with type 2 diabetes in real life.

METHODS

Secondary care physicians in a tertiary center recruited 707 patients. The prevalence of statin use along with the achievement of cholesterol targets, predictors for receiving statin, and possible reasons for lack of therapy were investigated.

RESULTS

Only 33% of the patients had received statin therapy, and this was significantly higher in those with cardiovascular disease (47% versus 27%; P<0.001). Most of the patients had LDL-C levels of >100 mg/dL (77%), with only 5% having LDL-C levels of <70 mg/dL. Forty-one percent of the patients had never been prescribed LLT previously while 26% had been prescribed this type of therapy in the past but had stopped using it. The most frequent reason for discontinuation of the statin therapy was a physician's advice to stop the medication. The patients taking statins had similar LDL-C levels as those who had never been prescribed statins and those who had discontinued their use of statins on the advice of a physician.

CONCLUSION

The majority of diabetic patients are undertreated with statins and minority of them achieve LDL-C target levels. Our findings suggest that there is a large discrepency between evidence-based recommendations and physicians' treatment attitudes.

Increased oxidative DNA damage in lean normoglycemic offspring of type 2 diabetic patients

OBJECTIVE

Several studies have shown increased oxidative stress in patients with pre-diabetes and newly diagnosed Type 2 diabetes mellitus (T2DM). It has been proposed that oxidative stress initiates insulin resistance in genetically predisposed individuals. The aim of this study was to evaluate the markers of oxidative stress in the offspring of patients with T2DM.

MATERIAL AND METHODS

We examined 60 lean normoglycemic offspring of Type 2 diabetics, and 52 age, sex and body mass index matched subjects without family history of T2DM as controls. Anthropometric, biochemical and carotid intima media thickness (IMT) measurements and oral glucose tolerance test (OGTT) were performed. Erythrocyte superoxide dismutase and glutathione peroxidase activities, serum nitric oxide, plasma total sulfhydryl (tSH) groups, plasma total antioxidant status, plasma malondialdehyde and serum 8-hydroxydeoxy-guanosine (8-OHdG) levels were compared between 2 groups.

RESULTS

2 groups were similar for the measurements of anthropometric, blood pressure, lipids, fasting glucose, HOMA-IR and carotid IMT. Glucose levels during OGTT were significantly higher in the offspring of Type 2 diabetics than controls (p=0.035). The offspring of Type 2 diabetics showed a significant increase in serum 8-OHdG level (p=0.005) and plasma tSH groups (p=0.032) when compared to the controls. Significant differences were not obtained in other oxidative stress marker levels between 2 groups.

CONCLUSION

Main finding of our study was the presence of increased oxidative DNA damage in lean normoglycemic offspring of Type 2 diabetic patients. There is a need for further clinical studies in order to explain whether oxidative stress is present in genetically predisposed subjects and induces the insulin resistance.

The relation of adiponectin and tumor necrosis factor alpha levels between endothelial nitric oxide synthase, angiotensin-converting enzyme, transforming growth factor beta, and tumor necrosis factor alpha gene polymorphism in adrenal incidentalomas

OBJECTIVE

The aim of our study was to demonstrate demographic characteristics, presence of inflammatory markers, distribution of angiotensin-converting enzyme (ACE), tumor necrosis factor (TNF), endothelial nitric oxide synthase (eNOS) genotypes and relations among these parameters in these patients and control subjects.

RESEARCH DESIGN AND METHODS

Study samples were collected from 50 patients with adrenal mass and 30 control groups. The eNOS, ACE, TNF-alpha, transforming growth factor (TGF)-beta genes polymorphisms, TNF-alpha, adiponectin levels were analysed in 50 unrelated Turkish patients with a diagnosis of adrenal incidentaloma (AI).

RESULTS

There was statistically significant difference between TNF-alpha levels of patient and controls (p=0.048). We have not detected the connection between TGF-beta, TNF-alpha, ACE, eNOS gene polymorphism with serum TNF-alpha and adiponectin levels. In this study, we demonstrated that there were significant differences for ACE genotypes in the patients when compared to the controls (p<0.05). The percentages of the ID, DD, II genotypes for ACE gene polymorphism in the patients group were 30.0, 13.0, 7.0%, respectively.

CONCLUSIONS

According to different cases of eNOS, TGF-beta, ACE, and TNF-alpha gene genotypes; no statistical significant difference was found between basal cortisol, ACTH, DHEAS, metanephrine, renin, aldosterone, normetanephrine, 17-hydroxyprogesterone, 1 mg low-dose dexamethasone suppression test-cortisol response and AI size. In this study, I/D genotype was determined to be statistically higher in ACE gene in patients with AI (p=0.014).

Complete remission of pulmonary spindle cell carcinoma after treatment with oral germanium sesquioxide

Spindle cell carcinoma (SCC) is a rare form of lung cancer representing 0.2 to 0.3% of all primary pulmonary malignancies. Even with combined surgery, chemotherapy, and radiation therapy, these tumors are associated with a poor prognosis and only 10% of patients survive 2 years after diagnosis. We describe a patient with an unresectable SCC who, following no response to conventional treatment with combined modality therapy, chose to medicate herself with daily doses of germanium obtained in a health food store. She noted prompt symptomatic improvement and remains clinically and radiographically free of disease 42 months after starting her alternative therapy.

The effect of Cys LT1 receptor blockade on airway responses to allergen

STUDY OBJECTIVE

To evaluate the effect of a potent experimental leukotriene receptor antagonist, MK-571, on airway responses to inhaled allergen.

DESIGN

Randomized, double-blind, placebo-controlled, crossover trial.

SETTING

Clinical research center.

SUBJECTS

Eight male volunteers with allergic asthma.

INTERVENTIONS

An intravenous loading dose was followed by an 8-hour infusion of MK-571 or placebo, with a 7- to 14-day washout between treatments. Allergen challenge was performed after the loading dose and a histamine challenge was performed before and 24 hours after allergen.

MEASUREMENTS AND MAIN RESULTS

Forced expiratory volume in 1 second was measured serially. MK-571 provided about 50% protection during maximum early and late responses compared with placebo (p=0.005), but airway obstruction persisted 8-24 hours after allergen on both treatment days. Airway responsiveness to histamine was not significantly attenuated at 24 hours.

CONCLUSION

Blocking Cys LT1 receptors for 8 hours attenuated the early and late responses but did not interrupt the cascade of events leading to subsequent allergen-induced airway obstruction and hyperreactivity.

Increased urinary excretion of LTE4 after exercise and attenuation of exercise-induced bronchospasm by montelukast, a cysteinyl leukotriene receptor antagonist

BACKGROUND

A study was undertaken to determine whether montelukast, a new potent cysteinyl leukotriene receptor antagonist, attenuates exercise-induced bronchoconstriction. The relationship between the urinary excretion of LTE4 and exercise-induced bronchoconstriction was also investigated.

METHODS

Nineteen non-smoking asthmatic patients with a forced expiratory volume in one second (FEV1) of > or = 65% of the predicted value and a reproducible fall in FEV1 after exercise of at least 20% were enrolled. Subjects received placebo and montelukast 100 mg once daily in the evening or 50 mg twice daily, each for two days, in a three-period, randomised, double blind, crossover design. In the evening, approximately 20-24 hours after the once daily dose or 12 hours after the twice daily dose, a standardised exercise challenge was performed. Data from 14 patients were available for complete analysis.

RESULTS

The mean (SD) maximal percentage decrease in FEV1 after exercise was 29.6 (16.0), 17.1 (8.2), and 14.0 (9.4) for placebo, once daily, and twice daily regimens, respectively. The mean (95% CI) percentage protection was 37 (15 to 59) for the group who received 50 mg twice daily and 50 (31 to 69) for those who received 100 mg once daily. Active treatments were not different from each other. The mean (SD) plasma concentrations of montelukast were higher after the twice daily regimen (1.27 (0.81) microgram/ml) than after the once daily regimen (0.12 (0.09) microgram/ml); there was no correlation between the percentage protection against exercise-induced bronchoconstriction and plasma concentrations. After exercise urinary excretion of LTE4 increased significantly during placebo treatment (from 34.3 to 73.7 pg/mg creatinine; p < 0.05) but did not correlate with the extent of exercise-induced bronchoconstriction.

CONCLUSIONS

Montelukast protects similarly against exercise-induced bronchoconstriction between plasma concentrations of 0.12 and 1.27 micrograms/ml. The increase in the urinary excretion of LTE4 after exercise and the protection from exercise-induced bronchoconstriction with a cysteinyl leukotriene receptor antagonist provide further evidence of the role of leukotrienes in the pathogenesis of exercise-induced bronchoconstriction.

Valproate-associated carnitine deficiency and malignant cerebral edema in the absence of hepatic failure

We describe a 27-year-old woman who developed encephalopathy and cerebral edema during treatment of refractory complex partial seizures that included acute administration of valproate (VPA) at a dosage of 35 mg/kg per day. Multiple random VPA levels were within therapeutic range, and results of liver function studies did not show evidence of hepatic failure. Cerebral computerized tomography (CT) showed evidence of massive cerebral edema with central herniation. Just prior to death, plasma levels of free and acyl carnitines were markedly decreased. Analysis of urinary organic acids showed increased excretion of lactate, but a normal distribution of VPA metabolites. Carnitine deficiency may predispose patients to the development of coma and life-threatening cerebral edema associated with acute administration of VPA, even in the absence of concomitant hepatic failure. We suggest specific guidelines for the evaluation and management of altered consciousness in patients with seizures receiving VPA.

Use of allergen bronchoprovocation to screen drugs for anti-asthma activity

In the atopic patient with asthma, allergens are an important cause of chronic airway inflammation and symptoms. Natural exposure to seasonal allergens, such as grass pollen, may result in exacerbation of asthma, increased airway responsiveness (i.e., increased susceptibility of the airways to constrict), and an increased frequency of emergency room visits. Removal of patients from exposure to indoor allergens, such as dust mites, results in a marked reduction in symptoms, less airway responsiveness, and a decrease in drug requirements. In the pulmonary function laboratory, inhalation of increasing doses of allergen, in a safe and controlled manner (allergen bronchoprovocation), produces physiological responses similar to those observed after natural exposure. These include an immediate decrease in the forced expiratory volume in 1 second (FEV1) that is rapid in onset but short in duration (early response), a subsequent gradual decline in FEV1 4-8 hours after allergen inhalation that is sustained (late response), an increase in airway responsiveness, and infiltration of the airway mucosa by inflammatory cells. Drugs that are effective as maintenance therapy for chronic asthma generally attenuate the late response to allergen bronchoprovocation, and those with antiinflammatory effects (e.g., inhaled corticosteroids) also attenuate the allergen-induced increase in airway responsiveness and cellular infiltration of the airways. However, the magnitude of drug effect in this clinical model does not correlate well with the drug's relative efficacy in chronic asthma. In contrast, drugs that have no effect in this clinical model, such as calcium channel blockers, ketotifen, and antihistamines, are ineffective as maintenance therapy for chronic asthma. Thus, it appears that allergen bronchoprovocation is most useful as a screening tool for excluding drugs that are unlikely to be effective for chronic asthma and for determining whether a drug has antiinflammatory and/or immunomodulatory actions on the airway mucosa.

Load carriage using packs: a review of physiological, biomechanical and medical aspects

This paper reviews the biomedical aspects of transporting loads in packs and offers suggestions for improving load-carriage capability. Locating the load mass as close as possible to the body center of gravity appears to result in the lowest energy cost when carrying a pack. Thus, the double pack (half the load on the front of the body and half the load on the back) has a lower energy cost than the backpack. However, backpacks provide greater versatility in most situations. The energy cost of walking with backpack loads increases progressively with increases in load mass, body mass, walking speed or grade; type of terrain also influences energy cost. Predictive equations have been developed for estimating the energy cost of carrying loads during locomotion but these may not be accurate for prolonged (>2 h) or downhill carriage. Training with loads can result in greater energy efficiency since walking with backpack loads over several weeks decreases energy cost. Load-carriage speed can be increased with physical training that involves regular running and resistance training. Erector spinae electrical activity (EMG) is lower during load carriage than in unloaded walking until loads exceed 30-40 kg, at which point erector spinae EMG activity is higher than during unloaded walking. EMGs of the quadriceps and gastrocnemius, but not the tibialis anterior or hamstrings, increase with load. Framed packs with hip belts reduce the electrical activity of the trapezius muscles, presumably by shifting forces from the shoulders to the hips. Increases in the backpack load mass result in increases in forces exerted on the grounds, amount of knee flexion and the forward inclination of the trunk. Compared to backpacks, double packs produce fewer deviations from normal walking. Common injuries associated with prolonged load carriage include foot blisters, stress fractures, back strains, metatarsalgia (foot pain), rucksack palsy (shoulder traction injury) and knee pain. Closed-cell neoprene insoles and use of an acrylic or nylon sock, combined with a wool sock, reduce blister incidence. A framed pack with a hip belt reduces the incidence of rucksack palsy. Backpack load carriage can be facilitated by lightening loads, optimizing equipment, improving load distribution and by preventive action aimed at reducing the incidence of injury.

Theophylline attenuation of airway responses to allergen: comparison with cromolyn metered-dose inhaler

BACKGROUND

The purpose of this study was to compare the protection afforded by individualized doses of theophylline and a cromolyn metered-dose inhaler (MDI) during allergen challenge.

METHODS

The study design was randomized, double-blind, and crossover. Responses to inhaled allergen were measured in 16 subjects with allergic asthma (age range, 18 to 35 years) after 7 days of treatment with either placebo, once daily slow-release theophylline producing a mean +/- SD serum concentration of 16 +/- 5 micrograms/ml during the late phase, or 2 mg of cromolyn administered by MDI four times daily. Forced expiratory volume in 1 second was measured at frequent intervals, and airway responsiveness to histamine was measured before and 3 hours after allergen challenge.

RESULTS

The mean +/- SD maximum decrease in forced expiratory volume in 1 second during the late phase was 30% +/- 14% during placebo treatment, 16% +/- 13% during theophylline treatment, and 13% +/- 14% during cromolyn treatment (placebo vs theophylline and cromolyn, p = 0.0001; theophylline vs cromolyn, p = 0.1). The geometric mean fold increase in airway responsiveness was 3.0 +/- 1.7 during placebo treatment, 1.7 +/- 1.7 during theophylline treatment, and 1.5 +/- 1.6 during cromolyn treatment (placebo vs theophylline and cromolyn, p = 0.0001; theophylline vs cromolyn, p = 0.1).

CONCLUSIONS

Theophylline, when administered once daily as a slow-release formulation, was as effective as cromolyn, administered four times daily through an MDI, in attenuating airway responses to inhaled allergen. The protection afforded by both treatments, however, was modest when compared with the results of similar studies with inhaled corticosteroids or other cromolyn formulations that deliver more drug to the lungs than the MDI available in the United States.

Therapeutic equivalence of a generic slow-release theophylline tablet

STUDY OBJECTIVE

To evaluate the relative bioavailability and clinical efficacy of two slow-release theophylline products.

DESIGN

Randomized, double-blind, crossover trial.

SETTING

A university-affiliated clinical research center.

PATIENTS

Fourteen adults with asthma.

INTERVENTIONS

The patients received a generic slow-release theophylline tablet or Theo-Dur at bedtime for 5 nights.

MEASUREMENTS AND MAIN RESULTS

Serum drug concentrations were measured after the last dose. Attenuation of exercise-induced bronchospasm (EIB) was included as a surrogate for efficacy. There was no significant difference in extent of absorption. The mean differences between the generic product and Theo-Dur in area under the curve was -13.9 micrograms/ml.hr-1 (95% CI -41 to 12.9, p = 0.3) and in peak concentration (Cmax), -0.5 microgram/ml (95% CI -1.7 to 2.7, p = 0.6). In contrast, the generic product was absorbed more rapidly; the mean differences in the time to peak concentration (Tmax) was -3.0 hours (95% CI -4.3 to -1.7, p = 0.0003), in trough concentration (Cmin), -0.9 microgram/ml (95% CI -1.9 to -0.01, p = 0.05), and in fluctuation between Cmax and Cmin, +128% (95% CI 40 to 217, p = 0.008). Neither product effectively attenuated EIB, since mean serum concentrations during the exercise challenges were unexpectedly below 10 micrograms/ml after both products.

CONCLUSION

These two products are not bioequivalent, but the difference in absorption rates is unlikely to be clinically important in most patients (i.e., they are therapeutic equivalents).

Does aminophylline benefit adults admitted to the hospital for an acute exacerbation of asthma?

OBJECTIVE

To determine the effect of adding intravenous theophylline (administered as aminophylline) to nebulizations of albuterol and intravenous methylprednisolone in adults hospitalized for acute asthma.

DESIGN

Randomized, placebo-controlled, double-blind study.

SETTING

Inpatient service of a tertiary-care, university teaching hospital.

PATIENTS

21 adults (22 to 48 years old)--10 in the aminophylline group and 11 in the placebo group.

INTERVENTIONS

Nebulized albuterol, 2.5 or 5.0 mg every 0.5 to 4 hours; intravenous methylprednisolone, 60 mg every 6 hours; and either individualized doses of aminophylline or placebo for 48 hours.

MEASUREMENTS

Forced expiratory volume in 1 second (FEV1), the number of "as needed" albuterol nebulizations and total dose, asthma symptom scores, and adverse effects.

RESULTS

At admission from the emergency department, the mean +/- SD baseline FEV1 was 49% +/- 19% of the predicted value in the aminophylline group and 43% +/- 13% of the predicted value in the placebo group. The improvement in FEV1 at 3 hours was greater in the aminophylline group (29% +/- 23% compared with 10% +/- 10% in the placebo group; mean difference, 19 percentage points; 95% CI, 3 to 35 percentage points; P = 0.023). At 48 hours, FEV1 was 75% +/- 19% of the predicted value in the aminophylline group and 58% +/- 15% of the predicted value in the placebo group (mean difference, 17 percentage points; CI, 0.2 to 34.8 percentage points; P = 0.048). Aminophylline-treated patients required fewer nebulizations of albuterol (10.3 +/- 3.8 compared with 16.4 +/- 5.3; mean difference, -6.1; CI, -10.3 to -1.8) and less total dosage (34 +/- 16 mg compared with 70 +/- 34 mg; mean difference, -36 mg; CI, -60.6 to -11.3 mg P = 0.02). No statistical differences were observed in asthma symptom scores or frequency of adverse effects.

CONCLUSIONS

Individualized doses of intravenous theophylline added to frequent nebulizations of albuterol and intravenous methylprednisolone appear to benefit adults admitted to the hospital with acute asthma and are well tolerated when serum concentrations are maintained in the therapeutic range.

The effect of inhaled gallopamil, a potent calcium channel blocker, on the late-phase response in subjects with allergic asthma

The effect of gallopamil on the late-phase response to inhaled allergen was evaluated in six young adults with allergic asthma in a crossover manner. During 2 study days, subjects received 20 mg of inhaled gallopamil or placebo 30 minutes before challenge with the same dose of allergen. In addition, a histamine challenge was performed 1 1/2 hours before and 24 hours after allergen challenge. On 2 additional study days, in the absence of allergen, basal airway responsiveness to histamine was measured before and after gallopamil or placebo administration. During the early phase, the mean +/- SD decrease in FEV1 was 28.0% +/- 11.3% after placebo and 25.1% +/- 8.4% after gallopamil administration (p greater than 0.05; beta = 0.14). During the late phase, the maximum decrease in FEV1 was 26.9% +/- 11.9% after placebo and 25.3% +/- 10.3% after gallopamil administration (p greater than 0.05; beta = 0.21). Airway reactivity to histamine 24 hours after allergen challenge could not be measured in three subjects after gallopamil administration and in one subject after placebo administration because of persistent bronchospasm. In contrast, basal responsiveness to histamine in the absence of allergen was modestly decreased by gallopamil. Since gallopamil is one of the most potent calcium channel blockers when it is administered by the inhaled route, it is unlikely that this group of drugs will be clinically useful for allergic asthma.

Evaluation of a generic albuterol metered-dose inhaler: importance of priming the MDI

Since the patent on albuterol metered-dose inhalers (MDI) expired in 1989, several manufacturers have developed generic products. In order to determine whether one generic albuterol MDI is equivalent to a reference product (Ventolin MDI), we compared the relative efficacy of two puffs (180 micrograms) of each inhaler in 17 intermittent or mild chronic adult asthmatics (FEV1 48% to 77% predicted) in a randomized, single-blind, crossover manner. The test dose was the first two puffs out of each canister. Pulmonary function was measured before each test dose and at frequent intervals over eight hours. Baseline FEV1 values on both study days were within 20%. The mean +/- SD peak effect was 80.5 +/- 15.5% of maximum achievable improvement in FEV1 after the generic compared with 92.2 +/- 8.8% after Ventolin (P = .006). The area under the curve (AUC) for this same measurement during the first four hours was 242 +/- 75%.hr-1 after the generic compared with 297 +/- 40%.hr-1 after Ventolin, a mean difference of 19% (P = .002). The study was then repeated with the MDI primed prior to the test dose (ie, two puffs were first discharged into a waste basket) in subjects willing to return for re-study (n = 11). There was no significant difference in AUC in the second study: 215 +/- 77%.hr-1 after generic and 228 +/- 82%.hr-1 after Ventolin (P = .65); however, there was only a 35% chance of detecting a 20% difference in AUC with this sample size. These data indicate that, without priming, an MDI may deliver less drug, and thereby less therapeutic effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Relative amount of albuterol delivered to lung receptors from a metered-dose inhaler and nebulizer solution. Bioassay by histamine bronchoprovocation

The results of previous studies comparing bronchodilatation from beta agonists administered by metered-dose inhaler (MDI) and nebulizer solution have been conflicting. We therefore evaluated a range of albuterol doses administered by these two methods, using histamine bronchoprovocation as a bioassay for the amount of drug reaching the beta 2 receptors in the lung. Twelve stable asthmatic volunteers received, in a double-blind, randomized, crossover design on different days, placebo or one, two, four, or six puffs from an MDI attached to an InspirEase device (90 micrograms per puff) or 0.625, 1.25, 2.5, or 5.0 mg of solution delivered in 2 ml of buffered saline through a Hudson Updraft II nebulizer. The histamine concentration required to decrease FEV1 by 20 percent (PC20) was measured 1 h before and 30 min after administration of each treatment and expressed as the increase in PC20 from baseline. The dose-response curves for change in PC20 indicated that the higher doses of the nebulizer solution delivered more drug to beta 2 receptors in the lung than the lower doses from the MDI. For example, the geometric mean increase in PC20 was 1.1 +/- 1.6 (SD) after placebo, 7.5 +/- 2.7 after two puffs from the MDI, and 20.0 +/- 2.1 after 2.5 mg of nebulizer solution (p less than 0.05). Using this bioassay method and administration technique, we estimated that ten puffs from the MDI (0.9 mg) would deliver approximately the same amount of albuterol to lung receptors as 2.5 mg of the nebulizer solution. Taking into account previously published reports and the results of the present study, we conclude that differences in dose, administration technique, nebulizer system efficiency, and severity of airway obstruction can alter the amount of drug reaching the beta 2 receptors in the lungs and, thus, the clinical response.

Inhaled verapamil-induced bronchoconstriction in mild asthma

Methacholine challenges were performed in ten subjects with mild asthma at 2 h before and 20 min after placebo or 5, 10, 20, 40, 80, and 160 mg of inhaled verapamil given in a single-blind randomized crossover manner on different days. While verapamil did not have a bronchodilator effect, the 10-mg dose modestly increased the concentration of methacholine required to decrease FEV1 by 20 percent (PC20). The mean (+/- SEM) increase in PC20 from baseline was 2.1 +/- 0.2 times baseline after 10 mg of verapamil, compared to 1.1 +/- 0.1 times baseline after placebo (p less than 0.001). Unexpectedly, bronchoconstriction (greater than 10 percent decrease in FEV1) associated with cough or wheezing was observed in seven of ten subjects at doses of 20 mg or more. This adverse effect was not related to the osmolarity of the nebulized solutions. Thirty minutes before a standardized exercise challenge, 13 subjects inhaled placebo, 10 mg, or the highest dose of verapamil tolerated during the methacholine study (20 to 160 mg) in a double-blind randomized crossover manner. The exercise challenge was aborted in three subjects because of bronchospasm that occurred after administration of the higher dose. The mean (+/- SEM) maximum change in FEV1 after exercise in the ten subjects completing all three regimens of treatment was -17.1 +/- 4.0 percent after placebo, -12.7 +/- 4.3 percent after 10 mg (p less than 0.05), and -6.4 +/- 3.6 percent after the highest dose (p less than 0.05). We conclude that increasing the dose of verapamil above 10 mg did not provide greater benefit but, paradoxically, induced bronchoconstriction in most of the subjects. Because of this potential bronchoconstrictor effect, high doses of oral or intravenous verapamil should be used with caution in asthmatic subjects.

Endogenous anabolic hormonal and growth factor responses to heavy resistance exercise in males and females

To examine endogenous anabolic hormonal responses to two different types of heavy resistance exercise protocols (HREPs), eight male and eight female subjects performed two randomly assigned protocols (i.e. P-1 and P-2) on separate days. Each protocol consisted of eight identically ordered exercises carefully designed to control for load, rest period length, and total work (J) effects. P-1 utilized a 5 RM load, 3-min rest periods and had lower total work than P-2. P-2 utilized a 10 RM load, 1-min rest periods and had a higher total work than P-1. Whole blood lactate and serum glucose, human growth hormone (hGH), testosterone (T), and somatomedin-C [SM-C] (i.e. insulin-like growth factor 1, IGF-1) were determined pre-exercise, mid-exercise (i.e. after 4 of the 8 exercises), and at 0, 5, 15, 30, and 60 min post-exercise. Males demonstrated significant (p less than 0.05) increases above rest in serum T values, and all serum concentrations were greater than corresponding female values. Growth hormone increases in both males and females following the P-2 HREP were significantly greater at all time points than corresponding P-1 values. Females exhibited significantly higher pre-exercise hGH levels compared to males. The P-1 exercise protocol did not result in any hGH increases in females. SM-C demonstrated random significant increases above rest in both males and females in response to both HREPs.(ABSTRACT TRUNCATED AT 250 WORDS)

Hormonal and growth factor responses to heavy resistance exercise protocols

To examine endogenous anabolic hormone and growth factor responses to various heavy resistance exercise protocols (HREPs), nine male subjects performed each of six randomly assigned HREPs, which consisted of identically ordered exercises carefully designed to control for load [5 vs. 10 repetitions maximum (RM)], rest period length (1 vs. 3 min), and total work effects. Serum human growth hormone (hGH), testosterone (T), somatomedin-C (SM-C), glucose, and whole blood lactate (HLa) concentrations were determined preexercise, midexercise (i.e., after 4 of 8 exercises), and at 0, 5, 15, 30, 60, 90, and 120 min postexercise. All HREPs produced significant (P less than 0.05) temporal increases in serum T concentrations, although the magnitude and time point of occurrence above resting values varied across HREPs. No differences were observed for T when integrated areas under the curve (AUCs) were compared. Although not all HREPs produced increases in serum hGH, the highest responses were observed consequent to the H10/1 exercise protocol (high total work, 1 min rest, 10-RM load) for both temporal and time integrated (AUC) responses. The pattern of SM-C increases varied among HREPs and did not consistently follow hGH changes. Whereas temporal changes were observed, no integrated time (AUC) differences between exercise protocols occurred. These data indicate that the release patterns (temporal or time integrated) observed are complex functions of the type of HREPs utilized and the physiological mechanisms involved with determining peripheral circulatory concentrations (e.g., clearance rates, transport, receptor binding). All HREPs may not affect muscle and connective tissue growth in the same manner because of possible differences in hormonal and growth factor release.

Pentamidine-induced torsades de pointes in a renal transplant recipient with Pneumocystis carinii pneumonia

Pentamidine isethionate, an important agent used to treat Pneumocystis carinii pneumonia, has been shown to be associated with the development of torsades de pointes in patients with AIDS. We have described a case of pentamidine-induced polymorphous ventricular tachycardia in a renal transplant recipient whose renal insufficiency may have prolonged the duration of arrhythmias. Careful ECG monitoring should be done during pentamidine administration, especially in patients with renal insufficiency. Physicians should be aware that this variety of polymorphous ventricular tachycardia can occur well within the recommended dose of pentamidine. More data are needed to define the relationship between renal dysfunction, plasma levels, and pentamidine cardiotoxicity.

Clinical relevance of the interaction of theophylline with diltiazem or nifedipine

The results of previously published studies indicate that calcium channel blockers are capable of competitively inhibiting cytochrome P-450 activity in hepatic microsomes, the pathway of theophylline metabolism. In addition, case reports have suggested that theophylline serum concentrations change when a calcium channel blocker has been added to or deleted from a stable theophylline regimen. To determine the clinical relevance of this potential interaction in patients with chronic asthma, we measured a peak steady-state theophylline serum concentration in 21 subjects while receiving theophylline alone (400 to 1,500 mg/day), and again, at least seven days later, after the addition of continuous therapy with maximally tolerated doses of either diltiazem (n = 18) or nifedipine (n = 16). The diltiazem dose was increased in 120 mg/day increments, as tolerated, to a maximum of 240 to 480 mg/day, while the nifedipine dose was increased in increments of 40 mg/day, to a maximum dose of 80 to 160 mg/day. The mean +/- SEM theophylline serum concentrations were 13.6 +/- 1.4 micrograms/ml before and 14.0 +/- 1.2 micrograms/ml during concurrent diltiazem therapy, and 12.6 +/- 1.0 micrograms/ml before and 12.2 +/- 1.1 micrograms/ml during nifedipine (p greater than 0.05). With this sample size there is a 5 percent chance that we missed a 20 percent change in serum concentration (type II error). Thus, maximum tolerated doses of diltiazem or nifedipine do not impair the metabolism of theophylline to a clinically relevant degree and adjustment of theophylline dosage is not required after the addition or discontinuation of diltiazem or nifedipine. In addition, these data suggest that currently available in vitro techniques for evaluating drug interactions in the hepatocyte do not predict the clinical relevance of such an interaction in patients who might require both drugs for different therapeutic indications.

Hypothalamic-pituitary-adrenal responses to short-duration high-intensity cycle exercise

beta-Endorphin (beta-EP), adrenocorticotropin (ACTH), and cortisol plasma concentrations were examined before and after maximal exercise at four intensities [36, 55, 73, and 100% of maximal leg power (MLP)] by means of a computerized cycle ergometer. All intensities were greater than those eliciting peak O2 uptake for the individual subjects. Blood samples were collected at rest, immediately after exercise, and at 5 and 15 min postexercise. Significant (P less than 0.05) increases were observed at 36% MLP for beta-EP and ACTH immediately after exercise and at 5 and 15 min postexercise. Plasma cortisol increased at 36% MLP at 15 min postexercise. Blood lactate significantly increased at all postexercise collection points for exercise intensities of 36, 55, and 73% MLP and at 5 min postexercise for 100% MLP. beta-EP concentrations at 36% MLP were significantly correlated (r = 0.75) with capillary density (mm-2), and cortisol concentrations at 36% MLP were significantly correlated (r = 0.89) with percentage of type II muscle fibers. No other significant relationships were observed. These data show that brief, high-intensity exercise up to maximal power production results in a nonlinear response pattern in peripheral blood hormone concentrations. Furthermore, blood lactate levels do not appear to be related to hypothalamic-pituitary-adrenal hormone plasma concentrations at high exercise intensities.

The effects of nalmefene, a potent oral opiate antagonist, on exercise-induced bronchospasm

Endogenous opioids are released during exercise and have been demonstrated to induce mast cell degranulation when they are administered intradermally. Thus, these peptides may play a role in the pathogenesis of exercise-induced bronchospasm (EIB). However, in two previous studies, intravenous naloxone did not provide significant protection from EIB. To determine if these failures were due to inadequate dosage (pharmacokinetic failure) or lack of an inherent pharmacologic effect (pharmacodynamic failure), the present study was conducted with nalmefene (Key Pharmaceuticals, Inc., Miami, Fla.), a slowly metabolized, orally bioavailable opiate antagonist, with 30 times the potency of naloxone. Ten subjects with mild intermittent asthma and a greater than or equal to 20% decrease in FEV1 after a standardized exercise test were studied. nalmefene, 20 mg, and identically appearing placebo tablets were administered orally in a double-blind, randomized, crossover design 2 hours before bronchoprovocation. Treadmill exercise was performed for 6 minutes at a minute ventilation of 55% to 66% of the calculated maximum voluntary ventilation and not exceeding 75% to 85% maximal heart rate for age. Spirometry was performed before and 3, 5, 8, 10, and 15 minutes after exercise. The mean decrease in FEV1 after exercise was 28.6 +/- 4.5% with placebo and 30.3 +/- 4.5% with Nalmefene (p = 0.6; beta = 0.04 for a 15% difference). Thus, we conclude that narcotic antagonists do not alter airway reactivity to exercise. In addition, these data suggest that endogenous opioids probably do not play an important role in the pathogenesis of EIB.

Maximal aerobic capacity for repetitive lifting: comparison with three standard exercise testing modes

A multi-stage, repetitive lifting maximal oxygen uptake (VO2max) test was developed to be used as an occupational research tool which would parallel standard ergometric VO2max testing procedures. The repetitive lifting VO2max test was administered to 18 men using an automatic repetitive lifting device. An intraclass reliability coefficient of 0.91 was obtained with data from repeated tests on seven subjects. Repetitive lifting VO2max test responses were compared to those for treadmill, cycle ergometer and arm crank ergometer. The mean +/- SD repetitive lifting VO2max of 3.20 +/- 0.42 l.min-1 was significantly (p less than 0.01) less than treadmill VO2max (delta = 0.92 l.min-1) and cycle ergometer VO2max (delta = 0.43 l.min-1) and significantly greater than arm crank ergometer VO2max (delta = 0.63 l.min-1). The correlation between repetitive lifting oxygen uptake and power output was r = 0.65. VO2max correlated highly among exercise modes, but maximum power output did not. The efficiency of repetitive lifting exercise was significantly greater than that for arm cranking and less than that for leg cycling. The repetitive lifting VO2max test has an important advantage over treadmill or cycle ergometer tests in the determination of relative repetitive lifting intensities. The individual curves of VO2 vs. power output established during the multi-stage lifting VO2max test can be used to accurately select work loads required to elicit given percentages of maximal oxygen uptake.

Duration of effect of gallopamil, a calcium channel blocker, on methacholine-induced bronchoconstriction

We previously demonstrated a modest but significant protective effect of inhaled gallopamil (D600), the methoxy derivative of verapamil, against methacholine-induced bronchoconstriction; however, the duration of the protective effect of this and other calcium channel blockers is unknown. We therefore evaluated the duration of this protective effect in 15 asthmatic subjects in a prospective, placebo-controlled trial. Methacholine challenges (Cockcroft method) were performed 2 hours before and 30 minutes after the administration of placebo, and 1 mg and 10 mg of inhaled gallopamil. Gallopamil did not alter resting airway caliber, but significantly increased the concentration of methacholine required to decrease the FEV1 20% 30 minutes after the dose. Results with both the 10-mg and 1-mg doses were significantly different from placebo, but not from each other. The duration of this protective effect was transient in the group as a whole; the mean drug activity ratios were not significantly different with this sample 2.5 hours after the dose. Thus the short duration of effect limits the potential clinical usefulness of gallopamil in suppressing the signs and symptoms of chronic asthma.

Dose response of inhaled gallopamil (D600), a calcium channel blocker, in attenuating airway reactivity to methacholine and exercise

To determine if there is a dose-response relationship for calcium channel blockers in preventing experimentally induced bronchoconstriction, we evaluated the effects of inhaled gallopamil (D600), a potent methoxy derivative of verapamil, on airway reactivity to methacholine and exercise in volunteers with mild asthma. Methacholine challenges were completed by 11 subjects 2 hours before and 20 minutes after placebo, and 1, 2, 5, 10, and 20 mg of inhaled gallopamil administered in a single-blind, randomized manner on different days. Gallopamil did not significantly alter FVC, FEV1, or forced expiratory flow rate between 25% and 75% of FVC, but increased the dose of methacholine required to produce a 20% decrease in FEV1 from baseline (p less than 0.0001). The mean +/- SEM fold increase in the dose of methacholine required to produce a 20% decrease in FEV1 from baseline was 1.0 +/- 0.1 after placebo, 2.4 +/- 0.2 after 1 mg, 2.2 +/- 0.2 after 2 mg, 2.5 +/- 0.2 after 5 mg, 2.5 +/- 0.3 after 10 mg, and 2.3 +/- 0.2 after 20 mg. Thirty minutes before a standardized exercise challenge, 10 subjects inhaled 1 and 10 mg of gallopamil or placebo in a randomized, double-blind, crossover manner. The mean +/- SEM maximum decrease in FEV1 after exercise was 25.1 +/- 5% after 10 mg of gallopamil (p less than 0.01), 34.4 +/- 5% after 1 mg (p greater than 0.05), and 39.0 +/- 6% after placebo. We conclude that inhaled gallopamil only modestly alters airway reactivity to methacholine; increasing the dose greater than 1 mg did not provide greater benefit.(ABSTRACT TRUNCATED AT 250 WORDS)