CONTINUOUS MONITORING OF THE GALVANIC SKIN RESPONSE

poster abstractGalvanic Skin Response (GSR) is an objective measurement of the electrical conductance of the skin. GSR is tightly correlated with peripheral sweat rate, which in turn is associated with many clinical conditions. These conditions include, but are not limited to, menopausal “hot flashes”, diabetic hypoglycemic and hyperglycemic episodes, and various cancers. The objective quantification of GSR can be a valuable clinical tool in evaluating the effectiveness of clinical interventions for these and other conditions. Current methods of monitoring GSR are not well suited to implementation outside of the clinical setting. The goal of this research is to develop a reliable portable device for real-time ambulatory monitoring of GSR. In order to get accurate and consistent readings, electrodes must be attached to the patient with a lasting and non-irritating electrically conductive gel with suitable impedance characteristics. Development of such a device requires consideration of many physiological factors. The distribution and density of sweat glands must be considered to determine a location for the device on the body that will yield measurable GSR without interfering with the patient’s daily activities. We are in the process of evaluating the electrical impedance of electrode and gel combinations presently used in the Carpenter lab. Quantification of the frequency dependent loading profile of the electrode-gel interface will improve the measurement accuracy of the GSR. The ionic composition of sweat and the sweat rate must be evaluated to ensure that the integrity of the interface between the body and the device is maintained throughout the monitoring period. 1Department of Biomedical Engineering, Purdue School of Engineering and Technology, Indiana University-Purdue University Indianapolis, IN 46204 2Center for Enhancing Quality of Life, Indiana University School of Nursing, IUPUI, Indianapolis, IN 4620

ROLE OF SWEAT GLAND PHYSIOLOGY IN OBJECTIVE GALVANIC SKIN RE-SPONSE MEASUREMENT

poster abstractFor the purpose of studying sweat in response to hot flashes, a type of thermal sweating, the process of extensive literature review performed in this particular project focused primarily on the eccrine sweat glands. Of the three categories of sweat glands, eccrine sweat glands account for the ma-jority of the sweat glands on the human body, existing over almost the en-tire body surface, and contributing to thermal sweating. Thermal sweating occurs as a means for the human body to regulate temperature (Johnson 1996). There are approximately 1.6 to 5 million eccrine sweat glands dis-tributed over the surface of the human body. Sweat gland density varies across different regions of the body, with the highest density on the palms of hands and soles of feet, while the lowest sweat gland density of 64 sweat glands per square centimeter is found on the back (Wilke et al., 2007). Wa-ter comprises approximately 99% of eccrine sweat, with the remaining com-pounds consisting mostly of varying amounts of sodium, potassium, calcium, and magnesium (Groscurth, 2002). The Galvanic Skin Response is an objec-tive measure of skin conductance that has been linked with the peripheral sweat rate (Carpenter et al., 2005). Importance has been put upon the po-tential clinical significance of using the Galvanic Skin Response to objectively enumerate the influence and effectiveness of interventions for health related issues in which sweating is a substantial symptom (Tataryn et al., 1981). One of the objectives of this research is to determine the effect that various sweat gland physiological factors, such as density, ionic composition, and sweat rate, may have on the accuracy of different Galvanic Skin Response measurement techniques and devices. 1Center for Enhancing Quality of Life, Indiana University School of Nursing, IUPUI, Indian-apolis, IN 4620

Natural progression of childhood asthma symptoms and strong influence of sex and puberty.

Rationale: Asthma prevalence, onset, remission and relapse, and healthcare use have been intensively studied. However, asthma symptom progression through childhood and adolescence has not been well studied, in part due to the challenges in obtaining consistent and robust long-term follow-up data on a large series of subjects with asthma. Objectives: To use the asthma diary symptom data of the Childhood Asthma Management Program placebo group (5 yr, 418 subjects, and total 564,518 records) to establish sex-specific high-resolution time courses of the natural progression of asthma symptoms through childhood and adolescence. Methods: We used the asthma diary symptom code as a measure of daily disease severity. Annual records of Tanner stage were used to determine the influence of puberty on severity. A data alignment technique was used to derive 13-year time courses of mean symptoms and mean Tanner stage. Measurements and Main Results: Data analyses showed three age- and sex-related phases of asthma symptom progression: Phase 1 (ages 5 and 6 yr)—greater severity in boys; Phase 2 (ages 7 to 9 yr)—no sex difference in severity; and Phase 3 (age 10-17 yr)—greater severity in girls. The continuous decline of symptoms in both sexes stops abruptly at the onset of puberty. Conclusions: The severity of asthma symptoms varies through childhood and adolescence, and patterns differ by sex. Puberty has a strong influence on symptom progression in both sexes. Progression of symptoms is a distinct aspect of asthma epidemiology

Genetic influences on vitamin d status and forearm fracture risk in african american children

We sought to investigate the relationship between newly identified genetic variants and vitamin D levels and fracture risk in healthy African American (black) children. This case-control study included children of both sexes, ages 5 to 9 years, with and without forearm fractures. Serum 25-hydroxy vitamin D levels, bone mineral density, body mass index, and calcium/vitamin D intake were measured in 130 individuals (n = 60 cases and n = 70 controls). The 5 variants tested were located in the GC gene (rs2282679), in the NADSYN1 gene (rs12785878 and rs3829251), and in the promoter region of the CYP2R1 gene (rs2060793 and rs104741657). Associations between single nucleotide polymorphisms (SNPs) and vitamin D levels were tested using an analysis of covariance. Associations between SNPs and fracture status were tested using logistic regression. The GC gene variant was associated with vitamin D levels (P = 0.038). None of the SNPs were associated with fracture status in young blacks. These results suggest that the variants tested, which are associated with circulating vitamin D levels in whites, are not associated with fracture status in healthy black children. Additional research is required to discover the genetics of fracture risk in blacks. Copyright © 2012 by The American Federation for Medical Research

Genetic influences on vitamin D status and forearm fracture risk in African American children

We sought to investigate the relationship between newly identified genetic variants and vitamin D levels and fracture risk in healthy African American (black) children. This case-control study included children of both sexes, ages 5 to 9 years, with and without forearm fractures. Serum 25-hydroxy vitamin D levels, bone mineral density, body mass index, and calcium/vitamin D intake were measured in 130 individuals (n = 60 cases and n = 70 controls). The 5 variants tested were located in the GC gene (rs2282679), in the NADSYN1 gene (rs12785878 and rs3829251), and in the promoter region of the CYP2R1 gene (rs2060793 and rs104741657). Associations between single nucleotide polymorphisms (SNPs) and vitamin D levels were tested using an analysis of covariance. Associations between SNPs and fracture status were tested using logistic regression. The GC gene variant was associated with vitamin D levels (P = 0.038). None of the SNPs were associated with fracture status in young blacks. These results suggest that the variants tested, which are associated with circulating vitamin D levels in whites, are not associated with fracture status in healthy black children. Additional research is required to discover the genetics of fracture risk in blacks. Copyright © 2012 by The American Federation for Medical Research

Sex differences in the association between neck circumference and asthma.

INTRODUCTION: The association between obesity and asthma control/quality of life commonly relies on body mass index (BMI) as the anthropomorphic measure. Due to limitations of BMI and the existence of alternative measures, such as neck circumference (NC), we examined the association between NC and asthma control/quality of life, with particular attention to male–female differences MATERIALS AND METHODS: The AsthMaP-2 Project is an observational study of youth with physician–diagnosed asthma. NC was stratified according to age- and sex-specific cutoffs and associated with asthma control (via Asthma Control Test [ACT]) and quality of life (via Integrated Therapeutics Group [ITG]—Asthma Short Form) RESULTS: The mean±SD age was 11.9±3.6 years, and 53% were male (N=116). The mean BMI percentile was at the 71±28 percentile. Thirty-one participants (27%) met criteria for high NC. Males with high NC had significantly worse asthma control (P =0.02) and lower quality of life than those with low NC. No similar association was found for females and the proportion of variability in ACTand ITG was best explained by BMI percentile. Conversely, for males, the proportion of variability in these scores explained by NC was larger than BMI percentile alone (Cohen’s f(2) =0.04–0.09, a small to medium effect size) DISCUSSION: Among male youth with asthma, combined use of NC and BMI percentile explained asthma control and quality of life better than BMI alone. Future studies of asthma should include measurement of NC and other anthropogenic measures of regional adiposity to clarify sex differences in asthma

Can we predict fall asthma exacerbations? Validation of the seasonal asthma exacerbation index

BACKGROUND: A Seasonal Asthma Exacerbation Predictive Index (saEPI) was previously reported based on 2 prior National Institute of Allergy and Infectious Diseases Inner City Asthma Consortium trials. OBJECTIVE: This study sought to validate the saEPI in a separate trial designed to prevent fall exacerbations with omalizumab therapy. METHODS: The saEPI and its components were analyzed to characterize those who had an asthma exacerbation during the Preventative Omalizumab or Step-Up Therapy for Fall Exacerbations (PROSE) study. We characterized those inner-city children with and without asthma exacerbations in the fall period treated with guidelines-based therapy (GBT) in the absence and presence of omalizumab. RESULTS: A higher saEPI was associated with an exacerbation in both the GBT alone (P \u3c .001; area under the curve, 0.76) and the GBT + omalizumab group (P \u3c .01; area under the curve, 0.65). In the GBT group, younger age at recruitment, higher total IgE, higher blood eosinophil percentage and number, and higher treatment step were associated with those who had an exacerbation compared with those who did not. In the GBT + omalizumab group, younger age at recruitment, increased eosinophil number, recent exacerbation, and higher treatment step were also associated with those who had an exacerbation. The saEPI was associated with a high negative predictive value in both groups. CONCLUSIONS: An exacerbation in children treated with GBT with or without omalizumab was associated with a higher saEPI along with higher markers of allergic inflammation, treatment step, and a recent exacerbation. Those that exacerbated on omalizumab had similar features with the exception of some markers of allergic sensitization, indicating a need to develop better markers to predict poor response to omalizumab therapy and alternative treatment strategies for children with these risk factors. The saEPI was able to reliably predict those children unlikely to have an asthma exacerbation in both groups

Can we predict fall asthma exacerbations? Validation of the seasonal asthma exacerbation index.

BACKGROUND: A Seasonal Asthma Exacerbation Predictive Index (saEPI) was previously reported based on 2 prior National Institute of Allergy and Infectious Diseases Inner City Asthma Consortium trials. OBJECTIVE: This study sought to validate the saEPI in a separate trial designed to prevent fall exacerbations with omalizumab therapy. METHODS: The saEPI and its components were analyzed to characterize those who had an asthma exacerbation during the Preventative Omalizumab or Step-Up Therapy for Fall Exacerbations (PROSE) study. We characterized those inner-city children with and without asthma exacerbations in the fall period treated with guidelines-based therapy (GBT) in the absence and presence of omalizumab. RESULTS: A higher saEPI was associated with an exacerbation in both the GBT alone (P \u3c .001; area under the curve, 0.76) and the GBT + omalizumab group (P \u3c .01; area under the curve, 0.65). In the GBT group, younger age at recruitment, higher total IgE, higher blood eosinophil percentage and number, and higher treatment step were associated with those who had an exacerbation compared with those who did not. In the GBT + omalizumab group, younger age at recruitment, increased eosinophil number, recent exacerbation, and higher treatment step were also associated with those who had an exacerbation. The saEPI was associated with a high negative predictive value in both groups. CONCLUSIONS: An exacerbation in children treated with GBT with or without omalizumab was associated with a higher saEPI along with higher markers of allergic inflammation, treatment step, and a recent exacerbation. Those that exacerbated on omalizumab had similar features with the exception of some markers of allergic sensitization, indicating a need to develop better markers to predict poor response to omalizumab therapy and alternative treatment strategies for children with these risk factors. The saEPI was able to reliably predict those children unlikely to have an asthma exacerbation in both groups