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1.
Expert Rev Vaccines ; 23(1): 186-195, 2024.
Article in English | MEDLINE | ID: mdl-38164695

ABSTRACT

BACKGROUND: New York State (NYS) reported a polio case (June 2022) and outbreak of imported type 2 circulating vaccine-derived poliovirus (cVDPV2) (last positive wastewater detection in February 2023), for which uncertainty remains about potential ongoing undetected transmission. RESEARCH DESIGN AND METHODS: Extending a prior deterministic model, we apply an established stochastic modeling approach to characterize the confidence about no circulation (CNC) of cVDPV2 as a function of time since the last detected signal of transmission (i.e. poliovirus positive acute flaccid myelitis case or wastewater sample). RESULTS: With the surveillance coverage for the NYS population majority and its focus on outbreak counties, modeling suggests a high CNC (95%) within 3-10 months of the last positive surveillance signal, depending on surveillance sensitivity and population mixing patterns. Uncertainty about surveillance sensitivity implies longer durations required to achieve higher CNC. CONCLUSIONS: In populations that maintain high overall immunization coverage with inactivated poliovirus vaccine (IPV), rare polio cases may occur in un(der)-vaccinated individuals. Modeling demonstrates the unlikeliness of type 2 outbreaks reestablishing endemic transmission or resulting in large absolute numbers of paralytic cases. Achieving and maintaining high immunization coverage with IPV remains the most effective measure to prevent outbreaks and shorten the duration of imported poliovirus transmission.


Subject(s)
Poliomyelitis , Poliovirus , Humans , United States/epidemiology , Poliovirus Vaccine, Oral , Wastewater , Poliomyelitis/epidemiology , Poliomyelitis/prevention & control , Poliovirus Vaccine, Inactivated , Disease Outbreaks/prevention & control
2.
Appl Physiol Nutr Metab ; 49(1): 87-92, 2024 Jan 01.
Article in English | MEDLINE | ID: mdl-37639728

ABSTRACT

TAKE HOME MESSAGE: Musculoskeletal injuries and disordered eating are prevalent in varsity-level athletes but are not associated in our participants.


Subject(s)
Athletes , Feeding and Eating Disorders , Humans , Universities , Surveys and Questionnaires , Feeding and Eating Disorders/epidemiology
3.
J Infect Dis ; 229(4): 1097-1106, 2024 Apr 12.
Article in English | MEDLINE | ID: mdl-37596838

ABSTRACT

BACKGROUND: In July 2022, New York State (NYS) reported a case of paralytic polio in an unvaccinated young adult, and subsequent wastewater surveillance confirmed sustained local transmission of type 2 vaccine-derived poliovirus (VDPV2) in NYS with genetic linkage to the paralyzed patient. METHODS: We adapted an established poliovirus transmission and oral poliovirus vaccine evolution model to characterize dynamics of poliovirus transmission in NYS, including consideration of the immunization activities performed as part of the declared state of emergency. RESULTS: Despite sustained transmission of imported VDPV2 in NYS involving potentially thousands of individuals (depending on seasonality, population structure, and mixing assumptions) in 2022, the expected number of additional paralytic cases in years 2023 and beyond is small (less than 0.5). However, continued transmission and/or reintroduction of poliovirus into NYS and other populations remains a possible risk in communities that do not achieve and maintain high immunization coverage. CONCLUSIONS: In countries such as the United States that use only inactivated poliovirus vaccine, even with high average immunization coverage, imported polioviruses may circulate and pose a small but nonzero risk of causing paralysis in nonimmune individuals.


Subject(s)
Poliomyelitis , Poliovirus , Humans , Disease Outbreaks/prevention & control , New York/epidemiology , Poliomyelitis/epidemiology , Poliomyelitis/prevention & control , Poliovirus/genetics , Poliovirus Vaccine, Inactivated , Poliovirus Vaccine, Oral , Wastewater-Based Epidemiological Monitoring
4.
Ann Epidemiol ; 91: 74-81, 2024 Mar.
Article in English | MEDLINE | ID: mdl-37995986

ABSTRACT

PURPOSE: To determine the distribution of diagnosed SARS-CoV-2 infections by testing modality (at-home rapid antigen [home tests] versus laboratory-based tests in clinical settings [clinical tests]), assess factors associated with clinical testing, and estimate the true total number of diagnosed infections in New York State (NYS). METHODS: We conducted an online survey among NYS residents and analyzed data from 1012 adults and 246 children with diagnosed infection July 13-December 7, 2022. Weighted descriptive and logistic regression model analyses were conducted. Weighted percentages and prevalence ratios by testing modality were generated. The percent of infections diagnosed by clinical tests via survey data were synthesized with daily lab-reported results to estimate the total number of diagnosed SARS-CoV-2 infections in NYS July 1-December 31, 2022. RESULTS: Over 70% of SARS-CoV-2 infections in NYS during the study period were diagnosed exclusively with home tests. Diagnosis with a clinical test was associated with age, race/ethnicity, and region among adults, and sex, age, and education among children. We estimate 4.1 million NYS residents had diagnosed SARS-CoV-2 infection July 1-December 31, 2022, compared to 1.1 million infections reported over the same period. CONCLUSIONS: Most SARS-CoV-2 infections in NYS were diagnosed exclusively with home tests. Surveillance metrics using laboratory-based reporting data underestimate diagnosed infections.


Subject(s)
COVID-19 , SARS-CoV-2 , Adult , Child , Humans , COVID-19/diagnosis , COVID-19/epidemiology , COVID-19 Testing , New York/epidemiology , Clinical Laboratory Techniques/methods
6.
J Neurosci Methods ; 178(2): 334-9, 2009 Apr 15.
Article in English | MEDLINE | ID: mdl-19146879

ABSTRACT

Recent neuroscience methods have provided the basis upon which to develop effective gait training methods for recovery of the coordinated components of gait after neural injury. We determined that there was not an existing observational measure that was, at once, adequately comprehensive, scored in an objectively-based manner, and capable of assessing incremental improvements in the coordinated components of gait. Therefore, the purpose of this work was to use content valid procedures in order to develop a relatively inexpensive, more comprehensive measure, scored with an objectively-based system, capable of incrementally scoring improvements in given items, and that was both reliable and capable of discriminating treatment response for those who had a stroke. Eight neurorehabilitation specialists developed criteria for the gait measure, item content, and scoring method. In subjects following stroke (>12 months), the new measure was tested for intra- and inter-rater reliability using the Intraclass Correlation Coefficient; capability to detect treatment response using Wilcoxon Signed Ranks Test; and discrimination between treatment groups, using the Plum Ordinal Regression. The Gait Assessment and Intervention Tool (G.A.I.T.) is a 31-item measure of the coordinated movement components of gait and associated gait deficits. It exhibited the following advantages: comprehensive, objective-based scoring method, incremental measurement of improvement within given items. The G.A.I.T. had good intra- and inter-rater reliability (ICC=.98, p=.0001, 95% CI=.95, .99; ICC=.83, p=.007, 95% CI=.32, .96, respectively. The inexperienced clinician who had training, had an inter-rater reliability with an experienced rater of ICC=.99 (p=.0001, CI=.97, .999). The G.A.I.T. detected improvement in response to gait training for two types of interventions: comprehensive gait training (z=-2.93, p=.003); and comprehensive gait training plus functional electrical stimulation (FES; z=-3.3, p=.001). The G.A.I.T. was capable of discriminating between two gait training interventions, showing an additive advantage of FES to otherwise comparable comprehensive gait training (parameter estimate=1.72, p=.021; CI, .25, 3.1).


Subject(s)
Gait , Movement Disorders/diagnosis , Biomechanical Phenomena , Electric Stimulation Therapy , Humans , Leg , Movement Disorders/etiology , Movement Disorders/therapy , Reproducibility of Results , Severity of Illness Index , Stroke/complications , Stroke/therapy
7.
Mil Med ; 166(8): 714-20, 2001 Aug.
Article in English | MEDLINE | ID: mdl-11515324

ABSTRACT

The present review examines the impact of basic recruit training on health and lifestyle. Many of those recruited begin training with a less than optimal lifestyle with respect to fitness, smoking habits, alcohol consumption, drug abuse, and exposure to sexually transmitted diseases. Thus, there is scope to enhance training programs that address fitness and lifestyle, minimizing potential losses in health and efficiency from upper respiratory infections, musculoskeletal injuries, cardiac catastrophes, mental disturbances, and adverse responses to extreme environments.


Subject(s)
Health Behavior , Military Personnel , Acute Disease , Canada , Death, Sudden/etiology , Female , Humans , Immunity , Infections/immunology , Male , Mental Health , Musculoskeletal System/injuries , Physical Exertion , Physical Fitness , Risk , Smoking/adverse effects , Smoking/epidemiology , Substance-Related Disorders/epidemiology , Time Factors
8.
Am J Physiol Regul Integr Comp Physiol ; 281(1): R66-75, 2001 Jul.
Article in English | MEDLINE | ID: mdl-11404280

ABSTRACT

This study tested the hypothesis that exercise elicits monocytic cytokine expression and that prolonged cold exposure modulates such responses. Nine men (age, 24.6 +/- 3.8 y; VO(2 peak), 56.8 +/- 5.6 ml. kg(-1). min(-1)) completed 7 days of exhausting exercise (aerobic, anaerobic, resistive) and underwent three cold, wet exposures (CW). CW trials comprised

Subject(s)
Cold Temperature , Cytokines/blood , Monocytes/metabolism , Physical Exertion/physiology , Adult , Epinephrine/blood , Flow Cytometry , Humans , Hydrocortisone/blood , Interleukin-1/blood , Interleukin-6/blood , Leukocyte Count , Lipopolysaccharide Receptors/analysis , Male , Monocytes/chemistry , Monocytes/immunology , Norepinephrine/blood , Regression Analysis , Stress, Physiological/immunology , Stress, Physiological/metabolism , Tumor Necrosis Factor-alpha/metabolism
9.
Mil Med ; 165(11): 878-83, 2000 Nov.
Article in English | MEDLINE | ID: mdl-11143439

ABSTRACT

The effect of an 18.5-week infantry training program on health status was studied in 23 male military personnel (aged 22.0 +/- 0.5 years, mean +/- SE). Aerobic power, body composition, and immune function (including natural killer cell activity, mitogen-stimulated lymphocyte proliferation, in vivo cell-mediated immunity, and secretory immunoglobulin A levels) were measured in subjects at the beginning and end of the course. Subjects self-reported their symptoms of sickness in health logs using a precoded checklist. Data from this study indicate that subjects became leaner and maintained, but did not increase, their aerobic fitness by the end of the course. Cell function was enhanced significantly; however, in vivo cell-mediated immunity remained the same, and levels of secretory immunoglobulin A were lower by the end of the course. The incidence of infection remained stable throughout the course. These results indicate that the current pattern of infantry training does not have an adverse effect on the health status of recruits.


Subject(s)
Immunity , Infections/epidemiology , Military Personnel , Physical Fitness , Adult , Canada/epidemiology , Health Status , Humans , Hydrocortisone/blood , Immunity, Cellular , Immunoglobulin A, Secretory/blood , Incidence , Killer Cells, Natural/immunology , Lymphocyte Subsets , Male
10.
Fresenius J Anal Chem ; 368(1): 79-87, 2000 Sep.
Article in English | MEDLINE | ID: mdl-11220836

ABSTRACT

Laser ablation inductively coupled plasma mass spectrometry using a quadrupole-based mass spectrometer (LA-ICP-QMS) was applied for the analysis of powdered zeolites (microporous aluminosilicates) used for clean-up procedures. For the quantitative determination of trace element concentrations three geological reference materials, granite NIM-G, lujavrite NIM-L and syenite NIM-S, from the National Institute for Metallurgy (South Africa) with a matrix composition corresponding to the zeolites were employed. Both the zeolites and reference materials were fused with a lithium borate mixture to increase the homogeneity and to eliminate mineralogical effects. In order to compare two different approaches for the quantification of analytical results in LA-ICP-MS relative sensitivity coefficients (RSCs) of chemical elements and calibration curves were measured using the geostandards. The experimentally obtained RSCs are in the range of 0.2-6 for all elements of interest. Calibration curves for trace elements were measured without and with Li or Ti as internal standard element. With a few exceptions the regression coefficients of the calibration curves are better than 0.993 with internal standardization. NIM-G granite reference material was employed to evaluate the accuracy of the technique. Therefore, the measured concentrations were corrected with RSCs which were determined using lujavrite reference material NIM-L. This quantification method provided analytical results with deviations of 1-11% from the recommended and proposed values in granite reference material NIM-G, except for Co, Cs, La and Tb. The relative standard deviation (RSD) of the determination of the trace element concentration (n = 5) is about 1% to 6% using Ti as internal standard element. Detection limits of LA-ICP-QMS in the lower microg/g range (from 0.03 microg/g for Lu, Ta and Th to 7.3 microg/g for Cu, with the exception of La) have been achieved for all elements of interest. Under the laser ablation conditions employed (lambda: 266 nm, repetition frequency: 10 Hz, pulse energy: 10 mJ, laser power density: 6 x 10(9) W/cm2) fractionation effects of the determined elements relative to the internal standard element Ti were not observed.

11.
Am J Psychother ; 53(3): 344-60, 1999.
Article in English | MEDLINE | ID: mdl-10586298

ABSTRACT

The author contends that a psychoanalytically informed approach to the patient with dissociative identity disorder (DID) can be very useful. However, there are difficulties in conceptualizing this condition without extending existing theory or applying in new ways what is already known. It is also difficult to put DID in a proper context relative to all the other disorders known to occur in the human mind. Depending on one's clinical experience, level of skepticism, and appreciation of history, DID may be seen as either: a) the psychological "missing link" that realizes Freud's goal of uniting the psychology of dreams with psychopathology, or b) a fraudulent condition that is wittingly or unwittingly manufactured in the therapist's office or c) a population of disturbed and disturbing patients, once the subject of great scientific interest, which, exiled like a "Lost Tribe," is now back in the fold of legitimacy. The author has had extensive clinical experience with psychic trauma, and bases his own views of DID on three assumptions: 1. that dissociation may be seen as a complex defense; 2. that DID may be thought of as a "lower level dissociative character"; and 3. that there is a unique psychic structure, the "dissociative self" whose function is to create "alter personalities" out of disowned affects, memories, fantasies, and drives. This "dissociative self" must be dissolved in order for integration of "alter personalities" to occur. A clinical vignette is offered to illustrate how he addresses some of the challenges of developing a therapeutic alliance at this end of the dissociative-character-pathology continuum, and how he grapples with the difficulty of integrating clinical phenomena, such as the appearance of "alters," with the psychoanalytic model of the mind.


Subject(s)
Dissociative Identity Disorder/psychology , Dissociative Identity Disorder/therapy , Adult , Female , Humans , Psychoanalytic Therapy/methods
13.
J Appl Physiol (1985) ; 87(3): 1178-85, 1999 Sep.
Article in English | MEDLINE | ID: mdl-10484593

ABSTRACT

The contribution of hyperthermia to the differential leukocytosis of exercise remains obscure. This study examined changes in circulating sympathoadrenal hormone concentrations and patterns of leukocyte and lymphocyte subset (CD3(+), CD4(+), CD8(+), CD19(+), CD3(-)16(+)/56(+)) redistribution during exercise, with and without a significant rise of rectal temperature (T(re)). Ten healthy men [age 26.9 +/- 5.7 (SD) yr, body mass 76.0 +/- 10.9 kg, body fat 13.9 +/- 4.6%, peak O(2) consumption: 48.0 +/- 12.4 ml x kg(-1) x min(-1)] exercised for 40 min (65% peak O(2) consumption) during water immersion at 39 or 18 degrees C. T(re) increased from 37.2 to 39.3 degrees C (P < 0.0001) after 40 min of exercise in 39 degrees C water but was held constant to an increment of 0.5 degrees C during exercise in 18 degrees C water. Application of this thermal clamp reduced exercise-associated increments of plasma epinephrine (Epi) and norepinephrine (NE) by >50% (P < 0.05) and abolished the postexercise increase in cortisol. Thermal clamping also reduced the exercise-induced leukocytosis and lymphocytosis. Multiple regression demonstrated that T(re) had no direct association with lymphocyte subset mobilization but was significantly (P < 0.0001) correlated with hormone levels. Epi was an important determinant of total leukocytes, lymphocytes, and CD3(+), CD4(+), CD8(+), and CD3(-)CD16(+)/56(+) subset redistribution. The relationship between NE and lymphocyte subsets was weaker than that with Epi, with the exception of CD3(-)CD16(+)/56(+) counts, which were positively (P < 0.0001) related to NE. Cortisol was negatively associated with leukocytes, CD14(+) monocytes, and CD19(+) B- and CD4(+) T-cell subsets but was positively related to granulocytes. We conclude that hyperthermia mediates exercise-induced immune cell redistribution to the extent that it causes sympathoadrenal activation, with alterations in circulating Epi, NE, and cortisol.


Subject(s)
Adrenal Glands/physiology , Body Temperature/physiology , Exercise/physiology , Sympathetic Nervous System/physiology , T-Lymphocyte Subsets/physiology , Adult , Blood Volume/physiology , Catecholamines/blood , Exercise Test , Hematocrit , Hemoglobins/metabolism , Humans , Hydrocortisone/blood , Immersion , Immunophenotyping , Male
14.
Eur J Appl Physiol Occup Physiol ; 80(5): 452-60, 1999 Oct.
Article in English | MEDLINE | ID: mdl-10502079

ABSTRACT

It was hypothesized that muscle injury would be greater with eccentric than with all-out or prolonged exercise, and that immune changes might provide an indication that supplements the information provided by traditional markers such as creatine kinase (CK) or delayed-onset muscle soreness. Eight healthy males [mean (SE): age = 24.9 (2.3) years, maximum oxygen consumption (VO2(max)) = 43.0 (3.1) ml x kg(-1) x min(-1)] were each assigned to four experimental conditions, one at a time, using a randomized-block design: 5 min of cycle ergometer exercise at 90% VO2(max) (AO), a standard circuit-training routine (CT), 2 h cycle ergometer exercise at 60% VO2(max) (Long), or remained seated for 5 h. Blood samples were analyzed for CK, natural killer (NK) cell counts (CD3(-)/CD16(+)56(+)), cytolytic activity and plasma levels of the cytokines interleukin (IL)-6, IL-10, and tissue necrosis factor alpha (TNF-alpha). CK levels were only elevated significantly 72 h following CT. NK cell counts increased significantly during all three types of exercise, but returned to pre-exercise baseline values within 3 h of recovery. Cytolytic activity per NK cell was not significantly modified by any type of exercise. Prolonged exercise induced significant increases in plasma IL-6 and TNF-alpha. We conclude that the lack of correlation between traditional markers of muscle injury (plasma CK concentrations and muscle soreness rankings) and immune markers of the inflammatory response suggests that, for the types and intensities of exercise examined in this study, the exercise-induced inflammatory response is modified by humoral and cardiovascular correlates of exercise.


Subject(s)
Exercise/physiology , Inflammation/immunology , Muscle, Skeletal/injuries , Adult , Blood Pressure , Body Temperature , Creatine Kinase/blood , Cytokines/blood , Heart Rate , Humans , Inflammation/etiology , Inflammation/physiopathology , Killer Cells, Natural , Lymphocyte Count , Male , Muscle, Skeletal/physiopathology , Oxygen Consumption , Pain
15.
J Appl Physiol (1985) ; 87(2): 699-710, 1999 Aug.
Article in English | MEDLINE | ID: mdl-10444630

ABSTRACT

This study examined the immunological responses to cold exposure together with the effects of pretreatment with either passive heating or exercise (with and without a thermal clamp). On four separate occasions, seven healthy men [mean age 24.0 +/- 1.9 (SE) yr, peak oxygen consumption = 45.7 +/- 2.0 ml. kg(-1). min(-1)] sat for 2 h in a climatic chamber maintained at 5 degrees C. Before exposure, subjects participated in one of four pretreatment conditions. For the thermoneutral control condition, subjects remained seated for 1 h in a water bath at 35 degrees C. In another pretreatment, subjects were passively heated in a warm (38 degrees C) water bath for 1 h. In two other pretreatments, subjects exercised for 1 h at 55% peak oxygen consumption (once immersed in 18 degrees C water and once in 35 degrees C water). Core temperature rose by 1 degrees C during passive heating and during exercise in 35 degrees C water and remained stable during exercise in 18 degrees C water (thermal clamping). Subsequent cold exposure induced a leukocytosis and granulocytosis, an increase in natural killer cell count and activity, and a rise in circulating levels of interleukin-6. Pretreatment with exercise in 18 degrees C water augmented the leukocyte, granulocyte, and monocyte response. These results indicate that acute cold exposure has immunostimulating effects and that, with thermal clamping, pretreatment with physical exercise can enhance this response. Increases in levels of circulating norepinephrine may account for the changes observed during cold exposure and their modification by changes in initial status.


Subject(s)
Exercise/physiology , Hot Temperature , Hypothermia/physiopathology , Adult , Antigens, CD/immunology , Cold Temperature , Granulocytes/immunology , Hormones/blood , Humans , Hypothermia/immunology , Immersion , Immunophenotyping , Interleukin-6/blood , Killer Cells, Natural/immunology , Leukocyte Count , Lymphocyte Subsets/immunology , Male , Oxygen Consumption , Time Factors
16.
Undersea Hyperb Med ; 26(1): 27-39, 1999.
Article in English | MEDLINE | ID: mdl-10353182

ABSTRACT

The purpose of this review is to examine the influence of exposure to hyperbaric oxygen (HBO2) deep diving, and decompression on various facets of the immune response. Potential changes during exposure include a decrease in the CD4+:CD8+ ratio, a decreased proliferation of lymphocytes, and an activation of neutrophils with migration to regions of high oxygen pressure. There may also be an activation of the complement cascade during decompression. Clinical indicators of overall immune suppression include a decreased response to antigens, a weakening of autoimmune responses, and a slower rejection of allografts. In professional divers, immune changes are at least partially offset by acclimatization, and seem to have little clinical significance. However, patients receiving HBO2 are a more vulnerable group; in their case, exposure may impair immune surveillance, and a careful monitoring of immune function may be important to the success of treatment.


Subject(s)
Antibody Formation/physiology , Decompression , Diving/physiology , Hyperbaric Oxygenation , Immunity, Cellular/physiology , Animals , CD4-CD8 Ratio , Complement System Proteins/metabolism , Hormones/metabolism , Humans , Immunoglobulins/metabolism , Immunosuppression Therapy , Leukocyte Count , Lymphocyte Activation , Reactive Oxygen Species/metabolism
17.
Med Sci Sports Exerc ; 31(6): 792-9, 1999 Jun.
Article in English | MEDLINE | ID: mdl-10378905

ABSTRACT

PURPOSE: This study examined the effects of advancing gestational age and maternal aerobic conditioning (stationary cycling) on fetal heart rate (FHR) responses to strenuous non-steady-state maternal exercise. METHODS: Subjects chose to participate in either an exercise group (EG) or control group (CG). Fourteen healthy, previously sedentary pregnant women participated in the exercise group, and six pregnant controls remained sedentary. Stationary cycling (heart rate target: 145 beats x min(-1)) was performed 3 d x wk(-1) by the exercised group. Exercise duration was increased from 14 to 25 min x session(-1) during the second trimester and was maintained at 25 min x session(-1) throughout the third trimester. FHR was monitored before, during, and after a progressive submaximal cycle ergometer test (peak heart rate = 170 beats x min(-1)) performed at approximately 27 and 37 wk gestation. RESULTS: Mean FHR increased significantly (P < 0.05) during exercise, followed by a modest suppression and then a delayed rise during the recovery period at both observation times. Fetal bradycardia was not observed in any of the exercise tests. Effects of advancing gestational age included a lower FHR baseline both at rest and in response to maternal exercise and a lower incidence of exercise-induced tachycardia. Maternal physical conditioning did not significantly alter FHR response to maternal exercise. CONCLUSION: Our results support the hypothesis that FHR responses to strenuous exercise are altered by advancing gestational age and a brief progressive exercise test terminated at a maternal heart rate of 170 beats x min(-1) does not induce fetal distress during a healthy pregnancy.


Subject(s)
Exercise/physiology , Heart Rate, Fetal/physiology , Pregnancy/physiology , Adult , Female , Fetal Distress/physiopathology , Gestational Age , Humans , Physical Endurance/physiology
18.
Sports Med ; 26(2): 85-99, 1998 Aug.
Article in English | MEDLINE | ID: mdl-9777682

ABSTRACT

Minimal information is available on the autonomic response to exercise under adverse environmental conditions. Traditionally, pharmacological blockade has been used to study autonomic responsiveness but, owing to its invasive nature, such studies have been limited in their scope. Recent advances in electrocardiographic tape recording, telemetry and associated computing systems have provided investigators with noninvasive methods for assessing the autonomic response to various physiological stressors. This article describes methods for the analysis of heart rate variability (HRV) and discusses the reports of those who have used HRV analysis to evaluate autonomic regulation during exercise, heat exposure and the combination of these 2 stressors. Spectral analysis of HRV reduces variations in the R-R interval into component sine waves of differing amplitude and frequency. Amplitude (variance) is displayed as a function of frequency, and power (cumulative variance) is calculated for specified frequency ranges (< 0.03 Hz, 0.03 to 0.15 Hz and 0.15 to 0.5 Hz). Parasympathetic nervous system activity can be inferred from the several indices of high frequency power; however, the estimation of sympathetic nervous system activity from low frequency power is more problematic. Data on HRV have shown that sympathovagal regulation during exercise is dependent on the intensity of the activity and the environmental conditions. At the onset of exercise, heart rate is increased by a reduction in vagal tone and a temporary increase in sympathetic tone. A continuation of physical activity is associated with a continued withdrawal of vagal activity and an attenuation of sympathetic nervous system tone. However, with the additional stimulus of a heated environment, sympathetic activity remains increased throughout exercise.


Subject(s)
Autonomic Nervous System/physiology , Blood Circulation/physiology , Exercise/physiology , Heart Rate/physiology , Hot Temperature , Adult , Female , Humans , Male
19.
Naunyn Schmiedebergs Arch Pharmacol ; 358(2): 245-52, 1998 Aug.
Article in English | MEDLINE | ID: mdl-9750011

ABSTRACT

The role of potassium intake in the response of kidney function and plasma renin activity (PRA) to systemic application of U37883A (4-morpholinecarboximidine-N-1-adamantyl-N'-cyclohexyl-hydro chloride), a putative blocker of ATP-sensitive potassium channels (K(ATP)), and P1075 (N-cyano-N'-(1,1-dimethylpropyl)-N"-pyridylguanidine), an opener of K(ATP) channels, was studied in the anesthetized rat. It was found that under normal potassium diet (0.7% K), U37883A (15 mg/kg, i.v.) increased urinary flow rate (UV) and sodium excretion (UNaV), decreased urinary potassium excretion (UKV), and significantly diminished heart rate (HR) without affecting mean arterial blood pressure (MAP) or glomerular filtration rate (GFR). P1075 (10 microg/kg, i.v.) lowered UV, UNaV and UKV, at least in part due to the fall in MAP and GFR. PRA was diminished by U37883A and increased by P1075. Variation in potassium diet (0.04 or 2% K) left the response in MAP, HR or GFR to both potassium channel modulators essentially unchanged. The reduction in renal excretion rates to P1075 also appeared unaffected, further supporting a predominant role of the change in MAP and GFR in this response. Variation in potassium diet, however, elicited the following alterations: (1) under both low and high potassium diet U37883A did no longer cause a significant natriuresis; (2) U37883A elicited a significant kaliuresis under high potassium diet, whereas potassium excretion remained essentially unchanged on very low levels under low potassium diet; (3) the increase in PRA to P1075 was blunted under low potassium diet. Additional experiments provided evidence that P1075 releases renin from freshly isolated juxtaglomerular cells of rats on normal but not on low potassium diet. In summary, systemic potassium channel modulation employing U37883A or P1075, respectively, exerts distinct effects on blood pressure and heart rate independent of potassium diet. In contrast, potassium diet appears to be a determinant for the concomitant responses in plasma renin activity and renal sodium and potassium excretion.


Subject(s)
Kidney/drug effects , Potassium, Dietary/administration & dosage , Adamantane/analogs & derivatives , Adamantane/pharmacology , Animals , Blood Pressure/drug effects , Body Fluids/drug effects , Diuretics/pharmacology , Dose-Response Relationship, Drug , Glomerular Filtration Rate/drug effects , Guanidines/pharmacology , Heart Rate/drug effects , Juxtaglomerular Apparatus/cytology , Juxtaglomerular Apparatus/drug effects , Juxtaglomerular Apparatus/metabolism , Kidney/physiology , Male , Morpholines/pharmacology , Potassium/blood , Potassium/urine , Potassium Channels/drug effects , Pyridines/pharmacology , Rats , Rats, Sprague-Dawley , Renin/blood , Renin/drug effects , Renin/metabolism , Sodium/blood , Sodium/urine , Vasodilator Agents/pharmacology
20.
Int J Sports Med ; 19(2): 130-43, 1998 Feb.
Article in English | MEDLINE | ID: mdl-9562223

ABSTRACT

This review focuses on the response of "stress" hormones to heat, exercise (single or repeated bouts), and combinations of these stimuli, with particular reference to their impact upon immune function. Very hot conditions induce a typical stress response, with secretion of catecholamines and cortisol. The catecholamines induce a demargination of leukocytes, and cortisol subsequently causes cells to migrate to lymphoid tissue. Sustained exercise, even in a thermally comfortable environment, induces a larger hormonal response than moderate thermal stress. With moderate exercise, increases in leukocyte numbers are related mainly to plasma norepinephrine concentrations, but with more intense exercise epinephrine concentrations assume a major importance. As exercise continues, plasma cortisol levels also rise, inducing an influx of neutrophils from bone marrow and an efflux of other leukocyte subsets. A combination of exercise and heat stress augments both hormonal and leukocyte responses. But these changes seem to be reversed if temperatures are clamped by exercising in cold water. If a second bout of exercise is performed with an inter-test interval of 30-45 min, neither hormone concentrations nor immune responses show any great cumulative effect under temperate conditions. However, in a hot environment the second exercise bout induces a larger and more persistent neutrophilia. Training influences these various responses mainly by decreasing the stress imposed when exercising at a given absolute work-rate.


Subject(s)
Epinephrine/metabolism , Exercise/physiology , Heat Stress Disorders/immunology , Human Growth Hormone/metabolism , Hydrocortisone/metabolism , Norepinephrine/metabolism , Physical Exertion/physiology , Stress, Physiological/immunology , Body Temperature Regulation/immunology , Body Temperature Regulation/physiology , Bone Marrow Cells/immunology , Bone Marrow Cells/physiology , Cell Movement , Epinephrine/blood , Epinephrine/immunology , Heat Stress Disorders/physiopathology , Hot Temperature/adverse effects , Human Growth Hormone/immunology , Humans , Hydrocortisone/blood , Hydrocortisone/immunology , Leukocyte Count , Leukocytes/immunology , Leukocytes/physiology , Neutrophils/immunology , Neutrophils/physiology , Norepinephrine/blood , Norepinephrine/immunology , Stress, Physiological/physiopathology
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