A Personal Biography of a Physiological Misnomer: The Anaerobic Threshold

In 1973 Wasserman, Whipp, Koyal, and Beaver published a groundbreaking study titled "Anaerobic threshold and respiratory gas analysis during exercise". At that time, respiratory gas analysis and laboratory computers had evolved such that more advanced respiratory exercise physiology studies were possible. The initial publications from this group on the onset of anaerobic metabolism in cardiac patients, the first breath-by-breath VO₂ system, the first description of the anaerobic threshold, and then later new methods to detect the anaerobic threshold have been and continue to be highly cited. In fact, their 1973 anaerobic threshold paper is the sixth and their 1986 paper is the second most cited paper ever published in the Journal of Applied Physiology. The anaerobic threshold concept has also generated>5500 publications with the rates increasing over time. The publication of two papers that help to refute the "anaerobic" explanation for this phenomenon had no effect on the rates of citations of the original anaerobic threshold papers or the number of anaerobic threshold papers published since. Thus, despite now substantial evidence refuting the proposed anaerobic mechanisms underlying this phenomenon, these papers continue to be highly influential in the discipline of exercise physiology and, perhaps even more explicitly, clinical exercise physiology.

Effects of Exercise Training on the Paracrine Function of Circulating Angiogenic Cells

Exercise training has various benefits on cardiovascular health, and circulating angiogenic cells have been proposed as executing these changes. Work from the late 1990s supported an important role of these circulating post-natal cells in contributing to the maintenance and repair of the endothelium and vasculature. It was later found that circulating angiogenic cells were a heterogenous population of cells and primarily functioned in a paracrine manner by adhering to damaged endothelium and releasing growth factors. Many studies have discovered novel circulating angiogenic cell secreted proteins, microRNA and extracellular vesicles that mediate their angiogenic potential, and some studies have shown that both acute and chronic aerobic exercise training have distinct benefits. This review highlights work establishing an essential role of secreted factors from circulating angiogenic cells and summarizes studies regarding the effects of exercise training on these factors. Finally, we highlight the various gaps in the literature in hopes of guiding future work.

Effect of exercise on metabolic syndrome in black women by family history and predicted risk of breast cancer: The FIERCE Study

BACKGROUND

This study examined the effects of supervised and home-based exercise interventions on changes in metabolic syndrome (MetS) according to breast cancer risk (high vs low) in black women enrolled in the Focused Intervention on Exercise to Reduce Cancer (FIERCE) trial.

METHODS

Postmenopausal, obese, metabolically unhealthy black women, 45 to 65 years old, were randomized to supervised aerobic exercise (73 women), home-based walking-based exercise (69 women), or a control arm (71 women). Participants in the exercise arms underwent a 6-month intervention with study assessments conducted at the baseline and 6 months. The primary outcome measure was MetS (fasting glucose, waist circumference, blood pressure, serum triglycerides, and high-density lipoprotein [HDL]). The intervention effects on MetS, stratified by breast cancer risk as measured by the family history of breast cancer and model-based projected breast cancer risk, were examined with intent-to-treat analyses using generalized estimating equation models.

RESULTS

Among women with a family history of breast cancer, the exercise arms had lower mean MetS z scores, which suggested an improvement in the metabolic profile, than controls at 6 months (controls, + 0.55; home-based arm, -0.97, P < .01; supervised arm, -0.89, P < .01). Stratified analyses by projected breast cancer risk suggested similar but statistically nonsignificant findings, with those at high risk having more favorable changes in the MetS z score in the exercise arms versus the control arm. These changes were primarily attributable to changes in blood pressure, triglycerides, and HDL.

CONCLUSIONS

Short-term aerobic activity regimens may improve the metabolic profile and thereby reduce breast cancer risk in obese, metabolically unhealthy black women at high risk for cancer. © 2018 American Cancer Society.

Temporal trends of PBDD/Fs, PCDD/Fs, PBDEs and PCBs in ringed seals from the Baltic Sea (Pusa hispida botnica) between 1974 and 2015

Temporal trends in exposure to persistent organic pollutants (POPs) were assessed in 22 pooled samples gathered from 69 individuals of Baltic ringed seal (Pusa hispida botnica) from 1974 to 2015. Samples were analysed for polybrominated dibenzo-p-dioxins and furans (PBDD/Fs), polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs). No previous study has reported on the occurrence of PBDD/Fs in marine mammals in the Baltic Sea. Concentrations of pollutants in Baltic ringed seal, a marine mammal and top predator, can be used as an indicator of pollutants concentrations in the Baltic region. Visual inspection of data did not show any temporal trends for PBDD/Fs, while the PCDD/Fs and PCBs showed decreasing concentrations between 1974 and 2015. PBDEs increased until the end of the 1990s and then decreased until the end of the period. ∑PBDD/Fs ranged from 0.5-52.3pg/g lipid weight (l.w.) (0.08-4.8pgTEQ/g l.w.), with 1,2,3,4,6,7,8-HpBDF contributing on average 61% to ∑PBDD/Fs. ∑PCDD/Fs ranged from 103 to 1480pg/g l.w. (39-784pgTEQ/g l.w.), with 1,2,3,6,7,8-HxCDD, 1,2,3,7,8-PeCDD and 2,3,4,7,8-PeCDF showing the highest average concentrations. PBDD/F toxic equivalents (TEQ) contributed on average 1.1% to the total (PBDD/F+PCDD/F) TEQ. The ∑PBDEs concentration range was 18.7-503ng/g l.w., with BDE #47 the predominant congener. The concentration range for ∑PCBs was 2.8-40.1μg/g l.w., with #138 and #153 the most abundant congeners. Visual inspection of the data showed decreasing concentrations for all compound groups except PBDD/Fs. A slight increase in the PBDD/Fs concentrations was observed from 2004 onwards. This observation needs to be investigated further.

Occurrence of polybrominated dibenzo-p-dioxins, dibenzofurans (PBDD/Fs) and polybrominated diphenyl ethers (PBDEs) in pilot whales (Globicephala melas) caught around the Faroe Islands

Blubber from Faroese pilot whales (Globicephala melas) was analysed for brominated dioxins PBDD/Fs, with a subset also analysed for chlorinated dioxins, PCDD/Fs. The studied individuals were restricted to juvenile male whales sampled in the Faroe Islands during the period 1997-2013. Among the PBDD/Fs, the furans were predominant, although the relative abundance of various congeners differed between samples. Furans accounted for, on average, 79% of the ∑PBDD/Fs in the samples, with 1,2,3,4,6,7,8-HpBDF the most abundant congener, found in half of the analysed pilot whales. The concentration range for ∑PBDD/Fs among the samples was 0.080-71 pg/g l.w. (lipid weight), and the sum of toxic equivalents ranged from 0.0039 to 4.7 pg TEQ/g l.w. No relationship was found between PBDD/Fs and PCDD/Fs. In addition, 20 pilot whale samples from the period 2010-2013 were analysed for PBDEs. Several PBDE congeners were found in all of the sampled pilot whales, and at noticeably higher levels than PBDD/Fs and PCDD/Fs. The ∑PBDEs ranged from 140 to 1900 ng/g l.w., with BDE #47 the most abundant congener detected in the samples. Results from the present study were then compared with data from previous studies on pilot wales to investigate temporal trends between 1986 and 2013. The comparison indicated that PBDE concentrations in juvenile males have decreased from 1996 to the latest observations in 2013. No relationship between the concentration levels of PBDD/Fs and PBDEs in the sampled pilot whales could be identified, which indicates possible differences in the metabolism of, or exposure to, PBDEs and PBDD/Fs.

Abstract 4219: An exergaming intervention to reduce breast cancer risk in Black women

Obesity and low physical activity rates contribute to high rates of postmenopausal breast cancer in Black women. Use of new and exciting strategies to increase physical activity should be tested in health disparity populations at high risk of cancer. We tested the effect of a six-month exercise intervention using the active videogaming systems (exergaming) on anthropometric markers, body composition, and cardiovascular fitness (VO2max) in overweight and obese Black women. We conducted a six-month, two-arm randomized clinical trial comparing an exergaming intervention group to a control group in 100 cancer-free, overweight/obese, sedentary Black women who were 40-59 years of age. Participants were randomized to a supervised facility-based exergaming group (n=50) or a usual care control group (n=50). Participants in the exergaming group followed an exercise program using the Nintendo Wii Fit and/or the X-Box Kinect gaming systems under supervision of a clinical exercise physiologist. Control group participants were asked to maintain their normal daily activities. Endpoints were assessed at baseline, 3 months, and 6 months. Assessments included measurements of demographic variables, medical history, physical activity, VO2max, anthropometric variables (height, weight, waist and hip circumferences), and body composition. Distribution of baseline characteristics between exergaming and control groups was comparable except for education status and BMI. Data on 3 month and 6-month follow-up were available for 66 participants. Follow-up rates were similar for exergaming and control groups. Compared to control group participants whose waist circumference on average remained unchanged, exergaming group participants had lower waist circumference at 3-months and 6- months compared to baseline (mean change: -2.54 cm, P=0.05). Exergaming participants also had small changes in weight (-1.4 lbs) at 6 months compared to control group in whom average weight remained unchanged but this finding was not statistically significant. Fat mass and lean mass as measured by DXA did not show any changes at 3-months or 6-months in either the exergaming or the control group. This pilot study of a short-term exergaming in overweight/obese Black women was associated with small changes in waist circumference in the intervention group. Given the challenges associated with traditional physical activity interventions to reduce cancer risk, new and non-traditional interventions like exergaming should be tested in larger studies in health disparity populations.

Citation Format: Chiranjeev Dash, Jennifer Hicks, Vivian Watkins, Mary Mills, James Hagberg, Lucile L. Adams-Campbell. An exergaming intervention to reduce breast cancer risk in Black women [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4219. doi:10.1158/1538-7445.AM2017-4219

Uptake and bioaccumulation of PCDD/Fs in earthworms after in situ and in vitro exposure to soil from a contaminated sawmill site

Uptake of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) was studied in earthworms collected from a sawmill site in Sweden with severe PCDD/Fs contamination (the hot spot concentration was 690,000ng TEQ_WHO2005/kg d.w.) in order to investigate the transfer of PCDD/Fs from the site to the biota. PCDD/Fs concentrations in the collected earthworms were compared to PCDD/Fs concentrations in laboratory exposed earthworms (Eisenia fetida), which were exposed to contaminated soils from the sawmill site for 34days. All analyses were performed by high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS). PCDD/Fs concentrations in the earthworms ranged from 290 to 520,000pg/g (f.w.). The main congeners found in both soils and earthworms were OCDF, 1234678-HpCDF, OCDD and 1234678-HpCDD. The study showed that the PCDD/Fs in the soil were biovailable to the earthworms and the PCDD/Fs concentrations in the soils correlated with the concentrations in the earthworms. Earthworm samples from soil with lower concentration had higher bioaccumulation factors than samples from soils with high concentration of contamination. Thus, a less contaminated soil could yield higher concentrations in earthworms compared to a higher contaminated soil. Assuming that when assessing risks with PCDD/F contaminated soil, a combination of chemical analysis of soil PCDD/Fs concentrations and bioavailability should be employed for a more comprehensive risk assessment.

Validity and test-retest reliability of an at-work production loss instrument

BACKGROUND

Besides causing ill health, a poor work environment may contribute to production loss. Production loss assessment instruments emphasize health-related consequences but there is no instrument to measure reduced work performance related to the work environment.

AIMS

To examine convergent validity and test-retest reliability of health-related production loss (HRPL) and work environment-related production loss (WRPL) against a valid comparable instrument, the Health and Work Performance Questionnaire (HPQ).

METHODS

Cross-sectional study of employees, not on sick leave, who were asked to self-rate their work performance and production losses. Using the Pearson correlation and Bland and Altman's Test of Agreement, convergent validity was examined. Subgroup analyses were performed for employees recording problem-specific reduced work performance. Consistency of pairs of HRPL and WRPL for samples responding to both assessments was expressed using Intraclass Correlation Coefficient (ICC) and tests of repeatability.

RESULTS

A total of 88 employees participated and 44 responded to both assessments. Test of agreement between measurements estimates a mean difference of 0.34 for HRPL and -0.03 for WRPL compared with work performance. This indicates that the production loss questions are valid and moderately associated with work performance for the total sample and subgroups. ICC for paired HRPL assessments was 0.90 and 0.91 for WRPL, i.e. the test-retest reliability was good and suggests stability in the instrument.

CONCLUSIONS

HRPL and WRPL can be used to measure production loss due to health-related and work environment-related problems. These results may have implications for advancing methods of assessing production loss, which represents an important cost to employers.

Cardiorespiratory Fitness and Metabolic Syndrome in Postmenopausal African-American Women

We examined the association of cardiorespiratory fitness with metabolic syndrome in overweight/obese postmenopausal African-American women. Pooled baseline data on 170 African-American women from 2 exercise trials were examined. Metabolic syndrome was defined as at least 3 of the following: abdominal obesity, glucose intolerance, hypertension, low high-density lipoprotein cholesterol (HDL-C), and high triglycerides. Cardiorespiratory fitness (VO2peak) was determined using the Bruce treadmill protocol and categorized as: Very Low (VLCRF<18 mL·kg(-1) min(-1)), Low (LCRF=18.0-220-22-22.0 mL·kg(-1) min(-1)), and Moderate (MCRF>22.0 mL·kg(-1) min(-1)). Associations of metabolic syndrome with cardiorespiratory fitness were analyzed using one-way ANOVA and linear regression. VO2peak was significantly lower in the VLCRF compared to the MCRF group. Lower cardiorespiratory fitness was associated with higher prevalence of metabolic syndrome, abdominal obesity, hypertriglyceridemia, and low HDL among overweight/obese postmenopausal African-American women. In fully adjusted models, higher waist circumference and triglycerides were associated with lower VO2peak levels (P<0.01) and higher HDL-C was associated with higher VO2peak levels (P=0.03). Overweight/obese postmenopausal African-American women with very low cardiorespiratory fitness are more likely to have metabolic syndrome, higher body mass index, and unhealthier levels of certain metabolic syndrome components than women with moderate cardiorespiratory fitness.

Swedish translation and validation of a web-based questionnaire for registration of overuse problems

The main aim of this study was to translate the Oslo Sport Trauma Research Center (OSTRC) Overuse Injury Questionnaire into Swedish. The validity and applicability of the questionnaire for studying overuse injuries among Swedish handball, volleyball, tennis, and orienteering top athletes were also examined. The back-translation method was used for translation. An expert committee further developed it for use in a study of injuries in handball, orienteering, tennis, and volleyball. A 10-week pretest was then conducted on 43 athletes, average age 21 (18-31) from these sports, during which time the athletes completed the modified OSTRC questionnaire on a weekly basis. In the 10th week, four additional questions were added in order to examine the questionnaire's content validity. No major disagreement was found in the translation. The athletes perceived the web-based questionnaire to be smooth and easy to complete, accurately capturing overuse injuries. However, suggestions were made to add questions relating to the hip for orienteerers and to the hand/fingers for handball players. The average prevalence of overuse injuries for all athletes, in any anatomical area was 22% (95% confidence interval 20-25). Construct validity appeared to be high, and we therefore suggest that the questionnaire may be used when studying overuse injuries in different sports.

Assessment of PCDD/Fs levels in soil at a contaminated sawmill site in Sweden--a GIS and PCA approach to interpret the contamination pattern and distribution

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo-p-furans (PCDD/Fs) were analysed in soil from a Swedish sawmill site where chlorophenols (CPs) had been used more than 40 years ago. The most contaminated area at the site was the preservation subarea where the PCDD/F WHO2005-TEQ level was 3450 times higher than the current Swedish guideline value of 200 ng TEQ/kg soil for land for industrial use. It was also shown that a fire which destroyed the sawmill might have affected the congener distribution at the concerned areas. To get a broader picture of the contamination both GIS (spatial interpolation analysis) and multivariate data analysis (PCA) were applied to visualize and compare PCDD/F levels as well as congener distributions at different areas at the site. It is shown that GIS and PCA are powerful tools in decisions on future investigations, risk assessments and remediation of contaminated sites.

Relationships among changes in C-reactive protein and cardiovascular disease risk factors with lifestyle interventions

BACKGROUND AND AIMS

Inflammation plays a role in the development of cardiovascular disease (CVD). Elevated levels of the inflammatory marker, C-reactive protein (CRP), are cross-sectionally associated with traditional CVD risk factors and are being considered as an emerging CVD risk factor. In a secondary data analysis, we examined changes in CRP and several CVD risk factors after one-year diet and physical activity interventions to assess whether CRP changed concurrently with other risk factors, or was independent of the traditional risk factors.

METHODS AND RESULTS

Data were analyzed from 143 men and 133 women with dyslipidemia who were randomized to one-year interventions of low-fat diet only, physical activity only, diet plus physical activity, or control. Plasma high-sensitivity CRP, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides (TG), fasting and 2-hr blood glucose and insulin, blood pressure (BP), and waist circumference were obtained at baseline and follow-up. Multiple linear regression models were used to predict CRP change based on other risk factor changes, controlling for age, race, alcohol intake, and hormone replacement therapy. Treatment groups were combined for analysis. Baseline mean (SD) CRP levels were 1.3 ± 1.3 (men) and 1.9 ± 1.8 mg/L (women), with mean changes of -0.11 ± 1.3 and -0.17 ± 1.5 mg/L, respectively. Plasma CRP change was negatively associated with TG change in men (p = 0.003) and women (p = 0.05), positively associated with change in systolic BP in men (p = 0.01), but was not associated with changes in the other risk factors.

CONCLUSION

Dietary and/or physical activity induced changes in CRP may be largely independent of traditional CVD risk factors in persons with dyslipidemia.

The effects of aerobic training and age on plasma sICAM-1

Chronic low-grade systemic inflammation plays a role in the development of cardiovascular (CV) disease. Habitual endurance exercise training reduces the risk of CV disease in part through anti-inflammatory mechanisms. The purpose of this study was to investigate the effects of age, endurance training status, and their interaction on pro-inflammatory plasma cytokines involved in the pathogenesis of CV disease. Subjects were BMI-matched young (25±3 years; endurance trained: n=9, sedentary: n=11) and older (62±5 years; endurance-trained: n=12, sedentary: n=11) men. Plasma cytokine concentrations were determined by multiplex cytometric bead assay. Soluble intercellular adhesion molecule-1 (sICAM-1) levels were 40% higher in sedentary older men compared to young sedentary subjects (P=0.048), but they were not different between the young and older trained men. Furthermore, sICAM-1 levels were negatively correlated with maximal oxygen uptake (V˙O2max; r= - 0.38, P=0.01) across all subjects. There were no significant differences among the groups in plasma concentrations of monocyte chemoattractant protein-1 (MCP-1), soluble tumor necrosis-α receptor (sTNFR), soluble CD40 ligand (sCD40L), or resistin. We conclude that habitual endurance training is associated with an attenuated age-related increase in plasma sICAM-1.

The impact of bystanding to workplace bullying on symptoms of depression among women and men in industry in Sweden: an empirical and theoretical longitudinal study

Background

Prospective studies on bystanding to workplace bullying and the health outcomes are scarce.

Aim

To investigate the work environmental risk factors of depressive symptoms among bystanders to bullying in both women and men in four large industrial organizations in Sweden.

Method

The number of respondents at four large industrial enterprises with more than one year at the workplace at T1: n = 2,563 (Women: n = 342; Men: n = 2,227). Bystanders to bullying at T1: n = 305 (Women: n = 30; Men: n = 275). The total number of those with symptoms of depression at T2: Women: n = 30; Men: n = 161. Two thousand one hundred and seventy-seven employees answered the questionnaire on T1 and T2 with an 18-month interval. “To have depressive symptoms” was defined as not having depressive symptoms at T1 but having depressive symptoms at T2.

Results

The number of men who were bystanders to bullying was larger compared to women. However, the proportion of women who were bystanders to bullying and developed depressive symptoms 18 months later was higher in comparison with men (33.3 and 16.4 %, respectively). Further, “Being a bystander to bullying” 1.69 (1.13–2.53), “Rumors of changes in the workplace” 1.53 (1.10–2.14), “Reduced role clarity” 2.30 (1.21–4.32), “Lack of appreciation of being in the group” 1.76 (1.22–2.53) increased the risk of future symptoms of depression. “Job Strain” was not an adjusted risk factor for depression.

Conclusion

Our results support previous findings that bystanding to workplace bullying is related to future depressive symptoms.

Cost effectiveness of two rehabilitation programmes for neck and back pain patients: A seven year follow-up

The cost effectiveness of work-oriented rehabilitation for persons on long-term sick leave needs to be assessed. This prospective observational study presents a follow-up seven years after rehabilitation using two different evidence-based work-oriented regimens. Individuals on sick leave for neck and back pain were referred to two rehabilitation programmes in Sweden. The first programme was a relatively low-intensity programme based on orthopaedic manual therapy and exercise programme (OMTP). The second programme was a full-time multidisciplinary programme (MDP). The primary outcome was sickness absence seven years after intervention. Cost effectiveness was calculated on the basis of loss of production due to sickness absence. The results show that participants referred to MDP and with less than 60 sick days before rehabilitation have reduced sickness absence after intervention as compared to matched controls. This corresponds to a cost reduction of about 94,494 EUR per referred individual. Further, the results indicate that participants of the OMTP who have more than 60 sick days before rehabilitation have a statistically significant increased risk of disability pension. This means increased cost in terms of loss of production of 44,593 EUR per referred individual. The results of this study show that MPD but not OMTP achieves the goal of working life-oriented rehabilitation. A direct comparison between the rehabilitation programmes strengthened the assumption that long-term sickness absence prior to rehabilitation is associated with more days on sick leave after rehabilitation. This analysis also indicated the importance of participants' pain self-efficacy beliefs and recovery beliefs on rehabilitation outcome.

Determination of 2,4,6-trichloroanisole and 2,4,6-tribromoanisole in wine using microextraction in packed syringe and gas chromatography-mass spectrometry

A selective and fast method for the quantitative determination of 2,4,6-trichloroanisole (TCA) and 2,4,6-tribromoanisole (TBA) in wine was developed. Microextraction in packed syringe (MEPS) was optimized for the extraction and preconcentration of the analytes using extremely small volume samples (0.1-1 mL). For GC-EI-MS, the limit of detection (LOD) for red and white wine was in the range 0.17-0.49 microg L(-1) for TCA and TBA. In addition to GC-EI-MS both GC-NCI-MS and GC-HRMS were used to further improve both selectivity and sensitivity. The lowest LODs were achieved using GC-HRMS in the EI mode. In red and white wine samples the LODs were between 0.22-0.75 ng L(-1) for TCA and TBA. The reproducibility and linearity for the GC-HRMS method was good, with RSD-values of 4-10% for spiked red wine samples at 1 ng L(-1) and linearity with R (2) > 0.962 over a concentration range of 1 to 100 ng L(-1).

Downsizing of staff is associated with lowered medically certified sick leave in female employees

AIM

To determine whether changes in number of staff in work sites are associated with medically certified sick leave among employees with an increased risk of developing cardiovascular disease.

METHODS

The 5720 employees (aged 18-65) were from the WOLF study of cardiovascular risk factors in working men and women in greater Stockholm during the years 1992-95. From the medical examination a cardiovascular score was calculated for each participant. The WOLF study base was linked to a Statistics Sweden registry of economic and administrative activities. Sick leave spells lasting for at least 15 days during the calendar year following downsizing/expansion were identified for each subject.

RESULTS

In multiple logistic regression an increased likelihood of having no medically certified sick leave (15 days or more) was found in women during the year following both downsizing and expansion. These analyses were adjusted for age and cardiovascular score. A high cardiovascular risk score reduced the likelihood of having no medically certified sick leave. The inclusion of psychosocial work environment variables did not change the results markedly. Separate analyses of women with and without high cardiovascular score showed that downsizing had a more pronounced effect on reduced long term sick leave among those with high than among those without low cardiovascular score. There were no consistent findings in men.

CONCLUSIONS

There is evidence of a reduction of long term sick leave in women after downsizing and this is particularly evident among those with high cardiovascular score.

Analysis of low molecular weight organic acids in water with capillary zone electrophoresis employing indirect photometric detection

A capillary zone electrophoretic method for the analysis of low molecular weight carboxylic acids in water was developed. The application uses the chromophore trimellitic acid that allows for indirect photometric detection at 254 nm. Selectivity control by the addition of Ca2+ to the carrier electrolyte made possible a baseline resolved separation of 14 carboxylic acids. Good linearity and repeatability were obtained for both electrokinetic and hydrostatic injection modes. The usefulness of the method is demonstrated by the analysis of a snow sample.

Determination of nitrate and other water quality parameters in groundwater from UV/Vis spectra employing partial least squares regression

The use of UV/Vis spectroscopy in combination with partial least squares (PLS) regression for the simultaneous prediction of nitrate and non-purgeable organic carbon (NPOC) in groundwaters was evaluated. A model of high quality was obtained using first order derivative spectra in the range 200-300 nm. Inclusion of non-UV-absorbing constituents in the modeling procedure, i.e., chloride, sulfate, fluoride, total carbon (TC), inorganic carbon (IC), alkalinity, pH and conductivity was also evaluated. This model seemed to be useful for prediction of chloride, TC, IC, alkalinity and conductivity, while its ability to predict sulfate, fluoride and pH was poor. In conclusion, application of PLS regression, which requires neither filtration of samples nor addition of chemicals, is a promising alternative for fast interpretation of geochemical patterns of groundwater quality.

The relationship between depression and aerobic capacity in hemodialysis patients

Depression and a reduction in the performance of pleasant activities have been reported in patients with end-stage renal disease receiving hemodialysis therapy. The purpose of this study was to examine the relationship between depression and the patients' capacity to engage in physical activity. The patients' VO2max, or maximal oxygen consumption, was found to be positively associated with three standardized self-report measures of depression in a sample of 15 patients receiving hemodialysis. The clinical and theoretical implications of this finding are considered.

Cardiovascular and metabolic responses to submaximal exercise in hemodialysis patients

Eight chronic hemodialysis (cHD) patients and six healthy sedentary controls (C) were exercised for 60 minutes at 52 +/- 8% (cHD patients) and 48 +/- 4% (C) of their maximal oxygen consumption levels. Plasma lactate levels at rest and during exercise were comparable in both groups. Respiratory exchange ratios were lower in cHD patients, but they increased during exercise to levels comparable to those of the C group. Despite comparable heart rates at rest, exercise of similar intensity led to lower heart rates at 30 and 60 minutes in cHD patients compared to C (P less than 0.05). The cHD patients had higher systolic and mean arterial pressures at rest than did C (P less than 0.05), but during exercise the increments in systolic and mean blood pressures were lower in cHD patients than they were in C (P less than 0.05). In spite of these blunted cardiovascular responses, plasma catecholamines increased during exercise in both groups. Plasma glucose levels were similar in both groups during exercise in spite of significantly higher plasma levels of insulin and glucagon in cHD patients throughout the exercise session (P less than 0.01). These data demonstrate that chronic cHD patients can exercise at a modest intensity for a prolonged period of time without untoward cardiovascular or metabolic responses. Their poor exercise response does not appear to be related to an inadequate activation of the sympathoadrenal system.

Psychological effects of exercise training in hemodialysis patients

To assess the psychological effects of exercise training in hemodialysis patients 4 dialysis patients, matched by age, sex, and medical history with 4 controls, received psychological testing before and after a 6-month period of exercise training. The trained patients had a 28% improvement in graded exercise treadmill stress test duration and a 13% improvement in aerobic capacity. This was associated with a significant reduction in anxiety and depression (p less than 0.06), but no measurable change in these moods occurred in the control groups. These results suggest that exercise training may improve psychological functioning in dialysis patients.

The metabolic and psychological effects of exercise training in hemodialysis patients

The effect of exercise training on metabolic abnormalities and psychological function was assessed in seven hemodialysis patients. Their initial work capacity was low and improved after 8 months of training. Exercise was associated with a reduction in the dose of antihypertensive medications in four patients and a decrease in phosphate binder therapy in three patients. There was also a rise in hematocrit levels (% delta = 34 +/- 20%, P less than 0.03) and the hemoglobin concentration (% delta = 37 +/- 23%, P less than 0.05) of five males. Plasma glucose levels fell (-5 +/- 2%, P less than 0.05, n = 5) and the glucose disappearance rate improved (20 +/- 7%, P less than 0.02), while hyperinsulinism decreased (-36 +/- 20%, P less than 0.02, n = 5) during training. There was no change in body weight or diet. Exercise lowered plasma triglyceride levels (-41 +/- 28%, P less than 0.02, n = 6) and raised the high-density lipoprotein cholesterol concentration (20 +/- 21%, P less than 0.05, n = 6). Psychological testing (n = 4) demonstrated that exercise training was associated with an improvement in depression, hostility, anxiety, social interaction, and outlook for the future. These results suggest that exercise can improve some of metabolic abnormalities and psychological dysfunction which exists in some dialysis patients.

[Results of a prolonged program of physical training in patients with ischemic cardiopathology]

Training with resistant exercises has been proved to be beneficial for patients of ischemic cardiopathy. This kind of training increases working capacity, provided the exercise is maintained in the necessary threshold to avoid starting a chest angina. Nevertheless, there is no clear evidence of an increase in the blood flooding of the myocardio, the left ventricle function or the heart electric stability as a consequence of the said training. It's our opinion that the principal reasons for this lack of evidence are: a) insufficient research, b) the existence of technical difficulties for developing certain phases of the necessary research, and maybe that, c) some exercise programs are not sufficiently long and intense and to induce myocardial adaptation. The purpose of this study is to determine if a long program of physical exercise training could produce a better blood irrigation and ventricular function as well as restore the electric stability. This approach to the problem is justified by the recent finding of adequate methods which really and definitely answer these questions with the results obtained through properly controlled physical exercise.

Maximal O2 uptake of boys and girls -- ages 14--17

White high school girls (n = 120) and boys (n = 120) aged 14--17 years, selected from 9th, 10th, 11th and 12 grades of a northern, midwest U.S. high school performed running exercise on a motor driven treadmill for determinations of maximal O2 uptake (VO2 max). The mean VO max for all age groups was 40.8 +/- 4.0 and 54.7 +/- 5.6 ml/kg-min-1 for girls and boys respectively. The difference in VO2 max across age groups varied only from 40.2--41.2 ml/kg-min-1 for girls and 54.0-56.3 ml/kg-min-1 for boys. These differences were not significant (P greater than 0.05). The reported VO2 max data are compared with those reported in other studies for bicycle ergometer and treadmill excercise using similar age groups.