Comparing Genetic Variation among Latin American Immigrants: Implications for Forensic Casework in the Arizona- and Texas-Mexico Borderlands.

The humanitarian crisis on the US-Mexico border is a long-standing and evolving crisis in which nearly 8,000 deaths have been reported in the last two decades. These deaths are largely distributed across the Arizona-Mexico and Texas-Mexico border regions, where demographic trends for immigrants attempting to cross into the United States have shifted dramatically. The demographic change and volume of immigrants seeking shelter in the United States present new challenges for the forensic practitioners entrusted with the identification of individuals who lose their lives during the final segment of their journey. Within this border context, this study investigated how genetic variation inferred from forensically significant microsatellites can provide valuable information on regions of origin for unidentified remains at the group level. To explore how to mobilize these genetic data to inform identification strategies, the authors conducted a comparative genetic analysis of identified and unidentified immigrant cases from the Arizona- and Texas-Mexico contexts, as well as 27 other Latin American groups. Allele frequencies were utilized to calculate FST, and relationships were visually depicted in a multidimensional scaling plot. A Spearman correlation coefficient analysis assessed the strength and significance of population relationships, and an agglomerative clustering analysis assessed population clusters. Results indicate that Arizona-Mexico immigrants have the strongest relationship (>80%) with groups from El Salvador, Guatemala, Mexico, and an indigenous group from southern Mexico. Texas-Mexico immigrants have the strongest relationships (>80%) with groups from Belize, Colombia, Costa Rica, El Salvador, Guatemala, Honduras, and Nicaragua. These findings agree with, and are discussed in comparison with, previously reported demographic trends, population genetics research, and population history analyses. The authors emphasize the utility and necessity of coupling genetic variation research with a nuanced anthropological perspective for identification processes in the US-Mexico border context.

Dielectric-Screening Reduction-Induced Large Transport Gap in Suspended Sub-10 nm Graphene Nanoribbon Functional Devices.

The predicted quasiparticle energy gap of more than 1 eV in sub-6 nm graphene nanoribbons (GNRs) is elusive, as it is strongly suppressed by the substrate dielectric screening. The number of techniques that can produce suspended high-quality and electrically contacted GNRs is small. The helium ion beam milling technique is capable of achieving sub-5 nm patterning; however, the functional device fabrication and the electrical characteristics are not yet reported. Here, the electrical transport measurement of suspended ≈6 nm wide mono- and bilayer GNR functional devices is reported, which are obtained through sub-nanometer resolution helium ion beam milling with controlled total helium ion budget. The transport gap opening of 0.16-0.8 eV is observed at room temperature. The measured transport gap of the different edge orientated GNRs is in good agreement with first-principles simulation results. The enhanced electron-electron interaction and reduced dielectric screening in the suspended quasi-1D GNRs and anti-ferromagnetic coupling between opposite edges in the zigzag GNRs substantiate the observed large transport gap.

Clinical risk factors associated with intraoperative floppy iris syndrome: a prospective study.

PURPOSE: To evaluate the incidence of and factors associated with intraoperative floppy iris syndrome (IFIS) in patients undergoing cataract phacoemulsification. METHODS: In total, 319 eyes of 319 patients who underwent phacoemulsification with implantation of an intraocular lens (IOL) into the posterior chamber were included in this study. Direct injection of epinephrine into the anterior chamber was performed in all cases. The following patient information was collected: gender, age, axial length of the eye, presence of pseudoexfoliation syndrome, glaucoma, diabetes mellitus, hypertension, current use of medications including alpha1 adrenergic receptor antagonists (alpha1-ARAs), finasteride, and benzodiazepines, duration of intake of alpha1-ARAs and finasteride, and duration of the surgery. Patients were classified as IFIS or non-IFIS after the surgery. Univariate and multivariate logistic regression analyses were performed. RESULTS: The overall incidence of IFIS was 9.09% (29/319 eyes). The multivariate analysis revealed that tamsulosin use (P = 0.004), finasteride use (P = 0.014), and increasing age (P = 0.006) were significantly associated with IFIS. Male gender and benzodiazepine use were significantly associated with IFIS in the univariate analysis, but not in the multivariate analysis. The non-selective alpha1-ARA doxazosin was not found to be associated with IFIS. CONCLUSIONS: The findings suggest that finasteride use and aging are risk factors for IFIS and confirm the association of tamsulosin use with IFIS. Further, doxazosin appears to be a relatively safe drug with respect to the occurrence of IFIS.

Controlled fabrication of electrically contacted carbon nanoscrolls.

Carbon nanoscrolls (CNS) with their open ended morphology have recently attracted interest due to the potential application in gas capture, biosensors and interconnects. However, CNS currently suffer from the same issue that have hindered widespread integration of CNTs in sensors and devices: formation is done ex situ, and the tubes have to be placed with precision and reliability-a difficult task with low yield. Here, we demonstrate controlled in situ formation of electrically contacted CNS from suspended graphene nanoribbons with slight tensile stress. Formation probability depends on the length to width aspect ratio. Van der Waals interaction between the overlapping layers fixes the nanoscroll once formed. The stability of these CNSs is investigated by helium nano ion beam assisted in situ cutting. The loose stubs remain rolled and mostly suspended unless subject to a moderate helium dose corresponding to a damage rate of 4%-20%. One CNS stub remaining perfectly straight even after touching the SiO2 substrate allows estimation of the bending moment due to van der Waals force between the CNS and the substrate. The bending moment of 5400 eV is comparable to previous theoretical studies. The cut CNSs show long-term stability when not touching the substrate.

Nitrogen Gas Field Ion Source (GFIS) Focused Ion Beam (FIB) Secondary Electron Imaging: A First Look.

The recent technological advance of the gas field ion source (GFIS) and its successful integration into systems has renewed the interest in the focused ion beam (FIB) technology. Due to the atomically small source size and the use of light ions, the limitations of the liquid metal ion source are solved as device dimensions are pushed further towards the single-digit nanometer size. Helium and neon ions are the most widely used, but a large portfolio of available ion species is desirable, to allow a wide range of applications. Among argon and hydrogen, $${\rm N}_{2}^{{\plus}} $$ ions offer unique characteristics due to their covalent bond and their use as dopant for various carbon-based materials including diamond. Here, we provide a first look at the $${\rm N}_{2}^{{\plus}} $$ GFIS-FIB enabled imaging of a large selection of microscopic structures, including gold on carbon test specimen, thin metal films on insulator and nanostructured carbon-based devices, which are among the most actively researched materials in the field of nanoelectronics. The results are compared with images acquired by He+ ions, and we show that $${\rm N}_{2}^{{\plus}} $$ GFIS-FIB can offer improved material contrast even at very low imaging dose and is more sensitive to the surface roughness.

Partial hydrogenation induced interaction in a graphene-SiO2 interface: irreversible modulation of device characteristics.

The transformation of systematic vacuum and hydrogen annealing effects in graphene devices on the SiO2 surface is reported based on experimental and van der Waals interaction corrected density functional theory (DFT) simulation results. Vacuum annealing removes p-type dopants and reduces charged impurity scattering in graphene. Moreover, it induces n-type doping into graphene, leading to the improvement of the electron mobility and conductivity in the electron transport regime, which are reversed by exposing to atmospheric environment. On the other hand, annealing in hydrogen/argon gas results in smaller n-type doping along with a decrease in the overall conductivity and carrier mobility. This degradation of the conductivity is irreversible even the graphene devices are exposed to ambience. This was clarified by DFT simulations: initially, silicon dangling bonds were partially terminated by hydrogen, subsequently, the remaining dangling bonds became active and the distance between the graphene and SiO2 surface decreased. Moreover, both annealing methods affect the graphene channel including the vicinity of the metal contacts, which plays an important role in asymmetric carrier transport.

Large-scale nanoelectromechanical switches based on directly deposited nanocrystalline graphene on insulating substrates.

The direct growth of graphene on insulating substrate is highly desirable for the commercial scale integration of graphene due to the potential lower cost and better process control. We report a simple, direct deposition of nanocrystalline graphene (NCG) on insulating substrates via catalyst-free plasma-enhanced chemical vapor deposition at relatively low temperature of ∼800 °C. The parametric study of the process conditions that we conducted reveals the deposition mechanism and allows us to grow high quality films. Based on such film, we demonstrate the fabrication of a large-scale array of nanoelectromechanical (NEM) switches using regular thin film process techniques, with no transfer required. Thanks to ultra-low thickness, good uniformity, and high Young's modulus of ∼0.86 TPa, NCG is considered as a promising material for high performance NEM devices. The high performance is highlighted for the NCG switches, e.g. low pull-in voltage <3 V, reversible operations, minimal leakage current of ∼1 pA, and high on/off ratio of ∼10(5).

Influence of risk-taking health behaviours of adolescents on cervical cancer prevention: a Hungarian survey.

An anonymous questionnaire survey was conducted among the Hungarian adolescents to establish their use of tobacco, alcohol and drugs in relation to sexual behaviours, knowledge of human papillomavirus (HPV) and cervical cancer, and beliefs and attitudes towards screening and vaccination. Results indicated that adolescent risk-taking health behaviours correlate with risky sexual behaviours. As risk-taking behaviours do not correlate with a better awareness of the risk associated with HPV infection, it is of crucial importance that HPV/cervical cancer preventing educational programmes shall be sensitive to this 'vulnerable' population and draw the attention of these adolescents to their increased risk of sexually transmitted diseases and undesired pregnancies. Well-designed behavioural change interventions may be effective when in addition to providing adolescents (both men and women) with clear information about the implications of an HPV infection, they also aim to improve safer sex behaviours: consistent condom usage, limiting the number of sex partners, as well as encouraging regular participation in gynaecological screenings and uptake of the HPV vaccine. As this study population demonstrated positive attitudes towards the primary and secondary prevention of cervical cancer, the free HPV vaccination for the 12-13-year-old girls in Autumn 2014 will hopefully increase the currently low uptake of the vaccine in Hungary.

Endosseous Fixation Device for Lapidus Arthrodesis: Technique, Early Experience, and Comparison With Crossed Screw Fixation.

First metatarsal cuneiform joint arthrodesis has been commonly used since the early 1900s for definitive treatment of a variety of conditions involving the medial column of the foot. Early applications of this procedure resulted in a relatively high rate of complications, including malunion and nonunion. We retrospectively examined a novel method of fixation involving an endosseous implant with a nonporous, rough exterior surface and compared it with the traditional crossed screw fixation, considered the standard of care for the procedure. Twenty-one feet in 19 patients served as the control group with crossed screws, and 18 feet in 17 patients served as the trial group using the study device. Null hypothesis testing was used to compare the outcomes parameters between the comparative groups. Postoperatively, the patients were allowed to walk in a prefabricated, removable, below-the-knee cast boot at a mean of 48.3 ± 8.2 days in the control group and 24.4 ± 9.7 days in the trial group. These differences were highly significant (p < .0001). Postoperatively, the patients were allowed to walk in a stiff-soled shoe at a mean of 65.2 ± 8.4 days in the control group and 49.7 ± 19.2 days in the trial group. These differences were also statistically significant (p = .0020). The patients in the control group required revision surgery in 7 of 21 procedures (33%), with 2 patients developing nonunion (9.5%). Only 1 patient in the trial group required revision surgery (5.8%), and no patient developed nonunion. From these results, we believe that the endosseous trial implant is a reliable option for fixation of the first metatarsal cuneiform arthrodesis procedure and might allow for earlier weightbearing with fewer postoperative complications.

Specific Inhalation Challenge in Persulfate Asthma.

Specific inhalation challenge (SIC) may be considered the 'gold standard' for the diagnosis of occupational asthma due to persulfate salts. The aim of the study was to develop a safe SIC protocol. Between 2003 and 2014, eight patients with suspected occupational asthma due to persulfate salts were examined (7 females, all hair-dressers). SIC was done with a dosimeter and a nebulizer using ammonium persulfate dissolved in phosphate buffer. Until 2009, a four-step-protocol (doses: 0.0004, 0.0045, 0.045, 0.45 mg; cumulative: 0.5 mg) was used, afterwards a six-step-protocol (doses: 0.0004, 0.0018, 0.007, 0.028, 0.113, 0.45 mg; cumulative: 0.6 mg). With each SIC protocol, four subjects were tested. Skin prick tests with ammonium persulfate (20 mg/mL) were performed in all and patch tests in four subjects. In total, four subjects showed a positive SIC, two with each protocol. All subjects showed an isolated late reaction. The greatest decrease of volume in 1 s was 35 % about 3.5 h after the last inhalation (four-step-protocol). Skin prick test with ammonium persulfate was positive in one SIC positive (2 mm wheal) and in two SIC negative patients (3 and 4 mm wheal). All four subjects tested with patch tests showed a positive reaction; three of them were SICpos. We recommend to include patch-testing in the diagnosis of suspected occupational asthma due to persulfate salts. Isolated late asthmatic reactions may occur after SIC. The proposed six-step SIC protocol was safe in this limited number of subjects.

[Retroperitoneal perforation of duodenum - surgical approach]. / Zaotrzewnowa perforacja dwunastnicy - postEpowanie chirurgiczne.

Retroperitoneal perforation of the duodenum, caused by abdominal trauma, endoscopic examination or diverticulitis, is a serious clinical problem, because of it's lack of specific symptoms. Surgical treatment is often performed in sepsis. That is why the knowledge of adequate techniques is crucial for surgeons. We would like to present our model of surgical approach, based on several trauma center's cases. Among the methods and techniques presented we emphasize the duodenal by-pass with bile duct drainage. Post-op cases of gastrojejunal anastomosis' bleeding prompt to implement a selective vagotomy, which however requires further studies.

Human papillomavirus infections among Hungarian female sex workers.

The purpose of this study was to assess the human papillomavirus (HPV) prevalence in cervical, oropharyngeal and anal samples of the high-risk population of Hungarian female sex workers (FSWs). HPV testing of swab specimens from FSWs (n = 34) using polymerase chain reaction (PCR) methodology was performed. Results were compared with control group (n = 52) matched for age. Questionnaires were used to obtain data regarding participants' sexual behaviour. Data were analysed using SPSS. HPV DNA was detected in at least one location in a great majority of FSWs (82.4%), compared with 46.2% of the general female population (P < 0.05). Both the cervical and the anal samples of sex workers showed higher infection rates than those of controls (64.7% vs. 34.6% and 50.0% vs. 15.4%, respectively, P < 0.05). High-risk HPV prevalence was also significantly higher in sex workers (55.9% vs. 25.0%, P < 0.05). A significantly higher proportion of FSWs had a history of genital warts (26.5% vs. 3.8%, P < 0.05). The results suggest that condom use may not result in adequate protection from HPV infection. The high infection rates among FSWs should be viewed as a priority group for HPV and cervical cancer prevention programmes since they are sources of HPV infection for the general population.

Exercise in cold air and hydrogen peroxide release in exhaled breath condensate.

Athletes have changes in the lung epithelial cells caused by inhalation of cold and dry air. The exhaled breath condensate contains a number of mediators from the respiratory system and H(2)O(2) is described as a marker of airways inflammation. The aim of this study was to determine the influence of exercise combined with cold air on the H(2)O(2) release in the exhaled breath. Twelve males (23.1 ± 1.5 years) were randomly assigned at 2 different days (1 day rest) to perform a 50 min run (75-80% of their max. heart rate) under normal (N) laboratory (18.1 ± 1.1°C) or cold (C) field condition (-15.2 ± 3.1°C). Before and immediately after each run, the EBC was collected under laboratory conditions and was analyzed amperometrically. Prior to the two runs, H(2)O(2) concentrations were 145.0 ± 31.0 (N) and 160.0 ± 49.1 nmol/L (C) and theoretical release was 70.3 ± 37.1 (N) and 82.6 ± 27.1 pmol/min (C) (p > 0.05). After each run, H(2)O(2) concentration increased significantly to 388.0 ± 22.8 nmol/L (N) and 622.1 ± 44.2 nmol/L (C) (p < 0.05), along with an increase in the theoretical release: 249.2 ± 35.7 pmol/min (N) and 400.9 ± 35.7 pmol/min (C) (p < 0.05). We conclude that release of H(2)O(2) into the EBC takes place under both resting conditions and after exercise. The concentration and release of H(2)O(2) increased after exercise in cold air compared to resting and laboratory conditions, which points to an increase in inflammatory and oxidative stress.

Lung function at age 18-25 years: a comparison of different reference value systems.

The anthropometrical data of the Caucasian population have significantly changed within the last five decades. The European Community for Coal and Steel (ECCS) assumes a plateau phase and recommends the entry of 25 years old for calculation of reference values in this age range. The question arises if the commonly used reference recommendations for lung function of the ECCS can still be accepted. In the present study standardized spirometric lung function tests were performed by pneumotachography, recording lung volumes and flows (MasterScreen Pneumo, CareFusion, Höchberg) in asymptomatic nonsmoking subjects (202 females, 201 males), aged between 18 and 26, according to the ATS/ERS criteria. The results were compared with the reference recommendations of ECCS, SAPALDIA, LuftiBus, and Bochum (only males). All absolute lung function values showed a correlation (p< 0.05) with height. With respect to FVC and FEV(1), SAPALDIA and Bochum reference values were comparable and close to a 100 (range 97.6-101.4) %pred, whereas both ECCS and LuftiBus showed higher values (range 103.6-109.9%pred). The FEV(1)/FVC ratio was close to a 100 (range 97.6-101.7) %pred in all reference systems, whereas flows showed a wide variability between the reference systems (77.1-114.6%pred), single flows (e.g., 96.9-114.2%pred for MEF(50)) and males/females (males: 93.6-114.6%pred; females: 77.1-107.9%pred). We conclude that SAPALDIA reference values for FVC and FEV(1) should be used, as they better represent lung function in the age group. ECCS and LuftiBus reference values are appreciably (4-10%) lower. Differences between reference systems were less important for the FEV(1)/FVC ratio and lung flows.

Incomplete knowledge--unclarified roles in sex education: results of a national survey about human papillomavirus infections.

The purpose of this study was to evaluate the awareness of human papillomavirus (HPV) infections both in male and female adults in Hungary. A self-administered, anonymous questionnaire was completed by 785 college students and parents between January and May, 2009. The results were analysed by gender and age. Participants' knowledge about HPV and HPV-associated conditions was relatively incomplete. One-third of the respondents had never heard about HPV prior to the survey. Almost half of the respondents (42%) thought that the only sexual way of spreading HPV was vaginal intercourse, while the role of skin-to-skin contact was disregarded (6%). More than one-third of the participants (38%) believed that condoms give full protection from HPV infection. Encouragingly, the majority of respondents (64%) were open to further information about sexually transmitted diseases. The most trusted sources of information were health professionals. When talking about children, parents attributed the major role in delivering information about sexually transmitted diseases to schools. Primary prevention through carefully planned educational programmes may further raise the awareness about HPV-associated conditions, thus reducing the comparatively high mortality of cervical carcinoma in Hungary.

Lung function in our aging population.

UNLABELLED: AIMS OF INVESTIGATION: The chronological age of the Caucasian population and their anthropometrical data have significantly changed within the last five decades. Therefore the question arises whether or not the commonly used reference values of the European Community (ECCS) for lung function may still be accepted today. Since these values were obtained in the 1960s from subjects in a limited age range. For the elderly, the measured values are deduced by extrapolation beyond the range of reference equations which had been obtained in a different population. Therefore decisions concerning elderly and smaller subjects concerning remuneration due to impaired lung function after industrial exposure on the basis of EGKS values are questionable. METHODS: Lung function tests were performed by pneumotachography, recording static lung volumes and flow-volume-curves in 262 asymptomatic non smoking males, aged 20 to 90 years. Measurements were performed with the MasterLab, or PneumoScreen systems (CareFusion, Höchberg). RESULTS were compared to the reference values of ECCS, SAPALDIA and LuftiBus. - RESULTS: For simplicity analysis of age and height dependence of investigated respiratory parameters (VC, FVC, FEV⊂1, FEV⊂1%FVC, PEF, MEF⊂75,50,25) can be described by linear functions (y = a * height ? b * age + c). The forced expiratory vital capacity, FVC, was calculated by FVC = 0.0615*H - 0.0308*A - 4.673; r = 0.78. Mean FVC for younger subjects was found to be 104.7 ± 10.7% of the ECCS reference values and 96.5 ± 11.8 % in older subjects. For most parameters investigated linear regressions on age were steeper than described by the ECCS reference values. The regression of lung function to height largely follows the ECCS prescriptions. SUMMARY: Bochum lung function values of younger healthy subjects were higher compared to the reference values of the ECCS and showed a steeper age descent. The alternatively discussed reference values of the SAPALDIA-, or LuftiBus-Study are higher, but do not cover all necessary parameters and/or the age range. A multi centre study for contemporary reference values is recommended.

[Efficiency as a new parameter of physical fitness of patients in 6-minute-walk-test]. / Effizienz als ein neuer Parameter zur Objektivierung der körperlichen Leistungsfähigkeit mittels 6-Minuten-Gehtest.

UNLABELLED: AIMS OF THE INVESTIGATION: The 6-minute-walk-test (6-MWT) is an effective tool for measuring physical fitness in elderly patients. The increased walking distance is taken as a parameter for improved physical conditions. Frequently an unaltered walking distance is found after participation in a rehabilitation measure, but heart rate is significantly lower in the second challenge, indicating an improved physical fitness. This positive effect is not recognized when only the walking distance is considered. METHODS: We therefore carried out a retrospective analysis of the 6-MWT tests performed by 303 male patients (69.2 ± 8.7 years) before and after 3-4 weeks of clinical rehabilitation. Instrumented by a mobile pulse oximeter for recording oxygen saturation and heart rate, patients were instructed at the outset and at the end of their rehabilitation stay to walk as fast as they could during 6 min. Measurements were performed every 30 s and printed. A new parameter, efficiency (E = S/6/f (C)) was introduced: the ratio of the walking distance, S, divided by 6 min and divided by the mean heart frequency, f (C) (beats/minute). RESULTS: The patients group walked 351 ± 79 m at 106.2 ± 12.7 beats/min in the initial 6-MWT and 362 ± 76.0 m at a heart rate of 104.0 ± 12.2 beats/min in the final test. Along with the increase in walking distance, efficiency E increased from 0.56 ± 0.13 m/beat to 0.59 ± 0.12 m/beat. Efficiency significantly correlates with the walking distance (p < 0.01). 54 patients (18%) had an increased efficiency in the final test at the end of rehabilitation although they walked a shorter distance compared to the initial test value: they walked with a lower heart frequency. CONCLUSIONS: The patient's performance of the second walk test with an unchanged distance at a lower heart frequency reveals an improved physical fitness. This is solely described by an increase of the parameter of efficiency, E. Calculation of this parameter delivers a quantification of the effect of exercise training irrespective of the patient's cooperation. Efficiency, hence, is a meaningful complement to the sole consideration of the distance walked in the assessment of physical fitness as a benefit of rehabilitation.

Pulsatile ocular blood flow in subjects with sleep apnoea syndrome.

INTRODUCTION: The aim of the study was to determine the correlation between pulsatile ocular blood flow (POBF) and sleep apnoea syndrome (SAS). MATERIAL AND METHODS: Patients were recruited from those who underwent polysomnography in the "Sleep Unit" of the physiology department (Medical University, Lodz, Poland). A total of 52 Caucasian patients, 34 with SAS and 18 age- and gender-matched controls, were included in the study. Comprehensive ophthalmic examination included the pulsatile ocular blood flow (POBF) measurements, disc analysis with Heidelberg Retina Tomograph II and Oculus Centerfield computerized perimetry as well as the best visual acuity, a slit lamp and indirect ophthalmoscopic evaluation of anterior and posterior segments and applanation tonometry. RESULTS: The observed prevalence of glaucoma in SAS patients was 5.9% (2 of 34). The mean values of POBF were 1069.21 ±235.94 µl/min in the SAS group and 1061.78 ±174.63 µl/min in the control group. The study revealed that the differences of mean POBF between the SAS patients and the control group were not statistically significant: Mann-Whitney U-test p > 0.05. No correlations were found between sleep apnoea syndrome and mean intraocular pressure (IOP), mean retinal nerve fibre layer (RNFL) thickness and visual field mean defect (MD). CONCLUSIONS: No correlation was found between pulsatile ocular blood flow and sleep apnoea syndrome. Although some previous studies found an association between IOP, MD, RNFL thickness and sleep apnoea syndrome, our study did not confirm that. However, a high prevalence of glaucoma was found among SAS patients in Poland.

[A new procedure for the estimation of physical fitness of patients during clinical rehabilitation using the 6-minutes walk test]. / Zur Reproduzierbarkeit der Wegstrecken beim 6-Minuten-Gehtest im Rahmen eines stationären Rehabilitationsaufenthaltes.

UNLABELLED: AIMS OF THE INVESTIGATION: The repetition of the 6-minutes walk test (6 MWT) in older patients is frequently performed in order to document the maximal walking distance, although it is not recommended in any guidelines on exercise tests and although there is common consent to save clinical resources in terms of time and staff. Therefore, we have examined whether and to what extent the repetition of the walk tests helps patients to get more familiar with this kind of exercise test. Thus the acquired physiological data should reliably describe the physical fitness of the patients at the beginning and at the end of their clinical rehabilitation. METHODS: 35 patients performed their walk tests before and after 3 - 4 weeks of clinical rehabilitation. Each test has been repeated after one hour of recovery. The patients were instructed to walk during 6 minutes as fast as possible. They were equipped with a mobile pulse oximeter for recording oxygen saturation and heart rate. The distance, S, and the heart rate, fc, were measured. Measurements were performed every 30 seconds and recorded. The efficiency, E (E = S/6/fc), was calculated as the ratio of distance per minute and the mean heart rate during the test. RESULTS: In the first test the patients walked 416 +/- 63 m at a heart rate of 104.7 +/- 15.7 beats/min, in the first repeated test 454 +/- 71 m at a heart of 106.3 +/- 17.4 beats/min. In the second test, after clinical therapy, they walked 438 +/- 58 m at a heart rate of 106.3 +/- 17.4 beats/min, in the second repeated test 473 +/- 56 m at 108.6 +/- 13.2/min. The difference of the walking distances of the tests at the entrance were found to be 38.4 +/- 26.2 m (+ 9.3 +/- 6.2%), at the end of clinical rehabilitation 35 +/- 26 m (+ 8.4 +/- 6.4%). Both differences are found to be independent from the distance of the first test. They are not significantly different. The efficiency was not significantly different in the initial and final test (0.673 +/- 0.129 and 0.689 +/- 0.085 m/beat, respectively). The difference in efficiency, when repeating the tests at the beginning, was: 0.053 +/- 0.062 m/beat; at the end of the rehabilitation: 0.042 +/- 0.047 m/beat. They are found to be similar. CONCLUSIONS: The distances the patients walked in the repeated tests at the entrance and at the end of their clinical rehabilitation were, besides the calculated efficiency, E, significantly increased. However, the increases in distance and efficiency are identical on both occasions, therefore the repetition delivers no further information. The test should be performed without repetitions in clinical routine investigations. The patient's performance in the second walk test with an unchanged distance at a lower heart rate reveals an improved physical fitness. This is solely described by an increase of efficiency, E. Therefore the introduction of E is a suitable measure of the quantified effect of exercise training, even if the patient is not cooperative during the tests. E is proved to be a suitable estimation for the assessment of physical fitness as a benefit of clinical rehabilitation.

Measurements of lactate in exhaled breath condensate at rest and after maximal exercise in young and healthy subjects.

Arterial lactate concentrations, taken as indicators of physical fitness, in athletes as well as in patients with cardio-respiratory or metabolic diseases, are measured invasively from arterialized ear lobe blood. Currently developed micro enzyme detectors permit a non-invasive measurement of hypoxia-related metabolites such as lactate in exhaled breath condensate (EBC). The aim of our study is to prove whether this technology will replace the traditional measurement of lactate in arterialized blood. Therefore, we determined the functional relation between lactate release in EBC and lactate concentration in blood in young and healthy subjects at rest and after exhausting bicycle exercise. During resting conditions as well as after exhausting bicycle exercise, 100 L of exhaled air along with blood samples from the ear lobe was collected after stationary load conditions in 16 healthy subjects. EBC was obtained by cooling the expired air volume with an ECoScreen I (FILT GmbH, Berlin) condenser. The analysis was performed within 90 min using an ECoCheck ampere meter (FILT GmbH, Berlin). Lactate measurements were performed using a bi-enzyme sensor after lactate oxidase-induced oxidation of lactate to pyruvate and H2O2. The rates of lactate release via the exhaled air were calculated from the lactate concentration, the volume and the collection time of the EBC. The functional relation of lactate release in exhaled air and lactate concentration of arterial blood was computed. At rest, the mean lactate concentration in arterialized blood was 0.93 ± 0.30 mmol L(-1). At a resting ventilation of 11.5 ± 3.4 L min(-1), the collection time for 100 L of exhaled air, Ts, was 8.4 ± 2.9 min, and 1.68 ± 0.40 mL EBC was obtained. In EBC, the lactate concentration was 21.4 ± 7.7 µmol L(-1), and the rate of lactate release rate in collected EBC was 4.5 ± 1.7 nmol min(-1). After maximal exercise load (220 ± 20 W), the blood lactate concentration increased to 10.9 ± 1.8 mmol L(-1) and the ventilation increased to 111.6 ± 21.4 L min(-1). The EBC collection time decreased to 3.9 ± 1.9 min, and 1.20 ± 0.44 mL EBC were obtained in the recovery period after termination of exercise. The lactate concentration in EBC increased to 40.3 ± 23.0 µmol L(-1), and the lactate release in EBC increased to 13.6 ± 8.6 nmol min(-1) (p < 0.01). Assuming a volume of 4.3 mL water in 100 L of exhaled air (saturated with water at 37 °C), we calculated a lactate release at rest of 11.5 ± 4.3 nmol min(-1) and 48.6 ± 30.7 nmol min(-1) (p < 0.01) after exhausting exercise. Detectable releases of lactate in exhaled breath condensate were found already under resting conditions. During exhausting external load on a bicycle spiroergometer, an increase in the lactate concentration was found in arterialized blood along with an increased lactate release in EBC. The correlation between expiratory lactate release via EBC and lactate concentration in arterialized blood is studied in pursuing investigations.