Acute oral alkali citrate load in healthy humans — Response of blood and urinary citrate,mineral metabolism,and factors related to stone formation

Summary In ten healthy volunteers (/=5/5) the effects of two doses (2.5 and 5.0 g) of orally ingested alkali citrate (AC) on serum citrate, variables of mineral metabolism in serum, the urinary excretion of citrate, sodium and minerals were studied and compared with the effects of an oral vehicle load. Also, phosphate crystalluria and the supersaturation of several stone forming phases in urine were evaluated under all loads. The data allow to conclude that 1) the rise in serum citrate may result from citrate absorbed intestinally under AC;2) systemic metabolic alkalosis is not detectable with the chosen AC doses but may be reflected by the more alkaline urinary pH and a higher citrate excretion; 3) mineral metabolism, serum ionized calcium, parathormone, calcitonin and urinary cyclic AMP included, are more or less stable under acute loads of AC;4) postprandial phosphate crystalluria is more pronounced with increasing AC, but despite this the direct correlation with the supersaturation of hydroxyapatite is progressively weakened with both doses AC suggesting that the inhibitory effects of this drug may dominate over its effects upon initiation of precipitation.Parts of this work were presented at the European Urolithiasis Symposium, held in Vienna, from March 21 to 23, 1985     

Comparison of three mobile devices for measuring R–R intervals and heart rate variability: Polar S810i, Suunto t6 and an ambulatory ECG system

The first aim of this study was to compare an ambulatory five-lead ECG system with the commercially available breast belt measuring devices; Polar S810i and Suunto t6, in terms of R–R interval measures and heart rate variability (HRV) indices. The second aim was to compare different HRV spectral analysis methods. Nineteen young males (aged between 22 and 31 years, median 24 years) underwent simultaneous R–R interval recordings with the three instruments during supine and sitting rest, moderate dynamic, and moderate to vigorous static exercise of the upper and lower limb. For each subject, 17 R–R interval series of 3-min length were extracted from the whole recordings and then analyzed in frequency domain using (1) a fast Fourier transform (FFT), (2) an autoregressive model (AR), (3) a Welch periodogram (WP) and (4) a continuous wavelet transform (CWT). Intra-class correlation coefficients (ICC) and Bland–Altman limits of agreement (LoA) method served as criteria for measurement agreement. Regarding the R–R interval recordings, ICC (lower ICC 95% confidence interval >0.99) as well as LoA (maximum LoA: −15.1 to 14.3 ms for ECG vs. Polar) showed an excellent agreement between all devices. Therefore, the three instruments may be used interchangeably in recording and interpolation of R–R intervals. ICCs for HRV frequency parameters were also high, but in most cases LoA analysis revealed unacceptable discrepancies between the instruments. The agreement among the different frequency transform methods can be taken for granted when analyzing the normalized power in low and high frequency ranges; however, not when analyzing the absolute values.     

Arginine inhibits hemostasis activation.

BACKGROUND: The diagnosis and the therapy of in vivo hemostasis activation is of great clinical importance. Artefactual changes of the hemostasis (i.e., coagulation or fibrinolysis) in vitro have to be prevented. Usual in vitro anticoagulation by sodium citrate does not fully inhibit coagulation--or fibrinolysis--activation. Therefore, there is need for a simple physiologic inhibitor of hemostasis activation both in diagnosis and therapy of hemostasis activation. METHODS: Whole blood clotting time (WBCT), prothrombin time (PT), activated partial thromboplastin time (APTT), in vitro bleeding test closure time (IVBT-CT), and whole blood aggregometry (WBA) were determined in normal human blood or plasma, supplemented with increasing concentrations of L-arginine or guanidine. RESULTS: Arginine in concentrations of 5-100 mM inhibited the WBCT, PT, APTT, IVBT-CT, and WBA. Arginine (50 mM) resulted in a two-fold prolongation of WBCT, PT, or IVBT-CT (the anti-epinephrine action is superior to the anti-ADP action), a four-fold prolongation of APTT or a 60% inhibition of WBA. CONCLUSION: L-Arginine (or guanidine) inhibited the activation of hemostasis. Arginine might be used as hemostasis stabilizer both in the diagnosis and therapy of hemostasis activation. The usage of arginine as an in vitro hemostasis inhibitor might be indicated in the diagnosis of hemostasis activation, as occurring in pharmacological thrombolysis or disseminated intravascular coagulation (DIC). The storage of blood or blood products might be improved by arginine stabilization. The amino acid (and nitric oxide precursor) L-arginine could be an interesting new pharmacologic agent to inhibit a pathologic hemostasis activation.     

Stress and fitness monitoring embedded on a modern telematics platform

Lack of regular physical activity and high stress levels are the leading causes of several illnesses. There is thus a real need for a personal low-cost and mobile monitoring solution over extended periods to prevent health risks. Based on the above fact, this article presents a system capable of estimating and monitoring both stress and fitness levels without a physical consultation of a medical specialist. The system consists of three main subcomponents: a mobile real-time acquisition of physiological as well as subjective data, an expert model for stress and fitness estimations based on physiological signals collected from wireless vital sensors, and a secure and scalable telematics platform on which the entire system is embedded. Features and tasks performed by the telematics platform will be presented. The experimental part of the work involved a representative number of subjects. Results for 110 subjects whose fitness levels were assessed at different periods of the year and 50 individuals whose stress scores were assessed at different times of the day showed a high correlation of the estimated values with the true ones. The application of such a low-cost monitoring system will improve the quality of service in preventive medicine.     

Intersession reliability of the interpolated twitch technique applied during isometric,concentric, and eccentric actions of the human knee extensor muscles

Introduction: Although it has been shown that voluntary activation (%VA) of the knee extensors during isometric contractions can be reliably assessed with the interpolated twitch technique, little is known about the reliability of %VA during concentric and eccentric muscle actions. Therefore, relative and absolute intersession reliability of quadriceps muscle's %VA during different contraction modes was determined. Methods: After a familiarization session, 21 participants (17 males, 25 ± 2 yrs) completed two testing sessions. Paired supramaximal electrical stimuli were administered to the femoral nerve during isometric, concentric, eccentric MVCs, and at rest to assess %VA (stimuli were applied at 70° knee flexion). Results and discussion: Data indicate that %VA of the knee extensors can be reliably measured during isometric [intraclass correlation coefficient (ICC) = 0.89, coefficient of variation (CV) = 4.1%], concentric (ICC = 0.87, CV = 6.6%), and eccentric muscle actions (ICC = 0.86, CV = 7.0%). Muscle Nerve 56 : 324–327, 2017     

Drought stress variability in ancient Near Eastern agricultural systems evidenced by δ13C in barley grain

The collapse and resilience of political systems in the ancient Near East and their relationship with agricultural development have been of wide interest in archaeology and anthropology. Despite attempts to link the archaeological evidence to local paleoclimate data, the precise role of environmental conditions in ancient agricultural production remains poorly understood. Recently, stable isotope analysis has been used for reconstructing site-specific ancient growing conditions for crop species in semiarid and arid landscapes. To open the discussion of the role of regional diversity in past agricultural production as a factor in societal development, we present 1.037 new stable carbon isotope measurements from 33 archaeological sites and modern fields in the geographic area of the Fertile Crescent, spanning the Aceramic Neolithic [10,000 calibrated years (cal) B.C.] to the later Iron Age (500 cal B.C.), alongside modern data from 13 locations. Our data show that drought stress was an issue in many agricultural settlements in the ancient Near East, particularly in correlation with the major Holocene climatic fluctuations, but its regional impact was diverse and influenced by geographic factors. Although cereals growing in the coastal areas of the northern Levant were relatively unaffected by Holocene climatic fluctuations, farmers of regions further inland had to apply irrigation to cope with increased water stress. However, inland agricultural strategies showed a high degree of variability. Our findings suggest that regional differences in climatic effects led to diversified strategies in ancient subsistence and economy even within spatially limited cultural units.The emergence and decline of early civilizations is intrinsically tied to agricultural surplus production, either enabling a focus on technological progress and the accumulation of wealth or, in the case of insufficient yield, leading to hunger, violence, and war.Although the role of agriculture in state building is uniformly accepted, the role of climate in agricultural production and societal development in the ancient Near East has been explained in radically different ways, closely related to the scientific background and the humanistic mindset of the individual researchers. Environmental versus cultural determinism are competing explanatory models of societal change (1, 2). However, neither model adequately accommodates the multicausal structure of responses of human societies to high variability in natural and process-related effects (3, 4).Local effects of global Holocene climatic fluctuations have been recognized with diverse magnitudes in paleoclimate proxy archives in the Near East (5–11). Among these climatic shifts, the 4200 B.P. event has been most intensively discussed by archaeologists and geographers, who have linked this fluctuation to the decline of state systems at the end of the Early Bronze Age (12–16). Societal collapse has been supported by evidence of population movements into more favorable regions (17, 18). Agricultural production at the transition from the Early to the Middle Bronze Age shows regionally limited changes in preferred crop species, which are interpreted as being related to increased aridity at the end of the third millennium calibrated years (cal) B.C. (4, 19).Although paleoenvironmental studies and archaeological records imply that droughts had a major impact on ancient agricultural yields (20), these data only indirectly reflect agricultural production. At present, the only way to directly link climatic fluctuations and agricultural productivity in the past is through stable carbon isotope analysis of archaeological plant remains. This method is an established tool for identifying ancient environmental conditions for plant growth in arid to semiarid environments because δ¹³C values in cereals provide a drought-stress signal when the amount of water received during the grain-filling period is low (21–26). Carbon fixation during photosynthesis leads to typical ranges of δ¹³C between −28‰ and −25‰ in modern barley, which is a C3 plant (27). In case of drought stress, the plants protect themselves from dehydration through closure of the stomata, which leads to a relative enrichment of the heavy vs. the light carbon isotope in the plant tissues (22).Because the δ¹³C signal reflects seasonal fluctuations in moisture conditions, we undertook stable carbon isotope analysis of archaeological and modern barley grains to assess the impact of known Holocene climatic fluctuations on agricultural and economic dynamics in ancient societies. Here, we present a reconstruction of the effects of past climatic fluctuations on cereal agriculture in the ancient Near East, expressed as chronological sequences and spline interpolation maps of isolines of stable carbon isotope means and minima. Our calculations are based on 1.037 δ¹³C measurements from individual barley grains derived from 33 archaeological sites and 13 modern locations (Fig. 1, Table S1, and Materials and Methods).Open in a separate windowFig. 1.Sampling locations in northern Mesopotamia and the Levant and chronology of barley grains providing δ¹³C measurements. Note that the only sites listed are those that appear in the map section: (site 1) Abu Hamid, (site 2) Ain Rahub, (site 6) Dilkaya Höyük, (site 7) Emar, (site 9) Hirbet ez-Zeraqon, (site 11) Kamid el-Loz, (site 12) Kinet Höyük, (site 13) Mashnaqa, (site 14) Mezraa Teleilat Höyük, (site 16) Qubur al-Walayida, (site 17) Tell Shioukh Faouqani, (site 18) Shir, (site 19) Tell esh-Shuna, (site 20) Tell Atchana, (site 21) Tell Atij, (site 22) Tell Beydar III, (site 23) Tell Fadous, (site 24) Tell Halaf, (site 25) Tell Kerma, (site 26) Tell Kuran, (site 27) Tell Raqa''i, (site 28) Tell Tawila, (site 29) Tell Tweini, (site 31) Umm Qseir, (site 33) Tell ''el Abd, (site 34) Qatna, (site 35) Tell Mozan, (site 36) Ziyade, (site 37) Chagar Bazar, (site 38) Zebdani (GPS_152), (site 39) GPS_17, (site 42) Tell Snan (GPS_437), (site 43) Summakiak (GPS_50), (site 44) Membij (GPS_629), (site 45) Tell Abyad (GPS_755), (site 46) Tell Brak (GPS_828), (site 48) Malhat ed Deru, (site 51) Tell Bderi, (site 52) Tell Leilan, and (site 53) Tel Burna. Please note that some of the archaeological sites have been sampled only for modern control δ¹³C. For details on the sites and samples, see Table S1.Our working hypothesis is that, even with the limitations in the scope of this study (i.e., we do not consider sociocultural issues that influenced agricultural decision making), large-scale stable carbon isotope analysis of ancient cereal grains contributes to our understanding of how agricultural societies performed under fluctuating climate and regionally diverse environmental conditions.     

Heart rate and heart rate variability as indirect markers of surgeons’ intraoperative stress

Objective

In a difficult and demanding environment such as the operating room, the individual workload response of physicians is of particular importance. The aim of this study was to examine the specific effects of intraoperative stress on the cardiovascular system by measuring heart rate (HR) and heart rate variability (HRV).

Methods

In a cross-sectional study, the effect of intraoperative stress on autonomic balance, measured by HRV, among surgeons differing with respect to their intraoperative stress levels was studied. Based on their perceived stress (State Trait Anxiety Inventory), surgeons were classified into a stressed and a non-stressed sample. Data on HR and HRV were collected by means of ambulatory ECG-recordings. Changes in autonomic nervous system activity were quantified by frequency and time domain analysis of R–R interval variability. Demographic, anthropometric, and surgery-related group differences were assessed by non-parametric Mann–Whitney U test, differences between relative changes of HR and HRV by Wilcoxon signed-ranks test. In multivariate linear analysis of covariance, group differences were adjusted for possible confounding factors.

Results

There was a significant difference in intraoperative HR for stressed and non-stressed surgeons (median: 99.3 vs. 63.7; P < 0.05). During sleep, HRV indices indicated a reduced autonomic recovery in stressed participants.

Conclusions

Our results reveal that higher perceived stress in the operating room is associated with increased intraoperative HR and decreased HRV at night. Non-stressed surgeons show greater relaxation during sleep compared to their stressed colleagues.     

Fasting gastrinemia and elevated supersaturation with hydroxyapatite of fasting urine — Observations in renal calcium stone patients and controls

Summary We evaluated serum gastrin, acid-base status, variables of mineral metabolism in fasting blood, as well as pH, relative supersaturation of stone forming constituents, and crystalluria in the associated fasting urine, of control subjects (n=12), and in age-and weight-matched male normocalciuric (n=12) and hypercalciuric (n=12) patients with idiopathic recurrent calcium urolithiasis (RCU). In RCU, mineral metabolism and acid-base data are unchanged, whereas mean serum gastrin is only insignificantly higher as compared to controls. Subclassification of all participants into categories with either high-normal or low-normal gastrin reveals that in RCU with low-normal gastrin there is a higher-than-normal urinary pH and significantly elevated supersaturation of urine with hydroxyapatite. Crystalluria and stone analysis support the assumption that the physicochemical environment accompanied by low gastrin levels predisposes to urinary precipitation of calcium phosphate with subsequent formation of a stone nidus. pH in fasting urine and integrated fasting serum gastrin correlate significantly, suggesting that low fasting serum gastrin in RCU patients may be considered a rick factor for calcium phosphate stone formation.Abbreviations used in this paper RCU Recurrent calcium urolithiasis - NC Normocalciuria - I-HC Idiopathic hypercalciuria - HAP Hydroxyapatite - cAMP cyclic AMP