New onset of AV-nodal reentrant tachycardia (AVNRT) in the elderly- an uncommon diagnosis?

Funding Acknowledgements

Type of funding sources: None.

Background

Arrhythmias in elderly patients (pat) are common. In this subset of pat, atrial fibrillation is by far the most frequent sustained arrhythmia but not the only one. Clinical, ECG and electrophysiological (EP) features of AV-nodal reentrant tachycardia (AVNRT) have rarely been described in the elderly, and this represents the aim of the current study.

Methods

At 2 EP-centres in Germany, data from all pat undergoing an EP-study (EPS) and diagnosed with AVNRT between January 2018 and May 2021 were collected and analysed. Pat > 65 years constituted the study population.

Results

During the study period AVNRT was diagnosed in a total of 329 pat. 93 pat (28%) were > 65 years and represent the study population [median age 74 (65-89) years, 48% female]. In the majority (85%), the duration of symptoms was short (< 1 year), 14 pat had symptoms of paroxysmal tachycardia for longer than 10 years. Most of the pat (n=88, 94%) had at least one ECG-documentation. In SR, the PR interval was relatively long [median 180 (120-380) ms)]. In 84% of pat, sustained AVNRT [median cycle length (CL) 400 (270-800) ms] was induced during EPS. In the remaining pat, at least 2 typical AV-nodal-echo beats were induced. Slow pathway (SP) ablation/modification was performed in all but one patient presenting with a very long baseline PR-interval, low antegrade Wenckebach-point (WP) and very slow AVNRT. In this case, the pat was treated with ß-blocker after pacemaker (PM) implantation. In 3 additional pat, PM implantation was necessary after ablation due to intermittent high-degree AV-block. In comparison to the rest of the study population, these four pat had a longer baseline PQ interval [median 275 (IQR 248- 303) ms vs. 180 (IQR 160- 192) ms], a longer baseline AH interval [median 207ms (IQR 185- 234) ms vs. 95 (IQR 80- 107) ms], a lower baseline antegrade WP CL [median 510 (IQR 435- 645) vs. 390ms (IQR 355- 470) ms], and a longer tachycardia CL [TCL 557 (IQR 454- 661) ms vs. 400 (IQR 364- 443) ms; p value <0,01 for all comparisons]. The overall complication rate (other than AV block) was low (2 pat with AV fistula treated conservatively) and comparable to the one described in younger pat.

Discussion

Elderly pat also have AVNRT, there are a slight differences in physiology (i.e. relatively long baseline PR-interval and TCL, likely due to changes of the conduction system with aging), and as in young pat, ablation is curative treatment with similar (low) complication rate. A subset of pat, characterized by longer PR- and AH-intervals, lower WP and longer TCL may be at higher risk for AV-block after SP modification. Whether this is due to pre-existing damage or to posterior location of the FP remains unknown.

SP ablation is safe and effective even in elderly pat. In pat presenting with EP characteristics presumptive of a baseline impairment of the conduction properties of the FP, ablation of the FP could be attempted to avoid postprocedural high degree AV block.

New Onset of AV- Nodal Reentrant Tachycardia (AVNRT) in the elderly – an uncommon diagnosis?

Background

Arrhythmias in elderly patients (>70 years) are common in daily clinical practice. Most frequently, they are based on atrial fibrillation or other atrial tachycardia with an indication for oral anticoagulation and specific antiarrhythmic medications. The electrographic (ECG) documentation related to symptoms is essential before therapy initiation. In case of suspected AVNRT based on surface ECG, an electrophysiological study (EP) with ablation as curative strategy should be planned.

Methods

We analysed all patients >70 years with AVNRT diagnosed by electrophysiologic (EP) studies between May 2018 and December 2020.

Results

An EP study for suspected AVNRT was performed in 27 patients >70 years. The diagnosis of AVNRT was confirmed in 20 patients (75%). From all EP- studies with the diagnosis of AVNRT (n=93) in this period, 20 patients (22%) were older than 70 years (mean age 77 years with a range of 70–85 years), 12 were women. In most of the patients, the duration of symptoms was short (3 month). Only 4 patients had symptoms of paroxysmal tachycardia longer than 10 years. Except for 2 patients, all patients had at least one ECG- documentation (12- lead- ECG, Holter- ECG, telemetric ECG and/or in the loop recorder). In 12 patients, a 12- lead- ECG- documentation was available, in 5 patients the tachycardia has been registered in the Holter-ECG and in 1 in a loop recorder. In the 12- lead- ECG before ablation in sinus rhythm the PQ interval was with 196 (120- 300) ms in the upper range. In 16/ 20 patients was during the EP- study a sustained AVNRT (CL 410, 314- 538 ms) inducible. In the others, up to 3 typical AV- nodal- echo beats were induced in the EP- study. A slow pathway ablation/ modification was performed in all patients in typical position. In 2 patients, the implantation of a dual- chamber- pacemaker was necessary due to intermittent high- degree AV-nodal-block during the same hospital stay. In both patients, a first degree AV-block with PQ- interval of 250 and 300 ms was pre-existing.

Discussion

Especially for the elderly patients with new onset of clinical symptoms of arrhythmia, clinical anamnesis including an ECG- documentation is required for planning the therapeutic strategy. A borderline long PQ- interval as sign of an age- dependent fibrosis in the AV- node and, therefore, altered conduction properties in the AV node can be a cause of AVNRT in these older patients. In patients with pre-existing long PQ- interval (>250 ms), the risk of pacemaker implantation after successful ablation is higher. In this group of patients, medical therapeutic options are limited and often associated with the need of pacemaker implantation.

Funding Acknowledgement

Type of funding sources: None.

Heart rate and blood lactate responses during the cross-country test of 2-star to 5-star eventing competitions

The objective of this retrospective study was to evaluate the physiological demands of cross-country competitions at different levels. Heart rates (HR) and post exercise blood lactate concentrations (LAC) measured between 2010 and 2019 in response to 1,463 cross-country competitions (437 at 2-star, 703 at 3-star, 313 at 4-star and 10 at 5-star level) in 294 horses were analysed. The effect of competition level, mean velocity, height profile, total distance, number of jumping efforts, climate, age, sex, percentage of Thoroughbred blood and performance level on HR, LAC, HR recovery and LAC disappearance rates was evaluated by Linear Mixed Effects Models. Mean HR and LAC significantly increased from 2-star to 4-star level (P<0.001). Each 30 m/min increase in mean velocity was associated with a 3 beats/min increase in HR (P<0.001) and a 41% increase in LAC (P<0.001) and each 30 m increase in cumulative elevation with a 2 beats/min increase in HR (P<0.001) and a 32% increase in LAC (P<0.001). Each 20 m increase in mean distance per jumping effort was associated with a 1 beat/min decrease in HR (P<0.01) and a 13% decrease in LAC (P<0.001). Compared to Warmbloods, horses with 75% Thoroughbred blood had 4 beats/min lower HRs (P<0.05) and 34% lower LAC values (P<0.001). Each 5 years increase in age was associated with a 4 beats/min decrease in HR (P<0.001, only in mares) and an 11% decrease in LAC (P<0.01). The HRs during the first 3 minutes of recovery were higher at warmer and more humid conditions (P<0.05). The rate of LAC disappearance was higher in horses with higher percentages of Thoroughbred blood (P<0.05).

Correlation of competition performance with heart rate and blood lactate response during interval training sessions in eventing horses

Objective performance monitoring in eventing horses is rare as the implementation of standardised exercise tests is commonly perceived to interfere with the daily training routine. The validity of performance parameters derived from GPS data, heart rate (HR) and post exercise blood lactate concentration (LAC) measured during usual training sessions should therefore be evaluated. Velocity (V), HR and post exercise LAC recorded during 172 interval training sessions in 30 horses were retrospectively analysed. Linear regression of HR, averaged over retrospectively defined speed ranges, was used to calculate the V at HRs of 150 (V150) and 200 (V200) beats/min. A single exponential regression model, fitted to LAC in relation to HR values from the whole group of horses, was used to predict LAC for each horse’s individual HR value and to calculate the difference between measured and predicted LAC (LACdiff). Recovery HRs were derived from bi-exponential regression of HR decrease after exercise. Results were compared between different stages of training in the same horses and between horses categorised as superior (SP) and average performer (AP) according to their competition performance. V150 and V200 significantly increased with progressing training. SP had higher V150 and V200 values, lower LACdiff values and lower HRs after 1 min of recovery (HRR60s) than AP. Competition performance was positively correlated to V150 and V200 but negatively correlated to LACdiff and HRR60s. Regular monitoring of HR and LAC in response to interval training provided valuable indicators of performance. The results of this study may contribute to an increased applicability of routine performance monitoring in eventing horses.

Mitochondrial function and aerobic capacity assessed by high resolution respirometry in Thoroughbred horses

During the initial stages of training of young Thoroughbred horses, low intensity exercise is employed to increase aerobic capacity. High Resolution Respirometry (HRR) allows the determination of aerobic capacities in small samples of permeabilised muscle fibres. The aim of the study was to measure the mitochondrial function by HRR in Thoroughbred horses, to compare these values to Warmblood horses and to evaluate the effect of a 10-weeks training period. The mitochondrial function was measured by HRR using different substrate-uncoupler protocols (SUIT 1 and 2) in muscle microbiopsies from two groups of untrained horses: 17 Warmblood and 8 Thoroughbred and in the group of 8 Thoroughbred horses before and after a 10-week training period. The SUIT1 protocol employed to compare the two groups of horses showed that in Thoroughbred horses, the mean values for oxygen flux expressed as tissue mass-specific respiration were significantly higher for complex I (CI)Glutamate+Malate, CI + complex II, and maximum electron transport capacities (ETSmax) than the mean values measured in Warmblood horses. The SUIT 1 and SUIT 2 protocols revealed large differences among Thoroughbred horses before and after training. The SUIT 2 protocols showed a significant difference for the complex I activity before and after training but only when the oxygen flux was expressed as percentage of ETSmax. This study shows the interest of HRR in equine sport medicine and exercise physiology, but shows that the technique requires further refinement. Indeed significant differences have been shown between the Thoroughbred and the Warmblood horses highlighting the need to have baseline data for each breed. The Thoroughbred horses had globally a high oxidative phosphorylation capacity with an increase of CI activity induced by an aerobic training program.

Relationship between nonadiabaticity and damping in permalloy studied by current induced spin structure transformations

By direct imaging we determine spin structure changes in Permalloy wires and disks due to spin transfer torque as well as the critical current densities for different domain wall types. Periodic domain wall transformations from transverse to vortex walls and vice versa are observed, and the transformation mechanism occurs by vortex core displacement perpendicular to the wire. The results imply that the nonadiabaticity parameter beta does not equal the damping alpha, in agreement with recent theoretical predictions. The vortex core motion perpendicular to the current is further studied in disks revealing that the displacement in opposite directions can be attributed to different polarities of the vortex core.

A hypothesis: autonomic rhythms are reflected in growth lines of teeth in humans and extinct archosaurs

A major determinant of tooth architecture is the arrangement of lines in dentin and in the enamel following the contour of the surface. Since the original description of these lines in the 19th century, they have been attributed to recurring events during tooth development. They have also attracted the attention of dental scientists and anthropologists; however, to date, studies of these structures have been largely theoretical and microscopic. We show here that the statistical properties of the spacing between the lines are similar in teeth from both ancient and modern humans and from extinct archosaurs, reptiles that lived tens or hundreds of millions of years ago-they also resemble heart rate variability of living humans. We propose that the deposition of these recurring structures is controlled by the autonomic nervous system. This control accounts for their regularity and recurrent nature and implies that the lines are an expression of a biologic rhythm which has been conserved throughout evolution. Details of the rhythms give clues to life styles in ancient civilizations and to the physiology of extinct archosaurs.

Markers of coagulation, fibrinolysis and angiogenesis after strenuous short-term exercise (Wingate-test) in male subjects of varying fitness levels

It was the aim of the study to analyse the haemostatic system during a high standardized intensive short-term (30 s) exercise (anaerobic Wingate test). Blood samples were taken from 15 male subjects before (t0 ), and within 2 (t1 ), 9 (t2 ) and 30 min (t3 ) after the test. We found that the partial thromboplastin time was markedly shortened, whereas the prothrombin time increased slightly from t0 to t1 (p < 0.002) and remained elevated (t3, p < 0.046). Factor VIII increased from t0 to t1 (p < 0.001) and remained elevated as well (t3, p < 0.001). Fibrin monomers were approximately 15 times higher immediately post-exercise (t1, p < 0.001) and continued to be elevated (t3, p < 0.004). The tissue plasminogen activator increased by 4 times after exercise (t1, p < 0.001) and remained elevated (t3, p < 0.002). The d-dimers increased from t0 to t1 (p < 0.001) as well and remained elevated (t3, p < 0.005). Thrombopoietin concentrations were unchanged, whereas the vascular endothelial growth factor increased immediately post-exercise (t0 to t1, p < 0.011 resp. at t2 p < 0.019) and returned to the control level at t3 (p < 0.878). In conclusion, it was found that prothrombotic markers and, even more pronounced, those of the fibrinolytic system were increased. The study provides evidence that due to intensive short-term exercise the balance of the haemostatic system is shifted to a higher equilibrium. Theoretically, the data show that in the case of a subject with risk factors such as impaired fibrinolysis, unfavourable conditions cannot be excluded.

Serum matrix metalloproteinase-2 in patients with malignant melanoma

PURPOSE

Matrix metalloproteinases (MMPs) are a family of structurally related zinc-dependent endopeptidases that are able to degrade extracellular matrix components. MMPs play a role in tumor invasion and tumor metastasis. MMP-2 (also known as gelatinase A) is expressed in human melanoma cells.

METHODS

In this study, we measured MMP-2 in 337 serum probes of 166 melanoma patients with a recently developed enzyme immunoassay and compared these data with the tumor stage, presence of metastases, and the levels of S100beta and soluble intracellular adhesion molecule-1 (sICAM-1) in serum.

RESULTS

The mean levels were (189.2 +/- 50.8) ng/ml for MMP-2, (263.2 +/- 74.1) ng/ml for sICAM-1, and (0.424 +/- 1.568) U/ml for S100beta. There was a statistical significant correlation of MMP-2 with sICAM-1 (P=0.05) and Sl00beta (P=0.01). The mean MMP-2 levels (in ng/ml) in patients with metastatic melanoma were 196.4 +/- 54.0 versus 182.6 +/- 46.9 in non-metastasizing melanoma (P=0.037). However, there was no significant difference in MMP-2 levels between the different tumor stages.

CONCLUSION

Determination of MMP-2 serum levels is of limited value as a tumor marker in melanoma, though there are higher levels in the more advanced disease.

Voice stress monitoring in space--possibilities and limits

An overview of experimental investigations into the use of the voice pitch mode (F0 m) as a distance tool for the monitoring of emotional stress reactions is given. Seven experiments are summarized describing the relations between voice reaction and psychological and physical load in laboratory and field applications. The reactivity of F0 m to mental load depends on psychological personality traits. F0 m is less related to physical load. The evaluation of F0 m as voice stress indicator requires an individual calibration. This calibration has to include the assessment of the individual Autonomic Outlet Type (AOT) because the physiological relevance of voice reactions depends on the individual AOT. The calibration is based on statistical reference data which have to be improved in the future. The calibration has to be done under comparable environmental circumstances. A 3-yr application of the method on board Mir station documents the applicability of the procedure.

Serum protein s100beta in patients with malignant melanoma detected by an immunoluminometric assay

S100 protein is well established as a diagnostic tool in malignant melanoma immunohistology. In this study we measured S100beta in serum with a recently developed luminometric immunoassay with a detection limit of 0.02 microg/l. By measuring S-100beta in a group of apparently healthy individuals a mean value of 0.031 +/- 0.026 microg/l was found. In the reference group, serum S100beta was below 0.12 microg/l in all cases. To assess the sensitivity of the assay we investigated serum S-100beta levels in 371 serum samples of 315 patients with histological proven malignant melanoma at different disease stages. Staging was performed according to the German Society of Dermatology classification. Significant differences were observed between the control group and stages IIb (P = 0.01) and IV (P = 0.001). In tumour-bearing patients of stages IIIb and IV, the difference was highly significant (P < 0.0001). S100beta > 0.20 microg/l helps to distinguish between tumour-free and tumour-bearing patients with a specificity of 97.0% and a sensitivity of 64.6%. Our results demonstrate the serum S100beta is of limited value as a melanoma marker. However, it has clinical significance for identifying tumour-positive patients in advanced malignant melanoma stages III and IV.

Regulatory changes at high altitudes in comparison with post-space-flight reactions

This report will compare results of applications of the psychophysiological method "Assessment of Autonomic Outlet Type" (AOT) in space as well as at high altitudes. The aim was to find out whether it is possible to differentiate a subject's reaction to different environments by this method (Johannes et.al. 1995). This assessment as described below was first applied to clinically well defined cohorts and to healthy subjects. By means of cluster analysis it could be demonstrated that different reaction patterns exist. These different patterns were correlated to two groups of normal controls ([I] = non-responder/voice-responder and [II] = heart-responder) and two groups of patients with different clinical diagnoses (rheumatic diseases ([III] = autonomic-responder) and [IV] = hypertensives). Based on these clinical reference data the method provides for each "new" experiment a common classification of the complex regulatory reaction pattern of the autonomic nervous system (ANS) and the Cardiovascular system (CVS) to psychological stressors by means of a discriminant function. Since August 1997 the experiment has been applied to all Russian cosmonauts continuously each month. (Johannes et.al. 1998). At the same time numerous terrestrial experiments have been running parallel for comparison with the results from space. This report will focus on a study at altitudes of 3600 m.

Vascular endothelial growth factor in exercising humans under different environmental conditions

It was the aim of this study to investigate the time course of changes in the serum concentrations of vascular endothelial growth factor (VEGF) during a regular survival training programme combined with food and fluid deprivation and during a high altitude marathon run. We studied soldiers of the Austrian Special Forces performing survival training at sea-level and marathon runners of the Posta Atletica who crossed the border between Chile and Argentina at altitudes up to 4722 m. Baseline data collected before the 1-week of survival training showed that the soldiers had normal VEGF [n = 8, 246.7 (SD 118.5) pg.ml(-1)] serum concentrations which remained unchanged during the course of the study. Before the high altitude marathon the subjects showed normal VEGF serum concentrations [178 (SD 84.5) pg.ml(-1)]. After the run VEGF concentrations were found to be significantly decreased [41.0 (SD 41.6) pg ml(-1), P < 0.01]. It was concluded that prolonged physical stress during normobaric-normoxia did not alter the VEGF concentrations whereas during severe hypobaric-hypoxia decreased VEGF serum concentrations were measured, at least temporarily, after prolonged physical exercise which might have been due to changes in production, release, removal and/or binding of circulating VEGF.

Assessment of arrhythmia under micro-g by mental loading tests

Based on data of former clinical studies (Johannes et al. 1994) the experiment regulation was designed to assess and classify the actual psychophysiological reactivity of the cosmonauts. Beside this scientific main goal of the experiment it was for us of interest to check the data whether the development of arrhythmia can be seen under micro-g conditions when flight related stressful conditions prevail. This report will focus on the ECG analysis of one subject in whom this was actually the case.

Our ancestral physiological phenotype: an adaptation for hypoxia tolerance and for endurance performance?

There are well known mechanistic similarities in human physiology between adaptations for endurance performance and hypoxia tolerance. By using background principles arising from recent studies of the evolution of the diving response in marine mammals, here we analyze human responses to hypobaric hypoxia based on studies with several different low and high altitude human lineages. As in the evolution of the diving response in pinnipeds, we found "conservative" and "adaptable" physiological characters involved in human responses to hypoxia. Because the analysis concerns traits within a single species, conservative characters dominate the picture (they define basic human physiology and largely are independent of environmental parameters). Most notably, we also found evidence for adaptable characters forming the foundations for a fairly unique physiological phenotype-a low capacity version favored under hypobaric hypoxia and a high capacity one favored for endurance performance. Because current evidence implies that the human species arose under conditions that were getting colder, drier, and higher (situations in which these traits would have been advantageous), we hypothesize that this physiology is our "ancestral" condition.

Psychophysiological reactivity under Mir-simulation and real micro-G

A complex psychophysiological test battery (ECG, blood pressure, SCL, finger temperature e.t.c.) was applied on two subjects in space. It could be shown that the subjects react under space conditions differently than on earth. The data received could be classified into four types of regulation. The subjects changed this type of regulation during the flight and returned to their former pattern after the flight.

Fluid regulation during prolonged physical strain with water and food deprivation in healthy, trained men

The aim of this study was to investigate fluidregulating mechanisms, with special regard to the role of plasma proteins in the control of plasma volume (PV), and the role of the superficial tissues as a water storage organ of the body during prolonged physical strain. 29 male subjects (mean age 22.2 +/- 2.8 years) were studied during a 5 day period of survival training with multifactorial strain including restricted water intake (11 H2O.day-1) and food intake (628 kJ.day-1) additionally to physical exercise and sleep deprivation (20 h within 5 days). Under field conditions the heart rate was monitored continuously, and body mass, body composition, thickness of the shell tissues, and blood parameters were measured at (T1), after 72 h (T2), after 120 h (T3) and in the recovery period after 48 h (T4) and 72 h (T5). The estimated energy expenditure was approximately 24,000 kJ.day-1. The mean decrease of body mass was 6.77 kg (9.5%) at T3 (p < 0.001), 0.95 kg (1.3%) at T4 (p < 0.05) and 0.68 kg (0.9%) at T5 (n.s.). A reduction of total body water of 3.8 1 was estimated at T3. Serum creatinine ([Cr]) was raised at T3 by 18.5% (p < 0.0001). No relationship was found between [Cr] and other parameters. The PV decreased by 3.7% (p < 0.0001) at T2, increased by 1.6% (p < 0.0001) at T3 and was not different to baseline at T4 (+0.2%; n.s.). Total protein concentration ([TP]) increased at T2 (11.7%; p < 0.0001) and T3 (2.6%; p < 0.01), and decreased (p < 0.0001) at T4 (8.2%) and T5 (5.7%). Plasma proteins shifted into the intravascular space at T2 and T3 and moved out of the intravascular space at T4 and T5. This gives support to the hypothesis that one of the counterregulatory mechanisms maintaining PV during prolonged exercise is provided by protein shifts from the extravascular into the intravascular space. Our data provide evidence that this mechanism assists PV homeostasis efficiently over a period of 120 h with multifactorial strain, even under conditions with a fluid loss of almost 8% of the total body water.

Erythropoietin under real and simulated microgravity conditions in humans

The aim of this study was to analyze the time course of erythropoietin (EPO) during Earth-bound microgravity simulations such as bed rest, isolation and confinement (IC), head-down tilt (HDT; -6 degrees), and immersion to evaluate which factors could contribute to alterations in EPO under real microgravity conditions during and after short- (< 10 days) and long-term (> 6 mo) spaceflights. During bed rest (24h), no significant changes in EPO could be observed. Subjects confined in a diving chamber facility for 60 days showed a decrease in EPO. In the recovery period a slight increase was observed, but EPO concentrations did not reach the pre-IC control level. In the control period before HDT, subjects showed normal resting values for EPO, but on day 2 of HDT the EPO concentrations were decreased (P < 0.01). Later the EPO levels remained below the control value and were increased after HDT (P < 0.05). After immersion (24 h) increased EPO concentrations could be determined (P < 0.05). During a short-term spaceflight the astronauts showed in-flight (day 4) decreased and unchanged EPO concentrations. During a long-term spaceflight, 24 h after recovery, the cosmonaut showed slightly elevated EPO concentration, which increased markedly during the following days. It is concluded that 1) HDT (-6 degrees) causes a rapid decrease in EPO in humans, 2) IC per se leads to diminished EPO concentrations, 3) EPO regulation in humans during short- and long-term spaceflights might be different, 4) changes in central blood volume, i.e., central venous pressure, seem to be involved in the modulation of EPO production and release under simulated and real microgravity conditions, and 5) the HDT (-6 degrees) Earth-bound simulation reflects mostly the changes in EPO production and release observed under real microgravity conditions in humans.

Shift working in the Chilean Andes (> 3,600 m) and its influence on erythropoietin and the low-pressure system

It was hypothesized that, in shift workers with a history of intermittent hypoxic stress (working 10 days at > 3,600 m, then resting for 4 days at sea level) for > 5 yr, the initial erythropoietin (EPO) response and the changes in central venous pressure (CVP) are different from those in Caucasian lowlanders. We studied the kitchen personnel (n = 11) of a mine (3,600 m) and a group of Caucasian lowlanders (n = 5). Blood samples were taken, and CVP was determined several times before, during, and after a typical shift. At baseline data collection (BDC) before transition, the shift workers had EPO concentrations of 5.2 +/- 2.4 mU/ml, which increased at altitude (P < 0.01) and returned to BDC values on the recovery (day 16). The Caucasians showed the same time course. Serum transferrin receptor concentrations did not change in either group. CVP values were generally higher in the shift workers than in the Caucasians. In conclusion, the hypothesis that the initial EPO response to a hypoxic stimulus is altered in these shift workers has to be refuted. Higher hemoglobin concentrations and/or CVP values in shift workers might be responsible for the rather low EPO concentrations in shift workers at BDC.

Erythropoietin in 29 men during and after prolonged physical stress combined with food and fluid deprivation

The study investigated the influence of prolonged physical stress during survival training with food and fluid deprivation on the serum concentrations of erythropoietin (EPO). A group of 29 male subjects [mean age 22.2 (SD 2.8) years, height 1.78 (SD 0.06) m, and body mass (m(b)) 73.5 (SD 8.6) kg] were studied for 5 days of multifactorial stress including restricted water intake (11 H2O. day(-1)) and food intake (628 kJ. day(-1)) combined with physical exercise (estimated energy expenditure approximately 24000 kJ.day(-1)) and sleep deprivation (20 h within 5 days). Blood samples were taken before (T1), after 72 h (T2) and 120 h (T3) of physical stress, and after 48 h, (T4) and 72 h (T5) of recovery. The samples were analysed for EPO, and concentrations of serum iron (Fe), haptoglobin (Hapto), transferrin (Trans), ferritin (Fer), haemoglobin (Hb) and packed cell volume (PCV). The m(b) had decreased by 6.77 kg at T3 (P <0.01) and 0.68 kg at T5. The EPO and Hapto decreased during the survival training (P <0.01) and increased during the recovery period (P <0.01). The Fe increased during the survival training (P <0.01) and remained above the control concentrations during recovery (P <0.01). The Hapto decreased during the survival training (P <0.01) and remained below control concentration at T4 and T5 (P <0.01). The Trans decreased continuously over the week (P <0.01). The Fer increased during the survival training (P <0.01) and returned to control concentration at T5. The Hb increased from T1 to T2 (P <0.01) and had decreased significantly at T5 (P <0.01). The PCV increased from T1 to T2 (P <0.01) and remained below control levels afterwards (P <0.01). From our study it was concluded that, in humans, prolonged physical stress with food and fluid deprivation induces a marked EPO decrease, which is followed by a rapid increase during recovery to restore the reduced O2 transport capacity.

Unconventional cancer therapy--survey of patients with gynaecological malignancy

Although the benefits remain unproven, a considerable number of cancer patients use unconventional therapy, in many cases without the knowledge of the oncologist. At the oncological out-patient department of the women's clinic of the Justus-Liebig-University Giessen we conducted a survey of the various unconventional methods used. 38.8% (80/206) of the patients used unconventional therapies, mainly mistletoe extracts (50%), trace minerals (46%), megavitamins (39%), and enzymes (22%). The perceived etiology of cancer determined the choice for the various methods (p = 0.00074). Users of unconventional methods suffered significantly more from conventional therapy, had less faith in their doctors, and felt more nervous and emotionally unstable after the diagnosis of "cancer".

Blood volume regulating hormones response during two space related simulation protocols: four-week confinement and head-down bed-rest

The volume of regulating hormones (renin, aldosterone, arginine vasopressin and atrial natriuretic factor), electrolytes and creatinine concentrations, and blood pressure were measured in two different four-week experimental protocols: respectively -6 degrees head-down bed-rest (5 subjects) and confinement (6 subjects). We observed a significant increase (P < 0.01 at D2 vs D-5) of systolic blood pressure during confinement and a different level of response for some hormones, especially for arginine vasopressin (300% increase during confinement instead of 50% during bed-rest). The renin-angiotensin-aldosterone system was enhanced during confinement and head-down bed-rest. In both conditions, we obtained a similar pattern of response for blood volume regulating hormones. During confinement, two main factors were inactivity and stress activation of the sympathetic nervous system. In the bed-rest study the response is principally due to the fluid shift and blood volume adaptation but it is not possible to exclude the role of inactivity and stress.

Fluid distribution and tissue thickness changes in 29 men during 1 week at moderate altitude (2,315 m)

To quantify fluid distribution at a moderate altitude (2,315 m) 29 male subjects were studied with respect to tissue thickness changes [front (forehead), sternum, tibia], changes of total body water, changes of plasma volume, total protein concentrations (TPC), colloid osmotic pressure (COP), and electrolytes. Tissue thickness at the forehead showed a significant increase from 4.14 mm to 4.41 mm 48 h after ascent to the Rudolfshuette (2,315 m) (P < 0.05). At 96 h after ascent the tissue thickness at the tibia was decreased to 1.33 mm compared to the control value of 1.59 mm (P < 0.01). Body mass increased from 75.5 kg (control) to 76.2 kg on the last day (P < 0.05) and body water from 44.21 to 45.01 during the week (P < 0.01). The accumulation fluid in the upper part of the body was paralleled by a decrease in TPC and COP. At 48 h after the ascent COP dropped from 29.5 mmHg to 27.5 mmHg (P < 0.01). After 96 h at moderate altitude COP was still significantly decreased compared to the control level. At 1.5 h after the return from the Rudolf-shuette in Saalfelden (744 m) COP was back to the control values. The TPC also showed an initial drop from 7.75 g.dl-1 to 7.48 g.dl-1 after 48 h at altitude and remained below the control value during the whole week (P < 0.01). It seems from our study that even with exposure to moderate altitude measurable fluid shifts to the upper part of the body occurred which were detected by our ultrasound method.

Time course of erythropoietin, triiodothyronine, thyroxine, and thyroid-stimulating hormone at 2,315 m

Erythropoietin (EPO), triiodothyronine, thyroxine, thyroid-stimulating hormone (TSH), hemoglobin (Hb), reticulocytes, packed cell volume, and plasma volume changes were studied in 29 male Austrian mountain rescue soldiers before and several days after an ascent from 744 to 2,315 m in the Alps. EPO concentrations showed a remarkable increase 48 h after the ascent (P < 0.01). No significant changes were found in triiodothyronine, thyroxine, and TSH. Reticulocytes increased only slightly. Hb decreased during the week (P < 0.01). Packed cell volume did not change, whereas plasma volume showed a slight decrease for 48 h after the ascent but then increased constantly (P < 0.01). It seems that thyroid hormones, TSH, and Hb play only a minor role in the regulation of EPO production and release under mild hypobaric-hypoxic conditions (2,315 m).

Enhanced slow caudad fluid shifts in orthostatic intolerance after 24-h bed-rest

To evaluate mechanisms of late orthostatic intolerance, slow fluid shifts along the body axis were studied during deconditioning by 24-h bed-rest and during 13-min upright tilts before and after this manoeuvre. In 11 healthy male subjects the fluid volumes of a thorax and a calf segment (impedance plethysmography) as well as tissue thickness at the forehead and the tibia (miniature ultrasonic plethysmograph) were recorded. Cardiovascular performance was monitored by recording heart rate (electrocardiogram), brachial and finger arterial pressure (by the Riva Rocci method and by the Finapres technique) as well as stroke volume (by impedance cardiography). Bed-rest led to a cephalad fluid shift with a mean interstitial leg dehydration of 2.2 ml.100 ml-1 with no changes in body mass and plasma volume. No syncope during the tilt occurred before bed-rest, while after bed-rest 8 subjects fainted between min 2.1 and 9.0 of the tilt. Bed-rest resulted in an augmented initial heart rate response to tilting which was similar in all subjects. In later orthostasis, bed-rest caused two- to threefold faster caudad fluid shifts with higher calf filtration rates in fainters (prior to hypotension) than in nonfainters. Through bed-rest the estimated extravasation within 10 min into general lower body tissue spaces increased by 192 ml in (late) fainters as opposed to only 23 ml in nonfainters. It was concluded that contributing factors to orthostatic intolerance may be slow transcapillary fluid shifts which are easily underestimated and whose quantity and time course call for further investigation after various deconditioning manoeuvres. In particular, the postflight fluid shifts in astronauts who will have markedly dehydrated legs, may impose a circulatory stress which needs to be evaluated. In general, the filtration rate in relevant areas appears to be an integrative and easily determined parameter, reflecting hormonal and neurogenic vascular as well as local interstitial control of the Starling forces.

Genomic organization of the melanoma-associated glycoprotein MUC18: implications for the evolution of the immunoglobulin domains

The cell surface glycoprotein MUC18, a member of the immunoglobulin superfamily and homologous to several cell adhesion molecules, is associated with tumor progression and the development of metastasis in human malignant melanoma. Immunohistochemical and Northern blot analysis revealed that expression of the antigen is restricted to advanced primary and metastatic melanomas and to cell lines of the neuroectodermal lineage. The genomic sequence encoding the cell surface antigen spans approximately 14 kb and consists of 16 exons. The organization of the gene, which is related to that of the neural cell adhesion molecule N-CAM, shows a structure where each immunoglobulin-related domain is encoded by more than one exon. Sequencing of the putative MUC18 promoter region revealed a G + C-rich promoter lacking conventional TATA and CAAT boxes. Several motifs for binding of transcription factor Sp1 are present in the regulatory region, and only a single transcription start site within a presumed initiator sequence was identified. Sequence elements which might confer melanocyte-specific expression were not detected. Instead, recognition sequences for the transcription factors CREB, AP-2, and c-Myb, as well as CArG-box motifs, were observed. These elements may contribute to the differential regulation of the MUC18 gene in normal and malignant tissues and suggest a role for this putative adhesion molecule in neural crest cells during embryonic development.

Effects of 28-day isolation (ESA-ISEMSI'90) on blood pressure and blood volume regulating hormones

The aim of this study was to determine what effects social isolation and confinement stress had on the volume regulating hormones. In six healthy male subjects, during a 28-d isolation and confinement study (ESA-ISEMSI'90), hematocrit, blood pressure and resting heart rate, plasma cortisol, renin, aldosterone, arginine vasopressin levels besides the electrolyte (Na+, K+) balance and plasma creatinine were measured. During the confinement, an elevated systolic blood pressure (p < 0.01) was observed together with an increase in MHPG corresponding to an elevated mental work load. The pattern displayed by volume regulating hormones (increased values for renin, aldosterone (p < 0.05) and arginine vasopressin) was not only characteristic of confinement stress but also reflected changes in the water and electrolyte metabolism. The increased creatinine levels seen throughout the study were regarded as consequences of hypohydration, and an enhanced muscular catabolism due to reduced physical activity. A similar pattern of hormone modifications was obtained in a head down tilt of the same duration, indicating that some of the described modifications are probably related to isolation and confinement stress.

European isolation and confinement study. Water and salt turnover

Intake and output of water were studied in six male subjects from six European countries during 28 days of isolation and confinement in order to assess whether the observed reactions can be compared with those observed during space travel. On the average, the subjects drank 17.5 ml/kg/day fluids. An additional 25 ml/kg/day was recruited from food intake and metabolism. The lowest fluid intake of 11.3 and 12.1 ml/kg/day was shown by two subjects who concurrently lost 3 to 4% of body weight. Three subjects maintained body weight, and one subject gained. A linear correlation existed between the total water output and the fluid intake by drinking. The time series of fluid intake, urine output, and sodium excretion revealed a weekly pattern for these parameters, characterized by low values on Sundays and high values on Fridays. This pattern was most apparent for sodium excretion. Low water turnover rates were seen in the first week of isolation; in the last week the values were above average. In conclusion, it can be said that with respect to the water balance, strong individual differences and time dependent variations (day to day, week to week) of the respective parameters have to be taken into account for the data analysis during such long-term studies.

Beta 2-microglobulin gene is mutated in a human colon cancer cell line (HCT) deficient in the expression of HLA class I antigens on the cell surface

The human colon cancer cell line HCT does not express any detectable HLA class I antigens on the cell surface. RNA blot analyses showed that HCT cells synthesize easily detectable levels of heavy chains as well as beta 2-microglobulin (beta 2m) transcripts. Experiments of immunoprecipitation revealed the presence of intracellular HLA heavy chains and the absence of beta 2m molecules. Sequencing studies, performed on polymerase chain reaction-mediated amplification of beta 2m-specific complementary DNAs, indicated that in HCT cells both beta 2m genes are mutated. The first mutation consists of an 11-base deletion, corresponding to the first 11 base pairs of the second exon of the beta 2m gene. This mutation alters the reading frame, starting from the third amino acid residue of the mature beta 2m protein, resulting in the synthesis of a 31-amino acid peptide with no remarkable homology to any of the sequences stored in the protein database. The second mutation is a point mutation (C----A), resulting in a UAA stop codon corresponding to the 10th amino acid residue of the mature beta 2m. Therefore, it would appear that in HCT cells the beta 2m genes have undergone two different mutational changes. This is the first molecular demonstration of beta 2m mutations in a human epithelial cell line.

Partial suppression of anchorage-independent growth and tumorigenicity in immunodeficient mice by transfection of the H-2 class I gene H-2Ld into a human colon cancer cell line (HCT)

Many human tumors, particularly those of epithelial origin, appear to express greatly reduced levels of major histocompatibility complex class I antigens on their surface. It has been previously reported that the class I gene H-2Ld, introduced into adenovirus type 12-transformed mouse cells, induces reversal of oncogenesis in immunocompetent BALB/c mice. We have tested the hypothesis that the H-2Ld gene, when transfected into HCT colon cancer cells, may alter their transformed phenotype. Two H-2Ld transfectants, HCT-Ii and HCT-If, were found to exhibit a markedly reduced-to-virtually suppressed ability to form colonies in soft agar in comparison to a transfectant (HCTh) carrying only the neomycin-resistance gene. We also compared the tumorigenicity of HCTh vs. HCT-If cells in two different strains of immunodeficient mice: nude (T-) and triple-deficient mutants (T-, NK-, B-). At 28 days postinjection of 10(7) and 10(6) cells, the size and growth rate of HCT-If tumors were greatly reduced compared to HCTh cells. Therefore, as assayed in immunodeficient animals, expression of the class I H-2Ld gene in HCT cells appears to correlate with partial suppression of the tumorigenic phenotype, suggesting that the expression of a transfected class I gene may by itself alter the phenotype of the recipient cell and that such phenotypic changes may be independent of the immune system.

Islet cell antigens. Extraction studies and ELISA analysis

Whole human and bovine pancreases were extracted in 20 mM Tris-HCl buffer without detergents and fractionated by high-speed centrifugation. The 80,000 x g supernatant was used to coat microtiter plates at a concentration of 5 micrograms protein/ml in phosphate-buffered saline. This solid-phase ELISA system was used for the detection of islet cell antigens defined by a series of monoclonal islet cell antibodies (HISL-1, -4, -5, -8, -14, and -19 and 4F2, 3G5, and A2B5). Both glycoprotein and glycolipid islet cell antigens in the total pancreatic extracts were detected by the monoclonal islet cell antibody in the ELISA system, indicating that epitope preservation had occurred during the extraction procedure. There was a good correlation between islet cell antigen quantitated by the ELISA system and the corresponding islet immunohistochemical reaction. Studies along these lines have the potential to facilitate the design of large-scale protocols for the purification of diabetes-related islet cell antigens to homogeneity.

Herbicide tolerant regenerates of potato

Culture-derived plants and cell cultures of potato (Solanum tuberosum L.) respond to the application of the herbicides SYS 67 ME (MCPA) and OMNIDEL (Na-2,2-dichloropropionate) in a comparable fashion. By gradually increasing the herbicide concentration, cell lines were developed which tolerated 50 mg/l of ME or 300 mg/l of OMNIDEL. Any further increase in concentration resulted in the death of all cell cultures. From cell cultures that had been able to grow on media supplemented with 30 mg/l of ME, regenerate plants were obtained that were also tolerant to this concentration. This new trait was retained even after repeated vegetative propagation of the plants.

Correlation of HBV DNA and monoclonal reactivity to HBsAg in serum of patients with HBV infection

Hepatitis B virus (HBV) DNA hybridization assay, a monoclonal radioimmunoassay (M-RIA) for hepatitis B surface antigen (HBsAg) and conventional polyclonal immunoassays for HBV associated antigens were used to study sera from patients on dialysis and with acute hepatitis B. HBV DNA was detectable in hepatitis B e antigen (HBeAg) negative patients with acute hepatitis but not in HBsAg+ HBeAg- dialysis patients. In acute hepatitis, HBsAg immunoreactivity by M-RIA could still be detected even though a commercial immunoassay for HBsAg, the AUSRIA II, and the HBV DNA assay were no longer positive. Unlike in acute HBV infection, serum HBV DNA was detectable in dialysis patients who were AUSTRIA II negative but M-RIA positive. Serial determination of HBsAg by M-RIA and HBV DNA revealed episodes of HBV DNA positivity months after both the HBsAg was no longer positive by polyclonal immunoassay. Thus, the M-RIA for HBsAg and the molecular hybridization technique for HBV DNA are sensitive and specific assays for the identification of potentially infectious individuals who would not have been characterized as such based on the results of conventional polyclonal immunoassays.

Expression of type C-related endogenous retroviral sequences in human colon tumors and colon cancer cell lines

Type C-related human endogenous retroviral sequences have been previously discovered and characterized [Martin, M. A., Bryan, T., Rasheed, S. & Khan, A.S. (1981) Proc. Natl. Acad. Sci. USA 78, 4892-4896]. We investigated the transcriptional pattern of these sequences to determine whether and to what extent their expression is altered in colon tumors and colon cancer cell lines as compared to normal colon mucosa (NCM). Of two long terminal repeat (LTR)-specific transcripts [3.6 and 2.1 kilobases (kb)], the 3.6-kb RNA was particularly abundant in NCM but strikingly decreased in most primary colon cancers tested. In NCM we identified three envelope gene (env)-related transcripts--namely, 3.0, 1.7, and 0.6 kb. Colon tumors appeared to express higher levels of these transcripts, especially the 1.7-kb species. In one case of dysplasia and in one benign tumor, this 1.7-kb transcript was clearly increased. We also examined the pattern of transcription in colon cancer cell lines HCT and Caco2. The LTR-homologous 3.6-kb transcript, very abundant in NCM, was decreased in primary tumors and in HCT cells and virtually absent in Caco2 cells. The latter, however, appeared to produce the transcript when growing exponentially, indicating that Caco2 cultures provide an inducible system susceptible to in vitro manipulation. Both cell lines also contained higher amounts of the 1.7-kb env-related transcript. The decrease of the 3.6-kb RNA in colon tumors versus NCM may be the result of an altered pattern of differentiation, whereas the increase of the 1.7-kb RNA in tumors may represent an early marker of colon neoplasia.