Oral magnesium therapy, exercise heart rate, exercise tolerance, and myocardial function in coronary artery disease patients

BACKGROUND

Previous studies have demonstrated that in patients with coronary artery disease (CAD) upward deflection of the heart rate (HR) performance curve can be observed and that this upward deflection and the degree of the deflection are correlated with a diminished stress dependent left ventricular function. Magnesium supplementation improves endothelial function, exercise tolerance, and exercise induced chest pain in patients with CAD.

PURPOSE

We studied the effects of oral magnesium therapy on exercise dependent HR as related to exercise tolerance and resting myocardial function in patients with CAD.

METHODS

In a double blind controlled trial, 53 male patients with stable CAD were randomised to either oral magnesium 15 mmol twice daily (n = 28, age 61+/-9 years, height 171+/-7 cm, body weight 79+/-10 kg, previous myocardial infarction, n = 7) or placebo (n = 25, age 58+/-10 years, height 172+/-6 cm, body weight 79+/-10 kg, previous myocardial infarction, n = 6) for 6 months. Maximal oxygen uptake (VO2max), the degree and direction of the deflection of the HR performance curve described as factor k<0 (upward deflection), and the left ventricular ejection fraction (LVEF) were the outcomes measured.

RESULTS

Magnesium therapy for 6 months significantly increased intracellular magnesium levels (32.7+/-2.5 v 35.6+/-2.1 mEq/l, p<0.001) compared to placebo (33.1+/-3.1.9 v 33.8+/-2.0 mEq/l, NS), VO2max (28.3+/-6.2 v 30.6+/-7.1 ml/kg/min, p<0.001; 29.3+/-5.4 v 29.6+/-5.2 ml/kg/min, NS), factor k (-0.298+/-0.242 v -0.208+/-0.260, p<0.05; -0.269+/-0.336 v -0.272+/-0.335, NS), and LVEF (58+/-11 v 67+/-10%, p<0.001; 55+/-11 v 54+/-12%, NS).

CONCLUSION

The present study supports the intake of oral magnesium and its favourable effects on exercise tolerance and left ventricular function during rest and exercise in stable CAD patients.

Intravenous mirtazapine is safe and effective in the treatment of depressed inpatients

Mirtazapine is a third-generation antidepressant with a dual mode of action. The oral administration has been shown to be effective and safe in the treatment of depressed patients. In this multicenter naturalistic study, we assessed the safety, tolerability, and therapeutic efficacy of intravenously administered mirtazapine in 80 moderately to severely depressed inpatients during a treatment period of 14 days. We found a significant decrease of the Hamilton Depression Rating Scale total score compared to baseline. Side effects were mild and transient. Our data indicate that intravenous mirtazapine is an effective, safe and well-tolerated treatment for depressed inpatients.

Novel shielding materials for space and air travel

The reduction of dose onboard spacecraft and aircraft by appropriate shielding measures plays an essential role in the future development of space exploration and air travel. The design of novel shielding strategies and materials may involve hydrogenous composites, as it is well known that liquid hydrogen is most effective in attenuating charged particle radiation. As precursor for a later flight experiment, the shielding properties of newly developed hydrogen-rich polymers and rare earth-doped high-density rubber were tested in various ground-based neutron and heavy ion fields and compared with aluminium and polyethylene as reference materials. Absorbed dose, average linear energy transfer and gamma-equivalent neutron absorbed dose were determined by means of LiF:Mg,Ti thermoluminescence dosemeters and CR-39 plastic nuclear track detectors. First results for samples of equal aerial density indicate that selected hydrogen-rich plastics and rare-earth-doped rubber may be more effective in attenuating cosmic rays by up to 10% compared with conventional aluminium shielding. The appropriate adaptation of shielding thicknesses may thus allow reducing the biologically relevant dose. Owing to the lower density of the plastic composites, mass savings shall result in a significant reduction of launch costs. The experiment was flown as part of the European Space Agency's Biopan-5 mission in May 2005.

[Personality profile and psychic deviations in offenders examined for psychiatric-forensic appraisal]

Personality is one factor within the multidimensional structure of conditions involved in the development of an offender. The aim of this study is to contribute to a better accuracy of discrimination of risk factors and prediction of delinquent behaviour. For psychiatric-forensic opinions, social, forensic and psychiatric history as well as type of the last offence and its course for adjudged delinquents (n=128) was recorded. For determining personality structure, the "Freiburger Personlichkeitsinventar" (FPI-R) and the "Fragebogen zur Erfassung von Aggressivitatsfaktoren" (FAF) was used. Psychiatric diagnosis was based on criteria of ICD-10. Using a hierarchical cluster analysis including the dimensions of the FPI-R, three personality profiles could be separated. First offenders and re-offenders could be discriminated by family environment and age at the first delict. The importance of classification for risk estimation of delinquent behaviour and its significance for providing forensic opinions is discussed.

Sexuality in multiple sclerosis

Sexuality and partnership have an important influence on the quality of life of every person and also on people with chronic disorders such as multiple sclerosis. The findings in literature show high evidence that people with multiple sclerosis experience high levels of sexual dysfunction, most of them with hypoactive sexual behaviour often associated with dissatisfaction in relationship, and also the partners seem to show lower sexual and partnership satisfaction. The most common problems in women are lack of sexual interest and decreased libido, often with problems in orgasmic capacity, while men report erectile dysfunction and also lack of sexual interest. The impact of the level of disability and duration of the illness remains unclear. Positive familial support can often help the patient in coping with the illness, nonetheless problems with changing roles and multiple-sclerosis-minimizing can improve the need of contacts to outstanding persons.

Role of spin in quasiparticle interference

Quasiparticle interference patterns measured by scanning tunneling microscopy can be used to study the local electronic structure of metal surfaces and high-temperature superconductors. Here, we show that even in nonmagnetic systems the spin of the quasiparticles can have a profound effect on the interference patterns. On Bi(110), where the surface state bands are not spin degenerate, the patterns are not related to the dispersion of the electronic states in a simple way. In fact, the features which are expected for the spin-independent situation are absent and the observed interference patterns can be interpreted only by taking spin-conserving scattering events into account.

Strong spin-orbit splitting on bi surfaces

Using first-principles calculations and angle-resolved photoemission, we show that the spin-orbit interaction leads to a strong splitting of the surface-state bands on low-index surfaces of Bi. The dispersion of the states and the corresponding Fermi surfaces are profoundly modified in the whole surface Brillouin zone. We discuss the implications of these findings with respect to a proposed surface charge density wave on Bi(111) as well as to the surface screening, surface spin-density waves, electron (hole) dynamics in surface states, and to possible applications to the spintronics.

Strong energy dependence of the electron-phonon coupling strength on Bi(100)

We have studied the energy dependence of the electron-phonon coupling strength on Bi(100). A fit of the temperature-dependent surface state linewidth results in a change of the coupling parameter lambda from 0.20+/-0.02 to 0.72+/-0.05 as the binding energy of the surface state increases from 70 to 330 meV. This result cannot be reconciled with the usual interpretation of lambda as the electron-phonon mass enhancement parameter at the Fermi energy. We suggest that this behavior is mainly caused by the strong energy dependence of the bulk density of states in this region.

[Electron microscopic investigation of CD4+ lymphocyte cell line C8166 after infection with simian immunodeficiency virus (SIV)]

The SIV infection of rhesus macaques (Macaca mulatta) is the most appropriate animal model in HIV research. The permanent human T-cell line C8166 is used for in vitro SIV propagation. This paper describes ultrastructural features of the cells after infection with SIVmac. The C8166 cells are ultrastructurally characterized by a heterogenous morphology which is independent of the infection. SIV induced cell syncytia are observed 18 hours after infection. Viral particles and budding occur 48 hours p.i with a peak at the day 8. Viral particles present the typical lentiviral morphology. Using the monoclonal antibody anti SIVp28 and ultra small (0.8 nm) immunogold-silver enhancement technique, we are able to demonstrate SIV antigen immunoelectron microscopically. Therefore, this ultrastructural method is suitable to detect SIV antigen in in vivo experiments with C8166 cells from day 8 p.i. serving as positive control.

Validation of a field test for the non-invasive determination of badminton specific aerobic performance

AIM

To develop a badminton specific test to determine on court aerobic and anaerobic performance.

METHOD

The test was evaluated by using a lactate steady state test. Seventeen male competitive badminton players (mean (SD) age 26 (8) years, weight 74 (10) kg, height 179 (7) cm) performed an incremental field test on the badminton court to assess the heart rate turn point (HRTP) and the individual physical working capacity (PWC(i)) at 90% of measured maximal heart rate (HR(max)). All subjects performed a 20 minute steady state test at a workload just below the PWC(i).

RESULTS

Significant correlations (p<0.05) for Pearson's product moment coefficient were found between the two methods for HR (r = 0.78) and velocity (r = 0.93). The HR at the PWC(i) (176 (5.5) beats/min) was significantly lower than the HRTP (179 (5.5) beats/min), but no significant difference was found for velocity (1.44 (0.3) m/s, 1.38 (0.4) m/s). The constant exercise test showed steady state conditions for both HR (175 (9) beats/min) and blood lactate concentration (3.1 (1.2) mmol/l).

CONCLUSION

The data indicate that a valid determination of specific aerobic and anaerobic exercise performance for the sport of badminton is possible without HRTP determination.

Post-exercise decrease of plasma hyaluronan: increased clearance or diminished production?

The exercise-induced increase and post-exercise decrease of plasma hyaluronan concentration were studied in human subjects. Six well trained men performed incremental exercise until exhaustion (MAX), intensive (submaximal, SUB) and extensive exercise (moderate, MOD) on a bicycle ergometer, defined as work at 100, 77 and 50% of maximal oxygen consumption. Hyaluronan was analyzed using a high-sensitivity, proteoglycan-dependent time-resolved immunoassay and hemoglobin, hematocrit and plasma protein levels were assessed using standard laboratory procedures. Compared to resting control levels, the plasma hyaluronan concentration (pHA) increased (p < 0.05) by 76% (65.0 +/- 6.1 vs. 37.0 +/- 1.0 microg/l) during 15 min MAX, by 44% (56.4 +/- 2.6 vs. 39.2 +/- 3.8 microg/l) during 30 min SUB and by 27% (46.3 +/- 7.8 vs. 36.4 +/- 4.3 microg/l) during 90 min MOD. The increase with time averaged 4.03%.min(-1) during MAX, 1.35%.min(-1) during SUB and 0.35%.min during MOD. After exercise (15 and 30 min), pHA decreased by 43% below resting levels after MAX (p < 0.05) and by 36% after SUB, respectively. In conclusion, pHA steadily rose with time during physical exertion, with a non-linear increase of concentration/time slope with exercise intensity; second, the magnitude of the post-exercise pHA decrease was proportional to the exercise-induced pHA increase, suggesting elevated hyaluronan clearance with rising plasma levels after physical exertion.

Long-term follow-up after osteotomy for haemophilic arthropathy of the knee

In this study the long-term value of corrective osteotomy around the knee was evaluated by means of clinical and radiographic parameters. Between 1974 and 1984 we performed 52 corrective osteotomies in the vicinity of the knee on patients affected by haemophilic arthropathy. Forty-two patients (45 osteotomies) were adequately followed-up at an average 11.6 years postoperatively. Using the clinical score of the Advisory Committee of the World Federation of Haemophilia, 38 patients showed a postoperative improvement, five remained clinically unchanged and two showed deterioration. Range of motion of the knee joint did not significantly improve postoperatively. The radiographic Pettersson score showed only a marginal decrease by an average 0.003 points at the time of follow-up. Only one patient needed subsequent joint replacement of both knees, on the left side 13 years after osteotomy and on the right side 8 years after osteotomy. Even in cases of marked radiographic joint destruction, corrective osteotomy shows acceptable long-term clinical results, underlining the feasibility of this management option in the treatment of haemophilic arthropathy of the knee. Although moderate cartilage degenerations in the femoropatellar complex and in the contralateral compartment can be tolerated, this therapy should primarily be contemplated for those patients where damage is unicompartmental and a corresponding axial deviation is found. Particularly the younger patient can benefit from this treatment option in that joint replacement may possibly wholly be avoided or at least postponed to a later stage of life.

Long-term follow-up after intertrochanteric varus osteotomy for haemophilic arthropathy of the hip

In view of an increasing tendency in prosthetic management of haemophilic arthropathy, we intended to evaluate the efficacy of corrective osteotomy of the hip, specifically taking long-term clinical and radiographic results into consideration. Eleven hips affected by haemarthropathy in nine patients suffering from severe haemophilia A were treated with an intertrochanteric varus osteotomy. The average follow-up period was 15 small middle dot4 years. The preoperative clinical score of the Advisory Committee of the World Federation of Haemophilia was 5 small middle dot3 points (range 4-7) and the Pettersson score was 6 small middle dot4 points (range 2-10). The average WFH score at follow-up had increased to 3 small middle dot6 points. Seven hips showed clinical improvement, two hips showed a postoperative deterioration while a further two hips remained unchanged. The Petterson score increased to an average of 7 small middle dot7 points. Here the radiographs of six patients indicated postoperative deterioration, three remained unaltered and two showed improvement. Our study cannot conclusively answer whether intertrochanteric varus osteotomy for haemophilic arthropathy of the hip is always a feasible alternative to joint arthroplasty. The decision for or against this procedure must be individually assessed and the patient must be thoroughly informed about the advantages and disadvantages of both procedures.

[understanding and radiation hygiene assessment of solar UV exposure in Germany]

In order to monitor the natural ultraviolet (UV) radiation and to assess it from the point of view of radiation hygiene, the Federal Office for Radiation Protection (BfS) and the Federal Environmental Agency (UBA) have built up a common network for UV monitoring. Since 1993, the ground-level solar UV radiation has been measured at four sites in Germany every 6 minutes, with spectroradiometers in the wavelength range between 290 and 400 nm. Because erythema (sunborn) is of special interest in terms of radiation hygiene, the erythemal weighted irradiance was used as a measure for the biological effect of UV exposure. For this purpose, the measured spectral irradiance was multiplied by the relative erythemal weighting function, and the resulting function integrated from 290 to 400 nm. In the summer months of June and July 1999, the erythemal irradiance exceeded regularly the value of 175 mW/m2 in the south of Germany. In the north, values of not less than 160 mW/m2 were measured during this period. These values correspond to an UV index of more than 7 or 6, respectively--a high exposure regarding to the classification of the German Radiation Protection Commission (SSK), for which (absolute) sun protection is recommend. Between 1995 and 1999, the four sites were characterized by a small increase of the ground-level UV exposure of approx. 10%. Nevertheless, in consideration of the manifold factors affecting the acquired data, the measuring period of 5 years is still insufficient to demonstrate an ozone-dependent effect.

SIV-associated lymphomas in rhesus monkeys (Macaca mulatta) in comparison with HIV-associated lymphomas

A retrospective study was performed to characterize malignant lymphomas of 16 Simian immunodeficiency virus (SIV)-infected rhesus monkeys (Macaca mulatta), 2-9 years of age, on the basis of clinical data, histologic and immunophenotypic results, and cell death indices compiled with the TdT-mediated X-duTP nick end labeling method. We particularly focused on providing immunohistochemical evidence of expression products of EBNA2, Bc12, c-Myc, P21, P53, and Bc16. Results were compared with data from the literature on human HIV-associated lymphomas. According to the updated Kiel classification, the lymphomas were classified as 11 centroblastic lymphomas, three immunoblastic lymphomas, one Burkitt-like lymphoma, and one immunocytoma. Using antibodies to CD20, the B-cell origin of tumor cells was demonstrated. SIV antigen was not demonstrated in the tumor cells. Infection with rhesus lymphocryptovirus was present in 94% of the monkeys. Lymphomas revealed expression of Bc12 in 15/16 (94%), c-Myc in 14/16 (88%), P21 in 10/ 16 (63%), P53 in 12/16 (75%), and Bc16 in 1/16 (6%) monkeys. This study provided evidence that the expression of these gene products, which are thought to play an important role in cell proliferation and apoptosis in HIV- and non-HIV-associated lymphomas, are also involved in the pathogenesis of lymphomas in SIV-infected rhesus monkeys. A tentative relationship between the described gene products and the cell death indices was established for the expression of Bc12. The present primate model represents a suitable animal model for studying the pathogenesis of AIDS-associated lymphomas.

Three spontaneous lymphomas in a colony of cotton-top tamarins (Saguinus oedipus)

Cotton-top tamarins are well known for their prevalence to idiopathic colitis and adenocarcinomas. At the same time, information on the incidence of spontaneous lymphomas in this highly endangered species is rare. Records, 212 in total, of cotton-top tamarins (Saguinus oedipus) necropsied at the German Primate Centre between 1979 and 1998 were viewed to establish the prevalence of lymphoid neoplasms. Neoplastic lymphoid cell growth was mentioned in three necropsy records. Immunohistology was performed in all three cases on the remaining formalin-fixed, paraffin-embedded tissue using antibodies against CD20, CD3, lysozyme, Ki-67, IgM, IgG, kappa, lambda and EBNA-2. Combining histological and immunohistological results, the lymphomas could be differentiated into two low-grade T-cell lymphomas and one high-grade multicentric polymorphic B-cell lymphoma. This corresponds to a 1.4% incidence of lymphomas in our cotton-top tamarin population over a period of 19 years. Although frozen material was not available and virological testing could not be carried out, clinical or histological evidence did not support an aetiological role of Herpes (H.) saimiri, H. ateles, simian T-cell leukaemia virus type 1 (STLV-1) or Epstein-Barr-related herpesvirus in any of these cases. The lymphomas were considered to be spontaneous.

Defense against influenza A virus infection: essential role of the chemokine system

Monocytes/macrophages are highly susceptible to an infection with influenza A virus. After infection, de novo virus protein synthesis is detectable but rapidly interrupted before completion of the first viral replication cycle. Within 24-48 hours the infected monocytes die by apoptosis. Before cell death, infected monocytes initiate a cell-specific immune response. This includes the transcription and subsequent release of TNF-alpha (tumor necrosis factor alpha), IL-1beta (Interleukin 1beta), IL-6, type I inferferons and CC chemokines. Enhanced cytokine mRNA expression is due to a prolonged mRNA stability and an augmented gene transcription. Activation of transcription factors such as NF-kappaB (nuclear factor kappaB) and AP-1 are involved in activation of cytokine mRNA transcription. Infection of monocytes with influenza A virus induces the selective expression of mononuclear leukocyte attracting chemokines, such as MCP-1 (monocyte chemotactic protein 1), MIP-1alpha (macrophage inflammatory protein 1alpha) and RANTES (regulated upon activation, normal T cell expressed and secreted). In striking contrast, the release of the neutrophil-specific chemokines IL-8 (interleukin 8) and GRO-alpha (growth stimulatory activity alpha) is entirely suppressed. This differentially regulated chemokine expression may explain the mononuclear cell infiltrate characteristic for virus-infected tissue. Thus, infection of monocytes/macrophages with influenza A virus primes for a rapid proinflammatory reaction and induces an enhanced immigration of mononuclear cells into infected tissue. Taken together, these mechanisms may prepare the infected host for a fast and virus-specific immune response.

Catalyst screening by electrospray ionization tandem mass spectrometry: Hofmann carbenes for olefin metathesis

A new screening methodology, which combines in situ synthesis of complexes with an assay by electrospray ionization tandem mass spectrometry (ESI-MS), is introduced in order to investigate highly active, cationic ruthenium-carbene catalysts in ring-opening metathesis polymerization (ROMP). The parameter space, whic is defined by systematic variation of four structural features of the catalyst [[R2P(CH2),PR2-kappa2-P]XRu=CHR']+ (the halogen ligand, the diphosphane bite-angle, the steric bulk of the phosphane, and the carbene ligand) and the variation of the metathesis substrate, is mapped out. Chloride as the anionic ligand X, a small chelating angle (n = 1), and reduced steric demand of the substituents R (Cy versus tBu) lead to the most reactive complex in acyclic olefin metathesis, whereas variation of the carbene moiety CHR' has only a modest influence. The overall rate in the gas phase depends on the pi-complex preequilibrium and metallacyclobutane formation, which was found to be the rate-determining step. In ROMP reactions backbiting has a profound influence on the overall rate. Moreover, we were able to establish that the reactivity trends determined in the gas phase parallel solution-phase reactivity. The overall rate in solution is also determined by a favorable dimer/ monomer preequilibrium providing the active catalyst by facile dissociation of dicationic, dinuclear catalyst precursors.

%HRmax target heart rate is dependent on heart rate performance curve deflection

The percent of maximal heart rate (%HRmax) model is widely used to determine training intensities in healthy subjects and patients when prescribing training intensities in these groups of subjects.

PURPOSE

The aim of the study was to investigate the influence of the time course of the heart rate performance curve (HRPC) on the accuracy of target training heart rate.

METHODS

Sixty-two young healthy male subjects performed an incremental cycle ergometer exercise test until voluntary exhaustion. Subjects were then divided into four groups according to the time course of the HRPC. Groups were classified in regular HR response (kHR2 > 0.2), indifferent HR response (0 < kHR2 < 0.2), linear HR response (kHR2 = 0), and inverted HR response (kHR2 < 0). The first and the second lactate turn point (LTP1, LTP2) as well as the heart rate turn point (HRTP) were determined as submaximal markers of performance. Linear regression lines were calculated for HR in the three regions of energy supply defined by LTP1 and LTP2.

RESULTS

HR at LTP1 and HRmax was not significantly different between all four groups. HR at LTP2 was dependent on the time course of the HRPC and was significantly lower (P < 0.05) as kHR2 decreased. Power output and blood lactate concentration at LTP1, LTP2 and maximal workload (Pmax) were not significantly different between the groups.

CONCLUSION

From our data, we conclude that target training HR detected by means of the %HRmax method may be overestimated in cases where the HR response is not regular, as it was found in many of our subjects.

Suppression of proinflammatory cytokines and induction of IL-10 in human monocytes after coxsackievirus B3 infection

Coxsackievirus B3 (CVB3) causes acute and chronic myocarditis, which is accompanied by an intense mononuclear leukocyte infiltration. Because myocardial tissue damage may either result from viral infections or from a dysregulated immune response, the susceptibility of human monocytes and macrophages to CVB3 was examined in this study with regard to virus replication, virus persistence, and release of cytokines. Monocytes were infected by CVB3 as shown by the intracellular appearance of plus- and minus-strand viral RNA, which was also capable of persisting for more than 10 days. Fresh monocytes were not permissive for full virus replication whereas monocyte-derived macrophages yielded a low amount of new viruses, which led to cell death. Although CVB3 infection induced the mRNA for the proinflammatory cytokines tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1, and IL-6, only little cytokine production occurred. When infected monocytes were stimulated in addition by lipopolysaccharides (LPS), cytokine production was partially suppressed. In striking contrast, IL-10 expression was strongly and persistently induced by CVB3 on the mRNA and the protein level. These data show a dysregulated cytokine response in CVB3-exposed human monocytes and macrophages, which is characterized by a suppression of proinflammatory cytokines and a dominance of IL-10. This viral strategy may aid CVB3, causing chronic myocardiopathy.

First outbreak of callitrichid hepatitis in Germany: genetic characterization of the causative lymphocytic choriomeningitis virus strains

Callitrichid hepatitis (CH) is a highly fatal, rodent-borne zoonosis of New World primates (family Callitrichidae) caused by lymphocytic choriomeningitis virus (LCMV). It is unclear whether virulence in Callitrichidae is associated with specific genetic or phylogenetic markers of the virus as only a partial S RNA sequence of a single CH-associated isolate is known. In a period of 10 months, three pygmy marmosets (Cebuella pygmaea) and one Goeldi's monkey (Callimico goeldii) died from CH in a German zoo. LCMV was most likely transmitted by wild mice. Infection was associated with characteristic histopathological lesions in liver, brain, and lymphoid tissue. Virus sequences from all callitrichids and a captured mouse were > or =99.2% identical. LCMV strains from a pygmy marmoset and the Goeldi's monkey were isolated in cell culture and the 3.4-kb S RNA was completely sequenced. Both strains differed considerably in their genetic and phylogenetic characteristics from known LCMV strains, including the previously described CH-associated strain. These data show that CH is widespread and can be caused by distantly related LCMV strains.

A physiological profile of tennis match play

PURPOSE

The aim of this investigation was to examine physiological demands of single match play in tennis.

METHODS

20 players performed 10 matches of 50 min. Respiratory gas exchange measures (RGEM) and heart rates (HR) were measured using two portable systems. Lactate concentration was determined after each game. The average oxygen uptake (VO2) of 270 games was 29.1 +/- 5.6 mL.kg-1.min-1 (51.1 +/- 10.9% of VO2max). Average VO2 for a game ranged from 10.4 to 47.8 mL.kg-1.min-1 (20.4 and 86.8% of VO2max). Average lactate concentration (LA) was 2.07 +/- 0.9 mmol.L-1 (ranging from 0.7 to 5.2 mmol.L-1). Furthermore, we monitored the duration of rallies (DR), the effective playing time (EPT), and the stroke frequency (SF). The average values of 270 games were DR: 6.4 +/- 4.1 s, EPT: 29.3 +/- 12.1%, SF: 42.6 +/- 9.6 shots.min-1.

RESULTS

Multiple regression revealed that the DR was the most promising variable for the determination of VO2 in match play (r = 0.54). The body surface area (BSA) and EPT were also entered into the calculation model. In games of two defensive players, VO2 was significantly higher than in games with at least one offensive player.

CONCLUSION

Our results suggest that energy demands of tennis matches are significantly influenced by DR. The highest average VO2 of a game of 47.8 mL.kg-1.min-1 may be regarded as a guide to assess endurance capacity required to sustain high-intensity periods of tennis matches compared with average VO2 of 29.1 mL.kg-1.min-1 for the 270 games. Our results suggest that proper conditioning is advisable especially for players who prefer to play from the baseline.

Sound attenuation of polymerizing actin reflects supramolecular structures: viscoelastic properties of actin gels modified by cytochalasin D, profilin and alpha-actinin

Polymerization and depolymerization of cytoskeletal elements maintaining cytoplasmic stiffness are key factors in the control of cell crawling. Rheometry is a significant tool in determining the mechanical properties of the single elements in vitro. Viscoelasticity of gels formed by these polymers strongly depends on both the length and the associations of the filaments (e.g. entanglements, annealings and side-by-side associations). Ultrasound attenuation is related to viscosity, sound velocity and supramolecular structures in the sample. In combination with a small glass fibre (2 mm x 50 microm), serving as a viscosity sensor, an acoustic microscope was used to measure the elasticity and acoustic attenuation of actin solutions. Changes in acoustic attenuation of polymerizing actin by far exceed the values expected from calculations based on changes in viscosity and sound velocity. During the lag-phase of actin polymerization, attenuation slightly decreases, depending on actin concentration. After the half-maximum viscosity is accomplished and elasticity turns into steady state, attenuation distinctly rises. Changes in ultrasound attenuation depend on actin concentration, and they are modulated by the addition of alpha-actinin, cytochalasin D and profilin. Thus absorption and scattering of sound on the polymerization of actin is related to the packing density of the actin net, entanglements and the length of the actin filaments. Shortening of actin filaments by cytochalasin D was also confirmed by electron micrographs and falling-ball viscosimetry. In addition to viscosity and elasticity, the attenuation of sound proved to be a valuable parameter in characterizing actin polymerization and the supramolecular associations of F-actin.

Immunohistochemical detection of simian immunodeficiency virus (SIV) in rectal mucosa of experimentally infected rhesus macaques (Macaca mulatta)

Experimental simian immunodeficiency virus (SIV) infection is the most appropriate animal model for human HIV infection. Eight male rhesus monkeys (Macaca mulatta) were intravenously or intrarectally infected with SIVmac251/MPBMC to comparatively investigate the distribution and spread of the virus within the rectum during the course of the disease. SIV-positive cells were immunohistochemically detected in rectal biopsies obtained at days 3 and 7 and week 2, 4 and 12 postinfection. SIV-expressing cells were detected for the first time at one week after experimental infection and were present in the lamina propria and lymph follicles. Numbers of positive cells per individual animal varied strongly in time, with a more rapid rise in animals with rapid progression of the disease. Differences were not observed between intravenous and intrarectal infection. Our observations support the significance of the intestinal tract as target organ in initial pathogenesis of SIV infection.

Prolactin and beta-endorphin serum elevations after ECT in manic patients

OBJECTIVE

Alterations in prolactin and beta-endorphin serum levels after ECT are well-established findings in depression. The present study focuses on electroconvulsive therapy (ECT) response patterns of the mentioned parameters in patients suffering from acute mania.

METHOD

Following the first three ECTs of a treatment series in 19 patients diagnosed according to DSM-III-R criteria as suffering from mania, blood samples were drawn before, and 20, 30 and 40 minutes after ECT. Serum prolactin and beta-endorphin levels were established in order to gain information about the effects of ECT on different neurotransmitter systems.

RESULTS

A significant transient increase in serum prolactin after ECT was found. Furthermore, in females but not males, delta(max)prolactin diminished over the course of treatment as prolactin baseline levels increased. beta-endorphin levels showed a stable transient increase after ECT stimulus regardless from sex or treatment.

CONCLUSION

The reported findings reflect those established in depression. This suggests that they are epiphenomenal to ECT.

Change in left atrial and ventricular dimensions during and immediately after exercise

PURPOSE

The aim of this study was to evaluate differences in the left atrial (LAD), total ventricular end-diastolic (TEDD), end-systolic diameters (TESD), and left ventricular shortening fraction (SF) compared with heart rate (HR) and systolic blood pressure (SBP) during exercise and recovery.

METHODS

Healthy young male (N = 15) and female (N = 16) subjects performed an incremental cycle ergometer test in upright position, and three phases of energy supply were defined by means of blood lactate concentration (LA) and respiratory gas exchange variables (I: aerobic; II: aerobic-anaerobic transition; III: anaerobic). Subjects were required to rest their arms on a steering bar and to lean their upper body forward; two dimensional (2-D) echocardiograms were obtained over the left parasternal area at rest (R), at the end of each phase, immediately within 15 s post, and 6 min after exercise (6 min). By using VINGMED's "Anatomical M-Mode," it was possible to extract M-Mode Sweeps from stored 2-D-Loops and perform the M-Mode measurement.

RESULTS

In contrast to the significant decrease in TEDD and TESD from III to 15 s up to resting values and the significant increase in SF from III to 15 s, the moderate decrease in HR immediately post exercise (15 s) was not significant. The SBP showed a significantly decrease from III to 15 s; in contrast to TEDD, TESD, and SF, the values at 15 s were comparable with the values at II. For LAD, significant increase during exercise and a decrease during recovery were observed. Sex-specific differences of changes in measured variables could not be found.

CONCLUSION

We concluded that post exercise measurement of left ventricular and atrial dimensions or SF were not valid to describe heart function at maximal exercise although immediately post exercise HR was near maximal level.

[Performance enhancement through training at medium altitude-- from the perspective of sports medicine]

In the last 20 years, maximal oxygen uptake (VO2max) of athletes in different sport disciplines has increased, and the world records in endurance sports have improved markedly. One of the factors that has influenced the increase in endurance performance has been perceived to be altitude training. In this paper we describe the advantages and disadvantages of a "regular" altitude training (live high/train high) aiming to improve sea level performance and compare it with a new method, the so called "live high/train low" method. This method uses the advantages and avoids the side effects of altitude exposure. Several papers have shown that altitude training is able to improve VO2max but the individual response may be substantially different. In most cases it is not possible to prove statistical significance and therefore we have no data about differences between both altitude training methods. However, it is suspected that the risk of overtraining is reduced in the high/low method. Although not statistically significant it is suggested that the "high/low" method can more efficiently improve endurance performance at sea level. A monitoring of submaximal variables of exercise performance is recommended to avoid overtraining and to control the development of performance. From the current knowledge the "live high/train low" method is suggested to be the more effective altitude training method for athletes.

[Total hysteroscopic endometrium resection: a critical analysis of indications, technique and results]

130 total hysteroscopic resections of the endometrium (RE) were performed at the Department of Gynecology and Obstetrics of the Deutschlandsberg Hospital from August 1, 1992 to May 31, 1997. 115 patients (88.5%) suffered from distinctive therapy-resistant uterine bleeding in terms of hypermenorrhea and menorrhagia, frequently combined with poly- and dysmenorrhea. 15 (11.5%) women who had previously been operated for breast cancer developed--during continuous treatment with tamoxifen--endometrial hyperplasia or polyps on which RE was performed after a hysteroscopic biopsy or resection had been carried out in a second setting. The operation showed that 98 out of 115 patients (85.2%) had pathologic anomalous uteri which were the organic cause of the uterine bleeding. Only 17 women (14.8%) suffered from dysfunctional uterine bleeding (12 cases) or from iatrogenically reduced coagulability (5 cases). The majority of the women (106 cases = 81.5%) were older than 40 (average 46.9 +/- 6.21 years). All RE were performed under inhalation anesthesia whereby the complete uterine cavity up to the inner orifice of the uterus was resected with the resectoscope loop. 92 out of 130 patients (70.8%) underwent a hysteroscopy or a dilatation and curettage before the RE. 77 patients (66.9%) received pretreatment with drugs to reduce the endometrium. 15 women (13.0%) underwent a laparoscopic tubal sterilization in the same setting. Finally, the results of 107 patients were analyzed excluding dropouts and patients who had undergone continuous treatment with tamoxifen and those who had an observation time of less than 6 months. After an observation period of 6-58 months, the success rate was 84.1%. For treatment of relapses 7 second resections were performed, whereby in 1 patient with a further uterine bleeding the uterus had to be extirpated. Nine of the 10 remaining patients had a hysterectomy, 1 patient refused any further treatment. The total hysterectomy rate was 12.2%. Basically, RE is absolutely practicable as far as the treatment of abnormal uterine bleeding is concerned, since hysterectomy can be avoided in a number of cases. Satisfactory long-term results, however, can only be achieved if indication and operation technique are of high quality. A problem which has not yet been solved is the indication and treatment of proliferating adenomyosis uteri interna.

Total numbers of lymphocyte subsets in different lymph node regions of uninfected and SIV-infected macaques

Human immunodeficiency virus (HIV) infection leads to a decline of CD4+ T-cells in blood. Because blood represents only a small proportion of the total lymphocyte pool, it is important to investigate other lymphoid organs. So far, only relative proportions of lymphocyte subsets in single peripheral lymph node (LN) regions of HIV-infected patients and simian immunodeficiency virus (SIV)-infected macaques have been documented. We have therefore quantified the absolute numbers of lymphocyte subsets in blood and six different LN regions of 10 uninfected and 26 SIV-infected macaques. In addition, we have determined the expression of markers of activation and differentiation. Already, in uninfected monkeys, there were significant differences in the cellular composition of different LN regions. Infection with SIV resulted in drastic changes in the proportion as well as absolute numbers of different lymphocyte subsets. Moreover, the relative contribution of the single LN regions to the total lymphocyte pool was also altered.

Cytokine profiles in heart, spleen, and thymus during the acute stage of experimental coxsackievirus B3-induced chronic myocarditis

Since cytokines play an important role in the pathogenesis of virus-induced chronic heart diseases, cytokine mRNA expression was studied in coxsackievirus B3-infected NMRI mice during the acute phase of myocarditis until the onset of chronic cardiac disease. Virus replication, cytokine induction, inflammatory cell infiltration and myocardial damage were studied by titer determination, reverse transcription-polymerase chain reaction (RT-PCR), and histopathology. To investigate whether the coxsackievirus B3-induced cytokine mRNA accumulation was only limited to the heart or generalized, spleen and thymus specimens were also included. Surprisingly, interleukin (IL)-10 as a deactivator of T cell and macrophage functions was transcribed in the myocardium nearly in parallel with virus replication from Day 1 through Day 14. At Day 3 p.i., the mRNA of IL-1alpha, tumor necrosis factor (TNF)-alpha, IL-6, and interferon (IFN)-beta accumulated. At Days 4, 7, and 14, IL-12-specific mRNA was produced. Furthermore, increasing amounts of IFN-gamma mRNA were found, whereas IL-2 and IL-4 mRNA remained undetectable. TNF-alpha, IL-1alpha, IL-10, IL-12, and IFN-gamma mRNA persisted into the late stage of myocarditis. In the spleen a closely correlated expression of virus and IL-10-specific mRNAs was also found, and in addition, IFN-beta, TNF-alpha, and IL-6 were detected. In striking contrast to heart and spleen tissue, the distinct expression of viral RNA in the thymus was not accompanied by an increased cytokine mRNA production. These data provide evidence for a unique coxsackievirus B3-induced cytokine pattern in the myocardium and spleen and suggest that persistently expressed IL-10 may play a leading role in acute and chronic myocarditis by subverting the immune response.

Selective induction of the monocyte-attracting chemokines MCP-1 and IP-10 in vesicular stomatitis virus-infected human monocytes

It is characteristic of viral infections that monocytes/macrophages and lymphocytes infiltrate infected tissue, and neutrophils are absent. CC and non-ELR CXC chemokines predominantly attract mononuclear leukocytes, whereas the ELR motif-expressing CXC chemokines primarily act on neutrophils. To investigate the general role of chemokines in viral diseases, we determined their release and expression patterns after infection of human monocytes with vesicular stomatitis virus (VSV). Human monocytes were productively infected by VSV. Surprisingly, VSV did not induce the release of the proinflammatory cytokines tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and IL-6. In contrast, we found a strong induction of the CC chemokine monocyte chemotactic protein-1 (MCP-1) and the non-ELR CXC chemokine interferon-gamma (IFN-gamma) inducible protein-10 (IP-10) by VSV on the gene and protein level. The expression and release of the neutrophil chemoattractants IL-8 and growth-related oncogene-alpha (GRO-alpha) remained unaffected after VSV infection. Our results indicate that the typical monocyte and lymphocyte-dominated leukocyte infiltration of virus-infected tissue is based on a selective induction of mononuclear leukocyte-attracting chemokines.

A trigonal planar mu 3-fluorido coinage metal complex from a dicationic (diphosphinomethane)copper(I) dimer: syntheses, structures, and bonding

The triflate and hexafluorophosphate salts of [Cu2(mu-dtbpm)2]2+ (1(2+)) [dtbpm = bis(di-tert-butylphosphino)methane, tBu2PCH2PtBu2] and of [Cu3(mu 3-F)(mu-dtbpm)3]2+ (2(2+)) were synthesized and characterized. Coordination of solvent or counterions to 1(2+) is observed neither in solution nor in the solid state. The two copper(I) centers in 1(2+) indicate weak d10-d10 closed-shell interactions. 1(2+) reacts slowly with PF6- anions in acetone or KF in CH2Cl2 to yield the mu 3-fluorido complex 2(2+) with idealized D3 symmetry, containing a trigonal planar Cu3F core, as shown by single-crystal X-ray diffraction. Distinct structural differences are observed compared to monocationic bicapped, trinuclear copper(I) dppm halide complexes [dppm = bis(diphenylphosphino)methane, Ph2PCH2PPh2]. The average Cu-Cu, Cu-F, and Cu-P distances and the P-Cu-P' angle in 2(2+) are 3.85, 2.22, and 2.28 A and 144.3 degrees, respectively. The P2Cu units are twisted out of the Cu3F plane by an average angle of 18.4 degrees. DFT calculations (BPW91/LANL2DZ) for the model [Cu3(mu 3-F)(mu-dhpm)3]2+ (dhpm = diphosphinomethane, H2PCH2PH2) are used to explain the formation, structure, and bonding pattern of 2(2+).

Phenotype, intestinal morphology, and survival of homozygous and heterozygous endothelin B receptor--deficient (spotting lethal) rats

BACKGROUND/PURPOSE

Spotting lethal (sl) rats, a model for Hirschsprung's disease, recently have been found to carry a deletion in the endothelin B (ET(B)) gene, causing functional lack of ET(B) receptors. The ET(B) receptor mediates, together with and in counterbalance to the ET(A) receptor, endothelin actions on vessels, cell proliferation, and migration. The authors investigated the effect of homozygosity (sI/sI) or heterozygosity (+/sl) on phenotype, intestinal morphology, and survival.

METHODS

Weight, circumference, and serum albumin were measured. Histological tests of major organs and immunoperoxidase reaction for Peripherin, glial fibrillary acid protein (GFAP), and S-100 in small and large intestine were performed. Peripherin-immunostained sections of colon and jejunum were analyzed morphometrically. Screening for sepsis included search for enterocolitis, bacterial infection, endotoxin, and iNOS mRNA.

RESULTS

Sl/sl rats died within 4 weeks of life, showing an early and a later death group. Serum albumin levels were decreased in sl/sl rats, whereas signs of sepsis were rare. Immunostaining uncovered alterations in nerve and glial cells in the whole gut of sl/sl rats, and to a subtle degree also in +/sl rats, which appear clinically normal. Morphometric quantification yielded statistically significant alterations in sl/sl rats only. No obvious abnormalities were found in other organs.

CONCLUSIONS

Sl/sl rats die from malnutrition rather than sepsis, too early for ischemic complications to occur. Rats of the later death group are a suitable model for studying the ET8 receptor in vivo. Subtle abnormalities in the enteric nervous system of heterozygous rats underline the critical role of the "gene dose" for functional compensation.

[Hypophyseal-hypothalamo-thyroid axis in affective disorders]

For centuries there has been convincing evidence that diseases of the thyroid gland may produce psychiatric symptoms. Nowadays systematic data are available concerning a higher incidence of thyroid diseases in psychiatric patients and vice versa a higher incidence of psychiatric disorders in thyroid patients. A more subtle approach concerns challenge tests like the TRH test. It could be shown that depressive patients show a blunted TSH response to TRH in 30-40% of the cases. This might lead to a definition of a subgroup of depressives from a psychoneuroendocrinological point of view. But it also might have an impact on the prediction of treatment outcome in psychopharmacological treatment approaches.

CD2-mediated CD59 stimulation in keratinocytes results in secretion of IL-1alpha, IL-6, and GM-CSF: implications for the interaction of keratinocytes with intraepidermal T lymphocytes

Normal epidermal keratinocytes are here shown to express membrane-associated complement inhibitory protein CD59 in vitro that protects keratinocytes from damage by complement because preincubation with blocking antibodies to CD59 renders the cells susceptible to complement mediated lysis. CD59 expression in keratinocytes is constitutive and not modulated by inflammatory cytokines, phorbol myristate acetate (PMA), and a number of other agents tested. Antibody mediated cross-linking of CD59, however, revealed an additional function of CD59: keratinocytes in vitro are activated to secrete the cytokines IL-1alpha, IL-6, and GM-CSF. CD59 mediated induction of these cytokines is regulated at the transcriptional level. Binding of keratinocytes to HL60 cells that express CD59 ligand CD2 induced the same pattern of secreted cytokines whereas binding to CD2-negative HL60 cells did not. Induction of cytokine secretion was completely blocked by preincubation of keratinocytes with both anti-CD58 and anti-CD59 antibodies together. The results demonstrate that CD2-mediated CD59 stimulation in human keratinocytes leads to synthesis of a particular set of cytokines implying a potential activation pathway in the interaction of keratinocytes with intraepithelial CD2+ T cells.

The heart rate turn point reliability and methodological aspects

PURPOSE

The aim of the study was to test protocol variations on the heart rate performance curve (HRPC) and the heart rate turn point (HRTP) according to Conconi et al. (1996). Respiratory gas exchange variables were used to define three phases of energy supply (I, II, III).

METHODS

Eighteen healthy young male subjects performed 4 tests (T1-T4). T1: initial speed of 6 km x h(-1) followed by increments of 0.6 km x h(-1) every 60 s. Subjects were than randomized for the next three tests. T2: initial speed 5.6 km x h(-1) followed by increments of 0.2 km x h(-1) every 20 s; T3: similar to T2, in the second half of phase III acceleration (S) was increased. T4: like T2, at the beginning of phase III, S was increased. No differences were found in the degree of the deflection of the HRPC expressed as factor kHR between T1 (0.228 +/- 0.225) and T2 (0.248 +/- 0.231) but a significant increase was found in T3 (0.533 +/- 0.248) and T4 (0.770 +/- 0.258).

RESULTS

The modifications of the protocol (T3 and T4) systematically influenced the deflection of the HRPC, but kHR was highly reproducible in all tests. Eleven subjects showed degrees of deflection in the HRPC in all tests. There were no significant differences for S, HR, and VO2 at the HRTP. An HRTP was not found in seven subjects in neither T1 or T2; however, in T3 and T4, these seven subjects showed a deflection of HRPC resulting from the protocol. The HRTP was found to be dependent on the start of the acceleration in phase III. In cases with a linear time course in the HRPC in T1 and T2, in T3 an HRTP was found at 15.6 km x h(-1) and in T4 at 13.6 km x h(-1) , respectively.

CONCLUSION

The Conconi test protocol with an accelerated increase in S in the final phase of the test has a major influence on the occurrence of the HRTP in cases of near linear HRPC.

The heart rate performance curve and left ventricular function during exercise in patients after myocardial infarction

PURPOSE

The aim of the study was to investigate the heart rate turn point (HRTP) in the time course of the heart rate performance curve (HRPC) in patients after myocardial infarction, and the relationship between the HRTP, the left ventricular function, and the second lactate turn point (LTP2).

METHODS

We studied the degree and the direction of the HRPC and the left ventricular ejection fraction (LVEF) in 49 male patients 57 +/- 8 d after their first posterior wall infarction (MI). An incremental cycle ergometer test was performed and three phases of energy supply were defined (I: aerobic; II: aerobic-anaerobic transition; III: anaerobic) via blood lactate LA concentration. HRTP and LVEF-turn points (LVEFTP) were assessed by linear turn point analysis. The degree and direction of the deflection of HRPC were described as factor k (k > 0.1: downward deflection; -0.1 < k < 0.1: linear time curse; k < -0.1: upward deflection). The LVEF was determined by RNA. The difference between Pmax and LTP2 was calculated for LVEF (delta LVEF).

RESULTS

An HRTP could be found in 44 and a LVEFTP in 47 cases. The HRTP occurred at 85 +/- 17 Watt (W), which correlated (r = 0.95; P < 0.001) with the LTP2 (84 +/- 17 W) and the LVEFTP (84 +/- 17 W, r = 0.93; P < 0.001). From LTP2 to Pmax a significant decrease in LVEF was found. There was a correlation between the percentage of HRmax at the HRTP and k (r = 0.70), as well as delta LVEF (r = 0.56).

CONCLUSIONS

To prevent myocardial overloading, it seems to be useful to determine the HRTP, which indicate the workload where LVEF decreases.

DARA vestibular equipment onboard MIR

In space, the weightless environment provides a different stimulus to the otolith organs of the vestibular system, and the resulting signals no longer correspond with the visual and other sensory signals sent to the brain. This signal conflict causes disorientation. To study this and also to understand the vestibular adaptation to weightlessness, DARA has developed scientific equipment for vestibular and visuo-oculomotoric investigations. Especially, two video-oculography systems (monocular--VOG--and binocular--BIVOG, respectively) as well as stimuli such as an optokinetic stimulation device have successfully been employed onboard MIR in the frame of national and European missions since 1992. The monocular VOG was used by Klaus Flade during the MIR '92 mission, by Victor Polyakov during his record 15 months stay onboard MIR in 1993/94 as well as by Ulf Merbold during EUROMIR '94. The binocular version was used by Thomas Reiter and Sergej Avdeyev during the 6 months EUROMIR '95 mission. PIs of the various experiments include H. Scherer and A. Clarke (FU Berlin), M. Dieterichs and S. Krafczyk (LMU Munchen) from Germany as well as C.H. Markham and S.G. Diamond from the United States. Video-Oculography (VOG) is a technique for examining the function of the human balance system located in the inner ear (vestibular system) and the visio-oculomotor interactions of the vestibular organ. The human eye movements are measured, recorded and evaluated by state-of-the-art video techniques. The method was first conceived and designed at the Vestibular Research Laboratory of the ENT Clinic in Steglitz, FU Berlin (A. Clarke, H. Scherer). Kayser-Threde developed, manufactured and tested the facilities for space application under contract to DARA. Evaluation software was first provided by the ENT Clinic, Berlin, later by our subcontractor Sensomotoric Instruments (SMI), Teltow. Optokinetic hardware to support visuo-oculomotoric investigations, has been shipped to MIR for EUROMIR '95 and has successfully been used in conjunction with VOG by ESA astronaut Thomas Reiter. Most recently, BIVOG aboard MIR will be reused in the frame of German/Russian joint experiment sessions employing two Russian cosmonauts from August 1997 to January 1998.

Protective effects of fruits and vegetables against in vivo clastogenicity of cyclosphosphamide or benzo[a]pyrene in mice

Seven fruits and 10 vegetables commonly consumed in Germany were investigated for their anticlastogenic potencies against cyclophosphamide (CP) and benzo[a]pyrene (BaP) in the in vivo mouse bone marrow micronucleus assay. We detected protective effects in 76.5% and 70.6% of the samples, respectively, and more or less distinct quantitative differences between the various plant materials and the two clastogens investigated. With respect to CP, moderate activities were exerted by sweet cherries, strawberries, cucumber, radish and tomatoes, average activities by bananas, oranges, peaches, asparagus and red beets and strong activities by yellow red peppers and especially spinach. Apples (cultivar Jona Gold), brussels sprouts, cauliflower and onions were inactive. With respect to BaP, we found moderate activities in strawberries, brussels sprouts and radish, average activities in sweet cherries, oranges, peaches, asparagus, red beets, cucumber and spinach and strong activities in bananas and kiwi. Apples, cauliflower, onions, tomatoes and yellow-red peppers were inactive. When oranges were fractionated according to previously described schemes (Edenharder et al., 1995), anticlastogenic activities against CP were exerted by materials extracted with n-hexane, acetone and 2-propanol and in the terminal residue, but not in the dichloromethane and water phases. With respect to BaP, materials extracted with acetone showed strong anticlastogenicity while the 2-propanol fraction, the aqueous phase and the terminal residue were less potent. The n-hexane and the dichloromethane fractions were inactive. In red beets, all fractions showed anticlastogenicity against CP and BaP as well. However, the n-hexane and dichloromethane fractions were most potent with respect to CP, while for BaP the aqueous phase and the terminal residue were most effective. These result suggest the presence of various (groups of) anticlastogenic compounds with different chemical structure.

Parasympathetic receptor blockade and the heart rate performance curve

Parasympathetic receptor blockade and the heart rate performance curve. Med. Sci Sports Sci., Vol. 30. No. 2, pp. 229-233, 1998. The aim of the present study was to investigate the influence of parasympathetic receptor blockade on the heart rate performance curve (HRPC). Twenty healthy male subjects performed a first cycle ergometer test (F), showing a HRPC deflection of varying degree and direction. Subjects then in random order performed two additional cycle ergometer tests, one with atropine (A) and the other with placebo (P). Two lactate turn points (LTP1, and LTP2) were determined by means of linear regression turn point analysis. The degree and direction of the deflection of the HRPC was calculated mathematically as factor kHR (kHR>0 = downsloping of HPRC; kHR<0 = upsloping of HRPC). In comparison with that in F and P, HR in A was significantly higher at rest, LTP1, LTP2, and during recovery, but not at Power(max). An upsloping deflection of the HRPC was seen in only five cases in F and P, whereas in A 10 cases were observed (P < 0.05). In A, kHR was significantly lower than in F and P. A significant correlation for kHR was found among F, P, and A. Independent from parasympathetic receptor blockade and the HR at Power(max), the HR at LTP2 was lower in cases with negative kHR (upsloping). In A as well as in P a significant correlation was observed between kHR and HR at LTP2. The individual time course of HRPC is reproducible and may be independent of parasympathetic activity.