Blood ammonia and lactate concentrations during endurance exercise of differing intensities

Summary The purpose of this study was to examine the changes of blood ammonia concentration ([NH₃]_b) during endurance exercise of differing intensities on the cycle ergometer and to compare [NH₃]_b to the changes observed in the simultaneously monitored blood lactate acid concentrations ([la^–]_b) measurements. A group of 16 endurance-trained athletes participated in the first part of the study and performed exercise of 30 min duration in a randomized order at intensities of 85%, 95%, 100% and 105% of their individual anaerobic threshold (Th_an,ind; E85–E105) which had been determined beforehand by a cycle exercise test with stepwise increments in intensity. In the second part, 18 average endurance-trained sports students underwent exhausting intensive endurance exercise (IEE) with an intensity of 95% of Th_an,ind. An extensive endurance exercise (EEE) of the same duration at 85% of the Than,ind was carried out 2 days later. The [NH₃]_b increased constantly with increasing duration of all exercise. However, [la^–]_b only increased during exercise with intensities above the Th_an,ind (E105). The increase of [NH₃]_b was higher with higher exercise intensities. At IEE, [NH₃]_b was significantly higher from the 30th min than at EEE, whereas [la^–]_b increased from the 5th min. In conclusion, [la^–]_b responded more sensitively to the intensity of exercise than [NH₃]_b, but it is conceivable that in the future measurements of [NH₃]_b could be used to advise on the duration of endurance training. At present, however, the lack of experience and lack of appropriate values still hinders the systematic use of [NH₃]_b measurements in the physiological monitoring of sports training.     

Energy metabolism and regulatory hormones in women and men during endurance exercise

Summary Gender differences in the changes substrates of carbohydrate and lipid metabolism as well as in adrenaline, noradrenaline, growth hormone, insulin and cortisol were investigated in 24 women and 24 men during exhaustive endurance exercise. Training history and current performance capacity were taken into consideration in the design of the study. Since previous papers present conflicting results the purpose of the present study was to obtain further information regarding possible gender differences in lipid metabolism and its regulation by hormones. Non-endurancetrained women and men each ran 10 km on a treadmill at an intensity of 75% of ; endurance-trained women and men ran 14 and 17 km, respectively, at an intensity of 80% of . Blood glucose levels in non-endurance-trained women were higher when compared to non-endurance-trained men. This might be explained by increased mobilization of free fatty acids from intramuscular fat depots during energy production in non-specifically trained women. In contrast, no substantial gender differences in endurancetrained persons were seen in lipid metabolism. The changes in substrates of lipid metabolism confirm the higher lipolytic activity and greater utilization of free fatty acids in endurance-trained persons. During endurance exercise, changes in adrenaline, noradrenaline, growth hormone, insulin and cortisol were not substantially affected by the sex of the subjects. This study does not present any conclusive results that endurance-trained persons show gender differences in lipid metabolism and major regulatory hormones. Supported by the Bundesinstitut für Sportwissenschaft K?ln, FRG     

Why do patients seek treatment in hospitals of complementary medicine?

OBJECTIVE: This exploratory study evaluated patients' reasons for entering a complementary (alternative) medicine hospital by ranking 15 medical and psychosocial factors that were thought to influence this choice. SUBJECTS AND OUTCOME MEASURES: Two hundred patients (200) from two complementary hospitals, one focusing on Traditional Chinese Medicine and one on the Western type of complementary medicine, completed an extensive questionnaire at the beginning of their inpatient treatment. The questionnaire covered personal background; disease parameters; attitude towards conventional medicine; previous experience with, and knowledge of, complementary therapies; expectations concerning the forthcoming treatment; health-related habits; personality traits; and social support. RESULTS: Optimistic attitudes towards treatment and a positive appraisal of alternative doctors were frequently stated reasons (80%), as was the disease severity (long duration: 86%; acute progression or imminent surgery: 70%). Previous successes with complementary therapies, however, ranked relatively low (53%). Negative opinions concerning conventional therapies and conventional doctors' treatments were mentioned by 68% of the patients. Many patients felt themselves to be under considerable psychologic stress (74%). A majority (73%) was well informed about complementary therapies, and 65% were curious about the forthcoming therapies. Sixty-eight percent (68%) indicated good health behaviors. Fewer patients mentioned contemplative and/or religious attitudes (44%) or lack of social support (25%). Age primarily accounted for variations in the ranking weights of the two subgroups. The specific type of complementary medicine was of minor influence. In 14 out of 21 personality dimensions, the current patient group showed significant deviations from the healthy reference, which is in good agreement with findings from conventionally treated patients.     

Electrolyte-Stimulated Biphasic Dissolution Profile and Stability Enhancement for Tablets Containing Drug-Polyelectrolyte Complexes

Purpose

Recently introduced drug-polyelectrolyte complexes prepared by hot-melt extrusion should be processed to solid dosage forms with tailor-made release properties. Their potential of stability enhancement should be investigated.

Methods

Milled hot-melt extruded naproxen-EUDRAGIT? E PO polyelectrolyte complexes were subsequently processed to double-layer tablets with varying complex loadings on a rotary-die press. Physicochemical interactions were studied under ICH guideline conditions and using the Gordon-Taylor equation. Sorption and desorption were determined to investigate the influence of moisture and temperature on the complex and related to stability tests under accelerated conditions.

Results

Naproxen release from the drug-polyelectrolyte complex is triggered by electrolyte concentration. Depending on the complex loading, phosphate buffer pH 6.8 stimulated a biphasic dissolution profile of the produced double-layer tablets: immediate release from the first layer with 65% loading and prolonged release from the second layer within 24?h (98.5% loading). XRPD patterns proved pseudopolymorphism for tablets containing the pure drug under common storage conditions whereas the drug-complex was stable in the amorphous state.

Conclusions

Drug-polyelectrolyte complexes enable tailor-made dissolution profiles of solid dosage forms by electrolyte stimulation and increase stability under common storage conditions.     

Relationship between pulse transit time and blood pressure is impaired in patients with chronic heart failure

Aims

Pulse transit time (PTT), the interval between ventricular electrical activity and arrival of the peripheral pulse wave, has been used to detect changes in autonomic tone during sleep and anesthesia. The purpose of this study was to evaluate PTT in patients with chronic heart failure (HF).

Methods and results

Pulse transit time was measured with R-wave gated photoplethysmography in 24 healthy volunteers and in 112 patients with chronic HF and ejection fraction (EF) <40%. PTT was mildly elevated in patients with HF (468 ± 12 vs. 430 ± 23 ms, p = 0.001). In healthy volunteers, PTT was directly proportional to blood pressure (BP): when BP increased, PTT shortened, and vice versa. This relationship between PTT and BP (PTTi) was altered in patients with HF and particularly in the 26 patients with decompensated HF (3.6 ± 0.4 vs. 4.2 ± 0.9, p = 0.04). PTTi did not correlate with functional NYHA class and levels of pro-BNP, epinephrine or norepinephrine. There was a modest correlation between PTTi and EF (p = 0.01, r = ?0.48) and PTTi tended to correlate with microvascular flow measured with Laser Doppler (p = 0.08). However, there was an excellent correlation between PTTi and systolic time intervals, left ventricular ejection time (LVET) (p = 0.0014, r = ?0.75) and pre-ejection time/LVET (p = 0.006, r = 0.80). The latter ratio reflects ventricular–arterial coupling.

Conclusion

The relationship between PTT and BP is altered in severe HF and may indicate impaired ventricular–arterial coupling. It merits further investigation as both parameters can be easily determined and used for serial monitoring in HF.     

Volume vs. intensity in the training of competitive swimmers

The present study aimed at comparing a high-volume, low-intensity vs. low-volume, high-intensity swim training. In a randomized cross-over design, 10 competitive swimmers performed two different 4-week training periods, each followed by an identical taper week. One training period was characterized by a high-training volume (HVT) whereas high-intensity training was prevalent during the other program (HIT). Before, after two and four weeks and after the taper week subjects performed psychometric and performance testing: profile of mood states (POMS), incremental swimming test (determination of individual anaerobic threshold, IAT), 100 m and 400 m. A small significant increase in IAT was observed after taper periods compared to pre-training (+ 0.01 m/s; p = 0.01). Maximal 100-m and 400-m times were not significantly affected by training. The POMS subscore of "vigor" decreased slightly after both training periods (p = 0.06). None of the investigated parameters showed a significant interaction between test-time and training type (p > 0.13). Nearly all (83 %) subjects swam personal best times during the 3 months after each training cycle. It is concluded that, for a period of 4 weeks, high-training volumes have no advantage compared to high-intensity training of lower volume.