Bicarbonate ingestion has no ergogenic effect on consecutive all out sprint tests in BMX elite cyclists

The aim of the present study was to examine the effect of sodium bicarbonate ingestion on consecutive "all out" sprint tests, analyzing the acid-base status and its influence on performance and perceived effort. Ten elite bicycle motocross (BMX) riders (20.7 ± 1.4 years, training experience 8-12 years) participated in this study which consisted of two trials. Each trial consisted of three consecutive Wingate tests (WTs) separated by 15 min recovery. Ninety minutes prior to exercise subjects ingested either NaHCO(3) (-) (0.3 g kg(-1) body weight) or placebo. Blood samples were collected for the assessment of blood acid-base status: bicarbonate concentration ([HCO(3) (-)]), pH, base excess (BE) and blood lactate concentration ([La(-)]). Performance variables of peak power (PP), mean power (MP), time to peak power and fatigue index were calculated for each sprint. Significant differences (p < 0.05) were observed in acid-base variables [pH before WT1: 7.47 ± 0.05 vs. 7.41 ± 0.03; [HCO(3) (-)] before WT1: 29.08 ± 2.27 vs. 22.85 ± 0.24 mmol L(-1) (bicarbonate vs. placebo conditions, respectively)], but there were not significant differences in performance variables between trials [PP WT1: 1,610 ± 373 vs. 1,599 ± 370 W; PP WT2: 1,548 ± 460 vs. 1,570 ± 428 W; PP WT3: 1,463 ± 361 vs. 1,519 ± 364 W. MP WT1: 809 ± 113 vs. 812 ± 108 W; MP WT2: 799 ± 135 vs. 799 ± 124 W; MP WT3: 762 ± 165 vs. 782 ± 118 W (bicarbonate vs. placebo conditions, respectively)]. Rating of perceived effort (RPE) was not influenced nor ratings of perceived readiness. Sodium bicarbonate ingestion modified significantly the blood acid-base balance, although the induced alkalosis did not improve the Wingate test performance, RPE and perceived readiness across three consecutive WTs in elite BMX cyclists.     

Acute hypothyroidism has no effect on pulmonary vascular resistance

Summary The effect of acute hypothyroidism on the pulmonary circulation was studied in 9 nonobese athyreotic patients by right heart catheterization at rest and during exercise. The patients were studied while they were hypothyroid 2 weeks after ceasing triiodothyronine treatment and while they were euthyroid on replacement therapy. At rest, pulmonary blood flow [4.0±0.6 l/min vs 5.8±1.0 l/min,p<0.01] and systolic pulmonary artery pressure [18±3 mmHg vs 23±2 mmHg,p<0.01] were lower when the patients were hypothyroid than when they were euthyroid. The mean and diastolic pressures in the pulmonary artery and the pulmonary capillary pressures were not different among the groups. Likewise, thyroid hormone levels had no significant effect on pulmonary vascular resistance [100±25 dyn-s-cm^–5 vs 90±23 dyn-s-cm^–5]. With supine exercise, pulmonary blood flow [10.1±1.6 l/min vs. 13.2±2.0 l/min,p<0.01], mean pulmonary artery pressure [25±6 mmHg vs 30±6 mmHg,p<0.02], and systolic pulmonary artery pressure [36±6 mmHg vs 44±8 mmHg,p<0.01] were lower when the patients were hypothyroid. The diastolic pulmonary artery pressure and the pulmonary capillary pressure were similar in both thyroid states. Again, thyroid deficiency had no effect on pulmonary vascular resistance [81±23 dyn-s-cm^–5 vs 76±24 dyn-s-cm^–5]. The lower systolic pressures in the pulmonary artery seen in hypothyroidism are probably due to the decreased systolic volume load of the pulmonary circulation. The data do not suggest that thyroid hormones play a role in the regulation of pulmonary vascular resistance.Abbreviations PVR pulmonary vascular resistance - PAP_M mean pulmonary artery pressure - PCP_M mean pulmonary capillary pressure - PBF pulmonary blood flow     

Effect of acute and short-term oral salbutamol treatments on maximal power output in non-asthmatic athletes

This study aimed to clarify the controversial effects of acute and short-term salbutamol (SAL) intake on sprint performance in healthy athletes. Based on the results of previous studies, an anabolic effect for the short-term treatment and increased glycolysis in both treatments were hypothesized. Eight male recreational athletes completed force-velocity exercise tests after administration of placebo (gelatin), acute oral SAL (6 mg) or short-term oral SAL (12 mg day(-1) for 3 weeks), using a double-blind and randomized protocol. A friction-loaded cycle ergometer fitted with a strain gauge, and an incremental encoder ensured accurate measurement of the force-velocity relationship during sprints. Mechanical data were averaged during each pedal downstroke. Compared with placebo after both acute and 3 weeks of continuous treatment, the force-velocity relationship shifted to the right with power output gains of 14 and 8% (p < 0.001), respectively. This effect was less marked for 3 weeks of continuous treatment compared with acute administration (p < 0.001), suggesting a down-regulation in adrenoceptors. Our first hypothesis thus seems rejected. Significantly higher end-of-exercise and recovery blood lactate concentrations were found under SAL compared with placebo (p < 0.001), supporting our second hypothesis. In conclusion, these data indicate that oral administration of SAL is an effective ergogenic aid for sprint exercise in non-asthmatic athletes. Moreover, an acute treatment seems to be more effective than 3 weeks of continuous treatment.     

Sandostatin has no direct effect on ovarian steroidogenesis in vitro

Rat granulosa and theca—interstitial cells from immature,oestradiol-treated rats were isolated and incubated for 144h with follicle stimulating hormone (FSH), luteinizing hormone(LH), insulin alone or in combinations, and with two doses ofsandostatin (10^–7 M and 10^–6 M per culture). Oestradioland testosterone production by granulosa and theca—interstitialcells, respectively, was measured in culture media. The stimulatoryeffects of FSH alone and FSH with insulin but not insulin aloneon oestradiol production by granulosa cells were observed. Similarly,increased testosterone concentrations after treatment with LHalone and LH with insulin but not insulin alone were found inmedia from theca—interstitial cells. The addition of highor low doses of sandostatin to the cultures did not affect theproduction of oestradiol or testosterone. It was concluded thatsandostatin does not exert any direct effect on ovarian steroidogenesisin vitro.     

Miglustat has no apparent effect on spermatogenesis in normal men

BACKGROUND: In mice, administration of the glycosphingolipid biosynthesis inhibitor miglustat results in reversible infertility, characterized by impaired sperm motility and markedly abnormal sperm morphology. This observation suggested that miglustat might have utility for fertility control in man. To ascertain the impact of miglustat on human spermatogenesis, we conducted a pilot study of miglustat administration in normal men. METHODS: After a 2-week baseline period, seven normal men were administered miglustat 100 mg, orally, twice daily for 6 weeks. During treatment, subjects had frequent seminal fluid analyses to assess the impact of treatment on sperm concentration, motility and morphology and the ability to undergo the acrosome reaction by in vitro assays. RESULTS: Five subjects completed all aspects of the study. In these subjects, there was no apparent effect of miglustat on sperm concentration, motility or sperm morphology after 6 weeks of therapy. In addition, no changes in acrosome structure or function were observed with treatment, despite therapeutic concentrations of miglustat in the serum and seminal plasma. All subjects experienced gastrointestinal upset, diarrhoea and mild weight loss during treatment. No other abnormalities in blood counts, serum chemistries, vision or overall health were observed. CONCLUSION: In contrast to the observations in mice, the oral administration of miglustat does not appear to affect human spermatogenesis. Further elucidation of the mechanism underlying the species specificity of miglustat may improve our understanding of the role of glycosphingolipids in spermatogenesis and result in alternative approaches to male fertility control.     

Subchronic methylphenidate administration has no effect on locomotion,emotional behavior,or water maze learning in prepubertal mice

Methylphenidate hydrochloride (Ritalin, MPH) is frequently prescribed as a treatment for children with attention deficit hyperactivity disorder (ADHD), yet little research has been conducted to determine its potential long-term neurobehavioral effects. We assessed the effects of subchronic MPH administration (2.5, 5, 10, 20, 40, or 80 mg/kg) on male CD-1 mice treated from 26 to 32 days of age. When tested at 33 days of age in the open field and elevated plus maze, there were no significant differences in spontaneous locomotion, exploration, or fear- and anxiety-related behaviors. Testing from 34 to 37 days of age in a water maze task revealed no significant effects of any dose of MPH on learning in this simple paradigm. While it is difficult to extrapolate directly from these results to clinical effects in humans, our results indicate that preexposure of mice to MPH late in the postnatal developmental period does not appear to alter later behavior. We are currently conducting additional studies to further probe the potential effects of MPH administration during development and to examine various contributing factors including stage of development, duration of MPH administration, complexity of the task used to assess behavioral changes, and type of cognitive process being analyzed (attention, nonspatial working memory, etc.).     

The m protein of influenza viruses has no immunizing effect

Influenza A virus M protein was prepared by electrophoresis in SDS polyacrylamide gel from virus particles which had been pretreated with octylglucoside to remove the surface glycoproteins. M antigens from the influenza virus strains A/Victoria/3/75 (H3N2), A/FPV/Rostock (Hav1N1) and A/chick/ Germany/49 (Hav2Neq1) did not protect mice against a lethal challenge infection with the virulent Victoria strain.Supported by the Deutsche Forschungsgemeinschaft (Sonderforschungsbereich 47)     

Melatonin has no effect on tolerance to uncompensable heat stress in man

This study examined whether a 5 mg dose of melatonin induced a lower rectal temperature (T _re) response at rest in both a cool and hot environment while wearing normal military combat clothing, and then examined the influence of this response on tolerance to exercise in the heat while wearing protective clothing. Nine men performed four randomly ordered trials involving 2 h of rest at ambient temperatures of either 23 °C or 40 °C followed by exercise at an ambient temperature of 40 °C. The double-blind ingestion of placebo or melatonin occurred after 30 min of rest. The mean T _re during rest at 23 °C had decreased significantly from 36.8 (SD 0.1) °C to 36.7 (SD 0.2) °C at 90 min following the ingestion of the drug, whereas values during the placebo trial did not change. The lower T _re response during the melatonin trial remained during the first 50 min of exercise in the heat while wearing the protective clothing. Since the final mean T _re at the end of exercise also was significantly reduced for the melatonin [39.0 (SD 0.4) °C] compared with the placebo [mean 39.1 (SD 0.3) °C] trial, tolerance times approximated 95 min in both conditions. During rest at 40 °C, melatonin did not affect the mean T _re response which increased significantly during the last 90 min from 36.9 (SD 0.1) °C to 37.3 (SD 0.1) °C. This increase in T _re during the rest period prior to donning the protective clothing decreased tolerance time approximately 30 min compared with the trials that had involved rest at 23 °C. Total heat storage summated over the rest and exercise periods was not different among the trials at 15 kJ · kg⁻¹. It was concluded that the small decrease in T _re following the ingestion of 5 mg of melatonin at rest in a cool environment had no influence on subsequent tolerance during uncompensable heat stress. Accepted: 26 June 2000     

Endothelin has no positive inotropic effect in guinea-pig atria or papillary muscle

Endothelin is a recently discovered, highly potent vasoconstrictor peptide. In isolated atria from rat and guinea-pig, endothelin has been reported to elicit a positive inotropic effect. The purpose of the present study was to compare the effects of endothelin on electromechanical coupling in guinea-pig atrial and ventricular muscle. In isolated, electrically driven specimens of atria and papillary muscle, action potentials and isometric contractions were recorded in the basal state and 30 min following non-cumulative exposure to endothelin (100 nM). In the atria, endothelin reduced action potential overshoot and relaxation velocity, and increased resting tension. In the papillary muscle the peptide slightly shortened the duration of the action potential. Endothelin did not affect peak tension, either in the atria or in the papillary muscle. These data contrast with earlier reports on a positive inotropic effect of endothelin in guinea-pig atria.     

Melatonin has no effect on tolerance to uncompensable heat stress in man

This study examined whether a 5 mg dose of melatonin induced a lower rectal temperature (Tre) response at rest in both a cool and hot environment while wearing normal military combat clothing, and then examined the influence of this response on tolerance to exercise in the heat while wearing protective clothing. Nine men performed four randomly ordered trials involving 2 h of rest at ambient temperatures of either 23 degrees C or 40 degrees C followed by exercise at an ambient temperature of 40 degrees C. The double-blind ingestion of placebo or melatonin occurred after 30 min of rest. The mean Tre during rest at 23 degrees C had decreased significantly from 36.8 (SD 0.1) degrees C to 36.7 (SD 0.2) degrees C at 90 min following the ingestion of the drug, whereas values during the placebo trial did not change. The lower Tre response during the melatonin trial remained during the first 50 min of exercise in the heat while wearing the protective clothing. Since the final mean Tre at the end of exercise also was significantly reduced for the melatonin [39.0 (SD 0.4) degrees C] compared with the placebo [mean 39.1 (SD 0.3) degrees C] trial, tolerance times approximated 95 min in both conditions. During rest at 40 degrees C, melatonin did not affect the mean Tre response which increased significantly during the last 90 min from 36.9 (SD 0.1) degrees C to 37.3 (SD 0.1) degrees C. This increase in Tre during the rest period prior to donning the protective clothing decreased tolerance time approximately 30 min compared with the trials that had involved rest at 23 degrees C. Total heat storage summated over the rest and exercise periods was not different among the trials at 15 kJ x kg(-1). It was concluded that the small decrease in Tre following the ingestion of 5 mg of melatonin at rest in a cool environment had no influence on subsequent tolerance during uncompensable heat stress.     

Direction and amplitude precuing has no effect on automatic posture responses

Summary Automatic postural responses of leg muscles to the sudden displacement of standing support were investigated under four different conditions of information given to subjects in advance. Results from three groups of subjects were compared: 6 normal subjects, 10 patients with cerebellar disease, and 9 patients with Parkinson's disease. Specifically, each subject was provided with visual information about the direction and/or the amplitude of an upcoming platform tilt. For the control situation no advance information on the characteristics of platform tilt was provided. Neither the latencies nor the integrals of postural EMG-responses showed alterations with advance information. In contrast, in a control experiment in which 3 normal subjects had to perform large or small forward or backward voluntary movements of the body around the ankle joint, shorter onset-latencies of leg muscle EMG responses were observed with increasing complexity of the advance information. These results suggest that, unlike voluntary movements, postural responses to rapid surface tilts do not benefit from advance visual information on direction or amplitude of a postural disturbance.Supported by the Deutsche Forschungsgemeinschaft, SFB 307, A3     

Treatment with rIFN-gamma has no effect on cardiac allograft rejection.

The effect of recombinant rat interferon-gamma (rRIFN-gamma) on allograft rejection was studied in two rat heart transplantation models. Recipients were treated with rRIFN-gamma by intraperitoneal or intravenous injection, either by bolus or continuous infusion. Treatment was started after transplantation and continued during a period ranging from 4 to 10 days; dosages varied from 2.5 x 10(2) U/kg/day to 3 x 10(6) U/kg/day. Controls were infused with PBS. Treatment with rRIFN-gamma had no effect on allograft survival, irrespective of the route of administration, the dosage used or the duration of treatment. Higher dosages of rRIFN-gamma induced serious morbidity and mortality. In conclusion, systemic treatment of cardiac allograft recipients with rRIFN-gamma has no effect on graft rejection and is associated with serious toxicity and mortality when high dosages are used.     

Helicobacter pylori eradication has no effect on metabolic and inflammatory parameters

BACKGROUND: An increased risk in coronary heart disease associated with Helicobacter pylori (H. pylon) appears to be partially mediated by modifications of the atherogenic lipoprotein and inflammatory parameters. We conducted a controlled trial aimed at evaluating the changes of metabolic and inflammatory parameters after H. pylon eradication. METHODS: We included in the study 169 patients with H. pylori infection and conducted a retrospective longitudinal survey of 87 subjects (76 men, 11 women) who received treatment for H. pylon eradication and 82 control subjects (63 men, 19 women) who did not receive treatment. We compared pre- and posteradication (one year after) the metabolic and inflammatory parameters, such as blood sugar, lipid profiles, insulin resistance, white blood cell count and C-reactive protein. RESULTS: No significant changes from the baseline in metabolic and inflammatory parameters within each group were observed. Changes in the serum levels of metabolic and inflammatory parameters were similar between the two groups. CONCLUSIONS: Metabolic and inflammatory parameters, including blood sugar, lipid profiles, insulin resistance, white blood cell count and C-reactive protein, were not changed after H. pylori eradication treatment. H. pylori eradication has no effect on metabolic and inflammatory parameters.     

Effects of oral terbutaline in children with bronchial asthma

The cardiopulmonary effects of single oral doses of terbutaline were evaluated in children with chronic bronchial asthma. Fifteen children, 6 to 13 yr of age and weighing 22.3 to 51.8 kg, were treated with 1.25, 2.5, 3.75 and 5.0 mg of terbutaline using a double-blind crossover vs placebo design. Before treatment and at intervals up to 420 min following treatment, measurements were made of lung volumes, vital capacity, FEV 1, maximum expiratory flow volume curves, airway resistance (R_aw), and specific airway conductance (G_aw/V_L). Heart rate, systolic and diastolic blood pressures, and electrocardiograms were also obtained. The most consistent and sensitive indicators of pulmonary function were G_aw/V_L and FEV₁, both of which showed significant improvement after all doses, The peak improvement of these parameters was proportional to the dose of terbutaline. Cardiovascular effects of terbutaline consisted of small increases in systolic blood pressure or transient EKG changes and were clinically unimportant. Other side effects such as headache, tremor, dizziness, and nausea, although proportional to the dose of terbutaline, were mild and transient. The dose of 2.5 mg terbutaline produced the most improvement in pulmonary function in relation to the number of side effects.     

Dose, plasma concentration, and effect of oral terbutaline in long-term treatment of childhood asthma

Oral terbutaline in gradually increasing doses from 45 to 166 micrograms/kg three times daily was administered to asthmatic school children. There was a linear relationship between dose and steady-state plasma concentration of terbutaline within patients, but the plasma levels varied fourfold between patients taking similar doses. The consumption of beta 2-stimulants in aerosol form decreased, and the symptom score, peak expiratory flow rate, and FEV1 improved during treatment with a roughly linear dose-effect relationship. Significant increases in pulse rate and skeletal muscle tremor were also measurable. There was no clear correlation between plasma levels of terbutaline and reported side effects. Linear regression analysis revealed a statistically significant relationship between bronchodilatation and the same plasma level was considerable. Determination of the plasma terbutaline concentration therefore seems to be of limited value in clinical practice. Instead, the dose should be individualized on the basis of clinical effect and tolerance. Our data indicate that many young asthmatic children will tolerate and sometimes benefit from higher doses than are generally recommended if they are carefully titrated with stepwise increments.     

Route of nutrition has no effect on the development of infectious complications

BACKGROUND: Infection is a serious complication of nutritional support, causing a high rate of mortality and morbidity. Critically ill patients having nutritional support are prone to infectious complications. Questions regarding the effects of the route of nutrition in infectious complications have been asked. We aimed to determine the relationship between the route of nutrition and the risk of developing infectious complications in severely ill patients on nutritional support in an intensive care unit. METHODS: A retrospective review was performed on the files of 144 severely ill patients who had either enteral or parenteral nutrition during follow-up in an intensive care unit. The primary diagnoses of patients were heterogenous. RESULTS: Sixty-eight (35.8%) of them acquired novel infections during the hospitalization period. Forty-nine and 19 of the 68 infected patients had enteral and parenteral nutrition support, respectively. Seventy-six (40%) of the patients were free of infection. Fifty-one of 76 infection-free patients had enteral nutrition support, and 25 of them had parenteral nutrition support. Pulmonary infections, urinary tract infections, catheter infections and septicemia were the most frequent types of infectious complications. There was no significant difference in the rate of infectious complications between enteral nutrition and parenteral nutrition groups (p > 0.05). CONCLUSION: We conclude that the route of the nutritional support in severely ill patients having nutritional support in an intensive care unit does not affect the rate of infectious complications. We think that comorbid medical conditions and the need of intensive care unit support are more important parameters that determine the risk of development of infectious complications.     

Restraint stress has no effect on morphine-induced inhibition of gastrointestinal transit in the rat

Stress in the rat has been reported to enhance the analgesic and thermic effects of opioids, drug effects that are mediated centrally. We examined whether this stress-induced enhancement of response to opioids could also be demonstrated for a drug effect mediated largely in the periphery, morphine-induced inhibition of gastrointestinal transit. Restrained (stressed) and unrestrained (unstressed) rats were injected with saline or morphine and then administered orally a charcoal suspension; after sacrifice, the distance the charcoal traveled through the intestine was determined. After the administration of saline, restrained rats had significantly lower gastrointestinal transit than did unstressed rats; however, both groups were comparably sensitive to inhibition of gastrointestinal transit by morphine.     

Perfusion has no effect on the in vivo CEST effect from Cr (CrCEST) in skeletal muscle

Creatine, a key component of muscle energy metabolism, exhibits a chemical exchange saturation transfer (CEST) effect between its amine group and bulk water, which has been exploited to spatially and temporally map creatine changes in skeletal muscle before and after exercise. In addition, exercise leads to an increase in muscle perfusion. In this work, we determined the effects of perfused blood on the CEST effects from creatine in skeletal muscle. Experiments were performed on healthy human subjects (n = 5) on a whole‐body Siemens 7T magnetic resonance imaging (MRI) scanner with a 28‐channel radiofrequency (RF) coil. Reactive hyperemia, induced by inflation and subsequent deflation of a pressure cuff secured around the thigh, was used to increase tissue perfusion whilst maintaining the levels of creatine kinase metabolites. CEST, arterial spin labeling (ASL) and ³¹P MRS data were acquired at baseline and for 6 min after cuff deflation. Reactive hyperemia resulted in substantial increases in perfusion in human skeletal muscle of the lower leg as measured by the ASL mean percentage difference. However, no significant changes in CrCEST asymmetry (CrCEST_asym) or ³¹P MRS‐derived PCr levels of skeletal muscle were observed following cuff deflation. This work demonstrates that perfusion changes do not have a major confounding effect on CrCEST measurements.     

Aerosolized terbutaline in asthmatics: development of subsensitivity with long-term administration

The peak response and the duration of bronchodilator effect were measured after four inhalations at 20 min intervals of 250 μg of aerosolized terbutaline in 13 patients with bronchial asthma. Patients were initially studied after strict avoidance of all adrenergic agents for 2 wk; they were then studied at 2 wk intervals for 12 wk while receiving 500 μg of aerosolized terbutaline q.i.d. The initial testing (T_I) and the testing at the end of 12 wk (T_II) were double blind. Both peak response and duration of action decreased significantly between T_I and T_II. Cumulative dose-response curves showed that further improvement occurred after each inhalation during T_I but that there was significant improvement only after the first inhalation during T_II.