Cardiorespiratory kinetics and femoral artery blood velocity during dynamic knee extension exercise

The kinetics of femoral artery mean blood velocity (MBV; measured by pulsed Doppler) and whole body oxygen uptake (VO2; measured breath by breath) were assessed from the time constant during the on (tau on) and off (tau off) transients to step changes in work rate between complete rest and dynamic knee extension (KE) exercise. Six healthy men performed 5 min of seated KE exercise, with each leg alternately raising and lowering a weight (10% maximum voluntary contraction) over a 2-s duty cycle. Because kinetic analysis of VO2 kinetics during KE exercise is a new approach, the VO2 responses were also evaluated during the on and off transitions to the more familiar upright cycling exercise in which the magnitude of increase in VO2 and cardiac output was similar to that during KE exercise. During KE exercise, VO2 tau on [mean 72.2 +/- 11.2 (SE) s] was slower than VO2 tau off (33.3 +/- 1.8 s; P < 0.01). Cardiac output, measured with impedance cardiography, was not different for tau on (67.1 +/- 20.0 s) compared with that for tau off (52.9 +/- 7.6 s). Likewise, MBV tau on (34.5 +/- 3.9 s) was not different from tau off (35.3 +/- 3.2 s). During cycling, the VO2 tau on (18.0 +/- 2.4 s) and tau off (30.7 +/- 1.2 s) were both faster than KE VO2 tau on (P < 0.01). Even though the MBV kinetics indicated a rapid adaptation of blood flow during KE exercise, there was a slow adaptation of VO2. A transient hyperemia immediately on cessation of KE exercise, indicated by both MBV and calculated systemic vascular conductance responses, suggested that blood flow might have been inadequate and could have contributed to the delayed adaptation of VO2 at the onset of exercise, although other explanations are possible.     

Effect of alterations in blood volume on cardiac function during maximal exercise

Recently, we proposed that the higher stroke volume (SV) and cardiac output (Q) of endurance-trained (ETR) versus untrained (UTR) individuals are attributable primarily to the enhanced diastolic filling of ETR consequent to a larger blood volume (BV). To test this hypothesis, we examined the effects of manipulating BV on the cardiac function of six ETR and six UTR males. Both groups were examined in the control BV condition (BVctl), then ETR were examined immediately following a 500 mL reduction in BV (BVred) and UTR were examined immediately following a 500 mL expansion of BV (BVexp). In BVctl, compared with UTR, ETR had significantly greater BV (16%), maximal diastolic filling rate (47.4%), maximal ventricular emptying rate (24.6%), SVmax (31.6%), Qmax (29%) and VO2max (54.5%). Following BVexp in UTR, there were immediate significant increases in maximal diastolic filling rate (22.5%), SVmax (9.1%), Qmax (8.9%), and VO2max (12.7%). Following BVred in ETR there were immediate significant decreases in maximal diastolic filling rate (27%), SVmax (14.3%), Qmax (14.7%), and VO2max (7.0%). Maximal systolic emptying rate did not change significantly following BVred or BVexp. We conclude that changes in SV and Q consequent to alterations in BV are attributable primarily to changes in diastolic function, and the majority of the higher diastolic filling rate of ETR is due to their larger BV.     

Effect of NaHCO3 on lactate kinetics in forearm muscles during leg exercise in man

We investigated NaHCO3 infusion effects on plasma lactate removal by forearm muscles and performance during intensive leg exercise. Seven subjects performed the force-velocity (FV) test with placebo and NaHCO3 (2 mEq.min-1) with a double-blind crossover protocol. Blood samples for arterial ([LA]A) and venous ([LA]V) lactate determinations were taken 1) at rest before infusion, and 2, 6, 10, 14, 18, and 22 min following its start; and 2) at the end of each exercise bout. The arteriovenous difference ([LA]A-V) was determined for each sampling. NaHCO3 significantly increased arterial bicarbonate concentration and pH during rest (P < 0.001; P < 0.001) and the FV test (P < 0.001; P < 0.05). During the test, [LA]A and [LA]V were significantly higher with NaHCO3 (P < 0.05, P < 0.001). At test onset, [LA]A-V became positive and increased until the braking force of 6 kg, with NaHCO3 and placebo, with values significantly lower for NaHCO3 (P < 0.001). Peak anaerobic power (Wanae, peak) and the corresponding braking force (Fmax) were also determined. Fmax was significantly increased with NaHCO3 (P < 0.001). In conclusion, the increasing rise in [LA]A and [LA]V induced by NaHCO3 may be partly explained by a decreased rate of lactate uptake by forearm skeletal muscles. NaHCO3 did not improve Wanae, peak, but improved Fmax, thus increasing FV duration.     

Effect of exercise on acid-base status and ventilatory kinetics

OBJECTIVES: To study the clinical spectrum of an acute severe encephalopathy occurring in 2 patients after recovery from falciparum malaria infection and to compare it with the reported clinical features of the postmalaria neurological syndrome. DESIGN: Case report. SETTING: Tertiary care hospital. PATIENTS: Two patients presented with acute onset of fluctuating motor aphasia, severe generalized myoclonus, and postural tremor. Additional signs were cerebellar ataxia, and in 1 patient, generalized epileptic seizures. Magnetic resonance imaging of the brain revealed patchy white matter lesions in 1 patient. Clinically, the patients' conditions continued to worsen until corticosteroids were introduced, the use of which induced a rapid, albeit incomplete, recovery. CONCLUSIONS: We describe a new, severe variant of the still poorly defined postmalaria neurological syndrome. We propose a preliminary classification of this syndrome, according to its clinical characteristics, as follows: a mild or localized form, characterized by isolated cerebellar ataxia or postural tremor; a diffuse, but relatively mild encephalopathic form, characterized by acute confusion or epileptic seizures; and a severe, corticosteroid-responsive encephalopathy that is characterized by motor aphasia, generalized myoclonus, postural tremor, and cerebellar ataxia.     

Glucose kinetics during exercise in trained men

The effects of a novel bradycardic agent Zeneca ZM 227189 (4-(N-ethyl-N-phenylamino)-1,2-dimethyl-6-(methylamino) triazinium iodide) were tested on the inward rectifying properties of guinea-pig substantia nigra pas compacta (SNC) and guinea-pig olfactory cortical cells recorded in vitro. In SNC neurones, ZM 227189 (10-100 microM) produced a dose-dependent block of the slow anomalous rectifier; under voltage clamp, a clear reduction was seen in the amplitude of the slow inward current (Ih) relaxation evoked by negative voltage commands from a holding potential of -60 mV. ZM 227189 (50-100 microM) induced an irreversible block of the Ih current after 10-15 min exposure. A similar block of Ih was observed following application of 5 mM Cs+. ZM 227189 had little effect on other membrane properties. By contrast, in olfactory cortical neurones, ZM 227189 (100 microM) induced an increase in the input resistance (approximately 20%) and cell excitability, accompanied by a small (< 2 mV) hyperpolarization; these effects were also not reversible. Activation of the fast (K(+)-mediated) inward rectifier at negative membrane potentials remained unaffected. Lower concentrations (1-10 microM) of ZM 227189 had no obvious effect on cortical cell properties. Our data indicate that ZM 227189 is a potent and apparently selective blocker of Ih in substantia nigra neurones, but has no effect on the fast-type inward rectifier in olfactory cortical cells.     

Effects of emphysema on diaphragm blood flow during exercise

Pseudomonas flavescens strain B62 (NCPPB 3063) is a recently described bacterium isolated from walnut blight cankers. This strain has been designated as the type strain of a Pseudomonas rRNA group-I species. Strain B62 produced a mixture of two exopolysaccharides, differing in weight average relative molecular mass and composition. Only the most abundant exopolysaccharide (90% by mass), corresponding to the one with the lower molecular mass, was investigated by use of methylation analysis, partial acid hydrolysis, and NMR spectroscopy. The polysaccharide was depolymerised by the action of the cellulase produced by Penicillum funiculosum and the oligosaccharide obtained, corresponding to the repeating unit, was characterised by NMR spectroscopy and ion-spray mass spectrometry. The repeating unit of the B62 exopolysaccharide is [structure in text] where X is glucose (75%) or mannose (25%), and Lac is lactate. The O-acetyl groups are present only on 75% of the repeating units, and they are linked to the C6 of the hexose residues in non-stoichiometric amounts.     

Effect of aluminum phosphide on blood glucose level

STUDY OBJECTIVES: This study examines the accuracy of recalled gestational weight gain and maximum weight gain during pregnancy and evaluates which factors have an impact on those estimates. DESIGN: Cross-sectional survey. SETTING: Adolescent pregnancy clinic in an urban hospital. SUBJECTS: Forty postpartum adolescents were recruited. Half the subjects were evaluated within 6 months postpartum, and half were seen over the next 9 months. MAIN OUTCOME MEASURES: Months postpartum, intrapartum weight gain documented in chart, maximum weight documented in chart, recalled intrapartum weight gain, recalled maximum weight; differences between chart-documented and recalled weight gain and maximum weight. RESULTS: Self-documented and documented weight gain and maximum intrapartum weights were highly correlated (Pearson r = .99), although those at highest weight tended to underestimate their weight gain and maximum weight. CONCLUSIONS: Adolescents are able to reliably recall weight gain and maximum weight during pregnancy.     

Effects of prior arm exercise on pulmonary gas exchange kinetics during high-intensity leg exercise in humans

The activation of MAPKs is controlled by the balance between MAPK kinase and MAPK phosphatase activities. The latter is mediated by a subset of phosphatases with dual specificity (VH-1 family). Here, we describe a new member of this family encoded by the puckered gene of Drosophila. Mutations in this gene lead to cytoskeletal defects that result in a failure in dorsal closure related to those associated with mutations in basket, the Drosophila JNK homolog. We show that puckered mutations result in the hyperactivation of DJNK, and that overexpression of puc mimics basket mutant phenotypes. We also show that puckered expression is itself a consequence of the activity of the JNK pathway and that during dorsal closure, JNK signaling has a dual role: to activate an effector, encoded by decapentaplegic, and an element of negative feedback regulation encoded by puckered.     

Effect of tryptophan and of glucose on exercise capacity of horses

A method based on discounted income and risk assessment was developed to aid in the selection of dairy sires. The discounted profit generated from milk production of daughters was proposed as the suitable composite selection criterion to combine estimates of predicted transmitting ability (PTA) for yields of milk, fat, and protein and estimates of sire evaluations for dystocia or expected progeny difference. Steps are described to derive discounted profit (defined as expected income) for a sire with known PTA and evaluation for dystocia. The derivation of profit considered costs for semen, dystocia, heifer raising, production and maintenance of the daughter, and income from milk. Variance of income from a sire depended on the reliability of his PTA and evaluation for dystocia. Total variance from a selected set of sires was defined as the risk. A quadratic programming procedure was developed to identify the best set of sires from a given pool of sires that met a desired expected income goal with minimum risk. Combinations of sires with minimum risk for all possible levels of expected income were defined by the expected income variance frontier. The set of sires at the maximum lower boundary for 95% confidence of the expected income variance frontier was defined as the optimum set of sires to be selected; the optimum set maximized the 95% guaranteed expected income. The quadratic programming procedure provided the optimum percentage of cows to be mated to each sire in the selected set.     

Effect of duodenal glucose infusion on blood glucose concentration in endotoxin-treated calves

The effect of endotoxemia on the intestinal absorption of glucose was evaluated in nine experiments performed on seven 3- to 5-week-old calves fitted with a duodenal cannula. An intraduodenal glucose load trial (infusion of 2 g glucose/kg b.w. as a 10% aqueous solution through the cannula over 60 min) was conducted in a group of 5 calves three times during the 4-day period: 48 h before and at 2 and 24 h after i.v. injection of E. coli 0111:B4 endotoxin (LPS) at a dose of 0.1 microgram/kg b.w. Control calves were treated similarly but instead of glucose they were infused intraduodenally with deionised water at a volume of 20 ml/kg b.w. In trial with glucose load performed 48 h before LPS administration, blood glucose concentration increased during the absorptive phase from 4.32 +/- 0.32 mmol/l to 11.45 +/- 0.87 mmol/l at 60 min and then decreased to a minimum value of 3.16 +/- 0.51 mmol/l at 240 min. During the initial phase of endotoxemia, blood glucose concentration did not change from baseline values in both groups of calves. Glucose concentration in control calves started to decrease at 165 min reaching a minimum value of 1.39 +/- 0.17 mmol/l at 210 min and then increased to 2.44 +/- 0.11 mmol/l at 480 min after LPS administration. The intraduodenal infusion of glucose at 2 h after LPS administration resulted in an increase in blood glucose concentration during the absorptive phase only in one calf. Blood glucose concentration in this calf increased between 30 and 90 min reaching a maximum value of 7.19 mmol/l at 60 min, and then decreased to a minimal value of 0.94 mmol/l at 180 min after glucose load. In the remaining four calves in this group, blood glucose concentration ranged from 3.89 +/- 0.37 mmol/l to 4.48 +/- 0.45 mmol/l up to 120 min, and then steadily decreased to a minimal value of 2.41 +/- 0.41 mmol/l at 300 min. In trial with glucose load performed 24 h after LPS administration, the rate of entry of glucose into the circulation during the absorptive phase was similar to that observed in the trial performed 48 h before LPS administration. In conclusion, these results indicate that endotoxemia impairs the intestinal absorption of glucose in calves. The magnitude of the absorption disturbance may vary in individual calves, and the inhibitory effect of LPS on the intestinal glucose absorption lasts less than 24 h.     

Effect of theophylline on substrate metabolism during exercise

We tested the hypothesis that adenosine is involved in regulating substrate metabolism during exercise. Seven trained cyclists were studied during 30 minutes of exercise at approximately 75% maximal oxygen uptake (VO2max). Lipid metabolism was evaluated by infusing [2H5]glycerol and [1-13C]palmitate, and glucose kinetics were evaluated by infusing [6,6-2H]glucose. Fat and carbohydrate oxidation were also measured by indirect calorimetry. The same subjects performed two identical exercise tests, but in one trial theophylline, a potent adenosine receptor antagonist, was infused for 1 hour before and throughout exercise. Theophylline did not increase whole-body lipolysis (glycerol rate of appearance [Ra]) or free fatty acid (FFA) release during exercise, but fat oxidation was lower than control values (9.5 +/- 3.0 v 18.0 +/- 4.2 micromol x min(-1) x kg(-1), P < .01). Glucose Ra was not affected by theophylline infusion, but glucose uptake was lower (31.6 +/- 4.1 v 40.4 +/- 5.0 micromol x min(-1) x kg(-1), P < .05) and glucose concentration was higher (6.4 +/- 0.6 v 5.8 +/- 0.4 mmol/L, P < .05) than in the control trial. Total carbohydrate oxidation (302.3 +/- 26.2 v 265.5 +/- 11.7 micromol x min(-1) x kg(-1), P < .06), estimated muscle glycogenolysis (270.7 +/- 23.1 v 225.1 +/- 9.7 micromol x min(-1) x kg(-1), P < .05), and plasma lactate concentration (7.9 +/- 1.6 v 5.9 +/- 1.1 mmol/L, P < .001) were also higher during the theophylline trial. These data suggest that adenosine may play a role in stimulating glucose uptake and restraining glycogenolysis but not in limiting lipolysis during exercise.     

Effect of dietary fat reduction and increased aerobic exercise on cardiovascular risk factors

1. The combined effect of dietary fat reduction and increased aerobic exercise on coronary heart disease (CHD) risk factors was investigated in healthy, normolipidaemic, normotensive, sedentary individuals. 2. After a baseline period of 2 weeks, 21 subjects were randomly allocated to one of two intervention groups (low fat exercise (LFEX) or low fat control (LFC)) for 8 weeks. Both groups were counselled to reduce their dietary fat intake to 20-25% energy from fat. The LFEX group was also required to commence an aerobic exercise programme (4 x 45 min per week). 3. In both groups, the falls in total cholesterol seen at week 4 were not maintained at the end of the study; however, the LFEX group maintained a fall in low-density lipoprotein (LDL) of 0.21 +/- 0.11 mmol/L. At the end of the study, the LFC group experienced a fall in high-density lipoprotein (HDL)-cholesterol of 0.16 +/- 0.05 mmol/L, due to a 0.19 +/- 0.07 mmol/L fall in the HDL2 subfraction. The LFEX group experienced no change in HDL (-0.09 +/- 0.06 mmol/L) or HDL2 (-0.09 +/- 0.05 mmol/L). 4. At the end of the study the LFEX and LFC groups experienced a 7 +/- 3 and 5 +/- 1 mmHg fall in systolic blood pressure, respectively, while the LFEX group also observed a 4 +/- 2 mmHg fall in diastolic blood pressure. 5. The benefits of a low-fat diet combined with aerobic exercise include a reduction in LDL and blood pressure, while maintaining HDL through the HDL2 subfraction.     

Effect of parasympathetic denervation of liver and pancreas on glucose kinetics in man

The study aim was to investigate the role of the parasympathetic nervous system in the control of glucose tolerance in man. Glucose kinetics were determined during an oral glucose tolerance test (OGTT) in six subjects with truncal vagotomies and six control subjects. Basal plasma glucose levels in the two groups were equal; however, 20 to 40 minutes after the OGTT, glucose was higher in vagotomized compared with control subjects (P < .02). There were no differences in insulin levels between the subjects. Glucagon decreased after the OGTT in the controls, whereas in the vagotomized subjects it increased transiently and did not decrease beyond basal levels. There was no difference in basal hepatic glucose production, but suppression was greater in controls in the first 10 minutes (P < .01). Gut-derived glucose appearance increased faster and to a higher level (56.0 +/- 8 v 29.7 +/- 2.9 mumol/kg/min, P < .02) in vagotomized subjects. There were no differences in the metabolic clearance rate of glucose between the two groups. It is concluded that parasympathetic innervation of the pancreas is essential for suppression of glucagon secretion during hyperglycemia. However, abnormal glucose tolerance in vagotomized subjects is primarily due to rapid gut glucose absorption, with the denervated parasympathetic system playing only a minor role.     

Capillary blood lactate concentrations during intermittent all-out exercise

Struma has called for treatment very early in medical history due to its appearance. At the beginning of our calendar, the physicians dealt with this problem already. This paper gives a historical review about the surgical treatment of struma.     

Lactate distribution in the blood during steady-state exercise

PURPOSE: The purpose of this investigation was to examine the plasma to red blood cell (RBC) lactate concentration ([La]) gradient and RBC:plasma [La] ratio during 30 min of steady-state cycle ergometer exercise at work rates below lactate threshold ( LT. Blood samples were taken from a heated forearm vein, immediately cooled to 4 degrees C in a dry-ice ethanol slurry, and centrifuged at 4 degrees C to separate plasma and RBCs. RESULTS: During >LT, plasma [La] rose to 8.8+/-1.1 mM after 10 min and remained above 6 mM. RBC [La] (4.9+/-0.7 mM) was significantly lower than plasma [La] at 10 min and remained lower throughout exercise. As a result, there was a sizable [La] gradient (approximately 3.5 mM) from plasma to RBC during most of >LT. In LT, the ratio of RBC [La]:plasma [La] was the same for both (0.58+/-0.02) and not significantly different from rest. CONCLUSIONS: These results refuted our hypothesis that the RBC:plasma [La] ratio would decrease at the onset of >LT exercise because of muscle lactate release exceeding the ability of RBCs to take up the lactate. Instead, there appears to be an equilibrium between plasma [La] and RBC [La] in arterialized venous blood from a resting muscle group as evidenced by the constant RBC [La]:plasma [La] ratio.