Cycling for Weight Loss May Clear Carbohydrates Rather Than Fat, Irrespective of Normal or Mildly Reduced Normobaric Oxygen

A single-center randomized, controlled cross-over exercise intervention in 20 women willing to reduce weight (20–40 y, BMI: 27.4 ± 2.1), with the aim to examine potential benefits for weight loss under normal (N-Ox: 20.9%) and mildly reduced (R-Ox: 17.0%) normobaric oxygen in an “Altitude Simulation Chamber”. O2 consumption (VO2), CO2 production (VCO2), blood oxygen saturation (SaO2), blood glucose and lactate (mM) were studied before, during and after cycling for 22 min at a mean personalized workload of 54.2 ± 11.7 watts, about 40% of VO2max. Despite lower absolute SaO2 values and a greater decline from rest to exercise under R-Ox (time x treatment interaction p VO2 did not differ from N-Ox (time x treatment interaction p = 0.178). Average net VO2, 13.8 mL O2 per watt, reflected fairly normal aerobic cycling, irrespective of O2 regime. The Respiratory Exchange Ratio (RER; VO2/VCO2), 0.83 at rest, increased for both treatments to a ratio close to or beyond unity during and directly after exercise (treatment effect p = 0.407). The tendency of cycling for weight loss to clear carbohydrates rather than fat, irrespective of normal or mildly reduced normobaric oxygen, is discussed as a lactate-mediated and phenotype-specific consequence of apparent anaerobic glycolysis with adverse perspectives for weight loss and metabolic health

Reviewing the low efficiency of protein utilization in heavy preruminant calves – a reductionist approach

The efficiency of protein utilization for growth in preruminant calves is decreasing with increasing body weight. In contrast to calves weighing less than 100 kg of body weight, heavy preruminant calves do not respond in protein retention to an increased intake of indispensable amino acids in dose-response studies. The marginal efficiency of protein utilization is low compared with pigs and milk-fed lambs at a similar stage of maturity. A reductionist approach was taken to perceive the potential mechanisms for the low protein utilization in preruminant calves. Neither an imbalance in the dietary protein to energy ratio nor a single limiting indispensable amino acid was responsible for the low efficiency. Also, amino acids were not specifically used to detoxify ammonia. Alternative hypotheses to explain the low efficiency are discussed and result in (i) a reduced post-absorptive supply of amino acids: e.g. by fermentation of milk in the (premature) rumen or preferential amino acid utilization by specific tissues; or (ii) a reduced post-absorptive amino acid utilization: e.g. by decreased insulin sensitivity, utilization of amino acids for gluconeogenesis or an asynchronous nutrient supply. In conclusion, several mechanisms for the low efficiency of protein utilization in heavy preruminant calves were excluded. Other physiological processes which are potentially involved remain to be studied, because the large potential for improving protein utilization in heavy preruminant calves asks for further exploration of their amino acid metabolism

High environmental temperature increases glucose requirement in the developing chicken embryo.

Environmental conditions during the perinatal period influence metabolic and developmental processes in mammals and avian species, which could impact pre- and postnatal survival and development. The current study investigated the effect of eggshell temperature (EST) on glucose metabolism in broiler chicken embryos. Broiler eggs were incubated at a high (38.9°C) or normal (37.8°C) EST from day 10.5 of incubation onward and were injected with a bolus of [U-(13)C]glucose in the chorio-allantoic fluid at day 17.5 of incubation. After [U-(13)C]glucose administration, (13)C enrichment was determined in intermediate pools and end-products of glucose metabolism. Oxidation of labeled glucose occurred for approximately 3 days after injection. Glucose oxidation was higher in the high than in the normal EST treatment from day 17.6 until 17.8 of incubation. The overall recovery of (13)CO2 tended to be 4.7% higher in the high than in the normal EST treatment. An increase in EST (38.9°C vs 37.8°C) increased (13)C enrichment in plasma lactate at day 17.8 of incubation and (13)C in hepatic glycogen at day 18.8 of incubation. Furthermore, high compared to normal EST resulted in a lower yolk-free body mass at day 20.9 (-2.74 g) and 21.7 (-3.81 g) of incubation, a lower hepatic glycogen concentration at day 18.2 (-4.37 mg/g) and 18.8 (-4.59 mg/g) of incubation, and a higher plasma uric acid concentration (+2.8 mg/mL/+43%) at day 21.6 of incubation. These results indicate that the glucose oxidation pattern is relatively slow, but the intensity increased consistently with an increase in developmental stage of the embryo. High environmental temperatures in the perinatal period of chicken embryos increased glucose oxidation and decreased hepatic glycogen prior to the hatching process. This may limit glucose availability for successful hatching and could impact body development, probably by increased gluconeogenesis from glucogenic amino acids to allow anaerobic glycolysis

Characteristics of insulin resistant (IR) vs. moderately insulin sensitive (MIS) veal calves.

<p>Characteristics of insulin resistant (IR) vs. moderately insulin sensitive (MIS) veal calves.</p

Embryo and chicken yolk-free body mass during incubation at two different eggshell temperatures (study III).

<p>Yolk-free body mass of embryos incubated at a normal (37.8°C) or high (38.9°C) eggshell temperature (EST) from day 10.5 of incubation onward. *Significant difference between EST treatments (<i>P</i><0.05). At day 17.5, 17.8, 18.2, and 18.9 of incubation, no chickens were hatched yet. At day 19.7 of incubation, 22% of the chickens of the high EST treatment and 10% of the chickens of the normal EST treatment were hatched. At day 20.4 of incubation, 80% of the chickens of the high EST treatment were hatched and all chickens of the normal EST treatment were hatched. At day 20.9 and 21.6 of incubation, all chickens had been hatched.</p

¹³C enrichment in plasma glucose of embryos incubated at two different eggshell temperatures (study III).

<p>¹³C enrichment in plasma glucose after injecting a single bolus of [U-¹³C]glucose (1.0 mg in 250 µL sterile water) at day 17.5 of incubation in the chorio-allantoic fluid of embryos incubated at a normal (37.8°C) or high (38.9°C) eggshell temperature (EST) from day 10.5 of incubation onward. At day 17.5, 17.8, 18.2, and 18.9 of incubation, no chickens were hatched yet. At day 19.7 of incubation, 22% of the chickens of the high EST treatment and 10% of the chickens of the normal EST treatment were hatched. At day 20.4 of incubation, 80% of the chickens of the high EST treatment were hatched and all chickens of the normal EST treatment were hatched. At day 20.9 and 21.6 of incubation, all chickens had been hatched.</p