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The unique teleost oxygenation system that permits enhanced oxygen unloading during stress comprises three main characteristics: pH-sensitive haemoglobin, red blood cell (RBC) intracellular pH (pHi) protection, and a heterogeneous distribution of plasma-accessible carbonic anhydrase (paCA). A heterogeneous distribution of paCA is essential; its presence permits enhanced oxygen unloading during stress, while its absence at the gills maintains conditions for oxygen uptake by pH-sensitive haemoglobins. We hypothesised that paCA would be absent in all four gill arches, as has been previously indicated for arch two, and that paCA would be present in all other tissues. Through a suite of biochemical and molecular methods, we confirmed the absence of paCA from all four arches. We also found evidence for paCA in nine other tissues and a lack of paCA availability in the stomach. Expression was highly variable between tissues and suggests these differences may be associated with their respective metabolic activities. Additionally, we analysed the specific CA-IV isoform expressed within each tissue and showed almost complete separation of expression between tissues; CA-IVa was detected in the heart, brain, anterior intestine, and liver, whereas CA-IVb was detected in all intestine sections, pyloric caeca, kidney, and white muscle. This adds to a growing collection of work suggesting CA-IVa and b play divergent roles in gas exchange and ion/acid-base balance, respectively. The current study represents the first comprehensive atlas of paCA availability within the circulatory system of the model teleost, rainbow trout, and fills important gaps in our knowledge of this unique oxygenation system., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

After a short historical account, and a discussion of Hill and Meyerhof's theory of the energetics of muscular exercise, we analyse steady-state rest and exercise as the condition wherein coupling of respiration to metabolism is most perfect. The quantitative relationships show that the homeostatic equilibrium, centred around arterial pH of 7.4 and arterial carbon dioxide partial pressure of 40 mmHg, is attained when the ratio of alveolar ventilation to carbon dioxide flow ([Formula: see text]) is - 21.6. Several combinations, exploited during exercise, of pertinent respiratory variables are compatible with this equilibrium, allowing adjustment of oxygen flow to oxygen demand without its alteration. During exercise transients, the balance is broken, but the coupling of respiration to metabolism is preserved when, as during moderate exercise, the respiratory system responds faster than the metabolic pathways. At higher exercise intensities, early blood lactate accumulation suggests that the coupling of respiration to metabolism is transiently broken, to be re-established when, at steady state, blood lactate stabilizes at higher levels than resting. In the severe exercise domain, coupling cannot be re-established, so that anaerobic lactic metabolism also contributes to sustain energy demand, lactate concentration goes up and arterial pH falls continuously. The [Formula: see text] decreases below - 21.6, because of ensuing hyperventilation, while lactate keeps being accumulated, so that exercise is rapidly interrupted. The most extreme rupture of the homeostatic equilibrium occurs during breath-holding, because oxygen flow from ambient air to mitochondria is interrupted. No coupling at all is possible between respiration and metabolism in this case., (© 2022. The Author(s).)

Background: Primitive electronic waste (e-waste) recycling is ongoing in Guiyu, so toxic heavy metals may continue to threaten the health of children in the area., Objective: This study primarily aimed to evaluate the effect of e-waste exposure on haemoglobin (Hb) synthesis in preschool children., Methods: Medical examinations were conducted with the permission of children's guardians and the approval of the Ethics Committee of the Medical College of Shantou University. This study recruited 224 children (aged 3-6 years, exposed group) who lived in Guiyu and 204 children (aged 3-6 years, control group) who lived in a town free of e-waste pollution. Blood levels of lead, Hb, ferritin, folate and vitamin B 12 were tested in all children. Furthermore, all children were assessed for thalassemia, and their parents were asked to fill in questionnaires., Results: There were no significant differences in the level of ferritin, folate, or vitamin B 12 between the exposed and control groups (P > 0.05). No children were identified as having thalassemia in all study participants. Blood lead level (BLL) and the risk of children with BLL ≥ 10 µg/dL in the exposed group were significantly higher than those in the control group (all P < 0.01). Three subgroups of each group were created according to BLL (Group A: < 5.0 µg/dL; Group B: 5.0-9.9 µg/dL; Group C: ≥ 10.0 µg/dL). Hb level decreased with elevated BLL in the exposed group (P = 0.03), but not in the control group (P = 0.14). Hb levels in group B and group C were also significantly lower in the exposed group than in the control group (Group B: 122.6 ± 9.5 g/L versus 125.8 ± 8.2 g/L, P = 0.01; Group C: 120.3 ± 7.3 g/L versus 123.6 ± 8.3 g/L, P = 0.03). In addition, the prevalence of anaemia associated with BLLs above 10 µg/dL and between 5.0 and 9.9 µg/dL were both significantly higher in the exposed group than in the control group (4.0% vs. 0.5%, 5.4% vs. 1.5%, respectively, both P < 0.05)., Conclusion: Lead exposure more significantly inhibits Hb synthesis in children who live in e-waste dismantling areas than in those who live in non-e-waste dismantling areas. Other toxins released from e-waste may also contribute to the inhibition of Hb synthesis and may lead to anaemia in local children. Further investigations are needed to provide evidence for the development of relevant protective measures.

Purpose: Aerobic exercise capacity is reduced in patients with chronic kidney disease, partly due to alterations at the muscular and microvascular level. This study evaluated oxygen uptake (VO 2 ) kinetics as indicator of muscular oxidative metabolism in a population of Kidney Transplant Recipients (KTRs)., Methods: Two groups of KTRs enrolled 3 (n = 21) and 12 months (n = 14) after transplantation and a control group of healthy young adults (n = 16) underwent cardiopulmonary exercise testing on cycle-ergometer. The protocol consisted in two subsequent constant, moderate-load exercise phases with a final incremental test until exhaustion., Results: The time constant of VO 2 kinetics was slower in KTRs at 3 and 12 months after transplantation compared to controls (50.4 ± 13.1 s and 43.8 ± 11.6 s vs 28.9 ± 8.4 s, respectively; P < 0.01). Peak VO 2 was lower in KTRs evaluated 3 months after transplantation compared to patients evaluated after 1 year (21.3 ± 4.3 and 26.4 ± 8.0 mL/kg/min; P = 0.04). Blood haemoglobin (Hb) concentration was higher in KTRs evaluated at 12 months (12.8 ± 1.7 vs 14.6 ± 1.7 g/dL; P < 0.01). Among KTRs, τ showed a moderate negative correlation with Peak VO 2 (ρ = - 0.52) and Oxygen uptake efficiency slope (OUES) (r = - 0.57) while no significant correlation with Hb and peak heart rate., Conclusions: KTRs show slower VO 2 kinetics compared to healthy controls. Hb and peak VO 2 seem to improve during the first year after transplantation. VO 2 kinetics were significantly associated with indices of cardiorespiratory fitness, but less with central determinants of aerobic capacity, thus suggesting a potential usefulness of adding this index of muscular oxidative metabolism to functional evaluation in KTRs.

Purpose: This study examined the influence of dynamic apnoea training on splenic volume and haematological responses in non-breath-hold divers (BHD)., Methods: Eight non-BHD performed ten maximal dynamic apnoeas, four times a week for  six weeks. Splenic volumes were assessed ultrasonically, and blood samples were drawn for full blood count analysis, erythropoietin, iron, ferritin, albumin, protein and osmolality at baseline, 24 h post the completion of each week's training sessions and seven days post the completion of the training programme. Additionally, blood samples were drawn for haematology at 30, 90, and 180 min post session one, twelve and twenty-four., Results: Erythropoietin was only higher than baseline (6.62 ± 3.03 mlU/mL) post session one, at 90 (9.20 ± 1.88 mlU/mL, p = 0.048) and 180 min (9.04 ± 2.35 mlU/mL, p = 0.046). Iron increased from baseline (18 ± 3 µmol/L) post week five (23 ± 2 µmol/L, p = 0.033) and six (21 ± 6 µmol/L; p = 0.041), whereas ferritin was observed to be lower than baseline (111 ± 82 µg/L) post week five (95 ± 75 µg/L; p = 0.016), six (84 ± 74 µg/L; p = 0.012) and one week post-training (81 ± 63 µg/L; p = 0.008). Reticulocytes increased from baseline (57 ± 12 × 10 9 /L) post week one (72 ± 17 × 10 9 /L, p = 0.037) and six (71 ± 17 × 10 9 /L, p = 0.021) while no changes were recorded in erythrocytes (p = 0.336), haemoglobin (p = 0.124) and splenic volumes (p = 0.357)., Conclusions: Six weeks of dynamic apnoeic training increase reticulocytes without altering mature erythrocyte concentration and splenic volume.

Purpose: The aim of the study was to provide an evaluation of the oxygen transport, exchange and storage capacity of elite breath-hold divers (EBHD) compared with non-divers (ND)., Methods: Twenty-one healthy males' (11 EBHD; 10 ND) resting splenic volumes were assessed by ultrasound and venous blood drawn for full blood count analysis. Percutaneous skeletal muscle biopsies were obtained from the m. vastus lateralis to measure capillarisation, and fibre type-specific localisation and distribution of myoglobin and mitochondrial content using quantitative immunofluorescence microscopy., Results: Splenic volume was not different between groups. Reticulocytes, red blood cells and haemoglobin concentrations were higher (+ 24%, p < 0.05; + 9%, p < 0.05; + 3%, p < 0.05; respectively) and mean cell volume was lower (- 6.5%, p < 0.05) in the EBHD compared with ND. Haematocrit was not different between groups. Capillary density was greater (+ 19%; p < 0.05) in the EBHD. The diffusion distance (R 95 ) was lower in type I versus type II fibres for both groups (EBHD, p < 0.01; ND, p < 0.001), with a lower R 95 for type I fibres in the EBHD versus ND (- 13%, p < 0.05). Myoglobin content was higher in type I than type II fibres in EBHD (+ 27%; p < 0.01) and higher in the type I fibres of EBHD than ND (+ 27%; p < 0.05). No fibre type differences in myoglobin content were observed in ND. Mitochondrial content was higher in type I than type II fibres in EBHD (+ 35%; p < 0.05), with no fibre type differences in ND or between groups., Conclusions: In conclusion, EBDH demonstrate enhanced oxygen storage in both blood and skeletal muscle and a more efficient oxygen exchange capacity between blood and skeletal muscle versus ND.

The chemical structure of vitamin D resembles steroids and anabolics. Following activation by enzymatic hydroxylation, vitamin D enhances numerous body functions. We determined 25-hydroxy-vitamin D, number of erythrocytes, haematocrit, mean corpuscular haemoglobin and mean corpuscular volume in 97 patients with multiple sclerosis initially and 6 months later. Patients with deficient levels of 25-hydroxyvitamin D (< 30 ng/mL) were advised to perform vitamin D supplementation and received a prescription of a vitamin D formulation. Six months later we observed a rise of 25-OH-vitamin D, as to be expected, and a modified constellation of blood parameters such as elevation of mean corpuscular haemoglobin concentration and fall of mean corpuscular volume. Mean corpuscular haemoglobin and number of erythrocytes remained stable. The haematocrit went down. We suggest that vitamin D elevation may be beneficial in disorders characterised by chronic neuroinflammation and neurodegeneration, since changes of blood perfusion parameters may enhance cellular tissue oxygenation.