Analysis of Erythrocyte Parameters in Multiple and Long-Term Blood Donors from Northern Pomerania (Poland).

BACKGROUND/AIMS: Assessment of the levels of vital blood parameters in donors is essential to evaluate their health status, ensure their suitability for donation, preserve the integrity of the circulatory system, and facilitate comprehensive health monitoring. The aim of our study was to analyse the levels of haemoglobin, haematocrit, erythrocyte count, MCV, MCH, and MCHC in 12 groups of first-time donors and experienced donors of both sexes at the John Paul II Regional Blood Donation and Treatment Centre in Slupsk, northern Poland. The donors were divided into three age groups (18-30 years, 31-45 years, and 46-65 years). METHODS: Using MANOVA multivariate significance tests, we examined the main effects of donor-related factors (age, sex, donor stage) on morphological blood parameters to evaluate different haematological parameters, such as Hb, Ht, RBC, MCV, MCH, and MCHC, and identified statistically significant relationships between all variables. RESULTS: The multivariate analysis of these three main factors showed that the variation in haemoglobin (Hb) levels accounted for 46% of the explained dependence in this statistical model. In particular, approximately half of the variability in the multivariate statistical analysis was attributed to the role of Hb and haematocrit (Ht). In addition, the ß-coefficient values for Hb and Ht were statistically higher in relation to donor sex and donor type (single versus repeat). These ß-coefficient values from our data represent the strength and direction of the relationship between the haematological parameters (Hb and Ht) and the specific donor characteristics. A higher ß-coefficient indicates a stronger influence of donor sex and donor type on these parameters, suggesting that these factors contribute significantly to the variation in the Hb and Ht levels. Based on our results, the comprehensive analysis of the entire statistical model of metabolic biomarkers revealed the following hierarchy: Hb > Ht > MCHC > MCV > RBC > MCH. The results obtained showed strong statistical relationships, as indicated by the high values of the key statistical indicators in our analysis. The coefficient of determination (R²) showed that the model explained a significant proportion of the variance in the data, while the F-test statistic confirmed the significance of the predictors. CONCLUSION: These strong statistical dependencies provided a clear justification for selecting this model over others, as it effectively represented the underlying relationships within the data. These statistics help to assess how well the model matches the actual data, thereby helping to reduce the risks associated with blood donation, optimise donor safety, and maintain the quality and efficiency of blood transfusion services.

Whole blood viscosity is associated with reduced myocardial mechano-energetic efficiency in nondiabetic individuals.

INTRODUCTION: This cross-sectional study aimed to investigate the association between myocardial mechano-energetic efficiency (MEE) and whole blood viscosity (WBV) in nondiabetic adults participating in the CATAnzaro MEtabolic RIsk factors (CATAMERI) study. METHODS: 1143 participants underwent an oral glucose tolerance test and an echocardiogram for myocardial MEE per gram of left ventricular mass (MEEi) measurement. WBV was measured as: [0.12 × h] + [0.17 × (p-2.07)], where h is haematocrit and p is plasma protein levels. RESULTS: Study population includes 595 males and 548 females with a mean age of 46 ± 12 years and a mean BMI of 30.0 ± 6.2 kg/m2 . Individuals with normal glucose tolerance were 63%, while those with impaired fasting glucose, impaired glucose tolerance and or the combination of both were 14.3%, 13% and 9.7%, respectively. A univariate analysis showed that MEEi was significantly associated with sex, age, smoking, BMI, waist circumference, total cholesterol, HDL, triglycerides, fasting glucose, fasting insulin, HOMA-IR index, glucose tolerance, C-reactive protein, haematocrit, haemoglobin, plasma protein and WBV. In a multivariable regression model including variables that were significantly associated with MEEi in univariate analysis, MEEi was associated with HOMA-IR (ß = -0.144, p < .001), age (ß = -0.140, p < .001), WBV (ß = -0.129, p < .001) and glucose tolerance (ß = -0.064, p = .04). The independent association between WBV and MEEi remained statistically significant (ß = -0.122, p < .001) when antihypertensive therapy and lipid-lowering therapy were included in the model. CONCLUSION: WBV is associated with decreased myocardial MEE independently of other cardiovascular risk factors.

Effects of handling and surgical implant on juvenile wild trout: Physiological and behavioral impact.

Fish involved in telemetry studies are usually handled, anaesthetized, and subjected to internal tag implantation, all of which have the potential to disrupt the fish's physiology, migratory patterns, food-seeking behavior, growth, and survival. As fish tagging is a widespread standard method in aquaculture, it is crucial to gain a better understanding of the short- and long-term effects on various aspects of fish welfare. The experimental outcomes of each phase of the surgical process and how it affects the fish's ability to recover during the post-tagging period, particularly in small salmonids, are poorly understood. Thus, it is essential to measure the extent of these adverse effects to precisely extrapolate differences in surgical intervention for tagged fish compared to their unmanipulated counterparts. In our study, we explored the post-tagging impacts on wild-captured brown trout (Salmo trutta) (1+) juveniles. We examined the time effect on fish recovery after each phase of the surgical procedure, which included anaesthetized fish, followed by surgery with/without internal tagging, within the first 2 and 25 h post-surgery. Common blood parameters (glucose levels and haematocrit) and endpoints related to swimming behavior, including fish movement, direction, and social distancing aspects, were studied. The findings of the study indicated no significant changes in glucose and haematocrit levels over the observational period. Fish subjected to anesthesia and tagging procedures exhibited a significant decrease in swimming activity, recovering to baseline levels 1 h after anesthesia and 24 h after surgical (tagging) procedures in recirculating aquaculture systems. Tagged fish showed less social proximity than non-tagged fish in the first 2 h post-surgery. A significant effect size was observed between nonsurgical (anesthesia) and surgical (non-tagged/tagged) groups, highlighting a more pronounced impact associated with surgical tag interventions. Our data indicate that the magnitude of behavioral response was significantly influenced by tag weight (~1.4% body/tag weight ratio in water) among manipulated fish groups. Consequently, our study reveals that wild-captured S. trutta juveniles, tagged with commercially available low-weight acoustic tags (V6, 69 kHz), experienced negative effects on swimming performance. In surgical studies, acknowledging potential influences is crucial for accurately inferring fish physiological and behavioral status. Emphasizing fish recovery potential in both short- and long-term periods is essential for quantifying tagging effects. Future research should prioritize exploring alternative tagging technologies and refining methodologies, with a particular focus on assessing telemetry's impact on socioeconomically relevant small salmonids.

Haematocrit monitoring and blood volume estimation during continuous renal replacement therapy.

BACKGROUND: Continuous haemoglobin, venous blood oxygen saturation, and haematocrit (Hct) monitoring is currently not applied during continuous renal replacement therapy (CRRT). Such Hct monitoring enables estimation of changes in blood volume as percentage change (ΔBV%) from therapy start time and is incorporated into intermittent haemodialysis machines but not CRRT machines despite its potential to optimise fluid management in CRRT patients. METHODS: To overcome this problem, we used a standalone monitor (CRIT-LINE®IV, Fresenius Medical Care, Concord, USA) with an associated in-line blood chamber (CRIT-LINE®IV Blood Chamber, Fresenius Medical Care, Concord, USA) and designed our own adaptor connection piece (TekMed and Morriset, Melbourne and Brisbane, Australia) to allow these readings at the vascular access outflow and recorded data for estimated Hct and derived ΔBV% during CRRT. RESULTS: We report on this technique with an illustrative case example and 12 h of CRRT data on the fluid loss rate prescribed, hourly net patient fluid loss (range: 0-308 mL/h), mean arterial pressure, norepinephrine dose (range: 5-14 mcg/min), estimated continuous Hct and ΔBV%, and the otherwise undetected diagnosis of an approximate 15 % decrease in blood volume during the CRRT. CONCLUSION: We have described a technical CRRT circuit modification that can facilitate a previously unavailable assessment of fluid shifts during CRRT. Further application in clinical trials is now possible.

Experimental reduction in blood oxygen-carrying capacity alters foraging behaviour in a colonial waterbird.

Oxidative metabolism is a key component of organismal physiology and it is primarily determined by aerobic capacity, which depends on the capacity of blood to carry oxygen. However, experimental manipulations of blood oxygen-carrying capacity are rarely implemented to test ecophysiological hypotheses in vertebrate populations. Here, we combined an experimental manipulation of blood oxygen-carrying capacity with GPS tracking to test whether suboptimal (reduced) haematological performance affects foraging behaviour in a colonial waterbird, the black-headed gull, Chroicocephalus ridibundus. First, a validation of phenylhydrazine (PHZ) treatment in gulls revealed a 9-18% reduction in haematocrit and blood haemoglobin concentration (via oxidative denaturation and haemolysis of erythrocytes). Then, GPS tracking of experimental (PHZ-treated) and control (saline-treated) gulls during the incubation period provided no support for reduced or suspended engagement in energetically costly activities (long-distance foraging trips) by experimental birds. Instead, we found evidence for fine-scale alterations in foraging behaviour of PHZ-treated individuals, which resulted in fewer foraging trips per unit time, but trips that were longer in duration and distance compared with those of control birds. This suggests reduced foraging performance of experimental birds (e.g. lower capacity to find and collect food during trips) or evasion of social competition, although no differences in the total investment in foraging may also suggest compensatory physiological responses to haemolytic anaemia. Our study contributes to a better understanding of the physio-ecological nexus in non-diving colonial avian species. Whether behavioural effects of reduced aerobic capacity have any implications for gull condition and reproductive performance should be the subject of further investigation.

A novel quantitative method to evaluate the contribution of platelet products to white thrombus formation in reconstituted blood under flow conditions.

BACKGROUND AND OBJECTIVES: Currently, the quality of platelet (PLT) products is evaluated using a series of in vitro tests, which only analyse PLTs as an inspection material. However, it would be ideal to assess the physiological functions of PLTs under conditions similar to the sequential blood haemostatic process. In this study, we attempted to establish an in vitro system where the thrombogenicity of PLT products was evaluated in the presence of red blood cells (RBCs) and plasma using a microchamber under constant shear stress (600/s). MATERIALS AND METHODS: Blood samples were reconstituted by mixing PLT products, standard human plasma (SHP) and standard RBCs. Each component was serially diluted keeping the other two components fixed. The samples were applied onto a flow chamber system (Total Thrombus-formation Analysis System [T-TAS]), and white thrombus formation (WTF) was assessed under large arterial shear conditions. RESULTS: We observed a good correlation between the PLT numbers in the test samples and WTF. The WTF of samples containing ≦10% SHP was significantly lower than those containing ≧40% SHP, and no difference was observed in WTF among samples containing 40%-100% SHP. WTF significantly declined in the absence of RBCs, whereas no change in WTF was observed in the presence of RBCs, over haematocrit range of 12.5%-50%. CONCLUSION: The WTF assessed on the T-TAS using reconstituted blood may serve as a new physiological blood thrombus test to quantitatively determine the quality of PLT products.

Sexual selection for extreme physical performance in a polygynous bird is associated with exceptional sex differences in oxygen carrying capacity.

In many animals, males compete for access to fertile females. The resulting sexual selection leads to sex differences in morphology and behaviour, but may also have consequences for physiology. Pectoral sandpipers are an arctic-breeding polygynous shorebird in which males perform elaborate displays around-the-clock and move over long distances to sample potential breeding sites, implying the need for physiological adaptations to cope with extreme endurance. We examined the oxygen carrying capacity of pectoral sandpipers, measured as the volume percentage of red blood cells in blood (haematocrit, Hct). We found a remarkable sex difference in Hct levels, with males having much higher values (58.9 ± 3.8 s.d.) than females (49.8 ± 5.3 s.d.). While Hct values of male pectoral sandpipers are notable for being among the highest recorded in birds, the sex difference we report is unprecedented and more than double that of any previously described. We also show that Hct values declined after arrival to the breeding grounds in females, but not in males, suggesting that males maintain an aerobic capacity during the mating period equivalent to that sustained during trans-hemispheric migration. We conclude that sexual selection for extreme physical performance in male pectoral sandpipers has led to exceptional sex differences in oxygen carrying capacity.

A Longitudinal Assessment of the Natural Change in Haemoglobin, Haematocrit, and Mean Corpuscular Volume with Age.

INTRODUCTION: We aimed to assess the natural annual trends in the levels of haemoglobin, haematocrit, and mean corpuscular volume (MCV) in a population of adults, together with the influence of different clinical parameters on these trends. METHODS: A retrospective analysis was carried out on data from a large cohort of subjects attending a screening centre in Israel. For each subject, the yearly average change of haemoglobin, haematocrit, and MCV was calculated. Statistical analysis was performed for the whole cohort and for different subgroups. RESULTS: The study included 3,551 subjects. The average annual rates of decline were found to be -0.0550 g/dL (95% confidence interval [CI] -0.0590 g/dL to -0.0503 g/dL) and -0.097% (95% CI -0.112% to -0.083%) for haemoglobin and haematocrit, respectively. An average annual increase in the MCV level by 0.184 fL (95% CI 0.168 fL-0.200 fL) was found. Among men, the rate of decline in haemoglobin was found to be twice as high compared with women -0.06 g/dL versus -0.03 g/dL, respectively (p = 0.0063). In a multivariate analysis, gender remained the only parameter significantly associated with the annual decline of haemoglobin (p = 0.0001). CONCLUSION: An annual average decrease in the levels of haemoglobin and haematocrit together with an annual increase in MCV was found. These changes were more prominent in men.

Effects of SGLT2 inhibitors on haematocrit and haemoglobin levels and the associated cardiorenal benefits in T2DM patients: A meta-analysis.

To explore the effect and magnitude of effect of sodium-glucose cotransporter-2 (SGLT2) inhibitors on haematocrit and haemoglobin and the related cardiorenal benefits in patients with type 2 diabetes mellitus (T2DM), PubMed, Web of Science, CENTRAL and EMBASE were searched to identify eligible trials. Weighted mean differences (WMDs) with 95% confidence intervals (CIs) were calculated using a random-effects model. Seventy-eight studies were included in the meta-analysis. SGLT2 inhibitors significantly increased haematocrit and haemoglobin levels compared with control (total WMD 2.27% [95% CI 2.08, 2.47] and 6.20 g/L [95% CI 5.68, 6.73], respectively). Except for dapagliflozin (p = 0.000), no notable dose-dependent relationship was revealed for other SGLT2 inhibitors. The effect could be sustained or even slightly increased with long-term therapy (coef. =0.009, 95% CI [0.005, 0.013], p = 0.000). In subgroup analyses, haematocrit elevation increased with higher body mass index (BMI). A greater haematocrit elevation could be observed in white patients or when compared with active controls. In conclusion, SGLT2 inhibitors increased haematocrit and haemoglobin levels in T2DM patients. Changes in haematocrit and haemoglobin seem to be surrogate markers of improvement in renal metabolic stress, and important mediators involved in cardiorenal protection.

Risk factors for increased perioperative blood loss during total knee arthroplasty in patients with haemophilia.

INTRODUCTION: Currently, there is a paucity of literature describing the risk factors for increased perioperative blood loss (PBL) during total knee arthroplasty (TKA) in haemophilia. Furthermore, no studies have analysed coagulation factor levels that affect PBL. AIM: To identify the risk factors for increased PBL by incorporating coagulation factor levels following TKA in patients with haemophilic arthropathy. METHODS: A total of 92 TKA (78 haemophilia A and 14 haemophilia B) were performed for haemophilic arthropathy. PBL was calculated using the haemoglobin (Hb) balance method, and patients were categorised into two groups: group H (higher blood loss than the mean PBL, n = 36) and group L (lower blood loss than the mean PBL, n = 56). Body mass index (BMI), operation day Hb, haematocrit and coagulation factor level (VIII or IX) were analysed, including demographic and laboratory data. RESULTS: The mean PBL volume during TKA for haemophilic arthropathy of the knee was 542.3 ± 361.7 mL. Multivariate analysis revealed that lower haematocrit on the operation day (odds ratio [OR], .633; 95% confidence interval [CI], .511-.786; p < .001) and coagulation factor level (OR .970, CI .941-.999; p = .046) were independent risk factors for increased PBL. Receiver-operating characteristic analysis identified these cutoff values for predicting increased PBL: operation day coagulation factor level 93.5% (sensitivity, 70.4%; specificity, 67.6%) and haematocrit level of 38.2% (sensitivity, 85.7%; specificity, 80.6%). CONCLUSIONS: The PBL increased as haematocrit and coagulation factor levels decreased on the operation day. A coagulation factor level <93.5% or haematocrit level of <38.2% may be a significant risk factor for increasing PBL. LEVEL OF EVIDENCE: Level IV, Case Series, Treatment Study.

Haematocrit level in obesity hypoventilation syndrome: a predictor of mortality?

BACKGROUND: The connection between obstructive sleep apnea and secondary erythrocytosis is controversial. We hypothesised that there may be a higher prevalence of erythrocytosis in patients with obesity hypoventilation syndrome (OHS) due to persistent hypoxemia. METHODS: The study was a retrospective, cross-sectional review of patients with OHS derived from an established cohort of "non-invasive ventilation" patients at the Department of Sleep Medicine at the Royal Infirmary Medical Centre, Edinburgh (2004-2017). Relevant clinical data were obtained from patient records. RESULTS: The cohort comprised 74 patients with OHS, 44 men (60%), mean age at diagnosis 54 ± 10 years. The mean haematocrit level for the group overall was 0.44, in men 0.45, and in women 0.41. Of 11 patients with erythrocytosis (15%), 7 were men. Thirteen patients (18%) died during follow-up (2004-2017). There was a statistically significant increase in risk of death in patients with higher and lower haematocrit levels compared to that in patients with OHS who had normal haematocrits. CONCLUSIONS: This is the first study showing increased prevalence of erythrocytosis in OHS patients. There was a "U"-shaped correlation with mortality according to haematocrit levels.

Haematology reference values for Dicentrarchus labrax and Sparus aurata: A systematic review and meta-analysis.

Haematological parameters are frequently used as physiological indicators in aquaculture studies. These parameters also have extended applications in clinical evaluation, diagnosis and prognosis in fish health status. However, no normal reference range of values has been demonstrated in depth for any of these haematological parameters for the European sea bass (Dicentrarchus labrax) or gilthead seabream (Sparus aurata). The main objective of this article is to present for the first time through extended literature review, the haematological parameters normal range values for the two most important aquaculture fish species farmed in Mediterranean Sea, D. labrax and S. aurata, and to demonstrate their similarities and their differences. In this article, we also discuss the environmental and external factors affecting their normal blood parameters values and we propose fundamental guidelines on the reporting units.

Effect of low-dose Piscirickettsia salmonis infection on haematological-biochemical blood parameters in Atlantic salmon (Salmo salar).

Piscirickettsia salmonis is the etiological agent of Piscirickettsiosis, a severe disease that affects Atlantic salmon (Salmo salar) farmed in Chile and many other areas (Norway, Scotland, Ireland, Canada and the USA). This study investigated the effects of low-dose P. salmonis infection (1 × 102 CFU/ml) on Atlantic salmon. In this study, we challenged fish with an isolated representative of the EM-90 genogroup via intraperitoneal injection for 42 days. Infected fish displayed decreased haematocrit and haemoglobin levels at day 13 post-infection, indicating erythropenia, haemolysis and haemodilution. Conversely, their white blood cell counts increased on days 13 and 21 post-infection. Additionally, their iron levels decreased from day 2 post-infection, indicating iron deficiency and an inability to retrieve stored iron before infection. Their magnesium levels also decreased at day 28 post-infection, possibly due to osmoregulatory problems. Also, we observed an increase in lactate dehydrogenase activity on days 5, 21, and 28 post-infection, suggesting early symptoms of hepatotoxicity. Later analyses determined a decrease in plasma glucose levels from day 2 post-infection. This may be attributed to the hypoxic conditions caused by P. salmonis, leading to an excess utilization of stored carbohydrates. Our results suggest that the blood parameters we studied are useful for monitoring the physiological status of Atlantic salmon infected with P. salmonis.

Impact of sublethal phenol in freshwater fish Labeo rohita on biochemical and haematological parameters.

Phenol, an aromatic chemical commonly found in domestic and industrial effluents, upon its introduction into aquatic ecosystems adversely affects the indigenous biota, the invertebrates and the vertebrates. With the increased demand for agrochemicals, a large amount of phenol is released directly into the environment as a byproduct. Phenol and its derivatives tend to persist in the environment for longer periods which in turn poses a threat to both humans and the aquatic ecosystem. In our current study, the response of Labeo rohita to sublethal concentrations of phenol was observed and the results did show a regular decrease in biochemical constituents of the targeted organs. Exposure of Labeo rohita to sublethal concentration of phenol (22.32 mg/L) for an epoch of 7, 21 and 28 days shows a decline in lipid, protein, carbohydrate content and phosphatase activity in target organs such as the gills, muscle, intestine, liver and kidney of the fish. The present study also aims to investigate the toxic effects of phenol with special reference to the haematological parameters of Labeo rohita. At the end of the exposure period, the blood of the fish was collected by cutting the caudal peduncle with a surgical scalpel. And it was observed that the red blood corpuscle count (RBC), white blood corpuscle (WBC), haemoglobin count (Hb), packed cell volume (PCV), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) values showed a decline after exposure to phenol for 7 days, while white blood corpuscle (WBC) shows an increased count. At 21 days and 28 days, all the haematological parameters showed a significant decrease.

Haematological responses to repeated sprints in hypoxia across different sporting modalities.

The aim was to determine the effects of repeated-sprint training in hypoxia on haematocrit and haemoglobin in different sporting modalities. Seventy-two participants were randomly allocated to Active-Repeated sprint in hypoxia (A-RSH, n= 8); Active-Repeated sprint in normoxia (A-RSN, n= 8); Active-Control (A-CON, n= 8); Team Sports-RSH (T-RSH, n= 8); Team Sports-RSN (T-RSN, n= 8); Team Sports-Control (T-CON, n= 8); Endurance-RSH (E-RSH, n= 8); Endurance-RSN (E-RSN, n= 8); Endurance-Control (E-CON, n= 8). Sessions consisted of two sets of five sprints of 10 swith recovery of 20 sbetween sprints and 10 min between sets. Blood samples for haematocrit and haemoglobin concentrations were obtained before and after, and 2 weeks after cessation. Haematocrit and haemoglobin were lower for the E-RSN group following 2 weeks of cessation of protocol compared with E-RSH (p = 0.035) and E-CON (p = 0.045). Haematocrit of the A-RSH group was higher compared with baseline (p = 0.05) and Post (p = 0.05). Similarly, the T-RSH group demonstrated increases in haematocrit following 2 weeks of cessation compared with Post (p = 0.04). Repeated Sprint Training in Hypoxia had different haematological effects depending on sporting modality.

Splenic responses to a series of repeated maximal static and dynamic apnoeas with whole-body immersion in water.

NEW FINDINGS: What is the central question of this study? Splenic contractions occur in response to apnoea-induced hypoxia with and without face immersion in water. However, the splenic responses to a series of static or dynamic apnoeas with whole-body water immersion in non-divers and elite breath-hold divers are unknown. What is the main finding and its importance? Static and dynamic apnoeas were equally effective in stimulating splenic contractions across non-divers and elite breath-hold divers. These findings demonstrate that the magnitude of the splenic response is largely dictated by the degree of the hypoxemic stress encountered during voluntary apnoeic epochs. ABSTRACT: Splenic contractions occur in response to apnoea-induced hypoxia with and without facial water immersion. However, the splenic responses to a series of static (STA) or dynamic (DYN) apnoeas with whole-body water immersion in non-divers (NDs) and elite breath-hold divers (EBHDs) are unknown. EBHD (n = 8), ND (n = 10) and control participants (n = 8) were recruited. EBHD and ND performed a series of five maximal DYN or STA on separate occasions. Control performed a static eupnoeic (STE) protocol to control against any effects of water immersion and diurnal variation on splenic volume and haematology. Heart rate (HR) and peripheral oxygen saturation (SpO2 ) were monitored for 30 s after each apnoea. Pre- and post-apnoeic splenic volumes were quantified ultrasonically, and blood samples were drawn for haematology. For EBHD and ND end-apnoeic HR was higher (P < 0.001) and SpO2 was lower in DYN (P = 0.024) versus STA. EBHD attained lower end-apnoeic SpO2 during DYN and STA than NDs (P < 0.001). Splenic contractions occurred following DYN (EBHD, -47 ± 6%; ND, -37 ± 4%; P < 0.001) and STA (EBHD, -26 ± 4%; ND, -26 ± 8%; P < 0.01). DYN-associated splenic contractions were greater than STA in EBHD only (P = 0.042). Haemoglobin concentrations were higher following DYN only (EBHD, +5 ± 8g/L  , +4 ± 2%; ND, +8 ± 3 g/L , +4.9 ± 3%; P = 0.019). Haematocrit remained unchanged after each protocol. There were no between group differences in post-apnoeic splenic volume or haematology. In both groups, splenic contractions occurred in response to STA and DYN when combined with whole-body immersion. DYN apnoeas, were effective at increasing haemoglobin concentrations but not STA apnoeas. Thus, the magnitude of the splenic response relates to the hypoxemic stress encountered during apnoeic epochs.

Rational use of ultrasonography with triaging of patients to detect dengue plasma leakage in resource limited settings: a prospective cohort study.

OBJECTIVES: To compare the traditional haematocrit-based criteria (>20% rise above baseline) with ultrasonography for diagnosing plasma leakage in dengue fever and to identify clinical indicators for triaging patients in resource-limited settings when the demand for ultrasonography is high. METHODS: The Colombo Dengue Study is a prospective observational cohort study recruiting dengue patients in the first three days of dengue fever, before plasma leakage. Serial haematocrit assessments and ultrasonography were performed in patients recruited from October 2017 to February 2020. Clinical signs/symptoms and laboratory investigation results independently associated with ultrasound detected plasma leakage were identified with a derivation cohort and confirmed in a validation cohort. RESULTS: 129 of 426 patients had ultrasonography-confirmed plasma leakage while 146 had a haematocrit rise >20%. Those positive on ultrasonography were also likely to fulfil the haematocrit-based criteria (OR: 4.42, 95% CI: 2.85-6.86), but the two groups did not overlap fully. In the derivation cohort (n = 317), platelet count <97 000/µl, AST/ALT > 51 IU/l and having abdominal pain in the first three days of fever were independent predictors of ultrasound-detected plasma leakage. In the validation cohort (n = 109), the combination of low platelet count and high aminotransferase level had better predictive capacity in terms of sensitivity and specificity. CONCLUSION: Dengue patients should be monitored with both serial haematocrit and ultrasonography whenever possible and plasma leakage should be diagnosed by either one of these criteria. If accessibility to scans is limited, platelet count, serum transaminase levels and presence of abdominal pain are useful to triage patients.

Extracellular volume quantification using synthetic haematocrit assessed from native and post-contrast longitudinal relaxation T1 times of a blood pool.

BACKGROUND: In terms of cardiovascular magnetic resonance are haematocrit values required for calculation of extracellular volume fraction (ECV). Previously published studies have hypothesized that haematocrit could be calculated from T1 blood pool relaxation time, however only native T1 relaxation time values have been used and the resulting formulae had been both in reciprocal and linear proportion. The aim of the study was to generate a synthetic haematocrit formula from only native relaxation time values first, calculate whether linear or reciprocal model is more precise in haematocrit estimation and then determine whether adding post-contrast values further improve its precision. METHODS: One hundred thirty-nine subjects underwent CMR examination. Haematocrit was measured using standard laboratory methods. Afterwards T1 relaxation times before and after the application of a contrast agent were measured and a statistical relationship between these values was calculated. RESULTS: Different linear and reciprocal models were created to estimate the value of synthetic haematocrit and ECV. The highest coefficient of determination was observed in the combined reciprocal model "- 0.047 + (779/ blood native) - (11.36/ blood post-contrast)". CONCLUSIONS: This study provides more evidence that assessing synthetic haematocrit and synthetic ECV is feasible and statistically most accurate model to use is reciprocal. Adding post-contrast values to the calculation was proved to improve the precision of the formula statistically significantly.

Prevalence of polycythaemia with different formulations of testosterone therapy in transmasculine individuals.

BACKGROUND: Masculinising hormone therapy with testosterone is used to align an individual's physical characteristics with his or her gender identity. Testosterone therapy is typically administered via intramuscular or transdermal routes, and polycythaemia is the most common adverse event. AIMS: To compare the risk of polycythaemia with different formulations of testosterone therapy in transmasculine individuals. METHODS: A retrospective cross-sectional analysis was undertaken of transmasculine individuals at a primary and secondary care clinic in Melbourne, Australia. A total of 180 individuals who were on testosterone therapy for >6 months was included. Groups included those receiving: (i) intramuscular testosterone undecanoate (n = 125); (ii) intramuscular testosterone enantate (n = 31); or (iii) transdermal testosterone (n = 24). Outcome was prevalence of polycythaemia (defined as haematocrit > 0.5). RESULTS: Mean age was 28.4 (8.8) years, with a median duration of testosterone therapy of 37.7 (24.2) months; 27% were smokers. There was no difference between groups in serum total testosterone concentration measured. While there was no difference between groups in haematocrit, there was a higher proportion of patients with polycythaemia in those who were on intramuscular testosterone enantate (23.3%) than on transdermal testosterone (0%), P = 0.040. There was no statistically significant difference in polycythaemia between intramuscular testosterone undecanoate (15%) and transdermal testosterone, P = 0.066 nor between intramuscular testosterone enantate and undecanoate, P = 0.275. CONCLUSIONS: One in four individuals treated with intramuscular testosterone enantate and one in six treated with testosterone undecanoate had polycythaemia. No individual treated with transdermal testosterone had polycythaemia. This highlights the importance of regular monitoring of haematocrit in transmasculine individuals treated with testosterone, and findings may inform treatment choices.

Regulation of splenic contraction persists as a vestigial trait in white-blooded Antarctic fishes.

In fishes, the spleen can function as an important reservoir for red blood cells (RBCs), which, following splenic contraction, may be released into the circulation to increase haematocrit during energy-demanding activities. This trait is particularly pronounced in red-blooded Antarctic fishes in which the spleen can sequester a large proportion of RBCs during rest, thereby reducing blood viscosity, which may serve as an adaptation to life in cold environments. In one species, Pagothenia borchgrevinki, it has previously been shown that splenic contraction primarily depends on cholinergic stimulation. The aim of the present study was to investigate the regulation of splenic contraction in five other Antarctic fish species, three red-blooded notothenioids (Dissostichus mawsoni Norman, 1937, Gobionotothen gibberifrons Lönnberg, 1905, Notothenia coriiceps Richardson 1844) and two white-blooded "icefish" (Chaenocephalus aceratus Lönnberg, 1906 and Champsocephalus gunnari Lönnberg, 1905), which lack haemoglobin and RBCs, but nevertheless possess a large spleen. In all species, splenic strips constricted in response to both cholinergic (carbachol) and adrenergic (adrenaline) agonists. Surprisingly, in the two species of icefish, the spleen responded with similar sensitivity to red-blooded species, despite contraction being of little obvious benefit for releasing RBCs into the circulation. Although the icefish lineage lost functional haemoglobin before diversifying over the past 7.8-4.8 millions of years, they retain the capacity to contract the spleen, likely as a vestige inherited from their red-blooded ancestors.