Association between hemoglobin concentration and hypertension risk in native Tibetans at high altitude

Previous studies examining the association between hemoglobin concentration and hypertension have yielded inconsistent results. There is still a lack of evidence regarding the association between hemoglobin concentration and hypertension risk in native Tibetans at high altitude. We performed this cross-sectional study in Luhuo County of Ganzi Tibetan Autonomous Prefecture (average altitude of 3500 m). In this study, we enrolled 1547 native Tibetans. The association between hemoglobin concentration and hypertension risk was examined by multivariate binary logistic regression and smooth curve fitting. Native Tibetans with hypertension had significantly higher hemoglobin concentrations than those without hypertension (165.9 ± 21.5 g/L vs. 157.7 ± 19.2 g/L, P < 0.001). An increase in hemoglobin concentration of 1 g/L was associated with hypertension (odds ratio [OR] 1.02, 95% confidence interval [CI] 1.01-1.02) after confounder adjustment. The highest hemoglobin concentration group (exceeding 173 g/L) was associated with an increased hypertension risk compared with the bottom quartile of hemoglobin concentration (OR 2.39, 95% CI 1.48-3.85). Hemoglobin concentration (per 1 g/L change) exceeding 176 g/L was significantly associated with an increased hypertension risk (OR 1.04, 95% CI 1.03-1.06). Additionally, high-altitude polycythemia significantly increased the hypertension risk compared with a normal hemoglobin concentration (OR 2.92, 95% CI 1.25-6.86). A similar result was observed for mild polycythemia (OR 1.74, 95% CI 1.29-2.34). In conclusion, hemoglobin concentration was associated with hypertension risk in native Tibetans. When the hemoglobin concentration exceeded a certain value (approximately 176 g/L), the risk of hypertension was significantly increased.

Assessing the impact of transfusion thresholds in patients with septic acute kidney injury: a retrospective study

Background

Sepsis is a severe condition that often leads to complications such as acute kidney injury, which significantly increases morbidity and mortality rates. Septic AKI (S-AKI) is common in ICU patients and is associated with poor outcomes. However, there is no consensus on the optimal transfusion threshold for achieving the best clinical results. This retrospective study aims to investigate the relationship between different transfusion thresholds during hospitalization and the prognosis of septic AKI.

Methods

Data from patients with S-AKI was extracted from MIMIC-IV. Based on the lowest hemoglobin level 24 h before transfusion, patients were divided into high-threshold (≥7 g/L) and low-threshold (<7 g/L) groups. We compared the outcomes between these two groups, including hospital and ICU mortality rates as primary outcomes, and 30 days, 60 days, and 90 days mortality rates, as well as duration of stay in ICU and hospital as secondary outcomes.

Results

A total of 5,654 patients were included in our study. Baseline characteristics differed significantly between the two groups, with patients in the low-threshold group generally being younger and having higher SOFA scores. After performing propensity score matching, no significant differences in survival rates were found between the groups. However, patients in the low-threshold group had a longer overall hospital stay.

Conclusion

A lower transfusion threshold does not impact the mortality rate in S-AKI patients, but it may lead to a longer hospital stay.

Relationship between Blood Volume, Blood Lactate Quantity, and Lactate Concentrations during Exercise

We wanted to determine the influence of total blood volume (BV) and blood lactate quantity on lactate concentrations during incremental exercise. Twenty-six healthy, nonsmoking, heterogeneously trained females (27.5 ± 5.9 ys) performed an incremental cardiopulmonary exercise test on a cycle ergometer during which maximum oxygen uptake (V·O_2max), lactate concentrations ([La^-]) and hemoglobin concentrations ([Hb]) were determined. Hemoglobin mass and blood volume (BV) were determined using an optimised carbon monoxide-rebreathing method. V·O_2max and maximum power (P_max) ranged between 32 and 62 mL·min^-1·kg^-1 and 2.3 and 5.5 W·kg^-1, respectively. BV ranged between 81 and 121 mL·kg^-1 of lean body mass and decreased by 280 ± 115 mL (5.7%, p = 0.001) until P_max. At P_max, the [La^-] was significantly correlated to the systemic lactate quantity (La^-, r = 0.84, p < 0.0001) but also significantly negatively correlated to the BV (r = -0.44, p < 0.05). We calculated that the exercise-induced BV shifts significantly reduced the lactate transport capacity by 10.8% (p < 0.0001). Our results demonstrate that both the total BV and La^- have a major influence on the resulting [La^-] during dynamic exercise. Moreover, the blood La^- transport capacity might be significantly reduced by the shift in plasma volume. We conclude, that the total BV might be another relevant factor in the interpretation of [La^-] during a cardio-pulmonary exercise test.

A study on the correlation between hemoglobin concentration and the storage quality of suspended red blood cells prepared from the whole blood of Tibetan male residents

Background

Previous studies reported that the blood of Tibetans living at different altitudes may vary slightly. There is evidence that the harsh environmental conditions at high altitudes, such as low pressure and hypoxia, may affect the morphology and hemorheology of red blood cells (RBCs). Hypoxia would increase the levels of hemoglobin ([Hb]) and hematocrit (Hct), potentially increasing blood hyperviscosity and compromising blood collection and transfusions. Therefore, it is critical to investigate the in vitro storage quality of Tibetan RBCs.

Objectives

In this study, the in vitro quality of suspended RBCs (SRBCs) prepared from whole blood (WB) of Tibetan residents with varying Hb concentrations ([Hb]) was measured during storage, and the relationship between the major factors in RBC storage and [Hb] was studied.

Materials and methods

The WB of Tibetan men was divided into three groups based on [Hb] levels (group A: 120 < Hb ≤ 185 g/L; group B: 185 < Hb ≤ 210 g/L; group C: Hb > 210 g/L). The SRBCs prepared from WB were examined aseptically on days 1, 14, 21, and 35 after storage.

Results

[Hb] was not correlated with mean corpuscular volume (MCV), adenosine triphosphate (ATP), pH, P50, and hemolysis. There was a moderate or strong negative association between platelets (PLT) and [Hb] from days 1 to 35, and the PLT number of group C was lower than group A during storage. Group C had the highest change rates of electrolytes, glucose, and lactate, and there were moderate or strong positive correlations between lactate and [Hb] (r = 0.3772, p = 0.0045), glucose and [Hb] (r = 0.5845, p < 0.0001), Na⁺ and [Hb] (r = 0.3966, p = 0.0027), and K⁺ and [Hb] (r = 0.4885, p = 0.0002). Group B had the highest change rates of 2,3-DPG on day 35, and there was a negative correlation between 2,3-DPG and [Hb] (r = -0.4933, p = 0.0001).

Conclusions

These new data on the [Hb] could have implications for researchers wishing to study the storage quality of Tibetan SRBCs, particularly in the context of erythrocyte metabolism, and we propose finding a new, suitable alternative solution for plateau SRBCs, particularly the blood with [Hb] greater than 185 g/L. Our results could have important implications for researchers wishing to study the potential framework of high-altitude-induced SRBC storage lesions.

Splenic contraction and cardiovascular responses are augmented during apnea compared to rebreathing in humans

The spleen contracts during apnea, releasing stored erythrocytes, thereby increasing systemic hemoglobin concentration (Hb). We compared apnea and rebreathing periods, of equal sub-maximal duration (mean 137 s; SD 30), in eighteen subjects to evaluate whether respiratory arrest or hypoxic and hypercapnic chemoreceptor stimulation is the primary elicitor of splenic contraction and cardiovascular responses during apnea. Spleen volume, Hb, cardiovascular variables, arterial (SaO₂), cerebral (ScO₂), and deltoid muscle oxygen saturations (SmO₂) were recorded during the trials and end-tidal partial pressure of oxygen (P_ETO₂) and carbon dioxide (P_ETCO₂) were measured before and after maneuvers. The spleen volume was smaller after apnea, 213 (89) mL, than after rebreathing, 239 (95) mL, corresponding to relative reductions from control by 20.8 (17.8) % and 11.6 (8.0) %, respectively. The Hb increased 2.4 (2.0) % during apnea, while there was no significant change with rebreathing. The cardiovascular responses, including bradycardia, decrease in cardiac output, and increase in total peripheral resistance, were augmented during apnea compared to during rebreathing. The P_ETO₂ was higher, and the P_ETCO₂ was lower, after apnea compared to after rebreathing. The ScO₂ was maintained during maneuvers. The SaO₂ decreased 3.8 (3.1) % during apnea, and even more, 5.4 (4.4) %, during rebreathing, while the SmO₂ decreased less during rebreathing, 2.2 (2.8) %, than during apnea, 8.3 (6.2) %. We conclude that respiratory arrest per se is an important stimulus for splenic contraction and Hb increase during apnea, as well as an important initiating factor for the apnea-associated cardiovascular responses and their oxygen-conserving effects.

An Individualized Red Blood Cell Transfusion Strategy Using Pediatric Perioperative-Transfusion-Trigger Score Reduced Perioperative Blood Exposure for Children: A Randomized Controlled Clinical Trial

Objective

The optimal red blood cell transfusion strategy for children remains unclear. We developed an individualized red blood cell transfusion strategy for children and tested the hypothesis that transfusion guided by this strategy could reduce blood exposure, without increasing perioperative complications in children.

Methods

In this randomized controlled clinical trial, 99 children undergoing noncardiac surgeries who had blood loss of more than 20% total blood volume were randomly assigned to an individualized-strategy group using Pediatric Perioperative-Transfusion-Trigger Score or a control group. The amount of transfused red blood cell was counted, and patients were followed up for postoperative complications within 30 days.

Results

Twenty-six children (53.1%) in the individualized-strategy group received transfusion perioperatively, as compared with 37 children (74%) in the control group (p < 0.05). During surgery, children in the individualized-strategy group were exposed to fewer transfusions than in the control group (0.87±1.03 vs 1.33±1.20 Red-Blood-Cell units per patient, p = 0.02). The incidence of severe complications in the individualized-strategy group had a lower trend compared to the control group (8.2% vs 18%, p = 0.160). No significant difference was found in the other outcomes.

Conclusion

This trial proved that red blood cell transfusion guided by the individualized strategy reduced perioperative blood exposure in children, without increasing the incidence of severe complications. This conclusion needs to be reaffirmed by larger-scale, multicenter clinical trials.

Evaluation of red blood cell transfusion threshold in the management of brain-dead organ donors

The disparity between the demand and supply of organs has necessitated an expansion of the criteria for organ donation. Consequently, numerous guidelines have been proposed for managing brain-dead organ donors (BDODs) to improve their organ function and the organ procurement rate. Therefore, we aimed to evaluate the previously recommended threshold for red blood cell transfusion in BDODs. Medical records of BDODs were retrospectively reviewed from January 2012 to December 2021. We enrolled BDODs who stayed for more than 24 hours at an hospital organ procurement organization. We analyzed their organ function and the rate of organ procurement according to the hemoglobin concentration. A total of 111 BDODs were enrolled and divided into the following 2 groups: hemoglobin (Hb) ≥ 10 g/dL (45.0 %) and Hb < 10 g/dL (55.0 %). There were no significant differences between the groups in the total bilirubin, creatinine, arterial blood lactate, and the rate of organ procurement. A correlation analysis did not reveal any association between the hemoglobin concentration and organ function of the BDODs. Hemoglobin concentration of 10 g/dL cannot be considered a threshold for red blood cell transfusion. Furthermore, organ function is not correlated with a hemoglobin concentration > 7 g/dL. Restrictive transfusion strategy is appropriate for BDOD management.

Hemoglobin Mass and Blood Volume in Patients With Altitude-Related Polycythemia

Patients with chronic mountain sickness (CMS) have a high hemoglobin concentration [Hb] due to increased hemoglobin mass (Hbmass) and possibly reduced plasma volume (PV). The values of Hbmass, PV and blood volume (BV) have been described differently, and the relationships between [Hb] and Hbmass or PV are poorly understood. This study obtained representative Hbmass, PV and BV data from healthy, high-altitude residents and CMS patients and quantified the dependency of [Hb] on Hbmass and PV.

METHODS

Eighty-seven subjects born at high altitude (∼3,900 m) were enrolled. Thirty-four had CMS (CMS), 11 had polycythemia without CMS (intermediate, IM), 20 were healthy highlanders (HH), and 22 living near sea level (SL, 420 m) served as the sea level (SL) control group. Hbmass, PV and BV were determined using a CO-rebreathing method modified for assessing polycythemia patients. Furthermore, [Hb], hematocrit (Hct), plasma erythropoietin concentration [EPO] and blood gas and acid-base status were determined.

RESULTS

In the HH group, Hbmass was 27% higher (940 ± 105 g) than in the SL group (740 ± 112 g) and 72% (1,617 ± 265 g) lower than in the CMS group. The PV in the HH group was similar to that in the SL group (-6%) and 15% higher than that in the CMS group (p < 0.001). In the HH group, the BV (5,936 ± 673 ml) did not differ from that in the SL group and was 28% lower than in the CMS group (7,606 ± 1075 ml, p < 0.001). Log [EPO] was slightly increased in the CMS group relative to the HH group (p < 0.01). All values in the IM group were between those in the HH and CMS groups. Hbmass and BV were positively correlated, and PV was negatively correlated with peripheral O₂ saturation. Increased Hbmass and decreased PV contributed approximately 65 and 35%, respectively, to the difference in [Hb] between the HH (17.1 ± 0.8 g/dl) and CMS (22.1 ± 1.0 g/dl) groups.

CONCLUSIONS

In CMS patients, the decrease in PV only partially compensated for the substantial increase in Hbmass, but it did not prevent an increase in BV; the decrease in PV contributed to an excessively high [Hb].

The Effects of Intravenous Iron Infusion on Preoperative Hemoglobin Concentration in Iron Deficiency Anemia: Retrospective Observational Study

Background

An iron infusion pathway using Ferrinject (ferric carboxymaltose) was implemented at Southend University Hospital for preoperative surgical patients with iron deficiency anemia undergoing major surgery. This was based on a treatment algorithm proposed by Munting and colleagues according to the international consensus statement on perioperative management of anemia and the UK National Institute for Health and Care Excellence (NICE) guidelines. These guidelines state that intravenous iron is indicated when oral iron is poorly tolerated or ineffective, there is insufficient time to surgery, or due to a functional iron deficiency.

Objective

The objective of this study was to evaluate the change in adult hemoglobin (Hb) concentration (g/L) after Ferrinject infusion at the time of surgery.

Methods

Data were retrospectively collected on all surgical patients that received an iron infusion preoperatively for iron deficiency anemia from July 2019 to April 2020. Nonsurgical, obstetric, and pediatric patients, and those without a postinfusion Hb level measurement were excluded. Data collected included the Hb, ferritin, and transferrin levels pre and postinfusion; correct dose of intravenous iron received; and any adverse reactions noted.

Results

Thirty-two surgical patients with iron deficiency anemia received intravenous iron between July 2019 and April 2020 prior to surgery. The average pre and post iron infusion Hb concentration across the cohort was 97 g/L and 114 g/L, respectively (18% increase; P=.001). Two (6%) patients had a posttransfusion Hb level ≥130 g/L prior to surgery after infusion. Nine patients had both a pre and postinfusion ferritin level recorded, which showed an increase from 12 ng/mL preinfusion to 94 ng/mL postinfusion (P=.02). Twenty-three (72%) patients did not receive the full dose of intravenous iron based on their Hb level and weight. Twenty-four (75%) patients received an iron infusion >2 weeks prior to surgery and the other 8 (25%) patients received the infusion <2 weeks before their surgery. There was an average increase in Hb of 22% (21 g/L, 95% CI 13-28) and 5% (5 g/L, 95% CI 1-10), respectively, across the two groups (P=.03). There were no documented adverse reactions to intravenous iron.

Conclusions

Intravenous iron is an effective intervention to improve the Hb concentration in patients with iron deficiency anemia despite the majority of patients not receiving the full dose based on their baseline Hb level and weight. Increasing the interval time between infusion and surgery was associated with a greater increase in Hb, with only a minimal increase observed if given less than 2 weeks prior to surgery.

Is Hemoglobin Concentration a Linear Predictor of Mortality in Older Adults From Chinese Longevity Regions?

Introduction: The association patterns of hemoglobin (HB) concentrations with mortality among the longevity older adults are unclear. We aimed to evaluate the relationship among older adults form Chinese longevity regions. Methods: We included 1,785 older adults aged ≥65 years (mean age, 86.7 years; 1,002 women, 783 men) from the community-based Chinese Longitudinal Healthy Longevity Survey. We estimated the hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause mortality using multivariable Cox proportional hazards models and Cox models with restricted cubic spline. Results: In total, 999 deaths occurred during a median follow-up of 5.4 years from 2011 to 2017. Restricted cubic spline analysis found no non-linear association between HB concentrations and all-cause mortality after a full adjustment for covariates among the older adults form longevity regions (p > 0.05 for non-linearity). The risk for all-cause mortality was significantly higher in the groups with HB concentration of <11.0 g/dL (HR: 1.37, 95% CI: 1.10-1.70) and 11.0-12.0 g/dL (HR: 1.25, 95% CI: 1.01-1.54); the risk of all-cause mortality was significantly lower in the groups with HB concentration ≥14.0 g/dL (HR: 0.76, 95% CI: 0.60-0.97) compared with the reference group (13.0-13.9 g/dL). Conclusions: Among older adults form Chinese longevity regions, HB concentrations were found to be inversely and linearly associated with all-cause mortality. Further prospective intervention trials are needed to confirm whether higher HB concentrations had a lower risk of mortality in these older adults.

Effect of Exercise-Induced Reductions in Blood Volume on Cardiac Output and Oxygen Transport Capacity

We wanted to demonstrate the relationship between blood volume, cardiac size, cardiac output and maximum oxygen uptake (V.O_2max) and to quantify blood volume shifts during exercise and their impact on oxygen transport. Twenty-four healthy, non-smoking, heterogeneously trained male participants (27 ± 4.6 years) performed incremental cycle ergometer tests to determine V.O_2max and changes in blood volume and cardiac output. Cardiac output was determined by an inert gas rebreathing procedure. Heart dimensions were determined by 3D echocardiography. Blood volume and hemoglobin mass were determined by using the optimized CO-rebreathing method. The V.O_2max ranged between 47.5 and 74.1 mL⋅kg^–1⋅min^–1. Heart volume ranged between 7.7 and 17.9 mL⋅kg^–1 and maximum cardiac output ranged between 252 and 434 mL⋅kg^–1⋅min^–1. The mean blood volume decreased by 8% (567 ± 187 mL, p = 0.001) until maximum exercise, leading to an increase in [Hb] by 1.3 ± 0.4 g⋅dL^–1 while peripheral oxygen saturation decreased by 6.1 ± 2.4%. There were close correlations between resting blood volume and heart volume (r = 0.73, p = 0.002), maximum blood volume and maximum cardiac output (r = 0.68, p = 0.001), and maximum cardiac output and V.O_2max (r = 0.76, p < 0.001). An increase in maximum blood volume by 1,000 mL was associated with an increase in maximum stroke volume by 25 mL and in maximum cardiac output by 3.5 L⋅min^–1. In conclusion, blood volume markedly decreased until maximal exhaustion, potentially affecting the stroke volume response during exercise. Simultaneously, hemoconcentrations maintained the arterial oxygen content and compensated for the potential loss in maximum cardiac output. Therefore, a large blood volume at rest is an important factor for achieving a high cardiac output during exercise and blood volume shifts compensate for the decrease in peripheral oxygen saturation, thereby maintaining a high arteriovenous oxygen difference.

A significant decrease in hemoglobin concentrations may predict occurrence of necrotizing enterocolitis in preterm infants with late-onset sepsis

OBJECTIVE

This study aimed to examine the clinical value of a decrease in hemoglobin concentration (HC) after the onset of sepsis for predicting occurrence of necrotizing enterocolitis (NEC) in preterm infants with late-onset sepsis.

METHODS

We performed a retrospective cohort study between January 2015 and January 2020. Premature neonates (gestational age <37 weeks) with late-onset sepsis (age >3 days) were enrolled. According to the degree of reduction in HC, neonates were divided into the non-decrease group, mild decrease group, and severe decrease group. Demographic data, perinatal conditions, blood cell count analysis, blood culture, and treatment measures were compared.

RESULTS

Eighty premature infants with sepsis were studied. The mortality rate and incidence of NEC were significantly higher in the severe decrease group than in the non-decrease and mild decrease groups. Significant differences were observed in the decrease in HC, red blood cell transfusion, and ventilator application between the NEC and non-NEC groups. A significant decrease in HC was an independent risk factor for NEC in preterm infants with sepsis.

CONCLUSION

A significant decrease in HC is an independent risk factor for NEC and may predict the occurrence of NEC in preterm infants with sepsis.

Effect Modification by Sex of the Hemoglobin Concentration on Frailty Risk in Hospitalized Older Patients

Background

Hemoglobin concentration differs by sex, possibly affecting any association between hemoglobin and frailty. This study aimed to evaluate the potential interaction effect of hemoglobin and sex on frailty in Chinese older inpatients.

Methods

A cross-sectional study was conducted between February 2015 and November 2017 in a tertiary hospital. Frailty was defined by the Fried phenotype. Hemoglobin concentration was measured with a standard procedure. Covariates included demographics, clinical characteristics, and serum biomarkers. Logistic regression was applied to examine the association between hemoglobin concentration and frailty. The relative excess risk due to interaction (RERI), attributable proportion due to interaction (AP), and synergy index (SI) were used to evaluate the additive interaction.

Results

A total of 619 older inpatients [mean age 69.26±7.44 years; 334 men, 285 women] were included. The mean hemoglobin concentration was significantly lower in the elderly who were frail (11.9 g/L in frail versus 13.1g/L in non-frail; p<0.001). In the multivariable regression models, lower hemoglobin in patients was significantly associated with frailty (adjusted odds ratio (OR) = 2.51, 95% CI:1.37, 4.60). The stratified analyses indicated that lower hemoglobin was associated with frailty among older inpatients with different characteristics. Female inpatients with lower hemoglobin had the highest risk of frailty (adjusted OR=6.43, 95%: 2.38, 17.3); there were interactions between hemoglobin and sex on the development of frailty (RERI=4.30, 95% CI=−1.41, 10.01; AP=0.67, 95% CI=0.37, 0.97;SI=4.80, 95% CI=1.22, 18.84).

Conclusions and Implications

Our study provided evidence that sex and lower hemoglobin have an interaction effect on frailty; it is suggested that clinicians may consider sex-specific strategies for the elderly to conform the concept of precision medicine.

Correlation of Biomarkers with Endoscopic Score: Ulcerative Colitis Endoscopic Index of Severity (UCEIS) in Patients with Ulcerative Colitis in Remission

Background and Objectives: Ulcerative colitis is a disease with an unpredictable evolution, often highlighted endoscopically, that is associated with persistent inflammation affecting the patient’s quality of life. An attempt was made to discover surrogate markers to evaluate the endoscopic remission of the disease in order to increase the patient’s quality of life and also their adherence to the treatment and monitoring plan. One such marker is fecal calprotectin (FC). To confirm the correlation between biomarkers and endoscopic disease activity and to define the optimal cut off value to detect clinical and endoscopic remission in a center of Romania. Materials and Methods: This was a prospective study that included 59 patients diagnosed with ulcerative colitis at the Department of Internal Medicine III, University Emergency Hospital of Bucharest. Patients had fecal calprotectin measurements and colonoscopy/rectosigmoidoscopy performed during baseline, 6 and 12 months. For endoscopic activity the Ulcerative Colitis Endoscopic Index of Severity (UCEIS) was used. Results: During the study, relapses have occurred in 35.6% of patients, the median age was 47 years (21–77). During the study, the FC measurement was significantly increased at 3 months (median, range µg/g; 715, 14–4000) and at 6 months (median, range µg/g; 650, 4.5–3000) (p ≤ 0.05). Another inflammatory biomarker studied was CRP, which showed increased values at 3 months (median, range, mg/dL; 1.86, 0.14–58.9), at 6 months (median, range, mg/dL; 2.36, 0.12–45.8) and at 9 months (median, range, mg/dL; 2, 0.12–25.9) compared to the baseline (p = 0.01). Patients with recurrence of the disease also associated an increase in the values of clinical evaluation scores (SCCAI; p = 0.00001), but also endoscopic (UCEIS; p = 0.0006) Conclusion: A relapse is associated independently with younger age, the extension of the disease (E2-E3), increased FC level, C reactive protein, hemoglobin concentration, SCCAI index and UCEIS score.

Gastrointestinal parasite infection intensity and hematological parameters in South African communal indigenous goats in relation to anemia

Aim:

The study was conducted to determine the intensity of gastrointestinal parasite (GIP) infections and hematological parameters in South African communal indigenous goats in relation to anemia.

Materials and Methods:

A total of 288 goats were randomly sampled in areas representing four agro-ecological zones. Fecal and blood samples were collected from the rectum and jugular vein, respectively, of each animal. The number of eggs per gram (EPG) and oocysts per gram (OPG) of feces and the hematological parameters were determined using the modified McMaster technique and a BC-2800Vet® automatic hematology analyzer, respectively. Data were analyzed using the repeated measures techniques of Minitab 17, modeling the covariance structure of the observed data.

Results:

Based on EPG and OPG, goats in humid zone were significantly infected (p<0.05) with strongyles, Eimeria, Moniezia, and Trichuris spp. Hematological parameters of goats in arid and humid zone were lower (p<0.05) than those in semi-arid and dry sub-humid zone. GIP infection intensities were higher (p<0.05) in young animals than in adult and suckling goats. GIP infection intensity was similar between goat sexes, while hematological parameters were higher (p<0.05) in females. Higher (p<0.05) infection intensities for strongyles (302.90 EPG) and Eimeria (216.09 EPG) were observed in winter compared to summer (strongyles: 302.90, Eimeria: 216.09 EPG). Higher (p<0.05) values for the hematological parameters were observed during summer compared to that in winter.

Conclusion:

GIP infection intensity in the winter could be associated with hypochromic and normocytic anemia which likely to affects suckling goats while in the summer could be associated with normochromic and normocytic anemia which likely to affect young goats.

Geographical ancestry affects normal hemoglobin values in high-altitude residents

Increasing the hemoglobin (Hb) concentration is a major mechanism adjusting arterial oxygen content to decreased oxygen partial pressure of inspired air at high altitude. Approximately 5% of the world's population living at altitudes higher than 1,500 m shows this adaptive mechanism. Notably, there is a wide variation in the extent of increase in Hb concentration among different populations. This short review summarizes available information on Hb concentrations of high-altitude residents living at comparable altitudes (3,500-4,500 m) in different regions of the world. An increased Hb concentration is found in all high-altitude populations. The highest mean Hb concentration was found in adult male Andean residents and in Han Chinese living at high altitude, whereas it was lowest in Ethiopians, Tibetans, and Sherpas. A lower plasma volume in Andean high-altitude natives may offer a partial explanation. Indeed, male Andean high-altitude natives have a lower plasma volume than Tibetans and Ethiopians. Moreover, Hb values were lower in adult, nonpregnant females than in males; differences between populations of different ancestry were less pronounced. Various genetic polymorphisms were detected in high-altitude residents thought to favor life in a hypoxic environment, some of which correlate with the relatively low Hb concentration in the Tibetans and Ethiopians, whereas differences in angiotensin-converting enzyme allele distribution may be related to elevated Hb in the Andeans. Taken together, these results indicate different sensitivity of oxygen dependent control of erythropoiesis or plasma volume among populations of different geographical ancestry, offering explanations for differences in the Hb concentration at high altitude.

Photoacoustic Imaging for Assessing Tissue Oxygenation Changes in Rat Hepatic Fibrosis

Chronic liver inflammation progressively evokes fibrosis and cirrhosis resulting in compromised liver function, and often leading to cancer. Early diagnosis and staging of fibrosis is crucial because the five-year survival rate of early-stage liver cancer is high. This study investigates the progression of hepatic fibrosis induced in rats following ingestion of diethylnitrosamine (DEN). Changes in oxygen saturation and hemoglobin concentration resulting from chronic inflammation were assayed longitudinally during DEN ingestion by photoacoustic imaging (PAI). Accompanying liver tissue changes were monitored simultaneously by B-mode sonographic imaging. Oxygen saturation and hemoglobin levels in the liver increased over 5 weeks and peaked at 10 weeks before decreasing at 13 weeks of DEN ingestion. The oxygenation changes were accompanied by an increase in hepatic echogenicity and coarseness in the ultrasound image. Histology at 13 weeks confirmed the development of severe fibrosis and cirrhosis. The observed increase in PA signal representing enhanced blood oxygenation is likely an inflammatory physiological response to the dietary DEN insult that increases blood flow by the development of neovasculature to supply oxygen to a fibrotic liver during the progression of hepatic fibrosis. Assessment of oxygenation by PAI may play an important role in the future assessment of hepatic fibrosis.

Measurement of the Cellular Hemoglobin Concentration by Laser Scatter Method from Excessive Lipemic Sample: CASE REPORT

A 33-month old female child presented at a pediatric clinic with acute tonsillitis, and it was subsequently discovered that she had familial hyperlipidemia. Measurement of the patient's whole blood tests was performed by a multiparameter automated hematology analyzer, the CELLDYN Ruby System® (Abbott, Lake Forest, USA) using venous blood extracted from a tube containing 3.0 mL of EDTA. Although her hematocrit levels were within normal limits, the hemoglobin (Hgb) level, mean corpuscular volume (MCH) and mean corpuscular Hgb concentration (MCHC) could not be determined using the spectrophotometric method. The results of these tests could not be measured when repeated using dilution. When the sample was left to rest for several minutes, it was observed to be excessively lipemic. The measurements were repeated using the Alinity HQ Analyzer® (Abbott), which determines Hgb concentration using laser scatter and spectrophotometry. Hgb cellular concentration was incorrectly measured as being 21.9 mg/dL using routine spectrophotometry (denoted by a flag indicating Hgb interference) and correctly found to be 10.8 mg/dL. Thus, in samples of excessive lipemia, Hgb, MCH, and MCHC levels cannot be measured accurately using spectrophotometry. Hematology analyzers that can measure cellular hemoglobin (cHGB) and average erythrocyte hemoglobin concentration (cHCM) by laser scatter method may be recommended when analyzing a blood sample that contains excessive lipemia.

The Impact of Nutrition-Specific and Nutrition-Sensitive Interventions on Hemoglobin Concentrations and Anemia: A Meta-review of Systematic Reviews

Anemia is a multifactorial condition arising from inadequate nutrition, infection, chronic disease, and genetic-related etiologies. Our aim was to assess the impact of nutrition-sensitive and nutrition-specific interventions on hemoglobin (Hb) concentrations and anemia to inform the prioritization and scale-up of interventions to address the multiple causes of anemia. We performed a meta-review synthesis of information by searching multiple databases for reviews published between 1990 and 2017 and used standard methods for conducting a meta-review of reviews, including double independent screening, extraction, and quality assessment. Quantitative pooling and narrative syntheses were used to summarize information. Hb concentration and anemia outcomes were pooled in specific population groups (children aged <5 y, school-age children, and pregnant women). Methodological quality of the systematic reviews was assessed using Assessing the Methodological Quality of Systematic Reviews (AMSTAR) criteria. Of the 15,444 records screened, we identified 118 systematic reviews that met inclusion criteria. Reviews focused on nutrition-specific interventions (96%). Daily and intermittent iron supplementation, micronutrient powders, malaria treatment, use of insecticide-treated nets (ITNs), and delayed cord clamping were associated with increased Hb concentration in children aged <5 y. Among children older than 5 y, daily and intermittent iron supplementation and deworming, and in pregnant women, daily iron-folic acid supplementation, use of ITNs, and delayed cord clamping, were associated with increased Hb concentration. Similar results were obtained for the reduced risk of anemia outcome. This meta-review suggests the importance of nutrition-specific interventions for anemia and highlights the lack of evidence to understand the influence of nutrition-sensitive and multifaceted interventions on the condition.

Effects of Norepinephrine, Propofol, and Hemoglobin Concentration on Dynamic Measurements of Cerebrovascular Reactivity in Acute Brain Injury

Effects of treatment-associated variables on cerebrovascular autoregulation (CA) in acute brain injury patients remain unclear. As deficient CA is associated with worse outcomes and ideas about CA-steered management are emerging, this question is relevant. We investigated effects of norepinephrine and propofol infusion rates and hemoglobin concentration on dynamic measurements of cerebrovascular reactivity as surrogate for CA. A retrospective analysis of 91 traumatic brain injury (TBI) and 13 stroke patients admitted to the intensive care unit (ICU) of the Leuven University Hospitals was performed. Low-resolution autoregulation index (LAx) and high-frequency pressure reactivity index (PRx) were calculated as measurements of cerebrovascular reactivity. Data was binned into 5-, 15-, and 60-min intervals. Bivariate time-series analysis using lagged cross-correlations were calculated after pre-whitening and differencing. Linear mixed models evaluated effects of age, gender, cardiovascular risk, brain comorbidity, Glasgow Coma Scale (GCS), pupil reactivity, and type of injury. Median dose of norepinephrine, propofol and hemoglobin concentration was 7.8 μg/kg/h (Q1 3.6-Q3 13.8), 3 mg/kg/h (Q1 1.9-Q3 4.3), and 9.2 g·dL^-1 (Q1 8.2-Q3 10.5), respectively. Mean cross-correlations for 24 lags were close to zero and not significant for all variables. No significant differences as function of age, gender, cardiovascular risk, brain comorbidity, GCS, pupil reactivity, and type of injury were found. Dynamic intracranial pressure-based measurements of cerebrovascular reactivity in acute brain injured patients are not affected by gradually adjusted norepinephrine or propofol infusion rates or slow changes in hemoglobin concentration within the typical ranges during ICU admission. Future trials on cerebrovascular reactivity-steered management and treatment of CA impairment may not have to take these variables into account.

Hemoglobin Concentration May Affect the Effect of Atorvastin on Chronic Subdural Hematoma After Burr-Hole Drainage at High Altitude

Objective

Chronic subdural hematoma (CSDH) is a common disease. Atorvastatin calcium can increase CSDH absorption. However, whether atorvastatin can increase hematoma absorption and reduce recurrence at high altitudes is not clear.

Methods

After burr-hole drainage, CSDH patients were divided into an atorvastatin group and a control group. Follow-up computed tomography (CT) was performed on day 1, months 1, 2, and 3 after surgery. Then, the recurrence rate, poor therapeutic effect, time to recurrence, poor surgical result, recurrence with operation, CSDH volume, and Markwalder grading scale score (MGSS) were calculated, and related risk factors were analyzed.

Results

The non-recurrent and recurrent patients in the control group differed significantly in terms of the hemoglobin concentration (HB) [176.24 ± 16.43 vs. 194.25 ± 12.34 (g/L), p < 0.01], CT value [41.92 ± 10.76 vs. 34.12 ± 8.78 (Hu), p < 0.01], and low-density time [3.88 ± 1.04 vs. 5.50 ± 0.87 (d), p < 0.01]. The non-recurrent and recurrent patients in the atorvastatin group differed significantly in terms of the HB [172.66 ± 16.41 vs. 190.45 ± 10.23 (g/L), p < 0.01], CT value [38.91 ± 7.16 vs. 29.50 ± 8.61 (Hu), p < 0.01], and mixed [2 vs. 4 (n), p < 0.05] and low-density time [4.09 ± 0.75 vs. 5.45 ± 1.12 (d), p < 0.01]. The logistic regression analysis showed that HB [odds ratio, 1.14; 95% confidence interval (CI), 1.04–1.25 in the control group, odds ratio, 1.13; 95% CI, 1.03–1.23 in the atorvastatin group] and low-density time (odds ratio, 3.53; 95% CI, 1.42–8.74 in the control group, odds ratio, 2.53; 95% CI, 1.10–5.80 in the atorvastatin group) were possible risk factors for the two groups. The receiver operating characteristic curves showed that the area under the receiver operating characteristic curve values for the HB, CT value (Hu), and low-density time were 0.812, 0.702, and 0.755 for all subjects; 0.812, 0.719, and 0.790 for the control group; and 0.807, 0.682, and 0.756 for the atorvastatin group, respectively. The postoperative follow-up results showed that there was no significant difference in the recurrence rate, poor therapeutic effect, time to recurrence, poor surgical result, recurrence with operation, CSDH volume, or MGSS between the two groups.

Conclusion

The effect of atorvastatin was not significant after the operation. The risk factors for CSDH recurrence were the HB and low-density time. The HB was the most specific and sensitive predictor of CSDH recurrence.

A Novel Smart Assistance System for Blood Vessel Approaching: A Technical Report Based on Oximetry

In clinical practice, the catheter has to be placed at an accurate position during anesthesia administration. However, effectively guiding the catheter to the accurate position in deeper tissues can be difficult for an inexperienced practitioner. We aimed to address the current issues associated with catheter placement using a novel smart assistance system for blood vessel catheter placement. We used a hollow introducer needle embedded with dual wavelength (690 and 850 nm) optical fibers to advance the tip into the subclavian vessels in anesthetized piglets. The results showed average optical density changes, and the difference between the absorption spectra and hemoglobin concentrations of different tissue components effectively identified different tissues (p < 0.05). The radial basis function neural network (RBFNN) technique was applied to distinguish tissue components (the F-measure value and accuracy were 93.02% and 94%, respectively). Finally, animal experiments were designed to validate the performance of the proposed system. Using this system based on oximetry, we easily navigated the needle tip to the target vessel. Based on the experimental results, the proposed system could effectively distinguish different tissue layers of the animals.

Prioritizing natural-selection signals from the deep-sequencing genomic data suggests multi-variant adaptation in Tibetan highlanders

Human genetic adaptation to high altitudes (>2500 m) has been extensively studied over the last few years, but few functional adaptive genetic variants have been identified, largely owing to the lack of deep-genome sequencing data available to previous studies. Here, we build a list of putative adaptive variants, including 63 missense, 7 loss-of-function, 1,298 evolutionarily conserved variants and 509 expression quantitative traits loci. Notably, the top signal of selection is located in TMEM247, a transmembrane protein-coding gene. The Tibetan version of TMEM247 harbors one high-frequency (76.3%) missense variant, rs116983452 (c.248C > T; p.Ala83Val), with the T allele derived from archaic ancestry and carried by >94% of Tibetans but absent or in low frequencies (<3%) in non-Tibetan populations. The rs116983452-T is strongly and positively correlated with altitude and significantly associated with reduced hemoglobin concentration (p = 5.78 × 10-5), red blood cell count (p = 5.72 × 10-7) and hematocrit (p = 2.57 × 10-6). In particular, TMEM247-rs116983452 shows greater effect size and better predicts the phenotypic outcome than any EPAS1 variants in association with adaptive traits in Tibetans. Modeling the interaction between TMEM247-rs116983452 and EPAS1 variants indicates weak but statistically significant epistatic effects. Our results support that multiple variants may jointly deliver the fitness of the Tibetans on the plateau, where a complex model is needed to elucidate the adaptive evolution mechanism.

Quantitative flow ratio and fractional flow reserve mismatch - clinical and biochemical predictors of measurement discrepancy

Introduction

Fractional flow reserve (FFR) is the gold standard for functional assessment of intermediate lesions. However, assessing a stenosis with pressure wire prolongs the procedure, increases costs and carries a risk of procedure-related adverse events. Quantitative flow ratio (QFR) is a wire-free method for detection of significant ischemia based on 3D reconstruction of angiographic images and TIMI frame count.

Aim

To evaluate the influence of laboratory and clinical variables on QFR-FFR mismatch.

Material and methods

We retrospectively computed QFR (Medis Suite XA/QAngio XA 3D/QFR, Medis/Netherlands) in suitable cases with corresponding FFR (PressureWire, Abbott, US). Uni-/multivariate analysis was performed to identify clinical and biochemical predictors of QFR-FFR mismatch.

Results

Two hundred six lesions (196 patients, 76% male, mean age: 66.4 ±10.1 years) were included. Chronic kidney disease (CKD) and insulin-treated diabetes mellitus (ITDM) were associated with significantly larger differences between QFR and FFR values (-0.062 ±0.031 vs. -0.025 ±0.068; p = 0.027 and -0.059 ±0.07 vs. -0.027 ±0.074; p = 0.039; respectively). CKD was associated with a decrease of diagnostic efficiency (AUC = 0.67, 95% CI: 0.46-0.88 vs. AUC = 0.89, 95% CI: 0.84-0.94, p = 0.05). For biochemical variables only weak Spearman correlations were identified for hemoglobin concentration (r = -0.18) and hematocrit levels (r = -0.18).

Conclusions

CKD may impair the QFR diagnostic accuracy. Larger, prospective studies are needed to further explore this potential relationship.

Noninvasive evaluation of hemodynamics and light scattering property during two-stage mouse cutaneous carcinogenesis based on multispectral diffuse reflectance images at isosbestic wavelengths of hemoglobin

We investigate a multispectral imaging method to evaluate spatiotemporal changes in both cutaneous hemoglobin concentration and light scattering parameter in mouse skin through diffuse reflectance spectroscopy using the reflectance images acquired at isosbestic wavelengths of hemoglobin (420, 450, 500, and 585 nm). In the proposed approach, Monte Carlo simulation-based empirical formulas are introduced to extract the scattering power b representing the wavelength dependence of light scattering spectrum of skin tissue, as well as the total hemoglobin concentration Cth in dermal vasculatures. The use of isosbestic wavelengths of hemoglobin enables the values of Cth and b to be estimated independently of the oxygenation of hemoglobin. Experiments using in vivo mice two-stage chemical carcinogenesis model are performed to confirm the feasibility of the proposed method for evaluating the changes in cutaneous vasculatures and tissue morphology during tumor initiation, promotion, and progression processes. The experimental results reveal that the changes in scattering power b of back skin are significantly reduced and followed by the increase in total hemoglobin concentration Cth in the carcinogenesis mice group, which indicates morphological changes in skin tissue such as edema and cell swelling caused by tumor promotion and successive angiogenesis along with tumor progression. The results suggest that the potential of the present method to detect cutaneous carcinogenesis in an early stage and monitor physiological changes during promotion and progression process of nonmelanoma tumors.

Depth dependence of coherent hemodynamics in the human head

We report a near-infrared spectroscopy (NIRS) study of coherent hemodynamic oscillations measured on the human forehead at multiple source-detector distances (1 to 4 cm). The physiological source of the coherent hemodynamics is arterial blood pressure oscillations at a frequency of 0.1 Hz, induced by cyclic inflation (to a pressure of 200 mmHg) and deflation of two thigh cuffs wrapped around the subject's thighs. To interpret our results, we use a recently developed hemodynamic model and a phasor representation of the oscillations of oxyhemoglobin, deoxyhemoglobin, and total hemoglobin concentrations in the tissue (phasors O, D, and T, respectively). The increase in the phase angle between D and O at larger source-detector separations is assigned to greater flow versus volume contributions and to a stronger blood flow autoregulation in deeper tissue (brain cortex) with respect to superficial tissue (scalp and skull). The relatively constant phase lag of T versus arterial blood pressure oscillations at all source-detector distances was assigned to competing effects from stronger autoregulation and smaller arterial-to-venous contributions in deeper tissue with respect to superficial tissue. We demonstrate the application of a hemodynamic model to interpret coherent hemodynamics measured with NIRS and to assess the different nature of shallow (extracerebral) versus deep (cerebral) tissue hemodynamics.

Increase of frontal cerebral blood volume during transcranial magnetic stimulation in depression is related to treatment effectiveness: A pilot study with near-infrared spectroscopy

AIM

Alterations of cerebral blood flow have been reported in studies of depression treated by transcranial magnetic stimulation (TMS). However, the relation between these changes in activity during stimulation and the effectiveness of TMS is not known. The aim of this study was to determine whether changes in frontal cerebral blood volume measured as frontal hemoglobin concentration (fHbC) during TMS are correlated with clinical outcomes of treatment.

METHODS

Fifteen drug-resistant patients with depression underwent a standard treatment regimen of TMS to the left dorsolateral prefrontal cortex. We recorded fHbC during stimulation at the start and end of the TMS treatment series using near-infrared spectroscopy. Symptom severity was determined using the Montgomery-Åsberg Depression Rating Scale.

RESULTS

At the start of the TMS series, fHbC increased during stimulation in a majority of patients with no relation to symptom severity. However, at the end of the series, fHbC increase during stimulation was negatively correlated with the Montgomery-Åsberg Depression Rating Scale score and positively with the score reduction. Patients showing a decreasing response of fHbC during TMS at the end of the series experienced less clinical improvement.

CONCLUSION

These results suggest that the maintenance of frontal activation during stimulation in the course of TMS series is related to the effectiveness in the treatment of depression. Measurement of fHbC during stimulation is informative in the clinical use of TMS.

[The research of hemoglobin mass on athletic biological passport for blood doping detection]

OBJECTIVE

To research the changes of blood parameters on different time points after micro-rHuEPO injection on young men and hope to provide evidences for Athletic Biological Passport (ABP) using in the detection of blood doping.

METHODS

Fourteen health young men were injected with micro-rHuEPO for 7 weeks, twice per one week.The subjects were treated with ferralia 105 mg every day during the injections.The control group was administrated with the same volume of saline solution injection and placebo 105 mg.The blood parameters (red blood cell, hemoglobin, reticulocyte, total hemoglobin, plasma volume, etc) were tested 11 times (7 days before the first injection, 3, 10, 17, 24, 31, 38 and 45 days after the first injection, 1, 2 and 3 weeks post the seventh week of last injection).By analyzed these total and concentration parameters, hope to know the effective of two kinds of parameters on ABP.

RESULTS

The levels of RBC and[Hb] were increased sharply after two weeks of injection and reached the peak in 5-6 weeks (9-10%, P<0.01).It sustained till 3 weeks after the last injection.Total hemoglobin was increased significantly during the whole procedure of injections and reached the peak in week 5 (10%, P<0.01) till 1 week after the last injection.Red blood cell volume was increased with the EPO injection and reached the peak in week 5 (P<0.01), but blood volume wasn't increased significantly.Plasma volume was decreased with EPO injection and it was hemoconcentration.

CONCLUSIONS

It can enhance the total and concentration parameters through 7-week micro-rHuEPO injections and the total haemoglobin is more sensitive.So tHb can be used to detect blood doping in ABP.At the end of the last injection, the total blood parameters, such as the total hemoglobin, returned to normal, while the concentration index remained highly, possibly as a result of blood concentration.

Dietary Intake, Prevalence, and the Effect of Anemia on Various Morphophysiological Variables of Postmenopausal Women of North India

CONTEXT

Anemia has a high prevalence among postmenopausal Indian females.

AIM AND OBJECTIVE

The aim of this study was to evaluate dietary intake, prevalence, and the effect of anemia on various morphophysiological variables among postmenopausal women.

SETTING AND DESIGN

This was a community-based sample survey.

MATERIALS AND METHODS

A total of 250 postmenopausal women aged 45-80 years from various parts of North India participated in the study. Anthropometric measurements, hemoglobin concentration, and bone mineral density (BMD) (using dual-energy X-ray absorptiometry) of each participant were assessed. A 24-h dietary recall method for three consecutive days was employed.

STATISTICAL ANALYSIS

The Statistical Package for the Social Sciences version 20 was used for statistical considerations.

RESULTS

An age-associated decline in the mean values of hemoglobin concentration and the prevalence of anemia was reported to be 85.2% among postmenopausal women. Anemic women were lighter and had lesser circumferential measurements as well as lower BMD than their nonanemic counterparts. The intake of nutrients such as protein, calcium, and iron and energy was lower among anemic women than nonanemic women. Binary logistic regression analysis identified age (odds ratio = 1.04, 95% confidence interval = 1.00-1.09)* as the possible predictor of anemia.

CONCLUSIONS

Anemia was not only the result of aging process but also inadequate and unbalanced dietary intake.

Transdermal Optical Imaging Reveal Basal Stress via Heart Rate Variability Analysis: A Novel Methodology Comparable to Electrocardiography

The present study examined the validity of a novel physiological measurement technology called transdermal optical imaging (TOI) technology at assessing basal stress. This technology conveniently, contactlessly, and remotely measures facial blood flow changes using a conventional digital video camera. We compared data from TOI against the pulse data collected from the FDA approved BIOPAC system. One hundred thirty-six healthy adults participated in the study. We found that TOI measurements of heart rate and heart rate variability (HRV), which reflects basal stress, corresponded strongly to those obtained from BIOPAC. These findings indicate that TOI technology is a viable method to monitor heart rate and HRV not only accurately but also conveniently, contactlessly, and remotely. Further, measures of HRV obtained via TOI serves as a valid index of basal stress. Potential applications of this technology in psychological research and other fields are discussed.

Measures of Blood Hemoglobin and Hematocrit During Cardiac Surgery: Comparison of Three Point-of-Care Devices

OBJECTIVE

The primary objective was to compare I-Stat, HemoCue, and RapidLab in measurements of the hemoglobin concentration during cardiac surgeries using cardiopulmonary bypass.

DESIGN

Prospective analysis.

SETTING

Single-center, academic, tertiary care cardiovascular center.

PARTICIPANTS

Thirty-four consecutive patients undergoing cardiac surgery requiring cardiopulmonary bypass.

INTERVENTIONS

Blood samples have been collected intraoperatively, and the hemoglobin concentration in each sample was measured, or calculated, simultaneously by the 3 point-of-care devices, HemoCue, RapidLab, and I-Stat.

MEASUREMENTS AND MAIN RESULTS

Correlation coefficients from the regression analysis for HemoCue versus I-Stat, RapidLab versus HemoCue, and RapidLab versus I-Stat were 0.89, 0.96, and 0.88, respectively. Results of the Bland-Altman analysis of the hemoglobin concentration measurements for each device against one another (Fig 1) were as follows: RapidLab versus I-Stat (bias 0.42; 95% confidence interval [CI], -1.05 to 1.89), I-Stat versus HemoCue (bias 0.23; 95% CI, -1.14 to 1.59), and RapidLab versus HemoCue (bias 0.65; 95% CI, -0.17 to 1.47). It appears that I-Stat slightly underestimated the concentration of hemoglobin when compared with both RapidLab and HemoCue. The results of Bland-Altman analysis of each device to a mean Z value (Fig 2) were as follows: RapidLab versus Z (bias 0.36; 95% CI, -0.29 to 1.01), I-Stat versus Z (bias -0.07; CI -0.97 to 0.84), and HemoCue versus Z (bias -0.29; 95% CI, -0.86 to 0.28). Based on the 174 paired samples used for the Pearson moment analysis, the R² values for I-Stat versus HemoCue, I-Stat versus RapidLab, and RapidLab versus HemoCue were 0.79, 0.80, and 0.87, respectively CONCLUSIONS: These data support the interchangeability of these 3 devices for the intermittent intraoperative point-of-care assessment of hemoglobin concentrations in cardiac surgery patients. It is important, however, to consider the possible pitfalls associated with each device when making a clinical decision to transfuse.

Novel diffuse optics system for continuous tissue viability monitoring - extended recovery in vivo testing in a porcine flap model

In reconstructive surgery, tissue perfusion/vessel patency is critical to the success of microvascular free tissue flaps. Early detection of flap failure secondary to compromise of vascular perfusion would significantly increase the chances of flap salvage. We have developed a compact, clinically-compatible monitoring system to enable automated, minimally-invasive, continuous, and quantitative assessment of flap viability/perfusion. We tested the system's continuous monitoring capability during extended non-recovery surgery using an in vivo porcine free flap model. Initial results indicated that the system could assess flap viability/perfusion in a quantitative and continuous manner. With proven performance, the compact form constructed with cost-effective components would make this system suitable for clinical translation.

Update on Phototherapy in Jaundiced Neonates

BACKGROUND

Even relatively low serum bilirubin concentrations can cause neurodevelopmental impairment in extremely low birth weight (EBWL) infants, while sequelae from hyperbilirubinemia in late preterm and term infants are rare and occur only at very high serum bilirubin levels. Phototherapy is the current treatment of choice.

OBJECTIVE

To present an update on the most important issues involved in phototherapy for jaundiced infants.

RESULTS

Light absorption by bilirubin in the skin transforms the native Z,Z-bilirubin to conformational photoisomers Z,E-bilirubin and E,Z-bilirubin and structural photoisomers E,Z-lumirubin and E,E-lumirubin. Formation and excretion of Z,E-bilirubin and E,Z-lumirubin are both important routes of elimination of bilirubin through bile and urine, although the precise contributions of the various photoisomers to the overall elimination of bilirubin are unknown. It appears that the photoisomers of bilirubin are predominantly formed in the plasma, and the rate of formation is affected by the hemoglobin concentration. Phototherapy lights with an emission spectrum of 460-490 nm provide the most efficient bilirubin-reducing light. LEDs should replace fluorescent tubes and halogen spotlights as the preferred light sources. Recent data raise concerns that sick ELBW infants under prolonged phototherapy may have an increased risk of death, though survivors may benefit from reduced rates of neurodevelopmental impairment. Comparison of the efficacy of cycled vs. continuous phototherapy has given divergent results. Changing the infant's position does not increase the efficacy of phototherapy.

CONCLUSION

During the last decade, we have made progress in our understanding of how and where phototherapy works and in its practical applications.

Load management in elite German distance runners during 3-weeks of high-altitude training

There is a debate on the optimal way of monitoring training loads in elite endurance athletes especially during altitude training camps. In this case report, including nine members of the German national middle distance running team, we describe a practical approach to monitor the psychobiological stress markers during 21 days of altitude training (~2100 m above sea-level) to estimate the training load and to control muscle damage, fatigue, and/or chronic overreaching. Daily examination included: oxygen saturation of hemoglobin, resting heart rate, body mass, body and sleep perception, capillary blood concentration of creatine kinase. Every other day, venous serum concentration of blood urea nitrogen, venous blood concentration of hemoglobin, hematocrit, red and white blood cell were measured. If two or more of the above-mentioned stress markers were beyond or beneath the athlete's normal individual range, the training load of the subsequent training session was reduced. Running speed at 3 mmol L(-1) blood lactate (V3) improved and no athlete showed any signs of underperformance, chronic muscle damage, decrease body and sleep perception as well as activated inflammatory process during the 21 days. The dense screening of biomarkers in the present case study may stimulate further research to identify candidate markers for load monitoring in elite middle- and long-distance runners during a training camp at altitude.

The effect of methanolic extract of Buchanania lanzan Spreng seeds on hematological indices

Objective:

The objective of the current study was carried out to investigate the effects of methanolic extract of Buchanania lanzan Spreng seeds on hematological indices.

Materials and Methods:

Eighteen male albino Wistar rats were divided into three groups, six in each. Group I animals received distilled water, Group II and III were treated with an oral dose of 1000 mg oil/kg and 2000 mg oil/kg of extract, respectively, for 7 days. At the end of the study, blood was collected and evaluated for packed cell volume (PCV), hemoglobin (Hb) concentration, and red blood cell (RBC) and white blood cell (WBC) counts.

Results:

There was a significant dose-dependent increase in the hematological indices such as PCV, Hb, RBC, and WBC count in the treatment group.

Conclusions:

The improvement of PCV, Hb, and RBC values is an indication of the anti-anemic effect which may be due to the stimulation of RBC production in bone marrow. Further, stimulated production of WBC could be as a result of possible stimulus of the immune system. Hence, this study confirms that the extract of B. lanzan could be useful for the treatment of anemia.

Reproduction and survival in the city: which fitness components drive urban colonization in a reed-nesting waterbird?

Processes of adaptation to urban environments are well described for relatively few avian taxa, mainly passerines, but selective forces responsible for urban colonization in ecologically different groups of birds remain mostly unrecognized. The aim of this article is to identify drivers of recent urban colonization (Łódź, central Poland) by a reed-nesting waterbird, the Eurasian coot Fulica atra. Urban colonizers were found to adopt a distinct reproductive strategy by maximizing the number of offspring (carryover effects of higher clutch size), whereas suburban individuals invested more in the quality of the progeny (higher egg volume), which could reflect differences in predatory pressure between 2 habitats. In fact, reduced predation rate was strongly suggested by elevated hatching success in highly urbanized areas, where probability of hatching at least 1 chick was higher by 30% than in suburban natural-like habitats. Coots nesting in highly urbanized landscape had considerably higher annual reproductive success in comparison to suburban pairs, and the difference was 4-fold between the most and least urbanized areas. There was also a constant increase in size-adjusted body mass and hemoglobin concentration of breeding coots from the suburbs to the city centre. Urban colonization yielded no survival benefits for adult birds and urban individuals showed higher site fidelity than suburban conspecifics. The results suggest that the recent urban colonization by Eurasian coots was primary driven by considerable reproductive benefits which may be primarily attributed to: (1) reduced predation resulting from an exclusion of most native predators from highly urbanized zones; (2) increased condition of urban-dwelling birds resulting from enhanced food availability.

Quantitative theory for the longitudinal relaxation time of blood water

PURPOSE

To propose and evaluate a model for the blood water T1 that takes into account the effects of hematocrit fraction, oxygenation fraction, erythrocyte hemoglobin concentration, methemoglobin fraction, and plasma albumin concentration.

METHODS

Whole blood and lysed blood T1 data were acquired at magnetic fields of 3 Tesla (T), 7T, 9.4T, and 11.7T using inversion-recovery measurements and a home-built blood circulation system for maintaining physiological conditions. A quantitative model was derived based on multivariable fitting of this data.

RESULTS

Fitting of the model to the data allowed determination of the different parameters describing the blood water T1 such as those for the diamagnetic and paramagnetic effects of albumin and hemoglobin, and the contribution of methemoglobin. The model correctly predicts blood T1 at multiple fields, as verified by comparison with existing literature.

CONCLUSION

The model provides physical and physiological parameters describing the effects of hematocrit fraction, oxygenation, hemoglobin concentration, methemoglobin fraction, and albumin concentration on blood water T1 . It can be used to predict blood T1 at multiple fields. Magn Reson Med 76:270-281, 2016. © 2015 Wiley Periodicals, Inc.

The Prefrontal Cortex Activity and Psychological Effects of Viewing Forest Landscapes in Autumn Season

Recently reported research indicate that forest environments have physiological and psychological relaxing effects compared to urban environments. However, some researchers claim that the stress of the subjects from being watched by others during measurements can affect the measurement result in urban experiments conducted in the center of a street. The present study was conducted to determine whether forest environments have physiological and psychological relaxing effects, using comparison of viewing a forest area with viewing an urban area from the roof of an urban building without being watched by others. Near-infrared spectroscopy (NIRS) measurement was performed on subjects while they viewed scenery for 15 min at each experimental site (urban and forest areas). Subjective assessments were performed after the NIRS measurement was complete. Total hemoglobin and oxyhemoglobin concentrations were significantly lower in the forest area than in the urban area. For semantic differential in subjective assessments, feelings of “comfortable”, “natural”, and “soothed” were significantly higher in the forest area than in the urban area, and for profile of mood states, negative emotions were significantly lower in the forest area than in the urban area. The results of physiological and psychological measurements show that viewing the forest enabled effective relaxation.

Reduction of V̇O2 slow component by priming exercise: novel mechanistic insights from time-resolved near-infrared spectroscopy

Novel time-resolved near-infrared spectroscopy (TR-NIRS), with adipose tissue thickness correction, was used to test the hypotheses that heavy priming exercise reduces the V̇_O2 slow component (V̇_O2SC) (1) by elevating microvascular [Hb] volume at multiple sites within the quadriceps femoris (2) rather than reducing the heterogeneity of muscle deoxygenation kinetics. Twelve subjects completed two 6-min bouts of heavy work rate exercise, separated by 6 min of unloaded cycling. Priming exercise induced faster overall V̇_O2 kinetics consequent to a substantial reduction in the V̇_O2SC (0.27 ± 0.12 vs. 0.11 ± 0.09 L·min⁻¹, P < 0.05) with an unchanged primary V̇_O2 time constant. An increased baseline for the primed bout [total (Hb + Mb)] (197.5 ± 21.6 vs. 210.7 ± 22.5 μmol L⁻¹, P < 0.01), reflecting increased microvascular [Hb] volume, correlated significantly with the V̇_O2SC reduction. At multiple sites within the quadriceps femoris, priming exercise reduced the baseline and slowed the increase in [deoxy (Hb + Mb)]. Changes in the intersite coefficient of variation in the time delay and time constant of [deoxy (Hb + Mb)] during the second bout were not correlated with the V̇_O2SC reduction. These results support a mechanistic link between priming exercise-induced increase in muscle [Hb] volume and the reduced V̇_O2SC that serves to speed overall V̇_O2 kinetics. However, reduction in the heterogeneity of muscle deoxygenation kinetics does not appear to be an obligatory feature of the priming response.

'Sepsis-related anemia' is absent at hospital presentation; a retrospective cohort analysis

BACKGROUND

Anemia is a common feature during sepsis that occurs due to iatrogenic blood loss, depression of serum iron levels and erythropoietin production, and a decreased lifespan of erythrocytes. However, these mechanisms are unlikely to play a role in anemia at the start of sepsis. Moreover, sequestration of fluids, renal failure and increase of intravascular space may additionally influence the change in hemoglobin concentration during intravenous fluid administration in the acute phase of sepsis.

METHODS

In this retrospective study, patients who were admitted acutely to the Intensive Care Unit (ICU) were included. Patients who fulfilled the international criteria for severe sepsis or septic shock were included in the sepsis group (S-group). The remaining patients were allocated to the control group (C-group). Laboratory data from blood samples taken at first presentation to the hospital and at admission to the ICU, the amount of intravenous fluid administration and length of stay in the emergency department were collected and tested for significant differences between groups.

RESULTS

The difference in hemoglobin concentration between the S-group (n = 296) and C-group (n = 320) at first presentation in hospital was not significant (8.8 ± 1.2 versus 8.9 ± 1.2 mmol/l, respectively, p = 0.07). The reduction in hemoglobin concentration from the first presentation at the emergency department to ICU admission was significantly greater in the S-group compared to the C-group (1 [0.5-1.7] versus 0.5 [0.1-1.1] mmol/l, (p < 0.001)). Spearman rho correlation coefficients between the reduction in hemoglobin concentration and the amount of intravenous fluids administered or the creatinine level in the emergency department were significant (0.3 and 0.4, respectively, p < 0.001). In a multivariate regression analysis, creatinine, the amount of fluid administration and the presence of sepsis remained independently associated.

CONCLUSIONS

Prior to in-hospital intravenous fluid administration, there is no significant difference in hemoglobin concentration between acute septic patients and acutely ill controls. Within several hours after hospital admission, there is a significant reduction in hemoglobin concentration, not only associated with the amount of intravenous fluids administered and the creatinine level, but also independently with sepsis itself.

A simple, fast correction method of triglyceride interference in blood hemoglobin automated measurement

BACKGROUND

To establish a reliable correction method for automated hemoglobin (HGB) measurement by minimizing the interference from blood high triglyceride (TG).

METHODS

Fifty whole blood samples and 50 plasma samples containing variable TG concentrations were used to determine the centrifugation speed and time. Complete blood cell counts (CBCs) were performed by an automated hematology analyzer for 102 blood samples, in which high-level TG were artificially added. The same blood samples were centrifuged at low -speed to separate the plasma from blood cells. Then the plasma was analyzed by the same analyzer. By using the two CBC results, a correction formula was established to calculate the corrected HGB, mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC) values. Comparisons were also made of HGB, MCH, and MCHC values before and after correction of in-patient individuals who received intralipid and developed lipemia.

RESULTS

The percentage differences between the corrected and true values of HGB, MCH and MCHC were -0.28%, 0.06%, and -0.31%, respectively. The correlation coefficients of corrected values versus true values of HGB, MCH, and MCHC were 0.989, 0.935, and 0.717, respectively. This correction method was also effective for native lipemic samples.

CONCLUSION

High blood TG level can cause blood turbidity and erroneously high HGB results by hematology analyzers commonly used in clinical laboratories. Adding a simple step of low-speed centrifugation and measurement of HGB in the plasma fraction allows a quick correction of HGB measurement in lipemic blood samples.

Hemoglobin parameters from diffuse reflectance data

Tissue vasculature is altered when cancer develops. Consequently, noninvasive methods of monitoring blood vessel size, density, and oxygenation would be valuable. Simple spectroscopy employing fiber optic probes to measure backscattering can potentially determine hemoglobin parameters. However, heterogeneity of blood distribution, the dependence of the tissue-volume-sampled on scattering and absorption, and the potential compression of tissue all hinder the accurate determination of hemoglobin parameters. We address each of these issues. A simple derivation of a correction factor for the absorption coefficient, μa, is presented. This correction factor depends not only on the vessel size, as others have shown, but also on the density of blood vessels. Monte Carlo simulations were used to determine the dependence of an effective pathlength of light through tissue which is parameterized as a ninth-order polynomial function of μa. The hemoglobin bands of backscattering spectra of cervical tissue are fit using these expressions to obtain effective blood vessel size and density, tissue hemoglobin concentration, and oxygenation. Hemoglobin concentration and vessel density were found to depend on the pressure applied during in vivo acquisition of the spectra. It is also shown that determined vessel size depends on the blood hemoglobin concentration used.

The pre-transplant anemic condition is independent of long-term outcome in living-related kidney transplantation

The relationship between pre-transplant Hemoglobin (Hb) concentration and long-term outcome of living-related kidney transplantation is far from well addressed. A retrospective cohort study was conducted by reviewing the medical profile of the patients who received living-related kidney transplantations at our center from January 2006 to January 2013. Patients were divided into two groups: high Hb group (≥10 g/dL) and low Hb group (<10 g/dL). Cox regression model was utilized to analyze the effect of pre-transplant hemoglobin concentration on the patient and graft survival. About 422 patients were of Hb level <10 g/dL (78.30 ± 14.18 g/dL), 280 were >10 g/dL (116.2 ± 14.43 g/dL) (p < 0.001). In a follow-up of 35.34 ± 18.12 months, we did not find any difference in serum creatinine between the two groups. Low Hb concentration is not associated with increased risk of developing DGF (HR = 1.186, 95% CI: 0.53-2.654), acute rejection (HR = 1.338, 95% CI: 0.919-1.947), overall infection (HR = 1.263, 95% CI: 0.847-1.885) nor perioperational infection (HR = 1.019, 95% CI: 0.513-2.026). Though we detected a trend that low Hb level group were of higher incidence of patient death and graft failure, the two groups did not differ significantly (2.38% vs. 0.71%, p = 0.096; and 4.04% vs. 2.14%, p = 0.165, respectively). Cox regression model revealed that pre-transplant Hb level <10 g/dL was independent of increased overall mortality (HR = 3.379; 95% CI: 0.706-17.172) and increased death censored allograft failure risk (HR = 1.556; 95% CI: 0.595-4.069). Pre-transplant Hb concentration <10 g/dL is independent of poor long-term outcome of living-related kidney transplantation.

Effect of facility-level hemoglobin concentration on dialysis patient risk of transfusion

BACKGROUND

Changes in anemia management practices due to concerns about erythropoiesis-stimulating agent safety and Medicare payment changes may increase patient risk of transfusion. We examined anemia management trends in hemodialysis patients and risk of red blood cell (RBC) transfusion according to dialysis facility-level hemoglobin concentration.

STUDY DESIGN

Retrospective follow-up study; 6-month study period (January to June), 3-month exposure/follow-up.

SETTING & PARTICIPANTS

For each year in 2007-2011, annual cohorts of point-prevalent Medicare primary payer patients receiving hemodialysis on January 1 with one or more hemoglobin measurements during the study period. Annual cohorts averaged 170,000 patients, with 130,000 patients and 3,100 facilities for the risk analysis.

PREDICTOR

Percentage of facility patient-months with hemoglobin level<10 g/dL.

OUTCOME

Patient-level RBC transfusion rates.

MEASUREMENTS

Monthly epoetin alfa and intravenous iron doses, mean hemoglobin levels, and RBC transfusion rates; percentage of facility patient-months with hemoglobin levels<10 g/dL (exposure) and patient-level RBC transfusion rates (follow-up).

RESULTS

Percentages of patients with hemoglobin levels<10 g/dL increased every year from 2007 (6%) to 2011 (~11%). Epoetin alfa doses, iron doses, and transfusion rates remained relatively stable through 2010 and changed in 2011. Median monthly epoetin alfa and iron doses decreased 25% and 43.8%, respectively, and monthly transfusion rates increased from 2.8% to 3.2% in 2011, a 14.3% increase. Patients in facilities with the highest prevalence of hemoglobin levels<10 g/dL over 3 months were at ~30% elevated risk of receiving RBC transfusions within the next 3 months (relative risk, 1.28; 95% CI, 1.22-1.34).

LIMITATIONS

Possibly incomplete claims data; smaller units excluded; hemoglobin levels reported monthly for patients receiving epoetin alfa; transfusions usually not administered in dialysis units.

CONCLUSIONS

Dialysis facility treatment practices, as assessed by percentage of patient-months with hemoglobin levels<10 g/dL over 3 months, were associated significantly with risk of transfusions in the next 3 months for all patients in the facility, regardless of patient case-mix.

Cytokine patterns in greenhouse workers occupationally exposed to α-cypermethrin: an observational study

The immunotoxicity of the synthetic pyrethroid α-cypermethrin (αCYP) was assessed in 30 occupationally exposed greenhouse workers and 30 non-exposed controls by comparing plasma levels of IL-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12p70, TNF-α, TNF-β and INF-γ. Urinary 3-phenoxybenzoic acid was used as an exposure biomarker. Exposed workers showed neither clinical signs of immunosuppression nor alterations in total leukocytes or leukocyte subpopulations, whereas significant differences (p<0.05) were found for IL-12p70 and highly significant differences (p<0.001) for INF-γ, IL-2 and IL-8, which are involved in antitumor immunity and response to infection. Proinflammatory cytokines IL-2, IL-8, IL-12p70 and IFN-γ play a significant role against infection and cancer. We report the first data on the ability of αCYP to reduce proinflammatory cytokine levels in an exposed healthy human population. Findings support the hypothesis that pyrethroid exposure may reduce host defenses against infection and cancer, particularly in subjects with impaired immune capacity.

Articulation-based sound perception in verbal repetition: a functional NIRS study

Verbal repetition is a fundamental language capacity where listening and speaking are inextricably coupled with each other. We have recently reported that the left inferior frontal gyrus (IFG) harbors articulation-based codes, as evidenced by activation during repetition of meaningless speech sounds, i.e., pseudowords. In this study, we aimed at confirming this finding and further investigating the possibility that sound perception as well as articulation is subserved by neural circuits in this region. Using functional near-infrared spectroscopy (fNIRS), we monitored changes of hemoglobin (Hb) concentration at IFG bilaterally, while subjects verbally repeated pseudowords and words. The results revealed that the proportion of oxygenated hemoglobin (O₂Hb) over total Hb was significantly higher at the left IFG during repetition of pseudowords than that of words, replicating the observation by functional MRI and indicating that the region processes articulatory codes for verbal repetition. More importantly for this study, hemodynamic modulations were observed at both IFG during passive listening without repetition to various sounds, including natural environmental sounds, animal vocalizations, and human non-speech sounds. Furthermore, the O₂Hb concentration increased at the left IFG but decreased at the right IFG for both speech and non-speech sounds. These findings suggest that both speech and non-speech sounds may be processed and maintained by a neural mechanism for sensorimotor integration using articulatory codes at the left IFG.

Hemoglobin point-of-care testing: the HemoCue system

Besides the use of traditional laboratory resources, the diagnosis of anemia can also be accomplished by assessing hemoglobin (Hb) concentration with point-of-care testing (POCT) devices such as the HemoCue test systems. In several situations, these devices might suitably replace traditional laboratory testing, including several areas of health care where a very rapid Hb measurement might be required to make immediate therapeutic decisions. The use of these devices, however, should fulfill some basic criteria, including economic, clinical, and regulatory issues; appropriate training of the users and knowledge of test requirements, performance, limitations, and potential interferences; the use of venous and arterial sampling, when possible; and a rigorous quality assessment, which should be under the responsibility of laboratory professionals. Because of its optimal performance along with the fact that the HemoCue is probably one of the most commonly used devices worldwide, the aim of this article is to review the literature data about the performance of this test system as compared with laboratory reference testing estimations and according to the biological matrix.

Steady state hemoglobin concentration and packed cell volume in homozygous sickle cell disease patients in Lagos, Nigeria

BACKGROUND

Sickle cell disease is a genetic disorder of hemoglobin causing myriad of pathology including anemia. The purpose of this study was to evaluate the baseline values of steady state hemoglobin and packed cell volume as a guide to managing the early recognition of hemolytic crises in sickle cell anemia.

METHODS

A cross-sectional study was conducted among the sickle cell patients attending the Sickle Cell clinic of Lagos State University Teaching Hospital, Ikeja. A blood sample of 4.5 ml blood was collected from each participant for hemoglobin concentration and packed cell volume. All blood samples were also screened for HIV and hemoglobin phenotypes were done using cellulose acetate hemoglobin electrophoresis at pH 8.6.

RESULTS

A total of 98 subjects in steady state were recruited, consisting of 53 (54.1%) females and 45 (45.9%) males. The overall means were 7.92±1.49 and 24.46±4.76; a female mean of 7.73±1.45; 23.89±4.60, and a male mean of 8.14±1.54 and 25.14±4.91 were obtained for hemoglobin and packed cell volume, respectively. Sixty - nine of the 98 (70.40%) subjects have been previously transfused with blood.

CONCLUSION

The mean hemoglobin concentration and packed cell volume in males was higher than females. The overall mean was lower than what was expected for age and sex. Over two-third of sickle cell anemia population had been transfused.

Simultaneous second harmonic generation of multiple wavelength laser outputs for medical sensing

Multiple wavelength light sources in the medical spectral window region are useful for various medical sensing applications in tissue by distinguishing the absorption and scattering coefficients optically. We propose a simultaneous second harmonic generation of multiple wavelength fiber laser output using parallel channels of periodically-poled lithium niobate (PPLN) waveguides. High intensity dual wavelength lasing output is experimentally realized with two tunable fiber Bragg gratings of 1,547.20 nm and 1,554.48 nm for the efficient conversion to the half wavelengths, 773.60 nm and 777.24 nm, by using two parallel PPLN channels. Compared with a conventional dual second harmonic generation (SHG) configuration based on two different input wavelengths from each independent light source, this method has a relatively higher efficiency to align the input light beam into the adjacent parallel PPLN channels simultaneously. The use of fiber lasers offers several advantages since they are relatively inexpensive, provide high power in excess of tens of watts, are widely tunable, and can produce pulses from milliseconds to femtoseconds.

Phasor representation of oxy- and deoxyhemoglobin concentrations: what is the meaning of out-of-phase oscillations as measured by near-infrared spectroscopy?

We propose a phasor representation for oscillations at a given frequency (or relatively narrow frequency band) of hemoglobin concentrations in tissue, as well as hemoglobin concentrations measured by near-infrared spectroscopy. This representation provides a straightforward visualization of the phase relationships between oscillations of oxy-, deoxy-, and total hemoglobin concentrations ([HbO], [Hb], and [HbT], respectively). We observe that measured oscillations of [Hb] and [HbO] with a phase difference that is neither 0 nor pi must result from the combination of different physiological processes that are out of phase (or time shifted) with respect to each other. Finally, we propose the use of cross-correlation phasors to map phase relationships and correlation levels among hemoglobin oscillations measured at spatially distinct locations at a given frequency. Such a representation may find a natural application in the study of functional connectivity networks in the brain.