Alkaline haematin D-575, a new tool for the determination of haemoglobin as an alternative to the cyanhaemiglobin method. I. Description of the method

High-affinity VNARs targeting human hemoglobin: Screening, stability and binding analysis

Hemoglobin, composed of α- and β-chains, is essential for oxygen transport and is key in diagnosing and treating gastrointestinal and blood disorders. It also aids in detecting blood contamination and estimating transfusion volumes. Immunological methods, based on antigen-antibody interactions, are distinguished by their high sensitivity and accuracy. Consequently, it is necessary to develop hemoglobin-specific antibodies characterized by high specificity and affinity to enhance detection accuracy. The variable domain of the new antigen receptor (VNAR) from sharks, the smallest antigen-binding unit, is ideal for disease diagnosis and treatment due to its small size, stability, and high affinity. In this study, Chiloscyllium plagiosum was immunized with human hemoglobin protein. Nine VNAR immune libraries with sizes ranging from 1 × 108 to 1.82 × 109 colony-forming units (CFU) were constructed and biopanned using phage display, resulting in three hemoglobin-specific VNAR sequences (5-10C, 7-11A, T-12-4D). These sequences were inserted into pTT5-TEV-Fc vectors and transfected into HEK 293F cells. The resulting VNAR-Fc fusion proteins were purified from the cell culture supernatants. Binding activity, cross-reactivity, physicochemical stability, and epitope competition were evaluated using non-competitive enzyme-linked immunosorbent assay (ELISA) and biolayer interferometry (BLI). T-12-4D-Fc exhibited the highest affinity with a KD value of 7.59 nM and superior physicochemical stability. It maintained over 80 % binding activity at 90 °C, over 51 % in extreme pH conditions (pH 2 and 12), and above 65 % in urea concentrations up to 8 mol/L. Its binding activity remained largely unaffected after 6 h of incubation in human plasma-like medium (HPLM). The binding epitope competition results showed that 5-10C-Fc and T-12-4D-Fc targeted the same hemoglobin epitope. Molecular dynamics simulations revealed hydrogen bonds as the primary interaction force between VNARs and hemoglobin. Furthermore, a double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) method was established for the detection of human hemoglobin, utilizing T-12-4D-Fc as the coating antibody. This technique demonstrated high accuracy, reproducibility and specificity when applied to human whole blood samples. Hence, the identified VNARs, particularly T-12-4D, demonstrated good stability, specificity, and high affinity, filling the gap of hemoglobin-targeting shark-derived single-domain antibodies and offering a foundation for diagnosing and monitoring hemoglobin-related diseases.

Red Blood Cell Cryopreservation with Minimal Post-Thaw Lysis Enabled by a Synergistic Combination of a Cryoprotecting Polyampholyte with DMSO/Trehalose

From trauma wards to chemotherapy, red blood cells are essential in modern medicine. Current methods to bank red blood cells typically use glycerol (40 wt %) as a cryoprotective agent. Although highly effective, the deglycerolization process, post-thaw, is time-consuming and results in some loss of red blood cells during the washing procedures. Here, we demonstrate that a polyampholyte, a macromolecular cryoprotectant, synergistically enhances ovine red blood cell cryopreservation in a mixed cryoprotectant system. Screening of DMSO and trehalose mixtures identified optimized conditions, where cytotoxicity was minimized but cryoprotective benefit maximized. Supplementation with polyampholyte allowed 97% post-thaw recovery (3% hemolysis), even under extremely challenging slow-freezing and -thawing conditions. Post-thaw washing of the cryoprotectants was tolerated by the cells, which is crucial for any application, and the optimized mixture could be applied directly to cells, causing no hemolysis after 1 h of exposure. The procedure was also scaled to use blood bags, showing utility on a scale relevant for application. Flow cytometry and adenosine triphosphate assays confirmed the integrity of the blood cells post-thaw. Microscopy confirmed intact red blood cells were recovered but with some shrinkage, suggesting that optimization of post-thaw washing could further improve this method. These results show that macromolecular cryoprotectants can provide synergistic benefit, alongside small molecule cryoprotectants, for the storage of essential cell types, as well as potential practical benefits in terms of processing/handling.

Rapid, convenient, and highly sensitive detection of human hemoglobin in serum using a high-affinity bivalent antibody-enzyme complex

Human hemoglobin (Hb) is a biomarker of several diseases, and monitoring of Hb levels is required during emergent surgery. However, rapid and sensitive Hb detection methods are yet to be developed. The present study established a rapid, convenient, and highly sensitive detection method for Hb in human serum using a bivalent antibody-enzyme complex (AEC). AECs are promising sensing elements because of their ability to bind specific targets and their catalytic activity that produce signals. We recently reported a convenient and universal method to fabricate bivalent AECs with two antibody fragments, using the SpyCatcher/SpyTag system. The present study applied a bivalent AEC for highly sensitive and quantitative detection of human Hb. The bivalent anti-Hb AEC was successfully prepared by incubating both N- and C-terminus SpyCatcher-fused glucose dehydrogenase and SpyTag-fused anti-Hb single-chain variable fragments at 4 °C. As expected, the bivalent AEC for Hb with a multimeric structure showed higher affinity than the monovalent AEC, by means of avidity effects, unlike that for soluble epidermal growth factor receptor with a monomeric structure; this contributed to a great improvement in sensitivity. Finally, we established a rapid and wash-free homogeneous electrochemical detection system for Hb by integrating magnetic beads. The linear range of the system completely covered the clinically required Hb levels, even in human serum. This technology provides an ideal point-of-care test for Hb and other multimeric biomarkers.

Function of Hemoglobin-Based Oxygen Carriers: Determination of Methemoglobin Content by Spectral Extinction Measurements

Suspensions of hemoglobin microparticles (HbMPs) are promising tools as oxygen therapeutics. For the approval of clinical studies extensive characterization of these HbMPs with a size of about 750 nm is required regarding physical properties, function, pharmaco-kinetics and toxicology. The standard absorbance measurements in blood gas analyzers require dissolution of red blood cells which does not work for HbMP. Therefore, we have developed a robust and rapid optical method for the quality and functionality control of HbMPs. It allows simultaneous determination of the portion of the two states of hemoglobin oxygenated hemoglobin (oxyHb) and deoxygenated hemoglobin (deoxyHb) as well as the content of methemoglobin (metHb). Based on the measurement of collimated transmission spectra between 300 nm and 800 nm, the average extinction cross section of HbMPs is derived. A numerical method is applied to determine the composition of the HbMPs based on their wavelength-dependent refractive index (RI), which is a superposition of the three different states of Hb. Thus, light-scattering properties, including extinction cross sections can be simulated for different compositions and sizes. By comparison to measured spectra, the relative concentrations of oxyHb, deoxyHb, metHb are accessible. For validation of the optically determined composition of the HbMPs, we used X-ray fluorescence spectrometry for the ratio of Fe(II) (oxyHb/deoxyHb) and Fe(III) (metHb). High accuracy density measurements served to access heme-free proteins, size was determined by dynamic light scattering and analytical centrifugation and the shape of the HbMPs was visualized by electron and atomic force microscopy.

Hemolysis and Plasma Free Hemoglobin During Extracorporeal Membrane Oxygenation Support: From Clinical Implications to Laboratory Details

Venovenous and venoarterial extracorporeal membrane oxygenation (ECMO) are lifesaving supports that are more and more frequently used in critically ill patients. Despite of major technological improvements observed during the last 20 years, ECMO-associated hemolysis is still a complication that may arise during such therapy. Hemolysis severity, directly appreciated by plasma free hemoglobin concentration, may be present with various intensity, from a nonalarming and tolerable hemolysis to a highly toxic one. Here, we propose a review dedicated to extracorporeal membrane oxygenation (ECMO)-associated hemolysis, with a particular emphasis on pathophysiology, prevalence, and clinical consequences of such complication. We also focus on laboratory assessment of hemolysis and on the limits that have to be known by clinicians to prevent and manage hemolytic events.

Performance and mechanism of polypeptidylated hemoglobin (Hb)/iron oxide magnetic composites for enhanced dye removal

Composites of polypeptidylated hemoglobin supported on different iron oxide weights (0.5:1 and 1:1) were developed and demonstrated to function as efficient adsorbents for Eriochrome black-T dye removal. The synthesis of these adsorbents were performed through N-carboxyanhydride (NCA) polymerization at low temperature (4 °C) and near-neutral pH for 24 h followed by chemical co-precipitation. The synthesized adsorbents were found to exhibit BET surface area (54-87 m²/g), pore volume (0.30-0.35 cm³/g), average pore diameter (160-218 Å) and average pore width (136-171 Å). The developed adsorbents were tested in a batch dye adsorption system. Adsorption was found to follow pseudo-second order kinetics and the Langmuir adsorption capacities were 123, 204 and 217 mg/g for Fe₃O₄, 0.5:1 and 1:1 adsorbent samples, respectively. Chemical regeneration was successfully carried out using methanol and the reusability of the adsorbents were demonstrated with a decrease in adsorption capacities from ∼49 to ∼33 mg/g after the fourth reuse.

Prevalence and knowledge of heavy menstrual bleeding among gynecology outpatients by scanning a WeChat QR Code

The aim of this study was to assess menstrual blood loss (MBL) and knowledge of heavy menstrual bleeding (HMB) among the gynecology outpatients at Peking University People’s Hospital, by scanning a WeChat (a social media application software developed by Tencent) QR Code using a mobile phone or tablet. This survey was conducted among outpatients who were treated at the Gynecology Department of Peking University People’s Hospital between September 2016 and November 2016. All participants filled up the questionnaires and scales through WeChat: general information questionnaire, Pictorial Blood Loss Assessment Chart (PBAC), Menorrhagia Multi-Attribute Quality-of-Life Scale (MMAS), and HMB knowledge questionnaire. Menstrual blood volume was assessed by the PBAC and self-assessment. Among the 1152 patients who filled out the survey, 77.4% (892/1152) had normal menstrual cycle (assessed by the patients), 15.6% (180/1152) patients described themselves as HMB, whereas the results from PBAC showed that 58.0% (668/1152) had HMB (PBAC ≥100). Among patients with PBAC ≥100, only 26.8% (179/668) patients reported HMB through self-assessment. Regarding its impact on daily life, the MMAS scores of HMB patients (PBAC ≥100) were significantly lower compared to those with normal blood loss (P<0.001). Regarding the awareness to HMB, 63.2% (728/1152) of the patients were not familiar with HMB. HMB is a common abnormal uterine bleeding and is frequently found among Chinese gynecology outpatients. HMB has major impacts on a woman’s quality of life, affecting both physical and emotional health domains. Since women generally have low levels of awareness and understanding of HMB, they could assess their blood loss using the PBAC, which they can forward to their health care provider using a mobile phone or tablet and the WeChat platform. This tool may be effortlessly used by the health care providers and patients to easily share HMB-related data.

Measurement and interpretation of hemoglobin concentration in clinical and field settings: a narrative review

Anemia affects over 800 million women and children globally. Defined as a limited or insufficient functional red blood cell supply in peripheral blood, anemia causes a reduced oxygen supply to tissues and can have serious health consequences for women and children. Hemoglobin (Hb) concentration is most commonly measured for anemia diagnosis. Methods to measure Hb are usually invasive (requiring a blood sample); however, advances in diagnostic and clinical chemistry over the past decade have led to the development of new noninvasive methods. Accurate diagnosis at the individual level is important to identify individuals who require treatment. At the population level, anemia prevalence estimates are often the impetus for national nutrition policies or programs. Thus, it is essential that methods for Hb measurement are sensitive, specific, accurate, and reproducible. The objective of our narrative review is to describe the basic principles, advantages, limitations, and quality control issues related to methods of Hb measurement in clinical and field settings. We also discuss other biomarkers and tests that can help to determine the severity and underlying causes of anemia. In conclusion, there are many established and emerging methods to measure Hb concentration, each with their own advantages, limitations, and factors to consider before use.

Hemin-catalyzed biomimetic oxidative phenol–indole [3 + 2] reactions in aqueous media

A hemin/H₂O₂ catalytic system for oxidative phenol–indole [3 + 2] coupling in aqueous solution has been developed, enabling benign synthesis of valuable benzofuroindolines under sustainable conditions.

Redox control and autoxidation of class 1, 2 and 3 phytoglobins from Arabidopsis thaliana

Despite a recent increase in interest towards phytoglobins and their importance in plants, much is still unknown regarding their biochemical/biophysical properties and physiological roles. The present study presents data on three recombinant Arabidopsis phytoglobins in terms of their UV-vis and Raman spectroscopic characteristics, redox state control, redox potentials and autoxidation rates. The latter are strongly influenced by pH for all three hemoglobins - (with a fundamental involvement of the distal histidine), as well as by added anion concentrations - suggesting either a process dominated by nucleophilic displacement of superoxide for AtHb2 or an inhibitory effect for AtHb1 and AtHb3. Reducing agents, such as ascorbate and glutathione, are found to either enhance- (presumably via direct electron transfer or via allosteric regulation) or prevent autoxidation. HbFe3+ reduction was possible in the presence of high (presumably not physiologically relevant) concentrations of NADH, glutathione and ascorbate, with differing behaviors for the three globins. The iron coordination sphere is found to affect the autoxidation, redox state interconversion and redox potentials in these three phytoglobins.

Efficient removal of dyes from aqueous solutions using a novel hemoglobin/iron oxide composite

Magnetic particles entrapped in different matrices that display high thermal stability, low toxicity, interactive functions at the surface, and high saturation magnetization are of great interest. The objective of this work was to synthesize a novel hemoglobin/iron oxide composite (Hb/Fe₃O₄) for the removal of different dyes (indigo carmine, naphthol blue black, tartrazine, erythrosine, eriochrome black T and bromophenol blue) from aqueous solutions. The Hb/Fe₃O₄ composite was characterized using scanning electron microscopy (SEM), laser diffraction particle size analysis, FT-IR spectroscopy, isoelectric point determination and thermogravimetric analysis (TGA). The Hb/Fe₃O₄ composite showed high removal efficiency toward all the different classes of dyes studied and the mechanism of adsorption was dominated by electrostatic interaction. Adsorption was found to follow pseudo-second order kinetic model and Langmuir isotherm. The Langmuir monolayer adsorption capacities for all the dyes range from 80 to 178 mg/g. The Hb/Fe₃O₄ composite possesses extra advantage of being easily isolated from aqueous suspension using an external magnet. The stability of the prepared Hb/Fe₃O₄ composite was also demonstrated.

Relationship of planter pressure and glycemic control in type 2 diabetic patients with and without neuropathy

INTRODUCTION

Foot disease is a common complication of type 2 diabetes that can have tragic consequences. Abnormal plantar pressures are considered to play a major role in the pathologies of neuropathic ulcers in the diabetic foot.

AIM

To examine Relationship of Planter Pressure and Glycemic Control in Type 2 Diabetic Patients with and without Neuropathy.

MATERIALS AND METHODS

The study was conducted on 50 type 2 diabetic patients and 30 healthy volunteers. BMI calculation, disease duration, Hemoglobin A1c and presence of neuropathy (by history, foot examination and DN4 questionnaire) were recorded. Plantar pressure was recorded for all patients using the Mat-scan (Tekscan, Inc.vers. 6.34 Boston USA) in static conditions (standing) and dynamic conditions (taking a step on the Mat-scan). Plantar pressures (kPa) were determined at the five metatarsal areas, mid foot area, medial and lateral heel areas and medial three toes.

RESULTS

Static and dynamic plantar pressures in both right and left feet were significantly higher in diabetic with neuropathy group than in control group in measured areas (P<0.05). Static and dynamic pressures in right and left feet were significantly higher in diabetic with neuropathy group than in diabetic without neuropathy group in measured areas (P<0.05). On comparison between controls and diabetic without neuropathy group there was a significant difference in plantar pressures especially in metatarsal areas (P<0.05). No significant correlations were present between the studied variables age, disease duration, BMI and HbA1c and plantar pressures in all studied areas.

CONCLUSION

Persons with diabetic neuropathy have elevated peak plantar pressure (PPP) compared to patients without neuropathy and control group. HbA1c% as a surrogate for glycemic control had no direct impact on peak planter pressure, yet it indirectly impacts neuropathy evolution through out disease duration eventually leading to the drastic planter pressure and gait biomechanics changes.

Natural Porphyrins Accelerating the Phototransformation of Benzo[a]pyrene in Water

Phototransformation is one of the most important transformation pathways of organic contaminants in the water environment. However, how active compounds enable and accelerate the phototransformation of organic pollutants remains to be elucidated. In this study, the phototransformation of benzo[a]pyrene (BaP, the first class "human carcinogens") by various natural porphyrins under solar irradiation was investigated, including chlorophyll a, sodium copper chlorophyllin, hematin, cobalamin, and pheophorbide a. Transformation efficiency of BaP varied considerably with chemical stabilities of the porphyrins. Porphyrins with a lower stability displayed higher BaP transformation efficiencies. BaP transformation had a significant positive correlation with the production of singlet oxygen. Identical phototransformation products of BaP were observed for all investigated porphyrins, and the main products were identified as BaP-quinones, including BaP-1,6-dione, BaP-3,6-dione, and BaP-6,12-dione. The mechanism of natural porphyrins accelerating the BaP phototransformation in water was proposed to proceed via the photocatalytic generation of singlet oxygen resulting in the transformation of BaP to quinones.

Increased Plasmodium chabaudi malaria mortality in mice with nutritional iron deficiency can be reduced by short-term adjunctive iron supplementation

BACKGROUND

Iron deficiency is the most widespread nutrient deficiency and an important cause of developmental impairment in children. However, some studies have indicated that iron deficiency can also protect against malaria, which is a leading cause of childhood morbidity and mortality in large parts of the world. This has rendered interventions against iron deficiency in malaria-endemic areas controversial.

METHODS

The effect of nutritional iron deficiency on the clinical outcome of Plasmodium chabaudi AS infection in A/J mice and the impact of intravenous iron supplementation with ferric carboxymaltose were studied before and after parasite infection. Plasma levels of the iron status markers hepcidin and fibroblast growth factor 23 were measured in animals surviving and succumbing to malaria, and accompanying tissue pathology in the liver and the spleen was assessed.

RESULTS

Nutritional iron deficiency was associated with increased mortality from P. chabaudi malaria. This increased mortality could be partially offset by carefully timed, short-duration adjunctive iron supplementation. Moribund animals were characterized by low levels of hepcidin and high levels of fibroblast growth factor 23. All infected mice had extramedullary splenic haematopoiesis, and iron-supplemented mice had visually detectable intracellular iron stores.

CONCLUSIONS

Blood transfusions are the only currently available means to correct severe anaemia in children with malaria. The potential of carefully timed, short-duration adjunctive iron supplementation as a safe alternative should be considered.

Comparison of potential higher order reference methods for total haemoglobin quantification-an interlaboratory study

The total haemoglobin (Hb) concentration in blood is one of the most frequently measured analytes in clinical medicine because of its significance for evaluating the health state of a human. The spectrophotometric cyanmethaemoglobin (HiCN) method is the internationally accepted conventional reference method to determine this biomarker. It is frequently used in clinical routine diagnostics but is not traceable to the International System of Units and thus does not meet highest metrological demands. A further critical issue is the toxicity of the necessary potassium cyanide. Different methods to solve these problems are reported here. They all were validated against the HiCN method in an interlaboratory comparison by measuring the total Hb concentration present in the certified reference material JCCRM 912-2M. Methods considered were the spectrophotometric alkaline haematin detergent (AHD) method as well as several isotope dilution (ID)-based approaches. The latter include inductively coupled plasma mass spectrometry (ICP-MS), species-specific (SS) ICP-MS, organic MS and Raman spectrometry. Graphical abstract ᅟ.

Leisure-time, occupational, household physical activity and insulin resistance (HOMAIR) in the Midlife in the United States (MIDUS) national study of adults

Physical activity is a critical cornerstone of successful diabetes prevention and management. Current U.S. physical activity guidelines do not differentiate among physical activity for leisure, work, or other purposes, effectively implying that physical activity in any domain confers the same health benefits. It is currently unknown whether physical activity performed in different domains (leisure-time physical activity = LTPA, occupational physical activity = OPA, and household physical activity = HPA) is associated with insulin resistance. The associations between LTPA, OPA, HPA, and insulin resistance (indexed by homeostatic model assessment of insulin resistance = HOMAIR) were determined in the MIDUS (Midlife in the U.S.; 1995-2006) national study (N = 1229, ages 34-84). Not meeting physical activity guidelines with LTPA was associated with a 34% higher HOMAIR among participants with diabetes, 42% higher HOMAIR among participants with prediabetes, and 17% higher HOMAIR among participants with normal glucoregulation. These associations were slightly attenuated but remained significant after further adjusting for obesity status, education, smoking, and alcohol intake. There was no evidence that engaging in OPA or HPA was significantly associated with HOMAIR. These results confirm the health-promoting role of LTPA and suggest that LTPA may provide unique glucoregulatory benefits, as opposed to HPA and OPA. Physical activity domain is an important dimension that potentially belongs in the guidelines, similarly to intensity, frequency, duration, and type.

Assessment of free fatty acids and cholesteryl esters delivered in liposomes as novel class of antibiotic

BACKGROUND

Healthcare associated infections (HAI) with multidrug-resistant (MDR) bacteria continue to be a global threat, highlighting an urgent need for novel antibiotics. In this study, we assessed the potential of free fatty acids and cholesteryl esters that form part of the innate host defense as novel antibacterial agents for use against MDR bacteria.

METHODS

Liposomes of six different phospholipid mixtures were employed as carrier for six different fatty acids and four different cholesteryl esters. Using a modified MIC assay based on DNA quantification with the fluoroprobe Syto9, formulations were tested against Gram-positive and Gram-negative bacteria implicated in HAI. Formulations with MIC values in the low μg/mL range were further subjected to determination of minimal bactericidal activity, hemolysis assay with sheep erythrocytes, and cytotoxicity testing with the human liver cell line HepG2. The potential for synergistic activity with a standard antibiotic was also probed.

RESULTS

Palmitic acid and stearic acid prepared in carrier 4 (PA4 and SA4, respectively) were identified as most active lipids (MIC against MDR Staphylococcus epidermidis was 0.5 and 0.25 μg/mL, respectively; MIC against vancomycin resistant Enterococcus faecalis (VRE) was 2 and 0.5 μg/mL, respectively). Cholesteryl linoleate formulated with carrier 3 (CL3) exhibited activity against the S. epidermidis strain (MIC 1 μg/mL) and a Pseudomonas aeruginosa strain (MIC 8 μg/mL) and lowered the vancomycin MIC for VRE from 32-64 μg/mL to as low as 4 μg/mL. At 90 μg/mL PA4, SA4, and CL3 effected less than 5 % hemolysis over 3 h and PA4 and CL3 did not exhibit significant cytotoxic activity against HepG2 cells when applied at 100 μg/mL over 48 h.

CONCLUSIONS

Our results showed that selected fatty acids and cholesteryl esters packaged with phospholipids exhibit antibacterial activity against Gram-positive and Gram-negative bacteria and may augment the activity of antibiotics. Bactericidal activity could be unlinked from hemolytic and cytotoxic activity and the type of phospholipid carrier greatly influenced the activity. Thus, fatty acids and cholesteryl esters packaged in liposomes may have potential as novel lipophilic antimicrobial agents.

Hemophagocytosis in Experimental Visceral Leishmaniasis by Leishmania donovani

Hemophagocytosis is a phenomenon in which macrophages phagocytose blood cells. There are reports on up-regulated hemophagocytosis in patients with infectious diseases including typhoid fever, tuberculosis, influenza and visceral leishmaniasis (VL). However, mechanisms of infection-associated hemophagocytosis remained elusive due to a lack of appropriate animal models. Here, we have established a mouse model of VL with hemophagocytosis. At 24 weeks after infection with 1 x 10⁷Leishmania donovani promastigotes, BALB/cA mice exhibited splenomegaly with an average tissue weight per body weight of 2.96%. In the tissues, 28.6% of macrophages contained phagocytosed erythrocytes. All of the hemophagocytosing macrophages were parasitized by L. donovani, and higher levels of hemophagocytosis was observed in heavily infected cells. Furthermore, more than half of these hemophagocytes had two or more macrophage-derived nuclei, whereas only 15.0% of splenic macrophages were bi- or multi-nuclear. These results suggest that direct infection by L. donovani causes hyper-activation of host macrophages to engulf blood cells. To our knowledge, this is the first report on hemophagocytosis in experimental Leishmania infections and may be useful for further understanding of the pathogenesis.

Anemia is one of the major clinical manifestations during visceral leishmaniasis (VL), whereas mechanisms behind this symptom remain elusive. To get a better understanding of the responsible mechanism(s), we have developed for the first time a mouse model of VL exhibiting anemia. Mice chronically infected with L. donovani had low hematocrit, hemoglobin and erythrocyte counts while having up-regulated erythropoiesis, suggesting hemolytic events due to infection. We propose here that hemophagocytosis is one of the hemolytic events associated with anemia in the infected mice. The spleen is the major place for hemophagocytosis; there, multinucleated giant cells heavily infected with amastigotes are markedly observed and are the major cell type phagocytosing erythrocytes. These results suggest that heavy infection of macrophages with Leishmania parasites triggers phagocytosis of erythrocytes resulting in anemia during murine VL. Because hemophagocytosis has been reported in human VL cases, reproduction of the pathology in mice may facilitate an understanding of the mechanisms leading to anemia during VL.

"Meat juice" is not a homogeneous serological matrix

Meat juice samples are used in serological assays to monitor infectious diseases within the food chain. However, evidence of inferior sensitivity, presumably due to low levels of antibodies in the meat juice compared to serum, has been presented, and it has been suggested that adjusting the dilution factor of meat juice in proportion to its blood content could improve sensitivity. In the present study, the agreement between Toxoplasma gondii-specific immunoglobulin G (IgG) levels in meat juice and serum was evaluated, and whether the level of immunoglobulins in meat juice was dependent on its blood content. Serum and meat juice from diaphragm, heart, tongue, Musculus triceps brachii and M. semitendinosus were collected from 20 pigs experimentally infected with T. gondii. Analysis of total IgG, heme-containing proteins (hematin), and hemoglobin (Hb) revealed significant differences between samples from different muscles, with the highest levels in samples from heart and tongue, and the lowest in samples from leg muscles. Comparison of T. gondii-specific antibody titers in meat juice and serum revealed a strong positive correlation for meat juice from heart (rs=0.87; p<0.001), while it was lower for M. semitendinosus (rs=0.71; p<0.001) and diaphragm (rs=0.54; p=0.02). Meanwhile, the correlation between total IgG and T. gondii titer ratio (meat juice/serum) was highest in diaphragm (rs=0.77; p<0.001) followed by M. semitendinosus (rs=0.64; p=0.005) and heart (rs=0.50; p=0.051). The correlation between Hb and T. gondii titer ratio was only significant for diaphragm (rs=0.65; p=0.008), and for hematin no significant correlation was recorded. In conclusion, the specific IgG titers in meat juice appeared to depend on the total IgG level, but the correlation to blood (Hb or hematin) was poor. Importantly, large significant differences in total IgG levels as well as in specific antibody titers were recorded, depending on the muscle the meat juice had been extracted from.

Fructosamine is a useful indicator of hyperglycaemia and glucose control in clinical and epidemiological studies--cross-sectional and longitudinal experience from the AMORIS cohort

CONTEXT

Fructosamine is a glycemic biomarker which may be useful for indication and control of diabetes respectively.

OBJECTIVE

The objective of the study was to evaluate fructosamine as an indicator of hyperglycaemia and glucose control in subjects with diabetes.

DESIGN, SETTING & PATIENTS

From the AMORIS cohort, subjects with serum glucose, fructosamine and HbA1c from the same examination were studied cross-sectionally and longitudinally (n = 10,987; 5,590 overnight-fasting). The guidelines of the American Diabetes Association were followed for classification of prediabetes and diabetes. Separate analyses were performed in patients with a newly detected or a known diagnosis of type 1 or type 2 diabetes respectively.

RESULTS

All three biomarkers were strongly correlated. With regard to the association between fructosamine and HbA1c Pearson linear correlation coefficients in the range of 0.67-0.75 were observed in fasting and non-fasting subjects with type 1 or type 2 diabetes. Analyses of glucose control in fasting patients with type 2 diabetes having all three biomarkers measured at three separate occasions within on average 290 days of the index examination showed similar trends over time for glucose, fructosamine and HbA1c. Discrimination of subjects with and without diabetes across the range of fructosamine levels was good (area under curve (AUC) 0.91-0.95) and a fructosamine level of 2.5 mmol/L classified subjects to diabetes with a sensitivity of 61% and a specificity of 97%.

CONCLUSIONS

Fructosamine is closely associated with HbA1c and glucose respectively and may be a useful biomarker of hyperglycaemia and glucose control in clinical and epidemiological studies.

Antioxidant Enzymes and Lipid Peroxidation in Type 2 Diabetes Mellitus Patients with and without Nephropathy

BACKGROUND

Oxidative stress has been considered to be a pathogenic factor of diabetic complications including nephropathy. There are many controversies and limited studies regarding the antioxidant enzymes in diabetic nephropathy.

AIM

This study was to evaluate the levels of antioxidant enzymes and lipid peroxidation in Type-2 Diabetes Mellitus (DM) patients with and without nephropathy.

MATERIALS AND METHODS

The study included 90 age and sex matched subjects. Blood samples of all subjects were analyzed for all biochemical and oxidative stress parameters.

RESULTS

The malondialdehyde (MDA) levels and catalase (CAT) activity were significantly increased and reduced glutathione (GSH) levels and activities of glutathione peroxidase (GPx) and glutathione reductase (GR) were significantly decreased in Type-2 DM with and without nephropathy as compared to controls and also in Type-2 DM with nephropathy as compared to Type-2 DM without nephropathy. There were an excellent positive correlation of glycohemoglobin (HbA1c) with MDA and a good negative correlation of GPx with GSH in controls. There were positive correlations of GR, CAT, and superoxide dismutase (SOD) with MDA in Type-2 diabetes patients with nephropathy.

CONCLUSIONS

Intensity of oxidative stress in Type-2 diabetic patients with nephropathy is greater when compared with Type-2 diabetic patients without nephropathy as compared to the controls.

Intravenous ferric carboxymaltose accelerates erythropoietic recovery from experimental malarial anemia

Iron restriction has been proposed as a cause of erythropoietic suppression in malarial anemia; however, the role of iron in malaria remains controversial, because it may increase parasitemia. To investigate the role of iron-restricted erythropoiesis, A/J mice were infected with Plasmodium chabaudi AS, treated with intravenous ferric carboxymaltose at different times, and compared with untreated controls. Iron treatment significantly increased weight and hemoglobin nadirs and provided enhanced reticulocytosis and faster recovery, compared with controls. Our findings challenge the restrictive use of iron therapy in malaria and show the need for trials of intravenous ferric carboxymaltose as an adjunctive treatment for severe malarial anemia.

Perceived weight discrimination amplifies the link between central adiposity and nondiabetic glycemic control (HbA1c)

BACKGROUND

While the preclinical development of type 2 diabetes is partly explained by obesity and central adiposity, psychosocial research has shown that chronic stressors such as discrimination have health consequences as well.

PURPOSE

We investigated the extent to which the well-established effects of obesity and central adiposity on nondiabetic glycemic control (indexed by HbA(1c)) were moderated by a targeted psychosocial stressor linked to weight: perceived weight discrimination.

METHODS

The data came from the nondiabetic subsample (n = 938) of the Midlife in the United States (MIDUS II) survey.

RESULTS

Body mass index (BMI), waist-to-hip ratio, and waist circumference were linked to significantly higher HbA(1c) (p < 0.001). Multivariate-adjusted models showed that weight discrimination exacerbated the effects of waist-to-hip ratio on HbA(1c) ( p < 0.05), such that people who had higher waist-to-hip ratios and reported weight discrimination had the highest HbA(1c) levels.

CONCLUSION

Understanding how biological and psychosocial factors interact at nondiabetic levels to increase vulnerability could have important implications for public health and education strategies. Effective strategies may include targeting sources of discrimination rather than solely targeting the health behaviors and practices of overweight and obese persons.

Estudo retrospectivo das implicações maternas, fetais e perinatais em mulheres portadoras de diabetes, em 20 anos de acompanhamento no Hospital Escola da Universidade Federal do Triângulo Mineiro

OBJETIVOS: Avaliar implicações do diabetes melito (DM) na morbimortalidade materno-fetal, segundo experiência da Universidade Federal do Triângulo Mineiro. MATERIAIS E METODOS: Procedeu-se à análise retrospectiva dos prontuários de gestantes diabéticas assistidas entre 1990 e 2009 focando dados e complicações maternas e neonatais. RESULTADOS: A última gestação de 93 diabéticas foi avaliada, sendo 34 com DM tipo 1, em que se observou maior ocorrência de tocotrauma (p = 0,023) e retinopatia (p = 0,023). Vinte e uma pacientes tinham DM tipo 2; suas necessidades de insulina aumentaram progressivamente (p < 0,01) e observou-se maior prevalência de tabagismo (p = 0,004). Trinta e oito tiveram diabetes gestacional e iniciaram acompanhamento do diabetes em idade gestacional mais tardia (p < 0,001), tiveram mais antecedentes de macrossomia fetal (p = 0,028) e maior prevalência de fatores de risco cardiovascular. CONCLUSÕES: Não obstante melhora do controle glicêmico durante a gestação, nenhum dos grupos atingiu alvos glicêmicos ideais. Ainda assim, a maioria das gestações em diabéticas, conduzidas em nosso meio, evoluiu favoravelmente.

Frequency and risk factors associated with non-alcoholic fatty liver disease in patients with type 2 diabetes mellitus

OBJECTIVE

To evaluate the frequency of non-alcoholic fatty liver disease (NAFLD) in patients with type 2 diabetes mellitus (DM2) and to describe its risk factors.

SUBJECTS AND METHODS

Blood samples of 78 patients were collected for assessment of glycemic and lipid profile, liver enzymes, TNF-alpha and HOMA-IR. The diagnosis of NAFLD was established by ultrasound.

RESULTS

NAFLD was observed in 42% of patients who had greater BMI (p < 0.001), and frequency of hypertension (p < 0.001). Metabolic syndrome was more frequent in those with NAFLD (p = 0.019). The levels of aspartate, alanine aminotransferase, gamma-glutamyl transpeptidase, uric acid, TNF-alpha, insulin and HOMA-IR were significantly higher in patients with NAFLD than those without NAFLD.

CONCLUSION

Almost half of patients with DM2 were found to have NAFLD, and they have more elevated BMI, as well as higher levels of aminotransferases, gamma-GT, uric acid, TNF-alpha, insulin and HOMA-IR than subjects without NAFLD.

[Evaluation of the final stature reached by type 1 diabetes mellitus patients followed at an outsourced service]

Metabolic changes resulting from type 1 diabetes mellitus (DM1) may put growth and development at risk.

OBJECTIVE

To evaluate the final stature of DM1 patients and the interference of DM1 in growth.

SUBJECTS AND METHODS

The final height reached by 58 DM1 patients was evaluated according to anthropometric data and metabolic control.

RESULTS

Mean age was 26.4 years (15.0-51.0) and the duration of disease was of 9.6 years (1.4-25.0). Final stature was 165.1 cm (149.3-183.0) and the z-score for height was 0.09 (-1.76-2.85). In a subgroup (n = 34), it was possible to evaluate the effect of metabolic control on growth. Mean glycosylated hemoglobin was 12.2% (6.8-24.1) and the correlation between anthropometric data and glucose control was not considered statistically significant (p > 0.05).

CONCLUSION

We conclude that DM1 had no effect on the final stature, to the detriment of a poor metabolic control.

Regulation of a glutamyl-tRNA synthetase by the heme status

Glutamyl-tRNA (Glu-tRNA), formed by Glu-tRNA synthetase (GluRS), is a substrate for protein biosynthesis and tetrapyrrole formation by the C(5) pathway. In this route Glu-tRNA is transformed to delta-aminolevulinic acid, the universal precursor of tetrapyrroles (e.g., heme and chlorophyll) by the action of Glu-tRNA reductase (GluTR) and glutamate semialdehyde aminotransferase. GluTR is a target of feedback regulation by heme. In Acidithiobacillus ferrooxidans, an acidophilic bacterium that expresses two GluRSs (GluRS1 and GluRS2) with different tRNA specificity, the intracellular heme level varies depending on growth conditions. Under high heme requirement for respiration increased levels of GluRS and GluTR are observed. Strikingly, when intracellular heme is in excess, the cells respond by a dramatic decrease of GluRS activity and the level of GluTR. The recombinant GluRS1 enzyme is inhibited in vitro by hemin, but NADPH restores its activity. These results suggest that GluRS plays a major role in regulating the cellular level of heme.

A convenient HPLC assay for the determination of fructosamine-3-kinase activity in erythrocytes

Fructosamine-3-kinase (FN3K) mediates the regeneration of lysine from fructosamines formed on proteins as a result of the 'early' Maillard reaction. As fructosamines and advanced glycation endproducts derived therefrom are supposed to play an adverse role in the development of diabetic complications, FN3K is discussed as a protein-repairing enzyme. In this study, a method for the determination of FN3K activity in erythrocyte lysate is described which overcomes the complexity of currently known assays. The assay is based on the FN3K-dependent conversion of the synthetic UV-active fructosamine Nalpha-hippuryl-Nepsilon-(1-deoxy-D-fructosyl)lysine (BzGFruK) to Nalpha-hippuryl-Nepsilon-(phosphofructosyl)lysine (BzGpFruK). The FN3K activity was quantified by measuring the formation of BzGpFruK using RP-HPLC with UV detection. Identification of the metabolite BzGpFruK was achieved by means of UV and mass spectroscopy. The results are related to the content of haemoglobin for standardisation. First activity measurements with a chosen number of normoglycaemic subjects confirmed the convenient applicability of the method and showed distinctly different individual activities, as already discovered recently. The new established assay needs only the equipment of a routine laboratory with HPLC instrumentation. This should facilitate further studies about a possible relationship between the FN3K activity and the development of diabetic complications.

Oxidative stress and metallothionein expression in the liver of rats with severe thermal injury

The aim of this work was to study oxidative stress and the compensating mechanisms implicated in severe thermal injury using the burned rat model. Results showed that after thermal injury glutathione (GSH) level was decreased, oxidized glutathione (GSSG) and the ratio of GSSG/GSH increased both at 24 and 48 h in the liver. The activities of GSH-reductase (GSH-Rx) in the liver and GSH-peroxidase (GSH-Px) both in the liver and erythrocytes increased at 24 h and then decreased at 48 h. The level of alpha-tocopherol in plasma was reduced at 24 h. Lipid peroxide levels increased both at 24 and 48 h in the liver. The serum zinc level decreased, reaching a minimum at 12h, whereas liver zinc level was elevated and reached the maximum at 12 h. After severe thermal injury enhancement of metallothionein (MT) expression has been discovered for the first time. MT content in the liver increased both at 24 and 48 h. Expression of MT-I mRNA was activated at 3 h and reached the top at 24 h postburn. The conclusion is that severe thermal injury gives rise to oxidative stress and dramatic enhancement of MT expression could be one of the important compensative mechanisms of natural defense system postburn.

Globin-coupled sensors: a class of heme-containing sensors in Archaea and Bacteria

The recently discovered prokaryotic signal transducer HemAT, which has been described in both Archaea and Bacteria, mediates aerotactic responses. The N-terminal regions of HemAT from the archaeon Halobacterium salinarum (HemAT-Hs) and from the Gram-positive bacterium Bacillus subtilis (HemAT-Bs) contain a myoglobin-like motif, display characteristic heme-protein absorption spectra, and bind oxygen reversibly. Recombinant HemAT-Hs and HemAT-Bs shorter than 195 and 176 residues, respectively, do not bind heme effectively. Sequence homology comparisons and three-dimensional modeling predict that His-123 is the proximal heme-binding residue in HemAT from both species. The work described here used site-specific mutagenesis and spectroscopy to confirm this prediction, thereby providing direct evidence for a functional domain of prokaryotic signal transducers that bind heme in a globin fold. We postulate that this domain is part of a globin-coupled sensor (GCS) motif that exists as a two-domain transducer having no similarity to the PER-ARNT-SIM (PAS)-domain superfamily transducers. Using the GCS motif, we have identified several two-domain sensors in a variety of prokaryotes. We have cloned, expressed, and purified two potential globin-coupled sensors and performed spectral analysis on them. Both bind heme and show myoglobin-like spectra. This observation suggests that the general function of GCS-type transducers is to bind diatomic oxygen and perhaps other gaseous ligands, and to transmit a conformational signal through a linked signaling domain.

Expression and fast-flow purification of a polyhistidine-tagged myoglobin-like aerotaxis transducer

A Co(2+)-affinity, fast-flow perfusion chromatography method to purify a polyhistidine-tagged myoglobin-like aerotaxis transducer HemAT-Hs has been developed. The method relies upon a six-histidine affinity tag fused to the C-terminus and N-terminus of HemAT-Hs for expression in the native host, an extremely halophilic Archaeon Halobacterium salinarum, and in the heterologous host Escherichia coli, respectively. The His-tagged HemAT-Hs can be purified rapidly using either low or high ionic strength buffers. Purified His-tagged HemAT-Hs in high or low salt buffers demonstrated no difference in spectral characteristics and retained reversible oxygen binding capacity. This fast-flow Co(2+)-affinity perfusion chromatography provides a simple method for preparation of halophilic heme containing soluble proteins for biophysical and structural studies.

Observational study of erythrocytic inclusion bodies in farmed Atlantic salmon, Salmo salar L., in the British Isles

An observational study was conducted of farmed Atlantic salmon, Salmo salar L., in the British Isles with regard to intraerythrocytic inclusions and disease prevalence. Intraerythrocytic inclusions were observed to be widespread in Atlantic salmon from farms in Ireland and Scotland. The percentage of fish infected with these inclusions and the intensity of infection were greater in sea stage salmon than those in fresh water. This corresponded with reduced values for haematological parameters (haematocrit, erythrocyte count, haemoglobin, MCV, MCH, MCHC). There appeared to be a significant association between the presence of the intraerythrocytic inclusions and focal cardiomyopathy, although there was no established association with overt clinical disease and the presence of the inclusions. There was also a significant association between the presence of raised splenic haemosiderin and multiple intraerythrocytic inclusions.

Effects of angiotensinogen antisense oligonucleotides on fluid intake in response to different dipsogenic stimuli in the rat

The role of centrally synthesised angiotensinogen in neural mechanisms subserving water drinking in rats was investigated by injecting antisense oligonucleotides complementary to rat angiotensinogen mRNA into the brain with the aim of inhibiting cerebral angiotensinogen synthesis. Phosphorothioate antisense oligonucleotides (18 mer) encompassing the translation start codon were injected into the lateral ventricle of rats and their responses to a number of dipsogenic stimuli tested. These were: intracerebroventricular (i.c.v.) renin, i.c.v. angiotensin II, i.c.v. carbachol, subcutaneous isoproterenol, intravenous hypertonic saline, water deprivation for 24 h or subcutaneous injection of polyethylene glycol. Antisense treatment significantly reduced (by approximately 50%) the volume of water drunk in response to i.c.v. injection of renin or subcutaneous isoproterenol, but did not reduce water intake elicited by the other dipsogenic stimuli. The i.c.v. administration of mismatch, scrambled or sense oligonucleotides did not inhibit water intake. These data suggest that centrally produced angiotensinogen may have a role in neural pathways subserving isoproterenol-induced drinking.

Automated cyanide-free method for haemoglobin determination on Technicon H.1

We have developed a cyanide-free haemoglobin method for our Technicon H.1 counter. By adding 2.5 mmol/l of the ionic surfactant sodium dodecyl sulphate in 154 mmol/l sodium chloride, the haemoglobins are converted to a stable product, denatured globin haemichrome, within the 25 s available on the instrument. The method is as precise and accurate as the original H.1 method, and the reagent is easily made in the laboratory at a very low price. Since the method is relatively safe with regard to waste disposal, the effluent from the counter can be drained into the laboratory sink. The method, a 'SDS-haemichrome method', has now worked very satisfactorily in routine use for a year. Manufacturers of haematological analysers should consider this haemoglobin method for their automated instruments.

The determination of haemoglobin as cyanhaemiglobin or as alkaline haematin D-575. Comparison of method-related errors

In order to compare the accuracy of haemoglobin (Hb) determination methods, the commonly used cyanhaemiglobin (HiCN) method and the recently developed alkaline haematin D-575 (AHD) method (R. Zander, W. Lang & H. U. Wolf (1984) Clin. Chim. Acta 136, 83-93; H. U. Wolf, W. Lang & R. Zander (1984) Clin. Chim. Acta 136, 95-104) were tested with respect to method-related errors such as plasma, cell, and Hb errors. Both methods yield a series of more or less significant errors which generally lead to an overestimation of the Hb concentration in the order of 1%. However, in all three cases of plasma errors, i.e. normal plasma error, plasma error in lipaemic blood, and plasma error in bilirubinaemic blood, the AHD method shows significantly lower values of errors than the HiCN method. In the case of cell errors such as ghost and leukocyte errors, the overestimation of the Hb concentration by the HiCN method is 60% higher than that by the AHD method. In the case of Hb errors such as fetal Hb and carboxy Hb errors, there is a significant overestimation of the Hb concentration by the HiCN method, which amounts 3 min after mixing of blood and HiCN solution to 0.7% in the case of fetal Hb and to 13.2% in the case of carboxy Hb. The latter value yields an overestimation of 1.3%, when 10% carboxy Hb in a blood sample is present. In contrast, there is no detectable overestimation after 3 min in the case of the AHD method. Thus, the AHD method provides a higher accuracy in Hb determination than the commonly used HiCN method.

Field measurement of plasma and erythrocyte cholinesterases

We have optimized Ellman-type plasma and erythrocyte cholinesterase assays for the field determination of pesticide exposure. The assays employ stable, premixed, inexpensive colorimetric reagents and a simplified kinetic measurement procedure using a novel battery-operable light-emitting-diode-source colorimeter (LEDSC). These methods were compared to a field tintometric method for cholinesterase currently in widespread use, using samples from organophosphate-intoxicated hospitalized patients. In comparison to the colorimetric method, the tintometric method was less precise and consistently underestimated the extent of pesticide exposure. Methods for the effective field determination of pesticide exposure using cholinesterase assays are critically evaluated with regard to their practical, biochemical, and medical relevance.

Hemoglobinometry: evaluation of a new method with a stable primary standard

Using purified chlorohemin as a stable standard, a newly described hemoglobinometry method was evaluated. All blood samples as well as chlorohemin gave identical absorption spectra in an alkaline-detergent solution with a broad peak at 575 nm. Both the reagent mixture and the chlorohemin standard were stable for at least 250 days when stored between 8 degrees C and 32 degrees C in brown glass bottles. The new method showed close correlation when compared to the cyanmethemoglobin technique. Compared to the cyanmethemoglobin method the advantages included a stable standard, shorter conversion time, reduced plasma background and improved hemoglobin ligands conversion. We conclude that the new method confers significant advantages over the cyanmethemoglobin method and in particular provides a stable primary standard with a long shelf-life.

Haemoglobinometry on automated haematology analysers

It is generally recognized that the standardized cyanmethaemoglobin (HiCN) method is the preferred method for the determination of haemoglobin in blood. In automated analysers, however, the reaction time available before the photometric measurement is too short. With the Ortho ELT800 we found that the conversion into HiCN took longer than 25 s. More important was the variation of results with the haemoglobin derivatives present in the blood sample. Our experiments suggest that Coulter counters and other automated analysers as well use denaturated globin haemichrome as the end product in their haemoglobin procedure although they profess to use HiCN by the addition of cyanide to the reagents. However, haemichrome is a suitable alternative for automated analysers as the conversion time is very short for all haemoglobin derivatives including HbCO. In the Coulter S Plus III where white cell size distribution analysis and haemoglobin determination are performed in the same solution, the haemoglobin derivative formed shortly after mixing is not a stable one. White cell size analysis and haemoglobin determination should preferably be performed in separate channels with different lysing reagents giving optimal conditions for each determination. Evaluation of the analysers would be easier if the manufacturers would give correct information on the chemistry of the haemoglobin method and state the composition of the reagents used.

Determination of haemoglobin in birds by a modified alkaline haematin (D-575) method

A recently published method for measuring human haemoglobin based on alkaline haematin (Zander et al., Clin. chem. Acta 136, 83-93, 1984) has been adopted for bird samples. The new method yields comparable haemoglobin values with that of a previously used alkaline haematin method. Levels of haemoglobin estimated using alkaline haematin were higher than for cyanhaemiglobin, the reference method for human haemoglobin. This difference is due to the loss of haemoglobin in the cyanhaemiglobin procedure due to insolubility. The values for haemoglobin found by the alkaline haematin method did not vary significantly between a range of bird species. The method overcomes some important deficiencies of the cyanhaemiglobin method, in particular, problems of turbidity and quality control assessment.