Relationship between blood hemoglobin, plasma and tissue iron, muscle heme pigment, and carcass color of veal

In 41 veal calves divided into three groups and fed different levels of dietary iron, blood hemoglobin, plasma iron, liver, spleen, and muscle iron, muscle heme pigment, and carcass muscle color at slaughter were studied. At 45 min postmortem, total carcass color was visually evaluated in the 41 carcasses. In different muscles of the carcasses the color was measured instrumentally using an invasive color measurement method at 45 min postmortem (MCDI score) and a surface color measurement method at 20 h postmortem (Minolta L*, a*, b*, and Chroma scores). Among the three groups, differences (P less than .05) in muscle iron concentrations, muscle heme pigment concentrations, and Minolta a*, b*, and Chroma scores were found. Most striking were the differences in mean iron concentrations in the longissimus thoracis muscles between Groups A (29 micrograms/g DM) and B (44 micrograms/g DM) and in the semimembranosus muscles between Groups A (31 micrograms/g DM) and C (45 micrograms/g DM). The correlations found between Minolta L*, a*, or Chroma score and the iron and heme pigment concentrations in the semimembranosus muscles were high in comparison with those found in the longissimus thoracis and rectus abdominis muscles. Compared with the plasma iron concentration, the blood hemoglobin concentration showed higher correlations with muscle iron and muscle heme pigment concentrations. It can be concluded that different iron concentrations in the milk replacer during the first 7 wk of fattening influence, to some extent, muscle iron and muscle heme pigment at slaughter. However, these differences were not measurable in the overall visual color evaluation of the carcass surface muscles.

A microtitre-based method for measuring the haem polymerization inhibitory activity (HPIA) of antimalarial drugs

The malaria parasite metabolizes haemoglobin and detoxifies the resulting haem by polymerizing it to form haemozoin (malaria pigment). A polymer identical to haemozoin, beta-haematin, can be obtained in vitro from haematin at acidic pH. Quinoline-containing anti-malarials (e.g. chloroquine) inhibit the formation of either polymer. Haem polymerization is an essential and unique pharmacological target. To identify molecules with haem polymerization inhibitory activity (HPIA) and quantify their potency, we developed a simple, inexpensive, quantitative in-vitro spectrophotometric microassay of haem polymerization. The assay uses 96-well U-bottomed polystyrene microplates and requires 24 h and a microplate reader. The relative amounts of polymerized and unpolymerized haematin are determined, based on solubility in DMSO, by measuring absorbance at 405 nm in the presence of test compounds as compared with untreated controls. The final product (a solid precipitate of polymerized haematin) was validated using infrared spectroscopy and the assay proved reproducible; in this assay, activity could be partly predicted based on the compound's chemical structure. Both water-soluble and water-insoluble compounds can be quantified by this method. Although the throughput of this assay is lower than that of radiometric methods, the assay is easier to set up and cheaper, and avoids the problems related to radioactive waste disposal.

Hemozoin production by Plasmodium falciparum: variation with strain and exposure to chloroquine

Synchronized Plasmodium falciparum parasites were grown in erythrocytic culture for measurement of malaria pigment (hemozoin) production using a simple method based on the insolubility of beta-hematin, the principal pigment of hemozoin. In the last 44 h of the life cycle, one strain (chloroquine-susceptible) incorporated an average of 960 pmol of ferriprotoporphyrin IX (FP) from hemoglobin into beta-hematin per 10(6) parasitized erythrocytes. By comparison, another strain (chloroquine-resistant) incorporated 515 pmol of FP into beta-hematin. When exposed to 25 ng of chloroquine per ml of culture medium, chloroquine-susceptible P. falciparum incorporated 240 pmol of FP into beta-hematin per 10(6) parasitized erythrocytes in one intraerythrocytic life cycle. In contrast chloroquine-resistant P. falciparum exposed to 100 ng of chloroquine per ml incorporated 630 pmol of FP into beta-hematin. Thus, chloroquine inhibits hemozoin production in chloroquine-susceptible P. falciparum but not in chloroquine-resistant P. falciparum. On the contrary, sublethal concentrations of chloroquine partially reverse a deficiency of hemozoin production in chloroquine-resistant P. falciparum. These results indicate that the adaptation responsible for chloroquine resistance in P. falciparum prevents the accumulation of toxic FP by preventing chloroquine from uncoupling the processes of hemoglobin degradation and hemozoin production.

Inner filter with carbon quantum dots: A selective sensing platform for detection of hematin in human red cells

Hematin plays a crucial role in various physiological functions, and the determination of hematin in complex biological matrixes is a significant but difficult issue. Considering the unique photophysical/photochemical properties of carbon quantum dots (CQDs) prepared with p-aminobenzoic acid (PABA) and ethanol, a new strategy for the design of fluorescent probes for hematin has been achieved. The proposed sensor array is fabricated based on the inner filter effect (IFE) between hematin and CQDs with phenomenon of selective fluorescence quenching of CQDs which results from the strong absorption of the excitation and emission spectrum of CQDs by hematin. The fluorescence quenching of CQDs is closely related to the amount of hematin and there is a good linear relationship over the range of 0.5-10μM with a detection limit of 0.25μM. What's more, the fluorescence assay has been successfully applied for hematin sensing in healthy human red cells showing this sensing assay has a great potential prospect for detection of hematin in the complex matrixes.

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

A new method for the rapid and accurate measurement of haemoglobin has been developed as an alternative to the conventional cyanhaemiglobin method. This method is based on the conversion of all haeme, haemoglobin, and haemiglobin species into a stable end product by an alkaline solution of a non-ionic detergent ('AHD reagent'). The reaction product, designated as alkaline haematin D-575, is extremely stable and shows a characteristic absorption peak at 575 nm. As compared to the cyanhaemiglobin method, the determination of haemoglobin by alkaline haematin D-575 offers several advantages such as (1) extreme stability of the AHD reagent and the conversion product, (2) decreased conversion time of all haemoglobin species into the end product, (3) decreased amounts of plasma and cell errors, and errors caused by delayed conversion of carboxy- and fetal haemoglobins, and (4) standardisation by a primary standard (purified crystalline chlorohaemin).

Detection of malaria parasites in blood by laser desorption mass spectrometry

A novel method for the in vitro detection of the protozoan Plasmodium, the causative agent of malaria, has been developed. It comprises a protocol for cleanup of whole blood samples, followed by direct ultraviolet laser desorption (LD) time-of-flight mass spectrometry. Intense ion signals are observed from intact ferriprotoporphyrin IX (heme), sequestered by malaria parasites during their growth in human red blood cells. The LD mass spectrum of the heme is structure-specific, and the signal intensities are correlated with the sample parasitemia (number of parasites per unit volume of blood). Parasitemia levels on the order of 10 parasites/microL blood can be unambiguously detected by this method. Consideration of laser beam parameters (spot size, rastering across the sample surface) and actual sample consumption suggests that the detection limits can be further improved by at least an order of magnitude. The influence of experimental factors, such as desorbed ion polarity, laser exposure and fluence, sample size, and parasite growth stage, on the threshold for parasite detection is also addressed.

EPR study of ferric native prostaglandin H synthase and its ferrous NO derivative

Purified prostaglandin H synthase (EC 1.14.99.1) apoprotein, a polypeptide of 72 kDA, was titrated with hemin and EPR spectra of high-spin ferric heme were observed at liquid-helium temperature. With up to one hemin per polypeptide, a signal at g = 6.6 and 5.4, rhombicity 7.5%, evolved owing to specifically bound, catalytic active heme. At higher heme/polypeptide ratios signals at g = 6.3 and 5.9 were observed which were assigned to non-specific heme with no catalytic function. In microsomes from ram seminal vesicles the native enzyme showed the signal at g = 6.7 and 5.2 which could not be increased by the addition of hemin. Cyanide, an inhibitor of the enzyme, reacted at lower concentrations with the specific heme abolishing its signal at g = 6.6 and 5.4. Higher concentrations of cyanide were needed for the disappearance of the signal of non-specific heme. The reduced enzyme reacted with NO and formed two types of NO complexes. A transient complex, with a rhombic signal at gx = 2.07, gz = 2.01 and gy = 1.97, was assigned to a six-coordinate complex. The final, stable complex showed an axial signal at g = 2.12 and g = 2.001 and was assigned to a five-coordinate complex, where the protein ligand was no longer bound to the heme iron. Neither type of signal showed a hyperfine splitting from nitrogen of histidine indicating the absence of a histidine-iron bond in the enzyme. From these results and the similarity of the EPR signal at g = 6.6 and 5.4 to the signal of native catalase (EC 1.11.1.6) we speculated that tyrosinate might be the endogenous ligand of the heme in prostaglandin H synthase.

Tooth discoloration by blood: an in vitro histochemical study

An in vitro model, using a modification of a technique devised by Freccia & Peters, was developed to investigate tooth staining following pulpal haemorrhage. Samples of whole blood, erythrocytes, plasma and platelet concentrate and saline were individually placed in the pulp chambers of groups of five teeth and centrifuged twice daily for 25 min over a period of 3 consecutive days. This confirmed that the blood pigment responsible for the staining was found only in those samples containing erythrocytes. Teeth stained with packed red cells were then prepared for histological examination and subjected to four histochemical tests: (1) benzidine, (2) zinc leuco, (3) Perl's and (4) Turnbull Blue to analyse some of the biochemical changes following haemorrhage into the pulp chamber. These tests showed that, following haemolysis of erythrocytes within dentine, haemoglobin was found either intact or as one of the haematin molecules with no further breakdown of the haem structure and no evidence of any free ferric ions or haemosiderin.

Biochemical characterization of Plasmodium falciparum hemozoin

Hemozoin, the pigment granule which develops within the blood stage food vacuole of the malaria parasite Plasmodium falciparum, was biochemically characterized. Hemozoin was found to be composed of 65% protein, 16% ferriprotoporphyrin-IX (hematin), 6% carbohydrate, and trace amounts of lipid and nucleic acids. The overwhelming majority of the protein component is a mixture of native and denatured human globin non-covalently associated with the metalloporphyrin. Immunoelectron microscopy, employing anti-human hemoglobin as a probe, identified in situ association of hemoglobin with hemozoin. Hemozoin produced within diabetic blood had a higher proportion of carbohydrate, suggesting that the carbohydrate component comes from non-enzymatic glycosylation of hemoglobin.

Clinical associations with objective menstrual blood volume

OBJECTIVE

To determine the association between simple clinical parameters and objective menstrual blood volume.

STUDY DESIGN

A cohort study, in a London teaching hospital. Women complaining of menorrhagia (207) and those who considered their menstruation to be normal (47) were studied. Those with no demonstrable gynaecological pathology had their menstrual blood loss measured using the alkaline haematin technique.

RESULTS

Only 49% of 207 women complaining of menorrhagia had a loss of 80 ml or more. There was an increasing incidence of objective menorrhagia with increasing duration of bleeding and use of more sanitary protection items. Increasing height, age and number of intrauterine pregnancies were all associated with increasing menstrual blood volume. Haemoglobin fell with increasing menstrual blood loss.

CONCLUSIONS

Despite these clinical associations it is difficult to establish the quantity of menstrual bleeding with certainty without an objective assessment.

Purification, crystallization, and characterization of peroxidase from Coprinus cinereus

Peroxidase (donor: H2O2 oxidoreductase [EC 1.11.1.7]) was purified from a culture broth of an inkcap Basidiomycete, Coprinus cinereus S.F. Gray. A single component containing a low amount of carbohydrate was isolated by affinity chromatography on concanavalin A-Sepharose and crystallized from ammonium sulfate solution. The enzyme is an acidic protein (pI 3.5) and consists of a single polypeptide chain having the molecular weight of 41,600 daltons. The enzyme contains one protohemin per molecule and exhibits the characteristic absorption, circular dichroism, and magnetic circular dichroism spectra of a heme-protein. The Coprinus peroxidase forms two characteristic intermediate compounds, I and II, and the rate constants for hydrogen peroxide and guaiacol had similar values to those for higher plant peroxidases. The ferric enzyme formed a cyanide compound with a dissociation constant similar to those for higher plant enzyme, but the dissociation constant of the ferrous enzyme-cyanide was large. The chemical composition of Coprinus peroxidase showed 381 amino acid residues, 1 glucosamine, 3 true sugars, 3 calcium, and 1 non-heme iron other than 1 protohemin. The secondary structure of the fungal enzyme was very similar to that of horseradish peroxidase.

The composition of haemozoin from Plasmodium falciparum

Haemozoin (malaria pigment) was isolated from 2 strains of Plasmodium falciparum cultivated in vitro. The purest preparations contained 41 to 45% ferriprotoporphyrin IX and a glycine-rich polypeptide ('apohaemozoin') of approximately 14 kDa molecular weight which is synthesized by the parasite. In the two strains studied, NF54 and K1, it was calculated that about 15 and 18 iron porphyrin molecules, respectively, were associated with each molecule of apohaemozoin, which contained more hydrophobic amino acid residues in strain K1. One molecule of iron porphyrin was associated with every 9-10 amino acid residues in the haemozoin of both strains. Our observations support the idea that the intraerythrocytic malaria parasite, incapable of cleaving the haem ring, detoxifies the iron porphyrin residuum from haemoglobin digestion in a crystalline complex with a specially synthesized protein.

Hemin levels in culture medium of Porphyromonas (Bacteroides) gingivalis regulate both hemin binding and trypsinlike protease production

Washed cells and Sarkosyl-insoluble outer membrane preparations of the black-pigmented bacteroides Porphyromonas gingivalis W50 bound hemin. The amount of hemin removed from a buffered solution by both cells and outer membranes was significantly larger if bacteria had been grown in broths supplemented with 5 mg of hemin per liter rather than none. Conversely, cells grown without supplemental hemin bound relatively little. However, all preparations bound some hemin. In addition, hemin regulated the production of significantly higher levels of trypsinlike protease by P. gingivalis W50. The nonpigmented variant, W50 BE1, showed no such responses to the levels of hemin in the growth medium.

Aptamer-based label-free method for hemin recognition and DNA assay by capillary electrophoresis with chemiluminescence detection

An aptamer-based label-free approach to hemin recognition and DNA assay using capillary electrophoresis with chemiluminescence detection is introduced here. Two guanine-rich DNA aptamers were used as the recognition element and target DNA, respectively. In the presence of potassium ions, the two aptamers folded into the G-quartet structures, binding hemin with high specificity and affinity. Based on the G-quartet-hemin interactions, the ligand molecule was specifically recognized with a Kd approximately 73 nM, and the target DNA could be detected at 0.1 microM. In phosphate buffer of pH 11.0, hemin catalyzed the H2O2-mediated oxidation of luminol to generate strong chemiluminescence signal; thus the target molecule itself served as an indicator for the molecule-aptamer interaction, which made the labeling and/or modification of aptamers or target molecules unnecessary. This label-free method for molecular recognition and DNA detection is therefore simple, easy, and effective.

Alkaline haematin D-575, a new tool for the determination of haemoglobin as an alternative to the cyanhaemiglobin method. II. Standardisation of the method using pure chlorohaemin

Chlorohaemin with high purity (greater than 99%), a stable and well-defined compound, can be used as a primary standard for the standardisation of a haemoglobin assay based on alkaline haematin D-575 [6]. Dissolved in a solution of 25 g Triton X-100 per litre of 0.1 mol/l NaOH ('AHD solution'), the millimolar absorbance coefficient of the end product (alkaline haematin D-575) is 6.960 +/- 0.046 [l X mmol-1 X cm-1] at 575 nm. Within the range of haemoglobin concentrations of 5 to 25 g/100 ml there is a strong linear relation between chlorohaemin concentration and absorbance with a deviation of less than or equal to 2% from the theoretical values. As compared to the conventional cyanhaemiglobin standard solutions, standardisation with pure chlorohaemin is the method of choice because of the simplicity of the preparation of standard solutions, which can be done in every laboratory, and the stability of both the solid compound chlorohaemin and its solutions in alkaline Triton X-100. For the first time a real standard for quality control in haemoglobinometry is recommended: a concentrated solution which behaves like blood, i.e. the simulation of all steps in haemoglobin determination (dilution and photometry) is possible.

Developmental validation of a multiplex qPCR assay for assessing the quantity and quality of nuclear DNA in forensic samples

Forensic scientists are constantly searching for better, faster, and less expensive ways to increase the first-pass success rate of forensic sample analysis. Technological advances continue to increase the sensitivity of analysis methods to enable genotyping of samples containing minimal amounts of DNA, yet few tools are available that can simultaneously alert the analyst to both the presence of inhibition and level of degradation in samples prior to genotyping to allow analysts the opportunity to make appropriate modifications to their protocols and, consequently, to use less sample. Our laboratory developed a multiplex quantitative PCR assay that amplifies two human nuclear DNA target sequences of different length to assess DNA degradation and a third amplification target, a synthetic oligonucleotide internal PCR control (IPC), to allow for the assessment of PCR inhibition. We chose the two nuclear targets to provide quantity and fragment-length information relevant to the STR amplification targets commonly used for forensic genotyping. The long target (nuTH01, 170-190 bp) spans the TH01 STR locus and uses a FAM-labeled TaqMan probe for detection. The short nuclear target (nuCSF, 67 bp) is directed at the upstream flanking region of the CSF1PO STR locus and is detected using a VIC-labeled TaqManMGB probe. The IPC target sequence is detected using a NED-labeled TaqManMGB probe. The assay was validated on the Applied Biosystems 7500 Real-Time PCR system, which is optimized for NED detection. We report the results of a developmental validation in which the assay was rigorously tested, in accordance with the current SWGDAM guidelines, for precision, sensitivity, accuracy, reproducibility, species specificity, and stability.

Autoantibodies unmasked by redox reactions

Blood from healthy donors was found to contain a variety of autoantibodies after being cultured overnight in commercial blood culture bottles. Paradoxically some autoantibodies in the blood of patients with autoimmune diseases were no longer detectable when similarly cultured. By a process of elimination it was revealed that hemin was responsible for the conversion of antibody-negative blood to antibody-positive blood, as well as for the conversion of antibody-positive blood to antibody-negative blood. By using a purified component system of hemin and immunoglobulin, and an iron-free congener of hemin, we have shown that the appearance and/or disappearance of antibodies occur uniquely in the presence of coordinated iron and in the absence of antioxidants such as vitamin C. The oxidation-reduction (redox) reactions used to demonstrate the appearance and disappearance of autoantibodies have been performed in vitro. Whether the reactions we have observed have a parallel in vivo remains to be determined. It is clear from our findings that normal individuals have immunoglobulin molecules which can exhibit autoantibody binding capacity, and that at least some autoantibodies in autoimmune individuals can have their binding capacity masked by exercise of a natural redox system. These preliminary findings need further investigation but they already hint that some of our apparently well based views on autoimmunity might be expanded to include a role for masked and unmasked autoantibodies.

The alkaline hematin method for measuring menstrual blood loss--a modification and its clinical use in menorrhagia

Direct measurement of menstrual blood loss is the only reliable basis of the diagnosis 'menorrhagia'. We describe modifications of the alkaline hematin method for measuring menstrual blood loss (MBL) which improve the recovery rate from 89 to 98% and make the method more suitable for routine laboratory use. Using this modified method, 5 out of 21 patients (24%) complaining of menorrhagia and scheduled for hysterectomy had an MBL less than 80 ml, which is the upper level of normal MBL.

Effect of temperature on metabolism of Phlebotomus papatasi (Diptera: Psychodidae)

Phlebotomus papatasi (Scopoli) (Diptera: Psychodidae) is the most important vector of Leishmania major, and previous experiments revealed that Leishmania development in the sand fly midgut is significantly affected by temperature. Therefore, we maintained blood-fed P. papatasi females at 23 or 28 degrees C to understand the effect of temperature on bloodmeal digestion and developmental times of this sand fly. At the lower temperature, the metabolic processes were slower and developmental times were longer: defecation, oviposition, and egg hatch started later and took longer to complete. Also, the mortality of blood-fed females was significantly lower. The defecation of bloodmeal remains was delayed for 12-36 h at 23 degrees C compared with the group maintained at 28 degrees C. Such delay would provide more time for Leishmania to establish the midgut infection and could partially explain the increased susceptibility of P. papatasi to Leishmania major at 23 degrees C. In both experimental groups, blood-fed females laid similar numbers of eggs (mean 60 and 70, maximum 104 and 115 per female). Egg numbers were positively correlated with the amount of hematin excreted in feces of ovipositing females. In parallel experiments, autogeny was recorded in 8% of females. The autogenous egg batches were smaller (mean, 12; range, 1-39), but they all produced viable larvae.

A spectrophotometric method for estimating hemin in biological systems

Hemin chlorides exhibit two absorption maxima in the Soret region, one at about 360-380 nm (S' band) and the other between 400 and 430 nm (S band). We present here a simple and fast spectrophotometric assay to determine concentration of hemin between 1.15 and 9.20 microM employing the Soret region (S' band) as a reference. In this method the hemin is quantitatively extracted from biological materials by acidified chloroform. By recording the absorbance of the chloroform extract at its maximum peak at 388, 450, and 330 nm and applying the correction formula A(c)=2A388-(A450+A330), a very good linear correlation between the A(c) and the concentration of hemin is attained. The method can be used to estimate hemin in the presence of protein (0.06-5.00 mg/ml) and porphyrin (0.19-2.97 microM). Compared with the pyridine hemochromogen method, the assay reported here is highly reproducible, with 15- to 30-fold more sensitivity, and it allows the quantification of four times lower hemin concentrations.

Haemoglobin during pregnancy: relationship to erythropoietin and haematinic status

OBJECTIVE

To investigate the effect of haematinic status on erythropoietin throughout pregnancy in order to assess whether haematinic supplementation is appropriate for all pregnant women or should be reserved for individuals in whom deficiency has been identified.

METHODS

A prospective, repeated-measures, longitudinal study of 263 women enrolled at an antenatal clinic in a district general hospital who received standard obstetric management including haematinic supplements. Haematological indices, iron status, folate and B12 status, and erythropoietin levels were measured by standard methods at scheduled intervals throughout pregnancy. The relationships between the measurements were analysed using statistical models which took into account the serial correlation between repeated measurements on the same individuals.

RESULTS

Erythropoietin levels rose throughout pregnancy from a mean of 22.8 mU/mL at booking to 43.7 mU/mL at 38 wk. There was a significant relationship between erythropoietin levels and haemoglobin, ferritin, TIBC and folate. The relationship was strongest between erythropoietin and haemoglobin. Erythropoietin levels were influenced by parity but not maternal age.

CONCLUSION

Haematinic levels, particularly iron are related to the rise in serum EPO which occurs during pregnancy. Therefore, haematinic deficiency in pregnancy will result in increased stimulation of erythroid progenitor cells by erythropoietin. While haematinic supplementation is not always prescribed throughout pregnancy, haematinic status must be assessed on an individual basis and supplementation provided as required.

Quantitative determination of heme for forensic characterization of bacillus spores using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

A quantitative method was developed for the determination of heme (ferriprotoporphyrin IX) using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). The method was designed for forensic characterization of the use of blood agar in preparation of Bacillus spores. An alkali wash of 0.3 M ammonium hydroxide was used to solubilize heme from spore samples. The wash was concentrated and analyzed by MALDI-TOFMS. Experimental parameters were optimized to obtain the best signal intensity, maximize signal reproducibility, and improve day-to-day repeatability of the measurement. Sinapinic acid was found to be the best matrix. A sandwich sample preparation protocol was determined to increase the shot-to-shot and point-to-point reproducibility of the measurement. Cobalt(III) protoporphyrin was used as an internal standard and the analyte/internal standard ratio responses from solutions of known concentrations were used to construct a calibration curve (R(2) = 0.993). Limits of detection and quantitation for heme were calculated to be approximately 0.4 (200 fmol) and 0.8 microM (400 fmol), respectively. Spore samples prepared on blood agar and nonblood agar were analyzed using the method. Heme was detected at a concentration of approximately 0.3 ng/mg of spore on samples prepared on blood agar and purified by extensive washing. Heme was not detected on spore samples prepared without blood.

Purification and some properties of malarial pigment

Malarial pigment from erythrocytes infected with Plasmodium berghei was purified by treatment with sodium dodecyl sulphate solution, followed by incubation with Pancreatin. The purified pigment retained the apparently crystalline form of pigment within the parasite, rotated polarised light and had the same solubility characterisation as crude malarial pigment. It contained about 1% iron, all of which could be accounted for in terms of haemin. The iron of the pigment molecule is oxidised by the parasite to the ferric state.