Photooxidation of skeletal muscle sarcoplasmic reticulum induces rapid calcium release

The photooxidizing xanthene dye rose bengal is shown to induce rapid Ca2+ release from skeletal muscle sarcoplasmic reticulum (SR) vesicles. In the presence of light, nanomolar concentrations of rose bengal increase the Ca2+ permeability of the SR and stimulate the production of singlet oxygen (1O2). In the absence of light, no 1O2 production is measured. Under these conditions, higher concentrations of rose bengal (micromolar) are required to stimulate Ca2+ release. Furthermore, removal of oxygen from the release medium results in marked inhibition of the light-dependent reaction rate. Rose bengal-induced Ca2+ release is relatively insensitive to Mg2+. At nanomolar concentrations, rose bengal inhibits [3H]ryanodine binding to its receptor. beta,gamma-Methyleneadenosine 5'-triphosphate, a nonhydrolyzable analog of ATP, inhibits rose bengal-induced Ca2+ release and prevents rose bengal inhibition of [3H]ryanodine binding. Ethoxyformic anhydride, a histidine modifying reagent, at millimolar concentrations induces Ca2+ release from SR vesicles in a manner similar to that of rose bengal. The molecular mechanism underlying rose bengal modification of the Ca2+ release system of the SR appears to involve a modification of a histidyl residue associated with the Ca2+ release protein from SR. The light-dependent reaction appears to be mediated by singlet oxygen.

Nitrendipine is a potent inhibitor of the Ca(2+)-activated K+ channel of human erythrocytes

Nitrendipine, a classical blocker of L-type Ca2+ channels, is shown to be a potent inhibitor of the Ca(2+)-activated K+ channel of human erythrocytes. In erythrocytes suspended in a solution with physiological Na+ and K+ concentrations and in which the channel was activated using the Ca2+ ionophore ionomycin, nitrendipine inhibited K+(86Rb+) influx with an I50 of around 130 nM. Similar results were obtained for K+(86Rb+) efflux, and for K+(86Rb+) influx into cells suspended in a high-K+ medium.

Assessment of Diesse Ves-matic automated system for measuring erythrocyte sedimentation rate

Measurement of the erythrocyte sedimentation rate (ESR) using a closed tube system reduces the biohazard risk to laboratory staff. The Diesse Ves-matic system offers manual or vacuum collection of blood into plastic tubes, automated mixing of the sample, and automated reading of the end point after 20 minutes of sedimentation. This system was compared with the 1977 Westergren ESR method of the International Council for Standardization in Haematology (ICSH) and with the 1988 ICSH undiluted ESR method. Manually collected Ves-matic samples showed good agreement with ICSH values, although there was a tendency to false low results at low ESR values which may represent dilution of plasma protein with excess citrate. Vacuum collected Ves-matic samples also showed good agreement with ICSH values, although there was a tendency to false high results which may reflect a change in the blood: citrate ratio caused by loss of anticoagulant diluent or vacuum from plastic tubes during storage. The Diesse Ves-matic system incorporates several improvements over previous technology and offers a safer, quicker, and more standardised ESR.

Checking of unit dose cassettes by pharmacy technicians at three Minnesota hospitals

A pilot project in which pharmacy technicians were trained to check unit dose cassettes filled by other technicians is described. With the approval of the state board of pharmacy, the Minnesota Society of Hospital Pharmacists (MSHP) conducted the nine-month project in three hospitals with different types of unit dose drug distribution systems. Twenty-seven technicians underwent didactic and practical training and were then validated as checkers if they scored 99.8% accuracy in checking carts into which errors had been deliberately introduced by the pharmacist auditor. The performance of validated technicians was audited monthly, and failed audits had to be repeated. Participating technicians did not check the preparation of first doses or extemporaneously prepared doses. In 100,000 doses audited, 60 errors by the validated checkers were identified. Of six technicians who failed a monthly audit, five passed a repeat audit. Pharmacists at the participating hospitals documented time they spent on clinical activities that would have been spent checking cassettes. In December 1990 a one-year extension of the project, expanded to 10 hospitals, began. With strict quality control measures, specially selected and trained pharmacy technicians performed unit dose cassette checking with an accuracy of at least 99.94%.

Evaluation of a 200 mm long vacuum aspiration tube for measurement of erythrocyte sedimentation rate

The ESrT-system 200 comprises a 215 mm long vacuum aspiration venepuncture tube which contains anticoagulant diluent for the measurement of the erythrocyte sedimentation rate (ESR) without direct handling of the blood sample. This combines the advantage of a tube of "Westergren" length with a reduction in biohazard risk. Blood from 160 patients (ESR range 2-135 mm/first hour) was tested in parallel with the selected Westergren ESR method of the International Committee for Standardization in Haematology (ICSH) and a close correlation (r = 0.967) between the two methods was obtained. A second Westergren ESR, using anticoagulated but undiluted blood, was measured on 58 specimens to give an ICSH "expected" ESR. The ESrT-system 200 result was within 12 mm/first hour of the "expected" result for 91% of the specimens. This new ESR system is simple to use, does not require mathematical correction of the ESR reading for tube length, and gives results that are comparable with those obtained with the ICSH Westergren method.

KCl cotransport in HbAA and HbSS red cells: activation by intracellular acidity and disappearance during maturation

Low intracellular pH was shown to be a potent activator of the KCl cotransport system in HbSS red cells, and in reticulocyte-rich fractions of HbAA red cells. Rheological experiments indicated that cell dehydration via the KCl cotransporter in response to low pH decreased the filterability of HbSS red cells. In vitro maturation experiments showed that the KCl cotransport system was rendered cryptic rapidly, in contrast to choline transport, and serine transport via system ASC, which disappeared much more slowly.

Postural consistency in skilled archers

The consistency of an archer's postural set at the moment of loose (arrow release) is commonly perceived to be an important determinant of success. The coach seeks, among other things, to provide the archer with information about postural consistency, details of which he acquires by eye or occasionally by video-recordings. The gains that might be achieved from more precise information are examined here. Nine skilled archers, classified into either skilled or elite groups according to their officially computed handicap, were continuously monitored and measured with a three-dimensional co-ordinate analyser (Charnwood Dynamics Coda-3 Scanner) while shooting two ends (series) of three arrows each. Considerable variability was observed in the precision with which the positions of head, elbow and bow at the moment of loose were replicated by archers of similar levels of skill. These results are interpreted to suggest that precise postural consistency may not be the primary feature distinguishing between the performance of archers at the higher skill levels.

Red cell deformability and haematological disorders

Blood rheology is the science of the flow and deformation of blood. Clinically, blood rheology is important because circulatory resistance has two major components, vascular and rheological. In large vessels, blood rheology should be considered in terms of bulk flow, the viscosity of blood depending mainly on red cell concentration and plasma viscosity and, to a lesser extent, on red cell deformability and aggregation. In the microcirculation, where cells must deform to pass through narrow capillaries, cellular rheology (i.e. the deformability of individual cells) is a major determinant of resistance to flow. This ability to deform is also a determinant of the cell's survival time in the circulation. The deformability of the red cell is essentially linked to its structure (i.e. its cellular geometry, membrane properties and cytoplasmic viscosity); thus structural abnormalities, as found in some haematological disorders, can be expected to affect blood flow in the microcirculation and/or red cell lifespan. Blood rheology is a relatively new discipline as applied to the practice of haematology. In 1985 the International Committee for Standardization in Haematology (ICSH) established an Expert Panel on Blood Rheology which has subsequently issued guidelines on the measurement of blood viscosity and erythrocyte deformability and on tests such as erythrocyte sedimentation rate and plasma viscosity that are used to monitor the acute phase response in inflammatory disease. Rheological methods now have sufficiently good sensitivity and specificity for their application to a wide variety of clinical disorders. This review illustrates their potential application to haematological disorders that cause abnormal deformability of red cells.

Object relations in borderlines, depressives, and normals: an examination of human responses on the Rorschach

Recently, researchers and clinicians have become increasingly interested in diagnostic distinctions between borderline and mood disorders. Object relations theory provides a useful framework for the comparison of these two overlapping diagnostic categories. In our study, a measure of object relations as represented on the Rorschach, developed by Blatt, Brenneis, Schimeck, and Glick (1976), was applied to data produced by borderline and depressive inpatients and by normal comparison subjects. Portions of the Blatt measure that tap the subject's experience of human action and interaction distinguish among the three diagnostic groups. Specifically, borderlines tend to understand human action as more highly motivated and human interaction as more malevolent in nature than do either depressive or normals. The data indicate that borderlines experience the object-relational world in a way that is fundamentally different from the way normals and depressives perceive it. Implications are discussed for theories of borderline object relations.

Technological advances in blood rheology

The science of blood rheology (study of the flow and deformability of blood) is of increasing practical importance to the investigation of blood disorders. In diagnostic laboratories, rheological tests such as the erythrocyte sedimentation rate, zeta sedimentation ratio, and plasma viscosity are used to monitor patients with an acute-phase response of greater than 24 h duration. In sickle-cell anemia, new methods for measuring erythrocyte deformability can be used to investigate the pathogenesis of vaso-occlusion, to test potential anti-sickling drugs, and to monitor drug efficacy in clinical trials. Genetic defects in the structure of the red cell membrane can have rheological consequences, monitoring of which may be useful for diagnosis. Rheological analysis of red cells infected by Plasmodium falciparum has indicated that their abnormal flow behavior may be an important pathological factor in malaria. Finally, the flow behavior of white blood cells, particularly neutrophils, is also important, as these cells, once activated, have the potential to occlude microvessels. The authors have reviewed the laboratory methodology and clinical applications that have led to recent advances in these aspects of blood rheology.

Bepridil protects sickle cells against the adverse rheological effects of cyclical deoxygenation

Calcium influx into sickle cells, with consequential activation of the Ca2(+)-activated K+ efflux (Gardos) channel, is a potential cause of cellular dehydration and loss of deformability. Bepridil, a recently described inhibitor of the Gardos channel, was found at pharmacological concentration (1 mumol/l) to inhibit significantly (P less than 0.01) the loss of deformability when sickle cells were subjected to cycles of oxygenation-deoxygenation for 15 h at 37 degrees C. Bepridil also inhibited significantly (P less than 0.005) the formation of irreversibly sickled cells. Drugs that preserve the K+ and therefore water content of erythrocytes are of potential value for hydrotherapy of sickle cell disease.

Efficacy of tests used to monitor rheumatoid arthritis

The relative efficacy of clinical and laboratory tests used to monitor disease activity in rheumatoid arthritis was determined by consensus analysis in a study of 21 patients treated for 6 months. Erythrocyte sedimentation rate (ESR), which is influenced by the anaemia of chronic disease and by variation in the blood concentration of acute-phase proteins, was the most effective single test. ESR was a better guide to disease severity than measurement of plasma viscosity, serum C-reactive protein, and serum orosomucoid--tests that reflect the blood concentration of acute-phase proteins only. Clinical tests performed poorly unless combined with laboratory data in a numerical index. Consensus analysis can be used to assess the efficacy of clinical and laboratory tests and to identify redundant tests.

Acquired immunodeficiency syndrome

A report entitled "Kaposi's Sarcoma and Pneumocytosis Carinii Pneumonia among homosexual men in New York City and California" in the MMWR in July 1981 alerted the world to the appearance of a completely new disease. The opportunistic infections and cancers occurring in these patients had previously only been seen in patients who were immunosuppressed. Homosexual men were the first as a major risk group to be identified. Others quickly followed. The pattern of occurrence clearly indicated an infectious agent as the likely cause, and within two years the virus had been identified in Europe and the USA. In Europe it was named Lymphadenopathy Associated Virus (LAV) by Montagnier its discover, and in the USA, Human T cell Lymphotrophic Virus III (HTLV III). It is now known as Human Immunodeficiency Virus (HIV).

Erythrocyte heterogeneity in sickle cell disease: effect of deoxygenation on intracellular polymer formation and rheology of sub-populations

Erythrocytes from 12 patients with homozygous sickle cell disease in the steady state were fractionated on a Percoll-Stractan density gradient. Erythrocyte deformability was measured by initial-flow-rate filtration through pores of 5 microns diameter and erythrocyte polymer content was calculated as a function of oxygen saturation. Density fractionated sub-populations of sickle cells showed distinct rheological characteristics, the filterability of dense cells being impaired by minimal oxygen desaturation with the apparent formation of little or no intracellular polymer. Lighter cell fractions required a greater degree of deoxygenation and polymer formation to impair deformability, although this occurred prior to morphological sickling. Dense cells therefore exert a disproportionate effect on blood rheology in sickle cell disease and are likely to have an adverse rheological effect in vivo at arterial oxygen tension.

Pharmacological modification of oxygen affinity improves deformability of deoxygenated sickle erythrocytes: a possible therapeutic approach to sickle cell disease

1. The formation of polymerized haemoglobin S in sickle cells is critically dependent on the concentration of deoxygenated haemoglobin so that compounds which increase the oxygen affinity of haemoglobin S are potential anti-sickling agents. 2. BW12C [5-(2-formyl-3-hydroxyphenoxy)pentanoic acid] and BWA589C [4-(2-formyl-3-hydroxyphenoxymethyl)benzoic acid] are aromatic benzaldehydes that cause a dose-dependent left-shift of the oxygen saturation curve of haemoglobin S by stabilization of its oxy-(R)-conformation. 3. A 5 micron pore filtration method, which is highly sensitive to polymerization of haemoglobin S, was used to demonstrate a significant improvement in the deformability of deoxygenated sickle erythrocytes at concentrations (0.75-1.5 mmol/l] of BW12C and BWA589C that are achievable in vivo. Both compounds may therefore be of value for the treatment of sickle cell disease. 4. Filtration of sickle cells through pores of 5 microns diameter is a sensitive technique for evaluating the rheological effects of potential anti-sickling compounds.

Effect of polymerization tendency on haematological, rheological and clinical parameters in sickle cell anaemia

The polymerization tendency of sickle haemoglobin was estimated as a function of oxygen saturation in 30 patients with homozygous sickle cell anaemia. The deformability of their erythrocytes was also measured, by initial-flow-rate filtration at 37 degrees C through pores of 5 microns diameter, and clinical severity was assessed using a visual analogue scale. By means of partial correlation analysis, it was found that correlations between haematological, rheological, and clinical parameters in sickle cell anaemia could be explained on the basis of an association of each variable with polymerization tendency. Patients with the greatest tendency to form polymer had the least deformable erythrocytes and perceived their disease to be more severe as judged by the visual analogue scale. Polymer formation also appeared to be a determinant of the number of dense cells which, in turn, determine haemolytic rate and erythrocyte deformability.

Evaluation of sealed vacuum extraction method (Seditainer) for measurement of erythrocyte sedimentation rate

A sealed vacuum extraction method (Seditainer) for determining the erythrocyte sedimentation rate (ESR) was compared with the standard Westergren ESR technique. The Seditainer method was particularly easy to use, showed acceptable precision, reduced the biohazard risk to laboratory staff and, on storage of sealed blood specimens for 24 hours at 4 degrees C, gave ESR values that had decreased by a mean of only 1.9% (95% CI + 0.2 to -4.0%). Seditainer tubes are shorter (100 mm) than Westergren tubes (200 mm) and this reduced test sensitivity at ESR values above 55 mm/first hour. After application of the manufacturer's correction formula to adjust for tube length there was improved correlation (n = 150, r = 0.936, p less than 0.001), but still considerable scatter, between the Seditainer and Westergren results. Seditainer ESR values above 55 mm/first hour should therefore be regarded as semiquantitative. This vacuum extraction method offers a simple and safe technique for measuring the ESR and specimens can be stored overnight at 4 degrees C.

Automated measurement of plasma viscosity by capillary viscometer

Plasma viscosity has several advantages over the erythrocyte sedimentation rate as a measurement of an acute phase response of more than 24 hours' duration. A new capillary viscometer (Coulter Viscometer II), which gives an automated measurement of plasma viscosity, was compared with the selected manual method (Harkness viscometer) of the International Committee for Standardization in Haematology. Automated measurement of plasma viscosity at 25 degrees C showed close correlation (r = 0.979, p less than 0.002) with the selected method for 160 specimens of plasma. Satisfactory precision both within batch and between batch (coefficients of variation of 1.7% or less) was obtained at viscosity values up to 5.7 mPa.s. There was no detectable carry over between samples and viscosity values were corrected adequately for ambient temperature for the range 15-32 degrees C. Careful daily cleaning was required to prevent accumulation of protein within the automatic sampling valve of the instrument. Automated measurement of plasma viscosity is an attractive alternative to measurement of the erythrocyte sedimentation rate.

Laboratory tests for monitoring prophylactic exchange transfusion in pregnancy complicated by sickle cell disease

Prophylactic exchange transfusion is of uncertain value in pregnancy complicated by sickle cell disease (SCD), and there is a lack of laboratory tests to monitor its effect and determine the optimal number and frequency of transfusions. In a prospective study of four consecutive pregnancies complicated by SCD, the product of the PCV and percentage of haemoglobin S gave a 'sicklecrit' value that showed a significant (P less than 0.01) improvement following transfusion. Erythrocyte filterability through pores of 5 microns diameter also improved significantly (P less than 0.05) whereas whole blood viscosity did not, owing to the overriding effect of the increase in PCV. Measurement of sicklecrit and erythrocyte filterability, reflecting blood rheology in large and small vessels respectively, may therefore be used to monitor the effects of exchange transfusion in SCD.

Adenine nucleotides stimulate oxidation-induced calcium efflux from sarcoplasmic reticulum vesicles

Micromolar concentrations of copper (Cu2+) and cysteine induce rapid efflux of calcium from sarcoplasmic reticulum (SR) vesicles. This effect appears to be due to a Cu2+-catalyzed oxidation of the added cysteine to a critical sulfhydryl group on the release protein from sarcoplasmic reticulum (J. L. Trimm, G. Salama, and J. J. Abramson (1986) J. Biol. Chem. 261, 16092-16098). The data presented here indicate that adenine nucleotides synergistically stimulate copper/cysteine (oxidation)-induced calcium efflux from SR vesicles. The order of effectiveness in stimulating calcium efflux is ATP greater than AMP-PCP greater than cAMP greater than AMP greater than adenine approximately NAD approximately NADH. Non-adenine-containing nucleotides such as GTP, CTP, UTP, and ITP and the high energy phosphate compound, acetyl phosphate, were ineffective in stimulating oxidation-induced calcium efflux. The relative effectiveness of various adenine nucleotides in stimulating calcium-induced calcium efflux and oxidation-induced calcium efflux are identical, suggesting that a common mode of action is involved when calcium release is triggered by either method. The stimulatory effect of the adenine nucleotides on oxidation-induced efflux is independent of external magnesium concentration and independent of the magnesium gradient across the SR membrane.

Polymerization of sickle cell hemoglobin at arterial oxygen saturation impairs erythrocyte deformability

We have examined the filterability of sickle erythrocytes, using an initial-flow-rate method, to determine whether sufficient hemoglobin S polymer forms at arterial oxygen saturation to adversely affect erythrocyte deformability. The amount of intracellular polymer was calculated as a function of oxygen saturation to estimate the polymerization tendency for each of eight patients with sickle cell anemia (SCA). Progressive reduction of oxygen tension within the arterial range caused a sudden loss of filterability of SCA erythrocytes through 5-micron-diam pores at a critical PO2 between 110 and 190 mmHg. This loss of filterability occurred at a higher PO2 than did morphological sickling, and the critical PO2 correlated significantly (r = 0.844-0.881, P less than 0.01) with the polymerization tendency for each patient. Study of density-gradient fractionated cells from four SCA patients indicated that the critical PO2 of dense cells was reached when only a small amount of polymer had formed, indicating the influence of this subpopulation on the results obtained for unfractionated cells. Impairment of erythrocyte filterability at high oxygen saturation (greater than 90%) suggests that small changes in oxygen saturation within the arterial circulation cause rheological impairment of sickle cells.

Oxpentifylline and cetiedil citrate improve deformability of dehydrated sickle cells

Erythrocytes from 14 patients with homozygous sickle cell anaemia were treated with the calcium ionophore A23187 to induce loss of cellular potassium and water. The dehydrated cells showed a decrease in filterability (loss of deformability) through pores of 5 micron diameter. Oxpentifylline and cetiedil citrate, which preserve erythrocyte cation and water content, had a significant (p less than 0.01) protective effect against loss of deformability at a concentration of 1 mumol/l. Oxpentifylline showed no adverse effect on the rheology, morphology, or haemolysis of sickle cells at concentrations up to 500 mumol/l. Drugs that act on the erythrocyte membrane to maintain cell hydration are of potential rheological benefit in sickle cell anaemia.

Rheological effects of bed rest in sickle cell disease

A serial rheological study in two patients with homozygous sickle cell disease whose leg ulcers healed as a consequence of bed rest showed an improvement in erythrocyte deformability (filterability) associated with evidence of decreased haemolysis and a fall in the number of irreversibly sickled cells. This rheological improvement may aid the healing of leg ulcers by increasing blood flow in the ulcer base. The effects of bed rest on the rheology of sickle cell disease should be taken into account in future studies of vaso-occlusive crisis.

Rheology of the sickle cell disorders

The sickling process causes secondary changes in cell shape, size, cation and water content, and membrane structure that contribute to the impairment of intrinsic cell deformability (Figure 2). This rheological defect is partially compensated by a low haematocrit, which moderates the rise in whole-blood viscosity, and by a rise in cardiac output which increases capillary flow velocity (Berger and King, 1982). A delicate balance exists between these mechanisms and any local disturbance of this balance by pathological changes in factors extrinsic to the sickle cell (Figure 2) can precipitate vaso-occlusion. There is still considerable controversy over the site (arteriolar, capillary, or venular) of vaso-occlusion, the type of sickle cell (reversibly sickled or irreversibly sickled) that is primarily involved, and the relative importance of extra-erythrocytic precipitating factors such as stasis, hypoxia, hyperosmolality, acidosis, alteration in temperature, acute-phase rise in plasma proteins and leukocytes, prothrombotic changes in coagulation factors and platelets, and adhesion of blood cells to vascular endothelium (Figure 2). A low-grade hypercoagulable state has been described in patients with SS (Leichtman and Brewer, 1978; Richardson et al, 1979) which may be related to the procoagulant effect of the shift of phosphatidyl serine to the outer lipid bilayer of the sickle cell (Chiu et al, 1981; Franck et al, 1985). Platelets appear to accumulate at sites of vaso-occlusion (Siegel et al, 1985) and their migration to the vessel wall may be enhanced by the presence of poorly deformable erythrocytes (Aarts et al, 1984). Endothelial cell damage in the arterial or venous circulation may also contribute (Klug et al, 1982). Thus vaso-occlusion appears to result from a complex interaction between blood cells, plasma proteins and endothelium and any one of several precipitating factors may disturb the fragile steady state and cause a painful crisis. The study of sickle cells by rheological methods has considerable potential for investigating the pathophysiology of vaso-occlusive episodes in the SCD and for monitoring, both in vitro and ex vivo, the efficacy of antisickling compounds. Because of the multiple intrinsic and extrinsic factors that contribute to the rheological defect, it is not yet known which of these should be the primary target for an antisickling agent. In-vitro rheological studies in which different metabolic stresses can be applied to intact sickle cells in the presence of a putative antisickling drug should help to answer this question.(ABSTRACT TRUNCATED AT 400 WORDS)

Acute abdominal distension following Cryptosporidium infection

Two children, aged 15 months and 3 years, developed abdominal distension following proven Cryptosporidium enteritis. Both required readmission to hospital and both improved rapidly, one spontaneously and one with the help of an enema. The association of abdominal distension and Cryptosporidium infection has not been described previously.

Induction of siderophore activity in Anabaena spp. and its moderation of copper toxicity

Growth of Anabaena sp. strain 7120 (in the absence of chelators or added iron) was inhibited by the addition of 2.1 to 6.5 microM copper and was abolished by copper concentration of 10 microM or higher. When the copper was chelated to schizokinen (the siderophore produced by this organism in response to iron starvation), the toxic effects were eliminated. Analysis of culture filtrates showed that the cupric schizokinen remains in the medium, thereby lowering the amount of copper taken up by the cells. Although this organism actively transports ferric schizokinen, it apparently does not recognize the cupric complex. Thus, Anabaena sp. is protected from copper toxicity under conditions in which siderophore is being produced. For cells grown in low iron, the accumulation of extracellular schizokinen was observed to parallel cell growth and continue well into stationary phase. The actual iron status of the organism was monitored by using iron uptake velocity as an assay. Cultures grown on 0.1 microM added iron were found to be severely iron limited upon reaching stationary phase, thus explaining the continued production of schizokinen. These data show that the siderophore system in Anabaena spp. has developed primarily as a response to iron starvation and that additional functions such as alleviation of copper toxicity or allelopathic inhibition of other algal species are merely secondary benefits.

Painful sickle cell crises precipitated by stopping prophylactic exchange transfusions

A patient with homozygous sickle cell disease showed a reduced incidence of painful crises as a result of regular exchange transfusion, but on three occasions when transfusion treatment was interrupted, a painful crisis occurred. Onset of painful crisis was associated with raised packed cell volume (PCV) or percentage of haemoglobin S (HbS%), or both. Measurement of whole blood viscosity using in vitro mixtures of blood group compatible normal (AA) and sickle (SS) cells showed that above an HbS of 25% any increase in PCV caused a disproportionate increase in whole blood viscosity. These clinical observations and laboratory data suggest that when regular exchange transfusions are terminated both HbS% and PCV should be carefully monitored. Prophylactic venesection should be considered for patients who maintain their PCV after transfusion as HbS% rises.

Unfolding of iron and copper complexes of human lactoferrin and transferrin

1. Human lactoferrin and transferrin are capable of binding two iron or copper ions into specific binding sites in the presence of bicarbonate. 2. Urea and several alkyl ureas have been effective in unfolding these metal-protein complexes. 3. Biphasic transitions are observed for the unfolding of each of the metal complexes of these proteins as determined by direct visible spectroscopy suggesting the release of iron(III) and Cu(II) ions from both of these metal-binding proteins during the unfolding process. 4. Greater stabilization and increased resistance to protein unfolding is observed for all iron(III) complexes compared to Cu(II) complexes of lactoferrin and transferrin as determined by isothermal unfolding and thermal denaturation. 5. Relative stabilization of the different metal-protein complexes investigated within this study were determined to be as follows: Lf-Fe(III) greater than Lf-Cu(II); Tf-Fe(III) greater than Tf-Cu(II), and Lf-Fe(III) greater than Tf-Fe(III); Lf-Cu(II) greater than Tf-Cu(II).

Intrinsic factors that influence measurement of erythrocyte deformability

The efficiency of rheological tests for measuring erythrocyte deformability is a function of test specificity and test sensitivity. Recent improvements in both specificity and sensitivity have revealed that rheological measurements of erythrocyte deformability are affected by the volume, haemoglobin concentration, and shape of the test erythrocytes. This applies both to filtration methods, using pores of 3-5 micron diameter, and to the measurement of erythrocyte elongation by laser diffractometry. Erythrocyte indices and morphology should therefore be measured routinely in both patients and controls so that the values for these intrinsic factors can be correlated with the results of rheological measurements in all published studies.

Ranking of laboratory tests by consensus analysis

A new analytical technique (consensus analysis) was devised to assess the performance of laboratory tests that are commonly used to monitor the acute and chronic phases of inflammatory disease. On thirty-one tests carried out monthly for 7 months in seventeen patients with rheumatoid arthritis, the consensus analysis procedure ranked plasma viscosity and erythrocyte sedimentation rate in a tie for first place. Measurement of the acute-phase serum protein orosomucoid ranked third. Consensus analysis has the potential to reduce laboratory costs by identifying the most useful tests; it also promises to be helpful in the design of new laboratory tests that are more sensitive and specific.

Effects of hyperglycaemia and sorbitol accumulation on erythrocyte deformability in diabetes mellitus

Erythrocyte deformability was studied in a total of 83 poorly controlled diabetics (mean blood glucose 12.2 mmol/l) who were divided into three groups, each with matched healthy controls. There was no appreciable difference between diabetics and matched controls regarding the filtration of erythrocytes through 3 micron diameter straight channel pores (25 diabetics) or tortuous channel pores (28 diabetics), or for the measurement of erythrocyte elongation over a range of osmolalities in the Ektacytometer (30 diabetics). When erythrocytes from 17 additional diabetics and 17 healthy controls were incubated for two hours at 37 degrees C in hyperglycaemic (50 mmol glucose/l) buffer, however, there was a considerable reduction in erythrocyte filterability for both diabetics and controls in parallel with an increase in erythrocyte sorbitol concentration. This loss of filterability was prevented by the addition of an aldose reductase inhibitor (Sorbinil). High glucose concentrations (congruent to 50 mmol/l) impair the filterability of erythrocytes through 3 micron pores, and the intracellular accumulation of sorbitol in poorly controlled outpatients is therefore unlikely to have a major adverse effect on erythrocyte rheology in diabetes mellitus.

Blood rheology and proliferative retinopathy in homozygous sickle cell disease

Some haematological and rheological features were compared in 27 age and sex matched pairs of patients (15 male, 12 female) with homozygous sickle cell (SS) disease with and without proliferative sickle retinopathy (PSR). Significant haematological differences between the groups were a higher haemoglobin and a lower fetal haemoglobin in PSR positive males and a higher MCHC in PSR positive females. The plasma viscosity and characteristics of erythrocyte filterability did not differ between those with and those without PSR, although PSR positive males had a significantly higher whole blood viscosity when measured at high shear and at the patient's own packed cell volume.