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Biomedical subjects

S N Wickramasinghe

Publications and source records attributed to S N Wickramasinghe.

At least 55 records · Page 3Linked to original sources
PubMed1996

Composition of the intra-erythroblastic precipitates in thalassaemia and congenital dyserythropoietic anaemia (CDA): identification of a new type of CDA with intra-erythroblastic precipitates not reacting with monoclonal antibodies to alpha- and beta-globin chains.

Ultrathin sections of bone marrow cells from two patients with homozygous beta-thalassaemia, two patients with haemoglobin H (HbH) disease, a patient with congenital dyserythropoietic anaemia (CDA) type III and two patients with severe congenital dyserythropoietic anaemia of an unusual type were reacted with mouse monoclonal antibodies against various globin chains and the reaction visualized using a gold-labelled goat antibody against mouse IgG. The multiple rounded intra-erythroblastic inclusions found in homozygous beta-thalassaemia reacted with the monoclonal antibody against alpha-globin chains but not beta-globin chains, thus confirming that they consisted of precipitated alpha-globin chains. The branching intra-erythroblastic inclusions found in HbH disease and CDA type III reacted with the monoclonal antibody against beta-globin chains but not alpha-globin chains, indicating that they consisted of precipitated beta-globin chains. The two patients with severe CDA had been transfusion-dependent since infancy, had a normal alpha:beta globin chain synthesis ratio or parents with normal red cell indices, displayed prominent dysplastic changes in their erythroblasts, and had intra-erythroblastic inclusions resembling those seen in homozygous beta-thalassaemia. However, unlike those in beta-thalassaemia, the inclusions in these two patients did not react with the monoclonal antibody against either alpha- or beta-globin chains. The inclusions reacted with antibody against zeta-globin chains, but detailed studies in one of the patients indicated that the antigen involved was not zeta-globin. These patients have features not reported in the condition known as dominantly inherited inclusion body beta-thalassaemia and appear to suffer from a novel type of CDA in which the intra-erythroblastic inclusions may consist of some non-globin protein or structurally-abnormal alpha-globin chains.

Anemia, Dyserythropoietic, Congenital↗
PubMed1996

Congenital dyserythropoiesis characterized by marked macrocytosis, vitamin B12- and folate-independent megaloblastic change and absence of the defining features of congenital dyserythropoietic anaemia types I or III.

Four patients with congenital dyserythropoiesis characterized by marked macrocytosis, little or no anaemia, and vitamin B12- and folate-independent megaloblastic erythropoiesis are reported. Their erythroblasts also showed various dysplastic changes but not those diagnostic for congenital dyserythropoietic anaemia (CDA) types I or III. The haematological features of the four patients, who included two siblings, resemble those of a previously reported patient and together these patients form a recognizable subgroup within those cases of CDA not belonging to CDA types I-III. In two of the cases studied, and possibly a third, the inheritance was as an autosomal recessive character.

Adult↗
PubMed1996

Differences in the serum levels of acetaldehyde and cytotoxic acetaldehyde-albumin complexes after the consumption of red and white wine: in vitro effects of flavonoids, vitamin E, and other dietary antioxidants on cytotoxic complexes.

After the consumption of ethanol, acetaldehyde levels increase in the serum, and the serum develops a nondialyzable cytotoxic activity caused by the formation of unstable acetaldehyde-albumin complexes. The concentration of acetaldehyde in the serum and the cytotoxic activity in serum albumin 8.5 hr after six healthy volunteers began to drink 94 g of ethanol were significantly less when the ethanol was consumed as red wine than as white wine. The serum acetaldehyde was measured by a fluorigenic HPLC assay, and the cytotoxic activity in albumin was determined using two different assays based on dissimilar endpoints: (1) detachment of adherent A9 cells and (2) impairment of the ability of A9 cells to reduce tetrazolium. When serum obtained from five other healthy volunteers after the consumption of white wine was incubated at 37 degrees C for 3 hr with a number of dietary antioxidants at a concentration of 100 mumol/liter, the cytotoxicity of the albumin was markedly reduced. The antioxidants studied consisted of six flavonoids (kaempherol, fisetin, quercetin catechin, taxifolin, and coumarin) and three nonflavonoids (salicylic acid, tannic acid, and alpha-tocopherol). In the cases of alpha-tocopherol, a statistically significant reduction of cytotoxicity was observed at a concentration of 10 mumol/liter. In addition, the cytotoxicity of artificially prepared acetaldehyde-albumin complexes was significantly reduced when such complexes were incubated with 50 to 100 mumol/liter of kaempherol, fisetin, quercetin, coumarin or salicylic acid, or 10 mumol/liter of alpha-tocopherol at 37 degrees C for 3 hr. Evidently, in vitro, flavonoid and nonflavonoid dietary constituents reduce the amount of unstable acetaldehyde-albumin complexes found in both postalcohol serum and in artificially produced acetaldehyde-albumin complexes. The difference in the amount of unstable acetaldehyde-albumin complexes found in serum after the consumption of red and white wine may therefore be caused by the higher concentration of antioxidants, including flavonoids, in red wine than in white wine. Because acetaldehyde and acetaldehyde-albumin complexes have been implicated in the pathogenesis of alcohol-mediated tissue damage, these data suggest that dietary antioxidants may influence the biological consequences of excess alcohol consumption.

Acetaldehyde↗
PubMed1996

Increased serum levels of macrophage colony-stimulating factor (M-CSF) in alpha- and beta-thalassaemia syndromes: correlation with anaemia and monocyte activation.

Serum levels of M-CSF were determined by an ELISA method in 29 and 34 patients with HbH disease (alpha 1/alpha 2 or alpha 2/HbCS) or beta zero-thal/HbE, respectively, in 28 haematologically normal subjects and in five patients with anaemia due to iron deficiency or myelodysplasia. In HbH disease and beta zero-thal/HbE, M-CSF concentrations were significantly higher than those in the normal subjects [986 +/- 138 and 1385 +/- 133, respectively, vs. 500 +/- 33 pg/ml (mean +/- SEM); p < 0.01, and p < 0.001, respectively]. By contrast, in patients with anaemia due to iron deficiency, M-CSF levels were within the normal range. In HbH disease and in beta zero-thal/HbE, M-CSF levels correlated inversely with mean basal Hb values (r = -0.39, p = 0.05 and r = -0.60, p < 0.001, respectively). In addition, in some of the HbH and beta zero-thal/HbE patients, monocyte ADCC activities towards red cells were tested and found to be approximately twice as high as those in normal controls [38.3 +/- 5.7 and 30.7 +/- 4.6 vs. 17.8 +/- 1.8% specific lysis (mean +/- SEM), respectively; p < 0.01 and p < 0.02, respectively]. When thalassaemic patients and normal controls were considered together there was a significant correlation between M-CSF levels and monocyte ADCC activities (r = 0.51, p < 0.02). The results suggest that in HbH disease and in beta zero-thal/HbE, raised serum M-CSF contributes to the anaemia by enhancing the effector function of mononuclear phagocytes towards red cells.

Adolescent↗
PubMed1996

Malignant lymphoma in congenital dyserythropoietic anaemia type III.

A 60 year old woman with congenital dyserythropoietic anaemia (CDA) type III developed a malignant T cell lymphoma with cutaneous and widespread nodal involvement. Bone marrow aspirates showed erythroid hyperplasia and dyserythropoiesis with multinucleate erythroblasts and gigantoblasts, in keeping with CDA type III. Electron microscopy showed multinucleate erythroblasts with notably irregular nuclear outlines and intranuclear clefts. The development of malignant lymphoma in this patient, together with a documented high prevalence of monoclonal gammopathy and multiple myeloma and a single case of Hodgkin's disease, may indicate an increased incidence of lymphoproliferative disease in CDA type III.

Anemia, Dyserythropoietic, Congenital↗
PubMed1996

Limited value of serum holo-transcobalamin II measurements in the differential diagnosis of macrocytosis.

AIM: To study the value of serum holo-transcobalamin II (holo-TCII) measurements in the differential diagnosis of macrocytosis. METHODS: Holo-TCII concentrations were measured in serum samples from 50 healthy non-vegetarian subjects and 30 patients with macrocytosis, using a technique based on the adsorption of holo-TCII with amorphous, precipitated silica. Deoxyuridine (dU) suppression tests were performed on the bone marrow cells of all the patients. Haematological diagnoses were made using standard criteria. RESULTS: The causes of macrocytosis were cobalamin (Cbl) deficiency due to pernicious anaemia or following partial gastrectomy (10 patients), dietary folate deficiency with/without Cb1 deficiency (four patients), chronic alcoholism (four patients), myelodysplastic syndrome (five patients), treatment with methotrexate or azathioprine (three patients), and congenital dyserythropoietic anaemia (CDA) (four patients). Undetectable or low holo-TCII concentrations were found in all patients with Cb1 deficiency and in some or all patients from each of the other diagnostic categories. There was also no correlation between the dU suppressed value and the holo-TCII concentration: all 15 patients with high dU suppressed values and nine of 15 with normal dU suppressed values, including four patients with CDA, had low holo-TCII concentrations. CONCLUSIONS: Measurements of serum holo-TCII concentrations by the silica adsorption method are not of value in the differential diagnosis of macrocytosis. The finding of low serum holo-TCII concentrations in patients with macrocytosis due to causes other than Cb1 deficiency may result not only from a state of negative Cb1 balance but also from other factors, such as increased utilisation of holo-TCII as a consequence of erythroid hyperplasia.

Biomarkers↗
PubMed1995

Morphology, biology and biochemistry of cobalamin- and folate-deficient bone marrow cells.

B12- or folate-deficient haemopoietic cells display abnormalities in their morphology under both the light and electron microscope, their cell kinetics and their capacity to synthesize protein. These abnormalities are maximal in the last dividing cell class and in non-dividing cells, presumably because B12 and folate uptake is largely confined to the most immature erythroid and granulocyte precursors. In patients with moderate or severe anaemia due to B12 or folate deficiency, erythropoiesis is markedly ineffective; intramedullary cell death occurs mainly in the early and late polychromatic megaloblasts. The damaged erythroblasts appear to display neoantigens or normally-hidden antigens at their cell surface and these react with naturally occurring antibodies. The opsonised erythroblasts are then recognised by macrophages via their IgG-Fc receptors and phagocytosed. Marrow cells from B12- or folate-deficient patients show a subnormal suppression of 3H-thymidine incorporation after pre-incubation with nonradioactive deoxyuridine, suggesting that such cells suffer from an impairment of the 5,10-methylene-THF-dependent methylation of deoxyuridylate to thymidylate. However, the exact mechanism by which B12 deficiency causes a reduced supply of this folate coenzyme is uncertain. Methylcobalamin is required for the 5-methyl-THF-dependent methylation of homocysteine to methionine and an impairment of this reaction will result in both reduced conversion of 5-methyl-THF to THF and in reduced methionine synthesis. There is controversy as to whether the reduced supply of THF or methionine is responsible for the reduced availability of 5,10-methylene-THF. Currently, the balance of evidence favours the hypothesis that the reduced supply of methionine leads to reduced synthesis of formyl-THF and, eventually, of 5,10-methylene-THF. Despite the evidence for impaired thymidylate synthesis, the duration of the S phase of megaloblasts appears to be normal or only modestly increased. Data on rates of DNA strand elongation are inconsistent, with subnormal rates reported in PHA-stimulated B12- or folate-deficient lymphocytes and normal rates in B12- or folate-deficient bone marrow cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Apoptosis↗
PubMed1995

Expression of an erythropoietin-like gene in the trout.

Cross-species Northern blot hybridization and radioimmunoassay have provided evidence for the expression of an erythropoietin (EPO)-like gene in the rainbow trout. The principal site of EPO-like mRNA and antigen expression in the adult trout appears to be the kidney which also acts as the major erythropoietic organ. The data suggest that a locally produced EPO-like factor may regulate renal erythropoiesis in bony fish and, furthermore, they identify a possible evolutionary origin for renal EPO production in mammals.

Animals↗
PubMed1995

The effect of Kupffer cell elimination on ethanol-induced liver damage in mice.

C57BL/10 mice develop inflammatory and necrotic changes in the liver, as well as raised serum ALT activities, after 9 days of exposure to ethanol vapour. If mice were injected twice with liposomes containing dichloromethylene diphosphonate (DMDP), with an interval of 5 days between the injections, there was complete elimination of Kupffer cells (hepatic macrophages) for a 9-day period starting 1 day after the first injection. The inflammatory and necrotic changes were significantly reduced in mice injected with liposomes containing DMDP as compared to uninjected mice or mice injected with empty liposomes; serum ALT activities were also significantly reduced. No significant difference was seen in serum tumour necrosis factor-alpha levels between the different groups. Kupffer cells therefore play a significant role in the development of the liver damage resulting from exposure to ethanol. Acetaldehyde production by Kupffer cells is one way in which these cells can damage hepatocytes and further work needs to be done to investigate this and other mechanisms.

Animals↗
PubMed1995

Ethnic differences in the biological consequences of alcohol abuse: a comparison between south Asian and European males.

Twenty-two South Asian men and 32 European men who had abused alcohol for at least 1.5 years were studied at the time of admission for detoxification to an Alcohol and Drug Dependency unit. The self-confessed average alcohol consumption during the preceding 3 months was similar in the South Asians (mean 383 g/day) and Europeans (mean 435 g/day) but the total duration of alcohol abuse was significantly shorter in South Asians (geometric mean 7.4 years) than Europeans (geometric mean 13.1 years). The geometric mean values for the concentration of carbohydrate-deficient transferrin in the serum were similar in the two ethnic groups. However, the red cell distribution width, the percentages of HbA1a+b, HbA1c and total HbA1 in red cell lysates and the activities of gamma-glutamyl transpeptidase, aspartate aminotransferase and alanine aminotransferase in the serum were all significantly higher in the South Asians than Europeans. The data suggest that South Asian men who abuse alcohol may be more susceptible to alcohol-related liver damage and acetaldehyde-mediated haemoglobin modification than European men who abuse alcohol to a similar extent for a considerably longer period.

Adult↗
PubMed1994

In vivo effects of vitamin C on the cytotoxicity of post-ethanol serum.

The consumption of alcohol is followed by the development in the serum of a non-dialysable cytotoxic activity against A9 cells. This cytotoxicity has been previously shown to reside mainly in unstable acetaldehyde-albumin complexes from which cytotoxic acetaldehyde molecules can be transferred to target cells. The cytotoxicity developing in serum albumin 8 hr after seven healthy volunteers drank 84 g ethanol over 45 min was abolished when the same volunteers were pre-treated with 1 g vitamin C daily for 3 days prior to alcohol consumption. The cytotoxicity was measured against A9 cells using two different indicators: (i) detachment of adherent cells and (ii) a decrease in the ability of cells to reduce tetrazolium. These data suggest that the administration of vitamin C may be useful in limiting those aspects of alcohol toxicity mediated by circulating acetaldehyde.

Alcohol Drinking↗
PubMed1994

Bone marrow cells from vitamin B12- and folate-deficient patients misincorporate uracil into DNA.

Bone marrow cells from 15 patients with normal deoxyuridine (dU) suppression test results, 3 healthy subjects, and 11 patients with megaloblastic anemia caused by vitamin B12 or folate deficiency were examined for misincorporation of uracil into DNA. Cells were incubated with [5-3H] uridine for 2 hours and their DNA extracted. The DNA was hydrolyzed to deoxyribonucleosides with DNase 1, phosphodiesterase and alkaline phosphatase, and any dU present was separated from other deoxyribonucleosides by Aminex A6 chromatography. The quantity of dU/mg DNA and the radioactivity in the dU peak/mg DNA were then calculated. The results clearly showed that there was markedly increased uracil misincorporation into the DNA of vitamin B12- or folate-deficient marrow cells. Misincorporation of uracil into DNA may be an important biochemical lesion underlying both the megaloblastic change and the ineffectiveness of hematopoiesis in vitamin B12 and folate deficiency.

Adult↗
PubMed1994

A novel form of congenital dyserythropoietic anemia associated with deficiency of erythroid CD44 and a unique blood group phenotype [In(a-b-), Co(a-b-)].

We have used a panel of well-characterized monoclonal antibodies (MoAbs) to examine the blood cells of a patient with a novel form of congenital dyserythropoietic anemia (CDA) characterized by intra-erythroblastic and intra-erythrocytic membranous inclusions. Twelve antibodies defining three nonoverlapping epitope groups on the extracellular domain of CD44 all failed to react with the red blood cells (RBCs) of the patient. A rabbit antibody to the cytoplasmic domain of CD44 from normal RBCs failed to react with the patient's RBC ghosts. In contrast, the patient's lymphocytes, granulocytes, and monocytes showed apparently normal CD44 expression. Bone marrow preparations stained with CD44 antibodies and visualized with 125I antimouse Ig (F(ab')2) followed by autoradiography showed positive staining of lymphocytes and myeloid cells but not of most orthotolidine-positive erythroblasts. The patient's RBCs also gave weaker than normal reactions with MoAbs of anti-LWab specificity while MoAbs to glycophorins A, B, and C, Rh polypeptides, CD47, CD55, CD58, CD59, acetylcholinesterase, and Lutheran and Kell glycoproteins all gave normal reactions. Agglutination tests with human blood grouping sera demonstrated that the RBCs of the patient have the unique phenotype In(a-b-), Co(a-b-) and that they also lack the high incidence RBC antigen AnWj. The phenotype In(a-b-) would be expected because these antigens are known to be expressed on CD44. There is also some evidence associating the AnWj antigen with CD44. However, the CO blood group locus is on chromosome 7p whereas that for CD44 is on chromosome 11p. Quantitative binding assays using 125I-labeled Fab fragments of CD44 antibodies did not show any evidence for reduced levels of CD44 on RBCs from the parents of the patient or from her unaffected sister. The parents and sister had the common Colton blood group phenotype [Co(a+b-)]. Neither deficiency of CD44 nor absence of Colton antigens are general features of CDA because erythrocytes from patients with CDA I, CDA II, CDA III, and two other unclassified CDAs had normal expression of CD44 and normal Colton blood group phenotypes. Further analysis of the defect(s) present in the patient's erythroid cells may provide useful information regarding membrane assembly and the regulation of differentiation in normal erythroid cells.

Anemia, Dyserythropoietic, Congenital↗
PubMed1994

Macrophages are a major source of acetaldehyde in circulating acetaldehyde-albumin complexes formed after exposure of mice to ethanol.

C57BL mice were depleted of macrophages by an intravenous injection of liposome-encapsulated dichloromethylene diphosphonate (DCMDP), and control mice were uninjected or injected with empty liposomes. One day after injection, a proportion of the DCMDP-treated and control mice was continuously exposed to ethanol vapor for 4 days. Albumin fractions were separated from the sera of both ethanol-unexposed and ethanol-exposed animals and tested for cytotoxicity against a monolayer of A9 cells using two indicators of cytotoxicity: detachment of adherent cells and a decrease in the ability of cells to reduce tetrazolium. The results show that, in mice exposed to ethanol, macrophages are a major source of the acetaldehyde in circulating cytotoxic acetaldehyde-albumin complexes and presumably also of free acetaldehyde.

Acetaldehyde↗
PubMed1994

Intravascular haemolysis and increased prevalence of myeloma and monoclonal gammopathy in congenital dyserythropoietic anaemia, type III.

A family with congenital dyserythropoietic anaemia type III was studied. Twenty patients and 10 of their healthy siblings were clinically examined and questioned about their medical history. Blood sampling and bone marrow aspirations were also performed. Forty-five percent of the patients reported symptoms of anaemia and 35% regularly felt weakness, fatigue, or headache. However, the majority of the patients regarded themselves as healthy. The bone marrow showed a uniform picture of erythroid hyperplasia with multinuclear erythroblasts and gigantoblasts with up to 12 nuclei. There was laboratory evidence of intravascular haemolysis and mild anaemia. We also observed a high prevalence of monoclonal gammopathy of undetermined significance (3 cases) and myeloma (1 case) among the patients.

Anemia, Dyserythropoietic, Congenital↗
PubMed1994

Correlations between acetaldehyde-modified haemoglobin, carbohydrate-deficient transferrin (CDT) and haematological abnormalities in chronic alcoholism.

Serum levels of carbohydrate-deficient transferrin (CDT), the proportions of eight haemoglobin fractions separated by cation exchange liquid chromatography, indices of liver function and various haematological parameters were determined in most of a group of 49 chronic alcoholics who had misused alcohol for at least the preceding 3 months and in 15 healthy non-alcoholic control subjects. The percentages of alcoholics giving abnormally high values for gamma-glutamyl transferase (GGT) activity, CDT levels, GGT activity or CDT levels or both, and aspartate aminotransferase (AST) activity were, respectively, 73.0, 71.0, 87.1 and 64.4. The percentages of patients giving abnormally high values for the proportion of HbA1a, proportion of HbA1ach, proportion of HbA1a or HbA1ach or both, MCH, MCV and red cell distribution width (RDW) were, respectively, 46.8, 25.5, 55.3, 55.3, 36.2 and 29.8. Reduced values for the red cell folate concentration, lymphocyte count and platelet count were found in 36.2%, 6.4% and 17.0%, respectively, of the alcoholics. When compared with the control subjects, the group of alcoholics showed statistically significant increases in the mean values for the MCV, MCH, MCHC and RDW and statistically significant decreases in the mean values for the haemoglobin distribution width (HDW) and the logarithms of the holo-transcobalamin II concentrations and the platelet count. The logarithms of the CDT values correlated directly with the MCV and MCH and inversely with the logarithms of the lymphocyte or platelet counts and the HDW, suggesting but not proving that the haematological changes in chronic alcoholism may be at least partly related to defective glycosylation of the constituents of developing blood cells or, possibly, of haemopoietic growth factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetaldehyde↗