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L Verstraeten

Publications and source records attributed to L Verstraeten.

At least 19 recordsLinked to original sources
PubMed2001

Highly heterogeneous nature of delta-aminolevulinate dehydratase (ALAD) deficiencies in ALAD porphyria.

The properties of 9 delta-aminolevulinate dehydratase (ALAD) mutants from patients with ALAD porphyria (ADP) were examined by bacterial expression of their complementary DNAs and by enzymologic and immunologic assays. ALADs were expressed as glutathione-S-transferase (GST) fusion proteins in Escherichia coli and purified by glutathione-affinity column chromatography. The GST-ALAD fusion proteins were recognized by anti-ALAD antibodies and were enzymatically active as ALAD. The enzymatic activities of 3 ALAD mutants, K59N, A274T, and V153M, were 69.9%, 19.3%, and 41.0% of that of the wild-type ALAD, respectively, whereas 6 mutants, G133R, K59N/G133R, F12L, R240W, V275M, and delTC, showed little activity (< 8%). These variations generally reflect the phenotype of ALAD in vivo in patients with ADP and indicate that GST-ALAD fusion protein is indeed useful for predicting of the phenotype of ALAD mutants. The location of F12L mutation in the enzyme's molecular structure indicates that its disturbance of the quaternary contact of the ALAD dimer appears to have a significant influence on the enzymatic activity. Mouse monoclonal antibodies to human ALAD were developed that specifically recognized a carboxy terminal portion of ALAD, or other regions in the enzyme. This study represents the first complete analysis of 9 mutants of ALAD identified in ADP and indicates the highly heterogeneous nature of mutations in this disorder.

Adolescent↗
PubMed2000

Molecular analysis of delta-aminolevulinate dehydratase deficiency in a patient with an unusual late-onset porphyria.

Cloning, expression, and genotype studies of the defective gene for delta-aminolevulinate dehydratase (ALAD) in a patient with an unusual late onset of ALAD deficiency porphyria (ADP) were carried out. This patient was unique in that he developed the inherited disease, together with polycythemia, at the age of 63. ALAD activity in erythrocytes of the patient was less than 1% of the normal control level. ALAD complementary DNA (cDNA) isolated from the patient's Epstein-Barr virus (EBV)-transformed lymphoblastoid cells had 2 base transitions in the same allele, G(177) to C and G(397) to A, resulting in amino acid substitutions K59N and G133R, respectively. It has been verified that the patient had no other ALAD mutations in this and in the other allele. By restriction fragment length polymorphism (RFLP) analysis, all family members of the proband who had one-half ALAD activity compared with the ALAD activity of the healthy control were shown to have the same set of base transitions. Expression of ALAD cDNA in CHO cells revealed that K59N cDNA produced a protein with normal ALAD activity, while G133R and K59N/G133R cDNA produced proteins with 8% and 16% ALAD activity, respectively, compared with that expressed by the wild type cDNA. These findings indicate that while the proband was heterozygous for ALAD deficiency, the G(397) to A transition resulting in the G133R substitution is responsible for ADP, and the clinical porphyria developed presumably due to an expansion of the polycythemic clone in erythrocytes that carried the mutant alad allele.

Age of Onset↗
PubMed2000

Screening for total and partial eosinoperoxidase deficiency by flow cytometry: prevalence in a general population, pathology and genetic implications.

The ADVIA (Bayer) haematological system differentiates leukocytes by their volume and their peroxidase (MPO and EPO) activity. It thus allows specific counting of the eosinophils and detection of totally EPO and MPO deficient individuals. EPO activity is determined by the coordinates of the eosinophil cluster on the outprint. A reliable method of quantitation by simple angle measure is suggested. It allows recognition of partial deficiencies. Among approximately 100,000 persons, 29 cases of total EPO deficiency were detected. No typical or specific pathology of the defect was noted. Family studies showed heterozygous parents and offspring to be partially deficient. The frequency of these partial deficiencies in the general population is studied. The results exclude a simple autosomal recessive monogenic transmission of the defect. A model for bigenic transmission is suggested.

Eosinophil Peroxidase↗
PubMed1993

[Parasitological evaluation of the stool].

The parasitologic investigation performed without clinical orientation in a routine laboratory allowed to identify the most common parasites, often cysts of protozoa, using a minimal technique. A more accurate investigation (e.g.: concentration, extraction and flotation) was hampered by a too large number of systematic specimens. The use of an immersion objective improves the detection and identification of cysts of protozoa. There is still some controversy on the virulence of small amoebae, flagellates, Blastocysts and Entamoeba coli, the infection being often massive. AIDS should predispose to new parasitic diseases such as cryptosporidiosis and strongyloidosis. A careful examination of stools for parasites has become mandatory in view of the wide geographical origin of patients with a parasitic disease.

Animals↗
PubMed1993

Biochemical diagnosis of a fatal case of Günther's disease in a newborn with hydrops foetalis.

The birth of a male baby was induced at 32 weeks. In utero, the child presented, inter alia, signs of hydrops, hepatosplenomegaly and anaemia. Two in utero transfusions for correction of the anaemia were performed at 28 and 29 weeks, respectively. The baby rapidly presented respiratory distress with mixed acidosis. Three hours after birth, pink urine was excreted. Signs of icterus necessitated phototherapy, after which photosensitivity occurred. Erythrocytes were fluorescent under long-wavelength UV light. The baby died 24 hours after birth, displaying severe acidosis, a diffuse haemorrhagic syndrome, and repeated brady-cardia which did not respond to isoprenaline. The analysis of porphyrins in urine, blood and faeces of the baby gave the following results: 1) uroporphyrin (I and III isomeric series) was increased in urine and faeces, with traces in erythrocytes and plasma; 2) heptacarboxyporphyrin I was found mainly in urine and much less in erythrocytes, plasma and faeces; 3) coproporphyrin I was increased in urine, erythrocytes, plasma and faeces, and 4) 5-aminolaevulinic acid and porphobilinogen in urine and plasma were within the reference ranges. Determination of the enzymes of haem biosynthesis in erythrocytes and lymphocytes showed that both parents possessed only 50% of the normal activity of cosynthase. A previously described point mutation in codon 73 was observed in one parent. Fatal cases of neonatal Günther's disease are extremely rare and such an observation, according to our knowledge, is probably one of the first described.

Aminolevulinic Acid↗
PubMed1991

[Association of idiopathic hemochromatosis and tardive cutaneous porphyria].

Porphyria cutanea tarda is a disorder of porphyrin metabolism that results from a deficiency of uroporphyrinogen decarboxylase, resulting in a characteristic pattern of porphyrin excretion. Elevated serum iron values are frequently observed among patients with porphyria cutanea tarda. The hypothesis has been advanced that a hemochromatosis allele is implicated in the clinical manifestation of porphyria cutanea tarda. We report the case of a patient suffering from both idiopathic hemochromatosis and porphyria cutanea tarda. The data of the medical literature concerning such an association are discussed.

Female↗
PubMed1991

Hereditary hepatic porphyria due to homozygous delta-aminolevulinic acid dehydratase deficiency: studies in lymphocytes and erythrocytes.

Activities of delta-aminolevulinic acid (ALA) dehydratase and porphobilinogen (PBG) deaminase, and haem content were determined in EB-virus transformed lymphocytes from two patients with homozygous ALA dehydratase deficiency, and their family members to determine the expression of the specific gene defect in this cell type. ALA dehydratase activity, but not PBG deaminase activity or haem content, was markedly decreased in lymphocyte preparations from both patients with homozygous enzyme deficiency, and moderately decreased in subjects heterozygous for enzyme deficiency. Immunochemical quantitation of erythrocyte ALA dehydratase suggested the presence of a cross-reactive material in a patient with a late-onset of acute hepatic porphyria due to the homozygous enzyme deficiency.

Adult↗
PubMed1991

Liquid preservation of polymorphonuclear leukocytes: effect of various additives on chemotaxis preservation.

Adequate storage of polymorphonuclear leukocytes would allow an easier in vitro study of their structure and their functions, an easier study of polymorphonuclear leukocyte diseases (e.g. chronic granulomatous disease) and an easier use of polymorphonuclear leukocytes as a clinical tool (e.g. for localizing infections). Unfortunately, polymorphonuclear leukocytes are nearly impossible to preserve, even in short-term storage. This study proposes a model for the study of polymorphonuclear leukocyte storage in a synthetic medium: Plasmion. For storage over a period of 24 h, we found that supplementation with each of the following additives: bicarbonate buffer, glucose, adenosine triphosphate (ATP), ascorbic acid, nicotinamide adenine dinucleotide (NADH), nicotinamide adenine dinucleotide phosphate (NADPH), alpha-tocopherol acetate, amikacin and ampicillin, significantly improves (p less than 0.05) one or several functions of the polymorphonuclear leukocytes. When samples were stored for 48 h, we found that the addition of bicarbonate buffer after 24 h significantly improves the maintenance of several functions of polymorphonuclear leukocytes, in particular chemotaxis. Preservation for 96 h was achieved by making additions of supplements on each day of storage, with a chemotaxis maintenance of 83% at 24 h, 59% at 48 h, 46% at 24 h and 20% at 96 h. In conclusion, by using the Plasmion medium, and adding the above-mentioned compounds on each day of storage, chemotaxis can be satisfactorily maintained over 4 days.

Blood Preservation↗
PubMed1991

[Experimental study of a model for granulocyte storage].

An efficient granulocytes preservation would allow an easier study of their structure and functions, of granulocytes functional diseases (e.g. chronic granulomatous disease) and an easier use of granulocytes as a clinical tool (e.g. for localizing infections or for transfusions). Unfortunately, granulocytes are nearly impossible to preserve, even in a short-term storage (less than 24 hours). This study proposes an experimental model which could improve in vitro granulocyte functions maintenance. Bicarbonate buffer, glucose, adenosine triphosphate, vitamins C and E, nicotinamide adenine dinucleotide, nicotinamide adenine dinucleotide phosphate, amikacin, and ampicillin supplementation significantly (p 0.05) improve maintenance of one or several granulocyte functions during storage.

Chemotaxis, Leukocyte↗
PubMed1991

[Storage of granulocytes].

Granulocytes transfusions set numerous problems and are less and less used. The very short maintenance of the granulocyte functions (chemotaxis) limits their use are a clinical tool (e.g. for localizing infections and for transfusions). Neither granulocyte collection by centrifugation methods (continuous or discontinuous flow) nor glucocorticoid premedication significantly alter granulocytes functions (in particular chemotaxis). Liquid preservation methods give better results than cryogenic methods. Optimal storage parameters are a temperature of 22 degrees C and a pH level close to 7.4. Chemotaxis is the most sensitive indicator of granulocyte damages in connection with storage. Bicarbonate buffer, glucose, proteins and reducing agents supplementation significantly improve chemotaxis maintenance. Cryogenic methods are less studied and less used. They allow storage of only little amounts of granulocytes. In conclusion, efficient granulocyte storage (over several days) would allow an easier use of these cells in many fields, but unfortunately, no solution is yet available.

Chemotaxis, Leukocyte↗
PubMed1990

Porphyric neuropathy and hereditary delta-aminolevulinic acid dehydratase deficiency in an adult.

A man without a history of porphyric attacks developed a subacute motor neuropathy at the age of 63. At the same time the first signs of a myeloproliferative disorder were found. He had a homozygous deficiency of erythrocyte delta-aminolevulinic acid dehydratase (ALA-D) with autosomal recessive inheritance. Treatment with parenteral glucose and with hematin had a beneficial influence on the plasma ALA levels. The finding of a motor neuropathy with increased plasma levels of ALA but not of porphobilinogen (PBG) supports the potential role of ALA in the pathogenesis of porphyric neuropathy.

Genetic Diseases, Inborn↗
PubMed1989

Biochemical diagnosis of an hereditary aminolaevulinate dehydratase deficiency in a 63-year-old man.

Porphyrin metabolism was investigated in a 63-year-old male patient who developed a subacute onset polyneuropathy with predominance of motor signs in the upper limb. The screening for lead, cadmium, mercury, aluminum and thallium was negative. The study of porphyrin metabolism showed remarkable abnormalities, particularly a very high level of plasmatic 5-aminolaevulinic acid contrasting with a normal level of porphobilinogen and a nearly complete loss of activity of aminolaevulinic acid dehydratase with no regenerative response to dithiothreitol or zinc ions. The other causes of aminolaevulinic acid dehydratase deficiency (tyrosinaemia, alcoholism, smoking, cirrhosis, renal insufficiency, diabetes mellitus) were ruled out. The diagnosis of primary aminolaevulinic acid dehydratase deficiency was proposed and confirmed by the familial study, which revealed the existence of several heterozygous members in this family.

Aluminum↗
PubMedDate not supplied

[Platelet antiaggregants].

Antiplatelet agents are indicated in the prophylactic treatment of certain thromboses, and in particular those due to a complication of atherosclerosis. Acetylsalicylic acid is the best-known, the most commonly used and, probably, the currently most effective agent. The dosage remains controversial; yet, a mean dose of 300 mg daily appears to be recommended nowadays. Ticlopidine and, to a lesser extent, dipyridamole can also be used for this treatment. However numerous contra-indications, such as haemorragic diathesis, surgery and gastric ulcers tend to limit their use. As regards the combination of antiplatelet agents, clinical studies do not show superior efficacy as compared with acetylsalicyclic acid alone.

Animals↗
PubMedDate not supplied

[The physiology of primary hemostasis].

Primary haemostasis, on the same grounds as coagulation and fibrinolysis, is one of the three main stages of haemostasis. It involves mainly the vascular endothelium and the blood platelets. An endothelial lesion will uncover thrombogenic structures-mainly microfibrils and collagen-to which the platelets will adhere. The latter will then undergo a complete morphological transformation, from a discoid shape to a structure provided with pseudopods. This transformation is accompanied by a biological explosion, which affects in the first place the metabolism of prostaglandins and of cyclic AMP. There occurs also a release of the contents of the platelet granules. The final phase of platelet activation consists in their aggregation, which is reversible in a first time and irreversible afterwards. On the other hand, the activated platelets can also trigger the process of coagulation, which demonstrates the narrow relationship between the various stages of haemostasis.

Animals↗
PubMedDate not supplied

[The physiology of hemostasis: plasma and tissue factors in coagulation and fibrinolysis].

Coagulation and fibrinolysis are two antagonistic phenomena, the harmonious balance of which results form a perfect regulation of their respective activators and inhibitors. Indeed, the efficacy of the response of the organism to an aggression against the blood vessel and its plasmatic and cellular contents, depends on the capacity of maintaining this balance. The mechanisms involve plasma proteins (factors) endowed with a proteolytic activity, as well as mediators released from injured tissues (endothelium). Coagulation corresponds to the process of fibrin formation (fibrin clump), which assures the consolidation of the platelet clot which was pre-formed during the activation of the platelets. Fibrinolysis consists in the gradual dissolution of this fibrin clump, aimed at re-permeabilization of the vessel at the site of the lesion, and thus at a normalization of the blood circulation at this level. Coagulation and fibrinolysis can hardly be dissociated from primary haemostasis (platelet activation), not only because of their interactions, but also because of their chronology: all these events are, indeed, triggered almost simultaneously, even though the duration varies. The mechanisms that are implicated in thrombo-embolic phenomena are comparable to those of physiological haemostasis. However, it is the imbalance between these events which constitutes the pathological aberration and thus induces the formation of a fibrin-platelet thrombus.

Blood Coagulation↗