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Storage pool disease in chronic lymphocytic leukemia: abnormal aggregation and secretion without bleeding.

Although bleeding complications are relatively common in patients with chronic lymphocytic leukemia, they tend to be related to thrombocytopenia or an acquired clotting factor inhibitor. Chronic lymphocytic leukemia-associated thrombocytopenia, which may also contribute to the hemorrhagic risk, is generally caused by decreased production and immune-mediated destruction. This is the case of a 56-year-old man with longstanding chronic lymphocytic leukemia who developed thrombocytopenia (platelet counts of approximately 50,000/microL) with an associated abnormal platelet morphology. Although the patient did not suffer clinically significant bleeding, several tests of platelet function were grossly abnormal. Electron microscopic examination of the platelets revealed virtually complete absence of dense granules. Platelet aggregation did not occur with adenosine diphosphate (10 microM), collagen (2 micrograms/mL), or ristocetin (1 mg/mL). Doubling the agonist concentrations produced only minimal agglutination with ristocetin. The bleeding time was mildly prolonged at 9.0 and 10.5 minutes. Von Willebrand antigen and ristocetin cofactor levels were normal. Collagen-induced adenosine triphosphate secretion was less than 10% that of a matched normal control. In contrast, platelet force development was virtually normal, reaching 4,800 dynes at 1,200 seconds compared with 5,800 dynes for the healthy control. The patient's clots demonstrated enhanced clot modulus 44,000 dynes/cm2 versus 22,400 dynes/cm2 for the healthy control. The latter finding was primarily because of high fibrinogen concentration. This third report of storage pool disease in a patient with chronic lymphocytic leukemia demonstrates that dense granule release is not required for normal platelet-mediated force development.

Adenosine Triphosphate↗

Pseudo-storage pool disease due to platelet degranulation in EDTA-collected peripheral blood: a rare artifact.

We report a patient who was referred for acute myocardial infarction and presented a pseudo-storage pool disease. The platelets from the blood collected with ethylene diamine tetra-acetic acid (EDTA) were moderately underestimated by the automated analyser, stained poorly on the blood smear and appeared agranular under the microscope. This artifactual anomaly does not occur in samples anticoagulated with citrate, heparin or the mixture citrate theophyline adenine dipyridamole. Reports of EDTA-induced pseudo-storage pool disease are scarce, possibly because underestimation of this poorly explained and difficult to diagnose phenomenon.

Aged↗

A girl with Hermansky-Pudlak syndrome.

A young girl with ocular albinism and the Hermansky-Pudlak syndrome is described. Ocular albinism generally occurs in males. In this condition, the pigmentation of the skin and hair is nearly normal, and the melanin pigment abnormality is limited to the eyeballs. The chief complaints are visual disturbance, nystagmus, and photophobia. A 3-year-old girl was recently brought to our hospital with nystagmus, which she had exhibited since the age of 1 year. Funduscopy resulted in a diagnosis of ocular albinism. Further investigations, specifically, microscopy of her platelets, led us to conclude that she had Hermansky-Pudlak syndrome.

Albinism, Oculocutaneous↗

The Hermansky-Pudlak syndrome. Variable reaction to 1-desamino-8D-arginine vasopressin for correction of the bleeding time.

The effect of the synthetic vasopressin derivative 1-desamino-8D-arginine vasopressin (DDAVP = Minrin) on bleeding time was studied in nine patients with Hermansky-Pudlak syndrome; four of them were Dutch, five were Belgian. Shortening of bleeding time was observed in four of the patients with this type of storage pool disease; in one patient the response was equivocal, in two patients the response was not dramatic and in two there was no response at all. DDAVP may be useful in managing the bleeding disorder in some patients with Hermansky-Pudlak syndrome. Therefore, every patient with this syndrome should be tested with DDAVP as a preventive measure.

Adolescent↗

[Fawn-Hooded Rat; an animal model of development of pulmonary hypertension].

The Fawn-Hooded Rat (FHR) spontaneously develops pulmonary hypertension (PH) at sea level, and an increased severity of this disease is observed upon exposure to mild hypoxia. A recent report suggested that lung hypoplasia with decreased alveolarization and altered vascular growth led by the decreased activity of endothelial nitric oxide synthase may contribute to the development of PH in the FHR. Exposure to mild hypoxia (P1O2 = 120 mmHg) leads to severe PH in FHR but not in Tester Moriyama rat, a strain that has a serotonin platelet storage-pool deficiency (PSPD) similar to that of the FHR. A serotonin PSPD does not appear to predispose FHR to PH. Endothelin-1 (ET-1) mRNA and peptide levels are increased in the hypertensive lungs of mildly hypoxic FHR. ET-1 may at least partly contribute to the development of PH in this strain.

Animals↗

Genetic mapping and characterization of the bleeding disorder in the fawn-hooded hypertensive rat.

Release of platelet dense granule contents occurs in response to vascular injury, playing an important role in platelet aggregation and primary hemostasis. Abnormalities of the platelet dense granules results in a bleeding disorder of variable severity termed "storage pool defect" (SPD). We have examined the fawn-hooded hypertensive (FHH) rat as a model of SPD in order to genetically map the locus (Bd) responsible for prolonged bleeding. Platelet function assays of the FHH rat confirmed the presence of a platelet dense granule SPD. However electron microscopy and lysosomal enzyme assays indicated differences between the FHH rat and other rodent models of SPD. Genetic mapping through the use of congenic FHH rats localized the Bd locus to an approximately 1 cM region on rat chromosome 1. Through the use of comparative mapping between species and analysis of the initial draft of the rat genome assembly, six known and thirty-four putative genes were identified in the Bd locus. None of these genes have been previously implicated in platelet function. Therefore positional cloning of the gene responsible for the bleeding disorder in the FHH rat will lead to new insights in platelet physiology, with implications for diagnosis and management of hemostatic and thrombotic disorders.

Animals↗

Assessment of lumiaggregometry for research and clinical laboratories.

Platelet aggregometry is often used to help diagnose storage pool disease (SPD-reduced amounts of granule nucleotides) and release defects (abnormal release of granule nucleotides). The general assumption that normal aggregation patterns are sufficient to rule out the diagnosis of one of these disorders has been invalidated by the recent publication of two papers describing patients with clinical bleeding, prolonged bleeding times and normal aggregation patterns in spite of defective release. The lumiaggregometer provides a tool for measuring platelet release and aggregation simultaneously. This paper presents a standardized, reproducible method for the use of the lumiaggregometer based on a "standard curve". Data obtained during the development of the procedure are presented including normal ranges of release at different concentrations of agonists, release measured in intrinsic disorders as well as in patients on aspirin, and values for release relative to varying platelet counts. A monoclonal antibody (anti-p24/CD9; MAb7) which activates platelets similarly to thrombin and may be a useful reagent for distinguishing SPD and release defects is also introduced.

Adenosine Triphosphate↗

Characterization of a thrombopathy (type delta storage pool disease) affecting a pig colony.

An autosomal recessive thrombopathy in pigs is described and characterized functionally, morphologically and biochemically. The affected pigs have a severe bleeding diathesis and a markedly prolonged bleeding time but normal plasma and platelet von Willebrand factor (vWF) levels. Electron micrographs and fluorescence microscopy with mepacrine reveal reduced numbers of dense granules in platelets as compared to normals. This thrombopathy is a pure delta storage pool disease (SPD), as evidenced: a) biochemically by platelet serotonin content and metabolism and by comparative ATP/ADP content and secretion; b) functionally by reduced aggregability to low concentrations of convulxin and collagen but normal aggregability to other agents and normal synthesis of thromboxane B2. The affection was first discovered in a colony of von Willebrand's disease (vWD) pigs, but is biologically and genetically distinct. It is possible to completely separate the SPD from the vWD, although originally animals could be affected by both vWD and SPD. Normal plasma and platelet alpha granule content of vWF are found in diseased animals. An intermediate disorder is also detected in animals not severely affected, which may represent the heterozygous state.

Acetylserotonin O-Methyltransferase↗

Characterization of platelet function in cyclic hematopoietic dogs.

Platelet aggregation to incremental doses of eight different platelet agonists (collagen, thrombin, platelet-activating factor [PAF], arachidonic acid [AA] plus epinephrine, the calcium ionophore A23187, ADP, phospholipase C [PLC], and 12-O-tetradecanoyl phorbol-13-acetate [TPA]) was compared in normal (N) and cyclic hematopoietic (CH) dogs. Platelet aggregation was defective with collagen, PAF, TPA, and possibly thrombin as agonists but normal when ADP, PLC, arachidonic acid plus epinephrine, and A23187 were used as agonists with CH platelets. In heterozygous CH dogs, platelet aggregation was intermediately defective when tested with collagen and PAF as agonists. Thromboxane B2 (TXB2) concentrations (mean +/- SD; pg/10(6) platelets), as measured by RIA, were similar in CH and normal dogs both prior to (CH: 7.6 +/- 7.0; N: 5.5 +/- 3.9) and after collagen stimulation (collagen: 141.3 +/- 42.5; 123.1 +/- 38.4). Granule storage pools of serotonin and platelet adenine nucleotides were markedly decreased in homozygous CH but not heterozygous CH dogs. Thrombin stimulated phosphorylation of 40- and 20-kd proteins in platelets from CH and normal dogs to an equal extent. However, collagen-stimulated phosphorylation of the 40- but not the 20-kd protein was significantly decreased in platelets from CH dogs. These data suggest that there is a biochemical defect in platelets from CH dogs that results in storage pool disease and decreased phosphorylation of a 40-kd protein.

Animals↗

Studies on platelet protein phosphorylation in patients with impaired responses to platelet agonists.

The phosphorylation responses of platelet proteins after platelet stimulation with agonists were studied in patients with clinical bleeding disorders and various types of impaired platelet functional responses. Impaired collagen-induced phosphorylation, particularly of the 47 kd substrate (P47) for protein kinase C, was observed in one patient whose platelet defect appears to be an impaired initial response to weak platelet agonists but whose platelet secretory mechanism is normal. Reduced phosphorylation of a 31 kd polypeptide was also observed. The phosphorylation defect in this patient differs from that seen in another patient in whom impaired P47 and myosin light chain phosphorylation was observed but whose functional defect may be more closely related to secretion. The results provide further evidence that phosphorylation of P47 may play a role in platelet activation mechanisms preceding secretion and that abnormalities of phosphorylation of both P47 and myosin light chain may be associated with platelet functional defects in some patients with bleeding disorders.

Adenosine Diphosphate↗

[Megaloblastic anemia and platelet function--a qualitative platelet defect in pernicious anemia].

In order to know the entities of platelet defect in pernicious anemia, we investigated platelet functions in ten cases with pernicious anemia. Three of the cases had total gastrectomy. Five cases showed thrombocytopenia and four cases revealed prolongation of Ivy bleeding time. Decreased adhesiveness was observed in three cases. Various abnormalities in platelet aggregation were observed. However, almost all of the cases showed remarkable improvement of decreased platelet functions after the therapy of Vitamin B12 injection. The results of adenine nucleotides in platelets and the release of them following collagen or epinephrine aggregation were analysed in comparison with normal platelets. The ADP was definitely decreased and the ATP/ADP ratio was increased. In addition, the release of ATP and ADP at collagen or epinephrine induced aggregation was markedly decreased, and after the therapy of Vitamin B12, the decrease of adenine nucleotide release remarkably increased. In summary, the acquired defects of platelet function in pernicious anemia are regarded as a secondary storage pool disease, and its defects improve after Vitamin B12 therapy.

Adult↗

[Examination of platelet aggregation and ultrastructure in patients with non-Hodgkin's lymphoma].

Aggregation and secretion reaction of thrombocytes were studied in 54 patients suffering from Non-Hodgkin's++Lymphoma. Results were compared with electron-microscopic findings on thrombocytes of the same patients. Slight changes were found in stage II. In stage IV distinct therapy-resistant changes were noted in combination with storage pool disease syndrome which is to be considered as a consequence of impaired generation of thrombocytes in bone marrow.

Antineoplastic Combined Chemotherapy Protocols↗

[Hermansky-Pudlak syndrome].

Hermansky-Pudlak syndrome is a hereditary disease with an autosomal recessive mode of inheritance, characterized by the triad of tyrosinase-positive oculocutaneous albinism, a hemorrhagic diathesis resulting from storage pool-deficient platelets, and accumulation of ceroid/lipofuscin-like material in various cells and tissues and in the urine. The basic defect in this syndrome remains unknown. It is believed that the primary defect may involve membranes of the platelet-dense bodies and the melanosomes. Recently a defective calcium uptake system and low activities for membrane-associated thioredoxin reductase have been shown in Hermansky-Pudlak syndrome, and their possible role in the pathomechanism of this disorder is discussed.

Albinism↗