Drug-induced thrombocytopenia is associated with increased binding of IgG to platelets both in vivo and in vitro

Thrombocytopenia is a common serious adverse effect of drug treatment. A variety of in vitro diagnostic techniques to confirm the diagnosis are available, but the majority lack sufficient sensitivity to detect all cases of drug-induced thrombocytopenia. We studied 19 patients with suspected drug-induced thrombocytopenia and demonstrated that platelet- associated IgG (PAIgG) was elevated in all at the time of thrombocytopenia, and PAIgG returned to normal levels as the thrombocytopenia resolved. In the majority of patients, the platelet count rapidly returned to normal after the drug was discontinued; however, in six patients, the thrombocytopenia persisted well beyond the period of time that the offending drug would be expected to be cleared from the blood. In 13 patients, serum obtained after recovery was used to identify the drug responsible for the thrombocytopenia in an in vitro assay. In all cases, the addition of the drug historically associated with the thrombocytopenic episode was associated with an increased binding of IgG to control platelets. For uncertain reasons, the concentration of drug required to increase the in vitro binding of IgG to test platelets was often more than the concentration usually achieved in vivo. Wider application of these techniques may provide better understanding of the clinical characteristics and mechanisms responsible for drug-induce thrombocytopenia.     

A canine model of hemophilic (factor VIII:C deficiency) bleeding

A model of bleeding due to clotting factor deficiency has been developed in dogs. Normal and hemophilic (factor VIII:C deficient) animals were used. Bleeding was induced in lightly anesthetized animals by severing the apex of the nail cuticle using a guillotine device. In normal animals, bleeding usually ceased spontaneously after 2-8 min. In contrast, in hemophilic animals, bleeding continued for up to 20 min and necessitated either cauterization or the application of topical thrombin to achieve hemostasis. Pretreatment of the hemophilic animals with canine cryoprecipitate corrected the cuticle bleeding time to within the range noted for normal animals. The method is simple and reproducible and has the advantage that a number of observations can be made sequentially on the same animal. Rebleeding of the cauterized cuticle of the hemophilic animals did not usually occur. This model has considerable potential for the preclinical testing of products considered to bypass or replace factor VIII:C in patients with acquired inhibitors of factor VIII:C and may be adapted to the study of other mechanisms involved in normal and abnormal hemostasis.     

Existence of a pool of T-lymphocyte colony-forming cells (T-CFC) in human bone marrow and their place in the differentiation of the T- lymphocyte lineage

The existence and characteristics of bone marrow T-cell progenitors have not yet been established in man. Several pieces of evidence such as the reconstitution of certain immunodeficiencies by bone marrow graft suggest that T-cell precursors are present in the bone marrow. We report the growth of T-cell colonies from bone marrow populations using PHA-stimulated lymphocyte-conditioned medium containing T-cell growth factor (TCGF). Rosetting experiments and complement-dependent cytotoxicity assays with monoclonal antibodies indicate that the bone marrow T colony-forming cells (T-CFC) are E- OKT 3- and la+, i.e., immature progenitors. The colonies derived from these cells have the phenotype of mature T cells: E + OKT 3 + la- with either helper (OKT 4+) and suppressor (OKT 8 +) antigens. These results suggest that a thymic microenvironment may not be necessary for the in vitro proliferation and differentiation of the T-cell lineage in adult humans. These methodologies may permit direct investigation of early phenomena concerning the T-cell lineage, such as the acquisition of self-tolerance, the formation of a repertoire of specificities, and the HLA restriction phenomena that we believe takes place before the thymic maturation.     

儿童输注ABO主侧不合血小板的效果弱于输注血型相合的血小板

由于血小板只有5天的保存期,库存压力导致经常输注ABO血型不合的血小板.为了避免血小板过期,首先输注的是库存时间最长的血小板,包括输注ABO血型不合的血小板.AABB和英国血液学标准委员会建议,输注红细胞时必须要求ABO主侧相合,而输注血小板并没有要求ABO血型匹配.     

Doppler velocimetry in prolonged pregnancy

Eighty-two patients at 287 days' gestation or longer were tested by nonstress test (NST), amnioscopy, ultrasound assessment of amniotic fluid volume, and Doppler velocimetry. Several maternal and fetal arteries were analyzed: uterine, umbilical, descending thoracic aorta, renal, and middle cerebral. During the study, other maternal-fetal functional indices were recorded: hPL, estriol, hematocrit, platelets, mean platelet volume, and uric acid. No abnormalities were found in the uterine, umbilical, middle cerebral, thoracic descending aorta, and renal artery velocimetry in post-dates gestations. However, a significant reduction of the time-averaged mean velocity in the descending thoracic aorta was associated with an increased incidence of oligohydramnios, meconium-stained fluid, abnormal NST, and cesarean delivery for fetal distress. The present study suggests that serial Doppler flow measurements of mean velocity of the fetal descending thoracic aorta may be a simple and rapid technique for identifying prolonged pregnancies at increased risk for perinatal complications.     

Effect of oral contraceptives or dexamethasone on plasma beta-endorphin during the menstrual cycle

Several studies have showed a significant increase of plasma beta-endorphin levels during the periovulatory days of the menstrual cycle. The aim of the present study was to investigate the origin of the periovulatory changes of plasma beta-endorphin, trying to discriminate between a possible ovarian and/or pituitary origin. Daily plasma beta-endorphin, luteinizing hormone (LH), and cortisol levels were measured from the 8th to the 20th day of the menstrual cycle in healthy normal-cycling women (10 cases) before and during dexamethasone (DEX; 6 cases) or estroprogestinic treatment with monophasic (5 cases) or triphasic (5 cases) pill. In the control menstrual cycle, during the preovulatory days, a significant increase of plasma beta-endorphin was found. While oral contraceptives abolished the midcycle increase of plasma beta-endorphin, the periovulatory plasma beta-endorphin peak was present during DEX treatment. Plasma cortisol levels did not show any significant change throughout the control menstrual cycle, while they were significantly lowered by the DEX administration and significantly increased during estroprogestinic treatment. These results suggest that the increase of plasma beta-endorphin during the periovulatory days is related to the ovulatory function, and suggest a possible ovarian origin.     

Changes in beta-endorphin in fetal membranes and placenta in normal and pathological pregnancies

Several studies indicated that trophoblast tissue synthesizes pro-opiomelanocortin-related peptides. These peptides are also present in amniotic fluid, but their origin remains unknown. The present study evaluated the presence of and the possible changes in beta-endorphin (beta-EP) in amnion and chorion during pregnancy, at parturition and in spontaneous abortion. Amnion, chorion and placental tissues were isolated and homogenized from a total of 46 pregnant women between 4th and 42 th week of pregnancy. Beta-EP was separated on a Sephadex G-75 column and measured by RIA with specific antiserum. The identity of the endogenous opioid with its corresponding reference molecule was confirmed by high performance liquid chromatography. In all tissues, the concentration of beta-EP in the first trimester was significantly higher than in the second trimester. A negative correlation between opioid levels and gestational age was observed in the first two trimesters. At delivery, the beta-EP content of all tissues was greater than in the second trimester. In tissues collected at term, in the absence of labor, beta-EP levels were very low in comparison with those collected after vaginal delivery. Low beta-EP contents were found in membranes collected from spontaneous abortion in 1st trimester. From these data one can surmise the existence of a local endogenous opioid system in fetal adnexes. This system seems sensitive to the stress of vaginal delivery and could be involved in the mechanisms leading to spontaneous abortion.     

Domperidone in defective and insufficient lactation

The clinical use of anti-dopaminergic drugs to stimulate plasma PRL levels, to induce lactogenesis and maintain an adequate lactation has been widely suggested, taking into consideration the main inhibitory role of hypothalamic dopamine on PRL secretion. We therefore studied the effects of domperidone (DOM), a direct anti-dopaminergic drug with a low tendency to be secreted in the milk and which does not cross the blood-brain barrier, on inducing lactogenesis in 8 puerperal women with a history of defective lactogenesis (group A) and inducing galactopoiesis in 9 puerperal women who showed 2 weeks after delivery an insufficient lactation (group B). A placebo treatment was performed in 7 and 8 puerperal women with the same characteristics of group A and B, respectively. PRL plasma levels were assayed in basal conditions and after suckling from the 2nd to the 5th day of puerperium in group A and through a 10-day treatment in group B. In both groups domperidone-treated subjects always showed baseline PRL levels and daily milk yield significantly higher than those of the placebo group (P less than 0.01). The lack of any side-effects and the positive results suggest a high usefulness of such a drug in inducing and/or maintaining successful breast feeding, which is at present considered so important for a healthy development of infants.     

NAADP: an atypical Ca2+-release messenger?

Recently, nicotinic acid adenine dinucleotide phosphate (NAADP) has been shown, using different techniques, to mobilize intracellular Ca2+ stores in invertebrate, lower vertebrate, plant and mammalian cells. This endogenous molecule might play an atypical role in Ca2+ signalling by coordinating the responses of other Ca2+-releasing messengers. Furthermore, radioligand binding experiments have provided an insight into how desensitization of the NAADP receptor might occur.