Erythrocyte-endothelial cell adherence in sickle cell disease,diabetes mellitus,and falciparum malaria: Adverse effects reversed with Piracetam

The erythrocytes of patients with sickle hemoglobin, diabetes, and Falciparum malaria adhere disproportionately to endothelial cells. Such pathophysiological activity compromises the microcirculation and results in clinical disease. Since Piracetam (2-oxo-1 pyrrolidine acetamide) has been shown to have a number of clinically beneficial actions on the formed elements of the blood including disengagement of adherent diabetic and sickle erythrocytes there is a rational basis for the trial of Piracetam as an adjuvant drug in SS disease and in diabetes mellitus to improve function of the microcirculation. For similiar but somewhat more complex reasons Piracetam may potentiate the efficacy of anti-malarial drugs at any given dosage. Piracetam, a drug known to be safe in a decade of clinical usage, merits serious study in the 3 cited diseases.     

Hemoglobin S-mediated membrane oxidant injury: protection from malaria and pathology in sickle cell disease

It is suggested here that a Hemoglobin S (HbS)-mediated membrane oxidant injury is responsible for both the protection from malaria infection in the heterozygous sickle cell state, and for a critical pathologic process in homozygous sickle cell disease. This suggestion is arrived at by applying to the HbS condition the oxidant stress model for malaria resistance. Such a model had been developed to explain the protection from malaria in thalassemia and in glucose-6-phosphate dehydrogenase (G6PD) deficiency (9).     

Upregulation and atypical expression of the CD1 molecules on monocytes in sickle cell disease

Human CD1 group I molecules CD1a, b, and c are expressed on antigen-presenting cells, notably dendritic cells, and implicated in glycolipids presentation to T lymphocytes. Expression of CD1 on monocytes is a hallmark of their activation. Because monocyte activation has been reported during steady state disease in sickle cell anemia (SCA) patients, we have analyzed CD1 expression on monocytes from 45 SCA patients originating from Africa and 27 healthy control subjects. CD1 expression was detected on monocytes in the majority of SCA patients (75%), whereas it was not observed in the vast majority of the control group (70.4%). CD1b and CD1c were highly expressed in Sbeta thalassemia patients and CD1a expression was predominant in SDPunjab patients. This expression of the CD1 molecules is correlated with an increased expression of the major histocompatibility complex class II invariant chain (CD74). Finally, we have observed that the majority of SCA patients (68%) express only two or one CD1 isoforms. This study demonstrates the particular phenotype of SCA monocytes intermediate between normal resting and activated monocytes, a phenotype that could have consequences on regulation of the infection outcome.     

Studies on iron metabolism in sickle cell anaemia, sickle cell haemoglobin C disease, and haemoglobin C disease using a large volume liquid scintillation counter

Iron absorption as measured by a faecal recovery method in young adult males living in a tropical zone was high, even in the absence of anaemia. There was an inverse relation between the iron absorption and the packed cell volume. The highest absorption was found in sickle cell anaemia patients, where the packed cell volume is the lowest. The incorporation of iron was also the fastest and greatest in this group. In the controls the iron absorbed accumulated in the marrow and the spleen on the first day; in the sickle cell anaemia group the spleen has an insignificant role in iron storage. The growing radioactivity in the liver parallels that of the heart in the group of sickle cell anaemia patients; however, it remains low in the spleen in the same group, implying a diminution of splenic blood flow. In the sickle cell haemoglobin C and the haemoglobin C patients, the liver and spleen have an intermediate position between that of the sickle cell anaemia group and the control group.     

Large-vessel occlusion in sickle cell disease: pathogenesis, clinical consequences, and therapeutic implications

Much of the morbidity and mortality in sickle cell disease (SCD) is caused by tissue ischemia and infarction resulting from vascular occlusion. Research in this area has been dominated by the hypothesis that vascular occlusion in SCD is due primarily to microvascular obstruction by sickle erythrocytes (SS RBC), yet there is no direct evidence that microvascular occlusion is responsible for any of the vasocclusive complications of SCD. In this paper an alternate hypothesis is proposed: that thrombotic occlusion of larger arteries and veins is an important factor in many of the vasocclusive complications of SCD. Large-vessel cerebral arterial disease (intimal hyperplasia with superimposed thrombosis) has clearly been established as the most important cause of stroke in SCD, and considerable evidence suggests that pulmonary arterial thrombosis/embolism is a major cause of pulmonary infarction and hypertension. The involvement of large-vessel thrombosis in painful crisis, aseptic necrosis of bone, priapism, leg ulcers, retinopathy, and miscarriage has not been adequately investigated. Large-vessel occlusion in SCD is probably a consequence of the abnormal adhesive and procoagulant properties of SS RBC, which produce endothelial damage, secondary intimal proliferation, and thrombosis. Techniques currently used to treat large-vessel occlusion in other disorders (antiplatelet and anticoagulant agents, thrombolytic therapy, angioplasty, endarterectomy, and vascular bypass surgery) should be considered in sickle cell subjects with large-vessel occlusion, especially in the cerebral vasculature.     

Synthesis of opioidmimetics, 3-[H-Dmt-NH(CH(2))(m)]-6-[H-Dmt-NH(CH(2))(n)]-2(1H)-pyrazinones, and studies on structure-activity relationships

Opioidmimetics containing 3-[H-Dmt-NH-(CH(2))(m)]-6-[H-Dmt-NH-(CH(2))(n)]-2(1H)-pyrazinone symmetric (m = n, 1-4) (1 - 4) and asymmetric (m, n = 1 - 4) aliphatic chains (5 - 16) were synthesized using dipeptidyl chloromethylketone intermediates. They had high mu-affinity (K(i)mu = 0.021 - 2.94 nM), delta-affinity (K(i)delta = 1.06 - 152.6 nM), and mu selectivity (K(i)delta/K(i)mu = 14 - 3,126). The opioidmimetics (1 - 16) exhibited mu agonism in proportion to their mu-receptor affinity. delta-Agonism was essentially lacking in the compounds except (4) and (16), and (1) and (2) indicated weak delta antagonism (pA(2) = 6.47 and 6.56, respectively). The data verify that a specific length of aliphatic linker is required between the Dmt pharmacophore and the pyrazinone ring to produce unique mu-opioid receptor ligands.     

Immunology: Distribution of cell adhesion molecules on CD56++, CD3-, CD16- large granular lymphocytes and endothelial cells in first-trimester human decidua

Human decidua exhibits a unique infiltrate of large granularlymphocytes (LGL) with a natural killer (NK) cell phenotype(CD56++, CD16–, CD3–). The mechanisms underlyingthe binding of circulating LGL to vascular endothelium in thedecidua and their migration into the decidual stroma were investigatedimmunohistochemically in first-trimester decidua with antibodiesagainst endothelial adhesion molecules and their counter-receptorson leukocytes. Decidual and peripheral blood LGL were also investigatedby flow cytometry. In the immunohistochemical investigations,moderate to large numbers of lymphoid cells in the decidua werefound to express the ₄ and _L integrin subunits, platelet endothelialcell adhesion molecule (PECAM) and intercellular adhesion molecule-1(ICAM-1). PECAM and ICAM-1 were found on the endothelium oflarge numbers of decidual blood vessels of all types. Vascularcell adhesion molecule (VCAM), however, was found on the endotheliumof only small to moderate numbers of arterioles and venulesand a few capillaries, the latter being the main site of migrationof leukocytes into the stroma. Weak staining for endothelialleukocyte adhesion molecule (ELAM) was seen only in a moderatenumber of blood vessels. Flow cytometry revealed expressionof the _L integrin subunit by 72 ± 10% and 97 ±3% of decidual and peripheral blood CD56+ LGL, respectively,of the 4 integrin subunit by 85 ± 7% and 90 ±5%, of PECAM by 40 ± 12% and 30 ± 15%, and ofICAM-1 by 22 ± 10% and 1 ± 1%. These findingssuggest that interaction between the integrin _2L and ICAM-1is the more important mechanism of binding to endothelium inthe migration of CD56+ LGL out of the peripheral blood intothe decidua.     

In vitro influence of albumin, gammaglobulin and fibrinogen on the sedimentation rate and the rheological behaviour of the red cell (author's transl)]

The complexity of the mechanisms which enter into play in the phenomenon of erythrocyte sedimentation have for long aroused the curiosity of research workers. A simultaneous study of this parameter and of the viscosity, of the relative zeta potential together with the osmotic fragility, led us to appreciate the respective actions of three isolated plasma proteins : albumin, immunoglobuin G, fibrinogen, on the ESR and on the rheological properties of the red cell.     

CD80 (B7-1) and CD86 (B7-2) antigens on house dust mite-specific T cells in atopic disease function through T-T cell interactions

BACKGROUND: CD80 (B7-1) and CD86 (B7-2) play an important role in antigen presentation to effector cells. Recent studies have demonstrated that these costimulatory molecules are also expressed on activated T cells. However, the functional role of CD80 and CD86 expressed on allergen-specific T cells in atopic diseases has not yet been clarified. OBJECTIVE: We sought to determine the functional role of CD80 and CD86 expressed on allergen-specific T cells in atopic diseases. METHODS: We assayed the expression of CD80 and CD86 on allergen-specific T-cell lines from patients with perennial allergic rhinitis stimulated by Dermatophagoides farinae-crude (Der f-c) antigen, 1 of the major allergens causing house dust mite allergy. T-cell proliferation induced by Der f-c-specific T-T cell interactions was measured, and the role of CD80 and CD86 in this proliferation was examined. In addition, we compared the proportion of CD45RO+CD86(+) T cells in primary culture of PBMCs stimulated by Der f-c antigen between patients with perennial allergic rhinitis and control subjects. RESULTS: On T-cell activation, CD86 antigen was upregulated earlier than CD80. Both CD80 and CD86 expressed on Der f-c-specific T cells could provide costimulatory signals to induce allergen-specific T-cell proliferation that was partially inhibitable by both anti-CD80 and anti-CD86 mAbs. The proportion of CD45RO+CD86(+) T cells in primary culture from atopic patients was significantly higher than that from control subjects. CONCLUSION: These results suggest that costimulatory molecules, such as CD80 and CD86, expressed on allergen-specific T cells may be involved in the amplification of allergen-specific immune responses through T-T cell interactions in atopic diseases.     

Impact of environmental changes and human-related factors on the potential malaria vector, Anopheles labranchiae (Diptera: Culicidae), in Maremma, Central Italy

The Maremma Plain (central Italy) was hyper-endemic for malaria until the mid-20th century, when a national campaign for malaria elimination drastically reduced the presence of the main vector Anopheles labranchiae Falleroni. However, the introduction of rice cultivation over 30 yr ago has led to an increase in the An. labranchiae population and concern over possible malaria reemergence. We studied the impact of anthropogenic environmental changes on the abundance and distribution of An. labranchiae in Maremma, focusing on rice fields, the main breeding sites. Adults and larvae were collected in three main areas with diverse ecological characteristics. Data were collected on human activity, land use, and seasonal climatic and demographic variations. We also interviewed residents and tourists regarding their knowledge of malaria. Our findings showed that the most important environmental changes have occurred along the coast; An. labranchiae foci are present throughout the area, with massive reproduction strictly related to rice cultivation in coastal areas. Although the abundance of this species has drastically decreased over the past 30 yr, it remains high and, together with climatic conditions and the potential introduction of gametocyte carriers, it may represent a threat for the occurrence of autochthonous malaria cases. Our findings suggest the need for the continuous monitoring of An. labranchiae in the study area. In addition to entomological surveillance, more detailed knowledge of human-induced environmental changes is needed, so as to have a more complete database that can be used for vector-control plans and for properly managing emergencies related to autochthonous introduced cases.     

Vaccination against malaria: initial trial with an ant-sporozoite vaccine, (NANP)3-TT (RO 40-2361) in Africa (Bobo-Dioulasso, Burkina Faso)

The vaccine (NANP)3-TT is a synthetic peptide of the circumsporozoite protein (CS) of Plasmodium falciparum coupled to tetanus toxoid (TT) as protein carrier and adsorbed to aluminium hydroxide as adjuvant. The objectives of the study were to assess the immunogenicity and the protective efficacy of the vaccine in an area where malaria is endemic. The study was conducted in a zone of irrigated rice cultivation known as the Vallée du Kou to the North of Bobo-Dioulasso. Malaria transmission is permanent in the Vallée with maxima in July and November. The study was conducted from June to December 1988. It was a controlled randomised, double blind, prospective vaccine trial. A total of 123 infants from 3 to 5 months of age were randomly assigned to three groups. Group I (controls) received three doses of TT alone, group II received two doses of TT and one of (NANP)3-TT and group III received three doses of (NANP)3-TT. These vaccines were administered simultaneously with the Enlarged Program of Immunisation (EPI) vaccines. The clinical parasitological and immunological status of the children was then monitored over a period of five months. No systemic reactions to the vaccine were observed in the infants either immediately after administration or during the follow-up. Minor local tumefactions were observed in only 3% of the children. The vaccine was found to be immunogenic with a peak IgG response at day 75, when 56% (group II) and 60% (group III) showed antibody titres of at least four times that seen at day 0. The response, however, was a short duration; by day 150 the average antibody titres were not significantly different between the three groups. The incidence and the level of parasiaemia and the incidence of clinical malaria were also not significantly different for each of the three groups during the period of the study. The association of (NANP)3 with tetanus toxoid was not shown to be immunologically inhibitive. The results, despite not showing a protective effect for the vaccine (NANP)3-TT, have shown its immunogenicity and therefore suggest that further development of this vaccine may be worthwhile.     

Influence of metals and non-steroid anti-inflammatory drugs on the activity of human red cell ALA dehydratase "in vitro" (author's transl)]

The effect of metals and drugs on the activity of human erythrocyte ALA dehydratase has been studied in vitro. The most inhibitory metals are with decreasing effect silver, copper, gold and selenium. Zinc, cadmium, mercury are inhibitory at high concentrations and activator at low concentrations. Arsenic, calcium, magnesium, manganese, potassium, cobalt have no effect. Within the drugs studied the non steroidal anti-inflammatory drugs (aspirin, keptoprofen, indometacin, phenylbutazone, sodium salicylate and niflumic acid) are the only group which inhibits the enzyme ALA dehydratase. This inhibition is suppressed by zinc. The non steroidal anti-inflammatory drugs can inhibit the activity of enzymes which need zinc for optimal activity.