Nucleotide polymorphisms in the alpha2 gene define multiple alleles that are associated with differences in platelet alpha2 beta1 density

Three allelic differences in the alpha2 gene are associated with expression levels of the alpha2beta1 integrin on the platelet surface. We have previously defined two linked silent polymorphisms in the alpha2 gene coding region at nucleotides 807 (C or T) and 873 (G or A). We have now identified one rarer nucleotide polymorphism in the coding region at nucleotide 837 (T or C) and four additional linked polymorphisms within the introns that flank these coding sequences. Moreover, we have determined that the alloantigenic Br polymorphism, which resides in a distal coding region at nucleotide 1648, is also linked to the 837 polymorphism. Thus, three alpha2 gene alleles, defined by eight nucleotide polymorphisms, have now been discovered. Allele 1 (807T/837T/873A/Brb) is associated with increased levels of alpha2beta1; allele 2 (807C/837T/873G/Brb) and allele 3 (807C/837C/873G/Bra) are each associated with lower levels of alpha2beta1. Finally, we also show here that the rate of platelet attachment to type I collagen in whole blood under conditions of high shear rate (1,500/s) is proportional to the density of alpha2beta1 receptors on the platelet surface. Thus, the density of platelet alpha2beta1 could have an important impact on platelet adhesion to collagen in whole blood and therefore on platelet function in vivo, contributing to an increased risk of thrombosis or to bleeding in relevant disease states.     

Analysis of fluid film lubrication in artificial hip joint replacements with surfaces of high elastic modulus

The endocytic pathway of Tritrichomonas foetus, a parasitic protozoan of cattle, was studied using (a) vital dyes, such as Lucifer yellow, neutral red and acridine orange, (b) cationized ferritin, (c) gold-labeled lactoferrin and lectins: HPA, UEA, PNA and LPA, and (d) DAMP (3-(2,4-dinitroanilino) 3' amino-N-methyldipropylamine). Light and confocal laser microscopy as well as transmission electron microscopy were used in this study. Assays were monitored by fluorescence and electron microscopy after exposing the parasites to different conditions. Cells that were incubated at 15 degrees C or 20 degrees C with gold-labeled lactoferrin and processed for electron microscopy show that of 15 degrees C this ligand is found only in an early endosomal compartment and at 20 degrees C it is found in late endosomes but not in lysosomes. Immunocytochemical data from cryosections using DAMP as a pH probe show that T. foetus has acidic compartments, with a pH range of 5.2 to 6.6, with variable morphology, localization and size. Lectin-binding sites and anionic sites were also internalized and appear to be associated with membranes lining the vacuoles. Images of patching and shedding of these sites were also observed when HPA and UEA were used.     

Nitric oxide-mediated changes in vascular reactivity in pregnancy in spontaneously hypertensive rats

1. To examine the mechanisms which may account for pregnancy-induced vasodilatation in spontaneously hypertensive rats (SHR), we have investigated the changes in vascular reactivity and the effects of endothelial nitric oxide (NO) inhibition in the in situ blood-perfused, mesenteric resistance vessels of 18-20 day pregnant SHR. The effects of NG-nitro-L-arginine (L-NOARG) were compared in pregnant and nonpregnant SHR and gestation matched normotensive Wistar-Kyoto (WKY) rats. 2. Intra-arterial mean blood pressures (MBP) were similar in pregnant and nonpregnant SHR. Basal perfusion pressures (BPP) were decreased in pregnant compared with nonpregnant SHR. Pregnant WKY had lower MBP and BPP than either pregnant or nonpregnant SHR. 3. Vasoconstrictor responses to electrical stimulation (ES) and intra-arterial noradrenaline (NA) were decreased in pregnant compared with nonpregnant SHR. These responses were still greater in pregnant SHR when compared with pregnant WKY. Vascular reactivity to angiotensin II (AII) in pregnant SHR was reduced to a similar level to that in pregnant WKY. 4. L-NOARG (5 mg kg-1, i.v.), an inhibitor of nitric oxide synthase, increased MBP and BPP in all groups. After L-NOARG, BPP were equalized between pregnant and nonpregnant SHR. Pregnant WKY still showed lower MBP and BPP than SHR groups. 5. L-NOARG potentiated vascular responses to ES, NA and AII in all groups. The blunted vascular responses to NA and ES were normalized and the reactivity to AII was only partially reversed in pregnant SHR compared with nonpregnant SHR. Pregnant WKY still had much lower vascular responses to ES and NA than either pregnant or nonpregnant SHR. L-NOARG enhanced vascular responses to All to a greater extent in pregnant SHR than in pregnant WKY.6. These results demonstrate that blunted responses to NA and ES were NO-dependent, while diminished reactivity to AII was only partially dependent on NO in the in situ blood perfused mesenteric resistance vessels of pregnant SHR.7. The present results in pregnant SHR differ from our previous finding with pregnant normotensive WKY, in which blunted responses to NA, but not to ES, were equalized by L-NOARG. Pregnancy induced vasodilatation in hypertensive rats appears to be more dependent on endothelial NO than in normotensive WKY. A defect of the endothelial NO generating pathway which promotes vasodilatation in pregnancy may contribute to the predisposition of women with essential hypertension to develop pre-eclampsia.     

A controlled trial of HA-1A in a canine model of gram-negative septic shock

OBJECTIVE: To investigate the therapeutic efficacy and microbiological and physiological effects of a human IgM monoclonal antibody (HA-1A) directed against the lipid A component of endotoxin in a canine model of sepsis that simulates the cardiovascular abnormalities of human septic shock. DESIGN: Blinded, placebo-controlled 28-day trial. INTERVENTIONS: Purpose-bred beagles were implanted with an intraperitoneal clot infected with Escherichia coli O111:B4. At clot placement, animals received HA-1A (10 mg.kg-1), control human IgM antibody (10 mg.kg-1), or control human serum albumin intravenously. All animals were given antibiotic and fluid therapy. MEASURES: Survival and microbiological and physiological events. RESULTS: Only two (15%) of 13 animals in the HA-1A group, compared with eight (57%) of 14 control animals (combined control human IgM antibody and control human serum albumin groups) (P = .05), survived 28 days. At 24 hours, the HA-1A group had lower mean arterial pressure (P = .04) and cardiac index (P = .004) and higher lactate levels (P = .05) compared with the combined-controls group. In addition, these parameters in the HA-1A group were significantly more predictive of death. The HA-1A and combined-controls groups had similar significant increases in the level of endotoxemia and bacteremia. Studies of toxic effects showed no harmful effects of control human IgM antibody in infected animals or HA-1A in non-infected animals. CONCLUSION: In a canine model of E coli sepsis, HA-1A did not alter levels of bacteremia or endotoxemia and actually decreased survival. If these data are relevant to human septic shock, HA-1A therapy should be limited until the conditions under which this monoclonal antibody has beneficial or deleterious effects are more completely defined.     

Role for cell surface oligosaccharide in cell-cell recognition during implantation

OBJECTIVE: To evaluate the effect of three different dosages of transdermally administered 17beta-estradiol on serum lipoproteins in women who had recently experienced surgical menopause. MATERIAL AND METHODS: We undertook a 2-year, randomized, double-blind, placebo-controlled study in which 126 subjects were recruited and stratified by age, and 93 patients completed the protocol. Serum lipoproteins were assessed before initiation of treatment and after 12 and 24 months of therapy with 0.025, 0.05, or 0.1 mg of estradiol daily. RESULTS: Total serum cholesterol and low-density lipoprotein cholesterol showed dose-dependent decreases that reached statistical significance after 2 years of treatment with transdermally administered estradiol. CONCLUSION: This study confirms that transdermally administered 17beta-estradiol has a modest beneficial effect on serum lipoproteins, with decreased levels of total cholesterol and low-density lipoprotein cholesterol.     

Effect of immunomodulators pyrimethamine and cimetidine on immunosuppression induced by sulfur mustard in mice

A corticotropin-releasing hormone (CRH) stimulation test with four cumulative doses of human CRH (0.01, 0.06, 0.2 and 1 microgram/kg body weight) and infusion of a low dose of [Arg8]-vasopressin (0.004 U/kg body weight/30 min) was performed in five depressed patients and six healthy subjects. Plasma samples for the measurement of cortisol, ACTH and beta-endorphin were taken at regular intervals and considered as measures of pituitary-adrenal function. A dose-response relationship between CRH and the hormones measured was found in patients and controls. Depressed patients already responded to the lowest dose of CRH with respect to cortisol release, whereas ACTH and beta-endorphin responded to the second and third doses, respectively. In control subjects the cortisol and ACTH response started after the third dose of CRH, whereas beta-endorphin responded significantly to the highest dose only. When both groups were compared, differences in response were found to the higher doses of CRH with respect to cortisol, ACTH and, less markedly, beta-endorphin and to the lowest dose of CRH with respect to cortisol. Although numbers are small, the data show 'blunting' of the ACTH response to the higher doses of CRH in patients with an enhanced cortisol response of the adrenals to lower and higher doses of CRH. There was no significant difference in response when CRH was used with vasopressin as compared to treatment with CRH alone. Thus, in this design vasopressin did not contribute significantly to CRH activity. The data suggest that pituitary cell sensitivity might be changed in depression as part of HPA dysfunction.     

Twenty years of research on B-cell chronic lymphocytic leukemia

The typical MRI features of the most common pancreatic diseases, such as pancreatitis and adenocarcinoma of the pancreas, have been established. However, even in these common pancreatic disorders, MRI correlation with the underlying pathology is limited for clinical reasons. We emphasize MR-pathological correlation of inflammatory and neoplastic pancreatic changes, including pancreatitis, adenocarcinoma, acinar cell carcinoma, rare cystic and solid pancreatic neoplasms, and islet cell tumors. By highlighting the correlation of key pathological features with MR findings, a better understanding of the MR appearance of pancreatic pathology can be provided. In addition, MRI may prove a powerful tool in detection and characterization of pancreatic tumors.