Use of elimination of plasma phospholipid membranes for detection of "lupus anticoagulant" effects

The coagulation activity of plasma phospholipid membranes (PM) was measured in plasma depleted for platelets (PDP) in 50 normal subjects and 33 patients with the antiphospholipid syndrome (APS) and the "lupus anticoagulant" in the plasma. The normal value for phospholipid activation of clotting was 99.8 +/- 3.5% (from 75 to 125%), whereas in patients with APS and lupus anticoagulant it was 42.1 +/- 8.2% (p < 0.001). Addition of PM from patients' PDP to normal plasma free from PM did not normalize clotting. Addition of PM from normal plasma to patients' PDP normalized the clotting time. Therapy with discrete plasmapheresis increased the phospholipid activation value in the patients from 42.1 to 73.3% (p < 0.01), which was due to removal of the PM-antiphospholipid antibody complex from PDP. The proposed microfiltration method can be used in the complex of tests for detecting the lupus anticoagulant in patient's plasma.     

Response to symptom-limited exercise in patients with the hepatopulmonary syndrome

OBJECTIVE: To study the response to symptom-limited exercise in patients with the hepatopulmonary syndrome (HPS). DESIGN: The response to maximal cardiopulmonary exercise (CPX) was studied in 5 patients with HPS and compared with 10 case control (normoxemic, NC) cirrhotics (matched for age, gender, etiology and severity of liver disease, tobacco use, and beta-blocker therapy) and 9 hypoxemic control cirrhotics (HC) without clinical evidence of HPS. SETTING: Cardiopulmonary exercise physiology laboratory in a tertiary care referral center. PATIENTS: Cirrhotics referred for CPX as part of their preliver transplantation evaluation. MEASUREMENTS: Standard pulmonary function tests and echocardiography were performed to assess resting pulmonary and cardiac function. Peak oxygen consumption (VO2), minute ventilation, arterial blood gases, and dead space (VD/VT) were determined during symptom-limited maximal CPX. RESULTS: Resting spirometry and lung volumes were similar between HPS and NC subjects, while HC subjects had restrictive physiology. Differences existed in diffusing capacity corrected for hemoglobin and alveolar volume percent predicted (HPS, 45+/-2 vs NC, 68+/-3, p<0.05; vs HC, 70+/-4, p<0.05), PaO2 (HPS, 70+/-5 mm Hg; HC, 79+/-3 mm Hg, vs NC, 102+/-3 mm Hg, p<0.05) and alveolar-arterial (A-a) O2 gradient (HPS, 42+/-8 mm Hg vs HC, 27+/-2 mm Hg, p<0.05; vs NC, 6+/-2 mm Hg, p<0.05). During CPX, HPS patients achieved a lower peak VO2 percent predicted (HPS, 55+/-6 vs NC, 73+/-3, p<0.05; vs HC, 71+/-5, p<0.05) and VO2 at the ventilatory threshold as percent predicted peak VO2 (HPS, 36+/-2 vs NC, 55+/-4, p<0.05; vs HC 55+/-5, p<0.05). While no differences existed in heart rate and breathing reserve, HPS patients had significantly lower PaO2 (HPS, 50+/-5 mm Hg vs NC, 97+/-4 mm Hg, p<0.05; vs HC, 87+/-6 mm Hg, p<0.05), wider A-a O2 gradient (HPS, 73+/-5 mm Hg vs NC, 13+/-3 mm Hg, p<0.05; vs HC, 31+/-5 mm Hg, p<0.05) and higher VD/VT (HPS, 0.36+/-.03 vs NC, 0.18+/-.02, p<0.05; vs HC, 0.28+/-.02, p<0.05) at peak exercise. For HPS patients, VO2 was negatively correlated with VD/VT (r2=0.9) and positively correlated with PaO2 (r2=0.41) at peak exercise. Conclusions: Patients with HPS demonstrate a severe reduction in aerobic capacity, beyond that found in cirrhotics without syndrome. The significant hypoxemia and elevated VD/VT at peak exercise suggest that an abnormal pulmonary circulation contributes to further exercise limitation in patients with HPS.     

Experimental biology and NASA in the twenty-first century

Cardiopulmonary bypass (CPB) causes activation of cascade systems. Although heparin coating of CPB circuits improves biocompatibility, the effects on coagulation remain controversial. Theoretically, heparin coating should permit the reduction of systemic anticoagulation during CPB. We investigated influences on haemostatic variables in animal CPB, comparing heparin-coated circuits and reduced systemic heparinization (group HC) with uncoated circuits and full heparinization (group C). Twenty pigs underwent 2-h CPB. Seven (HC, n = 4; C, n = 3) were weaned from CPB and studied for up to 4 h. Total administered heparin was 470 +/- 6 IU/kg (mean +/- SEM) in group C and 100 +/- 0 IU/kg in group HC. Protamine dosage was significantly reduced in group HC. In group C, levels of prothrombin complex, factor VIII and adhesive platelets were reduced significantly during CPB, and postoperatively there were significantly lower values of prothrombin complex, fibrinogen antithrombin III, factor VIII and adhesive platelets but a significantly increased concentration of von Willebrand factor and cumulative bleeding after 4 h. In conclusion, heparin-coated CPB circuits combined with lowered heparin dosage reduced coagulation factor consumption and preserved platelet function, possibly contributing to improved postoperative haemostasis.     

Platelet sialic acid and platelet survival after aggregation by ADP

Some investigators have reported recently that platelet surface sialic acid is decreased during ADP-induced aggregation, whereas others have reported an increase. Since removal of sialic acid from the platelet surface shortens platelet survival, we have determined the survival of platelets that have been aggregatad by ADP. We have also measured the amount of sialic acid in the suspending fluid of platelets after ADP-induced aggregation. ADP-induced aggregation did not cause the loss of sialic acid from rabbit platelets (which do not undergo a release reaction in response to ADP) nor from washed human platelets in a medium containing physiologic concentrations of calcium in which granule contents are not released. In a medium without added calcium, ADP caused the release of 14C-serotonin (42.5% +/- 3%) from human platelets, but less than 4% of the sialic-acid-containing material was released. It seems likely that little of the releasable sialic acid of platelets is in the dense granules or the alpha-granules. Thrombin (5 U/ml) released 90.0% +/- 3.4% of the serotonin from human platelets but only 20.6% +/- 7.4% of the total sialic-acid-containing material. Neuraminidase removed 42.3% of the total sialic acid, presumably from the platelet surface. Rabbit platelets that had been aggregated by ADP and deaggregated survived normally when returned to the circulation. This observation also provides evidence that they had not lost membrane sialic acid during aggregation and deaggregation.     

Effect of pravastatin treatment on glucose, insulin, and lipoprotein metabolism in patients with hypercholesterolemia

Treatment of patients with type IIA hyperlipoproteinemia (HLP) with pravastatin for 3 months led to significant decreases (p < 0.001) in total cholesterol (7.18 +/- 0.30 to 5.75 +/- 0.30 mmol/L), LDL cholesterol (5.56 +/- 0.33 to 4.02 +/- 0.32 mmol/L), and ratio of total cholesterol to HDL cholesterol (6.5 +/- 0.4 to 4.6 +/- 0.4). Decreases of a similar magnitude were also seen in patients with type IIB HLP. Plasma glucose and insulin concentrations after an oral glucose load and from 8 AM to 4PM in response to meals were higher in patients with Type IIB HLP, who also had higher steady-state plasma glucose concentrations after an infusion of somatostatin, insulin, and glucose (12.4 +/- 1 vs 5.5 +/- 0.8 mmol/L, p < 0.001). Because steady-state plasma insulin concentrations were similar in both groups, patients with type IIB HLP were relatively insulin resistant. Furthermore, day-long plasma glucose concentrations and insulin resistance were modestly, but significantly (p < 0.01), greater after treatment in both groups. In conclusion, LDL cholesterol metabolism improved in hypercholesterolemic subjects treated with pravastatin, but the hypertriglyceridemia, insulin resistance, relative glucose intolerance, and hyperinsulinemia present in patients with type IIB HLP either did not improve with treatment or was somewhat worse.     

Increased sensitivity of the cough reflex in progressive systemic sclerosis patients with interstitial lung disease

Cough is a common presenting symptom of interstitial lung disease (ILD). The aim of this study was to examine the cough reflex in patients with progressive systemic sclerosis (PSS), with and without associated ILD. The cough reflex to inhalation of chloride deficient solutions and capsaicin was determined in patients with PSS with associated ILD (n=12), compared to patients with PSS without ILD (n=12). In addition, patients with a chronic dry cough (n=12) and healthy subjects (n=10) without cough were studied. Cough responses to inhalation of isotonic solutions containing 150, 75, 37.5 and 0 mM Cl- ions and of capsaicin (0.9-500 mM) were measured. PSS patients with ILD reported a significantly higher cough score than PSS patients without ILD (p<0.03). ILD patients coughed more than those without ILD to Cl- of 37.5 and 0 mM (19.1+/-5.0 vs 6.2+/-1.9 coughs x min(-1) (p<0.03), and 29.2+/-5.0 vs 14.1/-4.1 coughs x min(-1) (p<0.04), respectively). The log concentration of capsaicin causing two or five coughs was lower in PSS with ILD compared to PSS without ILD (0.74+/-0.15 mM vs 2.12+/-0.26 mM; p<0.002). Patients with chronic dry cough had a similar degree of response to low-chloride and capsaicin solutions as patients with PSS and ILD, whilst healthy controls had a similar degrees of response to PSS patients. There is an increased cough reflex in patients with interstitial lung disease, which may represent sensitization of airway sensory nerves. This may be the basis for the chronic dry cough in patients with interstitial lung disease.     

Effect of aerosol heparin on the development of hypoxic pulmonary hypertension in the guinea pig

Chronic hypoxia produces pulmonary artery hypertension through vasoconstriction and structural remodeling of the pulmonary vascular bed. The present study was designed to test the effect of heparin administered via aerosol on the development of hypoxic pulmonary hypertension. Anesthetized, intubated, and mechanically ventilated guinea pigs received an aerosol of either 2 ml normal saline (hypoxic control, HC) or 4,500 units of heparin diluted in 2 ml normal saline via an ultrasonic nebulizer (hypoxic heparin, HH). After 24 h of recovery, the animals were placed in a hypoxic chamber (10% O2) for 10 days. Animals kept in room air served as normoxic controls (NC). Hypoxia increased mean pulmonary artery pressure from 11 +/- 1 (SEM) mm Hg in NC to 24 +/- 1 mm Hg in HC (p < 0.05). Pulmonary artery pressure was significantly lower in HH-treated animals (20 +/- 1 mm Hg, p < 0.05 versus HC) as was the total pulmonary vascular resistance (0.15 +/- 0.01 in HH versus 0.20 +/- 0.01 mm Hg/ml/min in HC, p < 0.05). There was no difference in cardiac output (146 +/- 12 in HH versus 126 +/- 7 ml/min in HC), hematocrit (57 +/- 2 in HH versus 56 +/- 2% in HC), partial thromboplastin time (30 +/- 2 in HH versus 32 +/- 3 s in HC), prothrombin time (46 +/- 1 in HH versus 48 +/- 4 s in HC) or room air arterial blood gas values after 10 days of hypoxia.(ABSTRACT TRUNCATED AT 250 WORDS)     

Rapid separation of cytosol and particle fraction of human platelets by digitonin-induced cell damage

Current cell disruption and fractionation techniques are time consuming and unsuitable for metabolic studies. We have developed a rapid method for platelets in which separation of cytosol and particle fraction is obtained within 50 s. Isolated platelet suspensions were incubated with low concentrations of digitonin followed by separation of soluble and particle fraction by centrifugation through a phthalate layer. Cell disruption was 90.1+/-4.2% (mean+/-SD, n=18; lactate dehydrogenase leakage). Contamination of granules: acid hydrolase vesicles 16.2+/-3.6% (n=18, beta-N-acetylglucosaminidase), dense granules 7--9% (n=3, 14C-serotonin), mitochondrial matrix 0.6+/-0.1% (n=18, glutamate dehydrogenase). Low concentrations of digitonin did not affect sialic acid content, nucleoside diphosphate kinase and phosphodiesterase activity in isolated membranes. The method showed that most enzymes of glycolysis and hexose monophosphate shunt were localized in the cytosol except for hexokinase (96% particle bound), phosphoglucose isomerase (10% bound) and glutathion reductase (26% bound). About half the total ATP+ADP and most glycolytic intermediates were found partly particle bound, especially fructose 1,6-diphosphate (40% bound). The data suggest that in platelets glycolysis occurs in different cell compartments.     

The effect of recombinant human erythropoietin on cardiovascular responses to postural stress in dialysis patients

The normal response to 45 degrees head-up tilt (decreased stroke volume and cardiac output and increased heart rate and peripheral resistance) is not seen in the majority of haemodialysis patients. This is due to both an abnormal baroreceptor reflex and increased venous tone which may be explained by a number of factors including hypoxia, acidosis and sodium retention. We have studied this response by impedance cardiography in eight chronic haemodialysis patients, both before and after 3 months of treatment with human recombinant erythropoietin. Before treatment the cardiovascular parameters were abnormal both at rest and on tilting in each patient. The change in each measurement following tilting was: stroke volume, 0.5 +/- 6%; cardiac output, 6 +/- 5%; peripheral resistance, -8 +/- 4%; and heart rate, 10 +/- 4%. After 3 months of erythropoietin (150 U/kg/week intravenously) the mean haematocrit had risen from 19.5 +/- 3% to 32.9 +/- 4% and all patients felt physically fitter. Impedance showed no change in the supine-indices but after tilting there was a dramatic fall in stroke volume (-26 +/- 7%) and cardiac output (-17 +/- 7%) and an increase in heart rate (15 +/- 4%) and peripheral resistance (28 +/- 10%) each moving towards the normal response. These results indicate that human recombinant erythropoietin normalizes the response to postural stress in these patients and suggest that anaemia is the principal cause of the abnormal venoconstriction seen in haemodialysis patients. The mechanisms involved warrant further investigation.     

The tight junctions of the leptomeningeal blood-cerebrospinal fluid barrier during development

The outer blood-cerebrospinal fluid barrier is formed by leptomeningeal cells of the arachnoidea. The structures underlying this barrier are tight junctions. In contrast to the tight junctions of endo- and epithelial cells, which have been investigated by means of ultrastructural as well as by molecular methodology, equivalent studies on meningeal cells are lacking. In the present study, therefore, the ultrathin section and freeze-fracture morphology of cranial leptomeningeal cells of carp, frog, chicken and rat was investigated by quantitative morphometry. In addition, the developmental features of the meningeal barrier in chicken and rat were compared. The parameters determined were the complexity of the tight junctions, the density of strands and branchpoints and the degree of association of tight junction particles with the protoplasmatic and exoplasmatic leaflets of cellular membranes. The complexity of tight junctions was highest in chicken and lowest in frog meningeal cells, whereas intermediate values were reached in the carp and the rat. E- and P-face associations were similar in carp and frog, whereas in chicken, the P-face association and in rat the E-face association dominated. During development, tight junction complexity continuously increased up to adult stages in the chicken, whereas in the rat, the adult value was already reached at postnatal day 2. At early embryonic stages, particle insertion into tight junctions was incomplete but occurred equally into both membranous leaflets; if completed at E19 in the chicken, a redistribution of particles toward a higher P-face association was observed. In the rat, tight junction particles were redistributed toward a higher E-face association. These results are discussed in the context of blood-brain barrier induction, maintenance and regulation.     

Effect of delayed intervention with ACE-inhibitor therapy on myocyte hypertrophy and growth of the cardiac interstitium in the rat model of myocardial infarction

The effectiveness of angiotensin-converting enzyme (ACE)-inhibitor therapy in attenuating ventricular remodeling when initiated immediately following myocardial damage is clearly established. Less information, however, is available on the impact of late therapy on the remodeling process, especially its influence on the cellular components of these structural changes. The purpose of this study was to examine the effects of converting enzyme inhibitor therapy commenced 28 days following infarction in the rat on changes in cardiac myocyte dimension and the interstitium. At 28 days following infarction, myocyte cell length (153.9+/-7.3 v 131.1+/-5.9 micron, P=0.0002) and cell volume in the free wall of the left ventricle (38. 5+/-5.0 x 10(3) v31.4+/-3.1 x 10(3), P=0.009) had increased compared with sham-operated rats. Similar changes were noted in the septum and right ventricle. Captopril therapy administered between 28 and 56 days attenuated a further increase in cell length noted in an untreated group in the left ventricle (153.5+/-15.3 v 167.3+/-13.7 micron, P=0.02), right ventricle (153.8+/-20.5 v 173.8+/-2.3 micron, P=0.01) and septum (158.0+/-20.2 v 179.1+/-16.6 micron, P=0.004). There was an increase in hydroxyproline content in the right ventricle and a similar trend in the left ventricle in the untreated myocardial infarction groups. These changes were not altered by captopril therapy. In summary, even late therapy with captopril attenuates progressive myocyte remodeling, which may contribute to the ability of ACE-inhibitor therapy to slow progressive chamber enlargement following infarction.     

Reversible independent alterations in glucose transport and metabolism in cultured human cells deprived of glucose

During cell division in the Xenopus egg (diameter 1.25 mm) new cell membrane is formed in the furrow region (rate of growth approx 4-10(4) mum2/min). Freeze-fracture electron microscopy has produced the following data. Preexisting plasma membrane faces show a reversed polarity with respect to particle distribution, i.e. more particles are attached to the E-face (density 1600-2200 particles/mum2) than to the P-face (300 particles/mum2). A frequency histogram of 2331 measured intramembranous particles does not show a continuous range of sizes. The following sizes were very obvious: 95 A (12%), 125 A (30%) and 180 A (6%). At the tips of surface protrusions both the E- and the P- face are particle-free. Nascent cell membrane fracture faces are more difficult to obtain. The particle density is low (E-face 300-500 particles/mum2). Lowering the ambient temperature to 5 degrees C for approx. 5 mins does not change the normal particle pattern, but it improves the output in nascent membrane fracture faces. The fact that in the Xenopus egg preexisting and nascent membrane regions are continuous but nevertheless maintain their highly different particle densities is noteworthy. The freeze-fracture data are discussed in relation to, among other things, the known values of the specific resistances of these membrane regions.     

Collagen induces cytokine release by fetal platelets: implications in scarless healing

In previous studies the authors demonstrated that unlike adult platelets, fetal platelets respond poorly to collagen. When platelets make contact with the exposed collagen at the site of injury, the result is activation, aggregation, and degranulation with the release of cytokines and growth factors. This sequence of events is well characterized in adult wounds, which heal with an acute inflammatory response and dense scar formation. In sharp contrast, fetal dermal wounds heal without an acute inflammatory response and minimal scar formation. Therefore, the aim of this study was to test the hypothesis that collagen, abundant at the site of dermal injury, is a poor inducer of cytokine release by fetal platelets. This could explain, in part, the minimal inflammation accompanying fetal dermal wound healing. Platelet suspensions from six fetal Yorkshire swine at day 80 of gestation (term, 114 days) were exposed to either arachidonic acid, 0.5 mg/mL, collagen, 0.19 mg/mL, or saline. The release into plasma of transforming growth factor-beta (TGF-beta 1), and platelet-derived growth factor (PDGF)-AB effected by these agents was determined by enzyme-linked immunosorbent assays. Transmission electron microscopy (TEM) was used to correlate the biochemical findings with ultrastructural changes and showed that arachidonate-treated platelets were aggregated and devoid of granules. In contrast, collagen-treated platelets had undergone conformational changes but showed only a moderate change in the quantity and homogeneity of their secretory granules compared with saline-treated controls. There was a significant increase in TGF-beta 1 release into plasma after treatment with collagen (6.64 +/- 0.36 ng/mL) and arachidonate (7.64 +/- 0.77 ng/mL) compared with saline (4.74 +/- 0.36 ng/mL), P < .05. Likewise, PDGF-AB release was significantly higher after collagen (0.22 +/- 0.02 ng/mL) and arachidonate treatment (0.44 +/- 0.04 ng/mL) compared with saline (0.09 +/- 0.02 ng/ mL), P < .05. The authors conclude that fetal platelets actually do release cytokines in response to contact with collagen despite poor aggregation. Therefore, impaired aggregation to collagen cannot solely explain the minimal inflammation after fetal wounding.     

Self-healing juvenile cutaneous mucinosis in a patient with nephroblastoma

PURPOSE: Enhanced engraftment and reduced viral complications may be achieved in bone marrow transplantation (BMT) by limiting homologous transfusions. We report on limiting donor exposures before and after BMT in a newborn with severe combined immunodeficiency (SCID) using dedicated whole blood and plateletpheresis donors as well as a sterile connecting device (SCD). PATIENTS AND METHODS: A 1-day-old neonate was admitted for an allogeneic, human leukocyte antigen-disparate, T-cell-depleted BMT performed on day 43 of hospitalization. All transfused red blood cells (RBCs) and platelets were cytomegalovirus negative, and were irradiated and leukodepleted (via a Pall filter). Using the SCD, tubing above the filter was connected to the product bag, and the distal tubing was connected to a transfer pack for collection of the filtered product. Additional transfer packs were connected to the filtered product using the SCD to separate small aliquots as needed. RBC aliquots were irradiated individually before each transfusion. RESULTS: During a total of 134 days of hospitalization, only four donor exposures occurred. Eleven RBC transfusions (mean volume 46.4 +/- 12.6 ml) from three donors and five plateletpheresis transfusions (mean volume 74.2 +/- 7.5 ml) from one donor constituted all the patients' transfusion requirements. Evidence of engraftment was seen on day 18 post-BMT with an absolute neutrophil count sustained at > 500 cells/mm3. The last transfusion was received on day 35 post-BMT. CONCLUSIONS: Current blood transfusion technology enables patients undergoing bone marrow transplantation to have limited donor exposures. This practice should decrease viral complications without effecting bone marrow engraftment.     

Ineffective platelet production in thrombocytopenic human immunodeficiency virus-infected patients

Thrombocytopenia has been characterized in six patients infected with human immunodeficiency virus (HIV) with respect to the delivery of viable platelets into the peripheral circulation (peripheral platelet mass turnover), marrow megakaryocyte mass (product of megakaryocyte number and volume), megakaryocyte progenitor cells, circulating levels of endogenous thrombopoietin (TPO) and platelet TPO receptor number, and serum antiplatelet glycoprotein (GP) IIIa49-66 antibody (GPIIIa49-66Ab), an antibody associated with thrombocytopenia in HIV-infected patients. Peripheral platelet counts in these patients averaged 46 +/- 43 x 10(3)/microL (P = . 0001 compared to normal controls of 250 +/- 40x 10(3)/microL), and the mean platelet volume (MPV) was 10.5 +/- 2.0 fL (P > 0.3 compared with normal control of 9.5 +/- 1.7 fL). The mean life span of autologous 111In-platelets was 87 +/- 39 hours (P = .0001 compared with 232 +/- 38 hours in 20 normal controls), and immediate mean recovery of 111In-platelets injected into the systemic circulation was 33% +/- 16% (P = .0001 compared with 65% +/- 5% in 20 normal controls). The resultant mean peripheral platelet mass turnover was 3.8 +/- 1.5 x 10(5) fL/microL/d versus 3.8 +/- 0.4 x 10(5) fL/microL/d in 20 normal controls (P > .5). The mean endogenous TPO level was 596 +/- 471 pg/mL (P = .0001 compared with 95 +/- 6 pg/mL in 98 normal control subjects), and mean platelet TPO receptor number was 461 +/- 259 receptors/platelet (P = .05 compared with 207 +/- 99 receptors/platelet in nine normal controls). Antiplatelet GPIIIa49-66Ab levels in sera were uniformly increased in HIV thrombocytopenic patients (P < .001). In this cohort of thrombocytopenic HIV patients, marrow megakaryocyte number was increased to 30 +/- 15 x 10(6)/kg (P = .02 compared with 11 +/- 2.1 x 10(6)/kg in 20 normal controls), and marrow megakaryocyte volume was 32 +/- 0.9 x 10(3) fL (P = .05 compared with 28 +/- 4.5 x 10(3) fL in normal controls). Marrow megakaryocyte mass was expanded to 93 +/- 47 x 10(10) fL/kg (P = .007 compared with normal control of 31 +/- 5.3 x 10(10) fL/kg). Marrow megakaryocyte progenitor cells averaged 3.3 (range, 0.4 to 7.3) CFU-Meg/1,000 CD34(+) cells compared with 27 (range, 0.1 to 84) CFU-Meg/1,000 CD34(+) cells in seven normal subjects (P = .02). Thus, thrombocytopenia in these HIV patients was caused by a combination of shortening of platelet life span by two thirds and doubling of splenic platelet sequestration, coupled with ineffective delivery of viable platelets to the peripheral blood, despite a threefold TPO-driven expansion in marrow megakaryocyte mass. We postulate that this disparity between circulating platelet product and marrow platelet substrate results from direct impairment in platelet formation by HIV-infected marrow megakaryocytes.     

Blood pressure changes during short-term fluoxetine treatment

PURPOSE: To evaluate the potential diagnostic role of mediastinal sonography in patients with cystic fibrosis (CF), we screened the mediastinum of adult CF patients with and without signs of infection and healthy controls. METHODS: Fifty-four consecutive adult patients with CF and 53 healthy volunteers underwent high-resolution mediastinal sonography. The paratracheal region and aorticopulmonary window of each subject were examined for lymph nodes. Each patient was screened for clinical signs of infection. RESULTS: Lymph nodes were detectable in the mediastinum of 39 of 50 CF patients (78%); the mean total lymph node volume was 1.5 +/- 1.7 cm3. Lymph nodes were detectable in the mediastinum of 31 of 50 controls (62%); the mean total lymph node volume in this group was 0.3 +/- 0.3 cm3 (p < 0.001). In the 30 CF patients with signs of infection, the mean total lymph node volume was larger (2.0 +/- 1.8 cm3) than in the 20 CF patients without signs of infection (0.7 +/- 0.9 cm3; p = 0.002). CONCLUSIONS: These results indicate that lymph node volume determination by high-resolution mediastinal sonography may help assess inflammatory activity in patients with CF.     

Apolipoprotein(a) enhances platelet responses to the thrombin receptor-activating peptide SFLLRN

Elevated levels of lipoprotein(a) [Lp(a)] are correlated with an increased risk of atherosclerotic disease. We examined the effect of recombinant apolipoprotein(a) [r-apo(a)] and Lp(a) on responses of washed human platelets, prelabeled in the dense granules with [14C]serotonin and suspended in Tyrode's solution, to ADP and the thrombin receptor-activating peptide SFLLRN. No effect of the 17 kringle (K), 12K, or 6K r-apo(a) derivatives (at concentrations of 0.35 and 0.7 micromol/L) or Lp(a) (up to 0.1 micromol/L) on primary ADP-induced platelet aggregation was observed. In contrast, weak platelet responses stimulated by 7.5 micromol/L SFLLRN were significantly enhanced by the r-apo(a) derivatives; eg, 0.7 micromol/L 17K r-apo(a) increased aggregation from 15+/-4% to 58+/-6%, release of [14C]serotonin from 9+/-3% to 36+/-6%, and formation of thromboxane A2, measured as its stable metabolite thromboxane B2, from 7+/-1 to 29+/-5 ng/10(9) platelets (n=3; P<0.04 to 0.015). Significant enhancement of aggregation and release of granule contents was observed at a concentration of 17K r-apo(a) as low as 0.175 micromol/L. Purified Lp(a) (0.25 to 0.1 micromol/L) also enhanced SFLLRN-induced aggregation and release in a dose-dependent manner. Although plasminogen (0.7 and 1.5 micromol/L) and low density lipoprotein (0.025 to 0.1 micromol/L) both exhibited potentiating effects on SFLLRN-mediated platelet aggregation, the magnitude of the responses was less than that observed with either the r-apo(a) derivatives or Lp(a). The enhanced responses of platelets via the protease-activated receptor- thrombin receptor in the presence of Lp(a) may contribute to the increased risk of thromboembolic complications of atherosclerosis associated with this lipoprotein.     

Assessment of total body stores of vitamin A in Guatemalan elderly by the deuterated-retinol-dilution method

BACKGROUND: Deuterated retinol dilution (DRD) gives quantitative estimates of total body stores of vitamin A. OBJECTIVES: In elderly people, we studied 1) the time when an oral dose of deuterated vitamin A equilibrates with body stores, 2) whether serum ratios of deuterated to nondeuterated retinol (D:H) at 3 or 6 d postdosing predicted body stores, and 3) the ability of DRD to detect changes in the size of the body vitamin A pool. DESIGN: A 10-mg oral dose of [2H4]retinyl acetate was administered to 60-81-y-old Guatemalans (n = 47); percentage enrichment of serum retinol with deuterated retinol was determined at 1-3 time points per subject at 3, 6, 7, 14, 20, 21, and 54 d. In subjects from whom blood was obtained at 3 and 21 d (n = 15) and at 6 and 20 d (n = 9), total body stores were calculated by using the formula of Furr et al (Am J Clin Nutr 1989;49:713-6) with 21- or 20-d data and correlated with serum D:H at 3 or 6 d postdosing. Nine subjects received diets containing 982+/-20 microg RE (x+/-SEM) plus 800 microg RE as retinyl acetate supplements for 32 d. DRD, serum retinol, and relative dose response were used to assess vitamin A status before and after the intervention. RESULTS: Deuterated retinol equilibrated with the body pool by 20 d postdosing. Vitamin A supplementation for 32 d increased body stores, although unexplained exaggerated increases were seen in some subjects. An inverse linear relation was found between estimates of body stores and serum D:H at 3 d postdosing (r = -0.75, P = 0.002); at 6 d postdosing, the correlation was weaker. CONCLUSIONS: DRD can detect changes in total body stores of vitamin A, although factors affecting serum D:H need to be elucidated. Serum D:H 3 d postdosing might be used as an early indicator of total body stores of vitamin A, although a predictive equation will need to be developed.     

Co-existence of hepatitis A and adult Reye''s syndrome

The amyloid precursor protein is contained in platelet alpha granules and released with degranulation. Methods are described to control for amyloid precursor protein release from platelets during blood collection and processing. In normal subjects (n = 97; age range, 44-84 years), the average plasma level of amyloid precursor protein was 6.5 +/- 1.8 ng/ml.     

Ovarian sensitivity to exogenous gonadotrophins in phenobarbital treated unilaterally ovariectomized albino rats

To evaluate platelet activity in patients with non-insulin-dependent diabetes mellitus (NIDDM), we measured the mean platelet volume (MPV) and 24-hour urinary excretion of 11-dehydro-thromboxane B2 (11-dTXB2) and 6-keto-prostaglandin F1 alpha (6-kPGF1 alpha), stable metabolites of thromboxane A2 and prostacyclin, respectively. The MPV of the 103 subjects in the NIDDM group were 10.72 +/- 0.82 fl for males and 10.52 +/- 1.01 fl for females (mean +/- SD), significantly higher than those of normal controls (9.95 +/- 0.75 fl for males and 9.84 +/- 0.72 fl for females). The MPV of patients with NIDDM showed positive correlations with fasting plasma glucose level and HbA1c (r = 0.234, P < 0.05; r = 0.267, P < 0.01, respectively). The urinary excretion of 11-dTXB2 was greater in the NIDDM group (7.58 +/- 4.42 micrograms/day for males and 5.65 +/- 2.38 micrograms/day for females) than in the normal controls (4.61 +/- 2.31 and 3.83 +/- 1.60, respectively), suggesting that the synthesis of thromboxane A2 by platelets may be accelerated in vivo in patients with NIDDM. The urinary 6-kPGF1 alpha was not different between the NIDDM group and normal controls among the males, but was greater in the NIDDM group among the females. As MPV showed a positive correlation (r = 0.364, P < 0.05) with urinary excretion of 11-dTXB2, MPV may be related to platelet activity. These findings suggest that the platelets of patients with NIDDM may be in a hyperactive state.