A sequential culture approach to study osteoclast differentiation from nonadherent porcine bone marrow cells

BACKGROUND: This study reports relationships between suicidal behavior and its risk factors in prepubertal children and whole blood and platelet serotonin-related measures. METHODS: Seventy-five prepubertal psychiatric inpatients including 23 (30.7%) nonsuicidal, 32 (42.7%) with suicidal ideation, and 20 (26.6%) with a suicide attempt were compared to 35 normal prepubertal controls with regard to platelet serotonin content, serotonin-amplified platelet aggregation, and whole blood tryptophan. RESULTS: Mean whole blood tryptophan content was significantly lower among inpatient children with a recent suicide attempt than among normal controls or inpatients with suicidal ideation (F = 3.94, df = 3.54, p < or = .01). Inpatient children with a mood disorder had significantly higher platelet serotonin content than inpatients without a mood disorder (F = 3.86, df = 2.80, p < or = .03). Racial/ethnic differences were also observed for inpatients and normal controls, with whites having significantly lower levels of platelet serotonin (expressed as ng/mL blood or ng/10(9) platelets) than blacks or Latinos. Blacks had significantly higher levels of whole blood tryptophan than other racial/ethnic groups. CONCLUSIONS: The results suggest that whole blood tryptophan and platelet serotonin content should be studied for their predictive validity as risk factors for suicidal behavior in youth while controlling for racial/ethnic differences.     

Morphine reverses the inhibitory effects of repeated saline injections on peritoneal inflammation in mice

AIMS: The lipid composition of platelets and the function of these cells in patients with uremia were studied. METHODS: Fourteen patients and 14 normal volunteers were studied. Platelet lipids including phospholipids and cholesterol, as well as the platelet aggregation response to agonists, were studied. RESULTS: The amount of platelet phospholipids was decreased in patients compared to controls (338.0 +/- 79 vs. 511.6 +/- 125 nmol/10(9) cells; p < 0.001), while the percentage of the five main specimens of these compounds was normal. The content of platelet cholesterol in patients (97.8 +/- 17.0 microg/10(9) cells) was similar to that in controls (91.7 +/- 26.0 microg/10(9) cells). Consequently, the cholesterol:phospholipid ratio in uremic platelets was increased (0.75 +/- 0.1 vs. 0.46 +/- 0.1; p < 0.01). Although this feature is associated with hyperreactive platelets, the aggregation tests were defective for adenosin diphosphate (p < 0.01), arachidonic acid (p < 0.01), epinephrine (p < 0.01) and collagen (p < 0.001). This behavior is probably due to the multifactorial platelet defect described in uremia.     

Increased synthesis of prostaglandin-E-like material by platelets from patients with diabetes mellitus

We studied the effects of ADP, epinephrine, collagen and arachidonic acid on platelet production of immunoreactive prostaglandin-E-like material and aggregation in 17 subjects with diabetes mellitus and 21 matched controls. Plateletrich plasma obtained from patients synthesized significantly (P less than 0.05) greater quantities of the prostaglandin-E-like material after exposure to 1 muM ADP, 1, 2 and 5 muM epinephrine and 1 microgram per milliliter of collagen than platelet-rich plasma obtained from controls. That obtained from the diabetic patients was significantly more sensitive (P less than 0.001) to the aggregating effects of the prostaglandin precursor, arachidonic acid, in vitro as compared to controls. Diabetic platelet-rich plasma metabolized arachidonic acid (0.5 mM) to immunoreactive prostaglandin-E-like material at a significantly greater rate (P less than 0.05) and extent (P less than 0.001) than that of controls. Thus, platelets obtained from diabetic patients possess increased activity of the prostaglandin synthetase system, and this characteristic may be related to the increased platelet aggregation associated with the disease.     

Triphenyltin chloride induces glucose intolerance by the suppression of insulin release from hamster pancreatic beta-cells

An increased activity of phospholipase A2 has been observed in the plasma of patients with uremia. This enzyme converts phosphatidylcholine to lysophosphatidylcholine (LPC), an inhibitor of platelet aggregation. We measured the levels of plasma phospholipids including LPC, and platelet aggregation in 7 patients with uremia. Platelet response to agonists was defective, mainly with collagen (p < 0.001). The patients' levels of LPC in plasma were similar to those of controls (109.7 +/- 41.6 vs. 80.4 +/- 16.8 nmol/ml) and did not correlate with the platelet response to adenosine diphosphate (r = -0.51). The amount of phosphatidylcholine was increased with respect to normal plasma (1,041.0 +/- 201.8 vs. 760.8 +/- 142.7 nmol/ml, p < 0.01), while the levels of other phospholipids were normal. These results do not suggest a participation of plasma LPC in the genesis of the platelet defect observed in patients with uremia.     

Non-enzymatic production of nitric oxide (NO) from NO synthase inhibitors

In an attempt to evaluate the role of thrombopoietin (TPO) in the pathobiology of aplastic anaemia (AA), we have examined TPO levels in sera from 54 AA patients and 119 healthy controls. A total of 92 samples were collected from AA patients: 43 samples were harvested at diagnosis, 23 samples in the cytopenic period after treatment, and 26 samples when patients were in partial (n=10) or complete remission (n=16) following immunosuppressive treatment. TPO serum levels were assessed by a sandwich-antibody ELISA that utilized a polyclonal rabbit antiserum for both capture and signal. Serum samples from normal donors revealed a mean TPO level of 95.3 +/- 54.0 pg/ml (standard deviation). Mean TPO levels in AA sera collected at diagnosis and before onset of treatment were 2728 +/- 1074 pg/ml (P<0.001 compared to normal controls: mean platelet count at that time: 27x10(9)/l). TPO serum levels of AA patients in partial or complete remission after immunosuppressive treatment were significantly lower than TPO levels at diagnosis (P<0.001). However, despite normal platelet counts (mean 167x10(9)/l), TPO levels remained significantly elevated in complete remission (mean TPO 1009 +/- 590 pg/ml, P<0.001 compared to normal controls). There was a significant inverse correlation between serum TPO levels and platelet counts in AA patients who were not transfused for at least 2 weeks prior to sample collection (coefficient of correlation (r) = -0.70, P<0.0001). In summary, TPO levels were highly elevated in sera of patients with AA. Thus there is no evidence to suggest an impaired TPO response contributing to thrombocytopenia in AA. Thrombopoietin did not return to normal levels in remission, indicating a persisting haemopoietic defect in remission of AA. We hypothesize that elevated levels of TPO may be required to maintain normal or near normal platelet counts in remission of AA.     

Differential expression of platelet activation markers in aspirin-sensitive asthmatics and normal subjects

BACKGROUND: Activation of platelets and expression of adhesion molecules (e.g. CD62P and CD63) which mediate interactions between platelets and other cells may be important in the pathogenesis of aspirin-sensitive asthma. OBJECTIVE: To determine the expression of CD62P and CD63 on platelets from aspirin-sensitive asthmatic (ASA+), aspirin-tolerant asthmatic (ASA-) and normal subjects and to assess the modulatory effect of aspirin on platelet CD62P and CD63 expression following stimulation with either platelet-activating factor (PAF), arachidonic acid (AA) or collagen (COL). METHODS: Platelet-rich plasma was obtained from 10 ASA+, 10 ASA- and 10 normal control subjects, and expression of CD62P and CD63 was measured by flow cytometry. Platelets were stimulated with PAF (10, 80 nM), AA (0.1, 1 mM) or COL (80, 800 micrograms/mL) with or without aspirin (concentration range 0.4-4 mg/mL). RESULTS: In the absence of aspirin, CD62P expression induced by AA and COL was greater in ASA+ patients compared with control subjects (P < 0.001) while CD62P expression with PAF, AA and COL was reduced in ASA- when compared with ASA+ and control subjects (P < 0.001). CD63 expression with PAF and AA was reduced in both ASA+ and ASA- patients compared with control subjects (P < 0.001). Aspirin inhibited the expression of both CD62P and CD63 after agonist stimulation. Greater inhibition of CD62P expression was observed in ASA+ compared with ASA- patients (P < 0.001) and normal subjects (P < 0.05) while greater inhibition of CD63 expression was observed in normal subjects compared with both ASA+ and ASA- patients (P < 0.05). In ASA+ patients and normal subjects, stimulation with PAF and COL resulted in only one platelet population while in contrast with 1 mM AA two populations were observed. CONCLUSIONS: Enhanced AA- and collagen-induced platelet CD62P expression in ASA+ patients compared with normal subjects and greater inhibition by aspirin of CD62P expression in ASA+ may be relevant to the pathogenesis of this syndrome. Reduced expression of CD62P and CD63 in platelets of ASA- patients following stimulation with PAF and AA may also have implications for the role of platelets and these mediators in the pathogenesis of other forms of asthma.     

Lung epithelial permeability and bronchial responsiveness in subjects with stable asthma

Lung epithelial permeability of asthmatic patients has been reported to be similar or lower than that of healthy subjects and to be correlated or not to bronchial hyperresponsiveness. To clarify these discrepancies, we evaluated 99mTc-DTPA pulmonary clearance in a group of carefully selected asthmatic patients with mild, stable asthma (n = 13; seven women; mean age +/- SD = 27.69 +/- 6.63 years), and compared them with a group of healthy, nonsmoking subjects (n = 8; six women; mean age +/- SD = 24.38 +/- 5.15 years). Selection criteria for asthmatics were as follows: baseline FEV1 > or = 80% of predicted values, no bronchial infections, and/or no asthma attacks during 4 weeks prior to study and peak expiratory flow rate variability lower than 20%, over a period of 3 weeks. Patients controlled symptoms with beta 2-adrenergic drugs only, regularly or on demand. Mean baseline FEV1 (+/-SD) as percent of predicted was 102.38 +/- 13.97 and 112.88 +/- 18.36, respectively (p < 0.05). In the asthmatic group, bronchial responsiveness to methacholine (PC20 M FEV1) ranged between 0.55 and 28.5 mg/mL. Mean value (+/-SD) of DTPA clearance from lungs to blood (evaluated on the first 10 min out of 30 min of the curves) in the asthmatic group was not different from that of control group (68.31 +/- 21.46 and 69.5 +/- 15.73). In the asthmatic patients, there was no correlation between PC20 M values and DTPA T1/2 min of the whole lung, nor between PC20 M and inner and outer lung clearance zones. Moreover, both in asthmatics and healthy subjects, DTPA clearance of outer (alveolar) zones was significantly faster than that of inner (bronchial) zones (57.69 +/- 19.94 vs 102.08 +/- 38.19, p < 0.001, and 59.75 +/- 12.49 vs 103.5 +/- 31.86, p < 0.003, respectively). Our data show that DTPA clearance in patients with stable asthma is similar to that found in healthy subjects; it is not correlated to degree of bronchial responsiveness and occurs more rapidly in the outer zones than in the inner zones, both in asthmatic patients and in healthy subjects. Thus, to date, DTPA clearance index is not a valid tool for identifying and/or monitoring asthmatic patients.     

Platelet aggregation as a sign of septicemia in thermal injury. A prospective study

Serial measurements of coagulation activity, platelet counts, and platelet aggregation were done in patients with full-thickness burns involving 25% or more of body surface area to detect specific changes that might correlate with the onset of septicemia. Mean and maximal values for prothrombin time, partial thromboplastin time, thrombin time, activities of factor V and factor VIII, and concentrations of fibrinogen and fibrinogen-related antigens observed in the presence of bacterial septicemia did not differ significantly from those observed in the absence of septicemia. Mean platelet counts were significantly less with sepsis, but values in individual subjects were not indicative of the presence of septicemia. By contrast, platelet aggregation in response to adenosine diphosphate, epinephrine, and collagen always became severely abnormal with the onset of septicemia but not in the absence of sepsis.     

Small airways dimensions in asthma and in chronic obstructive pulmonary disease

The purpose of this study was to compare the dimensions of the peripheral airways in fatal asthma with those from patients with nonfatal asthma, mild COPD, and normal lung function. Lung specimens from eight individuals who had fatal asthmatic attacks were obtained at postmortem and compared with similar specimens from three asthmatic patients who died of an unrelated cause and four specimens obtained from known asthmatic patients who required lung resection for tumor. These 15 asthmatic lungs were also compared with lungs resected for peripheral neoplasms from 15 patients with normal airway function (FEV1, % of predicted > 85) and 15 patients with mild chronic airflow obstruction (FEV1, % of predicted < 85). All membranous airways with a long-short diameter ratio of 3:1 or less were examined. The smooth muscle and the tissue areas external and internal to the muscle layer were traced using a Bioquant BQ System 4. The same system was used to evaluate the fraction of the submucosa and adventitia taken up by blood vessels. The adventitial, submucosal, and muscle area of the asthmatic airways were greater than those of COPD and control (p < 0.01), and the muscle area was greater in COPD than in control lungs (p < 0.05). These parameters were also greater in the 8 patients with fatal asthma compared with the 7 patients with nonfatal asthma (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Spontaneous platelet activation and aggregation during obstructive sleep apnea and its response to therapy with nasal continuous positive airway pressure. A preliminary investigation

STUDY OBJECTIVE: To determine whether alterations of platelet reactivity occur during obstructive sleep apnea (OSA) and, if so, whether therapy with nasal-continuous positive airway pressure (N-CPAP) alters this reactivity. DESIGN: Patients with suspected moderate to severe OSA had blood drawn for spontaneous platelet aggregation (sAGG) and activation (sACT) measurements at hourly intervals during diagnostic polysomnography (PSG) and, in those with confirmed OSA, on a separate night during which N-CPAP was applied. SETTING: Tertiary care center sleep laboratory. PATIENTS: Six patients with OSA had matched blood samples drawn on both diagnostic and N-CPAP treatment nights. Five patients without confirmed OSA served as controls. INTERVENTIONS: N-CPAP was applied to those patients with OSA and pressures adjusted with goals of eliminating apneas; N-CPAP was then maintained through the night. MEASUREMENTS AND RESULTS: sACT and sAGG were measured using flow cytometric determination of P-selectin expression using a monoclonal antibody. Platelet aggregation was assessed by measuring the proportion of platelets larger than resting platelets by light scatter techniques. Mean values for sACT and sAGG were higher on the diagnostic night compared with treatment night (p = 0.001 and p = 0.003, analysis of variance, respectively). The mean baseline supine sACT compared with completion supine sACT for both diagnostic and N-CPAP nights also revealed significant differences (mean = 16.6 +/- 3.5% vs 36.9 +/- 7.5%, p = 0.04; and 11.9 +/- 3% vs 39.5 +/- 9.1%, p = 0.04). Platelet activation during sleep in five subjects without OSA resembles that found in patients with OSA during N-CPAP. CONCLUSIONS: Increased platelet sACT and sAGG occur during sleep in patients with OSA. This effect is greatly reduced by N-CPAP.     

Platelet aggregability in patients with a VVI pacemaker

Several studies have suggested an increased incidence of thromboembolic events in patients with VVI pacemaker (VVI patients); furthermore, other authors have demonstrated that a treatment with anticoagulants or antiplatelet drugs may be effective in reducing thromboembolic events, thus suggesting an increased formation of platelet thrombi in these patients. In this respect, platelet aggregability was investigated in ten VVI patients and ten age- and sex-matched subjects. beta-thromboglobulin (beta-Tg) and platelet factor 4 (PF4) plasma levels were determined as well as platelet aggregation induced by ADP, collagen, epinephrine, and arachidonic acid. Plasma beta-Tg levels were increased in the patient group (86 +/- 24 vs 24 +/- 13 ng/mL; P < 0.001) in presence of normal PF4 values (14 +/- 11 vs 13 +/- 6 ng/mL; NS). Aggregation curves showed abnormal values of maximal amplitude, slope, and lag time. In particular, maximal amplitude was significantly higher in VVI patients as compared with controls (ADP P < 0.01, collagen P < 0.001, adrenaline P < 0.01, arachidonic acid P < 0.05). These findings strongly suggest an increase of platelet activity in VVI patients.     

Who suffers most from leg ulceration?

This study examines health-related quality of life (HRQoL) in patients with leg ulceration and determines which patient groups are affected most by this condition. A cross-sectional study using the Nottingham Health Profile (NHP) and age/sex-matched normal scores in patients entering six clinical audit cycles was carried out. The 758 patients included in the study (mean age 74.6 years, 64% women) had been affected by leg ulceration for a median of 10.5 months (range 0.5 to 708). Patients produced significantly higher scores than age/sex-matched normal values for all domains of the NHP, indicating poorer HRQoL (all p < 0.001). Increasing age led to greater deficits in energy (p < 0.001) and mobility (p < 0.001) with greater social isolation (p = 0.044). Women experienced poorer energy, sleep patterns, mobility and emotional reactions (all p < 0.001), and increased physical pain and social isolation (p < 0.05) compared to men. However, higher scores may be expected for older women based on age/sex-matched normal values. After adjustment for age/sex-matched normal values, it was the younger patients who experienced a greater deficit in HRQoL over all domains of the NHP, with men scoring higher than women in the domains of bodily pain, sleep and social isolation (p < 0.001) and energy (p = 0.015). Leg ulceration has a major impact on patients' HRQoL as detected by the NHP. The excess in scores compared with age/sex-matched normal values indicate that it is younger male patients in whom ulceration makes a greater impact on HRQoL.     

Impaired platelet production of nitric oxide predicts presence of acute coronary syndromes

BACKGROUND: Thrombus formation within a coronary vessel is the acute precipitating event in most acute coronary syndromes. Recently, constitutive nitric oxide synthase (cNOS) has been identified in human platelets, and platelet-derived nitric oxide has been shown to inhibit platelet recruitment after aggregation. However, its role in regulating platelet responses under normal or pathologic conditions has not yet been elucidated. METHODS and RESULTS: We examined nitric oxide (NO) production by platelets isolated from 87 patients undergoing coronary angiography, 37 with stable angina and 50 with unstable angina or a myocardial infarction within 2 weeks. After stimulation with 5 micromol/L ADP, platelet aggregation and NO production were simultaneously measured with an NO-selective microelectrode adapted for use in a standard platelet aggregometer. Mean (+/-SEM) platelet-derived NO production was 1.78+/-0.36 pmol/10(8) and 0.26+/-0.05 pmol/10(8) platelets in coronary patients with stable angina and acute coronary syndromes, respectively (P=0. 0001). By logistic regression analysis, heparin treatment (odds ratio 6.6, CI 1.9 to 22.8, P=0.003), lower platelet-NO production (odds ratio 4.0, CI 1.3 to 11.5, P=0.01), and extent of atherosclerosis (odds ratio 1.5, CI 1.1 to 2.0, P=0.02) were independent predictors of an acute coronary syndrome. In the subset of patients with angiographic evidence of atherosclerosis (n=83), logistic regression demonstrated that platelet NO production (odds ratio 3.9, CI 1.3 to 11.1, P=0.01) and heparin treatment (odds ratio 6.4, CI 1.9 to 22.0, P=0.004) were independent predictors of an acute coronary syndrome, whereas extent of atherosclerosis was not. CONCLUSIONS: In summary, aggregating platelets from patients with acute coronary syndromes produce less NO. Since platelet aggregation and thrombus formation are implicated in unstable angina and myocardial infarction, impaired platelet-derived NO production may contribute to the development of acute coronary syndromes.     

Effects of surgical trauma of laparoscopic vs. open cholecystectomy

The effects of surgical trauma resulting from laparoscopic cholecystectomy and open cholecystectomy, were compared by assessing the postoperative acute phase alterations of selected plasma proteins, hormones and lymphocyte subpopulations in fifty-seven patients prior to elective cholecystectomy. Patients were prospectively randomized to undergo either laparoscopic cholecystectomy (n = 30) or open cholecystectomy (n = 27). Duration of operation and general anesthesia was similar in the two patient groups. The laparoscopic cholecystectomy patients had a shorter postoperative stay in hospital (3.1 (0.5) days vs. 7.1 (1.6) days; p < 0.001). In open cholecystectomy patients a significantly greater postoperative acute phase increase in plasma C-reactive protein (p < 0.001), cortisol (p < 0.05), and prolactin blood level (p < 0.001) was recorded. The postoperative acute phase decrease in the blood total-T-lymphocyte count (CD3 cells) and in the activated-lymphocyte count (OKDR cells) was significantly greater after open cholecystectomy (p < 0.05). These results, showing that acute phase responses are less marked after laparoscopic cholecystectomy than after open cholecystectomy, support the concept that the laparoscopic procedure is less traumatic.     

25-hydroxy vitamin D deficiency with reduction of intestinal calcium absorption and bone density in chronic alcoholism

Plasma levels of 25-hydroxycalciferol (25-OH-D), 47-calcium intestinal absorption, bone mineral content and the biologic parameters of phospho-calcium metabolism were studied in 30 chronic alcoholics, 15 with Laennec's cirrhosis (group A) and 15 without (group B). These patients were compared with 27 normal subjects. In group A, the mean 25-OH-D plasma level was 23.7 +/- SD 18.5 microgram/l and in group B 35.2 +/- SD 21.8 microgram/l. These mean levels were lower than those of the control group, which were 57.2 +/- SD 22.5 microgram/l (p less than 0.001). The mean value of the 47Ca intestinal absorption, measured as the percentage of the ingested dose per litre of plasma and multiplied by the body weight, was also significantly lower in group A, which was 140 +/- SD 47 (p less than 0.01), and in group B, which was 145 +/- SD 69 (p less than 0.05), compared with the normal subjects whose average was 182 +/- SD 45.6. Similarly, the total plasma calcium was low: 1.99 +/- SD 0.24 mmol/l in all the alcoholics, while that of the control group was 2.22 +/- SD 0.18 mmol/l (p less than 0.001). For the 30 chronic alcoholics there was a positive correlation between 25-OH-D and 47Ca intestinal absorption, (r = 0.484; p less than 0.004). This suggests that in chronic alcoholism the deficiency of 25-OH-D induces a diminution of the intestinal absorption of calcium which, in the long term, can result in bone demineralization evidenced in the patients studied by a bone mineral content lower than normal (p less than 0.001).     

Fibrinogen/fibrin degradation products in serum of patients with idiopathic thrombocytopenic purpura: elevated levels during severe thrombocytopenic phase of the disease

Sera from 23 patients with idiopathic thrombocytopenic purpura (ITP), 14 patients with aplastic anemia with severe thrombocytopenia and healthy control subjects were tested for the presence of fibrinogen/fibrin degradation products (FDP), using the tanned red cell hemagglutination inhibition immunoaassay. The concentrations of circulating FDP of ITP patients (mean 12.01 mug/ml) were significantly higher than those of the patients with aplastic anemia (mean 4.01 mug/ml, p less than 0.05) or normal controls (mean 3.10 mug/ml, p less than 0.001). The patients with untreated ITP with very low platelet counts had higher levels of FDP than those of the treated group (p less than 0.01). Serum FDP and a battery of other coagulation-fibrinolysis tests were serially carried out over a period of 10 weeks in two patients with ITP. The initially high FDP promptly decreased as circulating platelets increased in response to steroid in both patients, while plasma fibrinogen, euglobulin lysis time, prothrombin time and partial thromboplastin time remained essentially normal during the course of observation. The exact source of the increased serum FDP in ITP was not established, but a few possible mechanisms responsible for this abnormality were discussed.     

Evidence for altered platelet nitric oxide synthesis in essential hypertension

OBJECTIVES: To determine whether platelet aggregation to collagen was abnormal in patients with essential hypertension and whether nitric oxide donors and inhibitors of nitric oxide synthesis affect platelet aggregation differently in hypertensives compared with healthy controls. DESIGN: Platelet aggregation assays were conducted ex vivo from both hypertensive and normal subjects simultaneously. METHODS: Platelet aggregation in response to collagen was measured in platelet-rich plasma from 16 patients with untreated essential hypertension and 16 healthy volunteers matched for age, sex and smoking habits. The effect of sodium nitroprusside (a nitric oxide donor) and NG-monomethyl-L-arginine (L-NMMA), a specific nitric oxide synthase inhibitor, was studied. RESULTS: In healthy controls L-NMMA caused a marked increase in platelet aggregation, whereas in hypertensive patients a small inhibition of aggregation was seen. This was significantly different from the response seen in normal controls. No difference was seen in the aggregatory response to collagen between hypertensive patients and healthy controls. Sodium nitroprusside caused inhibition of aggregation in hypertensive patients and in controls, but there was no significant difference in the degree of inhibition between the two groups. CONCLUSIONS: We conclude that in platelets from hypertensive patients there is a markedly reduced sensitivity to L-NMMA, which could be explained by a reduction in nitric oxide synthesis.     

The young platelet population in children with cyanotic congenital heart disease

Some morphological, biochemical and functional parameters of platelet population in children with cyanotic congenital heart disease (CCHD) were studied by making comparisons of the normal platelet population in both CCHD patients and controls. The mean volume of the platelets from cyanotic patients was greater than from normals. The platelet size distribution curves demonstrated a shift towards larger than normal size in the case of CCHD. The mean protein content, as well as the mean PF3 content of platelets was increased in CCHD. Following addition of kaolin, PF3 release was more rapid and of shorter duration with platelets from CCHD patients as compared to normal platelets. They also released more PF3 than did normal platelets. After addition of ADP, collagen, or adrenalin, platelets of CCHD patients were more responsive than similarly treated platelets from normals. Platelets from CCHD showed an increased initial rate of aggregation and greater maximum aggregation. These data suggested that the platelet population of CCHD patients consists of larger, younger and functionally more active platelets than does the platelet population of normals.     

Plasma renin and aldosterone in thyroid diseases

The effect of thyroid hormones on the renin-angiotensin-aldosterone system has not been fully resolved. Highly specific immunoassays for measurement of renin, aldosterone, free T4 (fT4), free T3 (fT3) and ultrasensitive TSH enables a direct and more accurate measurement of these hormones. We investigated the relationship between plasma renin, aldosterone and thyroid hormones in the basal state and after intravenous frusemide. This is a cross-sectional study involving 37 patients with thyrotoxicosis, 42 rendered euthyroid with normal fT4, fT3 and TSH levels, 17 with euthyroid levels of fT4 and fT3 but suppressed TSH, and 11 with hypothyroidism. Basal plasma renin was significantly higher in thyrotoxicosis (63.4 +/- 9.8 microU/ml, mean +/- SEM) compared to euthyroid (32.7 +/- 4.4 microU/ml) and hypothyroid (26.7 +/- 9.8 microU/ml). Basal plasma renin for euthyroid with suppressed TSH (41.0 +/- 7.4 microU/ml) was significantly higher than hypothyroid (p = 0.02). Basal plasma aldosterones were not significantly different except for suppressed TSH (157.7 +/- 13 pg/ml), which was higher than normal (109.9 +/- 10.4 pg/ml; p = 0.04). Following frusemide, plasma renin and aldosterone were significantly increased in all groups. Plasma renin was highly correlated to fT3 (r = 0.405, p < 0.001), total T3 (r = 0.359, p < 0.001), fT4 (r = 0.331, p < 0.001) and TSH (r = 0.300, p < 0.001) in the basal state, but less to total T4 (r = 0.248, p < 0.01). Plasma renin correlated poorly to serum aldosterone (r = 0.212, p < 0.03). This study clearly showed that regulation of renin was mainly influenced by fT3, and that aldosterone response to frusemide was blunted in thyrotoxicosis despite normal electrolytes.     

Milk production of Holstein heifers fed either alfalfa or corn silage diets at two rates of daily gain

OBJECTIVES: L-arginine exerts anti-atherosclerotic effects in hypercholesterolaemic rabbits via modulating endogenous NO production. We investigated whether L-arginine inhibits thromboxane formation in vivo and platelet aggregation ex vivo in this animal model. METHODS: The urinary excretion rates of 2,3-dinor-6-keto-PGF1 alpha (major urinary metabolite of PGI2) and 2,3-dinor-TXB2 (major urinary metabolite of thromboxane A2) were used as indicators of platelet-endothelial cell interactions in vivo. Rabbits were fed 1% cholesterol (Cholesterol group, N = 8), 1% cholesterol plus 2.25% L-arginine (Cholesterol + L-arginine, N = 8), or normal rabbit chow (Control, N = 4) for 12 weeks. Urine samples were collected in weekly intervals. At the end of the study period platelet aggregation ex vivo and endothelium-dependent and -independent vascular function of isolated aortic rings in vitro was assessed. RESULTS: Urinary 2,3-dinor-TXB2 excretion significantly increased in the cholesterol group (p < 0.05), and endogenous NO formation (measured as urinary nitrate excretion) decreased (p < 0.05). Both parameters were significantly correlated with each other (R = 0.48, p < 0.01). L-arginine partly restored urinary nitrate excretion and significantly reduced TXA2 production to values even below those in the control group (p < 0.001). Urinary 2,3-dinor-6-keto-PGF1 alpha excretion increased in early hypercholesterolaemia and returned to control values in the second half of the study period. The early increase in urinary 2,3-dinor-6-keto-PGF1 alpha excretion was attenuated by L-arginine. Platelet aggregation was significantly enhanced in cholesterol-fed rabbits and attenuated by dietary L-arginine. L-arginine also improved the impaired endothelium-dependent relaxations to ADP, and normalized the vasoconstrictor effects of 5-HT in isolated aortic rings. CONCLUSIONS: Cholesterol-feeding enhances platelet aggregation and TXA2 formation, and stimulates platelet-endothelial cell interaction in rabbits. These effects are probably due to impaired NO elaboration, as indicated by decreased urinary nitrate excretion. Chronic dietary supplementation with L-arginine elevates systemic NO elaboration and significantly increases the PGI2/TXA2 ratio. It thus beneficially influences the homeostasis between vasodilator and vasoconstrictor prostanoids in vivo.