Plasma endothelin-1 levels during transient acute myocardial ischaemia in men: effects of coronary revascularization

The endothelium-derived peptide endothelin-1 (ET-1) was evaluated in 14 male patients [mean age 52.74 years (SEM 1.10)] affected by coronary artery disease during a bicycle electrocardiographic stress test and dipyridamole echocardiogram. Both tests were performed before and after coronary revascularization. Fourteen healthy male subjects served as controls [mean age 53.21 years (SEM 1.63)]. Baseline plasma endothelin-1 levels were higher ( P  < 0^.0001) in ischaemic patients [1^.81 pg mL⁻¹ (0^.15, n  = 14)] than in control subjects [0^.61 pg mL⁻¹ (0^.03, n  = 14)], but did not increase with exercise in both groups. Similar results were obtained with dipyridamole infusion. Endothelin-1 levels significantly decreased after coronary revascularization [before: mean 1^.81 pg mL⁻¹ (SEM 0^.15, n  = 14); after: mean 1^.16 pg mL⁻¹ (SEM 0^.11), P  < 0^.002], without changes in the peptide response to both tests. In conclusion, elevated plasma endothelin-1 concentrations were found in patients with stable angina compared with non-ischaemic subjects. No changes were observed during exercise or dipyridamole infusion in both groups. Coronary revascularization was followed by a significant decrease in plasma endothelin-1 levels.     

Inhibition of paracrine angiotensin-converting enzyme in vivo: effects on interstitial glucose and lactate concentrations in human skeletal muscle

Microdialysis was used to selectively assess the effect of the paracrine renin–angiotensin system (RAS) on interstitial glucose and lactate concentration profiles in skeletal muscle of healthy volunteers ( n  = 8) during basal and insulin-stimulated conditions. Paracrine RAS was selectively inhibited by local retrodialysis with enalaprilate. Under basal conditions, local administration of enalaprilate (2 μg mL⁻¹) increased interstitial dialysate glucose concentration from 0.71 ± 0.14 mmol L⁻¹ to 0.84 ± 0.14 mmol L⁻¹ and decreased the serum interstitial gradient (SIG_glu) compared with baseline ( P  < 0.02). Under clamp conditions, enalaprilate, even at the lowest concentration (0.02 μg mL⁻¹), increased interstitial dialysate glucose concentration from 0.77 ± 0.11 mmol L⁻¹ to 1.02 ± 0.09 mmol L⁻¹ and decreased SIG_glu compared with baseline ( P  < 0.01). Interstitial lactate concentrations slightly increased during basal as well as during clamp conditions ( P  < 0.05 vs. baseline). Selective inhibition of paracrine muscle angiotensin-converting enzyme (ACE) increases interstitial glucose and lactate concentrations and decreases SIG_glu in muscle by facilitating transcapillary glucose transport. This effect is more pronounced during hyperinsulinaemia and may be of clinical relevance in diabetic patients treated with therapeutic doses of enalapril.     

Racial differences in endotoxin-induced tissue factor-triggered coagulation

Summary.  Background: Racial differences in coagulation are poorly understood. While some studies suggest a 'prothrombotic' coagulation profile in blacks compared with whites, others report an increased bleeding risk for blacks in various clinical settings. Moreover, preclinical data suggest a link between the Duffy antigen (= DARC, Duffy antigen receptor of chemokines) and coagulation. Objectives: Based on our previous research in Duffy antigen negative Africans, we hypothesized that Africans have an attenuated procoagulant response compared with Caucasians in a model of lipopolysaccharide (LPS)-induced, tissue factor (TF)-triggered coagulation activation. Patients/methods: Healthy male volunteers (16 Duffy-negative Africans, 16 Duffy-positive Caucasians) received 2 ng kg⁻¹ LPS, and outcome parameters were measured using enzyme immunoassays and real-time polymerase chain reaction (RT-PCR, Taqman). Results: LPS increased microparticle (MP)-associated TF procoagulant activity (PCA) less in Africans than Caucasians. Africans had reduced in vivo thrombin formation compared with Caucasians: they generated less thrombin–antithrombin (TAT) complexes (10.4 pg mL⁻¹ vs. 23.0 pg mL⁻¹, P  < 0.0001) and less prothrombin fragments (F₁₊₂) (337 pmol mL⁻¹ vs. 819 pmol mL⁻¹, P  < 0.0001). Consistently, Africans also had decreased fibrin formation ( d -dimer: 0.3 pg mL⁻¹ vs. 0.5 pg mL⁻¹, P  = 0.02). Conclusion: Duffy-negative subjects of African descent have a markedly reduced procoagulant response in a model of LPS-induced, TF-triggered coagulation activation compared with Duffy-positive healthy Caucasians.     

Plasminogen activator inhibitor-1 predicts coronary in-stent restenosis of drug-eluting stents

Background : We tested the hypothesis that plasma levels of plasminogen activator inhibitor-1 (PAI-1) are influenced by percutaneous coronary intervention (PCI) with the implantation of drug eluting stents (DES) and are able to predict the occurrence of in-stent restenosis (ISR). Methods and results : PAI-1 active antigen plasma levels were determined in 75 patients before and 24 h after PCI with DES implantation. Patients with ISR after six to eight months (16%) showed significantly lower PAI-1 plasma levels before PCI (ISR, 11.7 ± 8.1 ng mL⁻¹; non-ISR, 22.8 ± 18.8 ng mL⁻¹; P  < 0.05). PAI-1 levels in the lowest tertile were associated with a 9.5-fold increased risk of ISR, independent of clinical risk factors, angiographic or procedural characteristics, compared to the highest tertile ( P  <   0.05). The induced change of PAI-1 active antigen 24 h after PCI was significantly higher in patients with ISR (ISR, +5.6 ± 8.0 ng mL⁻¹; non-ISR, −3.2 ± 12.1 ng mL⁻¹; P  <   0.05) with positive correlation to late lumen loss ( r  =   0.30; P  <   0.05). Conclusions : ISR after DES implantation is significantly related to plasma levels of PAI-1 active antigen before and after PCI. If confirmed by larger multicenter studies, the determination of PAI-1 plasma levels might be clinically helpful in the identification of patients at high risk of developing of ISR, even after DES implantation.     

Cisplatin-induced renal effects and thromboxane A2 receptor blockade

The aim of this study was to evaluate the renal protective effect of linotroban, a thromboxane A₂ receptor antagonist, in 25 patients with malignant tumours scheduled for cisplatin therapy. Cisplatin was administered 1 h after the start of a 24-h continuous infusion of linotroban or placebo. Glomerular filtration rate and effective renal plasma flow were measured. Infusions of cisplatin decreased glomerular filtration rate by 17 ± 25 mL min⁻¹ ( P  = 0.049 vs. baseline) and effective renal plasma flow by 94 ± 150 mL min⁻¹ ( P  = 0.049 vs. baseline) in the placebo group. In the linotroban group a decrease in glomerular filtration rate by 11 ± 18 mL min⁻¹ ( P  = 0.050 vs. baseline) and in effective renal plasma flow by 26 ± 63 mL min⁻¹ ( P  = 0.2 vs. baseline) was noted. However, no difference was noted between groups in response to treatment. Our findings indicate that linotroban may not be useful for prevention of cisplatin's acute nephrotoxic effects.     

Different effects of oral contraceptives containing different progestogens on protein S and tissue factor pathway inhibitor

Summary.  Background:  Oral contraceptives (OC) containing different types of progestogens induce different sensitivities to activated protein C (APC) measured with the thrombin generation-based APC-resistance test. These differences in APC resistance may be the biological explanation for the differences in thrombotic risk of the various pills. The mechanistic basis of APC resistance observed in OC users is unknown. Our objective was to study the effect of OC on the two main determinants of the APC-resistance test, free protein S and free tissue factor pathway inhibitor (TFPI). Patients/methods:  We measured free protein S and free TFPI in 156 users of various types of OC. Results:  Users of desogestrel-containing OC, known to double the risk of thrombosis compared with levonorgestrel-containing OC, had lower free protein S (24 vs. 33 U dL⁻¹) and TFPI free antigen (2.9 vs. 3.6 ng mL⁻¹) levels than users of OC containing levonorgestrel. Women using cyproterone acetate-containing OC, known to confer a high thrombotic risk, had the lowest free protein S (19 U dL⁻¹) and free TPFI antigen (2.5 ng mL⁻¹) levels. Users of OC containing drospirenone had lower free protein S (23 U dL⁻¹) and TFPI antigen levels (3.2 ng mL⁻¹) than users of levonorgestrel-containing OC. Low free protein S and low free TFPI antigen levels were associated with an increased resistance to APC, an established risk factor for thrombosis. Conclusions:  This study observed that the differences in APC resistance induced by OC containing different progestogens can at least in part be explained by different effects of OC on free protein S and TFPI.     

Serum levels of parathyroid hormone are related to the mortality and severity of illness in patients in the emergency department

Hypocalcaemia is a common finding in intensive care patients. In addition, raised levels of parathyroid hormone (PTH) have been described. The explanation and clinical importance of these findings are yet to be revealed. To investigate the occurrence of hypocalcaemia and elevated PTH levels and their relationship to morality and the severity of disease, serum levels of PTH, ionized calcium (Ca²⁺) and the cytokines interleukin 6 (IL-6) and tumour necrosis factor alpha (TNF-α) were measured on arrival in the emergency department in a broad spectrum of 140 acutely ill patients patients suffering from common diseases such as stroke, acute abdominal disorders, obstructive lung diseases, heart failure, acute myocardial infarction, angina pectoris, trauma and infectious diseases. A score (APACHE II) was calculated to assess the severity of disease. Elevated PTH levels (> 55 pg mL⁻¹) were seen in 16% of the patients, being most frequent in patients with myocardial infarction (28%) and congestive heart failure (42%). The levels were significantly correlated with the APACHE II score ( r  = 0.48, P  < 0.0001) and with the length of stay in hospital ( r  = 0.26, P  < 0.002). PTH was also significantly ( P  < 0.03) elevated in non-survivors compared with survivors and was found to be a stronger predictor of mortality ( P  < 0.01) than the APACHE II score ( P  < 0.02) in Cox's proportional hazard analysis. No close relationships were found between the cytokine levels and the indices of calcium metabolism. In conclusion, a rise in serum levels of PTH was common and related to the severity of disease and mortality in a mixed emergency department population.     

Defective interferon-gamma production by T-lymphocytes from patients with acute brucellosis

The authors investigated the production of interleukin-2 (IL-2) and interferon-gamma (IFN-γ) by phytohaemagglutinin (PHA)-stimulated T-lymphocytes from 21 untreated patients with acute brucellosis. PHA-stimulated T-lymphocytes from acute brucellosis patients showed normal IL-2 production but defective IFN-γ production (brucellosis patients 531 ± 103 pg mL⁻¹ vs. healthy controls 1024 ± 212 pg mL⁻¹) after 72 h of culture. This altered pattern of IL-2 and IFN-γ production by T-lymphocytes was observed in seven brucellosis patients whose T-lymphocytes exhibited a normal proliferative response to PHA (61 612 ± 18 422 cpm) as well as in the 14 patients with a defective T-lymphocyte proliferative response to the PHA after 5 days of culture (19 479 ± 4409 cpm). After antibiotic therapy, production of the two lymphokines by the PHA-stimulated T-lymphocytes from acute brucellosis patients was similar to that of T-lymphocytes from healthy control subjects. The authors conclude that PHA-stimulated T-lymphocytes from untreated patients with acute brucellosis have defective INF-γ production but normal IL-2 production.     

Cytokine profiles in bronchoalveolar lavage fluid and blood in HIV-seropositive patients with Pneumocystis carinii pneumonia

Concentrations and ex vivo production of interleukin 1β (IL-1), tumour necrosis α (TNF), interleukin 6 (IL-6), interleukin-1 receptor antagonist (IL-1RA) and TNF soluble receptors (sTNF-receptors, P55 and P75) were measured in bronchoalveolar lavage (BAL) fluid and blood in 23 HIV-seropositive (HIV+) patients with Pneumocystis carinii pneumonia (PCP) and compared with values found in healthy HIV-seronegative (HIV−) controls and asymptomatic HIV+ subjects. Concentrations of the proinflammatory cytokine IL-1β were increased in BAL fluid of HIV+ patients with PCP (184 ± 47 pg mL⁻¹) compared with undetectable levels in healthy control subjects ( P  = 0.0001). In plasma of these patients higher concentrations of the anti-inflammatory cytokine IL-1RA were found during acute PCP than after recovery (2.1 ± 0.7 vs. 0.5 ± 0.2 ng mL⁻¹, P  = 0.01). No correlations could be found between cytokine concentrations and clinical severity of the infection. Corticosteroid treatment did not influence cytokine concentrations in BAL or blood, nor did it suppress the production in alveolar cells. In whole-blood cultures, however, lipopolysaccharide (LPS)-stimulated production was significantly suppressed for IL-1 (1.3 vs. 5.5 ng mL⁻¹, P  = 0.009) and for IL-6 (0.6 vs. 2.5 ng mL⁻¹, P  = 0.01). The overall data show that in HIV+ patients with PCP (similar to what we had found previously in HIV− patients with PCP) proinflammatory cytokines are more prominently present in BAL, whereas anti-inflammatory reaction is predominant in the circulation.     

Effects of glucagon-like peptide 1 (7–36 amide) on whole-body protein metabolism in healthy man

The incretin glucagon-like peptide 1 (GLP-1) shows glucose-dependent insulinotropic activity and may exert anabolic effects. Whole-body protein metabolism was assessed by measuring [1-¹³C]-leucine kinetics in 13 healthy volunteers during hyperglycaemic clamping with or without pancreatic clamping (somatostatin infusion) in order to differentiate between insulin-mediated and direct GLP-1 effects. During intact pancreatic secretion leucine flux and leucine oxidation rate as parameters of whole-body protein breakdown decreased markedly after 180 min of synthetic GLP-1 infusion (GLP-1 vs. placebo: P  < 0.003). Indirect calorimetry showed an increase in energy expenditure and CO₂ production during GLP-1 administration ( P  < 0.0005). Plasma insulin increased after 3 h of GLP-1 infusion to 1486 ± 145 pmol L⁻¹ vs. 185 ± 12 pmol L⁻¹ for saline ( P  < 0.0001). When plasma insulin levels were kept constant (GLP-1 vs. saline, NS) during pancreatic clamping, GLP-1 effects on both protein metabolism and energy expenditure were abolished. Thus, GLP-1 infusion in man exerts protein anticatabolic and thermic effects, which are mediated by GLP-1-induced stimulation of insulin secretion.     

Inhibited neutrophil functions in patients treated with nifedipine but not with verapamil or diltiazem

Neutrophil functions were studied in patients receiving calcium channel blockers: nifedipine, diltiazem or verapamil. Neutrophils from patients treated with nifedipine showed a significantly lower superoxide generation stimulated by phorbol myristate acetate (PMA) (50 ng mL⁻¹), opsonized zymosan (1 mg mL⁻¹) or formyl-methionyl-leucyl-phenylalanine (FMLP) (10⁻⁷  m ), whereas superoxide generation by neutrophils of patients receiving diltiazem or verapamil showed only a slight and insignificant reduction compared with controls. Similarly, chemotaxis towards 10⁻⁷  m FMLP and phagocytosis were significantly lower in patients receiving nifedipine compared with controls and were only slightly reduced in patients receiving diltiazem or verapamil. Nifedipine was the most efficient drug in inhibiting the rise in intracellular calcium ion concentration ([Ca²⁺]_i) when added in vitro and in neutrophils of patients receiving this drug, whereas verapamil had no significant effect. The correlation between the inhibitory effect of nifedipine on neutrophil function and the elevation of [Ca²⁺]_i suggests that nifedipine inhibits neutrophil functions through its effect on [Ca²⁺]_i. However, it is not the sole mechanism as superoxide generation induced by PMA, an agent that does not induce a rise in [Ca²⁺]_i, is also inhibited. The unique effect of nifedipine in reducing neutrophil functions in vivo suggests its clinical implications concerning response to acute ischaemic myocardial events.     

Glycaemic control and in vivo non-oxidative Maillard reaction: urinary excretion of pyrraline in diabetes patients

The presence of pyrraline in human urine has recently been described. Using reversed-phase high-performance liquid chromatography, we measured urinary pyrraline in 45 insulin-treated diabetic patients with preserved renal function and in 30 age- and sex-matched healthy subjects. The relationship between urinary pyrraline and metabolic control parameters in the diabetic population (glycaemia, fructosamine, haemoglobin Al_c, and 1-year mean haemoglobin A1_c) was evaluated. The mean urinary level of pyrraline in diabetic patients with poor glycaemic control (HbA_1c > 9.5%) was higher than that in healthy subjects (1.12 ± 0.35 vs. 0.75 ± 0.2 μmol mmol⁻¹ creatinine, P  < 0.04), whereas in patients with good to moderate glycaemic control (HbA1_c < 9.5) it was slightly but not significantly higher than in healthy subjects (0.80 ± 0.3 μmol mmol⁻¹ creatinine vs. 0.75 ± 0.2 μmol mmol⁻¹ creatinine). There is a significant correlation between urinary pyrraline level and glycaemia ( P  < 0.008), haemoglobin A1_c ( P  < 0.01) and 1-year mean haemoglobin A1_c values ( P  < 0.007), but not with fructosamine. The results of the present work prove, for the first time, that glycaemic status influences circulating levels of advanced Maillard reaction products.     

Relationship between lipoprotein(a) phenotypes and albumin excretion rate in non-insulin-dependent diabetes mellitus: protective effect of ‘null’ phenotype?

The possible association between lipoprotein(a) [Lp(a)] and albumin excretion rate (AER) is a topic that generates conflicting views. In addition, Lp(a) phenotypes have not previously been considered as factors influencing AER. In order to clarify this issue, we studied 70 non-insulin-dependent diabetes mellitus (NIDDM) patients without clinically detectable macroangiopathy, 27 with microalbuminuria and 43 without it. Both groups were matched for the known variables that could influence AER and serum Lp(a) levels. Lp(a) was determined by enzyme-linked immunosorbent assay (ELISA), and Lp(a) phenotypes were assessed by electrophoresis followed by immunoblotting. Lp(a) phenotypes were grouped as follows: 'small' (F, S1 and S2), 'big' (S3 and S4) and 'null'. The NIDDM patients with microalbuminuria presented higher serum Lp(a) concentrations than the patients without it [15.7 mg dL⁻¹ (95% CI 0.5–36.5) vs. 4.5 mg dL⁻¹ (95% CI 0.1–18.5); P  < 0.001] and a direct correlation between Lp(a) and AER was observed ( r  = 0.34; P  < 0.01). AER was significantly different when Lp(a) phenotypes were considered ['small': median 19 μg min⁻¹ (range 1–195); 'big': median 9.5 μg min⁻¹ (range 1–186); 'null': 4 μg min⁻¹ (range 1–9); P  = 0.04]. None of the NIDDM patients with a 'null' phenotype showed an AER of > 10 μg min⁻¹. In conclusion, this case–control study provides evidence that microalbuminuria is associated with high serum Lp(a) in NIDDM without clinically detectable macroangiopathy. Furthermore, NIDDM patients with a 'null' phenotype could be considered at low risk for the development of microalbuminuria.     

Low-density lipoprotein metabolism and its association to plasma lipoprotein(a) in the nephrotic syndrome

Patients with nephrotic syndrome have multiple abnormalities of lipoprotein metabolism, but the cause and exact nature of these abnormalities have not been established. In the present study we have determined the kinetics of plasma low-density lipoprotein (LDL) apoB in seven nephrotic patients demonstrating an elevated LDL apoB production rate (25.7 ± 6.4 vs. 13.1 ± 0.3 mg kg^–1 day^–1; P  < 0.001) but a normal LDL apoB fractional catabolic rate (FCR) (0.31 ± 0.04 vs. 0.33 ± 0.008 pools day^–1; NS) compared with 41 healthy control subjects. However, two out of the seven patients had a markedly low LDL apoB-FCR. Serum albumin was inversely correlated with the LDL apoB production rate ( R  = –0.82; P  < 0.05). Plasma lipoprotien (a) [Lp(a)] levels were significantly ( P  < 0.001) increased in the nephrotic patients compared with control subjects. Significant correlations were observed between log Lp(a) and LDL apoB production rate ( R  = 0.90; P  < 0.01), VLDL-cholesterol ( R  = 0.95; P  < 0.001) and VLDL-triglycerides ( R  = 0.80; P  < 0.05) respectively. In summary, the present study suggests that nephrotic hyperlipidaemia may be caused by at least two independent mechanisms. The elevated LDL apoB production rate is highly correlated with the prevailing levels of serum albumin, whereas some nephrotic patients seem to have a decreased LDL apoB clearance, suggesting impaired LDL receptor-mediated clearance. The present results also suggest that the elevated plasma Lp(a) levels in nephrosis are related to an increased hepatic synthesis rather than a decreased catabolism of lipoproteins.     

Apolipoprotein E2 (Arg-136→Cys), a variant of apolipoprotein E associated with late-onset dominance of type III hyperlipoproteinaemia

Type III hyperlipoproteinaemia (HLP) is usually associated with homozygosity for apolipoprotein (apo) E2 (Arg-158→Cys). We identified a 46-year-old white female with severe hyperlipidaemia and the heterozygous apo E3/2* phenotype. Typical clinical characteristics of type III HLP, i.e. palmar xanthomas (orange–yellowish discolorations of the palmar creases) and tuberoeruptive xanthomas, were present in the patient. Without therapy the patient's serum triglycerides (1.098 mg dL⁻¹), cholesterol (546 mg dL^–1), very low-density lipoprotein (VLDL) cholesterol (372 mg dL⁻¹) and the apo E concentration (25.0 mg dL⁻¹) were distinctly elevated as well as her VLDL cholesterol to serum triglyceride (TG) ratio at 0.34 (normal ratio about 0.2). Direct sequencing of polymerase chain reaction (PCR)-amplified segments of the apo ε gene identified a thymine for cytosine (C→T) exchange in the first base of codon 136 that is predictive for a Cys ( T GC) for Arg ( C GC) substitution in the encoded amino acid sequence. Two children, an 18-year-old female with the heterozygous apo E4/2* phenotype, a 25-year-old female with the heterozygous apo E3/2* phenotype and the 73-year-old father of the proband with the heterozygous apo E3/2* phenotype are also carriers of the rare mutant. The father has severe atherosclerosis and lipid values compatible with the diagnosis of type III HLP. The affected children have hyper/dyslipidaemia but as yet no clinical expression of the disease. We propose that in the analysed family this rare apo E2 (Arg-136→Cys) variant is associated with late-onset dominance of type III HLP.     

Coagulation factor XII (FXII) activity, activated FXII, distribution of FXII C46T gene polymorphism and coronary risk

Summary.  Background:  Whether factor XII (FXII) activity, its 46C>T polymorphism and activated FXII (FXIIa) are associated with coronary heart disease (CHD) remains to be determined. Methods:  FXII, FXIIa and the FXII 46C>T polymorphism were determined in a hospital-based cohort of 2615 patients undergoing coronary angiography. Results:  Fifty-seven per cent of the participants were identified as wild-type (46CC), 38% as heterozygous (46CT) and 5% as homozygous (46TT) for FXII 46C>T. FXII and FXIIa levels were significantly lower in carriers of the T-allele: 132 (97–151) U dL⁻¹ FXII in 46CC, 87 (77–99) U dL⁻¹ FXII in 46CT and 53 (42–67) U dL⁻¹ FXII in 46TT carriers ( P  <   0.001), and 2.8 (2.3–3.5) μg L⁻¹ FXIIa in CC, 2.1 (1.6–2.6) μg L⁻¹ FXIIa in CT and 1.2 (0.9–1.5) μg L⁻¹ FXIIa in TT carriers ( P  <   0.001; medians, lower and upper quartiles). Patients with stable CHD ( n  =   935), a history of myocardial infarction ( n  =   785) or who were suffering from acute coronary syndromes (ACS; n  =   323) had significantly lower FXII levels than controls ( n  =   572). The differences remained statistically significant after adjustments for age, sex, diabetes mellitus, smoking, hypercholesterolemia and hypertension. Significantly reduced FXIIa levels in ACS patients lost significance once adjusted for covariates. FXII genotype was not associated with any clinical phenotype. Conclusion:  Lower FXII activity represents an independent risk for CHD and ACS. This is not the case for FXIIa levels or the FXII 46C>T variation.     

Responses of atrial natriuretic peptide and brain natriuretic peptide to exercise in patients with chronic heart failure and normal control subjects

Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are known to be elevated in patients with chronic heart failure at rest. While it is known that during exercise the circulating level of ANP increases in patients with heart failure, the response of BNP to exercise in these patients relative to control subjects is unclear. Ten patients with stable chronic heart failure and 10 normal control subjects performed symptom-limited exercise with respired gas analysis. All patients had depressed left ventricular ejection fractions (LVEF). Patients had lower peak oxygen consumption P V ˙ O ₂) than the control group [median (range) 1.18 (0.98–1.76) vs. 1.94 (1.53–2.31) L min⁻¹; P  < 0.001]. Circulating plasma levels of ANP and BNP were higher at rest in patients than in control subjects [ANP 335 (140–700) vs. 90 (25–500) pg mL⁻¹; BNP 42 (25–50) vs. 20 (10–20) pg mL⁻¹], and at peak exercise [ANP 400 (200–1000) vs. 130 (10–590); BNP 46 (40–51) vs. 20 (10–30)]. The rise in ANP at peak exercise was significant in patients compared with the resting level, but not in control subjects. For BNP, there was a significant rise in patients but no change in control subjects. The circulating plasma levels of both peptides showed a strong negative correlation with LVEF (ANP, P  < 0.005; BNP, P  < 0.0001) and, to a less extent, with RVEF. It is possible that BNP may give a better indication of cardiac function.     

Enhanced renal production of cyclic GMP and reduced free water clearance during sodium nitroprusside infusion in healthy man

Abstract. A 90–min intravenous infusion of the direct vasodilator sodium nitroprusside (SNP) was compared with a placebo infusion in 32 healthy control subjects in order to study the acute effects of SNP on renal haemodynamics, tubular function evaluated by the lithium clearance technique, the plasma levels of atrial natriuretic peptide (ANP), angiotensin II (Ang II), aldosterone (Aldo) and arginine vasopressin (AVP) and the tubular transport of cGMP (T_cGMP). SNP infusion induced a significant reduction in mean arterial blood pressure (from 89.5 to 81.5 mmHg), urinary output (from 7.7 to 4.5 ml min^-1), free water clearance (from 4.0 to 1.3 ml min-^I) and ANP (from 3.3 to 2.5 pmoll-¹) and a significant increase in heart rate (from 57 to 64 beats min^-l), Ang II (from 11 to 18 pmoll^-1), Aldo (from 189 to 308 pmol L^-1) and in the tubular secretion of cGMP (T_cgmP from 28.8 to 214.4 pmol min^-1), (all values are medians and changes from baseline to 90 min after infusion start). Glomerular filtration rate, renal plasma flow, urinary sodium excretion, lithium clearance and plasma level of AVP were not significantly changed. It is concluded that SNP infusion in healthy subjects decreases urinary output and free water clearance without any change in sodium excretion, indicating a dissociation between the salt and water retaining effects of SNP in the early phase of treatment, probably due to an enhanced distal tubular water reabsorption of water. It is suggested that this increase in reabsorption of water in the distal parts of the nephron during SNP infusion may be mediated by an increase of cGMP production in the kidney, as indicated by the increase in T_cGMP during the SNP infusion.     

SSC/ISTH classification of hemophilia A: can hemophilia center laboratories achieve the new criteria?

Summary.  To assess the practicality of the recent Scientific and Standardization committee (SSC) of the International Society on Thrombosis and Haemostasis (ISTH) recommendations in respect of the classification of hemophilia we distributed samples from three untreated subjects with hemophilia A to 91 UK hemophilia centers (HCs), comprising 20 comprehensive care centers (CCCs) and 71 HCs. Laboratories were requested to perform their routine factor (F)VIII:C assays and to classify the severity of hemophilia. Median values of < 1 U dL⁻¹ were obtained on two samples. However, for each of the two, approximately 30% of laboratories obtained results in the range 1–29 U dL⁻¹ and 1–33 U dL⁻¹ respectively. For one of these samples 17 laboratories diagnosed severe hemophilia despite obtaining FVIII:C levels in the range 1–5 U dL⁻¹. The median FVIII:C for the third sample was 5.8 U dL⁻¹ with a range of 1.5–36 U dL⁻¹. For this sample eight centers diagnosed severe hemophilia. Fifty-four laboratories obtained a result > 5 U dL⁻¹; 21 of these diagnosed mild hemophilia, 31 moderate hemophilia and two severe hemophilia. Results from CCCs were more accurate and more precise than those from HCs. Our results indicate a need for improved standardization of FVIII assays. In the UK there remains a lack of consensus in respect of the laboratory diagnostic criteria for the classification of hemophilia A.     

Novel Aα chain truncation (fibrinogen Perth) resulting in low expression and impaired fibrinogen polymerization

Summary.  A young woman with a history of menorrhagia and easy bruising presented with a functional fibrinogen concentration of 1.8 mg mL⁻¹, a gravimetric concentration of 3.3 mg mL⁻¹ and a prolonged thrombin clotting time of 32 s. Both reverse phase analysis and reducing SDS–PAGE revealed a normal profile of Aα, Bβ, and γ chains. However, non-reducing gels revealed a broadened 340-kDa band, while the 305-kDa band was normal, suggesting a C-terminal truncation of the Aα chain. DNA sequencing of all exons and intron boundaries revealed a single heterozygous cytosine deletion at nucleotide 4841 of the Aα gene predicting a frameshift and the incorporation of 23 new residues (LMKLPSSTLPQLEKHSQVSSHLC) before termination after residue 517. In agreement with a predicted mass decrease of 9953 Da, the measured mass of the Aα^Perth chain was 56 242 Da, while that of the normal Aα^A chain was 66 189 Da. Tryptic mapping of isolated Aα chains revealed a new [M + 2H] ion at 607 m z⁻¹, corresponding to the predicted penultimate peptide LPSSTLPQLEK. The variant chain was poorly incorporated into plasma fibrinogen at a ratio of Aα^Perth/Aα^A of 0.15 : 1, suggesting the Aα^Perth chain might be out-competed by normal chains during molecular assembly in the hepatocyte. Despite the low expression, polymerization curves showed a decreased V_max and final turbidity, suggesting the fibrinogen Perth clots are composed of thinner fibers. However, the fibrinolytic rate was very similar to that of the control.