Tissue factor is rapidly elevated in plasma collected from the pericardial cavity during cardiopulmonary bypass

There is growing evidence that the tissue factor/factor VIIa pathway of coagulation is enhanced during cardiopulmonary bypass. Hitherto, available evidence has suggested that upregulated monocyte bound tissue factor is made available, either in the blood collected from the site of surgery or on circulating cells. However, cellular upregulation is slow, while generation of factor VIIa in blood collected from the pericardial cavity is rapid. We have therefore investigated the possibility of an alternative source of tissue factor, plasma (as opposed to cellular) tissue factor in blood samples taken from the central vein catheter (systemic circulation) and collected from the pericardial cavity during cardiopulmonary bypass. Six patients undergoing first time cardiopulmonary bypass grafting were studied. Tissue factor antigen was found to be rapidly elevated (by 15 min) in the pericardial plasma, approximately 5-fold above systemic levels (p <0.004). Similar elevations were found in markers of coagulation activation, factor VIIa antigen (p = 0.066), prothrombin fragment F(1+2) (p <0.003) and thrombin-antithrombin complex (p <0.03). To explore whether plasma tissue factor was (or had been) functionally active, factor VIIa was measured also with the soluble tissue factor functional assay after removal of heparin. Functional factor VIIa activity fell significantly in the systemic circulation, probably due to the heparin-induced increase (approximately 15-fold) in tissue factor pathway inhibitor (TFPI), but was elevated in pericardial blood compared with that taken from the central line catheter (p <0.006). These results demonstrate that both components of the activation complex for the extrinsic pathway of coagulation are rapidly generated in pericardial blood during bypass.

Relationships between homocysteine, factor VIIa, and thrombin generation in acute coronary syndromes

BACKGROUND

It has been suggested by clinical, epidemiological, and experimental in vitro studies that homocysteine potentiates thrombin generation. This prothrombotic effect however has not previously been demonstrated in patients presenting with acute coronary syndromes (ACS).

METHODS AND RESULTS

Patients with ACS (n =117) presenting with confirmed acute myocardial infarction (MI) (n =57) or unstable angina pectoris (UAP) (n =60) were consecutively recruited together with patients (n =18) in whom the presenting chest pain was not of cardiac origin (NCP), included as controls. Plasma samples were collected on admission and before clinical intervention. Homocysteine was assayed by high performance liquid chromatography, and both Factor VIIa and prothrombin fragment F1+2 were analyzed by ELISA. There were significant elevations in F1+2 in MI (P<0.001) and UAP (P=0.003), and modest elevations in Factor VIIa in UAP (P<0.05) compared with NCP but no differences in homocysteine levels among those groups. On dividing patients with ACS into quartiles of homocysteine, there was a stepwise increase in F1+2 (P<0.0001) and of Factor VIIa (P<0.05). There were significant correlations in ACS between homocysteine and F1+2 (r=0.46, P<0.0001), homocysteine and Factor VIIa (r=0.24, P<0.01), and F1+2 and Factor VIIa (r=0.41, P<0.0001). There was no correlation between homocysteine and either F1+2 (r=-0.15, P=0.57) or Factor VIIa (r=0. 22, P=0.37) in the NCP patients.

CONCLUSIONS

Elevated plasma homocysteine is associated with and may cause elevated Factor VIIa and thrombin generation in patients presenting with ACS. These findings suggest an explanation for the prothrombotic effect of homocysteine in ACS.

Identification and characterization of a thrombomodulin gene mutation coding for an elongated protein with reduced expression in a kindred with myocardial infarction

Thrombomodulin is an endothelial cell receptor for thrombin. It functions as a natural anticoagulant by greatly accelerating activation of protein C by thrombin. Using a direct gene screening strategy we identified a frameshift insertion mutation, insT 1689, in the thrombomodulin gene of a patient with myocardial infarction. The mutation predicts an elongated gene product because of substitution of the 12 C-terminal amino acids by 61 abnormal residues. Pedigree analysis showed that the mutation was also likely to have been present in a sibling who had had fatal myocardial infarction. Carriers of the mutant allele express significantly lower amounts of thrombomodulin on the surface of their monocytes detected by flow cytometry and have lower levels of soluble thrombomodulin in plasma. Wild type and the mutant thrombomodulin were expressed in COS-7 cells. Cellular distribution of the expressed proteins was evaluated by immunofluorescence microscopy, which showed reduced cell surface expression and intense juxtanuclear localization of the abnormal protein. This suggests impaired translocation through the endoplasmic reticulum/Golgi apparatus. Cells expressing abnormal thrombomodulin had reduced ability ( approximately 2.5-fold) to accelerate the thrombin mediated activation of protein C. This is the first demonstration of reduced expression arising from a natural thrombomodulin gene mutation. The results provide support for the suggestion that gene mutation of thrombomodulin may be important in the pathogenesis of some cases of occlusive thrombotic disease. (Blood. 2000;95:569-576)

Determining exposure underreporting in pharmacoepidemiologic case-control studies: methods and example

Many pharmacoepidemiologic case-control studies have to rely on what their subjects relate about the drugs to which they have been exposed and the durations of exposure. There is often good reason to suppose that not all exposures are actually reported and to suspect reporting rates may differ between cases and controls. We introduce two procedures designed to determine the extent of underreporting of exposures. These procedures make use of data from the case-control study itself, as well as sales, demographic and market research data for a reference population to which study subjects belong. We apply these procedures to data from the International Primary Pulmonary Hypertension Study (IPPHS) linking anorexigens with PPH. We show that exposures to the anorectic agent dexfenfluramine beginning in or before 1989 were highly significantly underrepresented in the data for IPPHS controls, relative to exposures beginning after 1989 (P<0.01); there is no corresponding evidence for relative underrepresentation of early exposure for IPPHS cases. However, data on control exposures from 1990 to 1992 are consistent with the hypothesis that these exposures were not underreported to the IPPHS. Subject to certain key modeling assumptions and the availability of some supplemental data, it is possible to investigate the extent of underreporting of exposure in a pharmacoepidemiologic case-control study and in particular to determine if study results are likely to have been affected by recall bias.

Structural and functional implications of the intron/exon organization of the human endothelial cell protein C/activated protein C receptor (EPCR) gene: comparison with the structure of CD1/major histocompatibility complex alpha1 and alpha2 domains

The endothelial cell protein C/activated protein C receptor (EPCR) is located primarily on the surface of the large vessels of the vasculature. In vitro studies suggest that it is involved in the protein C anticoagulant pathway. We report the organization and nucleotide sequence of the human EPCR gene. It spans approximately 6 kbp of genomic DNA, with a transcription initiation point 79 bp upstream of the translation initiation (Met) codon in close proximity to a TATA box and other promoter element consensus sequences. The human EPCR gene has been localized to 20q11.2 and consists of four exons interrupted by three introns, all of which obey the GT-AG rule. Exon I encodes the 5' untranslated region and the signal peptide, and exon IV encodes the transmembrane domain, the cytoplasmic tail, and the 3' untranslated region. Exons II and III encode most of the extracellular region of the EPCR. These exons have been found to correspond to those encoding the alpha1 and alpha2 domains of the CD1/major histocompatibility complex (MHC) class I superfamily. Flanking and intervening introns are of the same phase (phase I) and the position of the intervening intron is identically located. Secondary structure prediction for the amino acid sequence of exons II and III corresponds well with the actual secondary structure elements determined for the alpha1 and alpha2 domains of HLA-A2 and murine CD1.1 from crystal structures. These findings suggest that the EPCR folds with a beta-sheet platform supporting two alpha-helical regions collectively forming a potential binding pocket for protein C/activated protein C.

Familial overexpression of beta antithrombin caused by an Asn135Thr substitution

We have investigated the basis of antithrombin deficiency in an asymptomatic individual (and family) with borderline levels (approximately 70% antigen and activity) of antithrombin. Direct sequencing of amplified DNA showed a mutation in codon 135, AAC to ACC, predicting a heterozygous Asn135Thr substitution. This substitution alters the predicted consensus sequence for glycosylation, Asn-X-Ser, adjacent to the heparin interaction site of antithrombin. The antithrombin isolated from plasma of the proband by heparin-Sepharose chromatography contained amounts of beta antithrombin (the very high affinity fraction) greatly increased (approximately 20% to 30% of total) above the trace levels found in normals. Expression of the residue 135 variant in both a cell-free system and COS-7 cells confirmed altered glycosylation arising as a consequence of the mutation. Wild-type and variant protein were translated and exported from COS-7 cells with apparently equal efficiency, in contrast to the reduced level of variant observed in plasma of the affected individual. This case represents a novel cause of antithrombin deficiency, removal of glycosylation concensus sequence, and highlights the potentially important role of beta antithrombin in regulating coagulation.

Early postpartum discharges. Impact on distress and outpatient problems

OBJECTIVE

To determine the impact of shortened postpartum hospital stays on common clinical phenomena in a sociodemographically diverse, unselected group of general maternity patients.

DESIGN

Observational cohort study in which the preapproved hospital stay duration of either 1 or 2 nights was set by third-party payers before each mother's admission.

SETTING

Yale-New Haven Hospital, New Haven, Conn, from June 19 through August 10, 1995.

PATIENTS

Two hundred forty-four volunteers from among 400 eligible deliveries.

MAIN OUTCOME MEASURES

Readmission within 1 month of hospital discharge, report of outpatient morbidity and use of outpatient health services within 1 week of discharge, status of breast-feeding during the first post-discharge week, and patient satisfaction.

RESULTS

At discharge from the hospital, the hospital stay was regarded as "too short" by 80 (47%) of 171 mothers and 19 (26%) of 73 mothers in the 1- and 2-night groups, respectively (P = .002). Although readmission rates were similar (5% vs 3%, P = .48), the 1-night group reported significantly more morbidity in the newborns (31% vs 16%, P = .03) and averaged more pediatric visits (96 vs 54 per 100 newborns, P = .002). Mothers in the 1-night group also reported more fatigue (49% vs 29%, P = .001) and more worries about their newborns' health (24% vs 11%, P = .02). They were less likely to start breast-feeding (64% vs 77%, P = .06), and, if they started, were somewhat more likely to stop prematurely (14% vs 8%, P = .43). A series of disturbing events was reported only in the 1-night group.

CONCLUSIONS

In a relatively unselected group, mothers who stayed 1 night after routine vaginal delivery reported more distress and more pediatric problems and had greater use of outpatient health services than mothers who stayed 2 nights.

Two-chain factor VIIa generated in the pericardium during surgery with cardiopulmonary bypass : relationship to increased thrombin generation and heparin concentration

Several recent studies have proposed that coagulation is triggered during cardiopulmonary bypass surgery by extrinsic pathway activation involving factor VIIa generation, but the methodology was indirect. Therefore, 12 patients were studied during routine cardiac and cardiopulmonary bypass surgery. Samples were taken before, during, and after bypass from the perfusate, from the aorta (retrograde cardiac drainage), pericardium, and collected suction fluid originating from the whole operative field. These samples were analyzed by enzyme-linked immunosorbent assay for 2-chain factor VIIa, by prothrombin F1+2 assay, by thrombin-antithrombin (TAT) assay, and for heparin concentration. Factor VIIa, F1+2, and TAT levels in samples from the pericardium were greatly elevated (mean, 0.92 to 1.01, 227 to 334, and 399 to 526 microg/L, respectively; preoperative mean, 0.33, 32.3, and 1.90 microg/L, respectively; P<0. 05 for all), whereas levels in suction fluid were less consistently high. Factor VIIa and both F1+2 and thrombin-antithrombin levels in samples from the aorta, pericardium, and suction fluid were significantly correlated (r=0.57, P<0.001, n=111; and r=0.51, P<0. 001, n=105, respectively), and all were inversely correlated with heparin levels (r>-0.35, P<0.001, n>92). There was no evidence of factor VIIa generation in the circuit during bypass surgery, and both F1+2 and thrombin-antithrombin levels rose only approximately 2-fold, probably because heparin levels were higher than they were in the pericardium (P<0.05). We concluded that appreciable activation of factor VII occurs on the pericardium and that this is associated with increased thrombin generation. Ineffective local heparinization may be partly responsible. These results suggest that pericardium-induced activation of factor VII should be the target of anticoagulant strategies during cardiopulmonary bypass surgery.

Impaired cotranslational processing as a mechanism for type I antithrombin deficiency

Most secretory proteins, including antithrombin (AT), are synthesized with a signal peptide, which is cleaved before the mature protein is exported from the cell. The signal peptide is important in the process whereby nascent protein is recognized as requiring subsequent modification within the endoplasmic reticulum (ER). We have identified a novel mutation, 2436T-->C L(-10)P, which affects the central hydrophobic domain of the AT signal peptide, in a proband presenting with venous thrombotic disease and type I AT deficiency. We investigated the basis of the phenotype by examining expression in mammalian cells of a range of variant AT cDNAs with mutations affecting the -10 residue. Glycosylated AT was secreted from COS-7 cells transfected with wild-type AT, -10L deletion, -10V or -10M variants, but not variants with P, T, R, or G at -10. Cell-free expression of wild-type and variant AT cDNAs was then performed in the presence of canine pancreatic microsomes, as a substitute for ER. Variant AT proteins with P, T, R, or G at residue -10 did not undergo posttranslational glycosylation, and their susceptibility to trypsin digestion suggested they had not been translocated into microsomes. Our results suggest that the ability of AT signal peptide to direct the protein to ER for cotranslational processing events appears to be critically dependent on maintaining the hydrophobic nature of the region including residue -10. The investigations have defined impaired cotranslational processing as a hitherto unrecognized cause of hereditary AT deficiency.

A mutation in the thrombomodulin gene, 127G to A coding for Ala25Thr, and the risk of myocardial infarction in men

Thrombomodulin is an endothelial cell surface receptor that transforms the procoagulant thrombin into an anticoagulant. A mutation in the thrombomodulin gene is a potential risk factor for venous and arterial thrombosis. We screened a region within the coding sequence of the thrombomodulin gene by single-strand conformation polymorphism analysis (SSCP) in a pilot study of 104 patients with myocardial infarction and 104 age, sex and race matched controls. We identified a 127G to A mutation in the gene, which predicts an Ala25Thr substitution, in 2 out of 104 patients (1 man and 1 woman) with myocardial infarction but in no controls. We assessed the risk of myocardial infarction associated with the mutation in a larger "Study of Myocardial Infarctions Leiden" (SMILE). Among 560 men with a first myocardial infarction before the age of 70, 12 were carriers of the Ala25Thr substitution. In a control group of 646 men, frequency-matched for age, seven were carriers of the Ala25Thr substitution. The allelic frequencies were 1.07% among patients and 0.54% among controls suggesting risk associated with the mutation [odds ratio (OR) 2.0, 95% confidence interval (CI) 0.8-5.1]. In patients aged below 50, the predicted risk was almost seven times increased (OR 6.5, CI 0.8-54.2). In the presence of additional risk factors, such as smoking and a metabolic risk factor, the predicted risk increased to 9-fold (OR 8.8. CI 1.8-42.2) and 4-fold (OR 4.4, CI 0.9-21.3), respectively. While not conclusive, these results strongly suggest that the Ala25Thr substitution is a risk factor for myocardial infarction, especially in young men, and when in the presence of additional risk factors.

Ambient light working times of visible light-cured restorative materials. Does the ISO standard reflect clinical reality?

OBJECTIVES

The aim of this study was to determine whether a custom built light box could reliably reproduce clinical conditions and whether the current ISO standard test for the working time of visible light cured (VLC) materials (ISO. Dental Resin-based Restorative Materials. ISO:4049, 1991) reflected clinical reality.

METHOD

The ISO test requires a VLC material to remain homogenous after exposure to an 8 kLux light source for 60 s. The relationship between the intensity of ambient lighting and the working times of visible light-cured (VLC) restorative materials was investigated by exposing 23 different VLC composite resin materials to a range of light intensities and measuring the working time in seconds: (a) under clinical operating conditions; (b) in a custom light box at 24 kLux; and (c) at 8 kLux in the light box. Working times were determined by placing 0.06 g samples between two glass plates and gently rotating until clefts or voids appeared.

RESULTS

Clinical lighting conditions (24 kLux) gave a mean working time of 54 s (s.d. 14 s). In the light box at 24 kLux the mean working time was 54 s (s.d. 11 s). At 8 kLux (under otherwise identical conditions) the mean working time was 162 s (s.d. 49 s).

SIGNIFICANCE

A 24 kLux illuminance in the laboratory gives an optimal correspondence to operative lighting conditions. This is three times the lighting level required for ISO purposes, and gives more realistic working times.

Aminorex, dexfenfluramine, and primary pulmonary hypertension

BACKGROUND

In the late 1960s, an epidemic of primary pulmonary hypertension (PPH) occurred in Europe shortly after the introduction of aminorex fumarate, a potent anorexigen. A recently published case-control study from Europe reported that use of other anorexigens (the most prevalent of which was dexfenfluramine) was also associated with an increased risk of PPH. This led to warnings of a repeat epidemic, especially after the introduction of dexfenfluramine on the North American market.

OBJECTIVE

To compare the epidemiologic associations of PPH with aminorex and dexfenfluramine, both with respect to strength of association (estimate of relative risk) and public health impact (etiologic fraction) and thus to assess the potential for a new epidemic of PPH.

METHODS

We constructed a "synthetic" case-control study for aminorex based on reported case series from Berne and Basel, Switzerland, and a random population sample from Hanover, Germany, and compared the results with those recently reported for dexfenfluramine. Control rates of exposure were used to estimate population exposure prevalences and, hence, etiologic fractions.

RESULTS

The estimated odds ratio (and 95% confidence interval) for the association between PPH and any exposure to aminorex was 97.8 (78.9-121.3), with a corresponding etiologic fraction of 77%. The corresponding figures for dexfenfluramine were 3.7 (1.9-7.2) and 17%, respectively.

CONCLUSION

The strong association between aminorex and PPH probably led to a 5-fold increase in PPH incidence, and thus a very noticeable epidemic. The association with dexfenfluramine would result in an increase in incidence of only 20%. Based on the available evidence, a repeat PPH epidemic seems unlikely.

Academic calculations versus clinical judgments: practicing physicians' use of quantitative measures of test accuracy

PURPOSE

To determine how often practicing physicians use the customarily recommended quantitative methods that include sensitivity, specificity, and likelihood ratio indexes; receiver operator characteristic (ROC) curves; and Bayesian diagnostic calculations.

PARTICIPANTS AND METHODS

A random sample of 300 practicing physicians (stratified by specialty to include family physicians, general internists, general surgeons, pediatricians, obstetrician/gynecologists, and internal medicine subspecialists) were briefly interviewed in a telephone survey. They were asked about the frequency with which they used the formal methods, the reasons for non-use, and if they employed alternative strategies when appraising tests' diagnostic accuracy.

RESULTS

Of the 300 surveyed physicians, 8 (3%) used the recommended formal Bayesian calculations, 3 used ROC curves, and 2 used likelihood ratios. The main reasons cited for non-use included impracticality of the Bayesian method (74%), and nonfamiliarity with ROC curves and likelihood ratios (97%). Of the 174 physicians who said they used sensitivity and specificity indexes, 165 (95%) did not do so in the recommended formal manner. Instead, the physicians directly estimated tests' diagnostic accuracy by determining how often the test results were correct in groups of patients later found to have, or to be free of, the selected disease.

CONCLUSIONS

The results indicate that most practicing physicians do not use the formal recommended quantitative methods to appraise tests' diagnostic accuracy, and instead report using an alternative direct approach. Although additional training might make physicians use the formal methods more often, the physicians' direct method merits further evaluation as a potentially pragmatic tool for the determination of tests' diagnostic accuracy in clinical practice.

Clarification of the risk for venous thrombosis associated with hereditary protein S deficiency by investigation of a large kindred with a characterized gene defect

BACKGROUND

Protein S is an important regulatory protein of the coagulation cascade. The risk for venous thrombosis associated with protein S deficiency has been uncertain because all previous risk estimates used phenotypic evaluation alone, which can be ambiguous.

OBJECTIVE

To quantitate the risk for thrombosis associated with a characterized protein S gene mutation that causes a Gly295-->Val substitution and protein S deficiency.

DESIGN

Retrospective study of a single extended family.

SETTING

University hospital referral center.

PARTICIPANTS

A 122-member protein S-deficient family, in which 44 members had a recently characterized gene defect.

MEASUREMENTS

Comprehensive history of thrombosis, history of exposure to acquired risk factors for thrombosis, levels of total and free protein S antigen, and genotype for the mutation causing the Gly295-->Val substitution.

RESULTS

Kaplan-Meier analysis of thrombosis-free survival showed that the probability of remaining free of thrombosis at 30 years of age is 0.5 (95% CI, 0.33 to 0.66) for carriers of the Gly295-->Val mutation compared with 0.97 (CI, 0.93 to 1.0) for normal family members (P < 0.001). In a multivariate Cox regression model that included smoking and obesity, the mutation was a strong independent risk factor for thrombosis (hazard ratio, 11.5 [CI, 4.33 to 30.6]; P < 0.001). For free (but not total) protein S antigen levels, the distributions of persons with and persons without the mutation did not overlap.

CONCLUSIONS

Protein S deficiency, as defined by the presence of a causative gene mutation or a reduced level of free protein S antigen, is a strong independent risk factor for venous thrombosis in a clinical affected family.

Activation of coagulation and fibrinolysis in childhood diarrhoea-associated haemolytic uraemic syndrome

Diarrhoea-associated haemolytic uraemic syndrome (D+ HUS) is usually caused by verotoxin producing Eschericia coli. We hypothesized that verotoxin binding to glomerular endothelial cells causes localised endothelial cell activation and thus activation of coagulation and reduction of fibrinolytic potential. We also proposed that treatment with fresh frozen plasma or dialysis would not affect these changes. Markers of activation of coagulation and fibrinolysis were measured in 30 children with acute D+ HUS serially, in healthy children and in children on dialysis. In acute D+ HUS, levels of thrombin-antithrombin III complex and prothrombin fragment 1+2 were significantly increased (p <0.001). The source of thrombin generation was unclear. Factor XIIa levels were increased in patients and controls with renal failure. Factor VIIa levels were not significantly raised in children with acute D+ HUS. D-dimers were increased, but fibrinolytic potential as measured by fibrin plate was reduced. Levels of plasminogen activator inhibitor antigen and activity and tissue plasminogen activator antigen were increased. Neither peritoneal dialysis nor administration of blood products, the most common treatments, altered parameters of coagulation or fibrinolysis.

Antithrombin: molecular basis of deficiency

Antithrombin is a plasma protein regulator of coagulation proteinase activity, particularly that of thrombin. Its deficiency is a risk factor for venous thromboembolism. Considerable progress has been made in understanding the organisation and function of the antithrombin gene and protein, and the molecular basis of deficiency, all of which are reviewed, but briefly, here.

Thrombomodulin gene mutations associated with myocardial infarction

BACKGROUND

Thrombomodulin is an important receptor for thrombin on the endothelial cell surface of most blood vessels, including those of the heart. Thrombin-bound thrombomodulin activates protein C, which inhibits thrombin generation by degrading factors Va and VIIIa. The aim of this study was to analyze the 5' region of the thrombomodulin gene to determine whether mutations contribute a risk for myocardial infarction.

METHODS AND RESULTS

We screened the promoter region of the thrombomodulin gene by single-stranded conformation polymorphism analysis in 104 patients with diagnosed myocardial infarction. Five mutations (three distinct) were identified (GG-9/-10AT, G-33A, and C-133A). The dinucleotide mutation GG-9/-10AT was identified in 3 individuals (2 heterozygous, 1 homozygous). Only one of the three different mutations was identified in 104 patient control subjects matched for age, sex, and race (G-33A in a single individual). All mutations identified were in close proximity to consensus sequences for transcription control elements within the thrombomodulin gene. In contrast, no difference was observed between patients and control subjects for the allelic frequency of a previously identified neutral polymorphism GCC/GTC coding for Ala/Val455, with 3 individuals homozygous for GTC (Val) in both groups.

CONCLUSIONS

The findings suggest that mutations in the promoter region of the thrombomodulin gene may constitute a risk for arterial thrombosis.

Antithrombin and its inherited deficiency states

Antithrombin is the primary inhibitor of thrombin that also inhibits many of the other activated serine proteinases involved in blood coagulation. A hypercoagulable state occurs when a deficiency of antithrombin exists in plasma; the deficiency may be either inherited or acquired. This failure to regulate adequately the activity of coagulation proteinases can, with additional provocation, result in clot formation and in the clinical presentation of thromboembolic disease. The structure and function of antithrombin, nature and heterogeneity of the molecular defects in the antithrombin gene associated with inherited antithrombin deficiency, prevalence and the natural history of inherited antithrombin deficiency are all reviewed here.

Genetic and phenotypic analysis of a large (122-member) protein S-deficient kindred provides an explanation for the familial coexistence of type I and type III plasma phenotypes

Protein S deficiency is a known risk factor for thrombosis. The coexistence of phenotypic type I (reduction in total and free antigen) and type III (reduction in free antigen only) protein S deficiencies in 14 of 18 families was recently reported. We investigated the cause of this phenotypic variation in the largest of these families (122 family members, including 44 affected individuals) using both molecular genetic and phenotypic analysis. We have identified a sole causative mutation (Gly295Val) in three family members representative of the variable phenotype. Complete cosegregation of the mutation with reduced free protein S antigen levels was found, regardless of the total antigen level. Analysis of phenotypic data showed high correlations between total protein S antigen and age in both normal and protein S-deficient family members, irrespective of gender. Free protein S antigen levels were not influenced by age, a finding explained by an association between beta-chain containing C4b-binding protein (C4bBP-beta+) antigen levels and age. We propose that the identified Gly295Val mutation causes quantitative, or type I, protein S deficiency, and that as age increases the total protein S antigen level normalizes with respect to the reference plasma pool, giving rise to a type III protein S-deficient phenotype.

Hospital ship doctrine in the United States Navy: the Halsey effect on scoop- and-sail tactics

Although hospital ships have a long history, naval strategists have paid little attention to their tactical employment in naval and amphibious warfare. Often employed as floating ambulances, operational doctrine for hospital ships did not permit their use as floating combat surgical hospitals until the final amphibious campaigns of World War II. Based on operational archives-ships' logs, war diaries, battle plans, and other official records-this essay traces the evolution of tactical doctrine on hospital ships from Guadalcanal to Inchon. Early in World War II, there were insufficient hospital ships to permit much flexibility in their employment. By the Philippine campaign in 1944, the increased availability of afloat medical assets prompted Third Fleet Commander Vice Admiral William F. Halsey to propose that the ships be used as acute surgical hospitals at the amphibious landing sites rather than as sea-going ambulances. Facing the prospect of a growing number of casualties for the major assaults being planned, Halsey needed to maximize medical and surgical efficacy and return-to-duty rates to conserve the fighting strength of his invasion forces. Admiral Chester A. Nimitz approved Halsey's proposal, and the battle plan at Iwo Jima combined the careful triage of casualties at the waterfront with early, forward employment of hospital ships. Despite more than 21,000 casualties at Iwo Jima, they were handled better than at any previous operation in the Pacific theater. The tactical doctrine for hospital ships suggested by Halsey has since been employed in every major amphibious operation, including Okinawa and Inchon, and has also been used in modern-era contingency and humanitarian missions.

Epidemiology of coagulation factors, inhibitors and activation markers: the Third Glasgow MONICA Survey. I. Illustrative reference ranges by age, sex and hormone use

Coagulation factor activity (fibrinogen, VII, VIII and IX), coagulation inhibitor activity (antithrombin, protein C, protein S), and coagulation activation markers (prothrombin fragment F1, 2; thrombin-antithrombin complexes) were measured in 747 men and 817 women aged 25-74 years, randomly sampled from the north Glasgow population in the Third MONICA Survey. Significant effects of age, sex, menopause and hormone use were observed and specific reference ranges are presented to illustrate these effects. Significant correlations were observed between several coagulation factors and inhibitors. Increased levels of factors VII, VIII and IX and decreased levels of protein C were associated with increased coagulation activation. In general, increases in coagulation factors with age were greater than increases in coagulation inhibitors, especially in men; this imbalance may favour increased coagulation activation and hence increased thrombotic risk with age.

Epidemiology of coagulation factors, inhibitors and activation markers: The Third Glasgow MONICA Survey. II. Relationships to cardiovascular risk factors and prevalent cardiovascular disease

Coagulation factor activity (fibrinogen, VII, VIII and IX), coagulation inhibitor activity (antithrombin, protein C, protein S), and coagulation activation markers (prothrombin fragment F1, 2; thrombin-antithrombin complexes) were measured in 746 men and 816 women aged 25-74 years, randomly sampled from the north Glasgow population in the Third MONICA Survey. After age-adjustment, significant associations with cardiovascular risk factors were observed. Serum cholesterol and triglyceride were associated with increases in factors VII and IX, as well as antithrombin, protein C and protein S; and with increased fibrinogen and factor VIII in women. Apart from factor VIII (related to blood pressure in men, but not in women), similar associations were observed for blood pressure and body mass index. Smoking status and/or smoking markers were related to fibrinogen, factor IX, antithrombin and protein S. Alcohol intake was related to protein S, and inversely to fibrinogen and antithrombin in men. Low social class was associated with fibrinogen, factor VIII, factor IX, and with antithrombin, protein S, and low protein C in men. Serum vitamin C was associated inversely with coagulation factors and coagulation inhibitors. The only associations of activation markers were with low serum vitamin C, and with alcohol consumption and low social class in men. Prevalent cardiovascular disease was associated only with fibrinogen. These associations of coagulation factors and inhibitors with cardiovascular risk factors are plausibly relevant to thrombotic risk in cardiovascular disease. In general, 'worse' values of risk factors are associated with increased plasma levels of both coagulation factors and inhibitors, without significant increase in coagulation activation markers. However, the association of lower serum vitamin C with increased coagulation activation markers is of potential therapeutic interest.

Decrease in factor VII coagulant activity during percutaneous transluminal coronary angioplasty by heparin-mediated lipolytic action

Levels of factor VII coagulant activity (FVII:C) and two-chain factor VIIa antigen (FVIIa:Ag) were measured in ten patients before and up to 6 h after receiving a bolus of heparin during percutaneous transluminal coronary angioplasty (PTCA). A significant and sustained post-heparin fall in the level of FVII:C was observed (approximately 30%) without any change in the level of FVIIa:Ag. The level of tissue factor antigen within the circulation remained unchanged. The observed decrease in FVII:C coincided with a significant decrease in triglyceride levels presumably due to lipoprotein and hepatic lipase released by the heparin. These findings appear to demonstrate a lipid (triglyceride) dependence of FVII:C. Thus, heparin may act indirectly as antithrombotic agent by limiting a lipid-dependent activation of the extrinsic pathway of coagulation.