Antibodies to Factor XII Are Distinct from Antibodies to Prothrombin in Patients with the Anti-phospholipid Syndrome

Patients with the anti-phospholipid syndrome (APS) have antiphospholipid antibodies (aPA) which are often targeted towards phospholipid binding proteins such as β2-glycoprotein I and prothrombin. Antibodies to factor XII (FXIIabs) have also been identified in some patients with APS. Factor XII (FXII) is a member of the kringle family of proteins which include plasminogen and prothrombin. Antibodies to prothrombin have been associated with myocardial infarction and have been shown to cross react with plasminogen.

Sixteen patients with APS and FXIIabs were investigated for the presence of antibodies to prothrombin, by enzyme linked immunosorbent assay in a calcium (Ca++) independent assay. All sixteen showed different antibody binding patterns than those observed for antibodies to FXII.

Eight patients were further investigated using surface plasmon resonance (SPR) for antibody binding to covalently bound FXII and to covalently bound prothrombin in both Ca++ dependent and independent systems. Of three patients demonstrating antibody binding to FXII by SPR, none demonstrated antibody binding to prothrombin in a Ca++ independent system with one demonstrating antibody binding to prothrombin that was Ca++ dependent. Of five patients who did not bind FXII by SPR, one demonstrated antibody binding to prothrombin in a Ca++ independent system while two demonstrated antibody binding to prothrombin in a Ca++ dependent system. Antibodies to FXII in patients with APS appear to be distinct from antibodies to prothrombin.

Antibodies to Factor XII Associated with Lupus Anticoagulant

Falsely low levels of factor XII (FXII) have been documented in patients who are lupus anticoagulant positive (LA+). In addition, we have previously noted a surprisingly high incidence (20.9%) of apparently true FXII deficiency in patients who were LA+. We have hypothesised that this may be partly due to the presence of antibodies to FXII.

The aim of the present study was to investigate whether LA+ patient plasmas contain antibodies directed either against FXII or FXII in association with phospholipids. Plasma samples from 60 blood donors, all LA negative, and 51 LA+ patients were tested using ELISA assays employing purified FXII, phosphatidylserine (PS) and phosphatidylethanolamine (PE). We have identified seven patients whose plasma contained either IgG or IgM that reacted with purified FXII in the absence of PS or PE. When PS was included in the assay system four additional patient plasmas were shown to contain either IgG or IgM that reacted with FXII. The plasma of one patient contained IgG that reacted with FXII both in the presence and absence of PS. There was no reactivity to FXII with either IgG or IgM when PE was included in the assay system. Affinity purified IgG from three patients whose plasma reacted with FXII in the ELISA assay in the absence of PS, gave a positive reaction in an immunoblot assay. These results suggest that FXII antibodies are present in a significant proportion of LA+ patients and may lead to an erroneous diagnosis of FXII deficiency.

Factor XII Determinations in the Presence and Absence of Phospholipid Antibodies

Factor XII (FXII) levels were determined in plasma samples from 29 normal donors, 10 patients with inherited FXII deficiency (all lupus anticoagulant [LA] negative) and 67 LA positive patients, using clotting (FXIIct), chromogenic substrate (FXIIcs) and immunochemical (FXIIag) assays. Excellent correlations were obtained in the three FXII assays with the LA negative samples and between the FXIIcs and FXIIag assays in the LA positive samples. Correlations between both the FXIIcs and FXIIag with FXIIct in the LA positive patients were poor. Of 67 LA positive samples studied, 25 (37.3%) showed lower values in the FXIIct assay; 13 (19.4%) of these patients were pseudo FXII deficient with values of FXII below the lower limit of normal.

These results indicate that a diagnosis of FXII deficiency can be made inappropriately in the presence of phospholipid antibodies and that such a diagnosis should not be made by FXIIct assay alone.

A crystallographic study of ammonium and rubidium imidodisulphates

Ammonium und Rubidium-Imidodisulphat, NH(SO3NH4)2 und NH(SO3Rb)2, sind monoklin und strukturell verwandt, aber nicht isotyp mit Kalium-Imidodisulphat. Die Verfeinerung mittels Ausgleichsmethode auf Grund z.T. dreidimensionaler Interferenzdaten führte für 292 Reflexe zu R = 0,29. Trotz der in Überstrukturreflexen sich äußernden Abweichungen von der angenommenen Symmetrie, konnten Abstände von 1,74 ± 0,04 Å für S-Ν und von im Mittel 1,48 ± 0,03 Å für S-O bestimmt werden, die denen der Kaliumverbindung entsprechen. Für die Rubidiumverbindung war die Verfeinerung unbefriedigend; die wirkliche Struktur muß von der angenommenen stärker abweichen als bei den anderen Verbindungen. Die Ultrarotspektren bei Raumtemperatur sind für die Imidodisulphate von Ammonium, Kalium und Rubidium sehr ähnlich. Die magnetischen Kernresonanzlinien der Ammonium- und der Rubidiumverbindung verbreitern sich nicht nennenswert beim Übergang von 280° Κ zu 80 °K.

A strength-endurance index for power grip

INTRODUCTION

The purpose of this study was to quantify muscle strength and endurance in power grip.

METHOD

Workers (74 M and 74 F, 18-72 years) squeezed a dynamometer for a 60 s, 18-cycle test. Initial strength (IS) and final strength (FS) were calculated as the mean peak force for cycles 1-3 and 16-18, respectively. Endurance was defined by the strength decrement index (SDI) where SDI = (IS - FS)/IS x 100. A grip strength-endurance analyzer was constructed from IS and SDI data which were depicted on two parallel, linearly scaled axes. Discrete IS and SDI scores were connected on each axis with a vector. The vector (Vmag) was measured directly from the analyzer and its direction identified from its slope. Integer scales transformed discrete IS and SDI scores into individual strength-endurance performance scores (SEPS).

RESULTS

Better than 95% of the sample (n > or = 141) scored within acceptable test ranges defined as the combined sample mean +/- 2SD, for SDI, Vmag and SEPS. Vmag was the best predictor for SEPS. Linear regression for SEPS was SEPS (combined) = 0.09 (Vmag) - 0.29: (SEE = 0.829). The analyzer revealed individual scores outside acceptable ranges for injured and uninjured efforts.

CONCLUSION

The development of a power grip strength-endurance analyzer provided a simple method to graph individual power grip performances. Converting strength and endurance scores to integers and summing them (SEPS) provided a simple means to represent individual estimates of power grip strength-endurance performance.

Development of explicit criteria to measure adherence to hypertension guidelines

Measures of adherence to hypertension guidelines have historically been based on prescription data or physician survey data regarding treatment practices. These methods have limitations that decrease their accuracy. As part of a randomized controlled study testing the effects of pharmacist/physician collaboration on adherence to hypertension guidelines, the investigators and an expert panel developed a JNC 7 measurement tool. The final guideline adherence measurement tool includes 22 explicit criteria in four domains of care. An exploratory factor analysis, conducted to assess the structure of the tool, suggests three underlying treatment dimensions in hypertension care. The adherence measurement tool will allow researchers to link specific elements of care to improved blood pressure control. In addition, use of the tool will provide clinicians with a taxonomy for evaluating practice and describing the effect of improved patient care on patient outcomes.

Cardiovascular disease risk factors in habitual exercisers, lean sedentary men and abdominally obese sedentary men

OBJECTIVE

To investigate whether the favourable cardiovascular disease (CVD) risk factor profile of habitual exercisers is attributable to exercise or leanness.

DESIGN

Cross-sectional study of 113 nonsmoking men aged 30-45 y. CVD risk factors were compared in exercisers (n=39) and sedentary men (n=74), and in subgroups of lean exercisers (n=37), lean sedentary men (n=46) and obese sedentary men (n=28). Waist girth was used to identify lean (<100 cm) and abdominally obese (> or =100 cm) subgroups.

MEASUREMENTS

Blood pressure, physical activity (7-day recall), physical fitness (maximum oxygen consumption) and fasted lipoproteins, apolipoprotein (apo) B, triglycerides, glucose and fibrinogen.

RESULTS

Exercisers were fitter and leaner than sedentary men and had a better CVD risk factor profile. Total cholesterol, LDL-cholesterol and apo B concentrations were lower in lean exercisers than in lean sedentary men, suggesting that exercise influences these risk factors. Indeed, time spent in vigorous activity was the only significant predictor of total cholesterol and LDL-cholesterol in multiple linear regression models. Exercise status had little influence on triglycerides and HDL-cholesterol (HDL-C), and unfavourable levels were only evident among obese sedentary men. Waist girth was the sole predictor of triglycerides and HDL-C, explaining 44 and 31% of the variance, respectively.

CONCLUSIONS

These findings suggest that the CVD risk factor profile of habitual exercisers is attributable to leanness and exercise. Leanness is associated with favourable levels of HDL-C and triglycerides, while exercise is associated with lower levels of total cholesterol, LDL-cholesterol and apo B.

Urokinase induced fibrinolysis in thromboelastography: a model for studying fibrinolysis and coagulation in whole blood

BACKGROUND

The contact system (CS) proteins, factor XII and prekallikrein are thought to have roles in blood coagulation and fibrinolysis. Recent research has suggested that the CS proteins might be more important in fibrinolysis and cell function than in coagulation. Most studies on fibrinolysis have used plasma or euglobulin assays, ignoring the influence of cellular elements of blood on the fibrinolytic process.

OBJECTIVE AND METHODS

In order to study both coagulation and fibrinolysis in whole blood (WB), we have developed a thromboelastography (TEG) assay to investigate both coagulation and fibrinolysis in the same blood sample. In this assay, named urokinase (UK) induced fibrinolysis in thromboelastography (UKIFTEG), TEG is performed on recalcified citrated WB in the presence of UK. Large variations in Ly60 (percentage lysis 60 min after clot formation) were obtained between different donors with the same UK concentration. The UKIFTEG assay was therefore performed using UK concentrations that gave Ly60 values in the approximate range of 20-40%.

RESULTS

The effect of CS activation was investigated in the presence or absence of celite (10 mg mL(-1) blood). Celite shortened the clotting time (CT), and increased Ly60 values. Factor XIIa (FXIIa) and plasma kallikrein (KK) produced concentration dependent reductions in CT (significant at concentrations of 1303 and 2600 ng mL(-1) blood, respectively) and increased Ly60 values (significant at concentrations of 652 and 1300 ng mL(-1) blood, respectively).

CONCLUSIONS

Our results show that CS activation and both FXIIa and KK produce reductions in clotting time and enhanced fibrinolysis in UKIFTEG.

The antigenic binding site(s) of antibodies to factor XII associated with the antiphospholipid syndrome

Phospholipid binding proteins, including factor XII (FXII), are known to be targeted by antiphospholipid antibodies (aPA). Factor XII antibodies (FXIIab) have been described in some patients with the antiphospholipid syndrome (APS) and have been shown to lead to reduced levels of FXII. The antigenic binding site(s) and the pathophysiological effects of FXIIab are unknown. In an attempt to elucidate the binding site of these antibodies, immobilized plasma kallikrein was used to cleave FXII into its 52-kDa heavy-chain (HCFXII) and 28-kDa light-chain (LCFXII) components. Plasma samples from 12 female patients with definite APS and FXIIab were investigated for the presence of antibodies to FXII, HCFXII and LCFXII. All but one patient's plasma reacted to FXII, HCFXII and LCFXII in a similar manner. One patient gave markedly reduced positivity to HCFXII and LCFXII, suggesting that the FXIIab in this patient had a higher affinity for the intact FXII molecule. To further investigate the antigenic binding site(s) of FXII, 150 biotinylated peptides of the known FXII sequence were synthesized using a Multipin(TM) peptide synthesis procedure. The IgG and IgM fractions of the 12 patients' plasma were purified by affinity chromatography. The synthesized peptides were captured on streptavidin plates and individual patients' purified FXIIab assayed against the peptides in a modified enzyme-linked immunosorbent assay (ELISA). Two regions were identified as possible antigenic binding site(s) for FXIIab: one in the growth factor domain and the other in the catalytic domain.

Putting dental mercury pollution into perspective

This paper deals with the issue of amalgam waste from dental offices. The aim is to put into perspective the very small contribution of dental mercury to the overall volume of mercury discharged into the environment each year. While the amount discharged from dental offices is very small compared to other sources, the amount discharged into the environment from amalgam fillings in people's mouths is estimated as less than 2% of the amount from dental offices. At least 50% of mercury in the environment comes from natural sources. The major source of man-made mercury pollution is the industrial burning of fossil fuels. It is important to distinguish between inorganic mercury and organic mercury in terms of the impact on the health of the population.

Mechanical properties of commercial high strength ceramic core materials

OBJECTIVE

The objective of the present study is to evaluate and compare the flexural strength, dynamic elastic moduli and true hardness (H(o)) values of commercial Vita In-Ceram alumina core and Vita In-Ceram matrix glass with the standard aluminous porcelain (Hi-Ceram and Vitadur), Vitadur N and Dicor glass and glass-ceramic.

METHODS

The flexural strength was evaluated (n=5) using 3-point loading and a servo hydraulic Instron testing machine at a cross head speed of 0.5 mm/min. The density of the specimens (n=3) was measured by means of the water displacement technique. Dynamic Young's shear and bulk moduli and Poisson's ratio (n=3) were measured using a non-destructive ultrasonic technique using 10 MHz lithium niobate crystals. The true hardness (n=3) was measured using a Knoop indenter and the fracture toughness (n=3) was determined using a Vickers indenter and a Tukon hardness tester. Statistical analysis of the data was conducted using ANOVA and a Student-Newman-Keuls (SNK) rank order multiple comparative test.

RESULTS

The SNK rank order test analysis of the mean flexural strength was able to separate five commercial core materials into three significant groups at p=0.05. Vita In-Ceram alumina and IPS Empress 2 exhibited significantly higher flexural strength than aluminous porcelains and IPS Empress at p=0.05. The dynamic elastic moduli and true hardness of Vita In-Ceram alumina core were significantly higher than the rest of the commercial ceramic core materials at p=0.05.

SIGNIFICANCE

The ultrasonic test method is a valuable mechanical characterization tool and was able to statistically discriminate between the chemical and structural differences within dental ceramic materials. Significant correlation was obtained between the dynamic Young's modulus and true hardness, p=0.05.

Depletion and restoration of endogenous monoamines affects β-CIT binding to serotonin but not dopamine transporters in non-human primates

The radioligand [123I]beta-CIT binds to dopamine transporters in striatum and to serotonin transporters in brainstem. Endogenous dopamine or serotonin may compete with radioligand binding at monoamine transporters. We used alpha-methyl-p-tyrosine (AMPT) to block dopamine production and measured [123I]beta-CIT binding before and after endogenous dopamine was restored by IV administration of the dopamine precursor L-dihydroxyphenylalanine (L-DOPA) in rhesus monkeys. P-chlorophenylalanine (pCPA) was used to inhibit serotonin production, and [123I]beta-CIT binding was assessed before and after IV administration of the serotonin precursor 5-hydroxy-L-tryptophan (L-5-HTP) restored endogenous serotonin. Pretreatment with benserazide blocked peripheral decarboxylization in both paradigms. Serotonin restoration measurably displaced [123I]beta-CIT binding to brainstem serotonin transporters but not to striatal dopamine transporters. Restoration of dopamine apparently did not affect [123I] beta-CIT binding to striatal dopamine transporters. However, dopamine restoration reduced radioligand binding to brainstem serotonin transporters, most likely due to dopamine release from serotonin neurons following L-DOPA administration. The higher striatal density of dopamine transporters relative to dopamine concentrations may explain why [123I] beta-CIT displacement by endogenous dopamine was not observed. This study indicates that [123I]beta-CIT binding in brainstem (raphe area) is affected by endogenous serotonin release in vivo and that L-DOPA treatment may cause serotonin neurons in the brainstem to corelease dopamine.

Serotonin transporter availability correlates with alcohol intake in non-human primates

A low level of alcohol intoxication upon initial exposure and impulsive aggressiveness predispose humans to alcoholism. In non-human primates, central serotonin transporter availability and turnover rate were associated with aggressive behavior and a low response to initial alcohol exposure. We assessed the respective effects of these factors on alcohol intake in a free choice paradigm. Serotonin transporter availability in the raphe area, the origin of central serotonergic projections, was measured with single-photon emission computed tomography and the radioligand [(123)I]beta-CIT in 11 rhesus monkeys with low and high central serotonin turnover. The amount of alcohol intake in the 3-month observation period was positively correlated with serotonin transporter availability (R=0.76, P=0.006), but not with aggressiveness (R=0.19, P=0.6) or alcohol response upon first exposure (R=-0.48, P=0.2). In a linear multiple regression analysis with serotonin transporter availability, alcohol response, and aggressiveness as independent variables, 82% of the variance of alcohol intake was explained and serotonin transporter availability emerged as the only statistically significant factor (beta=7.81, P=0.006). These observations indicate that there may be a direct relationship between serotonin transporter availability and alcohol intake after controlling for aggression and alcohol response on first exposure.

Changes in high molecular weight kininogen levels during and after cardiopulmonary bypass surgery measured using a chromogenic peptide substrate assay

High molecular weight kininogen (HK) is a co-factor in the blood-contact activation system. A chromogenic peptide substrate assay for HK (HKcs) has been developed in which test plasmas are mixed with diluted HK-deficient plasma and incubated with a soluble contact system activator that activates prekallikrein and factor XII. Calcium chloride, a synthetic thrombin inhibitor and a chromogenic peptide substrate for activated factor X (FXa) are then added. The FXa generated cleaves the FXa substrate releasing p-nitroanaline, which is measured photometrically. Test plasma HK values were calculated from a standard curve generated using a pooled normal plasma. Acceptable intra-assay and inter-assay precision values were obtained and levels of HK up to 200% were measurable. The assay measured HK in plasmas deficient in factor XII, prekallikrein and factor XI, was not affected by antiphospholipid antibodies and gave an acceptable correlation (r = 0.95) when normal plasmas and mixtures of HK-deficient and normal pooled plasma, calculated to give HK levels of 25 and 50%, were compared using HKcs and a HK one-stage clotting assay. The HKcs was used to measure HK levels in seven patients undergoing cardiopulmonary bypass (CPB). HK levels fell significantly during CPB (P = 0.0014) and were significantly higher (P = 0.016) 6 days after CPB, suggesting that HK may be a positive acute-phase reacting protein.

Relationship between cortisol and serotonin metabolites and transporters in alcoholism [correction of alcolholism]

BACKGROUND

Stress hormone activation may induce clinical depression via an interference with central serotonergic neurotransmission. In alcoholics, a reduction in serotonin transporters was associated with clinical depression, and an activation of cortisol secretion is frequently found during detoxification. We assessed the interaction between stress hormone activation, serotonin transporters, monoamine metabolites in the cerebrospinal fluid (CSF), and mood states in male and female alcoholics and healthy control subjects.

METHODS

The availability of serotonin transporters was measured with [I-123]beta-CIT and SPECT in the raphe area of the brainstem in 31 alcoholics after four weeks of abstinence and in 25 age-matched healthy volunteers. Concentrations of plasma cortisol were measured on the day of the SPECT scan. Within one week after the SPECT scan, we assessed monoamine metabolites and corticotropin-releasing factor (CRF) in the CSF.

RESULTS

Clinical depression was associated with a reduction in serotonin transporter availability among male alcoholics. Among male alcoholics and healthy volunteers, CSF 5-HIAA and plasma cortisol concentrations were inversely correlated with the availability of raphe serotonin transporters and positively correlated with the severity of clinical depression. No significant correlations were observed between raphe serotonin transporters and HVA, MHPG and CRF concentrations in the CSF.

CONCLUSION

Our findings support the hypothesis of an interaction between reduced serotonin transporters, stress hormone activation and clinical depression. They confirm the hypothesis that serotonergic neurotransmission dysfunction in alcoholism is limited to male alcoholics. The observed interactions between high cortisol concentrations and reduced serotonin transporter availability warrant further studies in major depression and other neuropsychiatric diseases with implied cortisol activation and serotonergic dysfunction.

Therapeutic considerations in the treatment of obesity hypertension

Obesity, now recognized as an independent risk factor for cardiovascular disease, is closely associated with hypertension. Complex mechanisms link increasing body weight with increasing blood pressure. Treatment of the obese patient with hypertension requires consideration of physiologic changes related to obesity hypertension. Lifestyle modification, including weight reduction and increased physical activity, can directly influence blood pressure levels and improve blood pressure control in obese, hypertensive patients. Clinical trials are needed to determine the most effective antihypertensive drugs for the obese, hypertensive patient. Antiobesity drugs offer viable adjunctive pharmacotherapy for obesity hypertension, but additional long-term studies are needed to support their safety and efficacy.

Associations between weight gain and incident hypertension in a bi-ethnic cohort: the Atherosclerosis Risk in Communities Study

OBJECTIVE

To examine associations between weight gain and changes in blood pressure and the incidence of hypertension in four ethnicity-gender groups.

DESIGN

Longitudinal closed cohort studied over an average of 6 y.

SUBJECTS

Total of 9309 white and African-American men and women 45-64 y of age who participated in the Atherosclerosis Risk in Communities (ARIC) Study.

METHODS

Weight and blood pressure were measured at baseline and after an average of 3 and 6 y of follow-up. Proportional hazard models with weight gain as a time-dependent variable were used to examine the association between weight gain and changes in blood pressure and hypertension. Multivariate models were used with baseline SBP, DBP, age, BMI, height, WHR, smoking, physical activity, education, caloric intake, fat intake and study center as covariates.

RESULTS

Weight gain was associated with increases in SBP and DBP in all groups. Hazard ratios for hypertension associated with 1 kg annual weight gain were 1.36 (95% CI, 1.29, 1.45) in white women, 1.12 (95% CI, 1.03, 1.21) in African-American women, 1.35 (95% CI, 1.27, 1.43) in white men and 1.43 (95% CI, 1.27,1.61) in African-American men.

CONCLUSION

Weight gain was associated with increased blood pressure and increased incidence of hypertension. The association was weaker among African-American women compared to other ethnicity-gender groups.

Ankle-brachial index and 7-year ischemic stroke incidence: the ARIC study

BACKGROUND AND PURPOSE

Low ankle-brachial index (ABI), which is the ratio of tibial artery systolic blood pressure to brachial systolic artery pressure, is known to be a measure of lower limb peripheral artery disease as well as a marker for other cardiovascular disease events. The ability of ABI to predict incident ischemic stroke, however, is not established in population-based studies.

METHODS

ABI was measured in a cohort of 14 839 black and white men and women aged 45 to 64 years. Stroke incidence was calculated during approximately 7 years of follow-up.

RESULTS

A total of 206 incident strokes occurred. Adjusted stroke incidence rates were markedly higher for those in the lowest versus the highest categories of ABI for men, women, blacks, and whites. The proportional hazards regression model, adjusted for age, race, gender, and field center, showed an inverse linear trend between ABI and ischemic stroke incidence (P<0.0001). The lowest group (ABI <0.80) had a hazard ratio of 5.68 (95% CI 2.77 to 11.66). After adjustment for major risk factors in a multivariate model, the hazard ratio in the lowest group was elevated (1.93) but no longer statistically significant (95% CI 0.78 to 4.78). There was, however, still an indication of an overall inverse linear trend between ABI and incident stroke (P=0.03).

CONCLUSIONS

Low ABI was strongly associated with increased incidence of ischemic stroke, but the relationship was substantially reduced after adjustment for major cardiovascular risk factors.

Antihypertensive effect of alpha- and beta-adrenergic blockade in obese and lean hypertensive subjects

The purpose of this study was to determine the contribution of the adrenergic system in mediating hypertension in obese and lean patients. Thirteen obese, hypertensive patients with a body mass index (BMI) > or =28 kg/m2 (obese) and nine lean patients with a BMI < or =25 kg/m2 (lean) were recruited. After a 1-week washout period, participants underwent daytime ambulatory blood pressure monitoring (ABPM). Participants were then treated with the alpha-adrenergic antagonist doxazosin, titrating to 4 mg QHS in 1 week. In the next week, the beta-adrenergic antagonist atenolol was added at an initial dose of 25 mg/day and titrated to 50 mg/day within 1 week. One month after the addition of atenolol, all patients underwent a second ABPM session. There were no differences between the obese and lean subjects in baseline systolic (SBP), diastolic (DBP), or mean arterial pressures (MAP) measured by office recording or ABPM. However, obese subjects had higher heart rates than lean subjects (87.5+/-2.4 v 76.8+/-4.9 beats/min). After 1 month of treatment with the adrenergic blockers, obese patients had a significantly lower SBP (130.0+/-2.5 v 138.9+/-2.1 mm Hg, P = .02) and MAP (99.6+/-2.3 v 107.0+/-1.5 mm Hg, P = .02) than lean patients. Obese patients also tended to have a lower DBP than lean patients (84.3+/-2.5 v 90.9+/-1.6 mm Hg, P = .057), but there was no significant difference in heart rate after 1 month of adrenergic blockade. These results indicate that blood pressure is more sensitive to adrenergic blockade in obese than in lean hypertensive patients and suggest that increased sympathetic activity may be an important factor in the maintenance of hypertension in obesity.

Antibodies to factor XII and recurrent fetal loss in patients with the anti-phospholipid syndrome

Forty female patients with either primary anti-phospholipid syndrome (n = 26) or systemic lupus erythematosus (anti-phospholipid syndrome positive) (n = 14) were investigated for levels of factor XII, the presence of lupus anticoagulant and antibodies to cardiolipin, beta 2-glycoprotein I and factor XII. Twenty-one patients had a history of recurrent fetal loss (> 2, mean = 2.6). Lupus anticoagulant positivity showed a weak association with recurrent fetal loss (odds ratio = 1.1). While there was no association between the presence of antibodies to cardiolipin or beta 2-glycoprotein I with recurrent fetal loss, antibodies to factor XII showed a strong and statistically significant association (odds ratio = 5.4, P = 0.025).

The importance of locally derived reference ranges and standardized calculation of dilute Russell's viper venom time results in screening for lupus anticoagulant

Three commercial dilute Russell's viper venom time (DRVVT) kits were evaluated at four UK centres experienced at performing lupus anticoagulant (LA) tests. Each centre established a normal reference range for the DRVVT ratio calculated against local pooled normal plasma from 20 healthy normal subjects. Plasma from LA-positive patients and LA-negative thrombophilia patients was also tested. DRVVT ratios and the degree of correction were assessed in a variety of ways to reflect not only the UK national Guidelines, but also the manufacturers' recommendations. The reference range data showed a normal distribution in each case, but considerable variation in the mean and SD between the centres and reagents, with the mean +2SD value ranging from 1.06 to 1.19. The use of an arbitrary DRVVT ratio of < 1.1 as the cut-off value for normality, which is applied in many laboratories, is therefore inappropriate. Although no single kit had a clear overall advantage in terms of sensitivity and specificity, the way in which the screen and confirmation data were analysed had a major impact on the interpretation of the results. A data analysis method employing a mean plus two standard deviations (SDs) cut-off for normality, and judgement regarding confirmation of LA based on a percentage correction of DRVVT ratio, was the simplest and most consistent, with overall sensitivity and specificity values of 81% and 94%, respectively, for uncomplicated LA-positive and LA-negative thrombophilia samples. We conclude that the 1991 BSCH Guidelines are in need of revision, each laboratory should establish its own normal reference range for the DRVVT ratio and a common method should be used for calculating the degree of correction with confirmation reagents, so that LA results can be correctly interpreted between laboratories. Standardizing DRVVT interpretation in this way should improve the consistency of LA detection.

Adenosine preconditions against endothelin-induced constriction of coronary arterioles

Myocardial hypoperfusion is accompanied by concomitant increases in adenosine and endothelin-1 (ET-1) production, but the vasodilatory effect of adenosine prevails over that of ET-1. Therefore, we hypothesized that adenosine-induced or ischemic preconditioning reduces the vasoconstrictive effect of ET-1. Coronary arteriolar diameter in vivo was measured using fluorescence microangiography in anesthetized open-thorax dogs. ET-1 (5 ng. kg(-1). min(-1) administered intracoronary, n = 10) induced progressive constriction over 45 min [25 +/- 6% (SE)]. The constriction was blocked by preconditioning with adenosine (25 microgram. kg(-1). min(-1) administered intracoronary) for 20 min and 10 min of washout (n = 10) or attenuated by ischemic preconditioning (four 5-min periods of ischemia, 9 +/- 5% at 45 min). To investigate the receptor involved in this process, coronary arterioles (50-150 micrometer) were isolated and pressurized at 60 mmHg in vitro. The ET-1 dose-response curve (1 pM-5 nM) was rightward shifted after preconditioning with adenosine (1 microM) for 20 min and 10 min of washout (n = 11). Blockade of A(2) receptors [8-(3-chlorostyryl)caffeine, 1 microM, n = 9] but not A(1) receptors (8-cyclopentyl-1,3-dipropylxanthine, 100 nM, n = 7) prevented this shift. These results suggest that adenosine confers a vascular preconditioning effect, mediated via the A(2) receptor, against endothelin-induced constriction. This effect may offer a new protective function of adenosine in preventing excessive coronary constriction.

Neuropharmacological studies with SPECT in neuropsychiatric disorders

The last decade saw a rapid development of single photon emission computed tomography (SPECT) from a tool to assess cerebral blood flow to the study of specific neurotransmitter systems. Because of the relatively long half-life of SPECT radioisotopes, it is practical to measure the availability of neuroreceptors and transporters in conditions approaching equilibrium. The cost-efficiency of SPECT allowed studies in relatively large samples of patients with various neuropsychiatric disorders. We have applied this approach in studies of dopaminergic, serotonergic, and muscarinergic neurotransmission in patients with dementia, extrapyramidal disorders, schizophrenia, and alcoholism. No simple associations were observed between a single defect in one neurotransmitter system and a certain neuropsychiatric disease. Instead, complex dysfunction of several neurotransmitter systems in multiple, partially connected brain circuits have been implicated. Treatment effects also have been characterized. Microdialysis and neurotransmitter depletion studies showed that most radioligands and endogenous neurotransmitters compete for binding at receptors and transporters. Future research directions include the assessment of endogenous neurotransmitter concentrations measured by depletion studies and of genetic effects on neuroreceptor and transporter expression.

Reduced factor XII levels in patients with the antiphospholipid syndrome are associated with antibodies to factor XII

Antibodies to factor XII (FXII) have previously been identified in some patients who were lupus anti-coagulant-positive. The relationship between these antibodies and FXII levels appeared to be variable. The aim of the present study was to confirm the presence of antibodies to FXII in patients with well characterized antiphospholipid syndrome (APS) and to establish their potential effect on levels of FXII. Forty-two patients with APS were studied; 21 patients were found to have either immunoglobulin (Ig)G or IgM antibodies to FXII by enzyme-linked immunosorbent assay (ELISA) using a highly purified preparation of FXII (> 99% pure). Levels of FXII were statistically significantly lower (P = 0.02) in patients with antibodies to FXII when compared with patients without antibodies to FXII (median = 91 micro/dl, s.d. = 39.1, median = 122 micro/dl, s.d. = 41.1 respectively). Four of the 21 patients with antibodies to FXII were found to have FXII levels below the laboratory normal range. Antibodies to FXII are present in significant numbers of patients with APS and may lead to acquired FXII deficiency.

Aging and word-finding: a comparison of spontaneous and constrained naming tests

This study compared the word-finding abilities of 26 young adults (ages 18-22 years), 26 young-old adults (ages 58-74 years), and 26 old-old adults (ages 75-93 years) on a confrontational naming test (Boston Naming Test) and a more spontaneous discourse test. The groups were matched in terms of gender (7 male, 19 female) and estimated IQ (M = 114). When participants were asked to narrate what they perceived in pictures (discourse test), the older adult groups committed significantly more word-retrieval errors than the younger adults. In contrast, results from the picture-naming test surprisingly revealed higher naming accuracy by the older adult groups. Subsequent examination of the picture-naming items revealed that four items appeared to be influenced by generational familiarity with the item. These results suggest that selection of cohort-free items for picture-naming tests is important when comparing across age-groups, and that tests of discourse may be better measures for assessing everyday word-finding difficulties in healthy older adults.

In vivo olanzapine occupancy of muscarinic acetylcholine receptors in patients with schizophrenia

Olanzapine is an atypical antipsychotic with potent antimuscarinic properties in vitro (K(i) = 2-25 nM). We studied in vivo muscarinic receptor occupancy by olanzapine at both low dose (5 mg/dy) and high dose (20 mg/dy) in several regions of cortex, striatum, thalamus and pons by analyzing [I-123]IQNB SPECT images of seven schizophrenia patients. Both low-dose and high-dose olanzapine studies revealed significantly lower [I-123]IQNB binding than that of drug-free schizophrenia patients (N = 12) in all regions except striatum. [I-123]IQNB binding was significantly lower at high-dose than low-dose in the same regions. Muscarinic occupancy by olanzapine ranged from 13% to 57% at 5 mg/dy and 26% to 79% at 20 mg/dy with an anatomical pattern indicating M(2) subtype selectivity. The [I-123]IQNB data indicate that olanzapine is a potent and subtype-selective muscarinic antagonist in vivo, perhaps explaining its low extrapyramidal side effect profile and low incidence of anticholinergic side effects.

A relationship between serotonin transporter genotype and in vivo protein expression and alcohol neurotoxicity

BACKGROUND

Genetic variation of the promoter for the serotonin transporter (5-HTT) gene has been associated with its functional capacity. In vitro, carriers of a short allele (s-carriers) of the 5-HTT promoter display significant reduction in 5-HTT capacity. Dysfunction of 5-HTT has been observed in alcoholic individuals. We assessed whether the allelic constitution of the 5-HTT gene is associated with reduced serotonin transporter availability among alcoholic individuals.

METHODS

We genotyped the 5-HTT promoter region and measured the availability of serotonin transporter protein with [I-123]beta-CIT SPECT in the raphe area in 14 abstinent male alcoholic subjects and 8 age-matched control subjects of European American descent.

RESULTS

Among control subjects, the ratio of in vivo 5-HTT availability for ll-homozygous individuals relative to s-carriers was comparable to serotonin uptake ratios measured in vitro. There was a significant interaction of diagnosis and 5-HTT promoter genotype on 5-HTT availability (p <.01). Among controls, ll-homozygous individuals displayed a significant increase as compared with s-carriers. The availability of raphe 5-HTT was significantly reduced in ll-homozygous alcoholic individuals and was negatively correlated with their amount of alcohol consumption. Among s-carriers, 5-HTT availability did not differ significantly between control and alcoholic subjects.

CONCLUSIONS

Our preliminary findings suggest an association between 5-HTT allelic constitution and in vivo measurements of human serotonin transporter availability, and a potentially selective susceptibility of ll-homozygous individuals to the neurotoxic effects of chronic excessive alcohol consumption.

Rising levels of cardiovascular mortality in Mississippi, 1979-1995

BACKGROUND

Cardiovascular disease rates are improving in the United States, but not for certain subgroups, especially some African Americans. The objective of the study is to assess current levels and trends in cardiovascular disease mortality in Mississippi.

METHODS

Mortality statistics from the U.S. vital statistics system for the period 1979-95 were used. Comparison of age-adjusted mortality rates in Mississippi with the other states for the year 1995 and with the nation as a whole over the period of 1979-95 was performed.

RESULTS

Mississippians had the highest age-adjusted cardiovascular disease morality rates in the nation in 1995. Overall, the cardiovascular rates in Mississippi were 37% higher than for the U.S. African American men and women from Mississippi had especially high cardiovascular mortality rates, approximately 50% and 70% higher than their white counterparts, respectively. The higher burden of cardiovascular disease in African Americans from Mississippi was especially marked in the younger age groups. Since about 1984-85, cardiovascular mortality rates in Mississippi have been increasing for African Americans, whereas nationally they have been decreasing. In contrast, cardiovascular mortality rates for whites in Mississippi have been declining, but at a much slower rate than seen nationally. The wide divergence in trends for African American and white men and women over that period in Mississippi has lead to an estimated 19,400 excess cardiovascular deaths. Virtually identical trends were found for heart disease.

CONCLUSIONS

Cardiovascular diseases are a major public health problem in Mississippi that is especially severe in African American residents, and the problem is growing worse each year. It is important to identify the determinants of and solutions for this enormous public health problem in Mississippi.