Platelet glycoprotein IIIa Pl(a) polymorphism, fibrinogen, and platelet aggregability: The Framingham Heart Study

BACKGROUND

Recent data suggest that the Pl(A2) allele of the platelet glycoprotein IIIa receptor may be a genetic risk factor for cardiovascular disease. We previously reported that the Pl(A2) allele was associated with increased platelet aggregability, as indicated by lower epinephrine threshold concentrations. Paradoxically, however, it has been reported that Pl(A2)-positive platelets have reduced fibrinogen binding. Because fibrinogen mediates platelet aggregability, we hypothesized that plasma fibrinogen levels may interact with Pl(A) genotype in modulating platelet aggregability. Methods and Results-- Glycoprotein IIIa Pl(A) genotype, fibrinogen level, and platelet aggregability were ascertained in 1340 subjects enrolled into the Framingham Offspring Study. Platelet aggregability was evaluated by the Born method. Higher fibrinogen levels were associated with increased epinephrine-induced aggregation (P=0.002) and a trend for ADP-induced aggregation (P=0.07). The fibrinogen effect was genotype specific, however, in that the increase in platelet aggregability with higher fibrinogen was present for the Pl(A1/A1) genotype (P=0.0005 and P=0.03 for epinephrine- and ADP-induced aggregation, respectively) but not for the Pl(A2)-positive genotype (P>0.90).

CONCLUSION

Higher fibrinogen levels were associated with increased platelet aggregability. However, the association between fibrinogen and platelet aggregability was genotype specific. This interaction may be responsible for the conflicting findings regarding Pl(A) genotype and platelet aggregability. Further study of this gene-environment interaction may provide insight into cardiovascular disease risk.

Genetic and environmental contributions to platelet aggregation: the Framingham heart study

BACKGROUND

Platelet aggregation plays an important role in arterial thrombosis in coronary heart disease, stroke, and peripheral arterial disease. However, the contribution of genetic versus environmental influences on interindividual variation in platelet aggregability is poorly characterized.

METHODS AND RESULTS

We studied the heritability of platelet aggregation responses in 2413 participants in the Framingham Heart Study. The threshold concentrations of epinephrine and ADP required to produce biphasic platelet aggregation and collagen lag time were determined. Mixed-model linear regression was used to calculate correlation coefficients within sibships and within spouse pairs. Variance and covariance component methods were used to estimate the proportion of platelet aggregation attributable to measured covariates versus additive genetic effects. After accounting for environmental covariates, the adjusted sibling correlations for epinephrine, ADP, and collagen lag time were 0.24, 0.22, and 0.31, respectively (P=0.0001 for each). In contrast, adjusted correlations for spouse-pairs were -0.01, 0.05, and -0.02, respectively (all P>0.30). The estimated heritabilities were 0.48, 0.44, and 0.62, respectively. Measured covariates accounted for only 4% to 7% of the overall variance in platelet aggregation, and heritable factors accounted for 20% to 30%. The platelet glycoprotein IIIa Pl(A2) polymorphism and the fibrinogen Hind III beta-148 polymorphism contributed <1% to the overall variance.

CONCLUSIONS

In our large, population-based sample, heritable factors play a major role in determining platelet aggregation, and measured covariates play a lesser role. Future studies are warranted to identify the key genetic variants that regulate platelet function and to lay the groundwork for rational pharmacogenetic approaches.

The vesiculo-vacuolar organelle (VVO). A new endothelial cell permeability organelle

A newly defined endothelial cell permeability structure, termed the vesiculo-vacuolar organelle (VVO), has been identified in the microvasculature that accompanies tumors, in venules associated with allergic inflammation, and in the endothelia of normal venules. This organelle provides the major route of extravasation of macromolecules at sites of increased vascular permeability induced by vascular permeability factor/vascular endothelial growth factor (VPF/VEGF), serotonin, and histamine in animal models. Continuity of these large sessile structures between the vascular lumen and the extracellular space has been demonstrated in kinetic studies with ultrastructural electron-dense tracers, by direct observation of tilted electron micrographs, and by ultrathin serial sections with three-dimensional computer reconstructions. Ultrastructural enzyme-affinity cytochemical and immunocytochemical studies have identified histamine and VPF/VEGF bound to VVOs in vivo in animal models in which these mediators of permeability are released from mast cells and tumor cells, respectively. The high-affinity receptor for VPF/VEGF, VEGFR-2, was localized to VVOs and their substructural components by pre-embedding ultrastructural immunonanogold and immunoperoxidase techniques. Similar methods were used to localize caveolin and vesicle-associated membrane protein (VAMP) to VVOs and caveolae, indicating a possible commonality of formation and function of VVOs to caveolae.

A general algorithm for optimal sampling schedule design in nuclear medicine imaging

Optimal sampling schedule (OSS) is of great interest in biomedical experiment design, as it can improve the physiological parameter estimation precision and significantly reduce the samples required. A number of well designed algorithms and software packages have been developed, which deal with the instantaneous measurements at discrete times. However, in nuclear medicine tracer kinetic studies, the imaging systems, such as positron emission tomography (PET) and single photon emission computed tomography (SPECT), take measurements (images) based on continuous accumulation over time intervals. In this case, the existing algorithms cannot be used to design OSS so as to reduce the image frame numbers. In this paper, a general OSS design algorithm for the accumulative measurement is proposed. The potential usefulness of the algorithm is demonstrated by its designing OSS in [18F] fluoro-2-deoxy-D-glucose (FDG) studies with PET to estimate the local cerebral metabolic rate of glucose. The robustness of parameter estimation using the OSS with respect to intra-subject and inter-subject parameter variations is also presented.

Study on examinee's dose delivered in computed tomography

Dose profiles are presented resulting from computed tomography (CT). The profiles are positioned at the central axis, 1 cm away from the outer surface of the phantom, for single and multiple scans. A Hitachi W-1000 scanner is used with a thermoluminescent dosimeter (TLD), and standard dosimetry head and trunk phantoms. Regression equations are found linking the dose resulting from scattered radiation associated with a single scan to the distance from the scanning centre. The impact on the CT dose index value (CTDI) for varying integrating lengths is analysed. Some problems associated with CT dose measurement are noted, which may assist in the practical application of IBSS (International Basic Standard of Radiation Protection and Safety of Radiation Sources) guide levels.

Glomeruloid microvascular proliferation follows adenoviral vascular permeability factor/vascular endothelial growth factor-164 gene delivery

Glomeruloid bodies are a defining histological feature of glioblastoma multiforme and some other tumors and vascular malformations. Little is known about their pathogenesis. We injected a nonreplicating adenoviral vector engineered to express vascular permeability factor/vascular endothelial growth factor-164 (VPF/VEGF(164)) into the ears of athymic mice. This vector infected local cells that strongly expressed VPF/VEGF(164) mRNA for 10 to 14 days, after which expression gradually declined. Locally expressed VPF/VEGF(164) induced an early increase in microvascular permeability, leading within 24 hours to edema and deposition of extravascular fibrin; in addition, many pre-existing microvessels enlarged to form thin-walled, pericyte-poor, "mother" vessels. Glomeruloid body precursors were first detected at 3 days as focal accumulations of rapidly proliferating cells in the endothelial lining of mother vessels, immediately adjacent to cells expressing VPF/VEGF(164). Initially, glomeruloid bodies were comprised of endothelial cells but subsequently pericytes and macrophages also participated. As they enlarged by endothelial cell and pericyte proliferation, glomeruloid bodies severely compromised mother vessel lumens and blood flow. Subsequently, as VPF/VEGF(164) expression declined, glomeruloid bodies devolved throughout a period of weeks by apoptosis and reorganization into normal-appearing microvessels. These results provide the first animal model for inducing glomeruloid bodies and indicate that VPF/VEGF(164) is sufficient for their induction and necessary for their maintenance.

Ultrastructural localization of vesicle-associated membrane protein(s) to specialized membrane structures in human pericytes, vascular smooth muscle cells, endothelial cells, neutrophils, and eosinophils

Vesicle-associated membrane proteins (VAMPs) are important to the trafficking of vesicles between membrane-bound intracytoplasmic organelles, in the facilitation of neurosecretion, and in constitutive and regulated secretion in non-neuronal cells. We used a pre-embedding ultrastructural immunonanogold method to localize VAMPs to subcellular sites in human cells of five lineages known to have cytoplasmic vesicles that may function in vesicular transport. We found VAMPs localized to caveolae in pericytes, vascular smooth muscle cells, and endothelial cells of venules, to the vesiculo-vacuolar organelle, recently defined in venular endothelial cells, to the vesicle-rich intergranular cytoplasm and secretory granule membranes of neutrophils, and to perigranular cytoplasmic secretory vesicles and secretory granule membranes in eosinophils. These specific localizations in five human vascular and granulocyte lineages support the notion that VAMPs have vesicle-associated functions in these cells.

Simultaneous estimation of physiological parameters and the input function--in vivo PET data

Dynamic imaging with positron emission tomography (PET) is widely used for the in vivo measurement of regional cerebral metabolic rate for glucose (rCMRGlc) with [18F]fluorodeoxy-D-glucose (FDG) and is used for the clinical evaluation of neurological disease. However, in addition to the acquisition of dynamic images, continuous arterial blood sampling is the conventional method to obtain the tracer time-activity curve in blood (or plasma) for the numeric estimation of rCMRGlc in mg glucose/100-g tissue/min. The insertion of arterial lines and the subsequent collection and processing of multiple blood samples are impractical for clinical PET studies because it is invasive, has the remote, but real potential for producing limb ischemia, and it exposes personnel to additional radiation and risks associated with handling blood. In this paper, based on our previously proposed method for extracting kinetic parameters from dynamic PET images, we developed a modified version (post-estimation method) to improve the numerical identifiability of the parameter estimates when we deal with data obtained from clinical studies. We applied both methods to dynamic neurologic FDG PET studies in three adults. We found that the input function and parameter estimates obtained with our noninvasive methods agreed well with those estimated from the gold standard method of arterial blood sampling and that rCMRGlc estimates were highly correlated (r = 0.973). More importantly, no significant difference was found between rCMRGlc estimated by our methods and the gold standard method (P > 0.16). We suggest that our proposed noninvasive methods may offer an advance over existing methods.

[Protective effect of c-fos antisense oligonucleotides on brain damage induced by glutamate]

OBJECTIVE

To investigate the relation between glutamate neurotoxicity and c-fos gene expression.

METHODS

c-fos antisense oligonucleotides (AS ODN) was injected into the right lateral ventricles of 9 SD rats to block the c-fos gene expression in brain tissue. c-fos sense oligonucleotides (S ODN) was used a control. The numbers and morphology of neurons in both cerebral cortex and hippocampal CA1 were detected by MIAS-300 image analysing instrument. c-fos gene expression in brain was observed by immunohistochemical method. The content of water and electrolytes in the brain tissue and Ca(2+) in the synapse were measured.

RESULTS

The c-fos AS ODN blocked the c-fos gene expression and reduced the content of both water and sodium in brain tissue and Ca(2+) in symptosome, thus alleviating the morphological damage in neuron. S ODN did not have such effect.

CONCLUSION

c-fos gene expression plays an important role in mediating the effect of glutamate neurotoxicity. Blocking the c-fos gene expression could antagonize glutamate neurotoxicity.

Hemostatic state and atrial fibrillation (the Framingham Offspring Study)

Atrial fibrillation (AF) is strongly associated with thromboembolic complications, although the mechanism for the increased risk has not been fully explained. To determine whether AF might be associated with a hypercoagulable state, we studied hemostatic factors in subjects with or without AF in the Framingham Heart Study. In 3,577 subjects, we measured fibrinogen, von Willebrand factor antigen, tissue plasminogen activator (tPA) antigen, and plasminogen activator inhibitor-1 antigen. Forty-seven subjects had AF at the index clinic examination and 15 had AF on a prior examination, but not on the current examination. Before matching, the 47 subjects with prevalent AF had higher levels of fibrinogen, von Willebrand factor, and tPA antigen than those without AF, all p < or =0.03. Compared with 167 referent subjects matched for age, sex, and other risk factors, those with AF had higher tPA antigen levels than those without AF, 1 1.8 +/- 4.0 ng/ml versus 10.5 +/- 3.9 ng/ml (p = 0.04). However, when further stratified according to their cardiovascular disease status, the differences in hemostatic factors were no longer significant. We conclude that the prothrombotic profile associated with AF was explained by the risk factors of the subjects and the presence of cardiovascular disease. Nonetheless, the hemostatic changes may contribute toward the propensity for thromboembolic complications in AF. Further prospective studies are needed to evaluate whether measurement of these and other hemostatic factors will identify patients with AF who are at increased risk for thromboembolic complications, and who may therefore benefit from more intensive therapy.

von Willebrand factor and retinal circulation in early-stage retinopathy of type 1 diabetes

OBJECTIVE

Although retinopathy is a common microvascular complication of type 1 diabetes, the mechanism for this complication is still unknown. Changes in retinal circulation have been noted before the development of overt retinal pathology. Because von Willebrand factor (vWF) is a marker for endothelial dysfunction and mediates platelet adhesion, we determined if there was an association between vWF and retinal circulation in the early stages of diabetic retinopathy.

RESEARCH DESIGN AND METHODS

Twenty subjects (aged 32.4 +/- 7.8 years) with type 1 diabetes and minimal or no retinopathy were studied. The mean duration of diabetes was 4.7 +/- 2.6 years. Data were collected at baseline and after 4 months of 1,800 IU vitamin E therapy or placebo. Retinal circulation was evaluated by video fluorescein angiography. Plasma vWF antigen levels were measured by enzyme-linked immunosorbent assay and fibrinogen by the Clauss method.

RESULTS

Retinal blood flow was negatively correlated with vWF levels (r = -0.44, P = 0.008), whereas retinal circulation time was positively correlated with vWF levels (r = 0.33, P = 0.048). Fibrinogen levels were not significantly associated with either retinal index. However, fibrinogen levels were positively associated with HbA1c levels (r = 0.34, P = 0.01), indicating an association between poor glycemic control and higher fibrinogen levels.

CONCLUSIONS

Increased vWF was associated with a prolonged retinal circulation time and reduced retinal blood flow in early-stage retinopathy of type 1 diabetes. Reduced blood flow associated with increased vWF levels may promote stasis in the retinal circulation and lead to local hypoxemia. These changes might contribute to the microvascular complications of diabetes. Whether the vWF levels predict retinal complications deserves further investigation.

Efficient and accurate numerical analysis of multilayer planar optical waveguides in lossy anisotropic media

This paper discusses a numerical method for computing the electromagnetic modes supported by multilayer planar optical waveguides constructed from lossy or active media, having in general a diagonal permittivity tensor. The method solves the dispersion equations in the complex plane via the Cauchy integration method. It is applicable to lossless, lossy and active waveguides, and to AntiResonant Reflecting Optical Waveguides (ARROW's). Analytical derivatives for the dispersion equations are derived and presented for what is believed to be the first time, and a new algorithm that significantly reduces the time required to compute the derivatives is given. This has a double impact: improved accuracy and reduced computation time compared to the standard approach. A different integration contour, which is suitable for leaky modes is also presented. Comparisons are made with results found in the literature; excellent agreement is noted for all comparisons made.

The effect of vitamin C supplementation on coagulability and lipid levels in healthy male subjects

Although dietary intake and plasma levels of vitamin C have been inversely associated with cardiovascular disease, the mechanism through which it may exert its effect has not been fully explained. Since thrombosis plays an important role in the onset of cardiovascular disease, we investigated the effect of vitamin C on measures of hemostasis that have been associated with cardiovascular risk. The effect of vitamin C on lipid levels was also evaluated. In a randomized, placebo-controlled, crossover study, we determined the effect of 2 g daily of vitamin C supplementation on platelet adhesion and aggregation, levels of tissue plasminogen activator antigen, plasminogen activator inhibitor, fibrinogen, plasma viscosity, von Willebrand factor, and lipid levels in 18 healthy male volunteers with low normal vitamin C levels. No striking effects of vitamin C on the hemostatic measures were observed, although tissue plasminogen activator antigen levels were inversely related to Vitamin C levels. Von Willebrand factor levels were slightly higher with vitamin C, although within the normal range. Total cholesterol levels were 10% lower when subjects were receiving vitamin C compared to placebo (167+/-7 mg/dL vs. 184+/-7 mg/dL), P=0. 007), although the total cholesterol/HDL ratio was not significantly different. Higher levels of tissue plasminogen activator antigen, which in the present study were associated with lower vitamin C levels, have been shown in prospective studies to convey an increased risk of cardiovascular events. Further studies of the effect of vitamin C on hemostatic measures are required in higher risk populations or those with known cardiovascular disease.

[Detection of K-ras gene mutations in DNA extracted from the plasma of patients with pancreatic cancer]

OBJECTIVES

To detect mutations of the K-ras codon 12 in DNA extracted from the plasma of patients with pancreatic cancer, and to explore the possibility of using this method in early diagnosis of pancreatic cancer.

METHODS

Plasma DNA was isolated from the blood of 22 patients with pancreatic cancer and from 20 normal controls. K-ras codon 12 mutations were detected by mutant enriched polymerase chain reaction-restriction fragment length polymorphism technique and subsequent product sequencing. The relation of K-ras mutations in plasma to clinical features in pancreatic cancer patients was analyzed.

RESULTS

Seventeen (77.3%) of 22 patients with pancreatic cancer had a codon 12 K-ras mutation in their plasma DNA. In two patients, the PCR products were sequenced and the mutations were confirmed. The occurrence of K-ras mutations in the plasma DNA was not related to tumor location, tumor size, and TNM stage. No K-ras mutation was detected in the plasma specimen of any of the normal controls.

CONCLUSIONS

K-ras mutations are frequently found in the plasma DNA of patients with pancreatic cancer. Analysis of K-ras mutation in the plasma DNA may be useful in the early detection of pancreatic cancer.

Identification of a PDZ-domain-containing protein that interacts with the scavenger receptor class B type I

The scavenger receptor class B type I (SR-BI) mediates the selective uptake of cholesteryl esters from high-density lipoprotein (HDL) and cholesterol secretion into bile in the liver. In this study, we identified an SR-BI-associated protein from rat liver membrane extracts by using an affinity chromatography technique. This protein of 523 amino acids contains four PDZ domains and associates with the C terminus of SR-BI by using its N-terminal first PDZ domain. Therefore, we denoted this protein as CLAMP (C-terminal linking and modulating protein). CLAMP was located mostly in the sinusoidal membranes, whereas SR-BI was detected in both sinusoidal and canalicular membranes. After the solubilization of the liver membranes with Triton X-100, SR-BI was immunoprecipitated with anti-CLAMP monoclonal antibody, suggesting the association of these proteins in vivo. By coexpressing SR-BI with CLAMP in Chinese hamster ovary cells, we observed (i) the increase in the expression level of SR-BI, (ii) the reduction in the deacylation rate of the cholesteryl esters taken up from HDL, and (iii) the change in the intracellular distribution of fluorescent lipid 1,1'-dioctadecyl-3,3, 3',3'-tetramethylindocarbocyanine percholate taken up from HDL. Taken together, these data suggest that CLAMP, a four-PDZ-domain-containing protein, is associated with SR-BI in the liver sinusoidal plasma membranes and may modulate the intracellular transport and metabolism of cholesteryl esters taken up from HDL.

[Spectrofluorometric trace determination of cerium(III) with ethylenediamintetraksi (methylphosphonic acid)]

Fluorescence of Ce(III) was greatly enhanced when Ce(III) forming 1:1 complex with ethylenediaminetetrakis (methylphosphonic acid)(EDTP) in solution of pH 7-8. The use of EDTP in the spectrofluorometric determination of trace amounts of cerium(III) ions is described. The apparent excitation and fluorescence wavelength are 313 and 397 nm, respectively. The fluorescence varies linearly with the concentration of cerium(III) in the range of 1 x 10(-8)-1 x 10(-4) mol.L-1, which is closed to the known best method. The quenching effects of some inorganic ions and other lanthanides are also investigated, which indicated that the method is superior to others in climinating the interfere of other ions, especially for Pr3+ and PO4(3-) ions.

[Study on relationship between apoptosis and proliferation of cells in liver cirrhosis and hepatocellular carcinoma]

Apoptosis and nuclear antigen of proliferating cells were detected by labelling technique of in situ terminal deoxynucleotide transferase and immunohistochemical method in liver cirrhosis and hepatocellular carcinoma(HCC). The density of apoptotic cells in HCC was significantly lower than that in cirrhosis, and the density of proliferating cells was much higher in HCC than that in cirrhosis. Apoptotic cells mainly distributed in the peripseudolobular region of cirrhosis and formed an apoptosis zone. But they scattered within the cancer tissue. The results suggest that the formation of apoptosis zone in cirrhosis may be related to the change of liver blood stream. Selective proliferation of cells may exist during carcinogenesis of liver cirrhosis.

Ultrastructural localization of the vascular permeability factor/vascular endothelial growth factor (VPF/VEGF) receptor-2 (FLK-1, KDR) in normal mouse kidney and in the hyperpermeable vessels induced by VPF/VEGF-expressing tumors and adenoviral vectors

Vascular permeability factor/vascular endothelial growth factor (VPF/VEGF) interacts with two high-affinity tyrosine kinase receptors, VEGFR-1 and VEGFR-2, to increase microvascular permeability and induce angiogenesis. Both receptors are selectively expressed by vascular endothelial cells and are strikingly increased in tumor vessels. We used a specific antibody to localize VEGFR-2 (FLK-1, KDR) in microvascular endothelium of normal mouse kidneys and in the microvessels induced by the TA3/St mammary tumor or by infection with an adenoviral vector engineered to express VPF/VEGF. A pre-embedding method was employed at the light and electron microscopic levels using either nanogold or peroxidase as reporters. Equivalent staining was observed on both the luminal and abluminal surfaces of tumor- and adenovirus-induced vascular endothelium, but plasma membranes at interendothelial junctions were spared except at sites connected to vesiculovacuolar organelles (VVOs). VEGFR-2 was also localized to the membranes and stomatal diaphragms of some VVOs. This staining distribution is consistent with a model in which VPF/VEGF increases microvascular permeability by opening VVOs to allow the transendothelial cell passage of plasma and plasma proteins.

[Genotype distribution of hepatitis C virus in hepatocellular carcinoma tissue in Hunan province]

Genotypes of hepatitis C virus(HCV) were detected by PCR using type-specific primer in 50 patients' hepatocellular carcinoma(HCC) tissue. The results showed that in the 50 HCC specimens, 30(60%) and 3(6%) were infected with the HCV type II and III, 5(10%) and 8(16%) with type II + III and type II + IV, 2(4%) with type II + I + III in combination, respectively. 2 cases were negative for HCV. These data suggest that HCV type II may be a predominant genotype related to hepatocarcinogenesis in Hunan Province, some cases of HCC may result from coinfection of HCV type II and other genotypes, and only few HCC be separately caused by infection of HCV type III.

Optimal image sampling schedule for both image-derived input and output functions in PET cardiac studies

Optimal sampling schedule (OSS) design for both image-derived input and output functions in tracer kinetic modeling with positron emission tomography (PET) is investigated. This problem is very important in noninvasive PET dynamic cardiac studies where both the input function, i.e., the plasma time-activity curve (PTAC), and the output function, i.e., the tissue time-activity curve (TTAC), are obtained simultaneously from the same sequence of PET images. The integral PET measurement is used in this study. The spillover correction for the cross contaminations in cardiac studies is incorporated into the OSS design procedure. A new target function based on the D-optimal criterion involving both the input and output sensitivity functions is proposed. The fluorodeoxyglucose (FDG) model and a six-parameter PTAC model are used to illustrate the simultaneous OSS design for both the PTAC and TTAC. An OSS design consisting of six different scanning intervals is derived. Computer simulations are performed based on the estimated parameters from real studies to evaluate the effectiveness of the OSS. The double modeling approach is used in parameter estimation to simultaneously estimate the parameters involved. The results have shown that, for a wide range of parameter variations, the OSS is as effective as a conventional sampling schedule (CSS) and comparable parameter estimates can be obtained. Compared with the use of the CSS, the use of the OSS leads to an approximately 70% reduction in the storage space and data processing time.

Factor VII gene polymorphism, factor VII levels, and prevalent cardiovascular disease: the Framingham Heart Study

Elevated factor VII levels have been associated with increased cardiovascular risk in some studies. The arginine/glutamine (Arg/Gln) polymorphism of the factor VII gene has been previously shown to modify factor VII levels. However, the presence of a gene/environment interaction on factor VII levels or a link with cardiovascular disease (CVD) remains uncertain. We studied subjects from the Framingham Heart Study to determine (1) the extent to which this genetic polymorphism affects factor VII levels; (2) whether interactions exist between this polymorphism and environmental factors on factor VII levels; and (3) the association between the polymorphism and CVD. Genotype data and factor VII antigen levels were available in 1816 subjects. Factor VII levels differed significantly among genotypes in an additive fashion: Gln homozygous, 82.7+/-2.5%; heterozygous, 92.2+/-0.7%; and Arg homozygous, 100. 5+/-0.4% (P<0.0001). The polymorphism was the strongest, single predictor of factor VII levels, explaining 7.7% of the total variance of factor VII levels, whereas other traditional risk factors combined explained an additional 11.5% of the variance. There was an interaction (P=0.02) between the genotype and total cholesterol on factor VII levels, such that the correlation coefficient and slope (factor VII level/total cholesterol) were greatest in Gln/Gln subjects. Among 3204 subjects characterized for genotype and CVD, there was no significant relationship between the genotype and CVD (P=0.12). In the Framingham Heart Study, the Arg/Gln polymorphism was significantly associated with factor VII antigen levels. The strength of the association suggests that genetic variation plays an important role in determining factor VII levels. However, despite being associated with factor VII levels, the Arg/Gln polymorphism was not associated with prevalent CVD.

Heterogeneity of the angiogenic response induced in different normal adult tissues by vascular permeability factor/vascular endothelial growth factor

Vascular permeability factor/vascular endothelial growth factor (VPF/VEGF) is an angiogenic cytokine with potential for the treatment of tissue ischemia. To investigate the properties of the new blood vessels induced by VPF/VEGF, we injected an adenoviral vector engineered to express murine VPF/VEGF164 into several normal tissues of adult nude mice or rats. A dose-dependent angiogenic response was induced in all tissues studied but was more intense and persisted longer (months) in skin and fat than in heart or skeletal muscle (< or =3 weeks). The initial response (within 18 hours) was identical in all tissues studied and was characterized by microvascular hyperpermeability, edema, deposition of an extravascular fibrin gel, and the formation of enlarged, thin-walled pericyte-poor vessels ("mother" vessels). Mother vessels developed from preexisting microvessels after pericyte detachment and basement membrane degradation. Mother vessels were transient structures that evolved variably in different tissues into smaller daughter vessels, disorganized vessel tangles (glomeruloid bodies), and medium-sized muscular arteries and veins. Vascular structures closely resembling mother vessels and each mother vessel derivative have been observed in benign and malignant tumors, in other examples of pathological and physiological angiogenesis, and in vascular malformations. Together these data suggest that VPF/VEGF has a role in the pathogenesis of these entities. They also indicate that the angiogenic response induced by VPF/VEGF is heterogeneous and tissue specific. Finally, the muscular vessels that developed from mother vessels in skin and perimuscle fat have the structure of collaterals and could be useful clinically in the relief of tissue ischemia.