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Biomedical subjects

K K Wu

Publications and source records attributed to K K Wu.

At least 37 records · Page 2Linked to original sources
PubMed2001

Cross-sectional association of soluble thrombomodulin with mild peripheral artery disease; the ARIC study. Atherosclerosis Risk in Communities.

Thrombomodulin, an endothelial membrane glycoprotein, is an essential part of the protein C anti-coagulant pathway. It may also have a role in the regulation of fibrinolysis. We carried out a cross-sectional study to assess the association of soluble thrombomodulin (sTM) with peripheral artery disease (PAD) in a stratified random sample (n=863) of otherwise healthy black and white participants of the Atherosclerosis Risk in Communities (ARIC) Study. PAD was more common in black than in white participants and associated with classical risk factors in an expected manner; positively with age, smoking, hypertension, diabetes (P=0.05), and LDL-cholesterol, and inversely with HDL-cholesterol. Significant positive associations were observed also with fibrinogen and white blood cell count. Overall, the sTM concentration was not a significant predictor of PAD. The association was, however, modified by the level of factor VIII:C in whites (P=0.002 for the interaction), but not in blacks. Protein C was inversely associated with PAD prevalence (odds ratio 0.33, 95% CI 0.18--0.61, P=0.0004). sTM was inversely associated with plasminogen, but no associations with t-PA, PAI-1, or D-dimer were seen. In conclusion, the present results provide some additional evidence on the role of thrombomodulin-protein C pathway in atherosclerotic disease and support our earlier observation on interaction between sTM and factor VIII:C.

Black or African American↗
PubMed2001

Poly(ethylenimine)-mediated gene delivery affects endothelial cell function and viability.

Poly(ethylenimine) (PEI) was used to transfect the endothelial cell line EA.hy 926, and the secreted levels of three gene products, tissue-type plasminogen activator (tPA), plasminogen activator inhibitor type 1 (PAI-1), and von Willebrand Factor (vWF), were assessed via ELISA. We found that the levels of these gene products in cell supernatants increased by factors up to 16.3 (tPA), 8.3 (PAI-1), or 6.7 (vWF) times the levels recorded for untreated cells, and roughly correlated with the percentage of cells that expressed the reporter plasmid. Transfections carried out using promotorless constructs of the same reporter plasmid also yielded increases in tPA, PAI-1, and vWF to similar extents. Additionally, data regarding cell viability were gathered and found to inversely relate to both the effectiveness of the PEI used for transfection and the secreted levels of the three mentioned products. There appeared to be two distinct types of cell death, resulting from the use of either free PEI (which acts within 2 h) or PEI/DNA complexes (which cause death 7-9 h after transfection). Cells were also transfected by poly(L-lysine) and liposomal carriers, and increases in secreted tPA similar to those seen with PEI-mediated transfection were observed for positively transfected cells. The results of these investigations indicate that non-viral gene delivery can induce a state of endothelial cell dysfunction, and that PEI-mediated transfection can lead to two distinct types of cell death.

Cell Line↗
PubMed2001

Beta-fibrinogen gene -455G/A polymorphism and coronary heart disease incidence: the Atherosclerosis Risk in Communities (ARIC) Study.

PURPOSE: The -455G/A (HaeIII) polymorphism of the beta-fibrinogen gene influences levels of plasma fibrinogen. We determined whether it influences risk of coronary heart disease. METHODS: We conducted a case-cohort study nested within a prospective investigation, the Atherosclerosis Risk in Communities Study. We accumulated 398 incident coronary heart disease cases over a median of 5.3 years of follow-up and compared their -455G/A status with a random sample of the cohort (n = 498). RESULTS: Plasma fibrinogen was higher (p = 0.04) in AA homozygous participants (341 mg/dL) than in persons carrying the G allele: GA (290 mg/dL), GG (298 mg/dL). However, there was no significant association between -455G/A and incident CHD. CONCLUSIONS: Although a small effect cannot be excluded, -455G/A does not appear to be an important genetic determinant of CHD.

Adenine↗
PubMed2001

Aspirin and salicylate bind to immunoglobulin heavy chain binding protein (BiP) and inhibit its ATPase activity in human fibroblasts.

Salicylic acid (SA), an endogenous signaling molecule of plants, possesses anti-inflammatory and anti-neoplastic actions in human. Its derivative, aspirin, is the most commonly used anti-inflammatory and analgesic drug. Aspirin and sodium salicylate (salicylates) have been reported to have multiple pharmacological actions. However, it is unclear whether they bind to a cellular protein. Here, we report for the first time the purification from human fibroblasts of a approximately 78 kDa salicylate binding protein with sequence identity to immunoglobulin heavy chain binding protein (BiP). The Kd values of SA binding to crude extract and to recombinant BiP were 45.2 and 54.6 microM, respectively. BiP is a chaperone protein containing a polypeptide binding site recognizing specific heptapeptide sequence and an ATP binding site. A heptapeptide with the specific sequence displaced SA binding in a concentration-dependent manner whereas a control heptapeptide did not. Salicylates inhibited ATPase activity stimulated by this specific heptapeptide but did not block ATP binding or induce BiP expression. These results indicate that salicylates bind specifically to the polypeptide binding site of BiP in human cells that may interfere with folding and transport of proteins important in inflammation.

Adenosine Triphosphatases↗
PubMed2001

COX-2 expression and cell cycle progression in human fibroblasts.

Cyclooxygenase-2 (COX-2) is continuously expressed in most cancerous cells where it appears to modulate cellular proliferation and apoptosis. However, little is known about the contribution of transient COX-2 induction to cell cycle progression or programmed cell death in primary cells. In this study we determined whether COX-2 regulates proliferation or apoptosis in human fibroblasts. COX-2 mRNA, protein, and prostaglandin E2 (PGE2) were not detected in quiescent cells but were expressed during the G0/G1 phase of the cell cycle induced by serum. Inhibition of COX-2 did not alter G0/G1 to S phase transition or induce apoptosis at concentrations that diminished PGE2. Addition of interleukin-1beta to serum enhanced COX-2 expression and PGE2 synthesis over that by serum alone but had no effect on the progression of these cells into S phase. Furthermore, platelet-derived growth factor drove the G0 fibroblasts into the cell cycle without inducing detectable levels of COX-2 or PGE2. Collectively, these data show that transient COX-2 expression in primary human fibroblasts does not influence cell cycle progression.

Apoptosis↗
PubMed2001

Association of hemostatic variables with MRI-detected cerebral abnormalities: the atherosclerosis risk in communities study.

OBJECTIVES: Population-based and clinical prospective studies have shown independent associations of several hemostatic factors with ischemic heart disease and stroke. MRI-detected cerebral infarcts and white matter lesions are often detected in elderly individuals without clinical disease. It has been hypothesized that these types of lesions are often the consequence of cerebral ischemic damage and may be the precursors of clinical stroke. METHODS: This study examined the relation between a range of hemostatic factors measured at baseline in middle-aged participants who were free of diagnosed cardiovascular disease in the Atherosclerosis Risk in Communities Study and MRI-detected cerebral abnormalities at a 6-year follow-up examination. RESULTS: Plasma fibrinogen and perhaps von Willebrand factor were associated positively, and protein C was associated negatively, with cerebral infarctions. Adjusted for other risk factors, the odds ratio for cerebral infarction was 1.21 (95% confidence interval, CI = 1.02-1.44) per standard deviation increment for fibrinogen, 1.15 (95% CI = 0.97-1.37) per standard deviation increment for von Willebrand factor, and 0.77 (95% CI = 0.62-0.95) per standard deviation increment for protein C. No hemostatic factor, however, was associated with white matter disease. CONCLUSIONS: This study has only a follow-up MRI, and it is likely that some MRI lesions were present at baseline. Nevertheless, increased levels of fibrinogen and von Willebrand factor and reduced levels of protein C appear to be associated with cerebral infarction identified by MRI.

Aged↗
PubMed2001

Prospective study of fibrinolytic factors and incident coronary heart disease: the Atherosclerosis Risk in Communities (ARIC) Study.

The fibrinolytic system may play a role in the pathogenesis of coronary heart disease (CHD), but existing prospective studies have not consistently shown an independent association between fibrinolytic factors and CHD. None has reported an association between plasminogen and CHD incidence. In the prospective Atherosclerosis Risk in Communities (ARIC) Study of middle-aged adults, we examined the association of incident CHD with several fibrinolytic factors: tissue plasminogen activator antigen, plasminogen activator inhibitor-1, plasminogen, and fibrin fragment D-dimer as well as a marker of coagulation activation (prothrombin fragment F1.2). We measured these in stored baseline plasma samples of 326 subjects who developed CHD and, for comparison, a stratified random sample of the entire cohort (n=720). Tissue plasminogen activator and plasminogen activator inhibitor-1 antigen levels were associated positively with CHD incidence in analyses adjusted for age, race, and sex but were not associated with CHD after adjustment for other risk factors. Plasminogen and D-dimer levels were associated positively and independently with CHD incidence; the multivariable-adjusted relative risks (95% CIs) for the highest versus lowest quintiles were 2.20 (1.2 to 4.2) for plasminogen and 4.21 (1.9 to 9.6) for D-dimer. F1.2 was not associated with CHD incidence. Our findings lend support for a link between fibrinolytic factors and CHD incidence. A positive association between plasminogen and CHD is seemingly opposite the direction expected but may reflect a compensatory response to impaired plasminogen activation in subjects prone to CHD.

Biomarkers↗
PubMed2001

Phase I trial of the angiogenesis inhibitor TNP-470 for progressive androgen-independent prostate cancer.

Clinical and laboratory observations support the view that angiogenesis is necessary for prostate cancer progression. The angiogenesis inhibitor TNP-470 has demonstrated in vivo antitumor activity in a series of clinical models. To evaluate a possible therapeutic clinical value, we conducted a Phase I dose escalation trial of alternate-day i.v. TNP-470 in 33 patients with metastatic and androgen-independent prostate cancer. The patients were evaluated during therapy for evidence of neurological toxic effects. An assay of endothelial and vascular proliferation "markers" and a sequential assay of serum prostate-specific antigen concentration were performed. The effects of TNP-470 could be evaluated in 32 of the 33 patients. The maximum tolerated dose was 70.88 mg/m(2) of body surface area. The dose-limiting toxic effect was a characteristic neuropsychiatric symptom complex (anesthesia, gait disturbance, and agitation) that resolved upon cessation of therapy. The times to clinical recovery of neurological side effects were 6, 8, and 14 weeks. No definite antitumor activity of TNP-470 was observed; however, transient stimulation of the serum prostate-specific antigen concentration occurred in some of the patients treated. Additional studies of TNP-470 should be conducted using an alternate-day i.v. injection of 47.25 mg/m(2) body surface area and should focus on understanding and overcoming the neurological toxic effects. In addition, valid intermediate end points that reflect the status of tumor-associated neovascularity are needed to facilitate effective development of treatment strategies.

Aged↗
PubMed2000

Cell cycle-dependent expression of cyclooxygenase-2 in human fibroblasts.

The purpose of this investigation is to determine whether the levels of cyclooxygenase-2 (COX-2) expression are cell cycle dependent. We used a serum-starved human foreskin fibroblast model to determine changes in COX-2 mRNA, protein, and promoter activity in response to stimulation with interleukin-1b (IL-1b) and phorbol 12-myristate 13-acetate (PMA) at G0, G1, S and G2/M phases of the cell cycle. IL-1b (1 ng/ml) and PMA (100 nM) induced robust COX-2 expression in the G0 cells, and the level of COX-2 expression declined progressively after the cells had entered the cell cycle. The COX-2 mRNA level at G1, S and G2/M phases of the cell cycle was 76%, 46%, and 30% of that at G0, respectively. A 5-flanking promoter fragment of COX-2 constructed into a luciferase expression vector was transfected into cells. The promoter activity in response to PMA stimulation was significantly higher in G0 than in S phase cells. These results imply that G0 cells are the key players in inflammation and other COX-2-dependent pathophysiological processes. When the cells are in the proliferative phase, COX-2 inducibility becomes restrained probably by an endogenous control mechanism to avoid COX-2 mediated oxidative DNA damage.

Cell Cycle↗
PubMed2000

Platelet Pl(A2) allele and incidence of coronary heart disease: results from the Atherosclerosis Risk In Communities (ARIC) Study.

BACKGROUND: The major platelet integrin glycoprotein IIb-IIIa plays a primary role in platelet aggregation and acute thrombus formation at the site of vascular injury. A genetic polymorphism of glycoprotein IIb-IIIa (Pl(A)) has recently been proposed as a potential genetic factor linking to platelet hyperaggregability and increased risk of myocardial infarction. Despite numerous, mostly nonprospective studies, the role of this polymorphism as a clinically relevant, inherited risk factor for coronary heart disease (CHD) is still controversial. The purpose of this study was to determine whether Pl(A2) is a risk factor for incident CHD and whether it is correlated with increased platelet activation in a case-cohort study nested within a prospective epidemiologic investigation. METHODS AND RESULTS: Blood samples were collected and processed from the Atherosclerosis Risk in Communities Study cohort at the baseline examination (1987 to 1989). They were stored at -80 degrees C. Pl(A1/A2) genotype and plasma beta-thromboglobulin levels were determined in 439 incident CHD cases and a reference cohort sample of 544 (of whom 18 were also CHD cases). The prevalence of the Pl(A2) allele was not different in cases versus noncases. No significant correlation between CHD risk factors and the Pl(A2) allele was noted either. Platelet activation, as measured by plasma beta-thromboglobulin levels, was not enhanced in individuals with the Pl(A2) allele. CONCLUSIONS: This prospective study indicates that healthy individuals carrying the Pl(A2) allele do not have an increased risk of CHD.

Alleles↗
PubMed2000

Poly(ethylenimine)-mediated transfection: a new paradigm for gene delivery.

Poly(ethylenimine) (PEI) is a synthetic polycation that has been used successfully for gene delivery both in vitro and in vivo due, in theory, to a form of protection that is afforded to the carried plasmids. In this study the stability of PEI/DNA complexes was demonstrated using deoxyribonuclease (DNase) 1 and DNase 2, various levels of pH, and increasing exposure times. DNA that was complexed with PEI was not degraded when exposed to at least 25 Units of either enzyme for 24 h while uncomplexed forms of the same plasmid were digested when exposed to 0.010 Units of DNase 1 for 0.05 h or 0. 003 Units of DNase 2 for 1 h. For further comparison, the stability of complexes made with poly(L-lysine) (PLL) and DNA was examined and found to be lower than that of PEI/DNA complexes; PLL-complexed DNA was digested on exposure to 1.25 Units of DNase 1 for 3 min. Cells were transfected with PEI/DNA complexes and, by using a pH indicator and optical recording techniques, it was found that the normal lysosomal pH value of 5.0 was not altered, bringing into question PEI's hypothesized lysosomal entry. Confocal microscopy showed that PEI/DNA complexes and lysosomes do not merge during transfection (although PLL/DNA complexes do). The lack of lysosomal involvement in PEI-mediated transfection is surprising because it goes against the conventional wisdom that has attempted to explain how PEI functions during transfection. PEI forms a stable complex with DNA, which moves from endocytosis to nuclear entry without significant cellular obstacles.

Animals↗
PubMed2000

Colocalization of prostacyclin synthase with prostaglandin H synthase-1 (PGHS-1) but not phorbol ester-induced PGHS-2 in cultured endothelial cells.

The subcellular colocalization of prostacyclin synthase (PGIS) with prostaglandin H synthase (PGHS) has not been delineated. To test the hypothesis that its colocalization with PGHS is crucial for prostacyclin synthesis, we determined subcellular locations of PGIS, PGHS-1, and PGHS-2 in bovine aortic endothelial cells by immunofluorescent confocal microscopy. PGIS and PGHS-1 were colocalized to nuclear envelope (NE) and endoplasmic reticulum (ER) in resting and adenovirus-infected bovine aortic endothelial cells. PGIS and PGHS-2 were also colocalized to ER in serum-treated or adenovirus-cyclooxygenase-2-infected cells. By contrast, PGIS was not colocalized with PGHS-2 in cells induced with phorbol 12-myristate 13-acetate where PGHS-2 was visualized primarily in vesicle-like structures. The lack of colocalization was accompanied by failed prostacyclin production. Resting ECV304 cells did not produce prostacyclin and had no detectable PGHS-1 and PGIS proteins. Confocal analysis showed abnormal colocalization of PGIS and PGHS-1 to a filamentous structure. Interestingly, the abundant PGIS and PGHS-1 expressed in adenovirus-infected ECV304 cells were colocalized to NE and ER, which synthesized a large quantity of prostacyclin. These findings underscore the importance of colocalization of PGHS and PGIS to ER and NE in prostacyclin synthesis.

Animals↗
PubMed2000

Characterization of the roles of the 594-645 region in human endothelial nitric-oxide synthase in regulating calmodulin binding and electron transfer.

It has been postulated that a segment (residues 594-645) inserted in the FMN subdomain of human endothelial nitric-oxide synthase (eNOS) plays a crucial role in controlling Ca(2+)-dependent CaM binding for eNOS activity. To investigate its functions, we expressed human eNOS in a baculovirus system with deletion of a 45-residue segment from this region (residues 594-606 and 614-645, designated as Delta45eNOS), and characterized the purified mutant enzyme. In contrast with wild-type eNOS, Delta45eNOS exhibited characteristics resembling inducible NOS (iNOS). It contained an endogenously bound CaM, which was essential in folding and stabilizing this mutant enzyme, and retained 60% of L-citrulline formation in 5 mM EGTA. We also produced four N-terminally truncated reductase domains with or without the 45-residue segment, and either including or excluding the CaM-binding sequence. Basal cytochrome c reductase activity of reductase domains without the 45-residue segment was up to 20 fold greater than that of corresponding insert-containing domains, and higher than CaM-stimulated activity of the wild-type enzyme. A series of mutants with smaller fragment deletion in this region such as Delta594-604, Delta605-612, Delta613-625, Delta626-634, Delta632-639, and Delta640-645 mutants were further characterized. The crude lysate of mutants Delta613-625 and Delta632-639 did not show activity in the presence of Ca(2+)/CaM, while other four mutants had activity comparable to that of WTeNOS. The purified Delta594-604 and Delta605-612 proteins had a 3-5-fold higher affinity for Ca(2+)/CaM, but their L-citrulline forming activity was still 80% dependent upon the addition of Ca(2+)/CaM. Both mutants exhibited a low level of the cytochrome c and ferricyanide reductase activities, which either did not respond to (Delta594-604) or slightly enhanced by (Delta605-612) the exogenous CaM. In contrast, activities of Delta626-634 and Delta640-645 like those of WTeNOS were largely Ca(2+)/CaM-dependent. Thus, our findings indicate that the N-terminal half of the 594-645 segment containing residues 594-612 plays a significant role in regulating Ca(2+)/CaM binding.

Amino Acid Sequence↗
PubMed2000

Haemostasis and carotid artery wall thickness in non-insulin dependent diabetes mellitus.

The purpose of this study was to examine the associations of carotid artery intima-media wall thickness (IMT) with hemostatic proteins and cardiovascular risk factors (CVRFs) in participants with and without non-insulin dependent diabetes mellitus (NIDDM). IMT measurements were determined by high resolution B-mode ultrasound imaging of the carotid arteries in 921 participants with NIDDM and 11,964 non-diabetic participants aged 45-64 years. Fasting glucose, serum lipids and activated partial thromboplastin time, factor VIII fibrinogen, factor VII, antithrombin III, protein C, and von Willebrand factor measurements were made. Compared to non-diabetic participants, participants with NIDDM had a more adverse pattern of CVRFs and a more procoagulatory profile. Participants with NIDDM had 0.06 mm (8.1%) higher mean IMT compared to non-diabetic participants after adjusting for age and gender (P < 0.001). However, only plasma fibrinogen concentrations showed statistically significant positive associations with IMT in both groups. After adjusting for CVRFs and fibrinogen, mean IMT remained 0.04 mm (5.4%) higher in diabetic compared to non-diabetic participants. Despite the more procoagulatory profile in participants with NIDDM, only plasma fibrinogen concentrations were independently associated with mean IMT. The association of NIDDM with mean IMT was only partly explained by CVRFs.

Age Distribution↗
PubMed2000

Morton neuroma and metatarsalgia.

Morton neuroma is most likely a mechanically-induced degenerative neuropathy that predilects the third common digital nerve in middle-aged women who frequently wear fashionable shoes that are not designed for the physiology of the foot. A compression test of the affected web space is quite specific for its diagnosis, and an ultrasonograph can tell its exact size. If conservative means fail to relieve the painful symptoms of a Morton neuroma, surgical removal can produce dramatic pain relief. Metatarsalgia means pain in the metatarsal head region, and exists in three general forms: metatarsalgia of the first metatarsal head region, metatarsalgia of the fourth lateral metatarsal head region, and generalized metatarsalgia. There are numerous causes of metatarsalgia; a selected and important group of causes is discussed in this article. When conservative means fail to relieve metatarsalgia, specific surgical operations are quite effective for relief of pain, and are briefly described in the text.

Female↗
PubMed2000

Shear stress differentially regulates PGHS-1 and PGHS-2 protein levels in human endothelial cells.

The secretion of prostacyclin (PGI2) by endothelial cells is regulated by shear stress. Prostaglandin H synthase (PGHS) is considered to be a key limiting enzyme in the synthesis of PGI2 from arachidonic acid. Endothelial cells were cultured in the presence of 4, 15, or 25 dyn/cm2 shear stress using a parallel plate flow chamber to assess the effect of shear stress on both PGHS isoforms, PGHS-1 and PGHS-2. In cells exposed to 4, 15, or 25 dyn/cm2 shear stress PGHS-1 and PGHS-2 protein levels initially decreased. The decrease was followed by a sustained increase for PGHS-1 but only a transient increase for PGHS-2. The duration of the PGHS-2 increase depended on the magnitude of the shear stress. The effect of altering shear stress levels on PGHS protein levels in cells preconditioned to either 4, 15, or 25 dyn/cm2 shear stress for 48 h was also studied. Changing shear stress levels effected PGHS-2 but not PGHS-1. Increases in shear stress levels from 4 to 15 or 25 dyn/cm2 caused a decrease in PGHS-2. In contrast, decreases in shear stress levels from 15 or 25 to 4 dyn/cm2 caused PGHS-2 to increase. There was a continual decrease in PGHS-2 when the shear stress was changed from 15 to 25 or 25 to 15 dyn/cm2. In summary, the regulation of PGHS-2 by shear stress is dependent upon the magnitude of the shear stress, whereas the regulation of PGHS-1 protein levels seems to be independent of the shear stress magnitude. The regulation of PGHS-1 and PGHS-2 protein levels by shear stress indicates that these proteins play an important role in the maintenance of cardiovascular homeostasis as regulators of PGI2 production.

Blotting, Western↗
PubMed2000

Determinants of population changes in fibrinogen and factor VII over 6 years: the Atherosclerosis Risk in Communities (ARIC) Study.

Although numerous cross-sectional studies have identified possible determinants of plasma fibrinogen and factor VII levels, few prospective studies exist. We assessed the longitudinal relation of changes in fibrinogen and factor VII over 6 years with changes to other cardiovascular risk factors in a sample of 440 men and 549 women from the Atherosclerosis Risk in Communities (ARIC) study. Fibrinogen increased more in older participants, those with or who developed diabetes, those who at any time smoked, and those whose plasma HDL cholesterol or triglycerides decreased and increased less in female participants who started hormonal replacement therapy. Factor VII coagulant activity increased more in younger participants, women, those who gained greater weight or developed diabetes, those who quit smoking, those in whom plasma triglycerides decreased, and female participants who received hormonal replacement therapy. Thus, our longitudinal data suggest with some exceptions that adverse changes in cardiovascular risk factors are accompanied by increases in plasma levels of fibrinogen and factor VII.

Aging↗