bluuebunny/crossref_metadata_2025 huggingface dataset:
Respiratory muscle function and activation in chronic obstructive pulmonary disease
Authors: McKenzie David K. , Butler Jane E. , Gandevia Simon C.
Published: April 2009

Inspiratory muscles are uniquely adapted for endurance, but their function is compromised in chronic obstructive pulmonary disease (COPD) due to increased loads, reduced mechanical advantage, and increased ventilatory requirements. The hyperinflation of COPD reduces the flow and pressure-generating capacity of the diaphragm. This is compensated by a threefold increase in neural drive, adaptations of the chest wall and diaphragm shape to accommodate the increased volume, and adaptations of muscle fibers to preserve strength and increase endurance. Paradoxical indrawing of the lower costal margin during inspiration in severe COPD (Hoover's sign) correlates with high inspiratory drive and severe airflow obstruction rather than contraction of radially oriented diaphragm fibers. The inspiratory muscles remain highly resistant to fatigue in patients with COPD, and the ultimate development of ventilatory failure is associated with insufficient central drive. Sleep is associated with reduced respiratory drive and impairments of lung and chest wall function, which are exaggerated in COPD patients. Profound hypoxemia and hypercapnia can occur in rapid eye movement sleep and contribute to the development of cor pulmonale. Inspiratory muscles adapt to chronic loading with an increased proportion of slow, fatigue-resistant fiber types, increased oxidative capacity, and reduced fiber cross-sectional area, but the capacity of the diaphragm to increase ventilation in exercise is compromised in COPD. In COPD, neural drive to the diaphragm increases to near maximal levels in exercise, but it does not develop peripheral muscle fatigue. The improvement in exercise capacity and dyspnea following lung volume reduction surgery is associated with a substantial reduction in neural drive to the inspiratory muscles.
Absence of caspase-3 protects against denervation-induced skeletal muscle atrophy
Authors: Plant Pamela J. , Bain James R. , Correa Judy E. , Woo Minna , Batt Jane
Published: April 2009

The ubiquitin-proteasome system is a key proteolytic pathway activated during skeletal muscle atrophy. The proteasome, however, cannot degrade intact myofibrils or actinomyosin complexes. In rodent models of diabetes mellitus and uremia, caspase-3 is involved in actinomyosin cleavage, generating fragments that subsequently undergo ubiquitin-proteasome-mediated degradation. Here, we demonstrate that caspase-3 also mediates denervation-induced muscle atrophy. At 2 wk after tibial nerve transection, the denervated gastrocnemius of caspase-3-knockout mice weighed more and demonstrated larger fiber-type-specific cross-sectional area than the denervated gastrocnemius of wild-type mice. However, there was no difference between caspase-3-knockout and wild-type denervated muscles in the magnitude or pattern of actinomyosin degradation, as determined by Western blotting for actin and the 14-kDa actin fragment. Similarly, there was no difference between caspase-3-knockout and wild-type denervated muscles in the magnitude of increase in proteasome activity, total protein ubiquitination, or atrogin-1 and muscle-specific ring finger protein 1 transcript levels. In contrast, there was an increase in TdT-mediated dUTP nick end label-positive nuclei in the denervated muscle of wild-type compared with caspase-3-knockout mice. Apoptotic signaling upstream of caspase-3 remained intact, with equivalent mitochondrial Bax translocation and cytochrome c release and caspase-9 activation in the denervated gastrocnemius muscle of wild-type and caspase-3-knockout mice. In contrast, diminished poly(ADP-ribose) polymerase cleavage in the denervated muscle of caspase-3-knockout compared with wild-type mice revealed that apoptotic signaling downstream of caspase-3 was impaired, suggesting that the absence of caspase-3 protects against denervation-induced muscle atrophy by suppressing apoptosis as opposed to ubiquitin-proteasome-mediated protein degradation.
Artificial gravity maintains skeletal muscle protein synthesis during 21 days of simulated microgravity
Authors: Symons T. B. , Sheffield-Moore M. , Chinkes D. L. , Ferrando A. A. , Paddon-Jones D.
Published: April 2009

We sought to determine the effects of longitudinal loading (artificial gravity) on skeletal muscle protein kinetics in 15 healthy young males after 21 days of 6° head-down tilt bed rest [experimental treatment (Exp) group: n = 8, 31 ± 1 yr; control (Con) group; n = 7, 28 ± 1 yr, means ± SE]. On days 1 and 21 of bed rest, postabsorptive venous blood samples and muscle biopsies (vastus lateralis and soleus) were obtained during a 1-h pulse bolus infusion protocol (0 min, l-[ ring-13C6]phenylalanine, 35 μmol/kg; 30 min, l-[ ring-15N]phenylalanine, 35 μmol/kg). Outcome measures included mixed muscle fractional synthesis (FSR) and breakdown rates (FBR). The Exp group experienced 1 h of longitudinal loading (2.5G at the feet) via a short-radius centrifuge during each day of bed rest. Mixed muscle FSR in the Con group was reduced by 48.5% ( day 1, 0.081 ± 0.000%/h vs. day 21, 0.042 ± 0.000%/h; P = 0.001) in vastus lateralis after 21 days of bed rest, whereas the Exp group maintained their rate of protein synthesis. A similar but nonsignificant change in FSR was noted for the soleus muscle (Exp, −7%; Con, −22%). No changes in muscle protein breakdown were observed. In conclusion, 1 h of daily exposure to artificial gravity maintained the rate of protein synthesis of the vastus lateralis and may represent an effective adjunct countermeasure to combat the loss of muscle mass and functional during extended spaceflight.
Infected Hepatic and Renal Cysts: Differential Impact on Outcome in Autosomal Dominant Polycystic Kidney Disease
Authors: Suwabe Tatsuya , Ubara Yoshifumi , Higa Yasushi , Nakanishi Shohei , Sogawa Yoko , Nomura Kazufumi , Nishimura Hiroaki , Hoshino Jyunichi , Sawa Naoki , Katori Hideyuki , Takemoto Fumi , Nakamura Michio , Tomikawa Shinji , Hara Shigeko , Takaichi Kenmei
Published: April 2009

Background: Infected cysts are a frequent and serious complication of autosomal dominant polycystic kidney disease. Such infections are classified into those affecting hepatic cysts and those affecting renal cysts. The purpose of this study was to compare the clinical course of infected hepatic cysts with that of infected renal cysts in patients with autosomal dominant polycystic kidney disease. Methods: We analyzed 43 patients referred to us for additional treatment of severely infected cysts between January 2004 and December 2006. All patients who required further treatment in addition to antibiotic therapy were included. Results: Aspiration was performed in all 28 patients with infected hepatic cysts. As a result, 17 patients were cured, 4 remain under treatment, and 6 died. One patient was cured by partial hepatectomy. Among the 15 patients with renal cysts, aspiration was performed in 4 with identifiable infected cysts, while renal transcatheter arterial embolization after appropriate antibiotic therapy was performed in 11 without identifiable infected cysts. No patient developed recurrence. Conclusion: In patients with infected renal cysts, aspiration or renal transcatheter arterial embolization after appropriate antibiotic therapy was effective. Although aspiration was often effective in patients with infected hepatic cysts, a good outcome was less likely than in those with renal cysts.
Stroke in the Very Elderly: Hospital Care, Case Fatality and Disposition
Authors: Saposnik Gustavo , Black Sandra
Published: April 2009

Background: The worldwide growing number of older people represents a new phenomenon. Considering that the prevalence of stroke increases with age and higher life expectancy, the prevalence of stroke will likely rise in the next decade. However, limited information is available about the burden of stroke in individuals over 90. Methods: This is a subgroup analysis from a multicenter cohort study including individuals admitted with an ischemic stroke to a broad range of hospitals across Canada. Patients were identified from the Canadian Hospital Morbidity database (HMDB), which is a national database that contains patient-level sociodemographic, diagnostic and administrative information. Multivariable analysis was performed using logistic regression. Outcomes measures include risk-adjusted stroke fatality, ICU admissions, medical complications, length of hospital stay and discharge disposition. Results: Among 26,676 patients with ischemic stroke admitted to 606 hospitals, 2,015 (7.6%) were aged 90 years or older. Risk-adjusted fatality at discharge was 6.3% (age <69), 12.5% (age 70–79), 22.0% (age 80–89) and 36.1% (age ≥90) (p < 0.001). Patients aged 90 and over were more likely admitted on weekends (28.1 vs. 24.6; p < 0.001), and less likely to be admitted to the ICU (4.3 vs. 13.0%, p < 0.001) and discharged to their pre-stroke residence (39.9% for those over 90 vs. 57.3% for patients younger than 90, p < 0.001). In the multivariable analysis, nonagenarians and older were 5–8 times more likely to die after adjusting for covariates. Conclusion: In our study, stroke patients over 90 had higher risk-adjusted mortality, longer hospitalization, and were less likely to be discharged to their original place of residence. In view of these findings, strategies need to be implemented to facilitate equal access to specialized stroke care for the elderly.
C-Reactive Protein Is a Determinant of First-Ever Stroke: Prospective Nested Case-Referent Study
Authors: Andersson Jonas , Johansson Lars , Ladenvall Per , Wiklund Per-Gunnar , Stegmayr Birgitta , Jern Christina , Boman Kurt
Published: April 2009

Background and Purpose: C-reactive protein (CRP) is a determinant of stroke, but there are no prospective studies on CRP and first ischemic stroke divided into etiologic subtypes. Our primary aim was to study CRP as a determinant of ischemic stroke, classified according to Trial of ORG 10172 in Acute Stroke Treatment (TOAST) criteria, and intracerebral hemorrhage (ICH) in a prospective study. A secondary aim was to study the relationship between the 1444C>T polymorphism, plasma levels of CRP and stroke. Methods: The study was a prospective population-based case-referent study nested within the Northern Sweden Cohorts. We defined 308 cases of ischemic stroke and 61 ICH. Two controls for each case were defined from the same cohort. Results: The OR for the highest (>3 mg/l) versus lowest group (<1 mg/l) of CRP was 2.58 (95% CI 1.74–3.84) for ischemic stroke and 1.63 (95% CI 0.67–3.93) for ICH. In a multivariate model including traditional risk factors, CRP remained associated with ischemic stroke (OR 2.06; 95% CI 1.29–3.29). Small-vessel disease was associated with CRP in the multivariate model (OR 3.88; 95% CI 1.10–13.7). The CRP 1444 (CC/CT vs. TT) polymorphism was associated with plasma levels of CRP but neither with ischemic stroke nor with ICH. Conclusions: This prospective population-based study shows that CRP is significantly associated with the risk of having a first ischemic stroke, especially for small-vessel disease. No significant associations were found between the CRP 1444C>T polymorphism and any stroke subtype.
Cerebrovascular Ischemic Events in HIV-1-Infected Patients Receiving Highly Active Antiretroviral Therapy: Incidence and Risk Factors
Authors: Corral Iñigo , Quereda Carmen , Moreno Ana , Pérez-Elías María-Jesús , Dronda Fernando , Casado José-Luis , Muriel Alfonso , Masjuán Jaime , Alonso-de-Leciñana María , Moreno Santiago
Published: April 2009

Background: Stroke risk is increased in AIDS patients, and highly active antiretroviral therapy (HAART) may accelerate atherosclerosis, but little is known about the incidence and risk factors for ischemic stroke in patients under HAART. We have studied the incidence, types of stroke and possible risk factors for cerebrovascular ischemic events in a large cohort of HIV-1-infected patients treated with HAART. Methods: We conducted a retrospective review of ischemic strokes and transient ischemic attacks occurring in a cohort of HIV-1-infected patients treated with HAART from 1996 to 2008. As a control group, consecutive unselected patients from the same cohort were included. Patients and controls were compared for demographic, clinical and laboratory variables, including vascular risk factors, data on HIV infection and duration of HAART. Variables with significant differences were included in a backward logistic regression model. Results: Twenty-seven cerebrovascular ischemic events occurred in 25 patients, with an incidence of 189 events (166 strokes) per 100,000 patients/year. Independent factors associated with cerebrovascular events were: history of high alcohol intake (OR 7.13, 95% CI 1.69–30.11; p = 0.007), a previous diagnosis of AIDS (OR 6.61, 95% CI 2.03–21.51; p = 0.002) and fewer months under HAART (OR 0.97, 95% CI 0.96–0.99; p < 0.001). Six patients (24%) had large artery atherosclerosis: they had a similar HAART duration to controls. Conclusions: Stroke incidence is high in patients with HIV-1 infection treated with HAART. Duration of HAART exerted a global protective effect for cerebrovascular ischemic events, and our results do not support a major role in large artery atherosclerosis stroke. High alcohol intake is a major risk factor for stroke in these patients.
Infarction Involving the Insula and Risk of Mortality after Stroke
Authors: Borsody Mark , Warner Gargano Julia , Reeves Mathew , Jacobs Bradley
Published: April 2009

Background: Cerebral infarction involving the insula has been associated with decreased survival following stroke. We hypothesized that infarct volume may reduce this association. Methods: The subjects were acute stroke patients who had consented to 2-year follow-up after stroke as part of the Michigan Acute Stroke Care Overview and Treatment Surveillance System registry. One hundred and eleven subjects exhibited areas of acute ischemic infarction on neuroimaging studies, 25 of whom had infarction involving the insula. Cox proportional hazard ratios (HR) were calculated to determine the association between mortality and acute infarction involving the insula, infarct volume, and other factors known to affect survival after stroke. Results: In unadjusted analysis, subjects with insula infarction had a nonsignificant twofold increase in 1-year mortality (HR = 2.1, 95% CI 0.6–7.0; p = 0.25). When adjusted for infarct volume, however, the HR for insula infarction was reduced to the null value (HR = 1.0, 95% CI 0.2–4.1; p = 1.00), indicating that the effect of insula infarction was entirely confounded by infarct volume. Conclusions: Insula infarction was associated with a nonsignificant twofold increase in mortality after stroke; however, this association was completely eliminated after adjusting for infarct volume. Infarct volume thus should be considered in future studies of insula infarction and mortality.
Responses to Diuretic Treatment in Gene-Targeted Mice Lacking Serum- and Glucocorticoid-Inducible Kinase 1
Authors: Artunc Ferruh , Ebrahim Ammar , Siraskar Balasaheb , Nasir Omaima , Rexhepaj Rexhep , Amann Kerstin , Friedrich Bjoern , Risler Teut , Lang Florian
Published: April 2009

Background/Aims: Serum- and glucocorticoid-inducible kinase 1 (SGK1) stimulates the epithelial sodium channel (ENaC), renal outer medullary K+ channel 1, Na+/K+-ATPase and presumably the Na+-Cl– cotransporter (NCC). SGK1-deficient mice (sgk–/–) show a compensated salt-losing phenotype with secondary hyperaldosteronism. The present experiments explored the role of SGK1 in the response to diuretics. Methods:sgk1–/– mice and their wild-type littermates (sgk1+/+) were treated with the ENaC blocker triamterene (200 mg/l), the Na+-K+-2Cl– cotransport inhibitor furosemide (125 mg/l), the NCC blocker hydrochlorothiazide (400 mg/l) and the mineralocorticoid receptor blocker canrenoate (800 mg/l) for 8 days. Renal SGK1 expression was studied using quantitative RT-PCR and immunofluorescence. Results: Diuretic treatment increased SGK1 mRNA and protein expression in the kidney of wild-type sgk1+/+ mice. The responses to furosemide, hydrochlorothiazide or canrenoate were not different between sgk1+/+ and sgk1–/– mice, and were accompanied by moderate increases in plasma aldosterone and urea concentrations. However, treatment with triamterene in sgk1–/– mice (but not in sgk1+/+ mice) led to severe, eventually lethal, body weight loss as well as increases in plasma aldosterone, urea and K+ concentrations. Conclusions: SGK1 is required for diuretic tolerance to triamterene. The observations confirm the impaired kaliuretic potency of sgk1–/– mice and point to a role of SGK1 in renal Na+ reabsorption by mechanisms other than ENaC.
A Subtest of the MMSE as a Valid Test of Episodic Memory? Comparison with the Free and Cued Reminding Test
Authors: Carcaillon Laure , Amieva Hélène , Auriacombe Sophie , Helmer Catherine , Dartigues Jean-François
Published: April 2009

Background/Aims: Episodic memory impairment is known to be the core of Alzheimer’s disease (AD) dementia syndrome and one of the earliest domains to decline. However, episodic memory tests are long and expensive. Methods: In a sample of the French Three-City Study (n = 1,516), we aimed at validating a subtest of the Mini-Mental State Examination (MMSE) specifically measuring episodic memory. We focused on the correlation between 7 MMSE subscores and 4 scores of the Free and Cued Selective Reminding Test (FCSRT) evaluating episodic memory. We performed linear regressions and principal component analyses to identify which MMSE subscores were better correlated with the FCSRT scores. Thereafter, we conducted validation analyses on the whole sample (n = 9,077). Results: We found that subscores for orientation to time and the 3-word recall task were well correlated with FCSRT scores. The summation of these 2 subscores was more strongly associated with dementia and AD than the FCSRT scores and the total MMSE score. Conclusion: Orientation to time and the 3-word recall task might provide a good measure of episodic memory. Making the evaluation of episodic memory faster and cheaper, this finding can be of direct interest for practitioners and epidemiologists.
Prevalence of Occult Hepatitis B Virus Infection in a General Adult Population in Korea
Authors: Song Eun Young , Yun Yeo Min , Park Myoung Hee , Seo Dong Hee
Published: April 2009

Objectives: We investigated the prevalence of hepatitis B virus (HBV) markers and occult HBV infection in a general adult population in Korea. Methods: HBsAg, anti-HBs and anti-HBc were analyzed on 1,091 samples of routine medical check-up examinees by chemiluminescence immunoassay. Nucleic acid amplification test (NAT) was performed on 1,047 HBsAg-negative samples by multiplex real-time polymerase chain reaction (PCR) kit for simultaneous detection of HBV, hepatitis C virus, and human immunodeficiency virus (Cobas Taqscreen MPX) in pools of six and reactive pools were resolved to individual samples, and further discriminated by PCR-based assay for HBV (Cobas Ampliscreen HBV). Results: The prevalences of HBsAg, anti-HBc, and anti-HBs were 4.0, 39.3, and 75.4%, respectively. The prevalence of anti-HBc significantly decreased with decreasing age (p< 0.001). Occult HBV infection was found in 7 (0.7%) of 1,047 HBsAg-negative subjects, and 5 of them were anti-HBc-negative. Sequencing of HBV S gene in 3 cases revealed one wild-type and two mutant strains (W74S, F85Y; T63I, W74S, T131N substitutions). Conclusions: This study helps to understand the current status of hepatitis B infection and the prevalence of occult HBV infection in a general adult population in Korea.
Molecular Analysis of Human Influenza Virus in Tehran, Iran
Authors: Soltani Z. , Hosseini M. , Shahidi M. , Hedayati M. , Kheiri M.T.
Published: April 2009

Background: To date there are no reports of molecular and phylogenetic analyses of human influenza virus in Tehran, Iran. Objectives: We isolated and characterized circulating influenza viruses in a sample of patients in Tehran. Methods: Nasal and pharyngeal swabs were collected from 57 individuals who were suspected of having influenza between October 2005 and January 2007. These samples were cultured and subsequently genotyped by RT-PCR and sequencing analyses. Results: Twelve of 57 samples (21%) were positive for human influenza virus. Out of the 12 positive samples, 7 were A/H3N2 (58%), 3 were A/H1N1 (25%) and 2 were B subtypes (17%). The phylogenetic analysis of the hemagglutinin gene showed that the H1N1 isolates were close to the A/New Caledonia/20/99 and the H3N2 isolates were close to the A/Panama/2007/99 and A/Moscow/10/99 vaccine strains. Conclusion: In a sample of clinical patients in Tehran, Iran, the predominant subtype of human influenza virus was determined to be A/H3N2, followed by A/H1N1 and B. In addition, phylogenetic analysis on H1 showed some genetic drifts from vaccine strains, but the phylogeny of H3 demonstrated that these isolates were from the previous vaccine strains.
Reasons for Dropout in Infertility Treatment
Authors: Van den Broeck U. , Holvoet L. , Enzlin P. , Bakelants E. , Demyttenaere K. , D’Hooghe T.
Published: April 2009

Background: The objective of this study was to explore the reasons why couples discontinue fertility treatment. Methods: A retrospective exploratory study was performed at the Leuven University Fertility Centre, a university hospital-based fertility center. Women who discontinued treatment between September 2000 and December 2001 were contacted in 2004–2005 by telephone for a standardized interview which covered 9 dropout reasons. For each reason, its importance on the decision to stop treatment was measured on an 11-point Likert scale. Results: On average, psychological burden (x = 5.96) had the highest impact on the decision to stop treatment followed by physical burden (x = 4.48) and female age (x = 3.64). Perceived lack of staff expertise (x = 1.84), negative impact on social contacts (x = 2.12) and financial burden (x = 2.16) had the lowest impact on the decision to stop treatment. Longer duration of infertility was significantly positively correlated with a higher rating of physical burden as a reason to discontinue treatment (r = 0.48; p < 0.05). Discussion: On average, psychological burden appears to be most frequently named as the number one reason to discontinue infertility treatment, whereas financial burden had the lowest impact. Longer duration of infertility is associated with more externalizing reasons to discontinue treatment.
Regulation of the Coagulation System by Vascular Endothelial Cells
Authors: Stern David M. , Kaiser Evan , Nawroth Peter P.
Published: April 2009

The endothelium plays an active role in the regulation of the coagulation mechanism. Multiple anticoagulant properties are operative on the cell surface in homeostasis. In the protein C/protein S pathway, for example, endothelium provides cofactors promoting activation of protein C, assembly of the activated protein C/protein S complex, and synthesizes protein S. In contrast, following exposure to cytokines and other pathologic stimuli, endothelial cell activation occurs. This activated state includes upregulation of procoagulant properties, such as tissue factor, with concomitant downregulation of anticoagulant cofactors, such as thrombomodulin. Modulation of endothelial cell coagulant properties by cytokines provides a mechanism linking activation of the clotting mechanism to the cellular response to environmental stimuli.
Biosynthesis of Human von Willebrand Factor
Authors: Verweij Cornells L.
Published: April 2009

Endothelium forms the inner lining of all blood vessels and, as a consequence, is in direct contact with the blood. Because of this and the synthesis and secretion of hemostatic components, the endothelium is able to modulate coagulation and fibrinolysis. An important hemostatic factor synthesized by endothelial cells is the von Willebrand factor (vWF). vWF is a large plasma glycoprotein which promotes the adhesion of platelets to the vessel wall after a vascular injury. vWF is initially synthesized as a pre-pro-polypeptide. During its transport to the outside of the cell, the single-chain polypeptides are assembled into multimers. The pro-polypeptide can be cleaved and also be secreted. Free pro-polypeptide is identified as von Willebrand antigen II, a plasma glycoprotein of unknown function. Plasma vWF consists of a heterogenous series of multimers, composed of an apparently single-type glycoprotein subunit, linked together by disulfide bonds. The hemostatic potency of vWF was shown to increase with increasing multimer size. Therefore, the multimeric assembly of vWF is a crucial aspect in vWF biosynthesis. Furthermore, vWF synthesized by endothelial cells can either be secreted constitutively or stored and released upon stimulation of the endothelial cell. In this review, data are presented which contribute to the understanding of the biosynthetic pathway and complex processing which vWF has to undergo before it is secreted by the endothelial cell. These data have allowed a prediction of the sequential events underlying vWF biosynthesis, processing, multimer assembly, and secretion.
Storage and Secretion of von Willebrand Factor by Endothelial Cells
Authors: Reinders Jan Hendrik , de Groot Philip G. , Sixma Jan J. , van Mourik Jan A.
Published: April 2009

Endothelial cells synthesize and store von Willebrand factor. We have studied the storage and secretion of von Willebrand factor in cultured human umbilical vein endothelial cells. In particular, we were interested in the nature of the storage compartment and the effects of perturbation on the storage and secretion processes. The storage compartment for von Willebrand factor was isolated from homogenates of endothelial cells. By an immunostaining technique the isolated vesicles stained for von Willebrand factor. The staining pattern was similar to that of Weibel-Palade bodies in intact endothelial cells. We concluded that the storage compartment containing von Willebrand factor is identical to the Weibel-Palade body. The von Willebrand factor of the isolated storage vesicles is predominantly constructed of polypeptide chains with a Mr of 220 kD. On the other hand, von Willebrand factor continuously secreted by endothelial cells is constructed of both a 220 kD and a larger precursor (apparent Mr of 275 kD) subunit. The storage vesicles contain von Willebrand factor that supports ristocetin-induced platelet aggregation. Thus, endothelial cells store fully processed, biologically active von Willeband factor within Weibel-Palade bodies. Short-term ( < 1 h) treatment of endothelial cells with the perturbing phorbol ester 4β-phorbol-12-myristate-13-acetate (PMA) results in release of cellular stored von Willebrand factor. 24–48 h after exposure to PMA the endothelial cell distribution of von Willeband factor is changed distinctly. While the contents of the von Willebrand factor storage sites in the cells are gradually restored within 48 h, enhanced amounts of von WiUebrand factor are secreted into the medium. The number as well as the size of von Willebrand factor storage granules in the endothelial cells increase after exposure to phorbol ester, as determined by immunofiuorescence microscopy. Phorbol ester treated cells release stored von Willebrand factor 48 h after they have been stimulated. PMA decreases the von Willebrand factor contents of the extracellular matrix; the deposition of von Willebrand factor in the subendothelium is blocked by PMA, whereas the degradation of matrix von Willebrand factor is not affected. Thus, perturbation of endothelial cells changes the cellular distribution of von Willebrand factor.
Regulation of the Synthesis and Secretion of Plasminogen Activators by Endothelial Cells
Authors: van Hinsbergh Victor W.M.
Published: April 2009

Plasminogen activators (PAs) play a role in fibrinolysis, tissue remodelling, tumor invasion, and reparative processes. Vascular endothelial cells produce tissue-type PA (t-PA), an important regulator of fibrinolysis, and PA inhibitor 1. They can also synthesize a second type of PA, urokinase-type PA (u-PA). The regulation of synthesis and secretion of these PAs by human and bovine endothelial cells in vitro is reviewed. The synthesis of t-PA and u-PA varies between endothelial cells, depending on their vascular origin. The production of PA activity by endothelial cells is regulated at various levels: (1) induction of newly synthesized t-PA or u-PA molecules; (2) rapid release of t-PA from endothelial cells; (3) conversion of single-chain u-PA in the more active two-chain u-PA; (4) interaction of PAs with cellular receptors and matrix components, and (5) interaction of PAs with specific inhibitors.
Fibrinolytic System of Vascular Endothelial Cells
Authors: Schleef Raymond R. , Loskutoff David J.
Published: April 2009

The regulation of the fibrinolytic system is of critical importance during hemostasis, wound repair, neoplasia, inflammation, and a variety of other biologic processes. This control is achieved in a large part through the action of specific plasminogen activator inhibitors (PAIs). Cultured endothelial cells (ECs) produce type 1 PAI (PAI-1), the physiologic inhibitor of tissue-type plasminogen activator. PAI-1 is one of the most highly regulated of the fibrinolytic components produced by ECs. Its synthesis is modulated by a variety of compounds including endotoxin, thrombin, transforming growth factor β, interleukin 1 and tumor necrosis factor α. Recent studies suggest that PAI-1 is synthesized by ECs as an active molecule, but that it spontaneously decays into a latent form in solution. Specific components present in the extracellular matrix of ECs and in plasma bind to PAI-1 and prevent this inactivation. The unexpected finding that cultured ECs also produce type 2 PAI (PAI-2) introduces a previously unsuspected level of complexity to our understanding of this system and raises the possibility that the altered fibrinolytic activity of ECs following various treatments, or of blood in certain individuals, may reflect changes in either one of these inhibitors.
Fatty Acid Metabolism and the Vascular Endothelial Cell
Authors: Buchanan Michael R. , Crozier Gayle L. , Haas Thomas A.
Published: April 2009

Fatty acid metabolism by vascular endothelial cells occurs both under basal conditions and following endothelial cell stimulation or injury. Under basal conditions, endothelial cells are metabolically very active and rapidly turn over triglycerides and synthesize 13-hydroxyoctadecadienoic acid from linoleic acid via the cytosolic enzyme, hω6-lipoxygenase. When endothelial cells are stimulated (or injured), these pathways are turned off, and, instead, arachidonic acid is liberated from the membrane phospholipids and metabolized into prostacyclin via the cyclooxygenase enzyme. The biological relevance of these two fatty acid metabolites is discussed in respect to the regulation of cell/cell interactions during both ‘homeostasis’ and ‘injury’.
Structure and Function of Endothelial Cell Integrins
Authors: Giltay Jacques C. , van Mourik Jan A.
Published: April 2009

Studies on the identification of molecules involved in the interaction of endothelial cells with their environment have led to the discovery of membrane receptors that are similar or identical to previously characterized platelet membrane glycoproteins. Some of these surface molecules belong to a family of widely distributed cell adhesion receptors, termed integrins. One of the integrins, the vitronectin receptor, a platelet glycoprotein (GP) IIb-IIIa related molecule, has now been characterized in some detail. It is a heterodimeric molecule consisting of a subunit similar, but not identical, to GP IIb and a subunit (almost) identical to GP IlIa. Alloantigens (Zwa, Zwb, and Yukb) expressed by platelet GP IlIa are also expressed by endothelial GP IlIa. The vitronectin receptor is involved in the adhesion of endothelial cells to Arg-Gly-Asp-containing immobilized proteins such as vitronectin, fibrin-ogen, and von Willebrand factor. Endothelial cells also express a molecule indistinguishable from the platelet VLA-2 or GP Ia-IIa complex which is another member of the integrin family. This molecule functions as a platelet collagen receptor, and perhaps it also functions as a collagen receptor on endothelial cells. By mediating cell-matrix contact, the vitronectin receptor, VLA-2 and other similar receptors might be involved in the anchorage of endothelial cells to their extracellular matrix.
Randomized Trial of a Low-Molecular-Weight Heparin (Kabi 2165) versus Adjusted-Dose Subcutaneous Standard Heparin in the Prophylaxis of Deep-Vein Thrombosis after Elective Hip Surgery
Authors: Dechavanne M. , Ville D. , Berruyer M. , Trepo F. , Dalery F. , Clermont N. , Lerat J.L. , Moyen B. , Fischer L.P. , Kher A. , Barbier P.
Published: April 2009

124 patients undergoing total hip replacement were randomly allocated to receive Kabi 2165, 2,500 anti-Xa units twice a day (group A); Kabi 2165, 2,500 anti-Xa units twice a day during the first 48 h postoperatively and then 5,000 anti-Xa units once a day (group B), or adjusted-dose standard heparin, monitored by activated partial thromboplastin time (group C). The first dose was given 2 h before surgery in the three groups. Deep-vein thrombosis (DVT) was detected by radiolabelled fibrinogen uptake and bilateral venography was performed in patients who had a positive scan. In patients who had a negative scan, bilateral venography was performed routinely the day before discharge from hospital. The frequency of DVT demonstrated by venography was 4.9% in group A, 7.3% in group B and 10% in group C. The difference between the three groups was not statistically significant. The incidence of proximal DVT was 2.4, 2.4 and 7.5%, respectively, for the three groups. There was no significant difference between the three groups with respect to mean estimated blood loss, the number of blood units transfused, wound hematoma formation, or hemoglobin and hematocrit levels.
Comparative Study on a New One-Stage Clotting Assay for Heparin and Its Low Molecular Weight Derivatives
Authors: Harenberg J. , Giese C. , Knödler A. , Zimmermann R.
Published: April 2009

The effects of a normal and a low molecular weight (LMW) heparin fraction were compared by four coagulation methods. Plasma samples of patients were investigated who were treated with normal heparin or with a LMW heparin. The study was undertaken to analyze the interrelationship between the coagulation methods: Heptest, activated partial thromboplastin time, thrombin clotting time, and S 2222 chromogenic anti-factor Xa test. The results showed a high correlation between Heptest and S 2222 anti-factor Xa method for unfractionated and LMW heparin (r = 0.91 and 0.90). Comparing the coagulation times in seconds of Heptest and aPTT, the correlations were r = 0.56 (normal heparin) and 0.15 (LMW heparin). The correlation between the coagulation times of Heptest and thrombin clotting time were r = 0.65 and 0.25, respectively. The correlations between the coagulation methods were higher, when coagulation times rather than transformed values to units per liter of the Heptest and of the S 2222 anti-factor Xa method were employed. Furthermore, the data demonstrate a high sensitivity of the Heptest to conventional and LMW heparin, whereas activated partial thromboplastin time and thrombin clotting time are less sensitive to either heparin. For laboratory control of LMW heparin, Heptest and S 2222 chromogenic method are reliable tests. Therapeutic ranges will have to be established.
Protein C in the Neonatal Period
Authors: Takamiya O. , Kinoshita S. , Niinomi K. , Yoshioka K.
Published: April 2009

Protein-C activity and antigen were measured in 141 full-term infants during the first month of life. The levels of both protein-C activity and antigen were about one third the level for normal adults in cord blood, and significantly lower than the cord blood during the 1st to 2nd days of life. They increased with age progressively, but did not reach the lowest limit in normal adults even in the first month. The low ratio of protein-C activity and antigen was demonstrated in some infants within the first 4 days of life. The precipitin arc of neonatal infants, which had a discrepancy between protein-C activity and antigen levels, showed an anodal shift upon agarose gel electrophoresis in the presence of Ca2+. The abnormal protein C in the neonatal period may be regarded as protein induced by vitamin-K absence or antagonist.
Distinctive Features of Procoagulant Response of Monocytes from Diabetic Patients
Authors: Jude Brigitte , Watel Annie , Fontaine Odile , Fontaine Pierre , Cosson Alain
Published: April 2009

The procoagulant activity (PCA) of disrupted monocytes was examined in 32 diabetic patients (26 with insulin-dependent and 6 with non-insulin-dependent diabetes) versus 30 control subjects. Diabetes monocytes exhibited a weak PCA before any incubation, associated in 10 cases with a significant amount of factor VII activity. Incubation led to a significant rise in PCA in diabetes cells, when stimulated with lipopolysaccharide or not, and in control cells only after stimulation. In incubated diabetes cells, PCA was prothrombinase-like when factor VII was associated with the freshly isolated cells, and tissue factor-like (as in the controls) when no factor VII was associated with the cells. The characteristics of PCA were not correlated with clinical features or with the type of diabetes. Our study suggests that diabetes monocytes exhibit a higher level of PCA than control ones, possibly corresponding to an in vivo stimulation, or at least a higher responsiveness to stimuli occurring in vitro.
Antithrombotic Effects of Three Thrombin Inhibitors in a Rat Model of Laser-Induced Thrombosis
Authors: Krupinski K. , Breddin H.K. , Markwardt F. , Haarmann W.
Published: April 2009

The antithrombotic effects of three thrombin inhibitors (hirudin, NAPAP and argidipine) were investigated in an experimental thrombosis model using laser lesions of rat mesenteric venules. Furthermore, their in vitro anticoagulant activity (partial thromboplastin time, thrombin time, Heptest, inhibition of factor Xa and factor Xa) in human platelet poor plasma (PPP) and their in vitro and ex vivo activities were studied in rat plasma. All three thrombin inhibitors showed significant and dose-dependent antithrombotic effects after intravenous injection, if venules were damaged, which lasted for more than 4 but less than 8 h. The anticoagulant effect observed in vitro did not differ much between human and rat PPP. The two synthetic thrombin inhibitors NAPAP and argidipine were about as effective as hirudin in vitro; however, the ex vivo effect after intravenous injection of hirudin in rats was more pronounced than that observed with the two synthetic thrombin inhibitors. The antithrombotic effect of all three thrombin inhibitors in the laser model lasted much longer than the anticoagulant activity. This fact needs further investigations in the future.
Thrombin Activity and Oral Anticoagulant Therapy: A Preliminary Study
Authors: Marongiu F. , Sorano G.G. , Mameli G. , Mamusa A.M. , Cambuli A.B. , Conti M. , Sanna M.P. , Farci P. , Balestrieri A.
Published: April 2009

The aim of this work was to investigate whether the thrombin activity is related to the degree of anticoagulation induced by oral anticoagulants. Moreover, we tried to detect an optimal anticoagulation range at which the lowest possible thrombin activity can be reached. We investigated 28 patients (19 women and 9 men, mean age 54 ± 9 years). Anticoagulation had been induced by acenocoumarol for at least 1 year before the beginning of this study. The degree of anticoagulation was monitored by the thrombotest coagulation method. The therapeutic range was 5–13%. The thrombin activity was measured by means of the fibrinopeptide A radioimmunological assay. In 15, 7, and 6 of the patients, thrombotest and fibrinopeptide A were carried out twice, once, and three times, respectively. Our results show first of all a significant positive relationship between thrombotest and fibrinopeptide A (p < 0.001). Once this result was obtained, we tried to improve our identification of the behaviour of the thrombin activity in relation to the degree of anticoagulation assessed by thrombotest. For this purpose we employed a third-degree polynomial regression analysis which showed a better fit of the data. Since the curve became steeper from about 10% thrombotest levels, we divided the FPA values on the basis of thrombotest ranges. FPA values for the 14- to 25% thrombotest range were significantly different from those in the thrombotest range of 4–10 %. Moreover, FPA levels in the 11 to 13 % thrombotest range were significantly different from those in the thrombotest range of 4–10%. Our results suggest that a significant decrease in thrombin activity may be achieved only with a deep anticoagulation.
The Contribution of Individual Lipoproteins to the Degradation of Platelet-Activating Factor in Human Serum
Authors: Ostermann G. , Kostner G.M. , Gries A. , Malle E. , Till U.
Published: April 2009

Platelet-activating factor (PAF) is rapidly degraded in vivo by the action of a specific acetylhydrolase. Measuring the PAF-acetylhydrolase activity in serum from 12 healthy volunteers a maximum velocity of 67.2 ± 11.8 nmol/min × ml and a Km value of 15.8 ± 2.9 μmol/l were ascertained. More than 90% of the activity was found to be associated with lipoproteins. It was detected in isolated VLDL, LDL, Lp(a) as well as HDL2 but not in HDL3. The PAF-acetylhydrolase activities associated with the various lipoproteins were shown to behave like a unique enzyme with distinct kinetic properties. Because VLDL and LDL were found to take up about 5 and 2.5 times more PAF with respect to their mass than HDL, it is concluded that lipoproteins affect the PAF-acetylhydrolase activity at the level of substrate presentation. As a consequence of the distinct kinetic properties, the lipoprotein-associated PAF-acetylhydrolase activities do not contribute proportionately to the degradation of PAF in serum. The latter is shown to depend primarily on the amount of PAF-acetylhydrolase bound to the apoprotein B-containing lipoproteins.
Comparison of the Effect of Aspirin and Choline Magnesium Trisalicylate on Thromboxane Biosynthesis in Human Platelets: Role of the Acetyl Moiety
Authors: Danesh B.J. , McLaren M. , Russell R.I. , Lowe G.D.O. , Forbes C.D.
Published: April 2009

Parameters of platelet thromboxane biosynthesis were measured 24 h after ingestion of equivalent salicylate doses (500 mg) of aspirin (ASA) and choline magnesium trisalicylate (CMT), a non-acetylated salicylate. In random order, 10 healthy volunteers received these drugs on 2 separate days, 2 weeks apart. While ASA significantly prolonged bleeding time, and decreased plasma thromboxane generation and serum thromboxane B2 levels, CMT failed to produce such effects. Thus CMT, which lacks an acetyl moiety in its structure, has no inhibitory effect on platelet thromboxane biosynthesis, and may therefore be considered safer than ASA for therapeutic use, when inhibition of platelet function can be hazardous.
Automated Amidolytic Method for Evaluating the Activated Partial Thromboplastin Time Compared with a Conventional Coagulation Method
Authors: Tripodi A. , Poggio M. , Scapellato L. , Mannucci P.M.
Published: April 2009

We report studies of the validity and clinical application of a new amidolytic method for evaluating the activated partial thromboplastin time (APTT) compared with a conventional clotting method. The results with the two methods were well correlated for normal plasma and plasma from hemophilia patients. Congenital deficiencies of the intrinsic coagulation pathway other than hypo- and dysfibrinogenemia detected by the amidolytic method agreed with those detected by the clotting APTT. The results with the two methods for plasma from patients under heparin treatment were statistically different, suggesting a lesser sensitivity of the amidolytic method to heparinization. The use of the amidolytic APTT reagent in combination with factor VIII and IX deficient plasma allowed the measurement of both factors. The results obtained with normal and hemophilic plasma were in agreement with those obtained with the one-stage clotting method in all except two occasions. Even though the amidolytic method demonstrated the presence of the lupus anticoagulant in the majority of tested samples of known lupus subjects, it was less sensitive to the abnormality than the clotting method.
Reduced Sensitivity of Human Platelets to PAF-Acether following Ticlopidine Intake
Authors: Chignard M. , Lalau Keraly C. , Delautier D. , Sebag C. , Bouloux C. , Motte G. , Benveniste J.
Published: April 2009

We investigated in 9 patients the effect of a 7-day treatment by Ticlopidine (250 mg b.i.d.) on washed platelets activation by PAF-acether in comparison with adenosine 5′-diphosphate (ADP) and arachidonic acid (AA). Aggregations induced by ADP were totally suppressed upon drug administration. AA-induced aggregations were partly but significantly inhibited (p < 0.05). Responses of platelets to PAF-acether before treatment differed from patient to patient. A paired Student’s test and a two-way analysis of variance showed a significant inhibitory effect of Ticlopidine treatment on PAF-acether-induced aggregation. The inhibitory effect of Ticlopidine or its metabolite(s) was evidenced after platelet washing procedure, suggesting a persistent effect of this drug on platelet after administration of the drug has been stopped.
Effect of Antibiotics on Laser-Induced Thrombus Formation in Rat Mesenteric Arterioles
Authors: Weichert W. , Breddin H.K.
Published: April 2009

Antibiotics were tested in a thrombosis model, in which thrombi are produced in small rat mesenteric arterioles. An interference contrast system based on a Leitz Orthoplan microscope, was used to visualize thrombus formation. Vascular lesions were produced with a Coherent CR-2 supergraphite ion laser (argon laser) in arterioles of 25–35 μm diameter.Cefmenoxim, cefotaxim (i.v.) and cephalexin orally at doses of 20 and 40 mg/kg and gentamycin 10 and 20 mg/kg (i.v.) had a marked and significant antithrombotic effect. Even more effective were cefoperazon and lamoxactam 20 and 40 mg/kg (i.v.) and tobramycin 10 and 20 mg/kg (i.v.). Azlocillin, cefoxitin, mezlocillin or spectinomycin (20 mg/kg i.v.) and penicillin or piperacillin (50 mg/kg i.v.) also showed a significant antithrombotic effect, which, however, disappeared on doubling of the applied dose.
A PAF-Acether Antagonist (N 48740 RP/Rhône-Poulenc) and Laser-Induced Thrombi in Rat Mesenteric Vessels
Authors: Weichert W. , Breddin H.K.
Published: April 2009

N 48740 RP, a pyrrolo(1,2-c)thiazole derivative and platelet-activating factor inhibitor, was tested in a thrombosis model, in which thrombi are produced in small rat mesenteric vessels. A phase contrast system, based on a Leitz Orthoplan microscope, was used to visualize thrombus formation. Vascular lesions were produced with a Coherent CR-2 supergraphite ion laser (argon laser) in vessels of 25–35 μm diameter. The results show a dose-dependent (5–20 mg/kg i.v.) antithrombotic effect of N 48740 RP which reaches its maximum between 30 min and 2 h after the injection and slowly decreases during the following 24–48 h.