bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acute hepatitis C in HIV‐infected men who have sex with men
Authors: Ghosn J , Pierre‐François S , Thibault V , Duvivier C , Tubiana R , Simon A , Valantin MA , Dominguez S , Caumes E , Katlama C 
Published: July 2004

BackgroundHepatitis C virus (HCV) is usually transmitted via the parenteral route, but there are widely discrepant findings on its possible sexual transmission. Thus there are no recommendations concerning protected sex for couples in which only one partner is HCV‐infected. Whether HIV or other sexually transmitted diseases could favour HCV transmission remains unclear, but recent data suggesting an increasing incidence of acute HCV in HIV‐infected men underline the major public health implications of this issue.Case reportsBetween June 2002 and July 2003, five HIV‐infected homosexually active men presented with primary (n=4) and secondary (n=1) syphilis and concomitant abnormal liver function tests revealing acute asymptomatic HCV seroconversion. Other causes of acute viral hepatitis were inquired into and excluded. Highly at‐risk sexual behaviour, including unprotected anal intercourse and unsafe oral sex, with concomitant syphilis, was found to be the only identifiable important risk factor for transmission of HCV.ConclusionsSexual transmission may be fuelling a significant increase in HCV seroconversions among HIV‐infected men who have highly risky sexual behaviours. Given the recent data suggesting the spread of sexually transmitted infections among HIV‐infected gay men, specific recommendations concerning safe sex are urgently needed.
Determination of indinavir and nelfinavir trough plasma concentration efficacy thresholds according to virological response in HIV‐infected patients
Authors: Duval X , Peytavin G , Albert I , Bénoliel S , Ecobichon J‐L , Brun‐Vézinet F , Mentré F , Leport C , Vildé J‐L 
Published: July 2004

BackgroundThere is evidence to suggest a pharmacokinetic–pharmacodynamic relationship in HIV‐infected patients receiving protease inhibitor (PI)‐containing highly active antiretroviral therapy (HAART); however, the effective trough PI plasma concentrations achieved have not been precisely determined.MethodsThe relationship between HIV viral load and concomitant PI trough plasma concentration (Ctrough) was evaluated in 101 patients receiving at least 4 months of thrice daily indinavir (IDV)‐containing (n=68) or nelfinavir (NFV)‐containing (n=33) HAART. The more discriminating Ctrough efficacy thresholds were determined statistically for each PI by using the raw Ctrough and the time‐corrected Ctrough, using the precise delay since the last PI intake and the half‐life of each PI.ResultsFor IDV (P=0.002) and NFV (P=0.019) median Ctrough levels were higher in patients with undetectable viral load [0.23 mg/L (n=30) and 2.3 mg/L (n=16) respectively] than in patients with detectable viral load [0.11 mg/L (n=38) and 0.6 mg/L (n=17) respectively]. Ctrough levels of IDV (r=−0.45; P<0.0001) and NFV (r=−0.43; P=0.011) were correlated with the concomitant viral load. The more discriminating Ctrough efficacy thresholds were estimated statistically as 0.12 mg/L for IDV and 0.5 mg/L for NFV. When Ctrough values were time‐corrected, the Ctrough efficacy thresholds, 8 h after the last intake, were 0.15 mg/L for IDV and 0.65 mg/L for NFV.ConclusionsThese results support the importance of achieving minimal effective Ctrough to improve the virological efficacy of PI‐containing HAART, and specify the target concentrations for IDV and NFV.
Transient groundwater impacts on the development of paleoclimatic lake records in semi‐arid environments
Authors: Urbano L. D. , Person M. , Kelts K. , Hanor J. S. 
Published: July 2004

AbstractLacustrine sedimentary deposits are a primary archive of terrestrial paleoclimatic information, and groundwater fluxes under arid climates can dominate water budgets in lake and playa environments. In this paper, we investigate the effects of basin‐scale water table fluctuations on lacustrine paleoclimatic records in arid regions using the hydrogeologic model MWT3D. Boundary conditions for paleo‐recharge over the past 57 ka, land surface topography, the location of lakes, and subsurface geology were based on information available for a 600‐km cross section across the western Murray Basin, Australia. Results indicate the importance of the physical interaction between the water table and the land surface in controlling the location and the timing of formation of paleoclimatic lacustrine records. Lakes in different positions across the watershed preserved different records of climate (wet versus dry), although the same recharge history was applied. Changes in groundwater seepage to the surface lagged behind the climatic signal between 500 and 220 years across the basin. The size of the flow system, specifically the distance from the local discharge point to the adjacent groundwater divide, was the primary control on the time lag. With large fluctuations in water table elevation (>50 m) this distance changes considerably from wet to dry climatic conditions. Our results are largely consistent with observed paleoclimatic records derived from lakes across the Murray Basin.
Temporal change in groundwater level following the 1999 (Mw = 7.5) Chi‐Chi earthquake, Taiwan
Authors: Wang C.‐Y. , Wang C.‐H. , Kuo C.‐H. 
Published: July 2004

AbstractWe examine the post‐seismic change in the groundwater level following the 1999 (Mw = 7.5) Chi‐Chi earthquake in central Taiwan, as recorded by a network of 70 evenly distributed hydrological stations over a large alluvial fan near the epicenter. Four types of post‐seismic responses may be distinguished. In type 1, the groundwater level declined exponentially with time following a coseismic rise. This was the most common response in the study area and occurred in unconsolidated sediments on the Choshui River fan. In type 2, the groundwater level rose exponentially with time following a coseismic fall. This occurred in the deformed and fractured sedimentary rocks in the foothills near the Chelungpu fault that ruptured in the Chi‐Chi earthquake. In type 3, the groundwater level continued to decline with time following a coseismic fall. This also occurred in the deformed and fractured sedimentary rocks near the ruptured fault. Finally, in type 4, the groundwater level, following a coseismic rise, stayed at the same level or even rose with time before it eventually declined. This occurred mostly in unconsolidated sediments along the coast of central Taiwan and along the Peikang Stream. We analyze these post‐seismic responses by using a one‐dimensional model. Together with the results from well test, the analysis show that the type 1 response may be explained by an aquifer model with coseismic recharge and post‐seismic subhorizontal discharge across a length of 500–5000 m; the type 2 response may be explained by a model of coseismic discharge and post‐seismic recharge from surface water; the type 3 response may be explained by a model of coseismic discharge and post‐seismic subhorizontal discharge across a length of 500–5000 m; and the type 4 response may be explained by a model of coseismic recharge and sustained post‐seismic recharge from surface water. The characteristic time for the post‐seismic changes is similar to that for the groundwater‐level decline during dry seasons before the earthquake, suggesting that there was no earthquake‐induced changes in the aquifer properties (i.e. hydraulic conductivity), confirming the earlier results from recession analyses of the post‐seismic streamflow elsewhere after several earthquakes.
The link between fluids and rank variation in the South Wales Coalfield: evidence from fluid inclusions and stable isotopes
Authors: Alderton D. H. M. , Oxtoby N. , Brice H. , Grassineau N. , Bevins R. E. 
Published: July 2004

AbstractFluid inclusion and stable isotope data from quartz and carbonate minerals in fracture fillings and ‘ironstone’ nodules from the South Wales Coalfield have been used to characterise the fluids generated during basin evolution and associated coalification. Carbonates grew first, probably at relatively shallow depths and low temperatures (<100°C). The carbonates exhibit a trend of increasing C‐isotopic values across the coalfield, ranging from δ13C = −12‰ VPDB in the SE of the coalfield to 0‰ VPDB in the NW, possibly as a result of increasing methanogenesis in the deeper (NW) parts of the coalfield. Quartz formed at a later stage of basin formation, probably at temperatures between 150 and 200°C. Fluid inclusions in these minerals suggest that burial and coalification of the sediments were associated with mixed aqueous–petroleum fluids. Furthermore, the density of these petroleum fluids decreases towards the NW of the coalfield, where the rank of the associated coal increases to anthracite grade. The study confirms that the composition and temperature of these fluids closely correlate with the variations in coal rank, indicating a possible causal link. The data also give general support to models that propose regional fluid flow in the basin. and are consistent with the erosion of approximately 2 km of section which is not preserved today. A geothermal gradient (at maximum burial) of 45°C km−1 is proposed, and thus no exceptionally anomalous thermal regime is required to explain coal rank variation.
Factors controlling free thermal convection in faults in sedimentary basins: implications for the formation of zinc–lead mineral deposits
Authors: Yang J. , Large R. R. , Bull S. W. 
Published: July 2004

AbstractStratiform sediment‐hosted Zn–Pb–Ag mineral deposits constitute about 40% of the Earth's zinc resources (Allen 2001), and in most cases their genesis involves the discharge of basinal brines near or on the seafloor through syndepositional faults (Sangster 2002). From the point of view of base metal exploration, it is therefore essential to identify all possible faults that formerly carried the upwelling ore‐forming solutions during mineralising events. This paper presents a numerical investigation of the relative importance of various physical parameters in controlling fluid discharge, recharge and heat transport in faults. A two‐dimensional, free convection of pure water, hydrogeological model is developed for the McArthur basin in northern Australia based on the surface geology, known stratigraphic and structural relationships and regional geophysical interpretations. Numerical experiments and sensitivity analyses reveal that faults with strong initial heat input, due to depth of penetration or magmatic activity, are the most likely candidates to carry discharge fluids to the sites of metal precipitation. Deeper, wider and more permeable faults are more likely to behave as the fluid discharge pathways, whereas shallow, narrow or less permeable faults act as marine water recharge pathways. Compared with these fault‐related factors, aquifer physical properties are less important in determining fluid flow patterns and the geothermal regime. These results are an important step in understanding hydrothermal fluid flow in sedimentary basins in order to develop effective exploration criteria for the location of stratiform Zn–Pb–Ag deposits.
Mathematical modeling of phase separation of seawater near an igneous dike
Authors: Lewis K. C. , Lowell R. P. 
Published: July 2004

AbstractWe provide a simplified treatment of phase separation of seawater near an igneous dike to obtain rough estimates of the thickness and duration of the two‐phase zone, the volume fractions of vapor and brine formed, and their distribution in the subsurface. Under the assumption that heat transfer occurs mainly by thermal conduction we show that, for a 2‐m wide dike, the maximum width of the two phase zone is approximately 20 cm and that a zone of halite is initially deposited near the dike wall. The two‐phase zone is mainly filled with vapor. For a value of thermal diffusivity of a = 10−6 m2 sec−1, the two‐phase zone begins to disappear at the base of the system after 13 days, and disappears completely by 16 days. For a lower value of thermal diffusivity, the width of the two‐phase region does not change appreciably but its duration increases as a−1. The width of the two‐phase zone determined by this simplified model agrees reasonably well with transient numerical solutions for the analogous two‐phase flow in a pure water system; however the duration of two‐phase flow is matched better using a smaller value of a. We compare the seafloor values of vapor salinity and temperature given by the model with vapor salinity data from the ‘A’ vent at 9–10°N on the East Pacific Rise (EPR) and argue that either non‐equilibrium thermodynamic behavior or near‐surface mixing of brine with vapor in the two‐phase region may explain the discrepancies between model predictions and data.
ST‐Depression with Negative T Waves in Leads V4–V5—A Marker of Severe Coronary Artery Disease in Non‐ST Elevation Acute Coronary Syndrome: A Prospective Study of Angina at Rest, with Troponin, Clinical, Electrocardiographic, and Angiographic Correlation
Authors: Nikus Kjell C. , Eskola Markku J. , Virtanen Vesa K. , Vikman Saila , Niemelä Kari O. , Huhtala Heini , Sclarovsky Samuel 
Published: July 2004

Background: The significance of ST‐segment depression in acute coronary syndrome has been the subject of debate for many decades. Studies indicate that different manifestations of ST/T changes may have significantly different prognostic implications. Methods and Results: We studied the correlation of ST/T changes in 12‐lead electrocardiography recorded during pain, to clinical and angiographic findings and in‐hospital prognosis, in patients with non‐ST‐elevation acute coronary syndrome and elevated troponin levels. Fifty consecutive patients could be differentiated into two groups: (1) 25 patients with ST‐segment depression and a negative T wave maximally in leads V4–5, (2) 25 patients with ST‐segment depression and a positive T wave in the precordial lead with maximal ST‐segment depression. Patients in group I had significantly more often left main or left main equivalent coronary artery disease; 76% versus 8% (P < 0.001), heart failure; 40% versus 4% (P = 0.005), and higher in‐hospital mortality; 24% versus 0% (P = 0.02), than patients in group II. The troponin levels did not differ significantly between the groups. Conclusions: In patients with non‐ST‐elevation acute coronary syndrome and elevated troponin levels two subgroups could be identified. Transient ST‐segment depression and a negative T wave maximally in leads V4–5 during anginal pain predicts left main, left main equivalent, or severe three‐vessel coronary artery disease with high sensitivity and specificity. In patients with ST‐segment depression and a positive T wave, there is a high probability of one‐vessel disease.
Is Baseline Autonomic Tone Associated with New Onset Atrial Fibrillation?: Insights from the Framingham Heart Study
Authors: Singh Jagmeet P. , Larson Martin G. , Levy Daniel , Evans Jane C. , Tsuji Hisako , Benjamin Emelia J. 
Published: July 2004

Background: Recent reports have indicated that autonomic tone fluctuations measured by heart rate variability (HRV) precede episodes of paroxysmal atrial fibrillation (AF). Little is known about the impact of baseline autonomic tone and the development of new onset AF in a population‐based cohort. The purpose of this study was to assess the role of HRV as a predictor of new onset AF. Method: Ambulatory ECG recordings obtained from the Framingham Heart Study subjects attending a routine examination were processed for HRV. The HRV variables analyzed included standard deviation of normal R‐R intervals (SDNN), low frequency power (LF), high frequency power (HF), and LF/HF ratio. There were 1434 women and 1142 men (54 ± 14.1 years) eligible for the study. Results: In 12 years of follow‐up, 65 women and 67 men had new onset AF. The study had 80% power to detect a hazard ratio (HR) of 1.3 per standard deviation (SD) decrement in HRV. A one SD decrement in log LF/HF was associated with increased risk of developing AF (HR = 1.23; 95% confidence intervals (CI) = 1.06–1.44) in age‐ and sex‐adjusted models; the association was no longer significant (HR = 1.15; 95% CI = 0.98–1.35) after adjusting for potential confounders. Conclusion: Autonomic dysregulation at baseline, as reflected by an altered HRV is associated with risk of AF; however, this association does not persist after adjusting for potential confounders. Much of the apparent association between HRV and AF is mediated by traditional risk factors.
Detection of Multivessel Disease Post Myocardial Infarction Using an Exercise‐Induced QRS Score
Authors: Michaelides Andreas P. , Papapetrou Dimitris , Aigyptiadou Maria‐Niki K. , Psomadaki Zoi D. , Andrikopoulos George K. , Kartalis Athanasios , Fourlas Christos , Stefanadis Christodoulos I. 
Published: July 2004

Objective: The aim of this study was to investigate the ability of Athens QRS score values to detect stenoses in other coronary arteries than the obstructed ones (which caused the myocardial infarction [MI]) in patients with a history of MI. Methods: We studied 125 patients (93 males and 32 females, mean age 54 ± 7 years [range 45–68 years]) with a history of MI (46 patients with anterior MI, 54 patients with inferior MI, 25 patients with lateral MI). All patients underwent treadmill exercise testing and coronary arteriography. Results: Athens QRS score values were inversely related to the extent of CAD: −0.5 ± 0.3 mm for patients with 1‐VD (obstructed vessel), −3.4 ± 2.2 mm for patients with 2‐VD (obstructed vessel and stenosis in another vessel), and −5 ± 1.8 mm for patients with 3‐VD (obstructed vessel and stenoses in two more vessels). The ROC curves for the detection of multivessel disease showed that the area under the curve for QRS score values < −3 mm is significantly higher than the curve for ST‐segment depression ≥1 mm (0.948 vs 0.792, P < 0.001). Conclusions: Values of the Athens QRS score less than −3 may distinguish single‐ from multivessel coronary artery disease in patients with a history of MI.
Decrease/Disappearance of Pacemaker Stimulus “Spikes” Due to Anasarca: Further Proof that the Mechanism of Attenuation of ECG Voltage with Anasarca Is Extracardiac in Origin
Authors: Madias John E. 
Published: July 2004

Background: Recent work showed that AN leads to a decrement of the potentials of QRS complexes. Although the mechanism has been thought to be extracardiac in origin, and due to a decrease of the electrical impedance of the volume conductor from water overload, more proof on this will be welcome. It is hypothesized that the pacemaker “spikes” (PS) are independent of heart depolarization, and thus their change at the body surface with AN would be reflective of extracardiac influences. This study was designed to explore the impact of anasarca (AN) on the amplitude of PSs, and to further delineate the mechanism of ECG attenuation with AN. Methods: The sum of PS measurements in millimeters in the 6 limb leads (ΣPS6), and 12 ECG leads (ΣPS12), and the sum of QRS complexes in the 6 limb leads (ΣQRS6), and 12 ECG leads (ΣQRS12) were computed in six patients fitted with a pacemaker (3 with AN and 3 “controls”), and these variables were correlated with weight change. Results: Correlation of percentage change in weight and ΣPS12 was excellent (r =−0.88, P = 0.02), but not for ΣPS6 (r =−0.73, P = 0.1). Also, the percentage weight correlated well with ΣQRS6 (r =−0.82, P = 0.046), but not ΣQRS12 (r =−0.61, P = 0.2). Correlation of percentage change in ΣQRS6 and ΣPS6 was excellent (r = 0.91, P = 0.01), but not the percentage change in ΣQRS12 and ΣPS12 (r = 0.72, P = 0.11). Conclusions: PSs undergo amplitude attenuation in patients developing AN, similar to the one noted in the QRS complexes. Since these changes are independent of the cardiac activation, and are similar in extent to those impacting the QRS complexes, the attenuation of the voltage of the entire ECG curve in AN appears to be extracardiac in origin.
Patterns of QT Dispersion in Athletic and Hypertensive Left Ventricular Hypertrophy
Authors: Lonati Laura Maria , Magnaghi Gaia , Bizzi Caterina , Leonetti Gastone 
Published: July 2004

Objective: The objective of this article is to assess whether left ventricular hypertrophy (LVH) due to physical training or of hypertensive patients shows similarities in QT length and QT dispersion. Methods: A total of 51 subjects were studied: 17 essential hypertensive patients (27.7 ± 5.6 years), 17 athletes involved in agonistic activity (canoeing) (24.8 ± 6.1 years), and 17 normotensive healthy subjects as control group (24.8 ± 3.6 years). The testing protocol consisted of (1) clinic BP measurement, (2) echocardiography, (3) 12‐lead electrocardiographic examination (QT max, QTc max, QT min, QTc min, ΔQT, ΔQTc). Results: There were no significant differences between the body surface area, height, and age of the three groups. Clinic blood pressure was higher in hypertensives (146.5 ± 45.2/93.5 ± 4.9 mmHg) versus athletes (120.9 ± 10.8/77.1 ± 6.0 mmHg) and controls (123.5 ± 4.8/78.8 ± 2.9 mmHg) by definition. Indexed left ventricular mass (LVM/BSA) was significantly greater in both athletes (148.9 ± 21.1 g/m2) and hypertensives (117.1 ± 15.2 g/m2) versus controls (81.1 ± 14.5 g/m2; P < 0.01), there being no statistical difference among them. LVH (LVMI > 125 g/m2) was observed in all athletes, while the prevalence in hypertensives was 50%. In spite of this large difference in cardiac structure there were no significant differences in QT parameters between athletes and the control group, while hypertensive patients showed a significant increase in QT dispersion versus the two other groups (ΔQT 82 ± 2.1, 48 ± 1.3, 49 ± 2.3 ms; P < 0.01; ΔQTc 88 ± 2.0, 47 ± 1.4, 54 ± 2.7; P < 0.01). Conclusions: LVH induced by physical training activity is not associated with an increase in QT dispersion, whereas pathological increase in LVM secondary to hypertension is accompanied by an increased QT dispersion.
Abnormalities of the Repolarization Characteristics of Patients with Heart Failure Progress with Symptom Severity
Authors: Lang Christopher C. E. , Neilson James M. M. , Flapan Andrew D. 
Published: July 2004

Background: Congestive heart failure is a common condition with high mortality. Many of these deaths are sudden and unexpected. Ventricular action potential, surface repolarization (QT interval), and dispersion of repolarization are prolonged in the failing heart, contributing to arrhythmogenesis and sudden death. We studied the relationship between QT and heart rate (RR interval) from ambulatory recordings using a novel method in patients with ischemic heart disease and varying degrees of left‐ventricular impairment (IHD) and compared them to healthy subjects (HS). We compare the degree of abnormality with the functional impairment and ejection fraction. Methods: Using a previously described automated method for continuous estimation of the QT/RR characteristic that incorporates a correction formula for compensation of QT adaptation lag (VERDA, Del Mar Reynolds Medical Ltd., Hertford, UK), we compared recordings from 41 IHD patients with age‐matched HS. Results: IHD Patients have prolonged 24‐hour mean QTo (461 ms vs 426 ms, P < 0.01), and abnormal rate dependence relative to controls (24‐hour mean slope: 0.20 vs 0.14, P < 0.001; J: 0.38 vs 0.28, P < 0.001). There is increased temporal variation in J with respect to HS. These abnormalities of repolarization increase with worsening NYHA class, but do not correlate with ejection fraction. Conclusions: The use of a universal correction formula to compare dynamic QT data in IHD patients is inappropriate. The observed progressive abnormalities may be responsible for the high incidence of sudden death through promotion of arrhythmias.