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J Fort

Publications and source records attributed to J Fort.

At least 19 recordsLinked to original sources
PubMed2006

Fronts with continuous waiting-time distributions: theory and application to virus infections.

We generalize to arbitrary waiting-time distributions some results which were previously derived for discrete distributions. We show that for any two waiting-time distributions with the same mean delay time, that with higher dispersion will lead to a faster front. Experimental data on the speed of virus infections in a plaque are correctly explained by the theoretical predictions using a Gaussian delay-time distribution, which is more realistic for this system than the Dirac delta distribution considered previously [J. Fort and V. Méndez, Phys. Rev. Lett. 89, 178101 (2002)].

Animals↗
PubMed2006

[Compliance with the 2002 consensus document of the Spanish Society of Nephrology for the control of diabetic nephropathy in Catalonia (ECCODIAB)].

OBJECTIVE: To evaluate the level of compliance with the 2002 consensus document (Spanish Society of Nephrology) on guidelines for the detection, prevention and treatment of diabetic nephropathy in Catalonia. SUBJECTS AND METHODS: Multicenter (23 hospitals), observational, cross-sectional, descriptive study conducted in 413 diabetic patients (61.7% men, 38.3% women) with a median age of 66.2 +/-11.5 years (26-93 years). The ANOVA test (post-hoc analysis; p value< 0.05) was used to study the relationships between the stages of diabetic nephropathyand different variables. RESULTS: 90.3% of the patients had type 2 DM. The following anthropometric parameters were observed: BMI 29.8 +/- 5 kg/m2 (BMI > 30 kg/m2: 48.7%) and waist circumference 104.1 +/- 14 cm (48.6% men > 102 cm and 78.9% women > 88 cm). Serum creatinine 1.9 +/- 1.3 mg/dl and simplified MDRD equation 45.3 +/- 25.0 ml/min/1.73 m2 [65.8%with CKD stages 3 and 4]. 80% of patients had ophthalmologic examination and 52.8% antiplatelet treatment. Hb A1c was 7.3 +/- 1.3%, but the percentage of patients with glycated hemoglobin > 7% and 8% was 54.9 and 28.6% [only 50.2% had been seen by an endocrinologist in the last 6 months]. 52.8% of patients were treated with insulin and 44.1% with anti-diabetic drugs, although only 19.6% used the new anti-diabetic drugs. 61% of patients had an LDLc > 100 mg/dl (61% treated) and 44% had triglycerides (TG) > 150 mg/dl (72% treated). 95% of patients presented with hypertension (BP > or = 130/80 mmHg),91% were undergoing antihypertensive treatment (79.7% with angiotensin-converting enzyme inhibitors and / or angiotensin receptor blockers). 81% with microalbuminuria and 78%with established proteinuria were receiving anti-proteinuric treatment. Of the patients considered to be refractory to BP (>3 drugs), only 28.9% underwent ambulatory BP monitoring. Significant differences were observed between stages of diabetic nephropathy and glycated hemoglobin (HBA1c; p = 0.048), systolic blood pressure (SBP; p = 0.024), lipidic control (HDLc; p = 0.015 and TG; p = 0.034), anemia (Hb; p = 0.010) and CKD (creatinine and sMDRD; p = 0.000). The levels of compliance with the therapeutic objectives regarding lipid control (LDL < or = 100 mg/dl and TG< or = 150 mg/dl), BP < or = 130/80 mmHg and HbA1c < or =7% were 1 objective: 68%, 2 objectives: 21.8% and 3 objectives: only 4% of patients. CONCLUSIONS: According to the results of our study, only a reduced proportion of patients fulfilled the different therapeutic end-points indicated. Future measures will be directed at improving physician-patient relationships with the main aim of intensifying the therapeutic measures to attain better metabolic and blood pressure control, nephroprotection and prevention in the appearance of cardiovascular events.

Adult↗
PubMed2001

Speed of reaction-transport processes.

We present an approach to determining the speed of wave-front solutions to reaction-transport processes. This method is more accurate than previous ones. This is explicitly shown for several cases of practical interest: (i) the anomalous diffusion reaction, (ii) reaction diffusion in an advective field, and (iii) time-delayed reaction diffusion. There is good agreement with the results of numerical simulations.

Journal Article↗
PubMed2001

Equilibrium of drops on inclined hydrophilic surfaces.

Why does not gravity make drops slip down the inclined surfaces, e.g., plant leaves? The current explanation is based on the existence of surface inhomogeneities, which cause a sustaining force that pins the contact line. Following this theory, the drop remains in equilibrium until a critical value of the sustaining force is reached. We propose an alternative analysis, from the point of view of energy balance, for the particular case in which the drop leaves a liquid film behind. The critical angle of the inclined surface at which the drop slips down is predicted. This result does not depend explicitly on surface inhomogeneities, but only on the drop size and surface tensions. There is good agreement with experiments for contact angles below 90 degrees where the formation of the film is expected, whereas for greater contact angles great discrepancies arise.

Journal Article↗
PubMed2001

A randomized, double-blind, crossover clinical trial of diclofenac plus misoprostol versus acetaminophen in patients with osteoarthritis of the hip or knee.

OBJECTIVE: To perform a randomized, double-blind, crossover clinical trial of diclofenac + misoprostol versus acetaminophen in ambulatory patients with osteoarthritis of the hip or knee. METHODS: Patients in 12 ambulatory care settings were eligible if they were age >40 years and if they had Kellgren/Lawrence radiographic grade 2-4 osteoarthritis of the knee or hip and a score of > or =30 mm on a 100-mm visual analog pain scale. Patients were randomized to one of two groups, 75 mg diclofenac + 200 microg misoprostol twice daily or 1,000 mg acetaminophen 4 times daily (each for 6 weeks), and were then crossed over to the other treatment for 6 weeks. A placebo was included in each treatment regimen to enable double blinding. The primary outcome measures were the Western Ontario and McMaster Universities Osteoarthritis Index and the visual analog pain scale of the Multidimensional Health Assessment Questionnaire. Safety was assessed using a standard form to review adverse events. RESULTS: We enrolled 227 patients, of whom 218 provided data for the first treatment period and 181 provided data for both treatment periods. Significantly higher levels of improvement in the primary outcomes were seen for diclofenac + misoprostol than for acetaminophen (P < 0.001). Adverse events were more common when patients took diclofenac + misoprostol (P = 0.046). Diclofenac + misoprostol was rated as "better" or "much better" by 57% of the 174 patients who provided such ratings for both treatment periods, while acetaminophen was rated as "better" or "much better" by 20% of these patients, and 22% reported no difference (P < 0.001). Differences favoring diclofenac + misoprostol over acetaminophen were greater in patients with more severe osteoarthritis according to baseline pain scores, radiographs, or number of involved joints. CONCLUSION: Patients with osteoarthritis of the hip or knee had significantly greater improvements in pain scores over 6 weeks with diclofenac + misoprostol than with acetaminophen, although patients with mild osteoarthritis had similar improvements with both drugs. Acetaminophen was associated with fewer adverse events.

Acetaminophen↗
PubMed2000

Spleno-renal shunt blood flow is an accurate index of collateral circulation in different models of portal hypertension and after pharmacological changes in rats.

BACKGROUND/AIMS: Recently, we developed a new method to measure collateral blood flow in rats: splenorenal shunt (SRS) blood flow (BF). The aims were to evaluate the reproducibility of SRSBF measurement in different models of portal hypertension, and to investigate the ability of SRSBF to disclose pharmacological changes. METHODS: Hemodynamics were determined in anesthetized rats with secondary biliary, CCl4 or DMNA cirrhosis and portal vein ligation (PVL) under baseline and pharmacological (octreotide, vapreotide) conditions. The main measurements performed were: SRSBF by the transit time ultrasound (TTU) method and % portosystemic shunts (PSS) by the microsphere method. RESULTS: SRSBF was 6 to 10 times higher in portal hypertensive rats and was similar in the different models of cirrhosis but was higher in portal vein ligated rats than in cirrhotic rats (1.1+/-0.7 vs 0.6+/-0.7 ml x min(-1) x 100 g(-1), p=0.01). SRSBF was correlated with mesenteric %PSS (r=0.61, p<0.01), splenic %PSS (r=0.54, p<0.05), portal pressure (r= 0.32, p<0.05) and the area of liver fibrosis (r=0.33, p<0.05). Octreotide significantly decreased SRSBF (-23+/-20%, p<0.01 vs placebo: -6+/-8%, NS). Vapreotide significantly decreased SRSBF but not mesenteric or splenic %PSS compared to placebo. The variations in SRSBF (-26+/-32%) and in splenic %PSS (0+/-15%) with vapreotide were significantly different (p<0.05) and not correlated (r=-0.1, NS). CONCLUSIONS: Determination of SRSBF by TTU is an accurate way to measure collateral blood flow in different models of intra- and extra-hepatic portal hypertension in rats. Its sensitivity provides accurate measurement of pharmacological changes, unlike the traditional estimation of %PSS by the microsphere method.

Animals↗
PubMed1999

Long-term administration of PGE1 increases liver fibrosis and collateral blood flow in bile-duct-ligated rats.

BACKGROUND/AIMS: The aim of this study was to assess the effect of early and chronic administration of a prostaglandin E1 analogue (misoprostol) in the prevention of liver fibrosis and portal hypertension. METHODS: Liver fibrosis was induced by bile duct ligation. Controls had a sham operation. Bile-duct-ligated rats were divided into two groups: placebo (vehicle only) and misoprostol (10 microg/d by gavage) for 4 weeks after surgery. Liver fibrosis was assessed by the area of fibrosis (image analysis), liver hydroxyproline content and serum hyaluronate. Systemic and splanchnic hemodynamics were evaluated including spleno-renal shunt blood flow by the transit-time ultrasound technique. RESULTS: Mean arterial pressure was significantly lower in the misoprostol group (p<0.01). There was an unexpected increase in fibrosis parameters in the misoprostol group compared to the placebo group, e.g. area of fibrosis: 9.5+/-4.0 vs 15.0+/-8.1% (p<0.05). Spleno-renal shunt blood flow was significantly higher in the misoprostol group than in the placebo group (4.6+/-3.7 vs 2.2+/-2.0 ml/min, p<0.05) while portal pressure was unchanged. CONCLUSIONS: The early and chronic administration of misoprostol enhances porto-collateral circulation blood flow and the development of liver fibrosis in bile-duct-ligated rats.

Animals↗
PubMed1999

Speed of wave-front solutions to hyperbolic reaction-diffusion equations.

The asymptotic speed problem of front solutions to hyperbolic reaction-diffusion (HRD) equations is studied in detail. We perform linear and variational analyses to obtain bounds for the speed. In contrast to what has been done in previous work, here we derive upper bounds in addition to lower ones in such a way that we can obtain improved bounds. For some functions it is possible to determine the speed without any uncertainty. This is also achieved for some systems of HRD (i.e., time-delayed Lotka-Volterra) equations that take into account the interaction among different species. An analytical analysis is performed for several systems of biological interest, and we find good agreement with the results of numerical simulations as well as with available observations for a system discussed recently.

Journal Article↗
PubMed1999

Reaction-diffusion waves of advance in the transition to agricultural economics.

In a previous paper [J. Fort and V. Méndez, Phys. Rev. Lett. 82, 867 (1999)], the possible importance of higher-order terms in a human population wave of advance has been studied. However, only a few such terms were considered. Here we develop a theory including all higher-order terms. Results are in good agreement with the experimental evidence involving the expansion of agriculture in Europe.

Journal Article↗
PubMed1999

Irreversible thermodynamics of Poisson processes with reaction.

A kinetic model is derived to study the successive movements of particles, described by a Poisson process, as well as their generation. The irreversible thermodynamics of this system is also studied from the kinetic model. This makes it possible to evaluate the differences between thermodynamical quantities computed exactly and up to second-order. Such differences determine the range of validity of the second-order approximation to extended irreversible thermodynamics.

Journal Article↗
PubMed1999

Celecoxib, a COX-2--specific inhibitor: the clinical data.

Celecoxib offers the unique therapeutic prospect of alleviating pain and inflammation without the untoward gastrointestinal, renal, and platelet effects associated with conventional nonsteroidal anti-inflammatory drugs. This is possible because celecoxib is a cyclooxygenase-2 (COX-2)-specific inhibiting agent that inhibits the conversion of arachidonic acid to the prostaglandins that mediate pain and inflammation while having no effect on the formation of the prostaglandins that mediate normal homeostasis in the gastrointestinal tract, kidneys, and platelets and that are formed under the control of cyclooxygenase-1 (COX-1). Double-blind clinical trials have demonstrated that celecoxib is as effective in ameliorating the signs and symptoms of osteoarthritis and rheumatoid arthritis as naproxen and as effective as aspirin in reducing pain following dental extraction. Controlled trials have also shown that the incidence of gastroduodenal ulcers and the combined incidence of gastroduodenal ulcers and erosions are significantly lower with celecoxib therapy than with naproxen therapy and are similar to those associated with placebo administration. In a study of platelet function, it was found that a single 650-mg dose of aspirin profoundly diminished platelet function, while therapeutic doses of celecoxib exhibited no such effect. Celecoxib has been shown to be well tolerated, with incidences of adverse events similar to placebo in most instances. In summary, evidence to date indicates that celecoxib is a safe and effective therapeutic modality for the management of arthritis and pain.

Analgesics↗
PubMed1999

[Budd-Chiari syndrome due to membranous obstruction of the inferior vena cava of congenital origin. Ten-year follow-up after radiologic treatment].

We report a case of Budd-Chiari syndrome due to membranous obstruction of the inferior vena cava with a congenital malformation composed of a left inferior vena cava at the sub-renal level with an azygo-caval continuation without a retrohepatic segment of the inferior vena cava. To our knowledge, this is the first report of this association. The congenital venous malformation suggests a congenital etiology to the inferior vena cava membrane. The membranous obstruction was treated by percutaneous transluminal angioplasty. During the 10-year follow-up, there was no recurrence of the membranous obstruction as seen with Doppler ultrasound and magnetic resonance imaging.

Adult↗
PubMed1998

Splenorenal shunt blood flow by transit-time ultrasound as an index of collateral circulation in portal hypertensive rats.

The aim of this study was to develop a technique that could serve as an index of portosystemic shunt (PSS) blood flow in portal hypertensive rats whose main shunt is the splenorenal shunt (SRS). The main hemodynamic measurements performed were: SRS blood flow by the transit-time ultrasound (TTU) method, percentage of PSS, and regional blood flows by the microsphere method. We determined the accuracy and reproducibility of SRS blood flow measurements under baseline and pharmacological (octreotide) conditions. SRS blood flow was compared with other hemodynamic characteristics. Two models of portal hypertension were used: secondary biliary and dimethylnitrosamine cirrhosis. The SRS blood flow was correlated with mesenteric (r = .76; P < .001) and splenic (r = .67; P < .01) PSS percentages. The intra- and interobserver agreements for SRS blood flow were excellent: ric = .99 and ric = .98, respectively. SRS blood flow was six times higher in portal hypertensive rats (0.6 +/- 0.7 mL . min-1 . 100 g-1) than in sham rats (0.1 +/- 0.1 mL . min-1 . 100 g-1 [P < .01]). Octreotide significantly decreased SRS blood flow but not mesenteric or splenic PSS percentages. SRS is the main PSS in rats. The measurement of SRS blood flow by TTU is accurate and reproducible. This method can be used to identify new mechanisms in hemodynamic studies that differ from those identified by the measurement of the percentage of PSS by the microsphere method, especially in pharmacological studies.

Animals↗
PubMed1998

Antifibrotic and hemodynamic effects of the early and chronic administration of octreotide in two models of liver fibrosis in rats.

The aim of this study was to assess the effect of the early and chronic administration of octreotide in the prevention of hepatic fibrosis and portal hypertension (PHT). Two experimental models of liver fibrosis caused by bile duct ligation (BDL) or CCl4 were divided into 4 rat groups: sham, placebo, and octreotide (10 and 100 micrograms/kg twice daily, subcutaneously). Liver fibrosis was assessed by the area of fibrosis (image analysis), liver hydroxyproline and fibronectin mRNA contents, and serum hyaluronate. Systemic and splanchnic hemodynamic changes were also evaluated, including the splenorenal shunt blood flow by the transit-time ultrasound (TTU) technique. In both models, splenorenal shunt blood flow was significantly lower in the octreotide groups than in the placebo group (P <.05), while portal pressure was not significantly decreased. There was a significant decrease in fibrosis by octreotide in the CCl4 model only: area of fibrosis: 13.9% +/- 3.7% vs. 9.8% +/- 2.5% (P <.01), hydroxyproline: 1.8 +/- 0.6 vs. 1.3 +/- 0.4 mg/g wet liver (P <.05), respectively, placebo vs. octreotide 10 micrograms/kg. There was a significant correlation between the area of fibrosis and hydroxyproline liver content (r =.87 in the biliary model and r =.91 in the CCl4 model; P <.0001). The early and chronic administration of octreotide prevents the development of portocollateral blood flow without reducing portal pressure in two models of liver fibrosis and the development of liver fibrosis in the CCl4 model.

Animals↗
PubMed1998

Effects of long-term administration of interferon alpha in two models of liver fibrosis in rats.

BACKGROUND/AIMS: The aim of this study was to assess the effect of the early and chronic administration of interferon alpha in the prevention of hepatic fibrosis and portal hypertension. METHODS: Rats with liver fibrosis due to bile duct ligation or CCl4 were divided into three groups: sham, placebo and interferon alpha2a 100,000 UI/day. Liver fibrosis was assessed by the area of fibrosis (image analysis), liver hydroxyproline and mRNA (fibronectin, procollagen alpha2(I)) contents, and serum hyaluronate. Systemic and splanchnic hemodynamics were also evaluated. RESULTS: Interferon alpha significantly decreased fibrosis in the CCl4 model only: area of fibrosis: 13.9+/-3.7 vs 10.5+/-3.3% (p<0.05), hydroxyproline: 1.8+/-0.6 vs 1.2+/-0.2 mg/g wet liver (p<0.001), respectively placebo vs interferon alpha. There was a significant correlation between the area of fibrosis and hydroxyproline liver content (r=0.77 in the biliary model and r=0.87 in the CCl4 model, p<0.0001). Interferon decreased spleno-renal shunt blood flow (2.0+/-1.8 vs 0.9+/-0.7 ml/min; p<0.05) but not portal pressure in the CCl4 model. No significant effects were observed in rats with biliary fibrosis. CONCLUSIONS: The early and chronic administration of interferon alpha prevents the development of liver fibrosis and porto-collateral circulation in the CCl4 model but not in the biliary model. However, the antifibrotic effects of interferon need to be confirmed in further studies.

Alanine Transaminase↗
PubMed1998

Advantages of Sabatier for extended duration manned missions.

As manned space missions become longer and go farther away (i.e., Mars missions), the cost of resupply missions becomes substantial and even impractical. In order to reduce the logistics penalty for air revitalization in manned spacecraft, breathing oxygen (O2) must be recovered from metabolic carbon dioxide (CO2). The Sabatier CO2 reduction system is a key component of an integrated air revitalization system. The heart of the Sabatier system is the chemical catalyst bed that reacts carbon dioxide with hydrogen to form methane and water. Product water from a Sabatier subsystem would positively affect the current International Space Station (ISS) water balance and Mars missions would also benefit from the use of product methane as a propellant. This article focuses on the potential benefits of using the Sabatier subsystem for ISS and potential Mars mission applications.

Air Conditioning↗