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Biomedical subjects

J C Fernández

Publications and source records attributed to J C Fernández.

At least 19 recordsLinked to original sources
PubMed2006

Theory of laser acceleration of light-ion beams from interaction of ultrahigh-intensity lasers with layered targets.

Experiments at the LANL Trident facility demonstrated the production of monoenergetic ion beams from the interaction of an ultraintense laser with a target comprising a heavy ion substrate and thin layer of light ions. An analytic model is obtained that predicts how the mean energy and quality of monoenergetic ion beams and the energy of substrate ions vary with substrate material and light-ion layer composition and thickness. Dimensionless parameters controlling the dynamics are derived and the model is validated with particle-in-cell simulations and experimental data.

Journal Article↗
PubMed2006

Laser acceleration of quasi-monoenergetic MeV ion beams.

Acceleration of particles by intense laser-plasma interactions represents a rapidly evolving field of interest, as highlighted by the recent demonstration of laser-driven relativistic beams of monoenergetic electrons. Ultrahigh-intensity lasers can produce accelerating fields of 10 TV m(-1) (1 TV = 10(12) V), surpassing those in conventional accelerators by six orders of magnitude. Laser-driven ions with energies of several MeV per nucleon have also been produced. Such ion beams exhibit unprecedented characteristics--short pulse lengths, high currents and low transverse emittance--but their exponential energy spectra have almost 100% energy spread. This large energy spread, which is a consequence of the experimental conditions used to date, remains the biggest impediment to the wider use of this technology. Here we report the production of quasi-monoenergetic laser-driven C5+ ions with a vastly reduced energy spread of 17%. The ions have a mean energy of 3 MeV per nucleon (full-width at half-maximum approximately 0.5 MeV per nucleon) and a longitudinal emittance of less than 2 x 10(-6) eV s for pulse durations shorter than 1 ps. Such laser-driven, high-current, quasi-monoenergetic ion sources may enable significant advances in the development of compact MeV ion accelerators, new diagnostics, medical physics, inertial confinement fusion and fast ignition.

Journal Article↗
PubMed2006

Effects of policosanol on patients with ischemic stroke: a pilot open study.

Stroke is a major health problem worldwide. Its pharmacological management includes thrombolytic therapy for the acute phase and antiplatelet drugs for stroke recovery and prevention. Statins can help in the acute phase and in preventing stroke in secondary prevention patients. Policosanol is a cholesterol-lowering drug with concomitant antiplatelet effects, with protective effects in stroke models. This observational study investigated the effects of policosanol (20 mg/day) administered during the acute phase and for 5 years later on the neurological recovery of patients with ischemic stroke treated with antiplatelets and vitamins. After hospital discharge, patients were followed up every 3 (first year) and 6 (thereafter) months. Neurological improvement was assessed with the modified Canadian Neurological Scale. Adverse events were recorded. Fifty patients were included; all completed the study. Neurological score improved throughout the study. No patient died, and most [40 (80.0%)] did not experience new vascular events; only one (2.0%) suffered a new stroke, and two (4.0%) suffered more than one transient ischemic attack. The time to the first recurrent event was 46.2 months. Policosanol persistently lowered serum total cholesterol, with such reduction correlating with the neurological improvement (R = 0.995253301). Triglycerides were unchanged. Treatment was well tolerated. Policosanol administered to patients suffering ischemic stroke treated with aspirin and vitamins showed good results on neurological outcomes and recurrent events. This study, however, has limitations, since it was open and uncontrolled, and patients also consumed aspirin and vitamins. New randomized, controlled studies are needed to assess the usefulness of policosanol in stroke management.

Aged↗
PubMed2005

Comparison of laser ion acceleration from the front and rear surfaces of thin foils.

The comparative efficiency and beam characteristics of high-energy ions generated by high-intensity short-pulse lasers (approximately 1-6 x 10(19) W/cm2) from both the front and rear surfaces of thin metal foils have been measured under identical conditions. Using direct beam measurements and nuclear activation techniques, we find that rear-surface acceleration produces higher energy particles with smaller divergence and a higher efficiency than front-surface acceleration. Our observations are well reproduced by realistic particle-in-cell simulations, and we predict optimal criteria for future applications.

Journal Article↗
PubMed2001

Observation of stimulated electron-acoustic-wave scattering.

A diffraction-limited laser interacts with a plasma whose conditions are uniform on the scale of the focused laser spot. Two distinct, narrow waves are observed in the backscattered spectrum with phase velocities of v(phi)/v(e) = 1.4+/-0.08 and 4.2+/-0.1, where v(e) is the electron thermal speed. The high-velocity wave is ordinary stimulated Raman scattering (SRS) from a Langmuir wave. The low-velocity wave corresponds to stimulated scattering from an electron-acoustic wave (SEAS), and implies strong electron trapping. Previous SRS data from low-density plasmas are reinterpreted in terms of SEAS.

Journal Article↗
PubMed2001

Effects of policosanol in older patients with type II hypercholesterolemia and high coronary risk.

BACKGROUND: The present study was undertaken to investigate the effects of policosanol in older patients with type II hypercholesterolemia and more than one concomitant atherosclerotic risk factor. METHODS: After 6 weeks on a lipid-lowering diet, 179 patients randomly received a placebo or policosanol at doses of 5 followed by 10 mg per day for successive 12-week periods of each dose. Policosanol (5 and 10 mg/d) significantly (p < .001) reduced low-density lipoprotein cholesterol (LDL-C; 16.9% and 24.4%, respectively) and total cholesterol (TC; 12.8% and 16.2%, respectively), while significantly (p < .01) increasing (p < .001) high-density lipoprotein cholesterol (HDL-C) by 14.6% and 29.1%, respectively. RESULTS: Policosanol significantly decreased (p < .01) the ratios of LDL-C to HDL-C (29.1%) and TC to HDL-C (28%) at study completion, although triglycerides remained unchanged. Policosanol, but not the placebo, significantly improved (p .01) cardiovascular capacity, which was assessed using the Specific Activity Scale. No serious adverse experiences occurred in policosanol patients (p < .01), compared with seven adverse experiences (7.9%) reported by placebo patients. CONCLUSIONS: This study shows that policosanol is effective, safe, and well tolerated in older hypercholesterolemic patients.

Aged↗
PubMed2000

Effects of policosanol treatment on the susceptibility of low density lipoprotein (LDL) isolated from healthy volunteers to oxidative modification in vitro.

AIMS: The aim of this study was to investigate the effect of policosanol on the susceptibility of LDL-C to in vitro lipid peroxidation in human healthy volunteers. METHODS: The effect of policosanol (5 and 10 mg day(-1) on LDL-C oxidation was studied in a double-blind, randomized, placebo-controlled trial conducted in 69 subjects. LDL-C samples isolated at baseline and after 8 weeks were subjected to in vitro tests of LDL-C oxidation. We tested the susceptibility of LDL-C to lipid peroxidation in a cell-free system by the addition of copper ions as well as in a more physiological system, macrophage-mediated oxidation. RESULTS: At baseline all groups were well matched regarding all variables. After 8 weeks of therapy policosanol administered at 5 and 10 mg, significantly and in a dose-dependent manner increased the lag phase of conjugated diene generation (mean +/- s.d.) from 83.79+/-29.16 min to 94.90+/-25.50 min (5 mg day(-1)) and from 82.74+/-17.16 min to 129.89+/-35.71 min (10 mg day(-1)), while in the placebo group LDL-C oxidation did not change significantly. Policosanol (10 mg day(-1)), but not placebo, significantly decreased the rate of conjugated diene generation. Comparison with placebo after therapy also showed significant differences. Macrophage mediated-oxidation was also inhibited by policosanol as evident by measuring thiobarbituric acid reactive substances (TBARS). Policosanol (10 mg day(-1)) significantly lowered malondialdehyde (MDA) generation from 8.50+/-0.91 to 5.76+/- 1.01 nmol mg(-1) protein. Comparison with placebo after 5 and 10 mg day(-1) showed significant differences. Policosanol significantly lowered total cholesterol by 10.5% (5 mg day(-1)) and 12.4% (10 mg day(-1)) and LDL-C by 16.7% and 20.2%, respectively. Also, policosanol (10 mg day(-1)) increased HDL-C by 15.2%. Five subjects withdrew from the study, none because of adverse experiences. No clinical or blood biochemical drug-related disturbances were found. CONCLUSIONS: The present study demonstrated that policosanol administered within its therapeutic dosage for lowering cholesterol (5 and 10 mg day(-1)), decreased the susceptibility of LDL-C to lipid peroxidation in vitro.

Adult↗
PubMed2000

Effects of policosanol on postmenopausal women with type II hypercholesterolemia.

This randomized, double-blind, placebo-controlled study was conducted to investigate the efficacy, safety and tolerability of policosanol, a cholesterol-lowering drug purified from sugar-cane wax, in postmenopausal women with type II hypercholesterolemia. A total of 244 women who had experienced the menopause and showed elevated serum total cholesterol and low-density lipoprotein cholesterol (LDL-C) levels despite 6 weeks on a standard lipid-lowering diet were randomized to receive placebo or policosanol 5 mg/day for 12 weeks, after which the dose was doubled to 10 mg/day for the next 12 weeks. Policosanol (5 and 10 mg/day) significantly lowered LDL-C levels (17.7% and 25.2%, respectively) and total cholesterol (12.6% and 16.7%, respectively), as well as the ratios of LDL-C to high-density lipoprotein cholesterol (HDL-C) (17.0% and 29.3%, respectively) and total cholesterol to HDL-C (16.7% and 27.2%, respectively), compared to the baseline and placebo; at the same time, policosanol significantly raised HDL-C levels by 16.5% and 29.3%, respectively. The drug was safe and well tolerated. No drug-related adverse events were observed, and even the extent of adverse events was less in the policosanol group than in the placebo group. Four serious adverse events occurred in the placebo group (one myocardial infarction, two cases of hypertensive status and one surgical intervention) compared to none in the policosanol group. In conclusion, policosanol is effective, safe and well tolerated in hypercholesterolemic postmenopausal women.

Aged↗
PubMed1999

A double-blind, placebo-controlled study of the effects of policosanol in patients with intermittent claudication.

This study was undertaken to evaluate the efficacy and tolerability of policosanol, a new cholesterol-lowering drug with concomitant antiplatelet effects, in patients with intermittent claudication. After a baseline period of 6 weeks, 62 patients were randomized to receive, under double-blind conditions, either placebo (31 patients) or policosanol (31), 10 mg twice daily. Walking distances in a treadmill (constant speed 3.2 km/hr, slope 10 degrees) were assessed before and after 6 months of treatment. Both groups were similar at randomization. Policosanol increased significantly (p < 0.01) the initial claudication distance from 132.5+/-13.5 m (baseline) to 205.7+/-36.3 m (after therapy) and the absolute claudication distance (p<0.0001) from 229.5+/-22.0 m to 365.4+/-46.9 m; meanwhile both variables remained unchanged in the placebo group (p<0.05). The reduction of lower limb symptoms showed a greater benefit in the policosanol group. There was no significant change in either group in the ankle/arm pressure ratio. The treatment was well tolerated. There were 10 discontinuations (seven placebo, three policosanol) from the study. Six withdrawals occurred because of adverse events (AE); all were in placebo patients. There were five serious vascular AEs in the placebo group but none in the policosanol group (p<0.05). Overall, 12/31 (38.7%) placebo patients and 3/31 (9.7%) policosanol patients experienced AEs after randomization, which showed a lesser incidence of AEs in the policosanol group (p<0.01). The present study demonstrates a beneficial effect of policosanol in patients with intermittent claudication.

Adult↗
PubMed1999

Effects of policosanol and pravastatin on lipid profile, platelet aggregation and endothelemia in older hypercholesterolemic patients.

This randomized, double-blind study was undertaken to compare the effects of policosanol and pravastatin administered at 10 mg/day on lipid profile, platelet aggregation and endothelemia in older patients with type II hypercholesterolemia and high coronary risk. After 6 weeks on a lipid-lowering diet, patients with low-density lipoprotein (LDL) cholesterol levels > 3.4 mmol/l were randomized to receive, under double-blind conditions, policosanol or pravastatin 10 mg tablets that were taken with the evening meal for 8 weeks. Policosanol significantly (p < 0.00001) lowered LDL-cholesterol (19.3%), total cholesterol (13.9%) and the ratios of LDL-cholesterol/high-density lipoprotein (HDL)-cholesterol (28.3%) and total cholesterol/HDL-cholesterol (24.4%). Pravastatin significantly (p < 0.00001) lowered LDL-cholesterol (15.6%), total cholesterol (11.8%) and the ratios (p < 0.0001) of LDL-cholesterol/HDL-cholesterol (18.9%) and total cholesterol/HDL-cholesterol (15.7%). Policosanol, but not pravastatin, significantly increased (p < 0.001) levels of HDL-cholesterol (18.4%) and reduced (p < 0.01) triglycerides (14.1%). Policosanol was more effective (p < 0.05) than pravastatin in inhibiting platelet aggregation induced by all agonists and it significantly reduced (p < 0.0001) platelet aggregation induced by arachidonic acid at 1.5 and 3 mmol/l by 42.2% and 69.5%, respectively, platelet aggregation induced by collagen 0.5 microgram/ml (p < 0.05) (16.6%) and that induced by adenosine diphosphate 1 mumol/l (p < 0.01) (20.3%). Pravastatin significantly reduced (p < 0.001) (27%) only platelet aggregation induced by arachidonic acid 3 mmol/l. Both drugs significantly decreased (p < 0.00001) endothelemia levels but final values were significantly lower (p < 0.001) in the policosanol than in the pravastatin group. Both treatments were safe and well tolerated. Pravastatin significantly (p < 0.01) increased serum levels of alanine amine transferase but individual values remained within normal. Two patients on pravastatin discontinued the study because of adverse experiences (myocardial infarction and jaundice, respectively). In conclusion, the effects of policosanol (10 mg/day) on lipid profile, platelet aggregation and endothelemia in older patients with type II hypercholesterolemia and high coronary risk are more favorable than those induced by the same doses of pravastatin.

Aged↗
PubMed1997

Effect of topical anti-inflammatory drugs on epithelial cell-induced eosinophil survival and GM-CSF secretion.

Topical anti-inflammatory drugs decrease eosinophil infiltration. This action may be due to an effect on the release of epithelial cell products responsible for promoting eosinophil survival. We investigated the effect of fluticasone propionate, budesonide, beclomethasone dipropionate and nedocromil sodium on the release of granulocyte/macrophage colony-stimulating factor (GM-CSF) and on eosinophil survival induced by secretions from cultured nasal epithelial cells. Human epithelial cell-conditioned media (HECM) were generated by cultured epithelial cells obtained from healthy subjects undergoing corrective nasal surgery. Normodense eosinophils isolated from peripheral blood were incubated with HECM generated with and without the drugs. All of the drugs tested inhibited eosinophil survival, and response was dose-dependent. Fluticasone propionate had the highest inhibitory potency (25% inhibitory concentration (IC25) 1x10(-9) M), followed by budesonide (IC25 3.3x10(-8) M), beclomethasone dipropionate (IC25 1.5x10(-6) M), and nedocromil sodium IC25 5x10(-6) M). Likewise, fluticasone was the strongest steroid in inhibiting release of GM-CSF (IC25 8.4x10(-11) M), followed by budesonide (IC25 2x10(-9) M), beclomethasone dipropionate (IC25 13x10(-8) M), and nedocromil sodium (IC25 >10(-5) M). A significant correlation was found between both inhibitory effects (r=0.955; p<0.05). Topical anti-inflammatory drugs may decrease eosinophil survival by abrogating the promoting effect of epithelial cells. These drugs may exert part of their therapeutic effect by modulating GM-CSF release. The following rank of potency was observed: fluticasone propionate > budesonide > beclomethasone dipropionate > nedocromil sodium. The study of the interaction between epithelial cells and eosinophils may be a useful method for investigating and comparing the potency of topical drugs.

Administration, Topical↗
PubMed1995

Pollen allergy in the Bilbao area (European Atlantic seaboard climate): pollination forecasting methods.

Forecasting pollination can help the allergist to establish the appropriate treatment and advice for patients. Based on previous studies, we have related the climate variables with the grass pollen counts in the search for pollination predictors. By relating the meteorological data of the temperature recorded every 6 h and of the rainfall in hourly periods, together with the daily pollen counts obtained by the Hirst volumetric system, over a period of 3 years, we have tried to predict the start, duration and severity of the grass pollination, as well as the days of peak pollination. We have established a relationship by means of a polynomic regression originating from the mean cumulated temperature higher than 9 degrees C [R2 = 0.927 (P = 0.0001)], with the pollination season starting from 300 degrees C and the maximum peak at 356 degrees C, in the 3 years of the study. During the days of pollination, peaks higher than 50 grains/m3 coincide with average daily temperatures of 18.7 +/- 3 and lower than 50 grains/m3 with temperatures of 16.8 +/- 3 (significant to 95%). The duration of the pollination is influenced by the cumulated average temperatures (from 800 to 900 degrees C) and especially by precipitation at the start of and during pollination. In order to forecast grass pollination, the cumulated average temperatures are useful, starting from a basal (9 degrees C), pollination begins when this sum is greater than 300 degrees C, whereas when 800 degrees C is reached and depending on the rainfall during the season, pollination will end.(ABSTRACT TRUNCATED AT 250 WORDS)

Climate↗
PubMed1995

Treatment of hypercholesterolemia in NIDDM with policosanol.

OBJECTIVE: To determine whether elevated levels of cholesterol and low-density lipoprotein (LDL) cholesterol in non-insulin-dependent diabetes mellitus (NIDDM) patients could be decreased by policosanol, a new cholesterol-lowering drug. NIDDM predisposes patients to coronary artery disease (CAD) through the direct action of hyperglycemia on the arteries as well as the dyslipidemia induced by NIDDM. RESEARCH DESIGN AND METHODS: This double-blind placebo-controlled trial was performed in 29 patients with NIDDM and hypercholesterolemia. After stable glycemic control was achieved by diet and/or oral hypoglycemic drugs, patients were instructed to follow a cholesterol-lowering diet for 6 weeks. Patients who met entry criteria received, under double-blind conditions, policosanol (5 mg) or placebo tablets twice a day for 12 weeks. RESULTS: Policosanol (10 mg/day) significantly reduced total cholesterol by 17.5% and LDL cholesterol by 21.8% compared with baseline and placebo. Furthermore, high-density lipoprotein (HDL) cholesterol was raised by 11.3% (not significant), and triglycerides showed a statistically nonsignificant decrease of 6.6%. These changes in lipid profile were similar to those induced by policosanol in nondiabetic patients with type II hyperlipoproteinemia. CONCLUSIONS: Glycemic control was unaffected by treatment. No clinically or biochemically adverse effects attributable to treatment were observed. Only one patient (placebo) withdrew from the trial because of an adverse experience (erythema). We concluded that policosanol is effective and safe in patients with NIDDM and hypercholesterolemia.

Anticholesteremic Agents↗
PubMed1994

Effects of successive dose increases of policosanol on the lipid profile of patients with type II hypercholesterolaemia and tolerability to treatment.

This randomized, double-blind, placebo-controlled study was conducted in 22 patients with type II primary hypercholesterolaemia to investigate the efficacy, safety and tolerability of two successive dose increases of policosanol. Patients with elevated serum low-density-lipoprotein cholesterol (LDL-C) and total cholesterol after a diet-only period received randomly, under double-blind conditions, placebo or policosanol at 5 mg once-a-day for 8 weeks. After this period, dosage was doubled to 5 mg twice-a-day for the next 8 weeks and then again doubled to 10 mg twice-a-day. It was found that the LDL-C was reduced significantly by 11.3%, 21.9% and 31.2%, while total cholesterol was also reduced significantly by 8%, 14.1% and 23% respectively in these three periods. Serum high-density-lipoprotein cholesterol (HDL-C) was increased by 7.8%, 7.2% and 8.7%, respectively, while in the placebo group a downward shift was observed. The LDL-C to HDL-C ratio was reduced significantly by 15.3%, 25.6% and 34.6%, while the total cholesterol to HDL-C ratio was also reduced significantly by 12.5%, 18.4% and 27.1%, respectively. Triglycerides and VLDL-C values did not change significantly. The reduction of LDL-C, total cholesterol, LDL-C to HDL-C, and total cholesterol to HDL-C ratios showed a dependence on the successive dose increases. Policosanol was very well tolerated. No patient discontinued the trial. No disturbances of clinical or blood biochemistry variables attributable to treatment were observed. Adverse effects reported were mild and transient, and no significant differences between groups were found.

Adult↗
PubMed1993

DR7 and DQ2 are positively associated with immunoglobulin-E response to the main antigen of olive pollen (Ole e I) in allergic patients.

We have studied the relationship between HLA class II haplotypes and alleles, and the IgE antibody response to a highly purified allergen, Ole e I, in allergic patients. Ole e I, is the major antigen from the pollen of olive tree that grows mainly in the Mediterranean. Genomic DNA typing was performed in 40 unrelated patients with seasonal allergic pollenosis who had specific IgE antibodies against Ole e I, detected by double-antibody radioimmunoassay. HLA-DRB and -DQB loci were analyzed by PCR-SSO and RFLP. Phenotypic frequencies were compared with those of 179 healthy unrelated individuals. Significant increases in the phenotypic frequencies of DR7 (pf = 67.5% vs 31.3% in the control population, pc = 0.0023) and DQ2 (pf = 90.0% vs 48.0%, pc = 0.0003) were found, indicating an association between DRB1*0701/2, DQB1*0201 alleles and the IgE antibody response to Ole e I. This is the first time that the HLA-DQ gene has been associated with a positive allergic response.

Allergens↗
PubMed1992

Eosinophil as antigen-presenting cell: activation of T cell clones and T cell hybridoma by eosinophils after antigen processing.

We have studied the role of murine eosinophils as antigen-presenting cells (APC). Eosinophils have several characteristics that support the hypothesis of its function as potential APC: they have phagocytic capacity, express adhesion molecules and major histocompatibility complex (MHC) class II antigens and can produce and release interleukin-1 (IL-1). We have obtained several T cell clones specific for Mesocestoides corti antigens and used T cell hybridoma specific for ovalbumin (OVA) to test this hypothesis. Granulocyte-macrophage colony-stimulating factor-activated pure eosinophils (99.9%), express class II antigens and are able to present M. corti antigens to specific T cell clones or OVA to T cell hybridoma 3DO 11.10, inducing the proliferation of T cell clones and IL-2 release by the T cell hybridoma. Proliferation of T cells clones is dependent on the number of eosinophils used as APC. We have compared the efficiency of the same number of macrophages and eosinophils as APC, and have found that macrophages are more efficient than eosinophils. Lysosomotropic agents, such as chloroquine and ammonium chloride, that inhibit antigen processing, impaired eosinophil presentation. This presentation is restricted by MHC class II and inhibited by anti-I-Ad monoclonal antibody. The present study provides clear evidence of APC function for eosinophils. Our investigation points to a new role for eosinophils in the immune response.

Ammonium Chloride↗