Biomedical subjects

G Ruiz

Publications and source records attributed to G Ruiz.

At least 19 recordsLinked to original sources

PubMed2006

[Consequences of glaucoma on circadian and central visual systems].

Glaucoma is a chronic optic neuropathy leading to a degeneration of retinal ganglion cells. There is accumulating evidence that glaucomatous damage extends from retinal ganglion cells to vision centers in the brain. Degenerative changes are observed in magnocellular, parvocellular, and koniocellular pathways in the lateral geniculate nucleus, and these changes are related to intraocular pressure and the severity of optic nerve damage. In addition, recent studies show that there are also changes in the visual cortex in relation to varying degrees of retinal ganglion cell loss. In a rat model of glaucoma, we have recently demonstrated a reduction of retinal projections of retinal ganglion cells, not only on the visual system but also on the suprachiasmatic nucleus. Human studies suggest that the ganglion cell degeneration caused by glaucoma could lead to a lesion of the retinohypothalamic tract, which permits the synchronization of circadian rhythms.

Brain Diseases↗

PubMed2006

A hydrogen-based variable-gain controller for anaerobic digestion processes.

An easy-to-implement controller based on gas phase measurements for anaerobic digestion processes was developed. The controller is based on the indirect control of COD in the effluent by means of controlling the hydrogen concentration in the biogas. The fast response of hydrogen under destabilizations, such as those caused by overloads, guarantees an early actuation on the system before it destabilizes. The controller is designed such that it brings the anaerobic digestion process to maximum capacity by pushing it to maximum methane production as long as hydrogen remains low. Experiments have been conducted to test the controller under organic over- and underload situations and promising performance was achieved. Further experiments must be carried out to validate the controller under a wider spectrum of situations to enable its robust industrial application.

Anaerobiosis↗

PubMed2005

Nitrification-denitrification via nitrite accumulation for nitrogen removal from wastewaters.

The biological nitrification-denitrification process is used extensively for removal of ammonia nitrogen from wastewaters. Saves in aeration, organic matter (for denitrification) and surplus sludge are achievable if nitrite accumulation is possible in the nitrification step. In this paper, operational parameters were studied for each process for maximum nitrite accumulation in the nitrification step and nitrite adaptation in the denitrification step. Nitrite accumulation during nitrification can be controlled by the dissolved oxygen (DO) concentration, presenting a maximum of 65% at around 0.7 mg DO/L. Denitrification can be adapted to nitrite and the process is stable if nitrite in the reactor is keep low. The performance of a continuous stirred tank reactor (CSTR) and an up flow sludge blanket reactor (USB) were compared. Once the operational parameters were established, a CSTR for nitrification and an USB reactor for denitrification were operated in series for 25 days. The process was stable and a steady state was maintained for 20 days, and 93.5% of overall nitrogen removal was achieved in the nitrification-denitrification via the nitrite process.

Ammonia↗

PubMed2005

An integrated system to remote monitor and control anaerobic wastewater treatment plants through the internet.

The TELEMAC project brings new methodologies from the Information and Science Technologies field to the world of water treatment. TELEMAC offers an advanced remote management system which adapts to most of the anaerobic wastewater treatment plants that do not benefit from a local expert in wastewater treatment. The TELEMAC system takes advantage of new sensors to better monitor the process dynamics and to run automatic controllers that stabilise the treatment plant, meet the depollution requirements and provide a biogas quality suitable for cogeneration. If the automatic system detects a failure which cannot be solved automatically or locally by a technician, then an expert from the TELEMAC Control Centre is contacted via the internet and manages the problem.

Automation↗

PubMed2004

Quantitation of human immunodeficiency virus type 1 RNA loads in cervicovaginal secretions in pregnant women and relationship between viral loads in the genital tract and blood.

The purpose of this study was to analyze the quantitation of the human immunodeficiency virus type 1 RNA (HIV-1 RNA) in the genital tract of HIV-1-infected pregnant women and to evaluate a possible correlation with the viral load in blood plasma (Spearman's rank correlation coefficient). A total of 38 each of cervical, vaginal, and blood samples from 38 women were obtained during the third trimester of pregnancy for quantitation of the HIV-1 RNA load. Viral loads were determined by reverse transcription-polymerase chain reaction. The HIV-1 RNA viral load was detectable in 29 of the 38 (76.3%) blood samples, in 6 of the 38 (15.7%) cervical secretion samples, and in 8 of the 38 (21%) vaginal secretion samples. Overall, the correlation between the HIV-1 RNA viral load in the blood plasma and in cervical secretion samples was 0.51 ( P<0.001). However, the correlation disappeared ( r=0.27) when three patients with high blood plasma viral loads were eliminated from the statistical study. The viral load in the vaginal secretions did not correlate with that in the blood samples ( r=0.26). There were two cases in which HIV-1 RNA was undetectable in the blood and cervix but was detectable in vaginal secretions: one woman had 220 copies/ml and the other 68 copies/ml. These results suggest that pregnant women with undetectable viral loads in blood plasma are still at risk of transmitting the virus vertically during vaginal delivery. Because of this, antiretroviral prophylaxis during vaginal delivery must be administered to HIV-1-infected women and their newborns, regardless of the mother's viral load in plasma. In conclusion, quantification of cervicovaginal levels of HIV-1 may represent a useful tool for assessing the individual risk associated with a vaginal delivery and for guiding decisions about whether a scheduled caesarean should be recommended.

Adult↗

PubMed2003

Local density approach for modeling fluids with density-dependent interactions.

In a recent paper [Phys. Rev. Lett. 86, 2038 (2001)] a simple fluid with a particular density-dependent pair potential was shown to exhibit, together with the vapor-liquid transition, a liquid-liquid phase separation and it was evidenced that, in order to adequately define the correct boundaries of stability, a simulation procedure based on the use of local densities had to be devised. It was found that for certain thermodynamic states the potential drives the system toward a phase separation that is otherwise frustrated by the change in the interactions induced by density fluctuations. Therefore, when integral equations or global density simulations are used, the critical points estimated from the thermodynamics are not associated with divergent correlations and vice versa. Here, we will explore in depth this fluid and introduce a detailed account of the proposed local density simulation technique. The results presented bear general significance for density-dependent potentials, like those of liquid metals or charge-stabilized colloids.

Journal Article↗

PubMed2003

Nitrification with high nitrite accumulation for the treatment of wastewater with high ammonia concentration.

The objective of this paper was to determine the best conditions for partial nitrification with nitrite accumulation of simulated industrial wastewater with high ammonia concentration, lowering the total oxygen needed in the nitrification step, which may mean great saving in aeration. Dissolved oxygen (DO) concentration and pH were selected as operational parameters to study the possibility of nitrite accumulation not affecting overall ammonia removal. A 2.5L activated sludge reactor was operated in nitrification mode, feeding a synthetic wastewater simulating an industrial wastewater with high ammonia concentration. During the start-up a pH of 7.85 and a DO of 5.5mg/L were used. The reactor was operated until stable operation was achieved at final nitrogen loading rate (NLR) of 3.3kgN- NH(4)(+)/m(3)d with an influent ammonia concentration of 610mg N-NH(4)(+)/L. The influence of pH was studied in continuous operation in the range of 6.15-9.05, changing the reactor pH in steps until ammonia accumulation (complete nitrification inhibition) took place. The influence of DO was studied in the same mode, changing the DO in steps from 5.5 to 0.5mg/L. The pH was not a useful operational parameter in order to accumulate nitrite, because in the range of pH 6.45-8.95 complete nitrification to nitrate occurs. At pH lower than 6.45 and higher than 8.95 complete inhibition of nitrification takes place. Setting DO concentration in the reactor at 0.7mg/L, it was possible to accumulate more than 65% of the loaded ammonia nitrogen as nitrite with a 98% ammonia conversion. Below 0.5mg/L of DO ammonia was accumulated and over a DO of 1.7mg/L complete nitrification to nitrate was achieved. In conclusion, it is possible under the conditions of this study, to treat high ammonia synthetic wastewater achieving an accumulation of at least 65% of the loaded nitrogen as nitrite, operating at a DO around 0.7mg/L. This represents a reduction close to 20% in the oxygen necessary, and therefore a considerable saving in aeration.

Ammonia↗

PubMed2003

Latent inhibition disruption by MK-801 in a conditioned taste-aversion paradigm.

N-Methyl-D-aspartate (NMDA) receptors appear to be involved in CS processing and memory consolidation. The present paper analyzed the effect of the non-competitive NMDA receptor antagonist Dizocilpine maleate (MK-801) on Latent Inhibition (LI)-retarded learning of a CS-US association after to-be-CS preexposures at time of testing, using Wistar rats as experimental subjects. If NMDA receptors are involved in CS processing, MK-801 administration should affect LI. In fact, previous experiments revealed that a 2.0mg/kg MK-801 dose, administered 20 h before preexposure and conditioning, abolished LI in a conditioned taste-aversion paradigm. In the present paper, MK-801 (0.2 mg/kg) was either injected after preexposure, after conditioning, or after both preexposure and conditioning stages. LI was abolished when MK-801 was injected after preexposure, but not when it was injected after conditioning. These results support the role of NMDA receptors in CS processing and memory consolidation.

Animals↗

PubMed2003

Osteoarticular tuberculosis in a general hospital during the last decade.

OBJECTIVE: To study clinical features of skeletal tuberculosis diagnosed in our laboratory over the last 10 years. METHODS: We carried out a retrospective observational study of 26 patients with osteoarticular tuberculosis recording clinical and microbiological data. RESULTS: Pain was the main clinical presentation. The median time from the onset of symptoms to the diagnosis was 8 months. Synovial fluid was the most common sample obtained. Bone disease and previous or concurrent pulmonary tuberculosis were the most important predisposing factors. The tuberculin test reaction was positive in 83.3% of the patients. The outcome was favorable in 69% of the patients. Weight-bearing joints were the most commonly involved sites. CONCLUSIONS: A high degree of suspicion is still needed to avoid a delayed diagnosis that might complicate the outcome.

Adult↗

PubMed2002

Altered urinary bladder function in mice lacking the vanilloid receptor TRPV1.

In the urinary bladder, the capsaicin-gated ion channel TRPV1 is expressed both within afferent nerve terminals and within the epithelial cells that line the bladder lumen. To determine the significance of this expression pattern, we analyzed bladder function in mice lacking TRPV1. Compared with wild-type littermates, trpv1(-/-) mice had a higher frequency of low-amplitude, non-voiding bladder contractions. This alteration was accompanied by reductions in both spinal cord signaling and reflex voiding during bladder filling (under anesthesia). In vitro, stretch-evoked ATP release and membrane capacitance changes were diminished in bladders excised from trpv1(-/-) mice, as was hypoosmolality-evoked ATP release from cultured trpv1(-/-) urothelial cells. These findings indicate that TRPV1 participates in normal bladder function and is essential for normal mechanically evoked purinergic signaling by the urothelium.

Acetic Acid↗

PubMed2002

Early diagnosis of recurrent breast cancer with FDG-PET in patients with progressive elevation of serum tumor markers.

BACKGROUND: The aim of this work is to assess the diagnostic value of positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG), in the early detection of tumour recurrence in already treated breast cancer patients in apparent complete remission and with a progressive elevation of tumour markers CEA and/or CA 15.3 without any other clinical or instrumental signs of relapses. METHODS: The author studied 45 women (mean age 58+/-12, range 35-80 years) with histological diagnosis of breast cancer who underwent a tumour marker-guided whole body FDG-PET. All patients were in remission, without any other clinical or instrumental signs of relapses, except for the progressive elevation of CA 15.3 and/or CEA, tested during the follow-up. FDG-PET results were controlled by pathology when histological sampling was possible, by other conventional imaging modalities (US, X-rays, CT, MRI) and/or by clinical follow-up up to 12 months at least. RESULTS: FDG-PET findings were evaluated in 38 patients: 27 resulted positive. Among these 27 PET positive patients 24 were true positive and 3 false positive. Tumour marker guided FDG-PET was also able to discover 3 unknown neoplasms not visualized by other modalities. PET revealed 54 sites of intense focal FDG uptake. The anatomical distribution of these sites was 19 skeleton, 18 lymph node basins, 5 liver, 5 pelvic region, 1 lung, 1 pericardium, 1 pleura, 1 contralateral breast, 2 peritoneum and 1 thyroid bed. Forty-eight of these 54 sites of FDG accumulation were confirmed to be metastases. FDG-PET resulted negative in 11 patients and only in 2 of them the other diagnostic modalities were able to discover metastatic lesions; we had 9 true negative and 2 false positive RESULTS. On the basis of our investigation the performances of tumour marker guided FDG-PET per patient are as follows: sensitivity 92% (24/26), specificity 75% (9/12), positive predictive value 89% (24/27), negative predictive value 82% (9/11), accuracy 87% (33/38). CONCLUSIONS: This study demonstrated the clinical utility of tumour marker-guided PET in the follow-up of breast cancer patients. This diagnostic approach allowed to modify the clinical management in those patients in whom a tumor relapse or unexpected primary neoplasm was discovered.

Adult↗

PubMed2001

Anti-Trypanosoma activity of some natural stilbenoids and synthetic related heterocyclic compounds.

We report the anti-Chagasic activity of the natural dihydrostilbenoid isonotholaenic acid and several simple derivatives, as well as that of some representative compounds of related synthetic series, with basic structures of benzalphthalides, dihydrostilbamides, isoindoles, phthalazin-1-ones, imidazo[2,1-a]isoindoles and pyrimido[2,1-a]isoindoles. The evaluation was performed in vitro on cultures of epimastigote and trypomastigote forms of Trypanosoma cruzi. Some of the tested compounds resulted to be as potent as benznidazole (epimastigotes), and others were shown to be more active than gentian violet (trypomastigotes), used as reference drugs.

Animals↗

PubMed2001

Graphite-teflon composite bienzyme electrodes for the determination of cholesterol in reversed micelles. Application to food samples.

A bienzyme amperometric composite biosensor for the determination of free and total cholesterol in food samples is reported. Cholesterol oxidase and horseradish peroxidase, together with potassium ferrocyanide as a mediator, are incorporated into a graphite-70% Teflon matrix. The compatibility of this biosensor design with predominantly nonaqueous media allows the use of reversed micelles as working medium. The reversed micelles are formed with ethyl acetate as continuous phase (in which cholesterol is soluble), a 4% final concentration of 0.05 mol L(-1) phosphate buffer solution, pH 7.4, as dispersed phase, and 0.1 mol L(-1) AOT as emulsifying agent. Studies on the repeatability of the amperometric response obtained at +0.10 V, with and without regeneration of the electrode surface by polishing, on the useful lifetime of one single biosensor and on the reproducibility in the fabrication of different pellets illustrate the robustness of the biosensor design. Determination of free and total cholesterol in food samples such as butter, lard, and egg yoke was carried out, and the obtained results were advantageously compared with those provided by using a commercial Boehringer test kit.

Biosensing Techniques↗

PubMed2001

Vaccination for protection of retinal ganglion cells against death from glutamate cytotoxicity and ocular hypertension: implications for glaucoma.

Our group recently demonstrated that autoimmune T cells directed against central nervous system-associated myelin antigens protect neurons from secondary degeneration. We further showed that the synthetic peptide copolymer 1 (Cop-1), known to suppress experimental autoimmune encephalomyelitis, can be safely substituted for the natural myelin antigen in both passive and active immunization for neuroprotection of the injured optic nerve. Here we attempted to determine whether similar immunizations are protective from retinal ganglion cell loss resulting from a direct biochemical insult caused, for example, by glutamate (a major mediator of degeneration in acute and chronic optic nerve insults) and in a rat model of ocular hypertension. Passive immunization with T cells reactive to myelin basic protein or active immunization with myelin oligodendrocyte glycoprotein-derived peptide, although neuroprotective after optic nerve injury, was ineffective against glutamate toxicity in mice and rats. In contrast, the number of surviving retinal ganglion cells per square millimeter in glutamate-injected retinas was significantly larger in mice immunized 10 days previously with Cop-1 emulsified in complete Freund's adjuvant than in mice injected with PBS in the same adjuvant (2,133 +/- 270 and 1,329 +/- 121, respectively, mean +/- SEM; P < 0.02). A similar pattern was observed when mice were immunized on the day of glutamate injection (1,777 +/- 101 compared with 1,414 +/- 36; P < 0.05), but not when they were immunized 48 h later. These findings suggest that protection from glutamate toxicity requires reinforcement of the immune system by antigens that are different from those associated with myelin. The use of Cop-1 apparently circumvents this antigen specificity barrier. In the rat ocular hypertension model, which simulates glaucoma, immunization with Cop-1 significantly reduced the retinal ganglion cell loss from 27.8% +/- 6.8% to 4.3% +/- 1.6%, without affecting the intraocular pressure. This study may point the way to a therapy for glaucoma, a neurodegenerative disease of the optic nerve often associated with increased intraocular pressure, as well as for acute and chronic degenerative disorders in which glutamate is a prominent participant.

Adjuvants, Immunologic↗

PubMed2001

Evidence of double criticality in a fluid model with density-dependent interactions.

Evidence of a liquid-liquid equilibrium in simple fluids has recently been exposed for a density-dependent pair potential in the framework of a van der Waals theory. Here this double criticality is investigated by means of computer simulation, a perturbation theory, and integral equation theory. It is found that the critical point estimated from the integral equation thermodynamics is not associated with divergent correlations. To cope with these features, a special simulation procedure, based on the definition of local densities, is devised. Monte Carlo calculations confirm the existence of two critical points, in agreement with the predictions of perturbation theory.

Journal Article↗

PubMed2001

Efficacy and safety of memantine, an NMDA-type open-channel blocker, for reduction of retinal injury associated with experimental glaucoma in rat and monkey.

Glutamatergic excitotoxicity has been implicated as a mechanism for injury in a variety of central nervous system pathologies, including glaucoma. Memantine, an NMDA-type glutamatergic open-channel blocker, has pharmacologic properties that make its efficacy greater under excitotoxic conditions, but lesser under normal conditions. Daily oral dosing for approximately 15 months with 4.0 mg/kg memantine in monkeys yielded plasma concentrations similar to those found in patients who received memantine treatment for Parkinson's disease. This same dose of memantine was not associated with any evidence of an effect on the normal function of the retina and central visual pathways, as indicated by measures of the electroretinogram (ERG) and visually-evoked cortical potential (VECP). Amplitude of the VECP response was reduced in eyes with experimentally induced glaucoma. When compared to vehicle-treated control animals, memantine-treated glaucoma eyes suffered significantly less reduction of VECP amplitude. Preliminary results in a rat model for experimental glaucoma also show that, when compared to control animals, systemic treatment with memantine (10 mg/kg/day) was associated with a significant reduction in glaucoma-induced loss of retinal ganglion cells.

Animals↗

PubMed2001

[Plasmatic concentrations of fibronectin as marker of clinical course among septic patients].

INTRODUCTION: It is difficult to follow up the patients with sepsis because of the underlying pathology or the presence of complications. The attending physician needs to know as soon as possible the response to the antibiotic therapy. Is therefore necessary to find real time biological markers that will help to understand the clinical situation of the infected patient. It has been demonstrated that fibronectin (Fn) is an early marker of sepsis, so it seemed plausible its use in the clinical monitoring of the septic patient. MATERIAL: We have used plasmatic concentrations of Fn in the follow up of sepic patients admitted to the Hospital de Segovia from February to August, 1995. There were two control groups: one of healthy volunteers and another of varied pathology. RESULTS: We have applied the multiple comparison rule of Bonferroni to demonstrate that plasma Fn is a negative acute phase reactant, with almost undetectable levels while the patient is in critical condition. An effective treatment prompts plasma Fn to rise significantly within two days. DISCUSSION: Plasma Fn concentration by itself or in an score system could help in the follow up of the septic patients.

Acute-Phase Reaction↗

PubMed2001

Respiratory sinus arrhythmia from two coupled pacemakers.

We reproduce global features of respiratory sinus arrhythmia (RSA), a prominent source of heart rate variability, from two signals coupled in alternate fashion so dominance periodically switches back and forth between them. We consider two different possibilities for this coupling and illustrate our method with numerical simulations that we contrast with the corresponding results from real data. We interpret our findings within the context of the two-pacemaker model of the heartbeat, an alternative to the single-pacemaker mechanism of pulse generation in the orthodox conduction model.

Arrhythmias, Cardiac↗