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Biomedical subjects

A Rodríguez

Publications and source records attributed to A Rodríguez.

At least 37 records · Page 2Linked to original sources
PubMed2006

HOMA, QUICKI and MFfm to measure insulin resistance in morbid obesity.

BACKGROUND: The relationship between morbid obesity (MO) and insulin resistance (IR) has been widely demonstrated. The euglycemic-hyperglycemic clamp method for diagnosis of IR is neither practical nor cost-effective for population-based studies. However, the application of mathematical models (HOMA, QUICKI and Mf(fm) indices) can be useful. METHODS: The data from 171 patients were retrospectively evaluated. We recorded general anthropometric parameters and the basal levels of glucose, triglycerides and insulin and calculated the metabolic indexes both before surgery (Capella gastric bypass) and 6, 12, 24, 36 and 48 months after the operation. RESULTS: Before surgery, patients could be classified according to their waist-hip ratio (WHR) into 2 groups. Group A (n = 131, 108 females and 23 males) with WHR values 1.10 +/- 0.1 SD for males and 0.94 +/- 0.1 for females (central obesity); and Group B (n = 40, 34 females and 6 males) with WHR values 0.90 +/- 0.1 for males and 0.84 +/- 0.1 for females (peripheral obesity). Group A patients showed elevated serum levels of glucose, triglycerides and insulin and high values of the HOMA index with low values of QUICKI and Mf(fm). Group B patients showed lower levels of glucose, triglycerides, insulin and HOMA index and higher values of QUICKI and Mf(fm). These abnormal levels began to decrease 6 months after bypass and the QUICKI and Mf(fm) began to increase. CONCLUSIONS: The high baseline levels of insulin and the high prevalence of hypertension, diabetes or both conditions in patients with central obesity confirm that they suffer a metabolic syndrome, Meanwhile, patients with peripheral obesity with lower levels of chemical parameters and of the metabolic indices suffer peripheral resistance against insulin. Clinical application of these mathematical indices can be useful in patients with MO; they are easily performed and lack the high costs and risks associated with the clamp technique.

Adolescent↗
PubMed2006

[Acute rejection of kidney transplant is associated with induction of replicative senescence in CD8+ T lymphocytes].

Acute renal rejection repeatedly activates immunocompromised CD8 + T cells. Maintained activation of CD8 + T cells can induce a process of replicative senescence. In the present study, we will evaluate in CD8 lymphocytes from patients undergoing acute renal rejection characteristics of replicative senescence such as: a) low expression of CD28 molecule; b) telomere shortening and c) increase production of proinflammatory cytokines. The study was carried out in CD8 + T cells from 14 patients transplanted without clinical evidences of acute renal rejection, 14 patients kidney transplanted with clinical and anatomopathological evidences of acute renal rejection, 8 healthy controls. The results shown that in peripheral blood and renal biopsy of patients with acute renal rejection there is a significant increment of the population of T cells CD28-CD8+, with short telomere length, as compared with healthy controls and patients without acute renal rejection. The presence of senescent cells was associated with high levels of IL-10 and IFN-Y in plasma and urine. In conclusion our study suggest that the CD8 + T cells of patients with acute renal rejection suffer a process of replicative senescence.

Adult↗
PubMed2006

[Anesthetic management for left ventricular epicardial lead implantation with minimally invasive thoracoscopic guidance].

Medical treatment for left ventricular (LV) systolic dysfunction and congestive heart failure has improved quality of life for patients but mortality rates have remained unaffected. For a subgroup of such patients with interventricular conduction delays and ventricular contraction dyssynchrony, cardiac resynchronization by placement of a LV epicardial lead is a new approach to management. We report 3 cases in which such electrodes were implanted under the guidance of minimally invasive thoracoscopy. In the first 2 cases it was decided to place the LV electrode using thoracoscopic guidance because of complications or technical difficulties in the percutaneous procedure. In the third case thoracoscopy was used because of deterioration of the patient's condition after implantation of a double-chamber pacemaker and shifting of the lead to the right ventricle. The literature on the anesthetic management of such patients is scarce. Although sedation with general anesthesia and single-lung ventilation is indicated for percutaneous procedures, that technique also proved adequate for the thoracoscopic procedures.

Aged↗
PubMed2006

[Heparin-induced thrombocytopenia in hemodialysis. Case report and review of the literature].

Thrombocytopenia is a potential complication of heparin therapy. There are two forms of heparin-induced thrombocytopenia (HIT). Type-I HIT is characterized by a mild decrease in platelet count that occurs within the first 2-4 days after heparin initiation. The platelet count often returns to normal without stop heparin treatment. The mechanism of thrombocytopenia appears to be due to a direct effect of heparin on platelet activation. The second form (type-II) is an immune-mediated disorder characterized by severe thrombocytopenia, which may include both arterial and venous thrombosis. We present a case of type-II HIT occurred in a hemodialysis patient resulting in acute pulmonary embolism and peripheral venous thrombosis, and review the literature.

Algorithms↗
PubMed2005

Oxidation, glycoxidation, lipoxidation, nitration, and responses to oxidative stress in the cerebral cortex in Creutzfeldt-Jakob disease.

Gel electrophoresis and Western blotting of frontal cortex homogenates have been carried out in sporadic Creutzfeldt-Jakob disease (CJD) cases and age-matched controls to gain understanding of the expression of glycation-end products (AGEs). N-Carboxymethyl-lysine (CML) and N-carboxyethyl-lysine (CEL) were used as markers of glycoxidation; 4-hydroxynonenal (4-HNE) and malondialdehyde-lysine (MDAL) as markers of lipoxidation; and nitrotyrosine (N-tyr) and neuronal, endothelial and inducible nitric oxide synthase (nNOS, eNos and iNos) as markers of protein nitration and as sources of NO production, respectively. Age receptor (RAGE) and Cu/Zn superoxide dismutase (SOD1) and Mn superoxide dismutase (SOD2) expression levels were also examined. The results showed a significant increase in the expression levels of AGE (p<0.05), CEL (p<0.001), RAGE (p<0.05), HNE-modified proteins (p<0.01), nNOS, iNOS and eNOS (p<0.01 and p<0.05, respectively), N-tyr (p<0.05), and SOD1 (p<0.05) and SOD2 (p<0.05). No relationship was observed between PrP genotype, PrP type, PrP burden, and expression levels of oxidative stress markers. The present findings demonstrate oxidative, glycoxidative, lipoxidative and nitrative protein damage, accompanied by increased oxidative responses, in the cerebral cortex in sporadic CJD. These results provide support for the concept that oxidative stress may have important implications in the pathogenesis of prion diseases.

Aged↗
PubMed2005

Antibiotic prescription for community-acquired pneumonia in the intensive care unit: impact of adherence to Infectious Diseases Society of America guidelines on survival.

BACKGROUND: The purpose of our study was to analyze prognostic factors associated with mortality for patients with severe community-acquired pneumonia (CAP). METHODS: We conducted a prospective multicenter study including all patients with CAP admitted to the intensive care unit during a 15-month period in 33 Spanish hospitals. Admission data and data on the evolution of the disease were recorded. Multivariate analysis was performed using the SPSS statistical package (SPSS). RESULTS: A total of 529 patients with severe CAP were enrolled; the mean age (+/-SD) was 59.9+/-16.1 years, and the mean Acute Physiology and Chronic Health Evaluation (APACHE) II score (+/-SD) was 18.9+/-7.4. Overall mortality among patients in the intensive case unit was 27.9% (148 patients). The rate of adherence to Infectious Diseases Society of America (IDSA) guidelines was 57.8%. Significantly higher mortality was documented among patients with nonadherence to treatment (33.2% vs. 24.2%). Multivariate analysis identified age (odds ratio [OR], 1.7), APACHE II score (OR, 4.1), nonadherence to IDSA guidelines (OR, 1.6), and immunocompromise (OR, 1.9) as the variables present at admission to the intensive care unit that were independently associated with death in the intensive care unit. In 15 (75%) of 20 cases of Pseudomonas aeruginosa infection, the antimicrobial treatment at admission was inadequate (including 8 of 15 cases involving patients with adherence to IDSA guidelines). Chronic obstructive pulmonary disease (OR, 17.9), malignancy (OR, 11.0), previous antibiotic exposure (OR, 6.2), and radiographic findings demonstrating rapid spread of disease (OR, 3.9) were associated with P. aeruginosa pneumonia. CONCLUSIONS: Better adherence to IDSA guidelines would help to improve survival among patients with severe CAP. Pseudomonas coverage should be considered for patients with chronic obstructive pulmonary disease, malignancy, or recent antibiotic exposure.

Anti-Bacterial Agents↗
PubMed2005

Metabotropic glutamate receptor/phospholipase C pathway: a vulnerable target to Creutzfeldt-Jakob disease in the cerebral cortex.

Glutamate is the main excitatory neurotransmitter in the cerebral cortex. Altered glutamatergic transmission has been suggested as having a central role in many neurodegenerative diseases. Metabotropic glutamate receptors (mGluRs) are coupled to intracellular signal transduction via G proteins, and they mediate slower responses than ionotropic glutamate receptors. Group I mGluRs are positively coupled to phospholipase C beta1 (PLCbeta1). Creutzfeldt-Jakob disease (CJD) is a human transmissible spongiform encephalopathy associated with a dysfunction in the membrane glycoprotein PrP which is converted into an abnormal isoform, with a predominant beta-sheet structure, that is pathogenic and partially resistant to protease digestion. Proteins associated with the signal transduction of group I mGluRs were examined in the frontal cortex (area 8) of 12 cases with sCJD and four age-matched controls, by means of gel electrophoresis and Western blotting of total homogenates. Densitometric analysis of the bands demonstrated decreased expression levels of PLCbeta1 and PLCgamma, a non-related phospholipase which is a substrate of tyrosine kinase, in CJD cases when compared with controls. Novel protein kinase C delta (nPKCdelta) has also been found to be significantly decreased in CJD cases. However, no modifications in mGluR1 cPKCalpha expression levels are found in CJD when compared with controls. No modifications in PLCbeta1 solubility in PBS-, deoxycholate- and sodium dodecylsulphate-soluble fractions have been observed in CJD when compared with controls. Finally, no interactions between PLCbeta1 and PrP, as revealed by immunoprecipitation assays, have been found in CJD and controls. The present results show, for the first time, reduced expression levels of phospholipases, particularly PLCbeta1, which may interfere with group I mGluR signaling in the cerebral cortex in CJD. These abnormalities are not the result of abnormal PLC solubility or interactions with PrP. Selective involvement of group I mGluRs may have functional effects on glutamatergic transmission modulation and processing in CJD.

Adult↗
PubMed2005

Organogenic responses of Pinus pinea cotyledons to hormonal treatments: BA metabolism and cytokinin content.

Isolated cotyledons from mature Pinus pinea L. embryos were cultured in vitro in a factorial combination of 4.4, 10 and 44.4 microM N6-benzyladenine (BA) for 2, 4, 8, 16 and 35 days to optimize shoot regeneration. Incubation of explants in 44.4 microM BA for 4 days, in place of the standard incubation in 4.4 microM BA for 35 days, reduced the entire culture period to 4 weeks. Shortening the culture period had no significant effect on the caulogenic response or the number of buds formed per cotyledon. To establish the relationship between key moments in the caulogenic process induced by 4.4 microM BA and the endogenous concentrations of the active forms of BA and other isoprenoid-type cytokinins (CKs), we examined uptake, metabolism and amount of BA, as well as the amounts of zeatin, dihydrozeatin and their ribosides in P. pinea cotyledons after 1, 2, 6, 12 and 24 h, and 2, 4, 8, 16 and 35 days of exposure to 8-[14C]BA. Uptake and release of BA were associated with water movement between explants and the medium during the first 8 days of culture. The interconvertible forms of BA were the main metabolites formed in the tissues. Inactivation of BA as a result of conjugation or oxidation was insignificant. The endogenous concentration of BA + N6-benzyladenosine was 20-fold higher than the exogenously applied BA during the competence acquisition phase (Days 0-3). The concentration of isoprenoid-type CKs also increased 16-fold and then decreased during this time. Induction of shoot buds (Days 4-8) was characterized by a second peak of BA uptake by explants that triggered the synthesis of N6-benzyladenosine-5 -monophosphate and by the maintenance of isoprenoid-type CKs. Reestablishment of CK homeostasis marked the shift from the induction phase to the shoot development phase in this organogenic process (Days 8-12).

Benzyl Compounds↗
PubMed2005

Intraoperative recording of electroneurographic signals from cuff electrodes on extradural sacral roots in spinal cord injured patients.

PURPOSE: A safe and reliable method for monitoring intravesical pressure on a long-term basis is needed for conditional electrical stimulation to be feasible as a treatment option for neurogenic detrusor overactivity in patients with a spinal cord injury. Therefore, we investigated the possibility of recording afferent nerve activity related to mechanical activity of the bladder and other pelvic organs from the extradural sacral nerve root in human. MATERIALS AND METHODS: Nerve cuff electrodes were temporary placed on the extradural S3 sacral root in 6 spinal cord injured patients who underwent implantation of an extradural FineTech-Brindley Bladder System (Finetech Medical Lt., Welwyn Garden City, United Kingdom). The dorsal penile/clitoral nerve was electrically stimulated to evoke compound action potentials. Electroneurographic signals were recorded together with bladder and rectal pressure during mechanical stimulation of the dermatome rapid bladder filling and rectal distention, and during bladder contraction evoked by electrical stimulation of the contralateral sacral root. RESULTS: Compound action potentials and electroneurographic responses during stimulation of the dermatome and rectum were present in all 6 patients and during bladder filling in 5 of 6. However, recorded responses from the bladder and rectum were small and mainly phasic in nature. Nerve responses following bladder contractions were present in 4 of 5 stimulated patients. CONCLUSIONS: Afferent nerve activity from the dermatome, bladder and rectum can be recorded using cuff electrodes placed on the extradural S3 sacral root in humans but improvements in recording quality and sophisticated signal processing methods are needed for chronic application.

Action Potentials↗
PubMed2005

Advances in the management of pneumonia in the intensive care unit: review of current thinking.

Interventions to prevent pneumonia in the intensive care unit should combine multiple measures targeting the invasive devices, microorganisms and protection of the patient. Microbiological investigation is useful for evaluating the quality of the respiratory sample, and permits early modification of the regimen in light of the microbiological findings. Once pneumonia develops, the appropriateness of the initial antibiotic regimen is a vital determinant of outcome. Three questions should be formulated: (1) is the patient at risk of acquiring methicillin-resistant Staphylococcus aureus, (2) is Acinetobacter baumannii a problem in the institution, and (3) is the patient at risk of acquiring Pseudomonas aeruginosa? Antibiotic therapy should be started immediately and must circumvent any pathogen resistance mechanisms developed after previous antibiotic exposure. Therefore, antibiotic choice should be institution-specific and patient-oriented.

Acinetobacter Infections↗
PubMed2005

Morbid obesity, hypertensive disease and the renin-angiotensin-aldosterone axis.

BACKGROUND: Resistance to insulin and secondary hyperinsulinemia seem to be the putative link between morbid obesity (MO) and hypertensive disease (HD). Adipose tissue can secrete leptin and angiotensinogen, among other substances. Leptin activates the sympathetic nervous system, leading to HD. Angiotensinogen is a substrate for renin, therefore taking part in the renin-angiotensin-aldosterone axis and the regulation of blood pressure. In MO, both hypertrophy and hyperplasia of the adipocytes lead to an increase in the secretion of both substances, leading to loss of the equilibrium between the levels of both hormones. The aim of the present study was to evaluate these abnormalities and their potential reversibility following bariatric surgery. METHODS: Data from 100 patients with MO was retrospectively evaluated. Anthropometric data, the plasma renin activity (PRA), plasma levels of aldosterone, ACE, potassium and sodium were collected both prior to surgery and 6, 12, 24 and 36 months after surgery. RESULTS: The waist-hip ratio (WHR) before surgery allowed classification of our patients in two groups: central obesity (WHR > or =0.90 in men and > or =0.85 in women); peripheral obesity (WHR <0.90 in men and <0.85 in women). In patients with central obesity, high levels of PRA, aldosterone and ACE with sodium retention and potassium loss and high insulin levels, were found. These changes were not found in patients with peripheral obesity. After gastric bypass, these abnormalities tended to disappear, mainly in the first 6 months. CONCLUSIONS: The reduction of BMI and WHR after gastric bypass confirmed this operation to be effective against MO. The high basal levels of insulin and the high rate of HD and diabetes in patients with central obesity seem to indicate that they suffer a metabolic syndrome with significant hormonal imbalances and sodium retention. Patients with peripheral obesity only showed a peripheral resistance against insulin, probably with a shorter duration of the hormonal action, but they did not show hormonal abnormalities or sodium retention. After gastric bypass these abnormal hormone levels tended to normalize.

Adolescent↗
PubMed2005

Oocytes recovered from cows treated with retinol become unviable as blastocysts produced in vitro.

Retinoids have been shown to enhance developmental competence of the oocyte in cattle, sheep and pigs. In this study we investigated whether exogenous retinol stimulates the bovine oocyte during its intrafollicular growth and the time limits of exposure to exogenous retinol. In addition, we also determined the efficiency of ovum pick-up techniques in combination with retinol treatment and the viability of embryos after transfer to recipients. In Experiment 1, heifers were injected with retinol or vehicle, and concentrations of retinol in the blood were analysed on Day 0 (prior to injection), Day 1 and, together with follicular fluid, Day 4. Blood retinol increased by Day 1 and cleared on Day 4, but retinol remained higher within the follicle. In Experiment 2, oocyte donors were injected weekly with retinol or vehicle four times during a twice-per-week cycle of eight recovery sessions (starting 4 days before the first session), followed by a second eight-session cycle without treatment. Oocytes recovered were fertilized and cultured in vitro. Retinol treatment yielded higher numbers of low-quality oocytes throughout, although retinol measured during cycles did not change. Total oocytes, and morulae and blastocyst rates, increased during the first five sessions following treatment with retinol. As previously shown with oocytes from slaughterhouse ovaries, retinoic acid stimulated blastocyst development. Following transfer to recipients, blastocysts from oocytes exposed to retinol were unable to establish pregnancy. Our study confirms the existence of an effect of retinol on the intrafollicular oocyte in the cow and provides evidence regarding the teratogenic effect of retinol.

Animals↗
PubMed2004

Optimization of pulping conditions of abaca. An alternative raw material for producing cellulose pulp.

The influence of temperature (150-170 degrees C), pulping time (15-45 min) and soda concentration (5-10%) in the pulping of abaca on the yield, kappa, viscosity, breaking length, stretch and tear index of pulp and paper sheets, was studied. Using a factorial design to identify the optimum operating conditions, equations relating the dependent variables to the operational variables of the pulping process were derived that reproduced the former with errors lower than 25%. Using a high temperature, and a medium time and soda concentration, led to pulp that was difficult to bleach (kappa 28.34) but provided acceptable strength-related properties (breaking length 4728 m; stretch 4.76%; tear index 18.25 mN m2/g), with good yield (77.33%) and potential savings on capital equipment costs. Obtaining pulp amenable to bleaching would entail using more drastic conditions than those employed in this work.

Bioreactors↗
PubMed2004

Commissioning of a medical accelerator photon beam Monte Carlo simulation using wide-field profiles.

A method for commissioning an EGSnrc Monte Carlo simulation of medical linac photon beams through wide-field lateral profiles at moderate depth in a water phantom is presented. Although depth-dose profiles are commonly used for nominal energy determination, our study shows that they are quite insensitive to energy changes below 0.3 MeV (0.6 MeV) for a 6 MV (15 MV) photon beam. Also, the depth-dose profile dependence on beam radius adds an additional uncertainty in their use for tuning nominal energy. Simulated 40 cm x 40 cm lateral profiles at 5 cm depth in a water phantom show greater sensitivity to both nominal energy and radius. Beam parameters could be determined by comparing only these curves with measured data.

Algorithms↗
PubMed2004

Clusterin solubility and aggregation in Creutzfeldt-Jakob disease.

Prion protein (PrPC) is a glycolipid-anchored cell membrane syaloglycoprotein that localizes in presynaptic membranes. PrP has the property of aggregating into amyloid fibrils and being deposited in the brains in cases with transmissible encephalopathies (TSEs), when PrPC is converted into abnormal protease-resistant PrP (PrPRES). Clusterin is a heterodimeric glycoprotein, the expression of which is enhanced in astrocytes in association with punctate-type PrPRES deposits during TSE progression. In addition, clusterin co-localizes in PrPRES plaques in several human TSEs, including Creutzfeldt-Jakob disease (CJD). Clusterin is up-regulated in the cerebral cortex and cerebellum in CJD as revealed by DNA micro-array technology. Clusterin expression was examined in seven sporadic cases of CJD (codon 129 genotype, PrP type: 4 MM1, 1 MV1, 1 MV2, 1 VV2) and three age-matched controls by immunohistochemistry, Western blotting and solubility. In addition to small punctate clusterin deposition in the neuropil, single- and double-labeling immunohistochemistry disclosed clusterin localization in PrPRES plaques, which predominated in the cerebellum of cases MV1, MV2 and VV2. Moreover, clusterin in plaques, but not punctate clusterin deposits, was resistant to protease digestion, as revealed in tissue sections pre-incubated with proteinase K. Clusterin in CJD, but not clusterin in control brains, was partially resistant to protease digestion in Western blots of total brain homogenates immunostained with anti-clusterin antibodies, which were processed in parallel with Western blots to PrP, without and with pre-incubation with proteinase K. Protein aggregation was analyzed in brain homogenates subjected to several solvents. PrP was recovered in the deoxycholate fraction in control and CJD cases, but in the SDS fraction only in CJD, thus indicating differences in PrP solubility between CJD and controls. Clusterin was recovered in the cytosolic, deoxycholate and SDS fraction in both CJD and control cases, but only clusterin from CJD was recovered in the urea-soluble fraction and, especially, in the remaining pellet. These findings demonstrate the capacity of clusterin to form aggregates and interact with PrPRES aggregates. The implications of this property are not known, but it can be suggested that clusterin participates in PrP clustering and sequestration, thus modifying PrP toxicity in CJD.

Aged↗