Search PubMed⌕ Search

Biomedical subjects

A Díez

Publications and source records attributed to A Díez.

At least 19 recordsLinked to original sources
PubMed2006

Thermodynamic properties of van der Waals fluids from Monte Carlo simulations and perturbative Monte Carlo theory.

Computer simulations have been performed for fluids with van der Waals potential, that is, hard spheres with attractive inverse power tails, to determine the equation of state and the excess energy. On the other hand, the first- and second-order perturbative contributions to the energy and the zero- and first-order perturbative contributions to the compressibility factor have been determined too from Monte Carlo simulations performed on the reference hard-sphere system. The aim was to test the reliability of this "exact" perturbation theory. It has been found that the results obtained from the Monte Carlo perturbation theory for these two thermodynamic properties agree well with the direct Monte Carlo simulations. Moreover, it has been found that results from the Barker-Henderson [J. Chem. Phys. 47, 2856 (1967)] perturbation theory are in good agreement with those from the exact perturbation theory.

Journal Article↗
PubMed2002

Restoration of peristalsis in the esophagus of a patient diagnosed of achalasia.

We report the case of a patient with dysphagia in whom a clinical and manometric follow-up was carried out. We initially observed a motor disorder of the esophageal spasm type. During manometric follow-up a progression to vigorous achalasia was observed. The patient was treated with pneumatic dilation, which obtained a good response to treatment. In manometries performed after treatment we observed a return of peristalsis in the distal esophageal body. Early treatment and short evolution of disease may allow peristalsis to recover in these cases. Peristalsis recovery casts new doubts on achalasia etiology.

Adult↗
PubMed2001

Osteoblasts in HIV-infected patients: HIV-1 infection and cell function.

BACKGROUND: HIV-infected patients have been shown to have a severe alteration in osteoblast function that appears to be related to the infection. OBJECTIVE: To determine whether normal human osteoblasts express CD4, whether osteoblasts from patients with HIV infection are infected by HIV-1 and whether osteoblast dysfunction observed in vivo also occurs in vitro. METHODS: Osteoblast cultures from bone marrow biopsies of HIV-infected patients (n = 14) and control patients (n = 10) were used in a cross-sectional study and a case-control prospective study. Expression of CD4 was analysed using flow cytometry and reverse transcriptase polymerase chain reaction; the presence of HIV-1 particles was determined by measuring p24 antigen in the supernatants of osteoblast cultures and viral DNA or RNA in the osteoblasts using the polymerase chain reaction. Osteoblast function was assessed by measuring cell proliferation, type I collagen and osteocalcin synthesis. RESULTS: In human osteoblasts, CD4 expression could not be determined using flow cytometry, although low levels of mRNA coding for CD4 were detected. HIV infection was not observed in osteoblast cultures from HIV-infected patients nor was there any alteration in replication and synthesis of type I collagen, although osteocalcin synthesis was increased. CONCLUSIONS: It is unlikely that HIV-1 infects human osteoblasts in vivo; therefore, the hypothesis that these cells could act as local HIV-1 reservoirs should be reconsidered.

Adult↗
PubMed2001

Virologic outcome and predictors of virologic failure of highly active antiretroviral therapy containing protease inhibitors.

In this observational single-center cohort study outside the clinical trial setting, outcome and predictors of virologic failure of highly active antiretroviral therapy (HAART) containing a protease inhibitor were evaluated in human immunodeficiency (HIV)-infected persons. The study population consisted of 807 protease inhibitor-naive HIV-seropositive patients who initiated antiretroviral therapy with reverse transcriptase inhibitors and protease inhibitors (indinavir, nelfinavir, ritonavir) between January 1997 and January 1999. Demographic variable, plasma HIV-1 RNA levels, CD4+ T-cell count, adverse drug reactions, and adherence to HAART were assessed. Virologic treatment response was defined as a decrease in plasma HIV-1 RNA load from baseline to below 500 copies per milliliter after 12 months of therapy. Levels of HIV-1 RNA were undetectable in 43% of patients at 12 months. Factors associated with failure to suppress viral load included age 40 years or younger, baseline CD4+ T cell count less than 200 x 10(6) per liter baseline viral load greater than 4.3 log(10) per milliliter, and non-adherence to HAART. After adjustment by logistic regression, non-adherence was the only statistically significant variable associated with virologic failure (odds ratio 0.38, 95% confidence interval 0.21 to 0.67). Unselected patients in whom protease inhibitor is started in a usual clinical setting achieve viral suppression less frequently than do patients in controlled clinical trials. Failure to adherence to HAART was the strongest predictor of virologic failure.

Adult↗
PubMed2001

Subjective quality of life in schizophrenic outpatients in a Catalan urban site.

The aim of this cross-sectional study was to assess the subjective quality of life of chronic schizophrenic outpatients living in an urban site in Catalonia (Spain) during a stable phase of the illness. We included 44 patients with a DSM-IV diagnosis of psychotic disorder. Sociodemographic, clinical, and treatment variables were obtained and compared with the subjective quality of life as assessed by the Lehman Quality of Life Interview-short version. The descriptive analysis of the subjective quality of life profile obtained in our sample shows moderate levels of satisfaction in most subscales. Results regarding comparisons showed that sociodemographic, clinical, premorbid adjustment and treatment variables were only related to subjective quality of life in particular life domains and in a nonconclusive way. The need to include other relevant variables such as insight or psychological traits in the study of the quality of life phenomenon in schizophrenia is highlighted.

Adult↗
PubMed2001

Sedation for gastrointestinal endoscopy. Analysis of tolerance and complications.

OBJECTIVE: To analyse tolerance and complications in patients undergoing a gastrointestinal endoscopy. PATIENTS AND METHODS: One hundred forty three patients were prospectively studied: 44.8% underwent a diagnostic upper endoscopy; 13.3%, a therapeutic upper endoscopy; 37%, a diagnostic colonoscopy and 4.9%, a therapeutic colonoscopy. Midazolam or midazolam combined with meperidine were used. Tolerance, level of sedation and complications were studied. Chis quare and ratio comparison tests were used for the statistical analysis. P-values less than 0.05 were considered as statistically significant. RESULTS: In the diagnostic upper endoscopy group, tolerance was better with midazolam plus meperidine vs midazolam only (83.8% and 59.3% respectively); p < 0.05. In the therapeutic upper endoscopy group, tolerance was also better when both drugs were combined; p < 0.05. In the diagnostic and therapeutic colonoscopy groups, tolerance was good in 63.5% and 85.7% of patients, respectively. Men had better tolerance for upper endoscopy; p < 0.05. Tolerance was worse in patients under 40 years of age for upper endoscopy; p < 0.05. Mild desaturation occur in 27.3% of patients, being more severe in therapeutic procedures; p < 0.05. CONCLUSIONS: Tolerance was good in a high percentage of patients, and better in men and in patients older than 40 years of age. The main problem is desaturation, that increases in therapeutic procedures.

Adolescent↗
PubMed2000

[Treatment of osteoporosis with calcium and vitamin D. Systematic review].

BACKGROUND: Systematic review of the efficacy of calcium and vitamin D for the treatment of osteoporosis. MATERIAL AND METHOD: Review of the database MEDLINE between 1996 and may 1998, by the key words: osteoporosis, calcium, vitamin D (and related terms) and randomized clinical trial. Review of the electronic versions of Best Evidence, The Cochrane Library, congress abstracts and references from two main textbooks. Ascending review of the literature. All the reviews were performed independently by two of the authors. Design parameters and main results of the primary publications of the identified trials were tabulated. Two independent observers carried out methodological scoring of the studies. Results were tabulated and a judgement made for the results. RESULTS: Eleven studies on calcium, 8 of vitamin D and 12 about calcitriol and other hormone derivatives were included. Studies with calcium were mainly performed on non-clinical populations and in three anti-fracture efficacy was analyzed. Results were positive in population with low baseline intake and substantial supplementation. Trials on vitamin D were done in non-clinical and on institutionalized populations. Trials with calcitriol were developed mainly in osteoporotic fracture populations and reached poorer methodological validity scores. Heterogeneity of the studies precluded a meta-analysis of the different treatments. Studies on calcium showed clinical efficacy in a more consistent way. Inter-observer score was good (kappa = 0.81) and there were no significant correlations between sample size and effect in the different studies. CONCLUSIONS: Calcium treatment is efficacious in populations with low intake receiving substantial supplementation. Vitamin D is efficacious associated with calcium mainly in deficient populations. Efficacy of calcitriol and other derivatives is more controversial.

Calcitriol↗
PubMed2000

Inhibition of cellular proliferation by drug targeting of cyclin-dependent kinases.

Abnormal cellular proliferation is associated with the pathology of several diseases, including cancer, atherosclerosis and restenosis post-angioplasty. Therefore, antiproliferative therapies may be a suitable approach to treat these disorders. Candidate targets for such strategies include specific components of the cell cycle machinery. Progression through the cell cycle in mammalian cells requires the activation of several cyclin-dependent protein kinases (CDKs) through their association with regulatory subunits called cyclins. Active CDK/cyclin holoenzymes phosphorylate cellular proteins including the retinoblastoma susceptibility gene product (pRb) and the related pocket proteins p107 and p130. Several compounds have been described that directly or indirectly inhibit the activity of CDKs, which results in a suppression of cell growth. In this review, we will discuss the use of drugs targeting CDKs and their therapeutic application in animal models and clinical trials.

Animals↗
PubMed2000

Short-term modulation of lipogenesis by macronutrients in rainbow trout (Oncorhynchus mykiss) hepatocytes.

Rainbow trout (Oncorhynchus mykiss) hepatocytes were cultured under simulated conditions of varying nutritional status to explore the short-term modulation by dietary substrates of the main lipogenic enzymes: glucose-6-phosphate dehydrogenase (G6PD), malic enzyme (ME), ATP-citrate lyase (ACL), acetyl-CoA carboxylase (ACoAC) and fatty acid synthetase (FAS). Primary cultures were individually exposed to varying amounts of glucose, hydrolysed casein and long-chain polyunsaturated fatty acids (PUFA) for 12 h. A second set of experiments was designed to evaluate the effects of mixing different relative amounts of these macronutrients in the culture medium. Glucose concentrations of up to 20-25 mm showed a stimulatory effect on G6PD, ME, ACL and ACoAC activity while an earlier inhibitory effect on FAS was observed at 10-20 mm glucose The use of hydrolysed casein as a nutritional source of amino acids inhibited the activity of FAS and ME and stimulated G6PD, ACoAC and ACL activity Low levels of linolenic acid exerted a stimulatory effect on all the lipogenic enzymes assayed with the exception of FAS, and increased amounts showed some inhibition of lipogenic activities Eicosapentaenoic acid and docosahexaenoic acid showed a similar effect, although the former strongly inhibited FAS activity while the latter showed greater potential to inhibit ACoAC and G6PD. A complete change in the relative levels of glucose, hydrolysed casein and PUFA in turn led to changes in the enzyme activity patterns observed. The present study shows the feasibility of exploring the direct regulation of lipogenesis in isolated fish cells by varying the relative amounts of main macronutrients, mimicking in vivo dietary conditions. It is felt that such an approach may serve to investigate the macronutrient regulation of other metabolic pathways.

Animals↗
PubMed1999

In vitro synthesis of type I collagen: quantification of carboxyterminal propeptide of procollagen type I versus tritiated proline incorporation.

Radioimmunoassay of the carboxyterminal propeptide of human type I procollagen has been recently introduced to measure in vitro synthesis of type I collagen by osteoblasts and fibroblasts. However, it has not been assessed whether the equivalent results are obtained with this new assay and with tritiated proline incorporation to collagen protein. To this purpose, both methods were used to quantify synthesis of type I collagen in normal human osteoblast cultures to which fetal calf serum and human serum were added in order to stimulate protein synthesis. A positive correlation in the results obtained by both methods was obtained (r = 0.95, P = 0.0001). Given the technical advantages of detection of levels to carboxyterminal propeptide of type I procollagen, we consider that this is the technique of choice for the quantification of in vitro synthesis of type I collagen by normal human osteoblasts.

Aged↗
PubMed1999

[Adherence to very active antiretroviral treatment: impact of individualized assessment].

BACKGROUND: To determine if the intervention of individual advice improves adherence and effectiveness to highly active antiretroviral therapy. METHODS: Randomized open trial. Patients treated with zidovudine + lamivudine + indinavir were assigned (2/1) to conventional care or individual advise. Individual advise consists in adaptation to treatment to patient style of live and detailed information of therapy. Adherence were estimated with structured interview and pillo counts and were considered correct when more than 90% of prescribed drugs were taken. RESULTS: Patients 170, conventional care: 110 and IA: 60. FOLLOW-UP: 24 weeks. Baseline characteristics were similar in both groups. Correct adherence were estimated in 52.7% of conventional care and in 76.7% of individual advise (p = 0.002, relative risk: 1.45; CI 95%: 1.16-1.82). Undetectable viral load (NASBA < 50 copies/ml) in 54.5% of conventional care and in 65% of individual advise (p = 0.18, relative risk: 1.19; CI 95%: 0.93-1.53). Reduction of viral load in the conventional care group 1.02 +/- 0.5 log10/ml, and in the individual advise group 1.98 +/- 0.7 log10/ml. CONCLUSION: The individual advice improve adherence with a tendency to improve effectiveness of highly active antiretroviral therapy.

Adult↗
PubMed1999

DNA image cytometry. An alternative method in osteoblast proliferation assays.

OBJECTIVE: To assess whether DNA image cytometry can be used as an alternative method to tritiated thymidine uptake quantification in osteoblast proliferation assays. STUD DESIGN: Proliferation of normal human osteoblasts incubated with normal human serum at 0%, 2.5%, 5%, 10%, 20% and 40% was quantified by tritiated thymidine uptake quantification and DNA image cytometry. RESULTS: Tritiated thymidine uptake quantification showed that normal human serum stimulated the proliferation of normal human osteoblasts and that the degree of stimulation was directly related to the concentration of serum in the culture medium. Similar results were obtained when the DNA image cytometry assay was used. A highly significant linear relationship between the ranks of both methods was found (Spearman's r = 1.00, P = .0253). CONCLUSION: DNA image cytometry may be a valuable alternative when the use of radioactive material is not desired and/or subsequent morphologic or immunocytochemical characterization of cells under study is required.

Aged↗