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Biomedical subjects

R Salazar

Publications and source records attributed to R Salazar.

At least 19 recordsLinked to original sources
PubMed2004

Spectrophotometric and electrochemical study of the inclusion complex between beta-cyclodextrin and furnidipine.

Inclusion complexation between furnidipine (2,6-dimethyl-4-(2-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-tetrahydrofurfuryl 5-methyl diester), a calcium-channel antagonist, and beta-cyclodextrin (beta-CyD) was studied in aqueous solution by using both spectrophotometric and electrochemical measurements. The phase solubility profile was classified as A(L)-type, indicating the formation of 1:1 stoichiometric inclusion complex of furnidipine with beta-CyD. Based on the spectrophotometric absorbance's variations, a formation constant value, K(f), of 156 M(-1) was determined. Electrochemical measurements using chronocoulometric experiments were used for the determination of the diffusion coefficients. In absence of beta-CyD, a diffusion coefficient value of 4.32 x 10(-6) cm2 s(-1) was obtained for furnidipine. The addition of beta-CyD produced a decrease of 30% for the diffusion coefficient. Formation of inclusion complexes of furnidipine with beta-CyD was proved to increase more than three times the solubility of furnidipine.

Calcium Channel Blockers↗
PubMed2004

Synchronization of surface reactions via Turing-like structures.

We discuss an alternative to the traditional gas-phase coupling approach in order to explain synchronized global oscillations in CO oxidation on Pt(110). We use a microscopic model which includes structural Pt surface reconstruction via front propagation, and large diffusion rates for CO. The synchronization mechanism is associated with the formation of a Turing-like structure of the substrate. By using large parallel microscopic simulations we derive scaling laws which allow us to extrapolate to realistic diffusion rates, pattern size, and oscillation periods.

Journal Article↗
PubMed2003

Conventional cutting vs. internal anal sphincter-preserving seton for high trans-sphincteric fistula: a prospective randomized manometric and clinical trial.

BACKGROUND: Cutting setons have been used in complicated perirectal sepsis with good effect, although there is a moderately high incidence of fecal leakage after their use. The aim of this study was to compare a modified cutting seton, which repaired the internal anal sphincter muscle and re-routed the seton through the intersphincteric space, with a conventional cutting seton. METHODS: A total of 34 patients were randomized between 1998 and 2002. They were prospectively assessed by continence score and anorectal manometry, and for anal function, clinical sepsis and fistula recurrence. RESULTS: There was no difference in postoperative continence score, incidence of recurrent fistula or healing time between groups after a mean follow-up of 12 months. Resting anal manometric pressures and vector volumes were consistently higher with the modified seton (although not statistically significant), as was the area under the inhibitory curve during elicitation of the rectoanal inhibitory reflex across the full sphincter length. ( p<0.05). CONCLUSION: A larger prospective study of internal anal sphincter-preserving seton use in cryptogenic high transshincteric fistula-in-ano appears justified.

Adult↗
PubMed2003

Treatment of oesophageal cancer with preoperative chemoradiotherapy may increase operative mortality.

AIMS: This phase II multicentric study evaluates a modified preoperative chemoradiotherapy schedule. METHODS: Patients <75 years with potentially resectable neoplasm were eligible. Treatment included an initial course of CDDP 100 mg/m2 (Day 1) and 5-FU CI 5000 mg/m2 (Days 1-5) followed by 45 Gy (Days 28-63) and 5-FU CI 5000 mg/m2 (Days 28-33), CDDP 75 mg/m2 (Day 56) and 5-FU CI 3750 mg/m2 (Days 56-61). Regional lymph nodes were irradiated. RESULTS: Nineteen patients were studied. Oesophagectomy was performed in 17. Clear margins were achieved in 16 of these. Eight patients showed a pathologic complete response (pCR). One patient died of infection during the preoperative treatment and four died due to acute surgical complications. The study was closed prematurely because of excessive mortality. Median follow-up was 19 months. Local and regional relapse occurred in one and three patients, respectively. Median time and actuarial 3-year of overall survival and progression free rates were 18.6 months and 28%, and 12.7 months and 10.4%, respectively. CONCLUSIONS: This schedule showed a high pCR, resectability and local control rate. Treatment-related mortality limits its clinical applicability, but further investigations are warranted.

Adenocarcinoma↗
PubMed2002

Capecitabine named-patient programme for patients with advanced breast cancer. the UK experience.

Following the encouraging results achieved with the oral fluoropyrimidine capecitabine in clinical trials, a named patient programme was initiated in the UK, through which patients with advanced breast cancer were prescribed capecitabine monotherapy. In this programme, patients were treated with the standard dose of oral capecitabine (1250 mg/m(2) twice daily on days 1-14 of a 21-day treatment cycle). Efficacy and safety data were collected and analysed from 102 patients receiving outpatient treatment with capecitabine. All patients had previously received chemotherapy and for the majority (75%) this was in the metastatic setting. In total, 482 treatment cycles were administered, with a median of 4.5 treatment cycles (range 1-22) per patient. Tumour responses were observed in 20 patients (20%), with an additional 47 patients (46%) achieving disease stabilisation. The median time to disease progression was 4.1 months and median overall survival was 7.7 months. The most common treatment-related adverse events were palmar-plantar erythrodysaesthesia (PPE) (36%) and gastrointestinal toxicities (diarrhoea (33%) and nausea (24%)). Dose reductions due to adverse events were required in 33% of patients, but capecitabine was administered without a dose reduction for 90% of cycles. The results achieved with capecitabine in this named-patient programme confirm that, under 'real practice' conditions, capecitabine is active and well tolerated in patients with advanced breast cancer.

Adult↗
PubMed2001

Fungal infections in patients with solid tumors treated with high-dose chemotherapy and autologous peripheral blood stem cell transplantation.

The incidence and risk factors for fungal infection were assessed in 291 patients who had solid tumors and were undergoing autologous peripheral blood stem cell transplantation. The first 162 patients received prophylactic itraconazole, and 129 patients received nystatin. Empiric amphotericin B was given at day 7 of febrile neutropenia. Fungal infections developed in 52 patients: 47 (16%) were superficial and 6 (2%) were systemic. Itraconazole prophylaxis and only a few days of febrile neutropenia were independently associated with a decrease in the incidence of superficial infections. Only two patients required empiric amphotericin B. Systemic antifungal prophylaxis does not seem to be justified for patients with solid tumors and autologous peripheral blood stem cell transplantation. Empiric amphotericin B may be safely started at day 7 of febrile neutropenia.

Adolescent↗
PubMed2001

E400P in advanced seminoma of good prognosis according to the international germ cell cancer collaborative group (IGCCCG) classification: the Spanish Germ Cell Cancer Group experience.

PURPOSE: To evaluate the efficacy and toxicity of primary chemotherapy with the schedule E400P in the treatment of patients with early stage II (IIa and IIb) and advanced seminoma of good prognosis according to the international classification (IGCCCG). PATIENTS AND METHODS: Sixty-four patients were included. E400P consisted of cisplatin 25 mg/m2/day and etoposide 100 mg/m2/day for four days, every three weeks. Royal Marsden stages were IIab: 53% and IIc-IV: 47%. Twenty-three percent had high BHCG levels, twenty-seven percent had LDH > 2 x N. Sixty-two patients were of good prognosis according to the Medical Research Council classification. RESULTS: Response rate was 98% (69% complete remission, 29% residual disease). After a median follow-up of 34 months, treatment failure was seen in 7 patients (11%). Neutropenia (32%) was the most relevant grade 3-4 toxicity. Other important grade 3-4 side effects were found in less than 5%. Three-year time to treatment failure (TTF) was 89% (95% confidence intervals (CI): 80%-97%) for all patients, 91% (95% CI: 80%-99%) for stages IIa-b, and 87% (95% CI: 74%-99%) for stages IIc-IV. Three-year overall survival (OS) was 97% (95% CI: 93%-99%) for all patients and 95% (95% CI: 85%-99%) for stages IIa-b. CONCLUSIONS: E400P was a very active and safe regimen in good-prognosis advanced seminoma, with low toxicity rates. Definitive comparisons of this regimen with radiotherapy in stages IIa-b or with the more standard E500P or BEP, could be of interest.

Adult↗
PubMed2001

Binding of Amadori glucose-modified albumin by the monocytic cell line MonoMac 6 activates protein kinase C epsilon protein tyrosine kinases and the transcription factors AP-1 and NF-kappaB.

An affinity purification procedure is employed for the isolation of FL-specific binding proteins from MM6 cell membranes using magnetobeads coated with glycated polylysine and elution with FL and glycated 6-aminocaproic acid. Two main binding proteins were identified as membrane-bound nucleolin and cellular myosin heavy chain, which are glycosylated. This study shows that in these cells binding of short-term glycated albumin leads to activation of PKC, especially its isoform epsilon and this is linked to translocation of AP-1 and NF-kappaB into the nucleus. Consequently, an increased formation of IL-1ss mRNA is observed. The PKC inhibitor GO6976 prevents all these effects. Glycated albumin also stimulates activation of PTK. The PTK inhibitor genistein prevents activation of AP-1 indicating that PTK is also involved in this process, whereas NF-kappaB translocation is only dependent on PKC activation.

Carrier Proteins↗
PubMed2001

Inefficacy of burst-suppression anesthesia in medication-resistant major depression: a controlled trial.

Burst-suppression anesthesia (BSA) has been previously compared with electroconvulsive therapy (ECT) in drug-resistant depression, with promising results. We have carried out a double-blind randomized clinical trial comparing BSA with sham-BSA in 20 patients meeting DSM-IV criteria for major depression with inadequate response to antidepressant drugs and who chose BSA as an alternative to ECT. After withdrawing antidepressant drugs, patients were randomized to receive four sessions of either BSA (induction with propofol followed by the anesthetic agent sevoflurane, achieving BSA for 1 hour) or sham-BSA (induction with propofol until loss of consciousness, followed by spontaneous awakening in 5-10 minutes). Decrease in the Hamilton Rating Depression Scale was larger with BSA (-6.0 +/- 7.3) than with sham-BSA (-2.5 +/- 4.5), but differences did not reach statistical significance ( t = -1.08, p = 0.3). In our sample, we have not found BSA to be superior to sham-BSA and therefore cannot consider BSA as an alternative to ECT.

Adult↗
PubMed2001

Differential gene expression during capillary morphogenesis in 3D collagen matrices: regulated expression of genes involved in basement membrane matrix assembly, cell cycle progression, cellular differentiation and G-protein signaling.

We have performed a screening analysis of differential gene expression using a defined in vitro model of human capillary tube formation. Gene array, differential display and cDNA library screening were used to identify both known and novel differentially expressed genes. Major findings include: the upregulation and functional importance of genes associated with basement membrane matrix assembly; the upregulation of growth factors, transcription factors, anti-apoptotic factors, markers of endothelial cell differentiation, JAK-STAT signalling molecules, adhesion receptors, proteinase inhibitors and actin regulatory proteins; and expression changes consistent with inhibition of cell cycle progression, increased cholesterol biosynthesis, decreased ubiquitin-proteasome mediated degradation, and activation of G-protein signaling pathways. Using DNA microarray analysis, the most induced genes at 8, 24 and 48 hours compared with those at 0 hours were jagged-1, stanniocalcin and angiopoietin-2, whereas the most repressed genes were connective tissue growth factor, fibulin-3 and RGS-5. In addition, the full length coding sequence of two novel regulated capillary morphogenesis genes (CMGs) are presented. CMG-1 encodes a predicted intracellular 65 kDa protein with coiled-coil domains. A CMG-1-green fluorescent protein (GFP) chimera was observed to target to an intracellular vesicular compartment. A second novel gene, CMG-2, was found to encode a predicted intracellular protein of 45 kDa containing a transmembrane segment and a CMG-2-GFP chimera was observed to target to the endoplasmic reticulum. A recombinant portion of CMG-2 was found to bind collagen type IV and laminin, suggesting a potential role in basement membrane matrix synthesis and assembly. These data further elucidate the genetic events regulating capillary tube formation in a 3D matrix environment.

Amino Acid Sequence↗
PubMed2001

Matrix metalloproteinase-1 and -9 activation by plasmin regulates a novel endothelial cell-mediated mechanism of collagen gel contraction and capillary tube regression in three-dimensional collagen matrices.

Here, we describe a new function for plasmin and matrix metalloproteinases (MMPs), which is to regulate the regression of capillary tubes in three-dimensional extracellular matrix environments. Using a well-described capillary morphogenesis system in three-dimensional collagen matrices, a new model of capillary regression has been established by adding plasminogen to the culture medium. Plasminogen is converted to plasmin by endothelial cell plasminogen activators which then induces matrix metalloproteinase-dependent collagen gel contraction and capillary regression. Plasminogen addition results in activation of MMP-1 and MMP-9, which then results in collagen proteolysis followed by capillary regression. The endothelial cells undergo apoptosis following gel contraction as detected by flow cytometric analysis as well as by detectable caspase-3 cleavage and caspase-dependent cleavage of the actin cytoskeletal regulatory protein, gelsolin. In addition, directly correlating with the contraction response, tyrosine phosphorylation of p130cas, an adapter protein in the focal adhesion complex, is observed followed by disappearance of the protein. Proteinase inhibitors that block MMPs (TIMP-1 or TIMP-2), plasminogen activators (PAI-1) or plasmin (aprotinin) completely block the gel contraction and regression process. In addition, chemical inhibitors of MMPs that block capillary regression also block MMP-1 and MMP-9 activation suggesting that a key element in this regression response is the molecular control of MMP activation by endothelial cells. Blocking antibodies directed to MMP-1 or MMP-9 interfere with capillary regression while blocking antibodies directed to PAI-1 accelerate capillary regression suggesting that endogenous synthesis of PAI-1 negatively regulates this process. These data present a novel system to study a new mechanism that may regulate regression of capillary tubes, namely, plasmin and MMP-mediated degradation of extracellular matrix.

Antibodies↗
PubMed2001

Biological activity of Ruta chalepensis (Rutaceae) and Sechium pittieri (Cucurbitaceae) extracts on Hypsipyla grandella (Lepidoptera: Pyralidae) larvae.

Biological activity of a plant extract (common rue, Ruta chalepensis) and a semi purified fraction (from "tacaco cimarrón", Sechium pittieri) on mahogany shootborer larvae (Hypsipyla grandella) was studied. A randomized complete block design, with four replications, was used. H. grandella third instar larvae were exposed for 24 h to Cedrela odorata leaf discs dipped in several treatment dissolutions of each extract (0.1, 0.32, 1.0, 3.20, and 10%); afterwards, each larva was transferred to a flask containing an artificial diet and was allowed to complete its development. Variables measured included food consumption (foliar area eaten in 24 h), mortality, and developmental effects (developmental time for each larval instar and the pupa, and pupal weight). The common rue extract showed a clear antifeedant activity at a concentration as low as 0.32%, whereas the "tacaco cimarrón" fraction caused toxicity, especially at the two highest concentrations (3.20 and 10%).

Analysis of Variance↗