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T Gonzalez

Publications and source records attributed to T Gonzalez.

At least 19 recordsLinked to original sources
PubMed2006

Synthesis of metallothionein-mimic decapeptides with heavy atom signaling properties.

The automated parallel solid-phase synthesis of a 17-member library of metallothionein-mimic decapeptides carrying a Lariat ether group is described. The peptides were synthesized in good yield and the identity and quality of each product were performed by mass spectrometry and IR. Subsequently, in the presence of europium(III) ions as fluorescent reporter, each compound was screened, both attached to the resin and cleaved off, for their sensing behavior towards metal ions (Cd(2+),Hg(2+), Cu(2+), Mg(2+) and Ca(2+)) using fluorimetric techniques. Several of these Cys-enriched synthetic peptides showed surprisingly low detection limits for Cd(2+) and Hg(2+). The analytical potential of these metallothionein-mimic decapeptides as metal ion recognition materials for sensor development is outlined. Finally, the sensing response mechanism, based on an energy transfer process and a metal ion allosteric interaction, is proposed.

Allosteric Site↗
PubMed2004

Alteration in insulin action: role of IRS-1 serine phosphorylation in the retroregulation of insulin signalling.

Insulin resistance, when combined with impaired insulin secretion, contributes to the development of type 2 diabetes. Insulin resistance is characterised by a decrease in insulin effect on glucose transport in muscle and adipose tIssue. Tyrosine phosphorylation of insulin receptor substrate 1 (IRS-1) and its binding to phosphatidylinositol 3-kinase (PI 3-kinase) are critical events in the insulin signalling cascade leading to insulin-stimulated glucose transport. Modification of IRS-1 by serine phosphorylation could be one of the mechanisms leading to a decrease in IRS-1 tyrosine phosphorylation, PI 3-kinase activity and glucose transport. Recent findings demonstrate that "diabetogenic" factors such as FFA, TNFalpha, hyperinsulinemia and cellular stress, increase the serine phosphorylation of IRS-1 and identified Ser307/612/632 as phosphorylated sites. Moreover, several kinases able to phosphorylate these serine residues have been identified. These exciting results suggest that serine phosphorylation of IRS-1 is a possible hallmark of insulin resistance in biologically insulin responsive cells or tIssues. Identifying the pathways by which "diabetogenic" factors activate IRS-1 kinases and defining the precise role of serine phosphorylation events in IRS-1 regulation represent important goals. Such studies may enable rational drug design to selectively inhibit the activity of the relevant enzymes and generate a novel class of therapeutic agents for type 2 diabetes.

Animals↗
PubMed2004

HTLV-1 modifies the clinical and immunological response to schistosomiasis.

The immunological response in HTLV-1 infected individuals is characterized by a prominent Type-1 cytokine response with high production of IFN-gamma and TNF-alpha. In contrast, helminthic infections and in particular chronic schistosomiasis are associated with a predominant production of IL-4, IL-5, IL-10 and IL-13. Liver fibrosis is the main pathological finding in schistosomiasis that occurs after many years of infection. This pathology is T cell dependent but the immune response mechanisms are not completely understood. The North-east region of Brazil is endemic for both HTLV-1 and schistosomiasis. In the present study the immune response, clinical severity, and therapeutic response to praziquantel of patients with schistosomiasis coinfected with HTLV-1 were compared with patients infected only with S. mansoni. Patients with HTLV-1 and S. mansoni had lower levels of IL-5 (P < 0.05) and higher levels of IFN-gamma (P < 0.05) in cultures stimulated with S. mansoni antigen and decreased S. mansoni antigen specific IgE levels when compared with patients with schistosomiasis without HTLV-1 coinfection. Liver fibrosis was mild in all HTLV-1 coinfected patients and efficacy of praziquantel was lower in patients dually infected than in patients infected only with S. mansoni.

Adult↗
PubMed2003

MAP kinases and mTOR mediate insulin-induced phosphorylation of insulin receptor substrate-1 on serine residues 307, 612 and 632.

AIM/HYPOTHESIS: Insulin-induced IRS-1 serine phosphorylation could be physiologically important to regulate insulin action. In a hyperinsulinaemic state such as obesity or Type 2 diabetes, this phosphorylation could be modified and exacerbate insulin resistance. We aimed at identifying serine residues in IRS-1 phosphorylated in response to insulin stimulation and at determining the involved kinases. METHODS: 3T3-L1 adipocytes, muscle and adipose tissue of mice were subjected to Western Blot analysis with phosphospecific antibodies to identify phosphorylation sites in IRS-1 following insulin treatment. Pharmacological inhibitors were used to determine the serine kinases involved in this phosphorylation. RESULTS: In 3T3-L1 adipocytes, insulin promoted the phosphorylation of serine 307, 612 and 632 with Serine(612/632) more rapidly phosphorylated than Serine(307). Insulin-induced phosphorylation of Serine(307) was dependent on the activation of a PI 3-kinase/mTOR pathway. The phosphorylation of Serine(612/632) required the activation of the MAP kinase pathway following short-term insulin stimulation and activation of the PI 3-kinase/mTOR pathway following prolonged insulin stimulation. Phosphorylation of Serine(307) and Serine(632) occurred in vivo in skeletal muscle and white adipose tissue of mice injected with insulin and was dependent on the activation of mTOR. Moreover, inhibition of mTOR led to a persistent PI 3-kinase activation by insulin. CONCLUSION/INTERPRETATION: Insulin-induced IRS-1 serine phosphorylation is a complex process involving different sites and kinases. This complexity could be physiologically important to accurately regulate insulin signalling. Abnormal phosphorylation of these serine residues in hyperinsulinaemic state could participate in the down-regulation of insulin signalling.

3T3 Cells↗
PubMed2003

Fatty acid-induced insulin resistance: role of insulin receptor substrate 1 serine phosphorylation in the retroregulation of insulin signalling.

Insulin resistance, when combined with impaired insulin secretion, contributes to the development of type 2 diabetes. Insulin resistance is characterized by a decrease in the insulin effect on glucose transport in muscle and adipose tissue. Tyrosine phosphorylation of IRS-1 (insulin receptor substrate 1) and its binding to PI 3-kinase (phosphoinositide 3-kinase) are critical events in the insulin signalling cascade leading to insulin-stimulated glucose transport. Various studies have implicated lipids as a cause of insulin resistance in muscle. Elevated plasma fatty acid concentrations are associated with reduced insulin-stimulated glucose transport activity as a consequence of altered insulin signalling through PI 3-kinase. Modification of IRS-1 by serine phosphorylation could be one of the mechanisms leading to a decrease in IRS-1 tyrosine phosphorylation, PI 3-kinase activity and glucose transport. Recent findings demonstrate that non-esterified fatty acids, as well as other factors such as tumour necrosis factor alpha, hyperinsulinaemia and cellular stress, increase the serine phosphorylation of IRS-1 and identified Ser(307) as one of the phosphorylated sites. Moreover, several kinases able to phosphorylate this serine residue have been identified. These exciting results suggest that Ser(307) phosphorylation is a possible hallmark of insulin resistance in biologically insulin-responsive cells or tissues. Identification of IRS-1 kinases could enable rational drug design in order to selectively inhibit the activity of the relevant enzymes and generate a novel class of therapeutic agents for type 2 diabetes.

Animals↗
PubMed2001

Expression of a mineral phosphate solubilizing gene from Erwinia herbicola in two rhizobacterial strains.

A genetic construction was carried out using the broad host range vector pKT230 and plasmid pMCG898, which encodes the Erwinia herbicola pyrroloquinoline quinone (PQQ) synthase, a gene involved in mineral phosphate solubilization (mps). The final construction was transformed and expressed in Escherichia coli MC1061, and the recombinant plasmids were transferred to Burkholderia cepacia IS-16 and Pseudomonas sp. PSS recipient cells by conjugation. Clones containing recombinant plasmids produced higher clearing halos in plates with insoluble phosphate as the unique (P) source, in comparison with those of strains without plasmids, demonstrating the heterologous expression of the E. herbicola gene in the recipient strains. This genetic manipulation allowed the increase in mps ability of both strains, enhancing their potentialities as growth promoters of agricultural crops. These results represent the first report on the application of the recombinant DNA methodology for the obtaining of improved phosphate solubilizing ability from rhizobacterial strains for biofertilization purposes.

Biotechnology↗
PubMed2001

Adapting pharmacokinetic properties of a humanized anti-interleukin-8 antibody for therapeutic applications using site-specific pegylation.

A neutralizing anti-interleukin-(IL-)8 monoclonal antibody was humanized by grafting the complementary determining regions onto the human IgG framework. Subsequent alanine scanning mutagenesis and phage display enabled the production of an affinity matured antibody with a >100-fold improvement in IL-8 binding. Antibody fragments can be efficiently produced in Escherichia coli but have the limitation of rapid clearance rates in vivo. The Fab' fragment of the antibody was therefore modified with polyethylene glycol (PEG) in order to obtain a more desirable pharmacokinetic profile. PEG (5-40 kDa) was site-specifically conjugated to the Fab' via the single free cysteine residue in the hinge region. In vitro binding and bioassays showed little or no loss of activity. The pharmacokinetic profiles of the 20 kDa, 30 kDa, 40 kDa, and 40 kDa branched PEG-Fab' molecules were evaluated in rabbits. Relative to the native Fab', the clearance rates of the PEGylated molecules were decreased by 44-175-fold. In a rabbit ear model of ischemia/reperfusion injury, all PEGylated Fab' molecules were as efficacious in reducing oedema as the original monoclonal antibody. These studies demonstrate that it is possible to customize the pharmacokinetic properties of a Fab' while retaining its antigen binding activity.

Alanine↗
PubMed2000

Isolation of a gene from Burkholderia cepacia IS-16 encoding a protein that facilitates phosphatase activity.

A genomic library from Burkholderia cepacia IS-16 was constructed in Escherichia coli by partial Sau3AI digestion of the chromosomal DNA, with the plasmid vector Bluescript SK. This library was screened for clones able to grow as green stained colonies on selective medium developed for detecting phosphatase-positive colonies. Three green-stained clones (pFS1, pFS2, and pFS3) carried recombinant plasmids harboring DNA inserts of 5.0, 8.0, and 0.9 kb, respectively. DNA hybridization experiments demonstrated the presence of overlapping DNA fragments in the three clones and that these three clones were all derived from Burkholderia cepacia IS-16 genomic DNA. DNA sequence analysis, together with polyacrylamide gels of proteins encoded by E. coli containing pFS3, suggested that the isolated 0. 9-kb DNA fragment encodes the functional portion of a phosphate transport protein.

Amino Acid Sequence↗
PubMed1999

Short-term cyclosporine induces a remission of autoimmune hepatitis in children.

BACKGROUND/AIMS: The current immunosuppressive treatment of patients with autoimmune hepatitis consists of prednisone and azathioprine. High doses of prednisone used to obtain the remission of the disease are associated with serious adverse effects. To avoid harmful consequences of prednisone therapy, we proposed to treat patients with oral cyclosporine to obtain the remission of the inflammatory process. METHODS: This is a pilot, multinational, multicenter, clinical trial involving children with autoimmune hepatitis. Thirty-two children were recruited, who according to international criteria were considered as having definite autoimmune hepatitis. Cyclosporine alone was administered for 6 months, followed by combined low doses of prednisone and azathioprine for 1 month, after which cyclosporine was discontinued. Biochemical remission of the disease was established by the follow-up of serum transaminase activity levels. Growth parameters and adverse effects of the treatment were recorded. RESULTS: Two patients were withdrawn from the study: one for non-compliance and the other for liver failure which did not improve with cyclosporine. Of the 30 remaining patients, 25 normalized alanine aminotransferase activity levels by 6 months and all the patients by 1 year of treatment. Z-scores for height showed a trend towards improvement during treatment. Adverse effects of cyclosporine were mild and disappeared during weaning off the medication. CONCLUSIONS: Cyclosporine induced the biochemical remission of the hepatic inflammatory/necrotic process in children with autoimmune hepatitis, with few and well-tolerated adverse effects.

Adolescent↗
PubMed1996

Epidemiology of renal involvement in type II diabetics (NIDDM) in Catalonia. The Catalan Diabetic Nephropathy Study Group.

The aim of this cross-sectional study was to establish the prevalence of renal involvement and to identify associations with its most important possible risk factors in a group of patients with Type II diabetes mellitus, representative of the population living in Catalonia. One thousand two hundred and three patients (47% males, mean age: 61 +/- 6 years, diabetes duration 9 +/- 6 years) were studied. Overnight urine samples were collected to determine urinary albumin excretion (UAE). If UAE was > 15 micrograms/min, a new 24-h urine collection for UAE measurement to establish the existence of microalbuminuria (20-200 micrograms/min) or macroalbuminuria (> 200 micrograms/min) was obtained. Clinic and metabolic evaluations were also performed. The prevalence (%) of microalbuminuria, macroalbuminuria and hypertension were, respectively, 23. 1, 5.4 and 42. In comparison with normoalbuminurics, patients with microalbuminuria were predominately male (P < 0.03), with a significantly higher systolic (P < 0.001) and diastolic (P < 0.001) blood pressure and body mass index (P < 0.001). The prevalence of smokers (former + current) was higher in patients with microalbuminuria (43 vs 32%, P < 0.025). Moreover, patients with nephropathy had more prevalence of retinopathy (P < 0.001), neuropathy (P < 0.001), peripheral angiopathy (P < 0.001) and coronary disease (P < 0.001). The prevalence of microalbuminuria in Type II diabetes in Catalonia is similar to that observed in other european countries. The existence of microalbuminuria is associated with several diabetic complications, as well as tobacco consumption and obesity.

Aged↗
PubMed1996

Histopathological changes in the reproductive organs of Manchego ewes grazing on lucerne.

The effects of prolonged exposure to phyto-oestrogens (coumestrol) on the morphology of the reproductive organs of ewes were studied in 28 lucerne-grazing animals, and compared with 28 control ewes given a standard coumestrol-free diet. The anatomical studies showed that 43% of the ewes fed lucerne displayed macroscopic changes within the genital tract, of which the uterine alterations were especially prominent. The microscopic examination of the test group ewes identified specific histopathological features of the uterus and cervix. A greater than normal development of the cervical folds was observed, as well as cystic formations of different sizes whose content was eosinophilic. In the rest of the uterus, more glandular activity was detected in the lucerne-grazing group than in the control ewes, although cystic formations were not seen.

Animals↗
PubMed1995

Identification of amino acids in the CD11a I-domain important for binding of the leukocyte function-associated antigen-1 (LFA-1) to intercellular adhesion molecule-1 (ICAM-1)

Leukocyte function-associated antigen-1 (LFA-1) is a cell surface adhesion receptor for intercellular adhesion molecule-1, -2, and -3 (ICAM-1, -2, -3). Using human/murine chimeras of the I-domain of the LFA-1 alpha subunit (CD11a), we recently identified the epitopes recognized by eight monoclonal antibodies against CD11a that inhibit LFA-1 binding to ICAM-1. In this report, we determined that replacement of the entire human I-domain with the entire murine I-domain in CD11a completely abrogated LFA-1 binding to human ICAM-1 without affecting the gross conformation or heterodimer formation of LFA-1, as assayed by antibody binding. In order to assess which residues of the I-domain are responsible for binding to ICAM-1, we tested the ability of a panel of human/murine I-domain chimeras to bind to human ICAM-1. When complexed with CD18, all CD11a chimeras bound ICAM-1 at levels comparable to wild-type CD11a/CD18, indicating that the residues in these chimeras which differ in human and murine I-domains may not play a critical role in LFA-1 binding to ICAM-1. A series of point mutations of residues that are conserved between murine and human CD11a I-domains, as well as between CD11b and CD11c, were also generated. Substitution of alanine for proline at position 192 in the human CD11a I-domain abrogated adhesion of LFA-1 to ICAM-1. Antibody binding data suggested that this was due to conformational changes within the I-domain. Mutation of the aspartic acids at positions 137 and 239 to either alanine or lysine completely destroyed ICAM-1 binding. The conformation of LFA-1 alanine mutants was not significantly altered. This suggests that these aspartic acids are required for binding of human LFA-1 to human ICAM-1.

Animals↗
PubMed1994

X-ray structures of fragments from binding and nonbinding versions of a humanized anti-CD18 antibody: structural indications of the key role of VH residues 59 to 65.

X-ray crystal structures of fragments from two different humanized anti-CD18 antibodies are reported. The Fv fragment of the nonbinding version has been refined in space group C2 with a = 64.2 A, b = 61.3 A, c = 51.8 A, and beta = 99 degrees to an R-value of 18.0% at 1.9 A, and the Fab fragment of the tight-binding version has been refined in space group P3 with a = 101. A and c = 45.5 A to an R-value of 17.8% at 3.0 A resolution. The very large difference in their binding affinity (> 1000-fold) is attributed to large and local structural differences in the C-terminal part of CDR-H2, and from this we conclude there is direct contact between this region and antigen when they combine. X-ray structures of antibody-antigen complexes available in the literature have yet to show this part of CDR-H2 in contact with antigen, despite its hypervariable sequence. Implications of this result for antibody humanization are discussed.

Amino Acid Sequence↗
PubMed1993

The use of polymorphic Alu insertions in human DNA fingerprinting.

We have characterized several Human Specific (HS) Alu insertions as either dimorphic (TPA25, PV92, APO), slightly dimorphic (C2N4 and C4N4) or monomorphic (C3N1, C4N6, C4N2, C4N5, C4N8) based on studies of Caucasian, Asian, American Black and African Black populations. Our approach is based upon: 1) PCR amplification using primers complementary to the unique DNA sequences that flank the site of insertion of the different Alu elements studied; 2) gel electrophoresis and scoring according to the presence or absence of an Alu insertion in one or both homologous chromosomes; 3) allele frequencies determined by gene counting and compared to Hardy-Weinberg expectations. Our DNA fingerprinting procedure using PCR amplification of diallelic polymorphic (dimorphic) Human Specific Alu insertions, may be used as a tool for genetic mapping, to characterize populations, study human migrational patterns, and track the inheritance of human genetic disorders.

DNA Fingerprinting↗
PubMed1992

[Cardiac output studied by a non invasive method in hypertensive patients].

We measured by thoracic bioimpedance (BoMed, NCCOM3-R7) non invasive cardiac index (CI), stroke index (SI) and systemic vascular resistance index (SVRI) in 48 hypertensive patients (OMS) compared to 30 normotensive. The mean arterial pressure (MAP) and the SVRI were significantly higher in the hypertensive group while the CI are significantly lower, as that was shown in previous invasive studies. We found an inverse correlation between age and CI (r = -.30, p < or = .05) in relation with a negative correlation between SI and age (r = -.35, p < or = .05) and no correlation between heart rate and age. Furthermore we divided normotensive and hypertensive patients in three groups of CI (low CI < 2.8 l/min/m2, 2.8 < or = normal CI < or = 4.2 l/min/m2, high CI > 4.2 l/min/m2) and in three groups of SVRI (low SVRI < 1660 Flohms/m2, 1660 < or = normal SVRI < or = 2580 Flohms/m2, high SVRI > 2580 Flohms/m2). Despite CI diminution in hypertension, high CI percentage's was the same in normotensive and hypertensive patients. In conclusion, these results confirm previous studies by using a simple, easy, non invasive and reproducible method.

Adult↗
PubMed1991

[Cardiac mass, ventricular relaxation parameters and their correlation with blood pressure during rest and ambulatory monitoring].

UNLABELLED: A resting blood pressure (Dynamap, 8AM-8PM, one recording every 15 minutes) has been recorded among 60 patients; mean age: 51 +/- 14 years (24 females, 36 males; 3 normotensive and 57 hypertensive WHO) and a echocardiogram TM and two-dimensional with doppler in order to measure the interventricular septum thickness, Left Ventricular Posterior Wall Thickness and the left Ventricular Internal diameter with which we can calculate the myocardial mass (MM, Devereux formula) and the myocardial mass index using the body surface. Furthermore ventricular relaxation has been studied (A/E, PHT) by using doppler echocardiogram. During the same week an ambulatory blood pressure (Nippon Colin 8AM-8PM one reading every 15 minutes) has been recorded. The blood variables are the mean of the recording, systolic, diastolic, mean. We have confirmed the conclusion between blood pressure and left ventricular mass by using resting and ambulatory blood pressure recordings. But it does not exist any significant difference within we compare the correlations coefficients (Hotteling's Test with Williams modification) obtained with two devices. In revenge this difference exists with ventricular relaxation index A/E to MBP: mMBPr = 0.51, mMBPa = 0.34 (p less than 0.05), and PHT to MBP: mMBPr = 0.49, mMBPa = 0.31, (p less than 0.05) and to the SBP: mSBPr = 0.54, mSBPa = 0.35, (p less than 0.05). CONCLUSION: the relationship between blood pressure and myocardial mass and by, the heart effect from hypertension can be studied by using in any case resting and ambulatory blood pressure recordings. This will confirm the hypothesis in which the blood pressure recordings multiplication is more important than the way of recording it.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Familial articular chondrocalcinosis in Spain.

One hundred and one first degree relatives of 35 patients with chondrocalcinosis were examined for the presence of familial disease. Eleven subjects from nine families showed radiological chondrocalcinosis, a prevalence of familial disease of 26%. Two different patterns of disease were noted--the older generation was more commonly affected, and the younger generation and second degree relatives were exempt. Clinical and radiological differences were found between the early and late onset groups, but not between late onset and sporadic forms of chondrocalcinosis. These findings support the suggestion that the true prevalence of familial disease. is underestimated. A dominant, autosomal transmission with variable penetrance is consistent with our findings, which suggests that homozygous patients with familial chondrocalcinosis may present a more severe form of the disease.

Adult↗