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J Bustamante

Publications and source records attributed to J Bustamante.

At least 37 records · Page 2Linked to original sources
PubMed1999

Biochemistry and pharmacology of rabbit cardiac growth hormone (GH) receptors.

In this report we present the first in-depth description of the biochemical and pharmacological properties of rabbit cardiac GH receptors. The apparent M(r)'s of the [125I]human (h) GH-receptor complexes were 380, 205, 90, 62, 52 and 38 kDa as demonstrated by an autoradiograph of affinity-labelled cardiac GH receptors separated under non-reducing conditions by SDS PAGE. The [125I]hGH-cardiac GH receptor complexes were disulfide-linked since the M(r)s of the complexes diminished to 170, 116, 97, 71, 45 and 38 kDa under reducing conditions, indicating the presence of multiple receptors, receptor-associated macromolecules or receptor and ligand in various ratios. The pharmacology of cardiac GH receptors is not typical of GH receptors present in other tissues. In radio receptor assays, both bovine GH and ovine prolactin were 50-fold and 100-fold less potent, respectively, than unlabelled hGH, in blocking the binding of [125I]hGH to cardiac binding sites and were, therefore, extremely weak antagonists. Similarly, neither bovine GH nor ovine prolactin blocked the [125I]hGH affinity-labelling of cardiac GH receptors compared to equivalent doses of unlabelled hGH. Parameters which characterize the kinetics for the association, dissociation and equilibrium binding of [125I]hGH to cardiac GH receptors were ascertained. Association kinetics for the binding of [125I]hGH to heart GH receptors exhibited a maximum specific binding at 17 h and 25 degrees C. The association of [125I]hGH to heart GH receptors was reversible with approximately 15 h required for half of the specifically bound [125I]hGH to dissociate. The coupling of [125I]hGH to heart GH receptors was optimum at pH 6 and the strength of the equilibrium binding, as measured by the ED50, was approximately 2 ng/ml. These data indicate that the cardiac GH receptors are pharmacologically distinct and that there is a M(r) heterogeneity in the [125I]hGH receptor complexes.

Animals↗
PubMed1999

Natural history of untreated nonsurgical hepatocellular carcinoma: rationale for the design and evaluation of therapeutic trials.

This study analyzed the natural history and prognostic factors of patients with nonsurgical hepatocellular carcinoma (HCC). Twenty variables from 102 cirrhotic patients with HCC who were not treated within prospective randomized controlled trials (RCT) were investigated through uni- and multivariate analyses. None of them was suitable for radical therapies (surgical resection, liver transplantation, or ethanol injection) or presented end-stage disease as reflected by an Okuda stage 3 or a Performance Status >/=3. Sixty-five patients were Child-Pugh A, 34 were B, and 3 were C. Most of them exhibited a preserved Performance Status Test (PST) (0 = 56; 1 = 38; 2 = 8). Tumor was solitary in 26 (</=5 cm in 16) and multinodular/massive in 76. After a median follow-up of 17 months, 79 patients died, the 1-, 2-, and 3-year survival being 54%, 40%, and 28%. The multivariate study identified PST (P =.01), constitutional syndrome (P =.04), vascular invasion (P =.001), and extrahepatic spread (P =.04) as independent predictors for mortality. The 1-, 2-, and 3-year survival for the 48 patients without adverse factors (Stage 0) was 80%, 65%, and 50%, respectively, and 29%, 16%, and 8% in the 54 patients with at least one adverse parameter (Stage I). Therefore, Stage 0 would correspond to an intermediate stage, while Stage I would represent an advanced status, before reaching an end-stage phase. In conclusion, the outcome of nonsurgical HCC is not homogeneously grim and may be predicted by assessing the presence of symptoms and of an invasive tumoral pattern. Therapeutic trials should be designed and evaluated considering these characteristics.

Adult↗
PubMed1999

Prognostic significance of hepatic encephalopathy in patients with cirrhosis.

BACKGROUND: There are numerous studies concerning the natural history and prognostic factors in cirrhosis, the results of which are useful in selecting liver transplant candidates. However, little attention has been paid to the prognostic significance of hepatic encephalopathy despite the high frequency of this complication. METHODS: We reviewed the charts of 111 cirrhotic patients who developed a first episode of acute hepatic encephalopathy to determine their survival probability and to identify prognostic factors. RESULTS: During follow-up (12+/-17 months), 82 (74%) patients died. The survival probability was 42% at 1 year of follow-up and 23% at 3 years. With univariate analyses followed by a multivariate analysis, 7 out of 30 clinical and standard laboratory variables were significantly associated with poor prognosis: male sex, increased serum bilirubin, alkaline phosphatase, potassium and blood urea nitrogen, and decreased serum albumin and prothrombin activity. Patients were classified into two groups according to a prognostic index calculated from these 7 variables. Survival probability at 1 and 3 years was 73% and 38%, respectively, in patients with a low prognostic index, and 10% and 3% in patients with a high prognostic index. CONCLUSION: Hepatic encephalopathy is associated with short survival in cirrhotic patients. Although these patients can be classified into several groups with a different prognosis, the survival probability in every group is lower than that currently expected after liver transplantation. Therefore, cirrhotic patients developing a first episode of acute hepatic encephalopathy should be considered as potential candidates for this therapeutic procedure.

Alkaline Phosphatase↗
PubMed1999

Oxidative stress in chronic renal failure.

This study focuses on the oxidative stress in patients with severe chronic renal failure who are not undergoing dialysis treatment. The erythocyte levels, creatinine clearing and plasma- and cell activities of the following enzymes were determined: glutathione peroxidase (Gpx), superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), and glutathione transferase (GT). The concentrations of non-enzyme molecules such as total glutathione in both oxidized and reduced forms, and malonyldialdehyde (MDA) were also measured. The obtained values were compared with those in healthy blood donors of comparable age and social status. The results indicate that chronic renal patients have lower glutathione levels and reduced activities of glutathione peroxidase and of glutathione reductase, while exhibiting elevated levels of malonyldialdehyde and activities of superoxide dismutase, glutathione transferase, and catalase. Finally, creatinine clearing was found to be correlated (p < 0.001) to total (oxidized and reduced) glutathione, Gpx and MDA. These observations may serve to establish a simple protocol for evaluation of renal function.

Biomarkers↗
PubMed1998

Divalent metal cation chelators enhance chromatographic separation of structurally similar macromolecules: separation of human growth hormone isoforms.

Human GH isoforms were separated by anion-exchange chromatography using a linear NaCl gradient in the presence and absence of EDTA and EGTA. SDS-PAGE showed that glycosylated 24-kDa hGH did not appreciably separate from other hGH variants in the absence of metal chelators. However, in the presence of metal chelators, glycosylated 24-kDa hGH separated from the bulk of the hGH isoforms. Human GH isoforms were also separated by size-exclusion chromatography in the presence and absence of metal chelators. Glycosylated 24-kDa hGH eluted with the bulk of the hGH isoforms in both separations. The inclusion of metal chelators in chromatographic buffers to alter the charge and/or size of proteins by stripping their metals may be a generally useful strategy in their fractionation.

Cations, Divalent↗
PubMed1998

Alpha-lipoic acid in liver metabolism and disease.

R-alpha-Lipoic acid is found naturally occurring as a prosthetic group in alpha-keto acid dehydrogenase complexes of the mitochondria, and as such plays a fundamental role in metabolism. Although this has been known for decades, only recently has free supplemented alpha-lipoic acid been found to affect cellular metabolic processes in vitro, as it has the ability to alter the redox status of cells and interact with thiols and other antioxidants. Therefore, it appears that this compound has important therapeutic potential in conditions where oxidative stress is involved. Early case studies with alpha-lipoic acid were performed with little knowledge of the action of alpha-lipoic acid at a cellular level, but with the rationale that because the naturally occurring protein bound form of alpha-lipoic acid has a pivotal role in metabolism, that supplementation may have some beneficial effect. Such studies sought to evaluate the effect of supplemented alpha-lipoic acid, using low doses, on lipid or carbohydrate metabolism, but little or no effect was observed. A common response in these trials was an increase in glucose uptake, but increased plasma levels of pyruvate and lactate were also observed, suggesting that an inhibitory effect on the pyruvate dehydrogenase complex was occurring. During the same period, alpha-lipoic acid was also used as a therapeutic agent in a number of conditions relating to liver disease, including alcohol-induced damage, mushroom poisoning, metal intoxification, and CCl4 poisoning. Alpha-Lipoic acid supplementation was successful in the treatment for these conditions in many cases. Experimental studies and clinical trials in the last 5 years using high doses of alpha-lipoic acid (600 mg in humans) have provided new and consistent evidence for the therapeutic role of antioxidant alpha-lipoic acid in the treatment of insulin resistance and diabetic polyneuropathy. This new insight should encourage clinicians to use alpha-lipoic acid in diseases affecting liver in which oxidative stress is involved.

Animals↗
PubMed1998

[Simultaneous presentation of autoimmune thyroiditis and celiac disease in an adult].

Celiac disease may be associated with other underlying autoimmune diseases. Among these, thyroid disease has been described in around 10% of the cases with hypothyroidism being the most frequently reported. Clinical suspicion of thyroid involvement in patients with celiac disease is difficult since the symptomatology is scarce or is masked by the picture of malabsorption. Nonetheless, its detection is important since it is not solved by gluten free diet and its correction requires specific treatment. Thyroid function studies, in addition to determination of antithyroglobulin and antimicrosomal antibodies, should be considered in celiac patients refractory to conventional dietetic treatment. We herein present the case of a 65-year-old woman who consulted for a malabsorption syndrome in whom celiac disease of the adult was simultaneously presented with hyperthyroidism secondary to autoimmune thyroiditis.

Aged↗
PubMed1997

The semiconductor elements arsenic and indium induce apoptosis in rat thymocytes.

Indium arsenide and gallium arsenide are important new materials in the semiconductor industry due to their superior electronic properties in comparison with the older silicon-based materials. Animal experiments have shown that exposure to these compounds induces marked alterations in gene expression and immune response. Toxicity to the immune system has frequently been related to T and B cell apoptosis. In the present study we show that the semiconductor elements indium (In) and arsenic (As) are able to induce apoptosis in rat thymocytes in vitro. The results show that exposure to InCl3 (1, 10, or 100 microM) or Na AsO2 (0.01, 0.1, or 1 microM) induced DNA laddering after 6 h of incubation without compromising cell viability. These results were corroborated by flow cytometry analysis of propidium iodide-loaded cells, showing a typical high hypodiploid DNA peak in apoptotic thymocytes. Higher doses of In (1 mM) or As (10-100 microM) induced cell death by necrosis. These data indicate that In and As can induce apoptosis and necrosis in T lymphocytes in a dose-dependent manner, which may be of relevance for their immunotoxicity.

Animals↗
PubMed1997

Early redox changes during rat thymocyte apoptosis.

Methylprednisolone (glucocorticoid hormone, MPS), etoposide (epipodophyllotoxin inhibitor of a topoisomerase II), and thapsigargin (inhibitor of the endoplasmic reticular Ca2+-ATPase) were used as apoptosis-inducing agents in rat thymocytes. Early redox changes were determined during the early phase of induced apoptosis. The three agents induced apoptosis as assessed by DNA laddering after agarose gel electrophoresis and by quantitative DNA fragmentation. Intracellular H2O2 steadystate concentrations after 30 min of incubation were 40, 48, 25, and 75 nM for control and MPS-, etoposide-, and thapsigargin-treated thymocytes, respectively. After 30 min of MPS and thapsigargin exposure, increased DCFH oxidation was clear compared with control cells, but no increase in dichlorofluorescein (DCF) was observed in etoposide-treated thymocytes. DCF fluorescence correlated linearly with the intracellular H2O2 concentration after 30 min of incubation. The amounts of thiobarbituric acid-reactive substances produced after 3 h of incubation and expressed as pmol/mg protein were 105+/-23, 120+/-18, 350+/-17, and 98+/-24 pmol/mg protein for untreated and MPS-, thapsigargin-, and etoposide-treated thymocytes, respectively. Common and marked reductions in intracellular glutathione of 46, 73, 58, and 39% were observed after 2 h of incubation with MPS-, thapsigargin-, and etoposide-treated cells and in untreated cells, respectively. A simultaneous increase in oxidized glutathione, compared with untreated cells, was evident in MPS (66%) and was stronger in thapsigargin-exposed cells (250%). A 55% decrease in GSSG in etoposide-treated cells was found. It is concluded that redox changes occur during the early phase of induced apoptosis in rat thymocytes and are not always associated with an oxidative stress. Rather, this situation is closely related with the type of stimuli.

Animals↗
PubMed1997

Pulmonary abscess as a complication of transarterial embolization of multinodular hepatocellular carcinoma.

Hepatic transarterial embolization has been widely used in the treatment of hepatocellular carcinoma and other liver tumors. Despite being a safe treatment, some complications associated with this procedure have been described. The most frequent adverse effect of transarterial embolization is postembolization syndrome, whereas infections account for only 3.4% of complication. We report the first case of lung abscess as a complication of transarterial embolization used in the treatment of multinodular hepatocellular carcinoma.

Carcinoma, Hepatocellular↗
PubMed1996

Glycosylated human growth hormone (hGH): a novel 24 kDa hGH-N variant.

We have identified a human pituitary protein as a novel glycosylated variant of hGH. Isolation of the denatured protein included separation of human pituitary extract by Sephadex G-100 chromatography in ammonium bicarbonate, followed by Sephadex G-100 chromatography in 10% acetic acid, with subsequent DEAE Sephacryl chromatography in ammonium bicarbonate, and finally by preparative SDS PAGE. The pituitary protein has a molecular weight of 24 kDa as determined by SDS PAGE analysis and is thus larger than the normal 22 kDa hGH. N-Terminal amino acid sequence analysis of the first twenty-six residues reveals that this protein is not derived from the hGH-V gene but is rather a hGH-N gene product. Assays for the detection of glycoconjugates (periodate oxidation, sialidase treatment, trifluoromethanesulfonic acid treatment) indicate that the hGH variant has carbohydrate moieties. The discovery of new hGH raises questions about the role of glycosylation in the structure/function relationships of this hormone.

Amino Acid Sequence↗
PubMed1996

Diabetes mellitus after liver transplantation: prevalence and predictive factors.

AIMS/METHODS: To investigate the prevalence and risk factors for the development of diabetes mellitus after orthotopic liver transplantation, we reviewed 27 variables (including previous history of diabetes mellitus, data related to pre-transplant liver disease, and postoperative events) in 102 patients who survived longer than 1 year after orthotopic liver transplantation. RESULTS: Fourteen patients had diabetes mellitus prior to liver transplantation and all but one were alive 2 and 3 years after transplantation, with all survivors continuing to have diabetes mellitus 1, 2 and 3 years after transplantation. Among the 88 patients without pre-transplant diabetes mellitus, the prevalence of post-transplant diabetes mellitus was 27% at 1 year, 9% at 2 years and 7% at 3 years, probably related to a significant reduction in the daily prednisone dose (13 +/- 4 mg at 1 year, 7 +/- 6 mg at 2 years and 2 +/- 4 mg at 3 years, p < 0.001). Patients with post-transplant diabetes mellitus 1 year after transplantation had a higher number of rejection episodes during the first postoperative year than those without post-transplant diabetes mellitus (1.5 +/- 1.1 vs 1.1 +/- 0.7, p < 0.05) and also had higher, but not statistically significant, cumulative steroid dose and blood cyclosporine levels. Mortality of patients with post-transplant diabetes mellitus was significantly higher during the second postoperative year in comparison with patients without post-transplant diabetes mellitus: 4/24 vs 2/64 (17% vs 3%; p < 0.05). CONCLUSIONS: Liver transplantation does not significantly modify pre-transplant diabetes mellitus. Diabetes mellitus frequently develops de novo after liver transplantation, although this complication is usually transient and probably related to immunosuppressive drug administration. The prognosis of patients with post-transplant diabetes mellitus is worse than that of those without this complication.

Adult↗
PubMed1996

Taurine induces a long-lasting increase of synaptic efficacy and axon excitability in the hippocampus.

The physiological role of taurine, one of the most abundant free amino acids in the mammalian brain, is still poorly understood. We have found that bath application of the amino acid taurine induces two opposite actions on field excitatory synaptic potentials (fEPSP) recorded in the CA1 area of hippocampal slices: a decrease in fEPSP slope prevented by GABAA antagonists, and a long-lasting potentiation of fEPSP independent of GABAA or NMDA receptor activation. Two long-lasting processes account for this taurine-induced potentiation: (1) an increase in synaptic efficacy that is accompanied neither by modifications in the basic postsynaptic membrane electrical properties nor by those presynaptic changes involved in fEPSP paired-pulse facilitation; and (2) an increase in the axon excitability revealed by a reduction on the threshold for antidromic action potential activation. In addition, taurine perfusion also induces a long-lasting increase in intracellularly recorded EPSPs and monosynaptically activated IPSPs. A number of experimental observations such as temperature dependence, extracellular Na+ concentration dependence, and saturation studies, although they are not unequivocally conclusive, suggest that the taurine uptake system is required for the taurine-induced fEPSP potentiation. Our data describe a new taurine action defined as a potentiation of synaptic transmission due in part to an increment in presynaptic axon excitability and in synaptic efficacy.

Animals↗
PubMed1995

Nitrone spin traps and a nitroxide antioxidant inhibit a common pathway of thymocyte apoptosis.

Oxidative stress has recently been suggested to be a mediator of apoptotic cell death [Buttke and Sandstrom (1994) Immunology Today 15, 7-10], although evidence that this phenomenon is a widespread component of apoptosis is lacking. When rat thymocytes were exposed to the glucocorticoid methylprednisolone (MPS), a progressive increase in intracellular peroxides and a decrease in glutathione (GSH) were observed to accompany the onset of apoptosis. Using Percoll density gradients to isolate subpopulations of thymocytes at different stages of apoptosis, the increase in peroxide content was found to be restricted to apoptotic cells, while a significant depletion of GSH and reduced protein thiol was detected in both pre-apoptotic and fully apoptotic cells. To investigate the biological significance of these redox changes, the free radical spin traps 5,5-dimethyl-1-pyrroline-1-oxide (DMPO) and 3,3,5,5-tetramethyl-1-pyrroline-1-oxide (TMPO), and the related nitroxide-radical antioxidant 2,2,6,6-tetramethyl-1-piperidinyl-1-oxyl (TEMPO) were tested as inhibitors of thymocyte apoptosis. The cell shrinkage and DNA fragmentation induced by four different initiators of apoptosis were reduced by each compound. TEMPO inhibition of both etoposide- and MPS-induced thymocyte DNA fragmentation was also found to correlate with an increase in intracellular GSH, providing support for the proposal that its antioxidant properties were responsible for the observed protective activity. We conclude that some form of intracellular oxidation (here measured indirectly by changes in intracellular GSH and peroxide levels) is required during thymocyte apoptosis even when this process is initiated by an agent that does not exert a direct oxidant action.

Animals↗
PubMed1995

Antioxidant inhibition of thymocyte apoptosis by dihydrolipoic acid.

Recent findings suggest that intracellular oxidants are involved in the induction of apoptosis, and that this type of cell death can be inhibited by various thiol-containing antioxidants such as N-acetyl cysteine. To study the effects of a physiologically important thiol reductant, rat thymocytes were preincubated with either lipoic acid, dihydrolipoic acid, or lipoamide and then exposed to methylprednisolone or etoposide, two stimuli known to induce apoptosis in these cells. Dihydrolipoic acid and lipoamide both exerted an inhibitory effect on apoptosis induced by the two stimuli, while lipoic acid was inactive. Inhibition of apoptosis was evident as (a) reduced formation of condensed, pyknotic nuclei; (b) a prevention of cell shrinkage; and (c) decreased chromatin degradation. Furthermore, the depletion of reduced glutathione that occurs as thymocytes undergo apoptosis was also prevented in the presence of DHLA. Investigation of the pattern of chromatin fragmentation revealed that DNA in the antioxidant-loaded thymocytes remained above 50 kb pairs in size, indicating that inhibition by DHLA was operative at an early step in the apoptotic pathway. These results suggest that intracellular oxidation is an obligate, early component of thymocyte apoptosis.

Animals↗