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Biomedical subjects

I García

Publications and source records attributed to I García.

At least 91 records · Page 5Linked to original sources
PubMed1998

Antioxidant and anti-inflammatory properties of C-phycocyanin from blue-green algae.

OBJECTIVE: Phycocyanin is a pigment found in blue-green algae which contains open chain tetrapyrroles with possible scavenging properties. We have studied its antioxidant properties. MATERIALS AND METHODS: Phycocyanin was evaluated as a putative antioxidant in vitro by using: a) luminol-enhanced chemiluminescence (LCL) generated by three different radical species (O2-, OH., RO.) and by zymosan activated human polymorphonuclear leukocytes (PMNLs), b) deoxyribose assay and c) inhibition of liver microsomal lipid peroxidation induced by Fe+2-ascorbic acid. The antioxidant activity was also assayed in vivo in glucose oxidase (GO)-induced inflammation in mouse paw. RESULTS: The results indicated that phycocyanin is able to scavenge OH. (IC50 = 0.91 mg/mL) and RO. (IC50 = 76 microg/mL) radicals, with activity equivalent to 0.125 mg/mL of dimethyl sulphoxide (DMSO) and 0.038 microg/mL of trolox, specific scavengers of those radicals respectively. In the deoxyribose assay the second-order rate constant was 3.56 x 10(11) M(-1) S(-1), similar to that obtained for some non-steroidal anti-inflammatory drugs. Phycocyanin also inhibits liver microsomal lipid peroxidation (IC50 = 12 mg/mL), the CL response of PMNLs (p < 0.05) as well as the edema index in GO-induced inflammation in mouse paw (p < 0.05). CONCLUSIONS: To our knowledge this is the first report of the antioxidant and anti-inflammatory properties of c-phycocyanin.

Animals↗
PubMed1998

Hilar biliary cysts in hepatic transplantation. Report of three symptomatic cases and occurrence in resected liver grafts.

Hilar cysts are infrequent post-transplant biliary tract complications. Thirteen cases were discovered among 493 consecutive liver transplants (2.6%). Three (0.60%) were symptomatic (obstructive jaundice) while the other ten were found by systematically searching in the hilum in a series of 129 consecutive, resected grafts at retransplantation or autopsy (n = 54). Two types of cysts were detected: in eight grafts (1.6%), these were blind unilocular cavities with viscid mucous content, located adjacent to the biliary tract anastomoses. These had been inadvertently created as a result of the sequestered remnant cystic duct after cholecystectomies and biliary tract reconstructions, where a double-barreled common duct and long cystic duct had been present in the donor liver. These mucoceles ranged from 0.5 to 5.5 cm in diameter (median 1.7 cm). The three symptomatic cases were diagnosed by imaging techniques 3.5 years after transplantation; however, this type of cyst was found as early as the 2nd month post-transplantation when detected in lost liver grafts. Five livers (1%), lost between 5 months and 2.8 years post-transplantation, showed cystically dilated peribiliary glands, sometimes with multilocular, and occasionally multiple, cavities ranging from 0.5 to 2 cm in diameter (median 0.8 cm). This type of cyst was asymptomatic and located adjacent to the left, right, or common hepatic ducts. Threads were found near four cysts, suggesting that surgical injury may have been responsible for obstructing the neck of the glands. With the increasing number of long-term survivors of liver transplantation, unless preventive surgical methods are implemented, the number of symptomatic cysts of these origins can be expected to grow. Transplantation teams should, therefore, be aware of these potential causes of biliary tract complications.

Adolescent↗
PubMed1998

Steroid withdrawal is safe and beneficial in stable cyclosporine-treated liver transplant patients.

BACKGROUND: In the immunosuppression of orthotopic liver transplant recipients, steroids are used despite their unspecific action and long-term side effects. Few studies have been carried out on steroid withdrawal and many aspects remain to be elucidated. METHODS: A prospective study was performed to analyse the effect of steroid withdrawal on 86 patients with stable graft function, more than 1 year after orthotopic liver transplant. Thirty patients had chronic hepatitis in the graft. Seventy-two continued with cyclosporine (CsA) and 14 with CsA-azathioprine (AZA) therapy. The follow-up was 23.2 +/- 8.1 months (range 12-52 months). A paired t-test was used for statistical analysis. RESULTS: No acute or chronic rejection occurred, and steroids were not reinstituted. There were no changes in serum transaminase levels, but bilirubin levels decreased (p < 0.01). At the end of the follow-up, we found improvements in blood pressure in hypertensive patients (systolic 156.1 +/- 8.4 mmHg vs. 139.4 +/- 8.7 mmHg, p < 0.001); body weight (72 +/- 13.5 kg vs. 70.8 +/- 13 kg, p < 0.05); serum cholesterol (211.3 +/- 42 mg/dl vs. 191.6 +/- 43.5 mg/dl, p < 0.001) and bone mineral density in lumbar spine (0.823 +/- 0.13 g/cm2 vs. 0.893 +/- 0.135 g/cm2, p < 0.001). Four of ten diabetic patients were no longer insulin-dependent and insulin requirements decreased in the remaining six. No significant biochemical changes were found in patients with hepatitis in the graft, and we found an improvement in inflammatory activity in the nine biopsied patients. CONCLUSIONS: Steroid withdrawal with CsA monotherapy is feasible, safe and beneficial in patients who have stable liver graft function 1 year after orthotopic liver transplant. We consider that AZA therapy is not necessary unless drastic reduction of CsA levels is required because of renal dysfunction.

Adult↗
PubMed1998

G proteins are involved in the suppression of collagen alpha 1 (I) gene expression in cultured rat hepatic stellate cells.

We analyse the role of the G proteins in regulating collagen gene expression by measuring collagen alpha 1(I) mRNA levels in cultured hepatic stellate cells in basal conditions and after stimulating or inhibiting the major intracellular signalling pathways. Stimulation of Gs protein and adenylyl cyclase or the addition of 8Br-cAMP to the cells led to a decrease in collagen alpha 1(I) mRNA levels, while blocking protein kinase A abolished this effect. Blocking Gi protein, phospholipase A2 and C, calcium channels and calmodulin resulted in a significant increase in collagen mRNA levels. PKC stimulation led to a marked decrease in these levels. These results suggest that collagen gene expression is inhibited by a number of intracellular pathways. A Gs and a pertussis toxin-sensitive G protein seem to initiate cellular response. Transcription factors, acting in these pathways, must be identified. However, it seems that they do not need to be synthesised.

Adenylyl Cyclases↗
PubMed1998

Energy-dependent accumulation of fluoroquinolones in quinolone-resistant Klebsiella pneumoniae strains.

The intracellular accumulation of norfloxacin and pefloxacin in Klebsiella pneumoniae was evaluated. The roles of lipopolysaccharide, capsule, and outer membrane proteins were not important for the intrabacterial accumulation of fluoroquinolones in isogenic strains with known outer membrane alterations. In fluoroquinolone-resistant clinical isolates also expressing GyrA alterations, an active efflux leading to decreased accumulation of the drugs enhanced their resistance to these agents.

Anti-Infective Agents↗
PubMed1998

[Laparoscopic feeding gastrostomy: an alternative to the nasogastric tube].

Dysphagia is common in head and neck cancer and feeding becomes difficult. Nasogastric tubes cannot by placed in some patients and are poorly tolerated in others. However, endoscopic laparotomy techniques have advanced to a point in which they allow feeding gastrostomies to be used, which are non-aggressive, well-tolerated and a satisfactory alternative for patients with contraindications for upper endoscopy.

Deglutition Disorders↗
PubMed1998

[Opsonin requirements for phagocytosis of Enterococcus spp. by human polymorphonuclear leukocytes].

BACKGROUND: Interaction of Enterococcus spp. and host defense mechanisms is not well known. Opsonic requirements of Enterococcus faecalis and Enterococcus faecium to be phagocyted by human polymorphonuclear leukocytes (PMN) were evaluated. METHODS: Twenty strains (10 E. faecalis and 10 E. faecium) were studied. Phagocytosis was determined by a radiometric assay. Bacterial cells were labelled with 3H-adenine and opsonized with: a) 10% of human pool sera (HPS); b) 10% of decomplemented HPS, and c) albumin and fibronectin. RESULTS: Phagocytosis of Enterococcus spp. by PMN in the presence of HPS was significantly higher than that in the absence of opsonins. The phagocytosis of E. faecium was higher than that of E. faecalis. A strain-dependent effect of complement in the phagocytosis of Enterococcus spp. was observed. Neither albumin nor fibronectin showed an opsonic activity on Enterococcus spp. CONCLUSIONS: A great heterogeneity in the opsonic requirements of Enterococcus spp. was observed. Serum opsonins show a critical role in the phagocytosis of E. faecalis and E. faecium by PMN, this effect being more relevant with E. faecium. A strain-dependent opsonic activity of complement was observed.

Adult↗
PubMed1997

Tumor necrosis factor-alpha increases ATP content in metabolically inhibited L929 cells preceding cell death.

The effects of tumor necrosis factor-alpha (TNF) on ATP levels were studied in metabolically inhibited L929 cells. Treatment of these cells with TNF in the presence of actinomycin D or cycloheximide induces cyclic changes in the intracellular ATP content preceding cell death. After 3 h of incubation, the intracellular ATP content increased by 48 +/- 6% (p < 0.001), but at 4 h, it decreased to the control level. Two hours later, it increased again by 23 +/- 5% over the control level (p < 0.001). Coinciding with cell death, ATP content decreased progressively until almost complete depletion. These changes in ATP content were associated with parallel alterations in the respiratory coupling and with increased generation of reactive oxygen species. The mechanism by which TNF/actinomycin D or TNF/cycloheximide increased cellular ATP seemed to be dependent on the mitochondrial ATP synthesis and related to the cytotoxic effect of TNF, since blockade of mitochondrial electron transport prevented the increase in cellular ATP, the formation of reactive oxygen species, and the apoptotic cell death caused by TNF. We suggest that the TNF/actinomycin D- or TNF/cycloheximide-induced changes in intracellular ATP levels may be involved in the cytotoxic effect of TNF in metabolically inhibited L929 cells.

Adenosine Diphosphate↗
PubMed1997

p53 expression is of independent predictive value in lymph node-negative breast carcinoma.

The aim of this study was to evaluate p53 expression, determined by immunohistochemistry, in 151 infiltrating ductal breast carcinomas with negative axillary lymph nodes, and to determine whether p53 can be considered as an independent prognostic value for overall and disease-free survival. A monoclonal antibody (DO-7) that reacts with an epitope on the N terminal portion of the human protein p53 was used to detect p53 in paraffin-embedded sections, utilising a standard avidin-biotin-peroxidase complex (ABC) technique with a microwave oven antigen retrieval. Overexpression of p53 (more than 50% of stained cells) was found in 45 cases (30%). Forty-five cases were negative and occasionally or moderately stained cells were present in 61 cases. p53 protein overexpression was significantly associated with high histological grade and tumour necrosis, high MIB-1 value (MIB-1 > 30%) and negative oestrogen receptor status. Univariate analysis (log-rank) showed a shorter overall survival (P = 0.003) in patients with high tumour p53 positivity. This statistical significance was also seen on multivariate analysis (Cox's logistic regression, P = 0.004). p53 protein overexpression is an independent prognostic marker in node-negative breast carcinoma for overall survival and should be used with other prognostic factors.

Adult↗
PubMed1997

Tumor necrosis factor alpha inhibits collagen alpha 1(I) gene expression in rat hepatic stellate cells through a G protein.

BACKGROUND & AIMS: Tumor necrosis factor alpha (TNF-alpha) inhibits collagen gene expression in cultured fibroblasts. By binding to cell surface receptors, TNF-alpha promotes signals within the cells. The purpose of this study was to investigate the role played by G proteins in TNF-alpha-induced inhibition of collagen gene expression. METHODS: Effect of TNF-alpha on collagen alpha 1(I) messenger RNA (mRNA) level was measured in cultured hepatic stellate cells in basal condition and after inhibiting or activating G proteins or the major intracellular signal transduction pathways. RESULTS: TNF-alpha significantly decreased the level of alpha 1(I) collagen mRNA. Treatment of cells with pertussis toxin inhibited this effect, whereas blocking adenylate cyclase or protein kinase A had no effect. Likewise, blocking phospholipase A2, phospholipase C1 calcium channels, calmodulin, or protein kinase C did not eliminate the inhibitory effect of TNF-alpha on collagen mRNA. On the other hand, C2-ceramide and sphingomyelinase reproduced the effect of TNF-alpha on collagen gene expression, and TNF-alpha did not increase the effect of sphingomyelinase. CONCLUSIONS: TNF-alpha-induced inhibition of alpha 1(I) collagen gene expression in a hepatic stellate cell line may be mediated by a pertussis toxin-sensitive G protein. TNF-alpha may inhibit this gene by using sphingomyelin/ceramide as an intracellular signal transduction pathway.

Adenylate Cyclase Toxin↗