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Biomedical subjects

G Castro

Publications and source records attributed to G Castro.

At least 19 recordsLinked to original sources
PubMed2005

Killed but metabolically active microbes: a new vaccine paradigm for eliciting effector T-cell responses and protective immunity.

We developed a new class of vaccines, based on killed but metabolically active (KBMA) bacteria, that simultaneously takes advantage of the potency of live vaccines and the safety of killed vaccines. We removed genes required for nucleotide excision repair (uvrAB), rendering microbial-based vaccines exquisitely sensitive to photochemical inactivation with psoralen and long-wavelength ultraviolet light. Colony formation of the nucleotide excision repair mutants was blocked by infrequent, randomly distributed psoralen crosslinks, but the bacterial population was able to express its genes, synthesize and secrete proteins. Using the intracellular pathogen Listeria monocytogenes as a model platform, recombinant psoralen-inactivated Lm DeltauvrAB vaccines induced potent CD4(+) and CD8(+) T-cell responses and protected mice against virus challenge in an infectious disease model and provided therapeutic benefit in a mouse cancer model. Microbial KBMA vaccines used either as a recombinant vaccine platform or as a modified form of the pathogen itself may have broad use for the treatment of infectious disease and cancer.

Animals↗
PubMed2004

HDL metabolic activities in a boy with lipoprotein lipase deficiency and his family.

BACKGROUND: Lipoprotein lipase (LPL) deficiency is a rare autosomal recessively inherited disease characterized by elevated triglyceride, low total cholesterol and quantitative and qualitative alterations of high-density lipoprotein (HDL). The aim of the present study was to explore HDL metabolic activities in a patient with LPL deficiency and in his family (n = 11). MATERIALS AND METHODS: Subjects were divided into four groups: proband (Ser447Stop/Arg170Leu carrier), Ser447Stop carriers, Arg170Leu carriers and silent mutation/wild-type carriers (controls). Cholesterol efflux from Fu5AH cells, lecithin:cholesterol acyltransferase (LCAT), cholesteryl ester transfer protein (CETP), paraoxonase 1 (PON1) and platelet-activating factor acetylhydrolase (PAF-AH) activities were evaluated. RESULTS: Comparison between the proband and the control group revealed that the boy had significantly reduced cholesterol efflux (P < 0.001), conserved LCAT activity (P > 0.05) and increased CETP activity (P < 0.001). As regards antioxidant enzymes, while PON1 activity was higher in the proband than in the controls (P < 0.0001), PAF-AH activity was reduced (P < 0.05). The other groups did not show relevant differences in comparison with controls. CONCLUSIONS: The presence of one mutation was not enough to introduce important modifications in HDL functions. Markedly reduced HDL levels can keep certain normal enzymatic activities, which probably tend to counteract the deleterious effects of LPL deficiency.

Apolipoprotein A-I↗
PubMed2003

Acception of cholesterol from cells in men of the Russian population correlates with concentration of pre-beta1 high-density lipoproteins.

We analyzed subfraction composition of HDL and cholesterol-acceptor properties of the plasma in Russian men with high and low HDL cholesterol. HDL were subfractionated by two-dimensional electrophoresis in agarose-polyacrylamide gel. The content of pre-beta1 HDL increased in individuals with high concentration of HDL cholesterol and strictly correlated with acception of cellular cholesterol in both groups.

Animals↗
PubMed2003

Prevalence of sexual dysfunction in a cohort of middle-aged women: influences of menopause and hormone replacement therapy.

In order to determine the prevalence of sexual dysfunction (SD) and related risk factors in a cohort of middle-aged women the Laumann's test (DSM-IV) was passed to 534 healthy women between 40 and 64 years old (mean: 52.4+/-5.7) attending the Southern Metropolitan Health Service in Santiago de Chile. Of all the women, 82.8% were peri- or postmenopausal, 23% had received hormone replacement therapy (HRT) and 79.2% were sexually active. Among those who were sexually active a total of 51.3% presented SD. The prevalence of SD increased with age (from 22.2% in the 40-44-year age group to 66% in the 60-64-year age group). HRT users and healthy women presented a lower risk of SD (OR: 0.1 CI: 0.0-0.1 and OR: 0.6 CI: 0.3-0.9, respectively). The risk increased after the menopause (OR: 3.3 CI: 1.6-6.9) and with age older than 49 years (OR: 3.4 CI: 1.8-6.4), hysterectomy (OR: 3.7 CI: 1.3-10.6) and when male partners presented erectile dysfunction (OR: 3.2 CI: 1.2-8.6). In conclusion sexual dysfunction affects more than 51% of middle-aged women who are sexually active and increases with age. Ovarian function and HRT significantly influence sexual activity.

Adult↗
PubMed2003

New mutations in the lipoprotein lipase gene in a young boy with chylomicronaemia syndrome and in his family.

UNLABELLED: The case is reported of a 4-y-old boy with chylomicronaemia syndrome, under treatment with a low-fat diet and medium-chain triglycerides. The clinical and biochemical characteristics of the patient and 11 members of his family were studied. Lipoprotein profile, lipoprotein lipase (LPL) mass and activity were evaluated. Nucleotide substitutions in LPL promoter and exons were screened. The proband presented with severe hypertriglyceridaemia (triglycerides = 13.25 mmol l(-1)) and non-detectable LPL activity and mass. The boy was a compound heterozygote for four molecular defects in the LPL gene, two of which have not been reported before (CGT764 CTT/Arg170 --> Leu; GGA1482 --> GGT/Gly409 --> Gly). Among the family members, the proband was the only one who carried two genetic variants that modify LPL amino acid composition. CONCLUSION: The association of different alterations in the LPL gene could be a key factor in causing the severe phenotype observed. Moreover, treatment with a low-fat diet and medium-chain triglycerides failed to normalize the patient's hypertriglyceridaemia.

Anemia↗
PubMed2001

Expression of human apolipoprotein A-I/C-III/A-IV gene cluster in mice reduces atherogenesis in response to a high fat-high cholesterol diet.

We have previously generated transgenic (Tg) mice expressing the human apolipoprotein (apo) A-I/C-III/A-IV gene cluster. This expression induced hyperlipidemia but reduced atherosclerotic lesions in genetically modified mice lacking apoE. Atherosclerosis is a multifactorial process and environmental factors such as diet play significant roles in its development. We examined here how an atherogenic diet influences the expression of the human genes and the characteristics of the Tg mice. Our results indicate that a high fat-high cholesterol diet up-regulates the intestinal expression of the three genes and the concentration of the three proteins in plasma. Cholesterol concentration was highly increased in the non-high density lipoprotein (HDL) fraction, and less, although significantly, in the HDL fraction. Tgs showed a 65% reduction in diet-induced aortic lesions compared with non-Tg mice. Atherogenic diet increases the expression of the genes encoding the scavenger receptor class B type I (SR-BI) and ATP binding cassette transporter 1 (ABCA1) proteins. As cholesterol efflux mediated by SR-BI or by ABCA1 was enhanced in Tg mice fed an atherogenic diet, we can hypothesize that increased reverse cholesterol transport is the basis of the protective mechanism observed in these animals. In conclusion, we present evidence that the expression of the human gene cluster in mice protects against atherogenesis in response to an atherogenic diet.

ATP Binding Cassette Transporter 1↗
PubMed2001

Induction of the phospholipid transfer protein gene accounts for the high density lipoprotein enlargement in mice treated with fenofibrate.

Fibrate treatment in mice is known to modulate high density lipoprotein (HDL) metabolism by regulating apolipoprotein (apo)AI and apoAII gene expression. In addition to alterations in plasma HDL levels, fibrates induce the emergence of large, cholesteryl ester-rich HDL in treated transgenic mice expressing human apoAI (HuAITg). The mechanisms of these changes may not be restricted to the modulation of apolipoprotein gene expression, and the aim of the present study was to determine whether the expression of factors known to affect HDL metabolism (i.e. phospholipid transfer protein (PLTP), lecithin:cholesterol acyltransferase, and hepatic lipase) are modified in fenofibrate-treated mice. Significant rises in plasma PLTP activity were observed after 2 weeks of fenofibrate treatment in both wild-type and HuAITg mice. Simultaneously, hepatic PLTP mRNA levels increased in a dose-dependent fashion. In contrast to PLTP, lecithin:cholesterol acyltransferase mRNA levels in HuAITg mice were not significantly modified by fenofibrate despite a significant decrease in plasma cholesterol esterification activity. Fenofibrate did not induce any change in hepatic lipase activity. Fenofibrate significantly increased HDL size, an effect that was more pronounced in HuAITg mice than in wild-type mice. This effect in wild-type mice was completely abolished in PLTP-deficient mice. Finally, fenofibrate treatment did not influence PLTP activity or hepatic mRNA in peroxisome proliferator-activated receptor-alpha-deficient mice. It is concluded that 1) fenofibrate treatment increases plasma phospholipid transfer activity as the result of up-regulation of PLTP gene expression through a peroxisome proliferator-activated receptor-alpha-dependent mechanism, and 2) increased plasma PLTP levels account for the marked enlargement of HDL in fenofibrate-treated mice.

Animals↗
PubMed2001

Cholesterol efflux capacity in vitro predicts the severity and extent of coronary artery disease in patients with and without type 2 diabetes.

OBJECTIVE: To investigate the relation between severity and extent of coronary artery disease (CAD) and in vitro cholesterol efflux capacity. DESIGN: This study consisted of 46 type 2 diabetic, and 42 nondiabetic men undergoing coronary angiography. Quantitative coronary angiography was used to estimate the severity, extent, and overall "atheroma burden" of CAD. The capacity of patient plasma to induce cholesterol efflux from cultured Fu5AH rat hepatoma cells was measured in vitro. RESULTS: In the combined study population (n = 88), there was a significant inverse correlation between efflux and global atheroma burden (r = -0.23, p < 0.05). In the diabetic group, the global atheroma burden index was independently associated both with cholesterol efflux and with LpA-I levels. However, in the nondiabetic CAD group this association was lost when efflux and LpA-I levels were included in the same model. CONCLUSION: The present study demonstrated that efflux capacity was inversely associated with the severity and extent of CAD. In the diabetic group this association was independent of LpA-I levels, suggesting impaired antiatherogenic potential of these particles in type 2 diabetic patients.

Aged↗
PubMed2001

Down-regulation of inducible nitric-oxide synthase (NOS-2) during parasite-induced gut inflammation: a path to identify a selective NOS-2 inhibitor.

Nitric oxide (NO) possesses potent anti-inflammatory properties; however, an over-production of NO will promote inflammation and induce cell and tissue dysfunction. Thus, the ability to precisely regulate NO production could prove beneficial in controlling damage. In this study, advantage was taken of the well characterized inflammatory response caused by an intestinal parasite, Trichinella spiralis, to study the relationship between intestinal inflammation and the regulation of nitric oxide synthase-type 2 (NOS-2) expression. Our study revealed that a specific gut inflammatory reaction results in inhibition of NOS-2 expression. Characteristics of this inhibition are: 1) local jejunal inflammation induced by T. spiralis systemically inhibits NOS-2 gene transcription, protein expression, and enzyme activity; 2) the inhibition blunts endotoxin-stimulated NOS-2 expression; 3) the inhibition does not extend to the expression of other isoforms of NOS, to paxillin, a housekeeper protein, or to cyclooxygenase-2, another protein induced by proinflammatory cytokines; 4) the inhibition is unlikely related to the formation of specific anti-parasite antibodies; and 5) the inhibition may involve substances other than stress-induced corticosteroids. Elucidation of such potent endogenous NOS-2 down-regulatory mechanisms could lead to the development of new strategies for the therapy of inflammatory conditions characterized by the overproduction of NO.

Animals↗
PubMed2001

Exocrine pancreatic insufficiency in tropical sprue.

BACKGROUND: Pancreatic insufficiency may appear secondary to several intestinal disorders. It may contribute to malabsorption in tropical sprue (TS). METHODS: The exocrine pancreatic function was evaluated with the indirect pancreolauryl test (PT) in 56 patients with TS. The PT results were analyzed and correlated with serum albumin levels, degree of intestinal atrophy, and steatorrhea. RESULTS: Abnormally low values were found in 36 (64.2%) cases. A significant relationship was not observed between PT and hypoalbuminemia. Patients with more severe damage by intestinal biopsy tended to have lower PT values. No relationship was found between pancreatic insufficiency and steatorrhea (expressed as g/24 h), but patients with pancreatic insufficiency had increased stool fat concentrations (expressed as percentage of wet stool weight). All patients responded favorably to treatment with folic acid and tetracycline. Fifteen patients with abnormal initial PT values underwent a repeat PT after a 6-week therapy; all of them showed normalization of PT values. CONCLUSIONS: The abnormal exocrine pancreatic function found with an indirect test in patients with TS is probably secondary to a low pancreatic hormonal stimulation due to intestinal damage, as occurs in celiac sprue. These abnormalities are reversible after specific treatment for TS.

Adolescent↗
PubMed2001

Increased levels of high-density lipoprotein cholesterol are ineffective in inhibiting the development of immune responses to oxidized low-density lipoprotein and atherosclerosis in transgenic rabbits expressing human apolipoprotein (apo) A-I with severe hypercholesterolaemia.

High levels of high-density lipoprotein (HDL) cholesterol have been reported to protect against the development of atherosclerosis in humans by increasing reverse cholesterol transport and inhibiting the oxidation of low-density lipoprotein (LDL) due to the paraoxonase content of HDL. The purpose of the present study was to assess if there are any relationships between in vivo increases in serum levels of immunological LDL oxidation markers [autoantibodies against oxidized LDL, autoantibodies against malondialdehyde-modified LDL, LDL immune complexes and anti-cardiolipin autoantibodies], paraoxonase activity and the development of atherosclerosis in control rabbits and in transgenic rabbits expressing human apolipoprotein (apo) A-I. A total of 13 apo A-I transgenic rabbits and 18 non-transgenic littermates were fed on a cholesterol-rich diet (0.4%, w/w) for 14 weeks, and were monitored at weeks 0, 2, 6, 10 and 14. Aortic atherosclerotic lesions were measured at the end of this period. Human apo A-I transgenic rabbits with high HDL cholesterol levels were not protected against the development of atherosclerosis when they were fed on a cholesterol-rich diet which induced dramatic hypercholesterolaemia. Immunological markers of LDL oxidation increased and serum paraoxonase activity decreased similarly in control and transgenic rabbits. In conclusion, the present study demonstrates that high HDL cholesterol levels are ineffective in inhibiting increases in immunological markers of LDL oxidation and the development of atherosclerosis in a mammal with severe hypercholesterolaemia.

Animals↗
PubMed2001

An integrated anaerobic--physico-chemical treatment concept for wool scouring wastewater.

The strong flow wastewater from a wool scouring industry is treated by a combination of anaerobic digestion and physico-chemical postreatment. Based on previous laboratory results (Gutiérrez et al., 1999), three anaerobic baffled reactors (ABR) of 300 m3 each were built, processing 60% of the strong flow of a wool scouring mill for about two years. COD and grease removal in the anaerobic reactors were 47-50% and 50-55% respectively, with an organic load between 8.9 and 6.7 kg COD/m3 d. The effluent of the anaerobic reactors was assayed with additives in an industrial decanter centrifuge. As results of these assays, all the effluent of the three reactors was sent to the decanter centrifuge after dosing additives. Overall COD and grease removal of the integrated system were 87% and 93% respectively. Dosage of coagulation-flocculation additives was optimized in a continuous flocculation device. The proposed treatment is cheaper and easier to control than others alternatives with COD removal higher than 93%.

Animals↗
PubMed2000

Paraoxonase activity is reduced by a pro-atherosclerotic diet in rabbits.

Serum paraoxonase (PON1) is believed to protect against the development of atherosclerosis because of its ability to retard the oxidation of low-density lipoprotein (LDL) by hydrolysing LDL-associated phospholipid and cholesteryl-ester hydroperoxides. We have examined the relationship between PON1 and atherosclerosis development in transgenic rabbits overexpressing human apolipoprotein (apo) A-I and nontransgenic littermates fed a pro-atherogenic diet. PON1 activity was higher in transgenic (4006.1 +/- 716.7 nmol/min/ml) compared to control (3078.5 +/- 623.3 nmol/min/ml) rabbits (P < 0.01) while high-density lipoprotein (HDL) cholesterol was 1.84 +/- 0.54 mmol/L in transgenic rabbits and 0.57 +/- 0.21 mmol/L in control rabbits (P = 0.0001). After feeding rabbits a high-cholesterol diet for 14 weeks HDL-cholesterol fell by 70% in both transgenic and control rabbits (P < 0.001 compared to week 0) PON1 activity fell by 50% in both groups of rabbits (P < 0. 01 compared to week 0). The amount of thoracic aortic surface area covered by lesions was 29 +/- 16% in the control group and 26 +/- 15% in the transgenic group (P = NS). A pro-atherosclerotic diet reduces PON1 which may exaggerate the effects of the diet on the development of atherosclerosis.

Animals↗
PubMed2000

Expression of human apolipoprotein A-I/C-III/A-IV gene cluster in mice induces hyperlipidemia but reduces atherogenesis.

The apolipoprotein (apo)A-I/C-III/A-IV gene cluster is involved in lipid metabolism and atherosclerosis. Overexpression of apoC-III in mice causes hypertriglyceridemia and induces atherogenesis, whereas overexpression of apoA-I or apoA-IV increases cholesterol in plasma high density lipoprotein (HDL) and protects against atherosclerosis. Each gene has been studied alone in transgenic mice but not in combination as the entire cluster. To determine which phenotype is produced by the expression of the entire gene cluster, transgenic mice were generated with a 33-kb human DNA fragment. The results showed that the transgene contained the necessary elements to direct hepatic and intestinal expression of the 3 genes. In the pooled data, plasma concentrations were 257+/-9, 7.1+/-0.5, and 1.0+/-0.2 mg/dL for human apoA-I, apoC-III, and apoA-IV, respectively (mean+/-SEM). Concentrations of these apolipoproteins were higher in males than in females. Human apoA-I and apoC-III concentrations were positively correlated, suggesting that they are coregulated. Transgenic mice exhibited gross hypertriglyceridemia and accumulation of apoB(48)-containing triglyceride-rich lipoproteins. Plasma triglyceride and cholesterol concentrations were correlated positively with human apoC-III concentration, and HDL cholesterol was correlated with apoA-I concentration. In an apoE-deficient background, despite being markedly hypertriglyceridemic, cluster transgenic animals compared with nontransgenic animals showed a 61% reduction in atherosclerosis. This suggests that apoA-I and/or apoA-IV can protect against atherosclerosis even in the presence of severe hyperlipidemia. These mice provide a new model for studies of the regulation of the 3 human genes in combination.

Animals↗
PubMed2000

Decreased susceptibility to diet-induced atherosclerosis in human apolipoprotein A-II transgenic mice.

Studies performed in vivo have been controversial regarding the implication of human apolipoprotein (apo)A-II in the atherogenic process. Expression of human apoA-II in transgenic mice fed a chow diet leads to (1) a bimodal distribution of high density lipoprotein (HDL) size as in humans, (2) a reduction in total cholesterol concentration that is mainly due to a reduction in non-HDL cholesterol level, and (3) a dramatic reduction in mouse endogenous apoA-I and apoA-II. After 20 weeks on an atherogenic diet, transgenic mice had reduced total cholesterol concentrations because of a reduction in cholesterol associated with all lipoprotein classes. Endogenous apoA-I and apoA-II were also dramatically decreased in transgenic mice. The mean area of atherosclerotic lesions was drastically decreased in transgenic mice (-44%, P=0.0027) compared with control mice. The amount of aortic surface covered by lesions was positively correlated with very low density lipoprotein cholesterol (P<0.01) and intermediate density lipoprotein cholesterol levels (P<0.05). Transgenic mice were protected against the development of atherosclerosis despite a marked decrease in HDL cholesterol and apoA-I concentrations. This protection may be related to the marked reduction in circulating low density lipoprotein (very low density and intermediate density lipoprotein) levels in transgenic mice.

Animal Nutritional Physiological Phenomena↗
PubMed2000

Complete atherosclerosis regression after human ApoE gene transfer in ApoE-deficient/nude mice.

The apolipoprotein E (apoE)-deficient mouse is a relevant animal model of human atherosclerosis. Although the prevention of atherosclerosis development has been documented after somatic gene transfer into animal models, regression of lesions remains to be demonstrated. Thus, we used this genetically defined mouse model nn the nude background to show atherosclerosis regression. ApoE-deficient nude mice were infected with 5 x 10(8) or 10(9) plaque-forming units of a first-generation adenovirus encoding human apoE cDNA. The secretion of human apoE resulted in a rapid decrease of total cholesterol, which normalized the hypercholesterolemic phenotype within 14 days (from 600+/-100 to <100 microg/mL). Transgene expression was observed during a period of >4 months, with a normalization of cholesterol and triglyceride levels during 5 months. At that time, we successfully reinjected the recombinant adenovirus and observed the appearance of the human protein as well as the correction of lipoprotein phenotype. In mice killed 6 months-after the first infection, we observed a dose-dependent regression of fatty streak lesions in the aorta. We showed sustained expression of a transgene with a first-generation adenoviral vector and a correction of dyslipoproteinemia phenotype leading to lesion regression. These data demonstrate that somatic gene transfer can induce plaque regression.

Animals↗
PubMed2000

Apolipoprotein AII enrichment of HDL enhances their affinity for class B type I scavenger receptor but inhibits specific cholesteryl ester uptake.

Apolipoproteins of high density lipoprotein (HDL) and especially apolipoprotein (apo)AI and apoAII have been demonstrated as binding directly to the class B type I scavenger receptor (SR-BI), the HDL receptor that mediates selective cholesteryl ester uptake. However, the functional relevance of the binding capacity of each apolipoprotein is still unknown. The human adrenal cell line, NCI-H295R, spontaneously expresses a high level of SR-BI, the major apoAI binding protein in these cells. As previously described for murine SR-BI, free apoAI, palmitoyl-oleoyl-phosphatidylcholine (POPC)-AI, and HDL are good ligands for human SR-BI. In vitro displacement of apoAI by apoAII in HDLs or in Lp AI purified from HDL by immunoaffinity enhances their ability to compete with POPC-AI to bind to SR-BI and also enhances their direct binding capacity. The next step was to determine whether the higher affinity of apoAII for SR-BI correlated with the specific uptake of cholesteryl esters from these HDLs. Free apoAII and, to a lesser extent, free apoAI that were added to the cell medium during uptake experiments inhibited the specific uptake of [(3)H]cholesteryl esters from HDL, indicating that binding sites on cells were the same as cholesteryl ester uptake sites. In direct experiments, the uptake of [(3)H]cholesteryl esters from apoAII-enriched HDL was highly reduced compared with the uptake from native HDL. These results demonstrate that in the human adrenal cell line expressing SR-BI as the major HDL binding protein, efficient apoAII binding has an inhibitory effect on the delivery of cholesteryl esters to cells.

Adrenal Cortex Neoplasms↗