Biomedical subjects

H Molina

Publications and source records attributed to H Molina.

At least 19 recordsLinked to original sources

PubMed2005

Angiotensin II type I antagonist on oxidative stress and heat shock protein 70 (HSP 70) expression in obstructive nephropathy.

Angiotensin II, a profibrotic cytokine, plays a main role in the initiation of renal fibrogenesis at a very early stage leading to a progressive loss of renal function in unilateral ureteral obstruction (UUO). We studied the involvement of AT1 angiotensin II receptor in the physiopathology of tubulointerstitial fibrosis in UUO, focusing in the regulation of the oxidative stress state and in the HSP 70 expression, in renal tissue. UUO or control sham operation was perform to Wistar Kyoto rats after being treated with the AT1 angiotensin II receptor antagonist Losartan (10 mg/kg/day) in the drinking water for 15 days. Twenty four hours later, mRNA AT1 receptor expression was studied. Renal fibrosis was evaluated through TGFbeta expression and superoxide dismutase (SOD) activity, hydroxyl radicals, O2- and total antioxidant activity were measured by spectrophotometric assay. Immunohistochemical and Western blot analysis of HSP 70 were performed. A non-hypotensive dose of Losartan significantly down regulated the expression of AT1 receptor. Prevention of renal fibrogenesis by Losartan treatment was demonstrated by TGFbeta mRNA expression similar to control. Oxidative stress in obstructed kidney was evident since a decreased SOD activity and a two-fold increase in the concentration of hydroxyl radicals and O2- was observed when compared to the control. Losartan produced down regulation of ROS with recovery of the SOD activity and higher expression of HSP 70 compared to obstructed kidney of rats receiving vehicle. We can conclude that after 24 hr of UUO, protection against tubulointerstitial fibrosis by Losartan, independent from changes in blood pressure, includes decreased oxidative stress linked to upregulation of HSP 70 expression.

Angiotensin II Type 1 Receptor Blockers↗

PubMed2005

Total gastrectomy with or without abdominal drains. A prospective randomized trial.

The most common postoperative complications of total gastrectomy are esophagojejunal anastomotic leakage and subphrenic abscess. These complications are a cause of morbidity and mortality, relaparotomy, and longer postoperative stay. The use of abdominal drains is useful for the early diagnosis and management of anastomotic leaks. The aim of this study was to analyze our experience with total gastrectomy for gastric cancer in patients with and without abdominal drains, and to evaluate the results regarding postoperative morbidity, postoperative hospital stay, postoperative days for oral intake, relaparotomy and mortality. This prospective and randomized study examines the results in 60 consecutive patients (43 males and 17 females) with gastric cancer who underwent total gastrectomy in the Regional Clinical Hospital of Concepción, Chile, between 2000 and 2003. Patients were divided into two groups: group I (without drains) and group II (two drains). We found 31 patients in group I and 29 patients in group II. The mean length of postoperative stay was 12.9 days in group I and 18.8 days in group II (p = 0.0242, s.). Morbidity was 9.7% in group I and 37.9% in group II (p = 0.0242, s.). Re-explorations were more frequent in group II (24.1%) versus group I (9.7%) (p = 0.1239, n.s.). Postoperative days for oral intake were 9.4 in group I and 12.8 in group II (p = 0.0514, n.s.) Mortality was 0% in group I and 3.4% in group II (p = 0.4833, n.s.). In our experience, morbidity and postoperative hospital stay were statistically higher in the group of patients with abdominal drains.

Adult↗

PubMed2003

Expression and regulation of scavenger receptor class B type I (SR-BI) in gall bladder epithelium.

BACKGROUND AND AIMS: Biliary lipid absorption by the gall bladder mucosa and the cholesterol content of the gall bladder wall appear to play a role in cholesterol gall stone formation. As the scavenger receptor class B type I (SR- BI) regulates cellular cholesterol uptake, we studied its expression in human and murine gall bladders, its regulation by increased biliary lipid content, and its role in gall stone formation. METHODS AND RESULTS: Using immunohistochemistry, SR-BI was found in the apical domain of human gall bladder epithelial cells. Immunoblotting of isolated membranes from gall bladder epithelial cells showed a specific signal for the 82 kDa SR-BI protein. In C57BL/6 mice, SR-BI was also found in the gall bladder epithelium. Using western blot analysis, an inverse relationship was observed between biliary cholesterol concentration and SR-BI expression in murine gall bladder mucosa. By comparing lithogenic diet fed wild-type and SR-BI deficient mice, gall bladder wall cholesterol content and gall stone formation were not found to be dependent on SR-BI expression. CONCLUSIONS: (i) SR-BI is expressed in both human and murine gall bladder epithelium; (ii) biliary cholesterol hypersecretion is associated with decreased gall bladder SR-BI expression in mice; and (iii) murine SR-BI is not essential in controlling gall bladder wall cholesterol content and gall stone formation during diet induced cholelithiasis.

Animals↗

PubMed2002

The murine complement regulator Crry: new insights into the immunobiology of complement regulation.

Complement has an important role in inflammation and in the normal function of the immune system. Activated complement fragments have the capacity to bind and damage self-tissues. Cells from vertebrates express on their surface regulators of complement activation that protect them from the deleterious effects of cell-bound complement fragments. Abnormalities in these regulators of complement activation may participate in the pathogenesis of autoimmune diseases and inflammatory disorders. Murine Crry is one of these regulators that inhibits the activation of the third component of complement and protects self-tissues from complement-mediated damage. Experimental work on Crry has increased our understanding of the immunobiology of complement regulation and the potential role of complement and complement inhibitors in the development and treatment of human diseases.

Animals↗

PubMed2001

DNA-bound transcription factor complexes analysed by mass-spectrometry: binding of novel proteins to the human c-fos SRE and related sequences.

Transcription factors control eukaryotic polymerase II function by influencing the recruitment of multiprotein complexes to promoters and their subsequent integrated function. The complexity of the functional 'transcriptosome' has necessitated biochemical fractionation and subsequent protein sequencing on a grand scale to identify individual components. As a consequence, much is now known of the basal transcription complex. In contrast, less is known about the complexes formed at distal promoter elements. The c-fos SRE, for example, is known to bind Serum Response Factor (SRF) and ternary complex factors such as Elk-1. Their interaction with other factors at the SRE is implied but, to date, none have been identified. Here we describe the use of mass-spectrometric sequencing to identify six proteins, SRF, Elk-1 and four novel proteins, captured on SRE duplexes linked to magnetic beads. This approach is generally applicable to the characterisation of nucleic acid-bound protein complexes and the post-translational modification of their components.

Amino Acid Sequence↗

PubMed2001

Prevention of T cell-driven complement activation and inflammation by tryptophan catabolism during pregnancy.

Indoleamine 2,3 dioxygenase (IDO) activity during pregnancy protects developing fetuses from maternal immune responses in CBA mice. We show here that fetal allografts were rejected only in mating combinations where paternally inherited tissue antigens elicited potent maternal T cell responses after exposure to IDO inhibitor. IDO inhibitor treatment triggered extensive inflammation at the maternal-fetal interface in susceptible mating combinations, which was characterized by complement deposition and hemorrhagic necrosis. Identical inflammatory responses occurred in B cell-deficient (RAG-I-/-) mothers that carried a monoclonal cohort of CD8+ T cells specific for a single paternally inherited fetal major histocompatibility complex antigen. Thus, fetal allograft rejection was accompanied by a unique form of inflammation that was characterized by T cell-dependent, antibody-independent activation of complement. In contrast, no inflammation, complement deposition or T cell infiltration was elicited when mice carrying syngeneic fetuses were exposed to IDO inhibitor. These data show that IDO activity protects the fetus by suppressing T cell-driven local inflammatory responses to fetal alloantigens.

Animals↗

PubMed2001

Complement facilitates early prion pathogenesis.

New-variant Creutzfeldt-Jakob disease and scrapie are typically initiated by extracerebral exposure to the causative agent, and exhibit early prion replication in lymphoid organs. In mouse scrapie, depletion of B-lymphocytes prevents neuropathogenesis after intraperitoneal inoculation, probably due to impaired lymphotoxin-dependent maturation of follicular dendritic cells (FDCs), which are a major extracerebral prion reservoir. FDCs trap immune complexes with Fc-gamma receptors and C3d/C4b-opsonized antigens with CD21/CD35 complement receptors. We examined whether these mechanisms participate in peripheral prion pathogenesis. Depletion of circulating immunoglobulins or of individual Fc-gamma receptors had no effect on scrapie pathogenesis if B-cell maturation was unaffected. However, mice deficient in C3, C1q, Bf/C2, combinations thereof or complement receptors were partially or fully protected against spongiform encephalopathy upon intraperitoneal exposure to limiting amounts of prions. Splenic accumulation of prion infectivity and PrPSc was delayed, indicating that activation of specific complement components is involved in the initial trapping of prions in lymphoreticular organs early after infection.

Animals↗

PubMed2001

Effects of the gp130 cytokines ciliary neurotropic factor (CNTF) and interleukin-11 on pituitary cells: CNTF receptors on human pituitary adenomas and stimulation of prolactin and GH secretion in normal rat anterior pituitary aggregate cultures.

Two of the most potent cytokines regulating anterior pituitary cell function are leukemia inhibitory factor (LIF) and interleukin (IL)-6, which belong to the cytokine family using the common gp130 signal transducer. Recently, the expression and action of two other members of this family, IL-11 and ciliary neurotrophic factor (CNTF), on different cell lines has also been demonstrated. We studied the expression of the specific receptor subunits for CNTF in mammotropic, non-functioning and somatotropic tumors and the action of CNTF and IL-11 in the regulation of hormone secretion in these and normal pituitary cells. The mRNA for the alpha chain specific for the CNTF receptor was detected by Northern blot in tumors secreting prolactin (PRL) and GH and in non-functioning tumors. We found that both IL-11 and CNTF exerted a similar stimulatory effect on GH mRNA expression in somatotropic monolayer cell cultures from acromegalic tumors, but these cytokines had no significant influence on GH secretion. CNTF stimulates prolactin secretion in lactotropic monolayer cell cultures from patients with prolactinoma. In monolayer cell cultures from normal rat anterior pituitary, IL-11 and CNTF had no significant effect on the release of either GH or PRL, or on GH mRNA. However, when the cells were cultured in aggregate cultures, in which the three-dimensional structure of the cells is reconstituted, both cytokines, in doses at which they had no effect on monolayer cultures, significantly stimulated both PRL and GH secretion. These data show that IL-11 and CNTF may act as regulatory factors in anterior pituitary cells, in which the three-dimensional structure of the gland is of critical importance.

Adenoma↗

PubMed2000

Horseradish peroxidase binding to intestinal brush-border membranes of Cyprinus carpio. Identification of a putative receptor.

Morphologic studies have shown that the classic endocytosis tracer horseradish peroxidase (HRP) is actively internalized by vesicular transport in the carp intestine, suggesting the existence of specific binding sites in the apical membrane of enterocytes. The aim of the present study was to develop an in vitro binding assay using isolated carp intestinal brush-border membranes (BBM) to demonstrate and characterize these specific HRP binding sites. The results obtained show that HRP binding to BBM exhibits a saturable mode and high affinity (K(d) = 22 nM). In addition, HRP binding sites are highly enriched in BBM compared to basolateral membranes. On the other hand, HRP interaction with these sites is apparently of an ionic character because binding increased concomitantly with decreasing NaCl concentrations in the assay, reaching a maximum in the absence of NaCl. Other proteins that are also internalized in carp intestine did not significantly inhibit HRP binding to BBM. A lectin-type of interaction was discarded because neither manan nor ovoalbumin inhibited HRP binding. Proteinase K treatment of BBM reduced HRP binding by 70%, suggesting a proteic nature for this binding site. Finally, ligand blotting assays showed that HRP binds specifically to a 15.3-kDa protein. Taken together, these results are consistent with the existence of a functional receptor for HRP in carp intestinal mucosa that could mediate its internalization.

Animals↗

PubMed2000

Impaired affinity maturation in Cr2-/- mice is rescued by adjuvants without improvement in germinal center development.

Cr2-/- mice have an impairment in humoral immunity, as shown by the decrease in the Ab titers against T cell-dependent Ags and abnormalities in germinal center formation. Germinal centers are present, but they are decreased in size and number, indicating problems in their development. In this study, we investigated whether this abnormality in germinal center development is associated with problems in the establishment of optimal affinity maturation and the generation of memory B cells, processes closely related to the germinal center reaction. We immunized the Cr2-/- animals with different Ags with or without adjuvants. We showed that, when immunized without adjuvants, complement receptors are absolutely required for optimal affinity maturation. Although limited affinity maturation is elicited in the Cr2-/- Ab response, it is decreased as compared with normal animals. Memory B cell generation is also impaired. In the presence of adjuvants, germinal center development in the Cr2-/- mice is still abnormal, as demonstrated by their decreased size and number. Surprisingly, adjuvants establish optimal affinity maturation and partially restore the amount of Ab produced during the primary response and memory B cell generation. However, adjuvants cannot improve the ability of follicular dendritic cells to retain Ags in the form of immune complexes. These observations indicate that immunization with inflammatory Ags offset some of the immunological abnormalities found in the Cr2-/- mice and show that optimal affinity maturation in the Cr2-/- mice can be achieved in the absence of normal germinal centers.

Adjuvants, Immunologic↗

PubMed2000

Antibody production in mice deficient for complement receptors 1 and 2 can be induced by IgG/Ag and IgE/Ag, but not IgM/Ag complexes.

Deficiencies in C factors C2, C3, or C4 as well as lack of C receptors 1 and 2 (CR1/2) lead to impaired Ab production. Classical pathway activation plays a major role, as mice deficient in factor B, a key factor in the alternative pathway, have normal Ab production. Abs in complex with their specific Ag are known to feedback regulate the Ab response, and enhanced responses are initiated by IgM, IgE, and IgG. IgM acts via the C system, whereas IgE and IgG can operate independently of C via Fc receptors. Here we have investigated whether these isotypes are able to enhance Ab responses in mice lacking CR1/2. SRBC-specific IgM, administered with SRBC, does not enhance Ab responses in these animals. In contrast, 2,4, 6-trinitrophenyl-specific IgE and IgG2a, administered with BSA-2,4, 6-trinitrophenyl, induce potent Ab responses in CR1/2-deficient mice. Additionally, BSA administered with CFA or alum induced strong Ab responses in the absence of CR1/2. These results indicate that CR1/2 is needed to promote IgM-mediated induction of primary Ab responses. The data also show that the need for CR1/2 can be circumvented by Abs typical of a secondary immune response forming complexes with Ag or by conventional adjuvants, presumably mimicking physiological inflammatory reactions.

Adjuvants, Immunologic↗

PubMed2000

A critical role for murine complement regulator crry in fetomaternal tolerance.

Complement is a component of natural immunity. Its regulation is needed to protect tissues from inflammation, but mice with a disrupted gene for the complement regulator decay accelerating factor were normal. Mice that were deficient in another murine complement regulator, Crry, were generated to investigate its role in vivo. Survival of Crry-/- embryos was compromised because of complement deposition and concomitant placenta inflammation. Complement activation at the fetomaternal interface caused the fetal loss because breeding to C3-/- mice rescued Crry-/- mice from lethality. Thus, the regulation of complement is critical in fetal control of maternal processes that mediate tissue damage.

Animals↗

PubMed2000

Antigen persistence is required for somatic mutation and affinity maturation of immunoglobulin.

Whether germinal centers (GC) with follicular dendritic cell (FDC) clusters are the essential sites for affinity maturation of immunoglobulin is still controversial. To re-evaluate the role of GC / FDC in affinity maturation and somatic mutation in a defined antigen system, lymphotoxin-alpha(- / -) and TNF receptor I(- / -) mice, lacking GC / FDC, were immunized with (4-hydroxy-3-nitrophenyl) acetyl-sheep RBC (NP-SRBC). In contrast to soluble hapten-carrier systems, NP-SRBC allows us to compare affinity maturation in the presence or absence of adjuvant. These mice showed a dramatically impaired ability to generate high-affinity IgG to NP, but retained the ability to produce low-affinity anti-NP IgG when NP-SRBC was used in the absence of adjuvant. In contrast to wild-type mice, somatic mutation of the expressed IgG heavy chain gene was rarely detected in these GC / FDC-deficient mice. This suggests that GC / FDC are essential for affinity maturation. Trapping antigen-specific B cells inside the T cell zone of TNFRI(- / -) mice may prolong the interaction between T and B cells, which allows class switching but no further affinity maturation of IgG. Interestingly, GC / FDC-deficient mice could be induced to generate high-affinity, somatically mutated IgG antibodies by immunization with the same amount of NP-SRBC antigen emulsified in incomplete Freund's adjuvant or repeated immunization with the antigen alone. Thus, these data support a model in which prolonged availability of antigen is required for somatic mutation and affinity maturation, and FDC or adjuvants facilitate such processes by slowly releasing antigens.

Animals↗

PubMed2000

Oral folate reduces plasma homocyst(e)ine levels in hemodialysis patients with cardiovascular disease.

INTRODUCTION: Hyperhomocyst(e)inemia (plasma homocyst(e)ine concentration >16.0 micromol/l) is an independent risk factor for atherosclerosis, and is ubiquitous in patients with end-stage renal disease (ESRD). Oral folate supplementation in the non-ESRD population has been demonstrated to reduce plasma homocyst(e)ine (Hcy) concentration, and may reduce atherosclerotic morbidity. This study was undertaken to evaluate the efficacy of folate supplementation in reducing Hcy in patients with ESRD and cardiovascular disease. METHODS: Twenty-eight chronic hemodialysis patients with demonstrated hyperhomocyst(e)inemia (mean Hcy 35.2+/-13.3 micromol/l) were enrolled in the study. The presence of atherosclerosis was documented by history, physical examination, or ultrasonographic criteria. Hcy was determined initially and following six weeks' supplementation with 5.0mg folate and multvitamins. RESULTS: Hcy fell a mean of 15.0+/-10.4 micromol/l (38.9+/-19.9%) following supplementation (p<0.0005, paired t-test). In patients whose Hcy 'normalized' (n=10) Hcy fell a mean of 51+/-14% compared to a reduction of 32+/-20% in 18 patients whose Hcy remained >16.0 micromol/l (p=0.02). A significant positive correlation was observed between initial Hcy and both absolute and percent reduction after folate supplementation (r=0.87, p<0.005 and 0.53, p<0.005, respectively). Seven patients with documented atherosclerosis were older (68+/-8 yr vs 51+/-5 yr, p=0.007) an tended to have lower initial and final Hcy than the 21 patients without atherosclerosis (26.8+/-9.9 vs. 38.0+/-13.3 micromol/l, p=0.051 and 16.5+/-5.0 vs. 21.3+/-6.7, p=0.06, respectively). The presence of atherosclerosis was not associated with significant alteration in the response to folate. CONCLUSIONS: Supplementation with high-dose folate significantly reduces plasma Hcy in patients with and without atherosclerosis, and the presence of atherosclerosis does not impact on patients' response to folate and multivitamin supplementation. Hcy remained >16.0 micromol/l in the majority of patients, however, despite large absolute reductions in Hcy. Doses of folate greater than 5mg, or additional therapy may be required to further reduce Hcy in the majority of ESRD patients.

Adult↗

PubMed2000

Interleukin-6 is inhibited by glucocorticoids and stimulates ACTH secretion and POMC expression in human corticotroph pituitary adenomas.

Interleukins and their receptors are expressed intrinsically in the anterior pituitary and regulate hormone production and cell proliferation. It has previously been shown that interleukin-6 (IL-6) regulates hormone secretion in normal pituitary cells and cell lines. Here we examined the effects of IL-6 on propiomelanocortin (POMC) expression and ACTH production in corticotroph adenoma cells in vitro. We found that IL-6 stimulates both ACTH secretion and POMC gene expression in corticotroph adenoma cell cultures. This first demonstration of the stimulatory action of IL-6 on human corticotroph adenoma cell function provides further evidence for a direct action of IL-6 on corticotroph pituitary cells. We have confirmed previous reports of IL-6 production by corticotroph adenoma cells and in addition, demonstrated for the first time that the synthetic glucocorticoid dexamethasone is a potent suppressor of intratumoral IL-6 production. This intratumoral produced IL-6 may be in part responsible, in an autocrine manner, for the stimulation of ACTH synthesis and secretion. Our results suggest that IL-6 might play a role in the pathogenesis of Cushing's disease. However, elevated glucocorticoid levels in patients with Cushing's disease may prevent excessive action of IL-6 on ACTH production and tumor progression of corticotroph adenomas in vivo.

Adenoma↗

PubMed2000

Genomic organization of the serine protease light chain of mouse complement factor I gene.

A portion of the mouse complement factor I (mCFI) gene encoding for the mCFI light chain was cloned from a mouse 129/SVJ1 bacterial artificial chromosome library. It contains five exons and four introns. The intron sizes are remarkably different from the human homolog. Several polymorphisms were found in exon 13. One polymorphism was in the coding region, which causes a threonine in the Balb/c mCFI to be replaced by an isoleucine in the 129/SVJ1 mCFI. The other two polymorphisms are located in the 3' untranslated region. The organization of the serine protease domain in mCFI is similar to that of trypsin but very different from that of the other complement serine proteases.

Amino Acid Substitution↗

PubMed2000

High levels of matrix metalloproteinases regulate proliferation and hormone secretion in pituitary cells.

Beside the digestion of the extracellular matrix during tumor invasion and metastasis, more recently, new functions for matrix metalloproteinases (MMPs) have been proposed. We studied the expression and function of these enzymes in pituitary cells. We observed the activities of MMP-2 and MMP-9 together with expression of membrane-type MMP and tissue inhibitor of metalloproteinase-1 in all types of human pituitary adenomas. We found surprisingly high levels of MMP activity and low levels of tissue inhibitor of metalloproteinases, indicating a high level of extracellular matrix-degrading activity in pituitary adenomas. To examine the function of metalloproteinase activity in pituitary cells we used the synthetic MMP inhibitor batimastat. These studies demonstrate that MMPs secreted by pituitary cells can release growth factors anchored to the extracellular matrix that, in turn, control pituitary cell proliferation and hormone secretion. These results define a new additional mechanism for the control of pituitary hormone secretion and indicate new potential therapeutic targets for pituitary adenomas.

Adenoma↗

PubMed1999

Murine gammaherpesvirus 68 encodes a functional regulator of complement activation.

Sequence analysis of the murine gammaherpesvirus 68 (gammaHV68) genome revealed an open reading frame (gene 4) which is homologous to a family of proteins known as the regulators of complement activation (RCA proteins) (H. W. Virgin, P. Latreille, P. Wamsley, K. Hallsworth, K. E. Weck, A. J. Dal Canto, and S. H. Speck, J. Virol. 71:5894-5904, 1997). The predicted gene 4 product has homology to other virally encoded RCA homologs, as well as to the complement-regulatory proteins decay-accelerating factor and membrane cofactor protein. Analyses by Northern blotting and rapid amplification of cDNA ends revealed that gene 4 is transcribed as a 5.2-kb bicistronic transcript of the late kinetic class. Three gammaHV68 RCA protein isoforms (60 to 65 kDa, 50 to 55 kDa, and 40 to 45 kDa) were detected by Western blotting of infected murine NIH 3T12 fibroblast cells. A soluble 40- to 45-kDa isoform was detected in the supernatants of virally infected cells. Flow cytometric analysis revealed that the gammaHV68 RCA protein was expressed on the surfaces of infected cells. Supernatants from virally infected cells contained an activity that inhibited murine complement activation as measured by inhibition of C3 deposition on activated zymosan particles. Recombinant gammaHV68 RCA protein, containing the four conserved short consensus repeats, inhibited murine C3 deposition on zymosan via both classical and alternative pathways and inhibited deposition of human C3 on activated zymosan particles. Expression of this inhibitor of complement activation, both at the cell surface and in the fluid phase, may be important for gammaHV68 pathogenesis via the inhibition of innate and adaptive immunity.

Amino Acid Sequence↗