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H Melin-Aldana

Publications and source records attributed to H Melin-Aldana.

13 recordsLinked to original sources
PubMed2001

Plasminogen deficiency leads to impaired lobular reorganization and matrix accumulation after chronic liver injury.

To determine the regulatory role of plasminogen in hepatic repair following a chronic liver injury, we injected carbon tetrachloride (CCl(4)) biweekly into mice lacking plasminogen (Plg(0)) and plasminogen-sufficient littermates (Plg(+)). On gross examination, we found that Plg(0) livers became enlarged and pale with foci of red nodules as early as 4 weeks after CCl(4) injection, while Plg(+) livers appeared minimally affected by 6 weeks. Microscopically, Plg(0) livers had a pronounced pericentral linking, with accumulation of centrilobular eosinophilic material in injured areas, which resulted in a significant increase in liver mass and total protein. Immunohistochemistry revealed that fibrin accumulated progressively in injured regions. However, the combined genetic loss of plasminogen and fibrinogen did not correct the abnormal phenotype. Mason's trichrome staining revealed intense signal in centrilobular regions and electron microscopy showed a marked increase in fibrillary material demonstrating an excessive accumulation of extracellular matrix in Plg(0) mice. The zone-specific increase in matrix components was associated with an increase in the number of activated hepatic stellate cells within injured sites of Plg(0) livers. Taken together, these data suggest that the progressive accumulation of fibrin-unrelated matrix substrates in Plg(0) livers after a chronic injury results from the combined effects of impaired proteolysis and increased matrix production.

Afibrinogenemia↗
PubMed2001

Plasminogen activators direct reorganization of the liver lobule after acute injury.

Tissue repair requires an adequate cellular proliferation coordinated with the timely proteolysis of matrix elements. Based on the properties of plasminogen activators in liver cell proliferation and tissue proteolysis, we explored the regulatory role of tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA) in liver repair. Using carbon tetrachloride (CCl(4)) intoxication as a model of acute liver injury, we found that tPA-deficient mice displayed a mild defect in hepatic repair, whereas livers of uPA-deficient mice had a more substantial delay in repair, with injury of centrilobular hepatocytes persisting up to 14 days after CCl(4). Notably, functional cooperativity between plasminogen activators was strongly inferred from the profound reparative defect in livers of mice lacking tPA and uPA simultaneously, with persistence of centrilobular injury as far out as 35 days. The defective repair was not because of increased susceptibility of experimental mice to the toxin or to inadequate cellular proliferation. Instead, lack of plasminogen activators led to the accumulation of fibrin and fibronectin within injured areas and poor removal of necrotic cells. These data demonstrate that tPA and uPA play a critical role in hepatic repair via proteolysis of matrix elements and clearance of cellular debris from the field of injury.

Acute Disease↗
PubMed2001

Plasminogen deficiency results in poor clearance of non-fibrin matrix and persistent activation of hepatic stellate cells after an acute injury.

BACKGROUND/AIMS: Plasminogen directs matrix proteolysis during liver repair. Based on the role of hepatic stellate cells (HSCs) on matrix production, we investigated whether plasminogen-driven matrix proteolysis modulates the phenotype of HSCs. METHODS: Carbon tetrachloride was injected intraperitoneally into mice deficient in plasminogen, fibrinogen, or both, and to normal littermates, followed by determination of the phenotype of HSCs, matrix deposition, and apoptosis. RESULTS: Activation of HSCs was restricted to the zone of injury and increased >ten-fold above baseline regardless of the plasminogen status 2 days after toxin. Thereafter, the number of activated HSCs decreased to baseline levels between 7 and 14 days in normal mice, but remained elevated in plasminogen-deficient livers approximately ten-fold above non-targeted littermates. Despite the zonal increase in activated HSCs, the total number of desmin-stained HSCs was similar along the lobule in both genotypes. No appreciable difference in apoptosis of perisinusoidal cells was found between genotypes; however, fibrillary material was present in the subsinusoidal space of Plg(0) livers. This fibrillary material was not fibrin, as demonstrated by similar findings in Plg(0)/Fib(0) mice, which accumulated fibronectin in injured areas. CONCLUSIONS: Proteolytic clearance of non-fibrin matrix components by plasminogen must occur for HSCs to restore the quiescent phenotype during liver repair.

Animals↗
PubMed1999

Plasminogen deficiency leads to impaired remodeling after a toxic injury to the liver.

Cellular proliferation and tissue remodeling are central to the regenerative response after a toxic injury to the liver. To explore the role of plasminogen in hepatic tissue remodeling and regeneration, we used carbon tetrachloride to induce an acute liver injury in plasminogen-deficient (Plg(o)) mice and nontransgenic littermates (Plg(+)). On day 2 after CCl(4), livers of Plg(+) and Plg(o) mice had a similar diseased pale/lacy appearance, followed by restoration of normal appearance in Plg(+) livers by day 7. In contrast, Plg(o) livers remained diseased for as long as 2.5 months, with a diffuse pale/lacy appearance and persistent damage to centrilobular hepatocytes. The persistent centrilobular lesions were not a consequence of impaired proliferative response in Plg(o) mice. Notably, fibrin deposition was a prominent feature in diseased centrilobular areas in Plg(o) livers for at least 30 days after injury. Nonetheless, the genetically superimposed loss of the Aalpha fibrinogen chain (Plg(o)/Fib(o) mice) did not correct the abnormal phenotype. These data show that plasminogen deficiency impedes the clearance of necrotic tissue from a diseased hepatic microenvironment and the subsequent reconstitution of normal liver architecture in a fashion that is unrelated to circulating fibrinogen.

Afibrinogenemia↗
PubMed1997

HLA class I and class II alleles and haplotypes in Mexican mestizos established from serological typing of 50 families.

We describe new information on the frequency and association of class II antigens (HLA-DR and HLA-DQ) of the major histocompatibility complex (MHC) in Mexicans. The study includes HLA-B typing and its association with the HLA-DR antigens determined in 50 families, which included 100 individuals. This family study allowed the establishment of the precise composition of the 200 HLA haplotypes, which cannot be obtained from unrelated individuals. The predominant antigens in decreasing order of frequency were B35, B39, and B61 at the B locus; DR4, DR5, and DR8 at the DR locus; and DQ3 at the DQ locus. The most common HLA-B,HLA-DR haplotype (considering broad specificities) was B16,DR4, with a frequency of 8.0%. Five HLA-B,HLA-DR haplotypes showed significant delta values (observed vs. expected frequencies) after correcting for the number of comparisons. On the other hand, the most common HLA-DR,HLA-DQ haplotypes were DR4,DQ3 and DR5,DQ3 with a frequency higher than 10%. Ten of the 17 HLA-DR,HLA-DQ haplotypes had significant postcorrection delta values.

Ethnicity↗
PubMed1994

HLA-B alleles and complotypes in Mexican patients with seronegative spondyloarthropathies.

OBJECTIVES: To analyse major histocompatibility complex (MHC) haplotypes in Mexican mestizo patients with seronegative spondyloarthropathies (SSpA) and normal controls, to discover if there are other antigens, besides B27, in the HLA region that might show association with the disease. METHODS: The study included 100 Mexican mestizo patients with SSpA and 200 of their first degree relatives. These groups were compared with 85 ethnically matched controls. The class I and class III MHC antigens were obtained by standard methods. The significance of differences between patients and controls was tested by chi 2 analysis; linkage disequilibrium among the different alleles in each haplotype was estimated by computing delta values. RESULTS: We found a significantly increased frequency of the HLA-B27 antigen (pcorr. = 1 x 10(-5), odds ratio (OR) = 33.4, 95% confidence interval (CI) = 9.3-142.0). In the group of 45 SSpA patients negative for the B27 antigen, independent increased frequencies of HLA-B49 antigen (pcorr. = 0.03, OR = 6.5, 95% CI = 1.5-32.8)) and the FC31 complotype (pcorr. = 0.04, OR = 3.7, 95% CI = 1.2-11.1) were found. Significant delta values were obtained for the [B27;SC30] haplotype (p = 0.0005) but not for haplotypes marked by the FC31 complotype. HLA-B antigens on the homologous chromosome in B27 positive patients were mainly HLA-B51 (18%) and HLA-B60 (16%); however, the observed genotypes B27/B51 and B27/B60 were not significantly different than expected from the allele frequencies alone. CONCLUSIONS: These data suggest that in Mexicans additional genes within the MHC region besides the HLA-B27 antigen, might be related to the genetic susceptibility for developing SSpA. Relevant antigens included the HLA-B49 and the FC31 complotype.

Adult↗
PubMed1992

Polymorphism in a T-cell receptor variable gene is associated with susceptibility to a juvenile rheumatoid arthritis subset.

This report demonstrates a T-cell receptor (Tcr) restriction fragment length polymorphism, defined by a Tcrb-V6.1 gene probe and Bgl II restriction enzyme, to be absolutely correlated with allelic variation in the coding sequence of a Tcrb-V6.1 gene. A pair of non-conservative amino acid substitutions distinguish the Tcrb-V6.1 allelic variants. An association of this Tcrb-V6.1 gene allelic variant with one form of juvenile rheumatoid arthritis (JRA) was established in a cohort of 126 patients. The association was observed in patients possessing the HLA-DQA1*0101 gene. Among HLA-DQA*0101 individuals, 19 of 26 patients (73.1%) carried one particular Tcrb-V6.1 gene allele as opposed to 11 of 33 controls (33%; p less than 0.005). Haplotypes carrying this HLA gene have previously been shown to confer increased risk for progression of arthritis in JRA. This demonstration of a disease-associated Tcrb-V gene allelic variant has not, to our knowledge, been previously reported and supports the contribution of polymorphism in the Tcr variable region genomic repertoire to human autoimmune disease.

Arthritis, Juvenile↗
PubMed1992

Human leukocyte antigen-DRB1*1104 in the chronic iridocyclitis of pauciarticular juvenile rheumatoid arthritis.

To determine whether genetic markers for chronic iridocyclitis could be identified, we used both serologic and oligonucleotide dot blot techniques to characterize immunogenetically 164 children with early-onset pauciarticular juvenile rheumatoid arthritis. Seventy-eight children (47.6%) had chronic iridocyclitis and 86 (52.4%) had not had evidence of eye disease during a mean follow-up period after the onset of arthritis of 15.8 years (minimum of 5.5 years). Control subjects were 218 healthy, unrelated individuals. The analysis was limited to alleles known to be associated with an increased or decreased risk of early-onset pauciarticular juvenile rheumatoid arthritis or of chronic iridocyclitis in this form of juvenile rheumatoid arthritis. Only one split of human leukocyte antigen (HLA)-DR5, HLA-DRB1* 1104, showed a statistically significant association with a risk of chronic iridocyclitis (chi-square value = 7.52; p = 0.036 adjusted; odds ratio 3.45); HLA-DQA1* 0501 and HLA-DQB1* 0301, both in linkage disequilibrium with HLA-DRB1* 1104, also were significantly associated with eye disease. Patients with both the DRB1* 1104 and DPB1* 0201 genes had a 7.7-fold increased risk for chronic iridocyclitis compared with that for other patients. The presence of HLA-DRB1* 1104 was about four times as specific, but only about one third as sensitive, as antinuclear antibodies in identifying patients at risk for eye disease. Although all children with early-onset pauciarticular juvenile rheumatoid arthritis should undergo periodic slit-lamp examinations, those with the HLA class II gene DRB1* 1104 are at particularly high risk for eye disease, and we recommend that they be monitored carefully for its evolution.

Adult↗
PubMed1991

HLA-DQA1*0101 haplotypes and disease outcome in early onset pauciarticular juvenile rheumatoid arthritis.

To further investigate a clinical impression that patients with early onset pauciarticular juvenile rheumatoid arthritis (EOPA-JRA) who carry HLA-DQw1 have more severe arthritis, we subtyped HLA-DQw1 in American midwestern patients with EOPA-JRA. The HLA-DQA1*0101 subtype was present in 10 of 19 patients who developed persistent polyarticular erosive disease compared with 18 of 92 healthy controls (chi 2 = 9.13, p = 0.003, RR = 4.6), and occurred more frequently in this polyarticular group than in patients without polyarticular erosive disease (chi 2 = 4.11, p = 0.040, RR = 3.0). The presence of HLA-DQA1*0101 was significantly lower in patients with chronic iridocyclitis than in patients without chronic iridocyclitis (chi 2 = 7.07, p = 0.008, RR = 0.21). In HLA-DQA1*0101 positive patients, DNA sequences of the beta-1 domain of the HLA-DQ alpha and HLA-DQ beta genes (HLA-DQA1*0101, HLA-DQB1*0501 and HLA-DQB1*0503) were identical to those in controls. In this midwestern EOPA-JRA population, HLA-DQA1*0101 or genes in linkage disequilibrium with it, are associated with a cohort of patients with EOPA-JRA with distinct clinical characteristics.

Alleles↗
PubMed1990

A distinct HLA-DRw8 haplotype characterizes patients with juvenile rheumatoid arthritis.

We studied the first domain of the HLA-DRB1, HLA-DQA1, and HLA-DQB1 loci of 67 HLA-DRw8-positive Caucasians including 43 with early-onset pauciarticular juvenile rheumatoid arthritis (EOPA-JRA, alternatively known as early-onset pauciarticular juvenile chronic arthritis). Serology, restriction fragment length polymorphism (RFLP), and polymerase chain reaction (PCR) oligotyping revealed that 62, including all the EOPA-JRA patients, carried the HLA-DRB1*0801, DQA1*0401, DQB1*0402 genotype. Approximately one-fifth of the controls carried atypical HLA-DRB1, HLA-DQA1, and/or HLA-DQB1 loci on their HLA-DRw8 haplotype confirmed by family studies. DNA sequences of HLA-DRB1, DQA1, and DQB1 alleles in patients and controls were identical to those previously reported. Disease association studies in 113 EOPA-JRA patients and 207 controls unselected for HLA-DRw8 revealed that the HLA-DRB1*0801, DQA1*0401, DQB1*0402 genotype was associated with a higher relative risk (RR) for disease (RR = 12.8, chi 2 = 48.8, P less than 10(-4)) than was the serologically defined presence of HLA-DRw8 (RR = 8, chi 2 = 39, P less than 10(-4)). Further analysis suggested that the DQ genes on HLA-DRw8 haplotypes are as likely as the DR genes to contribute to the pathogenesis of EOPA-JRA. This study increases to five the number of HLA-DR/DQ haplotypes identified in HLA-DRw8 Caucasians.

Arthritis, Juvenile↗
PubMed1990

Immunogenetics of early onset pauciarticular juvenile rheumatoid arthritis.

Certain major histocompatibility complex (MHC) class I and class II genes are uniquely associated with early onset pauciarticular juvenile rheumatoid arthritis (JRA). As in other autoimmune diseases, these associations are likely to reflect contributions of the MHC to a trimolecular complex formed by HLA, lymphocyte T cell receptor and the putative antigen. The HLA genes associated with JRA are currently the best understood component of this complex. Recent findings demonstrated that combinations of genes, even within class II, play an important role. Data generated by DNA sequencing techniques have clarified the splits of given genes involved in disease, e.g., the HLA-DRw8 allele, HLA-DRB1*0801 rather than HLA-DRB1*0802, which does not carry an increased risk for disease. Recent findings suggest that aberrant sequences in particular genes are unimportant. Substantial challenges remain; including establishing the particular HLA DNA nucleotides critical to antigen presentation. It is probable that new and specific therapeutic approaches will be developed which will utilize the immunogenetic data now being accumulated.

Adolescent↗