Structural polymorphism of glycophorins demonstrated by immunoblotting techniques

We have explored the polymorphism of the glycophorin system in the human erythrocyte membrane using the immunoblotting techniques and examining 52 individuals selected without prior bias as to their serologic state and ten documented serologic variants of M, N, S, s blood group system. Polyclonal antisera to alpha glycophorin and to alpha glycophorin CNBr carboxyl terminal fragment C (residues 82-131) and M and N specific monoclonal antibodies (MoAbs) were used. The first two reagents detect specific regions of the alpha glycophorin molecule and all electrophoretically resolved species of glycophorins immunologically related to alpha and delta glycophorins (delta glycophorin, [alpha-delta] hybrids and other glycophorins with an alteration in the carboxyl terminal segment); the M and N MoAbs identified the glycophorin species containing or lacking the M or N determinant in the amino terminal octapeptide structures. We find that immunoblotting confirmed in all cases the serologically determined phenotype; we also find that polymorphic forms of the glycophorin system are relatively infrequent; immunoblotting, independent from serologic testing, was capable of detecting five mutants, two most likely S-s-U-phenotypes; a new glycophorin species was detected in normal red cells with both antiglycophorin and antipeptide C sera, which is not evident with MoAbs; immunoblots of known glycophorin variants (En(a-), U-, Mg, Mi I, II, III, V, and Sta) confirmed but also extended our knowledge of the abnormal glycophorins involved; and the He+ and Wrb(-) cells showed normal patterns.     

Melatonin and aging: in vitro effect of young and mature ring dove physiological concentrations of melatonin on the phagocytic function of heterophils from old ring dove.

We have studied the circadian rhythm of melatonin in the ring dove (Streptopelia risoria) for different age groups: young (1-1.5 years), mature (3-4 years) and old animals (>8 years). Melatonin levels were determined by radioimmunoassay. Results showed a significant decline in plasma melatonin levels in old animals when compared with the concentrations observed in the other two age groups, in which maximum (nocturnal) concentrations were 300 pg/ml and minimum (diurnal) concentrations were 50 pg/ml. We analyzed the in vitro effect of the physiological concentrations found in young and mature animals on the heterophils obtained from old animals, evaluating the capacity for ingestion and destruction of Candida albicans, and the oxidative metabolism associate to phagocytosis by determining the superoxide anion levels. Melatonin induced an increase in both the phagocytosis index and the candidicide capacity. This effect was dose-dependent. In relation with the oxidative metabolism, a decline in superoxide anion levels after incubation with both concentrations of the hormone was observed. Thus our results corroborate in this avian species the decline in plasma melatonin levels with advanced age, as well as the enhancing effect of physiological concentrations of melatonin on the phagocytic function.     

Biliary strictures after liver transplantation. Predictive factors for response to endoscopic management and long-term outcome

BACKGROUND: Biliary strictures after liver transplantation are frequent. The long-term prognosis and predictive factors of response to endoscopic treatment are not well known. METHODS: The aim of this study was to demonstrate the role of endoscopic treatment, predictive factors of response, and outcome in patients with biliary stricture after liver transplantation. We performed a retrospective review of medical records of all consecutive post-liver transplantation patients who underwent endoscopic retrograde cholangiography in our center during the period from October 2001 to October 2006. RESULTS: Twenty-five of 43 patients referred for endoscopic retrograde cholangiography had biliary stricture. Eighteen had stricture at the area of the anastomosis alone, 2 patients had a stricture at the area of the anastomosis and also another area, and 5 had nonanastomotic biliary strictures. Twenty-one patients had a single stricture and 4 had more than 1 stricture. Initially 19 of 24 patients (79%) responded to endoscopic management with normalization of liver enzymes. Four patients (16%) did not respond clinically despite a successful endoscopic approach. All patients who did not respond to endoscopic dilation had more than 1 area of stricture. There was a significantly better response to endoscopic treatment in patients with an anastomotic stricture versus patients with nonanastomotic strictures 17/19 versus 2/5 (P = 0.042). CONCLUSIONS: In our experience, endoscopic treatment of anastomotic biliary strictures is highly effective with a good long-term outcome. The presence of nonanastomotic and multiple strictures should be considered a factor associated with poor response to endoscopic management.     

Phenotypic characterization and predictive analysis of p.Asp47Asn LDL receptor mutation associated with Familial Hypercholesterolemia in a Chilean population

BackgroundFamilial hypercholesterolemia (FH) is an inherited disorder mainly caused by mutations in the LDL receptor (LDL-R) and characterized by elevation of low-density lipoprotein cholesterol (LDL-C) levels and premature cardiovascular disease.ObjectiveIn this study, we evaluated the clinical phenotype of the p.Asp47Asn, described as an uncertain pathogenic variant, and its effect on the structure of LDL-R and ligand interactions with apolipoproteins.Methods27 children and adolescents with suspected FH diagnosis were recruited from a pediatric endocrinology outpatient clinic. Blood samples were collected after 12 h fasting for lipid profile analysis. DNA sequencing was performed for six FH-related genes by Ion Torrent PGM platform and copy number variation by MLPA. For index cases, a familial cascade screening was done restricted to the same mutation found in the index case. In silico analysis were developed to evaluate the binding capacity of LDL-R to apolipoproteins B100 and E.ResultsLipid profile in children and adolescents demonstrated higher LDL-C levels in p.Asp47Asn carriers compared to the wild type genotype. In silico analysis predicted a reduction in the binding capacity of the ligand-binding modules LA1-2 of p.Asp47Asn LDL-R for ApoB100 and ApoE, which was not produced by local structural changes or folding defects but as a consequence of a decreased apparent affinity for both apolipoproteins.ConclusionThe clinical phenotype and the structural effects of p.Asp47Asn LDL-R mutation suggest that this variant associates to FH.     

Monte Carlo method for the evaluation of symptom association

Gastroesophageal monitoring is limited to 96 hours by the current technology. This work presents a computational model to investigate symptom association in gastroesophageal reflux disease with larger data samples proving important deficiencies of the current methodology that must be taking into account in clinical evaluation. A computational model based on Monte Carlo analysis was implemented to simulate patients with known statistical characteristics Thus, sets of 2000 10‐day‐long recordings were simulated and analyzed using the symptom index (SI), the symptom sensitivity index (SSI), and the symptom association probability (SAP). Afterwards, linear regression was applied to define the dependency of these indexes with the number of reflux, the number of symptoms, the duration of the monitoring, and the probability of association. All the indexes were biased estimators of symptom association and therefore they do not consider the effect of chance: when symptom and reflux were completely uncorrelated, the values of the indexes under study were greater than zero. On the other hand, longer recording reduced variability in the estimation of the SI and the SSI while increasing the value of the SAP. Furthermore, if the number of symptoms remains below one‐tenth of the number of reflux episodes, it is not possible to achieve a positive value of the SSI. A limitation of this computational model is that it does not consider feeding and sleeping periods, differences between reflux episodes or causation. However, the conclusions are not affected by these limitations. These facts represent important limitations in symptom association analysis, and therefore, invasive treatments must not be considered based on the value of these indexes only until a new methodology provides a more reliable assessment.     

Nummular headache secondary to an intracranial mass lesion

Nummular headache is a coin-shaped, chronic cephalalgia usually considered to stem from epicranial tissues. We describe a patient complaining of circumscribed pain in the head as the only symptom of a subtentorial meningioma. This observation underlines the need to revise the concept of circumscribed, referred pains in the head arising from pain-sensitive intracranial structures.     

Molecular epidemiology of Burkitt's lymphoma from South America: differences in breakpoint location and Epstein-Barr virus association from tumors in other world regions.

We have previously shown that the endemic (African) and sporadic (North American) forms of Burkitt's lymphoma (BL) differ at a molecular level. We have now extended our studies to the molecular epidemiology of BL in South America, specifically to two climatic regions: temperate (Argentina and Chile) and tropical (Brazil). We have examined the patterns of chromosomal breakpoint locations in 39 tumors with respect to geography and Epstein-Barr virus (EBV) association. The result of these analyses provide further support for the existence of pathogenetically distinct subtypes of BL in different world regions. The majority of breakpoints on chromosome 8 in South American BL (41%) occurred in the immediate flanking region of c-myc, ie, further 5' of the "typical" sporadic breakpoints, in the first exon/intron region, and further 3' of the "typical" endemic breakpoints, which are usually distant from c-myc. However, the distribution of breakpoints on chromosome 14 in tumors from the temperate and tropical regions of South America is similar to that observed in sporadic and endemic tumors. Interestingly, only one tumor with an unrearranged c-myc gene joined to the S mu region of chromosome 14 was observed. This combination was also rarely observed in our earlier series and presumably is either less readily generated by the mechanism that mediates 8;14 translocation or requires other, infrequent genetic changes to provide the necessary selective advantage for lymphomagenesis. The frequency of EBV association in South American BL (51%) is also intermediate with respect to tumors from the United States (30%) and Africa (100%). No correlation with the breakpoint location on chromosome 8 was discernable. Surprisingly, only 54% of tumors with breakpoint outside c-myc were EBV positive. This is in contrast to endemic tumors and suggests that any pathogenetic contribution of EBV is not dependent on breakpoint location, but is more likely to complement additional pathogenetic elements that differ in different world regions.     

Stem cell transplantation in patients with severe congenital neutropenia without evidence of leukemic transformation

Severe congenital neutropenia (CN) (Kostmann syndrome) is a hematologic disorder characterized by a maturation arrest of myelopoiesis at the promyelocyte/myelocyte stage of development. This arrest results in severe neutropenia leading to absolute neutrophil counts (ANC) below 0.2 x 10(9)/L associated with severe bacterial infections from early infancy. Data on over 300 patients with CN collected by the Severe Chronic Neutropenia International Registry (SCNIR) beginning in 1994 indicate that more than 90% of these patients respond to recombinant human granulocyte-colony stimulating factor (r-HuG-CSF) treatment with an ANC greater than 1. 0 x 10(9)/L. For patients who are refractory to r-HuG-CSF treatment and continue to have severe and often life-threatening bacterial infections, hematopoietic stem cell transplantation is the only currently available treatment. We report on a total of 11 patients with CN reported to the SCNIR who underwent transplantation for reasons other than malignant transformation between 1976 and 1998. Of these patients, 8 were nonresponders or showed only partial response to r-HuG-CSF treatment with ongoing infections. Results from these patients suggest that transplantation of stem cells from an HLA-identical sibling is beneficial for patients refractory to r-HuG-CSF. (Blood. 2000;95:1195-1198)     

Risk of Type 1 Diabetes Progression in Islet Autoantibody-Positive Children Can Be Further Stratified Using Expression Patterns of Multiple Genes Implicated in Peripheral Blood Lymphocyte Activation and Function

There is tremendous scientific and clinical value to further improving the predictive power of autoantibodies because autoantibody-positive (AbP) children have heterogeneous rates of progression to clinical diabetes. This study explored the potential of gene expression profiles as biomarkers for risk stratification among 104 AbP subjects from the Diabetes Autoimmunity Study in the Young (DAISY) using a discovery data set based on microarray and a validation data set based on real-time RT-PCR. The microarray data identified 454 candidate genes with expression levels associated with various type 1 diabetes (T1D) progression rates. RT-PCR analyses of the top-27 candidate genes confirmed 5 genes (BACH2, IGLL3, EIF3A, CDC20, and TXNDC5) associated with differential progression and implicated in lymphocyte activation and function. Multivariate analyses of these five genes in the discovery and validation data sets identified and confirmed four multigene models (BI, ICE, BICE, and BITE, with each letter representing a gene) that consistently stratify high- and low-risk subsets of AbP subjects with hazard ratios >6 (P < 0.01). The results suggest that these genes may be involved in T1D pathogenesis and potentially serve as excellent gene expression biomarkers to predict the risk of progression to clinical diabetes for AbP subjects.