Interaction of beta-lactoglobulin with retinol and fatty acids and its role as a possible biological function for this protein: a review

beta-Lactoglobulin is the major whey protein in the milk of ruminants and some nonruminants, such as pigs and horses. Although beta-lactoglobulin was first isolated 60 yr ago, no function has been definitely ascribed to beta-lactoglobulin. Recent x-ray crystallographic studies have advanced knowledge of the structure of beta-lactoglobulin, which is homologous with that of retinol-binding protein and lipocalycins; the function of these proteins seems to be participation in the transport of small hydrophobic substances. By analogy, this protein has been suggested as having a role as a transporter of fatty acids and retinol. This review reassesses the function of beta-lactoglobulin in light of the large amount of information that has accrued in the last few years. In particular, this review concentrates upon studies of the binding of retinol and fatty acids to beta-lactoglobulin, including the binding constants and number of binding sites, the location of the binding sites, and the influence of chemical modifications in the interaction of the protein with both ligands. This study also describes studies of the influence of beta-lactoglobulin on several biological processes that may be relevant to the possible biological role of this protein.

Safety of thiopurines and anti-TNF-α drugs during pregnancy in patients with inflammatory bowel disease

OBJECTIVES

The safety of thiopurines and anti-tumor necrosis factor-α (TNF-α) drugs during pregnancy remains controversial, as the experience with these drugs in this situation is limited. Our aim is to assess the safety of thiopurines and anti-TNF-α drugs for the treatment of inflammatory bowel disease (IBD) during pregnancy.

METHODS

Retrospective, multicenter study in IBD patients. Pregnancies were classified according to the therapeutic regimens during pregnancy or during the 3 months before the conception: non-exposed group, pregnancies exposed to thiopurines alone (group A), and pregnancies exposed to anti-TNF-α drugs (group B). An unfavorable Global Pregnancy Outcome (GPO) was considered if pregnancy developed with obstetric complications in the mother and in the newborn.

RESULTS

A total of 187 pregnancies in the group A, 66 pregnancies in the group B, and 318 pregnancies in the non-exposed group were included. The rate of unfavorable GPO was different among the three groups (31.8% in non-exposed group, 21.9% in group A, and 34.8% in group B), being lower in pregnancies under thiopurines than among non-exposed (P = 0.01). The rate of pregnancy complications was similar among the three groups (27.7% in non-exposed, 20.9% in group A, and 30.3% in group B). The rate of neonatal complications was different among the three groups (23.3% in non-exposed group, 13.9% in group A, and 21.2% in group B), being lower in pregnancies under thiopurines than among non-exposed (P = 0.01). In the multivariate analysis, the treatment with thiopurines (odds ratio = 0.6; 95% confidence interval = 0.4-0.9, P = 0.02) was the only predictor of favorable GPO, whereas maternal age >35 years at conception was the only predictor of unfavorable GPO. The treatment with anti-TNF-α drugs was not associated with an unfavorable GPO.

CONCLUSION

The treatment with thiopurines and anti-TNF-α drugs does not seem to increase the risk of complications during pregnancy and does seem to be safe for the newborn.

Interaction of fatty acids with beta-lactoglobulin and albumin from ruminant milk

beta-Lactoglobulin isolated from milk of cow, sheep, and goat had about 0.5 mol of fatty acids bound per mol of monomer protein. Fatty acids, mainly palmitic and oleic acids, were the major components (about 75% of total lipids). Albumin isolated from the same samples had about 4.5 mol of fatty acids bound per mol of protein. These two proteins were the only whey proteins able to bind labeled fatty acids in vitro. Interaction of beta-lactoglobulin and albumin with insolubilized fatty acids showed some differences, suggesting different structures of the respective fatty acid binding sites.

Acute pancreatitis in inflammatory bowel disease, with special reference to azathioprine-induced pancreatitis

BACKGROUND

Pancreatitis is a potentially severe condition. Patients with inflammatory bowel disease (IBD) seem to be at increased risk for acute pancreatitis.

AIM

To describe the incidence, main causes and possible predictive factors of acute pancreatitis in inflammatory bowel disease.

METHODS

Information was retrospectively extracted from the clinical records of patients followed in the IBD Units of nine hospitals in Madrid (n = 5073).

RESULTS

A total of 82 acute pancreatitis episodes were diagnosed (cumulative incidence, 1.6%); 98% of them were mild. Recurrent acute pancreatitis developed in 13% of patients. Most cases of acute pancreatitis (63.4%) were attributed to drug exposure [azathioprine/mercaptopurine (AZA/MP) n = 46, mesalazine (mesalamine) n = 6]; 20.7% were idiopathic, and 12.2% were biliary. Incidence of acute pancreatitis in patients treated with AZA/MP was 3.1%. In patients with acute pancreatitis, female gender (OR 3.4 95% CI: 1.3-9.3; P = 0.012) and Crohn's disease (CD) (OR 5.8 95% CI: 1.6-20.6; P = 0.007) were risk factors for AZA/MP-associated acute pancreatitis, the latter also when analysed only in patients treated with AZA/MP (n = 1477) (OR 5.2 95% CI: 1.8-14; P = 0.002).

CONCLUSIONS

The incidence of acute pancreatitis in our IBD patients (1.6%) is similar to that previously described. Drugs, mainly AZA/MP, are the leading cause. AZA-induced acute pancreatitis is always mild. Patients with CD are at a higher risk for AZA/MP-associated acute pancreatitis. The frequency of idiopathic acute pancreatitis is higher than expected, suggesting that part of these cases could be extraintestinal manifestations of IBD.

Clinical patterns and outcomes of ischaemic colitis: results of the Working Group for the Study of Ischaemic Colitis in Spain (CIE study)

BACKGROUND

There is a lack of prospective studies evaluating the natural history of colonic ischaemia (CI). We performed such a study to evaluate the clinical presentation, outcome, and mortality as well as clinical variables associated with poor prognosis.

METHODS

An open, prospective, and multicentre study was conducted in 24 Spanish hospitals serving a population of 3.5 million people. The study included only patients who met criteria for definitive or probable CI. A website (www.colitisisquemica.org) provided logistical support.

RESULTS

A total of 364 patients met criteria for inclusion. CI was suspected clinically in only 24.2% of cases. The distribution of clinical patterns was as follows: reversible colopathy (26.1%), transient colitis (43.7%), gangrenous colitis (9.9%), fulminant pancolitis (2.5%), and chronic segmental colitis (17.9%). A total of 47 patients (12.9%) had an unfavorable outcome as defined by mortality and/or the need for surgery. Multivariate analysis identified the following signs as independent risk factors for an unfavorable outcome: abdominal pain without rectal bleeding [odds ratio (OR) 3.9; 95% confidence interval (CI) = 1.6-9.3], non-bloody diarrhoea (OR 10; 95% CI = 3.7-27.4), and peritoneal signs (OR 7.3; 95% CI = 2.7-19.6). Unfavorable outcomes also were more frequent in isolated right colon ischaemia (IRCI) compared with non-IRCI (40.9 vs. 10.3%, respectively; p < 0.0001). The overall mortality rate was 7.7%.

CONCLUSIONS

The clinical presentation of CI is very heterogeneous, perhaps explaining why clinical suspicion of this disease is so low. The presence of IRCI, and occurrence of peritoneal signs or onset of CI as severe abdominal pain without bleeding, should alert the physician to a potentially unfavorable course.

Concentration of lactoferrin and transferrin throughout lactation in cow's colostrum and milk

The evolution of the concentration of lactoferrin and transferrin was studied in cow's colostrum and milk throughout lactation. The highest concentrations of both proteins were found in the first milking (0.83 mg/ml for lactoferrin and 1.07 mg/ml for transferrin), decreasing sharply during the first days of lactation (colostral period). Thereafter, the concentrations of these proteins decreased slowly, reaching their definitive values during the third week post-partum (0.09 mg/ml for lactoferrin and 0.02 mg/ml for transferrin). The ratio transferrin/albumin in colostrum (first milking), mature milk, milk from mastitic cows and serum was determined, and found to be four times greater in colostrum than in mature or mastitic milk, suggesting a specific transport of transferrin from blood to milk.

Isolated endosomes from quiescent rat liver contain the signal transduction machinery. Differential distribution of activated Raf-1 and Mek in the endocytic compartment

In this study we identify the molecules involved in the MAPK signal transduction pathway (Ras, Raf-1, Mek, Mek-P and MAPK) in highly purified endosomal fractions isolated from rat liver. Biochemical analysis shows that only the early-sorting endocytic compartment contains activated Raf-1 and Mek. Finally, the exogenous administration of EGF led to redistribution of Raf-1 from the caveolin-enriched plasma membrane into the endosomes.

Studies in owl monkeys leading to the development of a synthetic vaccine against the asexual blood stages of Plasmodium falciparum

During the development of a synthetic vaccine for human use against the asexual blood stages of Plasmodium falciparum, monkey trials were performed to assess safety, immunogenicity, and protectivity. We determined the minimal infective dose of the P. falciparum FVO strain, the kinetics of the immune response induced by vaccination with the synthetic peptide mixture (S7 + S12 + S17) or the synthetic hybrid polymeric protein SPf66, and the induction of protective immunity against the experimental challenge with 2 P. falciparum strains. A clear boosting effect was observed, determined by the increased antibody titers against synthetic peptides S7, S12, S17, and SPf66, and by improvement in the protective immune response against the challenge. These studies suggest that either the peptide mixture or the synthetic hybrid polymeric protein are excellent choices for the development of a vaccine against P. falciparum.

Evaluation of two rapid ultrafiltration-based methods for SARS-CoV-2 concentration from wastewater

Quantitative measurements of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in raw wastewater have been implemented worldwide since the beginning of the pandemic. Recent efforts are being made to evaluate different viral concentration methodologies to overcome supplier shortages during lockdowns. A set of 22-wastewater samples seeded with murine hepatitis virus (MHV), a member of the Coronaviridae family, and the bacteriophage MS2, were used to characterize and compare two ultrafiltration-based methods: a centrifugal ultrafiltration device (Centricon® Plus-70) and the automated concentrating pipette CP-Select™. Based on the recovery efficiencies, significant differences were observed for MHV, with Centricon® Plus-70 (24%) being the most efficient method. Nevertheless, concentrations of naturally occurring SARS-CoV-2, Human adenoviruses and JC polyomaviruses in these samples did not result in significant differences between methods suggesting that testing naturally occurring viruses may complement the evaluation of viral concentration methodologies. Based on the virus adsorption to solids and the necessity of a pre-centrifugation step to remove larger particles and avoid clogging when using ultrafiltration methods, we assessed the percentage of viruses not quantified after ultrafiltration. Around 23% of the detected SARS-CoV-2 would be discarded during the debris removal step. The CP-Select™ provided the highest concentration factor (up to 333×) and the lowest LoD (6.19 × 103 GC/l) for MHV and proved to be fast, automatic, highly reproducible and suitable to work under BSL-2 measures.

Dyrk1A influences neuronal morphogenesis through regulation of cytoskeletal dynamics in mammalian cortical neurons

Down syndrome (DS) is the most frequent genetic cause of mental retardation. Cognitive dysfunction in these patients is correlated with reduced dendritic branching and complexity, along with fewer spines of abnormal shape that characterize the cortical neuronal profile of DS. DS phenotypes are caused by the disruptive effect of specific trisomic genes. Here, we report that overexpression of dual-specificity tyrosine phosphorylation-regulated kinase 1A, DYRK1A, is sufficient to produce the dendritic alterations observed in DS patients. Engineered changes in Dyrk1A gene dosage in vivo strongly alter the postnatal dendritic arborization processes with a similar progression than in humans. In cultured mammalian cortical neurons, we determined a reduction of neurite outgrowth and synaptogenesis. The mechanism underlying neurite dysgenesia involves changes in the dynamic reorganization of the cytoskeleton.

Interaction of bovine lactoferrin with other proteins of milk whey

The association between bovine lactoferrin and the major bovine whey proteins, beta-lactoglobulin, alpha-lactalbumin and albumin has been studied by immunochemical techniques, gel filtration and affinity chromatography in lacteal secretions and using purified proteins. Bovine lactoferrin is able to form non-covalent complexes with beta-lactoglobulin or albumin, with lactoferrin-protein molar ratios of 2:1 and 1:1 respectively. No association was detected with alpha-lactalbumin. Lactoferrin interacts with beta-lactoglobulin-Sepharose at low ionic strength, but not in the presence of 0.3 M NaCl, indicating that ionic interactions are important. The lack of association with alpha-lactalbumin suggests however a certain degree of specificity in this electrostatic interaction.

Phenotype and natural history of elderly onset inflammatory bowel disease: a multicentre, case-control study

BACKGROUND

Onset during old age has been reported in upto 10% of total cases of inflammatory bowel disease (IBD).

AIM

To evaluate phenotypic characteristics and the use of therapeutic resources in patients with elderly onset IBD.

METHODS

Case-control study including all those patients diagnosed with IBD over the age of 60 years since 2000 who were followed-up for >12 months, identified from the IBD databases. Elderly onset cases were compared with IBD patients aged 18 to 40 years at diagnosis, matched by year of diagnosis, gender and type of IBD (adult-onset).

RESULTS

One thousand three hundred and seventy-four elderly onset and 1374 adult-onset cases were included (62% ulcerative colitis (UC), 38% Crohn's disease (CD)). Among UC patients, elderly onset cases had a lower proportion of extensive disease (33% vs 39%; P < 0.0001). In CD, elderly onset cases showed an increased rate of stenosing pattern (24% vs 13%; P < 0.0001) and exclusive colonic location (28% vs 16%; P < 0.0001), whereas penetrating pattern (12% vs 19%; P < 0.0001) was significantly less frequent. Regarding the use of therapeutic resources, there was a significantly lower use of corticosteroids (P < 0.0001), immunosuppressants (P < 0.0001) and anti-TNFs agents (P < 0.0001) in elderly onset cases. Regarding surgery, we found a significantly higher surgery rate among elderly onset UC cases (8.3% vs 5.1%; P < 0.009). Finally, elderly onset cases were characterised by a higher rate of hospitalisations (66% vs 49%; P < 0.0001) and neoplasms (14% vs 0.5%; P < 0.0001).

CONCLUSIONS

Elderly onset IBD shows specific characteristics and they are managed differently, with a lower use of immunosuppressants and a higher rate of surgery in UC.

Effect of beta-lactoglobulin on the activity of pregastric lipase. A possible role for this protein in ruminant milk

The interaction of bovine beta-lactoglobulin with palmitic and oleic acids has been studied by a partition equilibrium method. Bovine beta-lactoglobulin displays only one high affinity binding site for fatty acids whose association constants for palmitic and oleic acids are 4.2 x 10(6) and 2.3 x 10(6) M-1, respectively. However, other binding sites with low affinity are also present. The existence of one high affinity binding site is in accordance with the amount of fatty acids naturally bound to beta-lactoglobulin isolated from milk. The effect of beta-lactoglobulin on ruminant pregastric lipases from a pharyngeal extract has been assayed. The activity of pharyngeal lipase on a triglyceride emulsion is increased about 200%, 250% and 190% in the presence of 10 mg/ml, 20 mg/ml and 40 mg/ml of beta-lactoglobulin, respectively, the last concentration representing that found physiologically in colostrum. Albumin, another ligand-binding protein, increases the activity of this enzyme to a lesser extent and high levels tend to inhibit enzyme action. These results indicate that beta-lactoglobulin could participate in the digestion of milk lipids during the neonatal period by enhancing the activity of pregastric lipase through removal of the fatty acids that inhibit this enzyme.

Comparison and applicability of molecular classifications for gastric cancer

Gastric Cancer (GC) is a complex and heterogeneous disease, which represents a global health concern. Despite advances in prevention, diagnosis, and therapy, GC is still a leading cause of cancer-related death. Over the last decade, several clinical trials have tested novel agents for advanced GC with mostly disappointing results. Heterogeneity, the absence of molecular selection in clinical trials and powerless predictive biomarkers may be potential explanations. Different molecular classification proposals for GC based on the genetic, epigenetic, and molecular signatures have been published. Molecular characterization of GC may offer new tools for more effective therapeutic strategies, such as the development of therapies for specifically well-defined sets of patients as well as the use of new clinical trial designs, which will ultimately lead to an improvement of medical management of this disease. However, the possibilities of implementation of GC molecular classifications on daily practice and their therapeutic implications remain challenging to date. In this review, we will describe and compare these GC molecular classifications, focusing on their main characteristics as the basis for their potential therapeutic implications and strategies for their clinical application. Key Message: A better understanding of gastric cancer molecular characteristics may lead to further improvements in treatment and outcomes for patients with the disease.

Effect of heat treatment on the antigen-binding activity of anti-peroxidase immunoglobulins in bovine colostrum

After intramammary immunization with horseradish peroxidase, bovine colostrum containing anti-peroxidase immunoglobulins (Ig) was obtained. Thermoresistance of the antigen-binding region of these Ig was studied using a direct competitive ELISA. This technique is based on the competition between the anti-peroxidase IgG coated to the plate and the anti-peroxidase IgG contained in the colostrum to bind peroxidase, the antigen, and the enzyme responsible for development of the color of the assay. Thus, the degree of denaturation of the antigen-binding region in the IgG molecule can be determined because this region is directly involved in the assay. The kinetic and thermodynamic parameters for heat induced denaturation of IgG in colostrum were determined over a temperature range of 69 to 81 degrees C. The denaturation of IgG was best described assuming an apparent reaction order of 1.5. D values, the time required to reduce the antigen-binding activity of IgG by 90%, were 8504, 1387, 285, and 152 s at 69, 72, 77, and 81 degrees C, respectively. Similarly, Z value, the degrees necessary to reduce the D value in one logarithmic cycle, was estimated to be 6.6 degrees C, and the activation energy value was 386.83 kJ/mol. These results should be taken into account in the design of heat treatments of milk in order to preserve the biological function of Ig.

Antiribosomal P protein antibodies in Chilean SLE patients: no association with renal disease

The objective of this work was to determine the frequency and clinical associations of anti-ribosomal P protein antibodies (Anti-P) in a cohort of Chilean patients with systemic lupus erythematosus (SLE). Between 1996 and 1998, 141 consecutive patients with SLE were examined prospectively according with a standard protocol. Disease activity was measured by MEX-SLEDAI in 138 patients. Anti-P positivity was determined by double immune diffusion or Western blot and ELISA. Anti-P was found in 21 (15%) patients. In the Anti-P positive patients recent onset SLE (disease duration of 1 year or less) was more frequent (P = 0.018). Anti-P was found in 23% of 83 patients with active SLE vs 4% of the 55 patients with inactive SLE (Yates corrected P = 0.00479). An association with anti-dsDNA antibodies by Farr assay was observed. Anti-P positive patients had a median Farr of 65 IU/ml (1.4-1240) and Anti-P negative of 12 IU/ml (1.4-992; P-value = 0.0084). During the study only two patients had lupus psychosis and they were Anti-P positive. No association was found with liver disease (six patients, two with Anti-P antibodies) or active glomerulonephritis (22 patients four with Anti-P). Our data shows that the presence of Anti-P antibodies supports the clinical diagnosis of lupus psychosis.

The "early-sorting" endocytic compartment of rat hepatocytes is involved in the intracellular pathway of caveolin-1 (VIP-21)

The sinusoidal plasma membrane of the hepatocyte is organized into functional and structural microdomains whose origin, maintenance, and functioning are closely related with the endocytic compartment. Three different subcellular fractions, from rat liver, containing caveolin-1, the structural protein of caveolae, were morphologically and biochemically characterized. A caveolae-enriched plasma membrane fraction (CEF), contains large membrane structures surrounding attached internal plasmalemmal vesicles; the receptor-recycling compartment (RRC), contains tubules and vesicles with similar morphology to the internal vesicles observed by electron microscopy in CEF; and finally, caveolin-1 was also detected in early-sorting endosomes (CURL, compartment of uncoupling receptors and ligands). In this study, we show that following an intravenous administration of retinol-binding protein (RBP), there was a redistribution of caveolin-1 from the plasma membrane (CEF) to intracellular endocytic compartments (RRC and early-sorting endosomes). Thus, these results indicate that, in the hepatocyte, caveolae are dynamic structures actively interacting with the endocytic compartment.

Comparative analysis of viral pathogens and potential indicators in shellfish

Shellfish can be responsible of outbreaks of infectious diseases and current health measures do not guarantee the absence of viral pathogens in this product. Here we examine the presence of pathogenic viruses and potential indicators in shellfish in a comparative analysis.Sixty shellfish samples collected in three areas with different levels of faecal contamination were analysed for Escherichia coli, total coliforms, Clostridium perfringens, somatic coliphages, F-specific phages of RNA (F-RNA), bacteriophages infecting Bacteroides fragilis RYC2056, human adenovirus, enterovirus and hepatitis A virus (HAV). Viruses were eluted in a glycine buffer at pH 10. The overall percentage of viral pathogens detected was 47% for human adenoviruses, 19% for enteroviruses and 24% for HAV. Since all the samples positive for enterovirus and HAV were also positives for human adenovirus, the latter may be considered useful as a molecular index of viral contamination in shellfish. No significant differences in the bioaccumulation of bacteria and bacteriophages for oysters or mussels were observed. It was found that the probability of detection of any of the pathogenic virus decreases as the temperature of shellfish growing waters increases. However, the probability of detecting viruses increases when phages of B. fragilis are found. Although more data are needed in order to fulfil the need of viral indicators for controlling the presence of human viruses in shellfish, the obtained results indicate that phages infecting B. fragilis RYC2056 could be a suitable group of bacteriophages to be used as an indicator of the presence of viruses in shellfish.

Morphologic and functional characterization of caveolae in rat liver hepatocytes

Caveolae are small pits on the plasma membrane found in several, if not all, differentiated cells. They are involved in potocytosis, endocytosis, transcytosis, membrane trafficking, and signal transduction. Although caveolin has recently been identified in subcellular fractions from rat liver there is no clear-cut morphologic evidence for the presence of prototypical caveolae on the surface of hepatocytes. In this study the presence of caveolae at the cell surface of hepatocytes was directly shown by rapid-freeze, deep-etching electron microscopy. Moreover, combined deep-etching and immunogold techniques revealed caveolin in caveolae of the dorsal membrane of primary culture hepatocytes. Using reagents that perturb membrane cholesterol and interfere with endocytosis through the caveolae, a caveolae-dependent internalization of cholera toxin B and retinol-binding protein by hepatocytes in primary culture was shown. Finally, immunocytochemical analysis of caveolin in nonparenchymal cells of the rat liver showed its presence in Kupffer and stellate cells, however no caveolin could be detected in endothelial cells.

Thiopurine methyl-transferase activity and azathioprine metabolite concentrations do not predict clinical outcome in thiopurine-treated inflammatory bowel disease patients

BACKGROUND

Low thiopurine-methyl-transferase (TPMT) activity and high 6-thioguanine-nucleotide (6TGN) concentrations have been linked to therapeutic success in inflammatory bowel disease patients treated with thiopurines; however, this has not been implemented in clinical practice.

AIM

To identify a therapeutic threshold value for TPMT or 6TGN concentrations, and their capability to predict treatment safety and efficacy.

METHODS

Prospective multicentre study including steroid-resistant/dependent patients starting thiopurines. The TPMT activity was determined at inclusion (>5 U/mL required). Azathioprine metabolites [6TGN, 6-methyl-mercaptopurine ribonucleotides (6MMP), and 6TGN/6MMP and 6TGN/TPMT ratios] were periodically monitored during steroid tapering and after withdrawal for 6 months or until a new flare occurred.

RESULTS

A total of 113 patients were analysed (62% clinical response). Areas under the receiver operating characteristic (ROC) curve (AUC) relating clinical response and metabolite levels at 2, 4 and 6 months after steroid withdrawal were less than 0.7. The AUCs relating final response and initial TPMT activity or metabolite concentrations at 2, 4, 8 and 16 weeks after starting thiopurines were less than 0.7. No cut-off point with worthwhile sensitivity/specificity was found. Eight (7%) patients developed thiopurine-related toxicity that could not be linked to TPMT activity or 6TGN levels.

CONCLUSIONS

Our results do not support determination of TPMT activity or 6TGN concentrations to predict treatment outcome, and no useful serum metabolites threshold value to adjust the drug's dose was identified.

Expression of alpha-fetoprotein receptors by human T-lymphocytes during blastic transformation

Alpha-fetoprotein (AFP) and transferrin (Tf) are actively internalized by many growing cells during ontogenic and neoplastic development, including human malignant T- and B-lymphoblastoid cells. Their internalization is, on the contrary, greatly diminished or absent in mature, non-proliferating elements. In the present work, peripheral blood mononuclear cells (PBMCs) and T-lymphocytes, harvested from normal human donors, were induced to blastic transformation with phytohemagglutinin (PHA) and their ability to uptake AFP and Tf was measured and compared with Tf uptake in the same conditions. The capacity of the cells to internalize both proteins was quantified by fluorescence activated cell sorter (FACS) using fluoresceinated derivatives of these proteins. The results obtained show a significant uptake of AFP by T-lymphocytes upon PHA stimulation. The values of AFP incorporation were similar for all the cells studied (PBMCs, T-cells and T4, T8 cell subsets). The time course of AFP uptake paralleled, under the same conditions, the uptake of Tf and the expression of IL2 receptors. AFP uptake increased rapidly from the zero time (resting T-cells) and reached a maximum around 72 hr after PHA activation. Scatchard analysis of kinetic data at 4 degrees C revealed for Hu-AFP one single group of specific binding sites in PHA activated T-lymphocytes with a dissociation constant of 3.03 x 10(-7) M and around 88,000 sites/cell. There results strongly suggest the transitory expression of AFP receptors in T-lymphocytes during blastic transformation.

Spectrum of mutations in the CFTR gene in cystic fibrosis patients of Spanish ancestry

We analyzed 1,954 Spanish cystic fibrosis (CF) alleles in order to define the molecular spectrum of mutations in the CFTR gene in Spanish CF patients. Commercial panels showed a limited detection power, leading to the identification of only 76% of alleles. Two scanning techniques, denaturing gradient gel electrophoresis (DGGE) and single strand conformation polymorphism/hetroduplex (SSCP/HD), were carried out to detect CFTR sequence changes. In addition, intragenic markers IVS8CA, IVS8-6(T)n and IVS17bTA were also analyzed. Twelve mutations showed frequencies above 1%, p.F508del being the most frequent mutation (51%). We found that eighteen mutations need to be studied to achieve a detection level of 80%. Fifty-one mutations (42%) were observed once. In total, 121 disease-causing mutations were identified, accounting for 96% (1,877 out of 1,954) of CF alleles. Specific geographic distributions for the most common mutations, p.F508del, p.G542X, c.1811 + 1.6kbA > G and c.1609delCA, were confirmed. Furthermore, two other relatively common mutations (p.V232D and c.2789 + 5G > A) showed uneven geographic distributions. This updated information on the spectrum of CF mutations in Spain will be useful for improving genetic testing, as well as to facilitate counselling in people of Spanish ancestry. In addition, this study contributes to defining the molecular spectrum of CF in Europe, and corroborates the high molecular mutation heterogeneity of Mediterranean populations.