Mexico’s health system: in longstanding pursuit of universal coverage and integration

Mexico's system is dominated by corporatist, social insurance organizations governed by employer and employee trade unions in close relationship to the federal government, supplemented with government services for the uninsured, and a thriving private sector. Social insurance covers about half the population, although coverage for most is sporadic. Furthermore, these organizations have divergent service, financing, and governance structures, posing inequities and barriers in responding to beneficiary needs. Profiting from a growing capacity gap, the private sector now provides almost half of total outpatient consultations. Major public health challenges include obesity and diabetes, and social and health inequalities. Fiscal policy and improved preventive programs across institutions have had some effect on reducing health risks. Health policy has aimed towards universal coverage through coordinating government providers and strengthened public health programs. Since 2004 Seguro Popular had made progress toward universal health coverage, protecting about 85% of the population, reducing catastrophic expenses, and increasing coverage of high-cost interventions. However, to address health care package limits, attain universal financial protection and respond to corruption, President Lopez Obrador's administration canceled Seguro Popular from 2020 and established the National Health Institute for Wellbeing (INSABI). INSABI aims to equalize benefits across the insured and uninsured and re-centralize health authority by establishing the federal government as sole funder and provider of coverage for the uninsured. The separation of funding and provision, a hallmark of Seguro Popular, was replaced with supply-side funding, following the social insurance model. While these policies have challenges, they could facilitate integrating social insurance and tax funding into a single-payer capable of increasing efficiency and continuity of care as well as achieving greater equity.

Two sodium pumps in the hepatopancreas of the intertidal euryhaline crab Neohelice granulata: biochemical characteristics and differential modulation after feeding

No study has been done on the existence, biochemical characteristics, and modulation of K+-independent ouabain-insensitive Na+ ATPase activity (the second sodium pump) in the digestive tract of intertidal euryhaline crabs and moreover on the coexistence and modulation under distinct physiological and (or) environmental conditions of different sodium pumps. We determined the occurrence, characteristics, and responses at different times (0, 1, 24, 48, and 120 h) after feeding upon distinct salinities of Na+ ATPase activity and Na+/K+ ATPase in the hepatopancreas of Neohelice granulata (Dana, 1851), which is a model species. The stimulation by Na+ under total inhibition of Na+/K+ ATPase activity revealed the occurrence of Na+ ATPase activity that was totally inhibited by 2 mmol·L–1 furosemide, exhibits Michaelis–Menten kinetics for ATP (apparent Km = 0.52 ± 0.16 mmol·L–1), and highest activity at around pH 7.4. In crabs acclimated to 35 psu (osmoconforming conditions), Na+ ATPase activity was highly increased (about 15-fold) (532 ± 58 nmol Pi·mg protein−1·min−1) in the hepatopancreas 48 h after feeding. In 10 psu (hyper-regulating conditions), Na+ ATPase activity decreased in the hepatopancreas 24 h after feeding (7 ± 9 nmol Pi·mg protein−1·min−1) and recovered initial values after 48 h (24 ± 35 nmol Pi·mg protein−1·min−1). Unlike Na+ ATPase, Na+/K+ ATPase activity did not change after feeding at any salinity, suggesting the specific modulation of the second sodium pump and its role in postprandial adjustments in the hepatopancreas.

Thin-layer voltammetry of soluble species on screen-printed electrodes: proof of concept

Thin-layer diffusion conditions were accomplished on screen-printed electrodes by placing a controlled-weight onto the cast solution and allowing for its natural spreading.

In vitro surfactant and perfluorocarbon aerosol deposition in a neonatal physical model of the upper conducting airways

OBJECTIVE

Aerosol delivery holds potential to release surfactant or perfluorocarbon (PFC) to the lungs of neonates with respiratory distress syndrome with minimal airway manipulation. Nevertheless, lung deposition in neonates tends to be very low due to extremely low lung volumes, narrow airways and high respiratory rates. In the present study, the feasibility of enhancing lung deposition by intracorporeal delivery of aerosols was investigated using a physical model of neonatal conducting airways.

METHODS

The main characteristics of the surfactant and PFC aerosols produced by a nebulization system, including the distal air pressure and air flow rate, liquid flow rate and mass median aerodynamic diameter (MMAD), were measured at different driving pressures (4-7 bar). Then, a three-dimensional model of the upper conducting airways of a neonate was manufactured by rapid prototyping and a deposition study was conducted.

RESULTS

The nebulization system produced relatively large amounts of aerosol ranging between 0.3±0.0 ml/min for surfactant at a driving pressure of 4 bar, and 2.0±0.1 ml/min for distilled water (H2Od) at 6 bar, with MMADs between 2.61±0.1 µm for PFD at 7 bar and 10.18±0.4 µm for FC-75 at 6 bar. The deposition study showed that for surfactant and H2Od aerosols, the highest percentage of the aerosolized mass (∼65%) was collected beyond the third generation of branching in the airway model. The use of this delivery system in combination with continuous positive airway pressure set at 5 cmH2O only increased total airway pressure by 1.59 cmH2O at the highest driving pressure (7 bar).

CONCLUSION

This aerosol generating system has the potential to deliver relatively large amounts of surfactant and PFC beyond the third generation of branching in a neonatal airway model with minimal alteration of pre-set respiratory support.

[Multidisciplinary approach to treating life-threatening massive hemoptysis]

Massive hemoptysis is an alarming event in which asphyxiation due to aspiration of blood is the main threat. The differential diagnosis taking into consideration a wide range of potential causes is required, and in 5% to 20% of cases, the reason for bleeding is never established. Hypoxemia and rebleeding are the main life-threatening complications. We describe the case of a 68-year-old man with no relevant medical history whose massive hemoptysis and complications were treated successfully by a multidisciplinary team.

Fluoroquinolone-resistant Streptococcus agalactiae isolates from Argentina

Fluoroquinolone resistance is a growing problem that has only recently emerged in S. agalactiae. Between 2005-2007, WHONET--Argentina network evaluated levofloxacin susceptibility in 1128 clinical S. agalactiae isolates, 10 (0.9%) of which proved to be resistant. Nine of them had come from 5 hospitals (in Buenos Aires City and 4 Argentinean provinces) and recovered from urine (n=7) and vaginal screening cultures (n=2). Three strains were also resistant to macrolides, lincosamides and B streptogramins due to the ermA gene. All nine fluoroquinolone-resistant isolates bore the same two mutations, Ser79Phe in ParC and Ser81Leu in GyrA proteins. Genetic relationships were analyzed by Apal-PFGE and two clones were determined, A (n=6) and B (n=3). To our knowledge, these are the first fluoroquinolone-resistant S. agalactiae isolates detected in Latin America.

Structural organization of Bacillus subtilis phage phi29. A model

Phage phi29 is a nonisometric virus producing several types of morphological variants in normal infections. The study of these variants by electron microscopy, and their comparison with those from T-even phages, suggest that the capsid of phage phi29 is a prolate icosahedron. Phage phi29 capsid consists of a major protein, p8, and an additional protein, p8.5, making up the fibers. We have determined the number of subunits of each structural protein per viral particle taking into account the phage molecular weight (between 28 and 29.6 x 10(6)), the molecular weight of each structural protein, and the mass percentage of each protein with respect to the total protein mass of the phage. These values, together with the results obtained from chemical crosslinking of the structural proteins on the phage, suggest that the capsid contains protein p8 dimers clustered in trimers.

Immunochemical determination of gluten in malts and beers

The gluten content in different varieties of barley and malts, and in different types of beers, was determined by a 'sandwich' enzyme immunoassay (RIDASCREEN Gliadin kit). The gluten levels in barley wheat, rye and spelt malts ranged 18.8-45.0, 44.0-68.0, 41.6 and 21.2 g kg-1, respectively. When various types of beer were compared, the gluten concentration increased as follows: alcohol-free beer (<3.0), lager beers (<3.0-8.7 mg l-1), stouts (9.0-15.2 mg l-1) and wheat beers (10.6-41.2 mg l-1). When 10 Czech lager beers were analysed, using both sandwich and competitive ELISA, the results showed that the latter method provided values several times higher than the former. Gluten balance was carried out during the brewing process, starting from the raw materials and terminating at the final beer. Gluten levels decreased due to precipitation during the mashing process, primary and secondary fermentation and, lastly, as a result of adsorption during beer stabilization. The gluten content in beer is, thus, approximately three orders of magnitude lower than in the raw malt.

Biotechnological lycopene production by mated fermentation of Blakeslea trispora

A semi-industrial process (800-l fermentor) for lycopene production by mated fermentation of Blakeslea trispora plus (+) and minus (-) strains has been developed. The culture medium was designed at the flask scale, using a program based on a genetic algorithm; and a fermentation process by means of this medium was developed. Fermentation involves separate vegetative phases for (+) and (-) strains and inoculation of the production medium with a mix of both together. Feeding with imidazole or pyridine, molecules known to inhibit lycopene cyclase enzymatic activity, enhanced lycopene accumulation. Different raw materials and physical parameters, including dissolved oxygen, stirring speed, air flow rate, temperature, and pH, were checked in the fermentor to get maximum lycopene production. Typical data for the fermentation process are presented and discussed. This technology can be easily scaled-up to an industrial application for the production of this carotenoid nowadays widely in demand.

Early events of rotavirus infection: the search for the receptor(s)

The entry of rotaviruses into epithelial cells seems to be a multistep process. Infection competition experiments have suggested that at least three different interactions between the virus and cell surface molecules take place during the early events of infection, and glycolipids as well as glycoproteins have been suggested to be primary attachment receptors for rotaviruses. The infectivity of some rotavirus strains depends on the presence of sialic acid on the cell surface, however, it has been shown that this interaction is not essential, and it has been suggested that there exists a neuraminidase-resistant cell surface molecule with which most rotaviruses interact. The comparative characterization of the sialic acid-dependent rotavirus strain RRV (G3P5[3]), its neuraminidase-resistant variant nar3, and the human rotavirus strain Wa (G1P1A[8]) has allowed us to show that alpha 2 beta 1 integrin is used by nar3 as its primary cell attachment site, and by RRV in a second interaction, subsequent to its initial contact with a sialic acid-containing cell receptor. We have also shown that integrin alpha V beta 3 is used by all three rotavirus strains as a co-receptor, subsequent to their initial attachment to the cell. We propose that the functional rotavirus receptor is a complex of several cell molecules most likely immersed in glycosphingolipid-enriched plasma membrane microdomains.

A monoclonal antibody that recognizes a potential coeliac-toxic repetitive pentapeptide epitope in gliadins

OBJECTIVES

Antibodies that detect coeliac-toxic prolamins from wheat, barley and rye are important tools for controlling the diet of coeliac disease patients. Recently, a monoclonal antibody R5 that recognizes wheat gliadin, barley hordein and rye secalin equally was described. In this study, the epitope recognized by R5 was investigated.

METHODS

Both a phage-displayed heptapeptide library and overlapping peptides spanning the sequence of alpha- and gamma-type gliadins (pepscan) were screened for binding of R5.

RESULTS

Both techniques yielded comparable pentapeptide consensus sequences (phage display QXPW/FP; pepscan QQPFP). According to recent observations, this peptide stretch may be of key importance in the pathogenicity of coeliac disease. This sequence occurs repetitively in prolamins (in gamma- and omega-type prolamins more frequently than in alpha-type prolamins) together with several homologous peptide stretches, which are recognized less strongly.

CONCLUSIONS

R5 seems to be a good candidate for the specific detection of putative coeliac disease-active sequences in prolamins and thus represents a valuable tool for the quality control of gluten-free food.

Analysis and clinical effects of gluten in coeliac disease

The prolamin working group coordinates research on laboratory gluten analysis in food and on clinical evaluation of patient sensitivity to prolamins. As an observer organization to the Codex Alimentarius Commission, the group summarizes current data on analysis and effects of gluten in coeliac disease. All types of gliadin, the ethanol-soluble fraction of gluten, contain the coeliac-active factor. However, coeliac toxicity and immunogenicity (humoral and cellular) of various prolamins are not identical in coeliac patients. There are no conclusive data on the threshold of gluten sensitivity of coeliac patients. Information as to the long-term risk to coeliac patients exposed to small doses of gliadin is lacking. Therefore, every effort should be made to keep the diet of coeliac patients as gluten-free as possible. The prolamin group is currently evaluating a new enzyme-linked immunosorbent assay (ELISA) protocol for gluten analysis that could serve as a basis for further Codex regulations. The group recommends adherence to a single Codex limit for gluten-free foods. The current limit of 200 ppm gluten is questionable and requires reconsideration based on new information that will be available soon.

Receptors for insulin-like growth factor-I (IGF-I) predominate over insulin receptors in skeletal muscle throughout the life cycle of brown trout, Salmo trutta

Insulin and IGF-I binding has been studied in brown trout (Salmo trutta) wheat germ agglutinin semipurified receptors from embryos (organogenesis), larvae (yolk sac), juveniles (2.98 +/- 0.21 g bw) and adults (111.6 +/- 6.92 and 522 +/- 53 g bw). Embryos and larvae were sampled at 5 and 12 weeks after fertilization (December 1999 and February 2000) and juvenile and adults were taken simultaneously (July 1999) and under the same feeding conditions to minimize potential nutritional and seasonal effects. Insulin receptor number was maximal at 12 weeks (144 fmol/mg glycoprotein) and progressively decreased in subsequent samplings. No alterations in affinity were detected (K(d) range, 0.21-0.32 nM) and changes in number of receptor paralleled changes in total specific binding. IGF-I receptor number was highest at 5 weeks (1044 fmol/mg) and was significantly higher than values for insulin in all samplings. The affinity of IGF-I receptor did not change (K(d) range, 0.11-0.18 nM) but was consistently higher than that for the insulin receptor. A more rapid decrease of IGF-I binding and receptor number was found with age. However, the ratio of insulin/IGF-I binding established in 12-week-old larvae (0.18 +/- 0.01) was thereafter maintained at very similar values in juveniles and adults (0.15-0.17). Tyrosine kinase activity (TKA) for insulin receptors ranged between 136 and 183% and there were no significant changes with age. For the IGF-I receptor, TKA ranged from 174 to 281% and was significantly higher in 5-week-old larvae coincident with the highest levels of receptor number and declined gradually in parallel with binding levels. In conclusion, the greater abundance of IGF-I receptors during embryonic and larval development is maintained throughout juvenile and adult stages. This would suggest a key role for IGF-I in the growth and metabolism of trout muscle.

Succinylation of cyclodextrin glycosyltransferase from Thermoanaerobacter sp. 501 enhances its transferase activity using starch as donor

A simple modification procedure, the succinylation of amino groups, was suitable to increase the transferase (disproportionation) activity of cyclodextrin glycosyltransferase (CGTase) from Thermoanaerobacter sp. 501 using different linear oligosaccharides as acceptors. On the contrary, the synthesis of cyclodextrins (CDs), the coupling of CDs with oligosaccharides, and the hydrolysis of starch decreased after chemical modification. The degree of succinylation of amino groups (45%) was accurately determined by MALDI-TOF mass spectrometry. The formation of CDs under industrial conditions was analyzed for native and succinylated CGTases, showing similar selectivity to alpha-, beta-, gamma-CD. The acceptor reaction with D-glucose using soluble starch as glucosyl donor was studied at 60 degrees C and pH 5.5. Malto-oligosaccharides (MOS) production was notably higher using the semisynthetic enzyme at different ratios (w/w) starch:D-glucose. Thus, more than 90% of the initial starch was converted into MOS (G2-G7) in 48 h employing a ratio donor:acceptor 1:2 (w/w).

Identification of a type II insulin-like growth factor receptor in fish embryos

To determine whether fish have an insulin-like growth factor II/mannose 6-phosphate (IGF-II/M6-P) receptor similar to that of mammals, we have performed binding, cross-linking, and immunoprecipitation experiments with wheat-germ-agglutinin- and mannose 6-phosphate (M6-P)-affinity-purified receptor preparations from fish embryos. In both receptor preparations, IGF-II binding was specific, because labeled IGF-II could only be completely displaced by cold IGF-II but not by IGF-I or insulin. Labeled IGF-II bound to a protein with a molecular mass of approximately 250 kDa, which could be immunoprecipitated with an antibody against the rat IGF-II receptor. IGF-II stimulated tyrosine kinase activity in wheat germ agglutinin preparations and was more potent than insulin or IGF-I, but neither peptide stimulated tyrosine kinase activity in M6-P preparations. Two fish cell lines (CHSE-214 and EPC) were used to confirm the IGF-II binding data obtained in the receptor preparations, revealing the presence of highly specific IGF-II binding and the absence of insulin binding. Furthermore, a decrease of the IGF-I receptors on the cell surface did not alter IGF-II binding in EPC cells. In conclusion, we have detected the presence of IGF-II/M6-P receptors in fish embryos that are similar in structure and specificity for their ligand to those found in mammals.

Integrin alpha(v)beta(3) mediates rotavirus cell entry

Rotavirus strains differ in their need for sialic acid (SA) for initial binding to the cell surface; however, the existence of a postattachment cell receptor, common to most, if not all, rotavirus strains, has been proposed. In the present study, antibodies to the alpha(v) and beta(3) integrin subunits, and the alpha(v)beta(3) ligand, vitronectin, efficiently blocked the infectivity of the SA-dependent rhesus rotavirus RRV, its SA-independent variant nar3, and the neuraminidase-resistant human rotavirus strain Wa. Vitronectin and anti-beta(3) antibodies, however, did not block the binding of virus to cells, indicating that rotaviruses interact with alpha(v)beta(3) at a postbinding step, probably penetration. This interaction was shown to be independent of the tripeptide motif arginine-glycine-aspartic acid present in the natural ligands of this integrin. Transfection of CHO cells with alpha(v)beta(3) genes significantly increased their permissiveness to all three rotavirus strains, and the increment of virus infectivity was reverted by incubation of these cells either with antibodies to beta(3) or with vitronectin. These findings implicate alpha(v)beta(3) integrin as a cellular receptor common to neuraminidase-sensitive and neuraminidase-resistant rotaviruses, and support the hypothesis that this integrin could determine, at least in part, the cellular susceptibility to rotaviruses.

A beta-turn rich oats peptide as an antigen in an ELISA method for the screening of coeliac disease in a paediatric population

BACKGROUND

ELISA methods for the measurement of IgA antigliadin antibodies (AGA), both home-made and commercial systems, routinely employ wheat gliadin fractions as coating antigens. We investigate the sensitivity and specificity for CD diagnosis of a new ELISA method using a highly immunoreactive beta-turn rich gamma3-avenin peptide as an alternative coating antigen.

METHODS

The assay was standardized with antihuman IgA peroxidase-conjugated as the second antibody. Alternatively, an ELISA based on the use of protein A-peroxidase was assayed to measure both IgG plus IgA antibodies. Sixty-three sera from healthy controls were analyzed to establish the system's cut-off point. Sera from 103 coeliac and from 65 noncoeliac children were tested; for diagnosis purposes, a small intestinal biopsy had been performed in all of them.

RESULTS

For the IgA class antibodies assay a high sensitivity and specificity of 90.3% and 98.5%, respectively, was obtained, comparable to those achieved for IgA antiendomysium antibodies (EmA) with the same sera.

CONCLUSIONS

In view of the high sensitivity and specificity obtained together with water solubility of the peptide and easiness for large-scale reproducible synthesis, the new AGA IgA avenin peptide ELISA represents a significant improvement in CD diagnosis in comparison with conventional established AGA IgA ELISA using crude gliadins as coating antigens.

Characterization of a monoclonal antibody directed to the surface of MA104 cells that blocks the infectivity of rotaviruses

Rhesus rotavirus (RRV) binds to sialic acid residues on the surface of target cells, and treatment of these cells with neuraminidase greatly reduces virus binding with the consequent reduction of infectivity. Variants that can efficiently infect neuraminidase-treated cells have been isolated, indicating that attachment to sialic acid is not an essential step for animal rotaviruses to infect cells. To identify and characterize the neuraminidase-resistant receptor for rotaviruses, we have isolated a hybridoma that secrets a monoclonal antibody (MAb) (2D9) that specifically blocks the infectivity of wild-type (wt) RRV and of its sialic acid-independent variant nar3, in untreated as well as in neuraminidase-treated cells. The infectivity of a human rotavirus was also inhibited, although to a lesser extent. MAb 2D9 blocks the binding of the variant to MA104 cells, while not affecting the binding of wt RRV; in addition, this MAb blocked the attachment of a recombinant glutathione S-transferase (GST)-VP5 fusion protein, but did not affect the binding of GST-VP8. Altogether these results suggest that MAb 2D9 is directed to the neuraminidase-resistant receptor. This receptor seems to mediate the direct attachment of the variant to the cell, through VP5, while the receptor is used by wt RRV for a secondary interaction, after its initial binding to sialic acid, through VP8. MAb 2D9 interacts specifically with the cell surface by indirect immunofluorescence, immunoelectron microscopy, and FACS. By a solid-phase immunoisolation technique, MAb 2D9 was found to react with three proteins of ca. 47, 55, and 220 kDa, which might form a complex.

Senile dementia associated with amyloid beta protein angiopathy and tau perivascular pathology but not neuritic plaques in patients homozygous for the APOE-epsilon4 allele

Amyloid beta protein deposition in cortical and leptomeningeal vessels, causing the most common type of cerebral amyloid angiopathy, is found in sporadic and familial Alzheimer's disease (AD) and is the principal feature in the hereditary cerebral hemorrhage with amyloidosis, Dutch type. The presence of the Apolipopriotein E (APOE)-epsilon4 allele has been implicated as a risk factor for AD and the development of cerebral amyloid angiopathy in AD. We report clinical, pathological and biochemical studies on two APOE-epsilon4 homozygous subjects, who had senile dementia and whose main neuropathological feature was a severe and diffuse amyloid angiopathy associated with perivascular tau neurofibrillary pathology. Amyloid beta protein and ApoE immunoreactivity were observed in leptomeningeal vessels as well as in medium-sized and small vessels and capillaries in the parenchyma of the neocortex, hippocampus, thalamus, cerebellum, midbrain, pons, and medulla. The predominant peptide form of amyloid beta protein was that terminating at residue Val40, as determined by immunohistochemistry, amino acid sequence and mass spectrometry analysis. A crown of tau-immunopositive cell processes was consistently present around blood vessels. DNA sequence analysis of the Amyloid Precursor Protein gene and Presenilin-1 (PS-1) gene revealed no mutations. In these APOE-epsilon4 homozygous patients, the pathological process differed from that typically seen in AD in that they showed a heavy burden of perivascular tau-immunopositive cell processes associated with severe amyloid beta protein angiopathy, neurofibrillary tangles, some cortical Lewy bodies and an absence of neuritic plaques. These cases emphasize the concept that tau deposits may be pathogenetically related to amyloid beta protein deposition.

Novel procedure for the identification of proteins by mass fingerprinting combining two-dimensional electrophoresis with fluorescent SYPRO red staining

The fluorescent sensitive SYPRO Red dye was successfully employed to stain proteins in two-dimensional gels for protein identification by peptide mass fingerprinting. Proteins which are not chemically modified during the SYPRO Red staining process are well digested enzymatically in the gel and hence the resulting peptides can be efficiently eluted and analysed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). A SYPRO Red two-dimensional gel of a complex protein extract from Candida albicans was analysed by MALDI-TOF MS. The validity of SYPRO Red staining was demonstrated by identifying, via peptide mass fingerprinting, 10 different C. albicans proteins from a total of 31 selected protein spots. The peptide mass signal intensity, the number of matched peptides and the percentage of coverage of protein sequences from SYPRO Red-stained proteins were similar to or greater than those obtained in parallel with the modified silver protein gel staining. This work demonstrates that fluorescent SYPRO Red staining is compatible with the identification of proteins separated on polyacrylamide gel and that it can be used as an alternative to silver staining. As far as we know, this is the first report in which C. albicans proteins separated using 2-D gels have been identified by peptide mass fingerprinting. The improved technique described here should be very useful for carrying out proteomic studies.

Insulin and IGF-I receptors in trout adipose tissue are physiologically regulated by circulating hormone levels

In fish, insulin is believed to act on adipose tissue to promote lipid accumulation, but a direct role for insulin in fish adipose tissue lipogenesis has yet to be demonstrated. To investigate the role of insulin and insulin-like growth factor I (IGF-I) in fish adipose tissue function, we have investigated the presence and the regulation of insulin and IGF-I receptors in adipose tissue of brown trout (Salmo trutta). Receptors for insulin and IGF-I were detected in trout adipose tissue, with IGF-I receptors being more abundant (two- to tenfold) and having a higher affinity (twofold) than insulin receptors. In contrast to the situation in mammals, arginine treatment, which elevates the levels of insulin and IGF-I in plasma, increased the number of insulin receptors 1.7-fold and the number of IGF-I receptors 2.3-fold. When plasma levels of insulin and IGF-I were decreased by fasting, insulin receptor numbers fell 3.6-fold and IGF-I receptor numbers fell 2.2-fold. These results demonstrate for the first time the presence of specific insulin and IGF-I receptors in adipose tissue of ectothermic vertebrates and suggest that adipose tissue may be a target for the actions of insulin and IGF-I in fish.

[News about cancer in the press]

BACKGROUND

News on health and health care are increasingly common in the mass media, and cancer is one of the most prominent topic among these news due to its health impact.

MATERIAL AND METHODS

All news published in major newspapers in Catalonia, Spain between April to December 1996 were analysed, together with items from science and health supplements general information and science journals. Types of cancer-related topics, sources of information, the importance of cancer in the news item and the theme of the piece were analysed.

RESULTS

During the period analysed, 974 news items were published which dealt with cancer. Of these, cancer was the principal topic in 53.5% of the items published in the national press, and 63.4% of the items published in the regional press. Cancer was the subject of an editorial comment on only four occasions. The source of information was mentioned in 64.8% of the items, and mean number of sources was 1.6. Political institutions were the most frequent source of information in newspapers, while science and health supplements and other magazines tended to cite scientific and health care institutions, as well as scientific journals. Basic research was the most common topic for news (30.3%) in science and health supplements while risk and environmental factors (29.6%) were the most common topics in magazines; environmental and technological risk factors (18,6%) and conflicts with health administrative bodies (16%) were the most frequent topics in the newspapers.

CONCLUSION

News about risk factors and their prevention as well as technological and environmental factors related to cancer were among the most important topics published in the general press and magazines, together with conflicts with administrative bodies. Informations related to new therapies were a less frequent topic. Scientific journals have an important role as an information source for mass media together with political and scientific institutions.

The VP5 domain of VP4 can mediate attachment of rotaviruses to cells

Some animal rotaviruses require the presence of sialic acid (SA) on the cell surface to infect the cell. We have isolated variants of rhesus rotavirus (RRV) whose infectivity no longer depends on SA. Both the SA-dependent and -independent interactions of these viruses with the cell are mediated by the virus spike protein VP4, which is cleaved by trypsin into two domains, VP5 and VP8. In this work we have compared the binding characteristics of wild-type RRV and its variant nar3 to MA104 cells. In a direct nonradioactive binding assay, both viruses bound to the cells in a saturable and specific manner. When neutralizing monoclonal antibodies directed to both the VP8 and VP5 domains of VP4 were used to block virus binding, antibodies to VP8 blocked the cell attachment of wild-type RRV but not that of the variant nar3. Conversely, an antibody to VP5 inhibited the binding of nar3 but not that of RRV. These results suggest that while RRV binds to the cell through VP8, the variant does so through the VP5 domain of VP4. This observation was further sustained by the fact that recombinant VP8 and VP5 proteins, produced in bacteria as fusion products with glutathione S-transferase, were found to bind to MA104 cells in a specific and saturable manner and, when preincubated with the cell, were capable of inhibiting the binding of wild-type and variant viruses, respectively. In addition, the VP5 and VP8 recombinant proteins inhibited the infectivity of nar3 and RRV, respectively, confirming the results obtained in the binding assays. Interestingly, when the infectivity assay was performed on neuraminidase-treated cells, the VP5 fusion protein was also found to inhibit the infectivity of RRV, suggesting that RRV could bind to the cell through two sequential steps mediated by the interaction of VP8 and VP5 with SA-containing and SA-independent cell surface receptors, respectively.

Entry of rotaviruses is a multistep process

The infection of epithelial cells by some animal rotavirus strains requires the presence of sialic acid (SA) on the cell surface. Recently, we isolated rhesus rotavirus variants, named nar, whose infectivity, like that of human rotaviruses, is not dependent on SA. In this work, we have determined the binding properties of these SA-dependent and -independent rotavirus strains to MA104 cells. The half-time of attachment of the SA-dependent porcine rotavirus YM and reassortant virus DS1xRRV was found to be about 10 times longer in neuraminidase-treated cells than in untreated cells. On the other hand, human rotaviruses Wa and DS1, and the variant nar3, bound to cells two to three times more rapidly in the absence of SA. To investigate whether the SA-independent cellular structure recognized by the variant and human rotaviruses was the same, we used an infection assay designed to detect competition for cell surface molecules at both attachment and post-attachment steps. In this assay, human rotavirus Wa efficiently competed the infectivity of YM in untreated cells and that of the variant nar3 in untreated, as well as neuraminidase-treated, cells. This competition was nonreciprocal, since YM and nar3 did not compete, but rather increased three- to fivefold the infectivity of Wa. In contrast, a two-direction competition between the variant nar3 and DS1xRRV was found. Similar results were obtained when psoralen-inactivated viruses were used as competitors, indicating that the competition observed was during the early stages of infection. Altogether, these results suggest the existence of multiple interactions between rotaviruses and the cell surface and revealed the existence of common steps during the entry of human and animal rotavirus strains.

A novel visual immunoassay for coeliac disease screening

BACKGROUND

To date, the most commonly accepted techniques for the screening of coeliac disease are indirect immunofluorescence and enzyme-linked immunosorbent assay (ELISA), which reveal antiendomysium and antigliadin antibodies respectively. We report the use of a simple visual system for coeliac disease screening based on the use of Staphylococcus aureus protein A, which binds to both IgG and IgA, thus avoiding the need for two parallel immunoassays.

MATERIALS AND METHODS

Opaque polystyrene microwell strips coated with a wheat gliadin extract were incubated with sera followed by incubation with protein A-colloidal gold conjugate. The resulting colour was compared with that of positive and negative control sera. The procedure took less than an hour.

RESULTS

One hundred and forty-five biopsy-proven sera, 94 from active coeliac patients and 51 from non-coeliac patients with diverse gastrointestinal pathologies or diabetes mellitus, were assayed. Ninety of the 94 sera from the active coeliac patients were positive, whereas only 3 of the 51 non-coeliac control subjects were positive. The technique has a sensitivity of 95.7% and a specificity of 94.1%.

CONCLUSIONS

The sensitivity and specificity of the visual system are greater than those of most ELISA systems and are similar to those observed with IgA antiendomysium antibodies when tested in the same population. Moreover, it is inexpensive, quick, simple to perform and easy to interpret, i.e. it requires no qualified personnel. It is for these features, together with the outstanding sensitivity and specificity, that we propose this immunoassay as a new test for reliable coeliac disease screening.

[Phaeohyphomicosis by Wangiella dermatitidis in Republic Argentine.]

We are presenting the case of a 54 year-old woman, who had a kidney transplant. She came to our laboratory to consult for two cutaneous lesions: a cystic one at the back of her right leg and one localized on dorsum of left forearm. Biopsies of both lesions were performed for a histopathologic study as well as microbiological (both bacteriologic and mycologic) cultures. The histopathologic study showed a lesion compatible with a B type cutaneous lymphoma in the lesion in her leg, while in the mycologic study of the cystic lesion elements compatible with phaeohyphomycosis were observed. Development of Wangiella dermatitidis was obtained in the cultures. The cystic lesion localized on forearm was completely removed by surgery, while the lesion in the leg received oncological treatment. The aim of this paper is to describe the first published case of phaeohyphomycosis, by W. dermatitidis, in the Argentine Republic.

Insulin, insulin-like growth factor-I (IGF-I) and glucagon: the evolution of their receptors

Insulin and glucagon, two of the most studied pancreatic hormones bind to specific membrane receptors to exert their biological actions. Insulin-like growth factors IGF-I and IGF-II are structurally related to insulin, although they are expressed ubiquitously. The biological functions of the IGFs are mediated by different transmembrane receptors, which includes the insulin, IGF-I and IGF-II receptors. The interaction of insulin, insulin related peptides and glucagon with the corresponding receptors has been studied extensively in mammals and continues to be so. At the same time, research on ectothermic animals has made enormous progress in the recent years. This paper summarizes current knowledge on insulin, IGF-I and glucagon receptors, from a comparative point of view with special attention to non-mammalian vertebrates. The review covers adult and mostly typical target tissues, and with very few exceptions, developmental aspects are not considered. Binding characteristics, tissue distribution and structure of insulin and IGF-I receptors will be considered first, because both ligands and receptors are structurally related and have overlapping functions. These sections will be followed by similar distribution of information on glucagon receptors. Readers interested in either structure or functions of insulin, IGFs and glucagon in nonmammalian vertebrates are referred to other reviews (Mommsen TP, Plisetskaya EM. Insulin in fishes and agnathans: history, structure and metabolic regulation. Rev Aquat Sci 1991;4:225-259; Mommsen TP, Plisetskaya EM. Metabolic and endocrine functions of glucagon-like peptides: evolutionary and biochemical perspectives. Fish Physiol Biochem 1993;11:429-438; Duguay SJ, Mommsen TP. Molecular aspects of pancreatic peptides. In: Sherwood NM, Hew CL, editors, Fish Physiology. vol 13. 1994:225-271; Plisetskaya EM, Mommsen TP. Glucagon and glucagon-like peptides in fishes. Int Rev Citol 1996;168:187-257.).

Time resolution for visual information processing in Parkinson's disease

It has been suggested that a deficit in timing could be the cause of the sensory disturbances reported for Parkinson's disease. To test this hypothesis the temporal discrimination thresholds in four visual tasks were used to study 45 healthy young people, 14 healthy elderly people, and 17 patients with Parkinson's disease. In these tasks, subjects watched a computer controlled light emitting diode display and pushed a button when the visual event previously specified by the researcher was perceived. The time between successive images required to discriminate a visual detail was accurately quantified. In two of the four tasks, the time for visual processing of image sequences was longer in the elderly group than in the young group. No significant differences were found between patients with Parkinson's disease and their age matched controls for any of the four tasks. Present data show normal temporal discrimination and no slowing in the initial steps of visual processing in Parkinson's disease.

An innovative sandwich ELISA system based on an antibody cocktail for gluten analysis

A cocktail sandwich ELISA based on the employ of two monoclonal antibodies (MAbs) as coating antibodies and a third MAb conjugated to horseradish peroxidase has been developed for the analysis of gluten in foods. Given that each MAb displays a wide specificity spectrum for wheat, barley, rye and oats prolamins, their combination for ELISA ensures a high crossreactivity with most of the potentially toxic gliadin, hordein, secalin and avenin protein family. One of the unprecedented features of the cocktail sandwich ELISA is that it permits for the first time analysis of barley hordeins in foods, which is unattainable using conventional or commercial ELISA kits. Besides, gliadins, hordeins and secalins are recognised to the same extent. The system provides a high detection sensitivity for gliadins, hordeins, secalins and avenins (1.5, 0.05, 0.15 and 12 ng/ml, respectively). The working linear range comprises 3-100 ng/ml with a gliadin detection limit of 1.5 ppm. This limit of detection is even better than that demanded in the latest Codex recommendation, 10 ppm. Cocktail ELISA data were contrasted with those of commercial ELISA kits and confirmed by mass spectrometry, a non-immunological technique which provides evidence for the occurrence of false positive results with the commercial kits.

A new cysteine in rotavirus VP4 participates in the formation of an alternate disulfide bond

Most animal rotaviruses bind to a cell surface molecule that contains sialic acid (SA). We have recently isolated variants from simian rotavirus RRV which show an SA-independent phenotype. The VP4 protein of these variants was shown to have three amino acid changes with respect to the wt protein, one of them being Tyr-267 --> Cys. In this work, we have investigated whether the new cysteine could interfere with the disulfide bond (Cys-318/Cys-380) present in the VP5* subunit of the wt protein. Cysteine residues 318 and 380 were mutagenized in gpr8 and RRV VP4 genes, and the wt and mutant genes were transcribed and translated in vitro. The protein products were analysed by electrophoresis under reducing and non-reducing conditions. This approach showed that, in the VP4 protein synthesized in vitro, Cys-267 is capable of forming an alternate disulfide bond with Cys-318. This alternate bond also seems to occur in the VP4 protein present in the variant gpr8 virus particles.

Selective identification by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of different types of gluten in foods made with cereal mixtures

The gluten toxic fractions responsible for the mucosal damage in coeliac disease (CD), so-called gliadins, hordeins, secalins and avenins from a large number (30-40) of wheat, barley, rye and oats cultivars respectively, have been mass analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Gliadin, secalin and avenin characteristic mass profiles are nearly identical amongst distinct cultivars from the corresponding cereal, while hordeins profiles show more variability depending on the particular barley cultivar. On the basis of these four distinguishable characteristic mass patterns spreading within the 20,000-40,000 Da range, MALDI-TOF-MS has permitted the direct and simultaneous visualization of gliadins, hordeins, secalins and avenins in foods elaborated with cereal mixtures of wheat, barley, rye and oats. This capacity has been demonstrated by mass analyzing foods made with these four cereals in varying ratios. Thus MALDI-TOF-MS can be preliminarily established as a unique system with the ability to discriminate the specific type of gluten toxic fractions present in food samples.

Screening of gluten avenins in foods by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

The first procedure capable of analysing gluten avenins in gluten-free food samples aimed at the diet control of coeliac patients is described. The method is based on the direct observation of the characteristic avenin mass pattern, around 20-30 kDa, as revealed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI/TOF-MS). The mass range where avenin signals appear is free from mass peaks arising from wheat gliadin, barley hordein and rye secalin protein components, which are also toxic to coeliac patients. Therefore, avenins can easily be screened in complex formula food samples elaborated with mixtures of wheat, barley, rye and oats. In addition, a procedure to quantify avenins in food samples is described on the basis of avenin mass area measurement with a detection limit of 0.4 mg of avenins per 100 g of food.

Appearance of insulin and insulin-like growth factor-I (IGF-I) receptors throughout the ontogeny of brown trout (Salmo trutta fario)

Insulin and IGF-I receptors were characterized in glycoprotein fractions prepared by affinity chromatography from different developmental stages of brown trout. The specificity of insulin and IGF-I binding was demonstrated by crossed-competition assays: unlabelled insulin displaced bound radiolabelled insulin at concentrations 45-fold lower than unlabelled IGF-I, whilst unlabelled IGF-I displaced bound radiolabelled IGF-I at concentrations 2,000-fold lower than unlabelled insulin. The affinity of these receptors did not change significantly during trout development. Insulin-specific binding was detectable 3 weeks after spawning, after which it increased to a maximum in fry weighing 0.4 g, and decreased progressively to adult levels. IGF-I specific binding was detectable in newly laid eggs and increased to a maximum during organogenesis in eyed eggs. It then decreased progressively during subsequent stages of development to adult levels. The apparent molecular weight (Mr) of the alpha-subunit of brown trout insulin and IGF-I receptors was smaller than that of the alpha-subunit of the rat insulin receptor. Receptor tyrosine kinase activity was stimulated in a dose-dependent manner by insulin and IGF-I. Insulin and IGF-I stimulated tyrosine kinase activity and reached a maximum of 201 +/- 17.6 and 240 +/- 29.6% of basal phosphorylation, respectively.

Constitutive and inducible type 1 ribosome-inactivating proteins (RIPs) in elderberry (Sambucus nigra L.)

Two novel highly basic type 1 (single chain) ribosome-inactivating proteins (RIPs) with N-glycosidase activity have been found in elderberries (the fruits of Sambucus nigra L.). Mass spectrometry of these RIPs, which we named nigritins f1 and f2, gave Mr values of 24095 and 23 565, respectively. Both proteins strongly inhibited protein synthesis in rabbit reticulocyte lysates but were inactive against plant ribosomes. Both nigritins have a similar topological activity on pBlueScript SK+ DNA as that displayed by dianthin 30. Nigritin f1 is a constitutive RIP since it is present in both green and mature intact elderberries at nearly the same proportion with respect to total fruit protein. By contrast, nigritin f2 is inducible and only appeared in mature intact elderberries. Elderberries also contain two isoforms of a basic nigrin equivalent to the recently found basic nigrin b in elder bark (De Benito et al., FEBS Letters 413 (1997) 85-91). Our results indicate that probably not all plant RIPs exert the same biological function and that this may be determined by the physiological state of the tissue.

Beta structure motif recognition by anti-gliadin antibodies in coeliac disease

A 20-amino acid synthetic peptide from the N-terminal region of gamma3 avenin yields a surprisingly strong reactivity with anti-gliadin antibodies (AGA) of coeliac sera, comparable to that of a gliadin extract. In contrast, a low reactivity is observed with five similar peptides derived from alpha-gliadin, gamma70 and omega1 secalins. Circular dichroism studies of these peptides show that the avenin peptide displays the highest beta-turn content (30%), while other peptides yield much lower values. In agreement with circular dichroism data, nuclear magnetic resonance data point to the presence of a beta-turn in the avenin peptide DPSEQ segment, a sequence with a high statistical beta-turn preference. A strong linear dependence between AGA reactivity and beta-turn content was observed for these peptides, indicating for the first time a role of beta-turn motifs in anti-gliadin antibodies recognition in coeliac disease. This suggests that circulating AGA in coeliac patients comprise not only linear but also conformational antibodies against beta-turn motifs. Polyclonal antibodies raised against the avenin peptide containing beta-turn motifs react by immunoblotting with all gliadin, hordein and secalin proteins, which are rich in beta-turn conformations, despite that their primary structures are unrelated to that of the peptide.

Presence of polymerized and free forms of the non-toxic type 2 ribosome-inactivating protein ebulin and a structurally related new homodimeric lectin in fruits of Sambucus ebulus L

Mature leaves of dwarf elder (Sambucus ebulus L.) contain the non-toxic type 2 ribosome-inactivating protein ebulin 1 (Girbés et al., 1993b, J. Biol. Chem. 268: 18195-18199). We have now found that the green fruits of dwarf elder contain both free and polymerized forms of ebulin (ebulin f) and a new homodimeric D-galactose-binding lectin (SELfd). Polymerized material containing ebulin and lectin is composed of aggregates of variable relative molecular mass, some of them being close to 250,000. These aggregate forms are maintained in part by reducible disulphide bridges and reconstitute from reductant-free dialyzed material previously reduced with 2-mercaptoethanol. Direct incubation of free ebulin f with the free SELfd did not lead to polymerization, thus indicating that polymerization triggers some kind of substantial and perhaps catalyzed change in the structure of these proteins. Ebulin-containing polymerized material reacts with anti-ebulin f antibodies. Our results indicate that ebulin f is a fruit-form of ebulin 1. In contrast to green fruits, mature fruits lack both polymerized material and ebulin f, thus indicating some kind of reserve role for them in green fruits. Polymerization of ebulin and the dimeric lectin may represent a novel means of storing the non-toxic type 2 ribosome-inactivating proteins and lectins found in highly metabolic tissues, such as green fruits.

Astrocyte-specific expression of human T-cell lymphotropic virus type 1 (HTLV-1) Tax: induction of tumor necrosis factor alpha and susceptibility to lysis by CD8+ HTLV-1-specific cytotoxic T cells

Human T-cell lymphotropic virus type 1 (HTLV-1) is associated with a chronic neurological disease termed HTLV-1-associated myelopathy/tropical spastic paraperesis (HAM/TSP). Although the pathogenesis of this disease remains to be elucidated, the evidence suggests that immunopathological mechanisms are involved. Since HTLV-1 tax mRNA was colocalized with glial acidic fibrillary protein, a marker for astrocytes, we developed an in vitro model to assess whether HTLV-1 infection activates astrocytes to secrete cytokines or present viral immunodominant epitopes to virus-specific T cells. Two human astrocytic glioma cell lines, U251 and U373, were transfected with the 3' portion of the HTLV-1 genome and with the HTLV-1 tax gene under astrocyte-specific promoter control. In this study, we report that Tax-expressing astrocytic glioma transfectants activate the expression of tumor necrosis factor alpha mRNA in vitro. Furthermore, these Tax-expressing glioma transfectants can serve as immunological targets for HTLV-1-specific cytotoxic T lymphocytes (CTL). We propose that these events could contribute to the neuropathology of HAM/TSP, since infected astrocytes can become a source for inflammatory cytokines upon HTLV-1 infection and serve as targets for HTLV-1-specific CTL, resulting in parenchymal damage by direct lysis and/or cytokine release.

Massive glycation of protein HC, a low molecular weight lipocalin, in non-diabetic individuals

Human protein HC is a member of the lipocalin superfamily with unique properties since it carries a covalently bound fluorescent chromophore mediating the linkage of the major part of protein HC to several plasma proteins, with IgA as the dominating complex partner. Native protein HC displays characteristic absorption and fluorescence spectra similar to those of glycated proteins with advanced glycosylation end products (AGEs). In vitro glycation of protein HC induces the formation of fibril aggregates with a corresponding increase of absorption in the visible region of the spectrum. Boronate-affinity chromatography and a novel galactosyltransferase assay indicate that protein HC is modified with residues of glucose exposed in a terminal non-reducing position which is typical of glycated proteins. The glycation level of several isolated batches of protein HC as measured by both assays was around 35%, which represents the highest level described for human plasma-derived proteins from healthy individuals.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometric micro-analysis: the first non-immunological alternative attempt to quantify gluten gliadins in food samples

The first epitope-independent procedure for rapidly quantifying gluten gliadins in food by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI/TOF-MS) based on the direct observation of the characteristic gliadin mass pattern is presented. This pattern was identified in both processed and unprocessed gluten-containing food samples. The procedure allows the micro-quantification of gluten in food samples below levels toxic for coeliac patients, with a linear response in the 0.4-10 mg per 100 g range and a high detection sensitivity similar to that of enzyme-linked immunosorbent assay (ELISA) systems. Food samples simultaneously analyzed by MALDI/TOF-MS and a highly sensitive laboratory-made sandwich ELISA revealed a good correlation between the two techniques. In addition, MALDI/TOF-MS provides a rapid screening system to determine the presence of gliadins in food samples by directly monitoring the occurrence of the protonated gliadin mass pattern. The procedure also permits the study of the alteration of gliadins in food during the baking process, providing data on the heart effect by changes in protein mass signals.

Isolation and partial characterization of a novel and uncommon two-chain 64-kDa ribosome-inactivating protein from the bark of elder (Sambucus nigra L.)

A novel, strongly basic, two-chain ribosome-inactivating protein (RIP) with an apparent Mr of 64000 by SDS-PAGE and 63469 by mass spectrometry analysis, that we have named basic nigrin b, has been found in the bark of elder (Sambucus nigra L.). The new protein does not agglutinate red blood cells, even at high concentrations and displays an unusually and extremely high activity towards animal ribosomes (IC50 of 18 pg/ml for translation by rabbit reticulocyte lysates). However, it is inactive against plant and HeLa cells protein synthesis. Our functional and structural data are consistent with a heterodimeric structure for basic nigrin b of the type A-B*, B* being a truncated lectin lacking functional binding domains equivalent to the B (lectin) chain of the type 2 RIP SNA I and nigrin b present also in elder bark.

Characterization of a new non-toxic two-chain ribosome-inactivating protein and a structurally-related lectin from rhizomes of dwarf elder (Sambucus ebulus L.)

A new N-glycosidase ribosome-inactivating protein (RIP) belonging to the novel family of the nontoxic type 2 RIPs from Sambucaceae has been isolated from rhizomes of dwarf elder (Sambucus ebulus L.) and named ebulin r. Dwarf elder rhizomes also contain a novel monomeric N-Ac-galactosamine-binding lectin that we named SEAII. Ebulin r and SEAII have two isoforms each one, which were readily resolved by ion exchange. Both isoforms of ebulin (ebulins r1 and r2) strongly inhibited protein synthesis in mammalian but not in plant ribosomes by promoting depurination of sensitive ribosomes. Ebulin r and SEAII have apparent molecular masses of 56 and 33.5 kDa, respectively. Ebulins r1 and r2 are composed of two dissimilar subunits (types A-B) of apparent molecular masses of 26 and 30 kDa by disulphide bridges. The rhizome SEAII and the lectins SNA II and SNA III from elder (Sambucus nigra L.) share good amino acid sequence homology. This rhizome ebulin-A chain is more sequence-related to RIP members of cucurbitaceae than to any other plant family. The rhizome ebulin B chain shares a large homology in amino acid sequence with ebulin 1-B chain and SEAII. Anti-ebulin 1 polyclonal antibodies raised in rabbits reacted better with ebulin r1 than with ebulin r2, thus suggesting that both RIP isoforms could have some differences.