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R Bustos

Publications and source records attributed to R Bustos.

At least 19 recordsLinked to original sources
PubMed1998

Antigenic structure of human respiratory syncytial virus fusion glycoprotein.

New series of escape mutants of human respiratory syncytial virus were prepared with monoclonal antibodies specific for the fusion (F) protein. Sequence changes selected in the escape mutants identified two new antigenic sites (V and VI) recognized by neutralizing antibodies and a group-specific site (I) in the F1 chain of the F molecule. The new epitopes, and previously identified antigenic sites, were incorporated into a refined prediction of secondary-structure motifs to generate a detailed antigenic map of the F glycoprotein.

Amino Acid Sequence↗
PubMed1997

Beta-thalassemia and beta[A] globin gene haplotypes in Mexican mestizos.

B-globin haplotypes of 20 beta-thalassemia (beta-thal) and 87 beta(A) Mexican mestizo chromosomes were analyzed to ascertain the origin of the beta-thal alleles and the frequencies and distribution of the beta(A) haplotypes among northwestern Mexican mestizos. Sixteen beta-thal chromosomes carried six Mediterranean alleles [five codon 39 C-->T; two IVS1:1 G-->A; two IVS1:5 G-->A; three IVS1:110 G(A; one codon 11 (-T) and three (deltabeta)zero-thal]; the remaining four were linked to three rare alleles (two -28 A-->C and one each: -87 C-->T and initiation codon ATG-->GTG). Among the 87 beta(A) chromosomes, 17 different 5' haplotypes with frequencies for 1, 3, 2 and 5 of 39.0%, 17. 2%, 9.2% and 6.9%, respectively, were observed. The beta-haplotype analysis showed that 13 out of 16 Mediterranean chromosomes could easily be explained by gene migration; however, one codon 39 associated with haplotype 4 (----+ +-), one IVS1:1 with haplotype 1(+----++) and one IVS1:5 G-->A, may represent separate mutational events. Analysis of the rare alleles showed that the -28 A-->C mutation was associated with the commonest beta(A) haplotype in Mexican mestizos, Mediterraneans and the total world population; therefore an independent origin cannot be ruled out. The -87 C-->T and initiation codon ATG-->GTG were found with beta-haplotypes different from the reported ones, suggesting an indigenous origin.

Alleles↗
PubMed1996

Streptozotocin-induced diabetes increases fructose 2,6-biphosphate levels and glucose metabolism in thymus lymphocytes.

Acute effect of streptozotocin-induced diabetes on several parameters of glucose metabolism was investigated in thymus lymphocytes (thymocytes). The cells from diabetics rats accumulated in vitro about 2-fold more fructose 2,6-bisphosphate (Fru-2, 6-P2) in the presence of increasing glucose concentration than cells from normal rats. An increased production of lactate was also observed. Phosphofructokinase-1 (PFK-1) and phosphofructokinase-2 (PFK-2) activities were enhanced in cells from diabetic rats compared with those from normal rats. [U-14C]glucose incorporation into glycogen was also increased in cells from diabetic rats and the 14CO2 liberation was lesser than in cells from normal animals. From these data it may be concluded that the response of thymocytes to streptozotocin-induced diabetes is similar to that observed in other extrahepatic tissues.

Animals↗
PubMed1996

A point mutation in the F1 subunit of human respiratory syncytial virus fusion glycoprotein blocks its cell surface transport at an early stage of the exocytic pathway.

Vaccinia virus recombinants expressing either wild-type or mutant forms of human respiratory syncytial (RS) virus (Long strain) fusion (F) glycoprotein were obtained. Proteolytic processing of the precursor, F0, and cell surface transport of the F glycoprotein were unaffected in the recombinants, except in those that contained the replacement Phe --> Ser at position 237 of the F1 subunit. In recombinants containing this mutation, either alone or in combination with others, the traffic of the F molecule was arrested at some intermediate step of its transport to the cell surface and, consequently, the endoproteolytic cleavage of the F0 precursor was inhibited. Immunofluorescence staining of infected cells and endoglycosidase H (Endo-H) sensitivity assays indicated that the arrest occurred before the mid-Golgi compartment. Dimerization and folding of the F protein were also affected by the Phe237 --> Ser substitution. Other amino acid replacements at positions 236 or 237 of the F1 subunit had various effects upon F0 maturation. These results are discussed in terms of the maturation requirements for the RS virus F molecule.

Animals↗
PubMed1996

Mutant forms of the F protein of human respiratory syncytial (RS) virus induce a cytotoxic T lymphocyte response but not a neutralizing antibody response and only transient resistance to RS virus infection.

Vaccinia virus (vv) recombinants expressing either wild-type (VA-F) or mutant forms (VA-FT, VA-FR47, VA-FS1 to VA-FS6) of the fusion (F) protein of respiratory syncytial (RS) virus were examined for their ability to elicit antibody, cytotoxic T lymphocytes (CTL) and protection against RS virus infection in BALB/c mice. Cells infected with the VA-F and VA-FT recombinants expressed the F protein on their surface and mice vaccinated with these recombinants developed RS virus neutralizing antibodies. The VA-FR47 recombinant expressed a mutant form of the F protein (with six amino acid changes from the wild-type) in which both proteolytic processing of the F0 precursor and its transport to the cell surface were inhibited. These mutants induced transient protection against RS virus infection although they did not induce RS virus neutralizing antibodies, or antibodies detectable by ELISA. All the vv recombinants were able to induce an RS virus-specific, MHC class I restricted CTL response. Vaccination of mice with a second set of vv recombinants expressing mutant forms of the F protein showed that the replacement Phe to Ser at amino acid 237 either alone or in combination with others abolished the neutralizing antibody response but did not affect priming of CTLs. These results demonstrate that long-term protection against RS virus infection in mice vaccinated with recombinant vv expressing the F protein is more dependent upon the induction of an antibody rather than a CTL response.

Animals↗
PubMed1995

Development of highly specific monoclonal antibodies for the diagnosis of Vibrio cholerae 01.

We report here the development of two monoclonal antibodies, termed 5G8 and 5C12, belonging to the IgM and IgG1 class, respectively, suitable for the identification of Vibrio cholerae 01 in clinical and environmental samples. The specificities of the monoclonals were evaluated by ELISA and indirect immunofluorescent microscopy of microorganisms normally present in stool samples and with two bacterial panels. One panel included 72 potentially antigenically related bacterial strains and the second panel included 20 pathogenic bacterial strains involved in diarrhea cases. The results of these extensive analyses indicate that monoclonal antibodies 5G8 and 5C12 are highly specific and suitable for the clinical diagnosis of Vibrio cholerae 01 in human stool samples by indirect immunofluorescent microscopy. Although the antigenic sites recognized by these antibodies were not identified in this study, the observation of Western blot patterns suggested that 5G8 and 5C12 monoclonal antibodies bind to LPS epitopes, a good structural marker for the detection of V. cholerae 01 because it is present in all bacterial cell walls.

Animals↗
PubMed1994

Purification and characterization of the high molecule weight microtubule associated proteins from neonatal rat brain.

The changes in the levels of microtubule-associated proteins (MAPs) during advanced embryonic stages, neonatal and adult organisms reflect the importance of these cytoskeletal proteins in relation to the morphogenesis of the central nervous system. MAP-1B is found in prenatal brains and it appears to have the highest levels in neonatal rat brains, being a developmentally-regulated protein. In this research, a fast procedure to isolate MAP-1B, as well as MAP-2 and MAP-3 from neonatal rat brains was designed, based on the differential capacity of poly L-aspartic acid to release MAPs during temperature-dependent cycles of microtubule assembly in the absence of taxol. The high molecular weight MAP-1B was recovered in the warm supernatants after microtubular protein polymerization in the presence of low concentrations of polyaspartic acid. Instead, MAP-2 and a 180 kDa protein with characteristics of MAP-3 remained associated to the polymer after the assembly. Further purification of MAP-1B was attained after phosphocellulose chromatography. Isolation of MAP-2 isoforms together with MAP-3 was achieved on the basis of their selective interactions with calmodulin-agarose affinity columns. In addition, MAP-2 and MAP-3 were also purified on the basis of their capacities to interact with the tubulin peptide beta-II (422-434) derivatized on an Affigel matrix. However, MAP-1B did not interact with the beta-II tubulin fragment, but it showed interaction with the Affigel-conjugated beta-I (431-444) tubulin peptide. The different MAPs components were characterized by western blots using specific monoclonal antibodies.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

[Characterization of Neisseria meningitidis isolated fron systemic infections. Chile, 1992-1993].

BACKGROUND: in Chile, all systemic infections caused by Neisseria meningitidis must be reported and the bacterial strain must be sent to a Reference Laboratory at the Instituto de Salud Pública de Chile (ISP). AIM: to report the characterization of strains of N. meningitidis isolated during systemic infections in Chile during the years 1992 and 1993. METHODS: the serogroup, serotype, subtype and antimicrobial susceptibility of every strain of N. meningitidis received at the ISP during 1992 and 1993 was studied. RESULTS: six hundred twenty eight strains of N. meningitidis were confirmed during 1992 and 1993. B serogroup was responsible of 91.1% and 94.7% of confirmed cases during 1992 and 1993 respectively. Serotypes and subtypes most frequently associated to B serogroup were B: 15: P1.3 (63.2%) in 1992 and 51.8% in 1993) and B:NT:P1.3 (11.7% in 1992 and 21.3% in 1993). In 1992, all strains were susceptible to penicillin, chloramphenicol, ceftriaxone and rifampicin. During 1993, 7 (2%) strains were found, for the first time in Chile, moderately susceptible to penicillin and rifampicin MIC90 increased fourfold in respect of 1992, although all strains continued to be susceptible to this antimicrobial. CONCLUSIONS: the increasing frequency of NT (non typified strains) isolation will demand the use of molecular biology techniques for their identification. The appearance of penicillin resistant strains in our country is worrisome.

Chile↗
PubMed1993

Streptozotocin-induced diabetes increases fructose 2,6-bisphosphate levels and glucose metabolism in rat macrophages.

The acute effects of streptozotocin-induced diabetes on several parameters of glucose metabolism were investigated in rat peritoneal macrophages. These cells accumulated in vitro about twofold more fructose 2,6-bisphosphate in the presence of increasing glucose concentration than cells from normal rats, and an increased production of lactate was observed. Phosphofructokinase-1, phosphofructokinase-2, hexokinase, and pyruvate kinase activities were increased in cells from diabetic rats compared with those from normal rats. Transport of 2-deoxy-D-glucose was increased in cells from diabetic rats. [U-14C]Glucose incorporation into glycogen was also increased in cells from diabetics and the 14CO2 liberation was less than in cells from normal animals. Moreover, macrophages from diabetics did not possess a more active pentose phosphate pathway (measure with [1-14C]glucose oxidation) nor a greater production of superoxide anion (index of activation of macrophages) than in cells from normal animals.

Animals↗
PubMed1993

[Comparative in vitro activity of new oral macrolides against Streptococcus pyogenes strains].

Some recently introduced macrolides have several clinical advantages over erythromycin. Azithrommcin, a prototype of these new macrolides could be a good alternative for the treatment of streptococcal pharyngitis, even over penicillin, whose failure rate can be as high as 30%. The aim of this study was to evaluate the in vitro susceptibility of 120 strains of S pyogenes isolated between 1990 and 1992 (40 per year), from diverse infections (specially tonsillitis). We determined Minimal Inhibitory Concentrations (MIC) of azithromycin, clarithromycin, roxithromycin, erythromycin and penicillin using the agar dilution method and the Minimal Bactericidal Concentration (MBC) by tube dilution for azythromycin and erythromycin. The MIC 90 for the new macrolides ranged from 0.03 to 0.12 microgram/ml, and was 0.03 microgram/ml for erythromycin and penicillin (not different). All strains were susceptible to all antibiotics and the date of isolation did not influence susceptibility. The MBC for azithromycin was 0.12 microgram/ml (identical to its MIC), which demonstrates the bactericidal effect of this antibiotic. It is concluded that this in vitro data supports the potential role of these new macrolides in the treatment of streptococcal infections.

Anti-Bacterial Agents↗
PubMed1992

Stimulation of glycolysis as an activation signal in rat peritoneal macrophages. Effect of glucocorticoids on this process.

1. Peritoneal macrophages were prepared from control, Escherichia coli-treated and triamcinolone acetonide-treated rats. Control and E. coli-treated rats produced resident and activated macrophages respectively. Glycolysis in these cells was studied by the fructose 2,6-bisphosphate (Fru-2,6-P2) content, lactate release and 6-phosphofructo-1-kinase (PFK-1) and 6-phosphofructo-2-kinase (PFK-2) activities. 2. In activated macrophages, lactate release and Fru-2,6-P2 content were increased several-fold compared with those in resident cells. Moreover, the response of these parameters to phorbol 12-myristate 13-acetate in activated macrophages was greater than for resident cells. 3. PFK-2 activity was moderately increased (about 3-fold), but PFK-1 activity was increased 5-fold in activated macrophages compared with resident cells. Partially purified preparations of PFK-1 were sensitive to Fru-2,6-P2, with K0.5 about 0.25 microM in both control and activated cells. However, the Vmax. of PFK-1 from activated cells was increased. In addition, AMP stimulated PFK-1, but the kinetic pattern was different from that described for Fru-2,6-P2. Moreover there was no difference in the stimulation by AMP of PFK-1 from resident and activated cells. 4. Fru-2,6-P2 content and lactate release in macrophages from triamcinolone acetonide-treated rats were decreased in both resident and activated cells. Also, the glucocorticoid inhibited PFK-1 and PFK-2 activities in both resident and activated macrophages. PFK-1 from triamcinolone acetonide-treated rats was not stimulated by Fru-2,6-P2, whereas the effect of AMP was unchanged. The effects of glucocorticoid seem to be specific for phagocytic cells, since the glucocorticoid treatment increased PFK-1 and PFK-2 activities in liver.

Animals↗
PubMed1989

Control of fructose 2,6-bisphosphate levels in rat macrophages by glucose and phorbol ester.

The presence of fructose 2,6-bisphosphate (Fru 2,6-P2) in elicited peritoneal macrophages of rat was examined. These cells possess an active phosphofructokinase-2 which is diminished by citrate and only slightly inhibited by glycerol 3-phosphate. Phosphofructokinase-1 submaximal activity was increased 26-fold by the addition of 1 microM Fru 2,6-P2. Incubation of cells without glucose decreased the amount of Fru 2,6-P2 to zero, but further addition of 5 mM glucose increased the levels of the sugar ester 20-fold. In addition, the presence of phorbol ester potentiated the synthesis of Fru 2,6-P2. By contrast phenylisopropyladenosine or prostaglandin F2 alpha inhibited the production of Fru 2,6-P2.

Animals↗
PubMed1981

Effects of bromocriptine administration to pregnant rabbits upon fetal lung maturation.

If endogenous prolactin secretion is important in normal development of fetal lung surfactant, the inhibition of its secretion should be associated with delayed maturation of fetal lung. We therefore studied the effect of bromoergocriptine administration to pregnant rabbits upon lecithin content of fetal lung washes. The does were treated since the 27th day of gestation with either Mesilate of 2-Bromo-alpha-ergocriptine (C32H40BrN5O5, CH3SO3H) (Bromocriptine) (Parlodel, Sandoz) (1 mg/kg/day) or solvent twice daily until delivery. The newborns were killed immediately by intraperitoneal administration of sodium pentobarbital and tracheostomized; then lung washes were performed. The extracted lipids were plated and run on heat-activated thin layers of silica gel H. Lecithin was eluted, and phosphorus determination was performed. The level of lecithin phosphorus in the lung washes of the fetuses whose mothers received Bromocriptine was X = 2.24 +/- 0.39 microgram/g dry lung weight, whereas that of fetuses of control does was X = 6.93 +/- 2.64 microgram/g dry lung weight (P less than 0.001). The mean body weight of the fetuses from treated mothers was 38.22 +/- 6.39 g whereas that of fetuses from control rabbits was 47.63 +/- 6.94 g (P less than 0.001). The mother's body weight gain from days 26 to 30 in Bromocriptine-treated rabbits was 156.11 +/- 99.4 g, whereas that of controls was 374.38 +/- 166.21 g (P less than 0.01).

Animals↗