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F Parra

Publications and source records attributed to F Parra.

At least 37 records · Page 2Linked to original sources
PubMed1998

Expression of enzymatically active rabbit hemorrhagic disease virus RNA-dependent RNA polymerase in Escherichia coli.

The rabbit hemorrhagic disease virus (RHDV) (isolate AST/89) RNA-dependent RNA-polymerase (3Dpol) coding region was expressed in Escherichia coli by using a glutathione S-transferase-based vector, which allowed milligram purification of a homogeneous enzyme with an expected molecular mass of about 58 kDa. The recombinant polypeptide exhibited rifampin- and actinomycin D-resistant, poly(A)-dependent poly(U) polymerase. The enzyme also showed RNA polymerase activity in in vitro reactions with synthetic RHDV subgenomic RNA in the presence or absence of an oligo(U) primer. Template-size products were synthesized in the oligo(U)-primed reactions, whereas in the absence of added primer, RNA products up to twice the length of the template were made. The double-length RNA products were double stranded and hybridized to both positive- and negative-sense probes.

Animals↗
PubMed1998

Love styles among Guatemalans in a local village.

81 participants in a village in Guatemala were administered a translated version of the 1986 Love Attitudes Scale of Hendrick and Hendrick. Analysis showed that the men scored significantly higher on the Ludus love style than the women. Research among other Latinos outside the United States is suggested.

Adolescent↗
PubMed1997

Bactericidal effect of ADP and acetic acid on Bacillus subtilis.

Bacillus subtilis is a ubiquitous soil bacterium used for measuring the beta-lysin activity and in other bioassays. We observed a complete bactericidal effect of ADP on B. subtilis at concentrations of 50-100 microM at pH values <5.5, which disappeared at pH values above 6. The effect was also found for acetic acid at concentrations >17.4 microM and similar pH values. ATP, adenosine, and HCl were not bactericidal. We used BCECF-AM, a pH-sensitive probe, and found that the killing of B. subtilis was due to a change in the intracellular pH caused by the passage across the cell membrane of these weak organic acids when incubated with B. subtilis at pH values near the pK. More experiments are needed to determine the biological meaning of these in vitro findings.

Acetic Acid↗
PubMed1997

A single dose immunization with rabbit haemorrhagic disease virus major capsid protein produced in Saccharomyces cerevisiae induces protection.

The gene coding for the major capsid protein (VP60) from rabbit haemorrhagic disease virus was expressed in Saccharomyces cerevisiae under the phosphoglycerate kinase promoter. The recombinant VP60 produced in yeast was antigenically similar to the viral polypeptide as determined with a polyclonal serum. Electron microscopic observation of the recombinant yeast-derived antigen revealed the presence of virus-like particles similar in size and appearance to native capsids. Subcutaneous vaccination of rabbits with a single dose of this antigen in the absence of commercial adjuvants conferred complete protection against the haemorrhagic disease.

Animals↗
PubMed1996

Processing of rabbit hemorrhagic disease virus polyprotein.

Expression of rabbit hemorrhagic disease virus (RHDV) cDNAs in vitro with rabbit reticulocyte lysates and in Escherichia coli have been used to study the proteolytic processing of RHDV polyprotein encoded by ORF1. An epitope tag was used for monitoring the gene products by a specific antibody. We have identified four gene products with molecular masses of 80, 43, 73, and 60 kDa, from the amino to the carboxy terminus of the polyprotein. The amino-terminal sequences of the 43- and 73-kDa products were determined and indicated that RHDV 3C proteinase cleaved Glu-Gly peptide bonds.

Animals↗
PubMed1995

Immunogenic properties of rabbit haemorrhagic disease virus structural protein VP60 expressed by a recombinant baculovirus: an efficient vaccine.

We have constructed a recombinant baculovirus containing the gene encoding the structural protein VP60 from the Spanish field isolate AST/89 of rabbit haemorrhagic disease virus (RHDV). Infection of cultured Spodoptera frugiperda Sf9 cells with this recombinant virus resulted in the production of high yields of VP60 protein which did not seem to assemble to form virus like particles, but was antigenically similar to the corresponding viral protein obtained from purified virions. A VP60-dose study showed that the recombinant protein was able to elicit a protective response in rabbits against a nasal challenge with 100 LD50 of RHDV. The effective dose able to protect 50% of the animals in the absence of adjuvant was found to be 10-25 micrograms of recombinant VP60.

Animals↗
PubMed1995

Membrane protein molecules of transmissible gastroenteritis coronavirus also expose the carboxy-terminal region on the external surface of the virion.

The binding domains of four monoclonal antibodies (MAbs) specific for the M protein of the PUR46-MAD strain of transmissible gastroenteritis coronavirus (TGEV) have been located in the 46 carboxy-terminal amino acids of the protein by studying the binding of MAbs to recombinant M protein fragments. Immunoelectron microscopy using these MAbs demonstrated that in a significant proportion of the M protein molecules, the carboxy terminus is exposed on the external surface both in purified viruses and in nascent TGEV virions that recently exited infected swine testis cells. The same MAbs specifically neutralized the infectivity of the PUR46-MAD strain, indicating that the C-terminal domain of M protein is exposed on infectious viruses. This topology of TGEV M protein probably coexists with the structure currently described for the M protein of coronaviruses, which consists of an exposed amino terminus and an intravirion carboxy-terminal domain. The presence of a detectable number of M protein molecules with their carboxy termini exposed on the surface of the virion has relevance for viral function, since it has been shown that the carboxy terminus of M protein is immunodominant and that antibodies specific for this domain both neutralize TGEV and mediate the complement-dependent lysis of TGEV-infected cells.

Animals↗
PubMed1995

Love-styles among Latino community college students in Los Angeles.

145 Latino community college students enrolled in Chicano Studies classes in Los Angeles, California were administered a love-attitudes scale. Analysis showed that the mean scores and endorsement patterns were similar to those in earlier research on white-Latino and white-non-Latino students in the United States. Significant gender differences were found. Latino men scored more Ludic and Agapic than women. Researchers might examine the love-styles and ethnic identity in and out of marriage among Latinos, whites, and Asians in southern California.

Adolescent↗
PubMed1994

Molecular cloning, sequencing and expression in Escherichia coli of the capsid protein gene from rabbit haemorrhagic disease virus (Spanish isolate AST/89).

We describe the cloning, nucleotide sequencing and expression in Escherichia coli of the major capsid component (VP60) from the Spanish field isolate AST/89 of rabbit haemorrhagic disease virus (RHDV). The sequence of the 3'-terminal 2483 nucleotides of the genome was found to be 95.4% identical to the German RHDV strain, showing ten changes in the deduced VP60 amino acid sequence. The gene coding for this structural polypeptide has been expressed in bacteria as a beta-galactosidase fusion protein or using a T7 RNA polymerase-based system. The VP60 fusion protein showed only partial antigenic similarity with native VP60 and did not confer protective immunity. The recombinant VP60 produced in the T7 RNA polymerase-based system was antigenically similar to the viral polypeptide as determined using polyclonal and monoclonal antibodies. When used to immunize rabbits the recombinant VP60 was able to protect the animals against a lethal challenge using purified RHDV.

Animals↗
PubMed1994

Asthma and contact urticaria caused by rice in a housewife.

We report the case of an atopic housewife who presented with rhinoconjunctivitis-asthma and contact urticaria from handling rice and other cereals. She tolerated cooke cereals. Both skin prick tests with a rice extract (20% w/v) and a rub test with raw rice gave positive results. Bronchial challenge test with methacholine revealed a PC20 of 0.45 mg/ml. The challenge test with raw rice resulted in immediate and late clinical and spirometric responses; pretreatment with DSCG inhibited both responses. The histamine release test (HRT) with rice was positive, and we detected rice-specific IgE antibodies by REIA in the patient's serum. Skin prick tests, HRT, and RAST with a battery of cereals gave positive results. Finally, the rice REIA was inhibited by rice (75%), rye (63%), corn (64%), and wheat (51%) extracts.

Adult↗
PubMed1994

Love-styles among university students in Mexico.

146 university students from Mexico, representing four different majors of accounting, chemistry, philosophy and arts, and technical subjects, were administered the Sample-Profile of love-styles. Comparisons of magnitude of endorsement and rankings of six love-styles showed differential patterns of love-attitudes. Strong endorsement was found for a love-style profile characterized by a calm, deliberate, and compassionate love.

Adolescent↗
PubMed1994

Delayed allergic reaction to cefonicid.

We report a case of delayed cutaneous reaction to intramuscular treatment with cefonicid, a second generation cephalosporin. An isolated late skin test response was observed to cefonicid only and not to other beta-lactams. A patch test with cefonicid 1% was positive after 48 and 96 hours.

Cefonicid↗
PubMed1993

The amino terminal sequence of VP60 from rabbit hemorrhagic disease virus supports its putative subgenomic origin.

Direct determination of the amino acid sequence of VP60 from rabbit hemorrhagic disease virus is impeded by the presence of a blocked N-terminus. Chemical cleavage of VP60 using cyanogen bromide allowed the identification and purification of two oligopeptides showing identical amino acid composition, one of which had its amino terminus blocked. Automated sequential degradation of the unblocked CNBr- peptide yielded the amino acid sequence EGKARTAPQGEAA. This sequence is identical to the deduced amino acid sequence following the first AUG codon found at position +10 at the 5'-end of the 2.4 kb subgenomic mRNA. These data favor the hypothesis that this viral polypeptide is mainly produced from the subgenomic mRNA and not from the genomic RNA by processing of the putative polyprotein generated from the major open reading frame.

Amino Acid Sequence↗
PubMed1993

Purification and characterization of the endogenous inhibitor for proteinase B from Schizosaccharomyces pombe.

A rapid purification procedure for the endogenous inhibitor of proteinase yspB from Schizosaccharomyces pombe is described. Starting from a boiled extract, the purification procedure included an ionic exchange chromatography and two reverse phase chromatographies using a HPLC system. The molecular mass of the purified polypeptide was estimated to be 8,100 Da by gel filtration. The isoelectric point of the inhibitor was found to be 5.3 after electrofocusing of a purified preparation. The amino acid composition of the proteinase yspB inhibitor was analyzed after acid hydrolysis. The calculated number of residues was 67 and the corresponding molecular mass 7370 Da. There are several differences in the molecular characteristics between the inhibitor from Schizosaccharomyces pombe and the corresponding inhibitor previously purified from Saccharomyces cerevisiae which might reflect the evolutionary divergence between the two yeast genera.

Chromatography, High Pressure Liquid↗
PubMed1992

Cloning and sequence of a gene encoding the L7/L12 ribosomal protein equivalent of Streptomyces antibioticus.

A 50S ribosomal(r) protein from the vegetative mycelium of Streptomyces antibioticus, that is absent or modified in the spore 50S r-subunit, was purified by HPLC. Determination of its N terminus and comparison with amino acid sequence data bases indicated a strong homology with the L7/L12 r-protein from Streptomyces griseus. Screening of a cosmid library of S. antibioticus chromosomal DNA with a 20-mer oligodeoxyribonucleotide probe, corresponding to an internal region of the N terminus, allowed the isolation of two hybridizing clones. A 0.90-kb HindIII-BamHI fragment from one of these clones was sequenced and found to contain a 387-bp open reading frame. The deduced gene product shows clear homology with L7/L12 r-protein equivalent from different bacteria.

Amino Acid Sequence↗
PubMed1992

Antigenic structure of transmissible gastroenteritis virus nucleoprotein.

A group of 11 monoclonal antibodies (MAbs) raised against transmissible gastroenteritis virus (TGEV) was used to study the antigenic structure of the virus nucleoprotein (N). To identify the regions recognized by MAbs, DNA fragments derived from the N-coding region of the TGEV strain FS772/70 were cloned into pUR expression plasmids and the antigenicity of the resulting fusion proteins was analyzed by immunoblotting. A major antigenic domain was identified, covering the first 241 amino acid residues of N, within which an epitope (residues 57-117) was also found. A second antigenic domain extended from residues 175 to 360 of the nucleoprotein, within which a subsite was characterized within the region covering residues 241-349. MAb DA3 recognized a linear epitope which mapped within residues 360 and 382 at the carboxy terminus of the nucleoprotein. The binding of the majority of the MAbs (8 out of 11) to large fusions, but not to smaller fragments included in them, suggests a conformational dependence of the MAb binding sites. Our data show that the use of fusions in Western blot experiments is a useful approach to map not only linear epitopes but more complex antigenic structures found in the nucleoprotein of the TGEV.

Antibodies, Monoclonal↗