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Biomedical subjects

J Flores

Publications and source records attributed to J Flores.

At least 181 records · Page 10Linked to original sources
PubMed1983

Binding of photobilirubin to human serum albumin. Estimate of the affinity constant.

Results of experiments based upon circular dichroic spectra suggest that configurationally (Z leads to E) isomerized bilirubin (photobilirubin) binds to human serum albumin at the primary bilirubin binding site with an affinity only 2-3 times lower than that of bilirubin. The high affinity of photobilirubin for albumin, comparable to that of bilirubin, supports the roles of albumin in the stabilization and transport of the isomerized pigment in vivo and strongly suggests that albumin also functions to sequester photobilirubin effectively, reducing its toxic potential. The high affinity of photobilirubin for albumin predicts that the isomerized pigment, formed in large amounts during phototherapy for neonatal hyperbilirubinemia, should not appear in the fast-diazo-reacting ('direct') bilirubin pool nor should it interfere with nonspectroscopic bilirubin binding tests. These predictions were confirmed for the Evelyn and Malloy diazo assay for 'direct' bilirubin and a Sephadex chromatography method for assessing 'loosely bound' plasma bilirubin.

Bilirubin↗
PubMed1983

A dot hybridisation assay for detection of rotavirus.

A "dot" hybridisation technique for the detection of rotavirus in stools and other biological materials is described. The assay is based on the in-situ hybridisation of labelled single-stranded RNA probes, obtained by in-vitro transcription of rotavirus particles, to heat-denatured rotavirus RNA immobilised on nitrocellulose membranes. The method is highly specific and allows for the detection of as little as 8 pg of viral RNA. Its use for the detection of rotavirus in stool suspensions and rectal swabs obtained from children with diarrhoea may facilitate epidemiological studies of rotavirus gastroenteritis.

Child↗
PubMed1983

Drug metabolizing enzymes in Drosophila melanogaster: teratogenicity of cyclophosphamide in vitro.

This report concerns the attempt to demonstrate the practicability of using microsomal fractions (rat or Drosophila) for activating proteratogens in a Drosophila in vitro teratogen screening assay. Accordingly, a typical proteratogen (cyclophosphamide) was tested before and after microsomal activation and results compared with the drug directly on the in vitro assay. The effects of microsomal activation on known teratogens (thalidomide) and nonteratogens (acetaminophen) were also assayed in order to determine the specificity of the activation process. The results showed activation of the proteratogen into a teratogen occurred as in comparable systems. Activation was specific as teratogens and nonteratogens were not altered in the assay. These preliminary results represent the first direct demonstration that the Drosophila microsomal fraction is capable of bioactivating a proteratogen. This capability further extends the usefulness of the Drosophila embryonic culture assay as an in vitro screen for potential teratogens.

Acetaminophen↗
PubMed1983

Identification of the rotaviral gene that codes for hemagglutination and protease-enhanced plaque formation.

Temperature-sensitive mutants of bovine rotavirus, UK Compton strain, and rhesus monkey rotavirus, MMU18006 strain, were used to derive 16 reassortants by coinfection of MA104 cells. The parental viruses differed phenotypically in their neutralization specificity, their ability to hemagglutinate, and their requirement for exogenous trypsin for infectivity. When the reassortants were assayed for neutralization specificity and hemagglutination, four phenotypes were observed, indicating that these two rotaviral functions segregated independently. Protease-enhanced infectivity phenotype segregated with the HA phenotype indicating that these two functions were manifestations of the same gene product. In order to determine the gene responsible for these rotaviral functions, the reassortants were genotyped by hybridizing 32P-labeled parental transcripts and denatured reassortant genomic RNAs and analyzing the resulting hybrids by gel electrophoresis. The fourth RNA segment was clearly shown to code for HA and protease enhanced plaque formation in MA104 cells. The neutralization antigen was linked to the eighth and ninth RNA segments that comigrated during gel electrophoresis and thus could not be differentiated.

Animals↗
PubMed1983

Cytosol-membrane interface of human erythrocytes. A resonance energy transfer study.

The resonance energy transfer from donors embedded in the membrane of erythrocytes to the cytosol hemoglobin has been measured by comparing the donors' fluorescence decay in ghosts and in intact cells. A series of n - (9-anthroyloxy) stearic acids (n-AS) (n = 2, 6, 9, 12) and similar probes were used as donors, and their locations within the outer leaflet of the phospholipid bilayer were determined from their average efficiency of energy transfer, . The energy transfer data for several membrane probes were analyzed according to a simple semiempirical model, in which the heme acceptors are assumed to form a semiinfinite continuum beyond a plane, whose normal distance (d) from particular donors may be determined if the heme density in the cytosol boundary layer is known. The hemoglobin concentration in the erythrocytes was varied by suspending the cells in buffers of different ionic strengths. This made it possible to study the ionic strength dependence of the heme concentration averaged over the cell (h(c)), as well as that in the boundary layer (h(b)). Both level off above approximately 600 mosM, as does the ratio h(b)/h(c). By using the maximum heme concentration that can be obtained in osmotically shrunken cells as a limiting value, h(b) is estimated to be 17 mM or less, under physiological conditions; and from the measured for various probes, the distance d was found to range from 40 A for 2-AS to 31 A for 12-AS and 26 A for 9-vinyl anthracene (9-VA). It is concluded that the hydrophobic probe 9-VA is located near the center of the phospholipid bilayer and that the cytosol hemoglobin is in contact with the inner membrane surface, or nearly so. This conclusion is valid for oxy- and deoxy-hemoglobin, and is shown to be independent of several systematic errors that might arise from the simple assumptions of the model used. The steady-state fluorescence anisotropy of the probes was found to decrease as they approach the bilayer's central plane. The methodology developed here may be used to extend studies of cytosol membrane interactions in ghost systems to intact cells, and is useful in the investigation of the morphology of normal and pathological intact erythrocytes.

Cytosol↗
PubMed1983

Gene coding assignments for growth restriction, neutralization and subgroup specificities of the W and DS-1 strains of human rotavirus.

Gene coding assignments for growth restriction, neutralization and subgroup specificities were determined for two human rotavirus strains, DS-1 and W, which represent two distinct serotypes. The 4th gene segment of both viruses was associated with restriction of growth in cell culture. The 9th gene segment of W virus and 8th segment of DS-1 were associated with serotype specificity, while the 6th gene segment of W virus was associated with subgroup specificity.

Genes, Viral↗
PubMed1983

Expanded role of the argon laser in plastic surgery.

It has been proven that intense argon laser light is very useful in the treatment of port-wine hemangiomas and tattoos. However, lasers can successfully treat many other benign cutaneous lesions. This article reports the first use of the argon laser for granuloma faciale and hereditary hemorrhagic telangiectasia. In addition, we have also successfully treated venous lakes, senile angiomas, pyogenic granulomas, acne rosacea, and nevus of Ota.

Argon↗
PubMed1983

Serological analysis of the subgroup protein of rotavirus, using monoclonal antibodies.

Ten monoclones directed to the 42,000-dalton inner structural protein of rotavirus were analyzed. Eight monoclones reacted broadly with antigenic domains common to virtually all mammalian rotaviruses. Two monoclones had specificities similar or identical to previously characterized subgroup specificities. These subgroup monoclones were more efficient in detecting subgroup antigen than either hyperimmune or postinfection antisera. Using the subgroup monoclones, we determined that some animal as well as human rotavirus strains carry subgroup 2 specificity and that epizootic diarrhea of infant mice virus and turkey rotavirus are antigenically distinct from other mammalian rotavirus strains.

Animals↗
PubMed1983

Serological comparison of canine rotavirus with various simian and human rotaviruses by plaque reduction neutralization and hemagglutination inhibition tests.

By the plaque reduction neutralization test, the CU-1 strain of canine rotavirus was similar, if not identical, to three strains (no. 14, no. 15, and P) of the tentatively designated third human rotavirus serotype. In addition, strain CU-1 demonstrated a one-way antigenic relationship with two other strains (M and B) of the third human rotavirus serotype. The CU-1 strain of canine rotavirus hemagglutinated human group O, rhesus monkey, dog, sheep, and guinea pig erythrocytes. A two-way antigenic relationship between canine (CU-1) and simian (MMU 18006 and SA11) rotaviruses demonstrated previously by the plaque reduction neutralization test was confirmed further with two additional isolates (A79-10 and LSU 79C-36) of canine rotavirus by the plaque reduction neutralization test and the hemagglutination inhibition test. The CU-1 strain of canine rotavirus, which is known to be distinct from two well-characterized human rotavirus serotypes (Wa and DS-1), was also found to be distinct from the St. Thomas no. 4 strain, which is a newly defined fourth human rotavirus serotype. Thus, this canine strain, which is related antigenically to one of four human rotavirus serotypes, is another example of an animal rotavirus which shares serotype specificity with a human rotavirus.

Animals↗
PubMed1983

Isolation, propagation, and characterization of a second equine rotavirus serotype.

A rotavirus designated strain H-2 was isolated in primary African green monkey kidney cells from a foal with diarrhea. This cell culture-adapted strain was found to be similar, if not identical, to simian rotavirus (strains MMU18006 and SA-11) and canine rotavirus (strain CU-1) and, in addition, demonstrated a one-way antigenic relationship with five human rotavirus strains (P, B, no. 14, no. 15, and YO) of the third human rotavirus serotype by the plaque reduction neutralization test. This is the fifth example of an animal rotavirus which shares serotypic specificity with a human rotavirus. The H-2 strain is distinct from the H-1 strain (Y. Hoshino et al., J. Clin. Microbiol., in press) of equine rotavirus not only in serotypic specificity by neutralization but also in subgroup specificity, hemagglutinating activity, and RNA electrophoretic migration pattern, thus establishing the existence of a second equine rotavirus serotype. This H-2 isolate is also distinct by neutralization from three other human rotavirus serotypes, 1 (Wa), 2 (DS-1), and 4 (St. Thomas no. 4), as well as bovine (NCDV), and porcine (OSU) rotaviruses.

Animals↗
PubMed1983

Direct isolation in cell culture of human rotaviruses and their characterization into four serotypes.

Of 73 rotavirus-positive fecal specimens tested, 39 yielded a human rotavirus that could be cultivated serially in MA104 or primary African green monkey kidney cells or both; 18 were serotyped. Four distinct serotypes were identified by plaque reduction or tube neutralization assay or both, and three of these serotypes were the same as those established previously by plaque reduction, using human rotaviruses cultivated by genetic reassortment with a cultivable bovine rotavirus. Ten human rotavirus strains received from Japan were found to be similar, if not identical, to our candidate prototype strains representing these four human rotavirus serotypes.

Animals↗
PubMed1983

Isolation and characterization of an equine rotavirus.

A rotavirus, designated as the H-1 strain, was isolated from a diarrheic foal in primary African green monkey kidney cells and MA104 cells. This cell culture-adapted strain hemagglutinated erythrocytes of human group O, rhesus monkeys, guinea pigs, and sheep. It was found to be similar, if not identical, to porcine rotaviruses (strains OSU, EE, and A-580) by plaque reduction neutralization and hemagglutination inhibition tests, and, in addition, it was found to belong to subgroup 1. This equine rotavirus has an RNA electrophoretic migration pattern which was distinct from those of the three strains of porcine rotavirus. The serological relationship established by plaque reduction neutralization and hemagglutination inhibition tests between the equine (H-1) and porcine (OSU, EE, and A-580) rotaviruses is an example of a rotavirus of the same serotype being isolated from different species. The H-1 strain was distinct from four human rotavirus serotypes (Wa, DS-1, P, and St. Thomas 4) as well as from bovine rotavirus NCDV, simian rotavirus MMU18006, and canine rotavirus CU-1 by plaque reduction neutralization tests. This equine isolate (H-1) was found to be related antigenically to canine CU-1 and bovine NCDV rotaviruses in a one-way fashion by hemagglutination inhibition tests.

Animals↗
PubMed1983

Production and preliminary characterization of monoclonal antibodies directed at two surface proteins of rhesus rotavirus.

A series of monoclonal antibodies was isolated which reacted with one of two major surface proteins of rhesus rotavirus. Thirty-six monoclonal antibodies immunoprecipitated the 82-kilodalton outer capsid protein, the product of the fourth gene, the viral hemagglutinin. These monoclonal antibodies exhibited hemagglutination inhibition activity and neutralized rhesus rotavirus to moderate or high titer. Three monoclonal antibodies immunoprecipitated the 38-kilodalton outer capsid glycoprotein, the eighth or ninth gene product. These three monoclonal antibodies neutralized rhesus rotavirus to high titer and also inhibited viral hemagglutination.

Animals↗