Jose C. Rodriguez

Induction of apolipoprotein E gene expression in human and experimental atherosclerotic lesions

Hypercholesterolemia and atherosclerosis were induced in New Zealand White rabbits by cholesterol feeding. Apolipoprotein E mRNA levels in livers were found to be slightly increased, as determined by Northern blots. Apolipoprotein E gene expression was dramatically induced in rabbit atherosclerotic aortas with respect to healthy aortas. However, apolipoprotein E mRNA levels in atherosclerotic aortas were low as compared with the hepatic mRNA levels of the same animals. Interestingly, we also found a significant increase in apolipoprotein E expression in human atheromata with respect to healthy aorta from the same individual. This is the first report on apo E gene induction in human atherosclerotic lesions.

Some applications of scalar and vector fields to geometric processing of surfaces

In this paper, two geometric processing problems are considered: (1) point on a surface nearest to an external point, and (2) silhouette curve of a surface when observed from a given point. Problem (1) is solved by constructing gradient curves on the surface associated with a distance scalar field. Problem (2) appears as the intersection of surfaces (implicit case), or as tracing a plane curve (parametric case). Formulations are geometric-differential, and lead to explicit, first-order systems of ordinary differential equations (ODEs), with initial conditions that can be efficiently integrated by standard numerical methods. The methodology allows us to deal with both implicit and parametric representations, these having any functional structure for which the differential statements are meaningful.

Analysis of IncF plasmids evolution: nucleotide sequence of an IncFIII replication region.

We determined the nucleotide sequence of RepFIII, the IncFIII replication region of the plasmid pSU316. Our data confirmed that RepFIII belongs to the RepFIIA family. The comparison of the nucleotide sequences from several RepFIIA-family plasmids revealed that pSU316 and R1 replicons are almost identical (96% similarity). Most of the differences between them are clustered in the incompatibility determinant. Analysis of the rest of the sequence suggested that the divergence between R1 and pSU316 replicons is very recent.

Foam cells from aorta and spleen overexpress apolipoprotein E in the absence of hypercholesterolemia

We have studied Apo E expression in atherosclerotic lesions and spleens in rabbits after a cholesterol-rich diet is discontinued and plasma cholesterol levels return to normal values. After 16 weeks, foam cells are still present in the atherosclerotic lesions and Apo E expression persists restricted solely to the lesion as ascertained by in situ RNA hybridization and northern blot. Apo E expression is induced in spleens of hypercholesterolemic rabbits. However Apo E mRNA levels decrease in this organ parallel to the disappearance of lipid loaded macrophages. These results of in vivo studies indicate that Apo E overexpression in foam cells does not depend on high serum cholesterol levels, but is a characteristic of macrophages that have acquired the foam cell phenotype.

Isolation and evolutionary analysis of a RepFVIB replicon of the plasmid pSU212

We have isolated at least two different replication regions from pSU401, a Tn802 insertion derivative of the IncFVI plasmid pSU212. One of the replication regions (RepFVIB) is highly homologous to the RepFIIA replicon of IncFII plasmids, and thus belongs to the RepFIIA family. We have also cloned the incompatibility determinant (incFVI) and the copy number control gene (cop) from RepFVIB and determined their nucleotide sequences. The analysis of the sequences supports the idea of a modular evolution of RepFIIA plasmids.

Hypercholesterolemia induces differential expression of rabbit apolipoprotein A and C genes

We have compared steady-state mRNA levels of apolipoproteins AI, AII, AIV, CI, CII and CIII in liver and small intestine of rabbits fed on a cholesterol-rich diet for up to 16 weeks. Apolipoprotein (apo) AIV mRNA was detected in both liver and small intestine, while apo AII was not detected in either organ. Apo CI, apo CII and apo CIII were expressed only in liver and apo AI mRNA was detected only in small intestine. In small intestine, apo AIV and apo AI mRNA levels increased to a maximum at the 4th and 12th week of treatment, respectively. In liver there was a parallel increase in the mRNA levels of apo AIV, apo CI, apo CII and apo CIII, with maximum levels after 4 weeks of treatment. A 3-fold increase was found in apo CII and apo CIII hepatic transcription rates between hypercholesterolemic and control rabbits after 4 weeks of treatment, no longer detectable after 8 weeks. However, no changes were found in apo AIV and apo CI transcription rates. Changes in apolipoprotein mRNA levels were accompanied by changes in plasma lipoprotein levels. Overall, these changes correlate well with the variations detected in the expression of the different apolipoprotein genes. Our results indicate that dietary cholesterol plays an important role in the regulation of these genes and that this regulation is tissue dependent.

Characterization of the RepFVII Replicon of the Haemolytic Plasmid pSU233: Nucleotide Sequence of an incFVII Determinant

We have isolated a replication region (designated RepFVII) from the IncFVII plasmid, pSU233. Hybridization experiments showed that RepFVII has high homology to the RepFIII replicon of the plasmid pSU316 and, therefore, that pSU233 is another member of the RepFIIA family. We have also located the incompatibility gene (incFVII) from RepFVII. The analysis of its sequence revealed the same organization described for several other replicons belonging to the same family.

Incompatibility Properties of the IncFIII/FIV Haemolytic Plasmid pSU316 when Integrated in the Escherichia coli Chromosome

The haemolytic plasmid pSU316 is incompatible with members of the IncFIII and IncFIV incompatibility groups. Plasmid pSU307 (pSU316 hlyC::Tn5) was inserted by integrative suppression into the chromosome of JW112, a temperature-sensitive dnaA mutant of Escherichia coli. The incompatibility properties of this strain (SU51) were studied and it was found that: (1) plasmid pSU306 (pSU316 hlyA::Tn802) was rapidly lost from strain SU51 both at 30 degrees C and 42 degrees C; (2) the IncFIII plasmid pSU397 (ColB-K98::Tn802) was lost from strain SU51 and at 42 degrees C but not at 30 degrees C; and (3) the IncFIV plasmid R124 was stably maintained in strain SU51 at both temperatures. Revertants of pSU307 to the autonomous state could be obtained from SU51. These revertants exerted incompatibility towards the prototype plasmids pSU306, pSU397 and R124 in the same way as pSU307 itself. Thus, strain SU51 provided a suitable method for distinguishing the three different incompatibility determinants of plasmid pSU316.

Some Problems in Geometric Processing of Surfaces

This paper addresses two interesting problems in geometric processing of surfaces: (1) the determination of the curves on a surface having a constant angle with a prescribed constant direction (helical curves) and (2) the construction of the curve of contact between the surface and the cone circumscribing the surface, with its vertex at the observation point (silhouette curves). Both problems are formulated by using geometric and differential arguments leading to initial value problems of systems of explicit first-order ordinary differential equations that can be efficiently solved through standard step-by-step numerical integration methods. For each problem, the interesting cases of surfaces given in implicit and parametric form are discussed. Some illustrative examples show the good performance of the proposed methods.

Characterization and nucleotide sequence of the orif-traM-finP region of the IncFVII plasmid pSU233

SummaryBy hybridizing the IncFVII haemolytic plasmid pSU233 with a probe containing the origin of transfer of the IncFII plasmid R1, we isolated a 1.9 kb BglII fragment containing at least the origin of transfer (oriT), and the genes traM and finP. Functional complementation analysis of deletion derivatives was used to map the origin of transfer. We also determined the nucleotide sequence of traM and finP. Comparison with similar regions of several plasmids, also belonging to the RepFIIA family, revelaed that pSU233 resembles the F plasmid by very close. The homology is not evenly distributed along this region, but clustered into homologous regions (TraZb-oriT, TraMb-oriT and traM separated by non-homologous regions (TraYb-oriT, finP). This organization resembles that reported for the replication region and also suggests evolution by exchange of modules. In addition, the nucleotide sequence of finP is different from those previously described for other IncF plasmids and constitutes a new allele, which we have denominated allele VI.