Epidemiologic and Histopathologic Characterization of Cutaneous Metastases in Patients Who Visited 2 Hospitals in Santiago de Chile Between 2005 and 2017

BACKGROUND AND OBJECTIVE

Cutaneous metastases (CMs) account for 2% of skin tumors and their incidence varies between 0.7% and 9% in patients with cancer. The objective of this study was to describe and analyze the demographic, clinical, and histopathologic characteristics of CM in patients who visited 2 hospitals in the Santiago de Chile metropolitan region.

MATERIAL AND METHOD

We performed a retrospective, descriptive, analytical, observational, cross-sectional study. We reviewed the pathology reports, patient records, pathology slides, and dates of death for diagnosed cases of CM from the anatomic pathology departments of 2 hospitals in the Santiago de Chile metropolitan region between 2015 and 2017.

RESULTS

Ninety-six patients with CM were included in the study; 60.42% were women and 39.58% were men. The mean (SD) age was 67.95 (13.74) years, with a range of 28 to 96 years. The most common primary tumor was melanoma in 27.08% of cases (n=26), followed by breast cancer (18.75%, n=18), and adenocarcinoma (15.63%, n=15). The median time between diagnosis of the tumor and cutaneous metastasis was 9 months. Patients with CM of melanoma had a higher survival rate than patients with metastasis of other primary tumors (P<.05). A histopathologic study of 91 slides showed that diffuse infiltration of the tissue with tumor cells was the most common pattern and vascular invasion was rare.

CONCLUSIONS

The results are similar to those found worldwide. CM is a rare manifestation of internal tumors. It presents mainly at an advanced age and is equally prevalent in both sexes.

[Pyoderma gangrenosum: report of 11 cases]

BACKGROUND

Pyoderma gangrenosum is an ulcerative disease of the skin of unknown cause and generally associated to systemic illnesses. It requires an aggressive systemic therapy and there is little information about its long term evolution.

AIM

To report the clinical features of patients with pyoderma gangrenosum.

PATIENTS AND METHODS

Eleven patients (10 female) aged 27 to 81 years old with pyoderma gangrenosum are reported. All had a pathological study. Patients were followed up for a mean of 60 months.

RESULTS

The lesions were located in the lower limbs in 8 patients. Pathological study showed neutrophyl infiltrates in nine patients. Three patients had inflammatory bowel disease [corrected]. During the follow up, the disease recurred in multiple occasions, in six patients, after treatment with steroids or sulphones, and one patient has had permanently active lesions.

CONCLUSIONS

Pyoderma gangrenosum appears mostly in the lower limbs and has a high recurrence rate.

Molecular characterization of the 5' control region and of two lethal alleles affecting the hsp60 gene in Drosophila melanogaster

The chaperonins are evolutionarily conserved essential cellular proteins that help folding newly synthesized or translocated proteins, spending ATP. We present here the molecular analysis of the hsp60 gene promoter region and of two Drosophila hsp60 ethyl methane sulfonate embryonic lethal alleles that have an identical phenotype. No heat shock element sequences were found in the 5' region, supporting previous data (Kozlova, T. et al., 1997) which suggests that mitochondrial Drosophila melanogaster HSP60.1 is not heat inducible. By sequencing the lethal allele's entire open reading frame (ORF), we found a C-T transition in the hsp60F409 allele that produces a serine to leucine change, apparently distorting the protein equatorial domain structure. No changes were found in the hsp60G93 ORF. However, an analysis of the heterogeneous nuclear RNA levels showed a reduction of the hsp60 transcript in hsp60G93 flies as compared to the wild-type. These data suggest that although the defects in the hsp60 gene produced by these alleles are at different levels, both behave as null mutations.

Two roles for mu-crystallin: a lens structural protein in diurnal marsupials and a possible enzyme in mammalian retinas

PURPOSE

micro-Crystallin is a major taxon-specific lens protein in some marsupials. Like other taxon-specific crystallins, it probably has another, non-crystallin role. Here we examine the distribution of mu-crystallin among species and its localization in the eye in placental mammals. We also compare its sequence and ligand binding characteristics with those of known enzymes.

METHODS

An antibody (Mup1) was raised against a conserved 21 residue peptide of tammar wallaby mu-crystallin. This was used to detect mu-crystallin immunoreactivity in lens extracts of several species and in the tissues of rat and bovine eyes. PCR methods were used to complete the cDNA sequence of human mu-crystallin. The ability of kangaroo mu-crystallin to bind enzymatic cofactors was tested by blue-sepharose chromatography.

RESULTS

Using Mup1, abundant mu-crystallin was observed in soluble whole lens extracts of diurnal Australian marsupials. Although abundant micro-crystallin was not detectable in whole lens of nocturnal marsupials, other mammals or a bird, lower levels of immunoreactivity were detectable in lens epithelium, retinal pigment epithelium and, particularly, retina of bovine eye. In rat eye the highest levels of Mup1 reactivity were found in retinal photoreceptors. Sequence comparisons of human and kangaroo mu-crystallin reveal a superfamily relationship with enzymes of glutamate and ornithine metabolism. Co-factor binding studies indicate that mu-crystallin, like related glutamyl-tRNA reductases, binds NADPH.

CONCLUSIONS

These results suggest that mu-crystallin is a normal component of retina and other tissues which underwent gene recruitment to gain an additional structural role in the lens during the evolution of diurnal marsupial species. mu-crystallin may be an enzyme, possibly of amino acid metabolism, with particular importance for photoreceptors.

Functional and structural analysis of the sialic acid-binding domain of rotaviruses

The infectivity of most animal rotaviruses is dependent on the interaction of the virus spike protein VP4 with a sialic acid (SA)-containing cell receptor, and the SA-binding domain of this protein has been mapped between amino acids 93 and 208 of its trypsin cleavage fragment VP8. To identify which residues in this region are essential for the SA-binding activity, we performed alanine mutagenesis of the rotavirus RRV VP8 expressed in bacteria as a fusion polypeptide with glutathione S-transferase. Tyrosines were primarily targeted since tyrosine has been involved in the interaction of other viral hemagglutinins with SA. Of the 15 substitutions carried out, 10 abolished the SA-dependent hemagglutination activity of the protein, as well as its ability to bind to glycophorin A in a solid-phase assay. However, only alanine substitutions for tyrosines 155 and 188 and for serine 190 did not affect the overall conformation of the protein, as judged by their interaction with a panel of conformationally sensitive neutralizing VP8 monoclonal antibodies (MAbs). These findings suggest that these three amino acids play an essential role in the SA-binding activity of the protein, presumably by interacting directly with the SA molecule. The predicted secondary structure of VP8 suggests that it is organized as 11 beta-strands separated by loops; in this model, Tyr-155 maps to loop 7 while Tyr-188 and Ser-190 map to loop 9. The close proximity of these two loops is also supported by previous results from competition experiments with neutralizing MAbs directed at RRV VP8.

[Streptococcus pyogenes: in vitro susceptibility to several antimicrobials in two date periods]

BACKGROUND

The frequency of Streptococcus pyogenes infections with deep tissue invasion and toxic shock syndrome has increased in the last decade throughout the world.

AIM

To compare antimicrobial susceptibility of S. pyogenes strains isolated during 1986 and during 1994-95.

MATERIAL AND METHOD

Eighty two S. pyogenes strains isolated in 1986 and 67 strains isolated in 1994-95, were studied. MIC 50 and 90 were determined by and agar dilution method for penicillin, ampicillin, cefazolin, cefuroxime, erythromycin, roxithromycin and miocamycin.

RESULTS

Eighty eight strains came from skin of soft tissues, 19 from surgical wounds, 18 from invasive infections, 15 from pharyngeal swabs and 9 from other locations. All strains were susceptible to penicillin, ampicillin, cefazolin, cefuroxime, roxithromycin and miocamycin. Ninety nine percent of strains were susceptible to erythromycin. Strains isolated in 1995-95 had a higher MIC 50 and 90 for erythromycin than those isolated in 1986.

CONCLUSIONS

The changes in susceptibility to erythromycin of recently isolated strains could be due to the widespread use of macrolides in Chile.

Rhizobium tropici chromosomal citrate synthase gene

Two genes encoding citrate synthase, a key enzyme in the Krebs cycle, have been found in Rhizobium tropici. One of them is in the bacterial chromosome, while the other is in the symbiotic plasmid. We sequenced the chromosomal gene and found that it is very similar to the previously reported plasmidic gene sequence in its structural region but not in its regulatory region. The chromosomal gene is able to complement an Escherichia coli citrate synthase mutant. In R. tropici, a mutant in the chromosomal citrate synthase gene has a diminished citrate synthase activity (in free-living bacteria), a diminished nodulation capacity, and forms nitrogen-fixing nodules. In contrast, the citrate synthase double mutant forms ineffective nodules devoid of bacteroids and forms less nodules than the single chromosomal mutant. It is inferred that both genes are functional and required during the nodulation process in R. tropici.

Phylogenetic relationships and host range of Rhizobium spp. that nodulate Phaseolus vulgaris L

We determined the nucleotide sequences of 16S rRNA gene segments from five Rhizobium strains that have been isolated from tropical legume species. All share the capacity to nodulate Phaseolus vulgaris L., the common bean. Phylogenetic analysis confirmed that these strains are of two different chromosomal lineages. We defined the host ranges of two strains of Rhizobium etli and three strains of R. tropici, comparing them with those of the two most divergently related new strains. Twenty-two of the 43 tested legume species were nodulated by three or more of these strains. All seven strains have broad host ranges that include woody species such as Albizia lebbeck, Gliricidia maculata, and Leucaena leucocephala.

Genomic cloning of mouse MIF (macrophage inhibitory factor) and genetic mapping of the human and mouse expressed gene and nine mouse pseudogenes

The single functional mouse gene for MIF (macrophage migration inhibitory factor) has been cloned from a P1 library, and its exon/intron structure determined and shown to resemble that of the human gene. The gene was mapped to chromosome 10 using two multilocus crosses between laboratory strains and either Mus musculus musculus or Mus spretus. Nine additional loci containing related sequences, apparently all processed pseudogenes, were also mapped to chromosomes 1, 2, 3, 7, 8, 9, 12, 17, and 19. While most of these pseudogenes were found in inbred mice and M. spretus, some are species specific. This suggests that there have been active phases of pseudogene formation in Mus both before and after the separation of musculus and spretus. The human genome contains no pseudogenes; we assigned the human gene to chromosome 19, consistent with the location of mouse and human functional genes for MIF in a region of conserved linkage.

Reclassification of American Rhizobium leguminosarum biovar phaseoli type I strains as Rhizobium etli sp. nov

A new Rhizobium species that nodulates Phaseolus vulgaris L. is proposed on the basis of a sequence analysis of 16S ribosomal DNA. This taxon, Rhizobium etli sp. nov., was previously named Rhizobium leguminosarum biovar phaseoli (type I strains) and is characterized by the capacity to establish an effective symbiosis with bean plants, the reiteration of the nitrogenase structural genes, the organization of the common nodulation genes into two separate transcriptional units bearing nodA and nodBC, the presence of the polysaccharide inhibition gene, psi, and the 16S ribosomal DNA sequence. An analysis of the sequence of a fragment of the 16S rRNA gene shows that this gene is quite different from the gene of R. leguminosarum. In addition, all R. etli strains have identical sequences. We describe these analyses and discuss additional evidence supporting our proposal.

Rhizobium tropici, a novel species nodulating Phaseolus vulgaris L. beans and Leucaena sp. trees

A new Rhizobium species that nodulates Phaseolus vulgaris L. and Leucaena spp. is proposed on the basis of the results of multilocus enzyme electrophoresis, DNA-DNA hybridization, an analysis of ribosomal DNA organization, a sequence analysis of 16S rDNA, and an analysis of phenotypic characteristics. This taxon, Rhizobium tropici sp. nov., was previously named Rhizobium leguminosarum biovar phaseoli (type II strains) and was recognized by its host range (which includes Leucaena spp.) and nif gene organization. In contrast to R. leguminosarum biovar phaseoli, R. tropici strains tolerate high temperatures and high levels of acidity in culture and are symbiotically more stable. We identified two subgroups within R. tropici and describe them in this paper.

Genetic structure of a soil population of nonsymbiotic Rhizobium leguminosarum

The genetic structure of a population of nonsymbiotic Rhizobium leguminosarum strains was determined by the electrophoretic mobilities of eight metabolic enzymes. Nonsymbiotic strains were isolated from the rhizosphere of bean plants and characterized by growth on differential media and at different temperatures, intrinsic antibiotic resistance, the lack of homology to a nifH probe, and their inability to form nodules on bean roots. All the isolates clustered with R. leguminosarum bv. phaseoli reference strains and did not encompass any other Rhizobium taxa. Their rRNA operon restriction fragment length polymorphisms and the nucleotide sequence of a fragment of the 16S rRNA gene were also found to be identical to those of R. leguminosarum bv. phaseoli reference strains. When complemented with an R. leguminosarum bv. phaseoli symbiotic plasmid (p42d), the nonsymbiotic isolates were able to fix nitrogen in symbiosis with bean roots at levels similar to those of the parental strain. The symbiotic isolates were found at a relative frequency of 1 in 40 nonsymbiotic R. leguminosarum strains.

Genetic rearrangements of a Rhizobium phaseoli symbiotic plasmid

Different structural changes of the Sym plasmid were found in a Rhizobium phaseoli strain that loses its symbiotic phenotype at a high frequency. These rearrangements affected both nif genes and Tn5 mob insertions in the plasmid, and in some cases they modified the expression of the bacterium's nodulation ability. One of the rearrangements was more frequent in heat-treated cells, but was also found under standard culture conditions; other structural changes appeared to be related to the conjugal transfer of the plasmid.