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Biomedical subjects

J M Lopes

Publications and source records attributed to J M Lopes.

At least 19 recordsLinked to original sources
PubMed2002

Differential Ki67 and bcl-2 immunoexpression in solid-glandular and spindle cell components of biphasic synovial sarcoma: a double immunostaining assessment with cytokeratin and vimentin.

AIMS: Synovial sarcoma is a malignant soft tissue of uncertain histogenesis that may show a biphasic (spindle and solid/glandular components) or a monophasic histological appearance. In previous studies, we demonstrated that the solid/glandular component possesses higher proliferation rates than the spindle cell component of biphasic synovial sarcomas and that the spindle cell component may exhibit a progressive transition from or to the solid-glandular component in biphasic synovial sarcoma. To evaluate this hypothesis further, we designed a novel approach to correlate immunoexpression of Ki67, bcl-2 and bax in the spindle cell and in the solid-glandular component of biphasic synovial sarcomas. We also performed a double-immunohistochemical assessment of the Ki67 proliferative indices and the immunoexpression of anti-apoptotic protein bcl-2 in neoplastic cells expressing either vimentin or cytokeratin. METHODS AND RESULTS: Immunohistochemistry for vimentin (10 cases), bcl-2 (10 cases), Ki67(10 cases), cytokeratin (10 cases), and bax (eight cases), and double-immunostaining for vimentin/Ki67 (10 cases), vimentin/bcl-2 (nine cases), cytokeratin/Ki67 (10 cases), and cytokeratin/bcl-2 (10 cases) assays were performed in 10 cases of primary biphasic synovial sarcoma. Semiquantitative assessment was adopted for each case in both components. Statistical analysis was performed using Fisher's exact test or chi2 test. On conventional immunohistochemistry, the solid/glandular component revealed more expression of Ki67, bax and cytokeratin than the spindle cell component (P=0.0004, P=0.082, and P < 0.0001, respectively); on the other hand, the latter showed higher expression of bcl-2 and vimentin than the former (P=0.0281 and P=0.059, respectively). Double immunohistochemistry analysis revealed higher co-expression levels of cytokeratin/Ki67 and cytokeratin/bcl-2 than the spindle cell component (P=0.015 and P < 0.0001, respectively); conversely, the latter presented higher co-expression of vimentin/bcl-2 than the former (P=0.0007). All cases showed no more than 10% of cells coexpressing cytokeratin/bcl-2, cytokeratin/Ki67, and no case revealed cells coexpressing vimentin/Ki67. CONCLUSION: Our findings indicate that in biphasic synovial sarcoma the acquisition of epithelial phenotype (solid/glandular component) is associated with a high expression of pro-apoptotic proteins and a high proliferative differentiation status, and conversely, mesenchymal phenotype (spindle cell component) is associated with a high expression of apoptosis-inhibitor bcl-2 and a low proliferative terminal-type differentiation status.

Adult↗
PubMed2002

Chronic eosinophilic leukaemia presenting with erythroderma, mild eosinophilia and hyper-IgE: clinical, immunological and cytogenetic features and therapeutic approach. A case report.

A 23-year-old, white male metallurgist presented with pruritic erythematous maculo-papules over the trunk and upper limbs and 6 months later developed erythroderma, eosinophilia and multi-organ dysfunction. A diagnosis of chronic eosinophilic leukaemia was made on the basis of myeloproliferative involvement of both peripheral blood and bone marrow, associated with eosinophilic differentiation and a t(5;12)(q33;p13) translocation. The initial therapeutic approach was interferon alfa-2b plus cytosine arabinoside, for 13 months, followed by hydroxyurea plus vincristine. There was improvement of skin lesions, disappearance of eosinophilia and decrease of serum immunoglobulin E, towards normal values.

Adult↗
PubMed2001

Over-expression of the INO2 regulatory gene alters regulation of an INO1-lacZ reporter gene but does not affect regulation of INO1 expression.

The yeast INO2 gene encodes a transcriptional activator. Inositol and choline repress transcription of the INO2 gene, and its target genes. That is, INO2 transcription is auto-regulated. This observation prompted two separate investigations to determine if regulation of INO2 is required for regulation of its target genes. One study, using northern blot hybridization, showed that constitutive INO2 transcription did not affect regulation of the INO1 gene, while another study revealed that it severely dampened regulation of an INO1-lacZ gene. By repeating both assays from a single yeast strain we demonstrate that this disparity is due to the different reporter systems.

Animals↗
PubMed2001

Expression of the INO2 regulatory gene of Saccharomyces cerevisiae is controlled by positive and negative promoter elements and an upstream open reading frame.

The INO2 gene encodes a transcriptional activator of the phospholipid biosynthetic genes of Saccharomyces cerevisiae. Complete derepression of phospholipid biosynthetic gene expression in response to inositol/choline deprivation requires both INO2 and INO4. Ino2p dimerizes with Ino4p to bind the upstream activating sequence (UAS)INO element found in the promoters of the target genes. We have demonstrated previously that transcription from the INO2 promoter is autoregulated 12-fold in a manner identical to that of the target genes. Here, we show that this regulation occurs at the levels of transcription and translation. Transcription accounts for fourfold regulation, whereas translation accounts for an additional threefold regulation. Regulation of transcription requires a UAS(INO) element. Additional promoter elements include an upstream essential sequence (UES) located upstream of the UAS(INO) element and a negative regulatory element in the vicinity of the UAS(INO) element. Regulation of translation is dependent on an upstream open reading frame (uORF) in the INO2 leader. These data support the model that regulatory gene promoters may display unusual organizations and may be subject to multiple levels of regulation. We have shown previously that the UME6 gene positively regulates INO2 expression. Here, we limit the UME6-responsive region of the INO2 promoter to nucleotides -217 to -56.

Amino Acid Sequence↗
PubMed2001

Measuring beyond the microscope field of view using digital images in squamous cell carcinoma of the lip.

OBJECTIVE: To study the impact of using digital images for measuring the size of the tumors, assisting with the prognostic evaluation of carcinomas of the oral mucosa. STUDY DESIGN: The depth of invasion of 12 cases of squamous cell carcinoma of the lower lip was assessed through a microscope and through digital images. All measurements of depth of invasion were assessed in a direction orthogonal to the lip surface. First, assessment of depth of invasion was done at the microscope, using an eyepiece reticule with an engraved scale. Second, depth of invasion was assessed by digital images, using a program module developed to assist pathologists with linear measuring. When the depth of the tumor was larger than the field of view at the proper magnification, several images were taken to include the whole area of invasion. The images were finally mounted in a single image and the depth of invasion measured. RESULTS: The results show positive and negative differences between assessments when assessing depths of < 2 mm. At greater depths (> or = 2 mm), the difference was always negative, showing that for deep invasion, measurements of longer distances were always performed on digital images. CONCLUSION: Measurements with digital images beyond the field of view at proper magnification could sig nificantly alter the diagnostic and prognostic assessment made using the microscope.

Biopsy↗
PubMed2000

A network of yeast basic helix-loop-helix interactions.

The Ino4 protein belongs to the basic helix-loop-helix (bHLH) family of proteins. It is known to form a dimer with Ino2p, which regulates phospholipid biosynthetic genes. Mammalian bHLH proteins have been shown to form multiple dimer combinations. However, this flexibility in dimerization had not been documented for yeast bHLH proteins. Using the yeast two-hybrid assay and a biochemical assay we show that Ino4p dimerizes with the Pho4p, Rtg1p, Rtg3p and Sgc1p bHLH proteins. Screening a yeast cDNA library identified three additional proteins that interact with Ino4p: Bck2p, YLR422W and YNR064C. The interaction with Bck2p prompted us to examine if any of the Bck2p-associated functions affect expression of phospholipid biosynthetic genes. We found that hyperosmotic growth conditions altered the growth phase regulation of a phospholipid biosynthetic gene, CHO1. There are two recent reports of initial whole genome yeast two-hybrid interactions. Interestingly, one of these reports identified five proteins that interact with Ino4p: Ino2p, Hcs1p, Apl2p, YMR317W and YNL279W. Ino2p is the only protein in common with the data presented here. Our finding that Ino4p interacts with five bHLH proteins suggests that Ino4p is likely to be a central player in the coordination of multiple biological processes.

DNA-Binding Proteins↗
PubMed2000

Combinatorial regulation of phospholipid biosynthetic gene expression by the UME6, SIN3 and RPD3 genes.

The Ume6p-Sin3p-Rpd3p complex negatively regulates expression of genes containing a Ume6p binding site. However, these regulatory proteins also function independently to regulate gene expression both negatively and positively. The model system for this combinatorial regulation is the yeast phospholipid biosynthetic pathway. Sin3p negatively regulates the INO1, CHO1, CHO2 and OPI3 genes while Ume6p negatively regulates the INO1 gene and positively regulates the other genes. We have suggested that the positive regulation results from indirect effects on expression of the INO2 transcriptional activator gene. Here, we demonstrate that the effect of Ume6p on INO2 gene expression is also indirect. We also show that Rpd3p is a negative regulator of phospholipid biosynthetic gene expression. The ability of Ume6p, Sin3p and Rpd3p to differentially regulate expression of the phospholipid biosynthetic genes affects phospholipid composition. A sin3 mutant strain lacks detectable levels of phosphatidylethanolamine and elevated levels of phosphatidylcholine (PC) and a rpd3 mutant strain has reduced levels of PC. These alterations in membrane composition suggest that there may exist additional differences in regulation of phospholipid biosynthetic gene expression and that membrane compositions may be coordinated with other biological processes regulated by Ume6p, Sin3p and Rpd3p.

Basic Helix-Loop-Helix Proteins↗
PubMed2000

SURVEY AND SUMMARY: Saccharomyces cerevisiae basic helix-loop-helix proteins regulate diverse biological processes.

Basic helix-loop-helix (bHLH) proteins are among the most well studied and functionally important regulatory proteins in all eukaryotes. The HLH domain dictates dimerization to create homo- and heterodimers. Dimerization juxtaposes the basic regions of the two monomers to create a DNA interaction surface that recognizes the consensus sequence called the E-box, 5'-CANNTG-3'. Several bHLH proteins have been identified in the yeast Saccharomyces cerevisiae using traditional genetic methodologies. These proteins regulate diverse biological pathways. The completed sequence of the yeast genome, combined with novel methodologies allowing whole-genome expression studies, now offers a unique opportunity to study the function of these bHLH proteins. It is the purpose of this review to summarize the current knowledge of bHLH protein function in yeast.

Amino Acid Sequence↗
PubMed2000

Genetic profile of gliosarcomas.

There are distinct genetic pathways leading to the glioblastoma, the most malignant astrocytic brain tumor. Primary (de novo) glioblastomas develop in older patients and are characterized by epidermal growth factor (EGF) receptor amplification/overexpression, p16 deletion, and PTEN mutations, whereas secondary glioblastomas that progressed from low-grade or anaplastic astrocytoma develop in younger patients and frequently contain p53 mutations. In this study, we assessed the genetic profile of gliosarcoma, a rare glioblastoma variant characterized by a biphasic tissue pattern with alternating areas displaying glial and mesenchymal differentiation. Single-strand conformation polymorphism followed by direct DNA sequencing revealed p53 mutations in five of 19 gliosarcomas (26%) and PTEN mutations in seven cases (37%). Homozygous p16 deletion was detected by differential polymerase chain reaction in seven (37%) gliosarcomas. The overall incidence of alterations in the Rb pathway (p16 deletion, CDK4 amplification, or loss of pRb immunoreactivity) was 53%, and these changes were mutually exclusive. Coamplification of CDK4 and MDM2 was detected in one gliosarcoma. None of the gliosarcomas showed amplification or overexpression of the EGF receptor. Thus gliosarcomas exhibit a genetic profile similar to that of primary (de novo) glioblastomas, except for the absence of EGFR amplification/overexpression. Identical PTEN mutations in the gliomatous and sarcomatous tumor components were found in two cases. Other biopsies contained p16 deletions, an identical p53 mutation, or coamplification of MDM2 and CDK4 in both tumor areas. This strongly supports the concept of a monoclonal origin of gliosarcomas and an evolution of the sarcomatous component due to aberrant mesenchymal differentiation in a highly malignant astrocytic neoplasm.

Adult↗
PubMed2000

Effect of zeolite properties on ground-state and triplet-triplet absorption, prompt and oxygen induced delayed fluorescence of tetraphenylporphyrin at gas/solid interface.

The ground-state and transient absorption, prompt and delayed fluorescence of tetraphenylporphyrin (TPP) adsorbed onto the external surface of different zeolites was monitored using diffuse-reflectance steady-state and laser flash photolysis. The delayed fluorescence (DF) of TPP detected in the presence of O2 is attributed to the energy transfer from 3TPP to 3O2 to form 1O2 and subsequent energy transfer from 1O2 to some other 3TPP within the organised molecular ensembles on the zeolite surface. The spectroscopic and kinetic parameters, namely the yield of DF (2-20% relative to prompt fluorescence), depend on the zeolite properties: the observed differences were correlated with the acid-base properties of the two zeolite series studied in this work (KA, NaA, CaA) and (NaA, NaX, NaY).

Oxygen↗
PubMed2000

In situ corrosion control in industrial water systems.

The main objective of this study was to evaluate the efficacy of a biocide and a corrosion inhibitor against the corrosion of a circulating pipe in a cooling tower. Isothiazolone was tested as the industrial biocide. The results showed that the biocide by itself or combined with a dispersant was not efficient to control corrosion in the industrial system. Corrosion rates of 0.324 mm/year were recorded in both the presence and absence of the biocide. Corrosion control was successfully accomplished by using a corrosion inhibitor. In the latter case the maximum corrosion rate of 0.024 mm/year were obtained.

Biofilms↗
PubMed2000

The promoter of the yeast INO4 regulatory gene: a model of the simplest yeast promoter.

In Saccharomyces cerevisiae, the phospholipid biosynthetic genes are transcriptionally regulated in response to inositol and choline. This regulation requires the transcriptional activator proteins Ino4p and Ino2p, which form a heterodimer that binds to the UAS(INO) element. We have previously shown that the promoters of the INO4 and INO2 genes are among the weakest promoters characterized in yeast. Because little is known about the promoters of weakly expressed yeast genes, we report here the analysis of the constitutive INO4 promoter. Promoter deletion constructs scanning 1,000 bp upstream of the INO4 gene identified a small region (-58 to -46) that is absolutely required for expression. S1 nuclease mapping shows that this region contains the transcription start sites for the INO4 gene. An additional element (-114 to -86) modestly enhances INO4 promoter activity (fivefold). Thus, the region required for INO4 transcription is limited to 68 bp. These studies also found that INO4 gene expression is not autoregulated by Ino2p and Ino4p, despite the presence of a putative UAS(INO) element in the INO4 promoter. We further report that the INO4 steady-state transcript levels and Ino4p levels are regulated twofold in response to inositol and choline, suggesting a posttranscriptional mechanism of regulation.

Basic Helix-Loop-Helix Proteins↗
PubMed1999

Expression of GUT1, which encodes glycerol kinase in Saccharomyces cerevisiae, is controlled by the positive regulators Adr1p, Ino2p and Ino4p and the negative regulator Opi1p in a carbon source-dependent fashion.

In Saccharomyces cerevisiae glycerol utilization is mediated by two enzymes, glycerol kinase (Gut1p) and mitochondrial glycerol-3-phosphate dehydrogenase (Gut2p). The carbon source regulation of GUT1 was studied using promoter-reporter gene fusions. The promoter activity was lowest during growth on glucose and highest on the non-fermentable carbon sources, glycerol, ethanol, lactate, acetate and oleic acid. Mutational analysis of the GUT1 promoter region showed that two upstream activation sequences, UAS(INO) and UAS(ADR1), are responsible for approximately 90% of the expression during growth on glycerol. UAS(ADR1) is a presumed binding site for the zinc finger transcription factor Adr1p and UAS(INO) is a presumed binding site for the basic helix-loop-helix transcription factors Ino2p and Ino4p. In vitro experiments showed Adr1 and Ino2/Ino4 protein-dependent binding to UAS(ADR1) and UAS(INO). The negative regulator Opi1p mediates repression of the GUT1 promoter, whereas the effects of the glucose repressors Mig1p and Mig2p are minor. Together, the experiments show that GUT1 is carbon source regulated by different activation and repression systems.

Basic Helix-Loop-Helix Proteins↗
PubMed1999

Intensified phototherapy using daylight fluorescent lamps.

Jaundice is a common reason for therapeutic intervention in newborn infants and phototherapy is effective treatment if enough light energy is delivered to a skin surface area of sufficient size. Narrow spectrum blue light is superior to white light, but in developing countries fluorescent blue lamps often have to be imported and are much more expensive than white lamps. We developed a phototherapy unit in which seven daylight fluorescent tubes are placed immediately under the floor of a transparent plexiglass crib. The efficacy of this unit, delivering approximately 19 microW/cm2/nm, was compared with that of two conventional phototherapy units using overhead lamps placed 35 cm above the infants. One unit used daylight fluorescent tubes and delivered approximately 4 microW/cm2/nm, the other unit used special blue fluorescent tubes and delivered approximately 22 microW/cm2/nm. Fifty-one infants were included in the analyses, all of them breastfed on demand. Serum bilirubin levels were determined spectrophotometrically at 0, 12 and 24 h. The decrement in serum bilirubin concentrations was significantly greater in infants undergoing phototherapy with the new device or with special blue lamps compared to conventional overhead daylight lamps (p < 0.001 both at 12 and at 24 h). We conclude that highly efficient phototherapy may be delivered with daylight fluorescent lamps placed in very close proximity to the patient. Thus, lack of access to expensive imported special blue lamps does not preclude delivery of effective phototherapy in developing countries.

Circadian Rhythm↗
PubMed1999

Identification in human brain tumors of DNA sequences specific for SV40 large T antigen.

Simian virus 40 (SV40) sequences have recently been identified in a variety of human neoplasms, including mesothelioma, osteosarcoma, and brain tumors, but significant discrepancies exist regarding the frequency at which this occurs. The SV40 genome is 70% homologous to JC and BK, two related polyomaviruses that are highly prevalent in humans and which may cause in immune-compromised patients progressive multifocal leukoencephalopathy (PML) and cystitis, respectively. We have established a specific and sensitive method to identify SV40 sequence in DNA extracted from histological sections, using PCR followed by Southern hybridization to probes specific to the large T region. We found SV40 large T antigen sequences in all brain tumor types investigated. High frequencies were found in low-grade astrocytomas, anaplastic astrocytomas and secondary glioblastomas derived thereof (13/22, 59%) while somewhat lower frequencies were found in gemistocytic astrocytomas (9/28, 32%) and oligodendrogliomas (3/12, 25%). Primary glioblastomas, giant cell glioblastomas, and gliosarcomas, which clinically develop de novo, contained SV40 sequences in 11-25% of cases. Presence of viral DNA was also observed in pediatric brain tumors, including ependymomas (9/16, 56%), choroid plexus papillomas (6/16, 38%), and medulloblastomas (5/17, 29%). In 8 tumor biopsies with SV40 sequences, the adjacent normal brain tissue was also analyzed but was devoid of viral DNA in all but one case. BK and JC virus sequences were rarely detected, the overall frequencies being 3% and 2%, respectively. It remains to be shown whether the presence of SV40 contributes significantly to malignant transformation or whether certain human neoplasms provide a microenvironment that favors viral replication in humans with latent SV40 infection.

Adolescent↗
PubMed1998

Esophageal inflammatory pseudotumor associated with a pseudodiverticulosis cyst: two inter-related lesions?

There are some unusual esophageal lesions, which by their rarity, and location or etiology raise difficult therapeutic decisions for surgeons. In this report, we describe an esophageal inflammatory pseudotumor (IPT) associated with a pseudodiverticulosis cyst in an adult male. We discuss the pathogenic and the anatomopathological aspects of these uncommon associated lesions as well as the treatment of ITP.

Diverticulum, Esophageal↗