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Biomedical subjects

E Puente

Publications and source records attributed to E Puente.

13 recordsLinked to original sources
PubMed2001

Transcriptional activation of mouse sst2 somatostatin receptor promoter by transforming growth factor-beta. Involvement of Smad4.

The sst2 somatostatin receptor is an inhibitory G protein-coupled receptor, which exhibits anti-tumor properties. Expression of sst2 is lost in most human pancreatic cancers. We have cloned 2090 base pairs corresponding to the genomic DNA region upstream of the mouse sst2 (msst2) translation initiation codon (ATG). Deletion reporter analyses in mouse pituitary AtT-20 and human pancreatic cancer PANC-1, BxPC-3, and Capan-1 cells identify a region from nucleotide -260 to the ATG codon (325 base pairs) showing maximal activity, and a region between nucleotides -2025 and -260 likely to comprise silencer or transcriptional suppressor elements. In PANC-1 and AtT-20 cells, transforming growth factor (TGF)-beta up-regulates msst2 transcription. Transactivation is mediated by Smad4 and Smad3. The cis-acting region responsible for such regulation is comprised between nucleotides -1115 and -972 and includes Sp1 and CAGA-box sequences. Expression of Smad4 in Smad4-deficient Capan-1 and BxPC-3 cells restores TGF-beta-dependent and -independent msst2 transactivation. Expression of Smad4 in BxPC-3 cells reestablishes both endogenous sst2 expression and somatostatin-mediated inhibition of cell growth. These findings demonstrate that msst2 is a new target gene for TGF-beta transcription regulation and underlie the possibility that loss of Smad4 contributes to the lack of sst2 expression in human pancreatic cancer, which in turn may contribute to a stimulation of tumor growth.

5' Untranslated Regions↗
PubMed2001

Transcription of SST2 somatostatin receptor gene in human pancreatic cancer cells is altered by single nucleotide promoter polymorphism.

BACKGROUND & AIMS: The somatostatin receptor SST2 mediates the antiproliferative effect of stable somatostatin analogues. SST2 gene expression is lost in most human pancreatic carcinomas. We investigated the mechanisms that could be involved in this defect. METHODS: SST2 gene structure was investigated by sequencing and restriction fragment length polymorphism. Characterization of the polymorphism was performed by electrophoretic mobility shift, cross-linking, and transcription assays. RESULTS: No major deletion of the SST2 coding sequence was found in pancreatic carcinoma specimens, but 2 point mutations were frequently detected in the promoter sequence at positions -83 (A-->G) and -57 (C-->G) from the major transcription initiation site. These mutations were present in pancreatic cancer but also in normal pancreatic tissues or leukocytes and thus correspond to a genetic polymorphism. In the 2 human pancreatic cancer cell lines MiaPaCa-2 and AsPC-1, the naturally occurring mutation -57G had no effect on transcription of SST2 gene, whereas -83G mutation reduced it by 60%-70%. We showed that the -83G mutation creates a specific binding site for the nuclear factor I. Cotransfection experiments showed that the nuclear factor I-A1.1 isoform was responsible for SST2 promoter repression. CONCLUSIONS: The -83G polymorphism identified on human SST2 gene promoter is responsible for the specific fixation of nuclear factor I and repression of SST2 transcription in human pancreatic cancer cells. However, its contribution to pancreatic tumorigenesis remains unknown.

5' Untranslated Regions↗
PubMed2001

Neosporosis in Mexican dairy herds: lesions and immunohistochemical detection of Neospora caninum in fetuses.

Of 211 aborted bovine fetuses collected from Mexican dairy herds between January 1996 and March 1999, 73 showed microscopical lesions consistent with neosporosis. Of these 73 fetuses, 58 (79%) showed lymphocytic myocarditis, 39 (53%) showed microgliosis and multifocal necrosis in the brain, 39 (53%) showed lymphocytic hepatitis, and 19 (26%) showed lymphocytic myositis. Immunohistochemical examination of brain, myocardium and liver from 53 of the same 73 fetuses demonstrated Neospora caninum antigens in 41 (77%), of which 19 (46%) gave positive results in one of the three sites, 15 (37%) in two, and seven (17%) in three. The results indicated the presence of neosporosis in a number of the main dairy farming regions of Mexico.

Abortion, Veterinary↗
PubMed2001

Antiproliferative effect of somatostatin and analogs.

Over the past decade, antiproliferative effects of somatostatin and analogs have been reported in many somatostatin receptor-positive normal and tumor cell types. Regarding the molecular mechanisms involved, somatostatin or analogs mediate their action through both indirect and direct effects. Somatostatin acts through five somatostatin receptors (SSTR1-5) which are variably expressed in normal and tumor cells. These receptors regulate a variety of signal transduction pathways including inhibition of adenylate cyclase, regulation of ion channels, regulation of serine/threonine and tyrosine kinases and phosphatases. This review focuses on recent advances in biological mechanisms involved in the antineoplastic activity of somatostatin and analogs.

Animals↗
PubMed2001

Seroprevalence study of bovine neosporosis in Mexico.

An indirect enzyme-linked immunosorbent assay was used to obtain epidemiologic information on bovine neosporosis in dairy herds of the Mexican central plateau. Sera were collected from 1,003 cows from 50 dairy herds. Forty-three herds (group A) had been experiencing a high abortion rate. The abortion rates for the remaining 7 herds (group B) were within normal limits for Mexico. Five-hundred sixty-one (56%) of the 1,003 sera were positive. The seroprevalence of Neospora caninum antibodies was 72% (95% CI = 68-75%) in group A and 36% (95% CI = 31-40%) in group B. These results clearly show that infection with N. caninum is widespread in Mexican dairy herds, as indicated by seropositive cows in group A and group B herds at the time of the sample collection.

Animal Husbandry↗
PubMed2000

Identification of a polymorphic ryanodine receptor gene from Heliothis virescens (Lepidoptera: noctuidae).

cDNAs encoding the C-terminal 1172 amino acids of a ryanodine receptor (RyR) from the lepidopteran pest Heliothis virescens (Hv-RyR) have been cloned and characterised. Sequence comparisons, organisational studies on corresponding genomic regions and a genetic segregation analysis provide evidence for two polymorphic alleles of the Hv-RyR locus. Comparison of the Hv-RyR C-terminal amino acid sequence with equivalent regions of other RyRs reveals a high level of overall amino acid homology (74% identity with D. melanogaster and between 47.9 and 50.1% with vertebrate isoforms). Homologies are however not uniformly distributed, though regions of high and low similarity are consistent with patterns in other RyR isoforms. The structural similarity of Hv-RyR with other RyRs is also indicated by comparison of hydropathy profiles and other previously described functional domains. Such results are consistent with this region of Hv-RyR containing the Ca(2+) channel itself and being intimately involved in RyR regulation. Potential uses of the cDNAs described in the discovery and development of novel ryanodine like insecticides are discussed.

Alleles↗
PubMed2000

Somatostatin receptors.

Somatostatin is a neuropeptide produced by neuroendocrine, inflammatory and immune cells in response to different stimuli. Somatostatin inhibits various cellular functions including secretions, motility and proliferation. Its action is mediated by five specific somatostatin receptors (sst1-sst5) which belong to the G protein-coupled receptor family. The five receptors bind the natural peptide with high affinity but only sst2, sst5 and sst3 bind the short synthetic analogues used to treat patients with neuroendocrine tumors. The five receptors are expressed in various normal and tumor cells, the expression of each receptor being receptor subtype and cell-type specific. In neuroendocrine tumors, sst2 is highly expressed whereas in advanced pancreatic adenocarcinoma as well as high-grade colorectal carcinomas, its expression is lost. Each receptor subtype is coupled to different signal transduction pathways through G protein-dependent and -independent mechanisms. The synthesis of selective agonists for each receptor and the recent development of genetic animal models with selective deletion of receptor subtype provide tools for establishing some of the biological roles of the receptors. sst1, 2 and 5 mediate inhibition of GH secretion whereas sst2 and sst5 mediate inhibition of glucagon secretion and insulin secretion, respectively.

Animals↗
PubMed1998

Cloning and expression of an insect Ca(2+)-ATPase from Heliothis virescens.

A complementary DNA for the Tobacco Budworm, Heliothis virescens, sarco(endo)plasmic reticulum-type Ca(2+)-ATPase (HVSERCA) has been cloned and sequenced. cDNA fragments of adult rabbit fast-twitch muscle Ca(2+)-ATPase (SERCA1a) were used as heterologous probes to isolate a partial cDNA clone coding for a protein with high homology to the Ca(2+)-ATPase from Drosophila melanogaster (DRSERCA) and vertebrate ER/SR Ca2+ pumps. The entire cDNA clone contains an ORF encoding a protein of 1000 amino acids which shares the characteristic motifs of a P-type ATPase. HVSERCA shares 89% identity with DRSERCA, 80% identity with the Artemia Ca(2+)-ATPase and 72% identity with avian and mammalian SERCAs. An insect Ca(2+)-ATPase-specific polyclonal antiserum has been raised against a fusion protein containing sequence from the cytoplasmic domain of HVSERCA. Heterologous expression of the insect pump in COS-7 cells has been demonstrated by immunocytochemistry and the reticular pattern of staining is consistent with an ER localisation. However, the expressed enzyme from COS-7 cells does not appear to be active.

Amino Acid Sequence↗
PubMed1993

A retrospective evaluation of 193 patients with oral lichen planus.

One hundred and ninety-three patients with oral lichen planus were evaluated retrospectively. Women outnumbered men by more than two to one. The mean age at lesion discovery was in the sixth decade. The buccal mucosa was the most common site of occurrence. There were concomitant systemic diseases in many of the patients. The ulcerative form was the most prevalent referred form. Therapies included observation and treatment with topical and systemic corticosteroids with and without anti-fungals and immunosuppressants. Areas of discussion include lesion location, chronicity, therapeutic modalities, malignant transformation, age, gender, symptomatology and systemic disease.

Adult↗
PubMed1992

Isolation of putative voltage-gated epithelial K-channel isoforms from rabbit kidney and LLC-PK1 cells.

Epithelial voltage-gated potassium (K) channels have been well studied using electrophysiological methods, but little is known about their structures. We tested the hypothesis that some of these channels belong to the Shaker gene family, which encodes voltage-gated K channels in excitable tissues. From published sequences of Shaker proteins in Drosophila, rat, and mouse brain, we chose regions that were conserved between species. Based on these protein sequences, degenerate oligonucleotides flanking the putative voltage sensor (S4) were synthesized and used as primers for the polymerase chain reaction. Five Shaker-like cDNAs were amplified from rabbit kidney cortex and three from LLC-PK1, an epithelial cell line derived from pig kidney. Each partial-length rabbit kidney cDNA is approximately 850 base pairs (bp) long. The deduced amino acid sequences contain five putative transmembrane segments and are 79-97% identical to two Shaker isoforms expressed in rat brain (RBK1 and RBK2). Sequence similarity is greatest in the putative transmembrane segments S1-S5. Importantly, the S4 segment, the putative voltage gate is highly conserved in all 5 cDNAs. Southern analysis of rabbit genomic DNA suggests that each isoform is encoded by a different gene. The partial length LLC-PK1 cDNAs are 450-bp long, and the deduced amino acid sequences are 77-99% identical to the rabbit cDNAs. This is, to our knowledge, the first demonstration that Shaker-like genes are expressed in renal epithelial cells. These genes most likely encode voltage-gated K channels involved in renal epithelial K transport.

Animals↗
PubMed1981

Papillary carcinoma of rete testis.

A case of a rare papillary adenocarcinoma of the rete testis (epididymis) with a solitary metastasis to a periaortic lymph node is reported. The favorable outcome over a three and one-third-year period after radical orchiectomy and retroperitoneal lymphadenectomy has been observed. We believe this is the first report of such a tumor being treated with lymphadenectomy.

Adenocarcinoma, Papillary↗
PubMed1979

Bladder involvement with lymphoma.

Two case reports of different ways lymphoma involves the bladder are presented, with a brief updating of diagnosis and management. Symptoms and cystoscopic and roentgenographic findings are discussed. While primary lymphoma of the bladder has been reported in a few instances, the disorder is generally considered a widespread lymphatic disease.

Aged↗