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Biomedical subjects

M J Sanchez

Publications and source records attributed to M J Sanchez.

15 recordsLinked to original sources
PubMed2000

Analysis of vertebrate SCL loci identifies conserved enhancers.

The SCL gene encodes a highly conserved bHLH transcription factor with a pivotal role in hemopoiesis and vasculogenesis. We have sequenced and analyzed 320 kb of genomic DNA composing the SCL loci from human, mouse, and chicken. Long-range sequence comparisons demonstrated multiple peaks of human/mouse homology, a subset of which corresponded precisely with known SCL enhancers. Comparisons between mammalian and chicken sequences identified some, but not all, SCL enhancers. Moreover, one peak of human/mouse homology (+23 region), which did not correspond to a known enhancer, showed significant homology to an analogous region of the chicken SCL locus. A transgenic Xenopus reporter assay was established and demonstrated that the +23 region contained a new neural enhancer. This combination of long-range comparative sequence analysis with a high-throughput transgenic bioassay provides a powerful strategy for identifying and characterizing developmentally important enhancers.

Amino Acid Sequence↗
PubMed1998

Transcriptional regulation of the stem cell leukemia gene by PU.1 and Elf-1.

The SCL gene, also known as tal-1, encodes a basic helix-loop-helix transcription factor that is pivotal for the normal development of all hematopoietic lineages. SCL is expressed in committed erythroid, mast, and megakaryocytic cells as well as in hematopoietic stem cells. Nothing is known about the regulation of SCL transcription in mast cells, and in other lineages GATA-1 is the only tissue-specific transcription factor recognized to regulate the SCL gene. We have therefore analyzed the molecular mechanisms underlying SCL expression in mast cells. In this paper, we demonstrate that SCL promoter 1a was regulated by GATA-1 together with Sp1 and Sp3 in a manner similar to the situation in erythroid cells. However, SCL promoter 1b was strongly active in mast cells, in marked contrast to the situation in erythroid cells. Full activity of promoter 1b was dependent on ETS and Sp1/3 motifs. Transcription factors PU.1, Elf-1, Sp1, and Sp3 were all present in mast cell extracts, bound to promoter 1b and transactivated promoter 1b reporter constructs. These data provide the first evidence that the SCL gene is a direct target for PU.1, Elf-1, and Sp3.

Animals↗
PubMed1998

Timing of intrapartum ampicillin and prevention of vertical transmission of group B streptococcus.

OBJECTIVE: To evaluate the relationship between the time elapsed from the administration of ampicillin prophylaxis to delivery and its efficacy in interrupting intrapartum transmission of group B streptococcus. METHODS: During the 12-month study period, all women who came to the Virgen de las Nieves Hospital (Granada, Spain) for delivery were screened for group B streptococcus vaginal carriage by a pigment-detection culture-based procedure. Colonized women were treated with ampicillin (2 g intravenously), and the interval between ampicillin administration and delivery was recorded. Newborns from colonized mothers also were screened to detect group B streptococcus colonization. RESULTS: During the study period, 4525 women were admitted to the hospital for delivery and screened for group B streptococcus vaginal colonization. Group B streptococcus was detected in 543 women (12%), of whom 454 gave birth vaginally to 454 liveborn infants. Intrapartum ampicillin was given to 201 of these 454 women (44%), and 10% of the newborns from mothers who received intrapartum ampicillin prophylaxis were colonized by group B streptococcus. The relationship between timing of ampicillin administration and rate of neonatal group B streptococcal transmission was as follows: less than 1 hour before delivery, 46%; 1-2 hours, 29%; 2-4 hours, 2.9%; and more than 4 hours, 1.2%. Among the 253 mothers who received no intrapartum prophylaxis, colonization was found in 120 of their newborns (47%). CONCLUSION: When the time between the start of ampicillin prophylaxis and delivery is at least 2 hours, vertical transmission of group B streptococcus is minimized.

Ampicillin↗
PubMed1997

Expression of the Ly-6E.1 (Sca-1) transgene in adult hematopoietic stem cells and the developing mouse embryo.

The mouse hematopoietic marker Sca-1, encoded by the Ly-6E.1 and Ly-6A.2 genes, has been instrumental in the enrichment and characterization of the stem cell for the adult blood system. In the studies reported here, we use Ly-6E.1 genomic fragments to direct expression of a lacZ marker transgene in vivo to study Ly-6E.1 specific regulatory elements in the hematopoietic stem cell and to localize these cells in the developing mouse embryo. We demonstrate that a region approximately 9 kb downstream from the transcriptional start site is required for the distinct, restricted expression pattern of the Ly-6E.1-lacZ transgene within adult hematopoietic stem cells and embryos. We also demonstrate that viable and functional lacZ-expressing hematopoietic stem cells can be enriched by FDG staining and flow cytometric sorting. The Ly-6E.1-lacZ-mediated enrichment of hematopoietic stem cells from adult transgenic bone marrow in combination with the temporal expression pattern of the transgene in the pro/mesonephros suggest an intraembryonic site of development for these cells in the mouse.

Animals↗
PubMed1994

Current status of natural family planning in Granada (Spain).

In Spain the use of natural family planning (NFP) is limited. In Barcelona, CODIPLAN, an NFP planning center, has offered natural methods to potential users for a number of years. In Granada and Jaén, information provided by health professionals on fertility awareness is now gaining importance. In 1989, a seminar introduced NFP in Granada; the program has been very active since. Two courses were run for teachers and for health personnel, and we took part in the practical training of providers of alternative medical care through two programs organized by the University of Granada. We also gave talks on local radio and television programs, presented updating sessions at daycare centers, and gave health education classes at primary and secondary schools. The international seminar on NFP in March, 1992 was organized jointly by the University and the City Council. The proceedings will be published by the University of Granada. In 1990, under the scientific auspices of the Natural Family Planning Department at the Zaidin Medical Center, we started a program of training and follow-up for NFP users via an on-going seminar on NFP. In Granada and Jaén, NFP methods are now available to the general population and to health personnel.

Contraception↗
PubMed1993

Adenosquamous carcinoma of the duodenum. An immunohistochemical study.

A rare adenosquamous carcinoma of the duodenum occurred in an 84-year-old woman. Histologically the neoplasm showed evidence of glandular and squamous differentiation, and both components showed malignant characteristics. Intermediate elements sharing squamous and glandular features, were found and were immunoreactive for carcinoembryonic antigen, epithelial membrane antigen and cytokeratins of both low and high molecular weight. A review of the literature and discussion about the histogenesis is included.

Adenocarcinoma↗
PubMed1991

Mechanism of inhibition of adenylate cyclase by phospholipase C-catalyzed hydrolysis of phosphatidylcholine. Involvement of a pertussis toxin-sensitive G protein and protein kinase C.

The phospholipase C-mediated hydrolysis of phosphatidylcholine has been shown recently to be activated by a number of agonists. Muscarinic receptors, which trigger various signal transduction mechanisms including inhibition of adenylate cyclase through Gi, have been shown to be potent stimulants of this novel phospholipid degradative pathway. We demonstrate here, by exogenous addition of Bacillus cereus phosphatidylcholine-hydrolyzing phospholipase C, that phosphatidylcholine breakdown mimics the ability of carbachol to inhibit adenylate cyclase. This effect is sensitive to pertussis toxin and is entirely dependent on the presence of protein kinase C. This kinase is also required for the inhibition by carbachol of adenylate cyclase. These results suggest that the activation of phosphatidylcholine breakdown by phospholipase C may play an important role linking or favoring the coupling muscarinic receptors to Gi. Results presented here also show that phospholipase C-mediated hydrolysis of phosphoinositides by exogenous addition of Bacillus thuringiensis phosphoinositide-hydrolyzing phospholipase C does not affect adenylate cyclase, despite the fact that protein kinase C is translocated to an extent similar to that produced by the hydrolysis of phosphatidylcholine. According to the results shown here, both phospholipases also differ in their ability to down-regulate protein kinase C as well as to phosphorylate p80 and to transmodulate the binding of epidermal growth factor, two well established effects of protein kinase C in Swiss 3T3 fibroblasts. This emphasizes the complexity, from a functional point of view, of protein kinase C activation "in vivo."

Adenylate Cyclase Toxin↗
PubMed1990

Recall strategies and memory for health-care visits.

Complex questions in health surveys place heavy cognitive demands on respondents, prompting researchers to appraise how specific cognitive interventions may improve the accuracy of people's answers. Investigators in one experiment asked participants to recall visits to medical providers in forward, backward, or no particular order, and matched results with providers' records. "Free" recall proved marginally superior to forward or backward ordering, although overall respondents underreported the number of visits by 20 percent; participants' gender and self-reported health status, among other factors, also affected quality of recall. The experiment lends support to contentions that the methods of cognitive science applied to survey research better the accuracy of population survey data.

Cognition↗
PubMed1985

Influence of spinal cord stimulation on peripheral blood flow.

In 27 vasculopathic and 9 nonvasculopathic patients who underwent spinal cord stimulation to treat pain in lower extremities, Doppler recordings and thermography were used to study peripheral blood flow changes during stimulation. Generally, poststimulation pain relief coincided with a improvement of Doppler recording, a normalization of morphology and increase of pulse wave amplitude, and a rise of skin temperature in the painful area.

Arterial Occlusive Diseases↗
PubMedDate not supplied

The thousand and one ways of being a T cell.

Developing T cells diverge to several different effector classes, identified by their ability to express different set of genes. Aside from the genes encoding components of the TCR/CD3, there are many others that are activated and/or inactivated during T-cell development, but the functions of most of them are not yet defined. Despite the significant progress made, several fundamental aspects of the major steps of T-cell differentiation remains unclear. Thus, while long ago it was realized that the thymus is a central organ for the development of functionally competent T lymphocytes, it appears clear today that ectopic T-cell differentiation can also take place. In this article we review some of the molecules implicated in T-cell development and discuss some of the pathways that lead to mature T cells from precursors, both intra- and extra-thymically, as well as their implications in the acquisition of self tolerance.

Cell Differentiation↗
PubMedDate not supplied

[Endoscopic management of biliary fistula].

From January 1991 to July 1993 we diagnosed 16 patients with biliary fistulas. Nine patients showed a fistula of the stump after cholecystectomy (two laparoscopic and the rest in a conventional form). In none was there any evidence of residual stones. Three patients that showed biliary fistula who had residual stones which was no diagnosed during surgery. Four patients had biliary fistulas at different levels after abdominal traumas due to bullet wounds. All the patients were treated endoscopically by means of endoscopic sphincterotomy and in one of them it was necessary to place a biliary stent due to the fact that there was a stricture under the level of the fistula. One patient who, in addition to the fistula had an abscess was drained guided by ultrasound after the sphincterotomy. The evolution of the patients was satisfactory. There were no complications because of the procedure.

Adolescent↗
PubMedDate not supplied

[Colitis due to radiation: endoscopic management with heat probe].

Rectal bleeding is a frequent symptom in radiation colitis, and is due to vascular lesions usually confined to the rectum. We present our preliminary experience with the use of the heater probe, in eight patients with radiation proctitis, whose main symptom was rectal bleeding. Six patients had radiation for carcinoma of the cervix and 2 had endometrial cancer. One to four sessions of coagulation were performed with an intensity of 200 to 400 Joules per session. In all patients a good response was obtained, bleeding diminished or stopped completely, with improvement of blood counts and the need for transfusions. We think that heater probe is a good therapeutic alternative, for the management of these difficult complication.

Cautery↗