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R Escalante

Publications and source records attributed to R Escalante.

30 records · Page 2Linked to original sources
PubMed1994

Identification of an Artemia franciscana retropseudogene containing part of the last exons of the sarco/endoplasmic reticulum Ca-ATPase-encoding SERCA gene.

A genomic clone has been isolated which contains sequences highly homologous to part of exon 14 and exons 15, 16 and 17 of the Artemia franciscana sarco-endoplasmic reticulum Ca-ATPase(SERCA)-encoding gene, but none of the introns. The homologous region extends to the 3' end of the mRNA, although the poly(A) tail is not present. The structure of this clone suggests that it represents a 5'-end-truncated retropseudogene (r psi).

Animals↗
PubMed1994

Structure of Artemia franciscana sarco/endoplasmic reticulum Ca-ATPase gene.

Genomic clones coding for the Artemia franciscana sarco(endo)plasmic reticulum Ca-ATPase have been isolated. The restriction map of the overlapping clones covers a region of 65 kilobases of DNA. Nucleotide sequence of mRNA coding regions shows that the gene is divided into 18 exons separated by 17 introns. Compared with the structure of the rabbit sarco(endo)plasmic reticulum Ca-ATPase 1 gene, 12 of the introns are in the same position, 8 introns present in the rabbit gene are absent from A. franciscana, 4 introns present in A. franciscana are not found in rabbit, and the position of 1 intron is shifted one base between both genes. Southern blot analysis strongly suggests that this is the only sarco(endo)plasmic reticulum Ca-ATPase gene present in A. franciscana. Primer extension and nuclease S1 protection experiments have shown the existence of two main regions of transcription initiation separated by 30 nucleotides. Transcription is initiated in both regions at two or three consecutive bases. A hexanucleotide that includes the initiation sites is repeated in both transcription initiation regions. The nucleotide sequence of the promoter region shows the existence of several putative regulatory sites, including some that are muscle-specific such as one CArG box, 3 MEF-2, and 8 putative binding sites for muscle transcription factors of the MyoD family.

Amino Acid Sequence↗
PubMed1993

Similar alternative splicing events generate two sarcoplasmic or endoplasmic reticulum Ca-ATPase isoforms in the crustacean Artemia franciscana and in vertebrates.

A second isoform of the Artemia franciscana sarcoplasmic or endoplasmic reticulum Ca-ATPase has been identified through the isolation of cDNA clones. This isoform differs from the previously identified one only at the C-terminal end of the protein. The last 6 amino acids of the former isoform change to 30 hydrophobic amino acids in the newly identified isoform that have the potentiality of being an additional transmembrane domain. The two A. franciscana isoforms are highly homologous to the two isoforms coded by the mammalian and bird SERCA2 gene, except that the C-terminal extensions share their hydrophobic character but have no significant amino acid homology. The isolation of genomic clones coding for this region of the gene shows that both isoforms arise from the same gene by alternative splicing. The donor splicing site of the penultimate exon can either be recognized and fused to the last exon, giving rise to the mRNA coding for the shortest protein, or remain unrecognized, in which case a polyadenylation site is recognized before the last exon of the gene and the mRNA coding for the largest protein is originated. The alternative splicing used to originate the two isoforms is similar in Artemia and vertebrates. The conservation of the alternative splicing between species so distant in evolution suggests an important physiological role for the existence of the two isoforms of the protein.

Alternative Splicing↗
PubMed1993

Transferrin gene expression in the mammary gland of the rat. The enhancing effect of 17 beta-oestradiol on the level of RNA is tissue-specific.

We have investigated the physiological factors which regulate transferrin gene expression in the mammary gland of the rat. Our studies by dot blot analysis have demonstrated that multiple doses of 17 beta-oestradiol (OE2; 0.5 mg/kg per day for 3 days) elicit a specific 3.5-fold increase in the transferrin mRNA levels in the mammary glands of virgin rats. The hormonal action of OE2 in mammary tissue was specific for the transferrin gene, as judged by hybridization with beta-actin cDNA. The accumulation of transferrin mRNA induced by OE2 treatment was similar to the developmentally regulated expression of the gene observed during the reproductive cycle. The steady-state level of mammary transferrin mRNA increased by up to 4.5-fold at day 21 of lactation, when compared with virgin and pregnant rats. Our results show that the pattern of transferrin gene expression is different in mouse and rat mammary glands. The specific response of the transferrin gene to OE2 was not found in the liver or in the uterus. In the uterus alone, OE2 produced a significant increase in the content of nucleic acids and also induced the accumulation of transferrin and beta-actin mRNAs. We have detected for the first time an induction of transferrin gene expression in the mammary gland in response to OE2, and these results support the view that the pattern of transferrin gene multi-modulated expression is tissue- and species-specific.

Animals↗
PubMed1992

The effect of upright tilt on nifedipine-induced natriuresis.

Calcium channel blockers are antihypertensive agents with diuretic actions. Yet edema occurs in some patients receiving long-term treatment with these drugs. As with other vasodilators, stimulation for fluid retention could result from systemic vasodilation. We speculated that the upright posture could enhance sodium retention. To test this hypothesis, we studied the effect of upright tilt in 10 patients before and after the oral administration of 20 mg nifedipine. Before nifedipine upright tilt caused a 41% drop in the sodium excretion rate, from 0.27 +/- 0.04 to 0.16 +/- 0.03 meq/min (p less than 0.05). Fractional sodium excretion decreased by 46%, from 2.4 +/- 0.5 to 1.3 +/- 0.3% (p less than 0.01). Urinary volume and renal plasma flow also decreased (p less than 0.05). Plasma renin activity (PRA) rose by 46% (p less than 0.005). With the patients in the supine posture nifedipine increased the sodium excretion rate to 0.49 +/- 0.09 meq/min (p less than 0.05). Fractional sodium excretion was 3.1 +/- 0.6 meq/min (p = 0.2). The natriuresis took place despite a fall in mean blood pressure and a significant rise in PRA (up 115% from prenifedipine supine values, p less than 0.005). Renal plasma flow also increased (p less than 0.01). The upright tilt caused a reversal of the nifedipine-induced natriuresis. The sodium excretion rate dropped to 0.23 +/- 0.05 meq/min and fractional sodium excretion to 1.3 +/- 0.2% (both not different from control). This drop in natriuresis occurred while mean blood pressure was at its lowest and PRA was 254% above the initial levels (p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Gene expression after resumption of development of Artemia franciscana cryptobiotic embryos.

The steady-state levels of six different mRNAs have been studied during Artemia franciscana development. Some of these mRNAs are present in the cryptobiotic cyst, like those coding for cytoplasmic actins, sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase, and the Na+, K(+)-ATPase alpha-subunit isoform coded by the clone pArATNa136. The expression of these mRNAs is markedly induced during cyst development. A small increase in mRNA levels can be observed for some genes at very early stages of development (2 h). The main increase is observed between 4 and 16 h of development for all these genes, although the time course of mRNA accumulation is different for each one of the genes studied. Some other genes, like those coding for muscle actin (actin 3) or the Na+, K(+)-ATPase alpha-subunit isoform coded by the cDNA clone alpha 2850, are not expressed in the cyst before resumption of development and their expression is induced after 10 or 6 h of development, respectively. These data on the kinetic of mRNA accumulation provide the information required to determine transcriptionally active developmental stages, necessary to study in more detail the mechanisms of transcriptional regulation during activation of cryptobiotic cysts and resumption of embryonic development.

Actins↗
PubMedDate not supplied

[Prolonged total parenteral nutrition in surgery. A case report of severe malnutrition].

We present a 15-years-old female patient severely malnourished due to complications of abdominal surgery, who received total parenteral nutrition during 118 days. The clinical and laboratory parameters are analyzed and a photographic sequence is presented. During the treatment period nitrogen balance was positive and her weight increased in 50%.

Acute Disease↗
PubMedDate not supplied

[Fulminant amebic colitis and ameboma in the same patient].

Fulminant amebic colitis is an infrequent complication of amebiasis with a high mortality rate. The presence of a tumoral mass caused by ameba (ameboma) in the rectum or the colon is also of rare occurrence and can cause diagnostic difficulties. We report the case of a pregnant 27 year old patient with the association of both pathologies.

Adult↗
PubMedDate not supplied

[A community referral system for the permanent program of universal vaccination].

This article describes a community referral system for the permanent immunization program, tested in Tijuana, Baja California, Mexico, by the Regional Nucleus for Health Systems Development (NUREDESS-Norte). The model was designed to facilitate the participation of the intermediate organizations that make up the community in urban settings. Through appropriate technology, health counselors identify with precision, ease and rapidity the specific immunization needs of pre-school age children. The counselors also help diminish the barriers in the way to service access, and follow-up the children at highest risk.

Child↗
PubMedDate not supplied

[Total and segmental colonic transit time. Clinical and prospective study using radiopaque markers in normal subjects].

We studied 18 normal voluntary subjects who received a diet containing 20 to 35 grams of fiber. A capsule with 20 radiopaque markers was given with breakfast and plain abdominal films of the abdomen taken every 12 hours until complete elimination of the markers. Calculation performed according to Ahran formula and final values were the result of the mean of all the subjects studied. Colonic transit time was 27.6 hours, right colon transit time: 7.2 hs; left colon transit time: 9.6 hs. and rectosigmoid transit time: 10.8 hs.

Adult↗
PubMedDate not supplied

[Leiomyosarcoma of the gastrointestinal tract].

The records and biopsies of 10 patients with the diagnosis of leiomyosarcomas admitted at the Military Hospital "Dr. Carlos Arvelo" from 1962 to 1991, were reviewed. The sample correspond to 0.47% of all gastro-intestinal tumors. Sixty per cent of tumors were localized in the stomach, 20% in the jejunum, 10% in the duodenum and 10% in the colon. Eighty per cent had pain and 60% had bleeding. Sixty per cent of tumors were low grade leiomyosarcomas and 40% were epithelioid leiomyosarcomas. In eight of nine patients operated, resection was done. The survival range was from six months to 28 years with a median of 12 years. The most important prognostic factor was the extension of the tumor, independently of he histologic type.

Adult↗