Biomedical subjects

R Casillas

Publications and source records attributed to R Casillas.

7 recordsLinked to original sources

PubMed2005

Multi-day radon signals with a radioactive decay limb -- occurrence and geophysical significance.

Multi-day signals, generally with duration of 2-10 days, are a prominent temporal variation type of radon (Rn) in geogas in the unsaturated zone. Rare multi-day Rn signals have been found which are characterized by: (a) a declining limb lasting up to 10 days which conforms to the radioactive decay of Rn, (b) recurs at the same location and (c) is recorded in diverse situations-volcanic and seismogenic. It suggested that a Rn blob is injected at a lower level on a steady upward flow of geogas whereby the rise and final fall of the signal are attributed to the edges of the blob while the central Rn-decay segment records the passing of the decaying blob itself. Rn-decay signals are a small subset of multi-day Rn signals which are considered as highly irregular and unusable for the understanding of geophysical processes. In difference, it is concluded that multi-day Rn signals are probably proxies of subtle geodynamic processes at upper crustal levels and are therefore significant for studying such processes.

Journal Article↗

PubMed2001

VIP gene transcription is regulated by far upstream enhancer and repressor elements.

SK-N-SH human neuroblastoma subclones differ widely in basal and second messenger induction of the gene encoding the neuropeptide vasoactive intestinal peptide (VIP). These differences were recapitulated by a chimeric gene which consisted of 5.2 kb of the human VIP gene 5' flanking sequence fused to a reporter. Subsequent gene deletion experiments revealed several regulatory regions on the gene, including a 645-bp sequence located approximately 4.0 upstream from the transcription start site. Here we examined this upstream region in detail. Inhibitory sequences were found to be present on each end of the 645-bp fragment. When removed, basal transcription increased more than 50-fold. Subsequent deletion/mutation analysis showed that the 213-bp fragment contained at least two enhancer elements. One of these was localized to an AT-rich 42-bp sequence shown by others to bind Oct proteins in neuroblastoma cells, while the other corresponded to a composite AP-1/ets element. In addition to these enhancers, a 28-bp sequence on the 213-bp fragment with no apparent homology to known silencers inhibited transcription. The studies provide molecular details of a complex regulatory region on the VIP gene that is likely to be used to finely tune the level of gene transcription in vivo.

5' Untranslated Regions↗

PubMed1999

Targeting of embryonic and postnatal autonomic and enteric neurons with a vasoactive intestinal peptide transgene.

The neuropeptide vasoactive intestinal peptide (VIP) is expressed in several distinct sites in the CNS, in cholinergic and enteric ganglia, and in a small subpopulation of neurons within sympathetic ganglia. Previous studies on the human VIP gene indicate that transcription in neural crest-derived neuroblastoma and pheochromocytoma cell lines is controlled in part by multiple regulatory elements located along 4.5 kb of upstream 5' flanking sequence. In the current studies, transgenic mice were created with a chimeric gene consisting of 16.5 kb of the mouse VIP gene fused to the beta-galactosidase reporter. In situ hybridization analysis in adult mice indicated that reporter gene expression was correctly targeted to neurons in the esophagus, stomach, small intestine, and colon. No expression was observed in the brain, including regions that contain abundant VIP-expressing cells, such as the thalamus, amygdala, cerebral cortex, hippocampus, and suprachiasmatic nucleus. Analysis of transgene expression in neonatal and embryonic day 13.5 mice revealed a near perfect correlation between VIP and beta-galactosidase gene expression in cranial cholinergic ganglia and the superior cervical ganglia, and lack of transgene expression in sensory ganglia and in nonneuronal tissue. Potential ectopic transgene expression was observed in neonates, in the cerebellar external granule layer and in a small subpopulation of neurons in the olfactory epithelium. We conclude that the 16.5 kb of VIP gene used in these studies contains sequences sufficient for directing expression specifically to VIP neurons in the PNS, and that sequences located elsewhere on the gene are required for proper CNS expression. The VIP gene sequences used here should be capable of targeting other gene products to specific populations of embryonic and adult peripheral neurons without causing significant expression in the CNS.

Aging↗

PubMed1997

Histopathologic features seen with different animal models following cutaneous sulfur mustard exposure.

In an effort to understand the pathophysiology of sulfur mustard (2,2' dichlorodiethyl sulfide, HD)-induced cutaneous lesions, a number of animal models have been used. Animal models have been and will continue to be used in the development of therapeutic strategies to protect against and/or moderate lesions, and to potentiate wound healing after HD exposure. Upon reviewing the histopathologic features seen after HD-exposure, we propose roles for different animal models in HD-research. Hematoxylin and eosin slides from protocols done originally as dose response studies for either liquid or vapor HD-exposures were examined. The animal models reported include the hairless guinea pig (HGP), weanling pig (WP), mouse ear (ME) and hairless mouse (HM). In all these animal models. HD induces subepidermal blister formation as well as epidermal cell death. The HGP appears to be the most sensitive model for epidermal necrosis. The HGP and, to a lesser degree, the HM react with a marked neutrophilic infiltrate. The ME provides a quantitative measure for HD effects and a mild inflammatory infiltrate similar to what is seen in human skin. Doses necessary to produce microblister formation in the WP are usually associated with more significant stromal and vascular changes than in other animal models. In addition to a quantitative measure of the HD effect and a mild inflammatory response, the cost, as well as the availability of specific antibodies, and DNA and RNA probes and primers gives the ME advantages for both drug screening and for the study of the pathophysiology of HD-induced cutaneous lesions. The sensitivity of the HGP and the abundant experience with vapor exposures establishes a place for this animal model in barrier cream and drug screening. The similarity of WP skin to human skin is important in the study of wound healing after HD exposure, as well as in the study of the pathophysiology of the cutaneous lesion and in more definitive therapeutic studies.

Animals↗

PubMed1991

Skin testing compared with in vitro testing for screening allergic patients.

A new FDA-cleared product has been introduced for screening suspected allergic patients using a small blood sample. The QUIDEL Allergen Screens (AS) are simple to use dipstick tests that measure allergen-specific IgE to ten of the most important regional allergens. We compared the results obtained by prick-puncture skin testing (ST) to those obtained with the AS on 103 patients with allergic symptoms. Of the 103 patients studied, there were 67 with positive skin tests, and 57 of those were positive by AS and ten were AS negative. Of the 36 with negative skin tests, 2 were positive by AS and 34 were AS negative. Compared with ST, the AS results gave a sensitivity of 85% and a specificity of 94% for identifying the allergic patient. Of the ten patients positive by ST but negative by AS, five were ST positive at the 1+ level; the other five were repeatedly negative by AS and confirmed negative by RAST. On an allergen basis, the ST and AS methods showed an 85% agreement. A subset of 24 patients from the foregoing group was studied for total IgE and allergen-specific IgE with products from both Pharmacia (P) and QUIDEL (Q). In this group of patients, skin test results gave seven patients negative and 18 patients positive to one or more allergens. While the overall Total IgE results were higher for ST patients, the Total IgE results alone did not effectively discriminate between ST-positive and ST-negative patients. The allergen-specific, however, results by both methods showed excellent agreement with the ST results.(ABSTRACT TRUNCATED AT 250 WORDS)

Allergens↗

PubMed1987

Long-term studies in prevention of food allergy: patterns of IgG anti-cow's milk antibody responses.

Over the past 7 years we have enrolled several hundred families in a study of the prophylaxis of atopic allergy. Initially, control and study patients were at different institutions, but more recently a true double-blind random assignment to control or study group has been instituted. Nevertheless, all of the infants from these highly atopic families can be utilized to obtain the data reported; that is, the rate of change of IgE levels, the appearance of food sensitization (food-specific IgE), the signs and symptoms of atopic allergy diseases and the changes in cow's milk-specific IgG antibody during the first 2 years of life. Some aspects of the first three of these parameters have been presented in the eight references to this paper, but only preliminary data on the use of IgG anti-cow's milk antibody as a measure of compliance has been available. In this paper an analysis is presented of the various patterns of IgG antibody levels in the first 60 infants of the over 200 who have been studied to date. Both the age of onset and the subsequent changes in the foregoing immunologic measurements provide fundamental data with which to measure the success rate of any prophylactic or therapeutic regimen and may improve our capacity to predict the future course of infants and children with a strong familial tendency to allergy.

Animals↗

PubMedDate not supplied

[Characteristics of Guatemalan migration of the Soconusco region in the State of Chiapas].

This paper describes and analyzes the main characteristics identified in seasonal Guatemalan workers who migrate every year to coffee plantations in the Sosonusco region in the state of Chiapas. Stress is placed on the disadvantageous working and living conditions of said population in their original areas of residence, as a necessary referent for understanding the nature and function of seasonal migratory work as a part of a social sector whose living conditions are marked by poverty. The data utilized for the analysis were obtained through a survey carried out in the 1986-1987 harvest season, in which 591 migrants working in 13 ejido or privately-owned productive units in the municipalities of Tapachula and Union Juarez were interviewed.

Americas↗