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Biomedical subjects

E Martinez

Publications and source records attributed to E Martinez.

At least 55 records · Page 3Linked to original sources
PubMed2001

The observation unit: a new interface between inpatient and outpatient care.

PURPOSE: Observation units for patients who present to emergency departments with chest pain have become common. We describe our 3-year experience with a multipurpose observation unit in which chest pain accounts for only a minority of patients' presenting clinical syndromes. SUBJECTS AND METHODS: We analyzed the effects of a 12-bed observation unit on inpatient admissions for common clinical syndromes, as well as its overall effects on inpatient medical admissions during its first 3 years of operation (1996 to 1998) compared with the 3 years preceding its creation (1993 to 1995). RESULTS: Among 7,507 patients admitted to the observation unit in 1996 to 1998, 6,334 (85%) were discharged home within 23 hours. Total inpatient medical admissions fell by a similar number (n = 5,366) during the 3 years of operation of the observation unit when compared with the 3 preceding years (39,569 admissions in 1996 to1998 versus 44,935 in 1993 to 1995). Analysis of local area trends suggested that the use of the observation unit contributed to reduced hospital admissions, rather than vice versa. CONCLUSION: Observation units can serve patients with diverse clinical syndromes and may reduce inpatient admissions. This novel "point of care" deserves further evaluation.

Ambulatory Care↗
PubMed2001

A reproducible approach to the reporting of organochlorine compounds in epidemiologic studies.

A growing body of research indicates that the most biologically active PCB congeners and organochlorines are not the most abundant components in human and wildlife samples. As researchers attempt measurement on a wider pool of less abundant compounds, they inevitably face quantification problems. To address this problem and enhance comparability across studies, we propose a standardized approach to report organochlorines that is based on a reproducible method to determine the limit of quantification (LQ). Two statistical methods are incorporated into our approach, one by Gibbons termed the Alternative Minimum Level (AML), and one based on determining a region of stable relativestandard deviation in instrument response (RSD). We illustrate our approach using historical samples collected during the 1960s from a cohort of pregnant women enrolled in the Child Health and Development Study. The results are applicable to determining the LQ of any method, and are of utmost importance to environmental scientists conducting trace organic analyses of complex mixtures. Our results demonstrate that: (1) precision as measured by RSD is the most important criterion in determining LQ; (2) the AML routinely isolates a region of constant RSD; and (3) the precision of the instrument detector response as measured with pure standards locates the LQ applicable for real samples - that is, the true limits of quantification reside in the detector, not the matrix effects or analyte recoveries associated with real samples. A corollary of these findings is that bias due to matrix effects and analyte recoveries can be assessed separately from precision and LQdetermination. Previous approaches involved spiking matrix blanks to determine LQ, a problematic strategy for real world, complex matrices. We have now validated the use of pure standards in LQ determination, an approach that is practical and accessible to most analysts.

Animals↗
PubMed2001

Influence of thickness on the properties of hydroxyapatite coatings deposited by KrF laser ablation.

The growth of hydroxyapatite coatings obtained by KrF excimer laser ablation and their adhesion to a titanium alloy substrate were studied by producing coatings with thicknesses ranging from 170 nm up to 1.5 microm, as a result of different deposition times. The morphology of the coatings consists of grain-like particles and also droplets. During growth the grain-like particles grow in size, partially masking the droplets, and a columnar structure is developed. The thinnest film is mainly composed of amorphous calcium phosphate. The coating 350nm thick already contains hydroxyapatite, whereas thicker coatings present some alpha tricalcium phosphate in addition to hydroxyapatite. The resulting coating to substrate adhesion was evaluated through the scratch test technique. Coatings fail under the scratch test by spallating laterally from the diamond tip and the failure load increases as thickness decreases, until not adhesive but cohesive failure for the thinnest coating is observed.

Alloys↗
PubMed2001

Southern Mexican minnows of the genus Notropis (Actinopterygii, Cyprinidae): genetic variation, phylogenetic relationships and biogeographical implications.

Allozyme analyses were performed to determine patterns of genetic variation and phylogenetic relationships within the genus Notropis in southern Mexico. Products of 28 gene loci were resolved in 24 geographic samples belonging to four putative species. These species represent the southern limit of the Cyprinidae in North America. Five loci were found monomorphic and 11 were diagnostic among species when the outgroup, Phoxinus phoxinus, was not taken into account. Four groups were identified, but these do not correspond perfectly to the four nominal species. Notropis sallaei was identified by allozyme analyses being the most basal among southern Mexican Notropis and the most genetically divergent. Notropis imeldae, was also diagnosed on the basis of allozymic variation, however a population sample representing the Balsas drainage was genetically divergent and is considered as an undescribed new species (N. n. sp.). No genetic differences were found between the samples of N. boucardi and N. moralesi. Therefore, we recommend that N. moralesi should be considered as a junior synonym of N. boucardi. A broad geographic sampling strategy was employed across all the distribution range of N. boucardi representing rivers from three different drainages, which cover both Mexican slopes. The slight divergence found among the headwater populations of N. boucardi permitted us to predict a model of paleohydrographic relationships of these three drainages. Two alternative hypotheses are postulated to explain the current distribution pattern of populations of N. boucardi in southern Mexico.

Journal Article↗
PubMed2001

Maternal consumption of pulque, a traditional central Mexican alcoholic beverage: relationships to infant growth and development.

OBJECTIVES: To document the consumption during pregnancy of pulque, a traditional central Mexican alcoholic beverage, and its relationship to subsequent infant size, physical growth and performance on the Bayley Scales of Infant Development. DESIGN: Prospective cohort study. SETTING: Six villages in rural, central Mexico in 1984-1985. SUBJECTS: Seventy mother-infant pairs. RESULTS: Most women (72.9%) consumed pulque during pregnancy, and 28.6% consumed more than 150 g ethanol week(-1) from the beverage. Individuals who consumed pulque showed no compensating decrease in energy obtained from other foods. Pulque consumption possessed curvilinear relationships with both infant length (at 1 and 6 months) and Bayley mental performance (at 6 months). Heavy pulque intakes were associated with smaller infant size and poorer mental performance. In modest quantities, pulque consumption may have been beneficial due to its micronutrient content. CONCLUSIONS: Intakes of alcohol from pulque were common among pregnant women in these rural, central Mexican villages. Given current scientific knowledge of the adverse effects of ethanol on foetal development, public health interventions are needed to reduce heavy pulque consumption during pregnancy in some areas of rural Mexico.

Adult↗
PubMed2001

The evolving mode of presentation of HIV-infected patients to health services of northern Spain: 1985 through December 1999.

To evaluate the mode in which human immunodeficiency virus (HIV)-infected patients have had their first contact with the health services throughout time as well as their demographic and immunologic features, all 1,076 adult HIV-infected patients seen at our institution were grouped by the year of presentation. The patients' age and gender, the mode of presentation (admitted through the emergency department or seen at the outpatient clinic), and the presence of acquired immune deficiency syndrome (AIDS)-defining conditions and CD4 counts at the time of presentation were analyzed. The patients' age at presentation and the rate of female patients increased throughout time (p < 0.001, and p = 0.01, respectively). There was a progressive decline in the proportion of patients who were hospitalized until the mid-1990s (p < 0.0001), followed by a rise during the subsequent years (p = 0.04). This U-shaped curve was opposite to that of CD4 counts, which was ascending until 1994 (p = 0.04), to decline progressively later (p = 0.1). Patients whose first contact with the hospital was through admission had lower CD4 counts (p = 0.007), and higher rates of AIDS diagnosis throughout time (p < 0.0001). We conclude that some features of HIV-infected patients at the time of their first contact with the health services are changing over time, such as older age, increasing numbers of women, and higher degrees of immunosuppression. These findings seem to reflect the increasing number of patients unaware of their past risk factors, and should be considered for the development of strategies targeted to this population in order to allow earlier detection of their infection.

Adolescent↗
PubMed2001

Human STAGA complex is a chromatin-acetylating transcription coactivator that interacts with pre-mRNA splicing and DNA damage-binding factors in vivo.

GCN5 is a histone acetyltransferase (HAT) originally identified in Saccharomyces cerevisiae and required for transcription of specific genes within chromatin as part of the SAGA (SPT-ADA-GCN5 acetylase) coactivator complex. Mammalian cells have two distinct GCN5 homologs (PCAF and GCN5L) that have been found in three different SAGA-like complexes (PCAF complex, TFTC [TATA-binding-protein-free TAF(II)-containing complex], and STAGA [SPT3-TAF(II)31-GCN5L acetylase]). The composition and roles of these mammalian HAT complexes are still poorly characterized. Here, we present the purification and characterization of the human STAGA complex. We show that STAGA contains homologs of most yeast SAGA components, including two novel human proteins with histone-like folds and sequence relationships to yeast SPT7 and ADA1. Furthermore, we demonstrate that STAGA has acetyl coenzyme A-dependent transcriptional coactivator functions from a chromatin-assembled template in vitro and associates in HeLa cells with spliceosome-associated protein 130 (SAP130) and DDB1, two structurally related proteins. SAP130 is a component of the splicing factor SF3b that associates with U2 snRNP and is recruited to prespliceosomal complexes. DDB1 (p127) is a UV-damaged-DNA-binding protein that is involved, as part of a complex with DDB2 (p48), in nucleotide excision repair and the hereditary disease xeroderma pigmentosum. Our results thus suggest cellular roles of STAGA in chromatin modification, transcription, and transcription-coupled processes through direct physical interactions with sequence-specific transcription activators and with components of the splicing and DNA repair machineries.

Acetylation↗
PubMed2001

The type 2 iodothyronine deiodinase is expressed in the rat uterus and induced during pregnancy.

Thyroid hormones are of considerable importance for vertebrate reproductive function and during development. To further assess the role of these compounds in this capacity, we examined the expression pattern of the type 2 iodothyronine deiodinase (D2), which converts T(4) to the more active hormone T(3), in the rat uterus in both the nonpregnant and the pregnant state. D2 activity was identified as the predominant, if not only, 5'-deiodinase in the nonpregnant rat uterus. The expression of D2 messenger RNA was located by in situ hybridization to the endometrial stromal cells, where the signal was particularly enriched in the region adjacent to the epithelial cells of the uterine lumen. During pregnancy, D2 activity increased, peaking on day 17 of gestation (embryonic day 17). At that time, uterine D2 activity exceeded that in the placenta, as well as that in the fetal tissues. In the earlier stages of pregnancy before placental formation (e.g. embryonic days 10-11), D2 messenger RNA in the rat uterus was located outside the decidual tissue, which was observed, as in previous studies, to highly express the inactivating type 3 deiodinase. In summary, the rat uterus, particularly during pregnancy, seems to be a site of active thyroid hormone metabolism, presumably designed to maintain the optimal thyroid hormone environment for both the fetus and the maternal uterine tissue.

Animals↗
PubMed2001

Domestic and peridomestic transmission of American cutaneous leishmaniasis: changing epidemiological patterns present new control opportunities.

Predictions that deforestation would reduce American cutaneous leishmaniasis incidence have proved incorrect. Presentations at a recent international workshop, instead, demonstrated frequent domestication of transmission throughout Latin America. While posing new threats, this process also increases the effectiveness of vector control in and around houses. New approaches for sand fly control and effective targeting of resources are reviewed.

Animals↗
PubMed2000

Effects of antiandrogens on chromatin remodeling and transcription of the integrated mouse mammary tumor virus promoter.

Inhibition of the ligand-activated androgen receptor (AR) by antiandrogens plays an important role in the treatment of various hyperandrogenic disorders including prostate cancer. However, the molecular mechanisms of antiandrogen activity in vivo remain unclear. In this study we analyzed the effects of cyproterone acetate (CPA), flutamide (F), and hydroxyflutamide (OHF) on transcriptional activation and chromatin remodeling of the genomically integrated mouse mammary tumor virus (MMTV) promoter. This promoter has provided an excellent model system to study the impact of steroid hormones on transcriptional activation in the context of a defined chromatin structure. The MMTV hormone response element is positioned on a phased nucleosome, which becomes remodeled in response to steroids. We utilized this model system in mouse L-cell fibroblasts that contain a stably integrated MMTV promoter. In these cells, dihydrotestosterone (DHT) induced a large increase of AR protein levels that correlated with transcriptional activation and chromatin remodeling of the MMTV promoter. Coadministration of DHT and CPA or DHT and OHF in these cells inhibited the increase of AR levels, which resulted in a strong blockage of transcriptional activation and chromatin remodeling of the MMTV promoter. In contrast, F had no significant influence on these activities. We conclude that a major portion of the antiandrogenic effects of CPA and OHF in vivo are mediated by the reduction of AR levels.

Androgen Antagonists↗
PubMed2000

Alterations in relaxation to lactate and H(2)O(2) in human placental vessels from gestational diabetic pregnancies.

We determined whether alterations in the mechanism of relaxation to H(2)O(2) potentially contribute to the enhanced prostaglandin-mediated contractile response to H(2)O(2) and posthypoxic reoxygenation seen in human placental vessels of pregnancies with gestational diabetes mellitus (GDM). Isolated placental arteries and veins from GDM and uncomplicated full-term pregnancies were precontracted with prostaglandin F(2alpha) (PO(2) 35-38 Torr) and then exposed to lactate (1-10 mM), arachidonic acid (0.01-10 microM), nitroglycerin (1 nM-1 microM), forskolin (0.01-10 microM), or H(2)O(2) (1 microM-1 mM + 10 microM indomethacin). The rates of tissue H(2)O(2) metabolism by catalase and nitrite production were measured. The relaxation to lactate was reduced in GDM placental arteries and veins by 54-85 and 66-80%, and the relaxation to H(2)O(2) was inhibited by 80-94% in GDM placental veins compared with vessels from uncomplicated full-term pregnancies. H(2)O(2) caused only minimal relaxation of placental arteries. Responses to other relaxing agents were not altered in the GDM placental vessels. Diabetic vessels showed rates of nitrite production that were increased by 113-195% and rates of H(2)O(2) metabolism by catalase that were decreased by 44-61%. The loss of relaxation to H(2)O(2) and lactate (mediated via H(2)O(2)), perhaps as a result of the inhibition of catalase by nitric oxide, may explain the previously reported enhancement of prostaglandin-mediated contractile responses to H(2)O(2) and posthypoxic reoxygenation seen in GDM placental vessels.

Adolescent↗
PubMed1999

Human TATA-binding protein-related factor-2 (hTRF2) stably associates with hTFIIA in HeLa cells.

The TATA-binding protein (TBP)-related factor TRF1, has been described in Drosophila and a related protein, TRF2, has been found in a variety of higher eukaryotes. We report that human (h)TRF2 is encoded by two mRNAs with common protein coding but distinct 5' nontranslated regions. One mRNA is expressed ubiquitously (hTRF2-mRNA1), whereas the other (hTRF2-mRNA2) shows a restricted expression pattern and is extremely abundant in testis. In addition, we show that hTRF2 forms a stable stoichiometric complex with hTFIIA, but not with TAFs, in HeLa cells stably transfected with flag-tagged hTRF2. Neither recombinant human (rh)TRF2 nor the native flag.hTRF2-TFIIA complex is able to replace TBP or TFIID in basal or activated transcription from various RNA polymerase II promoters. Instead, rhTRF2, but not the flag.hTRF2-TFIIA complex, moderately inhibits basal or activated transcription in the presence of rhTBP or flag.TFIID. This effect is either completely (TBP-mediated transcription) or partially (TFIID-mediated transcription) counteracted by addition of free TFIIA. Neither rhTRF2 nor flag. hTRF2-TFIIA has any effect on the repression of TFIID-mediated transcription by negative cofactor-2 (NC2) and neither substitutes for TBP in RNA polymerase III-mediated transcription.

Amino Acid Sequence↗
PubMed1999

Comparative study of carbohydrate antigen 195 and carcinoembryonic antigen for the diagnosis of pancreatic carcinoma.

The expression CA195 in serum, defined by monoclonal antibody CC3C195 (IgM), was studied in 67 patients with pancreatic cancer and in 138 patients with biliary or pancreatic benign disease. The results were compared with carcinoembryonic antigen (CEA) expression. The overall sensitivity of the CA195 assay (> 12 U/ml) was higher than that for CEA (89.5% vs. 53.7%) (p < 0.001). Sensitivity was increased to 92.5% with the simultaneous use of the two antigens, but the difference was statistically significant only with CEA (p < 0.001). The specificity of CA195 calculated from all patients with benign diseases was lower than that of CEA (73.1% vs. 89.8%). However, using a cutoff value of 100 U/ml for CA195, the specificity of this antigen (82%) was higher than that of CEA. These results demonstrate that marked elevations of tumor antigen CA195 are relatively specific for pancreatic carcinoma, and that this antigen is superior to CEA for diagnosing pancreatic cancer by virtue of its higher sensitivity.

Antibodies, Monoclonal↗
PubMed1999

Renal artery stenosis treated with stent deployment: indications, technique, and outcome for 108 patients.

From January 1993 to May 1996, 108 patients (64 men, 44 women; mean age, 72 years; age range, 37 to 87 years) underwent 125 percutaneous transluminal angioplasties and stent implantations primarily for atherosclerotic lesions of the renal artery. Sixty-four patients underwent treatment for renovascular hypertension (two antihypertensive medications or more), 32 patients underwent treatment for a combination of hypertension and renal failure (serum creatinine level >/=1.6 mg/dL), and a small group of six patients (5%) without hypertension or diminished renal function underwent treatment to prevent the progression to renal artery occlusion and kidney loss. Thirty-three patients (31%) had renovascular hypertension that was classified as severe on three or more medications, 31 patients (29%) had renovascular hypertension that was classified as moderate on two medications, and 38 patients (35%) had renovascular hypertension that was classified in the mild group on a single antihypertensive agent. Stenotic lesions were located at the ostium of the renal artery in 82 cases (65%) and were ostial-adjacent (<5 mm from renal ostium) in the other 43 cases (34%). A total of 125 stents were deployed in 125 arteries (procedural success 97.6%). Renovascular hypertension either was cured or was improved in 73 patients (68%), with 14 patients (13%) considered cured (normotensive on no medications). The conditions of 29 patients (27%) were unchanged, and 6 patients (5%) had worsening hypertension after surgery. We were unable to demonstrate a statistically significant improvement in serum creatinine levels after renal artery balloon angioplasty/stenting. Complications occurred in a total of nine cases (7.2%), six of which were related to technical problems. One patient had worsening renal insufficiency caused by contrast agent, and another patient had a perinephric hematoma develop that necessitated evacuation. There were four postoperative deaths (30-day mortality). Two of these deaths were caused by postoperative myocardial infarction. The other two patients had progressive renal failure develop that necessitated dialysis. These patients later died of the disease process despite supportive care. Follow-up renal artery duplex scan studies and angiograms were available on 96 patients (76%). The mean peak systolic renal/aortic ratio on duplex scanning was 2.2. Life-table analysis yielded a 74% primary patency rate and an 85% secondary patency rate at 36 months. This retrospective analysis showed the effectiveness of combining percutaneous transluminal angioplasty with stent deployment for significant renal artery stenosis to treat renovascular hypertension.

Adult↗