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C Quintana

Publications and source records attributed to C Quintana.

At least 19 recordsLinked to original sources
PubMed2001

Elemental maps from EFTEM images using two different background subtraction models.

Acquisition of a great number of energy-filtered images in a TEM (EFTEM) around the characteristic signal with a low energy-selecting slit allows display of the electron energy loss (EEL)-spectrum of regions of interest (ROIs) of a sample. These EEL-spectra can be submitted to the different treatments already in use for electron energy loss spectroscopy (EELS). In particular, it is possible to fit the experimental background with different mathematical models, using images acquired below and above a characteristic ionization edge. After this fitting, elemental maps can be computed by subtraction of the extrapolated/interpolated background from the characteristic images. In this work, we compared two mathematical models for background fitting-the Egerton power law and the log-polynomial law. We studied the low-energy region (40-150 eV) and a higher-energy region (350-600 eV) with the aid of software for interactive processing of EFTEM image series that we developed. The analyzed elements were the constitutive elements: iron, phosphorus, nitrogen, and oxygen in several biological materials. Two analytical TEMs, one equipped with a post-column and the other with an in-column spectrometer, were used. Our experimental results confirm that the power law is very sensitive to the value of the energy loss of the pre-edge images when the background is computed by extrapolation. The log-polynomial model is less sensitive than the power law model to the value of the energy loss of the pre-edge images in the low energy region. For the oxygen K edge at 535 eV, it gives the best fit when it is combined with the interpolation method. The use of programs that facilitate the handling of EFTEM image series, and the controlled calculation of the background under the characteristic images, represent a step forward in the generation of elemental maps.

Animals↗
PubMed2000

Initial studies with high resolution TEM and electron energy loss spectroscopy studies of ferritin cores extracted from brains of patients with progressive supranuclear palsy and Alzheimer disease.

Studies of crystallographic structure and composition of core nanocrystals of ferritin bound to aberrant tau filaments extracted from progressive supranuclear Palsy (PSP) and Alzheimer disease (AD) brain tissues were performed using high resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS). The results were compared with those obtained from synthetic Fe3O4 crystal (magnetite) and horse spleen ferritin cores. Core dimensions of ferritin molecules from PSP and AD were similar to those found in normal brain. Ferritin cores nanocrystals in AD seems to have less ordered structure than in PSP. Some nanocrystals did not have the hexagonal ferrihydrite structure generally found in healthy ferritin but rather a cubic structure similar to magnetite, a crystalline form in which both Fe2+ and Fe3+ are present. The presence of ferrous ion, Fe2+, may indicate some dysfunction in these pathological ferritins that might contribute to production of free radicals via the Fenton reaction involved in neurodegeneration.

Alzheimer Disease↗
PubMed1998

Optimization of phosphorus localization by EFTEM of nucleic acid containing structures.

Energy Filtered Transmission Electron Microscopy (EFTEM) has been used to study nucleic acids localization in unstained thin sections of virus-infected cells. For this purpose, phosphorus maps (P-maps) have been obtained by applying the N-windows Egerton model for background subtraction from data acquired by a non-dedicated TEM Jeol 1200EXII equipped with a post-column PEELS Gatan 666-9000 and a Gatan Image Filter (GIF-100). To prevent possible errors in the evaluation of elemental maps and thus incorrect nucleic acid localization, we have studied different regions of swine testis (ST) cells with similar local density containing either high concentration of nucleic acids (condensed chromatin and ribosomes) or a very low concentration (mitochondria). Special care was taken to optimize the sample preparation conditions to avoid as much as possible the traditional artifacts derived from this source. Selection of the best set of pre-edge images for background fitting was also considered in order to produce "true P-maps". A new software for interactive processing of images series has been applied to estimate this set. Multivariate Statistical Analysis was used as a filtering tool to separate the "useful information" present in the inelastic image series (characteristic signal) from the "non-useful information" (noise and acquisition artifacts). The reconstitution of the original image series preserving mainly the useful information allowed the computation of P-maps with improved signal-to-noise ratio (SNR). This methodology has been applied to study the RNA content of maturation intermediate coronavirus particles found inside infected cells.

Animals↗
PubMed1998

Ferritin is associated with the aberrant tau filaments present in progressive supranuclear palsy.

Tau-containing filaments purified from the brain of progressive supranuclear palsy (PSP) patients were isolated and characterized. These filaments co-purify with regular particles that biophysical and biochemical methods identified as ferritin shells. In vivo, brain tau accumulation in PSP co-localized with ferritin. These results suggest that ferritin/iron could modulate the formation of tau aggregates in PSP.

Brain↗
PubMed1998

[Ulcerative colitis and pregnancy].

BACKGROUND: The evolution of ulcerative colitis in pregnancy is far from clear. While some authors state that the disease aggravates during this period, others do not share this opinion. AIM: To assess the evolution of ulcerative colitis in pregnancy. PATIENTS AND METHODS: A paired case-control design was used in which 15 women, with diagnosed ulcerative colitis at the moment of becoming pregnant, were followed for 12 months and the activity of the disease was compared with that of the 12 months preceding the pregnancy. The activity of the disease in the period preceding the pregnancy was gathered retrospectively from the patient's charts. RESULTS: The mean age of the first ulcerative colitis crisis was 24 years. It was moderate in 49% and severe in 35% of women. During pregnancy 55% of women did not have a crisis, compared with 26.7% during the period preceding pregnancy (relative risk of not having a crisis during pregnancy of 1.7). During both periods, seven women had digestive complications, whereas extra digestive complications were not observed in 60% of patients during pregnancy and 11.8% of patients during the preceding period. Perinatal results were similar to those of the general population. CONCLUSIONS: In our group of patients the evolution of ulcerative colitis was better during pregnancy, reflected by a lower number of crisis.

Colitis, Ulcerative↗
PubMed1998

[Enteral nutrition in severe ulcerative colitis. Digestive tolerance and nutritional efficiency].

BACKGROUNDS AND AIMS: Total parenteral nutrition (TPN) has been traditionally used as an adjunctive therapy in severe ulcerative colitis patients. We performed a prospective study to ascertain the safety, nutritional efficiency, tolerance and costs of total enteral nutrition in this situation. METHODS: After 48 hours of intensive medical treatment, severe ulcerative colitis patients initiated enteral feeding with a polymeric formula. The formula concentration and volume were increased daily. RESULTS: 17 patients (7 women, 10 men; age 36.8 +/- 12.8 years) with a mean clinical activity score of 15.6 +/- 1.5 were included. In 14 patients (82.4%) enteral nutrition was well tolerated, attaining in 11 of them more than 80% of the caloric requirements by day 4. In 3 cases we observed vomiting and bloating. Prealbumin levels improved significantly from 11.1 +/- 3.4 mg/dl to 22.7 +/- 6.8 mg/dl (p = 0.002) at the end of enteral nutrition (11.8 +/- 4.7 days). Albumin and other nutritional parameters did not change. CONCLUSIONS: Total enteral nutrition could be considered a safe and well tolerated nutritional support in these patients. Although albumin and other nutritional parameters did not change during the study period, the increase in prealbumin levels suggests a favourable anabolic effect of total enteral nutrition.

Adolescent↗
PubMed1997

[Evaluation of sensitivity, specificity and predictive value of six qualitative serological methods for the detection of Helicobacter pylori antibodies].

Screening tests for IG g antibodies against Helicobacter pylori are usefull for a long follow up of patients who were well eradicated. The aim of this study was to determinate and compared sensibility, specificity, positive and negative predictive value of six qualitative serological tests for IG g antibodies detection in the diagnosis of H. Pylori infections. Between May and October 1996 52 patients (30 males and 22 females; median age 42.4 years, range 21-68) with H. Pylori infection assessed on two antral and two corpus biopsies by means of Giema stain and a rapid urease test were tested for IG g antibodies detection. The serological tests used were: Inmunocomb II (Orgenics) Enzimo Inmuno Assay Inmunoadsorbent qualitative, Flex Pack (Smith Kline Diagnostics, Abbott) inmunocromatographic cualitative, Pylori Stat test (Biowhittaker) Enzimo Inmuno Assay (ELISA) qualitative, Premier (Meridian Diagnostics) Enzimo Inmuno Assay ELISA) qualitative. Pyloristest (Orion Diagnóstica) latex aglutination qualitative, H. Pylori (Bio Tre) Enzimo Inmuno Assay cualitative. 10 healthy subjects with negative gastric biopsies and negative rapid ureasa test were used as control group. The six evaluated serological tests have a comparable sensibility (89-95%) and specificity (77-83%) for the diagnosis of HP infection. The presence of specific HP antibodies in infected patients revealed a strong correlation with the histological demonstration of the microrganisms. We can recommend this qualitative serological tests due to their high sensibility and specificity, simplicity and low cost.

Adult↗
PubMed1996

Looking for the artery of Adamkiewicz: a quest to minimize paraplegia after operations for aneurysms of the descending thoracic and thoracoabdominal aorta.

All patients undergoing resection of thoracic or thoracoabdominal aneurysms at Mount Sinai Hospital since November 1993 had spinal cord function monitored with somatosensory-evoked potentials as part of a multimodality approach to reducing spinal cord injury. In the segment to be resected, each pair of intersegmental vessels was sequentially clamped, and they were subsequently sacrificed only if no change in somatosensory evoked potentials occurred within 8 to 10 minutes after occlusion. Adjunctive protective measures included mild hypothermia (31 degrees to 33 degrees C), distal perfusion, corticosteroids, maintenance of high normal blood pressures, avoidance of nitroprusside, and cerebrospinal fluid drainage. Ninety-five consecutive patients operated on since 1993 (group II) were compared with 138 earlier patients (group I). Preoperative characteristics such as age, sex, etiology of aneurysm, emergency operation, and reoperation did not differ between groups, nor did operative variables such as incidence of rupture and extent of resection. Group I had slightly more smokers and slightly fewer hypertensive individuals. Group II patients had a significantly better outcome with respect to in-hospital mortality (10.5% vs 18%, p = 0.045) and paraplegia (2% vs 8%, p = 0.008). By multivariate analysis, rupture and diabetes were associated with significantly higher in-hospital mortality, and smoking greatly increased the incidence of paraplegia. The extent of the aneurysm was a major determinant of mortality and paraplegia. The low paraplegia rate in group II was achieved without reattachment of a single intercostal or lumbar artery. No patient with fewer than 10 intersegmental arteries severed had paraplegia, and spinal cord ischemia was reversible in three patients after adjunctive maneuvers were performed to improve perfusion, suggesting that spinal cord blood supply is unlikely to depend on a single "artery of Adamkiewicz."

Aged↗
PubMed1995

Differences between nuclear run-off and mRNA levels for multidrug resistance gene expression in the cephalocaudal axis of the mouse intestine.

P-glycoprotein is a multidrug transporter encoded by the mdr3 gene in the mouse intestinal epithelium. The aims of this study were to characterize the mdr3 gene expression in the cephalocaudal axis of the intestine in adult animals and during perinatal development, and to define the molecular mechanism responsible for the heterogeneous expression of the gene along the cephalocaudal axis. RNA extracted from stomach, duodenum, jejunum, ileum, cecum and colon was hybridized by slot blot and Northern blot using a mdr3 cDNA probe. The regulation of gene expression was investigated examining the rate of transcription by nuclear run-off analysis. Transport studies of rhodamine 123, a substrate of P-glycoprotein, were performed in everted jejunum and ileum. The level of mdr3 mRNA and P-glycoprotein found in ileum was 6-fold higher than the level found in duodenum. The regional pattern of mdr3 gene expression is established in the intestine of 10-day-old animals. Similar mdr3 hybridization signal in nuclear run-off assay was found in nuclei of enterocytes isolated from jejunum and ileum, suggesting that the heterogeneous expression of the mdr3 gene in the cephalocaudal axis of the small bowel may be predominantly regulated at the post-transcriptional level. Transport rate of rhodamine 123 from the serosal to mucosal side in everted ileum was higher than the rate of transport found in jejunum. These results indicate that enterocytes of the ileum may be more actively involved in the P-glycoprotein-mediated transport of xenobiotics into the intestinal lumen.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1995

Treatment of acute infantile diarrhoea with a commercial rice-based oral rehydration solution.

This randomized clinical trial compared the efficacy of an oral rehydration solution (ORS) formulated with commercial rice powder, 50 g/l, with that of a glucose-based WHO/UNICEF-recommended ORS in the management of 48 inpatients aged 3-24 months, with acute dehydrating watery diarrhoea. Stool outputs were generally high in these patients, and 11 patients (22%) required additional intravenous rehydration solutions. The stool output (ml/kg) in the first 24 hours was [geometric mean, (95% confidence intervals)] 213 (153-353) in the rice-ORS group versus 146 (108-232) in the glucose-ORS group, while the total stool output was 455 (298-933) versus 307 (209-625); (p value not significant). The mean (+/- SD) duration of diarrhoea in hospital was: 72 +/- 10 hours in the study group versus 77 +/- 12 hours in the control group (p value NS). Enteropathogens were found in 94% of the patients, rotavirus being prevalent in 85% of the cases. It is concluded that the rice-ORS used in this trial is no more efficacious than the standard glucose-ORS advocated by WHO/UNICEF in the treatment of infants with watery non-cholera dehydrating diarrhoea. In some cases, ORS formulated with the commercial cereal-based products might actually increase the stool losses in infants with high-output non-cholera diarrhoea.

Acute Disease↗
PubMed1994

Cryofixation, cryosubstitution, cryoembedding for ultrastructural, immunocytochemical and microanalytical studies.

Cryofixation, cryosubstitution and cryoembedding are a set of low-temperature methods for immunocytochemical and microanalytical ultrastructural studies. This review covers the theoretical and practical aspects of these cryomethods, simple, low-cost, safe devices that provide reproducible results and a summary of recent results. Sections prepared by these three cryomethods can be used to determine elemental composition, molecular composition, functions and 3-D ultrastructure. The information obtained can be treated by multivariate statistical methods. Thus, each cellular compartment can be identified by its morphology, molecular and elemental composition and function and changes in these data during physiological and pathological processes can be monitored.

Acrylic Resins↗
PubMed1994

The ascending aorta: how much does transesophageal echocardiography see?

We assessed the ability of transesophageal echocardiography (TEE) to examine the entire length of the ascending aorta. TEE-derived data were compared with anatomic measurements and epiaortic scanning. There were 27 patients (19 male, 8 female; aged 67 +/- 12 yr) studied during cardiac surgery. The surgeon measured the distance between the aortic anulus near the right coronary artery to the origin of the innominate artery (AV-->IN) and to the level of the aortic cannulation site (AV-->C). Independently, the ascending aorta was imaged by biplane TEE and the maximum length of aorta visualized was measured (TEE-MAX). Additionally, TEE was used to detect atheromas in the aorta and to visualize the aortic cannula. Epiaortic scanning was also performed in 14 patients. Direct measurement of the ascending aorta revealed a length of 8.9 +/- 1.3 cm (mean +/- SD) and the TEE-MAX was 7.4 +/- 1.1 cm. The range of the difference between the two measurements was 0.2-4.5 cm. The aortic cannula was visualized only in 1 of 27 patients, and severe atherosclerotic plaques (> 3 mm thick), not seen on TEE, were detected in five patients with epiaortic scanning. As much as 42% (4.5 cm of 10.7 cm) of the length of the ascending aorta was not visualized and potentially embolic plaques were not imaged by TEE. These findings suggest that even biplane TEE may have limited use in the precannulation assessment of the aorta for plaque and the detection of distal ascending aortic pathology.

Aged↗
PubMed1994

Improvements in biological X-ray microanalysis: cryoembedding for specimen preparation and multivariate statistical analysis for data interpretation.

For biological X-ray microanalysis, cryoembedding (CE) combined with cryofixation (CF) and cryodehydration (CD) was already proposed as an alternative method to freeze-dried cryosections in 1984 by Wróblewski and Wroblewski. CD by freeze-drying (FD) is usually recommended because it provides better retention of diffusible elements. CD by freeze-substitution (FS) has the advantage of being simpler, giving more reproducible preservation of ultrastructure and causing fewer problems for resin infiltration. We have increased the retention of diffusible elements by using home-made devices for CS and CE in the new Lowicryl K11M and HM23 resins. These resins allow samples to be kept at a maximum temperature of 213K and 193K respectively. Application of multivariate statistical analysis (MSA) to X-ray data (spectra and maps) allows the study of correlations between the analyzed elements in different nuclear areas and in the cytoplasm. The "factorial" images, obtained with MSA, display the compartments of strong correlation between P and K (nucleic acids) and the compartments of strong correlation between S and K (proteins). We suggest that the future application of MSA methods will provide increased knowledge of the physio-pathological compartmentation of diffusible elements at the subcellular level.

Animals↗
PubMed1994

Multivariate statistical analysis applied to X-ray spectra and X-ray mapping of liver cell nuclei.

Principal Components Analysis (PCA) and Factorial Analysis of Correspondence (FAC), two Multivariate Statistical Analyses (MSA), were applied to the analysis of X-ray data. MSA are descriptive methods which graphically display the correlations and anticorrelations between a large number of elements. Series of X-ray spectral data and X-ray maps obtained from rat liver were analyzed with reference to the diffusible elements Na, Mg, Cl, K and Ca and also P and S. By using an in situ precipitation method, the pyroantimonate method, it was found that the free, precipitable cations Na+, Mg2+, and Ca2+ are, in the nuclei, mainly distributed throughout the nucleoplasm. Images obtained from FAC allow those areas rich in nucleic acids to be displayed as areas with a strong anticorrelation between P and Sb. In cryoprocessed tissues, the evaluated wet mass-fraction of diffusible elements corresponds to physiological values of total amounts (free and complexed). PCA makes it possible to graphically display the correlation between P and K in chromatin and nucleolus, the correlation between K, Cl and S in cytoplasm and nucleoplasm and the observation of two populations of nuclei according to different Na, Mg and K concentrations. Factorial images obtained from FAC allow those areas rich in nucleic acids to be displayed as areas with a strong correlation between P and K. Similarly those areas rich in proteins are displayed as areas with a strong correlation between S and K.

Animals↗
PubMed1994

Hypothermic circulatory arrest in operations on the thoracic aorta. Determinants of operative mortality and neurologic outcome.

This study was undertaken to determine the factors that influence the final outcome after hypothermic circulatory arrest. Between 1985 and 1992 a uniform method of hypothermic circulatory arrest was used in 200 patients as the primary method of cerebral protection during operations on aneurysms of the thoracic aorta. There were 30 hospital deaths (15%). Age greater than 60 years (relative risk 3.7, p < 0.02), emergency operation and hemodynamic compromise (relative risk 22.2, p < 0.000), concomitant procedures (relative risk 2.7, p < 0.04), presentation with new neurologic symptoms (relative risk 5.2, p < 0.04), and postoperative permanent neurologic deficits (relative risk 9.4, p < 0.000) were found to be significant predictors of operative mortality. A total of 183 patients were available for evaluation of neurologic function and outcome. Multivariate analysis of this cohort of patients by multiple logistic regression showed that temporary neurologic dysfunction occurred in 36 cases (19%). Temporary neurologic dysfunction correlated with the duration of hypothermic circulatory arrest (47 +/- 16 minutes; odds ratio 1.06/minute; p < 0.001) and age (66 +/- 14 years; odds ratio 1.07/year; p < 0.001). Embolic strokes occurred in 22 patients (11%) and were associated with permanent deficits in 13 (7%). Strokes correlated significantly with age (older than 60, 21% versus younger than 60, 1%; p < 0.001) and operations on the arch and descending aortic aneurysms containing clot or atheroma (p < 0.001). This experience shows that the operative mortality is not affected by any parameters related to the use of hypothermic circulatory arrest. The incidence of temporary neurologic dysfunction rises linearly in relation to the age of the patient and the duration of hypothermic circulatory arrest. However, permanent neurologic injury is a result of thromboembolic events and is not related to the method of cerebral protection used. Additional methods to prevent perioperative embolic strokes are needed. Hypothermic circulatory arrest affords adequate cerebral protection if the arrest period is kept less than 60 minutes. We will continue to use this modality until the safety and utility of the alternate methods of cerebral protection are shown to be superior.

Aortic Dissection↗
PubMed1994

The natural history of thoracic aortic aneurysms.

Because improved understanding of the natural history of thoracic aneurysms would enhance our ability to determine in which cases the risk of surgical treatment is justified, the rate of enlargement of thoracic aneurysms and thoracoabdominal aneurysms was studied in 67 patients by means of serial computer-generated three-dimensional reconstructions of computed tomographic scans. Patients were followed for a mean of 1.5 +/- 0.15 years (0.2 to 5.35 years) with an average interval between examinations of 0.9 +/- 0.1 year (0.2 to 5.0 years). Thirty-nine patients continue to be followed; 7 were lost to follow-up; 14 died during follow-up (4 after aneurysm rupture), and 10 underwent an operation. Indications for operation included the presence of pain, an absolute aortic diameter larger than 8 cm, an increase in aortic diameter of more than 1 cm per year, or marked irregularity of aneurysm contour. Aortic diameter and volume data were generated from the aortic silhouette obtained by tracing each computed tomographic slice with a translucent digitizing tablet. Estimated change in aortic diameter after 1 year was 0.43 cm; estimated change in aortic volume was 88.1 ml. The impact of possible risk factors on the enlargement of aneurysms was examined by analysis of variance (p < 0.05). A significantly higher rate of aneurysm expansion was found in patients with a larger aortic diameter (> 5 cm) at diagnosis (change in diameter = 0.17 cm versus 0.79 cm; change in volume = 40 ml versus 141.8 ml), and in smokers (change in diameter = 0.35 cm versus 0.70 cm; change in volume = 78.3 ml versus 120.8 ml). Changes in diameter and volume for aneurysms of different initial diameters and volumes was predicted by exponential regression by the equations: change in diameter = 0.0167 (initial aortic diameter)2.1; change in volume = 0.0356 (initial aortic volume)1.322. No correlation was noted between the rate of enlargement and age, sex, or the presence of dissection. A history of hypertension correlated with a greater aortic diameter at diagnosis but did not significantly affect the rate of enlargement.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗