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E Paredes

Publications and source records attributed to E Paredes.

16 recordsLinked to original sources
PubMed2005

A new continuous calibration method for inductively coupled plasma spectrometry.

A new calibration method was developed and applied to inductively coupled plasma atomic emission spectrometry. External calibration was performed as follows. A container was filled with a given volume of deionized (V(p)) water. Then a concentrated standard was introduced at a controlled rate (Q(e)) into the tank by means of a peristaltic pump. The resulting solution was stirred throughout the experiment. Simultaneously, the solution inside the tank was pumped from the vessel to the plasma at a given rate (Q(s)). The signal was continuously recorded. The variation of the concentration of the solution leaving the tank with time was determined by applying a basic equation of stirred tanks. The representation of the emission intensity versus the time and the further conversion of the time scale into a concentration scale gave rise to the calibration line. The best results in terms of linearity were achieved for V(p)=15 cm3, Q(e)=0.6-0.75 ml min(-1) and Q(s)=1-1.2 ml min(-1). Graphs with more than 40 standards were obtained within about 10 min. The results found were not statistically different from those afforded by the conventional calibration method. In addition, the new method was faster and supplied better linearity and precision than the conventional one. Another advantage of the stirred tank was that procedures such as dynamic calibration and standard additions could be easily and quickly applied, thus shortening the analysis time. A complete analysis following these procedures based on the measurement of 30 standards took about 5 min. Several synthetic as well as certified samples (i.e., bovine liver, mussel tissue and powdered milk) were analyzed with the stirred tank by applying four different calibration methodologies (i.e., external calibration, internal calibration, standard additions and a combination of internal standardization and standard additions), with the combination of internal standardization and standard additions being the method that provided the best results. The element concentrations obtained were not significantly different from the actual or certified values.

Journal Article↗
PubMed2001

Reactions of 1-tosyl-3-substituted indoles with conjugated dienes under thermal and/or high-pressure conditions.

The behavior of 1-tosyl-3-acetylindole (1a), N,N-diethyl-1-tosyl-3-indoleglyoxylamide (1b), and 1-tosyl-3-nitroindole (1c) as dienophiles in Diels-Alder reactions under thermal and/or high-pressure conditions was explored with different dienes: isoprene (2), 1-(N-acetyl-N-propylamino)-1,3-butadiene (3), and 1-methoxy-3-trimethylsilyloxy-1,3-butadiene (Danishefsky's diene) (4). Compared to the acylated indoles, the nitro derivative proved to be the best dienophile. In general, the use of Danishefsky's diene led to high-yielding reactions under milder conditions. Likewise, high-pressure conditions proved to be better in producing high yields of products. The advantage of high-pressure over thermal conditions was the ability of the former to generate highly functionalized adducts in better yields, which were otherwise very difficult or impossible to obtain. The use of thermal or high-pressure conditions led to different regio- and/or stereoselectivity in the adducts, allowing control of the regio- or stereoisomer produced.

Journal Article↗
PubMed2000

Measuring living standards with proxy variables.

Very few demographic surveys in developing countries have gathered information on household incomes or consumption expenditures. Researchers interested in living standards therefore have had little alternative but to rely on simple proxy indicators. The properties of these proxies have not been analyzed systematically. We ask what hypotheses can be tested using proxies, and compare these indicators with consumption expenditures per adult, our preferred measure of living standards. We find that the proxies employed in much demographic research are very weak predictors of consumption per adult. Nevertheless, hypothesis tests based on proxies are likely to be powerful enough to warrant consideration.

Adult↗
PubMed1997

Cholera in Lima, Peru, correlates with prior isolation of Vibrio cholerae from the environment.

The authors utilized a recently developed DNA probe technique to obtain quantitative data on occurrence of Vibrio cholerae in samples collected monthly from 12 environmental sites in Lima, Peru, from November 1993 through March 1995. Peak V. cholerae counts ranged from 10(2)/ml to 10(5)/ml, with the highest counts in sewage-contaminated areas and irrigation water. With our methodology, no V. cholerae cases were detected at any site during the winter months of July through October. Counts were detectable in the environment before onset of cholera in the community, with counts at "cleaner" sites upriver correlating significantly with occurrence of community disease 2 and 3 months later. In sites with heavy sewage contamination, V. cholerae could still be detected before the onset of cases in the community; however, in contrast to upriver sites, counts at these latter sites correlated most closely with the number of concurrently occurring cholera cases. These data support a model of cholera seasonality in which initial increases in number of V. cholerae in the environment (possibly triggered by temperature) are followed by onset of illness in the community, with these human cases further amplifying the organism as the epidemic cycle proceeds.

Cholera↗
PubMed1997

Opioid availability in Latin America: the Santo Domingo report progress since the Declaration of Florianopolis.

The World Health Organization (WHO) has indicated that opioid analgesics are insufficiently available, particularly in developing countries, due to a variety of reasons, including legislative, educational, and policy issues. In its effort to promote the rational use of medical opioids and the adequate treatment of patients with cancer, WHO has sponsored a meeting of Latin American representatives every 2 years, which includes health professionals and government regulators. During March 24-27, 1996, a group of 86 representatives of cancer pain relief and palliative care programs from nine Latin American countries met in Santo Domingo under the auspices of the WHO Palliative Care Program for Latin America. For the first time since the First Latin American Meeting, government regulators were present to help address the issue of opioid availability from their perspective. During the meeting, issues pertaining to cancer pain, opioid availability, and palliative care were discussed. This report summarizes some of the events and presents a summary of the conclusions of an earlier meeting in 1994, as described in the Declaration of Florianopolis, and presents its follow-up, The Santo Domingo Report, generated following the 1996 meeting.

Analgesics, Opioid↗
PubMed1995

[A peripheral neuroectodermal tumor of the vulva].

A case of malignant peripheral neuroectodermal tumor occurring in the vulva of a 29-year-old woman is reported. It is a rare malignant tumor with aggressive biological behavior belonging to a wide group, the so-called small round-cell tumors. The patient is well and free of disease 8 months after surgery, chemotherapy and radiation therapy.

Adult↗
PubMed1992

Increased soluble CD4 and decreased soluble CD8 molecules in patients with Sjögren's syndrome.

PURPOSE: A new enzyme-linked immunosorbent assay for soluble CD4 (sCD4) and soluble CD8 (sCD8) molecules has been developed. We estimated the concentrations of these molecules in patients with Sjögren's syndrome and in patients with systemic lupus erythematosus (SLE) serving as a control population for non-Sjögren's inflammatory disease, since several findings suggestive of an aberration of immunocompetent cells have been reported in these autoimmune diseases. PATIENTS AND METHODS: The study population consisted of 41 patients with Sjögren's syndrome (28 cases of the primary form and 13 cases of the secondary form), 66 patients with SLE, and 43 normal individuals. Serum samples and clinical and laboratory data were collected from each patient and control. Assays of the sCD4 and sCD8 molecules were performed using an enzyme-linked immunosorbent kit developed by T Cell Science Inc., Cambridge, MA. RESULTS: The concentration of sCD4 was significantly increased in patients with both primary and secondary Sjögren's syndrome as compared with that in the control subjects. In contrast, sCD8 was significantly decreased in patients with primary disease but not in patients with secondary disease. A low or high concentration of sCD8 was significantly correlated with the presence of anti-SS-A antibody or hypocomplementemia, respectively. A similar significant correlation was noted between an increased sCD4 concentration and increased serum IgG level. In patients with SLE, the levels of both sCD4 and sCD8 were significantly increased. CONCLUSION: These observations represent the first evidence of an increased level of the sCD4 molecule and a decreased level of the sCD8 molecule and an association with immunologic abnormalities in Sjögren's syndrome. The increased and decreased levels of these soluble molecules observed may play a pathologic role in patients with Sjögren's syndrome.

Adult↗
PubMed1986

Spinal cord compression due to cystic duplication of the primitive digestive tract.

Three children are described who presented with the syndrome of spinal cord compression. They had intradural-extramedullary masses, which proved to be histologically benign cysts with characteristics similar to those found in the embryonic foregut. Emphasis is placed on the importance of early diagnosis and prompt surgical treatment of these congenital malformations, stressing the fact that complete recovery is possible. The literature is reviewed.

Child↗
PubMedDate not supplied

Gangliogliomas: clinical study and evolution.

We present 11 patients with intracranial gangliogliomas. The age ranged between 4 and 69 years with a mean of 32 years. The most frequent clinical manifestations were epilepsy in 7 cases and headache in 4 cases, and had begun from 15 days to 12 years before diagnosis. The gangliogliomas were located supratentorially predominantly in the temporal lobe (5 cases), except one, which was located within the cerebellum, which is extremely rare. EEG evidenced focality in 8 cases. The CT scan showed hypo or isodense images which were often associated with cysts, and that partially or totally enhanced with contrast administration in 7 cases (63.3%). Calcification was seen in only one case (9%). All our cases were treated surgically. Three patients were reoperated for recurrence. One case was reoperated twice and the histologic study showed astrocytoma grade II. Radiotherapy was given in two cases. In one case after subtotal surgery and in the other after the second operation for recurrence. Follow-up ranged between one and thirteen years, with a mean of 6.8 years. There was only one death. We used the CT scan for follow-up. However, nowadays MRI is more useful than the CT scan to distinguish recurrences.

Adult↗
PubMedDate not supplied

[Seroepidemiological investigation of various tissue helminthiasis, by means of indirect hemagglutination test, in Lonquimay County, Chile].

In order to have a present perspective on the prevalence on the epidemiology of some tissue helminthiasis in Lonquimay County, southern Chile, in 1993 a seroepidemiological survey, by means of an indirect hemagglutination test (IHAT) for hydatidosis, cysticercosis and trichinosis was undertaken. In 11 (1.2%), 10 (1.1%) and 6 (0.6%) out of 945 examined persons, most of them from rural areas, the corresponding IHAT resulted positive. Additionally, radiographic and ecotomographical studies for thorax and abdomen respectively were performed to the 11 individuals with serology positive for hydatidosis: whereas all the thoracic radiographies resulted negative, liver hydatic cysts were detected in five persons, who latter on were submitted to surgery. Prevalence rates of hydatidosis in Lonquimay are among the highest regional and national values.

Adolescent↗