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Biomedical subjects

E Morales

Publications and source records attributed to E Morales.

At least 37 records · Page 2Linked to original sources

Sample treatment in chromatography-based speciation of organometallic pollutants.

Speciation analysis is nowadays performed routinely in many laboratories to control the quality of the environment, food and health. Chemical speciation analyses generally include the study of different oxidation state of elements or individual organometallic compounds. The determination of the different chemical forms of elements is still an analytical challenge, since they are often unstable and concentrations in different matrices of interest are in the microg l(-1) or even in the ng l(-1) range (e.g., estuarine waters) or ng g(-1) in sediments and biological tissues. For this reason, sensitive and selective analytical atomic techniques are being used as available detectors for speciation, generally coupled with chromatography for the time-resolved introduction of analytes into the atomic spectrometer. The complexity of these instrumental couplings has a straightforward consequence on the duration of the analysis, but sample preparation to separate and transfer the chemical species present in the sample into a solution to be accepted readily by a chromatographic column is the more critical step of total analysis, and demands considerable operator skills and time cost. Traditionally, liquid-liquid extraction has been employed for sample treatment with serious disadvantages, such as consumption, disposal and long-term exposure to organic solvent. In addition, they are usually cumbersome and time-consuming. Therefore, the introduction of new reagents such as sodium tetraethylborate for the simultaneous derivatization of several elements has been proposed. Other possibilities are based in the implementation of techniques for efficient and accelerated isolation of species from the sample matrix. This is the case for microwave-assisted extraction, solid-phase extraction and microextraction, supercritical fluid extraction or pressurized liquid extraction, which offer new possibilities in species treatment, and the advantages of a drastic reduction of the extraction time and the embodiment into on-line flow analysis systems. This new generation of treatment techniques constitutes a good choice as fast extraction methods for feasible species-selective analysis of organometallic compounds under the picogram level, that can be used for national regulatory agencies, governmental and industrial quality control laboratories, and consequently, for manufacturers of analytical instrumentation.

Chromatography↗

The contribution of dendritic Kv3 K+ channels to burst threshold in a sensory neuron.

Voltage-gated ion channels localized to dendritic membranes can shape signal processing in central neurons. This study describes the distribution and functional role of a high voltage-activating K(+) channel in the electrosensory lobe (ELL) of an apteronotid weakly electric fish. We identify a homolog of the Kv3.3 K(+) channel, AptKv3.3, that exhibits a high density of mRNA expression and immunolabel that is distributed over the entire soma-dendritic axis of ELL pyramidal cells. The kinetics and pharmacology of native K(+) channels recorded in pyramidal cell somata and apical dendrites match those of AptKv3.3 channels expressed in a heterologous expression system. The functional role of AptKv3.3 channels was assessed using focal drug ejections in somatic and dendritic regions of an in vitro slice preparation. Local blockade of AptKv3.3 channels slows the repolarization of spikes in pyramidal cell somata as well as spikes backpropagating into apical dendrites. The resulting increase in dendritic spike duration lowers the threshold for a gamma-frequency burst discharge that is driven by inward current associated with backpropagating dendritic spikes. Thus, dendritic AptKv3.3 K(+) channels influence the threshold for a form of burst discharge that has an established role in feature extraction of sensory input.

Action Potentials↗

Neosporosis in Mexican dairy herds: lesions and immunohistochemical detection of Neospora caninum in fetuses.

Of 211 aborted bovine fetuses collected from Mexican dairy herds between January 1996 and March 1999, 73 showed microscopical lesions consistent with neosporosis. Of these 73 fetuses, 58 (79%) showed lymphocytic myocarditis, 39 (53%) showed microgliosis and multifocal necrosis in the brain, 39 (53%) showed lymphocytic hepatitis, and 19 (26%) showed lymphocytic myositis. Immunohistochemical examination of brain, myocardium and liver from 53 of the same 73 fetuses demonstrated Neospora caninum antigens in 41 (77%), of which 19 (46%) gave positive results in one of the three sites, 15 (37%) in two, and seven (17%) in three. The results indicated the presence of neosporosis in a number of the main dairy farming regions of Mexico.

Abortion, Veterinary↗

Clinical features and long-term outcome of obesity-associated focal segmental glomerulosclerosis.

BACKGROUND: Several cases of obesity-associated focal segmental glomerulosclerosis (OB-FSG) have been reported but little is known about the clinico-pathological features of this entity and its long-term outcomes. METHODS: We studied 15 obese patients (BMI 35+/-5.2 kg/m(2)) with biopsy-proven FSG. They were compared with a control group of 15 non-obese patients with idiopathic FSG (I-FSG). RESULTS: Mean proteinuria at the time of renal biopsy was 3.1+/-2 g/24 h in OB-FSG; it reached the nephrotic range (> or =3.5 g/24 h) during follow-up in 12 patients (80%), but none of them had oedema, hypoproteinaemia, or hypoalbuminaemia. Proteinuria was more marked amongst I-FSG (6.5+/-4.2 g/24 h) and most of them developed oedema and biochemical nephrotic syndrome. Glomerulomegaly was observed in all renal biopsies from OB-FSG patients (mean glomerular diameter 256+/-24 microm in OB-FSG vs 199+/-26 microm in I-FSG, P<0.001). Twelve OB-FSG patients (80%) were treated with ACE inhibitors (ACEI) and proteinuria significantly decreased within the first 6 months of treatment but showed a later increase. None of the obese patients achieved a sustained weight loss. Seven (46%) patients with OB-FSG experienced a progressive renal insufficiency and five of them started intermittent dialysis. Kaplan-Meier estimated probabilities of renal survival after 5 and 10 years were 77 and 51%, respectively, in OB-FSG patients, and 52 and 30% in I-FSG (P<0.05). The risk of developing progressive renal failure among OB-FSG patients was statistically correlated with serum creatinine and creatinine clearance at presentation. CONCLUSIONS: OB-FSG indicates a poor prognosis with almost one-half of patients developing advanced renal failure. Knowledge of the clinico-pathological features of this entity (obesity, FSG lesions with glomerulomegaly, absence of nephrotic syndrome despite nephrotic-range proteinuria) should be helpful in establishing an accurate and early diagnosis.

Adult↗

Seroprevalence study of bovine neosporosis in Mexico.

An indirect enzyme-linked immunosorbent assay was used to obtain epidemiologic information on bovine neosporosis in dairy herds of the Mexican central plateau. Sera were collected from 1,003 cows from 50 dairy herds. Forty-three herds (group A) had been experiencing a high abortion rate. The abortion rates for the remaining 7 herds (group B) were within normal limits for Mexico. Five-hundred sixty-one (56%) of the 1,003 sera were positive. The seroprevalence of Neospora caninum antibodies was 72% (95% CI = 68-75%) in group A and 36% (95% CI = 31-40%) in group B. These results clearly show that infection with N. caninum is widespread in Mexican dairy herds, as indicated by seropositive cows in group A and group B herds at the time of the sample collection.

Animal Husbandry↗

Column-switching system for selenium speciation by coupling reversed-phase and ion-exchange high-performance liquid chromatography with microwave-assisted digestion-hydride generation-atomic fluorescence spectrometry.

Speciation of selenocysteine (SeCys), selenomethionine (SeMet), selenoethionine (SeET), selenite (Se(IV)) and selenate (Se(VI)) has been accomplished using high-performance liquid chromatography, with the aid of an anion exchange column and a reversed-phase column, both connected through a six-port switching valve. On-line microwave-assisted digestion and hydride generation steps were performed prior to the atomic fluorescence detection. The elution of the seleno amino acids was accomplished in the reversed-phased column using water as mobile phase. Selenite and selenate were separated in the anion exchange column, using gradient elution with an acetate buffer. The separation of the five selenium compounds took place in 15 min. The detection limits obtained ranged between 0.6 and 0.9 microg l(-1). Values of r>0.998 were obtained for linear fit graphs. A commercial available urine sample was analyzed, in which SeCys and Se(IV) were quantified.

Chromatography, High Pressure Liquid↗

Double versus single renal allografts from aged donors.

BACKGROUND: The age limit of the cadaver kidney donors is increasing in response to the growing demand for renal transplantation. Simultaneous double kidney transplantation (SDKT) with kidneys obtained from elderly adults has been proposed to increase the transplantation number and improve its results. However, if SDKT is performed when there are no clear indications, a negative effect could be produced on the total number of transplanted patients as both kidneys would be used for only one recipient. MATERIAL AND METHODS: In December 1996 we designed a transplantation protocol to be able to extend the selection of cadaver kidney donors with normal serum creatinine levels without establishing any age limit. A pregraft renal biopsy was always performed to analyze the glomerulosclerosis (GE) percentage whenever the donors were 60 years of age or older. A SDKT was performed in a single recipient when the donor age was 75 years or older or when the donors between 60 and 74 years old had a GE rate of more than 15%. On the contrary, a single kidney transplantation was performed in two different recipients for kidneys from donors between 60 and 74 years of age with a GE rate of less than 15%. Kidneys having GE rates of more than 50% were discarded for transplantation. Donor kidneys from subjects younger than 60 years of age were always used for a single kidney transplantation. RESULTS: Based on the above mentioned protocol, from December 1996 to May 1998, 181 patients received a kidney transplantation in our hospital. These patients were divided into three groups: group I which included the SDKT recipients (n=21), group II or single kidney recipients from 60- to 74-year-old donors (n=40), and group III or recipients from <60-year-old donors (n=120). The mean follow-up time was 15+/-5 months (range 6-24). Mean donor age was 75+/-7 years in group I, this was significantly higher than in group II (67+/-4, P<0.001) and group III (37+/-15, P<0.001). The primary nonfunction rate was low in the three groups, there being no statistically significant differences (5, 5, and 4%, respectively). A significantly greater percentage of patients from group I (76%) presented immediate renal graft function as compared with group II (43%, P<0.01) and III (50%, P<0.05). The acute rejections rate was very low in all three groups (9.5, 7.5, and 22%, respectively) with significant differences between groups II and III (P<0.05). No significant differences between the different groups were observed for one year actuarial patient survival (100, 95, and 98%, respectively) or graft survival rates (95, 90, and 93%, respectively). The 6-month serum creatinine levels were excellent in the three groups, although there were significant differences between groups I and II (1.6+/-0.3 vs. 1.9+/-0.6 mg/dl, P<0.05), II and III (1.9+/-0.6 vs. 1.4+/-0.4 mg/dl, P<0.001), and I and III (P<0.05). CONCLUSIONS: Simultaneous double kidney transplantations make it possible to use kidneys from extremely elderly donors (>75 years) or those whose GE>15%. In addition, kidneys from donor 60-74 years old in which the GE<15% can be used for single kidney transplantations in two different recipients with excellent results.

Adult↗

Comparison of the feasibility of three extraction procedures for trace metal partitioning in sediments from south-west Spain.

The feasibility of three sequential extraction schemes (a modification of the Tessier procedure, the scheme proposed by Meguellati and the protocol designed by BCR (now called the Standards, Measurements and Testing Programme, M&T) have been compared to study the distribution of As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn in sediment samples. The comparison has been performed by analyzing Certified Reference Material (CRM-601), a test material (S-12) and seven sediments from the Odiel Marshes Natural Park (located at the Atlantic coast of southern Spain). Samples were classified as sandy (with low iron oxide and organic matter contents) and clay-silty (with high iron oxide and organic matter contents) sediments. A higher metal mobility, especially under reducing conditions, was more properly assessed using the modified Tessier scheme compared to both the BCR and Meguellati procedures, these two later presenting comparative results for the reducible and residual phases. Significant Hg losses were found using the BCR procedure but the quantification of the acid phase for Cd, Cr and Ni was more reliable than that obtained with the modified Tessier and Meguellati schemes.

Environmental Monitoring↗

Temporal fluctuations of tributyltin in the bivalve Venerupis decussata at five stations in southwest Spain.

Filter feeding clams, Venerupis decussata, were sampled every 4 months for 8 years at five locations on the southwest Spain coast and analysed for organotins. All the stations showed a significant sinusoidally shaped seasonal evolution pattern for tributyltin (TBT) superimposed upon a linear decreasing tendency. The amplitude and frequency of fluctuations differed among stations and were correlated to the harbour activities. Fluctuations were greatest at stations with the greatest TBT presence. The long-term trend of TBT in clams indicated half-life values of about 7-14 years. During 1993, water and sediment samples were also collected at monthly intervals and analysed. Correlations between TBT bivalve contents and water concentrations were higher than those found between biota and sediments.

Journal Article↗

Secondary (AA-type) amyloidosis in patients with polymyalgia rheumatica.

Several cases of systemic amyloidosis associated with polymyalgia rheumatica (PMR) or giant-cell arteritis (GCA) have been described. Nevertheless, the type of amyloid deposit has not been characterized in most of them. Here we report on two patients with PMR (one with associated GCA) who developed nephrotic syndrome and end-stage renal failure caused by massive amyloid deposition. Immunohistochemical analysis showed that the amyloid deposits were of AA type (secondary amyloidosis) in both cases.

Aged↗

Familial microscopic hematuria caused by hypercalciuria and hyperuricosuria.

We report 12 patients belonging to five different families in whom persistent isolated microhematuria was associated with hypercalciuria and/or hyperuricosuria. Four patients had episodes of gross hematuria, three patients had passed renal stones, and a history of nephrolithiasis was obtained in four of the families (80%). Calcium oxalate and uric acid crystals were commonly observed in the urine sediments. Urinary erythrocytes had a normal appearance on phase-microscopic examination. Reduction of calciuria and uricosuria by thiazide diuretics, allopurinol, forced fluid intake, and dietetic measures led to a persistent normalization of urine sediment with complete disappearance of hematuria. Determination of calcium and uric acid urinary excretions should be included in the study of familial hematuria.

Adolescent↗

Self-efficacy and HIV-related risk behaviors among multiethnic adolescents.

A cross-sectional correlational design was used to investigate (a) self-efficacy and risk behaviors related to HIV; (b) the comparative predictiveness of self-efficacy and knowledge, attitudes, and beliefs regarding sexual activity and substance use; and (c) possible risk profiles for HIV among adolescents. High school students (N = 427), ranging in age from 12 to 20 years and attending Family Life Education classes in Alameda, California, volunteered to complete a self-administered questionnaire, resulting in a 73% response rate. Ethnic representation included African American, Chinese, Filipino, other Asian/Pacific Islander, Latino, and European American. Over half of this sample of teens were sexually active by the age of 14, with sexually active teens and substance-using teens scoring higher on HIV knowledge, attitudes, and beliefs regarding HIV-related behaviors. Ethnicity consistently appeared more significant in predicting these risk behaviors than gender, self-efficacy, and knowledge, attitudes, and beliefs. The predominance of ethnicity as the predictor for these HIV risk behaviors indicates that theoretical models for behavior change must include a dimension of culture, diversity, and ethnic identity.

Adolescent↗

Schulzia chiribita n. sp. (Nematoda, Trichostrongylina, Molineoidea) parasite of Leptodactylus rhodonotus (Amphibian) from Peru.

A third species of the genus Schulzia Travassos, 1937 a parasite of Leptodactylus rhodonotus (Amphibian, Leptodactylidae) originating from Peru is described. By the pattern of the caudal bursa, the specimens are closely related to the two other species. They are distinguished from Schulzia uzu Lent & Santos, 1989, parasite from Atelopus oxyrhynchus in Venezuela, by the shape of the ovejector and from Schulzia travassosi Durette-Desset, Baker & Vaucher, 1985, parasite from Bufo crucifer in Brasil, Bufo granulosus and Leptodactylus bufonius in Paraguay, by the shape of the spicules. The presence of a new species in Peru points out the wide geographic distribution of the genus in the Neotropical region.

Animals↗

Estimating phylogenetic inertia in Tithonia (Asteraceae): a comparative approach.

Phylogenetic inertia is a difficult issue in evolutionary biology because we have yet to reach a consensus about how to measure it. In this study a comparative approach is used to evaluate phylogenetic inertia in 14 demographic and morphological characters in 10 species and one subspecies of the genus Tithonia (Asteraceae). Three different methods, autocorrelational analysis, phylogenetic correlograms, and ancestor-state reconstruction, were used to evaluate phylogenetic inertia in these traits. Results were highly dependent on the method applied. Autoregression and phylogenetic eigenvector regression (PVR) methods found more inertia in morphological traits. In contrast, phylogenetic correlograms and ancestor-state reconstruction suggest that morphological characters exhibit less phylogenetic inertia than demographic ones. The differences between results are discussed and methods are compared in an effort to understand phylogenetic inertia more thoroughly.

Asteraceae↗

Influence of obesity on the appearance of proteinuria and renal insufficiency after unilateral nephrectomy.

BACKGROUND: Some patients develop proteinuria and progressive renal failure after unilateral nephrectomy, although the majority of patients maintain normal renal function. Reasons to explain this different evolution are not known. METHODS: A cross-sectional study was performed in 73 patients who had undergone unilateral nephrectomy 13.6 +/- 8.6 years before. Patients with morphologic abnormalities in the remaining kidney, systemic disorders, or abnormal renal function at the time of nephrectomy were excluded. All of the 73 included patients showed normal renal function and negative proteinuria at nephrectomy. The patient's medical records were reviewed, and clinical and analytical data throughout follow-up were obtained. RESULTS: Fifty-three out of the 73 patients (group I) showed a normal renal function and negative proteinuria at the cross-sectional study. The remaining 20 patients (group II) showed proteinuria (3.4 +/- 3.1 g/day). The time elapsed between nephrectomy and proteinuria appearance was 10.1 +/- 6.1 years. Thirteen patients of group II had developed renal insufficiency (serum creatinine at the cross-sectional study of 3.9 + 3.2 mg/dL) in addition to proteinuria. The time elapsed between proteinuria appearance and the onset of renal insufficiency was 4.1 +/- 4.3 years. Renal insufficiency showed a slowly progressive course in most of these patients. There were no significant differences between group I and group II patients in age, gender, renal function, or blood pressure at the time of nephrectomy. In contrast, group II patients showed a body mass index (BMI) that was significantly higher than group I at nephrectomy (31.6 +/- 5.6 vs. 24.3 +/- 3.7 kg/m(2), P < 0.001), at cross-sectional study (33.3 +/- 6.6 vs. 25.1 +/- 3.5 kg/m(2), P < 0.001), and throughout follow-up. Among the 14 obese (BMI > 30 kg/m(2)) patients at the time of nephrectomy, 13 (92%) developed proteinuria/renal insufficiency. In contrast, among the 59 patients with BMI < 30 kg/m(2), only 7 (12%) developed these complications (P < 0.001). Kaplan-Meier estimated probability of negative proteinuria and normal renal function 10 years after nephrectomy was 40 and 70%, respectively, in obese patients at nephrectomy. At 20 years after nephrectomy, these percentages were 8 and 35%, respectively. In contrast, in nonobese patients, the probability of negative proteinuria and normal renal function was 93 and 98%, respectively, at 10 years (P < 0.001) and 77 and 91%, respectively, at 20 years (P < 0.001). Multiple logistic regression analysis showed that the risk of developing renal disease was only statistically correlated with BMI at the time of unilateral nephrectomy (odds ratio 1.34, 1.03 to 1.76 CI). CONCLUSIONS: Obese patients are at risk for developing proteinuria and chronic renal failure after unilateral nephrectomy. Regular and long-term follow-up are recommended in these patients.

Acute Kidney Injury↗