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Biomedical subjects

A Sepúlveda

Publications and source records attributed to A Sepúlveda.

At least 19 recordsLinked to original sources
PubMed2004

Use of 137Cs measurements to estimate changes in soil erosion rates associated with changes in soil management practices on cultivated land.

Intensification of agricultural production in south-central Chile since the 1970s has caused problems of increased soil erosion and associated soil degradation. These problems have prompted a shift from conventional tillage to no-till management practices. Faced with the need to establish the impact of this shift in soil management on rates of soil loss, the use of caesium-137 (137Cs) measurements has been explored. A novel procedure for using measurements of the 137Cs depth distribution to estimate rates of soil loss at a sampling point under the original conventional tillage and after the shift to no-till management has been developed. This procedure has been successfully applied to a study site at Buenos Aires farm near Carahue in the 9th region of Chile. The results obtained indicate that the shift from conventional tillage to no-till management has caused net rates of soil loss to decrease to about 40% of those existing under conventional tillage. This assessment of the impact of introducing no-till management at the study site must, however, be seen as provisional, since only a limited number of sampling points were used. A simplified procedure aimed at documenting the reduction in erosion rates at additional sampling points, based solely on measurements of the 137Cs inventory of bulk cores and the 137Cs activity in the upper part of the soil has been developed and successfully tested at the study site. Previous application of 137Cs measurements to estimate erosion rates has been limited to estimation of medium-term erosion rates during the period extending from the beginning of fallout receipt to the time of sampling. The procedures described in this paper, which permits estimation of the change in erosion rates associated with a shift in land management practices, must be seen as representing a novel application of 137Cs measurements in soil erosion investigations.

Agriculture↗
PubMed2002

[Study of the susceptibility of black yeasts of the Exophiala genus to antifungals using the Sensititre System].

Black yeasts belong to a group of dematiaceous fungi which are difficult to classify and identify. One of the genera that cause human infection, mainly phaeohyphomycosis, is Exophiala, which includes the species E. berger, E. castellanii, E. dermatitidis, E. jeanselmei, E. lecanii-corni, E. moniliae, E. pisciphila, E. salmonis and E. spinifera. We carried out a susceptibility study of five of these species (E. castellanii, E.dermatitidis, E, jeanselmei, E. lecanii-corni and E. moniliae), isolated from cutaneous exudates, to the usual antimycotic agents. Strains were cultured on Sabouraud agar and potato-dextrose agar. Species identification was made by conidiogenous microscopic observation and the following characteristics: maximum growth temperature, tolerance to cicloheximide and carbohydrate assimilation. Susceptibility to antimycotic agents (amphotericin B, fluconazole, itraconazole, ketoconazole and 5-fluorocytosine) was determined by the Sensititre YeastOne (Aamar Blue) commercial method. Amphotericin B activity was good for the five tested species, although the MIC for E. jeanselmei was high (1 mg/l. MICs for fluconazole were high for all the species, but only E. moniliae and E. lecanii-corni c be considered resistant. Activity of itraconazole, ketoconazole and 5-fluorocytosine was good.

Antifungal Agents↗
PubMed2001

Hantavirus pulmonary syndrome due to Andes virus in Temuco, Chile: clinical experience with 16 adults.

STUDY OBJECTIVES: To describe the clinical features and laboratory abnormalities of 16 adults with confirmed Hantavirus pulmonary syndrome (HPS) due to Andes virus in Temuco, Chile. DESIGN: A retrospective chart review abstracting clinical, radiologic, laboratory, and epidemiologic data. SETTING: ICU of the university teaching hospital in Temuco, Chile. PATIENTS: Sixteen patients with HPS treated between 1997 and 1999. RESULTS: Patients were aged from 19 to 45 years, 82% were men, and 88% were farm or timber workers with occupational acquisition of HPS. After an incubation period ranging from 5 to 25 days, a prodromal influenza-like phase frequently was accompanied by abdominal symptoms. From 1 to 7 days later, respiratory insufficiency and hemodynamic instability suddenly appeared. In 81%, hemorrhage was evident; in 63%, moderate-to-severe bleeding occurred. The most prominent laboratory abnormalities were hemoconcentration, leukocytosis, thrombocytopenia, altered partial thromboplastin time (PTT), creatine kinase, transaminases, and hyponatremia. Creatinine elevation was common, with clinical importance in two patients. All patients had severe hypoxemia and pulmonary edema. Fifteen patients received supportive treatment, and 5 patients were treated with corticosteroids. The mortality rate was 43.8%. CONCLUSIONS: Bad prognostic factors appeared to be severe hypotension, lower PaO(2)/fraction of inspired oxygen values, prolonged PTT, hemorrhage, greater volume load, and profuse bronchorrhea. The effects of treatment with corticosteroids could not be determined. Hemorrhage and renal involvement were common in our patients, features not often described in the North American literature of Sin Nombre virus HPS.

Adult↗
PubMed2000

[Thyroid cancer. Report of 85 cases].

BACKGROUND: Thyroid cancer is the most frequent endocrine cancer with important implications in terms of diagnosis and treatment. AIM: To report a population of patients with thyroid cancer diagnosed by pathological studies of the surgical piece. PATIENTS AND METHODS: Eighty five patients (68 female) with the definitive diagnosis of thyroid cancer were studied. Clinical, imaginological, cytological and pathological findings were analyzed. RESULTS: The age range of patients was 10 to 77 years old. Sixty nine patients had ultrasonographic studies which showed a solid nodule in 84%, mixed solid-cystic area in 14.5% and a purely cystic nodule in 1.5% of the cases. Nineteen patients had non specific calcifications. Fine needle aspiration cytology was negative for malignancy in eight patients (false negative rate of 9.9%). The average size of the nodules was of 2.8 +/- 1.6 cm). Six nodules measured less than one cm (microcarcinoma). In the initial surgical procedure, 13 patients had lymph node metastases, 2 of them had a primary tumor of 1 cm and 5 patients had Graves's Disease. Frozen biopsies during operation had 9 false negative results for cancer (10.6%). Pathology showed 64 cases of papillary cancer (75%), 14 of follicular (16.5%), two were Hurthle cell cancer (2.4%), three were medullary (3.5%), and two anaplastic (2.4%). CONCLUSIONS: In our experience, thyroid cancer is more common in women, solid lesions predominate in the ultrasonography and calcifications are frequently found. The tumor size is variable and the most frequent pathological type corresponds to differentiated cancers. Using the definitive pathological study as the standard, the diagnostic sensitivity of fine needle cytology was 90.1%, and of frozen section 89.4%.

Adolescent↗
PubMed1999

Derangement of Kupffer cell functioning and hepatotoxicity in hyperthyroid rats subjected to acute iron overload.

Liver oxidative stress, Kupffer cell functioning, and cell injury were studied in control rats and in animals subjected to L-3,3',5-tri-iodothyronine (T3) and/or acute iron overload. Thyroid calorigenesis with increased rates of hepatic O2 uptake was not altered by iron treatment, whereas iron enhanced serum and liver iron levels independently of T3. Liver thiobarbituric acid reactants formation increased by 5.8-, 5.7-, or 11.0-fold by T3, iron, or their combined treatment, respectively. Iron enhanced the content of protein carbonyls independently of T3 administration, whereas glutathione levels decreased in T3- and iron-treated rats (54%) and in T3Fe-treated animals (71%). Colloidal carbon infusion into perfused livers elicited a 109% and 68% increase in O2 uptake in T3 and iron-treated rats over controls. This parameter was decreased (78%) by the joint T3Fe administration and abolished by gadolinium chloride (GdCl3) pretreatment in all experimental groups. Hyperthyroidism and iron overload did not modify the sinusoidal efflux of lactate dehydrogenase, whereas T3Fe-treated rats exhibited a 35-fold increase over control values, with a 54% reduction by GdCl3 pretreatment. Histological studies showed a slight increase in the number or size of Kupffer cells in hyperthyroid rats or in iron overloaded animals, respectively. Kupffer cell hypertrophy and hyperplasia with presence of inflammatory cells and increased hepatic myeloperoxidase activity were found in T3Fe-treated rats. It is concluded that hyperthyroidism increases the susceptibility of the liver to the toxic effects of iron, which seems to be related to the development of a severe oxidative stress status in the tissue, thus contributing to the concomitant liver injury and impairment of Kupffer cell phagocytosis and particle-induced respiratory burst activity.

Animals↗
PubMed1998

Necrotizing fasciitis of the face and neck.

Necrotizing fasciitis is a rare infection in the surgical and infectious medical services, but when it is present, in most cases, the affected areas are the lower extremities and the abdominal and thoracic walls, and more frequently in perineum and genital areas, which is commonly known as Fournier's gangrene. This type of infection is extremely rare in the face and neck, because the great vascularity in these regions makes the tissues rarely susceptible to ischemia and infection, even when large flaps are lifted in reconstructive and aesthetic procedures. We present a case of necrotizing fasciitis in face and neck, with emphasis on the medical and surgical treatment that should be based on antibiotic therapy of broad spectrum; secondary reconstructive procedures should be planned.

Aged↗
PubMed1996

[Bacterial urovirulence factors and their association with functional and anatomical abnormalities and recurrence of urinary tract infections in children].

BACKGROUND: Urinary tract infections in children are associated with functional and anatomical abnormalities of the urinary tract, they tend to recur and can cause permanent kidney damage. AIM: To study in children with urinary tract infections, microbiological factors associated to recurrence, functional and anatomical abnormalities of the urinary tract. PATIENTS AND METHODS: A prospective sample of children was incorporated into a follow-up protocol after their first episode of bacteriologically-demonstrated urinary tract infection. In all patients an abdominal ultrasound examination and a mictional urethrocystography were done and the presence of fimbriae was studied in isolated strains of Escherichia coli. RESULTS: Two hundred fifteen cases bad an adequate adherence to the study protocol, 190 caused by E coli. Fimbriated E coli strains were isolated with greater frequency from children with pyelonephritis than from those with a low urinary tract infection (50 and 28% respectively). The absence of fimbriae in E coli strains was associated with a higher risk of recurrent infections (odds ratio = 3, confidence intervals = 2-9.2) and an abnormal urethrocystography (odds ratio = 3, confidence intervals = 1.1-10.2). CONCLUSIONS: These data are consistent with foreign reports and support the need to study adhesins in E coli strains isolated from children with urinary tract infections.

Bacterial Infections↗
PubMed1995

[Thyroid nodule in Basedow-Graves disease and thyroid cancer: experience in 6 patients].

Traditionally, Basedow-Graves disease was considered a protection against thyroid cancer. However, recent reports suggest that cancer occurs with a higher frequency than expected and is more aggressive in this disease. We report six patients with hyperthyroidism due to a Basedow Graves disease that presented a palpable thyroid nodule, which was cold in the scintiscan and solid in the ultrasound examination. Fine needle cytology disclosed cancer in five cases (two with cytological features of greater aggressiveness) and a nodular hyperplasia in one. The diagnosis was confirmed in the surgical piece in all patients. We conclude that Basedow-Graves disease and thyroid cancer, which can have an increased aggressiveness, may coexist.

Adolescent↗
PubMed1994

[The clinical estimate of adiposity is not a good predictor of insulin tissue sensitivity measured with a minimal model analysis].

Fifteen male volunteers, aged 30 to 40 years old, were classified according to body mass index (BMI) as lean (n = 5, BMI less than 20 kg/m2), normal (n = 5, BMI 20-25) or obese (n = 5, BMI over 30). Glucose intolerance was ruled out by a normal oral glucose tolerance test and insulin sensitivity (SI) and glucose effectiveness (SG) were estimated by a minimal model analysis of a frequently sampled intravenous glucose tolerance test modified by an intravenous insulin injection at minute 20. The MINMOD program was fed with 29 or 12 values (reduced sampling schedule). Despite a significant inverse correlation between BMI and SI (r = -0.533 p < 0.05), the latter parameter overlapped among groups and the correlation was lost when obese individuals were not considered. Waist/hip ratio correlated modestly with SI (r = -0.52 p < 0.05). SG did not correlate with BMI. Using the reduced sampling schedule. SI values had a correlation coefficient of 0.78 with those calculated using the usual sampling schedule, although they were 82% lower. We conclude that only a BMI of over 30 accurately predicts a low SI, and that waist/hip ratio does not have a better predictive power.

Adult↗
PubMed1988

Common bile duct pressure in patients with common bile duct stones with or without acute suppurative cholangitis.

Resting common bile duct pressure was measured in three groups of patients: group 1, 53 patients with gallstones but without common duct stones; group 2, 35 patients with common bile duct stones unaccompanied by cholangitis; and group 3, 36 patients with common duct stones and acute suppurative cholangitis. A significantly higher pressure in the common bile duct was documented in patients with cholangitis when compared with the other two groups. Twenty-four patients with cholangitis had common duct pressure values above 20 cm H2O, the maximal values of normal. Additionally, patients with cholangitis with pressure values over 30 cm H2O (nine patients) showed absence of green bile in the extrahepatic biliary tract, suggesting cessation of bile excretion into biliary duct. In all these cases, an impacted stone at the distal end of the common bile duct was documented.

Acute Disease↗
PubMed1986

A simple algorithm for assisting medical diagnosis.

This is a description of an algorithm to assist in the selection of the most probable diagnosis of a given patient. This algorithm is based on the comparison of a scaled column vector of the symptoms displayed by the patient, and of each column of symptoms appearing in a disease matrix. Moreover, the same algorithm gives the degree of similarity of the diseases compared by the differential diagnosis, as well as the hierarchic order of the symptoms that characterise any disease.

Algorithms↗
PubMed1985

Conservation of the secondary structure of protein during evolution and the role of the genetic code.

In this communication we demonstrate, in a group of modern proteins, following an algorithm described by Argyle (1980), that the ordination of the amino acids in terms of the most frequent substitutions agrees with the conservation of the alpha-helix, beta-sheet, and beta-turn formation tendencies during evolution. The same correspondence has been demonstrated for the conservation of the physico-chemical properties in the amino acid substitutions. Both parameters are similar in showing higher correlation with the most frequent amino acid substitutions than with the feasibility of changes at the level of the respective codons. Some kind of restrictions for the expression of the genomic changes, due to the conservation of the secondary structure of proteins and/or the physicochemical properties of the substituted amino acids, could account for the differences found between the distribution of the amino acid substitutions and the most probable codon changes.

Amino Acids↗