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V Valencia

Publications and source records attributed to V Valencia.

10 recordsLinked to original sources
PubMed2006

Maximum likelihood mixture estimation to determine metal background values in estuarine and coastal sediments within the European Water Framework Directive.

Some of the recently derived European Directives, such as the Water Framework and Marine Strategy, have, as ultimate aims, to achieve concentrations of hazardous substances in the marine environment near background values. Hence, the determination of natural background levels, in marine sediments, is highly relevant. The present study proposes the use of the maximum likelihood mixture estimation (MLME) to determine regional background levels and upper threshold of metal concentration, with the Basque Country as a case study (with a data set of 575 samples, from estuarine and littoral areas, including both intertidal and subtidal sediments). The heuristic procedure is applied with unimodal data distributions (Cd, Cr, Fe and Ni) and the mixture density estimations, based upon maximum likelihood, are carried out with polypopulational data distributions (As, Cu, Mn, Hg, Pb and Zn). The upper limits of the distribution are proposed, as the limits between 'High Status' and 'Good Status' (according to the Water Framework Directive terminology). The regional upper limits were 0.45 microg g(-1) for Cd, 71 microg g(-1) for Cr, 53,542 microg g(-1) for Fe, 57 microg g(-1) for Ni, 24 microg g(-1) for As, 64 microg g(-1) for Cu, 447 microg g(-1) for Mn, 0.27 microg g(-1) for Hg, 66 microg g(-1) for Pb, and 248 microg g(-1) for Zn. The results from this study can assist further in the determination of sediment reference conditions, to assess chemical status, within the above-mentioned directives; likewise, it will be studied as a useful methodology in determining regional metal backgrounds in other European countries.

Arsenic↗
PubMed2005

Assessing reference conditions and physico-chemical status according to the European Water Framework Directive: a case-study from the Basque Country (Northern Spain).

The European Water Framework Directive requires the development of new and accurate methodologies, addressing the assessment of the physico-chemical status of transitional and coastal waters; these are considered by the Directive as the supporting elements for the final evaluation of the Ecological Quality Status. This contribution develops new approaches in the determination of the physico-chemical status, solving some problems detected in previous contributions, i.e.: (a) fitting the classification of water bodies and typologies, by means of the stretching of the typologies, according to the natural salinity gradient of types; (b) defining reference conditions, based upon the new approach to typologies, (c) proposing accurate multivariate methodologies, in determining the physico-chemical status of the transitional and coastal waters, based upon the defined typologies and references; and (d) discussion of the results obtained by reference to methodological aspects and water quality evolution in the Basque Country, Spain (as a case-study), during the last decade.

Cluster Analysis↗
PubMed1994

[Cysts of second branchial cleft: review of 32 operated cases].

The aim of this work was to analyze retrospectively the clinical features of 32 patients aged 23.9 years (21 female) with the histological diagnosis of second branchial cleft cyst. In 28 patients, the cyst was localized below the mandibular angle. The presenting symptom was a cervical tumor in 30 patients and pain in eight. Fourteen aspiration punctures was performed obtaining 8 purulent and 6 straw colored aspirates. The preoperative diagnosis was correctly made in only 19 patients; the principal confounding diagnosis was tuberculous adenitis. All patients were operated performing a complete cystectomy in 30 and partial cystectomy in two. Three patients had a surgical wound infection and the cysts recurred 5 months and 4 years after operation in the two patients subjected to partial cystectomy. The histological study revealed squamous epithelial with underlying lymphoid tissue. It is concluded that aspiration puncture is useful for the correct diagnosis and that the cyst must be completely eradicated to avoid recurrences.

Adolescent↗
PubMed1991

[Needle aspiration cytology in euthyroid uninodular goiter].

Fine needle aspiration cytology (FNAC) has been shown to be second only to surgical biopsy for demonstration of malignancy in thyroid nodules. A prospective study of FNAC for euthyroid uninodular goiter (EUG) was conducted between January 1987 and June 1990, totaling 87 patients of which 61 were submitted to surgical biopsy. FNAC in the latter were interpreted as benign in 41 cases, suspected malignancy in 8, and definitely malignant in 7. The remaining 5 smears were considered technically inadequate for diagnosis. In 39 of the 41 patients with a benign (negative) cytology result, the histopathological diagnosis confirmed the absence of a neoplastic process (2 false negatives). In 12 of the 15 patients with a suspected malignant (positive) cytology result, a subsequent histopathological report confirmed a neoplastic process (3 false positives). Thus FNAC had a sensitivity of 86% and a specificity of 93%. We conclude that FNAC is a valuable tool for the diagnosis of erythroid goiter and could help reduce significantly the number of patients who need to be surgically intervened.

Adolescent↗
PubMed1991

[Shortened preoperative preparation in diffuse hyperthyroid goiter: experience in 34 patients].

Conventional preparation of goitrous hyperthyroid patients using lugol and propranolol may take 2 weeks. This period may be shortened using sodium iopodate and dexamethasone. We used 500 mg of sodium iopodate and 1 mg dexamethasone for 4 days in 34 hyperthyroid patients. Surgical indication derived from failure to medical treatment (68%), large goiter (27%) or adverse reaction to PTU (6%). Clinical euthyroidism was achieved after 4 days in all patients. T3 levels decreased from 482 +/- 26.2 to 137.6 +/- 3.7 ng/dl and T4 from 20.6 +/- 1.04 to 15.2 +/- 0.5 micrograms/dl (p < 0.005). Surgery was uneventful in 33 patients, one subject developed supraventricular tachycardia responsive to verapamil. Electron microscopy of the removed thyroid tissue revealed marked decrease of superficial villi and large phagosomes. Thus, sodium iopodate and dexamethasone are effective and safe for preoperative preparation of hyperthyroid patients.

Adolescent↗
PubMed1990

[Lymphomas of the parotid region].

Parotid gland lymphomas are very uncommon. Two patients with this condition were treated in the last decade. Surgery should be used only for diagnosis and becomes unnecessary when adenopathy is present, since a lymph node biopsy will establish the diagnosis.

Adolescent↗
PubMedDate not supplied

[Peutz-Jeghers syndrome. Apropos a familial case at Hospital Arzobispo Loayza].

The Peutz-Jeghers syndrome is a rare dominant autosomic, entity characterized by hyperpigmented lesions on the lips, hands and feet; with presence of gastrointestinal polyps producing acute or chronic anemia, intestinal obstruction, and/or abdominal pain. This polyps histologically are hamartomas; recent studies indicate a real risk for transformations in the malignant neoplasia. The high and low endoscopies and the intraoperative enteroscopy with polypectomy are the election treatment, improving prognosis quality on these patients. We describe a familiar case of a female patient 24 years old showing a repeated picture of intestinal subocclusion; her brother presented a similar clinical picture, and her mother presented the same syndrome, dying of carcinoma in the colon; also her child, at one and a half year old presented hyperpigmented lesions on the lips.

Adult↗