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Biomedical subjects

A Arias

Publications and source records attributed to A Arias.

At least 55 records · Page 3Linked to original sources

Essential oils and antimicrobial activity of two varieties of Cedronella canariensis (L.) W. et B.

The qualitative and quantitative determination of the essential oils of the aerial part of two varieties of Cedronella canariensis (L.) W. et B., namely, C. canariensis var. canariensis and C. canariensis var. anisata have been performed, together with the study of the antimicrobial activity of both oils. The noteworthy inhibition exhibited against Bordetella bronchiseptica and Cryptococcus albidus may justify the popular use of the these plants in the treatment of certain diseases of the respiratory tract.

Bacteria↗

Expression of neuronal markers in the so-called ENU-induced schwannomas.

The present data show that the so-called ENU-induced malignant schwannomas express neuronal markers. This finding supports the hypothesis that a population of tumor cells in these neoplasms are neuroblastic in nature, and suggests the classification of ENU-induced schwannomas as primitive neuroectodermal tumors.

Animals↗

Myocardial hypertrophy, cardiac beta-adrenoceptors and adenylate cyclase activity during sinoaortic denervation in dogs.

1. The long-term effects of sinoaortic denervation on the development of left ventricular hypertrophy (assessed by the measurement of the ratio (R): heart weight/total body weight and LVT: left ventricular thickness), myocardial beta-adrenergic receptivity (measured by [125I]-cyanopindolol binding and adenylate cyclase activity) and plasma catecholamine levels (measured by h.p.l.c.) were investigated in three groups of dogs: normotensive controls (group 1), dogs made hypertensive by sinoaortic denervation and evaluated 1 (group 2) and 18 months (group 3) later. 2. Noradrenaline (NA) and adrenaline (A) plasma levels were 461 +/- 54 and 85 +/- 45 pg ml-1 in controls, 861 +/- 185 and 191 +/- 23 pg ml-1 in group 2 (P less than 0.05). They were normal in group 3 (426 +/- 132 and 110 +/- 16 pg ml-1). 3. R and LVT values were significantly (P less than 0.05) higher in sinoaortic denervated dogs (R = 7.7 +/- 0.1 and 7.8 +/- 0.2; LVT = 13.6 +/- 1.3 and 14.2 +/- 0.9 mm in groups 2 and 3 respectively) than in normotensive dogs (group 1: R = 6.7 +/- 0.1, LVT = 9.3 +/- 0.8 mm). 4. In group 1, the total number of beta-adrenoceptors (Bmax) was 37 +/- 11 and 29 +/- 6 fmol mg-1 protein in the left ventricle (LV) and right auricle (RA) respectively. In group 2, Bmax was significantly lower (10 +/- 3 in LV and 13 +/- 2 fmol mg-1 protein in RA, P less than 0.05) than in group 1. There was no difference between group 1 and group 3 (37 +/- 3 fmol mg-1 prot in LV and 31 +/- 3 fmol mg-1 protein in RA). 5. The percentage of beta 1-adrenoceptors was 82 +/- 4 in LV and 75 +/- 5 in RA in group 1. It was significantly lower (P less than 0.05) in groups 2 (LV: 33 +/- 6 and RA: 33 +/- 5) and 3 (LV: 59 +/- 3 and RA: 55 +/- 4). 6. Basal values of adenylate cyclase activity in LV significantly decreased after sinoaortic denervation.7. These data show that sinoaortic denervation is associated with left ventricular hypertrophy which appears early (1 month) and persists until 18 months despite the normalization of plasma catecholamine levels. The total number of myocardial beta-adrenoceptors is closely related to catecholamine levels but a selective decrease in beta 1-adrenoceptors is observed during cardiac hypertrophy. The fall in basal adenylate cyclase activity suggests that cardiac hypertrophy is associated with an impairment of transmembrane signalling.

Adenylyl Cyclases↗

Deep venous thrombosis and the risk of pulmonary embolism. A systematic study.

The influence of several diseases and clinical conditions on the presence of pulmonary embolism (PE) in a large series of patients with deep venous thrombosis (DVT) in the lower extremities was analyzed prospectively. Lung scan findings from a series of 434 consecutive patients with DVT (with and without symptoms of PE) were studied and then correlated to five clinical variables: age, sex, elapsed time since clinical symptoms had appeared in the leg to diagnosis, degree of proximity of venous thrombus, and the presence or not of several risk factors that could have predisposed to thrombus development. According to scintigraphic findings, 164 patients were considered to have PE (asymptomatic in 76 of them), while 200 patients were classified as having only DVT. Lung scan was considered to be indeterminate for PE in 70 patients, and they were not included in the study. No differences were found in terms of age, sex, interval of time elapsed since onset of symptoms to diagnosis, or in the degree of proximity of the thrombus. However, several differences between groups were found when comparing the presence or absence of several predisposing factors for thrombosis: DVT developing in immobilized patients was associated with a significantly lower incidence of PE as compared with nonimmobilized patients (p = 0.005). Conversely, patients with a history of venous thromboembolism (VTE) had a significantly higher rate of embolism (31/51 vs 133/313; p = 0.01). On logistic regression analysis, a history of VTE showed a statistically significant association with more than a twofold higher risk of having PE for patients with such an antecedent. Our findings suggest that different pathophysiologic pathways could perhaps explain differences in embolic potential.

Causality↗

[Beta adrenergic receptors and experimental left ventricular hypertrophy].

The effects of sinoaortic denervation (SAD) on the development of left ventricular hypertrophy (R: heart weight/total body weight; LVT : left ventricular thickness), myocardial beta-adrenergic receptivity ([125I]CYP binding; adenylate cyclase activity) and plasma catecholamine levels (HPLC) were investigated in both normotensive (group 1) and hypertensive dogs evaluated (group 2) 1 and 18 months (group 3) after SAD. Noradrenaline (NA) and adrenaline (A) plasma levels were 461 +/- 54 and 85 +/- 45 pg/ml in controls, 861 +/- 185 and 191 +/- 23 pg/ml in group 2 (P < 0.05) and were normal in group 3 (426 +/- 132 and 110 +/- 16 pg/ml). R and LVT values were higher (p < 0.05) in SAD dogs (R = 7.7 +/- 0.1 and 7.8 +/- 0.2; LVT = 13.6 +/- 1.3 and 14.2 +/- 0.9 mm in groups 2 and 3 respectively) than in group 1 (R = 6.7 +/- 0.1, LVT = 9.3 +/- 0.8 mm). In group 1, the total number of beta-adrenoceptors (beta-AR) was 37 +/- 11 and 29 +/- 6 fmol/mg prot in left ventricule (LV) and right auricle (RA) respectively. Bmax was significantly lower in group 2 (LV: 10 +/- 3; RA: 13 +/- 2 fmol/mg prot, p < 0.05) than in group 1 but was normal in group 3 (LV: 37 +/- 3 and RA: 31 +/- 3 fmol/mg prot).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenylyl Cyclases↗

Synaptophysin expression in "ependymal tumors" induced by ethyl-nitrosourea in rats.

Synaptophysin expression was studied in seven "ependymomas" induced by transplacental administration of ethyl-nitrosourea in rats. In all the cases, strong positivity for synaptophysin was found on tumor cells. This finding supports previous studies suggesting that ENU-induced brain tumors considered to be ependymal neoplasms, are, in fact, primitive neuroectodermal tumors.

Animals↗

Influence of recombinant interleukin-2 and tumor necrosis factor-alpha on the development of ethyl nitrosourea-induced brain tumors.

Using the experimental model of brain tumors induced by ethyl-nitrosourea (ENU), human recombinant interleukin-2 (rIL-2) and tumor necrosis factor-alpha (TNF-alpha) were administered to Wistar rats in early stages of carcinogenesis. The results obtained suggest that IL-2 does not influence the development of nervous system tumors. In contrast, TNF-alpha was capable of modulating the development of ENU-induced tumors, producing a reduction in the number of schwannomas and a delay in the appearance of intraparenchymatous brain tumors.

Animals↗

Expression of neuronal and glial markers in so-called oligodendroglial tumors induced by transplacental administration of ethyl-nitrosourea in the rat.

A series of 18 tumors with histological features of oligodendrogliomas, induced in the rat by means of transplacental ethyl-nitrosourea administration were studied for immunohistochemical demonstration of neuronal (synaptophysin and neurofilament protein) and glial (gliofibrillar acidic protein and vimentin) markers. Most of the tumors showed cells with strong positivity to synaptophysin and to a lesser degree, to neurofilament protein, suggesting the neuronal character of these neoplasms. In 10 tumors, cells with strong positivity to vimentin were found, and in three cases, tumoral cells expressed gliofibrillar acidic protein. The observation that ENU-induced oligodendroglial tumors express neuronal and, to a minor degree, glial markers, suggests their interpretation as primitive neuroectodermal tumors with clear neuronal differentiation.

Animals↗

[Concentrations of serum cholesterol in Spanish children: results of a study on the isle of Menorca].

BACKGROUND: The little knowledge about the distribution of total cholesterol (TC) in childhood and adolescence in Spain, makes the planification of preventive measures for cardiovascular diseases difficult. The aim of this study is to determinate these values in the island of Menorca. METHODS: A sample of 1,062 boys and girls 6 to 18 years of age was studied. Blood samples were obtained by venipuncture and were analyzed by the enzymatic techniques of cholesterol-esterase, cholesterol-oxidase, and peroxidase. RESULTS: Boys showed lower mean TC values than girls in almost all age groups. In both sexes, a descending phase was observed in the TC by age curve at the beginning of the adolescence. TC values above 5.17 mmol/l (200 mg/dl) were recorded for 7% of participants, being this proportion lower than the value found in the Spanish study of Fuenlabrada (13%). CONCLUSIONS: Results obtained are compared with other national and international studies. The values of this study rank an intermediate position between the highest mean TC values registered in Norway and the lowest registered in Israel.

Adolescent↗

Pharmacological evidence of alpha 1- and alpha 2-adrenergic supersensitivity in orthostatic hypotension due to spinal cord injury: a case report.

Sympathetic efferent pathways and alpha-adrenergic receptivity were investigated in one patient with spinal cord transection (D1 level) and orthostatic hypotension. The lack of increase in catecholamine plasma levels during orthostasis and the paradoxical pressor effect of clonidine (2 micrograms/kg orally) suggested complete interruption of efferent sympathetic pathways. The pressor response to exogenous noradrenaline was significantly higher in the patient than in 6 normal controls (0.09 vs 0.72 micrograms.kg-1), indicating supersensitivity of vascular alpha-adrenoceptors. The platelet alpha 2-adrenergic receptor number, measured with [3H]yohimbine, was 507 in the patient vs 178 fmol.mg-1 protein in controls. The increase in systolic blood pressure induced by 10 mg midodrine, a specific alpha 1-agonist, was significantly higher in the patient (delta = 56 mm Hg) than in controls (delta = 15 mm Hg). The results indicate that in the patient there was alpha-adrenergic supersensitivity both of alpha 1- and alpha 2-adrenoceptors. This led to successfully oral treatment of the orthostatic hypotension with clonidine 150 micrograms bd and midodrine 10 mg bd.

Blood Pressure↗

Clinico-morphological correlation in syringomyelia: a statistical study assisted by computer measurement of magnetic resonance images.

A computer-assisted measurement of synrinxes was performed on MR images in a series of 26 patients with syringomyelia-Chiari complex. Syrinx data such as length, surface area, contour, and greater diameter were statistically correlated to each other and with the main clinical symptomatology of the patients. In general, a direct relationship between the various measurements of the syrinxes exists. Nevertheless, although a slight relationship could be established between the presence of muscular atrophy and a greater length and contour of the syrinxes, the present study suggests that the evaluation of syrinx dimensions cannot be brought into relation with the nature or distribution of clinical symptomatology. Because a reduction in the syrinx is generally the aim of surgery, this conclusion should be born in mind when a surgical treatment is offered to syringomyelic patients.

Adult↗

Chromaffin allografts into arachnoid of spinal cord reduce basal pain responses in rats.

In this present study, behavioral responses to a subcutaneous formalin test for pain are evaluated in rats that previously received an allograft of adrenal chromaffin tissue into arachnoid of the dorsal spinal cord and in control animals. In the group of rats with grafts, a significant basal analgesia, reversed by the opioid antagonist naloxone, is found. These findings suggest that the grafts secrete some substance that reduces the response to painful stimulation and whose action is blocked by naloxone.

Adrenal Medulla↗

Role of granulocytes in the development of venous thrombosis in patients with hip fractures.

In a previously reported study we compared the use of a low-molecular-weight heparin (LMWH) and conventional heparin in the thromboprophylaxis of patients with hip fracture. In an attempt to establish additional factors which could aid in predicting the development of deep-venous thrombosis (DVT), we retrospectively studied several clinical and laboratory variables and found that granulocyte count on admission was higher in patients without subsequent postoperative DVT. Forty additional patients were included in a further prospective study in order to validate our previous findings. 38% of patients who developed DVT had a granulocyte count lower than 9,500/microliters, whereas only 18% of those patients with DVT had a count higher than 9,500/microliters. These figures imply a positive predictive value of 38% and a negative predictive value of 82%. We suggest that granulocytes could play a role in the development of DVT and preoperative granulocyte count may be used to detect a high-risk population for DVT after a hip fracture.

Adult↗

Acute gastroduodenal lesions in patients with venous thromboembolism. Identification of patients at risk.

The prime complication of heparin therapy is bleeding, and the gastrointestinal tract is the most common site of bleeding in patients treated with heparin. We recently reported that gastroduodenal lesions are common in patients admitted because of acute venous thromboembolism, and now we present our experience in a larger series of patients. The aims of the study were to try to validate our previous findings and to identify clinical factors that could increase the likelihood of having an acute, potential bleeding lesion in the gastroduodenal tract. Upper gastrointestinal endoscopy was performed on admission in 155 consecutive patients with acute venous thromboembolism (118 with deep vein thrombosis, 37 with pulmonary embolism). Acute lesions (both peptic ulcers and diffuse erosions) were found in 19 of 118 patients (16 percent) with venous thrombosis, and in 14 of 37 patients (38 percent) with pulmonary embolism (p = 0.005). When only patients with pulmonary embolism were considered, lesions were more commonly found in men, and in patients with severe hypoxemia on admission. When considered overall, only the timing of endoscopy was statistically significant; acute lesions were more commonly found when endoscopy was performed early after admission. No significant differences were found in terms of age, sex, smoking habits, alcohol intake, concomitant drug ingestion, comorbid diseases, or previous history of ulcer. The very high incidence of upper GI tract lesions in these patients will have long-term diagnostic/therapeutic implications which cannot be ignored. Who should receive prophylactic H2 blockers and for how long remains to be determined.

Acute Disease↗

Platelet count and venous thromboembolism. A useful test for suspected pulmonary embolism.

We have previously reported that patients with deep vein thrombosis (DVT) and scintigraphic evidence of pulmonary embolism (PE) had a fall in platelet count, as compared with their levels before thrombosis had developed. Otherwise, no changes were found in DVT patients without embolism. We recently conducted a prospective study with a larger series of patients and studied platelet count behavior in 189 consecutive patients with acute venous thromboembolism (VTE) in whom a baseline blood cell count was available (obtained before thromboembolism developed). We found no significant differences in baseline platelet counts between groups. However, at the time of VTE diagnosis the analysis of variance demonstrated that mean platelet count was significantly higher in patients without embolism as compared with PE patients (p less than 0.001). On the other hand, no differences were found between patients with silent PE and those with clinically obvious PE. When patients with postoperative VTE and those with nonpostoperative VTE were analyzed separately, mean platelet count increased only in postoperative DVT patients without embolism (p less than 0.001). In the absence of a previous intervention, DVT did not produce any change in platelet count, while PE significantly reduced platelet number (p less than 0.008). In DVT patients without respiratory symptoms of embolism, we suggest that a lung scan should be performed when platelet count is lower than baseline value. For patients with a higher count, the probability of finding PE is very low, and scintigraphy is not cost-effective.

Adolescent↗

A rapid intraoperative estimation of the proliferative activity in brain tumors.

A technique for staining the nucleolar organizer regions (NORs) in tumor cells applied to smears from brain tumor biopsy specimens is described. This technique provides a rapid intraoperative evaluation of the proliferative activity in cerebral neoplasms and is a valuable complement to hematoxylineosin stained smears, supporting the criteria of benignity or malignancy in these tumors.

Brain Neoplasms↗

Natural killer cells in meningiomas.

A monoclonal antibody against the surface marker IOT-10 of natural killer (NK) cells was used to investigate the presence of these cells in a series of twenty intracranial meningiomas. In all of these tumours, IOT-10 positive NK cells were found in small numbers, mainly distributed among the tumor cells. Two recurrent tumors showed a relatively high number of immunostained cells. The data obtained in the present study suggest that a NK-cell-mediated immunological response can occur in meningioma tissue.

Adult↗

Syringomyelia-Chiari complex: magnetic resonance imaging and clinical evaluation of surgical treatment.

Thirty patients with syringomyelia-Chiari complex who underwent posterior fossa decompression or syringosubarachnoid shunting were studied clinically and by magnetic resonance (MR) imaging to assess the changes in the syrinx and in their clinical picture after surgery. When symptoms of posterior fossa compression were present, posterior fossa decompression was performed; however, when symptoms of posterior fossa compression were absent, the choice of posterior fossa decompression or syringosubarachnoid shunting depended, respectively, on whether the syrinx was narrow or wide on MR imaging. At least 1 year after surgery, subjective improvement or arrest of disease was recorded in 73% of the patients. The present study suggests that: 1) the symptoms attributed to spinal cord damage have no significant relationship to the size of the syrinx on MR images; 2) the surgical techniques employed in this series (posterior fossa decompression or syringosubarachnoid shunt) were equally useful in inducing syrinx collapse; and 3) when posterior fossa decompression is performed, plugging of the obex is not necessary for syrinx collapse.

Adolescent↗