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Biomedical subjects

A Dueñas

Publications and source records attributed to A Dueñas.

At least 19 recordsLinked to original sources
PubMed1997

Effect of 4-aminopyridine and 3,4-diaminopyridine on guinea-pig isolated ileum.

1. 4-Aminopyridine and 3,4-diaminopyridine produced concentration-dependent contraction on guinea-pig isolated ileum incubated in Tyrode solution. The EC30 values were 1.14 x 10(-4) and 1.39 x 10(-4) M, respectively. 2. Calcium channel blockers such as verapamil, diltiazem, nifedipine, flunarizine, and lanthanum chloride antagonized the contracting effect induced by 4-aminopyridine and 3,4-diaminopyridine in guinea-pig isolated ileum. 3. Diazoxide and atropine sulphate behaved similarly as antagonists of the contracting effect induced by 4-aminopyridine and 3,4-diaminopyridine in guinea-pig isolated ileum. 4. It is concluded that the aminopyridines exert their effects through the release of acetylcholine from parasympathetic nerve terminals.

4-Aminopyridine↗
PubMed1997

[Sequential chemotherapy and radiotherapy in the treatment of locally advanced carcinoma of the head and neck].

In patients with non-resectable carcinoma of the head and neck, radiotherapy produces an average survival of 12 months. Neoadjuvant chemotherapy followed by radiotherapy has been shown to prolong survival and preserve organ structure and function, and to reduce systemic relapses in patients with advanced, resectable disease. An analysis was made of 35 patients treated with sequential chemotherapy and radiotherapy, 20 with non-resectable disease and 15 with resectable disease who refused surgery. Treatment consisted of 4 cycles of cisplatin + 5-fluoruracil in a 96-h continuous intravenous infusion in 16 patients, and the same treatment with leucovorin in 19 patients. After chemotherapy, the patients underwent cobalt irradiation of the primary tumor and neck. Chemotherapy produced a complete response rate of 46% and a partial response rate of 28%, yielding an overall rate of 74%. After radiotherapy, the CR increased to 63%. After 92 months of maximum follow-up, overall survival was 20% and median survival was 25 months. Locoregional relapses were the main cause of treatment failure. Our results suggest that sequential chemo-radiotherapy achieved encouraging CR rates with no significant increase in toxicity, prolonged survival in non-resectable patients, and enabled organ preservation in patients with resectable disease.

Adult↗
PubMed1994

An X-protocol based medical teleconsultation system using low or high speed networks. A specific-design approach.

The objective of this proposal is to provide solutions for the necessities of teleconsultation or telediagnosis among medical professionals, using work stations within the X-Windows environment and applicable in communication lines with an extensive range of bandwidths and operating system independence. Among the advantages sought are savings in transportation, improvement in the quality of the medical attention provided and continued training for the medical professional.

Computer Communication Networks↗
PubMed1993

An ODA-based coder/decoder for multimedia medical documents.

This paper describes the prototype of a coder/decoder based on the Open Document Architecture (ODA) standard for management of medical documents, as well as the working environment in which it has been developed. The prototype has been assessed in an X-Windows-equipped workstation with a relational database containing patient folders (text and still images) from the departmental information system of the liver transplantation unit.

Humans↗
PubMed1989

Effects of several neuroleptics, antidepressants and monoamine uptake blockers on ATPase activity and related oxygen uptake in rat brain in vitro.

An experimental trial was conducted to study the effects of phenoxybenzamine, cocaine, carbamazepine, loxapine, clozapine, clothiapine, thiothixene, droperidol, alprazolam, imipramine, maprotiline, dibenzepin, nomifensine, trazodone, mianserin, viloxazine, doxepin and amoxapine on photocolorimetrically rated ATPase activity and on related oxygen uptake, determined by manometrical means, within a concentration range of 0.1-0.001 mM. Phenoxybenzamine, clothiapine and maprotiline at 0.1 mM inhibited sodium-potassium ATPase activity and related QO2 by 30-40%. Loxapine, trazodone, amoxapine and alprazolam at 0.1 mM inhibited sodium-potassium ATPase activity by 25-35%. Imipramine, nomifensine and droperidol at 0.1 mM inhibited QO2 by 20-35%. Cocaine, at all concentrations assayed, inhibited ouabain insensitive ATPase. The remaining drugs did not produce significant modifications.

Adenosine Triphosphatases↗
PubMed1989

[Tissue concentrations of beta-methyl-digoxin in children].

Beta-methyl-digoxin concentrations in adipose, skeletal muscle and myocardial tissues, were studied in 8 patients undergoing by-pass surgery because of congenital heart disease. Correlation between doses/kg, plasmatic and tissue concentrations were analysed. We found statistically correlation between doses/kg and plasmatic concentrations; doses/kg and skeletal muscle concentrations (p less than 0.01); plasmatic and skeletal muscle concentrations (p less than 0.05). Concentrations was significantly greater in myocardial than adipose tissue before extracorporeal circulation (p less than 0.01); and significantly greater than adipose (p less than 0.01) and skeletal muscle (p less than 0.05) tissues after extracorporeal circulation. Extracorporeal circulation lessens adipose and skeletal muscle concentrations, but increases myocardial concentrations significantly (p less than 0.05). It is concluded, that the behaviour of beta-methyl-digoxin, in relation with tissue concentrations, is similar to digoxin.

Adipose Tissue↗
PubMed1989

[Ischemic heart disease. Its incidence and association with risk factors].

Cardiovascular diseases are the first cause of death in all developed countries and in many underdeveloped countries (1). In Cuba they have constituted the first cause of death in the last 20 years, with a tendency to increase, with the characteristic that this tendency is due to ischemic heart disease (IHD) (2). The frequency of IHD increases with age, but it has increased in the population under 50 years of age lately (3, 4, 5). Although the cause of atherosclerosis is unknown, in the last years an epidemiologic association has been demonstrated between the atherosclerotic disease (mainly IHD) and a series of pathologies, habits of the population, genetical, biochemical, physiological and environmental factors, which influence directly and indirectly the early development, frequency, severity evolution and prognosis of IHD and have been called coronary risk factors (CRF); at present, the disease is considered to be multifactorial and its magnitude and severity are influenced by the exposure time and the combination of CRF; it has also been demonstrated that it is decreased by the application of measures for the pressure measurements with Hg sphygmomanometer, in the population (1, 5, 6, 7, 8, 9, 10, 11). In our country, a series of studies have been made to ascertain the magnitude and characteristics of cardiovascular diseases (12-14); through these works we will know the incidence of IHD, some of its characteristics and its relation with some coronary risk factors hypercholesterolemia, arterial hypertension, (AH), diabetes mellitus, smoking habit and obesity).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Effect of trazodone on oxidative metabolism of rat brain in vitro.

Oxygen uptake of rat brain homogenate was reduced by 1 mM trazodone, a new atypical antidepressant. Na,K-ATPase activity and the associated oxygen consumption of rat brain slices were also reduced. Oxygen consumption of rat brain slices was enhanced by dopamine and this effect was blocked by 0.0001 mM trazodone. This drug uncoupled oxidative phosphorylation.

Animals↗
PubMed1976

Etiology of respiratory tract infections in children in Cali, Colombia.

One hundred eighty children hospitalized for acute respiratory disease were studied in Cali, Colombia. In the majority of patients, pneumonia was the reason for hospitalization and remained the final diagnosis. Fifty-one cases of pneumonia of indeterminate etiology comprised the largest single diagnostic category, followed by 38 cases of pneumonia associated with measles, and 22 cases assocaited with serologic evidence of infection with other viral agents or Mycoplasma pneumoniae. Etiologic diagnosis could be assigned with a reasonable degree of confidence in 116 of the 180 patients (64%). The laboratory procedure found most likely to provide the etiologic diagnosis in this series was paired sera specimens for demonstration of rise in antibody titer against the common viral respiratory pathogens. Those most frequently implicated serologically as etiologic agents in the cases studied were, in order of decreasing frequency, measles, influenza, parainfluenza, and adenoviruses.

Adolescent↗
PubMed1975

Mortality from tuberculous meningitis reduced by steroid therapy.

In this study of 99 tuberculous meningitis patients from Cali, Colombia, treatment with steroids (in conjunction with antituberculous drugs) was shown to be more effective in reducing mortality than treatment with antibacterial drugs alone. Results further suggest that low dosages of steroids (1 mg/kg of prednisone daily for r 30 days) are equally effective in treating the disease as high dosages (10 mg/kg of prednisone at the start of treatment, gradually reduced over a 30-day period). These results are band 4(-43 and -kk mg/100 ml) demonstrated cerebral release. Arterial blood hyperammonemia can be detoxified safely in the brain as long as the levels do not exceed approximately 300 mug/100 ml. Beyond that level lactic acidosis is observed, particularly in cerebral venous drainage. Arterial blood hyperammonemia was also related to the extent of alveolar hyperventilation. These findings are very similar to those seen in experimental hyperammonemia and support the concept that neurotoxicity in children with Reye's syndrome is at least partly due to impaired oxidative metabolism secondary to hyperammonemia.

Adolescent↗