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Biomedical subjects

R Mercado

Publications and source records attributed to R Mercado.

At least 37 records · Page 2Linked to original sources
PubMed1991

[Application of a system of serological surveillance of Chagas disease in a region of high chagasic endemia. I. Prevalence of Trypanosoma cruzi infection in Salamanca].

A serologic study for prevalence of Chagas infection was performed in Salamanca, Northern Chile. Indirect immunofluorescence and indirect hemagglutination reactions were used in samples from 1529 females and 698 males representing 10% of the population. A total of 499 positive results were obtained. The incidence of infection increases at a mean rate of 1% per year up to age 30, declining slowly in older groups to reach a maximum of 39.7% for the population. These data will be used to implement appropriate serologic surveillance programs and sanitary control measures in this and other populations.

Adolescent↗
PubMed1989

Hydatidosis diagnosis by double diffusion in agar with arc 5 detection.

To further assess the double diffusion arc 5 (DD5) test for human hydatidosis, the test was performed on sera from 45 patients with surgically confirmed hydatidosis and 54 with other pathologies in Santiago, Chile. Combined with tests reported previously, this brought the total number of study subjects with confirmed hydatidosis to 98 and the total with other pathologies to 128. Overall, the test yielded positive results with sera from 55 (56%) of the 98 serologically confirmed cases, the degree of seropositivity among patients with pulmonary hydatidosis (36%) being relatively low. The criteria adopted for a positive result were the presence of arc 5 or, in the absence of arc 5, the presence of three or more bands of precipitate. On the basis of these criteria, no false positive results were detected using sera from the 128 patients with other pathologies. It is concluded that using the DD5 test to diagnose hydatidosis in clinically selected individuals can provide results of high specificity; i.e., positive results can be taken as confirming presence of the infection. On the other hand, a negative DD5 result does not constitute definite proof that no hydatid cysts are present.

Adolescent↗
PubMed1979

Low-dose preoperative radiation therapy in carcinoma of the supraglottic larynx.

Seventy patients treated for all stages of carcinoma of the supraglottic larynx were analyzed retrospectively. A preoperative dose of 3,000--3,600 rads was given in 15 to 18 treatments over three to four weeks and surgery carried out four weeks later. The 5-year disease-free survival rates were approximately 75% in patients with early disease and 50% in those with more advanced disease. Survival with early disease was similar to that achieved by radical radiotherapy alone, while survival with advanced disease was similar to that achieved by surgery alone. These results suggest that low-dose preoperative irradiation is of limited value.

Aged↗
PubMed1979

Cancer of the breast. Radiation therapy.

There are many questions that have to be answered concerning the role of radiotherapy in the management of primary breast cancer. Hopefully, prospective clinical trials will provide some answers, but more basic research into the biology of breast cancer and the host-tumor relationship will be needed. There are indications that radiotherapy alone, or following minimal extirpative surgery in selected cases, may be as effective for control of breast cancer as conventional mastectomies. The role of radiotherapy following segmental mastectomy, with or without axillary dissection, needs to be clarified. The possibility exists that high LET (linear energy transfer) radiation such as neutron or pi meson beams may provide better local control than conventional radiation. Thus, it may be possible to treat effectively all primary breast cancers with such radiations and obviate the need for any type of mastectomy. It remains to be demonstrated whether adjuvant chemotherapy is as effective as radiotherapy in preventing chest wall and regional node recurrences. If it is not, there may be a place for both adjuvant chemotherapy and radiotherapy in the treatment of operable cancer of the breast. Likewise, effective chemotherapy combined with radiotherapy may increase the local and regional control achieved with radiotherapy alone and make more primary lesions suitable for treatment without mastectomy. Meyer (1970) recently called attention to the leukopenia and cellualr immune deficiency produced by irradiation to the thorax and mediastinum. Further study is necessary to define exactly how much immunosuppression results from radiotherapy, its clinical significance and what can be done to avoid or counter it. If Stjervsward's thesis (1974) concerning the deleterious effects of radiotherapy on survival is correct, then it is of great importance to identify those patients most likely to be adversely affected by radiotherapy. Conversely, it may be possible in the future to identify a subgroup of patients who would not be adversely affected by radiation and who would be most likely to benefit from it.

Breast Neoplasms↗
PubMed1978

Cancer of the nasopharynx in children.

The authors present 15 children with cancer of the nasopharynx. Of seven patients with primary epidermoid carcinomas, only two are alive and well. Only one of four patients with a primary soft tissue sarcoma is alive and well. Two of four patients with lymphoma of the nasopharynx are alive and well. All deaths were due to uncontrolled distant metastases. Only one patient (rhabdomyosarcoma) died with uncontrolled local disease. Radiotherapy to the primary and neck is recommended for all children with primary malignancy of the nasopharynx. Adjuvant chemotherapy may also be of value for all patients regardless of histopathology.

Adolescent↗
PubMed1977

Severe sodium depletion syndrome during lithium carbonate therapy.

Lithium carbonate, useful in the treatment of manic-depressive disorders, can produce nephrogenic diabetes insipidus. The drug, therefore, has been used to facilitate renal waster excretion when severe hyponatremia occurs in the syndrome of inappropriate antidiuretic hormone secretion. Symptomatic dilutional hyponatremia developed in a patient with pulmonary carcinoma whom we treated. Lithium carbonate was administered and renal sodium wasting, hypovolemia, and hypotension occurred. Hyperkalemia was also observed, and since adrenal steroid levels were not decreased, impairment of distal tubular function was suggested. Lithium carbonate blocks antidiuretic hormone effect by decreasing collecting duct cyclic adenosine monophosphate generation. These observations suggest that more generalized inhibitory effects on renal tubular function may also result from its use. An alternative drug, demeclocycline, may be preferable.

Carcinoma, Squamous Cell↗
PubMed1975

Rodent control programmes in areas affected by Bolivian haemorrhagic fever.

Bolivian haemorrhagic fever (BHF) caused by Machupo virus is acquired by contact with the excretions and secretions of Calomys callosus, an indigenous cricetine rodent which is preadapted to peridomestic habitats. It competes successfully with Mus musculus, but not with Rattus rattus. A successful disease control programme has functioned in Beni Department since 1964. It is based on trapping surveys and the detection of splenomegaly in Calomys rodents as an index of chronic virus infection. Mass trapping and poisoning are used initially, and regular trapping is employed to control Calomys populations in towns where disease has occurred. More than 1000 cases of BHF were recorded from 1960-1964, but less than 200 in the past 10 years. The cost of this programme is approximately $30 000 annually.

Animals↗