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A B Martínez

Publications and source records attributed to A B Martínez.

7 recordsLinked to original sources
PubMed2002

p16 Expression in squamous carcinomas of the tongue.

BACKGROUND: 81 patients with tongue carcinomas were studied to determine: 1). the proportion of carcinomas with altered p16 expression; 2). whether loss of p16 is an early carcinogenic event; 3). whether p16 expression alterations influence the prognosis. METHODS: 50/81 cases could be analysed by immunohistochemistry. RESULTS: Tumours were p16- in 32% (16/50) and p16+ in 68% (34/50) of patients; 32.3% (11/34) of p16+ tumours presented 1-10% of tumour cells as positive, 14.7% (5/34) 11-40% as positive, and 59.2% (18/34) presented 41-100% of tumour cells as positive. Adjacent nontumoural epithelium (ANTE) was available in 33 of the 50 immunohistochemically analysed specimens. ANTE was normal in 25 cases and dysplastic in 8 cases. In normal ANTE, p16 expression was positive in 16% (4/25) and negative in 84% (21/25) of cases. p16 expression was negative in all dysplastic ANTE samples (8/8). CONCLUSIONS: Changes in p16 expression are frequent in tongue cancer and can be detected at very early stages of carcinogenesis. Nevertheless, in our study neither the absence nor the degree of p16 expression influenced the survival of patients.

Adult↗
PubMed2000

Orally administered ethane-1-hydroxy-1,1-biphosphonate reduces the lethal effect of oral uranium poisoning.

Intoxication with uranium compounds is both an occupational risk for the workers engaged in the different processes of the elaboration of nuclear fuel and a risk for the population at large in terms of contaminated water and food. The toxic effects of uranium can be reduced by the administration of a biphosphonate, ethane-1-hydroxy-1,1-biphosphonate (EHBP), subcutaneously or intraperitoneally. The aim of the present work was to examine whether orally administered EHBP reduces the lethal effect of a single orally administered toxic dose of uranyl nitrate. Nine groups of 20 male Balb-c mice were used. Five groups received 350 mg kg(-1) of uranyl nitrate orally administered by gavage, four were co-treated 20 min later with EHBP either by gavage (350, 500, or 700 mg kg(-1)) or by subcutaneous injection (50 mg kg(-1)), and one group was not treated. Four groups of animals received only EHBP in doses and routes the same as those used in the intoxicated animals. Survival was assessed for 14 d. On day 14 the surviving animals of all groups were killed. An additional group of uranium intoxicated animals was killed on day 2 after the start of the experiment. Kidneys were examined histologically. On day 3 all the animals treated with uranyl nitrate alone and 20% of the animals treated with 700 mg kg(-1) of EHBP alone were dead. Survival at day 14 of the groups of mice intoxicated with uranyl nitrate and treated with EHBP (50 mg kg(-1) orally or 50 mg kg(-1) subcutaneously) was 45.0 and 49.6%, respectively. Tubule necrosis lesions were present in kidneys of mice intoxicated with uranyl nitrate, whereas lesions were less severe in mice treated with EHBP. Oral administration of EHBP is effective for reducing the lethal effect of uranium, and it is at least as useful as subcutaneous administration for prompt therapy of oral uranium exposure, achieving a survival rate of almost 50%.

Administration, Oral↗
PubMed1981

The subunit structure of chromatin fibres.

Optimal conditions for studying the ultrastructure of chromatin fibers of histone-containing spermatozoa in thin sections have been determined. Better results for preservation in sperm of the sea cucumber Holothuria tubulosa, have been found than in different frog species studied. The fine structure of chromatin fibers after different treatments was studied by computer materials. A clear superbead structure was found under all conditions which preserve the chromatin fibres. These have a diameter of 30 nm, with superbeads about 33 nm long. In the best preserved cases an additional periodicity of 11 nm along the fibres was found. There is no clear relationship of this periodicity with an eventual solenoidal structure of the chromatin fibers.

Animals↗
PubMed1976

Model studies of chromatin structure based on X-ray diffraction data.

Model calculations are presented in order to interpret the X-ray diffraction diagrams given by chromatin gels. It is shown that by taking into account the hydration of chromatin subunits, the problem of calculating the interference function in concentrated gels is greatly simplified. In this way it is spossible to fully interpret the influence of concentration on the position and intensity of the various rings present in the X-ray diffraction patterns. The possibilities and limitations of models based on spherical symmetry are also discussed. It is concluded that each chromatin subunit most likely contains three turns of DNA in each 200 base pairs segment surrounding a central protein core. With the method presented here it is possible to test if other models of chromatin based on different kinds of evidence are compatible with the X-ray diffraction data.

Chromatin↗
PubMedDate not supplied

[Epidemiological aspects of bilateral retinoblastoma].

Retinoblastoma (RB) is the most frequent solid tumor in the Instituto Nacional de Pediatría, México (INP). The bilateral presentation occurs in 25% of all patients. We present some epidemiological data of this form of the disease, in learn these epidemiological variables in our series. We reviewed the clinical charts from 1972 to 1994. We analyzed age, sex, timing of presentation of the second affected eye, positive family history, clinical staging, and the development of secondary malignancies. A total of 105 cases were detected from 412 RB total cases (25%). We observed a male predominance 1.6:1.0 p = 0.04 versus females. The clinical staging showed: retinal stage 9/102, ocular stage 58/102, orbital stage 26/102 and non classified 9/102 p < 0.00001. The asynchronous form is a rare presentation in our experience: 16/105 cases p = 0.00001 (15%). Only 16/105 patients had a positive family history of RB (15%). We found 2 of 105 cases with secondary malignancies (0.01%). The asynchronous form constitutes a rare presentation. We cannot explain the etiology for the high prevalence of bilateral disease. The frequency of secondary malignancies is lower than that reported in the literature.

Age Factors↗