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E Mercado

Publications and source records attributed to E Mercado.

23 records · Page 2Linked to original sources
PubMedDate not supplied

Participation of DNA structure on sperm chromatin organization.

The in vitro interaction between purified bovine liver and sperm DNA with somatic histones, to form nucleosomes, and with bovine and salmon protamines were studied. DNAse or microccocal nuclease digestion of liver DNA-histone reassociated chromatin produced the expected polynucleosome type of fragments. Electrophoretic patterns of digested sperm-DNA nucleosomes were different. Micrococcal nuclease digestion produced mainly fragments smaller than 100 bp and some nucleosome-type particles. Under DNAse activity most of the products were smaller than 100 bp, indicating an increased susceptibility of the sperm DNA-histone complexes to the hydrolytic activity of both nucleases, particularly toward DNAse I. This differential susceptibility was confirmed by sucrose gradient spectrophotometric analysis. Acridine orange (AO) staining of histone-DNA reassociated nucleosomes showed significant differences in fluorescence intensity, sperm DNA-histone complexes being almost twice as fluorescent as liver DNA-histone complexes. On the contrary, liver DNA/protamine complexes stained with AO were consistently more fluorescent than sperm DNA-protamine complexes. Finally, no differences in either fluorescence intensity or spectra were observed when liver and sperm DNA were stained with AO after interaction with salmon protamines. The data suggest that sperm DNA has important structural characteristics that differentiates it from somatic DNA. These differences seem to be species specific and must surely play an important role on the determination of the dramatic sequence of that participates sperm chromatin organization.

Animals↗
PubMedDate not supplied

Prostatic cancer/benign prostatic hypertrophy. Subcellular distribution of estradiol/androgen receptors.

Six microsomal population of estradiol and androgen receptors have been characterized in human benign prostatic hypertrophy (BPH) and prostate cancer (PCa). Estradiol receptor (ER) and androgen receptors (AR) were extracted using 0.6 M KCL and determined by the dextran-coated charcoal method. ER and AR levels were smaller in BPH plasma membranes (PM) than in Pca cases. For functions 3, 4, 6, the ER values in PCa were 25-38% less with regard to BPH ER values. Whereas in PCa, AR values obtained in all fractions were higher when compared to BPH AR values. In benign prostatic hypertrophy and prostatic cancer, ER and AR levels were significantly higher in the nuclear fraction. In the nuclear fraction, ER and AR levels in BPH and PCa were significantly different. The subcellular distribution of AR and ER in BPH and PCa constitutes a reservation mechanism and processing a receptors for their continued growth.

Humans↗
PubMedDate not supplied

Human papillomavirus hpv-16 DNA as an epitheliotropic virus that induces hyperproliferation in squamous penile tissue.

The prevalence of human papillomavirus HPV-16DNA sequences in 57 penile carcinoma biopsies was examined using the polymerase chain reaction (PCR) with type specific internal probes, employing HPV consensus primers from the L1 region. The cases comprised 39 typical squamous cell carcinoma and 18 specimens with different subtype. PCR products were analyzed and HPV-16DNA was detected in a high percentage of specimens. Thirty-eight biopsies were HPV-16DNA positive. This determination was correlated with cellular differentiation and growth pattern. Our data corroborates that squamous cell carcinoma was invariably associated with HPV-16DNA.

Adult↗
PubMedDate not supplied

[Role of calcium in the regulation of syncytial formation and the formation of creatine kinase during the development of muscle in the absence of creatine].

1. It is demonstrated for the first time that typically elongated chick myotubes, with more than 20 nuclei per fiber and creatine kinase, appear in cultures fed all time with partially defined auto-conditioned medium. 2. It was found that the skeletal muscle enzyme of the chick embryo is independent of the presence of creatine and consequently is another constitutive enzyme like the creatine kinase of the early embryonic chick heart. 3. Calcium elicited the activity of the enzyme and promoted fusion of myoblasts in a creatine-free partially defined medium, in the absence of embryo extract. 4. It is suggested that creatine kinase is a dual molecule, working as an ATPasa in the absence of creatine with H2O as the nucleophilic reagent. 5. Alternatively, it is possible that creatine kinase can be synthesized and localized in advance to the advent of creatine in myocardial and skeletal muscle cells.

Animals↗