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Biomedical subjects

G Merino

Publications and source records attributed to G Merino.

At least 37 records · Page 2Linked to original sources
PubMed1993

Precise deletions in large bacterial genomes by vector-mediated excision (VEX). The trfA gene of promiscuous plasmid RK2 is essential for replication in several gram-negative hosts.

We have developed a simple and efficient method of vector-mediated excision (VEX) for in vivo generation of precisely defined deletions in large bacterial genomes. The system uses homologous recombination with small cloned fragments on specialized pVEX plasmids to insert directly repeated bacteriophage P1 loxP sites at positions flanking the region to be deleted. In the presence of Cre recombinase, the loxP sites are efficiently recombined to produce the deletion. Deletion endpoints can be directed to specific nucleotides because they are defined by the termini of small homology-bearing fragments cloned into the pVEX plasmids. We have used VEX to delete trfA, the only known replication initiator gene of the 56.4 kb broad host-range plasmid RK2. The RK2 delta trfA mutant was found to be conjugation proficient, but unable to replicate in the RK2 hosts Acinetobacter calcoaceticus, Caulobacter crescentus, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Pseudomonas putida, Rhizobium meliloti, or Rhodobacter sphaeroides. These results show that trfA is essential for replication in these hosts and indicate that the broad host-range of RK2 does not involve multiple replicons.

Conjugation, Genetic↗
PubMed1992

[Correlation between ultrasound and pathology of the gallbladder].

Ultrasound is a sensible and specific method for the diagnosis, study of natural course and follow up of medical treatment of gallstones. Thus it is important to specify the concordance between echographic and pathological findings of the gallbladder. Ninety one patients were subjected to an ultrasound gallbladder examination immediately before elective surgery and the excised organ was pathologically examined right after the operation. The number and size of stones, the diameters and wall thickness of the gallbladder and the presence of polyps and septa were compared with both methods. The correlation was fair for the number or size of the stones considered separately; however the correct diagnosis of both parameters was obtained in only a third of the cases. Diameters of the gallbladder were underestimated by ultrasound; wall thickness measurement showed a very good correlation with both methods. No correlation was found for polyps or septa. Although ultrasound is excellent for the diagnosis of gallstones, its precision, is insufficient to determine the exact number and size of the stones.

Cholelithiasis↗
PubMed1984

Quantitative evaluation of the human spermatozoal motility and acrosome reaction in infertile oligozoospermic and fertile euspermic men.

Idiopathic oligozoospermia is one of the most important problems in Andrology, but up to now it is poorly understood because the often routine conventional semen parameters, unquestionably are not directly related to the evaluation of the morphological and functional integrity that determines the spermatozoan fertilizing capacity. A non complex strategy was designed to determine the presence of alterations in the functional integrity of the spermatozoa from infertile men with idiopathic oligozoospermia and from euspermic fertile men, by the quantitative analysis of the spermatozoan motility and the acrosome reaction. There was a lower percentage of acrosome reacted spermatozoa within the semen of the infertile men, accompanied with a significant decrease in the motility percentage, sperm velocity and motility index in comparison with semen from fertile men. These data strongly support a possible detrimental structural and functional integrity of the spermatozoa from the oligozoospermic men.

Acrosome↗
PubMed1983

[Evaluation of nutritional potential of fish in diets based on beans (Phaseolus vulgaris) and a cereal/corn (Zea mays) and/or rice (Oryza sativa)].

p6e complementation between corn and fish, and rice and fish was evaluated for the purpose of establishing the required levels of each constituent in the mixture to obtain the optimum value in the biological evaluations for each diet. The optimum fish levels were around 10 and 6% for the corn and rice diets, respectively. Complementary levels of fish in the bean: corn and bean:rice diets were evaluated in the same manner. The best values in the biological evaluation were obtained with only 2% of fish. The economical analysis of these mixtures revealed that the nutritional value of the Central American rural diets can be increased with the introduction of fish in small quantities in the habitual diets, without increasing the family food expenses.

Animals↗
PubMed1980

Abnormal prolactin levels in serum and seminal plasma in infertile men.

The role of prolactin in male infertility was studied in 33 patients in whom serum and seminal plasma prolactin levels were determined. With the exception of those patients with Klinefelter's syndrome, infertile males presented moderate hyperprolactinemia as compared with a control group of 34 men. Prolactin levels in seminal plasma were greater than in serum in all patients studied; however, prolactin levels in infertile patients were significantly less than in normal males. Therefore, this situation is the reverse of what happens in serum. Seven patients with idiopathic oligospermia were treated with 5 mg of bromocriptine daily during 6 months, resulting in no measurable effect on the sperm count. Infertility in men may be associated with moderate hyperprolactinemia but bromocriptine is of no therapeutic use. Interpretation of the abnormal levels of prolactin in seminal plasma in oligo- and azoospermic men requires further investigation.

Adult↗