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Biomedical subjects

M Espinosa

Publications and source records attributed to M Espinosa.

At least 145 records · Page 8Linked to original sources
PubMed1978

Early stages in Bacillus subtilis transformation: association between homologous DNA and surface structures.

The addition of ethylenediaminetetraacetate to competent cultures of Bacillus subtilis irreversibly inhibited the transformability as well as the cellular binding of DNA. Our results show that the inhibition of DNA binding by ethylenediaminetetraacetate in whole cells, protoplasts, and membrane vesicles is mainly due to a permanent alteration of the DNA receptors. Transformation absolutely requires free magnesium ions, whereas DNA binding is a magnesium-independent step. In contrast to ethylenediaminetetraacetate, the absence of Mg2+ does not irreversibly affect the capacity of the competent cells to be transformed DNA-binding receptors located at the cell surface remain associated with the plasma membrane after protoplasting and after isolation of membrane vesicles. A Mg2+-dependent endonucleolytic activity associated with the membrane appears to be responsible for the lower levels of binding by protoplasts in the presence of this ion.

Bacillus subtilis↗
PubMed1977

Comparative study of chromogenesis and endotoxin production from pathogenic Pseudomonas aeruginosa strains, isolated from neoplastic processes.

Several differences in relation to the chromogenesis and the production of endotoxins were found in Ps. aeruginosa strains, isolated from tumors. The strains isolated from neoplastic processes showed a higher amount of chromogenic fractions as compared with the control strains. Phenazinic compounds presented the main differences. Using two common methods of isolation and purification of Gram-negative endotoxin, we found a higher yield of these molecules in the case of tumor-isolated strains.

Animals↗
PubMed1976

Influence of several nucleotides on the competence development of Bacillus subtilis.

The influence of adenosine-3',5'-cyclic monophosphate (cAMP) and other nucleotides on the competence development of Bacillus subtilis was studied. The stimulation of competence which can be achieved by exposing physiologically low-competent cells to supernatants from highly competent cultures can be inhibited with different cAMP doses. When the same cells were suspended in a minimal medium with cAMP, varying degrees of stimulatin- of competence were observed depending on the time of addition of the drug. This effect is not specific for cAMP. It appears to be correlated to an increase of the amount of DNA bound to the competent cells. cAMP activities were antagonized by equimolar doses of adenosine-triphosphate (ATP) and guanosine-triphosphate (GTP).

Adenosine Triphosphate↗
PubMed1976

Competence in continuous cultures of Bacillus subtilis: inhibition by arginine and reversal of the inhibition by Mn2+.

Arginine inhibited the competence of Bacillus subtilis growing in a chemostat at a dilution rate of 0-277 h-1. The biosynthesis of competence-stimulating activity was only partially repressed. The inhibitory effect may be due to an alteration in the cell's capacity for being stimulated to competence and/or in its ability to take up DNA irreversibly. MnSO4 at 10(-6) M restored competence immediately.

Arginine↗
PubMed1975

Evaluation of different antibiotic actions combined with rifampicin. In vitro synergism against Pseudomonas and Proteus.

Associations of penicillin, streptomycin, tetracycline and polymyxin B with rifampicin were tested for synergism against Pseudomonas and Proteus pathological strains. The combination of rifampicin and polymyxin B was clearly synergistic for all strains as it was evaluated by isobolograms and killing curvesmthe bactericidal action of this association, without any cross-resistance between its components, may eradicate gram-negative bacteria infections with marked polyvalent drug resistances.

Drug Synergism↗
PubMed1975

Penicillin immunogenicity in the presence of different pharmaceutical adjuvants.

Preliminary results in the variations of the penicillin immunogenicity in the presence of aminosugars, polysaccharides and terpenic substances are presented and the decreasings of the potential antigenicity of the penicillin molecule appeared in the presence of hexosamine molecules are estimated. It might be possible as a consequence of modifications in the early immunogenic interactions between antibiotic and serum proteins of the hipersensitive animals.

Adjuvants, Pharmaceutic↗
PubMedDate not supplied

Development of infants born to cocaine-abusing women: biologic/maternal influences.

This study investigated the influence of gestational age, birthweight, caregiving, and maternal personality characteristics on the development of 51 six-month-old infants born to and being reared by cocaine-abusing mothers. Two self-report measures were administered to the pregnant women at intake: the ASI (quantifying drug use) and the MCMI (describing DSM-III Axis II personality characteristics and Axis I clinical syndromes). Infants' biologic vulnerability was assessed by gestational age and birthweight. Caregiving was assessed 6 months later in the home, using the HOME Inventory and maternal caregiving behavior rating scales. Infant development was assessed in the laboratory at 6 months using the Bayley Scales of Infant Development. Higher Bayley scores were associated with heavier birthweight and increased maternal sensitivity. Furthermore, mothers of infants with shorter gestations were found to be more sensitive caregivers, whereas mothers who reported more histrionic-gregarious, narcissistic, borderline-cycloid, and/or paranoid personality characteristics during pregnancy were less sensitive caregivers. Surprisingly, mothers who reported more depressive symptoms during pregnancy provided more sensitive care.

Adult↗
PubMedDate not supplied

Maternal ego development and mother-infant interaction in drug-abusing women.

The purpose of this study was to expand our knowledge about factors in substance-abusing women, other than chronic drug abuse, that may influence maternal caregiving behaviors. Specifically, the study explored relationships between maternal characteristics and mother-infant interaction in a sample of drug-abusing women to determine whether drug-addicted mothers' level of ego development affected mother-infant interaction at 1 month. Data collection occurred during a prenatal lab visit and 1 month postpartum and included a clinical interview, self-report on participants' addiction severity, clinical personality inventory, ego development test, and videotaped observation of mother-infant feeding interactions. Only ego development, and to a lesser degree psychological symptoms associated with substance abuse, were found to be significant predictors of maternal-child interaction at 1 month. This points to the need to focus on building internal resources in providing substance abuse treatment and other services for substance-abusing mothers.

Adult↗