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Biomedical subjects

X Garcia

Publications and source records attributed to X Garcia.

16 recordsLinked to original sources
PubMed1998

Production of "neometalloenzymes" by de novo biosynthesis. New ELISA method for their characterization.

Several approaches known for producing "neometalloenzymes" are classified into two categories: protein engineering using antibodies as starting materials and "de novo" biosynthesis of metal-binding antibodies with potential catalytic metal-binding structure. This latter approach is chosen in this study. Polyclonal anti-zinc-iminodiacetate [IDA-Zn(II)] antibodies are produced in rabbits and mice. Because of the absolute need for the unequivocal screening of the hapten [IDA-Zn(II)] specific antibodies, a new ELISA method was developed using a biheaded polyethylene glycol with biotin on one end and the hapten on the other end. The parameters for optimizing the immunization and the ELISA technique are discussed and the method is validated with rabbit and mice sera.

Animals↗
PubMed1995

Actions of perezone on rat smooth muscle.

1. Perezone (PZN) on the in vitro intestinal smooth muscle of the rat relaxes the basal tonus of the smooth muscle, interrupts spontaneous activity and also blocks the contractile response induced by ACh, K+, and Ba2+; these actions are dose dependent. 2. Although in presence of small doses of PZN, the isometric contractile response to ACh was increased. 3. In calcium free intestinal smooth muscle preparation, the addition of PZN in low dose before Ca2+ increased the contractile effect of added calcium to the bath, but in presence of high doses of PZN the response to calcium was depressed. 4. PZN in calcium free preparations antagonized the contraction caused by adding barium. 5. These findings suggested that with small doses of PZN more availability of intracellular calcium free exist and/or an increase in excitability and/or an inhibition of AChase could coexist. 6. The responses of the intestine to high doses of PZN were possibly in part by blocking calcium entry. 7. The smooth muscle responses to PZN suggest that it has a membranal effect and/or an action on the internal calcium stores possibly increasing the intracellular calcium concentration. It is likely to be the expression of an increase in the intracellular calcium concentration above the levels normally reached that would be responsible for uncoupling of the smooth muscle, which would occur if the [Ca2+]i rises excessively.

Acetylcholine↗
PubMed1993

Wound healing in the fetal period: the resistance of the scar to rupture.

Wound healing in the fetal period is fundamentally different from that of the adult. In order to better understand this difference, we have studied wound healing in three types of wounds which are the most common in surgical practice, and have paid special attention to tensile strength in the scar. A sutured wound, a nonsutured wound, and an electrocautery burn were performed on a group of 30 rabbit fetuses with a gestational age of 23 days. Seven days later, the resulting scars were examined using histological, mechanical, and biochemical studies. The results were compared with those obtained in a group of 30 newborn rabbits and in a group of 30 adult rabbits who had had the same type of wounds performed on them. The body weight of operated fetuses was smaller than their control siblings. The sutured wound in the fetuses showed a more perfect macroscopic repair than in older subjects. However, the nonsutured wounds and the burns of the fetal group did not close. In the fetuses, the tensile strength of the sutured wound was 20% of the tensile strength of healthy skin. A similar relationship occurred in the group of adult rabbits. In the sutured wound of the fetal group, the synthesis of collagen was significantly less than in the adult group. The ratio between hydroxyproline (HYP) concentration in the sutured wound and HYP concentration in healthy skin was also significantly less in the fetal group than in the adult group.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1993

Influence of formamide on the electrical and mechanical properties of the guinea pig ventricle.

1. Guinea pig papillary muscle in vitro upon exposure of Formamide (FMD) exerts a dose dependent positive inotropic effect. 2. The increase in tension developed by papillary muscle is associated with a marked decrease in the duration of the action potential. 3. The increase in extracellular calcium concentration does not modify the positive inotropic effect, but increases the duration of the action potential. 4. FMD markedly potentiate the increase in tension induced by caffeine 3 M suggesting a possible synergetic effect upon the release of Ca2+ ions from the S.R. 5. These experiments suggest that FMD increases the intracellular calcium concentration by exerting a direct action on intracellular calcium stores.

Action Potentials↗
PubMed1992

Effect of the length of degenerating phrenic nerve fibres on the anaphylactic contraction of the diaphragm.

1. The effect of denervation on the anaphylactic contraction of the diaphragm from actively sensitized guinea pig has been studied. 2. The section of the phrenic nerve took place at cervical and thoracic levels. The sensitization of the animal took place several days before sectioning, simultaneously with denervation and after denervation. 3. The anaphylactic contractions were observed from the fourth day after thoracic denervation, and from the sixth day when denervation was in the cervical region. 4. The hypersensitivity to ACh in the denervated diaphragmatic muscle was present 24 hr after sectioning the phrenic nerve and reached its maximum 3-4 days after. 5. These results support the idea that denervation caused some changes in the membrane of the skeletal muscle fibres to allow the fixation of antibodies. These denervation changes are dependent on the length of the peripheral nerve left to degenerate. Anaphylactic contractions appeared earlier in those animals where phrenic nerve sections were closer to the diaphragmatic muscle.

Acetylcholine↗
PubMed1991

Immunological abnormalities in pediatric AIDS.

HIV infection of a fetus from an infected mother has severe immunological implications because it destroys still immature immune system. The abnormalities observed are precocious in the infants. When the infection occurs in perinatal period, clinical and immunological manifestations can present themselves at the age of 2-5 years. Two patterns of HIV infection can be distinguished. Humoral immunodeficiency is present in a high proportion of patients and leads to repeated bacterial infections and progression of the disease. Immunoglobulin substitution therapy improves clinical manifestations and can help to avoid viral replication.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Non-desensitizing in vitro anaphylactic reaction of chicken visceral muscle.

1. The contractions elicited in pieces of small intestine of actively immunized young chickens upon exposure to the specific antigen (Ag), or Schultz-Dale reaction, have been compared to similar responses of sensitized guinea-pig intestine. 2. Guinea-pig intestine responds, typically, with a large contraction to the first application of Ag. This is followed by a spontaneous relaxation of the preparation, while still in the presence of the Ag, and a rapid desensitization; i.e. further exposures to Ag fail to evoke new contractions. 3. In marked contrast, chicken intestine responds to the Ag with a contraction that remains at its maximal initial value for ca 5 min and then declines only slowly. 4. Exposure to the Ag does not desensitize chicken intestine, which relaxes upon washing out the antigenic protein but contracts again when this is re-introduced in the bath. 5. In addition, consecutive Schultz-Dale reactions of chicken intestine showed a consistent potentiation. They reached a maximal amplitude when the tissue was exposed to the Ag 5-7 times. Such a potentiation is abolished by storing the preparations for 24 hr at 4 degrees C. 6. These observations are discussed in terms of the known properties of avian antibodies.

Acetylcholine↗
PubMed1988

Ca2+-agonistic effects of diazepam, a benzodiazepine 1-4 derivative, on isolated mouse and guinea pig left atria.

In normal Krebs solution, diazepam (1.75X10(-4) M) increased the action potential duration in a reversible form and caused a positive inotropic effect on mouse auricular muscle (4). 2.) Further studies on diazepam action on electrical and mechanical activity of left auricular muscle from mouse and guinea pig, in preparations electrically driven, showed that diazepam induces an increase in action potential duration measured at 20% repolarization, a decrease in the rate of spike depolarization, and modifies the conduction velocity of the action potential. 3.) Diazepam produced in preparation with spontaneous activity, positive chronotropic and inotropic effects, and positive inotropic effect in electrically driven preparations. 4.) The change in action potential duration induced by diazepam on mouse preparations was higher than on guinea pig preparations, ca.X3. 5.) These findings support that diazepam action may be due to an increase in the inward calcium current and a reduction in the inward sodium current.

Animals↗
PubMed1988

Anaphylactic reaction in smooth muscle from the duck.

1. To know if the absence of desensitization in the chicken is characteristic of avian tissues, we studied the anaphylactic reaction in the duck. The contractions elicited in pieces of small intestine of actively immunized ducks upon exposure to the specific antigen, or Schultz-Dale reaction, were compared to similar responses of sensitized chicken and guinea pig intestine. 2. The smooth muscle from chicken actively sensitized contracts, when it is exposed in vitro to the specific antigen. Maximal tension, developed during anaphylactic reaction, is kept until the preparation is washed. New exposure of the muscle to the antigen causes it to develop tension again. This means that exposure to the antigen does not desensitize chicken intestine. 3. Intestinal smooth muscle from sensitized duck developed tension when the specific antigen was added to the bath; the tension was transitory and soon reached the basal line, even before washing the antigen. Contrary to the observations in the chicken smooth muscle, a second antigen dose failed to elicit a contraction of the duck intestine. Duck smooth muscle behaved like mammalian tissue. Exposure to the antigen desensitized duck intestine. 4. On multiple sensitized duck, the order of addition of antigens and their desensitization, did not alter the anaphylactic response to each antigen. 5. These observations are discussed in terms of the known properties of duck antibodies.

Acetylcholine↗