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M C Vidal

Publications and source records attributed to M C Vidal.

At least 19 recordsLinked to original sources
PubMed2000

[Anatomic and morphological studies on the initiation of somatic embryos obtained from meristematic apexes of Musa sp.

The origin of somatic embryos obtained from meristematic apexes of the Musa (AAA) clone "Gran enano" was analyzed through histological and morphological studies during the various development phases of the process. The research point out that somatic embryos developed directly from perivascular parenchyma cells of the leaves. Histological sections of globular embryos showed a radial disposition to cell and the existence of an epidermal layer that surrounds the embryo completely. When citocinine (Z or BA) was added, some embryos remained in globular stage with mild signs of enlargement but with no later development of invagination. Other's embryos reached the invagination stage; and some reached the enlargement stage with active photosynthetic tissues. However there were no to generation of complete plant regardless of additional treatment, such as "osmotic shock" or the additions of GA3--At present do not have an explanations for this results. Therefore, additional experiment should be in early, intermediate and later stages of somatic embryogenesis, in order to understand the mechanisms underlying the lack of development of plants from somatics embryos.

Cloning, Organism↗
PubMed1996

Characterization of F3II, a sarcomatoid mammary carcinoma cell line originated from a clonal subpopulation of a mouse adenocarcinoma.

We characterized a new mammary tumor cell line, F3II, previously established in vitro from a clonal subpopulation of the BALB/c transplantable mammary adenocarcinoma M3, moderately metastatic to lung. The F3II cell line has been passaged > 50 times. It has grown as elongated cells adherent to the bottom of the flask. Cytogenetic studies showed that F3II cultures were nearly triploid. Tumor cells expressed fibronectin and showed high levels of cell-surface urokinase, a key protease in invasion and metastasis. F3II cells grew as poorly differentiated, spindle-cell carcinoma tumors (sarcomatoid carcinomas) with a prominent local invasiveness, a high angiogenic response, and a 90-100% incidence of lung metastases when inoculated s.c. into syngeneic mice. Ultrastructural and immunocytochemical analysis revealed characteristic features of carcinomas. Our data suggest that F3II is less differentiated and more aggressive than the original tumor line, supporting the notion that mammary carcinomas are heterogeneous neoplasms and contain subpopulations with diverse biologic behavior. The F3II mouse mammary sarcomatoid carcinoma line is a suitable model to examine antiinvasive, antiangiogenic, and antimetastatic agents.

Adenocarcinoma↗
PubMed1994

Effect of host-organ environment on the in vivo and in vitro behavior of a murine mammary adenocarcinoma.

We investigated the role that organ environment may play in determining the homing of disseminated cells from a murine mammary adenocarcinoma moderately metastatic to lung (M3). Conditioned medium (CM) from normal lung was able to enhance both local and metastatic growth. It increased the number of lung colonies when inoculated together with tumor cells via intravenous or separately via intraperitoneal route. Several in vitro studies were performed in order to elucidate possible mechanisms. It was shown that lung CM stimulated the in vitro growth and the migration of M3 cells. Normal kidney and liver CM lacked all these capacities.

Adenocarcinoma↗
PubMed1993

Altered calcium-binding ability of plasma proteins as the cause of hypocalcemia in lepromatous leprosy.

This paper reports a study performed on 10 lepromatous leprosy outpatients and on the same number of age- and sex-matched contacts. All of the lepromatous patients were hypocalcemic, but plasma levels of ionized calcium and the acid-base status were normal. The average daily food intake assessed through a questionnaire revealed adequate nutrition of patients and controls. Plasma proteins and 1,25-dihydroxyvitamin D3 and intestinal absorption of calcium were discarded as the causes of the hypocalcemia. In vitro experiments designed to investigate the effect of hydrogen ion concentration on the equilibrium between calcium ion and proteins revealed that, at normal pH values, plasma proteins from lepromatous leprosy patients bind a smaller fraction of total plasma calcium than those from controls. This phenomenon produces a normal concentration of ionized calcium that determines a normal parathyroid status as indicated by the normal urinary excretion of hydroxyproline and plasma concentrations of alkaline phosphatase (total and bone isoenzyme) and tartrate-resistant acid phosphatase.

Absorption↗
PubMed1990

Characterization of a new murine tumor variant with different in vivo behavior selected by its adhesive properties.

The purpose of the study was to determine whether the selection by adhesion to fibronectin (FN) also selects for cells with different tumorigenic and metastatic abilities. M3 murine mammary adenocarcinoma cells with moderate metastatic potential were seeded on FN-coated plastic substrates. Non-adherent cells were removed at 30 min, and the adherent ones were expanded in monolayer culture. Selected tumor cells were then harvested and inoculated sc into syngeneic mice. The selection procedure was repeated three times. After the third cycle, tumors were further maintained by sc trocar transplantation, and the variant obtained was called M3Ad. Although the in vitro selection was adhesion to FN substrate, the in vitro adhesion behavior of the variant M3Ad was identical to that of the parental tumor M3. However, the cytogenetic profile and the in vivo behavior indicated that M3Ad differed from M3. The distribution of the chromosome number of M3Ad cells revealed a lower mode and mean than of M3 cells. Moreover, the M3Ad variant exhibited a shorter latency, a higher growth rate and a lower incidence of spontaneous lung metastases. However, it produced significantly more and larger lung colonies than M3 after iv injection.

Adenocarcinoma↗
PubMed1990

In vivo selection and characterization of a murine mammary tumor subline with high potential for spontaneous lymph node metastasis.

A transplantable mammary adenocarcinoma, grown in Balb/c mice, with a marked enhancement in its draining lymph node metastatic ability (MM3LN), was obtained through an in vivo procedure from a variant tumor moderately metastatic to lymph nodes (MM3). Both MM3 and MM3LN presented a similar latency and tumor growth rate and reached the same tumor mean diameter at death. MM3LN tumor-bearing mice exhibited a larger mean survival time. The new variant showed a 2.5-fold higher incidence of tumor-draining lymph node metastases than MM3 line, with no differences in the incidence of lung metastases. Morphology as well as cytogenetic and in vitro adhesion properties were studied in order to characterize the new subline. This murine tumor model has potential application in the study of the metastatic process in lymphoid tissue.

Animals↗
PubMed1984

Respiratory alkalosis and reduced plasmatic concentration of ionized calcium in rats treated with 1,25 dihydroxycholecalciferol.

The daily administration of supraphysiological doses of 1,25 dihydroxycholecalciferol (0.1-2.5 micrograms/d/100 g body weight) to rats, produced respiratory alkalosis. With the doses of 0.1-0.2 micrograms/d/100 g and feeding a diet with 0.7% of calcium, calcemias did not exceed 2.75 mM, and significantly reduced plasma ionized calcium levels were measured. The latter phenomenon was found associated with increased urinary excretion of cAMP, soft tissue calcium content, and polyuria with hypostenuria, all known effects of parathyroid hormone. These effects were absent in thyroparathyroidectomized rats treated in the same fashion. Present results suggest that the stimulus of low levels of plasma ionized calcium overcomes the probably inhibitory effect of the steroid on parathyroid hormone secretion.

Alkalosis, Respiratory↗
PubMed1979

[Not Available].

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History, Modern 1601-↗
PubMed1972

CO 2 -fixing enzymes in a marine psychophile.

A psychrophilic marine Pseudomonas was found to contain phosphoenolpyruvate (PEP) carboxylase and an adenosine triphosphate-linked PEP carboxykinase. Some properties of these CO(2)-fixing enzymes were compared with those homologous enzymes from the terrestrial mesophile Enterobacter cloacae. The PEP carboxylases from both organisms were activated by acetyl-coenzyme A (CoA) and inhibited by l-aspartate. The enzyme from Pseudomonas was less dependent on the presence of the activator, but maximal activation was attained at acetyl-CoA concentrations much lower (50 mum) than those required to saturate the enzyme from E. cloacae. In both cases the main effect of acetyl-CoA was to decrease the K(m) value for PEP. The activity of PEP carboxylase from Pseudomonas was only slightly inhibited by NaCl, KCl, or NH(4)Cl up to 100 mm, whereas the enzyme from E. cloacae was inhibited by about 70% under similar experimental conditions. Both PEP carboxylase and PEP carboxykinase from Pseudomonas showed considerably lower thermal stability than their counterparts from E. cloacae. Our results suggest that the CO(2)-fixing enzymes from a marine Pseudomonas and E. cloacae are similar in nature and regulation, but they differ in properties related to the peculiar conditions of the marine environment.

Ammonium Chloride↗
PubMedDate not supplied

Third-generation cephalosporin resistance in Shigella sonnei, Argentina.

Shigella sonnei resistant to cefotaxime (but not to ceftazidime) was isolated for the first time in stool samples from a pediatric patient with vomiting and bloody diarrhea in northern Argentina. Microbiologic and biochemical tests confirmed the presence of an extended spectrum beta-lactamase displaying an apparent isoelectric point value of 8.2.

Argentina↗