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Biomedical subjects

F Molina

Publications and source records attributed to F Molina.

At least 19 recordsLinked to original sources
PubMed1995

Mutational fingerprint induced by the antineoplastic drug chloroethyl-cyclohexyl-nitrosourea in mammalian cells.

Using the pZ189 shuttle vector approach, we determined two chloroethyl-cyclohexyl-nitrosourea (CCNU)-induced mutation spectra (3 and 6 mM) in African green monkey kidney cells (CV1). One hundred and twenty-one independent clones (101 CCNU induced, 45 at 3 mM and 56 at 6 mM; 20 spontaneous) showing functional inactivation of the supF gene were analyzed. One hundred and five plasmids (91 CCNU induced, 41 at 3 mM and 50 at 6 mM; 14 spontaneous), showing no large deletion/rearrangements, were sequenced. Ninety mutants (81 CCNU induced and 9 spontaneous) showed at least one mutation in the supF region. The analysis of the 122 CCNU-induced mutations (56 and 66 at 3 and 6 mM, respectively) revealed that: (a) the majority of the mutations were GC-targeted base pair substitutions; (b) AT-targeted mutations were significantly more frequent in the CCNU-induced (6 mM) than in the spontaneous mutational spectrum (P < 0.0006, Fisher's exact test); (c) mutational spectra obtained at 3 and 6 mM CCNU were significantly different (P < 0.008); (d) induced mutations were nonrandomly located in both spectra and generated either a common hot spot (position 123, 5'-GGG-3') or hot spots exclusive for each CCNU concentration (3 mM: position 159, 5'-AGG-3'; 6 mM: position 109, 5'-GGG-3'); (e) the occurrence of GC-->AT transitions was significantly different as a function of CCNU concentration (P < 0.02, Fisher's exact test), the mutated G being almost exclusively preceded by a purine (5'Pu G) at 6 mM and by either Pu or Py at 3 mM; and (f) by applying Calladine's rules, we found that sequences encompassing the three CCNU hot spots shared identical helix parameters for no more than 2 bp steps 5' (or 3 bp steps 3') to the mutated G. Our results are consistent with the hypothesis that O6-alkylguanine is responsible, either directly or indirectly, for the majority of GC-targeted mutations, while O4-alkylthymine and/or N3-alkyladenine are probably responsible for AT-targeted mutations. The results suggest also that, in CV1 cells, the efficiency of the repair mechanism(s) involved in the removal of O6-alkylguanine is influenced by the DNA sequence context. All of these factors determine the CCNU mutational fingerprint. CCNU has been implicated in the induction of therapy-related leukemias.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1995

Immunoanalysis of human insulin using monoclonal antibodies reveals antigenicity of evolutionarily conserved residues.

Seven anti-human insulin monoclonal antibodies (mAb) were produced according to an efficient immunization protocol elaborated in our laboratory. Their affinity constants for the binding to the insulin molecule ranged from 5.0 x 10(8) M-1 to 1.0 x 10(10) M-1 when insulin was in solution and from 6.0 x 10(6) M-1 to 2.5 x 10(8) M-1 when insulin was adsorbed onto the microtiter plate. The antigenic sites on the insulin molecule recognized by these mAbs were mapped using two approaches. MAb pairs capable of binding simultaneously to human insulin in solution (using a two-site ELISA) or adsorbed onto a microtiter plate (using a competitive ELISA) were first sought. Three antigenic regions were defined on the surface of adsorbed human insulin and four on soluble insulin. Two distinct antigenic regions common to both the adsorbed and the soluble forms of insulin were defined by our mAbs. In a second approach, the immunological cross-reactivities of these mAbs with species variants of insulin, chemically modified insulin of known structure and a panel of 78 overlapping nonapeptides covering the entire sequence of human proinsulin were assessed. Evidence was obtained that the epitopes recognized by the mAbs included residues conserved during evolution in the insulin molecule. The epitopic specificity of one group of mAbs (group I) was precisely defined. This group recognized a highly conserved region of the insulin molecule including residues 10-17 of the A chain.

Amino Acid Sequence↗
PubMed1995

Mutated K-ras gene analysis in a randomized trial of preoperative chemotherapy plus surgery versus surgery in stage IIIA non-small cell lung cancer.

The observation that the proteins encoded by ras genes play a central role in the signalling pathways used by cells to respond to growth factors and the fact that mutated ras proteins are constantly promoting cell division have led to a PCR-based hunt for additional clinical information. In the present study, K-ras analysis draws the following conclusions: (1) K-ras point mutation frequency was higher in the surgery group (10 of 24 patients) than in the chemotherapy-surgery group (3 of 20 patients). (2) Mutated K-ras was predominantly observed at codon 12 but five mutations appeared at codon 61. (3) Mutations were identified in the squamous cell carcinoma histological NSCLC subtype except in four cases corresponding to adenocarcinoma. (4) A multifarious pattern of substitutions, especially at codon 12, were noted with aspartic K 12 substitutions more prone to develop bone metastases. (5) Although a genotypic K-ras classification of NSCLC may not yet be formulated, our accumulated data (unpublished) suggest a trend toward it. (6) Patients with mutated K-ras tumors in the surgery group had no different survival than those with normal K-ras. However our pooled data as well as other authors' results assert that mutated K-ras constitute an additional prognostic datum that deserves to be included together with TNM classification. In the design of new preoperative (neoadjuvant) chemotherapy trials, stratification of tumors by K-ras status deserves to be further investigated in order to correlate with response, relapse and survival. Mutated K-ras genotype merits further research. Finally, the paradigm of uneven histological distribution and mutated K-ras spectra among researchers should serve as a stimulus to search for further contributions in this field.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1995

Mandibular elongation and remodeling by distraction: a farewell to major osteotomies.

A modified technique for mandibular distraction is reported: an oblique corticotomy is made in the external cortex of the mandible at the level of the gonial angle. Two intraosseous stainless steel pins are inserted and are joined by a softer distraction screw. We make two corticotomies, one horizontal and one vertical, and insert three pins to achieve bidirectional distraction when the mandibular body and the ascending ramus are hypoplasic. This procedure has been used in 87 patients with unilateral hemifacial microsomia and 19 patients with bilateral mandibular hypoplasia. A mean elongation of 19 mm was obtained in the unilateral group. In the bilateral cases a mean vertical elongation of 7.5 mm and a mean horizontal elongation of 14 mm were obtained. A great improvement of the facial asymmetry was achieved in all the patients. The follow-up in this series varies from 3 months to 3 1/2 years (mean, 19 months in unilateral cases and 12 months in bilateral cases). No relapses have been observed.

Adolescent↗
PubMed1995

[Invasive pulmonary aspergillosis. Necropsy series].

Invasive pulmonary aspergillosis (IPA) is a severe infection which is usually diagnosed at postmortem examination. This infection occurs mainly in immunosuppressed patients, although it has also been reported in immunocompetent patients. Clinical records from patients diagnosed with IPA in our institution from 1983 to 1992 were retrospectively studied to analyse clinical and therapeutical characteristics of IPA. Sixteen episodes of IPA were recorded, all of them but one from necrotic specimens. A total of 18.7% of patients were immunocompetent, one patient had the acquired immunodeficiency syndrome (AIDS), and the remaining patients had a classical immunosuppression. Fever and dyspnea were noted in all patients; hemoptysis was recorded in 12.5% of patients. The predominant radiological pattern was a bilateral alveolar infiltrate (75%). Diagnosis was made at postmortem examination in 15 cases (93.7%), and a clinical premortem suspicion was obtained only in 25% of patients. IPA can occur in immunocompetent patients more frequently than considered until now. The suspicion index for IPA is low, even in immunosuppressed patients.

Adult↗
PubMed1994

Antiproliferative and synergistic effect of interferon alpha-2a, retinoids and their association in established human cancer cell lines.

The effect of 13-cis-retinoic acid (cRA) and all-trans-retinoic acid (tRA) used alone or in combination with interferon alpha-2a (alpha-IFN 2a) was tested on three established human cell lines: KB (epidermoid carcinoma of the oral cavity), SCC-25 (tongue squamous cell carcinoma) and MCF-7 (mammary carcinoma). Both retinoids significantly decreased cell proliferation (growth curves) and colony forming efficiency (CFE) in all cell lines, in a dose-dependent way (at a concentration ranging from 10(-5) to 10(-9) M) and differing from line to line, following the pattern: MCF-7 > SCC-25 > KB. Retinoids at any concentration (already at 10(-7) M) combined with alpha-IFN 2a (ranging from 100 to 500 IU/ml) were more effective in inhibiting cell proliferation than each of the two compounds alone. This was particularly evident with SCC-25 cells. Concerning MCF-7 cells, on the contrary, the effects produced by the association suggested a possible additive more than synergistic amplification of growth inhibition.

Breast Neoplasms↗
PubMed1994

Characteristics of the cytosol-synthesized proteins generating class-I-bound peptides.

The proteins synthesized in the cytosol are several thousand, and the number of peptides potentially able to be bound by class I molecules they can generate is therefore huge. On the other hand, the actual number of peptide-class I complexes required for CTL activation is around 200. We focused on the peptides bound by B27 molecules and by the whole class I. By comparing our results with analogous data from other laboratories, we found that 31 peptides matched protein sequences in data bases; in four cases, two peptides are derived from the same protein. The finding of four pairs of identical samples in a sampling of 31 peptides from a pool of unknown magnitude suggests that this pool is quite small. We have estimated the size of this pool by combinatorial analysis and by computer simulation, and we have found a most probable distribution of about 100 to the number of self-proteins that can actually generate peptides bound by class I molecules.

Amino Acid Sequence↗
PubMed1994

Molecular Probe Data Base (MPDB).

This paper provides an update on the contents and structure, forms and mode of data distribution of the Molecular Probe Data Base (MPDB), a database that collects and provides on-line information on the sequence, target gene, applications and bibliographic references of synthetic oligonucleotides. The recent data extension and the new means of accessing the database are discussed.

Base Sequence↗
PubMed1994

Minimal incision palatopharyngoplasty. A preliminary report.

A new palatopharyngoplasty which allows good muscular reorientation as well as elongation of the soft palate with minimal morbidity and scarring has been developed, and 66 selected patients underwent the procedure during the period September 1989 to March 1993. The most important findings were reduced operative bleeding, good length and mobility of the soft palate, and minimal scarring. A total of seven fistulas (11%) developed. Twenty-three patients (mean age 6 years and 2 months at the time of operation) underwent nasopharyngoscopy and multiview videofluoroscopy; velopharyngeal insufficiency was evident in only four (17%). Dental casts were obtained in 14 patients (mean age at the time of the operation 1 year, 3 months) who were followed up for a maximum period of two years. No postoperative orthodontic treatment was required and the width and harmony of the dental arch were maintained in all cases.

Adolescent↗
PubMed1994

Orbital hypertelorism.

Excessive distance between the orbits is only one manifestation of a complex deformity that affects several skeletal and soft-tissue structures. This article discusses the classification, preoperative planning, and surgical procedures used in the reconstruction of orbital hypertelorism.

Adult↗
PubMed1994

[Extrahepatic portal vein aneurysm and recurrent cholestasis].

Aneurysm of the portal vein is quite infrequent and its clinical manifestations is variable. The association between aneurysm of the extrahepatic portal vein and recurring obstructive jaundice has only been described on one occasion, one where there was also portal hypertension. One case of aneurysm of extrahepatic portal vein associated with recurring cholestasis is described. The diagnosis was performed via echography and abdominal TAC and confirmed by portal venography. There was no evidence of hepatopathy or portal hypertension. Possibly, the displacement of the biliary tract the portal vein is a contributing factor to recurring cholestasis in the present case.

Aneurysm↗
PubMed1994

A randomized trial of mitomycin/ifosfamide/cisplatin preoperative chemotherapy plus surgery versus surgery alone in stage IIIA non-small cell lung cancer.

The efficacy of surgery or radiotherapy as conventional treatment for stage IIIA non-small cell lung cancer (NSCLC) is limited. Recent studies have pointed out that preoperative chemotherapy may improve survival. To reconcile the two approaches, we undertook a multidisciplinary randomized trial to examine the possible synergism between preoperative chemotherapy and surgery in improved survival. Stage IIIA NSCLC patients were randomly assigned to receive either three preoperative courses of mitomycin/ifosfamide/cisplatin chemotherapy and surgery or surgery alone. The median survival was significantly greater in the chemotherapy plus surgery group than in the surgery group (26 months v 8 months; P < .001). However, the prognostic value of the mutated K-ras gene data presented awaits the analysis of larger sample populations. Similarly, the role of high-dose cisplatin in inducing higher pathologic complete remissions has to be corroborated in future randomized trials.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1993

Modulation of tensin and vimentin expression in chick embryo developing cartilage and cultured differentiating chondrocytes.

It has been proposed that tensin, in association with several other proteins, mediates the micro-filament-integrin link. Here we describe the isolation of clones spanning about 5 kb from the 3' end of tensin mRNA from cultured chick embryo chondrocyte and embryonic heart cDNA libraries. Tensin expression was investigated in cultured chick embryo cells. It was observed that tensin expression is dependent upon substrate adhesion and it is turned off after 7 days of suspension culture. This process is reversible. Tensin expression is also regulated during cartilage cell differentiation in vivo; at Hamburger and Hamilton stage 39-40, non-hypertrophic tibial chondrocytes express both RNA and protein while hypertrophic chondrocytes do not. In the culture system the expression of vimentin, a major component of intermediate filaments, showed an opposite behaviour since the suspension culture enhances the accumulation of both vimentin and its mRNAs. Therefore in chick embryo cultured chondrocytes and in vivo, during cartilage development, cell shape changes and/or integrin-extracellular matrix protein interactions may be involved in the regulation of these two genes coding for cytoskeletal proteins.

Amino Acid Sequence↗
PubMed1993

Solution structure of human plasma fibronectin under different solvent conditions. Fluorescence energy transfer, circular dichroism and light-scattering studies.

Human plasma fibronectin is a high molecular weight (530,000), multi-domain, modular glycoprotein, consisting of two nearly identical subunits disulfide-bridged close to their C-terminal ends. Three sites that can be differentially labeled with fluorescent probes are present on each fibronectin subunit, the transglutaminase-sensitive Gln3 residue and the two free sulfhydryl residues, Cys1201 and Cys2196. These sites are located, respectively, in the N-terminal heparin/fibrin-binding domain, between the central DNA and cell-binding domains, and just before the C-terminal fibrin-binding domain. To map the relative spatial arrangement of these domains, steady-state and lifetime fluorescence energy transfer techniques were employed. Our results show that the minimal intramolecular distances between the labeled Gln3-Cys1201 and Gln3-Cys2196 pairs are 5.5(+/- 0.6) nm and 5.7(+/- 0.7) nm, respectively, as measured by steady-state methods. Lifetime methods gave somewhat higher distances of 8.1(+/- 0.2) nm and 7.6(+/- 0.2) nm, respectively, between these sites. The binding of heparin or subjection to high ionic strength had only a minor effect, while in the presence of 50% (w/v) glycerol, an increase of about 25% in the intramolecular distances between these sites was observed. A similar effect was induced by binding of fibronectin to the surface of Cytodex beads, an event which was previously shown instead to markedly increase the intersubunit distances between the Gln3-Gln3 and Cys1201-Cys1201 pairs. The solution structure of fibronectin was further investigated by elastic light-scattering and circular dichroism measurements. By elastic light-scattering, the radius of gyration of fibronectin was found to be 15.3(+/- 0.8) nm in the presence of 30% (w/v) glycerol, in contrast to a value of 8.6(+/- 0.3) nm under physiological conditions. Far and near ultraviolet circular dichroism spectra showed that only minor changes in the secondary structure of fibronectin take place on increasing the glycerol content of the solvent up to 34% (w/v). Our results complement previously available information on the solution structure of fibronectin and on its transition from the native compact conformation to a more expanded form on increasing ionic strength or glycerol content. In either situation, fibronectin seems to retain a basic structural core, in which the N-terminal, the central and the C-terminal regions of the two subunits strongly interact with each other. A major role of hydrophobic forces, in stabilizing the fibronectin conformations under these conditions, is therefore postulated. The transition to the extended forms seen in many electron micrographs can instead be explained by disruption of the proposed structural core upon adsorption to surfaces.

Circular Dichroism↗