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Biomedical subjects

F Martin

Publications and source records attributed to F Martin.

At least 289 records · Page 16Linked to original sources
PubMed1993

Surface phenotype and functions of tumor-infiltrating dendritic cells: CD8 expression by a cell subpopulation.

Although the function and significance of tumor-infiltrating dendritic cells (TIDC) in the immune response to tumor have never been clearly demonstrated, their location suggests that they play a critical role in the presentation of tumor antigen to specific T cells. We studied the morphological and functional characteristics of interstitial dendritic cells (DC) located inside tumors obtained by injection of cancer cells into syngeneic rats. Single and double immunostaining of tumor sections revealed a dense network of cells which expressed class II major histocompatibility complex (MHC II) molecules. Cell morphology and surface markers were characteristic of DC populations in other tissues. These DC were in close contact with tumor cells and increased in number as the tumor grew larger. Unexpectedly, a subpopulation of morphologically characteristic TIDC expressed both CD8 and MHC II molecules. TIDC were purified from tumors by gradient centrifugation and immunobeads and characterized by morphology, ultrastructural study and surface markers studied by flow cytometry. TIDC were negative for the CD5 molecule (a pan T cell marker), and were not labeled with 3.2.3 monoclonal antibody (mAb) (an NK cell marker) or with Ki-M2R mAb (a macrophage marker). A subpopulation of TIDC expressed the CD8 molecule, confirming the in situ results. TIDC expressed high levels of class I and class II MHC molecules and the adhesion molecule ICAM-1. This expression is compatible with effective antigen presenting function. Purified TIDC triggered rapid and high levels of proliferation of tumor-immune T cells in vitro, demonstrating the potential of these cells to constitutively process and present tumor-associated antigens.

Animals↗
PubMed1993

Automated ribosomal DNA fingerprinting by capillary electrophoresis of PCR products.

Capillary electrophoresis (CE) provides a rapid and automated technique for the analysis of subnanogram amounts of DNA fragments generated by the polymerase chain reaction (PCR). Here we describe the implementation of size-selective CE for DNA profiling and restriction fragment length polymorphism analysis of amplified polymorphic spacers of ribosomal DNA from fungi. Separations of unpurified and isopropanol-precipitated PCR-amplified DNA fragments in the size range of 20-1600 base pairs were achieved in less than 20 min with the use of hydroxypropyl methylcellulose as a sieving medium. The amplified internal transcribed spacer (ITS) and intergenic spacer (IGS) of RNA genes could be sized by coelectrophoresing a standard size ladder mixed with every sample, thereby eliminating errors in size estimation. This, together with the strictly controlled conditions of CE, permit the discrimination of amplified rDNA fragments differing only a few base pairs in length. Inter- and intraspecific variation in the size and number of restriction sites of the amplified rDNA spacers from the ectomycorrhizal basidiomycetes Laccaria laccata and Laccaria bicolor was observed and most strains could thus be reliably genotyped by PCR-CE. Multiple amplified IGS fragments of heterogeneous size were detected in several strains. This polymorphism is due to the occurrence of 5S rDNA subrepeats (i.e., multiple annealing of primer) within IGS. With CE, in contrast to slab gel electrophoresis, run times are short, the capillary can be reused, and full automation is feasible. Data acquisition and analysis are computer-controlled, which facilitates the locus identification and reduces error especially when large numbers of PCR products must be analyzed.(ABSTRACT TRUNCATED AT 250 WORDS)

Autoanalysis↗
PubMed1993

A comparison of the effect of lorazepam on memory in heavy and low social drinkers.

The cognitive deficits, particularly memory impairment, observed in association with organic brain damage caused by chronic alcohol ingestion, are consistent with the profile of benzodiazepine-induced amnesia. This study examined the cognitive capabilities of a group of heavy social drinkers (n = 11) and a group of low social drinkers (n = 11) under the influence of a pharmacological challenge (lorazepam 2 mg) and a placebo treatment. Lorazepam impaired visual memory and verbal learning in both groups, but the effect of lorazepam was exacerbated in the heavy social drinkers for delayed recall of verbal material. Heavy social drinkers had lower verbal fluency scores and were less able to copy complex figures than low social drinkers whether or not the pharmacological challenge was present. Lorazepam induced deficits, in both groups, which confirmed to the classic profile of those observed in benzodiazepine-induced amnesia. The deficits, both in the absence and presence of lorazepam, shown by heavy social drinkers suggest that changes may have occurred in their brain functioning.

Adult↗
PubMed1993

A comparison of the amnesic effects of lorazepam in alcoholics and non-alcoholics.

The transient amnesia produced by lorazepam has been suggested to have much in common with the permanent amnesia associated with organic brain damage. The present study examined the amnesia associated with chronic alcoholism and acute lorazepam administration and hypothesised that because alcoholics have prior impairment, their response to lorazepam induced amnesia would differ from that of non-alcoholics. Memory functioning was tested in 20 chronic alcoholics and 20 non-alcoholic controls both before and after administration of either 2 mg lorazepam or a placebo. It was found that, although there were some discrepancies on some of the memory tests, both long term alcohol abuse and acute lorazepam administration impaired visual and verbal episodic memory but did not impair semantic or short-term memory (STM).

Adult↗
PubMed1993

Survey of butyltin contamination in Portuguese coastal environments.

Butyltin compounds (MBT, DBT and TBT) in intertidal sediments collected in four different Portuguese coastal environments have been measured in order to evaluate the extent of contamination. The sites chosen were the Rias of Aveiro and Faro, and the Sado and Tejo estuaries. These zones were traditional areas for shellfish production in the recent past, but the effects of industrial development have caused a deterioration of the environment. Specific contaminations were derived from the harbour (commercial and/or fisheries) and shipyard activities, resulting in a release of TBT and causing the oyster populations of the above mentioned estuaries to almost disappear. Results presented in this study give a survey of TBT contamination levels found in the four areas. The paper discusses the importance of the pollution in comparison with other European coastal areas.

Journal Article↗
PubMed1993

Brainstem auditory evoked potentials. Differences related to physical activity.

Shorter sensory-motor reaction times have been reported in athletes compared with sedentary subjects. Previous results have shown significantly shorter visual evoked potentials (VEPs) latencies in a group of tennis players, but there was no difference between a group of rowers and control subjects. In the present study, the same groups were investigated in order to establish whether similar differences could be found in relation to brainstem auditory evoked potentials (BAEPs). Waves I to V latencies (Ls), interpeak latencies (IPLs) and wave amplitudes were measured. The results showed great differences related to gender. The I-III IPL was shorter in the females than in the males. Differences were also found in relation to physical activity. The most important feature was the significantly shorter III-V IPL observed in the rowers and in the tennis players of both genders compared with sedentary control subjects. In the males these differences were linked to training factors. Therefore, unlike VEPs which seemed to be linked to sports requiring high visual acuity, BAEPs seemed to be linked more widely to top-class physical activity and not to specific sensory aptitude. It was hypothesized that the shorter III-V IPL might be due to shorter synaptic transmission time in the superior olivary complex.

Adolescent↗
PubMed1993

Myxoid change in decidualized scar endometriosis mimicking malignancy.

A case of cesarean scar endometriosis with massive decidualization is presented. The 25-year-old patient had an extensive, ulcerated lesion that mimicked malignancy microscopically due to myxoid change with alveolar patterns reminiscent of some soft tissue sarcomas, signet ring-like cells similar to mucin-producing carcinoma, and pseudoinfiltration of the fascia. The myxoid tissue was positive for acid mucopolysaccharides but negative with PAS. Decidual cells were vimentin positive and keratin negative. No atypia or mitoses were seen. The pseudoinfiltrative aspect was due to abundant extracellular matrix that separated the fascicles of the fascial tissue. There was a metaplastic decidual "proximity effect" in the surrounding, unaffected dermis, which may be responsible for the expansile features of the lesion. This case exemplifies the differential diagnosis of myxoid endometriosis with malignant conditions of the skin.

Abdomen↗
PubMed1993

A gene encoding arginyl-tRNA synthetase is located in the upstream region of the lysA gene in Brevibacterium lactofermentum: regulation of argS-lysA cluster expression by arginine.

The Brevibacterium lactofermentum argS gene, which encodes an arginyl-tRNA synthetase, was identified in the upstream region of the lysA gene. The cloned gene was sequenced; it encodes a 550-amino-acid protein with an M(r) of 59,797. The deduced amino acid sequence showed 28% identical and 49% similar residues when compared with the sequence of the Escherichia coli arginyl-tRNA synthetase. The B. lactofermentum enzyme showed the highly conserved motifs of class I aminoacyl-tRNA synthetases. Expression of the argS gene in B. lactofermentum and E. coli resulted in an increase in aminoacyl-tRNA synthetase activity, correlated with the presence in sodium dodecyl sulfate-polyacrylamide gels of a clear protein band that corresponds to this enzyme. One single transcript of about 3,000 nucleotides and corresponding to the B. lactofermentum argS-lysA operon was identified. The transcription of these genes is repressed by lysine and induced by arginine, showing an interesting pattern of biosynthetic interlock between the pathways of both amino acids in corynebacteria.

Amino Acid Sequence↗
PubMed1993

Influence of unilateral vocal fold fixation on the structure of the intrinsic laryngeal muscles.

Histomorphometric data (fiber frequencies, fiber diameters, and atrophy factors) were determined in laryngeal muscles [thyroarytenoid (VOC), posterior (PCA) and lateral (LCA) cricoarytenoids, and cricothyroid (CT) muscles]. Seventy-three muscles (43,700 fibers) from normal and carcinoma-infiltrated sides of the larynges of 11 patients were analyzed. The fiber diameters showed uniform values of 24.2 +/- 9.1 microns. Type-I fibers were more frequent in the PCA and less frequent in the LCA and the CT. In the VOC, the ratio was 1:1. The unilateral fixation of a vocal fold modified the structures of the LCA and the CT. The VOC and the PCA were not affected. A hypothesis based on the phonatory function of the CT is used to explain its atrophy.

Adenosine Triphosphatases↗
PubMed1993

Self-esteem in recovered bipolar and unipolar out-patients.

The hypothesis of a low self-esteem in depressive patients was tested using the Rosenberg Self-Esteem Scale in 24 recovered unipolar and 27 recovered bipolar patients, compared with a normal control group of 26 subjects matched for age and sex. The hypothesis was confirmed only for unipolars; bipolar patients presented a self-esteem score not significantly different from normal scores. Self-esteem was not related to clinical characteristics of the affective disorder, suggesting that low self-esteem may be a basic component of a depression-prone personality. The investigation of the relationship between self-esteem and social adjustment confirmed the presence of social conformism in bipolar patients and rigidly set low self-esteem in unipolar patients. These results should stimulate the evaluation of different psychotherapeutic treatments in the long-term psychosocial management of affectively ill patients.

Adult↗
PubMed1993

Primary culture of Reissner's membrane from the gerbil: growth, morphologic features, and characterization.

To overcome the technical difficulties encountered in investigating the physiology of Reissner's membrane (RM), primary culture of RM was established. Minute explants obtained by mechanical dissociation were seeded on impermeable substrate coated with collagen type I in serum-free, hormone-supplemented medium. Within 2 weeks, a large cultured area was obtained which reproduced the two cell layers of the original explant. One layer, deep or superficial depending on the side to which the explant adhered, was made of cells exhibiting light and electron microscopy characteristics of an epithelium. Immunohistochemical methods revealed that they expressed cytokeratin, demonstrating their epithelial nature. The second layer was made of mesenchymal cells. This study suggests that cell culture of RM will facilitate further investigation of its physiology.

Animals↗
PubMed1993

Protection by alpha-tocopherol against skin necrosis induced by doxorubicin hydrochloride.

Extravasation of doxorubicin hydrochloride during i.v. infusions can cause serious local complications due to the action of free radicals which are produced as a result of this leakage. An experiment was carried out using female Wistar rats to study the protective effect of alpha-tocopherol against the tissular necrosis produced by 0.05 mg of doxorubicin hydrochloride. alpha-Tocopherol was administered by two vehicles, one emulsified and the other gelled, with butylated hydroxytoluene and ascorbic acid used as antioxidants, respectively. No differences were observed in the diameters of the ulcers with each treatment in the various groups of animals relative to the control group. Conversely, differences were found (p < 0.05) in the period of chronic lesion between the animals treated with alpha-tocopherol and those used as a control group, irrespective of the vehicle used. These results lead to the conclusion that accidental toxicity resulting from the leakage of doxorubicin hydrochloride in the skin can be mitigated by applying alpha-tocopherol topically, due to its regenerating action in the damaged cutaneous zones. This effect is independent of the vehicle used and also of the antioxidant employed in the elaboration of the formulas.

Animals↗
PubMed1993

[Contribution of cell culture to the study of cochlear endolymph].

Investigation of the mechanisms involved in the secretion of cochlear endolymph is hindered by the heterogeneity, the fragility, and the difficulty of access to the secretory structures of the inner ear, i.e. stria vascularis and Reissner's membrane. Cell culture may overcome these limitations and allow the study of the epithelial transport processes. Cultured cells derived from gerbil's explants of stria vascularis and Reissner's membrane presented morphological and immunohistochemical properties similar to those of the native cells. Investigation by the patch clamp technique of the apical membranes of marginal-like cells showed the presence of non specific cationic channels that could allow passive K+ flow towards endolymph and, thus, play a major role in the production of endolymph. Biochemical studies demonstrated that a cAMP production by these marginal-like cells. Primary culture of stria vascularis and Reissner's membrane is a suitable model to further investigate the physiology of endolymph production.

Animals↗
PubMed1993

[Dilated cardiomyopathy disclosing dermatopolymyositis. Management].

Cardiac involvement in dermatopolymyositis is common but rarely symptomatic. Cardiac failure as the presentation is very rare. No correlation exists between the severity of muscular involvement and cardiac involvement. Myocarditis is not uncommon and must be borne in mind if CK MB are above 3% of total CK. It is always associated with electrocardiographic abnormalities. Corticosteroids remain first line treatment. They generally lead to regression of cardiac problems which are usually of secondary importance. If cardiac involvement is severe, the spectacular action of venoglobulins should lead to their use being envisaged from the outset, combined with corticosteroids.

Cardiomyopathy, Dilated↗
PubMed1992

Role of glycosylation on the secretion and biological activity of erythropoietin.

The erythropoietin (EPO) molecule contains four carbohydrate chains. Three contain N-linkages to asparagines at positions 24, 38, and 83, and one contains an O-linkage to a serine at position 126. We constructed human EPO variants that eliminated the three N-glycosylation sites by replacing the asparagines with glutamines singly or in combination. The O-linked carbohydrate chain was removed by replacing the serine with glutamine, valine, histidine, or alanine. A variant with a double mutation (Gln38,83) and another with a triple mutation (Gln24,38,83) were secreted poorly from COS1 and CHO cells even though RNA encoding these variants was present. All other variants with mutations in N-linked glycosylation sites were secreted normally. Removal of any of the N-glycosylation sites reduced the in vivo but not the in vitro biological activity of the EPO molecule. All the mutations at Ser126, the O-glycosylation site, were secreted normally. In vitro activity was also unaffected except for Ala126 which had a 50-fold decrease. The Val126 variant was tested in vivo, and its specific activity was only slightly less than that of the native EPO, which indicates that the O-linked carbohydrate is not essential for activity.

Animals↗