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Biomedical subjects

M De Luca

Publications and source records attributed to M De Luca.

At least 127 records · Page 7Linked to original sources
PubMed1991

[Study on the activity of a therapeutic bacterial combination in intestinal motility disorders in the aged].

The possible beneficial effects and changes in the histology of the duodenojejunal and colonic mucosa brought about by oral bacterial therapy were studied in 60 elderly patients (mean age +/- SD: 76.6 +/- 5.3 years) with bowel disorders mainly represented by diarrhea accompanied by abdominal pain and meteorism. All patients were submitted to a 7-day washout followed by treatment with 6 capsules daily, each capsule containing live, lyophilized Lactobacillus acidophilus (10(9) CFU/ml). The clinical course was observed in 50 patients while the remaining 10 were hospitalized and submitted to esophago-gastro-duodenoscopy and colonoscopy both before and after treatment for withdrawal of duodenal secretion and fragments of duodenojejunal and colonic mucosa biopsies. Duodenal secretion was examined bacteriologically, and after treatment an increase of the anaerobic flora at the expense of the aerobic one was found together with improved quality of the former. Histologic examination showed reduction of the inflammatory infiltration by lymphocytes and plasma cells and increased muciparous activity of the glands. Clinically, a marked improvement of the symptoms was observed in all 60 patients.

Age Factors↗
PubMed1991

Characterization of chloride and cation channels in cultured human keratinocytes.

Patch-clamp experiments on human cultured keratinocytes revealed the presence of three types of ion channel. The first type was a Cl(-)-selective channel, the current/voltage relationship of which showed outward rectification, the mean conductance at positive and negative membrane potentials being 66 pS and 16 pS respectively. The second type of channel showed almost equal permeability to alkali ions but was impermeable to Cl- and to the large organic cation N-methyl-D-glucamine. Its current/voltage relationship was linear with a mean unitary conductance of 18 pS in symmetrical 140 mmol/l NaCl. Finally, the third type was a large-conductance cation channel, which had in physiological ionic conditions a peculiar rectifying current/voltage relationship, the shape of which was strongly dependent on the concentration of divalent cations on both sides of the membrane. Lowering of Ca2+ and/or Mg2+ on either side of the patch led to a marked increase of the single-channel current. With identical solutions without Ca2+ Mg2+ on both sides of the patch the current/voltage relationship became ohmic and reached a conductance of 150-200 pS. In addition, channel activity was reversibly affected by changes of the external Ca2+ concentration. In particular, open-channel probability strongly increased at negative membrane potentials when the external Ca2+ was lowered from millimolar to micromolar values. Whole-cell experiments confirm the role of the extracellular Ca2+ as a modulator of the cation conductance.

Barium↗
PubMed1991

High expression levels of the "erythroid/brain" type glucose transporter (GLUT1) in the basal cells of human eye conjunctiva and oral mucosa reconstituted in culture.

The expression of the "erythroid/brain" type glucose transporter (GLUT1) seems to be a feature of "barrier" tissues, at least in humans. Recently, we reported that GLUT1 is highly expressed in the basal layers of either "authentic" human epidermis or human epidermis reconstituted in culture and that its expression seems to be related to keratinocyte differentiation. In this paper we demonstrate that GLUT1 is selectively expressed in the basal layers of either eye conjunctiva epithelia or oral mucosa, reconstituted in culture starting from 1-2 mm2 bioptic specimens of normal human tissue. GLUT1 mRNA and protein levels are very high in conjunctiva and oral mucosa, 2-3 times higher than in epidermis reconstituted in culture. Taking into account its localization at the border of tissues not directly vascularized, but metabolically active, GLUT1 could play an important role in controlling the entry of glucose into these firmly guarded tissues.

Blotting, Northern↗
PubMed1991

Polarized expression of integrin receptors (alpha 6 beta 4, alpha 2 beta 1, alpha 3 beta 1, and alpha v beta 5) and their relationship with the cytoskeleton and basement membrane matrix in cultured human keratinocytes.

In human keratinocytes cultured in conditions which allow differentiation and stratification and are suitable to reconstitute a fully functional epidermis, alpha 6 beta 4 and two members of the beta 1 integrin family (alpha 2 beta 1 and alpha 3 beta 1) were respectively polarized to the basal and lateral domains of the plasmamembrane both in growing colonies and in the reconstituted epidermis. Conversely, the alpha v integrin subunit, presumably in association with beta 5, was expressed at the basal surface in growing and migrating but not in stationary keratinocytes. The integrin alpha 6 beta 4: (a) was organized in typical patches which often showed a "leopard skin" pattern where spots corresponded to microfilament-free areas; (b) was not associated with focal contacts containing vinculin and talin but rather corresponded to relatively removed contact areas of the basal membrane as shown by interference reflection microscopy; and (c) was coherent to patches of laminin secreted and deposited underneath the ventral membrane of individual cells. The two beta 1 integrins (alpha 2 beta 1 and alpha 3 beta 1), both endowed with laminin receptor properties, were not associated with focal adhesions under experimental conditions allowing full epidermal maturation but matched the lateral position of vinculin (but not talin), cingulin, and desmoplakin, all makers of intercellular junctions. Often thin strips of laminin were observed in between the lateral aspects of individual basal keratinocytes. The integrin complex alpha v beta 5 had a topography similar to that of talin- and vinculin-containing focal adhesions mostly in the peripheral cells of expanding keratinocyte colonies and in coincidence with fibronectin strands. The discrete topography of beta 1 and beta 4 integrins has a functional role in the maintenance of the state of aggregation of cultured keratinocytes since lateral aggregation was impaired by antibodies to beta 1 whereas antibodies to beta 4 prevented cell-matrix adhesion (De Luca, M., R. N. Tamura, S. Kajiji, S. Bondanza, P. Rossino, R. Cancedda, P. C. Marchisio, and V. Quaranta. Proc. Natl. Acad. Sci. USA. 87:6888-6892). Moreover, the surface polarization of integrins followed attachment and depended both on the presence of Ca2+ in the medium and on the integrity of the cytoskeleton. We conclude that our in vitro functional tests and structural data suggest a correlation between the pattern of integrin expression on defined plasmamembrane domains and the mechanism of epidermal assembly.

Basement Membrane↗
PubMed1991

Acute venous thrombosis of spleno-mesenteric portal axis: an unusual localization of thromboembolism in the nephrotic syndrome.

The nephrotic syndrome has been frequently associated with thromboembolic episodes. We report the case of a patient affected by minimal change nephropathy who developed acute thrombosis of the spleno-mesenteric portal axis and partially recovered after thrombolytic and anticoagulant therapy. Unfortunately, the patient died of pulmonary embolism after suspension of the anticoagulant therapy for gastrointestinal bleeding.

Adult↗
PubMed1991

Kinetic profile of miocamycin in middle ear fluid and mucosa.

A group of 18 patients, before undergoing otoplastic surgery, was treated with miocamycin 600 mg in a single dose; middle ear tissue samples were collected at 2, 3, 4 and 6 h. A group of 20 patients suffering from secretory otitis media (SOM) was also treated with 600 mg of miocamycin in a single dose; collections of middle ear fluid (MEF) were performed at 1, 2, 4 and 6 h. Blood withdrawals from all patients occurred at the same time intervals. The miocamycin determination was performed by means of a microbiological method employing Sarcina lutea ATCC 9341. The highest serum levels (1.06 +/- 0.13 mg/l) were found at 2 h in the group from which middle ear mucosa had been withdrawn and at 1 h (2.2 +/- 0.5 mg/l) in the group from which the MEF had been collected; at 6 h miocamycin could be determined in both groups, with values ranging from 0.1 to 0.2 mg/l. In middle ear mucosa the miocamycin concentration was 1.52 +/- 0.27 mg/kg at 2 h and 0.2 +/- 0.09 mg/kg at 6 h. In MEF, the miocamycin concentration was 2.1 +/- 0.27 mg/l at 1 h and 0.24 +/- 0.05 mg/l at 6 h. The miocamycin concentration determined at 1 h in MEF was virtually equal to that in serum at the same time. At the following experimental times of withdrawal, the miocamycin concentration in mucosa specimens, as well as in MEF samples, proved to be markedly higher than values simultaneously found in serum.

Adult↗
PubMed1991

Cefixime shows good effects on group A and group B beta-haemolytic streptococci.

There is continued interest in the development of oral beta-lactam compounds, which can be used clinically to treat various bacterial infections, particularly those caused by beta-haemolytic streptococci. Cefixime is a new orally active cephalosporin, with a broad spectrum of antibacterial activity, including Enterobacteriaceae, Haemophilus influenzae, Branhamella catarrhalis, Streptococcus pneumoniae and Streptococcus pyogenes. Cefixime is highly resistant to hydrolysis by most beta-lactamases. In this study the authors examined the effects of this molecule on Group A and Group B beta-haemolytic streptococci, recently isolated from clinical specimens in the authors' laboratory. MICs and the growth curves of 36 strains of Group A streptococci and the effects of sub-MICs on buccal cell adhesion were evaluated. The results show that concerning the sub-MIC cefixime effect on streptococci adherence, the treatment led to a decrease in adherence to the cells of the strains studied. Moreover cefixime showed good activity with 86.1% of the strains with MIC less than or equal to 0.5 microgram/ml, and the growth curves demonstrated that the molecule possesses a bactericidal effect after 3 h. Concerning Group B streptococci, 70.3% of the strains showed a MIC less than or equal to 2 micrograms/ml. In conclusion cefixime demonstrates good activity on beta-haemolytic streptococci, particularly those of Group A.

Anti-Infective Agents, Urinary↗
PubMed1991

[Morphological characteristics of spreaders].

Different kinds of spreaders can be used in the lateral condensation technique. Selection of condensation instruments must not be empirical because the quality of the filling partly depends on the compatibility between the spreader and the prepared root canal. The shape of the instrument should allow for easy insertion to the proper length without any interference. On these bases the Authors evaluated and compared the morphology of some spreaders, and gave data and directions how to rationally use these instruments in clinical practice.

Dental Instruments↗
PubMed1991

Clinical and morphologic response to interdental brushing therapy.

The interdental papilla is the anatomic site most susceptible to periodontal disease. The gingival epithelium plays an important role as a barrier to protect the underlying connective tissue from exogenous noxious agents. A study was undertaken to evaluate the papillary epithelial response to reconstructive stresses conducted by gingival brushing (oral therapy) and scaling and root planing, intended to induce a keratinization associated with reduction or resolution of connective tissue inflammation. Results showed that patients who prolonged the interproximal hygiene practices for more than 30 minutes a day achieved a satisfactory keratinization of the papillary gingival epithelium.

Dental Plaque↗
PubMed1990

Structural and functional studies of integrin receptors in cultured human keratinocytes.

In human keratinocytes cultured in conditions which allow differentiation and stratification and which are suitable to reconstitute a fully functional epidermis, the integrin alpha 6 beta 4 and two members of the beta 1 integrin family (alpha 2 beta 1 and alpha 3 beta 1) were polarized to the basal and lateral domains of the plasma membrane both in growing colonies and in the reconstituted epidermis. Conversely, alpha v beta 5 integrin was expressed at the basal surface in growing and migrating but not in stationary keratinocytes. The integrin alpha 6 beta 4 was organized in patches and spots corresponding to F-actin-free submembraneous areas and did not colocalize to focal contacts; moreover, alpha 6 beta 4 colocalized with patches of laminin deposited underneath the ventral membrane of individual cells. The two beta 1 laminin receptor integrins (alpha 2 beta 1 and alpha 3 beta 1) were never found in the basal domain but matched the lateral position of vinculin (but not talin), cingulin and desmoplakins. Only the integrin complex alpha v beta 5 was associated with talin- and vinculin-containing focal adhesions mostly in the peripheral cells of expanding keratinocyte colonies and in coincidence with fibronectin strands. The topography of beta 1 and beta 4 integrins reflects a functional role in adhesion and in the maintenance of the state of aggregation of cultured keratinocytes since lateral aggregation was impaired by antibodies to beta 1 whereas antibodies to beta 4 prevented cell-matrix adhesion.

Calcium↗
PubMed1990

Polarized integrin mediates human keratinocyte adhesion to basal lamina.

Epithelial cell interactions with matrices are critical to tissue organization. Indirect immunofluorescence and immunoprecipitations of cell lysates prepared from stratified cultures of human epidermal cells showed that the major integrins expressed by keratinocytes are alpha E beta 4 (also called alpha 6 beta 4) and alpha 2 beta 1. The alpha E beta 4 integrin is localized at the surface of basal cells in contact with the basement membrane, whereas alpha 2 beta 1/alpha 3 beta 1 integrins are absent from the basal surface and are localized only on the lateral surface of basal and spinous keratinocytes. Anti-beta 4 antibodies potently inhibited keratinocyte adhesion to matrigel or purified laminin, whereas anti-beta 1 antibodies were ineffective. Only anti-beta 4 antibodies were able to detach established keratinocyte colonies. These data suggest that alpha E beta 4 mediates keratinocyte adhesion to basal lamina, whereas the beta 1 subfamily is involved in cell-cell adhesion of keratinocytes.

Animals↗
PubMed1990

In-vitro postantibiotic effects of miocamycin and erythromycin on gram-positive cocci.

The capability of miocamycin to induce a postantibiotic effect (PAE) on a Group A Streptococcus beta-haemolyticus clinical isolate and on Staphylococcus aureus ATCC 29213 has been studied. Erythromycin was chosen as a reference molecule. The exposure time to antibiotics was 90 min. The removal technique of the antibiotic agents consisted of a 1:200 dilution in cultural broth. Miocamycin displayed a PAE of 2 h 30 min in relation to the minimum inhibitory concentration (MIC) of Streptococcus and a PAE of 2 h 30 min in relation to the MIC of Staphylococcus. The PAE value lasting longer than the others was of 5 h 40 min towards Streptococcus and of 4 h 18 min towards Staphylococcus at a concentration eightfold the MIC. Erythromycin showed a PAE of 1 h 36 min in relation to the MIC of Streptococcus and a PAE of 1 h 30 min in relation to the MIC of Staphylococcus. The PAE value lasting longer than the others was of 3 h 15 min against Streptococcus and of 2 h 30 min against Staphylococcus at a concentration eightfold the MIC. In some cases a PAE was observed in relation to subinhibitory concentrations (1/2 MIC). Miocamycin therefore proved to possess a more evident capability to induce a PAE against the clinical isolate of Group A Streptococcus beta-haemolyticus and on Staphylococcus aureus ATCC 29213 than did erythromycin.

Adult↗