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Biomedical subjects

P Michetti

Publications and source records attributed to P Michetti.

At least 73 records · Page 4Linked to original sources
PubMed1992

Monoclonal secretory immunoglobulin A protects mice against oral challenge with the invasive pathogen Salmonella typhimurium.

Hybridomas producing monoclonal immunoglobulin A (IgA) antibodies against Salmonella typhimurium were generated by mucosal immunization of BALB/c mice with attenuated strains of S. typhimurium and subsequent fusion of Peyer's patch lymphoblasts with myeloma cells. To test the role of secretory IgA (sIgA) in protection against Salmonella sp., we analyzed in detail the protective capacity of a monoclonal IgA, Sal4, produced in polymeric as well as monomeric forms, that is directed against a carbohydrate epitope exposed on the surface of S. typhimurium. BALB/c mice bearing subcutaneous Sal4 hybridoma tumors and secreting monoclonal sIgA into their gastrointestinal tracts were protected against oral challenge with S. typhimurium. This protection was directly dependent on specific recognition by the monoclonal IgA, since mice secreting Sal4 IgA from hybridoma tumors were not protected against a fully virulent mutant that lacks the Sal4 epitope. Although monoclonal Sal4 IgA was present in the bloodstreams and tissues of tumor-bearing mice, it did not protect against intraperitoneal challenge and did not possess complement-fixing or bacteriocidal activity in vitro. Taken together, these results indicate that secretion of sIgA alone can prevent infection by an invasive enteric pathogen, presumably by immune exclusion at the mucosal surface.

Animals↗
PubMed1992

Return of esophageal peristalsis after nifedipine therapy in patients with idiopathic esophageal achalasia.

This study was carried out to demonstrate the possible return of esophageal peristalsis in patients affected by esophageal achalasia chronically treated with sublingual nifedipine and to investigate which parameters are correlated with the return of peristalsis. Thirty-two patients were treated with sublingual nifedipine 10-20 mg taken 30 min before meals. A clinical and manometric evaluation was performed before and after 6 months of therapy. Before treatment, in no patient was peristaltic activity recorded. After 6 months, peristalsis was observed in six patients. In this group, no pretreatment manometric parameter was different from that of the remaining achalasic patients; only the clinical history of dysphagia was significantly shorter (p < 0.001) and the esophageal diameter significantly less (p < 0.001). In conclusion, chronic treatment with sublingual nifedipine can induce a return of esophageal peristalsis in patients with a short clinical history of disease and slightly dilated esophagus.

Administration, Sublingual↗
PubMed1991

Prospective clinical and manometric study comparing pneumatic dilatation and sublingual nifedipine in the treatment of oesophageal achalasia.

A study was carried out in 30 patients affected by a mild or moderate degree of oesophageal achalasia to compare the clinical and manometric effects of sublingual nifedipine and pneumatic dilatation. Sixteen patients were dilated twice with Rider-Moeller dilators and 14 were treated with sublingual nifedipine 10-20 mg 30 minutes before meals. A manometric evaluation was performed before and six months after starting treatment. The clinical evaluation (according to Vantrappen's criteria) was performed every three months for a mean follow up of 21 months. In both groups of patients a significant (p less than 0.001) fall in lower oesophageal sphincter pressure was observed after treatment and excellent or good clinical results were observed in 75% of dilated patients and in 77% of patients treated with nifedipine. One patient could not tolerate nifedipine. No complications were observed after dilatation. It is concluded that longterm treatment with sublingual nifedipine and pneumatic dilatation are equally effective in the treatment of oesophageal achalasia of mild or moderate degree.

Administration, Sublingual↗
PubMed1991

Transepithelial transport of HIV-1 by intestinal M cells: a mechanism for transmission of AIDS.

This study was designed to determine whether human immunodeficiency virus type 1 (HIV-1) might enter the host by penetrating epithelial barriers through antigen-transporting M cells in lymphoid follicle-associated epithelia. Interaction of HIV-1 with epithelial cells was examined using mucosal explants from Peyer's patches of mice and rabbits. HIV-1 adhered to the luminal membranes of M cells of both species, and was endocytosed and delivered to intraepithelial spaces containing lymphocytes and macrophages. These observations suggest that M cells, which are numerous in the human rectal mucosa, may efficiently deliver HIV-1 to target cells in mucosal lymphoid tissue, and that such transport may contribute to sexual transmission of AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1989

[Practical consequences of ambulatory registration of blood pressure].

Ambulatory recorded blood pressure (BP) has been shown to correlate better with secondary target-organ damage than casual blood pressure, and has demonstrated that ambulatory BP cannot be predicted on the basis of casual BP measurements by the physician. To assess whether these recordings have practical repercussions on diagnosis and treatment, 182 patients (74 female/108 male) aged 16 to 84 years (mean 51.9 +/- 14.8 SD), all referred by their physicians to the investigation unit of the hospital, underwent ambulatory BP measurements using the portable Remler M2000 BP recorder. The mean systolic blood pressure was above 140 mm Hg in 96 patients (53%) and the mean diastolic blood pressure above 90 mm Hg in 81 (45%). -3 to 9 months later, multiple choice questionnaires were sent to the 34 physicians who had referred patients and had meanwhile received recording results without comments. The questions were designed ascertain the indication for BP recording in each patient and the changes undertaken in the light of the results. In 27% of the cases the assumed diagnosis was not confirmed and in 40.8% of the cases the planned or prescribed treatment was obviated or withdrawn. This percentage corresponds to the data previously published describing 30 to 40% of patients as hypertensive only in the physician's office. This latter percentage shows that ambulatory BP recordings contribute to the practical assessment of patients with mild to moderate elevation of office BP.

Adolescent↗
PubMed1989

Binding and transepithelial transport of immunoglobulins by intestinal M cells: demonstration using monoclonal IgA antibodies against enteric viral proteins.

M cells of intestinal epithelia overlying lymphoid follicles endocytose luminal macromolecules and microorganisms and deliver them to underlying lymphoid tissue. The effect of luminal secretory IgA antibodies on adherence and transepithelial transport of antigens and microorganisms by M cells is unknown. We have studied the interaction of monoclonal IgA antibodies directed against specific enteric viruses, or the hapten trinitrophenyl (TNP), with M cells. To produce monospecific IgA antibodies against mouse mammary tumor virus (MMTV) and reovirus type 1, Peyer's patch cells from mucosally immunized mice were fused with myeloma cells, generating hybridomas that secreted virus-specific IgA antibodies in monomeric and polymeric forms. One of two anti-MMTV IgA antibodies specifically bound the viral surface glycoprotein gp52, and 3 of 10 antireovirus IgA antibodies immunoprecipitated sigma 3 and mu lc surface proteins. 35S-labeled IgA antibodies injected intravenously into rats were recovered in bile as higher molecular weight species, suggesting that secretory component had been added on passage through the liver. Radiolabeled or colloidal gold-conjugated mouse IgA was injected into mouse, rat, and rabbit intestinal loops containing Peyer's patches. Light microscopic autoradiography and EM showed that all IgA antibodies (antivirus or anti-TNP) bound to M cell luminal membranes and were transported in vesicles across M cells. IgA-gold binding was inhibited by excess unlabeled IgA, indicating that binding was specific. IgG-gold also adhered to M cells and excess unlabeled IgG inhibited IgA-gold binding; thus binding was not isotype-specific. Immune complexes consisting of monoclonal anti-TNP IgA and TNP-ferritin adhered selectively to M cell membranes, while TNP-ferritin alone did not. These results suggest that selective adherence of luminal antibody to M cells may facilitate delivery of virus-antibody complexes to mucosal lymphoid tissue, enhancing subsequent secretory immune responses or facilitating viral invasion.

Animals↗