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Biomedical subjects

L Villa

Publications and source records attributed to L Villa.

At least 109 records · Page 6Linked to original sources
PubMed1985

Cellular immunity against Salmonella typhi after live oral vaccine.

Seventeen adult volunteers were vaccinated orally with the live attenuated Salmonella typhi mutant strain Ty21a. Their peripheral blood mononuclear cells were tested at different times after vaccination for direct cell-mediated activity against bacteria, employing a simple short-term in vitro assay. It was observed that 16/17 of the vaccinated subjects acquired the capacity to express specific cellular immunity against S. typhi which lasted from 15 days to at least 3 years. The effector cell of the in vitro antibacterial activity was preliminarily characterized as a non-adherent T3+, T8-, T4+ lymphocyte. In parallel, mice immunized orally with S. typhimurium and proving resistant to reinfection were tested employing the same in vitro assay. Also in this case peripheral and, most important, intestinal lymphocytes were able to express cellular immunity against the agent of murine typhoid. It is concluded that administration of live oral vaccine against S. typhi results in the induction of specific cellular immunity which is expressed at the peripheral and, probably, also at the intestinal level.

Adult↗
PubMed1985

In vitro generated mast cells express natural cytotoxicity against tumour cells.

Bone marrow cells from mice were cultured in vitro in the presence of interleukin-3 (IL-3). After 2 weeks, the majority of the cells differentiated towards mast cells as judged by morphological and biochemical criteria. When populations of 99% IL-3-dependent mast cells (IL-3 MC) were tested for their anti-tumour activity in vitro, it was found that they can express natural cytotoxicity (NC) but not other natural reactivities. Moreover, the effector cells were not positive for Thy 1, Lyt 1 and Lyt 2 markers. The capability of mast cells to express NC activity seems to be related to their in vitro differentiation, since mast cell deficient W/Wv mice had normal NC activity. Thus, IL-3 MC must be added to the variety of cells capable of expressing natural anti-tumour reactivities in vitro.

Animals↗
PubMed1985

Natural anti-bacterial activity against Salmonella typhi by human T4+ lymphocytes armed with IgA antibodies.

Peripheral blood mononuclear cells from normal volunteers possess natural anti-bacterial (NA) activity against S. typhi that can be measured in a 2-hr in vitro assay. Employing fractionation on nylon wool columns, Percoll gradients, plastic adherence, and E rosetting, the effector cell of NA activity appeared to be a lymphocyte of the T lineage rather than a macrophage, a B lymphocyte, or a large granular cell. Moreover, complement-dependent killing with monoclonal antibodies such as OKM1, OKB7, OKT8, 5.9 and the anti-natural killer cells AB8.28 did not reduce NA activity. On the contrary, this was completely inhibited when OKT3, OKT11, or OKT4 antibodies and complement were used to pretreat the effector lymphocytes. Indeed, T4+ cells sorted with a FACS displayed an extremely high NA activity against S. typhi. By pretreatment of peripheral lymphocytes with F(ab')2 fragments against human IgA, the NA activity was blocked. It is therefore suggested that NA activity by human cells might be a mechanism of defense against infections, acting as antibody-dependent cellular cytotoxicity expressed by T4+ lymphocytes coated with preexisting anti-Salmonella IgA antibodies.

Antibodies, Bacterial↗
PubMed1985

[Esculin hydrolysis, a confirmation test for fecal streptococci detected on Slanetz-Bartley medium].

Samples of marine waters have been analyzed for recovering faecal streptococci applying the membrane filtration technique on Slanatez-Bartley medium. It has been pointed out that this medium can yield high proportions of non-group D streptococci: in fact its selectivity seems to be rather low at least for certain samples. This study aims to test and to overcome the disadvantage of the high counts of faecal streptococci due to background microrganisms. The hydrolysis of esculin may be used as a confirmatory test for increasing the selectivity. Membranes showing high numbers of streptococci-like colonies have been transferred from Slanetz-Bartley (MEA) medium to an esculin iron agar (EIA) plate. After 20 min at 41 degrees C small black spots appeared on the backside of the membrane where the colonies had hydrolyzed esculin were resident. The number of positive colonies may be recorded as the real number of faecal streptococci.

Esculin↗
PubMed1984

IgA-dependent cell-mediated activity against enteropathogenic bacteria: distribution, specificity, and characterization of the effector cells.

Antibody-dependent cellular cytotoxicity (ADCC) against murine enteropathogenic bacteria such as Salmonella typhimurium and Salmonella tel aviv or Shigella X16 was assessed by using IgG, IgA, and secretory IgA (sIgA) in a 2-hr in vitro assay where peripheral and intestinal lymphocytes were used as effector cells. It was found that IgG could arm splenocytes (SpL) better than IgA. However, IgG did not arm lymphocytes from Peyer's patches (PPL) or from mesenteric lymph nodes (MnL), whereas IgA of plasmacytoma origin against S. tel aviv and purified intestinal sIgA against Shigella X16 induced specific antibacterial ADCC with both SpL and PPL. When sIgA were tested with intestinal lymphocytes from the epithelium and the lamina propria, i.e., cells from the gut mucosa which first interact with enteric bacteria, it was found that both these lymphoid populations were able to express sIgA-dependent ADCC against Shigella X16. In parallel tests, cells from thymus and popliteal lymph nodes failed to express ADCC. Blocking studies with purified IgG and IgA of goat, rabbit, and mouse origin demonstrated that the Fc-alpha and Fc-gamma receptors were specifically involved in IgA- or IgG-dependent antibacterial ADCC. At least two effector populations, a macrophage and a Thy-1.2- lymphocyte, were observed to exert IgA-ADCC at the splenic level, whereas only lymphoid cells expressed this activity at the GALT level. Together, these results describe a new activity of IgA against enteropathogenic bacteria.

Animals↗
PubMed1984

Genetic control of in vitro natural cell-mediated activity against Salmonella typhimurium by intestinal and splenic lymphoid cells in mice.

In vitro natural anti-bacterial activity against Salmonella typhimurium by lymphocytes from Peyer's patches and spleens was assessed in several mouse strains. C3H/HeN and CBA/J mice, which are resistant to S. typhimurium infections, showed a natural anti-bacterial activity significantly higher than BALB/c, C57BL/10, C57BL/6 and C3H/HeJ mice, i.e. strains susceptible to the in vivo bacterial infection. In these susceptible strains and also in A/J mice, a significantly higher natural activity was observed in females compared to males. The sex control of natural anti-bacterial activity was further stressed by the fact that orchidectomy could induce a strong activity in low responder C57BL/10 male mice. With the exception of Beige mice, a low natural killer (NK) strain also with no natural activity against S. typhimurium in both sexes, the genetic distribution of natural anti-bacterial activity was extremely different from that of the NK activity. Thus, these results further stress the difference between natural anti-bacterial activity and NK cytotoxicity. Furthermore, our data establish a possible link, although with some exceptions, between in vivo susceptibility to S. typhimurium infections and in vitro natural activity against these bacteria.

Animals↗
PubMed1984

QSAR in a series of muscarinic agents. Note V. New sets of rigid and flexible ligands.

A deeper insight of muscarinic receptor attachment points is obtained on studying new sets of rigid and flexible ligands. The quantitative analysis of the correspondence between biological response and structural ligand features confirms that pD2 values are strongly dependent on hydrophobic and steric parameters. Moreover, it is shown that receptor attachment points are interrelated and their simultaneous perturbations contribute to enhance the activity with comparable effectiveness.

Animals↗
PubMed1983

Natural and antibody-dependent cell-mediated activity against Salmonella typhimurium by peripheral and intestinal lymphoid cells in mice.

Cell-mediated immune responses were assessed employing a 2-hr in vitro cytotoxicity assay against S. typhimurium. It was observed that lymphocytes from GALT as well as from peripheral lymphoid organs possessed natural antibacterial activity, whereas macrophages were devoid of this spontaneous activity. The distribution of this newly described natural activity was PPL greater than MnL greater than IEL = SpL = PBL greater than PoL; this did not correlate with the organ distribution of NK activity against YAC-1 tumor cells, which was PBL greater than SpL = IEL greater than MnL = PoL = PPL. Moreover, the phenotype of the splenic effector cell of the natural activity against S. typhimurium showed some differences from that of NK activity. In fact, both these cells were asialo GM1+, Fc-receptor+, nonadherent, and nonphagocytic, but the former was Thy-1.2- and the latter Thy-1.2+. The effector cell of the natural antibacterial activity in the Peyer's patches had the same phenotype as the splenic one. It was then observed that the antibacterial activity could be augmented by the addition of immune antibodies against S. typhimurium. This was particularly evident employing IEL, SpL, and PBL as effector cells, whereas PPL and MnL did not show any antibody-dependent antibacterial activity. Furthermore, these last two populations could not mediate ADCC against CRBC. Employing selective methods to deplete cell populations, we observed that, at least at the splenic level, there is also a cell that differs in its phenotypic characteristics from that mediating natural antibacterial activity but that plays a role in the antibody-dependent reactions. In conclusion, these results suggest that natural and antibody-dependent antibacterial mechanisms might be important in defense against S. typhimurium, particularly at the gastrointestinal level, where many bacterial infections first take place and begin to interact with the host immune system.

Animals↗
PubMed1983

Interferon decreases production of hydrogen peroxide by macrophages: correlation with reduction of suppressive capacity and of anti-microbial activity.

Mouse peritoneal macrophages (M phi) expressed enhanced tumoricidal activity upon in vitro stimulation either with the lymphokine M phi-activating factor (MAF) or with fibroblast interferon (IFN-beta). In contrast, M phi suppressive activity on lymphoproliferation was not affected by MAF pretreatment, but was drastically reduced or abolished by IFN-beta. Catalase, the enzyme involved in the destruction of hydrogen peroxide (H2O2), did significantly decrease M phi suppressive capacity but had no effect on M phi tumoricidal activity. Analysis of the phagocytosis-dependent H2O2 production by IFN-beta-treated M phi demonstrated a strong impairment of the oxygen metabolite release, which strictly paralleled the decreased M phi suppressive capacity. On the other hand, MAF did not modify H2O2 release by M phi. Studies on M phi antibacterial activity against Salmonella typhimurium, a function thought to depend upon H2O2 production, showed that exposure of M phi to IFN-beta significantly impaired their bactericidal and bacteriostatic capacity, again in close correlation with the decrease in H2O2 production. Thus, IFN-beta appears as modulating both suppressive and antibacterial capacities of M phi through reduction of their oxygen metabolism, whereas regulation of M phi anti-tumour activity is possibly controlled by different mechanisms.

Animals↗
PubMed1982

QSAR in a series of muscarinic agents. Note IV. - New pyridine and furan derivatives.

Two new series of picolyl- and furfuryltrimethylammonium salts have been prepared and studied in order to support some hypotheses previously formulated in the study of the topology of the muscarinic receptor. The general picture of ligand interactions with receptor as seen with correlation analysis is discussed. The new quantitative structure-activity relationship is compared with those previously formulated and it is shown that biological data for new congeners are well predicted by a correlation equation published earlier.

Animals↗
PubMed1981

OSAR in a series of muscarinic agents. Note III--Alkyltrimethylammonium salts, ethers and esters of choline.

In the light of the experience gained studying various sets of muscarinic ligands related to a rigid model, flexible structures such as alkyltrimethylammonium salts, ethers and esters of choline have been prepared and their affinities (pD2) have been studied. The quantitative structure-activity relationships (QSAR) show that the pD2 value is strongly dependent on hydrophobic and steric parameters of the ligand substituent. Moreover, two indicator variables are considered to take ito account extra-activities connected with ligand special structural features. The overall QSAR confirm that the electrostatic attraction, the hydrophobic bonding and the polar interaction holding the ligand on the receptor are individually weak; however, these three forces collectively permit a more complete utilization of the receptor binding site.

Animals↗
PubMed1980

QSAR in a series of muscarinic agents. Note II - Pyridine and furan derivatives.

Two sets of substantial picolyl and furfuryltrimethylammonium salts have been synthesized and their affinities (expressed as pD2) have been studied with the aim of characterizing muscarinic receptor spaces to which the ligand structural features bind. The new data were combined with those relative to a set of substituted benzyltrimethylammonium salts previously studied to formulate an overall QSAR which showed that the pD2 value is strongly dependent on hydrophobic and steric parameters of the ring substituent. Moreover, two indicator variables were considered to take into account the extra-activity associated with special structural features of the heterocyclic system and the further increase in activity associated with a "cooperative interaction" between the lipophilic binding of the substituent and a polar interaction of the ring heteroatom. The results confirm our earlier predictions and offer a model for ligand binding which gives a consistent view of the topology of the ligand attachment points on the receptor.

Animals↗
PubMed1979

QSAR in a series of muscarinic agents.

The results of a pharmacological investigation on a series of 3-substituted benzyltrimethylammonium salts possessing muscarinic activity are reported. Correlative analysis shows that the pharmacodynamic activity is a function of the hydrophobic-lipophilic and steric parameters associated with the substituents. In particular, it is revealed that a lipophilic pocket of limited size is present in the muscarinic receptor at an optimal distance from the electron--rich site with which the cationic termination interacts.

Animals↗
PubMed1978

Comparison of prothrombin time and activated partial thromboplastin time on Dade Auto-FI and Bio-Quest Fibrometer.

Plasma assay results for prothrombin time and activated partial thromboplastin time obtained on the fully automated Dade Auto-FI were compared with those obtained on the more traditional semi-automated Bio-Quest Fibrometer. The precision data showed in a majority of cases the superior reproducibility of the Auto-FI over the fibrometer. However, we found that results of APTT utilizing both methodologies were not at present interchangeable.

Blood Coagulation Tests↗
PubMed1977

Biosynthetic and structural studies of hemoglobin in a patient with congenital dyserythropoietic anemia type I.

A 25 year old woman with congenital dyserythropoietic anemia (CDA) Type I is described. Typical morphologic abnormalities of the erythroid precursors in the bone marrow by light and electron microscopy, marked ineffective erythropoiesis and iron loading were present, Globin chain synthetic ratios as well as functional and structural studies on the patients hemoglobin were normal, ruling out the presence of thalassemia or a mutant hemoglobin which can both give rise to morphologic and clinical features similar to CDA. The laboratory findings on this patient and family members and a brief review of the literature are presented.

Adult↗