PubMed Health⌕ Search

Biomedical subjects

I Löwy

Publications and source records attributed to I Löwy.

At least 19 recordsLinked to original sources
PubMed1990

Medical Critique [Krytyka Lekarska]: a journal of medicine and philosophy-1897-1907.

Medico-philosophical reflections were developed in the 19th and the 20th centuries by three consecutive generations of Polish physicians, active in what was later named the Polish School of Philosophy of Medicine. The second generation of this school published its own journal, Medical Critique [Krytika Lekarska], from 1897 to 1907. Medical Critique included numerous articles on the nature of medical knowledge, the reductionism versus holism debate in biology and medicine, the importance of teleologically-oriented approaches in medicine, the influence of theories and of a priori ideas on clinical observations and on 'clinical facts', the problem of classification of diseases, the normative and ethical dimension of medicine, and the ion relationships between philosophy, history and medicine. The existence of a journal dealing specifically with theoretical reflections on medicine undoubtedly contributed to the propagation of original work in the philosophy of medicine in Poland.

Ethics, Medical↗
PubMed1985

Regulation of IgG1 and IgG2 subclass expression by adjuvant-activated splenic suppressor T cells.

Spleen cells from mice immunized with different adjuvants are able to suppress secondary in vitro IgG plaque-forming cell (PFC) responses. The suppressive effect is mediated by Lyt-2-positive T cells. IgG subclasses are affected differentially depending on the number of T suppressor (Ts) cells added in the assays. At low Ts cell concentration IgG2a and IgG2b PFC responses are selectively inhibited. At higher Ts cell concentration IgG1 responses could also be completely inhibited, but IgA and IgM responses are not affected. Suppressor cells responsible for IgG1, IgG2a, and IgG2b suppression are never found in the draining lymph nodes of adjuvant-immunized animals.

Adjuvants, Immunologic↗
PubMed1983

Isotype regulation of antibody production: T-cell hybrids can be selectively induced to produce IgG1 and IgG2 subclass-specific suppressive immunoglobulin-binding factors.

T2D4, a T-cell hybrid, spontaneously secretes suppressive immunoglobulin factor(s); when incubated with purified monoclonal mouse immunoglobulins, this hybrid produces high levels of immunoglobulin-binding factors specific for the subclass of the inducing immunoglobulin. Thus, we were able to induce the production of IgG1- or IgG2-specific inhibitory factors by the same T2D4 T-cell hybrid. These subclass-specific suppressive factors bind selectively to the IgG1 or IgG2 subclasses and inhibit specifically the secretion of antibodies of the corresponding subclass. Our results favor a model of negative regulation of isotype expression in which a given isotype triggers suppressor mechanism(s) specifically inhibiting its production.

Animals↗
PubMed1982

Characterization of suppressor cells regulating in vitro expression of IgG2A and IgG2B antibody responses.

In vitro cooperative responses between hapten-primed anti-Thy-1.2 plus C-treated spleen cells and carrier-primed T cells have different isotypic patterns depending on the source of the T helper cells. T helper cells from primed lymph node induce IgG1, IgG2a, and IgG2b PFC responses, whereas T helper cells from primed spleen induce only an IgG1 type of response. The addition of activated spleen cells to the lymph node cells suppresses their ability to generate IgG2a and IgG2b PFC responses. The suppressor cells involved have been characterized. Functionally, they appear as nonantigen specific and isotype specific, because they never reduce the IgG1 response. They are Lyt-2.2 positive, Lyt-1 negative, and radiosensitive. Their relative resistance to anti-Thy-1.2 plus C treatment indicates that they express low amounts of this antigen or that they are heterogeneous concerning the expression of Thy-1.2.

Animals↗
PubMed1981

Immune response potential to poly(Tyr,Glu)-poly(DLAla)--poly(Lys) of human T cells of different donors.

Human peripheral blood T cells of normal donors were activated in vitro with autologous adherent cells pulsed with poly(LTyr,LGlu)-poly(DLAla)--poly(LLys) [abbreviated (T,G)-A--L]. The "educated" T cells were tested: (i) for their ability to produce a (T,G)-A--L-specific T cell-replacing factor in the cooperation with B cells for antibody responses in vivo or in vitro and (ii) for their ability to proliferate in the presence of a second stimulus of (T,G)-A--L. Results of screening of 66 donors demonstrated that educated T cells of about 50% of the donors produced an active (T,G)-A--L-specific factor, whereas activated cells of only half of the factor producers were capable of proliferating in the presence of the antigen. Thus, as reported for all other species studied, human individuals differ in their response potential to (T,G)-A--L.

Antibody Formation↗
PubMed1980

T-cell hybridoma bearing heavy chain variable region determinants producing (T,G)-A--L-specific helper factor.

Thymus-derived lymphocytes (T cells) exert their regulatory effect (help or suppression) on the antibody production by B cells either by direct cell to cell interaction or by soluble mediators or factors. The low frequency of specific T cells, the heterogeneity of their responses and their relatively short life span have hampered the molecular characterization of the antigen recognition unit of T cells, and its structure is largely unknown. The lymphocyte hybridization technique, which has been found very useful for the production of B-cell hybridomas secreting specific monoclonal antibodies, has also been used for the generation of homogeneous and stable T-cell hybridomas with unlimited growth potential. So far the only specific effector function demonstrated in the established T hybridomas is the property to generate a factor(s) which suppresses antibody responses. We now describe the establishment of hybrid lines which exhibit characteristic T-cell markers. One of the hybridomas (denoted R-9) releases into the culture supernatant factor(s) with helper activity specific to the synthetic polypeptide (T,G)-A--L and bears surface determinants of the immunoglobulin heavy chain variable region (VH). Such hybrid cell lines are of great value for studies on the nature of the T-cell receptor.

Animals↗
PubMed1980

Induction of antibodies directed against self and altered-self determinants by a synthetic adjuvant, muramyl dipeptide and some of its derivatives.

In a serum free, 2-mercaptoethanol supplemented culture medium muramyl dipeptide (MDP) is able to increase the number of plaque-forming cells (PFC) directed against syngeneic, bromelain-treated red blood cells (br-MRBC) and against an autoantigen, mouse albumin. The non-specific stimulation of anti-br-MRBC PFC by MDP, as by bacterial lipopolysaccharide (LPS), can be observed in spleen cell populations depleted of adherent and phagocytic cells, and in nu/nu spleen cell cultures. However, the kinetics of the induction of anti-br-MRBC PFC in murine spleen cell cultures in presence of LPS or of MDP are not identical. Moreover, MDP is able to stimulate C3H/He Orl (LPS low-responder strain) cells. Thus, the mechanisms of non-specific stimulation by MDP or by LPS could be different. Experiments done with thirteen structural analogues of MDP showed that there exists a good correlation between the adjuvant activity and the ability to induce anti-br-MRBC PFC.

Acetylmuramyl-Alanyl-Isoglutamine↗