GENETIC CONTROL OF THE ANTIBODY RESPONSE : I. DEMONSTRATION OF DETERMINANT-SPECIFIC DIFFERENCES IN RESPONSE TO SYNTHETIC POLYPEPTIDE ANTIGENS IN TWO STRAINS OF INBRED MICE

Immunization of CBA and C57 mice with a branched, multichain synthetic polypeptide, poly (tyr,glu)-poly DL-ala--poly lys, ((T,G)-A--L), in Freund's complete adjuvant results in a tenfold or more difference in the antigen-binding capacity of sera from the two strains, although they respond equally to bovine serum albumin. Immunization of CBA x C57 F1, F1 x CBA, and F1 x C57 mice reveals definite genetic control of the response to (T,G)-A--L, which appears to be due to a single major genetic factor, with perhaps one or more modifying factors. Immunization of CBA and C57 mice with (H,G)-A--L, a synthetic polypeptide in which histidine replaces tyrosine, gives the opposite result, CBA's respond and C57's do not. From this, it appears that the genetic control of the response to (T,G)-A--L is specific for the antigenic determinant. The implications of these results are discussed

ANTIBODY RESPONSE OF INBRED MOUSE STRAINS TO ORDERED TETRAPEPTIDES OF TYROSINE AND GLUTAMIC ACID ATTACHED TO MULTICHAIN POLYALANINE OR POLYPROLINE : TYR-TYR-GLU-GLU IS A MAJOR DETERMINANT OF THE RANDOM POLY-(TYR, GLU)-POLYDLALA--POLYLYS

Five inbred mouse strains which represent high and low responders to the random synthetic polypeptide poly(LTyr,LGlu)-polyDLAla--polyLLys, designated (T, G)-A--L, to which the immune response is controlled by an H-2-linked gene, were immunized with three ordered tetrapeptides composed of tyrosine and glutamic acid attached either to multichain poly-DL-alanine or to polyproline. Only one of the three antigenic determinants, namely tyrosyl-tyrosyl-glytamyl-glutamic acid (T-T-G-G), resembled the random peptide (T, G) in the pattern of immune responses elicited against it, and in the cross-reactivity of the specific antibodies with (T, G)-A--L. The immune response pattern to the other two ordered tetrapeptides, T-G-T-G and G-T-T-G, was different from that obtained with (T, G)-A--L, and no cross-reactivity was detected between the antibodies provoked with these peptides and (T, G)-A--L. Thus, it is suggested that T-T-G-G is a major determinant in the random (T, G)-A--L

Salmonella enterica Serovar Typhimurium 14028s Genomic Regions Required for Colonization of Lettuce Leaves.

Contamination of edible produce leaves with human bacterial pathogens has been associated with serious disease outbreaks and has become a major public health concern affecting all aspects of the market, from farmers to consumers. While pathogen populations residing on the surface of ready-to-eat produce can be potentially removed through thorough washing, there is no disinfection technology available that effectively eliminates internal bacterial populations. By screening 303 multi-gene deletion (MGD) mutants of Salmonella enterica serovar Typhimurium (STm) 14028s, we were able to identify ten genomic regions that play a role in opening the stomatal pore of lettuce leaves. The major metabolic functions of the deleted regions are associated with sensing the environment, bacterium movement, transport through the bacterial membrane, and biosynthesis of surface appendages. Interestingly, at 21 days post inoculation, seven of these mutants showed increased population titers inside the leaf, two mutants showed similar titers as the wild type bacterium, whereas one mutant with a large deletion that includes the Salmonella pathogenicity island 2 (SPI-2) showed significantly impaired persistence in the leaf apoplast. These findings suggest that not all the genomic regions required for initiation of leaf colonization (i.e., epiphytic behavior and tissue penetration) are essential for continuing bacterial survival as an endophyte. We also observed that mutants lacking either SPI-1 (Mut3) or SPI-2 (Mut9) induce callose deposition levels comparable to those of the wild type STm 14028s; therefore, these islands do not seem to affect this lettuce defense mechanism. However, the growth of Mut9, but not Mut3, was significantly impaired in the leaf apoplastic wash fluid (AWF) suggesting that the STm persistence in the apoplast may be linked to nutrient acquisition capabilities or overall bacterial fitness in this niche, which are dependent on the gene(s) deleted in the Mut9 strain. The genetic basis of STm colonization of leaves investigated in this study provides a foundation from which to develop mitigation tactics to enhance food safety

Boston's Back Bay : the urban framework and its visual organization

Thesis (M. Arch.)--Massachusetts Institute of Technology, Dept. of Architecture; and, (M.S.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1981.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH.Includes bibliographical references.by Michael Sela.M.Arch

Reflections on Palliative Care from the Jewish and Islamic Tradition

Spiritual care is a vital part of holistic patient care. Awareness of common patient beliefs will facilitate discussions about spirituality. Such conversations are inherently good for the patient, deepen the caring staff-patient-family relationship, and enhance understanding of how beliefs influence care decisions. All healthcare providers are likely to encounter Muslim patients, yet many lack basic knowledge of the Muslim faith and of the applications of Islamic teachings to palliative care. Similarly, some of the concepts underlying positive Jewish approaches to palliative care are not well known. We outline Jewish and Islamic attitudes toward suffering, treatment, and the end of life. We discuss our religions' approaches to treatments deemed unnecessary by medical staff, and consider some of the cultural reasons that patients and family members might object to palliative care, concluding with specific suggestions for the medical team

CONTRIBUTION OF DIFFERENT CELL TYPES TO THE GENETIC CONTROL OF IMMUNE RESPONSES AS A FUNCTION OF THE CHEMICAL NATURE OF THE POLYMERIC SIDE CHAINS (POLY-L-PROLYL AND POLY-DL-ALANYL) OF SYNTHETIC IMMUNOGENS

Genetic regulation of immunological responsiveness was studied at the cellular level by comparing the limiting dilutions of immunocompetent cells from spleen, thymus, and bone marrow of high and low responders as a function of the poly-L-prolyl and poly-DL-alanyl side chains of two synthetic polypeptide immunogens. The spleens of immunized and unimmunized high responder DBA/1 mice were found to contain respectively, 18- and 7-fold more limiting precursor cells specific for (Phe, G)-A--L than the spleens of SJL low responder donors. These results, using a synthetic polypeptide built on multichain poly-DL-alanine, confirm the findings reported for polypeptides built on multichain poly-L-proline (1, 2), that there is a direct correlation between immune response potential and the relative number of immunocompetent precursors stimulated. Cell cooperation between thymocytes and bone marrow cells was demonstrated for both (T, G)-Pro--L and (Phe, G)-A--L. Limiting dilutions of thymus and bone marrow cells in the presence of an excess amount of the complementary cell type indicated an eightfold lower number of detected (T, G)-Pro--L-specific precursors in DBA/1 (low responder) marrow when compared with SJL (high responder) marrow. No differences were observed in the frequency of relevant high and low responder thymocytes for the (T, G)-Pro--L immunogen. These results are similar to those reported for the (Phe, G)-Pro--L (3). In contrast to the cellular studies reported for the Pro--L series of immunogens, the marrow and thymus cell dilution experiments for (Phe, G)-A--L revealed genetically associated differences in both the marrow and thymus populations of immunocytes from high (DBA/1) and low (SJL) responders. In addition to a fivefold difference in limiting marrow cell precursors (similar to that seen in the Pro--L studies), a striking difference was observed between the helper cell activity of high responder DBA/1 and low responder SJL thymocytes. This difference was indicated by the observation that low responder thymocyte dilutions followed the predictions of the Poisson model, whereas dilutions of high responder thymocytes did not conform to Poisson statistics. Transfers of allogeneic thymus and marrow cell mixtures from DBA/1 and SJL donors confirmed the syngeneic dilution studies showing that the genetic defect of immune responsiveness to (Phe, G)-A--L is expressed at both the thymus and marrow immunocompetent cell level. The parameters presently known for genetic control of immune responses specific for (Phe, G) (Ir-1 gene) and for Pro--L (Ir-3 gene) have been compared. The Ir-1 and Ir-3 genes are not only distinct by genetic linkage tests (to H-2) (5, 6, 9), but they are also seen to be different by cellular studies. Furthermore, expression of low responsiveness within a given cell population was shown to depend on the chemical structure of the whole immunogenic macromolecule

CELLULAR BASIS OF THE GENETIC CONTROL OF IMMUNE RESPONSES TO SYNTHETIC POLYPEPTIDES : I. DIFFERENCES IN FREQUENCY OF SPLENIC PRECURSOR CELLS SPECIFIC FOR A SYNTHETIC POLYPEPTIDE DERIVED FROM MULTICHAIN POLYPROLINE ([T, G]-PRO--L) IN HIGH AND LOW RESPONDER INBRED MOUSE STRAINS

SJL mice are high responders to the synthetic multichain polypeptide antigen (T,G)-Pro--L, whereas DBA/1 mice are low responders (10, 11). In order to determine whether the genetic control of immune response can be correlated with the number of antigen-sensitive precursor cells, spleen cell suspensions from normal and immunized SJL and DBA/1 donor mice were transplanted into lethally X-irradiated syngeneic recipients (incapable of immune response) along with (T, G)-Pro--L. Anti-(T, G)-Pro--L responses (donor-derived) were assayed in the sera of the hosts 12–16 days later. By transplanting graded and limiting numbers of spleen cells, inocula were found which contained one or a few antigen-sensitive precursors reactive with the immunogen. Using this method to estimate the relative numbers of such cells for the high responder SJL strain, one precursor was detected in ∼1.3 x 106 and ∼7.2 x 106 spleen cells from immunized and normal donors, respectively. In contrast, one precursor was detected in about 30 x 106 spleen cells from low responder DBA/1 mice, irrespective of whether the donors had been immunized. These results indicate that the genetic control of immunity to the synthetic polypeptide antigen investigated is directly correlated to the relative number of precursor cells reactive with the immunogen in high and low responder strains