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Biomedical subjects

G Carra

Publications and source records attributed to G Carra.

32 records · Page 2Linked to original sources
PubMed1985

Trans-acting element(s) operating across species barriers positively regulate expression of major histocompatibility complex class II genes.

Raji, a human B lymphoma line, expresses high levels of major histocompatibility complex (MHC) class II antigens. Conversely, none of the detectable human Ia antigens is present in RJ 2.2.5, an immunoselected Raji variant. Clonal analysis, biochemical characterization, and nucleic acid hybridization studies of hybrids between mouse spleen cells and RJ 2.2.5 show that MHC class II gene expression is regulated in trans by a factor which, as judged by dominance studies, has the characteristics of an activator. Such a positive trans acting factor is expressed in mouse spleen cells, and is able to implement MHC class II gene expression across species boundaries. Expression of this factor in spleen cells strongly suggests that it plays a role in in vivo regulation of Ia expression. Additional data suggest that different subsets of class II genes such as DR and DQ may, in part, be regulated by different mechanisms. It has also been possible to show that the amount of In chain-specific mRNA, present at reduced levels in RJ 2.2.5 cells compared to the parental Raji cells, drastically increased in human X mouse cells hybrids reexpressing human Ia antigens, suggesting that the In chain gene and the class II genes, although located on different chromosomes, are regulated in a concerted fashion, either directly through the same implementing factor, or indirectly through a cascade mechanism.

Animals↗
PubMed1985

Reactivation by a trans-acting factor of human major histocompatibility complex Ia gene expression in interspecies hybrids between an Ia-negative human B-cell variant and an Ia-positive mouse B-cell lymphoma.

Raji, a human B-lymphoma cell line, expresses high levels of class II (Ia) antigens. The expression of Ia antigens is totally abolished at the level of specific mRNA accumulation in RJ 2.2.5, a variant cell line derived from Raji after mutagenesis and immunoselection. We report here that the human Ia antigen expression can be restored in interspecies somatic cell hybrids between RJ 2.2.5 cells and BALB/c-derived M12.4.1 (I-A+, I-E+) B-lymphoma cells. Two hybrid clones were studied in detail. In both clones Ia molecules of the DR and NG2 type were easily detected by cell surface immunofluorescence and specific immunoprecipitation. In contrast, the DQ1 molecules were not detected with the above technique. DNA hybridization experiments using specific probes indicated that alpha-chain DR and beta-chain DQ genes were present in the hybrids. However, RNA hybridization experiments revealed that beta-chain DQ mRNA was present in the hybrids at very low amount compared to alpha-chain DR-specific mRNA. These results indicate that at least several genes of the class II gene cluster are coordinately regulated by trans-acting factor(s) that operate across species barriers. The basis of the mechanisms controlling the expression of class II antigens in these human-mouse hybrids might be related to the extinction (lack of expression) or activation of tissue-specific traits that take place when genomes of cells of dissimilar developmental potentials are brought together.

Animals↗
PubMed1985

The human Ia-associated invariant chain is synthesized in Ia-negative B cell variants and is not expressed on the cell surface of both Ia-negative and Ia-positive parental cells.

The expression of Ia-associated human Invariant (In) chain glycoproteins was studied in the Raji B cells as well as in their RJ 2.2.5 Ia-negative derived variant cells by using a specific rabbit anti-human In chain antiserum. Two-dimensional gel electrophoresis of immunoprecipitates from either biosynthetically labeled or surface labeled cells were analyzed. In addition, flow microfluorometric analysis of stained cells was performed. The results indicate that the In chain is constitutively produced in the Ia-negative B cell variant. Moreover, it appears that several forms of In chain-related molecules, with different charges and distinct m.w. are equally expressed in Ia-positive and Ia-negative B cells. Finally, no evidence could be obtained that the In molecular family was expressed on the cell surface of Ia-positive Raji and Ia-negative RJ 2.2.5 cells.

Animals↗
PubMed1969

[Sleep and REM].

Explore the source record for details and available documents.

Electromyography↗
PubMedDate not supplied

Structural analysis of the CD69 early activation antigen by two monoclonal antibodies directed to different epitopes.

The biochemical structure of CD69 early activation antigen has been characterized by means of two newly isolated mAb, namely C1.18 and E16.5. Upon analysis by SDS-PAGE, C1.18-reactive molecules immunoprecipitated from 125I-surface labeled PMA activated PBL consisted of a 32 + 32 kD dimer, a 32 + 26 kD dimer, a 26 + 26 kD dimer and a 21 + 21 kD dimer. E16.5-reactive molecules consisted of a 26 + 26 kD dimer and a 21 + 21 kD dimer. Cross absorption experiments showed that E16.5 mAb reacts with an epitope of the CD69 molecule distinct from the one recognized by C1.18 mAb and present only on a subpopulation of the CD69 molecular pool. The patterns of migration of C1.18- and E16.5-reactive molecules in two-dimensional gel-electrophoresis, under reducing conditions before and after treatment with Endoglycosidase F enzyme suggest that the two mAb recognize the same glycoprotein structure, but in two distinct glycosylation forms, both expressed on the cell surface membrane. Finally, p32, p26 and p21 of CD69 complex obtained from three distinct normal donors did not show appreciable structural polymorphism, by two-dimensional peptide mapping, not only among single subunits within the same individual, but also among homologous subunits in distinct individuals. Further, it was found that CD69 complex is expressed at the cell surface of resting PBL, although at a very reduced level in comparison to PMA activated cells. C1.18 and E16.5 mAb induced comparable cell proliferation and IL-2 production in PBL in the presence of PMA. C1.18 mAb increased intracellular free calcium concn in PMA activated PBL after cross-linking with goat anti mouse Ig, while the effect induced by E16.5 mAb after cross-linking was consistently lower. Finally, it was found that Sepharose-linked C1.18 mAb, in the presence of rIL-2 or PMA, did not induce TNF release from 6 NK cell clones.

Antibodies, Monoclonal↗
PubMedDate not supplied

Human interleukin-2 promotes proliferation of activated B cells via surface receptors similar to those of activated T cells.

Human interleukin-2 (IL-2) is a glycoprotein of relative molecular mass (Mr) 15,000, which is released by T lymphocytes on stimulation with antigen or mitogen and functions as a T-cell growth factor (TCGF) by inducing proliferation of activated T cells. It is generally accepted that resting or activated B cells do not respond directly to IL-2 but require for their proliferation other T-cell-derived lymphokines usually referred to as B-cell growth factors (BCGFs). Recently, however, a monoclonal antibody reacting with the IL-2 receptor molecules expressed by activated T cells (anti-Tac) was shown to react also with certain B tumour cells; in addition, murine B cells proliferate in response to pure human IL-2. We now show that recombinant IL-2, derived from Escherichia coli expressing the human gene, is able to promote strong proliferation of human B cells activated with protein-A-rich Staphylococcus aureus Cowans strain I. Moreover, we demonstrate that the anti-Tac antibody also reacts with S. aureus-activated normal B cells and inhibits sharply the proliferative response of such cells to IL-2. Finally, immunoprecipitation experiments reveal that anti-Tac defines similar molecules on activated T and B cells.

Animals↗
PubMedDate not supplied

Mortality in the coke oven plant of Carrara, Italy.

A mortality study was undertaken on a cohort of 538 male workers employed at a coke plant in Carrara in the period 1960-1985. The follow-up period ranged from January 1 1960 to December 31 1990, with 10,665 person-years accumulated. A significant excess in mortality for lung cancer was observed: 19 observed deaths vs 10.02 expected deaths using national rates, SMR 190 (C.I. 95% = 114-296), and vs 11.19 expected deaths using regional rates, SMR 170 (C.I. 95% = 102-265). The results suggest the possible influence of this occupation on mortality from lung cancer, as was observed in previous studies performed on larger cohorts of coke oven workers.

Adult↗
PubMedDate not supplied

[Repetitive movement of the upper limbs: results of exposure evaluation and clinical investigation in cash register operators in supermarkets].

In order to evaluate the prevalence of joint and periarticular disorders of the upper limbs attributable to repetitive movements (WMSDs), 100 female supermarket cashiers were examined. Their average age was 29.5 years (SD = 6.3), and their average length of service was 3.9 years (SD = 1.9). Only 26% of the women were anamnestically negative for WMSDs, while 74% had one or more disorders due to repetitive trauma of the upper limbs, although a definite diagnosis could be made in only 33 cases. The majority of the disorders affected the right side and the localisation was primarily in the shoulder and wrist. The risk factor analysis on the one hand confirmed that high-frequency repetitive movements of the wrist and hand, associated with inadequate recovery times, do play a role in determining the onset of upper limb and carpal tunnel syndrome. On the other hand, the study also revealed a definite need to review the way the work is organised, so that each shift at the cash register includes suitable functional recovery periods.

Adult↗
PubMedDate not supplied

[Repetitive movement of the upper limbs: results of exposure evaluation and clinical investigation during jar packaging of preserved vegetables].

In order to assess the prevalence of work-related musculo-skeletal disorders of the upper limbs, a total population of 29 female workers in an industrial vegetable preserving plant were examined. The average age of the workers was 41.3 years (SD = 9.2), and their average length of service was 16.7 years (SD = 7.2). Only 20% of the workers were anamnestically negative, whilst 80% had one or more disorders attributable to repetitive trauma of the upper limbs. The disorders showed no prevalence for the right side, a finding in line with the risk analysis which indicated that both limbs were equally used. The results of the risk analysis and clinical assessment confirm that high-frequency actions, combined with improper posture and a shortage of suitable recovery times, play a causal role in determining the onset of the disorders studied.

Adult↗