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N Abraham

Publications and source records attributed to N Abraham.

30 records · Page 2Linked to original sources
PubMed1991

Tyrosine phosphorylation of GAP and GAP-associated proteins in lymphoid and fibroblast cells expressing lck.

The Ras GTPase activating protein (GAP) is a strong candidate for the protein that links protein-tyrosine kinases to the Ras mitogenic pathway. GAP and two associated proteins, p62 and p190, were shown to be phosphorylated on tyrosine in the LSTRA thymoma cell line, in which the p56lck tyrosine kinase is overexpressed as a result of retroviral promoter insertion. In NIH3T3 fibroblasts expressing specific oncogenic and transformation-defective variants of p56lck, we found that the tyrosine phosphorylation of GAP complexes required both enzymatic activation and myristylation of p56lck, and correlated with lck transforming activity. The interaction between p62 and p190 from lck-transformed fibroblasts and GAP could be reconstituted in vitro using bacterial TrpE fusion proteins containing GAP Src homology 2 (SH2) domains. In vitro complex formation was insensitive to the prior denaturation of SH2 ligands, suggesting that SH2-binding sites are formed by linear peptide sequences. These results suggest that the tyrosine phosphorylation of GAP, and its interactions with SH2-binding proteins, may be involved in fibroblast transformation by activated lck, and may participate in signal transduction and cellular transformation in lymphoid cells.

Animals↗
PubMed1991

The lymphocyte-specific tyrosine protein kinase p56lck.

The CD4 and CD8 T cell surface antigens are physically associated with the tyrosine protein kinase p56lck. Accumulating data indicate that p56lck transduces intracellular tyrosine protein phosphorylation signals upon engagement of CD4 and CD8 by major histocompatibility complex (MHC) determinants expressed on antigen-presenting cells (APCs). Recent studies show that these p56lck-related phosphorylation events enhance T cell receptor (TCR)-mediated functions and are critical for the proposed co-receptor roles of CD4 and CD8. p56lck is also capable of enhancing antigen receptor responsiveness in the absence of CD4 or CD8 expression, suggesting that it can directly contribute to the TCR-induced tyrosine phosphorylation signal.

Amino Acid Sequence↗
PubMed1991

[Notes on the phantom. Supplements to Freud's metapsychology].

The author discusses secrets--phantoms--that are unconsciously passed on within a family from one generation to the next. They are experienced as foreign bodies and are not physically processed. A special technique is needed to decode them in the analytic process.

Family↗
PubMed1990

Activation of p56lck through mutation of a regulatory carboxy-terminal tyrosine residue requires intact sites of autophosphorylation and myristylation.

Mutation of the major site of in vivo tyrosine phosphorylation of p56lck (tyrosine 505) to a phenylalanine constitutively enhances the p56lck-associated tyrosine-specific protein kinase activity. The mutant polypeptide is extensively phosphorylated in vivo at the site of in vitro Lck autophosphorylation (tyrosine 394) and is capable of oncogenic transformation of rodent fibroblasts. These observations have suggested that phosphorylation at Tyr-505 down regulates the tyrosine protein kinase activity of p56lck. Herein we have attempted to examine whether other posttranslational modifications may be involved in regulation of the enzymatic function of p56lck. The results indicated that activation of p56lck by mutation of Tyr-505 was prevented by a tyrosine-to-phenylalanine substitution at position 394. Furthermore, activation of p56lck by mutation of the carboxy-terminal tyrosine residue was rendered less efficient by substituting an alanine residue for the amino-terminal glycine. This second mutation prevented p56lck myristylation and stable membrane association and was associated with decreased in vivo phosphorylation at Tyr-394. Taken together, these findings imply that lack of phosphorylation at Tyr-505 may be insufficient for enhancement of the p56lck-associated tyrosine protein kinase activity. Our data suggest that activation of p56lck may be dependent on phosphorylation at Tyr-394 and that this process may be facilitated by myristylation, membrane association, or both.

Animals↗
PubMed1990

A comprehensive approach to teaching management in a degree-completion dental hygiene program.

Changes in society have dictated changes in the future of the dental hygiene profession and in the curriculum used to prepare students. Dental hygiene students should be prepared to assume a variety of new roles in the oral health and health care fields, including administrator/manager, researcher, educator, clinician, patient advocate, and change agent. The role of the administrator/manager had been identified as an important one for dental hygienists. In order to develop the skills necessary to obtain a position in management or administration, dental hygiene students should have educational preparation in these areas. This paper describes the development of an enhanced business curriculum in a degree-completion program. The curriculum provides a basic foundation for the development of effective management skills and includes courses in business, human resources management, and marketing, along with elective course offerings and an externship program. An integrated approach to management is employed, with emphasis on application to oral health and health care delivery systems.

Administrative Personnel↗
PubMed1987

Prolonged apnoea with severe arterial hypoxaemia resulting from complex partial seizures.

Multi-channel tape-recordings of the EEG, breathing movements, arterial pulsed oxygen saturation and ECG were performed on a four-year-old child with a history of cyanotic episodes. These had started at nine months of age, resulted in cardiopulmonary resuscitation on unnumerable occasions, and were refractory to anti-epileptic medication. During each episode seizure activity appeared first, followed within a few seconds by sinus tachycardia, prolonged absence of inspiratory efforts and severe arterial hypoxaemia. As the seizure activity ended, breathing movements restarted and there was a gradual improvement in oxygenation.

Apnea↗