Protein kinase C and T cell function.
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Animals↗
Biomedical subjects
A Long
Publications and source records attributed to A Long.
Characterization of murine Flt4 ligand/VEGF-C.
Flt4 is a receptor protein tyrosine kinase that is expressed in the adult lymphatic endothelium and high endothelial venules. We have used a BIAcore assay to identify rodent and human cell conditioned media containing the ligand of Flt4 (Flt4-L). Receptor-based affinity chromatography was used to purify this growth factor, followed by amino acid sequencing and molecular cloning of the murine cDNA, the orthologue of human vascular endothelial growth factor-C and vascular endothelial growth factor related protein. The murine flt4-L gene was localized to chromosome 8 and demonstrated to be widely expressed. Flt4-L was found to have a hydrophobic signal sequence and a pro-peptide-like sequence that is removed to generate the mature N-terminus. In addition, the C-terminal region of Flt4-L has four repeats of a cysteine-rich motif that is presumably also proteolytically processed to generate the 21000 Mr polypeptide subunit of the Flt4-L homodimer. Recombinant Flt4-L activated Flt4 as judged by induction of tyrosyl phosphorylation, and induced mitogenesis in vitro of lymphatic endothelial cells.
Amino Acid Sequence↗
Vegetarians and vegans may be most at risk from low selenium intakes.
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Diet, Vegetarian↗
TNF-mediated cytotoxicity of L929 cells: role of staurosporine in enhancement of cytotoxicity and translocation of protein kinase C isozymes.
The role of protein kinase C (PKC) in tumour necrosis factor (TNF)-mediated cytotoxicity was investigated, using the L929 cell line. The PKC activator phorbol-12-myristate 13-acetate (PMA) increased proliferation and inhibited TNF-induced cytotoxicity of L929 cells. A range of specific PKC inhibitors had no effect on TNF-mediated killing, suggesting that PKC does not play a direct role in this response. However, staurosporine enhanced cytotoxicity by TNF in the presence of actinomycin D, a protein synthesis inhibitor. In view of this finding, the authors investigated the role of specific PKC isozymes in both TNF-mediated cytotoxicity and staurosporine-induced sensitization to killing. PKC-alpha, beta, epsilon and zeta were detected in L929 cells. PKC-beta was only weakly detected in the cytoplasm, PKC alpha, epsilon and zeta were all found in resting cytoplasm and membrane. Stimulation with PMA caused a strong translocation of PKC-alpha but not zeta to the membrane. TNF had no effect on these isozymes but interestingly caused a translocation of PKC-epsilon, which also occurred in response to PMA. Staurosporine caused a translocation of PKC-zeta to the plasma membrane and a loss of PKC-epsilon from the cytosol. Although TNF induced PKC-epsilon translocation, this is unlikely to be involved in cytotoxicity as this effect was also induced by PMA which protected against TNF-mediated cytotoxicity. Staurosporine also induced translocation of PKC-zeta, an isozyme whose activity was previously found to be resistant to inhibition by staurosporine. These findings suggest the possibility that the mechanism by which staurosporine potentiates TNF action does not involve inhibition of PKC, but in contrast may involve modulation of PKC-zeta.
1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
Protein kinase C isotypes theta, delta and eta in human lymphocytes: differential responses to signalling through the T-cell receptor and phorbol esters.
The repertoire of novel and atypical protein kinase C (PKC) isotypes present in human T cells and their subcellular localization have not been fully characterized. We detected calcium-independent PKC activity in whole cell fractions from unstimulated peripheral blood lymphocytes (PBL). Towards an understanding of the role of PKC isoforms in lymphocyte activation we have studied the expression of calcium-independent PKC isoforms theta, delta and eta in PBL. With isoformspecific antibodies we detected the presence of PKC theta and delta in whole cell fractions from unstimulated human PBL by Western blot analysis. In addition, immunocytochemical analysis confirmed the presence of the novel PKC isoform PKC eta in PBL. Using immunocytochemistry, PKC theta, delta and eta had distinct patterns of redistribution following activation by phorbol myristate acetate (PMA). However, signalling through the T-cell receptor (TCR) did not appear to induce such changes in isoenzyme redistribution. These findings indicate that activation of lymphocytes either through the TCR-CD3 complex or with PMA induces different signalling pathways with respect to calcium-independent isoenzymes. Signalling through receptors other than the CD3 complex may be involved in activation of these isotypes.
Blotting, Western↗
Subcellular localization and translocation of protein kinase C isoforms zeta and epsilon in human peripheral blood lymphocytes.
The calcium-independent members of the protein kinase C (PKC) family may play a significant role in T cell function. We have characterized the subcellular localization and redistribution of calcium-independent kinase C activity and of two specific members of this family (zeta and epsilon) in response to activation of human peripheral blood lymphocytes with phorbol myristate acetate (PMA) or through the TCR-CD3 complex. Both PMA and OKT3, an antibody against the TCR-associated CD3 complex, induce an increase in membrane and cytoskeletal activity with a concomitant decrease in cytosolic activity. By Western blot analysis, PKC epsilon is present in resting cytosol and membrane fractions, and is detected in the membrane following activation with PMA and in both the membrane and cytoskeleton following OKT3 activation. By contrast, PKC zeta is progressively lost from the cytoskeleton following activation with anti-CD3. Immunocytochemistry reveals distinct redistribution patterns for these enzymes in response to activation through anti-CD3 and by PMA. These findings demonstrate that signaling through the CD3 complex induces significant changes in calcium-independent PKC activity and in the intracellular distribution of specific isoenzymes, and support a role for specific functions for individual isoenzymes in T cell activation. Lastly, changes in the cytoskeletal distribution of these isoenzymes suggest a potential role in the modulation of cell structure in response to activation.
Biological Transport, Active↗
Nursing: a spiritual perspective.
This article explores and examines the fundamental need for nurses to include the promotion of the spiritual dimension of the health of human beings as well as the physical, mental and social facets if they truly wish to engage in holistic care. The author attempts to define the phenomenon of spirituality, aware of the dilemma that many individuals face when thinking and reflecting on this very personal and intangible issue. To be spiritual is to become fully human, the article argues, and the reverse is also true. Spirituality in health is inextricable in each person's search for the discovery of the truth about self and the meaning and purpose of life. Healthy communities are the product of healthy individuals who sow spiritual seeds such as unconditional positive regard, acceptance, respect and dignity for the benefit and advancement of individuals and humankind as a whole. The global nature of the phenomenon of spirituality is also shown by using examples of people who demonstrate compassion and communion with other human beings, in other countries in times of suffering, war and disaster. Compassion and empathy is expressed and experienced for victims of earthquakes that happen miles from home and far removed from personal or religious beliefs. Yet at such times we are all connected in the tapestry of life by our own human spirituality and earthiness. Abstract themes like compassion and justice are treated in the text within the context of spirituality. The author argues that being just and fair means that all patients have the right to achieve spiritual healing regardless of their belief systems, culture or creed. The works of some spiritual philosophers are used to reflect on this integral aspect of human caregiving. Historical symbols of spirituality are examined. The need for nurses to explore and reflect on the paradoxical concepts involved in their own spirituality is highlighted. Nurses are the essential providers of care and, therefore, the paper argues, guardians of that essential humanity that ensures that patients never become less than full human beings, whatever their condition, faith, culture or belief, or whoever they may be. The author contends that this responsibility is uniquely essential to being a nurse.
Attitude of Health Personnel↗
A role for CD9 molecules in T cell activation.
Costimulation mediated by the CD28 molecule plays an important role in optimal activation of T cells. However, CD28-deficient mice can mount effective T cell-dependent immune responses, suggesting the existence of other costimulatory systems. In a search for other costimulatory molecules on T cells, we have developed a monoclonal antibody (mAb) that can costimulate T cells in the absence of antigen-presenting cells (APC). The molecule recognized by this mAb, 9D3, was found to be expressed on almost all mature T cells and to be a protein of approximately 24 kD molecular mass. By expression cloning, this molecule was identified as CD9, 9D3 (anti-CD9) synergized with suboptimal doses of anti-CD3 mAb in inducing proliferation by virgin T cells. Costimulation was induced by independent ligation of CD3 and CD9, suggesting that colocalization of these two molecules is not required for T cell activation. The costimulation by anti-CD9 was as potent as that by anti-CD28. Moreover, anti-CD9 costimulated in a CD28-independent way because anti-CD9 equally costimulated T cells from the CD28-deficient as well as wild-type mice. Thus, these results indicate that CD9 serves as a molecule on T cells that can deliver a potent CD28-independent costimulatory signal.
Animals↗
Structural basis for the excision repair of alkylation-damaged DNA.
Base-excision DNA repair proteins that target alkylation damage act on a variety of seemingly dissimilar adducts, yet fail to recognize other closely related lesions. The 1.8 A crystal structure of the monofunctional DNA glycosylase AlkA (E. coli 3-methyladenine-DNA glycosylase II) reveals a large hydrophobic cleft unusually rich in aromatic residues. An Asp residue projecting into this cleft is essential for catalysis, and it governs binding specificity for mechanism-based inhibitors. We propose that AlkA recognizes electron-deficient methylated bases through pi-donor/acceptor interactions involving the electron-rich aromatic cleft. Remarkably, AlkA is similar in fold and active site location to the bifunctional glycosylase/lyase endonuclease III, suggesting the two may employ fundamentally related mechanisms for base excision.
Alkylation↗
pim-1 proto-oncogene expression in anti-CD3-mediated T cell activation is associated with protein kinase C activation and is independent of Raf-1.
We have studied pim-1 proto-oncogene expression in human T cell responses to Ag receptor-generated signals. The pim-1 gene encodes a serine/threonine protein kinase that is expressed primarily in cells of hematopoietic lineage and is implicated in the intracellular signaling processes accompanying lymphocyte activation. We show here that pim-1 mRNA expression is rapidly induced after receptor cross-linking with anti-CD3 Abs. We examined the linkage of pim-1 expression to known signaling pathways generated through the T cell Ag receptor. pim-1 mRNA was not substantially induced after elevation of intracellular free Ca2+. In contrast, PMA, which directly activates PKC, induced rapid pim-1 expression. Further, anti-CD3- or PMA-induced pim-1 expression was markedly reduced by various PKC inhibitors and by deficiency of the PKC epsilon isoform in a mutant T cell line. Thus, T cell Ag receptor-linked pim-1 expression appears to be coupled to the PKC component of transmembrane signaling. Because the activation of protein kinase C has been shown to activate Raf-1 kinase activity, the involvement of Raf-1 in pim-1 expression was also investigated using a human T cell line stably transfected with an inducible Raf expression vector. Although the overexpression of activated Raf was shown to cause a substantial increase in IL-2 expression, no discernible effects on pim-1 were apparent. In addition, we examined transcriptional and post-transcriptional mechanisms involved in PKC-mediated pim-1 expression and observed that both transcriptional and post-transcriptional mechanisms are coordinately involved in the up-regulation of the pim-1 proto-oncogene.
Calcium↗
Evidence-based decision making.
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Clinical Medicine↗
Predictive utility of the CSQ in low back pain: individual vs. composite measures.
Researchers have typically used factor-analytic composite measures of coping, instead of individual scales, to predict rehabilitation outcome. There are, however, both advantages and disadvantages to using individual or composite scores. This study extended the findings of Jensen et al. (1992), by prospectively comparing the individual and composite scores of the Coping Strategies Questionnaire (CSQ) in the prediction of 4 types of adjustment to low back pain. Two-hundred patients completed the CSQ, the Oswestry Index, the SCL-90R, and 4 lifting tasks at admission and discharge from a multidisciplinary pain clinic. Return to work was determined at 9-month follow-up. The CSQ scales were factor-analyzed to devise composite indices, and the 3 resultant factors were compared to the individual scales in the prediction of pain and other outcomes. The results indicated that the relative predictive utility of the composite or individual scales depended on which outcome measure was used to define adjustment.
Adaptation, Psychological↗
Patient awareness of the adverse effects of non-steroidal anti-inflammatory drugs (NSAIDs).
We set out to determine the extent to which two groups of patients reported having been informed about the adverse effects of NSAIDs. These consisted of 50 patients who had suffered an acute gastrointestinal bleed while taking a NSAID, and 100 age, sex and drug matched controls who had not. Eight (16%) of the index patients, and 41 (41%) of the control patients remembered having been informed of potential adverse effects, an odds ratio of 3.65 (95% CI 1.55-8.58, P < 0.002). Two (4%) of the index patients recalled having been advised what to do should adverse symptoms develop, whereas 21 (21%) of the control patients did so, an odds ratio of 6.38 (95% CI 1.4-28.4, P < 0.01). Eighteen (36%) of patients who bled had experienced gastrointestinal pain prior to the bleed, but of these only two (11%) admitted reduced compliance with NSAID therapy. In contrast, 10 (67%) of the 15 control patients who had suffered epigastric discomfort admitted reduced compliance, an odds ratio of 16.0 (95% CI 2.6-98.8, P < 0.001). Our results suggest that patients who report not having been informed of adverse effects of NSAIDs are less likely to reduce intake in response to epigastric pain than patients who report having received such information. If the patients who bled had reduced their intake of NSAIDs to the same extent as apparently better informed control patients in response to epigastric pain, it is possible that some episodes of acute gastrointestinal bleeding would have been avoided.
Adult↗
Effect of ageing upon warfarin dose requirements: a longitudinal study.
This longitudinal study was designed to establish the rate of age-related change in warfarin dose requirements. Warfarin dosage was recorded retrospectively in 104 patients who had been stabilized on warfarin for a median period of 10 years (range 6-24 years) for prophylaxis of thromboembolic disease. There was a significant negative correlation between dosage and age at the start of therapy (p = 0.002, r = -0.30). Warfarin requirements fell over time, dosage difference being significantly correlated with age difference (p = 0.01, r = 0.25). Use of regression equation derived from these data suggests a 21% fall in warfarin requirements in this population over a 15-year period. The relationship between change in warfarin dose requirements and ageing established in this longitudinal study is in good agreement with that established by cross-sectional studies, suggesting that no major birth cohort effect is influencing requirements in our warfarin-treated population.
Adult↗
An extended literature review of health professionals' perceptions of illicit drugs and their clients who use them.
The literature relating to health professionals and illicit drugs and clients who use them shows many common themes. It is evident that the majority of health professionals hold negative, stereotypical perceptions of illicit drug-users. Consequently, these negative attitudes become prejudicial, hence blocking the professional from carrying out effective and humane nursing care to this client group. Evidence also shows that health professionals' perceptions on the legalization of currently illicit drugs is linked to their own use of these drugs rather than any social or health reasons. Professionals' views on the different illicit substances are also coloured by their use, not by the actual evidence relating to the effects of that drug, in particular, cannabis. The literature shows that health professionals project heavily on to the client all their own negative perceptions of illicit drug use, in the care setting. This has produced very unsatisfactory and unsafe care, resulting in both client and carer being dissatisfied with the whole aspect of care. In addition, specialist teams are being swamped by health professionals who are referring almost every illicit drug-user to these services. The future may be brighter with the generalist and specialist working closely together for the benefit of all, especially the client and, ultimately, the community.
Attitude of Health Personnel↗
An exploration of nurses' attitudes to the nursing care of the suicidal patient in an acute psychiatric ward.
Suicidal patients admitted to hospital following a suicidal attempt or expressing suicidal ideation present a real challenge to health professionals with regard to their therapeutic care. This study was undertaken to explore the attitudes of psychiatric nurses caring for such patients. Results reveal that psychiatric nurses do hold positive views on caring for potentially suicidal patients, contradicting previous studies where more negative feeling were expressed by nurses, especially those with initial contact. Findings also show that some nurses experience an element of distress, and the length of experience within such a working environment does not affect the nurses' level of satisfaction gained on caring for the suicidal patient. This study also identifies an expression of need for further education and practice in interpersonal skills and therapeutic modalities to enhance and develop a more effective delivery of care for this group of patients.
Adolescent↗
Expression of CD44 and its variants on gastric epithelial cells of patients with Helicobacter pylori colonisation.
BACKGROUND: Studies have suggested that expression of the adhesion molecule CD44 may be of prognostic importance in gastric cancer. In addition, there is strong evidence that Helicobacter pylori has a role in gastric cancer. AIMS: To determine the expression of CD44 and its variants (v6, v9) and HLA class II molecules on human gastric epithelial cell and intraepithelial lymphocytes in patients with and without H pylori infection. PATIENTS: Eighteen patients (seven men and 11 women) attending for endoscopic evaluation because of upper gastrointestinal symptoms were included. An additional 10 patients (five men and five women) were analysed for CD44 variant expression). METHODS: Biopsy specimens were taken from the gastric antrum during endoscopy. Gastric epithelial cells and intraepithelial lymphocytes were examined by two colour flow cytometry and compared in patients with and without H pylori infection. RESULTS: Expression of CD44 and its variants (CD44 v9) was increased in epithelial cells but not in intraepithelial lymphocytes. Both epithelial cells and intraepithelial lymphocytes expressed higher levels of HLA class II molecules (DR and DP), possibly as a result of local cytokine production. Furthermore, results showed upregulation of CD44 on a gastric epithelial cell line (AGS) by cytokines and peripheral blood mononuclear cell supernatant. CONCLUSIONS: These data suggest that H pylori, either directly or through a local inflammatory response, is responsible for increased expression of CD44 and its variant CD44 v9. These data are of potential importance in relation to increased expression of CD44 and CD44 v9 on gastric carcinoma.
Adult↗
HIV risk behavior, street outreach, and condom use in eight high-risk populations.
In this paper we examine risk behavior, exposure to street outreach, and condom use in samples of injecting drug users (IDUs) and high-risk youth. We used systematic sampling methods to produce representative samples of injecting drug users IDUs (five sites) and high-risk youth (three sites). The populations surveyed engaged in high levels of sexual risk behavior: 20% to 46% reported two or more sex partners in the last month. The majority (62% to 97%) knew someone infected with HIV. Condom use rates approached national health promotion goals for nonsteady partners but not for steady or main partners. Having a condom at time of interview was the most consistent predictor of condom use at last intercourse. Many of the respondents have been in contact with street outreach programs and many acknowledged some personal risk for HIV infection. However, most of the injecting drug users and high-risk youth interviewed (and their sex partners) were still at risk through unprotected sex.
Adolescent↗