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Biomedical subjects

C Crain

Publications and source records attributed to C Crain.

12 recordsLinked to original sources
PubMed2001

1alpha,25-Dihydroxyvitamin d3 has a direct effect on naive CD4(+) T cells to enhance the development of Th2 cells.

1alpha,25-Dihydroxyvitamin D3 (vitD3) is an immunoregulatory hormone with beneficial effects on Th1 mediated autoimmune diseases. Although the inhibitory effects of vitD3 on macrophages and dendritic cells are well documented, any direct effects of vitD3 on Th cell development are not clearly defined. Using CD4(+)Mel14(+) T cells derived from mice on a BALB/c and a C57BL/6 genetic background we examined the effect of vitD3 on Th cell development. We demonstrated that vitD3 affects Th cell polarization by inhibiting Th1 (IFN-gamma production) and augmenting Th2 cell development (IL-4, IL-5, and IL-10 production). These effects were observed in cultures driven with splenic APC and Ag, as well as with anti-CD3 and anti-CD28 alone, indicating that CD4(+) cells can also be direct targets for vitD3. The enhanced Th2 development by vitD3 was found in both BALB/c and C57BL/6 mice. An increased expression of the Th2-specific transcription factors GATA-3 and c-maf correlated with the increased production of Th2 cytokines after vitD3 treatment. The vitD3-induced effects were largely mediated via IL-4, because neutralization of IL-4 almost completely abrogated the augmented Th2 cell development after vitD3 treatment. These findings suggest that vitD3 acts directly on Th cells and can, in the absence of APC, enhance the development of a Th2 phenotype and augment the expression of the transcription factors c-maf and GATA-3. Our findings suggest that the beneficial effects of vitD3 in autoimmune diseases and transplantation operate through prevention of strong Th1 responses via the action on the APC, while simultaneously directly acting on the T cell to enhance Th2 cell development.

Animals↗
PubMed2001

The use of inhaled prostacyclin in nitroprusside-resistant pulmonary artery hypertension.

Because nitroprusside NTP infusion used to differentiate between fixed and reversible pulmonary artery hypertension in heart transplant candidates can result in systemic hypotension before reducing pulmonary artery pressures, we observed the effect or inhaled prostacyclin (PGI(2)) on pulmonary artery pressures and transpulmonic gradient (TPG) in patients with NTP-resistant pulmonary artery hypertension. Six patients undergoing evaluation for orthotropic heart transplant (OHTX) with NTP-resistant pulmonary artery hypertension received inhaled PGI(2), with hemodynamic measurements made at baseline, on NTP- and PGI(2) inhaled after returning to baseline. Compared with hemodynamic results with NTP, inhaled PGI(2) caused significant decrease in pulmonary artery systotic pressure, 43.8 +/- 4.8 mm Hg vs 63.2 +/- 2.04 mm Hg (p < 0.001); Mean pulmonary artery pressure, 22.7 +/- 4.18 vs 32.3 +/- 3.39 mm Hg (p < 0.05); and TPG, 11.5 +/- 3.73 vs 17.0 +/- 4.69 mm Hg (p < 0.05), with a 40% decrease in pulmonary vascular resistance/systemic vascular resistance ratio. We conclude that inhaled PGI(2) has benefit in reversing pulmonary artery hypertension resistant to NTP, in patients undergoing OHTX evaluation which is due to its more selective pulmonary vasodilation.

Administration, Inhalation↗
PubMed2000

Cutting edge: ectopic expression of the IL-12 receptor-beta 2 in developing and committed Th2 cells does not affect the production of IL-4 or induce the production of IFN-gamma.

The IL-12 receptor-beta 2 (IL-12R beta 2) chain is expressed on Th1 cells and lost upon differentiation to the Th2 phenotype. This has been suggested as the basis for commitment of Th1 cells, because early differentiated Th2 cells do not reverse their phenotype and do not produce IFN-gamma on restimulation in the presence of IL-12. In this study, we ectopically expressed the IL-12 receptor-beta 2 (IL-12R beta 2) bicistronically with enhanced green fluorescent protein by retroviral infection in developing and committed Th2 cells. Restimulation of Th2 cells expressing this ectopic IL-12R beta 2 in the presence of IL-12 led to levels of IL-4 production similar to those in control Th2 cells. The expression of IL-12R beta 2 in Th2 cells did not lead to significant levels of IFN-gamma production, although IL-12-mediated STAT signaling and proliferation were restored. Thus, although the IL-12R beta 2 and IL-12-dependent STAT4 activation are required for Th1 responses, activation of this pathway is not sufficient to restore a Th1 phenotype in developing or committed Th2 cells.

Animals↗
PubMed2000

Evidence for evolutionarily conserved secondary structure in the H19 tumor suppressor RNA.

The molecular basis for function of the mammalian H19 as a tumor suppressor is poorly understood. Large, conserved open reading frames (ORFs) are absent from both the human and mouse cDNAs, suggesting that it may act as an RNA. Contradicting earlier reports, however, recent studies have shown that the H19 transcript exists in polysomal form and is likely translated. To distinguish between possible functional roles for the gene product, we have characterized the sequence requirements for H19-mediated in vitro suppression of tumor cell clonogenicity and analyzed the sequence of the gene cloned from a range of mammals. A cDNA version of the human gene, lacking the unusually short introns characteristic of imprinted genes, is as effective as a genomic copy in blocking anchorage-independent growth by G401 cells. The first 710 nucleotides of the gene can be deleted with no effect on in vitro activity. Further truncations from either the 5'- or 3'-end, however, cause a loss of suppression of clonogenicity. Using conserved sequences within the H19 gene as PCR primers, genomic DNA fragments were amplified from a range of mammalian species that span the functional domain defined by deletion analysis. Sequences from cat, lynx, elephant, gopher and orangutan complement the previous database of sequences from human, mouse, rat and rabbit. Hypothetical translation of the resulting sequences shows an absence of conserved ORFs of any size. Free energy and covariational analysis of the RNA sequences was used to identify potential helical pairings within the H19 transcript. A set of 16 helices are supported by covariation (i.e. conservation of base pairing potential in the absence of primary sequence conservation). The predicted RNA pairings consist largely of local hairpins but also include several long range interactions that bridge the 5'- and 3'-ends of the functional domain. Given the evolutionary conservation of structure at the RNA level and the absence of conservation at the protein level, we presume that the functional product of the H19 gene is a structured RNA.

Animals↗
PubMed2000

TGF-beta1 down-regulates Th2 development and results in decreased IL-4-induced STAT6 activation and GATA-3 expression.

TGF-beta plays an important role in immune regulation in vivo and affects T cell differentiation in vitro. Here we describe how TGF-beta modulates Th2 development in vitro and investigate its mechanisms of action. TGF-beta down-regulated Th2 development of naive CD4+ Mel-14high T cells derived from the DO11.10 ovalbumin-specific TCR-transgenic mouse, and this was observed both in cultures driven with anti-CD3 and anti-CD28 and with splenic APC and antigen. TGF-beta down-regulated GATA-3 expression in developing Th2 and these cells showed a diminished IL-4-induced STAT6 activation. We found, however, that naive cells driven in Th2 conditions with TGF-beta did not show a significantly decreased STAT6 activation, suggesting that TGF-beta inhibits Th2 development via a STAT6-independent mechanism.

Animals↗
PubMed1996

Using formative research to lay the foundation for community level HIV prevention efforts: an example from the AIDS Community Demonstration Projects.

The AIDS Community Demonstration Projects provided community-level HIV prevention interventions to historically hard-to-reach groups at high risk for HIV infection. The projects operated under a common research protocol which encompassed formative research, intervention delivery, process evaluation, and outcome evaluation. A formative research process specifically focusing on intervention development was devised to assist project staff in identifying, prioritizing, accessing, and understanding the intervention target groups. This process was central to the creation of interventions that were acceptable and unique to the target populations. Intended to be rapid, the process took 6 months to complete. Drawn from the disciplines of anthropology, community psychology, sociology, and public health, the formative research process followed distinct steps which included (a) defining the populations at high-risk for HIV; (b) gathering information about these populations through interviews with persons who were outside of, but who had contact with, the target groups (such as staff from the health department and alcohol and drug treatment facilities, as well as persons who interacted in an informal manner with the target groups, such as clerks in neighborhood grocery stores and bartenders); (c) interviewing people with access to the target populations (gatekeepers), and conducting observations in areas where these high-risk groups were reported to gather (from previous interviews); (d) interviewing members of these groups at high risk for HIV infection or transmission; and (e) systematically integrating information throughout the process. Semistructured interview schedules were used for all data collection in this process. This standardized systematic method yielded valuable information about the focal groups in each demonstration project site. The method, if adopted by others, would assist community intervention specialists in developing interventions that are culturally appropriate and meaningful to their respective target populations.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Risk behaviors and perceptions of AIDS among street injection drug users.

Standardized survey interviews (n = 325) and guided in-depth interviews (n = 22) were conducted with injection drug users (IDUs) in Long Beach, California, to document drug usage and injection patterns, sexual practices, perceived risk of HIV infection, sources of health information, and knowledge and attitudes about AIDS. Most IDUs reported sharing needles (87.9%), and a large minority reported regular sterilization of needles/syringes (40.3%). Lower rates of needle sharing were reported among cocaine users than among heroin and speedball users. HIV seroprevalence was 5.7 percent (11/194). Sexually active female (60.7%) and male (20.5%) IDUs reported exchanging sex for money or drugs. Overall, 48.3 percent of IDUs reported having made changes in their injection practices and one-third reported modifying their sexual behavior in order to avoid HIV infection. Differences in drug use, sexual practices, and drug treatment history were found with regard to gender, ethnicity, age, and type of drug injected. Implications of findings for the development of AIDS risk-reduction programs are presented.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Effects of cardiopulmonary bypass on pulmonary leukostasis and complement activation.

We measured white blood cell counts and complement component (C3a, C4a, and C5a) and prostacyclin levels, and studied lung biopsy specimens, in 16 patients undergoing cardiopulmonary bypass and compared them with four patients undergoing other pulmonary procedures. Bypass caused no significant elevation in peripheral venous white blood cell counts. Higher counts were present in the right atrium compared with the left atrium. Patients who underwent bypass had elevated complement component and prostacyclin concentrations before operation and these levels increased further during operation. Trapping of polymorphonuclear leukocytes occurred in pulmonary alveolar capillaries and venules after bypass. We conclude that bypass activates complement components primarily of the alternative pathway and leads to increased blood prostacyclin levels. These changes are accompanied by polymorphonuclear leukocyte accumulation in the lungs and may be important in initiation of the adult respiratory distress syndrome in these patients.

6-Ketoprostaglandin F1 alpha↗
PubMed1985

Topical antimicrobial toxicity.

Three topical antibiotics and four antiseptics (1% povidone-iodine, 0.25% acetic acid, 3% hydrogen peroxide, and 0.5% sodium hypochlorite) were directly applied to cultured human fibroblasts to quantitatively assess their cytotoxicity. The four antiseptics were found to be cytotoxic; all of the cytotoxic agents except hydrogen peroxide were subsequently found to adversely affect wound healing in an animal model. Comparison of bactericidal and cytotoxic effects of serial dilutions of these four topical agents indicated the cellular toxicity of hydrogen peroxide and acetic acid exceeded their bactericidal potency. Bactericidal noncytotoxic dilutions of povidone-iodine and sodium hypochlorite were identified. These experiments provide evidence that 1% povidone-iodine, 3% hydrogen peroxide, 0.5% sodium hypochlorite, and 0.25% acetic acid are unsuitable for use in wound care. This sequence of experiments could be used to identify bactericidal, noncytotoxic agents prior to their clinical use.

Acetates↗
PubMed1978

Arteriolar nephrosclerosis in the Syrian hamster.

Syrian hamsters developed spontaneous renal lesions that resembled those of arteriolar nephrosclerosis in man, and differed from other spontaneously occurring or virus-induced renal diseases in other rodent species. Morphologic changes were mainly degenerative with little cellular exudation and were associated with histologic changes in the intrarenal vasculature. The renal lesions were progressive, often fatal and sometimes were complicated by glomerular amyloidosis with the nephrotic syndrome and uremia. Endstage kidneys often had fibrinoid necrosis of intrarenal arterioles and thus resembled lesions characteristic of the malignant phase of human essential hypertension. Fibrinoid necrosis of small arterioles was common in the uterus, ovaries or testes of affected animals; it was less frequent in mesenteric or coronary vessels. Cardiac thrombosis, often involving the left atrium or left atrioventricular valves, also was common. Changes occurred earlier and often were more severe in females than in males. This disease was a major cause of morbidity and mortality and hampered life-span studies.

Animals↗