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At least 901 records · Page 50Linked to original sources
PubMed2002

Coexpression of ATP-binding cassette proteins ABCG5 and ABCG8 permits their transport to the apical surface.

Mutations in either ATP-binding cassette (ABC) G5 or ABCG8 cause sitosterolemia, an autosomal recessive disorder of sterol trafficking. To determine the site of action of ABCG5 and ABCG8, we expressed recombinant, epitope-tagged mouse ABCG5 and ABCG8 in cultured cells. Both ABCG5 and ABCG8 underwent N-linked glycosylation. When either protein was expressed individually in cells, the N-linked sugars remained sensitive to Endoglycosidase H (Endo H). When ABCG5 and ABCG8 were coexpressed, the attached sugars were Endo H-resistant and neuraminidase-sensitive, indicating that the proteins were transported to the trans-Golgi complex. The mature, glycosylated forms of ABCG5 and ABCG8 coimmunoprecipitated, consistent with heterodimerization of these two proteins. The Endo H-sensitive forms of ABCG5 and ABCG8 were confined to the endoplasmic reticulum (ER), whereas the mature forms were present in non-ER fractions in cultured hepatocytes. Immunoelectron microscopy revealed ABCG5 and ABCG8 on the plasma membrane of these cells. In polarized WIF-B cells, recombinant ABCG5 localized to the apical (canalicular) membrane when coexpressed with ABCG8, but not when expressed alone. To our knowledge this is the first direct demonstration that trafficking of an ABC half-transporter to the cell surface requires the presence of its dimerization partner.

ATP Binding Cassette Transporter, Subfamily G, Mem↗
PubMed2000

Pretreatment with DNA-damaging agents permits selective killing of checkpoint-deficient cells by microtubule-active drugs.

Cell-cycle checkpoint mechanisms, including the p53- and p21-dependent G(2) arrest that follows DNA damage, are often lost during tumorigenesis. We have exploited the ability of DNA-damaging drugs to elicit this checkpoint, and we show here that such treatment allows microtubule drugs, which cause cell death secondary to mitotic arrest, to kill checkpoint-deficient tumor cells while sparing checkpoint-competent cells. Low doses of the DNA-damaging drug doxorubicin cause predominantly G(2) arrest without killing HCT116 cells that harbor wt p53. Doxorubicin treatment prevented mitotic arrest, Bcl-2 phosphorylation, and cell death caused by paclitaxel, epothilones, and vinblastine. In contrast, doxorubicin enhanced cytotoxicity of FR901228, an agent that does not affect microtubules. Low doses of doxorubicin did not arrest p21-deficient clones of HCT116 cells and did not protect these cells from cytotoxicity caused by microtubule drugs, but cells in which p21 expression was restored enjoyed partial protection under these conditions. Moreover, in p53-deficient clones of HCT116 cells doxorubicin did not induce either p53 or p21 and provided no protection against paclitaxel-induced cytotoxicity. Therefore, (a) p53-dependent p21 induction caused by doxorubicin protects from microtubule drug-induced cytotoxicity, and (b) pretreatment with cytostatic doses of DNA-damaging drugs before treatment with microtubule drugs results in selective cytotoxicity to cancer cells with defective p53/p21-dependent checkpoint.

Antineoplastic Agents↗
PubMed1996

Does managed care permit appropriate use of psychotherapy?

The author reviews the history of the development of managed care, the restrictions it has placed on psychiatric treatments, including psychotherapy, and the concerns it has raised about access to and quality of care. He discusses research studies documenting that psychotherapy is a fundamental component of psychiatric treatment and that it must be included in all health plans and organized systems of care. Several false beliefs about the use and cost of psychotherapy are considered, such as that dyadic psychotherapy is based on abreaction, a technique that Freud abandoned, and that costs for psychotherapy will skyrocket if it becomes universally accessible. Research has indicated that inappropriate limitations on psychotherapy in prepaid settings lead to poor mental health outcomes. The author emphasizes that cost-based constraints on established psychiatric treatments are not acceptable until carefully constructed scientific outcome studies demonstrate that the use of such constraints does not lead to adverse consequences.

Health Care Costs↗
PubMed1989

No alcohol, but wine is permitted: a survey of obstetric units in Scotland.

Many health-care professionals have expressed increasing concern over the growing use of licit and illicit substances. Considerable interest has also been shown in the effects of substance use on the developing fetus. In view of both the media and academic coverage of this subject, the possible dangers to health of both mother and child should (presumably) be common knowledge. It would seem reasonable, therefore, to assume that screening women in the early ante-natal period for their use of tobacco, alcohol and other drugs would be routine practice. This survey attempted to obtain an overview of the approach of ante-natal clinics to substance use and, if possible, identify any areas of need which might exist. The responses obtained indicate that the approach taken by midwives and obstetricians was not uniform. A number of factors were identified as influencing service provision.

Alcohol Drinking↗
PubMed1986

A single-step silver enhancement method permitting rapid diagnosis of cytomegalovirus infection in formalin-fixed, paraffin-embedded tissue sections by in situ hybridization and immunoperoxidase detection.

A single-step silver enhancement method was developed which intensifies the polymerized nickel-complexed diaminobenzidine (Ni-DAB) reaction product of peroxidase. With such enhancement, an in situ hybridization procedure can be performed in less than 8 hr by using a 2-hr hybridization incubation and direct detection. Cytomegalovirus (CMV)-infected lung sections were hybridized in situ for 2 hr with a biotinylated CMV genomic-length probe. The probe was detected directly with avidin-biotinylated peroxidase using Ni-DAB as the substrate, and the reaction product was enhanced with silver. Silver was deposited only on the Ni-DAB and not on normally argyrophilic substances. Indirect detection of the probe using a sandwich technique before silver enhancement proved more sensitive, but the length of the procedure was increased without substantially changing the result (infection vs. no infection). Sensitivity was also improved by omitting the dehydration step before applying the probe, and by increasing the temperature and duration of denaturation. In a blinded study of 21 open-lung biopsies, 13 of 13 culture-negative specimens were negative by hybridization, and 7 of 8 culture-positive specimens were positive by hybridization. Modified short hybridization with a biotinylated probe and silver-enhanced direct detection therefore provides a rapid but sensitive method for diagnosis of viral infection.

3,3'-Diaminobenzidine↗
PubMed1986

Microimmunoassay permits determination of concentrations in immunohistochemistry controls.

A competition enzyme-linked immunosorbant assay (CELIA) can be used to determine the amount of antigen needed to immunoabsorb an antiserum. This is demonstrated using both polyclonal and monoclonal antibodies against human amylase. This method is of especial value when the tissue is particularly difficult to obtain, and especially valuable when CELIA has already been completed.

Amylases↗
PubMed2002

Constitutive exclusion of Csk from Hck-positive membrane microdomains permits Src kinase-dependent proliferation of Theileria-transformed B lymphocytes.

Infection of bovine T cells and B cells with the intracellular protozoan parasite Theileria parva induces a transformed phenotype with characteristics comparable to leukemic cells. The transformed phenotype reverts on drug-induced parasite death, and the cured lymphocytes acquire a resting phenotype and eventually die by apoptosis if not further stimulated. Here, we show that both lymphocyte proliferation and activation of the transcription factor AP-1 are mediated by Src-family protein tyrosine kinases (PTKs) in a parasite-dependent fashion. Src-family PTKs are known to be present in glycolipid-enriched microdomains (GEMs), also called lipid rafts, and to be negatively regulated by PTK Csk complexed to tyrosine-phosphorylated transmembrane adapter protein PAG (phosphoprotein associated with GEMs) also called Cbp (Csk-binding protein). We, therefore, purified GEMs from proliferating infected B cells and from growth-arrested cells that had been drug-cured of parasites. Proliferation arrest led to a striking increase of PAG/Cbp expression; correspondingly, the amount of Csk associated with PAG/Cbp in GEMs increased markedly, whereas PTK Hck accumulation in GEM fractions did not alter on growth arrest. We propose that Theileria-induced lymphocyte proliferation and permanent activation of Hck stems from down-regulation of PAG/Cbp and the concomitant constitutive loss of the negative regulator Csk from the GEMs of transformed B cells.

Animals↗
PubMed2005

Expression of 11beta-hydroxysteroid dehydrogenase type 1 permits regulation of glucocorticoid bioavailability by human dendritic cells.

Glucocorticoids (GCs) exert powerful anti-inflammatory effects that may relate in part to their ability to restrict the differentiation and function of dendritic cells (DCs). Although these inhibitory effects are dependent upon GCs binding to nuclear glucocorticoid receptors (GRs), fine-tuning of GR signaling is achieved by prereceptor interconversion of cortisol that binds GRs with high affinity and cortisone that does not. We show for the first time that human monocyte-derived DCs are able to generate cortisol as a consequence of up-regulated expression of the enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). Immature DCs demonstrate selective enhancement of 11beta-HSD1 reductase activity, leading to increased conversion of inactive cortisone to active cortisol. Enhancement of GC bioavailability is maintained or increased upon terminal differentiation induced by signals associated with innate immune activation. In marked contrast, maturation induced by CD40 ligation leads to a sharp reduction in cortisol generation by DCs. The differentiation of DCs from monocyte precursors is inhibited at physiologic concentrations of inactive cortisone, an effect that requires activity of the 11beta-HSD1 enzyme. In conclusion, prereceptor regulation of endogenous GCs appears to be an important determinant of DC function and represents a potential target for therapeutic manipulation.

11-beta-Hydroxysteroid Dehydrogenase Type 1↗
PubMed2006

E-selectin permits communication between PAF receptors and TRPC channels in human neutrophils.

The selectin family of molecules (L-, P-, and E-selectin) mediates adhesive interactions between leukocytes and endothelial cells required for recruitment of leukocytes to inflammatory sites. Soluble E-selectin levels are elevated in inflammatory diseases and act to promote neutrophil beta(2)-integrin-mediated adhesion by prolonging Ca(2+) mobilization. Although soluble E-selectin alone was unable to initiate Ca(2+) signaling, it allowed a novel "permissive" store-operative calcium entry (SOCE) following the initial platelet-activating factor (PAF)-induced release of Ca(2+) from inositol 1,4,5-trisphosphate (IP(3))-sensitive stores. This induction of permissive SOCE in response to soluble E-selectin and PAF was shown to act through a G protein-coupled receptor (GPCR) coupled to pertussis toxin-insensitive G(q/11). Furthermore, we demonstrated that permissive SOCE was mediated by canonical transient receptor potential channel (TRPC) due to its sensitivity to specific inhibition by MRS1845 and Gd(3+) and that TRPC6 was the principal TRPC family member expressed by human neutrophils. In terms of mechanism, we demonstrated that soluble E-selectin activated Src family tyrosine kinases, an effect that was upstream of phosphatidylinositol 3'-kinase in a signaling pathway that regulates permissive SOCE following exposure of neutrophils to PAF. In summary, this report provides the first evidence for communication between an inflammatory mediator and adhesion receptors at a molecular level, through selectin receptor ligation allowing permissive SOCE to occur following PAF stimulation of human neutrophils.

CD18 Antigens↗
PubMed2006

Serial transplantation of mismatched donor hematopoietic cells between HLA-identical sibling pairs with congenital immunodeficiency: in vivo tolerance permits rapid immune reconstitution following T-replete transplantation without GVHD in the secondary recipient.

We report serial transplantation procedures in 2 sets of brothers with X-linked primary immunodeficiency. The first boy in each family received a T-cell-depleted transplant from a mismatched donor. The recipients then acted as donors for T-replete transplantation of the "tolerized" graft into their HLA-identical brothers with the same disorder. Immune reconstitution was noted to occur at a significantly faster rate in the secondary recipients, and without the occurrence of graft-versus-host disease (GVHD), despite the presence of donor cells mismatched for 1 to 3 HLA antigens. This serial transplantation technique allows the primary recipient of HLA-mismatched donor cells to act as a functionally "HLA-matched" donor for subsequent affected siblings, and should be considered as a therapeutic option in families with congenital disorders.

Child↗
PubMed2006

Chromatin-modifying agents permit human hematopoietic stem cells to undergo multiple cell divisions while retaining their repopulating potential.

Human hematopoietic stem cells (HSCs) exposed to cytokines in vitro rapidly divide and lose their characteristic functional properties presumably due to the alteration of a genetic program that determines the properties of an HSC. We have attempted to reverse the silencing of this HSC genetic program by the sequential treatment of human cord blood CD34(+) cells with the chromatin-modifying agents, 5-aza-2'-deoxycytidine (5azaD) and trichostatin A (TSA). We determined that all CD34(+)CD90(+) cells treated with 5azaD/TSA and cytokines after 9 days of incubation divide, but to a lesser degree than cells exposed to only cytokines. When CD34(+)CD90(+) cells that have undergone extensive number of cell divisions (5-10) in the presence of cytokines alone were transplanted into immunodeficient mice, donor cell chimerism was not detectable. By contrast, 5azaD/TSA-treated cells that have undergone similar numbers of cell divisions retained their marrow repopulating potential. The expression of several genes and their products previously implicated in HSC self-renewal were up-regulated in the cells treated with 5azaD/TSA as compared to cells exposed to cytokines alone. These data indicate that HSC treated with chromatin-modifying agents are capable of undergoing repeated cell divisions in vitro while retaining their marrow-repopulating potential.

Animals↗
PubMed2002

Retroviral transduction of IL2RG into CD34(+) cells from X-linked severe combined immunodeficiency patients permits human T- and B-cell development in sheep chimeras.

X-linked severe combined immunodeficiency (XSCID) is caused by mutations of the common gamma chain of cytokine receptors, gamma(c). Because bone marrow transplantation (BMT) for XSCID does not provide complete immune reconstitution for many patients and because of the natural selective advantage conferred on lymphoid progenitors by the expression of normal gamma(c), XSCID is a good candidate disease for therapeutic retroviral gene transfer to hematopoietic stem cells. We studied XSCID patients who have persistent defects in B-cell and/or combined B- and T-cell function despite having received T cell-depleted haploidentical BMT. We compared transduction of autologous B-cell lines and granulocyte colony-stimulating factor-mobilized peripheral CD34(+) cells from these patients using an MFGS retrovirus vector containing the gamma(c) gene IL2RG pseudotyped with amphotropic, gibbon ape leukemia virus, or RD114 envelopes. Transduced B-cell lines and peripheral CD34(+) cells demonstrated provirus integration and new cell-surface gamma(c) expression. The chimeric sheep model was exploited to test development of XSCID CD34(+) cells into mature myeloid and lymphoid lineages. Transduced and untransduced XSCID CD34(+) cells injected into developing sheep fetuses gave rise to myeloid cells. However, only transduced gamma progenitors from XSCID patients developed into T and B cells. These results suggest that gene transfer to autologous peripheral CD34(+) cells using MFGS-gc retrovirus may benefit XSCID patients with persistent T- and B-cell deficits despite prior BMT.

Animals↗
PubMed2004

A deficiency of CD4+CD25+ T cells permits the development of spontaneous lupus-like disease in mice, and can be reversed by induction of mucosal tolerance to histone peptide autoantigen.

It has been repeatedly shown that a subset of CD4+ T cells that constitutively express CD25 on their surface plays a role in the maintenance of self-tolerance. They may directly or indirectly affect the development of autoimmunity in susceptible mice and humans. In this study, we examine the relationship between the percentage of peripheral CD4+CD25+ T cells and the state of disease in spontaneous models of autoimmune disease. We found that both BWF1 and SNF1 mice that spontaneously develop a lupus-like disease have inherently lower percentage of the CD4+CD25+ T cells in their CD4 repertoire compared with normal Balb/c and DBA/1 mice. The percentage of CD4+CD25+ T cells was found to be increased in both normal and lupus-prone mice as they reached 7 to 8 months of age. However, mice with an autoimmune background differed from mice on a normal background in that the number of CD4+CD25+ T cells never reached 5% of the CD4 population. The lower number of the CD4+CD25+ T cells in autoimmune mice was restored to the level seen in normal mice following administration of histone peptide H471 or OVA(323-339) peptide in the absence of adjuvant intranasally but not intradermally. As such transmucosal treatment may ameliorate disease, we conclude that a deficiency in the CD4+CD25+ T cell pool contributes to a susceptibility to develop spontaneous lupus disease.

Animals↗
PubMed2006

The Society for Clinical Trials opposes US legislation to permit marketing of unproven medical therapies for seriously ill patients.

The proposed Bill S.1956 is a bad law. Wide early access to minimally tested treatments cannot be expected to lead to better or more compassionate care of the seriously ill patient. The long history of medicine is replete with treatments that initially seemed promising to patients, doctors, and especially to their own inventors, but which careful study revealed to be worthless or harmful. We understand the desperate plight of these patients and the importance of hope for them and their families. However, although the proposed law is portrayed as an effort to help patients in desperate need of treatment, in fact its effect would be to undermine the system of scientifically valid testing of new drugs that has been a bulwark of health care for several decades. The effect of the law would be to provide many more possible choices of treatment but much less information upon which to make the choice. Patients would be very unlikely to end up receiving an effective treatment. They would be much more likely to receive useless or possibly harmful treatments in the last days of their lives. The Society for Clinical Trials strongly opposes this legislation.

Clinical Trials as Topic↗
PubMed1981

Insulin permits parathyroid hormone stimulation of 1,25-dihydroxyvitamin D3 production in cultured kidney cells.

Primary cultures of chick kidney cells in serum free medium respond to PTH with increased production of 1,25(OH)2D3 only when exposed to insulin. The response of 1,25(OH)2D3 is maximal at 5 ng bPTH (1-34) per ml and decreases at higher hormone concentrations. Increased 1,25(OH)2D3 synthesis is not evident after 30 minutes exposure to bPTH and is maximal at 4-6 hours of treatment. Insulin does not increase the cyclic AMP response to PTH suggesting that whatever permissive role it is playing occurs beyond the generation of cyclic AMP.

Animals↗