Hyperpolarization-activated Cyclic nucleotide-gated Channel and Cardiac Biological Pacemaker:Part Ⅰ

Hyperpolarization-activated cyclic-nucleotide-gated (HCN) channels in the heart modulate cardiac automaticity via the hyperpolarization-activated cation current ( named Ⅰf, Ⅰh, or Ⅰq). Recent studies have unveiled the molecular identity of HCN (HCN1-4) channels. HCN isoforms are unevenly expressed in the heart, even in the sinoatrial node. Features of HCN currents have been characterized in cardiac and other types of cells or in cell lines transfected with the HCN isoforms. The factors modulating Ih and the physiological significance of HCN channels in the heart have been extensively investigated in recent years. The hypothesis for transplanting and/or creating biological pacemakers to replace diseased sinoatrial and/or atrioventricular nodes has been postulated and tested in animal models. Local overexpression of HCN2 channels in the left atrium or in the left conductive bundle branch of the left ventricle via gene delivery induced significant Ⅰh and escape rhythms during vagal stimulation in canines. In addition, implantation of human mesenchymal stem cells with overexpression of HCN2 channels to the canine left ventricular wall was associated with formation of spontaneous escape rhythms of left-sided origin during vagal-stimulation-induced sinus arrest. This preliminary data suggest that the use of HCN channels may hold great promise in,the development of biological pacemakers.     

Efficient retrovirus transduction of mouse pluripotent hematopoietic stem cells mobilized into the peripheral blood by treatment with granulocyte colony-stimulating factor and stem cell factor

Cytokine-mobilized peripheral blood cells have been shown to participate in hematopoietic recovery after bone marrow (BM) transplantation, and are proposed to be useful targets for retrovirus- mediated gene transfer protocols. We treated mice with granulocyte colony-stimulating factor (G-CSF) and stem cell factor (SCF) to mobilize hematopoietic progenitor cells into the peripheral blood. These cells were analyzed for the number and frequency of pluripotent hematopoietic stem cells (PHSC). We found that splenectomized animals treated for 5 days with G-CSF and SCF showed a threefold increase in the absolute number of PHSC over normal mice. The number of peripheral- blood PHSC increased 250-fold from 29 per untreated mouse to 7,200 in peripheral-blood PHSC in splenectomized animals treated for 5 days with G-CSF and SCF. Peripheral blood PHSC mobilized by treatment with G-CSF and SCF were analyzed for their ability to be transduced by retroviral vectors. Peripheral-blood PHSC from splenectomized animals G-CSF and SCF were transduced with a recombinant retrovirus containing the human MDR-1 gene. The frequency of gene transfer into peripheral blood PHSC from animals treated for 5 and 7 days was two-fold and threefold higher than gene transfer into PHSC from the BM of 5-fluorouracil-treated mice (P < .01). We conclude that peripheral blood stem cells mobilized by treatment with G-CSF and SCF are excellent targets for retrovirus- mediated gene transfer.     

Enzyme-linked immunoabsorbent assay detection of a soluble form of urokinase plasminogen activator receptor in vivo

The receptor for urokinase plasminogen activator (uPA-R, CD87) is a glycosylphosphatidylinositol (GPI)-anchored 50 to 65 kD glycoprotein that, by regulating membrane-associated plasmin activity, may facilitate the invasion of inflammatory and malignant cells. Certain other GPI-anchored glycoproteins are shed from the cell membrane and exist as soluble products in vitro and in vivo. To determine if uPA-R undergoes a similar phenomenon, we have developed a sensitive enzyme- linked immunoabsorbent assay (ELISA) (using a rabbit antiserum as both capture and detection reagents) to measure the quantity of soluble uPA- R (suPA-R) in tissue culture supernatants and biologic fluids. Using this ELISA, we have detected suPA-R in the culture supernatants of U- 937 cells and human monocytes stimulated in vitro by certain soluble inflammatory mediators (Sitrin et al, Blood 84:1268, 1994; Mizukami et al., Clin Res 42:115A, 1994). To determine if suPA-R exists in vivo, we have screened the plasma of 20 normal volunteers (mean +/- SD, 3 +/- 3 ng/mL; median, 2 ng/mL; range, 1 to 11 ng/mL [serum values slightly higher]); the plasma of 13 ICU patients with clinical sepsis syndrome (mean +/- SD, 30 +/- 11 ng/mL; median, 11 ng/mL; range, 4 to 221 ng/mL); and the extravascular fluids (pleural, pericardial, and peritoneal) of 84 individuals with presumed inflammatory or malignant conditions (mean +/- SD, 21 +/- 39 ng/mL; median, 10 ng/mL; range, 2 to 253 ng/mL). Among the latter specimens, most were inflammatory exudates (only six were malignant by positive cytology) with the highest quantities of suPA-R associated with neutrophilic exudates. The solubility of suPA-R contained within these fluids was confirmed by reanalysis after ultracentrifugation to remove particulate material. When tested in a uPA ligand capture ELISA, representative specimens of extravascular body fluids and sepsis plasma contained suPA-R capable of binding uPA ligand (generally representing a small fraction of the immunoreactive material). We conclude from these data that suPA-R is immunologically detectable in vitro and in vivo with high concentrations of receptor found under conditions of inflammatory stimulation. The possibility of suPA-R's biologic activity is suggested by its partial retention of ligand binding capacity.     

Bone marrow collected 14 days after in vivo administration of granulocyte colony-stimulating factor and stem cell factor to mice has 10-fold more repopulating ability than untreated bone marrow

We have examined the repopulating ability of bone marrow and peripheral blood cells collected immediately and at intervals after treatment of donor mice with the combination of granulocyte colony-stimulating factor (G-CSF) and stem cell factor (SCF). Using a competitive repopulation assay we showed that the repopulating ability of peripheral blood cells was highest immediately after cytokine treatment and declined to normal levels within 6 weeks of the termination of treatment with G-CSF and SCF. In contrast the repopulating ability of bone marrow cells was low immediately after cytokine treatment and increased to levels that were 10-fold or more greater than marrow from untreated mice by 14 days after termination of treatment with G-CSF and SCF. This high level of repopulating activity declined to normal levels by 6 weeks after termination of treatment with G-CSF and SCF. The high level of repopulating ability was confirmed by injecting cells from G- CSF- and SCF-treated donors into unconditioned recipients. Peripheral blood cells collected immediately after treatment with G-CSF and SCF engrafted into unconditioned mice sevenfold better than an equivalent number of bone marrow cells from untreated mice. Likewise, bone marrow cells collected 14 days after treatment of the donor animal with G-CSF and SCF engrafted at 10-fold higher levels than an equivalent number of bone marrow cells from untreated mice. We conclude that the treatment of donor mice with G-CSF and SCF causes a transient increase in the repopulating ability of peripheral blood and later of bone marrow. These observations may have applications to clinical hematopoietic stem cell transplantation.     

Repeated transarterial chemoembolisation using different chemotherapeutic drug combinations followed by MR-guided laser-induced thermotherapy in patients with liver metastases of colorectal carcinoma

Background:

To evaluate a treatment protocol with repeated transarterial-chemoembolisation (TACE) downsizing before MR-guided laser-induced interstitial thermotherapy (LITT) using different chemotherapeutic combinations in patients with unresectable colorectal cancer (CRC) liver metastases.

Methods:

Two hundred and twenty-four patients were included in the current study. Transarterial-chemoembolisation (mean 3.4 sessions per patient) was performed as a downsizing treatment to meet the LITT requirements (number⩽5, diameter <5 cm). The intra-arterial protocol consisted of either Irinotecan and Mitomycin (n=77), Gemcitabine and Mitomycin (n=49) or Mitomycin alone (n=98) in addition to Lipiodol and Embocept in all patients. Post TACE, all patients underwent LITT (mean 2.2 sessions per patient).

Results:

Overall, TACE resulted in a mean reduction in diameter of the target lesions of 21.4%. The median time to progression was 8 months, calculated from the start of therapy and the median local tumour control rate was 7.5 months, calculated as of therapy completion. Median survival of patients calculated from the beginning of TACE was 23 months (range 4–110 months), in patients treated with Irinotecan and Mitomycin the median was 22.5 months, Gemcitabine and Mitomycin 23 months and Mitomycin only 24 months with a statistically significant difference between the groups (P<0.01).

Conclusion:

Repeated TACE offers adequate downsizing of CRC liver metastases to allow further treatment with LITT. The combined treatment illustrates substantial survival rates and high local tumour control with statistically significant differences between the three protocols used. Further randomised trials addressing the current study results are required.     

The Experience of Self‐Management in Adolescent Women with Spina Bifida

It is essential for youth with chronic health conditions like spina bifida (SB) to develop self‐management skills to combat vulnerability, achieve self‐sufficiency, and transition to adulthood. The purpose of this qualitative study was to describe the experience of self‐management in 31 adolescent women with SB. Three themes emerged from this study: (1) opportunities to engage in self‐management activities—knowledge, skills, and aspirations; (2) dance of individuation—parental impact on self‐management; and (3) advocacy within self‐management—confronting discrimination and stigma. The findings indicate that assessment and interventions to enhance self‐management in adolescent women with SB are critical for supporting the range of condition‐related and life skills needed for a transition to adulthood and independent living.     

Candida albicans mannan- and protein-induced humoral, cellular and cytokine responses in atopic dermatitis patients

BACKGROUND: The cytokine observed most often in atopic dermatitis (AD) is IL-4, but a role for IL-5 and IFN-gamma in the late and delayed phase reactions has been suggested. In AD with head, neck and shoulder distribution, hypersensitivity to saprophytic yeasts is an important pathogenetic factor. The yeast allergens include both the mannan polysaccharides and the proteins. Mannans are major cross-reacting allergens likely to be involved in the pathogenesis of AD. OBJECTIVE: To characterize the humoral, lymphoproliferative and cytokine (IL-2, 4, 5 and IFN-gamma) responses of peripheral blood mononuclear cells (PBMCs) induced by Candida albicans mannan and protein antigens in AD. METHODS: Fifteen AD patients and seven healthy controls were included. Ficoll-isolated PBMCs were stimulated by PHA and laboratory-generated mannan and protein extracts of C. albicans. Lymphocyte proliferation was measured and cytokine production was studied by ELISA. The antigen-specific IgG and IgE antibodies were analysed by ELISA and nitrocellulose RAST. RESULTS: In AD mannan (P < 0.005) and protein (P < 0.002), specific IgE levels were higher than in healthy controls. Both mannan and protein-specific lymphoproliferations (both: P < 0.02) were higher in AD than in healthy controls. Mannan, but not protein, induced long lasting IL-2 and IL-4 productions from 24 h lasting up to 66-96 h and IL-5 and IFN-gamma productions with elevated levels at 66 and 96 h. The mannan-induced IL-2 (P = 0.015) and IFN-gamma (P < 0.005) were increased in AD as compared with healthy controls. Significant correlations were seen between the protein-induced proliferation responses and both serum total IgE (r = 0.59, P < 0.01) and protein-specific IgE (r = 0.65, P < 0.005). The mannan-induced IL-2 responses correlated with the specific IgE (r = 0.62, P < 0.01) and proliferation (r = 0.51, P < 0.02) and S-IgE level (r = 0.71, P < 0. 002). Mannan-induced IL-4 and IFN-gamma productions also correlated (r = 0.43, P < 0.05). CONCLUSIONS: C. albicans mannan induced elevated IL-2 and IFN-gamma responses in AD patients. The correlations of the cytokine responses with mannan-induced IgE and proliferation responses suggest that C. albicans mannan induced TH1 type cytokine responses are involved in AD.