Oxygen vacancies in Ru/TiO2 - drivers of low-temperature CO2 methanation assessed by multimodal operando spectroscopy

Hydrogenation of CO₂ is very attractive for transforming this greenhouse gas into valuable high energy density compounds. In this work, we developed a highly active and stable Ru/TiO₂ catalyst for CO₂ methanation prepared by a solgel method that revealed much higher activity in methanation of CO₂ (ca. 4–14 times higher turnover frequencies at 140–210°C) than state-of-the-art Ru/TiO₂ catalysts and a control sample prepared by wetness impregnation. This is attributed to a high concentration of O-vacancies, inherent to the solgel methodology, which play a dual role for 1) activation of CO₂ and 2) transfer of electrons to interfacial Ru sites as evident from operando DRIFTS and in situ EPR investigations. These results suggest that charge transfer from O-vacancies to interfacial Ru sites and subsequent electron donation from filled metal d-orbitals to antibonding orbitals of adsorbed CO are decisive factors in boosting the CO₂ methanation activity.

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Solgel prepared Ru/TiO₂ outperforms methanation activity of similar materials

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Reliable insight of O-vacancies role is gained by combined operando techniques

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Enhanced interaction of O-vacancy-Ru⁰ sites boosts methane rate

Localization of peripheral dopamine D1 and D2 receptors in rat corpus cavernosum

OBJECTIVE

To detect and locate anatomically peripheral dopamine D1 and D2 receptors in rat cavernosa, as dopamine is important in sexual drive and penile erection through receptors located in the central nervous system.

MATERIALS AND METHODS

Corpora cavernosa were obtained from Sprague-Dawley rats; total RNA and membrane proteins were extracted and cryostat sections prepared. The rat brain hypothalamus was used as a control for dopamine D1 and D2 receptors. The presence and expression of peripheral dopamine D1 and D2 receptor mRNAs in rat corpus cavernosa was assessed using reverse transcription and polymerase chain reaction (RT-PCR), and Northern blot hybridization using (32)P-UTP-labelled RNA probes. Concurrently, corresponding proteins from D1 and D2 receptors were assayed and detected by a Western blotting technique. The anatomical location of dopamine D1 and D2 receptor mRNAs in rat penile tissues was identified by in situ hybridization using (35)S-UTP-labelled RNA probes in cryostat sections. Immunohistochemical staining was used to locate peripheral dopamine D1 and D2 receptor proteins in rat corpora cavernosa.

RESULTS

Dopamine D1 and D2 receptor gene expression was detected in rat corpora cavernosa. In situ hybridization signals for dopamine D1 and D2 receptor mRNAs were localized to corpus cavernosal tissues and dorsal vessels in the rat penis. Western blot analyses showed peripheral dopamine D1 and D2 receptor proteins in rat corpora cavernosa. Immunohistochemically, peripheral dopamine D1 and D2 receptor proteins were detected in dorsal nerves, dorsal vessels and corpus cavernosal smooth muscle of the rat penile tissues.

CONCLUSIONS

Peripheral dopamine D1 and D2 receptors are present in the corpora cavernosa of rats. The functional significance of these receptors and signal transduction pathways in modulating the vascular tone of the penis warrants further investigation.

Comparison of two doses of intravenous immunoglobulin after allogeneic bone marrow transplants

Intravenous immunoglobulin has been used after bone marrow transplants to prevent infections and acute graft-versus-host disease. However, the minimum dose required for protection is unknown. This may have significant economic implications. A multicenter randomized clinical trial compared the impact of two intravenous immunoglobulin doses on systemic infections and acute graft-versus-host disease in transplant recipients. Either 250 mg/kg or 500 mg/kg was given weekly from day -8 to day +111. Multivariate analysis was used to assess the effect of dose and other risk factors on event-free survival, systemic infection, and acute graft-versus-host disease. The two-dose cohorts had similar event-free survival and infection frequencies. The higher dose was associated with less acute graft-versus-host disease (P = 0.03).

Successful salvage using mismatched umbilical cord blood transplant in an adult with recurrent acute myelogenous leukemia failing autologous peripheral blood progenitor cell transplant: a case history and review

We report a 26-year-old female with AML, FAB classification M5 who was initially treated with induction therapy consisting of idarubicin and cytarabine followed by high-dose cytarabine and autologous peripheral blood progenitor cell (PBPC) transplant for consolidation. The patient remained in remission for 1 month post-PBPC transplant, when relapse was noted. Reinduction therapy with idarubicin, cytarabine and etoposide was unsuccessful, and the patient underwent an unrelated, two-antigen mismatched umbilical cord blood (UCB) transplant for salvage after melphalan plus total body irradiation. Complications post transplant included veno-occlusive disease, delayed engraftment, and acute grade III graft-versus-host disease (GVHD). The patient remains in remission 1 year post transplant. This study demonstrates the salvage capability of UCB transplantation for refractory leukemia and its potential use in adult patients.

Antisense down-regulation of metallothionein induces growth arrest and apoptosis in human breast carcinoma cells

The association of increased metallothionein (MT) gene expression in breast cancer with metastasis and poor prognosis has led us to investigate the hypothesis that inhibition of MT gene expression may elicit antiproliferative effects in breast carcinoma MCF7 cells. To monitor the effect of downregulation of MT protein on growth, MCF7 cells were transiently transfected by electroporation with an 18-mer MT antisense phosphorothioate oligomer (AO) or an 18-mer random oligomer (RO). The MT-AO is complementary to the region 7 bases downstream from the AUG translational start site of the hMT-IIA gene. Transfection of MCE7 cells with the AO inhibited cell growth by 50-60% at 72 hours when compared to control cells or the cells transfected with RO. The AO-induced growth inhibition was associated with alterations in morphology suggestive of apoptotic cell death. This was further confirmed by DNA linker cleavage into oligonucleosomal fragments and decreased bcl-2 protein levels in AO-transfected cells as opposed to the RO-transfected cells. Reverse transcriptase polymerase chain reaction analysis showed that AO induced a 2-fold increase in the levels of c-fos and p53 transcripts in comparison to RO which had no significant effect. Conversely, c-myc transcripts were decreased by 2.5-fold in the AO-transfected cells when compared to the controls. Furthermore, MCF7 cells transfected with an expression plasmid pBAcNEO-sMT-IIA encompassing human MT-IIA cDNA, constitutively driven by beta-actin promotor, caused a 2.5-fold increase in intracellular levels of MT, as judged by PCR and western blot analysis, in comparison to the cells transfected with pBAcNEO plasmid. In contrast to the AO-induced growth inhibition, overexpression of cytoplasmic MT increased the cell multiplication by 2-fold compared with control cells or the cells transfected with the control plasmid 72 hours post-transfection. Moreover, the effects of AO on oncogene expression were reversed on increased expression of MT. These data suggest that overexpression of MT potentiates the growth of MCF7 cells, whereas downregulation of MT elicits antiproliferative effects.

Effects of CD34+ selection and T cell immunodepletion on cord blood hematopoietic progenitors: relevance to stem cell transplantation

Cord blood (CB) has been used recently for stem cell transplantation. We have investigated two different approaches to deplete CB samples of T cells capable of mounting graft-vs.-host disease (GVHD). The methods used were selection of CD34+ cells using avidin-biotin columns (CellPro) and T cell immunodepletion with T10B9 monoclonal antibody (mAb) plus complement. Using the avidin-biotin columns, 10.3% of the original CD34+ cells were recovered. Although this technique yielded a population containing 60 +/- 5.5% CD34+ cells, about 1 log of CFU-GM progenitors were lost. In contrast, after the T10B9 mAb and complement immunodepletion, 75 +/- 19% and 62 +/- 7% of the CD34+ cells and CFU-GM were recovered, respectively. T cell depletion was 3.6 logs using the CellPro columns and 2.2 logs after immunodepletion. To investigate whether cell losses following T cell depletion could be overcome by ex vivo expansion, cells were cultured in the presence of recombinant human interleukin-3 (rhIL-3) and recombinant human c-kit ligand (stem cell factor [rhSCF]) for 7 days. There were 14- and six-fold expansions in the number of progenitors recovered after CellPro and immunodepletion, respectively. To asses the engraftment potential of expanded cells, we used a murine transplantation model in which the presence of human cells was identified by the anti-CD45 mAb. Cells expanded in vitro engrafted in irradiated BNXid mice as efficiently as nonexpanded cells, suggesting that expansion did not affect their transplantability. This study shows that both techniques resulted in significant T cell depletion of CB. Furthermore, in vitro expansion could overcome cell losses sustained during the separation techniques without impairing the engraftment potential of the expanded cells.

Neutrophil pool sizes and granulocyte colony-stimulating factor production in human mid-trimester fetuses

We quantified neutrophils and neutrophil progenitors, and assessed granulocyte colony-stimulating factor (G-CSF) production in the liver and bone marrow of 20 human abortuses after elective pregnancy termination between 14 and 24 wk of gestation. Mature neutrophils were not observed in any of the liver specimens, but were present in the bone marrow as early as 14 wk. The concentrations of neutrophils in the fetal marrow were extremely low, by comparison with term infants and adults, with less than 5% of the nucleated cells being segmented neutrophils, band neutrophils, or metamyelocytes compared with 31-69% in term infants. Despite the low neutrophil populations, progenitors which had the capacity for clonal maturation into neutrophils in vitro were abundant in the fetal liver and fetal bone marrow. In addition, such progenitors had a dose-response relationship to recombinant G-CSF similar to that of progenitors from the bone marrow of healthy adults. At each gestational age tested, stimulation of mononuclear cells from fetal liver with IL-1 alpha generated less G-CSF protein and fewer G-CSF mRNA transcripts than did stimulation of mononuclear cells from fetal bone marrow. Mononuclear cells from the fetal bone marrow produced less G-CSF protein and mRNA than did mononuclear cells from the blood of adults. Thus, the liver of the mid-trimester human fetus is almost devoid of neutrophils, and the bone marrow contains a significantly lower proportion of neutrophils than does the marrow of term neonates or adults. These findings correlate with IL-1 alpha-induced production of G-CSF in these organs.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of recombinant GM-CSF and G-CSF on the bone marrow cells of children with acute lymphoblastic leukemia

Colony stimulating factors (CSFs) are glycoprotein hormones that regulate growth and differentiation of hematopoietic progenitor cells. Their use to stimulate granulocyte precursors during periods of neutropenia in patients with acute myeloid leukemia (AML) is limited by their concomitant stimulation of the proliferation of myeloblasts. The effects of these agents on leukemic lymphoblasts is not entirely known. We have investigated the in vitro effects of granulocyte-CSF (G-CSF) and granulocyte/macrophage-CSF (GM-CSF) on leukemic cells from children with acute lymphoblastic leukemia (ALL). DNA synthesis of bone marrow cells from 22 children with ALL, either at diagnosis or in relapse, was examined with and without CSFs. Proliferative potential was also tested in a clonogenic assay with 13 bone marrow specimens. These factors did not stimulate the growth of ALL cells in either assay. Our results indicate that G-CSF and GM-CSF should be able to stimulate granulocyte proliferation without enhancing leukemic proliferation during periods of neutropenia in children with ALL.

Phase I study of recombinant human interleukin-2 for pediatric malignancies: feasibility of outpatient therapy. A Pediatric Oncology Group Study

Published data indicate that when recombinant interleukin-2 (rIL-2) is administered to children as a 15-min i.v. bolus, doses of 18 x 10(6) IU/m2 are poorly tolerated, requiring intensive care unit (ICU) management of IL-2-induced hypotension. We administered rIL-2 as a 1- or 2-h i.v. infusion to 11 children with malignancies refractory to conventional therapy. IL-2 was given every Monday/Wednesday/Friday for 3 weeks. Four children received 12 x 10(6) IU/m2/dose, four received 18 x 10(6) IU/m2/dose, and three received 24 x 10(6) IU/m2/dose (1 Cetus Unit = 6 IU). Fever, chills, flushing, nausea, vomiting, transient weight gain, and oliguria were observed at all three dose levels (not dose-limiting toxicities). Cardiovascular toxicity was significantly reduced compared to the bolus regimen. Mild hypotension was observed at all three dose levels; however, there was no severe dose-limiting hypotension. Because of reduced cardiovascular toxicity, IL-2 was safely administered on an outpatient basis. This regimen induced marginal transient increases in natural killer cell activity and lymphokine-activated killer cell activity. No measurable clinical tumor response was observed in any of the 11 children. The maximum-tolerated dose has not been reached. This regimen allows for a considerable cost reduction (outpatient care instead of ICU care) and safety, making further clinical trials on the use of IL-2 in children more feasible.

Clinical characteristics and treatment outcome of children with acute lymphocytic leukemia and Down's syndrome. A Pediatric Oncology Group study

Of 2947 children with acute lymphocytic leukemia (ALL), treated during three consecutive studies of the Pediatric Oncology Group (1974-1986), 52 (1.8%) had Down's Syndrome (DS). Comparison of clinical and laboratory characteristics showed no significant differences in leukocyte count, racial distribution, sex ratio, platelet count, incidence of mediastinal mass, lymphadenopathy or hepatosplenomegaly, or percentage of blood or bone marrow blasts for children with ALL with or without Down's Syndrome (DS-ALL or NDS-ALL, respectively). However, children with DS-ALL were slightly older at the time of presentation and had higher hemoglobin values. The relative frequency of each major immunophenotype (early pre-B, pre-B, T, or B) was also comparable for patients with or without DS. For this report, treatment regimens were categorized as either conventional (no consolidation therapy) or intensive. Cox regression analysis revealed that the presence of DS, a higher leukocyte count, black race, or age older than 10 years was independently associated with a poorer event-free survival (EFS) for children treated with conventional chemotherapy. However, for the cohort of children who received intensive chemotherapy, DS was no longer an independent risk factor. In fact, event-free survival (EFS) was markedly improved to a level comparable with that observed in the children diagnosed as having NDS-ALL. On the other hand, serious toxicity, requiring interruption of treatment, was significantly more frequent in the intensively treated children with DS compared with similarly treated patients with NDS-ALL, although deaths resulting from toxicity occurred infrequently.

Pharmacokinetics of recombinant interleukin-2 in children with malignancies: a Pediatric Oncology Group study

To develop effective interleukin-2 (IL-2) protocols for pediatric malignancies, it is important to define IL-2 pharmacokinetics in children. In a phase I trial, we studied IL-2 pharmacokinetics in seven children, aged 6-18, five with leukemia, one with neuroblastoma, and one with rhabdomyosarcoma. IL-2 was administered as a 15-min i.v. infusion of either 1 X 10(6) CU/m2/dose or 3 X 10(6) CU/m2/dose (every Monday, Wednesday, and Friday for 3 weeks). IL-2 levels were determined using an IL-2-dependent murine T lymphocyte cell line bioassay. Peak IL-2 levels of 120-426 and 330-740 CU/ml were achieved after the lower and higher doses, respectively. Pediatric IL-2 kinetics resembled data reported for adults, fitting a two-compartment model (least-squares-regression technique), with an alpha half-life of 14.0 +/- 5.6 min (range, 6.3-23.1) and a beta half-life of 51.4 +/- 10.7 min (range, 33.0-66.0). The volume of distribution approximated total extracellular fluid (mean, 0.18 L/kg). Further clinical trials are needed to identify which pediatric malignancies are sensitive to immunotherapy and to establish the optimal treatment regimens.

Cytotoxicity of purified Leu 19+ cells from the peripheral blood of children with acute lymphocytic leukemia

Several investigators have reported decreased natural killer cell activity of the peripheral blood from children with acute leukemia both at diagnosis and in relapse. This study was to determine whether this decreased natural killer activity is the result of a diminished number or defective function of natural killer cells or both. The percentage of Leu 19+ (NKH-1, CD56) and the lytic activity of a purified Leu 19+ population from the peripheral blood of children with acute lymphocytic leukemia as well as from healthy children were determined. This cell population mediates most natural killer and natural killer-like activity in the peripheral blood. Twenty-three children with acute lymphocytic leukemia (16 at diagnosis, seven in relapse) as well as six control children were studied. The percentage of Leu 19+ cells was significantly lower in the blood of children either at initial diagnosis (median, 3%; P less than 0.005) or in relapse (median, 1%; P less than 0.01) than that for the control children (median, 12.5%). The cytotoxicity of peripheral blood mononuclear cells (PBMC) against K562 in 3-hour 51Cr release assay was significantly lower for patients either at diagnosis (median, 8.5 lytic units[LU]/10(7) cells; P less than 0.005) or in relapse (median, 3 LU/10(7) cells; P less than 0.005) than that for normal controls (median, 97 LU/10(7) cells). The lytic activity of a fluorescent activated cell sorter (FACS) purified Leu 19+ population was evaluated. The Leu 19+ cells were sorted from PBMC of 11 children with acute lymphocytic leukemia who had more than 2% Leu 19+ cells in their PBMC (nine at diagnosis and two in relapse). The lytic activity of sorted Leu 19+ cells was significantly (P less than 0.04) lower for patients at initial diagnosis (median, 45 LU/10(7) cells) than that for normal control children (median, 317 LU/10(7) cells). One of the two children studied at relapse had low Leu 19+ lytic activity. The authors concluded that (1) The percentage of Leu 19+ cells in the peripheral blood of the majority of children with acute lymphocytic leukemia either at diagnosis or in relapse is below normal; (2) The lytic activity of PBMC from the majority of children with acute lymphocytic leukemia is reduced both at diagnosis and in relapse; and (3) The lytic activity of Leu 19+ purified PBMC is reduced in the majority of children with acute lymphocytic leukemia. These findings confirm the defective natural killer cell profile in children with acute lymphocytic leukemia both at the time of diagnosis and in relapse.

Natural killer cells in children with malignant solid tumors. Effect of recombinant interferon-alpha and interleukin-2 on natural killer cell function against tumor cell lines

Natural killer (NK) cells and NK cell activity were determined in three groups (newly diagnosed [n = 21], on therapy [n = 21], and off therapy [n = 18]) of children with various types of malignant solid tumors and in a control group (n = 26) by means of Leu-7 and Leu-11b monoclonal antibodies and a 4-hour 51Cr-release assay, respectively. The erythroleukemia cell line K562 was used as a target cell. The newly diagnosed group included eight patients with localized disease (Stage I-II), ten with bulky but nonmetastatic disease (Stage III), and three with metastases (Stage IV). The mean percent of NK cell activity in the newly diagnosed group was significantly higher than that of the control group. Children with Stage III tumors at diagnosis had higher mean NK cell function than those with Stage I-II and Stage IV. On therapy patients had significantly fewer NK cells and lower NK cell cytotoxicity than those in the other groups studied. We also studied the following: (1) the in vitro effect of recombinant interferon-alpha (rIFN-alpha) and recombinant interleukin-2 (rIL-2) on NK cell function of peripheral blood lymphocytes (PBL) from children with solid malignancies; and (2) the susceptibility of neuroblastoma-derived (CHP-126 and SKNSH) and rhabdomyosarcoma-derived (A-204) cell lines to NK cell lysis. Both rIFN-alpha and rIL-2 enhanced NK cell activity of PBL from children with malignancies and healthy children against K562 and solid tumor cell lines. The enhancing effect or rIL-2 was greater than that of rIFN-alpha. CHP-126 and SKNSH cell lines were susceptible to NK cell lysis mediated by the PBL of children with neuroblastoma and the control group. The A-204 cell line was less sensitive than K562 to NK cell cytotoxicity. Our results suggest a potential therapeutic role for both cytokines in the treatment of malignant solid tumors of childhood.