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At least 307 records · Page 17Linked to original sources

PubMed2006

Intracoronary bone marrow cell transfer after myocardial infarction: eighteen months' follow-up data from the randomized, controlled BOOST (BOne marrOw transfer to enhance ST-elevation infarct regeneration) trial.

BACKGROUND: Intracoronary transfer of autologous bone marrow cells (BMCs) may enhance recovery of left ventricular (LV) function in patients after acute myocardial infarction (AMI). However, clinical studies addressing the effects of BMCs after AMI have covered only limited time frames ranging from 3 to 6 months. The critical question of whether BMC transfer can have a sustained impact on LV function remains unanswered. METHODS AND RESULTS: After percutaneous coronary intervention with stent implantation (PCI) of the infarct-related artery, 60 patients were randomized 1:1 to a control group with optimal postinfarction therapy and a BMC transfer group that also received an intracoronary BMC infusion 4.8+/-1.3 days after PCI. Cardiac MRI was performed 3.5+/-1.5 days, 6+/-1 months, and 18+/-6 months after PCI. BMC transfer was not associated with adverse clinical events. In the control group, mean global LV ejection fraction increased by 0.7 and 3.1 percentage points after 6 and 18 months, respectively. LV ejection fraction in the BMC transfer group increased by 6.7 and 5.9 percentage points. The difference in LVEF improvement between groups was significant after 6 months but not after 18 months (P=0.27). The speed of LV ejection fraction recovery over the course of 18 months was significantly higher in the BMC transfer group (P=0.001). CONCLUSIONS: In this study, a single dose of intracoronary BMCs did not provide long-term benefit on LV systolic function after AMI compared with a randomized control group; however, the study suggests an acceleration of LV ejection fraction recovery after AMI by BMC therapy.

Adult↗

PubMed2004

Asymmetric electron transfer in cyanobacterial Photosystem I: charge separation and secondary electron transfer dynamics of mutations near the primary electron acceptor A0.

Point mutations were introduced near the primary electron acceptor sites assigned to A0 in both the PsaA and PsaB branches of Photosystem I in the cyanobacterium Synechocystis sp. PCC 6803. The residues Met688PsaA and Met668PsaB, which provide the axial ligands to the Mg2+ of the eC-A3 and eC-B3 chlorophylls, were changed to leucine and asparagine (chlorophyll notation follows Jordan et al., 2001). The removal of the ligand is expected to alter the midpoint potential of the A0/A0- redox pair and result in a change in the intrinsic charge separation rate and secondary electron transfer kinetics from A0- to A1. The dynamics of primary charge separation and secondary electron transfer were studied at 690 nm and 390 nm in these mutants by ultrafast optical pump-probe spectroscopy. The data reveal that mutations in the PsaB branch do not alter electron transfer dynamics, whereas mutations in the PsaA branch have a distinct effect on electron transfer, slowing down both the primary charge separation and the secondary electron transfer step (the latter by a factor of 3-10). These results suggest that electron transfer in cyanobacterial Photosystem I is asymmetric and occurs primarily along the PsaA branch of cofactors.

Amino Acid Substitution↗

PubMed1986

A study of the relationship between placental non-haem iron and iron transfer in the guinea pig: the maturation of the transfer process.

The relationship between placental non-haem iron and placental iron transfer has been studied in the guinea pig. From day 25 to day 50, non-haem iron and iron transfer increase. Expressed on placental wet weight or per g of placental DNA, iron transfer and non-haem iron were inversely related; an increase of transfer was accompanied by a decrease of the non-haem iron content. The results are discussed in terms of the hypothesis, that accumulation of non-haem iron in early pregnancy is caused by an imbalance between iron uptake and iron transfer. The steady increase of total non-haem iron till term which has been demonstrated in this study is in contradiction with this hypothesis. The paper describes an alternative hypothesis in which placental non-haem iron, most likely ferritin iron, is assumed to play an active role in the regulation of placental iron transfer.

Animals↗

PubMed1980

Studies on electron transfer from general acyl-CoA dehydrogenase to electron transfer flavoprotein.

General acyl coenzyme A dehydrogenase from pig liver mitochondria, which was prepared as a complex with C8CoA and mixed with electron-transfer flavoprotein, rapidly reduces the electron-transfer flavoprotein to a 1-electron-reduced form (anionic semiquinone). A second electron is transferred more slowly to form the fully reduced electron-transfer flavoprotein. Transfer of the first electron is faster than turnover in the dichlorophenolindophenol reduction assay. These observations show that the acyl-CoA dehydrogenase-electron-transfer flavoprotein system utilizes this semiquinone catalytically. A concomitant appearance of semiquinone from the general acyl-CoA dehydrogenase could not be detected under similar conditions.

Acyl-CoA Dehydrogenases↗

PubMed1977

Rat liver proteins capable of transferring phosphatidylethanolamine. Purification and transfer activity for other phospholipids and cholesterol.

Two proteins, one in a highly purified form, have been isolated from the soluble fraction of rat liver homogenate. These proteins accelerate the transfer of labeled phosphatidylethanolamine, phosphatidylcholine, phosphatidylinositol, sphingomyelin, and cholesterol from liposomes to mitochondria or erythrocyte ghosts. The fraction obtained after ammonium sulfate precipitation, gel filtration on Sephadex G-75, ion-exchange chromatography on CM-cellulose, ampholyte displacement chromatography, and heat treatment exhibited an 876-fold increase in its phosphatidylethanolamine transfer activity as compared with the postmitochondrial supernatant adjusted to pH 5.1. Isoelectric focusing on polyacrylamide gels shows a single band between pH 8.6 and 9.0. The transfer activity is abolished by trypsin, but withstands 5-min heating at 90 degrees. After heat treatment, a single major band is seen on polyacrylamide gel electrophoresis followed by two minor ones. The molecular weight of the major band is 12,500, as determined by electrophoresis on 15% polyacrylamide gels in the presence of sodium dodecyl sulfate. A molecular weight of 13,500 was calculated from molecular filtration through Sephadex G-50. The relative transfer activities toward the different phospholipids remain constant throughout the last three steps of the purification procedure in spite of the extensive change in the electrophoretic profile of the protein mixture. The cholesterol transfer activity remains unchanged after the final heat treatment as well. This indicates that all of the transfer activities are present in a single protein.

Animals↗

PubMed1997

Electron transfer in DNA? Competition by ultra-fast proton transfer?

Interstrand proton transfer, which is driven by the large changes in acidity or basicity that result from loss or uptake of an electron from or by a base in a base pair of DNA, can constitute a very powerful stop to the migration of holes or electrons in the direction of the DNA helix via the stacked bases. In theory, such a proton transfer could have the same rate (10(14) s[-1]) as the electron transfer. In base pair model systems, proton transfer rates up to 10(13) s(-1) have been measured. As a result of the existence of proton transfer barriers to electron transfer, the migration distance of the charge carriers in DNA is likely to be short, extending over only < or = 5 bp's (17 angstroms).

Base Composition↗

PubMed2006

Correlations of structure and rates of energy transfer for through-bond energy-transfer cassettes.

Fluorescent DNA-labeling cassettes are designed to have a common absorbing chromophore matched to a single exciting laser wavelength, but up to four different emitters. Experiments reported here have examined the energy-transfer rates and fluorescence polarization characteristics for two different types of cassette, involving three distinct relative orientations of the donor and acceptor transition moments and the axis of the rigid linker. Energy-transfer times range from <200 fs to approximately 20 ps, the fastest transfer times occurring when the transition moments of the donor and acceptor species are aligned parallel to the linker axis. Experimental evidence is presented that supports a through-bond energy-transfer mechanism, in contrast with a commercial DNA-labeling agent, which exhibits much slower transfer times controlled by FRET. These rigid cassettes also exhibit polarized fluorescence from the acceptor species, so that this particular type of DNA-labeling probe has some of the advantages of single-molecule probes such as rhodamine and coumarin dyes.

DNA Probes↗

PubMed2001

Evaluation of phospholipid transfer protein and cholesteryl ester transfer protein as contributors to the generation of pre beta-high-density lipoproteins.

High-density lipoproteins (HDLs) are considered anti-atherogenic because they mediate peripheral cell cholesterol transport to the liver for excretion and degradation. An important step in this reverse cholesterol-transport pathway is the uptake of cellular cholesterol by a specific subclass of small, lipid-poor apolipoprotein A-I particles designated pre beta-HDL. The two lipid-transfer proteins present in human plasma, cholesteryl ester transfer protein (CETP) and phospholipid transfer protein (PLTP), have both been implicated in the formation of pre beta-HDL. In order to investigate the relative contribution of each of these proteins, we used transgenic mouse models. Comparisons were made between human CETP transgenic mice (huCETPtg), human PLTP transgenic mice (huPLTPtg) and mice transgenic for both lipid-transfer proteins (huCETPtg/huPLTPtg). These animals showed elevated plasma levels of CETP activity, PLTP activity or both activities, respectively. We evaluated the generation of pre beta-HDL in mouse plasma by immunoblotting and crossed immuno-electrophoresis. Generation of pre beta-HDL was equal in huCETPtg and wild-type mice. In contrast, in huPLTPtg and huCETPtg/huPLTPtg mice, pre beta-HDL generation was 3-fold higher than in plasma from either wild-type or huCETPtg mice. Our findings demonstrate that, of the two plasma lipid-transfer proteins, PLTP rather than CETP is responsible for the generation of pre beta-HDL. These data support the hypothesis of a role for PLTP in the initial stage of reverse cholesterol transport.

Animals↗

PubMed2005

Comparison of two approaches to nuclear transfer in the bovine: hand-made cloning with modifications and the conventional nuclear transfer technique.

The aim of the present study was to compare the in vitro and in vivo developmental competence of hand-made cloning (HMC) embryos with the conventional nuclear transfer (NT) method using five somatic cell lines and in vitro-fertilised (IVF; control) embryos. Modifications to the HMC procedure included fusion efficiency optimisation, effect of cytoplasmic volume and cloned embryo aggregation. The developmental competence of blastocysts from each of the treatment groups and cell lines used was assessed following transfer to 345 recipients. Vitrification was also used to enable management of recipient resources and to assess the susceptibility of membranes to cryopreservation following zona removal. Increasing cytoplasmic volume to 150% or aggregating two embryos improved the blastocyst development rate and increased the total cell number. Although HMC embryo transfers established a significantly higher pregnancy rate on Day 30 than fresh IVF or NT embryo transfers, the overall outcome in terms of cloned live births derived from either fresh or vitrified/thawed HMC or NT embryo transfers across the five cell lines did not differ. The birth and continued survival of clones produced with HMC technology with equivalent efficiency to NT shows that it can be used as an alternative method for the generation of cloned offspring in the bovine.

Animals↗

PubMed2003

Photoinduced intramolecular electron transfer and triplet energy transfer in a steroid-linked norbornadiene-carbazole dyad.

Bichromophoric compound 3 beta-((2-(methoxycarbonyl)bicyclo[2.2.1]hepta-2,5-diene-3-yl)carboxy)androst-5-en-17 beta-yl-[2-(N-carbazolyl)acetate] (NBD-S-CZ) was synthesized and its photochemistry was examined by fluorescence quenching, flash photolysis, and chemically induced dynamic nuclear polarization (CIDNP) methods. Fluorescence quenching measurements show that intramolecular electron transfer from the singlet excited state of the carbazole to the norbornadiene group in NBD-S-CZ occurs with an efficiency (Phi SET) of about 14 % and rate constant (kSET) of about 1.6 x 10(7) s-1. Phosphorescence and flash photolysis studies reveal that intramolecular triplet energy transfer and electron transfer from the triplet carbazole to the norbornadiene group proceed with an efficiency (TET + TT) of about 52 % and rate constant (kTET + kTT) of about 3.3 x 10(5) s-1. Upon selective excitation of the carbazole chromophore, nuclear polarization is detected for protons of the norbornadiene group (emission) and its quadricyclane isomer (enhanced absorption); this suggests that the isomerization of the norbornadiene group to the quadricyclane proceeds by a radical-ion pair recombination mechanism in addition to intramolecular triplet sensitization. The long-distance intramolecular triplet energy transfer and electron transfers starting both from the singlet and triplet excited states are proposed to proceed by a through-bond mechanism.

Androstenes↗

PubMed1988

Pregnancies following the interval double-transfer technique in an in vitro fertilization-embryo transfer program.

In 16 women undergoing IVF-ET, with more than four embryos available, two transfers were performed (24 hr apart), instead of one. The pregnancy rate was 25%, as compared with a pregnancy rate of 6.2% in 16 women having fewer than four embryos available and in whom one conventional transfer was performed. Since in our IVF-ET program, we do not freeze the extra embryos available, the purpose of the double transfer was to use all the embryos available and to improve the chances of finding the "implantation window" open. It is our feeling that multiple transfers may be beneficial to improve the pregnancy rate in an IVF-ET program without freezing facilities. However, a larger controlled clinical trial is necessary, in order to establish the advantages of multiple transfers in terms of pregnancy rate in comparison with the potential disadvantages.

Embryo Transfer↗

PubMed1994

Gene transfer efficiency during gestation and the influence of co-transfer of non-manipulated embryos on production of transgenic mice.

Litter size of DNA microinjected zygotes is lower than for non-manipulated zygotes. The rate of embryonic and fetal survival in early, mid and late gestation was determined to assess whether DNA integration was responsible for embryonic losses. Also, the effect of including non-microinjected embryos with injected embryos on pregnancy rate and transgenic pup production was determined. In Experiment 1, one-cell embryos from immature CD-1 mice were microinjected with a whey acidic protein promoter-human protein C gene construct. One hour after microinjection embryos were transferred to pseudopregnant recipients (45 transfers of 30 embryos each). Fifteen recipients were sacrificed on day 4, 12 and 18 of gestation and the embryos/fetuses analysed for the transgene. The percentage of embryos or fetuses that were positive for the transgene was not significantly different at any day. However, the number of viable embryos at day 4 was significantly greater than fetuses on days 12 or 18. In addition, a high degree of mosaicism was observed in day 18 fetuses and placentae recovered. In Experiment 2, one-cell embryos from CD-1 mice were microinjected and co-transferred with non-manipulated embryos (C57BL/6). Pregnancy rate and the total number of pups born were improved by addition of non-injected embryos. However, the number of transgenic mice produced was similar whether non-injected embryos were included or not. There were 32.2% (15/46) transgenic pups when 0 non-injected embryos were transferred compared with 15.1% (13/86) transgenic pups when 4 or 8 non-injected embryos were added to the transfers. In summary, a high degree of embryonic and fetal mortality occurs among microinjected embryos.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1981

Passive transfer of immunity to trichostrongyle species infections in sheep. Investigations of specificity and limitations of 'transfer factor' activity with Trichostrongylus axei infections.

The ability of transfer factor (TF) preparations to transfer resistance to challenge with Trichostrongylus axei in sheep and to correct partially the immune immaturity of young lambs was confirmed. Non-dialysed TF consistently transferred resistance but dialysed TF frequently failed, perhaps demonstrating a loss of activity during TF preparation procedures. Specificity of transfer was demonstrated when T. axei TF transferred resistance to T. axei challenge but Haemonchus contortus TF failed to do so.

Animals↗

PubMed1980

Energy transfer in artificial membrane systems. Singlet-singlet energy transfer from alloxazines to isolloxazines in dipamitoyl phosphatidylcholine liposomes and dialkylammonium chloride vesicles.

The singlet-singlet energy transfer from alloxazines to isoalloxazines has been investigated in dialmitoyl phosphatidylcholine (DPPC) liposomes and dioctadecyltrimethylammonium chloride (2C18NC) vesicles to clarify the role of the artificial membranes in the energy transfer phenomenon. The structures of the artificial membranes were divided into two types: the single-walled (sonicated DPPC) and the multi-compartment vesicles (unsonicated DPPC and sonicated 2C18NC). In the DPPC single-walled liposomes, the energy of the donor lost by quenching is efficiently transferred to the acceptor via the Förster-type dipoledipole interaction. In the case of multi-compartment liposomes of DPPC, the mean distance between donor and acceptor is so small because the external surface of a bilayer is in the vicinity of the internal surface of another bilayer. As a consequence, efficiencies both of energy transfer and of energy loss were greater than those in single-walled liposomes. The fluid property of the 2C18NC bilayer allowed the preferential collisional quenching. The marked reduction in the efficiencies of both energy transfer and energy loss were attributed to the elongation of donor-acceptor distances due to the increase of the size of liposome.

Energy Transfer↗

PubMed1991

Effects of hyperlipidemias in hamsters on lipid transfer protein activity and unidirectional cholesteryl ester transfer in plasma.

Experiments were performed to characterize plasma lipid transfer protein activity (LTA), and the rate of [3H]CE transfer from HDL to lower density lipoproteins in plasma of hamsters. Compared to rabbits, hamster plasma has about one-tenth the level of d greater than 1.21 LTA but a relatively high level of VLDL-triacylglycerols, and a higher fractional rate of HDL-[3H]CE transfer in plasma (in vitro) than predicted by the d greater than 1.21 LTA. Like the rat, hamster plasma contains an inhibitor(s) of LTA; the level of the inhibitor activity in d greater than 1.21 g/ml plasma was similar in normal and hyperlipoproteinemic hamsters. Hypertriglyceridemia in sucrose-fed hamsters did not affect LTA, cholesteryl ester transfer or the plasma level of HDL-CE. However, a comparable degree of hypercholesterolemia was associated with a 122% increase in plasma d greater than 1.21 LTA and a 63% increase in the fractional rate of [3H]CE transfer from HDL to lower density lipoproteins in plasma. Cholesterol feeding in hamsters was associated with increased plasma levels of LDL-cholesterol and, to a lesser extent, with VLDL- and IDL-cholesterol.

Animals↗

PubMed2006

An outcome analysis of patients transferred to a regional burn center: transfer status does not impact survival.

BACKGROUND: Optimal burn care is provided at specialized burn centers. Given the geographic location of these centers, many burn patients receive initial treatment at local emergency departments prior to transfer. The purpose of this study was to determine whether patients transferred from other facilities have worse outcomes than those admitted directly from the field. STUDY DESIGN: A retrospective cohort study was performed comparing the outcomes of patients admitted to our burn center directly from the field with patients requiring transfer from a preliminary care facility. The outcomes of interest were mortality, length of stay, length of stay/TBSA burned, number of operations and hospital charges. Poisson regression or Cox proportional hazards model was used to evaluate differences in outcomes after adjusting for potential confounders. RESULTS: From 2000 to 2003 a total of 1877 patients were admitted to our burn center and 953 (51%) were transferred from a preliminary care facility. No difference (p<0.05) was found in length of stay, number of operations, hospital charges and mortality between the two cohorts. CONCLUSIONS: This study demonstrates that patients transferred to a regional burn center from local hospitals have equivalent mortality, length of stay and hospital charges as those admitted directly from the field.

Adolescent↗

PubMed2005

Effectiveness of two-step (consecutive) embryo transfer in patients who have two embryos on day 2: comparison with cleavage-stage embryo transfer.

OBJECTIVE: To evaluate the effectiveness, for patients who have only two embryos on day 2, of a two-step (consecutive) embryo transfer (ET) procedure in which a cleaved embryo is transferred on day 2 and a single blastocyst is transferred on day 5. DESIGN: Observational comparative study. SETTING: Private IVF clinic. PATIENT(S): Ninety two-step ET cycles were performed in patients who had two embryos on day 2 (two-step group). Ninety day-2 ET cycles were performed in age- and infertility-matched patients who had two embryos on day 2 (control group). INTERVENTION(S): Cleaved-ET, extended culture of one embryo, and a second transfer of a blastocyst. MAIN OUTCOME MEASURE(S): Implantation and pregnancy rates. RESULT(S): The pregnancy and implantation rates in the two-step group (respectively 33.3% and 17.2%) were significantly higher than those in the control group (18.9% and 9.4%). Thirty-nine of the patients in the two-step group (43.3%) could not proceed to the second step of ET because no viable blastocyst could be obtained, but four of them conceived anyway. CONCLUSION(S): Taking advantage of both day-2 ET and blastocyst transfer, two-step ET may be an effective option for ET in patients who have an insufficient number of embryos.

Adult↗

PubMed2004

Treatment of acute myocardial infarction by hepatocyte growth factor gene transfer: the first demonstration of myocardial transfer of a "functional" gene using ultrasonic microbubble destruction.

OBJECTIVES: We examined whether ultrasonic microbubble destruction (US/MB) enables therapeutic myocardial gene transfer of hepatocyte growth factor (HGF) for acute myocardial infarction (MI). BACKGROUND: Hepatocyte growth factor gene transfer provides cardioprotective effects in MI, which requires direct intramyocardial injection or special vectors. Although US/MB was used in myocardial gene transfer, its feasibility in transfer of a therapeutic gene with non-viral vector remains unknown. METHODS: In a rat model of acute MI, naked plasmid (pVaxl) encoding human HGF (1,500 microg) was infused into the left ventricular (LV) chamber during US/MB (HGF-US/MB) or insonation only (HGF-US) or alone (HGF-alone), while control MI rats received empty pVaxl during US/MB (pVaxl-US/MB). For US/MB, transthoracic intermittent insonation with a diagnostic transducer (1.3 MHz) was performed for 2 min at a peak negative pressure of -2,160 kPa during intravenous 20% Optison. RESULTS: Baseline risk area was comparable among the groups. Immunohistology seven days after treatment revealed significant myocardial expression of HGF protein only in HGF-US/MB. At three weeks, LV weight in HGF-US/MB (0.89 +/- 0.03 g) was significantly lower than those in HGF-alone (1.09 +/- 0.08 g), HGF-US (1.04 +/- 0.07 g), and pVaxl-US/MB (1.04 +/- 0.05 g). Moreover, scar size was significantly smaller (16 +/- 6% vs. 39 +/- 5%, 41 +/- 6%, and 40 +/- 4% of total myocardial circumferential length, respectively), while capillary density (49 +/- 8 vs. 34 +/- 5, 37 +/- 6, and 36 +/- 4 capillaries/high-power field, respectively) and arterial density (37 +/- 7 vs. 15 +/- 9, 18 +/- 4, and 14 +/- 11 arterioles/high-power field, respectively) in the risk area were higher in HGF-US/MB than the other groups. CONCLUSIONS: Ultrasound-mediated microbubble destruction may enable myocardial HGF gene transfer with systemic administration of naked plasmid, which enhances angiogenesis, limits infarction size, and prevents LV remodeling after MI.

Animals↗