Evaluation of the homing of human CD34+ cells in mouse bone marrow using clinical MR imaging

There have been several reports using various superparamagnetic iron oxide (SPIO) nanoparticles to label mammalian cells for monitoring their temporal and spatial migration in vivo by Magnetic Resonance Imaging (MRI). The purpose of this study was to evaluate the efficiency of labeling cells using two commercially available FDA-approved agents: ferumoxide, a suspension of dextran-coated SPIO used as an MRI contrast agent and protamine sulfate used ex vivo as a cationic transfection agent to evaluate the use of clinical 1.5 Tesla magnetic resonance imaging equipment in showing the in vivo homing of iron oxide-labeled human CD34+ cells in irradiated mouse. After labeling human Hematopoietic (CD34+) stem cells with ferumoxide-protamine sulfate complex (FE-Pro), cellular toxicity, functional capacity and quantitative cellular iron incorporation were determined. FE-Pro labeled cells demonstrated neither short or long-term toxicity nor changes in colonogenic assay of the stem cells and their phenotype when compared with unlabeled cells. Efficient labeling with FE-Pro was observed with iron content per cell varying between 1.91 +/- 0.1 pg for CD34+ cells with 100% of cells labeled. After irradiation, Female Balb/c mice underwent MR imaging before and 12, 24, 48 and 72 h after intravenous injection of 0.5-1.5 x 10(7) labeled CD34+ cells. A significant decrease in MR signal intensity was observed in bone marrow at 24 and 48 h after injection. Our observations confirm that efficient labeling of cells with appropriate contrast agents should facilitate the translation of this method to clinical trials for evaluating the trafficking of infused or transplanted cells by MR Imaging.

Characterization of Transferrin-Modified Procationic-Liposome Protamine-DNA Complexes

We developed a novel transferrin modified non-viral gene delivery system, transferrin-modified procationic-liposome-protamine-DNA complexes (Tf-PLPD) and investigated its characteristics. Blank procationic liposomes were prepared using the film dispersion filter method. Protamine was used to condense plasmid DNA to form protamine-DNA complexes and the complexes were further incubated with blank procationic liposomes to form PLPD. Transferrin was adsorbed onto the surface of PLPD via an electrostatic interaction, and thus Tf-PLPD was produced. Characteristics such as stability in rat serum, morphology, average particle size, zeta potential, and transfection efficiency in HepG2 cells were further investigated. The results indicated that the procationic liposomes remained stable in rat serum for 24 h. Tf-PLPD protected plasmid DNA from enzymatic degradation even after lyophilization. The size distribution of Tf-PLPD was in the range of 240+/-12 nm and the zeta potential was -24.10+/-2.5 mV (n=3), respectively. The transfection efficiencies of Tf-PLPD were 24.26+/-2.6 mU beta-galactosidase/mg protein. Lyophilization and the presence of serum did not affect the transfectivity of Tf-PLPD and the procationic liposomes also had low cytotoxicity to cells.

In vivo magnetic resonance imaging of dendritic cell migration into the draining lymph nodes of mice

Dendritic cell (DC) migration into the draining lymph nodes is critical for T cell priming. Here, we show that magnetic resonance imaging (MRI) can be used to visualize DC migration in vivo. We combined clinically approved small particles of iron oxide (SPIO) with protamine sulfate to achieve efficient uptake by murine bone marrow-derived DC. SPIO-DC were largely unaltered and after injection into the footpads of mice, they migrated into the T cell areas of the draining lymph nodes, which could be visualized by MRI. Distinct MRI signal reduction patterns correlated with the detection of SPIO-DC mainly within Thy-1.2+ B220- T cell areas, as confirmed by iron staining and immunohistology. Clear signal reduction patterns could still be observed with 1x10(6) injected SPIO-DC at high resolution, resulting in the detection of about 2000 DC. Control injections of homing-incompetent SPIO-DC derived from CCR7-/- mice or SPIO alone did not reach the T cell areas. Taken together, the results demonstrate that clinically approved contrast agents allow the non-invasive visualization of DC migration into the draining lymph node by MRI in vivo at high resolution. This protocol therefore also allows dynamic imaging of immune responses and MRI-based tracking of human DC in patients.

Defoliation and Plasmid Delivery with Layer-by-Layer Coated Colloids

The uptake of polyelectrolyte multilayer coated colloids into cells, subsequent defoliation and plasmid delivery was studied by means of confocal microscopy and flow cytometry. Silica particles coated layer-wise with protamine and dextran sulfate were given to HEK 293T cells. Optimum uptake was found with protamine as the top layer. The particle uptake likely follows an non-receptor-mediated endocytotic pathway. Defoliation of polyelectrolyte multilayer coated particles within cells was demonstrated by the release of incorporated plasmids as indicated by the expression of plasmid encoded proteins using the enhanced green fluorescence proteine (pEGFP-C1) plasmid and a red fluorescence protein (pDsRed1-N1) plasmid. This proves, together with the direct observation of fluorescent layer debris, the defoliation of coated particles and the release of layer components into the cytoplasm. Particle uptake and GFP expression.

RNA-Interference Effectors and Their Delivery

RNA-interference, the mechanism by which the expression of a specific protein can be reduced or eliminated, has emerged as a potential way to treat disease. RNA-interference effectors, such as small interfering RNA and small hairpin RNA, are double-stranded nucleic acid sequences expressly designed to have homology to sections of the target protein's mRNA, and when present in the cytosol trigger hydrolysis of the mRNA through the RNA-interference pathway. Because RNA-interference effectors are macromolecular and typically polyanionic, their efficacy is poor when not accompanied by a delivery vehicle. This review outlines the RNA-interference mechanism and discusses the delivery of RNA-interference effectors, with an emphasis on synthetic polymer-based delivery systems.

Strong mucosal and systemic immunities induced by nasal immunization with anthrax protective antigen protein incorporated in liposome-protamine-DNA particles

PURPOSE

The very lengthy and complicated dosing schedule of the current anthrax vaccine adsorbed, which was licensed in the USA for the prevention of cutaneous anthrax infection, calls for the development of an efficacious and easily administrable vaccine to prevent against the most lethal form of anthrax infection, the inhalation anthrax. We propose to develop a nasal anthrax vaccine using anthrax protective antigen (PA) protein carried by liposome-protamine-DNA (LPD) particles.

METHODS

PA was incorporated in LPD particles and nasally dosed to mice. The resulting PA-specific immune response and lethal toxin neutralization activity were measured.

RESULTS

Mice nasally immunized with PA incorporated into LPD particles developed both systemic and mucosal anti-PA responses. The anti-PA immunities induced included the production of anti-PA antibodies (IgG and IgM in the serum and IgA in nasal and lung mucosal secretions) and the proliferation of splenocytes after in vitro stimulation. The anti-PA IgG subtype induced was mainly IgG1. Finally, anthrax lethal toxin neutralization activity was detected both in the serum and in the mucosal secretions.

CONCLUSIONS

The anti-PA immune response induced by nasal PA incorporated in LPD was comparable to that induced by nasal PA adjuvanted with cholera toxin or subcutaneously injected PA adjuvanted with aluminum hydroxide.

Follicle-Like Model by Granulosa Cell Encapsulation in a Barium Alginate–Protamine Membrane

Granulosa cells from bovine and porcine ovaries were cultured either in monolayer or in follicle-like barium alginate capsules for 6 days. Morphological investigation by electron scanning microscopy indicated that culture in a three-dimensional (3D) system allows self-organization of spherical-polyhedral shape cells. The luteinization index (progesterone:17beta-estradiol ratio) was significantly higher for monolayer cells than for the 3D cell culture system, confirming the results of morphological analysis and indicating more physiological growth. The encapsulated 3D culture system appears to be a promising way of obtaining in vitro maturation and development of follicles and oocytes.

Reproducibility and variability in the action of injected insulin

Insulin-treated patients are generally taught to adapt their doses of insulin according to the glycemic level obtained during self-tests. They usually adhere to medical recommendations, but are often confused by the results, which may not correspond to expectations. Patients have to contend with variability and a certain degree of unpredictability in the results. Our knowledge of the factors involved in this variability is often imprecise. We review here the factors depending on the preparation of insulin itself, not only with regard to its crystallization but also the speed at which the hexamers dissociate into dimers. The development of fast and slow-acting analogues is discussed along with their value in improving glycemic predictability. In addition to these factors, we mention those stemming from the injection technique itself, which are directly related to the instructions given to the patients. For crystallized insulin preparations, shaking the bottle is an important element that the development of slow-acting analogues should eliminate, but the time lapse before withdrawing the needle, the anatomical site of the insulin injection, and the depth of the injection are also factors for variability. Greater predictability in the action of insulin will be obtained from a combination of progress in manufacturing procedures and better patient education.

An Experimental Study of Apico-Aortic Valved Conduit (AAVC) for Surgical Treatment of Aortic Stenosis in Dogs

A new valved conduit was developed using a canine aortic valve. The bioprosthetic valve was fixed with glutaraldehyde and epoxy compound (Denacol-EX313/810). A vascular graft composed of ultra-fine polyester fiber (10 mm in diameter, 200 mm in length) was used. Four dogs underwent apico-aortic valved conduit (AAVC) implantation and aortic banding (bypass group, BG), while another 4 dogs underwent aortic banding without AAVC implantation (control group, CG). Cardiac catheterization and angiocardiography were performed for assessment of hemodynamics 2 weeks and 6 months after surgery. Left ventricular systolic pressure, left ventricular end-diastolic pressure and the left ventricular-aortic pressure gradient differed significantly (P<0.01) between the BG and CG dogs. Left ventricular angiocardiography showed patency of the valved conduit in all the BG dogs. Echocardiography was performed before and 2, 4 and 6 months after surgery, and showed that while pressure overload caused concentric myocardial hypertrophy in the CG dogs, the left ventricle dilated eccentrically in the BG dogs. Furthermore, relief of left ventricular pressure overload by AAVC was maintained.

In vivo transfection of NF-kappaB decoy oligodeoxynucleotides attenuate renal ischemia/reperfusion injury in rats

BACKGROUND

Ischemic acute renal failure (ARF) is a common and often fatal condition characterized by tubular epithelial cell necrosis and marked monocyte infiltration. Inflammatory mechanisms, including cell adhesion, cell infiltration, and cytokine production, are involved. These processes are thought to be directly or indirectly regulated by nuclear factor kappaB (NF-kappaB). Targeted of NF-kappaB might ameliorate ischemia/reperfusion (I/R) injury by inhibiting the production of genes that involved in ischemic ARF. The objective of the present study was to evaluate the effect of NF-kappaB decoy oligodeoxynucleotides (ODN) in experimental rat ischemic ARF.

METHODS

Ischemic ARF was induced by left renal artery clamping for 60 minutes, while the right kidney was being removed in female Sprague-Dawley rats. The effect of cationic liposome-protamine-NF-kappaB decoy ODN was evaluated after infusion into the kidney via the renal artery before clamping. After 24 hours of reperfusion, we then assessed morphologic and functional parameters, NF-kappaB/DNA binding activity, monocyte/macrophage (M/MPhi) infiltration, and gene expression in I/R kidney.

RESULTS

After 24 hours of reperfusion, compared with sham-operated animals, serum creatinine and blood urea nitrogen (BUN) levels in ischemic ARF animals were increased about 10-fold and fivefold respectively. (255.67 +/- 34.48 micromol/L vs. 25.33 +/- 2.23 micromol/L and 43.47 +/- 5.50 mmol/L vs. 8.45 +/- 0.43 mmol/L, P < 0.001), NF-kappaB/DNA binding activity was markedly elevated [median value was 1.75 vs. 0.15 relative density unit (RDU), P < 0.005]. NF-kappaB decoy ODN treatment reduced the elevation of serum creatinine level by 70% (79.17 +/- 8.64 micromol/L vs. 255.67 +/- 34.48 micromol/L, P < 0.01), BUN level by 40% (28.33 +/- 4.86 mmol/L vs. 43.47 +/- 5.50 mmol/L, P= NS), and almost abolished the NF-kappaB activation compared with levels observed in sham-operated rats (median value was 0.25 vs. 1.9 RDU, P < 0.005). Furthermore, NF-kappaB decoy ODN pretreatment prevented the occurrence of tubular necrosis and reduced the renal tubular damage scores markedly (1.85 +/- 0.06 vs. 3.63 +/- 0.06 scores, P < 0.01). In addition, M/MPhi infiltration was obviously suppressed (9.77 +/- 1.19 cells/hpf vs. 29.22 +/- 1.94 cells/hpf, P < 0.01), Moreover, results of reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry showed the up-regulation of monocyte chemoattractant protein-1 (MCP-1) and intercellular adhesion molecule-1 (ICAM-1) was greatly decreased, inducible nitric oxide synthase (iNOS) and endothelin-1 (ET-1) expression were also reduced, approaching levels observed in sham-operated animals. The data suggest that NF-kappaB decoy ODN treatment protects renal tissue from the effects of I/R injury and thus reduces the severity of ARF.

CONCLUSION

These experiments demonstrated that NF-kappaB plays a critical role in renal I/R injury by reducing a series of inflammatory genes. NF-kappaB decoy ODN treatment reduces the renal dysfunction and damage associated with ischemic ARF. Therefore, in vivo transfection of NF-kappaB decoy ODN provides a new therapeutic strategy for ischemic ARF.

[Preparation of lipid-protamine-DNA complexes and evaluation of their transfection efficiencies in vitro]

AIM

To develop a novel non-viral gene delivery systems lipid-polycation-DNA complexes (LPD) and investigate their transfection efficiencies in vitro.

METHODS

LPD were prepared as follows by first mixing the plasmid DNA and protamine together, then the resulted polyplexes were incubated for 10 min at room temperature, followed by addition of preformed cationic liposomes. The morphology of LPD was observed by transmission electron microscopy. The diameter and surface charge of LPD were measured by photon correlation spectroscopy (PCS). The nuclease protection ability of LPD was evaluated by agarose gel electrophoresis. Estimation of transfection efficiency was performed by galactosidase assay in Chang, HepG2 and SMMC-7721 cells.

RESULTS

The average diameter and the zeta potential of LPD were 143.5 nm and 32.6 mV, respectively. LPD could protect the plasmid DNA from nuclease degradation after 2 hours incubation at 37 degrees C while the naked DNA degraded rapidly. The average transfection efficiencies were (69 +/- 6)%, (43 +/- 7)% and (96.2 +/- 1.8)% in Chang cells, HepG2 cells and SMMC-7721 cells respectively.

CONCLUSION

LPD could be prepared easily with small particle sizes and high transfection activities. LPD may be good non-viral vectors for applications in gene delivery.

In vivo efficacy of folate-targeted lipid-protamine-DNA (LPD-PEG-Folate) complexes in an immunocompetent syngeneic model for breast adenocarcinoma

Gene therapy utilizing lipid-based delivery systems holds tremendous promise for the treatment of cancer. However, due to the potential adverse inflammatory and/or immune effects upon systemic administration, treatments thus far have been predominantly limited to intratumoral or regional treatment. Previous studies from our group have demonstrated the antitumor efficacy of systemically administered, folate-targeted, lipid-protamine-DNA complexes (LPD-PEG-Folate) against breast cancer using an immunodeficient xenogenic murine model. In the current study, the antitumor efficacy of LPD-PEG-Folate in a syngeneic, immune competent, murine model of breast cancer was examined. In this model, the potential inflammatory or immune responses and their effects on systemic delivery can be addressed. The 410.4 murine breast adenocarcinoma cell line was initially evaluated in vitro for its interactions with LPD-PEG-Folate and control LPD-PEG formulations. Utilizing fluorescently labeled formulations and fluorescence-activated cell sorting (FACS) analysis, a 1.6-fold enhancement of binding and internalization of LPD-PEG-Folate over LPD-PEG formulations was observed, suggestive of specific receptor interaction. Increased binding was manifested as 5-26-fold increases in luciferase gene expression in 410.4 cell transfection when comparing LPD-PEG-Folate to LPD-PEG. Moreover, in vivo treatment of 410.4 breast tumors in BALB/c mice with i.v. injected LPD-PEG-Folate delivering the HSV-1 thymidine kinase (TK) gene, in combination with gancyclovir treatment, resulted in a significant reduction in mean tumor volume (260.1 mm3) compared to the LPD-PEG-TK (914.1 mm3), as well as the vehicle (749.7 mm3) and untreated (825.3 mm3) control groups (day 25, P<.019). In addition to a reduced tumor volume, LPD-PEG-Folate-TK treatment also increased median survival from 25 days in the nontargeted LPD-PEG-TK groups to 31 days (P=.0011), which correlated with the termination of treatment. Together, these results demonstrate that in the context of a fully functional immune system, LPD-PEG-Folate-TK treatment possesses significant specific antitumor efficacy and the potential for further preclinical development.

Boar semen controlled-delivery system: morphological investigation and in vitro fertilization test

A technology for encapsulation of swine semen in barium alginate and protamine alginate has recently been proposed for the controlled release of the spermatozoa, thus reducing the number of instrumental inseminations required. Controlled-release capsules containing swine spermatozoa were prepared by adding saturated BaCl2 solution to ejaculate and dropping the resulting suspension into a sodium alginate solution, leading to the formation of barium alginate capsules. A second type of capsule was obtained by cross-linking the barium alginate with protamine sulfate. Two types of membrane were thus obtained: barium alginate gel and a protamine cross-linked alginate membrane. Morphological (scanning electron microscopy and transmission electron microscopy), functional (motility, membrane integrity and in vitro fertilization test) and technological (capsule structure and weight) approaches were used to characterize the encapsulated spermatozoa and the controlled-delivery system. No differences in terms of morphological and functional characteristics (acrosome integrity and spermatozoa motility) between free and encapsulated semen were found. The technological process did not compromise in vitro fertilization potency of the spermatazoa, although seasonal variability was found. The capsule weight was related to either the pH of the semen or the season. This study represents the starting point for the development of further investigations into the storage and release kinetics of cells from the capsules and for the development of an in vivo fertilization protocol.

Lipid-protamine-DNA-mediated antigen delivery to antigen-presenting cells results in enhanced anti-tumor immune responses

Vaccination with antigenic peptides encoding tumor antigens has the potential to be an effective treatment for cancer. To induce tumor-specific cellular immune responses, a peptide antigen must be presented by antigen-presenting cells (APCs) to T-cells in the lymphatic tissues. Effective in vivo delivery of peptide antigens to APCs has been problematic. Here we use a model antigen from the HPV16 E7 protein to formulate LPD/E7 particles that upon iv administration are internalized by CD11c(+) and CD11b(+) cells in the marginal zone of the spleen. Either iv or sc vaccination with LPD/E7 particles induces E7-specific CTL responses stronger than those obtained using previously described liposome/peptide strategies and prevents the establishment of E7-expressing tumors. Furthermore, the administration of LPD/E7 particles to tumor-bearing mice caused complete tumor regression in 100% of the treated animals. Based on these studies, the entrapment of peptide antigens inside LPD particles may be an effective and generally applicable strategy for the enhancement of peptide vaccine potency.

The role of chromatin damage in nickel-induced carcinogenesis. A review of recent developments

Over the last years, we have been testing a hypothesis that molecular mechanisms of nickel-induced carcinogenesis include interactions of this metal with major chromatin components; DNA, histones, and protamines. Our investigations using synthetic peptide models have resulted in identification of nickel-binding sites in core histones H3 and H2A and in protamine P2. These are: the internal -Cys110-AIH- motif in histone H3: the C-terminal-E121-SHHKAKGK "tail" motif in histone H2A; and the N-terminal RTH- motif in protamine P2. Ni(II) bound to the H3 and P2 motifs enhances oxidative DNA base damage by H2O2. In contrast, Ni(II) complex with the H2A "tail" is not redox active. However, at pH 7.4, it undergoes hydrolysis yielding a new complex, Ni(II)-SHHKAKGK, reactive with H2O2 and capable of mediating DNA oxidation. The "tail" cutting of H2A has also been observed in cells cultured with Ni(II). In Ni(II) complex with the protamine P2 peptides, H2O2 causes degradation of the metal-binding His3 and the distant Tyr8 residues. This site-specificity results from a long-range structuring effect of Ni(II) on its protamine ligand. In conclusion, Ni(II) binding to some chromatin proteins in somatic and sperm cells may result in oxidative and structural damage to the proteins and DNA. These effects may alter the fidelity of DNA replication and gene expression and thus facilitate carcinogenesis, including paternally-mediated cancer in the progeny.

[Successful management after cardiopulmonary bypass without administration of protamine in a patient with severe food allergy--beneficial result with the use of heparin-coated bypass circuit]

We experienced the anesthetic management for cardiac surgery without the administration of protamine in a patient with severe food allergy. The patient, a 15-year-old boy, who had been avoiding many kinds of food including fish due to severe food allergy, received a correction of ventricular septal defect under cardiopulmonary bypass (CPB). To detect intraoperative drugs, including protamine, which might induce allergic reaction, we performed intradermal tests and prick tests. We used heparin-coated bypass circuit to minimize the amount of heparin necessary for anticoagulation during CPB. After CPB, hemostasis was achieved without the administration of protamine, and the patient received neither transfusion nor blood product throughout the perioperative period. Avoidance of protamine is advisable if the patient is allergic to food especially fish. The use of heparin-coated bypass circuit should be considered to establish hemostasis without protamine after CPB and to reduce blood products.

Increased receptor-mediated gene delivery to the liver by protamine-enhanced-asialofetuin-lipoplexes

A novel lipidic vector composed of DOTAP/Chol liposomes, asialofetuin (AF), protamine sulfate and DNA has been developed. The resulting protamine-AF-lipoplexes improved significantly the levels of gene expression in cultured cells and in the liver upon i.v. administration. Lipoplexes containing the optimal amount of AF (1 microg/microg DNA) showed a 16-fold higher transfection activity in HepG2 cells than non-targeted (plain) complexes. The uptake by cells having asialoglycoprotein receptors (ASGPr) on their plasma membrane was decreased by the addition of free AF, indicating that AF-lipoplexes were taken up specifically by cells via ASGPr-mediated endocytosis. Results from transfections performed in cells defective in ASGPr, ie HeLa cells, confirmed this mechanism. By addition of the condensing peptide, protamine sulfate, smaller complexes were obtained, which enhanced even more the uptake of AF-complexes in HepG2 cells and in the liver. The optimal amount of protamine was 0.4 microg/mcirog DNA, and gene expression was about 5-fold over that obtained with AF-lipoplexes in the absence of the peptide, and 75-fold higher than that with plain conventional lipoplexes. Protamine-AF-lipoplexes increased by a factor of 12 luciferase gene expression in the liver of mice administered systemically via the tail vein, compared to plain complexes. In summary, our findings extend the scope of previous studies where AF-lipoplexes were used to introduce DNA into hepatocytes. The combination of targeting and protamine condensation obviated the need for partial hepatectomy, commonly required to obtain efficient gene delivery in this organ. Since protamine sulfate has been proven to be non-toxic in humans, the novel liver-specific vector described here may be useful for the delivery of clinically important genes to this organ.

Enhanced cytosolic delivery of plasmid DNA by a sulfhydryl-activatable listeriolysin O/protamine conjugate utilizing cellular reducing potential

Listeriolysin O (LLO), a sulfhydryl-activated pore-forming protein from Listeria monocytogenes, was tested and utilized for promoting plasmid DNA (pDNA) delivery into the cytosol of cells in culture. To render pDNA-complexing capability to LLO, the unique cysteine 484 of LLO was conjugated to polycationic peptide protamine (PN) at a 1:1 molar ratio through a reversible, endosome-labile disulfide bond. The sulfhydryl-oxidized LLO construct, LLO-s-s-PN, completely lacked its pore-forming activity, yet regained its original activity upon reduction. The enhanced cytosolic delivery using this construct therefore relies on the requisite reduction of the disulfide bond in LLO-s-s-PN by endogenous cellular reducing capacity. Condensed PN/pDNA complexes incorporating LLO-s-s-PN were tested for their enhanced gene delivery capability monitoring reporter gene expression in HEK293, RAW264.7, P388D1 cell lines and bone-marrow-derived macrophages in the presence of serum. Dramatic enhancement was observed for all tested complexes with varying weight ratios. The effect was most prominent at 0.64-0.80 (w/w) of PN/pDNA upon replacing 1-4% of PN with LLO-s-s-PN, resulting in approximately three orders of magnitude higher luciferase expression compared to PN/pDNA without apparent toxicity. These results demonstrate that incorporation of endosomolytic LLO into pDNA delivery systems in a controlled fashion is a promising approach of enhancing delivery into the cytosol of target cells in gene delivery strategies.

Agreements between the prothrombin times of blood treated In Vitro with heparinase during cardiopulmonary bypass (CPB) and blood sampled after CPB and systemic protamine

The prothrombin time (PT) is useful for identifying coagulation factor deficits after cardiopulmonary bypass (CPB). However, long processing times and the need for fresh frozen plasma (FFP) to be thawed cause delays in factor replacement. We hypothesized that, by treating with heparinase, blood sampled toward the end of CPB can provide PT results that help to determine the requirement for FFP after CPB. Laboratory delays can be eliminated with point-of-care monitors. We studied 158 adults undergoing nonemergent cardiac surgery. Blood taken before separation from CPB was mixed with heparinase, and PT was measured in the laboratory with a HemoTec timer. Agreements between these results and laboratory measurements of blood taken after systemic protamine were compared by using Bland and Altman plots with the threshold of +/-1.0 s. We found that the laboratory PT measurements during CPB versus after CPB were compara-ble, but the limits of agreement exceeded these thresholds. Similarly, there was unsatisfactory agreement between the HemoTec and laboratory PT results measured before, during, and after CPB. For each PT measured during CPB, the corresponding confidence interval for the postprotamine PT was calculated. During CPB, a laboratory PT of < or =16 s or > or =18 s suggests a > or =83% or > or =93% probability of not requiring or potentially requiring, respectively, FFP after CPB. We conclude that the majority of PT measurements obtained from blood taken before weaning from CPB and treated in vitro with heparinase was associated with a high probability of whether or not FFP would be needed after CPB.

IMPLICATIONS

Coagulation dysfunction after cardiopulmonary bypass may contribute to bleeding. Obtaining coagulation tests and fresh frozen plasma requires time and delays treatment in patients who need fresh frozen plasma. We have devised a technique to provide early estimation of postbypass coagulation status.

An ACF1-ISWI chromatin-remodeling complex is required for DNA replication through heterochromatin

The mechanism by which the eukaryotic DNA-replication machinery penetrates condensed chromatin structures to replicate the underlying DNA is poorly understood. Here we provide evidence that an ACF1-ISWI chromatin-remodeling complex is required for replication through heterochromatin in mammalian cells. ACF1 (ATP-utilizing chromatin assembly and remodeling factor 1) and an ISWI isoform, SNF2H (sucrose nonfermenting-2 homolog), become specifically enriched in replicating pericentromeric heterochromatin. RNAi-mediated depletion of ACF1 specifically impairs the replication of pericentromeric heterochromatin. Accordingly, depletion of ACF1 causes a delay in cell-cycle progression through the late stages of S phase. In vivo depletion of SNF2H slows the progression of DNA replication throughout S phase, indicating a functional overlap with ACF1. Decondensing the heterochromatin with 5-aza-2-deoxycytidine reverses the effects of ACF1 and SNF2H depletion. Expression of an ACF1 mutant that cannot interact with SNF2H also interferes with replication of condensed chromatin. Our data suggest that an ACF1-SNF2H complex is part of a dedicated mechanism that enables DNA replication through highly condensed regions of chromatin.

Rapid-SF: a rapid whole-blood screen for soluble fibrin monomer

Thrombosis accounts for a high proportion of disability and death in the West. Although soluble fibrin (SF) assays have been shown to be good predictors of thrombosis, current quantitative assays are too complex or lengthy to provide timely results, while simpler methods are qualitative and lack sensitivity. We here describe a rapid, new, protamine-based whole-blood screening method for SF which is quantitative and suitable for point-of-care use. Citrated whole blood is mixed with reagent under controlled conditions and the time until development of an SF precipitate is measured. Negative samples remain precipitate-free for 300 seconds. Strongly positive samples develop precipitate in as little as 10 seconds. SF times are mathematically converted to arbitrary SF units (SFU). This Rapid-SF test provides a simple and reliable means of detecting the presence of SF, and is well-suited for whole-blood rapid screening in the emergency department, operating room or clinic.