Zeta potentials of the rare earth element fluorcarbonate minerals focusing on bastnäsite and parisite.

Rare earth elements (REE) are critical to a wide range of technologies ranging from mobile phones to wind turbines. Processing and extraction of REE minerals from ore bodies is, however, both challenging and relatively poorly understood, as the majority of deposits contain only limited enrichment of REEs. An improved understanding of the surface properties of the minerals is important in informing and optimising their processing, in particular for separation by froth flotation. The measurement of zeta potential can be used to extract information regarding the electrical double layer, and hence surface properties of these minerals. There are over 34 REE fluorcarbonate minerals currently identified, however bastnäsite, synchysite and parisite are of most economic importance. Bastnäsite-(Ce), the most common REE fluorcarbonate, supplies over 50% of the world's REE. Previous studies of bastnäsite have showed a wide range of surface behaviour, with the iso-electric point (IEP), being measured between pH values of 4.6 and 9.3. In contrast, no values of IEP have been reported for parisite or synchysite. In this work, we review previous studies of the zeta potentials of bastnäsite to investigate the effects of different methodologies and sample preparation. In addition, measurements of zeta potentials of parisite under water, collector and supernatant conditions were conducted, the first to be reported. These results showed an iso-electric point for parisite of 5.6 under water, with a shift to a more negative zeta potential with both collector (hydroxamic and fatty acids) and supernatant conditions. The IEP with collectors and supernatant was <3.5. As zeta potential measurements in the presence of reagents and supernatants are the most rigorous way of determining the efficiency of a flotation reagent, the agreement between parisite zeta potentials obtained here and previous work on bastnäsite suggests that parisite may be processed using similar reagent schemes to bastnäsite. This is important for future processing of REE deposits, comprising of more complex REE mineralogy.

Long-term correction of hemophilia A mice following lentiviral mediated delivery of an optimized canine factor VIII gene.

Current therapies for hemophilia A include frequent prophylactic or on-demand intravenous factor treatments which are costly, inconvenient and may lead to inhibitor formation. Viral vector delivery of factor VIII (FVIII) cDNA has the potential to alleviate the debilitating clotting defects. Lentiviral-based vectors delivered to murine models of hemophilia A mediate phenotypic correction. However, a limitation of lentiviral-mediated FVIII delivery is inefficient transduction of target cells. Here, we engineer a feline immunodeficiency virus (FIV) -based lentiviral vector pseudotyped with the baculovirus GP64 envelope glycoprotein to mediate efficient gene transfer to mouse hepatocytes. In anticipation of future studies in FVIII-deficient dogs, we investigated the efficacy of FIV-delivered canine FVIII (cFVIII). Codon-optimization of the cFVIII sequence increased activity and decreased blood loss as compared to the native sequence. Further, we compared a standard B-domain deleted FVIII cDNA to a cDNA including 256 amino acids of the B-domain with 11 potential asparagine-linked oligosaccharide linkages. Restoring a partial B-domain resulted in modest reduction of endoplasmic reticulum (ER) stress markers. Importantly, our optimized vectors achieved wild-type levels of phenotypic correction with minimal inhibitor formation. These studies provide insights into optimal design of a therapeutically relevant gene therapy vector for a devastating bleeding disorder.

Do anthropometric measures accurately reflect body composition in preterm infants?

BACKGROUND: Recent literature suggests that neonatal adiposity is predictive of later metabolic health, while neonatal lean mass is predictive of later cognitive function amongst preterm infants. Anthropometric indices that accurately reflect neonatal body composition could improve clinical care and aid future research, but their validity has not been systematically tested in preterm infants. OBJECTIVE: To determine the weight/length indices that best reflect neonatal body composition in preterm infants. METHODS: Weight and length were measured, and body composition (fat-free mass (FFM), fat mass (FM) and percent body fat (%BF)) was assessed using air-displacement plethysmography within 72 h of birth in 218 preterm infants. The best weight/length proxy for FFM, FM and %BF were those with the highest proportion variance explained (R2 ) and lowest root mean square error (RMSE) in linear regression models. RESULTS: Among all of the weight/length indices tested, weight/length2 was the best proxy for %BF, but nonetheless exhibited very low variance explained (R2 = 0.27) and high prediction error (RMSE = 3.5% fat). Body weight unadjusted for length was strongly associated with FFM (R2 = 0.97). CONCLUSIONS: No weight/length index accurately reflected %BF. Weight/length indices are not appropriate for assessment of relative adiposity in preterm infants near birth. What's known on this subject: Compared with term infants, preterm infants have increased fat mass and diminished fat-free mass upon hospital discharge. Early adiposity predicts later metabolic health, while early lean mass is predictive of later neurodevelopmental outcomes. Optimal anthropometric proxies for preterm body composition at birth are not established. WHAT THIS STUDY ADDS: Weight is an adequate surrogate for lean mass at birth in preterm infants. There are no weight/length indices that accurately reflect neonatal adiposity at birth.

PU.1 and the granulocyte- and macrophage colony-stimulating factor receptors play distinct roles in late-stage myeloid cell differentiation.

PU.1 is a hematopoietic cell-specific ets family transcription factor. Gene disruption of PU.1 results in a cell autonomous defect in hematopoietic progenitor cells that manifests as abnormal myeloid and B-lymphoid development. Of the myeloid lineages, no mature macrophages develop, and the neutrophils that develop are aberrantly and incompletely matured. One of the documented abnormalities of PU. 1 null (deficient) hematopoietic cells is a failure to express receptors for granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage (GM)-CSF, and M-CSF. To elucidate the roles of the myeloid growth factor receptors in myeloid cell differentiation, and to distinguish their role from that of PU.1, we have restored expression of the G- and M-CSF receptors in PU.1-deficient cells using retroviral vectors. We have similarly expressed PU.1 in these cells. Whereas expression of growth factor receptors merely allows a PU.1-deficient cell line to survive and grow in the relevant growth factor, expression of PU.1 enables the development of F4/80(+), Mac-1(+)/CD11b(+) macrophages, expression of gp91(phox) and generation of superoxide, and expression of secondary granule genes for neutrophil collagenase and gelatinase. These studies reinforce the idea that availability of PU.1 is crucial for normal myeloid development and clarify some of the molecular events in developing neutrophils and macrophages that are critically dependent on PU.1.

The resistance of retroviral vectors produced from human cells to serum inactivation in vivo and in vitro is primate species dependent.

The ability to deliver genes as therapeutics requires an understanding of the vector pharmacokinetics similar to that required for conventional drugs. A first question is the half-life of the vector in the bloodstream. Retroviral vectors produced in certain human cell lines differ from vectors produced in nonhuman cell lines in being substantially resistant to inactivation in vitro by human serum complement (F. L. Cosset, Y. Takeuchi, J. L. Battini, R. A. Weiss, and M. K. Collins, J. Virol. 69:7430-7436, 1995). Thus, use of human packaging cell lines (PCL) may produce vectors with longer half-lives, resulting in more-efficacious in vivo gene therapy. However, survival of human PCL-produced vectors in vivo following systemic administration has not been explored. In this investigation, the half-lives of retroviral vectors packaged by either canine D17 or human HT1080 PCL were measured in the bloodstreams of macaques and chimpanzees. Human PCL-produced vectors exhibited significantly higher concentrations of circulating biologically active vector at the earliest time points measured (>1, 000-fold in chimpanzees), as well as substantially extended half-lives, compared to canine PCL-produced vectors. In addition, the circulation half-life of human PCL-produced vector was longer in chimpanzees than in macaques. This was consistent with in vitro findings which demonstrated that primate serum inactivation of vector produced from human PCL increased with increasing phylogenetic distance from humans. These results establish that in vivo retroviral vector half-life correlates with in vitro resistance to complement. Furthermore, these findings should influence the choice of animal models used to evaluate retroviral-vector-based therapies.

Genetic immunization of chimpanzees chronically infected with the hepatitis B virus, using a recombinant retroviral vector encoding the hepatitis B virus core antigen.

Cytotoxic T lymphocyte (CTL) activity and CD4+ helper T cell responses to the hepatitis B virus (HBV) core antigen (HBcAg) have been implicated in clearance of acute and chronic HBV infections. We showed that intramuscular injections of a novel recombinant retroviral vector expressing an HBcAg-neomycin phosphotransferase II (HBc-NEO) fusion protein induces HBc/eAg-specific antibodies and CD4+ and CD8+ T cell responses in mice and rhesus monkeys. We have now immunized three chronically infected chimpanzees, each with 10(10) CFU of nonreplicating retroviral vector particles expressing the HBc-NEO fusion protein. Of two immunized chimpanzees examined for CTL responses, one developed HBcAg-specific CTLs and showed marginal, transient elevations of alanine aminotransferase (ALT) levels following injection. However, both chimpanzees remained positive for serum HBeAg, negative for anti-HBe antibody by conventional assays, and displayed no change in HBV viral load throughout the study. In contrast, the third chimpanzee exhibited a traditional seroconversion evidenced by a loss of serum HBeAg and the subsequent emergence of anti-HBe antibodies within 24 weeks after the first injection. Simultaneously, two transient ALT flares and a significant decrease in the serum HBV DNA levels were noted. Despite its limitations, the present study demonstrates (1) the safety of treatment with high titers of retroviral vector in chimpanzees, (2) the capability of a retroviral vector expressing HBcAg to stimulate immune responses in HBV chronic carrier chimpanzees, and (3) that retroviral vector immunization may be therapeutically beneficial in the treatment of chronic HBV infection.

Direct injection of a recombinant retroviral vector induces human immunodeficiency virus-specific immune responses in mice and nonhuman primates.

The cytotoxic T-lymphocyte (CTL) response plays an important role in controlling the severity and duration of viral infections. Immunization by direct in vivo administration of retroviral vector particles represents an efficient means of introducing and expressing genes and, subsequently, the proteins they encode in vivo in mammalian cells. In this manner foreign proteins can be provided to the endogenous, class I major histocompatibility complex antigen presentation pathway leading to CTL activation. A nonreplicating recombinant retroviral vector, encoding the human immunodeficiency virus type 1 (HIV-1) IIIB envelope and rev proteins, has been developed and examined for stimulation of immune responses in mouse, rhesus macaque, and baboon models. Animals were immunized by direct intramuscular injection of the retroviral vector particles. Vector-immunized mice, macaques, and baboons generated long-lived CD8+, major histocompatibility complex-restricted CTL responses that were HIV-1 protein specific. The CTL responses were found to be dependent on the ability of the retroviral vector to transduce cells. The vector also elicited HIV-1 envelope-specific antibody responses in mice and baboons. These studies demonstrate the ability of a retroviral vector encoding HIV-1 proteins to stimulate cellular and humoral immune responses and suggest that retrovector immunization may provide an effective means of inducing or augmenting CTL responses in HIV-1-infected individuals.

Koelliker on Cajal: translated excerpts from Erinnerungen aus meinem Leben.

Albert Koelliker was the foremost histologist of the late 1800s. Koelliker personally worked on many of the same issues as Santiago Ramón y Cajal and was well placed to provide a contemporary commentary on the reception of Cajal's ideas. We have translated selected excerpts from Koelliker's autobiography, Erinnerungen aus meinem Leben, which discuss the ideas of Cajal which were treated no differently than most present day hypotheses; they were disputed on logical, technical, and personal grounds.

Induction of HIV-specific CTL and antibody responses in mice using retroviral vector-transduced cells.

Recombinant retroviral vectors can efficiently transduce and express foreign genes in mammalian cells. We have examined the utility of retroviral vector-mediated gene transfer to deliver genes which encode human immunodeficiency virus type I (HIV) antigens capable of stimulating specific immune responses. Murine fibroblast cell lines were transduced with a nonreplicating murine retroviral vector carrying the gene encoding the HIV-IIIB envelope protein and were shown to express the gp160/120 protein. Mice immunized with syngeneic vector-transduced cells developed CD8+, class I major histocompatibility complex (MHC)-restricted cytotoxic T lymphocytes (CTL) specific for targets expressing the HIV envelope protein. The CTL also exhibited lytic activity on target cells coated with synthetic peptides derived from the gp120 V3 hypervariable region of both the HIV-IIIB and HIV(MN) isolates. Following adoptive transfer in a murine tumor model, these CTL were shown to be effective in vivo by their ability to eliminate established tumor cells expressing the HIV protein. Vector-transduced syngeneic cells were also capable of eliciting HIV envelope-specific antibody responses in immunized mice. Sera obtained from these mice were found to bind to the HIV-IIIB gp160 protein as well as a peptide-defined neutralizing antibody epitope contained within the V3 domain of gp120. These sera exhibited virus-neutralizing activity in that they markedly reduced the ability of HIV to infect and form syncytia of a human T-cell line. This is the first demonstration that cells transduced with a retroviral vector encoding the HIV-IIIB envelope protein are capable of inducing effective HIV-specific cellular and humoral immune responses in mice.

High activity of N-alpha-benzyloxycarbonyl-L-lysine thiobenzyl ester serine esterase and cytolytic perforin in cloned cell lines is not demonstrable in in-vivo-induced cytotoxic effector cells.

Recent observations have suggested striking similarities between complement-mediated and cell-mediated lysis. Both pathways share the terminal insertion of channels into target membranes, and unique esterases have been postulated to participate in the activation of cytolytic effector molecules. Since killer-specific esterases and channel-forming proteins can be demonstrated in in vitro cell lines, it is important to ascertain that the described esterase and channel-forming proteins are also present in killer cells from in vivo sources. Results presented here show that killer-cell-specific N alpha-benzyloxycarbonyl-L-lysine thiobenzyl ester serine esterase is induced in vitro concomitant with the sensitization of cytotoxic effector cells. In contrast, in-vivo-primed cytotoxic T cells or natural killer (NK) cells fail to express high levels of this enzyme. Assay of different cytotoxic effector cells reveals the presence of N alpha-benzyloxycarbonyl-L-lysine thiobenzyl ester serine esterase in clones with T killer and NK activity, but enzyme levels do not correlate with cytolytic activity nor does inhibition of esterase activity interfere with granule-mediated cell lysis. A similar result is seen with granule-mediated cytolytic activity. Cloned NK and T killer cell lines possess granules that are able to lyse erythrocyte targets. However, T killer cells sensitized in mixed lymphocyte culture or in vivo have no detectable cytotoxic granules. Cytotoxic granules are also not detected in NK cells isolated from animals.

Induction of bone marrow allograft rejection and hybrid resistance in nonresponder recipients by antibody: is there evidence for a dual receptor interaction in acute marrow graft rejection?

Acute marrow graft rejection in allogeneic or semiallogeneic donor-recipient mouse combinations has been suggested to be caused by natural killer (NK) cells. The unique in vitro specificity of NK cells for tumor cells, however, does not explain the specific rejection of bone marrow grafts by NK cells. Recent experiments have implicated antibody in marrow graft recipients as the specificity-inducing component that guides NK cells in an antibody-dependent cytotoxic (ADCC) reaction to attack the marrow graft. On the basis of this hypothesis, one would postulate that nonresponder marrow graft recipients can be converted into responders by injection with antibody of appropriate specificity. Results presented in this report show that this is indeed possible. Specific monoclonal or polyclonal antibody of IgG isotype induces marrow graft rejection in nonresponder recipients. This can be demonstrated in allogeneic as well as in semi-allogeneic (hybrid resistance) donor-recipient strain combinations. Antibody-induced marrow graft rejection is independent of complement and dependent on the presence of NK cells. Surprisingly, graft rejection induced by antibody is quite efficient in allogeneic and semiallogeneic marrow donor-recipient combinations, whereas it is generally poor in syngeneic combinations. This result is not understood if NK cells lyse bone marrow cells solely in an ADCC-type reaction. Because NK cells can lyse targets in an antibody-dependent as well as independent reaction, it is proposed that the binding of NK cells to targets via their receptors plays an additional role in the rejection of bone marrow in vivo. Preliminary evidence for this possibility is that NK cells in the apparent absence of antibody may have a detectable suppressive effect on the growth of marrow grafts in F1 hybrid mice transplanted with parental marrow grafts.

Cytotoxic granules from killer cells: specificity of granules and insertion of channels of defined size into target membranes.

The channel-forming polyperforins P1 and P2 are thought to be formed from the contents of dense core vesicles of cytolytic effector cells. To test this hypothesis, granules from various cytotoxic effector cells were assayed for cytolytic activity on nucleated or unnucleated targets. The results show that in general, granules from cytolytic effector cells are cytolytic, whereas granules from noncytotoxic cells are not. Cytotoxicity of granules is not specific, but there appears to be a preference in that nucleated targets are lysed better than are erythrocytes by granules from T killer or natural killer cells. Granules from CTLL-2, however, preferentially lyse erythrocyte targets. This cell line has been in culture for a long period of time and has lost its cytotoxicity. We tested whether granules from CTLL-2 caused formation of transmembrane pores in erythrocyte target membranes. We found that granule- and complement-induced lesions have similar pore sizes. They are big enough to allow the total release of alpha-bungarotoxin, an 8000 Mr polypeptide with dimensions of 4 X 2.5 nm. Larger molecules are released partially or not at all. Under acidic conditions (pH 5.4) granules do not permeabilize target membranes. This may suggest a pH-dependent control mechanism in the formation, insertion, or function of polyperforin channels, in addition to a previously recognized Ca2+-dependent mechanism. Permeabilization of lipid vesicles by granules was studied to explore what the molecular requirements for channel insertion into membranes may be. Release of alpha-bungarotoxin induced by granules was observed in liposomes made of soybean lipid with or without cholesterol, suggesting that no membrane component other than lipid is required for the insertion of polyperforins, and that the action of polyperforins does not require other mechanisms in the target cell. When pure lecithin from soybean and egg, or synthetic phosphatidylcholines were used, slower release or no release of macromolecules was observed. We suggest that some kind of lipid specificity is required for perforin action. This may be related to the hydrophobic region of the lipid bilayer rather than to the polar portion, because different lecithins with varying fatty acid composition gave similar results.

T killer cells play a role in allogeneic bone marrow graft rejection but not in hybrid resistance.

Results of recent experiments have provided compelling evidence supporting the hypothesis that the acute rejection of bone marrow transplants by allogeneic and semiallogeneic recipients is principally due to the action of natural killer (NK) cells. The observed specificity of graft rejection is likely induced by target-specific antibody that guides the NK cells in an antibody-dependent cytolytic reaction resulting in the elimination of the graft. The sole involvement of NK cells in marrow graft rejection, however, is contradicted by several observations that point to the environment of specific T cells. Results presented in this paper demonstrate that in allogeneic marrow graft rejection models, T killer cells are capable of causing graft rejection provided a prior sensitization phase is allowed. Thus, mice not able to reject marrow grafts in a primary response via their NK cells will do so in a primed secondary response via their T cells. Rejection is specific in that only marrow grafts H-2 identical to the sensitizing marrow graft are rejected. Sensitization for NK cell independent marrow graft rejection can be accomplished by prior priming with allogeneic tumor cells or by injection of cloned T killer cells. In contrast to bone marrow allograft rejection, the hybrid resistance model in which F1 hybrid mice reject parental marrow grafts does not appear to induce T killer cells in vivo. Neither marrow grafts nor tumor cells prime F1 hybrids for a second-set parental graft rejection. Moreover, F1 hybrid antiparental T killer cells induced in vitro and adoptively transferred in vivo fail to transfer hybrid resistance. Therefore, there appear to be potent mechanisms acting in vivo that suppress the action or induction of F1 hybrid T killer cells specific to parental antigens.

Megaloblastic anaemia after pelvic radiotherapy for carcinoma of the cervix.

A 71-year-old woman was treated with radiotherapy for carcinoma of the cervix. Nine year later she was found at laparotomy to have a thickened narrow ileum. At the time she had an iron-deficiency anaemia and when this was treated the blood picture changed to that of a severe megaloblastic anaemia. This was due to cobalamin deficiency resulting from malabsorption of cobalamin by the damaged ileum.