Conditionally immortalized neural progenitor cells grafted to the striatum exhibit site-specific neuronal differentiation and establish connections with the host globus pallidus

The cell line RN33B has been reported to differentiate into neurons in a site-specific manner when grafted to the cortex and hippocampus of adult rats. To investigate the fate of RN33B cells in a subcortical structure, we grafted RN33B cells into the intact or excitoxically lesioned striatum of adult or neonatal rats. The total number and phenotypic characteristics of the [3H]thymidine-labeled grafted cells were analyzed at different time points after transplantation. Transplanted RN33B cells were found to survive, integrate, and differentiate into both neurons and astrocytes, and a significant proportion of the cells (approx. 10%) were found to differentiate into cells with morphological and phenotypic characteristics of medium-sized striatal projection neurons. Retrograde tracing showed that at least some of the graft-derived neurons were capable of establishing connections with one of the primary striatal targets, the globus pallidus. These findings demonstrate a remarkable capacity of the RN33B cells for site-specific neuronal differentiation in both the adult and the developing striatum and suggest that the same differentiating factors that are operating during normal neurogenesis in brain development are retained, at least to some extent, also in the adult CNS.     

Synthesis, antimalarial activity, and molecular modeling of tebuquine analogues

Tebuquine (5) is a 4-aminoquinoline that is significantly more active than amodiaquine (2) and chloroquine (1) both in vitro and in vivo. We have developed a novel more efficient synthetic route to tebuquine analogues which involves the use of a palladium-catalyzed Suzuki reaction to introduce the 4-chlorophenyl moiety into the 4-hydroxyaniline side chain. Using similar methodology, novel synthetic routes to fluorinated (7a, b) and a dehydroxylated (7c) analogue of tebuquine have also been developed. The novel analogues were subjected to testing against the chloroquine sensitive HB3 strain and the chloroquine resistant K1 strain of Plasmodium falciparum. Tebuquine was the most active compound tested against both strains of Plasmodia. Replacement of the 4-hydroxy function with either fluorine or hydrogen led to a decrease in antimalarial activity. Molecular modeling of the tebuquine analogues alongside amodiaquine and chloroquine reveals that the inter-nitrogen separation in this class of drugs ranges between 9.36 and 9.86 A in their isolated diprotonated form and between 7.52 and 10.21 A in the heme-drug complex. Further modeling studies on the interaction of 4-aminoquinolines with the proposed cellular receptor heme revealed favorable interaction energies for chloroquine, amodiaquine, and tebuquine analogues. Tebuquine, the most potent antimalarial in the series, had the most favorable interaction energy calculated in both the in vacuo and solvent-based simulation studies. Although fluorotebuquine (7a) had a similar interaction energy to tebuquine, this compound had significantly reduced potency when compared with (5). This disparity is possibly the result of the reduced cellular accumulation (CAR) of fluorotebuquine when compared with tebuquine within the parasite. Measurement of the cellular accumulation of the tebuquine analogues and seven related 4-aminoquinolines shows a significant relationship (r = 0.98) between the CAR of 4-aminoquinoline drugs and the reciprocal of drugs IC50.     

Weight loss education: the challenge of a new paradigm

The functional effects of adenosine 5'-triphosphate (ATP), uridine 5'-triphosphate (UTP), adenosine 5'-tetraphosphate (AP4) and the diadenosine polyphosphates P1,P3-diadenosine triphosphate (Ap3A), P1,P4-diadenosine tetraphosphate (Ap4A) and P1,P5-diadenosine pentaphosphate (Ap5A) were studied in two isolated smooth muscle preparations thought to contain P2Y (P2Y1) receptors, the guinea-pig taenia caeci (which relaxes to ATP) and the rat colon muscularis mucosae (which contracts to ATP). In addition, the breakdown of these compounds by the rat colon muscularis mucosae was investigated by high pressure liquid chromatography. In the guinea-pig taenia caeci all the purine nucleotides caused relaxation with a potency order of Ap3A=Ap4A> ATP>AP4=Ap5A, and these relaxations were antagonised by suramin with apparent pA2 values in the region of 5, consistent with activation of a P2Y1 receptor. In the rat colon muscularis mucosae the nucleotides caused contraction with a potency order of Ap3A = Ap4A>ATP=AP4 =Ap5A >UTP. However, while suramin (100 microM) inhibited responses to ATP and UTP at all concentrations of agonist, it only inhibited contractions induced by the higher concentrations of AP4, Ap3A and Ap4A and had little effect on contractions induced by Ap5A. A higher concentration of suramin (1 mM) enhanced contractions induced by ATP but greatly inhibited those induced by UTP and had no effect on responses to the other agonists. The A1 adenosine receptor antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX; 10 nM) had no effect on responses to ATP or UTP but inhibited responses to Ap3A, Ap4A, Ap5A and AP4. A combination of suramin (1 mM) and DPCPX (10 nM) almost abolished responses to all the agonists. ATP and UTP were rapidly degraded by the rat colon muscularis mucosae while AP4, Ap3A, Ap4A and Ap5A were degraded more slowly, and the major product detected after breakdown of the purine nucleotides was inosine rather than adenosine. The breakdown of all the nucleotides was inhibited by suramin (1 mM), although this inhibition did not achieve statistical significance in the case of ATP. These results show that while the diadenosine polyphosphates appear to act as P2 agonists in the taenia caeci, in the rat colon muscularis mucosae their major action is via adenosine A1 receptors rather than via P2 receptors. In addition, although they are more stable than ATP or UTP, their action in this tissue is clearly affected by their degradation which complicates the effects of suramin.     

Oxidation and antioxidation of human low-density lipoprotein and plasma exposed to 3-morpholinosydnonimine and reagent peroxynitrite

As peroxynitrite is implicated as an oxidant for low-density lipoprotein (LDL) in atherogenesis, we investigated this process using reagent peroxynitrite (ONOO-) and 3-morpholinosydnonimine (SIN-1, which produces peroxynitrite via generation of NO. and O2.-). LDL oxidation was assessed by the consumption of ubiquinol-10 (CoQ10H2) and alpha-tocopherol (alpha-TOH), the accumulation of cholesteryl ester hydro(pero)xides, the loss of lysine (Lys) and tryptophan (Trp) residues, and the change in relative electrophoretic mobility. Exposure to ONOO- or SIN-1 resulted in rapid (<1 min) and time-dependent oxidation, respectively, of LDL's lipids and protein. Manipulating the alpha-TOH content by in vivo or in vitro means showed that when ONOO- or SIN-1 was used at oxidant-to-LDL ratios of <100:1 the extent of LDL lipid peroxidation increased with increasing initial alpha-TOH content. In contrast, in vivo enrichment with the co-antioxidant CoQ10H2 decreased LDL lipid peroxidation induced by SIN-1. At oxidant-to-LDL ratios of >200:1, alpha-TOH enrichment decreased LDL lipid peroxidation for both SIN-1 and ONOO-. In contrast to lipid peroxidation, altering the alpha-TOH content of LDL did not affect Trp or Lys loss, independent of the amounts of either oxidant added. Aqueous antioxidants inhibited ONOO--induced lipid and protein oxidation with the order of efficacy: 3-hydroxyanthranilate (3-HAA) > urate > ascorbate. With SIN-1, these antioxidants inhibited Trp consumption, while only the co-antioxidants ascorbate and 3-HAA prevented alpha-TOH consumption and lipid peroxidation. Exposure of human plasma to SIN-1 resulted in the loss of ascorbate followed by loss of CoQ10H2 and bilirubin. Lipid peroxidation was inhibited during this period, though proceeded as a radical-chain process after depletion of these antioxidants and in the presence of alpha-TOH and urate. Bicarbonate at physiological concentrations decreased ONOO--induced lipid and protein oxidation, whereas it enhanced SIN-1-induced lipid peroxidation, Trp consumption, and alpha-tocopheroxyl radical formation in LDL. These results indicate an important role for tocopherol-mediated peroxidation and co-antioxidation in peroxynitrite-induced lipoprotein lipid peroxidation, especially when peroxynitrite is formed time-dependently by SIN-1. The studies also highlight differences between ONOO-- and SIN-1-induced LDL oxidation with regards to the effects of bicarbonate, ascorbate, and urate.     

Encoding features of complex and unfamiliar objects

This study explored the acquisition of features from complex, unfamiliar objects. It tested the principle of top-down encoding, which predicts that the time needed to detect a difference between stimuli that differ in only one critical feature increases and recognition decreases as the level of that feature decreases. Results of Experiment 1 supported these hypotheses. Experiment 2 eliminated retroactive interference as an explanation for the results of Experiment 1. Experiment 3 showed that top-down encoding can be altered by explicit instructions to attend the relevant feature. It also showed that discriminability due to size was not a factor in Experiments 1-3. Experiment 4 showed that the top-down principle can account for how people encode features as a function of task demands. Overall, the results indicate that under normal attention conditions, the probability of encoding a feature decreases with its structural level. However, this tendency can be altered by explicit instructions or other factors.     

Numerical simulations of void linkage in model materials using a nonlocal ductile damage approximation

Experiments on the growth and linkage of 10 μm diameter holes laser drilled in high precision patterns into Al-plates were modelled with finite elements. The simulations used geometries identical to those of the experiments and incorporated ductile damage by element removal under the control of a ductile damage indicator based on the micromechanical studies of Rice and Tracey. A regularization of the problem was achieved through an integral-type nonlocal model based on the smoothing of the rate of a damage indicator D over a characteristic length L. The simulation does not predict the experimentally observed damage acceleration either in the case where no damage is included or when only a local damage model is used. However, the full three-dimensional simulations based on the nonlocal damage methodology do predict both the failure path and the failure strain at void linkage for almost all configurations studied. For the cases considered the critical parameter controlling the local deformations at void linkage was found to be the ratio between hole diameter and hole spacing.     

The pericentromeric inversion, inv (6)(p25q13), is a novel diagnostic marker in chondromyxoid fibroma

Chondromyxoid fibroma is a benign bone tumor that arises most commonly in the metaphysis of long bones in young adults. The cytogenetic features of this tumor are not well known. In this study, four chondromyxoid fibromas were karyotyped after short-term cell culture. All of the tumors contained clonal rearrangements of chromosome 6, and each of these rearrangements involved band 6q13. Two tumors contained a pericentromeric inversion, inv (6)(p25q13), which was described recently in chondromyxoid fibroma. 6q13 rearrangements are not associated with other types of bone and soft tissue tumors, and the inv (6)(p25q13) is reported only in chondromyxoid fibroma. Hence, this cytogenetic marker might be helpful in distinguishing chondromyxoid fibroma from chondrosarcoma and other histologic mimics. The consistent occurrence of 6q13 rearrangements suggests a specific oncogenic mechanism in chondromyxoid fibroma, most likely involving oncogene activation.     

A chromosomally based tod-luxCDABE whole-cell reporter for benzene, toluene, ethybenzene, and xylene (BTEX) sensing

A tod-luxCDABE fusion was constructed and introduced into the chromosome of Pseudomonas putida F1, yielding the strain TVA8. This strain was used to examine the induction of the tod operon when exposed to benzene, toluene, ethylbenzene, and xylene (BTEX) compounds and aqueous solutions of JP-4 jet fuel constituents. Since this system contained the complete lux cassette (luxCDABE), bacterial bioluminescence in response to putative chemical inducers of the tod operon was measured on-line in whole cells without added aldehyde substrate. There was an increasing response to toluene concentrations from 30 micrograms/liter to 50 mg/liter, which began to saturate at higher concentrations. The detection limit was 30 micrograms/liter. There was a significant light response to benzene, m- and p-xylenes, phenol, and water-soluble JP-4 jet fuel components, but there was no bioluminescence response upon exposure to o-xylene. The transposon insertion was stable and had no negative effect on cell growth.