Boron nitride substrates for high-quality graphene electronics

Graphene devices on standard SiO(2) substrates are highly disordered, exhibiting characteristics that are far inferior to the expected intrinsic properties of graphene. Although suspending the graphene above the substrate leads to a substantial improvement in device quality, this geometry imposes severe limitations on device architecture and functionality. There is a growing need, therefore, to identify dielectrics that allow a substrate-supported geometry while retaining the quality achieved with a suspended sample. Hexagonal boron nitride (h-BN) is an appealing substrate, because it has an atomically smooth surface that is relatively free of dangling bonds and charge traps. It also has a lattice constant similar to that of graphite, and has large optical phonon modes and a large electrical bandgap. Here we report the fabrication and characterization of high-quality exfoliated mono- and bilayer graphene devices on single-crystal h-BN substrates, by using a mechanical transfer process. Graphene devices on h-BN substrates have mobilities and carrier inhomogeneities that are almost an order of magnitude better than devices on SiO(2). These devices also show reduced roughness, intrinsic doping and chemical reactivity. The ability to assemble crystalline layered materials in a controlled way permits the fabrication of graphene devices on other promising dielectrics and allows for the realization of more complex graphene heterostructures.

MCML--Monte Carlo modeling of light transport in multi-layered tissues

A Monte Carlo model of steady-state light transport in multi-layered tissues (MCML) has been coded in ANSI Standard C; therefore, the program can be used on various computers. Dynamic data allocation is used for MCML, hence the number of tissue layers and grid elements of the grid system can be varied by users at run time. The coordinates of the simulated data for each grid element in the radial and angular directions are optimized. Some of the MCML computational results have been verified with those of other theories or other investigators. The program, including the source code, has been in the public domain since 1992.

Therapeutic benefit of intravenous administration of bone marrow stromal cells after cerebral ischemia in rats

BACKGROUND AND PURPOSE

We tested the hypothesis that intravenous infusion of bone marrow derived-marrow stromal cells (MSCs) enter the brain and reduce neurological functional deficits after stroke in rats.

METHODS

Rats (n=32) were subjected to 2 hours of middle cerebral artery occlusion (MCAO). Test groups consisted of MCAO alone (group 1, n=6); intravenous infusion of 1x10(6) MSCs at 24 hours after MCAO (group 2, n=6); or infusion of 3x10(6) MSCs (group 3, n=7). Rats in groups 1 to 3 were euthanized at 14 days after MCAO. Group 4 consisted of MCAO alone (n=6) and group 5, intravenous infusion of 3x10(6) MSCs at 7 days after MCAO (n=7). Rats in groups 4 and 5 were euthanized at 35 days after MCAO. For cellular identification, MSCs were prelabeled with bromodeoxyuridine. Behavioral tests (rotarod, adhesive-removal, and modified Neurological Severity Score [NSS]) were performed before and at 1, 7, 14, 21, 28, and 35 days after MCAO. Immunohistochemistry was used to identify MSCs or cells derived from MSCs in brain and other organs. RESULTS Significant recovery of somatosensory behavior and Neurological Severity Score (P<0.05) were found in animals infused with 3x10(6) MSCs at 1 day or 7 days compared with control animals. MSCs survive and are localized to the ipsilateral ischemic hemisphere, and a few cells express protein marker phenotypic neural cells.

CONCLUSIONS

MSCs delivered to ischemic brain tissue through an intravenous route provide therapeutic benefit after stroke. MSCs may provide a powerful autoplastic therapy for stroke.

Tumor necrosis factor receptor family member RANK mediates osteoclast differentiation and activation induced by osteoprotegerin ligand

A receptor that mediates osteoprotegerin ligand (OPGL)-induced osteoclast differentiation and activation has been identified via genomic analysis of a primary osteoclast precursor cell cDNA library and is identical to the tumor necrosis factor receptor (TNFR) family member RANK. The RANK mRNA was highly expressed by isolated bone marrow-derived osteoclast progenitors and by mature osteoclasts in vivo. Recombinant OPGL binds specifically to RANK expressed by transfected cell lines and purified osteoclast progenitors. Transgenic mice expressing a soluble RANK-Fc fusion protein have severe osteopetrosis because of a reduction in osteoclasts, similar to OPG transgenic mice. Recombinant RANK-Fc binds with high affinity to OPGL in vitro and blocks osteoclast differentiation and activation in vitro and in vivo. Furthermore, polyclonal Ab against the RANK extracellular domain promotes osteoclastogenesis in bone marrow cultures suggesting that RANK activation mediates the effects of OPGL on the osteoclast pathway. These data indicate that OPGL-induced osteoclastogenesis is directly mediated through RANK on osteoclast precursor cells.

Leptin-regulated endocannabinoids are involved in maintaining food intake

Leptin is the primary signal through which the hypothalamus senses nutritional state and modulates food intake and energy balance. Leptin reduces food intake by upregulating anorexigenic (appetite-reducing) neuropeptides, such as alpha-melanocyte-stimulating hormone, and downregulating orexigenic (appetite-stimulating) factors, primarily neuropeptide Y. Genetic defects in anorexigenic signalling, such as mutations in the melanocortin-4 (ref. 5) or leptin receptors, cause obesity. However, alternative orexigenic pathways maintain food intake in mice deficient in neuropeptide Y. CB1 cannabinoid receptors and the endocannabinoids anandamide and 2-arachidonoyl glycerol are present in the hypothalamus, and marijuana and anandamide stimulate food intake. Here we show that following temporary food restriction, CB1 receptor knockout mice eat less than their wild-type littermates, and the CB1 antagonist SR141716A reduces food intake in wild-type but not knockout mice. Furthermore, defective leptin signalling is associated with elevated hypothalamic, but not cerebellar, levels of endocannabinoids in obese db/db and ob/ob mice and Zucker rats. Acute leptin treatment of normal rats and ob/ob mice reduces anandamide and 2-arachidonoyl glycerol in the hypothalamus. These findings indicate that endocannabinoids in the hypothalamus may tonically activate CB1 receptors to maintain food intake and form part of the neural circuitry regulated by leptin.

Expanding the genetic code of Escherichia coli

A unique transfer RNA (tRNA)/aminoacyl-tRNA synthetase pair has been generated that expands the number of genetically encoded amino acids in Escherichia coli. When introduced into E. coli, this pair leads to the in vivo incorporation of the synthetic amino acid O-methyl-l-tyrosine into protein in response to an amber nonsense codon. The fidelity of translation is greater than 99%, as determined by analysis of dihydrofolate reductase containing the unnatural amino acid. This approach should provide a general method for increasing the genetic repertoire of living cells to include a variety of amino acids with novel structural, chemical, and physical properties not found in the common 20 amino acids.

Control of memory formation through regulated expression of a CaMKII transgene

One of the major limitations in the use of genetically modified mice for studying cognitive functions is the lack of regional and temporal control of gene function. To overcome these limitations, a forebrain-specific promoter was combined with the tetracycline transactivator system to achieve both regional and temporal control of transgene expression. Expression of an activated calcium-independent form of calcium-calmodulin-dependent kinase II (CaMKII) resulted in a loss of hippocampal long-term potentiation in response to 10-hertz stimulation and a deficit in spatial memory, a form of explicit memory. Suppression of transgene expression reversed both the physiological and the memory deficit. When the transgene was expressed at high levels in the lateral amygdala and the striatum but not other forebrain structures, there was a deficit in fear conditioning, an implicit memory task, that also was reversible. Thus, the CaMKII signaling pathway is critical for both explicit and implicit memory storage, in a manner that is independent of its potential role in development.

New Ballard Score, expanded to include extremely premature infants

The Ballard Maturational Score was refined and expanded to achieve greater accuracy and to include extremely premature neonates. To test validity, accuracy, interrater reliability, and optimal postnatal age at examination, the resulting New Ballard Score (NBS) was assessed for 578 newly born infants and the results were analyzed. Gestational ages ranged from 20 to 44 weeks and postnatal ages at examination ranged from birth to 96 hours. In 530 infants, gestational age by last menstrual period was confirmed by agreement within 2 weeks with gestational age by prenatal ultrasonography (C-GLMP). For these infants, correlation between gestational age by NBS and C-GLMP was 0.97. Mean differences between gestational age by NBS and C-GLMP were 0.32 +/- 1.58 weeks and 0.15 +/- 1.46 weeks among the extremely premature infants (less than 26 weeks) and among the total population, respectively. Correlations between the individual criteria and C-GLMP ranged from 0.72 to 0.82. Interrater reliability of NBS, as determined by correlation between raters who rated the same subgroup of infants, ws 0.95. For infants less than 26 weeks of gestational age, the greatest validity (97% within 2 weeks of C-GLMP) was seen when the examination was performed before 12 hours of postnatal age. For infants at least 26 weeks of gestational age, percentages of agreement with C-GLMP remained constant, averaging 92% for all postnatal age categories up to 96 hours. The NBS is a valid and accurate gestational assessment tool for extremely premature infants and remains valid for the entire newborn infant population.

Intravenous administration of human umbilical cord blood reduces behavioral deficits after stroke in rats

BACKGROUND AND PURPOSE

Human umbilical cord blood cells (HUCBC) are rich in stem and progenitor cells. In this study we tested whether intravenously infused HUCBC enter brain, survive, differentiate, and improve neurological functional recovery after stroke in rats. In addition, we tested whether ischemic brain tissue extract selectively induces chemotaxis of HUCBC in vitro.

METHODS

Adult male Wistar rats were subjected to transient (2-hour) middle cerebral artery occlusion (MCAO). Experimental groups were as follows: group 1, MCAO alone (n=5); group 2, 3x10(6) HUCBC injected into tail vein at 24 hours after MCAO (n=6) (animals of groups 1 and 2 were killed at 14 days after MCAO); group 3, MCAO alone (n=5); group 4, MCAO injected with PBS at 1 day after stroke (n=8); and group 5, 3x10(6) HUCBC injected into tail vein at 7 days after MCAO (n=5). Rats of groups 3, 4, and 5 were killed at 35 days after MCAO. Behavioral tests (rotarod and Modified Neurological Severity Score [mNSS]) were performed. Immunohistochemical staining was used to identify cells derived from HUCBC. Chemotactic activity of ischemia brain tissue extracts toward HUCBC at different time points was evaluated in vitro.

RESULTS

Treatment at 24 hours after MCAO with HUCBC significantly improved functional recovery, as evidenced by the rotarod test and mNSS (P<0.05). Treatment at 7 days after MCAO with HUCBC significantly improved function only on the mNSS (P<0.05). Some HUCBC were reactive for the astrocyte marker glial fibrillary acidic protein and the neuronal markers NeuN and microtubule-associated protein 2. In vitro, significant HUCBC migration activity was present at 24 hours after MCAO (P<0.01) compared with normal brain tissue.

CONCLUSIONS

Intravenously administered HUCBC enter brain, survive, migrate, and improve functional recovery after stroke. HUCBC transplantation may provide a cell source to treat stroke.

Mutations in T-cell antigen receptor genes alpha and beta block thymocyte development at different stages

Analysis of mice carrying mutant T-cell antigen receptor (TCR) genes indicates that TCR-beta gene rearrangement or expression is critical for the differentiation of CD4-CD8- thymocytes to CD4+CD8+ thymocytes, as well as for the expansion of the pool of CD4+CD8+ cells. TCR-alpha is irrelevant in these developmental processes. The development of gamma delta T cells does not depend on either TCR-alpha or TCR-beta.

Peptoids: a modular approach to drug discovery

Peptoids, oligomers of N-substituted glycines, are described as a motif for the generation of chemically diverse libraries of novel molecules. Ramachandran-type plots were calculated and indicate a greater diversity of conformational states available for peptoids than for peptides. The monomers incorporate t-butyl-based side-chain and 9-fluorenylmethoxy-carbonyl alpha-amine protection. The controlled oligomerization of the peptoid monomers was performed manually and robotically with in situ activation by either benzotriazol-1-yloxytris(pyrrolidino)phosphonium hexafluorophosphate or bromotris(pyrrolidino)phosphonium hexaflurophosphate. Other steps were identical to peptide synthesis using alpha-(9-fluorenylmethoxycarbonyl)amino acids. A total of 15 monomers and 10 oligomers (peptoids) are described. Preliminary data are presented on the stability of a representative oligopeptoid to enzymatic hydrolysis. Peptoid versions of peptide ligands of three biological systems (bovine pancreatic alpha-amylase, hepatitis A virus 3C proteinase, and human immunodeficiency virus transactivator-responsive element RNA) were found with affinities comparable to those of the corresponding peptides. The potential use of libraries of these compounds in receptor- or enzyme-based assays is discussed.

Human marrow stromal cell therapy for stroke in rat: neurotrophins and functional recovery

OBJECTIVE

To test the effect of i.v.-injected human bone marrow stromal cells (hMSC) on neurologic functional deficits after stroke in rats.

METHODS

Rats were subjected to transient middle cerebral artery occlusion and IV injected with 3 x 10(6) hMSC 1 day after stroke. Functional outcome was measured before and 1, 7, and 14 days after stroke. Mixed lymphocyte reaction and the development of cytotoxic T lymphocytes measured the immune rejection of hMSC. A monoclonal antibody specific to human cellular nuclei (mAb1281) was used to identify hMSC and to measure neural phenotype. ELISA analyzed neurotrophin levels in cerebral tissue from hMSC-treated or nontreated rats. Bromodeoxyuridine injections were used to identify newly formed cells.

RESULTS

Significant recovery of function was found in rats treated with hMSC at 14 days compared with control rats with ischemia. Few (1 to 5%) hMSC expressed proteins phenotypic of brain parenchymal cells. Brain-derived neurotrophic factor and nerve growth factor significantly increased, and apoptotic cells significantly decreased in the ischemic boundary zone; significantly more bromodeoxyuridine-reactive cells were detected in the subventricular zone of the ischemic hemisphere of rats treated with hMSC. hMSC induced proliferation of lymphocytes without the induction of cytotoxic T lymphocytes.

CONCLUSION

Neurologic benefit resulting from hMSC treatment of stroke in rats may derive from the increase of growth factors in the ischemic tissue, the reduction of apoptosis in the penumbral zone of the lesion, and the proliferation of endogenous cells in the subventricular zone.

Subcortical brain volume abnormalities in 2028 individuals with schizophrenia and 2540 healthy controls via the ENIGMA consortium

The profile of brain structural abnormalities in schizophrenia is still not fully understood, despite decades of research using brain scans. To validate a prospective meta-analysis approach to analyzing multicenter neuroimaging data, we analyzed brain MRI scans from 2028 schizophrenia patients and 2540 healthy controls, assessed with standardized methods at 15 centers worldwide. We identified subcortical brain volumes that differentiated patients from controls, and ranked them according to their effect sizes. Compared with healthy controls, patients with schizophrenia had smaller hippocampus (Cohen's d=-0.46), amygdala (d=-0.31), thalamus (d=-0.31), accumbens (d=-0.25) and intracranial volumes (d=-0.12), as well as larger pallidum (d=0.21) and lateral ventricle volumes (d=0.37). Putamen and pallidum volume augmentations were positively associated with duration of illness and hippocampal deficits scaled with the proportion of unmedicated patients. Worldwide cooperative analyses of brain imaging data support a profile of subcortical abnormalities in schizophrenia, which is consistent with that based on traditional meta-analytic approaches. This first ENIGMA Schizophrenia Working Group study validates that collaborative data analyses can readily be used across brain phenotypes and disorders and encourages analysis and data sharing efforts to further our understanding of severe mental illness.

Ich-1, an Ice/ced-3-related gene, encodes both positive and negative regulators of programmed cell death

We report here the isolation and characterization of Ich-1, a gene related to the C. elegans cell death gene ced-3 and the mammalian homolog of ced-3, interleukin-1 beta-converting enzyme (ICE). Alternative splicing results in two distinct Ich-1 mRNA species. One mRNA species encodes a protein product of 435 amino acids (ICH-1L) that is homologous to both the P20 and P10 subunits of ICE (27% identity) and the entire CED-3 protein (28% identity). The other mRNA encodes a 312 amino acid truncated version of ICH-1L protein (ICH-1S). Overexpression of IchL induces programmed cell death, suggesting that Ich-1 is also a mammalian programmed cell death gene. More interestingly, overexpression of the Ich-1S suppresses Rat-1 cell death induced by serum deprivation. These observations suggest that Ich-1 plays an important role in both positive and negative regulation of programmed cell death in vertebrate animals.

The diversity of the DnaJ/Hsp40 family, the crucial partners for Hsp70 chaperones

DnaJ/Hsp40 (heat shock protein 40) proteins have been preserved throughout evolution and are important for protein translation, folding, unfolding, translocation, and degradation, primarily by stimulating the ATPase activity of chaperone proteins, Hsp70s. Because the ATP hydrolysis is essential for the activity of Hsp70s, DnaJ/Hsp40 proteins actually determine the activity of Hsp70s by stabilizing their interaction with substrate proteins. DnaJ/Hsp40 proteins all contain the J domain through which they bind to Hsp70s and can be categorized into three groups, depending on the presence of other domains. Six DnaJ homologs have been identified in Escherichia coli and 22 in Saccharomyces cerevisiae. Genome-wide analysis has revealed 41 DnaJ/Hsp40 family members (or putative members) in humans. While 34 contain the typical J domains, 7 bear partially conserved J-like domains, but are still suggested to function as DnaJ/ Hsp40 proteins. DnaJA2b, DnaJB1b, DnaJC2, DnaJC20, and DnaJC21 are named for the first time in this review; all other human DnaJ proteins were dubbed according to their gene names, e.g. DnaJA1 is the human protein named after its gene DNAJA1. This review highlights the progress in studying the domains in DnaJ/Hsp40 proteins, introduces the mechanisms by which they interact with Hsp70s, and stresses their functional diversity.

Hofstadter's butterfly and the fractal quantum Hall effect in moiré superlattices

Electrons moving through a spatially periodic lattice potential develop a quantized energy spectrum consisting of discrete Bloch bands. In two dimensions, electrons moving through a magnetic field also develop a quantized energy spectrum, consisting of highly degenerate Landau energy levels. When subject to both a magnetic field and a periodic electrostatic potential, two-dimensional systems of electrons exhibit a self-similar recursive energy spectrum. Known as Hofstadter's butterfly, this complex spectrum results from an interplay between the characteristic lengths associated with the two quantizing fields, and is one of the first quantum fractals discovered in physics. In the decades since its prediction, experimental attempts to study this effect have been limited by difficulties in reconciling the two length scales. Typical atomic lattices (with periodicities of less than one nanometre) require unfeasibly large magnetic fields to reach the commensurability condition, and in artificially engineered structures (with periodicities greater than about 100 nanometres) the corresponding fields are too small to overcome disorder completely. Here we demonstrate that moiré superlattices arising in bilayer graphene coupled to hexagonal boron nitride provide a periodic modulation with ideal length scales of the order of ten nanometres, enabling unprecedented experimental access to the fractal spectrum. We confirm that quantum Hall features associated with the fractal gaps are described by two integer topological quantum numbers, and report evidence of their recursive structure. Observation of a Hofstadter spectrum in bilayer graphene means that it is possible to investigate emergent behaviour within a fractal energy landscape in a system with tunable internal degrees of freedom.

In vitro activation of CPP32 and Mch3 by Mch4, a novel human apoptotic cysteine protease containing two FADD-like domains

Emerging evidence suggests that an amplifiable protease cascade consisting of multiple aspartate specific cysteine proteases (ASCPs) is responsible for the apoptotic changes observed in mammalian cells undergoing programmed cell death. Here we describe the cloning of two novel ASCPs from human Jurkat T-lymphocytes. Like other ASCPs, the new proteases, named Mch4 and Mch5, are derived from single chain proenzymes. However, their putative active sites contain a QACQG pentapeptide instead of the QACRG present in ail known ASCPs. Also, their N termini contain FADD-like death effector domains, suggesting possible interaction with FADD. Expression of Mch4 in Escherichia coli produced an active protease that, like other ASCPs, was potently inhibited (Kj = 14 nM) by the tetrapeptide aldehyde DEVD-CHO. Interestingly, both Mch4 and the serine protease granzyme B cleave recombinant proCPP32 and proMch3 at a conserved IXXD-S sequence to produce the large and small subunits of the active proteases. Granzyme B also cleaves proMch4 at a homologous IXXD-A processing sequence to produce mature Mch4. These observations suggest that CPP32 and Mch3 are targets of mature Mch4 protease in apoptotic cells. The presence of the FADD-like domains in Mch4 and Mch5 suggests a role for these proteases in the Fas-apoptotic pathway. In addition, these proteases could participate in the granzyme B apoptotic pathways.

The TAF(II)250 subunit of TFIID has histone acetyltransferase activity

The transcription initiation factor TFIID is a multimeric protein complex composed of TATA box-binding protein (TBP) and many TBP-associated factors (TAF(II)s). TAF(II)s are important cofactors that mediate activated transcription by providing interaction sites for distinct activators. Here, we present evidence that human TAF(II)250 and its homologs in Drosophila and yeast have histone acetyltransferase (HAT) activity in vitro. HAT activity maps to the central, most conserved portion of dTAF(II)230 and yTAF(II)130. The HAT activity of dTAF(II)230 resembles that of yeast and human GCN5 in that it is specific for histones H3 and H4 in vitro. Our findings suggest that targeted histone acetylation at specific promoters by TAF(II)250 may be involved in mechanisms by which TFIID gains access to transcriptionally repressed chromatin.

Plasma glucose levels and diabetes are independent predictors for mortality and morbidity in patients with SARS

AIMS

To investigate the relationships between a known history of diabetes and ambient fasting plasma glucose (FPG) levels with death and morbidity rates in patients with severe acute respiratory syndrome (SARS).

METHODS

In this retrospective analysis, the clinical and biochemical characteristics of 135 patients who had died from SARS, 385 survivors of SARS and 19 patients with non-SARS pneumonia were compared.

RESULTS

All patients were treated according to a predefined protocol. Before steroid treatment, the mean FPG level was significantly higher in the SARS group (deceased vs. survivors vs. non-SARS pneumonia group: 9.7 +/- 5.2 vs. 6.5 +/- 3.0 vs. 5.1 +/- 1.0 mmol/l, P < 0.01). In the SARS group, the percentage of patients with a known history of diabetes was significantly higher in the deceased patients than in the survivors (21.5% vs. 3.9%, P < 0.01). Among patients with no known history of diabetes and before commencement of steroid therapy, those who had hypoxaemia (SaO(2) < 93%) had higher FPG levels than those who did not have hypoxia in both the survivor (8.7 +/- 4.9 vs. 6.3 +/- 2.1 mmol/l, P < 0.001) and deceased (9.8 +/- 4.8 vs. 7.2 +/- 1.5 mmol/l, P < 0.001) groups. A known history of diabetes [odds ratio (OR) 3.0, 95% confidence interval (CI) 1.4, 6.3; P = 0.005] and FPG > or = 7.0 mmol/l before steroid treatment (OR 3.3, 95% CI 1.4, 7.7, P = 0.006) were independent predictors of death. During the course of the illness, FPG levels were negatively associated with SaO(2) (beta =-0.682 +/- 0.305, P = 0.025, general estimation equation model) in SARS patients. Survival analysis showed that FPG was independently associated with an increased hazard ratio (HR) of mortality (HR = 1.1, 95% CI 1.0, 1.1, P = 0.001) and hypoxia (HR = 1.1, 95% CI 1.0, 1.1, P = 0.002) after controlling for age and gender.

CONCLUSIONS

A known history of diabetes and ambient hyperglycaemia were independent predictors for death and morbidity in SARS patients. Metabolic control may improve the prognosis of SARS patients.

Therapeutic benefit of intracerebral transplantation of bone marrow stromal cells after cerebral ischemia in rats

We tested the hypothesis that bone marrow stromal cells (MSCs) transplanted into the ischemic boundary zone, survive, differentiate and improve functional recovery after middle cerebral artery occlusion (MCAo). MSCs were harvested from adult rats and cultured with or without nerve growth factor (NGF). For cellular identification, MSCs were prelabeled with bromodeoxyuridine (BrdU). Rats (n=24) were subjected to 2 h of MCAo, received grafts at 24 h and were euthanized at 14 days after MCAo. Test groups consisted of: (1) control-MCAo alone (n=8); (2) intracerebral transplantation of MSCs (n=8); (3) intracerebral transplantation of MSCs cultured with NGF (n=8). Immunohistochemistry was used to identify cells from MSCs. Behavioral tests (rotarod, adhesive-removal and modified neurological severity score [NSS]) were performed before and after MCAo. The data demonstrate that MSCs survive, migrate and differentiate into phenotypic neural cells. Significant recovery of somatosensory behavior (p<0.05) and NSS (p<0.05) were found in animals transplanted with MSCs compared with control animals. Animals that received MSCs cultured with NGF displayed significant recovery in motor (p<0.05), somatosensory (p<0.05) and NSS (p<0.05) behavioral tests compared with control animals. Our data suggest that intracerebral transplantation of MSCs may provide a powerful autoplastic therapy for stroke.

GFRalpha1 is an essential receptor component for GDNF in the developing nervous system and kidney

Glial cell line-derived neurotrophic factor (GDNF) is a distant member of the TGFbeta protein family that is essential for neuronal survival and renal morphogenesis. We show that mice who are deficient in the glycosyl-phosphatidyl inositol (GPI) -linked protein GFRalpha1 (GDNFRalpha) display deficits in the kidneys, the enteric nervous system, and spinal motor and sensory neurons that are strikingly similar to those of the GDNF- and Ret-deficient mice. GFRalpha1-deficient dopaminergic and nodose sensory ganglia neurons no longer respond to GDNF or to the structurally related protein neurturin (NTN) but can be rescued when exposed to GDNF or neurturin in the presence of soluble GFRalpha1. In contrast, GFRalpha1-deficient submandibular parasympathetic neurons retain normal response to these two factors. Taken together with the available genetic and biochemical data, these findings support the idea that GFRalpha1 and the transmembrane tyrosine kinase Ret are both necessary receptor components for GDNF in the developing kidney and nervous system, and that GDNF and neurturin can mediate some of their activities through a second receptor.

Spinal cord injury in rat: treatment with bone marrow stromal cell transplantation

We tested the hypothesis that transplantation of bone marrow stromal cells (MSCs) into the spinal cord after a contusion injury promotes functional outcome. Rats (n = 31) were subjected to a weight driven implant injury. MSCs or phosphate buffered saline was injected into the spinal cord 1 week after injury. Sections of tissue were analyzed by double-labeled immunohistochemistry for MSC identification. Functional outcome measurements using the Basso-Beattie-Bresnehan score were performed weekly to 5 weeks post-injury. The data indicate significant improvement in functional outcome in animals treated with MSC transplantation compared to control animals. Scattered cells derived from MSCs expressed neural protein markers. These data suggest that transplantation of MSCs may have a therapeutic role after spinal cord injury.

Differences in the prospective association between individual plasma phospholipid saturated fatty acids and incident type 2 diabetes: the EPIC-InterAct case-cohort study

BACKGROUND

Conflicting evidence exists regarding the association between saturated fatty acids (SFAs) and type 2 diabetes. In this longitudinal case-cohort study, we aimed to investigate the prospective associations between objectively measured individual plasma phospholipid SFAs and incident type 2 diabetes in EPIC-InterAct participants.

METHODS

The EPIC-InterAct case-cohort study includes 12,403 people with incident type 2 diabetes and a representative subcohort of 16,154 individuals who were selected from a cohort of 340.234 European participants with 3·99 million person-years of follow-up (the EPIC study). Incident type 2 diabetes was ascertained until Dec 31, 2007, by a review of several sources of evidence. Gas chromatography was used to measure the distribution of fatty acids in plasma phospholipids (mol%); samples from people with type 2 diabetes and subcohort participants were processed in a random order by centre, and laboratory staff were masked to participant characteristics. We estimated country-specific hazard ratios (HRs) for associations per SD of each SFA with incident type 2 diabetes using Prentice-weighted Cox regression, which is weighted for case-cohort sampling, and pooled our findings using random-effects meta-analysis.

FINDINGS

SFAs accounted for 46% of total plasma phospholipid fatty acids. In adjusted analyses, different individual SFAs were associated with incident type 2 diabetes in opposing directions. Even-chain SFAs that were measured (14:0 [myristic acid], 16:0 [palmitic acid], and 18:0 [stearic acid]) were positively associated with incident type 2 diabetes (HR [95% CI] per SD difference: myristic acid 1·15 [95% CI 1·09-1·22], palmitic acid 1·26 [1·15-1·37], and stearic acid 1·06 [1·00-1·13]). By contrast, measured odd-chain SFAs (15:0 [pentadecanoic acid] and 17:0 [heptadecanoic acid]) were inversely associated with incident type 2 diabetes (HR [95% CI] per 1 SD difference: 0·79 [0·73-0·85] for pentadecanoic acid and 0·67 [0·63-0·71] for heptadecanoic acid), as were measured longer-chain SFAs (20:0 [arachidic acid], 22:0 [behenic acid], 23:0 [tricosanoic acid], and 24:0 [lignoceric acid]), with HRs ranging from 0·72 to 0·81 (95% CIs ranging between 0·61 and 0·92). Our findings were robust to a range of sensitivity analyses.

INTERPRETATION

Different individual plasma phospholipid SFAs were associated with incident type 2 diabetes in opposite directions, which suggests that SFAs are not homogeneous in their effects. Our findings emphasise the importance of the recognition of subtypes of these fatty acids. An improved understanding of differences in sources of individual SFAs from dietary intake versus endogenous metabolism is needed.

FUNDING

EU FP6 programme, Medical Research Council Epidemiology Unit, Medical Research Council Human Nutrition Research, and Cambridge Lipidomics Biomarker Research Initiative.

An optical supernova associated with the X-ray flash XRF 060218

Long-duration gamma-ray bursts (GRBs) are associated with type Ic supernovae that are more luminous than average and that eject material at very high velocities. Less-luminous supernovae were not hitherto known to be associated with GRBs, and therefore GRB-supernovae were thought to be rare events. Whether X-ray flashes--analogues of GRBs, but with lower luminosities and fewer gamma-rays--can also be associated with supernovae, and whether they are intrinsically 'weak' events or typical GRBs viewed off the axis of the burst, is unclear. Here we report the optical discovery and follow-up observations of the type Ic supernova SN 2006aj associated with X-ray flash XRF 060218. Supernova 2006aj is intrinsically less luminous than the GRB-supernovae, but more luminous than many supernovae not accompanied by a GRB. The ejecta velocities derived from our spectra are intermediate between these two groups, which is consistent with the weakness of both the GRB output and the supernova radio flux. Our data, combined with radio and X-ray observations, suggest that XRF 060218 is an intrinsically weak and soft event, rather than a classical GRB observed off-axis. This extends the GRB-supernova connection to X-ray flashes and fainter supernovae, implying a common origin. Events such as XRF 060218 are probably more numerous than GRB-supernovae.