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Hemophagocytic lymphohistiocytosis (HLH) is a rare inflammatory disorder with a poor prognosis for affected individuals. To find a means of suppressing the clinical phenotype, we investigated the cellular and molecular mechanisms leading to HLH in Unc13djinx/jinxmice, in which cytolytic function of NK and CD8+T cells is impaired. Unc13djinx/jinxmutants infected with lymphochoriomeningitis virus (LCMV) present typical clinical features of HLH, including splenomegaly, elevated serum IFNγ, and anemia. Proteins mediating cell-cell contact, cytokine signaling or Toll-like receptor (TLR) signaling were analyzed. We show that neither the integrin CD18, which is involved in adhesion between antigen-presenting cells and effector T cells, nor tumor necrosis factor (TNF) made nonredundant contributions to the disease phenotype. Disruption of IFNγ signaling reduced immune cell activation in Unc13djinx/jinxmice, but also resulted in uncontrolled viral proliferation and exaggerated release of inflammatory cytokines. Abrogating the function of myeloid differentiation primary response gene 88 (MyD88) in Unc13djinx/jinxmice suppressed immune cell activation and controlled cytokine production in an IL-1 receptor 1 (IL-1R1)–independent way. Our findings implicate MyD88 as the key initiator of myeloid and lymphoid proliferation in HLH, and suggest that blockade of this signaling molecule may reduce immunopathology in patients.

Natural killer (NK) cells are innate immune cells that express members of the leukocyte β2 integrin family in humans and mice. These CD11/CD18 heterodimers play critical roles in leukocyte trafficking, immune synapse formation, and costimulation. The cell-surface expression of one of these integrins, CD11b/CD18, is also recognized as a major marker of mouse NK-cell maturation, but its function on NK cells has been largely ignored. Using N-ethyl-N-nitrosourea (ENU) mutagenesis, we generated a mouse carrying an A → T transverse mutation in the Itgb2gene, resulting in a mutation that prevented the cell-surface expression of CD18 and its associated CD11a, CD11b, and CD11c proteins. We show that β2 integrin–deficient NK cells have a hyporesponsive phenotype in vitro, and present an alteration of their in vivo developmental program characterized by a selective accumulation of c-kit+cells. NK-cell missing-self recognition was partially altered in vivo, whereas the early immune response to mouse cytomegalovirus (MCMV) infection occurred normally in CD18-deficient mice. Therefore, β2 integrins are required for optimal NK-cell maturation, but this deficiency is partial and can be bypassed during MCMV infection, highlighting the robustness of antiviral protective responses.

Small intestinal CD103+ dendritic cells (DCs) have the selective ability to promote de novo generation of regulatory T cells via the production of retinoic acid (RA). Considering that aldehyde dehydrogenase (ALDH) activity controls the production of RA, we used a flow cytometry–based assay to measure ALDH activity at the single-cell level and to perform a comprehensive analysis of the RA-producing DC populations present in lymphoid and nonlymphoid mouse tissues. RA-producing DCs were primarily of the tissue-derived, migratory DC subtype and can be readily found in the skin and in the lungs as well as in their corresponding draining lymph nodes. The RA-producing skin-derived DCs were capable of triggering the generation of regulatory T cells, a finding demonstrating that the presence of RA-producing, tolerogenic DCs is not restricted to the intestinal tract as previously thought. Unexpectedly, the production of RA by skin DCs was restricted to CD103− DCs, indicating that CD103 expression does not constitute a “universal” marker for RA-producing mouse DCs. Finally, Toll-like receptor (TLR) triggering or the presence of a commensal microflora was not essential for the induction of ALDH activity in the discrete ALDH+ DC subsets that characterize tissues constituting environmental interfaces.

Small intestinal CD103+dendritic cells (DCs) have the selective ability to promote de novo generation of regulatory T cells via the production of retinoic acid (RA). Considering that aldehyde dehydrogenase (ALDH) activity controls the production of RA, we used a flow cytometry–based assay to measure ALDH activity at the single-cell level and to perform a comprehensive analysis of the RA-producing DC populations present in lymphoid and nonlymphoid mouse tissues. RA-producing DCs were primarily of the tissue-derived, migratory DC subtype and can be readily found in the skin and in the lungs as well as in their corresponding draining lymph nodes. The RA-producing skin-derived DCs were capable of triggering the generation of regulatory T cells, a finding demonstrating that the presence of RA-producing, tolerogenic DCs is not restricted to the intestinal tract as previously thought. Unexpectedly, the production of RA by skin DCs was restricted to CD103−DCs, indicating that CD103 expression does not constitute a “universal” marker for RA-producing mouse DCs. Finally, Toll-like receptor (TLR) triggering or the presence of a commensal microflora was not essential for the induction of ALDH activity in the discrete ALDH+DC subsets that characterize tissues constituting environmental interfaces.

ABSTRACTThe building of egyptian pyramids still remains today an enigma. None of the present theories can satisfy scientists or practitioners of the art of building and offer any convincing evidence. Based on in situ observations, geological constrains and basics of the art of buildings, we suggest a global building system called “pyramidal growth” which confirms the writings of Herodotus and can be placed in a “technical continuum”. We focus in particular on the Kheops' pyramid, the most enigmatic one because of its internal design, but actually and paradoxically the most revealing of the pyramids' constructive system.

Innate immunity is inherited and is, therefore, particularly susceptible to analysis by classical genetic methods. The ‘phenotype first’ approach has already revealed the principal receptors of the innate immune system as well as several essential signalling intermediates. It has recently emerged that innate resistance to mouse cytomegalovirus (MCMV) infection depends upon a large number of host genes with non-redundant functions; hence, random germline mutagenesis frequently causes susceptibility to this pathogen. Approximately one in 30 pedigrees derived from N-ethyl-N-nitrosourea-mutagenised progenitors bears a recessive mutation that disrupts resistance to MCMV. Moreover, many of the genes required for resistance to MCMV will undoubtedly prove to have broad roles in immunity, creating resistance to many other microbes. The forward genetics approach offers an excellent opportunity to identify many of the key components of the innate immune system.

flake (flk), an N-ethyl-N-nitrosourea-induced recessive germ line mutation of C57BL/6 mice, impairs the clearance of skin infections by Streptococcus pyogenes and Staphylococcus aureus, gram-positive pathogens that elicit innate immune responses by activating Toll-like receptor 2 (TLR2) (K. Takeda and S. Akira, Cell. Microbiol. 5:143-153, 2003). Positional cloning and sequencing revealed that flk is a novel allele of the stearoyl coenzyme A desaturase 1 gene (Scd1). flake homozygotes show reduced sebum production and are unable to synthesize the monounsaturated fatty acids (MUFA) palmitoleate (C16:1) and oleate (C18:1), both of which are bactericidal against gram-positive (but not gram-negative) organisms in vitro. However, intradermal MUFA administration to S. aureus-infected mice partially rescues the flake phenotype, which indicates that an additional component of the sebum may be required to improve bacterial clearance. In normal mice, transcription of Scd1—a gene with numerous NF-κB elements in its promoter—is strongly and specifically induced by TLR2 signaling. Similarly, the SCD1 gene is induced by TLR2 signaling in a human sebocyte cell line. These observations reveal the existence of a regulated, lipid-based antimicrobial effector pathway in mammals and suggest new approaches to the treatment or prevention of infections with gram-positive bacteria.

We present a neutral lipopolythiourea (DTTU) as a potential DNA-binding agent. Light scattering experiments showed that mixing a lipopolythiourea with dipalmitoylphosphatidylcholine (DPPC/DTTU) led to small particles with sizes ranging from 100 to 150 nm at optimum conditions. Setting a fixed DNA amount, an increasing amount of DTTU/DPPC or DPPC lipids was added. Particle size increased only with DTTU/DPPC, indicating that interaction occurred between the DTTU/DPPC particles and DNA. In the same way, only DTTU/DPPC limited the ethidium bromide accessibility to plasmid DNA. These data suggest that DTTU/DPPC liposomes associate to DNA, which was confirmed by agarose gel experiments. To prove the active part of the DTTU lipid itself in DNA compaction, pegoylated-lipid was used. Cholesterol-PEG2000 alone was not able to condense DNA. In contrast, DTTU/PEG-cholesterol was able to retain plasmid DNA on an agarose gel. In vivo injection of DTTU/DPPC/complexes was studied. Circulation time increase for noncationic particles as compared to cationic. More obvious was the lack of nonspecific accumulation in the lung, where a gain of 3 to 40 fold was measured.

This study analysed effects of a simulated shade treatment on interactions among reproductive sinks, using pruned (mono-culm) plants in growth chambers. Plants were grown under non-limiting water supply and 600 $\mu$mol$\cdot$m$^{-2}$ $\cdot$s$^{-1}$ PAR, reduced by 40% to simulate shade. Shade was imposed from 7th anthesis onwards, and plant transpiration, dw distribution and phenology were monitored. An index of apparent competition for assimilates (IAC) was calculated by dividing boll load by plant growth rate. Within the inflorescence, shading affected all components of a cascade of events determining sink capacity, including carpel growth, seed number, boll abscission, final seed-cotton dw and partitioning between grain and fibre. In addition to sink down-sizing (abscission, seed number), shade also increased boll growth duration, spreading the demand for assimilates over time. Fibre quality was poor in such situations. Shade also reduced boll appearance rates, thus limiting the number of competing sinks. Organ appearance rates, boll duration and abscission rates were correlated with IAC. The future use of an IAC in the analysis and prediction of sink behaviour in complex plant systems is discussed.

A small, high‐temperature superconducting (HTS) surface coil was used to improve the signal‐to‐noise ratio (SNR) for in vivo human skin microscopy at 1.5 T. The internal noise of the conventional copper coil limits the SNR for this application. Inductive measurements of the HTS coil parameters indicated that at 77 K its internal noise contributed about 4% of the total noise, and the predicted SNR gain was about 3.2‐fold over that of a room‐temperature copper coil. In vivo images of the human skin produced with the HTS coil showed highly resolved details and a 3.7‐fold improvement in SNR over that obtained with the room‐temperature copper coil. Magn Reson Med 45:376–382, 2001. © 2001 Wiley‐Liss, Inc.

Two DNA molecules complementary to human liver mRNA coding for the α-subunit of the stimulatory regulatory component G sof adenylyl cyclase were cloned. One of the two forms is a full-length cDNA of 1614 nucleotides plus a poly(A) tail of 59 nucleotides. The deduced sequence of 394 amino acids encoded by its open reading frame is essentially identical to that of the α-subunits of G sidentified by molecular cloning from bovine adrenals, bovine brain and rat brain. Two independent clones of the other type of cDNA were isolated. Both were incomplete, beginning within the open reading frame coding for the α spolypeptide. One codes for amino acids 5 through 394 and the other for amino acids 48 through 394 of the above described cDNA of 1614 nucleotides, and both have the identical 3'-untranslated sequence. They differ from the first cDNA, however, in that they lack a stretch of 42 nucleotides (numbers 214 through 255) and have nucleotides 213 (G) and 256 (G) replaced with C and A, respectively. This results in a predicted amino acid composition of another α-subunit of G sthat is shorter by 14 amino acids and contains two substitutions (Asp for Glu and Ser for Gly) at the interface between the deletion and the unchanged sequence. We call the smaller subunit α s1and the larger α s2. This is the first demonstration of a structural heterogeneity in α s, subunits that is due to a difference in amino acid sequence.

The aim of this study was to compare the yield and seed production of well irrigated indeterminate pea and soybean in relation to N nutrition and plant N status at the beginning of seed-filling (BSF stage). Plant N status was characterized by a N nutrition index (NNI). A large range in nitrogen accumulation and dinitrogen fixation was obtained by means of N fertilizer application (pea and soybean), inoculation (soybean) and increasing soil compaction (pea) carried out at various sites and in different years. Pea displayed a higher dinitrogen fixation ability than soybean and accumulated a larger proportion of nitrogen prior to the BSF stage. The nitrogen requirement for the production of 1 ton of soybean seed was twice that for pea and its maximum grain yield was half that of pea. In response to increasing NNI at the BSF stage, the two species showed differences in seed establishment and seedfilling. These differences in yield response to the treatments are discussed in relation to the seed composition and N nutrition of both species.

Two DNA molecules complementary to human liver mRNA coding for the α‐subunit of the stimulatory regulatory component Gsof adenylyl cyclase were cloned. One of the two forms is a full‐length cDNA of 1614 nucleotides plus a poly(A) tail of 59 nucleotides. The deduced sequence of 394 amino acids encoded by its open reading frame is essentially identical to that of the α‐subunits of Gsidentified by molecular cloning from bovine adrenals, bovine brain and rat brain. Two independent clones of the other type of cDNA were isolated. Both were incomplete, beginning within the open reading frame coding for the αspolypeptide. One codes for amino acids 5 through 394 and the other for amino acids 48 through 394 of the above described cDNA of 1614 nucleotides, and both have the identical 3'‐untranslated sequence. They differ from the first cDNA, however, in that they lack a stretch of 42 nucleotides (numbers 214 through 255) and have nucleotides 213 (G) and 256 (G) replaced with C and A, respectively. This results in a predicted amino acid composition of another α‐subunit of Gsthat is shorter by 14 amino acids and contains two substitutions (Asp for Glu and Ser for Gly) at the interface between the deletion and the unchanged sequence. We call the smaller subunit αs1and the larger αs2. This is the first demonstration of a structural heterogeneity in αs, subunits that is due to a difference in amino acid sequence.

The development of solid-gas thermochemical transformers requires the design and the construction of demonstration machines which could not exist without simulation models, allowing the dimensioning of fixed-bed solid-gas reactors. All of the models developed so far are based on a dynamic modelling of the process describing the temporal evolution of the principal elements of which the machine consists. This approach to dimensioning is certainly better adapted to the discontinuous and unstationary working mode of these machines. However, the dimensioning of the machine becomes a very complex and time consuming operation.

Among the techniques of cerebral protection, the use of controlled arterial hypertension is based on the following arguments : 1) Cerebral ischaemia is the final common pathway of any insult to the brain, particularly through secondary lesions. Causes of secondary cerebral lesions include pressure under the brain retractors, temporary clipping, arterial hypotension, hypoxaemia, anaemia and hypercapnia. 2) In the brain, the critical lower value for cerebral blood flow is around 25 mL · 100 g−1 · min−1, under which two types of ischaemic areas can be defined : the penlucida type where cerebral function is abolished, without permanent cerebral lesion and the penumbra type where cerebral tissue recovers only if flow is rapidly restored. In the latter case the duration of ischaemia is very important. 3) Cerebral blood flow is maintained stable within a large range of variations of mean arterial pressure through the autoregulation mechanisms, which is based on vasomotricity of the cerebral circulation, which implies major variations in cerebral blood volume. However, autoregulation needs several dozens of seconds to be achieved. Therefore, sudden variations in mean arterial pressure are associated with short lasting but major variations in cerebral blood volume. 4) In case of increased intracranial pressure, a decrease in cerebral perfusion pressure causes cerebral vasodilation through the autoregulation mechanism, with an increase in cerebral blood volume which will, in turn, increase intracranial pressure and thus decrease cerebral perfusion pressure, and so on. This is the vasodilatory cascade. The therapeutical increase in mean arterial pressure will correct this phenomenon and decrease intracranial pressure. This is called the vasoconstrictive cascade. 5) In case of vascular occlusion by vasospasm, extrinsic compression or during temporary clipping, cerebral protection may be based on the collateral vessels near the ischaemic area and also on vascular anastomoses inside the circle of Willis. Following Poiseuille's law, as vasodilation is already maximal distally to the stenosis, the major factor of vascular resistance is no longer the radius of the vessel, but its length. Accordingly, the increase in perfusion pressure will improve the local flow and participate in prevention or treatment of an ischaemic event. Indeed, the increase, although modest, of the local flow may be sufficient to switch from an ischaemia of penumbra type to a penlucida type. Finally, controlled arterial hypertension 1) implies to achieve the optimal cerebral perfusion pressure in order to create the vasoconstrictive cascade under cover of intracranial pressure monitoring and 2) helps to decrease the ischaemic risk secondary to vasospasm, for example by achieving a mean arterial pressure between 70 and 100 mmHg before clipping and between 100 and 120 mmHg after clipping. To obtain this level of pressure, phenylephrine, noradrenaline and dopamine are the agents of choice, as they are free of harmful effects on the cerebral circulation.

S-adenosylmethionine decarboxylase (AdoMetDC) is a key enzyme in polyamine biosynthesis. The human genome contains at least two loci for the AdoMetDC gene (AMD), one of which (AMD1) has previously been mapped to chromosome 6 and the other (AMD2) to the X chromosome. The locus on chromosome 6 is the transcriptionally active gene. We now report characterization of the AMD2 locus (GenBank Accession No. U02035) on the X chromosome, which contains sequences that cross-hybridize with human AdoMetDC cDNA. This DNA lacks all of the introns present in AMD1 and has numerous mutations in the protein-coding region. Its overall nucleotide sequence identity with AdoMetDC cDNA is about 90%. AMD2 is therefore a processed pseudogene, which, because of multiple mutations, cannot be translated to an active AdoMetDC enzyme, even if it were transcribed. Chromosomal loci for human AMD sequences were determined by in situ hybridization to metaphase chromosomes, with genomic DNAs from the active gene and the pseudogene loci as probes. AMD1 was localized to chromosome region 6q21→q22 and AMD2 to band Xq28.

Production of thymidine kinase (TK) protein parallels the onset of DNA synthesis during the cell cycle. This process is regulated at transcriptional, posttranscriptional, and translational levels to cause a 40- to 50-fold increase in cytosolic enzymatic activity as cells progress from G1 to S phase. Transcriptional activation of the mouse TK gene through the cell cycle is dependent upon previously characterized cis elements of the proximal promoter, called MT1, MT2, and MT3, that bind at least two different complexes: TKE during the transition of cells from quiescence (G0) to G1, and Yi later at the G1/S boundary. To identify the transcription factors involved in this regulation, we screened a mouse fibroblast cDNA expression library with a labeled MT3 oligonucleotide probe and isolated a clone that encodes Egr-1, an immediate-early transcription factor, whose expression is regulated by serum or growth factors during the G0-to-G1 transition when cells reenter the cell cycle. Electrophoretic mobility shift assays demonstrate that Egr-1 is involved in the TKE complex that binds to the MT3 element and that expression of Egr-1 induces transcription of a mouse TK-chloramphenicol acetyltransferase reporter in transient transfections. These results suggest a role for Egr-1 in regulating expression of the TK gene at the G0-to-G1 transition.

In order to understand the structure and regulation of S-adenosylmethionine decarboxylase, cDNA clones encoding this enzyme have been isolated from rat prostate and human fibroblast cDNA libraries. The authenticity of the cDNAs was verified by: (a) transfecting the Chinese hamster ovary cells with the human cDNA in the pcD vector which resulted in a transient 10-20-fold increase in S-adenosylmethionine decarboxylase activity in recipient cells; and (b) translating the mRNA formed by transcription of the cDNA insert in a reticulocyte lysate and recording an increase in S-adenosylmethionine decarboxylase activity. The amino acid sequences deduced from the cDNAs indicate that the human proenzyme for this protein contains 334 amino acids and has a molecular weight of 38,331 whereas the rat proenzyme contains 333 amino acid residues. The human and rat enzymes are very similar having only 11 amino acid differences and the cDNAs are also closely related showing over 90% homology in the 1617-nucleotide overlap which was sequenced. A further indication of the highly conserved nature of mammalian S-adenosylmethionine decarboxylases is that the amino acid sequences deduced from the human and the rat cDNAs contained peptide sequences identical to those previously reported for the purified bovine enzyme. In vitro transcription/translation experiments showed that the proenzyme is converted to two polypeptides of molecular weights about 32,000 and 6,000 in a processing reaction which generates the prosthetic pyruvate group and that the final enzyme contains both polypeptides. Two forms of S-adenosylmethionine decarboxylase mRNA (2.1 and about 3.4-3.6 kilobases) are present in human and rodent tissues and may originate from the utilization of two different polyadenylation signals. Southern blots of rat genomic DNA indicated that the S-adenosylmethionine decarboxylase gene belongs to a multigene family. Depletion of cellular polyamines by inhibitors or ornithine decarboxylase or the aminopropyltransferases led to an increase in the content of S-adenosylmethionine decarboxylase protein and mRNA, but the elevation in the mRNA was not sufficient to account for all of the change in the enzyme level, particularly in cells in which spermine was depleted.

We report the demonstration of intersubband modulators operating at telecommunication wavelengths at room temperature based on GaN/AlN quantum wells. We first investigate electro-optical modulators making use of electron tunneling in coupled quantum wells. Electro-absorption modulation with opposite sign induced by the electron tunneling between the reservoir and active quantum wells is observed at λ 1.3–1.6 µm and λ 2.2 µm. We show that by reducing the mesa size down to 15 × 15 µm2, optical modulation bandwidth as large as 3 GHz can be obtained. We then investigate waveguide intersubband modulators relying on the depletion of the ground electronic state of a 3 quantum well active region. Modulation depths as large as 14 dB in the wavelength range of 1.2–1.6 µm are obtained under –9 V/7 V voltage swing. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The measurement of high dielectric constants materials in a coaxial line, using an automatic network analyser (ANA), must take the actual diameter of the sample into consideration. The error on the measured &Vegr;r value may be approximated by the fractional diameter deviation times &Vegr;r7. A correction method is proposed.

High repetition rate picosecond pulses with low uncorrelated timing jitter (down to ~0.25 ps) have been generated at 1.55 µm from gain- and Q-switched InGaAsP lasers without external feedback. Experiments were carried out at multi-gigahertz frequencies on one- and two-section devices; the timing jitter was estimated from spectral measurements. Sub-picosecond values were found above ~5 GHz for optimally-biased one-section DFB lasers in gain-switching. Values more than two times lower were obtained from Q-switched quantum well two-section lasers, with RF modulation applied to a fast absorber section.

HEMT electrostatic capacitances are determined with a 2-D finite element solver according to the device geometry. The calculation is compared with measurements on recessed ultrasubmicrometre rectangular gate and T-gate pseudomorphic and standard HEMTs on GaAs.

When coplanar probes are used, the open circuit reflection standard in the SOLT calibration technique is usually the most questionable of the four. This standard is described in the ‘cal kit’ as a capacitance, the value of which is determined in a ‘cut and try’ way. A more direct method is proposed in this Letter.

0.2μm Al0.48In0.52As/Ga0.47In0.53As LMHEMT on InP with an undoped GaInAs layer to reduce gate leakage have been realised and their DC and RF properties have been investigated cryogenic temperatures. The cutoff maximum frequencies oscillation Fmax up to 260 Hz are extrapolated at 50 K from the maximum unilateral gain (MUG) determined using S parameters measured up to 40 GHz. Evolution of gate leakage current and RF characteristics against gate and drain biases are presented between 50 and 300 K.