Differentiation tracing identifies hematopoietic regeneration from multipotent progenitors but not stem cells

Hematopoietic stem cells (HSCs) and multipotent progenitors (MPPs) generate the immune system in development, and contribute to its maintenance under steady-state conditions. How stem and progenitor cells respond to increased demand for mature cells upon injury is a fundamental question of stem cell biology. Several studies of murine hematopoiesis have reported increased proliferation of HSCs in situ when exposed to inflammatory stimuli, which has been taken as a proxy for increased HSC differentiation. Such surplus generation of HSC may fuel enhanced HSC differentiation or, alternatively, maintain HSC cellularity in the face of increased cell death without enhanced HSC differentiation. This key question calls for direct measurements of HSC differentiation in their natural niches in vivo. Here, we review work that quantifies native HSC differentiation by fate mapping and mathematical inference. Recent differentiation tracing studies show that HSC do not increase their differentiation rate upon a wide range of challenges, including systemic bacterial infection (sepsis), blood loss, and transient or persistent ablation of specific mature immune cells. By contrast, MPPs differentiate more rapidly in response to systemic infection to accelerate the production of myeloid cells. These new in vivo data identify MPPs as a major source of hematopoietic regeneration; HSCs might not contribute to regeneration while remaining protected.

Flt3- and Tie2-Cre tracing identifies regeneration in sepsis from multipotent progenitors but not hematopoietic stem cells

In response to infections and stress, hematopoiesis rapidly enhances blood and immune cell production. The stage within the hematopoietic hierarchy that accounts for this regeneration is unclear under natural conditions in vivo. We analyzed by differentiation tracing, using inducible Tie2- or Flt3-driven Cre recombinase, the roles of mouse hematopoietic stem cells (HSCs) and multipotent progenitors (MPPs). During polymicrobial sepsis, HSCs responded transcriptionally and increased their proliferation and cell death, yet HSC differentiation rates remained at steady-state levels. HSC differentiation was also independent from the ablation of various cellular compartments-bleeding, the antibody-mediated ablation of granulocytes or B lymphocytes, and genetic lymphocyte deficiency. By marked contrast, the fate mapping of MPPs in polymicrobial sepsis identified these cells as a major source for accelerated myeloid cell production. The regulation of blood and immune cell homeostasis by progenitors rather than stem cells may ensure a rapid response while preserving the integrity of the HSC population.

Quantum-inspired multicore optical fiber

We introduce a new, to the best of our knowledge, type of multicore optical fiber having a quantum-inspired network topology and unique spectral features. Particularly, the connectivity between the cores is generated by unfolding a circular array of coupled quantum oscillators in Fock space. We show that in such a fiber geometry, the eigenvalues of the optical supermodes exhibit partial degeneracy and form a ladder. In turn, this leads to revival dynamics, allowing for a periodic re-imaging of the input intensity. As an example, we present a realistic design with six cores in silica glass platforms.

Reconciling Flux Experiments for Quantitative Modeling of Normal and Malignant Hematopoietic Stem/Progenitor Dynamics

Hematopoiesis serves as a paradigm for how homeostasis is maintained within hierarchically organized cell populations. However, important questions remain as to the contribution of hematopoietic stem cells (HSCs) toward maintaining steady state hematopoiesis. A number of in vivo lineage labeling and propagation studies have given rise to contradictory interpretations, leaving key properties of stem cell function unresolved. Using processed flow cytometry data coupled with a biology-driven modeling approach, we show that in vivo flux experiments that come from different laboratories can all be reconciled into a single unifying model, even though they had previously been interpreted as being contradictory. We infer from comparative analysis that different transgenic models display distinct labeling efficiencies across a heterogeneous HSC pool, which we validate by marker gene expression associated with HSC function. Finally, we show how the unified model of HSC differentiation can be used to simulate clonal expansion in the early stages of leukemogenesis.

Ontogeny of arterial macrophages defines their functions in homeostasis and inflammation

Arterial macrophages have different developmental origins, but the association of macrophage ontogeny with their phenotypes and functions in adulthood is still unclear. Here, we combine macrophage fate-mapping analysis with single-cell RNA sequencing to establish their cellular identity during homeostasis, and in response to angiotensin-II (AngII)-induced arterial inflammation. Yolk sac erythro-myeloid progenitors (EMP) contribute substantially to adventitial macrophages and give rise to a defined cluster of resident immune cells with homeostatic functions that is stable in adult mice, but declines in numbers during ageing and is not replenished by bone marrow (BM)-derived macrophages. In response to AngII inflammation, increase in adventitial macrophages is driven by recruitment of BM monocytes, while EMP-derived macrophages proliferate locally and provide a distinct transcriptional response that is linked to tissue regeneration. Our findings thus contribute to the understanding of macrophage heterogeneity, and associate macrophage ontogeny with distinct functions in health and disease.

Arterial macrophages develop from either yolk sac or bone marrow progenitors. Here, the author show that ageing-induced reduction of arterial macrophages is not replenished by bone marrow-derived cells, but under inflammatory conditions circulating monocytes are recruited to maintain homeostasis, while arterial macrophages of yolk sac origin carry out tissue repair.

Resolving Fates and Single-Cell Transcriptomes of Hematopoietic Stem Cell Clones by PolyloxExpress Barcoding

Lineage tracing reveals hematopoietic stem cell (HSC) fates, while single-cell RNA sequencing identifies snapshots of HSC transcriptomes. To obtain information on fate plus transcriptome in the same cell, we developed the PolyloxExpress allele, enabling Cre-recombinase-dependent RNA barcoding in situ. Linking fates to single HSC transcriptomes provided the information required to identify transcriptional signatures of HSC fates, which were not apparent in single-HSC transcriptomes alone. We find that differentiation-inactive, multilineage, and lineage-restricted HSC clones reside in distinct regions of the transcriptional landscape of hematopoiesis. Differentiation-inactive HSC clones are closer to the origin of the transcriptional trajectory, yet they are not characterized by a quiescent gene signature. Fate-specific gene signatures imply coherence of clonal HSC fates, and HSC output toward short-lived lineage progenitors indicates stability of HSC fates over time. These combined analyses of fate and transcriptome under physiological conditions may pave the way toward identifying molecular determinants of HSC fates.

Nonadditive Enhancement of Nonequilibrium Atom-Surface Interactions

The motion-induced drag force acting on a particle moving parallel to an arrangement of N objects is analyzed. Particular focus is placed on the nonequilibrium statistics of the interaction and on the interplay between the system's geometry and the different dissipative processes occurring in realistic setups. We show that the drag force can exhibit a markedly nonadditive enhancement with respect to the corresponding additive approximation. The specific case of a planar cavity-a relevant configuration for many experiments-is calculated, showing an enhancement of about one order of magnitude. This and similar configurations are of significant potential interest for future measurements that aim to detect the drag force.

Quantum Rolling Friction

An atom moving in a vacuum at constant velocity and parallel to a surface experiences a frictional force induced by the dissipative interaction with the quantum fluctuations of the electromagnetic field. We show that the combination of nonequilibrium dynamics, the anomalous Doppler effect, and spin-momentum locking of light mediates an intriguing interplay between the atom's translational and rotational motion. In turn, this deeply affects the drag force in a way that is reminiscent of classical rolling friction. Our fully non-Markovian and nonequilibrium description reveals counterintuitive features characterizing the atom's velocity-dependent rotational dynamics. These results prompt interesting directions for tuning the interaction and for investigating nonequilibrium dynamics as well as the properties of confined light.

Akuter blutiger Durchfall als Vorstellungsgrund bei einem Hund mit primärem Hypoadrenokortizismus

Ein 7 Jahre alter, männlich-kastrierter Schäferhundmischling wurde wegen akuten blutigen Erbrechens und wässrig-blutigen Durchfalls vorgestellt. Aufgrund klinischer Präsentation, unspezifischer Laborwertveränderungen, unauffälliger Elektrolytwerte und schneller klinischer Besserung auf Infusionstherapie wurde die Diagnose “hämorrhagische Gastroenteritis” (HGE) gestellt. Bei erneuter Vorstellung des Hundes wegen Leistungsschwäche einen Monat später bestanden Elektrolytverschiebungen (Hyperkaliämie und Hyponatriämie), die charakteristisch für einen typischen Hypoadrenokortizismus sind. Mittels ACTH-Stimulationstest wurde eine Unterfunktion der Nebennierenrinde bestätigt. Dieser Fallbericht zeigt, dass sich Patienten in einer Addison-Krise mit akutem hämorrhagischem Durchfall präsentieren können. Durch Erbrechen und Durchfall kann es zu einem Kaliumverlust über den Gastrointestinaltrakt kommen, wodurch typische Elektrolytverschiebungen für einen Morbus Addison verschleiert werden. Im Zweifelsfall sollte bei jedem Patienten mit blutigem Durchfall zum Ausschluss eines Hypoadrenokortizismus eine Bestimmung der basalen Kortisolkonzentration erfolgen.

Polylox barcoding reveals haematopoietic stem cell fates realized in vivo

Developmental deconvolution of complex organs and tissues at the level of individual cells remains challenging. Non-invasive genetic fate mapping1 has been widely used, but the low number of distinct fluorescent marker proteins limits its resolution. Much higher numbers of cell markers have been generated using viral integration sites2, viral barcodes3, and strategies based on transposons4 and CRISPR/Cas9 genome editing5; however, temporal and tissue-specific induction of barcodes in situ has not been achieved. Here we report the development of an artificial DNA recombination locus (termed Polylox) that enables broadly applicable endogenous barcoding based on the Cre-loxP recombination system6,7. Polylox recombination in situ reaches a practical diversity of several hundred thousand barcodes, allowing tagging of single cells. We have used this experimental system, combined with fate mapping, to assess haematopoietic stem cell (HSC) fates in vivo. Classical models of haematopoietic lineage specification assume a tree with few major branches. More recently, driven in part by the development of more efficient single-cell assays and improved transplantation efficiencies, different models have been proposed, in which unilineage priming may occur in mice and humans at the level of HSCs8–10. We have introduced barcodes into HSC progenitors in embryonic mice, and found that the adult HSC compartment is a mosaic of embryo-derived HSC clones, some of which are unexpectedly large. Most HSC clones gave rise to multilineage or oligolineage fates, arguing against unilineage priming, and suggesting coherent usage of the potential of cells in a clone. The spreading of barcodes, both after induction in embryos and in adult mice, revealed a basic split between common myeloid-erythroid development and common lymphocyte development, supporting the long-held but contested view of a tree-like haematopoietic structure.

Detection of Anomalous Cervical Internal Carotid Artery Branches by Colour Duplex Ultrasound

OBJECTIVES

Conventional anatomical descriptions of the cervical internal carotid artery (ICA) report that no branches arise from this segment. However reports of ICA branches exist. The study aim was to determine the prevalence of anomalous branches of the ICA using colour duplex ultrasound (CDU).

METHODS

Four hundred consecutive patients (800 carotid vessels) referred to a tertiary hospital vascular laboratory for investigation of carotid disease were included. A clear differentiation of a low resistive ICA and a high resistive external carotid artery (ECA) waveform was required. CDU was performed on a Philips IU22 ultrasound system with a 9-3 MHz linear array transducer employing a standard carotid imaging protocol. The origin of each ICA branch was identified using B-mode and CDU. Anatomical orientation of ICA branches and distance from bifurcation was recorded and spectral CDU analysis was performed.

RESULTS

Twenty ICA branches, tracking cephaladly, were detected in 16 patients (4%), or 2.5% (20/800) vessels. The median age was 73 years; 50% were female and 50% male. All patients demonstrated a single branch [unilateral anomaly (n = 12 patients), bilateral anomaly (n = 4) patients]. Eighty-five percent arose from the posterior wall of the ICA. The median distance from ICA bifurcation was 4 mm (range 0-18 mm). ICA branch diameters ranged from 1.2 mm to 2.4 mm (median 1.4 mm, mean 1.6 mm). Eighty percent of ICA branches had less than 50% stenosis. Spectral analysis revealed high resistive waveforms in all branches.

CONCLUSIONS

Branches from the ICA exist and can be characterised with CDU. Prevalence in a tertiary hospital referral cohort is 4%. Given their potential clinical implications, standard carotid imaging protocols should consider routine assessment and reporting of ICA branches.

GATA4-dependent organ-specific endothelial differentiation controls liver development and embryonic hematopoiesis

Microvascular endothelial cells (ECs) are increasingly recognized as organ-specific gatekeepers of their microenvironment. Microvascular ECs instruct neighboring cells in their organ-specific vascular niches through angiocrine factors, which include secreted growth factors (angiokines), extracellular matrix molecules, and transmembrane proteins. However, the molecular regulators that drive organ-specific microvascular transcriptional programs and thereby regulate angiodiversity are largely elusive. In contrast to other ECs, which form a continuous cell layer, liver sinusoidal ECs (LSECs) constitute discontinuous, permeable microvessels. Here, we have shown that the transcription factor GATA4 controls murine LSEC specification and function. LSEC-restricted deletion of Gata4 caused transformation of discontinuous liver sinusoids into continuous capillaries. Capillarization was characterized by ectopic basement membrane deposition, formation of a continuous EC layer, and increased expression of VE-cadherin. Correspondingly, ectopic expression of GATA4 in cultured continuous ECs mediated the downregulation of continuous EC-associated transcripts and upregulation of LSEC-associated genes. The switch from discontinuous LSECs to continuous ECs during embryogenesis caused liver hypoplasia, fibrosis, and impaired colonization by hematopoietic progenitor cells, resulting in anemia and embryonic lethality. Thus, GATA4 acts as master regulator of hepatic microvascular specification and acquisition of organ-specific vascular competence, which are indispensable for liver development. The data also establish an essential role of the hepatic microvasculature in embryonic hematopoiesis.

Failure of Local Thermal Equilibrium in Quantum Friction

Recent progress in manipulating atomic and condensed matter systems has instigated a surge of interest in nonequilibrium physics, including many-body dynamics of trapped ultracold atoms and ions, near-field radiative heat transfer, and quantum friction. Under most circumstances the complexity of such nonequilibrium systems requires a number of approximations to make theoretical descriptions tractable. In particular, it is often assumed that spatially separated components of a system thermalize with their immediate surroundings, although the global state of the system is out of equilibrium. This powerful assumption reduces the complexity of nonequilibrium systems to the local application of well-founded equilibrium concepts. While this technique appears to be consistent for the description of some phenomena, we show that it fails for quantum friction by underestimating by approximately 80% the magnitude of the drag force. Our results show that the correlations among the components of driven, but steady-state, quantum systems invalidate the assumption of local thermal equilibrium, calling for a critical reexamination of this approach for describing the physics of nonequilibrium systems.

The Orphan Receptor Tie1 Controls Angiogenesis and Vascular Remodeling by Differentially Regulating Tie2 in Tip and Stalk Cells

Tie1 is a mechanistically poorly characterized endothelial cell (EC)-specific orphan receptor. Yet, Tie1 deletion is embryonic lethal and Tie1 has been implicated in critical vascular pathologies, including atherosclerosis and tumor angiogenesis. Here, we show that Tie1 does not function independently but exerts context-dependent effects on the related receptor Tie2. Tie1 was identified as an EC activation marker that is expressed during angiogenesis by a subset of angiogenic tip and remodeling stalk cells and downregulated in the adult quiescent vasculature. Functionally, Tie1 expression by angiogenic EC contributes to shaping the tip cell phenotype by negatively regulating Tie2 surface presentation. In contrast, Tie1 acts in remodeling stalk cells cooperatively to sustain Tie2 signaling. Collectively, our data support an interactive model of Tie1 and Tie2 function, in which dynamically regulated Tie1 versus Tie2 expression determines the net positive or negative effect of Tie1 on Tie2 signaling.

Tissue-resident macrophages originate from yolk-sac-derived erythro-myeloid progenitors

Most haematopoietic cells renew from adult haematopoietic stem cells (HSCs), however, macrophages in adult tissues can self-maintain independently of HSCs. Progenitors with macrophage potential in vitro have been described in the yolk sac before emergence of HSCs, and fetal macrophages can develop independently of Myb, a transcription factor required for HSC, and can persist in adult tissues. Nevertheless, the origin of adult macrophages and the qualitative and quantitative contributions of HSC and putative non-HSC-derived progenitors are still unclear. Here we show in mice that the vast majority of adult tissue-resident macrophages in liver (Kupffer cells), brain (microglia), epidermis (Langerhans cells) and lung (alveolar macrophages) originate from a Tie2(+) (also known as Tek) cellular pathway generating Csf1r(+) erythro-myeloid progenitors (EMPs) distinct from HSCs. EMPs develop in the yolk sac at embryonic day (E) 8.5, migrate and colonize the nascent fetal liver before E10.5, and give rise to fetal erythrocytes, macrophages, granulocytes and monocytes until at least E16.5. Subsequently, HSC-derived cells replace erythrocytes, granulocytes and monocytes. Kupffer cells, microglia and Langerhans cells are only marginally replaced in one-year-old mice, whereas alveolar macrophages may be progressively replaced in ageing mice. Our fate-mapping experiments identify, in the fetal liver, a sequence of yolk sac EMP-derived and HSC-derived haematopoiesis, and identify yolk sac EMPs as a common origin for tissue macrophages.

Refining the picture of reduced alerting responses in ADHD - a single-trial analysis of event-related potentials

In attention-deficit/hyperactivity disorder (ADHD), a reduced phasic alerting response (event-related potential component P3 to cue stimuli) has been reported for different subtypes and task types in a series of studies. In order to get a refined picture of this attentional deficit, which is based on the analysis of averaged event-related potentials, we studied the distribution of single-trial cue-P3 amplitudes and the relation between the cue-P3 and the neural state (EEG spectral analysis) when expecting the stimulus. Brain electrical activity was recorded in children of different ADHD subtypes (combined type, predominantly inattentive) and typically developing children while conducting the attention network test. In children with ADHD of the combined type, smaller cue-P3 amplitudes in the averaged signal were due to a larger portion of single trials with reduced cue-P3 amplitudes whereas maximum amplitudes did not differ from typically developing children. In this ADHD subtype, larger activity in the upper theta/lower alpha range (5.5-10.5Hz) was strongly associated with the range (difference between 0.9 quantile and 0.1 quantile) of the cue-P3 amplitude in single trials (correlation coefficient r=0.77) indicating a suboptimal neural state before stimulus presentation. In children with ADHD of the predominantly inattentive subtype, single-trial P3 amplitudes were comparable at lower quantiles but maximum amplitudes were reduced. This result pattern indicates an intact triggering of the cue-P3 but a reduced capacity of resource allocation for the predominantly inattentive subtype. Though findings are limited by a relative small sample size, the cue-P3 may be considered as a neurophysiological marker of alerting deficits in ADHD reflecting different underlying mechanisms in ADHD subtypes.

EEG spectral analysis of attention in ADHD: implications for neurofeedback training?

Objective: In children with attention-deficit/hyperactivity disorder (ADHD), an increased theta/beta ratio in the resting EEG typically serves as a rationale to conduct theta/beta neurofeedback (NF) training. However, this finding is increasingly challenged. As NF may rather target an active than a passive state, we studied the EEG in a condition that requires attention.

Methods: In children with ADHD of the DSM-IV combined type (ADHD-C; N = 15) and of the predominantly inattentive type (ADHD-I; N = 9) and in typically developing children (N = 19), EEG spectral analysis was conducted for segments during the attention network test (ANT) without processing of stimuli and overt behavior. Frontal (F3, Fz, F4), central (C3, Cz, C4) and parietal (P3, Pz, P4) electrodes were included in the statistical analysis. To investigate if EEG spectral parameters are related to performance measures, correlation coefficients were calculated.

Results: Particularly in the ADHD-C group, higher theta and alpha activity was found with the most prominent effect in the upper-theta/lower-alpha (5.5–10.5 Hz) range. In the ADHD-I group, a significantly higher theta/beta ratio was observed at single electrodes (F3, Fz) and a tendency for a higher theta/beta ratio when considering all electrodes (large effect size). Higher 5.5–10.5 Hz activity was associated with higher reaction time variability with the effect most prominent in the ADHD-C group. A higher theta/beta ratio was associated with higher reaction times, particularly in the ADHD-I group.

Conclusions: (1) In an attention demanding period, children with ADHD are characterized by an underactivated state in the EEG with subtype-specific differences. (2) The functional relevance of related EEG parameters is indicated by associations with performance (reaction time) measures. (3) Findings provide a rationale for applying NF protocols targeting theta (and alpha) activity and the theta/beta ratio in subgroups of children with ADHD.

Cell competition is a tumour suppressor mechanism in the thymus

Cell competition is an emerging principle underlying selection for cellular fitness during development and disease. Competition may be relevant for cancer, but an experimental link between defects in competition and tumorigenesis is elusive. In the thymus, T lymphocytes develop from precursors that are constantly replaced by bone-marrow-derived progenitors. Here we show that in mice this turnover is regulated by natural cell competition between 'young' bone-marrow-derived and 'old' thymus-resident progenitors that, although genetically identical, execute differential gene expression programs. Disruption of cell competition leads to progenitor self-renewal, upregulation of Hmga1, transformation, and T-cell acute lymphoblastic leukaemia (T-ALL) resembling the human disease in pathology, genomic lesions, leukaemia-associated transcripts, and activating mutations in Notch1. Hence, cell competition is a tumour suppressor mechanism in the thymus. Failure to select fit progenitors through cell competition may explain leukaemia in X-linked severe combined immune deficiency patients who showed thymus-autonomous T-cell development after therapy with gene-corrected autologous progenitors.

[Acute haemorrhagic diarrhoea as a presenting sign in a dog with primary hypoadrenocorticism]

A 7-year-old male castrated mixed breed dog was presented because of acute haemorrhagic vomiting and watery haemorrhagic diarrhoea. According to clinical signs, nonspecific clinicopathological abnormalities, normal electrolytes and a rapid improvement with fluid therapy, haemorrhagic gastroenteritis (HGE) was suspected. One month later the dog was represented with weakness and electrolyte changes characteristic for typical hypoadrenocorticism (hyperkalaemia and hyponatraemia) were found. The tentative diagnosis was confirmed using an ACTH stimulation test. This case report highlights that dogs with hypoadrenocorticism may be presented with acute haemorrhagic diarrhoea. Electrolyte changes characteristic for hypoadrenocorticism may not be present in case of gastrointestinal potassium loss because of vomiting and diarrhoea. To rule out hypoadrenocorticism, a basal cortisol measurement should be performed in every dog with acute haemorrhagic diarrhoea of unknown cause.

Endoscopically visualized lesions, histologic findings, and bacterial invasion in the gastrointestinal mucosa of dogs with acute hemorrhagic diarrhea syndrome

BACKGROUND

Etiology of hemorrhagic gastroenteritis (HGE) syndrome in dogs is unknown and histopathologic and microbial investigations have only been performed post mortem.

OBJECTIVE

To identify characteristic intra vitam endoscopic and histologic mucosal lesions, as well as bacterial species, within the mucosa of dogs with HGE.

ANIMALS

Ten dogs diagnosed with HGE were included. Eleven dogs with gastroduodenoscopy and different intestinal diseases were used as controls for microbial changes. Dogs pretreated with antibiotics or diagnosed with any disease known to cause bloody diarrhea were excluded from the study.

METHODS

In this prospective study, gastrointestinal biopsies were collected from 10 dogs with HGE. Endoscopic and histologic changes were assessed according to WSAVA guidelines. Biopsies from the stomach, duodenum, ileum, and colon were investigated by histology and by immunohistochemistry for the presence of Clostridium spp. and parvovirus. The first duodenal biopsy taken with a sterile forceps was submitted for bacterial culture.

RESULTS

Acute mucosal lesions were only found in the intestines, not in the stomach. Clostridium spp., identified as Clostridium perfringens in 6/9 cases, were detected on the small intestinal mucosa in all dogs with HGE, either by culture or immunohistopathology. In the control group, C. perfringens could only be cultured in one of 11 dogs.

CONCLUSIONS AND CLINICAL IMPORTANCE

The results of this study demonstrate an apparent association between C. perfringens and the occurrence of acute hemorrhagic diarrhea. The term "HGE," which implies the involvement of the stomach, should be renamed as "acute hemorrhagic diarrhea syndrome."

Waveguides in three-dimensional photonic-bandgap materials by direct laser writing and silicon double inversion

Three-dimensional complete photonic-bandgap materials offer unique opportunities regarding the integration of optical waveguide architectures in three dimensions. However, corresponding experimental realizations are truly sparse. Here, we fabricate such waveguides using direct laser writing and a silicon double-inversion procedure. The optical characterization is in good agreement with theoretical calculations, raising hopes that even more complex architectures may soon come into reach.

Fabrication and characterization of silicon woodpile photonic crystals with a complete bandgap at telecom wavelengths

By using direct laser writing into a novel commercially available photoresist and a silicon-double-inversion procedure followed by tempering of the silicon structures, we realize high-quality centered-tetragonal woodpile photonic crystals with complete photonic bandgaps near 1.55 microm wavelength. The 6.9% gap-to-midgap ratio bandgap is evidenced by the comparison of measured transmittance and reflectance spectra with band-structure and scattering-matrix calculations.

Second-harmonic generation from split-ring resonators on a GaAs substrate

We study second-harmonic generation from gold split-ring resonators on a crystalline GaAs substrate. By systematically varying the relative orientation of the split-ring resonators with respect to the incident linear polarization of light and the GaAs crystallographic axes, we unambiguously identify a nonlinear contribution that originates specifically from the interplay of the local fields of the split-ring resonators and the bulk GaAs second-order nonlinear-susceptibility tensor. The experimental results are in good agreement with theoretical modeling.

High frequency of unrecognized hypoglycaemias in patients with Type 2 diabetes is discovered by continuous glucose monitoring

AIMS

To evaluate the use of a CGMS in the detection of hypoglycaemia in people with type 2 diabetes as an outpatient procedure.

METHODS

31 type 2 diabetic patients underwent glucose monitoring by means of CGMS (Medtronic MiniMed) for up to three days. Patients took part in at least four SMBG (self monitoring blood glucose) tests per day. After three days of monitoring, the CGMS data was downloaded and analysed by a physician to identify the frequency of hypoglycaemias (< or =50 mg/dl) and borderline values (51-70 mg/dl), their duration and distribution. Findings were discussed with the patient and if necessary treatment was adjusted. Eight weeks later, monitoring was repeated to asses the effects of the adjusted treatment.

RESULTS

Average duration of sensor wear was 4.19 days. Correlation between the sensor and the SMBG readings was high. A high number of hypoglycaemias and borderline values were detected by the CGMS, most of them unrecognized by the patient. The frequency of hypoglycaemias and borderline values just as the duration could be significantly reduced from first to second monitoring.

CONCLUSION

Using the CGMS in type 2 diabetic patients achieved the detection of numerous hypoglycaemias and borderline values both nocturnal and/or unnoticed. The CGMS provides accurate data, which cannot be achieved by conventional SMBG tests. That opens the possibility for treatment adjustment and improvement in metabolic control. For patients it provides a better understanding of the effects of insulin or oral agents, nutrition and exercises to their glucose level.

Prognostic significance of circulating tumor cells in bone marrow or peripheral blood detected by qualitative and quantitative PCR in pediatric NPM-ALK positive anaplastic large cell lymphoma

9559

Background: Clinical and histopathological characteristics have limited prognostic value for children with anaplastic large cell lymphoma (ALCL). We evaluated the presence, extent and prognostic impact of circulating tumor cells in bone marrow (BM) and peripheral blood (PB) of children and adolescents with NPM-ALK positive ALCL by real-time quantitative PCR for NPM-ALK. Methods: Qualitative and TaqMan-based quantitative PCR assays targeting NPM-ALK were developed with a sensitivity to detect 1 NPM-ALK positive cell among 105 cells. Numbers of NPM-ALK transcripts were normalized to 104 copies ABL (NCN). BM was analyzed from 80 and PB from 52 German patients registered into the subsequent protocols NHL-BFM95 and ALCL99. Results: BM was positive for NPM-ALK in 47.5% of patients, and positivity was significantly correlated with clinical stage, mediastinal or visceral involvement, microscopic BM involvement, and histological subtype, but not with skin or CNS involvement. Qualitative and quantitative PCR results in BM and PB strongly correlated. BM PCR was associated with the cumulative incidence of relapses (CI-R): CI-R was 50±10% for 38 PCR-positive and 15±7% for 42 PCR-negative patients (p10 NCN NPM-ALK in BM had a CI-R of 71±14% compared to a CI-R of 18±6% for 59 patients with =10 NCN (p10 NCN NPM-ALK in BM, clinical risk factors (skin, mediastinal or visceral involvement) and atypical histological subtype, only >10 NCN NPM-ALK remained a significant poor prognostic factor with a risk ratio of 4.74 (1.57–14.3; p<0.006). Conclusions: The detection of NPM-ALK positive cells by PCR in BM is associated with advanced stage disease, visceral involvement and atypical histology. Quantitative PCR in BM or PB allows identification of 20% of patients experiencing 60% of all relapses with an event-free survival of 20%.

No significant financial relationships to disclose.

Identification of two distinct MYC breakpoint clusters and their association with various IGH breakpoint regions in the t(8;14) translocations in sporadic Burkitt-lymphoma

The chromosomal translocation t(8;14) is the hallmark of Burkitt's-lymphoma (BL) and fuses the proto-oncogene c-MYC to the IGH locus. We analyzed the genomic structure of MYC/IGH fusions derived from a large series of 78 patients with t(8;14) and asked (i) whether distinct breakpoint clusters exist within the MYC gene and (ii) whether any pairwise association between particular IGH and MYC breakpoints exist. Identification of such associations will help elucidate the etiology of the breaks on the MYC locus. Scan statistic analyses revealed two distinct, but large clusters within c-MYC containing 60/78 (77%) of the breakpoints. Clusters 1 and 2 were 560 and 779 bp in length within a 4555 bp breakpoint cluster region. Breaks within IGH switch mu and joining region did not differ with respect to their corresponding MYC breakpoints. However, there was a highly significant correlation between breakpoints 5' of MYC cluster 1 and fusions to IGH switch gamma region and breakpoints downstream of MYC cluster 2 and fusions to IGH switch alpha region (chi(2)-test: P<0.005). Chromatin changes governing choice of IGH-Fc region recombination may parallel changes in the MYC gene 5' region chromatin leading to some degree of coordinated ontological specificity in breakpoint location.

[Early surgical management of severe burns]

The success of modern burn therapy is based on an understanding of the pathophysiology and application of burn intensive care implying fluid resuscitation and management of pulmonary or other organ failure. With the development of early eschar excision and wound closure by immediate grafting, survival and cosmetic outcome were further improved. Especially in post-acute therapy, early physical rehabilitation, early reintegration, and early plastic surgical correction of the sequelae are indispensable for the outcome.

Hirudo medicinalis-Anwendungen in der plastischen und rekonstruktiven Mikrochirurgie - eine Literaturübersicht

Medical leech therapy has enjoyed a renaissance in the world of reconstructive microsurgery during recent years. Especially venous congestion is decreased using hirudo medicinalis application such as following replantation of amputated fingers or congested flaps. They provide a temporary relief to venous engorgement whilst venous drainage is re-established. Living in symbiosis with Aeromonas hydrophila, who can digest the sixfold blood meal related to their body weight, and a broad number of anticoagulant agents such as the thrombin inhibitor hirudin, apyrase as well as collagenase, hyaluronidase, Factor Xa inhibitor and fibrinase I and II, leeches decrease venous congestion. Laser Doppler flowmetry could demonstrate a significant increase in superficial skin perfusion following leech application 16 mm around the biting zone. Following the initial blood meal accounting for about 2.5 ml, the anticoagulant effect of the various leeches enzymes follows within the next 5-6 hours, which both account for the beneficial effects. Infection associated with leech therapy is a documented complication of leech application, with reported incidences ranging from 2.4 to 20 % and a chinolone antibiotic is currently recommended to face the potential Aeromonas hydrophila infection. Anemia is a second adverse effect during medicinal leech application which has to be taken account with repetitive blood samples. Besides the successful applications of leeches in various applications in plastic and reconstructive microsurgery, randomized-controlled trials are pending to elucidate the value of hirudo medicinalis according to evidence-based criteria above from case series and case studies.

[Plastic reconstruction of postoncologic defects in the pelvic area]

The surgical management of defects in the pelvic region is a great surgical challenge. Primary tumor recurrences have to be addressed and local infections require appropriate therapy such as rigorous debridement and antibiotic therapy. Plastic surgery provides tissue reconstruction by well perfused flaps and also reestablishment of anatomic structures in the ano-genital region. An early reconstruction also reduces the wound complications of adjuvant or post oncologic therapy and reduces the rate of wound healing problems.

Degradation of the amyloid beta-protein by the novel mitochondrial peptidasome, PreP

Recently we have identified the novel mitochondrial peptidase responsible for degrading presequences and other short unstructured peptides in mitochondria, the presequence peptidase, which we named PreP peptidasome. In the present study we have identified and characterized the human PreP homologue, hPreP, in brain mitochondria, and we show its capacity to degrade the amyloid beta-protein (Abeta). PreP belongs to the pitrilysin oligopeptidase family M16C containing an inverted zinc-binding motif. We show that hPreP is localized to the mitochondrial matrix. In situ immuno-inactivation studies in human brain mitochondria using anti-hPreP antibodies showed complete inhibition of proteolytic activity against Abeta. We have cloned, overexpressed, and purified recombinant hPreP and its mutant with catalytic base Glu(78) in the inverted zinc-binding motif replaced by Gln. In vitro studies using recombinant hPreP and liquid chromatography nanospray tandem mass spectrometry revealed novel cleavage specificities against Abeta-(1-42), Abeta-(1-40), and Abeta Arctic, a protein that causes increased protofibril formation an early onset familial variant of Alzheimer disease. In contrast to insulin degrading enzyme, which is a functional analogue of hPreP, hPreP does not degrade insulin but does degrade insulin B-chain. Molecular modeling of hPreP based on the crystal structure at 2.1 A resolution of AtPreP allowed us to identify Cys(90) and Cys(527) that form disulfide bridges under oxidized conditions and might be involved in redox regulation of the enzyme. Degradation of the mitochondrial Abeta by hPreP may potentially be of importance in the pathology of Alzheimer disease.

[Breast cancer -- plastic surgical strategies for the treatment of tumour infiltration of the thoracic wall and brachial plexus]

Extensive locoregional recurrency or metastatic involvement of brachial plexopathy is a condition that is often associated with advanced systemic breast cancer. In the past the role of surgeon was restricted due to a scepticism as to whether any benefit will be provided for the patient. In the recent 25 years however safe and refined plastic surgical approaches have been developed that provide more options to treat even complex recurrent disease. The strategy of plastic surgery in an interdisciplinary approach of gynecology, oncology and radiotherapy as well as thoracic surgery is outlined.

Efficacy and safety of insulin glulisine in patients with type 1 diabetes

Insulin glulisine (glulisine), a human insulin analogue with a rapid-acting time-action profile, has been developed to fulfil the mealtime (bolus) insulin requirement in patients with diabetes. The aim of this multinational, multi-centre, controlled, open-label, randomized, parallel-group study was to compare the efficacy and safety of insulin glulisine (glulisine) to that of insulin lispro (lispro) in adults diagnosed with Type 1 diabetes. Of the 683 patients randomized, 672 received treatment (339 patients received glulisine, 333 patients received lispro). Over the 26-week study, a similar reduction in mean HbA1c occurred in both groups (adjusted mean change from baseline -0.14% in both groups). The basal insulin dose was relatively unchanged from baseline in the glulisine group but increased in the lispro group (glulisine: 0.12 IU vs. lispro: 1.82 IU; p = 0.0001). As a consequence, total daily insulin dose decreased in the glulisine group but increased in the lispro group (glulisine: -0.86 IU vs. lispro: 1.01 IU; p = 0.0123). There was no relevant difference between the two groups in the reporting of symptomatic hypoglycaemia (overall, nocturnal and severe). This study demonstrates that glulisine provides equivalent glycaemic control to lispro. The clinical relevance of any difference in total daily insulin dose remains to be established.