Regulation of adaptive growth decisions via phosphorylation of the TRAPPII complex in Arabidopsis

Plants often adapt to adverse or stress conditions via differential growth. The trans-Golgi network (TGN) has been implicated in stress responses, but it is not clear in what capacity it mediates adaptive growth decisions. In this study, we assess the role of the TGN in stress responses by exploring the previously identified interactome of the Transport Protein Particle II (TRAPPII) complex required for TGN structure and function. We identified physical and genetic interactions between AtTRAPPII and shaggy-like kinases (GSK3/AtSKs) and provided in vitro and in vivo evidence that the TRAPPII phosphostatus mediates adaptive responses to abiotic cues. AtSKs are multifunctional kinases that integrate a broad range of signals. Similarly, the AtTRAPPII interactome is vast and considerably enriched in signaling components. An AtSK-TRAPPII interaction would integrate all levels of cellular organization and instruct the TGN, a central and highly discriminate cellular hub, as to how to mobilize and allocate resources to optimize growth and survival under limiting or adverse conditions.

Regulation of adaptive growth decisions via phosphorylation of the TRAPPII complex in Arabidopsis

Plants often adapt to adverse or stress conditions via differential growth. The trans-Golgi Network (TGN) has been implicated in stress responses, but it is not clear in what capacity it mediates adaptive growth decisions. In this study, we assess the role of the TGN in stress responses by exploring the interactome of the Transport Protein Particle II (TRAPPII) complex, required for TGN structure and function. We identified physical and genetic interactions between TRAPPII and shaggy-like kinases (GSK3/AtSKs). Kinase assays and pharmacological inhibition provided in vitro and in vivo evidence that AtSKs target the TRAPPII-specific subunit AtTRS120/TRAPPC9. GSK3/AtSK phosphorylation sites in AtTRS120/TRAPPC9 were mutated, and the resulting AtTRS120 phosphovariants subjected to a variety of single and multiple stress conditions in planta . The non-phosphorylatable TRS120 mutant exhibited enhanced adaptation to multiple stress conditions and to osmotic stress whereas the phosphomimetic version was less resilient. Higher order inducible trappii atsk mutants had a synthetically enhanced defect in root gravitropism. Our results suggest that the TRAPPII phosphostatus mediates adaptive responses to abiotic cues. AtSKs are multifunctional kinases that integrate a broad range of signals. Similarly, the TRAPPII interactome is vast and considerably enriched in signaling components. An AtSK-TRAPPII interaction would integrate all levels of cellular organization and instruct the TGN, a central and highly discriminate cellular hub, as to how to mobilize and allocate resources to optimize growth and survival under limiting or adverse conditions.

Correction: A role for brassinosteroid signalling in decision-making processes in the Arabidopsis seedling

[This corrects the article DOI: 10.1371/journal.pgen.1010541.].

A role for brassinosteroid signalling in decision-making processes in the Arabidopsis seedling

Plants often adapt to adverse conditions via differential growth, whereby limited resources are discriminately allocated to optimize the growth of one organ at the expense of another. Little is known about the decision-making processes that underly differential growth. In this study, we developed a screen to identify decision making mutants by deploying two tools that have been used in decision theory: a well-defined yet limited budget, as well as conflict-of-interest scenarios. A forward genetic screen that combined light and water withdrawal was carried out. This identified BRASSINOSTEROID INSENSITIVE 2 (BIN2) alleles as decision mutants with "confused" phenotypes. An assessment of organ and cell length suggested that hypocotyl elongation occurred predominantly via cellular elongation. In contrast, root growth appeared to be regulated by a combination of cell division and cell elongation or exit from the meristem. Gain- or loss- of function bin2 mutants were most severely impaired in their ability to adjust cell geometry in the hypocotyl or cell elongation as a function of distance from the quiescent centre in the root tips. This study describes a novel paradigm for root growth under limiting conditions, which depends not only on hypocotyl-versus-root trade-offs in the allocation of limited resources, but also on an ability to deploy different strategies for root growth in response to multiple stress conditions.

Interactions between Transport Protein Particle (TRAPP) complexes and Rab GTPases in Arabidopsis

Transport Protein Particle II (TRAPPII) is essential for exocytosis, endocytosis, protein sorting and cytokinesis. In spite of a considerable understanding of its biological role, little information is known about Arabidopsis TRAPPII complex topology and molecular function. In this study, independent proteomic approaches initiated with TRAPP components or Rab-A GTPase variants converge on the TRAPPII complex. We show that the Arabidopsis genome encodes the full complement of 13 TRAPPC subunits, including four previously unidentified components. A dimerization model is proposed to account for binary interactions between TRAPPII subunits. Preferential binding to dominant negative (GDP-bound) versus wild-type or constitutively active (GTP-bound) RAB-A2a variants discriminates between TRAPPII and TRAPPIII subunits and shows that Arabidopsis complexes differ from yeast but resemble metazoan TRAPP complexes. Analyzes of Rab-A mutant variants in trappii backgrounds provide genetic evidence that TRAPPII functions upstream of RAB-A2a, allowing us to propose that TRAPPII is likely to behave as a guanine nucleotide exchange factor (GEF) for the RAB-A2a GTPase. GEFs catalyze exchange of GDP for GTP; the GTP-bound, activated, Rab then recruits a diverse local network of Rab effectors to specify membrane identity in subsequent vesicle fusion events. Understanding GEF-Rab interactions will be crucial to unravel the co-ordination of plant membrane traffic.

Nucleon Spin and Momentum Decomposition Using Lattice QCD Simulations

We determine within lattice QCD the nucleon spin carried by valence and sea quarks and gluons. The calculation is performed using an ensemble of gauge configurations with two degenerate light quarks with mass fixed to approximately reproduce the physical pion mass. We find that the total angular momentum carried by the quarks in the nucleon is J_{u+d+s}=0.408(61)_{stat}(48)_{syst} and the gluon contribution is J_{g}=0.133(11)_{stat}(14)_{syst}, giving a total of J_{N}=0.54(6)_{stat}(5)_{syst} that is consistent with the spin sum. For the quark intrinsic spin contribution, we obtain 1/2ΔΣ_{u+d+s}=0.201(17)_{stat}(5)_{syst}. All quantities are given in the modified minimal subtraction scheme at 2 GeV. The quark and gluon momentum fractions are also computed and add up to ⟨x⟩_{u+d+s}+⟨x⟩_{g}=0.804(121)_{stat}(95)_{syst}+0.267(12)_{stat}(10)_{syst}=1.07(12)_{stat}(10)_{syst}, thus satisfying the momentum sum.

Cholecalciferol 20 000 IU Once Weekly in HIV-Positive Patients with Low Vitamin D Levels: Result from a Cohort Study

PURPOSE

To evaluate efficacy and safety of 20 000 IU cholecalciferol weekly in HIV-infected patients.

METHODS

Longitudinal data for 243 HIV-infected patients with paired 25-OH-vitamin D3 values for the same month in 2 consecutive years were stratified by the initiation of supplementation in this retrospective study.

RESULTS

After 1 year of administration of cholecalciferol 20 000 IU weekly, about 78% of patients with initial vitamin D level <20 µg/L achieved vitamin D levels >20 µg/L and 42% achieved levels >30 µg/L. Supplemented patients with baseline vitamin D levels <20 µg/L showed a significant risk reduction for hypocalcemia ( P = .006; risk difference: 20.8%) and a significantly lower increase in alkaline phosphatase (AP) compared to those in the nonsubstituted group.

CONCLUSION

The dose of 20 000 IU of cholecalciferol once weekly was found to be safe and effective. Normalization of vitamin D levels within 1 year was observed in 42% to 75% of the patients.

[Is supplemental ear acupuncture for surgical tooth removal with local anesthesia effective? : A pilot study]

BACKGROUND

The application of ear acupuncture can contribute to a reduction of acute pain. Data on the application of ear acupuncture following oral surgery in odontology is insufficient.

OBJECTIVE

This study investigated the effectiveness of ear acupuncture as an auxiliary analgesic treatment in addition to local anesthesia for operative tooth removal.

METHODS

In this prospective open non-randomized pilot study (in accordance with the CONSORT publication) 2 cohorts of 50 patients each with the indications for an operative tooth removal either with or without the application of ear acupuncture in addition to local anesthesia with articain were observed. Patients were allocated to the groups according to their preference. Pain intensity while resting and while chewing was recorded as the primary parameter for a period of 10 days. The secondary parameters were the subjective experience of anxiety and symptoms, such as headaches, dizziness and nausea.

RESULTS

The two groups did not differ significantly with respect to demographic variables or the use of local anesthetics. At the various measurement intervals, pain intensity while resting or chewing differed significantly between the two groups (ANOVA, p = 0.004, p = 0.007, respectively). Furthermore, the experience of anxiety (ANOVA, p = 0.0001), the number of patients taking analgesics (χ²-test, p = 0.017) and the total postoperative consumption of analgesics (t-test, 0.001) revealed significant differences. In both groups the numerical rating scales (NRS) for postoperative headaches, dizziness and nausea were low.

DISCUSSION AND CONCLUSION

Despite a potential bias and methodological limitations of the study design, the results of this investigation suggest that ear acupuncture influences the experience of pain and anxiety in the postoperative period after tooth removal. As a treatment method with low adverse effects ear acupuncture can contribute to postoperative pain control, especially in patients with preoperative anxiety.

Comparison of in Silico, Electrochemical, in Vitro and in Vivo Metabolism of a Homologous Series of (Radio)fluorinated σ1 Receptor Ligands Designed for Positron Emission Tomography

The imaging of σ₁ receptors in the brain by fluorinated radiotracers will be used for the validation of σ₁ receptors as drug targets as well as for differential diagnosis of diseases in the central nervous system. The biotransformation of four homologous fluorinated PET tracers 1'-benzyl-3-(ω-fluoromethyl to ω-fluorobutyl)-3H-spiro[2]benzofuran-1,4'-piperidine] ([¹⁸ F]1-4) was investigated. In silico studies using fast metabolizer (FAME) software, electrochemical oxidations, in vitro studies with rat liver microsomes, and in vivo metabolism studies after application of the PET tracers [¹⁸ F]1-4 to mice were performed. Combined liquid chromatography and mass spectrometry (HPLC-MS) analysis allowed structural identification of non-radioactive metabolites. Radio-HPLC and radio-TLC provided information about the presence of unchanged parent radiotracers and their radiometabolites. Radiometabolites were not found in the brain after application of [¹⁸ F]2-4, but liver, plasma, and urine samples contained several radiometabolites. Less than 2 % of the injected dose of [¹⁸ F]4 reached the brain, rendering [¹⁸ F]4 less appropriate as a PET tracer than [¹⁸ F]2 and [¹⁸ F]3. Compounds [¹⁸ F]2 and [¹⁸ F]3 possess the most promising properties for imaging of σ₁ receptors in the brain. High σ₁ affinity (K_i =0.59 nm), low lipophilicity (logD_7.4 =2.57), high brain penetration (4.6 % of injected dose after 30 min), and the absence of radiometabolites in the brain favor the fluoroethyl derivative [¹⁸ F]2 slightly over the fluoropropyl derivative [¹⁸ F]3 for human use.

Understanding cancer development processes after HZE-particle exposure: roles of ROS, DNA damage repair and inflammation

During space travel astronauts are exposed to a variety of radiations, including galactic cosmic rays composed of high-energy protons and high-energy charged (HZE) nuclei, and solar particle events containing low- to medium-energy protons. Risks from these exposures include carcinogenesis, central nervous system damage and degenerative tissue effects. Currently, career radiation limits are based on estimates of fatal cancer risks calculated using a model that incorporates human epidemiological data from exposed populations, estimates of relative biological effectiveness and dose-response data from relevant mammalian experimental models. A major goal of space radiation risk assessment is to link mechanistic data from biological studies at NASA Space Radiation Laboratory and other particle accelerators with risk models. Early phenotypes of HZE exposure, such as the induction of reactive oxygen species, DNA damage signaling and inflammation, are sensitive to HZE damage complexity. This review summarizes our current understanding of critical areas within the DNA damage and oxidative stress arena and provides insight into their mechanistic interdependence and their usefulness in accurately modeling cancer and other risks in astronauts exposed to space radiation. Our ultimate goals are to examine potential links and crosstalk between early response modules activated by charged particle exposure, to identify critical areas that require further research and to use these data to reduced uncertainties in modeling cancer risk for astronauts. A clearer understanding of the links between early mechanistic aspects of high-LET response and later surrogate cancer end points could reveal key nodes that can be therapeutically targeted to mitigate the health effects from charged particle exposures.

Molecular imaging of σ receptors: synthesis and evaluation of the potent σ1 selective radioligand [18F]fluspidine

PURPOSE

Neuroimaging of σ(1) receptors in the human brain has been proposed for the investigation of the pathophysiology of neurodegenerative and psychiatric diseases. However, there is a lack of suitable (18)F-labelled PET radioligands for that purpose.

METHODS

The selective σ(1) receptor ligand [(18)F]fluspidine (1'-benzyl-3-(2-[(18)F]fluoroethyl)-3H-spiro[[2]benzofuran-1,4'-piperidine]) was synthesized by nucleophilic (18)F(-) substitution of the tosyl precursor. In vitro receptor binding affinity and selectivity were assessed by radioligand competition in tissue homogenate and autoradiographic approaches. In female CD-1 mice, in vivo properties of [(18)F]fluspidine were evaluated by ex vivo brain section imaging and organ distribution of intravenously administered radiotracer. Target specificity was validated by organ distribution of [(18)F]fluspidine after treatment with 1 mg/kg i.p. of the σ receptor antagonist haloperidol or the emopamil binding protein (EBP) inhibitor tamoxifen. In vitro metabolic stability and in vivo metabolism were investigated by LC-MS(n) and radio-HPLC analysis.

RESULTS

[(18)F]Fluspidine was obtained with a radiochemical yield of 35-45%, a radiochemical purity of ≥ 99.6% and a specific activity of 150-350 GBq/μmol (n = 6) within a total synthesis time of 90-120 min. In vitro, fluspidine bound specifically and with high affinity to σ(1) receptors (K (i) = 0.59 nM). In mice, [(18)F]fluspidine rapidly accumulated in brain with uptake values of 3.9 and 4.7%ID/g and brain to blood ratios of 7 and 13 at 5 and 30 min after intravenous application of the radiotracer, respectively. By ex vivo autoradiography of brain slices, resemblance between binding site occupancy of [(18)F]fluspidine and the expression of σ(1) receptors was shown. The radiotracer uptake in the brain as well as in peripheral σ(1) receptor expressing organs was significantly inhibited by haloperidol but not by tamoxifen. Incubation with rat liver microsomes led to a fast biotransformation of fluspidine. After an incubation period of 30 min only 13% of the parent compound was left. Seven metabolites were identified by HPLC-UV and LC-MS(n) techniques. However, [(18)F]fluspidine showed a higher metabolic stability in vivo. In plasma samples ∼ 94% of parent compound remained at 30 min and ∼ 67% at 60 min post-injection. Only one major radiometabolite was detected. None of the radiometabolites crossed the blood-brain barrier.

CONCLUSION

[(18)F]Fluspidine demonstrated favourable target affinity and specificity as well as metabolic stability both in vitro and in animal experiments. The in vivo properties of [(18)F]fluspidine offer a high potential of this radiotracer for neuroimaging and quantitation of σ(1) receptors in vivo.

Enantioselective σ1 receptor binding and biotransformation of the spirocyclic PET tracer 1'-benzyl-3-(3-fluoropropyl)-3H-spiro[[2]benzofuran-1,4'-piperidine]

It was shown that racemic (±)-2 [1'-benzyl-3-(3-fluoropropyl)-3H-spiro[[2]benzofuran-1,4'-piperidine], WMS-1813] represents a promising positron emission tomography (PET) tracer for the investigation of centrally located σ(1) receptors. To study the pharmacological activity of the enantiomers of 2, a preparative HPLC separation of (R)-2 and (S)-2 was performed. The absolute configuration of the enantiomers was determined by CD-spectroscopy together with theoretical calculations of the CD-spectrum of a model compound. In receptor binding studies with the radioligand [(3)H]-(+)-pentazocine, (S)-2 was thrice more potent than its (R)-configured enantiomer (R)-2. The metabolic degradation of the more potent (S)-enantiomer was considerably slower than the metabolism of (R)-2. The structures of the main metabolites of both enantiomers were elucidated by determination of the exact mass using an Orbitrap-LC-MS system. These experiments showed a stereoselective biotransformation of the enantiomers of 2.

Synthesis, pharmacological activity and structure affinity relationships of spirocyclic σ(1) receptor ligands with a (2-fluoroethyl) residue in 3-position

In order to develop a fluorinated radiotracer for imaging of σ(1) receptors in the central nervous system a series of (2-fluoroethyl) substituted spirocyclic piperidines 3 has been prepared. In the key step of the synthesis 2-bromocinnamaldehyde acetal 5 was added to piperidones 6 with various substituents at the N-atom. Unexpectedly, this reaction led to 2-benzoxepines 8, which were contracted with acid to afford the spirocyclic 2-benzofuranacetaldehydes 9. The best yields were obtained, when the transformations up to the alcohols 10 were performed without isolation of intermediates. Generally the (2-fluoroethyl) derivatives 3 have higher σ(1) affinity and σ(1)/σ(2) selectivity than the corresponding (3-fluoropropyl) derivatives 2. The most promising candidate for the development as radiotracer is the (2-fluoroethyl) derivative 3a (WMS-1828, fluspidine, 1'-benzyl-3-(2-fluoroethyl)-3H-spiro[[2]benzofuran-1,4'-piperidine]), which shows subnanomolar σ(1) affinity (K(i)=0.59nM) and excellent selectivity over the σ(2) subtype (1331-fold) as well as some other receptor systems. The novel synthetic strategy also allows the systematic pharmacological evaluation of intermediate alcohols 10. Despite their high σ(1) affinity (K(i)=6-32nM) and selectivity the alcohols 10 are 10-30-fold less potent than the bioisosteric fluoro derivatives 3.

Pharmacological and metabolic characterisation of the potent σ1 receptor ligand 1′-benzyl-3-methoxy-3H-spiro[[2]benzofuran-1,4′-piperidine]

Objectives

The pharmacology and metabolism of the potent σ1 receptor ligand 1′-benzyl-3-methoxy-3H-spiro[[2]benzofuran-1,4′-piperidine] were evaluated.

Methods

The compound was tested against a wide range of receptors, ion channels and neurotransmitter transporters in radioligand binding assays. Analgesic activity was evaluated using the capsaicin pain model. Metabolism by rat and human liver microsomes was investigated, and the metabolites were identified by a variety of analytical techniques.

Key findings

1′-Benzyl-3-methoxy-3H-spiro[[2]benzofuran-1,4′-piperidine] (compound 1) is a potent σ1 receptor ligand (Ki 1.14 nM) with extraordinarily high σ1/σ2 selectivity (&gt;1100). It was selective for the σ1 receptor over more than 60 other receptors, ion channels and neurotransmitter transporters, and did not interact with the human ether-a-go-go-related gene (hERG) cardiac potassium channel. Compound 1 displayed analgesic activity against neuropathic pain in the capsaicin pain model (53% analgesia at 16 mg/kg), indicating that it is a σ1 receptor antagonist. It was rapidly metabolised by rat liver microsomes. Seven metabolites were unequivocally identified; an N-debenzylated metabolite and a hydroxylated metabolite were the major products. Pooled human liver microsomes formed the same metabolites. Studies with seven recombinant cytochrome P450 isoenzymes revealed that CYP3A4 produced all the metabolites identified. The isoenzyme CYP2D6 was inhibited by 1 (IC50 88 nM) but did not produce any metabolites.

Conclusions

1′-Benzyl-3-methoxy-3H-spiro[[2]benzofuran-1,4′-piperidine] is a potent and selective σ1 receptor antagonist, which is rapidly metabolised. Metabolically more stable σ1 ligands could be achieved by stabilising the N-benzyl substructure.

Lung nodule assessment in computed tomography: precision of attenuation measurement based on computer-aided volumetry

PURPOSE

To compare the reproducibility (r) of CT value measurement of pulmonary nodules using volumetry software (LungCare, LC) and manual ROIs (mROI).

MATERIALS AND METHODS

54 artificial nodules in a chest phantom were scanned three times with CT. CT values were measured with LC and mROI. The intrascan-r was assessed with three measurements in the first scan, and the interscan-r with measurements in three consecutive scans (one observer). Intrascan-r und interobserver-r (two obs.) were assessed in the first scan and in contrast-enhanced CT of 51 nodules from 15 patients (kernels b50f and b80f). Intrascan-r and interscan-r were described as the mean range and interobserver-r as the mean difference of CT values. The significance of differences was tested using t-test and sign test.

RESULTS

Reproducibility was significantly higher for volumetry-based measurements in both artificial and patient nodules (range 0.11 vs. 6.16 HU for intrascan-r, 2.22 vs. 7.03 HU for interscan-r, difference 0.11 vs. 18.42 HU for interobserver-r; patients: 1.78 vs. 13.19 HU (b50f-Kernel) and 1.88 vs. 27.4 HU (b80f-Kernel) for intrascan-r, 3.71 vs. 22.43 HU for interobserver-r). Absolute CT values differed significantly between convolution kernels (pat./mROI: 29.3 [b50f] and 151.9 HU [b80f] pat./LC: 5 [b50f] and 147 HU [b80f]).

CONCLUSION

The reproducibility of volumetry-based measurements of CT values in pulmonary nodules is significantly higher and should therefore be recommended, e. g. in dynamic chest CT protocols. Reproducibility does not depend on absolute CT values.

Evaluation of spirocyclic 3-(3-fluoropropyl)-2-benzofurans as sigma1 receptor ligands for neuroimaging with positron emission tomography

A series of various N-substituted 3-(3-fluoropropyl)-3H-spiro[[2]benzofuran-1,4'-piperidines] (7) has been synthesized. In receptor binding studies, the N-benzyl derivative 7a (WMS-1813) revealed extraordinarily high sigma(1) receptor affinity (K(i) = 1.4 nM) and excellent sigma(1)/sigma(2) selectivity (>600 fold). In vitro biotransformation of 7a with rat liver microsomes led to three main metabolites. N-Debenzylation was inhibited by introduction of an N-phenylethyl residue (7 g). The PET tracer [(18)F]7a was synthesized by nucleophilic substitution of the tosylate 13 with K[(18)F]F-K222-carbonate complex. The decay corrected radiochemical yield of [(18)F]7a was 35-48% with a radiochemical purity of >99.5% and a specific activity of 150-238 GBq/micromol. The radiotracer properties were evaluated in female CD-1 mice by organ distribution and ex vivo brain autoradiography. The radiotracer uptake in the brain was fast and sufficient, with values of approximately 4% injected dose per gram. Target specificity of [(18)F]7a was validated in blocking studies by preapplication of haloperidol, and significant reduction in the uptake of radioactivity was observed in the brain and peripheral organs expressing sigma(1) receptors.

Synthesis of spirocyclic sigma1 receptor ligands as potential PET radiotracers, structure-affinity relationships and in vitro metabolic stability

Several 3H-spiro[[2]benzofuran-1,4'-piperidines] bearing a p-fluorobenzyl residue at the N-atom and various substituents in position 3 of the benzofuran system were synthesized. The crucial reaction steps are the addition of a lithiated benzaldehyde derivative to the p-fluorobenzylpiperidone 5 and the BF(3).OEt(2) catalyzed substitution of the methoxy group of 2a by various nucleophiles. Structure-affinity relationship studies revealed that compounds with two protons (2d), a methoxy group (2a), and a cyano group (2e) in position 3 possess subnanomolar sigma(1) affinity (K(i)=0.18 nM, 0.79 nM, 0.86 nM) and high selectivity against the sigma(2) subtype. The metabolites of 2a, 2d, and 2e, which were formed upon incubation with rat liver microsomes, were identified. Additionally, the rate of metabolic degradation of 2a, 2d, and 2e was determined and compared with the degradation rate of the non-fluorinated spirocyclic compound 1. For the synthesis of the potential PET tracers [(18)F]2a and [(18)F]2e two different radiosynthetic approaches were followed.

Pharmacological and metabolic characterisation of the potent sigma1 receptor ligand 1'-benzyl-3-methoxy-3H-spiro[[2]benzofuran-1,4'-piperidine]

OBJECTIVES

The pharmacology and metabolism of the potent sigma1 receptor ligand 1'-benzyl-3-methoxy-3H-spiro[[2]benzofuran-1,4'-piperidine] were evaluated.

METHODS

The compound was tested against a wide range of receptors, ion channels and neurotransmitter transporters in radioligand binding assays. Analgesic activity was evaluated using the capsaicin pain model. Metabolism by rat and human liver microsomes was investigated, and the metabolites were identified by a variety of analytical techniques.

KEY FINDINGS

1'-benzyl-3-methoxy-3H-spiro[[2]benzofuran-1,4'-piperidine] (compound 1) is a potent sigma1 receptor ligand (Ki 1.14 nM) with extraordinarily high sigma1/sigma2 selectivity (>1100). It was selective for the sigma1 receptor over more than 60 other receptors, ion channels and neurotransmitter transporters, and did not interact with the human ether-a-go-go-related gene (hERG) cardiac potassium channel. Compound 1 displayed analgesic activity against neuropathic pain in the capsaicin pain model (53% analgesia at 16 mg/kg), indicating that it is a sigma1 receptor antagonist. It was rapidly metabolised by rat liver microsomes. Seven metabolites were unequivocally identified; an N-debenzylated metabolite and a hydroxylated metabolite were the major products. Pooled human liver microsomes formed the same metabolites. Studies with seven recombinant cytochrome P450 isoenzymes revealed that CYP3A4 produced all the metabolites identified. The isoenzyme CYP2D6 was inhibited by 1 (IC50 88 nM) but did not produce any metabolites.

CONCLUSIONS

1'-benzyl-3-methoxy-3H-spiro[[2]benzofuran-1,4'-piperidine] is a potent and selective sigma1 receptor antagonist, which is rapidly metabolised. Metabolically more stable sigma1 ligands could be achieved by stabilising the N-benzyl substructure.

[Treatment of oncology patients in the final stadium of disease by prehospital emergency physicians]

BACKGROUND

Presently and even more in the near future more cancer patients will be treated at home especially in the final stage of their disease. For this reason the prehospital emergency system will be confronted with the specific needs of these patients. Palliative care is not part of the German model of post-graduate training regulations for emergency medicine and palliative care teams (PCT) are only involved in the treatment of cancer patients in emergency situations.

METHODS

Over a 12-month period we retrospectively analysed all emergency cases that had been categorised as final cancer stage at 2 emergency sites (one air-based, the other ground-based) involving physicians in an out-of-hospital setting. We analysed all cases for indications of emergency call, prehospital treatment and involvement of a PCT in the treatment of symptoms.

RESULTS

For this period we analysed 2,765 emergency documents and identified more than 2.5% as emergency calls by cancer patients or their relatives (the majority of patients had been in the final stage of the disease). Most emergency calls occurred at times when no general practitioner was on duty and acute dyspnoea (42.7%) was the prominent diagnosis. After emergency treatment 61.8% patients had been admitted to hospital. In most settings a PCT was not involved in the treatment of palliative care patients or their relatives (92.7%).

CONCLUSIONS

Our data demonstrate that care of cancer patients in the final stage of the disease is relevant in emergency medicine. These patients are in need of help based on principles of palliative care. Under these circumstances cooperation of the medical disciplines (emergency and palliative medicine) concerned seems to be necessary. This may increase the possibility for patients to stay at home for the last days of their life. Because of this we are convinced that basic knowledge of palliative care should be integrated into the German model of post-graduate training regulations for emergency care. Combining parts of the curricula (palliative and emergency medicine) it would be possible for emergency physicians to guide their treatment by the ideas and strategies of palliative care. But we are also convinced that the system of PCT should increase and become more involved in prehospital care in emergency cases of palliative care patients.

Nestin expression--a property of multi-lineage progenitor cells?

Tissue-specific progenitor cells are characterized by proliferation and differentiation, but, in contrast to embryonic stem (ES) cells, have limited capacities for self-renewal and no tumourigenic potential. These latter traits make progenitor cells an ideal source for regenerative cell therapies. In this review, we describe what is currently known about nestin, an intermediate filament first identified in neuroepithelial stem cells. During embryogenesis, nestin is expressed in migrating and proliferating cells, whereas in adult tissues, nestin is mainly restricted to areas of regeneration. We show that nestin is abundant in ES-derived progenitor cells that have the potential to develop into neuroectodermal, endodermal and mesodermal lineages. Although it remains unclear what factors regulate in vitro and in vivo expression of nestin, we conclude that nestin represents a characteristic marker of multi-lineage progenitor cells and suggest that its presence in cells may indicate multi-potentiality and regenerative potential.

Long-term oxygen therapy stops the natural decline of endurance in COPD patients with reversible hypercapnia

BACKGROUND

Respiratory muscle weakness is one of the most important causes of hypercapnia in patients with COPD. There is evidence that stable hypercapnic patients will benefit from long-term oxygen therapy (LTOT).

OBJECTIVES

The prognostic role of reversible hypercapnia in COPD is still unclear. Early implementation of LTOT in these patients may influence endurance time and mortality.

METHODS

In this pilot study, we investigated 28 patients (26 males, 49-74 years) with COPD, advanced airflow limitation [forced expiratory volume in 1 s (percentage of predicted value) 40.8 +/- 10.2] and mild hypoxaemia (pO(2) 66.5 +/- 6.3 mm Hg). All patients had developed a moderate reversible hypercapnia during an acute exacerbation or during exercise testing (peak pCO(2) 48.0 +/- 2.5 mm Hg). Patients were allocated randomly to a control group (n = 14) or an LTOT group (n = 14). The two groups were well matched in terms of physiological data. Lung function, endurance time (cycle ergometer), dyspnoea score, blood gases and LTOT compliance were measured at baseline and every 6 months over a period of 3 years.

RESULTS

Endurance time increased from 6.4 +/- 2.7 min at baseline to 7.1 +/- 2.7 min after 1 year in the LTOT group and decreased from 6.1 +/- 3.0 to 4.9 +/- 3.8 min in the controls (p < 0.05). After 1 year, the end-exercise dyspnoea score was significantly lower in the LTOT group (4.5 +/- 1.5) than in the controls (5.7 +/- 1.9).

CONCLUSION

COPD patients with reversible hypercapnia and mild hypoxaemia benefit from LTOT in terms of endurance time and a reduction of exertional dyspnoea after 1 year.

Accumulation of the cell cycle regulators TP53 and CDKN1A (p21) in human fibroblasts after exposure to low- and high-LET radiation

The accumulation of the cell cycle regulators TP53 and CDKN1A (p21/CIP1/WAF1) was investigated after exposure to X rays and carbon ions (170 keV microm(-1)) and xenon, bismuth and uranium ions (8900-15,000 keV microm(-1)) in normal human fibroblasts. The influence of the overall dose and the LET of these radiation types was studied systematically and the kinetics of the cell response was followed up to 24 h after exposure. The accumulation of TP53 protein was dependent on the dose and the LET, and TP53 levels declined to lower levels for all radiation types within 24 h after exposure. CDKN1A levels increased and peaked at 3 to 6 h after exposure. The persisting level of this protein at 24 h was strongly dependent on the dose and the LET for X rays and carbon ions. The exposure to very high-LET ions (8900-15,000 keV microm(-1)) did not lead to a further increase in CDKN1A, suggesting a saturation effect for the induction of this protein. The cellular effects of elevated CDKN1A after particle irradiation are discussed.

Genomic instability in human lymphoid cells exposed to 1 GeV/amu Fe ions

The goal of this study was to assess whether charged particle radiations of importance to spaceflight elicit genomic instability in human TK6 lymphoblasts. The incidence of genomic instability in TK6 cells was assessed ~21 days after exposure to 2, 4, or 6 Fe ions (1 GeV/amu, LET= 146 keV/micrometers). Three indices of instability were used: intraclonal karyotypic heterogeneity, mutation rate analysis at the thymidine kinase (TK1) locus, and re-cloning efficiency. Fifteen of sixty clones demonstrated karyotypic heterogeneity. Five clones had multiple indicators of karyotypic change. One clone was markedly hypomutable and polyploid. Six clones were hypomutable, while 21 clones were mutators. Of these, seven were karyotypically unstable. Six clones had low re-cloning efficiencies, one of which was a mutator. All had normal karyotypes. In summary, many clones that survived exposure to a low fluence of Fe ions manifested one or more forms of genomic instability that may hasten the development of neoplasia through deletion or by recombination.

Mechanisms of mutagenesis in human cells exposed to 55 MeV protons

Protons represent the major type of charged particle radiation in spaceflight environments. The purpose of this study was to assess mutations arising in human lymphoid cells exposed to protons. Mutations were quantitated at the thymidine kinase (TK1) locus in cell lines derived from the same donor: TK6 cells (wt TP53) and WTK1 cells (mutant TP53). WTK1 cells were much more susceptible to mutagenesis following proton exposure than TK6 cells. Intragenic deletions were observed among early-arising TK1 mutants in TK6 cells, but not in WTK1 cells where all of the mutants arose by LOH. Deletion was the predominant mode of LOH in TK6 cells, while allelic recombination was the major mode of LOH in WTK1 cells. Deletions were of variable lengths, from <1 cM to 64 cM, while mutations that arose by allelic recombination often extended to the telomere. In summary, proton exposures elicited many types of mutations at an autosomal locus in human cells. Most involved large scale loss of genetic information, either through deletion or by recombination.

Noninvasive mechanical ventilation improves endurance performance in patients with chronic respiratory failure due to thoracic restriction

OBJECTIVE

Treatment with noninvasive mechanical ventilation (NMV) alleviates hypoventilation and improves gas exchange in patients with chronic respiratory failure (CRF) due to thoracic restriction. However, little is known about the effects of NMV on respiratory and peripheral muscle endurance.

DESIGN

Prospective case-control study.

SUBJECTS

Ten patients in clinically stable condition (age, 53.5 +/- 8.2 years [mean +/- SD]) with mild-to-moderate CRF due to thoracic restriction (PCO(2) between 45 mm Hg and 55 mm Hg) were treated with NMV during the night for 3 months. Ten matched patients (age, 52.2 +/- 9.5 years) receiving 3 months of normal care without NMV served as a control group.

INTERVENTION AND MEASUREMENTS

After a 3-day period of familiarization with the endurance tests, all patients performed a baseline preintervention inspiratory threshold loading test, cycle ergometer test, and shuttle walking test on the same day. The endurance tests were then repeated following the 3-month intervention period.

RESULTS

NMV was used on average for 7.1 +/- 0.9 h/d during the 3-month period. There was a significant improvement in endurance time (p < 0.0001) in all three endurance tests in the NMV group compared with the control group. In the NMV group, endurance time increased by 278 +/- 269% during the inspiratory threshold loading test, by 176 +/- 159% during the cycle ergometer test, and by 32 +/- 22% during the shuttle walking test. Significant improvements (p < 0.01) in both PO(2) and PCO(2) were also observed in the NMV group but not in the control group.

CONCLUSIONS

Three months of treatment with NMV increases both respiratory and peripheral muscle endurance in patients with CRF due to thoracic restriction.

Energy dissipation in photosynthesis: does the quenching of chlorophyll fluorescence originate from antenna complexes of photosystem II or from the reaction center?

Dissipation of light energy was studied in the moss Rhytidiadelphus squarrosus (Hedw.) Warnst., and in leaves of Spinacia oleracea L. and Arabidopsis thaliana (L.) Heynh., using chlorophyll fluorescence as an indicator reaction. Maximum chlorophyll fluorescence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU)-treated spinach leaves, as produced by saturating light and studied between and -20 degrees C, revealed an activation energy delta E of 0.11 eV. As this suggested recombination fluorescence produced by charge recombination between the oxidized primary donor of photosystem II and reduced pheophytin, a mathematical model explaining fluorescence, and based in part on known characteristics of primary electron-transport reactions, was developed. The model permitted analysis of different modes of fluorescence quenching, two localized in the reaction center of photosystem II and one in the light-harvesting system of the antenna complexes. It predicted differences in the relationship between quenching of variable fluorescence Fv and quenching of basal, so-called F0 fluorescence depending on whether quenching originated from antenna complexes or from reaction centers. Such differences were found experimentally, suggesting antenna quenching as the predominant mechanism of dissipation of light energy in the moss Rhytidiadelphus, whereas reaction-center quenching appeared to be important in spinach and Arabidopsis. Both reaction-center and antenna quenching required activation by thylakoid protonation but only antenna quenching depended on or was strongly enhanced by zeaxanthin. De-protonation permitted relaxation of this quenching with half-times below 1 min. More slowly reversible quenching, tentatively identified as so-called qI or photoinhibitory quenching, required protonation but persisted for prolonged times after de-protonation. It appeared to originate in reaction centers.

Ran stimulates spindle assembly by altering microtubule dynamics and the balance of motor activities

The guanosine tri-phosphatase Ran stimulates assembly of microtubule spindles. However, it is not known what aspects of the microtubule cytoskeleton are subject to regulation by Ran in mitosis. Here we show that Ran-GTP stimulates microtubule assembly by increasing the rescue frequency of microtubules three- to eightfold. In addition to changing microtubule dynamics, Ran-GTP also alters the balance of motor activities, partly as a result of an increase in the amount of motile Eg5, a plus-end-directed microtubule motor that is essential for spindle formation. Thus, Ran regulates multiple processes that are involved in spindle assembly.

Different mechanisms of radiation-induced loss of heterozygosity in two human lymphoid cell lines from a single donor

Allelic loss is an important mutational mechanism in human carcinogenesis. Loss of heterozygosity (LOH) at an autosomal locus is one outcome of the repair of DNA double-strand breaks (DSBs) and can occur by deletion or by mitotic recombination. We report that mitotic recombination between homologous chromosomes occurred in human lymphoid cells exposed to densely ionizing radiation. We used cells derived from the same donor that express either normal TP53 (TK6 cells) or homozygous mutant TP53 (WTK1 cells) to assess the influence of TP53 on radiation-induced mutagenesis. Expression of mutant TP53 (Met 237 Ile) was associated with a small increase in mutation frequencies at the hemizygous HPRT (hypoxanthine phosphoribosyl transferase) locus, but the mutation spectra were unaffected at this locus. In contrast, WTK1 cells (mutant TP53) were 30-fold more susceptible than TK6 cells (wild-type TP53) to radiation-induced mutagenesis at the TK1 (thymidine kinase) locus. Gene dosage analysis combined with microsatellite marker analysis showed that the increase in TK1 mutagenesis in WTK1 cells could be attributed, in part, to mitotic recombination. The microsatellite marker analysis over a 64-cM region on chromosome 17q indicated that the recombinational events could initiate at different positions between the TK1 locus and the centromere. Virtually all of the recombinational LOH events extended beyond the TK1 locus to the most telomeric marker. In general, longer LOH tracts were observed in mutants from WTK1 cells than in mutants from TK6 cells. Taken together, the results demonstrate that the incidence of radi-ation-induced mutations is dependent on the genetic background of the cell at risk, on the locus examined, and on the mechanisms for mutation available at the locus of interest.