Rational design of highly stabilized and selective adrenomedullin analogs

The peptide hormone adrenomedullin (ADM) consists of 52 amino acids with a disulfide bond and an amidated C-terminus. Due to the vasodilatory and cardioprotective effects, the agonistic activity of the peptide on the adrenomedullin 1 receptor (AM1 R) is of high pharmacological interest. However, the wild-type peptide shows low metabolic stability leading to rapid degradation in the cardiovascular system. Previous work by our group has identified proteolytic cleavage sites and demonstrated stabilization of ADM by lipidation, cyclization, and N-methylation. Nevertheless, these ADM analogs showed reduced activity and subtype selectivity toward the closely related calcitonin gene-related peptide receptor (CGRPR). Here, we report on the rational development of ADM derivatives with increased proteolytic stability and high receptor selectivity. Stabilizing motifs, including lactamization and lipidation, were evaluated regarding AM1 R and CGRPR activation. Furthermore, the central DKDK motif of the peptide was replaced by oligoethylene glycol linkers. The modified peptides were synthesized by Fmoc/t-Bu solid-phase peptide synthesis and receptor activation of AM1 R and CGRPR was measured by cAMP reporter gene assay. Peptide stability was tested in human blood plasma and porcine liver homogenate and analyzed by RP-HPLC and MALDI-ToF mass spectrometry. Combination of the favorable lactam, lipidation, ethylene glycol linker, and previously described disulfide mimetic resulted in highly stabilized analogs with a plasma half-life of more than 144 h. The compounds display excellent AM1 R activity and wild-type-like selectivity toward CGRPR. Additionally, dose-dependent vasodilatory effects of the ADM derivatives lasted for several hours in rodents. Thus, we successfully developed an ADM analog with long-term in vivo activity.

Pinpointing the interaction site between semaphorin-3A and its inhibitory peptide

Semaphorin-3A (Sema-3A) is a chemorepellant protein with various biological functions, including kidney development. It interacts with a protein complex consisting of the receptors neuropilin-1 (NRP-1) and plexin-A1. After acute kidney injury, Sema-3A is overexpressed and secreted, leading to a loss of kidney function. The development of peptide inhibitors is a promising approach to modulate the interaction of Sema-3A with its receptor NRP-1. Few interaction points between these binding partners are known. However, an immunoglobulin-like domain-derived peptide of Sema-3A has shown a positive effect on cell proliferation. To specify these interactions between the peptide inhibitor and the Sema-3A-NRP-1 system, the peptides were modified with the photoactivatable amino acids 4-benzoyl-l-phenylalanine or photo-l-leucine by solid-phase peptide synthesis. Activity was tested by an enzyme-linked immunosorbent-based binding assay, and crosslinking experiments were analyzed by Western blot and mass spectrometry, demonstrating a specific binding site of the peptide at Sema-3A. The observed signals for Sema-3A-peptide interaction were found in a defined area of the Sema domain, which was also demonstrated to be involved in NRP-1 binding. The presented data identified the interaction site for further development of therapeutic peptides to treat acute kidney injury by blocking the Sema-3A-NRP-1 interaction.

Potent Inhibition of HIF1α and p300 Interaction by a Constrained Peptide Derived from CITED2

Disrupting the interaction between HIF1α and p300 is a promising strategy to modulate the hypoxia response of tumor cells. Herein, we designed a constrained peptide inhibitor derived from the CITED2/p300 complex to disturb the HIF1α/p300 interaction. Through truncation/mutation screening and a terminal aspartic acid-stabilized strategy, a constrained peptide was constructed with outstanding biochemical/biophysical properties, especially in binding affinity, cell penetration, and serum stability. To date, our study was the first one to showcase that stabilized peptides derived from CITED2 using helix-stabilizing methods acted as a promising candidate for modulating hypoxia-inducible signaling.

MO053INHIBITION OF SODIUM PHOSPHATE TRANSPORTER NPT2A IMPROVES EXPERIMENTAL VASCULAR CALCIFICATION AND PHOSPHATE HOMEOSTASIS IN RATS

Background and Aims

A dysregulated phosphate homeostasis is strongly associated with mortality, cardiovascular events and vascular calcification, particularly in patients suffering from CKD. Inhibition of the tubular phosphate transporter Npt2a provides a novel and unique mechanism to address phosphate homeostasis imbalance and vascular calcification.

Method

Npt2a activity was measured in a cell-based assay, using a stable CHO cell line with inducible Npt2a expression. Male Wistar rats were used for all experiments. Healthy rats were treated orally with BAY 767, a potent Npt2a inhibitor developed at Bayer AG to assess urinary phosphate excretion. Vascular calcification was induced by administration of a pan-FGFR inh. (25mg/kg) for 10 days. Calcium content in the aorta was measured as surrogate for vascular calcification. Blood samples were withdrawn at the end of the study to determine the plasma levels of FGF-23, parathyroid hormone and phosphate with commercially available assay systems according to the manufactures protocols (FGF-23 and PTH: ELISA Kit, Immuntopics; phosphate: Pentra400 system).

Results

BAY 767 was identified as potent Npt2a inhibitor, with an IC50 of 2.9/6 nM on rat/ human Npt2a, respectively, selective over Npt2b, Npt2c and Pit-1. Single dose treatments of healthy rats resulted in a significant, dose-dependent increase in urinary phosphate excretion within 16h. In an experimental vascular calcification model, massive vascular calcification and hyperphosphatemia was induced by daily oral administration of a FGFR inh. Simultaneous treatment with the Npt2a inhibitor BAY 767 significantly inhibited vascular calcification in comparison to untreated rats. In this set-up the plasma phosphate level was increased after 10 days up to 3.7 mmol/L in the FGFR inh. treated group compared to 1.9 mmol/L in control animals, whilst treatment with BAY 767 reduced plasma levels to 2.7 mmol/L. In addition, FGF-23 and PTH were also reduced under compound BAY 767 treatment. However, in the same model 2.2% lanthanum carbonate was not beneficial with respect to vascular calcification.

Conclusion

Our results show for the first time that treatment with a Npt2a inhibitor improves vascular calcification by addressing urinary phosphate excretion and phosphate homeostasis in rats.

Npt2a inhibition may provide a new therapeutic principle for patients suffering from disbalanced phosphate homeostasis and vascular calcifications, including CKD patients.

A Selective Carborane-Functionalized Gastrin-Releasing Peptide Receptor Agonist as Boron Delivery Agent for Boron Neutron Capture Therapy

Boron neutron capture therapy (BNCT) allows the selective elimination of malignant tumor cells without affecting healthy tissue. Although this binary radiotherapy approach has been known for decades, BNCT failed to reach the daily clinics to date. One of the reasons is the lack of selective boron delivery agents. Using boron loaded peptide conjugates, which address G protein-coupled receptors overexpressed on tumor cells allow the intracellular accumulation of boron. The gastrin-releasing peptide receptor (GRPR) is a well-known target in cancer diagnosis and can potentially be used for BNCT. Here, we present the successful introduction of multiple bis-deoxygalactosyl-carborane building blocks to the GRPR-selective ligand [d-Phe⁶, β-Ala¹¹, Ala¹³, Nle¹⁴]Bn(6-14) (sBB2L) generating peptide conjugates with up to 80 boron atoms per molecule. Receptor activation was retained, metabolic stability was increased, and uptake into PC3 cells was proven without showing any intrinsic cytotoxicity. Furthermore, undesired uptake into liver cells was suppressed by using l-deoxygalactosyl modified carborane building blocks. Due to its high boron loading and excellent GRPR selectivity, this conjugate can be considered as a promising boron delivery agent for BNCT.

Tuning a modular system - synthesis and characterisation of a boron-rich s-triazine-based carboxylic acid and amine bearing a galactopyranosyl moiety

Introduction of a bis(isopropylidene)-protected galactopyranosyl moiety in s-triazine-based boron-rich carboxylic acids and amines results in soluble and suitable coupling partners for tumour-selective biomolecules with applications as selective agents for boron neutron capture therapy (BNCT). Bearing either a carboxylic acid or primary amine as a functional group, these compounds are highly versatile and thus largely extend the possible coupling strategies with suitable biomolecules. Modification of the gastrin-releasing peptide receptor (GRPR) selective agonist [d-Phe⁶, β-Ala¹¹, Ala¹³, Nle¹⁴]Bn(6-14) with the carboxylic acid derivative yielded a bioconjugate with an optimal receptor activation and internalisation profile. This demonstrates the great potential of this approach for the development of novel boron delivery agents.

Selective Neuropeptide Y Conjugates with Maximized Carborane Loading as Promising Boron Delivery Agents for Boron Neutron Capture Therapy

G-protein-coupled receptors like the human Y₁ receptor (hY₁R) are promising targets in cancer therapy due to their high overexpression on cancer cells and their ability to internalize together with the bound ligand. This mechanism was exploited to shuttle boron atoms into cancer cells for the application of boron neutron capture therapy (BNCT), a noninvasive approach to eliminate cancer cells. A maximized number of carboranes was introduced to the hY₁R-preferring ligand [F⁷,P³⁴]-NPY by solid phase peptide synthesis. Branched conjugates loaded with up to 80 boron atoms per peptide molecule exhibited a maintained receptor activation profile, and the selective uptake into hY₁R-expressing cells was demonstrated by internalization studies. In order to ensure appropriate solubility in aqueous solution, we proved the need for eight hydroxyl groups per carborane. Thus, we suggest the utilization of bis-deoxygalactosyl-carborane building blocks in solid phase peptide synthesis to produce selective boron delivery agents for BNCT.

Enlargement of a Modular System-Synthesis and Characterization of an s-Triazine-Based Carboxylic Acid Ester Bearing a Galactopyranosyl Moiety and an Enormous Boron Load

The amount of boron accumulated in tumor tissue plays an important role regarding the success of the boron neutron capture therapy (BNCT). In this article, we report a modular system, combining readily available starting materials, like glycine, 1,3,5-triazine and the well-known 9-mercapto-1,7-dicarba-closo-dodecaborane(12), as well as α-d-galactopyranose for increased hydrophilicity, with a novel boron-rich tris-meta-carboranyl thiol.

Modular triazine-based carborane-containing carboxylic acids - synthesis and characterisation of potential boron neutron capture therapy agents made of readily accessible building blocks

Based on a modular combination of s-triazine, the well-known 9-mercapto-1,7-dicarba-closo-dodecaborane(12) and commercially available carboxylic acids, namely thioglycolic acid, glycine, and N_α-Boc-l-lysine, several carboxylic acid derivatives were synthesised and fully characterised. The thioglycolic acid derivative was introduced into a peptide hormone by solid phase peptide synthesis. High activity and selective internalisation into peptide receptor-expressing cells was observed. With a very high boron content of twenty boron atoms, these derivatives are interesting as selective Boron Neutron Capture Therapy (BNCT) agents.

Non-reducible disulfide bond replacement implies that disulfide exchange is not required for hepcidin-ferroportin interaction

Previous studies have led to opposing hypotheses about the requirement of intermolecular disulfide exchange in the binding of the iron regulatory peptide hepcidin to its receptor ferroportin. To clarify this issue, we used the diaminodiacid approach to replace the disulfide bonds in hepcidin with non-reducible thioether bonds. Our results implied that disulfide exchange is not required for the interaction between hepcidin and ferroportin. This theory is further supported by our development of biologically active minihepcidins that do not show activity dependence on cysteine.

A stable meta-carborane enables the generation of boron-rich peptide agonists targeting the ghrelin receptor

Boron neutron capture therapy (BNCT) is a binary cancer therapy, which combines the biochemical targeting of a boron-containing drug with the regional localization of radiation treatment. Although the concept of BNCT has been known for decades, the selective delivery of boron into tumor cells remains challenging. G protein-coupled receptors that are overexpressed on cancer cells in combination with peptidic ligands can be potentially used as shuttle system for a tumor-directed boron uptake. In this study, we present the generation of short, boron-rich peptide conjugates that target the ghrelin receptor. Expression of the ghrelin receptor on various cancer cells makes it a viable target for BNCT. We designed a novel hexapeptide super-agonist that was modified with different specifically synthesized carborane monoclusters and tested for ghrelin receptor activation. A meta-carborane building block with a mercaptoacetic acid linker was found to be optimal for peptide modification, owing to its chemical stability and a suitable activation efficacy of the conjugate. The versatility of this carborane for the development of peptidic boron delivery agents was further demonstrated by the generation of highly potent, boron-loaded conjugates using the backbone of the known ghrelin receptor ligands growth hormone releasing peptide 6 and Ipamorelin.

Adrenomedullin 2.0: Adjusting Key Levers for Metabolic Stability

The 52 amino acid peptide hormone adrenomedullin (ADM) plays a major role in the development and regulation of the cardiovascular and lymphatic system and has therefore gained significant interest for clinical applications. Because adrenomedullin exhibits low metabolic stability, enhancement of the plasma half-life is essential for peptide-based drug design. Fluorescently labeled ADM analogues synthesized by Fmoc/t-Bu solid phase peptide synthesis were used to analyze their enzymatic degradation and specific fragmentation pattern in human blood plasma. The determination of important cleavage sites allowed the development of selectively modified peptides in a rational approach. By combination of palmitoylation, lactam-bridging, and Nα-methylation, ADM analogues protected from enzymatic cleavage in human blood were developed and revealed an explicitly elongated half-life of 5 days in comparison to the wild-type in vitro. This triple-modification did not alter the selectivity of the analogues at the AM1 receptor, highlighting their potential for therapeutic applications.

Cutaneous norepinephrine application in complex regional pain syndrome

Patients with complex regional pain syndrome (CRPS) (n=20) were examined in order to evaluate cutaneous reactions to norepinephrine (NE) on both the affected and the unaffected limb in comparison to healthy controls. Sixteen female and four male patients suffering from very acute and therefore untreated CRPS with a mean duration of 5.5 weeks were included in this study. Two groups of healthy volunteers served as control groups: the first group (n=18) according to the same study protocol as CRPS patients, and the second group (n=10) after warming up one limb. Norepinephrine was iontophoresized (0.2 mA, 120 s) and vasoconstriction was recorded by laser-doppler flowmetry. Pain sensations were simultaneously rated on a visual analogue scale (VAS). Five patients underwent a second trial with higher intracutaneous NE concentrations in order to study possible dose-dependent effects of NE on pain sensation. After acclimatization, skin temperature was recorded by infra-red thermography. The NE-induced reduction of skin blood flow was significantly higher in the affected limb in the patient group (33.0 vs 11.2%, p<0.005). None of the patients reported pain or hyperalgesia. The skin temperature of CRPS patients was significantly higher in the affected limb (34.7 vs 32.5 degrees C, p<0.001). The first control group did not show any difference between left and right sides concerning NE-induced vasoconstriction or skin temperature. The second control group had an increased unilateral skin temperature after warming up (35.0 vs 34.3 degrees C, p<0.006) and demonstrated a significantly increased vasoconstriction on the warmer side (52.0 vs 20.2%, p<0.03) corresponding to findings in patients with acute CRPS. The present study proves that there are signs of decreased sympathetic activity in the affected limb in very acute CRPS. However, no indication was found for increased sensitivity of vascular alpha-receptors in the very acute stages of CRPS, and there was also no indication for a significant direct contribution of the sympathetic nervous system to pain in very acute CRPS.

Mechanical properties of polypropylene structural foams with fiber-reinforced skins

This article reports on the effect of skin thickness, core density, and skin composition on the mechanical properties of sandwich structural foams. In this study, the skin layers are polypropylene reinforced by different amounts of hemp fibers while the core is the same polypropylene foamed using different amounts of chemical blowing agent. The sandwich structures are characterized mechanically in terms of tensile and flexural properties. The results show that fiber introduction in the skins not only improved the mechanical properties, but also produced finer cell structures in the core. Finally, a mechanical model including fiber concentration, skin thickness, and density profile in the core is proposed to predict with high accuracy the elastic modulus of the sandwich foams.

Comparative study of lignins isolated from Alfa grass (Stipa tenacissima L.)

Soda lignin, dioxane lignin and milled lignin were isolated from Alfa grass (Stipatenacissima L.). The physico-chemical characterization of three different lignins: one industrial lignin precipitated from soda spent liquor and two lignin preparations isolated under laboratory conditions from Alfa grass (also know as Esparto grass) was performed. The structures of lignins were studied by three non-destructive (FT-IR, solid state (13)C NMR and UV/visible spectroscopy) and two destructive (nitrobenzene oxidation and thermogravimetric analysis) methods. Elemental analysis and the methoxyl content determination were performed in order to determine the C(9) formulae for the studied lignins. The total antioxidant capacity of the studied lignins has been determined and compared to commercial antioxidants commonly used in thermoplastic industry.

Compression Moulding of Polypropylene Foams and Their Properties

Compression moulding was used to produce polypropylene foams using azodicarbonamide as a chemical blowing agent. The morphology of the foams is reported in terms of cell size, cell density, and skin thickness using 1.5, 2, 2.5 and 3% of blowing agent. The resulting foams were characterized mechanically in terms of tensile and flexural moduli and comparison with mechanical models was made to predict foam performance. In general, mechanical properties, cell density, skin thickness and foam density decreased, while cell size increased with increasing amount of blowing agent. It was also found that simple mechanical models based solely on foam density and skin thickness were not able to correctly predict all the experimental data. For better prediction, foam density profile must be used.

The novel alpha7 nicotinic acetylcholine receptor agonist N-[(3R)-1-azabicyclo[2.2.2]oct-3-yl]-7-[2-(methoxy)phenyl]-1-benzofuran-2-carboxamide improves working and recognition memory in rodents

The relative contribution of alpha4beta2, alpha7 and other nicotinic acetylcholine receptor (nAChR) subtypes to the memory enhancing versus the addictive effects of nicotine is the subject of ongoing debate. In the present study, we characterized the pharmacological and behavioral properties of the alpha7 nAChR agonist N-[(3R)-1-azabicyclo[2.2.2]oct-3-yl]-7-[2-(methoxy)phenyl]-1-benzofuran-2-carboxamide (ABBF). ABBF bound to alpha7 nAChR in rat brain membranes (Ki=62 nM) and to recombinant human 5-hydroxytryptamine (5-HT)3 receptors (Ki=60 nM). ABBF was a potent agonist at the recombinant rat and human alpha7 nAChR expressed in Xenopus oocytes, but it did not show agonist activity at other nAChR subtypes. ABBF acted as an antagonist of the 5-HT3 receptor and alpha3beta4, alpha4beta2, and muscle nAChRs (at higher concentrations). ABBF improved social recognition memory in rats (0.3-1 mg/kg p.o.). This improvement was blocked by intracerebroventricular administration of the alpha7 nAChR antagonist methyllycaconitine at 10 microg, indicating that it is mediated by alpha7 nAChR agonism. In addition, ABBF improved working memory of aged rats in a water maze repeated acquisition paradigm (1 mg/kg p.o.) and object recognition memory in mice (0.3-1 mg/kg p.o.). Rats trained to discriminate nicotine (0.4 mg/kg s.c.) from vehicle did not generalize to ABBF (0.3-30 mg/kg p.o.), suggesting that the nicotine cue is not mediated by the alpha7 nAChR and that selective alpha7 nAChR agonists may not share the abuse liability of nicotine. Our results support the hypothesis that alpha7 nAChR agonists may provide a novel therapeutic strategy for the treatment of cognitive deficits with low abuse potential.

[Diabetic coma and hypoglycemia in children. What to do when in an emergency]

With a few very rare exceptions, hypoglycemia and diabetic coma almost always occur in patients with diabetes mellitus, and are among the most common emergencies in children. For the emergency physician, it is important, on the basis of a specific history-taking and information from, for example, family members, supplemented by a clinical examination done in the light of knowledge of the typical symptoms of each of the entities, to determine whether hypoglycemia or diabetic coma is presenting. The most important technical examination is the measurement of blood glucose. In the event of hypoglycemia, the first therapeutic measure is the administration of sugar--in the case of a comatose patient via a venous line. The s.c. or i.m. administration of glucagon to achieve short-term improvement might be considered. In the event of a diabetic coma, abundant electrolyte solution is initially needed, followed by i.v. insulin. Referral to hospital is mandatory.

BAY 43-9006 Exhibits Broad Spectrum Oral Antitumor Activity and Targets the RAF/MEK/ERK Pathway and Receptor Tyrosine Kinases Involved in Tumor Progression and Angiogenesis

The RAS/RAF signaling pathway is an important mediator of tumor cell proliferation and angiogenesis. The novel bi-aryl urea BAY 43-9006 is a potent inhibitor of Raf-1, a member of the RAF/MEK/ERK signaling pathway. Additional characterization showed that BAY 43-9006 suppresses both wild-type and V599E mutant BRAF activity in vitro. In addition, BAY 43-9006 demonstrated significant activity against several receptor tyrosine kinases involved in neovascularization and tumor progression, including vascular endothelial growth factor receptor (VEGFR)-2, VEGFR-3, platelet-derived growth factor receptor beta, Flt-3, and c-KIT. In cellular mechanistic assays, BAY 43-9006 demonstrated inhibition of the mitogen-activated protein kinase pathway in colon, pancreatic, and breast tumor cell lines expressing mutant KRAS or wild-type or mutant BRAF, whereas non-small-cell lung cancer cell lines expressing mutant KRAS were insensitive to inhibition of the mitogen-activated protein kinase pathway by BAY 43-9006. Potent inhibition of VEGFR-2, platelet-derived growth factor receptor beta, and VEGFR-3 cellular receptor autophosphorylation was also observed for BAY 43-9006. Once daily oral dosing of BAY 43-9006 demonstrated broad-spectrum antitumor activity in colon, breast, and non-small-cell lung cancer xenograft models. Immunohistochemistry demonstrated a close association between inhibition of tumor growth and inhibition of the extracellular signal-regulated kinases (ERKs) 1/2 phosphorylation in two of three xenograft models examined, consistent with inhibition of the RAF/MEK/ERK pathway in some but not all models. Additional analyses of microvessel density and microvessel area in the same tumor sections using antimurine CD31 antibodies demonstrated significant inhibition of neovascularization in all three of the xenograft models. These data demonstrate that BAY 43-9006 is a novel dual action RAF kinase and VEGFR inhibitor that targets tumor cell proliferation and tumor angiogenesis.

Omega-carboxypyridyl substituted ureas as Raf kinase inhibitors

Bis-aryl ureas have been disclosed previously as a potent class of Raf kinase inhibitors. Modifications in the amide portion led to an improvement in aqueous solubility, an important characteristic for an oral drug. Based on this finding, we hypothesize that this portion of the molecule is directed towards the solvent in Raf-1.

Design and discovery of small molecules targeting raf-1 kinase

Raf kinase, an enzyme which acts downstream in the Ras signaling pathway, is involved in cancerous cell proliferation. Thus, small molecule inhibitors of Raf kinase activity may be important agents for the treatment of cancer. A novel class of Raf-1 inhibitors was discovered, using a combination of medicinal and combinatorial chemistry approaches. This effort culminated in the identification of the clinical candidate BAY 43-9006, currently undergoing Phase I clinical trials. The present review summarizes the medicinal chemistry development of ureas as highly potent inhibitors of Raf-1 kinase.

Chest sonography in the diagnosis of pulmonary embolism: a comparison with MRI angiography and ventilation perfusion scintigraphy

AIM

To compare the diagnostic performance of chest sonography, MRI angiography and ventilation/perfusion intigraphy in pulmonary embolism (PE).

METHOD

In a prospective clinical study, 55 patients (41 women, 14 men, age 23 - 91 years) with clinical signs of PE were investigated within 48 hours of the onset of symptoms. The final diagnosis was made by MRI angiography (reference method).

RESULTS

PE was diagnosed in a total of 36 patients. Chest sonography revealed rounded or wedge-shaped hypoechoic lesions in 30 patients. On ventilation/perfusion (V/P) scintigraphy, 41 patients had positive V/P scans, but only 23 were of high probability. Chest ultrasound had a positive predictive value of 97 % to diagnose PE. The sensitivity, specificity, the negative predictive value and accuracy were 81 %, 84 %, 84 % and 82 %, respectively. As 18 patients had inconclusive scans, the diagnostic performance of ventilation/perfusion scintigraphy was poor. The positive predictive value, sensitivity and specificity were 58 %, 42 % and 91 %, respectively. Patients in whom PE was excluded mainly suffered from congestive heart failure, bronchopulmonary infections or pulmonary hypertension.

CONCLUSION

A negative sonographic study cannot rule out PE with certainty. However, a chest sonography is of acceptable diagnostic value in patients with suspected PE and may be used as an adjunct or guide to more established methods.

Straightforward syntheses of furanomycin derivatives and their biological evaluation

Several types of furanomycin analogues were synthesized and investigated with respect to their antibacterial activity. Two different synthetic pathways were developed, based on aldol reactions/ring closing metathesis and an ester enolate Claisen rearrangement. Only the natural product and its desmethyl derivative showed antibacterial activity, pointing towards a narrow structure-activity relationship.

Features of gastritis predisposing to gastric adenoma and early gastric cancer

BACKGROUND/AIMS

Helicobacter pylori gastritis is a risk factor for the development of gastric cancer. The results of several studies indicate that gastric adenomas, which are considered premalignant lesions, may also be associated with H pylori gastritis. However, it is not clear whether there are different patterns of gastritis in these patients compared with patients with gastric cancer or patients with H pylori gastritis alone. Therefore, this study was designed to investigate the patterns of gastritis in these three groups of patients.

METHODS

The histological features of gastric mucosa at a distance from the tumour were analysed prospectively in 118 patients with gastric adenoma (mean age, 71.8; female to male ratio, 6 : 4). In addition, for every patient with H pylori associated gastric adenoma an age and sex matched control patient with either H pylori associated early gastric cancer of the intestinal type or H pylori gastritis only was investigated.

RESULTS

Only 60 patients (50.9%) with gastric adenoma were infected with H pylori. In the remaining patients, complete atrophic gastritis predominated. In those patients with adenoma and H pylori infection, the gastritis was similar to that seen in patients with early gastric cancer (median score, 2 for activity and degree of gastritis in the antrum and corpus); intestinal metaplasia was common to both groups. These two groups differed significantly from patients with H pylori gastritis only (median grade and activity of gastritis, 1 in antrum and corpus), in whom intestinal metaplasia was rare.

CONCLUSIONS

It appears that gastric adenomas and gastric intestinal cancer arise by analogous mechanisms. However, owing to severe atrophic gastritis and a lower incidence of H pylori, adenomas do not appear to be definite precursor lesions for gastric cancer.

Autonomic failure after stroke--is it indicative for pathophysiology of complex regional pain syndrome?

In order to find pieces of evidence for a central origin of autonomic failure in complex regional pain syndrome I (CRPS I), the pattern of autonomic symptoms in CRPS I patients was compared to patients a few days after stroke. Autonomic failure in the latter group is assumed to represent definite CNS origin. Seventeen stroke patients, 21 patients in the acute and late stage of CRPS I and a control group of 23 healthy subjects were investigated. Detailed neurological examination was performed, sweating was induced centrally (thermoregulatory sweating, TST) and peripherally by carbachol iontophoresis (QSART) and quantified by evaporation hygrometry. Skin temperature was assessed by infrared thermography. The incidence of motor-sensory dysfunction (without pain) and the incidence of edema was strikingly similar in stroke and CRPS patients. Furthermore, stroke patients had increased TST but not QSART responses on the contralesional limb (P < 0.05) and skin temperature was decreased (P < 0.001). The same pattern of autonomic failure was found in late CRPS (TST: P < 0.02, skin temperature: P < 0.01) whereas in acute CRPS additional, presumably peripheral mechanisms, contribute to sympathetic symptoms. In conclusion, our investigation suggests that many clinical symptoms and the main features of sympathetic dysfunction in CRPS could be explained by a CNS pathophysiology.

Discovery of a new class of p38 kinase inhibitors

The MAP kinase p38 has been implicated in cytokine signaling, and its inhibitors are potentially useful for the treatment of arthritis and osteoporosis. Novel small-molecule inhibitors of p38 kinase were derived from a combinatorial chemistry effort and exhibit activity in the nanomolar range. Very steep structure-activity relationships are observed within this class.

1-Phenyl-5-pyrazolyl ureas: potent and selective p38 kinase inhibitors

Inhibitors of the MAP kinase p38 are potentially useful for the treatment of arthritis and osteoporosis. Several 2,3-dichlorophenyl ureas were identified as small-molecule inhibitors of p38 by a combinatorial chemistry effort. Optimization for cellular potency led to the discovery of a new class of potent and selective p38 kinase inhibitors, exemplified by the 1-phenyl-5-pyrazolyl urea 7 (IC50 = 13 nM).

Experimental tissue acidosis leads to increased pain in complex regional pain syndrome (CRPS)

The aim of this study was to investigate the role of local acidosis in the generation of pain in complex regional pain syndrome (CRPS). We investigated ten patients with CRPS of the upper extremity with a mean duration of the disease of 43 weeks (range 4-280 weeks) and ten control subjects for sensitivity to infusion of fluids with low pH (pH 6.1). Another group of five CRPS patients and three healthy controls was investigated using the same protocol but neutral infusion fluid (pH 7.4). A motorized syringe pump was installed for a constant infusion of synthetic interstitial fluid (SIF, either acidified (pH 6.1) or neutral) into the skin at the back of the hands and, thereafter, into the interosseus I muscle on both sides. A flow rate of 30 ml/h was chosen for intradermal and 7.5 ml/h for intramuscular infusion over a period of 10 min. The magnitude of pain was rated on an electronic visual analogue scale. Patients were requested to give their ratings every 10 s during the whole stimulation period. The ratings were normalized as fractions of individual grand mean values. We found significantly increased pain perception during infusion of acidified SIF on the affected side in CRPS patients. Low pH fluid into the skin was significantly more painful between 4 and 6 min (ipsi 1.27 normalized rating (NR) (0. 19-1.94), contra 0.31 NR (0.03-0.51), P<0.02) and between 8 and 10 min (ipsi 1.38 NR (0.19-1.94), contra 0.08 NR (0-0.27), P<0.03) on the affected side, while analysis over the whole stimulation period just failed to reach statistical significance (ipsi 281 area under the curve (AUC) (187-834), contra 87 AUC (28-293), P=0.059). Low pH infusion into the muscle was significantly more painful on the affected side during the whole infusion time (ipsi 861 AUC (308-1377), contra 190 AUC (96-528), P<0.01). The quality of the deep pain during infusion into the muscle was described by the patients as very similar to the CRPS-related pain. In controls we found no side differences of pain intensity during low pH stimulation. Neutral SIF evoked no pain at all, neither in CRPS patients (ipsi 0 AUC, contra 0 AUC) nor in healthy controls. Our results suggest that hyperalgesia to protons is present in patients with CRPS. Further, we could demonstrate that pain is not only restricted to the skin but is also generated in deep somatic tissue of the affected limb.