Endotoxin-induced acute renal failure in rats: effects of L-arginine and nitric oxide synthase inhibition on renal function

BACKGROUND

The regulation of renal hemodynamics is closely related to the L-arginine (L-Arg)/nitric oxide (NO) pathway. NO - metabolized from L-Arg - is capable of improving renal function in ischemic and toxic acute renal failure (ARF), while NO synthase (NOS) inhibition induces deterioration in renal function. The mortality rate in patients with septic shock is increased when treated with a non-selective NOS inhibitor, while the incidence of ARF requiring renal replacement therapy is unaffected. To date, there are no studies on the impact of NOS substrate (L-Arg) and inhibitor (L-NMMA) on renal function in early lipopolysaccharide (LPS)-induced ARF.

METHODS

ARF was induced by intravenous (i.v.) LPS. Animals were treated with L-Arg, L-NMMA (NOS substrate and inhibitor), a combination of both or saline. Glomerular filtration rate (GFR), urine flow, fractional sodium excretion, excretion of NO metabolism stable end products and blood pressure (BP) were recorded at baseline, after ARF induction, during drug infusion and thereafter.

RESULTS

L-Arg induced better GFR during infusion. Excretion of the NO metabolism end products was highest in the L-Arg group and lowest in the NOS inhibitor group. L-Arg administration had no influence on BP, while L-NMMA induced a slight elevation.

CONCLUSIONS

We conclude that exogenous L-Arg exerts beneficial effects in early LPS-induced ARF in rats during drug infusion, while NOS inhibition has no influence on GFR. Subcellular compartmentalization of the L-Arg pool in cytoplasma and the rapid utilization of exogenous L-Arg in such a micro-environment could explain this effect, which has been observed in other ARF models and was called the "L-Arg paradox". In further studies the effects of early and prolonged administration of L-Arg in endotoxinemia should be investigated.

Metal concentrations in soil and seepage water due to infiltration of roof runoff by long term numerical modelling

The qualitative effects of stormwater infiltration on soil and seepage water are investigated with long term numerical modelling. The retention behaviour of different soils and materials used in infiltration devices is determined with batch and column tests. Results of the laboratory tests are adsorption isotherms which represent input data for numerical transport modelling. The long term simulations are performed with combinations of different solutions (types of roof runoff) and infiltration devices (swale and trench) under different hydrogeological conditions. The presented results contain the infiltration of low polluted roof runoff, runoff from a roof with zinc sheets and from a roof with copper sheets concerning the heavy metals zinc, copper and lead. The increase of concentrations in the infiltration body is high. For the infiltrated water, the results show a migration to groundwater only for the low adsorbing soil.

[Tissue engineering: new treatment of cartilage alterations in degenerative joint diseases in horses--preliminary results of a long term study]

Degenerative alterations in fetlock joints of the forelimb are common diagnoses for horses. The hyaline cartilage has a low capacity to regenerate and the treatment by veterinarians is often insufficient. As a final result, horses with articular cartilage defects are often not able to take part in competitions anymore. To establish an autologous cartilage repair method, we set artificial lesions (8 mm in diameter) into the fetlock joints of the forelimb of three horses. These defects were closed with autologous chondrocyte implants, which were fixed with titan-suture-anchors. After 3, 12 and 24 months, biopsies were taken by arthroscopy. One horse was euthanized after 9, another one after 24 months. The repair tissue was examined histologically and by biochemical analysis of hydroxyproline and glycosaminoglycan, which are typical cartilage related substances. After 9 months, the integration of the implant into native cartilage was demonstrated by electron microscopy. After 24 months, histological staining showed a similar morphology of the cartilage repair tissue compared with the surrounding native cartilage. Biochemical analysis of typical cartilage matrix molecules revealed formation of hyaline-like cartilage within tissue engineered autologous chondrocyte transplants.

Imatinib: a selective tyrosine kinase inhibitor

The understanding of the pathophysiology of a large number of cancer types provides a strategy to target cancer cells with minimal effect on normal cells. Protein phosphorylation and dephosphorylation play a pivotal role in intracellular signaling; to regulate signal transduction pathways, there are approximately 700 protein kinases and 100 protein phosphatases encoded within the human genome. In cancer, as well as in other proliferative diseases, unregulated cell proliferation, differentiation and survival frequently results from abnormal protein phosphorylation. Although it is often possible to identify a single kinase that plays a pivotal role in a given disease, the development of drugs based upon protein kinase inhibition has been hampered by unacceptable side effects resulting from a lack of target selectivity. With the growing understanding of the molecular biology of protein tyrosine kinases and the use of structural information, the design of potential drugs directed towards the bind adenosine triphosphate (ATP)-binding site of a single target has become possible. These advances have transferred emphasis away from the identification of potent kinase inhibitors and more towards issues of target selectivity, cellular efficacy, therapeutic effectiveness and tolerability. In this paper, the relationship between molecular biology and drug discovery methods, as utilized for the identification of anticancer drugs, will be illustrated.

Release of algesic substances in human experimental muscle pain

OBJECTIVE

We employed the 'delayed onset of muscle soreness' (DOMS) and the 'hypertonic saline' muscle pain models in combination with muscle microdialysis to evaluate the role of potentially algesic substances (lactate, glutamate, prostaglandin E2 (PGE2), nitric oxide (NO) and substance P (SP)) in the development of human muscle pain.

METHODS

DOMS was induced by 2 sets of 50 concentric/eccentric contractions of the calf muscles 24 h before the start of microdialysis. During microdialysis pain was stimulated through calf muscle contractions (dorsal and plantar flexions of the foot). Hypertonic saline was injected into the biceps muscle (5 x 200 microl 5.8% NaCl, 2 min interval) during dialysis. The calf (no treatment) and biceps (normal saline) of the other side was used as control.

RESULTS

Both models reliably induced muscle pain with similar intensities as assessed by visual analog scale. The DOMS exercise caused an increase of lactate in serum and the calf muscles of the DOMS leg. In addition, glutamate, PGE2 and substance P dialysate concentrations increased following contraction-induced pain stimulation (peak concentrations 125 +/- 20 microM, 239 +/- 45 pg/ml and 60 +/- 11 pg/ml for glutamate, PGE2 and SP, respectively). This increase did not occur in the control leg (peak concentrations 97 +/- 12 microM, 114 +/- 26 pg/ml and 46 +/- 9 pg/ml for glutamate, PGE2 and SP, respectively). Concentrations of nitric oxide were lower in the DOMS than control leg, particularly during the first 4h of microdialysis. Injection of hypertonic saline into the biceps muscle caused a significant increase of dialysate glutamate concentrations (peak 50 +/- 3 microM) whereas glutamate remained constant after injection of normal saline (mean 26 +/- 1 microM). Injection of hypertonic saline had no effect on lactate, PGE2 or NO levels.

CONCLUSION

Our data support the notion that an inflammatory reaction may be involved in muscle soreness following eccentric exercise, whereas the injection of hypertonic saline into the muscle probably directly stimulates muscle nociceptors and causes glutamate release.

Strong self-phase modulation in planar chalcogenide glass waveguides

Single-mode planar waveguides were fabricated from chalcogenide glass compounds with large Kerr nonlinearities. Strong self-phase modulation of subpicosecond pulses along with low linear and nonlinear absorption losses demonstrates the potential for ultrafast, low-power, all-optical processing applications.

Tyrosine kinase inhibitors: from rational design to clinical trials

Protein kinases play a crucial role in signal transduction as well as in cellular proliferation, differentiation, and various regulatory mechanisms. The inhibition of growth related kinases, especially tyrosine kinases, might provide new therapies for diseases such as cancer. The progress made in the crystallization of protein kinases has confirmed that the ATP-binding domain of tyrosine kinases is an attractive target for drug design. Three successful examples of drug design at Novartis using a tyrosine kinase as a molecular target are described. PKI166, a pyrrolo[2,3,-d]pyrimidine derivative, is a dual inhibitor of both the EGFR and the ErbB2 kinases. The compound entered clinical trials in 1999, based on its favorable preclinical profile: potent inhibition of EGF-mediated signalling in cells, in vivo antitumor activity in several EGFR overexpressing xenograft tumor models in nude mice, long-lasting inhibition of EGF-stimulated EGFR autophosphorylation in tumor tissue, good oral bioavailability in animals, and no prohibitive in vitro and in vivo toxicity findings. The anilino-phthalazine derivative PTK787/ZK222584 (Phase I, co-developed by Schering AG, Berlin) is a potent and selective inhibitor of both the KDR and Flt-1 kinases with interesting anti-angiogenic and pharmacokinetic properties (orally bioavailable). STI571 (Glivec, Gleevec), a phenylamino-pyrimidine derivative, is a potent inhibitor of the Abl tyrosine kinase, which is present in 95% of patients with chronic myelogenous leukemia (CML). The compound specifically inhibits proliferation of v-Abl and Bcr-Abl expressing cells (including cells from CML patients) and shows anti-tumor activity as a single agent in animal models at well-tolerated doses. Pharmacologically relevant concentrations are achieved in the plasma of animals (oral administration). Promising data from phase I and II clinical trials in CML patients (98% haematological response rate in Phase I) support the fact that the STI571 represents a new treatment modality for CML. In addition, potent inhibition of the PDGFR and c-Kit tyrosine kinases also indicates its possible clinical use in solid tumors.

High-throughput evaluation of olefin copolymer composition by means of attenuated total reflection Fourier tranform infrared spectroscopy

As a consequence of developing fully automated reactors for organic and organometallic synthesis and polymerizations combined with rapid on-line analysis, databases, and data mining, the analysis of polymers with respect to composition and properties has been speeded up. High-throughput evaluation of olefin copolymers requires fast measurements and high accuracy without tedious sample preparation such as pressing KBr pellets. This has been achieved by using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR spectroscopy) in conjunction with multivariate calibration in order to determine the composition of olefin copolymers such as ethene/propene, ethene/1-hexene and ethene/1-octene copolymers.

DNA polynucleotide probes generated from representatives of the genus Acinetobacter and their application in fluorescence in situ hybridization of environmental samples

The application of rRNA directed polynucleotide probes carrying multiple labels facilitates the detection of target cells by fluorescence in situ hybridizations and allows specific enrichment by cell fishing. So far, exclusively RNA transcript probes have been used. To reduce the effort in the preparation of the polynucleotides and to enhance their stability, DNA probes matching a part of the highly variable domain III on the 23S rRNA were constructed by amplification of the target region using PCR. Fluorescent labeling was achieved by incorporation of Cy3-labeled desoxyribonucleotides in the amplification. DNA polynucleotide probes were constructed for the seven validly described Acinetobacter species. Amplified domain III rDNA of A. baumannii and A. calcoaceticus could be readily applied as species specific probe. In addition, rDNA fragments could be used to recognize two groups of species, one comprising A. haemolyticus, A. junii and A. radioresistens and the other one A. lwoffii and A. johnsonii. Acinetobacter baumannii cells, some of them occurring in filaments, could be detected by in situ hybridization in native samples of activated sludge.

A new structural class of selective and non-covalent inhibitors of the chymotrypsin-like activity of the 20S proteasome

We describe the identification and in vitro characterization of a series of 2-aminobenzylstatine derivatives that inhibit non-covalently the chymotrypsin-like activity of the 20S proteasome. Our initial SAR data demonstrate that the 2-aminobenzylstatine core structure can effectively serve as the basis for designing potent, selective and non-covalent inhibitors of the chymotrypsin-like activity of the 20S proteasome.

Modeling of the binding mode of a non-covalent inhibitor of the 20S proteasome. Application to structure-based analogue design

The 2-aminobenzvlstatine derivative I is a 20S proteasome inhibitor of a novel chemical type identified by high throughput screening. The compound specifically inhibits the chymotrypsin-like catalytic activity of the human proteasome with an IC50 value in the micromolar range. Using the crystal structure of the yeast proteasome, we modeled the structure of the human proteasome in complex with 1. As one of the first applications of the model in our oncology programme targeting the proteasome, we designed an analogue of the inhibitor having enhanced stacking/hydrophobic interactions with the enzyme. One order of magnitude in inhibitory potency was gained.

Methylammonium groups at the solid walls of nanometer-sized, water-filled monolayer gaps as binding sites for a tetraanionic porphyrin

Long-chain hydrosulfides containing two secondary amide functions and either electron-poor or electron-rich carbon-carbon double bonds were self-assembled on gold surfaces around a flat-lying, octaanionic porphyrin. Rigid and reactive surface monolayers with 2 nm-wide, porphyrin-based gaps were thus obtained. The gold electrodes were then immersed in water, and the double bonds on the gaps' surfaces reacted with methylamine. It was added to the double bonds either by Michael addition or by bromination with hypobromite followed by methylamine substitution. Only the double bonds at the border of the gaps were accessible to methylamine dissolved in the bulk water volume and could react. The walls of the rigid membrane gaps now contained methylammonium groups at the sites of the double bonds in defined heights. A tetracationic copper(II) porphyrinate could not diffuse any more into the gap and did not quench the fluorescence of the octaanionic porphyrin on the bottom of the gap. A tetraanionic porphyrin, on the other hand, was fixated by the ring of ammonium groups. The bound porphyrin then acted as molecular cover for the gap with respect to ferricyanide transport from bulk water to the electrode. It was removed by raising the pH to a value of 12, where the methylammonium groups were neutralized to amines. Lowering the pH to 7 again and addition of more of the anionic porphyrin reclosed the gap.The porphyrin "cover" should be localized at distances of 8-10 and 20 A from the bottom porphyrin by multiple charge interactions. The 8-10 A distance is ideal for studies of photoinduced electron transfer between two porphyrin monomers of different redox potential. Furthermore it was found, that redox-active tyrosine could be trapped in the water volume above the porphyrin on gold.

Proteasome- and p38-dependent regulation of ERK3 expression

Proteasome inhibition leads to accumulation of transcription factors, heat shock proteins, cyclins, and other proteasome substrate proteins by blocking their proteolytic degradation. An increase in gene transcription upon proteasome inhibition was found for a group of proteins, including p21(WAF1/CIP1), ubiquitin, and transcription factors. In this study, we have demonstrated selective up-regulation of extracellular signal-regulated kinase 3 (ERK3) mRNA and protein expression upon treatment with peptide-based proteasome inhibitors or lactacystin. ERK3 is a family member of the mitogen-activated protein kinases (also called ERK) that are key mediators of signal transduction from the cell surface to the nucleus. ERK3 up-regulation is independent of the p53, Bcl2, and caspase 3 status of cells. p38 pathway kinase inhibitors prevent proteasome-dependent ERK3 induction and enhance the antiproliferative effect of proteasome inhibitors. MCF-7 cells expressing ERK3 ectopically show increased resistance toward proteasome inhibition. The results indicate that ERK3 expression is a consequence of p38 pathway activation and most probably represents an intracellular defense or rescue mechanism against cell stress and damage induced by proteasome inhibition.

Local field enhancement effects for nanostructuring of surfaces

We report on a method that allows the nanostructuring of surfaces with intense laser pulses. For this purpose isolated polystyrene spheres with diameters in the order of the laser wavelength were deposited on a silicon or glass surface. Illumination with short and ultrashort laser pulses produced holes underneath these particles. Calculations of the field near the particles make clear that geometrical optics, that is, focusing by a spherical lens, as well as near-field effects, contribute to the size and shape of these holes. This technique can be utilized for the parallel structuring of large surface areas with a single laser shot.

[Chances in surgical treatment of bronchial carcinoma under palliative conditions]

Palliative surgery aims at symptomatic relief in patients in whom curative therapy seems not feasible. When diagnostic imaging techniques describe advanced stage IIIa, IIIb or IV malignancy, despite of palliative intention curative resection may still be possible. Objective of the present study was to investigate lung cancer patients undergoing surgery with palliative intent and to compare their prognosis with patients whose tumor resection had been complete (R0) or incomplete (R1/R2).

PATIENTS AND METHOD

Patients were assigned to one of the three groups on the basis of the following criteria: palliative intention with subsequent complete resection (group I, n = 11); curative intention with subsequent incomplete resection (group II, n = 38), palliative intention with incomplete resection (group III, n = 23). Additionally 3 patients were operated on by explorative thoracotomy. A total number of 75 patients was therefore investigated. Median follow-up period was 34.5 months. Survival rates were calculated using the Kaplan-Meier method.

RESULTS

The following procedures involving resection of pulmonary tissue were performed: pneumonectomy (n = 10), extended pneumonectomy (n = 32), lobectomy (n = 5), extended lobectomy (n = 11), sleeve lobectomy (n = 7), bilobectomy (n = 3), extended bilobectomy (n = 4). The 30 days hospital mortality rate was 13%. Median survival times were 25.5 months in group I, 12.8 months in group II and 7.7 months in group III (statistical significance: group I vs. group II/III, p < 0.05).

CONCLUSIONS

Results of the present study show that patients with bronchial carcinoma in advanced tumor stages III and IV may still benefit from pulmonary resection, particularly when reduction of their somatic complaints is considered. In 11 patients, R0 resection was feasible leading to a statistically significant prolongation of their survival rates.