Messung und Berechnung der CD-Spektren der Biaryl-Alkaloide Ancistrocladein und Dioncophyllein A [1] / Detection and Calculation of the CD Spectra from the Biaryl Alkaloids Ancistrocladeine and Dioncophylleine A [1]

The circular dichroism (CD) of the biaryls ancistrocladeine and dioncophylleine A has been studied. The CNDO/S method in combination with a Boltzmann weighting o f different structures using AM 1 energies has been applied to reproduce the experimental CD spectra o f the two alkaloids with known absolute configuration at with those o f the exciton chirality method.

A Lys-Trp cation-π interaction mediates the dimerization and function of the chloride intracellular channel protein 1 transmembrane domain

Chloride intracellular channel protein 1 (CLIC1) is a dual-state protein that can exist either as a soluble monomer or in an integral membrane form. The oligomerization of the transmembrane domain (TMD) remains speculative despite it being implicated in pore formation. The extent to which electrostatic and van der Waals interactions drive folding and association of the dimorphic TMD is unknown and is complicated by the requirement of interactions favorable in both aqueous and membrane environments. Here we report a putative Lys37-Trp35 cation-π interaction and show that it stabilizes the dimeric form of the CLIC1 TMD in membranes. A synthetic 30-mer peptide comprising a K37M TMD mutant was examined in 2,2,2-trifluoroethanol, sodium dodecyl sulfate micelles, and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine liposomes using far-ultraviolet (UV) circular dichroism, fluorescence, and UV absorbance spectroscopy. Our data suggest that Lys37 is not implicated in the folding, stability, or membrane insertion of the TMD peptide. However, removal of this residue impairs the formation of dimers and higher-order oligomers. This is accompanied by a 30-fold loss of chloride influx activity, suggesting that dimerization modulates the rate of chloride conductance. We propose that, within membranes, individual TMD helices associate via a Lys37-mediated cation-π interaction to form active dimers. The latter findings are also supported by results of modeling a putative TMD dimer conformation in which Lys37 and Trp35 form cation-π pairs at the dimer interface. Dimeric helix bundles may then associate to form fully active ion channels. Thus, within a membrane-like environment, aromatic interactions involving a polar lysine side chain provide a thermodynamic driving force for helix-helix association.

NI-1: a novel canine mastocytoma model for studying drug resistance and IgER-dependent mast cell activation

BACKGROUND

Advanced mast cell (MC) disorders are characterized by uncontrolled growth of neoplastic MC in various organs, mediator-related symptoms, and a poor prognosis. Kit mutations supposedly contribute to abnormal growth and drug resistance in these patients.

METHODS

We established a novel canine mastocytoma cell line, NI-1, from a patient suffering from MC leukemia.

RESULTS

NI-1 cells were found to form mastocytoma lesions in NOD/SCID IL-2Rgamma(null) mice and to harbor several homozygous Kit mutations, including missense mutations at nucleotides 107(C→T) and 1187(A→G), a 12-bp duplication (nucleotide 1263), and a 12-bp deletion (nucleotide 1550). NI-1 cells expressed several MC differentiation antigens, including tryptase, Kit, and a functional IgE receptor. Compared to the C2 mastocytoma cell line harboring a Kit exon 11 mutation, NI-1 cells were found to be less responsive against the Kit tyrosine kinase inhibitors (TKI) masitinib and imatinib, but were even more sensitive against proliferation-inhibitory effects of the mammalian target of rapamycin (mTOR) blocker RAD001 and PI3-kinase/mTOR blocker NVP-BEZ235. The Kit-targeting multikinase inhibitors PKC412 and dasatinib were also found to override TKI resistance in NI-1 cells, and produced growth inhibition with reasonable IC(50) values (<0.1 μM).

CONCLUSION

NI-1 may serve as a useful tool to investigate IgE-dependent reactions and mechanisms of abnormal growth and drug resistance in neoplastic MC in advanced mastocytosis.

Visualization of fine-scale genomic structure by oligonucleotide-based high-resolution FISH

The discovery of complex structural variations that exist within individual genomes has prompted a need to visualize chromosomes at a higher resolution than previously possible. To address this concern, we established a robust, high-resolution fluorescence in situ hybridization (FISH) method that utilizes probes derived from high complexity libraries of long oligonucleotides (>150 mers) synthesized in massively parallel reactions. In silico selected oligonucleotides, targeted to only the most informative elements in 18 genomic regions of interest, eliminated the need for suppressive hybridization reagents. Because of the inherent flexibility in our probe design methods, we readily visualized regions as small as 6.7 kb with high specificity on human metaphase chromosomes, resulting in an overall success rate of 94%. Two-color FISH over a 479-kb duplication, initially reported as being identical in 2 individuals, revealed distinct 2-color patterns representing direct and inverted duplicons, demonstrating that visualization by high-resolution FISH provides further insight in the fine-scale complexity of genomic structures. The ability to design FISH probes for any sequenced genome along with the ease, reproducibility, and high level of accuracy of this technique suggests that it will be powerful for routine analysis of previously difficult genomic regions and structures.

The effect of bisphosphonates and titanium particles on osteoblasts

In an attempt to increase the life of cementless prostheses, an hydroxyapatite-coated implant which releases a bisphosphonate has been suggested as a drug-delivery system. Our in vitro study was designed to determine the maximum dose to which osteoblasts could be safely exposed.

Our findings demonstrated that zoledronate did not impair the proliferation of human osteoblasts when used at concentrations below 1 μm. Murine cells can be exposed to concentrations as high as 10 μm.

A concentration of 0.01% of titanium particles did not impair the proliferation of either cell line. Zoledronate affected the alkaline phosphatase activity of murine osteoblasts through a chelation phenomenon. The presence of titanium particles strongly decreased the alkaline phosphatase activity of murine osteoblasts. We did not detect any synergic effect of zoledronate and titanium particles on the behaviour of both human and murine osteoblasts.

Calcium phosphate drug delivery system: influence of local zoledronate release on bone implant osteointegration

Despite total hip replacement (THR) gives generally satisfactory results, the quality of outcome in young patients is markedly decreased compared to the average THR outcome. For this population, pharmacological treatment with bisphosphonate would be beneficial to decrease the peri-implant osteolysis. However, as this population does not necessarily suffer from osteoporosis, a nonsystemic treatment would be preferable. Zoledronate was then grafted to hydroxyapatite (HA) coating of titanium implants. The implants were inserted in rat condyles with various zoledronate concentrations. A positive concentration-dependent effect was observed on the peri-implant bone density and on different histomorphometric parameters. Importantly for the outcome of the implants, the mechanical fixation was increased by the local presence of zoledronate. The obtained results open the way of an easy transformation of currently existing HA-coated implants by grafting bisphosphonate onto the coating in order to increase their service life in the patients.

Peri-implant Bone Remodeling after Total Hip Replacement Combined with Systemic Alendronate Treatment: A Finite Element Analysis

In order to decrease the peri-implant bone loss during the life-time of the implant, oral use of anti-osteoporosis drugs (like bisphosphonates) has been suggested. In this study, bone remodeling parameters identified from clinical trials of alendronate were used to simulate the effect of those drugs used after total hip arthroplasty on the peri-implant bone density. Results of the simulation show that the oral administrated drugs increase bone density around the implant and decreases, at the same time, the micromovements between the implant and the surrounding bone tissue. Incorporation of drug effect in numerical studies of bone remodeling is a promising tool especially to predetermine safe bisphosphonate doses that could be used with orthopedic implants.

The psychological effects of exposure to mixed organic solvents on car painters

PURPOSE

Interest in diseases of the nervous system resulting from occupational exposure to mixed organic solvents has greatly increased. The aim of our study was to identify preclinical effects of low-level chronic solvent exposure on the central nervous system in car painters by assessing their cognitive performance.

METHODS

This psychological study involved 169 clinically healthy male volunteers (84 car painters and 85 controls) and is part of a comprehensive study investigating effects of solvent exposure. The test battery included paper-pencil tests (vocabulary test, block design test, c.i., d2 test), computer-based tests (digit span test, simple-choice reaction time test), and a questionnaire to assess the participants' mental state.

RESULTS

Car painters with long-term exposure to solvents showed psychological deviations such as deficits in concentration, memory and reaction time compared to unexposed subjects. The significant differences between the two groups were confirmed by multivariate statistical analysis.

CONCLUSIONS

Our study displayed psychological effects associated with long-term solvent exposure in concentrations below German threshold limit values. These findings emphasize the necessity to promote the resolute compliance with occupational safety and health regulations in affected companies.

Hospitalization vs. outpatient care in the management of triplet gestations

OBJECTIVE

To compare the course and outcome of triplet gestations under a preventive care strategy that includes hospitalization, surveillance, bed rest, and daily specialized care from the beginning of the second trimester, with pregnancies managed according to the Croatian standard outpatient care protocol for multiplets.

METHODS

A retrospective study of 79 triplet pregnancies. Preventive hospitalization from the beginning of the second trimester, with complete bed rest and all necessary interventions, was chosen by 55 women (Group I). The remaining 24 women (Group II) elected the standard outpatient protocol for multiple pregnancies. Outpatient management with prophylactic bed rest was initiated at home as soon as the multiple pregnancy was diagnosed. After 28 weeks of gestation, all outpatients were hospitalized until delivery irrespective of symptoms.

RESULTS

There was no difference between the groups regarding maternal age, race, pre-pregnancy weight and height, weight gain during the first 24 weeks of pregnancy, or the proportion of pregnancies achieved with assisted reproductive technology. Four out of 55 women (7.2%) from Group I and 4 out of 24 women (12.5%) from Group II had monochorionic triplet pregnancies (P=n.s.). Nulliparity was more frequent in Group I than in Group II (P=0.006). Elective cesarean delivery was significantly more frequent in Group I (46 out of 55 gestations, 72.7%) than in Group II (9 out of 24 gestations, 37.5%), P=0.024. Gestational age at delivery and mean birth weight were significantly higher in Group I than in Group II (P<0.001). Deliveries up to 28 weeks of pregnancy were infrequent in Group I (P=0.02). Thirty-three gestations in Group I (60%) and 6 (25%) in Group II had a duration of 33-36 weeks (P<0.001). Two out of 55 triplet gestations in Group I (3.6%) and 4 out of 24 in Group II (16.7%) ended in spontaneous abortion (P=0.053). The survival of the three triplets was more frequent in Group I than in Group II (P=0.048). For gestations reaching 24 weeks or more, the fetal and perinatal death rate was significantly lower in Group I (P<0.001). In Group I the intrauterine death rate for fetuses weighing 1500 g or less was also significantly lower (P=0.007), and the early neonatal death rate was almost half (15.8 vs. 28.9%, P=0.157). There were no differences in other pregnancy complications between the two groups except significantly more frequent preterm premature rupture of membranes and preterm labor requiring parenteral tocolysis in Group II (P=0.042 and 0.036, respectively), and significantly more frequent fetal growth retardation in Group I (P<0.001).

CONCLUSION

Preventive hospitalization offers a better outcome for triplets even though prolonged hospitalization and all other procedures necessary to achieve optimal pregnancy outcome are also offered in the Croatian standard outpatient care protocol for multiplet pregnancies.

Expression and dimerization of the rat activin subunits betaC and betaE: evidence for the ormation of novel activin dimers

Activins are cytokines of the transforming growth factor beta family, which plays a central role in the determination of cell fate and the regulation of tissue balance. Family members are composed of two subunits and this dimerization is critical for liganding their cognate receptors and execution of proper functions. In the current study we focused on the localization of activin betaA, betaB, betaC and betaE subunits in the adult rat and analyzed the composition of putative activin beta dimers. By dissecting tissue distribution of various activins, we found that the liver, in particular the hepatocytes, is the major source for activin betaC and betaE transcripts, since other tissues almost failed to express these isoforms. In sharp contrast, the emergence of activin betaA and betaB appeared ubiquitous. Using a highly selective proteome approach, we were able to identify homo- as well as heterodimers of individual activin subunits, indicating a high redundancy of ligand composition. Certainly, this broad potential to homo- and heterodimerize has to be considered in future studies on activin function.

[Microbiological and clinical effects of selective bowel decontamination in transthoracic resection of carcinoma of the esophagus and cardia]

INTRODUCTION

Surgical therapy of carcinoma of the esophagus or cardia by transthoracic esophageal resection is associated with a high morbidity in which nosocomial infections have a great importance. This study investigates the influence of prophylactic selective bowel decontamination on the course and results of transthoracic resection of the esophagus.

METHODS

Seventy patients with carcinoma of the esophagus and cardia were included in this prospective and partially randomized study at the University of Heidelberg. Twenty-five patients received prophylactically selective bowel decontamination with tobramycin, polymyxin B and amphotericin B. The treatment course was documented uniformly. In addition, microbiological screening was performed by swab examinations of nose, throat and anus, by urine and blood cultures, and the documentation of results of additional microbiological diagnostic studies.

RESULTS

Bacteriological screening confirmed a reduction in infectious agents and a change of their spectrum in the respiratory and digestive tract without an increase in multiresistant bacteria. Patients who received selective bowel decontamination had a lower infection rate, a shorter artificial respiration period and a shorter intensive care stay without statistically significant differences. The mortality rate was 4% vs 9% in the control group (95% confidence interval -0.172-0.116).

CONCLUSION

This study confirms the feasibility and microbiological effectiveness of selective bowel decontamination in the context of surgical therapy which is associated with a high nosocomial infection rate. The result of the clinical treatment seems slightly more favorable in the treatment group. Decisive are complications caused by surgery which fundamentally determine the clinical course and frequently cause infectious complications. The prophylactic use of selective bowel decontamination may be useful in patients with an increased risk of prolonged ventilation support or colon interposition but it is not to be generally recommended.

Comparative gene expression profiles following UV exposure in wild-type and SOS-deficient Escherichia coli

The SOS response in UV-irradiated Escherichia coli includes the upregulation of several dozen genes that are negatively regulated by the LexA repressor. Using DNA microarrays containing amplified DNA fragments from 95.5% of all open reading frames identified on the E. coli chromosome, we have examined the changes in gene expression following UV exposure in both wild-type cells and lexA1 mutants, which are unable to induce genes under LexA control. We report here the time courses of expression of the genes surrounding the 26 documented lexA-regulated regions on the E. coli chromosome. We observed 17 additional sites that responded in a lexA-dependent manner and a large number of genes that were upregulated in a lexA-independent manner although upregulation in this manner was generally not more than twofold. In addition, several transcripts were either downregulated or degraded following UV irradiation. These newly identified UV-responsive genes are discussed with respect to their possible roles in cellular recovery following exposure to UV irradiation.

[Ultrasound diagnosis of face and neck organs]

Sonography of the neck and face is highly suited for confirming visible, palpable or generally tentative findings. A method of performing a systematic examination will be described in detail and followed by numerous examples descriptive of soft tissue pathologies of the face, salivary glands and lymph nodes. The thyroid gland will be dealt with in a different report. The criterion that applied to all masses was that it was only possible to render a tentative diagnosis to be subsequently confirmed by sonography-guided fine-needle aspiration. Histological follow-up, however, was never excluded. If a finding could not be narrowed down by sonography, the next step was to use computerized or nuclear magnetic resonance imaging.

Isolation of Escherichia coli mRNA and comparison of expression using mRNA and total RNA on DNA microarrays

Bacterial messenger RNA (mRNA) is not coherently polyadenylated, whereas mRNA of Eukarya can be separated from stable RNAs by virtue of polyadenylated 3'-termini. We have developed a method to isolate Escherichia coli mRNA by polyadenylating it in crude cell extracts with E. coli poly(A) polymerase I and purifying it by oligo(dT) chromatography. Differences in lacZRNA levels were similar with purified mRNA and total RNA in dot blot hydridizations for cultures grown with or without gratuitous induction of the lactose operon. More broadly, changes in gene expression upon induction were similar when cDNAs primed from mRNA or total RNA with random hexanucleotides were hydridized to DNA microarrays for the E. coli genome. Comparable signal intensities were obtained with only 1% as much oligo(dT)-purified mRNA as total RNA, and hence in vitro poly(A) tailing appears to be selective for mRNA. These and additional studies of genome-wide expression with DNA microarrays provide evidence that in vitro poly(A) tailing works universally for E. coli mRNAs.

[Cervicofacial necrotizing fasciitis]

INTRODUCTION

Necrotising fasciitis is still a severe disease whose outcome is occasionally fatal.

METHODS

Between August 1994 and August 1998, 6 patients with necrotising fasciitis, 5 in the neck area and one in the facial area, were treated. The source of the infection was odontogenic in 3 cases, pharyngeal in 2 and an insect sting in the left upper eyelid in one case.

RESULTS

Following evaluation by CT scan, immediate surgical exploration with debridement and drainage was performed. Revision proved necessary in most cases. One patient suffered severe complications. Median stay in the intensive care unit was 7 days and in hospital 20 days.

DISCUSSION

Deep and extensive neck infections require investigation by CT scan. All affected areas must be explored and drained immediately, including thoracotomy if mediastinitis is present. Apart from appropriate antibiotic therapy, the further course of the disease should be carefully monitored to detect further spread of the infection as well as complications.