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.

SIGNIFICANCE OF A T-LYMPHOCYTOTOXIC CROSSMATCH IN LIVER AND COMBINED LIVER-KIDNEY TRANSPLANTATION

BACKGROUND

In contrast to kidney transplants a positive crossmatch is no contraindication for liver transplantation (OLT). In liver transplantation, antibody mediated rejections are rarely reported and a liver graft is suspected to have protective effects for kidney grafts when transplanted simultaneously. The aim of this study was to evaluate the effect of a positive crossmatch on outcome after OLT and combined liver and kidney transplantation (CLKTx).

METHODS

We analyzed retrospectively the impact of a positive crossmatch on graft survival and rejection episodes after OLT (793pats) and CLKTx (18pats, 2.2%). Immunosuppression consisted of either Cyclosporine- or Tacrolimus-based regimens.

RESULTS

A total of 50/811 (6%) of patients had a positive crossmatch, 45/793 (5.6%) with liver transplantation alone and 5/18 (28%) of patients with CLKTx. Follow-up ranged from 1 to 122.5 months (median 45.8 months). One- and 5-year graft survival rates of liver transplants alone with a positive crossmatch were 89.6% and 75.3%, respectively and were 88% and 77.5% in crossmatch negative recipients. Additionally, the incidence of acute and steroid-resistant rejection (44% and 15.5%) was not significantly increased in patients with a positive crossmatch when compared with patients with a negative crossmatch (38% and 19%). None of the patients with a positive crossmatch and CLKTx underwent a hyperacute-rejection episode after transplantation, and kidney graft survival 100%.

CONCLUSIONS

In conclusion, a positive crossmatch is no contraindication for OLT and CLKTx. Furthermore, not having to wait for results of donor/recipient crossmatching can shorten cold ischemia time and may improve the clinical outcome.

Diatom fucoxanthin chlorophyll a/c-binding protein (FCP) and land plant light-harvesting proteins use a similar pathway for thylakoid membrane Insertion

The light-harvesting proteins in plastids of different lineages including algae and land plants represent a superfamily of chlorophyll-binding proteins that seem to be phylogenetically related, although some of the light-harvesting complex (LHC) proteins bind different carotenoids. LHCs can be divided into chlorophyll a/b-binding proteins found in green algae, euglenoids, and higher plants and into chlorophyll a/c-binding proteins of various algal taxa. LHC proteins from diatoms are named fucoxanthin-chlorophyll a/c-binding proteins (FCP). In contrast to chlorophyll a/b-binding proteins, there is no information so far about the way FCPs integrate into thylakoid membranes. The diatom FCP preproteins have a bipartite presequence that is necessary to enable transport into the four membrane-bound diatom plastids, but similar to chlorophyll a/b-binding proteins there is apparently no presequence present for targeting to the thylakoid membrane. By establishing an in vitro import assay for diatom thylakoids, we demonstrated that thylakoid integration of diatom FCP depends on the presence of stromal factors and GTP. This indicates that a pathway involving signal recognition particles (SRP) is involved in membrane integration just as shown for LHCs in higher plants. We also demonstrate integration of diatom FCP into thylakoids of higher plants and vice versa SRP-dependent targeting of LHCs from pea and Arabidopsis into diatom thylakoids. The similar SRP-dependent modes of thylakoid integration of land plant LHCs and FCPs support recent analyses indicating a common origin of chlorophyll a/b- and a/c-binding proteins.

Staggered field effect on the one-dimensional S = 1/2 antiferromagnet Yb4As3

Inelastic neutron scattering measurements of magnetic excitations in the charge-ordered state of Yb4As3 have been performed under magnetic field up to about 6 T. By applying a magnetic field, the spectrum at the one-dimensional wave vector q = 1 [ pi/d] changes drastically from a broad one corresponding to the spinon excitation continuum of the one-dimensional S = 1 / 2 spin system to a sharp one at a finite energy, indicating the opening of an energy gap in the system. The magnetic field dependence of the gap is well fitted by the power law H2/3. The experimental result gives strong evidence for the existence of a staggered field alternating along Yb3+ chains induced by the Dzyaloshinsky-Moriya interaction.

Context conditioning and run-length coding for hybrid, embedded progressive image coding

An analysis of spatial context conditioning and run-length coding in embedded progressive, wavelet-based image coding is presented. The analysis shows that run-length coding of certain context subsequences is superior to pure entropy coding, both in terms of coding performance and of execution speed. Based on these considerations, a novel, intuitive context conditioning scheme using a spatial distance model to describe the statistics of significant coefficients is proposed. The results for the proposed coding scheme are competitive to the best coding schemes found in the literature.

3D-reconstruction of craniofacial structures of a human anencephalic fetus. Case report

It was the purpose of this study to investigate the craniofacial bones, cartilages and major blood vessels of a human anencephalic fetus and to describe the malformations of these structures accompanying this developmental disruption. The head of a 16 week old human fetus with anencephaly was serially sectioned and the craniofacial bones, cartilages and major blood vessels were traced and reconstructed by 3D-computer technology. The sphenoidal, temporal and occipital bones showed severe malformations, whereas the bones of the facial cranium were normally developed. Both internal carotid arteries ended within the cerebro-vascular area with no further branches. The vertebral arteries also ended within the cerebro-vascular area. No arterial circle of Willis was developed. The notochord terminated normally in the sphenoid body. The observations indicate that the possible reason for this malformation was non-closure of the anterior neuropore of the neural tube. The normal termination of the notochord suggests that it had no influence on the pathogenesis of this malformation. The malformations of the temporal and occipital bones are contradictory to the hypothesis of Marin-Padilla (1991) that anencephaly is caused by a maldevelopment of the sphenoidal bone.

Fast variable run-length coding for embedded progressive wavelet-based image compression

Run-length coding has attracted much attention in wavelet-based image compression because of its simplicity and potentially low complexity. The main drawback is the inferior RD-performance compared to the state-of-the-art-coder SPIHT. In this paper, we concentrate on the embedded progressive run-length code of Tian and Wells (1996, 1998). We consider significance sequences drawn from the scan in the dominant pass. It turns out that self-similar curves for scanning the dominant pass increase the compression efficiency significantly. This is a consequence of the correlation of direct neighbors in the wavelet domain. This dependence can be better exploited by using groups of coefficients, similar to the SPIHT algorithm. This results in a new and very fast coding algorithm, which shows performance similar to the state-of-the-art coder SPIHT, but with lower complexity and small and fixed memory overhead.

Compatibility of different colloid plasma expanders with perflubron emulsion: an intravital microscopic study in the hamster

BACKGROUND

Perfluorocarbon-based oxygen carriers have been proposed as an adjunct to autologous blood conservation techniques during elective surgery. To date, the effects of perfluorocarbon emulsions at the microcirculatory level have not been studied extensively. In this study the effects of perflubron emulsion on the microcirculation after acute normovolemic hemodilution (ANH) were investigated using different colloid plasma expanders.

METHODS

The dorsal skin fold chamber model and intravital fluorescence microscopy were used for analysis of the microcirculation in the thin striated skin muscle of conscious hamsters (body weight, 40-60 g). Measurements of microvascular perfusion and leukocyte adhesion (n = 6 animals per experimental group) were made before and at 10, 30, and 60 min after ANH (to hematocrit 0.3) with either 6% hydroxyethyl starch 200/0.6 (HES), 3.5% gelatin, 5% human serum albumin (HSA), or 6% dextran 60 (DX-60) followed by intravenous injection of 3 ml/kg body weight of a 60% weight/volume perfluorocarbon emulsion based on perflubron (perfluorooctyl bromide) emulsified with egg yolk lecithin.

RESULTS

Acute normovolemic hemodilution with HES, gelatin, or HSA followed by injection of perflubron emulsion elicited no alterations of local microvascular perfusion or leukocyte-endothelium interaction as assessed in arterioles and postcapillary venules. However, ANH with DX-60 followed by injection of perflubron emulsion led to a significant reduction of erythrocyte velocity in postcapillary venules and an increase in venular leukocyte sticking that was never observed with DX-60 alone.

CONCLUSIONS

Hydroxyethyl starch, gelatin, and HSA are compatible with perflubron emulsion in the setting of ANH. Only DX-60 appeared to be incompatible with perflubron emulsion, as evidenced by impairment of capillary perfusion.

Three-dimensional analysis of measurements of the Heidelberg Retina Tomograph

BACKGROUND

With the aid of scanning laser tomography, feasible with the Heidelberg Retina Tomograph (HRT), refined structures can be measured three-dimensionally. Pictures are built up from scanned layers which are represented as two-dimensional topographical or reflectivity pictures by the HRT software. The kind of information that is provided by the third dimension can be exploited much better by real spatial three-dimensional presentation. The autostereoscopic Dresden 3D display makes such a spatial presentation feasible as add-on to the HRT.

METHODS

Seventeen patients (9 women, 8 men) were chosen on the basis of a long duration of observation (mean 42.41 months) and a large number of follow-up examinations (mean 5.29). These patients were examined with the HRT as well as with the Dresden 3D display. The results were compared regarding their correlation pairs.

RESULTS

Comparing the correlation pairs (r>0.7) the Dresden 3D display provided a higher Pearson correlation coefficient with 8 out of 10 pairs. It was evident that the evaluations of the two devices referred to the same parallel structures.

DISCUSSION

The Dresden 3D display facilitates, with its form of presentation, a better evaluation of the measurements of the HRT. More precise evaluation of retinal structures by virtue of the autostereoscopic display presents an improvement.

Lung cancer risk in nonsmokers and GSTM1 and GSTT1 genetic polymorphism

Glutathione S-transferase (GST) polymorphism may contribute to the individual variability in detoxifying lung carcinogens. This effect might be particularly relevant at low-level exposure to environmental carcinogens, such as in nonsmokers exposed to environmental tobacco smoke (ETS). We conducted a case-control study among 122 nonsmoking lung cancer cases and 121 nonsmoking controls from eight countries. Information on environmental exposures was obtained through a personal interview. The presence of GSTM1 and GSTT1 genes was determined using multiplex PCR. GSTM1-positive samples were then analyzed for *1A and *1B polymorphism using an allele-specific amplification-PCR method. GSTM1*2 (null) individuals had an odds ratio (OR) of lung cancer of 1.5 [95% confidence interval (CI), 0.9-2.7]; the risk associated with this genotype was higher for cases with squamous and small cell carcinomas (OR, 2.3; 95% CI, 0.9-6.1) than for cases with adenocarcinomas. It was also elevated in individuals with long-term exposure to indoor wood combustion (OR, 3.1; 95% CI, 0.9-9.9), in subjects who mainly lived in a rural setting (OR, 3.6; 95% CI, 1.0-13), and in cases exposed to occupational carcinogens (OR, 10.7; 96% CI, 0.4-260) but not in subjects exposed to ETS. GSTT1*2 subjects did not show a risk of lung cancer. Our study suggests that the effect of GSTM1 polymorphism in nonsmokers is similar to that found in smokers. It does not seem to interact with ETS exposure, although we cannot exclude that it does in association with exposure to other specific environmental carcinogens.

YbRh(2)Si(2): pronounced non-fermi-liquid effects above a low-lyingmagnetic phase transition

We report the first observation of non-Fermi-liquid (NFL) effects in a clean Yb compound at ambient pressure and zero magnetic field. The electrical resistivity and the specific-heat coefficient of high-quality single crystals of YbRh(2)Si(2) present a linear and a logarithmic temperature dependence, respectively, in more than a decade in temperature. We ascribe this NFL behavior to the presence of (presumably) quasi-2D antiferromagnetic spin fluctuations related to a very weak magnetic phase transition at T(N) approximately 65 mK. Application of hydrostatic pressure induces anomalies in the electrical resistivity, indicating the stabilization of magnetic order.

Helicity dependence of gammap --> Npi below 450 MeV and contribution to the Gerasimov-Drell-Hearn sum rule

The helicity dependence of the single pion photoproduction on the proton has been measured in the energy range from 200 to 450 MeV for the first time. The experiment, performed at the Mainz microtron MAMI, used a 4pi-detector system, a circularly polarized, tagged photon beam, and a frozen-spin target. The data obtained provide new information for multipole analyses of pion photoproduction and determine the main contributions to the Gerasimov-Drell-Hearn sum rule and the forward spin polarizability gamma(0).

New anilinophthalazines as potent and orally well absorbed inhibitors of the VEGF receptor tyrosine kinases useful as antagonists of tumor-driven angiogenesis

The sprouting of new blood vessels, or angiogenesis, is necessary for any solid tumor to grow large enough to cause life-threatening disease. Vascular endothelial growth factor (VEGF) is one of the key promoters of tumor induced angiogenesis. VEGF receptors, the tyrosine kinases Flt-1 and KDR, are expressed on vascular endothelial cells and initiate angiogenesis upon activation by VEGF. 1-Anilino-(4-pyridylmethyl)-phthalazines, such as CGP 79787D (or PTK787 / ZK222584), reversibly inhibit Flt-1 and KDR with IC(50) values < 0.1 microM. CGP 79787D also blocks the VEGF-induced receptor autophosphorylation in CHO cells ectopically expressing the KDR receptor (ED(50) = 34 nM). Modification of the 1-anilino moiety afforded derivatives with higher selectivity for the VEGF receptor tyrosine kinases Flt-1 and KDR compared to the related receptor tyrosine kinases PDGF-R and c-Kit. Since these 1-anilino-(4-pyridylmethyl)phthalazines are orally well absorbed, these compounds qualify for further profiling and as candidates for clinical evaluation.

[Female pseudohermaphroditism in congenital adrenogenital syndrome as an incidental intraoperative finding in a 68 year old patient]

HISTORY AND CLINICAL FINDINGS

A 68-year-old man of small stature, previously always healthy and with a grown-up daughter, was suspected of having carcinoma of the colon with metastasis to the right kidney. At laparotomy internal female genitalia with cancerous changes were unexpectedly discovered in the left adnexae. The colon carcinoma, the right adrenocortical tumour and left adnexae were resected.

INVESTIGATIONS

Histological examination revealed adenocarcinoma of the colon, right adrenocortical adenoma and a Brenner tumour of the left female adnexae. Postoperative tests showed increased levels of 17-OH-progesterone (3192 ng/dl), 21-desoxycortisol (1856 ng/dl) and of adrostenedione (745 ng/dl), while the concentrations of 17-OH pregnenolone, testosterone and mineralocorticoids were within normal limits. Chromosome analysis demonstrated karyotype 46 XX.

DIAGNOSIS, TREATMENT AND COURSE

As far as could be ascertained, this is the first documented case in the German-speaking region of female pseudohermaphroditism diagnosed in an elderly person with uncomplicated virilizing congenital adrenogrenital syndrome due to 21-hydroxylase deficiency (deletion of CYP21 gene). To avoid a cortisone deficiency crisis the patient was regularly given hydrocortisone and he quickly recovered. But he died 6 months later of sequelae of the carcinoma of the colon.

CONCLUSION

An adrenogenital syndrome should be excluded in a case of bilateral adrenocortical tumour. As this is usually benign, conservative treatment should be attempted. This case demonstrates the necessity of thorough examination which could have given an early indication of the underlying condition.

[Intraocular pressure response after administration of 3 different viscoelastic agents after cataract operation]

By using three different viscoelastics [Adatocel (methylhydroxypropylcellulose), Amvisc Plus (sodium hyaluronate) and Healon (sodium hyaluronate)] a prospective randomized study was conducted to investigate whether postoperative intraocular pressure shows significant differences according to the viscoelastics used after 150 cases of cataract surgery.

PATIENTS AND METHODS

The inclusion criteria for this study were: extracapsular cataract extraction via the usual small-incision techniques and endocapsular posterior-chamber lens implantation. A total of 150 eyes were operated upon. The patients were randomly assigned to three groups according to the viscoelastics, 50 cases used adatocel, 50 Amvisc Plus and 50 Healon. As far as possible, the viscoelastics were sucked out under visual control. Intraocular pressure (IOP) was measured after 6 and 24 h.

RESULTS

Six hours postoperatively, no statistically significant difference between the intraocular pressure after using different viscoelastics (adatocel: 19.6 +/- 9.7 mmHg, Amvisc Plus: 20.5 +/- 9.6 mmHg und Healon: 21.8 +/- 8.8 mmHg) was seen. At 24 h IOP was statistically significant higher for Healon than for adatocel and Amvisc Plus (adatocel: 16.3 +/- 4.8 mmHg, Amvisc Plus: 16.5 +/- 4.6 mmHg and Healon: 19.7 +/- 6.6 mmHg).

CONCLUSIONS

Six hours postoperatively after phacoemulsification there was no significant difference between the IOP using different viscoelastics adatocel, Amvisc Plus and Healon. Twenty-four hours postoperatively a significantly higher intraocular pressure was measured for Healon than for the other viscoelastics.

Administration of prostacyclin after liver transplantation: a placebo controlled randomized trial

The shortage of suitable organs for liver grafts is responsible for the use of marginal donors for liver transplantation (OLT). If these liver grafts function poorly initially after OLT, a supportive therapy is necessary. The purpose of this study was to evaluate the effects of prostacyclin (PGI2) on postoperative liver graft function after OLT. A total of 30 adult recipients of primary OLT were randomized to either receive PGI2 (4 ng/kg per min body weight, n = 15) or a placebo for 6 d. To evaluate regional splanchnic oxygenation a fiberoptic pulmonary-artery catheter was inserted into a hepatic vein and the difference between mixed venous oxygen content and hepatic venous oxygen content was determined (deltaO2). Measurements were performed directly after transplantation and at 6, 12, 24 and 48 h postoperatively. A significant correlation between deltaO2 and the level of transaminases (ALT/AST) was observed 24 and 48 h after transplantation (p < 0.05). PGI2 treatment induced a significant decrease in deltaO2 after 24 and 48 h after reperfusion (p < 0.05). Peak AST levels tended to be lower in the PGI2 treatment group (418 +/- 99 vs. 638 +/- 156 U/L, p < 0.1). These results suggest that administration of PGI2 after OLT improves hepatic-splanchnic oxygenation and may thereby reduce reperfusion injury after OLT.

Development of a method for the determination of ultra-trace level mercury in adipose tissue by cold vapour atomic fluorescence spectrometry

A method for the determination of total mercury in rat adipose tissue by cold vapour atomic fluorescence spectrometry (CVAFS) has been developed. Adipose samples were initially subjected to a lyophilization procedure in order to facilitate the homogenization and accurate weighing of small tissue aliquots (approximately 50 mg). A closed vessel microwave digestion procedure using a mixture of sulphuric and nitric acids was used to liberate mercury from the adipose matrix. All mercury species were quantitatively oxidized to Hg(II) by a potassium bromate/bromide oxidation, then reduced to Hg(0) vapour by stannous chloride prior to fluorescence detection. The CVAFS exhibited a linear range of 10 pg Hg/ml to 120 pg Hg/ml. The method detection limit in solution was 2 pg Hg/ml, or 1 ng Hg/g adipose tissue, based on a nominal 50 mg sample and a final volume of 25 ml. A reference material from the National Research Council of Canada (DOLT-2, trace metals in dogfish liver) was prepared in quadruplicate in order to assess the accuracy and precision of the method. Mercury in this material was recovered at 2.22 +/- 0.08 microg/g, which is 104% of the certified level (2.14 +/- 0.10 microg/g).

Intra-atrial communication and control of atrial natriuretic factor (ANF) release

Atrial natriuretic factor (ANF) release was studied in isolated perfused atria prepared from rats. When the vein-atrial junction (VAJ) was distended with an inflatable balloon, ANF release into the perfusate was greater in intact atria than in appendectomized atria. It was concluded that distention of the VAJ causes ANF release from the atrial appendage. A cascade experiment was then prepared whereby buffer from one isolated atrium perfused a second atrium. Although the VAJ of the first atrium could be distended by balloon, the atrial appendage was ligated so ANF was not secreted into the perfusate. The second atrium was intact, but no balloon was inserted. Despite the fact that there were no changes in intraluminal pressure, ANF secretion from the second atrium increased when the VAJ of the first atrium was distended. This response was blocked by the endothelin (ET) A receptor antagonist BQ-123. However, no distention-induced changes in ET-1 levels could be found in the perfusate from the first atrium. It is proposed that, in response to changes in distention of the VAJ, ANF is released remotely from the atrial appendage. The mediator does not appear to be ET-1 itself, but rather some factor that stimulates ET-1-induced ANF release within the tissue of the atrial appendage.

Metabolism of xenobiotics and chemical carcinogenesis

In order to avoid the accumulation of harmful xenobiotics in cells, living organisms have developed ways for their elimination. Multiple xenobiotic metabolizing enzymes with variable but partially overlapping catalytic properties play a key role in the elimination process. These enzymes are encoded by superfamilies of genes which, during the course of evolution, have evolved in a way that has made it possible for the different species to survive and take advantage of different habitats and diet containing a variable composition of harmful xenobiotics. As a result of this evolutionary process, species have achieved capacities to metabolize xenobiotics which are appropriate for their survival but which may differ considerably from those of other species. This evolutionary process may also explain the interethnic and interindividual variability of drug metabolism in humans. Because many carcinogens are substrates of drug-metabolizing enzymes it is reasonable to assume that humans have a variable capacity to activate or inactivate carcinogens. This has been shown to be the case. It appears that most of the carcinogen-metabolizing enzymes are inducible by xenobiotics: they respond to environmental stimuli and therefore vary in their activity. Furthermore, many of the encoding genes are polymorphic and multiple allelic variants relevant for the phenotype may exist in human populations. Analysis of the genetic variability that affects the capacity to metabolize carcinogens in humans has shown that a few members of the cytochrome P450, glutathione S-transferase and N-acetyltransferase gene families may play an Important role in chemical carcinogenesis. Yet for several enzymes such a role has not been established until now, although their catalytic properties and expression in human tissues suggest that such a role should exist. More studies on the role of individual enzymes in chemical carcinogenesis are therefore warranted.

Xenobiotic-metabolizing enzymes and cancer risk: correspondence between genotype and phenotype

Metabolic activation and/or inactivation of a carcinogen is usually studied in appropriate in vitro systems but ultimately needs confirmation from in vivo studies, i.e. phenotype studies. It determines what initially happens to a carcinogen to which an organism is exposed. Consequently, it is of major importance to investigate the correspondence between any particular genotype of a carcinogen-metabolizing enzyme and its phenotypic expression, if any. The need to elucidate the relationship between genotype and phenotype is particularly important now, when methods for uncovering changes in genomic DNA are rather easy, even routine. There are several examples where the correspondence between a variant allele and an altered phenotype, measured by a probe drug or by some other means, has been elucidated (e.g. several alleles of CYP2D6). However, there are also cases where this correspondence has either not been studied (sometimes because of a lack of suitable probe substances) or has remained unclear (e.g. CYP1A1 or CYP2E1), despite case-control studies demonstrating an association between a variant allele and cancer risk. In the end one has to address the basic question as to how the genotype determines the phenotype and whether there is any biologically plausible link between the genotypic differences and cancer susceptibility. A knowledge of the complete sequence of events, from the gene to the outcome, would be helpful in unravelling the implications and possible preventive and treatment strategies to be employed in cases where clear associations between carcinogen-metabolizing enzymes and cancer susceptibility have been uncovered.

[Initial clinical experiences with the Dresden 3D display in conjunction with the Heidelberg Retina Tomograph (HRT)]

BACKGROUND

For years the Heidelberg Retina Tomograph has been an established method to diagnose early glaucomatous damages at the optic nerve head. The major difficulty consists in defining the outlayer of the optic nerve head in a 2-dimensional reflective or topographic picture. A 3-dimensional presentation of the ocular fundus could ease the defining very much. The Dresden 3D-display tested provides a true 3-dimensional presentation of the HRT-values measured.

METHODS

For the study 5 groups of prediagnosed follow-up examinations were formed, which in their course showed various progression. The examination firstly was carried out by manual defining of the papilla contour on the Dresden 3D-display and secondly by the new automatic contour-finding of the 3D-software.

RESULTS

Through the 3-dimensional presentation a more correct position of the contour can be found when drawn manually. As a result some diagnoses of the 2-dimensional HRT-pictures had to be revised. The results proved considerable differences between the automatic outlayer-finding and the probably real position of the papilla borders.

CONCLUSION

The 3-dimensional presentation of the HRT-pictures represents an subjective improvement regarding the accuracy of manual contour definition. In particular, the fact that it is feasible to make the pictures rotate around the axes offers completely new insights to the morphology of the disc.

Professional cooperation between dentist and laboratory technician

This case points out the importance of professional cooperation between the dentist and the technician because of the concept that implantology means specialized prosthetics including a surgical component. Success of any implant treatment depends on the professionally trained technician as a partner of the team. Clinical and technical treatment steps are intertwined. The dentist is responsible for the surgical procedure and must use his or her utmost skills and learning. In cases of proposed sinus elevation on both sides of the maxilla, the dentist must not necessarily collect autologous bone from the iliac crest because appropriate bone substitutes are available; also, tuber blades may be used to avoid sinus elevation. Unfortunately, at this time, the universities in Germany have not endeavored to pursue intensive scientific research concerning this important topic.

Synthesis and characterization of polycaprolactone/poly(ethylene oxide)/polylactide tri-componet copolymers

Polycaprolactone/poly(ethylene oxide)/polylactide tri-component copolymers (PCEL) with different compositions were synthesized by copolymerization of epsilon-caprolactone and L-lactide in the presence of poly(ethylene glycol) using stannous octoate as a catalyst. The copolymers were purified and characterized by various analytical techniques such as GPC, FT-IR, 1H NMR, 13C NMR, DSC, and X-ray diffractometry. It was evidenced that these copolymers were pure tri-component compounds which exhibited partially random chain structures, and possessed good mechanical properties and variable biodegradability.

[Endothelial dysfunction and lipid profiles: analysis of the EDO Study]

On the basis of experimental as well as clinical observations, endothelial dysfunction is (defined as impaired or absent endothelium-dependent relaxation) considered to be an important factor in the atherogenesis. Serum lipids abnormalities have been accepted as an epidemiological risk factor of atherosclerosis. In vitro, experimental as well as epidemiological studies revealed the fact, that lipoprotein oxidation plays an important role in atherogenesis. Recently invented non-invasive methods to test and measure the endothelial function in vivo opened the opportunity to study the influence of different serum lipids on the endothelial function directly. Therefore, we decided to employ this non-invasive method for studying the endothelial function and observe the influence of various levels of plasma lipids and lipoprotein oxidation on the endothelial function of arteries in middle-aged men, since they are the most endangered part of population. In our study we used a method of measuring the diameter of a. radialis by high-resolution ultrasound (Sonoline 450, Siemens, Japan) and further mathematical and statistical analysis of functional as well as relative vasodilation reserve followed these measurements. Blood samples were taken within 24 hours of ultrasonography to study serum lipids (total cholesterol, HDL, triglycerides) and parameters of oxidation/antioxidation (superoxid dismutase--SOD, malondialdehyde--MDA). Sixty men, 25-45 years old, from an area of basically the same level of pollution were examined. We found a negative correlation between FVDR and TCH (p = 0.01), FVDR and Tg (p = 0.002) and FVDR a TCH/HDL (p = 0.015). Positive correlation exists (p < 0.001) between TCH, Tg levels and TCH/HDL ratio and MDA level in all cases. Analysing further data from the EDO Study, we can conclude, that increased plasma lipids are more likely to be oxidized, which, in turn, is the probable reason of endothelium-dependent vasodilation impairment.

[Complications of percutaneous liver biopsy in patients after liver transplantation]

Percutaneous liver biopsy is an important diagnostic tool for the management of patients following liver transplantation. However, it may be associated with severe complications. To evaluate the incidence and type of complications after liver biopsy, we retrospectively analyzed 919 patients who underwent orthotopic liver transplantation (OLT) from September 1988 to May 1998. A total 3,670 biopsies were performed with ultrasound guidance and use of the Menghini needle (1.6 mm diameter). The biopsies were performed according to the protocol on the 7th postoperative day and one, three, five years after OLT, or when clinically indicated. Patients with severe coagulopathy (thrombocytes < 30,000/nl and Quick < 40%) were excluded from this protocol. Biopsy was complicated by bleeding in 13 of 919 patients (1.41%). The incidence of procedure related complications was 13 of 3,670 (0.35%). Five patients showed intrahepatic hematoma, four patients developed a hematothorax, three patients had intraabdominal bleeding and one patient suffered from hemobilia. Seven of 13 patients (53%) required surgical intervention (laparotomy four, thoracotomy two, retransplantation one). Graft dysfunction after liver transplantation requires rapid assessment and specific treatment to achieve good results. Percutaneous liver biopsy is an important procedure in the evaluation and identification of graft dysfunction such as acute rejection, hepatitis reinfection or toxic alterations. From our data we conclude that percutaneous liver biopsy is a safe procedure and advocate is liberal use.

[Treatment of advanced Budd-Chiari syndrome by liver transplantation]

Budd-Chiari syndrome (BCS) with hepatic vein occlusion is a rare disorder that can effectively be treated in advanced stages with orthotopic liver transplantation. We report on 16 patients who received 18 liver grafts and were followed up for at least 2 years. In 7 patients a hematological disorder was confirmed by bone marrow biopsy. One patient died after 4 months due to cytomegalovirus pneumonia; another patient died after 2 years due to progressive liver failure after portal vein thrombosis. The actuarial 5-year survival rate is 87.5% compared to 85.3% in all other 710 orthotopic liver transplantations performed from September 1988 to December 1995 at our institution. Anticoagulation consisted of intravenous heparin and overlapping continuation with dicoumarin. Three patients received hydroxyurea for thrombocytosis, one patient for 1 week only early after the transplantation. Two postoperative abdominal hemorrhages required laparotomy. Two patients had to be retransplanted, one for thrombosis of the hepatic artery and portal vein after discontinuation of dicoumarin due to GI bleeding and one for hepatic vein thrombosis after insufficient dicoumarin intake. Terminal BCS represents a good indication for orthotopic liver transplantation; however, life-long, closely monitored anticoagulation is essential.

Protein transport into "complex" diatom plastids utilizes two different targeting signals

The plastids found in diatoms and other chromophytic algae are completely enclosed by four membranes in contrast to chloroplasts of higher plants, which are surrounded by only two membranes. The bipartite targeting sequence of diatom nuclear-encoded plastid proteins contains an endoplasmic reticulum signal sequence and, based on sequence comparison, a transit peptide-like domain similar to that which targets proteins into the plastids of higher plants. By performing heterologous import experiments using the precursor of the gamma subunit of the chloroplast ATPase from the diatom Odontella sinensis we were able to show that protein import into diatom plastids is at least a two-step event. We demonstrate that the first step involves co-translational transport through endoplasmic reticulum membranes and that there is an additional targeting step which is similar to the import of precursor proteins into chloroplasts of higher plants and green algae indicating that the transit peptide-like domain of the diatom precursor is functionally equivalent to the respective targeting signal of higher plants. Our results suggest that the transit peptide depending targeting mechanism in plastids has apparently remained relatively unchanged over the course of evolution, with only the peptidase cleavage site significantly modified.

New aza-dipeptide analogues as potent and orally absorbed HIV-1 protease inhibitors: candidates for clinical development

On the basis of previously described X-ray studies of an enzyme/aza-dipeptide complex,8 aza-dipeptide analogues carrying N-(bis-aryl-methyl) substituents on the (hydroxethyl)hydrazine moiety have been designed and synthesized as HIV-1 protease inhibitors. By using either equally (12) or orthogonally (13) protected dipeptide isosteres, symmetrically and asymmetrically acylated aza-dipeptides can be synthesized. This approach led to the discovery of very potent inhibitors with antiviral activities (ED50) in the subnanomolar range. Acylation of the (hydroxethyl)hydrazine dipeptide isostere with the L-tert-leucine derivative 29 increased the oral bioavailability significantly when compared to the corresponding L-valine or L-isoleucine derivatives. The bis(L-tert-leucine) derivatives CGP 75355, CGP 73547, CGP 75136, and CGP 75176 combine excellent antiviral activity with high blood concentration after oral administration. Furthermore, they show no cross-resistance with saquinavir-resistant strains and maintain activity against indinavir-resistant ones. Consequently they qualify for further profiling as potential clinical candidates.

Nonfluoroscopic endocardial catheter mapping of atrial fibrillation

The treatment of drug-refractory atrial fibrillation (AF) remains one of the unsolved problems in cardiology. Surgical interventions have demonstrated that AF can be prevented by multiple incisions within both atria. Recently, this strategy has been translated into a catheter procedure. So far, the ablation approach is not based on individual electrophysiologic data, but constitutes only an anatomic approach. Further insight into the spatial and temporal distribution of the local electrograms during AF is needed. Electroanatomic maps acquired by sequential mapping over 45 seconds at each site during AF in six patients with paroxysmal AF were analyzed off-line. Electrograms were sampled at a mean of 36 +/- 12 sites in the left atrium of each patient. A total of 217 sites were sampled, of which 27.3% (59) represented type A (regular) AF, 9.7% (21) represented type B (totally irregular), and 63.1% (137) represented type C (mixture of type A and B) electrograms. The distribution was analyzed in 20 different segments of the left atrium, and a significantly higher incidence of type A electrograms was found in area 3 (upper lateral pulmonary vein) than at all other sites (P < 0.005). This observation needs further confirmation before any conclusion with regard to catheter ablation can be drawn, particularly because the analysis was based on bipolar recordings from a 4-mm tip electrode.

Combined liver-kidney transplantation: long-term follow up in 18 patients

Since August 1992, 18 patients underwent combined liver and kidney transplantation. Eight patients had lymphocytotoxic antibodies pretransplant and 5 of these patients (27.7%) had a positive crossmatch. Fifteen patients received cyclosporine-based immunosuppression and 3 patients were treated with a tacrolimus-based immunosuppressive protocol. One patient died in the postoperative course due to intractable bleeding episodes after 96 days and one kidney graft was lost due to technical complications. The 1 year survival rate of patients with combined transplantation was 95% vs 87% in patients with liver transplantation alone. None of the patients with a positive crossmatch experienced a hyperacute rejection of the kidney. The long-term patient and graft survival was not impaired in patients with a positive crossmatch. These results suggest that combined liver-kidney transplantation is a safe treatment for end-stage liver and renal disease. A positive crossmatch or positive lymphocytotoxic antibodies are not contraindications for a combined transplantation.