Production of enantiopure styrene oxide by recombinant Escherichia coli synthesizing a two-component styrene monooxygenase

A whole cell biocatalytic process was developed to enable the efficient oxidation of styrene to chiral (S)-styrene oxide with an enantiomeric excess better than 99%. Recombinant Escherichia coli cells were employed to express the genes styAB encoding the styrene monooxygenase of Pseudomonas sp. strain VLB120 from an expression plasmid utilizing the alk regulatory system of P. oleovorans GPo1. The strains reached specific activities of up to 70 U* (g cell dry weight)(-1) in shake-flask experiments with glucose as the carbon source. An efficient two-liquid phase fed-batch process was established for the production of (S)-styrene oxide with hexadecane as an apolar carrier solvent and a nutrient feed consisting of glucose, magnesium sulfate, and yeast extract. Engineering of the phase fraction and the composition of organic phase and feed led to a 2-L scale process with maximal volumetric productivities of 2.2 g (S)-styrene oxide per liter liquid volume per hour. This optimized process was based completely on defined medium and used bis(2-ethylhexyl)phthalate as the apolar carrier solvent, which together with substrate and inducer consisted of 50% of the total liquid volume. Using this system, we were able to produce per liter liquid volume 11 g of enantiopure (S)-styrene oxide in 10 h.

Lipoproteins and free plasma catecholamines in spinal cord injured men with different injury levels

Persons with spinal cord injury (SCI) are especially prone to atherogenesis. This is partly explained by an unfavourable lipoprotein profile in these individuals. The impairment of the sympathetic nervous system, and the fact that SCI subjects are subject to extreme physical inactivity, may have an influence on their lipid profile and lipoprotein(a) concentration. We made a detailed investigation of the lipid profile as well as serum levels of adrenaline and noradrenaline in 80 men with SCI ranging from tetraplegia to low paraplegia and in 16 control subjects. The lipid profile of tetraplegics was characterized by elevated very low-density lipoprotein cholesterol and triglyceride levels and reduced high-density lipoprotein levels. In contrast, paraplegics had significantly higher low-density lipoprotein and total cholesterol levels. Tetraplegics had lower and the low-lesion paraplegics had higher adrenaline and noradrenaline levels than the high-lesion paraplegics and the control subjects. High-lesion SCI subjects also showed an extreme reduction in VO2max. The lipoprotein profile was dependent on the injury level and serum catecholamine concentrations. The lower the noradrenaline values, the lower the high-density lipoprotein cholesterol. The low-density lipoprotein also correlated to catecholamines and particularly adrenaline values. Despite the correlation between lipoprotein(a) and adrenaline, no significant differences in lipoprotein(a) were found within SCI individuals as well as between SCI individuals and control subjects, indicating the predominantly genetic determination of lipoprotein(a) and thus the cardiovascular risk. Different serum catecholamine levels due to impairment of sympathetic nervous system and VO2max levels were observed in SCI subjects. This was associated with a higher lipid risk profile for cardiovascular diseases; however, the risk profile is dependent on the lesion level.

Haemoglobin, haematocrit and red blood cell indices in elite cyclists. Are the control values for blood testing valid?

BACKGROUND

In international cycling and cross-country skiing competitions, blood tests are used to unmask the performance enhancing misuse of erythropoietin. Haematocrit (cycling) and haemoglobin (cross-country skiing) limits have been set by international sporting federations (haematocrit 50%, haemoglobin 18.5 g/dl). Athletes tested above these cut-off values are declared unfit for competition. To investigate the validity of these regulations, we studied haemoglobin, haematocrit and red blood cell indices of elite cyclists before erythropoietin became commercially available.

MATERIAL AND METHODS

We investigated 523 blood samples of 92 male elite cyclists (age 16-31 years) from 1978 to 1987. Haematocrit, haemoglobin and red blood cell count were analysed automatically, erythrocyte indices were calculated.

RESULTS

Haemoglobin (-0.3 +/- 1 g/dl), haematocrit (-1.2 +/- 2.8%) and red blood cell count (-0.2 +/- 0.4 x 10(6)/mm3) decreased significantly (p < 0.05) with increasing training workload. The erythrocyte indices showed no significant change. Fifty-four blood samples (10.3%) showed a haematocrit above 50%, one sample presented a haemoglobin mass higher than 18.5 g/dl. During periods of increased workload, less athletes tested above the haematocrit limit.

CONCLUSION

The current haematocrit limit used in blood tests might lead to a high number of false positive tests.

Xylene monooxygenase catalyzes the multistep oxygenation of toluene and pseudocumene to corresponding alcohols, aldehydes, and acids in Escherichia coli JM101

Xylene monooxygenase of Pseudomonas putida mt-2 catalyzes the methylgroup hydroxylation of toluene and xylenes. To investigate the potential of xylene monooxygenase to catalyze multistep oxidations of one methyl group, we tested recombinant Escherichia coli expressing the monooxygenase genes xylM and xylA under the control of the alk regulatory system of Pseudomonas oleovorans Gpo1. Expression of xylene monooxygenase genes could efficiently be controlled by n-octane and dicyclopropylketone. Xylene monooxygenase was found to catalyze the oxygenation of toluene, pseudocumene, the corresponding alcohols, and the corresponding aldehydes. For all three transformations (18)O incorporation provided stong evidence for a monooxygenation type of reaction, with gem-diols as the most likely reaction intermediates during the oxygenation of benzyl alcohols to benzaldehydes. To investigate the role of benzyl alcohol dehydrogenase (XylB) in the formation of benzaldehydes, xylB was cloned behind and expressed in concert with xylMA. In comparison to E. coli expressing only xylMA, the presence of xylB lowered product formation rates and resulted in back formation of benzyl alcohol from benzaldehyde. In P. putida mt-2 XylB may prevent the formation of high concentrations of the particularly reactive benzaldehydes. In the case of high fluxes through the degradation pathways and low aldehyde concentrations, XylB may contribute to benzaldehyde formation via the energetically favorable dehydrogenation of benzyl alcohols. The results presented here characterize XylMA as an enzyme able to catalyze the multistep oxygenation of toluenes.

Gonadotropin-releasing hormone receptor initiates multiple signaling pathways by exclusively coupling to G(q/11) proteins

The agonist-bound gonadotropin-releasing hormone (GnRH) receptor engages several distinct signaling cascades, and it has recently been proposed that coupling of a single type of receptor to multiple G proteins (G(q), G(s), and G(i)) is responsible for this behavior. GnRH-dependent signaling was studied in gonadotropic alphaT3-1 cells endogenously expressing the murine receptor and in CHO-K1 (CHO#3) and COS-7 cells transfected with the human GnRH receptor cDNA. In all cell systems studied, GnRH-induced phospholipase C activation and Ca(2+) mobilization was pertussis toxin-insensitive, as was GnRH-mediated extracellular signal-regulated kinase activation. Whereas the G(i)-coupled m2 muscarinic receptor interacted with a chimeric G(s) protein (G(s)i5) containing the C-terminal five amino acids of Galpha(i2), the human GnRH receptor was unable to activate the G protein chimera. GnRH challenge of alphaT3-1, CHO#3 and of GnRH receptor-expressing COS-7 cells did not result in agonist-dependent cAMP formation. GnRH challenge of CHO#3 cells expressing a cAMP-responsive element-driven firefly luciferase did not result in increased reporter gene expression. However, coexpression of the human GnRH receptor and adenylyl cyclase I in COS-7 cells led to clearly discernible GnRH-dependent cAMP formation subsequent to GnRH-elicited rises in [Ca(2+)](i). In alphaT3-1 and CHO#3 cell membranes, addition of [alpha-(32)P]GTP azidoanilide resulted in GnRH receptor-dependent labeling of Galpha(q/11) but not of Galpha(i), Galpha(s) or Galpha(12/13) proteins. Thus, the murine and human GnRH receptors exclusively couple to G proteins of the G(q/11) family. Multiple GnRH-dependent signaling pathways are therefore initiated downstream of the receptor/G protein interface and are not indicative of a multiple G protein coupling potential of the GnRH receptor.

Differential effects of radical D2-lymphadenectomy and splenectomy in surgically treated gastric cancer patients

BACKGROUND/AIMS

Radical surgery with extended lymph node dissection (D2-LA) is the treatment of choice for gastric cancer patients in Japan. In Western countries results after D2-LA are controversially discussed, as increased D2-LA related complications are reported. The aim of this retrospective study was to analyze the influence of D2-LA and/or splenectomy on the clinical course, morbidity and long-term survival of gastric cancer patients.

METHODOLOGY

Included in this series are 243 consecutively treated gastric cancer patients with a median age of 63.8 years.

RESULTS

Though 56% of the patients presented with stage III and IV tumors, a resection rate of 95.5% with R0-resections in 73.7% was achieved. D2-LA rate was 66.3% with simultaneous splenectomy in 48.7%. Global morbidity was 41.6%. Surgical morbidity, leakage and abscess rates after curative R0 resections were not influenced by D2-LA (22.5/6.5/6.5% vs. 21.9/9.1/3.0% +/- LA) but by splenectomy (31.6/13.2/11.8% vs. 14.7/2.1/1% +/- Sx). Simultaneous splenectomy was associated with 7 of 9 leakages, 7 of 9 abscesses, and 4 of 5 cases with postoperative pancreatitis. Long-term survival (Kaplan-Meier) was 40.6% for all, and 58.1% for R0 resected patients. It was not influenced by splenectomy (56/60.3% +/- Sx).

CONCLUSIONS

Radical D2-LA has no impact on the morbidity of gastric cancer patients, but splenectomy is always linked with elevated complications without improving survival rates. Therefore splenectomy as potential part of D2-LA can only be advocated in patients with direct infiltration of pancreas or spleen, in stage IV or whenever metastatic spread is supposed in the nodes along splenic artery or hilum.

Receptor tyrosine phosphatases regulate axon guidance across the midline of the Drosophila embryo

Neural receptor-linked protein tyrosine phosphatases (RPTPs) are required for guidance of motoneuron and photoreceptor growth cones in Drosophila. These phosphatases have not been implicated in growth cone responses to specific guidance cues, however, so it is unknown which aspects of axonal pathfinding are controlled by their activities. Three RPTPs, known as DLAR, DPTP69D, and DPTP99A, have been genetically characterized thus far. Here we report the isolation of mutations in the fourth neural RPTP, DPTP10D. The analysis of double mutant phenotypes shows that DPTP10D and DPTP69D are necessary for repulsion of growth cones from the midline of the embryonic central nervous system. Repulsion is thought to be triggered by binding of the secreted protein Slit, which is expressed by midline glia, to Roundabout (Robo) receptors on growth cones. Robo repulsion is downregulated by the Commissureless (Comm) protein, allowing axons to cross the midline. Here we show that the Rptp mutations genetically interact with robo, slit and comm. The nature of these interactions suggests that DPTP10D and DPTP69D are positive regulators of Slit/Roundabout repulsive signaling. We also show that elimination of all four neural RPTPs converts most noncrossing longitudinal pathways into commissures that cross the midline, indicating that tyrosine phosphorylation controls the manner in which growth cones respond to midline signals.

HbpR, a new member of the XylR/DmpR subclass within the NtrC family of bacterial transcriptional activators, regulates expression of 2-hydroxybiphenyl metabolism in Pseudomonas azelaica HBP1

The regulation of 2-hydroxybiphenyl and 2,2'-dihydroxybiphenyl degradation in Pseudomonas azelaica is mediated by the regulatory gene, hbpR. The hbpR gene encodes a 63-kDa protein belonging to the NtrC family of prokaryotic transcriptional activators and having the highest homology to members of the XylR/DmpR subclass. Disruption of the hbpR gene in P. azelaica and complementation in trans showed that the HbpR protein was the key regulator for 2-hydroxybiphenyl metabolism. Induction experiments with P. azelaica and Escherichia coli containing luxAB-based transcriptional fusions revealed that HbpR activates transcription from a promoter (P(hbpC)) in front of the first gene for 2-hydroxybiphenyl degradation, hbpC, and that 2-hydroxybiphenyl itself is the direct effector for HbpR-mediated activation. Of several compounds tested, only the pathway substrates 2-hydroxybiphenyl and 2,2'-dihydroxybiphenyl and structural analogs like 2-aminobiphenyl and 2-hydroxybiphenylmethane were effectors for HbpR activation. HbpR is therefore, to our knowledge, the first regulator of the XylR/DmpR class that recognizes biaromatic but not monoaromatic structures. Analysis of a spontaneously occurring mutant, P. azelaica HBP1 Prp, which can grow with the non-wild-type effector 2-propylphenol, revealed a single mutation in the hbpR gene (T613C) leading to a Trp-->Arg substitution at amino acid residue 205. P. azelaica HBP1 derivative strains without a functional hbpR gene constitutively expressed the genes for 2-hydroxybiphenyl degradation when complemented in trans with the hbpR-T613C gene. This suggests the importance of this residue, which is conserved among all members of the XylR/DmpR subclass, for interdomain repression.

Low cytoplasmic [Ca(2+)] activates I(CRAC) independently of global Ca(2+) store depletion in RBL-1 cells

Release of Ca(2+) from inositol (1,4,5)-trisphosphate-sensitive Ca(2+) stores causes "capacitative calcium entry," which is mediated by the so-called "Ca(2+) release-activated Ca(2+) current" (I(CRAC)) in RBL-1 cells. Refilling of the Ca(2+) stores or high cytoplasmic [Ca(2+)] ([Ca(2+)](cyt)) inactivate I(CRAC). Here we address the question if also [Ca(2+)](cyt) lower than the resting [Ca(2+)](cyt) influences store-operated channels. We therefore combined patch clamp and mag fura-2 fluorescence methods to determine simultaneously both I(CRAC) and [Ca(2+)] within Ca(2+) stores of RBL-1 cells ([Ca(2+)](store)). We found that low [Ca(2+)](cyt) in the range of 30-50 nM activates I(CRAC) and Ca(2+) influx spontaneously and independently of global Ca(2+) store depletion, while elevation of [Ca(2+)](cyt) to the resting [Ca(2+)](cyt) (100 nM) resulted in store dependence of I(CRAC) activation. We conclude that spontaneous activation of I(CRAC) by low [Ca(2+)](cyt) could serve as a feedback mechanism keeping the resting [Ca(2+)](cyt) constant.

Mitochondria-derived and extra-mitochondrial human type-1 porin are identical as revealed by amino acid sequencing and electrophysiological characterisation

In mammalian cells porin channels are localised in both mitochondrial outer membranes and extra-mitochondrial membranes. We isolated mitochondria-derived porin of a human lymphoblastoid B cell line, determined its amino acid sequence and characterised its channel properties. Interestingly, the amino acid sequence of this porin preparation and, correspondingly, its electrophysiological characteristics in a reconstituted system were identical to those of 'Porin 31HL', the human type-1 porin purified from a crude membrane preparation of the same cell line using a different purification protocol. The results raise questions about targeting, insertion and orientation of human type-1 porin in different membranes.

Chromatin remodelling at the PHO8 promoter requires SWI-SNF and SAGA at a step subsequent to activator binding

The SWI-SNF and SAGA complexes possess ATP-dependent nucleosome remodelling activity and histone acetyltransferase (HAT) activity, respectively. Mutations that eliminate the ATPase activity of the SWI-SNF complex, or the HAT activity of SAGA, abolish proper chromatin remodelling at the PHO8 promoter in vivo. These effects are mechanistically distinct, since the absence of SWI-SNF freezes chromatin in the repressed state, while the absence of Gcn5 permits a localized perturbation of chromatin structure immediately adjacent to the upstream transactivator binding site. However, this remodelling is not propagated to the proximal promoter, and no activation is observed under all conditions. Furthermore, Pho4 is bound to the PHO8 promoter in the absence of Snf2 or Gcn5, confirming a role for SWI-SNF and SAGA in chromatin remodelling independent of activator binding. These data provide new insights into the roles of the SWI-SNF and SAGA complexes in chromatin remodelling in vivo.

Prevention of skin and soft tissue entrapment in tibial segment transportation

We report of a ten year old patient with soft tissue damage and bone defect of the tibia as a sequel of osteomyelitis. After excision and stabilization with an Ilizarov fixateur segment transportation was started. In order to avoid skin and soft tissue entrapment in the docking region, we used a metal cage as a space provider, which was shortened as segment transportation progressed. To our knowledge this simple method has not been described so far.

Pharmaco-toxicological mode of action of antimicrobial 5-nitroimidazole derivatives

5-Nitroimidazole derivatives are used as therapeutic agents against anaerobic microorganisms which are pathogenic to man and animals. The antimicrobial mode of action of these compounds is due to the metabolic reduction of the nitro group by microbial metabolism. By analogy, a reduction of the 5-nitro group in the aerobic animal metabolism is commonly assumed. This assumption is doubtful in its general form, and a more differentiated view is presented.

Clonal analysis of Drosophila embryonic neuroblasts: neural cell types, axon projections and muscle targets

An experimental analysis of neurogenesis requires a detailed understanding of wild-type neural development. Recent DiI cell lineage studies have begun to elucidate the family of neurons and glia produced by each Drosophila embryonic neural precursor (neuroblast). Here we use DiI labeling to extend and clarify previous studies, but our analysis differs from previous studies in four major features: we analyze and compare lineages of every known embryonic neuroblast; we use an in vivo landmark (engrailed-GFP) to increase the accuracy of neuroblast identification; we use confocal fluorescence and Nomarski microscopy to collect three-dimensional data in living embryos simultaneously for each DiI-labeled clone, the engrailed-GFP landmark, and the entire CNS and muscle target field (Nomarski images); and finally, we analyze clones very late in embryonic development, which reveals novel cell types and axon/dendrite complexity. We identify the parental neuroblasts for all the cell types of the embryonic CNS: motoneurons, intersegmental interneurons, local interneurons, glia and neurosecretory cells (whose origins had never been determined). We identify muscle contacts for every thoracic and abdominal motoneuron at stage 17. We define the parental neuroblasts for neurons or glia expressing well-known molecular markers or neurotransmitters. We correlate Drosophila cell lineage data with information derived from other insects. In addition, we make the following novel conclusions: (1) neuroblasts at similar dorsoventral positions, but not anteroposterior positions, often generate similar cell lineages, and (2) neuroblasts at similar dorsoventral positions often produce the same motoneuron subtype: ventral neuroblasts typically generate motoneurons with dorsal muscle targets, while dorsal neuroblasts produce motoneurons with ventral muscle targets. Lineage data and movies can be found at http://www.biologists.com/Development/movies/dev8623.htmlhttp://www.neuro.uoregon.edu/doelab/lineages/

Integrated two-liquid phase bioconversion and product-recovery processes for the oxidation of alkanes: process design and economic evaluation

Pseudomonas oleovorans and recombinant strains containing the alkane oxidation genes can produce alkane oxidation products in two-liquid phase bioreactor systems. In these bioprocesses the cells, which grow in the aqueous phase, oxidize apolar, non-water soluble substrates. The apolar products typically accumulate in the emulsified apolar phase. We have studied both the bioconversion systems and several downstream processing systems to separate and purify alkanols from these two-liquid phase media. Based on the information generated in these studies, we have now designed bioconversion and downstream processing systems for the production of 1-alkanols from n-alkanes on a 10 kiloton/yr scale, taking the conversion of n-octane to 1-octanol as a model system. Here, we describe overall designs of fed-batch and continuous-fermentation processes for the oxidation of octane to 1-octanol by Pseudomonas oleovorans, and we discuss the economics of these processes. In both systems the two-liquid phase system consists of an apolar phase with hexadecene as the apolar carrier solvent into which n-octane is dissolved, while the cells are present in the aqueous phase. In one system, multiple-batch fermentations are followed by continuous processing of the product from the separated apolar phase. The second system is based on alkane oxidation by continuously growing cultures, again followed by continuous processing of the product. Fewer fermentors were required and a higher space-time-yield was possible for production of 1-octanol in a continuous process. The overall performance of each of these two systems has been modeled with Aspen software. Investment and operating costs were estimated with input from equipment manufacturers and bulk-material suppliers. Based on this study, the production cost of 1-octanol is about 7 US$kg-1 when produced in the fed-batch process, and 8 US$kg-1 when produced continuously. The comparison of upstream and downstream capital costs and production costs showed significantly higher upstream costs for the fed-batch process and slightly higher upstream costs for continuous fermentation. The largest cost contribution was due to variable production costs, mainly resulting from media costs. The organisms used in these systems are P. putida alk+ recombinants which oxidize alkanes, but cannot oxidize the resulting alkanols further. Hence, such cells need a second carbon source, which in these systems is glucose. Although the continuous process is about 10% more expensive than the fed-batch process, improvements to reduce overall cost can be achieved more easily for continuous than for fed-batch fermentation by decreasing the dilution rate while maintaining near constant productivity. Improvements relevant to both processes can be achieved by increasing the biocatalyst performance, which results in improved overall efficiency, decreased capital investment, and hence, decreased production cost. Copyright 1999 John Wiley & Sons, Inc.

Cholecystokinin-evoked Ca(2+) waves in isolated mouse pancreatic acinar cells are modulated by activation of cytosolic phospholipase A(2), phospholipase D, and protein kinase C

We employed confocal laser-scanning microscopy to monitor cholecystokinin (CCK)-evoked Ca(2+) signals in fluo-3-loaded mouse pancreatic acinar cells. CCK-8-induced Ca(2+) signals start at the luminal cell pole and subsequently spread toward the basolateral membrane. Ca(2+) waves elicited by stimulation of high-affinity CCK receptors (h.a.CCK-R) with 20 pM CCK-8 spread with a slower rate than those induced by activation of low-affinity CCK receptors (l.a. CCK-R) with 10 nM CCK-8. However, the magnitude of the initial Ca(2+) release was the same at both CCK-8 concentrations, suggesting that the secondary Ca(2+) release from intracellular stores is modulated by activation of different intracellular pathways in response to low and high CCK-8 concentrations. Our experiments suggest that the propagation of Ca(2+) waves is modulated by protein kinase C (PKC) and arachidonic acid (AA). The data indicate that h.a. CCK-R are linked to phospholipase C (PLC) and phospholipase A(2) (PLA(2)) cascades, whereas l.a.CCK-R are coupled to PLC and phospholipase D (PLD) cascades. The products of PLA(2) and PLD activation, AA and diacylglycerol (DAG), cause inhibition of Ca(2+) wave propagation by yet unknown mechanisms.

Agonist-stimulated pathways of calcium signaling in pancreatic acinar cells

In pancreatic acinar cells stimulation of different intracellular pathways leads to different patterns of Ca2+ signaling. Bombesin induces activation of both phosphatidylinositol 4,5-bisphosphate (PIP2)-specific phospholipase C (PLC) and phospholipase D (PLD). The latter leads to generation of diacylglycerol (DAG) in addition to that produced by activation of PIP2-PLC. Strong activation of protein kinase C (PKC) results in inhibition of Ca(2+)-induced Ca2+ release from Ca2+ pools arranged in sequence to the luminally located IP3-sensitive Ca2+ pools. Consequently the Ca2+ wave which starts in the luminal cell pole is slower in the presence of bombesin (5 microm/s) as compared to that in the presence of acetylcholine (17 microm/s) which activates PIP2-PLC but not PLD. Activation of high-affinity CCK-receptors triggers a Ca2+ wave with slow propagation (5 microm/s) due to stimulation of phospholipase A2 (PLA2) and generation of arachidonic acid, which in turn leads to inhibition of Ca(2+)-induced Ca2+ release. Low-affinity CCK-receptors are coupled to both PIP2-PLC and PLD.

Relation of leisure-time physical activity to structural and functional arterial properties of the common carotid artery in male subjects

The structure and function of central arteries are altered with advancing age. These changes comprise arterial dilation, intima-media thickening and increase in stiffness. Arterial wall hypertrophy and increased stiffness are associated with major cardiovascular disease. In contrast to this, physical activity has been found to be inversely related to the incidence of major cardiovascular disease and mortality in humans. However, conflicting data exist on the effect of physical activity on arterial stiffness and very little data about its association with structural arterial properties. We therefore investigated the association of the self-selected leisure-time physical activity (LTPA), assessed by a self-administered questionnaire, with the structure and function of the common carotid artery, examined with high-resolution ultrasound, in 51 male subjects aged between 16 and 78 years. We found that men with a higher level of LTPA (> 38.1 MET*h/week = H-LTPA) (metabolic equivalent value; 1 MET= energy expended by a person at rest, i.e. approximately 3.5 ml oxygen uptake/kg body mass or 1 kcal/kg per h) had a significantly lower arterial stiffness (P = 0.02) than men with lower levels ( < 38.1 MET*h/week = L-LTPA) (4.32+/-1.17 versus 5.75+/-1.21 x 10(6) cm(-2)). In multiple regression analyses, with several atherosclerotic risk factors as correlating variables with arterial stiffness, LTPA persisted as an independent predictor of arterial stiffness (adjusted R2=0.19) in addition to apolipoprotein B level (adjusted R2 = 0.33). The study could not, however, show an association of LTPA with reduced intima-media thickness (L-LTPA = 0.66+/-0.15 versus H-LTPA 0.66+/-0.14) or arterial dilation of diastolic diameter (L-LTPA = 6.34 + 0.64 versus H-LTPA 6.08+/-0.69). However, the positive association of LTPA with several parameters, which correlated inversely with intima-media thickness, may be taken as an indicator for a possible positive (not visible in an ultrasonic examination of the common carotid artery) effect of LTPA on the arterial wall structure.

Immunological escape mechanisms in pancreatic carcinoma

Malignancies have developed several strategies to evade immune surveillance. We have investigated pancreatic cancer cell lines and pancreatic cancer surgical specimens to evaluate possibilities of tumor escape in the Fas system, and local immune suppression. Despite Fas expression the majority of cell lines was resistant to Fas-mediated apoptosis. The Fas-associated phosphatase-1 is a strong candidate to confer Fas resistance in pancreatic cancer cells. In addition, all investigated pancreatic cancer cell lines and cancer specimens expressed Fas ligand. Fas ligand was functional in cancer cell lines as shown by coculture assays of pancreatic cancer cell lines with Jurkat cells as targets. Additional local immune suppression was demonstrated by loss of T-cell receptor/CD3-zeta chain of pancreatic cancer infiltrating T-lymphocytes. We conclude that these tumor escape mechanisms may contribute to the poor prognosis of pancreatic cancer but also represent targets for new treatment modalities.

Quality of life following radical surgical treatment of gastric carcinoma

Quality of life (QOL) in patients with gastric cancer who underwent total gastrectomy has so far not been studied using the EORTC QLQ-C30 (Quality of Life Core Questionnaire of the European Organization for Research and Treatment of Cancer) as a standardized European QOL instrument. The aim of this study was to evaluate the effect of radical procedures such as extensive lymph node resection and combined resection of adjacent organs on patients' QOL. From 1992 to 1996, 152 patients underwent total gastrectomy. All patients alive on July 1, 1996 were included in the study (77/152). For assessing QOL, the EORTC QOL questionnaire QLQ-C30 version 2.0 and a validated gastric cancer module were sent home to the patients for self-completion. The response rate was 91%. It was possible to evaluate the questionnaires of 62 patients who had undergone resection with curative intent including 13 extended gastrectomies (21%). Of the 62 resections, 50 were combined with D2 lymphadenectomy (80.6%). The global health status was not negatively influenced by D2 lymphadenectomy and extended gastrectomy. Patients with splenectomy were more affected by treatment than patients without splenectomy. Radical gastrectomy combined with D2 lymphadenectomy is the treatment of choice for gastric cancer patients, concerning not just survival but QOL as well.

[Measuring intraoperative radiation exposure of the trauma surgeon. Measuring eye, thyroid gland and hand with highly sensitive thermoluminescent detectors]

A prospective study of 24 operative procedures involving minimal invasive techniques and fluoroscopic guidance was undertaken in order to measure the radiation exposure to the primary surgeon. Radiation was monitored with the use of high sensitive thermoluminescent dosimeters. At the spots of dosimetry (eyes, thyroid gland, hand and genitals under lead apron) the dose was uniformly low and ranged from 0.6 muSv at the eyes to 259.3 muSv at the hand. The dose is determined by the duration of fluoroscopy and the amount of scattered rays, which in turn depends on the volume being x-rayed. On the basis of our results there is no likelihood of exceeding the limits of safety regulations even in a very busy operative environment, although a statistically increased incidence of thyroid cancer or a radiation-induced glaucoma is present. In vitro measurements with irradiation of a phantom resulted in the following recommendations: 1) fluoroscopy should be performed using the magnification-mechanism of the x-ray apparatus, 2) during lateral fluoroscopy the primary surgeon should be positioned close to the image intensifier. At least the surgeon should be familiar with the technique of closed reduction and instrumentation to reduce the duration of fluoroscopy which proved to be the most important factor for the amount of the radiation exposure.

Structural, functional, and hemodynamic changes of the common carotid artery with age in male subjects

Aging of the common carotid artery (CCA) is associated with different principal structural, functional, and hemodynamic changes, which are often influenced by several atherosclerotic risk factors, so that it is difficult to estimate the exclusive effect of aging on this process. Studies dealing with vascular aging of the CCA usually assess only single, dimensional, or functional parameters, although it is likely that there are interactions and probably differences between them. Moreover, regional vascular blood flow characteristics are often not taken into consideration. Therefore, the aim of the study was to assess the age-related multiparametric changes of the CCA properties with ultrasound in 69 male subjects between the ages of 16 and 75 (42.4+/-16.5 years), who were screened for the absence of major atherosclerotic risk factors or existing vascular disease. As a result, the intima media thickness (0.052 mm/10 y) and diastolic diameter (0.17 mm/10 y) increased nearly linearly with age (r=0.60, P<0.001; and r=0.46, P<0.001, respectively). The absolute diastolic/systolic diameter change diminished by 0.10 mm/10 y (r=-0. 73, P<0.001) and peak expansion velocity dropped by 0.12 cm/s per 10 years (r=-0.62, P<0.001) highly significantly with age. The peak blood flow velocity decreased continuously with age (r=-0.67, P<0. 00) by 9.3 cm/s per 10 years. According to multiple regression analysis, peak blood flow velocity seems to reflect the changes of several structural and functional parameters in one; intima-media thickness was determined by diastolic arterial diameter and age as independent variables. The data indicate that a multiparametric assessment may contribute to a better understanding of vascular aging and might be the basis for further studies to evaluate the association of atherosclerotic risk factors and/or major vascular disease with local changes in the CCA.

An integrated process for the production of toxic catechols from toxic phenols based on a designer biocatalyst

We describe the biocatalytic production of 3-phenylcatechol from 2-phenylphenol with the whole cell biocatalyst Escherichia coli JM101 (pHBP461). The recombinant produces 2-hydroxybiphenyl 3-monooxygenase, an enzyme from Pseudomonas azelaica HBP1. This enzyme introduces a hydroxyl-group at the C3-position of a variety of 2-substituted phenols, such as 2-phenylphenol. This permits the biocatalytic production of 3-substituted catechols, which are difficult to synthesize chemically. Both 2-phenylphenol and 3-phenylcatechol are highly toxic to E. coli. The toxic effects of 2-phenylphenol were minimized by feeding this substrate to the reactor at a rate slightly below the maximum biooxidation rate. As a result, the substrate concentration in the reactor remained below toxic levels during the bioconversion. The toxic product formed was removed by continuous adsorption on the solid resin Amberlite XAD-4. To this end the reaction mixture, containing the biocatalyst, was pumped continuously through an external loop with a fluidized bed of the resin. This resin efficiently and quantitatively adsorbed both 3-phenylcatechol and the remaining trace amounts of 2-phenylphenol. Consequently, the concentrations of these compounds were kept at subtoxic levels (below 100 mg L-1) and gram amounts of 3-phenylcatechol were produced with space-time yields of up to 0.39 g L-1 h-1. The product was recovered from the resin by acidic methanol elution and purified by recrystallization from n-hexane resulting in overall yields exceeding 59%. The optimized system served as a surprisingly simple and efficient integrated process, that allows the bioconversion of toxic substrates to toxic products with whole cell biocatalysts.