Microwave de-/anti-icing using the midas-technology

For aviation, a suitable alternative for currently used in-flight anti-/de-icing technologies for today's aircrafts with metal structures and future aircrafts with replaced composite structures is necessary. Intense investigations performed at FZK have been together in collaboration with aircraft manufacturers to design and develop a new avionic microwave technology for monolithic composite structures.The full system integration has been evaluated for several airplanes considering the structural and efficiency demands. The concept of this MIDAS (MIcrowave De-icing Anti-icing System) technology as well their recent results will be presented. A full system integration has been tested and is visualized in the paper.

Stabilisation of a (betaalpha)8-barrel protein designed from identical half barrels

It has been suggested that the common (betaalpha)(8)-barrel enzyme fold has evolved by the duplication and fusion of identical (betaalpha)(4)-half barrels, followed by the optimisation of their interface. In our attempts to reconstruct these events in vitro we have previously linked in tandem two copies of the C-terminal half barrel HisF-C of imidazole glycerol phosphate synthase from Thermotoga maritima and subsequently reconstituted in the fusion construct HisF-CC a salt bridge cluster present in wild-type HisF. The resulting recombinant protein HisF-C*C, which was produced in an insoluble form and unfolded with low cooperativity at moderate urea concentrations has now been stabilised and solubilised by a combination of random mutagenesis and selection in vivo. For this purpose, Escherichia coli cells were transformed with a plasmid-based gene library encoding HisF-C*C variants fused to chloramphenicol acetyltransferase (CAT). Stable and soluble variants were identified by the survival of host cells on solid medium containing high concentrations of the antibiotic. The selected HisF-C*C proteins, which were characterised in vitro in the absence of CAT, contained eight different amino acid substitutions. One of the exchanges (Y143C) stabilised HisF-C*C by the formation of an intermolecular disulfide bond. Three of the substitutions (G245R, V248M, L250Q) were located in the long loop connecting the two HisF-C copies, whose subsequent truncation from 13 to 5 residues yielded the stabilised variant HisF-C*C Delta. From the remaining substitutions, Y143H and V234M were most beneficial, and molecular dynamics simulations suggest that they strengthen the interactions between the half barrels by establishing a hydrogen-bonding network and an extensive hydrophobic cluster, respectively. By combining the loop deletion of HisF-C*C Delta with the Y143H and V234M substitutions, the variant HisF-C**C was generated. Recombinant HisF-C**C is produced in soluble form, forms a pure monomer with its tryptophan residues shielded from solvent and unfolds with similar cooperativity as HisF. Our results show that, starting from two identical and fused half barrels, few amino acid exchanges are sufficient to generate a highly stable and compact (betaalpha)(8)-barrel protein with wild-type like structural properties.

Computer simulation for ergonomic improvements in laparoscopic surgery

It is the aim of this study to reduce the stress and strain of the medical staff during laparoscopic operations, and, simultaneously, to increase the safety and efficiency of an integrated operation room (OR) by an ergonomic redesign. This was attempted by a computer simulation approach using free modelling of the OR and 3D human models (manikins). After defining ergonomically "ideal" postures, optimal solutions for key elements of an ergonomic design of the OR (position and height of the image displays, height of the OR table and the Mayo stand) could be evaluated with special regard to the different individual body size of each member of the team. These data should be useful for the development of team adapted, user friendly integrated OR suites of the future.

Ergonomic assessment of the static stress confronted by surgeons during laparoscopic cholecystectomy

BACKGROUND

Only a few reports on static strain in the spine, neck, and head of the surgeon are available, describing it as "distinctly harmful." The aim of this study was to objectively prove the static burden during laparoscopic operations. For this, new industrial software called PCMAN was used, capable of measuring and comparing the postures of the surgeon at different monitor placements.

METHODS

Two simultaneous and synchronized video recordings of laparoscopic cholecystectomies (LC) were done using miniDV digital camcorders with the cameras standing at a 90 degrees angle to each other. Twenty operations were performed using two different placements of the monitor. In 10 cases, the monitor was placed at the patient's head in the center, and in 10 cases at the left side of the patient. Using the time codes of the recordings, different steps of the operation were identified, and the duration of these measured in seconds. Very characteristic, longer lasting postures were imported to and analyzed with the software. Results of the different setups were compared to each other, and to an "ideal" comfort posture.

RESULTS

During the intermediate steps of the operations the rate of static phases is significantly higher. Measuring the typical postures of these phases the trunk and head are significantly more rotated and bent than in comfort positions. When the monitor was at the side of the patient facing the surgeon, results were closer to the comfort posture.

CONCLUSIONS

It was proven that surgeons are confronted by significant static burden during LC. The software used was able to evaluate objectively the static posture of the surgeon during series of LC. Results also confirmed that the position of monitors significantly influences the surgeon's posture. Best setups for the whole team can be achieved by adjustable multiple monitor systems.

Renal cortical calcification in syngeneic intact rats and those receiving an infrarenal thoracic aortic graft: possible etiological roles of endothelin, nitrate and minerals, and different preventive effects of long-term oral treatment with magnesium, citrate and alkali-containing preparations

Renal cortical nephrocalcinosis (C-NC) is a rare disorder of uncertain etiology. Using highly inbred (syngeneic) male Lewis rats, we describe the spontaneous occurrence of histologically detectable C-NC in sham operated control rats (Sham; n=12), its aggravation following grafting of the ascending thoracic aorta from a donor rat to the infrarenal aorta of a recipient (ATx; n=12), and differences in C-NC inhibition after 12 weeks of oral administration of magnesium (Mg), citrate and alkali. C-NC is characterized by Kossa-positive areas located in cells of the proximal tubule close to blood vessels and also, to a lesser extent, within glomeruli. After ATx there was vascular overproduction of endothelin (ET-1) but decreased production of nitrate; in renal cortical tissue there was an excess of calcium over Mg and phosphorus and oxalate over citrate. In plasma there was an increase in calcium and creatinine within the normal range. Calcification of tubular cells was eliminated by a preparation containing potassium, sodium and bases (from citrate degradation and bicarbonate) in addition to Mg. Less effective than the latter was Mg-potassium citrate and least effective, Mg citrate. The former treatment also normalized calcemia and urinary nitrate, but only incompletely suppressed ET-1 and had no significant effect on glomerular calcification or tissue and urinary oxalate. Urinary ET-1 excess appeared directly related to the cortical tissue calcium/Mg ratio, and urinary excretion of Mg, citrate and total protein appeared to be inversely related to the severity of C-NC. It was concluded that (1) the highly inbred rat is prone to precipitation of calcium phosphate in the renal cortex; (2) this type of C-NC occurs in close proximity to and within renal vascular tissue and is associated with an imbalance of vasoconstrictors and vasodilators of endothelial origin; (3) effective inhibition of C-NC can be achieved by an alkalinizing combination of Mg, potassium, sodium and citrate, underscoring its utility in the prophylaxis of pathological calcium phosphate deposition. The significance of these findings for the etiology and treatment of clinical disorders with renal and vascular calcification is uncertain and requires further investigation.

Y chromosomal short tandem repeat (STR) loci in a representative group of males living in South Württemberg: a database for application in forensic medicine

In this study, we resolved the allelic distribution of three Y chromosomal short tandem repeats (STRs), DYS19 (n=218), DYS390 (n=257) and DYS393 (n=215), in a population study of 257 unrelated men living in the area of South Wüerttemberg/Hohenzollern. In DYS19 and in DYS393, five different alleles were discovered, and in DYS390, six different alleles. Forty-nine different haplotypes were found in 202 unrelated male individuals. By investigating each of the three STR systems separately, the most powerful results were found in DYS390, with a PE (power of exclusion) of 0.74, followed by DYS19 (PE: 0.65) and DYS393 (PE: 0.47). Using a combination of two systems (n=202), the PEs ranged from 0.79 (DYS19 and DYS393) to 0.89 (DYS19 and DYS390). The combination of all three STR systems revealed a PE of 0.93.

Linker insertion mutagenesis based on IS21 transposition: isolation of an AMP-insensitive variant of catabolic ornithine carbamoyltransferase from Pseudomonas aeruginosa

The bacterial insertion sequence IS21 when repeated in tandem efficiently promotes non-replicative cointegrate formation in Escherichia coli. An IS21-IS21 junction region which had been engineered to contain unique SalI and BglII sites close to the IS21 termini was not affected in the ability to form cointegrates with target plasmids. Based on this finding, a novel procedure of random linker insertion mutagenesis was devised. Suicide plasmids containing the engineered junction region (pME5 and pME6) formed cointegrates with target plasmids in an E.coli host strain expressing the IS21 transposition proteins in trans. Cointegrates were resolved in vitro by restriction with SalI or BglII and ligation; thus, insertions of four or 11 codons, respectively, were created in the target DNA, practically at random. The cloned Pseudomonas aeruginosa arcB gene encoding catabolic ornithine carbamoyltransferase was used as a target. Of 20 different four-codon insertions in arcB, 11 inactivated the enzyme. Among the remaining nine insertion mutants which retained enzyme activity, three enzyme variants had reduced affinity for the substrate ornithine and one had lost recognition of the allosteric activator AMP. The linker insertions obtained illustrate the usefulness of the method in the analysis of structure-function relationships of proteins.

The euthanasia debate

Nurses are key players in determining outcomes for nursing and patient care. They treat patients with actual or potential health problems, act as advocates, and educate patients and families. This makes them eminently qualified to become active participants in the debate as to the legalization of euthanasia.

Suppression of Raf-1 kinase activity and MAP kinase signalling by RKIP

Raf-1 phosphorylates and activates MEK-1, a kinase that activates the extracellular signal regulated kinases (ERK). This kinase cascade controls the proliferation and differentiation of different cell types. Here we describe a Raf-1-interacting protein, isolated using a yeast two-hybrid screen. This protein inhibits the phosphorylation and activation of MEK by Raf-1 and is designated RKIP (Raf kinase inhibitor protein). In vitro, RKIP binds to Raf-1, MEK and ERK, but not to Ras. RKIP co-immunoprecipitates with Raf-1 and MEK from cell lysates and colocalizes with Raf-1 when examined by confocal microscopy. RKIP is not a substrate for Raf-1 or MEK, but competitively disrupts the interaction between these kinases. RKIP overexpression interferes with the activation of MEK and ERK, induction of AP-1-dependent reporter genes and transformation elicited by an oncogenically activated Raf-1 kinase. Downregulation of endogenous RKIP by expression of antisense RNA or antibody microinjection induces the activation of MEK-, ERK- and AP-1-dependent transcription. RKIP represents a new class of protein-kinase-inhibitor protein that regulates the activity of the Raf/MEK/ERK module.

Cointegrase, a naturally occurring, truncated form of IS21 transposase, catalyzes replicon fusion rather than simple insertion of IS21

The bacterial insertion sequence IS21 contains two genes, istA and istB, which are organized as an operon. IS21 spontaneously forms tandem repeats designated (IS21)2. Plasmids carrying (IS21)2 react efficiently with other replicons, producing cointegrates via a cut-and-paste mechanism. Here we show that transposition of a single IS21 element (simple insertion) and cointegrate formation involving (IS21)2 result from two distinct non-replicative pathways, which are essentially due to two differentiated IstA proteins, transposase and cointegrase. In Escherichia coli, transposase was characterized as the full-length, 46 kDa product of the istA gene, whereas the 45 kDa cointegrase was expressed, in-frame, from a natural internal translation start of istA. The istB gene, which could be experimentally disconnected from istA, provided a helper protein that strongly stimulated the transposase and cointegrase-driven reactions. Site-directed mutagenesis was used to express either cointegrase or transposase from the istA gene. Cointegrase promoted replicon fusion at high frequencies by acting on IS21 ends which were linked by 2, 3, or 4 bp junction sequences in (IS21)2. By contrast, cointegrase poorly catalyzed simple insertion of IS21 elements. Transposase had intermediate, uniform activity in both pathways. The ability of transposase to synapse two widely spaced IS21 ends may reside in the eight N-terminal amino acid residues which are absent from cointegrase. Given the 2 or 3 bp spacing in naturally occurring IS21 tandems and the specialization of cointegrase, the fulminant spread of IS21 via cointegration can now be understood.

Occupational risk of Mycobacterium tuberculosis infection in hospital workers

We conducted a 4-year (1/89-12/92) retrospective cohort study among employees at a large metropolitan hospital where a nosocomial outbreak of multidrug-resistant tuberculosis (TB) had occurred. We compared the risk of tuberculin skin test (TST) conversion among employees who worked on wards where patients with culture-confirmed TB were cared for ("exposed") with the risk among employees who worked on wards with no such patients ("unexposed"). Exposed employees had a higher 4-year risk of TST conversion (14.5%) than unexposed employees (1.4%) (adjusted relative risk 13.4; 95 percent confidence interval 5.1-35.2). Exposed employees had significantly higher risks of conversion than unexposed employees during 1989-91, but not for 1992. Among the exposed, ward clerks had a risk of conversion (15.6%) only slightly lower than nurses (18.2%). We conclude that employees who worked in areas where patients with active M. tuberculosis infection were cared for, including workers who did not provide direct patient care, had a higher risk of TST conversion than employees who did not work in these areas. Reasons for the decline in risk over time include outbreak termination, fewer admissions of patients with TB, implementation of effective infection control measures, and possible resistance to infection in some members of the study population.

The prevalence of pulmonary and upper respiratory tract symptoms and spirometric test findings among newspaper pressroom workers exposed to solvents

To investigate the relationship between exposure to organic solvents and the presence of pulmonary and upper respiratory tract mucous membrane symptoms, we conducted a cross-sectional study of 215 newspaper pressroom workers who were occupationally exposed to organic solvent and lubricant mixtures. Thirty-four compositors, who were not occupationally exposed to the solvents or lubricants, served as controls. Pressroom workers and compositors underwent spirometric testing and were also asked about the presence of cough, phlegm, hemoptysis, dyspnea, wheezing, chest tightness, nose or throat irritation, eye irritation, and sinus trouble. The spirometric results did not significantly differ between the two groups. However, the pressroom workers were significantly more likely to report pulmonary or upper respiratory tract mucous membrane symptoms than were compositors (P < 0.005). An exposure-response relationship could be demonstrated when comparing the number of solvents exposed with the total number of symptoms (P < 0.001). Similarly, an exposure-response relationship could be demonstrated when comparing the frequency of use of each of the seven solvents with the total number of symptoms (P < 0.002). Each of these findings was supported in a multivariable linear regression model that adjusted for potential confounders such as age, smoking history, and number of years in the industry. A high prevalence of these symptoms was reported even though the degree of exposure to solvents and lubricants was within the current permissible exposure limits.

Negative regulation of Raf-1 by phosphorylation of serine 621

The elevation of cyclic AMP (cAMP) levels in the cell downregulates the activity of the Raf-1 kinase. It has been suggested that this effect is due to the activation of cAMP-dependent protein kinase (PKA), which can directly phosphorylate Raf-1 in vitro. In this study, we confirmed this hypothesis by coexpressing Raf-1 with the constitutively active catalytic subunit of PKA, which could fully reproduce the inhibition previously achieved by cAMP. PKA-phosphorylated Raf-1 exhibits a reduced affinity for GTP-loaded Ras as well as impaired catalytic activity. As the binding to GTP-loaded Ras induces Raf-1 activation in the cell, we examined which mechanism is required for PKA-mediated Raf-1 inhibition in vivo. A Raf-1 point mutant (RafR89L), which is unable to bind Ras, as well as the isolated Raf-1 kinase domain were still fully susceptible to inhibition by PKA, demonstrating that the phosphorylation of the Raf-1 kinase suffices for inhibition. By the use of mass spectroscopy and point mutants, PKA phosphorylation site was mapped to a single site in the Raf-1 kinase domain, serine 621. Replacement of serine 621 by alanine or cysteine or destruction of the PKA consensus motif by changing arginine 618 resulted in the loss of catalytic activity. Notably, a mutation of serine 619 to alanine did not significantly affect kinase activity or regulation by activators or PKA. Changing serine 621 to aspartic acid yielded a Raf-1 protein which, when expressed to high levels in Sf-9 insect cells, retained a very low inducible kinase activity that was resistant to PKA downregulation. The purified Raf-1 kinase domain displayed slow autophosphorylation of serine 621, which correlated with a decrease in catalytic function. The Raf-1 kinase domain activated by tyrosine phosphorylation could be downregulated by PKA. Specific removal of the phosphate residue at serine 621 reactivated the catalytic activity. These results are most consistent with a dual role of serine 621. On the one hand, serine 621 appears essential for catalytic activity; on the other hand, it serves as a phosphorylation site which confers negative regulation.

Protein kinase C-zeta reverts v-raf transformation of NIH-3T3 cells

We have identified protein kinase C-zeta (PKC-zeta) as a novel suppressor of neoplastic transformation caused by the v-raf oncogene. PKC-zeta overexpression drastically retards proliferation, abolishes anchorage-independent growth, and reverts the morphological transformation of v-raf-transformed NIH-3T3 cells. The molecular basis for this effect appears to be a specific induction of junB and egr-1 expression, triggered synergistically by PKC-zeta via a Raf/Mek/MAPK-independent mechanism and v-raf. junB-promoter/CAT assays revealed that PKC-zeta directly targets the junB promoter. The induction of junB and egr-1 is linked to the v-raf transformation-suppressing effect of PKC-zeta as constitutive expression of junB and egr-1 but not of c-jun also abolishes anchorage-independent growth of v-raf-transformed NIH-3T3 cells. Moreover, junB overexpression leads to a retardation of proliferation in these cells. PKC-zeta interferes with the serum inducibility of an AP-1 reporter plasmid in v-raf-transformed NIH-3T3 cells, indicating that PKC-zeta antagonizes transformation and proliferation by down-modulating AP-1 function via induction of junB. In summary, our data suggest that PKC-zeta counteracts v-raf transformation by modulating the expression of the transcription factors junB and egr-1.

Characterization of IkappaB kinases. IkappaB-alpha is not phosphorylated by Raf-1 or protein kinase C isozymes, but is a casein kinase II substrate

The NF-kappaB transcription factor is activated by a wide variety of stimuli, including phorbol esters such as 12-O-tetradecanoylphorbol-13-acetate. In its inactive state, NF-kappaB is sequestered in the cytoplasm tethered to an inhibitor protein, IkappaB. Activation comprises the rapid phosphorylation of IkappaB-alpha at N-terminal sites, which presumably marks IkappaB-alpha for proteolytic degradation and leads to release of NF-kappaB into the nucleus. In addition, IkappaB-alpha is constitutively phosphorylated at the C terminus, which may be a prerequisite for proper IkappaB function. Protein kinase C (PKC) is activated by 12-O-tetradecanoylphorbol-13-acetate and has been previously reported to phosphorylate IkappaB-alpha in vitro. As PKC has turned out to constitute a multigene family encoding isozymes with different biological functions, we have reinvestigated IkappaB-alpha phosphorylation by PKC using recombinant PKC isozymes expressed in insect cells. While crude PKC preparations were efficient IkappaB-alpha kinases, highly purified PKC isozymes completely failed to phosphorylate IkappaB-alpha. Biochemical separation of porcine spleen yielded at least two fractions with IkappaB-alpha kinase activity, both of which were devoid of detectable PKC isozymes. One peak contained both Raf-1 and casein kinase II (CKII). Purified Raf-1 does not phosphorylate IkappaB-alpha directly, but associates with CKII, which efficiently phosphorylates the C terminus of IkappaB-alpha. Two-dimensional phosphopeptide mapping and high pressure liquid chromatography-mass spectroscopy analysis showed that all IkappaB-alpha kinases induced phosphorylation at the same prominent sites in the C terminus. Our results clearly indicate that PKC isozymes alpha, beta, gamma, delta, epsilon, eta, and zeta as well as Raf-1 are not IkappaB-alpha kinases. They furthermore demonstrate that IkappaB-alpha is targeted by several kinases, one of which appears to be CKII.

Occupational skin disease in newspaper pressroom workers

Studies of printing industry tradespeople have reported an increased problem of dermatologic abnormalities, including contact dermatitis and dermatitis attributed to solvent exposure. The current cross-sectional health survey of dermatological conditions were conducted in a follow-up of perceived skin abnormalities among newspaper pressroom workers. We surveyed 215 pressroom workers and 34 compositors at a large northeastern US newspaper printing facility. Our findings indicate that printing pressroom workers reported skin condition symptoms at a significantly higher rate than did the compositor referent group. Pressroom workers also were found to be at a significantly elevated risk of developing dermatitis after self-reported exposure to certain commonly used solvents. This emphasizes the need for proper work practices, product substitution where possible, and appropriate protective glove use by newspaper pressroom workers.

The presence of urinary cellular sediment and albuminuria in newspaper pressworkers exposed to solvents

To investigate the relationship between exposure to organic solvents and the presence of increased urinary cellular sediment, we conducted a cross-sectional study of 215 newspaper pressroom workers who were exposed to solvent and lubricant mixtures. Thirty-two compositors were surveyed as referents. Industrial hygiene measurements showed low-level airborne exposures to organic solvents (primarily naphthas) and minimal airborne exposure to glycol ethers. There was a high prevalence of solvent-related dermatitis indicating there was significant dermal exposure to these substances. Pressworkers were exposed to solvent mixtures that were associated with dose-related increases in leukocyturia alone or in urinary cellular sediment (erythrocyturia and/or leukocyturia). The presence of urinary cellular sediment was associated with increasing frequency of use of five particular organic solvent mixtures. These results suggest that the increase in urinary cellular sediment may be due, at least in part, to the effects of solvents on the kidney. Consistent with this hypothesis, 16% of pressmen and no compositors were found to have primarily low-grade albuminuria detectable by dipstick. Workers with urinary cellular sediment were significantly more likely to have detectable albuminuria. Albuminuria was more likely to occur with increased frequency of use of four particular solvent mixtures. The presence of urinary cellular sediment was less likely to occur with occasional use of analgesics suggesting a possible etiologic role for acute or chronic urinary tract inflammation.