Sex disparities in popliteal artery aneurysms

OBJECTIVE

Only 5% of patients with popliteal artery aneurysms (PAAs) are female. Evidence on PAA treatment and outcomes in women is therefore scarce. The POPART Registry provides one of Europe's largest data collections regarding PAA treatment. Data on clinical presentation, aneurysm morphology, and perioperative outcomes after open surgical PAA repair in women will be presented.

METHODS

POPART is a multicenter, noninterventional registry for open and endovascular PAA repair, with 42 participating centers in Germany and Luxembourg. All patients aged >18 years who have been treated for PAA since 2010 are eligible for study inclusion. Data collection is based on an online electronic case report form.

RESULTS

Of the 1236 PAAs, 58 (4.8%) were in women. There were no significant differences in age or cardiopulmonary comorbidities. However, female patients had a lower prevalence of contralateral PAAs and abdominal aortic aneurysms (P < .05). PAAs in women were more likely to be symptomatic before surgery (65.5% vs 49.4%; P = .017), with 19% of women presenting with acute limb ischemia (vs 11%; P = .067). Women had smaller aneurysm diameters than men (22.5 mm vs 27 mm; P = .004) and became symptomatic at smaller diameters (20 mm vs 26 mm; P = .002). Only 8.6% of women and 11.6% of men underwent endovascular aneurysm repair (P > .05); therefore, the perioperative outcome analysis focused on open surgical repair. In total, 23.5% of women and 16.9% of men developed perioperative complications (P > .05). There were no differences in major cardiovascular events (P > .05), but women showed a higher incidence of impaired wound healing (15.7% vs 7.2%; P = .05) and major amputation (5.9% vs 1.1%; P = .027). Female sex was significantly associated with the need for nonvascular reinterventions within 30 days after surgery (odds ratio: 2.48, 95% confidence interval: 1.26-4.88), whereas no significant differences in the odds for vascular reinterventions were observed (odds ratio: 1.98, 95% confidence interval: 0.68-5.77). In the multiple logistic regression model, female sex, symptomatic PAAs, poor quality of outflow vessels, and graft material other than vein graft were independently associated with perioperative reinterventions.

CONCLUSIONS

Women have smaller PAAs, are more likely to be symptomatic before treatment, and are more often affected by nonvascular reinterventions in the perioperative course. As our understanding of aneurysmatic diseases in women continues to expand, sex-specific treatment strategies and screening options for women in well-selected cohorts with modified screening protocols should be continuously re-evaluated.

Hardness Assessment Considering Nitrided Layers Based on Tempering Tests for Numerical Wear Prediction for Forging Processes

The nitriding of forging tools is an industrially established standard used to increase the hardness of the tool surface layer and reduce wear. However, this modification of the tool surface layer, as well as the microstructural changes that occur during this operation due to the thermo-mechanical load, cannot be considered during wear calculations with the widely used Archard wear model in the context of FE simulations. Based on previous work, this study further develops two tempering tests for the investigation of the hardness evolution of two nitride profiles based on H11 tool steel. Here, significant tempering effects could be observed depending on temperature, mechanical stress superposition and time. The results are used for setting up a new material model that is implemented in an existing numerical wear model. The validation is carried out in two laboratory forging test series. The evaluation shows that the hardness development in terms of tempering effects of a nitrided forging tool can be numerically predicted, especially for high forging cycles. However, due to the unexpected occurrence of adhesion effects, only limited applicability of the wear prediction then carried out is achieved.

Clinical implications of fracture-associated vascular damage in extremity and pelvic trauma

BACKGROUND

Vascular damage in polytrauma patients is associated with high mortality and morbidity. Therefore, specific clinical implications of vascular damage with fractures in major trauma patients are reassessed.

METHODS

This comprehensive nine-year retrospective single center cohort study analyzed demography, laboratory, treatment and outcome data from 3689 patients, 64 patients with fracture-associated vascular injuries were identified and were compared to a control group.

RESULTS

Vascular damage occurred in 7% of patients with upper and lower limb and pelvic fractures admitted to the trauma room. Overall survival was 80% in pelvic fracture and 97% in extremity fracture patients and comparable to non-vascular trauma patients. Additional arterial damage required substantial fluid administration and was visible as significantly anemia and disturbed coagulation tests upon admission. Open procedures were done in over 80% of peripheral extremity vascular damage. Endovascular procedures were predominant (87%) in pelvic injury.

CONCLUSION

Vascular damage is associated with high mortality rates especially in combination with pelvic fractures. Initial anemia, disturbed coagulation tests and the need for extensive pre-clinical fluid substitution were observed in the cohort with vascular damage. Therefore, fast diagnosis and early interventional and surgical procedures are necessary to optimize patient-specific outcome.

Isotopic effects in vibrational relaxation dynamics of H on a Si(100) surface

In a recent paper [U. Lorenz and P. Saalfrank, Chem. Phys. 482, 69 (2017)], we proposed a robust scheme to set up a system-bath model Hamiltonian, describing the coupling of adsorbate vibrations (system) to surface phonons (bath), from first principles. The method is based on an embedded cluster approach, using orthogonal coordinates for system and bath modes, and an anharmonic phononic expansion of the system-bath interaction up to second order. In this contribution, we use this model Hamiltonian to calculate vibrational relaxation rates of H-Si and D-Si bending modes, coupled to a fully H(D)-covered Si(100)-(2×1) surface, at zero temperature. The D-Si bending mode has an anharmonic frequency lying inside the bath frequency spectrum, whereas the H-Si bending mode frequency is outside the bath Debye band. Therefore, in the present calculations, we only take into account one-phonon system-bath couplings for the D-Si system and both one- and two-phonon interaction terms in the case of H-Si. The computation of vibrational lifetimes is performed with two different approaches, namely, Fermi's golden rule, and a generalized Bixon-Jortner model built in a restricted vibrational space of the adsorbate-surface zeroth-order Hamiltonian. For D-Si, the Bixon-Jortner Hamiltonian can be solved by exact diagonalization, serving as a benchmark, whereas for H-Si, an iterative scheme based on the recursive residue generation method is applied, with excellent convergence properties. We found that the lifetimes obtained with perturbation theory, albeit having almost the same order of magnitude-a few hundred fs for D-Si and a couple of ps for H-Si-, are strongly dependent on the discretized numerical representation of the bath spectral density. On the other hand, the Bixon-Jortner model is free of such numerical deficiencies, therefore providing better estimates of vibrational relaxation rates, at a very low computational cost. The results obtained with this model clearly show a net exponential decay of the time-dependent survival probability for the H-Si initial vibrational state, allowing an easy extraction of the bending mode "lifetime." This is in contrast with the D-Si system, whose survival probability exhibits a non-monotonic decay, making it difficult to define such a lifetime. This different behavior of the vibrational decay is rationalized in terms of the power spectrum of the adsorbate-surface system. In the case of D-Si, it consists of several, non-uniformly distributed peaks around the bending mode frequency, whereas the H-Si spectrum exhibits a single Lorentzian lineshape, whose width corresponds to the calculated lifetime. The present work gives some insight into mechanisms of vibration-phonon coupling at surfaces. It also serves as a benchmark for multidimensional system-bath quantum dynamics, for comparison with approximate schemes such as reduced, open-system density matrix theory (where the bath is traced out and a Liouville-von Neumann equation is solved) or approximate wavefunction methods to solve the combined system-bath Schrödinger equation.

Erratum: Hanbury Brown-Twiss Interferometry at a Free-Electron Laser [Phys. Rev. Lett. 111, 034802 (2013)]

This corrects the article DOI: 10.1103/PhysRevLett.111.034802.

Revealing Three-Dimensional Structure of an Individual Colloidal Crystal Grain by Coherent X-Ray Diffractive Imaging

We present results of a coherent x-ray diffractive imaging experiment performed on a single colloidal crystal grain. The full three-dimensional (3D) reciprocal space map measured by an azimuthal rotational scan contained several orders of Bragg reflections together with the coherent interference signal between them. Applying the iterative phase retrieval approach, the 3D structure of the crystal grain was reconstructed and positions of individual colloidal particles were resolved. As a result, an exact stacking sequence of hexagonal close-packed layers including planar and linear defects were identified.

Inhibition of Human Immunodeficiency Virus Type 1 Reverse Transcriptase by Degradation Products of Ceftazidime

Previous work by Hafkemeyer et al. (1991) [ Nucleic Acids Research19: 4059–4065] indicated that a degradation product of ceftazidime, termed HP 0.35, was active against the RNase H activity of human immunodeficiency virus type 1 (HIV-1) and feline immunodeficiency virus (FIV) reverse transcriptase (RT) in vitro. Attempting to repeat these results, we isolated HP 0.35 from an aqueous degradation of ceftazidime and, after careful purification, we found HP 0.35 to be essentially inactive against both the polymerase and RNase H domains of HIV-1 RT (IC50 of >100 μg mL−1). During the investigation we discovered that polymeric degradation products of ceftazidime inhibited both the polymerase and, to a greater extent, the RNase H activities of HIV-1 RT in vitro (IC50 approximately 0.1 and 0.01 μg mL−1, respectively). Subjecting HP 0.35 to conditions under which it could polymerize induced inhibitory activity similar to that of the polymeric ceftazidime degradation products. It is proposed that the previously reported activity of HP 0.35 may have resulted from the presence of low levels of polymeric material either from incomplete purification or from polymerization of HP 0.35 during storage or in vitro testing.

Theoretical study of electronic damage in single-particle imaging experiments at x-ray free-electron lasers for pulse durations from 0.1 to 10 fs

X-ray free-electron lasers (XFELs) may allow us to employ the single-particle imaging (SPI) method to determine the structure of macromolecules that do not form stable crystals. Ultrashort pulses of 10 fs and less allow us to outrun complete disintegration by Coulomb explosion and minimize radiation damage due to nuclear motion, but electronic damage is still present. The major contribution to the electronic damage comes from the plasma generated in the sample that is strongly dependent on the amount of Auger ionization. Since the Auger process has a characteristic time scale on the order of femtoseconds, one may expect that its contribution will be significantly reduced for attosecond pulses. Here we study the effect of electronic damage on the SPI at pulse durations from 0.1 to 10 fs and in a large range of XFEL fluences to determine optimal conditions for imaging of biological samples. We analyzed the contribution of different electronic excitation processes and found that at fluences higher than 10(13)-10(15) photons/μm(2) (depending on the photon energy and pulse duration) the diffracted signal saturates and does not increase further. A significant gain in the signal is obtained by reducing the pulse duration from 10 to 1 fs. Pulses below a duration of 1 fs do not give a significant gain in the scattering signal in comparison with 1-fs pulses. We also study the limits imposed on SPI by Compton scattering.

Comparing thermal wave function methods for multi-configuration time-dependent Hartree simulations

We compare two methods for creating stochastic temperature wave functions that can be used for Multi-Configuration Time-Dependent Hartree (MCTDH) simulations. In the first method, the MCTDH coefficients are chosen randomly, while the other method uses a single Hartree product of random single-particle functions (SPFs). We find that using random SPFs dramatically improves convergence for a model system for surface sticking.

Intensity interferometry of single x-ray pulses from a synchrotron storage ring

We report on measurements of second-order intensity correlations at the high-brilliance storage ring PETRA III using a prototype of the newly developed adaptive gain integrating pixel detector. The detector records individual synchrotron radiation pulses with an x-ray photon energy of 14.4 keV and repetition rate of about 5 MHz. The second-order intensity correlation function is measured simultaneously at different spatial separations, which allows us to determine the transverse coherence length at these x-ray energies. The measured values are in a good agreement with theoretical simulations based on the Gaussian Schell model.

Double hexagonal close-packed structure revealed in a single colloidal crystal grain by Bragg rod analysis

A coherent X-ray diffraction study of a single colloidal crystal grain composed of silica spheres is reported. The diffraction data contain Bragg peaks and additional features in the form of Bragg rods, which are related to the stacking of the hexagonally close-packed layers. The profile of the Bragg rod shows distinct intensity modulations which, under the specific experimental conditions used here, are directly related to the stacking sequence of the layers. Using a model for the scattered intensity along the Bragg rod for an exact stacking sequence of a finite number of hexagonally close-packed layers, it is found that a double hexagonal close-packed stacking sequence is present in the colloidal crystal grain. This analysis method opens up ways to obtain crucial structural information from finite-sized crystalline samples by employing advanced third-generation X-ray sources.

In situ X-ray crystallographic study of the structural evolution of colloidal crystals upon heating

The structural evolution of colloidal crystals made of polystyrene hard spheres has been studied in situ upon incremental heating of a crystal in a temperature range below and above the glass transition temperature of polystyrene. Thin films of colloidal crystals having different particle sizes were studied in transmission geometry using a high-resolution small-angle X-ray scattering setup at the P10 Coherence Beamline of the PETRA III synchrotron facility. The transformation of colloidal crystals to a melted state has been observed in a narrow temperature interval of less than 10 K.

Hanbury Brown-Twiss interferometry at a free-electron laser

We present measurements of second- and higher-order intensity correlation functions (so-called Hanbury Brown-Twiss experiment) performed at the free-electron laser (FEL) FLASH in the non-linear regime of its operation. We demonstrate the high transverse coherence properties of the FEL beam with a degree of transverse coherence of about 80% and degeneracy parameter of the order 10(9) that makes it similar to laser sources. Intensity correlation measurements in spatial and frequency domain gave an estimate of the FEL average pulse duration of 50 fs. Our measurements of the higher-order correlation functions indicate that FEL radiation obeys Gaussian statistics, which is characteristic to chaotic sources.

Impact of ultrafast electronic damage in single-particle x-ray imaging experiments

In single-particle coherent x-ray diffraction imaging experiments, performed at x-ray free-electron lasers (XFELs), samples are exposed to intense x-ray pulses to obtain single-shot diffraction patterns. The high intensity induces electronic dynamics on the femtosecond time scale in the system, which can reduce the contrast of the obtained diffraction patterns and adds an isotropic background. We quantify the degradation of the diffraction pattern from ultrafast electronic damage by performing simulations on a biological sample exposed to x-ray pulses with different parameters. We find that the contrast is substantially reduced and the background is considerably strong only if almost all electrons are removed from their parent atoms. This happens at fluences of at least one order of magnitude larger than provided at currently available XFEL sources.

In vivo detection of Staphylococcus aureus in biofilm on vascular prostheses using non-invasive biophotonic imaging

OBJECTIVES

Biophotonic imaging was compared to standard enumeration method both for counting Staphylococcus aureus in biofilm and bacterial susceptibility tests of different graft materials.

DESIGN

Prospective, randomized, controlled animal study.

MATERIAL AND METHODS

Five types of vascular grafts were placed subcutaneously in 35 mice and challenged with bioluminescent S. aureus. The mice were divided into equal groups as follows: group A (polyester), group B (polytetrafluoroethylene), group C and D (two types of silver acetate-coated polyester) and group E (bovine pericardium). Controls were given only the bacteria. The bioluminescence signal of S. aureus, able to predict number of viable bacteria in biofilm without any manipulation, was measured at different time points. Five days postinfection, regular cultures of adherent bacteria on grafts were obtained. Comparative analyses between bioluminescence activity and culture enumeration were performed.

RESULTS

The number of viable bacteria on silver-coated prostheses was the slightest, indicating superior bacterial resistance. The density of bacteria on polytetrafluoroethylene and polyester was comparable, with a non-significant advantage for polytetrafluoroethylene. Moreover, bioluminescence detected the number of viable S. aureus in biofilm more exactly compared to enumeration of bacteria.

CONCLUSION

Bioluminescence imaging can be considered a useful tool to characterize susceptibility of any graft material to bacterial biofilm prior to implantation.

[Medium-term results of anatomic straight-shaft IMAGE implantation in primary hip joint endoprosthetics--a prospective study]

AIM

The IMAGE prosthesis was developed with the objective of proximal load induction to avoid stress shielding and proximal bone resorption. In this study patients were followed clinically and radiologically with a special emphasis on osteointegration of the shaft in the proximal and distal regions. In addition, the reconstruction of the bony geometry of the proximal humerus was investigated.

METHOD

95 consecutive patients (mean age: 61.1 years) with an IMAGE shaft were followed up prospectively over five years after primary hip arthroplasty. Radiologically, the osteointegration was appraised on the basis of the parameters cortical bone hypertrophy, radiolucent lines, shaft sintering and the position of the rotational centre. The clinical parameters assessed were the Harris hip score (HSS) and the WOMAC score.

RESULTS

In Dorr C configuration no distal cortical bone hypertrophy was visible, in contrast to 19% in types A and B. By means of this criterion in 81% of the cases, a metaphyseal anchoring can be assumed. In 20% of the cases proximal and in 11.1% distal radiolucent lines were found. In only 3.3 % of the patients were the radiolucent lines due to unwanted distal osteointegration. In most cases the reasons were PE wear and metallosis. In 18.8% a distal anchoring was visible. Sintering (in total 18 prostheses) was greatest in Dorr C configuration and high-grade osteoporosis. The difference in offset reconstruction was 4.23 mm on average. In reconstruction of the rotational centre the variability was between 2.0 and 6.9 mm. 94.13 points were attained in the HHS and 10.13 points in the WOMAC score. Specific complications related to the implantation were not observed.

CONCLUSIONS

Proximal stress transmission can be supported and the danger of stress shielding can be reduced by means of an appropriate design of a prosthetic stem. Distal corticoid hypertrophy was found in only 19% of the patients with the prosthesis model investigated as compared to 60% having prostheses with distal femoral anchoring. The medium-term clinical results are excellent, so that the shaft appears suitable for primary as well as secondary osteoarthritis of the hip joint.

Vorbeugende Behandlung des Atemnotsyndroms des Neugeborenen durch antepartale Glukokortikoidgabe (Betamethason)

Betamethason was administered to 105 patients with threatened premature labour at risk for respiratory distress syndrome (RDS) of the newborn. The most important indications were premature rupture of the membranes (30%) and premature labour (40%). The betamethason treatment was given between the 27. and 35. week of gestation. 79% of the patients delivered prior to 36 weeks of gestation, over 50% prior to 34 weeks gestation. The total incidence of RDS was 25%. Severe types of RDS (stage III and IV) were rare (7%). The mortality of RDS after betamethason treatment was 5.4%. After 32 weeks gestation the mortality from RDS was 0%. Severe types of RDS appear to occur more often in male than in female infants. The incidence of RDS was not lowered further by premature of the membranes. The lecithin/sphingomyelin(L/S)-ratio in the amniotic fluid following treatment with betamethason increased to over 2 in only 2/3 of the cases. The predictive value of the L/S ratio that respiratory distress syndrome of the newborn only occurs rarely with values over 2 was maintained after treatment with betamethason. Our rate in cases with an L/S ratio over 2 was 7.9%.

Potentiation of nociceptive responses to low pH injections in humans by prostaglandin E2

Inflammation and trauma lead to tissue acidification and release of inflammatory mediators, including prostaglandin E2 (PGE2). Protons can evoke pain through acid-sensing ion channels (ASICs) and TRPV1 receptors. In this study, we examined whether PGE2 can potentiate proton-induced nociception in humans on injection into skin and muscle. Psychophysical and vascular responses to microinjections of protons (pH 6.0 and 6.5), PGE2 (10-6 and 10-7 M) and their combinations into forearm skin (30 microL) or anterior tibial muscle (50 microL) were assessed in 16 male subjects. Pain intensity, axon reflex erythema, and heat pain thresholds were recorded after skin challenge; pain intensity and thresholds for pressure-evoked pain were recorded after intramuscular injections. Intradermal or intramuscular injections of PGE2 induced very low levels of pain similar to saline. Administration of low pH caused moderate pain within 5 seconds that declined rapidly over 15 to 20 seconds. In comparison, coinjection of low pH with PGE2 led to a biphasic profile of the pain response. Combined pH + PGE2 stimulation provoked significantly increased pain in the second phase after injections (20 to 100 seconds) both in skin and muscle, whereas the initial injection pain was not enhanced. Heat pain thresholds were reduced after PGE2 and combined pH + PGE2, whereas flare responses were rather attenuated on coadministration of low pH with PGE2. Intriguingly, when compared with skin, muscle pain was significantly lower in the initial phase (0 to 15 seconds) but significantly higher in the second phase (20 to 100 seconds after injection).

PERSPECTIVE

PGE2 can potentiate nociceptor activation by protons in human skin and muscle, indicated by increased sustained pain ratings. This can be best explained by TRPV1 sensitization in the presence of PGE2, a mechanism potentially relevant for inflammatory and injury-induced pain.

Analysis of closure of the pancreatic remnant after distal pancreatic resection

BACKGROUND

The appropriate management of the pancreatic remnant following distal pancreatic resection remains a clinically relevant problem. We carried out a retrospective analysis which focused on this issue and compared the two favored techniques of suture and staple closure.

PATIENTS AND METHODS

Forty-six patients underwent distal pancreatectomy between October 1999 and January 2006. The patients were retrospectively analysed based on the management of the remaining pancreatic gland. Thirty-seven patients had suture and nine patients had staple closure. The morbidity, mortality, incidence of pancreatic fistula, necessity of secondary surgical intervention, and the duration of hospital stay for the two groups were compared. Pancreatic fistula was considered according to the novel international standard definition (ISGPF). In addition, subgroup analysis of patients receiving octreotide was carried out.

RESULTS

Overall, postoperative morbidity due to pancreatic fistula occurred in seven patients (19%) after suture and in one patient (11%) after staple closure (p = 0.54), with no deaths. The number of patients with surgical revision related to pancreatic leakage was two (5%) after suture closure vs no revision after staple closure (p = 0.65). The median number of total hospital days for the suture group was 19 (range 7-78 days) vs 21 (range 12-96 days) for the stapler group (p = 0.21). No significant benefit for the octreotide application could be determined.

CONCLUSION

According to the data, no significant difference for either suture or stapler closure was observed, with the tendency for staple closure to be superior.

Latissimus-dorsi-Plastik zur Versorgung irreparabler Rotatorenmanschettenmassendefekte

AIM

Latissimus dorsi transfer is a difficult operation with a long rehabilitation. We investigated if it is worth the effort.

METHOD

We used this technique in 22 patients with an inoperable rotator cuff tear (15 patients had a primary surgery, 7 patients were operated after failed prior rotator cuff repair). Additional lesions were also considered in the analysis. The average follow up was 9 months. The results were divided in 4 groups: severe indication, primary reconstruction, 3-tendon rupture, secondary reconstruction.

RESULTS

The best results were achieved by the group "severe indication" (raising in the Constant score from 38 to 79 points). The group with primary surgery (increasing from 43 to 67 points) had better results than the group with failed prior reconstruction (increasing from 33 to 62 points). In case of additional rupture of the subscapularis tendon (45 to 58 points) or insufficiency of the deltoid muscle (33 to 45 points) the results are not satisfactory. The postoperative pain relief was felt as the predominant improvement.

CONCLUSION

The latissimus dorsi transfer is a valuable and safely reproducible procedure. Depending on the preoperative grade of deficiency it is possible to achieve a shoulder function of 60-90 % in comparison to the healthy shoulder. Despite the difficult operation technique and the long rehabilitation phase, the LDP is worth the effort on patients with irreparable rotator cuff tears. It is not the right procedure in cases of defect arthropathy--in these cases inverted shoulder prosthesis should be used.

Online load measurement in combined sewer systems--possibilities of an integrated management of waste water transportation and treatment

To obtain a further appreciable reduction of discharges in the area of sewage disposal, besides waste water purification at our treatment plants, discharge of wastewater through the sewer system has to be taken into account. Today, control strategies pursuing this aim are mainly based on hydraulic conditions like level or flow rate. They all neglect the wastewater organic load as an essential parameter. The main reasons are the expensive methods used to continuously measure traditional organic sum parameters like COD or TOC. A meaningful alternative to those parameters is the spectral absorption coefficient at lambda = 254 nm (SAC), defined in DIN 38402 by the German Institute for Standardisation. As a purely physical parameter, the SAC shows a good correlation to organic sum parameters like COD and TOC, especially if municipal wastewater is considered. By using an UV-process probe, it is possible to measure the SAC and infer the organic load of raw wastewater continuously without any sample pre-treatment. By the use of this instrument numerous possibilities arise, in order to control the sewers discharge load depend.

Role of the tyrosine phosphatase SHP-1 in K562 cell differentiation

The erythro-megakaryoblastic leukemia cell line K562 undergoes erythroid or myeloid differentiation in response to treatment with various inducing agents. We observed that expression of the SH2-containing protein tyrosine phosphatase SHP-1 was induced upon exposure of K562 cells to differentiating agents. Under the same conditions, expression of SHP-2, a close relative of SHP-1, and the more distantly related PTP-1 B remained unchanged. Induction of SHP-1 expression correlates with dephosphorylation of a specific and limited set of tyrosyl phosphoproteins, suggesting that dephosphorylation of these proteins may be important for the differentiation process. Importantly, expression of exogenous SHP-1 inhibits K562 proliferation and alters the adhesion properties of these cells, indicating a more differentiated phenotype. Moreover, SHP-1 is found in a complex with both p210 Bcr-Abl and p190 Bcr-Abl, suggesting that it may regulate Bcr-Abl or Bcr-Abl-associated phosphotyrosyl proteins. Our results indicate that induction of SHP-1 expression is important for K562 differentiation in response to various inducers and raise the possibility that functional inactivation of SHP-1 may play a role in progression to blast crisis in chronic myelogenous leukemia.

Butterfly wing pattern mutants: developmental heterochrony and co-ordinately regulated phenotypes

Butterfly wings are colored late in development, when pigments are synthesized in specialized wing scale cells in a fixed developmental succession. In this succession, colored pigments are deposited first and the remaining areas are later melanized black or brown. Here we studied the developmental changes underlying two wing pattern mutants, firstly melanic mutants of the swallowtail Papilio glaucus, in which the yellow background is turned black, and secondly a Spotty mutant of the satyrid Bicyclus anynana, which carries two additional eyespots. Despite the very different pattern changes in these two mutants, they are both associated with changes in rates of scale development and correspondingly, the final color pattern. In the melanic swallowtail, background scales originally destined to become yellow (normally developing early and synthesizing papiliochrome) show delayed development, fail to make papiliochrome, and subsequently melanize at the same time as scales in the wild-type black pattern. In the B. anynana eyespot, scale maturation begins with the central white focus, then progresses to the surrounding gold ring and later finishes with melanization of the black center. Mutants showing additional eyespots display accelerated rates of scale development (corresponding to new eyespots) in wing cells not normally occupied by eyespots. Thus by either delaying or accelerating rates of scale development, the final color, or position, of a wing pattern element can be changed. We propose that this heterochrony of scale development is a basic mechanism of color pattern formation on which developmental mutants act to change lepidopteran color patterns.

Human antibody response during sepsis against targets expressed by methicillin resistant Staphylococcus aureus

The identification of target structures is a prerequisite for the development of new treatment options, like antibody based therapy, against methicillin resistant Staphylococcus aureus (MRSA). In this study we identified immunodominant structures which were expressed in vivo during sepsis caused by MRSA. Using human sera we compared the immune response of humans with MRSA sepsis with the immune response of normal individuals and asymptomatically colonized individuals. We identified and characterized four staphylococcal specific antigenic structures. One target is a staphylococcal protein of 29 kDa that exhibited 29% identity to secreted protein SceA precursor of Staphylococcus carnosus. The putative function of this protein, which was designated IsaA (immunodominant staphylococcal antigen), is unknown. The second target is an immunodominant protein of 17 kDa that showed no homology to any currently known protein. This immunodominant protein was designated IsaB. The third and fourth antigens are both immunodominant proteins of 10 kDa. One of these proteins showed 100% identity to major cold shock protein CspA of S. aureus and the other protein was identified as the phosphocarrier protein Hpr of S. aureus. The identified immunodominant proteins may serve as potential targets for the development of antibody based therapy against MRSA.

The tyrosine phosphatase SHP-1 influences thymocyte selection by setting TCR signaling thresholds

Modulation of the strength of signals from the TCR determines the outcome of positive and negative selection in thymocyte development. Previous studies have demonstrated that SHP-1 plays a role in determining signal strength from the TCR. Here, we have taken a genetic approach to test whether SHP-1 plays a role in T cell selection in the thymus. Experiments in which a dominant negative mutant of SHP-1 was expressed in the BYDP hybridoma cell line confirmed that SHP-1 regulated TCR signaling in a cell-autonomous manner and suggested that Lck is one of its targets. To examine the role of SHP-1 in T cell development, we crossed the ovalbumin-specific DO11.10 TCR transgene onto the motheaten background, which lacks SHP-1 expression. Analysis of the progeny of these crosses provided evidence that SHP-1 regulates thymocyte selection: (i) flow cytometric analyses revealed alterations in the percentages of thymocyte subpopulations in the me/me background; (ii) ex vivo deletion experiments demonstrated that me/me:Tg thymocytes undergo negative selection at lower concentrations of OVA peptide compared to +/+:Tg thymocytes; and (iii) ex vivo proliferation analyses indicated that me/me:Tg thymocytes were hyper-sensitive to stimulation by the specific OVA peptide. Our observation that the absence of SHP-1 leads to altered selection of TCR transgenic thymocytes demonstrates that SHP-1 regulates the strength of TCR-mediated signals in vivo and, in turn, helps to set the threshold for thymocyte selection.

Effect of epidermal growth factor on enzymes of phospholipid biosynthesis in lung and liver of fetal rat in vivo and in vitro

Epidermal growth factor (EGF), a mitogenic polypeptide that binds to cell surface receptors, is an important regulator of cell differentiation and fetal lung surfactant synthesis, and may be used as a potential novel therapeutic agent in prematurity. Nevertheless, the distinct role in lung development and its mechanisms of action are not well understood. We investigated in vivo the systemic effect of intrafetally administered EGF (200 ng/g fetal body weight) and maternally administered dexamethasone (DEXA; 0.2 and 2.0mg/kg maternal body weight) on the activity of important enzymes of the phospholipid synthesis in the fetal rat lung and liver: choline kinase (EC 2.7.1.32), cholinephosphate cytidyltransferase (EC 2.7.7.15), choline phosphotransferase (EC 2.7.8.2), lysolecithin acyltransferase (EC 2.3.1.23) and glycerolphosphate phosphatidyltransferase (EC 2.7.8.5). Additionally, in vivo and in vitro effects of DEXA on EGF receptor synthesis, and the effects of EGF on protein content and morphogenesis of the fetal rat lung organoid culture, were evaluated. Whereas DEXA induced the activity of all investigated enzymes of phospholipid synthesis and increased EGF receptor synthesis, EGF has no effects on the enzymes, either in vivo or in vitro. EGF enhanced protein synthesis and morphogenesis in vitro. With respect to our data and the literature, we hypothesize that DEXA and EGF may act on different cellular sides. Whereas glucocorticoids induce surfactant phospholipid synthesis, EGF should be more involved in cell proliferation and morphogenesis.

Discordant effects of activator protein-1 transcription factor on gene regulation, invasion, and metastasis in spontaneous, radiation-induced, and fos-induced osteosarcomas

Bone cells are a prime target for the biological function of the fos/jun (activating protein-1 (AP-1)) transcription factor complex. Deregulated expression of c-fos or v-fos in bone cells induces tumorigenicity and the formation of non-metastatic osteosarcomas. In contrast, fos oncogenes transform fibroblasts to an invasive phenotype accompanied by the expression of various invasion- and metastasis-associated genes. Here we compared the expression of AP-1-dependent genes and AP-1 activity in cell lines from fos-induced, radiation-induced, and spontaneous osteosarcomas. We showed that the presence of high AP-1 activity was not sufficient for the induction of invasion- and metastasis-associated AP-1-dependent genes in transformed bone cells. Further, we identified the collagenase I and stromelysin 1 gene promoters as suitable tools for the analysis of other factors regulating metastatic progression of osteosarcoma.

Changes in mineral composition of rabbit corneas after alkali burn

BACKGROUND

Mineral balance is essential for maintaining corneal transparency. In preliminary investigations, we found alterations of mineral concentrations in the human cornea after chemical burns. In this prospective study the mineral content of the rabbit cornea was quantified after experimental alkali burns.

METHODS

Thirty-two eyes of rabbits were burnt for 30 s with 1 M NaOH. A short period of saline rinsing followed, but no further therapy was given. The eyes of 20 healthy rabbits served as a control. We measured the water content by weighing the cornea before and after drying. The mineral content of the cornea was determined in different stromal layers using energy-dispersive X-ray analysis in the scanning electron microscope. Groups of eight rabbits were examined on days 0, 1, 4 and 8 after the experimental burns.

RESULTS

After alkali burns the mineral composition of the corneal stroma changed considerably. Sodium was present in high concentrations immediately after burning, up to 708 mmol/kg dry weight, and returned to normal on day eight. Chlorine increased significantly throughout the whole period. Sulphur concentrations stayed almost normal, showing only a minute loss of ground substance after alkali burn. A considerable and increasing edema could be concluded from the water content.

CONCLUSIONS

Alkali burns resulted in a dramatic change of the corneal mineral content. Therapeutic intervention with appropriate solutions is required to restore and maintain the normal mineral composition of the denuded corneal stroma.

Lack of SHPTP1 results in src-family kinase hyperactivation and thymocyte hyperresponsiveness

Protein tyrosine phosphorylation and dephosphorylation are key regulatory events in T-cell receptor (TCR) signaling. We investigated the role of the tyrosine phosphatase SHPTP1 in TCR signaling by analysis of TCR signal transduction in motheaten (me/me) mice, which lack SHPTP1 expression. As revealed by flow cytometric analysis, thymocyte development was normal in me/me mice. However, me/me thymocytes hyperproliferated (3-to 5-fold) in response to TCR stimulation, whereas their response to interleukin 2 stimulation was unchanged compared with normal thymocytes. TCR-induced hyperproliferation of me/me thymocytes was reproduced in purified single-positive thymocytes. Moreover, me/me thymocytes produced increased amounts of interleukin 2 production upon TCR stimulation. Biochemical analysis revealed that, in response to TCR or TCR/CD4 stimulation, thymocytes lacking SHPTP1 showed increased tyrosyl phosphorylation of several cellular substrates, which correlated with increased activation of the src-family kinases Lck and Fyn. Taken together, our data suggest that SHPTP1 is an important negative regulator of TCR signaling, acting at least in part to inactivate Lck and Fyn.

Genetic analysis reveals cell type-specific regulation of receptor tyrosine kinase c-Kit by the protein tyrosine phosphatase SHP1

Receptor protein tyrosine kinases (RTKs) transmit downstream signals via interactions with secondary signaling molecules containing SH2 domains. Although many SH2-phosphotyrosyl interactions have been defined in vitro, little is known about the physiological significance of specific RTK/SH2 interactions in vivo. Also, little is known about the mechanisms by which specific RTKs interact with and/or are regulated by specific protein tyrosine phosphatases (PTPs). To address such issue, we carried out a genetic analysis of the previously reported biochemical interaction between the RTK c-Kit, encoded at the W locus, and the SH2-containing non-transmembrane PTP SHP1, encoded at the motheaten (me) locus (1). Mice carrying a kinase-defective allele of c-Kit (Wv/+) were crossed with me/+ mice, which carry one effectively null allele of SHP1, and then backcrossed to generate all possible allelic combinations. Our results indicate strong intergenic complementation between these loci in hematopoietic progenitor cells. Compared to progenitors purified from normal mice, bone marrow progenitor cells (lin-) from me/me mice markedly hyper-proliferated in response to Kit ligand (KL). stimulation. Superimposition of the me/me genotype increased the number of one marrow-derived CFU-E from Wv/+ mice. Conversely, the presence of one or two copies of Wv decreased the number of macrophages and granulocytes in me/me lung, skin, peripheral blood and bone marrow, thereby decreasing the severity of the me/me phenotype. The decrease in dermal mast cells in Wv/Wv mice was rescued to levels found in Wv/+mice by superimposition of the me/me genotype. Surprisingly, however, the presence or absence of SHP1 had no effect on the proliferative response of bone marrow-derived cultured mast cells to KL or IL3 ex vivo. Nevertheless, the immediate-early response to KL stimulation, as measured by KL-induced tyrosyl phosphorylation, was substantially increased in mast cells from Wv/+:me/me compared to Wv/ +:+/+ mice, strongly suggesting that SHP1 directly dephosphorylates and regulates c-Kit. Taken together, our results establish that SHP1 negatively regulates signaling from c-Kit in vivo, but in a cell type-specific manner.

Specific recruitment of SH-PTP1 to the erythropoietin receptor causes inactivation of JAK2 and termination of proliferative signals

The binding of erythropoietin (EPO) to its receptor (EPO-R) activates the protein tyrosine kinase JAK2. The mechanism of JAK2 inactivation has been unclear. We show that the hematopoietic protein tyrosine phosphatase SH-PTP1 (also called HCP and PTP1C) associates via its SH2 domains with the tyrosine-phosphorylated EPO-R. In vitro binding studies suggest that Y429 in the cytoplasmic domain of the EPO-R is the binding site for SH-PTP1. Mutant EPO-Rs lacking Y429 are unable to bind SH-PTP1; cells expressing such mutants are hypersensitive to EPO and display prolonged EPO-induced autophosphorylation of JAK2. Our results suggest that activation of SH-PTP1 by binding to the EPO-R plays a major role in terminating proliferative signals.

Interaction of Shc with Grb2 regulates association of Grb2 with mSOS

The adapter protein Shc has been implicated in Ras signaling via many receptors, including the T-cell antigen receptor (TCR), B-cell antigen receptor, interleukin-2 receptor, interleukin-3 receptor, erythropoietin receptor, and insulin receptor. Moreover, transformation via polyomavirus middle T antigen is dependent on its interaction with Shc and Shc tyrosine phosphorylation. One of the mechanisms of TCR-mediated, tyrosine kinase-dependent Ras activation involves the simultaneous interaction of phosphorylated Shc with the TCR zeta chain and with a second adapter protein, Grb2. Grb2, in turn, interacts with the Ras guanine nucleotide exchange factor mSOS, thereby leading to Ras activation. Although it has been reported that in fibroblasts Grb2 and mSOS constitutively associate with each other and that growth factor stimulation does not alter the levels of Grb2:mSOS association, we show here that TCR stimulation leads to a significant increase in the levels of Grb2 associated with mSOS. This enhanced Grb2:mSOS association, which occurs through an SH3-proline-rich sequence interaction, is regulated through the SH2 domain of Grb2. The following observations support a role for Shc in regulating the Grb2:mSOS association: (i) a phosphopeptide corresponding to the sequence surrounding Tyr-317 of Shc, which displaces Shc from Grb2, abolished the enhanced association between Grb2 and mSOS; and (ii) addition of phosphorylated Shc to unactivated T cell lysates was sufficient to enhance the interaction of Grb2 with mSOS. Furthermore, using fusion proteins encoding different domains of Shc, we show that the collagen homology domain of Shc (which includes the Tyr-317 site) can mediate this effect. Thus, the Shc-mediated regulation of Grb2:mSOS association may provide a means for controlling the extent of Ras activation following receptor stimulation.

Intramolecular regulation of protein tyrosine phosphatase SH-PTP1: a new function for Src homology 2 domains

The steady-state kinetic properties of SH-PTP1 (PTP1C, SHP, HCP), a Src homology 2 (SH2) domain-containing protein tyrosine phosphatase (PTPase), were assessed and compared with those of three truncation mutants, using p-nitrophenyl phosphate, phosphotyrosyl (pY) peptides, and reduced, carboxyamido-methylated, maleylated, and tyrosyl-phosphorylated lysozyme as substrates. At physiological pH (7.4), truncation of the two N-terminal SH2 domains [SH-PTP1(delta SH2)] or the last 35 amino acids of the C-terminus [SH-PTP1(delta C35)] activated the phosphatase activity by 30-fold and 20-34-fold relative to the wild-type enzyme, respectively. Truncation of the last 60 amino acids resulted in a mutant [SH-PTP1(delta C60)] with wild-type activity. SH-PTP1 and SH-PTP1(delta C60) displayed apparent saturation kinetics toward pNPP only at acidic pH (pH < or = 5.4); as pH increased above 5.5, their apparent KM values increased dramatically. In contrast, SH-PTP1(delta SH2) obeyed normal Michaelis-Menten kinetics at all pH values tested (pH 5.1-7.4) with a constant KM (10-14 mM). Furthermore, two synthetic pY peptides corresponding to known and potential phosphorylation sites on the erythropoietin (EPOR pY429) and interleukin-3 (IL-3R pY628) receptors bound specifically to the N-terminal SH2 domain of SH-PTP1 (KD = 1.8-10 microM) and activated the catalytic activity of SH-PTP1 and SH-PTP1(delta C60) but not SH-PTP1(delta SH2), in a concentration-dependent manner. Maximal activation (25-30-fold) of SH-PTP1 was achieved at 70 microM EPOR pY429, and the maximally activated enzyme approached the activity of SH-PTP1(delta SH2). Addition of EPOR pY429 peptide, which corresponds to the recently identified in vivo binding site for SH-PTP1, at 40 microM also completely restored the saturation kinetic behavior of SH-PTP1 (at pH 7.4) toward pNPP, with catalytic parameters (KM = 12.8 mM, kcat = 3.2 s-1) similar to those of SH-PTP1(delta SH2). These data suggest that the SH2 domains of SH-PTP1 serve to autoinhibit the phosphatase activity of the PTPase domain. A model is proposed in which the SH2 domains interact with the PTPase domain in a pY-independent fashion and drive the PTPase domain into an inactive conformation.

[Prenatal determination of lung maturity from amniotic fluid--indications and new methods]

Although fetal lung maturity determination is carried out more and more rarely in the German-speaking area, a reliable information about the degree of lung maturity is still very important in the care of high-risk pregnancies. The side effects and costs of a postpartal surfactant administration can be avoided if lung maturity is proved. Indications for determination of fetal lung maturity are the threatening preterm delivery and the premature rupture of membranes before the 34th week of gestation and uncertain gestational age. Furthermore, in preeclampsia resp. in diabetes mellitus, which is difficult to control, premature delivery may be necessary. To improve lung maturity testing we introduce a new "sequence scheme" containing three lung maturity tests which are easy to carry out (in the following sequence: Amniostat-FLM ultrasensitive, counting of the lamellar bodies in amniotic fluid, surfactant/albumin ratio with TDx-FLM). The principle of this scheme is, that if any of these three tests indicates lung maturity, the sequence is terminated and no further test is performed. Only if all three tests indicated immaturity, the child was at risk for RDS. In 87 amniotic fluid samples with 7 RDS-cases, we achieved high predictive values for lung maturity (specificity 90%, sensitivity 100%, predictive value of positive test 47%, predictive value of negative test 100%). In 62% only one test was needed for lung maturity determination. It is possible to use other combinations in such a scheme (e.g. the L/S ratio). This might lead to equal or perhaps better results. An advantage of this suggested "sequence scheme" is that it can be performed in any clinic.