Observation of in-medium modifications of the omega meson

The photoproduction of omega mesons on nuclei has been investigated using the Crystal Barrel/TAPS experiment at the ELSA tagged photon facility in Bonn. The aim is to study possible in-medium modifications of the omega meson via the reaction gamma + A --> omega + X --> pi(0)gamma + X('). Results obtained for Nb are compared to a reference measurement on a LH2 target. While for recoiling, long-lived mesons (pi(0), eta, and eta;(')), which decay outside of the nucleus, a difference in the line shape for the two data samples is not observed, we find a significant enhancement towards lower masses for omega mesons produced on the Nb target. For momenta less than 500 MeV/c an in-medium omega meson mass of M(medium) = [722(+4)(-4)(stat)+35-5(syst)] MeV/c(2) has been deduced at an estimated average nuclear density of 0.6rho(0).

Organic homojunction diodes with a high built-in potential: interpretation of the current-voltage characteristics by a generalized Einstein relation

We realize p- and n-type doping of the organic semiconductor zinc-phthalocyanine using a novel strong organic donor. This allows us to demonstrate the first stable and reproducible organic p-n homojunctions. The diodes show very high built-in potentials, attractive, e.g., for organic solar cells. However, the diode characteristics cannot be described by the standard Shockley theory of the p-n junction since the ideality factor strongly increases with decreasing temperature. We show that this behavior can be explained by deviations from the Einstein relation for disordered materials.

Atmosphere-ocean dynamics in the Western Indian Ocean recorded in corals

We present a set of Porites coral oxygen isotope records from the tropical and subtropical Western Indian Ocean covering the past 120-336 years. All records were thoroughly validated for proxy response to regional climate factors and their relation to large-scale climate modes. The records show markedly different imprints of regional climate factors. At the same time, all coral records show clear teleconnections between the Western Indian Ocean and the El Nino-Southern Oscillation (ENSO). The multi-proxy site analysis enables the detection of the covariance structure between individual records and climate modes such as ENSO. This method unravels shifts in ENSO teleconnectivity of the Western and Central Indian Ocean on multi-decadal time-scales (after 1976). The Seychelles record shows a stationary correlation with ENSO, Chagos corals show evidence for non-stationary delta18O/ENSO relationships and the Southwestern Indian Ocean corals show a strong relationship with ENSO when the forcing is strong (1880-1920, 1970 to present). Our results indicate that the coral delta18O, in combination with other proxies, can be used to monitor temporal and spatial variations in the sea-surface temperature and the fresh water balance within the Indian Ocean on interannual to interdecadal time-scales.

Photoproduction of eta-mesic 3He

The photoproduction of eta-mesic 3He has been investigated using the TAPS calorimeter at the Mainz Microtron accelerator facility MAMI. The total inclusive cross section for the reaction gamma3He-->etaX has been measured for photon energies from threshold to 820 MeV. The total and angular differential coherent eta cross sections have been extracted up to energies of 745 MeV. A resonancelike structure just above the eta production threshold with an isotropic angular distribution suggests the existence of a resonant quasibound state. This is supported by studies of a competing decay channel of such a quasibound eta-mesic nucleus into pi(0)pX. A binding energy of (-4.4+/-4.2) MeV and a width of (25.6+/-6.1) MeV is deduced for the quasibound eta-mesic state in 3He.

[Surgical treatment of osteoid osteoma of the extremities]

AIM

It was the aim of this retrospective study to evaluate the frequency of recurrences and complications in patients treated by conventional surgical methods at our institution between 1980 and 1996 and to compare them to those observed in patients treated by minimal invasive methods reported in the literature.

METHOD

70 patients with osteoid osteomas located at the extremities were treated by conventional surgical treatment. 51 patients underwent curettage and 19 patients had en bloc resection. After curettage an additional stabilising plate was implanted in 12% of the cases, after en bloc resection in 68%.

RESULTS

There are 66% event-free patients after curettage versus 47% after en bloc resection. Local recurrence rate after curettage was 7%, after en bloc resection no patient developed a recurrence. In both groups a postoperative fracture was observed. Persistent pain due to the implant was reported by 7% after curettage and by 24% after en bloc resection.

CONCLUSION

The rate of complications rises with increasing invasiveness and it is necessary to balance the security concerning a local recurrence and the danger of persistent postoperative pain. Curettage is the surgical method of choice in the therapy of the osteoid osteoma, en bloc resection is justified only for recurrent lesions. Curettage is an alternative to minimal invasive methods in cases of superficially located osteoid osteomas or in cases of unfavourable locations of the nidus (near joint or growth plate, inaccessibility).

The reaction gammap-->pi0gamma'p and the magnetic dipole moment of the Delta+ 1232 resonance

The reaction gammap-->pi(0)gamma'p has been measured with the TAPS calorimeter at the Mainz Microtron accelerator facility MAMI for energies between sqrt[s]=1221-1331 MeV. The cross section's differential in angle and energy have been determined for the photon gamma' in three bins of the excitation energy. This reaction channel provides access to the magnetic dipole moment of the Delta(+)(1232) resonance and, for the first time, a value of mu(Delta(+))=[2.7(+1.0)(-1.3)(stat)+/-1.5(syst)+/-3(theor)]mu(N) has been extracted.

In-medium modifications of the pipi interaction in photon-induced reactions

Differential cross sections of the reactions (gamma,pi(0)pi(0)) and (gamma,pi(0)pi(+/-)) have been measured for several nuclei (1H,12C, and (nat)Pb) at an incident-photon energy of E(gamma)=400-460 MeV at the tagged-photon facility at MAMI-B using the TAPS spectrometer. A significant nuclear-mass dependence of the pipi invariant-mass distribution is found in the pi(0)pi(0) channel. This dependence is not observed in the pi(0)pi(+/-) channel and is consistent with an in-medium modification of the pipi interaction in the I=J=0 channel. The data are compared to pi-induced measurements and to calculations within a chiral-unitary approach.

[Osteosarcoma and Ewing's sarcoma--The most frequent malignant bone tumors in children--therapy and outcome]

BACKGROUND

Osteosarcoma and Ewing's sarcoma are the most frequent malignant bone tumors in children and young adults with relatively poor overall survival rates.

METHODS

Between January 1980 and December 1994, 175 children with osteosarcoma and 64 children with Ewing's sarcoma were treated at the author's institution. 22 children had synchronous metastases, 19 patients had a pathologic fracture. Both groups were treated systemically with chemotherapy regimens (COSS and CESS). Local therapy was amputation or tumor resection and endoprosthetic replacement or biological reconstruction with wide or radical resection margins. In case of Ewing's sarcoma in 35 patients postoperative radiation therapy was done.

RESULTS

Five-year overall survival rate for osteosarcoma and Ewing's sarcoma patients is about 63 %, ten-year survival rate for osteosarcoma patients is 60.2 %, for Ewing's sarcoma patients 54.5 %. Prognostic factors significantly influencing overall survival rates are tumor response to chemotherapy (p values = 0.0056 and 0.013, respectively), surgical treatment with adequate resection margins (p value = 0.0001 for osteosarcoma patients) and development of postoperative metastases (p value = 0.0001 for both groups).

CONCLUSION

For both groups of malignant bone tumors systemic chemotherapy as well as adequate surgical therapy are necessary to reduce the rates of local recurrences and to achieve better survival rates.

Peripheral osteoid osteoma. Is there still a place for traditional surgery?

We treated 106 patients with a peripheral osteoid osteoma by conventional surgical methods; 81 had curettage and 25 en-bloc resection. The rate of local recurrence after curettage was 12% and after en-bloc resection 4.5%. Postoperative fractures were observed in 3% after curettage and in 4.5% after en-bloc resection. We compared our findings with those reported in the literature after minimally invasive treatment and concluded that curettage can be regarded as the treatment of choice in patients in whom minimally invasive methods do not offer any advantage, for example, for subperiosteal tumours which are readily accessible, or when the diagnosis is unclear and further histological analysis is required.

Peripheral osteoid osteoma

We treated 106 patients with a peripheral osteoid osteoma by conventional surgical methods; 81 had curettage and 25 en-bloc resection.

The rate of local recurrence after curettage was 12% and after en-bloc resection 4.5%. Postoperative fractures were observed in 3% after curettage and in 4.5% after en-bloc resection.

We compared our findings with those reported in the literature after minimally invasive treatment and concluded that curettage can be regarded as the treatment of choice in patients in whom minimally invasive methods do not offer any advantage, for example, for subperiosteal tumours which are readily accessible, or when the diagnosis is unclear and further histological analysis is required.

Clinical scale isolation of T cell-depleted CD56+ donor lymphocytes in children

We present a clinical scale method for immunomagnetic separation of CD56+ donor natural killer cells for adoptive immunotherapy of pediatric leukemias after allogeneic transplantation. This time-saving and partially automated procedure employed CD56+ selection followed by CD3+ depletion, resulting in a median purity of 98.6% NK cells and a four-log depletion of T cells. The enriched NK cells demonstrated high cytotoxic activity against K562 target cells and fresh leukemic blasts with low HLA class I expression, which could be further enhanced by IL-2 stimulation. Lysis of NK-insensitive leukemic cells with high HLA class I expression could also be demonstrated via ADCC. Due to the high degree of T cell depletion, alloreactive proliferation in mixed lymphocyte cultures and response to T cell-specific mitogen stimulation was profoundly decreased. Our results suggest that, even in the case of mismatched donors, infusions of donor NK cells with extremely low T cell content may be a promising treatment option for leukemic minimal residual disease after allogeneic transplantation without risk of inducing severe GVHD.

[Spiroergometry in patients with severe chronic obstructive pulmonary disease confined to bed]

BACKGROUND

Exercise training is recommended for patients with severe chronic obstructive pulmonary disease (COPD) to improve the endurance capacity. While many patients confined to bed are not able to run exercise training, we investigated the influence of a bedside passive-ergometry on ventilation in patients with severe COPD.

METHODS

In nine patients with severe COPD confined to bed (FEV1.0 0,94 +/- 0,18 l, IVC 2,3 +/- 0,8 l, Raw 0,91 +/- 0,13 kPa/l/s) we measured oxygen uptake O2, breathing frequency BF and minute ventilation E during rest, passive movement (30 revolutions per minute), additional active movement and maximal exercise. As a control group six healthy men were investigated during rest and passive movement.

RESULTS

During maximal exercise in COPD patients O2 peak reached 618 +/- 177 ml/min, BF 26 +/- 7,2/min and E max 24,1 +/- 5 l/min. In rest O2 was 311 +/- 56 ml/min (53 % O2 peak), BF 17,6 +/- 3,1/min and E 13,3 +/- 2,7 ml/min (55 % E max), while during passive movement O2 was increased to 369 +/- 88 (62 % O2 peak), BF to 19 +/- 5,3 and E to 16,4 +/- 4,1 (68 % E max). In contrast O2 in control subjects dropped from 377,5 +/- 38 in rest to 336 +/- 27 ml/min during passive action, BF from 14 +/- 2,1 to 12 +/- 2,4/min and E from 11,1 +/- 1,3 to 9,1 +/- 1 ml/min.

CONCLUSIONS

In patients with severe COPD oxygen uptake, breathing frequency and minute ventilation increased not only during active, but even during passive movement of a bedside ergometer. With this method an exercise training is possible even in COPD patients confined to bed.

Systemic and local antibiotic prophylaxis in the prevention of prosthetic vascular graft infection: an experimental study

AIM

to determine if local, in addition to systemic antibiotic prophylaxis (compared to that provided by systemic prophylaxis alone) provides additional benefit in terms of reducing graft infection.

METHODS

gelatin-sealed Dacron grafts were interposed in the infrarenal aorta of 36 mongrels and inoculated with 1 ml of a S. aureus suspension. Group 1 (control group) received no prophylaxis and were inoculated with 1 ml containing 10(9)cfu/ml. Group 2 (n=6) received systemic prophylaxis (1 g cephamandole) and were inoculated with 10(5) cfu/ml (n=3) or 10(7) cfu/ml (n=3). Group 3 received systemic prophylaxis (1 g cephamandole) and were inoculated with 109 cfu/ml. Group 4 received systemic prophylaxis (2 g cephamandole) and were inoculated with 10(9)cfu/ml. In group 5 and 6 grafts were soaked in a rifampicin solution before use and inoculated with 10(9) cfu/ml. Group 5 received no systemic prophylaxis and group 6 received systemic prophylaxis (1 g cephamandole). Grafts were harvested at 2 weeks, and peritonitis, perigraft abscess, anastomotic disruption and graft occlusion recorded. Swabs were taken of the graft, the perigraft tissues and the peritoneal fluid. Graft segments were incubated in broth medium.

RESULTS

inoculation with 10(9) cfu/ml ensured graft infection. Systemic or local prophylaxis alone failed to prevent graft infection. Only systemic and local antibiotic prophylaxis provided significant better results than no prophylaxis at all (p<0.01) and local prophylaxis alone (p<0.05). However, total "graft sterility" was not achieved as bacteriologic analysis of the graft segments showed low bacterial counts (<10 bacteria/graft) in 5 of 6 grafts.

CONCLUSION

local and systemic prophylaxis provided more protection as demonstrated by the significant decrease in the incidence of "overt" graft infection. Total "graft sterility" cannot be expected in the case of an overwhelming bacterial challenge.

A new semirigid implant for instrumentation of scoliosis: preliminary report

A new set of pedicle screws, lamina and pedicle hooks, longitudinal rods and a titanium cable was developed to overcome the increasingly obvious hazards of overly rigid spinal instrumentation. Results of the first 12 consecutive scoliosis patients with this new system are reported, with an average follow-up time of 18 months. No major complications occurred. The average correction of the deformity was well within the range of more rigid systems. The new Dorsal Dynamic Spondylodesis (DDS) system proved to be easy to use, fast, powerful, safe, versatile, and biomechanically sound. Reduction of stress-shielding effects and protection of adjacent segments can be expected, and the system warrants future application in selected prospective cases with long-term follow-up.

C-terminal Splice Variants of the Mouse µ-Opioid Receptor Differ in Morphine-induced Internalization and Receptor Resensitization

The main analgesic effects of the opioid alkaloid morphine are mediated by the mu-opioid receptor. In contrast to endogenous opioid peptides, morphine activates the mu-opioid receptor without causing its rapid endocytosis. Recently, three novel C-terminal splice variants (MOR1C, MOR1D, and MOR1E) of the mouse mu-opioid receptor (MOR1) have been identified. In the present study, we show that these receptors differ substantially in their agonist-selective membrane trafficking. MOR1 and MOR1C stably expressed in human embryonic kidney 293 cells exhibited phosphorylation, internalization, and down-regulation in the presence of the opioid peptide [d-Ala(2),Me-Phe(4),Gly(5)-ol]enkephalin (DAMGO) but not in response to morphine. In contrast, MOR1D and MOR1E exhibited robust phosphorylation, internalization, and down-regulation in response to both DAMGO and morphine. DAMGO elicited a similar desensitization (during an 8-h exposure) and resensitization (during a 50-min drug-free interval) of all four mu-receptor splice variants. After morphine treatment, however, MOR1 and MOR1C showed a faster desensitization and no resensitization as compared with MOR1D and MOR1E. These results strongly reinforce the hypothesis that receptor phosphorylation and internalization are required for opioid receptor reactivation thus counteracting agonist-induced desensitization. Our findings also suggest a mechanism by which cell- and tissue-specific C-terminal splicing of the mu-opioid receptor may significantly modulate the development of tolerance to the various effects of morphine.

Direct observation of different surface structures on high-resolution images of native halorhodopsin

Halorhodopsin (HR) was investigated with atomic force microscopic techniques (AFM) in aqueous solution. Two-dimensional (2D) crystals of HR were obtained by purifying an HR membrane fraction with the same buoyant density as the purple membrane (HR-PM) from the overexpressing strain Halobacterium salinarum D2. The membrane patches of HR were immobilized on mica. Images with a resolution up to 14 A were recorded. Crystals showed an orthogonal structure and the orientation of the molecules showed p42(1)2 symmetry; thus, alternate tetramers are inverted in the membrane. The crystal surface was found to display different structures depending on the imaging force used, indicating that some parts of the HR molecule are more rigid but others more compressible. From samples with single tetramers missing in the crystalline patches dimensions of the unit cell could be determined. Helix-connecting loops in single molecules of halorhodopsin were assigned. The images indicate that the large extracellular BC loop covers the whole molecule and is very flexible.