Gentoo penguins (Pygoscelis papua) react to underwater sounds.

Marine mammals and diving birds face several physiological challenges under water, affecting their thermoregulation and locomotion as well as their sensory systems. Therefore, marine mammals have modified ears for improved underwater hearing. Underwater hearing in birds has been studied in a few species, but for the record-holding divers, such as penguins, there are no detailed data. We played underwater noise bursts to gentoo penguins (Pygoscelis papua) in a large tank at received sound pressure levels between 100 and 120 dB re 1 µPa RMS. The penguins showed a graded reaction to the noise bursts, ranging from no reactions at 100 dB to strong reactions in more than 60% of the playbacks at 120 dB re 1 µPa. The responses were always directed away from the sound source. The fact that penguins can detect and react to underwater stimuli may indicate that they make use of sound stimuli for orientation and prey detection during dives. Further, it suggests that penguins may be sensitive to anthropogenic noise, like many species of marine mammals.

Marine debris in harbour porpoises and seals from German waters.

Records of marine debris in and attached to stranded harbour porpoises (Phocoena phocoena), harbour seals (Phoca vitulina) and grey seals (Halichoerus grypus) were studied comprising information on 6587 carcasses collected along the German coast between 1990 and 2014, the decomposition state allowed for necropsy in 1622 cases. Marine debris items were recorded in 31 carcasses including 14 entanglements (5 harbour porpoises, 6 harbour seals, 3 grey seals) and 17 cases of ingestion (4 harbour porpoises, 10 harbour seals, 3 grey seals). Objects comprised general debris (35.1%) and fishing related debris (64.9%). Injuries associated with marine debris included lesions, suppurative ulcerative dermatitis, perforation of the digestive tract, abscessation, suppurative peritonitis and septicaemia. This study is the first investigation of marine debris findings in all three marine mammal species from German waters. It demonstrates the health impacts marine debris can have, including severe suffering and death. The results provide needed information on debris burdens in the North and Baltic Seas for implementing management directives, such as the Marine Strategy Framework Directive (MSFD).

Self-organized formation of GaSb/GaAs quantum rings.

Ring-shaped GaSb/GaAs quantum dots, grown by molecular beam epitaxy, were studied using cross-sectional scanning tunneling microscopy. These quantum rings have an outer shape of a truncated pyramid with baselengths around 15 nm and heights of about 2 nm but are characterized by a clear central opening extending over about 40% of the outer baselength. They form spontaneously during the growth and subsequent continuous capping of GaSb/GaAs quantum dots due to the large strain and substantial As-for-Sb exchange reactions leading to strong Sb segregation.

Submonolayer quantum dots for high speed surface emitting lasers.

We report on progress in growth and applications of submonolayer (SML) quantum dots (QDs) in high-speed vertical-cavity surface-emitting lasers (VCSELs). SML deposition enables controlled formation of high density QD arrays with good size and shape uniformity. Further increase in excitonic absorption and gain is possible with vertical stacking of SML QDs using ultrathin spacer layers. Vertically correlated, tilted or anticorrelated arrangements of the SML islands are realized and allow QD strain and wavefunction engineering. Respectively, both TE and TM polarizations of the luminescence can be achieved in the edge-emission using the same constituting materials. SML QDs provide ultrahigh modal gain, reduced temperature depletion and gain saturation effects when used in active media in laser diodes. Temperature robustness up to 100 °C for 0.98 µm range vertical-cavity surface-emitting lasers (VCSELs) is realized in the continuous wave regime. An open eye 20 Gb/s operation with bit error rates better than 10-12has been achieved in a temperature range 25-85 °Cwithout current adjustment. Relaxation oscillations up to ∼30 GHz have been realized indicating feasibility of 40 Gb/s signal transmission.

[Computer assisted pelvic and acetabular surgery. Clinical experiences and indications]. / Navigationsverfahren in der Becken- und Azetabulumchirurgie Klinische Erfahrungen, Indikationen und Grenzen.

CT based navigation has been used in spine surgery since 1994. Several clinical studies could show an increase in precision compared to the conventional technique and thus nowadays the navigated pedicle screw placement is a routine procedure in many hospitals. Based upon the experience in spine surgery the CT based navigation module was used for percutaneous screw fixations in minimally displaced pelvic ring and acetabular fractures. After preclinical experimental trials the C-arm navigation was used for 19 screw fixations. The postoperative control of the screw position was performed with postop. X-ray and CT. Overall 23 of the 24 screws were placed correctly. In one SI screw the postoperative CT could reveal a ventral cortex perforation of the sacrum without any clinical symptoms. Based upon this limited clinical experience we see the indication for CT based navigation in minimally displaced acetabular fractures or in SI screw fixations in case of sacral dysplasia. The C-arm based navigation with adequate image quality is our method of choice for SI screw fixation in traumatic or degenerative instabilities, especially if reduction maneuvers are necessary.

The effect of growth hormone on insulin-like growth factor I and bone metabolism in distraction osteogenesis.

Limb lengthening in the left tibia of 30 mature female Yucatan micropigs was performed using distraction osteogenesis. A treatment group of 15 animals received recombinant porcine growth hormone (r-pGH) (100 microg/kg/day) while the others served as controls. Serial serum measurements of total insulin-like growth factor I (IGF-I), free IGF-I, IGF binding proteins -1, -2, -3 and -4 (IGFBP-1 to -4) were performed. Bone-specific alkaline phosphatase (bone-ALP) and the serum carboxyl-terminal telopeptide of type I collagen (ICTP) were measured as bone turnover markers. The GH-treated animals showed a significant increase in total IGF-I, free IGF-I and IGFBP-3 after surgery (P<0.001). Similarly, the treated animals showed a significantly higher level of bone-ALP (P<0.001) throughout the experiment compared to the controls. There was a significant correlation between bone-ALP and total IGF-I (r=0.76) in the GH-treated group and an even higher correlation for free IGF-I (r=0.90). There was no difference in the ICTP serum levels between the two groups. These data indicate that the application of species-specific growth hormone results in a stimulation of bone formation in distraction osteogenesis which may be mediated by IGF-I. The stronger correlation between free IGF-I and bone-ALP indicates that the anabolic effect of IGF-I may be regulated through the IGFBPs by binding and inactivating IGF-I.

Homologous growth hormone accelerates healing of segmental bone defects.

The effect of homologous recombinant porcine growth hormone (r-pGH) on secondary fracture healing was investigated in a diaphyseal defect of the tibia in Yucatan micropigs. A 1 cm defect of the tibia was created surgically and stabilized with an AO 3.5 mm DCP plate. The treatment group (12 animals) received 100 microg of r-pGH per kilogram of body weight subcutaneously once per day, whereas the control pigs (12 animals) received 1 mL of sodium chloride as placebo. For evaluation of the GH-axis, serum levels of insulin-like growth factor-I (IGF-I) were sampled every fourth day. The animals were killed 6 weeks after surgery. Quantitative computed tomography (qCT) was performed to determine bone mineral density (BMD) and bone mineral content (BMC) of the defect zone. The torsional stiffness and the torsional failure load were measured by destructive torsional testing of the defect and contralateral tibiae. qCT measurements revealed a significant increase in the BMC of the defect zone in the treatment group compared with controls (GH BMC = 2833 +/- 679 mg, placebo BMC = 2215 +/- 636 mg; p < 0.05), whereas the BMD values were similar in both groups (GH BMD = 668 +/- 60 mg/mm(2), placebo BMD = 629 +/- 52 mg/mm(2), p = 0.12). Torsional failure load was 70% higher and torsional stiffness 83% higher in the treatment group than in the control group (p < 0.05). The mean serum level of IGF-I in the treatment group increased to 382% of the preoperative basal level and decreased to 69% in the control group, and this difference was highly significant (p < 0.001). Our data indicate that daily administration of recombinant GH leads to an increase of serum IGF-I levels and stimulates secondary fracture healing, resulting in increased mechanical strength and stiffness of the callus.

[Recombinant growth hormone accelerates regenerate consolidation in distraction osteosynthesis]. / Rekombinantes Wachstumshormon beschleunigt die Regeneratkonsolidierung bei der Distraktionsosteogenese.

Distraction osteogenesis is a good model for evaluation of fracture healing with intramembranous bone formation. The purpose of the present study was to investigate whether homologous GH has a stimulating effect on bone healing in distraction osteogenesis. The left tibiae of 30 micropigs were osteomized and distracted with an external fixator 2 mm daily over a period of 10 days. Animals were killed after an additional healing time of 10 days. The treatment group received 100 micrograms r-pGH per kg bodyweight per day. A newly developed device allowed non-destructive torsional biomechanical evaluation of the regenerate strength as in vivo measurements. After killing, destructive torsional strength testing of the sites of distraction was performed. To determine the endocrine response to the administration of r-pGH, serum levels of IGF-I were determined. The non-destructive in vivo testing showed that torsional stiffness of the regenerate was significantly higher in the treatment group than in the control group. Final regenerate torsional failure load was 131% higher and ultimate torsional stiffness was 231% higher in the treatment group than in the control group. The mean serum level of IGF-I increased to 440% of the preoperative base level in the treatment group and remained unchanged in the control group. Our data indicate that systemic administration of recombinant homologous growth hormone significantly accelerates ossification of bone regenerate in distraction osteogenesis.