Publications by authors named "Harald Beck"

10 Publications

  • Page 1 of 1

Changes in tree community structure in defaunated forests are not driven only by dispersal limitation.

Ecol Evol 2020 Apr 9;10(7):3392-3401. Epub 2020 Mar 9.

Department of Biology and Florida Museum of Natural History University of Florida Gainesville FL USA.

Bushmeat hunting has reduced population sizes of large frugivorous vertebrates throughout the tropics, thereby reducing the dispersal of seeds. This is believed to affect tree population dynamics, and therefore community composition, because the seed dispersal of large-seeded trees depends upon large-bodied vertebrates.We report on a long-running study of the effect of defaunation on a tropical tree community. In three censuses over 11 years, we compared sapling recruitment between a hunted and a nonhunted site, which are nearby and comparable to one another, to determine the extent to which species composition has changed through time following defaunation. We expected to find a reduced abundance of tree species that rely on large frugivores for dispersal at the hunted site and altered community structure as a consequence.Although community composition at the hunted site diverged from that at the nonhunted site, the changes were independent of dispersal syndrome, with no trend toward a decline in species that are dispersed by large, hunted vertebrates. Moreover, the loss of large-bodied dispersers did not generate the changes in tree community composition that we hypothesized. Some species presumed to rely on large-bodied frugivores for dispersal are effectively recruiting despite the absence of their dispersers.Synthesis: The presumption that forests depleted of large-bodied dispersers will experience rapid, directional compositional change is not fully supported by our results. Altered species composition in the sapling layer at the hunted site, however, indicates that defaunation may be connected with changes to the tree community, but that the nature of these changes is not unidirectional as previously assumed. It remains difficult to predict how defaunation will affect tree community composition without a deeper understanding of the driving mechanisms at play.
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http://dx.doi.org/10.1002/ece3.6133DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7140993PMC
April 2020

Gaps present a trade-off between dispersal and establishment that nourishes species diversity.

Ecology 2020 05 9;101(5):e02996. Epub 2020 Mar 9.

Department of Biological Sciences, Towson University, 8000 York Road, Towson, Maryland, 21252, USA.

We took advantage of two natural experiments to investigate processes that regulate tree recruitment in gaps. In the first, we examined the recruitment of small and large saplings and trees into 31 gaps resulting from treefalls occurring between 1984 and 2015 in the 2.25-ha core area of a 4-ha tree plot at Cocha Cashu in Perú. In the second, we identified the tallest saplings recruiting into 69 gaps created during a violent wind storm in February 2000. In the established tree plot, we were able to compare the composition of saplings in the disturbance zones of gaps prior to, during, and subsequent to the period of gap formation. Recruitment in gaps was compared with that in "nofall" zones, areas within the plot that had not experienced a treefall at least since the early 1980s. Our results confirmed earlier findings that a consistently high proportion (~60%) of established saplings survived gap formation. Light demanding species, as proxied by mortality rates, recruited under all conditions, but preferentially during periods of gap formation, a pattern that was especially strong among gap pioneers. Similar results were noted, separately, for small and large saplings and trees recruiting at ≥10 cm dbh. One hundred percent of previously untagged trees recruiting into gaps in the first post-disturbance census were gap pioneers, suggesting rapid development. This conclusion was strongly supported in a follow-up survey taken of 69 gaps 19 months after they had been synchronously created in a wind storm. Ten species of gap pioneers, eight of which are not normally present in the advance regeneration, had attained heights of 6-10 m in 19 months. The 10 gap pioneers were dispersed, variously, by primates, bats, birds, and wind and reached maximum frequency in different-sized gaps (range <100 m to >1,000 m ). Both gap size and limited dispersal of zoochorous species into gaps serve as filters for establishment, creating a complex mosaic of conditions that enhances species diversity.
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http://dx.doi.org/10.1002/ecy.2996DOI Listing
May 2020

How mammalian predation contributes to tropical tree community structure.

Ecology 2016 Dec;97(12):3326-3336

Duke University Center for Tropical Conservation, Nicholas School of the Environment and Earth Sciences, PO Box 90318, Durham, North Carolina, 27708, USA.

The recruitment of seedlings from seeds is the key demographic transition for rain forest trees. Though tropical forest mammals are known to consume many seeds, their effects on tree community structure remain little known. To evaluate their effects, we monitored 8,000 seeds of 24 tree species using exclosure cages that were selectively permeable to three size classes of mammals for up to 4.4 years. Small and medium-bodied mammals removed many more seeds than did large mammals, and they alone generated beta diversity and negative density dependence, whereas all mammals reduced diversity and shaped local species composition. Thus, small and medium-bodied mammals more strongly contributed to community structure and promoted species coexistence than did large mammals. Given that seedling recruitment is seed limited for most species, alterations to the composition of the community of mammalian seed predators is expected to have long-term consequences for tree community structure in tropical forests.
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http://dx.doi.org/10.1002/ecy.1586DOI Listing
December 2016

Human but not mouse adipogenesis is critically dependent on LMO3.

Cell Metab 2013 Jul;18(1):62-74

Department of Laboratory Medicine, Medical University of Vienna, 1090 Vienna, Austria.

Increased visceral fat is associated with a high risk of diabetes and metabolic syndrome and is in part caused by excessive glucocorticoids (GCs). However, the molecular mechanisms remain undefined. We now identify the GC-dependent gene LIM domain only 3 (LMO3) as being selectively upregulated in a depot-specific manner in human obese visceral adipose tissue, localizing primarily in the adipocyte fraction. Visceral LMO3 levels were tightly correlated with expression of 11β-hydroxysteroid dehydrogenase type-1 (HSD11B1), the enzyme responsible for local activation of GCs. In early human adipose stromal cell differentiation, GCs induced LMO3 via the GC receptor and a positive feedback mechanism involving 11βHSD1. No such induction was observed in murine adipogenesis. LMO3 overexpression promoted, while silencing of LMO3 suppressed, adipogenesis via regulation of the proadipogenic PPARγ axis. These results establish LMO3 as a regulator of human adipogenesis and could contribute a mechanism resulting in visceral-fat accumulation in obesity due to excess glucocorticoids.
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http://dx.doi.org/10.1016/j.cmet.2013.05.020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3701325PMC
July 2013

Influence of brachial plexus blockade on oxygen balance during surgery.

Anesth Analg 2011 Jul 27;113(1):199-201. Epub 2011 Apr 27.

Department of Surgery, Division of Plastic and Reconstructive Surgery, Vienna General Hospital, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria.

The combined effects of anesthesia, motor blockade, and chemically induced sympathectomy after brachial plexus blockade can have a beneficial impact, when applied in selected, isolated diseased states of the upper limb. With the aim of using the prolonged effects of brachial plexus blockade for a future therapeutic application, we demonstrated a dependable methodology of venous blood gas monitoring and confirmed an improved oxygen balance of the blocked versus nonblocked upper extremity in a controlled, prospective study in healthy patients undergoing elective hand surgery.
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http://dx.doi.org/10.1213/ANE.0b013e31821893f4DOI Listing
July 2011

Electrical injury: a long-term analysis with review of regional differences.

Ann Plast Surg 2011 Jan;66(1):43-6

Division of Plastic and Reconstructive Surgery, Department of Surgery, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria.

Due to its relatively small share among burn injuries, published data on electrical injuries remain scarce, and differ in patient collectives due to infrastructural differences. We have retrospectively analyzed records of 56 patients who were admitted because of electrical injury to our burn center from 1994 to 2008, compared results with the current literature, and focused our review on regional differences. Patients in our collective were predominantly young men (71%, n = 40/56) and those who resulted from work-related accidents (59%, n = 33/56). The mean total burn surface area was 26%. In all, 93% of patients needed at least 1 operation, with 43% of patients requiring at least 1 surgical intervention during a follow-up hospital stay. The mean length-of-stay was 44 days. Two patients died, accounting for a mortality rate of 3.6%. When comparing high to low-voltage injuries, patients in the former group were significantly younger, had more operations, and required a longer length-of-stay. With respect to work-related high-voltage injuries, job-specific male-predominance explains for the demographic distribution of admissions. Low-voltage injuries continue to have low mortality rates in this part of Europe, most likely as a result of established high security standards as well as access to emergency treatment with subsequent intensive and specialist surgical care.
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http://dx.doi.org/10.1097/SAP.0b013e3181f3e60fDOI Listing
January 2011

Long-term outcomes of web creep, scar quality, and function after simple syndactyly surgical treatment.

J Hand Surg Am 2010 Aug 16;35(8):1323-9. Epub 2010 Jul 16.

Division of Plastic and Reconstructive Surgery, Department of Surgery, Vienna General Hospital, Medical University of Vienna, Vienna, Austria.

Purpose: Syndactyly is the second most common congenital malformation of the hand, and reports of the incidence of web creep after surgery vary. To evaluate our outcomes of simple syndactyly surgical release, we conducted a retrospective analysis of patients treated between January 1965 and December 2007.

Methods: After matching for inclusion criteria, we recruited 19 patients with 26 affected web spaces for clinical examination. Outcomes evaluation included grading of web creep, Vancouver Scar Scale, assessment of complications and subjective patient analysis, range of motion, degree of finger abduction, power, and 2-point discrimination. Mean age at follow-up was 18 years (range, 6-50 y), with a mean age of 4.4 years (range, 7 mo to 15 y) at surgery and mean follow-up of 11.5 years (range, 5-35 y). Surgical management consisted of palmar and dorsal triangular skin flaps for creation of the new commissure, and multiple zigzag incisions for separation of digits. For tension-free closure, full-thickness skin grafts were harvested as needed.

Results: We observed web creep up to the proximal third of the distance between palmar metacarpophalangeal and proximal interphalangeal joint crease in 2 web spaces. All other web spaces had either a soft web equivalent to the contralateral (unaffected) side (n = 13) or no web advancement with thickening of the interdigital space (n = 11). The scar quality as assessed with the Vancouver Scar Scale revealed a height below 2 mm in 24 of 26 web spaces, with close to normal to supple pliability in 20 of 26 web spaces. There were no considerable differences for range of motion, degree of finger abduction, power, or 2-point discrimination between the affected and unaffected sides. In 17 of 24 cases in which full-thickness skin grafts from the groin region were used, patients reported commissural hair growth in the grafted region.

Conclusions: Evaluation of the long-term outcomes of surgical treatment for simple syndactyly at our institution demonstrated a low incidence of web creep. When choosing the groin as a donor area for full thickness skin grafts, we recommend harvesting from the lateral third of the inguinal crease, to avoid esthetic compromise associated with the beginning of hair growth in puberty.

Type Of Study/level Of Evidence: Therapeutic IV.
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http://dx.doi.org/10.1016/j.jhsa.2010.04.033DOI Listing
August 2010

The anatomic basis of the internal mammary artery perforator flap: a cadaver study.

J Plast Reconstr Aesthet Surg 2010 Feb 3;63(2):191-6. Epub 2009 Jan 3.

Division of Plastic and Reconstructive Surgery, Department of Surgery, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria.

Introduction: The perforating branches of the internal mammary artery have recently been described as recipient vessel for free-tissue transfer breast reconstruction. However, reports on perforator flaps based on these vessels are rare. The aim of this study was to investigate the vascular basis of the internal mammary artery perforator (IMAP) flap and to describe the location and size of the individual flaps.

Material And Methods: The IMAPs of 10 fresh female cadavers were injected with methylene blue solution. The location and size of the labelled skin area were observed. Finally, the arterial perforators were dissected, and the length, diameter and the distance of the lateral sternal border to the perforation point were recorded.

Results: The IMAPs supplied the skin of the ventromedial thorax and breast from the clavicle to the skin of the cranial abdominal wall in a sequential order. The mean size of all injected skin areas was 84+/-54 cm(2) (13 x 7 cm). The biggest detected skin dimensions were 16 x 9 cm on average for IMAP 2 (area 138+/-41 cm(2)). The mean external diameter of the IMAP was 1.3+/-0.5 mm (range: 0.4-2.9 mm). The mean dissectible length was 8.3+/-3.6 cm (range: 3-17 cm). The largest diameter was found for IMAP 2 with a mean of 1.6+/-0.5 mm (range: 0.9-2.3 mm).

Conclusions: In the present study, a reliable anatomy of the IMAP flap could be demonstrated. Based on these results, different clinical applications exist for the individual IMAP flaps. The flaps based on IMAP 1 or 2 may be rotated cranially for tracheostoma or anterior neck reconstruction. The flaps based on IMAP 4 supplying the skin of the inframammary fold could be used for reconstruction of the contralateral thoracic wall or breast. The harvest site of IMAP 1 and 2 can be closed directly if the width of the flap is less than 6 cm. The IMAP 4 harvest site could be closed via a reduction mammaplasty technique, thus minimising donor-site morbidity.
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http://dx.doi.org/10.1016/j.bjps.2008.09.019DOI Listing
February 2010

Seed predation by Neotropical rain forest mammals increases diversity in seedling recruitment.

Ecology 2007 Dec;88(12):3076-87

Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, USA.

Seed dispersal and seedling recruitment (the transition of seeds to seedlings) set the spatiotemporal distribution of new individuals in plant communities. Many terrestrial rain forest mammals consume post-dispersal seeds and seedlings, often inflicting density-dependent mortality. In part because of density-dependent mortality, diversity often increases during seedling recruitment, making it a critical stage for species coexistence. We determined how mammalian predators, adult tree abundance, and seed mass interact to affect seedling recruitment in a western Amazonian rain forest. We used exclosures that were selectively permeable to three size classes of mammals: mice and spiny rats (weighing <1 kg), medium-sized rodents (1-12 kg), and large mammals (20-200 kg). Into each exclosure, we placed seeds of 13 tree species and one canopy liana, which varied by an order of magnitude in adult abundance and seed mass. We followed the fates of the seeds and resulting seedlings for at least 17 months. We assessed the effect of each mammalian size class on seed survival, seedling survival and growth, and the density and diversity of the seedlings that survived to the end of the experiment. Surprisingly, large mammals had no detectable effect at any stage of seedling recruitment. In contrast, small- and medium-sized mammals significantly reduced seed survival, seedling survival, and seedling density. Furthermore, predation by small mammals increased species richness on a per-stem basis. This increase in diversity resulted from their disproportionately intense predation on common species and large-seeded species. Small mammals thereby generated a rare-species advantage in seedling recruitment, the critical ingredient for frequency dependence. Predation by small (and to a lesser extent, medium-sized) mammals on seeds and seedlings significantly increases tree species diversity in tropical forests. This is the first long-term study to dissect the effects of various mammalian predators on the recruitment of a diverse set of tree species.
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http://dx.doi.org/10.1890/06-1835.1DOI Listing
December 2007

Ultrasound-guided lumbar facet nerve block: a sonoanatomic study of a new methodologic approach.

Anesthesiology 2004 May;100(5):1242-8

Department of Anesthesiology and General Intensive Care (B), Medical University of Vienna, Währinger-Gürtel 18-20, A-1090 Vienna, Austria.

Background: Lumbar facet nerve (medial branch) block for pain relief in facet syndrome is currently performed under fluoroscopic or computed tomography scan guidance. In this three-part study, the authors developed a new ultrasound-guided methodology, described the necessary landmarks and views, assessed ultrasound-derived distances, and tested the clinical feasibility.

Methods: (1) A paravertebral cross-axis view and long-axis view were defined under high-resolution ultrasound (15 MHz). Three needles were guided to the target point at L3-L5 in a fresh, nonembalmed cadaver under ultrasound (2-6 MHz) and were subsequently traced by means of dissection. (2) The lumbar regions of 20 volunteers (9 women, 11 men; median age, 36 yr [23-67 yr]; median body mass index, 23 kg/m2 [19-36 kg/m2]) were studied with ultrasound (3.5 MHz) to assess visibility of landmarks and relevant distances at L3-L5 in a total of 240 views. (3) Twenty-eight ultrasound-guided blocks were performed in five patients (two women, three men; median age, 51 yr [31-68 yr]) and controlled under fluoroscopy.

Results: In the cadaver, needle positions were correct as revealed by dissection at all three levels. In the volunteers, ultrasound landmarks were delineated as good in 19 and of sufficient quality in one (body mass index, 36 kg/m2). Skin-target distances increased from L3 to L5, reaching statistical significance (*, **P < 0.05) between these levels on both sides: L3r, 45+/-6 mm*; L4r, 48+/-7 mm; L5r, 50+/-6 mm*; L3l, 44+/-5 mm**; L4l, 47+/-6 mm; L5l, 50+/-6 mm**. In patients, 25 of 28 ultrasound-guided needles were placed accurately, with the remaining three closer than 5 mm to the radiologically defined target point.

Conclusion: Ultrasound guidance seems to be a promising new technique with clinical relevance and the potential to increase practicability while avoiding radiation in lumbar facet nerve block.
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http://dx.doi.org/10.1097/00000542-200405000-00028DOI Listing
May 2004
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