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Biomedical subjects

U Büchler

Publications and source records attributed to U Büchler.

At least 19 recordsLinked to original sources
PubMed2005

Anatomy of the proximal cutaneous perforator vessels of the gracilis muscle.

An anatomic study was performed to analyse the proximal perforator vessels of the gracilis musculocutaneous flap. Twenty-three cadaver legs preserved by the method of Thiel were carefully dissected 24h after the proximal vascular pedicle was injected with a red silicone mass. Nine additional cadaver legs were injected with ink, to visualise the skin area supplied by the proximal perforators, respectively, clarified by a modified Spalteholz technique to demonstrate the anatomic course of the perforators. A considerable variation in numbers and localisation of proximal cutaneous perforators was found. One to four perforators were seen within an area of 6 x 6 cm(2) at the entrance of the main pedicle into the proximal gracilis muscle. Their external diameter ranged from 0.5 to 1.0 mm. The ink-injections showed an oval shaped angiosome with a mean surface of 88 cm(2) at the level of the proximal gracilis pedicle. We conclude from this anatomic study, that a cutaneous flap based on the medial circumflex femoral gracilis perforators can be harvested by experienced hands bearing in mind the unpredictable perforator-anatomy.

Arteries↗
PubMed2002

[How reliable is the posterior interosseous artery island flap? A review of 88 patients].

The distally-based, reverse posterior interosseous flap can be used to reconstruct soft-tissue defects in the region of the hand, provided there is an intact anastomotic network of the posterior and anterior interosseous system at the wrist. Between 1986 and 2000, 88 flap procedures were planned. Anatomical variations were recorded in 21 patients (24 %), in five of which the flap could not be harvested. In the remaining 16 patients, flap dissection was more difficult due to anatomical variations. There was a complication rate of 23 %, including haematoma, congestion, infection or technical errors, which resulted in flap necrosis of variable degrees in 11 patients (13 %). In case of haematoma, flap loss could be reduced by early revision surgery. There was no statistical correlation between anatomical variations and complications or flap loss. Secondary flap corrections, including defatting and remodelling, were commonly performed in due course. Knowing the limitations of the posterior interosseous flap, fasciocutaneous flaps are considered ideal to reconstruct soft-tissue defects or contractures of the thumb web and the dorsal hand because of good tissue matching. Fascial flaps are a good option for palmar defects or to wrap around neurolyzed nerves.

Adolescent↗
PubMed2001

The evolutionary split of Pinaceae from other conifers: evidence from an intron loss and a multigene phylogeny.

The second intron in the mitochondrial gene nad1 was surveyed using PCR, DNA sequencing, or Southern hybridization in 323 species (313 genera, 212 families) of seed plants. The intron was absent in all 22 species (22 genera, 8 families) of non-Pinaceae conifers studied, in Welwitschia mirabilis, and in seven angiosperms. Whereas absence of the intron in seven angiosperms and Welwitschia is likely due to seven independent losses when evaluated against the recently published multigene phylogenies, the lack of the intron in all non-Pinaceae conifers can be best explained by a single loss. These data suggest that the non-Pinaceae conifers represent a monophyletic group. We also conducted a phylogenetic analysis of seed plants using a combined data set of the partial exon and intron sequences of nad1 generated from this study and published sequences of mitochondrial cox1 and small subunit (SSU) rDNA, chloroplast rbcL, and nuclear 18S rDNA. The results supported the split of conifers into two groups: Pinaceae and non-Pinaceae conifers. The Gnetales were sister to Pinaceae, in agreement with the conclusion from other recent molecular phylogenetic studies that refute the anthophyte hypothesis.

Base Sequence↗
PubMed2001

Tandem repeats in plant mitochondrial genomes: application to the analysis of population differentiation in the conifer Norway spruce.

Mitochondrial DNA, widely applied in studies of population differentiation in animals, is rarely used in plants because of its slow rate of sequence evolution and its complex genomic organization. We demonstrate the utility of two polymorphic mitochondrial tandem repeats located in the second intron of the nad1 gene of Norway spruce. Most of the size variants showed pronounced population differentiation and a distinct geographical distribution. A GenBank search revealed that mitochondrial tandem repeats occur in a broad range of plant species and may serve as a novel molecular marker for unravelling population processes in plants.

Cycadopsida↗
PubMed2001

Haplotype variation in a mitochondrial tandem repeat of Norway spruce (Picea abies) populations suggests a serious founder effect during postglacial re-colonization of the western Alps.

Populations from 13 elevational transects of Norway spruce [Picea abies (L.) Karst] across the Alpine range were sampled to elucidate the geographical pattern of genetic variation in relation to postglacial re-colonization and to study elevational effects on haplotypic diversity. We assessed fragment length variation in a tandem repeat region of the mitochondrial (mt) nad1 intron 2. This maternally inherited genetic marker is suited to infer migration as it is dispersed by seed only. A total of 10 haplotypes was found, most of which were due to repeat copy number variation. An analysis of molecular variance (amova) showed that overall population differentiation was high (F(ST)=0.41), and it revealed a significant differentiation between monomorphic western and moderately to highly variable eastern Alpine populations. This phylogeographic pattern may be explained by a founder effect during postglacial re-colonization. An early arriving haplotype, assumed to originate from a western Carpathian refugium, could expand into suitable habitats, reducing the chances for establishment of subsequently arriving haplotypes. On the other hand, the high variation in populations within an Italian transect of the south-eastern Alps may be the consequence of merging migration pathways from and close distance to putative glacial refugia, most likely those assumed in the Carpathian mountains and on the Balkan peninsula or possibly in the central plains of Italy. An effect of elevation on haplotypic diversity was not evident, though a low, but significant, partition of total genetic variation was attributed to among-population variation in one Italian transect. Various factors, such as vertical seed dispersal and forest management, may account for blurring an otherwise established pattern of genetic variation on a small geographical scale.

Analysis of Variance↗
PubMed2001

Chloroplast microsatellites and mitochondrial nad1 intron 2 sequences indicate congruent phylogenetic relationships among Swiss stone pine (Pinus cembra), Siberian stone pine (Pinus sibirica), and Siberian dwarf pine (Pinus pumila).

We studied the phylogenetic relationships among the three stone pine species, Pinus cembra, P. sibirica, and P. pumila, using chloroplast microsatellites and mitochondrial nad1 intron 2 sequences. The three chloroplast microsatellite loci combined into a total of 18 haplotypes. Fourteen haplotypes were detected in 15 populations of P. cembra and one population of P. sibirica, five of which were shared between the two species, and the two populations of P. pumila comprised four species-specific haplotypes. Mitochondrial intron sequences confirmed this grouping of species. Sequences of P. cembra and P. sibirica were identical, but P. pumila differed by several nucleotide substitutions and insertions/deletions. A repeat region found in the former two species showed no intraspecific variation. These results indicate a relatively recent evolutionary separation of P. cembra and P. sibirica, despite their currently disjunct distributions. The species-specific chloroplast and mitochondrial markers of P. sibirica and P. pumila should help to trace the hybridization in their overlapping distribution area and to identify fossil remains with respect to the still unresolved postglacial re-colonization history of these two species.

Base Sequence↗
PubMed2001

Molecular identification of fine roots of trees from the Alps: reliable and fast DNA extraction and PCR-RFLP analyses of plastid DNA.

Fine roots of trees are intensively used as indicators to assess soil alterations, e.g. those owing to atmospheric inputs of acidifying substances, but their identification to species with morphological criteria is difficult. In this study, we established molecular techniques in order to identify fine roots of the 30 most common tree species of the Alps. We developed a protocol for efficient isolation of DNA from fine roots with extraction of DNA in the presence of polyvinylpyrrolidone (PVP) and polyvinylpolypyrrolidone (PVPP). The trnL (UAA) intron of plastid DNA was used as a marker for fine root identification. We amplified and sequenced this intron with plant universal primers. The size of the sequences ranged from 444 to 672 bp. A synoptic key for species identification was designed on the basis of restriction fragment patterns predicted from sequence data. Using the restriction enzyme TaqI as key enzyme, and where necessary HinfI, RsaI and CfoI, 16 taxa, including Picea abies, Larix decidua, Abies alba, and Fagus sylvatica, the dominant tree species of the Alpine region could be identified by agarose gel electrophoresis of restriction fragments. Fourteen taxa could be identified to the genus level, among them Quercus, Salix and Populus species. In a field study, conducted in a 20 x 30 m plot of a mixed forest with five tree species, fine roots of 43 out of 46 samples were identified and their distributions were mapped. These results demonstrate the utility of our DNA extraction method and of the trnL intron for the identification of fine tree roots.

DNA, Plant↗
PubMed2001

Species-specific detection of Lobaria pulmonaria (lichenized ascomycete) diaspores in litter samples trapped in snow cover.

The foliose lichen Lobaria pulmonaria has suffered a substantial decline in central and northern Europe during the twentieth century and is now considered to be critically endangered in many European lowland regions. Based on demographic studies, it has been proposed that under the present environmental conditions and forest management regimes, dispersal of diaspores and subsequent establishment of new thalli are insufficient to maintain the remnant small lowland populations. Chances of long-term survival may therefore be reduced. The data and analytical power of these demographic studies are limited. Since lichen diaspores show very few species-specific morphological characteristics, and are therefore almost indistinguishable, the accurate assessment of diaspore flux would be a fundamental first step in better understanding the life cycle of L. pulmonaria. Here we present a new molecular approach to investigate the dispersal of L. pulmonaria diaspores in its natural environment by specifically identifying small amounts of DNA in snow litter samples at varying distances from known sources. We used a species-specific polymerase chain reaction (PCR) primer pair to amplify the ribosomal internal transcribed spacer region (ITS rDNA) and a sensitive automated PCR product detection system using fluorescent labelled primers. We detected considerable amounts of naturally dispersed diaspores, deposited as far as 50 m away from the closest potential source. Diaspores were only found in the direction of the prevailing wind. Diaspore deposition varied from 1.2 diaspores per m(2) per day at 50 m distance from the source to 15 diaspores per m(2) per day at 1 m distance. The method described in this paper opens up perspectives for studies of population dynamics and dispersal ecology mainly in lichenized ascomycetes but also in other organisms with small, wind-dispersed diaspores.

Lichens↗
PubMed2001

Rigid internal fixation of basilar fractures of the proximal phalanges by cancellous bone grafting only.

Ten patients with 13 basilar metaphyseal impaction fractures of the proximal phalanges of the fingers were treated with "rigid internal fixation" by bone grafting alone. When retrospectively reviewed at a mean follow-up of 32 months, bone healing had occurred without any relevant secondary displacement of the fracture fragments. The final ranges of motion were good and return to work was quicker than expected.

Adolescent↗
PubMed1998

Chronic post-traumatic radial instability of the metacarpophalangeal joint of the finger. Long-term results of ligament reconstruction.

Chronic painful post-traumatic instability of the radial collateral ligament complex of the metacarpophalangeal joint of a finger was treated by tendon graft reconstruction in 24 patients. Seventeen patients (20 joints) were available for a retrospective study at a mean follow-up time of 105 months. Eighty percent of the joints showed excellent or good results, with relief of pain, return of adequate stability, a near normal range of motion and absence of degenerative changes.

Chronic Disease↗
PubMed1998

[Is panarthrodesis the gold standard in wrist joint surgery?].

In order to determine the value of panarthrodesis, 109 cases have been reviewed. Relevant complications occurred in 36%, whereof 20 were serious entailing reoperations. The procedure was most rewarding in patients with inflammatory arthritis which were mostly painfree and regained full strength, whereas in cases following trauma and avascular necrosis of the lunate, only 56% were painfree, and only 6% achieved contralateral strength. In comparison with 52 cases which had undergone procedures preserving wrist motion, the results were not different with regard to pain relief and strength, whereas in the patients treated accordingly, a functional amount of wrist motion could be preserved.

Adolescent↗
PubMed1997

The dorsal middle phalangeal finger flap. Mid-term results of 43 cases.

The dorsal middle phalangeal finger (DMF) flap is a (neuro)vascular island flap based on one palmar proper digital artery, its venae comitantes (and/or a separate dorsal vein) and the dorsal branch(es) of the palmar digital nerve. The main nerve supply of the donor finger is left undisturbed. The flap may be raised on a short antegrade, long antegrade or a retrograde pedicle, and used as a free, arterial and/or venous flow-through or neurovascular flap. In a prospective study (mean follow-up of 50 months), the results of 43 DMF flaps were analysed. All flaps survived, retained patency of their vascular pedicles and fulfilled their goals. Neurovascular flaps provided sensate coverage at the S3+ level with static 2-point discrimination values of about 10 mm. Dissection between the proper digital nerve and the rest of the neurovascular bundle induced a 5% incidence of cold intolerance and a 12% occurrence of S3+ hypaesthesia. Advantages, drawbacks and indications of DMF flaps are outlined.

Adolescent↗
PubMed1997

Long-term results of radioscapholunate fusion following fractures of the distal radius.

Fifteen patients with radioscapholunate (RSL) fusion for traumatic lesions of the radiocarpal junction, whose short-term results have been previously reported, were reassessed after an average follow-up time of 8 years. Five patients had undergone wrist fusion because of non-union or early progressive arthritis. Of the ten wrists with retained mobility, eight continued to function satisfactorily. Two wrists were painful for reasons other than secondary midcarpal arthritis. Patient satisfaction was comparable in both groups with the wrist score better for wrists with residual motion. The survival of RSL partial wrist fusion corresponded inversely with the number of preceding operations and the range of motion before partial fusion. Secondary midcarpal arthritis, if present, arose early and was well tolerated. Failures were strongly linked to technical mistakes and complications.

Adult↗