Persistence of arctic-alpine flora during 24,000 years of environmental change in the Polar Urals.

Plants adapted to extreme conditions can be at high risk from climate change; arctic-alpine plants, in particular, could "run out of space" as they are out-competed by expansion of woody vegetation. Mountain regions could potentially provide safe sites for arctic-alpine plants in a warmer climate, but empirical evidence is fragmentary. Here we present a 24,000-year record of species persistence based on sedimentary ancient DNA (sedaDNA) from Lake Bolshoye Shchuchye (Polar Urals). We provide robust evidence of long-term persistence of arctic-alpine plants through large-magnitude climate changes but document a decline in their diversity during a past expansion of woody vegetation. Nevertheless, most of the plants that were present during the last glacial interval, including all of the arctic-alpines, are still found in the region today. This underlines the conservation significance of mountain landscapes via their provision of a range of habitats that confer resilience to climate change, particularly for arctic-alpine taxa.

An AFLP clock for absolute dating of shallow-time evolutionary history--too good to be true?

A major drawback of Amplified Fragment Length Polymorphisms (AFLP) as genetic makers for phylogeographic studies is their lack of a temporal dimension. In a recent publication in Molecular Ecology, Kropf et al. (2009) proposed a molecular clock for AFLP. In this comment we evaluate the proposed approach both theoretically and empirically. A linear increase with time is a prerequisite to use a genetic distance as molecular clock. Testing the relationship between genetic distance and time in the data of Kropf et al. (2009) for linearity revealed that the relationship was in fact not linear for their pooled data, as well as for one of the three species analyzed. Also, the relationship was not linear in two new species, where divergence times could be inferred from macrofossils. When applying the proposed molecular clock to data from eight species, dates obtained were plausible in some cases, but very improbable in others. The suggested genetic distance was also influenced by intrapopulation genetic diversity, leading to a potential bias. In the future, investigations of AFLP mutation rates combined with phylogeographic modelling may contribute to adding a time scale to the understanding of AFLP data.

Families in space: relatedness in the Barents Sea population of polar bears (Ursus maritimus).

The kin structure and dispersal pattern of polar bears (Ursus maritimus) of the Barents Sea was investigated during the spring mating season using two complementary approaches. First, individual genotypes based on the analyses of 27 microsatellite loci of 583 polar bears were related to field information gathered from 1146 bears in order to reconstruct the animals' pedigrees and to infer geographical distances between adult bears of different relatedness categories. According to the data, the median natal dispersal distance of the male animals was 52 km while that of the females was 93 km. Second, the relatedness of pairs of adult bears was estimated and correlated to the geographical distance between them. The female dyads had a much stronger kin structure than the male dyads. The 'pedigree approach' revealed a male kin structure which could not be detected using the 'relatedness approach'. This suggests that, on a broader scale, effective dispersal is slightly male biased. Despite fidelity to natal areas, male-mediated gene flow may nevertheless prevent genetic differentiation. Males might occasionally shift their home range which could therefore lead to a male-biased breeding dispersal. Our results showed that a nonterritorial species such as the polar bear that has a high dispersal potential, lives in a highly unstable environment and migrates seasonally is still able to exhibit a distinct kin structure during the mating season.

Statistical analysis of amplified fragment length polymorphism data: a toolbox for molecular ecologists and evolutionists.

Recently, the amplified fragment length polymorphism (AFLP) technique has gained a lot of popularity, and is now frequently applied to a wide variety of organisms. Technical specificities of the AFLP procedure have been well documented over the years, but there is on the contrary little or scattered information about the statistical analysis of AFLPs. In this review, we describe the various methods available to handle AFLP data, focusing on four research topics at the population or individual level of analysis: (i) assessment of genetic diversity; (ii) identification of population structure; (iii) identification of hybrid individuals; and (iv) detection of markers associated with phenotypes. Two kinds of analysis methods can be distinguished, depending on whether they are based on the direct study of band presences or absences in AFLP profiles ('band-based' methods), or on allelic frequencies estimated at each locus from these profiles ('allele frequency-based' methods). We investigate the characteristics and limitations of these statistical tools; finally, we appeal for a wider adoption of methodologies borrowed from other research fields, like for example those especially designed to deal with binary data.

Pleistocene colonization of afro-alpine 'sky islands' by the arctic-alpine Arabis alpina.

The afro-alpine region comprises the high mountains of Ethiopia and tropical East Africa, which represent biological 'sky islands' with high level of endemism. However, some primarily arctic-alpine plants also occur in the afro-alpine mountains. It has been suggested that these plants are Tertiary relicts, but a recent worldwide study of Arabis alpina suggests that this species colonized the region twice during the Pleistocene. Here we investigate the detailed colonization history of A. alpina in the afro-alpine region based on chloroplast DNA sequences from 11 mountain systems. The results confirm the twice-into-Africa scenario. The Asian lineage is confined to the mountains closest to the Arabian Peninsula, on opposite sides of the Rift Valley (Simen Mts and Gara Muleta in Ethiopia), suggesting long-distance dispersal of this lineage. The African lineage is divided into two phylogeographic groups with distinct geographic distribution. The observed pattern is consistent with isolation of the African lineage in at least two interglacial refugia, located on separated highlands, followed by range expansion in cooler period(s), when the afro-alpine habitat extended further down the mountains. Several long-distance dispersal events, also across the Rift Valley, are suggested by single haplotypes observed outside the area occupied by the phylogeographic groups they belonged to.

[Orbital foreign bodies -- diagnostics, therapy and management]. / Orbitafremdkörper -- Diagnostik und Differenzialtherapie.

BACKGROUND: Orbital foreign bodies constitute an interdisciplinary challenge, diagnosis being especially difficult because of inconspicuous entrance orifices. Indication for the removal of an orbital foreign body has always to be decided upon individually taking into account the benefits and risks resulting from an operation. The latter is particularly indicated if there are acute and chronic functional restrictions or inflammatory reactions either present or to be expected. The objective of our study was to produce systematic guidelines concerning the therapeutic procedure of dealing with orbital foreign bodies with a view to a benefit-risk assessment. PATIENTS AND METHODS: Over the last ten years ten patients with an orbital foreign body were treated in our Department, four of them requiring acute attention. CTs were taken of all patients. Only in one case additional MRTs were produced. Eight out of ten patients underwent operation, of which seven resulted in a complete removal of the foreign body. In the case of two patients we decided against an operation after interdisciplinary consultation. RESULTS: In our view the imaging--providing diagnostics by means of computer tomography is the most promising method for determining a foreign body in the orbit. Decision for an operative removal of a foreign body was invariably taken interdisciplinary in cooperation with an ophthalmologist. Surgical approach was chosen in accordance with the localisation of the foreign bodies. None of the patients suffered from a loss of vision or a restriction of functions as a result of the operation. CONCLUSIONS: In the indication the foreign material is of essential importance. Orbital foreign bodies that have been present in the tissue for a longer time can be allowed to stay, unless loss of functions are progressive. Loss of vision always being a consequence of the initial trauma.

[Lacrimal system injuries -- primary and secondary surgical care]. / Verletzungen der ableitenden Tränenwege -- primäre und sekundäre operative Versorgung.

BACKGROUND: Canalicular lacerations can be the result of sharp or blunt trauma as well as burns of the facial region. The nasolacrimal duct may become obstructed as an after-effect of naso-orbital trauma. MATERIAL AND METHODS: Main principles of surgical repair of the lacrimal system are reviewed with regard to the outcome of our own patients compared with the literature. RESULTS: Success rates in the primary repair of traumatic injuries of canalicular system are about 70 to 82 %. 14 of 20 patients who were managed between 1976 and 1980 in our department were cured permanently. 55 of 272 secondary reconstructions of canalicular obstructions (1976 - 1997) were caused by trauma. Conjunctivodacryocystorhinostomy with polyethylene or silicone tubes (1978 - 1999, n = 37, 21 traumatic) had success rates of 61 % and 72 %, respectively. 11 (4.8 %) of 228 dacryocystorhinostomies (1991 - 2000) were necessary as a result of traumatic injuries and achieved a success rate of 87.5 %. CONCLUSIONS: Canalicular lacerations need urgent primary repair with silicone intubation and special heed to the medial canthal tendon. The success rate of secondary reconstructions of traumatically caused tear-duct system obstructions depends on the microsurgical techniques that were used.

[The use of intracorneal rings in penetrating keratoplasty]. / Zum Einsatz von Nahtspannringen bei perforierenden Keratoplastiken.

BACKGROUND: The visual rehabilitation after penetrating keratoplasty (PKP) is affected by postoperative corneal astigmatism. Up to now studies were focused on different trephine systems as well as the suture techniques. A new option for reducing postoperative corneal astigmatism could be the implantation of an intracorneal ring. PATIENTS AND METHODS: Over a period of 2 years we implanted in 20 patients, who were suffering from keratoconus, Fuchs' dystrophy or bullous keratopathy, an 8-mm cobalt-molybdenum-titanium intracorneal ring in a prospective clinical trial. We used the guided trephine system (GTS) for preparation and a 10-0 nylon double running suture. The mean follow-up period was 16.2 months. A control group of 20 additional patients who underwent PKP was randomized. Topographic astigmatism as well as the spherical equivalent was evaluated after 1, 3, 6 and 12 months, respectively. RESULTS: Although a lower topographic astigmatism in the intracorneal ring group was reached 12 months postoperatively (3.0 dptr., SD 1.2 versus 4.0 dptr., SD 1.8) no statistical significance was found. The spherical equivalent in that group was lower during the complete evaluation period with a hyperopization in both groups as well. We did not see any immunological reactions caused by the ring. CONCLUSIONS: Whether the intracorneal ring could be a useful addition to PKP is not yet clear. Therefore more patients need to be enrolled and further studies established.

Genetic structure of Siberian lemmings (Lemmus sibiricus) in a continuous habitat: large patches rather than isolation by distance.

In a continuous habitat, restricted dispersal and local genetic drift are likely to create a pattern of increasing genetic differentiation with distance. Here, we describe the genetic structure of Siberian lemming (Lemmus sibiricus) populations in a continuous tundra habitat on the western coast of the Taimyr Peninsula, in order to determine the spatial scale at which genetic differentiation and isolation by distance occur. Sampling was carried out at three different geographical scales: (1) a continuous 11 km transect; (2) localities 10-30 km apart; and (3) two localities at 300 and 600 km from the main study area. Two types of genetic markers were used: partial sequences of the mitochondrial DNA control region and four microsatellite loci. On this basis the study populations were genetically quite homogeneous within patches extending over 8 km or more. Contrary to theoretical predictions, no pattern of isolation by distance among patches could be identified. This observation was interpreted as representing populations in migration-drift disequilibrium after a recent major mixing event. The lack of concordance between mtDNA haplotype phylogeny and the geographical distribution of haplotypes supported this interpretation. Spatial autocorrelation among individual genotypes on a local scale was weak and observed only in females, indicating a considerable amount of mostly male-mediated gene flow. Average gene flow per generation was estimated to be in the range of several hundred metres.

Spatial structure of lemming populations (Dicrostonyx groenlandicus) fluctuating in density.

The pattern and scale of the genetic structure of populations provides valuable information for the understanding of the spatial ecology of populations, including the spatial aspects of density fluctuations. In the present paper, the genetic structure of periodically fluctuating lemmings (Dicrostonyx groenlandicus) in the Canadian Arctic was analysed using mitochondrial DNA (mtDNA) control region sequences and four nuclear microsatellite loci. Low genetic variability was found in mtDNA, while microsatellite loci were highly variable in all localities, including localities on isolated small islands. For both genetic markers the genetic differentiation was clear among geographical regions but weaker among localities within regions. Such a pattern implies gene flow within regions. Based on theoretical calculations and population census data from a snap-trapping survey, we argue that the observed genetic variability on small islands and the low level of differentiation among these islands cannot be explained without invoking long distance dispersal of lemmings over the sea ice. Such dispersal is unlikely to occur only during population density peaks.

[Prognosis of conjunctivo-dacryocystorhinostomy. Modification with different implant materials]. / Prognose der Konjunktivodakryozystorhinostomie. Modifikationen mit unterschiedlichen Implantatmaterialien.

BACKGROUND: In cases of total canalicular occlusion or the total absence of the lacrimal apparatus the functional restoration requires the repair of a newly created lacrimal system. The intraoperatively reestablisted lacrimal drainage from the conjunctival sac will be maintained by a plastic tube. Beside other criteria the influence of the used inserted materials polyethylene or silicone should be evaluated. PATIENTS AND METHODS: From 9/1978 to 2/1999 we have been treated and consecutive documented 37 cases of conjunctivodacryocystorhinostomy and its modifications in 36 patients (1mal both eyes). The patients (22 men, 14 women) ranged in age from 9-76 years (mean age of 35.2 years). In a retrospective review results were compared for the following two groups based on the type of used plastic tube: group I: (n = 23); insertion of a polyethylene tube (from 1976-1990); group II: (n = 14) insertion of a silicone tube (from 1991-1998). RESULTS: Causes of lacrimal drainage system obstruction were trauma (n = 21), malformation (n = 8), chronic inflammation (n = 5) and tumor (n = 2). The following different surgical techniques were performed: conjunctivodacryocystorhinostomy (cdr, n = 23), conjunctivodacryocystostomy (cd, n = 10) and conjunctivorhinostomy (cr, n = 4), (right eye: n = 21, left eye: n = 16). In group I 14 of 23 operations (61%) had successful functional results, in group II 10 of 14 operations (72%), respectively. The polyethylene tubes on the average were maintained for 15 months after surgery (4mal spontaneous removal) and the silicone tubes for 12 months, respectively (4mal spontaneous removal). CONCLUSION: Traumatic disturbance and congenital defects of canaliculi and surrounding tissue require in the case of any symptoms the surgical reconstruction of the lacrimal pathway. With the introduction of the silicone tube the success rate could be further advanced.

Phylogeography and mitochondrial DNA (mtDNA) diversity in North American collared lemmings (Dicrostonyx groenlandicus).

Variation in the nucleotide sequence of the mitochondrial control region (250 bp) and the cytochrome b region (870 bp) was examined in collared lemmings (Dicrostonyx groenlandicus) from 19 localities in northern Alaska and the Canadian Arctic. The division of D. groenlandicus in two phylogeographical groups with limited divergence across the Mackenzie River is consistent with the separation of this species in more than one refugial area located to the northwest of the Laurentide ice sheet during the last glaciation. Populations of D.groenlandicus from formerly glaciated areas are no less variable than those in nonglaciated areas. Instead, the low intrapopulation and intraregional diversity estimates in D. groenlandicus are probably a result of regional bottleneck events due to range contractions during Holocene warming events. These results are consistent with findings previously reported on collared lemmings (D. torquatus) from the Eurasian Arctic.

Comparison of triazolam, diazepam, and placebo as outpatient oral premedication for endodontic patients.

Triazolam and diazepam were compared as oral antianxiety agents in a randomized double-blind, placebo-controlled clinical study of 79 endodontic patients with elevated anxiety regarding endodontic treatment. Patients who scored > or = 10 on the Corah Dental Anxiety Survey received oral formulations of triazolam (0.25 mg), diazepam (5 mg), or placebo. Before, during, and after the endodontic procedure, patients completed psychomotor tests and anxiety scales, and were evaluated for 24-h postoperative recall. In comparison with diazepam and placebo, triazolam was significantly better for decreased anxiety (p < 0.05), impaired cognitive function (p < 0.05), patients' rating of drug effectiveness (p < 0.05), and amnesia to clinical events (p < 0.02) and pictures (p < 0.03). Diazepam showed similar trends compared with placebo, but to a lesser degree. Diazepam also had a much longer recovery period. No adverse effects were noted with either drug. These findings suggest that orally administered triazolam (0.25 mg) is a safe and more effective anxiolytic agent than diazepam (5.0 mg) for endodontic patients.

Response of patients with coronary artery disease stratified by ejection fraction following short-term training.

The purpose of this study was to investigate the response of patients with ischemic heart disease and varied left ventricular function following 6 weeks of exercise training. We studied the oxygen consumption (VO2), and central hemodynamic and metabolic responses of 14 patients with coronary artery disease (CAD) stratified by left ventricular ejection fraction (EF). There were two groups of patients: normal EF (NEF), EF = 64 +/- 9.9 (mean +/- S.E.M.); n = 7, and diminished EF (DEF), EF = 36 +/- 11.6; n = 7. The patients ranged in age from 42 to 72 years (54.9 +/- 2.2), and were evaluated prior to and then following training. Measures of VO2, cardiac output (Qt) stroke volume (SV), heart rate (HR), exercise duration (XTIME) and intensity (XI), as well as plasma lactate (LA), and the catecholamines epinephrine (E) and norepinephrine (NE) were obtained in response to maximal cycle ergometry. Subjects trained three times per week, 30 min per session, at an intensity equal to 70% of their peak oxygen consumption. Repeated measures analysis of variance (ANOVA) revealed no interaction between groups suggesting a similar training response. Significant post-training changes (P < 0.05) were observed in peak VO2 (VO2peak) NEF, 11.8% increase, (16.0 +/- 1.3 to 17.9 +/- 1.1 ml/kg/min) and DEF, 9.3% increase (15.1 +/- 1.6 to 16.5 +/- 1.2 ml/kg/min); submaximal HR, 4% decrease in the NEF (95.57 +/- 4.58 to 92 +/- 4.43 beats/min) and a 6% decrease in the DEF (107.29 +/- 7.44 to 101.43 +/- 6.77 beats/min); XTIME NEF, 11.2% increase (7.8 +/- 0.57 to 8.67 +/- 0.61 min) and DEF, 16.6% increase (7.3 +/- 0.91 to 8.51 +/- 0.69 min); and XI NEF, 19.2% increase (104.3 +/- 11.3 to 124.3 +/- 12.9 W) DEF, 21.2% increase (94.3 +/- 18.5 to 114.3 +/- 16.9 W), and a 15% decrease in resting NE (350 +/- 26 to 296.9 +/- 19 pg/ml). There were no changes in Qt, SV, LA, E, peak NE or peak HR for either group. These findings suggest short-term endurance training at 70% VO2peak provide the necessary stimulus for individuals with CAD and NEF or DEF to display an improvement in XI, XTIME, and VO2peak. The lack of a significant enhancement in Qt with short-term training may indicate that the mechanism by which both study groups were able to attain significantly higher levels of VO2peak may have been attributable to peripheral mechanisms rather than any alterations in Qt, a central mechanism.

Sodium hypochlorite accident: inadvertent injection into the maxillary sinus.

Sodium hypochlorite was inadvertently injected into the maxillary sinus during root canal treatment of the right maxillary first molar. Sterile water irrigation of the sinus was effected through the palatal canal. The expected sequelae of pain, significant edema, and hemorrhage were not experienced.

Drying periapical films: simplified chairside technique.

A technique is presented for constructing a chairside radiograph dryer to be used after manual developing of films in the operatory. It is of simple construction using household items and common dental laboratory materials.

Successful early streptokinase thrombolysis of aortocoronary vein grafts.

Two patients recently underwent successful early thrombolytic recanalization of thrombosed saphenous vein coronary bypass grafts. This treatment strategy must be weighed against the potential risk of bleeding.