bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mitigation or disturbance? Effects of liming on macroinvertebrate assemblage structure and leaf‐litter decomposition in the humic streams of northern Sweden
Authors: MCKIE B. G. , PETRIN Z. , MALMQVIST B. 
Published: June 2006

Summary

Stream liming can alleviate the effects of anthropogenic acidification but itself constitutes a substantial ecosystem‐level perturbation. Acidity in the humic streams of northern Sweden largely arises from natural causes but liming is extensively practised, with uncertain ecological outcomes.
We investigated macroinvertebrate assemblage structure and leaf‐litter decomposition in seven humic Swedish streams, each of which is limed at a single point using a dosing tower. Grey alder Alnus incana leaves were enclosed in replicate fine (mesh size 0·5 mm) and coarse (10 mm) mesh bags at three locations in each stream: upstream of the dosing tower, in the transitional ‘mixing zone’ immediately downstream of the tower, and at a site further downstream where the lime powder is completely dissolved, with marked changes to water chemistry. Benthic macroinvertebrate assemblages were characterized from each site via five replicate Surber samples.
Alkalinity, pH, conductivity and calcium (Ca) concentrations increased following liming, whereas dissolved organic carbon and aluminium concentrations decreased.
Decomposition in fine mesh bags, primarily mediated by microbes, was positively associated with pH and Ca and was significantly elevated by liming, probably attributable to stimulation of fungal pectin‐degrading enzymes that require Ca as a cofactor.
Decomposition attributable to detritivorous insects (shredders), assessed by subtracting decomposition observed in fine mesh bags from that observed in coarse bags, was reduced following liming, in concert with changes to shredder assemblages. Abundance of large caddisfly shredders declined in limed stream sections, whereas some smaller stoneflies increased in number. Shredder diversity declined following liming during spring. Species evenness fell overall, and richness was reduced in four of six streams.
Synthesis and applications. Water chemistry changes following stream liming in northern Sweden appear to overcompensate for the limited acid deposition observed in the region, with important ecosystem consequences. The potential deleterious impacts of liming need to be balanced against its desired outcomes in regions where acidity is largely attributable to natural causes.
Population structure in a critically endangered arctic fox population: does genetics matter?
Authors: DALÉN L. , KVALØY K. , LINNELL J. D. C. , ELMHAGEN B. , STRAND O. , TANNERFELDT M. , HENTTONEN H. , FUGLEI E. , LANDA A. , ANGERBJÖRN A. 
Published: June 2006

AbstractThe arctic fox (Alopex lagopus) in Scandinavia is classified as critically endangered after having gone through a severe decline in population size in the beginning of the 20th century, from which it has failed to recover despite more than 65 years of protection. Arctic foxes have a high dispersal rate and often disperse over long distances, suggesting that there was probably little population differentiation within Scandinavia prior to the bottleneck. It is, however, possible that the recent decline in population size has led to a decrease in dispersal and an increase in population fragmentation. To examine this, we used 10 microsatellite loci to analyse genetic variation in 150 arctic foxes from Scandinavia and Russia. The results showed that the arctic fox in Scandinavia presently is subdivided into four populations, and that the Kola Peninsula and northwest Russia together form a large fifth population. Current dispersal between the populations seemed to be very low, but genetic variation within them was relatively high. This and the relativeFSTvalues among the populations are consistent with a model of recent fragmentation within Scandinavia. Since the amount of genetic variation is high within the populations, but the populations are small and isolated, demographic stochasticity seems to pose a higher threat to the populations’ persistence than inbreeding depression and low genetic variation.
Gregariousness and protandry promote reproductive insurance in the invasive gastropod Crepidula fornicata: evidence from assignment of larval paternity
Authors: DUPONT L. , RICHARD J. , PAULET Y‐M. , THOUZEAU G. , VIARD F. 
Published: June 2006

AbstractAccording to the size‐advantage hypothesis, protandric sequential hermaphroditism is expected when the increase in reproductive success with age or size is small for males but large for females. Interestingly, some protandrous molluscs have developed gregarious strategies that might enhance male reproductive success but at the cost of intraspecific competition. The gastropod Crepidula fornicata, a European invading species, is ideal for investigating mating patterns in a sequential hermaphrodite in relation to grouping behaviour because individuals of different size (age) live in perennial stacks, fertilization is internal and embryos are brooded. Paternity analyses were undertaken in stacks sampled in three close and recently invaded sites in Brittany, France. Paternity assignment of 239 larvae, sampled from a set of 18 brooding females and carried out using five microsatellite loci, revealed that 92% of the crosses occurred between individuals located in the same stack. These stacks thus function as independent mating groups in which individuals may reproduce consecutively as male and female over a short time period, a pattern explained by sperm storage capacity. Gregariousness and sex reversal are promoting reproductive insurance in this species. In addition, females are usually fertilized by several males (78% of the broods were multiply sired) occupying any position within the stack, a result reinforcing the hypothesis of sperm competition. Our study pointed out that mating behaviours and patterns of gender allocation varied in concert across sites suggesting that multiple paternities might enhance sex reversal depending on sperm competition intensity.
The Pelican Cancer Foundation and The English National MDT‐TME Development Programme
Authors: Jessop J. , Beagley C. , Heald R. J. 
Published: June 2006

AbstractThe formation of The Pelican Cancer Foundation in 2000 was based around the pioneering work of Professor Bill Heald and colleagues, and the development of Total Mesorectal Excision (TME) for rectal cancer. A series of surgical workshops in Scandinavia in the mid 1990s and, later, six further workshops in the Trent region culminated in the commissioning of the fully multidisciplinary National MDT‐TME Development Programme by the National Cancer Director, Professor Mike Richards, in March 2003.
Emerging therapies for rectal cancer
Authors: Chua Y. J. , Cunningham D. 
Published: June 2006

AbstractPreoperative treatment with either short‐course radiotherapy or chemo‐radiotherapy (CRT) is used routinely in some centres to reduce local recurrence rates in patients with operable rectal cancer prior to optimal surgery. However, there is a need for new treatment strategies to further improve the outcomes of these patients, particularly with regard to survival. Advances in the treatment of metastatic disease, such as the use of combination chemotherapy with oxaliplatin and irinotecan, and the targeted agents bevacizumab and cetuximab, have led to clinical research into alternative radio‐sensitizers during CRT and the novel use of neo‐adjuvant (preoperative) chemotherapy prior to preoperative CRT and surgery. Whilst these remain experimental, it is likely that these will serve as a platform for developing an expanded range of treatment options so that clinicians will be better able to tailor treatment to the needs of different patients.
Assessment and management of the complete clinical response of rectal cancer to chemoradiotherapy
Authors: Habr‐Gama A. 
Published: June 2006

AbstractPreoperative chemoradiotherapy is considered by many as the preferred treatment strategy for distal rectal cancer. The observation of complete tumour regression has led to the proposition of nonoperative management of selected patients with complete clinical response (cCR) following treatment. We present results for the treatment of distal rectal cancer during 1991–2005. We have outlined the issues concerning adequate tumour assessment, the definition of complete response, and the advantages and disadvantages of conservative or surgical resection in patients with clinical and radiological evidence of cCR.
Laparoscopic surgery for colorectal cancer
Authors: Kienle P. , Weitz J. , Koch M. , Büchler M. W. 
Published: June 2006

AbstractTraditionally open surgical resection has been recommended for colorectal tumours, but recently, laparoscopic surgery has gained popularity. This review summarizes the published data on laparoscopic colorectal cancer surgery with emphasis on recently published trials. For colon cancer laparoscopic resection appears to be associated with the same outcome as open surgery. However, whilst short‐term outcome was better in the laparoscopic group in most of the randomized trials, when comparing laparoscopic with fast‐track open surgery, no differences could be demonstrated in a randomized control trial. For rectal cancer the data are less clear. It seems that it may be feasible to resect at least small rectal cancers laparoscopically. Clearly the role of the laparoscopic technique needs to be better defined in rectal cancer. It has been well documented that short‐ and long‐term outcome of colorectal cancer surgery depends on the quality and experience of the team treating the patient. Therefore, the major future challenge in laparoscopic colorectal cancer surgery will be to provide and structure adequate training and introduce quality control measures.
Pathological assessment of rectal carcinoma after preoperative therapy
Authors: Wotherspoon A. C. 
Published: June 2006

AbstractIncreasingly neoadjuvant therapy is being used to improve outcomes in patients with rectal carcinoma in which the circumferential resection margins are considered to be at risk for involvement if primary surgery were to be undertaken. Assessment of the response to this approach relies on radiological examination, particularly magnetic resonance imaging (MRI) studies. Following definitive surgery, careful histological examination allows full assessment of the tumour response to these preoperative approaches. Histological examination requires careful fixation, examination of the entire area occupied by the tumour prior to down‐staging and careful lymph node harvesting. Adequate fixation helps in these endeavours and the lymph node harvest appears to be unaffected by neoadjuvant chemo‐ or radiotherapy. Correlation between preoperative assessment of response by MRI and the subsequent histological assessment is close, but the presence of isolated residual neoplastic glands in a post‐treatment fibrotic stroma is impossible to detect prior to resection. The clinical significance of these microscopic foci remains uncertain, particularly in view of the prolonged tumour doubling time associated with colorectal adenocarcinoma. The preoperative discussion with the patient requires a synthesis of their own scan results and the experience of detailed clinico‐pathological studies. While MRI frequently predicts the presence or absence of residual tumour the possibility of under‐staging remains and this is of crucial importance if a ‘watch and wait’ policy is to be adopted following apparent complete clinical and radiological remission. The significance of potential residual microscopic disease in patients with apparent radiological complete remission needs further investigation but may need to be interpreted in individual patients in the context of overall life‐expectancy.
Four‐bar linkage modelling in teleost pharyngeal jaws: computer simulations of bite kinetics
Authors: Grubich Justin R. , Westneat Mark W. 
Published: June 2006

AbstractThe pharyngeal arches of the red drum (Sciaenops ocellatus) possess large toothplates and a complex musculoskeletal design for biting and crushing hard prey. The morphology of the pharyngeal apparatus is described from dissections of six specimens, with a focus on the geometric conformation of contractile and rotational elements. Four major muscles operate the rotational 4th epibranchial (EB4) and 3rd pharyngobranchial (PB3) elements to create pharyngeal bite force, including the levator posterior (LP), levator externus 3/4 (LE), obliquus posterior (OP) and 3rd obliquus dorsalis (OD). A biomechanical model of upper pharyngeal jaw biting is developed using lever mechanics and four‐bar linkage theory from mechanical engineering. A pharyngeal four‐bar linkage is proposed that involves the posterior skull as the fixed link, the LP muscle as input link, the epibranchial bone as coupler link and the toothed pharyngobranchial as output link. We used a computer model to simulate contraction of the four major muscles, with the LP as the dominant muscle, the length of which determined the position of the linkage. When modelling lever mechanics, we found that the effective mechanical advantages of the pharyngeal elements were low, resulting in little resultant bite force. By contrast, the force advantage of the four‐bar linkage was relatively high, transmitting approximately 50% of the total muscle force to the bite between the toothplates. Pharyngeal linkage modelling enables quantitative functional morphometry of a key component of the fish feeding system, and the model is now available for ontogenetic and comparative analyses of fishes with pharyngeal linkage mechanisms.
Microcracks in compact bone: a three‐dimensional view
Authors: Mohsin S. , O’Brien F. J. , Lee T. C. 
Published: June 2006

AbstractMicrocracks have been implicated in the loss of bone quality for osteoporosis. In order to detect and monitor their growth, and to use these data to predict fractures, it is essential to obtain quantitative data regarding their shape in three dimensions. Beam‐shaped bone samples from sheep radii were prepared and stained with fluorochrome dyes and tested in cyclical fatigue under four‐point bending in a servo‐hydraulic fatigue‐testing machine. Samples were tested at a frequency of 30 Hz under load control at a stress range of 100 MPa. Holes were drilled into bone samples and used as reference points for reconstructions. A series of thin longitudinal sections were cut using a sledge macrotome. A two‐dimensional image of each section was examined using an epifluorescence microscope and images transferred to a PC via a CCD low‐light colour video camera. A three‐dimensional image of each microcrack was reconstructed using computer software, and its dimensions measured. Cracks were elliptical in shape, longer in the longitudinal direction and with a mean aspect ratio of 5.5 ± 1.05. The mean (± SD) length and width of labelled microcracks were 488 ± 151 and 88 ± 21 µm, respectively.
Reconstructing impairment of secretory ameloblast function in porcine teeth by analysis of morphological alterations in dental enamel
Authors: Witzel Carsten , Kierdorf Uwe , Dobney Keith , Ervynck Anton , Vanpoucke Sofie , Kierdorf Horst 
Published: June 2006

AbstractWe studied the relationship between the macroscopic appearance of hypoplastic defects in the dental enamel of wild boar and domestic pigs, and microstructural enamel changes, at both the light and the scanning electron microscopic levels. Deviations from normal enamel microstructure were used to reconstruct the functional and related morphological changes of the secretory ameloblasts caused by the action of stress factors during amelogenesis. The deduced reaction pattern of the secretory ameloblasts can be grouped in a sequence of increasingly severe impairments of cell function. The reactions ranged from a slight enhancement of the periodicity of enamel matrix secretion, over a temporary reduction in the amount of secreted enamel matrix, with reduction of the distal portion of the Tomes’ process, to either a temporary or a definite cessation of matrix formation. The results demonstrate that analysis of structural changes in dental enamel allows a detailed reconstruction of the reaction of secretory ameloblasts to stress events, enabling an assessment of duration and intensity of these events. Analysing the deviations from normal enamel microstructure provides a deeper insight into the cellular changes underlying the formation of hypoplastic enamel defects than can be achieved by mere inspection of tooth surface characteristics alone.
Apoptosis during the seasonal spermatogenic cycle of Rana catesbeiana
Authors: Sasso‐Cerri Estela , Cerri Paulo Sérgio , Freymüller Edna , Miraglia Sandra Maria 
Published: June 2006

AbstractIn the bullfrog Rana catesbeiana, testicular weight is constant throughout the year, but the volume densities of germinative and interstitial compartments undergo inverse changes from winter (non‐breeding) to summer (breeding). The occurrence of apoptosis in the seminiferous lobules of bullfrogs was investigated in these two periods using sections stained with haematoxylin and eosin (H&E), the TUNEL (terminal deoxynucleotidyl transferase‐mediated dUTP nick end labelling) method and transmission electron microscopy. TUNEL‐positive cells were observed in the seminiferous lobules, and ultrastructural morphological details confirmed the occurrence of cell death by apoptosis. In summer, the occurrence of several spermatogenic processes (in addition to spermiogenesis and spermiation), and then the overconsumption of Sertoli cell‐derived pro‐survival factors, could be responsible for the increased density of apoptotic cells. Alternatively, the low apoptotic frequency in winter could be related to the constant homeostasis in the germinative compartment given that most lobules are filled with primary spermatocytes. As volume densities of interstitial and germinative compartments undergo inverse seasonal variations through the year, the incidence of apoptosis (in summer) could play a part in controlling the spermatogenic process, maintaining the lobular size when interstitial tissue is maximally developed. In winter, the low apoptotic cell density leads to spermatogenic recrudescence and, thereby, the production of an adequate quantity of spermatozoa for the next breeding period. Thus, apoptosis may participate not only in the maintenance of spermatogenic homeostasis, but also in the cyclical control of the different spermatogenic processes according to seasonal changes of the testicular compartments as a whole.
Dynamic mechanics in the pig mandibular symphysis
Authors: Langenbach G. E. J. , Zhang F. , Herring S. W. , Van Eijden T. M. G. J. , Hannam A. G. 
Published: June 2006

AbstractDuring mastication, various biomechanical events occur at the mammalian jaw symphysis. Previously, these events have been studied in the static environment, or by direct recording of surface bone strains. Thus far, however, it has not been possible to demonstrate directly the forces and torques passing through the symphysis in association with dynamically changing muscle tensions. Therefore, we modified a previously published dynamic pig jaw model to predict the forces and torques at the symphysis, and related these to simulated masticatory muscle tensions, and bite, joint and food bolus forces. An artificial rigid joint was modelled at the symphysis, allowing measurements of the tri‐axial forces and torques passing through it. The model successfully confirmed three previously postulated loading patterns at the symphysis. Dorsoventral shear occurred when the lower teeth hit the artificial food bolus. It was associated with balancing‐side jaw adductor forces, and reaction forces from the working‐side bite point. Medial transverse bending occurred during jaw opening, and was associated with bilateral tensions in the lateral pterygoid. Lateral transverse bending (wishboning) occurred at the late stage of the power stroke, and was associated with the actions of the deep and superficial masseters. The largest predicted force was dorsoventral shear force, and the largest torque was a ‘wishboning’ torque about the superoinferior axis. We suggest that dynamic modelling offers a new and powerful method for studying jaw biomechanics, especially when the parameters involved are difficult or impossible to measure in vivo.
Nature's answer to breaching the skin barrier: an innovative development for amputees
Authors: Pendegrass C. J. , Goodship A. E. , Price J. S. , Blunn G. W. 
Published: June 2006

AbstractThe human body has evolved to maintain homeostasis through the covering of skin and mucous membranes, which separate the internal environment from the harsh and variable external milieu. Few structures naturally penetrate these coverings, and teeth are the only exception in human beings. Attempts to breach these barriers, to develop skin‐ penetrating, bone‐anchored amputation prostheses, can lead to opportunist invasion by microorganisms and subsequent infection, which can jeopardize the life of the individual. There are only a few fascinating examples where the integument of other species is interrupted without such dire consequences, and the deer antler is one such case. Deer antlers are cephalic bony appendages arising from the frontal bones of the skull of the males of most deer species, and are true transient skin‐penetrating structures. Antlers are subject to extreme loading during the rutting season and yet the skin–bone barrier remains intact. Here we show how deer antlers can be used as natural analogues for the successful development of specialized orthopaedic amputation prosthetics. We have used quantitative and qualitative findings from a study of the morphology of deer antlers to develop a device that mimics their structure, which creates a tight seal between the implant and the host tissues, for use in amputation prosthetics.
Appositional enamel growth in molars of South African fossil hominids
Authors: Lacruz Rodrigo S. , Bromage Timothy G. 
Published: June 2006

AbstractEnamel is formed incrementally by the secretory activity of ameloblast cells. Variable stages of secretion result in the formation of structures known as cross striations along enamel prisms, for which experimental data demonstrate a correspondence with daily periods of secretion. Patterns of variation in this daily growth are important to understanding mechanisms of tooth formation and the development of enamel thickness. Transmitted light microscopy (TLM) of histological ground sections and scanning electron microscopy (SEM) of bulk specimens or their surface replicas are the usual methods for investigating cross striations. However, these methods pose some constraints on the study of these features in Plio‐Pleistocene hominid enamel, the specimens of which may only rarely be sectioned for TLM or examined on only their most superficial surfaces for SEM. The recent development of portable confocal scanning optical microscopy (PCSOM) resolves some of the restrictions on fractured enamel surfaces, allowing the visualization of cross striations by direct examination. This technology has been applied here to the study of Australopithecus africanus and Paranthropus robustus hominid molars from the Plio‐Pleistocene of South Africa. We hypothesize that these taxa have increased enamel appositional rates compared with modern humans, because despite having thicker enamelled molars (particularly P. robustus), the enamel crowns of these fossil taxa take an equivalent or reduced amount of time to form. Cross striations were measured in cuspal, lateral and cervical regions of the enamel crowns, and, within each region, the inner, middle and outer zones. Values obtained for A. africanus outer zones of the enamel crown are, in general, lower than those for P. robustus, indicating faster forming enamel in the latter, while both taxa show higher rates of enamel growth than modern humans and the African great apes. This demonstrates a relatively high degree of variability in the mechanisms underlying the development of enamel across taxa.