124,760 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
SIXTY-TWO CONSECUTIVE LAPAROSCOPIC MINOR LIVER RESECTIONS OF THE POSTERO-SUPERIOR SEGMENTS. A SHORT-TERM OUTCOME ANALYSIS.
No full textDispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Early, Strangulated Recurrence of Incisional Hernia After Laparoscopic Repair: An Old Complication for a New Technique.
No full textThe introduction of laparoscopy in incisional hernia repair is giving rise to a new class of complications, specific of new techniques and materials. A case of early failure of incisional hernia laparoscopic repair complicated by the strangulation of a jejunal loop four months after surgery is reported. The use of inappropriate material (tacks) to fix the prosthesis to the abdominal wall, a sudden increase of intra-abdominal pressure caused by an episode of haematemesis four hours postoperatively (associated to its consequent endoscopic treatment), and the formation of rectus abdominis muscle hematoma are reported as the main factors determining the slippage of the mesh from the correct position and, ultimately, the early failure of the ventral hernia repair. Furthermore, the aetiology of early failure of laparoscopic incisional hernia repair, reported in literature, is reviewed
Dual role of VEGF in pretreated experimental ePTFE arterial grafts
No full textBackground. Lack of endothelialization and abnormal smooth muscle cell (SMC) growth adversely affect the outcome of vascular synthetic grafts. The aims of our study were to investigate how a coating of extracellular matrix (ECM) and vascular endothelial growth factor (VEGF) might affect the endothelialization rate, smooth muscle cells (SMC) proliferation, and myointimal hyperplasia in experimental arterial ePTFE grafts. Methods. In each of 30 male Lewis rats, a 1-cm-long ePTFE graft was inserted at the level of the abdominal aorta. Animals were randomized in five groups (six animals each): groups A and A1 received ePTFE grafts coated with a synthetic extracellular matrix (growth factor-reduced matrigel) containing VEGF; groups B and B1 received ePTFE grafts coated with synthetic ECM; and group C received ePTFE grafts alone. The grafts were explanted at 30 days from surgery for immunohistochemical analysis. Results. Both endothelialization rate and myointimal hyperplasia were augmented in group A versus groups B and C, and these findings were statistically significant. SMC density resulted significantly higher in group A versus groups B and C, and this was associated with an altered expression of bFGF and TGF beta. Conclusions. Pretreating ePTFE grafts with synthetic ECM and VEGF results in better endothelialization, but also in undesired higher SMC density and myointimal hyperplasia. (c) 2005 Elsevier Inc. All rights reserved
COLORS, LUMINOSITIES, AND MASSES OF DISK GALAXIES .2. ENVIRONMENTAL DEPENDENCIES
No full textThe B-band and near-infrared (H) luminosity functions of spiral galaxies are derived for the Coma and A1367 clusters and for a reference population of ''field'' galaxies in the Coma supercluster. They are consistent at the bright end, but they differ significantly at the faint end, indicating an overdensity of spirals with blue color (B-H -21.5) in clusters with respect to the field. These objects have disturbed morphology and peculiar velocities significantly larger than the rest of the cluster sample. We discuss these results in the framework of a possible environmental dependence of galaxy evolution, and we conclude that enhanced current star formation in cluster spiral galaxies might occur due to molecular gas collapse stimulated by the ram-pressure mechanism
Increased production of cytokines and growth factors by aortic allografts: A possible explanation for myointimal hyperplasia formation
No full textAccelerated myointimal hyperplasia is a major complication of arterial allografts. The aim of our study was to analyze the role of growth factors in the genesis of myointimal hyperplasia in arterial allografts. Two groups of experiments were performed: Isografts and Allografts. The Isograft group consisted of 18 inbred Lewis rats in which a 1-cm long segment of aorta was inserted as abdominal aortic interposition graft. The aortic segments were obtained from syngeneic Lewis rats. The Allograft group consisted of 18 inbred Lewis rats, in which a 1-cm long segment of aorta was interposed at the level of the abdominal aorta. The aortic segments were obtained from allogeneic Brown-Norway rats. No immunosuppression was used. The animals were sacrificed 4 weeks after surgery and the aortic grafts were analyzed by light, electron microscopy (n = 3 for each group) and immunohistochemistry (n = 3 for each group). In addition, aortic segments (n = 12 for each group) were put in an organ culture to assess production of growth factors. All allografts showed evidence of severe myointimal hyperplasia, which was minimal in isografts. PDGF, bFGF and TGF-β1 production, generally considered to be the cause of myointimal hyperplasia, was not increased in allografts, whereas IL-1, TNF-α and GM-CSF production was increased in allografts and probably lymphocytes were the source of these cytokines (p < 0.001). We conclude that myointimal hyperplasia in aortic allografts is associated with an increase of IL-1, TNF-α and GM-CSF produced by lymphocytes
LAPAROSCOPIC MINOR PANCREATIC RESECTIONS (ENUCLEATIONS/ATYPICAL RESECTIONS). A LONG-TERM APPRAISAL OF A SUPPOSED MINI-INVASIVE APPROACH.
No full textIntroduction
Few retrospective, small-sized, often multicentric studies show encouraging results of laparoscopic minor pancreatic surgery, but do not allow for an evaluation of feasibility and effectiveness.
Aim
The purpose of the paper is to evaluate the results of laparoscopic pancreatic minor resections (LMPR), including atypical resections and enucleations.
Material and Method
Outcome of all consecutive patients undergoing LMPR in a Tertiary Care University Hospital specializig in the laparoscopic approach to solid organs (I.M.M., Paris – France), was retrospectively evaluated by the analysis of operating time, blood loss, conversion, morbidity, stay and late outcome.
Results
Thirthy-three patients underwent LMPR (29 enucleations and 4 atypical resections) for various affections. Conversion rate was 21%, mean operating time 189 minutes, and mean blood loss 133 ml. Morbidity was 60%; 10 patients (30%) presented a pancreatic fistula. Pancreatic fistula was independent of type of resection, technique of pancreas section, management of enucleated surface and somatostatine administration. Median stay for enucleations was 18 days. Mean follow up was 61 months.
Conclusions
Laparoscopic pancreatic enucleations are feasible and safe, with no mortality, no lengthening of operating time and high success rate; conversely, it does not imply a reduction in complications and hospital stay at the present state of the art
CHOLECYSTO-COLONIC FISTULA: FACTS AND MYTHS. A review of the 231 published cases.
No full textBACKGROUND: Cholecystocolonic fistula (CCF) is the second most common cholecystoenteric fistula and is often discovered intraoperatively, resulting in a challenging situation for the surgeon, who is forced to switch to a complex procedure, often in old, unfit patients. Management of this uncommon but possible finding is still ill defined.
METHODS: An extensive review of 160 articles published from 1950 to 2006 concerning 231 cases of CCF was performed.
RESULTS: CCF is mostly an affliction of women in their sixth to seventh decades and is rarely diagnosed preoperatively. Chronic diarrhea is the key symptom in nonemergency patients, but, in one-fourth of cases, CCF presents with an acute onset, mostly biliary ileus. In one-fourth of patients, a second hepatobiliary abnormality is present, including gallbladder cancer in 2% of cases. In uncomplicated cases, diverting colostomy is not performed anymore, and laparoscopy treatment has been described in specialized centers. Symptomatic treatment of concomitant biliary ileus (without treating CCF) is a feasible option. Resolution of colonic biliary ileus by interventional endoscopy is reported.
CONCLUSION: CCF should be considered in differential diagnosis of diarrhea, especially in old, female patients. A possible second hepatobiliary abnormality should be always investigated. Extemporaneous frozen section should be performed if gallbladder cancer is suspected. Depending on clinical presentation, different treatments for CCF are indicated, ranging from minimally invasive procedures to extensive resection
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