Biomedical subjects

Iyad Hassan

Publications and source records attributed to Iyad Hassan.

6 recordsLinked to original sources

PubMed2006

Improvement of surgical skills after a three-day practical course for laparoscopic surgery.

OBJECTIVES: Currently, skills labs are becoming increasingly important in the field of medical education. This study aims to objectively assess psychomotor skills acquisition of residents attending a three-day laparoscopic course. MATERIALS AND METHODS: 44 participants (test group) of the sixth practical course for Visceral Surgery of German surgical societies (Deutsche Gesellschaft für Chirurgie; DGCH and Berufsverband Deutscher Chirurgen; BDC) in Warnemuende with various degree of experience in laparoscopic surgery (18 advanced residents performing more than 50 laparoscopic operations and 26 novices performing less than 10 laparoscopic operations) and 6 consultants attending as tutors of the course (gold standard) were recruited as subjects. 20 medical students in their final year (camera holder) were chosen as a second control group (naive). Both control groups had no training during the practical course. The virtual reality simulator LapSim was used to assess laparoscopic skills of participants before and after the course. Time to complete the tasks, error score, and economy of motion parameters (path length and angular path) were analysed. RESULTS: After the practical course the advanced participants of the test group completed the task significantly faster (p = 0.019), with smaller error score (p = 0.023), and more economy of motion [path length (p = 0.014) and angular path (p = 0.049)] than before the course. The novices of the test group and both control groups showed no significant improvement of their performance parameters (p >0.05). CONCLUSION: A three-day practical course for laparoscopic surgery improved laparoscopic skills of residents. However, advanced residents benefit most from the course.

Adult↗

PubMed2006

Supervised surgical trainees perform thyroid surgery for Graves' disease safely.

BACKGROUND: There is little information about the effect of operative experience and supervision of trainees on long-term outcomes after thyroid resection for Graves' disease (GD). The aim of this study was to compare the morbidity rate after thyroid resection performed by trainees vs consultant surgeons. METHODS: Based on a cross-sectional design analysis with a median follow-up of 96 months (range, 12-216 months), long-term outcomes for 111 patients operated on by consultants were compared with those of 42 patients operated on by supervised trainees in an academic teaching hospital between 1987 and 2002. RESULTS: Of the 111 patients operated on by the consultants, there were 25 (21.6%) cases of transient and 12 (10.8%) cases of permanent hypocalcemia and 10 (9.0%) cases of transient and 1 (0.9%) case of permanent recurrent laryngeal nerve (RLN) palsy. Of the 42 patients operated upon by the supervised trainees, there were 8 (21.4%) cases of transient and no permanent hypocalcemia, 3 (7.1%) cases of transient, and 1 (2.3%) case of permanent RLN palsy. Permanent complication rate of the entire group was low, and the grade of the primary surgeon made no difference in the occurrence of complications (P>0.05). CONCLUSION: Supervised trainees can perform thyroid surgery for GD safely if a standardized surgical teaching program is available.

Adolescent↗

PubMed2006

Paneling human thyroid cancer cell lines for candidate proteins for targeted anti-angiogenic therapy.

Tumor angiogenesis is believed to result from an imbalance of pro- and anti-angiogenic factors, some of which are candidates for targeted therapy. Such therapy has raised hopes for patients with undifferentiated thyroid carcinomas, who are facing a grave prognosis with a survival of only months. In this study, in vivo growth of xenografted human thyroid carcinomas unexpectedly responded quite differently to neutralizing anti-vascular endothelial growth factor (VEGF) antibody. In particular, lasting inhibition as well as accelerated growth occurred after treatment. Consequently, a panel of anti-angiogenic factors was addressed in a representative sample of thyroid carcinoma lines. VEGF, fibroblast growth factor (FGF-2), and endostatin were demonstrated by Western blotting and EIA, whereas PDGF-A, PDGF-B, and IL-6 were negative. Quantification of VEGF, FGF-2, and endostatin revealed a wide range of concentrations from 500 to 4,200 pg/ml VEGF, 5 to 60 pg/ml FGF-2, and 50 to 300 pg/ml endostatin, not related to a particular histologic thyroid carcinoma background. Angiostatin (kringles 1-3) was detected in all, but one of the cell lines. Finally, aaATIII was confirmed in FTC133 cells. These data highlight the complex regulation of angiogenesis in thyroid carcinoma cell lines and suggest that the array of angiogenic factors differs markedly between individual cell lines. For the first time, angiostatin, endostatin, and possibly also aaATIII are identified as novel candidate regulators of angiogenesis in thyroid carcinoma cells.

Angiogenesis Inhibitors↗

PubMed2006

Novices in surgery are the target group of a virtual reality training laboratory.

BACKGROUND: This study aims to establish which physicians represent the suitable target group of a virtual training laboratory. METHODS: Novices (48 physicians with fewer than 10 laparoscopic operations) and intermediate trainees (19 physicians who performed 30-50 laparoscopic operations) participated in this study. Each participant performed the basic module 'clip application' at the beginning and after a 1-hour short training course on the LapSim. The course consisted of the tasks coordination, lift and grasp, clip application, cutting with diathermy and fine dissection at increasing difficulty levels. The time taken to complete the tasks, number of errors, and economy of motion parameters (path length and angular path) were analyzed. RESULTS: Following training with the simulator, novices completed the task significantly faster (p = 0.001), demonstrated a greater economy of motion [path length (p = 0.04) and angular path (p = 0.01)]. In contrast, the intermediate trainees showed a reduction of their errors, but without reaching statistical significance. They showed no improvement in economy of motion and completed the task significantly slower (p = 0.03). CONCLUSION: Novices, in comparison to intermediate trainees, tend to benefit most during their first exposure to a laparoscopy simulator.

Adult↗

PubMed2004

Thyrotropin (TSH)-induced production of vascular endothelial growth factor in thyroid cancer cells in vitro: evaluation of TSH signal transduction and of angiogenesis-stimulating growth factors.

Thyroid tumor growth requires angiogenesis, and vascular endothelial growth factor (VEGF) has been shown to be the most important endothelial mitogen. TSH is the major thyrotropic hormone, but its impact to modulate VEGF production has not yet been studied. Several other growth factors have also been shown to affect thyroid cancer cell growth and function in vitro. Therefore, the aim of the current study was to 1) establish the effect of TSH on VEGF as well as 2) evaluate the TSH signal transduction of this effect, and 3) screen other growth factors for the ability to modulate VEGF in thyroid cancer cell lines. HTC, a follicular cancer cell line lacking endogenous TSH receptor (TSHr), its receptor positive variant (HTC TSHr), and a cell line of Huerthle cell origin (XTC) were used. After stimulation with growth factors in vitro [TSH; epidermal growth factor (EGF), IGF, placenta growth factor, TGF-alpha, TGF-beta1, fibroblast growth factor, platelet-derived growth factor, and hepatocyte growth factor] cells were analyzed for VEGF gene expression by Northern blotting and for VEGF protein by enzyme immunoassay. TSHr signal transduction was evaluated by analyzing the effect of stimulators (cholera toxin, 8-bromo-cAMP, forskolin, and 12-O-tetradecanoyl-phorbol-13-acetate) and inhibitors (2',5'-dideoxyadenosine and staurosporine) on VEGF protein levels under basal and TSH-stimulated conditions. TSH increased VEGF mRNA and protein in a dose-dependent manner in HTC TSHr and XTC cells by up to 40%. The effects of TSH were mediated by protein kinase C (PKC), rather than protein kinase A (PKA), stimulation, because inhibition of PKC by staurosporine resulted in a decrease in VEGF production of up to 65%, whereas inhibition of the PKA signal transduction pathway (2',5'-dideoxyadenosine) resulted in only a minor decrease. TSH was not the most powerful stimulator of VEGF production. TGF-beta1 and EGF were 1.5- to 2-fold more potent. Placenta growth factor and TGF-alpha did not induce VEGF production in TSHr-positive HTC cells, whereas they did induce VEGF production in TSHr-negative HTC cells. In thyroid cancer cell lines, TSH induces VEGF production involving the PKC, rather than the PKA, pathway. However, EGF and TGF-beta increase the capacity of thyroid cancer cells to provide VEGF more effectively than TSH. In the absence of a functioning TSHr, additional growth factors, such as TGF-alpha, increase capacity for VEGF stimulation.

Cell Line, Tumor↗

PubMed2002

VEGF-mediated angiogenesis of human pheochromocytomas is associated to malignancy and inhibited by anti-VEGF antibodies in experimental tumors.

BACKGROUND: Pheochromocytomas are well-vascularized tumors of the adrenal medulla. In human pheochromocytomas, angiogenesis has been associated with tumor progression. The mechanisms, however, are unknown. METHODS: Surgical specimens of benign, invasive, and metastatic human pheochromocytomas (n = 10/5/5) were immunostained for vascular endothelial growth factor (VEGF) and CD34, to determine VEGF expression and microvessel density (vascular surface density, [VSD]). In PC12-pheochromocytoma cells, VEGF messenger RNA and protein were analyzed by Northern blotting and enzyme immunoassay; biologic activity by human umbilical vein endothelial cell-proliferation assay. Inhibition of angiogenesis of PC12 xenografts by 2 neutralizing anti-VEGF antibodies (C20-pAB, M461-mAB) was evaluated by VEGF expression, VSD, and mitotic activity. RESULTS: VEGF expression and VSD were significantly higher in metastatic pheochromocytomas (VEGF 37.1 +/- 10.9% vs 20.7 +/- 9%, VSD 26.2 +/- 8 vs 13.5 +/- 3.3 1/mm). VEGF messenger RNA and protein were confirmed in PC12 cells and stimulated by nerve growth factor. Conditioned PC12 medium increased human umbilical vein endothelial cell proliferation more than 2-fold. Xentrotransplanted PC12 cells had marked VEGF expression and angiogenesis, which was inhibited by anti-VEGF antibodies (VEGF-expression by 29 and 38%, VSD by 43 and 46%, P <.05). CONCLUSION: Higher VEGF expression and microvessel density in malignant pheochromocytomas suggest VEGF-mediated angiogenesis to be related to tumor progression. Angiogenesis of PC12 xenografts is mediated by VEGF. Neutralizing anti-VEGF antibodies inhibit angiogenesis in experimental pheochromocytomas and may have potential for treating nonresectable pheochromocytomas.

Adrenal Gland Neoplasms↗