Laparoscopic partial splenectomy.
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Carcinoma, Papillary↗
Biomedical subjects
Thomas Scholz
Publications and source records attributed to Thomas Scholz.
Laparoscopic pouch resizing and redo of gastro-jejunal anastomosis for pouch dilatation following gastric bypass.
BACKGROUND: With a dramatically increasing number of bariatric operations performed world-wide in the recent years, more late complications have been noticed. Proximal gastric pouch dilatation is a known late complication after laparoscopic or open restrictive surgery for morbid obesity. In the present paper, we report our experience with laparoscopic re-operation of enlarged gastric pouches after laparoscopic gastric bypass, with emphasis on technique and outcome. METHODS: Data were retrieved from a prospective database of 334 patients who underwent a laparoscopic gastric bypass operation at the University Hospital of Zurich from July 2000 to December 2004. Five laparoscopic revisions for pouch dilatation after primary bypass were performed. RESULTS: 3 female and 2 male patients with median age 40 years (range 32-55) underwent a laparoscopic pouch resizing. At the time of the re-operation, the median BMI was 32.0 kg/m(2) (range 28.4-48.4). All procedures were performed laparoscopically with no conversion to open surgery. The median operating-time was 110 minutes (95-120). The median hospital stay was 6 days (range 5-14). The median BMI in the follow-up of 12 months (9-14) was 28.0 kg/m(2) (25.5-45.8). Diabetes mellitus improved in 4 cases during follow-up. CONCLUSION: Laparoscopic pouch resizing with redo of the gastro-jejunal anastomosis was feasible, safe and effective in this small series. It led to further weight loss and improved symptoms of poor pouch emptying.
Adult↗
Platelet-derived microvesicles transfer tissue factor to monocytes but not to neutrophils.
Activated platelets are known to adhere to both blood monocytes and neutrophils, and this adhesion is mainly mediated by the surface exposure of the platelet granule protein CD62P. Platelets as well as platelet-derived microvesicles (PMV) have also been shown to contain and to transfer tissue factor (TF), the most important initiator of intravascular thrombin and fibrin formation, to monocytes. However, the role of neutrophils for gathering platelet-derived TF is controversial. Here we studied the interaction of PMV with monocytes and neutrophils using a whole blood system. Platelet-rich plasma (PRP) obtained from citrated human blood was incubated with collagen (5 microg/ml, 15 min) and the platelets were removed by centrifugation (5 min at 5000 x g). After incubating the PMV-containing plasma for further 30 min with a sediment of red and white bloods cells that had been obtained after PRP preparation, monocytes and neutrophils were analysed by flow cytometry for the surface exposure of the platelet-specific antigen CD42a and TF. Compared to a control with non-activated PRP, there was a significant increase in the number of both CD42a-positive monocytes and neutrophils. In contrast, there was no change in the number of TF-positive neutrophils, but a more than 2-fold increase in the number of TF-positive monocytes. The changes in CD42a on monocytes and neutrophils as well as the changes in TF on monocytes could be significantly reduced by an anti-CD62P antibody or by removal of PMV from the plasma samples. The data indicate that the transfer of TF to monocytes is not simply an CD62P-mediated adhesion of platelets or PMV to monocytes, but may involve other not yet identified mechanisms.
Biological Transport↗
Primary nerve grafting: A study of revascularization.
It was the purpose of this study to evaluate the revascularization of primary nerve repair and grafts using orthogonal polarization spectral (OPS) (Cytometrix, Inc.) imaging, a novel method for real-time evaluation of microcirculatory blood flow. Twenty male Sprague Dawley rats (250 g) were anesthetized with vaporized halothane and surgically prepared for common peroneal nerve resection. Group I animals (n = 10) underwent primary neurorraphy following transection, utilizing a microsurgical technique with 10-0 nylon suture. Group II (n = 10) animals had a 7-mm segment of nerve excised, reversed, and subsequently replaced as a nerve graft under similar techniques. All animals were evaluated using the OPS imaging system on three portions (proximal, transection site/graft, and distal) of the nerve following repair or grafting. Reevaluation of 5 animals randomly selected from each group using the OPS imaging system was again performed on days 14 and 28 following microsurgical repair/grafting. Values were determined by percent change in vascularity of the common peroneal nerve at 0 hr following surgery. Real-time evaluation of blood flow was utilized as an additional objective criterion. Percent vascularity in group I and II animals increased from baseline in all segments at day 14. By day 28, vascularity in nerves of group I rats decreased in all segments to values below baseline, with the exception of the transection site, which remained at a higher value than obtained directly after surgical repair. In group II animals, vascularity remained above baseline in all segments except the distal segment, which returned to vascularity levels similar to those at 0 hr. Further, occlusion of the vessels demonstrated in the graft and distal segments following initial transection appeared to be corrected. This study suggests that revascularization may occur via bidirectional inosculation with favored proximal vascular growth advancement. The use of real-time imaging offers a unique evaluation of tissues through emerging technologies.
Animals↗
Laser flap delay: comparison of Erbium:YAG and CO2 lasers.
The delay phenomenon has long been recognized as a powerful tool in reconstructive surgery. This phenomenon involves creating alterations in skin flap blood supply or microcirculation to increase the size of the surviving flap. In the past many reconstructive surgeons depended on surgical delay as an integral part of their surgical planning. Today surgical delay remains a reliable method for maximizing flap survival. Although surgical delay remains the gold standard many have searched for methods to create the same effect with less morbidity and reduced cost. The purpose of this study was to determine whether near-scarless delay can be performed with either the Erbium:YAG or CO2 laser using a standard McFarlane skin flap model. Four groups were identified. Surgical delay, Erbium laser delay, and CO2 laser delay groups were each compared with a nondelayed control. Each group consisted of ten Sprague-Dawley rats. On Day 0 all delay procedures were performed on the lateral periphery of the outlined dorsal skin flaps. Interruption of this lateral blood supply was accomplished by two parallel 10-cm incisions in the surgical delay group. Likewise blood supply and microcirculatory alterations were accomplished in the laser delay groups by two parallel 10-cm laser treatments. On Day 7 a 10 x 4-cm cranially based dorsal skin flap was elevated. On Day 14 flap survival was analyzed by calculating percentage flap survival. The Erbium:YAG laser delay of the McFarlane flaps resulted in an average of 32 per cent less flap loss compared with controls (P = 0.0001). The CO2 laser resulted in an average of 36 per cent less flap loss compared with controls (P = 0.0002), whereas the surgical delay group had a 23 per cent smaller flap loss (P = 0.009). There was no significant difference between any of the delay groups. These results indicated that CO2 and Erbium:YAG lasers are as effective as surgery for delay of skin flaps in the rat model. They may provide an effective and inexpensive method for near-scarless skin flap delay in humans.
Animals↗
The GPIIb/IIIa antagonist eptifibatide markedly potentiates platelet-leukocyte interaction and tissue factor expression following platelet activation in whole blood in vitro.
Tissue factor (TF) is the most important initiator of intravascular coagulation. Activated platelets are able to adhere to leukocytes and this heterotypic cell-cell interaction results in a CD62P-dependent TF expression on monocytes. GPIIb/IIIa antagonists are inhibitors of the common pathway of platelet aggregation and they are widely used in patients with acute coronary syndromes undergoing coronary interventions. As GPIIb/IIIa antagonists do not prevent platelet activation we investigated the effect a GPIIb/IIIa antagonist, eptifibatide, on the formation of platelet-leukocyte conjugates and leukocyte TF expression. Flow cytometry was used to detect conjugates and TF. When platelets in citrated human blood were stimulated for 30 min with collagen there was a increase in the number of both neutrophils and monocytes with the platelet-specific antigen CD42a, indicating the formation of platelet-neutrophil (P/N) and platelet-monocyte (P/M) conjugates. P/M formation was associated with about a 2.5-fold increase in TF expression on monocytes, whereas P/N formation changed TF expression neutrophils only by about 10%. Eptifibatide enhanced dose-dependently (0.0625-1.5 microg/ml) both collagen-induced P/M formation and monocyte TF expression. Maximum enhancement by about 60 and 120%, respectively, was observed at 0.5 microg/ml eptifibatide. In contrast, eptifibatide had only a minor effect on P/N formation and no effect on neutrophil TF expression. The augmented P/M formation and monocyte TF expression in the presence of a GPIIb/IIIa antagonist may be relevant to the poor antithrombotic efficiency of oral GPIIb/IIIa antagonists as shown in recent large clinical trials.
Blood Platelets↗
Transfer of tissue factor from platelets to monocytes: role of platelet-derived microvesicles and CD62P.
Tissue factor (TF) is the most important initiator of intravascular coagulation. Platelets contribute to TF exposure on monocytes, but the mechanism is not completely understood. Here we examined the possibility that platelets may release TF that can be transferred to monocytes by platelet-derived microvesicles. When human citrated platelet-rich plasma was incubated with collagen there was an increase in the plasma levels of TF and CD62P. Incubation of plasma obtained from collagen-stimulated PRP with a sediment of red and white blood cells resulted in an increase in the number of monocytes that express TF, CD62P and the platelet-specific antigen CD42a on their surface. This transfer of platelet-derived antigens to monocytes was reduced when CD62P was blocked by a specific antibody or when platelet-derived microvesicles were removed from the plasma either by high speed centrifugation (17,500 x g for 30 min) or by filtration (pore size 0.2 microm). The data indicate that platelet-derived microvesicles that are released from collagen-stimulated platelets may carry TF, CD62P and CD42a and may transfer these antigens to the surface of monocytes. The interaction of platelet-derived microvesicles with monocytes and the transfer of TF to monocytes strongly depend on CD62P.
Blood Platelets↗