Gender discrimination in endoscopic groin hernia repair. Minimal invasive groin hernia repair is offered less often to female patients compared to male patients.

BACKGROUND: Groin hernia repair constitutes a very common procedure in general surgery. Minimal invasive closure of groin hernia has evolved to become the standard means of closure. However, there seems to be a gender-associated discrimination with regard to endoscopic groin hernia repair. We investigated the rate of endoscopic closure in female patients undergoing groin hernia closure. MATERIALS AND METHODS: A retrospective analysis of the data of patients undergoing elective groin hernia repair within a four-year period from 2013 to 2016 was performed. The rate of endoscopic hernia repair was calculated for both genders. RESULTS: Eight hundred and forty-six patients including 94 females and 752 males were included for analysis. The female group was significantly older compared to the male group (68.0 vs. 61.0 yrs, P=0.02). The rate of endoscopic groin hernia repair was significantly lower in the female group compared to in the male cohort (30% vs. 60%, P=0.001). The overall duration of surgery was 74.0min in the female cohort and 93.0min in the male group, P=0.001. However, there was no statistically significant difference amongst both groups with regard to the duration of surgery for endoscopic repair: 78.0min in the female group and 89.0min in the male group, P=0.67. CONCLUSION: Findings from this retrospective collective suggests that, there might be some degree of sex discrimination with regard to endoscopic groin hernia repair in favor of the male population.

Initial experience with taTME in patients undergoing laparoscopic restorative proctocolectomy for familial adenomatous polyposis.

BACKGROUND: Transanal total mesorectal excision (taTME) is a minimally invasive technique which was developed to overcome the difficulties associated with the "top-down" pelvic dissection by enabling a "bottom-up" dissection in patients with mid- and low rectal cancer. While this technique was primarily designed to manage tumors in the mid- and lower rectum, its spectrum of indications has been broadened to include benign colorectal pathologies. The aim of the present study was to assess our initial experience with taTME in patients undergoing restorative proctocolectomy for familial adenomatous polyposis (FAP). METHODS: All consecutive patients (undergoing prophylactic restorative proctocolectomy with IPAA for FAP using taTME between April and October 2016 at our institution) were included in the study. RESULTS: There were 8 patients (6 females and 2 males). The median age was 19.5 years (range 16-31 years). In all cases, surgery was successfully completed using with taTME. No perioperative complications were recorded. A median of 5 bowel movements (range 4-6 bowel movements) with intermittent anti-diarrheal medication was recorded in all cases. CONCLUSIONS: Our initial experience with 8 consecutive cases suggests taTME is safe and effective in patients undergoing prophylactic restorative proctocolectomy with IPAA for FAP.

Primary peritoneal adenocarcinoma as content of an incarcerated umbilical hernia: A case-report and review of the literature.

INTRODUCTION: Umbilical hernia is a common finding in many cases, posing potentially life-threatening complications, such as incarceration or strangulation. The presence of malignancy in hernia sacs is, however, rather rare. PRESENTATION OF CASE: Here we report on a case of primary peritoneal adenocarcinoma found through histological examination of omental tissue, resected due to an incarcerated umbilical hernia of an 84-years-old woman. There was no macroscopic sign of malignancy during operation; only after routine examination of histological sections the diagnosis was found. DISCUSSION: To our knowledge this is the first report of primary peritoneal cancer as content of an umbilical hernia. This is a rare neoplasm and histologically identical to epithelial ovarian carcinoma. For this reason, the diagnosis is usually based on the histological finding and exclusion of a primary ovarian tumor. Primary peritoneal cancer has a poor outcome in general. Early diagnosis is, therefore, essential for effective treatment. CONCLUSION: Histological analysis of resected hernia sac or content should be performed routinely to discover malignant diseases in the background of a hernia.

[Young Women - Problematic Patients in Vascular Surgery]. / Junge Frauen - Problempatientinnen in der Gefäßchirurgie.

The treatment of peripheral arterial disease (PAD) in young women between 40 and 60 years of age represents a difficult challenge for the vascular surgeon. Excessive smoking, an early menopause and the unfavourable anatomic proportions of thinner arterial vessels or vein grafts during peripheral bypass-surgery lead to a higher rate of complications or re-occlusion following invasive therapy in comparison to male patients. A special anatomic manifestation appearing nearly only in women around the 6th decade is the so-called aortoiliac hypoplastic syndrome with a high rate of re-occlusion after balloon-dilatation or local thrombendarteriectomy and bypass grafting, respectively. Variabilities in coagulation and the undertreatment of classical risk factors of PAD by medical drugs lead to poorer results in the treatment of PAD in young women. Therefore a conservative therapy - whenever feasible - should be the first choice for treating PAD in young women.

[Wrong site surgery : Incidence, risk factors and prevention]. / Verwechselungseingriffe in der Chirurgie : Inzidenz, Risikofaktoren und Prävention.

BACKGROUND: Wrong site surgery defines a category of rare but totally preventable complications in surgery and other invasive disciplines. Such complications could be associated with severe morbidity or even death. As such complications are entirely preventable, wrong site surgery has been declared by the World Health Organization to be a "never event". MATERIAL AND METHODS: A selective search of the PubMed database using the MeSH terms "wrong site surgery", "wrong site procedure", "wrong side surgery" and "wrong side procedure" was performed. RESULTS: The incidence of wrong site surgery has been estimated at 1 out of 112,994 procedures; however, the number of unreported cases is estimated to be higher. Although wrong site surgery occurs in all surgical specialities, the majority of cases have been recorded in orthopedic surgery. Breakdown in communication has been identified as the primary cause of wrong site surgery. Risk factors for wrong site surgery include time pressure, emergency procedures, multiple procedures on the same patient by different surgeons and obesity. Check lists have the potential to reduce or prevent the occurrence of wrong site surgery. CONCLUSION: The awareness that to err is human and the individual willingness to recognize and prevent errors are the prerequisites for reducing and preventing wrong site surgery.

[Groin abscesses and vascular catastrophes in intravenous drug users--strategy and results]. / Leistenabszesse und ,,vaskuläre Katastrophen" bei intravenösem Drogenabusus--Strategie und Ergebnisse.

BACKGROUND: Drug addiction is a global medical and public health-care problem. Infections of the groin and fossa cubitalis are a common clinical problem in these patients. Severe vascular complications are rare but if they occur, therapy is difficult and requires emergency management and surgery because of bleeding problems. METHODS: In a retrospective case series, we report on patients treated within an emergency setting in our hospital because of groin abscesses with vascular involvement between 2003 and 2006. The therapeutic concepts and results are reported and discussed in the context of a review of the international literature. RESULTS: We report on 4 patients with a long-standing history of i. v. drug abuse (average age 33, range 29-36 years). All were hepatitis C Ag positive and HIV negative. The general health and nutritional status were not compromised, all patients had one or more DVT in their medical history. In two cases, emergency surgery with revascularisation was necessary (after 2 days in one case and 4 weeks in the other) because of septic bleeding subsequent to abscess incision. Two patients underwent primary revascularisation because of pseudoaneurysms. The grafts were a saphenous vein patch and a superficial femoral artery patch in one and deep vein segments in two cases. In two cases, a sartorius muscle flap and VAC therapy were used to cover the defect. All patients survived, minor amputation became necessary in one case. CONCLUSION: Abscess excision and debridement have to be as complete as possible and primary revascularisation is the procedure of choice in cases of severe groin infection. In the case of large vessel involvement, abscess incision alone without revision of the vascular structures is dangerous because of subsequent complications like secondary ruptures. For this reason, these patients require intensive care and close monitoring. Successful treatment exclusively based on ligation is described in literature with regard to isolated lesions of the superficial or deep femoral artery. Because of the very common involvement of the femoral bifurcation, revascularisation is, however, necessary in most cases and should be performed with autologous grafts if possible. If complete covering of the defect is not possible, a sartorius muscle flap is a good choice. Primary wound closure can be problematic because of recurrences, therefore vacuum-assisted wound closure is a valuable addition to the overall therapeutic approach in these cases.

Comparison of a beta-blocker and an If current inhibitor in rabbits with myocardial infarction.

AIM: We compared protective effects of a ss-adrenoceptor blocker (metoprolol; Met) and a If current (Ivabradine; Iva) in a rabbit model of myocardial infarction. METHODS: Experiments were performed on 44 adult New-Zealand-White (NZW) rabbits. The effects of either metoprolol or ivabradine were assessed 15 min after experimental occlusion of a coronary artery (CAO), 28 days after CAO (drug gavage), and in vitro hearts (Langendorff apparatus). The results were compared with sham and placebo hearts. RESULTS: Metoprolol (0.25 mg/kg) slightly reduced heart rate and left ventricular systolic function. Ivabradine (0.25 mg/kg) reduced heart rate significantly (P<0.05) (18% vs control). Both drugs provided advantages over placebo: mortality was significantly (P<0.01)smaller (6/13 Pla animals died, 2/10 Met animals, and 3/11 Iva animals), left ventricular function was better preserved after 28 days (external power; Pla; Met; Iva=56%; 76%; 74%), and dilatation (BNP) was reduced (P<0.05). In the Pla group, the ST segment was significantly (P<0.05) elevated by 0.35 mV after CAO and exhibited in 50% of the animals Q waves after 28 days, while after ivabradine or metoprolol, ST displacement and Q waves had disappeared. The uneconomic myosin isoenzyme V3 predominated in Met hearts and Iva hearts (V3/V1: 63/37% and 62/38%), while it was further increased in Pla hearts (78/21%). External efficiency was lowest in Pla hearts (1.00+/-0.50 a.u.; P<0.05) and was significantly higher both in Met hearts (4.0+/-1.8 a.u.) and in Iva hearts (3.3+/-1.6 a.u.). CONCLUSIONS: Met and Iva seem suited for the treatment of chronic myocardial infarction.

Comparison of biomaterials: three meshes and TAPP for inguinal hernia.

BACKGROUND: In laparoscopic hernia repair the use of biocompatible materials is necessary. A prospective, double-blind study was projected to compare three different meshes. METHODS: Ninety male patients with primary inguinal hernia undergoing transabdominal preperitoneal (TAPP) implant procedures were included. Three different types of mesh were tested: a monofile, heavy-weight, rigid mesh (group A), a smooth, heavy-weight variant of polypropylene (group B), and a polyglactin/polypropylene compound mesh (group C). Complications, pain development, inability to work, physical conditions, testicular volume, and blood circulation were documented. RESULTS: Convalescence in group A was slower than in groups B and C: Postoperative values of visual scales for pain development were higher, inability to work was 7.3 days longer, urologic effects were more severe, activities of everyday life were more reduced, and data of the German SF-36 Health Survey Test showed a significant reduction of physical condition (p < 0.05). CONCLUSION: The compound mesh did not create more comfort for the patients than the smooth variant of the heavy-weight polypropylene mesh.

Comparison of biomaterials in the early postoperative period.

BACKGROUND: Laparoscopic hernia repair necessitates the use of biocompatible materials. A prospective, double-blind study was conducted to compare two different polypropylene meshes. METHODS: The study included 40 men with primary inguinal hernia undergoing transabdominal preperitoneal polypropylene mesh repair. In 20 of these men, a monofile, heavy-weight, rigid mesh was implanted (group A), and in the remaining 20 men, a smooth, heavy-weight variant of polypropylene mesh was implanted (group B). Complications, pain development, inability to work, physical conditions, testicular volume, and blood circulation were documented. RESULTS: Reconvalescence in group A was slower than in group B. In group A, the postoperative values of the visual scales for pain development were higher; inability to work was 7.3 days longer; urologic disorders were worse; activities of everyday life were more reduced; and SF-36 data showed a significant reduction of physical problems ( p < 0.05). CONCLUSIONS: The polypropylene mesh variant seems to be more compatible with the human organism than conventional mesh. Not only the material, but also the structure seems to influence the comfort of the mesh.

[Urological symptoms after laparoscopic hernia repair. Reduction with a variant of polypropylene mesh]. / Urologische Symptome nach laparoskopischer Leistenhernienversorgung. Reduktion durch Polypropylennetzvariante.

In the context of a prospective, randomized, controlled double-blind study concerning a reduction of postoperative, urogenital affections after laparoscopic hernia repair using a polypropylene mesh, laparoscopic polypropylene implantation was performed in 40 male patients. Twenty patients received a heavyweight, rigid polypropylene mesh (group A) and the remainder a heavyweight, but softer polypropylene mesh (group B). Questionnaires were used to assess the severity of pain, impairment of sexual life, appearance of urogenital affections, and general condition. On the 3rd postoperative day, testicle blood circulation and testicle volumes were documented by ultrasound, and a congestion of the plexus pampiniformis was excluded by ultrasound with 5 MHz. Starting in the 1st postoperative week, a prevalence of affections such as testicular sensitivity to touch, pain upon ejaculation, and a pulling sensation during urination became apparent in group A. In the 12th postoperative week, 20% in group A still described testicular sensitivity to touch and 10% pain upon ejaculation and a pulling sensation during urination but only 5% in group B. It is essential to reduce urogenital affections after laparoscopic hernia repair by strict indications and appropriately adapted polypropylene meshes.

Perioperative levels of atrial natriuretic peptide and troponin-T in patients with uncomplicated coronary artery surgery.

HYPOTHESIS: increased ANP levels after uncomplicated coronary artery surgery (CAS) indicate functional reduction. EXPERIMENTAL DESIGN: prospective, randomized. Preoperative upto the 12 week postoperative. SETTING: Thoracic and Cardiovascular Surgery, University of Düsseldorf. PATIENTS: 15 patients (mean age: 58+/-6.1 years; 13 months, 2 weeks; no myocardial infarction, no congestive heart failure) with 3 vessel disease. INTERVENTIONS: levels of atrial natriuretic peptide (ANP) (pg/ml; radioimmunoassay), Troponin T (TnT) (ng/ml; ELISA test), haemodynamic parameters, ECG monitoring, m-mode echocardiography (Echo). MEASURES: increase of ANP, TnT levels during extracorporeal circulation (ECC), decrease after operation. RESULTS: Maximal increase of ANP from preoperative 90+/-10 (M+/-SEM) pg/ml (p<0.05) up to intraoperative 380+/-38 pg/ml. Ten days postoperative ANP (26+/-33 pg/ml) still threefold increased compared to preoperative level. Increasement of TnT from preoperative 0.02+/-0.01 ng/ml upto intraoperative 3.44+/-0.47 ng/ml. Ten days postoperative TnT concentration normal (0.13+/-0.11 ng/ml). Correlation of ANP and TnT five min after bypass up to 6 hrs postoperative (p<0.05, r =3.4). Increase of left atrial diameter preoperative 42.2+/-1.1 mm up to 46.8+/-1.2 mm (p<0.05) 10 days postoperative. LVEDD, EF changed from preoperative 51.1+/-0.9 mm, 73+/-2% to 54.5+/-1.2 mm, 65+/-4% 10 days postoperative. CONCLUSIONS: Threefold increase of ANP 10 days postoperative and return of TnT levels to normal under consideration of datas of echo show, that ANP is suitable to indicate the meanterm, functional, myocardial reduction. Increased ANP levels, atrial dilatation and dysfunction are important signs of cardial functional reduction after CAS.

Sympathetic nervous system activity during laparoscopic and needlescopic cholecystectomy.

BACKGROUND: It is difficult to quantify the impact of surgical trauma on patients with conventional measurement techniques. We report our preliminary experience with the determination of sympathetic nervous system activity during laparoscopic and needlescopic cholecystectomy. METHODS: The electroconductivity of representative dermatomes (24 measuring points) was recorded prior, during, and after performing laparoscopic and needlescopic cholecystectomy on 40 consecutive patients according to the method of Nakatani (Ryodoraku). Fifty-five healthy adults served as a control group. RESULTS: Median age in the two groups was 52.4 and 54.1 years, respectively. Prior to the operation and on the 1st postoperative day, sympathetic nervous activity was equal in both groups. In the needlescopic patients, sympathetic activity was lesser at 30 min after the start of the laparoscopic procedure (p <0.05). CONCLUSIONS: The measurement of electroconductivity is a useful noninvasive technique for the evaluation of sympathetic nervous activity. As far as activation of sympathetic nervous system is concerned, the needlescopic technique was found to be superior.

[Determination of the axis after totalendoprosthesis of the knee: functional X-ray photography as golden standard]. / Achsvermessung bei Knie-TEP: Ganzbeinstandaufnahme als Golden Standard.

AIM: To examine the question of which X-ray photography technique should be given preference after implantation of total endoprosthesis of the knee. METHOD: 20 patients (age 74.1; 12 men, 8 women) with total endoprosthesis of the knee (Type Sigma, PFC, Johnson and Johnson) because of primary athrosis. Postoperatively X-ray photographs of the whole leg in standing and 40 x 20 a. p. in a flat position were taken. The angles of the axis were determined and the information analysed. RESULTS: By means of X-ray photography of the whole leg we obtained the following angles: caput-collum-diaphyse 125 +/- 4.3 degrees, femur/basis of the knee 83.2 +/- 2.6 degrees, mechanical femur axis/basis of the knee 89.3 +/- 1.8 degrees, tibia/basis of the talus 89.2 +/- 2.2 degrees. With the 40 x 20 a. p. X-ray photographs we determined the following angles: femur/basis of the knee 82.3 +/- 3.1 degrees, basis of knee/tibia 92.2 +/- 3,6 degrees. Correlating the angles of femur/basis of the knee and basis of the knee/tibia were relations of 0.42 (p < 0.05) and 0.27 (p < 0.05). CONCLUSION: For gaining information about the axis of the leg under functional conditions, one should give preference to X-ray photography of the whole leg.

[Diagnosis of appendicitis with particular consideration of the acupuncture point Lanwei--a prospective study]. / Die Diagnostik der Appendizitis unter besonderer Berücksichtigung des Akupunkturpunktes Lanwei -- eine prospektive Studie.

BACKGROUND: In almost all Western industrial nations, appendicitis is the most frequent cause for acute abdomen. Nevertheless, the diagnosis of appendicitis is often difficult, which manifests in highly negative laparotomy rates. In a prospective study we aimed to investigate if palpation of the acupuncture point Lanwei (extra point 22, extra point 33) which is located on the right leg may increase the accuracy in the diagnosis of appendicitis. PATIENTS AND METHODS: Presurgically, the Lanwei point was examined for reproducible tenderness on 116 cooperative nonanesthetized patients admitted to hospital for suspected appendicitis. The results were compared with those of histological diagnosis. The examination of tenderness of the Lanwei sign was performed without knowing the results of other examinations. Additionally, other signs and laboratory parameters for appendicitis were examined using a standardized documentation form. Altogether, 17 presurgical variables, 18 clinical signs, and 3 tests were evaluated. RESULTS: A positive Lanwei sign was documented in 65 cases (56%), whereas 51 patients (44%) had a negative Lanwei sign. 65 of the 116 patients were operated. 59 of those had a histologically proven appendicitis. The sensitivity of the Lanwei sign was 64.4%, specificity ranged at 50%. Rates for positive and negative predictive values were 92.7% and 12.5%, respectively. Odds ratio was estimated as 1.8. When comparing these parameters, the Lanwei sign ranged between the 7th and 10th place of the 22 most important clinical signs for appendicitis. The negative laparotomy rate was 9%, of which 4 of 6 patients had other indications for an operation. The rate of perforation was 15%. CONCLUSION: Compared with many conventional signs for appendicitis as for example Mc Burney, tender Sherren triangle, reduced peristalsis, the diagnostic value of the Lanwei sign is not sufficient. Although a reproducible positive Lanwei sign is a good hint for a true appendicitis, in case of a negative Lanwei sign the probability for an appendicitis may be relatively high. Because of the low negative predictive value, the Lanwei sign is not suitable for reducing negative laparatomy rates. As in many other studies, the one and only indicator for appendicitis which yields high results in all statistical parameters was not detected in this study. In comparison to the statistical parameters of traditional signs for appendicitis, the Lanwei sign cannot be regarded as a good diagnostic parameter for appendicitis.

[Jejunum interposition as replacement of the pars descendens duodeni in extensive tubulovillous adenoma]. / Jejunuminterponat als Ersatz der Pars descendens duodeni bei ausgedehntem tubulovillösen Adenom.

Reconstruction after partial duodenectomy with resection of the ampulla of Vater is often troublesome. We report the case of a 70-year-old patient with endoscopically non-resectable tubulo-villous adenoma of the descending duodenum including the ampulla of Vater in which subsequent biopsies revealed dysplastic areas. A partial resection of the descending duodenum including the ampulla of Vater was performed. Reconstruction was achieved by the interposition of a jejunal limb in which the ampulla could be reinserted to the posterior wall. The postoperative course was uneventful; a carcinoma was not found within the specimen. In cases of widespread adenomas of the ampulla of Vater, duodenum-preserving resection by interposition of a jejunal limb with reinsertion of the ampulla into the posterior wall may be used as an alternative to Roux-Y reconstruction and to Whipple's procedure.

[Laparoscopic colon surgery]. / Laparoszkópos vastagbélsebészet.

We review our experience in laparoscopic colorectal surgery, with indications, technical aspects and results. Between 1992 and 31/12/2000, we performed 113 laparoscopic or laparoscopically assisted colorectal operations. Of 79 malignant cases, 37 operations were oncologically radical and therapeutic, 42 were palliative. During the immediate postoperative period two deaths occurred (2.8%), the causes of death were not related to surgery. Port site metastasis developed in one patient (1.4%). Postoperative complications developed in 18 patients (14.5%). Only one patient required conversion to laparotomy. We emphasize the importance of hand assisted laparoscopic surgery (HALS) in laparoscopic colorectal surgery, because it can increase the number of laparoscopic colorectal operations. Based on our results and experience, we recommend the routine use of laparoscopic technique in colorectal surgery.

Evidence for cross-talk between glycoprotein VI and Gi-coupled receptors during collagen-induced platelet aggregation.

Collagen-induced platelet aggregation is a complex process and involves synergistic action of integrins, immunoglobulin (Ig)-like receptors, G-protein-coupled receptors and their ligands, most importantly collagen itself, thromboxane A(2) (TXA(2)), and adenosine diphosphate (ADP). The precise role of each of these receptor systems in the overall processes of activation and aggregation, however, is still poorly defined. Among the collagen receptors expressed on platelets, glycoprotein (GP) VI has been identified to play a crucial role in collagen-induced activation. GPVI is associated with the FcRgamma chain, which serves as the signal transducing unit of the receptor complex. It is well known that clustering of GPVI by highly specific agonists results in platelet activation and irreversible aggregation, but it is unclear whether collagen has the same effect on the receptor. This study shows that platelets from Galphaq-deficient mice, despite their severely impaired response to collagen, normally aggregate on clustering of GPVI, suggesting this not to be the principal mechanism by which collagen activates platelets. On the other hand, dimerization of GPVI by a monoclonal antibody (JAQ1), which by itself did not induce aggregation, provided a sufficient stimulus to potentiate platelet responses to Gi-coupled, but not Gq-coupled, agonists. The combination of JAQ1 and adrenaline or ADP, but not serotonin, resulted in alpha(IIb)beta(3)-dependent aggregation that occurred without intracellular calcium mobilization and shape change in the absence of Galphaq or the P2Y(1) receptor. Together, these results provide evidence for a cross-talk between (dimerized) GPVI and Gi-coupled receptors during collagen-induced platelet aggregation. (Blood. 2001;97:3829-3835)

Rhodocytin (aggretin) activates platelets lacking alpha(2)beta(1) integrin, glycoprotein VI, and the ligand-binding domain of glycoprotein Ibalpha.

Although alpha(2)beta(1) integrin (glycoprotein Ia/IIa) has been established as a platelet collagen receptor, its role in collagen-induced platelet activation has been controversial. Recently, it has been demonstrated that rhodocytin (also termed aggretin), a snake venom toxin purified from the venom of Calloselasma rhodostoma, induces platelet activation that can be blocked by monoclonal antibodies against alpha(2)beta(1) integrin. This finding suggested that clustering of alpha(2)beta(1) integrin by rhodocytin is sufficient to induce platelet activation and led to the hypothesis that collagen may activate platelets by a similar mechanism. In contrast to these findings, we provided evidence that rhodocytin does not bind to alpha(2)beta(1) integrin. Here we show that the Cre/loxP-mediated loss of beta(1) integrin on mouse platelets has no effect on rhodocytin-induced platelet activation, excluding an essential role of alpha(2)beta(1) integrin in this process. Furthermore, proteolytic cleavage of the 45-kDa N-terminal domain of glycoprotein (GP) Ibalpha either on normal or on beta(1)-null platelets had no significant effect on rhodocytin-induced platelet activation. Moreover, mouse platelets lacking both alpha(2)beta(1) integrin and the activating collagen receptor GPVI responded normally to rhodocytin. Finally, even after additional proteolytic removal of the 45-kDa N-terminal domain of GPIbalpha rhodocytin induced aggregation of these platelets. These results demonstrate that rhodocytin induces platelet activation by mechanisms that are fundamentally different from those induced by collagen.

Glycoprotein VI but not alpha2beta1 integrin is essential for platelet interaction with collagen.

Platelet adhesion on and activation by components of the extracellular matrix are crucial to arrest post-traumatic bleeding, but can also harm tissue by occluding diseased vessels. Integrin alpha2beta1 is thought to be essential for platelet adhesion to subendothelial collagens, facilitating subsequent interactions with the activating platelet collagen receptor, glycoprotein VI (GPVI). Here we show that Cre/loxP-mediated loss of beta1 integrin on platelets has no significant effect on the bleeding time in mice. Aggregation of beta1-null platelets to native fibrillar collagen is delayed, but not reduced, whereas aggregation to enzymatically digested soluble collagen is abolished. Furthermore, beta1-null platelets adhere to fibrillar, but not soluble collagen under static as well as low (150 s(-1)) and high (1000 s(-1)) shear flow conditions, probably through binding of alphaIIbbeta3 to von Willebrand factor. On the other hand, we show that platelets lacking GPVI can not activate integrins and consequently fail to adhere to and aggregate on fibrillar as well as soluble collagen. These data show that GPVI plays the central role in platelet-collagen interactions by activating different adhesive receptors, including alpha2beta1 integrin, which strengthens adhesion without being essential.