Moderate Adhesion Research Articles

Characterization and properties of low-friction, multilayered Cr-doped diamond-like carbon coatings prepared by pulse biased filtered cathodic arc deposition

The aim of the article was to investigate the effect of pulsed high-voltage bias on phase composition, surface morphology, mechanical properties, and the tribological performance of the multilayered Cr/CrN/DLC coatings prepared by the filtered cathodic arc deposition (FCAD) process. The coatings were deposited using a laboratory arc source device equipped with two macroparticle filtering systems. All coatings were deposited at substrate temperatures below 200°C. Cr/CrN/DLC multilayered coatings were analysed using X-ray photoelectron spectroscopy, a glow discharge optical emission spectrometry technique, scratch testing, nano-indentation measurements (nano-hardness and Young's modulus), and optical microscopy. Tribological tests employing a ball-on-disc tribosystem were performed in dry friction conditions in an air-conditioned room (RH 50 per cent, 23°C). The results proved that the substrate bias voltage exerts a significant influence on the mechanical properties of the Cr/CrN/DLC multilayered coatings by the changing chemical composition of the DLC top layers. With an increase of bias voltage from 2 to 6 kV, the Cr content increases from 2 to 4 per cent and the sp2/sp3 ratio decreases from 1.06 to 0.44. The Cr-doped DLC multilayered coatings were characterized by a very smooth surface, a low friction coefficient (0.13–0.15), moderate hardness (8–11 GPa), and a Young's modulus of 95–130 GPa. Due to the moderate adhesion strength of DLC top layers, their wear resistance was not satisfactory for real applications. In each tribological test, the delaminating process of the DLC layers was observed after approximately 200–300 load cycles. To improve the mechanical properties and adhesion of a DLC layer, the optimization of the transition and DLC layers is achieved by changing the parameters of the physical vapour deposition process.

A comparative study for lung biopsy in dogs

This study was conducted to compare two techniques for obtaining lung biopsy in dogs. Twelve adult dogs from both sexes were used in this study. The animals were divided into two groups, each group contained six dogs. In both groups, the animals were applied under right thoracotomy for lung biopsy collection from the middle lobe. In group one the lung biopsy was obtained by removal of a piece of lung tissue with a scalpel and the cut edge was sutured by two rows of continuous horizontal matters and simple continuous patterns where as in group two the biopsy was collected using a therom-cautery device and the cut edge was left without suturing. Gross and histopathological changes were examined on postoperative days 15 and 30. The gross pathological changes in group one after 15 day revealed presence of severe adhesions between the cutting site and pleura where as the adhesion was less after 30 postoperative day. The pulmonary tissue at site of biopsy collection relatively became hard especially near the suture line. Group two showed no adhesion on postoperative day 15 but the adhesion appeared on postoperative day 30 between the sites of cauterization with the other lung lobes which varied from simple to moderate adhesion while the lung tissue at cauterization site had approximately the same consistency of normal lung tissues. The histopathlogical changes in group one was characterized by formation of inflammatory nodules and high infiltration of inflammatory cells particularly polymorphonucular cells with presence of pulmonary hemorrhage and edema in the cutting site. Group two showed lesser histopathological changes and they were associated with lesser mononuclear inflammatory cells where as hemorrhage and edema were not developed on the cutting site. In conclusion, the use of thermo-cautery device to obtain the lung biopsy is simple, fast, less invasive and more aseptic than use the cutting and suturing method.

Regulation of Cell-Surface Adhesion During Amoeboid Migration

During amoeboid migration, cell-substrate interactions play a critical role by supplying the traction allowing a cell to move itself forward. It has been shown that the ability of individual mammalian cells to move will depend on their adhesiveness to that surface, with moderately adhesive surfaces being ideal: moderate adhesion allows cells to gain traction to move forward while still permitting detachment of the cell rear. In addition to cell-substrate adhesion, migrating cells often experience cell-cell adhesion, and in many systems (such as wound healing or embryogenesis) such adhesion can dominate. The amoeba Dictyostelium discoideum naturally exhibits both cell-substrate and cell-cell adhesion during the aggregation process. We used both high- and low-magnification time-lapse microscopy to investigate the individual and collective migration of D. discoideum on substrates of varying adhesiveness, as well as on interfaces between substrates. We find that non-ideal adhesive surfaces can affect both individual cell migration as well as the behavior of cell groups. At the population scale, non-ideal surfaces slow down the initiation of aggregation and change how the process is performed: instead of forming large aggregation centers, the population forms small aggregation centers which coarsen over time until the standard aggregation center size is eventually reached. At the scale of single cells, we measure both adhesion ability as well as the area of contact between cells and surface for individual cells and cells that are part of groups. On all surfaces the contact area oscillates, reflecting the migration dynamics. Surprisingly, comparable forces are needed to rip cells off all surfaces, indicating that surface adhesion may be regulated by the cells.

Effect of submucosa of small intestine on intestinal anastomosis in goats

The aim of this study was to investigate the effect of small intestinal submucosa (SIS) on the healing of intestinal anastomosis in goats. Twelve local breed bucks were used. Animals were divided into two equal groups, in the first group the anastomotic site after resection of 4 cm from the jejunum was sutured by horizontal mattress pattern, considered as a control group. In the second group, after anastomose was covered by small intestinal submucosa,prepared previously and fixed with the anastomotic site by multiple stitches of a simple interrupted suture. Experimental animals were observed clinically, after 15 and 30 days postoperation, the sample of anastomosis site were examined grossly and histopathologically. Grossly in control group moderate to severe adhesion of anastomotic site with the surrounding tissue was found as compared with the moderate adhesion in the treated group. The bursting pressure, in control group, was (150±2.9) and (178.3±4.5) mmHg, while in the treated group was (185±2.9) and (208.3±4.5) mmHg at a period of 15 and 30 days post operation respectively. The degree of stenosis in control group was (59±1.5) and (49±2.2), while in the treated group was (76±5.6) and (36.3±0.6) at a period of 15 and 30 days post operation respectively. The histopathological findings revealed that the healing process was more prominent in the treated group than in the control group. In conclusion of this study investigated that submucosa of small intestine enhances healing of intestinal anastomosis.

Chemically modified chitosan anti-adhesion membrane preventing postoperative pericardial adhesions in rabbit myocardial infarction model

Objective To evaluate the efficacy of a chemically modified chitosan anti-adhesion membrane for preventing postoperative pericardial adhesions in rabbit myocardial infarction model. Methods Twenty-five Japanese white rabbits underwent myocardial infarction by ligation of coronary artery after thoracotomy, and devided into treatment and control groups randomly. The treatment group had a chitosan anti-adhesion membrane placed between the heart and retrostemal injured surfaces, while control group received nothing. Then Chest was subsequently closed. Eleven rabbits survived the operation in each group. After a period of 3 months, there were 8 rabbits alive in control group and 9 rabbits alive in treatment group. The animals were examined by Cine magnetic resonance imaging. sacrificed under anesthesia, and independent observers, blinded to treatment, graded the formation of pericardial adhesions by magnetic resonance cinema and histologioal anatomy respectively. Data were analyzed by Wilcoxon' s rank test. Results Cine magnetic resonance imaging revealed that there were 2,2,4 cases of mild adhesion, moderate adhesion,and severe adhesion in group, and 7, 2, 0 respectively (P<0.05). Thoracotomy indicated there were 1,1,2,4 cases of adhesions, mild adhesions, moderate adhesions, and severe adhesions in group A, and 3, 4, 2, 0 in group B respectively (P < 0. 05). Conclusion Placement of a chemically modified chitosan anti-adhesion membrane between injured surfaces effectively reduced the formation of postoperative pericardial adhesion in rabbits of myocardial infarction model. Key words: Myocardial infarction; Model, animal; Tissue adhesions; Chitosan; Magnetic resonance imaging

Do gastrotomies require repair after endoscopic transgastric peritoneoscopy? A controlled study

The optimal method for closing gastrotomies after transgastric instrumentation has yet to be determined. To compare gastrotomy closure with endoscopically delivered bioabsorbable plugs with no closure. Prospective, controlled study. Animal laboratory. Twenty-three dogs undergoing endoscopic transgastric peritoneoscopy between July and August 2007. Endoscopic anterior wall gastrotomies were performed with balloon dilation to allow passage of the endoscope into the peritoneal cavity. The plug group (n = 12) underwent endoscopic placement of a 4 x 6-cm bioabsorbable mesh plug in the perforation, whereas the no-treatment group (n = 11) did not. Animals underwent necropsy 2 weeks after the procedure. Complications related to gastrotomy closure, gastric burst pressures, relationship of burst perforation to gastrotomy, and the degree of adhesions and inflammation at the gastrotomy site. After the gastrotomy, all dogs survived without any complications. At necropsy, burst pressures were 77 +/- 11 mm Hg and 76 +/- 15 mm Hg (P = .9) in the plug group and no-treatment group, respectively. Perforations occurred at the site of the gastrotomy in 2 of 12 animals in the plug group and in none of the 11 dogs in the no-treatment group (P = .5). Finally, there were minimal adhesions in all dogs (11/11) in the no-treatment group and minimal adhesions in 3 and moderate adhesions or inflammatory masses in 9 of the 12 animals in the plug group (P = .004). Small number of subjects, animal model, no randomization. Gastrotomy trauma during short peritoneoscopy may not be applicable to longer procedures. After endoscopic gastrotomy, animals that were left untreated did not show any clinical ill effects and demonstrated adequate healing, with fewer adhesions and less inflammation compared with those treated with a bioabsorbable plug.

Halofuginone- and Chitosan-Coated Amnion Membranes Demonstrate Improved Abdominal Adhesion Prevention

Our objective was to determine whether coating the amniotic membrane with halofuginone, a type 1 collagen synthase inhibitor, with or without the hemostasis-inducing substance chitosan, reduced the number and severity of adhesions in the rat uterine horn injury model. Sixty retired breeder Sprague-Dawley rats underwent midline laparotomy and a zone of ischemia was created in the left uterine horn of each animal. Rats were randomized to one of six treatment groups: (1) untreated control, (2) oxidized regenerated cellulose (Interceed®) (ORC), (3) plain amnion, (4) amnion coated on both sides with 0.5% solution of halofuginone (HAH), (5) amnion coated on one side with 0.5% halofuginone and on the other side with chitosan (CAH), or (6) amnion coated on both sides with chitosan (CAC). The zone of ischemia in each left uterine horn was wrapped in each treatment. Rats were sacrificed 2 weeks after laparotomy, and adhesions were counted and scored for severity. Data were analyzed using Chi square and a p <0.05 was considered significant. Our results showed that there were no differences in the percentage of animals with adhesions in the untreated, ORC, plain amnion, or CAC groups. No adhesions formed in any animal in the HAH group and only 14% of the animals developed adhesions to the uterine horn in the CAH group (p < 0.05). The percentage of animals with moderate and severe adhesions did not differ between untreated controls and the ORC groups, but were significantly reduced in all four of the amnion groups: plain amnion, HAH, CAH, and CAC (p < 0.05). Amnion coated with halofuginone alone or in combination with chitosan reduced the percentage of animals with adhesions, as well as the percentage of animals with moderate and severe adhesions compared to untreated controls and the ORC group in the rat uterine horn injury model. Amnion alone or coated with chitosan reduced the percentage of rats with moderate and severe adhesions, but not the percentage of rats with adhesions of any type compared to both untreated controls and the ORC group in the rat uterine horn injury model.

Molecular Simulation of Atrazine Adhesion and Diffusion in a Saturated Sand Model

This paper presents an extensive study about atrazine behavior in saturated sands by the aid of molecular simulation techniques. Systems have been described in a simplified way to predict adhesion and diffusion phenomena, and to give useful insights at the atomistic level. Diffusion coefficients, binding energies, and concentration profiles have been determined as a function of interlayer distances and atrazine concentration. Combined Monte Carlo, Molecular Mechanics, and Molecular Dynamics techniques have been used. In silico results have been compared with available experimental data for validation, and with similar in silico experiments, finding a good agreement. Results confirm a moderate atrazine adhesion onto silica framework and a more favorable tendency to bind with water. Atrazine diffusion has been found to be influenced by concentration and interlayer distance. Encouraging results show how these techniques can be generalized and made applicable for soil contamination modelling at the atomistic level in a more extensive way.

Study on transvaginal hydrolaparoscopic pelvic adhesiolysis in the infertile women

To investigate the safety and efficacy of transvaginal hydrolaparoscopic pelvic adhesiolysis (THLPA) treatment in the infertile women. From May 2007 to Sep. 2008, 30 infertile patients underwent THLPA. The dye-test, hysteroscopy, and dye-test using catheterization of tubal ostium by hysteroscopy were performed at the same time. Pelvic adhesions were scored according to the revised American Fertility Society classification of endometriosis (1985). The adhesions were graded as mild (score 1-9), moderate (10-19), and severe (>/= 20). Twenty-four cases were in mild adhesions, 5 moderate adhesions, and 1 severe adhesion. The duration of the operation and discharge, pelvic adhesions score, tubal patency, complications, and pregnancy rate were investigated. (1) THPLA: the majority of pelvic adhesions in all patients were successfully performed adhesiolysis. Only a little filmy adhesions of proximal peritube of 7 tubes and proper ligament of 5 ovaries and cohesive adhesions of 4 ovaries did not underwent surgical lysis. (2) Tubal patency: 35 tubes were of proximal occlusion by dye-test, of which 21 (60%, 21/35) were unobstructed and 4 (11%, 4/35) were partly unobstructed after the dye-test using catheterization of the tubal ostium by hysteroscopy. (3) The duration of operation: the overall operative time were (32 +/- 6) minutes in mild adhesion, (52 +/- 6) minutes in moderate adhesion, and 83 minutes in severe adhesion. Of which the time of THLPA were (11 +/- 5) minutes in mild adhesion, (35 +/- 7) minutes in moderate adhesion, and 62 minutes in severe adhesion, respectively. (4) The duration of discharge: the postoperative discharge time was 120 - 175 minutes. No complications occurred. (5) The rate of pregnancy: in the (15.8 +/- 4.3) months' follow-up, the rate of pregnancy was 45% (13/29), which one patient lost follow-up. THLPA is safe, efficacious and not being hospitalized management. When compared with laparoscopy, it is simpler, more economic, and less minimally invasive approach. The appropriate indication of THLPA is to treat filmy, especially mild pelvic adhesions. It could partly avoid transabdominal operative laparoscopy for the infertile women.

Subsequent abdominal surgery after laparoscopic ventral and incisional hernia repair with an expanded polytetrafluoroethylene mesh: a single institution experience with 72 reoperations

PurposeLaparoscopic ventral and incisional hernia repair (LVIHR) carries a risk of adhesion formation and can influence subsequent abdominal operations (SAOs). We performed a retrospective study of findings during reoperations of patients who had previously had an LVIHR by using an expanded polytetrafluoroethylene mesh (DualMesh®; WL Gore, Flagstaff, AZ, USA).MethodsThe medical records of all 695 patients who had LVIHR at our hospital were reviewed. Patients who underwent SAO for various indications were identified (n = 72) and analyzed.ResultsSeven LVIHR patients (1%) had early SAO (within a few days). In six patients (86%), removal of the mesh was required. Intra-operatively, in all six of these patients with peritonitis, there were no adhesions against the implant identified. Late SAOs (after more than 1 month) were performed in 65 patients (9.4%). Only one patient required acute surgical intervention due to an LVIHR-related adhesion (0.15%). Laparoscopy was performed in 83% and laparotomy in 17% of patients. Adhesions against the implant were present in 83% of patients; in 65%, the adhesions involved omentum only, and in 18%, they involved the bowel. Adhesiolysis was always easy and caused no inadvertent enterotomies. SAOs were devoid of postoperative complications.ConclusionsIn this largest series of reoperations after LVIHR, the majority of patients had mild or moderate adhesions against the implant. The specific observations that: (1) no relaparoscopies had to be converted, (2) no inadvertent enterotomies were made during adhesiolysis, and (3) SAOs have practically been devoid of peri- and postoperative complications indicate that SAOs can be safely performed after previous LVIHR with DualMesh.

Study on incidence and associated factors of different degree endometrioma adhesions

To investigate the relationship between degree of endometrioma adhesions and clinical feature, surgical treatment and postoperative recurrence. From Jan 2003 to Mar 2008, 662 patients with endometrioma undergoing laparoscopic ovarian endometrioma excision in Peking Union Medical College Hospital were studied retrospectively. All patients were classified into four groups according to the extent of adhesions: 31 cases in none adhesions group, 123 cases in mild adhesions group (filmy thickness, avascular, easily separated adhesions), 310 cases in moderate adhesions group (less than a half of ovary was adjacent to dense thickness adhesions which was difficult to separate, or above a half of ovary were adjacent to filmy thickness adhesions) and 198 cases in severe adhesions group (above a half of ovary was adjacent to dense thickness, well vascularized adhesions which was difficult to separate, and always involved the other pelvic organs, observed angiogenesis). The comparison of degree, characteristics, period of pain, lab test, surgical management and postoperative recurrence was performed among those above groups. In the mean time, risk factors and multinomial logistic regression were analyzed. (1) Clinical characteristics: The incidence of patients with dysmenorrhea, dyspareunia, straining feeling in anus, chronic pelvic pain and the level of CA(125) (> 35 kU/L) was remarkably higher in moderate-to-severe adhesion groups than in none-to-mild adhesions groups (P = 0.000, 0.000, 0.001, 0.006 and 0.000, respectively). Infertility rate were significantly higher in severe adhesions group (15.7%, 31/198) than none adhesions group (3.2%, 1/31), mild adhesions group (11.4%, 14/123) and moderate adhesions group (9.7%, 30/310, OR = 1.728, P < 0.05). (2) Operating time and blood loss: Operating time of each groups was as followed: (37 +/- 15) min in none adhesions group, (42 +/- 19) min in mild adhesions group, (50 +/- 20) min in moderate adhesions group and (63 +/- 22) min in severe adhesion group. Blood loss was (23 +/- 12) ml in none adhesion group, (31 +/- 27) ml in mild adhesion group, (40 +/- 32) ml in moderate adhesion group and (70 +/- 67) ml in severe adhesions group. Thicker adhesions result in longer operation time and more blood loss. (3) Combined with other disease: The ratio of patients who combined with adenomyosis or deeply infiltrating endometriosis in moderate-to-severer adhesion groups was higher than patients in none-to-mild adhesions groups (OR = 3.466, P = 0.000). (4) Postoperative recurrence: It was categorized into recurrence of pain and cyst. Moderate-to-severe adhesions was related to higher recurrence rate of pain (OR = 1.685, P = 0.046), but was irrelevant to recurrence of cyst. The more extent of endometrioma adhesions was related to severer pelvic pain symptoms, longer operating time and more blood loss. Postoperative pain recurrence rate was observed in moderate-to-severe adhesion group. Extent of adhesions was irrelevant to cyst recurrence.

A comparative study on adhesion and recovery of potential probiotic strains ofLactobacillusspp. byin vitroassay and analysis of human colon biopsies

Adhesion of the new Lactobacillus isolates, L. casei D12, L. casei Q85, L. casei Z11 and L. plantarum Q47, to the porcine intestinal cell line IPEC-J2 was investigated and compared to the recovery of the same bacterial strains from colon biopsies and faeces obtained from human intervention studies. Probiotic bacteria L. rhamnosus 19070, L. reuteri 12246 and L. casei F19 were used as reference strains. The new isolates exhibited low to moderate adhesion to IPEC-J2 cells in the range of 7-26%. A large variation in the recovery of strains was observed between the persons, suggesting host specificity of intestinal colonization. High correlation was shown between recovery from the different sections of the colon of the same subject, indicating consistency of bacterial colonization of the epithelium. The recovery of L. casei Z11 and L . casei Q85 was highest and comparable to the reference strains of L. rhamnosus 19070 and L. casei F19, indicating their potential to colonize the human intestine. Analysis of linear regression demonstrated poor correlation between in vitro and in vivo results, emphasizing the importance of critical evaluation of in vitro adhesion data for prediction of bacterial colonization of the gut. Key words: Lactobacillus, adhesion, recovery, colon biopsies

&lt;i&gt;In Vitro&lt;/i&gt; and Clinical Evaluation of an Oral Mucosal Adhesive Film Containing Indomethacin

To develop a new mucoadhesive film containing an analgesic combining clinical efficacy and patient comfort, we prepared and evaluated a two-layered film consisting of an adhesive layer containing indomethacin (IM) as the active ingredient and carboxyvinyl polymer (CP) as a bonding agent and a nonadhesive layer containing polyethylene glycol (PEG) to improve film texture. In in vitro and in vivo adhesive tests, the optimal concentration of CP that could be applied to the mucous membrane was 0.2% or 0.3%. Stability testing determined that the optimal storage conditions and expiration period were 4 degrees C without shade and 4 weeks, respectively. The film was clinically evaluated in patients with oral pain. IM at concentrations of 0.5% and 1% provided optimum analgesic effects, and the effects were the greatest in the 1% IM group. The addition of PEG to the nonadhesive layer reduced the number of patients experiencing discomfort at the site where the film was applied. Therefore this film formulation may be useful for local analgesic application due to its low dose requirement, moderate adhesion, and comfortable texture.

Simulation of curving at low speed under high traction for passive steering hauling locomotives

The traction control in modern electric and diesel electric locomotives has allowed rail operators to utilise high traction adhesion levels without undue risk of damage from uncontrolled wheel spin. At the same time, some locomotive manufacturers have developed passive steering locomotive bogies to reduce wheel rail wear and further improve locomotive adhesion performance on curves. High locomotive traction loads in curving are known to cause the loss of steering performance in passive steering bogies. At present there are few publications on the curving performance of locomotive steering with linkage bogies. The most extreme traction curving cases of low speed and high adhesion for hauling locomotives have not been fully investigated, with effects of coupler forces and cant excess being generally ignored. This paper presents a simulation study for three axle bogie locomotives in pusher and pulling train positions on tight curves. The simulation study uses moderate and high traction adhesion levels of 16.6% and 37% for various rail friction conditions. Curving performance is assessed, showing forced steering bogies to have considerable advantages over self steering bogies. Likewise it is shown that self steering bogies are significantly better than yaw relaxation bogies at improving steering under traction. As the required traction adhesion approaches the rail friction coefficient, steering performance of all bogies degrades and yaw of the bogie frame relative to the track increases. Operation with excess cant and tensile coupler forces are both found to be detrimental to the wear performance of all locomotive bogies, increasing the bogie frame yaw angles. Bogie frame pitching is also found to have significant effect on steering, causing increased performance differences between bogie designs.

Synthesis, thermal characterization, and gas barrier properties of UV curable organic/inorganic hybrid nanocomposites with metal alloys and their application for encapsulation of organic solar cells

We have successfully prepared ultraviolet (UV) curable organic/inorganic hybrid nanocomposites with good thermal stability, moderate adhesion strength, and excellent barrier capability. In order to improve the gas blocking properties, the metal alloy (Invar) has been blended with lab-made organic/inorganic hybrid nanocomposites, dramatically not only raising the gas resistance but also reducing the shrinkage after UV curing. Moreover, we have also applied lab-made nanocomposite IV for the encapsulation of organic solar cells. The experimental results reveal that introduction of nanocomposite IV can effectively block the penetration of moisture as well as oxygen in the air into the devices and consequently promote the lifetime of organic solar cells.

Dynamic Bone Quality-A Non-Invasive Measure of Bone's Biomechanical Property

Carbon-based electroactive polymers (EAPs) are core materials for actuator applications. Introducing conductive fillers into EAPs is considered an effective method to improve the actuating performance, due to the enhanced dielectric properties achieved. This work describes the elaboration and characterization of polyurethane (PU)/oxygen-functionalized graphene (OFG) composite films. Results revealed that for the nanocomposites, a large increase in dielectric constant was obtained without a great mechanical reinforcement, whereas there was no improvement in electromechanical performance as compared to pure polyurethane. The possible reasons for these discordant results were thus investigated with the help of multiscale studies. The importance of measuring the dielectric and mechanical properties under the same conditions as those used to drive actuators could be pointed out. Using high electric field values led to a better prediction of the electromechanical coefficient M31 for pure PU at low frequency, but did not completely explain the decreasing M31 found for the composites. The discrepancy could be due to the moderate adhesion between the polymer and the graphene nanoplatelets, but also to the competition between the increased dielectric constant and the decreased electric field seen by the polymer, induced by MWS interfacial polarization.

Transatrial Repair of Submitral Left Ventricular Pseudoaneurysm

In a 57-year-old man with Wolff-Parkinson-White syndrome, a left ventricular pseudoaneurysm developed, induced by the pop phenomenon, after radiofrequency catheter ablation of the posterolateral accessory pathway. The pseudoaneurysm was positioned at the atrioventricular groove with moderate pericardial adhesions, and the rupture site was located just below the P3 annulus of the posterior mitral leaflet. With this anatomy and in the presence of adhesions, we repaired the rupture site from within the heart through an incision made in the posterior mitral leaflet. This transmitral approach might be a reasonable surgical option for treating this type of submitral left ventricular pseudoaneurysm.

Role of Streptococcus gordonii Surface Proteins SspA/SspB and Hsa in Platelet Function

Streptococcus gordonii colonization of damaged heart surfaces in infective endocarditis is dependent upon the recognition of host receptors by specific bacterial surface proteins. However, despite several attempts to identify the mechanisms involved in this interaction, the nature of the bacterial proteins required remains poorly understood. This study provides clear evidence that several S. gordonii surface proteins participate in the interaction with platelets to support platelet adhesion and induce platelet aggregation. S. gordonii strains were found to support strong (DL1-Challis, SK12, SK184, and Blackburn) or moderate (UB1545 delta hsa and CH1-Challis) adhesion or failed to support platelet adhesion (M5, M99, and Channon). In addition, under flow conditions, platelets rolled and subsequently adhered to immobilized S. gordonii at low shear (50 s(-1)) in an Hsa-dependent manner but did not interact with S. gordonii DL1 at any shear rate of >50 s(-1). S. gordonii strains either induced (DL1-Challis, SK12, SK184, UB1545 delta hsa, and M99) or failed to induce (M5, CH1-Challis, Channon, and Blackburn) platelet aggregation. Using a proteomic approach to identify differential cell wall protein expression between aggregating (DL1) and nonaggregating (Blackburn) strains, we identified antigen I/antigen II family proteins SspA and SspB. The overexpression of SspA or SspB in platelet-nonreactive Lactococcus lactis induced GPIIb/GPIIIa-dependent platelet aggregation similar to that seen with S. gordonii DL1. However, they failed to support platelet adhesion. Thus, S. gordonii has distinct mechanisms for supporting platelet adhesion and inducing platelet aggregation. Differential protein expression between strains may be important for the pathogenesis of invasive diseases such as infective endocarditis.

Aggravation of Different Types of Experimental Colitis by Depletion or Adhesion Blockade of Neutrophils

Neutrophils are generally thought to play an important proinflammatory role in the pathogenesis of inflammatory bowel disease. The objective of this study was to evaluate whether blocking the invasion of neutrophils by anti-L-selectin monoclonal antibodies modulates chemically induced colitis and how this modulation is accomplished. Trinitrobenzene sulfonic acid/dinitrobenzene sulfonic acid (TNBS/DNBS)-induced colitis was studied in rats on treatment with anti-L-selectin monoclonal antibodies (mAb) or antineutrophil antiserum. Different anti-L-selectin mAb, either blocking or nonblocking, as well as F(ab)(2) fragments were evaluated. Additionally, leukocyte migration was examined using intravital microscopy. Furthermore, the effect of neutrophil depletion in rat TNBS-induced colitis was studied either prior to or after colitis induction as well as murine CD4(+)CD45RB(high) transfer colitis. Finally, bacterial translocation during DNBS-induced colitis was studied in neutrophil-depleted and control rats. Anti-L-selectin mAb treatment resulted in increased mortality and bowel inflammation as well as hemorrhagic eye secretion. No clear difference was found between blocking and nonblocking mAb or F(ab)(2) fragments. For all investigated antibodies/fragments, either complete blockade of leukocyte invasion or marked neutrophil depletion was found. Accordingly, neutrophil depletion by antiserum resulted in aggravation of rat DNBS-induced colitis as well as murine transfer colitis. Adhesion blockade or neutrophil depletion aggravates rat TNBS/DNBS-induced colitis together with extraintestinal manifestations of the eyes. Therefore, neutrophils appear to have an important role in mucosal repair processes. Importantly, adhesion blockade as a therapeutic concept can be detrimental in inflammatory bowel disease.

Antiadhesive effects of mitomycin C and streptopeptidase A in rats with intraperitoneal adhesions

Intraabdominal adhesion formation is a frequent problem after major abdominal surgery. For many years, there have been various attempts to decrease adhesions by using systemic and local drugs and mechanical barriers. In this study we aimed to evaluate the antifibrinolytic antiadhesive effects of mitomycin C (MMC) and streptopeptidase A (SA) against intraabdominal adhesions. Forty-eight rats were divided into six groups, each with eight rats. Group 1 (sham group) rats were laparotomized by transverse incision only. In Group 2 (laparotomy and talcum powder), 2 ml talcum powder was scattered equally onto the intestinal surface after laparotomy. Group 3 (SA only), 2 g SA was introduced onto the intestinal surface. Group 4 (talcum powder and SA), 2 ml talcum powder was scattered onto the intestinal surface and then 2 g SA was applied on the same area. Group 5 (MMC only), 2 ml MMC was introduced onto the intestinal surface. Group 6 (talcum powder and MMC), 2 ml talcum powder was scattered onto intestinal surface and then MMC was applied onto same area. We assessed adhesion grades macroscopically, as well as, hydroxproline levels biochemically. Macroscopicaly, the number of rats with moderate or severe adhesions was significantly higher in the control group than all other groups (P < 0.05). SA and MMC groups had only mild adhesions. No intraabdominal problem was detected in rats with SA or MMC. Hydroxyproline (HP) levels were significantly higher in control group than all other groups (P < 0.05). There was no statistical significance between the rats with SA and MMC (P > 0.05) according to the HP measurements. MMC and SA may have potential antiadhesive effects. Both substances could be beneficial against adhesion formation after laparotomies.