Wall Defects Research Articles

Mechanical Properties of CVD Grown Multi-walled Carbon Nanotubes (MWNTs)

ABSTRACTWe have measured the bending modulus of several different CVD (chemical vapor deposition) grown MWNTs using a vibrating reed technique. The MWNTs are produced from a thermal decomposition of three different precursors: (i) xylene/ferrocene, (ii) xylene/ferrocene/melamine (nitrogen-doped), and (iii) trimethylamine (TMA)/ferrocene. The first two precursors are used to compare the mechanical properties of typical CVD-grown to bamboo-type MWNTs. Nanotubes prepared using the third precursor shows relatively fewer walls (∼ 4–20 compared to ∼15–40)) and defects compared to those prepared from the xylene/ferrocene mixture. The resonant frequencies of these nanotubes were measured optically in air using a dark field light microscope. The diameters of these nanotubes range from 50 – 160 nm as determined from TEM and the average length is ∼ 10 microns. For the xylene/ferrocene and trimethylamine/ferrocene tubes, the average bending modulus is estimated to be 0.1 and 0.3 TPa, respectively. However, the bending modulus for the nitrogen-doped tubes is ∼9 GPa which is significantly lower compared to regular MWNTs implying that the bending modulus decreases with an increase in wall defects. These findings are in reasonable agreement with those reported previously by Wang et al.

Hepatic omphalocele in an adult

The finding of an untreated omphalocele in adulthood is extremely rare. We report the case of a 29-year-old patient, who presented to us with a congenital defect of the abdominal wall and protrusion of underlying viscera.

Aneurysms in arterio-venous synthetic shunts after dialysis therapy. Morphology and pathogenesis

Synthetic grafts are used as arterio-venous fistulae (shunts) for dialysis therapy of patients with chronic renal insufficiency. Today grafts made of PTFE (polytetrafluorethylene) are commonly used. Grafts with diameter of 6 mm are implanted subcutaneously. In rare cases stenosis or thrombosis cause explantation of the grafts. Our results, obtained on 10 samples taken from surgery or autopsy, revealed that the main causes for graft explantation are destructions and perforations of the graft's wall caused by needle puncturing during dialysis. Single defects of the implants wall ranging from 200-500 micro m, and in some cases up to 1,5 mm are "repaired" by connective tissue. But greater defects cannot be compensated and are insufficiently covered by a network of loose connective tissue. These zones are under the predominated sites for development of false prosthetic aneurysm, which show parallel to posttraumatic aneurysms of vessels. Prosthetic aneurysms up to diameters of 3,2 cm were seen. Suitable choice of puncturing sites and puncturing technique can help to avoid destruction of the synthetic material.

Circumferential wrapping and clipping with temporalis fascia for treatment of unclippable intracranial aneurysms.

We utilized a clip-reinforced wrapping technique using temporalis fascia for treating unclippable aneurysms in 14 patients. Herein, we describe a modification of the clip- reinforced wrapping technique and report on the results. An appropriately sized strip of temporalis fascia is passed around the aneurysms with cuts made to accommodate perforating arteries. After applying fibrin glue, the aneurysm clip is positioned to secure the circumferential wrapping. Of the 14 patients, 4 (29%) were unclippable microbleb, 4 (29%) were wall defect, 3 (21%) were imperfect clipping due to the complexity of the aneurysm, 2 (14%) were bleb at the base of the aneurysm and 1 (7%) was a fusiform aneurysm. Multiple aneurysms were found in 6 (43%) patients and half (50%) of the 14 patients had MCA aneurysms. Postoperative angiography demonstrated no narrowing of parent arteries or enlargement of the aneurysms. No subsequent bleeding was observed during the 1 year follow-up period. These results suggest that circumferential wrapping-clipping with temporalis fascia and biological glue provides an alternative and safe method of treatment for unclippable intracranial aneurysms.

放射線照射, 腸骨部分切除, 皮膚移植後の腹壁瘢痕ヘルニア部に発生した皮膚浸潤を伴う盲腸癌切除後の腹壁欠損に対し, 大網充填が有効であった1例

放射線照射, 腸骨部分切除, 皮膚移植後の腹壁瘢痕ヘルニア部に発生した皮膚浸潤を伴う盲腸癌切除後の腹壁欠損に対し, 大網充填が有効であった1例

Plastic surgery of defects of the thoracic wall

Defects of the thoracic wall are mostly due to a malignant disease of the mammary gland. Radiotherapy is one of the essential methods of treating cancer of the breast in addition to primary surgery. If, after surgery, healing occurs by secondary intention or if there is a local recurrence or tumour formation in the thoracic wall due to irradiation, the body's reserves of soft parts are often exhausted and the adjacent tissue has been additionally damaged by the irradiation. General principles of treatment in the management of such problems are presented by means of several case reports.

Prenatal diagnosis of Cantrell's pentalogy with conventional and three-dimensional sonography

Omphaloceles and gastroschisis are the most common defects of the fetal anterior abdominal wall. The association of an omphalocele with an anterior thoracic wall defect could result from a variety of congenitalsyndromes of which Cantrell's pentalogy is the most common. For proper surgical scheduling of the neonate, early diagnosis of each of the components of this syndrome is important. The presence of a congenitalintracardiac anomaly is the best predictor of neonatal mortality. We present a case of Cantrell's pentalogy diagnosed prenatally with conventional and three-dimensional sonographic imaging, and confirmedat birth. We discuss this case and the reports in the world literature.

A free fibula autologous transfer for a full-thickness anterior chest wall defect

Large defects of the anterior chest wall lead to gross chest instability which can result in paradoxical respiration. Skeletal stabilization is an essential requirement in such cases. The current methods for achieving total or near total sternal reconstructions involve the use of alloplastic implant materials: prosthetic mesh with methyl methacrylate. In our experience, this method of reconstruction is often complicated by a persistent seroma and infection. A large full-thickness sternal defect was reconstructed by an osteotomized free fibula "Z" transfer and bilateral bipedicled pectoralis major myocutaneous flaps. This case highlights the use of vascularized autologous tissue for a complex full-thickness anterior chest wall reconstruction.

Using CT to diagnose tracheal rupture.

A retrospective study was performed to assess CT sensitivity for diagnosing tracheal rupture. Intubated cadaver tracheas were examined to assess endotracheal tube balloon overdistention and deformity and to evaluate the relationship of balloon pressures to tracheal injury. Neck or chest CT scans of 14 patients with tracheal rupture and 41 control trauma patients with pneumomediastinum but without tracheal injury were reviewed and compared to assess the presence and location of extrapulmonary air, whether direct visualization of tracheal wall disruption was possible, the size and shape of endotracheal tube balloon, signs of transtracheal balloon herniation in intubated patients, and the location of the extratracheal endotracheal tube. Intact and experimentally injured cadaver tracheas were used to evaluate tube balloon pressure and configuration. All 14 patients with tracheal rupture had deep cervical air and pneumomediastinum. Overdistention of the tube balloon occurred in 71% (5/7) of the intubated patients, and balloon herniation occurred in 29% (2/7). Direct tracheal injury was seen in 71% (10/14) of the patients as a wall defect (n = 8) or deformity (n = 2). Overall, CT was 85% sensitive for detecting tracheal injury. Patients with tracheal injury had a significantly lower incidence of pneumothorax (p = 0.01) than did the control group. The CT appearance of balloon herniation through defects in the cadaver tracheas closely mimicked those of patients with tracheal injury. The amount of balloon pressure required to rupture the intubated trachea was extremely high and rupture was difficult to obtain. CT can reveal tracheal injury and can be used to select trauma patients with pneumomediastinum for bronchoscopy, leading to early confirmation and treatment.

The use of a Gore-Tex soft-tissue patch to repair large full-thickness defects after subtotal sternectomy. A report of three cases.

Primary tumors of the sternum are rare, accounting for approximately 1% of primary bone tumors1. Most of these primary tumors are malignant, and the most common lesion is a chondrosarcoma. To avoid local recurrence, it is critical that a wide en bloc resection of the tumor be performed. Management of large defects of the chest wall after resection has ­remained difficult and controversial2. Various methods of reconstruction have been described, including the use of steel bars and Marlex mesh2, the use of Marlex mesh with or without methylmethacrylate3-7, and the use of acrylic resin4. When primary wound closure has not been possible, various myo­cutaneous flaps, including pedicle omental flaps, have been used to close the defect3,5,6,8-13. One of us (W.W.) and colleagues first used a Gore-Tex soft-tissue patch in 1992 to close a large chest-wall defect after a subtotal sternectomy that had been performed to remove a large benign chondromyxoid fibroma13. That report emphasized the unusual clinical and pathological findings of this rare benign tumor rather than the new operative technique. Since then, we have used Gore-Tex soft-tissue patches to reconstruct a large full-thickness defect of the anterior part of …

Grynfeltt's hernia

The aim of this study is to report a case and review the relevant literature. The patient was a 64-year-old male with a right lumbar mass of 5 × 6 cm, which protruded when abdominal pressure was increased. Surgery revealed a defect of 3 × 2 cm in the transversalis fascia in the superior lumbar triangle; prosthetic material was used in the preperitoneal space. Lumbar hernias are rare defects of the abdominal wall (2% of wall hernias); fewer than 300 cases have been reported in the literature. All lumbar hernias can be corrected with surgical treatment. A tension-free mesh repair is almost always necessary, and gives satisfactory results.

Interruption of gallbladder wall with pericholecystic fluid: a CT finding of perforation

In this report, we present an unusual case of gallbladder perforation due to acalculous cholecystitis, masked clinically by acute pancreatitis. Severe abdominal pain referred to the patient's back, nausea, vomiting, and high serum and urinary amylase values were compatible with acute pancreatitis. However, on contrast-enhanced CT, the size and appearance of the pancreas were normal while the gallbladder was abnormally enlarged with a wall defect indicating perforation, soon afterward confirmed by surgery.

Ropes of BN multi-walled nanotubes

Ropes consisting of tens of multi-walled boron nitride (BN) nanotubes and extending up to several μm were synthesized through a chemical reaction involving chemical-vapor-deposited multi-walled carbon (C) nanotube oxidation by B 2O 3 mixed with either MoO 3 or V 2O 5 in a flowing N 2 atmosphere. The ropes were analyzed by high-resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS). Tubular shells of BN in the ropes were preferentially assembled in a zigzag form with the [10 1 ̄ 0] direction parallel to the tube/rope axis. Oxidation-induced C nanotube opening at the tip and at wall defects, followed by substitution of C atoms with B and N atoms, and consecutive crystallization of BN shells on the seed nanotubes is thought to underlie the formation mechanism.

The port-decompression effect. A causative factor in the aetiology of post-laparoscopic port-site herniation?

Introduction Post-laparoscopic port-site herniation has been variously reported to have an incidence of up to 0.2%. In 86% of instances where port sizes of 10 mm or greater have been used, and lateral port sites are 35 times more at risk than suprapubic, with the umbilical locale being the most common site, associated with 75% of all hernias. Theory A port decompressing an abdomen insufflated to a pressure of 15 mmHg has a profound suction effect and can pick up a loop of bowel while being drawn out through the abdominal wall. We believe that, on occasion, this is the mechanism by which bowel can be drawn within the abdominal wall and rectus sheath defect, thereby contributing to port-site herniation. Methods We have obtained photographic evidence of bowel drawn up into a channel formed by a primary trocar. We demonstrate how bowel is caught by the suction effect of decompression through an open port and show that, despite the intraumbilical entry technique favoured by Garry, a channel can form through the abdominal wall which can trap bowel. We also examine the physics of gas flow and the relationship between port size, decompression technique and suction effect. Conclusion We suggest the abdomen should be decompressed slowly under direct vision, through the side tap, with the telescope remaining within the port. After gas release is completed, the primary port and telescope are removed together, with a clear view at all times that the port is free of any entrapped bowel.

Prevalence and mechanisms of small intestinal obstruction following laparoscopic abdominal surgery: a retrospective multicenter study. French Association for Surgical Research.

The prevalence and mechanisms of intestinal obstruction following laparoscopic abdominal surgery have not been studied extensively. Retrospective review of cases of intestinal obstruction after laparoscopic surgery. Sixteen surgical units performing laparoscopy in France. Twenty-four patients with intestinal obstruction. Prevalence values and descriptive data. The 3 most frequent primary procedures responsible for intestinal obstruction were cholecystectomy (10 cases), transperitoneal hernia repair (5 cases), and appendectomy (4 cases). Prevalences of early postoperative intestinal obstruction after these procedures were 0.11%, 2.5%, and 0.16%, respectively. Intestinal obstruction was due to adhesions or fibrotic bands in 12 cases and to intestinal incarceration in 11 cases. Obstruction was located at the trocar site in 13 cases (9 incarcerations and 4 adhesions), mainly at the umbilicus, and in the operative field in 10 cases (2 incarcerations in a wall defect after transperitoneal inguinal hernia repair, 4 adhesions, and 4 fibrotic bands). The small intestine was involved in 23 of 24 cases; the other was due to cecal volvulus following unrecognized intestinal malrotation. Intestinal obstruction was treated by laparoscopic adhesiolysis in 6 patients and by laparotomy in 18 patients, 6 of whom required small intestine resection. Three postoperative complications but no deaths occurred. Intestinal obstruction following laparoscopic abdominal surgery can occur irrespective of the type of operation; the prevalence is as high as (cholecystectomy and appendectomy) or even higher than (transperitoneal hernia repair) that seen in open procedures.

TWO CASES OF ABDOMINAL WALL RECONSTRUCTION USING TENSOR FASCIA LATA MUSCLE AND MUSCULOCUTANEOUS FLAPS AFTER RESECTION OF ABDOMINAL-WALL-INVADING MALIGNANT TUMORS

Today various kinds of musculocutaneus flaps have been introduced and used for defects after resection of malignant tumors which invade the abdominal wall. We experienced two cases of abdominal malignant tu-mor which invaded their abdominal wall, including a neuroendocrine carcinoma arisen from the transverse colon in case 1 and a mucinous adenocarcinoma right above the pubic bone in case 2. After the resection of the tumor, we used the tensor fascia lata (TFL) muscle and musculocutaneus flaps as muscle pedicle flaps. Though one patient of them died due to a rapid progression of the original malignant disease 3 months after the surgery, both patients had no trouble with their abdominal wall such as infection or hernia. So we think that the TEL flaps can be used safely and fairly easily to reconstruct the defect of the ab-dominal wall even for general surgeons. And the TFL flap method would be recommended for cases of ab-dominal reconstruction with a high risk of infection or with a probable retardation of cure.

Scaling of the turbulent boundary layer along a flat plate according to different turbulence models

Abstract At sufficiently large Reynolds number the turbulent boundary layer along a flat plate under zero pressure gradient can be split up in an inner and outer layer. The classical theory says that a law-of-the-wall holds in the inner layer, and a defect law in the outer layer. It is shown that four different types of commonly used turbulence models (an algebraic, k – ϵ , k – ω and a differential Reynolds-stress model) all reproduce the classical similarity scalings for Re θ above about 10 4 . This was verified by numerically solving the turbulent boundary-layer equations for Reynolds numbers (based on the momentum-loss thickness) in between 300 and 5×10 7 . The boundary-layer solution in the outer layer is shown to converge to the similarity solution of a defect-layer equation. All turbulence models considered give a wall function and defect law that is close to Direct Numerical Simulations of Spalart (1988) and new high-Reynolds-number experiments by Fernholz et al. (1995) . An exception is the algebraic model that gives a too thin boundary layer.

Tissue Response to Bone Substitute Materials Supporting Dental Implants

Abstract The purpose of this study was to evaluate the biological response of a bone substitute material placed around Ti dental implants surgically positioned in tooth extraction sites of canine mandible. Under general anesthesia six adult mongrel canine had bilateral extractions of the fourth premolarbicuspid. Each extraction site was modeled into a 4 wall defect with box-like dimensions (1.0 mm vertically x 1.2 mm horizontally x 0.75 mm laterally). Utilizing the Branemark technique, screwtype implants with healing screws (10 mm x 4 mm), were placed in the prepared sites. A synthetic hydroxyapatite bone cement (HAC) [BoneSource®, Howmedica Laboratories, Inc.] was prepared and filled in around each implant. As controls, three canine had HAC placed in prepared sites without implants. Prior to periodontal flap suture closure a n-butyl-2-cyanoacrylate biodegradable tissue adhesive [Histoacryl®], was placed over implants and HAC. One canine each was euthanized at one month (m), two m, and three m postop.

US findings of xanthogranulomatous cholecystitis

The ultrasound (US) scans of eleven patients with histologically proven xanthogranulomatous cholecystitis have been reviewed. The thickness of the gallbladder (GB) wall, echogenicity of the thickened GB wall, the presence of intramural nodules, gallstones, pericholecystic fluid, loss of wall definition with the liver, and intrahepatic ductal dilatation were specifically assessed by two radiologists. The range of thickness of the GB wall was 3-20mm (mean, 11.2 mm). Thickening was diffuse in nine cases and focal in two. The thickened GB wall, excluding intramural nodules, was echogenic in seven, isoechoic in three and hypoechoic in one, compared with hepatic echogenicity. Intramural nodules were found in eight cases. These were discrete, oval or flat, and of low echogenicity. These ranged in size from 6 to 12 mm (mean, 10.5 mm). Gallstones were present in six cases and there was intrahepatic duct dilatation in two of these. Definition between the liver and the GB was obliterated in seven cases. One case of GB perforation, confirmed at operation, demonstrated pre-operatively a GB wall defect and connection with the surrounding pericholecystic fluid. Pericholecystic fluid was absent in the other 10 cases. Xanthogranulomatous cholecystitis presents ultrasonically as GB wall thickening, and the majority of cases in this series also demonstrated intramural hypoechoic nodules. These findings can be helpful in the diagnosis of xanthogranulomatous cholecystitis.

Migration and wear of hydroxyapatite-coated press-fit cups in revision hip arthroplasty: A radiostereometric study

Screw-fixated and hydroxyapatite-coated press-fit cups were studied using radiostereometry in 29 revision and 14 primary arthroplasties. The acetabular defects in the revision cases varied from none to type 3 (wall defects) according to Gustilo—Pasternak. Morsellized allograft was used in 25 revisions. Nine of these cups rested on less than 50% living bone. After 2 years, the mean migration in the revised group reached 0.36, 0.21, and 0.49 mm in the horizontal, longitudinal, and anteroposterior (AP) directions. The mean rotations varied between 0.5° and 0.7° depending on direction. The primary implants displayed smaller mediolateral migration and AP tilt. The mean proximal wear rate for the whole group was 0.11 mm/y. A central gap on the postoperative AP view implied less migration. The size of the preoperative bone defects or amount of bone—graft used had no influence on the migration. Despite extensive use of morsellized allograft, this implant displayed the smallest migration so far reported in revision hip arthroplasty.