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At least 613 records · Page 34Linked to original sources
PubMed2003

Appositional bone formation in marginal defects at implants.

In a previous experiment, it was demonstrated that a wide marginal defect around an implant can heal with a high degree of osseointegration. The present experiment was performed to evaluate the degree and quality of de novo bone formation and osseointegration in marginal defects adjacent to submerged titanium implants. All mandibular premolars and 1st molars were extracted in four Labrador dogs. Four experimental sites were identified in the right side of the mandible. In two sites, custom-made implants with a sandblasted, large grit, acid-etched (SLA) surface were installed without further ostectomy (control sites). In the two remaining sites (test sites), a specially designed step drill was used to widen the marginal 5 mm of the canal. A barrier membrane was used to cover the implants in the defect sites. All implants were submerged. One month later, an identical procedure, including site preparation and implant installation, was performed in the left side of the mandible. Two months following the first implant installation procedure, biopsies were collected and prepared for sectioning. Ostectomy and implant installation in the control location resulted in a series of bone tissue alterations which eventually allowed newly formed bone to establish contact with the SLA surface. The marginal defect lateral to the implant in the test locations gradually became filled with newly formed bone. De novo bone formation started within the walls of the surgically prepared defect. Bone-to-implant contact was first established in the apical portion of the gap. This new bone tissue was in the coronal direction continuous with a dense, non-mineralized 'implant attached' soft tissue which, over time, also became mineralized to increase the height of the zone of bone-to-implant contact. The results suggest that healing of a wide marginal defect around an implant is characterized by appositional bone growth from the lateral and apical bone walls of the defect.

Acid Etching, Dental↗
PubMed2002

Use of collagen sponge incorporating transforming growth factor-beta1 to promote bone repair in skull defects in rabbits.

The objective of this study was to evaluate the potential of collagen sponge incorporating transforming growth factor-beta1 (TGF-beta1) to enhance bone repair. The collagen sponge was prepared by freeze-drying aqueous foamed collagen solution. Thermal cross-linking was performed in a vacuum at 140 degrees C for periods ranging from 1 to 48 h to prepare a number of fine collagen sponges. When collagen sponges incorporating 125I-labeled TGF-beta1 were placed in phosphate-buffered saline (PBS) solution at 37 degrees C, a small amount of TGF-beta1 was released for the first hour, but no further release was observed thereafter, irrespective of the amount of cross-linking time the sponges had received. Collagen sponges incorporating 125I-labeled TGF-beta1 or simply labeled with 125I were implanted into the skin on the backs of mice. The radioactivity of the 125I-labeled TGF-beta1 in the collagen sponges decreased with time; the amount of TGF-beta1 remaining dependent on the cross-linking time. The in vivo retention of TGF-beta1 was longer in those sponges that had been subjected to longer cross-linking times. The in vivo release profile of the TGF-beta1 was matched with the degradation profile of the sponges. Scanning electron microscopic observation revealed no difference in structure among sponges subjected to different cross-linking times. The TGF-beta1 immobilized in the sponges was probably released in vivo as a result of sponge biodegradation because TGF-beta1 release did not occur in in vitro conditions in which sponges did not degrade. We applied collagen sponges incorporating 0.1 microg of TGF-beta1 to skull defects in rabbits in stress-unloaded bone situations. Six weeks later, the skull defects were covered by newly formed bone, in marked contrast to the results obtained with a TGF-beta1 free empty collagen sponge and 0.1 microg of free TGF-beta1. We concluded that the collagen sponges were able to release biologically active TGF-beta1 and were a promising material for bone repair.

Animals↗
PubMed2006

A classification of the fibrin network structures formed from the hereditary dysfibrinogens.

OBJECTIVE: The main objective was to study the relationships of the molecular defects in 38 dysfibrinogens with their fibrin networks. METHODS AND RESULTS: Scanning electron microscopic analyses revealed that all the fibrins formed under the same conditions had networks composed of either normal thickness fibers or thin fibers, accompanied by a variety of alterations in the network structure and characteristics. We classified these fibrin networks into five classes, designated normal, less-ordered, porous A, porous B and lace-like networks. The dysfibrinogens with defects in fibrinopeptide A release or the E:D binding sites formed normal or less-ordered networks, while those with defects in the D:D association formed porous A networks composed of many tapered terminating fibers, despite having fibers of normal width, and containing many pores or spaces. The porous B and lace-like networks were composed of highly branched thin fibers because of defects in the lateral association among protofibrils, and the major difference between them was the porosity of the porous B networks. All the porous B networks were easily damaged by mechanical stress, whereas the lace-like networks retained high resistance to such stress, indicating that the network strength was not dependent on the fiber width, but on the porosity that led to fragility of the network. CONCLUSION: Impairment of the D:D association is the major disturbing factor that leads to the formation of porous fibrin networks. The porosity may be introduced by severe impairment of the D:D association, as well as the lateral association, as has often been observed by extra glycosylation or defects in Ca2+ binding.

Afibrinogenemia↗
PubMed2000

Cartilage repair by free periosteal grafts in the knees of pigs: a histologic study.

BACKGROUND AND PURPOSE: Periosteal grafts may result in cartilage formation and, therefore, have the potential to repair cartilage defects. We evaluated the histologic results of free periosteal grafts for the repair of full-thickness cartilage defects in pigs. METHODS: A free autogenous periosteal flap from the proximal tibia was grafted to a size-matched, full-thickness articular defect on the lateral femoral condyle of the knees of 12 pigs. The same defect on the medial femoral condyle was used as a control lesion. Biopsies were performed at 4, 8, and 12 weeks after grafting. RESULTS: The control lesions showed dense fibrous tissue with no evidence of cartilage-like tissues. The predominant tissues after grafting were mixtures of fibrous tissue, fibrocartilage, mesenchyme tissue, and occasional bone islands, but no cartilage tissue was identified. The tissue distribution did not change in the same knee from the week 4 to the week 8 biopsy; nonetheless, there were interindividual variations in tissue distribution. CONCLUSIONS: The results of this study do not support the use of free periosteal transplantation for full-thickness cartilage defects of the knee.

Animals↗
PubMed1975

Value and pitfalls of the lateral lung scan.

Two hundred eighty-one of 443 lung scans composed of anterior, posterior, and lateral projections (done in our hospital) demonstrated defects. In 3.9 percent of them (11 cases), the defects were delineated in the lateral views only, while in 29.2 percent (82 cases), the lateral views either outlined additional defects not appreciated on the straight views, or showed more extensive lung involvement. In the majority of instances, 56.6 percent (159 cases), the lateral views showed comparable findings and also tended to segmentally localize the defects better. However, in 10.3 percent (29 cases), defects present on the straight projections were not detected on the lateral views. Various causes that could give rise to artefactural abnormalities in the lateral lung scan and therefore inhibit its proper interpretation, are reviewed and discussed. Despite these problems, the lateral may be the only view to demonstrate abnormalities and, in fact, frequently provides additional useful information.

Humans↗
PubMed2006

[Effects of different durations of thromboembolism on blood gases, hemodynamics, pulmonary arteriography and thrombo-pathology in a canine model with selective embolization of pulmonary lobar arteries].

OBJECTIVE: To investigate the effects of different durations of thromboembolism on blood gases, hemodynamic parameters, pulmonary arteriography and thrombo-pathology in an animal model mimicking chronic pulmonary thromboembolism (PTE). METHODS: Sixteen dogs were embolized with five thrombi developed by autologous blood into the left lower pulmonary artery (n = 15) and the right lower pulmonary artery (n = 1, used to confirm the available method of selective embolization). The 15 dogs were divided into three groups: sham group (n = 5), one-week group (n = 5) and two-week group (n = 5) according to the different durations of embolization. Swan-Ganz catheter was used to guide a plastic duct, through which the thrombi were injected selectively into the left or right lower pulmonary artery by X-ray fluoroscopy. Local pulmonary arteriography of lower pulmonary arteries was taken. Blood pressure (BP), and blood gases were measured. Central venous pressure (CVP), mean pulmonary arterial pressure (MPAP), pulmonary arteriole wedge pressure (PAWP), and cardiac output (CO) were recorded, and pulmonary vascular resistance (PVR) was calculated. Each dog underwent muscular injection with tranexamic acid for one or two weeks to prevent thrombolysis. The lower lung lobe was dissected to confirm the thromboembolism after one or two weeks. The lung sections were stained with phosphotungstic acid hematoxylin (PTAH) to observe thromboemboli with optical microscopy. RESULTS: In the PTE group, PaO(2)/FiO(2), MPAP and PVR changed significantly as compared to baseline values (P < 0.05) after one hour of embolization, with MPAP increasing from (15 +/- 3) mm Hg to (21 +/- 4) mm Hg, PVR increasing from (178 +/- 114) mm Hg.s/L to (404 +/- 260) mm Hg.s/L, and PaO(2)/FiO(2) decreasing from (508 +/- 58) mm Hg to (395 +/- 100) mm Hg; these parameters returned to the baseline values one or two weeks later. After embolization, pulmonary arteriography demonstrated lower lobar artery cut-off perfusion defects. One week later, pulmonary arteriography demonstrated irregularities and stiffness of the arterial wall, enlarged proximal part of lower pulmonary artery and cut-off perfusion defects. Poor filling at embolus site was evident after embolization for two weeks. In the 1-week PTE group, organized tissue covered with the blue-purple fibrin nest was observed in the thrombus with PTAH stain. In the two-week group, the well organized thrombi were partially recanalized and surrounded and invaded by hyperplastic tissues from pulmonary artery wall. CONCLUSIONS: A canine model mimicking chronic PTE can be established by the use of fibrinolytic inhibitor tranexamic acid. Different manifestations on pulmonary arteriography and varied degree of organization of thrombi are evident at different times after embolization.

Angiography↗
PubMed2001

Recontruction of facial defects and burn scars using large size freehand full-thickness skin graft from lateral thoracic region.

Reconstruction of facial defects due to trauma, burn scar and congenital deformities is very challenging for reconstructive surgeons. Although many alternative techniques have been suggested, the ideal technique has not been described yet. Full-thickness skin grafting procedures are one of the options, but when larger grafts are needed, donor site morbidity is problematic. Full-thickness skin graft harvested from lateral thoracic region has some advantages for face reconstruction with its larger size, similar colour, thickness, skin quality and texture.

Burns↗
PubMed1997

Lateral arm microvascular flap in head and neck reconstruction.

OBJECTIVES: To report our results of a study of 28 patients who underwent sequential reconstructions of the head and neck using the lateral arm flap. To discuss the situations where we have found the procedure useful, report the complication rates, and delineate the advantages and disadvantages of using this flap. DESIGN: A clinical series of patients was followed up prospectively. The swallowing function of a subgroup that underwent oropharyngeal reconstruction was compared with that of a simultaneous control group that underwent reconstruction with the pectoralis major flap. SETTING: University medical center. PARTICIPANTS: Patients with malignant neoplasms of the head and neck who underwent resections and reconstruction with the lateral arm flap. INTERVENTIONS: Twenty-eight patients underwent head and neck reconstruction using lateral arm flaps. In 17 patients, the lateral arm flaps were used for pharyngeal and posterior oral cavity defects. Thirteen of these patients underwent reinnervation. Nine combined palatal and midfacial defects were reconstructed, and 1 lateral facial defect was reconstructed. Most cases were advanced malignant neoplasms and represented a selected minority of similar resections performed at our institutions. Three maxillary reconstructions were performed secondarily. All other reconstructions were performed at the time of tumor ablation. MAIN OUTCOME MEASURES: Data were collected regarding flap survival, return of sensation in flaps, complication rates, and the ability to feed orally. RESULTS: All flaps survived in their entirety. Of 7.5 tested flaps acquired sensation. Of 14 patients with large oropharyngeal defects, 8 resumed early oral feeding and all survivors eventually obtained nutrition orally. The ability to swallow was superior to the results obtained in a retrospective analysis of a group reconstructed using pectoralis major flaps. CONCLUSIONS: A unique feature of this flap is that it incorporates both thin skin from the proximal forearm and thicker skin from the upper arm. This is ideal for an oropharyngeal defect, where the thin malleable portion can be used in the posterior oral cavity or pharyngeal wall and the thicker portion in the tongue base. Either portion can be used alone as well. The availability of intermediate tissue bulk can also be advantageous for midfacial reconstruction. Sensation can be reliably reconstituted with this flap. We think that the lateral arm flap is versatile and has particularly low donor-site morbidity.

Adult↗
PubMedDate not supplied

[A reliable symptom in differential diagnosis of cochlear and retrocochlear neurosensory hypoacusis (study of sound lateralization in Weber's test and ultrasound)].

Sound laterality in Weber test occurs mainly in peripheral defects of the acoustic analyzer (lateral conduction or reception acoustic defects of the cochlea). In retrocochlear unilateral hypoacusis or loss of hearing, laterality in this test is absent in 80-90% of the cases (affection of the VIII nerve root, acoustic nuclei, stem and midbrain conductors). This symptom is most reliable in differentiation of cochlear with retrocochlear unilateral hypoacusis and deafness. In combination of retrocochlear hypoacusis of deafness with impaired sound conduction in the same ear, the sound in Weber test can show a paradoxical laterality in an absolutely deaf ear. This indicates that Weber test sound laterality definitely reflects changes in sound conduction. Ultrasound laterality occurs in the better hearing ear in any unilateral cochlear or retrocochlear lesions, thus complicating recognition of cochlear from retrocochlear affections. Laterality of ultrasound is a sensitive indicator of neurosensory abnormalities. Major trepanation bone defects of the parietotemporal skull did not influence sound laterality in Weber test.

Cochlea↗
PubMed2004

Presenting phenotype in 100 children with the 22q11 deletion syndrome.

UNLABELLED: The aim of this study was to investigate and describe the presenting phenotype of children with the 22q11 deletion syndrome and to describe common clinical features that could serve as guidelines in the clinical diagnostic process preceding genetic testing. A hospital-based study of 100 consecutive children and adolescents with 22q11 deletion was initiated. The patients were divided into two groups according to age at diagnosis: before or after 2 years of age. Clinical features were grouped into a core set of eight features: cardiac defects, non-visible/hypoplastic thymus or infection problems, hypocalcaemia, feeding difficulties, cleft palate/speech-language impairment, developmental delay/learning difficulties, characteristic dysmorphic features and other malformations and deformities. The median age at diagnosis was 6.7 years. Of all patients, 26% were diagnosed in infancy and 92% had a congenital cardiac defect, whereas 54% of those diagnosed later had a cardiac defect. A cleft palate was present in 25 cases and 44 had some other malformation or deformity. All presented with a combination of many of the core features. Of those diagnosed after 2 years of age, the majority presented with speech-language impairment, developmental delay or learning difficulties and recurrent infections. Characteristic mild dysmorphic features were noticed in all children. CONCLUSION: In spite of variable clinical expression, children with 22q11 deletion share a number of major features and have a characteristic phenotype. A high proportion have no cardiac defect and hence a risk of diagnostic delay. Increased awareness and knowledge among general paediatricians and other specialists who meet these children early in life is needed to reduce the diagnostic delay.

Abnormalities, Multiple↗
PubMed1995

Local and remote matrix responses to chondrocyte-laden collagen scaffold implantation in extensive articular cartilage defects.

Chondrocyte-laden collagen scaffolds were evaluated in extensive cartilage defects in an equine model. Arthroscopic techniques were used to implant a chondrocyte-collagen culture product in 15-mm defects in the lateral trochlear ridge of the femoropatellar joint of 12 horses. Ungrafted control defects were formed in the opposite joint. Groups of six horses were terminated at 4 and 8 months after implantation and the repair sites, adjacent cartilage, and remote cartilage within each femoropatellar joint examined biochemically. Eight months following surgery the relative proportions of type II collagen in grafted and ungrafted defects, determined using the ratio of cyanogen bromide cleavage products alpha 1(II)CB10/alpha 2(I)CB3,5, were not significantly different (31.57 +/- 2.76% and 26.88 +/- 2.76%, respectively). Aggrecan content was significantly improved in grafted defects (85.61 +/- 6.51 and 74.91 +/- 10.31 micrograms/mg dry weight). Cartilage surrounding grafted defects also showed improved maintenance of cartilage glycosaminoglycan content. Thus, chondrocyte grafting in collagen scaffold vehicles improved the aggrecan content in extensive cartilage defects and surrounding normal cartilage. However, given the continued disparity between repair tissue and normal cartilage aggrecan content, and the low proportion of type II collagen in grafted defects, the utility of collagen scaffolds for chondrocyte grafting of large cartilage defects seems limited.

Animals↗
PubMed1999

Reconstruction of the mandible with osseous free flaps: a 10-year experience with 150 consecutive patients.

Osseous free flaps have become the preferred method for reconstructing segmental mandibular defects. Of 457 head and neck free flaps, 150 osseous mandible reconstructions were performed over a 10-year period. This experience was retrospectively reviewed to establish an approach to osseous free flap mandible reconstruction. There were 94 male and 56 female patients (mean age, 50 years; range 3 to 79 years); 43 percent had hemimandibular defects, and the rest had central, lateral, or a combination defect. Donor sites included the fibula (90 percent), radius (4 percent), scapula (4 percent), and ilium (2 percent). Rigid fixation (up to five osteotomy sites) was used in 98 percent of patients. Aesthetic and functional results were evaluated a minimum of 6 months postoperatively. The free flap success rate was 100 percent, and bony union was achieved in 97 percent of the osteotomy sites. Osseointegrated dental implants were placed in 20 patients. A return to an unrestricted diet was achieved in 45 percent of patients; 45 percent returned to a soft diet, and 5 percent were on a liquid diet. Five percent of patients required enteral feeding to maintain weight. Speech was assessed as normal (36 percent), near normal (27 percent), intelligible (28 percent), or unintelligible (9 percent). Aesthetic outcome was judged as excellent (32 percent), good (27 percent), fair (27 percent), or poor (14 percent). This study demonstrates a very high success rate, with good-to-excellent functional and aesthetic results using osseous free flaps for primary mandible reconstruction. The fibula donor site should be the first choice for most cases, particularly those with anterior or large bony defects requiring multiple osteotomies. Use of alternative donor sites (i.e., radius and scapula) is best reserved for cases with large soft-tissue and minimal bone requirements. The ilium is recommended only when other options are unavailable. Thoughtful flap selection and design should supplant the need for multiple, simultaneous free flaps and vein grafting in most cases.

Adolescent↗
PubMed1988

Relationships between laterality of congenital upper limb reduction defects and school performance.

Eighty children (34 males, 46 females) with congenital upper limb reduction defects who attended a regional amputee clinic between 1956 and 1986 were classified as to whether they exhibited learning difficulties in school, as indicated by grade failure or by placement in learning disability classrooms. Children with right-sided defects were more likely to encounter learning difficulties than were children with left-sided defects (Chi-square = 6.8; df = 1; p less than 0.01). Children with right-limb defects also were more likely than children with left-limb defects to experience reading problems (Chi-square = 5.9; df = 1; p less than 0.05). These results suggest the need for neuropsychological and neurophysiological study of children with limb reduction defects.

Arm↗