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At least 505 records · Page 28Linked to original sources
PubMed2004

Influence of biosurfactants from probiotic bacteria on formation of biofilms on voice prostheses.

Biofilms were grown on preconditioned voice prostheses with biosurfactants obtained from probiotic bacteria Lactococcus lactis 53 and Streptococcus thermophilus A in an artificial throat model. Both biosurfactants greatly reduced microbial numbers on prostheses and also induced a decrease in the airflow resistance that occurs on voice prostheses after biofilm formation. This study presents a promising strategy for prolonging the lifespan of voice prostheses.

Biofilms↗
PubMed2006

Effects of quaternary ammonium silane coatings on mixed fungal and bacterial biofilms on tracheoesophageal shunt prostheses.

Two quaternary ammonium silanes (QAS) were used to coat silicone rubber tracheoesophageal shunt prostheses, yielding a positively charged surface. One QAS coating [(trimethoxysilyl)-propyldimethyloctadecylammonium chloride] was applied through chemical bonding, while the other coating, Biocidal ZF, was sprayed onto the silicone rubber surface. The sprayed coating lost its stability within an hour, while the chemically bonded coating appeared stable. Upon incubation in an artificial throat model, allowing simultaneous adhesion and growth of yeast and bacteria, all coated prostheses showed significant reductions in the numbers of viable yeast (to 12% to 16%) and bacteria (to 27% to 36%) compared with those for silicone rubber controls, as confirmed using confocal laser scanning microscopy after live/dead staining of the biofilms. In situ hybridization with fluorescently labeled oligonucleotide probes showed that yeasts expressed hyphae on the untreated and Biocidal ZF-coated prostheses but not on the QAS-coated prostheses. Whether this is a result of the positive QAS coating or is due to the reduced number of bacteria is currently unknown. In summary, this is the first report on the inhibitory effects of positively charged coatings on the viability of yeasts and bacteria in mixed biofilms. Although the study initially aimed at reducing voice prosthetic biofilms, its relevance extends to all biomedical and environmental surfaces where mixed biofilms develop and present a problem.

Anti-Bacterial Agents↗
PubMed1978

Experience with Silastic prostheses in the rheumatoid hand. A 5-year follow-up.

Nine patients with rheumatoid arthritis, who had Silastic prostheses (Swanson's) introduced into 34 metacarpophalangeal joints, were reviewed 5 years after surgery. The most important long-term advantage conferred by the introduction of prostheses was pain relief; functional benefit was marginal. The majority of prostheses eventually fractured but this did not necessarily lead to a functional deterioration. Impairment of function was usually the result of loss of flexion at the metacarpophalangeal joints, but it was sometimes due to excessive instability after fracture of the prostheses. It is suggested that Silastic joint replacement may be a worthwhile procedure in rheumatoid patients with moderate destruction or deformity of the metacarpophalangeal joints when pain is a predominant feature. Significant functional improvement can be anticipated only when secondary to pain relief.

Adult↗
PubMed1988

Bone-ingrowth hip prostheses in asymptomatic patients: radiographic features.

The radiographic changes of 85 bone-ingrowth femoral prostheses in 77 asymptomatic patients were reviewed. The average postoperative follow-up time was 21.8 months. In decreasing order of frequency, the alterations included (a) remodeling of the proximal medial edge of the cut femoral neck (stress shielding) (98%), (b) linear lucency with a thin sclerotic margin at the prosthesis-bone interface (that may increase in width or length with time) (79%), (c) endosteal sclerosis at the prosthesis tip (36%), (d) heterotopic bone (24%), (e) cortical thickening at the tip of the prosthesis (12%), (f) prosthetic subsidence (7%), (g) intraoperative fracture (7%), and (h) periosteal reaction (4%). In this study, radiographic evidence of these findings was not associated with clinical failure. This is in distinction to the findings in cemented prostheses, in which many of these phenomena (especially the development of increasing width of the lucent line adjacent to the cement or prosthesis) have been associated with failure. Long-term investigations of porous-coated prostheses are necessary. Currently, however, an awareness of the radiographic alterations that occur with asymptomatic bone-ingrowth prostheses can prevent their misinterpretation as abnormal.

Female↗
PubMed1980

Influence of porosity on the viability of the neointima. A histological investigation on implanted synthetic vascular prostheses.

The influence of porosity on the viability of the neointima was evaluated in two types of Dacron vascular prostheses with quite different porosities. It could be concluded that the observed parietal thrombus formation in functioning prostheses, and the dislodgement of the neointima in several of these, might well be attributed to the low porosity of the investigated prostheses, as compared to the recommended value. At the same time it is remarkable that no pronounced difference in the histological picture was observed in the two types of prostheses, despite large differences in their mutual porosities.

Animals↗
PubMed1983

Comparison of two voice prostheses for vocal restoration following laryngectomy.

Two prostheses for voice rehabilitation after laryngectomy were compared. A comparison was also made to evaluate the interchangeability of the two prostheses (Panje button and Blom-Singer duckbill) when only a single tracheoesophageal fistula was made. Fourteen laryngectomized patients were included in the study. Factors taken into account were voice quality, intelligibility, surgical technique, ease of insertion of the prostheses, patient preference, and care of each device. It was concluded that the Panje button in a Blom-Singer fistula offered better results when voice quality was compared. Patient selectivity is a factor important to the high success rate reported for voice restoration when either prosthesis is used. The development and success of these new prostheses is highlighted in a brief review of the literature.

Consumer Behavior↗
PubMed1994

Imaging of ossicular prostheses.

The prostheses available for reconstruction of the ossicular chain have expanded to include a variety of synthetic materials. Hydroxyapatite contains the inorganic constituents found in human living bone and is currently being incorporated into many new prostheses. This study demonstrates the computed tomography and magnetic resonance image characteristics of eight middle ear prostheses, a block of dense hydroxyapatite, and a human incus. Imaging of ossicular prostheses is more informative with computed tomography.

Bone Substitutes↗
PubMed1988

Small-calibre vascular grafting into the rat abdominal aorta with biodegradable prostheses.

130 Male Wistar rats, 2-3 months old and weighing 250-350 g were operated on to implant biodegradable small-calibre vascular prostheses (length 10 mm; internal diameter 1.5 mm) in their infrarenal abdominal aorta. The mean operation time was 40 min, the mean aortic cross-clamping time 25 min. The early patency rate was 100%, the late patency rate was 97.7%, and the operative mortality was 3.1%. Microscopical examination of the biodegradable prostheses from 1 h up to 1 year after implantation demonstrated reproducible morphological results; in these prostheses a new arterial wall regenerated which had a structure very similar to the normal arterial wall. It was concluded that the rat is an appropriate experimental laboratory animal for testing new types of small-calibre vascular prostheses.

Animals↗
PubMed2005

Trends in indirect dentistry: 7. Communicating design features for fixed and removable prostheses.

UNLABELLED: Clear and effective communication of design features between dental practitioners and dental technicians has long been recognized as central to the production of high quality fixed and removable prostheses. In this respect, there is extensive evidence to demonstrate that the quality of communication achieved from general dental practice is not always adequate. Failure to communicate design features effectively can lead to errors in the fabrication of prostheses, or in the production of prostheses with a potential to cause damage to oral structures. CLINICAL RELEVANCE: The aim of this paper is to describe why it is important to communicate adequate design features clearly to dental laboratories.The paper also describes how this may be achieved for a variety of fixed and removable prostheses.

Adult↗
PubMed1978

Mechanical tests on the tibial components of non-hinged knee prostheses.

Cadaveric knees replaced with the Geomedic, ICLH, Marmor and Total Condylar prostheses were tested in axial compression, in rotation and in hyperextension in order to observe the strength of fixation of the tibial components. In axial compression the strengths at failure varied widely, both with any one prosthesis and between prostheses. This is attributed largely to the strength of the cancellous bone of the tibia, which was measured in each case and also varied widely. Three natural knees failed at loads of 7300, 7600 and 8300 newtons respectively, whereas the strengths of replaced knees ranged from 3000 to 15750 newtons. At least one example of each design failed at less than 7300 newtons, suggesting little or no reserve of strength. The strength of fixation was greater when the tibial prosthesis was large enough to rest on the whole cross-section of the tibia. In rotation the three prostheses embodying rollers in troughs were stiffer than the Marmor which had a nearly flat tibial-bearing surface. The presence or absence of the cruciate ligaments had a negligible effect on torsional stiffness. In hyperextension, knees replaced with the ICLH, Marmor and Total Condylar prostheses failed by rupture of the posterior capsule at moments of about 60 newton-metres, compared with about 100 for natural knees. With the Marmor prosthesis the anterior cruciate ligament was avulsed at about 20 newton-metres compared with about 75 in natural knees, suggesting that in this respect the retention of the cruciate ligaments contributes little. None of the four knees tested after inserting a Geomedic prosthesis showed strengths as high as those replaced with the other three designs.

Humans↗
PubMed1993

Tibial high-density polyethylene wear in conforming tibiofemoral prostheses.

We have studied 27 tibial prostheses retrieved from knee replacements after 1 to 9 years. In 22 the femoral components were of cobalt-chrome, in five polyacetal. The design of the components gave a nominal contact area of 320 mm2 on each condyle. The tibial component was of high-density polyethylene (HDP) at least 6 mm thick, and not heat-treated. In the metal/HDP prostheses the average wear rate was 0.025 mm/year. The relative wear on the medial and lateral sides was related to the leg axis. None of the retrieved prostheses showed any severe disruption of their surface. The polyacetal/HDP prostheses showed similar wear with a statistically insignificant trend towards slower penetration. We conclude that the rate of wear of HDP in a conforming tibiofemoral bearing with a fixed tibial component at least 6 mm thick and not heat-treated is slow enough to be safe in clinical practice.

Acetals↗
PubMed1983

Anatomic and clinical analysis of 96 Beall prostheses explanted over a 13-year period.

Over 13 years, 96 Beall prostheses (80 Teflon, 16 Pyrolite) explanted at surgery were examined for durability, material wear, and clinical symptoms leading to surgical indication for excision were evaluated. The Teflon valves showed progressive disc wear and notching and two cases of disc escape from the cage; the Pyrolite discs were intact in all prostheses. The Dacron-Velour covering common to both types showed dehiscence at the inlet, significantly more severe after the third implant year in the Teflon (p less than 0.005) than in the Pyrolite prostheses. Sixty-nine (85 percent) cases with Teflon valves showed clinical manifestations of congestive heart failure due to prosthetic dysfunction; in 50 there was significant hemolytic anemia. Seven (44 percent) of the 16 Pyrolite disc valves were excised primarily because of dysfunction. The degree of hemolysis with the Pyrolite valves was usually mild. These data clearly suggested the advisability of early excision of the Beall Teflon prostheses in symptomatic patients and a close follow-up in patients with the Pyrolite models.

Adult↗
PubMed2002

[Expanding control possibilities of myoelectric hand prostheses].

Raising control possibilities of myoelectric prostheses--The control of hand prostheses is based on the surface scan of myoelectric voltage caused by muscle contractions in an amputees arm stump. So far available prostheses only perform up to two different grip types. This paper introduces a control scheme that is able to execute a variety of grip types dependent on the patient's control signals. Therefore a platform is presented to adapt control parameters especially to the patients anatomy. Developed algorithms are flashed on a microcontroller, processing data online and controlling a new generation of prostheses (FZK-prosthesis, Forschungszentrum Karlsruhe).

Amputation Stumps↗
PubMed1988

Speech rehabilitation in laryngectomees with tracheo-oesophageal fistulas and prostheses.

The Staffieri technique was used in 24 patients, but abandoned due to aspiration. The Blom-Singer or other prostheses were used in 40 cases, 50% achieved fluent speech, 15% spoke partially and 35% were not able to use the prostheses at all. Some complications are always met with in these cases: Dysphagia, leakage around the prostheses and difficulties with the function of the prostheses. The selection of suitable cases is important. Their cooperation and motivation must be ensured preoperatively, and in many cases like those living under poor social conditions or in older patients, this procedure should not be tried.

Humans↗
PubMed1978

Control of upper-limb prostheses: a case for neuroelectric control.

A discussion is presented on the control aspects of upper-limb prostheses, with emphasis on the areas of necessary improvements in current designs. Arguments are presented to indicate that it should be possible to obtain a substantial improvement in prostheses control by properly training the amputee, improving the dynamics response of the prostheses, and improving the quality of the forward-path control signal. Augmentation of feedback information, although useful, may not be essential. The limitations of the myoelectric (muscle) signal as a forward-path control signal, especially for multiple degrees-of-freedom prostheses, is discussed. Most of the limitations of the myoelectric signal can be overcome if the neuroelectric (nerve) signal is used as a forward-path control signal. Results of a series of experiments which demonstrate the feasibility of constructing an electrode capable of being implanted around severed nerves and of detecting neuroelectric signals for prolonged periods of time are presented. A possible scheme for employing neuroelectric control is also presented.

Arm↗
PubMedDate not supplied

Sealing of highly porous fabric vascular prostheses by adipose connective tissue fragments instead of preclotting with fresh blood.

Preclotting is an essential procedure for porous fabric vascular prostheses, but fatal bleeding due to fibrinolysis after implantation can occur in some cases. To overcome this problem, a method was developed to seal highly porous fabric vascular prostheses with adipose connective tissue fragments. A piece of subcutaneous adipose connective tissue weighing approximately 1 g was minced with scissors and stirred into 20 mL of saline, thereby creating a tissue suspension. This was sieved through the wall of a highly porous fabric prosthesis from the outside to the inside by intraluminal suction. The prostheses were implanted in the thoracic descending aortae of 20 dogs and removed from 1 h to 1 year after implantation. Twelve preclotted prostheses were used as controls. None of the the treated grafts experienced bleeding complications postoperatively. In the controls, the chest wall was closed after the bleeding stopped from the suture line and through the prosthesis wall, but problems occurred after surgery. Three out of 12 control animals (25%) bled in the pleural cavity within 24 h. In the tissue-sealed grafts, smooth neointima formation without any degenerative changes was observed during a 1-year observation period.

Adipose Tissue↗
PubMed1994

Extracellular matrix metalloproteinases around loose total hip prostheses.

We have explored the tissue localization of extracellular matrix metalloproteinases MMP-1 (fibroblast collagenase), MMP-2 (72-kDa gelatinase/Type IV collagenase), MMP-3 (stromelysin), MMP-8 (polymorphonuclear leukocyte collagenase) and MMP-9 (92-kDa gelatinase/Type IV collagenase) in the tissues around loose hip prostheses. The findings were compared with those in synovial tissues obtained from patients with a fractured femoral neck. MMP-type specific antisera were applied in the sensitive avidin-biotin-peroxidase complex methods. MMP-1 was found in monocyte/macrophages, fibroblasts, and vascular endothelial cells in both interface tissues between bone and acetabular components and the pseudocapsular tissues obtained from loosening of hip prostheses. In these tissues, MMP-8 was occasionally found, but only in polymorphonuclear leukocytes. Cells showing immunoreactivity to 72- and 92-kDa gelatinase/Type IV collagenase, MMP-2 and MMP-9, respectively, and stromelysin, MMP-3, were abundant in both interface and pseudocapsular tissues in loose hip prostheses. In contrast, in hip fractures, immunoreactivity to MMP-1, 2, 3, and 9 was weak and only observed in synovial tissues. Immunoreactivity to MMP-8 was confined to polymorphonuclear leukocytes attached to the synovial membrane or in the infiltrate around blood vessels in the subsynovial connective tissues. The finding of MMP-1, 2, 3, and 9 in the tissues around loose hip prostheses suggests that they play a role in the weakening of connective tissues, and this leads to loosening.

Aged↗
PubMed2004

[Induction of differentiation of CD34+ cells in vitro and application in endothelialization of blood vessel prostheses].

OBJECTIVE: To induce differentiation of CD(34)+ cells from varying sources into epithelial cells for potential application of blood vessel prostheses. METHODS: CD(34)+ cells were isolated from canine peripheral blood and bone marrow or human umbilical cord blood by an immune magnetic cell sorting system. The isolated CD(34)+ cells were induced to differentiate into endothelial cells in a liquid culture with VEGF. Endothelial cells were evaluated by immunocytochemistry and transmission electron microscopy. CD(34)+ cells were seeded on PTFE prostheses, which were harvested and observed by electron microscopy. RESULTS: The average isolated CD(34)+ cells from peripheral blood, bone marrow and umbilical cord blood were (26.30+/-2.42)%,(41.84 +/-3.65)%and (74.62+/-4.46)%, respectively. The number of CD(34)+ cells increased with the culture duration and reached to the highest level at the 14th d. Immunostaining showed positive signal for CD31 in endothelial cells and positive for factor VIII in cell culture. Transmission electron microscopy found Weibel-Palade bodies in the cytoplasm. Scanning electron microscopy demonstrated a single- layer of flat cells in the innermost layer of PTFE prostheses, and the cells were not of tropism. CONCLUSION: CD(34)+ cells isolated from peripheral blood, bone marrow and umbilical cord blood can be induced into endothelial cells; bone marrow and umbilical cord blood can be used as the sources of seeding cells for endothelialization of prostheses.

Antigens, CD34↗