The effect of buttermilk consumption on biofilm formation on silicone rubber voice prostheses in an artificial throat

Biofilm formation on indwelling silicone rubber voice prostheses in laryngectomized patients is still the main reason for dysfunction of the valve, leading to frequent replacements. Within patient support groups in The Netherlands, laryngectomees have suggested that the consumption of buttermilk prolongs the life-time of indwelling silicone rubber voice prostheses. The aim of the present study was to compare biofilm formation on Groningen button voice prostheses in a so-called artificial throat. Ten prostheses were placed in a simulated control group and ten other prostheses in a group with a simulated consumption of 700 ml buttermilk three times a day. Biofilms were allowed to grow on the prostheses by inoculating two artificial throats with the total cultivable microflora (bacteria and yeasts) isolated from an explanted Groningen button voice prosthesis. After 3 days, one artificial throat was perfused three times daily with phosphate buffer (control group) for 8 days, while the other artificial throat was perfused with buttermilk. Prostheses removed from the artificial throat in the control group were covered with a thick biofilm. Scanning electron microscopy showed microcolonies growing into the silicone rubber, similar to the ingrowth observed on explanted Groningen buttons. The simulated consumption of buttermilk in the other artificial throat almost fully prevented the formation of a biofilm on the prostheses during the experimental period. These in vitro experiments in the artificial throat demonstrate that the deterioration of voice prostheses can be lessened by the daily intake of buttermilk through its inhibitory effects on biofilm formation.     

A new method for in vivo evaluation of biofilms on surface-modified silicone rubber voice prostheses

A new method is presented that permits a rapid and accurate in vivo evaluation of biofilm formation on surface-modified silicone rubber voice prostheses. The method is based on partial modification of a Groningen button voice prosthesis by exposing half of the prosthesis to an argon plasma. This results in one side of the prosthesis becoming hydrophilic while leaving the unmodified side hydrophobic as a control. Modified prostheses were placed in patients for an evaluation period of approximately 4 weeks. Despite making the silicone rubber surface hydrophilic, biofilm formation was stimulated when compared to unmodified, hydrophobic silicone rubber. Findings show that biofilm formation on voice prostheses is influenced by hydrophobicity of a silicone rubber surface. The method of partial surface modification used was seen to be suitable for demonstrating such influences regardless of nutrition and other variations in the patient's lifestyle. Microbiological analysis of the biofilms on both sides of the prosthesis valve did not show any changes in microbial composition, with Candida albicans, streptococci and staphylococci being the most commonly isolated strains.     

Voice prostheses with sound-producing metal reed element--an experimental study and initial clinical results

BACKGROUND: Following total laryngectomy the voice is produced by esophageal speech as well as with voice prostheses by vibrations of pharyngeal mucosal folds. This pharyngeal sound normally has a significantly lower fundamental frequency than the healthy voice (men about 120 Hz, women about 240 Hz, pharyngeal voice about 70 Hz), which is a handicap especially for female laryngectomy patients. In order to improve the postlaryngectomy voice, a new type of voice prostheses containing an integrated sound-producing metallic reed element was developed (ADEVA Company, Lübeck, Germany). METHODS/PATIENTS: Thirty-five of these new sound-producing voice prostheses were tested in vitro for different prosthesis-specific physical parameters (pressure, flow, sound pressure, flow resistance, frequency range). In 15 voice prosthesis speakers, a sound-producing prosthesis was introduced during a routine outpatient visit. Besides measurement of the above mentioned physical parameters in patients with conventional and sound-producing prostheses, the resulting voice as also evaluated by means of a video recording. RESULTS: In vitro all prostheses with the metallic reed element produced a clear sound. Flow resistance of the prostheses was slightly elevated by the reed element. Insertion of the prostheses was hindered by the reed element. Period of uninterrupted sound production was prolonged after insertion of a sound-producing prosthesis and patients could speak on a lower pressure level, but the sound of the reed element was permanently distinguishable only in 6 of 15 patients. CONCLUSIONS: In principle a variation of the pharyngeal voice by means of a sound producing element, which is integrated into a voice prosthesis, is possible. The current design of the metallic reed element tested is not yet suitable for routine clinical use: 1. The reed element is too sensitive and is easily damaged during insertion, so the insertion device has to be improved. 2. The sound producing element is blocked by small amounts of tracheal secretions, so that this element should be replaceable separately without requiring removal of the silicone value (if possible by the patient himself). Prior to insertion of the sound producing voice prosthesis the maximum air flow through the shunt should be measured to determine if the patient can produce the necessary air flow for activation of the reed element. A further improvement for these special types of voice prostheses would be a sound producing element, which generates a variable frequency of sound. Limiting the patient to only one fundamental frequency creates a monotone, which does not sound naturally. Initial progress toward a sound-producing voice prostheses has been made. This should be followed by the necessary improvements in order to improve the feasibility of this design for routine clinical use.     

Antibacterial activity of antibiotic coated silicone grafts

PURPOSE: Postoperative infection remains one of the most serious complications of implantation of penile prostheses. Attempts to reduce the rate of infection by spraying the prosthesis with an antibiotic solution prior to implantation, along with perioperative antibiotics, have failed to eradicate infection. No published studies have evaluated the effect of antibiotic coating of penile prostheses. In this study, we evaluate the antibacterial effect of antibiotic-coated silicone strips as a surrogate for the penile prosthesis. MATERIALS AND METHODS: Strips coated with several different antibiotics were dipped in bacterial solutions containing Staphylococcus epidermidis or S. aureus and implanted subcutaneously in adult Sprague-Dawley rats. After a week, the strips were removed, and the number of bacteria on the strips and in the surrounding tissue were determined. The in vitro antibiotic activity of the antibiotic-coated strips against the same organisms was also determined. RESULTS: In the group of rats that received silicone strips contaminated in vitro with S. epidermidis, six of nine control rats yielded strips and tissues containing heavy bacterial growth. None of six strips coated with rifampin/minocycline yielded bacterial growth, nor did any of the seven strips coated with vancomycin. One of seven rats that received amikacin-coated strips had infection of the strip. The tissue results were similar to the strip results. In the group using S. aureus as the contaminating bacterium, the strips and tissues from eight of nine control rats yielded bacteria. None of the six rifampin/minocycline-coated strips yielded bacteria, while two of seven vancomycin-treated strips and two of six amikacin-coated strips were infected with S. aureus. The difference in bacterial growth between controls and antibiotic-coated strips reached a level of statistical significance for the rifampin/minocycline and vancomycin groups and was highly significant for the rifampin/minocycline groups. CONCLUSION: The experimental results presented here suggest that coating silicone graft material with antibiotics, particularly rifampin/minocycline, can reduce the incidence of graft colonization in contaminated wounds in rats, even in the absence of systemic antibiotics. These graft materials may prove useful in preventing the infection of penile prostheses.     

Prospective randomized comparative study of tracheoesophageal voice prosthesis: Blom-Singer versus Provox

OBJECTIVES: Compare the most commonly used types of tracheoesophageal voice prostheses, Blom Singer and Provox. STUDY DESIGN: Prospective study of 113 prostheses placed in 52 patients randomly selected to receive Blom-Singer and Provox. METHODS: Postoperative voice was recorded at 1 and 4 months after valve placement. Survival time of the prosthesis and four objective voice parameters were analyzed. Eight judges rated all recordings in a random order for six subjective voice parameters. Subgroup analysis for primary versus secondary placements and type of procedure was performed. In addition, patients were asked for their subjective assessment. RESULTS: Overall, Blom-Singer and Provox prostheses give very similar voice quality, lifetime, and patient satisfaction. Cleaning management is somewhat better for Provox, but there is a trend toward better overall voice quality for the Blom-Singer prosthesis. In subgroup analysis secondarily placed prostheses score somewhat better than primary placements, and patients with total laryngectomy have better voices than patients with extended laryngectomy combined with partial pharyngectomy. CONCLUSIONS: Given the equal and good results in terms of voice quality, other factors (e.g., costs, surgery-related factors, maintenance, patient preference) should be taken into account when deciding which type of tracheoesophageal voice prosthesis to use.     

Generation, Microwave Spectrum, and Ab Initio MO Calculation of trans-1-Nitrosopropene, CH3CH&dbond;CH-NO (syn form)

With the increasing worldwide spread of the Isshiki technique for external vocal fold medialization, some disadvantages and limitations have also emerged. and an increasing demand for a ready-made and standardized implant system can be observed. For this reason. I started experimental and clinical investigations with the goal of replacing the silicone with a safer material, and also simplifying and standardizing the surgical procedure. In particular, the danger of implant dislocation should be excluded with greater certainty. As a result, I have developed an implant made of medical-grade titanium. My surgical experiences in 20 patients with this newly developed titanium vocal fold medializing implant revealed that vocal fold medialization could be performed easily and that no perioperative complications occurred in any case. The major advantage was a significant reduction of operative time due to the preformed implant. This is not only more convenient for both the surgeon and the patient, but is also critical for obtaining optimal results due to the reduced intralaryngeal swelling and hematoma. The reduction of the glottic gap by the operation was statistically significant. Significant improvement of all voice parameters was achieved and demonstrated by a statistically significant reduction of the voice dysfunction index. Compared to the current techniques and implant systems, I see the following additional advantages: 1) titanium is a relatively safe implant material with excellent biocompatibility: 2) the design of the implant ensures optimal fixation and stabilization: 3) the implantation technique and handling is simple and time-saving; 4) the titanium sheet is easy to shape and adapt to the individual situation: and 5) only 2 sizes of implants, and no expensive instruments, are required.     

Changes in photon dose distributions due to breast prostheses

PURPOSE: Subcutaneous prosthetic implants had been routinely used for cosmetic augmentation and for tissue replacement following mastectomy over the last 15 years. The implants come in many forms as the gel filler material and surrounding shell material(s) vary significantly. METHODS AND MATERIALS: This study uses a thin window parallel-plate chamber and thermoluminescent dosimeters to quantify and dosimetric changes to surrounding breast tissue due to the presence of the prosthesis. A mammographic phantom was compared to four commercial prostheses, namely two silicon gel fillers within two different shells (silicon or silicon/polyurethane), a tri-glyceride within silicon and a bio-oncotic gel within silicon/polyurethane. The latter two implants were designed with a low-Z fill for diagnostic imaging benefits. RESULTS: Ion chamber results indicate no significant alteration of depth doses away from the implant with only minor canceling (parallel opposed) interface perturbations for all implants. In addition the physical changes to the irradiated prostheses were quantified by tonometry testing and qualified by color change. Each implant exhibited color change following 50 Gy, and the bio-oncotic gel became significantly less formable following irradiation, and even less formable 6 weeks postirradiation. CONCLUSION: The data indicates that prostheses do not affect the photon beam distribution, but radiation does affect the prostheses.     

Silicone breast prosthesis and rheumatoid arthritis: a new systemic disease: siliconosis. A case report and a critical review of the literature

Today the number of women receiving breast implants of silicone gel, for augmentation or reconstruction of the breast, is increasing. Silicon implants may cause local complications (such as capsular contracture, rupture, closed capsulotomy, gel "bleed", nodular foreign body granulomas in the capsular tissue and lymph nodes) or general symptoms. An adverse immune reaction with signs and symptoms of rheumatoid disorders is also possible, although an increased frequency of true autoimmune systemic connective tissue diseases is controversial. The US Food and Drug Administration advised that these silicone implants should be used only in reconstructive surgery and as part of clinical trials. Silicone is not an inert substance and silicone compounds were found in the blood and liver of women with silicone breast implants. The development of disease related to silicone implants would depend on genetic factors, so that only a very few women are potentially at risk. HLA-DR53 may be a marker of predisposed subjects. Breast-feeding by women with silicone implants should not be recommended for possible autoimmune disorders in the children. We report the case of an adult female patient with silicone breast implantation for bilateral mastectomy (performed 12 months before) and a unique syndrome characterized by low-grade fever, chronic fatigue, arthralgias of the hands, dysphagia, dry eye, increased level of rheumatoid factor and decreased value of complement C3 and C4. No increased erythrocyte sedimentation rate occurred, and no ANA, nDNA, ENA and AAT autoantibodies were evidence. A critical review of literature (source: MEDLINE 1980-1997) was performed and our case seems to be the first one reported in Italy. The internist should become familiar with the immunological disorders related to silicone breast implants, often so marked to require the explantation of the prostheses to improve symptomatology. However, perhaps due to the leak and spreading of silicone, the progression to a severe systemic involvement may remain despite the implant removal.     

Interposition arthroplasty of the carpo-metacarpal joint of the thumb

Nine patients with osteoarthrosis of the carpo-metacarpal joint of the thumb were treated surgically with the metacarpo-trapezial silicone rubber prosthesis designed by Kessler. Patients with pantrapezoidal changes were specifically excluded. All patients at follow-up had chronic synovitis and in five the prosthesis was dislocated. In three patients who had revision operations the previously inserted prostheses were found to be badly torn.     

The use of a silicone gel prosthesis in the treatment of post-prostatectomy incontinence

Eighty-three patients with post-prostatectomy urinary incontinence were treated by silicone gel prostheses implanted over the bulbous urethra. The prosthesis provides continence by passively increasing the urethral resistance. Successful results were achieved in 72% of patients. The mechanism of post-prostatectomy incontinence and the development of anti-incontinence surgery is briefly reviewed.     

Internal mammary silicone lymphadenopathy mimicking recurrent breast cancer

This case describes a unique complication of silicone breast implantation that is previously undocumented. Internal mammary silicone lymphadenopathy mimicking breast cancer recurrence represents an important new clinical entity. The diagnosis and management of this clinical enigma are challenging. In our patient, videothoracoscopy proved to be minimally invasive and allowed complete resection of the entire chain of pathologic nodes. Explantation of the silicone prostheses and complete capsulectomy are indicated. Light microscopy alone can suggest the diagnosis of silicone lymphadenopathy. Infrared spectral analysis can be a helpful adjunct to allow an unequivocal diagnosis.     

Prosthetic replacement of the ureters

STUDY AIM: The aim of this study is to demonstrate the reliability of silicone prosthesis for the replacement of ureters. This prosthesis derives from the biliary prosthesis developed after a personal experimental study continued by Triboulet. PATIENTS AND METHODS: In 38 patients suffering from a malignant disease, a right silicone prosthesis was used for the replacement of an ureter during a 20-year period. There were 30 female and eight male patients. The mean age was 71 (range: 51-88 years). Forty one prostheses were used; one patient underwent two successive operations on the same side with a change of prosthesis, and two patients required a bilateral prosthesis. There were 12 gynaecological carcinomas (three with ureteral fistula), three prostatic carcinomas, 16 cancers of the rectum and recto-sigmoid junction, four cancers of the right colon with retroperitoneal carcinomatosis, and three ureteral fistulas after extended colonic resection. RESULTS: Early complications were limited to ureteral fistulas (n = 6, 16%) in patients who had already a preoperative fistula (n = 3) and in patients with peritoneal metastases on the superior wall of the bladder. The secondary destruction of the kidney (four secondary nephrectomies) occurred when the function of the kidney was already impaired at the time of the procedure. There were no secondary fistulas, no secondary obstruction of the prosthesis. The longest follow-up was 69 months. CONCLUSION: The silicone prostheses used for the replacement of ureters are reliable and still permeable beyond 5 years. The protection of the renal function in patients often submitted to chemotherapy improves the duration and quality of survival. These prostheses must be reserved to advanced malignant diseases with a rather long life expectancy.     

Successful chemotherapy in a patient with recurrent carcinoma of the urachus

OBJECTIVE: Titanium in other parts of the body, well known for its biocompatibility, was examined in an animal model for its use as an ossicular replacement material. STUDY DESIGN: The biocompatibility of titanium was studied in the middle ear of rabbits using light and scanning electron microscopy. Titanium pins were placed as middle ear prostheses or as free implants and were examined after 28, 84, 168, and 336 days. RESULTS: After 28 days, the prostheses were covered by regular mucosa. The free implants took up to 336 days to be totally epithelialized. There were no inflammatory cells observed on the surface of the material nor were unusual amounts of fibrous tissue seen. In addition, the titanium material exhibited an affinity toward bone. CONCLUSIONS: The results of this animal experiment indicate that titanium is a useful material for ossicular replacement prostheses.     

Etiology of thrombosis: relationship to blood platelets

The Nijdam voice prosthesis is an indwelling valveless voice prosthesis for postlaryngectomy voice rehabilitation. The in vitro aerodynamic characteristics are reported to be comparable to that of the low-resistance Groningen voice prosthesis. Owing to the design of the prosthesis the airflow resistance depends on the shaft length of the voice prosthesis in relation to the thickness of the tracheo-oesophageal wall. As tissue characteristics of the patient's oesophageal mucosa could also be of importance, an in vivo study was found necessary. To assess in vivo characteristics the following parameters were recorded in 10 patients: intratracheal pressure, intraoesophageal pressure and airflow during phonation. At an airflow of 0.15 1/sec the transdevice pressure loss varied from 0.5 up to 7 kPa (mean 3.9 kPa). With an artificial increase of the tracheo-oesophageal wall thickness, transdevice pressure losses up to 13 kPa were found. Significant interindividual as well as intraindividual differences were noted. The airflow resistance of the Nijdam voice prosthesis in relation to the thickness of the tracheo-oesophageal wall was compared with the airflow resistance reported for various other voice prostheses. The in vivo aerodynamic characteristics of the Nijdam voice prosthesis found in this study indicate the need to modify the present design in order to improve its airflow resistance and to eliminate the influence of the thickness and tissue characteristics of the tracheo-oesophageal wall.     

In vitro and in vivo efficacy of a rifampin-loaded silicone catheter for the prevention of CSF shunt infections

Infection of cerebrospinal fluid (CSF) shunts is one of the major complications associated with their use and is usually managed by shunt removal, temporary insertion of an external drainage and implantation of a new shunt system. We have evaluated the efficacy of a rifampin-loaded silicone ventricular catheter to prevent bacterial colonization and infection in vitro and in an animal model. On the basis of an incorporation process a rifampin-loaded catheter was developed which is capable of releasing rifampin in bacteriocidal concentrations for 60 days and more. In a stationary bacterial adherence assay using S. epidermidis as test strain, the colonization resistance of the device was demonstrated. To assess the capability of the catheter to prevent CSF shunt infections, a rabbit model was developed which allowed the establishment of a reliable and reproducible CSF infection by implantation of silicone catheters into the ventricle and inoculating S. epidermidis (minimal dose 10(6) cfu) or S. aureus (minimal dose 10(3) cfu). Rifampin-loaded catheters (12 animals inoculated with S. epidermidis, 8 animals inoculated with S. aureus) were compared with non-loaded (14 animals inoculated with S. epidermidis, 19 animals inoculated with S. aureus) control catheters, and infection was documented by clinical, microbiological and histological methods. In contrast to the control group, none of the animals with rifampin-loaded catheters showed clinical signs of infection. Furthermore, in none of the materials obtained after sacrifice of the animals (catheter, brain tissue, CSF, blood) could the infecting bacteria be cultured, whereas in materials from animals with the unloaded catheter the infecting strains could always be cultured from the catheter and from surrounding brain tissue. The histological examination of catheter-adjacent tissue supported these findings. We conclude that a rifampin-loaded silicone ventricular catheter is capable of completely preventing bacterial colonization and infection by staphylococci as the main causative organisms in CSF shunt infections and should be further evaluated in clinical trials.     

Liver transplantation for hepatitis C-associated cirrhosis in a single Australian centre: referral patterns and transplant outcomes

Replacement of the tracheal conduit remains an unresolved problem. The microporous material expanded polytetrafluorethylene (ePTFE) is suitable for tracheal reconstruction. The aim of our study was to improve the limited mechanical properties of this material by incorporating reinforcement elements and to examine the influence of these elements on host incorporation and epithelialization. In so dours ePTFE prostheses were reinforced with lonomer cement and porous high density polyethylene (pHDPE) rings and implanted into the neck muscle of miniature pigs. One of these prostheses was epithelialized by a cell seeding technique and was thus placed into a tracheal defect. Results were examined grossly by endoscopy and than by light and scanning electron microscopy. The shapes of both types of prostheses showed a high stability. The reinforcement elements did not impair bioincorporation or the ability to epithelialize. In vivo interposition of an incorporated and epithelialized prosthesis to a host led to cell differentiation. The improved biomechanical properties of the prostheses waid and the reproducible formation of epitheliums are important advances in the solution of effectively correcting tracheal defects.     

The further development of a human, alloplastic tracheal prosthesis

The present paper discusses the design, construction and characterization of human alloplastic tracheal prostheses. Two different types of construction, the spiral and the clasp prosthesis, have been developed. The prostheses are composite constructions comprising a silicone tube and a polyethylene reinforcement connected together by means of a biocompatible adhesive. The results of various mechanical examinations (stress-strain behavior, torsional strength, compressibility, bending stiffness, fatigue testing) show that some of the 14 prostheses investigated approach the human trachea in terms of mechanical properties, and may be considered suitable. Suggestions for further improvements are made.     

Medialization laryngoplasty

Medialization laryngoplasty was performed in 25 patients between 1993 and 1997. The underlying pathology resulting in glottal incompetence was vocal cord paralysis in 22 patients and vocal cord bowing in 3 patients. Two types of implants were used: self-carved Proplast in 19 patients and prefabricated hydroxyapatite prostheses in 6 patients. Preoperative and postoperative results were compared in terms of dysphagia, vocal quality as graded by three experienced voice specialists, and computer measurements of the glottal gap. All patients showed improvement both subjectively and on the objective measurements used. Swallowing returned to normal in all patients who had isolated recurrent laryngeal nerve paralysis. The voice improved in all patients but was rarely judged as entirely normal.     

Investigation of a rifampin, fusidic-acid and mupirocin releasing silicone catheter

After strict hygienical measures have been exhausted the use of plastic materials with antibacterial activity may reduce catheter related-bacterial colonization. An antimicrobial silicone catheter was investigated by HPLC-measurement, SEM, antimicrobial assays and standard biocompatibility tests. The modified catheter was highly biocompatible and the antimicrobial leaching non-toxic. The initially release rate was governed by the drug solubility in the 'sink' and surface loading ('burst effect'). The second continuous period depended on the drug velocity in the silicone matrix and was extended up to 100 days with a proportionality to square root of t for each drug. Diffusion exponents were in range of 2 x 10(-8) to 1 x 10(-9) (cm2 sec(-1)). The lower diffusion exponent of mupirocin was explained by its higher cohesion energy and lower physico-chemical compatibility with the embedding silicone. The antimicrobial drugs were in a molecular-dispersed state with the silicone-matrix, whereas superficially located crystals of the antibiotics covering the catheter surface could be demonstrated by SEM.     

Titanium and bioactive glass-ceramic coated titanium as materials for keratoprosthesis

The current problem with keratoprosthesis is the ingrowth of corneal or conjunctival epithelium into the anterior chamber. This may lead to infections and extrusion of the prosthesis as well as to the development of retroprosthetic membrane and secondary glaucoma. Glass-ceramic coated and uncoated titanium has been tested as material for the keratoprosthesis to prevent epithelial ingrowth. Twenty-two Supra-Descemet's membrane keratoprostheses were inserted in the eyes of 22 rabbits for 1, 2, 4, 8, or 12 months. The prosthesis had an optic part made of polymethylmetacrylate (PMMA). The support for the optic part and the flange of the prosthesis were made of titanium. Eleven of the prostheses were coated with glass-ceramic. The histological sections of the enucleated eyes were prepared through the central part of the cornea and the prosthesis using a cutting-grinding method. The histological analysis was made on both halves of the implants separately giving two analysis areas in each eye. All 11 titanium prostheses were retained for the time period planned. Two glass-ceramic coated prostheses were lost at 2 and 4 weeks, respectively. This was caused by difficulties at surgery due to a thick coating. These eyes were excluded from the histological analysis. No significant ingrowth of epithelium was seen in 15/18 (83%) and in 16/22 (73%) of the analysed areas of the glass-ceramic coated and titanium prostheses, respectively. Titanium appears to be a suitable material for the keratoprosthesis. The ingrowth of the epithelium may be hindered further by coating the titanium with bioactive glass-ceramic.