Use Of Polydimethylsiloxane Research Articles

ENDOSCOPIC TREATMENT OF URINARY INCONTINENCE: LONG-TERM EVALUATION OF THE RESULTS

We report on the use of polydimethylsiloxane for endoscopic treatment of urinary incontinence in children with neurogenic bladder and discuss our results to determine optimal criteria for patient selection. A total of 44 children (19 males) have been treated endoscopically for urinary incontinence since 1995. Etiology was spina bifida in 35 cases. Previous surgery had been performed on 24 patients, including bladder neck reconstruction with (17) or without bladder augmentation. Mean patient age at injection was 13 years (range 7 to 17). A single transurethral injection was given in 23 cases, 2 in 17 and 3 or more in 4. Mean volume at each injection was 3.5 cc and for each patient the total volume injected was 5.7 cc. Mean delay between 2 injections was 6 months (range 3 to 15). Followup ranged from 6 to 53 months (median 28). Of the patients 15 (34%) are dry (continent greater than 4 hours, no urinary pad during the day), 11 (25%) are improved (continent 2 to 3 hours, occasional pad) and 18 had poor results. In the entire series only gender and preoperative hyperactivity influenced the results, as the best results were achieved in females with a stable bladder (44% of girls versus 21% of boys were cured). Good results persisted at 12-month followup in patients treated with only 1 injection (until 36 months for older patients) and after the last of 2 injections. Of the patients treated with 3 or more injections 1 was dry at 12-month followup and treatment failed in 3. Injection of polydimethylsiloxane at the bladder neck achieved continence in 34% of neurogenic bladder cases. Results were better in girls with a stable bladder. Results deteriorated in the first 12 months of followup. No more than 3 injections are advised if a satisfactory result is not achieved.

Use of Polydimethylsiloxane for Constructing Amperometric Glucose-Sensing Enzyme Electrode with Low Interference Level

Glucose-sensing electrodes based on the cathodic detection of oxygen consumption through the glucose oxidase (GOx) reaction were constructed by using polydimethylsiloxane (PDMS). One electrode, a PDMS/GOx-bilayer electrode was fabricated by placing an enzyme layer on a PDMS-coated electrode, which was prepared by dip-coating from an aqueous dispersion of the siloxane polymer. Another enzyme electrode, an electrode with a PDMS layer containing lipid-modified GOx, was prepared by placing aqueous dispersions of the polymer and the modified enzyme on the base electrode surface and drying. The electrode using modified GOx could easily be prepared and suitable for measuring glucose in high concentrations (around 5 mM), compared to the bilayer-based system. On the other hand, both the electrodes could be used for the selective determination of glucose: the permselectivity of PDMS made it possible to monitor the oxygen consumption rate without serious electrochemical interferences.

Use of Polydimethylsiloxane for Constructing Amperometric Glucose-Sensing Enzyme Electrode with Low Interference Level

Use of Polydimethylsiloxane for Constructing Amperometric Glucose-Sensing Enzyme Electrode with Low Interference Level

The use of polydimethylsiloxane in the treatment of incontinence after radical prostatectomy.

To report the results of transurethral submucosal injection therapy of polydimethylsiloxane (PDS) to treat incontinence after radical prostatectomy (RP). Since 1993, about 80 retropubic RPs have been carried out at our institution each year. Severe post-operative incontinence occurred in six patients, with a mean duration of incontinence after RP of 28 months. The pre-operative evaluation consisted of cysto-urethroscopy and urodynamics. Because we have no experience with artificial sphincter implantation, transurethral injection therapy was used to treat the post-operative incontinence, using PDS (vulcanized silicone rubber particles). This material has a mean particle size of 188 microns, providing stability of the material at the injection site. The six patients with severe post-operative incontinence were treated using injection therapy with PDS. After a mean follow up of 15.5 months, five patients, who suffered from day and night incontinence and required at least five pads per day, were dry after injection therapy. One patient improved significantly but still required two pads during the day, but was continent during the night; three patients required a second injection. A mean of 7.5 mL of PDS was used per patient and the side-effects of therapy (dysuria and urinary retention) were minimal. Because PDS has excellent biocompatibility, few side-effects or complications, transurethral injection therapy using silicone particles is a justifiable procedure for treating incontinence after RP.

Use of polydimethylsiloxane subdermal implants for correcting facial deformities in Down's syndrome

The use of polydimethylsiloxane prostheses to improve facial appearance in patients with Down's syndrome is reported. In 1 year, 50 patients were treated with 120 prostheses. A follow-up of 8 to 18 months showed that a low incidence of minor complications occurred. Combined with the satisfactory results experienced, this makes the procedure safe and desirable.

The use of polydimethylsiloxane as a custom impression tray

A technique for fabrication and use of a flexible polydimethylsiloxane impression tray for final impressions of maxillectomy patients has been described.