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Biomedical subjects

M Talja

Publications and source records attributed to M Talja.

At least 37 records · Page 2Linked to original sources

Cytotoxicity testing of a new caprolactone-coated self-expanding bioabsorbable self-reinforced poly-L-lactic acid urethral stent.

Forty to 75% of strictures recur within 2 years of urethrotomy and the essential problem remains how to prevent the edges of the cut stricture from adhering to each other and the scar from shrinking. To solve this problem different kinds of urethral stents have been used. Recently a new bioabsorbable self-expanding urethral stent was developed by our group. The core consists of self-reinforced (SR) poly-L-lactic acid (PLLA) and the coating is made of an amorphous copolymer of caprolactone and D,L-lactic acid [P(epsilon-CL/ D,L-LA)]. The aim of our present study was to test the cytotoxicity of the new material used to coat the SR-PLLA urethral stent utilizing the thymidine incorporation method (DNA synthesis inhibition test). The new materials showed no acute toxicity and can be regarded as biocompatible in medical devices.

Animals↗

New bioabsorbable polylactide ureteral stent in the treatment of ureteral lesions: an experimental study.

OBJECTIVE: To evaluate the suitability of a new biodegradable double-helical spiral self-reinforced poly-L,D-lactide copolymer (SR-PLA 96; L/D ratio 96/4) stent as a device for ureteral stenting in respect to changes in kidney function during the biodegradation process. MATERIALS AND METHODS: Sixteen dogs were used as experimental animals and were subdivided into two groups of eight. In Group A, both ureters were cut transversally, sutured, and stented. The right ureter was stented using an SR-PLA 96 stent, whereas a double-J C-Flex stent was used on the left side. Cystotomy was performed at 6 weeks to remove the double-J stents. In Group B, the right ureter of each dog was cut and stented in similar manner using an SR-PLA 96 stent, whereas the left ureters served as untreated controls, and cystotomy was not performed. Serum creatinine and nitrogen values were measured, urine was analyzed for signs of infection, and renal function was evaluated by urography and renography examinations preoperatively and at 6, 12, and 24 weeks postoperatively, at which time points, the dogs were euthanized and the ureters dissected to find persistent SR-PLA 96 particles and macroscopic local changes. There were no urinary tract infections found during the study. RESULTS: In the SR-PLA 96-stented ureters, obstructive hydronephrosis and stricture formation were observed in two cases (11%), with distal displacement of the SR-PLA 96 stent in another case (5.5%). In two additional renal units, a temporary prolongation in the kidney washout time was observed at 6-week renogram examinations. In the C-Flex-stented ureters, temporary changes in renography studies were observed in three cases (37.5%) at 6 weeks. Kidney washout times were protracted at 6 weeks in the pigtail-stented ureters in Group A as a sign of a pressure rise in the renal pelvis secondary to the direct connection between the renal pelvis and bladder, whereas pressure remained normal in SR-PLA 96-stented ureters. In Group B, renal function remained normal after ureteral repair in SR-PLA 96-stented ureters compared with the controls. CONCLUSIONS: The double-helical apical stent design offers some advantages over a double-J design. The risk of pressure-induced kidney damage is lowered, because there is no direct connection between the bladder and renal pelvis, and the risk of upper urinary tract infections is reduced. The biodegradation of the device necessitates the removal of the stent. These preliminary results suggest that a biodegradable SR-PLA 96 stent with more effective expansion capacity can be used for stenting after a ureteral repair.

Absorbable Implants↗

Tissue biocompatibility of a new caprolactone-coated self-reinforced self-expandable poly-L-lactic acid bioabsorbable urethral stent.

BACKGROUND AND PURPOSE: The bioabsorption time as well as other properties of bioabsorbable polymers can be affected by the choice of the basic molecule, by the degree of its polymerization, and by the coating material used in the device. The aim of our present study was to evaluate the biocompatibility of a new caprolactone copolymer-coated, self-reinforced poly-L-lactic acid (SR-PLLA) urethral stent by means of a rabbit muscle implantation test. This new material has previously been tested for cytotoxicity using the thymidine incorporation method (DNA synthesis inhibition test), no toxicity being evidenced. MATERIALS AND METHODS: Fifteen male rabbits were used as experimental animals. Rods made from pure lactic acid, pure caprolactone copolymer, and caprolactone-coated lactic acid were placed on both sides of the dorsal muscles, eight implants per rabbit. Rods made from latex and silicone were used as positive and negative controls, respectively. The animals were sacrificed after 1 week, 1 month, or 6 months. Tissue reactions around the implants were analyzed and scored semiquantitatively. RESULTS: Acute tissue reactions attributable to operative trauma were seen in all specimens at 1 week. After 6 months, chronic inflammatory changes and foreign-body reactions were seen only in the positive controls. CONCLUSION: The new caprolactone copolymer material is highly biocompatible.

Absorption↗

Biocompatibility testing of a new bioabsorbable X-ray positive SR-PLA 96/4 urethral stent.

PURPOSE: Recently a first X-ray-positive bioabsorbable urethral stent was developed by our group. The stent is made from self-reinforced poly-L,D-lactic acid (SR-PLA 96/4) blended with barium sulfate. The aim of this study was to evaluate the biocompatibility properties of the new stent materials. MATERIALS AND METHODS: Rods made from pure SR-PLA 96/4 and SR-PLA 96/4 blended with barium sulfate were inserted into the dorsal muscles of a rabbit. Rods made from latex and silicone were used as positive and negative controls. To evaluate the long-term effect of BASO4 after the bioabsorption of the polymer, fast degrading SR-PGA (self-reinforced polyglycolic acid) and SR-PLA + BASO4 rods were used as controls. Urethral stents made from SR-PLA 96/4 and X-ray-positive SR-PLA 96/4 stents were inserted cystoscopically into the rabbit urethra. Metal stents were used as controls. The animals were sacrificed after 1 week, 1 month or 6 months. RESULTS: In the muscle implantation samples acute tissue reactions due to operative trauma were seen in all specimens at 1 week. After 6 months chronic inflammatory changes and foreign body reaction were seen only in the positive controls. The stent worked well in the rabbit urethra, its biocompatibility was good and there was less encrustation than in the metal stents. CONCLUSIONS: This first X-ray-positive bioabsorbable urethral stent showed no toxic tissue effects.

Absorbable Implants↗

Finasteride following balloon dilatation of the prostate. A double-blind, placebo-controlled, multicenter study.

BACKGROUND AND AIMS: To evaluate the efficacy, safety and tolerability of finasteride administered for 24 months following successful balloon dilatation in patients with benign prostatic hyperplasia (BPH). PATIENTS AND METHODS: 75 patients with moderate to severe symptoms of benign prostatic hyperplasia were first treated with balloon dilatation. After a 4-week placebo runin period, 64 patients with successful dilatation and over 50 % reduction in symptoms were randomized to receive either finasteride (33 pts.) at 5 mg/day or placebo (31 pts.) for 24 months. Altogether 12 patients dropped out at some stage, and the final analysis hence included 27 patients in the finasteride group and 25 patients in the placebo group. RESULTS: The symptom scores increased by an average of 3.2 points in the finasteride group and 4.4 points in the placebo group during two years. The mean maximum flow in the finasteride group remained constant: 13.7 ml/s at baseline and 13.9 ml/s at 24 months. In the placebo group the mean maximum flow decreased from 13.3 ml/sec to 11.2 ml/s. During the two-year study period, neither of the groups displayed any changes in residual urine. The above mentioned changes were not statistically significant, however. Prostate volume and serum PSA were significantly lower in the finasteride group (p < 0.001). The groups did not differ with regard to side-effects. CONCLUSIONS: On the basis of the findings, BPH patients with moderate to severe symptoms can be treated with balloon dilatation. The effect of balloon dilatation is quick, and it alleviates the patients' symptoms immediately. Finasteride treatment maintains the positive effect of balloon dilatation. This combination of treatment is tolerated well and side-effects are rare. The favourable effect of balloon dilatation was maintained for at least two years. Finasteride treatment diminished significantly both prostate volume and serum prostate-specific antigen after balloon dilatation compared to placebo treatment.

Catheterization↗

A bioabsorbable self-expandable, self-reinforced poly-l-lactic acid urethral stent for recurrent urethral strictures: a preliminary report.

PURPOSE: We studied whether a new bioabsorbable self-expandable, self-retaining and self-reinforced poly-l-lactic acid double spiral stent is able to prevent the edges of a cut recurrent urethral stricture from adhering together and the scar from shrinking, thus obviating stricture recurrence. MATERIALS AND METHODS: A bioabsorbable spiral stent was inserted into the stricture site in the urethra immediately after optical urethrotomy in 22 patients with recurrent urethral stricture. Uroflowmetry, measurement of residual urine volume, urine culture and urethroscopy were performed before and 1, 3, 6 and 12 months after optical urethrotomy. RESULTS: All 22 patients voided freely on day 1 or 2 after urethrotomy. The stent slipped partially proximal to the stricture and had to be changed in only 1 patient. The stent was totally epithelialized in all but 1 patient at 6 months and had degraded in all at 12 months. The improvement in flow rate was maintained during followup except in 10 patients with stricture recurrence, which was outside the stent area usually close to the external sphincter in 7 and in the stent area in 3. All recurrences were treated with repeat optical urethrotomy and a new stent was inserted. Urinary infections developed in 2 patients and were successfully treated with oral antibiotics. CONCLUSIONS: The self-expandable self-reinforced poly-l-lactic acid double spiral stent is a promising new method in the treatment of recurrent urethral strictures. There is no need to remove the device and no foreign material remains in the urethra. However, longer followup and controlled studies are needed to evaluate all benefits and side effects of this new treatment modality.

Absorbable Implants↗

The importance of fluorescence distribution and kinetics of ALA-induced PpIX in the bladder in photodynamic therapy.

Photodynamic therapy (PDT) is a new anticancer technique directed at the selective destruction of neoplastic tissue. Aminolevulinic acid (ALA), a precursor in the biosynthesis of home, induces the production of the endogenous photosensitizer protoporphyrin IX (PpIX). In this study the fluorescence distribution of ALA-induced PpIX was investigated in the rat bladder wall by fluorescence microscopy. The fluorescence studies showed that PpIX concentrates in bladder mucosa and that the highest fluorescence levels are achieved after four hours of 300 mg/kg ALA administration. A clear trend in difference between mucosa and muscularis layers was found in all samples taken after 1, 2, 4 and 6 hours of ALA administration. Our results suggest that to get the highest PpIX fluorescence intensity in bladder mucosa it is best to use 300 mg/kg ALA administration. Four hours is the time point when the highest difference in fluorescence between mucosa and muscularis is reached.

Aminolevulinic Acid↗

The biodegradable self-reinforced poly-DL-lactic acid spiral stent compared with a suprapubic catheter in the treatment of post-operative urinary retention after visual laser ablation of the prostate.

OBJECTIVE: To evaluate the efficacy and safety of a biodegradable self-reinforced poly-DL-lactic acid (SR-PLA) spiral stent compared with a suprapubic catheter after visual laser ablation of the prostate (VLAP) in a randomized study. PATIENTS AND METHODS: The study comprised 45 patients (mean age 67.6 years, range 52-81) with bladder outlet obstruction caused by benign prostatic hyperplasia who received either a SR-PLA stent (22 patients) and a suprapubic catheter, or a suprapubic catheter only (23 patients) after undergoing VLAP. The suprapubic catheter was removed when voiding started. The response to VLAP and the effect of the stent or catheter were assessed using symptom scores, peak flow rate (Qmax), post-void residual volume (PVR), stent degradation, infection and outcome. RESULTS: Voiding started on the first or second day after treatment in 18 (median one day) of 22 patients with a spiral stent and in eight (median 6 days) of 23 patients with only the suprapubic catheter. The mean degradation time of the SR-PLA stent was 6 months; spiral fragments were found in the prostatic urethra or the urinary bladder in 20 of the patients on cystoscopy. Improvements in patient-weighted symptom score, mean Qmax and PVR were significant in both groups at the 6 month follow-up. The infection rate increased with the duration of suprapubic catheterization, from 25% (0-3 days) to 44% (> 3 days). Stones were seen in two stented patients during the follow-up. CONCLUSION: The SR-PLA spiral stent is safe and effective for the treatment of post-operative urinary retention after laser therapy. The degradation time of the stent was unnecessarily long compared with the duration of prostatic swelling and tissue sloughing after laser therapy. The infection rate depends on the duration of suprapubic catheterization.

Aged↗

Effects of biodegradable self-reinforced polyglycolic acid, poly-DL-lactic acid and stainless-steel spiral stents on uroepithelium after Nd:YAG laser irradiation of the canine prostate.

OBJECTIVE: To evaluate the safety and tissue effects on canine uroepithelium and prostate of biodegradable self-reinforced polyglycolic acid (SR-PGA) and self-reinforced poly-DL-lactic acid (SR-PLA) spiral stents compared to stainless-steel (SS) spiral stents. MATERIAL AND METHODS: Twenty-five dogs (median body weight 12 kg) underwent a one-stage midline laparotomy and cystotomy. A side-firing Nd:YAG laser fibre was placed in the prostatic urethra antegradely and laser power applied at a setting of 20 W for 10 s in each side lobe, followed by dilatation to 4 mm diameter and insertion of a spiral stent. Dogs were randomized to receive an SR-PGA, SR-PLA or SS stent and no catheter was placed post-operatively. The dogs were killed after a follow-up of 1, 3 or 6 months and the bladder, prostate and urethra removed. Routine histological sections were prepared from the bladder, prostate, the proximal urethra immediately below the prostate and the distal urethra. RESULTS: Histological examination showed a mild to moderate foreign-body reaction and an acute inflammatory reaction after 1 month in the SR-PGA and the SR-PLA groups. The tissue effect was minimal in the SR-PGA group after 6 and 12 months. The SS stent group had more fibrosis, chronic inflammation and oedema at all follow-up assessments. There were erosions of the epithelium with subepithelial oedema in the animals with the SS stent. No dysplasia was detected and some remnants of the suture material were evident in the area of the cystotomy closure. There was one stricture at the apex of prostate in the SR-PGA group at 3 months in one re-operated dog. CONCLUSION: The histopathological changes in tissues caused by SR-PGA and SR-PLA stents were generally minor and decreased during the follow-up. The biocompatibility of SR-PGA and SR-PLA stents was good when combined with Nd:YAG laser treatment of the prostate.

Animals↗

Immersion in antibiotic solution prevents bacterial adhesion onto biodegradable prostatic stents.

OBJECTIVE: To determine whether immersion in antibiotic solution reduces or prevents bacterial adhesion onto biodegradable prostatic stents. MATERIALS AND METHODS: Pre-cut segments of polyglycolic acid (PGA) and polylactic acid (PLA) prostatic stents were incubated with two common uropathogenic bacterial strains (Enterococcus faecalis and Escherichia coli) with and without previous immersion in antibiotic solution. Tobramycin, ceftriaxone and ciprofloxacin solutions were used, as these antibiotics are commonly administered for the prophylaxis and treatment of urinary tract infection (UTI). RESULTS: Immersion in ciprofloxacin solution prevented the adherence of both bacterial strains. Immersion in ceftriaxone solution prevented only the adherence of the E. coli strain. Immersion in tobramycin solution had no effect on either of the strains. The stent materials per se did not influence bacterial adhesion. After immersion in ciprofloxacin, the stent segments retained significant antibacterial activity even after one day's incubation in saline. CONCLUSION: Immersion in a suitable antibiotic solution may significantly reduce and even prevent bacterial adhesion onto biodegradable prostatic stents. Preventing bacterial adhesion may reduce the risk of UTI during the use of these devices.

Anti-Bacterial Agents↗

Bioabsorbable and biodegradable stents in urology.

Since the early 1970s, bioabsorbable polymers have been used increasingly as suture and device materials. Bioabsorbable materials are high-molecular-weight polymers of polylactide (PLA; poly[lactic acid]) or polyglycolide (PGA; poly[glycolic acid]). The mechanical properties of self-reinforced (SR) devices (SR-PGA, SR-PLLA, and SR-PLA96 spiral stents) are acquired by special processing methods from polymer materials. As a result, the spiral stent has an expansion property of up to 70% of its original outer diameter, 50% of which may occur in 30 minutes. The stent may also have variable degradation properties in different parts of the device. The use of bioabsorbable devices in urology is novel. Today, SR-PGA spirals (Biofix) to be used for the prostatic urethra are commercially available but with restrictions. Their indications are the prevention of urinary retention after thermal therapy of prostatic hyperplasia, temporary treatment of urinary retention in patients waiting for surgery, and the early-phase resolution of bladder outlet obstruction in patients waiting for the effect of medical therapy. Stents can be also used to observe the effects of prostatic surgery on bladder function. The SR-PLLA and SR-PLA96 spiral stents are still under development for use in the anterior urethra, prostatic urethra, and ureters. Further experimental and controlled clinical studies are needed to find out the suitability of bioabsorbable devices in urology. Many efforts have been made to discover the best possible materials, models, coating materials, and additives of bioabsorbable stents in urology.

Absorption↗

A randomized study to compare biodegradable self-reinforced polyglycolic acid spiral stents to suprapubic and indwelling catheters after visual laser ablation of the prostate.

PURPOSE: A randomized controlled study was done to evaluate the efficacy of the self-reinforced polyglycolic acid spiral stent compared to a suprapubic catheter, and combined suprapubic and indwelling catheters in the prevention of urinary retention after visual laser ablation of the prostate. MATERIALS AND METHODS: We studied 72 men with benign prostatic hyperplasia who underwent placement of a suprapubic catheter and visual laser ablation of the prostate. In 27 men in group 1 the self-reinforced polyglycolic acid spiral stent was inserted into the prostatic urethra after visual laser ablation of the prostate, while 23 in group 2 received no other devices. In 22 men in group 3 an indwelling catheter was left in situ for an average of 6.5 days. RESULTS: Voiding began 1 or 2 days postoperatively in 20 of 27 patients (median 1 day) in group 1, and 8 of 23 (median 6 days) in group 2. In 16 of 22 men in group 3 voiding began 1 or 2 days (median 6) after removal of the indwelling catheter. Improvements in patient weighted symptom score, mean peak urinary flow rate and post-void residual volume were significant (p < 0.001) at 6 months of followup in all groups. The overall infection rate was 30%. CONCLUSIONS: The self-reinforced polyglycolic acid spiral stent is superior to the suprapubic catheter alone, and to combined indwelling and suprapubic catheters for the treatment of postoperative urinary retention after laser therapy, offering possibilities for shorter catheterization time.

Aged↗

Biocompatibility of latex and silicone T tubes in the porcine common bile duct: an experimental study.

Toxicity of materials used in indwelling drains or catheters has the potential to damage surrounding tissues. The biocompatibility of biliary T-tubes was investigated using in groups of piglets (total 30 animals). In group 1 (n=16) a choledochotomy was performed with insertion of a latex T-tube (n=6) or a silicone T-tube (n=8), or without a T-tube (n=2). In group 2 (n=14) the common bile duct (CBD) was 3/4-transected, and the lesion was sutured over a latex T-tube (n=4) or a silicone T-tube (n=5), or without a T-tube (n=5). The groups were reoperated upon after 2 and 6 weeks respectively, and the CBD was harvested for scanning electron microscopy and light microscopy. The T-tubes were examined for cell culture toxicity with a DNA synthesis inhibition test. According to the cell culture tests, latex T-tubes were toxic and silicone T-tubes nontoxic. T-tubes induced moderate to pronounced fibrosis and epithelial damage in the CBD wall, but did not induce excessive fibrosis or scarring at the site of CBD suture. In the 6-week study period, however, the grade of tissue reactions in the CBD did not correlate with the toxicity of the T-tube materials, but rather reflected a foreign body reaction and mechanical pressure. Although gross anatomical changes did not occur, neither material seemed to be completely harmless for porcine CBD wall.

Animals↗

Bacterial adherence and biofilm formation on latex and silicone T-tubes in relation to bacterial contamination of bile.

BACKGROUND: T-tube-related bacteriobilia causes infectious complications and obstruction. To prevent these, the choice of T-tube material may be of importance. METHODS: Transected common bile ducts (CBDs) of 17 piglets were sutured over latex or silicone T-tubes, or without a T-tube. RESULTS: After 6 weeks bacteriobilia was found in all of 12 CBDs with and in 1 of 5 CBDs without a T-tube (p < 0.05). By scanning electron microscopy (SEM) four of five latex and none of five silicone T-tubes had bacterial biofilms (p < 0.05). All tubes remained patent. Segments of T-tubes were incubated with five different bacterial strains. Sonication and SEM showed that 0.1-1.1% of 10(7) colony-forming units of inoculum adhered to T-tubes. Two to six times more bacteria adhered to latex than to silicone (p < 0.05). CONCLUSIONS: Silicone offers better long-term patency than latex. Less infectious complications occur if T-tubes are omitted.

Animals↗

Bacterial adhesion and biofilm formation on various double-J stents in vivo and in vitro.

The aim of this study was to determine whether bacterial adhesion and biofilm formation occur on various ureteric stent materials in vivo and in vitro and whether there is any correlation between biofilm formation and urinary tract infection. Using an open surgical procedure, 23 double-J stents of 8 different types were inserted in the ureters of 13 piglets. After 6 weeks intubation, 2 (9%) of the 23 stented renal units yielded positive urine culture. Scanning Electron Microscopy (SEM) showed sporadic bacteria on 7 (30%) of the 23 indwelling ureteric stents and bacterial biofilms on only 2 (9%), those indwelling the renal units which yielded positive urine cultures. Precut segments of the 8 double-J stent brands were incubated with 5 different bacterial strains. Microbiological and SEM analysis of the stents revealed that only 0.1-0.01% of the bacterial inoculum adhered to the stents. There was no statistically significant difference in bacterial adherence to the various stent materials. Interestingly, the two Escherichia coli strains with P-fimbriae adhered significantly more than the two without P-fimbriae. Sporadic bacterial adhesion to ureteric stents seemed to have little clinical significance whereas biofilm formation seemed to result in urinary tract infection. None of the tested stents proved to be superior to the others in this respect, and adhesion appeared to depend on the virulence of the bacteria rather than the properties of the biomaterials.

Animals↗

Mitotic activity and prognosis in prostatic adenocarcinoma.

Mitotic figures were quantitated by two different methods (number of mitotic figures in 10 high power fields, MI; number of mitotic figures/mm2 of neoplastic epithelium, M/V) in a series of 303 prostatic adenocarcinomas, and the results were related to clinical and histological features as well as to prognosis. Gleason score and mitotic indices were significantly interrelated. Invasive T3-4 tumors showed higher mitosis counts than did the local ones, and metastasis at the time of diagnosis was related to mitotic indices as well. Progression and progression-free survival were related significantly to Gleason score and mitotic indices. In univariate survival analysis, T-category, M-category, Gleason score, MI, and M/V were significant prognostic factors. In multivariate analysis, independent predictors of survival were M-category, T-category, Gleason score, patient age, and the M/V index. If the Gleason score was not included, M/V included all the available prognostic information in T1-2M0 carcinomas. The results show that, in addition to the conventional Gleason grading system, mitotic indices are useful prognostic parameters while evaluating the long-term prognosis in prostatic adenocarcinoma.

Adenocarcinoma↗

Nuclear morphometry is of independent prognostic value only in T1 prostatic adenocarcinomas.

A series of 325 patients with prostatic adenocarcinoma followed-up for over 13 years was subjected to histomorphometric analysis for the following prognostic factors: the Gleason score and 10 nuclear morphometric factors (mean nuclear area, nuclear perimeter, shortest and longest nuclear axis, form factor and their SDs), using the IBAS 1&2 image analyzer. Nuclear factors, Gleason score (P = 0.0013-0.0148), and T-category (P = 0.004-0.0107) were significantly interrelated, while the M-category was independent of the morphometric parameters. Nuclear factors (P = 0.0003-0.5), Gleason score (P < 0.0001), T-category (P < 0.0001) and M-category (P < 0.0001) predicted the disease outcome. In T1-2M0 tumors, the T-category (P = 0.0001), Gleason score (P < 0.0001), SD of nuclear area (P = 0.057), SD of nuclear perimetry (P = 0.039), mean shortest nuclear axis (P = 0.030), SD of the shortest nuclear axis (P = 0.0045), SD of the longest nuclear axis (P = 0.009), and nuclear form factor (P = 0.0123) were significant prognostic factors. In the multivariate survival analysis, the nuclear area had independent prognostic significance only in T1 tumors, whereas in other subcategories, the clinical stage, Gleason score, and patient age included all the available prognostic information. The results indicate that nuclear morphometric measurements are of borderline significance only in evaluating the intrinsic malignancy of prostatic adenocarcinoma.

Adenocarcinoma↗