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PubMed1996

Effect of food intake on the delivery of fluorescein as a model drug in colon delivery capsule after oral administration to beagle dogs.

The effect of food on the release time of a model drug, fluorescein (FL), has been studied after oral administration to beagle dogs in colon delivery capsule in comparison to conventional gelatin capsule and enteric capsules. The dose of FL was 30 mg for each animal. After oral administration of each test preparation in fasted or postprandial condition (100 grams of commercial solid food was given at 30 min before drug administration), blood samples were collected and plasma FL concentrations were measured spectrofluorometrically. Pharmacokinetic analysis was performed with plasma FL concentration vs. time data and the following parameters were determined; Tmax (the time when plasma FL concentration reaches to its maximum concentration), Cmax (peak plasma FL concentration), Tlag (the time when FL appeared at first into the systemic circulation), AUC (area under the plasma FL concentration vs. Time curve) and MRT (mean residence time). For gelatin capsule, mean Tmax appeared at 0.83 +/- 0.33 (S.E.) h after administration and MRT was 2.67 +/- 0.21 h in fasted condition. By feeding, Tmax and MRT increased to 1.50 +/- 0.76 h and 3.09 +/- 0.49 h. For two enteric HPMCP and Eudragit S capsules, MRT were 2.90 +/- 0.48 h and 5.24 +/- 0.32 h in fasted condition, and 11.30 +/- 1.10 h and 12.83 +/- 0.34 h in postprandial condition, respectively. Tlag also increased by postprandial administration. As colon delivery capsule, time-controlled release capsule (TCC) and two types of intestinal inner pressure-controlled release capsules (PCC) (#1 is a separate type and #2 is a seamless one) were tested. MRT of TCC was 4.76 +/- 0.29 h and 6.43 +/- 0.66 h in fasted and postprandial conditions, respectively. This capsule did not receive the effect of food intake. For #1 PCC, MRTs were 5.32 +/- 0.22 h and 12.28 +/- 0.26 h in fasted and postprandial conditions, respectively. For #2 PCC, MRTs were 5.51 +/- 0.26 h and 13.36 +/- 0.84 h in fasted and postprandial conditions, respectively. In addition, the effect of two times feedings was studied with two PCCs and longer MRTs, 28.44 +/- 1.39 h and 26.32 +/- 1.64 h, were obtained. The release time of FL from PCCs increased by postprandial administration. As compared to the results on two enteric capsules, these PCCs are thought to disintegrate in the colon. However, TCC is thought to disintegrate in the stomach after postprandial administration.

Administration, Oral↗

PubMed2006

Stable bioavailability of cyclosporin A, regardless of food intake, from soft gelatin capsules containing a new self-nanoemulsifying formulation.

AIM: We recently succeeded in preparing soft gelatin capsules containing a new self-nanoemulsifying formulation consisting of cyclosporin A (CsA), triacetin, polyoxyl 40 hydrogenated castor oil, polysorbate 20, medium chain triglycerides and medium chain mono- and diglycerides. The soft capsules containing the new formulation exhibited a significantly improved physical stability in terms of the appearance of the gelatin capsule shells and the composition of the fill mass during long-term storage, compared to commercially available soft capsules containing CsA, in which ethanol was employed as a cosolvent of CsA. In the present study, the influence of a fat-rich meal on the bioavailability of CsA from the soft capsule containing the new formulation (test drug) was evaluated and the results compared to those obtained with a representative soft capsule of CsA. VOLUNTEERS AND METHODS: A randomized, open-label, 3-way crossover study was performed in the test capsules and reference soft capsules, in a fasted state or after a fat-rich breakfast. 18 healthy male volunteers received a single dose of the reference formulation (Neoral, Novartis AG, Basel, Switzerland) or test formulation (2 capsules each, 200 mg as CsA) with 240 ml of water with a 1-week washout period between the treatments, after a fat-rich (670 kcal, 45 g fat) breakfast (for the test drug, Treatment A; for the reference drug, Treatment B) or a 12-h fasting (for the test drug, Treatment C). Serial blood samples, collected over a 24-h period after the administration, were assayed for blood CsA concentrations using a specific monoclonal radioimmunoassay. RESULTS: The differences in bioavailability parameters (i.e., AUC(0-24h), AUC(0-infinity) and C(max)) between the treatments were within the range of 80-125% of the reference treatment. An analysis of variance (ANOVA) revealed no significant differences (p > 0.05) between subjects, formulations or periods. The 90% confidence intervals (CI) indicated that the differences between the treatments (Treatments A and B, Treatments A and C) were also within the criteria. CONCLUSION: These results indicate that the bioavailability of CsA from the test drug is equivalent to reference in the fed state, and is likely to be less influenced by a fat-rich meal. Therefore, the new formulation of CsA using triacetin appears to have an advantage over the commercial soft capsules of CsA using a volatile cosolvent such as ethanol.

Administration, Oral↗

PubMed2003

Formulation and evaluation of sustained release floating capsules of nicardipine hydrochloride.

Nicardipine hydrochloride, a calcium channel blocker with significant vasodilating and antihypertensive activities, was formulated in this work as sustained release floating capsules. A hydrocolloid of high viscosity grade was used for the floating systems. The inclusion of sodium bicarbonate to allow evolution of CO2 to aid buoyancy was studied. Polymers that retard drug release were included as coprecipitates with the drug and/or as additives in the formulated capsules. Both simple powder mixing of the ingredients and granule preparation via wet granulation were used. Seven capsule formulae were prepared. The prepared capsules were evaluated in vitro by testing drug dissolution, floating time and the kinetics of drug release. In vitro evaluation of a commercially available conventional 20 mg capsule of nicardipine hydrochloride, "Micard", was carried out for comparison. The hydrocolloid used succeeded in effecting capsule buoyancy. Floating time increased with increasing the proportion of the hydrocolloid. Inclusion of sodium bicarbonate increased buoyancy. All of the seven floating capsule formulae prepared proved efficient in controlling drug release. The sustained release floating capsule formulation of choice was evaluated in vivo in comparison to "Micard" capsules using rabbits. Reversed phase HPLC with UV detection was used for drug determination in rabbit plasma. Plasma concentration time curves revealed a longer drug duration for administration in the sustained release formula than the conventional "Micard" capsule being 16 h in the former versus 8 h for the latter.

Animals↗

PubMed2005

Pseudophakic retinal detachment with ruptured posterior lens capsule.

The relationship between retinal detachment and posterior lens capsule rupture in pseudophakic patients was studied. Records of patients with pseudophakic retinal detachment who were admitted to Siriraj Hospital from 1992 to 2004 were reviewed. The patients were divided into 2 main groups: 1) The study group (pseudophakic retinal detachment) 79 eyes (78 cases) which was subdivided into group 1a) pseudophakic retinal detachment with intact posterior lens capsule (50 eyes), and group 1b) pseudophakic retinal detachment with ruptured posterior lens capsule (29 eyes); 2) The control group 99 eyes (90 cases) which was subdivided into group 2a) pseudophakic patients with intact posterior lens capsule (83 eyes), and group 2b) pseudophakic patients with ruptured posterior lens capsule (16 eyes). The relationship between pseudophakic retinal detachment and posterior lens capsule rupture was analyzed by Chi-square test, and risk factors were analyzed by multiple logistic regression. Retinal detachment in pseudophakic patients was found more often in males more than in females, and the average age was 57.9 +/- 11.8 years, the retinal detachment was related to posterior lens capsule rupture (p = 0.003). Patients with pseudophakic retinal detachment with a ruptured posterior lens capsule had a risk 5.7 times greater than pseudophakic patients with an intact posterior lens capsule (adjusted Odds ratio = 5.716, 95% CI = 2.118-15.427). The present study showed that posterior lens capsule rupture increased the risk of retinal detachment. Ophthalmologists should be aware of retinal detachment development after YAG capsulotomy, especially in patients who have other risk factors such as myopia, lattice degeneration, retinal break, or previous retinal detachment surgery.

Adult↗

PubMed2006

[Clinical application of wireless capsule endoscopy in pediatric and adolescent patients].

OBJECTIVE: Capsule endoscopy (CE) has been demonstrated to be safe and well tolerated in adults. However, its value in pediatric patients has not been well studied. The present study aimed to evaluate the safety and effectiveness of CE in pediatric patients with suspicious small bowel disorders. METHODS: Fifteen children and adolescents (less than 18 years) were referred to our study for suspected small bowel diseases from Aug. 2002 to May 2005. They aged from 3 to 18 years. Among them, 5 patients were less than 10 years old. The range of weight was from 17 to 83 kg and height was from 49 to 176 cm. Clinical indications included obscure gastrointestinal bleeding (n = 12) and abdominal pain (n = 3). All the patients had normal results on upper and lower gastrointestinal examinations before they underwent CE. The procedures for capsule placement, gastric transit time, small bowel transit time, the average time of the elimination of the capsule, capsule findings, and complications were recorded. RESULTS: All the patients described that the capsule was easy to swallow except 3 youngest children. Finally the capsule was delivered via gastroscopy with overtube for these three children under intravenous anesthesia. No capsule retention occurred during the study. Median recording time was (464 +/- 40) min. In 5 patients, the capsule did not pass the ileal valve by the end of the recording time. Median gastric transit time was (85 +/- 90) min. Median small bowel transit time was (283 +/- 106) min. The average time of the elimination of the capsule was (34.3 +/- 21.8) h. The detective yield of CE was 80%. These positive findings included Crohn's disease (5), hemangioma (2), angiodysplasia (2), Meckel diverticulum (1), polyp (1), and granulomatous lesions (1). CONCLUSION: CE was performed safely in pediatric patients after ingestion or endoscopic placement of the capsule. The high yield of abnormal findings was comparable to those of adult patients.

Abdominal Pain↗

PubMed1989

[Light and electron microscopy of the human, anterior cataract capsule].

Forty-three anterior lens capsules and epithelium from cataract patients extracted during extracapsular cataract surgery were examined by light microscopy and morphometry. An additional 15 lens capsules were examined by transmission electron microscopy. Morphometric examination revealed a positive correlation between age and the lens capsule thickness of 0.08 micron/year. The medium lens-capsule thickness of a 65-year-old human being was 8.65 microns. Light microscopy of cataractous anterior lens capsule and epithelium demonstrated proliferative changes with a multilamellar arrangement of the lens epithelial cells and an increase in the pleomorphic appearance of the cell and nucleus. Examination of the lens capsule revealed intracapsular foamy and vacuolic deposits with a localized splitting of the lens capsule. Transmission electromicroscopy established certain aspects of the lens capsule and epithelium. We found intracytoplasmatic single cilia and fibrillar intracytoplasmatic structures, with a diameter of 12-20 nm arranged in a pseudocrystalline fashion. The anterior lens capsule demonstrated similarly localized deviations from the normal homogeneous structure of type IV collagen, resulting in intracapsular deposition of fibrillar material. These observations suggest that cataractogenesis is associated with ultrastructural metaplastic and degenerative alteration of the lens epithelium and capsule.

Aged↗

PubMed1989

[The biomechanical properties of the crystalline lens capsule in emmetropia and myopia].

Morphometric and electronmicroscopic studies of the capsule of a clear lens depending on the degree of myopia and age as compared with the capsule of a clear lens in emmetropia and myopia have shown that with age the anterior capsule of a clear lens becomes thicker, while the posterior capsule becomes thinner and increases in length. This is connected with the weakening of accommodation in the presence of different curvature of the anterior and posterior surfaces of the lens on the background of the lowering of the metabolic level in elderly persons. In myopia, with the development of age changes the thickness of the lens capsule remains almost unchanged. The degree of myopia doesn't influence the thickness and the length of the anterior capsule of the lens, while with the rise of myopia the thickness of the posterior capsules increases. No dystrophic changes in the structure of such a capsule in high myopia were revealed. Hypertrophy of the posterior capsule speaks about the increase of its mechanic strength in a clear lens and is connected with the weakness of accommodation. Such a capsule can serve as a support for IOL implants in patients with myopic refraction.

Adult↗

PubMed1997

[Rupture of the posterior capsule and the implantation of an artificial lens].

OBJECTIVE: Study of the incidence and side effects of the posterior capsule ruptures in a clinical trial. MATERIAL AND METHODS: Retrospective study of cases with posterior capsule ruptures encountered in a series of 162 with elective extracapsular extraction and posterior chamber lens implantation. RESULTS: Intraoperative posterior capsule ruptures occurred in 16 cases (10.12%), 4 cases without vitreous loss and 12 cases with vitreous loss. 12 cases were managed by simple posterior chamber lens implantation of with scleral or iris suture; in 4 cases we preferred anterior chamber implants with flexible haptic: average postoperative visual acuity was 0.74 in the group with intact posterior capsule and 0.45 in the group with posterior capsule ruptures; average postoperative visual acuity was 2 lines higher in the group with posterior capsule ruptures without vitreous loss as compared with the group with posterior capsule ruptures and vitreous loss; postoperative complications were more frequent in the group with posterior capsule ruptures; intraocular lens descentrations were more frequent and more serious in the group with posterior capsule ruptures. CONCLUSIONS: Posterior capsule ruptures negatively affects the late functional results due to higher rate of major complications and to difficulties in artificial lens implantation.

Humans↗

PubMed2003

Influence of local complications on capsule formation around model implants in a rat model.

We studied the capsule formation around various filled breast implants and other related changes in distant organs (e.g., liver, spleen, lymph nodes) in a rat model 3 and 6 months after implantation. Model implants, one per rat, (filled with saline, n = 19; silicone, n = 14; cohesive silicone, n = 17; and hydrogel, n = 19) were implanted subcutaneous in the lower back of rats. The animals were sacrificed regularly after 3 and 6 months of implantation or when wound defects occurred. The capsules and organs were examined histologically, and immunohistology of the capsules was performed. A monoclonal antibody specific for AIF-1 (allograft inflammatory factor 1) was used to detect activated macrophages. Wound defects occurred most frequently after implantation of saline and hydrogel implants. Increased capsule thickness was associated with increased grade of inflammation, fibrosis, and the type of implant filling. There was a significant positive correlation between capsule thickness, presence of chronic inflammation, and AIF-1-positive macrophages (p < 0.0001), indicating that inflammation plays an important role in capsule formation. Remarkably, saline and silicone implants (in absence of local complications) cause only a blande slight fibrosis in capsules after 6 months of implantation, whereas capsules around cohesive silicone implants exhibited a more severe fibrosis with an increased capsule thickness. Most importantly, hydrogel seems to be most potent to induce an inflammatory infiltrate with AIF-1 expressing macrophages at the implantation site, independent of implantation time, and capsules also produced a significant increase in thickness after 6 months.

Animals↗

PubMed1994

Breast capsule contracture: is fibroblast activity associated with severity?

Factors responsible for breast capsule contracture remain elusive. Using an in vitro model of wound contraction, the fibroblast-populated collagen lattice (FPCL), breast capsule fibroblasts and control dermal fibroblasts from ten patients were analyzed. Comparison was made to determine (1) if the activity of dermal fibroblasts on a collagen lattice correlated with the activity of breast capsule fibroblasts or if capsular fibroblasts are unique, and (2) if the degree of fibroblast-driven collagen contraction correlated with clinical severity of breast capsule contracture. If so, a preoperative predictor of breast capsule contracture would be available. Dermal fibroblasts and breast capsule fibroblasts were cultured and mixed with media and collagen to form a matrix, and then the degree of lattice contraction was measured. A correlation between breast capsule fibroblasts and control dermal fibroblasts with respect to collagen matrix contraction was confirmed. Collagen lattice contraction coordinated by fibroblasts derived from breast capsules did not correlate with clinical severity of capsular contracture. These results indicate that the degree of breast capsule contracture can not be predicted by fibroblast activity alone. An interaction between inflammatory cells, extracellular matrix, and fibroblasts is hypothesized. Further work is needed to delineate the mechanisms responsible for breast capsule contracture.

Breast↗

PubMed2006

Endoscopic removal of the wireless pH monitoring capsule in patients with severe discomfort.

BACKGROUND: Few patients have significant symptoms during wireless esophageal pH monitoring, and the capsule typically sloughs spontaneously. Severe discomfort during monitoring can occur that requires endoscopic dislodgement of the capsule. OBJECTIVE: To determine the frequency with which endoscopic capsule dislodgement is required and the outcomes of the intervention. DESIGN: Chart review. SETTING: University-based outpatient endoscopy facility. PATIENTS: A total of 452 consecutive patients undergoing wireless pH monitoring over a 3.5-year period. INTERVENTIONS: Endoscopic dislodgement of the capsule by using nudging with the endoscope tip and cold snare techniques. RESULTS: Eight subjects (1.8%) required endoscopic capsule dislodgement because of severe chest pain or odynophagia (n = 7) or severe foreign-body sensation (n = 1). Chest pain was the initial indication for pH monitoring in 5 (62.5%) of the subjects. Initial nudging with the endoscope tip successfully dislodged 2 capsules; continued nudging produced mucosal stripping in 3 subjects, which required hemostasis in 1. A cold snare was used successfully, without complication, to separate the capsule from stripped mucosa and as a primary removal method in the remainder of subjects. Capsule removal uniformly resulted in marked improvement of discomfort. CONCLUSIONS: Endoscopic removal of the capsule was required in <2% of subjects who underwent wireless pH monitoring. Separation of the capsule from the mucosa with a cold snare may be the preferred method of accomplishing uncomplicated removal.

Adult↗

PubMed2002

Bladder augmentation in dogs using the tissue capsule formed around a perivesical tissue expander.

PURPOSE: Enterocystoplasty provides needed improvement in bladder storage parameters in many patients but it also generates significant morbidity. We evaluated the unusual potential alternative of using the capsule that forms around a standard silicone tissue expander placed perivesically to augment the bladder in dogs. MATERIALS AND METHODS: Six mongrel dogs underwent baseline videourodynamics and assessment of serum electrolytes, followed by placement of a 250 to 500 cc perivesical silicone tissue expander. Four months after implantation the tissue expander was removed and the fibrous capsule around the expander was biopsied. The capsule was opened and anastomosed to the bladder to augment storage. Serum electrolytes were determined 2 and 4 weeks after augmentation. Videourodynamics were repeated after 3 to 5 months, that is at sacrifice. The harvested bladders underwent histological evaluation. RESULTS: Five dogs underwent augmentation as described, while in an additional dog that underwent intraperitoneal placement of the tissue expander a fibrous capsule failed to form. Of the 5 augmented dogs 4 underwent repeat urodynamic and electrolyte evaluation with harvesting of the lower urinary tract, while 1 died of undetermined causes 3 weeks after augmentation. A distinct capsule formed in all dogs and augmentation was technically achievable. Anastomosis calcification in 3 dogs limited filling the augmenting capsule for cystography. Bladder capacity and compliance improved in all animals but it varied in degree. Histological examination of the capsule biopsies showed collagen rich connective tissue without epithelium or smooth muscle. After augmentation the capsular segment revealed urothelium in all cases with squamous metaplasia in 1. The subepithelial region had dense fibrosis and a thin band of osseous metaplasia occupied the lamina propria in all cases. Disorganized smooth muscle bundles were noted in all augmented bladders within the collagen of the capsule wall. CONCLUSIONS: Bladder augmentation with the collagenous capsule formed over a perivesical tissue expander is technically feasible. There was evidence of epithelial and smooth muscle ingrowth from the native bladder with improved bladder capacity and compliance in all dogs. Osseous metaplasia of the luminal surface of the collagen based capsule that developed in all animals may have been responsible for anastomotic narrowing and limited filling on cystography.

Animals↗

PubMed2003

Otago Glaucoma Surgery Outcome Study: factors controlling capsule fibrosis around Molteno implants with histopathological correlation.

OBJECTIVE: To describe the histopathology of Molteno implant capsules in cases of primary and secondary glaucoma and to correlate them with surgical technique and clinical outcomes in quiet eyes. DESIGN: Human tissue study with clinicopathological correlation. MATERIALS: Seventy-five autopsy eyes or surgical pathology specimens obtained between 4 days and 23 years after insertion of Molteno implants were studied. Basic histologic features common to all bleb capsules were described, and the thickness was measured in 28 specimens from quiet eyes. MAIN OUTCOME MEASURES: Histologic features of capsules, including wall thickness, distribution of inflammatory cells, and presence or absence of fibrodegeneration, were assessed by light microscopy. RESULTS: Without aqueous flow (first stage of 2-stage insertion), the episcleral plates of Molteno implants were encapsulated by a very thin (20-60 micro m) avascular collagenous layer. The second stage of 2-stage insertion, with delayed drainage of aqueous and early temporary postoperative intraocular pressure (IOP) increase to 25 to 35 mmHg, produced thin (190-250 micro m) permeable capsules with fewer fibrovascular than fibrodegenerative components. Insertion of nonligatured implants with immediate aqueous flow produced thicker capsules (300-600 micro m) composed of an outer fibrovascular layer and an inner fibrodegenerative layer of approximately equal thickness. Three-stage insertion of modified Molteno implants with temporary externalization of aqueous flow onto the conjunctival surface and postoperative IOP not exceeding 12 mmHg produced the thickest (375-700 micro m) heavily fibrosed and impermeable capsules composed entirely of dense fibrovascular tissue without a fibrodegenerative layer. CONCLUSIONS: Capsules around functioning Molteno implants evolved through a series of histologic stages. Without aqueous flow, the episcleral plate of the implant stimulated encapsulation by a thin avascular collagenous layer. With aqueous flow, an immediate inflammatory reaction developed in the episcleral connective tissues that included collagenous and vascular components. After a variable delay, a fibrodegenerative process developed in the deeper layers of the capsule. The fibrodegenerative process may depend on sufficient increases of IOP for aqueous to displace interstitial tissue fluid from the deeper layers of the capsule. The final thickness and permeability of the capsule probably depend on the relative intensity and timing of these opposing processes, which were influenced by surgical technique and postoperative management.

Adult↗

PubMed2006

Video capsule endoscopy in small-bowel malignancy: a multicenter Belgian study.

BACKGROUND AND STUDY AIMS: Early diagnosis of small-bowel tumors is crucial for therapy. Video capsule endoscopy has improved the diagnosis of small-bowel diseases, but data concerning the role of this technique in detecting small-bowel malignancy are scarce. The aim of this paper was to review all capsule endoscopy findings at Belgian hospitals, in order to evaluate the diagnostic yield of capsule endoscopy in the field of small-bowel malignancy. PATIENTS AND METHODS: For this retrospective study, the seven Belgian academic hospitals where the device was being used were asked to review the findings obtained by means of video capsule endoscopy, and to collect information about the cases of small-bowel malignancy. RESULTS: In total, 443 capsule endoscopies were performed up to November 2004, and 11 malignant small-bowel processes were detected (2.5%). The most frequent indications for performing capsule endoscopy in those 11 cases were intestinal bleeding of undefined origin or iron-deficiency anemia. The mean number of diagnostic procedures performed before capsule endoscopy was 3.6. The capsule endoscopy results had a diagnostic yield of 1.6% after classical work-up. In 55% of these cases, capsule endoscopy findings had an influence on therapy. CONCLUSIONS: Tumors of the small bowel remain a rare condition. Video capsule endoscopy is able to detect tumors undiagnosed by classical procedures in about 1.6% of cases and has an impact on the therapy in 55% of the tumor cases.

Aged↗

PubMed1994

Histologic features of breast capsules reflect surface configuration and composition of silicone bag implants.

The fibrous capsules that develop around silicone gel breast implants may become excessively thickened and result in painful hardened breasts. This article examines the microscopic anatomy of 80 periprosthetic breast capsules removed during a 2-year period (1990-1992), and describes the histopathologic characteristics of capsules adjacent to the more recently modified implant types. Capsules were examined by routine light microscopy, with and without polarization. Several distinctive histologic patterns were recognized, and these unique patterns could be correlated with the implant type used. All capsules were lined by a cellular membrane resembling synovium. Capsules adjacent to smooth-surfaced implants were lined by an intact histiocytic membrane of uniform thickness. In contrast, the membrane adjacent to textured implants varied in thickness, and was disrupted along its length. In addition, the inner surface of capsules adjacent to textured implants was conspicuously festooned with small (.25 to .5 mm) knob-like projections that were not seen in capsules adjacent to smooth-surfaced implants. A variety of foreign materials also were observed either within or adjacent to the capsules, and included droplets of liquid silicone, irregular solid fragments of the bag envelope, geometric crystalline fragments of polyurethane, and talc. Thus, the microanatomic features of periprosthetic breast capsules reflect the composition and surface configuration of the corresponding silicone bag type.

Adult↗

PubMed1985

Reduced capsule formation around soft silicone rubber prostheses coated with solid collagen.

Silicone rubber miniprostheses were coated with solid collagen formed from a fibrillar collagen suspension (Zyderm collagen implant) and then implanted subcutaneously in rats. There was a reduced amount of capsule formation around the coated prostheses, whereas the uncoated control implants all became surrounded by normal capsule. At the interface between the collagen coating and the surrounding tissue, no capsule formation was seen. At the interface between the prosthesis and the collagen coating, no capsule or only slight, locally limited, capsule formation was seen. Furthermore, capsule associated with coated implants was measurably thinner than that around control implants. When capsule appeared around coated implants, it was frequently associated with defects in the continuity of the coating. Host cells, fibroblasts, and round cells progressively invaded the coatings from the periphery inward, frequently along defects in the coating. The difference between coated and control implants became less pronounced between 60 and 120 days after implantation, as the amount of intact coating decreased. This work supports the hypotheses that the collagen coatings, while intact, prevent capsule formation, that the coatings produced by the present method are imperfect and are broken down with time, and that the disappearance of the coatings results in subsequent capsule formation. These hypotheses permit the deduction that development of better, more persistent coatings will permit indefinitely prolonged inhibition of capsule formation.

Animals↗

PubMed1990

The effects of prior exposure to silicone on capsule formation, histology, and pressure.

Investigations into the effects of prior silicone exposure on subsequent capsule formation around silicone implants assume particular relevance in light of the exponential increase in the medical application of polymers such as silicone. The inert nature of silicone has been in question with regard to its effects on the immune system, specifically whether or not it may act as a hapten or antigen. The present study analyzes the effects of prior silicone exposure on subsequent capsule formation, histological consistency, and pressures when an animal is reexposed to a silicone implant. Twelve female Lewis rats (body weight 250 g) were randomly divided into two groups. Group 1 (n = 6) rats were subcutaneously injected with 2.5 ml of Freund's Complete Adjuvant, Group 2 (n = 6) rats were injected with an equal volume of adjuvant sonicated with silicone gel. At 4 weeks a gel-filled silicone implant was placed subcutaneously in each animal. Capsule pressures were obtained at 4 months and the capsules from 3 rats from Group 2 were excised and examined microscopically. Pressures were measured again at 8 months and all remaining capsules were excised and examined. No statistically significant differences were noted when comparing two profiles over time between silicone-exposed and nonexposed animals in regard to capsule thickness or capsule pressure. However, capsule pressures were significantly lower at 8 months than at 4 months in both groups (p less than 0.034). In this model, significant reductions in capsule pressure were noted in both groups over time, but prior exposure to silicone did not appear to alter capsule histology, thickness, or pressure.

Animals↗

PubMed1997

Migration of silicone through the fibrous capsules of mammary prostheses.

The usual reaction of the human body to implantation of a silicone prosthesis is formation of a fibrous capsule. Local reactions to silicone outside this fibrous capsule and distant migration of silicone particles have been described. So far, transcapsular migration of silicone particles from the mammary implant through the fibrous capsule of mammary prostheses has not been studied. In this prospective study 71 capsules found in 40 patients were histologically studied. The chi-squared test was applied to evaluate a possible correlation between silicone migration on the one hand and implant age and integrity of the prostheses on the other. The degree of silicone migration was discerned in four stages. Stage 1 represents no silicone particles in the capsule, stage 2 represents migration up to less than half of the capsule thickness, stage 3 shows migration confined to the outer half of the capsule thickness, and stage 4 means transcapsular silicone migration. In only 4 of 71 capsules no migration into or through the capsule was observed. The degree of silicone migration was significantly less in patients in whom the capsule was calcified and was significantly more in patients in whom implantation exceeded 12 years. There was no significant correlation between the status of the prosthesis (intact, bleeding, or ruptured) and the degree of silicone migration.

Adult↗