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PubMed2001

Magnetic resonance imaging of injected silicone: findings in seven male-to-female transsexuals.

Our goal was to describe the MR findings of subcutaneously injected silicone in male-to-female transsexuals and to determine the most optimal combination of pulse sequences for discrimination of injected silicone from the surrounding structures. Seven male-to-female transsexuals were referred for MRI in order to detect the injected silicone in the subcutaneous tissues and to visualize distant migration and possible complications. Conventional spin-echo (SE) T1-weighted and turbo SE proton-density/T2-weighted, plain short tau inversion recovery (STIR), and two STIR sequences with, respectively, water and silicone suppression were applied at 1.5 T. Three observers trained in MRI analysed the images separately for the abnormalities and rated the images using a four-level scale. The STIR with water suppression provided the highest contrast between silicone and the surrounding adipose tissue. Silicone-specific STIR pulse sequences provided clear images for the evaluation of the amount and patterns of local and distant spread of injected fluid silicone. Magnetic resonance imaging readily identifies the subcutaneously injected silicone, its distant migration and the amount of tissue disorganization around the silicone deposits. Two silicone-specific STIR sequences are usually sufficient for imaging the spread of silicone.

Adult↗
PubMed1998

Silicone oil tamponade to seal macular holes without position restrictions.

OBJECTIVE: The authors performed a study to determine the effectiveness and safety of silicone oil as a substitute for gas to fill the vitreous cavity to treat macular holes. DESIGN: Multicenter, nonrandomized, interventional trial. PARTICIPANTS: Thirty-seven consecutive patients chose vitrectomy with silicone tamponade instead of gas to treat 40 eyes with stage-2 to stage-4 idiopathic age-related macular holes. Stage-2 holes constituted 40% of the holes, and stage-3 and stage-4 holes made up 60%. INTERVENTION: All eyes were treated with vitrectomy, manual detachment of the posterior vitreous face (not done for stage-4 holes), autologous serum instillation, and silicone fill of the vitreous cavity. After insertion of the oil, the patients resumed normal activity with no restriction of head or eye position except to avoid faceup position. The oil was removed after approximately 6 weeks. MAIN OUTCOME MEASURES: The authors considered the seal of the macular hole and the preoperative and postoperative logarithm of the minimum angle of resolution (logMAR) visions the most significant measures for comparison to other studies. RESULTS: Eighty percent of all holes and 86% of holes not treated previously were sealed with a single silicone tamponade of the vitreous cavity. The logMAR value of visual acuity improved an average of 0.26 (2.6 lines) to 0.61 (20/81) for all eyes and 0.34 (3.4 lines) to 0.52 (20/66) when the macular hole sealed. Completeness of fill of the vitreous cavity with silicone affected seal of the macular hole. Three of eight eyes in which open holes developed after oil removal had less than 90% fill of the vitreous cavity by silicone. Sixty-nine percent of lenses increased opacity one grade or were removed after silicone tamponade. There were no significant adverse effects arising from silicone tamponade. CONCLUSIONS: Silicone oil tamponade of macular holes is effective and safe. Silicone may be optimal for the treatment of macular holes in persons who must travel, who cannot maintain facedown positioning, or who have monocular vision. The most important factor in the successful closure of the macular hole was the completeness of fill of the vitreous cavity with silicone oil.

Adult↗
PubMed1985

Silicone synovitis of the wrist.

Foreign body giant cell synovitis and focal bony destruction requiring secondary surgery developed in nine patients after carpal and radiocarpal arthroplasty with silicone rubber implants. Synovitis followed silicone rubber replacement of the lunate in four patients, the carpal scaphoid in two patients, and the trapezium in one patient, trapezial resurfacing hemiarthroplasty in one patient, and total wrist arthroplasty in one patient. All the removed implants were deformed. Some had changed in color from clear white at the time of insertion to yellow-white or deep yellow upon removal. Scanning electron microscopy of a silicone rubber implant of the lunate removed from one patient revealed extensive fibrillation in the capitate fossa. Light microscopy of the synovium revealed hyperplasia and hundreds of fragments of silicone particulate debris throughout the tissue adjacent to the implant. The silicone debris was surrounded by multinuclear foreign body giant cells in the eight patients from whom the synovium was studied. All patients required revision surgery. We believe that in the patients studied, synovitis represented a biologic reaction to the silicone fragments found scattered throughout the synovium for the following reasons: The synovitis found was not present before surgery (except in the patient with rheumatoid arthritis); the synovitis found was not associated with the condition for which replacement arthroplasty was performed (except in the patient with rheumatoid arthritis); synovitis subsided after implants were removed; and synovitis was noted histologically in areas of silicone debris and appeared directly related to silicone seeding. Fibrillation, fragmentation, and local seeding of silicone after carpal or radiocarpal arthroplasty appear related to gradual deformation of the implant, which was the result of repeated compressive loading and shearing. Clinically significant complications of rubber carpal or radiocarpal arthroplasty with silicone rubber implants may develop from silicone synovitis.

Adolescent↗
PubMed1998

Duration of ovulation suppression with subcutaneous silicone implants containing norgestomet in Bos indicus heifers and cows.

The aim of this study is to determine the duration of suppressing oestrus or ovulation in Bos indicus heifers and cows using norgestomet (N) incorporated into a silicone implant. Twelve heifers and 18 cows undergoing oestrous cycles were allocated to one of two treatment groups (6 heifers and 9 cows per group). Animals were treated with a single subcutaneous (s.c.) silicone implant containing 3 mg of N or two identical silicone implants (6 mg of N in two silicone implants) on day 0 of the study. An analogue of prostaglandin F2-alpha was administered intramuscularly, to all animals on days 0 and 6 to induce regression of corpora lutea. Implants were removed from all animals on day 21. Animals were observed for signs of behavioural oestrus while implants were in situ and for 6 d following implant removal. Blood samples were collected on alternate days from day 0 to 20 and again on day 21 and analysed for plasma progesterone (P4). Transrectal ultrasonography was performed on days 0, 6, 10, 14, 18, 21, 24, 26,27, and along with concentration of P4 in plasma was used to confirm ovulation during the treatment period. The cumulative percentages of animals ovulating during the 21 days implants were in situ were 6.7% (3 mg of N in one silicone implant) and 0% (6 mg of N in two silicone implants)Intervals from implant removal to oestrus (mean +/- S.E.M.) did not differ significantly among animals treated with either 3 or 6 mg of N in silicone implants (46.8 +/- 7.0 vs. 55.4 +/- 7.1 h, P = 0.398). Variances in interval from implant removal to oestrus among animals treated with 3 or 6 mg of N in silicone implants were also homogeneous (P = 0.942). The mean diameter of the ovulatory follicle on day 21 was larger in the animals treated with 3 mg of N compared to animals treated with 6 mg of N in two silicone implants ( 13.1 +/- 0.8 vs. 9.7 +/- 0.7 mm, P = 0.005). We conclude that treatment with 3 mg of N in a silicone implant will suppress ovulation in Bos indicus heifers and most cows for 21 d. Six mg of N in two silicone implants will suppress ovulation for 21 d in both cows and heifers.

Animals↗
PubMed2006

A silicon transporter in rice.

Silicon is beneficial to plant growth and helps plants to overcome abiotic and biotic stresses by preventing lodging (falling over) and increasing resistance to pests and diseases, as well as other stresses. Silicon is essential for high and sustainable production of rice, but the molecular mechanism responsible for the uptake of silicon is unknown. Here we describe the Low silicon rice 1 (Lsi1) gene, which controls silicon accumulation in rice, a typical silicon-accumulating plant. This gene belongs to the aquaporin family and is constitutively expressed in the roots. Lsi1 is localized on the plasma membrane of the distal side of both exodermis and endodermis cells, where casparian strips are located. Suppression of Lsi1 expression resulted in reduced silicon uptake. Furthermore, expression of Lsi1 in Xenopus oocytes showed transport activity for silicon only. The identification of a silicon transporter provides both an insight into the silicon uptake system in plants, and a new strategy for producing crops with high resistance to multiple stresses by genetic modification of the root's silicon uptake capacity.

Amino Acid Sequence↗
PubMed2001

Silicone oil used in microdrop culture can affect bovine embryonic development and freezability.

The effect of silicone and paraffin oil, which is routinely used to overlay in vitro embryo culture media, on bovine in vitro embryonic development and on their subsequent survival after one-step vitrification was investigated. In experiment 1, silicone oil batch 13 was compared with paraffin oil. Embryonic development to the eight-cell and blastocyst stage was significantly impaired by silicone oil batch 13 in comparison with paraffin oil (p < 0.0001). Normal looking blastocysts produced under both types of oil were vitrified. None of the blastocysts that were produced under silicone oil batch 13 survived the vitrification procedure whereas 59% of the blastocysts survived when they were cultured under paraffin oil both before vitrification and after warming. In experiment 2, another batch no. 7 of the same brand of silicone oil was compared with paraffin oil. No effect of the type of oil on embryonic development until the eight-cell stage could be demonstrated. However, the blastocyst formation rate was significantly lower with silicone oil batch 7 than with paraffin oil. The survival of vitrified blastocysts after warming was significantly improved when silicone batch 13 was replaced by batch 7 (0 and 41%, respectively) although it was still lower when compared with the survival of blastocysts developed under paraffin oil (53%) (p < 0.05). In further attempts to find the cause of the problem, the silicone and paraffin oils were analysed for Zn-contents (experiment 3). Zn-contents were comparable for silicone oil batch 13 (0.87 microM), silicone oil batch 7 (0.62 microM) and paraffin oil (0.73 microM). Media, conditioned by bovine oviduct epithelial cells cultured with a silicone or paraffin oil overlay were analysed by means of thin layer chromatography for differences in qualitative fatty acid composition. It was possible to detect that oil overlay changed the relative abundance of fatty acids in the different lipid classes. In the free fatty acid fraction, it was skewed in favour of palmitic acid and in cholesterol esters and phospholipids in favour of linoleic acid. It appears that due to the changed lipid contents of the medium, embryonic membranes are rendered more susceptible to freezing due to altered membrane composition or by membrane damage caused by lipid peroxidation.

Animals↗
PubMed1998

Silicone elastomer cerebrospinal fluid shunt systems. Council on Scientific Affairs, American Medical Association.

A 1995 resolution of the American Medical Association House of Delegates, introduced by the American Academy of Neurology, the American Association of Neurological Surgeons, and the Congress of Neurological Surgeons, asked the American Medical Association Council on Scientific Affairs to add the use of hardened silicone shunts to its study of the effects of silicone gel used in breast implants. On consideration of the important differences between the two materials, silicone elastomer ("hardened silicone") and silicone gel, the Council on Scientific Affairs elected to address the subject of silicone elastomer shunt systems separately. This report describes the different types of medical-grade silicone used in medical devices, the incidence of hydrocephalus and its causes and treatment, and the use of cerebrospinal fluid shunt systems made of silicone elastomer. Published case reports of possible immunological disease in patients who have had silicone elastomer cerebrospinal fluid shunt systems implanted are reviewed. The Council on Scientific Affairs concluded that the evidence presented does not support the occurrence of immune-mediated systemic reactions to implanted silicone elastomer cerebrospinal fluid shunt systems. The local granulomatous or inflammatory responses observed in some patients with silicone shunt systems have not been shown to be immunologically mediated; similar reactions have been described with other implanted foreign bodies.

Cerebrospinal Fluid Shunts↗
PubMed1992

Problems and timing in the removal of silicone oil.

The risk associated with silicone oil removal after complex vitreoretinal surgery is unclear. Therefore, a cohort of 87 consecutive cases of silicone oil removal were analyzed. Eyes with attached retina before silicone oil removal with a follow-up of at least 5 months were included into the study. Forty-eight eyes had severe proliferative diabetic retinopathy; 39 eyes had complex proliferative vitreoretinopathy or giant retinal tears after trauma. Additional clinical features included the presence of a secondary cataract or secondary glaucoma in some eyes. The rate of postoperative complications was different in the two groups: 75% of proliferative diabetic retinopathy patients remained attached; of proliferative vitreoretinopathy patients, only 48.5% remained stable. Whereas success was independent of the duration of intraocular silicone oil tamponade in proliferative diabetic retinopathy, removal of silicone oil was more successful in cases of proliferative vitreoretinopathy in which there was a longer period of silicone oil tamponade. Complications occurring usually were severe and led to a loss of visual acuity. The removal of silicone oil from eyes with secondary glaucoma resulted in an improvement in 68% of patients. The rate of vitreoretinal complications after silicone oil removal, even in cases with a clinically stable-appearing retina, is rather high. Silicone oil removal therefore has to be considered a procedure posing new and ill-defined risks, especially if the indications for the use of silicone oil as an internal tamponade are rather strict. Exact criteria for the timing and safe removal of silicone oil in these complex vitreoretinal disorders still need to be defined.

Adult↗
PubMed2006

Silicone allergy: A new cause for cochlear implant extrusion and its management.

OBJECTIVE: We introduce silicone allergy as a rare cause for cochlear implant extrusion and discuss its management. STUDY DESIGN: Retrospective case series and literature review. SETTING: Tertiary referral centers. PATIENTS: Primary eligibility criteria included patients who experienced a delayed extrusion of their cochlear implants with negative wound cultures and had a suspected or a test-proven allergy to silicone components of an implant. INTERVENTIONS: Silicone allergy testing, explantation of a cochlear implant containing allergenic silicone materials, reimplantation with a custom-made cochlear implant excluding an allergenic silicone component. OUTCOME MEASURES: Uneventful wound healing and extrusion-free long-term follow-up after the reimplantation with a custom-made cochlear implant excluding an allergenic silicone component. RESULTS: Three known cases of cochlear implant extrusion as a result of silicone allergy have been noted from 1991 through 2004 in three cochlear implant programs in the United States. All three devices extruded, resulting in explantation of the old device and reimplantation with a new custom-made device eliminating the allergenic silicone component. Wound cultures were negative in all cases. All three patients experienced a delayed extrusion of their devices. Two of these patients had a test-proven allergy to the implant's silicone components, whereas the third patient was presumed to have a hypersensitivity solely on the basis of a clinical presentation. CONCLUSION: We propose that silicone allergy is a rare cause of cochlear implant extrusion. Patients experiencing cochlear implant extrusion, particularly with a delayed onset and negative wound culture results, should be tested for silicone allergy.

Child, Preschool↗
PubMed1990

Effect of silicone oil on protein adsorption to hydroxyapatite in vitro and on pellicle formation in vivo.

Silicone oil has been introduced in a dentifrice for smokers because of its effect as a polishing agent. Silicone oils are hydrophobic in character and have low surface tensions and good wetting properties. Due to the low surface tension, silicone oils may spread readily on solid surfaces and cover them with a thin, water-repellent film. Introduced via dentifrices silicone oil may thus well be able to adsorb to enamel surfaces and to interfere with surface characteristics such as protein adsorption. The aim of the present study was to examine the effect of silicone oil on protein adsorption to hydroxyapatite (HA) in vitro and on pellicle formation in vivo. The effect on protein adsorption to HA in vitro was studied by adsorption of albumin to either untreated or silicone oil treated HA powders. Ion exchange chromatography was also used with either untreated or silicone oil treated HA as bed materials. The effect on pellicle formation in vivo was studied using enamel fragments carried in the mouth to acquire pellicle material. The chemical composition of the acquired pellicle was studied by collection and chemical analysis of pellicle material formed on enamel surfaces in vivo. The study showed that silicone oil treated HA took up less protein and that the adsorbed protein was bound to hydroxyapatite by a different mechanism as compared to untreated controls. The results indicated that hydrophobic interactions could be involved in binding of proteins to silicone oil treated hydroxyapatite. Silicone oil treated enamel fragments carried in the mouth showed a slower rate of pellicle formation as compared to untreated fragments. The amino acid composition of the acquired pellicle collected in vivo from silicone oil treated enamel surfaces was also different from pellicle material collected from untreated enamel.

Adsorption↗
PubMed2006

Immunopathology of intraocular silicone oil: enucleated eyes.

AIMS: To characterise the distribution of silicone oil in ocular tissues in globes enucleated after complicated retinal detachment, and to document the distribution and nature of any associated inflammatory response. METHOD: 9 enucleated globes that had previously undergone retinal detachment surgery with silicone oil and 7 control globes that had undergone enucleation after retinal detachment surgery (n = 2) or ocular trauma (n = 5) were studied. Sections were histologically examined using light microscopy to document the distribution of silicone oil in ocular tissues. Immunohistochemical analysis was carried out using the ABC technique and a panel of monoclonal and polyclonal antibodies. Electron microscopy was undertaken to observe the penetration of silicone oil in the trabecular meshwork of the anterior chamber drainage angle. RESULTS: Silicone oil was distributed throughout the globes-notably in the iris, ciliary body, retina, trabecular meshwork and epiretinal membranes. Focal areas of intraretinal silicone were associated with disorganised retinal architecture, retinectomy sites or subretinal oil. The distribution of macrophages was closely related to the distribution of silicone oil. T and B lymphocytes were not associated with silicone oil unless additional pathology was also present-for example, cyclitic membrane or uveitis. One of the nine eyes had silicone oil present in the optic nerve. In the control globes, the inflammatory response was mediated primarily by macrophages and T lymphocytes, and was less marked than that observed in the silicone oil globes. CONCLUSION: This study shows that silicone oil may be sequestered in varied ocular tissues and is associated with localised inflammation mediated by macrophages.

Adolescent↗
PubMed2001

Retinal redetachment after removal of intraocular silicone oil tamponade.

AIM: To evaluate frequency and risk factors of retinal redetachment after removal of intraocular silicone oil tamponade. METHODS: The study included 225 patients who consecutively underwent intraocular silicone oil removal at a mean interval of 10 months after pars plana vitrectomy had been performed by one of two surgeons. Mean follow up time was 17.37 (SD 14.40) months (range 3.02-67.42 months). RESULTS: In 57 of 225 (25.3%) patients, the retina detached after removal of silicone oil. Risk factors for retinal redetachment were the following: number of previously unsuccessful retinal detachment surgeries (p=0.0008); surgeon (p=0.007); visual acuity before silicone oil removal (p=0.009); incomplete removal of vitreous base (p=0.01); absence of an encircling band in eyes with proliferate vitreoretinopathy in which an inferior retinotomy had not been performed (p=0.01); and indication for pars plana vitrectomy. Rate of retinal redetachment was statistically (p>0.05) independent of the technique of silicone oil removal and duration of silicone oil endotamponade. CONCLUSION: Retinal redetachment after removal of silicone oil endotamponade can occur in approximately a fourth of patients, depending on the criteria to use and to remove silicone oil. Risk factors for recurrent detachment included the following: number of previously unsuccessful retinal detachment surgeries, surgeon, preoperative visual acuity, incomplete removal of the vitreous base, absence of an encircling band, and reason for pars plana vitrectomy. The rate of retinal redetachment is independent of the technique of silicone oil removal and duration of silicone oil endotamponade, with a minimal duration of silicone oil tamponade of about 3 months in the present study.

Adolescent↗
PubMed1996

Silicone gel-filled breast implants in women: findings at H-1 MR spectroscopy.

PURPOSE: To evaluate, at hydrogen-1 magnetic resonance (MR) spectroscopy, the effect of implantation time, implant status, and implant removal on the amount of silicone in the liver in women with silicone gel-filled breast prostheses. MATERIALS AND METHODS: The study population included 55 women (39 patients with silicone gel-filled prostheses and seven from whom implants had been removed, and nine control subjects [eight with no implant and one with saline-filled implants]). Stimulated-echo acquisition mode, or STEAM, H-1 MR spectroscopy was performed to determine the concentration of silicone in the liver. Implant status at the time of spectroscopy was diagnosed at MR imaging. RESULTS: Twenty of 39 (51%) women with implants had ruptured prostheses. Resonances associated with the presence of silicone and partially hydrolyzed silicone (0.3 to -0.8 ppm with respect to water at 4.7 ppm) and other resonances that are not yet assigned (-2 to -5 ppm) were detected in 27 (69%) of the 39 women (17 with ruptured implants). Relative signal intensities of the silicone species detected in the liver in these women were found to vary substantially and were not correlated with the status of the implants (P > .70). Silicone resonances were not detected in the livers in the nine control subjects. After implant removal, no resonances between 0.3 and -0.8 ppm were observed in six of seven women, but silicone-related peaks were still detectable in the region of -2 to -5 ppm. CONCLUSION: Proton MR spectra obtained in the liver of women with silicone gel-filled breast implants helped measure silicone exposure.

Adult↗
PubMed2006

Comparison of silicon oil removal with various viscosities after complex retinal detachment surgery.

BACKGROUND: Despite the progress in vitreoretinal surgery and the importance of silicone oil as an adjunct for the treatment of complex forms of retinal detachment, controversy still surrounds the issue of selecting the proper oil viscosity for clinical use. Herein, we evaluate the outcomes of retinal detachment (RD) surgery after removing silicone oils of different viscosities. METHODS: In this retrospective cohort study, eighty-two eyes with surgically re-attached retinas, of which 53 were filled with 5000 cs silicone oil and 29 with 1000 cs silicone oil were enrolled. We evaluated the outcomes and complications following silicone oil removal. Final anatomic success (stable re-attachment), final visual acuity (VA) and intraocular pressure (IOP)were recorded and analysed. RESULTS: Of 82 eyes, 41 had proliferative vitreoretinopathy (PVR), 24 were associated with intraocular foreign bodies, 10 had endophthalmitis and 7 had proliferative diabetic retinopathy with tractional retinal detachment. Prior to silicone oil removal, the retina was attached in all eyes, 29% had VA > or = 6/120 and 52% had IOP > or = 21 mmHg. After silicone oil removal, the retina remained attached in 59(72%) of the eyes, 34% had VA > or = 6/120 and 9% had IOP > or = 21 mmHg. Comparing 1000 cs and 5000 cs silicone oil filled eyes, redetachment occurred more frequently in the latter group especially in cases with associated PVR. Final VA worse than 6/120 was associated with initial VA < 6/120 (OR = 32.2 95%CI 7.4-140.2) and use of 5000 cs silicone oil (OR = 7.9 95%CI 1.9-32.2). No factor was significantly associated with final IOP > or = 21 mmHg. CONCLUSION: In complicated retinal detachment surgery, use of 5000 cs silicone oil may be associated with a poorer anatomic and visual outcome compared with 1000 cs silicone oil. However there was no difference between the two viscosities in IOP elevation. A randomized controlled study is necessary to further evaluate such a possibility.

Cohort Studies↗
PubMed2003

Dietary silicon intake is positively associated with bone mineral density in men and premenopausal women of the Framingham Offspring cohort.

UNLABELLED: The role of dietary silicon in bone health in humans is not known. In a cross-sectional, population-based study (2847 participants), associations between dietary silicon intake and BMD were investigated. Dietary silicon correlated positively and significantly with BMD at all hip sites in men and premenopausal women, but not in postmenopausal women, suggesting that increased silicon intake is associated with increased cortical BMD in these populations. INTRODUCTION: Osteoporosis is a burgeoning health and economic issue. Agents that promote bone formation are widely sought. Animal and cellular data suggest that the orthosilicate anion (i.e., dietary silicon) is involved in bone formation. The intake of silicon (Si, approximately 30 mg/day) is among the highest for trace elements in humans, but its contribution to bone health is not known. MATERIALS AND METHODS: In a cross-sectional, population-based study, we examined the association between silicon intake and bone mineral density (BMD) in 1251 men and 1596 pre- and postmenopausal women in the Framingham Offspring cohort (age, 30-87 years) at four hip sites and lumbar spine, adjusting for all potential confounding factors known to influence BMD and nutrient intake. RESULTS: Silicon intake correlated positively with adjusted BMD at four hip sites in men and premenopausal women, but not in postmenopausal women. No significant association was observed at the lumbar spine in any group. Categorical analysis by Si intake, or energy-adjusted Si intake, supported these findings, and showed large differences in BMD (up to 10%) between the highest (> 40 mg Si/day) and lowest (< 14 mg Si/day) quintiles of silicon intake. A significant association at the lumbar spine in men was also observed. Further analyses indicated that some of the effects seen for moderate consumption of alcoholic beverages on BMD might be attributed to Si intake. CONCLUSIONS: These findings suggest that higher dietary silicon intake in men and younger women may have salutary effects on skeletal health, especially cortical bone health, that has not been previously recognized. Confirmation of these results is being sought in a longitudinal study and by assessment of the influence of silicon intake on bone markers in this cohort.

Adult↗
PubMed2002

Dietary silicon and arginine affect mineral element composition of rat femur and vertebra.

Both arginine and silicon affect collagen formation and bone mineralization. Thus, an experiment was designed to determine if dietary arginine would alter the effect of dietary silicon on bone mineralization and vice versa. Male weanling Sprague-Dawley rats were assigned to groups of 12 in a 2 x 2 factorially arranged experiment. Supplemented to a ground corn/casein basal diet containing 2.3 microg Si/g and adequate arginine were silicon as sodium metasilicate at 0 or 35 microg/g diet and arginine at 0 or 5 mg/g diet. The rats were fed ad libitum deionized water and their respective diets for 8 wk. Body weight, liver weight/body weight ratio, and plasma silicon were decreased, and plasma alkaline phosphatase activity was increased by silicon deprivation. Silicon deprivation also decreased femoral calcium, copper, potassium, and zinc concentrations, but increased the femoral manganese concentration. Arginine supplementation decreased femoral molybdenum concentration but increased the femoral manganese concentration. Vertebral concentrations of phosphorus, sodium, potassium, copper, manganese, and zinc were decreased by silicon deprivation. Arginine supplementation increased vertebral concentrations of sodium, potassium, manganese, zinc, and iron. The arginine effects were more marked in the silicon-deprived animals, especially in the vertebra. Germanium concentrations of the femur and vertebra were affected by an interaction between silicon and arginine; the concentrations were decreased by silicon deprivation in those animals not fed supplemental arginine. The change in germanium is consistent with a previous finding by us suggesting that this element may be physiologically important, especially as related to bone DNA concentrations. The femoral and vertebral mineral findings support the contention that silicon has a physiological role in bone formation and that arginine intake can affect that role.

Administration, Oral↗
PubMed2002

MR imaging of extracapsular silicone from breast implants: diagnostic pitfalls.

OBJECTIVE: We sought to identify pitfalls in recognition of extracapsular silicone on MR imaging. MATERIALS AND METHODS: Three experienced observers reviewed MR images from 359 women with current (n = 320), prior (n = 15), or both current and prior (n = 24) silicone gel implants. Axial and sagittal fast spin-echo T2-weighted images with water suppression, axial inversion-recovery T2-weighted images with water suppression, and axial T2-weighted images with silicone suppression were obtained in a dedicated phased array breast coil on a 1.5-T magnet. Images were reviewed again when only one observer saw extracapsular silicone, and reasons for disagreement were recorded. RESULTS: Rupture was identified in 265 women (77%) with current silicone implants and 378 (55%) of 687 implants. Observers agreed in describing extracapsular silicone in 85 (12%) of 687 breasts with current silicone gel implants, of which 81 (95%) showed definite evidence of rupture on MR imaging. One observer reported extracapsular silicone in another 79 breasts. Confusion over contour deformity due to weakening versus breach of the capsule accounted for 33 (42%) of 79 disagreements. Another 20 (25%) of the 79 disagreements were attributed to poor conspicuity of extracapsular silicone on fast spin-echo T2-weighted images combined with intermittent observer failure to review inversion-recovery images. Subtlety of findings (n = 17, 22%) and technical issues (n = 9, 11%) with failed water suppression of pleural effusion or cysts and ghosting artifacts accounted for remaining disagreements. CONCLUSION: Extracapsular rupture is usually manifest as local spread of silicone in the breast and is not well-depicted on fast spin-echo T2-weighted images. Water-suppressed inversion-recovery T2-weighted images are often needed to identify extracapsular silicone. Distinction of the bulge in the fibrous capsule from herniation through the capsule remains problematic.

Adult↗
PubMedDate not supplied

Immune functional impairment in patients with clinical abnormalities and silicone breast implants.

Silicone, previously thought to be a biologically inert and harmless material, has now been reported to elicit antibody response and to be responsible for adjuvant disease in humans. The present study was designed to evaluate the immune function of forty individuals who had undergone silicone breast augmentation for a period of longer than ten years and who were compared with 40 sex and age-matched controls. The following immunological functions were studied: lymphocyte subset analysis, lymphocyte mitogenic response, NK cytotoxic activity and markers for autoimmunity such as ANA, rheumatoid factor immune complexes such as smooth muscle, myelin, and thyroid, and tissue antibodies. Results of lymphocyte subpopulation analysis showed significantly elevated T helper/suppressor ratio in 60% and significantly decreased T helper/suppressor ratio in 7.5% of the silicone implant group, while the control group showed increased helper/suppressor ratio only in 10% of tested individuals and no significant decrease in the T helper/suppressor ratio. There was 20% inhibition in T cell mitogenic responses in the silicone implant group, which is significant when compared to the controls. When NK cytotoxic activity was compared between the two groups, significant inhibition in the ability of lymphocytes to kill tumor target cells was observed in the silicone implant group. This inability of target cell lysis was attributed to the demonstrated lack of granularity of NK cells from the silicone implant group. There was significant increase in: immune complexes, anti-nuclear antibodies, anti-thyroid antibodies, anti-striated muscle cell antibody, and anti-myelin basic protein antibodies. These immunological abnormalities in individuals who underwent silicone breast augmentation indicate a mechanism of tissue injury to these patients, causing autoimmune diseases or syndromes. Since autoimmunity in some other conditions is associated with abnormalities in the HLA serotyping system, and since some collagen vascular diseases have been associated with a higher incidence of the HLA serotyping system, it is recommended that HLA studies be included in future investigations of immune-mediated abnormalities associated with silicone breast augmentation. Our findings here show definite abnormalities of the T helper/suppressor ratio, increased autoimmunity, as well as increased production of immune complexes. Silicone implants have been used in cosmetic and reconstructive surgery more than 30 years (Brown et al., 1960). The gel used in the implant is produced from silicone, which is then related with methyl chloride and polymerized to form stable polydimethylsiloxane (Brown, et al., 1960). There have been a number of reports describing the occurrence of connective tissue disease in patients after the implantation of silicone.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗