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At least 955 records · Page 53Linked to original sources
PubMed1985

Temporary silicone oil tamponade in the management of retinal detachment with proliferative vitreoretinopathy.

Silicone oil was used as a temporary (four to six weeks) tamponade in conjunction with vitreous surgery in the management of 146 eyes with retinal detachment complicated by proliferative vitreoretinopathy. A success rate of 62% (90 of 146 cases) was achieved six months after the silicone was removed. Clinical complications directly related to silicone oil were rare and did not progress or develop after the removal of silicone except for opacification of the lens in phakic eyes. This occurred frequently (43 of 55 eyes) and progressed many months after the withdrawal of silicone.

Eye Diseases↗
PubMed1984

The interaction of proteins and cells with affinity ligands covalently coupled to silicon surfaces as monitored by ellipsometry.

Two methods for the chemical binding of biomolecules to silicon surfaces are described. The first method utilizes an alkyl silane and a nucleophilic reagent to join the biomolecule to the silicon surface; the second method involves crosslinking with glutaraldehyde in order to couple the biomolecule and albumin molecules, which have first been physically adsorbed. The course of binding to the silicon surface has been followed with the aid of ellipsometry. This optical measuring technique estimates the thicknesses of, e.g., organic layers, by measuring the polarization properties of a light beam before and after reflection at surfaces. The method by which the binding of a biomolecule to its corresponding affinity ligand on silicon wafers can be followed with this technique is reported. The systems studied are concanavalin A-Saccharomyces cerevisiae cells, immunoglobulin G-Staphylococcus aureus cells, and an NAD-analog-lactate dehydrogenase. With ellipsometry it was possible to assess how the incubation time and the concentration of the cells and the biomolecules added influenced the results. It was found that an increasing time of incubation and higher concentration resulted in a more complete coverage of the silicon wafer surfaces.

Bacteria↗
PubMed1994

Localized silicon distribution in supragingival calculus from Japanese monkeys (Macaca fuscata).

Using an electron-probe microanalyser, the distribution of silicon and other elements in supragingival dental calculus in domestic Japanese monkeys (Macaca fuscata) was studied. In two out of four monkeys kept in animals centres, a localized silicon distribution was found in both fracture and oral surfaces of the calculi. The silicon-rich area consisting of silicon alone resembled opal, but the areas containing silicon and other metal ions such as magnesium, aluminium, potassium and iron resembled clay minerals. In eight domestic monkeys, including the four animals described above, abundant calculus deposits were found. However, in four captured wild monkeys and in one which had been kept for less than a year at an animal centre, no dental calculus was found. There was almost no dental plaque accumulation in captured wild monkeys. It is suggested that calculus formation in Japanese monkeys is dependent on length of exposure to a commercial diet.

Animal Feed↗
PubMed1983

Effect of fluoride, silicon, and magnesium on the mineralizing capacity of an inorganic medium and stone formers urine tested by a modified in vitro method.

An in vitro mineralizing system using bovine achilles tendon developed by Thomas and Tomita (3) was modified to enable quantitative evaluation of mineralization. Using this modified method, the potential effect of various ions on the rate of calcium uptake from inorganic mineralization medium was measured. Of the elements tested, only silicon and fluoride accelerated calcium uptake, whereas magnesium had an inhibitory effect. The simultaneous presence of silicon and fluoride in the medium had a synergistic action on calcium uptake. Urine of stone formers showed high propensity to mineralize tendon collagen, but not the urine of non-stone formers. Total content, and concentration of silicon in urine of stone formers was significantly higher than in normal urine. Addition of silicon to non-stone formers urine enhanced its capacity to mineralize collagen in vitro. These results strongly suggest the possible involvement of silicon and fluoride in the genesis of urinary calculi in man.

Achilles Tendon↗
PubMed1990

A silicone gel sheet dressing containing an antimicrobial agent for split thickness donor site wounds.

Treatment of a split thickness donor site wound in 20 patients by means of a silicone gel sheet containing Ofloxacin, an antimicrobial agent, has been tested. For a comparison, each wound was divided into two parts, one for the silicone gel treatment and the other with a collagen sheet (10 cases) or an ointment-impregnated gauze (10 cases). Although Staphylococcus aureus was detected in three wounds treated with the collagen sheet, no wound treated with the silicone gel developed an infection even though the infected wound was adjacent. Results have shown that prompt epithelialisation occurred in the silicone gel-covered wounds, with little exudate and pain compared to wounds treated with either of the dressings. Although some wounds treated with the silicone gel tended to exhibit a slightly prolonged redness compared to wounds treated with an ointment-impregnated gauze, no subsequent cosmetic problem resulted.

Adolescent↗
PubMed1988

A two-compartment modification of the silicone chamber model for nerve regeneration.

In the nerve regeneration silicone chamber model, the regenerate which forms across a 10-mm gap between proximal and distal nerve stumps is a monofascicular structure with an outer perineurial-like cell sheath. Recent work has provided indications that the geometry of the regenerate within a silicone chamber can be altered by experimental modifications of the chamber matrix. In the present study we modified the standard silicone chamber into a two-compartment chamber by inserting a 6- or 10-mm-long siliconized nitrocellulose strip in order to obtain two separate regenerates. Light microscopy 16 days after implantation revealed that two separate nerve structures had formed, one on each side of the nitrocellulose partition and adjacent to it, and each with its own perineurial-like cell sheath. In chambers with 6-mm-long strips a monofascicular regenerate started from the proximal stump and divided into two separate structures as it approached the proximal end of the strip: the two fascicles joined again into a monofascicular structure in the distal portion of the chambers. The new two-compartment silicone chamber model appears suitable for future examinations of experimental fasciculation. In addition, the nitrocellulose partition should allow one to study specific effects of growth factors on axonal regeneration in vivo, as growth factors bind strongly to untreated nitrocellulose while retaining their biological activity.

Animals↗
PubMed1985

A comparison of the physical properties of a room temperature vulcanizing silicone modified and unmodified.

RTV silicone MDX 4-4210 unmodified and modified with the addition of 5%, 10%, and 15% 360 MF 100cs was tested for the following physical properties: tensile strength, ultimate elongation (ASTM D412 die C), tear resistance (ASTM D624, die C), and Shore A Durometer hardness (ASTM D2240). The initial mechanical properties of unmodified RTV silicone were superior to those of RTV silicone modified with 5%, 10%, and 15% 360 MF except for hardness. The value for each property measured was found to decrease linearly with the amount of 360 MF added. If additional softness is desired, it can be achieved with the addition of 360 MF to RTV silicone at the expense of decreased strength, elongation, and tear resistance. Even with the addition of 15% 360 MF the values for tear resistance and elongation were in the standard range. The tensile strength of unmodified RTV silicone fell below the accepted values.

Chemical Phenomena↗
PubMed1987

Destructive lesions of the mandibular condyle following diskectomy with temporary silicone implant.

Dacron-reinforced silicone is widely used as disk-replacement implant material in the temporomandibular joint. A retrospective radiographic analysis was undertaken in a series of thirty-two patients on whom diskectomy had been performed. Twenty patients had received temporary silicone implants, whereas twelve patients had surgery without disk-replacement implants. Six of the patients with implants had destructive lesions of the mandibular condyles at follow-up examinations, but no such lesions were seen in any of the patients who had surgery without implants. Histologic analysis of material removed from one patient who had a second operation showed multiple particles of foreign material surrounded by focally marked inflammatory reaction with foreign body granulomas. The underlying cartilage and bone showed focal resorption and bone destruction. Electron microscopy combined with energy-dispersive x-ray microanalysis showed that the foreign material contained silicone. It was concluded that the radiographically observed destructive lesions of the mandibular condyle may be a sign of a reactive synovitis induced by silicone particles abraded from the silicone implant.

Adult↗
PubMed1988

Distribution of silicones in water, sediment and fish in Japanese rivers.

A new analytical method for assaying polyorganosiloxanes (silicones) in environmental samples is presented. The method utilizes petroleum for solvent extraction of the sample (water, sediment, biological tissue) together with inductively coupled plasma detection of the extracted organic silicones. The detection limit for silicones in the final methyl isobutyl ketone sample/extract is approximately 0.01 ppm, and the method is applied to samples from various Japanese rivers to quantify silicones in several environmental materials. Silicones are reported from river waters (up to approximately 50 ppb), riverine sediments (up to 6 ppm), and as an extractable component of fish tissue (up to approximately 0.9 ppm).

Animals↗
PubMed1994

A profile of symptomatic patients with silicone breast implants: a Sjögrens-like syndrome.

Exposure of breast tissue to silicone has been associated with autoimmune diseases in the medical literature since the 1960's. Japanese women injected with raw silicone had features of a collagen vascular disease but did not meet criteria for a specific diagnosis. Subsequently, we have seen women with silicone breast implants that have similar problems. We performed a prospective noncontrolled study on women with silicone breast implants. Results from the first 50 consecutive women revealed the most prominent complaints in this group were fatigue (89%), generalized stiffness (75%), poor sleep (71%), and arthralgias (78%). Other problems included Raynaud's phenomenon, alopecia, adenopathy, night sweats, and frequent sore throats. Unexpectedly, half of these women complained of dry eyes and dry mouths. Positive antinuclear antibodies and or rheumatoid factors were discovered in 38% of patients although the anti-SSA antibody was found in only one patient and anti-SSB in none. Labial salivary gland biopsies in 5 cases showed mononuclear cell infiltrates compatible with Sjögren's syndrome in 4. The infiltrating cells were predominantly CD68 positive monocyte/macrophages, which is different from what is found in Sjögren's syndrome. These findings may indicate the presence of a unique syndrome associated with silicone implants that is characterized by musculoskeletal pain and autoimmune features.

Adult↗
PubMed1995

Silicone plate-induced granuloma presenting pituitary apoplexy-like symptoms: case report.

BACKGROUND: Granuloma induced by silicone plate is rare. We present a case of silicone plate-induced granuloma in the sellar and suprasellar region confirmed by histologic examination at surgery. CASE DESCRIPTION: A 31-year-old woman suddenly complained of severe headache, polyuria, and visual disturbance 8 years and 9 months after an initial transsphenoidal surgery for pituitary adenoma. At surgery, granuloma and hematoma around the dimethylpolysiloxan (silicone) plate, which had been placed on the sella floor at the initial surgery, were found. Postoperative course was uneventful. CONCLUSIONS: Our presented case showed one of the disadvantages for silicone placement for repairing the sella floor, and the diagnostic possibility of silicone-induced granuloma in the sellar region.

Adult↗
PubMed1992

Silicone-immobilized biocatalysts effective for bioconversions in nonaqueous media.

A hydrophobic silicone polymer could be effectively applied to immobilization of two kinds of biocatalysts operating in organic media. Horse liver alcohol dehydrogenase, which was solubilized in a small amount of water, or deposited on water-filled hydrophilic particles, was immobilized in this material. This configuration of the preparation involving finely dispersed aqueous phase permitted a simple packed-bed operation for the enzymatic oxidation of alcohol and reduction of aldehyde with a coupled-substrate NAD(H) recycling in n-hexane. Another example was the immobilization of Nocardia corallina which catalysed epoxidation of liquid alkenes such as 1-tetradecene, 1-octene, and styrene in the presence of n-hexadecane. In order to adjust the hydrophobicity-hydrophilicity balance of the support, it was effective to immobilize the cells in a mixed matrix composed of silicone polymer and Ca-alginate gel. The optimum composition of the mixed matrix, which yielded the highest productivity of epoxide, was 80-90% silicone + 20-10% alginate for the production of 1,2-epoxytetradecane, 40-50% silicone + 60-50% alginate for 1,2-epoxyoctane, and almost 0% silicone + 100% alginate for styrene oxide. This significant change of the optimum composition was primarily associated with the degree of substrate inhibition.

Alcohol Dehydrogenase↗
PubMed1995

Seven surgical silicones retain Staphylococcus aureus differently in vitro.

In an in vitro study, we have quantitatively evaluated the capability of seven different types of silicone to retain a Staphylococcus aureus strain, isolated from a surgical wound. All the silicone specimens were taken from prostheses already used in plastic or ophthalmological surgery. Two polymers were used as controls: polystyrene, because of its known capability to favour in vitro bacterial recovery, and nylon, for its bacterial repellence. The results show that all silicones are suitable substrata for Staphylococcus aureus. However, there are some differences among silicone types. The amounts of bacteria retained from silicone oils are greater than or equal to those obtained from the positive control material.

Biocompatible Materials↗
PubMed1995

Downregulation of silicone-induced chronic arthritis by gastric administration of type II collagen.

We previously demonstrated that intra-articular injection of silicone in rats induced acute arthritis followed by chronic destructive joint inflammation in which T cells played a role. To investigate whether the model of T cell-mediated chronic silicone-induced arthritis (SIA) is modified by oral administration of type II collagen (CII), rats were fed CII either before or after intra-articular injection of silicone. We found that feeding CII either before or after intra-articular injection of silicone markedly suppressed the development of chronic arthritis. The early phase of acute joint inflammation was not affected by the oral antigen. There were no proliferative responses to CII of lymph node cells from rats with SIA. The proliferation to CII of lymph node cells from CII-primed rats was markedly suppressed by the addition of spleen cells from animals fed CII. Furthermore, the proliferative response to keyhole limpet hemocyanin (KLH) of KLH-sensitized lymph node cells was also suppressed by the addition of CII plus spleen cells from CII-fed animals. Injection of the spleen cells into rats followed by intra-articular injection of silicone inhibited the development of chronic SIA. These results indicate that T cell-mediated chronic arthritis may be downregulated by oral administration of CII and that the downregulation of joint inflammation may be due to the generation of CII-specific regulatory lymphocytes that react to CII abundant in cartilage.

Acute Disease↗
PubMed1996

A comparative study of silicone net dressing and paraffin gauze dressing in skin-grafted sites.

This prospective randomized study has compared paraffin gauze dressing (n = 19) with silicone net dressing (Mepitel, n = 19) applied as the first layer to newly grafted burn wounds. At the first postoperative dressing visual analogue pain scores were greater in the paraffin gauze group (mean 4.4) than in the silicone net group (mean 1.4, P < 0.01). All patients in the paraffin gauze group experienced some degree of pain on dressing removal, whereas 53 per cent of patients in the silicone net group experienced no pain. Overall graft take was similar in both groups, (silicone net mean 95.7 per cent; paraffin gauze mean 94.3 per cent). Dressings were harder to remove in the paraffin gauze group as assessed by a simple scoring system (P < 0.001). In conclusion silicone net dressing confers advantages over conventional paraffin gauze, especially in reducing patient discomfort during dressing changes.

Adolescent↗
PubMed1993

Echo-planar chemical shift imaging of silicone gel prostheses.

We have developed an echo-planar (EP) proton chemical shift imaging (CSI) MR technique that allow us to discriminate the polydimethylsiloxane (PDMS, silicone) proton MR signal from that of the fat and water protons found in tissues, in order to map the distribution of PDMA in humans who have silicone gel prostheses. Silicone gel-filled prosthetic implants induce histologic changes in the surrounding tissue which are attributed to the leakage of free PDMS from the prosthesis. The T2 relaxation measurements of three silicone gels show that there are two components in them, each with a different degree of molecular mobility. The presence of free silicone is confirmed by chloroform extraction, which removed 14-28% of the material. This free polymer present in the gel can pass through the intact or ruptured membrane of the implant into the surrounding tissue. Our preliminary imaging results indicate that EP-CSI MR might be useful as a diagnostic technique for implant malfunction.

Breast↗
PubMed2005

Biocompatibility of surfaces for antibody microarrays: design of macroporous silicon substrates.

Major efforts to develop antibody microarray technology to enable global proteome analysis to be performed in a facile manner are under way. In this process, the design and the properties of the substrate will play crucial roles. In the present study, we have developed novel, highly biocompatible solid supports for microarrays, using adsorbed recombinant human single-framework antibody fragments as probes. Several silicon-based supports, including planar silicon, micro- and macroporous silicon, and nitrocellulose-coated variants thereof, were designed and evaluated in a stepwise procedure. The surfaces were scored based on biocompatibility and probe binding capacity as judged by spot morphology, signal intensities, signal to noise ratios, dynamic range, sensitivity, and reproducibility. A set of five commercially available substrates, selected to represent a set of supports providing different surface and coupling chemistries, was used as reference surfaces. The results showed that several well-performing silicon-based supports could be designed; in particular, a nitrocellulose-coated macroporous variant, MAP3-NC7, received the highest scores. In comparison, MAP3-NC7 displayed properties equal to or better than those of the reference substrates. Taken together, designed surfaces based on silicon can undoubtedly meet the requirements of the next generation of solid supports for antibody microarrays.

Antibodies↗
PubMed2005

Morphology and adhesion of biomolecules on silicon based surfaces.

Biomolecules such as proteins, on silicon based surfaces are of extreme importance in various applications including microfabricated silicon implants, in the fabrication of microdevices with protein compounds (e.g., biosensors), and therapeutics. Morphology of silicon based surfaces with and without biomolecules and their adhesion with the substrate govern performance and reliability of the biological application. In this research, step by step morphological changes of silicon as well as adhesion during its surface modification have been studied using atomic force microscopy. To improve adhesion between biomolecules and the silicon based surfaces, chemical conjugation as well as surface patterning have been used. Changes in adhesion as a result of surface modification have been analyzed with the help of contact angle measurements. Phase imaging technique was used to confirm the presence of biomolecules on the surface. To understand the relationship between morphology and local values of adhesion, adhesion mapping and local stiffness mapping were carried out.

Cells, Cultured↗