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At least 37 records · Page 2Linked to original sources
PubMed2006

Study on the effects of nylon-chitosan-blended membranes on the spheroid-forming activity of human melanocytes.

Though reported limitedly in tissue engineering, modification of cellular functions can be achieved by culturing them into multicellular spheroids. We have shown melanocytes form spheroids on chitosan surface. However, how biomaterials promote spheroid formation has never been systemically investigated. In this work, nylon, which inhibits melanocyte spheroid formation, and chitosan, which promotes melanocyte spheroid formation, are used to prepare nylon/chitosan-blended membranes. Membranes composed of pure nylon, pure chitosan and various ratios of nylon and chitosan are employed to examine their effects on spheroid formation. Melanocytes show better adhesion to nylon membranes than that to chitosan membranes. In blended membranes, as more nylon is incorporated, cell adhesion increases and the trend for spheroid formation decreases. Melanocytes can only form spheroids on membranes with poorer cell adhesion. Examining the surface of the blended membranes shows phase separation of nylon and chitosan. As nylon content increases, the nylon phase on the membrane surface increases and thereby enhances cell adhesion. The opposite trend for cell adhesion and spheroid formation substantiates our hypothesis of spheroid formation on biomaterials: a balance between cell-substrate interaction and cell-cell interaction. The decrease in cell-substrate interaction tilts the balance to a state more favorable for spheroid formation. Our work can serve as a model to investigate the relative strengths of cell-cell and cell-substrate interactions and also pave way to design blended membranes with desired physical properties while preserving the spheroid-forming activity.

Biocompatible Materials↗
PubMed2003

Four-week inhalation toxicity study in rats with nylon respirable fibers: rapid lung clearance.

This inhalation toxicity study in rats was conducted to assess the hazard potential for workers inhaling Nylon respirable fibers. Groups of 48 male rats each were exposed, nose-only, 6h per day, 5 days per week, for 4 weeks to aerosols of uncoated, finish-free Nylon respirable-sized, fiber-shaped particulates (RFP) at concentrations of 0, 4, 15 and 57 fibers (f)/cm3. Nylon RFPs were prepared using flock rotary cutters followed by vigorous opening procedures. After exposures, the lungs of sham and Nylon-exposed rats were assessed at 1 and 8 days, and 1, 3, 6 and 12 months postexposure. The results showed that the retained mean lung burdens at 1 day postexposure were 1.75E+07 RFP/lung (high level). Mean lengths and diameters of the Nylon aerosol were 9.8 and 1.6 microm, respectively. Lung clearance of Nylon RFPs was rapid over the 12-month period. There were no significant increases in lung weights, indications of pulmonary inflammation, or alveolar macrophage functional deficits in Nylon-exposed animals versus controls based on cell differentials, bronchoalveolar lavage (BAL) fluid analyses, and macrophage phagocytosis or chemotaxis activity. Histopathology revealed no adverse lower pulmonary or upper respiratory effects. In summary, the no-observed-effect level (NOEL) for inhaled Nylon RFP was 57f/cm3 (20mg/m3), the highest concentration tested.

Administration, Inhalation↗
PubMedDate not supplied

Effect of formulation factors on the matrix pH of nylon microcapsules.

The application of nylon microencapsulation as a drug delivery system inherently demands that the microencapsulated matrix should not cause degradation of the encapsulated drug. The presence of alkaline hexamethylenediamine (HMD) in the microcapsule core will affect the final pH of the microcapsules and may influence the stability of some drugs. To follow the pH within the microcapsule core during manufacture, pH indicators were encapsulated. The final pH was found to depend on the formulation used and could be controlled by the addition of acid. Several other variables affecting the nylon wall formation were examined to determine optimum processing conditions. Increased agitation produced a decrease in microcapsule size. This cause an increase in nylon weight recovered. The increased recovery of nylon was due in part to nylon formation over a larger surface area. Varying the amounts of HMD and sebacyl chloride (SC) used also affected the total weight of nylon formed. In general, more nylon is recovered as the level of each reactant increases. However, the molar ratio of HMD:SC determined the total amount of nylon formed when SC was present in excess.

Alginates↗
PubMed1981

Amphotericin-B promotes leukocyte aggregation of nylon-wool-fiber-treated polymorphonuclear leukocytes.

Severe pulmonary reactions have been reported in patients receiving leukocyte transfusion and amphotericin-B. To study the interaction of amphotericin-B with polymorphonuclear leukocytes (PMN), purified human PMN were incubated with 200 mg of nylon wool fiber for 60 min either in the absence or presence of 2 mM EDTA. PMN were recovered in acid citrate dextrose solution and were suspended in balanced salt solution for determination of their aggregation properties. The cells exposed to nylon wool fibers without EDTA aggregated in response to concentration as low as 1.25 micrograms/ml of amphotericin-B. Cells initially treated with EDTA, however, failed to aggregate. Serum from a patient treated with amphotericin-B aggregated PMN exposed to nylon wool fiber but not control cells, whereas serum taken before amphotericin was given without effect on the PMN treated with nylon wool fiber. Amphotericin-B at 5 micrograms/ml failed to potentiate the release of beta-glucocuronidase or lactic dehydrogenase by PMN treated by nylon wool beyond that seen with exposure to the fibers alone. Rabbit peripheral blood was similarly incubated with nylon wool fibers and the recovered PMN were infused into recipient rabbits that had received 1 mg/kg of amphotericin-B intravenously 1 hr prior to the infusion of the leukocytes. Rabbits were sacrificed 30 min after transfusion of PMN, and their lungs were excised for histologic sectioning. Those rabbits receiving a combination of amphotericin-B and 4 x 10(7) nylon-wool-fiber-treated PMN had evidence of pulmonary hemorrhage and accumulation of leukocytes in the pulmonary vasculature whereas those animals who received such cells alone had normal appearing lung tissue. In summary, amphotericin-B at concentrations achievable in vivo enhanced the aggregation of PMN damaged by incubation with nylon fiber with subsequent accumulation of the phagocytes in pulmonary tissue.

Amphotericin B↗
PubMed2005

Discrimination of nylon polymers using attenuated total reflection mid-infrared spectra and multivariate statistical techniques.

Nylons are an important class of synthetic polymers, from an industrial, as well as forensic, perspective. A spectroscopic method, such as Fourier transform infrared (FT-IR) spectroscopy, is necessary to determine the nylon subclasses (e. g., nylon 6 or nylon 6,6). Library searching using absolute difference and absolute derivative difference algorithms gives inconsistent results for identifying nylon subclasses. The objective of this study was to evaluate the usefulness of peak ratio analysis and multivariate statistics for the identification of nylon subclasses using attenuated total reflection (ATR) spectral data. Many nylon subclasses could not be distinguished by the peak ratio of the N-H vibrational stretch to the sp(3) C-H(2) vibrational stretch intensities. Linear discriminant analysis, however, provided a graphical visualization of differences between nylon subclasses and was able to correctly classify a set of 270 spectra from eight different subclasses with 98.5% cross-validated accuracy.

Journal Article↗
PubMed2006

Adsorption of papain with Cibacron Blue F3GA carrying chitosan-coated nylon affinity membranes.

Covalent coupling of chitosan (CS) to activated nylon membrane was performed after the reaction of the microporous nylon membrane with formaldehyde. Non-specific adsorption on the CS-coated nylon membrane decreased greatly, compared with plain nylon membrane. The dye Cibacron Blue F3GA (CB F3GA) as a ligand was then covalently immobilized on the CS-coated membranes. Physical properties of the composite membrane and its applications in affinity membrane chromatography were examined. The contents of CS and CB F3GA-attached membranes were 89.6 mg/g nylon membrane and 146.1 micromol/g nylon membrane, respectively. These CB F3GA-attached composite membranes were used in the papain adsorption studies. Higher papain adsorption capacity, up to 235.3mg/g affinity membrane, was obtained. The adsorption isotherm fitted the Freundlich model well. Significant amount of the adsorbed papain (about 94.3%) was eluted by 1.0M NaSCN at pH 9.0. Experiments on regeneration and dynamic adsorption were also performed. It appears that CB F3GA-CS nylon membranes can be applied for papain separation without causing any denaturation.

Adsorption↗
PubMed2004

Skin closure in carpal tunnel surgery: a prospective comparative study between nylon, polyglactin 910 and stainless steel sutures.

OBJECTIVE: To compare the cosmetic outcome, pain and tenderness around the operation scar of carpal tunnel syndrome surgery using either nylon, polyglactin 910 or stainless steel sutures for skin closure. METHODS: A randomised clinical trial comparing nylon, polyglactin 910 or stainless steel sutures for skin closure in 61 patients undergoing carpal tunnel syndrome surgery was performed. Pain, tenderness, scar hypertrophy, redness and the presence of granulomas were assessed in all patients at ten days and six weeks after surgery and compared by non-parametric statistical tests. RESULTS: Adequate surgical decompression of the median nerve could be achieved in all patients. All but two patients experienced significant relief of tingling of the fingers. Nearly all patients reported some degree of discomfort around the scar. At ten days, the mean pain score was 1.7 (+/-2.2), 3.1 (+/-2.3) and 1.9 (+/-2.3) for the nylon, vicryl and steel groups, respectively. At six weeks, the pain score was 3.6 (+/-3.1), 3.4 (+/-2.6) and 2.7 (+/-2.1) for the nylon, vicryl and steel groups, respectively. The infection rate was 0%, 8% and 0% for the nylon, vicryl and steel groups, respectively. Suture granulomas were significantly more present in the vicryl group (p<0.05). There were no statistical differences in redness or hypertrophy of the wound between the three groups. CONCLUSIONS: Nylon and stainless steel sutures are both suitable for skin closure after carpal tunnel surgery. Based on this study, absorbable vicryl sutures should not be used, since the incidence of infections and the presence of suture granulomas was much higher than in the nylon and steel suture groups.

Adult↗
PubMed2006

[Establishment and evaluation of reproduction of middle cerebral artery occlusion to produce cerebral ischemia with autologous blood clot and nylon thread in rat].

OBJECTIVE: To reproduce cerebral ischemia using middle cerebral artery, occlusion (MCAO) method with autologous blood clot and nylon thread in rat. METHODS: Rats were randomly divided into sham operation group (n=10), suture occlusion group (n=12), thrombus suture occlusion model group (n=12) in which both autologous blood clot and nylon thread were used (thrombus occluded group). Cerebral ischemia as a result of MCAO in suture occlusion group was replicated by insertion of nylon thread. In thrombus occluded group, a polyethylene catheter containing a nylon thread was inserted into the middle carotid artery via external carotid artery, and the nylon thread was pulled out to an appropriate length to allow blood to coagulate. Fifteen minutes later, thrombin was injected, and the nylon thread was re-inserted to complete MCAO. Specimens were taken after ischemia for 6 hours. Neurological symptoms were observed, brain water ratio and the cerebral infarction size were measured, and the pathological changes in the brain tissue were observed. RESULTS: Compared with sham operation group, the evaluation score of neurological symptoms was significantly higher, and water content and cerebral infarction size were larger in suture occlusion group and thrombus occluded group (all P<0.01); the pathological changes of the brain were also more marked. Compared with suture occlusion group, thrombus occlusion group showed no differences in evaluation score, water content, cerebral infarction size and pathological changes of the brain (all >0.05). CONCLUSION: In rats, occlusion of middle cerebral artery with autologous blood clot and inserted nylon thread can result in the functional lesion, edema and the pathological changes in the brain. The MCAO reproduced by this method could produce thrombotic obstruction of the middle cerebral artery for the experimental study of cerebral ischemic/reperfusion injury, and it could prevent hemorrhage in the process of replication of animal model and in the course of thrombolysis therapy in the clinic. The model has the advantages of precision of the occlusion site, production of constant cerebral infarction size, easier performance and good repeatability.

Animals↗
PubMed1983

Experimental fixation of femoral osteotomies by cerclage with nylon straps.

Following the successful experience of Partridge in the fixation of human femoral fractures by nylon-strap cerclage, this research in 23 mature dogs was performed to compare nylon-strap with wire-loop cerclage for healing periods of up to 12 weeks. Supplemented by intramedullary fixation with Steinmann pins, long oblique femoral osteotomies were fixed in one femur of each dog by nylon straps and in the other femur by wire loops, at separate operations. The nylon straps were all secured at the same tension by a special "gun." The wire loops were all secured at the same tension by the Rhinelander tightener-twister. Half of the nylon straps had "bumps" along the inner surface, which were added by Partridge in an effort to circumvent the microvascular disturbance reported with Parham bands. On examination by microangiography and correlated histology, all of the osteotomies, regardless of the type of fixation, showed good progress toward osseous union. After fixation by wire cerclage no loss of position or disturbance of blood supply was noted. After fixation by nylon straps slight (clinically insignificant) longitudinal displacement, attributed to slight lengthening of the straps, with consequent loosening was noted in all cases. This loosening was considered advantageous because it appeared to be responsible for the unexpected lack of impairment of the vascularization of the underlying cortical bone by any of the straps. The bumps on the undersurface of some of the straps were, thus, of no vascular advantage, and their presence made accurate fixation of the ostectomy fragments more difficult on the small bones. These studies support the value of fixation by plain nylon straps and show their advantage over straps with bumps for fixation of long oblique single osteotomies of bones the size of the canine femur.

Animals↗
PubMed1994

Nylon-6 cylinders and a sponge-like derivative as supports for immobilizing trypsin.

1. Two types of nylon-6 supports (small cylinders and a sponge-like derivative) were prepared for immobilizing enzymes. Nylon-6 beads were solubilized by immersion in 80% formic acid and then reprecipitated using two different types of non-solvent solutions (distilled water or a 1:1 acetone:water solution) giving rise to a sponge-like derivative and to a colloidal suspension, respectively. The latter was molded into a thin thread which was cut into small cylinders. 2. Trypsin (EC 3.4.21.4) was covalently bound to glutaraldehyde-activated nylon-6 cylinders as well as to the sponge-like derivative. The maximum (100%) apparent initial enzymatic activity was found for the trypsin bound to small cylinders, while the initial activity of trypsin bound to the sponge-like material was 61% in comparison with that of trypsin-small cylinders, under the same conditions of enzyme immobilization reaction (1 g of nylon support and 5 ml of 1.3 mg/ml trypsin in 0.1 M sodium phosphate buffer, pH 8.5, at 10 degrees C for 18 h) and of enzymatic reaction (1 g of trypsin-nylon in a batch reactor, 2 ml of 0.7% w/v azocasein solution in 50 mM borate buffer, pH 8.5, at 37 degrees C, with shaking, for 1 h). However, the decrease of activity after enzyme immobilization was more conspicuous for the trypsin-small cylinders than for the trypsin-sponge. The former retained approximately 25% of its initial activity, while the latter retained approximately 67% of its initial activity, after seven cycles of utilization for 1 h, pH 8.5, at 37 degrees C and 8 days of storage, pH 8.5, at 4 degrees C in the presence of azocasein. 3. Scanning electron microscopy was performed to visualize the surface of the support after each step of the immobilization process. The electron micrographs show that the two types of nylon supports had a rough surface, which became rougher and full of craters after treatment with 5 N HCl. On the other hand, the partially hydrolyzed nylon surface acquired the appearance of Swiss cheese after treatment with 2.5% glutaraldehyde. After reaction with the enzyme molecules the surface became rougher again.

Caprolactam↗
PubMed1990

Reaction of the rabbit corneal endothelium to nylon sutures. A SEM study.

Nylon and stainless steel sutures separately placed deeply into rabbit corneas by splitting the stroma for a few millimeters, without closing sutures, remained in the cornea for two, four and six weeks respectively. In contrast to the stainless steel sutures an extensive tissue reaction could be observed clinically around the nylon sutures within a few days and was still present after 4-6 weeks. On the endothelial side, covering of the nylon with fibroblast cells took place very slowly, this in contrast with stainless steel. Irritation of the tissue and an oedematous appearance of the endothelium around the nylon suture was the result. At first a kind of collagen network, often mixed with inflammatory cells, was deposited on the nylon material before fibroblast cells could grow in. Covering of the stainless steel started quite soon after implantation, without preliminary deposition of collagen material. The reason for this phenomenon must be sought in the high free surface energy of the stainless steel, which attracts cells, in contrast to nylon which has a very low free surface energy.

Animals↗
PubMed1977

Changes in the structure of intra-ocular nylon.

When using a nylon thread for the attachment of a pseudophakos to the iris, it may happen that the suture is slung tightly around the implant-lens. In such a case this constitutes a clinical experiment where is one and the same eye one part of the nylon thread is in its normal state (the cut-off ends) and the rest is in a stretched state, both under the same environmental conditions and for the same length of time. The differences in structure of the parts of the nylon thread are thus fully comparable. Clinical observatons show that when the nylon thread is under tension it will be eroded by chemical influences. It does not make any difference whether the nylon is used for corneal, scleral or intra-ocular suturing. The duration of the observations is still too shor to predict the behaviour of nylon which is not stretched.

Cataract Extraction↗
PubMed1982

Histological and scanning electron microscopic study of tissue invasion of Bangerter nylon implant after enucleation.

An incidentally extirpated Bangerter-type nylon implant was examined by light microscopy and scanning electron microscopy. Three months after implantation, the implant was densely filled with tissues, which were shown by light microscopy to be muscle cells in the margin of the implant; the muscle cells were fixed there at the time of implantation, and fibrocytic cells were inside the implant. Scanning electron microscopy showed interlacing fibrous cells with erythrocytes and leukocytes among the nylon fibers, lamellar accumulation of fibrous cells around nylon fibers, and a smooth surface of the margin of the nylon implant. This invasion of fibrous cells into the nylon implant is one reason why the Bangerter type of nylon implant rarely falls out of the orbital socket.

Connective Tissue↗
PubMed1980

Immobilization of antibodies on nylon for use in enzyme-linked immunoassay.

Antibodies were immobilized by covalent linkage on nylon balls and powder for use in solid-phase enzyme-linked immunoassays. Covalent linkage of antibody to nylon was accomplished by treatment of partially hydrolyzed nylon with glutaraldehyde or carbodiimides. Up to 0.74 microgram of immunoglobulin G per mm2 nylon could be immobilized, whereas only 0.02 microgram per mm2 could be adsorbed to polystyrene, and the binding to nylon was stable. This eliminated the problem of antibody desorption noted in conventional enzyme-linked immunosorbent assay which are based on simple adsorption to plastics, and gave more reproducible results. The method was also more sensitive, detecting levels of approximately 1 ng per ml of immunoglobulin E in clinical samples. Further, antibodies coupled to nylon balls remained bound under conditions that dissociate antibody-antigen complexes, which permitted reuse of the immobilized antibodies for immunoassays.

Animals↗
PubMed1990

Haptenated nylon-coated polystyrene plates as a solid phase for ELISA.

An ELISA system, based on the novel use of a hapten-nylon conjugate as solid-phase coating antigen, has been applied in the screening of hybridoma cultures for anti-hapten monoclonal antibodies directed against the herbicide atrazine and its derivatives. Conjugation of a 2-aminocaproic acid derivative of atrazine with DCC to polyamide (Nylon 6) gave haptenated nylon which was soluble in aqueous cresol-ethanol mixtures and adsorbed efficiently on polystyrene microtitre plates. Reproducible ELISA results were obtained with culture supernatants of hybridomas derived from spleen cells of mice that had been immunized with atrazine-bovine serum albumin conjugates. Satisfactory results were also obtained with a water soluble peptide conjugated to nylon for use as a coating antigen in an ELISA. Plates coated with hapten-nylon as antigen have the added advantage that they can be stored at room temperature for at least 6 months without loss of activity. Nylon therefore appears to have general applicability as a carrier for both non-polar and polar haptens in the preparation and use of coating antigens.

Adsorption↗
PubMed1997

Effect of nylon suture diameter on induced astigmatism after phacoemulsification.

PURPOSE: To prospectively compare the clinical results of 10-0 and 9-0 monofilament nylon sutures after phacoemulsification with poly(methyl methacrylate) intraocular lens implantation through a 4.0 mm cruciate incision. SETTING: Department of Ophthalmology, Ramón y Cajal Hospital, Madrid, Spain. METHODS: One hundred eyes with cataract were randomly assigned to have surgery using a 10-0 or a 9-0 nylon suture. Except for suture diameter, identical surgical methods were used in every case. Data on uncorrected visual acuity, keratometry and postoperative astigmatism were analyzed up to 12 months after surgery. RESULTS: Both groups had similar uncorrected visual acuity. Mean postoperative corneal astigmatism was against the rule in the 10-0 nylon suture group and with the rule in the 9-0 nylon suture group. Significant differences were found between groups (P < .05). CONCLUSION: Both suture diameters offered satisfactory clinical results. Patients with preoperative with-the-rule astigmatism might benefit from 10-0 nylon sutures and those with preoperative against-the-rule astigmatism, from 9-0 nylon sutures.

Aged↗
PubMed1997

Determination of potential migrants present in Nylon 'microwave and roasting bags' and migration into olive oil.

Two groups of potential migrants were found in Nylon "microwave and roasting bags' (MRBs): volatile compounds were released at cooking temperatures and non-volatile compounds were extracted with methanol and/or water. A dynamic headspace system at 200 degrees C followed by gas chromatography (GC) coupled to mass spectrometry (MS) was used for determination of volatile compounds. Cyclopentanone (31.7 mg/bag), 2-cyclopentyl cyclopentanone (17.4 mg/bag), hexadecane (2.6 micrograms/bag), heptadecane (3.2 micrograms/bag), octadecane (3.0 micrograms/bag) and epsilon-caprolactam (5.0-35.5 mg/ bag) were the main volatile compounds present in the MRBs. High performance liquid chromatography (HPLC) and mass spectrometry were combined for identification and quantification of non-volatile compounds extracted with methanol (46.0 mg/bag). Nylon 6,6 cyclic monomer and cyclic oligomers up to the tetramer and Nylon 6 monomer and cyclic oligomers up to the octamer were identified and quantified, confirming that the plastic was made of Nylon 6,6 and Nylon 6 polymers. The same non-volatile compounds (except Nylon 6 heptamer and octamer) were found to migrate into olive oil at 175 degrees C for 1 h. A total of 0.916 mg/dm2 (19.2 mg/bag) of non-volatile compounds migrated into olive oil (41.8% of those quantified in the plastic material).

Chromatography, Gas↗
PubMed1987

Specific inhibition of hybrid resistance in F1 hybrid mice pretreated with parent strain spleen cells. I. Induction of a nylon-adherent, Thy-1+Lyt-1+2- suppressor cell.

Hybrid resistance, which is observed in certain strain combinations when parent-strain bone marrow cells are grafted into lethally irradiated F1 hybrids, can be specifically overcome by the i.v. injection, 1 wk before the graft, of spleen cells syngeneic with the bone marrow graft. This phenomenon is due to a suppressor mechanism, induced in the spleen of the F1 hybrid by the injection of parent-strain spleen cells and mediated by a nylon-adherent Thy-1+Lyt-1+2- cell population of hybrid origin, because hybrid resistance can be inhibited by the transfer into a normal B6D2F1 of nylon-adherent Thy-1+Lyt-1+2- spleen cells from B6D2F1 mice pretreated with B6 spleen cells 1 wk earlier (B6-pretreated B6D2F1); spleen cells from B6-pretreated B6D2F1 mice not depleted of their nylon-adherent subpopulation cannot restore hybrid resistance when they are injected into a B6D2F1 rendered nonresistant by split-dose irradiation; and spleen cells from normal B6D2F1 mice cannot restore hybrid resistance when they are injected into B6-pretreated B6D2F1 hybrids. The suppressor cells specifically inhibit resistance against bone marrow cells syngeneic with the spleen cells used for pretreatment, because transfer of nylon-adherent B6-pretreated B6D2F1 spleen cells into a normal B6D2F1 does not enhance syngeneic B6D2F1 or parent-strain D2 bone marrow growth, and when injected into normal B6D2F1 hybrids, nylon-adherent spleen cells from B6D2F1 mice pretreated with D2 spleen cells 1 wk earlier (D2-pretreated B6D2F1) are not able to transfer the inhibition of hybrid resistance against B6 bone marrow cells. Moreover, the activity of the suppressor cells depends on the genetic environment of the hybrid host mice, because nylon-adherent B6-pretreated B6D2F1 spleen cells injected into normal B6C3F1 hybrids do not transfer an inhibition of hybrid resistance, and when injected into B6C3F1 hosts previously rendered nonresistant by split-dose irradiation, spleen cells from B6-pretreated B6D2F1 mice can, in contrast, transfer hybrid resistance.

Animals↗