Safety evaluation of recycling process used to produce recycled pulp for adult paper diapers.

Eight contaminants were used to perform a surrogate contamination test to evaluate safety of the process for producing recycled pulp for adult paper diapers. We performed a safety evaluation of the recycling process for producing recycled pulp following the European Food Safety Authority safety assessment for polyethylene terephthalate (PET) bottles using recycled PET. We also compared the first tier safety limit established on the basis of TTC (Climit) in the pulp that contained recycled pulp with residual contaminant concentrations (Cres). If Climit > Cres, there is no concern regarding safety of the recycling process. Climit was determined to be 0.46 mg/kg-pulp based on the human exposure threshold of 0.15 µg/person/day using the scenario in which a bedridden senior citizen uses four adult paper diapers manufactured with pulp containing 10% recycled pulp per day. Cres was derived from the initial concentration in used pulp (0.17 mg/kg-pulp), and decontamination rate was obtained from the surrogate contamination test. The Cres of the eight contaminants were between 0.0017 and 0.10 mg/kg-pulp, which were all below the Climit of 0.46 mg/kg-pulp. These results indicated there was no safety problem regarding this process for producing recycled pulp for adult paper diapers.

The arthroscopic square knot: a biomechanical comparison with open and arthroscopic knots.

PURPOSE: To compare the loop and knot security of arthroscopic square knots with other arthroscopic and open knots with the use of 2 commonly used suture types. METHODS: Five knot configurations were tested 12 times each. The arthroscopic square knot was compared with the open square knot, arthroscopic and open half hitches with alternating posts, and the Duncan loop. Load-to-failure testing was performed at a rate of 1.25 mm/sec, and cyclic testing was performed between 7 N and 30 N at a rate of 1 N/sec for 50 cycles. Two suture types were tested: No. 2 Ethibond suture and No. 2 FiberWire. RESULTS: Among the No. 2 Ethibond sutures, the arthroscopic Duncan loop had the highest load-to-failure at 165 N. The remaining knot types failed at between 142 N and 148 N. The load at 3 mm of lengthening was between 100 N and 120 N for all knots. The No. 2 FiberWire failed at higher loads than the No. 2 Ethibond suture for all knot types except the Duncan loop. The arthroscopic half hitches, arthroscopic square knots, and open half hitches all failed at between 220 N and 264 N. The open square knot failed at 188 N, and the Duncan loop failed at 147 N. The load at 3 mm of lengthening was between 130 N and 165 N for all knots except the Duncan loop, which failed at 95 N. With cyclic testing, arthroscopic square knots performed better than all knot types, but the differences were clinically insignificant. CONCLUSIONS: Arthroscopic square knots have the same or greater strength when compared with other arthroscopic or open knots tied with the same suture type, and they perform as well or better in the face of cyclic loads. Good knot security can be attained with all of the knots tested, regardless of suture type. Equivalent knots tied with No. 2 FiberWire fail at higher loads, except for those tied with the Duncan loop. CLINICAL RELEVANCE: Arthroscopic square knots can be used in the clinical setting with no compromise in function when compared with open square knots.

Polymers in contact with the body.

The clinical use of polymeric materials in the body to repair and restore damaged or diseased tissues and organs is substantially increasing on an annual basis. Concomitant with this use is an increase in materials related research on medically used polymers. Information on the historical and current clinical use of polymeric materials is provided in order to establish a basis for the philosophy and problems encountered in assessing the acceptability of various polymers in the biological system. The requisite properties which must be demonstrated by a polymer in contact with the body are discussed from two viewpoints, i.e., the effects of the material on the stability of the host and the effects of the host on the stability of the material. In addition, the effects of synthesis, processing, storage, sterilization, implantation, and possible degradation of polymers are discussed, poly(ethylene terephthalate) being used as an example.

Failure of knitted dacron as an arterial prosthesis.

The incidence of failure of knitted Dacron arterial prostheses is thought to be significantly greater than that reported in the literature. Five cases of immediate and late defects in grafts of various manufacture are reported and a sixth case is discussed. The development of increased porosity to achieve more complete graft healing is thought to play a role in both early and late graft failure. Although the precise etiologic mechanisms are yet to be determined, the Dacron fibers were noted to become separated with subsequent widening of the graft interstices with resulting hemorrhage through the "intact" prosthetic material. Related theories of explanation are reviewed, and guidelines for study of these defective prostheses are suggested. It is essential that this complication of arterial grafting be recognized and that pertinent clinical experiences be documented in the surgical literature.

Dacron femoral-popliteal bypass grafts in good-risk claudicant patients.

PURPOSE: To evaluate prosthetic femoral-popliteal (FP) grafts as bypass conduits in favorable patients with refractory calf claudication. SETTING: University-affiliated urban teaching hospital. METHODS: Cohort study of patency of 6-mm Dacron FP grafts used to treat patients with medically refractory calf claudication meeting the following criteria: nonsmoker; above-knee popliteal artery as an appropriate target vessel; > or =2-vessel tibial outflow; and postoperative anticoagulation and antiplatelet therapy. End points included primary and secondary FP graft patency, need for and outcome of subsequent intervention, limb amputation, and survival. RESULTS: From January 1998 through March 2001, 92 patients underwent 100 Dacron bypass grafts for medically refractory claudication. All underwent serial postoperative graft surveillance using duplex ultrasound. Using the Society for Vascular Surgery/International Society of Cardiovascular Surgery criteria life-table, primary patency was 84%, assisted primary patency was 88%, and secondary patency was 90% at 5 years. Two patients (2%) died during a mean follow-up period of 49 months (range 30 to 68). No limbs required amputation. Among 9 limbs in which Dacron FP bypass failed, 8 underwent subsequent successful autogenous bypass to the popliteal artery. CONCLUSION: In highly selected subjects with favorable features known to increase the likelihood of prosthetic graft patency, prosthetic FP grafts function well. Such patients undergo a simpler, more straightforward procedure than when autogenous FP bypass is performed. Subsequent success of autogenous FP repeat bypass suggests that previous prosthetic FP bypass does not threaten lower-extremity arterial outflow.

Strength and knot security of braided polyester and caprolactone/glycolide suture.

BACKGROUND: Appropriate suture selection is necessary in providing mechanical stability to soft tissue reconstructions. Caprolactone/glycolide (Panacryltrade mark) became a popular suture, possessing excellent handling properties; however, clinical observations questioned the knot security of caprolactone/glycolide. Caprolactone/glycolide is still available on many commercial suture anchor systems. This study compared the security of the knots and ultimate tensile strength of braided caprolactone/glycolide suture to that of a commonly used suture material, braided polyester (Ethibondtrade mark). MATERIALS: Suture knots of No. 2 braided polyester suture and No. 2 braided caprolactone/glycolide suture were submersed in a physiologic saline solution and stressed using a continuous (non-cyclic) load, simulating a single maximal loading event in a clinical setting. Continuous loading was done to achieve clinical suture knot failure (3-mm knot slippage), then continued until catastrophic suture failure (suture breakage) occurred. Ten trials of each suture were tested. RESULTS: Force required to cause knot slippage of 3 mm was greater for braided polyester than for braided caprolactone/glycolide (p <. 0001, unpaired Students' t-test). Forces resulting in catastrophic failure were greater for braided polyester than braided caprolactone/glycolide (p = .0284, unpaired Students' t-test). CONCLUSIONS: These data have important implications in the selection of suture materials for repair of soft tissue injuries. In the clinical setting, a single maximal loading event may result in suture failure. These data indicate that braided polyester possesses superior in-vitro mechanical properties and suggest that braided polyester may provide greater security in-vivo than braided caprolactone/glycolide suture.

Comparing Mersilene* tape and stainless steel wire as sublaminar spinal fixation in the Chagma baboon (Papio ursinus).

The development of segmental instrumentation has been a major advancement in the treatment of spinal problems, but the use of sublaminar stainless steel wire (SSW) has not been without untoward effects. This study reports a comparison of Mersilene* tape (MT) and stainless steel wire (SSW) used for sublaminar fixation in the Chagma baboon (Papio Ursinus). A similar comparative study has not been reported, although the local effects of sublaminar SSW in the spinal canal have previously been described. The adult Chagma baboon was selected as the experimental animal due to its partial upright posture and spinal anatomy, similar to that of the human. Six levels of the thoracolumbar spine were instrumented with custom designed Harrington hooks and regular one-quarter inch threaded rods used as a distraction system. The four intervening laminae were fixed to the rods using doubled-over, eighteen gauge sublaminar SSW in six cases and five millimeter MT in six cases. Computed axial tomography used to measure the AP diameter of the bony spinal canal revealed the AP space occupied by the SSW and MT to be 32 percent and 14.8 percent respectively. In the MT group, the overlying dura mater was found to be totally intact and revealed no signs of abnormal tissue response. A well-formed connective tissue membrane consisting of dense connective tissue surrounded the MT and was found to consist of more mature fibers than that found in the SSW group. The dura-implant interface was examined histologically and a distinct membrane was identified between the dura and the superficial aspect of the MT's, as well as intervening between the two MT's. Following removal of the MT, in contrast to the SSW, it was apparent that the underlying dura was not injured, most probably due to the soft consistency of the Mersilene* tape and the well-formed overlying membrane. On clinical grounds the fixation in both groups was adequate but the MT group formed a well-circumscribed membrane that made removal of the MT easier and potentially safer. The AP space occupied by the spinal implant was also found to be less with MT as opposed to SSW.

[Polyethylene terephthalate (PET)--health aspects and food packaging application]. / Politereftalan etylenu (PET)--aspekty zdrowotne i zastosowanie do pakowania zywnosci.

Polyethylene terephthalate (PET) due to its physicochemical properties, especially regidity and glass-like transparency is widely used as food packaging material. The relevant legislation states that substances may not migrate from food contacting materials in quantities that may cause undesirable changes in organoleptic properties of food coming into contact with such material. The lists of substances authorized for food contact plastic materials and requirements for the final product were established. The requirements concern global migration limits (60 mg/kg or 10 mg/dm2) and specific migration limits (SML) set for substances which, when migrate into food in grater quantities may cause risk for human health. For the products manufactured from PET the specific migration limits were set for terephthalic acid (7.5 mg/kg), for isophthalic acid (5 mg/kg), for isophthalic acid dimethyl ester (0.05 mg/kg) and for ethylene and diethylene glycol (30 mg/kg). PET may undergo thermal degradation resulting in formation of acetaldehyde, which may influence organoleptic characteristics of packaged foods changing taste and smell.

On the use of primary reference grade polydimethylsiloxane.

There has been an increase in the use of primary reference material as a standard for identifying the cellular response to biomaterials. One such material is NHLBI-DTB polydimethylsiloxane (PDMS). The PDMS was developed for blood contacting studies and is composed of PDMS backed on one side with mylar. The results of implantation studies of two different publications are discussed in light of the different materials and different surface topographies of each of the materials. The appropriateness of in vivo studies using this reference material is questioned.