Plastic Sleeve Research Articles

Augmentation of implant purchase with bone cements: An in vitro study of injectability and dough distribution

Vertebroplasty is widely used to treat (augment) osteoporotic fractures of the spine. This technique--with or without metallic implants--might have more widespread indications, if the mechanics of the injection and distribution of the cement dough through cannulated instruments and implants were better understood. This study was performed to investigate injectability of calcium phosphate and acrylic bone cements through implant prototypes, which featured different perforated sleeve designs. Using a custom-made capillary rheometer, the forces needed to inject 10 mL of the cement dough through standard cannulas were measured in the first series of experiments. In the second series, plastic sleeves were attached to the rheometer, simulating the implant. In both series, the dough was injected into ambient laboratory atmosphere, and in the second series, cement distribution was analyzed by means of an optical system. Injection of cement dough through the cannulas required forces between 50 and 400 N in the case of acrylic cements and between 40 and 500 N in case of the calcium phosphate cements. Using different sleeves did not have a significant influence on the distribution of the cement dough around the sleeve. The amount of cement dough injected was reduced when a perforated implant was attached to the cannula. More material was delivered through the proximal holes of the implant, leading to a V-shaped distribution of the cement dough. Among topics to be investigated in future studies is determination of the injectability of cement dough into trabecular bone or bone-like structures.

P22. Accuracy of percutaneous lumbar pedicle screws using plastic vs. metal dilation sleeves

BACKGROUND CONTEXT: Stimulated EMG is used to test pedicle screws for cortical breach. Testing percutaneously placed screws with a metallic dilator in place may allow dissipation of current and give a misleading measurement of screw impedance.

Evaluation of Dowel Bars Installed in Airfield Concrete Pavement Construction Joints by Using Plastic Sleeves

This paper presents the results of an evaluation of the effectiveness of an innovative process for installing dowel bars in construction joints without drilling. The procedure involves inserting plastic sleeves with the same outside dimensions as the drilled holes into plastic concrete to create the holes for installation of the dowel bar, rather than drilling. The plastic sleeves are later removed, and the dowel bars are inserted in the holes left behind. To avoid any deleterious effects, the technique must produce dowel bar alignments that are comparable with those of the bars installed under the conventional method and must not cause any other problems. A field test was conducted to evaluate the viability of the new technique. The evaluation is based on the key factors that determine the engineering feasibility of the new procedure, which include dowel bar alignment, consolidation of concrete around the plastic sleeves, and the impact of the insertion techniques on pavement surface profile. The test results showed that the plastic sleeves can produce dowel bar alignments that are comparable with or better than those produced by the conventional drilling method, without any deleterious effects.

Evaluation of Dowel Bars Installed in Airfield Concrete Pavement Construction Joints by Using Plastic Sleeves

This paper presents the results of an evaluation of the effectiveness of an innovative process for installing dowel bars in construction joints without drilling. The procedure involves inserting plastic sleeves with the same outside dimensions as the drilled holes into plastic concrete to create the holes for installation of the dowel bar, rather than drilling. The plastic sleeves are later removed, and the dowel bars are inserted in the holes left behind. To avoid any deleterious effects, the technique must produce dowel bar alignments that are comparable with those of the bars installed under the conventional method and must not cause any other problems. A field test was conducted to evaluate the viability of the new technique. The evaluation is based on the key factors that determine the engineering feasibility of the new procedure, which include dowel bar alignment, consolidation of concrete around the plastic sleeves, and the impact of the insertion techniques on pavement surface profile. The test results showed that the plastic sleeves can produce dowel bar alignments that are comparable with or better than those produced by the conventional drilling method, without any deleterious effects.

A system of multiple biopsy forceps

A new system of flexible endoscopic biopsy forceps is described. These forceps are simple, cheap to produce, and disposable. These forceps take larger and less traumatized biopsies than do existing single biopsy forceps. The principle involves that of a central wire with a barbed spike at one end, to which sliding sprung steel jaws are attached. An outer plastic sleeve surrounds the central wire, and conventional-type handles activate the jaws. The device is passed along the biopsy channel of a fiberoptic endoscope, and the tissue to undergo biopsy is visualized. Opening and closing of the forceps occurs when the outer sleeve slides on the inner wire allowing the sprung steel jaws to open and close. With the jaws open, the barb is pushed into the tissue to undergo biopsy. The fishhook-like barb pulls back the tissue into the jaws, which bite the tissue at an optimal angle and can thus obtain cleaner and bigger biopsies. For the second biopsy, the jaws are simply reopened, and as the barbed spike again pierces the tissue, the first specimen is pushed along the central wire. Up to 6 biopsies are to be stored in this way, in a predictable order, with a single passage of the biopsy forceps through the endoscope.

Cryo-banking of great ape spermatozoa using human protocols and variation among males

To develop a resource of great ape sperm cells and test the hypothesis that great ape males, like human males, differ in production of sperm cells and in rates of sperm cell survival after exposure to similar processing for cryopreservation. Prospective trial in a cohort of normal male chimpanzees. Seven male chimpanzees ranging in age from 9.9 to 24.2 years were trained to provide semen samples using an artificial vagina. Samples were removed from the plastic sleeve of the device and placed into conical centrifuge tubes. The liquid fraction of semen was removed within 30 minutes and mixed with an equal volume of human commercial transport medium containing egg yolk and buffer (Refrigeration Medium, Irvine Scientific). Samples were transported to the andrology lab for semen analysis and cryopreservation. Briefly, the diluted semen was assayed, then mixed with an equal volume of glycerol containing cryopreservation medium (Freezing Medium, Irvine Scientific) and loaded into half cc straws with labeled handles. Straws were placed into a controlled-rate, nitrogen vapor freezing machine for slow cooling to -7 degrees C, seeding, cooling to -80 degrees C at -10 degrees/min and plunging into liquid nitrogen. A straw from each sample was subsequently thawed, diluted with culture medium, concentrated by centrifugation, and diluted to the original volume of the straw for assay of motility via CASA system. During a 20-month interval 93 semen samples from seven males were obtained for analysis and potential cryopreservation. Individual males provided between 5 and 29 samples. Males differed significantly (pyr<0.000005) in the number of sperm cells provided in each sample from averages of 79, 88, 454, 1858, 1138, 678, and 1640 million and in the percentage of motile cells available for cryopreservation from averages of 48, 4, 32, 27, 13, 18, and 47 percent. Between 5 and 26 samples were cryopreserved for each male. The ratio of progressive motility after thaw and washing compared to pre-freeze levels differed (p=0.03) between males (0.43, 0.16, 0.33, 0.23, 0.41, 0.30, and 0.17) and was not related to number of sperm in the ejaculate or the initial motility. Currently, 531 straws with estimated yields after thaw of 3,686 million motile cells have been banked for research uses and seven males are trained to provide samples on demand. These procedures have been extended to another great ape species, the bonobo. Male chimpanzees of varying ages can be trained to provide semen samples for analysis, research, and cryopreservation. Once trained, animals can be induced with rewards to provide samples on a regular basis. A cryo-bank has been developed with sperm cells from seven males. Even with delays of 3 to 6 hours between collection and initiation of processing for cryopreservation, progressively motile sperm cells survive standardized cryopreservation and thawing protocols. However, sperm survival rates vary significantly among males.

An experimental investigation of the electron energy dependence of the EPR alanine dosimetry system

The dose-to-water response of the EPR alanine dosimetry system for various electron beams used in radiotherapy is studied. The EPR alanine dosimetry system is established for high-dose dosimetry, usually transfer dosimetry of 60Co γ-rays. However, for clinical applications, where radiation qualities other than 60Co γ-rays are used, the behavior of the alanine dosimeter response needs to be further investigated. In the present work, electron beams from a clinical linear accelerator of the type Varian Clinac 2100 were used. Alanine dosimeters were irradiated with doses between 16 and 54 Gy in a plastic sleeve at the depths of dose maximum in a water phantom with electron beams of nominal energies of 6, 9, 12, 16 and 20 MeV (corresponding beam quality indices R 50 : 2.4, 3.4, 4.8, 6.5 and 8.2 cm 2 / g ). For the electron beams, the dose-to-water was monitored using a plane-parallel ion chamber, while for the 60Co γ-rays, the dose was monitored using a cylindrical chamber that was calibrated with water calorimetry. The obtained alanine dose-to-water responses for electrons relative to 60Co γ-rays indicated a small deviation from unity. An average relative response of about 0.97 for the electron beam qualities is indicated from the data. Possible explanations for the small observed response reduction relative to 60Co γ-rays are discussed.

Writing Résumés

Writing Résumés

Production of recombinant proteins by hairy roots cultured in plastic sleeve bioreactors.

Plant-based expression of recombinant proteins offers significant advantages over transgenic animal-and cell-based systems. Unlike bacteria, plants perform the complex protein-processing steps required to produce eukaryotic proteins in active form. In order to facilitate protein production and purification we used hairy root cultures as a secretion-based in vitro plant system. We utilized the green fluorescent protein (GFP) as our model protein and expressed it for secretion in tobacco hairy root cultures. For large scale production of GFP, we adapted the Life-Reactor trade mark plastic sleeve bioreactor for growth of hairy roots in cultures containing up to 5 L of medium. Yields higher than 800 micro g of GFP per liter of culture were obtained after 21 d of incubation, representing almost 20% of the total secreted protein. The use of the plastic sleeve bioreactor system for expression of proteins in hairy roots allows for continuous or inducible production and recovery, while maintaining absolute containment, of the recombinant product.

A study on the interplay between energy and matter transformation: the effect of elevated temperatures on the leaf morphology of Vitis vinifera var. Merlot

This investigation explores the relationship between increased energy levels and leaf morphology. It tests the idea that the causal agent of development is the dissipation of energy into transformed matter. The energy under which leaves developed was modified by increasing temperatures in grape cordons through wrapping them in clear plastic sleeves in the early spring. At the higher temperatures, and energy levels, there was a small but statistically significant decrease in leaf size and a change in organization the leaves. The decrease in leaf size may be due to a reallocation of resources, either to greater shoot growth as a previous study demonstrated or to the appearance of more vectors of development in the leaves, i.e. the appearance of more developmental subsystems. The leaves that grew under the higher temperature regime were more complex, perhaps indicating that the grapes on those same vines may produce more complex juice, another expression of more developmental subsystems. The change in organization in these leaves that developed at higher temperature argues that the causal agent in plant development is energy dissipation and the concomitant transformation of matter, the latter expressed in the appearance of more growth vectors.

A new removable implant analog.

A new implant analog system that improves the efficiency of the implant restoration's fabrication process is described. This 2-piece analog contains an outer plastic sleeve that is retained within the stone cast. The inner portion, a metal analog, can be easily removed and replaced within the plastic sleeve. Because the metal analog is removable, the time-consuming process of screwing and unscrewing the prosthesis- or abutment-retaining screws during laboratory procedures can be minimized. The prosthesis can remain secured to the analog during waxing, metal finishing, and porcelain buildup, yet is easily removed from the cast for inspection.

Alkali mass balance during the accelerated concrete prism test for alkali–aggregate reactivity

The alkali mass balance was calculated in concrete specimens submitted to the storage conditions of the Canadian standard CSA A23.2-14A concrete prism test for expansion due to alkali–aggregate reaction (AAR). The alkali concentration of both the concrete pore solution expressed under high pressure and the water below specimens in storage pails (bottom water) was measured. Measurements were conducted over a 1-year period, which corresponds to the length of the above test. Two reactive aggregates were tested [Potsdam sandstone (PO) and Spratt limestone (SP)]. Each aggregate was incorporated in two concrete mixtures ( mass concrete and structural concrete), for a total of four batches. Significant alkali leaching occurred at 38 °C while performing tests in high moisture storage conditions even though prisms were covered with plastic sleeves. After 52 weeks, the alkali loss ranged from 12% to 25% of the original Na 2O e content of the concrete, depending on the mixture proportioning and the aggregate type. After estimation of the proportion of alkalis fixed in cement hydrates, it appears that about 23% to 39% of the original alkalis released by the cement are quickly sorbed on aggregate surfaces or have rapidly migrated inside aggregate particles, which may have been incorporated with time in the AAR product. After 52 weeks at 38 °C, the pore solution alkalinity expressed from mass concrete made with PO was 250 mmol/l, whereas the alkalinity was 270 mmol/l in mass concrete incorporating SP. Since prisms of both mixtures were still expanding at 1 year, these alkalinity values are above the thresholds required for sustaining AAR in these concrete mixtures.

Aspiración endotraqueal, cepillado y lavado broncoalveolar

The aim of endotracheal aspiration is to eliminate secretions in patients with an artificial airway. All children with mechanical ventilation must undergo this procedure periodically. The frequency of aspiration depends on the type and quantity of the respiratory secretions and on the patient's clinical status. Aspiration should be performed by two people to maintain a greater degree of asepsis and to optimize stability of the airway and ventilation. Closed aspiration systems are available that allow aspiration without the need to disconnect the patient through a single probe that is constantly protected by a plastic sleeve and isolated from external environment. The most important risks of endotracheal aspiration are hypoxemia, mucosal injury, bronchospasm, arrhythmias, perforation of the airway with development of pneumothorax, accidental extubation, and infections. Bronchial brushing with a protected catheter and brochoalveolar lavage are used to analyze pulmonary infections. These techniques can be performed blind or through fibrobronchoscopy. They can also be used for the diagnosis of noninfectious pulmonary diseases such as alveolar proteinosis, alveolar hemorrhage or histiocytosis. Their adverse effects are similar to those of endotracheal aspiration.

A Simple Method to Improve the Efficiency of Transrectal Ultrasound Guided Prostate Biopsy

It is estimated that 190,000 cases of prostate cancer will be diagnosed in 20021 and transrectal ultrasound biopsy is the current diagnostic gold standard.2 The cancer detection rate for transrectal ultrasound biopsy has been estimated at 25% to 35%,3– 6 implying that more than 500,000 biopsies are performed annually. Unless a patient specifically requests, it is usually performed under minimal, if any, anesthesia due to the short (7 to 10 minutes) duration of the procedure.7 However, many patients complain that the ultrasound probe is painful, and all of them want the procedure to be over as quickly as possible. Although the procedure takes only a few minutes, the majority of the time is spent removing the specimen and reloading the biopsy gun. We present a simple method that reduces the time needed to obtain 10 biopsies to 120 seconds. METHOD At our institution the most time consuming portion of the biopsy is removal of the specimen from the biopsy needle. The usual removal method requires the physician performing the biopsy to hand the biopsy gun (Radioplast AB Biotpy, Bromma Sweden) to the assistant who opens it, removes the biopsy needle and places the specimen into a designated container of formalin. The specimen often adheres to the biopsy needle, requiring the assistant to immerse the needle in the formalin, and in many cases use another device (the plastic sleeve included in the packaging of the biopsy needle is commonly used) to scrape the specimen off the biopsy needle. When this is complete, the biopsy needle must be rinsed in saline to remove the formalin, reloaded and handed back to the physician. In our experience this process takes at least 30 seconds and frequently results in broken specimens which may be more difficult for the pathologist to mount, section and interpret. All the while the patient lays with the probe uncomfortably in the rectum. RESULTS In our method when the physician hands the biopsy gun to the assistant, he recocks it and points the tip into the mouth of the specimen container but not in contact with the formalin. He fires the biopsy gun and the specimen is expelled into the container intact, without contaminating the needle and with no further manipulation needed. Should the needle touch the formalin, it can be rinsed in saline without removing it from the biopsy gun. By using this simple method and pre-labeled specimen containers we have reduced the time needed for the biopsy portion of the transrectal ultrasound (10 biopsies) to 120 seconds. CONCLUSIONS While patients still experience some discomfort, they are often surprised and uniformly grateful that the procedure is over so quickly. This simple modification makes a common procedure dramatically faster, has no deleterious effect on the accuracy of the test, reduces the chance for needle stick exposure and may actually improve specimen quality. REFERENCES

A simple method to improve the efficiency of transrectal ultrasound guided prostate biopsy.

It is estimated that 190,000 cases of prostate cancer will be diagnosed in 20021 and transrectal ultrasound biopsy is the current diagnostic gold standard.2 The cancer detection rate for transrectal ultrasound biopsy has been estimated at 25% to 35%,3– 6 implying that more than 500,000 biopsies are performed annually. Unless a patient specifically requests, it is usually performed under minimal, if any, anesthesia due to the short (7 to 10 minutes) duration of the procedure.7 However, many patients complain that the ultrasound probe is painful, and all of them want the procedure to be over as quickly as possible. Although the procedure takes only a few minutes, the majority of the time is spent removing the specimen and reloading the biopsy gun. We present a simple method that reduces the time needed to obtain 10 biopsies to 120 seconds. METHOD At our institution the most time consuming portion of the biopsy is removal of the specimen from the biopsy needle. The usual removal method requires the physician performing the biopsy to hand the biopsy gun (Radioplast AB Biotpy, Bromma Sweden) to the assistant who opens it, removes the biopsy needle and places the specimen into a designated container of formalin. The specimen often adheres to the biopsy needle, requiring the assistant to immerse the needle in the formalin, and in many cases use another device (the plastic sleeve included in the packaging of the biopsy needle is commonly used) to scrape the specimen off the biopsy needle. When this is complete, the biopsy needle must be rinsed in saline to remove the formalin, reloaded and handed back to the physician. In our experience this process takes at least 30 seconds and frequently results in broken specimens which may be more difficult for the pathologist to mount, section and interpret. All the while the patient lays with the probe uncomfortably in the rectum. RESULTS In our method when the physician hands the biopsy gun to the assistant, he recocks it and points the tip into the mouth of the specimen container but not in contact with the formalin. He fires the biopsy gun and the specimen is expelled into the container intact, without contaminating the needle and with no further manipulation needed. Should the needle touch the formalin, it can be rinsed in saline without removing it from the biopsy gun. By using this simple method and pre-labeled specimen containers we have reduced the time needed for the biopsy portion of the transrectal ultrasound (10 biopsies) to 120 seconds. CONCLUSIONS While patients still experience some discomfort, they are often surprised and uniformly grateful that the procedure is over so quickly. This simple modification makes a common procedure dramatically faster, has no deleterious effect on the accuracy of the test, reduces the chance for needle stick exposure and may actually improve specimen quality. REFERENCES

Recognition of Occult Bladder Injury During the Tension-free Vaginal Tape Procedure

In Brief OBJECTIVE To identify signs and the etiology of occult bladder injury during the tension-free vaginal tape sling procedure. METHOD The charts of 140 women who underwent a tension-free vaginal tape procedure were reviewed, and complications were tabulated and analyzed. The tension-free vaginal tape procedure was performed in six fresh-frozen pelves to demonstrate the mechanism of the occult bladder injury. RESULTS Occult bladder injury was suspected when cystoscopy instillation fluid flowed from the plastic sheath that covers the prolene tape after the extraction of the tension-free vaginal tape trocar. Three of six cases of intraoperative bladder injury had occult bladder injury identified on repeat cystoscopic inspection. The bladder injury caused by the rough edge at the point of attachment of the tension-free vaginal tape to the trocar was reproducible in three of 12 tension-free vaginal tape applications in fresh-frozen pelves. Traction on the tension-free vaginal tape reapproximates the injured bladder edges and potentially promotes spontaneous healing. CONCLUSION Bladder injuries may go unrecognized during a tension-free vaginal tape procedure. Continuous seepage of water through the prolene plastic sleeve is suggestive of occult bladder injury and requires repeat cystoscopy to identify the potential site of injury. Water seepage through the tension-free vaginal tape plastic sleeve is indicative of occult bladder injury and requires repeat cystoscopic inspection of the bladder.

Recognition of occult bladder injury during the tension-free vaginal tape procedure

OBJECTIVE: To identify signs and the etiology of occult bladder injury during the tension-free vaginal tape sling procedure. METHOD: The charts of 140 women who underwent a tension-free vaginal tape procedure were reviewed, and complications were tabulated and analyzed. The tension-free vaginal tape procedure was performed in six fresh-frozen pelves to demonstrate the mechanism of the occult bladder injury. RESULTS: Occult bladder injury was suspected when cystoscopy instillation fluid flowed from the plastic sheath that covers the prolene tape after the extraction of the tension-free vaginal tape trocar. Three of six cases of intraoperative bladder injury had occult bladder injury identified on repeat cystoscopic inspection. The bladder injury caused by the rough edge at the point of attachment of the tension-free vaginal tape to the trocar was reproducible in three of 12 tension-free vaginal tape applications in fresh-frozen pelves. Traction on the tension-free vaginal tape reapproximates the injured bladder edges and potentially promotes spontaneous healing. CONCLUSION: Bladder injuries may go unrecognized during a tension-free vaginal tape procedure. Continuous seepage of water through the prolene plastic sleeve is suggestive of occult bladder injury and requires repeat cystoscopy to identify the potential site of injury.

Radiolucency adjacent to the tibial component in total knee arthroplasty.

This study determined the accuracy of standard radiographs in observing radiolucency adjacent to the tibial component in total knee arthroplasty. A model of the proximal tibia was used. Plastic sleeves of different heights were glued under the tibial tray to imitate radiolucency. By tilting the x-ray tube 1degrees at a time, an investigation was performed to determine how many degrees it would take to cover the heights of the different plastic sleeves. In a clinical study of patients at standard follow-up, 21 knees were examined using standard radiographs. Radiographs using image intensification were then taken of the same knees to obtain radiographs with views parallel to the plane of the tibial tray. The results of the study on the phantom showed that a 1degrees deviation of the x-ray beam from the optimal position would obscure a 0.5-mm "radiolucency." This was true for radiolucencies of 2, 3, 4, and 5 mm. This was confirmed in the clinical study where < or = 4 mm of radiolucency was obscured on standard radiographs. Therefore, standard radiographs cannot be used to determine radiolucency. The 2-mm radiolucency normally associated with loosening is not clinically valid.

Tunable chirped fiber Bragg gratings by a distributed heater

We propose a new design for introducing a tun- able chirp on a uniform fiber Bragg grating by a controllable temperature gradient. The device consists of an unchirped Bragg grating in a bare fiber that is mounted in a plastic sleeve whose surface is coiled with a length of wire heater. The desired temperature distribution produces a chirp on the grating and at a rate that can be adjusted by varying the current. We demonstrate an electrically tunable chirped fiber Bragg grating that enables a tuning range of an average chirp rate up to 0.93 nm/cm with an electrical power of 3.3 W. We also demonstrate a tunable chirped fiber Bragg grat- ing in which dispersion is adjustable from 21632 to 2667 ps/nm with an electrical power of less than 0.5 W. © 2001

Thermal analysis of dry sleeve bearings — a comparison between analytical, numerical (finite element) and experimental results

Thermal analysis of a plastic sleeve bearing in dry operation was investigated experimentally by Floquet et al. [Trans. ASME, J. Lubr. Technol. 99 (1977) 277]. For a comparison with the experimental results, Kennedy [Trans. ASME, J. Tribol. 103 (1981) 90] developed a numerical approach using the finite element method (FEM) that included the development of finite element equations for the case of a moving body heat conduction. In this investigation, both the experimental results of Floquet [Docteur-Ingenier thesis, Université Claude Bernard, Lyon, 1978] and the numerical results of Kennedy were compared with the results of the analytical method developed using the classical heat source method introduced by Jaeger [Proc. Roy. Soc. NSW 76 (1942) 203] and the heat partition principles of Blok [Proc. Inst. Mech. Engrs. 2 (1937) 222], which involves matching of the temperatures on either side of the contact interface. The non-uniform distribution of heat partition (as one body is stationary and the other moving) along the interface is addressed by matching the temperatures at the interface between the stationary and the moving bodies in relative sliding contact using the functional analysis approach originally introduced by Chao and Trigger [Trans. ASME 72 (1955) 1107]. The analytical results are found to be in excellent agreement with both the experimental and the numerical results.