Long-term reduction in poly(dimethylsiloxane) surface hydrophobicity via cold-plasma treatments.

Poly(dimethylsiloxane), PDMS, a versatile elastomer, is the polymer of choice for microfluidic systems. It is inexpensive, relatively easy to pattern, and permeable to oxygen. Unmodified PDMS is highly hydrophobic. It is typically exposed to an oxygen plasma to reduce this hydrophobicity. Unfortunately, the PDMS surface soon returns to its original hydrophobic state. We present two alternative plasma treatments that yield long-term modification of the wetting properties of a PDMS surface. An oxygen plasma pretreatment followed by exposure to a SiCl4 plasma and an oxygen-CCl4 mixture plasma both cause a permanent reduction in the hydrophobicity of the PDMS surface. We investigate the properties of the plasma-treated surfaces with X-ray photoelectron spectroscopy (XPS) and contact angle measurements. We propose that the plasma treated PDMS surface is a dynamic mosaic of high- and low-contact-angle functionalities. The SiCl4 and CCl4 plasmas attach polar groups that block coverage of the surface by low-molecular-weight groups that exist in PDMS. We describe an application that benefits from these new plasma treatments, the use of a PDMS stencil to form dense arrays of DNA on a surface.

Cold-plasma modification of oxide surfaces for covalent biomolecule attachment.

While many processes have been developed to modify the surface of glass and other oxides for biomolecule attachment, they rely primarily upon wet chemistry and are costly and time-consuming. We describe a process that uses a cold plasma and a subsequent in vacuo vapor-phase reaction to terminate a variety of oxide surfaces with epoxide chemical groups. These epoxide groups can react with amine-containing biomolecules, such as proteins and modified oligonucleotides, to form strong covalent linkages between the biomolecules and the treated surface. The use of a plasma activation step followed by an in vacuo vapor-phase reaction allows for the precise control of surface functional groups, rather than the mixture of functionalities normally produced. By maintaining the samples under vacuum throughout the process, adsorption of contaminants is effectively eliminated. This process modifies a range of different oxide surfaces, is fast, consumes a minimal amount of reagents, and produces attachment densities for bound biomolecules that are comparable to or better than commercially available substrates.

Relationship of family communication patterns to eating disorder inventory scores in adolescent girls.

This study attempted to identify risk factors for the development of the psychological and behavior traits associated with eating disorders. Subjects were 454 healthy, high school girls; their responses to the Eating Disorder Inventory (EDI) were correlated with information obtained through a personal-background questionnaire. Students who perceived their guardians as persons who always lectured them about their problems or discounted the importance of their problems scored significantly higher on the eight EDI subscales than did respondents who reported other perceptions. Students who perceived their guardians as unwilling to listen to their problems tended to score higher on all the EDI subscales; significant differences were found between the scores of those responding "always" and "never"/"rarely" willing to listen. Students who responded that they were always uncomfortable discussing problems with their guardians tended to have a higher mean score on all but the Drive for Thinness and Body Dissatisfaction subscales. The empirical data on the family interaction patterns support the theory that certain family relationships contribute to the development of the psychological and behavior traits assessed by the EDI.

Trampoline-related injuries.

Two hundred and seventeen patients who had sustained an injury during the recreational use of a trampoline were managed in the emergency room of Logan Regional Hospital in Logan, Utah, from January 1991 through December 1992. We retrospectively reviewed the charts and radiographs of these patients to categorize the injuries. Additional details regarding the injuries of seventy-two patients (33 per cent) were obtained by means of a telephone interview with use of a questionnaire. The injuries occurred from February through November, with the peak incidence in July. The patients were eighteen months to forty-five years old (average, ten years old); ninety-four patients (43 per cent) were five to nine years old. Eighty-four patients (39 per cent) sustained a fracture; fifty-four (25 per cent), a sprain or strain; forty-five (21 per cent), a laceration; and thirty-four (16 per cent), a contusion. Fifty-seven injuries (26 per cent) involved the elbow or forearm; forty-six (21 per cent), the head or neck; forty (18 per cent), the ankle or foot; thirty-three (15 per cent), the knee or leg; nineteen (9 per cent), the trunk or back; thirteen (6 per cent), the shoulder or arm; and nine (4 per cent), the wrist or hand. Thirteen patients (6 per cent) had a back injury, but none of them had a permanent neurological deficit. One patient who had an ocular injury was transferred to a tertiary care center. One hundred and fifty-six patients (72 per cent) were evaluated radiographically, fifteen (7 per cent) were admitted to the hospital, and thirteen (6 per cent) had an operation.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of bacillus-based biological control agents in integrated pest management systems: plant diseases.

ABSTRACT Bacillus-based biological control agents (BCAs) have great potential in integrated pest management (IPM) systems; however, relatively little work has been published on integration with other IPM management tools. Unfortunately, most research has focused on BCAs as alternatives to synthetic chemical fungicides or bactericides and not as part of an integrated management system. IPM has had many definitions and this review will use the national coalition for IPM definition: "A sustainable approach to managing pests by combining biological, cultural, physical and chemical tools in a way that minimizes economic, health and environmental risks." This review will examine the integrated use of Bacillus-based BCAs with disease management tools, including resistant cultivars, fungicides or bactericides, or other BCAs. This integration is important because the consistency and degree of disease control by Bacillus-based BCAs is rarely equal to the control afforded by the best fungicides or bactericides. In theory, integration of several tools brings stability to disease management programs. Integration of BCAs with other disease management tools often provides broader crop adaptation and both more efficacious and consistent levels of disease control. This review will also discuss the use of Bacillus-based BCAs in fungicide resistance management. Work with Bacillus thuringiensis and insect pest management is the exception to the relative paucity of reports but will not be the focus of this review.

The effect of nerve root lesioning on various somatosensory evoked potentials in the hog.

Somatosensory evoked potentials (SEPs) were recorded at the lumbar spine following stimulation of the tibial nerve (mixed-nerve SEP; MSEP), the sural nerve (specific nerve SEP; SSEP), and the skin corresponding to the L6 and S1 dermatomes (dermatomal field SEP; DSEP-L and DSEP-S) in the hog. To determine the sensitivity of these three SEPs to the single nerve root (S1 root) function, the effects of nerve roots lesioning were investigated. Cutting S1 nerve root reduced the peak-to-peak amplitude of MSEP by only 28% in comparison with baseline values. The relative amplitudes of SSEP, DSEP-L, and DSEP-S were decreased by 46%, 11% and 51%, respectively. When S1 nerve root was left intact and L5, L6, and S2 nerve roots were cut, the relative amplitudes of MSEP, SSEP, DSEP-L, and DSEP-S were decreased to 68%, 73%, 31%, and 74%, respectively. These results indicate that DSEP-S is as sensitive to the function of S1 nerve root as SSEP but the sensitivities of DSEP-S and SSEP are low in the hog. MSEP is shown unsuitable to monitor the single nerve root dysfunction.

Efficacy of intraoperative monitoring for pediatric patients with spinal cord pathology undergoing spinal deformity surgery.

STUDY DESIGN: A retrospective study of 38 pediatric patients with spinal cord pathology who underwent corrective spinal deformity surgery from January 1989 through June 1998. OBJECTIVES: To report reliability and specificity in obtaining intraoperative data in this population. These data were compared with monitoring results obtained in a group of pediatric patients with idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: Reports in the literature suggest intraoperative monitoring for patients with spinal cord pathology may be of limited value. No optimal monitoring protocol has been suggested for this population. METHODS: The study group consisted of 38 pediatric patients with a diagnosis of spinal cord pathology who underwent corrective spinal deformity surgery from January 1989 through June 1998. All patients had lower extremity function. Somatosensory and neurogenic motor evoked potentials were used to monitor neurologic status during surgery. These data were compared with data obtained in 429 pediatric patients with idiopathic scoliosis. Study patients were divided into Group I, those who had had spinal cord surgery (n = 20), and Group II, those who had not (n = 18). RESULTS: Somatosensory evoked potentials were obtained in 93.2% and remained consistent with baselines in 87.2% of the study group patients. Neurogenic motor evoked potentials were obtained in 50.8% of the study subjects and remained consistent in 76.6% of those cases. The false-positive rate was 27.1% in the study group, compared with 1.4% in the group with idiopathic scoliosis. The study group had no true-positive or false-negative findings. Group I data differed from Group II data. CONCLUSIONS: Intraoperative monitoring should be used in patients with spinal cord pathology who undergo surgery for spinal deformity. Monitoring should not miss a neurologic deficit but demonstrates greater variability, resulting in more frequent use of an intraoperative wake-up test.

Radiation exposure during fluoroarthroscopically assisted anterior cruciate reconstruction.

We prospectively evaluated the radiation exposure during 50 consecutive fluoroscopically assisted anterior cruciate ligament reconstructions. Three different methods of anterior cruciate ligament reconstruction were performed using either rolled fascia lata allograft or bone-tendon-bone autograft. For the 50 procedures, total time using the fluoroscope was 119.61 minutes, or 2.38 minutes per procedure. The 16 primary fascia lata allograft reconstructions averaged 1.38 minutes of fluoroscope use per procedure compared with 4.69 minutes for the two revision allograft fascia lata surgeries, 3.14 minutes per procedure for the 30 primary bone-tendon-bone reconstructions, and 4.18 minutes per procedure for the two surgeries performed with an allograft meniscal transplant. The difference in exposure time between the 16 primary allograft fascia lata surgeries and the 30 primary allograft or autograft bone-tendon-bone surgeries was statistically significant. The average radiation exposure to the surgeon was 0.67 mrem per minute of fluoroscope use. It would take 7463.08 minutes of fluoroscope time, or 11,139 primary fascia lata allograft reconstructions, to exceed the recommended occupational exposure limit of 5000 mrem per year. It appears that the orthopaedic surgeon receives minimal radiation when using the fluoroscope to assist in anterior cruciate ligament reconstruction, especially when doing a primary fascia lata allograft procedure.

Earlobe repair: a new technique.

An alternative technique to the Z-plasty for repair of the earlobe rim has been presented. The V-flap technique is easier to perform and serves the same purpose of preventing notching at the earlobe rim.

Reaching children of the uninsured and underinsured in two rural Wisconsin counties: findings from a pilot project.

Debates about the accessibility, costs, and coverages of health care for the population at large have recently accelerated. This paper addresses some of the demographic, health, and fiscal ramifications of creating a preventive health care bridge to children in uninsured and underinsured families in two rural Wisconsin counties. The study findings revealed that the initial health status of children making a preventive health visit under a minimal copayment plan was noticeably worse than the status of those who had the free Early and Periodic Screening, Diagnosis, and Treatment (EPSDT) program available to them on a more or less continual basis. Upon their first visit, the children who did not have access to a free EPSDT program had a greater number of medical and dental health problems and fewer preventive dental care visits than their EPSDT contemporaries. Beyond a greater number of problems, however, we found no noticeable differences between the two groups in the types of health problems present (i.e. the clinical distribution of the problems was similar across the two groups). This paper also contrasts referral completion rates and rates of diagnostic confirmation of identified problems between the two groups. Finally, we provide estimates of the cost of coverage for each unprotected child.

Work of flexion after tendon repair with various suture methods. A human cadaveric study.

After flexor tendon repair there is often increased resistance to tendon gliding at the repair site, which is greater for techniques using increased suture strands or suture material. This increased "friction" may be measured as the "work of flexion" in the laboratory setting. Tendon repairs performed in zone 2 in human cadaver hands using the two strand Kessler, the lateral Becker, the six strand Savage, internal and dorsal tendon splint, or the external mesh sleeve techniques, had "work of flexion" measurements made both before and after the laceration and repair. The average increase in work of flexion was 4.8% for Kessler; 6.5% for Becker; 10.9% for Savage; 19.3% for the internal tendon splint, 16.2% for the dorsal tendon splint and 44.3% for the external mesh sleeve. The work of flexion was found to increase in direct proportion to the amount of suture material at the repair site.

Canine cadaveric study of flexor tendon repair using tendon splint: tensile strength and the work of flexion.

A total of 128 flexor tendon repairs in zone II were performed with various suture techniques using a canine cadaver model to determine the tensile strength, gap strength, and resistance to tendon gliding as measured by the work of flexion. The ultimate tensile strength in kilogram force (kgf) following tendon laceration and repair was the greatest after repair by the Savage technique (4.84 kgf) and the dorsal tendon splint technique (4.89 kgf), while the standard Kessler technique showed a strength of only 1.48 kgf. The greatest gap strength values were also obtained for the Savage and dorsal tendon splint techniques. The work of flexion increase was the greatest at 85.5% after repair using a mesh sleeve technique. While, the Savage and dorsal tendon splint techniques showed an increase of 24.3% and 25.1% with no significant difference compared to the other technique studied. Considering the values of these biomechanical parameters, we believe that the best flexor tendon repair techniques in the canine model are the Savage and dorsal tendon splint.

Effect of cyclic tension on lacerated flexor tendons in vitro.

The effect of tension on tendon healing was evaluated in vitro using cyclic tension and no tension groups of chicken flexor digitorum profundus tendons and histologic and immunohistologic techniques. A Vitrodyne force-loading machine was used for application of cyclic tension on partially lacerated chicken flexor tendons in culture media. Laceration sites under cyclic tension after 14 days were covered by newly proliferated fibroblasts, aligned in the direction of tension. This new growth was much thicker than that seen in the no tension group at the same time interval. Procollagen synthetic activity began at 3 days of culture in both groups. At 21 days, newly formed fibroblasts in the cyclic tension group were stained positive more strongly at the surface layer than in the deeper layers. In the no tension group, the staining was primarily in the surface layer. Cyclic tension stimulated the intrinsic response of lacerated flexor tendons significantly more than no tension did by enhancing proliferation and migration of fibroblasts, as well as stimulating collagen synthesis.

Tendon repair using flexor tendon splints: an experimental study.

Mechanical strength of tendon repair using Dacron tendon splints across the laceration site were evaluated in human cadaver profundus tendons; the splints were placed both on the dorsal surface and internally within the tendon substance. Comparison was made to modified Kessler, Becker, and Savage repair techniques. Ultimate tensile strength was 2.55 kgf for the Kessler, 3.00 kgf for the Becker, 8.29 kgf for the Savage, 8.46 kgf for the internal tendon splint, and 8.10 kgf for the dorsal tendon splint; the Savage and both Tendon Splints techniques had significant higher tensile strength than the Kessler and Becker. Gap strength was 1.44 kgf for the Kessler, 2.22 kgf for the Becker, 2.45 kgf for the Savage, 2.05 kgf for internal tendon splint, and 3.15 kgf for the dorsal tendon splint. The dorsal tendon splint technique showed significant greater gap strength than the other four techniques. There was no significant difference in the magnitude of the gap during cyclic testing of these techniques; however, three of seven Kessler repairs failed and one of six Becker repairs failed. The results of these cadaver studies suggest that both tendon splint repair techniques are comparable to the Savage and may have sufficient strength to allow postoperative active motion against minimal resistance. Further in vivo testing is in order.

Work of flexion after flexor tendon repair according to the placement of sutures.

Tendon repairs comparing dorsal or volar placement of sutures were done on 36 flexor profundus tendons from 9 canine cadaveric paws. Three suture techniques were used. Work of flexion as a measure of resistance to tendon gliding was measured in the following groups: Groups 1 and 2: 4-strand Savage technique with 5-0 core suture, dorsal or volar placement; Groups 3 and 4: 4-strand Savage technique with 4-0 core suture, dorsal or volar placement; and Groups 5 and 6: tendon splint technique, dorsal or volar placement. The increase in work of flexion values were 11.3%, 14.1%, 12.2%, 37%, 20.5%, and 92.7% for Groups 1 through 6, respectively. The increase in work of flexion value in Group 4 was significantly greater than that in Group 3, and the value in Group 6 was significantly greater than Group 5. These data suggest that the work of flexion after tendon repair was influenced by the location of the suture material; volar location of suture material significantly increased the work of flexion value.

Cross-pin femoral fixation: a new technique for hamstring anterior cruciate ligament reconstruction of the knee.

A new method of femoral fixation for arthroscopic anterior cruciate ligament (ACL) reconstruction using semitendinosus and gracilis (ST/G) tendons is presented. Biomechanical evaluation of the method was performed with pullout tests using animal tissues simulating fixation of ST/G tendons passing around a 2.5-mm pin placed transversely through a femoral tunnel. Clinical assessment of 22 patients was performed according to IKDC, Tegner, Lysholm, isokinetic strength, and KT1000 standards. Fixation strengths ranged from 725 N to 1,600 N for yield and maximal loads to failure for 35-mm to 70-mm cross-pins. Clinical results at mean follow-up of 30 months showed one traumatic failure, IKDC 86% normal or nearly normal, Tegner 6 ave, Lysholm 93 ave, KT1000 86% < 3 mm side-to-side difference on maximal manual evaluation, and isokinetic strength testing of quadriceps 8% deficit with hamstrings 8% deficit. Cross-pin fixation of ST/G tendons may be one of the strongest modes of femoral graft attachment yet devised. Our clinical outcomes in this initial series compare well with previous reports of ACL reconstruction regardless of graft or technique.

Effect of motion and tension on injured flexor tendons in chickens.

This study was undertaken to evaluate the individual effects of motion and tension on the healing response of injured flexor profundus tendons in chickens. Partial midsection transverse lacerations of the profundus tendons were produced in 53 chickens. Postoperatively, they were assigned randomly to four management groups: both motion and tension; only motion, no tension; no motion, only tension; no motion and no tension. Biomechanical results at 4 weeks showed that breaking strength significantly increased with both motion and tension, significantly decreased with neither, and was intermediate with only motion or only tension. Histologic evaluation generally showed the greatest cellular activity with both motion and tension, the least with neither, and an intermediate response with one or the other alone. Collagen fiber staining was increased primarily in the tension groups. The finding that both motion and tension enhance the tendon's response to injury encourages the development of active mobilization protocols following tendon repair.

Flexible intramedullary nailing of subtrochanteric fractures of the femur. A multicenter analysis.

In a retrospective, multicenter analysis, 79 subtrochanteric fractures of the femur were treated with flexible intramedullary nails. Seventy fractures were traumatic in origin, three were pathologic, and six occurred in spinal cord patients. All of the fractures healed, and there were no fixation failures. Thirteen patients (16%) required adjunctive internal fixation, bone grafts, or postoperative traction. Shortening greater than 1 cm occurred in four patients (5%). Reoperation with one week of surgery was necessary in eight patients (10%). The single greatest complication was knee complaints, which occurred in 17 patients (21.5%). However, only six of these patients required revision prior to fracture union. In one patient a deep wound infection developed, which eventually healed without evidence of osteomyelitis. All patients who were ambulatory before their fracture were able to bear weight.

Three-port perineal sparing technique.

The records were reviewed of 103 patients with low-lying pelvic malignancies irradiated with a skin-sparing technique involving use of a pair of anteroposterior-posteroanterior opposed ports and a direct perineal port. Patients had rectal, anal, cervical, vaginal, urethral, or vulvar cancer. Use of a special lead compensator allowed the three beams to be applied perpendicularly to the surface, while delivery of a homogeneous dose to the pelvis and perineum was maintained. Skin dose with this method was greatly reduced compared with that delivered with simple opposing or four-port techniques, in which irradiation is tangential to the surface at the perineum. Acute perineal skin irritation was assigned a grade between 0 and 3, with grade 0 representing the least amount of irritation. All patients were in the grade 0 or grade 1 category. Patients treated for low-lying rectal carcinoma showed no increase in perineal recurrences when compared with historic control subjects. Use of this approach allowed delivery of adequate doses to the pelvis and perineum and a definite decrease in local toxic effects, and local control was not compromised.