Detection of perchlorate using Ag/DMAH(+) SERS-active capture matrices.

In this communication, the fabrication of SERS-active capture matrices for the detection of perchlorate is described. The amine groups of amine-modified magnetic microparticles were used to immobilize silver colloidal particles. Once immobilized, the silver was reacted with dimethylaminoethanethiol hydrochloride (DMAH(+)Cl(-)) to form a self-assembled monolayer (SAM). The DMAH(+) SAM exhibits reasonably good selectivity for perchlorate. It was shown that calibration curves could be generated by ratioing the perchlorate peak with a DMAH(+) peak that did not change upon interaction with the perchlorate ion. Flow experiments, using Ag/DMAH(+) capture matrices held in place by a magnet, showed instantaneous response to changes in perchlorate concentration. The use of solid phase extraction (SPE) to eliminate chloride ion interference was explored.

Detection of hexavalent chromium using gold/4-(2-mercaptoethyl) pyridinium surface enhanced Raman scattering-active capture matrices.

In this communication, the fabrication of SERS-active capture matrices for the detection of hexavalent chromium is described. The amine groups of amine-modified magnetic microparticles were used to immobilize gold colloidal particles. Once immobilized, the gold was reacted with 4-(2-mercaptoethyl) pyridinium (MEP) hydrochloride to form a self-assembled monolayer (SAM). The MEP SAM exhibits great selectivity for hexavalent chromium. It was shown that calibration curves could be generated by ratioing MEP peaks that increased in intensity upon complexation with chromate with a peak that did not change. Flow experiments, using Au/MEP capture matrices held in place by a magnet, showed instantaneous response to changes in chromate concentration.

Wrist position affects loading of the dorsal scaphoid: possible effect on extrinsic scaphoid blood flow.

Cadaver studies using radial artery injection techniques were used to study the vascular supply along the dorsal ridge of the scaphoid. These revealed an intraarticular membrane between the wrist capsule and the dorsal ridge of the scaphoid through which arteriolar vessels (25-100 microm internal diameter) passed. Biomechanical tests revealed that the extensor carpi radialis brevis may apply significant pressure to the dorsal ridge of the scaphoid when the wrist is flexed. The highest pressures occurred with the wrist flexed at 60 degrees or 90 degrees and in slight (15 degrees ) ulnar deviation. The authors suggest that these vascular and biomechanical factors may contribute to the aetiology for idiopathic osteonecrosis of the scaphoid.

Distal radial metaphyseal forces in an extrinsic grip model: implications for postfracture rehabilitation.

The purpose of this study was to establish the relationship between force at the distal radius and power grip force of the hand, a common functional and rehabilitation maneuver. This information will provide limits of allowable grip forces during postfixation rehabilitation and guide design requirements for fixation systems. By designing a model of power grip using the extrinsic hand musculotendinous units, we were able to compare grip force with force at the distal radius. Our results show that to obtain 10 N of grip force, approximately 26.3 N of force is transmitted through the distal radius, 52.4 N is transmitted through the radius and ulna combined, and 30.0 N needs to be applied to the flexor tendons. Fifty-one percent of the total forearm force was transmitted through the distal radius in this model. If all forearm forces were transmitted through the radius, 52 N of force would be transmitted through the distal radius to obtain 10 N of grip force. The clinical application of this model suggests that since failure forces of tested distal radius fixation systems range from 55 to 825 N, rehabilitation grip force should not exceed 10 to 159 N, depending on the type of fixation.

Painful conditions around the elbow.

This article discusses the origin and histology of conditions causing pain around the elbow as well as possible treatments. Specific conditions examined include epicondylitis and medial, posterior, and anterior musculotendinous injuries.

Treatment of unstable distal radius fractures: methods and comparison of external distraction and ORIF versus external distraction-ORIF neutralization.

Twenty-six closed unstable distal radius fractures were treated using a combination of internal fixation, external distraction (intraoperative), and, in some cases, up to 4 weeks of postoperative external fixation (neutralization). Intraoperative stability check determined the need for external neutralization. This combined technique allowed a comprehensive approach to even the most unstable fracture by merging the advantages of internal and external fixation. Up to 4 weeks of external fixation (neutralization) was not associated with the complications of external fixation usually reported.

Posttraumatic stiffness in the hand.

Maximalization of motion after healing is a primary goal of treatment when the surgeon is presented with a hand injury. The contribution of muscle/tendon, capsule and ligament, and the joint surface to the problem of posttraumatic stiffness is reviewed. Treatment possibilities for posttraumatic stiffness are presented and the importance of remobilization to the outcome of the care delivered is emphasized.

Design and biomechanics of a plate for the distal radius.

A dorsal plate for the distal radius was designed to provide rigid fixation and thus allow early motion. It functions as a blade plate, lessening the role of metaphyseal screws, and providing internal neutralization rather than compression. The rigidity and strength of the plate were compared to the existing T-plate in an unstable, extra-articular fracture model in paired, fresh-cadaver, axially loaded radii. The dorsal plate construct was significantly stronger and more rigid than the T-plate construct. The failure mode was similar for both plate types; 8 of 10 constructs failed with plate bending and screw loosening, while the oldest specimen pair showed primary bone failure. Compared to the T-plate, the dorsal plate transmitted a greater single axial load from the articular surface to the shaft.

Malignant bony tumors of the upper extremity.

Management of malignant upper-extremity tumors is a complex process that should be carried out using all the resources at the disposal of the patient and the surgeon. This article focuses on diagnosis, evaluation, pathology, and treatment.

External fixation for open fractures of the upper extremity.

Recent advances in external fixation hardware, frame application, and pin-site care have resulted in the evolution of external fixation as a safe and versatile technique. It provides skeletal stability, access to the site of injury, and allows early mobilization. It avoids the disadvantages of additional soft-tissue stripping and the foreign body introduction associated with internal fixation of open fractures. The utility of external fixation principles in open hand and wrist fractures is well established. Indications for external fixation in open fractures of the forearm, elbow, and arm are more restricted. External fixation in these locations should probably be limited to situations of marked fracture comminution, bone loss, or extensive soft-tissue damage.

The use of staples in hand surgery.

Staples can be used in a variety of surgical procedures on the hand. They provide excellent retraction of skin flaps for which sutures would normally be placed, and their use often decreases the need for manual retraction.

Flexor tendon lacerations in zone V.

Twenty-three patients with zone V flexor tendon lacerations rehabilitated by the Kleinert protocol were studied at an average of 46 months after trauma. Hand function was subjectively normal in only eight. Of fourteen patients who were employed at the time of injury, eight returned to their original occupations. Eight others were working at other jobs, and we considered six more capable of employment. Only one had a poor functional result that precluded occupational use of the hand. Pinch/grip strengths recovered to 85%/79% of the uninvolved side. Independent flexor digitorum superficialis/flexor digitorum profundus action was present in only seven patients. Sixteen regained full digital flexion. Extension loss averaged 25% at the wrist and 10% in each digit. As assessed by static two-point discrimination, sensibility was poor after associated median and ulnar nerve transections; this did not preclude good objective functional results. Complications included two tendon ruptures, proximal interphalangeal hyperextension in the presence of an unrepaired flexor digitorum superficialis, and limited motion in two patients after poor compliance in therapy. Tenolysis was needed in 4 of the 23. We now use a modified Duran technique for noncompliant patients and in those who are unable to extend their PIP joints because of weak intrinsic muscles.

Limited open surgical approach for external fixation of distal radius fractures.

In an effort to reduce treatment-related complications, a surgical procedure has been developed for the insertion and application of an external fixation device in the management of unstable fractures of the distal radius. Clinical experience with this device has demonstrated its effectiveness in reducing complications associated with pin insertion. The surgical technique is presented together with a case example. Results of laboratory tests corroborate our clinical experience and demonstrate the effectiveness of this technique in minimizing complications. Clinical results in 66 cases document the efficacy and safety of this technique.

Microvascular free-tissue transfers to the hand and upper extremity.

Hundreds of authors world-wide are responsible for the development of the present state of microvascular free-tissue transplantation. The applied technique represents a true developmental landmark in the field of surgery, now applicable to the broad spectrum of surgical subspecialties. In hand surgery, the revolutionary use of free-tissue transplantation has saved innumerable limbs, and improved the quality of life for tens of thousands of patients. In spite of our comfort level using these techniques and incorporating them into our armamentarium of patient care, we stand only on the threshold of microsurgical clinical applicability. The field has expanded substantially during the last 15 years. First, as a substitute for more conventional solutions to wound coverage problems, substituting for often cumbersome attached random or axial pattern pedicle flaps; then, incorporating neurosurgical techniques to provide sensibility to viable but otherwise anesthetic flaps, and kinetic function to transplanted muscle; and subsequently, with the incorporation of muscle, bone, and total joints. An ever-increasing knowledge of the metabolic consequences of ischemia and hypoxia on different types of tissue has allowed us to be even more aggressive in assessing indications for composite tissue transplantation. In the future we should anticipate continued advances in optics and magnification in the surgical microscope, with particular emphasis on three-dimensional perspective and enhanced video capabilities. Technologic development of instruments and suture material should continue helping to raise the capability of what is presently the most limiting factor--the surgeon--to a higher level of potential for his or her patients. Even with improved links to video equipment, stereoscopic imaging, or even more sophisticated visual images, the lowest common denominator is the skill of the microsurgeon; more rigorous technical development will be necessary during the surgeon's training period. Besides a fundamental knowledge of vascular clotting mechanisms and the effects of anticoagulation, we have only an elementary understanding of chemically induced vasospasm, and a developing appreciation of the physiologic impact of microsurgical trauma on small blood vessels, even with the most sophisticated and delicate techniques. As the field enlarges, our ability to deal with irreversible vessel spasm, inexplicable arterial or venous clotting, or the enormity of other complications associated with microvascular free-tissue transplantation, will only grow. A richer understanding of tissue biology will not only improve our technical capabilities, but will promote consideration of a

Advances in fracture management in the hand and distal radius.

Indications for internal and external fixation within the hand skeleton and distal radius have been presented and discussed. When used appropriately, these techniques will provide reliable fracture fixation and superior clinical results. Obviously, these techniques are not appropriate for all fractures. There remains a group of fractures well treated by more conservative methods. Additionally, some fractures exist which cannot be well treated by any method currently available. Nonetheless, these new techniques have added significantly to the clinical success available following the onset and treatment of complex fractures occurring within the hand skeleton and distal radius.

Proximal interphalangeal joint following traumatic arthritis.

The motivated patient with symptomatic post-traumatic PIP joint stiffness and discomfort has the potential for significant functional improvement. The specific treatment will depend on many factors, including residual joint architecture, alignment, and condition of the soft tissues. The careful surgeon will review all physical and roentgenographic data with the patient and involve her/him in the treatment plan. The function achieved eventually will depend as much on the motivated patient in the hands of a skilled therapist as on the surgeon's meticulous technique.

Management of severe hand trauma with a mini external fixateur.

Maintenance of length, alignment, and mobility while affording ready access for wound care has traditionally been a problem in the management of severe hand trauma. However, miniaturization of existing components of external fixation has provided a significant step in the solution of this problem. Twenty-eight fractures in severely traumatized hands in 24 patients have been managed using a Hoffman mini external fixateur. The patients' mean age was 26.5 years. The dominant hand was involved 60% of the time, and 80% of the population was male. Most fractures (80%) were open injuries with marked comminution, often intra-articular, frequently the result of gunshot wounds (60%). Mini external fixation has afforded proper wound care and maintenance of desired alignment. Complications have been few, while improved results (alignment, range of motion, strength, fracture union), have been demonstrated. Our surgical technique, results, and some illustrative cases are presented.

Acute calcium deposit in the hand of an 11-year-old girl.

A case of acute calcific deposit in the hand of an 11-year-old girl is presented. This is the first report of this entity in a child. The orthopedic surgeon and pediatrician are alerted to its existence and occurrence in the pediatric population.

Combined Maquet and proximal tibial valgus osteotomy.

A combined Maquet and proximal tibial valgus osteotomy has been used to treat patients presenting with anterior and medial compartmental degenerative arthritis. Patients with clinically symptomatic lateral compartmental disease, gross instability, or a nonfunctional range of motion were excluded. Thirty-four knees in 31 patients whose average age was 59.6 years were studied. Follow-up periods range from six to 36 months (mean, 16 months). Results have been tabulated with respect to the patient's preoperative radiographs and clinical knee ratings. The surgical technique has been the same throughout the series and is notable for the absence of metallic fixation and for the division of the tibiofibular joint proximally without an associated fibular osteotomy. Neither nonunion nor peroneal nerve dysfunction was encountered postoperation. To date, 68% of the results have been graded as good to excellent, 20% as fair, and 12% have failed. No correlation was found between preoperative radiographic rating and postoperative result.

Metabolism of dihydrouracil in Rhodosporidium toruloides.

Previous studies, including those done with a similar species, have indicated that dihydrouracil is formed by the breakdown of uracil and is degraded into N-carbamyl-beta-alanine. (Fink et al., J. Biol. Chem. 201:349-355, 1953; S. R. Vilks and M. Y. Vitols, Mikrobiologiya 42:567-583, 1973; O. A. Milstein and M. L. Bekker, J. Bacteriol. 127:1-6, 1976). In the present work the conversion of dihydrouracil to uracil is studied in Rhodosporidium toruloides, and the growth characteristics of mutants that have lost the ability to use dihydrouracil as a source of nitrogen are examined. It is concluded that dihydrouracil must be converted to uracil before catabolism of the pyrimidine ring can take place.