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Biomedical subjects

J R Wendt

Publications and source records attributed to J R Wendt.

At least 19 recordsLinked to original sources
PubMed2000

Three-dimensional control of light in a two-dimensional photonic crystal slab.

Optoelectronic devices are increasingly important in communication and information technology. To achieve the necessary manipulation of light (which carries information in optoelectronic devices), considerable efforts are directed at the development of photonic crystals--periodic dielectric materials that have so-called photonic bandgaps, which prohibit the propagation of photons having energies within the bandgap region. Straightforward application of the bandgap concept is generally thought to require three-dimensional (3D) photonic crystals; their two-dimensional (2D) counterparts confine light in the crystal plane, but not in the perpendicular z direction, which inevitably leads to diffraction losses. Nonetheless, 2D photonic crystals still attract interest because they are potentially more amenable to fabrication by existing techniques and diffraction losses need not seriously impair utility. Here we report the fabrication of a waveguide-coupled photonic crystal slab (essentially a free-standing 2D photonic crystal) with a strong 2D bandgap at wavelengths of about 1.5 microm, yet which is capable of fully controlling light in all three dimensions. These features confirm theoretical calculations on the possibility of achieving 3D light control using 2D bandgaps, with index guiding providing control in the third dimension, and raise the prospect of being able to realize unusual photonic-crystal devices, such as thresholdless lasers.

Journal Article↗
PubMed2000

Distal, dorsal superior extremity plasty.

Multiple deep wrinkles and redundant skin over the dorsal hand, wrist, and forearm develop and become of cosmetic importance to some patients as they age. Distal, dorsal superior extremity plasty was performed in selected patients by excising redundant skin and wrinkles from the dorsal hands, wrists, and forearms. The area of skin to be excised is elliptical, with the long axis of the ellipse centered over the wrinkles on the dorsal wrist. The amount of skin to be excised (i.e., the short axis of the ellipse) is determined by grasping the dorsal wrist skin, hence advancing the dorsal forearm and hand skin, while the patient flexes the wrist. This maneuver is performed to avoid excessive excision of dorsal wrist skin, which would cause decreased wrist flexion. The surgical procedure is performed with use of magnification to avoid sensory nerve injury. A relatively large volume of lidocaine is injected subcutaneously to increase the distance between the skin and nerves and therefore decrease the risk of nerve injury. The skin edges are undermined for 1 to 1(1/2) cm, and the wound is closed in two layers. The wrist is splinted in 30 to 45 degrees of extension to decrease wound tension. The procedure produces long-lasting, good to excellent cosmetic improvement and patient satisfaction. The dorsal wrist, hand, and forearm appear smoother and more youthful, and scars are relatively inconspicuous. Potential significant complications include injury to the superficial branch of the radial nerve and dorsal branch of the ulnar nerve, wound dehiscence, and decreased range of motion of the wrist. Use of magnification, a bloodless field, injection of a relatively large volume of local anesthetic (10 to 12 cc), knowledge of regional anatomy, and careful surgical technique decrease the risk of nerve injury. Avoidance of injury to the superficial sensory branches of the radial and ulnar nerves is absolutely necessary for patient satisfaction. Avoidance of injury to the wound edges with good surgical technique, postoperative immobilization with the wrist in an extended position, and subsequent advancement of the wrist to a neutral position for several weeks decrease the risk of wound dehiscence. Avoidance of excessive skin excision and prolonged wrist immobilization lowers the risk of decreasing range of motion. There have been no complications in patients who underwent this procedure.

Aged↗
PubMed1998

Treatment of complex postoperative lumbosacral wounds in nonparalyzed patients.

Postoperative infections after back operations can produce complex wounds with myonecrosis, deep dead space, and exposed orthopedic hardware, bone, and dura. Three ambulatory patients with complex postoperative back wounds that resulted from infections were treated successfully with antibiotics, debridement, irrigation, and closure of deep dead space with a superior gluteal muscle flap. Several surgical maneuvers can be performed to increase the length of the superior gluteal muscle flap. The inferior portion of the gluteus maximus was left intact to preserve gluteus maximus function. All three patients obtained healed wounds. The exposed A.O. plating system was not removed. There has not been any recurrence of infections. The superior gluteal muscle flap is a reasonable flap to fill deep dead space in the low back and has some advantages over free flaps.

Aged↗
PubMed1995

Vascular complications of a foreign body in the hand of an asymptomatic patient.

Foreign bodies in the hand are common clinical problems. A patient with a foreign body (glass) in the hand who was initially asymptomatic subsequently experienced ulnar artery erosion, thromboemboli, digital ischemia, and skin necrosis. These complications could have been prevented by removing the glass antecedent to the ulnar artery erosion. Excellent results were obtained by removal of the glass, excision of the diseased ulnar artery segment, and primary ulnar artery anastomosis.

Adult↗
PubMed1994

Indefinite survival of human skin allografts in patients with long-term immunosuppression.

The transplantation of a sufficient quantity of good quality skin is of great clinical importance. Severe burn patients lack adequate skin donor sites to cover their wounds with autografts. Patients with severe injuries and burns of areas such as the entire face are presently reconstructed with multiple full- or split-thickness skin grafts. The final result is a patchwork appearance of skin with inferior qualities to normal full-thickness facial skin. Before structures such as hands should be transplanted, each individual tissue component should be evaluated to determine whether the tissue will survive and function with immunosuppression. Skin is obviously an important part of the hand. One hypothesis tested is the ability of transplanted human skin to survive indefinitely with long-term immunosuppression. The early detection of rejection of transplanted organs is paramount in reversing the rejection phenomena and hence saving the transplanted organ. Another hypothesis tested is the ability of a synchronously placed, same-donor, same-recipient skin graft to be used to detect rejection of a transplanted organ. As the skin and kidney from the same donor have similar antigens and the transplantation of both these tissues is to the same recipient and immunological system, it is hypothesized that there will be a correlation of rejection between the transplanted skin and the transplanted organ. To test the above hypotheses a small skin graft was placed on renal transplant patients synchronously with renal transplantation. The skin allografts were followed by direct observation and biopsy at regular intervals and at the time of suspected rejection. The patients were treated with the usual renal transplant immunosuppressant drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1991

Cosmetic treatment of shagreen patches in selected patients with tuberous sclerosis.

Patients with mild forms of tuberous sclerosis may request cosmetic treatment of skin hamartomas. Treatment may consist of planning of an elevated shagreen patch with a Reese dermatome and/or laser treatment of facial angiofibromas. These precise patients, i.e., patients with a forme fruste of tuberous sclerosis, are more likely to have pulmonary involvement than patients with the usual complete disease form. A chest x-ray should be obtained in these patients to rule out pulmonary involvement. Half the patients with pulmonary involvement of tuberous sclerosis die an avoidable death from spontaneous pneumothoraces. Positive-pressure ventilation during anesthesia in these patients should be avoided or monitored closely.

Adult↗
PubMed1991

Transplantation of an osteoarthrotendinous allograft with autogenous soft-tissue coverage for thumb reconstruction.

A fresh-frozen thumb osteoarthrotendinous allograft and autogenous coverage were used to reconstruct a thumb. Immunosuppressants were not used. The components of the composite allograft are present and functioning 1 year post-operatively. Host cells have replaced and are replacing bone and tendinous structures. The "survival" of this osteoarthrotendinous allograft may have important implications in the treatment of patients with previous digital amputations, congenital absence of digits, and amputated digits that have failed replantation or are not replantable because of severely damaged vessels.

Amputation, Traumatic↗