Tissue-engineered skin in the healing of wound stumps from limb amputations secondary to purpura fulminans.

Currently wound treatment options of amputation stumps due to purpura fulminans include healing by secondary intention from wound debridement, split-thickness skin grafting, tissue and muscle flaps, plantar skin free transfer, skin expansion, artificial skin, and hyperbaric oxygen therapy. We saw a 6-month-old girl with purpura fulminans as a complication of meningococcemia. She developed necrosis of the distal extremities resulting in bilateral amputation of the lower limbs. Shortly thereafter the leg stumps also became necrosed and she underwent unsuccessful split-thickness grafts of lower limb ulcers. The patient's difficult-to-heal wounds made her an excellent candidate for treatment with tissue-engineered skin. At 10 months of age, this was applied to her previously nonhealing wounds. The tissue-engineered skin induced rapid healing of the patient's chronic amputation stump ulcers and provided her with substantial pain relief. In conclusion, tissue-engineered skin appears to be a potential beneficial treatment for chronic wounds in children with nonhealing amputation stumps.

Mucocutaneous pigmented macule as a result of zinc deposition.

BACKGROUND: Mucocutaneous depositions of various metals such as silver, lead, gold, arsenic, mercury, iron, and bismuth have been previously published. Heavy metal deposition typically occurs in the setting of either prolonged topical application to intact skin, topical application to eroded or ulcerated skin, as a result of either parenteral administration, or due to penetrating traumatic exposure. METHOD: We report a unique case of mucocutaneous pigmentation occurring in a snow skier after topical application of a zinc-containing sunblock. Formalin-fixed paraffin-embedded tissue was utilized for electron microscopy. RESULT: Backscatter electron imaging and energy dispersive spectroscopy revealed that the dominant metal present was zinc. CONCLUSIONS: Mucocutaneous deposition of metals is enhanced by damage to the surface epithelium. Metal-containing topical agents, although commonly used, may rarely result in a permanent pigmentary alteration. We believe similar cases of mucocutaneous deposition of zinc exist; however, as these may be currently misdiagnosed as amalgam tattoos, the true incidence of this disorder is presently undefined.

Localized scleroderma or morphea?

Morphea is a frequently mild, benign, and self-limiting skin disease with a less than 1% reported chance of progressing to systemic scleroderma. Morphea is a sufficient and less terrifying name for these disorders than localized scleroderma.

Evaluation of feedback-reduction algorithms for hearing aids.

Three adaptive feedback-reduction algorithms were implemented in a laboratory-based digital hearing aid system and evaluated with dynamic feedback paths and hearing-impaired subjects. The evaluation included measurements of maximum stable gain and subjective quality ratings. The continuously adapting CNN algorithm (Closed-loop processing with No probe Noise) provided the best performance: 8.5 dB of added stable gain (ASG) relative to a reference algorithm averaged over all subjects, ears, and vent conditions. Two intermittently adapting algorithms, ONO (Open-loop with Noise when Oscillation detected) and ONQ (Open-loop with Noise when Quiet detected), provided an average of 5 dB of ASG. Subjects with more severe hearing losses received greater benefits: 13 dB average ASG for the CNN algorithm and 7-8 dB average ASG for the ONO and ONQ algorithms. These values are conservative estimates of ASG because the fitting procedure produced a frequency-gain characteristic that already included precautions against feedback. Speech quality ratings showed no substantial algorithm effect on pleasantness or intelligibility, although subjects informally expressed strong objections to the probe noise used by the ONO and ONQ algorithms. This objection was not reflected in the speech quality ratings because of limitations of the experimental procedure. The results clearly indicate that the CNN algorithm is the most promising choice for adaptive feedback reduction in hearing aids.

Evaluation of an adaptive beamforming method for hearing aids.

In this paper evaluations of a two-microphone adaptive beamforming system for hearing aids are presented. The system, based on the constrained adaptive beamformer described by Griffiths and Jim [IEEE Trans. Antennas Propag. AP-30, 27-34 (1982)], adapts to preserve target signals from straight ahead and to minimize jammer signals arriving from other directions. Modifications of the basic Griffiths-Jim algorithm are proposed to alleviate problems of target cancellation and misadjustment that arise in the presence of strong target signals. The evaluations employ both computer simulations and a real-time hardware implementation and are restricted to the case of a single jammer. Performance is measured by the spectrally weighted gain in the target-to-jammer ratio in the steady state. Results show that in environments with relatively little reverberation: (1) the modifications allow good performance even with misaligned arrays and high input target-to-jammer ratios; and (2) performance is better with a broadside array with 7-cm spacing between microphones than with a 26-cm broadside or a 7-cm endfire configuration. Performance degrades in reverberant environments; at the critical distance of a room, improvement with a practical system is limited to a few dB.

Upper airway obstruction secondary to acquired immunodeficiency syndrome-related Kaposi's sarcoma.

A 45-year-old man with a history of intravenous drug use presented with acute respiratory distress. A pulsus paradoxus of 42 mm Hg, accessory respiratory muscle use and stridor were present. Examination of the oropharynx revealed multiple 1 to 2 cm purple lesions of the gingiva and hard palate. A purple tumor mass in the posterior pharynx obstructed the view of the larynx. An emergency tracheostomy was performed resulting in hemorrhage into the respiratory tract. Autopsy revealed disseminated Kaposi's sarcoma and large blood clots in the trachea and main stem bronchus. This case illustrates the occurrence of life threatening involvement of the upper aerodigestive tract with Kaposi's sarcoma and hemorrhagic complications resulting from surgical manipulation.