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Biomedical subjects

K F Kevorkian

Publications and source records attributed to K F Kevorkian.

6 recordsLinked to original sources
PubMed1998

Functional differences between the two bellies of the cricothyroid muscle.

The contraction of the cricothyroid (CT) muscle, which results in a decrease in the distance between the thyroid and cricoid cartilages, is considered to be the main factor in lengthening the vocal folds. This is achieved by rotation of the CT joint. The CT muscle is composed of two distinct bellies, the pars recta and the pars obliqua. The function of each subunit is not clearly understood, although it is believed that they act differently because their fibers run in different directions. To clarify the function of the two bellies in phonation, the fundamental frequency (F0), vocal intensity, subglottic pressure, vocal fold length, and CT distance were measured using an in vivo canine laryngeal model. On the basis of these measurements, we demonstrated that the two bellies are varied in their effect on raising the pitch, rotation, and forward translation of the CT joint. The stimulation of the pars recta nerve resulted in a greater increase in the F0 value compared with that of pars obliqua. The combined activity of the pars recta and pars obliqua is important in adjustment of the vocal fold length. The CT approximations directed parallel to the pars recta and pars obliqua simultaneously were more effective in elevation of the pitch than the approximation placed parallel to the pars recta only. This finding may be clinically significant with regard to CT approximation thyroplasty in human trails.

Analysis of Variance↗
PubMed1997

The role of strap muscles in phonation--in vivo canine laryngeal model.

In spite of the presumed importance of the strap muscles on laryngeal valving and speech production, there is little research concerning the physiological role and the functional differences among the strap muscles. Generally, the strap muscles have been shown to cause a decrease in the fundamental frequency (F0) of phonation during contraction. In this study, an in vivo canine laryngeal model was used to show the effects of strap muscles on the laryngeal function by measuring the F0, subglottic pressure, vocal intensity, vocal fold length, cricothyroid distance, and vertical laryngeal movement. Results demonstrated that the contraction of sternohyoid and sternothyroid muscles corresponded to a rise in subglottic pressure, shortened cricothyroid distance, lengthened vocal fold, and raised F0 and vocal intensity. The thyrohyoid muscle corresponded to lowered subglottic pressure, widened cricothyroid distance, shortened vocal fold, and lowered F0 and vocal intensity. We postulate that the mechanism of altering F0 and other variables after stimulation of the strap muscles is due to the effects of laryngotracheal pulling, upward or downward, and laryngotracheal forward bending, by the external forces during strap muscle contraction.

Animals↗
PubMed1997

Extended canine laryngeal preservation for transplantation.

The goal of successfully transplanting the larynx has motivated researchers since the 1960s. Early laryngeal transplant techniques limited the donor larynx to 45 minutes of ischemia. In this study, a method of prolonged laryngeal preservation is employed in three canines. In vivo cold laryngeal perfusion with University of Wisconsin Solution (UWS) was performed. The larynx was removed and placed into cold storage in 4 degrees C UWS. After 24 hours of storage, the same canines underwent laryngeal reimplantation. The animals were sacrificed 7 days after reimplantation. No evidence of necrosis or vascular insufficiency was identified histologically. The results indicate that canine larynges can be successfully reimplanted after 24 hours of preservation. Future studies will assess the application of this technique to laryngeal transplantation.

Animals↗
PubMed1995

Cryptococcosis presenting as a neck mass.

A rare case of cryptococcal infection presenting as a neck mass in an otherwise healthy individual is reported. The mass resulted in lytic destruction of portions of the cervical vertebrae and produced a focal neurologic deficit in one of the upper extremities. Although other lesions in the skull, femur, and humerus were identified, no involvement of the lungs or central nervous system could be detected. The patient was initially treated with amphotericin B and flucytosine, but eventually also required fluconazole and surgical debridement for complete resolution of the infection. The diagnosis, treatment, and manifestations of cryptococcosis in the head and neck are discussed.

Biopsy↗