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Biomedical subjects

David W Kim

Publications and source records attributed to David W Kim.

At least 19 recordsLinked to original sources
PubMed2006

Total synthesis and biological evaluation of halipeptins A and D and analogues.

The marine-derived halipeptins A (1a) and D (1d) and their analogues 3a, 3d and 4a, 4d were synthesized starting from building blocks 10, 13, 14a or 14d, 15, and 16. The first strategy for assembling the building blocks, involving a macrolactamization reaction to form the 16-membered ring hydroxy thioamide 52d as a precursor, furnished the epi-isoleucine analogue (4d) of halipeptin D, whereas a second approach involving thiazoline formation prior to macrolactamization led to a mixture of halipeptins A (1a) and D (1d) and their analogues 3a, 3d (epimers at the indicated site) and 4a, 4d (epimers at the indicated site). The same route starting with D-Ala resulted in the exclusive formation of the epimeric halipeptin D analogue 3d. The synthesized halipeptins, together with the previously constructed oxazoline analogues 5d and 6d, were subjected to biological evaluation revealing anti-inflammatory properties for 1a, 1d, and 6d while being noncytotoxic against human colon cancer cells (HCT-116).

Anti-Infective Agents↗
PubMed2006

Management of naso-septal L-strut deformities.

Deformities of the naso-septal L-strut create functional and aesthetic problems, such as the twisted nose, the malpositioned tip, the saddle deformity, and internal valve insufficiency. The surgeon must approach these problems with three principles. First, in certain situations, the L-strut must be modified. Second, the L-strut must be structurally stable to support to the nose. Third, the position of the L-strut and its relationship to neighboring structures will determine the changes in nasal form and function. The current article focuses on two common types of deformities of the septal L-strut: deviation and collapse. Mild deviations are addressed through repositioning or camouflaging techniques. Moderate deviations are treated with cartilage-bolstering techniques. Severe deviations are resected and reconstructed with cartilage grafts. Dorsal septal reconstruction or onlay grafting treats collapse. Caudal septal reconstruction and tip-supporting grafts address nasal tip collapse. Total septal loss or collapse requires construction of a new L-strut. These techniques should maintain support to the nose while improving nasal form and function.

Cartilage↗
PubMed2006

Metrics of nasal tip rotation: a comparative analysis.

OBJECTIVE: We introduce a new metric for measuring nasal tip rotation, the "columellar facial angle." The present study aimed to determine the degree of correlation of the nasolabial angle, the nostril axis, and the columellar-facial angle as metrics of nasal tip rotation in healthy volunteers. The study also aimed to identify any nasal or facial features unrelated to tip position, which consistently altered these values. METHODS: Lateral photographs in the Frankfort horizontal plane were taken of 100 volunteers. Measurements of tip rotation were then calculated for each model using three different methods: nasolabial angle, nostril axis, and columellar-facial angle. Data were analyzed for degree of correlation of the three values for all models. Facial features in those subjects with low correlation between measurement methods were analyzed. RESULTS: For all grouped data, both the nasolabial angle and the nostril axis showed moderate correlations with columellar facial angle but no correlation with each other. Individual subjects whose measurements did not correlate tended to display certain anatomic features: premaxillary deficiency, premaxillary excess, sloped upper lips, or vertical malposition of the nostrils. CONCLUSIONS: No one method of measurement of nasal tip rotation is reliable for all patients. Certain nasal and facial features are likely to alter these values. Of the three measurement methods presented, the columellar-facial angle is most likely to yield consistent measurements of nasal tip rotation.

Face↗
PubMed2005

Total synthesis of halipeptins: isolation of halipeptin D and synthesis of oxazoline halipeptin analogues.

The isolation from the marine sponge Leiosella cf. arenifibrosa and structural elucidation of halipeptin D (5), a relative of the previously isolated halipeptins A-C (1-3), is described along with the total synthesis of a number of oxazoline analogues (7 a-d and epi-7 c-d). The developed synthetic strategy provides a flexible entry into the various isomers of the polyketide domain of the halipeptins and improvises for a late stage construction of the oxazoline ring after a macrolactamization process which secures the required macrocycle.

Animals↗
PubMed2005

Current concepts in cheek reconstruction.

For cutaneous cheek defects, the reconstructive surgeon should strive to optimize tissue match and scar camouflage while minimizing the distortion to neighboring facial landmarks. The surgeon must have an intimate understanding of the local anatomy and must be able to use the appropriate flap for the given characteristics of each defect and patient. Knowledge of several types of flaps and versatility in modifying these flaps from their "textbook" geometry are required. This article highlights an approach to local flap reconstruction with a review of flap modification for particular situations.

Aged↗
PubMed2005

Upper blepharoplasty in the Asian eyelid.

Upper eyelid blepharoplasty is a major component of cosmetic surgery in the Asian face. The complicated and variable anatomy of the Asian upper eyelid is reviewed, stressing the major differences between Asian and Caucasian eyes. The authors' preferred surgery for the creation of a double eyelid is discussed, including the preoperative assessment, intraoperative maneuvers, and laser techniques. The article concludes with a discussion of the complications specifically related to Asian blepharoplasty and strategies to avoid them.

Asian People↗
PubMed2005

A novel intranasal stent for functional rhinoplasty and nostril stenosis.

OBJECTIVES/HYPOTHESIS: The surgical correction of nostril stenosis and external nasal valve collapse typically involves the addition of tissue to widen and strengthen these areas. However, over the ensuing months, postoperative scar contracture may act to reverse the surgical modifications. This study aimed to determine the safety and efficacy of the use of nasal stents fashioned from a nasopharyngeal airway tube to prevent postoperative contracture at these sites. STUDY DESIGN: Retrospective review of six patients who underwent functional rhinoplasty with alar batten graft placement for nasal valve collapse and one patient who underwent composite graft repair of unilateral nostril stenosis. METHODS: Patients completed a survey inquiring about the ease of use, discomfort, presence of infection, and ability to breathe with these nasal stents. Patients also completed the NOSE (nasal obstruction symptom evaluation) instrument to compare their overall level of preoperative and postoperative nasal breathing. The functional rhinoplasty patients were examined for degree of dynamic airway nasal wall collapse and position of the lateral nasal wall on intranasal examination. RESULTS: Six of seven patients overall reported no to minimal discomfort, easy application, and no to minimal obstruction of nasal breathing with the use of the stents. One patient reported difficulty with application. Preoperative NOSE scores averaged 67.1 (SD 10.4), 18.6 (SD 14.6) at the time of splint removal, and 21.4 (SD 15.2) at 3 months after stent removal. Paired t test analysis showed significant differences between the NOSE scores preoperatively as compared with the time of splint removal (P = .0002) or 3 months after splint removal (P = .0003). All patients demonstrated a significant reduction of lateral nasal wall collapse with inspiration on physical examination. CONCLUSIONS: The use of nasal stents made from nasopharyngeal airway tubes is a safe, convenient, and economic treatment for the prevention of contracture after surgical correction of nostril stenosis or nasal valve insufficiency.

Constriction, Pathologic↗
PubMed2005

Biomechanical strength of human nasal septal lining: comparison of the constituent layers.

OBJECTIVE/HYPOTHESIS: Nasal septal perforation is a common complication following surgery involving the nasal septum. Septoplasty, septorhinoplasty, and submucosal resection may result in the inadvertent resection of perichondrium, which may predispose the patient to septal perforations. STUDY DESIGN: Controlled human cadaver study testing the biomechanical strength of the constituent layers of nasal septal lining. METHODS: Uniform samples of nasal septal mucosa, perichondrium, and a composite of both layers were obtained from five fresh human cadavers. The mechanical tensile strength of these layers was evaluated and compared with the Instron 4301 Mechanical Testing System (Canton, MA). RESULTS: Mixed-effects regression analysis demonstrated a significant difference in the tensile strength of the three groups (mean values +/- SD: mucosa, 662 +/- 308 g; perichondrium, 1370 +/- 798 g; composite, 2340 +/- 1252 g). All three pairwise comparisons among the three groups showed a significant difference in tensile strength. CONCLUSION: The perichondrial layer imparts the majority of the biomechanical strength to septal lining. Lining flaps containing both perichondrium and mucosa are stronger than flaps with either perichondrium or mucosa alone. Dissection in the subperichondrial plane during septal surgery provides a stronger septal flap and may prevent the development of nasal septal perforation during nasal surgery.

Biomechanical Phenomena↗
PubMed2004

Management of posttraumatic nasal deformities: the crooked nose and the saddle nose.

The crooked nose deformity and the saddle nose deformity represent two of the most challenging complications of nasal trauma. Optimal management requires careful preoperative analysis and thoughtful surgical planning. The surgeon must make the mental and philosophical commitment to address the difficult cosmetic components and the functional problems related to these deformities. Because these conditions result from disruptions of the nasal septum, their surgical correction mandates use of techniques that modify the septum, and they might require reconstruction of the sacrosanct dorsal-caudal strut. By understanding the three-dimensional anatomy of this L-shaped strut, how its relationship to the other structural components of the nose determines external nasal contour, and the techniques available to stabilize this structure into an optimal position, the surgeon can correct these difficult cosmetic problems effectively while maintaining the overall structural and functional integrity of the nose.

Esthetics↗
PubMed2003

Total synthesis and biological evaluation of (-)apicularen A and analogues thereof.

Apicularen A (1) and related benzolactone acylenamines belong to a growing class of novel natural products possessing highly cytotoxic properties. The challenging structure of 1 includes a 10-membered macrolactone ring, a tetrahydropyran system, an o,m-substituted phenol and a doubly unsaturated acyl group attached on the side chain enamine functionality. The total synthesis of apicularen A described herein involves a strategy equivalent to its proposed biosynthesis and entails a reiterative two-step procedure featuring allylation and ozonolytic cleavage to grow the molecule's chain by one acetate unit at a time. The developed synthetic technology was applied to the construction of a series of apicularen A analogues whose biological evaluation established a set of structure-activity relationships in this new area of potential importance in cancer chemotherapy.

Amines↗
PubMed2003

Botulinum toxin A for the treatment of lateral periorbital rhytids.

The lateral periorbital area represents one of the earliest and most bothersome facial stigmata of aging. Although traditional techniques have had limited success in treating the static cutaneous component to rhytid formation in this region, they have been largely unsuccessful in addressing the dynamic hyperkinetic lines that are created by the activity of the lateral orbicularis oculi muscle. Botox A injection represents a safe and reproducible technique to selectively denervate muscle activity in this troublesome area. This minimally invasive technique has led to significant improvement of periorbital lines, either when used as a single agent or in combination with other methods (Fig. 3). As more experience is gained with this toxin, as well as other Botox serotypes, continued progress is likely to occur in this area, as well as in other facial regions.

Botulinum Toxins, Type A↗
PubMedDate not supplied

Concentric and eccentric carved costal cartilage: a comparison of warping.

OBJECTIVE: To determine if a systematic, concentric graft-carving technique results in less warping than eccentric carving. METHODS: Costal cartilage from ribs 3 through 9 were harvested from fresh human cadavers. Concentric dorsal grafts were carved from cartilage obtained from one side of the cadaver (n = 7) and eccentric grafts were carved from the opposite side (n = 11). After carving, grafts were placed in saline sponges (isotonic sodium chloride) for 1 hour, and photographs were then taken from a lateral and a frontal view. Identical photographs were taken after 2 weeks of incubation in saline (36.7 degrees C). The angle of curvature was measured from the photographs. RESULTS: More warping occurred in the eccentric group than the concentric group on lateral view at 1 hour (4.4 degrees vs 0.4 degrees; P<.001) and at 2 weeks (5.8 degrees vs 1.4 degrees; P = .003). Eccentric grafts progressively warped between the 1-hour and 2-week points. CONCLUSION: Meticulous concentric carving of costal cartilage grafts may minimize the complication of graft warping.

Cadaver↗