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Biomedical subjects

H S Chan

Publications and source records attributed to H S Chan.

150 records · Page 9Linked to original sources
PubMedDate not supplied

Color Doppler imaging for vocal cord palsy.

BACKGROUND: Conventional techniques of laryngoscopy for vocal cord palsy can sometimes be difficult or impossible to perform, and B-mode real-time ultrasonography has been previously reported by the authors to be helpful in these situations. In some cases, however, B-mode ultrasonography can be inconclusive. We investigated whether color Doppler imaging can significantly improve vocal cord examination in these cases. METHOD: Ten normal volunteers were examined using the Acuson 128XP/5 with a 7-MHz L7384 linear transducer. The thyroid cartilage was used as an acoustic window. Several distinct color flow patterns were observed with the subjects breathing quietly at rest, at the start of vocalization, and in prolonged phonation. Eight patients with hoarseness of voice were then examined by two separate observers in a double-blinded fashion. The first observer performed B-mode ultrasonography and color Doppler imaging, while the second observer performed indirect laryngoscopy and direct fiberoptic laryngoscopy. RESULTS: Laryngoscopy was used as the standard for comparison. B-mode real-time ultrasonography correctly identified vocal cord palsy in three patients and normal vocal cords in one. The remaining four patients were reported as equivocal or normal. Color Doppler imaging correctly identified the problem in all eight patients. CONCLUSION: Color Doppler imaging for vocal cord examination is more sensitive than B-mode real-time ultrasonography, and seems to be as accurate as laryngoscopy in determining vocal cord palsy or paresis.

Adult↗
PubMedDate not supplied

Endodermal sinus tumor of the nasopharynx and previous mature congenital teratoma.

Congenital teratoma of the nasopharynx is a rare tumor that has shown consistently benign behavior. In contrast, endodermal sinus tumor, even more unusual nasopharyngeal germ cell tumor, displays consistently aggressive behavior with most reports documenting early death of the patient. We report the clinicopathological features of a case of endodermal sinus tumor of the nasopharynx that developed in a 3-year-old girl who had a mature teratoma excised from the same site in the neonatal period. Local recurrence of the endodermal sinus tumor was followed by disseminated disease and death within 18 months.

Child, Preschool↗
PubMedDate not supplied

Chemosensitivity and multidrug resistance to antineoplastic drugs in retinoblastoma cell lines.

Chemosensivity testing in 11 retinoblastoma (RB) cell lines identified five tumors showing cross-resistance to plant alkaloids, alkylating agents, anthracycline antibiotics, and antimetabolites, suggestive of the multidrug-resistant (MDR) phenotype described in other tumors. Only two tumors had been clinically exposed to chemotherapy, and both showed MDR. All RB tumors were resistant to clinically achievable concentrations of methotrexate and hydrocortisone, and only sensitive to cytosine arabinoside. These results provide a rational basis on which to develop new chemotherapeutic strategies for the treatment of RB.

Antineoplastic Agents↗