Biomedical subjects

C M Ho

Publications and source records attributed to C M Ho.

13 recordsLinked to original sources

PubMed1992

Pathological basis of surgery in the management of postradiotherapy cervical metastasis in nasopharyngeal carcinoma.

Radical neck dissection was performed on 43 patients with nasopharyngeal carcinoma in whom persistent or recurrent cervical metastasis developed after radiotherapy. The pathologic nature of the tumor in the cervical lymph nodes was studied with step serial sectioning of the entire radical neck dissection specimen at 3-mm intervals. In 70% of patients, more tumor-harboring lymph nodes were detected in the specimen when compared with clinical examination. The extensive behavior of the tumor in the cervical metastases was reflected by the presence of extracapsular spread in 70% of the lymph nodes and the existence of isolated clusters of tumor cells in 35% of the specimens studied. Tumor tissue lying in close proximity to the spinal accessory nerve was demonstrated in 27.5% of the specimens, and 72% of the tumor-bearing lymph nodes were located in the posterior triangle. Radical neck dissection is recommended as the salvage procedure for these patients.

Adult↗

PubMed1992

Automated solid models from serial section images.

A new method for creating unambiguous and complete boundary representation solid models with a hybrid polygonal/nonuniform rational B spline representation was developed and tested using computed tomography scans of the wrist. Polygon surface approximation was applied to a sequence of parallel planar outlines of individual bone elements in the wrist. An automated technique for the transformation of edge contours into solid models was implemented. This was performed using a custom batch file command sequence generator coupled to a commercially available mechanical computer-aided design and engineering software system known as I-DEAS (Structural Dynamics Research Corporation, Milford, OH). This transformation software allows the use of biomedical scan slice data with a solid modeler.

Carpal Bones↗

PubMed1992

Presence of Na+/Ca2+ exchange activity and its role in regulation of intracellular calcium concentration in bovine adrenal chromaffin cells.

The presence of a Na+/Ca2+ exchanger in bovine adrenal chromaffin cells was demonstrated by measuring the efflux of 45Ca2+ which had been preloaded into cells by a brief depolarization. The efflux of 45Ca2+ was dependent on extracellular Na+ (Na+o); 45Ca2+ efflux was significantly decreased by replacing Na+o with N-methylglucamine (NMG), or Li+. Replacement of Na+o by NMG increased the resting intracellular Ca2+ concentration ([Ca2+]i) of freshly isolated chromaffin cells. This could be reversed by adding Na+, suggesting that Na+/Ca2+ exchanger activity was involved in maintaining [Ca2+]i at its resting level. The initial rate of Na(+)-dependent [Ca2+]i recovery after Ca2+ loading by depolarization was dependent on the level of [Ca2+]i. There was an apparent linear relationship between the activity of the Na+/Ca2+ exchanger and [Ca2+]i both in the presence and absence of Na+o. When cells were treated with other stimuli, including 10 microM DMPP or 40 mM caffeine, the ability of the stimulated cells to decrease [Ca2+]i was significantly reduced upon replacing Na+o with NMG. Our data show that the Na+/Ca2+ exchanger is one of the major pathways for regulating [Ca2+]i in chromaffin cells in both resting and stimulated states.

Adrenal Medulla↗

PubMed1992

Treatment of neck nodes in oral cancer.

In a review of 98 patients who were operated upon for squamous oral cancer, a high proportion of them (48%) developed recurrence after a minimum follow-up of 2 years. Nodal status significantly affected the nodal recurrence rate and survival. For N0, N1, N3 tumours, the 2-year nodal recurrence-free rates were 79, 83, 18%, and the 2-year survival rates were 58, 59 and 10%. For small tumours with N0 neck, the group with elective neck dissection and the observed group did not have statistically different nodal recurrence-free rate and overall survival. The 2-year nodal recurrence-free rate was 92% versus 77% (P value > 0.3) and the 2-year survival rate was 56% versus 72% (P value > 0.6). In patients with N1 neck, radical neck dissection was reasonably effective in controlling neck metastasis. Radical neck dissection in an attempt to treat fixed neck nodes (N3) was not successful in controlling the neck disease.

Adult↗

PubMed1992

Pattern of ovarian tumours among Malaysian women at General Hospital, Kuala Lumpur.

The objective of this two year retrospective study is to find out the pattern of ovarian tumours among Malaysian women. A total of 280 cases were reviewed. Of these 193 were benign, 81 were malignant and six cases belonged to borderline malignancy. In the general population, equal distribution of serous and mucinous tumours among the benign (15.4%) and malignant (4.3%) types is quite a striking feature. The teratomas were the commonest benign tumour among the Malays and Chinese. Serous cystadenomas were the commonest among the Indians. The Malays had higher incidence of malignant epithelial tumours whereas the Chinese had a higher incidence of metastatic and germ cell tumours. Endometroid tumours occurred from an earlier age of thirty years. There was a preponderance of mucinous tumours among the borderline variety.

Adolescent↗

PubMed1992

Staging of cervical cancer: comparison between magnetic resonance imaging, computed tomography and pelvic examination under anesthesia.

A prospective study was undertaken to compare magnetic resonance imaging (MRI) with computed tomography (CT) and examination under anesthesia (EUA) in staging cervical carcinoma, with special emphasis on parametrial status. Twenty patients with carcinoma of the cervix, in whom the extent of the disease was surgically confirmed, were analyzed by MRI, CT and EUA. The tumor size estimated by MRI correlated well (r = 0.79, p < 0.001) with those obtained by histopathologic measurement of the surgical specimen. Neither clinical examination nor CT could precisely estimate tumor size. The overall accuracy rate of MRI in staging carcinoma of the cervix was 75%, compared with 32% for CT staging and 55% for clinical staging. The accuracy rate of these modalities for parametrial status was 90% for MRI, 55% for CT and 82.5% for EUA. MRI accurately excluded all 20 patients with pelvic side wall, bladder and rectal involvement. In conclusion, MRI is superior to CT and EUA in assessment of the parametrium (90% vs 55% vs 82.5%, p < 0.005). From MRI, tumor size can be estimated precisely. Although a larger scale study comparing MRI and CT is needed to determine their roles, both should help in the diagnosis and selection of proper treatment for cervical carcinoma. Our preliminary report agrees with previous reports that MRI is promising and indispensable. MRI should be routinely used in conjunction with clinical staging to determine appropriate therapy in patients with cervical carcinoma.

Adult↗

PubMed1991

Tracheostomal stenosis after immediate tracheoesophageal puncture.

The incidence of tracheostomal stenosis in a group of patients after total laryngectomy with or without pharyngectomy plus immediate tracheoesophageal or tracheogastric puncture was compared with that of a control group without puncture. The stenosis rate of the puncture group was significantly higher than that of the control group (19% vs 6%). The other probable etiologic factors for stomal stricture were similar in both groups. Analysis of the risk factors in the puncture group suggested a higher tendency of stenosis in females (43% vs 16%) and in patients receiving postoperative radiotherapy (29% vs 14%), although the difference failed to reach statistical significance.

Adult↗

PubMed1991

Radical neck dissection in nasopharyngeal carcinoma.

We report a series of 37 patients who had radical neck dissection for residual or recurrent lymph node metastasis from nasopharyngeal carcinoma after radiotherapy. The operation was performed despite high doses of pre-operative radiotherapy. There was no operative mortality and the morbidity was 13% (2 prolonged chylous drainage, 3 sloughing of neck flap). The risk of sloughing of neck flap was significantly related to previous lymph node biopsy, which should be avoided if at all possible. In 35% of patients, the lymph node was densely adherent to neighbouring structures. In the 28 patients who had single lymph node clinically, 29% had multiple neck node involvement noted during operation; another 14% were documented only on histological examination. Radical neck dissection rather than excision alone is justified for the clinically solitary lymph node.

Adult↗

PubMed1990

Cavity search: an algorithm for the isolation and display of cavity-like binding regions.

A set of algorithms designed to enhance the display of protein binding cavities is presented. These algorithms, collectively entitled CAVITY SEARCH, allow the user to isolate and fully define the extent of a particular cavity. Solid modeling techniques are employed to produce a detailed cast of the active site region, which can then be color-coded to show both electrostatic and steric interactions between the protein cavity and a bound ligand.

Algorithms↗

PubMed1977

Epidemiological and serological study of scrub typhus among Chinese military in the Pescadores islands of Taiwan.

An outbreak of 69 cases of scrub typhus occurred among Chinese military personnel stationed in the Pescadores Islands, Taiwan Province, Republic of China between May and November 1975. A retrospective epidemiological study of this outbreak indicated that military personnel over 40 were more likely to have scrub typhus than those under 40. High risk groups included the Garrison Force (home guard), anti-aircraft gunners and infantry and armoured units stationed at Hsing-jen. The onset of symptoms in 69% occurred within one year of residence in the Pescadores. The clinical course of scrub typhus and the serological response to infection were also studied. Eschar formation, fever, headache chills and lymph node enlargement were the predominant clinical manifestations noted. The indirect immunofluorescent antibody test (IFAT) demonstrated diagnostic (four-fold) rises in antibody titres to Rickettsia tsutsugamushi reference strains in 36 of 41 paired sera tested. 11 of 19 patients from whom only single sera were obtained had IFA titres presumptive of scrub typhus (greater than or equal to 1:160). Of 19 patients experiencing possible primary infections, 13 (68%) responded with antibodies directed against more than one reference strain of R. tsutsugamushi. These results suggest that several antigenically diverse strains of R. tsutsugamushi may be active in the Pescadores.

Animals↗

PubMed1977

Indirect immunofluorescence antibodies in natural and acquired Rickettsia tsutsugamushi infections of Philippine rodents.

Antibodies against Rickettsia tsutsugamushi detected by the indirect fluorescent-antibody test (IFAT) were present in most rats trapped from a human focus of scrub typhus in the Philippines. Rickettsiae were isolated only from rats with positive IFATs. Naturally acquired antibodies persisted for at least 11 months, and antibodies resulting from experimental infections of rats persisted for at least 7 months. A common Philippine rodent, Rattus mindanensis, tolerated experimental infections with both local and standard Karp strains of R. tsutsugamushi, and such infections always produced a positive IFAT.

Animals↗

PubMed1977

Failure of cyclophosphamide to significantly enhance isolation of Rickettsia tsutsugamushi from wild Philippine rats.

Treatment of wild rats from a known scrub typhus focus in the Philippines with cyclophosphamide did not significantly enhance the isolation rate of Rickettsia tsutsugamushi using mouse inoculation techniques. Similarly, cyclophosphamide treatment of mice inoculated with organs of wild rats did not increase the recovery of rickettsiae, and isolation of rickettsiae was about equal from biopsies obtained before and after immunosuppression of wild rats.

Animals↗

PubMedDate not supplied

Occult lymph node metastasis in small oral tongue cancers.

The need to treat the neck in patients with a small primary cancer in the tongue remains controversial. Twenty-eight patients with stage I or II oral tongue squamous carcinomas were retrospectively reviewed. They had not received previous treatment. The tongue primary was excised via the transoral route and the neck was observed closely during follow-up. Thirteen patients developed ipsilateral nodal metastases during follow-up, three of whom also had simultaneous recurrence at the primary site. An additional patient had recurrence at the primary site alone. The incidence of occult neck metastasis was 42% (10 of 24). No tumor-related death occurred in the group without nodal metastasis. The salvage rate after appearance of nodal metastasis was 30%. In oral tongue cancers, elective neck treatment should be considered regardless of a small primary and negative neck examination because of the high incidence of occult nodal metastasis and the poor outcome after salvage treatment.

Adult↗