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Biomedical subjects

Y M Wong

Publications and source records attributed to Y M Wong.

14 recordsLinked to original sources
PubMed2001

The changing nature of elective laparoscopic surgery: a review over a 7 year period in a reproductive surgery unit.

There was a significant increase in the number of laparoscopic procedures performed in the Reproductive and Surgery Unit at the Jessop Hospital for Women over the 7 year period from 1991 to 1997. The three most common procedures were adhesiolysis/salpingo-ovariolysis, treatment of endometriosis and ovarian drilling, which together constituted over 80% of all cases. The duration of surgery and the complexity of the cases gradually increased with time. The determinants of patients staying overnight after laparoscopic surgery in decreasing order of importance were: (i) whether they had undergone surgery in the morning or in the afternoon; (ii) the operating time; and (iii) the number of entry ports used. Most (75%) of the laparoscopic procedures were performed or supervised directly by a consultant. In this study period the major complication rate was 0.7%.

Elective Surgical Procedures↗
PubMed1998

The effects of carotid endarterectomy on ocular haemodynamics.

PURPOSE: To determine the profile of blood flow velocities and resistive indices in the ocular vessels of patients with atherosclerotic carotid disease and characterise the effect of endarterectomy on these parameters. METHODS: Following a preliminary study on healthy volunteers, ophthalmic colour Doppler ultrasound examinations were performed on 27 male and 11 female patients with carotid disease. These measurements were compared with central retinal artery perfusion pressures and intraoperative internal carotid artery stump pressures. RESULTS: Significant changes were seen on the endarterectomised side. The peak systolic velocity in the ophthalmic artery, and resistive indices in the ophthalmic artery, central retinal artery and nasal posterior ciliary artery, rose from pre-operative values. No correlation between colour Doppler ultrasound measurements and intraoperative internal carotid artery stump pressures was present. When compared with ophthalmodynamometry readings, a relationship was noted with maximum velocities in the central retinal vein. CONCLUSION: Carotid endarterectomy alters the haemodynamics in selected vessels of the ocular circulation as measured by colour Doppler ultrasound, but more work is required to determine the clinical utility of this investigative modality.

Adult↗
PubMed1997

Elective neck dissection versus observation in the treatment of early oral tongue carcinoma.

BACKGROUND: The aim of the present review is to evaluate the results of elective neck dissection and "watchful waiting" in the surgical treatment of stages I and II squamous cell carcinoma of oral tongue. METHODS: This is a retrospective study of patients with surgical treatment between January 1980 and December 1994. RESULTS: There were 63 patients including those with 34 T1 and 29 T2 carcinoma. The first sites of tumor recurrence were 5 (8%) local, 17 (27%) regional, 2 (3%) distant, 1 (2%) locoregional, and 1 (2%) both regional and distant. Of the 30 NO neck patients who had no elective neck dissection, the regional recurrence rate was 47%, and eventually 23% died of tumor related to regional recurrence. Elective neck dissection significantly reduced the regional recurrence rate to 9% and also significantly reduced the regional recurrence related mortality to 3%. Elective neck dissection also increased the 5-year disease-free actuarial survival rate to 86% compared with 55% for "watchful waiting." CONCLUSIONS: Regional recurrence was the most common cause of failure after surgical treatment of oral tongue carcinoma. Elective neck dissection significantly reduced mortality due to regional recurrence and also increased the overall survival. There was no significant difference between elective radical neck dissection and selective I, II, and III neck dissection in the improvement of treatment results. This retrospective study suggests that elective selective I, II, III neck dissection is a treatment strategy of choice for stages I and II carcinoma of the oral tongue. A prospective randomized study is worthwhile to further evaluate the benefit of elective neck dissection in the treatment of early carcinoma of the tongue.

Adult↗
PubMed1992

A two-step alignment method for 3D computer-aided reconstruction based on fiducial markers and applied to mouse embryonic hearts.

An accurate three dimensional computer reconstruction of microscopic biological objects or distribution of molecules identified on serial sections must solve two major problems: 1) the alignment of sections using adequate extrinsic references (fiducial markers); 2) the impossibility of observing these references and the cellular or molecular structures in the microscope at the same magnification. To provide extrinsic references for objects embedded in soft media, we have modified and simplified the charcoal-paraffin method described by Langemeijer and Simons (1973). It consists of drilling three or four small holes into the paraffin block, sealing this block at the extremity of a glass holder and, from the other extremity of the holder attached to a rubber hose, aspirating a liquefied mixture of charcoal-paraffin to fill these cylindrical holes. An alignment procedure was developed using serial sections of mouse embryonic hearts with bromodeoxyuridine-labelled DNA synthesizing cells. From each fourth section, two sets of contours have been drawn and digitized: 1) at low magnification (about 40x), embryo body wall, heart, neural tube and extrinsic reference marks (black dots); 2) at higher magnification (240-300x): heart contours alone (without extrinsic references, but with individual labelled cells). Different operations of the computer-aided alignment, as well as checking of results by inverse alignment, are described in detail. This two-step alignment method offers a practical, efficient compromise between: a) purely subjective alignment based only on tissular landmarks interpreted by the operator; b) ideal perfect alignment based not only on adequate references, but on computerized correction of section deformation, as well.

Animals↗
PubMed1989

Rapid epithelial restitution of human and rabbit colonic mucosa.

Rapid epithelial restitution is now considered one of the primary defense mechanisms of the stomach and duodenum. Because there is currently no evidence as to whether restitution occurs in human tissue, this study examined human and rabbit colonic mucosa after superficial injury and monitored the potential difference, alkaline flux, and speed and mechanisms of mucosal restitution as observed with light and electron microscopy. Luminal exposure of the in vivo rabbit colon to 100 mM HCl for 5 min or the in vitro human colon to 10 mM HCl for 10 min caused superficial mucosal injury to 76% of the epithelial surface in the rabbit and 95% in the human. The necrotic epithelial cells detached in sheets from the intact basal lamina and formed a protective mucoid layer. Morphologic evidence of restitution occurred within 15 min after injury in the rabbit and 30 min in the human, as viable nongoblet cells projected lamellipodia and migrated over the denuded basal lamina at a speed of approximately 2 microns/min. One hour after damage 61% of the mucosal surface was still damaged in the rabbit, and 86% of the human mucosal surface was damaged after 2 h. In the following 60 min restitution progressed rapidly, so that only 10% of the surface remained unrepaired in the rabbit after 2 h and 19% in the human after 3 h. Small areas with deeper injury did not repair until 5 h after damage. The potential difference dropped after mucosal injury and did not recover despite morphologic repair. Rapid epithelial restitution is considered to be a basic defense mechanism of the gastrointestinal mucosa that is obviously not necessarily related to the presence of an acidic environment in the stomach or duodenum.

Animals↗
PubMed1983

Computer reconstruction of serial sections.

A computer graphics system is described which reconstructs three-dimensional images from serial sectional data. Microscopic sectional tracings are first digitized and coded with a microcomputer (APPLE II-Plus). The data are transferred to a main frame facility for reconstruction and the final result is displayed on a high-resolution color monitor (Hewlett-Packard 9845C). Depth cueing of the image is enhanced by edge ribboning and area filling. The system is very simple to operate and yet flexible enough to allow selective portions of the tissue sample to be reconstructed and displayed in various orientations.

Animals↗
PubMed1977

Vaginal administration of a single dose of 16, 16 dimethyl prostaglandin E2 p-benzaldehyde semicarbazone ester for pre-operative cervical dilatation in first trimester nulliparae.

A single pessary containing 0-5 mg 16, 16 dimethyl prostaglandin E2 p-benzaldehyde semicarbazone ester was used for cervical dilatation prior to vacuum aspiration in 124 first trimester nulliparae. Five hours after prostaglandin administration the cervix had dilated to 8 mm or more in 87 patients (70 per cent). The uterus was evacuated in these patients without mechanical dilatation of the cervix. In the remaining 37 patients the cervix had become soft and dilated 5 to 7 mm and further mechanical dilatation could be carried out easily. Side effects were minor and included vomiting in two patients, diarrhoea in one and transient pyrexia in two patients. There were no complications and no damage to the cervix or uterus during evacuation.

Abortion, Induced↗
PubMed1977

Sterilization failures in Singapore: an examination of ligation techniques and failure rates.

The University Department of Obstetrics and Gynecology, Kandang Kerbau Hospital in Singapore, initiated a study in early 1974 of failure rates for various methods of sterilization and the factors responsible for the failures. During the period January 1974 to March 1976, 51 cases of first pregnancy following ligation were discovered. Cumulative failure rates at 24 months were 0.34 per 100 women for abdominal sterilization, 1.67 for culdoscopic, 3.12 for vaginal, and 4.49 for laparoscopic procedures. Findings for 35 patients who underwent religation showed that recanalization and the establishment of a fistulous opening caused the majority of failures. Clearly, more effective methods of tubal occlusion in sterilization are needed.

Abdomen↗