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Biomedical subjects

E S Chan

Publications and source records attributed to E S Chan.

33 records · Page 2Linked to original sources
PubMed1999

The efficacy of collagen dermis membrane and fibrin on cultured epidermal graft using an athymic mouse model.

A human skin substitute consisting of human cultured keratinocytes, collagen dermis, and fibrin was evaluated in athymic mice. Eighty athymic mice were divided randomly into four groups. A 1.5x1.5-cm full-thickness wound defect was created on the back of each athymic mouse under anesthesia. These wounds were covered by sheets of cultured epidermal graft (group A), cultured epidermal graft with collagen dermis and fibrin (group B), cultured epidermal graft with collagen dermis (group C), or cultured epidermal graft with fibrin (group D). The grafts were secured and kept moist by specially designed saline gauze chambers. The take rates of the cultured graft with more than 50% of the wound covered were 65%, 15%, 50%, and 45% respectively. Group B had a significantly lower graft take rate, however the difference was not significant among groups A, C, and D. Light microscopy of biopsies of the grafted sites at 12 days showed complete epithelialization. The incidence of discharge from wound beds in groups A, B, C, and D was 0%, 15%, 15%, and 10% respectively. The results suggest that cultured cells are best grafted directly onto the wound bed or in combination with either a thin layer of collagen or fibrin but not both because the collagen dermal membrane and the fibrin together may impose too great a diffusion barrier for the cultured cell graft to become vascularized.

Animals↗
PubMed1999

Development and evaluation of a new composite Laserskin graft.

BACKGROUND: Tremendous effort has been made to improve the graft take rate of cultured epidermal autograph. The purpose of this study is to develop and evaluate a new composite Laserskin graft (CLSG) as a human skin substitute for wound resurfacing. METHODS: The seeding efficacy of cultured keratinocytes on plain Laserskin was compared with the 3T3 cell-seeded Laserskin and allogenic fibroblast-populated Laserskin. Three different types of CLSG, 2 cm in diameter each, were prepared and tested in rats. Type A CLSG consisted of proliferative allogenic rat fibroblasts on both sides of the Laserskin with autologous keratinocytes also on the upper side. Fibroblasts and keratinocytes were seeded only on the upper side of the Laserskin in type B CLSG. Keratinocytes alone were seeded on plain Laserskin in type C CLSG. Type B CLSG consisting of autologous keratinocytes and autologous dermal fibroblasts was tested on five selected wounds (5x5 cm each) of a patient with full-thickness burn. In another burn patient, type B CLSG consisting of autologous keratinocytes and allogenic dermal fibroblasts was grafted onto three wounds (5x5 cm each). RESULTS: The seeding efficacy of human keratinocytes on plain Laserskin increased from 75% to 95% when proliferative allogenic fibroblasts were grown as a feeder layer on the Laserskin. The seeding efficacy of rat keratinocytes increased from 36% to 88% in the presence of a proliferative allogenic fibroblast feeder layer, whereas human/rat keratinocytes had respective seeding efficacy of 98%/91% on Laserskin preseeded with mitomycin C-treated 3T3 cells. Skin biopsies of grafted type A CLSG on day 14 after grafting showed complete epithelialization without severe inflammation in 16 of 20 (80%) grafted surgical wounds in rats. There were eight (40%) and seven (35%) "takes" of the CLSG in types B and C, respectively. The infection rate in type B CLSG was two (10%). There was one (5%) infection in types A and C. The respective take rates on the two patients grafted with type B CLSG were 60% and 100%. CONCLUSION: The animal experiment and the preliminary clinical data showed that the CSLGs consisting of autologous keratinocytes and of autologous/allogenic fibroblasts are good human skin substitutes in terms of durability, biocompatibility, high seeding efficacy for keratinocytes, high graft take rate, and low infection rate.

3T3 Cells↗
PubMed1998

Burn injuries during paint thinner sniffing.

Thinner sniffing is popular among school children in Asian countries because it is readily available at low cost. Besides its toxicity to major organs, thinner inhalation is associated with various burn accidents. Four teenagers were admitted to the Burns Unit of the Prince of Wales Hospital over the period of 1996-1997. They sustained 3-25% TBSA flame burn and two of them had inhalation injuries as a result of the ignition of a cigarette during thinner sniffing. None of them had evidence of thinner intoxication as shown by blood tests. In the management of their acute burn injuries, their hidden social and family problems were explored. With the cooperation of different disciplines, early psychosocial intervention was given and their behavioral and psychological disturbances were successfully managed.

Adolescent↗
PubMed1998

Late complications of nasal augmentation using silicone implants.

Alloplastic nasal augmentation with silicone elastomer (Silastic) is popular in areas of Asia. Although the silicones are bio-inert, they have been implicated in a number of adverse reactions after implantation. We report our experience of three patients who presented with late complications after nasal augmentation using Silastic implants. The mechanisms of implant failure are proposed. It is advised that this material should only be used on an individual basis in carefully selected cases.

Adult↗
PubMed1998

Mammogram screening of Chinese women in Kwong Wah Hospital, Hong Kong.

The incidence of primary carcinoma of the breast in Hong Kong has been rising. A screening team including radiologists, breast surgeons, cytopathologists, a full-time gynaecologist and mammographers was set up at Kwong Wah Hospital. The screening method includes a clinical breast examination (CBE) and two-view mammography. The target age group is 40-70. A total of 13,033 women were screened from March 1993 to March 1995 and 8504 mammograms were performed. A double reading system was used, with an experienced mammographer as the first reader. The films were then read by radiologists and were reported. All abnormal films and normal films with palpable masses or clinical symptoms were reviewed in a weekly meeting. A total of 113 biopsies were performed including 86 stereotactic-guided fine needle aspirations (FNA) and 27 stereotactic-guided hook-wire biopsies. Four FNA showed malignant cells and another five showed suspicious cells. Eleven hook-wire biopsies showed carcinoma. The benign to malignant ratio of the hook-wire biopsies was 16:11 (< 1.5). The total number of carcinomas disclosed was 42, and 16 of these were not palpable. Four palpable tumours were not detected by mammography. The overall carcinoma of the breast detection rate was 4.94/1000, with a rate of 4.61/1000 for the 40-49-year age group and a rate of 6.46/1000 for the over 50 years of age group. The incidence of ductal carcinoma in situ plus T1 tumours was 2.82/1000.

Adult↗
PubMed1998

Madelung disease: distribution of cervical fat and preoperative findings at sonography, MR, and CT.

PURPOSE: Our goal was to document the distribution of excess fat in the neck and to determine the preoperative role of sonography, CT, and MR imaging in patients with Madelung disease. METHODS: Eight patients with Madelung disease were examined preoperatively with sonography, CT, and MR imaging of the neck, and the extent to which each technique provided answers to the surgeons' questions--such as distribution of fat, course of the major vessels within the fat, and presence of tracheal compression and nonlipomatous lesions--was studied. RESULTS: Excess fat was seen predominantly in the posterior part of the neck (eight patients), under the trapezius (eight patients) and sternomastoid (six patients) muscles, in the supraclavicular fossa (five patients), between the paraspinal muscles (five patients), in the anterior part of the neck (suprahyoid in seven patients and infrahyoid in three patients), in the superior mediastinum (three patients), and in the prevertebral space (two patients). Excess fat deposition was also seen in the pretracheal space (one patient), extrapleural space (two patients), and over the cheeks (one patient), sites previously not described. CONCLUSION: As a preoperative investigative tool for Madelung disease, both MR imaging and noncontrast CT provide the surgeon with adequate information; sonography is less helpful.

Adipose Tissue↗
PubMed1998

Carcinoma showing thymiclike differentiation (CASTLE tumor).

A 67-year-old woman had had a neck mass for 10 years, which recently increased in size. Sonographic, CT, and MR examinations showed a mass in the carotid and posterior spaces (triangle) extending from below the submandibular gland to the supraclavicular fossa, displacing the common carotid artery and the sternomastoid anteriorly. The mass was solid, noncalcified with lobulated outlines, hypoechoic on sonograms, of soft-tissue density on CT scans, isointense on T1-weighted MR images, hyperintense on T2-weighted MR images, and enhanced mildly after injection of contrast material on CT and MR studies. Histologic examination revealed a carcinoma showing thymiclike differentiation, a rare tumor of the neck and thyroid gland.

Aged↗
PubMed1980

The clinical and radiological features of the empty sella syndrome.

The importance of the empty sella syndrome has increased with recent interest in pituitary micro-adenomas, trans-sphenoidal hypophysectomy and computerised tomography. Four cases of the empty sella syndrome which illustrate the clinical and radiological features are reported, and the literature is reviewed. Headache, visual symptoms and endocrine disturbances are commonly found in association with the empty sella syndrome, and the coexistence of pituitary micro-adenomas is well recognised. Symmetrical ballooning of the sella turcica without changes in configuration is the typical finding with plain radiography, but occasionally more extensive destructive changes in the region of the pituitary fossa may occur. Provided that the correct angulation, collimation and level of cut are chosen, computerised tomography now may be used to make a definitive diagnosis, making air encephalography unnecessary.

Adenoma↗
PubMedDate not supplied

Boiling wax burn in mid-autumn festival in Hong Kong.

An unusual cause of burn, contact with boiling wax by children and adolescents during the annual mid-autumn festival in Hong Kong is presented. 57 patients who suffered from hot wax burn over the period 1986-1996 were admitted to the Burns Unit of the Prince of Wales Hospital. This special burn should be preventable by public education.

Adolescent↗
PubMedDate not supplied

A new system for the cultivation of keratinocytes on acellular human dermis with the use of fibrin glue and 3T3 feeder cells.

The growth of human keratinocytes on human acellular dermis in 4 different culture systems was compared. Epidermis was completely separated and removed from dermis after skin samples had been soaked in 0.1% trypsin at 4 degrees C for 1 week. Forty pieces of saline-washed dermis, 1 cm2 each, were randomized into 4 groups: in group A, human keratinocytes that had undergone 2 to 3 cell passages were seeded (30 x 10(4) cell/cm2) onto the dermis and sprayed with a thin layer of fibrin glue and proliferative 3T3 feeder cells that had been growing separately on the culture dish; in group B, the dermis was only sprayed with fibrin glue; in group C, the dermis was treated with 3T3 cells only; and in group D, the dermis was not sprayed with anything. The dermis samples in all groups were raised on a grid to provide an air-liquid culture system. Histology results of the composite grafts at 2 weeks were assessed as having either scanty colonies of keratinocytes (SCK), continuous stratified epithelium (CSE), or no observable keratinocyte growth. Eight out of the ten dermis samples (80%) in group A demonstrated CSE, and 30% of the samples in group B showed SCK. There were 10% SCK and 20% CSE in group C, and in group D, 30% SCK and 10% CSE were found. The good results in group A indicated that the fibrin glue facilitated the seeding efficiency of the keratinocytes on the dermis and that the vital factors released from the 3T3 feeder cells enhanced the growth and differentiation of the keratinocytes. This model provides an optimal system for the cultivation of keratinocytes on acellular dermis.

3T3 Cells↗