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Biomedical subjects

J C Ho

Publications and source records attributed to J C Ho.

At least 55 records · Page 3Linked to original sources
PubMed1999

Magnetic properties of Ni-Co-Cr-base Elgiloy.

The Ni-Co-Cr-base Elgiloy is one of the commonly used engineering materials. Most applications rely on its high strength, ductility, corrosion resistance and excellent fatigue life over a wide temperature range. However, in the medical application of cerebral aneurysm clips, the alloy is often subjected to strong magnetic fields associated with magnetic resonance imaging (MRI). Its paramagnetic behavior meets MRI safety requirements, but is the source of relatively large artifacts and thus less MRI-compatible for MRI procedure involving the brain. This article reports superconducting quantum interference device (SQUID) measurements on the magnetic properties of a series of Elgiloy wires in either as-drawn or heat-treated conditions. Furthermore, low-temperature calorimetry was employed to reveal the existence of submicroscopic clusters containing ferromagnetic elements such as Ni or Co in the macroscopically paramagnetic matrix.

Journal Article↗
PubMed1999

Microsatellite instability, Epstein-Barr virus, mutation of type II transforming growth factor beta receptor and BAX in gastric carcinomas in Hong Kong Chinese.

Microsatellite instability (MI), the phenotypic manifestation of mismatch repair failure, is found in a proportion of gastric carcinomas. Little is known of the links between MI and Epstein-Barr virus (EBV) status and clinicopathological elements. Examination of genes mutated through the MI mechanism could also be expected to reveal important information on the carcinogenic pathway. Seventy-nine gastric carcinomas (61 EBV negative, 18 EBV positive) from local Hong Kong Chinese population, an intermediate-incidence area, were examined. Eight microsatellite loci, inclusive of the A10 tract of type II transforming growth factor beta receptor (TbetaR-II), were used to evaluate the MI status. MI in the BAX and insulin-like growth factor II receptor (IGF-IIR) genes were also examined. High-level MI (>40% unstable loci) was detected in ten cases (12.7%) and low-level MI (1-40% unstable loci) in three (3.8%). High-level MI was detected in two EBV-associated cases (11%) and the incidence was similar for the EBV-negative cases (13%). The high-level MIs were significantly associated with intestinal-type tumours (P = 0.03) and a more prominent lymphoid infiltrate (P = 0.04). Similar associations were noted in the EBV-positive carcinomas. The high-level MIs were more commonly located in the antrum, whereas the EBV-associated carcinomas were mostly located in body. Thirteen cardia cases were negative for both high-level MI and EBV. All patients aged below 55 were MI negative (P = 0.049). Of the high-level MIs, 80% had mutation in TbetaR-II, 40% in BAX and 0% in IGF-IIR. Of low-level MIs, 33% also had TbetaR-II mutation. These mutations were absent in the MI-negative cases. Of three lymphoepithelioma-like carcinomas, two cases were EBV positive and MI negative, one case was EBV negative but with high-level MI. In conclusion, high-level MIs were present regardless of the EBV status, and were found in a particular clinicopathological subset of gastric carcinoma patient. Inactivation of important growth regulatory genes observed in these carcinomas confirms the importance of MI in carcinogenesis.

Adult↗
PubMed1999

Helicobacter pylori in Meckel's diverticulum with heterotopic gastric mucosa in a population with relatively high H. pylori prevalence rate.

BACKGROUND: Helicobacter pylori (H. pylori) colonize only foveolar gastric-type mucosa and are associated with active chronic gastritis and peptic ulcer. The aim of this study was to investigate whether H. pylori can also be found in Meckel's diverticulum which contains heterotopic gastric mucosa. METHODS: Biopsy specimens of Meckel's diverticulum resected in Queen Mary Hospital, University of Hong Kong, during the 10 year period 1986-1995 were retrieved and reviewed. Those containing gastric heterotopia were examined for the presence of H. pylori, using Warthin-Starry silver stain. RESULTS: In the 59 cases of Meckel's diverticula studied, 16 were found to contain heterotopic gastric mucosa. Helicobacter pylori were not identified in any of these cases. In one of the 16 patients a concomitant gastric biopsy was performed. Although the gastric mucosa of this patient was heavily colonized by H. pylori, again no H. pylori was found in the heterotopic gastric mucosa in the Meckel's diverticulum. CONCLUSIONS: The absence of H. pylori in all the Meckel's diverticula examined, even when the stomach was heavily colonized by the organisms, suggests that colonization of Meckel's diverticulum by H. pylori is a rare event. This, together with the overall rarity of H. pylori in all reported series of Meckel's diverticulum, argues against its causative role in complications of Meckel's diverticulum.

Adult↗
PubMed1999

Comparison of preference and ease-of-use of breath-actuated inhalation devices in children.

This study was conducted to evaluate children's and nurses' preference among the three breath-actuated devices, Turbuhaler (Astra), Autohaler (3M) and Accuhaler (Glaxo-Wellcome). This was an open study conducted in the paediatric in-patient department of Kwong Wah Hospital, Hong Kong. Subjects over 6 years of age who had not previously used any inhalation devices were recruited. The three devices were in random order. The preferences of subjects and nurses were ranked in a three-point scale. The children had a statistically significant preference for Accuhaler, while the nurses preferred to teach both Accuhaler and Autohaler but not the Turbuhaler.

Child↗
PubMed1999

Acute fish liver intoxication: report of three cases.

The livers of some larger fish such as shark, tuna and seabass have been reported to be responsible for a peculiar poisoning causing headaches and desquamation. This type of poisoning can also be induced by ingestion of the livers of the sea whale, the polar bear and the seal. Since these animals contain an extremely large quantity of vitamin A in their livers and the symptoms of poisoning in the patients resembled those of patients with acute hypervitaminosis A, the poisoning was believed to have been caused by excessive vitamin A intake. We observed an episode of acute fish liver intoxication in which 3 man experienced dizziness, headache, blurred vision, nausea, vomiting, fever, and desquamation after ingesting the liver of the grouper fish Cephalopholis boenak (C. boenak). One of the patients had full-blown symptoms and presented with a high fever, headache, dizziness, generalized aching pain, and superficial vesicles and bullae of the skin. The treatment was mainly supportive. In the follow-up period, he subsequently developed hair loss and diffuse peeling of the skin on his palms and soles. Acute fish liver intoxication is rare, especially in subtropical regions. Symptomatologically, the clinical pictures of these patients were comparable to acute hypervitaminosis A or retinoid intoxication. The average vitamin A content in the grouper (C. boenak) is high enough to cause acute vitamin A intoxication. Moreover, ethanol may play a potentiating role in this type of event.

Acute Disease↗
PubMed1999

Use of infrared emission detection thermometer in Chinese neonates.

OBJECTIVE: To evaluate the reproducibility of Thermoscan, an infrared emission detection ear thermometer, and to establish the normal reference range of ear temperature in Chinese neonates. METHODS: Neonates were recruited from the inpatients population with exclusion of those suffering from infections. RESULTS: Forty-nine neonates were recruited with 1,115 temperature taking sessions. Mean left ear temperature was 36.64 degrees C +/- 0.35 degree C. Mean right ear temperature was 36.64 degrees C +/- 0.37 degree C. Clinical repeatability for left and right ear was 0.17 degree C and 0.17 degree C, respectively. CONCLUSION: Thermoscan produced reproducible results in Chinese neonates. The normal range of ear temperature for Chinese neonates is 35 degrees C to 37 degrees C. Ear temperature > 37.8 degrees C should be regarded as fever.

Asian People↗
PubMed1998

A high affinity, mu-opioid receptor-selective enkephalin analogue lacking an N-terminal tyrosine.

We report a high affinity, mu opioid receptor selective enkephalin analogue in which the N-terminal tyrosine residue thought to be required for such high affinity is replaced by phenylalanine. The high affinity can be traced to a shift of the ligand's N-terminal residue within the mu receptor binding pocket, which diminishes the importance of the usual hydrogen bond between the tyrosine phenolic moiety and the receptor.

Enkephalins↗
PubMed1998

Defective IL-2 receptor expression in lymphocytes of patients with arsenic-induced Bowen's disease.

The immune function of peripheral mononuclear cells (MNC) in patients with endemic arsenic-induced Bowen's disease (BD) was investigated. Many cytokines and immune-related factors were determined in the present study. Interleukin-1beta and TNF-alpha production was used as an indicator of monocyte/macrophage function. II-2 and sIL-2R production was used as an indicator of lymphocyte activation. The release of sCD4 and sCD8 was used as an indicator of activation of respective T-cell subpopulations. Production of IFN-gamma and IL-2 reflected the cellular effector function of helper T-cells type 1. In vivo cell-mediated immunity was also assessed by estimation of the percentage of T-cells in peripheral blood MNC and the nonspecific delayed-type hypersensitivity (DTH) response to 2,4-dinitrochlorobenzene (DNCB). Both assays revealed depressed cell-mediated immunity in BD. Compared with healthy controls, spontaneous and PHA-induced IFN-gamma and TNF-alpha production was significantly decreased in BD whereas spontaneous release of IL-2, sCD4 and sCD8 was significantly increased. Although PHA stimulation increased IL-2 release, the expression of IL-2R alpha and beta chains and the release of sIL-2R were not proportionately increased in BD. In addition, IL-2-mediated [3H]-thymidine incorporation by MNC in patients with BD was significantly decreased. These findings suggest that the defective cell-mediated immune function in BD is due to impairment of membrane IL-2R expression in lymphocytes after stimulation.

Aged↗
PubMed1998

Birthplace and yield of nipple aspirate fluid in Chinese women.

The different rates of breast cancer found between Chinese women in Asia compared with Chinese-born women in the United States suggest that dietary and environmental factors may be of etiological significance. We evaluated the proportion of 480 premenopausal Chinese women who yielded nipple aspirate fluid (NAF) by birthplace in Asia versus the United States and by reproductive and other risk factors. Birthplace was used as a surrogate for presumed differences in exposures during gestation, childhood, and adolescence that might influence yield of NAF in premenopausal women. In United States-born Chinese women compared with Asia-born Chinese women, the proportion yielding NAF was 44 of 95 (46.3%) versus 120 of 385 (31.2%), respectively. The relative risk of yield of NAF in United States-born women compared with Asia-born women was odds ratio = 2.37 (95% confidence interval, 1.26-4.47). Independent positive associations of NAF yield were also found with history of parity and breast feeding, cerumen phenotype, and a negative association with ever use of oral contraceptives. These findings support the hypothesis that early environmental exposures may have long-lasting physiological effects discernible in the breast glands of adult women.

Adult↗
PubMed1997

Colorectal carcinoma in Hong Kong: epidemiology and genetic mutations.

The incidence of colorectal carcinoma is rising at an alarming pace in Asian urban societies such as Hong Kong. Detailed examination of the epidemiological pattern and genetic mutation of colorectal cancer in the Hong Kong Chinese population is overdue. We compared the reported age incidence of colorectal carcinoma in Hong Kong with that of Scotland and other countries. Hong Kong showed a much higher incidence of colorectal carcinoma among the young age groups. By comparison with other countries, this raised incidence among the young appeared to be related to southern Chinese societies. The recent dramatic rise in colorectal cancer in Hong Kong was largely attributable to an increase in the over 50 years age group, while the young incidence remained unchanged. We also defined the mutation spectrum of p53 and Ki-ras in 67 unselected cases by direct DNA sequencing. Interestingly, insertion/deletion mutations in p53 from colorectal carcinoma in Hong Kong showed a significantly higher frequency (17.2%) than the Scottish data (0%) and the world database (6.6%), although the overall frequency of p53 mutation (43%) in Hong Kong was similar to others. The high incidence of colorectal carcinoma in young people and the raised proportion of frameshift mutations in p53 encourage further search for a genetic basis for susceptibility to this disease in the Hong Kong Chinese population.

Adolescent↗
PubMed1997

Paediatric upper gastrointestinal endoscopy: a 2-year review.

OBJECTIVE: To review the paediatric upper gastrointestinal endoscopy service in a paediatric department in Hong Kong. METHODS: Records of all endoscopies undertaken in this department from May 1995 to January 1996 were retrieved and analysed. RESULTS: The commonest indication for upper endoscopy was dyspepsia with 88% positive histological findings. Helicobacter pylori (H. pylori) was found in 25% of this group of children. CONCLUSION: Paediatric upper gastrointestinal endoscopy service is invaluable in a paediatric department by providing useful diagnostic information which would otherwise be missed.

Child↗
PubMed1996

Titanium aneurysm clips: Part I--Mechanical, radiological, and biocompatibility testing.

Most aneurysm clips are made of cobalt-based alloys. Although these clips are nonferromagnetic, they still produce artifact that degrades the quality of magnetic resonance (MR) images. A new aneurysm clip of pure titanium was developed to minimize artifact on postoperative MR images. We evaluated these clips in a series of mechanical tests in vitro, biocompatibility tests in rabbits, and radiological tests in greyhound dogs. The clip sizes and shapes matched those of conventional aneurysm clips. The average closing forces ranged between 151.6 and 181.8 g and were not diminished by repeated sterilization or stress. After > 20 million cycles of high-pressure and high-frequency pulsations, the clips did not open and the closing forces were not reduced. Titanium aneurysm clips implanted in the subarachnoid space of 12 rabbits for 1 or 6 months produced mild gliosis identical to that produced by implantation of cobalt alloy clips in 12 control rabbits. Based on pre- and postoperative weights and electron microscopic scans, the titanium implants did not corrode. The artifact on computed tomographic and MR imaging produced by a titanium clip placed on the internal carotid artery of a greyhound was less than that produced by an identical cobalt-chrome alloy clip by a factor of two to three. This study demonstrated that titanium aneurysm clips are mechanically equivalent to conventional clips, biocompatible, and corrosion resistant. Furthermore, titanium clips have superior imaging characteristics, creating less computed tomographic and MR imaging artifact and permitting better resolution of anatomic structures than cobalt alloy clips.

Animals↗
PubMed1996

Thymine dimer-dependent incision on ultraviolet light damaged-DNA in cell-free extracts of Chlorella pyrenoidosa.

Cell-free extracts of the unicellular algae Chlorella pyrenoidosa induce a UV-dependent incision of both phi x 174 RFI DNA and a 27-mer double-stranded oligonucleotide containing a single thymine dimer, as analyzed by agarose and denaturing polyacrylamide gel electrophoresis, respectively. The incision reaction occurred only on the thymine dimer-containing strand of the 27-mer, and a major incision product of 17-mer was observed. Addition of ATP or ATP-regenerating system to algal extracts increased the effect of DNA incision.

Base Sequence↗
PubMed1995

The effect of nicotine and its interaction with carbon tetrachloride in the rat liver.

In order to study the effects of nicotine on liver, groups of rats were given nicotine doses that simulated those seen in chronic smoking (54 and 108 mumol/l of nicotine) for 10 days. A subgroup was also given a single subcutaneous injection of 6 g/kg of carbon tetrachloride (CCl4) shortly before the animals of the group were killed. Histology demonstrated a significant hepatotoxic effect in the group receiving 108 mumol/l of nicotine when compared with the control group in the form of fatty change, focal or confluent necrosis and dark-cell change. The effects in pregnant rats were less severe. Carbon tetrachloride alone induced significant fatty change and focal necrosis in non-pregnant rats but not in pregnant rats. Nicotine also aggravated the CCl4 induced pathological changes in livers of both non-pregnant and pregnant animals. Thus nicotine alone, when given at a concentration of 108 mumol/l, exerted hepatotoxic effects; the alkaloid also aggravated the hepatotoxicity of CCl4. Pregnant rats were more resistant to the hepatotoxic effects produced by nicotine and CCl4.

Animals↗
PubMed1994

Flow cytometric analysis of DNA ploidy in hepatocellular carcinoma.

To examine the prognostic and pathobiologic significance of DNA content, the authors studied the surgically resected hepatocellular carcinomas of 69 patients by flow cytometric analysis. Homogeneity of DNA content within individual tumor nodules was present in 15 (88%) of 17 specimens examined. Similarly, homogeneity of DNA content in tumors having multiple nodules was found in 8 (73%) of 11 specimens. In 64 tumors with homogeneous DNA content evaluated further, DNA aneuploidy was present in 30 (46.9%) specimens, and the proportion of aneuploid tumors was similar in the large (> 5 cm in diameter, n = 35) and small (< or = 5 cm, n = 25) lesions, at 42.9% and 40%, respectively. Overall, the diploid tumors had serum alpha-fetoprotein levels increased to greater than 500 micrograms/mL more frequently than did the aneuploid tumors (P = .037). DNA content did not correlate significantly with hepatitis B surface antigen, presence of liver cirrhosis, cellular differentiation, tumor size, or tumor encapsulation. DNA content also did not influence tumor invasiveness in terms of liver invasion, presence of tumor microsatellites, or venous permeation. With multivariate Cox regression analysis, tumor encapsulation (P = .015), negative resection margin (P = .007), and DNA ploidy pattern stratified according to large and small tumors (P = .024) were favorable prognostic factors. In the small tumors, a diploid DNA pattern was associated with significantly better patient survival than was an aneuploid pattern (P = .012). In the large tumors, on the contrary, a diploid pattern was associated with poorer patient survival than was an aneuploid pattern (P = .029). The authors conclude that DNA ploidy pattern in hepatocellular carcinomas is homogeneous and stable. It supplements other predictors in prognostication when the lesions are stratified into small and large ones by tumor size. It is of particular importance as a predictor because it can be assessed preoperatively in needle-biopsy specimens.

Adult↗
PubMed1991

[Pilomatricoma-a clinicopathological analysis of 22 cases, including 2 cases of bullous pilomatricoma].

Twenty-two patients with pilomatricoma seen from January 1986 to October 1990 were analyzed retrospectively. The incidence of pilomatricoma in our dermatopathologic material is 1 in every 50 cases of skin tumors. Male to female ratio is 1:2. Half of the tumors appeared before the age of 30. Most of the tumors develop in the head, neck and upper extremities. Two pilomatricomas appeared with overlying bullae. Pathologically, multiple dilated lymphatics in the dermis were found above the typical nests of shadow cells and basophilic cells. Clues to clinical diagnosis are summarized below. The stony hard, deep-seated tumor, covered by normal skin, is usually located in the upper extremity. Tumors with blue-red discoloration, firm or elastic, frequently found in eyelid and face, are located more superficially, clinically they should be differentiated from epidermal cysts. Erythematous protruding tumors occur in the scalp or face. Bullous pilomatricoma is characteristically manifested as a flaccid, thick-walled bulla with an underlying palpable hard nodule, usually seen in the shoulder, upper arm or the head.

Adolescent↗