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Biomedical subjects

Y M Chan

Publications and source records attributed to Y M Chan.

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

Gastric adenocarcinoma presenting with persistent, mild gastrointestinal symptoms in pregnancy. A case report.

BACKGROUND: Mild gastrointestinal symptoms are common during pregnancy but can also be the only symptoms in stomach cancer until the late stage. Clinicians' reluctance to pursue diagnostic studies appears to be a major contributing factor to delayed diagnosis and poor outcome. We report a case of maternal death to alert clinicians to this rare possibility. CASE: A 36-year-old woman had persistent, mild epigastric discomfort, nausea, vomiting and frequent episodes of dark stools since the second trimester of pregnancy. These were attributed to peptic ulcer and an iron supplement given, without investigation. Gastroscopy was performed only at 32 weeks of gestation, when the patient had heavy hematemesis. Biopsy confirmed the diagnosis of poorly differentiated adenocarcinoma of the stomach. Cesarean section was performed after steroid therapy. Advanced stomach cancer with stomach perforation was found. Curative surgery was not possible. The patient died four weeks after delivery. CONCLUSION: Stomach cancer is a rare complication of pregnancy. Delay in diagnosis is commonly due to clinicians' reluctance to request diagnostic studies and the nonspecific symptoms of the disease. Early recognition and diagnosis are the only possibilities for a better outcome. Clinicians must be alert to this possibility and include this in the differential diagnosis of minor gastrointestinal discomfort during pregnancy.

Adenocarcinoma↗
PubMed1998

Molecular organization of sarcoglycan complex in mouse myotubes in culture.

The sarcoglycans are a complex of four transmembrane proteins (alpha, beta, gamma, and delta) which are primarily expressed in skeletal muscle and are closely associated with dystrophin and the dystroglycans in the muscle membrane. Mutations in the sarcoglycans are responsible for four autosomal recessive forms of muscular dystrophy. The function and the organization of the sarcoglycan complex are unknown. We have used coimmunoprecipitation and in vivo cross-linking techniques to analyze the sarcoglycan complex in cultured mouse myotubes. We demonstrate that the interaction between beta- and delta-sarcoglycan is resistant to high concentrations of SDS and alpha-sarcoglycan is less tightly associated with other members of the complex. Cross-linking experiments show that beta-, gamma-, and delta-sarcoglycan are in close proximity to one another and that delta-sarcoglycan can be cross-linked to the dystroglycan complex. In addition, three of the sarcoglycans (beta, gamma, and delta) are shown to form intramolecular disulfide bonds. These studies further our knowledge of the structure of the sarcoglycan complex. Our proposed model of their interactions helps to explain some of the emerging data on the consequences of mutations in the individual sarcoglycans, their effect on the complex, and potentially the clinical course of muscular dystrophies.

Amino Acid Sequence↗
PubMed1998

The Drosophila LIM-only gene, dLMO, is mutated in Beadex alleles and might represent an evolutionarily conserved function in appendage development.

The process of wing patterning involves precise molecular mechanisms to establish an organizing center at the dorsal-ventral boundary, which functions to direct the development of the Drosophila wing. We report that misexpression of dLMO, a Drosophila LIM-only protein, in specific patterns in the developing wing imaginal disc, disrupts the dorsal-ventral (D-V) boundary and causes errors in wing patterning. When dLMO is misexpressed along the anterior-posterior boundary, extra wing outgrowth occurs, similar to the phenotype seen when mutant clones lacking Apterous, a LIM homeodomain protein known to be essential for normal D-V patterning of the wing, are made in the wing disc. When dLMO is misexpressed along the D-V boundary in third instar larvae, loss of the wing margin is observed. This phenotype is very similar to the phenotype of Beadex, a long-studied dominant mutation that we show disrupts the dLMO transcript in the 3' untranslated region. dLMO normally is expressed in the wing pouch of the third instar wing imaginal disc during patterning. A mammalian homolog of dLMO is expressed in the developing limb bud of the mouse. This indicates that LMO proteins might function in an evolutionarily conserved mechanism involved in patterning the appendages.

Alleles↗
PubMed1998

Miranda as a multidomain adapter linking apically localized Inscuteable and basally localized Staufen and Prospero during asymmetric cell division in Drosophila.

Neuroblasts in the developing Drosophila CNS asymmetrically localize the cell fate determinants Numb and Prospero as well as prospero RNA to the basal cortex during mitosis. The localization of Prospero requires the function of inscuteable and miranda, whereas prospero RNA localization requires inscuteable and staufen function. We demonstrate that Miranda contains multiple functional domains: an amino-terminal asymmetric localization domain, which interacts with Inscuteable, a central Numb interaction domain, and a more carboxy-terminal Prospero interaction domain. We also show that Miranda and Staufen have similar subcellular localization patterns and interact in vitro. Furthermore, miranda function is required for the asymmetric localization of Staufen. Miranda localization is disrupted by the microfilament disrupting agent latrunculin A. Our results suggest that Miranda directs the basal cortical localization of multiple molecules, including Staufen and prospero RNA, in mitotic neuroblasts in an actin-dependent manner.

Actins↗
PubMed1998

Eclampsia-an 11-year experience.

A retrospective study of all deliveries from 1983 to 1993 at the Tsan Yuk Hospital to evaluate the incidence was performed and outcome of eclampsia. Eclampsia occurred in 12 patients. The incidence was approximately 2 per 10,000 deliveries and was relatively constant during the study period. Most convulsions occurred during the intrapartum (41.7%) and post-partum (50.0%) periods, and about half of them had no warning signs. There were no maternal or perinatal deaths. Prophylactic anticonvulsants should be given to all patients with warning signs; however, eclampsia is not always preventable.

Journal Article↗
PubMed1997

The Chinese in Britain.

"This research note offers a brief historical perspective on the relationship between Hong Kong and Britain and describes the demographic profile of the Chinese community in Britain...[using] information obtained from the 1991 [UK] Census.... The data analysis shows that the Chinese population is widely dispersed and increasing rapidly, and is characterised by a high child-bearing capacity and a low rate of unemployment."

Acculturation↗
PubMed1997

Oral misoprostol for cervical priming in non-pregnant women.

Endometrial biopsy and hysteroscopy are important investigations in women presenting with abnormal vaginal bleeding. Endometrial biopsy is often performed as an outpatient procedure by endometrial aspiration. Difficulty in entering the internal cervical os may be encountered, especially in nulliparous women. The same problem may occur during hysteroscopy or dilatation and curettage. It is well known that use of a cervical priming agent is effective in reducing complications during cervical dilatation in pregnant women. However, its use in non-pregnant women is not well established. We compared oral misoprostol versus placebo for a cervical priming effect in non-pregnant women prior to hysteroscopy. The cumulative force required for cervical dilatation was significantly lower whereas the baseline cervical dilatation was significantly greater in the misoprostol group. We conclude that oral misoprostol is effective for pre-operative cervical dilatation in non-pregnant women.

Abortifacient Agents, Nonsteroidal↗
PubMed1997

Attitudes of Hong Kong nurses toward cadaveric organ donation.

OBJECTIVES: The objectives of this descriptive correlational study were to (a) examine Hong Kong nurses' attitudes toward cadaveric organ donation, and (b) determine if there were any relationships among the nurses' attitudes and their behaviors, or knowledge regarding cadaveric organ donation, or their experience in caring for cadaveric organ donors/recipients, in order to identify any obstacles in promoting organ donation in Hong Kong. DESIGN: The Bidigare and Oermann (1991) Questionnaire and Chiu et al. (1991) Questionnaire were modified to a five-section questionnaire used in the study. SAMPLE/SETTING: The sample consisted of 60 registered nurses from the intensive care unit (ICU), operation room (OR), or renal and surgical units in one of the public hospitals under the Hong Kong Hospital Authority. METHODS: Questionnaires were given to the selected participants through their wards. The registered nurses returned completed questionnaires to their wards which were collected by the researchers. RESULTS: Most of the nurses (84.6%) supported the concept of cadaveric donation but only 23.5% had signed the donor card. It also revealed that nurses attitudes and behaviors regarding cadaveric organ donation were positively correlated to their knowledge and experience of caring for organ donors and recipients and there was knowledge deficit among the nurses concerning cadaveric organ donation. CONCLUSION: While nurses with knowledge and previous experience in caring for cadaveric organ donors and recipients had a more positive attitude toward cadaveric organ donation, there is a knowledge deficit among the nurses. An educational program about organ donation is suggested to change their attitudes and hence increase organ procurement.

Adult↗
PubMed1996

Genetic analysis of a severe case of Dowling-Meara epidermolysis bullosa simplex.

The epidermis serves an important protective function, which it manifests by producing an extensive cytoskeletal architecture, the unique feature of which are keratin filaments. Through studies that began with epidermolysis bullosa simplex (EBS) and now extend to a group of autosomal dominant human blistering skin disorders it was discovered that defects in the keratin genes lead to cell fragility and degeneration upon mechanical trauma. In most cases of EBS, point mutations occur in the keratin 5 (K5) and K14 genes expressed in the basal layer of the epidermis. The precise location of the mutation and the degree to which it causes perturbations in filament assembly correlate with disease severity. In the present study, we examine a case of EBS, which clinically lies at the severe end of the spectrum of Dowling-Meara EBS and which shows keratin filament clumping in suprabasal as well as basal cells. We show that one of the two K14 alleles has a single point substitution, giving rise to a Y129D mutation. This mutation resides 4 residues internal to the R125C/H hotspot known to account for the majority of Dowling-Meara cases. We provide functional and structural evidence to suggest why the Y129D mutation may be capable of creating such a severe form of EBS.

Adult↗
PubMed1996

Concanavalin A-induced apoptosis in murine macrophages through a Ca(2+)- independent pathway.

Concanavalin A (ConA), normally a mitogen of T lymphocytes, was found to induce apoptosis or programmed cell death in murine peritoneal macrophages. The following observations support this assertion: 1) incubation of peritoneal macrophages or cultured PU5-1.8 macrophage cells with ConA caused a dose- and time-dependent reduction of mitochondrial dehy-drogenase activity as measured by 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, 2) treatment of cells with ConA induced formation of apoptotic bodies as seen under the confocal laser scanning microscope, 3) challenge of cells with ConA produced a considerable amount of cell debris with DNA content next to G0 phase as revealed by flow cytometry and 4) ConA was able to elicit DNA fragmentation in these cells. The involvement of Ca(2+) in mediating the apoptosis was studied in single cells by confocal laser scanning microscope using the Ca(2+) fluorescence dye, fluo-3. Our results show that ConA induced an immediate rise of intracellular free Ca(2+) concentration as well as opening of Ca(2+) channels on cell surface. But when the cells were treated with 1,2-bis(o-aminophenoxy) ethane-N, N, N', N'-tetraacetic acid/AM (BAPTA/AM), a Ca(2+) chelator, to buffer the rise of internal Ca(2+), ConA still caused DNA fragmentation. Furthermore, injection of Ca(2+) into the cell with ionomycin had no stimulatory effect on DNA fragmentation. These results suggest that Ca(2+) changes induced by ConA are not a prerequisite for apoptosis in macrophages.

Journal Article↗
PubMed1995

Fertilization and pregnancy achieved by intracytoplasmic injection of sperm retrieved from testicular biopsies.

OBJECTIVE: To determine if intracytoplasmic sperm injection using testicular sperm is effective in the treatment of infertile couples with obstructive azoospermia. DESIGN: Case report. SETTING: Tertiary care teaching medical center. METHODS: Intracytoplasmic sperm injection was performed in two patients using testicular sperm after microsurgical epididymal sperm aspiration failed. RESULTS: In both cases fertilization and embryos resulted. One patient conceived and delivered triplets. There was no evidence of chromosomal abnormality or congenital malformation. CONCLUSIONS: Intracytoplasmic sperm injection using sperm extracted from testicular biopsy appears to be effective in the treatment of infertile couples with obstructive azoospermia when microsurgical sperm aspiration fails.

Adult↗
PubMed1995

Syphilitic labyrinthitis--an update.

Forty-eight patients with syphilitic labyrinthitis have been treated and followed up for periods of six months to 25 years; interpretation of the hearing results must be in the light of the natural history of this condition which is perceived to be progression of hearing loss to profound deafness. At the beginning of the series treatment was with ampicillin alone and on this treatment 11 ears with useful hearing were maintained at this level. The group with combined ampicillin and prednisone treatment, which included some failures from ampicillin alone, maintained useful hearing in 28 out of 29 ears. Those treated initially with ampicillin and prednisone and later also given regular injections of ACTH, maintained hearing in 16 out of 17 ears. At the outset, there were 29 profoundly deaf ears. One of these recovered some useful hearing but two ears with useful hearing at the outset became profoundly deaf so that at the end there were 30 profoundly deaf ears. However, all patients as opposed to ears, with useful hearing at the outset were left with some hearing; no patient became profoundly deaf.

Adrenocorticotropic Hormone↗
PubMed1995

Pregnancy following renal transplantation: the experience in Hong Kong.

OBJECTIVE: To assess the outcome of pregnancies occurring after renal transplantation, and to review the factors conductive to a favourable outcome. METHOD: A retrospective review of 8 pregnancies occurring after renal transplantation from 1988 to 1992 in a tertiary referral centre in Hong Kong. RESULT: A very high successful pregnancy rate was achieved with minimal maternal and perinatal morbidity in the cases reviewed. CONCLUSION: Good prepregnancy counselling and stringent criteria for pregnancy assessment appears to be crucial factors for a favourable pregnancy outcome.

Adult↗
PubMed1995

Peri-operative administration of rectal diclofenac sodium. The effect on renal function in patients undergoing minor orthopaedic surgery.

In a randomized, double-blind study, we administered placebo and diclofenac sodium 100 mg suppositories 1 h pre-operatively and on the first post-operative morning to 22 adult patients undergoing minor orthopaedic surgery. A standardized post-operative intravenous fluid regimen was instituted until oral fluids were tolerated. Renal function was assessed pre-operatively, and on the first and second post-operative days by the measurement of urine output, creatinine, urea, sodium, potassium and NAG (N-acetyl-b-D-glucosaminidase) levels and serum creatinine, urea, sodium and potassium concentrations. On the first post-operative day, the diclofenac group demonstrated a reduced urinary sodium excretion. On the second post-operative day, a reduced urinary NAG/creatinine ratio was observed in the diclofenac group when compared to placebo. We conclude that peri-operative administration of diclofenac causes changes in renal function consistent with prostaglandin inhibition on the first post-operative day but had no lasting adverse effects in this group of patients. Our results reinforce the need for caution when administering this drug in the context of pre-existing renal impairment.

Acetylglucosaminidase↗
PubMed1994

Genetic and clinical mosaicism in a type of epidermal nevus.

BACKGROUND: Many skin disorders are characterized by a mosaic pattern, often with alternating stripes of affected and unaffected skin that follow the lines of Blaschko. These nonrandom patterns may be caused by a postzygotic mutation during embryogenesis. We studied the genetic basis of one such disorder, epidermal nevus of the epidermolytic hyperkeratotic type. Epidermolytic hyperkeratosis is an autosomal dominant blistering skin disease arising from mutations in the genes for keratin (K) 1 and 10. The offspring of patients with epidermal nevi may have generalized epidermolytic hyperkeratosis. METHODS: We studied the K1 and K10 genes in blood and in the keratinocytes and fibroblasts of lesional and nonlesional skin from three patients with epidermal nevi and four of their offspring with epidermolytic hyperkeratosis. RESULTS: In the patients with epidermal nevi, point mutations in 50 percent of the K10 alleles of epidermal cells were found in keratinocytes from lesional skin; no mutations were detected in normal skin. This mutation was absent or underrepresented in blood and skin fibroblasts. In the offspring with epidermolytic hyperkeratosis, the same mutations as those in the parents were found in 50 percent of the K10 alleles from all cell types examined. CONCLUSIONS: Epidermal nevus of the epidermolytic hyperkeratotic type is a mosaic genetic disorder of suprabasal keratin. The correlation of mutations in the K10 gene with lesional skin and the correlation of the normal gene with normal skin provide evidence that genetic mosaicism can cause clinical mosaicism.

Alleles↗