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Biomedical subjects

L M Wong

Publications and source records attributed to L M Wong.

At least 19 recordsLinked to original sources
PubMed2006

Allele frequencies and haplotypes of 12 Y-STR loci for the local Chinese population in Hong Kong.

Haplotype frequencies were established for 12 Y-chromosome STR loci, including all loci recommended by Scientific Working Group on DNA Analysis Methods Y-STR Subcommittee (DYS391, DYS389I/II, DYS439, DYS393, DYS390, DYS385a/b, DYS438, DYS19 and DYS392) plus DYS437, in the local Chinese population in Hong Kong. In a sample of 481 unrelated males, it was possible to define 424 different haplotypes of which 388 were unique, 26 was found in two individuals, 2 were shared in three individuals, 5 were shared in four individuals and 3 were shared in five individuals. The allele diversity values for each locus ranged from 0.4273 (DYS438) to 0.9555 (DYS385a/b). The observed haplotype diversity value and discrimination capacity were 0.9992 and 0.8815, respectively. In a genetic study of these unrelated males, triple alleles were found at the DYS358 locus in six individuals. The combined Y-chromosome STR polymorphisms provide a powerful discrimination tool for routine forensic applications.

Chromosomes, Human, Y↗
PubMed2003

Changes in heart rate and R-wave amplitude with posture.

BACKGROUND: Effect of gravity on heart rate and blood pressure are well documented but the effect of posture on R-wave amplitude has not been studied. AIM: To investigate the effect of posture on the heart rate (HR) and R-wave amplitude (RWA). METHODS: The electrocardiograph (ECG) was recorded in 20 young subjects on two occasions. A 5 minute recording of resting ECG was taken with the subject adopting the following postural cycle: lying, sitting, standing, sitting and lying positions. RESULTS: The standing HR was significantly higher than that in sitting and lying positions, but the RWA was significantly lower in standing compared to the sitting and lying postures. The HR significantly increased at the initial phase of postural changes, irrespective of the position. For example, the HR increased from lying to sitting (66.6+/-2.3 to 85.0+/-10.9 beat x min(-1)) but also increased when changed from sitting to lying (70.6+/-10.6 to 85.2+/-8.7 beat x min(-1)). CONCLUSION: Body posture has an effect on HR and RWA. The changes are probably related to orthostatic haemodynamic stress as well as changes in cardiac electrical axis. Whether the cause of the initial increase in the HR during postural change was attributed to skeletal muscle reflex or venous return requires further investigation.

Adult↗
PubMed2001

Surgical infections in patients with chronic renal failure.

Patients with chronic renal failure and uremia have impaired host defenses and wound healing that can lead to an increased risk of infection in addition to a frequent need for surgical procedures with synthetic grafts and catheters. Antibiotic therapy plus timely surgical intervention in removal of infected grafts and catheters is crucial for infection control and patient survival. Other surgical infections, such as wound problems, intraabdominal infections, fungal infections, diabetic foot ulcers, and necrotizing soft tissue infections must be attended to promptly.

Antibiotic Prophylaxis↗
PubMed2000

Two novel myogenic factors identified and isolated by sequential isoelectric focusing and sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

A number of environmental factors were used experimentally to enhance myogenesis during muscle regeneration; however, many hormones and growth factors have been shown to have the ability to increase the rate of satellite cell division, but they only work on satellite cells that are already active in many animal experiments. Recently, the crushed muscle extract (CME) of rats was found to be able to trigger dormant adult rat satellite cells to re-enter the cell mytogenic cycle; however, the identity of the active factors present in rat CME remains unknown. In the present study, the CME was fractionated by the strategy of sequential isoelectric focusing and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) coupled with functional analysis by myoblast culture. Two satellite cell-specific myogenic factors were identified and purified from CME by this strategy. One of the factors has a molecular mass of around 7 kDa and another about 39 kDa. The factor of 39 kDa could be retained in heparin-Sepharose column and eluted with phosphate-buffered saline (PBS) containing 1 M NaCl, but the 7 kDa factor did not bind to the heparin column. These two purified myogenic factors could synergistically trigger the proliferation and differentiation of dormant satellite cells, whose progenies subsequently fuse in vitro, or fuse to pre-existing partially damaged muscle fibers to form full repair of the damaged muscle fibers or to form new myotubes to replace the completely damaged muscle fibers during the cascade of muscle healing and regeneration in vivo. The identities of these two myogenic factors are under study.

Animals↗
PubMed2000

Improved survival with screening for hepatocellular carcinoma.

Hepatocellular cancer (HCC) is a frequent cause of cancer death worldwide. Although successful screening programs exist in Asian countries, the role for screening in the United States is not clear. The purpose of this study is to determine if screening has an effect on survival in a predominantly Asian population in Hawaii. We retrospectively reviewed cases of HCC from 1993 to 1998 for demographic data, risk factors, symptoms, stage, treatment, and survival. Patients were divided into 3 groups according to presentation: symptomatic (S), asymptomatic (A), and asymptomatic but screened for disease (A/Sc). Kaplan-Meier analysis was performed on overall survival by group. Ninety-one patients were referred for HCC. There were 56 patients in group S, 19 patients in group A, and 16 patients in group A/Sc. Patients in group A/Sc survived significantly longer than those in group S (P =.009), with the former group having a median survival of 1,399 versus 234 days for group S. Median survival for group A was 545 days and did not differ significantly from the other groups. Patients who are asymptomatic and screened for HCC have an increased survival compared with those patients who present with symptoms. This may justify the use of a formal screening program for HCC in Hawaii, but we would need to investigate this prospectively.

Adult↗
PubMed2000

Epidemiology of diabetes mellitus in children in Hong Kong: the Hong Kong childhood diabetes register.

OBJECTIVES: To establish a registry for Chinese children with onset of type 1 (insulin dependent) diabetes mellitus before 15 years of age and to determine the incidence of childhood onset type 1 diabetes mellitus in Chinese children in Hong Kong. RESEARCH DESIGN AND METHODS: A registry was established in 1997 to collect childhood diabetes cases retrospectively from all districts in Hong Kong. The study included all newly diagnosed cases of diabetes with onset < 15 yr of age from 1st January 1984 to 31 December 1996. Primary ascertainment was based on review of medical records at all regional public hospitals in Hong Kong and survey of all the registered practitioners in Hong Kong. The secondary source of validation was made impractical, if not impossible, because of the recent implementation of the Personal Data Privacy Ordinance in Hong Kong. RESULTS: A total of 255 diabetic cases were identified, 227 type 1 diabetes mellitus (218 were Chinese), 18 type 2 diabetes mellitus and 11 secondary diabetes. 246 patients were Chinese and 9 non-Chinese. The age-standardized incidence of type 1 and type 2 diabetes mellitus in southern Chinese children in Hong Kong was 1.4/100,000/yr and 0.1/100,000/yr respectively for children < 15 yr of age during the study period. The incidence rates for type 1 diabetes were 0.9, 1.5 and 1.7 per 100,000/yr for 0-4 years, 5 to 9 years and 10 to 14 years age-groups respectively. The incidence for males was 1.2/100,000/yr and for females 1.7/100,000/yr. A significant increase in the incidence was demonstrated during the study period by simple linear regression (slope 0.14/100,000/year, r2 = 0.73, p = 0.0002) CONCLUSIONS: A diabetic registry is established in Hong Kong. This study documents a very low incidence rate of childhood type 1 diabetes mellitus in southern Chinese children in Hong Kong and we have seen an increasing incidence of the disease in the past 13 years.

Adolescent↗
PubMed1999

Differential cytokine modulation and T cell activation by two distinct classes of thalidomide analogues that are potent inhibitors of TNF-alpha.

TNF-alpha mediates both protective and detrimental manifestations of the host immune response. Our previous work has shown thalidomide to be a relatively selective inhibitor of TNF-alpha production in vivo and in vitro. Additionally, we have recently reported that thalidomide exerts a costimulatory effect on T cell responses. To develop thalidomide analogues with increased anti-TNF-alpha activity and reduced or absent toxicities, novel TNF-alpha inhibitors were designed and synthesized. When a selected group of these compounds was examined for their immunomodulatory activities, different patterns of cytokine modulation were revealed. The tested compounds segregated into two distinct classes: one class of compounds, shown to be potent phosphodiesterase 4 inhibitors, inhibited TNF-alpha production, increased IL-10 production by LPS-induced PBMC, and had little effect on T cell activation; the other class of compounds, similar to thalidomide, were not phosphodiesterase 4 inhibitors and markedly stimulated T cell proliferation and IL-2 and IFN-gamma production. These compounds inhibited TNF-alpha, IL-1beta, and IL-6 and greatly increased IL-10 production by LPS-induced PBMC. Similar to thalidomide, the effect of these agents on IL-12 production was dichotomous; IL-12 was inhibited when PBMC were stimulated with LPS but increased when cells were stimulated by cross-linking the TCR. The latter effect was associated with increased T cell CD40 ligand expression. The distinct immunomodulatory activities of these classes of thalidomide analogues may potentially allow them to be used in the clinic for the treatment of different immunopathological disorders.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1999

Amino-substituted thalidomide analogs: potent inhibitors of TNF-alpha production.

Thalidomide, (1), is a known inhibitor of TNF-alpha release in LPS stimulated human PBMC. Herein we describe the TNF-alpha inhibitory activity of amino substituted analogs of thalidomide (1) and its isoindolin-1-one analog, EM-12 (2). The 4-amino substituted analogs were found to be potent inhibitors of TNF-alpha release in LPS stimulated human PBMC.

Blood↗
PubMed1998

Thalidomide analogs and PDE4 inhibition.

N-Phthaloyl 3-amino-3-arylpropionic acid analogs of thalidomide that are potent inhibitors of tumor necrosis factor-alpha are reported. These compounds were found to be potent inhibitors of phosphodiesterase 4.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1998

NRG-3 in human breast cancers: activation of multiple erbB family proteins.

Ligands of the EGF/Heregulin family control the growth of epithelial cells by binding to receptors of the erbB family. By searching a large database of cDNA sequences at Human Genome Sciences Inc. we have identified a new encoded protein sequence containing all the conserved elements of the EGF/Heregulin family. The same sequence has recently been independently identified as NRG-3. The EGF-like domain of NRG-3 was generated as a recombinant protein in E. coli and used to test the specificity of receptor binding. In human breast cancer cells and in 32D cells transfected by erbB family members, NRG-3 activated multiple erbB family members. These include EGF receptor (erbB1) and erbB4 when expressed individually and erbB2 and erbB3 when expressed together. Recombinant NRG-3 altered the growth of human breast cancer cells growing in vitro. NRG-3 was expressed in cell lines derived from breast cancer. These results indicate that NRG-3 is a potential regulator of normal and malignant breast epithelial cells in vivo.

Amino Acid Sequence↗
PubMed1997

The cost of dying of end-stage liver disease.

BACKGROUND: The high cost of liver transplantation is well known. The cost of dying of complications of end-stage liver disease (ESLD) without transplant, however, has not been well documented. METHODS: For a 5-year period (1991-1995), in 153 patients, mean inpatient hospital charges and length of stay were analyzed in 6 groups of patients: (1) patients admitted with the primary diagnosis of esophageal varices, (1a) the subset of group 1 patients who died on this admission, (2) patients admitted to the liver team who died of complications from ESLD, (3) patients who underwent transjugular intrahepatic portosystemic shunts, (4) patients who underwent surgical shunt for bleeding varices, and (5) patients who underwent liver transplantation. RESULTS: One hundred twenty-nine patients with esophageal varices were hospitalized 13.7 days with a mean charge of $30,980 for each of 202 admissions. Of these, 38 died after 24 days with a mean charge of $67,091. Seven patients admitted to the liver team died of complications of ESLD at $110,576 per admission. Transjugular intrahepatic portosystemic shunt was performed in 17 patients with a mean charge of $43,209. Six patients underwent surgical shunt for $53,994. Mean charge for 7 liver transplantations was $222,968. During the study period, 36.7% of all charges were for patients who died. CONCLUSIONS: It is difficult to estimate the total cost of ESLD; however, in evaluating inpatient costs, we see that it is expensive and significant amounts are spent on patients who die. Further study is necessary to determine which factors can optimize the cost of ESLD.

Adult↗
PubMed1997

Organization and differential expression of the human monocyte chemoattractant protein 1 receptor gene. Evidence for the role of the carboxyl-terminal tail in receptor trafficking.

Two forms of the monocyte chemoattractant protein-1 receptors (the type A monocyte chemoattractant protein 1 (MCP-1) receptor CCR-2A and the type B MCP-1 receptor (CCR-2B) have been recently cloned and found to differ only in their terminal carboxyl tails. Here, we report that the two isoforms are alternatively spliced variants of a single MCP-1 receptor gene. Sequencing of the gene revealed that the 47-amino acid carboxyl tail of CCR2B was located in the same exon as the seven transmembrane domains of the receptor, and the 61-amino acid tail of CCR2A was in a downstream exon. Examination of freshly isolated human monocytes by reverse transcriptase-polymerase chain reaction revealed that CCR2B was the predominant isoform and that message levels of both CCR2A and CCR2B decreased as the monocytes differentiated into macrophages. In stably transfected cell lines, CCR2B trafficked well to the cell surface, but CCR2A was found predominantly in the cytoplasm. Equilibrium binding studies revealed that those CCR2A receptors that successfully trafficked to the cell surface bound MCP-1 with high affinity (Kd = 310 pM), similar to CCR2B. In signaling studies, both CCR2A and CCR2B mediated agonist-dependent calcium mobilization, as well as inhibition of adenylyl cyclase. Creation of chimeras between CCR2A and the human thrombin receptor revealed that the cytoplasmic retention of CCR2A was due to its terminal carboxyl tail. Progressive truncation of the carboxyl tail indicated that a cytoplasmic retention signal(s) was located between residues 316 and 349. These data indicate that the alternatively spliced form of the human MCP-1 receptor (CCR2A) binds MCP-1 with high affinity and is a functional receptor and that expression at the cell surface is controlled by amino acid sequences located in the terminal carboxyl tail.

Amino Acid Sequence↗
PubMed1997

Calciphylaxis in patients on hemodialysis: a prevalence study.

BACKGROUND: Calciphylaxis is characterized by painful, violaceous, mottled skin lesions (livedo reticularis) that may progress to tissue necrosis, nonhealing ulcers, gangrene, and potentially amputation, sepsis, or death. The prevalence and characteristics of patients who have calciphylaxis need further identification to predict which patients on dialysis may benefit from close monitoring or early surgical intervention. METHODS: All 242 patients undergoing hemodialysis in an outpatient unit were reviewed retrospectively during a 15-month cross-sectional study of the prevalence and characteristics of calciphylaxis. RESULTS: Ten patients (prevalence, 4.1%) had calciphylaxis. Patients with calciphylaxis were significantly younger (49 versus 60 years; p = 0.01), had undergone hemodialysis longer (80 versus 20 months; p < 0.0001), and had higher median serum calcium (9.7 versus 9.2 mg/dl; p = 0.03), phosphate (8.2 versus 5.7 mg/dl; p = 0.001), calcium phosphate product (81.5 versus 52.9; p = 0.0004), parathyroid hormone (1496 versus 138 pg/ml; p < 0.0001), and alkaline phosphatase levels (188 versus 89 IU/L; p = 0.0001). Bone surveys were positive in all 10 patients with calciphylaxis compared with 49 (21%) of the 232 patients without calciphylaxis (p < 0.0001). All patients who underwent parathyroidectomy for calciphylaxis had dramatic healing of the ulcers. CONCLUSIONS: The presence of calciphylaxis is higher among younger patients who had undergone longer periods of hemodialysis. Therefore this group of patients should be monitored aggressively and treated expeditiously for complications of secondary hyperparathyroidism.

Adult↗
PubMed1997

Multi-center sestamibi parathyroid imaging study in Hawaii.

Technetium-99m (99mTc) sestamibi (MIBI) was first used as a parathyroid imaging agent in Hawaii in 1991. The purpose of this study was to determine the sensitivity and positive predictive value of the MIBI scan in detecting abnormal parathyroid glands. A retrospective, multi-center study from 1992-1994 involving 33 patients in four hospitals showed the overall sensitivity of the MIBI scan for detecting hyperparathyroid disease was 90%. The positive predictive value was 93%. It was more sensitive in detecting adenomas (95%) than hyperplasia (45%). In conclusion, the MIBI scan can be helpful in detecting abnormal parathyroid glands and may be most useful prior to reoperations for persistent and recurrent hyperparathyroidism.

Adenoma↗
PubMed1996

DNA elements responsive to auxin.

Genes induced by the plant hormone auxin are probably involved in the execution of vital cellular functions and developmental processes. Experimental approaches designed to elucidate the molecular mechanisms of auxin action have focused on auxin perception, genetic dissection of the signaling apparatus and specific gene activation. Auxin-responsive promoter elements of early genes provide molecular tools for probing auxin signaling in reverse. Functional analysis of several auxin-specific promoters of unrelated early genes suggests combinatorial utilization of both conserved and variable elements. These elements are arranged into autonomous domains and the combination of such modules generates uniquely composed promoters. Modular promoters allow for auxin-mediated transcriptional responses to be revealed in a tissue- and development-specific manner.

Base Sequence↗
PubMed1996

Differential activation of the primary auxin response genes, PS-IAA4/5 and PS-IAA6, during early plant development.

The plant growth hormone auxin typified by indoleacetic acid (IAA) transcriptionally activates early genes in pea, PS-IAA4/5 and PS-IAA6, that are members of a multigene family encoding short-lived nuclear proteins. To gain first insight into the biological role of PS-IAA4/5 and PS-IAA6, promoter-beta-glucuronidase (GUS) gene fusions were constructed and their expression during early development of transgenic tobacco seedlings was examined. The comparative analysis reveals spatial and temporal expression patterns of both genes that correlate with cells, tissues, and developmental processes known to be affected by auxin. GUS activity in seedlings of both transgenic lines is located in the root meristem, sites of lateral root initiation and in hypocotyls undergoing rapid elongation. In addition, mutually exclusive cell-specific expression is evident. For instance, PS-IAA4/5-GUS but not PS-IAA6-GUS is expressed in root vascular tissue and in guard cells, whereas only PS-IAA6-GUS activity is detectable in glandular trichomes and redistributes to the elongating side of the hypocotyl upon gravitropic stimulation. Expression of PS-IAA4/5 and PS-IAA6 in elongating, dividing, and differentiating cell types indicates multiple functions during development. The common and yet distinct activity patterns of both genes suggest a combinatorial code of spatio-temporal co-expression of the various PS-IAA4/5-like gene family members in plant development that may mediate cell-specific responses to auxin.

Cell Differentiation↗