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Biomedical subjects

M L Wong

Publications and source records attributed to M L Wong.

At least 37 records · Page 2Linked to original sources
PubMed2002

Effluents from a pulp and paper mill: a skin and health survey of children living in upstream and downstream villages.

OBJECTIVES: A health survey of three villages (upstream village Rantau Baru and two downstream villages, Sering and Pelalawan) in the vicinity of a pulp and paper mill along the Kampar river in the province of Riau, Indonesia was conducted to find whether exposure to the effluents from the mill was related to skin conditions and ill health. METHODS: A cross sectional survey was carried out of children living in the three villages. RESULTS: Common skin conditions such as dermatitis, fungal infections, insect bites, and miliaria were found. No significantly increased risk of dermatitis or any illness in general was found with increasing levels of exposure to river water for downstream villages when compared with the upstream village. However, there was an increased risk of diarrhoea in Sering especially with drinking water directly from the river (prevalence rate ratio (PRR) 4.9, 95% confidence interval (95% CI) 0.4 to 63.9). An increased risk was also found within the upstream village Rantau Baru (PRR 2.3, 95% CI 0.9 to 5.8) and downstream village Sering (PRR 1.4, 95% CI 0.4 to 5.2) when children who drank water directly from the river were compared with those who never did. Analysis of the river water also showed physical and chemical variables within the acceptable range except for faecal coliforms (6 MPN/100 ml) found in the sample taken from Sering. CONCLUSIONS: The effluent from the mill is unlikely to be causing skin conditions and ill health. Diarrhoea may be due to faecal coliform contamination of the water because all raw sewerage is deposited in the river. Community health outreach programmes are being implemented based on these findings.

Child↗
PubMed2002

Prevalence of prostatitis-like symptoms in Singapore: a population-based study.

OBJECTIVE: To study the prevalence of prostatitis-like symptoms in a generally healthy population. SUBJECTS AND METHODS: A population-based cross-sectional survey was conducted in Singapore to evaluate "prostatitis-like symptoms" (PS), lower urinary tract symptoms (LUTS),erectile dysfunction (ED), and quality of life (QoL). Respondents with pain or discomfort in the perineum, testicles, tip of penis or bladder/suprapubic region were identified as having prostatitis-like symptoms. RESULTS: Altogether, 1087 males aged 21 to 70 were evaluated. While at least 20% of them had some degree of LUTS, only 2.67% (29 out of 1087) had pain or discomfort suggestive of prostatitis. Six men had pain in the bladder or suprapubic region, two in the perineum, six at the tip of penis and 26 had pain during micturition (11 subjects had more than one location of pain). Only two men had severe pain while seven had moderate and the rest had mild pain. The mean age of subjects with PS was 43.14. In terms of racial distribution, 2.23% (18) of Chinese, 3.15% (4) of Malay, 4.49% (4) of Indians and 12.12% (3) of other ethnic origin had PS. Those who had PS had worse erectile function (International Index of Erectile Function (IIEF) 11.92 vs. 17.16, p < 0.003) and a worse QoL score (2.96 vs. 1.38, p < 0.001) than those without PS. Those with PS were more bothered and worried about their symptoms. CONCLUSION: The prevalence of prostatitis-like symptoms in a largely Chinese population is 2.67%. Prostatitis-like symptoms have a negative impact on the quality of life and erectile function.

Adult↗
PubMed2002

Evidence-based health promotion: applying it in practice.

INTRODUCTION: In health promotion, we should use interventions established by evidence to be effective in improving the health of the community. This paper reviews the concepts, evaluation and use of evidence in health promotion. METHODS: A literature search of evidence-based health promotion and evaluation of health promotion was conducted using Medline, Social Science Citation Index (SSCI), PsycLIT and evidence-based web sites on health promotion, health education and community preventive services. Recent issues of key journals on health promotion, health education and public health were also hand-searched. RESULTS: The concept of evidence in health promotion interventions is complex due to its multidimensional nature. Evidence of effectiveness in health promotion is assessed by combining quantitative data on effect change in outcome measures and qualitative data on process evaluation of health promotion activities. Limitations to the use of randomised trials in community-based health promotion interventions include ethical and logistic problems in maintaining randomisation of subjects over long periods, absence of experimental conditions in the real-world setting, contamination of control subjects and the multidimensional nature of health promotion interventions. CONCLUSION: Randomised controlled trials should be used to evaluate the effectiveness of most health education and behavioural interventions in clinical settings. When such trials are not feasible as in community-based health promotion interventions, quasi-experimental designs provide strong evidence. Multiple methods are needed to assess evidence of effectiveness of health promotion programmes. Appropriate practice of evidence-based health promotion requires consideration of quality of available evidence, local values and prevailing resources.

Evidence-Based Medicine↗
PubMed2001

IL-1 receptor type I gene expression in the amygdala of inflammatory susceptible Lewis and inflammatory resistant Fischer rats.

Lewis (LEW/N) and Fischer (F344/N) rats have different responses to inflammatory and behavioral stressors due to differences in hypothalamus-pituitary-adrenal (HPA) axis function. For example, LEW/N rats are more sensitive to restraint, inflammation and experimentally induced autoimmunity due to decreased HPA activity. The HPA axis response to peripheral inflammation is mediated, at least in part, by IL-1beta and its receptor, IL-1 type I (IL-1RI). Here, we studied the distribution of IL-1RI mRNA in the brains of LEW/N and F344/N rats, and demonstrated that IL-1RI mRNA expression has significantly increased in the basolateral nucleus (BLA) of the amygdala of LEW/N rats. These findings suggest that strain-specific HPA axis responses may be mediated by extrahypothalamic pathways.

Amygdala↗
PubMed2001

Cloning and sequencing of full-length cDNA of classical swine fever virus LPC strain.

The cDNAs of classical swine fever virus (LPC vaccine strain) were cloned by transcriptase-polymerase chain reaction, and their nucleotide sequences were determined. In this work, we obtained the sequence information of the 786 bases of the 5'-terminal region, 6049 bases of the middle region, and 1648 bases of the 3'-terminal region. Taking our previous results and present data together, the entire genomic sequence of LPC strain was completed (12344 nucleotides in length). The genome of LPC has a large open reading frame that can encode a polypetide of 3897 amino acids, and are flanked by untranslated regions (UTR), 373 bases at the 5'-end and 278 bases at the 3'-end. Phylogenetic analysis based on genomic sequences of several viruses suggested that the LPC strain is closer to Chinese, Riems, HCLV, Alfort/187, Brescia, and Alfort strains in order. After further analysis, we found that an insertion of 13 nucleotides, TTT(C/T)CTTTTTTTT, in the 3'-UTR of LPC, Chinese, and HCLV strains. Immediately downstream to the 13 nucleotides, a unique sequence of LPC consisting of 28 thymidine was observed.

Base Sequence↗
PubMed2001

Research and treatment approaches to depression.

Depression is a major cause of disability worldwide, but we know little about the underlying fundamental biology. Research is hindered by the difficulties of modelling a disorder of higher cognitive functions in animals. Depression can be understood as the interaction of genetic susceptibility and environmental factors; however, current classifications are purely descriptive. The complexity of this field is best approached by rigorous explorations of known candidate systems in conjunction with the use of genomic tools to discover new targets for antidepressants and to predict therapeutic outcomes.

Animals↗
PubMed2001

Expression of corticotropin releasing hormone receptors type I and type II mRNA in suicide victims and controls.

Corticotropin-releasing hormone (CRH) is a key neuroendocrine factor implementing endocrine, immune and behavioral responses to stress. CRH exerts its action through two major receptors, CRH-R1 and CRH-R2. Recently novel non-peptidic antagonists directed against CRH-R1 or CRH-R2 have been proposed as promising agents in the treatment of depression, anxiety and eating disorder. However, so far the CRH-receptor system has not been widely studied in humans. Therefore, we employed quantitative TaqMan PCR to analyze the expression and distribution of both CRH-R1 and CRH-R2 in human brain tissue and peripheral organs. Furthermore the expression of CRH receptors was analyzed for the first time in pituitaries of suicide victims by in situ hybridization and quantitative PCR. Our data demonstrated a different expression pattern in humans as compared to rodents. Both CRH-R1 and CRH-R2 were expressed in high amounts in the brain with the strongest expression in the pituitary. As described in rodents, however the CRH-R1 in human was the predominant receptor in the brain (82.7 +/- 11.0%), whilst CRH-R2 was the predominant receptor in peripheral organs (77.0 +/- 15.8%). There was a shift in the ratio of CRH-R1/R2 in the pituitaries of suicide victims. In conclusion, both CRH-R1 and CRH-R2 are widely expressed in human tissues with a distribution substantially different from rodents. Strong expression of both CRH-R1 and CRH-R2 in human pituitaries suggests that particularly under stress, activation of the HPA axis can be maintained through both receptors.

Adolescent↗
PubMed2001

Single nucleotide polymorphism identification in candidate gene systems of obesity.

We have constructed a large panel of single nucleotide polymorphisms (SNP) identified in 68 candidate genes for obesity. Our panel combines novel SNP identification methods based on EST data, with public SNP data from largescale genomic sequencing, to produce a total of 218 SNPs in the coding regions of obesity candidate genes, 178 SNPs in untranslated regions, and over 1000 intronic SNPs. These include new non-conservative amino acid changes in thyroid receptor beta, esterase D, acid phosphatase 1. Our data show evidence of negative selection among these polymorphisms implying functional impacts of the non-conservative mutations. Comparison of overlap between SNPs identified independently from EST data vs genomic sequencing indicate that together they may constitute about one half of the actual total number of amino acid polymorphisms in these genes that are common in the human population (defined here as a population allele frequency above 5%). We have analyzed our polymorphism panel to construct a database of detailed information about their location in the gene structure and effect on protein coding, available on the web at http://www.bioinformat ics.ucla.edu/snp/obesity. We believe this panel can serve as a valuable new resource for genetic and pharmacogenomic studies of the causes of obesity.

Databases, Genetic↗
PubMed2001

PEG adsorption of autoantibodies and detection of alloantibodies in warm autoimmune hemolytic anemia.

BACKGROUND: The purpose of this study was to evaluate the effectiveness of PEG in the adsorption of autoantibodies and the detection of alloantibodies in patients with warm autoimmune hemolytic anemia (WAIHA). STUDY DESIGN AND METHODS: The study was divided into three parts. First, the effectiveness of antibody removal by a conventional adsorption procedure and that by the PEG adsorption method were compared by using commercial antisera adsorbed with antigen-positive RBCs. Second, patients' sera with known weak alloanti-E were used to test against screening cells after allogeneic adsorption to show nonspecific coating of antibodies and the dilution effect on the PEG adsorption procedure. Third, conventional and PEG one-cell sample allogeneic adsorptions of WAIHA patients' sera with and without alloantibodies were performed and compared. RESULTS: In the first part, seven of the eight polyclonal antisera gave a lower titer and score when tested against antigen-positive RBCs in the indirect antiglobulin test; this indicated that PEG is more efficient in removing antibodies. In the second part, similar reaction patterns were observed in antibody screening tests on unadsorbed sera and on sera after the first, second, and third adsorptions, which indicated that there was no alloantibody loss, nonspecific antibody coating, or dilution effect when PEG was added in the allogeneic adsorption procedures. In the third part, a 40-percent increase in efficiency in reducing the number of adsorptions and an 85-percent decrease in completion time of the adsorption procedures were obtained when PEG was used for adsorbing sera from 16 patients with WAIHA. Both conventional and PEG procedures were capable of removing autoantibodies to identify the specificities of alloantibodies. CONCLUSION: The PEG adsorption method is an effective, sensitive, and efficient method of enhancing auto- antibody adsorption and alloantibody detection. It can reduce the processing time and minimize the delay of urgent transfusions to patients with WAIHA and can indirectly enhance cost-effectiveness and decrease the labor-intensive testing required by these cases.

Anemia, Hemolytic↗
PubMed2001

Synchronicity of frequently sampled thyrotropin (TSH) and leptin concentrations in healthy adults and leptin-deficient subjects: evidence for possible partial TSH regulation by leptin in humans.

Leptin signals the status of energy reserves to the brain. Leptin stimulates biosynthesis of TRH in vitro and influences the activity of the hypothalamic-pituitary-thyroid axis in vivo in rodents. Because blood levels of both leptin and TSH display diurnal variation with a distinct nocturnal rise, we sought to determine whether a relationship exists between fluctuations in circulating leptin and TSH. We measured serum leptin and TSH levels every 7 min for 24 h in five healthy men and found that both leptin and TSH levels are highly organized and pulsatile. A similar pattern of leptin and TSH rhythms was observed, with TSH and leptin levels reaching a nadir in late morning and a peak in the early morning hours. Importantly, cosinor analysis on the absolute leptin and TSH levels revealed a statistically significant fit for a 24-h period and the two hormones showed similar probabilities of rhythm and superimposable peak values. Furthermore, this study shows a strong positive Pearson correlation between the 24-h patterns of variability of leptin and TSH in healthy subjects. Finally, the ultradian fluctuations in leptin levels showed pattern synchrony with those of TSH as determined by cross-correlation analysis, by cross-approximate enthropy and Bayessian analysis applied independently. To further explore whether these associations could reflect an underlying regulation of TSH secretion by leptin, we also studied frequently sampled leptin and TSH levels in four brothers, members of a family with leptin deficiency (one normal homozygote, two heterozygotes, and one leptin-deficient homozygote). Leptin levels of the homozygous leptin-deficient subject are detectable but bioinactive, and the rhythm of his TSH is disorganized. 24-h pattern of leptin and TSH variability in the heterozygous subjects, although significantly correlated, showed a weaker correlation compared with the strong correlation in the normal subjects. These data are consistent with the possibility that leptin may regulate TSH pulsatility and circadian rhythmicity, but interventional studies are needed to definitively prove whether leptin regulates the minute-to-minute oscillations and ultradian rhythm of TSH levels.

Adult↗
PubMed2001

Transcranial Doppler identification of changing autoregulatory thresholds after autoregulatory impairment.

OBJECTIVE: Transcranial Doppler (TCD) flow velocity (FV) assessment may provide a useful index of autoregulatory impairment after severe head injury. It may define a therapeutic end point against which cerebral perfusion pressure (CPP) can be titrated. This study examines the relationship between cerebral blood flow (CBF) and TCD FV indices in a laboratory model before and after autoregulatory impairment. METHODS: CPP, CBF, and middle cerebral artery TCD FV were measured continuously in nine anesthetized and ventilated sheep. CPP was decreased by hemorrhagic hypotension. The process was repeated after impairment of autoregulation by cisternal infusion, which maintained CPP at 0 mm Hg for 15 minutes. Points of significant change (i.e., breakpoints) from baseline values for each of the measured flow parameters were identified by using a ratio of variance technique. RESULTS: Before any significant change in CBF or systolic TCD, diastolic TCD FV decreased (mean breakpoint, 69 mm Hg; range, 56-78 mm Hg) as CPP was reduced. This divergence of diastolic and systolic TCD FV, which occurred before autoregulatory failure, was associated with an increasing TCD pulsatility index (mean breakpoint, 63 mm Hg; range, 53-70 mm Hg). At diastolic TCD FV congruent with 10 cm/s, systolic TCD FV (mean breakpoint, 48 mm Hg; range, 46-53 mm Hg) and CBF (mean breakpoint, 49 mm Hg; range, 47-51 mm Hg) decreased rapidly, indicating autoregulatory failure. After autoregulatory impairment, the breakpoints for all four indices shifted to higher CPP values (mean, 16 mm Hg). CONCLUSION: TCD FV assessment identified two CPP thresholds of autoregulatory loss. Before autoregulatory failure, an earlier phase of autoregulatory disturbance may be detected by divergent systolic and diastolic TCD FVs. It is important to note that this phase may be detected before CBF decreases. These TCD FV breakpoints depend on the state of autoregulatory impairment and may provide potential targets for CPP-directed therapy.

Animals↗
PubMed2001

A case series of six children with primary pulmonary hypertension.

INTRODUCTION: Primary pulmonary hypertension is an uncommon but serious disease in children. Management is difficult despite recent advances in pharmacotherapy. CLINICAL PICTURE: We reviewed patients with this condition with respect to their presenting symptoms, investigations, treatment and outcome. TREATMENT: These children were treated with individualised combinations of oxygen, diuretics and calcium antagonists. OUTCOME: In our follow-up of 5 children, 4 had died. CONCLUSION: This condition is irreversible and progressive with a high mortality rate. A better understanding of, and research into, the pathogenesis would hopefully lead to the formulation of improved therapeutic strategies for this condition.

Adolescent↗
PubMed2000

Persistent alterations in dendrites, spines, and dynorphinergic synapses in the nucleus accumbens shell of rats with neuroleptic-induced dyskinesias.

Chronic treatment of humans or experimental animals with classical neuroleptic drugs can lead to abnormal, tardive movements that persist long after the drugs are withdrawn. A role in these neuroleptic-induced dyskinesias may be played by a structural change in the shell of the nucleus accumbens where the opioid peptide dynorphin is upregulated in treated rats that show vacuous chewing movements (VCMs). The shell of the nucleus accumbens normally contains a dense plexus of dynorphinergic fibers especially in its caudomedial part. After 27 weeks of haloperidol administration and 18 weeks of withdrawal, the immunoreactive labeling of this plexus is intensified when compared with that after vehicle treatment. In addition, medium spiny neurons here show a significant increase in spine density, dendritic branching, and numbers of terminal segments. In the VCM-positive animals, the dendritic surface area is reduced, and dynorphin-positive terminals contact more spines and form more asymmetrical specializations than do those in animals without the syndrome (VCM-negative and vehicle-treated groups). Persistent, neuroleptic-induced oral dyskinesias could therefore be caused by incontrovertible alterations, involving terminal remodeling or sprouting, to the synaptic connectivity of the accumbal shell.

Animals↗
PubMed2000

Acute systemic inflammation up-regulates secretory sphingomyelinase in vivo: a possible link between inflammatory cytokines and atherogenesis.

Inflammation plays a critical role in atherogenesis, yet the mediators linking inflammation to specific atherogenic processes remain to be elucidated. One such mediator may be secretory sphingomyelinase (S-SMase), a product of the acid sphingomyelinase gene. The secretion of S-SMase by cultured endothelial cells is induced by inflammatory cytokines, and in vivo data have implicated S-SMase in subendothelial lipoprotein aggregation, macrophage foam cell formation, and possibly other atherogenic processes. Thus, the goal of this study was to seek evidence for S-SMase regulation in vivo during a physiologically relevant inflammatory response. First, wild-type mice were injected with saline or lipopolysaccharide (LPS) as a model of acute systemic inflammation. Serum S-SMase activity 3 h postinjection was increased 2- to 2.5-fold by LPS (P < 0.01). To determine the role of IL-1 in the LPS response, we used IL-1 converting enzyme knockout mice, which exhibit deficient IL-1 bioactivity. The level of serum S-SMase activity in LPS-injected IL-1 converting enzyme knockout mice was approximately 35% less than that in identically treated wild-type mice (P < 0.01). In LPS-injected IL-1-receptor antagonist knockout mice, which have an enhanced response to IL-1, serum S-SMase activity was increased 1. 8-fold compared with LPS-injected wild-type mice (P < 0.01). Finally, when wild-type mice were injected directly with IL-1beta, tumor necrosis factor alpha, or both, serum S-SMase activity increased 1. 6-, 2.3-, and 2.9-fold, respectively (P < 0.01). These data show regulation of S-SMase activity in vivo and they raise the possibility that local stimulation of S-SMase may contribute to the effects of inflammatory cytokines in atherosclerosis.

Acute Disease↗
PubMed2000

Pronounced and sustained central hypernoradrenergic function in major depression with melancholic features: relation to hypercortisolism and corticotropin-releasing hormone.

Both stress-system activation and melancholic depression are characterized by fear, constricted affect, stereotyped thinking, and similar changes in autonomic and neuroendocrine function. Because norepinephrine (NE) and corticotropin-releasing hormone (CRH) can produce these physiological and behavioral changes, we measured the cerebrospinal fluid (CSF) levels each hour for 30 consecutive hours in controls and in patients with melancholic depression. Plasma adrenocorticotropic hormone (ACTH) and cortisol levels were obtained every 30 min. Depressed patients had significantly higher CSF NE and plasma cortisol levels that were increased around the clock. Diurnal variations in CSF NE and plasma cortisol levels were virtually superimposable and positively correlated with each other in both patients and controls. Despite their hypercortisolism, depressed patients had normal levels of plasma ACTH and CSF CRH. However, plasma ACTH and CSF CRH levels in depressed patients were inappropriately high, considering the degree of their hypercortisolism. In contrast to the significant negative correlation between plasma cortisol and CSF CRH levels seen in controls, patients with depression showed no statistical relationship between these parameters. These data indicate that persistent stress-system dysfunction in melancholic depression is independent of the conscious stress of the disorder. These data also suggest mutually reinforcing bidirectional links between a central hypernoradrenergic state and the hyperfunctioning of specific central CRH pathways that each are driven and sustained by hypercortisolism. We postulate that alpha-noradrenergic blockade, CRH antagonists, and treatment with antiglucocorticoids may act at different loci, alone or in combination, in the treatment of major depression with melancholic features.

Adrenocorticotropic Hormone↗