Tissue microarray study for classification of breast tumours.
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Breast↗
Biomedical subjects
E S Koay
Publications and source records attributed to E S Koay.
Compound heterozygous familial hypercholesterolemia and familial defective apolipoprotein B-100 produce exaggerated hypercholesterolemia.
BACKGROUND: Familial hypercholesterolemia (FH) and familial defective apolipoprotein B-100 (FDB) represent ligand-receptor disorders that are complementary. Individuals with both FH and FDB are unusual. We report a family with both disorders and the impact of the mutations on the phenotypes of the family members. METHODS: We used single strand conformation polymorphism (SSCP) and denaturing gradient gel electrophoresis (DGGE) for genetic analysis of all 18 exons and the promoter region of the LDL receptor and DGGE for genetic analysis of the apolipoprotein B-100 (apo B-100) gene. The functional significance of the apo B-100 mutation was studied using a U937 cell proliferation assay. Fasting serum lipid profiles were determined for the index case and seven first-degree relatives. RESULTS: One of the patient's sisters had a missense mutation (Asp(407)-->Lys) in exon 9 of the LDL receptor and a serum LDL-cholesterol concentration of 4.07 mmol/L. Four other first-degree relatives had hyperlipidemia but no LDL-receptor mutation. However, these subjects had a mutation of the apo B-100 gene (Arg(3500)-->Trp). The cell proliferation rate of U937 cells fed with LDL from other subjects with the same mutation was fourfold less than that of controls. The index case had both FH- and FDB-related mutations. Her serum LDL-cholesterol (9.47 mmol/L) was higher than all other relatives tested. CONCLUSIONS: Existence of both FH and FDB should be considered in families with LDL-receptor mutations in some but not all individuals with hypercholesterolemia or when some individuals in families with FH exhibit exaggerated hypercholesterolemia.
Adolescent↗
Prevalence of primary aldosteronism among Asian hypertensive patients in Singapore.
Recent studies using the ratio of plasma aldosterone concentration (PAC) to PRA as the screening test for primary aldosteronism in hypertensive populations suggested that the prevalence may be as high as 5-15%, with well over half of the subjects having normal serum potassium concentrations. Despite an increasing clinical awareness of this entity, many clinicians are reluctant to consider routine screening for primary aldosteronism in essential hypertensive patients because there are few community-based prevalence studies of primary aldosteronism in different populations. Furthermore, genetic and environmental differences may affect the prevalence and presentation of primary aldosteronism in distinct populations. This study was designed to determine the prevalence of primary aldosteronism in the predominantly Chinese population in Singapore. Three hundred and fifty unselected adult hypertensive patients attending two primary care clinics had random ambulatory measurements for PAC (nanograms per dL) and PRA (nanograms per mL/h). Serum urea, creatinine, and electrolyte measurements were obtained simultaneously. Subjects with renal insufficiency (serum creatinine, >140 micromol/L) and those treated with glucocorticoids or spironolactone were excluded. Screening was considered positive if the PAC: PRA ratio was more than 20 and the PAC was more than 15 ng/dL (>416 pmol/L). Primary aldosteronism was confirmed with the determination of PAC after 2 L saline administered iv over 4 h. Adrenal computed tomographic (CT) scans were performed in biochemically confirmed cases of primary aldosteronism. Further localization with adrenal vein sampling was carried out in selected patients with equivocal findings on adrenal CT scan. Sixty-three (18%) of the 350 hypertensive patients (215 women and 135 men; age range, 23-75 yr) were screened positive for primary aldosteronism. Only 13 of these 63 subjects (21%) were hypokalemic (serum potassium, <3.5 mmol/L). Confirmatory studies were carried out in 56 (89%) of the subjects with a positive PAC:PRA ratio. Using a PAC above 10 ng/dL (>277 pmol/L) after saline infusion as the diagnostic cut-off, 16 of the 56 patients had biochemically confirmed primary aldosteronism. Hypokalemia was found in 6 of the 16 patients (37.5%) with primary aldosteronism. Subtype evaluation with adrenal CT scan and adrenal vein sampling indicated that half of the patients with primary aldosteronism may have had potentially curable unilateral adrenal adenoma. Our data suggest that primary aldosteronism occurs in at least 5% of the adult Asian hypertensive population, and approximately half of these individuals may have potentially curable, unilateral, aldosterone-producing adrenal adenoma. Our findings also confirm the poor predictive value of hypokalemia in both the diagnosis and the exclusion of primary aldosteronism.
Adult↗
Apolipoprotein B 5'-Ins/Del and 3'-VNTR polymorphisms in Chinese, malay and Indian singaporeans.
The allele frequencies for the apolipoprotein B (apo B) 5'-Ins/Del and 3'-VNTR polymorphisms varied significantly (p < 0.01) among Singaporeans of Chinese, Malay and Indian descent. We calculated the unbiased expected heterozygosities for the 5'-Ins/Del polymorphism as 0.3357, 0.1984 and 0.2418, and for the 3'-VNTR as 0.5980, 0.5260 and 0.6749, respectively, in the Chinese, Malays and Indians. Compared to heterozygosities reported for other populations, the Singaporeans differed from most Caucasians in having significantly lower values but were closely related to other non-Caucasians. Thirteen alleles, with a bimodal distribution, were observed at the 3'-VNTR polymorphic locus; the alleles occurring most frequently among the Chinese and Malays were of 35 or 53 repeats, and among the Indians, of 37 or 47 repeats. The Del allele was associated with elevated serum cholesterol (p = 0.023), LDL-cholesterol (LDL-C) (p = 0.001) in the Chinese, and apo B (p = 0.007) in the Indians. Likewise, the larger 3'-VNTR alleles (> 41 repeats) were associated with raised cholesterol (p = 0.018), LDL-C (p = 0.025), and triglyceride (p = 0.001) in the Chinese. The two polymorphisms were not in significant linkage disequilibrium (D = -0.0029, p = 0.494) in the three ethnic groups.
Adult↗
Effects of intragenic variability at 3 polymorphic sites of the apolipoprotein B gene on serum lipids and lipoproteins in a multiethnic Asian population.
We determined the allelic (X+/X-, M+/M-, and E+/E-) distribution frequencies of the XbaI, MspI, and EcoRI restriction fragment length polymorphisms (RFLPs) in the apolipoprotein B gene in a control group of 374 healthy Chinese, Malays, and Indians and in a hyperlipidemic cohort of 131 Chinese patients. Covariability between the RFLPs and serum lipid, lipoprotein, and apolipoprotein concentrations was also studied. We found a lower frequency (average 0.0829) of the X+ allele and higher frequencies of the E+ (average 0.9452) and M+ (average 0.9772) alleles in our study population compared with frequencies reported in other populations. The 3 polymorphic sites did not contribute to significant variations in lipid levels (p > 0.1 in all cases). Also, there was no significant variation in genotype frequencies between the control subjects and the hyperlipidemic subjects. Despite their relative close proximity within the APOB gene sequence, the 3 polymorphic sites did not show any significant linkage disequilibrium. However, the presence of the X+ cutting site was in linkage disequilibrium with the Del allele of the 5' insertion-deletion polymorphism and the E-allele was in linkage disequilibrium with the 3' VNTR located near the 3' end of the coding region of the APOB gene.
Adolescent↗
The StuI polymorphism on exon 8 of the low density lipoprotein (LDL) receptor gene: prevalence and impact on serum lipid levels in an Asian cohort.
A single nucleotide (A-->G) substitution in codon 370 (exon 8) of the low density lipoprotein (LDL) receptor gene results in loss of a StuI restriction site and an amino acid change (Ala370-->Thr) in the translated protein. This biallelic polymorphism has been associated with significant variations in plasma lipid concentrations in several Caucasian populations. We investigated its prevalence and impact on lipid metabolism in 539 Singaporeans of Chinese, Malay and Indian descent. The average frequency of 0.003 for the Thr370 allele and heterozygosity of 0.0056 were 10- to 20-fold lower than those reported in Caucasians (range 0.075 to 0.107). Distribution of the genotypes satisfied the Hardy-Weinberg equilibrium (chi 2 = 0.004, P = 0.948). We also found ethnic variation in the allele frequencies of Thr370 among the three races studied (0.009 in Indians, 0.007 in Malays, and 0.003 in Chinese). However, this needs to be confirmed with larger numbers. No significant correlation between genotype and serum concentrations of total cholesterol, triglyceride, high density lipoprotein (HDL)-cholesterol, LDL-cholesterol, lipoprotein(a), apolipoprotein A and apolipoprotein B was found in our study. This argues strongly against a major contribution or impact of this intragenic polymorphic locus on modulating the serum lipid profiles of the study subjects.
Adolescent↗
Denaturing gradient-gel electrophoresis screening of familial defective apolipoprotein B-100 in a mixed Asian cohort: two cases of arginine3500-->tryptophan mutation associated with a unique haplotype.
The Arg-to-Trp substitution at codon 3500 in the apolipoprotein (apo) B-100 gene is established as a cause of familial defective apo B-100 (FDB), a functional mutation, resulting in reduced LDL receptor binding and manifest hypercholesterolemia. In a search for similar mutations in 163 Malaysians, we screened the putative receptor-binding region (codons 3456-3553) of the apo B-100 gene by PCR amplification and denaturing gradient-gel electrophoresis. Four single-base mutations were detected and confirmed by DNA sequencing. Two females, a Chinese and a Malay, had the same CGG3500-->TGG mutation, resulting in an Arg3500-to-Trp substitution. This is the second published report of such an independent mutation involving the same codon as the established Arg3500-to-Gln mutation. The two other mutations detected, CTT3517-->CTG and GCC3527-->GCT, resulted in degenerate codons with no amino acid substitutions. All four mutations were associated with a unique apo B haplotype, different from those found in Caucasian FDB patients but concurring with that previously reported for two other Asians with FDB.
Adolescent↗
The prevalence of isolated unconjugated hyperbilirubinaemia (Gilbert's syndrome) in subjects attending a health screening programme in Singapore.
We retrospectively studied the prevalence of hyperbilirubinaemia in 1,296 consecutive subjects attending a hospital health screening programme over an eighteen-month period. Sixty-four subjects (5%) had elevated bilirubin levels. Forty-one subjects (3.2%) had isolated unconjugated hyperbilirubinaemia. These subjects probably had Gilbert's syndrome. Recognition of this common benign condition is important to avoid unnecessary investigations.
Adolescent↗
Plasma lipid profiles: the expanding repertoire of tests, their clinical significance and pitfalls.
Hyperlipidaemia and in particular hypercholesterolaemia is the best established cause of atherosclerosis. As awareness of this association grows amongst a more informed populace, there will be an increasing demand for plasma lipid screening. The traditional measurements of total plasma cholesterol and triglycerides for the assessment of hyperlipidaemia and its attendant CHD risk are now augmented by the availability of routine methods for separating and quantitating the different plasma lipoproteins, thus vastly improving diagnostic sensitivity. Because it is the major carrier of cholesterol in plasma and because the mechanistic evidence relating it to atherogenesis is strongest, elevated levels of the low density lipoproteins (LDL) are undesirable: high levels of high density lipoproteins (HDL), on the other hand, decrease the risk. Currently, plasma LDL and HDL concentrations are most frequently assessed by measuring their cholesterol content. However, the measurement of apolipoproteins, the protein components of the lipoproteins, may yet prove to be superior in predictive value, though they can hardly be expected to replace the older tests as first line screening tests by virtue of their relative costs and sophistication in terms of instrumentation and techniques. Additional diagnostic tests have been developed and newer ones will no doubt continue to evolve with further technical advancements and a better understanding of the pathogenesis of atheromas and vessel disease. The current lineup includes HDL subfractions, unique lipoproteins such as Lp(a) and beta-migrating VLDL and apolipoprotein E variants.(ABSTRACT TRUNCATED AT 250 WORDS)
Apolipoproteins↗
Serum fructosamine determination as an index of glycaemic control: comparison between an automated and manual method, and the effect of serum storage.
The measurement of glycated serum proteins was recently introduced as an alternative index of diabetic control of glycated haemoglobin. Manual and automated serum fructosamine colorimetric assays are available for glycated serum proteins determination. We have assessed two serum fructosamine assays, an automated and a manual method, and compared them with a glycated haemoglobin assay. We also studied the effect of serum storage on serum fructosamine concentrations. Serum fructosamine at four different concentrations measured by automated method gave an inner-assay of a 2% (range 1.29 - 1.56%) and an inter-assay variation of 3% (range 1.63-2.92%). There was a good correlation between the automated and manual methods, with a coefficient of r = 0.944. Serum fructosamine by either method is a sample assay to perform and is relatively inexpensive. With automated analysis, a large number of tests can be performed more rapidly. Comparing serum fructosamine with glycated haemoglobin, coefficients = 0.54 (automated) and r = 0.50 (manual) were obtained. An increase in serum fructosamine by 5-20% occurred when the assay is performed on serum samples stored for more than two weeks. It is recommended therefore that test should be performed soon after blood collection, preferably within one week.
Blood Glucose↗
The Bio-Rad Diamat Analyser: an automated liquid chromatography system for haemoglobin A 1c (HbA 1c) determination.
The measurement of glycosylated haemoglobin is a relatively new clinical tool, the assays for their determination having become increasingly available since their introduction in the late seventies. The clinical usefulness of these assays in the long-term monitoring of diabetics, especially the pregnant diabetics, appears to be generally accepted. There remains, however, considerable confusion amongst clinicians as to their reliability and interpretation. This is largely engendered by the diversity of the diagnostic methods in current usage, many of which are not specific for the HbA1c moiety, which is the subfraction comprising haemoglobin molecules with attached glucose molecules at the amino terminal valine sites, and which has been shown to be increased in the blood of diabetic patients. This paper describes an evaluation of one of the most specific methods currently available, using state-of-the-art technology. In addition to specificity, the method appears attractive in being precise, automatable (and thus operator-independent), and rapid.
Adult↗
Altered fibrinolysis in DVT: influence of site of sampling.
Alteration of the fibrinolytic system is considered to be important in the development of deep venous thrombosis (DVT). Using specific assays for tissue plasminogen activator (t-PA) activity, t-PA inhibitor (PAI) and t-PA antigen, we measured these activities in 16 women who developed DVT during their pregnancies. A group of 24 healthy females of comparable age was studied as controls. PAI was increased in 87% of these patients compared to the healthy controls. In some of these patients a defect in release of t-PA from vascular endothelium was found as well. The site at which blood was sampled for analysis appeared to be an important criterion in the ex vivo assessment of functional t-PA reserve and PAI levels, though relatively less so for the latter measurement. The unaffected lower limbs, relative to the unaffected upper limbs, showed an increase in PAI and a demonstrable decrease in t-PA release, both representing increased risk factors for rethrombosis. The affected lower limbs showed similar but more accentuated changes in these parameters.
Adult↗
Fructosamine concentrations in the serum of diabetics and healthy individuals in Singapore.
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Diabetes Mellitus↗
Immunocytochemical localization of prolactin and relaxin C-peptide in human decidua and placenta.
The production of PRL by the human decidua is generally accepted, but the production of relaxin by this tissue is not. The two hormones were localized in decidual tissue using the avidin-biotin immunoperoxidase procedure with antisera to human PRL and to a synthetic 14-amino acid sequence of the connecting peptide of human relaxin (hCp14). The object of using the hCp14 antiserum was to verify relaxin production by the detection of C-peptide and/or prorelaxin. Cells of the parietal decidua adherent to the fetal membranes stained with both antisera, and immunostaining for both hormones in the same cell was seen. Also, the decidua-like cells of the placental basal plate stained with both antisera. The chorionic cytotrophoblast stained with the antiserum to hCp14, but not the antiserum to human PRL, whereas the placental syncytiotrophoblast stained for PRL and/or human placental lactogen (hPL), but not hCp14. The PRL staining in all tissues was lost when anti-PRL serum absorbed with human placental lactogen (hPL) was used. This finding suggests that the antiserum to PRL could not distinguish between PRL and hPL. It appears, therefore, that the parietal decidua cells and the decidua-like cells of the placental basal plate may be capable of producing both relaxin and PRL, while the syncytiotrophoblast produces hPL and possibly PRL.
Decidua↗
Results with a fructosamine kit for a group of diabetics in Southeast Asia.
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Asia, Southeastern↗
The human fetal membranes: a target tissue for relaxin.
The purpose of this study was to adduce further evidence for a paracrine role for human decidual relaxin (Rlx) in the remodelling of collagen in the fetal membranes in the peripartal period. The binding of [125I]porcine Rlx to membrane-enriched fractions from fetal membranes as well as from dispersed cells from the fetal membranes was used to demonstrate the presence of specific Rlx receptors. Rlx added in vitro to cultured amnion/chorion cells increased the release of plasminogen activator and collagenase into the medium. Rlx had no effect on the release of beta-glucuronidase. An in vivo correlate of these in vitro results was obtained, the detection of plasminogen activator and collagenase in amniotic fluids. The active fraction of collagenase was increased in amniotic fluids collected after spontaneous rupture of the membranes. PRL, hCG, estrogen, and progesterone added in equimolar amounts to cultured amnion/chorion cells from elective cesarean sections and normal term deliveries also effected the release of plasminogen activator and collagenase. The greatest effects were found in cells from cesarean section tissue, in terms of the stimulation of plasminogen activator release by Rlx and PRL and of collagenase release by prostaglandin F2 alpha and, to a lesser extent, by Rlx, PRL, and hCG. We conclude that human fetal membranes are targets for a number of hormones, including the decidual paracrine hormones Rlx, PRL, and prostaglandin F2 alpha as well as estrogen, progesterone, and hCG. These hormones act to release or inhibit the enzymes involved in collagen breakdown before rupture of the fetal membranes.
Amnion↗
Immunocytochemical localization of relaxin in human decidua and placenta.
Specimens from 20 human term placentas were stained with 4 different antisera produced against porcine relaxin (Rlx) using the avidin-biotin immunoperoxidase procedure. Cells of the parietal decidua adherent to the fetal membranes, cells of the chorionic cytotrophoblast, as well as cells of the placental basal plate consistently stained with all 4 anti-Rlx sera. Occasionally, Rlx was detected in epithelial cells lining the amniotic membrane. The syncytiotrophoblast stained for Rlx in 2 specimens only. This response was seen only in syncytiotrophoblast that lined villi in close proximity to the basal plate. Syncytiotrophoblast of the chorionic villi either did not stain at all or gave very weak positive immunostaining with the anti-Rlx sera in all specimens. No difference was noted in staining patterns among placentas delivered by elective cesarean section or vaginal delivery.
Chorionic Villi↗
Relaxin stimulates collagenase and plasminogen activator secretion by dispersed human amnion and chorion cells in vitro.
Dispersed cells from human amnion and chorion were cultured with and without relaxin. The addition of this hormone caused an increased secretion of both collagenase and plasminogen activator into the culture medium over a 32 h period, but had no effect on proteoglycanase or beta-glucuronidase secretion. The increase in plasminogen activator was dose-related to the amount of relaxin added in vitro. The results show that the fetal membranes are a novel target tissue for relaxin in the human, and suggest that relaxin in vivo may cause a similar release of collagenolytic enzymes, leading to the weakening and eventual rupture of the fetal membranes.
Amnion↗