Genetic and functional studies of the LMF1 gene in Thai patients with severe hypertriglyceridemia.

Severe hypertriglyceridemia (HTG) due to chylomicronemia is associated with acute pancreatitis and is related to genetic disturbances in several proteins involved in triglyceride (TG) metabolism. Lipase maturation factor 1 (LMF1) is a protein essential for the maturation of lipoprotein lipase (LPL). In this study, we examined the genetic spectrum of the LMF1 gene among subjects with severe HTG and investigated the functional significance of 6 genetic variants in vitro. All 11 exons of the LMF1 gene were sequenced in 101 Thai subjects with severe HTG. For an in vitro study, we performed site-directed mutagenesis, transient expression in cld cells, and measured LPL protein and LPL activity. We identified 2 common variants [p.(Gly36Asp) and p.(Pro562Arg)] and 12 rare variants [p.(Thr143Met), p.(Asn249Ser), p.(Ala287Val), p.(Met346Val), p.(Thr395Ile), p.(Gly410Arg), p.(Asp433Asn), p.(Asp491Asn), p.(Asn501Tyr), p.(Ala504Val), p.(Arg523His), and p.(Leu563Arg)] in 29 patients. In vitro study of the p.(Gly36Asp), p.(Asn249Ser), p.(Ala287Val), p.(Asn501Tyr), p.(Pro562Arg) and p.(Leu563Arg) variants, however, revealed that both LPL mass and LPL activity in each of the transfected cells were not significantly different from those in the wild type LMF1 transfected cells, suggesting that these variants might not play a significant role in severe HTG phenotype in our subjects.

Clinical and functional studies of two novel variants in the LPL gene in subjects with severe hypertriglyceridemia.

BACKGROUND: Two novel variants (p.Arg270Gly and p.Asp308Glyfs*3) in the LPL gene have recently been identified in subjects with hypertriglyceridemia (HTG). In this study, we investigated clinical and genetic features of their families and examined the functional significance of these two variants in vitro. METHODS: Clinical and genetic data were collected. Site-directed mutagenesis and transient expression in cld cells were performed. Lipoprotein lipase (LPL) mass and activity were measured. RESULTS: In vitro studies showed that LPL mass and activity in the media of cells transfected with the p.Arg270Gly variant were significantly reduced. In the cell lysates, however, LPL mass was preserved but LPL activity was reduced, suggesting that the LPL defect was in the secretion and activity. For the p.Asp308Glyfs*3 variant, LPL mass in the cell lysate was relatively preserved compared to that of the wild-type, while LPL mass in the media was decreased albeit not significantly. LPL activities in the cell lysate and in the media of cells transfected with this variant were significantly reduced, suggesting that the p.Asp308Glyfs*3 variant might affect the activity, and possibly, secretion of LPL. CONCLUSIONS: These novel variants in the LPL gene were likely pathogenic with the defect in secretion and/or activity.

Rare and common variants in LPL and APOA5 in Thai subjects with severe hypertriglyceridemia: A resequencing approach.

BACKGROUND: Severe hypertriglyceridemia usually results from a combination of genetic and environmental factors. Few data exist on the genetics of severe hypertriglyceridemia in Asian populations. OBJECTIVE: To examine the genetic variants of 3 candidate genes known to influence triglyceride metabolism, LPL, APOC2, and APOA5, which encode lipoprotein lipase, apolipoprotein C-II, and apolipoprotein A-V, respectively, in a large group of Thai subjects with severe hypertriglyceridemia. METHODS: We identified sequence variants of LPL, APOC2, and APOA5 by sequencing exons and exon-intron junctions in 101 subjects with triglyceride levels ≥ 10 mmol/L (886 mg/dL) and compared with those of 111 normotriglyceridemic subjects. RESULTS: Six different rare variants in LPL were found in 13 patients, 2 of which were novel (1 heterozygous missense variant: p.Arg270Gly and 1 frameshift variant: p.Asp308Glyfs*3). Four previously identified heterozygous missense variants in LPL were p.Ala98Thr, p.Leu279Val, p.Leu279Arg, and p.Arg432Thr. Collectively, these rare variants were found only in the hypertriglyceridemic group but not in the control group (13% vs 0%, P < .0001). One common variant in APOA5 (p.Gly185Cys, rs2075291) was found at a higher frequency in the hypertriglyceridemic group compared with the control group (25% vs 6%, respectively, P < .0005). Altogether, rare variants in LPL or APOA5 and/or the common APOA5 p.Gly185Cys variant were found in 37% of the hypertriglyceridemic group vs 6% in the controls (P = 3.1 × 10(-8)). No rare variant in APOC2 was identified. CONCLUSIONS: Rare variants in LPL and a common variant in APOA5 were more commonly found in Thai subjects with severe hypertriglyceridemia. A common p.Gly185Cys APOA5 variant, in particular, was quite prevalent and potentially contributed to hypertriglyceridemia in this group of patients.

Apolipoprotein A-V is not a major determinant of triglyceride levels during human sepsis.

PURPOSE: During critical illnesses, alterations in lipid metabolism occur. We examined levels of apolipoprotein A-V, a novel regulator of triglyceride metabolism, during sepsis in humans. METHODS: Seventy-five cases of sepsis and 75 cases of acute illnesses not associated with infection were recruited. Lipids and apolipoprotein A-V levels were measured by enzymatic methods and enzyme-linked immunosorbent assay, respectively, within 24 hours of diagnosis. Fifty healthy controls were also enrolled. RESULTS: During sepsis and acute illnesses, serum total cholesterol and high-density lipoprotein cholesterol levels were significantly lower than those in controls. Serum triglyceride levels, however, were not significantly different. Similarly, serum apolipoprotein A-V levels during sepsis were not significantly different from those during acute illnesses and those in controls (expressed as median [interquartile range]: 149.6 [97.5-257.1] vs 157.9 [98.4-238.2] and 155.9 [91.5-253.8] ng/mL, respectively; P = .98); and they were not correlated with serum triglyceride levels. Low apolipoprotein A-V levels were associated with higher mortality, but the association became nonsignificant after adjusting for high-density lipoprotein cholesterol levels. CONCLUSIONS: During sepsis or acute illnesses, serum apolipoprotein A-V levels were not significantly different from those in controls. Furthermore, apolipoprotein A-V levels were not linearly correlated with triglyceride levels, suggesting that it might not be a major determinant of triglyceride levels during sepsis.

Adipocyte ATP-binding cassette G1 promotes triglyceride storage, fat mass growth, and human obesity.

The role of the ATP-binding cassette G1 (ABCG1) transporter in human pathophysiology is still largely unknown. Indeed, beyond its role in mediating free cholesterol efflux to HDL, the ABCG1 transporter equally promotes lipid accumulation in a triglyceride (TG)-rich environment through regulation of the bioavailability of lipoprotein lipase (LPL). Because both ABCG1 and LPL are expressed in adipose tissue, we hypothesized that ABCG1 is implicated in adipocyte TG storage and therefore could be a major actor in adipose tissue fat accumulation. Silencing of Abcg1 expression by RNA interference in 3T3-L1 preadipocytes compromised LPL-dependent TG accumulation during the initial phase of differentiation. Generation of stable Abcg1 knockdown 3T3-L1 adipocytes revealed that Abcg1 deficiency reduces TG storage and diminishes lipid droplet size through inhibition of Pparγ expression. Strikingly, local inhibition of adipocyte Abcg1 in adipose tissue from mice fed a high-fat diet led to a rapid decrease of adiposity and weight gain. Analysis of two frequent ABCG1 single nucleotide polymorphisms (rs1893590 [A/C] and rs1378577 [T/G]) in morbidly obese individuals indicated that elevated ABCG1 expression in adipose tissue was associated with increased PPARγ expression and adiposity concomitant to increased fat mass and BMI (haplotype AT>GC). The critical role of ABCG1 in obesity was further confirmed in independent populations of severe obese and diabetic obese individuals. This study identifies for the first time a major role of adipocyte ABCG1 in adiposity and fat mass growth and suggests that adipose ABCG1 might represent a potential therapeutic target in obesity.

ABCG1 is involved in vitamin E efflux.

Vitamin E membrane transport has been shown to involve the cholesterol transporters SR-BI, ABCA1 and NPC1L1. Our aim was to investigate the possible participation of another cholesterol transporter in cellular vitamin E efflux: ABCG1. In Abcgl-deficient mice, vitamin E concentration was reduced in plasma lipoproteins whereas most tissues displayed a higher vitamin E content compared to wild-type mice. α- and γ-tocopherol efflux was increased in CHO cells overexpressing human ABCG1 compared to control cells. Conversely, α- and γ- tocopherol efflux was decreased in ABCG1-knockdown human cells (Hep3B hepatocytes and THP-1 macro- phages). Interestingly, α- and γ-tocopherol significantly downregulated ABCG1 and ABCA1 expression levels in Hep3B and THP-1, an effect confirmed in vivo in rats given vitamin E for 5 days. This was likely due to reduced LXR activation by oxysterols, as Hep3B cells and rat liver treated with vitamin E displayed a significantly reduced content in oxysterols compared to their respective controls. Overall, the present study reveals for the first time that ABCG1 is involved in cellular vitamin E efflux.

Multimerization of glycosylphosphatidylinositol-anchored high density lipoprotein-binding protein 1 (GPIHBP1) and familial chylomicronemia from a serine-to-cysteine substitution in GPIHBP1 Ly6 domain.

GPIHBP1, a glycosylphosphatidylinositol-anchored glycoprotein of microvascular endothelial cells, binds lipoprotein lipase (LPL) within the interstitial spaces and transports it across endothelial cells to the capillary lumen. The ability of GPIHBP1 to bind LPL depends on the Ly6 domain, a three-fingered structure containing 10 cysteines and a conserved pattern of disulfide bond formation. Here, we report a patient with severe hypertriglyceridemia who was homozygous for a GPIHBP1 point mutation that converted a serine in the GPIHBP1 Ly6 domain (Ser-107) to a cysteine. Two hypertriglyceridemic siblings were homozygous for the same mutation. All three homozygotes had very low levels of LPL in the preheparin plasma. We suspected that the extra cysteine in GPIHBP1-S107C might prevent the trafficking of the protein to the cell surface, but this was not the case. However, nearly all of the GPIHBP1-S107C on the cell surface was in the form of disulfide-linked dimers and multimers, whereas wild-type GPIHBP1 was predominantly monomeric. An insect cell GPIHBP1 expression system confirmed the propensity of GPIHBP1-S107C to form disulfide-linked dimers and to form multimers. Functional studies showed that only GPIHBP1 monomers bind LPL. In keeping with that finding, there was no binding of LPL to GPIHBP1-S107C in either cell-based or cell-free binding assays. We conclude that an extra cysteine in the GPIHBP1 Ly6 motif results in multimerization of GPIHBP1, defective LPL binding, and severe hypertriglyceridemia.

Up-regulation of the ATP-binding cassette transporter A1 inhibits hepatitis C virus infection.

Hepatitis C virus (HCV) establishes infection using host lipid metabolism pathways that are thus considered potential targets for indirect anti-HCV strategies. HCV enters the cell via clathrin-dependent endocytosis, interacting with several receptors, and virus-cell fusion, which depends on acidic pH and the integrity of cholesterol-rich domains of the hepatocyte membrane. The ATP-binding Cassette Transporter A1 (ABCA1) mediates cholesterol efflux from hepatocytes to extracellular Apolipoprotein A1 and moves cholesterol within cell membranes. Furthermore, it generates high-density lipoprotein (HDL) particles. HDL protects against arteriosclerosis and cardiovascular disease. We show that the up-regulation of ABCA1 gene expression and its cholesterol efflux function in Huh7.5 hepatoma cells, using the liver X receptor (LXR) agonist GW3965, impairs HCV infection and decreases levels of virus produced. ABCA1-stimulation inhibited HCV cell entry, acting on virus-host cell fusion, but had no impact on virus attachment, replication, or assembly/secretion. It did not affect infectivity or properties of virus particles produced. Silencing of the ABCA1 gene and reduction of the specific cholesterol efflux function counteracted the inhibitory effect of the GW3965 on HCV infection, providing evidence for a key role of ABCA1 in this process. Impaired virus-cell entry correlated with the reorganisation of cholesterol-rich membrane microdomains (lipid rafts). The inhibitory effect could be reversed by an exogenous cholesterol supply, indicating that restriction of HCV infection was induced by changes of cholesterol content/distribution in membrane regions essential for virus-cell fusion. Stimulation of ABCA1 expression by GW3965 inhibited HCV infection of both human primary hepatocytes and isolated human liver slices. This study reveals that pharmacological stimulation of the ABCA1-dependent cholesterol efflux pathway disrupts membrane cholesterol homeostasis, leading to the inhibition of virus-cell fusion and thus HCV cell entry. Therefore besides other beneficial roles, ABCA1 might represent a potential target for HCV therapy.

Improved plasma cholesterol efflux capacity from human macrophages in patients with hyperalphalipoproteinemia.

OBJECTIVES: CETP or HL deficiencies lead to a marked increase in HDL-C levels however the atheroprotective effect of this phenotype, in particular the ability of HDL particles to remove cholesterol from human macrophages, remains to be determined. METHODS: We measured cholesterol efflux from human THP-1 macrophages to total plasma or to isolated HDL subfractions in patients with HALP carrying molecular defect in either the CETP or LIPC gene. RESULTS: We demonstrate that HALP is associated with an increased plasma cholesterol efflux capacity from human macrophages. This observation is primarily related to a stimulation of both SR-BI and ABCA1 dependent efflux pathways as a result of quantitative elevation in HDL2 and enhanced intrinsic capacity of HDL3 subspecies, respectively. CONCLUSION: HDL particles from HALP patients with molecular defect within either CETP or LIPC gene are not dysfunctional and are efficient to stimulate cholesterol efflux from human macrophages.

Functional characterization of novel variants in the CETP promoter and the LIPC gene in subjects with hyperalphalipoproteinemia.

BACKGROUND: Variants in the CETP and the LIPC genes, encoding cholesteryl ester transfer protein and hepatic lipase, respectively, are associated with high levels of HDL-cholesterol or hyperalphalipoproteinemia (HALP). Recently, we have identified three novel variants in the CETP promoter and two novel variants in LIPC in Thai subjects with HALP. In this study, we investigated the functions of these 5 variants in vitro. METHODS: For CETP promoter variants, we used site-directed mutagenesis, transient expression in HepG2 cells and luciferase reporter assay. For LIPC variants, cDNA was cloned and mutagenesis for missense variants was performed before expression in HepG2 cells. RESULTS: The transcriptional activities of -49G>T,-70C>T, and -372C>T CETP promoter variants were markedly reduced (5%, 8% and 30%, respectively, compared to that of the wild-type, P<0.001). For LIPC variants, hepatic lipase activities in the lysates of cells transfected with c.421A>G (p.G141S) and c.517G>A (p.V173M) variants were 41% and 46%, respectively, compared to that of the wild-type (P<0.05). CONCLUSIONS: The recently-identified variants in the CETP promoter and in the LIPC gene may contribute to HALP. Our result may have a diagnostic application in the genetic evaluation of subjects with high HDL-cholesterol levels.

Resequencing CETP, LIPC and LIPG genes in Thai subjects with hyperalphalipoproteinemia.

Genetic factors associated with hyperalphalipoproteinemia (HALP; or high levels of high-density lipoprotein cholesterol) are incompletely understood. The aim of this study was to resequence 3 candidate genes, CETP, LIPC, and LIPG, which encode cholesteryl ester transfer protein, hepatic lipase, and endothelial lipase, respectively, in Thai subjects with HALP and compare them to normolipidemic controls. Sequence variants of CETP, LIPC, and LIPG were identified by sequencing exons and exon-intron junctions in 64 subjects with high-density lipoprotein cholesterol levels ≥2.59 mmol/L (100 mg/dl) and compared to those of 113 normolipidemic subjects. Two heterozygous frameshift mutations in CETP (p.Leu262ProfsX31 and p.Val411ArgfsX6) and two heterozygous missense mutations in LIPC (p.Gly141Ser and p.Val173Met) were found. One deletion mutation and 3 point mutations in the CETP promoter were also identified. Collectively, these rare mutations were found only in the HALP group but not in the control group (8% vs 0%, p = 0.0056). One common variant of CETP (p.Asp459Gly) was found at a higher frequency in the HALP group (23% vs 4%, p = 0.000074). Altogether, rare variants of CETP or LIPC and/or the common CETP p.Asp459Gly variant were found in 30% of the HALP group and 4% of the controls (p = 0.0000014). No rare variant of LIPG was identified. In conclusion, common and rare genetic variants in CETP and LIPC, but not LIPG, were more commonly found in the Thai HALP group, which could potentially contribute to high high-density lipoprotein cholesterol phenotypes in this population.

Retinol-binding protein 4 is not associated with insulin resistance in pregnancy.

Retinol-binding protein 4 (RBP4) is an adipokine proposed to be specifically associated with insulin resistance (IR). We examined whether serum levels of RBP4 were associated with IR in pregnancy. One hundred seventy-two women with gestational diabetes mellitus (GDM) and 361 pregnant Thai women who did not have GDM but had a positive 50-g glucose challenge test result (plasma glucose level was ≥7.2 mmol/L after 1 hour) were enrolled. We measured fasting serum levels of RBP4 and assessed IR at a 100-g oral glucose tolerance test. We found a higher degree of IR in the GDM group compared with the non-GDM group, but serum RBP4 levels between the 2 groups were not different. Retinol-binding protein 4 levels were associated with serum triglyceride levels but were not associated with the degree of IR assessed by homeostasis model assessment or quantitative insulin sensitivity check index. Our results suggest that serum RBP4 levels in pregnancy are not associated with IR.

CETP deficiency due to a novel mutation in the CETP gene promoter and its effect on cholesterol efflux and selective uptake into hepatocytes.

OBJECTIVES: To identify the genetic variant in the CETP gene of the proband with high HDL-C and low CETP activity and to investigate whether HDL from the CETP-deficient subject was dysfunctional in the reverse cholesterol transport (RCT) pathway. METHODS: We sequenced the CETP gene and assessed its promoter activity. Cholesterol efflux and hepatic cholesteryl ester delivery studies were also performed using the proband's HDL. RESULTS: A proband was a compound heterozygote for a known D459G variant and a novel 18-bp deletion mutation in the CETP promoter. This promoter mutation markedly reduced the transcriptional activity in HepG2 cells. HDL2 from this subject increased SR-BI-mediated cholesterol efflux, whereas cholesteryl ester delivery into hepatocytes was maintained. CONCLUSION: A novel deletion mutation in the CETP promoter is associated with high HDL-C and decreased promoter activity. HDL from this CETP-deficient subject was not dysfunctional in mediating two main steps of RCT assessed in vitro.

Concurrent bilateral pheochromocytoma and thoracic paraganglioma during pregnancy.

Although hypertension occurring during pregnancies is not uncommon and its prognosis is generally excellent, some of its unusual causes can lead to catastrophic consequences, especially in undiagnosed cases. Here, we report a pregnant woman who presented with hypertension in her early pregnancy. It was subsequently found to be caused by bilateral pheochromocytoma. After removal of both tumors, catecholamine levels unexpectedly and unexplainably remained elevated. At 23 weeks of gestation, the fetus was found dead in utero. After the fetal death, additional studies were performed and revealed a thoracic paraganglioma. To our knowledge, this is the first report of a case of three catecholamine-producing tumors occurring concurrently during a pregnancy. Genetic analysis helped identify this unprecedented condition; the patient harbored a heterozygous missense mutation c.482G>A in exon 3 of the VHL gene, indicating von Hippel-Lindau syndrome. Physicians who care for hypertensive pregnant patients should be aware of this condition as its diagnosis would probably lead to a better outcome.

Two novel mutations and functional analyses of the CETP and LIPC genes underlying severe hyperalphalipoproteinemia.

Previous studies have shown that CETP and LIPC mutations contribute to hyperalphalipoproteinemia (HALP) in some populations. We investigated whether activities in cholesteryl ester transfer protein (CETP) and hepatic lipase (HL) contribute to HALP in the Thai population and performed genetic analyses of the CETP and LIPC genes. We recruited 38 individuals with high-density lipoprotein cholesterol (HDL-C) levels of at least 2.59 mmol/L (100 mg/dL) (HALP group) and an equal number of individuals with normal serum HDL-C levels (control group). The CETP and HL activities were determined in both groups. Genetic analyses covering all the coding regions and exon-intron junctions of the CETP and LIPC genes were performed in subjects who had low CETP activity and HL activity, respectively. The mean CETP and HL activities were significantly lower in the HALP group than in the control group (34 +/- 4 vs 44 +/- 3 pmol/[microL h], P = .04 and 150 +/- 17 vs 227 +/- 16 nmol free fatty acid/[mL min] P = .002, respectively). Of the 38 individuals with HALP, 19 and 16 were found to have low CETP activity and HL activity, respectively. Of the 19 subjects with low CETP activity, 6 subjects were found to be heterozygous for a known functionally relevant c.1325A>G (D442G) mutation. The other subject was found to be heterozygous for a novel deletion mutation, c.734_737delTCCC mutation. Of the 16 subjects with low HL activity, 8 and 2 subjects were found to be heterozygous for known variants, c.283 G>A (V73M) and c.1068A>C (L334F), respectively. These variants have previously been shown not to be associated with HALP. Another subject was found to be heterozygous for a novel missense mutation, c.421G>A (G119S). Its amino acid change, absence in controls, evolutionary conservation, occurrence in functionally important domain, and predicted damaging function suggested that the G119S mutation is functionally relevant. Two novel mutations in the CETP and LIPC genes found in this study are likely to be the causes of low enzyme activities and elevated HDL-C levels.

Bilateral pheochromocytoma during the postpartum period.

BACKGROUND: Pheochromocytoma manifesting during pregnancy is uncommon but it is responsible for a high maternal and fetal mortality rate, especially when unrecognized. Most cases of pheochromocytoma are sporadic but they can be part of hereditary autosomal dominant syndromes. CASE: We describe a case of bilateral pheochromocytoma in a term-pregnant patient with a previous history of medullary thyroid carcinoma (MTC). Her genetic study revealed a heterozygous mutation, c.1900T>C, in the RET proto-oncogene which confirmed the diagnosis of multiple endocrine neoplasia type 2A (MEN2A). Unrecognized, the tumors caused a crisis with fatal outcome in the mother during the postpartum period. This event might have been prevented if the tumor had been detected previously. CONCLUSION: MEN2A affected pregnancy is an unusual condition. This syndrome should be suspected when a pregnant patient has a history of MTC. Early detection and appropriate management can prevent serious maternal and fetal complications. We also reviewed the literature of MEN2A-affected pregnancies.

A novel SPINK1 gene mutation, c.206C>T, in a Thai patient with chronic alcoholic pancreatitis.

CONTEXT: The exact mechanism of alcoholic pancreatitis has not yet been clarified. Recent studies suggest that alcohol represents only a risk factor for developing pancreatic inflammation in genetic or environmental susceptible subjects. In this regard, various genes involving an alcohol-metabolizing pathway or pancreatitis protecting factors have been extensively studied in order to identify genetic predisposition to alcoholic pancreatitis. CASE REPORT: A 43-year-old man with a history of heavy alcohol drinking presented with recurrent abdominal pain. Alcoholic pancreatitis was diagnosed and responded well to pancreatic stricture dilatation with stent insertion. Sequencing analysis revealed that he was heterozygous for a novel transition c.206C>T in exon 4 of the SPINK1 gene, resulting in the substitution of threonine for isoleucine at codon 69 (T69I). Evidence supporting its etiologic role includes the alteration of the polarity of the amino acid change, its revolutionary conservation among mammals and its absence in 100 ethnic-matched control alleles. CONCLUSIONS: We identified a novel SPINK1 mutation, c.206C>T (T69I), in a Thai patient with alcoholic pancreatitis. This extends the total number of confirmed SPINK1 mutations and polymorphisms to more than 30. It also supports a previous observation that the SPINK1 gene is a susceptibility locus for alcoholic pancreatitis.

Normal reference range of serum insulin-like growth factor (IGF)-I in healthy Thai adults.

BACKGROUND: Serum insulin-like growth factor (IGF)-I level is growth hormone (GH) dependent and reflects GH secretion. Analysis of IGF-I is a component in the diagnosis of GH-related disorders and is going to be of interest in determining the risk of many disorders such as cancer or atherosclerosis. The diagnosis value of IGF-I is dependent on the establishment of an accurate reference ranges, which can be affected by parameters such as age, gender, ethnicity, medications, chronic illness, or assay methodologies. OBJECTIVE: To determine reference ranges of IGF-I for healthy Thai adults. MATERIAL AND METHOD: Eight hundred sixteen healthy Thai adults aged between 21-70 years were recruited in the present study. Serum IGF-I was measured by using immunochemiluminescent (ICMA; Roche, USA). Subjects were recorded by their age and gender groups. Data were presented in mean and +/- 2 standard deviation (SD). Correlation analysis between serum IGF-I and physical parameters including sex, age, weight, height, and body mass index (BMI) was also made. RESULTS: The present study demonstrated normal reference range of serum IGF-I by using mean +/- 2 SD value. The well-known age dependency of serum IGF-I levels was also revealed. Levels decreased with increasing age in both genders. The mean value of serum IGF-I was slightly higher in women at the age of 30-40 years compared with men in the same age group, but not statistically insignificant. In addition, serum IGF-I was found to correlate directly with the height and negatively with BMI. However, age-adjusted IGF-I level did not show correlation with these physical parameters. CONCLUSION: This reference range will be beneficial for using IGF-I assay as a tool in the diagnosis of GH function abnormalities in Thai subjects.

A novel germline mutation, IVS4+1G>A, of the POU1F1 gene underlying combined pituitary hormone deficiency.

BACKGROUND: POU1F1 is a pituitary transcription factor that plays a pivotal role in pituitary development and expression of the GH, PRL and TSH beta genes. Therefore, abnormalities of the POU1F1 gene are known to be responsible for a phenotype causing combined pituitary hormone deficiency (CPHD) involving growth hormone, prolactin and thyrotropin. METHODS: We described an 18-year-old Thai man, from a consanguineous family, who presented with short stature and cognitive deficit. He underwent endocrinological and molecular investigations. RESULTS: Hormonal studies showed that the patient had GH deficiency and secondary hypothyroidism, consistent with CPHD. Direct DNA sequencing revealed a novel homozygous mutation at the splice site of exon 4, IVS4+1G>A. It is the first splice site mutation in the POU1F1 gene described to date. Of the 7 other family members studied for this mutation by restriction enzyme digestions, 5 were heterozygous. They were all unaffected, suggesting a recessive pattern of inheritance. CONCLUSIONS: We described a novel POU1F1 splice site mutation, IVS4+1G>A, the first of its kind, in a Thai patient with CPHD. Recessive inheritance is suggested. We also noted preventable morbidities which resulted from delay in diagnosis of concomitant pituitary hormone defects in newborns suspected of CPHD.

Effects of human apolipoprotein A-I on endotoxin-induced leukocyte adhesion on endothelial cells in vivo and on the growth of Escherichia coli in vitro.

BACKGROUND: High-density lipoprotein (HDL) has been shown to inhibit leukocyte adhesion to endothelial cells induced by endotoxin in vivo and suppress the growth of bacteria in vitro; however, the components responsible for these effects, either lipids or proteins, are not yet defined. In this study, we examined the effects of apolipoprotein (apo) A-I, the major protein of HDL, on ameliorating the effect of endotoxin and inhibiting the growth of bacteria. MATERIALS AND METHODS: Apo A-I, purified from normal human HDL, was incubated with endotoxin. Leukocyte adhesion to endothelial cells of rat mesenteric venules was assessed using intravital fluorescence microscopy. Ability of apo A-I to inhibit the growth of Escherichia coli was assessed using a spread plate method. RESULTS: Purified, lipid-free apo A-I could inhibit endotoxin-induced leukocyte adhesion to endothelial cells in vivo in a dose-dependent manner. In addition, apoA-I was able to suppress the growth of Escherichia coli in vitro. CONCLUSIONS: These data suggest that apo A-I of HDL can directly interact with endotoxin, ameliorating its effect and that apo A-I may have a direct toxic effect on whole bacteria. Therefore, therapeutic use of apo A-I in septicemia and bacterial infection should be further explored.