A magnetic resonance imaging study of iron overload in hemopoietic stem cell transplant recipients with increased ferritin levels

We performed a study of magnetic resonance imaging (MRI) assessment of hemosiderosis in the heart (T2/T2*), liver (T2*), pancreas (T2*), and pituitary gland (T2/T2*/SIR) in 20 hemopoietic stem cell transplant (HSCT) recipients (median peak ferritin levels 7615 pmol/L, range 3411 to 33000 pmol/L). MRI reading was abnormal in the heart (5%), liver (85%), pancreas (40%), and pituitary gland (55%). The heart T2 correlated with peak ferritin levels (P=.024), while the liver T2* correlated with current ferritin (P=.038) values only. Pancreatic T2* values correlated with pituitary T2 and signal intensity ratio values. The ejection fraction was abnormal in 10% of cases and did not correlate with ferritin level or heart T2. The peak liver enzymes correlated with peak ferritin (P=.025), but the current liver enzymes were mostly normal. Pancreatic assessments (fasting glucose, insulin, beta cell function, insulin reserve, and C-peptide) and pituitary growth hormone axis assessments (growth hormone, insulin growth factor-1, and insulin growth factor binding protein-3) were abnormal in 40% to 70% of cases. They were unrelated to pancreas or pituitary MRI values. Interestingly, endocrine assessments correlated with heart T2 values and peak (but not current) ferritin levels. We concluded that iron overload may contribute to organ damage after HSCT, and MRI assessment may be useful in its detection and treatment monitoring.

Complete recovery from acute encephalopathy of late-onset ornithine transcarbamylase deficiency in a 3-year-old boy

Ornithine transcarbamylase deficiency is the commonest urea cycle disorder which is transmitted in X-linked inheritance. It is mainly characterized in males by acute encephalopathy and hyperammonaemia with fatal outcomes in both classical neonatal and late-onset types. We report a 3-year-old healthy Hong Kong Chinese boy who presented with acute encephalopathy and coma after three days of gastroenteritis. He had no focal neurological deficit and brain CT imaging was normal. His plasma ammonia (54 micromol/L) and glutamine (747 micromol/L) concentrations were normal. The only biochemical abnormalities detected were marked orotic aciduria (700 micromol/mmol creatinine) and elevated urinary uracil. He regained consciousness spontaneously after three days under intensive care with parenteral fluid therapy. He recovered completely without any neurological deficits. Five months after discharge, urinary uracil concentration remained elevated despite normalized orotic acid concentration. Finally, ornithine transcarbamylase deficiency was diagnosed by DNA analysis. A missense mutation of arginine-to-glutamine substitution on amino acid 277 (p.R277Q) was revealed to be a late-onset mutant. Our case strengthens the argument that in any child with coma or acute encephalopathy of undetermined cause, genetic analysis of the OTC gene and the measurement of urinary uracil concentration remain the most reliable indicators of late-onset OTCD during acute and even quiescent phases. Existing neonatal screening programmes for inheritable metabolic disorders fail to detect late-onset variants. Therefore, a high clinical suspicion is a key to correct and timely diagnosis, especially in those patients with atypical presentations.

Generation and characterization of sodium-dicarboxylate cotransporter-deficient mice

The sodium-dependent dicarboxylate cotransporter (NaDC1) has a proposed function of reabsorbing various Krebs cycle intermediates in the kidney and the small intestine. Since Krebs cycle intermediates have been suggested to be important for renal cell survival and recovery after hypoxia and reoxygenation, the transporter may play a role in the recovery of the kidney. Additionally, mutations in the transporter homolog in Drosophila led to fly longevity which was thought to be similar to that induced by caloric restriction (CR). To clarify the role of the sodium dicarboxylate cotransporter in vivo we generated cotransporter-deficient mice. These knockout mice excreted significantly higher amounts of various Krebs cycle intermediates in their urine; thus confirming the proposed function to reabsorb these metabolic intermediates in the kidney. No other phenotypic change was identified in these mice, however. Transporter deficiency did not affect renal function under normal physiological conditions, nor did it have an effect on renal damage and recovery from ischemic injury. Additionally, the absence of the transporter did not lead to metabolic or physiological changes associated with CR. Our results suggest that although the sodium dicarboxylate cotransporter is involved in regulating levels of various Krebs cycle intermediates in the kidney, impaired uptake of these intermediates does not significantly affect renal function under normal or ischemic stress.

Burden of carotid atherosclerosis in patients with stroke: relationships with circulating endothelial progenitor cells and hypertension

Recent studies suggest that reductions in circulating endothelial progenitor cells (EPCs) may contribute to the development of atherosclerosis. However, whether reduced circulating EPCs contribute to cerebrovascular disease remains undefined. We tested the hypothesis that reduced circulating EPCs was associated with an increased burden of carotid atherosclerosis. The level of circulating CD34+/KDR+ EPCs and the extent of carotid atherosclerosis were determined in 30 patients with a history of atherothrombotic ischaemic stroke and 30 age- and sex-matched controls (mean age: 63+/-2 years; 63% men). Stroke patients, compared with controls, had significantly higher carotid mean maximum intima-media thickness (mmIMT) (1.08+/-0.05 versus 0.90+/-0.02 mm, P=0.002), prevalence of carotid plaque (60.0 versus 23.3%, P=0.004) and a lower number of circulating CD34+/KDR+ EPCs (235.7+/-45.5 versus 400.4+/-56.8 cells/mul, P=0.027). The circulating CD34+/KDR+ EPC count correlated negatively with carotid mmIMT (r=-0.50, P<0.001), and was an independent risk factor for increased carotid mmIMT>1 mm (odds ratio (OR): 7.71; 95% confidence interval (CI): 1.62-36.74, P=0.010) and the presence of carotid plaque (OR: 7.04; 95% CI: 1.95-25.43, P=0.003). Furthermore, stroke patients with low (<25th percentile of controls) as compared to those with normal CD34+/KDR+ EPC count had a significantly greater carotid mmIMT (1.21+/-0.07 versus 0.93+/-0.05 mm, P=0.005) and a significantly higher prevalence of carotid plaque (87.5% versus 28.6%; P=0.001). Our observations suggested that reduced circulating EPC may contribute to the progression of carotid atherosclerosis. Circulating EPC count may provide a novel marker for the burden of carotid atherosclerosis.

Prevalence and Impact of Vitamin D Insufficiency in Southern Chinese Adults

INTRODUCTION

Vitamin D is a vital element for bone health but the problem of vitamin D deficiency is underestimated in Hong Kong.

METHODS

Serum 25(OH)D and parathyroid hormone (PTH) levels were evaluated in 382 community dwelling Chinese adults >50 years for their relation with bone mineral density (BMD) and risks of osteoporotic fractures and falls.

RESULTS

The mean age of the subjects was 69 +/- 9 years. The mean 25(OH)D level was 28.3 +/- 10.8 ng/ml with 62.8% of the subjects having levels <30 ng/ml. 6.3% of the subjects had elevated PTH levels. A curvilinear relation between serum PTH and 25(OH)D was found, with PTH starting to increase when 25(OH)D level fell below 30 ng/ml (r = -0.233, p < 0.05). Although subjects with vitamin D <30 ng/ml had significantly lower BMD, only sex, age and PTH but not 25(OH)D were predictors of BMD at the spine and hip. Subjects with elevated PTH levels had a 2.92-fold increased risk of falls and 2.94-fold increased risk of fractures at the hip and spine.

CONCLUSIONS

Vitamin D insufficiency and its complication of secondary hyperparathyroidism is common even in subtropical region and is an important risk factor for low bone mass, falls and fractures.

Traditional Chinese medicine causing hepatotoxicity in patients with chronic hepatitis B infection: a 1-year prospective study

BACKGROUND

Safety of traditional Chinese medicine in patients with chronic hepatitis B is unknown.

AIM

To study the clinical outcome of traditional Chinese medicine-induced hepatotoxicity in chronic hepatitis B patients.

PATIENTS AND METHODS

All chronic hepatitis B patients in 2004 with liver dysfunction requiring hospitalization were screened prospectively for traditional Chinese medicine intake. The hepatotoxicity of individual traditional Chinese medicine elements was determined by extensive search of both English and Chinese publications.

RESULTS

Of 45 chronic hepatitis B patients, the liver dysfunction in seven (15.6%) was attributable to traditional Chinese medicine. All had liver dysfunction pattern resembling those of acute exacerbation of chronic hepatitis B. Three patients had adverse outcomes (two deaths, one liver transplantation). One patient had accelerated course of cirrhosis now awaiting liver transplantation. The identified hepatotoxic components were Polygonum multiflorum Thunb, Cassia obtusifolia L, Melia toosendan Sieb., Rheum palmatum L., Scolopendra subspinipes mutilans L, Alisma orientale Juzepe, Glycyrrhiza uralensis Fisch. and Mentha haplocalyx Briq. One traditional Chinese medicine formula was adulterated with a highly hepatotoxic agent, N-nitrosofenfluramine.

CONCLUSIONS

Traditional Chinese medicine-related hepatotoxicity resulted in high mortality in chronic hepatitis B patients. Prospective randomized-controlled trials with the same stringent criteria as western medicine clinical trials are required for Chinese medicines, to document their efficacies and safety before they can be advocated for the treatment of patients.

Plasma apolipoprotein E concentration is an important determinant of phospholipid transfer protein activity in type 2 diabetes mellitus

BACKGROUND

Phospholipid transfer protein (PLTP) transfers phospholipids between lipoproteins and plays an important role in HDL metabolism. PLTP exists as a high-activity and a low-activity form in the circulation. In vitro studies have shown that apolipoprotein (apo) E is involved in maintaining PLTP in the active form, while the low-activity form is associated with apo AI. We have therefore investigated whether plasma apo AI, B and E concentrations are important determinants of plasma PLTP activity in type 2 diabetes, a condition associated with increased plasma PLTP activity.

METHODS

Plasma PLTP activity was assayed by measuring the transfer of radiolabelled phosphatidylcholine from liposomes to HDL; apo AI and B by rate nephelometry and apo E by a 2-point turbidimetric assay.

RESULTS

Type 2 diabetic patients (n = 230) had higher PLTP activity than controls (n = 97) (2374 +/- 628 nmol/mL/h versus 1862 +/- 585 respectively, p < 0.01). They also had increased fasting triglyceride and low HDL. Plasma apo B (p < 0.01) and apo E (p < 0.05) were increased, whereas apo AI was reduced (p < 0.01). Univariate analysis showed that plasma PLTP activity correlated mainly with apolipoproteins AI and E. Stepwise regression analysis showed that apo E was the main determinant of plasma PLTP activity, accounting for 23% of its variability in the diabetic subjects and 8% in the controls respectively.

CONCLUSIONS

The associations between plasma apo AI and E concentrations and PLTP activity suggest that these apolipoproteins are important regulators of PLTP activity in vivo. The increase in PLTP activity in type 2 diabetes is partly related to the changes in these apolipoproteins.

Multivariate analysis of expression of the microtubule-associated protein, tau, predicts improved progression free and overall survival in patients with metastatic HER-2-negative breast cancers treated with docetaxel and vinorelbine plus filgrastim

543

Background: Drugs that poison the mitotic spindle, including taxanes and vinca alkaloids, are active agents against breast cancer. Preliminary evidence showed that high expression levels of tau predicted improved PFS and OS in patients with metastatic HER-2-negative breast cancers treated with docetaxel and vinorelbine plus filgrastim. We now tested whether levels of tau and another microtubule associated protein, beta-tubulin, could predict PFS and OS in multivariate analysis using other prognostic marker studies, including ER, PR, p53 and Ki-67 on a tissue microarray (TMA) obtained from patients in the SWOG S0102 trial. Materials and Methods: Immunohistochemistry (IHC) using antibodies to tau, beta-tubulin, ER, PR, p53, and Ki-67 was performed on a TMA constructed from the S0102 paraffin blocks. All markers were scored semiquantitatively from 0 to 3. Progression free survival (PFS) and overall survival (OS) were evaluated using multivariate analysis. Results: A total of 38 patients (41.3%) were evaluated. Tau was positively correlated with ER (r=0.36; p=0.0325) and PR (r=0.63; p<0.0001), but not with beta tubulin (p=0.34), Ki-67 (p=0.58), or age (p=0.73). Beta tubulin was not significantly correlated with any other markers. Adjusting for age, there was a significant effect of tau expression on OS (HR=0.667, p= 0.0193) and PFS (HR=0.653; p=0.0035), with higher tau associated with longer survival. When adjusted for both age and PR, there was a marginally significant effect of tau on OS (HR=0.582; p=0.056) and PFS (HR=0.604; p= 0.065). Beta tubulin was not associated with OS (HR=0.909; p=0.66) and PFS (HR=0.904; p=0.58) adjusted for age. Conclusions: In multivariate analysis, identification of breast cancer specimens showing high expression levels of tau predicts improved PFS and OS in patients with metastatic HER-2-negative breast cancers treated with docetaxel and vinorelbine plus filgrastim. High expression of tau also correlated with PR and ER expression. These results confirm and expand earlier studies of the predictive power of tau in a multivariate analysis using a panel of IHC markers for breast cancer.

No significant financial relationships to disclose.

Wilson's disease: a patient undiagnosed for 18 years

Wilson's disease, an autosomal recessive disorder of copper metabolism, is the most common inherited hepatic disease in Hong Kong. Diagnosis is based on the presence of Kayser-Fleischer rings, typical neurological symptoms, and/or a low serum ceruloplasmin concentration (<0.20 g/L). Early detection and treatment protect patients and their presymptomatic siblings from devastating organ damage. The diagnosis of Wilson's disease may nonetheless be overlooked if only established clinical and laboratory tests are used as diagnostic criteria. We report diagnosis of the disorder using genetic analysis of ATP7B in a presymptomatic sibling who escaped diagnosis during family screening 18 years previously. The patient was 11 months old when family screening was performed following diagnosis of Wilson's disease in an elder sister. The boy was considered to be unaffected on the basis of laboratory results in the expected range: serum copper level, 4.6 micromol/L; serum ceruloplasmin level, 0.16 g/L; and 24-hour urinary copper excretion, 0.14 micromol/day. Molecular analysis of ATP7B was performed; it revealed that the two siblings shared the same compound heterozygous mutations (G943D and 2299delC). We recommend that molecular diagnosis is the only definitive means of diagnosing Wilson's disease in children younger than 1 year.

Heterogeneous mutations in the SLC3A1 and SLC7A9 genes in Chinese patients with cystinuria

Cystinuria is a recessively inherited aminoaciduria that leads to recurrent urolithiasis. It is caused by the defective transport of cystine and dibasic amino acids in the proximal renal tubules and intestinal epithelium. Two genes responsible for this, SLC3A1 and SLC7A9, are known. Patients with two SLC3A1 mutations are classified as type A cystinuria, whereas patients with two SLC7A9 mutations are classified as type B cystinuria. Few clinical and molecular data have been reported for Asian cystinuria patients. In this study, we determined the molecular basis of cystinuria in eight unrelated Chinese subjects. Coding exons and flanking introns of the SLC3A1 and SLC7A9 genes were directly sequenced after amplification by polymerase chain reaction. Five different SLC3A1 mutations were found. Two missense mutations, D210G and S547L, were novel. The other three SLC3A1 mutations (IVS6+2T>C, R181Q and R365W) have been described previously. In addition, four novel SLC7A9 mutations, C137R, c.730delG, IVS10+2_3delTG and IVS12+3insT, together with two previously reported mutations (A70V and G195R) were found. All patients except one carried compound heterozygous mutations. IVS12+3insT was detected in patients from two families. This is the first molecular genetic study on Chinese cystinuria patients. Three patients with type A cystinuria, two with type B cystinuria, and three carriers of type B cystinuria were identified. Our results suggest that the molecular basis of cystinuria is heterogeneous in our local population.

Determinants of bone mineral density in Chinese men

Osteoporotic fractures are increasing among Asian populations in both genders, but the risk factors for low bone mineral density (BMD) in Asian men is unclear. To determine the hormonal and lifestyle risk factors for low BMD in Asian men, we studied 407 community-dwelling southern Chinese men aged 50 years and above. Medical history and lifestyle habits were obtained with a structured questionnaire. Dietary calcium and phytoestrogen intake were assessed by a semi-quantitative questionnaire. BMD at the spine and hip were measured by dual-energy X-ray absorptiometry (DXA). Fasting blood was analyzed for 25(OH)D, parathyroid hormone (PTH), total and bioavailable estradiol (bio-E) and testosterone (bio-T). The mean age of the cohort was 68.42+/-10.4 (50-96) years. In the linear regression model, weight, age, body mass index (BMI), bio-E, PTH, cigarette smoking and weight-bearing exercise were significant determinants of total hip BMD. Together they explained 55% of the total variance of hip BMD, with body weight being the most important determining factor. With age and weight adjustment, height, bio-T and flavonoid intake were identified as additional determinants of total hip BMD. Strategies to prevent bone loss and osteoporosis in Asian men should include lifestyle modification and maintenance of hormonal sufficiency.

A pilot study of participation in faecal occult blood testing and screening colonoscopy after health education in Hong Kong

Colorectal cancer is the second commonest cancer in Hong Kong. The screening behaviour of the Chinese population has not been assessed. The aim of this study is to report a pilot study of educating and subsequent evaluation of colorectal cancer screening behaviour in the Hong Kong Chinese population. Subjects were invited to attend a free health talk on colorectal cancer. Both self-paid faecal occult blood testing (FOBT) and free screening colonoscopy were offered after the education programme. Of the participants taking part in the education programme 113/119 (95%) completed the FOBT. Of the FOBT 8/113 (7%) showed positive result and three patients had neoplasia at colonoscopy. Twenty-five patients with negative FOBT also completed colonoscopy; two had adenomas. Screening colonoscopy after FOBT was accepted by 28% of subjects. Those younger than 65 years and those with a positive FOBT (7/8 versus 25/105 for those with negative FOBT, P=0.0003) were more likely to agree to screening colonoscopy. In conclusion, health education is important for ensuring high acceptance and implementation of colorectal cancer screening in Hong Kong Chinese. FOBT is an acceptable and feasible screening method in Hong Kong.

Determinants of postprandial triglyceride and remnant-like lipoproteins in type 2 diabetes

BACKGROUND

Postprandial changes in remnant-like lipoprotein particles (RLP) contribute to the severity of coronary heart disease in type 2 diabetes. Since the determinants of postprandial response in RLP are not well understood, this study investigated the roles of fasting triglyceride, apolipoprotein (apo) E polymorphism and insulin resistance in a group of overweight/obese Chinese type 2 diabetic subjects.

METHODS

Postprandial triglyceride (TG) and RLP-cholesterol (RLP-C) were determined after a mixed meal containing 70-g fat at 2-h intervals for 8 h in 32 normotriglyceridemic (NTG) and 31 hypertriglyceridemic (HTG) subjects. RLP-C was measured using an immunoseparation assay and apo E genotypes using polymerase chain reaction and restriction mapping. Insulin resistance was defined as homeostasis model assessment index (HOMA-IR).

RESULTS

The HTG subjects had greater postprandial increase in TG and RLP-C than NTG (p < 0.001), but there were no significant differences in HOMA-IR and apo E allele frequencies. Subjects who were non-E3-carriers had the largest postprandial increment in TG and RLP-C. On stepwise linear regression analysis, log(HOMA-IR) was only an independent determinant of fasting TG but not postprandial TG or RLP-C. The major determinants of fasting and postprandial RLP-C were fasting TG and apo E genotype, accounting for 53 and 6% of the variance of fasting RLP-C (p < 0.01) and 31 and 13% of the variance of postprandial RLP-C respectively (p < 0.01).

CONCLUSIONS

Insulin resistance is mainly a determinant of fasting triglyceride in Chinese type 2 diabetic subjects, whereas apo E genotype is a better predictor of both fasting and postprandial concentrations of RLP.

Plasma phospholipid transfer protein activity and subclinical inflammation in type 2 diabetes mellitus

Phospholipid transfer protein (PLTP) transfers phospholipids between lipoproteins, and plays an essential role in HDL metabolism. The regulation of PLTP is poorly understood and recent evidence suggests that PLTP activity increases during acute-phase response. Since type 2 diabetes is associated with chronic subclinical inflammation, the objective is to determine whether inflammation modulates PLTP in diabetes. Plasma PLTP activity was assayed by measuring the transfer of radiolabeled phosphatidylcholine from liposomes to HDL and high-sensitivity C-reactive protein (CRP) by immunoturbidimetric assay in 280 type 2 diabetic patients and 105 controls. Plasma PLTP activity (2364+/-651 nmol/ml/h versus 1880+/-586 nmol/ml/h in control, mean +/- S.D., P <0.01) and CRP (1.64(0.89-3.23)mg/l versus 0.99(0.53-2.23 mg/l, median (interquartile range), P<0.01) were increased in diabetic subjects. PLTP activity correlated significantly with age, BMI, HbA1c, log(CRP) and apolipoprotein AI and B in diabetic subjects. General linear model analysis showed that only apolipoprotein AI, age, BMI, and log(CRP) were independent determinants of PLTP activity. In conclusion, PLTP activity is increased in diabetes and apolipoprotein AI is a major determinant of PLTP activity. There is also an independent association between CRP and PLTP activity, suggesting that subclinical inflammation may influence PLTP activity in diabetes.