The taq IA and Ser311Cys polymorphisms in the dopamine D2 receptor gene and obesity

Dopamine D2 receptors (DRD2) in the central nervous system are involved in the regulation of feeding. It remains to be elucidated if mutations in the DRD2 gene contribute to the development of obesity. The aim of the present study was to investigate whether the Taq IA and Ser311Cys polymorphisms in the DRD2 gene are associated with obesity in Nauruan and Australian subjects. Subjects were selected based on extremes of the body mass index (BMI) distribution. Two groups of Australian women were selected. The leanest group had a mean BMI of 22.5 kg/m2 (range: 20.3-24.3) and the heaviest group had a mean of 36.1 kg/m2 (32.5-44.1). Four groups of Nauruan subjects were selected. Leanest men had a mean BMI of 33.0 kg/m2 (28.4-36.9), heaviest men had a mean of 52.8 kg/m2 (46.5-69.2), leanest women had a mean of 34.8 kg/m2 (28.2-41.8) and heaviest women had a mean of 55.1 kg/m2 (49.3-73.8). Subjects were genotyped for the Taq IA and Ser311Cys polymorphisms using polymerase chain reaction (PCR) restriction fragment length polymorphism analysis and allelic discrimination TaqmanTM PCR respectively. Leanest and heaviest groups were examined for differences in genotype frequency. Taq IA and Ser311Cys genotype frequencies did not differ significantly between leanest and heaviest Nauruan groups, or between leanest and heaviest Australians. Haplotype frequencies of these polymorphisms did not differ between leanest and heaviest groups. The Taq IA and Ser311Cys polymorphisms in the DRD2 gene are unlikely to be common causes of obesity in these populations.

Liver cell transplantation leads to repopulation and functional correction in a mouse model of Wilson's disease

Background and Aim: The toxic milk (tx) mouse is a non-fatal animal model for the metabolic liver disorder, Wilson's disease. The tx mouse has a mutated gene for a copper-transporting protein, causing early copper accumulation in the liver and late accumulation in other tissues. The present study investigated the efficacy of liver cell transplantation (LCT) to correct the tx mouse phenotype.

Methods: Congenic hepatocytes were isolated and intrasplenically transplanted into 3–4-month-old tx mice, which were then placed on various copper-loaded diets to examine its influence on repopulation by transplanted cells. The control animals were age-matched untransplanted tx mice. Liver repopulation was determined by comparisons of restriction fragment length polymorphism ratios (DNA and mRNA), and copper levels were measured by atomic absorption spectroscopy.

Results: Repopulation in recipient tx mice was detected in 11 of 25 animals (44%) at 4 months after LCT. Dietary copper loading (whether given before or after LCT, or both) provided no growth advantage for donor cells, with similar repopulation incidences in all copper treatment groups. Overall, liver copper levels were significantly lower in repopulated animals (538 ± 68 µg/g, n = 11) compared to non-repopulated animals (866 ± 62 µg/g, n = 14) and untreated controls (910 ± 103 µg/g, n = 6; P < 0.05). This effect was also seen in the kidney and spleen. Brain copper levels remained unchanged.

Conclusion: Transplanted liver cells can proliferate and correct a non-fatal metabolic liver disease, with some restoration of hepatic copper homeostasis after 4 months leading to reduced copper levels in the liver and extrahepatic tissues, but not in the brain.

Relationship of glutathione S-transferase genotypes with side-effects of pulsed cyclophsphamide therapy in patients with systemic lupus erythematosus

Aims
Cyclophosphamide (CTX) is an established treatment of severe systemic lupus erythematosus (SLE). Cytotoxic CTX metabolites are mainly detoxified by multiple glutathione S-transferases (GSTs). However, data are lacking on the relationship between the short-term side-effects of CTX therapy and GST genotypes. In the present study, the effects of common GSTM1, GSTT1, and GSTP1 genetic mutations on the severity of myelosuppression, gastrointestinal (GI) toxicity, and infection incidences induced by pulsed CTX therapy were evaluated in patients SLE.
Methods
DNA was extracted from peripheral leucocytes in patients with confirmed SLE diagnosis (n = 102). GSTM1 and GSTT1 null mutations were analyzed by a polymerase chain reaction (PCR)-multiplex procedure, whereas the GSTP1 codon 105 polymorphism (Ile→Val) was analyzed by a PCR-restriction fragment length polymorphism (RFLP) assay.
Results
Our study demonstrated that SLE patients carrying the genotypes with GSTP1 codon 105 mutation [GSTP1*-105I/V (heterozygote) and GSTP1*-105 V/V (homozygote)] had an increased risk of myelotoxicity when treated with pulsed high-dose CTX therapy (Odds ratio (OR) 5.00, 95% confidence interval (CI) 1.96, 12.76); especially in patients younger than 30 years (OR 7.50, 95% CI 2.14, 26.24), or in patients treated with a total CTX dose greater than 1.0 g (OR 12.88, 95% CI 3.16, 52.57). Similarly, patients with these genotypes (GSTP1*I/V and GSTP1*V/V) also had an increased risk of GI toxicity when treated with an initial pulsed high-dose CTX regimen (OR 3.33, 95% CI 1.03, 10.79). However, GSTM1 and GSTT1 null mutations did not significantly alter the risks of these short-term side-effects of pulsed high-dose CTX therapy in SLE patients.
Conclusions
The GSTP1 codon 105 polymorphism, but not GSTM1 or GSTT1 null mutations, significantly increased the risks of short-term side-effects of pulsed high-dose CTX therapy in SLE patients. Because of the lack of selective substrates for a GST enzyme phenotyping study, timely detection of this mutation on codon 105 may assist in optimizing pulsed high-dose CTX therapy in SLE patients.

Genetic polymorphisms of cytochrome P450 2B6 gene in Han Chinese

Cytochrome P450 (CYP2B6) is an important enzyme that metabolizes more than eight compounds and about 3.0% of therapeutic drugs. The genetic polymorphisms of CYP2B6 have earlier been studied in Caucasian, Japanese and Korean, but the data are lacking for Han Chinese. The aim of this study was to investigate the frequencies of allelic variants of CYP2B6 in healthy Han Chinese and compare with those in other ethnic groups reported in the literature. Polymerase chain reaction (PCR)–restriction fragment length polymorphism (RFLP) method was used to test the five common non-synonymous single nucleotide polymorphisms (SNPs) of CYP2B6 gene, namely, 64C > T, 516G > T, 777C > A, 785A > G and 1459C > T in unrelated healthy Han Chinese (n = 193). The study demonstrated that the frequencies of 64C > T, 516G > T, 777C > A, 785A > G and 1459C > T SNPs in Han Chinese were 0.03, 0.21, 0, 0.28 and 0.003, respectively. The frequencies of all five SNPs tested in female were higher than those in male, but the statistical difference was insignificant (P > 0.05). Compared to the data reported in the literature, the frequencies of common CYP2B6 allelic variants in Chinese are similar to those of other Asian populations including Japanese and Korean, but markedly different from those in Caucasians. These results indicate the presence of marked ethnic difference in CYP2B6 SNP frequencies between Chinese and Caucasian. Further studies are required to explore the impact of these SNPs of CYP2B6 gene on the clinical response (efficacy and toxicity) to drugs that are substrates for CYP2B6 in patients.

Relationship between genotype and enzyme activity of glutathione S-transferases M1 and P1 in Chinese

Glutathione S-transferases (GSTs) are the major detoxifying Phase II enzyme for eliminating electrophilic compounds. Mutations in GSTM1, GSTP1 and GSTT1 in Caucasian and GSTA1 in Chinese have been found to reduce enzyme activity. However, data on the impact of common genetic polymorphisms of GSTM1 and GSTP1 on enzyme activity in Chinese is lacking. This study aimed to investigate the effect of common GSTP1 and GSTM1 polymorphisms on erythrocyte GST activity in healthy Chinese (n = 196). GSTM1 null mutation (GSTM1*0) was analyzed by a PCR-Multiplex procedure, whereas GSTP1 313A → G polymorphism (resulting in Ile105Val at codon 105) was analyzed by PCR-restriction fragment length polymorphism (RFLP) analysis. Erythrocyte GST activity was measured using 1-chloro-2,4-dinitro-bezene (CDNB) as the model substrate. The frequency of GSTM1 null genotype was 54.3% and the frequency of GSTP1-Ile/Ile, -Ile/Val, and -Val/Val genotype was 60.7%, 35.2% and 4.1%, respectively, with a frequency of 21.7% for the 105 valine allele. Age, gender and smoking did not significantly affect the erythrocyte GST activities. The mean erythrocyte GST enzyme activity for GSTP1*-Ile/Val genotype group (3.53 ± 0.63 U/g Hb) was significantly lower than that for subjects with GSTP1-Ile/Ile genotype (4.25 ± 1.07 U/g Hb, P = 0.004), while subjects with the GSTP1-Val/Val genotype had the lowest enzyme activity (2.44 ± 0.67 U/g Hb). In addition, the GST activity in carriers of GSTM1*0/GSTP1-Ile/Ile was significantly higher than that of subjects inherited GSTM1*0/GSTP1-Ile/Val or GSTM1*0/GSTP1-Val/Val. However, there is no association between GSTM1 null mutation and reduced enzyme activity. GSTP1 codon 105 mutation led to reduced erythrocyte GST activity in Chinese. A combined GSTP1 and GSTM1 null mutations also resulted in significantly reduced GST activity. Further studies are needed to explore the clinical implications of GSTM1 and GSTP1 polymorphisms.

A novel approach to the functionalisation of pristine carbon fibre using azomethine 1,3-dipolar cycloaddition

We demonstrate the utilisation of an azomethine 1,3-dipolar cycloaddition reaction with carbon fibre to graft complex molecules onto the fibre surface. In an effort to enhance the interfacial interaction of the fibre to the matrix, the functionalised fibres possessed a pendant amine that is able to interact with epoxy resins. Functionalisation was supported by X-ray photoelectron spectroscopy and the grafting process had no detrimental effects on tensile strength compared with the control (untreated) fibres. Also, microscopic roughness (as determined by atomic force microscopy) and fibre topography were unchanged after the described treatment process. This methodology complements existing methodology aimed at enhancing the surface of carbon fibres for advanced material applications while not compromising the desirable strength profile. Single-fibre fragmentation tests show a statistically significant decrease in fragment length compared with the control fibres in addition to transverse cracking within the curing resin, both of which indicate an enhanced interaction between fibre and resin.

The effect of flicker from fluorescent lights on mate choice in captive birds

The visual systems of birds are hypothesized to have higher temporal resolution than those of humans, suggesting that they may be able to perceive the flicker emitted from conventional low-frequency fluorescent lights (LF; 100 Hz in Europe, 120 Hz in the U.S.A.). These lights are commonly used in the housing of captive birds and this may affect both their welfare and performance in experiments. We carried out mate choice experiments on European starlings, Sturnus vulgaris, under both low- and high-frequency fluorescent lights (HF; > 30 kHz, at which flicker is imperceptible). Indicators of male condition and size, together with the reflectance spectra and length of the males' throat feathers, were also recorded to ascertain which variables correlated with female preference. Females ranked males consistently under HF, but not LF, lighting, and individual females chose different males under the two lighting types. Under HF lighting, females chose to spend more time with males that had longer throat feathers. The flicker rate of the light clearly affected the choices made by the females, possibly because of nonspecific stress effects or decreased discrimination ability. Our results imply that careful interpretation of mate choice experiments is needed, especially with regard to the lighting types used, to elucidate the real cause behind any variation shown. (c) 2006 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.