Toll-like receptor 3 gene polymorphisms in South African Blacks with type 1 diabetes

Type 1 diabetes is the consequence of exposure of genetically susceptible individuals to specific environmental precipitants. The innate immune system provides the initial response to exogenous antigen and links with the adaptive immune system. The aim of this study was to assess the role of polymorphisms occurring in the cytoplasmic region of toll-like receptor (TLR) 3 gene and immediate 5' sequence, in subjects of Zulu descent with type 1 diabetes in KwaZulu-Natal, South Africa. Seventy-nine subjects with type 1 diabetes and 74 healthy normal glucose tolerant gender-matched control subjects were studied. Parts of exon 4 and exon 3/intron 3 of the TLR3 gene were studied by polymerase chain reaction, direct sequencing and restriction enzyme digestion with Bts 1. Of the nine polymorphisms studied, a significant association with type 1 diabetes was found for the major allele in the 2593 C/T polymorphism and for the minor alleles in the 2642 C/A and 2690 A/G polymorphisms, which were found to be in complete linkage disequilibrium. Correction of the P-values for the number of alleles studied, however, rendered the results no longer significant. These results suggest that polymorphisms in the TLR3 gene, which is part of the innate immune system, may be associated with type 1 diabetes in this population.     

Mutation analysis in 16 patients with mtDNA depletion

Sixteen unrelated Southern European patients with the mitochondrial depletion syndrome (MDS) were analyzed for mutations in the TK2 and DGUOK genes. Three novel mutations were identified in TK2 (R183G, R254X, and 142insG). When we analyzed additional genes involved in the dNTPs pool, such as SLC25A19 (DNC) and NT5M (d-NT2), we did not detect mutations. The current study suggest that scanning the TK2, DGUOK, SLC25A19, and NT5M genes is likely to help about 10% of MDS families in terms of genetic counseling. Also, our findings indicate that genotype-phenotype correlations are not straightforward in MDS.     

No evidence of PEG1/MEST gene mutations in Silver‐Russell syndrome patients

Silver‐Russell syndrome (SRS) is characterized by prenatal and postnatal growth retardation with morphologic anomalies. Maternal uniparental disomy 7 has been reported in some SRS patients. PEG1/MEST is an imprinted gene on chromosome 7q32 that is expressed only from the paternal allele and is a candidate gene for SRS. To clarify its biological function and role in SRS, we screened PEG1/MEST abnormalities in 15 SRS patients from various standpoints. In the lymphocytes of SRS patients, no aberrant expression patterns of two splice variants (α and β) of PEG1/MEST were detected when they were compared with normal samples. Direct sequence analysis failed to detect any mutations in the PEG1/MEST α coding region, and there were no significant mutations in the 5′‐flanking upstream region containing the predicted promoter and the highly conserved human/mouse genomic region. Differential methylation patterns of the CpG island for PEG1/MEST α were normally maintained and resulted in the same pattern as in the normal control, suggesting that there was no loss of imprinting. These findings suggest that PEG1/MEST can be excluded as a major determinant of SRS. © 2001 Wiley‐Liss, Inc.     

Increased fluidity of Plasmodium berghei-infected mouse red blood cell membranes detected by electron spin resonance spectroscopy

The fluidity of Plasmodium berghei-infected mouse red cell membranes is increased over that of uninfected cells at both 24°C and 37°C. This was demonstrated by electron spin resonance spectroscopy using the hydrocarbon spin labels 2-dodecyl-2′,5,5′-trimethyloxazolidine-N-oxyl and 2-heptyl-2′ -hexyl-5,5′-dimethyloxazolidine-N-oxyl to label regions of the bilayer near its surface, and deeper within the hydrocarbon region, respectively. Arrhenius plots of the ‘empirical motion parameter’ (R_i) obtained from 2-heptyl-2′-hexyl-5,5′-dimethyloxazolidine-N-oxyl-labeled cells versus temperature over the range from 0 to 45°C showed an hysteretic behavior of the spin labels in the membranes of both mature and immature uninfected cells. Such hysteretic behavior was consistently lacking in membranes of infected cells. These differences in membrane fluidity and spin label behavior are interpreted to reflect biochemical modifications of the red cell membrane which occur with infection by the malarial parasite.     

敌枯双对雄性小鼠生殖细胞分裂比率及精原细胞染色体畸变的影响

本文研究丁敌枯双对BALB/C雄性小鼠生殖细胞分裂比率及精原细胞染色体畸变的影响。将实验小鼠随机分为三组,即实验组(敌枯双组),阳性对照组(环磷酰胺组)和阴性对照组(双蒸水组)。结果发现:敌枯双能明显诱发精原细胞多倍体率和裂隙率增加,抑制终变期/中期Ⅰ和中期Ⅱ细胞的减数分裂比率,促进精原细胞有丝分裂比率。实验结果还提示:在遗传毒理检测中亚急性实验是必要的,并对实验结果进行了初步讨论。     

Metachromatic leukodystrophy caused by a partial cerebroside sulfatase defect

A patient with neuropathy and myopathy since infancy but whose neuropathy had been stable for a number of years showed a profound deficiency of arylsulfatase A in leukocytes and urine. Urine contained material that stained metachromatically and cochromatographed with cerebroside sulfate. In contrast, cultured fibroblasts contained about 10-20% of normal arylsulfatase A with properties identical to properties of normal fibroblast enzyme, except that it showed no cerebroside sulfatase activity. Growing fibroblasts in the cerebroside sulfate loading test had an attenuated rate of sulfatide hydrolysis. A re-examination of the cerebroside sulfatase reaction revealed that while only limited hydrolysis occurred with low concentrations of taurodeoxycholate or cholate (type I activation), significant hydrolysis of the natural substrate did take place with high concentrations of cholate (type II activation). This suggests that there is a partial cerebroside sulfatase defect in this atypical form of metachromatic leukodystrophy.     

Eosinophil traffic in the circulation following allergen challenge

BACKGROUND: Eosinophils contribute to the pathogenesis of asthma and localize to the lung after allergen exposure by uncertain mechanisms. METHODS: We used intrabronchial instillation of allergen to model the interaction between inhaled allergen and the lung. We measured the number of peripheral blood leukocytes and the expression of VLA-4 (CD49d), Mac-1 (CD11b) and PSGL-1 (CD162) up to 4 h after instillation of allergen into a bronchus of eight atopic asthmatics. For controls, we instilled normal saline into a subset of the asthmatic subjects, and allergen into nonatopic, nonasthmatic subjects. RESULTS: There were changes of total leukocyte number, number of polymorphonuclear leukocytes, lymphocytes, monocytes and eosinophils in all three groups (atopic asthmatics instilled with allergen, atopic asthmatics instilled with saline, nonatopic nonasthmatic subjects instilled with allergen), which were likely related to bronchoscopy. However, the decrease of eosinophils was significant only in the atopic asthmatics instilled with allergen. The remaining eosinophils in the allergen challenged asthmatics were not activated as defined by cell density or change of expression of VLA-4, Mac-1 and PSGL-1. CONCLUSIONS: While eosinophils rapidly and specifically leave the circulation after allergen challenge of atopic asthmatics, the remaining circulating eosinophils are not activated.