G/G Translocation and chronic myelocytic leukaemia

Summary A previously reported case of chronic myelocytic leukaemia was re-examined using the new methods of chromosome staining. The analysis confirmed our former assumption that in this case the Phl is the result of a G/G translocation and established that the chromosomes involved are members of the groups 21 and 22.

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Zusammenfassung Ein früher berichteter Fall von chronisch myeloischer Leukämie wurde unter Verwendung der neuen Methoden der Chromosomenanfärbung erneut untersucht. Die Analyse bestätigte unsere frühere Annahme, daß in diesem Fall die Phl das Ergebnis einer G/G Translokation ist und erhärtete die Tatsache, daß die beteiligten Chromosomen Mitglieder der Gruppen 21 und 22 sind.

     

G & A

编者按: 春节将至,很多糖友又开始担心过节的饮食问题了.每到这个时候,吃饭对于糖友来说,都足一件紧张的事情,生怕在春节期间血糖控制得不理想.这期邀请中南大学湘雅二医院营养科主任唐大寒医师给大家几点饮食建议:     

Hepatitis G virus

A number of new hepatitis viruses （G, TT, SEN） were discovered late in the past century. We review the data available in the literature and our own findings suggesting that the new hepatitis G virus （HGV）, disclosed in the late 1990s, has been rather well studied. Analysis of many studies dealing with HGV mainly suggests the lymphotropicity of this virus. HGV or GBV-C has been ascertained to influence course and prognosis in the HIV-infected patient. Until now, the frequent presence of GBV-C in coinfections, hematological diseases, and biliary pathology gives no grounds to determine it as an ＂accidental tourist＂ that is of no significance. The similarity in properties of GBV-C and hepatitis C virus （HCV） offers the possibility of using HGV, and its induced experimental infection, as a model to study hepatitis C and to develop a hepatitis C vaccine.     

Definition of the mutations of G6PD Wayne, G6PD Viangchan, G6PD Jammu, and G6PD 'LeJeune'.

We report the nucleotide (nt) substitutions of four unrelated glucose-6-phosphate dehydrogenase (G6PD)-deficient males. Only the mutation of G6PD Wayne was unique. It was a nt 769 C----G substitution causing a deduced substitution of glycine for arginine at amino acid 257. This mutation is in a region in which G6PD mutations have previously been associated with chronic hemolytic anemia. The mutation of G6PD Jammu and G6PD Viangchan were identical: a G----A mutation at nucleotide 871, predicting a Val----Met substitution at amino acid 291. However, these two variants differ with respect to the 1311 polymorphism, suggesting that they may have arisen independently. Enzyme from a child with chronic hemolytic anemia, designated G6PD 'LeJeune', proved to be due to a G----T substitution at nt 637, a change identical with that in 3 unrelated patients who had been reported previously as having G6PD Gastonia, Minnesota and Marion. These findings support the suggestion that both polymorphic and sporadic G6PD deficiency mutations in unrelated persons with G6PD deficiency are often the same, even when thought to be distinct on the basis of biochemical characterization.     

Heterotrimeric G proteins precouple with G protein-coupled receptors in living cells

Using fluorescence resonance energy transfer (FRET) microscopy, we investigate how heterotrimeric G proteins interact with G protein-coupled receptors (GPCRs). In the absence of receptor activation, the alpha2A adrenergic and muscarinic M4 receptors are present on the cell membrane as dimers. Furthermore, there is an interaction between the G protein subunits alpha o, beta1, and gamma2 and a number of GPCRs including M4, alpha2A, the adenosine A1 receptor, and the dopamine D2 receptor under resting conditions. The interaction between GPCRs and Galpha proteins shows specificity: there is interaction between the alpha2A receptor and Go, but little interaction between the alpha2A receptor and Gs. In contrast, the predominantly Gs-coupled prostacyclin receptor interacted with Gs, but there was little interaction between the prostacyclin receptor and Go. Inverse agonists did not change the FRET ratio, whereas the addition of agonist resulted in a modest fall. Our work suggests that GPCR dimers and the G protein heterotrimer are present at the cell membrane in the resting state in a pentameric complex.     

Prothrombin A19911G and G20210A polymorphisms' role in thrombosis

The prothrombin G20210A polymorphism, which correlates with the plasmatic prothombin levels, is the second genetic risk factor for deep venous thrombosis (DVT), although its prothrombotic role is mild. Recently, the prothrombin A19911G polymorphism, also associated with slight variations of the prothrombin level, has been suggested to modulate the thrombotic risk of the G20210A polymorphism in a preliminary study including few patients and controls. Our study evaluated the effect of the A19911G polymorphism in the arterial and venous thrombotic risk of the prothrombin 20210G/A genotype, analysing 204 consecutive DVT patients and 204 matched controls. Moreover, we analysed 213 carriers of the 20210G/A genotype (152 with DVT, 26 with arterial thrombosis and 35 healthy subjects) and 10 homozygous 20210 A/A carriers. We developed a simple method to simultaneously determine the genotype of both polymorphisms. In accordance with our case/control study, the A19911G polymorphism did not play a significant role in the development of DVT. Analysis of 120 20210 A alleles demonstrated a complete linkage disequilibrium with the 19911 A allele. These polymorphisms (alone or combined) did not modify the risk of arterial thrombosis. However, the 19911A/G genotype slightly increased the risk of developing DVT in carriers of the 20210G/A genotype (OR 3.34 vs 5.86), supporting that the prothrombin 19911 polymorphism could modulate the risk of the G20210A polymorphism in developing DVT.     

GROUP G STREPTOCOCCAL ARTHRITIS

Six cases of Lancefield Group G streptccocal arthritis are described.Two cases had pre-existing chronic arthritis (one rheumatoid).withinfection of a joint prosthesis. Three cases had neoplasticdisease before or at the same time as septic arthritis. Skinreactions, including cellulitis and sacrlatiniform rash, wereprominent in five cases. ONe patient may have acquired a GroupG streptococcus from her dog. Five cases reponded well to penicillinand the sixth who was allergic to that drug was cured by erythromycin.This unusual cause of septic arthritis is being recognized morefrequently in the United Kingdom.     

Replicatively senescent cells are arrested in G1 and G2 phases

Most human somatic cells do not divide indefinitely but enter a terminal growth arrest termed replicative senescence. Replicatively senescent cells are generally believed to arrest in G1 or G0 stage of the cell cycle. While doing cell cycle analysis on three different lines of normal human fibroblasts we observed that 36-60% of the replicatively senescent cells had 4N DNA content. Only up to 5% of senescent cells had more than one nucleus ruling out the possibility that the 4N cell population were G1-arrested bi-nucleated cells. Furthermore, it is unlikely that the 4N cells are tetraploids, because actively dividing pre-senescent cultures lacked the 8N tetraploid G2 population. Collectively these results suggest that the 4N population consists of G2 arrested cells. The notion that a large fraction of senescent cell population is arrested in G2 is important for understanding the biology of replicative senescence.     

载脂蛋白AI基因启动子区域G→A置换 与冠心病关系的研究

目的探讨载脂蛋白AI(apoAI)基因启动子区域—78bp位点G→A置换与血浆高密度脂蛋白(HDL)含量及冠心病(CHD)的关系。方法PCR扩增apoAI基因启动子—259至—1bpDNA片段,限制性内切酶MspI酶切的PCR产物,3％琼脂糖凝胶电泳分离酶切后的DNA,确定基因型。结果共检测CHD患者169例(CHD组),健康对照者115例(正常对照组)。两组间基因型及等位基因频率分布差异无显著性意义。总体看基因型不影响血浆apoAI及高密度脂蛋白胆固醇(HDL－C)水平。在cHD伴HDL－c低下的患者中,AA型纯合子例数,尤其是男性患者高于正常对照者(P=0.0028)。结论AA纯合子并伴有HDL－C低下的男性患者患CHD的危险性可能会增加,应予以重视。