Rotator cuff tears: preliminary application of high-resolution MR imaging with counter rotating current loop-gap resonators

A new class of radio frequency (RF) coils for magnetic resonance (MR) imaging and spectroscopy is introduced. The coils consist of two loop-gap resonators of equal diameters positioned along a common axis. They are tuned to the mode in which the current in the two loops flows in opposite directions. These coils are "decoupled" from a uniform excitation field of arbitrary orientation (including circularly polarized fields) by intrinsic decoupling and by means of back-to-back fast recovery diodes. Measurements made with the coils and a phantom saline tank indicate that the signal-to-noise ratio obtainable with these coils is almost identical to that obtained with single loops. Imaging of several anatomic areas, including knee, wrist, and shoulder, has been performed with a 1.5-T MR system that uses circularly polarized RF. A small series of patients with torn rotator cuffs underwent imaging. Difficulties in establishing the diagnosis with MR imaging because of anatomic complexity are illustrated. The value of pulse sequences with long repetition times to increase the signal intensity of fluid in the joint is shown.     

DNA mismatch repair (MMR)-dependent 5-fluorouracil cytotoxicity and the potential for new therapeutic targets

The metabolism and efficacy of 5-fluorouracil (FUra) and other fluorinated pyrimidine (FP) derivatives have been intensively investigated for over fifty years. FUra and its antimetabolites can be incorporated at RNA- and DNA-levels, with RNA level incorporation provoking toxic responses in human normal tissue, and DNA-level antimetabolite formation and incorporation believed primarily responsible for tumour-selective responses. Attempts to direct FUra into DNA-level antimetabolites, based on mechanism-of-action studies, have led to gradual improvements in tumour therapy. These include the use of leukovorin to stabilize the inhibitory thymidylate synthase-5-fluoro-2′-deoxyuridine 5′ monophoshate (FdUMP)-5,10-methylene tetrahydrofolate (5,10-CH₂FH₄) trimeric complex. FUra incorporated into DNA also contributes to antitumour activity in preclinical and clinical studies. This review examines our current state of knowledge regarding the mechanistic aspects of FUra:Gua lesion detection by DNA mismatch repair (MMR) machinery that ultimately results in lethality. MMR-dependent direct cell death signalling or futile cycle responses will be discussed. As 10–30% of sporadic colon and endometrial tumours display MMR defects as a result of human MutL homologue-1 (hMLH1) promoter hypermethylation, we discuss the use and manipulation of the hypomethylating agent, 5-fluorodeoxycytidine (FdCyd), and our ability to manipulate its metabolism using the cytidine or deoxycytidylate (dCMP) deaminase inhibitors, tetrahydrouridine or deoxytetrahydrouridine, respectively, as a method for re-expression of hMLH1 and re-sensitization of tumours to FP therapy.     

Anthropogenic osmium in rain and snow reveals global-scale atmospheric contamination

Osmium is one of the rarer elements in seawater, with typical concentration of ≈10 × 10⁻¹⁵ g g⁻¹ (5.3 × 10⁻¹⁴ mol kg⁻¹). The osmium isotope composition (¹⁸⁷Os/¹⁸⁸Os ratio) of deep oceans is 1.05, reflecting a balance between inputs from continental crust (≈1.3) and mantle/cosmic dust (≈0.13). Here, we show that the ¹⁸⁷Os/¹⁸⁸Os ratios measured in rain and snow collected around the world range from 0.16 to 0.48, much lower than expected (>1), but similar to the isotope composition of ores (≈0.2) that are processed to extract platinum and other metals to be used primarily in automobile catalytic converters. Present-day surface seawater has a lower ¹⁸⁷Os/¹⁸⁸Os ratio (≈0.95) than deep waters, suggesting that human activities have altered the isotope composition of the world''s oceans and impacted the global geochemical cycle of osmium. The contamination of the surface ocean is particularly remarkable given that osmium has few industrial uses. The pollution may increase with growing demand for platinum-based catalysts.     

Increased height in diabetes mellitus corresponds to the predicted and the adult height

This study was conducted to analyse the effect of childhood-onset diabetes mellitus on adult height. The height at time of diagnosis of 35 children with insulin-dependent diabetes mellitus (IDDM) was compared with growth reference data. Predictions of the adult height were made at the time of diagnosis using the target height and the Tanner-Whitehouse II method. The adult height was compared with both the predicted values and the height of healthy adults. The height at time of diagnosis of the prepubertal children was increased compared with growth reference data, in contrast to pubertal children who had normal heights. Only the prepubertal boys were taller at time of diagnosis. The adult height of the prepubertal patients was taller than growth reference data. The mean adult height in all patients did not differ significantly from the predicted heights. In conclusion, the increased height at the start of IDDM in prepubertal children persists until adulthood.     

人类牙乳头间充质细胞向成牙本质细胞定向的诱导分化

目的:探讨人牙乳头间充质细胞向成牙本质细胞的分化机制和分化过程。方法:实验于2004-04/2005-03在四川大学华西口腔医学院口腔生物医学工程教育部重点实验室完成。①实验材料:选择四川大学华西第二医院自然流产的三四个月胎龄的人胚胎(孕妇知情同意,经过医院伦理委员会批准),胰岛素样生长因子Ⅰ和碱性成纤维细胞生长因子(均购自美国Sigma公司)。②实验分组:实验分为空白对照组、胰岛素样生长因子Ⅰ组、碱性成纤维细胞生长因子组和联合组。③实验干预:在建立人牙乳头间充质细胞体外培养模型的基础上,用不含白血病抑制因子的DMEM/F12培养基作为基础培养液,分别用浓度为10μg/L的胰岛素样生长因子Ⅰ、浓度为100μg/L的碱性成纤维细胞生长因子以及同时用这两种因子诱导人牙乳头间充质细胞向成牙本质细胞定向分化。④实验评估:采用倒置显微镜、免疫细胞化学和反转录-聚合酶链反应等方法从形态学和功能方面检测细胞的变化。结果:①培养和诱导细胞形态学变化及碱性磷酸酶活性:诱导细胞培养7d时,联合组和胰岛素样生长因子Ⅰ组的培养细胞均呈现单一胞浆突起,形态上出现成牙本质样细胞改变,细胞的碱性磷酸酶活性明显增高,联合组细胞的胞浆突起更明显,细胞的碱性磷酸酶活性更高;碱性成纤维细胞生长因子组与对照组比较,细胞变化不明显。②细胞免疫化学结果:联合组和胰岛素样生长因子Ⅰ组牙本质涎磷蛋白的免疫细胞化学染色胞浆呈阳性。③细胞hDSPPmRNA的表达:联合组和胰岛素样生长因子Ⅰ组细胞经反转录-聚合酶链反应后获得约599bp的特异性片段,表明两组细胞在mRNA水平表达特异性牙本质涎磷蛋白。而其余两组未见表达。结论:胰岛素样生长因子Ⅰ能刺激人牙乳头间充质细胞向功能性成牙本质细胞样细胞分化,碱性成纤维细胞生长因子可产生协同作用。     

Detection of three types of hepatitis C virus in blood donors: investigation of type-specific differences in serologic reactivity and rate of alanine aminotransferase abnormalities

The serologic reactivity and epidemiology associated with different hepatitis C virus (HCV) variants were investigated in a cohort of 113 anti-HCV-positive donors. In Scotland, HCV type 1 accounted for one- half of all infections; 40 percent of subjects were infected with HCV type 3, and the remainder were infected with type 2. Reactivity with the NS-4-encoded antigens in the first-generation anti-c100 assay was absent in 68 percent of donors infected with types 2 and 3, as compared with 10 percent for those infected with type 1. Even when combined with surrogate marker testing, first-generation tests would have failed to detect 12 percent of HCV-infected blood donors. The age distribution, incidence of past infection with hepatitis B virus, and reported risk factors were similar in donors infected with types 1 and 3 (mean ages were 31.9 and 29.9; 18 and 17.5% were positive for antibody to hepatitis B core antigen; and 47 and 48% had past intravenous drug abuse). However, the distributions of alanine aminotransferase levels were significantly different in those infected with type 3 (abnormally raised in 83%) and those infected with type 1 (55% abnormal alanine aminotransferase; p < 0.05) or type 2 (60%; p < 0.01) and those who were nonviremic (8%; p < 0.0001). These data suggest that HCV type 1 is the most common HCV infection in blood donors and that infection with HCV type 3 may be associated with more severe liver disease, because of more recent infection or because of a greater inherent pathogenicity of type 3 variants.     

Analysis of a family of cyclin-dependent kinase inhibitors: p15/MTS2/INK4B, p16/MTS1/INK4A, and p18 genes in acute lymphoblastic leukemia of childhood

A newly recognized family of proteins that inhibit cyclin-dependent kinases (CDKs) termed cyclin-dependent kinase inhibitors (CDKI) have an important role in regulation of cell-cycle progression. A subfamily of these CDKIs (p15INK4B/MTS2, p16INK4/MTS1, and p18) have a high degree of structural and functional homology and are candidate tumor- suppressor genes. We evaluated the mutational status of the p15, p16, and p18 genes in 103 childhood acute lymphoblastic leukemia (ALL) samples and correlated these results with both their clinical data and additional results concerning their loss of heterozygosity in the region of the p15/p16 genes. Homozygous deletions of the p16 gene occurred extremely frequently in T-ALLs (17/22; 77%), and it was also frequent in precursor-B ALLs (12/81; 15%). Homozygous deletions of the p15 gene were also very frequent in T-ALLs (9/22; 41%), and it occurred in 5 of 81 (6%) precursor-B ALL samples. No deletions of p18 was found in any of the 103 ALL samples. Also, no point mutations of the p15, p16, and p18 genes were detected. We correlated p15/p16 alterations at diagnosis with their clinical characteristics as compared with 2,927 other patients treated similarly. Those with p15/p16 alterations were older; had higher white blood cell counts, often with T-cell ALL phenotype; and more frequently had a mediastinal mass at presentation; but they had the same nonremission, relapse, and survival rates at 5 years as did those patients whose blast cells did not have a p15/p16 deletion. To better understand the extent of alterations affecting chromosome 9p21 (location of the p15/p16 genes), loss of heterozygosity (LOH) was examined at D9S171, which is about 1 megabase proximal to the p15/p16 genes. LOH was detected in 15 of 37 (41%) informative samples. Interestingly, of the 24 informative samples that had no detectable alteration of the p15/p16 genes, 7 samples (29%) had LOH at D9S171. In summary, we show in a very large study that p15 and p16, but not p18, CDKI genes are very frequently altered in ALL; those with p15/p16 alterations are more frequently older children, have higher white blood cells at presentation, and often have a T-cell ALL phenotype. The LOH analysis suggests that another tumor-suppressor gene important in ALL also is present on chromosome 9p21.