彻罗基族印地安儿童及青少年的体重指数和高密度脂蛋白

美国原著民易于出现胰岛素抵抗及相关的心血管病风险。因此，笔者对彻罗基族儿童和青少年的体重指数（BMI）是否与HDL—C（HDL胆固醇）、HDL微粒Lp（脂蛋白）A-Ⅰ和LpA-Ⅰ：A-Ⅰ相关进行了研究。在三个性别特异的年龄段（5～9岁，10～14岁和15～19岁）内按照BMIZ值的四分位值对研究对象进行分组，研究其肥胖和年龄相关的脂蛋白和HOMA—IR（HOMA模型胰岛素抵抗指数）值的趋势。在两个性别的三个年龄组中，HDL—C随着BMIZ值的四分位值的增加而降低。HDL-C、LpA-Ⅰ和LpA-Ⅰ：A-Ⅱ在男孩中随着年龄增加而降低，在女孩中则没有观察到该变化。在两个性别的三个年龄组中，Log HOMA-IR随着BMIZ值的四分位值的增加而增加。线性回归模型显示BMIZ值、甘油三酯和年龄与HDL—C相关，     

Effects of delta-9-tetrahydrocannabinol on cultured HeLa cell growth and development

Monolayer cultures of HeLa cells were used to monitor the effects of non-lethal concentrations of delta-9-tetrahydrocannabinol (delta-9-THC) on the pool sizes of the acid-soluble and acid-insoluble DNA moieties and cytoplasmic RNA pool sizes. The DNA fractions were separated using acid precipitation and low speed centrifugation, while the RNA was examined through the use of sucrose gradients and high speed ultracentrifugation. The ratio of acid-insoluble to acid-soluble DNA per cell in untreated HeLa cells is 16:1, which did not change appreciably following delta-9-THC treatment. However, cell division was retarded as much as 25% in the 24 hours treatment period indicating that nucleic acid synthesis, while not inhibited, is depressed by delta-9-THC. This is not related to cell death as indicated by cell viability (> 95%). At both 1.0 x 10(-5)M and 3.2 x 10(-7)M, delta-9-THC caused a marked change in the free ribosomal RNA (an increase with 3.2 x 10(-7)M and a decrease with the 10(-5)M), total ribosomal RNA (a decrease with both observed delta-9-THC concentrations) and non-sedimental RNA (an increase with both observed delta-9-THC concentrations).     

Chemically-induced histone modification as a predictor of carcinogenicity

The interaction between carcinogens and DNA is believed to initiate neoplastic transformation, but evidence suggests that epigenetic mechanisms may also be of importance. Because the histone proteins have important roles in chromatin structure and cellular function, they provide a reasonably well understood epigenetically-based system for the detection of carcinogens. In this study, human foreskin fibroblastic cells were exposed to one of several mutagens and/or carcinogens for 3, 12, or 24 h to determine if induced histone modification may be a means of predicting chemical carcinogenicity.Butyric acid (5 mM), known to result in acetylation of histones H3 and H4, and 12-O-tetradecanoylphorbol-13-acetate (3 M), known to result in phosphorylated histone H1, were tested initially. Electrophoresis of the histone fractions was capable of resolving multiple forms of histones H1, H3, and H4.Propane sultone (0.1 mM) induced a broadening of the H2A and H2B bands after a 24 h exposure and carbon tetrachloride (1 mM) induced the formation of new histone forms in the H1 fraction after 24 h and in the H3 fraction after 3 h. Experimental variability limited the statistically significant modifications to carbon tetrachloride and propane sultone, two known carcinogens, where new forms of modified histone were detected. Therefore, the histone modification assay, with further experimentation, may be an alternate method of detecting carcinogens, especially when conventional genotoxic tests prove unreliable.     

The role of the radiology nurse

The radiology nurse's role requires a high level of knowledge, expertise and independence because the department provides services to a wide variety of patients with diverse needs and about whom information may be limited. Radiology nurses routinely start or check peripheral i.v.s, assess infusaports, administer medications, monitor vital signs, suction patients, insert foleys and help patients with their personal needs. The nurse also informs the technologist or radiologist of any unusual patient needs and performs specialized nursing duties, such as administering i.v. sedation or analgesia during special procedures and closely monitoring patients with cardiac/pulse oximeters. Radiology departments call on nurses to care for patients transported from intensive care, patients in emergency situations and pediatric patients and others needing sedation. Teaching is another duty radiology nurses assume, instructing patients and their families, students, technologists, other nurses, radiologists and physicians about patient care. They also teach the radiology staff new nursing policies and national standards as such changes occur. Radiology nurses devote a lot of time to quality improvement and infection control programs: collecting data, keeping records and reporting results. Because radiology nursing is relatively new, the nurse may be called upon to help write patient care policies, design flowsheets or patient instruction sheets and develop protocols or care plans. Radiology nurses utilize skills employed in many other nursing specialties and incorporate them in the radiology setting. They must provide quality nursing care to a large, transient group of patients of all ages, be a spokesperson for patient care and a teacher to other radiology staff members on patient care issues.     

Reconstruction of the anterior and posterior cruciate ligaments after knee dislocation. Results using fresh-frozen nonirradiated allografts

We reviewed the results in 13 patients who underwent simultaneous allograft reconstruction of both the anterior and posterior cruciate ligaments after a knee dislocation (nine acute and four chronic injuries). Seven patients sustained related medial collateral ligament injuries and six patients had posterolateral complex injuries. Ligament reconstructions were performed using fresh-frozen Achilles or patellar tendon allografts. At follow-up evaluation (mean of 38 months), only one patient described the reconstructed knee as normal. Six patients had returned to unrestricted sports activities and four had returned to modified sports. The average extension loss was 3 degrees (range, 0 degree to 10 degrees) and average flexion loss was 5 degrees (range, 0 degree to 15 degrees). The KT-1000 arthrometer measurements at 133 N anterior-posterior tibial load showed a mean side-to-side difference of 4.5 mm (range, 0 to 10) at 20 degrees and 5.0 mm (range, 0 to 9) at 70 degrees. The mean Lysholm score was 88 (range, 42 to 100). International Knee Documentation Committee ratings were six nearly normal, five abnormal, and one grossly abnormal. Two patients required manipulations for knee stiffness. This study demonstrates that reconstruction of both cruciate ligaments can restore stability sufficient to allow sports activity in most patients with knee dislocations, but "normal" results are difficult to achieve.     

Chromosome-specific NOR inactivation explains selective rRNA gene silencing and dosage control in Arabidopsis

In eukaryotes, scores of excess ribosomal RNA (rRNA) genes are silenced by repressive chromatin modifications. Given the near sequence identity of rRNA genes within a species, it is unclear how specific rRNA genes are reproducibly chosen for silencing. Using Arabidopsis thaliana ecotype (strain) Col-0, a systematic search identified sequence polymorphisms that differ between active and developmentally silenced rRNA gene subtypes. Recombinant inbred mapping populations derived from three different ecotype crosses were then used to map the chromosomal locations of silenced and active RNA gene subtypes. Importantly, silenced and active rRNA gene subtypes are not intermingled. All silenced rRNA gene subtypes mapped to the nucleolus organizer region (NOR) on chromosome 2 (NOR2). All active rRNA gene subtypes mapped to NOR4. Using an engineered A. thaliana line in which a portion of Col-0 chromosome 4 was replaced by sequences of another ecotype, we show that a major rRNA gene subtype silenced at NOR2 is active when introgressed into the genome at NOR4. Collectively, these results reveal that selective rRNA gene silencing is not regulated gene by gene based on mechanisms dependent on subtle gene sequence variation. Instead, we propose that a subchromosomal silencing mechanism operates on a multimegabase scale to inactivate NOR2.