Structural insights into the assembly of the 30S ribosomal subunit in vivo: functional role of S5 and location of the 17S rRNA precursor sequence

The in vivo assembly of ribosomal subunits is a highly complex process, with a tight coordination between protein assembly and rRNA maturation events, such as folding and processing of rRNA precursors, as well as modifications of selected bases. In the cell, a large number of factors are required to ensure the efficiency and fidelity of subunit production. Here we characterize the immature 30S subunits accumulated in a factor-null Escherichia coli strain (∆rsgA∆rbfA). The immature 30S subunits isolated with varying salt concentrations in the buffer system show interesting differences on both protein composition and structure. Specifically, intermediates derived under the two contrasting salt conditions (high and low) likely reflect two distinctive assembly stages, the relatively early and late stages of the 3' domain assembly, respectively. Detailed structural analysis demonstrates a mechanistic coupling between the maturation of the 5' end of the 17S rRNA and the assembly of the 30S head domain, and attributes a unique role of S5 in coordinating these two events. Furthermore, our structural results likely reveal the location of the unprocessed terminal sequences of the 17S rRNA, and suggest that the maturation events of the 17S rRNA could be employed as quality control mechanisms on subunit production and protein translation.

Visuospatial-visuoconstructional ability in mild cognitive impairment / 中华神经科杂志

Objective To investigate visuospatial-visuoconstructional ability in patients with mild cognitive impairment(MCI).Methods The subjects were divided into three groups:122(51 males and 71 females)in the normal control group; 205(95 males and 110 females)in the MCI group,including 133 amnestic MCI(aMCI)and 72 non-amnestic MCI(naMCI),and 75(36 males and 39 females)in the Alzheimer' s disease(AD)group.The subjects were assessed for visuospatial-visuoconstructional ability by three tests:Rey-Osterrieth Complement Fixation Test(CFT),Clock Drawing Task(CDT),and Stick Test.Mini-mental State Examination(MMSE)was also performed in all groups.SPSS 11.5 statistical software was used for statistic analysis; Chi-square test was used to analyze enumeration data; One-way analysis of variance was used in pairwise comparison between the groups,and Bonferroni and LSD methods were used for multiple comparison.Results(1)The average MMSE score in the normal control group,MCI group and AD group was 28.24 ± 1.74,27.39 ± 1.83 and 19.98 ±3.23,respectively.(2)In the normal control group,either CFT imitating score or total CDT score had no obvious correlation with age or education,while Stick Test-Rotating part(STR)was correlated with age(r =-0.179,P ＜ 0.05),but had no significant correlation with education.(3)There were correlations between CFT imitating score and total CDT score (r =0.337),CFT imitating score and STR(r =0.232),and total CDT score and STR(r =0.235).The correlations were statistically significant(P ＜ 0.01).(4)CFT imitating and total CDT showed the greatest correlation with Trail Making Test B and Stroop Color Word Test Card C time consumption,an indicator of executive function.STR had greatest correlation with Auditory Verbal Learning Test,an index of memory.There were significant differences in CFT imitating,total CDT score and STR among the normal,MCI and AD groups(P ＜ 0.01).(5)STR is a more informative test to be used in diagnosis of MCI than CFT imitating and total CDT score,as shown by comparison of these tests in three subjects groups.Conclusion Visuospatial-visuoconstructional ability impairment is one of the symptoms of MCI.In detection of MCI,the assessment of space rotating ability is better than CFT imitating and total CDT score.

Correlation between serum albumin level and intestinal mucosa change in rats with cerebral hemorrhage / 中华神经科杂志

Objective To explore the correlation between the serum albumin level and the jejunal mucosal morphology in rats with cerebral hemorrhage and to find out the mechanism of the resulting hypoproteinemia.Methods A rat model of cerebral hemorrhage was used to detect the serum albumin level and the morphologic parameters of jejunal mucosa on day 1,7 and 14 after the hemorrhage.The results were compared to the normal control group and the sham-operated group. The correlation between the serum albumin level and the parameters of the jejunal mucosal morphology was explored.Results The serum albumin level was positively correlated with the small intestinal villous height(r =0.869,P＜0.01),villous area(r=0.659,P＜0.01),mucosal thickness (r=0.915,P＜0.01),depth of intestinal glands(r=0.545,P＜0.05)and density of intestinal glands(r=0.475,P＜0.05).Conclusion The serum albumin level is closely related to the morphologic changes of the jejunal mucosa.

Effects of growth hormone on serum albumin levels and intestinal mucosal morphology in rats with intracerebral hemorrhage / 国际脑血管病杂志

Objecthe To equate the effects of recombinant human growth hormone (rhGH) on serum albumin lewis and intestinal mucosal morphology in rats with intracerebral hemorrhage. Methods A rat model of intracerebral hemorrhage was induced by autologous blood injection. Fifty-six SD rats were divided into sham-operation group (n =8), rhGH group (n =24; intraperitoneal injection of rhGH, 1 U/kg, once a day), and saline control group (n =24; intraperitoneal injection of equivalent normal saline, once a day). The rhGH and saline control groups were redivided into 1-, 7- and 14-day groups (n =8 in each group) after the procedure. The serum albumin concentration was detected at different time points in all groups. The changes of intestinal mucosal morphology were observed with Hematoxylin and Eosin (HE)staining and image analysis. Results Hie serum albumin lewis at all time points of intracerebral hemorrhage in the saline control group were all significantly lower than those in the sham-operation group (all P < 0. 01); The serum albumin level was increased gradually with the treatment process in the rhGH group, however, it was only significantly higher than the saline control group at day 14 (39.93 ±1.98 g/L νs. 37. 93 ±1.57 g/L) (P<0. 01). There were no significant differences between the rhGH group and the saline group in intestinal villus height and mucosal thickness at day 1 and 7 after intracerebral hemorrhage, however they were increased significantly at day 14 (P <0.01). The area of intestinal villi was reduced progressively at day 1, 7 and 14 after intracerebral hemorrhage, and with the treatment process the rhGH group was increased more progressively than the saline control group (P <0. 01). The depth of intestinal glands in the rhGH group was increased significantly than that in the saline control group (P <0. 01), but there was no significant difference at day 14; the density of glands in the rhGH group was significantly increased than that in the saline group at day 1 after intracerebral hemorrhage (P < 0. 01), and it was not increased significantly at day 7, however, it was not increased but decreased slightly at day 14. Conclusions The serum albumin level in rats with intracerebral hemorrhage was decreased significantly than that in the sham-operation group, and intracerebral hemorrhage could cause intestinal mucosal injury. rhGH increased the serum albumin level in rats with intracerebral hemorrhage. It might reduce intestinal mucosal injury to different degrees whether it was in the early or late intracerebral hemorrhage, and the late improvement was more significant. The improvement degree of rhGH on intestinal mucosal injury was positively correlated with the increased degrees of the serum albumin level.