Turnover of Brain Monoamine Oxidase Measured In Vivo by Positron Emission Tomography Using l-[11C]Deprenyl

The distribution of carbon-11-labeled L-deprenyl, an irreversible inhibitor of monoamine oxidase type B (MAO-B), was determined in the baboon brain by positron emission tomography. The irreversible blood-to-brain transfer constant (influx constant, K_i) was measured using a complete metabolite-corrected arterial plasma concentration curve. This influx constant was used as a measure of functional enzyme activity for sequential determinations of MAO-B recovery following a single high dose of unlabeled l -deprenyl. The half-life for turnover of MAO-B was thus determined to be 30 days. Using appropriate irreversible inhibitors, this procedure should be generally useful for determining enzyme turnover rates in any organ in vivo and can be applied to some human studies as well.     

Comparison of Three 18F-Labeled Butyrophenone Neuroleptic Drugs in the Baboon Using Positron Emission Tomography

The butyrophenone neuroleptics spiroperidol, benperidol, and haloperidol were radiolabeled with fluorine-18 and studied in baboon brain using positron emission transaxial tomography (PETT). Pretreatment of the baboon with a high pharmacological dose of (+)-butaclamol reduced the specifically bound component of radioactivity distribution in the striatum to approximately the radioactivity distribution found in the cerebellum. Comparative studies of brain distribution kinetics over a 4-h period indicated that either [18F]spiroperidol or [18F]benperidol may be suitable for specific labeling of neuroleptic receptors. In an 8-h study with [18F]spiroperidol, striatal radioactivity did not decline, suggesting that spiroperidol either has a very slow dissociation rate or that it binds irreversibly to these receptors in vivo. [18F]Haloperidol may not be suitable for in vivo PETT studies, because of a relatively high component of nonspecific distribution and a faster dissociation from the receptor. Analysis of 18F in plasma after injection of [18F]spiroperidol indicated rapid metabolism to polar and acidic metabolites, with only 40% of the total radioactivity being present as unchanged drug after 30 min. Analysis of the metabolic stability of the radioactively labeled compound in rat striatum indicated that greater than 95% of [18F]spiroperidol remains unchanged after 4 h.     

In Vitro Studies on the Antiviral Activity of 1,3-Bis(2-Chloroethyl)-1-Nitrosourea

Chemotherapy experiments carried out in vitro demonstrated that 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) was active against lymphocytic choriomeningitis virus and had an equivocal antiviral effect on Semliki Forest, herpes simplex, and vaccinia viruses. No antiviral effect was observed with BCNU against western equine encephalomyelitis, polio, and parainfluenza (HA-1) viruses. Activity of the drug was determined by inhibition of viral-induced cytopathogenic effect in KB or chick embryo cells and by reduction of virus titer in cell culture supernatant fluid. Maximal activity against the viruses was observed when drug and virus were incubated together for 30 min prior to addition to cells; essentially no activity could be demonstrated if BCNU and virus were added to cells with no prior incubation.     

蚕豆叶片发育与衰老过程中超氧物歧化酶活性与丙二醛含量变化

蚕豆植株叶片随茎节自上而下表现出明显的发育与衰老顺序,可作为衰老特征的是叶绿素和蛋白质含量明显下降。蚕豆叶中SOD活性主要定位于12 000× g离心后所得的上清液和叶绿体组分。衰老叶片的SOD总活性和叶绿体组分的相对活性都有所下降,SOD同工酶谱也发生了改变。O_2~ 产生速率随叶龄增大而稍上升;而MDA含量在叶片外观表现枯黄衰老征兆前就急剧上升。可能因为衰老叶片过氧化氢酶活性大幅度下降与SOD之间的不平衡,致使O_2~ 代谢中间产物累积而引起膜的损伤.     

Biosynthesis of lysosomal hydrolases: their synthesis in bound polysomes and the role of co- and post-translational processing in determining their subcellular distribution

By in vitro translation of mRNA’s isolated from free and membrane-bound polysomes, direct evidence was obtained for the synthesis of two lysosomal hydrolases, β-glucuronidase of the rat preputial gland and cathespin D of mouse spleen, on polysomes bound to rough endoplasmic reticulum (ER) membranes. When the mRNA’s for these two proteins were translated in the presence of microsomal membranes, the in vitro synthesized polypeptides were cotranslationally glycosylated and transferred into the microsomal lumen. Polypeptides synthesized in the absence of microsomal membranes were approximately 2,000 daltons larger than the respective unglycosylated microsomal polypeptides found after short times of labeling in cultured rat liver cells treated with tunicamycin. This strongly suggests that nascent chains of the lysosomal enzymes bear transient amino terminal signals which determine synthesis on bound polysomes and are removed during the cotranslational insertion of the polypeptides into the ER membranes. In the line of cultured rat liver cells used for this work, newly synthesized lysosomal hydrolases showed a dual destination; approximately 60 percent of the microsomal polypeptides detected after short times of labeling were subsequently processed proteolytically to lower molecular weight forms characteristic of the mature enzymes. The remainder was secreted from the cells without further proteolytic processing. As previously observed by other investigations in cultured fibroblasts (A. Gonzalez-Noriega, J.H. Grubbs, V. Talkad, and W.S. Sly, 1980, J Cell Biol. 85: 839-852; A. Hasilik and E.F. Neufeld, 1980, J. Biol. Chem., 255:4937-4945.) the lysosomotropic amine chloroquine prevented the proteolytic maturation of newly synthesized hydrolases and enhanced their section. In addition, unglycosylated hydrolases synthesized in cells treated with tunicamycin were exclusively exported from the cells without undergoing proteolytic processing. These results support the notions that modified sugar residues serve as sorting out signals which address the hydrolases to their lysosomal destination and that final proteolytic cleavage of hydrolase precursors take place within lysosome itself. Structural differences in the carbohydrate chains of intracellular and secreted precursors of cathespin D were detected from their differential sensitivity to digestion with endoglycosidases H and D. These observations suggest that the hydrolases exported into the medium follow the normal secretory route and that some of their oligosaccharides are subject to modifications known to affect many secretory glycoproteins during their passage through the Golgi apparatus.     

Immigrant Civic Engagement: New Translations

This study used a mixed methods methodology to investigate the reliability and validity of the Ounce Scale, an authentic, observational assessment of infants' and toddlers' development from birth through 42 months of age. Quantitative cross-sectional data were collected from 287 children and 124 teachers in seven urban Early Head Start programs; qualitative data were derived from interviews with 21 teachers and seven supervisors. Data were collected across eight age groups. Results showed moderate reliability of the Ounce Scale and provided evidence of agreement with criterion measures for concurrent validity. Receiver operating characteristic curve (ROC) analyses demonstrated very good levels of accuracy in predicting which children were at-risk or not at-risk. Hierarchical regression analyses indicated that, after controlling for child and family variables, the Ounce Scale contributed significantly to explaining the variance in children's performance on the criterion measures. Analysis of qualitative interview data elaborates on these findings in terms of the strength-based philosophy of the caregivers, the binary structure of the scale, the cultural context in which the scale was used, and the need for additional professional development. Discussion also centers on the relationship between norm-referenced and performance-based assessments in early childhood.     

Immigrants' Cultural Identities as Sources of Civic Engagement

Immigrant parents (first generation) and adolescents (second generation) from El Salvador and India (N = 80) took part in interviews on civic engagement. The immigrants were almost unanimous in regarding civic engagement as important. They also were engaged themselves, more so at the community than the political level. One third of immigrants were engaged in community activities that specifically had a cultural focus or occurred through cultural organizations, and the comparable number for political activities was 25%. Cultural motives (i.e., a cultural or immigrant sense of self) were twice as likely to be mentioned as sources of engagement rather than disengagement. Qualitative analyses of these cultural motives revealed seven engagement themes (e.g., cultural tradition of service) and three of disengagement (e.g., ethnic exclusion).     

Right Bundle Branch Block: A Predictor of Mortality in Early Systemic Sclerosis

Objective

To evaluate the prognostic significance of baseline electrocardiogram (ECG) abnormalities in a multiethnic cohort of patients with early systemic sclerosis (SSc) and to determine the serological, clinical, and echocardiogram correlates of ECG findings.

Methods

SSc patients with disease duration of≤5 years were enrolled in the GENISOS (Genetics versus Environment in Scleroderma Outcome Study) cohort. At the first visit, a standard 12 lead ECG was obtained along with demographic information, clinical data, and autoantibodies. The results of echocardiograms were also recorded. All ECGs were interpreted by a cardiologist unaware of the patients'' clinical data.

Results

Of 265 SSc patients with average disease duration at enrollment of 2.5 years, 140 (52.8%) had abnormal ECG findings. These findings were not associated with SSc disease type or autoantibody profile but were associated with more severe heart and lung involvement. A total of 75 patients (28.3%) died over a follow up time of 9.9 years. Complete right bundle branch block (± left anterior hemiblock) on ECG, present in 7 (2.6%) patients, predicted a higher risk of mortality (HR: 5.3; 95% CI: 2.1 to 13.4; p<0.001). The predictive significance of right bundle branch block was independent of age at enrollment, gender, ethnicity and risk factors for coronary artery disease.

Conclusion

ECG abnormalities are common in patients with early SSc and are associated with the severity of lung and heart involvement. Right bundle branch block is an independent predictor of mortality, and should be considered a marker of disease severity in SSc.     

Association of DNA Methylation at CPT1A Locus with Metabolic Syndrome in the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN) Study

In this study, we conducted an epigenome-wide association study of metabolic syndrome (MetS) among 846 participants of European descent in the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN). DNA was isolated from CD4+ T cells and methylation at ~470,000 cytosine-phosphate-guanine dinucleotide (CpG) pairs was assayed using the Illumina Infinium HumanMethylation450 BeadChip. We modeled the percentage methylation at individual CpGs as a function of MetS using linear mixed models. A Bonferroni-corrected P-value of 1.1 x 10⁻⁷ was considered significant. Methylation at two CpG sites in CPT1A on chromosome 11 was significantly associated with MetS (P for cg00574958 = 2.6x10^-14 and P for cg17058475 = 1.2x10^-9). Significant associations were replicated in both European and African ancestry participants of the Bogalusa Heart Study. Our findings suggest that methylation in CPT1A is a promising epigenetic marker for MetS risk which could become useful as a treatment target in the future.