The effects of several aminopeptidases towards thionopeptides.
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Aminopeptidases↗
Biomedical subjects
S L Martin
Publications and source records attributed to S L Martin.
Developmental and cell type specificity of LINE-1 expression in mouse testis: implications for transposition.
The LINE-1, or L1, family of interspersed repeated DNA constitutes roughly 10% of the mammalian genome. Its abundance is due to duplicative transposition via an RNA intermediate, L1-encoded proteins, and reverse transcription. Although, in principle, transposition may occur in any cell type, expression and transposition of a full-length functional element in the germ line are necessary to explain the evolutionary genetics of L1. We have found differential expression of L1 protein and RNA in germ and somatic cells of the mouse testis during development. Of particular interest is the coexpression of full-length, sense-strand L1 RNA and L1-encoded protein in leptotene and zygotene spermatocytes at postnatal day 14 of development. Expression in meiotic prophase precedes the strand breakage that occurs during chromosomal recombination; this offers an avenue for L1 insertion into new locations in chromosomal DNA in a cell type that ensures L1 propagation in future generations.
Aging↗
Aggression and fighting behavior among African-American adolescents: individual and family factors.
OBJECTIVES: This study examined the extent to which individual and family factors are associated with aggression and fighting behavior among African-American middle school adolescents. METHODS: Four hundred thirty-six African-American boys and girls from two middle schools in a predominantly low-income North Carolina school system were surveyed and their school records examined. Information was collected concerning students' aggression levels, school fighting behavior, school suspensions for fighting, attitudes toward violence, perceptions of their families' attitudes toward violence, weapon-carrying behavior, and sociodemographics. Multivariate analyses were employed to predict the students' aggression levels, fighting behavior, and school suspensions. RESULTS: Factors related to the individual adolescents, such as gender, age, weapon-carrying behavior, and attitudes toward violence, were associated with students' reports of aggression and fighting behavior. Factors related to family and school were associated with school suspension for fighting. CONCLUSIONS: This study suggests that violence prevention programs set in our elementary and middle schools may reduce aggression and fighting among our youth. School teachers and public health practitioners are encouraged to work together in understanding and preventing adolescent violence.
Adolescent↗
Echocardiographic evaluation of anuloplasty rings. Comparison of continuity equation and pressure half-time methods.
This study was undertaken to compare pressure half-time and continuity equation methods in the postoperative evaluation of anuloplasty rings. We performed 2-dimensional echocardiography and Doppler studies in 39 patients who had undergone valve repair for mitral regurgitation. In patients with a pressure half-time of 110 msec or more (9/39), there was no significant difference in calculated valve area between the 2 methods (p = 0.696). A significant difference was shown between the 2 methods (p < 0.001) in patients with a half-time less than 110 msec (30/39). When patients were classified according to the type of ring they had received, no significant difference was noted between the 2 groups with regard to peak and mean mitral gradients. In patients placed in subgroups according to half-times of less than 110 msec and half-times of 110 msec or more, no difference was noted between groups in terms of mean mitral gradient, presence of mitral regurgitation, left atrial size, left ventricular function, or heart rate. The continuity equation appears to provide much more homogeneous results in the calculation of valve area in patients who have undergone valvular repair for mitral valve regurgitation.
Adolescent↗
A recent origin of marmots.
The complete mitochondrial cytochrome b genes from four ground squirrels, a marmot, and a tree squirrel were sequenced and compared. A level of divergence three times lower than expected based on fossil evidence was found between the marmot and the ground squirrels. The observed divergence was similar to that found within the ground squirrels and is consistent with a recent divergence of marmots (Marmota) from true ground squirrels (Spermophilus).
Animals↗
Molecular approaches to mammalian retrotransposon isolation.
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Amino Acid Sequence↗
Synchronous expression of LINE-1 RNA and protein in mouse embryonal carcinoma cells.
L1, or LINE-1, is a repetitive DNA family found in all mammalian genomes that have been examined. At least a few individual members of the L1 family are functional transposable elements. Expression of these active elements leads to new insertions of L1 into the genomic DNA by the process of retrotransposition. We have detected coexpression of full-length, sense-strand L1 RNA transcripts and L1-encoded protein in mouse embryonal carcinoma cell lines. Both of these L1 expression products are candidates for intermediates in the retrotransposition process. L1 protein is found in what appear to be cytoplasmic aggregates and is not localized to any known cytoplasmic organelles. The six embryonal carcinoma cell lines tested were chosen to represent commitment to different developmental pathways in early mouse embryogenesis. The only two cell lines that express L1 are unique among the six in that they have a strong predilection to differentiate into extraembryonic endoderm. This observation is consistent with L1 expression and transposition in primordial germ cells of the mouse. An important implication of these studies is that L1 expression may provide a new marker for use in determining the origin of primordial germ cells during mouse embryogenesis.
Animals↗
Capillary filtration coefficients using laser densitometry and gravimetry in isolated dog lungs.
We compared pulmonary capillary filtration coefficients (Kf,c) using measurements of transcapillary filtration rates based on laser densitometry of perfusate hematocrit changes (Jy,l) and gravimetric measurement of the rate of lobe weight gain (delta Wt/delta t) after an increase in capillary pressure (Pc) in isolated autologous blood-perfused dog lungs. Although the lobe weight increased at a rate that decreased with time, the densitometric filtration rate was relatively constant over time. Kf,c values were calculated in milliliters per minute per centimeter water per 100 g from filtration rates obtained by 1) extrapolation of the delta Wt/delta t from 3 to 10 min back to time 0 [Kf,c(0)], 2) use of the slope of the line fitted to the delta Wt/delta t and Jv,l values obtained after three stepwise increases in Pc [Kf,c(slope)], and 3) use of delta Wt/delta t and Jv,l values obtained 10, 20, and 30 min after either a constant 30-min or three 10-min stepwise increases in Pc [Kf,c(t)]. The mean Kf,c(0) values ranged from 0.171 +/- 0.024 to 0.188 +/- 0.070 and were not significantly different between vascular pressure states. These Kf,c(0) values were significantly higher than all gravimetric or densitometric Kf,c(t) or Kf,c(slope) values that ranged from 0.037 to 0.100. Kf,c(t) values were not statistically different from each other by use of either method, but the gravimetric Kf,c(slope) was significantly higher than the densitometric value. Therefore, extrapolated Kf,c(0) probably overestimates endothelial barrier Kf,c because of persistent vascular stress relaxation after a vascular pressure increase. Adjustment of tissue Starling forces may occur rapidly after an increase in filtration pressure.
Animals↗
Central role for differential gene expression in mammalian hibernation.
Mammalian hibernators experience dramatic reductions in body temperature, metabolic rate, respiratory rate, and heart rate during hibernation. These changes are precisely controlled and reversible with only internally driven mechanisms, suggesting specific biochemical regulation. We present a model that integrates our observations of differential liver gene expression during preparation for, and maintenance of, the hibernating state, with the known phylogenetic interspersion of hibernating species in several major mammalian lineages. This model predicts a major role for the differential expression of existing mammalian genes in the biochemical regulation of hibernation.
Animals↗
The mental health of incarcerated women.
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Adult↗
Young women's antisocial behavior and the later emotional and behavioral health of their children.
OBJECTIVES: Antisocial and criminal behavior are increasing among US youth, especially among females. Thus, questions arise concerning whether youthful female deviant behavior eventually will have negative behavioral and emotional consequences for the later children of these women. METHODS: Associations between the severity of early female antisocial behavior (including both drug-related and non-drug related offenses) and the later behavioral and emotional health of the children of these women were examined among 1425 mother-child pairs of the National Longitudinal Survey of Youth. RESULTS: Multiple linear regression procedures indicated a significant positive relationship between the severity of the mothers' early non-drug-related offenses and the later severity of the children's scores on the Antisocial, Hyperactive, Anxious/Depressed, Headstrong, Peer Conflict/Social Withdrawal, Immature Dependency, and Total Problem subscales of the Behavior Problem Index. CONCLUSIONS: This study demonstrated an association between the antisocial behavior of female youth and the later behavioral and emotional problems of the children of these women. Future research needs to determine the mechanisms underlying the intergenerational transmission of these types of problems so that effective preventive and therapeutic public health practices may be designed and implemented.
Adolescent↗
LINEs.
LINEs are ubiquitous transposable elements of eukaryotes. Significant information has accumulated in the past year concerning the mechanism of transposition and the intermediates involved. In addition, progress has been made in the understanding of LINE structure and evolution, and several laboratories have exploited the interspersed, repetitive nature of LINEs for use in genome mapping.
Animals↗
Site-specific forced misincorporation mutagenesis using modified T7 DNA polymerase.
A new method for forced misincorporation site-specific mutagenesis is described. The method uses an exonuclease-deficient modified version of T7 DNA polymerase in the presence of one dNTP to force a misincorporation. Analysis by PAGE is used to monitor the efficiency of such misincorporation reactions. Brief extension of the terminally mismatched primer/template using the same enzyme in the presence of all four dNTPs is followed by chase/ligation using unmodified T7 DNA polymerase and T4 DNA ligase to give heteroduplex DNA. We have applied the method to mutagenesis of the Lac Z region of M13 and found that, using strand selection, efficiencies of mutagenesis at one site are greater than 50%. When the mutating dNTP is complementary to a neighbouring homopolymeric tract on the template, multiple mutation is observed and efficiences are lower. The method is more general than internal mismatch mutagenesis and, because of its rapidity, is more expedient than existing methods of forced misincorporation mutagenesis.
Amino Acid Sequence↗
Differential prediction of young adult arrests for property and personal crimes: findings of a cohort follow-up study of violent boys from North Carolina's Willie M Program.
Which characteristics of violent youth predict adult arrest for property crimes (e.g. burglary), and for personal crimes (e.g. assault)? We addressed this question by focusing on a group of particularly violent and assaultive boys. Separate logistic regression analyses were conducted to predict property and personal crime arrests as a function of adolescent psychiatric diagnosis, behavior problem history, race and IQ. Property crime arrest was predicted by an adolescent history of property offenses, conduct disorder diagnosis, and race (more arrests among non-whites than whites). Personal crime arrest was predicted by adolescent history of property offenses and adolescent history of substance abuse.
Adolescent↗
Ribonucleoprotein particles with LINE-1 RNA in mouse embryonal carcinoma cells.
The LINE-1 repeat family is interspersed throughout mammalian genomes and is thought to be the result of duplicative transposition of LINE-1 sequences via an RNA intermediate. This report describes a ribonucleoprotein particle with LINE-1 RNA in the mouse embryonal carcinoma cell line F9. This ribonucleoprotein particle is a potential intermediate in the transposition of LINE-1 in the mouse genome.
Animals↗
The prevention of intellectual impairment in children of impoverished families: findings of a randomized trial of educational day care.
We estimated the effects of an experimental educational day care program on the intellectual development of preschoolers from 86 high-risk families in a randomly allocated longitudinal study. At six through 54 months of age, the IQs of experimental program children ranged from 7.9 to 20.1 points higher than those of control children when maternal mental retardation and home environment effects were controlled; at every age, a greater proportion of the experimental program children had normal range IQs (greater than 84). In 13 children with retarded mothers, none of six experimental program children, but six of seven control children, had IQ scores below normal.
Adult↗
A multidimensional approach for selecting child care workers.
A multidimensional selection battery was designed to predict a variety of criteria important in the selection of child care workers. The battery assesses constructs related to honesty, violence, substance abuse, emotional stability and safety. A series of studies were used to test the validity of the selection battery. Scores on the test battery were compared with those from three alternative selection procedures to define the measured constructs. Three additional studies show the relation of scores on the selection battery and the behavior of child care workers. The test battery was correlated with the job performance of child care workers and identified adults convicted for sexual offenses against minors.
Adult↗
A conserved open reading frame that overlaps the herpes simplex virus thymidine kinase gene is important for viral growth in cell culture.
Of 18 mutants containing clustered point mutations within UL24 (an open reading frame that overlaps the herpes simplex virus thymidine kinase gene on the opposite strand), 15 formed small plaques and were substantially impaired for virus growth in cell culture. Mutations conferring the small plaque phenotype disrupt regions of UL24 that share considerable sequence similarity with open reading frames common to herpesviruses of mammals and birds. We infer that UL24 is expressed and important for virus growth in cell culture and suggest that possible effects on UL24 should be considered in studies of thymidine kinase-deficient mutants.
Amino Acid Sequence↗