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PubMed1999

Communication about sexual issues: mothers, fathers, and friends.

PURPOSE: To identify the content, characteristics, and comfort level of discussions about sexuality held between mothers and their early adolescent children and to determine the extent to which the conversations predicted sexual values and initiation of sexual intercourse of the adolescent. METHODS: This was part of a larger study to evaluate the impact of personal family characteristics on human immunodeficiency virus risk-reduction behavior among low-income predominately African-American adolescents, ages 13-15 years. Adolescents attending a metropolitan community-based afterschool program and their mothers were invited to participate in a 1-hour interview. Mothers and adolescents were interviewed separately. The interview included questions about the type of information related to sexuality that adolescents discussed with mothers, fathers, and friends; in addition, mothers were asked what topics they discussed with their adolescents. Four hundred five adolescents and 382 mothers participated. Some mothers had more than one adolescent in the study. RESULTS: The results showed that both male and female adolescents were more likely to discuss sexual topics with their mothers than their fathers. Male adolescents were more likely than female adolescents to discuss sex-based topics with their fathers. Both male and female adolescents were less likely to discuss sex-based topics with their friends than with their mothers, but more likely to discuss these topics with their friends than their fathers. Content of conversations of male adolescents was fairly consistent among mothers, fathers, and friends, and sexually transmitted disease/acquired immune deficiency syndrome and condom use were popular topics of discussion. Female adolescents tended to talk about the menstrual cycle with their mothers, sexual abstinence with their fathers, and sexual intercourse with their friends. Adolescents who reported a greater number of topics discussed with their mothers were more likely not to have initiated sexual intercourse and to have conservative values, whereas adolescents who reported a greater number of topics discussed with their friends were more likely to report the initiation of intercourse and more "liberal" sexual values. Both male and female adolescents were most comfortable discussing sexual issues with their friends. Male adolescents were less comfortable talking to mothers, but more comfortable talking to their fathers than were females. Mothers were likely to report feeling very comfortable talking about almost all discussion areas. Fathers' comfort level was not measured, as they were not directly questioned. CONCLUSION: Early adolescence (13-15 years old) is characterized by more sex-based discussions with mothers than friends or fathers. Daughters and sons discuss different topics with their fathers, although discussion by both genders with fathers is limited. If an adolescent talks more with the mother about sexual issues than with friends, he/she is less likely to initiate sexual intercourse and more likely to have conservative values. This points to the importance of fostering good communication and comfort between parents and adolescents about sexual issues.

Adolescent↗
PubMed2005

Alcohol use in early adolescence: the effect of changes in risk taking, perceived harm and friends' alcohol use.

OBJECTIVE: Friends' substance use, sensation seeking and low perceived harm are well-established risk factors for substance use, but they are often treated as stable factors that affect adolescents' likelihood of substance use. This study instead explores the effects of changes in risk factors for individual adolescents. METHOD: Participants in this study were 1,065 male and female students. The students were in sixth or seventh grade at the initial survey and provided survey data on three additional occasions over a period of 2 years. Random-coefficient models were used to assess the intraindividual variability of friends' alcohol use, perceived harm, and risk taking and their effect on alcohol use. RESULTS: As expected, the overall number of alcohol-using friends is correlated with a student's own alcohol use. In addition, there is a dynamic relationship within student; as friends' alcohol use changes over time, it is accompanied by parallel changes in alcohol use by the individual. Two moderating variables of the effect of friends' use of alcohol were validated: perceived harm of alcohol use and risk taking. The effect of increased exposure to alcohol-using friends is more robust during times when an adolescent also has become less likely to perceive the harmful effects of alcohol use or when an adolescent indicates increased interest in risk-taking behavior. CONCLUSIONS: Although friends' use of alcohol is a salient predictor of an adolescent's own use of alcohol, some types of students are more likely than others to be influenced by friends' behavior, In particular, students' perception of harm and predisposition to risk taking are important moderators of the effect of friends' influence.

Adolescent↗
PubMed1993

[Actions of physicians, nurses, parents and friends in relationship with young diabetic patients].

The purpose of this study was to use young diabetics descriptions of their illness, treatment and care to explain the actions of physicians, nurses, parents and friends relationship with diabetics'. The empirical data were collected by interviewing 51 diabetics of age 13-17-years. The data were processed by the method of continuous comparative analysis. The young diabetics described the actions of physicians as motivating, authoritarian, negligent and routine. By motivating they meant that, the doctors and young diabetics acted together, discussing the treatment and care and planning it together, whereas the routine and authoritarian aspects of their action referred to things that the doctors didn't discuss with the patient, and care that wasn't individual. The nurses' were described as taking notice of the young diabetics as individuals, but their actions were or intended to comply with the doctors' instructions. The individual aspect consisted of planning the care together and trying to combine it with the young persons's life. The actions of the parents were described as motivating, involving acceptance and disciplined control. Their motivating action consisted of support and a natural interest in young diabetics's life and not only in the disease. The parents who accepted the young diabetics didn't try to influence them. They accepted that the people would not necessarily care for themselves. Their disciplined control consisted of a lot of questions about care and attempts to oblige the young diabetics to care for themselves better than they do. The young diabetics described their interaction with friends, in terms of their silent support, their friends dominating their lives or their friends having no meaning for their self care. When their friends dominated their lives, the young diabetics lived according to their friends' habit, in which case the care didn't fit in with the young diabetics' life style. The silent support of the friends was typical in that the friends reminded the young diabetics of their care and tried to change their own habits to fit the young diabetics' lives. Friends had no meaning for those young diabetics for whom the care was a natural part of their lives.

Adolescent↗
PubMed1997

Disruptiveness, friends' characteristics, and delinquency in early adolescence: a test of two competing models of development.

This study tested 2 competing models of friends' influence on the development of delinquency in disruptive boys. In so doing, we examined whether highly disruptive, moderately disruptive, moderately conforming, and highly conforming boys' delinquency increased or decreased depending on their friends' characteristics. A sample of 868 boys was classified into the 4 groups according to teacher ratings at ages 11 and 12. Each group was then subdivided by mutual friends' peer-rated aggressiveness-disturbance at the same ages: aggressive-disturbing friends, average friends, nonaggressive-nondisturbing friends, and no friends. Subgroups were next compared on self-reported delinquency at age 13 while controlling for average self-reported delinquency and socioeconomic variables at ages 11 and 12. Results indicate that moderately disruptive boys with aggressive-disturbing friends were more delinquent at age 13 than other subgroups of moderately disruptive boys. Highly disruptive and conforming boys, however, were unaffected by their friends' characteristics. We conclude that the results partially support each theoretical model, suggesting that both individual characteristics and deviant peer association might play causal roles.

Adolescent↗
PubMed1998

[Family and friends who smoke: influence on adolescents].

BACKGROUND: Smoking is the leading preventable cause of death. Most cigarette smokers take up the habit during adolescence. The purpose of this study was to assess the prevalence of cigarette smoking behavior among the students of a metropolitan high school as compared to those attending a non-metropolitan high school, examining age, sex and demographic and socioeconomic differences, as well as the influence of smoking models (family members and friends) on smoking behavior among adolescents. METHODS AND RESULTS: Nine hundred seventy-eight students (544 males, 434 females; mean age 15.8 +/- 1.5 years) attending a high school in the city of Naples and 467 students (235 males, 232 females; mean age 16 +/- 1.5 years) from a high school of Capua, a small town 40 kilometers away from Naples, filled out an extensive questionnaire on smoking. The prevalence of smokers was 24.2% (males 21.8%, females 28.2%; p = 0.02) in Naples and 23.8% in Capua (males 29.8%, females 19.2%; p < 0.001) and was related to age (p < 0.001) both in Naples and in Capua. In Naples, smoking behavior among male students was associated with smoking by sibling (p = 0.00005), whereas an association with father (p = 0.0003), mother (p = 0.00005), parental (p = 0.0002) and sibling (p = 0.00002) smoking was observed among females. In Capua, an association was evident only between smoking in female students and sibling smoking habits (p = 0.02). In both Naples and Capua, smoking status of the students was related to smoking habits of best friends of the same sex, best friends of the opposite sex and friends. Multivariate analysis showed an independent relationship in Naples between adolescent smoking behavior and smoking status of siblings (p = 0.01), best friends of the same sex (p < 0.001) and best friends of the opposite sex (p < 0.001). In males, smoking behavior was associated with the smoking behavior of best friends of the same (p < 0.001) and of the opposite sex (p = 0.01), whereas in females, it was linked with the smoking behavior of siblings (p = 0.05), mother (p < 0.05) and best friends of the same sex (p < 0.001). In Capua, student smoking was related to smoking among friends (p < 0.001) and this held true for both males (p = 0.05) and females (p < 0.0001). CONCLUSIONS: The prevalence of smoking habits among teenagers is similar in two distinct populations of high school students from a city and from a small town. Smoking showed a higher prevalence among females in the city and among males in the small town. It increases with age and is related to peer and family smoking models. This study has identified several variables associated with smoking status among adolescents. We thus feel that these findings may contribute to a better understanding of smoking behavior among teenagers and may have prevention implications.

Adolescent↗
PubMed1979

Comparison of chloride transport in mouse erythrocytes and Friend virus-transformed erythroleukemic cells.

Friend erythroleukemic cells, which grow continuously in tissue culture, resemble in many respects early precursors of mouse erythrocytes. To determine whether or not the membranes of these cells exhibit the rapid and selective exchange of chloride, a specialized feature of the mature erythrocyte membrane, anion fluxes were compared in Friend cells and mouse erythrocytes. The chloride flux in Friend cells at 37 degrees C was about 800-fold lower than in mouse erythrocytes (extrapolated from data at lower temperatures). This difference could not be accounted for by the somewhat lower chloride concentration in Friend cells relative to erythrocytes. Comparison of chloride and sulfate fluxes revealed that the Friend cells had over a 1,000-fold lower selectivity for chloride versus sulphate than did the mouse red cells. The temperature dependence of chloride fluxes in Friend cells corresponded to an Arrhenius activation energy of 17.9 kcal/mol, in contrast to over 30 kcal/mol for mature red cells. The chloride flux in Friend cells was also 10-fold less sensitive to the inhibitor, furosemide, than was the flux in mature red cells. The selective chloride exchange system of the mature erythrocyte therefore does not seem to be functional at the stage represented by the Friend cell, and must appear at some later stage of erythroid maturation.

Animals↗
PubMed2005

Resistance to friend virus-induced erythroleukemia in W/W(v) mice is caused by a spleen-specific defect which results in a severe reduction in target cells and a lack of Sf-Stk expression.

The characteristic progression and specificity of Friend virus for the erythroid lineage have allowed for the identification of a number of host-encoded loci that are required for disease progression. Several of these loci, including the Friend virus susceptibility gene 2 (Fv2), dominant white spotting gene (W), and Steel gene (Sl), regulate the initial polyclonal expansion of infected erythroid progenitor cells. W and Sl encode the Kit receptor tyrosine kinase and its ligand, stem cell factor, respectively. W mutant mice are severely anemic, and earlier work suggested that this defect in erythroid differentiation is the cause for the resistance to Friend virus-induced erythroleukemia. Here we show that in bone marrow, W/W(v) mice have near normal numbers of target cells and the initial infection of bone marrow occurs normally in vivo. In contrast, spleen cells from W/W(v) mice infected both in vitro and in vivo with Friend virus failed to give rise to erythropoietin-independent colonies at any time following Friend virus infection, suggesting that mutation of the Kit receptor specifically affects target cells in the spleen, rendering the mutant mice resistant to the development of Friend virus-induced erythroleukemia. In addition, we show that the Kit+ pathogenic targets of Friend virus in the spleen are distinct from the pathogenic targets in bone marrow and this population of spleen target cells is markedly decreased in W/W(v) mice and these cells fail to express Sf-Stk. These results also underscore the unique nature of the spleen microenvironment in its role in supporting the progression of acute leukemia in Friend virus-infected mice.

Animals↗
PubMed2006

Friends' influence on adolescents' first sexual intercourse.

CONTEXT: Social-psychological theories of health behavior suggest that adolescents' sexual behaviors are influenced by the sexual attitudes and behaviors of their friends. METHODS: Data on 2,436 participants in the National Longitudinal Study of Adolescent Health (Add Health) who were sexually inexperienced at Wave 1 (1994-1995) were analyzed to examine whether friend-related variables predicted initiation of vaginal intercourse by Wave 2 (1996). Analyses also assessed whether predictive relationships varied by level of involvement with friends. Odds ratios were generated by logistic regression analysis. RESULTS: In the 9-18 months between Waves 1 and 2, 18% of participants initiated intercourse. In analyses controlling for gender, family structure and romantic relationships, the higher the proportion of a youth's friends who were sexually experienced, the greater the odds of sexual debut (odds ratio, 1.01); the odds also were elevated among youth who believed that they would gain their friends' respect by having sex (1.2). Relationships between friend variables and sexual initiation did not vary by level of involvement with friends. CONCLUSIONS: To maximize the likelihood of success, programs focused on delaying teenage sexual intercourse should address norms for sexual behavior among adolescents' close friends as well as the perceptions, skills and behaviors of individual youth.

Adolescent↗
PubMed1984

[Molecular mechanism of erythroid differentiation in mouse Friend cells].

The mechanism of in vitro erythroid differentiation in mouse Friend cells was studied by employing cell fusion between two genetically marked Friend cells and other nonerythroid cells. Erythroid differentiation was induced indirectly by fusing Friend cells that had been exposed briefly to dimethyl sulfoxide prior to fusion with nonerythroid cells that had been treated with ultraviolet light(or other DNA-damaging agents). The results suggest that two distinct reactions are involved in erythroid differentiation in Friend cells in vitro. One reaction, originating from the damaged DNA (or inhibition of DNA replication as a consequence), exhibits an inducible nature, is nonspecific to Friend cells, and is trans-acting. The other reaction is specific to Friend cells. Evidence that a typical tumor promoter, 12-O-tetradecanoylphorbol 13-acetate, inhibits erythroid differentiation by affecting the latter reaction is also presented. Brief exposure of Friend cells to DMSO was found to induce an early cellular activity required fusion for erythroid differentiation which is detected only by with UV irradiated cells. The induction process of this activity consists of at least two distinct stages. In the first stage, the reaction proceeds without supply of metabolites from the medium and exhibits sensitivity to tumor promoters. The second stage is closed involved with cellular metabolic activity, notably protein synthesis. Under normal conditions, the induced activity is short-lived, suggesting that turnover of the molecules responsible for this activity. There appears to be a signal produced following DMSO pulse which acts as an inducer for this activity. The signal remains active as long as 40 hr when protein synthesis is blocked. When permeabilized Friend cells, which had been briefly treated by DMSO, were exposed to cell-free extracts from UV irradiated cells, a small but significant number of the cells became reactive to benzidine, a characteristic of erythroid differentiation. The activity in the extracts was apparently induced following UV irradiation, reaching a maximum 25 to 30 hr after irradiation. After partial purification, the active factor seems to be a protein with a molecular weight of 35,000 to 40,000.

Animals↗
PubMed1979

The role of heme in the regulation of the late program of Friend cell erythroid differentiation.

The addition of a chemical inducer, such as dimethylsulfoxide (DMSO), to cultures of mouse Friend erythroleukemic cells results in the induction of a number of late erythroid events, including the accumulation of globin mRNA, the inducation of hemoglobin synthesis, the appearance of erythrocyte membrane antigens (EMA), and the cessation of cell division. The experiments presented in this study demonstrate that heme is necessary but not sufficient for the loss of proliferative capacity associated with DMSO-induced Friend cell differentiation, whereas the accumulation of globin mRNA and EMA can occur in the absence of heme synthesis or heme itself. These conclusions were reached by selectively inhibiting heme synthesis in DMSO-treated cells in two independent ways: (i) Inducible cells were treated with 3-amino-1,2,4-triazole (AT), a drug which inhibits the induction of heme synthesis in Friend cells in a dose-dependent manner. Treatment of inducible Friend cells with 1.5% DMSO for five days caused the plating efficiency in methyl cellulose to decrease to 1% of that in untreated cultures. However, treatment of the cells with DMSO plus AT almost totally prevented this decrease in plating efficiency. The addition of exogenous hemin, which alone had no significant effect on plating efficiency, largely reversed the effect of AT in DMSO-treated cells, reducing the plating efficiency to below 5%. In contrast to the marked effects of AT on the proliferative capacity of differentiating Friend cells, the levels of globin mRNA and EMA were only partially decreased in cells treated with DMSO plus AT, compared to cells treated with DMSO alone. (ii) The relationship between heme synthesis, terminal cell division, and the induction of globin mRNA was investigated further through the use of non-inducible Friend cell variant clones. One such non-inducible clone, M18, appears to be a phenotypic analog of inducible cells treated with DMSO plus AT. Clone M18 did not accumulate heme or hemoglobin, as detected by benzidine staining, nor lose its proliferative capacity in response to DMSO. However, globin mRNA was induced by DMSO in this clone. Treatment of clone M18 with DMSO plus hemin overcame the block in hemoglobin accumulation suggesting that M18 has a defect in the induction of heme biosynthesis. In addition, exposure of M18 cells to DMSO plus hemin caused a gradual decrease in plating efficiency which was not due to non-specific toxicity. Prior incubation of M18 cells in DMSO for three to five days was necessary before hemin caused a rapid loss of proliferative capacity. Thus, these results, in agreement with the AT studies on inducible Friend cells and previous studies on the induction of EMA in clone M18, indicate that there may be both heme-dependent and heme-independent events in the program of Friend cell differentiation.

Amitrole↗
PubMed2000

Influence of deviant friends on delinquency: searching for moderator variables.

Three categories of potential moderators of the link between best friend's deviancy and boys' delinquency during early adolescence were investigated: personal (i.e., disruptiveneness profile during childhood, attitude toward delinquency), familial (i.e., parental monitoring, attachment to parents), and social (i.e., characteristics of other friends). Best friend's and other friends' deviancy were assessed during preadolescence through the use of peer ratings. Potential moderators were assessed at the same age period with teacher ratings or self-reports. Finally, delinquent behaviors were assessed at ages 13 and 14, as well as age 10 for control purposes, with self-reports. Results showed that boys' disruptiveness profiles during childhood, attachment to parents, and attitude toward delinquency moderated the link between best friend's deviancy and later delinquent behaviors. Other friends' deviancy and parental monitoring had main effects but no moderating effects. These results help clarify the conditions under which exposure to a deviant best friend can influence boys' delinquent behaviors. They also help to reconcile different theoretical explanations of the role of deviant friends in the development of delinquency.

Adolescent↗
PubMed2003

Parents' and friends' smoking status as predictors of smoking onset: findings from six European countries.

This study assessed the relationship between the smoking behavior of adolescents and the smoking status of their parents and friends among adolescents from six European countries. A longitudinal study collected data from 15 705 adolescents on their own smoking status, and that of their parents, best friend and friends in general. Cross-sectional regression analysis showed that adolescent smoking was most strongly associated with friends' smoking and best friend's smoking, explaining 38% of the variance in the total sample. Longitudinal regression analysis, however, showed that the beta coefficients of the smoking status of the best friend and friends in general were comparable to that of parental smoking. Parental smoking behavior was found to be as predictive of smoking onset after 1 year as friends' smoking status.

Adolescent↗
PubMedDate not supplied

Life in a retirement village: implications for contact with community and village friends.

BACKGROUND: Friends provide acceptance, companionship, emotional support, and are important to mental health. One reason that older adults give for seeking alternative accommodations is to reduce their loneliness and isolation. OBJECTIVE: The purpose of this study was to investigate whether older adults living in a retirement village have varying amounts of contact with friends who live within the retirement village or in the wider community. METHODS: Three hundred and twenty-three independently living residents of 25 retirement village sites were interviewed. Participants were asked a range of open and closed questions about the amount and kind of contact they had with co-resident friends and community-based friends. RESULTS: Residents engaged in several weekly visits with village friends and maintained regular contact with community friends through telephone calls. Few residents engaged in community outings or participated in village activities with either village or community friends. CONCLUSION: The nature of living in close proximity with other people, influences the amount of informal contact they have with friends. For those older individuals who seek alternative accommodation due to isolation or loneliness, re-location to congregate-style accommodation may increase their social contacts and have a positive impact on their well-being.

Aged↗
PubMed1986

Control of heme synthesis during Friend cell differentiation: role of iron and transferrin.

In many types of cells the synthesis of delta-aminolevulinic acid (ALA) limits the rate of heme formation. However, results from our laboratory with reticulocytes suggest that the rate of iron uptake from transferrin (Tf), rather than ALA synthase activity, limits the rate of heme synthesis in erythroid cells. To determine whether changes occur in iron metabolism and the control of heme synthesis during erythroid cell development Friend erythroleukemia cells induced to erythroid differentiation by dimethylsulfoxide (DMSO) were studied. While added ALA stimulated heme synthesis in uninduced Friend cells (suggesting ALA synthase is limiting) it did not do so in induced cells. Therefore the possibility was investigated that, in induced cells, iron uptake from Tf limits and controls heme synthesis. Several aspects of iron metabolism were investigated using the synthetic iron chelator salicylaldehyde isonicotinoyl hydrazone (SIH). Both induced and uninduced Friend cells take up and utilize Fe for heme synthesis directly from Fe-SIH without the involvement of transferrin and transferrin receptors and to a much greater extent than from saturating levels of Fe-Tf (20 microM). Furthermore, in induced Friend cells 100 microM Fe-SIH stimulated 2-14C-glycine incorporation into heme up to 3.6-fold as compared to the incorporation observed with saturating concentrations of Fe-Tf. In contrast, Fe-SIH, even when added in high concentrations, did not stimulate heme synthesis in uninduced Friend cells but was able to do so as early as 24 to 48 h following induction. In addition, contrary to previous results with rabbit reticulocytes, Fe-SIH also stimulated globin synthesis in induced Friend cells above the level seen with saturating concentrations of transferrin. These results indicate that some step(s) in the pathway of iron from extracellular Tf to protoporphyrin, rather than the activity of ALA synthase, limits and controls the overall rate of heme and possibly hemoglobin synthesis in differentiating Friend erythroleukemia cells.

Aminolevulinic Acid↗
PubMed1985

Long terminal repeat of Friend-MCF virus contains the sequence responsible for erythroid leukemia.

Friend-MCF virus induces erythroid leukemia when injected into newborn NFS mice whereas Moloney virus induces T-cell lymphoma. To identify the portion of Friend-MCF virus responsible for erythroid leukemia induction four in vitro recombinant viruses were constructed in which env regions or U3 regions of LTR were reciprocally exchanged between Friend-MCF and Moloney viruses. A FrMCF-Mol (LTR) virus whose genome was derived primarily from Friend-MCF virus together with 621 nucleotides of Moloney virus at its 3' end including the U3 region of LTR was a thymic lymphoma-inducing virus. A Mol-FrMCF (LTR) virus with the genome derived primarily from Moloney virus but 596 nucleotides of Friend-MCF virus information at the same region as FrMCF-Mol (LTR) was an erythroid leukemia-inducing virus. A Mol-FrMCF (env) virus whose genome was derived primarily from Moloney virus but which had 2.3 kbp of Friend MCF at the 3' end of the pol gene including most of the env gene with all of gp70 and the N terminal of p15E was a lymphoid leukemia-inducing mink cell focus-inducing virus. FrMCF-Mol (env) virus whose genome was derived primarily from Friend-MCF virus but had 2.7 kbp of Moloney virus at the same region as Mol-FrMCF (env) virus was an erythroid leukemia-inducing ecotropic virus. The Mol-FrMCF (LTR) and Mol-FrMCF (env) viruses induced mixed leukemia of erythroid and lymphoid cells in some mice.

Animals↗
PubMed2002

Relational and physical victimization within friendships: nobody told me there'd be friends like these.

In past research, relational and physical forms of peer victimization have been identified that have been shown to be significantly associated with social-psychological maladjustment. These forms of victimization, although studied primarily within the group peer context, also occur within dyadic relationships such as friendships. Gender differences in friend victimization and the association between friend victimization and children's social-psychological adjustment were examined. Results showed that boys were more physically victimized by their friends than were girls. Girls were more relationally than physically victimized by their friends. Friend victimization was related to adjustment difficulties for both boys and girls; however, friend physical victimization was particularly related to boys whereas friend relational victimization was particularly related to girls. The implications of these findings for future research and intervention with victimized children are discussed.

Adaptation, Psychological↗
PubMed2003

Friends as reporters of children's and adolescents' depressive symptoms.

Obtaining information from multiple informants is important when assessing youth depression. Past studies have utilized adults' reports of youths' emotional functioning and aggregate reports from classmates but have not considered close friends as reporters of depressive symptoms. This is surprising given the important roles of friends as companions and confidants. This study investigated relations between friend-reported depressive symptoms and youths' self-reports. From a larger sample of fifth-, seventh-, and ninth-grade participants, self-reports and friend reports of depressive symptoms and friend reports of friendship quality were available for a subset of 367 participants. Significant positive relations emerged between friend reports and self-reports of affective depressive symptoms for girls and youth in high-quality friendships. Relations between friend reports and self-reports were stronger for conduct-related than affective depressive symptoms and reached significance for boys as well as for girls and for youth in low-quality friendships as well as for youth in high-quality friendships. Implications for identifying at-risk youth are discussed.

Adolescent↗
PubMed2001

Loss of p53 tumor suppressor function is required for in vivo progression of Friend erythroleukemia.

A role for p53 in the in vivo progression of Friend virus-induced erythroleukemia has been suggested but not clearly defined. We developed a Friend virus-sensitive, p53-deficient mouse model to directly address the role of p53 in Friend erythroleukemia. When infected with the polycythemia-inducing strain of Friend virus (FVP), p53 null mice exhibited accelerated progression to erythroleukemia and accelerated death following diagnosis when compared to wild type mice. Confirmation that p53 mutations were required for disease progression was provided by sequence analysis of p53 transcripts in leukemic wild type and heterozygous mice. All transcripts evaluated had point mutations, deletions or insertions in the p53 gene. The ability to grow tumor colonies in vitro and derive cell lines was enhanced in FVP-infected p53 null animals. Although PU.1 oncogene overexpression is a common mutation observed in cell lines derived from Friend virus-infected p53 wild type mice, it was not a universal finding in cell lines derived from p53 null animals. Our data conclusively demonstrate that loss of p53 function is a requirement for progression of Friend erythroleukemia in vivo. Further, the data demonstrate that erythroleukemias arising in Friend virus-infected p53 null mice are biologically and genetically distinct from those that occur in wild type animals, suggesting that the temporal order of PU.1 and p53 mutations is an important parameter in the pathogenesis of leukemic development.

Animals↗