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PubMed2000

Aging and measures of processing speed.

Many variables have been assumed to reflect speed of processing, and most are strongly related to age in the period of adulthood. One of the primary theoretical questions with respect to aging and speed concerns the relative roles of specific and general age-related effects on particular speed variables. Distinguishing between specific (or unique) and general (or shared) age-related influences on measures of speed has been complicated, in part because the issues are sometimes framed in terms of extreme all-or-none positions, and because few researchers have employed analytical procedures suitable for estimating the relative contributions of each type of influence. However, recent methods focusing on partitioning age-related variance have indicated that large proportions of the age-related effects on individual speed variables are shared with age-related effects on other variables. Although these theoretical ideas and analytical procedures are fairly new, they may be relevant to a variety of psychophysiological or neurobiological variables.

Adult↗

PubMed1985

Shared idiotopes among antibodies encoded by heavy-chain variable region (VH) gene members of the J558 VH family as basis for cross-reactive regulation of clones with different antigen specificity.

A wide idiotype cross-reactivity was observed among six groups of monoclonal antibodies specific for arsonate and nitrophenyl haptens, hemagglutinin of PR8 and X31 influenza viruses, dextran, A48-idiotype, and a set of six monoclonal antibodies with unknown antigenic specificity. All of these antibodies are encoded by heavy-chain variable region (VH) genes belonging to the J558 VH family. This idiotypic cross-reactivity was determined by studying the binding of these antibodies to a panel of six monoclonal anti-idiotype antibodies, each one raised against a member of the six groups of monoclonal antibodies. The administration at birth of two such monoclonal anti-idiotype antibodies induced a long-lasting suppression not only of the corresponding idiotype but also of VH-related idiotypes with different antigenic specificities. These results suggest that the idiotypes encoded by VH genes that belong to the same VH gene family are interactive one with another. The possible physiological consequences of this immunochemical cross-reactivity are discussed.

Animals↗

PubMed1995

Accounting for variance shared by measures of personality and stress-related variables: a canonical correlation analysis.

Correlations were computed among the five personality scales of the NEO Personality Inventory, two measures derived from the Hassles Scale, and eight ways of dealing with stress measured by the Ways of Coping Questionnaire. Subjects were 66 undergraduate psychology students. Canonical correlation analysis suggests that multivariate procedures treating the data set as a whole can detect underlying patterns obscured by large sampling errors at lower levels of analysis.

Adaptation, Psychological↗

PubMed1984

A genetic and environmental analysis of a twin family study of alcohol use, anxiety, and depression.

Alcohol consumption, anxiety, and depression were measured by questionnaire in 572 twin families ascertained from the Institute of Psychiatry (London) normal twin register, each family consisting of an adult twin pair, their parents, and siblings--a total of 1,742 individuals. A multivariate normal model for pedigree analysis was applied to each variable, with power transformations fitted to maximise the fit with distributional assumptions. The effect of shared twin environment was estimated by considering the measured cohabitation history of twin pairs. For log-transformed alcohol consumption, amongst current drinkers this effect was the same for MZ and DZ pairs but depended on the cohabitation status of pairs. For both anxiety and depression the effect was clearly not the same for MZ and DZ pairs. Therefore the basic assumption of the classical twin method appears to be invalid for all three traits. Estimates of heritability derived from these analyses were compared with those obtained (1) by applying the classical twin method to twin data only, and (2) by a pedigree analysis ignoring the effect of shared twin environment. For all variables there were considerable differences between estimates based on the three models. This study illustrates that data from twins and their relatives which includes information on cohabitation history might distinguish shared genes and shared environment as causes of familial aggregation. In these behavioral traits the effect of shared twin environment may depend on zygosity and play a major role in explaining familial aggregation in twin family data.

Adolescent↗

PubMed2003

The role of cognitive variables in psychological functioning after the death of a first degree relative.

The present study sought to explore the relationship between negative cognitions and emotional problems after bereavement, with a group of 329 adults who had suffered the loss of a first degree relative. The following cognitions were assessed: global negative beliefs, cognitions about self-blame, negative cognitions about other people's responses after the loss, and negative cognitions about one's own grief reactions. Results showed that each of these cognitive variables was significantly related to the severity of symptoms of traumatic grief, depression and anxiety, even when background and loss-related variables that were initially found to influence symptom severity, were statistically controlled. When the shared variance between the cognitive variables was controlled, it was found that global negative beliefs about life, the world, and the future, and threatening interpretations of grief reactions each explained a unique proportion of variance in traumatic grief symptom severity. Global negative beliefs about life, the self and the future, and threatening interpretations of grief explained most variance in depression, while negative beliefs about the self and threatening interpretations of grief explained most variance in anxiety. Overall, the findings are in support of cognitive theories of grief, and suggest that effective treatment of problematic grief will need to address negative cognitions.

Anxiety Disorders↗

PubMed2005

[Bed sharing and sudden infant death].

BACKGROUND: The aim of the study was to investigate bed sharing as a risk factor for sudden infant death syndrome (SIDS). MATERIAL AND METHODS: Firstly, SIDS cases examined at our institute in two six-year periods before and after the back-to-sleep campaign (1984-89 and 1998-2003) were investigated. Secondly, a case-control study was performed, an investigation of variables such as bed sharing, parental smoking and breast-feeding in the SIDS group from the latter period versus 244 live control infants. RESULTS: The age distribution of the SIDS victims in the two periods with high and low SIDS rates differed significantly (p = 0.004). In the latter period, fewer SIDS cases were seen in the classical distributional peak between the third and the fourth month of life, and a larger proportion of SIDS cases were seen within the first month of life. Furthermore, a smaller proportion of SIDS victims were found dead in the prone position (decrease from 89% to 49%, p < 0.001); and bed sharing at time of death occurred more frequently (increase from 7% to 35%, p < 0.001). In the case-control study, bed sharing was a significant risk factor for SIDS in infants aged 0-2 months (multivariate OR 5.3; 95 % CI 1.3-22, p = 0.02). Bed sharing with a smoking mother was associated with a 16-fold increased risk of SIDS (OR 16; 95% CI 2.1 - 118, p = 0.007). No relationship between bed sharing and SIDS was evident for age >2 months. Only 12% of the bed sharing SIDS victims aged <2 months where found in the prone position. INTERPRETATION: Bed sharing is associated with an increased risk of SIDS for infants <2 months of age. Particularly hazardous is bed sharing with a smoking parent.

Breast Feeding↗

PubMed1999

[Determinants associated wtih the presence of risk behaviors in HIV infected patients].

BACKGROUND: Determinants associated with risk behaviours are evaluated in a known HIV-infected population not belonging to the great metropolitan nuclei. PATIENTS AND METHODS: 110 unselected HIV+ patients were interviewed, including 77 variables. Their association with sharing needles, and unprotected sex is analysed. RESULTS: Sharing needles was associated to: low academic achievement (p = 0.045), no children (p = 0.045), any physical limitation (p = 0.004), previous admission to detoxification unit (p = 0.014), and depression. With unprotected sex were associated: low academic achievement (p = 0.005), lesser time of HIV infection (p = 0.009), no family support (p = 0.005), and scanty information about HIV transmission (p = 0.018). CONCLUSIONS: A cohort of HIV-infected subjects who persist with risk practices is remaining. Some easily recognizable variables may be useful for their early recognition.

Adult↗

PubMed2002

Social support and zero sharing risk among hazardously drinking injection drug users.

We compared the sociodemographic, drug use, and social support characteristics of injection drug users (IDUs) who reported at least 6 months having not "shared needles or works" (zero sharing risk) with those who reported recent equipment sharing. 187 AUDIT-positive (>8), active IDUs were recruited between February 1998 and October 1999 from a needle exchange program in Providence, RI. The sample was 64% male and 87% white, with a mean age of 36 years, and 32% of subjects reported zero sharing risk in the prior 6 months. Variables having significant (P<.05) associations with zero sharing risk included: older age, lower heroin use frequency, lower cocaine use, and increased frequency of needle exchange visits. As social support from friends increased, the likelihood of sharing decreased. Subjects with substance-using friends or partners were significantly more likely to share than those without such associations (OR = 9.4; P<.05). Social support and social network composition influenced sharing behaviors in active, out-of-treatment drug injectors. Interventions that mobilize social support may increase the possibility of zero sharing, an important public health goal.

Adult↗

PubMed2004

Assessing whether an allele can account in part for a linkage signal: the Genotype-IBD Sharing Test (GIST).

To fine map genes, investigators often test for disease-marker association in chromosomal regions with evidence for linkage. Given a marker allele tentatively associated with disease, one would ask if this allele, or one in linkage disequilibrium (LD) with it, could account in part for the observed linkage signal. This question can be addressed by determining if families selected on the basis of the presence of the tentatively associated allele show stronger evidence of linkage as measured by increased allele sharing identical by descent (IBD) by affected family members. However, common selection strategies can be biased for or against linkage in the marker region, even given no disease-marker association. We define unbiased selection schemes and extend the definition to allow weighted selection on the basis of all genotyped family members. For affected-sibship data, we describe three genotype-based weight variables, corresponding to dominant, recessive, and additive models. We then introduce a test for association of a family weight variable with excess IBD sharing. This test allows us to determine if the linkage signal in a region can be attributed in part to the presence of a marker allele, either because of direct involvement in disease etiology or because of LD with a predisposing genetic variant. For samples of 500 affected sib pairs, the tests are powerful in detection of genotype-IBD sharing association, even for disease models with sib relative risk as low as lambda S=1.1, or when evidence for linkage is absent because of sampling variation. This makes our method a new tool for detecting linkage as well as association, especially in regions harboring a candidate gene. We have implemented these methods in the software package GIST (Genotype-IBD Sharing Test).

Computer Simulation↗

PubMed2004

Tangential load sharing among fingers during prehension.

The goal of the study was to examine the force sharing among the fingers during static prehension under systematic loading and postural changes. A custom-built handle was constructed that allowed for bi-directional loading (upward and downward) with different load magnitudes (250, 750 and 1250 g). Five- and three-digit grasps were tested. The fingers were spaced 2, 3 or 6 cm apart. The handle was oriented vertically such that the tangential forces acted parallel to the applied load. There were no differences in tangential sharing patterns between males and females. The factors that did affect the sharing pattern (ranked from the smallest to the largest effect) were: TRIAL (i.e., inter-trial variability), LOAD MAGNITUDE, SUBJECT, HAND POSTURE and LOAD DIRECTION. Normal force sharing accounted for much but not all of the variability in tangential sharing. The results suggest that loading direction should be considered when designing tools that require functional tangential forces for successful task completion (e.g., screwdrivers, jar lids, etc.). A hypothesis to account for the directional changes based on the passive properties of the fingers is proposed.

Adult↗

PubMed2005

Mitochondrial DNA spectra of single human CD34+ cells, T cells, B cells, and granulocytes.

Previously, we described the age-dependent accumulation of mitochondrial DNA (mtDNA) mutations, leading to a high degree of mtDNA heterogeneity among normal marrow and blood CD34+ clones and in granulocytes. We established a method for sequence analysis of single cells. We show marked, distinct mtDNA heterogeneity from corresponding aggregate sequences in isolated cells of 5 healthy adult donors-37.9% +/- 3.6% heterogeneity in circulating CD34+ cells, 36.4% +/- 14.1% in T cells, 36.0% +/- 10.7% in B cells, and 47.7% +/- 7.4% in granulocytes. Most heterogeneity was caused by poly-C tract variability; however, base substitutions were also prevalent, as follows: 14.7% +/- 5.7% in CD34+ cells, 15.2% +/- 9.0% in T cells, 15.4% +/- 6.7% in B cells, and 32.3% +/- 2.4% in granulocytes. Many poly-C tract length differences and specific point mutations seen in these same donors but assayed 2 years earlier were still present in the new CD34+ samples. Additionally, specific poly-C tract differences and point mutations were frequently shared among cells of the lymphoid and myeloid lineages. Secular stability and lineage sharing of mtDNA sequence variability suggest that mutations arise in the lymphohematopoietic stem cell compartment and that these changes may be used as a natural genetic marker to estimate the number of active stem cells.

Adult↗

PubMed1999

Highly related immunoglobulin light chain sequences in different multiple sclerosis patients.

Although immunoglobulin G and free light (L) chains of oligoclonal origin in cerebrospinal fluid (CSF) are the most common immunologic abnormalities in multiple sclerosis (MS), it is unknown whether homologous CSF L chain sequences are present in different individuals with MS. Using Southern blotting, a particular kappa (kappa) L chain variable region (V) probe was recently found to hybridize to Vkappa cDNA from CSF B cells from almost one half of the MS patients tested but only 10% of normal or other neurologic disease controls [Zhou, S.-R., Maier, C.C., Mitchell, G.W., LaGanke, C.C., Blalock, J.E., Whitaker, J.N., 1998. A cross-reactive idiotope in cerebrospinal fluid cells in multiple sclerosis: further evidence for the role of myelin basic protein. Neurology 50, 411-417.] Here, we report that this likely results from remarkable sequence similarity in certain Vkappa from CSF B cells from different individuals with MS. The high degree of sequence homology even extended to all three complementarity determining regions (CDR) which in part form an antibody combining site. In addition, marked sequence homology was observed between the light chains from the MS patients and those from certain mouse antibodies against myelin basic protein (MBP). The results establish, in principle, that the same or very similar kappa light chain variable regions can be shared between CSF B lymphocytes from different individuals with MS as well as with certain antibodies against MBP.

Amino Acid Sequence↗

PubMed1998

Independence of age-related influences on cognitive abilities across the life span.

Age-related increases in childhood and age-related decreases in adulthood have been reported for a wide variety of cognitive variables, but relatively little research has addressed the question of the independence of these influences. In this project, cross-sectional life span data (age 5 to 94 years) from the nationally representative sample used to establish the norms for the Woodcock-Johnson Psycho-Educational Battery (R. W. Woodcock & M. B. Johnson, 1989, 1990) were subjected to several types of analyses. The results indicated that the majority of age-related differences appear to be shared across different cognitive variables and are well predicted by individual differences in higher order factors. These findings suggest that the role of task-specific interpretations of developmental differences in cognition needs to be reevaluated to take into consideration the lack of independence of age-related influences on a variety of cognitive variables.

Adolescent↗

PubMed2005

Phylogenetic inference and comparative evolution of a complex microsatellite and its flanking regions in carnivores.

We sequenced locus Mel 08, with complex short repetitive motifs, in 24 carnivore species belonging to five different families in order to explore mutational changes in the region in the context of locus and species evolution. This non-coding locus includes up to four different parts or repetitive motifs showing size variability. The variability consists of repeat additions and deletions; substitutions, insertions and/or deletions creating interruptions in the repeat; and substitutions, insertions and deletions in the flanking regions. The locus has different repeat expansions in different carnivore subfamilies. We hypothesize that the complexity of this locus is due to a high mutation rate at an ancestral DNA sequence and, thus, prompts the emergence of repeats at mutational hotspots. High levels of homoplasy were evident, with nine electromorphs representing 28 haplotypes never shared across species. The variability in flanking regions was informative for phylogenetic inference and their evolutionary content. Tree topologies were congruent with relevant hypotheses on current conflicts in carnivore phylogenies, such as: (i) the monophyly of Lutrinae, (ii) the paraphyly of Mustelinae, (iii) the basal position of the Eurasian badger, Meles meles , in the Mustelidae, (iv) the classification of skunks as a separate family, Mephitidae, and (v) the placement of the red panda, Ailurus fulgens , as a monotypic family, Ailuridae, at a basal position in the Musteloidea.

Animals↗

PubMed1994

Immunoglobulin-like domain of HIV-1 envelope glycoprotein gp120 encodes putative internal image of some common human proteins.

By examining sequence similarity between the V3-loop of gp120 from various HIV-1 isolates and human proteins, we found that the V3 loop portion KKGIAIGPGR in strain New York 5 (HIV-1NY5) shares 70% identical residues with the collagen-like region (CLR) of human complement component C1q-A. C1q CLR was found to react with autoantibodies from several autoimmune disorders. Thus, we assumed that it would be of interest to find out the C1q reactivity with antibodies from AIDS sera. The results obtained show that the V3 loop-derived synthetic peptide KKGIAIGPGRTLY reacts both with AIDS patients sera and with antibodies purified on the V3 loop peptide-affinity column. The same affinity-purified antibodies bind also to C1q molecules. Since, according to our previous results, HIV-1 V3 loops and immunoglobulin heavy chain variable regions (Ig VH) share several common features, we suggest that the envelope of HIV-1NY5 bears a functional internal image of the C1q-A CLR epitope. Therefore, gp120 could manipulate the immune network and contribute to HIV-induced autoimmunity.

Amino Acid Sequence↗

PubMed2005

Histomorphometric characterisation of shared and non-shared cotyledonary villus territories of monochorionic placentae in relation to pregnancy complications.

OBJECTIVE: Theoretical estimates and physiological inferences suggest that the structure of a shared cotyledon differs from a non-shared cotyledon. The aim of this study was to characterise the histomorphometry of terminal villi in shared and non-shared cotyledons in monochorionic placentae, both from uncomplicated twins and from those with twin-twin transfusion syndrome (TTTS) or discordant growth restriction (DeltaIUGR). METHODS: Forty-one monochorionic placentae from Caucasian non-smokers were obtained at caesarean section. Their vascular anatomy and placental territories were ascertained by dye injection. After fixation, full thickness histological blocks were obtained by systematic random sampling from each twin's territory and the shared cotyledons. Fifty randomly selected terminal villi were assessed for: (i) median villus diameter (ii) median villus capillary diameter (iii) median fetomaternal diffusion distance (iv) median no. of capillaries/villus (v) degree of vascularization (median percentage cross-sectional area of terminal villi occupied by capillaries) using a stage micrometer and image analysis programme. The histomorphometric findings were then correlated with birthweight discordance, placental territory discordance and DeltaAVAs (no. of AVAs from smaller twin (donor) to larger twin (recipient) minus no. of AVAs from larger to smaller twin). RESULTS: Histomorphometric variables were similar in shared and non-shared cotyledons of uncomplicated MCDA twins. However, the median diameter of terminal villi in shared cotyledons in DeltaIUGR and TTTS placentae was significantly smaller [51.2 microm (48.2-58.3), p<0.001 and 52.6 microm (53.1-50.4), p<0.001], and had a similar number of smaller capillaries, larger fetomaternal diffusion distance and reduced vascularization compared to non-shared IUGR and TTTS placentae. However, Deltadiameter (defined as the difference between median diameters of terminal villi in large minus small twins' territories) rose with increasing birthweight discordance (Pearson correlation coefficient=0.82, p<0.001). Multiple linear regression analysis revealed that Deltadiameter was influenced by placental territory discordance (p<0.001) and birthweight discordance (p<0.01): log10 Deltadiameter=1.38+(0.01 x birthweight discordance)+(0.56 x log10 placental territory discordance) (R2=0.82, p<0.001), but there was no significant relationship with DeltaAVA and AAA. In the TTTS group, Deltadiameter correlated significantly with DeltaAVA only: log10Deltadiameter=1.44+(0.02 x DeltaAVA) (R2=0.3, p<0.001). CONCLUSIONS: This is the first study to characterise the histomorphometry of shared and non-shared cotyledons in MC twins. The findings suggest that abnormal placentation, rather than placental vascular anatomy may be responsible for DeltaIUGR in MC twins, whereas TTTS arises from imbalance in interfetal transfusion with resultant differing terminal villus histomorphometric features in donor, recipient and shared cotyledons.

Chorionic Villi↗

PubMed2001

Heterogeneity in sources of exposure variability among groups of workers exposed to inorganic mercury.

Many exposure assessment strategies rely on the occupational group as the unit of analysis in which workers are classified on the basis of job title, location, or on other characteristics related to the workplace or the job. Although statistical methods that combine exposure data collected on workers from different occupational groups are more efficient, the underlying assumption that the degree of variation over time and among workers is the same for all groups has yet to be fully investigated. Given the utility of different modeling approaches when assessing exposures, we investigated assumptions of homogeneity of variance within and between workers using both random- and mixed-effects models. In our study of four groups of workers exposed to inorganic mercury (Hg) at a chloralkali plant, there was no evidence of significant heterogeneity in the levels of variation over time or between workers for air Hg levels. For the biological monitoring data, however, our findings indicate that groups did not share common levels of variability and that it was not appropriate to pool the data and obtain single estimates of the within- and between-worker variance components. Classification of job group as a random or fixed effect had no effect on the results and yielded the same conclusions when the models were compared. To illustrate effects related to the proper specification of a model, the likelihood of exceeding certain levels (which is a function of the parameters of the underlying distribution of the natural log-transformed exposures) was evaluated using the results obtained from the different models. Although the probability that workers' mean exposures exceeded occupational exposure limits for air, urine and blood Hg was generally low (<10%) for all groups except maintenance workers, the estimated values sometimes varied depending upon the particular model that was applied. Given the growing use of random- and mixed-effects models that combine data across occupational groups, additional studies are warranted to evaluate whether it is reasonable to assume common variances and covariances among measurements collected on workers from different groups.

Analysis of Variance↗

PubMed1991

The sharing of injecting equipment among drug users attending prescribing clinics and those using needle-exchanges.

Three groups of injecting drug-users were defined in terms of their experience of methadone treatment: treatment for periods longer than 6 months, treatment for shorter periods, and no treatment. Methadone treatment and the use of needle exchanges were related in subsequent analysis to the sharing of injecting equipment. Comparisons between groups were made on other variables believed to be associated with sharing. Significant differences were observed between treatment groups in the recency of sharing and in the use of needle-exchanges. Age and length of drug use were important factors in sharing, which was least prevalent among older respondents in long-term treatment. Regular use of needle-exchanges was associated with the passing on of used equipment to others. Subsequent analysis of regular users suggested respondents in long-term treatment were less likely to pass on their equipment than those in the other two groups.

Adolescent↗