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PubMed1996

Pathogenesis of schizophrenic delusions and hallucinations: a neural model.

We implement and study a computational model of Stevens' theory of the pathogenesis of schizophrenia. This theory hypothesizes that the onset of schizophrenia is associated with reactive synaptic regeneration in brain regions that receive degenerating temporal lobe projections. Concentrating on one such area, the frontal cortex, we model a frontal module as an associative memory neural network whose input synapses represent incoming temporal projections. Modeling Stevens' hypothesized pathological synaptic changes in this framework results in adverse side effects similar to hallucinations and delusions seen in schizophrenia: spontaneous, stimulus-independent retrieval of stored memories focused on just a few of the stored patterns. These could account for the delusions and hallucinations that occur in schizophrenia without any apparent external trigger and for their tendency to concentrate on a few central cognitive and perceptual themes. The model explains why the positive symptoms of schizophrenia tend to wane as the disease progresses, why delayed therapeutic intervention leads to a much slower response, and why delusions and hallucinations may persist for a long time when they do occur.

Brain↗

PubMed1993

Equivalent electrical source analysis of pain-related somatosensory evoked potentials elicited by a CO2 laser.

The purpose of this study was to localize possible neural sources of pain-related cortical evoked potentials. A brain electrical source analysis was performed on late somatosensory evoked potential data (500-ms window was analyzed) elicited by short heat pulses produced by a CO2 laser. These stimuli activate pain and temperature pathways. The first, fairly small, negative response can be recorded on the scalp about 160 ms from the stimulus (N1 component). The major negativity on the scalp has its peak about 240 ms from the stimulus and is followed by a positivity (N2 and P2 components). A four-dipole model was developed using data following left-hand stimulation. Spatiotemporal source analysis suggested that the N1 component could be generated by contralateral activity in both primary and secondary somatosensory cortices and that N2 could be generated by bilateral activity mainly in secondary somatosensory cortices. A deep dipole in the midline was active during the time range of the negative potentials and seemed to be mostly responsible for the P2 component. This dipole was located too frontally to be thalamic, but it corresponded well to the location of the anterior cingulate gyrus. The model also yielded good fits for right-hand and left-foot stimulation data and, in addition, another set of left-hand data obtained with different electrode spacing in a different group of subjects (residual variances from 2.8% to 3.3%). The model explaining data sets from different body part stimulations varied very little, except with respect to the location of the dipole representing the activity of the primary somatosensory area.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Attitudinal and behavioral correlates of condom use in urban adolescent males.

To determine correlates of condom use in adolescent males, we administered a sexual behavior questionnaire to 105 urban males attending a general adolescent clinic. The mean age was 16.5 +/- 1.6 years, and all reported heterosexual activity during the prior 3 months. Condom use was significantly (p less than 0.05) associated with perceived hassle of use (Spearman's rho = -0.40), perception of girlfriend's attitude toward condoms (rho = -0.36), self-confidence in correct use (rho = 0.26), younger age (rho = 0.25), reported degree of exposure to sexually transmitted disease (STD) education (rho = 0.23), perceived condom safety (rho = 0.23), and perceived risk of STD if not wearing a condom (rho = 0.21). Using stepwise multiple regression, four variables explained a significant amount of variation in condom use: perceived hassle of use, perceived girlfriend's attitude toward condom use, age, and self-confidence in correct use (adjusted R2 = 0.28, p less than 0.001). Intention to use free condoms was significantly (p less than 0.05) associated with past use (rho = 0.63), girlfriend's attitude toward use (rho = -0.46), self-confidence in correct use (rho = 0.36), perceived hassle (rho = -0.31), and degree of exposure to STD education (rho = 0.25). Three variables in a regression model explained a significant amount of variation in intent to use free condoms: self-reported past use, girlfriend's attitude, and self-confidence in correct use (adjusted R2 = 0.51, p less than 0.001).

Adolescent↗

PubMed2003

Tackling health inequalities in the United Kingdom: the progress and pitfalls of policy.

GOAL: Assess the progress and pitfalls of current United Kingdom (U.K.) policies to reduce health inequalities. OBJECTIVES: (1) Describe the context enabling health inequalities to get onto the policy agenda in the United Kingdom. (2) Categorize and assess selected current U.K. policies that may affect health inequalities. (3) Apply the "policy windows" model to understand the issues faced in formulating and implementing such policies. (4) Examine the emerging policy challenges in the U.K. and elsewhere. DATA SOURCES: Official documents, secondary analyses, and interviews with policymakers. STUDY DESIGN: Qualitative, policy analysis. DATA COLLECTION: 2001-2002. The methods were divided into two stages. The first identified policies which were connected with individual inquiry recommendations. The second involved case-studies of three policies areas which were thought to be crucial in tackling health inequalities. Both stages involved interviews with policymakers and documentary analysis. PRINCIPAL FINDINGS: (1) The current U.K. government stated a commitment to reducing health inequalities. (2) The government has begun to implement policies that address the wider determinants. (3) Some progress is evident but many indicators remain stubborn. (4) Difficulties remain in terms of coordinating policies across government and measuring progress. (5) The "policy windows" model explains the limited extent of progress and highlights current and possible future pitfalls. (6) The U.K.'s experience has lessons for other governments involved in tackling health inequalities. CONCLUSIONS: Health inequalities are on the agenda of U.K. government policy and steps have been made to address them. There are some signs of progress but much remains to be done including overcoming some of the perverse incentives at the national level, improving joint working, ensuring appropriate measures of performance/progress, and improving monitoring arrangements. A conceptual policy model aids understanding and points to ways of sustaining and extending the recent progress and overcoming pitfalls.

Health Plan Implementation↗

PubMed1988

Identification of high caries risk adults: attitudes, social factors and diseases.

Since agent, host and environmental factors have been associated with caries, the development of multivariate risk assessment models is warranted. This process comprises the identification of risk factors, the development and testing of risk models, assessment and targeting. Work-in-progress by the authors in delineating oral, social/behavioural and medical risk factors for root caries in older adults shows that regression models explain 48 per cent of the variance in root caries scores for males and 47 per cent for females. Discriminant analyses using the risk factors identified in the regressions differentiated between people who did and did not get root caries during an 18-month period. The sensitivity of the predictions for men was 0.75 and the specificity was 0.79. For women, the sensitivity was 0.79 and the specificity was 0.83. These results suggest that it will be possible to develop a clinically useful risk assessment model. Future studies should include data on oral risk factors, such as micro-organisms present, salivary flow and buffering capacity, that can be added to the multivariate model.

Adult↗

PubMed1993

Mathematical model of the cut-off effect in the homologous series of tertiary amine local anesthetics.

It is proposed a simple mathematical model explaining the quasi parabolic dependence of the local anesthetic activity on the length of hydrophobic substituent in the homologous series of tertiary amines (TA). It is suggested that the molecules of TA intercalate between the lipid molecules in bilayers. Due to the mismatch between the lengths of lipid and TA hydrocarbon chains the intercalation results in a decrease in the bilayer thickness. The quasi parabolic dependence is the result of combination of partition equilibria and of geometrical parameters of interacting molecules in the bilayer. The model predicts that the TA chain length at which the maximum activity is observed should be dependent on the lipid: aqueous phase volume ratio. The empirical parameters used in the model are obtained from the X-ray diffraction on multilamellar egg yolk phosphatidylcholine (EYPC) dispersions with the monohydrochloride of [2-(heptyloxy)phenyl]-2-(1-piperidinyl)ethyl ester of carbamic acid and from the partition equilibria of its alkyloxy homologs with unilamellar EYPC liposomes.

Amines↗

PubMed2000

Neonatal assisted ventilation: predictors, frequency, and duration in a mature managed care organization.

OBJECTIVES: Reference data are lacking on the frequency and duration of assisted ventilation in neonates. This information is essential for determining resource needs and planning clinical trials. As mortality becomes uncommon, ventilator utilization is increasingly used as a measure for assessing therapeutic effect and quality of care in intensive care medicine. Valid comparisons require adjustments for differences in a patient's baseline risk for assisted ventilation and prolonged ventilator support. The aims of this study were to determine the frequency and length of ventilation (LOV) in preterm and term infants and to develop models for predicting the need for assisted ventilation and length of ventilator support. METHODS: We performed a retrospective, population-based cohort study of 77 576 inborn live births at 6 Northern California hospitals with level 3 intensive care nurseries in a group-model managed care organization. The gestational age-specific frequency and duration of assisted ventilation among surviving infants was determined. Multivariable regression was performed to determine predictors for assisted ventilation and LOV. RESULTS: Of 77 576 inborn live births in the study, 11 199 required admission to the neonatal intensive care unit and of these, 1928 survivors required ventilator support. The proportion of infants requiring assisted ventilation and the median LOV decreased markedly with increasing gestational age. In addition to gestational age, admission illness severity, 5-minute Apgar scores, presence of anomalies, male sex, and white race were important predictors for the need for assisted ventilation. The ability of the models to predict need for ventilation was high, and significantly better than birth weight alone with an area under the receiver operating characteristic curve of.90 versus.70 for preterm infants, and.88 versus.50 for term infants. For preterm infants, gestational age, admission illness severity, oxygenation index, anomalies, and small-for-gestational age status were significant predictors for LOV, accounting for 60% of the variance in the length of assisted ventilation. For term infants, oxygenation index and anomalies were significant predictors but only accounted for 29% of the variance. CONCLUSIONS: Considerable variation exists in the utilization of ventilator support among infants of closely related gestational age. In addition, a number of medical risk factors influence the need for, and length of, assisted ventilation. These models explain much of the variance in LOV among preterm infants but explain substantially less among term infants.neonatal intensive care, assisted ventilation, Score for Neonatal Acute Physiology, resource consumption, prematurity.

California↗

PubMed2004

Factors related to the inability of individuals with low back pain to improve with a spinal manipulation.

BACKGROUND AND PURPOSE: Although spinal manipulation is one of the few interventions for low back pain supported by evidence, it appears to be underutilized by physical therapists, possibly due to therapists' concerns that a patient may not benefit from the intervention. The purpose of this study was to identify factors that are associated with an inability to benefit from manipulation. SUBJECTS: Seventy-five people with nonradicular low back pain (mean age=37.6 years, SD=10.6, range=19-59; mean duration of symptoms=41.7 days, SD=54.7, range=1-252) participated. METHODS: Subjects underwent a standardized examination that included history-taking; self-reports of pain, disability, and fear-avoidance beliefs; measurement of lumbar and hip range of motion; and use of various tests. All subjects received a spinal manipulation intervention for a maximum of 2 sessions. Subjects who did not show greater than 5 points of improvement on the modified Oswestry Low Back Pain Disability Questionnaire were considered to have shown no improvement with the manipulation. Baseline variables were tested for univariate relationship with the outcome of the manipulation. Variables showing a univariate relationship were entered into a logistic regression equation, and adjusted odds ratios were calculated. RESULTS: Twenty subjects (28%) did not improve with manipulation. Six variables were identified as being related to inability to improve with manipulation: longer symptom duration, having symptoms in the buttock or leg, absence of lumbar hypomobility, less hip rotation range of motion, less discrepancy in left-to-right hip medial rotation range of motion, and a negative Gaenslen sign. The resulting logistic regression model explained 63% of the variance in manipulation outcome. DISCUSSION AND CONCLUSION: The majority of subjects improved with manipulation. Baseline variables could be identified that were predictive of which subjects would not improve.

Adult↗

PubMed1994

A population-based study of gastroschisis: demographic, pregnancy, and lifestyle risk factors.

Gastroschisis, an abdominal wall defect, most often occurs in infants of young mothers. To identify risk factors for gastroschisis, we conducted a case-control study in the population surveyed by the California Birth Defects Monitoring Program (CBDMP). From structured questionnaire data, we compared sociodemographic, reproductive, and lifestyle factors for 110 mothers of infants with gastroschisis with those for 220 age-matched mothers of normal infants. Univariate matched-pair analysis showed significant associations of gastroschisis with mother's education, yearly family income, marital status, a history of mother's mother smoking, mother's father's absence from home during the mother's youth, more than one elective abortion, a short interval between menarche and first pregnancy, siblings from different fathers, and use of either a recreational drug (either cocaine, amphetamine, marijuana, or LSD), alcohol, or tobacco during the trimester preceding pregnancy. For cocaine, amphetamine, and marijuana, use of more than one drug showed a stronger association than single drug use. The association was stronger if both parents used drugs. Although many variables were correlated, odds ratios (OR) were significant (95% confidence intervals) in multivariate conditional logistic analysis for: yearly family income < $10,000 [OR = 4.34 (1.54, 12.22)] or $10,000-$49,999 [OR = 3.93 (1.43, 10.80)]; mother's mother's smoking status not known [OR = 3.99 (1.66, 9.56)]; mother's father's absence from home during her youth [OR = 3.11 (1.14, 8.46)]; and drug use by mother [OR = 2.21 (1.21, 4.03)], father [OR = 1.66 (1.02, 2.69)], or both [OR = 3.05 (1.48, 6.28)]. The best predictive model explained 32% of the deviance. Young, socially disadvantaged women with a history of substance use were at highest risk for a child with a gastroschisis.

Abdominal Muscles↗

PubMed1999

Primary HIV infection of infants: the effects of somatic growth on lymphocyte and virus dynamics.

Acute HIV infection is characterized by the appearance of high concentrations of virus in the peripheral blood. In adults, this high-level viremia spontaneously abates after several weeks. In contrast, after perinatal infection of infants, blood virus levels remain high for many months, during which the concentration of circulating CD4+ lymphocytes remains well above normal values for adults. Here we suggest an explanation for these differences, based on developmental factors including somatic growth and immunological ontogeny. Flow cytometric analysis revealed that at birth the thymus contains elevated levels of mature T lymphocytes, compared to the thymus after 3 months of age. A mathematical model is proposed incorporating immunological and virological data from longitudinally evaluated infants who acquired infection at the time of birth. This model explains the pattern of high-level viremia in infants as resulting from the replication of HIV within the progressively expanding lymphoid cell mass.

Adult↗

PubMed1982

Steady states and the effects of ouabain in the Necturus gallbladder epithelium: a model analysis.

A simple numerical model for the Necturus gallbladder epithelium is presented. K+, Na+ and Cl- cross the mucosal and serosal membranes as well as the junctions by means of electrodiffusion; furthermore the mucosal membrane contains a neutral entry mechanism for NaCl and the serosal membrane contains an active pump for K+ and Na+. The values which have been used for the model are taken from the literature. The model can only attain steady states if the resistance of the serosal membrane is lower than 1000 omega cm2. Values reported in the literature for the resistance of this membrane vary from about 3000 to about 100 omega cm2. We shall argue, however, that the higher estimates are in error because they are derived from a model of the tissue in which each membrane and the junction are modeled by a resistor; this procedure is invalid because the resistance of the lateral intercellular space relative to the resistance of the tight junctions is neglected and consequently the resistance of the serosal membrane is overestimated by a factor of about four. Apart from predicting a realistic steady state at normal external concentrations the model can predict quantitatively several experimental results obtained from the living epithelium. We have focused on the experiments which test the permeabilities of the serosal membrane and the properties of the pump: i) Replacement of serosal Cl- by an impermeant ion. ii) Replacement of serosal K+ by Na+. iii) Inhibiting the (Na+, K+)-pump. The best correspondence between model and experiments is obtained when the pump is assumed to be electrogenic (or rheogenic) with a ratio of coupling between Na+ and K+ of 3:2. In this case both model and direct experiments (also presented in this paper) show an initial abrupt depolarization of 6 to 7 mV. The model also shows that it cannot be concluded from i and ii that the Cl- permeability of the serosal membrane is low. The model explains, even with high passive Cl- permeabilities, why the intracellular Cl- concentration is relatively unaffected by paracellular currents, a fact which in other epithelia has been taken as an implication of a low Cl- permeability of the serosal membranes.

Animals↗

PubMed2005

Dual roles of an E-helix residue, Glu167, in the transcriptional activator function of CooA.

CooA is a transcriptional activator that mediates CO-dependent expression of the genes responsible for CO oxidation in Rhodospirillum rubrum. In this study, we suggest in vitro and in vivo models explaining an unusual requirement of CooA for millimolar levels of divalent cations for high-affinity DNA binding. Several lines of evidence indicate that an E-helix residue, Glu167, plays a central role in this requirement by inhibiting sequence-specific DNA binding via charge repulsion in the absence of any divalent cation and that divalent cations relieve such repulsion in the process of DNA binding by CooA. Unexpectedly, the Glu167 residue is the optimal residue for in vivo transcriptional activity of CooA. We present a model in which the Glu167 from the downstream subunit of CooA helps the protein to interact with RNA polymerase, probably through an interaction between activating region 3 and sigma subunit. The study was further extended to a homologous protein, cyclic AMP receptor protein (CRP), which revealed similar, but not identical, roles of the residue in this protein as well. The results show a unique mechanism of CooA modulating its DNA binding and transcriptional activation in response to divalent cations among the CRP/FNR (fumarate and nitrate reductase activator protein) superfamily of regulators.

Bacterial Proteins↗

PubMed1994

Gonosomal mosaicism in myotonic dystrophy patients: involvement of mitotic events in (CTG)n repeat variation and selection against extreme expansion in sperm.

Myotonic dystrophy (DM) is caused by abnormal expansion of a polymorphic (CTG)n repeat, located in the DM protein kinase gene. We determined the (CTG)n repeat lengths in a broad range of tissue DNAs from patients with mild, classical, or congenital manifestation of DM. Differences in the repeat length were seen in somatic tissues from single DM individuals and twins. Repeats appeared to expand to a similar extent in tissues originating from the same embryonal origin. In most male patients carrying intermediate- or small-sized expansions in blood, the repeat lengths covered a markedly wider range in sperm. In contrast, male patients with large allele expansions in blood (> 700 CTGs) had similar or smaller repeats in sperm, when detectable. Sperm alleles with > 1,000 CTGs were not seen. We conclude that DM patients can be considered gonosomal mosaics, i.e., combined somatic and germ-line tissue mosaics. Most remarkably, we observed multiple cases where the length distributions of intermediate- or small-sized alleles in fathers' sperm were significantly different from that in their offspring's blood. Our combined findings indicate that intergenerational length changes in the unstable CTG repeat are most likely to occur during early embryonic mitotic divisions in both somatic and germ-line tissue formation. Both the initial CTG length, the overall number of cell divisions involved in tissue formation, and perhaps a specific selection process in spermatogenesis may influence the dynamics of this process. A model explaining mitotic instability and sex-dependent segregation phenomena in DM manifestation is discussed.

Aged↗

PubMed1990

The third birth in Sweden.

"This paper considers the formulation, estimation and interpretation of microdynamic models of fertility. Our model explains parity choices, sterility, childlessness, interbirth intervals and initiation of pregnancy within a unified framework. We develop a general methodology for estimating the determinants of transition times to births of different orders. Our procedure incorporates time-varying explanatory variables and unobservables. We present conditions that justify conventional formulae relating hazards to survivor functions when time-varying variables enter hazards. We also consider the validity of widely-used piecemeal estimation strategies that focus on one birth at a time. We consider methods for selecting a best model among a class of non-nested models. Two criteria are set forth and used to evaluate the determinants of third births in Sweden."

Birth Order↗

PubMed2005

Protein linear indices of the 'macromolecular pseudograph alpha-carbon atom adjacency matrix' in bioinformatics. Part 1: prediction of protein stability effects of a complete set of alanine substitutions in Arc repressor.

A novel approach to bio-macromolecular design from a linear algebra point of view is introduced. A protein's total (whole protein) and local (one or more amino acid) linear indices are a new set of bio-macromolecular descriptors of relevance to protein QSAR/QSPR studies. These amino-acid level biochemical descriptors are based on the calculation of linear maps on Rn[f k(xmi):Rn-->Rn] in canonical basis. These bio-macromolecular indices are calculated from the kth power of the macromolecular pseudograph alpha-carbon atom adjacency matrix. Total linear indices are linear functional on Rn. That is, the kth total linear indices are linear maps from Rn to the scalar R[f k(xm):Rn-->R]. Thus, the kth total linear indices are calculated by summing the amino-acid linear indices of all amino acids in the protein molecule. A study of the protein stability effects for a complete set of alanine substitutions in the Arc repressor illustrates this approach. A quantitative model that discriminates near wild-type stability alanine mutants from the reduced-stability ones in a training series was obtained. This model permitted the correct classification of 97.56% (40/41) and 91.67% (11/12) of proteins in the training and test set, respectively. It shows a high Matthews correlation coefficient (MCC=0.952) for the training set and an MCC=0.837 for the external prediction set. Additionally, canonical regression analysis corroborated the statistical quality of the classification model (Rcanc=0.824). This analysis was also used to compute biological stability canonical scores for each Arc alanine mutant. On the other hand, the linear piecewise regression model compared favorably with respect to the linear regression one on predicting the melting temperature (tm) of the Arc alanine mutants. The linear model explains almost 81% of the variance of the experimental tm (R=0.90 and s=4.29) and the LOO press statistics evidenced its predictive ability (q2=0.72 and scv=4.79). Moreover, the TOMOCOMD-CAMPS method produced a linear piecewise regression (R=0.97) between protein backbone descriptors and tm values for alanine mutants of the Arc repressor. A break-point value of 51.87 degrees C characterized two mutant clusters and coincided perfectly with the experimental scale. For this reason, we can use the linear discriminant analysis and piecewise models in combination to classify and predict the stability of the mutant Arc homodimers. These models also permitted the interpretation of the driving forces of such folding process, indicating that topologic/topographic protein backbone interactions control the stability profile of wild-type Arc and its alanine mutants.

Alanine↗

PubMed1983

Endothelium-dependent and nitrovasodilator-induced relaxation of vascular smooth muscle: role of cyclic GMP.

The mechanisms by which endothelium-dependent relaxants and nitrovasodilators cause relaxation of vascular smooth muscle has been reviewed. A model explaining these observations is summarized in Fig. 1. The endothelium-dependent vasodilators through interaction with their appropriate receptors are thought to activate phospholipase A2 and cause the release of an unsaturated fatty acid. The released unsaturated fatty acid or a metabolite is thought to be the "endothelial relaxant factor" that interacts with the smooth muscle component to cause relaxation. While the unsaturated fatty acid may be oxidized in either the endothelial cell or smooth muscle cell, the lability of the endothelial relaxant factor suggests that at least some of this processing occurs before its release from the endothelium. the model in Figure 1 suggests that an oxidized fatty acid or a derived free radical is responsible for activation of smooth muscle guanylate cyclase and increases in cyclic GMP levels. As pointed out above, the use of various inhibitors of fatty acid release and metabolism has not allowed us or others to predict the structure of the active material. To date the best evidence suggests that the unsaturated fatty acid is a product of either the lipoxygenase or P-450 pathways. Nitrovasodilators are thought to form nitric oxide free radical and directly activate guanylate cyclase as described above. Activated guanylate cyclase, whether by endothelium dependent agents or the nitrovasodilators, then increases the formation of cyclic GMP, which activates cyclic GMP-dependent protein kinase. The phosphorylation state of various proteins is then altered and, eventually, myosin light chain is dephosphorylated and relaxation occurs. Whether this mechanism involves cyclic GMP-dependent changes in activities of myosin light chain kinase and/or myosin light chain phosphatase remains to be determined. Although the altered phosphorylation state of myosin light chain that results from cyclic GMP accumulation may explain the mechanisms of action of cyclic GMP in smooth muscle relaxation, other mechanisms can not be excluded. For example, some additional studies which we have not summarized here indicate that the integrity of the membrane and Na+-K+ pump can modify both cyclic GMP synthesis and relaxation in rat aorta (38 and unpublished observations). Apparently complex interactions may exist in smooth muscle and other tissues which regulate cyclic GMP accumulation and/or its expression on some process. While several functions for cyclic GMP have been suggested, there is considerable evidence which suggests that one of its roles is relaxation of airway and vascular smooth muscle.

Animals↗

PubMed2000

ATP-activated oligomerization as a mechanism for apoptosis regulation: fold and mechanism prediction for CED-4.

Fold recognition algorithm FFAS (Rychlewski et al., Protein Sci, 2000;9:232-241) was used to match the nucleotide-binding adaptor shared by APAF-1, certain R gene products and CED-4 (NB-ARC domain) to the structure of the D2 domain of N-ethylemaleimide-Sensitive Fusion Protein and the delta; subunit of clamp loader of DNA polymerase III. The predicted structure consists of the p-loop ATP-binding domain, followed by two alpha-helical domains that regulate the oligomerization process. This prediction suggests a detailed molecular mechanism for the "induced proximity" hypothesis (Salvesen and Dixit, Proc Natl Acad Sci USA 1999;96:10964-10967) for CED3/caspase-9 activation by CED4/APAF-1 complex. According to this model, the ATP binding acts as a trigger in CED-4 oligomerization and the helical domain immediately following the ATP-binding domain provides additional mechanisms for regulation of the oligomerization process. This model explains most of known experimental data about CED-4-mediated caspase activation and, at the same time, suggest experiments that could test this hypothesis.

Adenosine Triphosphate↗

PubMed1997

Combining cultural, social and personality trait variables as predictors for drug use among adolescents in Zimbabwe.

A classroom survey among 3061 secondary school students in four provinces in Zimbabwe was conducted in 1994. This paper presents analyses of the relationship between a set of predictors including personality trait, social and cultural variables and drug use. A two-stage sampling strategy distinguished between four different socio-cultural groups. Multiple regression was applied to analyse the impact of sensation-seeking, addictive behaviour of significant others, and Global and Local cultural orientation on drug use, controlling for age, gender and socio-cultural subgroup. The model explained 29.7% of the variance in the dependent drug use variable and the two cultural orientation variables were found to contribute significantly in addition to the personality trait and the social variables.

Adolescent↗