Recombinant IGF-1/BP3 protects against intestinal injury in a neonatal mouse NEC model

BACKGROUND

Recombinant human IGF-1/binding protein-3 (rhIGF-1/BP3) is currently being tested in phase II clinical trials in premature infants to prevent bronchopulmonary dysplasia, but its impact on the neonatal intestine remains unclear. The aim of this study was to determine whether rhIGF-1/BP3 protects against necrotizing enterocolitis (NEC) in mice and to investigate the mechanisms involved.

METHODS

Neonatal mice were dam fed or injected intraperitoneally with rhIGF-1/BP3 (or vehicle) and submitted to an experimental NEC model. Serum IGF-1 was assessed by ELISA and intestinal vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR2) expression by Western blot. Intestinal endothelial cell proliferation, and enterocyte proliferation and migration were examined by immunofluorescence. Pup survival and histological intestinal injury were determined.

RESULTS

In pups exposed to experimental NEC, serum IBP3-bound IGF-1 level was decreased. Exogenous rhIGF-1/BP3 preserved VEGF and VEGFR2 protein expression, decreased vascular permeability, and preserved endothelial cell proliferation in the small intestine. Furthermore, rhIGF-1/BP3 promoted enterocyte proliferation and migration, which effects were attenuated by inhibiting VEGFR2 signaling, decreased enterocyte apoptosis and decreased systemic and intestinal inflammation. rhIGF-1/BP3 improved survival and reduced the incidence of severe intestinal injury in experimental NEC.

CONCLUSIONS

Exogenous rhIGF-1/BP3 protects neonatal mice against experimental NEC via multiple mechanisms.

IMPACT

Exogenous rhIGF-1/BP3 preserves intestinal microvascular development and integrity, promotes enterocyte proliferation and migration, decreases local and systemic inflammation, and protects neonatal mice against NEC. The article adds pre-clinical evidence of a protective role for rhIGF-1/BP3 on the premature gut. It provides evidence supporting the use of rhIGF1/BP3 in premature neonates to protect against NEC.

Evaluation of recombinant human IGF-1/IGFBP-3 on intraventricular hemorrhage prevention and survival in the preterm rabbit pup model

Insulin-like growth factor-1 (IGF-1) is essential for normal brain development and regulates processes of vascular maturation. The pathogenesis of intraventricular hemorrhage (IVH) relates to the fragility of the immature capillaries in the germinal matrix, and its inability to resist fluctuations in cerebral blood flow. In this work, using different experimental setups, we aimed to (i) establish an optimal time-point for glycerol-induction of IVH in relation to time-point of recombinant human (rh) IGF-1/rhIGFBP-3 administration, and (ii) to evaluate the effects of a physiologic replacement dose of rhIGF-1/rhIGFBP-3 on prevention of IVH and survival in the preterm rabbit pup. The presence of IVH was evaluated using high-frequency ultrasound and post-mortem examinations. In the first part of the study, the highest incidence of IVH (> 60%), occurred when glycerol was administered at the earliest timepoint, e.g., 6 h after birth. At later time-points (18 and 24 h) the incidence decreased substantially. In the second part of the study, the incidence of IVH and mortality rate following rhIGF-1/rhIGFBP-3 administration was not statistically different compared to vehicle treated animals. To evaluate the importance of maintaining intrauterine serum levels of IGF-1 following preterm birth, as reported in human interventional studies, additional studies are needed to further characterize and establish the potential of rhIGF-1/rhIGFBP-3 in reducing the prevalence of IVH and improving survival in the preterm rabbit pup.

Characterization of choroid plexus in the preterm rabbit pup following subcutaneous administration of recombinant human IGF-1/IGFBP-3

Insulin-like growth factor-1 (IGF-1) is essential for normal brain development and regulates essential processes of vascular maturation and stabilization. Importantly, preterm birth is associated with reduced serum levels of IGF-1 as compared to in utero levels. Using a preterm rabbit pup model, we investigated the uptake of systemic recombinant human (rh) IGF-1 in complex with its main binding protein IGF-binding protein 3 (BP-3) to the brain parenchyma via the choroid plexus. Five hours after subcutaneous administration, labeled rhIGF-1/rhIGFBP-3 displayed a widespread presence in the choroid plexus of the lateral and third ventricle, however, to a less degree in the fourth, as well as in the perivascular and subarachnoid space. We found a time-dependent uptake of IGF-1 in cerebrospinal fluid, decreasing with postnatal age, and a translocation of IGF-1 through the choroid plexus. The impact of systemic rhIGF-1/rhIGFBP-3 on IGF-1 receptor activation in the choroid plexus decreased with postnatal age, correlating with IGF-1 uptake in cerebrospinal fluid. In addition, choroid plexus gene expression was observed to increase with postnatal age. Moreover, using choroid plexus in vitro cell cultures, gene expression and protein synthesis were further investigated upon rhIGF-1/rhIGFBP-3 stimulation as compared to rhIGF-1 alone, and found not to be differently altered. Here, we characterize the uptake of systemic rhIGF-1/rhIGFBP-3 to the preterm brain, and show that the interaction between systemic rhIGF-1/rhIGFBP-3 and choroid plexus varies over time.

60 POWER-AGERS: IMPLEMENTING PROGRESSIVE RESISTANCE TRAINING TO MANAGE SARCOPENIA AMONG COMMUNITY DWELLING OLDER ADULTS

Background

The prevalence of sarcopenia among community dwelling older adults is between 10-40%. Progressive Resistance Training (PRT) improves sarcopenia and functional performance among older-adults. A PRT programme was introduced to a Day Hospital service as part of a sarcopenia management quality improvement initiative.

Methods

The PRT programme was implemented on a phased basis. Phase 1 evaluated the feasibility, safety and participant satisfaction. Phase 2 then collected pre and post outcome measures (gait-speed, grip strength and 5-Times-Sit-to-Stand [5TSTS]), and a patient perception questionnaire. The intervention consisted of a physiotherapist-lead PRT programme (weekly in phase 1 and biweekly in phase 2). Recent community dwelling Day Hospital attendees were recruited by the physiotherapist to participate. The class consisted of a circuit of 4-6 exercises targeting upper and lower limbs, along with an educational component. Exercises were progressively overloaded on an individual basis.

Results

Ten participants attended the PRT programmes (phase 1 [n=5], phase 2 [n=5]). Most were female (n=6), mean age was 84 years. None had prior formal experience of PRT. The phase 1 PRT group was deemed feasible and safe in an outpatient setting. All phase 1 participants (n=5) felt it was beneficial and rated it 5/5. All phase 2 participants had improvements in sarcopenia markers (grip strength [range=1kg-9kg], gait-speed [range=0.04m/s-0.19m/s], and 5TSTS [range=5.1sec-11sec]). All participants reported that the programmes improved their confidence in PRT and that they were interested in continuing PRT in the future.

Conclusion

This supports that PRT a clinical setting with community dwelling older adults is safe, feasible and effective in improving sarcopenia markers. Furthermore, the high rate of satisfaction supports its use with this population. Further research is required to examine the impact of combined nutritional education with strength training as an intervention for older adults with sarcopenia.

Clinical outcome and gut development after insulin-like growth factor-1 supplementation to preterm pigs

BACKGROUND

Elevation of circulating insulin-like growth factor-1 (IGF-1) within normal physiological levels may alleviate several morbidities in preterm infants but safety and efficacy remain unclear. We hypothesized that IGF-1 supplementation during the first 1-2 weeks after preterm birth improves clinical outcomes and gut development, using preterm pigs as a model for infants.

METHODS

Preterm pigs were given vehicle or recombinant human IGF-1/binding protein-3 (rhIGF-1, 2.25 mg/kg/d) by subcutaneous injections for 8 days (Experiment 1, n = 34), or by systemic infusion for 4 days (Experiment 2, n = 19), before collection of blood and organs for analyses.

RESULTS

In both experiments, rhIGF-1 treatment increased plasma IGF-1 levels 3-4 fold, reaching the values reported for term suckling piglets. In Experiment 1, rhIGF-1 treatment increased spleen and intestinal weights without affecting clinical outcomes like growth, blood biochemistry (except increased sodium and gamma-glutamyltransferase levels), hematology (e.g., red and white blood cell populations), glucose homeostasis (e.g., basal and glucose-stimulated insulin and glucose levels) or systemic immunity variables (e.g., T cell subsets, neutrophil phagocytosis, LPS stimulation, bacterial translocation to bone marrow). The rhIGF-1 treatment increased gut protein synthesis (+11%, p < 0.05) and reduced the combined incidence of all-cause mortality and severe necrotizing enterocolitis (NEC, p < 0.05), but had limited effects on intestinal morphology, cell proliferation, cell apoptosis, brush-border enzyme activities, permeability and levels of cytokines (IL-1β, IL-6, IL-8). In Experiment 2, rhIGF-1 treated pigs had reduced blood creatine kinase, creatinine, potassium and aspartate aminotransferase levels, with no effects on organ weights (except increased spleen weight), blood chemistry values, clinical variables or NEC.

CONCLUSION

Physiological elevation of systemic IGF-1 levels for 8 days after preterm birth increased intestinal weight and protein synthesis, spleen weight and potential overall viability of pigs, without any apparent negative effects on recorded clinical parameters. The results add further preclinical support for safety and efficacy of supplemental IGF-1 to hospitalized very preterm infants.

Insulin-Like Growth Factor 1 in the Preterm Rabbit Pup: Characterization of Cerebrovascular Maturation following Administration of Recombinant Human Insulin-Like Growth Factor 1/Insulin-Like Growth Factor 1-Binding Protein 3

Following preterm birth, serum levels of insulin-like growth factor 1 (IGF-1) decrease compared to corresponding in utero levels. A recent clinical trial indicated that supplementation with recombinant human (rh) IGF-1/rhIGF-binding protein 3 (rhIGF-1/rhIGFBP-3) prevents severe intraventricular hemorrhage (IVH) in extremely preterm infants. In a preterm rabbit pup model, we characterized endogenous serum and hepatic IGF-1, along with brain distribution of IGF-1 and IGF-1 receptor (IGF1R). We then evaluated the effects of rhIGF-1/rhIGFBP-3 on gene expression of regulators of cerebrovascular maturation and structure. Similar to preterm infants, serum IGF-1 concentrations decreased rapidly after preterm birth in the rabbit pup. Administration of rhIGF-1/rhIGFBP-3 restored in utero serum levels but was rapidly eliminated. Immunolabeled IGF1R was widely distributed in multiple brain regions, displaying an abundant density in the choroid plexus and sub-ependymal germinal zones. Increased IGF-1 immunoreactivity, distributed as IGF1R, was detected 4 h after rhIGF-1/rhIGFBP-3 administration. The rhIGF-1/rhIGFBP-3 treatment led to upregulation of choroid plexus genes involved in vascular maturation and structure, with corresponding protein translation for most of these genes. The preterm rabbit pup model is well suited for evaluation of IGF-1-based prevention of IVH. Administration of rhIGF-1/rhIGFBP-3 affects cerebrovascular maturation, suggesting a role for it in preventing preterm IVH.

Supplemental Insulin-Like Growth Factor-1 and Necrotizing Enterocolitis in Preterm Pigs

Background: Recombinant human IGF-1/binding protein-3 (rhIGF-1/BP-3) is currently tested as a therapy in preterm infants but possible effects on the gut, including necrotizing enterocolitis (NEC), have not been tested. The aim of this study was to evaluate if rhIGF-1/BP-3 supplementation in the first days after birth negatively affects clinical variables like growth, physical activity, blood chemistry and hematology and gut maturation (e.g., intestinal permeability, morphology, enzyme activities, cytokine levels, enterocyte proliferation, NEC lesions), using NEC-sensitive preterm pigs as a model for preterm infants. Methods: Preterm pigs were given twice daily subcutaneous injections of rhIGF-1/BP-3 or vehicle. Blood was collected for IGF-1 measurements and gut tissue for NEC evaluation and biochemical analyses on day 5. Results: Baseline circulating IGF-1 levels were low in preterm pigs compared with near-term pigs reared by their mother (<20 vs. 70 ng/ml). Injection with rhIGF-1/BP-3 resulted in increased plasma IGF-1 levels for up to 6 h after injection (>40 ng/mL). rhIGF-1/BP-3 treatment reduced the incidence of severe NEC lesions (7/24 vs.16/24, p = 0.01) and overall NEC severity (1.8 ± 0.2 vs. 2.6 ± 0.3, p < 0.05, with most lesions occurring in colon). In the small intestine, villi length (405 ± 25 vs. 345 ± 33 μm) and activities of the brush border peptidases aminopeptidase N and dipeptidylpeptidase IV were increased in rhIGF-1/BP-3 treated pigs, relative to control pigs (+31-44%, both p < 0.05). The treatment had no effects on body weight, blood chemistry or hematology, except for an increase in blood leucocyte and neutrophil counts (p < 0.05, i.e., reduced neonatal neutropenia). Likewise, rhIGF-1/BP-3 treatment did not affect intestinal tissue cytokine levels (IL-1β, IL-6, IL-8, TNFα,), enterocyte proliferation, goblet cell density, permeability or bacterial translocation to the bone marrow. Conclusion: Supplemental rhIGF-1/BP-3 did not negatively affect any of the measured variables of clinical status or gut maturation in preterm pigs. Longer-term safety and efficacy of exogenous rhIGF-1/BP-3 to support maturation of the gut and other critical organs in preterm newborns remain to be investigated in both pigs and infants.

Models of neurological disease (substance abuse): self-administration in monkeys

Drug self-administration is a procedure in which a subject performs a specified response that results in the delivery of a drug injection. This procedure is viewed as a relevant model for the study of human drug-taking behavior. Drug self-administration in primates has several characteristics that resemble drug-taking behavior in humans, and agents commonly abused by humans also generally maintain self-administration behavior in monkeys. Self-administration procedures allow for the study of a variety of drug properties. For instance, they can be used to investigate the abuse potential of new compounds and to study the effects of candidate medications for the treatment of drug addiction. These procedures can also be employed for examining drug reinforcement mechanisms. Described in this unit are procedures for studying intravenous drug self-administration in large primates, such as rhesus macaques, and smaller primates, such as squirrel monkeys.

Intravenous self-administration techniques in monkeys

Drug self-administration is a procedure in which a subject performs a response, called an operant, that results in the delivery of a drug injection. This procedure is viewed as a relevant model for the study of human drug-taking behavior. Drug self-administration in primates has several characteristics that resemble drug-taking behavior in humans, and drugs that are commonly abused by humans also typically maintain self-administration behavior in monkeys. Drug self-administration procedures allow for the study of a variety of drug properties. For instance, they are used to investigate the abuse potential of new compounds and to study the effects of candidate medications for the treatment of drug addiction. These procedures also can be used to study the process of drug reinforcement. This unit describes intravenous drug self-administration in large primates, such as rhesus macaques, and smaller primates, such as squirrel monkeys.

A multicentre longitudinal observational study of changes in self reported health status in people with Parkinson's disease left untreated at diagnosis

BACKGROUND

The issue of when to start treatment in Parkinson's disease (PD) remains controversial. Some favour treatment at diagnosis while others opt for a "wait and watch" policy. The effect of the latter policy on the self reported health status of people with PD is unknown.

AIMS

To record self reported health status through longitudinal use of a validated PD specific questionnaire (PDQ-39) in untreated PD patients in multiple centres in the UK. To compare patients who were left untreated with those who were offered treatment during follow-up.

METHODS

A multicentre, prospective, "real life" observational audit based study addressing patient reported outcomes in relation to self reported health status and other sociodemographic details.

RESULTS

198 untreated PD were assessed over a mean period of 18 months. During two follow-up assessments, the self reported health status scores in all eight domains of the PDQ-39 and the overall PDQ-39 summary index worsened significantly (p<0.01) in patients left untreated. In a comparative group in whom treatment was initiated at or soon after diagnosis, there was a trend towards improvement in self reported health status scores after treatment was started.

CONCLUSIONS

This study addresses for the first time self reported health status, an indicator of health related quality of life, in untreated PD. The findings may strengthen the call for re-evaluation of the policy to delay treatment in newly diagnosed patients with PD.

Discovery ofN-[(3R)-1-Azabicyclo[2.2.2]oct-3-yl]furo[2,3-c]pyridine-5-carboxamide, an Agonist of the α7 Nicotinic Acetylcholine Receptor, for the Potential Treatment of Cognitive Deficits in Schizophrenia: Synthesis and Structure−Activity Relationship

N-[(3R)-1-Azabicyclo[2.2.2]oct-3-yl]furo[2,3-c]pyridine-5-carboxamide (14, PHA-543,613), a novel agonist of the alpha7 neuronal nicotinic acetylcholine receptor (alpha7 nAChR), has been identified as a potential treatment of cognitive deficits in schizophrenia. Compound 14 is a potent and selective alpha7 nAChR agonist with an excellent in vitro profile. The compound is characterized by rapid brain penetration and high oral bioavailability in rat and demonstrates in vivo efficacy in auditory sensory gating and, in an in vivo model to assess cognitive performance, novel object recognition.

The dopamine D(1) receptor agonist SKF-82958 serves as a discriminative stimulus in the rat

We examined the discriminative stimulus effects of the high-efficacy dopamine D(1) receptor agonist (+/-)6-chloro-7, 8-dihydroxy-3-ally1-phenyl-2,3,4,5-tetrahydro-1H-3benzazepine++ + hydrobromide (SKF-82958) in rats trained to discriminate SKF-82958 (0.03 mg/kg) from vehicle in a two-lever food-reinforced drug discrimination task. SKF-82958 produced dose-related increases in responding to the SKF-82958 appropriate lever with full substitution occurring at the training dose. Pretreatment with the dopamine D(1)/D(5) receptor antagonist (-)-trans-6,7,7a,8,9, 13b-hexahydro-3-chloro-2hydroxy-N-methyl-5H-benzo-[d]naphtho -¿2, 1-b¿azepine (SCH-39166) (0.01 mg/kg) attenuated the discriminative stimulus effects of SKF-82958. Pretreatment with the dopamine D(2) receptor antagonist raclopride (0.03 mg/kg) had no effect. The high-efficacy dopamine D(1) receptor agonist R(+)6chloro-7, 8-dihydroxy-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrobromide (SKF-81297) fully substituted for SKF-82958, whereas the low-efficacy dopamine D(1) receptor agonist (+/-)1-phenyl-2,3,4, 5-tetrahydro-(1H)-3-benzazepine-7,8-diol hydrochloride (SKF-38393) produced only partial substitution. The dopamine D(2) receptor agonist trans-(+/-)-4,4a,5,6,7,8,8a, 9-octahydro-5-propyl-1H-propyl-1H-pyrazolo[3,4-g]quinoline dihydrochloride (quinpirole) and the indirect dopamine agonist cocaine did not substitute fully for the SKF-82958 discriminative stimulus cue. These results demonstrate that the high-efficacy dopamine D(1) receptor agonist SKF-82958 can serve as an effective discriminative stimulus in the rat, and that these effects are mediated by a dopamine D(1)-like receptor mechanism.

Heritability of MMPI Harris-Lingoes and Subtle-Obvious subscales in twins reared apart

A large sample of identical and fraternal twins who had been reared apart was used to examine the genetic and environmental architecture of the MMPI Subtle-Obvious and Harris-Lingoes subscales. Univariate genetic analyses indicated significant heritability for all 28 of the Harris-Lingoes subscales (estimates ranged from.23 to.61), all five Obvious subscales (estimates ranged from.37 to.56) and four of the five Subtle subscales (estimates ranged from.27 to.35). Two randomly constructed scales were analyzed as controls; neither of these scales showed significant heritability. Exploratory correlational findings suggested that three of the Wiener-Harmon Subtle subscales may tap aspects of psychological health, naivete, or repression. Ma-S may come closest to Wiener and Harmon s intent. Although they apparently diverge from their original purpose, it may be too early to abandon the low face valid items of the Subtle subscales.

Antisocial behavior, substance use, and somatization in families of adolescent drug abusers and adolescent controls

Symptoms of conduct disorder (CD), antisocial personality disorder (ASP), alcohol abuse, drug abuse, and somatization were tabulated for the families of 35 delinquent, substance-abusing (multiple-problem) adolescent male probands and 35 age-matched control males. Alcohol abuse, CD/ASP, and somatization were assessed with either the Diagnostic Interview Schedule (DIS) (for participants aged 18 and up) or the Diagnostic Interview for Children and Adolescents (DICA) (for participants aged 12 to 17). Drug abuse for all participants was assessed with the Substance Abuse Module (SAM) of the Comprehensive Interview for Diagnostic Evaluation (CIDE). As expected, proband groups had significantly more (p < .0001) CD/ASP, alcohol abuse, and drug abuse symptoms than control groups. A significant (p < .01) positive correlation among CD/ASP, alcohol abuse, and drug abuse was found for each group. Somatization was not differentially associated with proband status. It was concluded that identifying male multiple-problem youths also identifies families with a high incidence of similar problems.

p53 overexpression and downregulation of inter-alpha-inhibitor are associated with hyaluronidase enhancement of TNF cytotoxicity in L929 fibroblasts

Degradation of extracellular matrix by hyaluronidase increases murine L929 cell sensitivity to tumor necrosis factor (TNF) cytotoxicity. Seeding and culturing L929 cells onto the matrix of serum fetuin and the hyaluronate-binding inter-alpha-inhibitor resulted in inhibition of hyaluronidase-enhanced TNF killing, suggesting that the release of these proteins from hyaluronidase-degraded matrix confers cellular TNF susceptibility. Metabolic labeling studies showed that hyaluronidase mediated de novo protein synthesis and down regulated several proteins in L929 cells. Specifically, hyaluronidase upregulated p53 protein expression (>200%) but down regulated a p85 inter-alpha-inhibitor-like protein (>90%) in L929 cells, whereas it had no effect on the protein levels of ICH-1, Bcl-xL, Bcl-2, Fas ligand, CAS (cellular apoptosis susceptible protein), TIAR (an RNA-binding protein) and alpha-tubulin. Conceivably, hyaluronidase enhancement of TNF sensitivity in L929 cells is p53-dependent and the matrix inter-alpha-inhibitor contributes a protective role against TNF cytotoxicity.

JL13, a pyridobenzoxazepine compound with potential atypical antipsychotic activity: a review of its behavioural properties

The search for an improved clozapine-like compound has resulted in the selection of a new molecule: JL13 (5-(4-methylpiperazin-1-yl)-8-chloro-pyrido[2,3-b][1,5] benzoxazepine fumarate). Like clozapine, JL13 did not antagonize apomorphine-induced stereotypy and did not produce catalepsy but antagonized apomorphine-induced climbing in rodents (ID50 = 3.9 mg kg-1 s.c.). It was inactive against d-amphetamine-induced stereotypy but antagonized d-amphetamine-induced hyperactivity in the mouse (ID50 = 4.4 mg kg-1 i.p.). JL13, like clozapine, was able to antagonize (+/-)-DOI-induced head-twitches in the mouse (ID50 = 2.0 mg kg-1 i.p.). In the open-field test in the rat and forced swimming test in the mouse a high similarity was noted between the two drugs in the same range of doses. In a complex temporal regulation schedule in the dog, JL13 showed a high resemblance with clozapine without inducing sialorrhea, palpebral ptosis or any significant motor side effects. In rats trained to discriminate clozapine, JL13 (10 mg kg-1 i.p.) induced a high level of generalization (70%) to clozapine. In a drug discrimination procedure in the squirrel monkey, JL13 (3-10 mg kg-1 i.m.) produced a full substitution of clozapine. On the basis of these preclinical data, it is thus predicted that JL13 would be a promising atypical antipsychotic drug.

Genetic and environmental architecture of human aggression

A meta-analysis was performed on data from 24 genetically informative studies by using various personality measures of aggression. There was a strong overall genetic effect that may account for up to 50% of the variance in aggression. This effect was not attributed to methodological inadequacies in the twin or adoption designs. Age differences were important. Self-report and parental ratings showed genes and the family environment to be important in youth; the influence of genes increased but that of family environment decreased at later ages. Observational ratings of laboratory behavior found no evidence for heritability and a very strong family environment effect. Given that almost all substantive conclusions about the genetics of personality have been drawn from self or parental reports, this last finding has obvious and important implications for both aggression research in particular and personality research.

Characterization of an insulin-like growth factor (IGF) receptor and the insulin-like effects of IGF-1 in the bony fish, Lates calcarifer

The present work is part of a broad phylogenetic study of the insulin superfamily of peptides in lower vertebrates. In the bony fish barramundi (Lates calcarifer), the presence of IGF receptors were investigated in the liver by means of competitive binding studies. The results suggested the presence of a type 1-like but no type 2-like IGF receptor. We also demonstrated insulin-like effects of intraperitoneally injected recombinant human (rh)-IGF-1 in barramundi with rh-IGF-1 and rh-insulin showing similar effects with respect to induction of hypoglycemia and stimulation of incorporation of [14C]-glucose into muscle glycogen.

Heritability of MMPI personality indicators of psychopathology in twins reared apart

This report presents Minnesota Multiphasic Personality Inventory (MMPI) findings from the Minnesota Study of Twins Reared Apart. Data from 65 unique pairs of monozygotic twins reared apart (MZA) and 54 unique pairs of dizygotic twins reared apart (DZA) were analyzed. As in other results from this sample, MZA twins evidenced substantial similarity, highlighting the influence of shared genes. Biometric modeling yielded estimates of heritability for the MMPI's standard validity and clinical scales and for the Wiggins content scales ranging from .26 to .62 (M = .44), echoing previous findings from the twin and adoption literature on personality. The pattern of MZA and DZA correlations suggested nonadditive genetic effects for 3 MMPI scales. Multivariate profile analyses also suggested genetic influence on both profile elevation and shape.

Genetic and environmental architecture of human aggression

A meta-analysis was performed on data from 24 genetically informative studies by using various personality measures of aggression. There was a strong overall genetic effect that may account for up to 50% of the variance in aggression. This effect was not attributed to methodological inadequacies in the twin or adoption designs. Age differences were important. Self-report and parental ratings showed genes and the family environment to be important in youth; the influence of genes increased but that of family environment decreased at later ages. Observational ratings of laboratory behavior found no evidence for heritability and a very strong family environment effect. Given that almost all substantive conclusions about the genetics of personality have been drawn from self or parental reports, this last finding has obvious and important implications for both aggression research in particular and personality research.

Heritability of MMPI personality indicators of psychopathology in twins reared apart

This report presents Minnesota Multiphasic Personality Inventory (MMPI) findings from the Minnesota Study of Twins Reared Apart. Data from 65 unique pairs of monozygotic twins reared apart (MZA) and 54 unique pairs of dizygotic twins reared apart (DZA) were analyzed. As in other results from this sample, MZA twins evidenced substantial similarity, highlighting the influence of shared genes. Biometric modeling yielded estimates of heritability for the MMPI's standard validity and clinical scales and for the Wiggins content scales ranging from .26 to .62 (M = .44), echoing previous findings from the twin and adoption literature on personality. The pattern of MZA and DZA correlations suggested nonadditive genetic effects for 3 MMPI scales. Multivariate profile analyses also suggested genetic influence on both profile elevation and shape.

The incidence of antibody formation to OKT3 consequent to its use in organ transplantation

Enzyme-linked immunosorbent assays were performed on 12,133 serum samples to determine the incidence of anti-OKT3 antibody formation among transplant recipients who had received OKT3 for rejection treatment or prophylaxis. High anti-OKT3 antibody titers (> or = 1:1000) were detected in 5.8% of samples drawn 2 to 8 weeks following initiation of OKT3 therapy. The frequency of high titers differed by organ (6.9%, 2.7%, and 5.3% for kidney, heart, and liver, respectively; P < 0.001) and by sampling times (P < 0.001). The highest frequency of positive titers was obtained in samples obtained between 2 and 4 weeks following the initiation of OKT3. For all transplant recipients and for kidney recipients alone, multivariate logistic regression showed that the risk of high anti-OKT3 titers varied significantly at 2 to 4 weeks and at 4 to 6 weeks (but not at 6 to 8 weeks) with age (the youngest patients had the highest incidence, with a steady decline after age 30; P < 0.05), course of therapy (lowest frequencies followed a first course of OKT3; P < 0.001), and transplant number (lowest frequencies followed a first transplant; P < 0.01). Analyses of a set of patients on whom immunosuppressive regimen information was available indicated that prophylactic or maintenance treatment with CsA was associated with a significantly lower frequency of high-titer anti-OKT3 antibodies than was therapy without CsA (P < 0.001). In conclusion, this series provides confirming evidence that high-titer anti-OKT3 antibodies, which are of concern whenever retreatment with OKT3 is contemplated, occur in a low percentage of patients and are associated with such factors as age, previous transplantation or courses of therapy with OKT3, and treatment with CsA.

A twin study of non-alcohol substance abuse

Except for alcohol abuse, little is known about the familial aggregation for substance abuse. Here we report twin resemblance for non-alcohol substance use in the Washington University Twin Series, wherein probands were identified by consecutive admission to psychiatric facilities in the St. Louis area. A 5-point substance abuse scale was constructed with values anchored by never used drugs (1) to drug dependence (5). Year of birth was the most powerful predictor of drug use--younger twins scored far higher than older twins. Either heritability or common environment had to be included in the regression model to avoid a significant drop in explained variance, but which was more important could not be resolved. The correlation for identical twins exceeded that for fraternal twins, suggesting the possibility of a heritable factor.

Genetic association study in psychiatry: analytical evaluation and a recommendation

Recent analysis of the candidate gene, association study for psychiatric disorders have concluded that most statistically significant results are likely to be false positives because there are a large number of potential candidate loci and a low a priori probability that a given candidate locus will in fact be trait relevant. Hence, it was recommended that the alpha level (P level) be lowered for association studies. The present study demonstrates that lowering the alpha level to some fixed, predetermined value is not a recommended strategy. Rather, the probability of false positives (and false negatives) depends on such parameters as the prevalence of the disorder, the prevalence of the genotypes at the candidate locus, and the relative risk. In some areas of the parameter space, the adjustment to alpha may be modest. In other areas, however, even the requirement of one or more independent replications of the original results gives false positive rates exceeding 80% or 90%. Hence, the P levels required to minimize false positives may have to be changed from one statistical test to another even within the same study. A procedure for adjusting the probability level for a test of association between genotypes and a disorder is given.

Personality and psychopathology: genetic perspectives

Genetic factors exert an important influence on adult personality traits, accounting for anywhere between 30% and 60% of the variance. Heredity is also important for most forms of psychopathology and plays a major role in several theories that relate personality to psychopathology. Despite this, there has been surprisingly little multivariate genetic research reported on joint analyses of personality and psychopathology. The small amount of available data suggests that genes may account for over 50% of the observed correlation between neuroticism and state symptoms of anxiety and depression. The mechanisms behind such strong genetic correlations are crucial for understanding the causal relationship between a personality trait and a disorder because genetically influenced biological systems may operate as exogenous "third-party" factors that are responsible for what appear to be phenotypic cause-effect relationships. We illustrate how recent analytical advances in behavior genetics can use multivariate family data to address questions about the causal role of personality in psychopathology.

Personality and psychopathology: genetic perspectives

Genetic factors exert an important influence on adult personality traits, accounting for anywhere between 30% and 60% of the variance. Heredity is also important for most forms of psychopathology and plays a major role in several theories that relate personality to psychopathology. Despite this, there has been surprisingly little multivariate genetic research reported on joint analyses of personality and psychopathology. The small amount of available data suggests that genes may account for over 50% of the observed correlation between neuroticism and state symptoms of anxiety and depression. The mechanisms behind such strong genetic correlations are crucial for understanding the causal relationship between a personality trait and a disorder because genetically influenced biological systems may operate as exogenous "third-party" factors that are responsible for what appear to be phenotypic cause-effect relationships. We illustrate how recent analytical advances in behavior genetics can use multivariate family data to address questions about the causal role of personality in psychopathology.

Path analysis and sib-pair linkage

When the distance between linked loci is expressed in terms of the correlation between the identity-by-descent (idb) values of the loci, then a path model may be used to order loci with data on sib-pairs and their parents. The relationship between the recombination fraction and the correlation coefficient is developed and a method for fitting a covariance matrix predicted by a specific ordering of loci to an observed covariance matrix is proposed.

Identifying children in the Colorado Adoption Project at risk for conduct disorder

Clustering techniques were used to identify a subsample of young adopted and nonadopted children in the Colorado Adoption Project at risk for conduct disorder. Although data from both boys and girls were analyzed, a cluster of girls large enough for subsequent statistical analysis could not be identified; therefore, results are reported for boys only. Identifying measures were selected based on the DSM-III-R diagnostic criteria. Cluster analyses confirmed the existence of a small group of boys who appeared to be significantly at risk. Subsequent parental and teacher ratings of these children verified the stability over time of the classification. The poor conduct group was significantly associated with difficult temperament in infancy, with poor conduct on the part of parents when they were youths, and with high achievement orientation in the home environment.

Simulated twin data on substance abuse

Twin data were simulated for use of a new illegal substance. The twin cohort was "measured" yearly at 10 time intervals during the diffusion of the substance throughout the nation. The models used to generate the data are discussed.

Twin imitation for antisocial behavior: implications for genetic and family environment research

When twin pairs influence each other's behavior, observed variance is greater for MZ twins than for DZ twins under at least 1 of 2 conditions: (a) the trait has some heritability and (b) MZ twins influence each other more than do DZ twins. Applied to a trait that has an underlying continuous distribution but is measured as a dichotomy, the presence of reciprocal twin influence predicts that if the base rate for the trait is not exactly 50%, then the prevalence of the trait should differ in MZ and DZ twin pairs. This prediction held for registered criminality in a large twin cohort. Methods of analysis that permit reciprocal twin interaction not only provide better statistical fits to the data but also yield estimates of heritability that agree with adoption data. The results suggest that the genetic influence on registered criminality may be more modest than previously thought.

Twin imitation for antisocial behavior: Implications for genetic and family environment research

When twin pairs influence each other's behavior, observed variance is greater for MZ twins than for DZ twins under at least 1 of 2 conditions: (a) the trait has some heritability and (b) MZ twins influence each other more than do DZ twins. Applied to a trait that has an underlying continuous distribution but is measured as a dichotomy, the presence of reciprocal twin influence predicts that if the base rate for the trait is not exactly 50%, then the prevalence of the trait should differ in MZ and DZ twin pairs. This prediction held for registered criminality in a large twin cohort. Methods of analysis that permit reciprocal twin interaction not only provide better statistical fits to the data but also yield estimates of heritability that agree with adoption data. The results suggest that the genetic influence on registered criminality may be more modest than previously thought.

Parent-offspring and sibling adoption analyses of parental ratings of temperament in infancy and childhood

A first step toward understanding the etiology of personality is to investigate the relative impact of genetic and environmental factors using twin and adoption designs. Twin studies of infants and young children indicate substantial genetic influence for parental ratings of temperament in the preschool years. Adoption studies, however, have not previously been reported during the early years of life. We present parent-offspring comparisons for temperament (emotionality, activity, sociability, and impulsivity) for adopted and nonadopted children yearly from 1 to 7 years of age and their biological, adoptive, and nonadoptive parents. Also presented are correlations for adoptive and nonadoptive siblings when each child was 1, 2, 3, and 4 years of age. In contrast with twin results, little evidence is found for genetic influence. The average correlation between biological parents and their adopted-away children for data averaged over the 7 years is only .03. Similarly, the average parent-offspring correlation in nonadoptive families (.08) is no greater than in adoptive families (.12). Results for nonadoptive and adoptive siblings also indicate little genetic influence. The difference between the twin and adoption results may be due to environmental effects or to nonadditive genetic variance.

Codistribution of a sensory gating deficit and schizophrenia in multi-affected families

Because the clinical diagnosis of schizophrenia has not generally been an adequate phenotypic marker to detect the genes that convey risk for schizophrenia, efforts have been directed toward the identification of more elementary neuronal dysfunctions in schizophrenic patients and their families. Psychophysiological studies of sensory gating and selective attention suggest that defects in these brain functions are present in schizophrenic patients and some of their relatives. This study examines one of these defects in sensory gating, failure to suppress the P50 evoked response to repeated auditory stimuli. Six pedigrees, chosen because of the presence of large sibships containing several cases of schizophrenia, were studied. A mathematical model was developed to assess the familial association of the P50 defect with schizophrenia. The model preserves the quantitative nature of the data and is suitable for use in a sample with small numbers of pedigrees comprising many individuals. It is thus suitable for the evaluation of putative phenotypes in families to be studied by linkage analysis with polymorphic genetic markers. The results suggest that the P50 defect is familially associated with schizophrenia.

Linkage analysis of quantitative traits: increased power by using selected samples

Although a number of methods have been developed for linkage analysis of quantitative traits, power is relatively poor unless there is a single major locus of very large effect. Here it is demonstrated that the use of selected samples (i.e., ascertainment of a proband with an extreme score on the quantitative measure) can dramatically increase power, especially when proband selection is performed on the tail of a distribution with an infrequent recessive gene. Depending on gene action and allele frequency, selected samples permit detection of a major locus that accounts for as little as 10%-20% of the phenotypic variation. The judicious use of selected samples can make an appreciable difference in the feasibility of linkage studies for quantitative traits.