Cerebral ventricle-brain ratio in monozygotic twins discordant and concordant for schizophrenia

The influence of tetrapeptide tuftsin (Tyr-Lys-Pro-Arg) on learning, exploratory activity, emotional behavior, and hypothalamic monoamine content was studied in Wistar rats with different resistance to stress induced by acoustic stimuli. Positive effects of taftsin were more pronounced in low-resistant rats. Administration of taftsin induced in these animals a significant increase in reactivity to stimuli of different modalities, the open-field exploratory activity, rate of alimentary conditioning and its modification in emotionally negative situation. Biochemical examinations showed that in rats with high resistance to stress taftsin administration led to a decrease in hypothalamic noradrenaline level and increase in dopamine and serotonin levels. On the contrary, in low-resistant animals taftsin increased the level of noradrenaline and decreased that of dopamine, serotonin, and 5-hydroxyindoleacetic acid. It is suggested that different behavioral effects of taftsin in stress-resistant and nonresistant rats are caused by its different influence on hypothalamic biogenic amines.     

Olfactory function in monozygotic twins discordant for schizophrenia

Microtubule disassembly is commonly believed to be a process of endwise tubulin dimer release. The present study demonstrates by video interference contrast microscopy that Escherichia coli lipopolysaccharide (LPS) caused microtubule disassembly in vitro by both endwise shortening and fragmentation. In contrast, the microtubules were only shortened from their ends in the presence of DNA, used as another example of a macromolecular microtubule effector. LPS-caused microtubule fragmentation was confirmed by transmission electron microscopy. Because of its ability to induce both fragmentation and endwise shortening, LPS, which is involved in sepsis pathogenesis, has to be regarded as a highly active microtubule-destabilizing agent.     

Genomic discordance between monozygotic twins discordant for schizophrenia

Based on volume-flow relationships, CNS agents that are highly lipid soluble (log octanol-water partition coefficient > 2) are expected to have equilibration half-times (T1/2 kE0) that are proportional to brain solubility. Propofol, the most lipophilic anaesthetic in clinical use, has T1/2 kE0 values of 1.7 and 2.9 min in rats and humans, respectively, compared with an expected value of at least 8 min. As a first step in exploring this discrepancy between observed and predicted values, we determined the steady state brain:plasma and brain:blood partition coefficients in rats after a 4-h infusion of propofol. Brain:plasma and brain:blood partition coefficients were 8.2 (SD 1.6) and 3.0 (0.5), respectively. T1/2 kE0 predictions based on brain: blood partitioning in rats are more in agreement with the observed equilibration half-time, suggesting that drug bound to the formed elements of blood participates in the uptake and transfer of propofol to its effect site.     

Neurocognitive function in monozygotic twins discordant for combat exposure: Relationship to posttraumatic stress disorder.

Neuropsychological deficits have been reported among trauma survivors with posttraumatic stress disorder (PTSD). It is often assumed that these cognitive difficulties are toxic consequences of trauma exposure. Alternatively, they may reflect preexisting characteristics that contribute to the likelihood of developing PTSD. To address this possibility, the authors evaluated cognitive performance in monozygotic twin pairs who were discordant for combat exposure. Pairs were grouped according to whether the combat-exposed brother developed PTSD. The combat-unexposed cotwins of combat veterans with PTSD largely displayed the same performance as their brothers, which was significantly lower than that of non-PTSD combat veterans and their brothers. The results support the notion that specific domains of cognitive function may serve as premorbid risk or protective factors in PTSD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Monozygotic twins discordant for schizophrenia: A review.

Describes 3 approaches using monozygotic twins discordant for schizophrenia. It is noted that comparisons of discordant with concordant pairs have yielded conflicting results concerning the possibility of both genetic and environmentally induced forms of schizophrenia. Life history comparisons of schizophrenics with their nonschizophrenic co-twins have revealed consistent early differences in personality and parental treatment; investigators disagree, however, on the relationship of birth weight to schizophrenic development. Relatively few studies have been done of concordance for personality or performance traits among monozygotic twins discordant for schizophrenic diagnosis. It is suggested that this 3rd type of research holds great promise for identifying fundamental manifestations of the schizophrenic genotype, that higher female concordance rates make female discordance worthy of greater attention, and that investigations of environmental influences on the development of schizophrenia neglect less the possible positive influences which may buffer against schizophrenic breakdown. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Multitask analysis of cerebral hemisphere specialization in monozygotic twins discordant for handedness

Associations between neighborhood characteristics and adjustment of 168 urban fifth-grade children were explored. High neighborhood risk was associated with parent and teacher reports of child misconduct, and with parent and child reports of child psychological distress, while child and parent perceptions of neighborhood dangers appeared to mediate these associations. Specific neighborhood aspects were also related to child adjustment: higher violent crime rates with higher child misconduct rates, and lower neighborhood incomes with greater child psychological distress. Implications for research and intervention are discussed.     

Normal personality characteristics in identical twins discordant for schizophrenia.

The authors examined normal personality characteristics of monozygotic (MZ) twins discordant for schizophrenia. Twenty pairs of discordant twins were analyzed; 11 pairs of MZ twins concordant for schizophrenia served as a comparison group. Personality was assessed using the Multidimensional Personality Questionnaire (MPQ; A. Tellegen, 1995). Among discordant twin pairs, twins with schizophrenia were more deviant than normal co-twins on all but 4 of the MPQ's scales. Analysis of MZ twin correlations among the discordant twin pairs revealed substantial erosion of personality similarity as compared to normal individuals, although a cluster of scales related to Constraint/Psychoticism showed significant correlations. The results highlight striking personality divergence related to nonshared environmental influences. It is not possible to determine the point at which the twins diverged, although previous findings from this sample suggest that the observed personality differences may reflect effects of schizophrenia on normal personality. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Low birth weight is associated with non-insulin-dependent diabetes mellitus in discordant monozygotic and dizygotic twins

Previous studies have demonstrated an association between low weight at birth and risk of later development of non-insulin dependent diabetes mellitus (NIDDM). It is unknown whether this association may be due to an impact of intrauterine malnutrition per se, or whether it may be due to a coincidence between the putative "NIDDM susceptibility genotype" and a genetically determined low weight at birth. We traced original midwife birthweight record determinations in a group of monozygotic (n = 14 pairs) and dizygotic (n = 14 pairs) twins who phenotypically appeared discordant for NIDDM at a mean age of 67 and 64 years respectively. Birthweights were lower in the NIDDM twins compared with both their identical and non-identical non-diabetic co-twins respectively (p < 0.02 both). Using a similar approach in twin pairs discordant for impaired glucose tolerance (IGT) per se, no significantly decreased birthweight was detected in the IGT twins compared with their non-diabetic co-twins. However, when a larger group of twins with different glucose tolerances were considered, birthweights were lower in twins with abnormal glucose tolerance including both NIDDM and IGT. Furthermore, the twins with the lowest birthweights among the two co-twins had the highest plasma glucose concentrations 120 min after the 75 g oral glucose load (n = 86 pairs, p = 0.02). The study supports the hypothesis that low birthweight and a non-genetically determined intrauterine component such af malnutrition may play a role for the development of NIDDM in twins.     

Analyses of craniofacial and dental morphology in monozygotic twins discordant for cleft lip and unilateral cleft lip and palate

AIMS: To compare the efficiency of flow cytometry and computed image cytometry; and to see if a reliable set of guidelines regarding interpretation of histograms could be drawn up. METHODS: The two methods were applied to a series of 111 formalin fixed renal cell carcinomas. Data generated by both methods were compared. RESULTS: The methods agreed in 85 cases. Hypodiploidy was detected by computed image cytometry in seven cases in which flow cytometry had shown only an aneuploid peak. Aneuploidy in seven in which the corresponding flow cytometry histogram was diploid. There was an overlap in the second peak proportions on flow cytometry histograms between those classed as diploid or tetraploid by computed image cytometry. In six cases the flow cytometry histograms had unacceptably high coefficients of variation and in all of these cases computed image cytometry demonstrated aneuploidy. CONCLUSIONS: Computed image cytometry is particularly useful for clarifying difficult areas in flow histograms--specifically, high coefficients of variation, high G2M phase, as well as possible near diploid aneuploidy and hypodiploidy.     

Neuropsychological and psychosocial effects of the FMR-1 full mutation: Case report of monozygotic twins discordant for the fragile X syndrome.

An extensive evaluation was conducted with 16-yr-old monozygotic twins concordant for the fragile X full mutation but discordant for mental retardation. The clearly affected twin had an IQ score of 47; 77% of her neuropsychological z scores were at least 2 SDs below average. Her sister had an IQ score of 105 and average neuropsychological performance. However, each girl demonstrated relative verbal strengths and visual-spatial weaknesses. Their parents rated each girl as having significant problems with attention, conduct, anxiety-withdrawal, and hyperactivity. The girls did not rate themselves as having significant anxiety. These findings are consistent with group data on females with fragile X and demonstrate the wide range of effects associated with the fragile X full mutation. This case report implicates the importance of a psychosocial phenotype of fragile X independent of cognitive ability level. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Lifetime exercise and disk degeneration: an MRI study of monozygotic twins

Participation in some competitive sports has been shown to increase disk degeneration; however, the long-term effects of recreational physical activities are unclear. We investigated the effects of endurance exercise and power sports on disk degeneration in monozygotic male twins with contrasting lifetime exercise histories. The effects of endurance exercise were studied in 22 discordant twin pairs (mean lifetime frequencies of 3.9 vs 1.1 times/wk), and the effects of power sports were investigated in 12 discordant pairs (2,300 vs 200 h of weightlifting). The age range of the twins was from 35 to 69 yr. No differences in MRI findings between co-twins discordant for endurance exercise were found at any of the spinal regions. Subjects with more power sport involvement had greater disk degeneration in the T6-T12 region (P < 0.03), but similar findings were not present in the lumbar spine. Controlling for recalled back injuries, occupational loading, smoking, and driving did not significantly affect the results. No signs of beneficial or harmful effects of lifetime endurance exercise on disk degeneration were seen. Increased power sport participation was associated with slightly greater disk degeneration in the lower thoracic spine, but not in the lumbar spine.     

Genetic loadings in schizophrenia: a dermatoglyphic study

Finger and palmar dermatoglyphics of 120 male and 120 female schizophrenics with and without a family history of schizophrenia in first-degree relatives were studied in the northwestern part of India. Patients were selected according to specific diagnostic criteria. Significant dermatoglyphic differences were observed for fingerprint patterns, total finger ridge counts and 'atd' angle between the schizophrenics with and those without a positive family history of schizophrenia, suggesting a strong "genetic loading" (i.e., hereditary factors) in familial cases of schizophrenia. Dermatoglyphic features of isolated schizophrenics also significantly differed from those of controls, thus indicating the involvement of genetic factors in the etiology of schizophrenia.     

Continued impairment in persons at risk for bipolar affective disorder: Results of a 19-month follow-up study.

Conducted a 19-mo follow-up study of 45 undergraduates identified as being at risk for bipolar affective disorder by the General Behavior Inventory (GBI) by the authors and colleagues (see record 1982-01362-001). These Ss and 64 control undergraduates completed brief inventories reflecting their psychological impairment over the follow-up period. Overall, GBI cases continued to exhibit significant impairment relative to controls. Two cases had been hospitalized for major depressive episodes following suicide attempts. Significantly higher proportions of GBI cases (a) were referred for treatment by family or friends, (b) reported frequent suicidal ideation, and (c) frequently considered seeking treatment. (7 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nicotine and familial vulnerability to schizophrenia: A discordant twin study.

Tobacco use is significantly associated with schizophrenia. However, it is not clear if smoking is associated with the illness itself, treatment, or underlying vulnerability to the disease. Smoking was studied in a sample of schizophrenic probands (n = 24), their unaffected co-twins (n = 24), and controls (n = 3,347). Unaffected co-twins had higher rates of daily smoking than controls. Probands and co-twins were more frequently unsuccessful in attempts to quit than controls. Probands reported shaky hands and depression following smoking cessation more often than controls, whereas unaffected co-twins reported difficulty concentrating, drowsiness, nervousness, and headache following smoking cessation more often than controls. Results are consistent with the hypothesis that nicotine use is influenced by familial vulnerability to schizophrenia, not just clinical schizophrenia per se. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Are the brains of monozygotic twins similar? A three-dimensional MR study

PURPOSE: The role of genetic mechanisms and the influence of environmental events in human brain development have been difficult to evaluate. The purpose of this study was to compare the cerebral cortical morphology and midline structures of monozygotic twin pairs using MR imaging. METHODS: Six observers, blinded to twin pairings, evaluated the 3-D renderings of the cortical surface and midline structures from MR images of seven monozygotic twin pairs. A morphometric analysis of the corpus callosum and of the distance between the anterior and posterior commissures was also performed. RESULTS: Despite surprising anatomic differences, the brains of the twin pairs were similar enough to enable the observers to distinguish twin pairs from unrelated subjects. Five of six observers correctly identified the brains of all seven twin pairs; the remaining observer failed to make a correct match in only one of seven pairs. Three of six observers identified the midline sagittal images of the related twins in all seven pairs, and the other three identified the related midline sagittal images in five of seven pairs. The results were statistically significant. CONCLUSION: Although the observed differences in morphologic characteristics between twins necessarily reflect nongenetic influences, the cortical patterns and midline structures of monozygotic twins probably are genetically similar.     

Sex differences in neuropsychological performance and social functioning in schizophrenia and bipolar disorder.

Objective: To investigate sex differences in neurocognition and social functioning in schizophrenia and bipolar disorder and the possible role of sex as a moderator of this relationship. Method: Participants with schizophrenia (60 women/94 men), bipolar I disorder (55 women/51 men), and healthy controls (158 women/182 men) were assessed with an extensive neuropsychological test battery and a social functioning questionnaire. Results: We found significant main effects of sex for neuropsychological tests (p