The sympathetic nervous system response to a Continuous Performance Task.

A Continuous Performance Task is an example of a mental stressor which requires vigilance, attention, and effort. We hypothesized that a sympathetic nervous system response would be evident from a resting baseline period to this attention test, and explored if physiological measures were correlated to state and trait anxiety, perceived stress, mindfulness, and performance on the task. In 20 undergraduates, blood pressure and skin conductance increased due to the attention test but heart rate variability did not change. The physiological variables did not correlate to psychological variables; there was a trend of higher perceived stress correlating to lower foil accuracy rate ( p = 0.09). ClinicalTrials.gov ID: NCT06098352.

Volume of the thalamus and hypothalamus in the Ts1Rhr and Ms1Rhr mouse models relevant to Down syndrome.

A variety of mouse models for Down syndrome (Trisomy 21) have been created to test hypotheses about the correlation of phenotypes to gene content and copy number. Ts1Rhr mice are trisomic for a region on mouse chromosome 16 that is homologous to 5.3 Mb of human chromosome 21. Ms1Rhr mice are monosomic for this region. Magnetic Resonance Imaging (MRI) has revealed characteristic volumetric changes in the brains of humans with Down syndrome such as reductions in the cerebellum, hippocampus, and brain stem, and increases in the ventricles and thalamus. We used MRI with region of interest analysis to measure the volume of the thalamus and hypothalamus in Ts1Rhr, Ms1Rhr, and euploid control mice (n = 10-11 per group). Ts1Rhr mice had a 6.6% reduction and Ms1Rhr mice had an 8.2% reduction in the volume of the thalamus. Ts1Rhr and Ms1Rhr hypothalamic volumes were equivalent to controls. Conflicting data in mouse models show a lack of clarity on causative roles of regions homologous to human chromosome 21 in phenotypes related to the thalamus and hypothalamus in Down syndrome.

Effect of Seminar on Compassion on student self-compassion, mindfulness and well-being: A randomized controlled trial.

OBJECTIVE: Mindfulness-based interventions have been shown to have psychological benefits in college students. We explored the effects of an academic Seminar on Compassion on student psychological health. PARTICIPANTS: Forty-one participants (14 male, 27 female, mean age 19.8 ± 1.4 years) were assessed pre- and post- spring semesters 2013 and 2014. METHODS: Students were randomized to the Seminar on Compassion or a wait-list control group. Participants completed self-report measures on anxiety, depression, perceived stress, self-compassion, compassion and mindfulness. Salivary alpha-amylase was also assessed. RESULTS: At baseline, self-compassion and mindfulness were negatively correlated with depression, anxiety, and perceived stress. There were significant changes between the intervention and control group from Time 1 to Time 2 in mindfulness, self-compassion, compassion, and salivary alpha-amylase; however, there were no significant changes in depression, anxiety, and perceived stress. CONCLUSIONS: The course was effective in increasing mindfulness, self-compassion and compassion, and decreasing a salivary marker of stress.

Impact of Experiential Neuroscience of Meditation Course on Attitudes Toward Meditation and Science.

An interdisciplinary, intensive, and experiential course on Neuroscience of Meditation was designed to fulfill a general education science requirement. Class activities included lecture, class discussion of the textbook and scholarly articles, laboratory experimentation, and practicing 15 different forms of meditation. Laboratory investigations included sheep brain dissection, physiological measurements of the autonomic nervous system, electroencephalogram, salivary enzyme assays, attention testing, and psychological questionnaires. The Determinants of Meditation Practice Inventory (DMPI) and My Attitude Toward Science (MATS) scales were administered at the beginning and conclusion of the course; barriers to meditation were reduced and positive attitudes toward school science were increased. Comments on course evaluations praised this incorporation of contemplative pedagogy into a neuroscience course.

Measuring Salivary Alpha-Amylase in the Undergraduate Neuroscience Laboratory.

Undergraduate courses in biopsychology, neuroscience, and physiology often include laboratory exercises that examine responses to stimulation of the sympathetic nervous system with measurements of heart rate, blood pressure, or galvanic skin levels (sweat response). A newer bioindicator of the sympathetic nervous system is salivary alpha-amylase (sAA) measured with a colorimetic enzyme assay. Undergraduate students successfully measured a rise in sAA due to the stress of giving a class presentation (n=13). Students were enthusiastic to measure a physiological response to a real-life anxiety-producing situation. We describe potential difficulties in the assay and our adaptations to the manufacturer's protocol to make it more feasible in the undergraduate setting.

Sex differences in improved efficacy of doxorubicin chemotherapy in Cbr1+/- mice.

The anthracycline chemotherapeutic agent doxorubicin is converted by the enzyme carbonyl reductase 1 (CBR1) into its cardiotoxic metabolite doxorubicinol. Cbr1+/- mice have been shown to be protected from doxorubicin-induced cardiotoxicity, and the inhibition of CBR1 activity may be a useful means of ameliorating the side effects of doxorubicin in patients undergoing chemotherapy. Because reduced conversion to doxorubicinol increases circulating levels of the more effective parent drug doxorubicin, it was hypothesized that therapeutic efficacy against tumors might also be enhanced. Cbr1+/- mice were bred to mice transgenic for the polyomavirus middle T antigen (PyVT) to create offspring with palpable mammary tumors. Latency to initial tumor formation was similar in Cbr1+/- and Cbr1+/+ animals. Tumor regression was improved in Cbr1+/- animals, but only in male mice. Western blotting showed a marked sex difference in protein levels, with a much higher expression of Cbr1 in the female kidney and liver. Thus, the combined effects of a naturally low expression and the heterozygous Cbr1 null allele seem to have enhanced tumor regression in Cbr1+/- males. Future efforts to design a clinical CBR1 inhibitor to protect patients from the cardiac side effects of doxorubicin treatment should evaluate the effect of sex on anticancer efficacy.

Bone density phenotypes in mice aneuploid for the Down syndrome critical region.

Down syndrome (trisomy 21) is associated with reduced bone density in humans, but it is unclear whether this is due to specific effects of chromosome 21 genes or lifestyle factors. Mouse models with aneuploidy of segments of mouse chromosome 16 that are homologous to human chromosome 21 can be used to elucidate the mechanism by which Down syndrome phenotypes arise. Ts1Rhr and Ms1Rhr mice are trisomic and monosomic, respectively, for the hypothesized "Down syndrome critical region" containing approximately 33 genes. We assessed the skeletons of these mice from 3 to 16 weeks of age using dual X-ray absorptiometry. Ts1Rhr mice were unexpectedly similar to normal controls, showing that a larger region of trisomy is necessary to recapitulate the Down syndrome phenotype. Ms1Rhr mice, in contrast, showed decreases in weight, bone mineral content, bone mineral density, and bone area from weaning to adulthood. Regional bone density was also decreased in the femur, tibia, and lower lumbar spine. The microarchitecture of 3 week old Ms1Rhr femurs was then analyzed using µCT. Volumetric density, total tissue volume, bone volume, and bone fraction were all reduced in both cortical and trabecular bone. Ms1Rhr trabeculae were thinner and had decreased connectivity. A 31.5% reduction in the level of insulin-like growth factor I in the serum was found, and we hypothesize that this is responsible for the bone density phenotype. We discuss bone-related genes in the region and propose that humans with distal chromosome 21 deletions may exhibit reduced bone density.

The role of GH/IGF-I-mediated mechanisms in sex differences in cortical bone size in mice.

Cortical bone dimensions are important determinants of bone strength. Gender differences in cortical bone size caused by greater periosteal expansion in males than in females during the pubertal growth spurt are well established both in humans and in experimental animal models. However, the mechanism by which gender influences cortical bone size is still a matter of investigation. The role of androgens and estrogen in pubertal bone growth has been examined in human disorders as well as animal models, such as gonadectomized or sex steroid receptor knockout mice. Based on the findings that growth hormone (GH) and insulin-like growth factor I (IGF-I) are major regulators of postnatal skeletal growth, we and others have predicted that sex hormones interact with the GH/IGF-I axis to regulate cortical bone size. However, studies conflict as to whether estrogen and androgens impact cortical bone size through the canonical pathway, through GH without IGF-I mediation, through IGF-I without GH stimulation, or independent of GH/IGF-I. We review recent data on the impact of sex steroids and components of the GH/IGF axis on sexual dimorphism in bone size. While the GH/IGF-I axis is a major player in regulating peak bone size, the relative contribution of GH/IGF-dependent mechanisms to sex differences in cortical bone size remains to be established.

Differential effects of trisomy on brain shape and volume in related aneuploid mouse models.

Down syndrome (DS) results from inheritance of three copies of human chromosome 21 (Hsa21). Individuals with DS have a significantly smaller brain size overall and a disproportionately small cerebellum. The small cerebellum is seen in Ts65Dn mice, which have segmental trisomy for orthologs of about half the genes on Hsa21 and provide a genetic model for DS. While small cerebellar size is well-established in mouse and humans, much less is known about the shape of the brain in trisomy. Here we conduct a morphometric analysis of the whole brain and cerebellum in Ts65Dn mice and show that the differences with euploid littermates are largely a function of volume and not of shape. This is not the case in two aneuploid mouse models that have fewer genes orthologous to Hsa21 than Ts65Dn. Ts1Rhr is trisomic for genes corresponding to the so-called Down syndrome critical region (DSCR), which was purported to contain a dosage sensitive gene or genes responsible for many phenotypes of DS. Ms1Rhr is monosomic for the same segment. These models show effects on cerebellum and overall brain that are different from each other and from Ts65Dn. These models can help to identify the contributions of genes from different regions of the chromosome on this and other aspects of brain development in trisomy.

Trisomy for the Down syndrome 'critical region' is necessary but not sufficient for brain phenotypes of trisomic mice.

Trisomic Ts65Dn mice show direct parallels with many phenotypes of Down syndrome (DS), including effects on the structure of cerebellum and hippocampus. A small segment of Hsa21 known as the 'DS critical region' (DSCR) has been held to contain a gene or genes sufficient to cause impairment in learning and memory tasks involving the hippocampus. To test this hypothesis, we developed Ts1Rhr and Ms1Rhr mouse models that are, respectively, trisomic and monosomic for this region. Here, we show that trisomy for the DSCR alone is not sufficient to produce the structural and functional features of hippocampal impairment that are seen in the Ts65Dn mouse and DS. However, when the critical region is returned to normal dosage in trisomic Ms1Rhr/Ts65Dn mice, performance in the Morris water maze is identical to euploid, demonstrating that this region is necessary for the phenotype. Thus, although the prediction of the critical region hypothesis was disproved, novel gene dosage effects were identified, which help to define how trisomy for this segment of the chromosome contributes to phenotypes of DS.

Cardiac syndrome X and endothelial dysfunction: new concepts in prognosis and treatment.

Cardiac syndrome X (CSX), or angina with no flow-limiting stenosis on coronary angiogram, has been regarded as a condition with an excellent prognosis despite variable symptomatic improvement. Newer data show that patients with CSX with endothelial dysfunction have an increased risk for future adverse cardiac events. Current hypotheses of CSX pathophysiology emphasize a dysfunctional vascular endothelium that leads to microvascular ischemia. Treatments that target improving endothelial function, such as statins, angiotensin-converting enzyme inhibitors, estrogen, and lifestyle modification, are promising additions to treatment regimens for CSX. The goal of this article is to provide information for improved diagnosis, risk stratification, and therapy for the population with CSX.

Long-range chromosomal engineering is more efficient in vitro than in vivo.

Cre/LoxP mediated chromosomal engineering in embryonic stem (ES) cells has a variety of applications, including the creation of model systems for studying aneuploidy. Targeted meiotic recombination (TAMERE) was proposed as a high efficiency in vivo alternative to effect Cre-mediated recombination, in which Cre recombinase under control of the Synaptonemal Complex 1 promoter is expressed during male meiosis in transgenic mice. TAMERE has been successfully used with LoxP sites up to 100 kb apart. We tested TAMERE for a chromosome engineering application in which LoxP sequences were integrated into sites 3.9 Mb apart on the same (cis) or opposite (trans) copies of mouse Chromosome 16 (MMU16). TAMERE was ineffective in generating either a deletion or a translocation in vivo. The TAMERE method may be of limited use for large genomic rearrangements. The desired translocation was achieved with an in vitro method that can be used in any ES cell line. Mice produced from the reciprocal duplication/deletion of MMU16 in a region homologous to human chromosome 21 provide models that are useful in studies of Down syndrome.

Protection from doxorubicin-induced cardiac toxicity in mice with a null allele of carbonyl reductase 1.

Doxorubicin is a highly effective antineoplastic agent, but it can produce the serious side effects of acute cardiac injury and chronic congestive heart failure. Carbonyl reductase (CBR) has been implicated in the development of doxorubicin-induced cardiotoxicity. To test whether a decrease in CBR levels was protective against doxorubicin toxicity, we created a null allele of the Cbr1 gene. Mice with one functional copy of the gene (Cbr1 +/-) were healthy and grossly normal despite having decreased levels of Cbr1 transcript and protein. Control and Cbr1 +/- mice were administered doxorubicin at 20 mg/kg i.p. Cbr1 +/- mice showed decreased circulating levels of the cardiotoxic metabolite, doxorubicinol, after administration. Within 2 weeks, 91% of wild-type mice were severely affected (n = 11) compared with 18% of Cbr1 +/- mice (n = 11). Echocardiography and histological analysis showed that Cbr1 +/- mice were protected from gross and cellular level pathologies associated with doxorubicin treatment. Demonstration that inhibition of carbonyl reductase blocks the toxic effects on the heart has important implications for improving the use of doxorubicin in chemotherapy.