Temporal course of cognitive and behavioural changes in motor neuron diseases

BACKGROUND

Cognitive and behavioural dysfunction may occur in people with motor neuron disease (MND), with some studies suggesting an association with the C9ORF72 repeat expansion. Their onset and progression, however, is poorly understood. We explored how cognition and behaviour change over time, and whether demographic, clinical and genetic factors impact these changes.

METHODS

Participants with MND were recruited through the Phenotype-Genotype-Biomarker study. Every 3-6 months, the Edinburgh Cognitive and Behavioural ALS Screen (ECAS) was used to assess amyotrophic lateral sclerosis (ALS) specific (executive functioning, verbal fluency, language) and ALS non-specific (memory, visuospatial) functions. Informants reported on behaviour symptoms via semi-structured interview.

RESULTS

Participants with neuropsychological data at ≥3 visits were included (n=237, mean age=59, 60% male), of which 18 (8%) were C9ORF72 positive. Baseline cognitive impairment was apparent in 18 (8%), typically in ALS specific domains, and associated with lower education, but not C9ORF72 status. Cognition, on average, remained stable over time, with two exceptions: (1) C9ORF72 carriers declined in all ECAS domains, (2) 8%-9% of participants with baseline cognitive impairment further declined, primarily in the ALS non-specific domain, which was associated with less education. Behavioural symptoms were uncommon.

CONCLUSIONS

In this study, cognitive dysfunction was less common than previously reported and remained stable over time for most. However, cognition declines longitudinally in a small subset, which is not entirely related to C9ORF72 status. Our findings raise questions about the timing of cognitive impairment in MND, and whether it arises during early clinically manifest disease or even prior to motor manifestations.

Age- and fitness-related differences in limb venous compliance do not affect tolerance to maximal lower body negative pressure in men and women

Aging and chronic exercise training influence leg venous compliance. Venous compliance affects responses to an orthostatic stress; its effect on tolerance to maximal lower body negative pressure (LBNP) in the elderly is unknown. The purpose of this study was to determine the influence of age and fitness, a surrogate measure of exercise training, on calf venous compliance and tolerance to maximal LBNP in men and women. Forty participants, 10 young fit (YF; age = 22.6 ± 0.5 yr, peak oxygen uptake = 57.1 ± 2.0 ml·kg−1·min−1), 10 young unfit (YU; 23.1 ± 1.0 yr, 41.1 ± 2.0 ml·kg−1·min−1), 10 older fit (OF; 73.9 ± 2.0 yr, 39.0 ± 2.0 ml·kg−1·min−1), and 10 older unfit (OU; 70.9 ± 1.6 yr, 27.1 ± 2.0 ml·kg−1·min−1), underwent graded LBNP to presyncope or 4 min at −100 mmHg. By utilizing venous occlusion plethysmography, calf venous compliance was determined by using the first derivative of the pressure-volume relation during cuff pressure reduction. We found that the more fit groups had greater venous compliance than their unfit peers ( P < 0.05) as did the young groups compared with their older peers ( P < 0.05) such that OU < YU = OF < YF. LBNP tolerance did not differ between groups. In conclusion, these data suggest that aging reduces, and chronic exercise increases, venous compliance. However, these data do not support a significant influence of venous compliance on LBNP tolerance.

Cor triatriatum dexter: transesophageal echocardiographic diagnosis and 3-dimensional reconstruction

Cor triatriatum dexter is an unusual cardiac abnormality with division between the sinus and primitive atrial portions of the right atrium. Three-dimensional echocardiography is a novel technique that defines this entity.

Changes in the metabolism of the microalga Chlorella vulgaris when coimmobilized in alginate with the nitrogen-fixing Phyllobacterium myrsinacearum

In an agroindustrial wastewater pond, a naturally occurring unicellular microalga, Chlorella vulgaris, was closely associated with the terrestrial plant-associative N2-fixing bacterium Phyllobacterium myrsinacearum. When the two microorganisms were artificially coimmobilized in alginate beads, they shared the same internal bead cavities, and the production of five microalgal pigments increased, but there were no effects on the number of the cells or the biomass of the microalga. The association, however, reduces the ability of C. vulgaris to remove ammonium ions and phosphorus from water. The bacterium produced nitrate from ammonium in synthetic wastewater with or without the presence of the microalga, and fixed nitrogen in two culture media. Our results suggest that interactions between microalgae and associative bacteria should be considered when cultivating microalgae for wastewater treatment.

Lattice-gas model driven by Hubbard electrons

Self-consistent Monte Carlo simulations are undertaken for a lattice-gas model which is driven by the free energy of electrons described by a Hubbard model with electronic hopping restricted to ions at nearest-neighbor sites. Our previous work, an independent-electron tight-binding lattice-gas model (bcc or fcc), is modified to introduce two effects: the disorder of the dense system and, more importantly, the role of the electronic correlation. The first effect is achieved using an fcc lattice, but restricted so an occupied site can have no more than eight, instead of twelve, occupied nearest-neighbor sites. To treat correlations, the electronic intra-atomic repulsion is, at first, included via the Gutzwiller approximation at finite temperature; this approach is simple enough to be solved for all cases in the large, disordered systems used in our Monte Carlo simulations but can still give a good qualitative representation of the main effects of the electronic correlations. Then, the exact treatment of the Hubbard model for clusters with up to six atoms is integrated into the calculation. We obtain vapor-liquid coexistence curves and then, approximations to the electronic conductivities and paramagnetic susceptibilities at coexistence conditions. This simple model is, in part, motivated by experiments on the alkali-metal fluids.

Safety and efficacy of 4-aminopyridine in humans with spinal cord injury: a long-term, controlled trial

STUDY OBJECTIVE

To determine the effects of the long-term administration of 4-aminopyridine (4-AP) on sensorimotor function in humans with long-standing spinal cord injury (SCI).

DESIGN

Randomized, open-label, active-treatment control, dosage-blinded study.

SETTING

University-affiliated, tertiary-level care, Department of Veterans Affairs Medical Center.

PATIENTS

Twenty-one healthy men and women outpatients suffering from traumatic SCI (14 tetraplegic, 7 paraplegic) for 2 years or more.

INTERVENTIONS

Dosages of an immediate-release formulation of 4-AP were titrated. At 3 months, 16 subjects were receiving 4-AP 30 mg/day (high dose); 5 subjects were receiving 4-AP 6 mg/day (low dose) and served as an active-treatment control group.

MEASUREMENTS AND MAIN RESULTS

Composite motor and sensory scores had statistically significant increases at 3 months. Maximal expiratory pressure, maximal inspiratory pressure, forced vital capacity, and forced expiratory volume in 1 second showed clinically meaningful and/or statistically significant increases among patients receiving 4-AP 30 mg/day. These subjects also had significant decreases in spasticity (modified Ashworth Scale). Serial biochemical profiles and electroencephalographs were unchanged from baseline, and no clinically significant drug toxicity was encountered.

CONCLUSIONS

Long-term oral administration of immediate-release 4-AP was associated with improvement in and recovery of sensory and motor function, enhanced pulmonary function, and diminished spasticity in patients with long-standing SCI. 4-Aminopyridine appears to be safe and relatively free from toxicity when administered orally over 3 months. Each patient who received immediate-release 4-AP 30 mg/day showed a response in one or more of the outcome measures.

Inhibition of human telomerase by a retrovirus expressing telomeric antisense RNA

Human telomerase, the RNA-dependent DNA polymerase that adds TTAGGG repeats to chromosome ends, is selectively expressed in immortalised cells and most tumours, suggesting a potential role for telomerase inhibitors in cancer therapy. Replication-deficient retroviruses were used to determine whether mRNA containing UUAGGG, the complementary sequence to the template region of the hTR telomerase RNA, is sufficient to inhibit telomerase activity. Telomerase activities measured by the telomeric repeat amplification protocol (TRAP) assay in extracts prepared from immortalised mouse fibroblasts, human HeLa cells and human kidney carcinoma cells were inhibited by 75% or greater in 26 of 56 cell clones expressing UUAGGG. Telomerase activity was not inhibited by expression of mRNA containing a transposed sequence, GGGAUU. Telomerase activities in vivo were inferred from changes in cellular morphology, proliferation capacity, growth rate and measurement of the content of telomere DNA. Giant senescent-like cells emerged shortly after cloning mouse PA317 and human HeLa cells expressing UUAGGG. The fraction of giant cells varied from 100% at the fifth population doubling (PD) in one culture to 2-6% at 50 PD in several other cultures. Giant cells were absent in all parental cells and clones expressing GGGAUU. The average cellular content of telomere DNA was independent of telomerase activity over 50 PD. The results indicate that expression of RNA complementary to the template region of hTR is sufficient to inhibit telomerase in vitro and in vivo, but that the effect of inhibition on individual cells is highly variable.

[Two-dimensional echography with a real-time scanner in extrauterine pregnancy (author's transl)]

Fifty-nine cases of ectopic pregnancies in the region of the adnexa and 2 cases with intracervical localization were described with the help of picutres acquired via the so-called "rapid intensity modulated ultrasonography". The findings were based on 16,000 examinations. Problems involved with interpretations were presented. The possiblities and limitations of the methods were discussed in light of the available literature.