Johan Holmberg

The local surface density of disc matter mapped by Hipparcos

We determine the surface density of matter in the disc of the Galaxy at the solar position using K giant stars. The local space density and luminosity function of the giants is determined using parallaxes from the Hipparcos satellite; for more distant giants, observed in a cone at the South Galactic Pole, distances are determined using intermediate-band DDO photometry (which has been calibrated to the Hipparcos absolute magnitudes). From this sample, we determine the gravitational potential vertically of the local Galactic disc, by comparing the number of giant stars observed in the cone with the number expected for various models of the matter distribution in the disc. We derive an estimate of the dynamical disc mass surface density of 56 ± 6 M ○. pc -2 , which may be compared to an estimate of 53 M ○. pc -2 in visible matter. For all gravitating matter (disc + dark halo) we find the total density within 1.1 kpc of the disc midplane to be 74 ± 6 M ○. pc -2 . As has been found by a number of studies, including our own, we find no compelling evidence for significant amounts of dark matter in the disc.

The solar neighbourhood age-metallicity relation - Does it exist?

We test the hypothesis that the spread in the age-metallicity plot of the solar neighborhood is due to a mixture of stars belonging to kinematically different sub-populations of the Galactic disk, i.e., the thin and the thick disk. We use a kinematic subsample of similar to 600 stars from a sample of similar to 6000 dwarf and subgiant stars from the Hipparcos catalog. All of these stars have a full set of stellar parameters determined, including good ages. We find that a significant spread in [Me/H] is present in both kinematic populations, especially at large stellar ages. This implies that a simple one-to-one relation between ages and metallicities is not possible. In fact, there are stars that are-truly old and at the same time have [Me/H] > 0.2 dex. (Less)

Treatment of phobic postural vertigo. A controlled study of cognitive-behavioral therapy and self-controlled desensitization.

In balance clinic practice, phobic postural vertigo is a term used to define a population with dizziness and avoidance behavior often as a consequence of a vestibular disorder. It has been described as the most common form of dizziness in middle aged patients in dizziness units. Anxiety disorders are common among patients with vestibular disorders. Cognitive–behavioral therapy is an effective treatment for anxiety disorders, and vestibular rehabilitation exercises are effective for vestibular disorders. This study compared the effect of additional cognitive–behavioral therapy for a population with phobic postural vertigo with the effect of self–administered vestibular rehabilitation exercises.39 patients were recruited from a population referred for otoneurological investigation. Treatment effects were evaluated with the Dizziness Handicap Inventory, Vertigo Symptom Scale, Vertigo Handicap Questionnaire, and Hospital Anxiety and Depression Scale. All patients had a self treatment intervention based on education about the condition and recommendation of self exposure by vestibular rehabilitation exercises. Every second patient included was offered additional cognitive behavioral therapy.Fifteen patients with self treatment and 16 patients with cognitive– behavioral treatment completed the study. There was significantly larger effect in the group who received cognitive behavioral therapy than in the self treatment group in Vertigo Handicap Questionnaire and the Hospital Anxiety and Depression scale and its subscales.Cognitive–behavioral therapy has an additional effect as treatment for a population with phobic postural vertigo.A multidisciplinary approach including medical treatment, cognitive–behavioral therapy and physiotherapy is suggested.

A Study of the Functionalities of the Phases in Mo–V–Nb–Te Oxides for Propane Ammoxidation

Catalysts belonging to the Mo–V–Nb–Te–O system have been prepared with both a slurry method and hydrothermal synthesis and were tested for propane and propylene ammoxidation to acrylonitrile. All samples were characterized with BET, XRD, ICP and XPS. The catalysts were found to consist of three phases, to which activity and selectivity correlations were made. The results indicate that both an orthorhombic phase and a hexagonal phase are needed to have an active and selective catalyst. The orthorhombic phase is the most active for propane conversion although less selective than the hexagonal phase for the conversion of formed propylene to acrylonitrile.

One-year follow-up of cognitive behavioral therapy for phobic postural vertigo

BackgroundPhobic postural vertigo is characterized by dizziness in standing and walking despite normal clinical balance tests. Patients sometimes exhibit anxiety reactions and avoidance behavior to specific stimuli. Different treatments are possible for PPV, including vestibular rehabilitation exercises, pharmacological treatment, and cognitive behavioral therapy. We recently reported significant benefits of cognitive behavioural therapy for patients with phobic postural vertigo. This study presents the results of a one-year follow-up of these patients.MethodsSwedish translations of the following questionnaires were administered: (Dizziness Handicap Inventory, Vertigo Symptom Scale, Vertigo Handicap Questionnaire, and Hospital Anxiety and Depression Scale) were administered to 20 patients (9 men and 11 women; mean age 43 years, range 23–59 years) one year after completion of cognitive behavioral therapy.ResultsTest results were similar to those obtained before treatment, showing that no significant treatment effects remained.ConclusionCognitive behavioral therapy has a limited long-term effect on phobic postural vertigo. This condition is more difficult to treat than panic disorder with agoraphobia. Vestibular rehabilitation exercises and pharmacological treatment might be the necessary components of treatment.

Laminin-211 in skeletal muscle function

A chain is no stronger than its weakest link is an old idiom that holds true for muscle biology. As the name implies, skeletal muscle’s main function is to move the bones. However, for a muscle to transmit force and withstand the stress that contractions give rise to, it relies on a chain of proteins attaching the cytoskeleton of the muscle fiber to the surrounding extracellular matrix. The importance of this attachment is illustrated by a large number of muscular dystrophies caused by interruption of the cytoskeletal-extracellular matrix interaction. One of the major components of the extracellular matrix is laminin, a heterotrimeric glycoprotein and a major constituent of the basement membrane. It has become increasingly apparent that laminins are involved in a multitude of biological functions, including cell adhesion, differentiation, proliferation, migration and survival. This review will focus on the importance of laminin-211 for normal skeletal muscle function.

Cib2 binds integrin a7Bb1D and is reduced in laminin a2 chain deficient muscular dystrophy

Mutations in the gene encoding laminin α2 chain cause congenital muscular dystrophy type 1A. In skeletal muscle, laminin α2 chain binds at least two receptor complexes: the dystrophin-glycoprotein complex and integrin α7β1. To gain insight into the molecular mechanisms underlying this disorder, we performed gene expression profiling of laminin α2 chain-deficient mouse limb muscle. One of the down-regulated genes encodes a protein called Cib2 (calcium- and integrin-binding protein 2) whose expression and function is unknown. However, the closely related Cib1 has been reported to bind integrin αIIb and may be involved in outside-in-signaling in platelets. Since Cib2 might be a novel integrin α7β1-binding protein in muscle, we have studied Cib2 expression in the developing and adult mouse. Cib2 mRNA is mainly expressed in the developing central nervous system and in developing and adult skeletal muscle. In skeletal muscle, Cib2 colocalizes with the integrin α7B subunit at the sarcolemma and at the neuromuscular and myotendinous junctions. Finally, we demonstrate that Cib2 is a calcium-binding protein that interacts with integrin α7Bβ1D. Thus, our data suggest a role for Cib2 as a cytoplasmic effector of integrin α7Bβ1D signaling in skeletal muscle.

Phobic postural vertigo: body sway during vibratory proprioceptive stimulation

&NA; Phobic postural vertigo patients might rely more on proprioceptive than visual cues to regulate stance. We tested 14 phobic postural vertigo patients and 24 healthy subjects with posturography during quiet stance and periods of vibratory proprioceptive calf muscle stimulation, both with eyes open and closed. During quiet stance phobic postural vertigo patients showed higher torque variance than healthy subjects, especially above 0.1 Hz.Vibratory proprioceptive stimulation increased the differences between healthy subjects and phobic postural vertigo patients. The patients were less able to use vision to counteract vibration‐induced movements. Phobic postural vertigo patients are more sensitive to proprioceptive disturbances than healthy subjects are, and less apt to use visual information to control upright stance. This might be part of an anxious mode of balance control.

Experience of handicap and anxiety in phobic postural vertigo

Conclusions We found a difference in gender distribution in a population of phobic postural vertigo patients compared with dizzy patients seen in general neuro-otological practice. It appears as if women with phobic postural vertigo suffer more and are more handicapped by dizziness than both men with phobic postural vertigo and a population with dizziness. These differences may reflect other causes of phobic postural vertigo besides anxiety, such as gender-related coping behaviour and postural strategy. Objective Anxiety influences the degree of suffering and handicap in dizzy patients. Experiences of anxiety and handicap were investigated among a population with phobic postural vertigo. Material and methods Using the Dizziness Handicap Inventory, the Vertigo Symptom Scale and the Vertigo Handicap Questionnaire, 34 consecutive patients with phobic postural vertigo were compared with a population of 95 consecutive patients seen at a balance disorder clinic. Results Patients with phobic postural vertigo scored higher than the control subjects with respect to all parameters with the exception of the physical subscale of the Dizziness Handicap Inventory. Because there were significantly more women in the control group we performed a gender-specific analysis of the results. The higher test scores among patients with phobic postural vertigo can be explained by the higher scores among women in this group, while the test results for men were more similar to those of the control group.

Laminin α2 Chain-Deficiency is Associated with microRNA Deregulation in Skeletal Muscle and Plasma.

microRNAs (miRNAs) are widespread regulators of gene expression, but little is known of their potential roles in congenital muscular dystrophy type 1A (MDC1A). MDC1A is a severe form of muscular dystrophy caused by mutations in the gene encoding laminin α2 chain. To gain insight into the pathophysiological roles of miRNAs associated with MDC1A pathology, laminin α2 chain-deficient mice were evaluated by quantitative PCR. We demonstrate that expression of muscle-specific miR-1, miR-133a, and miR-206 is deregulated in laminin α2 chain-deficient muscle. Furthermore, expression of miR-223 and miR-21, associated with immune cell infiltration and fibrosis, respectively, is altered. Finally, we show that plasma levels of muscle-specific miRNAs are markedly elevated in laminin α2 chain-deficient mice and partially normalized in response to proteasome inhibition therapy. Altogether, our data suggest important roles for miRNAs in MDC1A pathology and we propose plasma levels of muscle-specific miRNAs as promising biomarkers for the progression of MDC1A.