Limited ability to extend the digits of the human hand independently with extensor digitorum

While the human hand has an extraordinary capacity to manipulate objects, movement of its digits is usually not completely independent. These limits have been documented for extrinsic flexor muscles, although hand skills also require selectivity for extension movements. Hence, we measured the degree of independent control of the major extrinsic extensor (extensor digitorum, ED). Subjects grasped a cylinder, with the thumb perpendicular to the fingers. Load cells were connected to the proximal phalanges of the fingers and the thumb's distal phalanx. Intramuscular recordings using needle electrodes were made from the individual digital compartments of ED. Subjects were instructed to extend each digit isometrically in a voluntary ramp contraction to 50% maximal force. In total, the behaviour of 283 single motor units was analysed. More than half of the units associated with one 'test' finger were recruited inadvertently when another digit contracted to 50% maximum, with most units being recruited by extension of the adjacent digits. Usually, test motor units were recruited at higher forces by extension of fingers further from the test finger. Unexpectedly, extension of the thumb recruited many motor units acting on the little finger. Across tasks, at recruitment of the test motor units, the force produced by the test finger often differed between the voluntary and inadvertent contractions. Overall, the independent control of the output of ED is limited; this may reflect 'spill-over' of motor commands to other digital extensor compartments. This level of control of the extrinsic extensor muscles is more independent than the control of the deep extrinsic flexor muscle but less independent than that of the superficial extrinsic flexor muscle.     

Hereditary cerebral hemorrhage with amyloidosis‐Dutch type

The amyloid β‐protein (Aβ) E22Q mutation of the rare disorder hereditary cerebral hemorrhage with amyloidosis‐Dutch type (HCHWA‐D) causes severe cerebral amyloid angiopathy (CAA) with hemorrhagic strokes of mid‐life onset and dementia. The mutation does not affect total Aβ production but may alter the Aβ1–42:Aβ1–40 ratio, and affect the proteolytic degradation of Aβ and its transport across the blood–brain barrier. Aβ E22Q aggregates faster into more stable amyloid‐like fibrils than wild‐type Aβ. Non‐fibrillar Aβ(x‐42) deposits precede the appearance of fibrils and the deposition of Aβ(x‐40) in the vascular basement membrane. CAA severity tends to increase with age but may vary greatly among patients of comparable ages. Lumenal narrowing of affected blood vessels, leukoencephalopathy, CAA‐associated vasculopathies, and perivascular astrocytosis, microgliosis, and neuritic degeneration complicate the development of HCHWA‐D CAA. Parenchymal Aβ deposition is also enhanced in the HCHWA‐D brain with non‐fibrillar membrane‐bound Aβ(x‐42) deposits evolving into relatively fibrillar diffuse plaques variously associated with reactive astrocytes, activated microglia, and degenerating neurites. Plaque density tends to decrease with age. Neurofibrillary degeneration is absent or limited. HCHWA‐D dementia is associated with CAA severity independently of Braak stage, age, and plaque density. Particularly, microaneurysms may contribute to the development of (small) hemorrhages/infarcts and the latter to cognitive decline in affected subjects. However, the relative importance of cerebral hemorrhages/infarcts, white matter damage and/or other CAA‐ or Aβ‐related factors for cognitive deterioration in HCHWA‐D remains to be determined.     

High-field MRI of single histological slices using an inductively coupled, self-resonant microcoil: application to ex vivo samples of patients with Alzheimer's disease

A simple inductively coupled microcoil has been designed to image tissue samples placed on a microscope slide, samples which can subsequently be stained histologically. As the exact same tissue is used for MRI and histology, the two data sets can be compared without the need for complicated image registration techniques. The design can be integrated into any MRI system using existing commercial hardware. Compared with a commercial 25-mm-diameter birdcage, the signal-to-noise ratio was increased by a factor of 3.8, corresponding to an approximate 15-fold reduction in the data acquisition time. An example is shown of ex vivo samples from patients with Alzheimer's disease, in which the coregistration of highly sensitive iron staining and amyloid-β deposits is confirmed.     

New approach for handling glass ionomers in restorative dentistry

Potentially toxic products like the existing composites and their derivatives may harm both patients and dentists and therefore prudence is recommended, particularly in dentistry for children. Biocompatible glassionomers are a meaningful alternative for composites but have low strength and wear resistance. Mechanical properties of self curing GIC's can be improved by using heat-curing technique making them command set materials. This article is showing the clinical possibilities using this technique. The forming of the so-called pseudo enamel (Fluor-Apatite) is a unique property. Using this new methods lead to long lasting and biocompatible posterior GIC restorations which can mechanically in strength and wear but also in esthetics compete with posterior composites.     

Hypomelanotic macules in tuberous sclerosis

Summary Hypomelanotic macules of the skin in tuberous sclerosis (TS) are caused by a complex process, involving the synthesis and maturation of melanosomes. A quantitative method was developed to investigate the maturation of the melanosomes at the level of the melanocytes. The method was tested on biopsies of hypomelanotic and adjacent normomelanotic skin from six patients with definite TS, and compared with other methods.In all patients, a statistically significant lower number of pigmented melanosomes was found per cross-sectioned melanocytic perikaryon and dendritic cell process in the hypomelanotic as compared to the normomelanotic skin. The relative numbers of stage III and IV melanosomes were decreased, and of stage II melanosomes increased in the hypomelanotic macule (also statistically significant). This indicates that it is possible to characterize the hypomelanosis in TS reliably, which may have diagnostic importance. In our hands, assessment of the size of the melanosomes did not show a statistically significant difference between hypo- and normomelanotic skin; the difference found with the DOPA technique was more evident, although not statistically significant.