Effects of hypoxia and hypercapnic hypoxia on the ultrastructure of central nervous synapses

Exploring links between 2-oxoglutarate-dependent oxygenases and Alzheimer's disease

Hypoxia, that is, an inadequate oxygen supply, is linked to neurodegeneration and patients with cardiovascular disease are prone to Alzheimer's disease (AD). 2-Oxoglutarate and ferrous iron-dependent oxygenases (2OGDD) play a key role in the regulation of oxygen homeostasis by acting as hypoxia sensors. 2OGDD also have roles in collagen biosynthesis, lipid metabolism, nucleic acid repair, and the regulation of transcription and translation. Many biological processes in which the >60 human 2OGDD are involved are altered in AD patient brains, raising the question as to whether 2OGDD are involved in the transition from normal aging to AD. Here we give an overview of human 2OGDD and critically discuss their potential roles in AD, highlighting possible relationships with synapse dysfunction/loss. 2OGDD may regulate neuronal/glial differentiation through enzyme activity-dependent mechanisms and modulation of their activity has potential to protect against synapse loss. Work linking 2OGDD and AD is at an early stage, especially from a therapeutic perspective; we suggest integrated pathology and in vitro discovery research to explore their roles in AD is merited. We hope to help enable long-term research on the roles of 2OGDD and, more generally, oxygen/hypoxia in AD. We also suggest shorter term empirically guided clinical studies concerning the exploration of 2OGDD/oxygen modulators to help maintain synaptic viability are of interest for AD treatment.

Diffusion MRI in three types of anoxic encephalopathy

We report the clinical and diffusion-weighted MRI (DWI) features of three patients with different types of anoxic brain injury: attempted hanging (hypoxic hypoxia), carbon monoxide poisoning (histotoxic hypoxia), and hanging with cardiac arrest (hypoxic-ischemic encephalopathy, HIE). The first two patients, but not the third, recovered substantial neurological function. The distribution of DWI abnormalities was different and correlated well with the distinct neuropathological features of these entities. The prognosis after anoxic encephalopathy depends on the underlying mechanism and its severity, which may be reflected by DWI abnormalities.

Altered axon terminals containing concentric lamellar bodies of cerebellar Purkinje cells in Mongolian gerbil

Altered axon terminals containing concentric lamellar bodies were observed in cerebellar and vestibular nuclei of the Mongolian gerbil. The terminals increased in number from 30 days of age onward, and reached about tenfold at 360 days. The numbers were the same in two gerbil strains with different susceptibility to spontaneous motor seizures by various stimuli, but about threefold those in Slc:Wistar rat.

Membranous cytoplasmic bodies in the lateral wall of the cat cochlea

Membranous cytoplasmic bodies (MCBs) were observed both in the intermediate cells of the stria vascularis and in the fibrocytes of the spiral ligament in normal cats. The MCBs in the intermediate cells were round or ovoid, ranged from 1 to 5 microns in diameter, and consisted of 2 to 40 or more layers disposed concentrically about a core. The core was composed of not only cytoplasm but also of mitochondria in various stages of disintegration, empty vacuoles, and many kinds of dense bodies similar to lysosomes. The MCBs in the fibrocytes were similar to those in the intermediate cells, but they were a little smaller in diameter and consisted of fewer than 10 layers. Both in the intermediate cells and in the fibrocytes, MCBs seem to have a phagocytic function.

A methodological approach to rapid and sensitive monoamine histofluorescence using a modified glyoxylic acid technique: the SPG method

A modified approach of the glyoxylic acid (GA) condensation reaction for the visualization of biogenic amines in tissue is described. Cryostat sections are used from brain or extracerebral tissue in dog, monkey, rat and mouse and exposed for 3 s to a room temperature solution containing sucrose-potassium phosphate-glyoxylic acid (SPG). The tissues are air dried and heated in an oven for 5 min. The complete precessing time from fresh tissue to microscopic examineation takes 18 min. Morphologically sharp and brightly fluorescent monoamine-containing neurons, pre- and terminal axons are seen against a dark parenchymal background without drug pre-treatment. The SPG method retains the high specific sensitivity for monoamines previously described in the original technique but is, in addition, more rapid and simple and is easily accissible as a research tool to investigators inexperienced in histofluoresecence techniques.

The effect of "ouabain" on the ultrastructure of cerebral arterioles and surrounding tissue, studied by a cannulation of a cerebral artery

A technique for cannulation of a parietal branch of the middle cerebral artery is described by which high but local concentrations of substances can be achieved in cortical vessels. Using this technique it was shown that ouabain, a specific inhibitor of the Na+-K+-ATPase enzyme system, can produce alterations in the blood brain barrier (BBB) permeability as seen by the passage of Evans Blue into cortical tissue. Electron microscopy revealed changes in the endothelium of cerebral arterioles ranging from an increase in the number of vesicles and vacuoles to complete breakdown of cytoplasm and membranes. Swelling of the peri-arteriolar end feet of protoplasmic astroglia and of dendrites was characteristic of tissue surrounding affected arterioles. Swollen fibrous astrocytes, oligodendrocytes and microglia were not seen even in areas of vasogenic edema. These results are discussed in terms of current ideas of the BBB and astroglial function.