Photometric determination of glycogen in stained liver sections

Summary Sections of developing chicken liver stained for glycogen according to Best have been photometrically analysed. It is concluded that such photometric determinations may be performed with a high degree of reliability and reproducibility.There is a close direct proportionality between the optical density in Best-stained sections and the chemically determined concentration of bound glycogen.This study was supported in part by a grant from the Swedish Medical Research Council.     

The intranuclear movement of Balbiani ring premessenger ribonucleoprotein particles.

Specific premessenger ribonucleoprotein (pre-mRNP) particles, the Balbiani ring (BR) granules in the salivary glands of the dipteran Chironomus tentans, can be visualized in the electron microscope when they assemble on the genes, move through nucleoplasm, and bind to and translocate through the nuclear pores. As shown by BrUTP labeling and immunoelectron microscopy, newly synthesized BR RNP particles, released from the BR genes, appear early in all nucleoplasmic regions of the cell nucleus and they saturate the nucleoplasmic pool of BR particles after 2 h of labelling. It is concluded that within the nucleus the BR particles move randomly. Furthermore, estimates of minimum diffusion coefficients for the BR particles are compatible with the view that the particles diffuse freely in the interchromosomal space, although it is not excluded that the random movement could be slightly retarded. Once the particles get bound to the nuclear pore complexes, they seem committed to translocation through the nuclear pores.     

Modulation of adenylate cyclase activity by sulfated glycosaminoglycans II. Effects of mucopolysaccharides and dextran sulfate on the activity of adenylate cyclase derived from various tissues

Heparin was found to be the most potent inhibitor of rat ovarian luteinizing hormone-sensitive adenylate cyclase (I₅₀ = 2 μg/ml) when compared to other naturally occurring glycosaminoglycans. This inhinibition was also appparent when this enzyme was stimulated by follicle-stimulating hormone or prostaglandin E ₂. Heparin was also found to inhibit glucagon-sensitive rat hepatice adenylate cyclase, and the prostaglandin E₁-sensitive enzyme from rat ileum and human platelets. In contrast, heparin stimulated the dopamine sensitive adenylate cyclase from rat caudate nucleus. The sulfade polysugar dextran sulfate exerts similar effects on adenylate cyclase activity of the rat ovary was shown to inhibit hormone binding to rat ovarian plasma membrane in a manner similar to that exerted by heparin. In contrast to heparin, dextran sulfate inhibited dopamine-sensitive adenylate cyclase from rat caudate nucleus.     

Demonstration of endocytosis vesicles by means of electron-microscopic histochemistry

Summary A phosphatase activity similar to that of the plasma membrane is demonstrated at the inside of the membrane, which delimits the lipid-containing lysosomes of chicken liver parenchymal cells. This is taken as a definite confirmation of their endocytotic origin.It should be possible to demonstrate endocytosis vesicles in other cells in this way. It is, however, pointed out, that cells with a weak plasma membrane activity may require particular attention to certain steps in the technical procedure.This study was supported in part by a grant from the Swedish Medical Research Council.     

Structural determinants of multimerization and dissociation in 2-Cys peroxiredoxin chaperone function

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Über den chemischen Aufbau der Strukturen des Zellkernes

Ohne ZusammenfassungReferat über die gleichnamige Arbeit in: Skandinav. Arch. für Physiologie, Band 73, Suppl. Nr. 8, 1936.     

No Diagnostic Value of Plasma Clusterin in Alzheimer's Disease

There is an urgent need for biomarkers to enable early diagnosis of Alzheimer''s disease (AD). It has recently been shown that a variant within the clusterin gene is associated with increased risk of AD and plasma levels of clusterin have been found to be associated with the risk of AD. We, therefore, investigated the diagnostic value of clusterin by quantifying clusterin using an ELISA in plasma from 171 controls, 127 patients with AD, 82 patients with other dementias and 30 patients with depression. We observed similar plasma clusterin levels in controls, AD patients and patients with other dementias, suggesting that plasma clusterin levels have no diagnostic value for AD. There was a slight, but significant, increase in plasma clusterin in patients with depression compared to all other groups tested, which may warrant further investigation.     

Glutamate dehydrogenase deficiency disrupts glutamate homeostasis in hippocampus and prefrontal cortex and impairs recognition memory

Glutamate Dehydrogenase 1 (GDH), encoded by the Glud1 gene in rodents, is a mitochondrial enzyme critical for maintaining glutamate homeostasis at the tripartite synapse. Our previous studies indicate that the hippocampus may be particularly vulnerable to GDH deficiency in central nervous system (CNS). Here, we first asked whether mice with a homozygous deletion of Glud1 in CNS (CNS‐Glud1 ?/? mice) express different levels of glutamate in hippocampus, and found elevated glutamate as well as glutamine in dorsal and ventral hippocampus, and increased glutamine in medial prefrontal cortex (mPFC). l ‐serine and d ‐serine, which contribute to glutamate homeostasis and NMDA receptor function, are increased in ventral but not dorsal hippocampus, and in mPFC. Protein expression levels of the GABA synthesis enzyme glutamate decarboxylase (GAD) GAD67 were decreased in the ventral hippocampus as well. Behavioral analysis revealed deficits in visual, spatial and social novelty recognition abilities, which require intact hippocampal‐prefrontal cortex circuitry. Finally, hippocampus‐dependent contextual fear retrieval was deficient in CNS‐Glud1 ?/? mice, and c‐Fos expression (indicative of neuronal activation) in the CA1 pyramidal layer was reduced immediately following this task. These data point to hippocampal subregion‐dependent disruption in glutamate homeostasis and excitatory/inhibitory balance, and to behavioral deficits that support a decline in hippocampal‐prefrontal cortex connectivity. Together with our previous data, these findings also point to different patterns of basal and activity‐induced hippocampal abnormalities in these mice. In sum, GDH contributes to healthy hippocampal and PFC function; disturbed GDH function is relevant to several psychiatric and neurological disorders.