Increased Expression of Apolipoprotein D Following Experimental Traumatic Brain Injury

Increasing evidence suggests that apolipoprotein D (apoD) could play a major role in mediating neuronal degeneration and regeneration in the CNS and the PNS. To investigate further the temporal pattern of apoD expression after experimental traumatic brain injury in the rat, male Sprague-Dawley rats were subjected to unilateral cortical impact injury. The animals were killed and examined for apoD mRNA and protein expression and for immunohistological analysis at intervals from 15 min to 14 days after injury. Increased apoD mRNA and protein levels were seen in the cortex and hippocampus ipsilateral to the injury site from 48 h to 14 days after the trauma. Immunohistological investigation demonstrated a differential pattern of apoD expression in the cortex and hippocampus, respectively: Increased apoD immunoreactivity in glial cells was detected from 2 to 3 days after the injury in cortex and hippocampus. In contrast, increased expression of apoD was seen in cortical and hippocampal neurons at later time points following impact injury. Concurrent histopathological examination using hematoxylin and eosin demonstrated dark, shrunken neurons in the cortex ipsilateral to the injury site. In contrast, no evidence of cell death was observed in the hippocampus ipsilateral to the injury site up to 14 days after the trauma. No evidence of increased apoD mRNA or protein expression or neuronal pathology by hematoxylin and eosin staining was detected in the contralateral cortex and hippocampus. Our results reveal induction of apoD expression in the cortex and hippocampus following traumatic brain injury in the rat. Our data also suggest that increased apoD expression may play an important role in cortical neuronal degeneration after brain injury in vivo. However, increased expression of apoD in the hippocampus may not necessarily be indicative of neuronal death.     

Atrial natriuretic peptide detected by immunocytochemistry in peripheral organs of Tupaia belangeri

ANP (atrial natriuretic peptide), a peptide found in granules of mammalian atrial cardiac myocytes, has been shown to be active in regulation of blood pressure and body water homeostasis. The existence of ANP in atrium, pituitary, adrenal gland, and kidney of the rat had been immunocytochemically demonstrated with an antibody against rat ANP (102-126). We used the same antibody in immunocytochemical studies for the detection of ANP in peripheral organs of the tree shrew (Tupaia belangeri). The antibody stained granules in myocytes of cardiac atria which indicated that it reacted with tree shrew ANP. In contrast to the rat, no immunoreactive cells were found in pituitaries and adrenal glands. However, in the kidneys distal tubules in outer medulla and cortex were labeled. Ascending limbs of distal tubules were intensely stained when either the peroxidase-antiperoxidase (PAP) or the indirect immunofluorescence method were used. Collecting ducts and convoluted distal tubules in the outer cortex showed a granular type of staining when the immunofluorescence method was used. These data indicate that ANP is present in epithelial cells of distal tubules and collecting ducts, where it may be involved in the regulation of renal salt excretion.     

Purification and characterization of a gelatinase produced by fibroblasts from human gingiva

An endopeptidase which digests denatured collagen to small, dialysable fragments was purified 2675-fold from medium that had been conditioned by the culture of fibroblasts grown from explants of human gingiva. This enzyme was inhibited by chelating agents, but not by phenylmethylsulphonyl fluoride nor by N-ethylmaleimide, and is therefore probably a metalloproteinase. It showed no demonstrable activity against native collagen or ovalbumin, while alpha-casein was digested slowly, if at all. It therefore belongs to the group of enzymes which have been called tissue gelatinases. This gelatinase was secreted in a latent form or forms and could be activated by proteolysis with trypsin. The active enzyme had an apparent molecular weight of 69 000 (gel chromatography) or 72 000 (gel electrophoresis in sodium dodecyl sulphate) and an apparent isoelectric point of 4.15.     

Effect of dolichyl monophosphate on the permeability properties of lipid membranes

The effect of dolichyl monophosphate on the permeability properties of dimyristoylphosphatidylcholine bilayers to alkaline cations, Ca²⁺ and glucose has been determined by stop-flow spectrophotometry. The results show that, in con trast to free dolichol effects, the monophosphate derivative increased the permeability following a decreasing order of the permeating particle size. Phase diagrams indicate that dolichyl monophosphate is fully incorporated into the phosphatidylcholine bilayer around 0.75% weight/weight ratio. For these ratios, the permeation of ions is higher in the gel than in the liquid crystalline state.     

Receptive fields of neurons of cat suprasylvian gyrus studied by stimuli of different colors

Receptive fields of 83 neurons in the Clare-Bishop area and 75 neurons in cortical areas 17 and 18 were studied. Testing receptive fields of neurons in the Clare-Bishop area by stimuli of different colors revealed differences in their structure, in 95% of neurons, depending on stimulus color. The structure of the receptive fields of neurons in areas 17 and 18 remained unchanged under these conditions. It is suggested that the Clare-Bishop area participates in color vision in the cat.I. S. Beritashvili Institute of Physiology, Academy of Sciences of the Georgian SSR, Tbilisi. Translated from Neirofiziologiya, Vol. 14, No. 6, pp. 644–650, November–December, 1982.