Effect of DN-1417, a thyrotropin releasing hormone analog, on dopaminergic neurons in rat brain

Acute and chronic effects of γ-butyrolactone-γ-carbonyl-histidyl-prolinamide (DN-1417) were investigated on motor activity, dopamine (DA) metabolites and DA receptors in various brain regions of rats. The motor activity, as measured with Automex recorder, was enhanced after a single injection with DN-1417 (20 mg/kg, IP), and the motor stimulating action persisted during 21 daily injections. Acute DN-1417 elevated both homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC) levels in 7 brain regions, prefrontal cortex polar, medial and lateral fields, nucleus accumbens, olfactory tubercles, amygdala and striatum. After chronic treatment for 7 days, the acute effect of DN-1417 on DA metabolites disappeared in all regions except for the striatum in which DN-1417 still increased HVA and DOPAC. The response of striatal DA metabolites was also observed after chronic treatment for 21 days. Chronic DN-1417 produced no significant change in ³H-spiperone binding in the prefrontal cortex, nucleus accumbens, olfactory tubercles and striatum, while striatal ³H-DA binding displaced by 30 nM spiperone was enhanced after chronic treatment. These results indicate that DN-1417 interacts with mesocortical, mesolimbic and nigrostriatal DA systems in the different modes of action. The lack of tolerance to motor hyperactivity, however, raises the question as to whether DN-1417-induced hyperactivity may be mediated by the activation of mesolimbic DA neurons. The involvement of nigrostriatal neurons in DN-1417-induced motor hyperactivity is suggested.     

Purification and characterization of an antibacterial factor from snail mucus

The antibacterial factor from the body surface of the African giant snail, Achatina fulica Férussac, was isolated by DEAE-Toyopearl 650M ion exchange chromatography. The isolated preparation exhibited highly positive antibacterial activity both for the Gram-positive bacteria, Bacillus subtilis and Staphylococcus aureus and for the Gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa, but it lost such activity when heated at 75 degrees C for 5 min. The antibacterial factor of the snail mucus was a glycoprotein whose molecular weight (MW) was about 160,000. It was composed of two subunits of MW 70,000-80,000.     

Glycolipid composition of ascitic fluids from patients with cancer

The glycolipid composition of ascitic fluids from nine patients with cancer and one pleural effusion from a hepatoma patient was studied. Glucosylceramide, lactosylceramide, globotriaosylceramide, and globotetraosylceramide were found in all samples and also in normal human serum. These glycolipids accounted for more than 90% of the neutral glycolipid fraction and the composition in ascitic fluids was similar to that in normal human serum. From ascitic fluids, several minor glycolipids, which could not be detected in normal human serum, were isolated and characterized by exoglycosidase treatment. Lactoneotetraosylceramide was found in eight samples of ascitic fluids, and globopentaosylceramide was detected in two samples from hepatoma and one from pancreatic cancer. A fucolipid which was converted to lactoneotetraosylceramide by alpha-L-fucosidase treatment was recognized in two samples from hepatoma patients. In the ganglioside fraction, GM3 was the predominant component both in normal human serum and in ascitic fluid. The GM2 content in ascitic fluids was much higher than that in normal human serum. From these results, lactoneotetraosylceramide and GM2 are possible candidates as cancer markers, because they seemed to be derived from cancer tissues by shedding.     

Purification and characterization of a purple acid phosphatase from rat spleen

An acid phosphatase species which is activated by Fe2+ was purified 3,700-fold from rat spleen by chromatography on columns containing Blue-Sepharose, concanavalin A-Sepharose, Sephadex G-100, and CM-Sephadex. The enzyme hydrolyzed aryl phosphates, nucleoside di- and triphosphates, phosphoproteins, and thiamine pyrophosphate with Km values of 10(-4) to 10(-3) M at an optimal pH of 5.0-5.8. Co-purification of the acid phosphatase and acid phosphoprotein phosphatase indicated that they were identical. The purified enzyme was glycoprotein in nature, showing four heterogeneous forms on acid polyacrylamide gel electrophoresis (pI values, 7.8, 8.0, 8.3, and 8.5), but it gave a molecular weight of 33,000 on sodium dodecyl sulfate-gel electrophoresis and gel permeation chromatography. The enzyme had a purple color (lambda max 545 nm) and contained 2 iron atoms per enzyme molecule. Among reductants, ascorbic acid and Fe2+ were the best activators, although their combined effect was not additive. Fe2+ and ascorbic acid both changed the purple enzyme into the same active form (lambda max 515 nm), giving almost the same kinetic constants for substrates and for inhibitors such as molybdate, phosphate and fluoride. However, low concentrations of Fe2+, from 0.01 mM to 1.0 mM, immediately and reversibly activated the enzyme, whereas high concentrations of ascorbic acid over 1 mM were required for maximal activation, which was slow and irreversible.     

The alpha-form of S-adenosylmethionine synthetase isozymes from liver is principally functional

Treatment of rats with an ethionine plus adenine or a methionine diet leads not only to a marked increase of the alpha-form isozyme of S-adenosylmethionine synthetase in liver, but also to the accumulation of comparable amounts of S-adenosylethionine and S-adenosylmethionine in liver. Transplantation of ascites tumor cells into mice leads to a marked increase only of the beta-form isozyme in the host liver, but the levels of S-adenosylmethionine do not significantly change in liver.     

Incorporation of sialoglycoprotein containing lacto-series oligosaccharides into chicken asialoerythrocyte membranes and restoration of receptor activity toward hemagglutinating virus of Japan (Sendai virus)

Bovine erythrocyte sialoglycoprotein (GP-2) (1) containing lactoseries oligosaccharide chains, which showed highly specific inhibition of hemagglutination by HVJ (Hemagglutinating virus of Japan, Sendai virus), was incorporated into neuraminidase-treated chicken erythrocytes which had lost their biological responsiveness to the virus. The GP-2-incorporated erythrocytes were agglutinated and lyzed again by the virus. Incorporation of 1,900 molecules of GP-2 per asialoerythrocyte restored fairly well the susceptibility of the cells to HVJ-mediated agglutination and hemolysis. Treatment of the erythrocytes with neuraminidase again resulted in the complete abolishment of the response to HVJ. The above observations are consistent with the view that exogenous sialoglycoprotein, GP-2, can be functionally integrated into the surface membrane of asialoerythrocytes and serve as the receptor for HVJ during the initial adsorption-fusion phase of the virus infection of the target cells.     

Characterization of N-glycolyneuraminic acid-containing glycosphingolipids from a Marek's disease lymphoma-derived chicken cell line, MSB1, as tumor-associated heterophile Hanganutziu-Deicher antigens

Heterophile, Hanganutziu-Deicher (HD) antigen-active N-glycolylneuraminic acid-containing glycosphingolipids (GSLs) were detected as tumor-associated foreign antigens of a Marek's disease lymphoma-derived cell line, MSB1, by enzyme-immunoassay with chicken antibody against N-glycolylneuraminyl-lactosylceramide (anti-NeuGc-LacCer). At least three species of HD antigen-active GSLs were detected by two-dimensional thin-layer chromatography (TLC) combined with enzyme-immunoassay. The reactivities of the GSLs with anti-NeuGc-LacCer, their behaviors on two-dimensional TLC and the results of an endo-beta-galactosidase digestion study indicated that these three GSLs were NeuGc-LacCer (NeuGc alpha 2-2Gal beta 1-4Glc-Cer), NeuGc-nLcOse4Cer (NeuGc alpha 2-3Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc-Cer) and NeuGc-nLcOse6Cer (NeuGc alpha 2-3Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc-Cer).     

Periodic and non-periodic responses of a periodically forced Hodgkin-Huxley oscillator

Membrane potential responses of a Hodgkin-Huxley oscillator to an externally-applied sinusoidal current were numerically calculated with relation to bifurcation parameters of the amplitude and the frequency of the stimulating current. The Hodgkin-Huxley oscillator, or the Hodgkin-Huxley axon in the state of self-sustained oscillation of action potentials, was realized by immersing the axon in calcium-deficient sea water. The forced oscillations were analysed by the stroboscopic plots and/or the Lorenz plots. The results show that the periodically forced Hodgkin-Huxley oscillator exhibits not only periodic motions (harmonic or sub-harmonic synchronization) but also non-periodic motions (quasi-periodic or chaotic oscillation), that the motions were determined by the amplitude and the frequency of the stimulating current, and that the characteristic motions obtained in the present study were in reasonable agreement with those of our previous results, found experimentally in squid giant axons. Also, two kinds of routes to the chaotic oscillations were found; successive period-doubling bifurcations and formation of the intermittently chaotic oscillation from sub-harmonic synchronization.     

Identification of calmodulin in new-born rat calvaria

The extract of new-born rat calvaria was chromatographed on DEAE-cellulose. Calmodulin activity was eluted at 0.3 and 0.4 M NaCl and markedly inhibited by trifluoperazine and W-7, calmodulin antagonists. The fractions with calmodulin activity contained a protein the electrophoretic migration of which on sodium dodecyl sulfate-polyacrylamide gel was accelerated by Ca2+. Its apparent molecular weight was about 18 or 20K in the presence or absence of Ca2+, respectively. With 45Ca-autoradiography, the protein was shown to have a high affinity for Ca2+. Thus calmodulin could be readily identified in new-born rat calvaria.