Effect of exercise training on the chronotropic response of isolated rat atria to atropine

Summary Atria isolated from rats after 7 weeks of exercise training beat at a slower rate than did atria from sedentary controls. Atria from exercised rats showed a significant acceleration in response to atropie.This study was supported by a grant from the Genesee Valley Heart Association.     

Presence in immunostimulated cells of an RNA molecule utilizable as template for reverse transcriptase of avian myeloblastosis virus (AMV)]

Cytoplasmic RNA extracted from antigen stimulated immunocompetant cells is transcribed in vitro into DNA by the RNA directed DNA polymerase from avian myeloblastosis virus, in the absence of any added primer. Cytoplasmic RNA from other organs of the same animal, from non-stimulated immunocompetent cells, or from cells in tissue culture is not transcribed in the absence of exogenous primer.     

Regular oscillations in suspensions of a putatively chaotic mutant of Dictyostelium discoideum

We have tested the light-scattering properties of suspensions of the Dictyostelium discoideum mutant HH201 derived from the mutant Fr17. Previous studies indicated that HH201 and Fr17 possess highly irregular rhythmic properties which might represent aperiodic oscillations, i.e. chaos. We report that the former mutant can display regular oscillatory behavior. Possible explanations for this result are discussed, including that of a transition from chaotic to periodic behavior resulting from some parameter change or from strong intercellular coupling in cell suspensions.     

Properties of the laccase of Botrytis cinerea]

Laccase from Botrytis cinerea, secreted by the fungus into the grape berry, is responsible for the oxidation phynomena in musts and wines (oxidasic casse). From a fungus culture, the enzyme was extracted for a study of its properties: specificity; influence of inhibitors, pH and temperature; The results confirm that the enzyme from Botrytis cinerea belongs to the laccase family, though it has some characteristic differences from the other laccases previously described.     

Isolation of the yellow fever virus from an egg-cluster and the larvae of the tick Amblyomma variegatum]

The yellow fever virus is isolated in natura from eggs of a Tick Amblyomma variegatum. It is then isolated from larvae issued from the same egg-cluster and also from blood of a monkey bitten by larvae of the same origin. It is reported that the same virus has been previously obtained from adults of the same species of Tick. An acarine appears for the first time as a sylvatic vector and reservoir (at least temporary) of yellow fever.     

Stereospecificity of hydrogen transfer of aldehyde reductase

Summary Aldehyde reductase from human liver catalyzes the hydrogen transfer from the pro-4R position on the dihydronicotinamide ring of the coenzyme to there face of the carbonyl carbon atom of the substrate.     

Macrophage origin of platelet activating factor]

Platelet-activating factor (P.A.F.) is a mediator of anaphylaxis released from human and Rabbit basophils which causes aggregation of platelets and release of their vasoactive amines. We have induced the release of P.A.F. from Rat peritoneal cells (P.C.) with ionophore A 23187. After fractionation of P.C. on 5-15% Ficoll gradients, P.A.F. was obtained from macrophage-rich but not from mastocyte-rich fractions and from adherent cells but not from non adherent cells. These data suggest an important new function for the macrophage: aggregation of platelets and release of their vasoactive amines and others mediators of inflammation.     

Lymphatic metastasis of tumour; persistent transport of cells.

A model of lymphatic metastasis established by injecting Walker rat carcinoma cells into the rat footpad was used to study the output of tumour cells from the footpad. The lymphatic efferent from the footpad was cannulated in a group of rats with advanced neoplasm; it was shown that the output of tumour cells was continuous over periods up to 90 min and ranged from 10(2)-10(5) cells/min.     

Polymerization of phenolic intermediates of pesticides by a fungal enzyme.

The fungus Rhizoctonia praticola produces an extracellular phenol oxidase (laccase) which polymerizes phenolic intermediates of various pesticides. The enzyme catalyzes the formation of oligomeric products from halogenated phenolic intermediates of phenoxyalkanoate herbicides and from naphtholic products derived from carbamate insecticides. These findings permit further investigations into the mechanism and role of oxidative coupling leading to the incorporation of xenobiotic compounds into soil organic matter.     

Inhibitor of the oxidation of catechin released from the roots of corn seedlings

Summary When the specific activities of the catechin oxidases (catechin as the substrate) which were released from the roots of the seedlings of alfalfa, tomato, wheat, lettuce and corn were compared, it was found that the oxidizing activity was absent from the root exudate of corn seedlings. A 6.3 kDa protein was purified from the root exudate of corn seedlings and in the presence of this protein, the oxidation of catechin was inhibited. This inhibitor is responsible for the inability of the root exudate of corn seedlings to oxidize catechin.     

Conformational stability and basal metabolic rate: Reexamination of the case of myoglobin

Summary The free energy of unfolding of several myoglobins from different animal species has been determined from their denatunation pattern by using the ligand binding model. The results indicate that no simple correlation exists between the free energy of unfolding of myoglobin and the basal metabolic rate of the animal species from which the myoglobin was isolated     

Comparison of the effects of concanavalin A on cell growth and the transport of 3-O-methylglucose in chick embryo fibroblasts

The proliferative capacity of Chick embryo fibroblasts was modified by Con A treatment. Con A decreased the growth of fibroblasts from young embryos (8 days), whereas the lectin stimulated the growth of fibroblasts from older embryos (16 days). This differential effect of Con A did not result from changes in cellular permeability to thymidine, but rather from Con A induced modifications of hexose transport. Changes in hexose transport would cause, as a response, parallel modifications in glycolysis and hence energy charge, which would alter proliferative capacity.     

Stereospecificity of hydrogen transfer of aldehyde reductase.

Aldehyde reductase from human liver catalyzes the hydrogen transfer from the pro-4R position on the dihydronicotinamide ring of the coenzyme to the re face of the carbonyl carbon atom of the substrate.     

Lack of influence of vitamin D deficiency on insulin release from the isolated pancreatic islets of rats

Pancreatic islets were isolated from young (100 g) and adult (390 g), normal and vitamin D deficient male Sprague-Dawley rats. The release of insulin from leucine-stimulated or glucose-stimulated islet was not altered by vitamin D deficiency. The in vitro addition of either 25-hydroxy- or 1,25-dihydroxyvitamin-D had no effect on insulin release from either normal or vitamin D deficient islets. We conclude that the earlier report (Normal et al., Science 209 (1980) 823-825) on vitamin D deficiency depressing insulin secretion from the perfused pancreas must be related to the vitamin's effect on insulin synthesis and not the islet's release of insulin.     

Conformational stability and basal metabolic rate: reexamination of the case of myoglobin

The free energy of unfolding of several myoglobins from different animal species has been determined from their denaturation pattern by using the ligand binding model. The results indicate that no simple correlation exists between the free energy of unfolding of myoglobin and the basal metabolic rate of the animal species from which the myoglobin was isolated.     

Microclimatic origin of inhaled air affects olfactory navigation of homing pigeons

Earlier experiments led to the conclusion that homing pigeons are able to deduce positional information from atmospheric odours they perceive at the site of release. Here we show that this ability is significantly reduced, if the inhaled air does not originate from the free airspace in an open landscape but from a close-to-the-ground level of a forest or a maize field.     

Polymerization of phenolic intermediates of pesticides by a fungal enzyme

Summary The fungusRhizoctonia praticola produces an extracellular phenol oxidase (laccase) which polymerizes phenolic intermediates of various pesticides. The enzyme catalyzes the formation of oligomeric products from halogenated phenolic intermediates of phenoxyalkanoate herbicides and from naphtholic products derived from carbamate insecticides. These findings permit further investigations into the mechanism and role of oxidative coupling leading to the incorporation of xenobiotic compounds into soil organic matter.     

Electron microscopy of mitochondrial DNA in Podospora anserina and the presence of a multimeric range of circular DNA molecules from senescent cultures]

Mitochondrial DNA from young cultures of race s of Podospora anserina was isolated. Its density in Cesium chloride density equilibrium gradients was 1.694 g/cc. Examination by the electron microscope revealed that ca 1% of this DNA consisted of circles, 31 micrometer in contour length; the remaining DNA was composed of linear molecules ranging in length from 2 to 33 micrometer. In DNA of similar density obtained from senescent cultures of the same race s, about 11% of the molecules consisted of a multimeric set of circles ranging in size from 0.9 to 15 micrometer, with most being in the 1.8 and 2.7 micrometer classes. The similarity of these DNA molecules with the mitochondrial DNA from rho(-) yeast mutants is discussed.     

Spleen antibacterial peptides: high levels of PR-39 and presence of two forms of NK-lysin

Antibacterial peptides were isolated from porcine spleen by acetic acid extraction, ion exchange chromatography and reverse-phase high-performance liquid chromatography. C-terminal ladder sequence analysis of a bioactive peptide with matrix-assisted laser desorption/ionization mass spectrometry after digestion with carboxypeptidases P and Y showed that it is identical to the antibacterial proline/arginine-rich intestinal peptide PR-39. It is present at high levels in granulocytes of the spleen, and peptides with C-terminal proline amide and internal adjacent Pro residues can be analyzed with this method. In addition, two forms of NK-lysin (NKL) were found. One, NKLi, is identical to that isolated from pig intestine, and the other, NKLbw, to a mature peptide deduced from a clone from a porcine bone marrow cDNA library.     

Detection of human cytomegalovirus (HCMV) DNA from cell-free plasma of immunosuppressed patients by nested PCR: influence of nucleic acid extraction method

Conclusions Blood cells and plasma preparations from HCMV-seropositive healthy blood donors were all nPCR negative. Detection of HCMV DNA from PBMC and granulocytes (DNAemia) of immunosuppressed patients by nPCR did not correlate with the isolation of infectious virus from these cell populations in cell culture (viremia). However HCMV could be isolated in 60% of cases from other materials of the same patient. HCMV DNA detected in blood cells persisted for up to one year in an asymptomatically infected individual after NTX. The sensitivity of HCMV DNA detection in cell-free plasma (up to 5 fg) depended on the method used for DNA isolation. The rate of HCMV DNA detection in plasma was lower than in leukocytes. In all cases of positive plasma PCR infectious virus could be isolated from any other material of the symptomatically infected patients. Therefore HCMV DNA PCR from plasma of immunosuppressed patients seems to be a suitable and easy alternative to HCMV RT/PCR for routine diagnosis of HCMV disease.