Effect of unilateral decortication on acetylcholine release from the nucleus basalis.

Acetylcholine (ACh) is released from the rat nucleus basalis magnocellularis (nbM) following tissue depolarization with 35 mM K+. In the present study, we report that cholinergic neurons within the nbM undergo retrograde changes resulting in a significant reduction in K+-evoked ACh release following cortical lesions.

Acetylcholine content and distribution in rat cortical synaptosomes after in vivo exposure to quinolinic acid.

In this study, changes in the concentration and subcellular distribution of rat cortical synaptosomal acetylcholine (ACh) was investigated after a single injection of quinolinic acid (QUIN) into the nucleus basalis magnocellularis (nbM). In the P2 fraction of normal animals the ACh concentration was 235 +/- 18 pmol/mg protein. Of this, 64 +/- 10% was recovered in the particulate (P3) fraction and 24 +/- 1% in the soluble (S3) fraction. Cortical synaptosomes (P2) prepared 0.5 h after injecting either 600 or 1000 nmol of QUIN contained significantly higher concentrations of ACh (372 +/- 127 and 496 +/- 77 pmol/mg protein, respectively) when compared to the amount of ACh in control animals. The ACh concentration in the P2 fraction was still elevated 3 h after injecting 600 nmol QUIN, however, synaptosomal ACh decreased significantly 3 h after rats were treated with 1000 nmol QUIN. Determination of subcellular ACh 0.5 h after injecting QUIN revealed that neither dose of QUIN produced a change in the distribution of ACh between P3 and S3. However, 3 h after injecting QUIN, a shift in the subcellular distribution of ACh to the cytoplasmic fraction (S3) was observed with 1000 nmol QUIN. These results show that QUIN-induced depolarization of nbM neurons which project to the cortex produce both dose-dependent and time-dependent changes in synaptosomal ACh concentration and subcellular distribution.

The release of endogenous acetylcholine from the medial septum/diagonal band of rat brain.

This study sought to establish whether cholinergic neurons in the medial septum/vertical limb of the diagonal band (ms/vdB) release endogenous acetylcholine (ACh) locally, and whether the release was modulated by presynaptic feedback mechanisms. Release of ACh from slices of the ms/vdB was assessed by gas chromatography-mass spectrometry (GC-MS). Potassium depolarization resulted in a 20- to 25-fold increase in ACh release above spontaneous levels. Omission of Ca2+ from the incubation medium decreased this release by 91%. In the presence of 4 microM atropine, potassium-induced ACh release was enhanced by 48%. These results indicate that ACh is released in the ms/vdB by a Ca2+-dependent and atropine-sensitive process.

Release of acetylcholine from tissue slices of the rat nucleus basalis magnocellularis.

We investigated the release of acetylcholine (ACh) from tissue slices obtained from the nucleus basalis magnocellularis (nbM) of the rat brain. Potassium (35 mM) depolarization produced a 10- to 12-fold increase in the release of endogenous ACh above spontaneous release. Potassium-evoked ACh release was Ca2+ dependent. Injection of the excitotoxin quinolinic acid into the nbM produced a 72.8 +/- 13.0% decrease in spontaneous ACh release and a 60.4 +/- 8.2% decrease in potassium-evoked release. A fourfold increase in ACh release was observed following perfusion of the tissue with 1 mM 3,4-diaminopyridine (3,4-DAP) whereas 10 mM 3,4-DAP caused a sevenfold increase. The increase in ACh release caused by 3,4-DAP was inhibited by tetrodotoxin. Tissue slices accumulated [3H]choline by high-affinity choline uptake and this could be inhibited by hemicholinium-3. These results indicate that ACh can be released from tissue slices of the nbM by a calcium-dependent process and that a part of this release appears to be from the cholinergic neurons of the nbM.

Pasteurization of naturally contaminated water with solar energy.

A solar box cooker (SBC) was constructed with a cooking area deep enough to hold several 3.7-liter jugs of water, and this was used to investigate the potential of using solar energy to pasteurize naturally contaminated water. When river water was heated either in the SBC or on a hot plate, coliform bacteria were inactivated at temperatures of 60 degrees C or greater. Heating water in an SBC to at least 65 degrees C ensures that the water will be above the milk pasteurization temperature of 62.8 degrees C for at least an hour, which appears sufficient to pasteurize contaminated water. On clear or partly cloudy days, with the SBC facing magnetic south in Sacramento, bottom water temperatures of at least 65 degrees C could be obtained in 11.1 liters of water during the 6 weeks on either side of the summer solstice, in 7.4 liters of water from mid-March through mid-September, and in 3.7 liters of water an additional 2 to 3 weeks at the beginning and end of the solar season. Periodic repositioning of the SBC towards the sun, adjusting the back reflective lid, and preheating water in a simple reflective device increased final water temperatures. Simultaneous cooking and heating water to pasteurizing temperatures was possible. Additional uses of the SBC to pasteurize soil and to decontaminate hospital materials before disposal in remote areas are suggested.

Enhancement of solar water pasteurization with reflectors.

A simple and reliable method that could be used in developing countries to pasteurize milk and water with solar energy is described. A cardboard reflector directs sunshine onto a black jar, heating water to pasteurizing temperatures in several hours. A reusable water pasteurization indicator verifies that pasteurization temperatures have been reached.

Staphylococcus aureus response to lysostaphin in some fermented foods.

The addition of lysostaphin to starting materials for cheese and fermented sausage that were artificially contaminated with Staphylococcus aureus resulted in an initial decrease in the staphylococcal flora. In a simulated cheese process, lysostaphin remained with the curd after separation of the whey. In both cheese and fermented sausage samples that were produced experimentally in the laboratory, a significant S. aureus population ultimately developed, even in the presence of lysostaphin. Staphylococcal isolates from these treated products were not more resistant to the lytic enzyme than was the parent strain.

Differential lytic response of enterococci associated with addition order of lysozyme and anions.

Suspensions of Streptococcus faecium, prepared by washing with and resuspending in water, were lysed slowly if sodium chloride was added prior to lysozyme; however, if brief incubation with lysozyme was followed by addition of sodium chloride, lysis was immediate and extensive. Relatively lysozyme-resistant strains of S. faecalis could be lysed readily by adding lysozyme first. The primary addition of lysozyme apparently resulted in a "sensitized" cell with a damaged wall, as evidenced by N-acetylhexosamine release. Anionic detergents could replace sodium chloride in lysing these sensitized cells. The difference in activity associated with the order of addition probably involved a competition for reactive sites on the cell surface.

Growth of Streptococcus faecium in the presence of lysozyme.

Streptococcus faecium can grow normally in the presence of lysozyme, despite the observation that cell suspensions of the organism are lysed readily by the enzyme. Growth in the presence of lysozyme is not due to resistant cells, and the culture is lysed after growth if the pH of the medium is not allowed to drop too low for lysozyme activity. Growth followed by lysis in the presence of lysozyme was not exhibited by other organisms tested which were either significantly more resistant or more sensitive to lysozyme than S. faecium. Lysozyme was active on the cell wall of S. faecium during growth in the presence of 200 mug of the enzyme per ml in a complex medium. It appears that, when actively metabolizing, S. faecium can synthesize the cell wall at a greater rate than lysozyme can hydrolyze it. Thus, the organism is capable of growth in the presence of the enzyme. A large variation in the lytic responses of enterococcal cell suspensions to lysozyme was dependent on the strain used, the growth phase from which the culture was harvested, and the medium in which the culture was grown.

Effect of lysozyme on enterococcal viability in low ionic environments.

The action of lysozyme on the enterococcal cell differed markedly as a function of the ionic strength of the environment. In high ionic environments (I approximately 0.3), the traditionally slow lytic response and decrease in viability were noted. In a low ionic environment the majority of the cell wall was hydrolyzed, but cellular integrity was preserved and almost all cellular protein, deoxyribonucleic acid and ribonucleic acid remained with the lysozyme-cell complex. However, under these conditions, lysozyme inactivated energy-yielding metabolism, and a rapid extensive loss of viability was observed. Some other basic compounds without lytic activity on the cell wall also effected a substantial reduction in viability. The data suggest that lysozyme acts on the cell membrane to effect disruption of cellular metabolism.

Effect of quinolinic acid in the nucleus basalis magnocellularis on cortical high-affinity choline uptake.

A transient 45% increase in cortical high-affinity choline uptake (HACU) was observed after an injection of quinolinic acid (QUIN) into the nucleus basalis magnocellularis (nbM) of the rat. This was followed by a steady decline in choline uptake, which resulted in a 46% decrease by day 7. Specific [3H]hemicholinium-3 binding to coronal brain sections showed a similar pattern following injections of QUIN into the nbM. The increase in cortical HACU elicited by QUIN appeared to be dose dependent.