Vasoactive intestinal peptide: a possible transmitter of nonadrenergic relaxation of guinea pig airways

Vasoactive intestinal peptide, a smooth-muscle relaxant neuropeptide with neurotransmitter properties, was relaxed during electrical field stimulation of guinea pig trachea. The amount released correlated with the degree of relaxation, and the release was blocked by tetrodotoxin. Prior incubation of the trachea with antiserum to vasoactive intestinal peptide reduced the relaxation. Thus vasoactive intestinal peptide may mediate the nonadrenergic relaxation of tracheal smooth muscle.     

Vasoactive intestinal peptide alters membrane potential and cyclic nucleotide levels in retinal horizontal cells

Vasoactive intestinal peptide stimulated the synthesis of adenosine 3',5'-monophosphate in fractions of isolated carp horizontal cells. When applied extracellularly to isolated and cultured horizontal cells, the peptide also induced a slow depolarization (30 to 40 millivolts) accompanied by a decrease in membrane resistance. However, analogs of adenosine 3',5'-monophosphate applied extracellularly or intracellularly, and forscolin applied extracellularly, had no effect on the membrane potential of cultured horizontal cells, indicating that the induced depolarization was not related to the accumulation of adenosine 3',5'-monophosphate in these cells.     

Synaptic transmission in the crayfish: increased release of transmitter substance by bacterial endotoxin

Bacterial endotoxin increases the frequency of miniature excitatory postsynaptic potentials, decreases facilitation, and increases the evoked excitatory postsynaptic potential without changing membrane resistance. These data indicate that endotoxin acts on the presynaptic nerve terminal by increasing the amount of transmitter substance released in response to an applied stimulus.     

Vasoactive intestinal polypeptide and muscarinic receptors: supersensitivity induced by long-term atropine treatment

Long-term treatment of rats with atropine induced large increases in the numbers of muscarinic receptors and receptors for vasoactive intestinal polypeptide in the salivary glands. Since receptors for vasoactive intestinal polypeptide coexist with muscarinic receptors on the same neurons in this preparation, the results suggest that a drug that alters the sensitivity of one receptor may also affect the sensitivity of the receptor for a costored transmitter and in this way contribute to the therapeutic or side effects of the drugs.     

Calcium: is it required for transmitter secretion?

Ethanol multiplies miniature end-plate potential frequency independently of calcium ion concentrations and also multiplies calcium-dependent depolarization-evoked quantal release, to the same extent. This result implies a final common pathway, requiring little or no calcium, for both kinds of transmitter secretion. Chlorpromazine and hypertonicity act similarly to ethanol, but also depress depolarization-secretion coupling.     

Temperature in the monkey: transmitter factors released from the brain during thermoregulation

When perfusate is collected from the anterior hypothalamus of a cooled donor monkey and is transfused to a corresponding hypothalamic site in a normal monkey, fever occurs in this recipient. Conversely, perfusate from a heated donor monkey lowers the recipient monkey's temperature when the same hypothalamic transfusion procedure is followed. These experiments provide direct evidence of a neurochemical "coding" within the specific anatomical region of the brain historically implicated in the control of body temperature.     

Science centers: a potential for learning

The past decade has witnessed a proliferation of science-technology centers, or public places for informal learning about science and technology. Science centers are the only institutions that can provide the general public with participatory exhibits and experiences, together with an accurate scientific interpretation of the materials that are involved. The dramatic rise in attendance and the enthusiasm of repeat visitors to science centers reflect a strong public demand for exhibits designed to help the visitor develop a better understanding of the contemporary scientific issues of society.     

Sweat in schizophrenic patients: identification of the odorous substance

The substance causing the peculiar odor in sweat of schizophrenic patients has been isolated and identified as trans-3-methyl-2-hexenoic acid by gas chromatography, mass spectrometry, and nuclear magnetic resonance spectroscopy. The natural and the synthetic compounds were cleaves across the double bond to give 2-pentanone and oxalic acid, thereby confirming the structure.     

Very-low-density lipoprotein in intestinal lymph: evidence for presence of the A protein

Rat mesenteric lymph very-low-density lipoproteins of intestinal origin contain components which are antigenically identical to plasma high-density lipoprotein. Because the antigenicity of the latter most likely resides in its apoprotein (the A protein), it is concluded that intestinal very-low-density lipoproteins contain the A protein. This and other evidence supports the concept that the intestine is a source of plasma very-low-density lipoprotein.     

Melatonin, a pineal substance: effect on the rat ovary

Daily injection of microgram amounts of melatonin in rats decreased the incidence of estrus and reduced ovarian weight. Circulating melatonin was selectively taken up and retained by the ovary and pineal gland; this effect was reduced by exposure of rats to constant light. A single injection of melatonin lowered the incidence of estrus among rats exposed to constant light.     

The potential for grass-fed livestock: resource constraints

Using pasture and grazed forest-range for a system of producing live-stock by feeding grass alone reduces the inputs of energy about 60 percent and land resources about 8 percent, but also reduces by about half the production of animal protein in the United States. Under a system in which only grass was fed, livestock would be restricted to beef, milk, and lamb production. The amount of grain fed to U.S. livestock is about 135 million tons (metric) or about ten times the amount consumed by the U.S. population.     

A transgenic model for listeriosis: role of internalin in crossing the intestinal barrier

Listeria monocytogenes is responsible for severe food-borne infections, but the mechanisms by which bacteria cross the intestinal barrier are unknown. Listeria monocytogenes expresses a surface protein, internalin, that interacts with a host receptor, E-cadherin, to promote entry into human epithelial cells. Murine E-cadherin, in contrast to guinea pig E-cadherin, does not interact with internalin, excluding the mouse as a model for addressing internalin function in vivo. In guinea pigs and transgenic mice expressing human E-cadherin, internalin was found to mediate invasion of enterocytes and crossing of the intestinal barrier. These results illustrate how relevant animal models for human infections can be generated.     

Insulin: carrier potential for enzyme and drug therapy

Several carrier systems and targeting agents have been considered as means of delivering enzymes and drugs to specific tissues or cells. In this report insulin is shown to be effective in delivering enzyme-albumin conjugates to cells and tissues rich in insulin receptors. The complex is transported into cells by a process that resembles receptor-mediated endocytosis and can be identified in a lysosomal fraction. The enzyme-albumin-insulin complex retains its enzymatic activity and its ability to bind antibodies to insulin. It also has a hypoglycemic effect; however, plasma glucose concentrations can be maintained by glucose administration.     

Release of slow-reacting substance of anaphylaxis in the rat: polymorphonuclear leukocyte

The antigen-induced release of slow-reacting substance of anaphylaxis was studied in rats previously treated with different biological and pharmacological agents to deplete these animals of specific cellular elements. The polymorphonuclear leukocyte appears necessary as a crucial cell type for optimum release of the slow-reacting substance of anaphylaxis, whereas the mast cell and lymphocyte are not required.