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Biomedical subjects

M A Gillis

Publications and source records attributed to M A Gillis.

6 recordsLinked to original sources
PubMed2001

Monoamine release by neurons of a primitive nervous system: an amperometric study.

We measured monoamine release from dissociated neurons of the sea pansy Renilla koellikeri, a representative of the most evolutionarily ancient animals with nervous systems, by real-time monitoring of exocytosis using the amperometric method with carbon-fiber microelectrodes. Depolarization-induced, as well as spontaneously active, neurons exhibited calcium-dependent exocytotic events at both the soma and the terminal bulb of neuritic processes. All spontaneously active neurons exhibited a bursting activity pattern in which amplitudes of exocytotic events appeared to be distributed in a quantal-like fashion. Fast Fourier transform analysis of bursting activity in 20 such neurons revealed burst harmonics with a major frequency of 8 Hz and a dominant rate of 95 Hz for individual exocytotic events within bursts. The results suggest that exocytotic transmitter release is as ancient as neurons and that endogenously bursting neurons in the sea pansy are as complex as those of higher animals. In addition, the observation that both soma and neuritic terminals of the same neuron can release transmitter suggests that local release sites in these cnidarian neurons are not critical for nerve net function.

Animals↗
PubMed1999

Using reflective thinking to develop personal professional philosophies.

Reflective thinking, closely related to critical thinking, is discussed as an essential teaching-learning process to help students in introductory professional courses develop personal professional philosophies. Reflective thinking opportunities used by nurse educators and teacher educators include students' own experiences, actual case studies, and media presentations. Using reflective thinking to develop personal professional philosophies helps students view themselves as future participants in their chosen professions.

Education, Nursing, Baccalaureate↗
PubMed1983

Acute effects of aspartame on large neutral amino acids and monoamines in rat brain.

The dipeptide aspartame (APM; aspartylphenylalanine methylester), an artificial sweetener, was studied in vivo for its ability to influence brain levels of the large neutral amino acids and the rates of hydroxylation of the aromatic amino acids. The administration by gavage of APM (200 mg/kg) caused large increments in blood and brain levels of phenylalanine and tyrosine by 60 minutes. Brain tryptophan level was occasionally reduced significantly, but the brain levels of the branched-chain amino acids were always unaffected. Smaller doses (50, 100 mg/kg) also raised blood and brain tyrosine and phenylalanine, but did not reduce brain tryptophan levels. At the highest dose (200 mg/kg), APM gavage caused an insignificant increase in dopa accumulation (after NSD-1015), and a modest reduction in 5-hydroxytryptophan accumulation. No changes in the brain levels of serotonin, 5-hydroxyindoleacetic acid, dopamine, dihydroxyphenylacetic acid, homovanillic acid, or norepinephrine were produced by APM administration (200 mg/kg). These results thus indicate that APM, even when administered in amounts that cause large increments in brain tyrosine and phenylalanine, produce minimal effects on the rates of formation of monoamine transmitters.

Amino Acids↗
PubMed1981

Reduction in brain serotonin synthesis rate in streptozotocin-diabetic rats.

The rate of serotonin synthesis in brain was determined in streptozotocin-diabetic and normal rats using two methods. Both the rate of 5-hydroxytryptophan accumulation after aromatic amino acid decarboxylase inhibition, and the decline rate of 5-hydroxyindole acetic acid after pargyline treatment were significantly reduced in diabetic rats. The reduced rate of synthesis may be a direct result of significantly lowered brain tryptophan levels in diabetic rats.

Animals↗
PubMed1980

Radioimmunologic detection and measurement of nonapeptides in the pineal gland.

RIAs have been developed for the nonapeptide hormones arginine vasotocin (AVT), arginine vasopressin (AVP), and oxytocin (OT). The AVP RIA can detect as little as 2 pg hormone and shows essentially no cross-reactivity with AVT or OT. The OT RIA is sensitive to 7 pg and shows no significant cross-reactivity with AVP or AVT. The AVT RIA is sensitive to about 5 pg; some cross-reactivity occurs with OT and AVP, but the RIA is suitable for assaying AVT levels in biological samples containing OT and/or AVP in concentrations up to 5 times greater than that of AVT. Using these RIAs, we found large amounts of AVT (up to 1.48 microgram/gland) in the chicken pituitary but no AVP or OT. The chicken pineal also contained AVT (about 300 pg/gland) and lacked AVP and OT. Bovine pineal glands appeared to contain all three peptides in roughly similar amounts (200-400 pg/gland). Pineal glands from a variety of rodents (including the rat) contained only very small amounts of AVT-like immunoreactivity (about 10 pg/gland) and no AVP or OT. Because AVT immunoreactivity appears in the pineals of several species, the peptide may subserve some physiological function of this organ. The functional roles, if any, of AVP and OT in the bovine pineal are unknown.

Animals↗