PubMed Health⌕ Search

Biomedical subjects

G M Mackenzie

Publications and source records attributed to G M Mackenzie.

18 recordsLinked to original sources
PubMed2000

Osteoporosis. Recommended guidelines and New Jersey legislation.

More than 28 million Americans aged 50 and over have osteoporosis or low bone density. While 80% of those affected are women, one in eight men also suffer from the disease. This number is expected to increase as men live longer. Commonly called the "silent disease," osteoporosis exhibits no symptoms or pain until a fracture occurs. The most common fractures involve the wrist, vertebra, and hip. Half of all women and 20% of men will have at least one osteoporosis fracture in their lifetime. This article describes statewide efforts to prevent and manage osteoporosis and the recommended practice guidelines for the diagnosis and treatment of the disease.

Aged↗
PubMed1997

Morphology and electrophysiology of guinea-pig paratracheal neurones.

BACKGROUND: Although guinea-pig tracheal preparations are used as models of asthma, the morphological and electrophysiological characteristics of its associated ganglion neurones (paratracheal neurones) have not been characterized. METHODS: Intracellular staining and electrophysiological recording techniques have been applied to guinea-pig paratracheal neurones in isolated preparations. RESULTS: Most (32/35) neurones were multipolar, with many short (< 70 microns), finely tapering processes and one or more long processes; the latter, which were traced for up to 400 microns, travelled along the interconnecting nerve trunks, often in pairs, or over smooth muscle bundles. About 20% (6/32) of neurones had conspicuous somal extensions that gave rise to 3-8 processes. The soma morphology of neurones of the intrinsic ganglionated plexus close to the trachealis muscle were usually more complex than those in or associated with recurrent or vagal nerve trunks. Two types of neurone were identified electrophysiologically; neurones with fast excitatory synaptic potentials were found only in ganglia located very close to the smooth muscle, whereas > 90% of neurones lacking synaptic inputs were associated with recurrent nerve trunks. Transmural or focal electrical stimulation failed to evoke either slow inhibitory or slow excitatory (cholinergic or non-cholinergic) synaptic potentials in either electrophysiological type. CONCLUSIONS: It is tentatively concluded that the neurones of the intrinsic ganglionated plexus receiving synaptic input probably provided the para-sympathetic innervation to effector cells (such as trachealis muscle). Both these and the spiking neurones located in or near nerve trunks showed little potential for synaptic modulation of their excitability.

Animals↗
PubMed1997

Nitric oxide synthase inhibition and MPTP-induced toxicity in the common marmoset.

Nitric oxide, produced following activation of N-methyl-D-aspartate (NMDA) receptors, may be involved in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) toxicity since NMDA receptor antagonists have been shown to prevent MPTP induced nigral cell loss in primates. Common marmosets were treated with either saline or MPTP or L-NGnitro arginine methyl ester (L-NAME) or MPTP and L-NAME. MPTP-treated common marmosets showed motor deficits including bradykinesia, rigidity, and tremor accompanied by a marked loss of tyrosine hydroxylase-immunoreactive neurones in the substantia nigra pars compacta and of [3H]-mazindol binding in the caudate-putamen. MPTP treatment also caused an increase in glial fibrillary acidic protein (GFAP) staining in the substantia nigra compared to controls. However, MPTP treatment did not alter the number of constitutive nitric oxide synthase-immunoreactive neurones in the caudate-putamen. Furthermore, neurones or glial cells immunoreactive for inducible nitric oxide synthase were not observed in the substantia nigra pars compacta following MPTP treatment. L-NAME treatment alone did not produce any behavioural changes in marmosets and did not alter the number of tyrosine hydroxylase-immunoreactive cells in the substantia nigra pars compacta, the number of constitutive nitric oxide synthase-immunoreactive neurones or [3H]-mazindol binding in the caudate-putamen compared to saline-treated control animals. Furthermore, L-NAME did not affect the motor deficits, loss of tyrosine hydroxylase-immunoreactive neurones in the substantia nigra pars compacta, loss of [3H]-mazindol binding in the caudate-putamen, or the increase in GFAP staining in the substantia nigra induced by MPTP treatment of common marmosets. The failure of L-NAME to protect against MPTP-induced toxicity in the marmoset suggests that nitric oxide does not play a major role in such toxicity and casts doubt over the involvement of the NMDA:nitric oxide system in neurodegeneration in MPTP-treated primates.

Adrenergic Uptake Inhibitors↗
PubMed1975

The adrenal cortico-medullary ratio in the fowl.

1. A new integrating method of assessing the proportions of cortical and medullary tissue in the avian adrenal gland is described and statistically evaluated. 2. It is shown that a single "central" section of the adrenal gland will suffice to obtain accurate results. 3. Each section was projected on to a grid of about 2500 intersection points and the ratio of points falling on cortical or medullary tissue was determined. 4. Applications of this method to normal fowls showed that there were significant breed, sex and, particularly, age differences in the cortico-medullary ratio of the fowl's adrenal glands.

Adrenal Cortex↗