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Biomedical subjects

M R Martin

Publications and source records attributed to M R Martin.

At least 37 records · Page 2Linked to original sources
PubMed1981

Histogenesis of the cochlear nucleus of the mouse.

In Nissl-stained preparations of the cochlear nucleus there are nine recognizable cell types. These cells are born during three periods of histogenesis prenatally. On gestation days 10.0, 10.5, and 11.0 the pyramidal, giant, and dark-staining cells are born. The spherical, globular, multipolar, and horizontal cells are formed on gestation days 12.0, 12.5, and 13.0 and small cells follow on gestation day 14.5. The onset of granule cell formation is gestation day 14.5 continues to birth on gestation day 19. At birth, and for at least the first 2 postnatal weeks, glial cells are born. There are no regional gradients in cell birth dates, cells from all birth dates being intermixed. Cell birth proceeds in an orderly sequence that is related only to cell size. Although there were no apparent spatiotemporal patterns, some clustering of labeled cells was evident. These observations do not support the hypothesis that Golgi Type I cells precede Golgi Type II cells in their order of birth since both large and small neurons project beyond the nucleus. There is, nonetheless, a sequential pattern in the onset of cell birth for the auditory system, with cochlear nucleus neurons preceding cochlear neurons.

Aging↗
PubMed1981

Sideroblastic anaemia in association with malignant histiocytosis.

A 69-year-old women died of malignant histiocytosis in association with sideroblastic anaemia. Respiratory insufficiency was a prominent clinical feature and was found to be due to obstruction of pulmonary capillaries by malignant histiocytes. It is possible that the same abnormal myeloid clone gave rise to malignant histiocytosis and sideroblastic anaemia.

Aged↗
PubMed1980

Effects of D,L-alpha-aminoadipate on postsynaptic amino acid responses in cultured mouse spinal cord neurons.

The effects of the dicarboxylic amino acid, DL-alpha-aminoadipate (DLAA) on amino acid responses have been investigated using intracellular recordings from mouse spinal cord neurons grown in dissociated cell culture. DL-alpha-Aminoadipate markedly antagonized postsynaptic responses to iontophoretically appllied aspartate; antagonism of glutamate was much less prominent. DL-alpha-Aminoadipate altered the affinity of aspartate for its receptor while having no observed effects on aspartate-receptor cooperativity. No direct effects of DLAA on membrane potentials or passive membrane properties were seen at the currents used for antagonism. Responses to the inhibitory amino acids GABA and glycine were unaffected by DLAA.

2-Aminoadipic Acid↗
PubMed1979

Maternal deaths in South Australia 1970 to 1975.

During the period from 1970 to 1975 there were 128 087 confinements in South Australia and 30 maternal deaths were reported, representing a maternal mortality rate of 23 per 100 000 confinements which is lower than in previous reports. Twenty-one deaths were directly due to complications of pregnancy and childbirth, and nine were due to associated conditions. The fall in the maternal mortality rate was largely due to a reduction in the number of deaths from abortion and in the number of confinements to women in the higher-risk older age groups. Infection appeared for the first time as a major cause of maternal death. Avoidable factors may have contributed to 47% of the deaths.

Abortion, Spontaneous↗
PubMed1978

Quisqualamine, a novel gamma-aminobutyric acid (GABA) related depressant amino acid.

A new substnace, quisqualamine, the decarboxylated analogue of quisqualic acid, predictably depressed electrical activity of neurons of the frog and rat spinal cord in vitro and of the mouse spinal cord in vivo. In the in vitro preparations, the action of quisqualamine was associated with a prolonged depolarization of primary afferent terminals which was sensitive to blockade by picrotoxin and bicuculline and which was also depressed by strychnine. This suggests an interaction of quisqualamine with presynaptic receptors for both GABA and beta-alanine. Post-synaptic actions of quisqualamine, which were less marked than those at presynaptic sites, also appeared to be predominantly GABA-mimetic in vitro, though a sensitivity to the GABA-antagonist bicuculline could not be demonstrated in vitro.

Amines↗
PubMed1977

Electrophysiological studies on interpositus neurones in the normal and Lurcher mutant mouse.

The response characteristics of interpositus neurones (IP) to sciatic nerve stimulation were studied in normal and Lurcher mutant mice under pentobarbitone anaesthesia. The response of IP neurones in the normal mouse was a short latency bimodal excitation (E1-I1-E2) followed by a depression of the firing rate (I2) and ending with a longer latency excitation (E3) which was completed within 225 msec. The response of the majority of IP neurones in the Lurcher mouse was a short latency unimodal excitation (LE1) which corresponded in time to the E1-I1-E2 phase in the normal. This was followed by a pause in the excitation. The response ended with a longer latency excitation (LE2) corresponding in time to the E3 phase in the normal mouse but which persisted for a considerably greater period of time. The response of IP neurones in normal and Lurcher mice appear to be similar to those observed in the normal and experimentally cerebellar decorticate cat, respectively.

Animals↗
PubMed1977

Pharmacological studies of facial motoneurones in the rat.

Experiments were performed on 39 male albino rats anaesthetized with pentobarbitone sodium and paralyzed with gallamine triethiodide. Facial motoneurones consistently showed a progressive alteration of spike shape and decrease in spike firing frequency during the continuous microelectrophoretic application of the excitant amino acids D,L-homocysteate, L-glutamate, L-aspartate, and kainate, but infrequently during that of N-methyl-D-aspartate. The relative potencies of these excitants on facial motoneurones are reported. The potential usefulness of N-methyl-D-aspartate to produce amino acid-evoked motoneurone action potentials is discussed. The microelectrophoretically-applied depressant amino acid antagonist strychnine selectively and reversibly blocked the depressant effects of glycine on facial motoneurones. The depression of amino acid-induced firing of facial motoneurones by stimuli to the lingual or glossopharyngeal nerves were reversibly antagonized by microelectrophoretically applied strychnine but not by bicuculline.

Action Potentials↗
PubMed1977

Morphology of the facial nucleus of the rat.

The facial nucleus of the rat can be divided into 5 morphological subdivisions. Using a method for the correlation of the observed subdivisions with antidromic field profiles, the orgins of the major muscle branches of the facial nerve in the motor nucleus were determined. The posterior auricular branch is in the medial, the cervical in the ventromedial, the inferior and superior buccolabiales in the lateral, the zygomatic in the dorsal and the temporal and digastric in the intermediate subdivision. The results are consistent with an organization of the motor nucleus reflecting a corresponding topographic organization of the facial musculature.

Animals↗
PubMed1977

The seventh cranial nerve of the rat. Visualization of efferent and afferent pathways by cobalt precipitation.

The cobalt sulphide precipitation technique, in conjunction with Timm's intensification procedure, was used to delineate the afferent and efferent intramedullary pathways of the seventh cranial nerve complex in the rat. The branchial motor nucleus with the accompanying first part, genu, and second part of the root are described. The motor branches to the superficial facial musculature do not contain fibres of geniculate ganglion origin or fibres which terminate in the spinal trigeminal nucleus. The motor branches to the deep facial muscles arise from the dorsal part of the branchial motor nucleus and traverse to the midline medial to the genu, then project under the genu into the lateral reticular formation before exiting with the facial nerve. The salivatory and lacrimal nuclei and their intramedullary pathways are described. Sensory fibres from the cutaneous auricular branch enter the spinal trigeminal tract and most of the chorda tympani gustatory fibres enter the fasciculus solitarius. A smaller number of gustatory fibres extend medially to the region of the salivatory nucleus. Fibres of greater superficial petrosal origin also enter the fasciculus solitarius as well as the medial reticular formation. These findings are discussed in relation to previous anatomical, physiological and clinical reports.

Animals↗