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Biomedical subjects

M R Martin

Publications and source records attributed to M R Martin.

53 records · Page 3Linked to original sources
PubMed1977

The identification of mossy fibres and their cells of origin in the normal and Lurcher mutant mouse.

The behavioural mutant mouse Lurcher survives to adult life as the heterozygote (Lc/+) and shows a disorder of gait. The neurological lesion has been shown to involve degeneration of Purkinje cells and inferior olivary neurones (Caddy and Biscoe 1976). It follows that the climbing fibre input is reduced and we wished to know if the mossy fibre input was also affected. Heterozygote Lurcher mutants were compared with the wild type in all experiments. Mossy fibre glomeruli were identified in the cerebellum of the mutant mouse by electron microscopy. Horseradish peroxidase (HRP) was injected into the cerebellum and was found in the cells of Clarke's column in the spinal cord. Electrophysiological experiments showed that following stimulation of the sciatic nerve evoked responses could be recorded in the cerebellum. It is concluded that the mossy fibre input to the cerebellum is intact in the Lurcher mutant mouse.

Animals↗
PubMed1977

Physiological studies on facial reflexes in the rat.

Experiments were performed on 36 male albino rats anaesthetized with pentobarbitone sodium and paralyzed with gallamine triethiodide. Recordings were made with single and multibarrel glass microelectrodes in the facial nucleus and monopolar silver wire electrodes on the lingual, facial, glossopharyngeal and hypoglossal nerves. The absolute refractory period for facial motoneurones is 2-3 ms, the relative refractory period has a duration of 26-34 ms and the range in axonal conduction velocities is from 15 to 45 m.sec-1. No evidence for afferent fibres in the muscle branches of the facial and hypoglassal nerves could be found. The lingual and glossopharyngeal nerves show reflex connexions with both the facial and hypoglassal nerves. The time courses of the potentiations and depressions of test facial antidromic field potentials following lingual and glossopharyngeal conditioning stimuli are given. Evoked synaptic activity and the distribution of field potentials in the facial mucleus following lingual and glossopharyngeal nerve stimulation are also described. The observed lingual and glossopharyngeal-facial reflexes are discussed with respect to blink reflexes.

Action Potentials↗
PubMed1977

So-called pseudosarcoma of the esophagus: nodal metastases of the spindle cell element.

A polypoid lesion of the esophagus with all the morphological features of a so-called pseudosarcoma produced nodal metastases of the spindle cell element. Ultrastructurally, these spindle cells showed only fibroblastic features. The findings in this case and a review of cases reported as pseudosarcoma of the esophagus lend little support for the contention that they differ from cases categorized as carcinosarcoma of the esophagus.

Aged↗
PubMed1977

Numbers and diameters of motoneurons and myelinated axons in the facial nucleus and nerve of the albino rat.

The number and diameter of the motoneurons in serial sections of the facial nucleus in the albino rat were estimated using a photograph-camera lucida technique for counting and measuring cells in conjunction with a systematic section method for sampling the population. The mean diameter of facial motoneuron nucleoli was also estimated. Total cell counts were estimated using two formulas, one a basic count and the other the basic count corrected for split nucleoli errors. The mean motoneuron diameter is 33-93 micronm (+/- 6-18 micronm S.D.). The number and diameter of myelinated axons in both the facial nerve and its cutaneous auricular branch at the level of the stylomastoid foramen were estimated. There are 5353 myelinated axons in the facial nerve, with a mean diameter of 2-74 micronm, and 627 myelinated axons in the cutaneous auricular branch with a mean diameter of 1-47 micronm. The accuracy and reproductibility of results using the photograph-camera lucida technique for counting and measuring cells and the systematic section method of sampling are compared with those of the methods used by previous investigators. The accuracy of results obtained for estimates of the total cell count using the formulas for the basic count and the basic count corrected for split nucleoli are also compared.

Animals↗
PubMed1976

The sensitivity of rat spinal interneurones and renshaw cells to L-glutamate and L-aspartate.

L-Glutamate and L-aspartate were administered electrophoretically near spinal interneurones and Renshaw cells of pentobarbitone-annaesthetized rats. Other spinal interneurones were consistently more sensitive to L-glutamate than to L-aspartate. Renshaw cells, however, showed no consistent difference in their sensitivity to these two amino acids. The results, which are compared with those reported previously in the cat, support the hypothesis that L-glutamate could be a transmitter at spinal primary afferent terminals.

Action Potentials↗
PubMed1976

Incidence of renomedullary interstitial cell tumours and correlation with hypertension.

In a study of 223 consecutive autopsies of subjects older tumours were found in 36 cases (16%) (25/130 males and 11/93 females). Only eight kidneys showed multiple lesions. Renomedullary interstitial cell tumours were correlated with the presence or absence of hypertension and no statistically significant correlation could be demonstrated. The incidence of renomedullary interstitial cell tumours increases with age.

Adolescent↗
PubMed1976

Structure-activity relations of excitatory amino acids on frog and rat spinal neurones.

1 A series of compounds structurally related to glutamic acid has been tested on frog and rat spinal neurones. The substances were added to procaine-containing medium bathing the isolated hemiscected spinal cord of the frog, and their potencies in depolarizing motoneurones were assessed by the magnitude of the potential produced in the ventral root. The electrophoretic technique was used to administer the substances around single interneurones of the rat spinal cord and the relative potencies of the compounds as excitants assessed by the magnitude of the currents required to produce similar rates of neuronal firing. 2 Parallel structure-activity relations were observed in the two series of experiments, suggesting that the receptors for excitatory amino acids on frog and rat spinal neurones are similar. 3 Quisqualate, domoate and kainate were the strongest excitants in both animals, with potencies around two orders of magnitude higher than that of L-glutamate. 4 2,4,5-Trihydroxyphenylalanine (6-OH-DOPA) was a stronger excitant and L-3,4-dihydroxyphenylalanine (L-dopa) a weaker excotamt than L-glutamate on frog spinal motoneurones. The former compounds was also a more potent convulsant than L-glutamate on intraventricular injection into mouse brain. The lack of activity of 6-OH-DOPA on electrophoretic administration was attributed to oxidation. 5 Unlike the majority of amino acid excitants, several of the compounds shown in the present work to have moderate excitatory activity are not anionic at physiological pH. This indicates either that two negatively charged groups are not essential for interaction with a common excitatory receptor, or that more than one type of receptor is involved in the actions demonstrated.

Amino Acids↗
PubMed1975

Neglected coeliac disease.

A review has been carried out of patients diagnosed as having coeliac disease some years previously and subsequently lost to follow-up. Most were unaware of the need for continuing treatment and had returned to a normal diet. The resulting morbidity was slight, although one patient had died of a small-bowel lymphoma. If untreated coeliac disease is indeed a pre-malignant condition, then it is suggested that there must be a large population at risk, with no motivation to return to treatment other than the risk of malignancy itself.

Adolescent↗
PubMedDate not supplied

Electrophysiological observations on the spinal cord of the normal and dystrophic mouse.

A method of carrying out electrophysiological experiments on the mouse spinal cord is described. The conduction velocity in the spinal dorsal roots (DR) of the normal mouse was in the range 10-100 m sec-1 and in the ventral roots (VR) 50-70 m sec-1. In the dystrophic mutant (129 ReJ dy/dy) the conduction velocity for both roots was usually in the range 0.1-2.0 m sec-1. Reflexes from DR to VR were recorded in both mutant and wild type animals and it was concluded that the delays in the mutant reflex were probably due to the slower conduction velocity in the roots. Postsynaptic inhibition and presynaptic inhibition were demonstrated and records were made from Renshaw cells and intracellularly from motoneurones. Delayed activity in spinal reflex paths, probably of supraspinal origin, was more pronounced in the dystrophic mutant. It is concluded that if the dystrophic mouse mutant were to be regarded as a model for human disease then similar reflex delays should be demonstrated in human subjects with muscular dystrophy.

Afferent Pathways↗