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Biomedical subjects

G Martin

Publications and source records attributed to G Martin.

At least 379 records · Page 21Linked to original sources
PubMed1983

Ultrastructure of the sinus gland and lateral cephalic nerve plexus in the isopod Ligia oceanica (Crustacea Oniscoidea).

Isopod crustaceans have two distinct cephalic neurohemal organs: the sinus gland (SG) and lateral cephalic nerve plexus (LCNP). The present study of Ligia oceanica was designed to ascertain the ultrastructure, during the moulting cycle, of the terminals constituting the SG and LCNP, both of which store and release neurosecretory material, and to trace these terminals to their probable origin in neurosecretory perikarya. The SG was observed to contain four types of terminals (I, II, III, and IV) assigned, on the basis of the appearance of their neurosecretory granules, to four types of neurosecretory cells in the protocerebrum (beta 1, beta 2, B1, and Bu). When the same morphological criteria were applied to the LCNP, two types of terminals were found--III' and IV'. Type III' was thought to originate in the Bp plexus cells and in the B2 cells of the suboesophageal ganglion. The origins of Type IV' terminals were believed to be the Bu and Bm cells of this ganglion. Release from both the GS and LCNP occurred by exocytosis. The discussion attempts to relate the ultrastructural variations observed in the SG and LCNP with existing data on the neuroendocrine regulation of the moult. Such regulation involves the two antagonistic hormones (moult-inhibiting and moult-accelerating) which determine the circulating ecdysteroid level. It is also suggested that the plexus cells are the site of synthesis of a factor controlling the release of the exuviation factor.

Animals↗
PubMed1983

[Neuroblastoma of the olfactory nerve].

The histopathology of neuroblastomas of the olfactory nerve, especially the difficult differential diagnosis is described by means of our own observations, and compared with other less differentiated malignant tumours of the inner nose. Ultrastructural results are presented, histogenesis and classification of olfactory neuroblastomas in neuroepithelioma, neurocytoma and neuroblastoma are discussed. The literature is reviewed, whereby clinical symptoms, therapy and prognosis of these tumours are described.

Adolescent↗
PubMed1983

[Automatic reading of microtitration plates: identification of Enterobacteriaceae and determination of their minimal inhibitory concentrations].

The authors evaluate an automatic microplate reader (Auto Reader Dynatech) and its application software. 291 strains of Enterobacteria belonging to 28 species were identified and 1,856 MIC were determined. The identifications made with the MIC 2000 tube were correct in terms of genus and species in 270 strains (92.8%) and in terms of genus in 274 strains (94.1%). The automated determination of the MIC was in complete agreement with visual reading in 90.6% of cases and with a deviation of +/- 1 dilution in 99.6% of cases. The programme was improved by the authors. This system is a new approach to automatization in microbiology.

Enterobacteriaceae↗
PubMed1983

Relationships among human amniotic fluid dipalmitoyl lecithin, postpartum respiratory compliance, and neonatal respiratory distress syndrome.

The major molecular species of amniotic fluid phosphatidylcholine were determined as diacylglycerol trimethylsilyl ether derivatives by gas-liquid chromatography with use of glass capillary columns. We studied amniotic fluid specimens from 48 pregnancies. As expected, the major disaturated species of amniotic fluid phosphatidylcholine, dipalmitoylphosphatidylcholine, and palmitoylmyristoylphosphatidylcholine increased with gestational age, whereas phosphatidylcholine species with 34, 36, and 38 carbon atoms in the acyl radicals decreased. Although the amniotic fluid samples were obtained shortly before parturition (4.2 +/- 3.7 h, mean +/- SD), the correlation between dipalmitoylphosphatidylcholine concentration in amniotic fluid and gestational age was better than between dipalmitoylphosphatidylcholine concentration and the compliance of the respiratory system of the newborns. In addition, the percentage of amniotic fluid phosphatidylcholine species present as dipalmitoylphosphatidylcholine seemed to be a more reliable predictor of lung maturity than was the absolute dipalmitoylphosphatidylcholine concentration in amniotic fluid.

Amniotic Fluid↗
PubMed1982

Activity-induced potassium accumulation and its uptake in frog ventricular muscle.

1. Extracellular K+ activity in frog ventricular muscle was monitored with a K+-selective micro-electrode during and following periods of rapid stimulation. 2. During activity K+ accumulated in the paracellular space, declined with continued beating and became depleted below bathing K+ concentrations, [K+], when activity was terminated. 3. The re-uptake and depletion of K+ was inhibited by ouabain, Li+ and lowering bathing [K+], and was enhanced by prolonged stimulation, raising bathing [K+], and by addition of adrenaline. These ionic and drug dependencies of the K+ re-uptake process are similar to the ionic and drug dependencies of the Na+-K+-ATPase system. 4. Frequency-induced K+ accumulation appears to result from a delay in the activation of the Na+ pump. 5. Possible changes in intracellular sodium concentration, [Na+]i, in the response to changes in frequency, appear to be a more powerful stimulant of the K+ re-uptake process than changes in extracellular potassium concentration, [K+]o. 6. Frequency-induced changes in [K+]o were also detected by measurements of resting potential. Alterations in membrane potential and action potential duration observed during and following electrical stimulation are suggestive of an electrogenic K+ re-uptake process. 7. Aside from their direct effects on the action potential, Ca2+ and Mg2+ had little or no effect on Na+ pump activity. While Ni2+ suppressed pump activity, Ba2+ indirectly enhanced the K+ uptake process by blocking the resting K+ conductance. 8. K+ uptake rate was estimated to range between 3 and 8 p-mole/cm2.sec. Since diffusion in and out of the paracellular space was a much slower process (t1/2 60-90 sec), it contributes little to the beat-to-beat control of paracellular [K+].

Animals↗
PubMed1982

[Neuroendocrine control of reproduction in Crustacea].

The neuroendocrine factors synthetized by various regions of the nervous system and which have inhibiting or stimulating effects can control the male and female physiology of malacostraca via sexual hormones and moulting hormone. There are between decapods and peracarids functional homologies but some differences can be noticed as to the localization of these antagonistic neurosecretory systems. The functioning of these systems is regulated by external factors such as the photoperiod and the temperature. The interactions between these different neurohormones, the sexual hormones and the moulting hormone are discussed.

Animals↗
PubMed1982

[Ultrastructural study of sinus gland regeneration in the oniscoid Porcellio dilatatus Brandt, further data on the origin of this neurohemal organ].

In this paper we analyse the consequences of cutting off axonal track connecting the neurohemal organ (sinus gland) to the pericarya of the protocerebron median part (cortical zones I' and V' - Fig. 1). After cutting the optic lobe, at the medulla interna level (cortex IV' - Fig. 1) a functional neo-sinus gland with 3 types of endings and glial cells is form again. We experimentally investigate the limits of the regeneration area of the sinus gland. Investigation of atypical but functional sinus gland (Fig. 4) allowed us, on one hand, to specify these limits and on the other hand to relate the endings of type III to a cellular type missing in the protocerebron central part. The dynamic study of the setting up of a neo-sinus gland is a quick phenomenon: exocytosis can be seen 24 to 48 h after cutting the optic lobe (Fig. 7). The optic lobe cutting off induces ephemeral modifications, on the one hand, at the level of the beta 1, neurosecretory cells: decrease of golgi activities, crinophagy, presence of crystalline-like structures; on the other hand, at the level of the nearby glial cells which show a lot of dense bodies (Fig. 9, 12).

Animals↗
PubMed1981

Neurogenic sarcomas of the neck in neurofibromatosis.

Based on two observations and a review of the literature, the pathological and clinical findings in sarcomas of the neck in patients with neurofibromatosis are described. Histologically these neurogenic tumours show a manifold picture; in addition to spindle-cell sarcomas pleomorphic structures are to be found, which can be similar to rhabdomyo-, lipo-, chondro-, angio-, or osteogenic sarcomas so that a histological diagnosis of a neurogenic sarcoma cannot always be made without clinical details. Up to the present surgical treatment is preferred; the value of cytostatic therapy and irradiation is controversial. The results of treating these tumours are unsatisfactory. Of 29 cases reported in the literature, only two could be found in which the patient survived without a recurrence for more than five years.

Adolescent↗
PubMed1981

The management of pain following laminectomy for lumbar disc lesions.

Assessment of the results of laminectomy for lumbar disc lesions is unsatisfactory, but it seems that some degree of recurrent pain is virtually inevitable. The clinical features and incidence of the various painful syndromes seen in these patients, including one, the sacro-spinalis insertion syndrome, which has not previously been described, are outlined and the management of each is discussed with reference to two personal series, one of 98 patients consecutively undergoing laminectomy and the other of 35 patients referred because of recurrent pain following laminectomy. Finally, problems of prophylaxis are considered.

Back Pain↗