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Biomedical subjects

P David

Publications and source records attributed to P David.

At least 217 records · Page 12Linked to original sources
PubMed1979

[Development of bacterial populations of telluric, enteric, and marine origin in planktonic systems exposed to urban pollution; mathematical data analysis].

A study of the comparative distribution of different types of bacterial populations in the sea area where the city of Marseille rejects its waste water shows that, when in contact with the marine environment, a great part of the allochthonic bacterial population undergoes physiological stress expressed by an abrupt reduction of the effectives and by weak values of the energetic charge. The presence of coliforms and streptococci in waste water lens, at important distances from discharging conduits, shows the possibility of a large diffusion for a fraction of the bacterial populations that withstand the initial stress. From mathematical analyses, an inverse correlation is revealed between detergents and the bacterial population as a whole, and between phenols and various allochthonic bacterial populations. The above results were evidenced through a sampling strategy based upon a 24-h-cycle study and a search for mathematical correlations between several biological, chemical, and physical parameters.

Adenosine Triphosphate↗
PubMed1979

Somatosensory evoked potentials (S.E.P.) in slow pathological compression of the spinal cord.

Somatosensory evoked potentials (S.E.P.) were used to examine twelve patients who had slow compressive lesions of the spinal cord (ten cases of spondylotic myelopathy, one neurinoma, one metastasis of a vertebral body). 73 per cent of the recordings were found to be abnormally reduced in amplitude, and/or showed prolonged latency times aa regards the primary and secondary complex. Patients with a clinical lesion of the dorsal column showed a clear reduction in amplitude in the recordings (sometimes coupled with slowed latency), especially in the primary complex. Patients with symptoms indicative of an injury to the ventrolateral region of the spinal cord showed tracings with alterations most of all related to the secondary complex. In 76 per cent of cases, the somatosensory evoked potentials were in accordance with the level of the compression, the degree of invalidity, and the clinical picture.

Adult↗
PubMed1978

[The formation of tooth germs in teratomas].

The teeth buds which are observed in some teratomas ought to provide a useful system for the study of the development of organ structures in these tumours. They exhibit well defined characteristics in space and time. In contrast with normal development tooth bud formation in teratomas display malformations and other observable characteristics which are primarily the consequence of defects in coordination of activities among cells. Cyto-differentiation appears to be normal and the defective organogenesis must represent a breakdown of the principles which underlie the organization of structures. The possible role of the environment in organizing structure is discussed. Teratomas are unique biological systems which display in a dynamic way a panoply of teratological developmental processes of which teeth buds represent a fragmentary, repetitive and conspicuous expression.

Cell Differentiation↗
PubMed1977

[Odontogenesis, organogenetic model in teratomas: crown formation].

Using the technique of 3 dimensional reconstruction, the various steps involved in the formation and growth of the crown of a tooth primordium observed in a complex ovarian teratoma have been compared with that occurring in dermoid cysts and in the normal dental system. Inside dermoid cysts, the characteristic form of the tooth is established during the production of the dentine and enamel and the process is often similar to that occurring during normal tooth development. In teratomas, however, organogenesis and morphogenesis take place within a system undergoing multidirectional development. They are dissociated during both the embryonic stage and that of a structural formation. Morphogenesis is the most disturbed and the role of the environment is presumably therefore very important.

Dermoid Cyst↗
PubMed1975

[Ophthalmoplegia in dermatomyositis].

A case in which apparently myasthenic ophthalmoplegia had been observed more than six years prior to the onset of dermatomyositis is reported. The clinical picture is described and the possibility of a partially common pathogenesis for both forms is mooted. It is suggested that initial local disturbance of neuromuscular transmission was eventually followed by "aggression" against the muscle fibres.

Dermatomyositis↗
PubMed1975

[Real time processing of data from a clinical biochemistry laboratory by means of a computer system].

Our experience on the use, for several years, of an off line data processing system, has permitted the development of a more advanced system. The basis of the new system is implantation in the laboratory of a minicomputer, linked secondarily to a large computer. The introduction of viewing apparatus favours the development of conversational procedures essential for this application. The organisation of work stands, which varies with the type of blood investigation carried out, whether automatic, semi-automatic or manual, and depends on the use of specialised terminal, e.g. key-board, screen or printing machine, was particularly studied. Simpler procedures were also fully studied, for a routine laboratory must continue to function if the computer breaks down.

Clinical Laboratory Techniques↗