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Biomedical subjects

J Causse

Publications and source records attributed to J Causse.

At least 19 recordsLinked to original sources
PubMed2006

Micellar solubilization of tributylphosphate in aqueous solutions of Pluronic block copolymers. Part I. Effect of the copolymer structure and temperature on the phase behavior.

Solubilization of tributylphosphate (TBP), a polar oil, in various micellar solutions of Pluronic has been investigated by turbidimetry emphasizing the effect of temperature and the role of the PPO and PEO blocks on the phase behavior of the three components systems (Pluronic-TBP-water). [Temperature-composition] diagrams allow monophasic and diphasic domains to be delimited. Two temperatures are shown to have a determining effect on the phase behavior (TBP solubilization); the well known cloud point temperature (CPT, here defined for the three components system) and the solubilization minimum temperature (SMT) which is defined as the lowest temperature allowing solubilization of TBP in the system. Both temperature depend on the copolymer structure and, interestingly, are directly related to the TBP concentration in the medium. Monophasic microemulsions are observed when the temperature ranges between the SMT and the CPT. When T CPT the system separates in two phase due to the co-precipitation of TBP and Pluronic. Moreover an unexpected evolution of the CPT with the TBP content clearly indicates the occurrence of a structural change of the microemulsions which allows higher quantities of TBP to be solubilized. But the structural change does not allow alone higher quantities of TBP to be solubilized. A well compromise between the SMT and the CPT must be also observed so as to obtain a large extent of monophasic domain after the restructuration. The best compromise is obtained with Pluronics with intermediate hydrophobic character. Reversely, hydrophobic and hydrophilic Pluronics exhibit a very small extent of monophasic domain after the restructuration which does not allow benefit by the structural change.

Journal Article↗
PubMed2006

Micellar solubilization of tributylphosphate in aqueous solutions of Pluronic block copolymers. Part II. Structural characterization inferred by 1H NMR.

The solubilization of tributylphosphate (TBP), a polar oil, in various micellar solutions of Pluronic has been investigated by (1)H NMR spectroscopy. Partial phase diagrams of the three components systems (Pluronic-TBP-water) have shown two characteristic temperatures, called CPT and SMT, which control the phase behavior (see Part I); Both temperature depend on the copolymer structure and, interestingly, are directly related to the TBP concentration in the medium. Monophasic microemulsions are observed only when the temperature ranges between the SMT and the CPT. Moreover, the evolution of the CPT with the TBP content clearly indicated the occurrence of a structural change of the microemulsions which allows higher quantities of TBP to be solubilized. In this second part, (1)H NMR studies of TPB/micellar systems have essentially focused on elucidating the nature of the interactions between TBP and micelle, or on the location of the solubilized species, mainly from the dependence of chemical shifts or linewidths on TBP concentration. Especially, the NMR spectra of the microemulsions before and after the structural change have been compared with those obtained for pure solution of Pluronic in D(2)O at different temperatures and in CDCl(3). The analysis of the (1)H NMR chemical shifts suggests a structural transformation of the TBP-Pluronic micelles in the sense of an hydrophobic TBP-PPO core becoming more and more dense as the TBP concentration increases. Especially, (1)H NMR data evidence an evolution of the hydration state of the hydrophobic core following addition of TBP in the micellar solutions. During the addition of TBP, the microemulsion structure turns from spherical swelled micelles to nanodroplets of pure TBP stabilized by the Pluronic (pure nanophase of TBP stabilized by the copolymer). It is shown that the structural change strongly depends on the temperatures (CPT and SMT, see Part I) and on the copolymer structure.

Journal Article↗
PubMed1982

[Antibacterial therapy in surgery of the inner and middle ear. A study of co-trimoxazole penetration into the perilymph (author's transl)].

Studies of the type presented here have rarely been undertaken and should be useful in surgery and pathology of the inner and middle ear. Samples of perilymph were collected during stapedectomy in patients with otosclerosis. In view of the very small volume of perilymph obtainable from each patient's vestibule (2 to 4 microliter), the only assay method that could be used to measure drug levels was thin layer chromatography on silica gel. Despite pooling of the perilymphs of 5 patients, trimethoprim (TMP) levels could not be measured but the authors were able to demonstrate that sulfamethoxazole (SMZ) does penetrate into the perilymph. Since the TMP-SMZ combination (co-trimoxazole) is active against the pathogens usually encountered in middle ear fluids, it is concluded that the drug could be of benefit in the treatment of middle and inner ear infections or after surgical operations on this area.

Adult↗
PubMed1982

Bone resorption in otospongiosis.

"Considerable interest has been raised in recent years concerning the basic mechanisms involved in bone destruction and rebuilding in the otospongiotic focus. Under general bone resorption the osteoclasts play a decisive role, but in otospongiotic tissue electron-microscopic and cytochemical studies have shown that osteoclasts alone are not responsible for the bone resorption. Mononuclear histiocytes found in the marrow spaces and in the surrounding bone of an otospongiotic focus together with osteocytes take active part in the resorption. Cytochemical studies of acid phosphatase activity have shown that hydrolases in the lysosomes are expelled into the surrounding tissue, resulting in its resorption.

Acid Phosphatase↗
PubMed1981

Surgeon's workshop: Eighteen-year report on stapedectomy. IV. Long-term functional results.

This is the last of a series of 4 articles detailing the history of 20893 stapedectomies over an 18-year period. In this fourth part, the authors study long-term functional results in relation to the type of stapedectomy, the importance of the cochlear involvement and the general pathology, mainly vascular. The come to the conclusion that good long-term functional results imply the necessity of combining a carefully performed stapedectomy using a living tissue graft, a strict audiometric surveillance and an adequate postoperative therapy, including (if necessary) an extensive fluoride therapy.

Cardiovascular Diseases↗
PubMed1980

Eighteen-year report on stapedectomy. II. Postoperative therapy.

This second section deals with the basis of postoperative therapy following stapedectomy. They develop first the immediate postoperative care, then maintenance therapy, mainly NaF therapy to slow down or arrest cochlear enymatic deterioration, if needed.

Adult↗
PubMed1980

Eighteen-year report on stapedectomy. I. Problems of stapedial fixation.

This first section deals with various techniques performed by the authors who conclude in favour of a living tissue graft sealing the oval window, particularly Teflon-piston against veingraft, i.e the "Teflon-interposition' technique. Intra-operative problems of associated diseases and of the technical difficulties encountered during stapedectomy, are related and their treatment explained. Revision operations and immediate postoperative therapy end this first part.

Anesthesia↗
PubMed1979

A new nystagmographic test for the elicitation of sub-clinical vertebro-basilar insufficiency and poor cochleo-vestibular vascularization.

The nystagmus due to vertebro-basilar artery insufficiency is that nystagmus which is induced by torsion and extension of the neck, continued for more than 3 minutes, after nystagmus of other types has been excluded. It is of vascular origin, in contra-distinction to nystagmus of cervical origin, which is proprioceptive. It permits the detection of sub-clinical vertebro-basilar insufficiency, and it should be elicited before any operation which requires prolonged cervical rotation. It is a very simple method which can be performed at the end of the classical torsion swing test, and we have found the results very informative.

Cochlea↗
PubMed1978

[Vertebral-basilar artery insufficiency nystagmus (author's transl)].

The vertebral-basilar artery insufficiency nystagmus is the nystagmus induced by torsion and extension of the neck, continued for more than three minutes, after nystagmus of other origin has been excluded. It stands particularly in opposition with the nystagmus of cervical origin, which is proprioceptive. On the contrary, vertebral-basilar artery insufficiency nystagmus is of vascular origin. It enables the detection of an infra-clinical vertebral-basilar insufficiency. It deserves to be elicited before subjecting patients to any operation requiring prolonged cervical rotation.

Basilar Artery↗