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Biomedical subjects

C Laurent

Publications and source records attributed to C Laurent.

At least 19 recordsLinked to original sources
PubMed1992

[A case report of Russel's diencephalic cachexia].

The case of an infant admitted for evaluation of severe emaciation with intermittent ocular anomalies including strabismus and nystagmus is reported. This case demonstrates the value of magnetic resonance imaging and transfontanellar ultrasonography for the diagnosis of diencephalic syndrome of infancy. The prognosis of this condition is usually grim, in particular because of the severe emaciation which is disproportionate with the tumour spread. Pathophysiologic hypotheses put forward to explain this cachexia are reviewed. Although cytokines such as TNF alpha are currently incriminated in the pathophysiology of cachexia induced by a number of conditions, they have not yet been studied in diencephalic syndrome of infancy. TNF alpha is a potent lipolytic agent. Excessive production of TNF alpha may be involved in the genesis of the emaciation characteristic of diencephalic syndrome. Inappropriate production of TNF alpha may respond to the administration of specific anti-TNF monoclonal antibodies. This approach may be considered as a means for treating emaciation in patients with diencephalic syndrome of infancy.

Astrocytoma↗
PubMed1992

Cochlear effects of hyaluronan applied on ruptured round window membrane.

The purpose of the present experimental study was to determine whether hyaluronan (hyaluronic acid, HYA) exerts any functional or morphologic ototoxic effects on the cochlea when in contact with a ruptured round window membrane (RWM). HYA in 1% solution was applied in the round window (RW) niche of rats (n = 6) prior to perforating the RWM. In a control group (n = 6) the RWM was perforated alone. Cochlear functioning and structure were monitored by recording auditory brainstem responses (ABRs) at 2-31.5 kHz and by scanning electron microscopy. Perforation of the RWM alone resulted in immediate loss of ABR thresholds between 6 and 31.5 kHz in 2 of 6 animals. Similar results were obtained after application of HYA into the RW niche and subsequent RWM perforation. In both treatment groups the mean ABR thresholds and mean latencies for wave II at the ABR threshold returned to the pre-surgical (normal) range after 2 months. Also with respect to the cochlear morphology the results in both treatment groups were alike including minor structural changes in hair cell stereociliae but no loss of hair cells. It is concluded that HYA, when instilled into the middle ear with the inner ear opened, is free from cochlear ototoxic effects. Our present findings enhance the potential usefulness of HYA in otosurgery, even in cases when the inner ear has been opened and/or when one wishes to protect the inner ear.

Animals↗
PubMed1991

Localization of hyaluronan in various muscular tissues. A morphological study in the rat.

The histochemical distribution of hyaluronan (hyaluronic acid, HYA) was analysed in various types of muscles in the rat by use of a hyaluronan-binding protein (HABP) and the avidin-biotin/peroxidase complex staining procedure. Microwave-aided fixation was used to retain the extracellular location of the glycosaminoglycan. In skeletal muscles, HYA was detected in the connective tissue sheath surrounding the muscles (epimysium), in the septa subdividing the muscle fibre bundles (perimysium) and in the connective tissue surrounding each muscle fibre (endomysium). HYA was heterogeneously distributed in all striated muscles. In skeletal muscles with small fibre dimensions (e.g., the lateral rectus muscle of the eye and the middle ear muscles), HYA was predominantly accumulated around the individual muscle fibres. Perivascular and perineural connective tissue formations were distinctly HYA-positive. In cardiac muscles, HYA was randomly distributed around the branching and interconnecting muscle fibres. In comparison, smooth muscle tissue was devoid of HYA.

Animals↗
PubMed1991

Hyaluronan in human skeletal muscle of lower extremity: concentration, distribution, and effect of exercise.

The concentration and localization of hyaluronan (HYA) were determined in biopsy specimens from resting human quadriceps femoris and anterior tibial muscles. The influence of physical exercise on HYA concentrations in the quadriceps femoris muscle and in blood was also evaluated. A sensitive radioassay was used for the quantification of HYA. The distribution of the glycosaminoglycan was demonstrated using a histochemical method that involved microwave-aided fixation and an HYA-binding protein. At rest, the muscle HYA concentration was 34.9 +/- 23.6 (SD) micrograms/g muscle wet wt with a large interindividual variation. Exercise had no significant effect on the muscle HYA concentration. The serum HYA concentration increased from 35.9 +/- 22.7 to 53.4 +/- 57.1 micrograms/l during exercise, but 30 min after the exercise the HYA concentration was significantly lower (19.1 +/- 6.3 micrograms/l) than the initial preexercise value. In resting skeletal muscles of the lower extremity, HYA was heterogeneously distributed in the perimysium and endomysium. Perivascular and perineural connective tissues were distinctly HYA positive.

Adult↗
PubMed1991

Repair of chronic tympanic membrane perforations using applications of hyaluronan or rice paper prostheses.

A controlled randomized study was performed in 60 patients with 64 chronic, dry tympanic membrane (TM) perforations. The perforations were randomly allocated to either resection of the perforation rim and instillation of 1% hyaluronan (Healon; HYA) in the perforation gap once daily for 7 days (33 ears) or resection of the perforation margin and application of a sterile rice paper prosthesis (31 ears). The treatment effect was documented by TM photography and morphometric measurements of the perforation area. The hearing was assessed with puretone and high-frequency audiometry. After 2 months, 5 of the HYA-treated perforations (15%) and 4 of the rice-paper-treated TMs (13%) were healed. After 1 year, 18 perforations (9 in each treatment group) were healed. In neither group were there any persistent adverse effects on hearing. It is noteworthy that 28% (18/64) of the chronic, long-standing TM perforations could be repaired by these technically simple and time-saving methods. Both procedures should be considered as easy first-choice alternatives to myringoplasty in selected cases.

Adolescent↗
PubMed1991

Hyaluronan applied to lesioned round window membrane is free from cochlear ototoxicity.

Hyaluronan (HYA) in 1% solution was instilled into the round window (RW) niche of rats (n = 6) prior to perforating the round window membrane (RWM). Cochlear functioning and structure were then monitored by recording auditory brainstem responses (ABRs) at 2-31.5 kHz and by scanning electron microscopy. Perforation of the RWM alone (n = 6) resulted in immediate loss of ABR thresholds between 6 and 31.5 kHz in 2 of 6 animals. Similar results were obtained after instilling HYA into the RW niche and subsequent RWM perforation (n = 6). After 2 months, ABR thresholds were recorded at all frequencies in the HYA-treated animals, whereas in 2 of the controls no ABR thresholds could be elicited at 20 and 31.5 kHz. However, in both treatment groups the mean ABR thresholds and mean latencies for wave II at the ABR threshold returned to the pre-surgical (normal) range after 2 months. With respect to the cochlear morphology the results in both treatment groups were also alike including minor structural changes in hair cell stereociliae but no loss of hair cells. It is concluded that HYA, when instilled into the middle ear with the inner ear opened, is free from cochlear otoxicity.

Animals↗
PubMed1990

Ultrasonographic assessment of urinary tract lesions due to Schistosoma haematobium in Niger after four consecutive years of treatment with praziquantel.

A comparative study on the extent of urinary tract abnormalities detected by ultrasound was conducted in two villages in an irrigated area of Niger where the pretreatment prevalences were 64.3% and 58.8% respectively. Fewer bladder lesions (20% of abnormalities) and fewer renal lesions (6% of abnormalities) were observed after four consecutive years of follow-up and treatment with praziquantel in the study village as compared to the control village where 54% bladder abnormalities and 36% renal abnormalities were observed. This study suggests that morbidity due to Schistosoma haematobium infection can be reduced by annual treatment over several years in a highly endemic area without other associated interventions.

Cohort Studies↗
PubMed1989

Hyaluronan in experimental serous and purulent otitis media.

The concentration of hyaluronan (hyaluronic acid; sodium hyaluronate; HA), a major component of connective tissue, was analyzed by a specific radioassay in tissue samples from normal rat middle ears and in tissue and effusions from middle ears affected by experimentally induced otitis media. In normal ears the pars flaccida of the tympanic membrane contained a considerably higher concentration of HA (60 to 200 micrograms/g) than the pars tensa and areas of the medial wall (2 to 7 micrograms/g). In purulent otitis media the pars flaccida contained less HA than in normal ears. The HA concentrations were lower in purulent (3 to 40 micrograms/mL) than in serous (20 to 190 micrograms/mL) effusions. The weight average molecular weight of HA in serous fluid was high (greater than 10(6] and comparable to that in lymph. It is inferred from the study that the subepithelial tissue and its matrix components, eg, HA, must be considered when attempting to understand the function of the middle ear normally and in otitis media.

Animals↗
PubMed1988

Hyaluronan improves the healing of experimental tympanic membrane perforations. A comparison of preparations with different rheologic properties.

Preparations of hyaluronan at various concentrations and molecular weights were topically applied to experimental tympanic membrane (TM), perforations in the rat and their ability to improve the healing pattern was elucidated. The perforation occupied the upper posterior quadrant of the TM. Alterations in healing rate and quality of the healed TM were examined by otomicroscopy and in histologic sections. Hyaluronan enhanced the healing rate and resulted in less opacity and structural alteration of the scar area. Closure time for the TM perforation was correlated to the concentration of hyaluronan but not to its molecular weight or viscosity. Improved scar quality was obtained in the presence of hyaluronan irrespective of its rheologic properties. Hyaluronan improved the restoration of the fibrous connective tissue layer. Treatment of TM perforation in man with hyaluronan at high concentrations should be considered as an alternative to myringoplasty.

Administration, Topical↗
PubMed1988

Budesonide nasal spray as prophylactic treatment after polypectomy (a double blind clinical trial).

This double-blind parallel-group study compared the effect of budesonide with placebo, in the prophylaxis of nasal polyp recurrence after evulsion. Seventy-three patients with first time or recurrent polypectomy were enrolled. At revisits 3 and 6 months after evulsion, the budesonide-treated patients had significantly lower polyp scores than the placebo-treated patients. Only patients with recurrent nasal polyposis benefited from the budesonide treatment, whereas no effect was evident in patients with first time evulsion.

Administration, Intranasal↗
PubMed1988

Control of myogenesis in the mouse myogenic C2 cell line by medium composition and by insulin: characterization of permissive and inducible C2 myoblasts.

Using subcloning and manipulations of culture conditions we have isolated from the mouse myogenic cell line C2 a variant cell line that we named inducible. Unlike the progenitor cells that are referred to as permissive, inducible myoblasts differentiate poorly in Dulbecco modified Eagle medium plus fetal calf serum (FCS) and require the presence of insulin at a high concentration (1.6 10(-6) M) or insulin-like growth factor I (IGFI) at a lower concentration (2.5 10(-8) M) to differentiate. Permissive and inducible myoblasts fail to differentiate when grown in MCDB202 medium plus 20% FCS, even after a prolonged arrest in G1 phase. This shows that an arrest in G1 is in itself insufficient to trigger terminal differentiation. Both cell types also exhibit distinct patterns of accumulation of muscle mRNAs corresponding to sarcomeric actins and myosin light chain MLC1A. The possibility that these two cell lines might represent two different stages of the progression of myoblasts toward terminal differentiation is discussed.

Actins↗
PubMed1986

The catabolic fate of hyaluronic acid.

Part of the hyaluronic acid (HA) synthesized in peripheral tissues enters the blood circulation through the lymph. It is rapidly taken up by the endothelial cells in the liver (half-life in blood is 2.5-5.5 minutes) and degraded. Pure primary cultures of liver endothelial cells were obtained by a newly developed technique and used to follow the metabolism of the polysaccharide on the cell surface. At 37 degrees C the HA is effectively endocytosed and degraded to acetate and lactate. A radioassay specific for HA and sensitive in the nanogram range has been developed to follow the concentration of HA in serum. The normal level in man is 10 to 100 micrograms/l. Elevated serum levels of HA are seen in liver cirrhosis, rheumatoid arthritis and scleroderma indicating that both an impaired catabolism in the liver and an increased synthesis in the peripheral tissues can modify the HA level.

Animals↗
PubMed1979

Comparison of the karyotypes of four Cercopithecoidae: Papio papio, P. anubis, Macaca mulatta, and M. fascicularis.

The karyotypes of two species of baboons, Papio papio and P. anubis, and of two species of Macaca, M. mulatta and M. fascicularis, are compared after the use of numerous banding techniques. No difference was detected between the karyotype of the two Papio species. However, a minor change in the T-staining of a short segment, probably heterochromatic, could be detected between the Papio species and M. mulatta. A paracentric inversion exists between these three and M. fascicularis. These karyotypes are briefly compared with those of the Pongidae and man. The value of the karyotypic criteria and of the methods used for taxonomy is discussed.

Animals↗