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Biomedical subjects

C Laurent

Publications and source records attributed to C Laurent.

At least 145 records · Page 8Linked to original sources
PubMed1993

Immortalization of human cervical keratinocytes by human papillomavirus type 33.

Ten immortalized cell lines were established by transfection of human cervical keratinocytes (CK) with HPV-33 DNA and some of their characteristics were investigated. The following observations were made: (a) several cell lines have reached over 100 population doublings in vitro; (b) 3 transcripts were observed, 2 being encoded by the E6/E7 open reading frames (ORFs); (c) cytogenetic analyses showed important genetic modifications such as aneuploidy and isochromosome formation of the q arm of chromosome 8; (d) 2 of the 10 cell lines developed colonies in soft agar but none was able to form tumors when injected s.c. into nude mice; (e) Southern analysis suggested that a single copy of HPV-33 is integrated at a single common site within the genome of the 10 cell lines. These immortalized cell lines should be useful for studying mechanisms involved in proliferation, differentiation and neoplastic transformation of CK by HPV-33.

Animals↗
PubMed1993

Cytogenetic monitoring of a village population potentially exposed to a low level of environmental pollutants. Phase 1:SCE analysis.

By analogy to the techniques applied for monitoring biological effects of exposure to genotoxic agents in occupational populations, we have carried out cytogenetic monitoring in a group of inhabitants of a village (Mellery, Belgium) suspected to have been exposed to a variety of toxic environmental pollutants. These pollutants probably originated from a neighboring chemical wastes site. A group of 51 environmentally exposed and 52 reference persons (including children) were examined for the frequency of sister-chromatid exchanges (SCE) in their peripheral blood lymphocytes. The technique was further refined by using a high frequency cells (HFC) analysis. Analysis of the reference subgroups showed a significant difference between non-smoking adults and children. The influence of tobacco was clear, too. In the exposed group, no significant differences could be demonstrated between either the smokers or the non-smokers or the children. Furthermore, not only were the mean frequencies of SCE higher than in the respective reference subgroups but comparison between the two groups also showed a higher number of individuals presenting a HFC level above the background in the exposed group. Surprisingly, the difference was more pronounced for the children. A follow-up of the same exposed population carried out 18 months later and after remediation of the atmospheric chemical release, the previously observed tendencies in the exposure parameter remained unmodified.

Adult↗
PubMed1993

[Neisseria mucosa endocarditis complicated by intracerebral aneurysm].

BACKGROUND: Serious complications, such as emboli and mycotic aneurysms, are still frequent in documented cases of infective endocarditis. Infecting organisms other than Streptococcus viridans and Staphylococcus are becoming more common. CASE REPORT: A 8 year-old girl was admitted because of a sudden pain in the right calf followed by complete disability. She had low-grade fever and presented with a moderate heart murmur with no sign of congestive heart failure, a severe pain at palpation of her calf with no Homans sign; she had many dental caries. Laboratory data indicated leukocytosis with increased percentage of polymorphonuclear cells and increased sedimentation rate. Ultrasonography of the calf showed laceration of the muscle with blood suffusion. Echocardiography showed vegetations involving the mitral valve. Intravenous antibiotic therapy with penicillin G and netilmicin was instituted, but mitral insufficiency appeared 7 days later while the fever persisted. At that time, the brain CT scan showed ischemic lesions, while angiography showed several mycotic aneurysms. Neisseria mucosa was recovered from the 5 initial blood cultures 16 days after the onset, and penicillin G was replaced by ampicillin. A second vegetation involving the aortic valve was seen a few days later, and a recent arterial embolism to the right leg was suspected because fever and pain reappeared. The brain ischemic lesions gradually disappeared and a second angiography performed 3 months after the first showed that all but one large mycotic aneurysm had disappeared; this last aneurysm was excised. Four years later, the child is in good health without any neurological sequelae but having mitral insufficiency. CONCLUSION: This girl presented with classical complication of infective endocarditis due to Neisseria mucosa, a saprophytic organism of the oral cavity. This is the second report of such an infection in children.

Ampicillin↗
PubMed1993

Influence of blood storage after in vitro exposure on the yield of micronuclei observed in human lymphocytes.

In a cooperative study, four laboratories evaluated the micronucleus test in irradiated and non-irradiated lymphocytes with respect to time of storage, the difference between X-ray and gamma exposure and inter-observer variance. The results were compared with parallel studies on dicentric aberrations. No significant differences between laboratories, with respect to storage time or between gamma and X-irradiation were observed for micronuclei and dicentrics using analysis of variance. However, micronuclei are not suitable for an assessment of exposure inhomogeneity because of a significant overdispersion already in controls and homogeneously irradiated samples.

Belgium↗
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↗