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Biomedical subjects

M Bonnet

Publications and source records attributed to M Bonnet.

At least 37 records · Page 2Linked to original sources
PubMed1989

Effect of collagen crosslinking on collagen-water interactions (a DSC investigation).

The effect of collagen cross-linking state on the collagen-water interaction was studied, using Differential Scanning Calorimetry (DSC) which allows the determination of unfreezable water, the variation of enthalpy (delta H) and temperatures of denaturation of collagen to gelatin transition. DSC was performed on intramuscular connective tissue purified with trypsin (control C), depolymerized with penicillamin (P), and reduced with borohydride (B); samples were adjusted with different water contents. For the three tissues, unfreezable water (Wu) and denaturation enthalpy change (delta H) increased with increasing moisture level (Wt); whereas, maximum denaturation temperature (phi M) decreased. The ability of this calorimetric method of investigation to characterize the collagen crosslink state is discussed: maximum limit values of delta H and of Wu decreased significantly with increasing collagen cross-linking degree. Minimum Wt necessary to reach the maximum delta H decreased with crosslinking degree. Likewise significantly different limit values of unfreezable water Wu were reached for smaller Wt the greater the crosslinking of collagen. These results show that the less connective tissues were cross-linked, the more they could bind water. They also demonstrated that the water of collagen hydration can be classified into four states, whose limits vary according to the degree of crosslinking.

Animals↗
PubMed1989

Changes in contingent-negative variation and reaction time related to precueing of direction and force of a forearm movement.

Scalp-recorded contingent-negative variation was analyzed in a reaction time paradigm with full, partial, or no prior information regarding two dimensions of a forearm response: direction (flexion/extension) and force level (weak/strong). Visual cues (light-emitting diodes) were used for the warning and response signals. The reaction time was shorter when direction, rather than force, was known in advance. Source derivation techniques revealed that the somatosensory arm area was more 'activated' by direction than force information, whereas the precentral cortex seemed to be more strongly influenced by force information. Partial advance information was sufficient to trigger preparatory activities specific for the revealed dimension of the ensuing movement.

Adult↗
PubMed1989

[Optic nerve pits: clinical and therapeutic review of 21 cases].

A retrospective study of optic nerve pits in patients referred to our clinic during the last 15 years was conducted. The study included 21 eyes in 19 patients. The optic pit was associated with a serous macular detachment (SMD) in 19 eyes (90%). Various treatments of the SMD were used depending on the time period. Systemic corticosteroids were used in five patients. The SMD did not respond to this treatment. Argon laser photocoagulation was applied to the temporal side of the optic disc in five patients. Intravitreal injection of pure gas was used as an adjunct to photocoagulation treatment in eleven eyes. Pure SF 6 was used in 8 eyes, and C 3 F 8 in 3 eyes. The follow-up after treatment was over 6 months in 10 patients who underwent photocoagulation or the combination of photocoagulation and gas injection. The SMD remained unchanged in two eyes which underwent photocoagulation treatment without gas injection. In the group of patients treated by photocoagulation in association with SF 6 injection, the SMD totally reattached in one eye, decreased in 2 eyes and remained unchanged in 2 eyes. Total resorption of subretinal fluid and permanent retinal reattachment occurred in the 3 eyes treated by intravitreal injection of pure C 3 F 8 as an adjunct to photocoagulation treatment. Further clinical investigations on large series of patients are required to determine whether prolonged retinal tamponade by C 3 F 8 gas in association with photocoagulation treatment is a valuable method in the management of SMD complicating optic nerve pits.

Adolescent↗
PubMed1989

[Curietherapy using a ruthenium and iridium disk in the treatment of choroid melanoma].

Following the experience of the German authors, the treatment of choroidal melanoma with ruthenium 106 disk was introduced in Lyon. Between 1983 and 1988, 127 patients were treated. Results are analysed on a group of 84 patients followed 18 months and more. In 72 cases a reduction of thickness was noted. It was complete in 33 cases. Enucleation was performed in 10 patients due to no response or regrowth. In 3 cases the tumor was sterilized. Five patients died of metastases, and 73 are alive, 3 of them with liver metastases. An afterloading iridium template disk was used in 8 patients. 4 of them with a tumor thickness between 6.5 and 8 mm had a good response. Edema of the fovea was observed in 21% of cases, while cataracts were very unusual with Ru 106. An enucleation was performed in 6 patients because of a complication. A useful vision may be preserved in 60% of cases. The scleral tolerance dose is close to 1,500 Gy. These results are in agreement with those of the literature and are considered to be satisfactory for tumors not exceeding 5 to 6 mm in thickness. If the tumor is located close to the fovea or the papilla, and/or if the thickness is 8 mm or more, proton beam could be a good alternative.

Adult↗
PubMed1989

[C3F8 in the treatment of retinal detachment associated with vitreoretinal proliferation].

The perfluoropropane gas was used as an adjunct to vitreoretinal microsurgery in 60 eyes of 60 patients with rhegmatogenous retinal detachment complicated by proliferative vitreoretinopathy. 0.3 ml to 1.8 ml (average 0.9 ml) of pure perfluoropropane gas was used. The surgical procedure included vitrectomy and scleral buckling in all patients. The follow-up after complete gas absorption ranged from 6 months to 3 years in the successful eyes. Total retinal reattachment was achieved in 41 eyes (68.3%). The anatomical success rate was 88% (22/25 eyes) in grade C1-C2 PVR cases, 68.7% (11/15 eyes) in grade C3-D1 PVR cases, and 42% (8/19 eyes) in grade D2-D3 PVR cases. Visual acuity of 0.1 or better was achieved in 80% of eyes with grade C PVR and 61% of eyes with grade D PVR. Visual acuity of 0.4 or better was achieved in 26.9% of eyes with grade C PVR. Macular changes were revealed by fluorescein angiography in 53% of successful eyes. We recommend the use of C3F8 rather than SF6 in the management of rhegmatogenous retinal detachment complicated by PVR. In our experience the anatomical success rate achieved with C3F8 is approximately the same as that achieved with SF6. However permanent retinal reattachment was achieved with a single operation in 87.8% of successful eyes of the present series of patients managed with C3F8 as compared to only 12% of successful eyes of a previous series of patients managed with SF6. The anatomical results achieved with a single operation in the C3F8 series are probably related to the greater longevity of C3F8 as compared to that of SF6.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Acute myeloblastic leukemia presenting as apparent acute otitis media.

Three cases of acute myeloblastic leukemia of FAB-M2 type revealed by an isolated otitis media are reported. This mean of revelation is valuable for early diagnosis and treatment of the disease. A karyotype was performed in two cases and showed an 8;21 translocation. As far as we know, these are the first acute myeloblastic leukemia cases with otitis media reported in which an 8;21 translocation was detected.

Acute Disease↗
PubMed1988

Effect of NaCl and urea concentration comparable to renal medulla on superoxide production by human polymorphonuclear leukocytes.

The influence of hyperosmolarity on superoxide production by polymorphonuclear leukocytes (PMNL) was examined using NaCl and urea as osmotic substances. Superoxide production was inhibited in a hyperosmotic environment produced by high concentrations of these substances with the following IC50: 440 +/- 75 (SD) mOsm/kg for NaCl and 660 +/- 100 for urea. In the case of NaCl, this inhibition was time-dependent and abolished at 4 degrees C. Since PMNL pump out Na+ ion for maintenance of cellular volume in an energy dependent fashion, it was suggested that the inhibition of superoxide production was due to the exhaustion of energy stores. On the other hand, urea inhibition was almost immediate and remained even when preincubation was performed at 4 degrees C. Because the transport of urea through the cell membrane is known to be energy independent, these findings suggested that urea was either an inhibitor of the NADPH oxidase or a scavenger of superoxide anion.

Humans↗
PubMed1988

The development of severe proliferative vitreoretinopathy after retinal detachment surgery. Grade B: a determining risk factor.

A prospective clinical study was conducted to determine wether preoperative proliferative vitreoretinopathy (PVR), grade B, was a significant risk factor in the development of severe PVR after surgery for retinal detachment repair. Two series of consecutive retinal detachments associated with horseshoe retinal tears were compared. The first series included 40 eyes of 40 patients with preoperative PVR, grade O-A. The second series included 30 eyes of 27 patients with preoperative PVR, grade B. All eyes were operated on with conventional microsurgical techniques. At the first operation, no vitrectomies were carried out in any eyes. The incidence of postoperative PVR, grades C and D, was 20% (6/30 eyes) after a single operation in the series of eyes with preoperative PVR, grade B as compared to 0% in the series of eyes with preoperative PVR, grade O-A. The difference between the two groups was statistically significant (P = 0.01). It was also found that the incidence of postoperative proliferative PVR was significantly higher in eyes with preoperative vitreous hemorrhage (30.7%) as compared to eyes with no preoperative vitreous hemorrhage (0%; P = 0.02). Incomplete posterior vitreous detachment without collapse of the vitreous gel occurred significantly more frequently in eyes with preoperative proliferative vitreoretinopathy, grade B (68.4%, than in eyes with preoperative proliferative vitreoretinopathy, grade O-A (27.5%; P = 0.02).

Adult↗
PubMed1988

[Rhegmatogenous retinal detachment and retinal tear with intravitreous hemorrhage].

A retrospective study was conducted on a series of 28 eyes with primary retinal tears associated with vitreous hemorrhage. At initial presentation, the retina was detached in 17 eyes and attached in 11. In the series of eyes with an attached retina, the vitreous hemorrhage was massive in 5 eyes (45%), the average number of retinal tears was 1.36. All eyes showed a retinal tear located in the upper quadrants. Three patients (27%) experienced recurrent vitreous hemorrhage after sealing of the retinal tears. In the series of eyes with a detached retina, the vitreous hemorrhage was massive in 5 eyes (29%) and the average number of retinal tears was 1.9. The retinal detachment was located in the upper quadrants in 16 eyes (94%). Clinical evidence of proliferative vitreoretinopathy was noted, at initial presentation, in 6 eyes (35%). Permanent retinal reattachment was achieved in only 12 eyes (70%). All surgical failures were related to proliferative vitreoretinopathy. In the present series the prognosis of primary retinal tears with significant vitreous hemorrhage was guarded because of recurrent vitreous hemorrhages. The prognosis of primary rhegmatogenous retinal detachments with significant vitreous hemorrhage at initial presentation was guarded because of the high incidence of proliferative vitreoretinopathy.

Adult↗
PubMed1988

[Mucormycosis and diabetes in acute leukemia].

The authors report the case of 5 1/2 year-old boy with insulin-dependent diabetes mellitus revealed during the induction therapy of an acute leukemia of the mixed type, and who presented with an unusual type of pulmonary fungal infection: mucormycosis. It had a favourable outcome with surgical excision preceded and followed by amphotericin B treatment.

Acute Disease↗