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Biomedical subjects

M Bonnet

Publications and source records attributed to M Bonnet.

At least 73 records · Page 4Linked to original sources
PubMed1993

Late recurrences after successful surgery for retinal detachment with macular hole.

Six myopic eyes affected by retinal detachment with macular hole which had been successfully reattached developed recurrent retinal detachment 7-78 months postoperatively. The mean interval between surgery and the recurrent retinal detachment was 13.4 months in five eyes managed with gas tamponade and no choroidal irritation. In an eye managed by scleral buckling with choroidal irritation, the recurrent retinal detachment occurred 78 months postoperatively. The retina was reattached following reoperation in all eyes. However, an eye successfully reattached without choroidal irritation developed four recurrences during the follow-up period. The pathogenesis of late recurrences after successful surgery for retinal detachment with macular hole remains speculative. A number of clinical findings suggest that vitreous traction plays a decisive role.

Adult↗
PubMed1993

Preincubation of Haemophilus influenzae with subinhibitory concentrations of macrolides: influence on human neutrophil chemiluminescence.

Preincubation of Haemophilus influenzae with antibiotics may influence opsonophagocytosis as studied by chemiluminescence. Two strains of H. influenzae (strain 1 [type b] and strain 2 [uncapsulated]) were pretreated with erythromycin, roxithromycin, clarithromycin, and azithromycin for 1 h in Haemophilus test medium (the last 25 min was either without serum or with 10% fresh serum or 10% decomplemented serum). Human neutrophils were stimulated with a pretreated or control inoculum at four different bacterium/neutrophil ratios and tested for luminol chemiluminescence with an LKB luminometer. The results were normalized for bacterium/neutrophil ratio and compared by the two-sided Wilcoxon test. Pretreatment of bacteria with one-half of the MICs of erythromycin, clarithromycin, and roxithromycin produced nonsignificant (P > 0.05) increases in the chemiluminescence response (means of 23% for strain 1 and 4% for strain 2). Pretreatment with azithromycin at one-half of the MIC produced an increase in the chemiluminescence response induced by serum-opsonized strain 1 (320% +/- 36% [mean +/- standard error of the mean]) and strain 2 (107% +/- 20%) (P < 0.05). This increase was concentration dependent: for strain 1, 60% +/- 18% at one-fourth of the MIC to 440% +/- 41% at the MIC; for strain 2, 10% +/- 5% at one-fourth of the MIC to 300% +/- 20% at the MIC. For strain 1, the maximal increase with azithromycin pretreatment (at the MIC) required opsonization with fresh serum. Opsonization with decomplemented serum was associated with a 53% +/- 21% increase; this increase was 28% +/- 3% in the absence of serum. For strain 2, azithromycin reduced the lag phase of the chemiluminescence response induced by the absence of serum but did not alter the chemiluminescence response in the presence of decomplemented serum. A significant contribution of soluble factors in the enhanced response observed with bacteria preincubated with azithromycin was excluded. The increase of the chemiluminescence response with azithromycin pretreatment was probably due to improvement in complement-dependent opsonization for strain 1 and to improvement in both serum-independent and serum-dependent opsonization for strain 2.

Anti-Bacterial Agents↗
PubMed1993

[Treatment of macular detachment complicating optic disk coloboma pits. Long-term results of the photocoagulation-gas combination].

We managed 19 eyes of 19 patients with serous macular detachment associated with optic nerve pits with photocoagulation of the temporal edge of the optic disc combined with intravitreal injection of an expanding gas. SF6 was used in 8 eyes, and C3F8 in 11 eyes at the initial treatment. Eight eyes (42%) had repeated treatment because of failed initial treatment and/or late recurrence(s). Eighteen patients were followed up for 4 to 110 months (mean follow-up: 39 months). At the last examination the macula was attached in 17 of 18 eyes (94.4%). However 3 patients (17.6%) showed a limited serous retinal detachment distant from the macula. The results achieved after single treatment were better with C3F8 than with SF6 (78.5% versus 57% anatomical success rate). During the follow-up period, 5 eyes (27.7%) developed one or two late recurrences. Macular reattachment occurred spontaneously in 2 eyes and after repeated C3F8 injection in 3 eyes. The final visual acuity was improved by 0.1 to 0.6 as compared to the initial visual acuity in 12 patients (66.6%). Ten patients (55.5%) had a final visual acuity > or = 0.5 and > or = Parinaud scale no. 2. We believe that photocoagulation treatment combined with C3F8 intravitreal injection is a valuable approach to the management of serous macular detachment associated with optic nerve pits. However the treatment also shows limitations, in particular the need for repeated treatment in failed eyes and/or eyes with late recurrences.

Adolescent↗
PubMed1993

[Subretinal proliferation and rhegmatogenous retinal detachment].

We reviewed the clinical files of 314 patients (341 eyes) affected by rhegmatogenous retinal detachment who were operated on before any failed attempt to reattach the retina. The study was conducted to elucidate the clinical and prognostic value of subretinal proliferation. Clinical evidence of subretinal proliferation visible at preoperative examination was more frequent in eyes with retinal detachments related to retinogenic retinal breaks (oral dialyses, atrophic holes in lattice) (32.35%) as compared to retinal detachments associated with horse-shoe tears (4.60%) (P < 0.001). The mean duration of retinal detachments with subretinal proliferation was 12 months (range: 3 months to 5 years). Postoperative proliferative vitreoretinopathy occurred in 2.27% (1/44 eyes) of retinal detachments with subretinal proliferation compared with 6.73% (20/297 eyes) of retinal detachments without subretinal proliferation. Permanent retinal reattachment was achieved in all eyes with subretinal proliferation. However postoperative visual acuity of 20/40 or better was obtained in only 34% (15/44 eyes) of eyes with subretinal proliferation compared with 58% (160/275 eyes) of retinal detachments without subretinal proliferation (P < 0.01).

Eye Diseases↗
PubMed1993

[Long-term prognosis of cystoid macular edema after microsurgery of rhegmatogenous retinal detachment].

We reviewed 25 eyes of 24 patients who had undergone successful repair of rhegmatogenous retinal detachment and who showed cystoid macular edema disclosed by routine fluorescein angiography performed 10-12 weeks postoperatively. The follow-up ranged from 18 months to 10 years (average: 60 months). Angiographic CME spontaneously disappeared in 19 eyes (76%). Complete disappearance of CME occurred less than 2 years postoperatively in all eyes. No late recurrence was observed. The final visual acuity was 20/40 or better in 15 eyes (78.9%). The final near reading visual acuity was normal in 16 eyes (84.2%). Angiographic CME was still present in 6 eyes (24%) 2 years postoperatively. It remained unchanged during the follow-up period (average 64 months) in all eyes. Cystoid macular degeneration developed in only 1 of the 6 eyes with chronic angiographic CME. Five of the 6 eyes with chronic CME retained useful near reading visual acuity during the follow-up period. The long-term prognosis of angiographic CME after microsurgical repair of rhegmatogenous retinal detachment appears to be good in most cases.

Fluorescein Angiography↗
PubMed1993

[Microsurgery of retinal detachment in children].

We conducted a retrospective study of 84 retinal detachments in 69 consecutive children under 15 years of age, operated using microsurgical techniques. The goal of this study was to evaluate the prognosis following this surgical approach. Trauma was the most frequent etiology (34.6% of eyes), followed by high myopia (31% of eyes). The other etiologies were varied. Cicatricial retinopathy of prematurity was the most common of them (9.5% of eyes). The series was characterised by the severity of retinal detachment at initial presentation with total retinal detachment in 44% of eyes, detached macula in 70.3% of eyes and severe PVR in 29.8% of eyes. Sixty nine of the 84 eyes were operated on. Thirty two eyes were managed using transscleral microsurgery and 37 eyes (53.6%) required vitrectomy. Permanent retinal reattachment was achieved in 51 of the 69 eyes (73.9%). The present series of retinal detachments in children was highly heterogeneous. Retinal detachments related to retinogenic retinal breaks (atrophic holes and oral dialyses) were more common compared with adult retinal detachments. Their prognosis after surgery was excellent. In contrast traction retinal detachments and detachments related to vitreogenic retinal tears were characterised by a more guarded prognosis. However microsurgical techniques have made the most severe cases, such as grade D2-D3 PVR, giant tears with an inverted posterior flap and detachments after penetrating eye injuries, amenable to surgical management with encouraging results.

Adolescent↗
PubMed1993

[Use of diode laser in transcleral retinal photocoagulation].

Transscleral retinal photocoagulation using a diode laser emitting infrared radiation (810 nm) was performed on 8 rabbits. Examination was performed at 2 days, one month and three months after photocoagulation. The retinal burns were examined by light and electron microscopy and were found to be similar to those produced by argon and krypton photocoagulations. Histopathologic evaluation of the lesions demonstrated an intact sclera overlying the chorioretinal lesions. The results of the present experimental study support the hypothesis that transsccleral retinal photocoagulation using diode laser in selected indications may be a valuable alternative to cryotreatment and diathermy in the human eye. The absence of scleral damage and pigmented epithelium cell dispersion as well as the decreased break down of the blood ocular barrier after transscleral diode laser photocoagulation are the main advantages of the technique as compared to transscleral diathermy and cryotreatment.

Animals↗
PubMed1992

Prognostic value of new retinal tears associated with the development of postoperative proliferative vitreoretinopathy.

We prospectively evaluated for the presence of new retinal tears 60 eyes of 60 patients who developed recurrent retinal detachment complicated by proliferative vitreoretinopathy (PVR) after surgery for primary rhegmatogenous retinal detachment. New retinal tears associated with the development or recurrence of postoperative PVR were disclosed in 27 eyes (45%). New tears were categorized into two distinct groups: (1) peripheral new tears and (2) posterior new tears. Peripheral new tears were disclosed in 11 eyes. They were invariably located at the posterior edge of the vitreous base and showed a prevalence in the inferior quadrants. The prognosis for permanent retinal reattachment after reoperation was not influenced by the presence of peripheral new tears. Posterior new tears were disclosed in 19 eyes. They were located in the mid-periphery or close to the posterior pole. They were more frequent in grade D PVR (57.7%) compared with grade C PVR (11.7%) (P less than 0.01). Posterior new tears were associated with a poor prognosis. In grade D PVR the anatomic success rate following repeated surgery was only 13.3% (2/15 eyes), whereas all eyes with grade D PVR and no posterior new tears were successfully reattached (P less than 0.001). Failures to reattach the retina were related to recurrent PVR. It is concluded that the development of posterior new tears in postoperative PVR reflects a severe and active PVR process.

Adolescent↗
PubMed1992

Dantrolene inhibits halothane-induced membrane reorganization. A study using 31P-NMR and differential scanning calorimetry.

The action of the relaxing agent dantrolene on dipalmitoylphosphatidylcholine (DPPC) model membranes in the presence and absence of the general anesthetic halothane has been investigated by DSC and 31P-NMR. Dantrolene has a weak effect on both the thermodynamic and NMR parameters of the pure model membrane. When halothane is present in the system, the relaxing agent acts to counterbalance the strong anesthetic-induced membrane perturbation. This is reflected in DSC experiments by a change of the enthalpy variation (delta H) and of the main gel-to-fluid phase transition temperature (Tc) towards the values of the pure lipid system. The amount of halothane-induced small tumbling vesicles, as detected by 31P-NMR by the superposition of an isotropic line on a lamellar-type powder spectrum, is considerably reduced upon dantrolene addition. This means that the relaxing agent "cures" the membrane de-structuring action promoted by halothane. Membranes first treated with dantrolene are also protected from the halothane perturbation. So, the relaxing agent is both "curative" and "preventative" against halothane. The optimum effect is obtained for 1 dantrolene molecule per ca 34 halothane molecules. The mechanisms of action were discussed in relation to membrane fluidity.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1992

In vitro and in vivo intraleukocytic accumulation of azithromycin (CP-62, 993) and its influence on ex vivo leukocyte chemiluminescence.

The accumulation of azithromycin in phagocytic cells was studied both in vitro by using a radiolabelled drug and a bioassay and in vivo for 12 volunteers receiving 1.5 g (total dose) orally within 3 days. In vitro, neutrophils and unfractionated blood leukocytes accumulated azithromycin up to 160-fold the extracellular concentration within 1 h at 37 degrees C but less than 3-fold at 4 degrees C. Dead cells accumulated up to 30-fold azithromycin, whereas NaF-treated cells accumulated up to 60-fold arithromycin. The mean efflux from preloaded cells was at most 31.0% +/- 10.6% (standard error of the mean) of the cell-associated concentration within 4 h of incubation at 37 degrees C in drug-free buffer. In vivo, the azithromycin concentration was 45.2 +/- 6.1 mg/liter of intracellular fluid at 2 h after the third dose and 36.6 +/- 8.3 mg/liter at 1 week thereafter. The corresponding concentrations in serum were 0.2 +/- 0.1 (2 h) and less than 0.05 (1 week). The luminol-enhanced chemiluminescence response induced by phorbol myristate acetate, opsonized zymosan, and two opsonized strains of Haemophilus influenzae (a type b capsulated strain and a noncapsulated strain) was also studied ex vivo by using the blood leukocytes from the 12 test volunteers and 4 control volunteers at 2 and 6 h after the third oral dose of azithromycin and at 2, 4, and 7 days thereafter. Azithromycin did not influence this response despite high levels of cellular accumulation.

Adult↗
PubMed1992

[C2F6 in the treatment of retinal detachment associated to PVR: therapeutic trial].

We conducted a clinical trial on C2F6 as a retinal tamponade in the management of retinal detachment with proliferative vitreoretinopathy. Twenty seven eyes of 27 consecutive patients were enrolled in the study. Permanent retinal reattachment was achieved in 21 eyes (78%). The anatomic success rate was 85% in eyes with grade B PVR (17/20 eyes), and 57% in eyes with grade C and D PVR (4/7 eyes). The success rate was as high as that achieved in a previous series of eyes managed with the use of C3F8 combined with the same surgical technique. C2F6 shares the advantages of C3F8 in the management of retinal detachments complicated by proliferative vitreoretinopathy. However its absorption is more rapid as compared to C3F8. This is an advantage with regard to the postoperative disadvantages of gas tamponade. Further clinical use on a larger series of patients is required to confirmed the preliminary results.

Cryosurgery↗
PubMed1992

[Incidence of signs indicating psoriatic rheumatism in radiological involvement of fingers and toes. Apropos of 193 cases of psoriatic arthropathy].

On the basis of 193 cases of psoriatic arthropathy, the authors sought the incidence and rapidity of onset of signs suggestive of this type of rheumatic disorder when there are radiological lesions of the fingers and toes. They conclude that when such radiological lesions exist, signs suggestive of psoriatic arthropathy are frequent (90%), early (85% of cases of psoriatic arthropathy present for less than 5 years) and predominantly involve the distal parts of the fingers and toes (85.5%). The authors consider that the signs which distinguish psoriatic arthropathy from rheumatoid arthritis are due to an extrasynovial process of enthesopathic origin.

Adolescent↗
PubMed1992

[Late macular pseudo-hole after surgical peeling of a premacular membrane].

We present three clinical cases showing a pseudo macular hole that developed late after an uneventful surgical removal of an epiretinal membrane. The pseudo macular hole developed 3 to 19 months postoperatively. The macular changes seen in all cases showed stricking differences when compared with pseudo macular holes associated with epiretinal membranes. A hypothesis is suggested for the pathogenesis.

Diagnosis, Differential↗
PubMed1991

Halothane-induced membrane reorganization monitored by DSC, freeze fracture electron microscopy and 31P-NMR techniques.

The effect of the volatile anaesthetic halothane on the structure and dynamics of lipid multilayers (dimyristoyl- and dipalmitoylphosphatidylcholine, DM- and DP-PC, aqueous dispersions) was studied using Differential Scanning Calorimetry (DSC), Freeze Fracture Electron Microscopy and solid state phosphorus-31 Nuclear Magnetic Resonance (31P-NMR). The action of the drug depends upon the halothane-to-lipid molar ratio, Ri, and temperature. With DPPC lipids, three main regions can be distinguished: i) 0 less than Ri less than 0.7, ii) 0.7 less than Ri less than 2 and iii) Ri greater than 2. As Ri increases in the first region, a linear decrease in the main gel-to-fluid phase transition temperature (Tc), a broadening in the DSC transition peak and a lowering in the enthalpy variation (delta H), are observed. A minimum in delta H is reached at Ri = 0.7. In this region, 31P-NMR spectra indicate that the multibilayer structure is maintained. In the second region, Tc still decreases with the same slope, but delta H increases up to a plateau value for Ri = 2. In the lipid fluid phase, an isotropic NMR line appears superimposed on the powder pattern that corresponds to a lamellar phase. For Ri greater than 2, Tc and delta H remain almost constant. At values of temperature that are greater than Tc, a growing isotropic line occurs in 31P-NMR spectra. This means a new supramolecular structure made of lipids and halothane is stabilized. This structure has been characterized as small vesicles of about 400 A to 600 A diameter by Freeze Fracture electron microscopy observations. With DMPC and low ratios (Ri less than or equal to 2), DSC and NMR results are similar to those obtained for DPPC. However, the minimum delta H is reached at Ri = 0.2 and the decrease in Tc is faster than for DPPC when Ri increases from 0. For Ri greater than 2, while Tc and delta H remain constant as in the case of DPPC, 31P-NMR spectra of DMPC systems show a superimposition of an isotropic line and two powder patterns, which correspond to small tumbling vesicles, a possible hexagonal phase and a lamellar phase respectively. Halothane, thus acts on model membranes in two different steps: at low Ri the bilayer is disturbed but keeps its structure. Whereas for higher drug concentrations, a new organization of lipids seems to be stabilized for T greater than Tc.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1991

Serous macular detachment associated with optic nerve pits.

Between September 1972 and March 1989, we examined 25 eyes of 24 patients exhibiting optic nerve-head pits associated with serous macular detachment. We followed 21 patients for a period of 1-15 years (mean, 62 months). Various treatment modalities were applied, depending on the time of initial examination. Five eyes underwent no treatment and three eyes underwent two distinct treatment modalities. Photocoagulation treatment was performed in ten eyes. Argon laser photocoagulation was combined with intravitreal injection of pure SF6 in eight eyes and of C3F8 in three. Intravitreal injection of pure C3F8 without photocoagulation was carried out in two eyes. The results of biomicroscopy of the vitreous gel and of fluorescein angiography and the responses to the various treatment modalities support the hypothesis that the mechanism underlying serous macular detachment complicating optic nerve-head pits is traction retinal detachment combined with a rhegmatogenous component in the roof of the optic pit.

Adolescent↗
PubMed1991

Management of retinal detachment after penetrating eye injury.

Between December 1981 and April 1989 the authors operated on 61 eyes presenting with retinal detachment after penetrating eye injury. Air or expanding gases were used for retinal tamponade. The follow-up between complete gas absorption and last examination ranged from 8 months to 8 years (mean, 29 months). Retinal reattachment was achieved in 50 eyes (81.9%). Anatomic success was achieved by a single operation in 43 eyes (70.5%). A postoperative visual acuity of 20/40 or better was achieved in 46% of the eyes. The factors found to influence the postoperative outcome adversely include (1) association of severe blunt trauma (P less than 0.05), (2) anterior proliferative vitreoretinopathy (PVR) involving two or more quadrants (P less than 0.01), and (2) retinotomies (P less than 0.007).

Adolescent↗