Membrane-bound oxygen reductases of the anaerobic sulfate-reducing Desulfovibrio vulgaris Hildenborough: roles in oxygen defence and electron link with periplasmic hydrogen oxidation.

Cytoplasmic membranes of the strictly anaerobic sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough contain two terminal oxygen reductases, a bd quinol oxidase and a cc(b/o)o3 cytochrome oxidase (Cox). Viability assays pointed out that single Δbd, Δcox and double ΔbdΔcox deletion mutant strains were more sensitive to oxygen exposure than the WT strain, showing the involvement of these oxygen reductases in the detoxification of oxygen. The Δcox strain was slightly more sensitive than the Δbd strain, pointing to the importance of the cc(b/o)o3 cytochrome oxidase in oxygen protection. Decreased O2 reduction rates were measured in mutant cells and membranes using lactate, NADH, ubiquinol and menadiol as substrates. The affinity for oxygen measured with the bd quinol oxidase (Km, 300 nM) was higher than that of the cc(b/o)o3 cytochrome oxidase (Km, 620 nM). The total membrane activity of the bd quinol oxidase was higher than that of the cytochrome oxidase activity in line with the higher expression of the bd oxidase genes. In addition, analysis of the ΔbdΔcox mutant strain indicated the presence of at least one O2-scavenging membrane-bound system able to reduce O2 with menaquinol as electron donor with an O2 affinity that was two orders of magnitude lower than that of the bd quinol oxidase. The lower O2 reductase activity in mutant cells with hydrogen as electron donor and the use of specific inhibitors indicated an electron transfer link between periplasmic H2 oxidation and membrane-bound oxygen reduction via the menaquinol pool. This linkage is crucial in defence of the strictly anaerobic bacterium Desulfovibrio against oxygen stress.

Respiratory complex III dysfunction in humans and the use of yeast as a model organism to study mitochondrial myopathy and associated diseases.

The bc1 complex or complex III is a central component of the aerobic respiratory chain in prokaryotic and eukaryotic organisms. It catalyzes the oxidation of quinols and the reduction of cytochrome c, establishing a proton motive force used to synthesize adenosine triphosphate (ATP) by the F1Fo ATP synthase. In eukaryotes, the complex III is located in the inner mitochondrial membrane. The genes coding for the complex III have a dual origin. While cytochrome b is encoded by the mitochondrial genome, all the other subunits are encoded by the nuclear genome. In this review, we compile an exhaustive list of the known human mutations and associated pathologies found in the mitochondrially-encoded cytochrome b gene as well as the fewer mutations in the nuclear genes coding for the complex III structural subunits and accessory proteins such as BCS1L involved in the assembly of the complex III. Due to the inherent difficulties of studying human biopsy material associated with complex III dysfunction, we also review the work that has been conducted to study the pathologies with the easy to handle eukaryotic microorganism, the yeast Saccharomyces cerevisiae. Phenotypes, biochemical data and possible effects due to the mutations are also discussed in the context of the known three-dimensional structure of the eukaryotic complex III. This article is part of a Special Issue entitled: Respiratory complex III and related bc complexes.

[The myopic vitreous. Why is its examination so difficult?]. / Le vitré du myope fort. Pourquoi son examen est-il si difficile ?

The examination of a high myopic vitreous is difficult for several reasons, including optic phenomena and vitreous liquefaction. The diagnosis of a posterior vitreous detachment may be problematic and confused with the observation of a large lacuna posterior margin.

Oxygen reduction in the strict anaerobe Desulfovibrio vulgaris Hildenborough: characterization of two membrane-bound oxygen reductases.

Although Desulfovibrio vulgaris Hildenborough (DvH) is a strictly anaerobic bacterium, it is able to consume oxygen in different cellular compartments, including extensive periplasmic O2 reduction with hydrogen as electron donor. The genome of DvH revealed the presence of cydAB and cox genes, encoding a quinol oxidase bd and a cytochrome c oxidase, respectively. In the membranes of DvH, we detected both quinol oxygen reductase [inhibited by heptyl-hydroxyquinoline-N-oxide (HQNO)] and cytochrome c oxidase activities. Spectral and HPLC data for the membrane fraction revealed the presence of o-, b- and d-type haems, in addition to a majority of c-type haems, but no a-type haem, in agreement with carbon monoxide-binding analysis. The cytochrome c oxidase is thus of the cc(o/b)o3 type, a type not previously described. The monohaem cytochrome c553 is an electron donor to the cytochrome c oxidase; its encoding gene is located upstream of the cox operon and is 50-fold more transcribed than coxI encoding the cytochrome c oxidase subunit I. Even when DvH is grown under anaerobic conditions in lactate/sulfate medium, the two terminal oxidase-encoding genes are expressed. Furthermore, the quinol oxidase bd-encoding genes are more highly expressed than the cox genes. The cox operon exhibits an atypical genomic organization, with the gene coxII located downstream of coxIV. The occurrence of these membrane-bound oxygen reductases in other strictly anaerobic Deltaproteobacteria is discussed.

[Corneal tattooing for iris defects]. / Le tatouage cornéen chirurgical dans la prise en charge des défects de l'iris.

PURPOSE: Defects in the iris are associated with clinically significant visual and cosmetic anomalies. When iris reconstruction with artificial iris implantation or an iris suture technique is impossible, a third possibility exists: intrastromal corneal tattooing. PATIENTS: and method: We report this little known surgery in three patients with a sectoral or total iris defect following injury. The procedure is detailed. RESULTS: With an 11-month follow-up (range, 7-13 months), this procedure was effective in providing functional and cosmetic repair. Photophobia and diplopia disappeared, with no side effects. CONCLUSION: The repair of iris anomalies requires a certain surgical experience but offers patients a significant functional improvement. Choosing the right procedure for each particular case can be difficult. Corneal tattooing remains a simple surgery adapted to often fragile eyes.

[Endogenous Candida endophthalmitis in drug misusers injecting intravenous buprenorphine]. / Endophtalmie endogène à Candida secondaire à l'utilisation de la buprénorphine par voie intraveineuse.

PURPOSE: To analyze patients presenting ocular candidiasis caused by intravenous drug addiction to buprenorphine. PATIENTS AND METHODS: We have listed all the cases of endogenous fungal endophthalmitis hospitalized between 1996 and 2005 in the ophthalmology department of the university-affiliated hospital of Rouen, France. Posterior vitrectomy was performed for each patient, with direct examination and bacterial and fungal cultures. The treatment was begun both with an intravitreal injection of amphotericin B and oral fluconazole, modified in the event of resistance. RESULTS: Seven men, drug addicts, all using intravenous buprenorphine users, were included in the study. The vitreal culture revealed four cases of Candida albicans candidiasis and one case of Candida tropicalis candidiasis. In two cases, oral fluconazole had to be replaced with oral voriconazole. Of the seven patients, three evolved unfavorably despite treatment. DISCUSSION: Intravenous drug use is known to be a risk factor for ocular candidiasis. However, buprenorphine does not seem to be related to endogenous endophthalmitis, since this was also observed among patients using methadone or heroine. Salivary contact during the preparation of the syringe being used for the injection of the substitute appears to be the source of the candidemia in our series and in the literature. CONCLUSION: Inappropriate intravenous use of oral buprenorphine in drug users is a significant risk factor of endogenous fungal endophthalmitis. Visual monitoring by pharmacists of the oral intake of buprenorphine seems essential. We underline the advantages of removing the vitreous in ocular candidiasis.

[Vitreomacular traction]. / Syndrome de traction vitréomaculaire.

Vitreomacular traction syndrome is an entity in which there is partial detachment of the posterior vitreous with persistent vitreomacular adhesion. This adherence may cause a maculopathy with vision loss. Using optical coherence tomography (OCT), the diagnosis is more frequent and more accurate. There is great variability in the posterior and peripheral areas of vitreous attachment. Careful examination and early diagnosis are important because vitrectomy and release macular traction may improve visual acuity in most cases.

Results of surgery on macular holes that develop after rhegmatogenous retinal detachment.

AIMS: To evaluate the characterics and surgical prognosis of macular holes that develop after rhegmatogenous retinal detachment repair. DESIGN: Retrospective, interventional, consecutive case series. METHODS: The case records of nine patients who developed a new full-thickness macular hole after prior RD repair were reviewed over 6 years. Optical coherence tomography (OCT) confirmed these holes. They were offered surgical repair with a median follow-up of 13.3 months (1-63 months). Main outcomes included preoperative vitreo-macular status, OCT evaluation and postoperative visual acuity. RESULTS: 1007 eyes underwent surgery for prior retinal detachment between August 1999 and September 2005. Nine eyes developed a full-thickness macular hole (prevalence 0.9%): five developed after scleral buckling surgery, one after pneumatic retinopexy and three after primary vitrectomy. The mean time to macular hole diagnosis after RD was 2.9 months (0.5-18). All patients underwent macular hole surgery by the same surgeon. At 1 month, macular hole repair was noticed in eight eyes. In this group, visual acuity at a median of 11.9 months of follow-up was 20/125 (20/400 - 20/63). Three eyes had an improvement of more than three Snellen lines. CONCLUSIONS: Macular holes developing after RD repair is a rare complication (less than 1%). Its physiopathological mechanisms are not well known. Conventional macular hole surgery including pars plana vitrectomy, inconstant internal limiting membrane delamination and long-acting gas tamponade seems to achieve to macular reattachment (89%). The visual outcome seems conditioned by the macular status noticed during the RD.

[Multifocal placoid pigment epitheliopathy as a manifestation of ophthalmological sarcoidosis]. / Epithéliopathie en plaques, manifestation ophtalmologique de la sarcoïdose?

INTRODUCTION: An ocular manifestation may be the only location of a general disease. OBSERVATION: This is the case of a young female patient who developed placoid epitheliopathy at the age of 24. Four years later, sarcoidosis was diagnosed, with multivisceral damage and severe ophthalmological impairment, as well as skin, renal, and pulmonary involvement. DISCUSSION: Sarcoidosis and placoid epitheliopathy have similar features: the substrate, certain ophthalmological manifestations, and skin disorders. A number of atypical cases of placoid epitheliopathy with inflammatory ocular signs have been described in the literature. In parallel, cases of sarcoidosis with retinal damage, in particular to pigment epithelium, have been reported. Our recommendation is to use specific tests to investigate sarcoidosis whenever placoid epitheliopathy is diagnosed, given the vital and functional risk associated with sarcoidosis.

[Cerebrovascular accident following photodynamic therapy]. / Accident vasculaire cérébral après photothérapie dynamique.

INTRODUCTION: Severe complications following dynamic phototherapy are very rare. We report the case of a patient who went into a vigilant coma after a second dynamic phototherapy treatment. CASE REPORT: A 75-year-old man reported to the ophthalmology consultation for subfoveal choroidal neovascularization of the right eye. The first course of phototherapy treatment was administered that day. After 3 months, persistent progression of angiographic lesions led to the decision to perform a second course of dynamic phototherapy. Twelve hours later, finger paraesthesia occurred, followed 1 h later by the onset of vigilant coma secondary to massive right frontoparietal ischemia. The patient died following complications of the coma. CONCLUSION: More severe complications have been described, in particular cases of syncope or chest pain with no infarction. It is thought that Verteporfin may have played a role in our patient's brain ischemia. As Verteporfin continues to be widely used, physicians must be alert to the possibility of serious adverse events associated with its use.

[Surgical results of retinal detachment with unseen retinal breaks]. / Résultats chirurgicaux des décollements de rétine sans déhiscence visible.

BACKGROUND: The treatment of retinal detachment (RD) with unseen breaks has not been clearly defined. The aim of this study was to evaluate surgical results of these RDs using two different techniques. PATIENTS AND METHODS: We conducted a retrospective study including consecutively operated RDs in our department between 2001 and 2006. Twenty-two RDs were identified. In eight eyes (36.4%), conventional scleral buckling was performed (with or without subretinal fluid drainage). In 14 eyes (63.6%), vitrectomy associated with cryopexy or endolaser impact was performed. Circumferential buckling was achieved in ten cases. RESULTS: These operated patients account for 2.5% of the RDs followed up in our department between January 2001 and June 2006 (887 patients). The eyes were predominantly pseudophakic (86.4%), with inferior RD (59.1%). The patients had described functional signs for a mean of 56 days (2-240 days). Sixteen eyes (73%) were reattached after the primary procedure. The primary reattachment rates at 1 month were 37.5% in the scleral buckling group versus 86.4% in the vitrectomized group. The final retinal reattachment rate was 86.4%. CONCLUSIONS: In our study, the situation where breaks are unseen during retinal detachment surgery is uncommon (2.5%), occurring most often with inferior retinal detachment in pseudophakic eyes. This seems to indicate better retina reattachment after vitrectomy associated with a circumferential buckling in first intention. However, a study including a larger number of patients would be necessary to confirm our results.

[Meningococcus endophthalmitis without meningitidis]. / Endophtalmie à méningocoque sans méningite.

Meningococcus endophthalmitis is exceptional. We report a case of ocular damage following type C meningococcus septicemia with no meningitis. A 20-year-old man reported to the emergency unit for polyarthritis pain in various joints, associated with chills, nausea, and diarrhea without fever. Ophthalmological examination revealed uveitis. A few days later, endogenous endophthalmitis was suggested because of a worsening general condition and fever spells to 39 degrees C. A hemoculture sampled on the patient's admission 4 days earlier revealed Neisseria meningitidis positivity. Meningococcus septicemia with no meningitis was diagnosed. Before the introduction of antibiotics, meningococcus meningitis was unfortunately frequent and ocular septic embolism was not a rare occurrence. The diagnosis of meningococcemia was delayed in our patient because of the atypical symptomatology and ocular manifestations in the forefront. As with any endogenous endophthalmitis, prognosis is bleak and it should be raised whenever suspected uveitis does not react to standard treatment.

[Advantages of amniotic membrane transplantation in eye surface diseases]. / Intérêt des greffes de membranes amniotiques dans les pathologies oculaires de surface.

Amniotic membrane transplantation is now a widely adopted technique in the field of eye surface diseases. Depending on the indication, the amniotic membrane can be used as either a graft or a patch. When used as a graft, the amniotic membrane serves as a substrate for regrowth of deficient epithelium; the aim is to integrate this membrane. The basal membrane reinforces the adhesion and differentiation of the corneal epithelial cells, facilitates their migration, and prevents their apoptosis. When used as a patch, the amniotic membrane is sutured epithelium-down so as to maximize the concentration of biological factors delivered by this membrane: the membrane covers the diseased cornea and acts as a biological bandage and analgesic. The best indications for amniotic membrane grafts are acute chemical burns and trophic corneal ulcers refractory to all medical treatment. When these ulcers are perforated or in the early stages of perforation, it is best to use multiple layers of amniotic membrane, restoring the thickness of the cornea. In cases of confirmed limbal deficiency, amniotic membrane grafts may be a useful complement to the necessary limbal stem cell grafts. In the future, amniotic membranes will provide an indispensable support for the expansion of cultured stem cells. Amniotic membrane grafts may also be used to reconstruct the conjunctiva following the exeresis of symblepharons or conjunctival tumors. However, the use of this technique is currently limited to diseases with little inflammation and no extensive fibrosis.

[Surgical management of nontraumatic corneal perforations: an 8-year retrospective study]. / Prise en charge chirurgicale des perforations cornéennes non traumatiques: étude rétrospective sur 8 ans.

PURPOSE: Treatment of nontraumatic corneal perforation is a difficult task. The aim of our study was to retrospectively analyze predisposing conditions leading to perforation, surgical treatments, and visual outcomes. METHODS: Fifty-six patients were admitted in our department for a nontraumatic corneal perforation between 1997 and 2004. Mean patient age was 69 years (range, 16-95 years) and the mean follow-up was 20.5 months (range, 6-96 months). RESULTS: The diseases associated with perforations were neurotrophic ulcer in 24 cases (43%), peripheral immunologic ulcer in ten cases (18%), dry eye in six cases (11%), and infectious keratitis in seven cases (13%). All patients had specific adapted medical treatment before surgery. As a first procedure, we used cyanoacrylate glue in 14 cases (50% anatomic success), multilayer amniotic membrane transplantation in 23 cases (100% anatomic success), conjunctival flap in six cases, peripheral lamellar graft in three cases (33% anatomic success), emergency penetrating keratoplasty in 13 cases (31% anatomic success), and one patient's eye had to be eviscerated. Several surgical procedures were necessary in 16 cases (28%), nine patients needing total conjunctival flap at the end. We were able to achieve tectonic stability in 91% of eyes and 32% of patients recovered useful visual acuity between 20/400 and 20/50. CONCLUSION: Amniotic membrane transplantation is an effective method for managing corneal perforations and usually does not need a further reconstructive procedure. Visual outcome is poor when peripheral or central keratoplasty are needed. We recommend a conjunctival flap when descemetocele or perforation recurs despite previous surgical management.

[Intraocular fluids analysis for etiologic diagnosis of presumed infectious uveitis]. / Intérêt des prélèvements intraoculaires dans le diagnostic étiologique des uvéites présumées infectieuses.

PURPOSE: To study the etiologic distribution of patients with presumed infectious uveitis who underwent ocular fluid analysis. PATIENTS AND METHODS: We retrospectively analyzed vitreous and or aqueous humor samples of patients with presumed infectious uveitis, referred to the department of Ophthalmology of the University Hospital of Rouen, France, between January 1997 and June 2004. We excluded patients with postsurgical or endogenous endophthalmitis. We noted clinical features and intraocular sample analysis methods for each pathogen. RESULTS: The study included 42 patients, 24 men and 18 women, aged between 6 and 79 years (mean, 39.5 years). Uveitis was unilateral in 88% of cases and bilateral in 12%. Posterior uveitis was predominant (52%), followed by panuveitis (24%), anterior (14%), and intermediate uveitis (10%). Aqueous humor and vitreous analysis confirmed etiological diagnosis for 13 of 41 patients (31%) and three of six cases (50%), respectively. Inflammation was controlled or stabilized in all cases. The most pejorative visual outcome was observed for candidiasis and viral retinitis. Positivity of intraocular samples was variable, depending on the suspected pathogen, with results similar to those reported in other studies. DISCUSSION: Atypical features in potential infectious uveitis justify ocular paracentesis or vitrectomy, which are more efficient since molecular biological tools have become available. Sensitivity of aqueous humor analysis is high for posterior uveitis and suspicion of viral retinitis. New molecular variants applied to ocular samples will improve the etiological diagnosis of infectious uveitis, particularly for pathogens that are difficult to culture, such as fungi and bacteria.

Advanced glycation end products can induce glial reaction and neuronal degeneration in retinal explants.

BACKGROUND/AIMS: Neuronal degeneration has been reported to occur in diabetic retinopathy before the onset of detectable microvascular abnormalities. To investigate whether advanced glycation end products (AGE) could be directly responsible for retinal neurodegeneration, retinal explants were incubated with glycated bovine serum albumin (BSA). METHODS: Retinal explants obtained from non-diabetic adult rats were incubated 4 days with or without 200 mug/ml glycated BSA. Neural apoptosis was quantified by terminal dUTP nick end labelling (TUNEL) binding and immunostaining with anti-cleaved caspase-3 antibody. Expression of glial fibrillary acidic protein (GFAP) was localised by immunofluorescence. RESULTS: TUNEL and cleaved caspase-3 positive cells increased significantly by 2.2-fold and 2.5-fold in retinal explants incubated in glycated BSA (p<0.05), respectively. The ganglion cell layer was the most sensitive retinal layer to the glycated BSA. Neuronal degeneration was confirmed by the increased GFAP labelling in Müller glial cells from retinal explants treated with glycated BSA. CONCLUSION: These results suggest that AGE could induce retinal neurodegeneration in the absence of blood perfusion. Cells in the ganglion cell layer appeared to be the most sensitive as in diabetic retinopathy and its animal models. AGE toxicity could therefore contribute to the early pathological mechanisms of diabetic retinopathy.