[Long term postural myopic shift assessment after posterior iris-claw aphakic intraocular lens implantation]. / Résultats à long terme de la bascule posturale myopique après implantation d'un implant clippé postérieurement à l'iris.

PURPOSE: Posterior chamber iris-claw intraocular lens (IOL) is often used in aphakic eyes with inadequate capsular support. Postoperatively, patients may describe better capabilities for near reading in a face-down position. The goal was to evaluate the indications, visual outcomes and complications of this IOL and to compare postoperative spherical equivalent between the prone and the face-down position. MATERIALS AND METHODS: Retrospective single-center case series of 31 eyes of 28 patients who underwent surgery between 2007 and 2016. Visual outcomes, early and late complications were analyzed. The refractive measurements were also assessed using a portable refractometer in prone and face-down position for each patient. The spherical equivalents were then compared. RESULTS: The mean follow up was 29 months (3-73). The final mean corrected visual acuity (0.17±0.5 SD LogMar) was significantly better than preoperatively (0.5±0.50 SD LogMar) (P<0.05). Postoperative refractive error was within±2 diopters of emmetropia in 95 % of patients. The mean spherical equivalents in prone and face down position were different (P<0.05),-0.44 diopters (-4;+2.75) and-1.38 diopters (-5.25; 1) respectively. A mean myopic shift of-0.95 diopters (-5.25; 1.00) was observed in face down position. Cystoïd macular edema (6 %) and IOL disenclavation (9.6 %) were the main complications. DISCUSSION: A posterior iris-claw intraocular lens appears to be an effective and relatively safe IOL to treat aphakia with poor capsular support. When the patient's head is bent forward, a mean myopic shift of 1 diopter is observed. This may support the idea that this IOL could be considered as an accommodative implant. Anterior movement of the iris-IOL complex due to gravity may be responsible for this myopic shift.

[Orbital neurenteric cyst. A case report and review of the literature]. / Kystes neurentériques de l'orbite. À propos d'un cas et revue de la littérature.

INTRODUCTION: Neurenteric cysts defined as a cyst lined by endodermal-type epithelium are extremely rare. We report a rare case of an orbital neurenteric cyst. CASE REPORT: A 19-year-old female presented with an orbital cyst tumor that had cosmetic consequences. The signal of the cyst was not enhanced after administration of gadolinium on MRI examination. The patient underwent surgery due to the increase in size of the tumor. A complete cyst removal including the cyst wall through the inferior palpebral fold was performed. The histological examination confirmed the diagnostic of neurenteric cyst. The patient was discharged home in excellent condition. CONCLUSION: This report discusses the clinical presentation, neuroradiological aspect, pathological findings and therapeutic consideration of the neurenteric cyst. We described a rare case of orbital neurenteric cyst. Due to the local recurrence rate observed after partial resection, the goal of the surgery should be a total resection of the cyst with the cyst wall.

[Early macular edema after phacoemulsification and suspected overdose of cefuroxime: report of six cases]. / Œdème maculaire après phacoémulsification et suspicion de surdosage en céfuroxime : à propos de 6 cas.

Antibiotic prophylaxis by intracameral cefuroxime injection, 1mg/0.1 mL after cataract surgery is increasing in popularity. Several cases of early postoperative macular edema have recently been reported after cefuroxime injection, most of them due to accidental cefuroxime overdose. We report six additional cases of macular involvement after cataract surgery, with intracameral cefuroxime injection imputed to cause retinal toxicity. Formal proof of cefuroxime overdose has never been possible, due to rapid wash-out in a few hours and the diagnosis of the macular edema the day after surgery or within a few days. Thus, this strong suspicion is based on clinical, pharmacokinetic, tomographic and retinographic criteria. In our series of six cases, the first four patients involved the same surgeon in the same hospital, and two of them on the same day. For the sixth case, the diagnosis was made retrospectively and based on history and medium-term tomographic characteristics. All the patients underwent optical coherence tomography (OCT) relatively early. As early as day one after surgery, there is macular edema predominantly in the outer retinal layers associated with serous retinal detachment, similar to the cases described in the literature. In the late stage, three patients had functional impairment related to photoreceptor damage on OCT. Three cases are described with additional retinal imaging (angiography, autofluorescence) to better characterize this macular toxicity associated with cefuroxime.

[Screening method for angle closure and angle closure glaucoma using scanning laser polarimeter GDxVCC and photodynamic gonioscopy in a darkened room. One-year outcomes of systematic peripheral iridotomy]. / Méthode de dépistage du glaucome chronique par fermeture de l'angle basée sur l'utilisation systématique du GDxVCC et de la gonioscopie photodynamique. Résultats à un an d'une iridotomie systématique.

INTRODUCTION: Angle closure glaucoma, a recognized major world health issue disproportionately affecting women and Asians, is not often considered in our European populations, normotensive subjects, myopic patients, or subjects with a deep anterior chamber. Early diagnosis is worthwhile, as laser peripheral iridotomy (LPI) is an effective one-step treatment of the causal mechanism. PATIENTS AND METHODS: We have performed a retrospective study of patients who underwent an LPI, the indication for which was based on "photodynamic" gonioscopy in a darkened room showing iridotrabecular contact in darkness. Such photodynamic gonioscopy was motivated by the presence of even minute defects in the nerve fiber layer as seen on the GDxVCC or the presence of a Van Herick sign (narrow limbal anterior chamber depth). RESULTS: One hundred and three eyes of 103 patients underwent LPI and a minimum 1-year follow-up (mean follow-up almost 2 years). Mean age was 63.7±11.8 years, and women accounted for 63.1% of cases. The vast majority (78.6%) of patients had neither glaucoma nor ocular hypertension. There were 60.1% hyperopes and 39.9% myopes. Over half (57%) had a deep or a very deep anterior chamber. After LPI, there was immediate deepening of the limbal depth of the anterior chamber in 100% of cases. The aqueous humor that flowed forward was almost always viscous-looking. After 1 year, the IOP was 1.3mm Hg±2.4 lower (P<.001) (t test). All patients who had experienced morning headaches (44% of patients) were relieved of this symptom. GDxVCC after 1 year was clearly improved in 18% of cases, slightly improved in 20%, stable in 50%, slightly worse in 11% of cases, and clearly worse in 1%. Cases treated at an earlier stage had a better improvement in GDxVCC. DISCUSSION: Our study shows frequent chronic angle closure in our European population even with deep anterior chambers. Absence of a Van Herick sign does not rule out angle closure at night. A photodynamic gonioscopy with the Goldmann three-lens mirror (to avoid unintentional indentation with the small diameter lenses in these normotensive eyes) should be performed in a darkened room. LPI is an effective one-step treatment of the underlying cause, that is particularly beneficial if performed early.

Driving habits in glaucoma patients.

PURPOSE: Glaucoma is a progressive optic neuropathy leading to loss of visual function beginning with the peripheral visual field. One large population-based study found that individuals with visual impairment reported difficulties in performing most vision-dependent daily activities, including difficulty with driving. The objective of this retrospective cohort study was to investigate the driving habits of glaucoma patients and to determine the conformance of their visual acuity and visual fields with driving regulations. METHODS: The charts of 20 patients followed in the Ophthalmology Department of Foch Hospital, Suresnes, Paris, France, with open angle glaucoma (mean visual field mean deviation of the worse eye: -15.5 dB; range -1.97 to -27 dB) and still driving, were reviewed. Data collected included visual acuity, type of glaucoma, slit lamp and fundus examination, most recent standard automated perimetry, and binocular visual field test results. Each patient was asked if he or she still drove on highways, and if he or she still drove at night. RESULTS: The driving habits of glaucoma patients were analyzed, and visual acuity and binocular visual fields were compared to French and European legal driving criteria. Thirteen patients (65%) with glaucoma were still driving on highways, and five (25%) at night. Seven patients (35%) were below French legal minimum visual acuity or visual field criteria. CONCLUSION: Glaucoma patients appear to self-regulate their driving habits by avoiding potentially difficult driving situations. Further studies with larger sample size are necessary to determine relationships between severity of visual impairment, severity of visual field defects, and the cessation of driving.

[Role of embolization in the management of uterine fibroids]. / Place de l'embolisation dans le traitement des fibromes.

Uterine artery embolization using non spherical PVA particles or calibrated trisacryl microspheres above 500 µm is effective to treat menorrhagia, bulk-related symptoms and pelvic pain in more than 90% of cases in the short-term. In the long-term, embolization is effective in 75% of cases at 5-7 years. At 6 months, uterine volume reduction and dominant fibroid volume reduction varies between 30-60% and 50-80% respectively. During hospital stay, the complication rate is 3%. Secondary hysterectomy for complication is less than 2% at 3 months. Definitive amenorrhea is reported in less than 5% of cases in women of less than 45 years of age. No significant impact of embolization on hormonal function has been reported in women less than 45 years with normal baseline function. Secondary hysterectomy for clinical failure or recurrence is reported in 14-28% of cases at 5 years. Non-spherical PVA particles are associated with more microcatheter occlusion than trisacryl microspheres. No difference between PVA particles and trisacryl microspheres was found in terms of post-embolization pain or analgesic doses. PVA microspheres (Contour SE et Bead Block) are associated with lower clinical success and lower fibroid devascularization using MRI than trisacryl microspheres. No difference between PVA particles and trisacryl microspheres was found in terms of clinical efficacy, uterine volume reduction and complication rate. Randomized studies comparing embolization to hysterectomy demonstrate that reinterventions are more frequently performed after embolization. Secondary hysterectomy is performed in 13 to 24% of cases at 2 years and in up to 28% of cases at 5 years. Hospital stay, duration of recovery and time off work are shorter after embolization compared to hysterectomy. Embolization is cheaper than hysterectomy at 12 and 24 months even taking into consideration the additional costs of imaging and reinterventions. Randomized studies comparing embolization to myomectomy demonstrate that in the short- and mid-term there is no difference in terms of control of menorrhagia and bulk-related symptoms. Uterine volume reduction and quality of life were not different at 6 months. Periprocedural and 30-day complication rates are not different. At 6 months, the rate of complications is higher after myomectomy. Reinterventions are more frequent after embolization compared to myomectomy. Hospital stay, duration of recovery and time off work are shorter after embolization compared to myomectomy. Embolization should be considered with caution in pregnancy-seeking women since there is still a lack of good quality data available in the specific group of patients. FSH level is more frequently elevated after embolization compared to myomectomy. Pregnancy rate and term pregnancy rate are higher after myomectomy compared to embolization. Spontaneous abortion is more frequent after embolization than after myomectomy. There is no difference between embolization and myomectomy for the rates of pre-term delivery, cesarean section, post-partum hemorrhage, pre-eclampsia or intra-uterine growth retardation. Embolization performed before myomectomy (preoperative or combined procedures) can be discussed for an individual patient but there is not enough data to support its routine use.

[Assisted Reproductive Technologies in HIV patients: a comprehensive review of indications, techniques and results]. / Assistance médicale à la procréation et VIH: revue des indications, techniques et résultats.

Assisted Reproductive Technologies (ART) are authorized in France in couples infected by the human immunodeficiency virus (HIV) since the French legislation of May 10th, 2001. The goals are to reduce the risk of viral transmission between partners and to treat an underlying infertility. The classical techniques are used: IUI, IVF or ICSI, but all of them must be done in specifically authorized laboratories. ART outcome is favourable when only the man is infected, but seems to be less favourable when the woman is infected. Management of pregnancy planning should first propose to women infected by HIV, self inseminations when possible, and if needed, a quick ART treatment as some studies showed ovarian function alterations in HIV women. When the man is infected, IUI would be first proposed. Thousands of HIV positive male partners have used ART in Europe and no contamination has been reported so far. Approximately half of couples with one or both partners infected can hope to have a child through the ART process.

Ocular artery thrombosis as an initial presentation of a prothrombin G20210A mutation.

The G20210A mutation in the prothrombin gene is an established risk factor for venous thrombosis. There is controversy as to the role played by this mutation in arterial thrombotic disease. We present the case of a 56-year-old man who presented with a central retinal artery occlusion of the left eye. Evaluation revealed hypercholesterolemia, smoking, and heterozygosity for the prothrombin G20210A mutation. The literature concerning hereditary thrombophilia and retinal artery occlusion was reviewed. The synergistic effect of multiple risk factors is emphasized. Screening for hereditary thrombophilia should be considered, regardless of patient age. The prothrombin G20210A mutation may be associated with central retinal artery occlusion.

Feasibility of ovarian cryopreservation in borderline ovarian tumours.

BACKGROUND: Borderline ovarian tumours (BOT) do not exhibit overt stromal invasion and are less aggressive than invasive epithelial ovarian tumours. BOT also arise in younger patients than those who develop epithelial ovarian tumours. Our aim was to evaluate the feasibility of ovarian cryopreservation (OC) in patients treated for BOT. METHODS: A retrospective study of data concerning young patients (less than 35 years of age) who underwent surgery for a BOT with OC planned during the surgical procedure. RESULTS: Twenty-three patients, treated between January 2002 and February 2008, were initially selected but six of them were excluded from the present study (four because the tumour was malignant and two because it was benign). Finally, 17 patients were diagnosed as having BOT based on the frozen section analysis. In nine (53%) of these cases, OC was finally performed. In eight cases, OC was not performed; instead, in four cases a simple cystectomy was finally performed (one patient was in fact pregnant at the time of surgery), in one case malignant disease was found and in three (18%) patients OC was not technically feasible because no normal ovarian parenchyma was evident on gross inspection. CONCLUSION: In patients treated for a BOT, OC was eventually feasible in 53% of patients in whom this procedure was initially planned. In 18%, this procedure was aborted because no macroscopic healthy ovarian tissue could be found.

[Inadvertent intravitreal lidocaine injection following subcutaneous palpebral anesthesia: retinal toxicity of lidocaine?]. / Injection intravitréenne accidentelle de lidocaïne au cours d'une anesthésie palpébrale: toxicité rétinienne de la lidocaïne?

INTRODUCTION: We report an atypical case of scleral perforation due to an inadvertent intravitreal lidocaine injection following palpebral anesthesia. We discuss the management of this rare complication and focus on the transient lidocaine toxicity on human retina. OBSERVATION: A 29-year-old man presented with unilateral decreased vision during a lower right palpebral anesthetic injection for a chalazion removal procedure. The patient's vision was light perception. Examination revealed intraocular pressure at 55 mmHg, a wound of the posterior crystalloid, an intraocular gas bubble, and a central retinal artery spasm. On ERG, the b wave was decreased. The central retinal artery spasm resolved with prompt reduction of hypertony. Twenty-four hours later, the vision was 6/10 and the ERG showed an increased b wave activity. No clinical retinal toxicity of lidocaine was observed. Only a subcapsular cataract was observed, which had caused the loss of vision. CONCLUSION: This case confirms that lidocaine is well tolerated by the retina and reminds us that superficial palpebral anesthetic injection should be done with great caution.

Comparison of optical coherence tomography models OCT1 and Stratus OCT for macular retinal thickness measurement.

AIMS: To compare the values measured for retinal macular thickness with the first and last generations of the optical coherence tomograph (OCT1 and Stratus OCT, Zeiss, Humphrey Division). METHODS: This was a cohort study. 59 eyes were examined: 17 had a normal macula and 42 had a diabetic macular oedema. In each eye, mean retinal thickness (RT) was measured automatically in the nine macular Early Treatment Diabetic Retinopathy Study areas and at the foveal centre, using OCT1 and Stratus OCT. The paired mean RT values for each area and the type and proportion of artefacts were compared. RESULTS: Of the 590 automatic measurements, 505 had no artefact, either with OCT1 or Stratus OCT. The mean difference between the OCT1 and Stratus OCT measurements was 25 (SD 26.2) microm (p<0.0001). With Stratus OCT, RT values were significantly higher, by 8.1% (7.8%), than with OCT1. Artefacts were only observed in cases of diabetic macular oedema and were significantly more frequent with OCT1 than Stratus OCT (10.5% versus 4.4, p<0.0001). CONCLUSION: The macular retinal thickness values measured with Stratus OCT were significantly higher than those measured with OCT1. Stratus OCT has the advantage of producing fewer artefacts than OCT1 in pathological cases.

[An atypical case of malignant hypertensive retinopathy in a young child]. / Présentation d'un cas atypique de rétinopathie hypertensive maligne chez une fillette.

Stage IV hypertensive retinopathies in children have been described, but their incidence appears to be rare. Most etiologies are nephropathies. The authors present a clinical case of malignant high blood pressure in a young girl whose ophthalmological tests detected an unusual nephropathy, the Ask-Upmark kidney, illustrating the importance of determining high blood pressure chronicity and using Kirkendall's classification. Systematic fluorescein angiography and NMR on atypical subjects prevents the diagnosis of Leber neuroretinis, the main differential diagnosis. Early treatment of high blood pressure can avoid complications such as macular exudes.

[Intramedullary spinal cord sarcoidosis. Case report and review of the literature]. / Neurosarcoïdose intramédullaire inaugurale d'une sarcoïdose systémique. A propos d'un cas et revue de la littérature.

Sarcoidosis is a multisystemic granulomatosis disease of unknown etiology which commonly involves hilary nodes and lungs. Involvement of the nervous system represents 5 to 15% of the cases. We report on a rare case of cervicothoracic spinal cord sarcoidosis in an African man and review the literature on the subject. His only symptoms were those of a subacute myelopathy. On MR-imaging, coexistence of abnormal signal of cervicothoracic spinal cord with mediastinal lymph nodes was suggestive of sarcoidosis, which was confirmed by bronchial biopsies making unnecessary biopsies of the spinal cord lesion. Under corticotherapy both symptoms and radiological abnormalities rapidly regressed. We emphasize the rarity of sarcoidosis exclusively revealed by a myelopathy. We stress the importance of searching other localizations which are easier and safer to biopsy than the spinal cord lesion itself and illustrate the MR appearances of the lesion which are suggestive, however not specific of the disease.

Infant temperament and the brainstem auditory evoked response in later childhood.

Brainstem auditory evoked responses (BAERs) were evaluated on 10-12-year-old children (N = 56) who had been classified as high or low reactive to unfamiliar stimuli at 4 months of age. BAER measurement was selected because high reactive infants tend to become inhibited or fearful young children, and adult introverts have a faster latency to wave V of the BAER than do extroverts. Children previously classified as high reactive at 4 months had larger wave V components than did low reactive children, a finding that possibly suggests greater excitability in projections to the inferior colliculus. The fact that a fundamental feature of brainstem activity differentiated preadolescent children belonging to two early temperamental groups supports the value of gathering physiological data in temperament research.

Using data to improve medical practice by measuring processes and outcomes of care.

BACKGROUND: The purpose of this article is to help clinicians expand their use of data to improve medical practice performance and to do improvement research. Clinical practices can be viewed as small, complex organizations (microsystems) that produce services for specific patient populations. These services can be greatly improved by embedding measurement into the flow of daily work in the practice. WHY DO IT?: Four good reasons to build measures into daily medical practice are to (1) diagnose strengths and weaknesses in practice performance; (2) improve and innovate in providing care and services using improvement research; (3) manage patients and the practice; and (4) evaluate changes in results over time. It is helpful to have a "physiological" model of a medical practice to analyze the practice, to manage it, and to improve it. One model views clinical practices as microsystems that are designed to generate desired health outcomes for specific subsets of patients and to use resources efficiently. This article provides case study examples to show what an office-based practice might look like if it were using front-line measurement to improve care and services most of the time and to conduct clinical improvement research some of the time. WHAT ARE THE PRINCIPLES FOR USING DATA TO IMPROVE PROCESSES AND OUTCOMES OF CARE?: Principles reflected in the case study examples--such as "Keep Measurement Simple. Think Big and Start Small" and "More Data Is Not Necessarily Better Data. Seek Usefulness, Not Perfection, in Your Measures"--may help guide the development of data to study and improve practice. HOW CAN A PRACTICE START TO USE DATA TO IMPROVE CARE AND CONDUCT IMPROVEMENT RESEARCH?: Practical challenges are involved in starting to use data for enhancing care and improvement research. To increase the odds for success, it would be wise to use a change management strategy to launch the startup plan. Other recommendations include "Establish a Sense of Urgency. (Survival Is Not Mandatory)" and "Create the Guiding Coalition. (A Small, Devoted Group of People Can Change the World)." SUMMARY: Over the long term, we must transform thousands of local practice cultures so that useful data are used every day in countless ways to assist clinicians, support staff, patients, families, and communities.

N-acetyl-L-tyrosine (NAT) as a substrate for mushroom tyrosinase.

N-acetyl tyrosine (NAT) is hydroxylated by mushroom tyrosinase and the N-acetyl dopa formed is oxidized by the enzyme to N-acetyl dopaquinone (lambda max = 390 +/- 10 nm). H2O2 and NH2OH each shortened the lag period of NAT hydroxylation by the enzyme. H2O2 had an effect on the changes with time in the spectrum of product(s) formed and on the spectrum of the final product(s) obtained when NAT was hydroxylated by mushroom tyrosinase, in a manner suggesting that H2O2 converts N-acetyl dopaquinone to a pink-violet product(s) (lambda max = 490 nm), whereas such a product(s) was not formed in the absence of H2O2. A pink-violet product(s) (lambda max 490 +/- 20 nm) was also formed when NAT was hydroxylated by mushroom tyrosinase in the presence of NH2OH or para amino benzoic acid (PABA), probably as a result of an interaction between N-acetyl dopaquinone and NH2OH or PABA forming mono- or di-oximes. Kojic acid (5-hydroxy-2-hydroxymethyl)-4H-pyran-4-one) inhibited effectively the rate of NAT hydroxylation by mushroom tyrosinase in the absence or presence of H2O2. When NAT was oxidized by the enzyme in the absence of kojic acid, N-acetyl dopaquinone was formed at once and a shoulder at 490-530 nm appeared later. Under identical conditions but in the presence of kojic acid, a yellow product(s), characterized by a peak at 320 +/- 10 nm, was detected, suggesting that N-acetyl dopaquinone oxidizes kojic acid to the yellow product(s). Maltol (3-hydroxy-2-methyl-4H-pyran-4-one), a gamma-pyrone derivative structurally related to kojic acid, also inhibited the rate of NAT hydroxylation by mushroom tyrosinase. The addition of maltol at the plateau phase of the reaction resulted in an immediate decline in absorbance at 400 nm, suggesting that maltol conjugates with N-acetyl dopaquinone, yielding a product(s) characterized by a lower extinction coefficient at 400 nm than that of N-acetyl dopaquinone alone. The final brown-red product(s) formed when NAT was hydroxylated by mushroom tyrosinase was bleached in the presence of ascorbic acid or H2O2.

Effect of maltol on the oxidation of DL-DOPA, dopamine, N-acetyldopamine (NADA), and norepinephrine by mushroom tyrosinase.

Maltol (3-hydroxy-2-methyl-4H-pyran-4-one) appears to inhibit the rate of oxidation of DL-DOPA, dopamine, NADA and epinephrine by tyrosinase when assayed spectrophotometrically but not when assayed polarographically. Maltol has an effect on the spectrum of product(s) formed when each catecholamine was oxidized by tyrosinase showing that maltol hastens the disappearance of the quinones, possibly by conjugating with them. Indeed, at relatively high concentrations, maltol prevented the conversion of DL-DOPA, dopamine, and norepinephrine to their corresponding melanins via tyrosinase.

Effect of kojic acid on the oxidation of DL-DOPA, norepinephrine, and dopamine by mushroom tyrosinase.

Kojic acid inhibits effectively the rate of formation of pigmented product(s) and of oxygen uptake when DL-DOPA, norepinephrine and dopamine are oxidized by mushroom tyrosinase. In addition to the direct effect of kojic acid on the enzyme, kojic acid also affects the UV-VIS spectrum of the final product(s) formed, this being due to the ability of the o-quinones of these substrates to oxidize kojic acid to a yellow product(s). Kojic acid can thus prevent the conversion of the o-quinones of DL-DOPA, norepinephrine and dopamine to their corresponding melanin.

Effect of different isomers of dihydroxybenzoic acids (DBA) on the rate of DL-dopa oxidation by mushroom tyrosinase.

Dihydroxybenzoic acids (DBA), such as 3,4-DBA, 3,5-DBA, and 2,4-DBA--at all concentrations tested--inhibited the rate of DL-DOPA oxidation to dopachrome (lambda max = 475 nm) by mushroom tyro0sinase. 2,3-DBA and 2,5-DBA at relatively low concentration had a synergistic effect on the reaction, whereas at relatively high concentrations they inhibited the rate of DL-DOPA oxidation. The synergistic effect of 0.6-13.3 mM 2,3-DBA on the rate of DL-DOPA oxidation to dopachrome (lambda max = 475 nm) was found to be due to the ability of 2,3-DBA-o-quinone (formed by the oxidation of 2,3-DBA by mushroom tyrosinase or by sodium periodate) to oxidize DL-DOPA to dopachrome (via dopaquinone) non-enzymatically. A similar explanation is likely to be valid for the synergism exerted by 2,5-DBA on the rate of DL-DOPA oxidation by mushroom tyrosinase.