Proton damage in (Y,Lu,Gd)3(Al,Ga)5O12:Ce mixed garnet scintillators

Scintillators are vital components for nuclear instrumentation and its applications, including plasma diagnostics and imaging. As yields in controlled fusion experiments increase, the radiation tolerance of scintillator candidates for use in instrumentation is of particular importance. High radiation exposure can damage scintillating materials and alter the optical properties. The effects of radiation damage in Ce-doped mixed garnet ceramics over the compositional range (Y,Gd,Lu)₃(Al,Ga)₅O₁₂ are investigated using optical techniques. The samples were exposed to 200 keV protons to an accumulated fluence of 10¹⁶ protons per square centimeter, then characterized using diffuse reflectance spectroscopy (DRS). DRS with visible light can assess the radiation tolerance of opaque poly-crystalline samples, which can be easily sintered from powders and thus offer distinct advantages in characterization compared to single crystals. Qualitative trends in induced absorption are presented as a function of composition, and the ideal cerium dopant concentration for Y₂LuAl₅O₁₂ is determined to be 0.60-0.75 mol. %.

Brain sex differences and hormone influences: a moving experience?

Sex differences in the nervous system come in many forms. Although a majority of sexually dimorphic characteristics in the brain have been described in older animals, mechanisms that determine sexually differentiated brain characteristics often operate during critical perinatal periods. Both genetic and hormonal factors likely contribute to physiological mechanisms in development to generate the ontogeny of sexual dimorphisms in brain. Relevant mechanisms may include neurogenesis, cell migration, cell differentiation, cell death, axon guidance and synaptogenesis. On a molecular level, there are several ways to categorize factors that drive brain development. These range from the actions of transcription factors in cell nuclei that regulate the expression of genes that control cell development and differentiation, to effector molecules that directly contribute to signalling from one cell to another. In addition, several peptides or proteins in these and other categories might be referred to as 'biomarkers' of sexual differentiation with undetermined functions in development or adulthood. Although a majority of sex differences are revealed as a direct consequence of hormone actions, some may only be revealed after genetic or environmental disruption. Sex differences in cell positions in the developing hypothalamus, and steroid hormone influences on cell movements in vitro, suggest that cell migration may be one target for early molecular actions that impact brain development and sexual differentiation.

Infective keratitis in older patients: a 4 year review, 1998-2002

BACKGROUND/AIM

There are few clinical series in the literature of infective keratitis in the elderly, even though this age group constitutes a significant proportion of those affected by this condition. The authors aimed to determine the incidence and risk factors for infective keratitis in those over 60 years, the causative organisms, antibiotic susceptibilities, visual and tectonic outcome, and surgical intervention rate.

METHODS

A retrospective review of all patients aged 60 years and over admitted to the Sydney Eye Hospital with a diagnosis of infective keratitis, between September 1998 and December 2002.

RESULTS

190 patients were identified with a mean age of 75.5 (SD 9.6) years (range 60-101). Local risk factors were found in 93.7%, and systemic risk factors in 27.9%. Organisms were cultured in 62.8%, and 7.9% had positive herpes simplex virus (HSV) polymerase chain reaction (PCR). Perforation or severe thinning occurred in 36% overall, but in 80% with positive HSV PCR. Acute surgical intervention was required in 43.7%, with acute penetrating keratoplasty performed in 17.9%, and 8.9% required evisceration. Mean presenting visual acuity was 1.82 (SD 1.24), equivalent to 6/300, excluding 26.3% with vision of light perception (LP) or worse. Mean final visual acuity was 1.24 (SD 1.16), equivalent to 6/100, excluding 19.5% with vision of LP or worse (p<0.0005).

CONCLUSIONS

The elderly represent a distinct clinical group in the context of microbial keratitis. Predisposing factors are very common, they present with poor vision, have a high complication and surgical intervention rate, and a poor visual outcome compared to younger patients. The microbiological spectrum is similar to younger age groups, except that HSV is more common and may increase the risk of severe corneal thinning and perforation. Most bacterial isolates remain sensitive to currently available antibiotic preparations.

Penetrating keratoplasty in children: visual and graft outcome

AIMS

To review factors affecting graft survival and determinants of visual acuity after penetrating keratoplasty in children.

METHODS

All cases of penetrating keratoplasty performed in an ophthalmic unit, in children aged less than 15 years at the time of operation, for the period 1984 to 2002 were included.

RESULTS

19 penetrating keratoplasties were done in 18 eyes of 16 children, age range 2 weeks to 14 years 8 months (mean 9.24 years), with mean follow up 6.6 years. 73.7% of grafts have remained clear for up to 14 years. Postoperative visual acuity among congenital indications for graft was better than 6/60 in only 14.2% of cases, but was better than or equal to 6/12 in all cases of keratoconus.

CONCLUSION

This series shows that prolonged corneal graft survival can be achieved in children, but successful restoration of visual acuity depends upon a period of normal visual development before the onset of corneal opacification.

Resistance of Acanthamoeba castellanii cysts to physical, chemical, and radiological conditions

Resistance of Acanthamoeba castellanii cysts to disinfection agents, antimicrobial agents, heat, freeze-thawing, ultraviolet radiation (UV), gamma irradiation, and cellulase were evaluated in vitro. Following exposure to different agents, the cysts were removed and cultured for A. castellanii trophozoites for 3-14 days. Solutions containing 20% isopropyl alcohol or 10% formalin effectively killed A. castellanii cysts. Hydrogen peroxide (3%, AOSept Disinfectant) effectively killed A. castellanii cysts after 4 hr of exposure. Polyhexamethylene biguanide (0.02%), clotrimazole (0.1%), or propamidine isethionate (Brolene) were effective in killing A. castellanii cysts in vitro. Acanthamoeba castellanii cysts were resistant to both 250 K rads of gamma irradiation and 800 mJ/cm2 of UV irradiation. Excystment of trophozoites was accelerated after exposure to 10, 100, and, 1,000 units of cellulase. These results suggest that A. castellanii cysts benefit by enhanced survival because of their resistance to very harsh environmental conditions.

Manidipine: a review of its use in hypertension

Manidipine is a dihydropyridine calcium antagonist, which causes systemic vasodilation by inhibiting the voltage-dependent calcium inward currents in smooth muscle cells. The resulting reduction in blood pressure (BP) in patients with hypertension is maintained over 24 hours. Manidipine 10 to 40 mg once daily for 4 weeks significantly lowered office BP from baseline and compared with placebo, and significantly reduced 24-hour BP compared with placebo in patients with essential hypertension in a well controlled trial. The decline in BP was maintained over 24 hours (trough to peak BP ratios were >50%) without disturbing the circadian BP pattern. BP reductions with therapeutic dosages of manidipine were maintained for up to 1 year in noncomparative trials. The BP-lowering capacity of manidipine 5 to 20 mg/day appears to be similar to that of other calcium antagonists with which it has been compared in randomised double-blind and nonblind trial. In a well controlled short term trial, manidipine 10 mg daily significantly decreased trough sitting BP compared with placebo in elderly patients with mild to moderate essential hypertension. Decreases in BP were maintained for up to 3 years of treatment. The drug (10 or 20 mglday) also significantly lowered sitting BP from baseline in patients with hypertension and type 2 diabetes mellitus in randomised, long term comparative trials. In general, the observed reduction in BP with manidipine was similar to that observed with amlodipine, enalapril or delapril. The effects of manidipine on urinary albumin excretion (UAE) have not been clearly demonstrated in clinical trials in this patient group. BP was also reduced with manidipine in patients with impaired glucose tolerance. Manidipine was well tolerated in clinical trials, with most adverse effects related to vasodilation. Commonly reported events included ankle oedema, headache. palpitation. flushing, dizziness, rash and fatigue. Manidipine appears to have less potential for pedal oedema than amlodipine.

CONCLUSIONS

Manidipine has shown antihypertensive efficacy and appears to be well tolerated in adult and elderly patients with mild or moderate essential hypertension. The BP-lowering effects of the drug in patients with hypertension and type 2 diabetes mellitus or impaired glucose tolerance were not associated with any adverse metabolic effects. The effects of manidipine on UAE in this patient group remain unclear. Manidipine provides an additional treatment option for patients for whom dihydropyridine calcium antagonists are appropriate. Manidipine is a dihydropyridine calcium antagonist, which causes systemic vasodilation by inhibiting the voltage-dependent calcium inward currents in smooth muscle cells. The resulting reduction in blood pressure (BP) in patients with hypertension is maintained over 24 hours. Manidipine 10 to 40mg once daily for 4 weeks significantly lowered office BP from baseline and compared with placebo, and significantly reduced 24-hour BP compared with placebo in patients with essential hypertension in a well controlled trial. The decline in BP was maintained over 24 hours (trough to peak BP ratios were >50%) without disturbing the circadian BP pattern. BP reductions with therapeutic dosages of manidipine were maintained for up to 1 year in non-comparative trials. The BP-lowering capacity of manidipine 5 to 20 mg/day appears to be similar to that of other calcium antagonists with which it has been compared in randomised double-blind and nonblind trial. In a well controlled short term trial, manidipine 10 mg daily significantly decreased trough sitting BP compared with placebo in elderly patients with mild to moderate essential hypertension. Decreases in BP were maintained for up to 3 years of treatment. The drug (10 or 20 mg/day) also significantly lowered sitting BP from baseline in patients with hypertension and type 2 diabetes mellitus in randomised, long term comparative trials. In general, the observed reduction in BP with manidipine was similar to that observed with amlodipine, enalapril or delapril. The effects of manidipine on urinary albumin excretion (UAE) have not been clearly demonstrated in clinical trials in this patient group. BP was also reduced with manidipine in patients with impaired glucose tolerance. Manidipine was well tolerated in clinical trials, with most adverse effects related to vasodilation. Commonly reported events included ankle oedema, headache. palpitation. flushing, dizziness, rash and fatigue. Manidipine appears to have less potential for pedal oedema than amlodipine.

CONCLUSIONS

Manidipine has shown antihypertensive efficacy and appears to be well tolerated in adult and elderly patients with mild or mo

Topical eflornithine

Eflornithine is a specific, irreversible inhibitor of the enzyme ornithine decarboxylase which is thought to slow hair growth by inhibiting this enzyme in hair follicles. Percutaneous absorption of eflornithine in women with unwanted facial hair (hirsutism) was < 1% when the 15% cream was applied twice daily to a shaved 50 cm2 area of skin under the chin. In clinical studies in women with excessive, unwanted facial hair, eflornithine 15% cream was superior to placebo in reducing hair growth, as demonstrated by objective and subjective methods, after 2 to 8 weeks' treatment. After 24 weeks' treatment, 58% of eflornithine and 34% of placebo recipients had at least some improvement in facial hirsutism (for the purposes of this analysis all patients not assessed at week 24 were considered to be worse or to have no improvement). In addition, 32 versus 8% of patients were judged to be successfully treated (at least marked improvement). Hair growth returned to pretreatment rates within 8 weeks of stopping treatment. Use of a self-assessment questionnaire to assess the effect of study treatment on 6 aspects of patient well-being showed that eflornithine reduced the mean level of overall discomfort and bother by 33 versus 15% in placebo recipients. Adverse events mostly affected the skin. Only burning/stinging/tingling was markedly more common with eflornithine than with placebo.

Reviparin: a review of its efficacy in the prevention and treatment of venous thromboembolism

Reviparin (reviparin sodium) is a low molecular weight heparin (LMWH) that catalyses the inactivation of factors Xa and IIa by binding to antithrombin, which ultimately leads to the inhibition of the clotting cascade. It is administered subcutaneously. Reviparin 7,000 to 12,600 anti-XaIU/day was found to be as effective as intravenous unfractionated heparin in preventing the clinical recurrence of acute deep vein thrombosis (DVT) and/or pulmonary embolism in 1 large randomised, multicentre trial (COLUMBUS) and was significantly more effective than intravenous unfractionated heparin in the prevention of recurrent venous thromboembolism in another large randomised, multicentre trial (CORTES). Reviparin has also been compared with unfractionated heparin in children with established DVT. However, the trial was under-powered and no conclusion could be made regarding comparative efficacy. As prophylaxis, reviparin 1,750 anti-XaIU once daily was as effective as unfractionated heparin 5,000IU twice daily in 1,311 patients undergoing abdominal surgery and, in a once daily dosage of 4,200 anti-XaIU, was as effective as subcutaneous enoxaparin sodium 40 mg/day or acenocoumarol in patients undergoing hip replacement surgery. Reviparin 1,750 anti-XaIU also effectively prevented DVT. compared with no treatment, in patients undergoing knee arthroscopy. It was also more effective than placebo in patients with brace immobilisation of the lower extremity. Reviparin was compared with 'standard care' in children with central venous lines. However, the trial was too small to make conclusions regarding its efficacy. Comparative data indicate that reviparin is at least as well tolerated as heparin and enoxaparin sodium. However, in a large (n = 1,279) trial there were significantly fewer major bleeding episodes in patients receiving reviparin than in patients given the oral anticoagulant acenocoumarol. The most commonly reported adverse events in therapeutic trials have been intraoperative blood loss and postoperative bleeding complications such as wound haematoma, bruising and injection site haemorrhage. Reviparin was also well tolerated in 2 studies in children aged < or = 16 years.

CONCLUSION

Reviparin has shown efficacy in the treatment of established DVT and in the prevention of postoperative DVT after moderate and high risk surgery and was as effective as enoxaparin sodium or acenocoumarol in patients undergoing hip replacement surgery. As an effective and well tolerated antithrombotic agent, reviparin is likely to assume a significant role in the treatment and prevention of DVT, as it appears to have a preferable tolerability profile to subcutaneous heparin after moderate risk surgery and is at least as effective as intravenous heparin in the treatment of established DVT.

Effect of steroids on Acanthamoeba cysts and trophozoites

PURPOSE

Topical steroids are frequently used to control corneal inflammation and uveitis or is administered after surgery, to prevent corneal graft rejection. This study was undertaken to determine whether steroids could affect the pathogenicity of Acanthamoeba castellanii.

METHODS

The effect of dexamethasone phosphate on excystment, proliferation, and encystment of trophozoites and cysts of A. castellanii was examined in vitro. Cytolysis capacity of steroid-treated Acanthamoeba was quantified by a spectrophotometric assay, and plasminogen activators were measured by a fibrinolysis assay. The influence of steroid treatment on corneal infection in a Chinese hamster model of Acanthamoeba keratitis was examined in vivo.

RESULTS

Treatment of Acanthamoeba cysts with dexamethasone induced 4- to 10-fold increases in the number of trophozoites compared with untreated control cultures. Acceleration of trophozoite proliferation was observed when trophozoites were treated with dexamethasone. However, dexamethasone treatment did not affect encystment of Acanthamoeba trophozoites. Dexamethasone-treated trophozoites or cysts induced a significant cytopathic effect on corneal epithelial cells compared with untreated organisms. Supernatants collected from either dexamethasone-treated or untreated organisms failed to lyse corneal epithelial cells. Treatment of organisms with dexamethasone had no effect on production of plasminogen activators by Acanthamoeba trophozoites. Intramuscular injection of dexamethasone had a profound effect on the incidence, severity, and chronicity of keratitis. Keratitis in dexamethasone-treated hamsters was significantly more severe at all time points than in untreated animals (P < 0.05).

CONCLUSIONS

These findings indicate that exposure of Acanthamoeba trophozoites and cysts to dexamethasone increases the pathogenicity of the organisms. The results emphasize the importance of maintaining adequate amebicidal therapy if a topical steroid is used in the management of Acanthamoeba keratitis.

Perospirone

Perospirone is an atypical antipsychotic agent for the treatment of schizophrenia. Its primary mode of action is through antagonism of serotonin 5-HT2A and dopamine D2 receptors. An 8-week course of oral perospirone 8 to 48 mg/day displayed efficacy in up to 75% of patients with schizophrenia participating in phase II and phase III trials. The onset of action of the drug was about 2 weeks. Perospirone was effective against positive, negative and general symptoms in patients with schizophrenia, as assessed with standard rating scales (Brief Psychiatric Rating Scale, Positive and Negative Symptom Scale). Compared with haloperidol 2 to 12 mg/day, perospirone 8 to 48 mg/day was significantly more effective against negative symptoms and tended to be more effective against general symptoms and most positive symptoms in a trial in 145 patients with schizophrenia. Perospirone had efficacy similar to that of mosapramine 50 to 300 mg/day in a comparative phase III trial in 159 patients. Extrapyramidal symptoms (EPS) tended to occur less often and were generally milder with perospirone than with haloperidol or mosapramine.

Methylphenidate (OROS formulation)

Methylphenidate is a CNS stimulant that is thought to block the reuptake of dopamine and noradrenaline (norepinephrine) into the presynaptic neuron. A sustained release (OROS formulation of the drug has been developed for use in children with attention deficit/hyperactivity disorder (ADHD). In children aged 6 to 12 years with ADHD, the maximum plasma concentration of OROS methylphenidate 18 to 54 mg was reached after approximately 7 to 8 hours. In adults, the plasma concentration-time profile of OROS methylphenidate differed markedly from that of the sustained release and immediate release (IR) methylphenidate formulations. In a clinical trial involving 282 children with ADHD, once daily OROS methylphenidate 18 to 54 mg was significantly more effective than placebo and demonstrated an effect similar to IR methylphenidate 5 to 15 mg 3 times daily in reducing the symptoms of ADHD. OROS methylphenidate demonstrated sustained efficacy in a 1-year noncomparative study involving children with ADHD. In clinical trials, the OROS formulation of methylphenidate had a tolerability profile similar to that of IR methylphenidate.

Desloratadine

Desloratadine is the orally active major metabolite of the nonsedating H1-antihistamine loratadine. The drug had no adverse cardiovascular effects in various animal models or when administered at 9 times the recommended adult dosage for 10 days in volunteers. Therapeutic dosages had no effects on wakefulness or psychomotor performance in healthy volunteers. No clinically significant interactions have been reported between desloratadine and drugs that inhibit the cytochrome P450 system, nor does the drug potentiate the adverse psychomotor effects of alcohol. Oral desloratadine 5 mg once daily for up to 4 weeks in patients with seasonal allergic rhinitis (SAR) significantly reduced nasal (including congestion) and non-nasal symptoms and improved health-related quality of life compared with placebo. Similar beneficial effects were observed in patients with SAR and coexisting asthma (in whom asthma symptoms and use of beta2-agonists were reduced). Desloratadine 5 mg once daily for 6 weeks significantly improved pruritus and reduced the number of hives compared with placebo in patients with chronic idiopathic urticaria (CIU). Sleep and daytime performance also improved. Desloratadine was well tolerated in clinical trials and had an adverse event profile similar to that of placebo in patients with SAR (with or without asthma) or CIU.

Topiramate: a review of its use in childhood epilepsy

Topiramate is an antiepileptic drug (AED) which appears to have a broad range of antiseizure activity in humans. A previous overview focused primarily on results of trials of topiramate in adults with epilepsy, and this review highlights the use of topiramate in children. Clinical trials have shown that topiramate is effective when used adjunctively in children with refractory partial-onset seizures and generalised tonic-clonic seizures. The drug significantly reduced seizure frequency compared with placebo in children with partial-onset epilepsy after 16 weeks of double-blind adjunctive treatment (33.1 vs 10.5%); the frequency of secondarily generalised seizures was also markedly reduced. During a nonblind extension of this trial, the mean dosage was titrated from 4.8 to 9 mg/kg/day and further reductions in the frequency of seizures were observed (71% compared with prestudy levels). In 2 mixed adult/paediatric populations with primary generalised tonic-clonic seizures, topiramate (target dosage 5.2 to 9.3 mg/kg/day) reduced the seizure rate compared with those receiving placebo. This difference was significant in one trial (56.7 vs 9%) but not in another (57.1 vs 33.2%). A subanalysis of the paediatric patients found that the favourable effect of topiramate on seizure rates was not age-related. Topiramate (median average dosage 5.1 mg/kg/day) was also found to be useful as adjunctive therapy in the management of Lennox-Gastaut syndrome and significantly reduced the mean frequency of drop attacks by 14.8% compared with an increase of 5.1% with placebo. Further gains in seizure control were made in a nonblind extension of this trial where the mean topiramate dosage was 10 mg/kg/day. Nine of 11 patients in 1 pilot trial of children with otherwise intractable West syndrome, and 5 of 10 in another, achieved a > or =50% reduction in seizure rate with topiramate (target dosage up to 24 mg/kg/day). In an 18-month extension of the former trial (mean dosage 29 mg/kg/day) a > or =50% reduction in seizures was maintained in 7 of 11 children. Adverse events associated with adjunctive topiramate therapy in children were predominantly neuropsychiatric and generally mild to moderate in severity. Behavioural and cognitive problems do occur and are a limiting factor in some children. Also, weight loss can be problematical in some individuals. Withdrawal rates were low in the controlled trials (4.8%), but appear to be more frequent in noncomparative and post-marketing studies.

CONCLUSION

Well controlled studies have demonstrated that topiramate is an effective agent for the adjunctive therapy of partial and generalised tonic-clonic seizures in children. Treatment-limiting adverse events do occur, but these may be managed by slow titration. Although comparative studies with the other newer AEDs used in adjuntive therapy are required, topiramate is an important extension to the range of drugs that may be used to treat refractory epilepsy in children.

Oseltamivir: a review of its use in influenza

Oseltamivir is a prodrug of oseltamivir carboxylate (Ro 64-0802, GS4071), a potent and selective inhibitor of the neuraminidase glycoprotein essential for replication of influenza A and B viruses. Studies in volunteers with experimental human influenza A or B showed that administration of oral oseltamivir 20 to 200 mg twice daily for 5 days reduced both the quantity and duration of viral shedding compared with placebo. Subsequent assessment of the drug at a dosage of 75 mg twice daily for 5 days in otherwise healthy adults with naturally acquired febrile influenza showed that oseltamivir reduced the duration of the disease by up to 1.5 days and the severity of illness by up to 38% compared with placebo when initiated within 36 hours of symptom onset (earlier initiation of therapy was associated with faster resolution). The incidence of secondary complications and the use of antibacterials were also reduced significantly in oseltamivir recipients. A liquid formulation of oseltamivir (2 mg/kg twice daily for 5 days) has been shown to be effective in the treatment of children with influenza, and data presented in abstracts suggest that the drug may also be of use in high-risk populations such as the elderly or those with chronic cardiac or respiratory disease. In addition to treatment efficacy, the drug has demonstrated efficacy when used for seasonal or household prophylaxis. Oral oseltamivir (75 mg once or twice daily for 6 weeks) during a period of local influenza activity significantly prevented the development of naturally acquired influenza by >70% compared with placebo in unvaccinated otherwise healthy adults. The drug also demonstrated efficacy when used adjunctively in previously vaccinated high-risk elderly patients (92% protective efficacy). Short term administration of oseltamivir (75 mg once daily for 7 days) may significantly reduce the risk of illness in household contacts of infected persons when administered within 48 hours of symptom onset in the infected person. Oseltamivir 75 mg twice daily for 5 days was well tolerated in clinical trials in healthy adults and high-risk patients, with nausea and vomiting being the most commonly reported events. Gastrointestinal events were mild and transient and both nausea and vomiting were less likely when oseltamivir was taken with food.

CONCLUSIONS

Oseltamivir is a well tolerated orally active neuraminidase inhibitor which significantly reduces the duration of symptomatic illness and hastens the return to normal levels of activity when initiated promptly in patients with naturally acquired influenza. It therefore represents a useful therapeutic alternative to zanamivir (especially in patients who prefer oral administration or who have an underlying respiratory disorder) and the M2 inhibitors amantadine and rimantadine (because of its broader spectrum of anti-influenza activity and lower likelihood of resistance) in patients with influenza. In addition, although annual vaccination remains the best means of influenza prevention, there may be a place for oseltamivir in providing household prophylaxis or adjunctive prophylaxis in high-risk vaccinated patients during an outbreak of the disease or for use in patients in whom vaccination is unsuitable or ineffective.

Topical dorzolamide 2%/timolol 0.5%: a review of its use in the treatment of open-angle glaucoma

The nonselective beta-blocker timolol and the carbonic anhydrase inhibitor dorzolamide both lower intraocular pressure (IOP). Timolol and dorzolamide have different mechanisms of action and their effects are additive when administered together. Therefore, the 2 drugs are frequently used concomitantly to treat patients with open-angle glaucoma who have not adequately responded to first-line therapy. A barrier to good compliance with concomitant therapy is the need to administer 5 or 6 drops of medication on 2 or 4 occasions during the day. Timolol 0.5% and dorzolamide 2.0% have therefore been combined in a single formulation, reducing the number of administrations required to 2 per day. Clinical trials in patients with glaucoma have demonstrated that dorzolamide 2%/timolol 0.5% (dorzolamide/timolol) is superior to monotherapy with the individual components. When dorzolamide/timolol administered twice daily was compared with concomitant treatment with dorzolamide 2% and timolol 0.5%, each administered twice daily for 90 days, both regimens resulted in marked lowering of trough IOP (measured just before the morning dose) compared with baseline (reduction in IOP = 4.2mm Hg). The effect of the 2 regimens on IOP at all time points, both before treatment and at peak effect (2 hours after treatment), were virtually indistinguishable. When the combined formulation was compared with a concomitant regimen that included dorzolamide 2% 3 times daily and timolol 0.5% twice daily the concomitant regimen was slightly more efficacious than the combined regimen at trough after 90 days: IOP was lowered by 3.6mm Hg in the combined group versus 4.1 mm Hg in the concomitant group. Dorzolamide/timolol has been compared with concomitant administration of timolol 0.5% and the IOP lowering miotic drug, pilocarpine 2.0%. This non-blind patient-preference study found that both regimens reduced IOP. However, the dorzolamide/timolol combination was preferred by the patients because of reduced frequency and severity of adverse effects and less frequent administration. Dorzolamide/timolol was well tolerated in clinical trials, the adverse effects reflected those of the individual components, and no additional tolerability issues were identified. However, the potential for timolol to cause cardiorespiratory effects must be considered when prescribing this combination. Furthermore, dorzolamide is a sulfonamide and can cause allergic reactions in those who are hypersensitive to this class of drug.

CONCLUSIONS

Dorzolamide/timolol is a well tolerated and effective fixed combination for lowering IOP in the treatment of open-angle glaucoma and is likely to be useful in those patients who do not respond adequately to first-line monotherapy. Compared with concomitant therapy with the same 2 drugs the primary advantage is convenience, which may lead to improved compliance. Studies of compliance and comparisons with other currently available combination therapies would be useful to fully define the value of the formulation. Nonetheless, dorzolamide combined with timolol in a single applicator system will be a useful addition to the treatment options for glaucoma, a leading cause of preventable blindness.

Squamous cell carcinoma with necrotizing scleritis

PURPOSE

To report on a case of limbal squamous cell carcinoma (SCC) with necrotizing scleritis in a young, previously healthy, white Australian male.

METHODS

A 31-year-old man presented with a left limbal lesion intermittently causing a red eye and foreign body sensation. He had enjoyed surfing for many years. Repeat HIV tests were negative and the lesion was biopsied.

RESULTS

Biopsy showed a well-differentiated SCC apparently arising in an intra-epithelial (in situ) carcinoma of the conjunctiva. The lesion was excised and a corneoscleral graft repair was performed.

CONCLUSION

The present case highlights the potential for a significant increase in the prevalence of ocular surface neoplasia in healthy young people who have had excessive UV-B exposure.

Sudden loss of vision

BACKGROUND

Sudden loss of vision is an ophthalmological emergency.

OBJECTIVE

This article explains how history and examination, particularly ophthalmoscopy, will greatly assist the general practitioner to diagnose the cause.

DISCUSSION

Vision loss may be transient or prolonged. It is important to consider whether the eye is painful or comfortable, inflamed or not. An accurate diagnosis will direct the emergency management, which frequently determines the prognosis for vision.

Suppurative corneal ulceration in Bangladesh. A study of 142 cases examining the microbiological diagnosis, clinical and epidemiological features of bacterial and fungal keratitis

Suppurative keratitis is an important preventable cause of blindness, particularly in the developing world. This study analyses 142 cases of suppurative keratitis referred to Chittagong Eye Infirmary Bangladesh. Some 53.5% of cases were bacterial and 35.9% were fungal. The five most common pathogens were: Pseudomonas sp. 24%, Streptococcus pneumoniae 17%, Aspergillus sp. 13%, Fusarium sp. 7% and Curvularia sp. 6%. Gram stain and culture results were consistent in 62.6% of cases. Previous antibiotic treatment was a significant factor for failure of culture isolation and less so for Gram stain failure. On Gram stain, 55.9% of pseudomonal cases were missed, but only 2% of fungal cases were missed. Over all, Gram stain had a sensitivity of 62% and positive predictive value of 84% for bacterial cases, and 98% and 94% for fungal cases, respectively. Fungal ulcers were typically filamentous, but an antecedent history of trauma was not common. The most frequent injury was due to rice grains, but the inoculum appeared to be introduced during eye washing with contaminated water. Pseudomonal ulcers occurred most frequently in the monsoon season, and Fusarium cases were seen only in the hot, dry season.

Spontaneous visual improvement in the presence of posterior capsule opacification

We report a case of a patient who had reduced visual acuity due to posterior capsular opacification after extracapsular cataract extraction and posterior chamber lens implantation. Capsulotomy was not performed. Over the subsequent two years visual acuity returned spontaneously to normal.

Suppurative keratitis in rural Bangladesh: the value of gram stain in planning management

External eye disease which result in corneal scarring are an important cause of blindness in Bangladesh and at the Chittagong Eye Infirmary and Training Complex (EITC) over 200 cases of suppurative keratitis are managed each year. We reviewed the records of 127 cases of microbial keratitis to determine the relative contributions of Gram stain and culture to diagnosis of the causative organism. There were 107 culture-proven cases of microbial keratitis amongst the 127 patients in this study. Gram stain was positive in 89 cases which represents 70% of the total and 83% of all culture-proven cases. Streptococcus pneumoniae and Pseudomonas sp were the commonest bacteria isolated and Aspergillus sp and Fusarium sp the commonest fungi. In 20 cases (16%) no organism was isolated on Gram stain or culture. Our results support the use of both Gram stain and culture in isolation of the causative organism in cases of suppurative keratitis in Bangladesh. However the low cost of Gram stain and its useful recovery rates for both bacteria and fungi support its use as an initial investigation for microbial keratitis at the secondary level of eye care in rural Bangladesh.

Acanthamoebic keratitis diagnosed by paracentesis and biopsy and treated with propamidine

A previously healthy 53-year-old man had keratitis of the right eye for six months, unresponsive to topical medical therapy. Acanthamoeba was grown from tissue obtained by corneal biopsy and from aqueous from an anterior chamber tap. The patient was treated with propamidine isethionate 0.1% drops and dibromopropamidine isethionate 0.15% ointment, and after two and a half months the ocular inflammation was continuing to resolve. This case supports a role for the diamidines in the treatment of acanthamoebic keratitis.

Microbiological diagnosis of suppurative keratitis in Bangladesh

Experience in setting up an inexpensive microbiology laboratory in the Bangladesh National Society for the Blind Eye Hospital and Training Complex at Chittagong is presented, together with the results of a pilot study to identify organisms responsible in 33 consecutive cases of suppurative keratitis in the Chittagong area of Bangladesh. Of the 33 cases 21 were positively identified by means of Gram stain and/or culture. Two-thirds of the responsible organisms were bacteria, and one-third were fungi. The bacterial causes included Streptococcus pneumoniae and Pseudomonas aeruginosa. The fungi isolated were Aspergillus fumigatus, Aspergillus ochraceus, and Fusarium solani. Among the causes of failure to diagnose the organism was chronicity of infection and previous treatment. The value of the study in the planning of future treatment regimens, and the implications of setting up similar relatively cheap microbiology laboratory facilities in developing countries, are discussed.

Endophthalmitis following cataract extraction

We describe a case of bacterial endophthalmitis complicating routine cataract extraction and intraocular lens implantation in a 91-year-old woman. The ocular and systemic factors that may have predisposed to intraocular infection in this case, and the possibility of predicting these pre-operatively, are discussed.

Concurrent pineoblastoma and unilateral retinoblastoma: a forme fruste of trilateral retinoblastoma?

A 10-month-old boy who presented with strabismus and symptoms of intracranial hypertension was found to have a pineoblastoma and a unilateral ocular retinoblastoma. Despite enucleation of the eye, subtotal removal of the pineoblastoma, and craniospinal axis irradiation, the patient died 6 months later from disseminated intracranial neoplasm. As there was no clinical evidence of bilateral retinoblastoma, this case may represent a forme fruste of the trilateral retinoblastoma complex. The clinicopathological features of this unusual syndrome are reviewed.

Anemia of prematurity: determinants of the erythropoietin response

This study was undertaken to determine the factors that are important in determining the erythropoietin response in low-birth-weight infants during the period of so-called anemia of prematurity. In the first weeks of life oxygen consumption in a group of 21 infants gradually increased as hemoglobin level fell. The magnitude of the erythropoietin response inversely varied with the central venous oxygen tension (P-vO2) (r = -0.55, P less than 0.001). When the P-vO2 declined to less than 30 torr, erythropoietin values were uniformly increased above the "normal" range (defined as the values associated with P-vO2 greater than 38 torr). Erythropoietin values varied inversely with hemoglobin but in general did not exceed the values observed for normal adult men. The erythropoietin values in the infants were remarkably lower at any given hemoglobin level when compared with those of older children with anemia resulting from bone marrow failure. In general, elevations of erythropoietin were seen when the hemoglobin concentration declined to less than 10.0 gm/dl. Change in heart rate did not appear to be a reliable indicator of the presence of anemia; rather, it correlated best with oxygen consumption.

Dextran 40-containing incubation media: effect on lens electrolyte and water balance

The effect of dextran 40 on lens swelling and electrolyte balance in lenses stressed by incubation in Ca++-free media was studied. Dextran 40 substantially inhibited lens swelling, Na+ gain, and K+ loss caused by six-hour incubation in Ca++-free media. After an additional 12-hour incubation in Ca++-enriched media, the water and electrolyte balance in the dextran 40-incubated group was essentially the same as that of lenses that were never exposed to a Ca++-free media. Those lenses that were not incubated in dextran 40 demonstrated significant residual lens swelling and electrolyte imbalance. It is concluded that dextran 40, by virtue of its oncotic effect, inhibits colloidal osmotic swelling and exerts a protective effect on lens function under a stress situation.