Questioning the need for routine bone marrow aspiration and lumbar puncture in patients with retinoblastoma

Purpose: This study assesses the value of routinely investigating children with retinoblastoma with bone marrow aspiration and lumbar puncture, staging investigations not without risk and trauma to the patient, emotional stress on parents and financial cost to the community. Methods: Medical files and specimens were obtained and examined for patients with retinoblastoma presenting to the Royal Alexandra Hospital for Children, Camperdown and the Children's Hospital at Westmead, Sydney, from 1975 to 2001. Results: In total, 123 patients presented; 62 (50.4%) were boys and 61 (49.6%) were girls. Of these 123 patients, 74 (60.2%) had unilateral disease, 46 (37.4%) involving the left eye and 28 (22.8%) involving the right eye. There were 47 (38.2%) patients with bilateral disease, and two (1.6%) with trilateral disease. Mean age of presentation was 17.9 months (23.1 months for unilateral subjects; 10.3 months for bi­lateral subjects; 3.5 months for trilateral subjects). There were 13 (10.6%) with a positive family history. Of 74 unilateral subjects, 70 (94.6%) required enucleation and four (5.4%) were salvaged. Of 47 bilateral subjects, 13 (27.7%) did not require enucleation, 27 (57.4%) required unilateral enucleation and seven (14.9%) required bilateral enucleation. Both trilateral subjects died. Of all 123 subjects, 112 (91.1%) had bone marrow aspiration and lumbar puncture performed during initial assessment, and none showed evidence of malignancy. Conclusions: Given the small but significant risks associated with these procedures, the results of this study cannot support bone marrow aspiration and lumbar puncture as routine investigations in all patients presenting with retinoblastoma, suggesting a more limited usage of these investigations is warranted.     

Reversal of pentylenetetrazol-induced potentiation phenomenon by theta pulse stimulation in the CA1 region of rat hippocampal slices

The effect of theta pulse stimulation (TPS) on pentylenetetrazol (PTZ)-induced long-term potentiation of population spikes was studied in the CA1 region of rat hippocampal slices. The field excitatory postsynaptic potential (fEPSP) and population spikes (PS) were recorded from strata radiatum and pyramidale, respectively, following stimulation of Schaffer collaterals. A transient PTZ application produced a long-lasting enhancement of PS amplitude. A 3-min episode of TPS delivered at test-pulse intensity failed to reverse the PTZ potentiation. However, the same stimulation at a higher intensity produced complete reversal of the PTZ potentiation when delivered during the last minutes of PTZ application. Prior application of high-intensity TPS also decreased the amount of PTZ potentiation, whereas it had no long-lasting effect on baseline synaptic responses. High-intensity TPS induced reversal was blocked by adenosine A1 receptor antagonist and, furthermore, was reduced by protein phosphatase 1 inhibitor. The results suggest that mechanism of PTZ-induced LTP reversal involves activation of adenosine receptors and protein phosphatases.     

Mitomycin C reduces corneal light scattering after excimer keratectomy

PURPOSE: To evaluate the effect of intraoperative mitomycin C (MMC) on corneal light scattering after excimer laser keratectomy. METHODS: Phototherapeutic keratectomy (PTK) was performed in 24 rabbit eyes. After 40-microm epithelial ablation, animals were divided into three groups. In group 1, filter paper discs soaked with MMC (group 1A, 0.5 mg/mL; group 1B, 0.25 mg/ml) were applied for 1 minute. In group 2, annular filter papers soaked with MMC (group 2A, 0.5 mg/mL; group 2B, 0.25 mg/mL) were applied for 1 minute. Controls received vehicle only (group 3). Six-millimeter diameter 100-microm deep PTK was performed. Corneal light scattering was measured weekly from 1 to 6 weeks, at 10 weeks, and at 8 and 13 months using a scatterometer. A corneal light scattering index (SI) ranging from 0 to 10 was calculated; SI of 1 represents normal scattering. RESULTS: A statistically significant decrease in mean SI was noted in group 2A (annular MMC 0.5 mg/mL; p<0.05) as compared with the control group at 2 weeks. At 10 weeks, SI approached baseline levels in group 2 and the control group but showed significant increase in group 1 (MMC disc; p < 0.05). At 8 and 13 months, SI showed no statistical differences between groups. CONCLUSIONS: Controlled application of 0.5 mg/mL MMC in the corneal midperiphery transiently reduces corneal light scattering after excimer keratectomy in this rabbit model.     

Corneal neovascularization

Corneal neovascularization (NV) is a sight-threatening condition usually associated with inflammatory or infectious disorders of the ocular surface. It has been shown in the field of cancer angiogenesis research that a balance exists between angiogenic factors (such as fibroblast growth factor and vascular endothelial growth factor) and anti-angiogenic molecules (such as angiostatin, endostatin, or pigment epithelium derived factor) in the cornea. Several inflammatory, infectious, degenerative, and traumatic disorders are associated with corneal NV, in which the balance is tilted towards angiogenesis. The pathogenesis of corneal NV may be influenced by matrix metalloproteinases and other proteolytic enzymes. New medical and surgical treatments, including angiostatic steroids, nonsteroidal inflammatory agents, argon laser photocoagulation, and photodynamic therapy have been effective in animal models to inhibit corneal NV and transiently restore corneal "angiogenic privilege."     

High protein vs high carbohydrate hypoenergetic diet for the treatment of obese hyperinsulinemic subjects

OBJECTIVE: To test the hypothesis that hyperinsulinemic obese subjects would respond differently to changes in the composition of hypoenergetic diets. DESIGN: A 4-week randomized dietary intervention trial. SUBJECTS: Thirteen male obese hyperinsulinemic normoglycemic subjects were divided into two groups and fed hypoenergetic diets providing 80% of their resting energy expenditure (REE). One group received a high-protein diet (HP; 45% protein, 25% carbohydrates, and 30% fat as percent of dietary energy) and the other a high-carbohydrate diet (HC; 12% protein, 58% carbohydrates and 30% fat). MEASUREMENTS: Anthropometry, body composition, fasting serum insulin and lipids, and REE were performed before and after the feeding period. RESULTS: Weight loss was higher in the HP than HC group (8.3+/-0.7 vs 6.0+/-0.6 kg, P<0. 05). There was a decrease in body fat in both groups, whereas body water decreased significantly more in the HP group. REE decreased more in the HC than the HP group (-384.3+/-84.6 vs -132.3+/-51.0 kcal, P<0.05). Serum total cholesterol, triglycerides and LDL cholesterol decreased significantly to a similar extent in both diet groups, while HDL cholesterol was decreased significantly only in the HP group. Mean fasting insulin decreased significantly in both diet groups and reached the normal range only in the HP group. CONCLUSION: A low-carbohydrate (LC), HP hypoenergetic diet could be the diet composition of choice for a weight-reducing regimen in obese hyperinsulinemic subjects.