Colour-coded ganglion cells in the goldfish retina: extension of their receptive fields by means of new stimuli

1. Receptive fields of colour-coded ganglion cells of the goldfish retina were investigated.2. Only a few cells (5%, Type P) were found to be as simple as those described by Wagner, MacNichol & Wolbarsht (1960, 1963), with an ;on' response to red light in the centre, and an ;off' response to green light over a rather wider area, or vice versa.3. Most cells (49%, Type O) also gave a peripheral response with an ;on' response to green light, and an ;off' response to red light in the periphery, as well as an ;on' response to red light and an ;off' response to green light in the centre (or vice versa).4. When a small spot of light was used to stimulate the periphery of a Type O cell, the peripheral response usually was not obtained. The organization of the periphery is such that a stimulus of large area and low intensity (annulus) is much more effective than a stimulus having equal energy with small area and high intensity (spot). If only small spots are used, the Type O cell is indistinguishable from the Type P cell.5. Spectral sensitivity measurements show that one central and one peripheral process are fed primarily by red-absorbing cones, and the other central and the other peripheral process by green-absorbing cones or rods.6. The diameter of the receptive field as a whole is very large, being 5 mm or more on the retina.7. When red spots in green surrounds, or red/green boundaries are used as stimuli, the response can be predicted by summing the responses to the components of the stimulus.8. This type of receptive field organization is appropriate to mediate simultaneous colour contrast. The ;opponent colour' organization previously reported is appropriate for successive colour contrast, but not for simultaneous colour contrast.9. The component of the response coming from the green-absorbing cones was masked or hidden by the component of the response coming from the red-absorbing cones in 14% of the units (Type Q units). The component from the green-absorbing cones was revealed by using a high intensity of stimulation, or by observing the response after bleaching pigment with an intense red light.     

Pulsatile Ovarian Fossa Ectopic and the 'Morning After' Pill

EDITORIAL COMMENT: This case report was accepted for publication mainly to remind readers that withdrawal haemorrhage does not exclude pregnancy, in-trauterine or extrauterine, when 'morning after' pills are prescribed. These patients also require an appropriately-timed HCG assay, oestrogen and/or progesterone assay or ultrasonography. The pulsatile nature of this ectopic gestation, whether ovarian or primary peritoneal, is unusual. Conjecture on aetiology is unwarranted without knowledge of the time in the menstrual cycle that morning after pills were taken.     

Management of relapsed and refractory classical Hodgkin lymphoma in children and adolescents

There are a number of options for salvage treatment in children and adolescents with relapsed and refractory classical Hodgkin Lymphoma. These include salvage with standard dose chemotherapy, high dose chemotherapy with autologous stem cell transplant, allogeneic stem cell transplant or other novel approach. Radiotherapy has an important role in the salvage of some patients as part of a combined modality approach. This review outlines these salvage approaches and discusses whether the evidence from paediatric studies justifies a risk-adapted approach to salvage for individual patients or whether all patients should receive consolidation with high dose chemotherapy and autologous stem cell transplantation, which is often described as standard salvage management in adults. The important prognostic factors and how these may be used to allocate patients to standard versus high dose chemotherapy regimens are discussed. The role of allogeneic transplantation, novel agents and late effects will also be discussed.     

Management of major blunt pediatric renal trauma: Single-center experience

ObjectiveTo review the impact of major pediatric renal trauma and its management on long-term function and morphology of the injured kidney.MethodsThirty-six blunt trauma patients (20 males, 16 females) presented in 2004–2007 (age range 2 days to 14 years; mean 6.2 years). Thirty-seven renal units were included: 13 grade III, 14 grade IV, and 10 grade V injuries. Follow up was for 3–38 (mean 14) months. Patients were managed non-operatively unless vitally unstable. The most common causes of trauma were motor vehicle accidents and falls. Fourteen patients had associated non-renal injuries. Four patients had pre-existing renal problems.ResultsThe surgical intervention group (13 patients, 36%) included 9/10 grade V and 4/14 grade IV renal injuries. Surgical repair of lacerations was performed in seven cases, partial nephrectomy in four cases and nephrectomy in two cases. Follow up showed no significant change in renal function, and none developed hypertension. The non-operative group (24 patients, 63.2%) included all grade III injuries, 10 grade IV injuries, and one grade V injury. There was an excellent outcome for 18/24 patients (75%) with kidney preservation, no complications from urinary extravasation and hematoma resolution. The remaining patients had lower polar infarction (1), renal atrophy (1), persistent subcapsular collection (2), recurrent hematuria requiring angioembolization (1), and there was one death related to central nervous system injury.ConclusionThe outcome of our management of pediatric major renal trauma was favorable overall. Longer follow up is needed with regard to renal function and development of hypertension.     

Adipose tissue engineering by human adipose-derived stromal cells

Tissue engineering has emerged as a promising alternative approach to current clinical treatments for restoration of soft tissue defects. The purpose of this study was to investigate adipose tissue formation in vitro and in vivo by using human adipose-derived stromal cells (ADSCs) utilizing a gelatin sponge (Gelform) as a scaffold. Adipogenic potentials of human ADSCs were demonstrated by Oil-O-red staining and cellular morphology. After seeding human ADSCs in a density of 3 x 10(6) cells/ml on three-dimensional gelatin sponges, tissue-engineered constructs were exposed to adipogenic differentiation medium for in vitro studies and implanted in the backs of severe combined immunodeficient (SCID) mice for in vivo adipose regeneration. Adipogenesis of ADSC-seeded gelatin sponges was confirmed by Oil-O-red staining after 4 weeks of in vitro incubation. The optical density of the elution from Oil-O-red staining of adipogenic constructs is significantly higher than that of the control group (p < 0.05, n = 4). With short-term in vitro differentiation, adipogenic constructs turned into fat tissue 4 weeks after in vivo implantation, confirmed by biochemical and immunohistochemical examination. No adipogenic-morphological change or fat formation was observed in in vitro or in vivo studies when ADSCs were exposed to a control medium without adipogenic stimulation. These results indicate that engineered adipose tissue can be achieved using human ADSCs and biocompatible and degradable gelatin sponges.     

Immune thrombocytopenia in adults: An update

Immune thrombocytopenia (ITP) in adults is a chronic disease resulting from increased platelet destruction and impaired platelet production. Splenectomy remains the most effective and durable treatment in cases that are refractory to first-line therapy, but its use has declined because of the availability of alternate medical therapy, the associated risk of infection, and concern for surgery-related complications. Rituximab (Rituxan) may be an effective alternative but carries the risk of immunosuppression.