Domenico Mastrangelo

Pathogenesis of posterior capsular opacification Part II: Histopathological and in vitro culture findings

ABSTRACT The most interesting sources of information about the pathogenesis of posterior capsular opacification seem to be histopathological studies and in vitro tissue cultures. Since our surgical technique is extracapsular cataract extraction, the explants we used for tissue culture consisted of the anterior capsule epithelial sheet without the equatorial germinative zone. We successfully overcame several problems by using the autologous plasma clot culture method. This medium, considered the optimal one for this type of culture, allowed us to study the heterogeneous behavior of the epithelial cells in culture. Using the plasma clot culture method, we were able to demonstrate in vitro fibroblastic transformation of the epithelial cells. Histopathological findings of particular cases of posterior capsule opacification and immunohistochemistry of the human lens are also reported.

Does the evidence matter in medicine? The retinoblastoma paradigm

Retinoblastoma (Rb) is the most common intraocular malignant tumour in childhood, with an incidence of 1 in 15,000 live births. Complete information on this rare tumour can be easily accessed through the internet, although many aspect concerning the aetiology and pathogenesis of the disease, are still controversial. The “two hit” theory, formulated in 1971 to explain the variegated clinical expression of the disease, is based on the idea that single gene mutation may determine the development of cancer. However, this view does not take into account the most recent evidences showing the role of aneuploidy and chromosome instability in cancer. Also, a number of other genes and epigenetic mechanisms are involved in the genesis of retinoblastoma. More importantly, the “two hit” theory makes predictions, concerning the age distribution of the tumour, its mode of “transmission” (hereditary retinoblastoma), and its pathogenesis, which are not fulfilled by the clinical reality. Overall, the “two hit” theory represents a rather simplistic and outdated model to explain tumour development and clinical evolution of retinoblastoma.

Mechanisms of anti-cancer effects of ascorbate: Cytotoxic activity and epigenetic modulation

Vitamin C (Vit C or Ascorbate) is essential for many fundamental biochemical processes. Vit C is an essential nutrient with redox functions at normal physiologic concentrations. The main physiologic function of this vitamin is related to its capacity to act as a co-factor for a large family of enzymes, collectively known as Fe and 2-oxoglutarate-dependent dioxygenases. It also modulates epigenetic gene expression through the control of TET enzymes activity. Vit C also has several biological properties allowing to restore the deregulated epigenetic response observed in many tumors. High-dose Vit C has been investigated as a treatment for cancer patients since the 1969. Pharmacologic ascorbate acts as a pro-drug for hydrogen peroxide formation (H2O2) and, through this mechanism, kills cancer cells. To achieve high in vivo concentrations, Ascorbate must be injected by i.v. route. Initial clinical studies of Ascorbate cancer treatment have provided encouraging results, not confirmed in subsequent studies. Recent clinical studies using i.v. injection of high-dose Ascorbate have renewed the interest in the field, showing that significant anti-tumor activity. Pre-clinical studies have led to identify tumors sensitive to Ascorbate that could potentially benefit from this treatment either through an epigenetic modulator effect or through tumor killing by oxidative stress.

High-dose ascorbate and arsenic trioxide selectively kill acute myeloid leukemia and acute promyelocytic leukemia blasts in vitro

The use of high-dose ascorbate (ASC) for the treatment of human cancer has been attempted several decades ago and has been recently revived by several in vitro and in vivo studies in solid tumors. We tested the cytotoxic effects of ASC, alone or in combination with arsenic trioxide (ATO) in acute myeloid leukemia (AML) and acute promyelocytic leukemia (APL). Leukemic cell lines and primary blasts from AML and APL patients were treated with graded concentrations of ASC, alone or in association with standard concentration (1 μM) of ATO. The ASC/ATO combination killed myeloid blasts, including leukemic CD34+ cells, while sparing CD34+ progenitors obtained from normal cord blood and bone marrow. Actually, approximately one-third (11/36) of primary AML cases were highly sensitive to the ASC/ATO combination. The mechanism of cell killing appeared to be related to increased oxidative stress and overproduction of ROS in a non-quantitative fashion, which resulted in induction of apoptosis. These effects were reverted by the addition of the antioxidant N-Acetyl-Cysteine (NAC). In the APL NB4 model, ASC induced direct degradation of the PML and PML/RARA proteins via caspase activation, while the transcriptional repressor DAXX was recruited in re-constituted PML nuclear bodies. Our findings encourage the design of pilot studies to explore the potential clinical benefit of ASC alone or in combination with ATO in advanced AML and APL.

The Polymerase Chain Reaction (PCR) In The Routine Genetic Characterization Of Retinoblastoma: A Tool For The Clinical Laboratory

The Polymerase Chain Reaction (PCR) is a highly innovative technique which allows for the generation of large amounts of DNA starting from minute quantities obtained from the blood or tissue of a patient. With the increasing knowledge concerning the structure of the human genome and the potential to amplify specific segments of DNA by the PCR technique, the molecular genetic characterization of many ocular disorders has been greatly facilitated. This is particularly true of retinoblastoma (RB) where the causative gene, RB1, gene has been identified and characterized. Using PCR technique, specific sequences of the RB1 gene can be amplified and analyzed to precisely define the genetic mutation in an affected individual. In addition, this technique can also be applied in order to characterize the genetic defect within the tumor itself. In this report we illustrate the use of the PCR technique in the genetic characterization of the RB1 gene and its application to the study of RB. These techniques are applicable even in a small clinical laboratory and can be extended to a number of ophthalmic disorders.

High Doses of Ascorbate Kill Y79 Retinoblastoma Cells In vitro

Objectives: To tests the sensitivity of Y79 retinoblastoma cell lines to high doses of ascorbate, in vitro, and compare its effects with those of some chemotherapeutic agents routinely employed in the treatment of retinoblastoma.Methods: Y79 retinoblastoma cells have been exposed to increasing doses of either sodium ascorbate (SA) or Melphalan (MEL), to define a dose-response curve around the peak plasma concentrations reached by both chemicals when administered according to the existing therapeutic procedures and protocols. The assessment of cell number and viability was performed, before and after exposure, with both the manual (Trypan Blue Exclusion Test) and automated (flow cytometry) methods. Fluorescence microscopy and direct observation of cells in culture, with inverted microscope, were also performed.Results: Y79 cells are highly sensitive to the cytotoxic effect of SA, with cell viability reduced of over 90% in some experiments. As reported in the literature, this effect is directly cytotoxic and most probably mediated by acute oxidative stress on different cellular components. The same does not apply to Melphalan which, at the doses commonly used for therapeutic purposes, did not show any significant effect on cell viability, in vitro.Conclusion: To our knowledge, this is the first report showing that high doses of SA can actively kill retinoblastoma cells in vitro. While it is not surprising for SA, to show direct cytotoxic effect on tumor cells, the data reported herein represent the first evidence in favor of the possible clinical use of high doses of intravenous SA, to treat children affected by retinoblastoma. Given the many advantages of SA over the chemotherapeutic agents commonly employed to treat cancer (including its almost total absence of toxic or side effects, and its exclusive specificity for cancer cells), it is reasonable to assume, from the data reported herein, that the high doses of intravenous ascorbate, have the potential to represent a real revolution in the treatment of retinoblastoma.

Growth of congenital malignant teratoid medulloepithelioma of the ciliary body: a case study

The purpose of this study was to describe the growth pattern of congenital malignant teratoid medulloepithelioma of the ciliary body by reporting clinical and imaging findings with pathological correlation. An 11-month-old little girl presented with a whitish-pink iris mass in the right eye resulting from a small ciliary body mass consistent with medulloepithelioma at both clinical and computed tomography (CT) findings. At CT, the lesion showed heterogeneous attenuation, without intraocular calcifications. Eleven months later, clinical and ultrabiomicroscopy showed a clear enlargement of the mass, which invaded the pupil. At magnetic resonance imaging (MRI), the lesion showed T1-weighted hyperintensity and T2-weighted slight hypointensity when compared to the vitreous and a notch in the anterolateral aspect of the ipsilateral lens. After intravenous gadolinium administration, the lesion showed intense homogeneous enhancement, and there was leakage of gadolinium in the anterior chamber, resulting from impairment of blood-aqueous barrier. Biopsy revealed a malignant teratoid medulloepithelioma. The eye was then enucleated, and histology confirmed the diagnosis. Systemic chemotherapy and radiotherapy were not performed, since there was no extraocular extension. The 57-month clinical and MRI follow-up did not show disease relapse. This uncommon case displays the natural history of congenital malignant teratoid medulloepithelioma of the ciliary body. While the tumour might have been successfully treated by local excision at diagnosis, the delay in surgical treatment led to tumour overgrowth with consequent need for enucleation. The most important prognostic feature is extraocular extension, which carries a risk of local recurrence, eventually resulting in intracranial extension and/or lymphatic spread.

Retinoblastoma and the genetic theory of cancer: an old paradigm trying to survive to the evidence.

Retinoblastoma (Rb) is considered to represent the prototype of cancer linked to the sequential loss or inactivation of both alleles of a so-called “tumor suppressor gene”, the Rb1 gene. The pathogenetic mechanism behind this tumor was first hypothesized by Knudson in 1971 and further confirmed by others who identified the Rb1 gene whose loss or inactivation was claimed to be responsible for the disease. However, after about four decades of continuous research in the field of molecular biology, the evidence behind the role of the Rb1 gene in Rb appears to be seriously flawed in the light of epidemiological, biological, and clinical evidences. This editorial summarizes the inconsistencies on this subject. Nevertheless, the molecular biology establishment still adheres to the biased view of the genetic origin of Rb and other cancers, and hardly any alternative explanations are taken into account.

Successful Treatment of Macular Retinoblastoma With Superselective Ophthalmic Artery Infusion of Melphalan

PURPOSE To report our experience with superselective ophthalmic artery infusion of melphalan (SOAIM) for macular retinoblastoma to obtain tumor control while preserving as much useful vision as possible. METHODS Five patients with newly diagnosed unilateral retinoblastoma involving the macula were selected within a group of patients eligible for SOAIM as the primary treatment. RESULTS The mean tumor basal dimension and thickness in this group of five patients with macular retinoblastoma were 11.6 and 12.3 mm, respectively. The stage at diagnosis ranged from II to VB (Reese-Ellsworth) or B to D (International Classification System). Tumor regression with SOAIM was achieved in all cases with regression patterns type I in four cases and III in one case. CONCLUSIONS SOAIM can be of value in the treatment of macular retinoblastoma. It may allow the salvage of the residual eyesight with a low rate of complications due to the local and systemic toxicity related to chemotherapy.

Phthisis bulbi and buphthalmos as presenting signs of retinoblastoma: a report of two cases and literature review.

Purpose To report two cases of bilateral retinoblastoma (RB) with unusual presentations. Methods The medical records of 321 patients from the Retinoblastoma Referral Center in Siena were reviewed. A total of 111 patients had bilateral RB, 2 of them presenting with phthisis bulbi and buphthalmos. Both patients underwent bilateral enucleation. Clinical features, imaging studies, and histopathology were reviewed. Results These 2 cases represent 0.62% (2/321) in our series. Histopathology did not reveal viable tumor cells in the phthisical eyes; in both buphthalmic eyes the tumor was active, infiltrating the choroid and optic nerve. Conclusions Phthisis bulbi and buphthalmos are unusual presenting signs of RB. This very rare combination of these two signs in different eyes of the same patient is probably due to a delay in diagnosis.