Therapy for Vitreous Seeding Caused by Retinoblastoma. A Review.

Retinoblastoma is the most common primary malignant intraocular tumor in children. Seeding, specifically the dispersion of the tumor into the adjacent compartments, represents a major parameter determining the degree of retinoblastoma according to the International Classification of Retinoblastoma. In this article we focused on vitreous seeding, one of the main limiting factors in the successful "eye preservation treatment" of retinoblastoma. This article presents an overview of the history of vitreous seeding of retinoblastoma, established treatment procedures and new-research modalities. The introduction of systemic chemotherapy in the treatment of retinoblastoma at the end of the 1990s represented a significant breakthrough, which enabled the progressive abandonment of radiotherapy with its attendant side effects. However, the attained concentrations of chemotherapeutics in the vitreous space during systemic chemotherapy are not sufficient for the treatment of vitreous seeding, and the toxic effects of systemic chemotherapy are not negligible. A significant change came with the advent of chemotherapy in situ, with the targeted administration of chemotherapeutic drugs, namely intra-arterial and intravitreal injections, contributing to the definitive eradication of external radiotherapy and a reduction of systemic chemotherapy. Although vitreous seeding remains the most common reason for the failure of intra-arterial chemotherapy, this technique has significantly influenced the original treatment regimen of children with retinoblastoma. However, intravitreal chemotherapy has made the greatest contribution to increasing the probability of preservation of the eyeball and visual functions in patients with advanced findings. Novel local drug delivery modalities, gene therapy, oncolytic viruses and immunotherapy from several ongoing preclinical and clinical trials may represent promising approaches in the treatment of vitreous retinoblastoma seeding, though no clinical trials have yet been completed for routine use.

Therapy for Vitreous Seeding Caused by Retinoblastoma. A Review.

Retinoblastoma is the most common primary malignant intraocular tumor in children. Seeding, specifically the dispersion of the tumor into the adjacent compartments, represents a  major parameter determining the degree of retinoblastoma according to the International Classification of Retinoblastoma. In this article we focused on vitreous seeding, one of the main limiting factors in the successful "eye preservation treatment" of retinoblastoma. This article presents an overview of the history of vitreous seeding of retinoblastoma, established treatment procedures and new-research modalities. The introduction of systemic chemotherapy in the treatment of retinoblastoma at the end of the 1990s represented a  significant breakthrough, which enabled the progressive abandonment of radiotherapy with its attendant side effects. However, the attained concentrations of chemotherapeutics in the vitreous space during systemic chemotherapy are not sufficient for the treatment of vitreous seeding, and the toxic effects of systemic chemotherapy are not negligible. A significant change came with the advent of chemotherapy in situ, with the targeted administration of chemotherapeutic drugs, namely intra-arterial and intravitreal injections, contributing to the definitive eradication of external radiotherapy and a reduction of systemic chemotherapy. Although vitreous seeding remains the most common reason for the failure of intra-arterial chemotherapy, this technique has significantly influenced the original treatment regimen of children with retinoblastoma. However, intravitreal chemotherapy has made the greatest contribution to increasing the probability of preservation of the eyeball and visual functions in patients with advanced findings. Novel local drug delivery modalities, gene therapy, oncolytic viruses and immunotherapy from several ongoing preclinical and clinical trials may represent promising approaches in the treatment of vitreous retinoblastoma seeding, though no clinical trials have yet been completed for routine use.

The role of near-infrared spectroscopy monitoring in preterm infants.

Neurological morbidities such as peri/intraventricular hemorrhage and periventricular leukomalacia largely determine the neurodevelopmental outcome of vulnerable preterm infants and our aim should be to minimize their occurrence or severity. Bed-side neuromonitoring could provide valuable pieces of information about possible hemodynamic disturbances that are significantly associated with neurological morbidities and increased mortality. Near-infrared spectroscopy offers evaluation of regional cerebral oxygenation, which in conjunction with other non-invasive methods may give us a more complete picture about end-organ perfusion. This monitoring tool could help us fully understand the pathophysiology of severe neurological morbidities and guide our management in order to reduce their incidence.

The use of a hydrogel matrix for controlled delivery of niacin to the gastrointestinal tract for treatment of hyperlipidemia.

Hyperlipidemia treatment based on niacin requires gastrointestinal administration of relatively high doses. The recommended dietary allowance of niacin as vitamin B3 is 14 to 16 mg daily in adults, while the doses of niacin used in the treatment of hyperlipidemia are generally in the range of 1 to 3 g. Administration of such large doses requires a high concentration of the active compound in the tablet and proper control of the drug release. In this study, a hydrogel matrix based on poly(2-hydroxyethyl methacrylate) and polyvinylpyrrolidone was investigated as delivery vehicle for controlled NA release into the gastrointestinal environment. The prepared hydrogel matrices varied in used monomer and crosslinker types and concentrations. The content of NA in tablets was between 65-80 %. The release profiles of NA from tablets were examined under three different pH values (1, 4.5 and 6.8) over the time period of 30 h. The effects of the monomer ratio, the crosslinking of the polymer network, and the solubility of niacin during drug release under various pH are discussed. The results showed that the release time period can be achieved in a relatively wide range of time and can be adjusted according to the medical requirements.

Diastolic ventricular function improves during the first 48-hours-of-life in infants weighting <1250 g.

AIM: Few studies have focused on cardiac ventricular diastolic function in preterm neonates in the immediate post-natal period. This study evaluated Doppler-derived parameters of diastolic ventricular function in infants with birth weights of <1250 g during the transitional period. METHODS: This was a prospective observational study conducted in the Coombe Women and Infants University Hospital in Dublin, Ireland. Flow patterns on the mitral and tricuspid valve, isovolumic relaxation time (IVRT), left and right ventricular output and superior vena cava flow were measured in 22 infants with a birth weight of below 1250 g at six, 12, 24 and 48 h of age. RESULTS: Early filling peak velocity of the left and right ventricle increased significantly from 30.3 to 39.5 cm/sec and 26.6 to 32.1 cm/sec, respectively. IVRT of the right ventricle decreased from 70 to 57 ms, and there was a nonsignificant decrease in IVRT of the left ventricle from 61.6 to 54 ms over the first 48 h. CONCLUSION: We have demonstrated that parameters of diastolic ventricular function change significantly over the first 48 h of life in preterm infants <1250 g and that these changes may represent early diastolic dysfunction during the transitional period.

Cerebral tissue oxygenation index, cardiac output and superior vena cava flow in infants with birth weight less than 1250 grams in the first 48 hours of life.

BACKGROUND: Near-infrared spectroscopy is a non-invasive method of assessing cerebral oxygenation. Functional echocardiography is increasingly used by neonatologists in the assessment of cardiovascular function. AIMS: To correlate cerebral tissue oxygenation index (cTOI) and cardiac output in infants less than 1250 g at 6, 12, 24 and 48 hours of age. STUDY DESIGN: A prospective observational study. SUBJECTS: Newborns with birth weight<1250 g. OUTCOME MEASURES: Serial assessments of superior vena cava (SVC) flow, right and left ventricular outputs, ductus arteriosus and cTOI were performed at 6, 12, 24 and 48 hours of age. Clinical parameters, including mean blood pressure, mean airway pressure, blood gas parameters and oxygen saturations were recorded. RESULTS: 22 neonates were enrolled following parental consent. The mean birth weight was 851 g (SD±201), mean gestational age was 25.9 weeks (SD±1.7). Mean SVC flow at 6 hours of age was 56.8 ml/kg/min and increased to 68.6 ml/kg/min at 48 hours of age. 9 infants (41%) had at least one measurement of low SVC flow (<41 ml/kg/min) in the first 48 hours. Mean cTOI was 65.2% at 6 hours of age, 63.9% at 12 hours of age, 68.8% at 24 hours of age and 67.2% at 48 hours of age. Cerebral fractional tissue oxygen extraction values were highest at 12 hours (0.31±0.09). There was no correlation between SVC flow and cTOI values. CONCLUSION: SVC flow, left and right ventricular output increased during first 48 hours of life. cTOI decreased at 12 hours of age with a concomitant increase in fractionated oxygen extraction. These changes reflect transitional changes in both cardiac and cerebral hemodynamics in extremely low gestational age newborns during the first 48 hours.

Changes of corneal optical properties after UVB irradiation investigated spectrophotometrically.

Ozone depletion leads to an increase in UV rays of solar radiation reaching the surface of the Earth which is harmful to biological systems. Of the eye, the cornea is directly open to increased amount of UV rays of which mainly UVB rays are capable to induce reactive oxygen species damaging the cells. Previous studies showed that the irradiation of the cornea with UVB rays leads to morphological as well as metabolic disturbances of the cornea. Also, corneal hydration and corneal light absorption are increased after UVB rays. These changes were observed after five days of repeated irradiation of the cornea with UVB rays. The aim of the present paper was to examine how early the changes of corneal hydration and light absorption occur after UVB irradiation. The rabbit corneas were irradiated with UVB rays for one, two, three or four days. Corneal light absorption was examined spectrophotometrically and corneal hydration measured by pachymeter (as corneal thickness). Results show that changes of corneal hydration and light absorption appear early after UVB irradiation and increase along with the number of irradiations. In conclusion, irradiation of the rabbit cornea with UVB rays leads to harmful changes of its optical properties.