Neurotoxicity of Radiosurgery

Radiosurgery is a technique to deliver (in most cases) a single fraction of ionizing radiation, usually in the range of 10 to 25 Gy, to a precisely localized intracranial volume of pathological tissue. The radiobiological principles that govern the practice of single-fraction radiosurgery differ from those of conventional fractionated external beam radiation therapy. Rather, the results are primarily a consequence of either vascular effects or antiproliferative effects. The neurotoxicity of radiosurgery can be described according to its time course (immediate, acute, or chronic) and severity (mild, moderate, severe, life-threatening, or fatal( based on existing definitions established by the Radiation Therapy Oncology Group. Current indications for radiosurgery include arteriovenous malformations, acoustic neuromas, brain metastases, high-grade and other gliomas, meningiomas, and pituitary adenomas. The efficacy of radiosurgery and the time course and severity of radiosurgical neurotoxicity are dependent both on the nature of the lesion being treated and the normal tissue milieu which the lesion resides. This article describes the spectrum of neurotoxicity reported in the medical literature pertaining to the current variety of space-occupying lesions, benign tumors, and malignant neoplasms for which radiosurgery currently is being used.     

Xanthogranulomatous pyelonephritis in childhood: Ultrasound and CT diagnosis

Four cases of diffuse xanthogranulomatous pyelonephritis (XPN) in young children are presented. In three patients the clinical picture was one of weight loss, anaemia and neutrophilia with a large renal mass. The fourth presented with haematuria. Ultrasound (US) and CT findings were almost identical in all four patients. US showed the affected kidney was massively enlarged but retained a reniform shape. Dilated fluid spaces containing calculi were present. CT confirmed the US findings and revealed peripheral enhancement without contrast excretion, with dilated calyceal spaces producing the bear paw sign. Extrarenal extension into abdominal wall and psoas muscle is typical and was well demonstrated by CT. The affected kidneys were non-functioning and nephrectomy was required. Typical US and CT features allow a confident diagnosis of XPN and appropriate early treatment.     

The effect of congenital anomalies on mortality risk in white and black infants.

OBJECTIVES: This population-based study examined the effect of all major congenital anomalies on the mortality of White and Black infants by infant sex, birthweight, gestational age, and lethality of the anomaly. The study also determined the total contribution of anomalies to infant mortality. METHODS: California Birth Defects Monitoring Program data were merged with linked birth-death files for 278,646 singleton non-Hispanic White and Black infants born in 1983 through 1986. Malformed infants were compared with nonmalformed infants to determine the effect of anomalies on mortality. RESULTS: The presence of any congenital anomaly increased mortality 9.0-fold (95% CI = 7.3, 11.1) for Black infants and 17.8-fold (95% CI = 16.2, 19.6) for White infants. Even "non-lethal" anomalies increased mortality up to 8.9-fold. Overall, anomalies contributed to 33% of White infant deaths, to 19% of Black infant deaths, and to over 60% of deaths among Black and White neonates weighing over 1499 g. CONCLUSIONS: The contribution of congenital anomalies to mortality of both low- (< 2500 g) and normal-birth-weight infants is substantially higher than previously estimated, representing a large public health problem for both Black and White infants.     

Medical issues relating to the Sydney Olympic Games

The Sydney Olympic Games in 2000 represent a significant medical and sporting challenge. Prior planning is the key to optimal performance, and team medical staff should be familiar with major medical and injury concerns of athletes and officials well prior to departure. A comprehensive team medical kit should be organised. Travel will be over great distances for many teams, so particular attention to optimising sleep and hydration is essential. The Olympic village experience can be overwhelming for some athletes, and medical staff should provide informed advice on food, transport and safety issues. Heat is less likely to be an issue than at recent summer Olympic Games, but should not be ignored completely. Major incidents can occur at any major sporting festival, and team medical staff should be appropriately prepared for these. All team medical staff should be aware of the current list of banned substances, and seek to minimise drug use by their athletes. After the event, an appropriate debriefing session should be held with a view to planning improvements for the future.     

Regulatory peptides in the heart and major vessels of man and mammals

Studies on the distribution of peptides in human tissues have been made either by measuring responses to localized stimuli or by subjecting extracts of different regions to radioimmunoassay (RIA). Attempts at isolating regulatory peptides from the mammalian tissues have resulted in the isolation of many bioactive fragments. Later, modification of initial isolation methods led to the identification of the native molecules in various tissues and body fluids. The present study examined atrial natriuretic peptide (ANP) and several other peptides in cardiac tissues of several species of laboratory mammal and human beings; using a sensitive and highly specific radioimmunoassays.In all the species studied, ANP-like immunoreactivity appeared to be highest in the heart tissue of rat. The peptide was highest in the right atrium (RA) of rat and lowest in the RA of guinea pig (P< 0.002). Neuropeptide Y (NPY) another abundant cardiac peptide was present in the cardiac tissues of all species but was more in the left atrium (LA) than the RA of all species (P<0.05). Calcitonin gene-related peptide (CGRP) was present throughout the cardiovascular system of the rat and guinea pig. Small but detectable amount of Neurotensin (NT) immunoreactivity was found in the rat but was consistently negative in the guinea pig cardiac tissues (P< 0.05). Substance P (SP) immunoreactivity was detected in the rat and higher quantities being in the Aorta but no trace of the peptide was detected in the left ventricle, aorta nor the pulmonary vein of post mortem human.Though the structure of most of the species studied has been elucidated, the primary structure of guinea pig ANP has not been fully generated. Thus the data obtained may suggest that in keeping with these mammalian peptides, the primary structures may be variant. With most of the peptides studied (e.g. ANP, Neuropepdide Y), immunoreactivity occurs predominantly in the atrial tissues, but is also present in vessels outside the heart, a finding which may be of functional significance.     

Enhanced learning of proportional math through music training and spatial-temporal training

It was predicted, based on a mathematical model of the cortex, that early music training would enhance spatial-temporal reasoning. We have demonstrated that preschool children given six months of piano keyboard lessons improved dramatically on spatial-temporal reasoning while children in appropriate control groups did not improve. It was then predicted that the enhanced spatial-temporal reasoning from piano keyboard training could lead to enhanced learning of specific math concepts, in particular proportional math, which is notoriously difficult to teach using the usual language-analytic methods. We report here the development of Spatial-Temporal Math Video Game software designed to teach fractions and proportional math, and its strikingly successful use in a study involving 237 second-grade children (age range six years eight months-eight years five months). Furthermore, as predicted, children given piano keyboard training along with the Math Video Game training scored significantly higher on proportional math and fractions than children given a control training along with the Math Video Game. These results were readily measured using the companion Math Video Game Evaluation Program. The training time necessary for children on the Math Video Game is very short, and they rapidly reach a high level of performance. This suggests that, as predicted, we are tapping into fundamental cortical processes of spatial-temporal reasoning. This spatial-temporal approach is easily generalized to teach other math and science concepts in a complementary manner to traditional language-analytic methods, and at a younger age. The neural mechanisms involved in thinking through fractions and proportional math during training with the Math Video Game might be investigated in EEG coherence studies along with priming by specific music.     

Chemokine receptor mRNA expression at the in vitro blood-brain barrier during HIV infection

Viral entry through the blood-brain barrier (BBB) has not been fully defined and identification of coreceptors that can facilitate this phenomenon is crucial in understanding disease progression. Using a RNAse protection assay to examine chemokine receptor families simultaneously, we analyzed the total RNA of in vitro BBB cultures treated with purified preparations of HIV gp120, gp41, TAT proteins and TNF-alpha. HIV tat protein affected CCRI and CCR3 mRNA expression whereas the other viral by-products had no effect. Interestingly, TNF-alpha was able to induce CCR1, CCR3 as well as CXCR1, CXCR2, CXCR4 receptors and Burkitt's lymphoma receptor BLR2. These results suggest that HIV-induced molecules can manipulate the surface receptor expression of the BBB to allow for their preferential entry into brain.