Beam angle manipulation to reduce cardiac dose during breast radiotherapy.

OBJECTIVE: Standard tangential radiotherapy techniques after breast conservative surgery (BCS) often results in the irradiation of the tip of the left ventricle and the left anterior descending coronary artery (LAD), potentially increasing cardiovascular morbidity. The importance of minimising radiation dose to these structures has attracted increased interest in recent years. We tested a hypothesis that in some cases, by manipulating beam angles and accepting lower-than-prescribed doses of radiation in small parts of the breast distant from the surgical excision site, significant cardiac sparing can be achieved compared with more standard plans. METHODS: A sample of 12 consecutive patients undergoing radiotherapy after left-sided BCS was studied. All patients were planned with a 6 MV tangential beam, beam angles were manipulated carefully and if necessary lower doses were given to small parts of the breast distant from the surgical excision site to minimise cardiac irradiation ("institutional" plan). Separate "hypothetical standard" plans were generated for seven patients using set field margins that met published guidelines. RESULTS: In seven patients, the institutional plans resulted in lower doses to the LAD and myocardium than the hypothetical standard plans. In the other five patients, LAD and myocardial doses were deemed minimal using the hypothetical standard plan, which in these patients corresponded to the institutional plan (the patients were actually treated using the institutional plans). CONCLUSION: Much attention has been devoted to ways of minimising cardiac radiation dose. This small sample demonstrates that careful manipulation of beam angles can often be a simple, but effective technique to achieve this.

The prognostic significance of computerised tomography findings in women with liver metastases from breast cancer.

AIMS: While computerised tomography (CT) is used for diagnosis and assessing response to treatment little work has been performed on the prognostic significance of the CT findings in women with liver metastases. The aim of this study was to assess if the CT findings in women diagnosed with liver metastases at the time of first presentation with metastatic breast cancer have any prognostic significance. MATERIALS AND METHODS: The staging CT scans of 78 consecutive women diagnosed with liver metastases at the time of first presentation of metastatic breast cancer were reviewed independently by two radiologists who were blinded to survival and the histological features of the tumour. The number and enhancement characteristics of liver metastases, whether metastases were solitary, multiple or diffuse, the diameter of the largest and the sum of the diameter of the five largest lesions, an estimate of % involvement (<10%, 10-50%, >50%), and the presence of metastases at other sites were assessed. HER-2 and ER status and histological grade of the patient's primary breast cancer were also recorded. Survival was ascertained from hospital records. The prognostic significance of these factors was assessed in a univariate and multivariate fashion. RESULTS: At univariate analysis, number of liver metastases, sum of the diameter of the five largest lesions, percentage estimated involvement, presence of ascites, chest metastases and HER-2 status were significantly associated with reduced survival. Liver metastasis pattern (i.e. whether discrete or multiple), enhancement characteristics, ER status and histological grade were not associated with a significant outcome. At multivariate analysis estimated percentage liver involvement and the presence of chest metastases retained prognostic significance. Estimated percentage involvement was reproducible with 90% concordance between the two observers. CONCLUSIONS: The CT appearances of patients with liver metastases at first presentation with metastatic breast cancer provide prognostic information which may be clinically useful.

Alcohol-related head injury: impact on acute CT workload in a major trauma centre.

National guidelines exist for the investigation and early management of head injury. Alcohol-related head injury is relatively common in clinical practice, and intoxicated patients can be difficult to fit into guidelines for imaging. A sequential retrospective study compared imaging findings of alcohol-related injuries to sober control cases. We demonstrate that in normal clinical practice in a major trauma centre, a GCS15 patient with alcohol-related head injury selected to undergo imaging by the Emergency Department team, is more likely to have an abnormality on CT than a sober patient (p = 0.014). Despite the potential for guidelines to lead to many further (and possibly inappropriate) CT investigations to be performed in the intoxicated patient group, this is not demonstrated to be the case in our centre.

Trypanosoma brucei brucei crosses the blood-brain barrier while tight junction proteins are preserved in a rat chronic disease model.

African trypanosomiasis, sleeping sickness in humans, is caused by the systemic infection of the host by the extracellular parasite, the African trypanosome. The pathogenetic mechanisms of the severe symptoms of central nervous system involvement are still not well understood. The present study examined the routes of haematogenous spread of Trypanosoma brucei brucei (Tbb) to the brain, in particular on the question whether parasites can cross the blood-brain barrier, as well as their effect on tight junction proteins. Rats were infected with Tbb and at various times post-infection, the location of the parasite in the central nervous system was examined in relation to the brain vascular endothelium, visualized with an anti-glucose transporter-1 antibody. The tight junction-specific proteins occludin and zonula occludens 1, and the possible activation of the endothelial cell adhesion molecules ICAM-1 and VCAM-1 were also studied. At 12 and 22 days post-infection, the large majority of parasites were confined within blood vessels. At this stage, however, some parasites were also clearly observed in the brain parenchyma. This was accompanied by an upregulation of ICAM-1/VCAM-1. At later stages, 42, 45 and 55 days post-infection, parasites could still be detected within or in association with blood vessels. In addition, the parasite was now frequently found in the brain parenchyma and the extravasation of parasites was more prominent in the white matter than the cerebral cortex. A marked penetration of parasites was seen in the septal nuclei. In spite of this, occludin and zonula occludens 1 staining of the vessels was preserved. The results indicate that the Tbb parasite is able to cross the blood-brain barrier in vivo, without a generalized loss of tight junction proteins.

Chronic sodium salicylate treatment exacerbates brain neurodegeneration in rats infected with Trypanosoma brucei.

We have reported previously that axonal degeneration in specific brain regions occurs in rats infected with the parasite Trypanosoma brucei. These degenerative changes occur in spatiotemporal association with over-expression of pro-inflammatory cytokine messenger RNAs in the brain. To test how aspirin-like anti-inflammatory drugs might alter the disease process, we fed trypanosome-infected rats with 200mg/kg of sodium salicylate (the first metabolite of aspirin) daily in their drinking water. Sodium salicylate treatment in uninfected rats did not cause any neural damage. However, sodium salicylate treatment greatly exacerbated neurodegeneration in trypanosome-infected rats, resulting in extensive terminal and neuronal cell body degeneration in the cortex, hippocampus, striatum, thalamus, and anterior olfactory nucleus. The exaggerated neurodegeneration, which occurred in late stages of infection, was temporally and somewhat spatially associated with a late-appearing enhancement of messenger RNA expression of interleukin-1beta, interleukin-1beta converting enzyme, tumor necrosis factor-alpha, and inhibitory factor kappaBalpha in the brain parenchyma. Restricted areas showed elevations in messenger RNA expression of interleukin-1 receptor antagonist, interleukin-6, inducible nitric oxide synthase, interferon-gamma, and inducible cyclooxygenase. The association suggests that increased production of pro-inflammatory cytokines in the brain may be an underlying mechanism for neural damage induced by the chronic sodium salicylate treatment. Furthermore, the results reveal a serious complication in using aspirin-like drugs for the treatment of trypanosome infection.

Chronic overexpression of proinflammatory cytokines and histopathology in the brains of rats infected with Trypanosoma brucei.

Overproduction of proinflammatory cytokines in the brains of transgenic animals causes brain pathology. To investigate the relationship between brain cytokines and pathology in the brains of animals with adult-onset, pathophysiologically induced brain cytokine expression, we studied rats infected with the parasite Trypanosoma brucei. Several weeks after infection, in situ hybridization histochemistry showed a pattern of chronic overexpression of the mRNAs for proinflammatory cytokines interleukin-1beta and tumor necrosis factor-alpha in the brains of the animals. Similar spatiotemporal inductions of mRNAs for inhibitory factor kappaBalpha and interleukin-1beta converting enzyme were found and quantified. The mRNAs for inducible nitric oxide synthase and interleukin-1 receptor antagonist were highly localized to the choroid plexus, which showed evidence of structural abnormalities associated with the parasites' presence there. The mRNAs for interleukin-6, interferon-gamma, and inducible cyclooxygenase showed restricted induction patterns. Another set of animals was processed for degeneration-induced silver staining, TdT-mediated dUTP-digoxigenin nick end-labeling (TUNEL) staining, glial fibrillary acidic protein (GFAP) immunohistochemistry, and several other histological markers. Apoptosis of scattered small cells and degeneration of certain nerve fibers was found in patterns spatially related to the cytokine mRNA patterns and to cerebrospinal fluid diffusion pathways. Furthermore, striking cytoarchitectonically defined clusters of degenerating non-neuronal cells, probably astrocytes, were found. The results reveal chronic overexpression of potentially cytotoxic cytokines in the brain and selective histopathology patterns in this natural disease model. J. Comp. Neurol. 414:114-130, 1999. Published 1999 Wiley-Liss, Inc.

African trypanosomiasis in the rat alters melatonin secretion and melatonin receptor binding in the suprachiasmatic nucleus.

Rats infected with Trypanosoma brucei brucei, a subspecies of the extracellular parasites that cause African sleeping sickness, were examined for disturbances in the circadian rhythms of melatonin secretion (evaluated by determination of the excretion of melatonin in the urine) and the binding of melatonin to its receptor in the suprachiasmatic nuclei of the anterior hypothalamus. In normal and infected rats, Cosinor analysis showed a significant nocturnal peak. The amplitude of this peak was, however, significantly decreased in the infected rats. The peak of melatonin receptor binding in the suprachiasmatic nuclei showed a 4-h phase advance in the infected rats, compared with the controls (0400 and 0800, respectively). These data point to a disturbance in the circadian rhythm of the melatonin-generating systems in the pathogenesis of African sleeping sickness.

Expression of an oscillating interferon-gamma receptor in the suprachiasmatic nuclei.

The suprachiasmatic nuclei serve as the dominant circadian pacemaker in the mammalian brain, regulating daily behavioral, physiological and hormonal rhythms. In the ventrolateral parts of these nuclei, the receptor for the key immunoregulatory molecule interferon-gamma (IFN-gamma) was detected in the rat brain. The cellular localization of the IFN-gamma receptor corresponded to neuronal elements. Expression of the receptor followed a diurnal rhythm with a peak at zeitgeber time 15. This peak coincided with an enhanced expression of janus kinase 1 and 2 as well as the signal transducer and activator of transcription 1, which constitute the main intracellular signaling pathway of IFN-gamma. This is the first study to show expression of the receptor of an immune modulatory molecule in the pacemaker of the biological clock, which, thus, may be influenced by immune system signal molecules.

Altered neuronal activity rhythm and glutamate receptor expression in the suprachiasmatic nuclei of Trypanosoma brucei-infected rats.

The parasites Trypanosoma brucei cause African trypanosomiasis (sleeping sickness), a severe neuropsychiatric disease with marked disturbances of sleep-wake alternation. The sites of brain lesions are not well characterized. The present experimental investigation is focused on the hypothalamic suprachiasmatic nuclei, which play a role of a biological clock entraining endogenous rhythms in the mammalian brain. The electrophysiological properties of these neurons were analyzed in slice preparations from trypanosome-infected rats. The neuronal spontaneous activity, which shows a circadian oscillation, was markedly altered in the infected animals, displaying a reduced firing rate and phase advance of its circadian peak. The direct retinal fibers, which play a pivotal role in entrainment of the circadian pacemaker, displayed a normal density and distribution in the suprachiasmatic nuclei of infected animals after intraocular tracer injections in vivo. At the postsynaptic level, immunohistochemistry and Western blotting revealed in the suprachiasmatic nuclei of infected rats a selective decrease of the expression of glutamate AMPA GluR2/3 and NMDAR1 receptor subunits that gate retinal afferents. These data disclose an impairment of the neuronal functions in the biological clock in African trypanosomiasis, and may serve to unravel functional and molecular mechanisms behind endogenous rhythm disturbances.

Interferon-gamma receptors in nociceptive pathways: role in neuropathic pain-related behaviour.

Interferon-gamma receptor (IFN-gamma R) immunoreactivity was observed in the superficial dorsal horn and lateral spinal nucleus in rat and mouse spinal cord. Dorsal rhizotomies did not reduce immunoreactivity in the rat. IFN-gamma R distribution overlapped with nitric oxide synthase-1 immunoreactivity. In wild-type mice, intrathecal injections of mouse IFN-gamma evoked biting behaviour, whereas mice with disruption of the functional gene for IFN-gamma R did not respond. Both types of mice had similar withdrawal thresholds to mechanical stimulation and reacted similarly to foot-pad carrageenan injections. In contrast to wild-type mice, IFN-gamma R knock-out mice did not show autotomy after sciatic nerve section. This study demonstrates a functional IFN-gamma R in spinal nociceptive pathways related to neuropathic pain.

Neurobiology of cerebral malaria and African sleeping sickness.

This review is aimed at emphasizing the need for basic neuroscience research on two tropical diseases, malaria and sleeping sickness (African trypanosomiasis), that still represent major health problems and in which severe involvement of the nervous system is frequently the direct cause of death. The life cycles of the two parasites, the protozoan Plasmodium and Trypanosoma brucei, which are the causative agents of malaria and sleeping sickness, respectively, are briefly reviewed. The historical contribution to the pathogenesis and therapy of malaria by a renowned pioneer in neuroscience, Camillo Golgi, is pointed out. The different strategies for survival in the host by the intracellular Plasmodium and the extracellular African trypanosomes are summarized; such strategies include sites favorable for hiding or replication of the parasites in the host, antigenic variation, and interactions with the cytokine network of the host. In particular, tumor necrosis factor-alpha and interferon-gamma may play a role in these infections. The parasites may paradoxically interact with cytokines to their benefit. However, cytokine receptors are expressed on neuronal subsets sensitive to cytokine action, and stimulation of these subsets may cause neuronal dysfunctions during the infections. Finally, the clinical symptoms of cerebral malaria and African trypanosomiasis and research aiming at deciphering their pathogenetic mechanisms that could affect the nervous system at a molecular level are described. The need for neuroscientists in this endeavor is emphasized.

Human and rodent interferon-gamma as a growth factor for Trypanosoma brucei.

An example for the bidirectional exchange of activating signals between a pathogen and immunocompetent cells in the host is presented. Trypanosoma brucei, which include subspecies that cause African sleeping sickness, secrete a molecule that triggers lymphocytes to produce interferon (IFN)-gamma. We now report that proliferation of T. brucei is stimulated in axenic cultures by IFN-gamma. The growth-enhancing effect on the pathogen is inhibited by anti-IFN-gamma receptor (R) antibodies and does not occur after exposure to other cytokines, i.e. IFN-alpha, IFN-beta and tumor necrosis factor (TNF)-alpha. While rodent-pathogenic T. brucei strains are stimulated by rat IFN-gamma, human pathogenic strains are more potently stimulated by human IFN-gamma. Rat and human IFN-gamma can partially block each others effects. Mice with disrupted IFN-gamma genes have reduced parasitemia and prolonged survival, while the outcome is reversed in mice that lack the IFN-gamma R gene.

Sleeping sickness: perspectives in African trypanosomiasis.

African trypanosomiasis has recently been relegated in the league table of the major infectious diseases. However, in the light of the serious instability of most countries on the African continent, due to civil unrest, political turmoil and unabated fratricidal wars, mass movements of refugees across national borders, to and from sleeping sickness foci, the resurgence and spread of this disease is on the increase. These movements of people en masse are analogous to those which, at the turn of the century led to outbreaks of sleeping sickness killing thousands of people in areas which had previously not experienced this disease. The present situation is compounded by severe budgetary constraints and lack of human resources, making it virtually impossible to undertake surveillance programmes and to deliver health services to already destabilished populations. Current molecular and biochemical studies on the African trypanosome suggest a need for reappraisal of strategies for the diagnosis and treatment of both the chronic and acute forms of sleeping sickness. These studies have also highlighted the complexity of animal trypanosomiasis (nagana). There is an urgent need to understand first, fundamental elements of protection by the immune system, especially in the light of recent findings on the interaction(s), at the outset, between T-cell subsets, B cells, cytokines and parasites and/or parasite derived components (trypanokines), and second, the mechanisms of action of the drugs currently used.