The dependence of soot particle ice nucleation ability on its volatile content.

Aviation soot can affect contrail and cirrus cloud formation and impact climate. A product of incomplete combustion, soot particles, are fractal and hydrophobic aggregates comprising carbonaceous spheres with complex physicochemical properties. In the cirrus cloud regime, the surface wettability and pore abundance of soot particles are important determinants for their ice nucleation ability via pore condensation and freezing. In the atmosphere, soot particles can undergo various ageing processes which modify their surface chemistry and porosity, thus acting as ice nucleating particles with varying abilities as a function of ageing. In this study, size-selected soot particles were treated by thermal denuding at 573 K in a pure nitrogen (N2) or synthetic air (N2 + O2) flow and then exposed to varying relative humidity conditions at a fixed temperature in the range from 218 to 243 K, to investigate the role of volatile content in the ice nucleation ability. Both organic-lean and organic-rich propane (C3H8) flame soot particles, as well as two types of commercially available carbon black soot particles with high and low surface wettability, were tested. The size and mass distribution of soot aerosol were monitored during the ice nucleation experiments. Bulk soot samples also prepared in pure N2 or synthetic air environments at 573 K were characterised by thermogravimetric analysis, Fourier transform infrared spectroscopy and dynamic vapour sorption measurements, to reveal the relation between denuding volatile content, associated soot particle property modifications and the ice nucleation ability. Our study shows that thermal denuding induces a change in soot particle porosity playing a dominant role in regulating its ice nucleation via the pore condensation and freezing mechanism. The enrichment in mesopore (2-50 nm) availability may enhance soot ice nucleation. The presence of O2 in the thermal denuding process may introduce new active sites on soot particles for water interaction and increase soot surface wettability. However, these active sites only facilitate soot ice nucleation when mesopore structures are available. We conclude that a change in volatile content modifies both morphological properties and surface chemistry for soot particles, but porosity change plays the dominant role in regulating soot particle ice nucleation ability.

Non-enhancing relapse of a primary CNS lymphoma with multiple diffusion-restricted lesions.

Primary CNS lymphoma (PCNSL) and its variant primary intraocular lymphoma (PIOL) are rare forms of extranodal non-Hodgkin's lymphoma confined to the CNS including the retina and the optical nerve; histologically, most cases are diffuse large B cell lymphomas. PCNSL in immunocompetent patients display typical radiological features on MRI, i.e. intensely and homogeneously enhancing lesions with moderate edema. Here, we report a 52-year-old male with a history of a PIOL and two consecutive intracerebral relapses who presented with dysarthria, dysphagia, and gait ataxia. Gadolinium-enhanced T1 scans were unremarkable but multiple lesions with restricted water diffusivity were seen on diffusion-weighted imaging. Relapse of his PCNSL was secured histologically only on autopsy. The possible etiology of the diffusion-restricted lesions is discussed.

Diffuse leukoencephalopathy and brain edema: unusual presentations of CNS relapse of acute myeloid leukemia.

An isolated CNS relapse is rarely seen in acute myeloid leukemia. However, it has a potentially fatal clinical outcome. We herein present the case of a 39-year-old man, who presented to our emergency room with horizontal diplopic images, vertigo, bilateral deafness, and progressing somnolence. Cerebral imaging revealed cerebral and cerebellar edema and a diffuse leukoencephalopathy. With the one-year-old history of an initially successfully treated FAB-M0 acute myeloid leukemia (AML) in mind, a lumbar puncture was carried out that showed a vast number of myeloid blasts in the morphologic analysis of the cerebrospinal fluid. In conjunction with normal findings in the peripheral blood-count with differential and the bone marrow examination a diagnosis of an isolated CNS relapse of the AML was made. Cytarabine chemotherapy was initiated and the symptoms resolved rapidly. To our surprise, cerebral imaging in the course of the treatment not only showed a resolution of the brain edema but also of the leukoencephalopathy, pointing to a direct infiltration of brain parenchyma by leukemic blasts. The case highlights the relevance of the CNS as a pharmacologic "sanctuary" for tumor cells in patients that on prior treatments have not received intrathecal chemotherapy or chemotherapeutics that cross the blood-brain barrier.

Combined treatment of pediatric high-grade glioma with the oncolytic viral strain MTH-68/H and oral valproic acid.

The case of a 12-year-old boy with anaplastic astrocytoma of the left thalamus is reported. Postoperative irradiation and chemotherapy could not repress tumor progression; therefore, treatment was undertaken with an oncolytic virus, MTH-68/H, an attenuated strain of Newcastle disease virus (NDV), and valproic acid (VPA), an antiepileptic drug, which also has antineoplastic properties. This treatment resulted in a far-reaching regression of the thalamic glioma, but 4 months later a new tumor manifestation, an extension of the thalamic tumor, appeared in the wall of the IVth ventricle, which required a second neurosurgical intervention. Under continuous MTH-68/H - VPA administration the thalamic tumor remained under control, but the rhombencephalic one progressed relentlessly and led to the fatal outcome. In the final stage, a third tumor manifestation appeared in the left temporal lobe. The possible reasons for the antagonistic behavior of the three manifestations of the same type of glioma to the initially most successful therapy are discussed. The comparative histological study of the thalamic and rhombencephalic tumor manifestations revealed that MTH-68/H treatment induces, similar to in vitro observations, a massive apoptotic tumor cell decline. In the rhombencephalic tumor, in and around the declining tumor cells, NDV antigen could be demonstrated immunohistochemically, and virus particles have been found in the cytoplasm of tumor cells at electron microscopic investigation. These findings document that the oncolytic effect of MTH-68/H treatment is the direct consequence of virus presence and replication in the neoplastic cells. This is the first demonstration of NDV constituents in an MTH-68/H -treated glioma.

Conditions of iodine contrast transfer from lumbosacral CSF to blood.

PURPOSE: To determine conditions which influence transfer of iopamidol from lumbosacral cerebrospinal fluid (CSF) to blood. METHODS: Iopamidol transfer was measured in 32 patients over 180 min after radiculography and compared with patient variables. RESULTS: Iopamidol transfer began early in 12 patients, more slowly in 13 patients, and was not detected during sample period in 7 patients. Transfer of sequential samples correlated highly with each other (r>0.8). Transfer was more pronounced in patients with prominent nerve root sleeves on radiculogram (p=0.006, t test), and correlated inversely with body weight (r=-0.4258), and with albumin CSF/serum quotient (r=-0.4702). CONCLUSION: Early iopamidol transfer probably indicates transfer through spinal arachnoid villi and granulations with CSF bulk flow. Prominent nerve root sleeves may facilitate access to transfer sites. No transfer during sample period suggests no such spinal transfer, possibly due to sparse access to or presence of spinal transfer sites. Inverse correlation of transfer with body weight may reflect influence of body weight on retroperitoneal venous pressure, which regulates outflow of CSF and of compounds dissolved in it. Awareness of wide interindividual transfer variation and steady intraindividual transfer may help to specify dosage and effect expectation of intrathecal drug therapy.

Determinants of lumbar CSF protein concentration.

OBJECTIVE: To determine factors influencing the wide variation of protein concentration in lumbar cerebrospinal fluid (CSF). METHODS: Patient variables with potential influence on spinal CSF flow and resorption were measured in different patient settings and compared with albumin and IgG CSF/serum quotients. RESULTS: In patients whose diagnostic lumbar puncture produces normal CSF the albumin quotient increased with body mass index (r = 0.408), abdominal circumference (r = 0.399), and body weight (r = 0.317), age-corrected with partial correlation. Body motion before lumbar puncture showed only marginal influence on albumin quotient. In patients with radiculography the albumin quotient decreased with iodine contrast medium elimination from spinal subarachnoid space (r = -0.598) and increased with narrowing of lumbosacral spinal canal (r = 0.515). CONCLUSION: Correlation of albumin quotient with body mass index and related variables may be mediated by spinal CSF resorption, which should be impaired in overweight patients with elevated venous pressure. Negative correlation of albumin quotient with iodine resorption from spinal CSF supports this assumption. Correlation of albumin quotient with narrowing of lumbosacral canal should be due to slowed spinal CSF flow which does increase protein concentration. Tested variables explain part of variation of CSF protein concentration. Other variables like blood-CSF barrier permeability and pulsatile spinal CSF flow should have additional influence.