Multiple daily fractionation radiotherapy schedules in lung cancer

Lung cancer is the number one worldwide cancer killer, and in spite of therapeutic advances, the overall impact on survival has remained very modest. For both small and non-small-cell lung cancer, treatment trends have shifted toward combined-modality approaches, chemotherapy for the control of systemic micrometastases, and radiotherapy for intrathoracic control. However, on both counts, rates of failure remain unacceptably high, and several novel strategies are currently being explored. The use of altered fractionation, including multiple daily fractions, reflects one approach for modifying radiotherapy. The two most common approaches are hyperfractionation and acceleration, the former designed to reduce late normal tissue toxicities and the latter to counteract accelerated tumor repopulation. Recent randomized trials suggest that such approaches may result not only in lowered rates of intrathoracic failure but also in improved survival.

Genetic study of oxygen resistance and melanization in Cryptococcus neoformans

Genetic analysis of oxygen-sensitive mutants of Cryptococcus neoformans revealed two loci (oxy1 and oxy2) linking hyperoxia sensitivity to production of melanin, a known virulence factor. Hyperoxia-sensitive strain 562 (oxy1 oxy2) is albino and avirulent. oxy2-defective strains lacking the oxy1 defect are melanin deficient but show normal hyperoxia resistance. Mutants defective at three additional mapped melanin loci fail to show hyperoxia sensitivity in the oxy1 background. Revertants of strain 562, which regain the ability to synthesize melanin by mutation at suppressor sites unlinked to oxy2, retain the oxygen sensitivity conferred by their oxy1 and oxy2 defects. These data identify the melanin gene oxy2 as unique in its association of hyperoxia resistance and melanization.

Responses to cAMP depend on stage of neuronal differentiation of NGF-treated adrenal chromaffin cells

The nerve growth factor (NGF)-dependent transdifferentiation of adrenal chromaffin cells into sympathetic neurons occurs in two sequential phases: The first phase, in which cells extend neurites and increase proliferation, is mimicked by phorbol myristate acetate (PMA), an activator of protein kinase C. Analogs of cAMP, and forskolin, an activator of adenylate cyclase, antagonize the early effects of both NGF and PMA. The second phase of transdifferentiation, in which cells withdraw from the mitotic cycle and express a true neuronal phenotype, occurs after about 2 weeks of exposure to NGF and is neither mimicked by PMA alone nor antagonized by cAMP. Rather, cAMP promotes the neuronal phenotype of cells previously exposed to NGF or PMA. Thus NGF appears to activate different second messenger systems depending on the stage of differentiation of its target cells.

A primary cell culture system of luteinizing hormone releasing hormone neurons derived from embryonic olfactory placode in the rhesus monkey

The purpose of this study is to establish a primary LHRH cell culture system using embryonic olfactory placode and to examine whether LHRH cells derived from olfactory placode and the migratory pathway of LHRH neurons mature in vitro. Six monkey fetuses at the ages of E34-E36 were delivered surgically and the area including the olfactory placode (PL) and the areas that encompass the migratory pathway (MP) were dissected out. The tissues were cut into small pieces and plated on collagen- or poly-L-lysine-coated glass coverslips in medium M199. Cultures were maintained for up to 33 days and immunostained for LHRH, GnRH-associated peptide, neurofilament protein, neuron-specific enolase, and glial fibrillary acidic protein. LHRH positive cells were also positive for neurofilament proteins neuron-specific enolase, and GnRH-associated peptides, but negative for glial fibrillary acidic protein. In the first week of culture, LHRH cells remained within the explants of PL, were rounded (average dimensions: 13.0 x 11.3 microns) and stained lightly. By the second week a number of LHRH cells (15.7 x 13.6 microns) with neurites started to migrate out from PL explants, whereas some still remained in the PL. By the third week a large number of LHRH cells (19.3 x 9.4 microns) had migrated out from the PL. They were fusiform in shape with clear nuclei and extended long varicose neurites up to 500 microns in length. A few "pioneer" LHRH cells appeared to lead the migration of 100-400 LHRH cells forming 1-3 major migratory paths. In contrast, LHRH cells from MP explants migrated out sooner than those from PL explants. LHRH cells from the ventral part of the MP, which is close to the PL, migrated out by 1-2 weeks and formed several migratory paths, whereas LHRH cells from the dorsal part of the MP, which is farther from the PL, were scattered widely around explants and their neurites were extended tortuously. Cultured LHRH cells released LHRH into the media and responded to challenge with high K+. The results indicate that 1) primary LHRH neurons can be obtained from the embryonic PL and their migratory pathway, 2) these neurons migrate and mature in culture and 3) they are accessible for cellular and molecular studies.

HIPIN--a generic HIS/RIS-PACS interface based on clinical radiodiagnostic procedures

Within the EurIPACS HIPIN topic a generic HIS/RIS-PACS interface will be designed, implemented and evaluated. It is generally agreed that integration with the HIS/RIS is essential for the acceptance of PACS in a clinical environment. An interface between HIS/RIS and PACS allows more efficient usage of both systems, better integration of data, better consistency checking on shared data and better security and error handling. Also the PACS performance is improved by using HIS/RIS information to steer the image migration within the PACS. In this paper the functional specifications of the interface are described. These specifications are based on descriptions of clinical radiodiagnostic procedures. The generic interface consists of a common part, and of site specific adapters. The common part is identical for all incarnations and performs message scheduling, processing and logging. The adapters are specific for each communication standard, e.g. ACR-NEMA or HL7, and for each hospital. The interface will be implemented at the radiology department of the Philipps University Hospital in Marburg (Germany) and at the orthopaedic and neuroradiology departments of the hospital of the Free University in Brussels (Belgium).

Effects of NGF and glucocorticoid on NGF receptor immunolabeling of cultured rhesus adrenal chromaffin cells

Nerve growth factor (NGF) promotes the outgrowth of neurites from cultured adrenal chromaffin cells from adult rhesus monkeys, but little is known about the distribution, at the cellular level, of the NGF receptors (NGFR) responsible for this response. We examined changes in immunostaining for NGFR in chromaffin cells cultured for 4 weeks in the presence or absence of NGF, with or without dexamethasone (DEX), which inhibits neuritic outgrowth from these cells. Purified cultures of adrenal chromaffin cells from adult rhesus monkeys were grown for up to 9 weeks in NGF, DEX, NGF plus DEX, or control medium. Cells were immunolabeled with three different monoclonal antibodies directed against different epitopes of the human NGFR. Although the distribution of immunolabeling was not uniform from cell to cell, the overall intensity of NGFR immunolabeling varied dramatically between different growth conditions. Of greatest interest, DEX-treated cells stained the most intensely at all time points, while the intensity of immunolabeling was much fainter in NGF-treated cells and decreased with time in culture. In contrast to the intensity of labeling, the proportion of chromaffin cells with immunoreactivity increased with time in all treatment groups. Thus, GCs do not appear to antagonize the effects of NGF merely by decreasing the total number of immunoreactive NGFR on the surface of these cells.

Early and late effects of NGF may be mediated by different pathways in transdifferentiating chromaffin cells

Nerve growth factor (NGF) causes cultured adrenal chromaffin cells to extend neurites and, after about two weeks of exposure, to 'transdifferentiate' into mature sympathetic neurons. The molecular events leading to these responses are not fully understood, but one possible mediator of NGF's actions is protein kinase C (PKC), which can be directly activated by phorbol esters, including phorbol myristate acetate (PMA). Chronic exposure to PMA mimics the early effects of NGF, that is, it elicits the outgrowth of neurites and an enhanced rate of proliferation. However, while the initial responses to NGF and PMA are similar, after 10 days in culture striking differences become apparent: (1) cells in PMA fail to differentiate into sympathetic neuron-like cells and appear to remain in a transitional state. Even after more than 5 weeks in PMA, cells appear morphologically the same as those grown in PMA for only one week; cells fail to form a dense neuritic network or to exhibit the somatic hypertrophy characteristic of sympathetic neurons. (2) Cells continue to proliferate for at least 4 weeks in PMA, while cells in NGF become postmitotic after about two weeks. (3) While NGF supports and causes the further neuronal differentiation of cells grown in PMA, PMA cannot support NGF-dependent cells. These results suggest that different second messenger systems may be operating in the early and late effects of NGF.

Chronic exposure to an activator of protein kinase C mimics early effects of NGF in chromaffin cells

Adrenal chromaffin cells respond to nerve growth factor (NGF) in vitro by expressing neuronal characteristics and, over a period of 2 to 4 weeks, transdifferentiating into postmitotic sympathetic neurons. Phorbol myristate acetate (PMA) is a potent activator of protein kinase C (PKC); chronic exposure to PMA mimics the initial actions of NGF by promoting the outgrowth of neurites and increasing the incorporation of [3H] thymidine in primary cultures of adrenal chromaffin cells from young rats. PMA and NGF affect the same populations of cells and even individual neurites. These effects are specific for active phorbol ester and do not result from the release of NGF or FGF in the cultures. As in the case of NGF, the effects are inhibited by glucocorticoids. The PKC inhibitor staurosporine inhibits the effects of PMA, as well as those of NGF, in a dose-dependent manner. These results suggest that a modulation in activity of PKC is important in the neuritogenic and proliferative effects of NGF, at least for an initial period of approximately 1 week.