Quantification of mitochondrial cfDNA reveals new perspectives for early diagnosis of colorectal cancer

BACKGROUND

To unravel how the integrity of nuclear and mitochondrial circulating cell-free DNA (cfDNA) contributes to its plasma quantity in colorectal cancer (CRC) patients.

METHODS

CfDNA from plasma samples of 80 CRC patients stratified by tumour stage and 50 healthy individuals were extracted. Total cfDNA concentration was determined and equal template concentrations (ETC) were analyzed by quantitative real-time PCR (qPCR) resulting in small and long fragments of KRAS, Alu and MTCO3. The obtained data was also examined relative to the total cfDNA concentration (NTC) and diagnostic accuracy was estimated using receiver operating characteristics.

RESULTS

Total cfDNA levels were significantly higher in CRC group compared to healthy control and increased with tumour stage. Long nuclear fragment levels were significantly lower in CRC patients in ETC but not NTC condition. The integrity indices of nuclear cfDNA decreased from controls to patients with highly malignant tumor. Mitochondrial cfDNA fragment quantities were strongly reduced in early and late stages of tumor patients and prognostic value was higher in ETC. Predictive models based on either ETC or NTC predictor set showed comparable classification performance.

CONCLUSION

Increased blood cfDNA concentration in late UICC stages inversely correlate with nuclear cfDNA integrity index and suggest that necrotic degradation is not a major cause for higher total cfDNA quantity. The diagnostic and prognostic value of MTCO3 is highly significant in early stages of CRC and can be evaluated more comprehensively, using ETC for qPCR analysis.

TRIAL REGISTRATION

The study was registered retrospectively on DRKS, the german register for clinical trials (DRKS00030257, 29/09/2022).

P11.53.B Efficacy and tolerability of regorafenib in pretreated patients with progressive CNS grade 3 or 4 gliomas

Background

The phase 2 REGOMA trial suggested an encouraging overall survival benefit in glioblastoma patients at first relapse treated with the multikinase inhibitor regorafenib. Here, we evaluated the efficacy and side effects of regorafenib in a real-life setting.

Material and Methods

From 2018-2021, 30 patients with progressive WHO CNS grade 3 or 4 gliomas treated with regorafenib (160 mg/d; first 3 weeks of each 4-week cycle) with individual dose adjustment depending on toxicity were retrospectively identified. Side effects were evaluated according to the Common Terminology Criteria for Adverse Events (version 5.0). MRI was obtained at baseline and after every second cycle. Tumor progression was assessed according to RANO criteria. After regorafenib initiation, the median progression-free survival (PFS) and overall survival (OS) were calculated.

Results

The median number of treatment lines before regorafenib was 2 (range, 1-4). The majority of patients (73%) had two or more pretreatment lines. At first relapse, 27% of patients received regorafenib. A total of 94 regorafenib cycles were administered (median number of cycles, 2; range, 1-9 cycles). Grade 3 and 4 side effects were observed in 47% and 7% of patients, respectively, and were not significantly increased in patients with two or more pretreatments (P>0.05). The most frequent grade 3 or 4 side effects were laboratory abnormalities (62%). PFS was 2.6 months (range, 0.8-8.2 months), and the OS was 6.2 months (range, 0.9-24 months).

Conclusion

In patients with progressive WHO grade 3 or 4 gliomas, predominantly with two pretreatment lines or more, regorafenib seems to be effective despite considerable grade 3 or 4 side effects.

KS02.7.A Impact of FET PET on multidisciplinary neurooncological tumor board decisions in patients with brain tumors

Background

Following neurooncological treatment of brain tumors, neurooncologists are often confronted with equivocal MRI findings (e.g., treatment-related changes such as pseudoprogression, non-measurable contrast-enhancing lesions, T2/FLAIR signal alterations, pseudoresponse). Especially in Europe, amino-acid PET is increasingly integrated into multidisciplinary neurooncological tumor boards (MNTB) to overcome these diagnostic uncertainties. We evaluated the correctness of MNTB decisions, in which amino acid PET findings were taken into account.

Material and Methods

In a single-university center study, we retrospectively evaluated 182 MNTB decisions of 154 patients with histomolecularly defined WHO grade 3 or 4 gliomas (n=123), including glioblastoma (n=80), anaplastic glioma (n=42), and gliosarcoma (n=1), or brain metastases (n=31) secondary to lung cancer, melanoma, breast cancer, or colorectal cancer presenting equivocal MRI findings following anticancer treatment. All patients underwent O-(2-[18F]-fluoroethyl)-L-tyrosine (FET) PET imaging as an adjunct for decision-making. Additionally, the patients’ clinical status, pretreatment, and conventional MRI findings were considered for decision-making. The presence of neoplastic tissue was considered if the mean FET uptake as assessed by tumor-to-brain ratios was > 2.0. MNTB decisions were validated using the neuropathological result in 42% (n=77) or clinicoradiologically in 58% (n=105). The diagnostic performance of MTNB decisions was evaluated using 2x2 contingency tables.

Results

The validation of all 182 MNTB recommendations, which integrated FET PET in the decision-making process, were correct in 95% (sensitivity, 97%; specificity, 75%; positive predictive value, 96%). Due to tumor progression, MNTB recommendations prompted a treatment change in 88% (n=160 of 182 decisions). When FET PET findings suggested progressive disease (n=157), MNTB decisions were correct in 96% (positive predictive value, 97%). In 22 MNTB decisions with the recommendation to continue the current treatment regimen, 82% were correctly identified as treatment-related changes.

Conclusion

FET PET seems to have a significant impact on MNTB decisions. A prospective evaluation of MNTB decisions with and without the integration of FET PET is warranted to define the added value of FET PET.

P14.79 Differentiation of treatment-related changes from tumor progression following brachytherapy in patients with WHO II and III gliomas using FET PET

BACKGROUND

Following brachytherapy, the differentiation of radiation-induced changes (e.g., radiation necrosis) from actual tumor progression using MRI is challenging. To overcome this diagnostic uncertainty, we evaluated the diagnostic value of O-(2-[18F]-fluoroethyl)-L-tyrosine (FET) PET in glioma patients treated with brachytherapy.

MATERIAL AND METHODS

From 2006–2019, we retrospectively identified WHO grade II or III glioma patients (i) treated with brachytherapy using Iodine-125 seeds, (ii) equivocal or progressive MRI findings inside the radiation field, and (iii) additional FET PET imaging for diagnostic evaluation. Static FET PET parameters such as maximum and mean tumor-to-brain ratios (TBR) and dynamic FET PET parameters (i.e., time-to-peak, slope) were obtained. Diagnostic performances were calculated using receiver operating characteristic curve analyses and Fisher’s exact test. Diagnoses were confirmed histologically or clinicoradiologically.

RESULTS

Following brachytherapy, suspect MRI findings occurred after a median time of 33 months (range, 5–111 months). In 10 of 21 patients (WHO grade II, n=5; WHO grade III, n=16), treatment-related changes were diagnosed. The best diagnostic performance for identification of treatment-related changes was obtained using maximum TBRs (threshold <3.20; accuracy, 86%; sensitivity, 100%; specificity, 73%; P=0.007). Mean TBRs reached an accuracy of 76% (threshold <2.05; sensitivity, 89%; specificity, 64%; P=0.010). Dynamic PET parameters did not reach statistically significant results.

CONCLUSION

Our data suggest that static FET PET parameters add valuable diagnostic information to diagnose radiation-induced changes in glioma patients treated with brachytherapy.

Statistical inference in abstracts of three influential clinical pharmacology journals analyzed using a text-mining algorithm

AIM

To describe the trend in the prevalence of statistical inference in three influential clinical pharmacology journals METHODS: We applied a computer-based algorithm to abstracts of three clinical pharmacology journals published in 1976 to 2016 to identify statistical inference and its subtypes. Furthermore, we manually reviewed a random sample of 300 articles to access algorithm's performance in finding statistical inference in abstracts and as a screening tool for presence and absence of statistical inference in full text.

RESULT

The algorithm identified 59% (13,375/22,516 [mid p 95% CI, 59%-60%]) article abstracts with statistical inference. The percentage of abstracts with statistical inference was similar in 1976 and 2016, 48% (179/377 [mid p 95%CI, 42%-52%]) versus 49% (386/791 [mid p 95%CI, 45%-52%]). Statistical reporting pattern varied among journals. Among abstracts containing any statistical inference in the publications from 1976 to 2016 null-hypothesis significance testing was the most prevalent reported statistical inference. The algorithm had high sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for finding statistical inferences in abstract. While PPV for predicting the statistical inference in full text (including abstract, text, tables and figures) was high, NPV was low.

CONCLUSION

Despite journal's editorials and statistical associations' guidelines, most authors focused on testing rather than estimation. In future, a better statistical reporting might be ensured by improving the statistical knowledge of authors and an addition of statistical guides to journals' instruction to authors to the extent that editors would like their statistical inference preferences to be incorporated into submitted manuscripts.

Statistical Inference in Abstracts Published in Cardiovascular Journals

BACKGROUND

In 2016, the American Statistical Association stated that the use of statistical significance leads to distortion of the scientific process. The principal alternative to significance or null hypothesis testing (NHT) is estimation with point estimates and confidence intervals (CIs).

OBJECTIVES

The aim of this study was to determine the time trend of statistical inference and statistical reporting style in abstracts in major cardiovascular journals.

METHODS

A total of 84,250 abstracts published from 1975 to 2019 in 9 high-ranking cardiovascular journals (Circulation, Circulation Research, European Heart Journal, European Heart Journal: Cardiovascular Imaging, European Journal of Heart Failure, Journal of the American College of Cardiology, JACC: Cardiovascular Imaging, JACC: Cardiovascular Interventions, and JAMA Cardiology) were reviewed; in particular, proportions of abstracts containing statistical inference and its major variants (NHT, significance testing) were compared over time and among journals.

RESULTS

Overall, 49,924 abstracts (59%) contained statistical inference. Among these abstracts, NHT was the most frequent reporting style of statistical inference (79% among all journals). Journals differed considerably in the prevalence of CI reporting (1% to 78% in 2017-2019). With the exception of 2 journals, the proportion of abstracts containing CIs was higher in the more recent period. From 2013-2015 to 2017-2019, the proportion of abstracts containing only CIs increased by 5 (95% CI: 0 to 10), 18 (95% CI: 15 to 21), and 9 (95% CI: 3 to 15) percentage points in the European Heart Journal, the Journal of the American College of Cardiology, and JACC: Cardiovascular Imaging, respectively.

CONCLUSIONS

NHT is still the prevailing reporting style of statistical inference in major cardiovascular journals. Reporting of CIs in abstracts of major cardiovascular journals appears to be growing more popular.

Diffuse glioneuronal tumour with oligodendroglioma-like features and nuclear clusters (DGONC) - a molecularly defined glioneuronal CNS tumour class displaying recurrent monosomy 14

AIMS

DNA methylation-based central nervous system (CNS) tumour classification has identified numerous molecularly distinct tumour types, and clinically relevant subgroups among known CNS tumour entities that were previously thought to represent homogeneous diseases. Our study aimed at characterizing a novel, molecularly defined variant of glioneuronal CNS tumour.

PATIENTS AND METHODS

DNA methylation profiling was performed using the Infinium MethylationEPIC or 450 k BeadChip arrays (Illumina) and analysed using the 'conumee' package in R computing environment. Additional gene panel sequencing was also performed. Tumour samples were collected at the German Cancer Research Centre (DKFZ) and provided by multinational collaborators. Histological sections were also collected and independently reviewed.

RESULTS

Genome-wide DNA methylation data from >25 000 CNS tumours were screened for clusters separated from established DNA methylation classes, revealing a novel group comprising 31 tumours, mainly found in paediatric patients. This DNA methylation-defined variant of low-grade CNS tumours with glioneuronal differentiation displays recurrent monosomy 14, nuclear clusters within a morphology that is otherwise reminiscent of oligodendroglioma and other established entities with clear cell histology, and a lack of genetic alterations commonly observed in other (paediatric) glioneuronal entities.

CONCLUSIONS

DNA methylation-based tumour classification is an objective method of assessing tumour origins, which may aid in diagnosis, especially for atypical cases. With increasing sample size, methylation analysis allows for the identification of rare, putative new tumour entities, which are currently not recognized by the WHO classification. Our study revealed the existence of a DNA methylation-defined class of low-grade glioneuronal tumours with recurrent monosomy 14, oligodendroglioma-like features and nuclear clusters.

[Increasing Mortality from Cardiac Arrhythmia in Germany?]

BACKGROUND

The 'Deutscher Herzbericht 2016' [German Heart Report] reported a strongly increasing mortality rate from cardiac arrhythmia in Germany from 1990 to 2014. The increase was higher in women than in men and was rated as 'paradoxical' in light of improved diagnostic and therapeutic procedures. The aim of this paper is to explore the mortality data for cardiac arrhythmias in detail and to generate an explanatory approach.

METHODS

We extracted the number of deaths from cardiac arrhythmia (ICD-10 codes I44-I49) for each sex, 5-year-age group and each federal state for 2000-2014 (www.gbe-bund.de). Crude as well as age-specific and age-standardized (standard: Germany census 2011) mortality rates were calculated.

RESULTS

While the crude mortality rates increased considerably between 2000 and 2014 (men: 18 to 26, women: 23 to 38 pro 100,000), the age-standardized mortality rates showed only a small increase (men: 31 to 32, women: 22 to 27 per 100,000 person years). This increase was attributable to an increasing mortality rate from atrial fibrillation and flutter (ICD-10: I48) in men and women aged 80 years and older. In younger age groups and in other subgroups of cardiac arrhythmia, no relevant increases were seen.

CONCLUSION

The increase of mortality rates from cardiac arrhythmia as reported in 'Deutscher Herzbericht 2016' is largely attributable to the demographic changes in the German population. After age-standardization, there still remains an increase in the mortality rates, but this is smaller. From an epidemiologic perspective, it is a common problem in the interpretation involving crude mortality data. Moreover, the validity of mortality rates for cardiac arrhythmia is limited due to several reasons.

Cancer cell-derived long pentraxin 3 (PTX3) promotes melanoma migration through a toll-like receptor 4 (TLR4)/NF-κB signaling pathway

Cutaneous melanoma is one of the most aggressive cancers characterized by a high plasticity, a propensity for metastasis, and drug resistance. Melanomas are composed of phenotypically diverse subpopulations of tumor cells with heterogeneous molecular profiles that reflect intrinsic invasive abilities. In an attempt to identify novel factors of the melanoma invasive cell state, we previously investigated the nature of the invasive secretome by using a comparative proteomic approach. Here, we have extended this analysis to show that PTX3, an acute phase inflammatory glycoprotein, is one such factor secreted by invasive melanoma to promote tumor cell invasiveness. Elevated PTX3 production was observed in the population of MITFlow invasive cells but not in the population of MITFhigh differentiated melanoma cells. Consistently, MITF knockdown increased PTX3 expression in MITFhigh proliferative and poorly invasive cells. High levels of PTX3 were found in tissues and blood of metastatic melanoma patients, and in BRAF inhibitor-resistant melanoma cells displaying a mesenchymal invasive MITFlow phenotype. Genetic silencing of PTX3 in invasive melanoma cells dramatically impaired migration and invasion in vitro and in experimental lung extravasation assay in xenografted mice. In contrast, addition of melanoma-derived or recombinant PTX3, or expression of PTX3 enhanced motility of low migratory cells. Mechanistically, autocrine production of PTX3 by melanoma cells triggered an IKK/NFκB signaling pathway that promotes migration, invasion, and expression of the EMT factor TWIST1. Finally, we found that TLR4 and MYD88 knockdown inhibited PTX3-induced melanoma cell migration, suggesting that PTX3 functions through a TLR4-dependent pathway. Our work reveals that tumor-derived PTX3 contributes to melanoma cell invasion via targetable inflammation-related pathways. In addition to providing new insights into the biology of melanoma invasive behavior, this study underscores the notion that secreted PTX3 represents a potential biomarker and therapeutic target in a subpopulation of MITFlow invasive and/or refractory melanoma.

Tracing scientific reasoning in psychiatry: Reporting of statistical inference in abstracts of top journals 1975-2015

OBJECTIVE

To analyze the reporting of statistical inference in psychiatry.

METHOD

We searched 63,928 abstracts, published in 15 leading psychiatric journals (1975-2015).

RESULTS

Median abstract length increased from 664 (1975) to 1,323 (2015) characters, and median use of numbers from two to 14/abstract. A total of 3.6% of all abstracts exclusively contained significance terminology in a nonstatistical sense, and 45% showed some form of statistical inference, increasing from 26% to 52%. In those abstracts, statistical inference based on thresholds was dominant. Its proportion decreased from 99% to 66%, but with rising numbers of articles, figures rose from 1,095 to 2,382. Although reporting p values without thresholds did not appear 40 years ago and remains rare, combining precise p values with thresholds is now common. In 2010-2015, 86% of abstracts contained p values or p value thresholds, 22% confidence intervals, and 7% confidence intervals only. Results varied across journals.

CONCLUSION

There is a moderate shift from reporting p values along set thresholds, such as p ≤ 0.05, to presenting precise p values and confidence intervals, but not as pronounced as in epidemiology and general medicine. The long debate on estimation over testing has not led to a substantial replacement of p values by confidence intervals. Null hypothesis testing ("p ≤ .05") dominates statistical thinking.

Differential effects of CXCR4-CXCL12- and CXCR7-CXCL12-mediated immune reactions on murine P0106-125 -induced experimental autoimmune neuritis

AIM

The role of chemokines and their receptors, which regulate trafficking and homing of leucocytes to inflamed organs in human or murine autoimmune neuritis, has not yet been elucidated in detail, Therefore, the role of the chemokine receptors CXCR4 and CXCR7 and their ligand CXCL12 was studied in autoimmune-mediated inflammation of the peripheral nervous system.

METHODS

CXCL12/CXCR4 and/or CXCL12/CXCR7 interactions were specifically inhibited by the compounds AMD3100 or CCX771, respectively, in experimental autoimmune neuritis (EAN) of C57BL/6J mice immunized with P0106-125 peptide.

RESULTS

Disease activity was significantly suppressed by blocking CXCR7 while antagonization of CXCR4 enhanced disease activity. Enhanced disease activity was accompanied by significantly increased transcription of IFN-γ, IL-12 and TNF-α mRNA in regional lymph nodes and spleen as well as by increased serum levels of IFN-γ. Furthermore, by blocking CXCR4, expression of the cell adhesion molecules ICAM-1 and VCAM-1 was upregulated on vascular endothelial cells of the sciatic nerve, which coincided with significantly increased infiltration of the sciatic nerve by CD4+ T cells and macrophages. Remarkably, combined antagonization of both CXCR4 and CXCR7 significantly suppressed disease activity. This was accompanied by increased frequencies of activated and highly IFN-γ-expressing, P0106-125 -specific T cells in regional lymph nodes and spleen; however, these cells were unable to infiltrate the sciatic nerve.

CONCLUSION

These data suggest differential and hierarchically ordered roles for CXCR4/CXCL12- vs. CXCR7/CXCL12-dependent effects during EAN: CXCR7/CXCL12 interaction is a gatekeeper for pathogenic cells, regardless of their CXCR4/CXCL12-dependent state of activation.

Modern concepts in the biology, diagnosis, differential diagnosis and treatment of primary central nervous system lymphoma

Recent studies addressing the molecular characteristics of PCNSL, which is defined as malignant B-cell lymphoma with morphological features of DLBCL, have significantly improved our understanding of the pathogenesis of this lymphoma entity, which is associated with an inferior prognosis as compared with DLBCL outside the CNS. This unfavorable prognosis stimulated intense efforts to improve therapy and induced recent series of clinical studies, which addressed the role of radiotherapy and various chemotherapeutic regimens. This review combines the discussion of diagnosis, differential diagnosis and recent progress in studies addressing the molecular pathogenesis as well as therapeutic options in PCNSL.

Ciglitazone negatively regulates CXCL1 signaling through MITF to suppress melanoma growth

We have previously demonstrated that the thiazolidinedione ciglitazone inhibited, independently of PPARγ activation, melanoma cell growth. Further investigations now show that ciglitazone effects are mediated through the regulation of secreted factors. Q-PCR screening of several genes involved in melanoma biology reveals that ciglitazone inhibits expression of the CXCL1 chemokine gene. CXCL1 is overexpressed in melanoma and contributes to tumorigenicity. We show that ciglitazone induces a diminution of CXCL1 level in different human melanoma cell lines. This effect is mediated by the downregulation of microphthalmia-associated transcription factor, MITF, the master gene in melanocyte differentiation and involved in melanoma development. Further, recombinant CXCL1 protein is sufficient to abrogate thiazolidinedione effects such as apoptosis induction, whereas extinction of the CXCL1 pathway mimics phenotypic changes observed in response to ciglitazone. Finally, inhibition of human melanoma tumor development in nude mice treated with ciglitazone is associated with a strong decrease in MITF and CXCL1 levels. Our results show that anti-melanoma effects of thiazolidinediones involve an inhibition of the MITF/CXCL1 axis and highlight the key role of this specific pathway in melanoma malignancy.

Chromosomal imbalances and partial uniparental disomies in primary central nervous system lymphoma

To determine the pattern of genetic alterations in primary central nervous system lymphomas (PCNSL), 19 PCNSL were studied by high-density single-nucleotide polymorphism arrays. Recurrent losses involved 6p21.32, 6q21, 8q12-12.2, 9p21.3, 3p14.2, 4q35.2, 10q23.21 and 12p13.2, whereas gains involved 18q21-23, 19q13.31, 19q13.43 and the entire chromosomes X and 12. Partial uniparental disomies (pUPDs) were identified in 6p and 9p21.3. These genomic alterations affected the HLA locus, the CDKN2A/p16, CDKN2B/p15 and MTAP, as well as the PRDM1, FAS, MALT1, and BCL2 genes. Increased methylation values of the CDKN2A/p16 promoter region were detected in 75% (6/8) PCNSL. Gene expression profiling showed 4/21 (20%) minimal common regions of imbalances to be associated with a differential mRNA expression affecting the FAS, STAT6, CD27, ARHGEF6 and SEPT6 genes. Collectively, this study unraveled novel genomic imbalances and pUPD with a high resolution in PCNSL and identified target genes of potential relevance in the pathogenesis of this lymphoma entity.

Involvement of FKHRL1 in melanoma cell survival and death

Melanoma is a highly aggressive tumour characterized by a strong resistance to apoptotic stimuli that give rise to a selective advantage for tumour progression and metastasis formation. Therefore, it is of paramount importance to better understand the mechanisms involved in this resistance to apoptosis. In this report, we focused our attention on FKHRL1, a member of the forkhead family of transcription factors, which controls expression of genes involved in cell cycle progression and apoptosis. In melanoma cells, we show that IGF1, which exerts pro-survival properties, induces the phosphorylation and nuclear exclusion of FKHRL1 in a PI3K/AKT-dependent pathway. Moreover, we observe that over-expression of a non-phosphorylable mutant of FKHRL1 (FKHRL1-TM), constitutively localized to the nucleus, promotes apoptotic cell death of melanoma cells. Finally, we find that FKHRL1-TM decreases the expression of survivin, a member of the inhibitor of apoptosis protein and that survivin re-expression partially rescues the deleterious effects of FKHRL1. Taken together, these findings reveal, in melanoma cells, that endogenous FKHRL1 is a downstream target of the PI3K/AKT pathway and suggest that the phosphorylation of this transcription factor may be involved in the pro-survival effects of growth factors such as IGF1. On the other hand, forced nuclear localization of FKHRL1 decreases melanoma cell growth and may serve as a therapeutic strategy against melanoma.

High-dose methotrexate combined with procarbazine and CCNU for primary CNS lymphoma in the elderly: results of a prospective pilot and phase II study

BACKGROUND

To improve survival of elderly patients with primary central nervous system lymphoma (PCNSL), we conducted a phase II study with high-dose methotrexate (MTX) combined with procarbazine and CCNU. To reduce neurotoxicity, whole-brain irradiation was reserved for patients not responding to chemotherapy.

PATIENTS AND METHODS

High-dose MTX was applied on days 1, 15, and 30, procarbazine on days 1-10, and CCNU on day 1. Study treatment comprised up to three 45-day cycles. There was no lower limit of Karnofsky performance status (KPS).

RESULTS

Thirty patients with PCNSL (n = 29) or primary ocular lymphoma (n = 1) were included (median age 70 years, range 57-79 years). The median initial KPS was 60% (range 30%-90%). Best documented response in 27 assessable patients were 12 of 27 (44.4%) complete remissions, 7 of 27 (25.9%) partial remissions, and 8 of 27 (29.6%) disease progressions. Two patients died of probable treatment-related causes. With a median follow-up of 78 months (range 34-105), the 5-year overall survival is 33%. Eight of 30 patients (26.7%) are currently alive and well, six without signs of leukoencephalopathy.

CONCLUSION

The combination of high-dose MTX with procarbazine and CCNU is feasible and effective and results in a low rate of leukoencephalopathy. Comorbidity and toxicity remain of concern when treating PCNSL in elderly patients.

Gene expression profiling suggests primary central nervous system lymphomas to be derived from a late germinal center B cell

To characterize the molecular origin of primary lymphomas of the central nervous system (PCNSL), 21 PCNSLs of immunocompetent patients were investigated by microarray-based gene expression profiling. Comparison of the transcriptional profile of PCNSL with various normal and neoplastic B-cell subsets demonstrated PCNSL (i) to display gene expression patterns most closely related to late germinal center B cells, (ii) to display a gene expression profile similar to systemic diffuse large B-cell lymphomas (DLBCLs) and (iii) to be in part assigned to the activated B-cell-like (ABC) or the germinal center B-cell-like (GCB) subtype of DLBCL.

Homeostatic chemokines increase survival of B-chronic lymphocytic leukemia cells through inactivation of transcription factor FOXO3a

B-chronic lymphocytic leukemia (B-CLL) cell is characterized by the accumulation of long-lived CD5+ B lymphocytes, whose survival in vivo is in part dependent on exogenous factors such as cytokines and/or extracellular matrix proteins. Homeostatic chemokines are critical mediators of lymphoid cell trafficking. However, how they function in cell signaling and survival remains ill-defined. In this study, we have investigated the role of the homeostatic chemokines, CXCL12, CCL21, CCL19 and CXCL13, in B-CLL cell survival. Using primary leukemic cells isolated from 26 patients, we observed that each chemokine enhances cell survival. Chemokines induced the phosphorylation of ERK1/2 and p90RSK, and of Akt and its effectors GSK3 and FOXO3a. Consistently, inhibitors against mitogen-activated protein kinase/extracellular signal-regulated kinase and phosphatidylinositol 3-kinase inhibited chemokine-induced survival. Moreover, using a constitutively active mutated form of FOXO3a or siRNAs against FOXO3a in transfection experiments performed in primary B-CLL cells, we directly demonstrated the critical role of FOXO3a in both spontaneous and chemokine-induced B-CLL cell survival. Overall, our data support the notion that homeostatic chemokines contribute to B-CLL resistance to cell death through inactivation of the transcription factor FOXO3a, which may represent a novel therapeutic target in this hematopoietic malignancy.

Id3 is a novel regulator of p27kip1 mRNA in early G1 phase and is required for cell-cycle progression

P27kip is a key inhibitory protein of the cell-cycle progression, which is rapidly downregulated in early G1 phase by a post-translational mechanism involving the proteosomal degradation. In this study, using a wounding model that induces cell-cycle entry of human dermal fibroblasts, we demonstrate that p27mRNA is downregulated when cells progress into the G1 phase, and then it returns to its basal level when cells approach the S phase. By using a quantitative polymerase chain reaction screening we identified inhibitors of differentiation (Id3), a bHLH transcriptional repressor, as a candidate mediator accounting for p27 mRNA decrease. Id3 silencing, using an small interfering RNA approach, reversed the injury mediated p27 downregulation demonstrating that Id3 is involved in the transcriptional repression of p27. Reporter gene experiments and a chromatin immunoprecipitation assay showed that Id3 likely exerts its repressive action through ELK1 inhibition. By inhibiting early p27 downregulation, Id3 depletion blocked (i) the G1-phase progression as assessed by the inhibition of pRb phosphorylation and p130 degradation and (ii) the G1/S transition as observed by the inhibition of cyclin A induction, demonstrating that p27 mRNA decrease is required for cell proliferation. Apart from its effect on the early p27 diminution, Id3 appears also involved in the control of the steady-state level of p27 at the G1/S boundary. In conclusion, this study identifies a novel mechanism of p27 regulation which besides p27 protein degradation also implicates a transcriptional mechanism mediated by Id3.

[Primary CNS lymphoma in azathioprine therapy for autoimmune diseases: review of the literature and case report]

We present a 31-year-old female patient with primary non-Hodgkin's lymphoma of the CNS after immunosuppressive therapy. Colitis ulcerosa had been diagnosed 2 years previously. Prophylactic therapy with azathioprine over 9 months was stopped after the development of listeria meningitis which was treated successfully with antibiotics. At this time native CCT was normal. Three months later the patient developed an epileptic seizure and multiple cerebral lesions were detected in CCT and MRI. Although antibiotic therapy was started, the cerebral lesions showed no regression. Stereotactic biopsy revealed immunochemical and histologic high-grade malignant B cell lymphoma. The risk of primary CNS lymphoma under azathioprine treatment for an autoimmune disease with a possible congenital immunodeficiency is presented and the literature is reviewed.

A 43-year-old woman with a temporal mass

A 43-year-old woman with a past medical history of breast cancer and an acute myeloid leukemia (AML) presented with headache over a 3-week period. The clinical examination was completely unremarkable. CT and MRI scans showed a contrast enhancing lesion in the left temporal lobe. Histopathologic examination revealed a malignant, hematopoietic tumor with high mitotic activity, areas of necrosis and diffuse infiltration of the brain parenchyma. Positive staining for Chloroacetateesterase and lysozyme of tumor cells identified its myeloid lineage. The diagnosis was granulocytic sarcoma (GS)/chloroma, a metastatic manifestation of AML. Granulocytic sarcoma (GS) most often occurs in patients with AML, myelodysplastic syndromes and myeloproliferative disorders, and can involve any organ. However intracerebral manifestation of GS is a rare event. In this case histopathological features and differential diagnoses of intracerebral GS are discussed.

A survey of the signaling pathways involved in megakaryocytic differentiation of the human K562 leukemia cell line by molecular and c-DNA array analysis

The K562 cell line serves as a model to study the molecular mechanisms associated with leukemia differentiation. We show here that cotreatment of K562 cells with PMA and low doses of SB202190 (SB), an inhibitor of the p38 MAPK pathway, induced a majority of cells to differentiate towards the megakaryocytic lineage. Electronic microscopy analysis showed that K562 cells treated with PMA+SB exhibited characteristic features of physiological megakaryocytic differentiation including the presence of vacuoles and demarcation membranes. Differentiation was also accompanied by a net increase in megakaryocytic markers and a reduction of erythroid markers, especially when both effectors were present. PMA effect was selectively mediated by new PKC isoforms. Differentiation of K562 cells by the combination of PMA and SB required Erk1/2 activation, a threshold of JNK activation and p38 MAPK inhibition. Interestingly, higher concentrations of SB, which drastically activated JNK, blocked megakaryocytic differentiation, and considerably increased cell death in the presence of PMA. c-DNA microarray membranes and PCR analysis allow us to identify a set of genes modulated during PMA-induced K562 cell differentiation. Several gene families identified in our screening, including ephrins receptors and some angiogenic factors, had never been reported so far to be regulated during megakaryocytic differentiation.

Long-term remission in progressive multifocal leukoencephalopathy caused by idiopathic CD4+ T lymphocytopenia: a case report

Progressive multifocal leukoencephalopathy is caused by JC virus, an opportunistic infection of the central nervous system. Antiretroviral treatment for progressive multifocal leukoencephalopathy in human immunodeficiency virus-infected patients is beneficial, but few data exist for patients who are not infected with human immunodeficiency virus. Idiopathic CD4+ T lymphocytopenia excludes human immunodeficiency virus infection. We describe a patient with progressive multifocal leukoencephalopathy with underlying idiopathic CD4+ T lymphocytopenia in whom functional recovery occurred without antiviral therapy.

The Immunological Synapse and Rho GTPases

Rho GTPases are molecular switches controlling a broad range of cellular processes including lymphocyte activation. Not surprisingly, Rho GTPases are now recognized as pivotal regulators of antigen-specific T cell activation by APCs and immunological synapse formation. This review summarizes recent advances in our understanding of how Rho GTPase-dependent pathways control T lymphocyte motility, polarization and activation.

Clonal evolution as pathogenetic mechanism in relapse of primary CNS lymphoma

Comparative investigation of immunoglobulin (Ig) heavy chain gene rearrangements and DNA sequence analyses of a primary lymphoma of the CNS (PCNSL) and its recurrence revealed that both tumors used the same Ig gene segment. In addition to shared somatic mutations, the primary and the recurrent PCNSLs harbored somatic mutations unique to each tumor. Clonal evolution rather than subclone selection appears to underlie the development of tumor recurrence in this case.

Molecular and functional imaging technology for the development of efficient treatment strategies for gliomas

Gliomas are the most common types of brain tumors, which invariably lead to death over months or years. Before new and potentially more effective treatment strategies, such as gene therapy, can be effectively introduced into clinical application the following goals must be reached: (1) the determination of localization, extent and metabolic activity of the glioma; (2) the assessment of functional changes within the surrounding brain tissue; (3) the identification of genetic changes on the molecular level leading to disease; and in addition (4) a detailed non-invasive analysis of both endogenous and exogenous gene expression in animal models and in the clinical setting. Non-invasive imaging of endogenous gene expression by means of positron emission tomography (PET) may reveal insight into the molecular basis of pathogenesis and metabolic activity of the glioma and the extent of treatment response. When exogenous genes are introduced to serve for a therapeutic function, PET imaging techniques may reveal the assessment of the location, magnitude and duration of therapeutic gene expression and its relation to the therapeutic effect. Here, we review the main principles of PET imaging and its key roles in neurooncology research.

Diagnosis and staging of Rasmussen's encephalitis by serial MRI and histopathology

OBJECTIVE

To correlate MRI and histopathologic findings in patients with Rasmussen's encephalitis (RE).

PATIENTS AND METHODS

MRI features of 10 patients with RE were studied on serial scans. In surgical specimens from these patients, densities of T lymphocytes, microglial cells and nodules, and reactive astrocytes were evaluated.

RESULTS

Densities of T cells, microglial nodules, and astrocytes were inversely correlated to disease duration. MRI abnormalities had a focal onset and spread across one hemisphere. The following course of MRI abnormalities in a given brain region was observed: on very early scans, the cortex was swollen and showed a hyperintense T2/fluid-attenuated inversion recovery signal. Consecutively, progressive atrophy of the affected hemisphere occurred. Correlation of MRI features with quantitative histopathology revealed that there was a higher number of T cells and reactive astrocytes in the earlier MRI stages compared with the late (merely atrophic) stage.

CONCLUSION

These data suggest a disease course in RE with the highest inflammatory intensity in the early stages and a subsequent decrease in inflammation. The MRI abnormalities and their characteristic sequence may help to identify patients with RE and to obtain informative biopsies.

Toxoplasma gondii infection of neurons induces neuronal cytokine and chemokine production, but gamma interferon- and tumor necrosis factor-stimulated neurons fail to inhibit the invasion and growth of T. gondii

The intracellular parasite Toxoplasma gondii has the capacity to persist in the brain within neurons. In this study we demonstrated that T. gondii infected murine cerebellar neurons in vitro and replicated within these cells. Stimulation with gamma interferon (IFN-gamma) and/or tumor necrosis factor (TNF) did not enable neurons to inhibit parasite invasion and replication. Cultured neurons constitutively produced interleukin 1 (IL-1), IL-6, macrophage inflammatory protein 1alpha (MIP-1alpha), and MIP-1beta but not transforming growth factor beta1 (TGF-beta1), IL-10, and granulocyte-macrophage colony-stimulating factor. Neuronal expression of some cytokines (IL-6, TGF-beta1) and chemokines (MIP-1beta) was regulated by infection and/or by IFN-gamma and TNF.

Human herpes virus-8 is not associated with primary central nervous system lymphoma in HIV-negative patients

Primary central nervous system lymphomas (PCNSL) are derived from germinal center B cells. Recent molecular studies indicate that the tumor cells or their precursors have experienced antigenic stimulation. Attractive candidates for such antigens are pathogens with the capacity to reside in the brain. The aim of the present study was to evaluate whether human herpes virus (HHV)-8 is involved in the pathogenesis of PCNSL. A series of 46 PCNSL, 31 from HIV-negative and 15 from HIV-positive patients, were analyzed using various molecular biological and immunological approaches. Nested PCR with two different protocols unequivocally demonstrated that PCNSL from HIV-negative patients did not harbor HHV-8 DNA. Among AIDS-associated PCNSL, HHV-8 DNA was found in only 1 tumor. In situ hybridization studies revealed that the lymphoma cells were HHV-8 negative in all cases. Single small mononuclear cells, most likely corresponding to bystander lymphocytes, were identified as the cellular source of HHV-8 in the HIV-positive patient with an HHV-8 PCR signal. These studies largely rule out a role for HHV-8 in the pathogenesis of PCNSL in both HIV-negative as well as HIV-positive patients.

Combined systemic and intraventricular chemotherapy in primary CNS lymphoma: a pilot study

The objective was to evaluate response rate, response duration, and toxicity after systemic and intraventricular chemotherapy in primary CNS lymphoma (PCNSL). From September 1995 to September 1998, 20 consecutive patients with PCNSL (median age 64, range 27 to 71 years) were enrolled in a pilot study evaluating chemotherapy without radiotherapy. A high dose methotrexate (MTX) (cycles 1, 2, 4, 5) and cytarabine (ara-C) (cycles 3, 6) based systemic therapy (including dexamethasone, vinca alkaloids, ifosfamide, and cyclophosphamide) was combined with intraventricular MTX, prednisolone, and ara-C. Complete response was achieved in 11 and partial remission in two patients; in one response could not be determined. Four patients showed progressive disease and two (70, 71 years) died from treatment related complications. Observation time was 2 to 59 months (median 31.5 months). Kaplan-Meier estimate for median time to treatment failure (TTF) was 20.5 months, and for median survival 54 months. Systemic toxicity was mainly hematological. Ommaya reservoir infection occurred in four patients and acute transient MTX induced encephalopathy in two (subacute in another). Cognitive dysfunction possibly due to treatment was seen in only one patient after relapse and after a total of 12 cycles (six at relapse). In conclusion, primary chemotherapy based on high dose MTX and ara-C is highly efficient in PCNSL. Toxicity is manageable in patients younger than 70 years.

Endogenous interleukin-10 is required for prevention of a hyperinflammatory intracerebral immune response in Listeria monocytogenes meningoencephalitis

To analyze the role of interleukin-10 (IL-10) in bacterial cerebral infections, we studied cerebral listeriosis in IL-10-deficient (IL-10(-/-)) and wild-type (WT) mice, the latter of which express high levels of IL-10 in both primary and secondary cerebral listeriosis. IL-10(-/-) mice succumbed to primary as well as secondary listeriosis, whereas WT mice were significantly protected from secondary listeriosis by prior intraperitoneal immunization with Listeria monocytogenes. Meningoencephalitis developed in both strains; however, in IL-10(-/-) mice the inflammation was more severe and associated with increased brain edema and multiple intracerebral hemorrhages. IL-10(-/-) mice recruited significantly increased numbers of leukocytes, in particular granulocytes, to the brain, and the intracerebral cytokine (tumor necrosis factor, IL-1, IL-12, gamma interferon, and inducible nitric oxide synthase) and chemokine (crg2/IP-10, RANTES, MuMig, macrophage inflammatory protein 1alpha [MIP-1alpha], and MIP-1beta) transcription was enhanced compared to that in WT mice. Despite this prominent hyperinflammation, the frequencies of intracerebral L. monocytogenes-specific CD8(+) T cells were reduced and the intracerebral bacterial load was not reduced in IL-10(-/-) mice compared to WT mice. Following intraperitoneal infection, IL-10(-/-) mice exhibited hepatic hyperinflammation without better bacterial clearance; however, in contrast to the mice with cerebral listeriosis, they did not succumb, illustrating that intrinsic factors of the target organ have a strong impact on the course and outcome of the infection.

Vav2 activates c-fos serum response element and CD69 expression but negatively regulates nuclear factor of activated T cells and interleukin-2 gene activation in T lymphocyte

Vav1 and Vav2 are members of the Dbl family of guanine nucleotide exchange factors for the Rho family of small GTPases. Although the role of Vav1 during lymphocyte development and activation is well characterized, the function of Vav2 is still unclear. In this study, we compared the signaling pathways regulated by Vav1 and Vav2 following engagement of the T cell receptor (TCR). We show that Vav2 is tyrosine-phosphorylated upon TCR stimulation and by co-expressed Src and Syk family kinases. Using glutathione S-transferase fusion proteins, we observed that the Src homology 2 domain of Vav2 binds tyrosine-phosphorylated proteins from TCR-stimulated Jurkat T cell lysates, including c-Cbl and SLP-76. Like Vav1, Vav2 cooperated with TCR stimulation to increase extracellular signal-regulated kinase activation and to promote c-fos serum response element transcriptional activity. Moreover, both proteins displayed a similar action in increasing the expression of the early activation marker CD69 in Jurkat T cells. However, in contrast to Vav1, Vav2 dramatically suppressed TCR signals leading to nuclear factor of activated T cells (NF-AT)-dependent transcription and induction of the interleukin-2 promoter. Vav2 appears to act upstream of the phosphatase calcineurin because a constitutively active form of calcineurin rescued the effect of Vav2 by restoring TCR-induced NF-AT activation. Interestingly, the Dbl homology and Src homology 2 domains of Vav2 were necessary for its inhibitory effect on NF-AT activation and for induction of serum response element transcriptional activity. Taken together, our results indicate that Vav1 and Vav2 exert overlapping but nonidentical functions in T cells. The negative regulatory pathway elicited by Vav2 might play an important role in regulating lymphocyte activation processes.

New developments in the pathology of skull base tumors

As an anatomical interface between various tissues, the skull base harbors an exceptionally broad variety of neoplasms, some of which pose a major challenge for surgical pathology. The characterization of distinct immunohistochemical expression profiles and the identification of molecular genetic alterations associated with different tumor entities have significantly advanced this field. The new World Health Organization (WHO) classification of tumors of the nervous system lists 15 histopathological variants of meningioma. Of clinical importance are those entities that carry an increased risk of recurrence and a poor prognosis, i.e., the atypical meningioma (WHO grade II), clear-cell meningioma (WHO grade II), chordoid meningioma (WHO grade II), rhabdoid meningioma (WHO grade III), papillary meningioma (WHO grade III), and anaplastic meningioma (WHO grade III). Diagnostic criteria for atypical and anaplastic meningioma variants have now been stringently defined. The differential diagnosis of meningiomas includes hemangiopericytoma, hemangioblastoma, solitary fibrous tumor, sarcomas, and chordoid neoplasms. Recent data highlight the importance of distinguishing chordoma and chondrosarcoma of the skull base since chondrosarcomas show a significantly better clinical outcome. Among the less common, aggressive tumor entities in this anatomical region, infiltrating pituitary adenoma/pituitary carcinoma, superficial malignant gliomas, rhabdomyosarcoma, olfactory neuroblastoma, various sarcomas, and malignant lymphoma must be considered. Profiles of molecular genetic alterations have been established for several of these neoplasms and may facilitate the differential diagnosis. This review summarizes recent developments in the histopathological characterization, classification, and molecular pathology of neoplasms arising at the skull base.

Vav-Rac1-mediated activation of the c-Jun N-terminal kinase/c-Jun/AP-1 pathway plays a major role in stimulation of the distal NFAT site in the interleukin-2 gene promoter

Vav, a hematopoiesis-specific signaling protein, plays an important role in T-cell development and activation. Vav upregulates the expression of the interleukin-2 (IL-2) gene, primarily via activation of the distal NFAT site in the IL-2 gene promoter (NFAT-IL-2). However, since this site cooperatively binds NFAT and AP-1, the relative contribution of Vav to NFAT versus AP-1 activation has not been determined. Here, we studied the respective roles of the AP-1 and NFAT pathways in the T-cell receptor (TCR)-mediated, Vav-dependent activation of NFAT-IL-2. Although Vav stimulated the transcriptional activity of an NFAT-IL-2 reporter gene, it failed to stimulate the transcriptional or DNA-binding activities of an AP-1-independent NFAT site derived from the human gamma interferon gene promoter. Vav also did not stimulate detectable Ca(2+) mobilization and nuclear translocation of NFATc or NFATp. On the other hand, Vav induced the activation of Rac1 or Cdc42 and c-Jun N-terminal kinase (JNK), enhanced the transcriptional and DNA-binding activities of AP-1, and induced increased phosphorylation of c-Jun. Dominant-negative Vav and/or Rac1 mutants blocked the TCR-mediated stimulation of these events, demonstrating the physiological relevance of these effects. Vav also associated with Rac1 or Cdc42 in T cells, and anti-CD3 antibody stimulation enhanced this association. These findings indicate that a Rac1-dependent JNK/c-Jun/AP-1 pathway, rather than the Ca(2+)/NFAT pathway, plays the predominant role in NFAT-IL-2 activation by Vav.

Differential requirements for ERK1/2 and P38 MAPK activation by thrombin in T cells. Role of P59Fyn and PKCε

Activation of the mitogen-activated protein kinase (MAPK) cascade is a well documented mechanism for the G-protein-coupled receptors. Here, we have analysed the requirements for ERKs and p38 MAPK activation by thrombin in Jurkat T cells. We show that thrombin-mediated ERKs activation requires both PTK and PKC activities, whereas p38 MAPK activation is dependent only on PTKs. Thrombin-induced ERK and p38 MAPK activation was more pronounced in p56Lck deficient cells indicating that this PTK exerts a negative control on MAPK activity. Accordingly, overexpression of p50 Csk a kinase that inactivates p56Lck induced constitutive activation of ERKs. Requirement for a Src kinase was evidenced by expression of a constitutively active form of p59Fyn in Jurkat cells. Besides its effect on tyrosine phosphorylation events, thrombin also triggered a rapid and robust redistribution of PKCepsilon and delta from the cytosol to the membrane. Expression of constitutively active and dominant negative PKCepsilon demonstrates the pivotal role of this PKC isoform in ERKs activation by thrombin. These data are consistent with a model where thrombin induces ERK activation via both PKC-dependent and independent pathways, whereas p38 MAPK activation requires only PTKs. The PKC-independent pathway requires Src kinases other than p56Lck more likely p59Fyn, while the PKC-dependent mechanism depends on PKCepsilon

Limbic encephalitis not associated with neoplasm as a cause of temporal lobe epilepsy

OBJECTIVE

To describe four patients with temporal lobe epilepsy with limbic encephalitis unrelated to neoplasm.

METHODS

The authors performed a retrospective evaluation of patient data obtained during presurgical evaluation, with additional CSF analyses, serum analyses, and histopathologic investigations.

RESULTS

The patients shared the following clinical features: onset of the disease in young adulthood with subacute onset or exacerbation of frequent intractable temporal lobe seizures, verbal and visual memory deficits, and affective abnormalities. MRI showed variably extended areas of increased T2 signal in limbic structures and adjacent areas. In the histopathologic investigation, chronic inflammation was observed without evidence of a viral origin. There was no evidence of an underlying malignancy.

CONCLUSIONS

Nonparaneoplastic limbic encephalitis should be included in the differential diagnosis of adult patients with temporal lobe epilepsy.

Primary CNS lymphoma: clinical presentation, pathological classification, molecular pathogenesis and treatment

Primary CNS lymphomas (PCNSL) represent malignant non-Hodgkin's B cell lymphomas, which are confined to the central nervous system. They show a dramatic increase in frequency in the immunocompromised as well as in the immunocompetent population. Recent studies have identified germinal center B cells as the cellular origin of PCNSL; however, the details of their molecular pathogenesis still remain to be elucidated. Treatment recommendations are not clearly established. Radiotherapy (RT) is efficient in terms of tumor response, but not curative. Median survival after RT alone is about 1 year. According to the results of uncontrolled studies the combination of RT and chemotherapy based on high-dose methotrexate (HD-MTX) is most efficient in terms of survival rates. However, long-term neurotoxicity overshadows treatment efficacy, especially in patients over 60 years of age. The authors favor the systematic evaluation of chemotherapy alone with protocols including HD MTX, because unicenter results are promising in terms of both survival as well as quality of life in long term survivors.

Glomerular permselectivity in early stages of overt diabetic nephropathy

BACKGROUND

Impairment of glomerular size selectivity has been demonstrated by the dextran-sieving technique in nephropathic diabetics with heavy, but not mild proteinuria. The purpose of the present study was to determine whether such a barrier defect could be demonstrated with mild proteinuria by substituting Ficoll 70, a polysucrose, for dextran as a probe of the filtration barrier.

METHODS

Differential solute clearances were performed in 12 individuals with early diabetic nephropathy on two occasions: after 60 days of treatment with losartan 50 mg daily or a placebo. An uncharged preparation of nonreabsorbable Ficoll 70 was infused along with inulin. Fractional clearance (theta) of Ficoll of discrete size was determined after separating molecules in urine and plasma in narrow 2 A fractions over a 20 to 60 A radius interval by size exclusion high-performance liquid chromatography (HPLC). A hydrodynamic theory of hindered ficoll transport through water-filled pores was used to characterize the pore size distribution of the glomerular barrier.

RESULTS

The theta for Ficoll molecules with radii> 50 A was selectively enhanced in placebo-treated diabetic nephropathy versus corresponding theta in healthy control subjects (N = 12). Computations revealed a lower distribution of glomerular pores that was unaltered in nephropathic diabetics. However, an upper distribution of large, shunt-like pores was more prominent, exceeding healthy controls by one order of magnitude in diabetic nephropathy (P = 0.01). A trend to lower theta for Ficoll in the 56 to 60 A radius range during losartan therapy is computed to have lowered the fraction of shunted filtrate by 26 to 44%, depending on whether glomerular pressure declined. The corresponding reduction in theta for endogenous albumin, IgG, and IgG4 was by 19 to 23% (P < 0.05).

CONCLUSION

Our findings suggest that shunt-like defects, partially reversible by angiotensin II blockade, are present early in the course of diabetic nephropathy. We estimate that such defects can account for immunoglobulinuria in this disorder. Additional impairment of either charge- or shape-selectivity must be invoked to explain the observed level of albuminuria, however.

Glycosylphosphatidylinositol (GPI)-deficient Jurkat T cells as a model to study functions of GPI-anchored proteins

Many cell surface proteins attached to the membrane by GPI are involved in cell signalling. However, the role of the GPI membrane anchor itself remains poorly understood. GPI-defective cells from patients with paroxysmal nocturnal haemoglobinuria (PNH) are relatively resistant to apoptosis induction. We developed a Jurkat T cell model for GPI deficiency by isolating a GPI-negative mutant, which is defective in the GPI biosynthetic gene PIG-A. Using retroviral PIG-A gene transfer along with the transfer of a vector control, we obtained two genetically identical cell lines, distinguished only by expression of the PIG-A gene and, thus, their ability to produce GPI. Cell proliferation and survival were not affected by this difference. Apoptotic stimuli such as serum starvation and camptothecin exposure elicited similar responses. In contrast, GPI-defective Jurkat cells were more susceptible to Fas-mediated apoptosis than GPI-positive cells. These results indicate that a deficiency in GPI-anchored proteins, as is found in PNH, does not confer resistance to apoptosis.

The divergent role of tumor necrosis factor receptors in infectious diseases

Tumor necrosis factor (TNF) receptor types 1 and 2 are broadly expressed by most cell types and are activated by binding of either TNF or lymphotoxin-beta. TNF receptor-mediated immune reactions are critically important in the pathogenesis and control of a variety of infections caused by bacteria, viruses, protozoa, and fungi. This review summarizes recent findings on the role of TNF receptors in infectious diseases and discusses the divergent functions of these receptors in immune responses.