Apoptosis (programmed cell death) plays a key role in the pathogenesis of many disorders including cerebral and myocardial ischemia, autoimmune and neurodegenerative diseases, infections, organ and bone marrow transplant rejection, and tumor response to chemotherapy and/or radiotherapy. Apoptosis in itself represents a complex mechanism where numerous (pro-apoptotic and anti-apoptotic) molecules interact in an elaborate manner. Since the original description by Kerr et al. in 1972, clinical assessment of apoptosis has always required biopsies or aspirated material for in vitro investigations. Several well-established methods are available for in vitro tests using tissue specimens. However, a non-invasive detection of apoptosis would be of great benefit for many patients in various situations. Today, non-invasive techniques for direct in vivo detection of apoptotic cells are rare and urgently need improvement. The early in vivo detection of apoptotic cells can provide the physician with important information to develop further therapeutic strategies in chemotherapy or radiotherapy of tumors, in transplantation of organs, or in healing of infarct areas. In some preliminary publications, several authors reported on the in vivo use of caspase-inhibitors and annexin V, labeled with indium-111, technetium-99m, iodine-123, iodine-124 or fluoride-18. In the present paper, we review the current applicability of both techniques for in vivo apoptosis imaging, and discuss the methodical problems.

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The p53 and bcl-2 expression profiles and the observed apoptotic rates of FTC-133 and ML-1 under irradiation are consistent with a more aggressive FTC-133 phenotype. Alterations in p53- and bcl-2 protein levels yield predictive information for EBRT efficacy.

The previously described HIV-1 directed hammerhead ribozyme 2as-Rz12 can form with its target RNA 2s helices I and III of 128 and 278 base pairs (bp). A series of derivatives was made in which helix III was truncated to 8, 5, 4, 3, and 2 nucleotides (nt). These asymmetric hammerhead ribozymes were tested for in vitro cleavage and for inhibition of HIV-1 replication in human cells. Truncation of helix III to 8 bp did not affect the in vitro cleavage potential of the parental catalytic antisense RNA 2as-Rz12. Further truncation of helix III led to decreased cleavage rates, with no measurable cleavage activity for the 2 bp construct. All catalytically active constructs showed complex cleavage kinetics. Three kinetic subpopulations of ribozyme-substrate complexes could be discriminated that were cleaved with fast or slow rates or not at all. Gel purification of preformed ribozyme-substrate complexes led to a significant increase in cleavage rates. However, the complex cleavage pattern remained. In mammalian cells, the helix III-truncated constructs showed the same but no increased inhibitory effect of the comparable antisense RNA on HIV-1 replication.

Brain and leptomeningeal metastasis (LMM) of non-small cell lung cancer is still associated with poor prognosis. Moreover, the current diagnostic standard for LMM often yields false negative results and the scientific progress in this field is still unsatisfying.We present a case of a 71-year old patient with an isolated LMM. While standard diagnostics could only diagnose a cancer of unknown primary, the use of [68Ga]-Pentixafor-PET/CT (CXCR4-PET/CT, a radiotracer targeting CXCR4) and a liquid biopsy of the cerebrospinal fluid revealed the primary NSCLC. The detection of L858R-EGFR, a common driver mutation in NSCLC, enabled us to treat the patient with Afatinib and monitor treatment using [68Ga]-Pentixafor PET/CT. To estimate the impact of CXCR4 signaling and its ligands in NSCLC brain metastasis we looked at their expression and correlation with EGFR mutations in a primary and brain metastasis data set and investigated the previously described binding of extracellular ubiquitin to CXCR4.In conclusion, we describe a novel approach to improve diagnostics towards LMM and underline the impact of the CXCL12/CXCR4 axis in brain metastasis in a subset of NSCLC patients. We cannot confirm a correlation of CXCR4 expression with EGFR mutations or the binding of extracellular ubiquitin as previously reported.