Search for histamine H3 receptor antagonists with combined inhibitory potency at Ntau-methyltransferase: ether derivatives.

With the recent development of new hybrid compounds having histamine H3 receptor antagonist with combined histamine Ntau-methyltransferase (HMT) inhibitory potency an innovative approach was described in the research of novel lead compounds modulating histaminergic neurotransmission. Several compounds containing an ether moiety derived from the recently published 4-(3-piperidinopropoxy)phenylaminoquinoline derivatives (like FUB 836), were synthesized in this study and tested for their affinity at cloned human histamine H3 (hH3) receptors and on the inhibition of rat HMT. Besides different heterocycles, e.g. nitro- or amino-substituted pyridines, quinolines, benzothiazole or pyrroline, three classes of compounds were produced: heteroaromatic 3-piperidinopropyl ethers, keto- or imino-substituted 4-(3-piperidinopropyl)phenyl ethers and 4-(3-piperidinopropyl)phenyl ethers with substituted (alkyl)aminopyridines. Whereas the (3-piperidinopropoxy)heterocycles showed only moderate activities on both test models, the 4-(3-piperidinopropoxy)phenyl derivatives were identified as potent histamine H3 receptor ligands and/or HMT inhibitors. Ki values up to 0.42 nM were found for the affinity to the hH3 receptor. HMT inhibitory potency was identified with IC50 values about 0.3 microM for the most potent compounds in this series. Comparison of the pyridine-containing derivatives to recently published quinoline analogues showed a decrease in potencies for the pyridines. The dual activity, H3 receptor affinity and HMT inhibition, was moderate to good. For all compounds affinities at hH3 receptors were higher than their inhibitory HMT potencies. The described new histamine H3 receptor antagonists with an ether moiety represent a further promising step in our investigations for a dual activity.

Constrained testing conditions affect the axial rotation response of lumbar functional spinal units.

STUDY DESIGN: Human cadaveric spine specimens were tested in axial rotation using constrained and unconstrained methods. OBJECTIVES: To determine the degree to which constrained methods affect the response of the functional spinal unit in axial rotation at lumbar and lumbosacral levels. SUMMARY OF BACKGROUND DATA: A substantial controversy exists in the literature regarding the appropriateness of different testing methods. No study has been found in which the effect of constraint on axial rotation behavior was objectively examined. METHODS: Ten human cadaveric spine specimens (five L3-L4, five L5-S1) were tested in axial rotation, using both constrained and unconstrained methods. In the unconstrained test, pure moments were applied to the upper vertebra, and its complete three-dimensional motion was measured using an optoelectronic camera system. In the constrained test, the specimens were loaded in a fixed-axis servohydraulic test machine individually around five rotational axis positions within the vertebral body, and the rotational motion was measured. RESULTS: The rotational angles in the constrained tests were not different among the five rotational axis positions. However, the maximum rotation from the five axis positions was approximately 40% greater than the minimum rotation, a significant difference. The axial rotational motion of the unconstrained tests was always less than the maximum rotation measured in the constrained test. However, the total rotational angle using the helical axis of motion was not significantly different from the constrained angles. CONCLUSIONS: The large differences between maximum and minimum rotation angles demonstrate that the behavior of the functional spinal unit in axial rotation is sensitive to the axis's position but the location of the axis is not repeatable. This supports the use of unconstrained methods in spinal testing.

Influence of imidazole replacement in different structural classes of histamine H(3)-receptor antagonists.

The reference compounds for histamine H(3)-receptor antagonists carry as a common feature an imidazole moiety substituted in the 4-position. Very recently novel ligands lacking an imidazole ring have been described possessing a N-containing non-aromatic heterocycle instead. In this study we investigated whether imidazole replacement, favourably by a piperidine moiety, is generally applicable to different structural classes of reference compounds, e.g., thioperamide, carboperamide, clobenpropit, FUB 181, ciproxifan, etc. While replacement led to a loss of affinity for many of the compounds, it was successfully applied to some ether derivatives. The piperidine analogues of FUB 181 and ciproxifan, 3-(4-chlorophenyl)propyl 3-piperidinopropyl ether hydrogen oxalate (6) and cyclopropyl 4-(3-piperidinopropyloxy)phenyl methanone hydrogen maleate (7), almost maintained in vitro affinities, pK(i) values of 7.8 and 8.4, respectively, and showed high potency in vivo after p.o. administration (ED(50) values of 1.6 and 0.18 mg/kg, respectively).

Interbody cage stabilisation in the lumbar spine: biomechanical evaluation of cage design, posterior instrumentation and bone density.

We performed a biomechanical study on human cadaver spines to determine the effect of three different interbody cage designs, with and without posterior instrumentation, on the three-dimensional flexibility of the spine. Six lumbar functional spinal units for each cage type were subjected to multidirectional flexibility testing in four different configurations: intact, with interbody cages from a posterior approach, with additional posterior instrumentation, and with cross-bracing. The tests involved the application of flexion and extension, bilateral axial rotation and bilateral lateral bending pure moments. The relative movements between the vertebrae were recorded by an optoelectronic camera system. We found no significant difference in the stabilising potential of the three cage designs. The cages used alone significantly decreased the intervertebral movement in flexion and lateral bending, but no stabilisation was achieved in either extension or axial rotation. For all types of cage, the greatest stabilisation in flexion and extension and lateral bending was achieved by the addition of posterior transpedicular instrumentation. The addition of cross-bracing to the posterior instrumentation had a stabilising effect on axial rotation. The bone density of the adjacent vertebral bodies was a significant factor for stabilisation in flexion and extension and in lateral bending.

RIG-I-like helicases induce immunogenic cell death of pancreatic cancer cells and sensitize tumors toward killing by CD8(+) T cells.

Pancreatic cancer is characterized by a microenvironment suppressing immune responses. RIG-I-like helicases (RLH) are immunoreceptors for viral RNA that induce an antiviral response program via the production of type I interferons (IFN) and apoptosis in susceptible cells. We recently identified RLH as therapeutic targets of pancreatic cancer for counteracting immunosuppressive mechanisms and apoptosis induction. Here, we investigated immunogenic consequences of RLH-induced tumor cell death. Treatment of murine pancreatic cancer cell lines with RLH ligands induced production of type I IFN and proinflammatory cytokines. In addition, tumor cells died via intrinsic apoptosis and displayed features of immunogenic cell death, such as release of HMGB1 and translocation of calreticulin to the outer cell membrane. RLH-activated tumor cells led to activation of dendritic cells (DCs), which was mediated by tumor-derived type I IFN, whereas TLR, RAGE or inflammasome signaling was dispensable. Importantly, CD8α(+) DCs effectively engulfed apoptotic tumor material and cross-presented tumor-associated antigen to naive CD8(+) T cells. In comparison, tumor cell death mediated by oxaliplatin, staurosporine or mechanical disruption failed to induce DC activation and antigen presentation. Tumor cells treated with sublethal doses of RLH ligands upregulated Fas and MHC-I expression and were effectively sensitized towards Fas-mediated apoptosis and cytotoxic T lymphocyte (CTL)-mediated lysis. Vaccination of mice with RLH-activated tumor cells induced protective antitumor immunity in vivo. In addition, MDA5-based immunotherapy led to effective tumor control of established pancreatic tumors. In summary, RLH ligands induce a highly immunogenic form of tumor cell death linking innate and adaptive immunity.

The role of supplemental translaminar screws in anterior lumbar interbody fixation: a biomechanical study.

The immediate stabilization provided by anterior interbody cage fixation is often questioned. Therefore, the role of supplementary posterior fixation, particularly minimally invasive techniques such as translaminar screws, is relevant. The purpose of this biomechanical study was to determine the immediate three-dimensional flexibility of the lumbar spine, using six human cadaveric functional spinal units, in four different conditions: (1) intact, (2) fixed with translaminar screws (TLS), (3) instrumented with anterior interbody cage insertion with the BAK system and (4) instrumented with BAK cage with additional TLS fixation. Flexibility was determined in each testing condition by measuring the vertebral motions under applied pure moments (i.e. flexion-extension, bilateral axial rotation, bilateral lateral bending) in an unconstrained manner. Anterior fixation with the BAK alone provided significant stability in flexion and lateral bending. Additional posterior TLS significantly reduced the motion in extension and axial rotation. TLS fixation alone resulted in smaller rotations than BAK fixation in all loading directions. Based on these results, it seems that interbody cage fixation with the BAK system stabilizes the spine in some, but not all, loading directions. The problematic loading directions of extension and axial rotation can be substantially stabilized by using translaminar screw fixation. However, one should emphasize that the degree of stability needed to achieve solid fusion is not known.