Water-film thickness imaging based on time-multiplexed near-infrared absorption with up to 500 Hz repetition rate

We demonstrate high-repetition-rate imaging of the liquid-film thickness in the 50-1000 µm range resulting from impinging water droplets on a glass surface. The pixel-by-pixel ratio of line-of-sight absorption at two time-multiplexed near-infrared wavelengths at 1440 and 1353 nm was detected with a high-frame-rate InGaAs focal-plane array camera. Frame rates of 1 kHz and thus measurement rates of 500 Hz could be achieved, well suited to capture the fast dynamics of droplet impingement and film formation. The droplets were sprayed onto the glass surface using an atomizer. Suitable absorption wavelength bands for water droplet/film imaging were determined from Fourier-transform infrared (FTIR) spectra of pure water between 298 and 338 K. At 1440 nm, the water absorption is nearly temperature-independent, making the measurements robust against temperature fluctuations. Time-resolved imaging measurements capturing the dynamics of the water droplet impingement and evolution were successfully demonstrated.

Simultaneous measurement of liquid-film thickness and solute concentration of aqueous solutions of two urea derivatives using NIR absorption

We present a method to simultaneously measure the film thickness and individual concentrations of two urea derivates (urea CH₄N₂O and dimethylurea C₃H₈N₂O) mixed in an aqueous solution at constant temperature using near-infrared (NIR) absorption at multiple specific wavelengths. Fourier transform infrared (FTIR) spectra of aqueous mixtures of urea and dimethylurea solutions were recorded in the 1250-2500 nm wavelength range in thin-layer quartz cuvettes at room temperature. The spectra reveal suitable detection wavelengths, i.e., 1450, 1933, 2200, and 2270 nm, for which both the absorption coefficient and its variation with the species concentration are large enough to achieve satisfactory detection sensitivity and selectivity. For validation measurements, samples were prepared in thin-layer quartz transmission cells with known path lengths and mixture compositions in the range 100-1000 µm and 0-40 wt.%, respectively. Film thickness and mass fractions of both species were determined from measured absorbance ratios in the determined characteristic wavelength bands.

The Relation Between Long-Term Synaptic Plasticity at Glutamatergic Synapses in the Amygdala and Fear Learning in Adult Heterozygous BDNF-Knockout Mice

Brain-derived neurotrophic factor (BDNF) heterozygous knockout mice (BDNF+/- mice) show fear learning deficits from 3 months of age onwards. Here, we addressed the question how this learning deficit correlates with altered long-term potentiation (LTP) in the cortical synaptic input to the lateral amygdala (LA) and at downstream intra-amygdala synapses in BDNF+/- mice. Our results reveal that the fear learning deficit in BDNF+/- mice was not paralleled by a loss of LTP, neither at cortical inputs to the LA nor at downstream intra-amygdala glutamatergic synapses. As we did observe early fear memory (30 min after training) in BDNF+/- mice while long-term memory (24 h post-training) was absent, the stable LTP in cortico-LA and downstream synapses is in line with the intact acquisition of fear memories. Ex vivo recordings in acute slices of fear-conditioned wildtype (WT) mice revealed that fear learning induces long-lasting changes at cortico-LA synapses that occluded generation of LTP 4 and 24 h after training. Overall, our data show that the intact LTP in the tested amygdala circuits is consistent with intact acquisition of fear memories in both WT and BDNF+/- mice. In addition, the lack of learning-induced long-term changes at cortico-LA synapses in BDNF+/- mice parallels the observed deficit in fear memory consolidation.

Presynaptic Regulation of Tonic Inhibition by Neuromodulatory Transmitters in the Basal Amygdala

Tonic inhibition mediated by ambient levels of GABA that activate extrasynaptic GABA_A receptors emerges as an essential factor that tunes neuronal network excitability in vitro and shapes behavioral responses in vivo. To address the role of neuromodulatory transmitter systems on this type of inhibition, we employed patch clamp recordings in mouse amygdala slice preparations. Our results show that the current amplitude of tonic inhibition (I_tonic) in projection neurons of the basal amygdala (BA) is increased by preincubation with the neurosteroid THDOC, while the benzodiazepine diazepam is ineffective. This suggests involvement of THDOC sensitive δ subunit containing GABA_A receptors in mediating tonic inhibition. Moreover, we provide evidence that the neuromodulatory transmitters NE, 5HT, and ACh strongly enhance spontaneous IPSCs as well as I_tonic in the BA. As the increase in frequency, amplitude, and charge of sIPSCs by these neuromodulatory transmitters strongly correlated with the amplitude of I_tonic, we conclude that spill-over of synaptic GABA leads to activation of I_tonic and thereby to dampening of amygdala excitability. Since local injection of THDOC, as a positive modulator of tonic inhibition, into the BA interfered with the expression of contextual fear memory, our results point to a prominent role of I_tonic in fear learning.

Clinical and Molecular Phenotypes of Low-Penetrance Variants of NLRP3: Diagnostic and Therapeutic Challenges

OBJECTIVE

Cryopyrin-associated periodic syndromes (CAPS) result from gain-of-function mutations in the NLRP3 gene, which causes excessive release of interleukin-1β (IL-1β) and systemic inflammation. While pathogenetic NLRP3 variant phenotypes are well-characterized, low-penetrance NLRP3 variants represent a significant clinical challenge. The aims of this study were to determine the clinical phenotype, the in vitro biologic phenotype, and the effect of anti-IL-1 treatment in patients with low-penetrance NLRP3 variants.

METHODS

A multicenter study of consecutive symptomatic patients with low-penetrance NLRP3 variants recruited from 7 centers between May 2012 and May 2013 was performed. The observed findings were transferred into a study database, from which they were extracted for analysis. Controls were patients with a known pathogenetic NLRP3 variant. Clinical presentation and CAPS markers of inflammation were captured. Functional assays of inflammasome activation, including caspase 1 activity, NF-κB release, cell death, and IL-1β release, were performed. Treatment effects of IL-1 were determined. Comparisons between low-penetrance and pathogenetic NLRP3 variants were performed.

RESULTS

The study included 45 patients, 21 of which were female (47%); 26 of the patients (58%) were children. NLRP3 low-penetrance variants identified in the patients were Q703K (n = 19), R488K (n = 6), and V198M (n = 20). In the controls, 28 had pathogenetic NLRP3 variants. Patients with low-penetrance NLRP3 variants had significantly more fever (76%) and gastrointestinal symptoms (73%); eye disease, hearing loss, and renal involvement were less common. Functional inflammasome testing identified an intermediate phenotype in low-penetrance NLRP3 variants as compared to wild-type and pathogenetic NLRP3 variants. All treated patients responded to IL-1 inhibition, with complete response documented in 50% of patients.

CONCLUSION

Patients with low-penetrance NLRP3 variants display a distinct clinical phenotype and an intermediate biologic phenotype, including IL-1β and non-IL-1β-mediated inflammatory pathway activation.

Postsynaptic BDNF signalling regulates long-term potentiation at thalamo-amygdala afferents

The neurotrophin brain-derived neurotrophic factor (BDNF) is known to regulate synaptic plasticity and memory formation in the hippocampus and the neocortex of the mammalian brain. In contrast, a role of BDNF in mediating synaptic plasticity and fear learning in the amygdala is just beginning to evolve. Using patch clamp recordings from projection neurons of the dorsal lateral amygdala (LA) in acute slices of mice, we now investigated the cellular mechanism of BDNF-mediated long-term potentiation (LTP) of excitatory postsynaptic currents (EPSCs) in the amygdala. LTP was elicited in cortical and thalamic synaptic inputs by pairing postsynaptic depolarisation with presynaptic stimulation. LTP in the cortico-amygdala pathway was not changed in heterozygous BDNF-knockout (BDNF(+/-)) mice. In contrast, pairing induced LTP in the thalamic input was abolished in BDNF(+/-) mice (BDNF(+/-): 104.0 ± 5.7% of initial EPSC values; WT: 132.5 ± 7.3%). Likewise, inhibition of BDNF/TrkB signalling with TrkB-IgGs as scavenger molecules for endogenous BDNF blocked LTP in wild-type mice in this pathway (TrkB-IgG: 102.7 ± 6.9% of initial EPSC values; control: 132.5 ± 8.7%). Inclusion of the tyrosine kinase inhibitor K252a in the pipette solution also prevented the induction of LTP in the thalamic pathway, indicating a postsynaptic site of action of BDNF in regulating LTP. Reduced BDNF levels in BDNF(+/-) mice did not affect intrinsic membrane properties of LA projection neurons. Likewise, presynaptic glutamate release, and postsynaptic membrane properties also remained unaffected in BDNF(+/-) mice. These data suggest a postsynaptic site of action of BDNF in mediating LTP selectively in the thalamic fear conditioning pathway.

Reorientierende Arthrodese des oberen Sprunggelenks in der 4-Schrauben-Technik

BACKGROUND

Arthrodesis of the ankle has gained wide acceptance as a first-line treatment option for painful posttraumatic osteoarthritis. The technique using four to five lag screws for internal osteosynthesis is a safe and biomechanically stable method to obtain a sound ankle fusion with good to excellent long-term results in the majority of patients. Malalignment hazards are minimized by preservation of the ankle mortise.

METHODS

The meticulous resection of all cartilage and sclerotic bone as well as an atraumatic surgical technique are essential for preventing major complications. The need for revision surgery is minimized by correction of talar malalignment, fusion with the foot in a 90 degrees position and preoperative evaluation of the subtalar joint. In a series of 40 ankle fusions fixed with the lag screw technique, 82.5% good to excellent results were obtained after 5.6 (4.8-7.6) years. No infection, stress fracture or non-union was seen.

RESULTS

In cases of osteitis, osteonecrosis, osteoporosis, and poor soft-tissue condition, external fixation techniques are preferred. In the presence of severe loss of bone stock at the distal tibia, stability can be achieved by using a compression nail for tibiotalar fusion without additional subtalar arthrodesis.

Vorteile der minimal-invasiven Reposition, Retention und Ilizarov-(Hybrid)Fixation bei Pilon-tibiale-Frakturen unter besonderer Ber�cksichtigung von C2-/C3-Frakturen

Between October 1993 and September 1999 a total of 62 tibial pilon fractures in 59 patients were treated at the Clinic for Trauma and Reconstructive Surgery, University Hospital Carl-Gustav-Carus, Technical University Dresden. In a retrospective study 49 patients with 50 tibial pilon fractures (81%) could be examined an average of 28 months after injury. The purpose of this study was to compare clinically and radiographically the healing results obtained after using the Ilizarov technique in combination with minimally invasive internal fixation (group I) with those after a conventional surgical procedure (internal fixation with a plate, external fixation with or without minimally invasive internal fixation, and screw fixation exclusively, group II) and to evaluate the efficacy of the Ilizarov technique. Data analysis showed a significantly higher incidence of 43 C2/C3 fractures in Ilizarov group I (73%) than in group II (33.3%). Severe soft tissue injuries and particularly open injuries had a significantly higher incidence in Ilizarov group I (100%) than in group II (38%). Despite the high incidence of C2/C3 fractures and severe soft tissue injuries in group I, there was no incidence of pseudarthrosis or osteitis in the further course and there was no need for arthrodesis during the long-term course. After therapy with a conventional surgical technique, the incidence of osteitis was 5% and of delayed union of a fracture 2.5% and arthrodesis was necessary in 8%. A disadvantage of the Ilizarov system was the relatively frequent incidence of pin infection (45%) necessitating surgical debridement in 18%. The efficacy of the treatment of 43 C2/C3 fractures with the Ilizarov technique was obvious by a statistically significantly better Maryland Foot Score in comparison with group II. More than 87% of the patients treated with the Ilizarov technique and only 38% of the patients treated with a conventional surgical procedure obtained a very good or good score. According to these findings, the Ilizarov technique in combination with minimally invasive internal fixation is an effective method to treat complicated tibial pilon fractures with severe soft tissue trauma.

[Clinical evaluation of the distal femoral nail]

METHOD

The clinical results after DFN-osteosynthesis of n=56 AO-classification 33A-fractures (32%), 33C-fractures (43%), 32X-fractures (21%) and pseudarthrosis treatment (4%) are presented.

RESULTS

Follow up was available for 54 fractures (96%) after a mean of 1.2 years (range 0.2-2.8 years). 95% of patients showed full-weight-bearing with a knee flexion of 120 (60-140) degrees. Extension-deficit >10 degrees was observed in 5.4%. All fractures were consolidated. One soft-tissue infection, one partial loss of reduction and one implant failure were observed. A significant axial malalignment was found radiologically in 17%, a loosened spiralblade or locking screw in 7.4%. In 91% of cases the result was judged as good to excellent by patients and surgeons.

CONCLUSION

The mechanical stability of the implant allows a save osteosynthesis of unstable supracondylar and complete articular femoral fractures without additional bone grafting. Mechanical stability and minimal invasive operative technique permit a safe bone healing without major complications.

[Clinical trial with the distal femoral nail]

METHODS

The clinical results after DFN-osteosynthesis of n = 56 AO-classification 33A-fractures (32%), 33C-fractures (43%), 32X-fractures (21%) and treatment of non-union (4%) are presented.

RESULTS

Follow-up was available for 54 fractures (96%) after a mean of 1.2 years (range 0.2-2.8 years). 95% of patients showed full-weight-bearing with a knee flexion of 120 (60-140) degrees. Extension-deficit > 10 degrees was observed in 5.4%. All fractures were consolidated. One soft-tissue infection, one partial loss of reduction and one implant failure were observed. A significant axial malalignment was found radiologically in 17%, a loosened spiralblade or locking screw in 7.4%. In 91% of cases the result was judged as good to excellent by patients.

CONCLUSION

The mechanical stability of the implant allows a save osteosynthesis of unstable supracondylar and complete articular femoral fractures without additional bone grafting. Mechanical stability and minimal invasive operative technique permit a safe bone healing without major complications.