Dedicated locking plate reduces non-union risk in open ankle fusion in obese patients.

INTRODUCTION: Obesity is a growing public health concern. In ankle osteoarthritis, non-conservative treatment in advanced stages consists in ankle fusion, or else total ankle replacement, for which obesity is a relative contraindication. One of main complications of ankle fusion is non-union. Devascularization, obesity and fixation material are all factors involved in postoperative non-union, and have to be taken into account in surgical strategy for reliable results. The objective of this study was to compare the rate of ankle non-union in obese patients using quadruple screwing or a dedicated locking plate. The hypothesis was that the locking plate limits the risk of non-union in this population. METHODS: All patients were obese (BMI>30kg/m2) and presented ankle osteoarthritis with>10° intra-articular deformity. The approach and joint preparation were performed via an anteromedial approach. Group S was composed of 32 patients, operated on by quadruple screwing; group P comprised 10 patients operated on using a dedicated locking plate. The main endpoint was a significant difference in the rate of non-union between the 2 groups. The secondary endpoint was improvement in pre- and 6-month postoperative AOFAS score. RESULTS: Group S presented 31% non-union (10/32) and group P 0% (0/10) (p<0.05). Postoperative AOFAS score was significantly higher in group P: 67.8±10.4 [range, 40-92] vs. 83.1±8.0 [range, 64-92] (p<0.05). CONCLUSION: The dedicated anterior locking plate is a technique of choice for ankle fusion in obese patients with intra-articular deformity>10°, to limit the risk of non-union. LEVEL OF EVIDENCE: IV; retrospective study.

Spontaneous breathing trial with pressure support on positive end-expiratory pressure and extensive use of non-invasive ventilation versus T-piece in difficult-to-wean patients from mechanical ventilation: a randomized controlled trial.

BACKGROUND: The aim of this study is to assess whether a strategy combining spontaneous breathing trial (SBT) with both pressure support (PS) and positive end-expiratory pressure (PEEP) and extended use of post-extubation non-invasive ventilation (NIV) (extensively-assisted weaning) would shorten the time until successful extubation as compared with SBT with T-piece (TP) and post-extubation NIV performed in selected patients as advocated by guidelines (standard weaning), in difficult-to-wean patients from mechanical ventilation. METHODS: The study is a single-center prospective open label, randomized controlled superiority trial with two parallel groups and balanced randomization with a 1:1 ratio. Eligible patients were intubated patients mechanically ventilated for more than 24 h who failed their first SBT using TP. In the extensively-assisted weaning group, SBT was performed with PS (7 cmH2O) and PEEP (5 cmH2O). In case of SBT success, an additional SBT with TP was performed. Failure of this SBT-TP was an additional criterion for post-extubation NIV in this group in addition to other recommended criteria. In the standard weaning group, SBT was performed with TP, and NIV was performed according to international guidelines. The primary outcome criterion was the time between inclusion and successful extubation evaluated with a Cox model with adjustment on randomization strata. RESULTS: From May 2019 to March 2023, 98 patients were included and randomized in the study (49 in each group). Four patients were excluded from the intention-to-treat population (2 in both groups); therefore, 47 patients were analyzed in each group. The extensively-assisted weaning group had a higher median age (68 [58-73] vs. 62 [55-71] yrs.) and similar sex ratio (62% male vs. 57%). Time until successful extubation was not significantly different between extensively-assisted and standard weaning groups (median, 172 [50-436] vs. 95 [47-232] hours, Cox hazard ratio for successful extubation, 0.88 [95% confidence interval: 0.55-1.42] using the standard weaning group as a reference; p = 0.60). All secondary outcomes were not significantly different between groups. CONCLUSION: An extensively-assisted weaning strategy did not lead to a shorter time to successful extubation than a standard weaning strategy. Trial registration The trial was registered on ClinicalTrials.gov (NCT03861117), on March 1, 2019, before the inclusion of the first patient. https://clinicaltrials.gov/study/NCT03861117 .

The "Metaizeau trick" to facilitate medullary pubic ramus screw insertion: A technical note.

Minimally invasive procedures have recently seen an increase in the treatment of pelvic ring disruptions and select acetabular fractures. Similar to ilio-sacral screws, the superior pubic ramus screw is becoming a preferred method for treating unstable pelvic ring fractures. While the osteology of the superior pubic ramus is well understood and has inherent variability, standard screw insertion techniques work effectively in most cases. If the anatomy prevents the standard approach, there are alternative methods that can be employed for successful screw placement, or there might be a need for an open reduction and internal fixation with plates. Such techniques can be material-intensive and time-consuming. In this paper, we introduce a straightforward method that utilizes the Metaizeau nail as a guide wire to facilitate screw insertion in most instances, termed the "Metaizeau trick". Metaizeau nails, commonly found in trauma centers, are designed to locate a pathway effortlessly using this method. LEVEL OF EVIDENCE: IV.

Laparoscopic treatment of fourteen cases of pelvic ring disruption: a case series.

PURPOSE: Open surgical approaches for the treatment of anterior pelvic arc lesions are associated with several complications. We present the first retrospective descriptive case series on the use of laparoscopy as an alternative. METHODS: This descriptive, retrospective, single-centre study enrolled all patients who underwent laparoscopy for the treatment of pelvic ring disruption between May 2020 and March 2022. The primary outcome was the procedure failure rate based on conversion to open surgery. Secondary outcomes were the duration of the surgical procedure, x-ray exposure, length of hospitalisation, postoperative pain assessment, and functional scores at the last follow-up. RESULTS: The study included two females and 12 males. The mean age of the study participants was 44.2 (23-67) years. In total, nine (64.3%) patients had pubic symphysis disjunction, four (28.6%) had bilateral fractures of the obturator frames, and one (7%) had both. None of the patients required conversion to open surgery. The median operating times for symphysis pubis disruption, obturator frame fracture, and patients with both injuries were 90.0 (60-120), 135 (105-180), and 240 min, respectively. The median overall operating time was 102.5 (60-240) min. The median Iowa Pelvic Score and Majeed Functional Score at the last follow-up were 87 (70-99) and 84 (70-100), respectively. CONCLUSION: Laparoscopic internal fixation is a reliable treatment for pelvic ring disruption. The clinical and radiological outcomes of our patients suggest the usefulness of this technique as an alternative to open approaches.

Management of acute grade IV and greater acromioclavicular dislocations: Open acromioclavicular brace versus arthroscopic double DogBone® endobutton.

INTRODUCTION: Several surgical techniques exist to manage grade IV acute acromioclavicular dislocation (ACD). However, the conventional acromioclavicular brace technique (ACB) has never been compared to the arthroscopic DogBone® (DB) double endobutton technique. The aim of this work was to compare the functional and radiological results of DB stabilization with those of ACB. HYPOTHESIS: DB stabilization provides similar functional results with a low rate of radiological recurrences compared to ACB. MATERIAL AND METHODS: This is a case-control study comparing 17 cases of ACD operated by DB (DB group) between January 2016 and January 2021 with 31 cases of ACD operated by ACB (ACB group) between January 2008 and January 2016. The primary outcome was the difference in the D/A ratio (reflecting vertical displacement) measured on an anteroposterior acromioclavicular (AC) X-ray compared between the 2 groups at one-year after surgery. The secondary outcome was a clinical evaluation at one-year using the Constant score and clinical AC instability. RESULTS: At revision, the mean D/A ratio in the DB and ACB groups was 0.4±0.5 [-0.4-1.6] and 1.6±0.3 [0.8-3.1] respectively (p>0.05). Two patients (11.7%) in the DB group had implant migration with radiological recurrence while 14 patients (33%) had radiological recurrence in the ACB group (p<0.05). CONCLUSION: The DB technique limits the radiographic recurrence of acute ACD with an equivalent functional result at 1-year postoperatively compared to the conventional ACB technique, which implicitly requires a second operation for hardware removal. The DB technique has become the technique of choice in first-line treatment of acute grade IV ACD. LEVEL OF EVIDENCE: III; retrospective case-control series.

Corona mortis and pelvic dissection: Understanding the relationship between anatomical structures and bone areas.

Pelvic fractures are becoming increasingly frequent. The gold standard for surgical managements remains open procedures. Despite its excellent biomechanically results, it can lead to many complications. Minimally invasive surgery could reduce these complications. For complex pelvic trauma, extraperitoneal endoscopic technique has never been described. The aim of this study is to determine anatomical landmarks which are useful for endoscopic pelvic ring surgery using an extraperitoneal approach. The second objective is to compare this minimally invasive procedure to expose the bone versus a traditional open approach. After preparing the vessels with latex injections, 10 specimens are dissected alternately, using an endoscopic method (MIS) on one side and an open method on the other side. Both procedures are performed on the same subject. The visualized bone areas are drilled with burr holes. The marked surfaces are measured with photogrammetry. Finally, the data are processed (surface analysis). An extraperitoneal endoscopic dissection that follows anatomical landmarks can be performed. Bone area (mm2 ) visualized by endoscopy was 74 ± 14 (59-94) compared to 71 ± 16 (48-94) by open method. Paired t-test was performed with no significant difference between the two methods. Skin and muscular incisions were significantly lower in the MIS group (5.1, IC95% [4.1; 6.1], p < 0.001). An extraperitoneal endoscopic dissection of the pelvis can be performed. We also find no significant difference between our method and an open traditional approach concerning bone exposure. We offer a holistic approach to treat pelvic fractures by identifying key anatomical structures.

C-Nail® locking nail versus conventional plate for thalamic calcaneal fractures.

BACKGROUND: Surgery for displaced intra-articular calcaneal fractures (DIACFs) is often followed by skin complications that adversely impacts the functional outcomes. Minimally invasive techniques have been developed to decrease the risk of skin complications. The objective of this study was to compare C-Nail® locking-nail fixation to conventional plate fixation for DIACFs. HYPOTHESIS: C-Nail® fixation restores calcaneal anatomy similarly to conventional plate fixation and decreases the frequency of skin complications compared to conventional plate fixation, while providing satisfactory functional outcomes. MATERIAL AND METHODS: In this case-control study of DIACFs, fixation was with a non-locking plate in 30 patients treated between January 2016 and June 2017 and with the C-Nail® in 25 patients treated between April 2017 and April 2018. Computed tomography was performed before surgery then bilaterally after surgery for measurements of the following calcaneal parameters: height, length, width, joint-surface step-off and inter-fragmentary distance. The values of these parameters were compared between the two groups. Postoperative skin complications were recorded. The functional outcome was assessed by determining the AOFAS score 1 year after the injury. RESULTS: The two groups showed no significant differences for age, sex or fracture type. Wound healing was delayed in 3 patients in the plate group. The mean postoperative values of the calcaneal parameters were not significantly different between the two groups. The mean AOFAS score was 85.3±10.4 (range, 50-100) in the plate group and 87.0±12.0 (range, 64-100) in the C-Nail® group (p>0.05). DISCUSSION: Minimally invasive C-Nail® fixation provides similar restoration of calcaneal anatomy as does conventional plate fixation. LEVEL OF EVIDENCE: III, retrospective case-control study.

On the difficulties of characterizing weak protein interactions that are critical for neurotransmitter release.

The mechanism of neurotransmitter release has been extensively characterized, showing that vesicle fusion is mediated by the SNARE complex formed by syntaxin-1, SNAP-25 and synaptobrevin. This complex is disassembled by N-ethylmaleimide sensitive factor (NSF) and SNAPs to recycle the SNAREs, whereas Munc18-1 and Munc13s organize SNARE complex assembly in an NSF-SNAP-resistant manner. Synaptotagmin-1 acts as the Ca2+ sensor that triggers exocytosis in a tight interplay with the SNAREs and complexins. Here, we review technical aspects associated with investigation of protein interactions underlying these steps, which is hindered because the release machinery is assembled between two membranes and is highly dynamic. Moreover, weak interactions, which are difficult to characterize, play key roles in neurotransmitter release, for instance by lowering energy barriers that need to be overcome in this highly regulated process. We illustrate the crucial role that structural biology has played in uncovering mechanisms underlying neurotransmitter release, but also discuss the importance of considering the limitations of the techniques used, including lessons learned from research in our lab and others. In particular, we emphasize: (a) the promiscuity of some protein sequences, including membrane-binding regions that can mediate irrelevant interactions with proteins in the absence of their native targets; (b) the need to ensure that weak interactions observed in crystal structures are biologically relevant; and (c) the limitations of isothermal titration calorimetry to analyze weak interactions. Finally, we stress that even studies that required re-interpretation often helped to move the field forward by improving our understanding of the system and providing testable hypotheses.

Prevalence and risk factors of hemodynamic instability associated with preload-dependence during continuous renal replacement therapy in a prospective observational cohort of critically ill patients.

BACKGROUND: Hemodynamic instability is a frequent complication of continuous renal replacement therapy (CRRT). Postural tests (i.e., passive leg raising in the supine position or Trendelenburg maneuver in the prone position) combined with measurement of cardiac output are highly reliable to identify preload-dependence and may provide new insights into the mechanisms involved in hemodynamic instability related to CRRT (HIRRT). We aimed to assess the prevalence and risk factors of HIRRT associated with preload-dependence in ICU patients. We conducted a single-center prospective observational cohort study in ICU patients with acute kidney injury KDIGO 3, started on CRRT in the last 24 h, and monitored with a PiCCO® device. The primary endpoint was the rate of HIRRT episodes associated with preload-dependence during the first 7 days after inclusion. HIRRT was defined as the occurrence of a mean arterial pressure below 65 mmHg requiring therapeutic intervention. Preload-dependence was assessed by postural tests every 4 h, and during each HIRRT episode. Data are expressed in median [1st quartile-3rd quartile], unless stated otherwise. RESULTS: 42 patients (62% male, age 69 [59-77] year, SAPS-2 65 [49-76]) were included 6 [1-16] h after CRRT initiation and studied continuously for 121 [60-147] h. A median of 5 [3-8] HIRRT episodes occurred per patient, for a pooled total of 243 episodes. 131 episodes (54% [CI95% 48-60%]) were associated with preload-dependence, 108 (44%, [CI95% 38-51%]) without preload-dependence, and 4 were unclassified. Multivariate analysis (using variables collected prior to HIRRT) identified the following variables as risk factors for the occurrence of HIRRT associated with preload-dependence: preload-dependence before HIRRT [odds ratio (OR) = 3.82, p < 0.001], delay since last HIRRT episode > 8 h (OR = 0.56, p < 0.05), lactate (OR = 1.21 per 1-mmol L-1 increase, p < 0.05), cardiac index (OR = 0.47 per 1-L min-1 m-2 increase, p < 0.001) and SOFA at ICU admission (OR = 0.91 per 1-point increase, p < 0.001). None of the CRRT settings was identified as risk factor for HIRRT. CONCLUSIONS: In this single-center study, HIRRT associated with preload-dependence was slightly more frequent than HIRRT without preload-dependence in ICU patients undergoing CRRT. Testing for preload-dependence could help avoiding unnecessary decrease of fluid removal in preload-independent HIRRT during CRRT.

Prone Positioning in Spontaneously Breathing Subjects With Moderate or Severe ARDS During Invasive Ventilation.

BACKGROUND: Prone positioning (PP) during invasive mechanical ventilation improves outcomes of patients with severe ARDS. Recent studies suggest that PP in spontaneously breathing, nonintubated patients with acute respiratory failure is well tolerated and improves oxygenation. However, little is known regarding patient triggered ventilation in intubated patients with ARDS undergoing PP. We conducted a retrospective review of our experience with placing patients in the prone position in 2 cohorts of subjects with moderate and severe ARDS (ie, one cohort with ARDS related to COVID-19, the other with ARDS unrelated to COVID-19), many of whom were receiving pressure support ventilation (PSV). METHODS: We conducted a retrospective analysis in a single 22-bed mixed ICU. The subjects included in the analysis were ≥ 18 y old, met the Berlin definition for moderate or severe ARDS (whether related COVID-19 or not), and underwent PP during invasive ventilation. RESULTS: 39 subjects were included in the analysis: 20 subjects had ARDS related to COVID-19, while 19 had ARDS related to other etiologies. A total of 113 PP episodes were analyzed: 84 during PSV and 29 during volume control continuous mandatory ventilation. PP during PSV was well tolerated and was effective in improving arterial oxygenation (ie, an increase of median [Formula: see text] from 100 mm Hg [interquartile range 75-120] before PP to 135 mm Hg [interquartile range 111-161] at the end of the PP session, P < .0001). No significant difference between continuous mandatory ventilation and PSV was noted regarding arterial oxygenation during PP. Compared with continuous mandatory ventilation mode, PP during PSV was associated with a significant decrease in the use of neuromuscular blocking agents (4% vs 69% of subjects, P < .001), while sedative requirements remained unchanged. CONCLUSIONS: In a retrospective analysis of consecutive intubated subjects with moderate or severe ARDS, related or not to COVID-19, spontaneous breathing during PP was well tolerated and achieved significant improvement in arterial oxygenation.

Phosphorylation of the Hepatitis B Virus Large Envelope Protein.

We here establish the phosphorylation sites in the human hepatitis B virus (HBV) large envelope protein (L). L is involved in several functionally important interactions in the viral life cycle, including with the HBV cellular receptor, HBV capsid, Hsc70 chaperone, and cellular membranes during fusion. We have recently shown that cell-free synthesis of the homologous L protein of duck HBV in wheat germ extract results in very similar phosphorylation events to those previously observed in animal cells. Here, we used mass spectrometry and NMR to establish the phosphorylation patterns of human HBV L protein produced by both in vitro cell-free synthesis and in E. coli with the co-expression of the human MAPK14 kinase. While in the avian virus the phosphorylation of L has been shown to be dispensable for infectivity, the identified locations in the human virus protein, both in the PreS1 and PreS2 domains, raise the intriguing possibility that they might play a functional role, since they are found at strategic sites predicted to be involved in L interactions. This would warrant the further investigation of a possible function in virion formation or cell entry.

Quantitative-analysis of computed tomography in COVID-19 and non COVID-19 ARDS patients: A case-control study.

PURPOSE: The aim of this study was to assess whether the computed tomography (CT) features of COVID-19 (COVID+) ARDS differ from those of non-COVID-19 (COVID-) ARDS patients. MATERIALS AND METHODS: The study is a single-center prospective observational study performed on adults with ARDS onset ≤72 h and a PaO2/FiO2 ≤ 200 mmHg. CT scans were acquired at PEEP set using a PEEP-FiO2 table with VT adjusted to 6 ml/kg predicted body weight. RESULTS: 22 patients were included, of whom 13 presented with COVID-19 ARDS. Lung weight was significantly higher in COVID- patients, but all COVID+ patients presented supranormal lung weight values. Noninflated lung tissue was significantly higher in COVID- patients (36 ± 14% vs. 26 ± 15% of total lung weight at end-expiration, p < 0.01). Tidal recruitment was significantly higher in COVID- patients (20 ± 12 vs. 9 ± 11% of VT, p < 0.05). Lung density histograms of 5 COVID+ patients with high elastance (type H) were similar to those of COVID- patients, while those of the 8 COVID+ patients with normal elastance (type L) displayed higher aerated lung fraction.

Modelling the effect of temperature on the biology and demographic parameters of the African coffee white stem borer, Monochamus leuconotus (Pascoe) (Coleoptera: Cerambycidae).

The African coffee white stem borer Monochamus leuconotus (Pascoe) (Coleoptera: Cerambycidae) is a destructive insect pest of Arabica coffee trees in African highlands. Our study aims to provide information on the pest biology as influenced by temperature, determine thermal thresholds, and provide life table parameters for M. leuconotus reared in the laboratory. The life cycle of M. leuconotus was studied at seven constant temperatures in the range 15-35 °C, with 80 ± 5% RH and a photoperiod of L:D 12:12. Linear and nonlinear models were fitted to laboratory data to describe the impact of temperature on M. leuconotus development, mortality, fecundity and senescence. The complete life cycle was obtained between 18 and 30 °C, with the egg incubation period ranging 10.8-29.2 days. The development time was longest for the larva, with 194.2 days at 30 °C and 543.1 days at 18 °C. The minimum temperature threshold (Tmin) was estimated at 10.7, 10.0 and 11.5 °C, for egg, larva and pupa, respectively. The maximum temperature threshold (Tmax) was estimated at 37.4, 40.6 and 40.0 °C for egg, larva and pupa, respectively. The optimum temperature for immature stage survival was estimated between 23.0 and 23.9 °C. The highest fecundity was 97.8 eggs per female at 23 °C. Simulated life table parameters showed the highest net reproductive rate (Ro) of 11.8 daughters per female at 26 °C and maximal intrinsic rate of increase (rm) between 26 and 28 °C, with a value of 0.008. Our results will help understanding M. leuconotus biology as influenced by temperature and may be used to predict the distribution and infestation risk under climate warming for this critical coffee pest.

Phosphorylation and Alternative Translation on Wheat Germ Cell-Free Protein Synthesis of the DHBV Large Envelope Protein.

Wheat-germ cell-free protein synthesis (WG-CFPS) is a potent platform for the high-yield production of proteins. It is especially of interest for difficult-to-express eukaryotic proteins, such as toxic and transmembrane proteins, and presents an important tool in high-throughput protein screening. Until recently, an assumed drawback of WG-CFPS was a reduced capacity for post-translational modifications. Meanwhile, phosphorylation has been observed in WG-CFPS; yet, authenticity of the respective phosphorylation sites remained unclear. Here we show that a viral membrane protein, the duck hepatitis B virus (DHBV) large envelope protein (DHBs L), produced by WG-CFPS, is phosphorylated upon translation at the same sites as DHBs L produced during DHBV infection of primary hepatocytes. Furthermore, we show that alternative translation initiation of the L protein, previously identified in virus-producing hepatic cells, occurs on WG-CFPS as well. Together, these findings further strengthen the high potential of WG-CFPS to include the reproduction of specific modifications proteins experience in vivo.

Structural Studies of Self-Assembled Subviral Particles: Combining Cell-Free Expression with 110†kHz MAS NMR Spectroscopy.

Viral membrane proteins are prime targets in combatting infection. Still, the determination of their structure remains a challenge, both with respect to sample preparation and the need for structural methods allowing for analysis in a native-like lipid environment. Cell-free protein synthesis and solid-state NMR spectroscopy are promising approaches in this context, the former with respect to its great potential in the native expression of complex proteins, and the latter for the analysis of membrane proteins in lipids. Herein, we show that milligram amounts of the small envelope protein of the duck hepatitis B virus (DHBV) can be produced by cell-free expression, and that the protein self-assembles into subviral particles. Proton-detected 2D NMR spectra recorded at a magic-angle-spinning frequency of 110 kHz on <500 µg protein show a number of isolated peaks with line widths comparable to those of model membrane proteins, paving the way for structural studies of this protein that is homologous to a potential drug target in HBV infection.

Time domain compressive beam forming of ultrasound signals.

Ultrasound imaging is a wide spread technique used in medical imaging as well as in non-destructive testing. The technique offers many advantages such as real-time imaging, good resolution, prompt acquisition, ease of use, and low cost compared to other techniques such as x-ray imaging. However, the maximum frame rate achievable is limited as several beams must be emitted to compute a single image. For each emitted beam, one must wait for the wave to propagate back and forth, thus imposing a limit to the frame rate. Several attempts have been made to use less beams while maintaining image quality. Although efficiently increasing the frame rate, these techniques still use several transmit beams. Compressive Sensing (CS), a universal data completion scheme based on convex optimization, has been successfully applied to a number of imaging modalities over the past few years. Using a priori knowledge of the signal, it can compute an image using less data allowing for shorter acquisition times. In this paper, it is shown that a valid CS framework can be derived from ultrasound propagation theory, and that this framework can be used to compute images of scatterers using only one plane wave as a transmit beam.

Strong antibacterial properties of anion transporters: a result of depolarization and weakening of the bacterial membrane.

The development of low molecular weight anionophores is an emerging topic in chemistry, as the need for these compounds increases with the continuous discovery of pathologies involving anomalies in anion transport processes. Development of new concepts to initiate anion imbalance in living cells while fighting multidrug-resistant bacteria is a paramount topic. In this study, three series of compounds including N,N'-diphenylethynylbenzyl benzimidazolium salts (1 and 2), 1,1'-(pyridine-2,6-diyl)bis(3-(4-(phenylethynyl)benzyl)-1H-benzo[d]imidazol-3-ium) salts (3-5), and 1,1'-(pyridine-2,6-diylbis(methylene))bis(3-(4-(phenyl ethynyl)benzyl)-1H-benzo[d]imidazol-3-ium) salts (6-8) displaying high antimicrobial activity and low toxicity against human cells were designed, synthesized, and studied. The most potent compound displayed micromolar minimal inhibitory concentrations in different Gram-negative and Gram-positive bacteria, while its hemolytic activity remained around 10% or less, even after a prolonged period of exposure. The mechanism of action of these benzimidazolium salts on bacterial membrane was assessed by bioanalytical techniques including assays in model membrane liposomes, membrane depolarization studies, and scanning electron microscopy (SEM) in living bacteria.

In vivo three-dimensional photoacoustic imaging based on a clinical matrix array ultrasound probe.

We present an integrated photoacoustic and ultrasonic three-dimensional (3-D) volumetric imaging system based on a two-dimensional (2-D) matrix array ultrasound probe. A wavelength-tunable dye laser pumped by a Q-switched Nd:YAG laser serves as the light source and a modified commercial ultrasound imaging system (iU22, Philips Healthcare) with a 2-D array transducer (X7-2, Philips Healthcare) detects both the pulse-echo ultrasound and photoacoustic signals. A multichannel data acquisition system acquires the RF channel data. The imaging system enables rendering of co-registered 3-D ultrasound and photoacoustic images without mechanical scanning. The resolution along the azimuth, elevation, and axial direction are measured to be 0.69, 0.90 and 0.84 mm for photoacoustic imaging. In vivo 3-D photoacoustic mapping of the sentinel lymph node was demonstrated in a rat model using methylene blue dye. These results highlight the clinical potential of 3-D PA imaging for identification of sentinel lymph nodes for cancer staging in humans.