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Objective To identify the outcome of patients with sepsis using high-frequency blood pressure data. Materials and methods This retrospective observational study was conducted at a university hospital ICU (derivation study) and at two urban hospitals (validation study) with data from adult sepsis patients who visited the centers during the same period. The area under the curve (AUC) of blood pressure falling below threshold was calculated. The predictive 90-day mortality (primary endpoint) area under threshold (AUT) and critical blood pressure were calculated as the maximum area under the curve of the receiver operating characteristic curve (AUCROC) and the threshold minus average AUT (derivation study), respectively. For the validation study, the derived 90-day mortality AUCROC (using critical blood pressure) was compared with Sequential Organ Failure Assessment (SOFA), Simplified Acute Physiology Score (SAPS) II, Acute Physiology and Chronic Health Evaluation (APACHE) II, and APACHE III. Results Derivation cohort (N = 137): the drop area from the mean blood pressure of 70 mmHg at 24-48 hours most accurately predicted 90-day mortality [critical blood pressure, 67.8 mmHg; AUCROC, 0.763; 95% confidence interval (CI), 0.653-0.890]. Validation cohort (N = 141): the 90-day mortality AUCROC (0.776) compared with the AUCROC for SOFA (0.711), SAPSII (0.771), APACHE II (0.745), and APACHE III (0.710) was not significantly different from the critical blood pressure 67.8 mmHg (P = 0.420). Conclusion High-frequency arterial blood pressure data of the period and extent of blood pressure depression can be useful in predicting the clinical outcomes of patients with sepsis.

Intelligent image-activated cell sorting (iIACS) is a machine-intelligence technology that performs real-time intelligent image-based sorting of single cells with high throughput. iIACS extends beyond the capabilities of fluorescence-activated cell sorting (FACS) from fluorescence intensity profiles of cells to multidimensional images, thereby enabling high-content sorting of cells or cell clusters with unique spatial chemical and morphological traits. Therefore, iIACS serves as an integral part of holistic single-cell analysis by enabling direct links between population-level analysis (flow cytometry), cell-level analysis (microscopy), and gene-level analysis (sequencing). Specifically, iIACS is based on a seamless integration of high-throughput cell microscopy (e.g., multicolor fluorescence imaging, bright-field imaging), cell focusing, cell sorting, and deep learning on a hybrid software-hardware data management infrastructure, enabling real-time automated operation for data acquisition, data processing, intelligent decision making, and actuation. Here, we provide a practical guide to iIACS that describes how to design, build, characterize, and use an iIACS machine. The guide includes the consideration of several important design parameters, such as throughput, sensitivity, dynamic range, image quality, sort purity, and sort yield; the development and integration of optical, microfluidic, electrical, computational, and mechanical components; and the characterization and practical usage of the integrated system. Assuming that all components are readily available, a team of several researchers experienced in optics, electronics, digital signal processing, microfluidics, mechatronics, and flow cytometry can complete this protocol in ~3 months.

Background While hand and ultrasonic scalers are the primary tools used for the removal of dental calculus in periodontal treatment, many studies have shown that they also damage the enamel surface. We have developed a novel actuator-driven pulsed water jet (ADPJ) system, which has the ability to selectively remove materials depending on their stiffness. Considering the different material properties between teeth and dental calculus, it might be possible to develop the ADPJ to remove dental calculus without damage to the tooth’s enamel surface using a suitable jet pressure. Therefore, the aim of this study was to assess the effectiveness of the ADPJ in removing dental calculus, and the surface features of the teeth after its use. Methods A total of 93 artificial teeth coated with artificial dental calculus were examined in this study. The weights of 90 teeth were measured before and after the use of ADPJ, which had an applied voltage setting of 150, 200, or 240 V. The three remaining teeth were instrumented with a conventional hand scaler, ultrasonic scaler, or ADPJ (set at 240 V). Damage to the artificial tooth surfaces was evaluated using 5% Evans blue dye under an optical microscope. Furthermore, apatite pellets, which are utilized as experimental substitutes for natural teeth, were assessed after the use of ADPJ and both conventional scalers. Results The ADPJ significantly reduced the amount of artificial calculus, and the removal rate was dependent on the applied voltage. No damage was observed on the surface of the artificial tooth and apatite pellet following the use of ADPJ, in contrast to the conventional scalers. Conclusions The results of this study demonstrate the in vitro effectiveness of ADPJ in the removal of dental calculus, without causing damage to tooth surfaces.

The advent of intelligent image-activated cell sorting (iIACS) has enabled high-throughput intelligent image-based sorting of single live cells from heterogeneous populations. iIACS is an on-chip microfluidic technology that builds on a seamless integration of a high-throughput fluorescence microscope, cell focuser, cell sorter, and deep neural network on a hybrid software-hardware data management architecture, thereby providing the combined merits of optical microscopy, fluorescence-activated cell sorting (FACS), and deep learning. Here we report an iIACS machine that far surpasses the state-of-the-art iIACS machine in system performance in order to expand the range of applications and discoveries enabled by the technology. Specifically, it provides a high throughput of ∼2000 events per second and a high sensitivity of ∼50 molecules of equivalent soluble fluorophores (MESFs), both of which are 20 times superior to those achieved in previous reports. This is made possible by employing (i) an image-sensor-based optomechanical flow imaging method known as virtual-freezing fluorescence imaging and (ii) a real-time intelligent image processor on an 8-PC server equipped with 8 multi-core CPUs and GPUs for intelligent decision-making, in order to significantly boost the imaging performance and computational power of the iIACS machine. We characterize the iIACS machine with fluorescent particles and various cell types and show that the performance of the iIACS machine is close to its achievable design specification. Equipped with the improved capabilities, this new generation of the iIACS technology holds promise for diverse applications in immunology, microbiology, stem cell biology, cancer biology, pathology, and synthetic biology.

Background Pulsed water jet dissection is an emerging surgical method for achieving maximal resection of a lesion and postoperative function preservation. We aimed to clarify liver damage and long-term results after liver resection using a novel surgical device, piezo actuator-driven pulsed water jet (ADPJ), in a rat model.Methods We categorizedSprague–Dawley rats into four groups and subjected themto sham operation or liver resection using an ADPJ, an ultrasonic aspirator (UA), or a radio knife. At 1, 3, 7, 14, 28, and 56 days postoperatively, we euthanizedfive rats from each group after collecting blood samples and harvested residual livers.We measured serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and glutamate dehydrogenase (GLDH) concentrations. Morphological characteristics and resection surfaces were assessed by hematoxylin–eosin staining.ResultsOn day 1, serum AST and ALT levels were significantly lower with an ADPJ than with an UA and a radio knife (AST: ADPJ vs. UA, PPPPPPPPConclusionsLiver damage afterliver resection was markedly less with an ADPJ than with an UA or a radio knife. Furthermore, the liver recovered faster after an ADPJ.

There is limited information about acute phase renal replacement therapy (RRT) for maintenance hemodialysis patients after the onset of cerebrovascular disease. This study aimed to investigate which modality of renal replacement therapy is currently selected in practice. We conducted a mail-based survey in 317 dialysis facilities that were certified by three academic societies that focus on dialysis, neurology, and neurosurgery in Japan. We received responses from 103 facilities (32.5%). In cases of cerebral infarction (CI) and intracerebral hemorrhage (ICH), more than 80% of the facilities selected only intermittent RRT, and 22.3% (CI)/8.7% (ICH) of the facilities selected intermittent HD which is the same setting in normal conditions. Although continuous hemodiafiltration and peritoneal dialysis are recommended in the Japanese guidelines, these were selected in only a few facilities: 16.5% and 0% in CI, 16.5% and 1% in ICH, respectively. RRT on the day of onset tended to be avoided, irrespective of the duration following the last HD session. Furthermore, physicians preferred to modify anticoagulants and reduce dialysis performance in the acute phase. This questionnaire survey uncovered a gap between guidelines and actual practice, even in hospitals accredited as educational facility, which is a novel and important finding. Further studies with larger sample sizes are needed to determine the optimal modality of RRT for the acute phase of cerebrovascular disease.

Objective Maximum resection with minimum damage to normal structures is required for a better clinical outcome. Several efficient surgical devices such as the Cavitron ultrasonic surgical aspirator are available. Our group developed the actuator-driven pulsed water jet (ADPJ) to dissect soft tissue with vessel preservation. Although these devices are very effective for resection, tumor seeding is a potential risk. The present study investigated the control of splashing during ADPJ use. We demonstrate the effect of additional water flow around the instrument tip to veil the splashing. Methods Pulsed water jet was ejected from the tip of the ADPJ nozzle. Effects of ADPJ parameters such as input voltage, suction pressure, and distance between the nozzle and the target (standoff distance) on the amount of splashing were analyzed. Methylene blue solution was ejected on photo paper, gelatin brain phantom, and porcine brain harvested and subsequently immersed into physiologic saline to quantify the amount of splashing. Results High-input voltage and a long standoff distance had significant correlations with large amounts of splashing (r > 0.5; p Conclusions The veil effect of additional water flow is important to reduce splashing during ADPJ use and can minimize the potential risk of dissemination and enhance the safety of the ADPJ.

Traumatic injury caused by explosive or blast events is traditionally divided into four mechanisms: primary, secondary, tertiary, and quaternary blast injury. The mechanisms of blast-induced traumatic brain injury (bTBI) are biomechanically distinct and can be modeled in both in vivo and in vitro systems. The primary bTBI injury mechanism is associated with the response of brain tissue to the initial blast wave. Among the four mechanisms of bTBI, there is a remarkable lack of information regarding the mechanism of primary bTBI. On the other hand, 30 years of research on the medical application of shock waves (SWs) has given us insight into the mechanisms of tissue and cellular damage in bTBI, including both air-mediated and underwater SW sources. From a basic physics perspective, the typical blast wave consists of a lead SW followed by shock-accelerated flow. The resultant tissue injury includes several features observed in primary bTBI, such as hemorrhage, edema, pseudo-aneurysm formation, vasoconstriction, and induction of apoptosis. These are well-described pathological findings within the SW literature. Acoustic impedance mismatch, penetration of tissue by shock/bubble interaction, geometry of the skull, shear stress, tensile stress, and subsequent cavitation formation are all important factors in determining the extent of SW-induced tissue and cellular injury. In addition, neuropsychiatric aspects of blast events need to be taken into account, as evidenced by reports of comorbidity and of some similar symptoms between physical injury resulting in bTBI and the psychiatric sequelae of post-traumatic stress. Research into blast injury biophysics is important to elucidate specific pathophysiologic mechanisms of blast injury, which enable accurate differential diagnosis, as well as development of effective treatments. Herein we describe the requirements for an adequate experimental setup when investigating blast-induced tissue and cellular injury; review SW physics, research, and the importance of engineering validation (visualization/pressure measurement/numerical simulation); and, based upon our findings of SW-induced injury, discuss the potential underlying mechanisms of primary bTBI.

In recent years, instances of neurotrauma in the elderly have been increasing. This article addresses the clinical characteristics, management strategy, and outcome in elderly patients with traumatic brain injury (TBI). Falls to the ground either from standing or from heights are the most common causes of TBI in the elderly, since both motor and physiological functions are degraded in the elderly. Subdural, contusional and intracerebral hematomas are more common in the elderly than the young as the acute traumatic intracranial lesion. High frequency of those lesions has been proposed to be associated with increased volume of the subdural space resulting from the atrophy of the brain in the elderly. The delayed aggravation of intracranial hematomas has been also explained by such anatomical and physiological changes present in the elderly. Delayed hyperemia/hyperperfusion may also be a characteristic of the elderly TBI, although its mechanisms are not fully understood. In addition, widely used pre-injury anticoagulant and antiplatelet therapies may be associated with delayed aggravation, making the management difficult for elderly TBI. It is an urgent issue to establish preventions and treatments for elderly TBI, since its outcome has been remained poor for more than 40 years.

In clipping surgery for aneurysmal subarachnoid hemorrhage (aSAH), critical steps include clot removal and dissection of aneurysms without premature rupture or brain injuries. To pursue this goal, a piezo actuator-driven pulsed water jet (ADPJ) system was introduced in this study. This study included 42 patients, who suffered aSAH and underwent clipping surgery. Eleven patients underwent surgery with the assistance of the ADPJ system (ADPJ group). In the other 31 patients, surgery was performed without the ADPJ system (Control group). The ADPJ system was used for clot removal and aneurysmal dissection. The clinical impact of the ADPJ system was judged by comparing the rate of premature rupture, degree of clot removal, and clinical outcomes. Intraoperatively, a premature rupture was encountered in 18.2 and 25.8% of cases in the ADPJ and control groups, respectively. Although the differences were not statistically significant, intraoperative observation suggested that the ADPJ system was effective in clot removal and dissection of aneurysms in a safe manner. Computed tomography scans indicated the achievement of higher degrees of clot removal, especially when the ADPJ system was used for cases with preoperative clot volumes of more than 25 ml (p = 0.047, Mann-Whitney U test). Clinical outcomes, including incidence of postoperative brain injury or symptomatic vasospasm, were similar in both groups. We described our preliminary surgical results using the ADPJ system for aSAH. Although further study is needed, the ADPJ system was considered a safe and effective tool for clot removal and dissection of aneurysms.

Background: Chronic subdural hematoma (CSDH) is a common neurosurgical disease. A subset of patients with CSDH may exhibit underlying spontaneous intracranial hypotension (SIH). Bilateral CSDH has a causal relationship with SIH, but there is no known causal relationship between unilateral CSDH and SIH.Case description: We encountered four cases of unilateral CSDH due to SIH. The patients' age ranged between 44 and 64 years; there were three males and one female. All patients presented with headache as their initial symptom, and then became comatose. Computed tomography demonstrated unilateral CSDH and transtentorial herniation in all patients. Treatments were emergency epidural blood patch (EBP) and evacuation of CSDH. The site of cerebrospinal fluid leak could not be identified in three patients; therefore, EBP was performed at upper and lower spine. All patients recovered from SIH; however, one patient experienced poor outcome due to Duret hemorrhage and ischemic complications of transtentorial herniation. Cranial asymmetry was present in all four patients, and unilateral CSDH was located on the side of the most curved cranial convexity.Conclusions: Unilateral CSDH, asymmetric cranial morphology, and transtentorial herniation in relatively young patients may indicate underlying SIH.

Background and Study Aims Various minimally invasive approaches are used in neurosurgery. Surgeons must perform nondynamic fine movements in a narrow corridor, so specially designed surgical devices are essential. Unsophisticated instruments may pose potential hazards. The purpose of this study was to assess the factors associated with muscle fatigue during minimally invasive neurosurgery and to investigate whether physical stress can be reduced by refining the devices used. Material and Methods Four physical aspects of a handpiece were investigated: torque of conduits (0.20, 0.28, and 0.37 kgf*cm), shape of hand grip (five types), angle of the nozzle (0, 20, and 40 degrees), and weight balance (neutral, proximal, and distal). To evaluate muscle fatigue, surface electromyography was recorded from the extensor carpi radialis muscle and flexor carpi radialis muscle during a geometric tracing task. The maximum voluntary contraction (MVC) of each muscle and %MVC (muscle contraction during a task/MVC × 100) were used as the indexes of muscle fatigue. Results The shape of the hand grip significantly reduced %MVC, which is associated with muscle fatigue. The torque of conduits and angle of the nozzle tended to reduce muscle fatigue but not significantly. Weight balance did not affect muscle fatigue. Based on these results, we made two refined models: model α (torque of conduits 0.2 kgf*cm, angle of nozzle 20 degrees, neutral balance, hand grip with a 2.9 × 2.0-cm oval section with angled finger rest), and model β (torque of conduits 0.2 kgf*cm, angle of nozzle 20 degrees, neutral balance, hand grip with a 2.9-cm round section with a curved finger rest). The %MVC was significantly decreased with both types (p Conclusions The geometrically refined surgical device can improve muscle load during surgery and reduce the surgeon's physical stress, thus minimizing the risk of complications.

A fundamental challenge of biology is to understand the vast heterogeneity of cells, particularly how cellular composition, structure, and morphology are linked to cellular physiology. Unfortunately, conventional technologies are limited in uncovering these relations. We present a real-time machine intelligence technology based on a radically new architecture that realizes real-time image-based intelligent cell search and sorting at an unprecedented rate. The technology integrates high-throughput cell imaging, cell focusing, and cell sorting on a hybrid software-hardware data management infrastructure, enabling real-time automated operation for data acquisition, data processing, decision making, and actuation. Specifically, we use it to demonstrate real-time sorting of microalgal and blood cells based on intracellular protein localization and cell-cell interaction from large heterogeneous populations for studying photosynthesis and atherothrombosis, respectively. Our technology is highly versatile and expected to enable machine-based scientific discovery in biological, pharmaceutical, and medical sciences.

Actuator-driven pulsed water-jet (ADPJ) dissection is an emerging surgical method for dissecting tissue without heat and mechanical injury to vessels. We elucidated the mechanical properties of the piezo ADPJ and evaluated its usefulness and safety in coronary artery bypass grafting procedures. The relationship between the input voltage (10-100 V) and peak pressure of the pulsed water jet was evaluated. The tissue strengths of swine internal thoracic and coronary arteries and the surrounding tissues were measured to assure tissue-selective dissection. Internal thoracic arteries were harvested by conventional electric cautery and the water jet in four swine, and eight coronary arteries surrounded by myocardium were attempted to be exposed with the water jet. The dissected specimens were histologically evaluated. The peak pressure of the pulsed water jet was positively correlated with the input voltage (R 2 = 0.9984, P

Paroxysmal sympathetic hyperactivity (PSH) is a distinct syndrome of episodic sympathetic hyperactivities following severe acquired brain injury, characterized by paroxysmal transient fever, tachycardia, hypertension, tachypnea, excessive diaphoresis and specific posturing. PSH remains to be an under-recognized condition with a diagnostic pitfall especially in the intensive care unit (ICU) settings due to the high prevalence of concomitant diseases that mimic PSH. A consensus set of diagnostic criteria named PSH-Assessment Measure (PSH-AM) has been developed recently, which is consisted of two components: a diagnosis likelihood tool derived from clinical characteristics of PSH, and a clinical feature scale assigned to the severity of each sympathetic hyperactivity. We herein present a case series of patients with PSH who were diagnosed and followed by using PSH-AM in our tertiary institutional medical and surgical ICU between April 2015 and March 2017 in order to evaluate the clinical efficacy of PSH-AM. Among 394 survivors of 521 patients admitted with acquired brain injury defined as acute brain injury at all levels of severity regardless of the presence of altered consciousness, including traumatic brain injury, stroke, infectious disease, and encephalopathy, 6 patients (1.5%) were diagnosed as PSH by using PSH-AM. PSH-AM served as a useful scoring system for early objective diagnosis, assessment of severity, and serial evaluation of treatment efficacy in the management of PSH in the ICU settings. In conclusion, critical care clinicians should consider the possibility of PSH and can use PSH-AM as a useful diagnostic and guiding tool in the management of PSH.

According to WHO, about 10 million new cases of thrombotic disorders are diagnosed worldwide every year. Thrombotic disorders, including atherothrombosis (the leading cause of death in the US and Europe), are induced by occlusion of blood vessels, due to the formation of blood clots in which aggregated platelets play an important role. The presence of aggregated platelets in blood may be related to atherothrombosis (especially acute myocardial infarction) and is, hence, useful as a potential biomarker for the disease. However, conventional high-throughput blood analysers fail to accurately identify aggregated platelets in blood. Here we present an in vitro on-chip assay for label-free, single-cell image-based detection of aggregated platelets in human blood. This assay builds on a combination of optofluidic time-stretch microscopy on a microfluidic chip operating at a high throughput of 10 000 blood cells per second with machine learning, enabling morphology-based identification and enumeration of aggregated platelets in a short period of time. By performing cell classification with machine learning, we differentiate aggregated platelets from single platelets and white blood cells with a high specificity and sensitivity of 96.6% for both. Our results indicate that the assay is potentially promising as predictive diagnosis and therapeutic monitoring of thrombotic disorders in clinical settings.

OBJECTIVEThe objective of this study was to test the hypothesis that midline (interhemispheric or perimesencephalic) traumatic subarachnoid hemorrhage (tSAH) on initial CT may implicate the same shearing mechanism that underlies severe diffuse axonal injury (DAI).METHODSThe authors enrolled 270 consecutive patients (mean age [± SD] 43 ± 23.3 years) with a history of head trauma who had undergone initial CT within 24 hours and brain MRI within 30 days. Six initial CT findings, including intraventricular hemorrhage (IVH) and tSAH, were used as candidate predictors of DAI. The presence of tSAH was determined at the cerebral convexities, sylvian fissures, sylvian vallecula, cerebellar folia, interhemispheric fissure, and perimesencephalic cisterns. Following MRI, patients were divided into negative and positive DAI groups, and were assigned to a DAI stage: 1) stage 0, negative DAI; 2) stage 1, DAI in lobar white matter or cerebellum; 3) stage 2, DAI involving the corpus callosum; and 4) stage 3, DAI involving the brainstem. Glasgow Outcome Scale–Extended (GOSE) scores were obtained in 232 patients.RESULTSOf 270 patients, 77 (28.5%) had DAI; tSAH and IVH were independently associated with DAI (p < 0.05). Of tSAH locations, midline tSAH was independently associated with both overall DAI and DAI stage 2 or 3 (severe DAI; p < 0.05). The midline tSAH on initial CT had sensitivity of 60.8%, specificity of 81.7%, and positive and negative predictive values of 43.7% and 89.9%, respectively, for severe DAI. When adjusted for admission Glasgow Coma Score, the midline tSAH independently predicted poor GOSE score at both hospital discharge and after 6 months.CONCLUSIONSMidline tSAH could implicate the same shearing mechanism that underlies severe DAI, for which midline tSAH on initial CT is a probable surrogate.

We developed a pulsed laser-induced liquid jet (LILJ) system to dissect tumor tissues while preserving fine blood vessels within deep and narrow working spaces and evaluated its utility and safety. However, the hand applicator of LILJ is heavy for the operator because of the torque generated by some of the accessories. Consequently, the operator cannot work with precision. To overcome this problem, we ergonomically redesigned the hand applicator of LILJ. Here, we report an assessment of the redesigned hand applicator’s usability and stability that were evaluated by using the torque generated around the center of gravity of the hand applicator and the hit probability. We considered the load on the hand by force measured using a force-sensitive sensor attached to the hand applicator. We showed that three out of five subjects were able to generate enough force equally to stabilize the position of the proposed hand applicator after a disturbance was generated and were able to reduce the force enough to control the disturbance.

Rationale and objectives Computed tomography (CT) plays a crucial role in early assessment of patients with traumatic brain injury (TBI). Marshall and Rotterdam are the mostly used scoring systems, in which CT findings are grouped differently. We sought to determine the scoring system and initial CT findings predicting the death at hospital discharge (early death) in patients with TBI. Materials and methods We included 245 consecutive adult patients with mild-to-severe TBI. Their initial CT and status at hospital discharge (dead or alive) were reviewed, and both CT scores were calculated. We examined whether each score was related to early death; compared the two scoring systems' performance in predicting early death, and identified the CT findings that are independent predictors of early death. Results More deaths occurred among patients with higher Marshall and Rotterdam scores (both P Conclusions Both Marshall and Rotterdam scoring systems can be used to predict early death in patients with TBI. The performance of the Marshall score is at least equal to that of the Rotterdam score. Thus, although older, the Marshall score remains useful in predicting patients' prognosis.

Background The piezo actuator-driven pulsed water jet (ADPJ) system is a novel surgical instrument that enables dissection of tissue without thermal damage. Using the ADPJ system in epilepsy surgery requires prediction of the tissue breaking strength of the epileptic brain. The aim of this study was to elucidate whether magnetic resonance imaging T2 relaxometry could predict the breaking strength. Methods A total of 12 patients with drug-resistant temporal lobe epilepsy who received surgical treatment were included in the study. All the patients qualified for surgery after a comprehensive preoperative evaluation for the treatment of epilepsy. T2 relaxation time, breaking strength of the hippocampus, and an anterior temporal lobe specimen obtained from surgery with dissection depth determined by the ADPJ system were examined. Results Preoperative T2 relaxation times of the anterior temporal lobe and hippocampus showed mild positive correlation with breaking strength (R2 = 0.60). The hippocampus showed higher T2 relaxation time than the temporal lobe. Hippocampal sclerosis seemed to have higher breaking strength than other pathologies, suggesting the correlation depends on the anatomical location and histopathology. The dissection depth of the extirpated lesion was negatively correlated with the breaking strength at input voltages of 10 V (R2 = − 0.34) and 20 V (R2 = − 0.20). Conclusions T2 relaxometry may be useful to predict tissue breaking strength in the epileptic brain that allows safe application of the ADPJ system in epilepsy surgery.

Background Surgery for intramedullary tumors is technically demanding because it requires surgical resection along with functional preservation of the spinal cord. The water jet dissector is an emerging tool in neurologic surgeries and a novel tool in spinal cord surgeries. This article evaluates the usefulness and safety of water jet dissection in an experimental study. Methods A pulsed water jet was applied to dissect the posterior median sulcus of the spinal cords of seven anesthetized pigs. In four pigs, the water jet was delivered on the dorsal spinal cord at different input voltages (5, 10, and 15 V) and for durations of either 15 or 30 seconds. The depth and dissected areas were measured histologically and compared. In three separate pigs, somatosensory evoked potentials (SEPs) were recorded before and after dissection (10 V for 30 seconds) to evaluate the function of the dorsal column sensory pathway. Results Increased pressure and duration of exposure to the pulsed water jet led to deeper and wider dissection of the dorsal spinal cord. Application of the water jet at 5 or 10 V allowed precise dissection along the dorsal columns along with the preservation of microvasculature. During SEP monitoring, responses were maintained after application of the water jet to the posterior column at 10 V for 30 seconds. Conclusions The pulsed water jet is a feasible option for spinal cord dissection. Characteristics of this water jet may help surgeons achieve complete resection of intramedullary tumors along with preserving satisfactory postoperative neurologic functions.

We compared Canadian computed tomography (CT) head rule (CCHR) and New Orleans Criteria (NOC) in predicting important CT findings in patients with mild traumatic brain injury (TBI). We included 142 consecutive patients with mild TBI [Glasgow coma scale (GCS) 13–15] who showed at least one of the risk factors stated in the CCHR or the NOC. We introduced two scores: a Canadian from the CCHR and a New Orleans from the NOC. A patient’s score represented a sum of the number of positive items. We examined the relationship between scores or items and the presence of important CT findings. Only the Canadian was significantly associated with important CT findings in multivariate analyses and showed higher area under the receiver operating characteristic curve (AUC) either in all 142 patients (GCS 13–15: P = 0.0130; AUC = 0.69) or in the 67 with a GCS = 15 (P = 0.0128, AUC = 0.73). Of items, “>60 years” or “≥65 years” included in either guideline was the strongest predictor of important CT finding, followed by “GCS

Purpose Primary blast-induced traumatic brain injury (bTBI) is the least understood of the four phases of blast injury. Distant injury induced by the blast wave, on the opposite side from the wave entry, is not well understood. This study investigated the mechanism of distant injury in bTBI. Materials and Methods Eight 8-week-old male Sprague–Dawley rats were divided into two groups: group 1 served as the control group and did not receive any shock wave (SW) exposure; group 2 was exposed to SWs (12.5 ± 2.5 MPa). Propagation of SWs within a brain phantom was evaluated by visualization, pressure measurement, and numerical simulation. Results Intracerebral hemorrhage near the ignition site and elongation of the distant nucleus were observed, despite no apparent damage between the two locations in the animal experiment. Visualization, pressure measurement, and numerical simulation indicated the presence of complex wave dynamics accompanying a sudden increase in pressure, followed by negative pressure in the phantom experiment. Conclusion A local increase in pressure above the threshold caused by interference of reflection and rarefaction waves in the vicinity of the brain–skull surface may cause distant injury in bTBI.

Background and Aim A current drawback of endoscopic submucosal dissection (ESD) for early-stage gastrointestinal tumors is the lack of instruments that can safely assist with this procedure. We have developed a pulsed jet device that can be incorporated into a gastrointestinal endoscope. Here, we investigated the mechanical profile of the pulsed jet device and demonstrated the usefulness of this instrument in esophageal ESD in swine. Methods The device comprises a 5-Fr catheter, a 14-mm long stainless steel tube for generating the pulsed water jet, a nozzle and an optical quartz fiber. The pulsed water jet was generated at pulse rates of 3 Hz by irradiating the physiological saline (4°C) within the stainless steel tube with an holmium-doped yttrium-aluminum-garnet (Ho:YAG) laser at 1.1 J/pulse. Mechanical characteristics were evaluated using a force meter. The device was used only for the part of submucosal dissection in the swine ESD model. Tissues removed using the pulsed jet device and a conventional electrocautery device, and the esophagus, were histologically examined to assess thermal damage. Results The peak impact force was observed at a stand-off distance of 40 mm (1.1 J/pulse). ESD using the pulsed jet device was successful, as the tissue specimens showed precise dissection of the submucosal layer. The extent of thermal injury was significantly lower in the dissected bed using the pulsed jet device. Conclusion The results showed that the present endoscopic pulsed jet system is a useful alternative for a safe ESD with minimum tissue injury.

Traumatic brain injury caused by explosive or blast events is traditionally divided into four phases: primary, secondary, tertiary, and quaternary blast injury. These phases of blast-induced traumatic brain injury (bTBI) are biomechanically distinct and can be modeled in both in vivo and in vitro systems. The primary bTBI injury phase represents the response of brain tissue to the initial blast wave. Among the four phases of bTBI, there is a remarkable paucity of information about the cause of primary bTBI. On the other hand, 30 years of research on the medical application of shockwaves (SW) has given us insight into the mechanisms of tissue and cellular damage in bTBI, including both air-mediated and underwater SW sources. From a basic physics perspective, the typical blast wave consists of a lead SW followed by supersonic flow. The resultant tissue injury includes several features observed in bTBI, such as hemorrhage, edema, pseudoaneurysm formation, vasoconstriction, and induction of apoptosis. These are well-described pathological findings within the SW literature. Acoustic impedance mismatch, penetration of tissue by shock/bubble interaction, geometry of the skull, shear stress, tensile stress, and subsequent cavitation formation, are all important factors in determining the extent of SW-induced tissue and cellular injury. Herein we describe the requirements for the adequate experimental set-up when investigating blast-induced tissue and cellular injury; review SW physics, research, and the importance of engineering validation (visualization/pressure measurement/numerical simulation); and, based upon our findings of SW-induced injury, discuss the potential underlying mechanisms of primary bTBI.

Object Shock waves have been experimentally applied to various neurosurgical treatments including fragmentation of cerebral emboli, perforation of cyst walls or tissue, and delivery of drugs into cells. Nevertheless, the application of shock waves to clinical neurosurgery remains challenging because the threshold for shock wave–induced brain injury has not been determined. The authors investigated the pressure-dependent effect of shock waves on histological changes of rat brain, focusing especially on apoptosis. Methods Adult male rats were exposed to a single shot of shock waves (produced by silver azide explosion) at over-pressures of 1 or 10 MPa after craniotomy. Histological changes were evaluated sequentially by H & E staining and terminal deoxynucleotidyl transferase–mediated deoxyuridine triphosphate nick-end labeling (TUNEL). The expression of active caspase-3 and the effect of the nonselective caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (Z-VAD-FMK) were examined to evaluate the contribution of a caspase-dependent pathway to shock wave–induced brain injury. High-overpressure (> 10 MPa) shock wave exposure resulted in contusional hemorrhage associated with a significant increase in TUNEL-positive neurons exhibiting chromatin condensation, nuclear segmentation, and apoptotic bodies. The maximum increase was seen at 24 hours after shock wave application. Low-overpressure (1 MPa) shock wave exposure resulted in spindle-shaped changes in neurons and elongation of nuclei without marked neuronal injury. The administration of Z-VAD-FMK significantly reduced the number of TUNEL-positive cells observed 24 hours after high-overpressure shock wave exposure (p < 0.01). A significant increase in the cytosolic expression of active caspase-3 was evident 24 hours after high-overpressure shock wave application; this increase was prevented by Z-VAD-FMK administration. Double immunofluorescence staining showed that TUNEL-positive cells were exclusively neurons. Conclusions The threshold for shock wave–induced brain injury is speculated to be under 1 MPa, a level that is lower than the threshold for other organs. High-overpressure shock wave exposure results in brain injury, including neuronal apoptosis mediated by a caspase-dependent pathway. This is the first report in which the pressure-dependent effect of shock wave on the histological characteristics of brain tissue is demonstrated.

Surgical revascularization for moyamoya disease prevents cerebral ischemic attacks by improving cerebral blood flow (CBF). But little is known about the change in intraoperative cerebral hemodynamics and its effect on postoperative neurological status, including symptomatic cerebral hyperperfusion. To address this issue, we applied a novel infrared imaging system (IRIS-V infrared imaging system) for intraoperative monitoring of surface hemodynamics in 2 patients with moyamoya disease. We investigated the correlation between clinical, radiological findings, and changes of the gradation value in infrared imaging using imaging software. The camera showed apparent revascularization during surgery in both cases. In case 1, a 36-year-old male who presented with transient ischemic attack (TIA) underwent superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis with pial synangiosis. His cerebrovascular reactivity was significantly compromised as shown by preoperative IMP-SPECT. Intraoperative infrared imaging disclosed an increase in brain surface temperature due to increase in blood flow around the anastomosis. The gradation value gradually increased after recanalization of bypass during several minutes. Postoperative IMP-SPECT showed a focal increase in CBF around the site of anastomosis 1 day after surgery. Beginning on the next day, he suffered fluctuated aphasia, numbness and fine movement disturbance on his right hand for 7 days. Intensive blood pressure control relieved his symptoms, and he was discharged without neurological deficit. The anatomical location and the temporal profile of hyperperfusion accorded with the neurological deficits. In case 2, a 29-year-old female who presented with TIA had already undergone surgical revascularization on the symptomatic right side. Then she underwent left STA-MCA anastomosis on the asymptomatic side with decreased cerebrovascular reserve capacity. Intraoperative infrared imaging disclosed no significant increase in brain surface color around the site of anastomosis except for the apparent revascularization through STA-MCA bypass. The gradation value did change significantly before or after recanalization of bypass. Postoperative IMP-SPECT showed a mild increase in CBF on the entire MCA territory without focal intense accumulation. Her postoperative course was uneventful, and she was discharged without neurological deterioration. Characteristic patterns of the intraoperative cerebral hemodynamics as delineated by IRIS-V may be the optimal predictor for postoperative transient symptomatic hyperperfusion after direct bypass in patients with moyamoya disease.

OBJECT Neuroendoscopic surgery allows minimally invasive surgery, but lacks effective methods to control bleeding. Water jet dissection with continuous flow has been used in liver and kidney surgery since the 1980s, and is effective for tissue manipulation with vascular preservation, but involves some potential risks, such as elevation of intracranial pressure during application in the ventricles. The authors previously reported the efficacy of the actuator-driven pulsed water jet device (ADPJ) to dissect soft tissue with vascular preservation in microscopic neurosurgery. This feasibility study investigated the use of the ADPJ to reduce the amount of water usage, leading to more safety with sustained efficacy. METHODS A small-diameter pulsed water jet device was developed for use with the flexible neuroendoscope. To identify the optimal conditions for the water jet, the flow rate, water pressure, and distance between the nozzle and target were analyzed in an in vitro study by using a gelatin brain phantom. A ventricle model was used to monitor the internal pressure and temperature. For ex vivo experiments the porcine brain was harvested and ventricle walls were exposed, and subsequently immersed into physiological saline. For in vivo experiments the cortex was microsurgically resected to make the small cortico-ventricle window, and then the endoscope was introduced to dissect ventricle walls. RESULTS In the in vitro experiments, water pressure was approximately 6.5 bar at 0.5 mm from the ADPJ nozzle and was maintained at 1 mm, but dropped rapidly toward 50% at 2 mm, and became 10% at 3.5 mm. The ADPJ required less water to achieve the same dissection depth compared with the continuous-flow water jet. With the ventricle model, the internal pressure and temperature were well controlled at the baseline, with open water drainage. These results indicated that the ADPJ can be safely applied within the ventricles. The ADPJ was introduced into a flexible endoscope and the ventricle walls were dissected in both the ex vivo and in vivo conditions. The ventricle wall was dissected without obscuring the view, and the vascular structures were anatomically preserved under direct application. Histological examination revealed that both the vessels on the ventricle wall and the fine vessels in the parenchyma were preserved. CONCLUSIONS The ADPJ can safely and effectively dissect the ventricle wall, with vascular preservation in immersed conditions. To achieve the optimal result of tissue dissection with minimal surgical risk, the ADPJ is a potential device for neuroendoscopic surgery of the ventricles.

Background A piezo actuator-driven pulsed water jet (ADPJ) system is a novel surgical instrument that enables dissection of tissue without thermal damage. It can potentially resect intra-axial lesions while preserving neurological function. Objective To report our first experience of applying an ADPJ system to brain and spinal cord cavernous malformations. Methods Four patients (2 women and 2 men, mean age 44.5 years) with brain (n = 3) and spinal cord (n = 1) cavernous malformations were enrolled in the study. All surgeries were performed with the aid of the ADPJ system. Postoperative neurological function and radiological findings were evaluated. Results The ADPJ system was useful in dissecting boundaries between the lesion and surrounding brain/spinal cord tissues. The pulsed water jet provided a clear surgical view and helped surgeons follow the margins. Water jet dissection peeled off the brain and spinal cord tissues from the lesion wall. Surrounding gliotic tissue was preserved. As a consequence, the cavernous malformations were successfully removed. Postoperative magnetic resonance imaging confirmed total removal of lesions in all cases. Preoperative neurological symptoms completely resolved in 2 patients. The others experienced partial recovery. No patients developed new postoperative neurological deficits; facial palsy temporarily worsened in 1 patient who underwent a suprafacial colliculus approach for the brainstem lesion. Conclusion The ADPJ provided a clear surgical field and enabled surgeons to dissect boundaries between lesions and surrounding brain and spinal cord gliotic tissue. The ADPJ system is a feasible option for cavernous malformation surgery, enabling successful tumor removal and preservation of neurological function.

Background Preservation of the hepatic vessels while dividing the parenchyma is key to achieving safe liver resection in a timely manner. In this study, we assessed the feasibility of a newly developed, piezo actuator-driven pulsed water jet (ADPJ) for liver resection in a surviving swine model. Methods Ten domestic pigs underwent liver resection. Parenchymal transection and vessel skeletonization were performed using the ADPJ (group A, n = 5) or an ultrasonic aspirator (group U, n = 5). The water jet was applied at a frequency of 400 Hz and a driving voltage of 80 V. Physiological saline was supplied at a flow rate of 7 ml/min. After 7 days, the animals were killed and their short-term complications were examined and compared between the two groups. Results No significant complications, such as massive bleeding, occurred in either group during the surgical procedures. The transection time per transection area was significantly shorter in group A than in group U (1.5 ± 0.3 vs. 2.3 ± 0.5 min/cm2, respectively, P = 0.03). Blood loss per transection area was not significantly different between groups A and U (9.3 ± 4.2 vs. 11.7 ± 2.3 ml/cm2, P = 0.6). All pigs in group A survived for 7 days. No postoperative bleeding or bile leakage was observed in any animal at necropsy. Conclusion The present results suggested that the ADPJ reduces transection time without increasing blood loss. ADPJ is a safe and feasible device for liver parenchymal transection.

Objective The pulsed laser-induced liquid jet (LILJ) system is an emerging surgical instrument intended to assist both maximal removal of the lesion and functional maintenance through preservation of fine vessels and minimal damage to the surrounding tissue. The system ejects the minimum required amount of pulsed water through a handy bayonet-shaped catheter. We have already shown a significant increase in removal rate, in addition to a noteworthy reduction of intraoperative blood loss and procedure time in the treatment of large pituitary and skull base tumors in a single-institution series. The present study evaluated the safety of the system in multiple institutions. Methods The study included 46 patients, 29 men and 17 women (mean age: 59.1 years) who underwent microsurgical/endoscopic resection of lesions in or in the vicinity of the pituitary fossa through the transsphenoidal approach between October 2011 and June 2012 at six institutions. The histologic diagnoses were pituitary adenoma (31 cases), meningioma (4), craniopharyngioma (3), cavernous angioma (2), and Rathke cyst cleft (1). Lesion volume ranged from 2.0 to 30.4 cm 3 (mean: 3.7 cm 3 ). Cavernous sinus invasion was observed in 11 cases and suprasellar extension in 29 cases. Results Preservation of intralesional arteries (diameter: 150 µm) was achieved in all situations in > 80% of cases. Intended surgical steps were achieved except for some restrictions in motion due to the use of an optical quartz fiber. No complications occurred directly related to the use of the device. Conclusions The LILJ system can be used for safe removal of lesions in or in the vicinity of the pituitary fossa.

1. Investigation of shock wave-induced phenomenon: blast-induced traumatic brain injury Blast wave (BW) is generated by explosion and is comprised of lead shock wave (SE) followed by subsequent supersonic flow.

Paper deals with applications of underwater shock waves to medicine. A historical development of underwater shock wave generation by using pulsed Ho:YAG laser beam irradiation in water is briefly described and an overview is given regarding potential applications of shock waves to neuro-surgery. The laser beam irradiation in a liquid-filled catheter produces water vapor bubble and shock waves intermittently produces micro-liquid jets in a controlled fashion from the exit of the catheter. Correlations between shock dynamics and bubble dynamics are emphasized. To optimize the jet motion, results of basic parametric studies are briefly presented. The liquid jet discharged from the catheter exit has an impulse high enough to clearly exhibit effectiveness for various medical purposes. In liquid jets we observed reasonably strong shock waves and hence invented a compact shock generator aiming to apply to microsurgery. We applied it to a rat's bone window and developed an effective method of brain protection against shock loading. The insertion of Gore-Tex® sheet is found to attenuate shock waves drastically even for very short stand off distance and its physical mechanism is clarified. The laser-induced liquid jet (LILJ) is successfully applied to soft tissue dissection. Animal experiments were performed and results of histological observations are presented in details. Results of animal experiments revealed that LILJ can sharply dissect soft tissue with a minimum amount of liquid consumption, while blood vessels larger than 0.2 mm in diameter are preserved. Shock waves and LILJ have a potential to be indispensable tools in neuro-surgery.

PURPOSE To report on the effectiveness and safety of an ophthalmic piezoelectric actuator-driven pulsed water jet (ADPJ) system adapted for intraocular use. METHODS First, we determined the highest ADPJ flow rate that did not cause an unsafe rise in intraoperative intraocular pressure (IOP) in rabbits (n = 4). Next, we determined the most effective ADPJ frequency (in hertz) at that flow rate. Finally, we visualized the ADPJ stream, measured its pressure, and determined the minimum voltage and distance between the ADPJ needle and retinal veins to induce intravenous displacement of the blood column (DBC) through massage of the outer retinal vessels (n = 3) while not causing retinal tearing or hemorrhage. RESULTS We found that a 0.05 mL/min ADPJ flow rate caused IOP to rise above 40 mm Hg after 1 minute, but that at 0.025 mL/min, IOP stayed below 40 mm Hg even after 3 minutes. Moreover, we found that a 0.025 mL/min ADPJ stream was stable at a pulse frequency of 10 Hz and that at this flow rate/frequency the ADPJ pressure was closely correlated with the applied voltage (P < 0.001, r2 = 0.9991). The minimum voltage and distance to achieve intravenous DBC without causing retinal tearing or hemorrhage were 40 V and 0.5 mm, respectively. CONCLUSIONS With an appropriate flow rate and surgical time, ADPJ successfully induced massage of the retinal vessels and intravenous DBC while maintaining safe IOP and not causing retinal complications. TRANSLATIONAL RELEVANCE The ADPJ system has promise as a safe and minimally invasive instrument for the intraocular surgical treatment of human retinal vascular diseases.

ObjectiveThis study aimed to clarify the management of emergency electric power and the operation of radiology diagnostic devices after the Great East Japan Earthquake.MethodsTiming of electricity restoration, actual emergency electric power generation, and whether radiology diagnostic devices were operational and the reason if not were investigated through a questionnaire submitted to all 14 disaster base hospitals in Miyagi Prefecture in February and March 2013.ResultsCommercial electricity supply resumed within 3 days after the earthquake at 13 of 14 hospitals. Actual emergency electric power generation was lower than pre-disaster estimates at most of the hospitals. Only 4 of 11 hospitals were able to generate 60% of the power normally consumed. Under emergency electric power, conventional X-ray and computed tomography (CT) scanners worked in 9 of 14 (64%) and 8 of 14 (57%) hospitals, respectively. The main reason conventional X-ray and CT scanners did not operate was that hospitals had not planned to use these devices under emergency electric power. Only 2 of the 14 hospitals had a pre-disaster plan to allocate emergency electric power, and all devices operated at these 2 hospitals.ConclusionsPre-disaster plans to allocate emergency electric power are required for disaster base hospitals to effectively operate radiology diagnostic devices after a disaster. (Disaster Med Public Health Preparedness. 2014;8:548-552)

Background and objective Although improvements of spatial and temporal resolution in infrared (IR) imaging have enabled intraoperative real-time acquisition of physiological and pathological information on living organs, the imaging qualities of anatomical delineation of blood vessels and functional delineation of blood flow were insufficient to serve as visual monitoring. The main reason was partly due to the lack of an appropriate IR detection IR band (formerly 3 - 5 micro m), and the broad dynamic range in previous modalities. Methods To make a good contrast between blood vessels and surrounding tissues, the detection wavelength was shifted to the long-wave (7 - 14 micro m) part of IR spectrum, which includes the peak IR wave from living tissue (9 - 10 micro m), and the dynamic range was confined to +/- 10 degrees C around 35 degrees C. The novel camera system (IRIS IV infrared imaging system) was used for the visual monitoring of blood flow during the obliteration of a spinal perimedullary arteriovenous fistula at Th 7 in 71-year-old male patient. The temperature resolution of camera was 0.15 degrees C, with its intensity resolution of 16 bit (320 x 240 pixels), and data were stored at a rate of 30 frames/second. High-quality delineation of blood vessels and blood flow was obtained all through the procedure without use of cold saline, which was an inevitable procedure to make contrast in the previously used thermography. However, the occasional use of an air blower was helpful to achieve adequate images in the deep and narrow area of the surgical field. The amount of shunt flow reduction was visualized by the intensity in the acquired imaging, which was also confirmed later by digital subtraction angiography. Conclusion From the present experience, it is considered that this type of imaging may be able to substitute intraoperative blood vessel and blood flow monitoring in spinal and other neurosurgical disorders.

Background and Objectives Although water jet technology has been considered as a feasible neuroendoscopic dissection methodology because of its ability to perform selective tissue dissection without thermal damage, problems associated with continuous use of water and the ensuing fountain-effect—with catapulting of the tissue—could make water jets unsuitable for endoscopic use, in terms of safety and ease of handling. Therefore, the authors experimented with minimization of water usage during the application of a pulsed holmium:yttrium-aluminum-garnet (Ho:YAG) laser-induced liquid jet (LILJ), while assuring the dissection quality and the controllability of a conventional water jet dissection device. We have developed the LILJ generator for use as a rigid neuroendoscope, discerned its mechanical behavior, and evaluated its dissection ability using the cadaveric rabbit ventricular wall. Study Design/Materials and Methods The LILJ generator is incorporated into the tip of a stainless steel tube (length: 22 cm; internal diameter: 1.0 mm; external diameter: 1.4 mm), so that the device can be inserted into a commercial, rigid neuroendoscope. Briefly, the LILJ is generated by irradiating an internally supplied water column within the stainless steel tube using the pulsed Ho:YAG laser (wave length: 2.1 μm, pulse duration time: 350 microseconds) and is then ejected through the metal nozzle (internal diameter: 100 μm). The Ho:YAG laser pulse energy is conveyed through optical quartz fiber (core diameter: 400 μm), while cold water (5°C) is internally supplied at a rate of 40 ml/hour. The relationship between laser energy (range: 40–433 mJ/pulse), standoff distance (defined as the distance between the tip of the optical fiber and the nozzle end; range: 10–30 mm), and the velocity, shape, pressure, and average volume of the ejected jet were analyzed by means of high-speed camera, PVDF needle hydrophone, and digital scale. The quality of the dissection plane, the preservation of blood vessels, and the penetration depth were evaluated using five fresh cadaveric rabbit ventricular walls, under neuroendoscopic vision. Results Jet velocity (7.0–19.6 m/second) and pressure (0.07–0.28 MPa) could be controlled by varying the laser energy, which determined the penetration depth in the cadaveric rabbit ventricular wall (0.07–1.30 mm/shot). The latter could be cut into desirable shapes—without thermal effects—under clear neuroendoscopic vision. The average volume of a single ejected jet could be confined to 0.42–1.52 μl/shot, and there was no accompanying generation of shock waves. Histological specimens revealed a sharp dissection plane and demonstrated that blood vessels of diameter over 100 μm could be preserved, without thermal damage. Conclusions The present pulsed LILJ system holds promise as a safe and reliable dissection device for deployment in a rigid neuroendoscope. Lasers Surg. Med. 34:227–234, 2004. © 2004 Wiley-Liss, Inc.

Joint development of a laser monitor for the real-time bio-tissue analysis is presented. The monitor is based on the digital dynamic laser speckle photography and deals with soft and hard bio-tissues. In soft tissues, the dynamic bio-speckles are formed in a scattered from a tissue laser light. An optically transparent model of hard bio-tissue was prepared and preliminary analysis of a stress field in the stressed model was performed using the dependence of the refractive index of transparent solids upon the state of stress and the double exposure speckle photography data. The refractive index of the stressed material was evaluated and the state of stress was reconstructed using the stress-optical law.

The attenuation of an underwater shock wave by a thin porous layer is studied both experimentally and numerically. The shock waves are generated by exploding 10 mg silver azide pellets and the pressures at different distances from the explosion center are measured. Measurements are also carried out with a gauze layer placed between the explosion source and the pressure gauge. The results with and without the gauze layer are compared evaluating the shock wave attenuation. Numerical simulations of the phenomenon are also carried out for a simple wave attenuation model. The results are compared with the experimental data. Despite the simple mathematical model of wave attenuation, the agreement between the experimental and numerical results is reasonable.