Choosing a laser for laser speckle contrast imaging

The use of laser speckle contrast imaging (LSCI) has expanded rapidly for characterizing the motion of scattering particles. Speckle contrast is related to the dynamics of the scattering particles via a temporal autocorrelation function, but the quality of various elements of the imaging system can adversely affect the quality of the signal recorded by LSCI. While it is known that the laser coherence affects the speckle contrast, it is generally neglected in in vivo LSCI studies and was not thoroughly addressed in a practical matter. In this work, we address the question of how the spectral width of the light source affects the speckle contrast both experimentally and through numerical simulations. We show that commonly used semiconductor laser diodes have a larger than desired spectral width that results in a significantly reduced speckle contrast compared with ideal narrow band lasers. This results in a reduced signal-to-noise ratio for estimating changes in the motion of scattering particles. We suggest using a volume holographic grating stabilized laser diode or other diodes that have a spectrum of emitted light narrower than ≈1 nm to improve the speckle contrast.D.D. Postnov was supported by grant NNF17OC0025224 awarded by Novo Nordisk Foundation, Denmark. Support was also provided by NIH R01-MH111359, R01-EB021018, and R01-NS108472. (NNF17OC0025224 - Novo Nordisk Foundation, Denmark; R01-MH111359 - NIH; R01-EB021018 - NIH; R01-NS108472 - NIH)https://www.nature.com/articles/s41598-019-39137-xPublished versionPublished versio

Chronic cranial windows for long term multimodal neurovascular imaging in mice

Chronic cranial windows allow for longitudinal brain imaging experiments in awake, behaving mice. Different imaging technologies have their unique advantages and combining multiple imaging modalities offers measurements of a wide spectrum of neuronal, glial, vascular, and metabolic parameters needed for comprehensive investigation of physiological and pathophysiological mechanisms. Here, we detail a suite of surgical techniques for installation of different cranial windows targeted for specific imaging technologies and their combination. Following these techniques and practices will yield higher experimental success and reproducibility of results.R21 EY030727 - NEI NIH HHS; R01 NS108472 - NINDS NIH HHS; R01 NS057198 - NINDS NIH HHS; K99 AG063762 - NIA NIH HHS; R01 DA050159 - NIDA NIH HHS; R01 EB021018 - NIBIB NIH HHS; R01 MH111359 - NIMH NIH HHSPublished versio

Pain as a First Manifestation of Paraneoplastic Neuropathies: A Systematic Review and Meta-Analysis.

INTRODUCTION: Paraneoplastic neurological syndromes (PNS) consist of a heterogeneous group of neurological disorders triggered by cancer. The aim of this systematic review is to estimate the reported prevalence of pain in patients with paraneoplastic peripheral neuropathy (PPN). METHODS: A systematic computer-based literature search was conducted on PubMed database. RESULTS: Our search strategy resulted in the identification of 126 articles. After the eligibility assessment, 45 papers met the inclusion criteria. Full clinical and neurophysiological data were further extracted and involved 92 patients with PPN (54.5% males, mean age 60.0 ± 12.2 years). The commonest first manifestation of PPN is sensory loss (67.4%), followed by pain (41.3%), weakness (22.8%), and sensory ataxia (20.7%). In 13.0% of the cases, pain was the sole first manifestation of the PPN. During the course of the PPN, 57.6% of the patients may experience pain secondary to the neuropathy. CONCLUSIONS: Pain is very prevalent within PPN. Pain specialists should be aware of this. Detailed history-taking, full clinical examination, and requesting nerve conduction studies might lead to an earlier diagnosis of an underlying malignancy

Enzymatic debridement of deep partial thickness burn wounds with collagenase in children [Çocuklarda derin kismi kalinliktaki yanik yarasinin kollajenaz ile enzimatik debridmani]

Thirty-nine pediatric burn patients treated by enzymatic debridement with Collagenase Clostridiopeptidase A (CCA), were compared to 27 patients whose burn wounds were excised surgically. In all patients, burn wounds were initially assessed as deep partial-thickness during admission. Total removal of eschar was achieved in 25 of 39 (64%) patients by CCA only (Group D). In 14 patients (36%), therapy with CCA was ceased because of the development of burn wound infection or a manifest need for grafting of the wound, therefore, these patients underwent tangential wound excision (Group DS). The records of 27 patients, treated by early tangential excision, having similar burn wounds by extent and depth with Group D and DS were used as controls (Group S). There was no significant difference between the time to achieve a clean wound bed in Group D, DS, and S (mean 7.4, 7.1, and 6.9 days respectively, p>0.05). In Group D, none of the patients required blood transfusion, except one. Patients in Group DS were found to have fewer excisions (mean 1.14) when compared to those in Group S (mean 1.55, p<0.05). The shortest hospital stay was found in Group D (12.2 days, p<0.01). In conclusion, the use of CCA, provided a short hospital stay, reduced the overall need for surgery and blood transfusions, in patients with deep dermal burns. Thus, CCA should be considered as an initial treatment of choice for the removal of eschar in children, having a burn wound without infection, and assessed as deep partial-thickness, at admission

Cardiac pulsatility mapping and vessel type identification using laser speckle contrast imaging

Systemic flow variations caused by the cardiac cycle can play a role or be an important marker in both normal and pathological conditions. The shape, magnitude and propagation speed of the flow pulse reflect mechanical properties of the vasculature and are known to vary significantly with vascular diseases. Most conventional techniques are not capable of imaging cardiac activity in the microcirculation due to spatial and/or temporal resolution limitations and instead make inferences about propagation speed by making measurements at two points along an artery. Here, we apply laser speckle contrast imaging to images with high spatial resolution in the high frequency harmonics of cardiac activity in the cerebral cortex of a mouse. We reveal vessel dependent variation in the cardiac pulse activity and use this information to automatically identify arteries and veins.Novo Nordisk Foundation, Denmark (NNF17OC0025224); National Institutes of Health (NIH) (R01-MH111359, R01-EB021018, and R01-NS108472). (NNF17OC0025224 - Novo Nordisk Foundation, Denmark; R01-MH111359 - National Institutes of Health (NIH); R01-EB021018 - National Institutes of Health (NIH); R01-NS108472 - National Institutes of Health (NIH))https://www.osapublishing.org/boe/abstract.cfm?uri=boe-9-12-6388Published versio

Pentoxifylline does not prevent hypoxia/reoxygenation-induced necrotizing enterocolitis: An experimental study

PubMed ID: 15017117Hypoxia/reoxygenation (H/R)-induced intestinal injury plays a significant role in the development of necrotizing enterocolitis (NEC). We experimentally explored the effect of pentoxifylline (PTX) on an NEC model. Twenty-one newborn rabbits were divided into three groups: group 1 (control), group 2 (H/R) and group 3 (H/R + PTX). Five minutes of reoxygenation following 5 min of hypoxia was performed three times a day during 3 days. Before each H/R procedure in the H/R + PTX group, the rabbits were treated with PTX 25 mg/kg intraperitoneally. Animals were sacrificed on the third day and ileum samples were taken for histopathological examination and biochemical enzyme studies [superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione S-transferase (GST)]. There was a significant difference in the grade and number of the intestinal lesions between controls and the H/R and H/R + PTX groups (p 0.05). Intestinal SOD, GR and GST activities in the H/R and H/R + PTX groups were significantly higher than in the control group (p 0.05). Significantly reduced GPx activity was found in the H/R and H/R + PTX groups compared with the controls (p 0.05). Ischemia/reperfusion injury was responsible for mediating hypoxia-induced intestinal necrosis in NEC and PTX pretreatment did not have a protective effect on NEC. Copyright © 2004 S. Karger AG, Basel

Hemorrhagic shock and bacterial translocation

Background: Bacterial translocation (BT) is increased under some circumstances. It is believed that xanthine oxidase generated oxidants may play a major role in promoting bacterial translocation by disrupting mucosal barrier function in hemorrhagic shock. The aim of this study is to determine the effects of free oxygen radicals on hemorrhagic shock induced bacterial translocation, and phagocytic burst activity status after shed blood resuscitation. Material and Methods: We studied the effects of free oxygen radicals in hemorrhagic shock induced intestinal mucosal injury and its role on bacterial translocation, and nonspecific host immune defense status in hemorrhagic shock in 36 male albino rats. In the control group (group I, n = 12 rats), rats were not exposed to any manipulation. In the sham group (group II, n = 12 rats), rats were catheterized, but blood was not withdrawn. In the shock group (group III, n = 12 rats), rats were subjected to 30 minutes of hemorrhagic shock (mean arterial pressure, 30-35 mmHg) followed by reinfusion of shed blood. Twenty-four hours after hemorrhage and reinfusion, the mesenteric lymph node, liver, spleen, peritoneum, cecum, and blood samples were harvested from each animal for bacterial culture. Ileum were examined histopathologically, ileal mucosas were examined biochemically, and blood samples were examined immunologically. Results: The weights were similar in all groups, and no difference in both gram-negative and total number of bacteria found in cecal stool cultures between all groups was found. Bacterial translocation was observed in group III (25%). Tissue glutathione reductase (GR), Glutathione-S transferase (GST) levels, as a free oxygen radical indicator, were higher in group III than in groups I and II (P < 0.05). Epithelial pathological changes observed in group III were significantly greater than the other groups (P < 0.05), and phagocytic burst activity was significantly increased in group III (P < 0.05). Conclusion: Hemorrhagic shock promotes bacterial translocation by means of free oxygen radicals that produce epithelial changes, and shed blood resuscitation increases phagocytic burst activity. INTRODUCTION Despite technological development, posttraumatic and postoperative sepsis still remain major causes of morbidity and mortality. Clinical and experimental studies have shown that indigenous bacteria can translocate to systemic organs and cause systemic infections, a process termed bacterial translocation (BT). BT is increased under certain circumstances such as hemorrhagic shock, antibiotic therapy, total parenteral nutrition, intestinal obstruction, thermal injury, malnutrition, elemental diets, cytotoxic drugs, etc. It is believed that xanthine oxidase generated oxidants may play a major role in promoting bacterial translocation by disrupting mucosal barrier function in hemorrhagic shock. The aim of this study is to determine the effects of free oxygen radicals on hemorrhagic shock induced bacterial translocation, and phagocytic burst activity status after shed blood resuscitation

Pentoxifylline does not prevent hypoxia/reoxygenation-induced necrotizing enterocolitis - An experimental study

WOS: 000222387700006PubMed ID: 15017117Hypoxia/reoxygenation (H/R)-induced intestinal injury plays a significant role in the development of necrotizing enterocolitis (NEC). We experimentally explored the effect of pentoxifylline (PTX) on an NEC model. Twenty-one newborn rabbits were divided into three groups: group 1 ( control), group 2 (H/R) and group 3 (H/R + PTX). Five minutes of reoxygenation following 5 min of hypoxia was performed three times a day during 3 days. Before each H/R procedure in the H/R + PTX group, the rabbits were treated with PTX 25 mg/kg intraperitoneally. Animals were sacrificed on the third day and ileum samples were taken for histopathological examination and biochemical enzyme studies [superoxide dismutase ( SOD), glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione S-transferase (GST)]. There was a significant difference in the grade and number of the intestinal lesions between controls and the H/R and H/R + PTX groups (p 0.05). Significantly reduced GPx activity was found in the H/R and H/R + PTX groups compared with the controls (p 0.05). Ischemia/reperfusion injury was responsible for mediating hypoxia-induced intestinal necrosis in NEC and PTX pretreatment did not have a protective effect on NEC. Copyright (C) 2004 S. Karger AG, Basel