Low-volume resuscitation with normal saline is associated with microvascular endothelial dysfunction after hemorrhage in rats, compared to colloids and balanced crystalloids.

BACKGROUND: Restoration of endothelial glycocalyx (EG) barrier may be an essential therapeutic target for successful resuscitation. The aim of this study was to compare in vivo the effects of resuscitation with normal saline (NS) to lactated Ringer's solution (LR), 5% albumin and fresh frozen plasma (FFP) on their ability to maintain EG and barrier function integrity, mitigate endothelial injury and inflammation, and restore vascular homeostasis after hemorrhagic shock. METHODS: Anesthetized rats (N = 36) were subjected to hemorrhagic shock (bled 40% of total blood volume), followed by resuscitation with 45 ml/kg NS or LR, or 15 ml/kg 5% albumin or FFP. Microhemodynamics, EG thickness, permeability, leukocyte rolling and adhesion were assessed in >180 vessels from cremaster muscle, as well as systemic measures. RESULTS: After hypotensive resuscitation, arterial pressure was 25% lower than baseline in all cohorts. Unlike FFP, resuscitation with crystalloids failed to restore EG thickness to baseline post shock and shedding of glycocalyx proteoglycan was significantly higher after NS. NS decreased blood flow and shear, and markedly increased permeability and leukocyte rolling/adhesion. In contrast, LR had lesser effects on increased permeability and leukocyte rolling. Albumin stabilized permeability and white blood cell (WBC) rolling/adhesion post shock, comparable to FFP. CONCLUSIONS: Resuscitation with NS failed to inhibit syndecan-1 shedding and to repair the EG, which led to loss of endothelial barrier function (edema), decline in tissue perfusion and pronounced leukocyte rolling and adhesion. Detrimental effects of NS on endothelial and microvascular stabilization post shock may provide a pathophysiological basis to understand and prevent morbidity associated with iatrogenic resuscitation after hemorrhagic shock.

Plasma syndecan-1 and heparan sulfate correlate with microvascular glycocalyx degradation in hemorrhaged rats after different resuscitation fluids.

The endothelial glycocalyx plays an essential role in many physiological functions and is damaged after hemorrhage. Fluid resuscitation may further change the glycocalyx after an initial hemorrhage-induced degradation. Plasma levels of syndecan-1 and heparan sulfate have been used as indirect markers for glycocalyx degradation, but the extent to which these measures are representative of the events in the microcirculation is unknown. Using hemorrhage and a wide range of resuscitation fluids, we studied quantitatively the relationship between plasma biomarkers and changes in microvascular parameters, including glycocalyx thickness. Rats were bled 40% of total blood volume and resuscitated with seven different fluids (fresh whole blood, blood products, and crystalloids). Intravital microscopy was used to estimate glycocalyx thickness in >270 postcapillary venules from 58 cremaster preparations in 9 animal groups; other microvascular parameters were measured using noninvasive techniques. Systemic physiological parameters and blood chemistry were simultaneously collected. Changes in glycocalyx thickness were negatively correlated with changes in plasma levels of syndecan-1 (r = -0.937) and heparan sulfate (r = -0.864). Changes in microvascular permeability were positively correlated with changes in both plasma biomarkers (r = 0.8, P < 0.05). Syndecan-1 and heparan sulfate were also positively correlated (r = 0.7, P < 0.05). Except for diameter and permeability, changes in local microcirculatory parameters (red blood cell velocity, blood flow, and wall shear rate) did not correlate with plasma biomarkers or glycocalyx thickness changes. This work provides a quantitative framework supporting plasma syndecan-1 and heparan sulfate as valuable clinical biomarkers of glycocalyx shedding that may be useful in guiding resuscitation strategies following hemorrhage.

Chronic exposure of lung alveolar epithelial type II cells to tobacco-specific carcinogen NNK results in malignant transformation: a new in vitro lung carcinogenesis model.

Lung cancer is the leading cause of cancer-related mortality in both men and women throughout the world. This disease is strongly associated with tobacco smoking. The aim of this manuscript was to establish an in vitro model that mimics the chronic exposures of alveolar epithelial type II cells to the tobacco-specific nitrosamine carcinogen, NNK. Immortalized non-neoplastic alveolar epithelial cells type II, (E10 cells), from BALB/c mice were exposed to low concentration of NNK (100 pM) during 5, 10, 15, and 20 cycles of 48 h. NNK-transformed cells showed an increase of proliferation rate and motility. Moreover, these cells underwent epithelial-to-mesenchymal transition (EMT). Increased migratory capacity and EMT were correlated to the time of exposure to NNK. NNK-transformed cells were tested for their growth and metastatic capacity in vivo. Subcutaneous injection of cells exposed to NNK for 20 cycles (E10-NNK20 clone) into BALB/c mice led to the formation of subcutaneous tumors that arose after 40 ± 17 d in all animals, which died 95 ± 18 d after cell inoculation, with lymph nodes and lung metastasis. The morphological characteristics of tumors were compatible with metastatic undifferentiated carcinoma. Cells exposed to NNK for 5-10 cycles did not display metastatic capacity, while those exposed for 15 cycles displayed low capacity. Our results show that prolonged exposures to NNK led the cells to increasingly acquire malignant properties. The cellular model presented in this study is suitable for studying the molecular events involved in the different stages of malignant transformation.

Effects of perfluorocarbon emulsions on microvascular blood flow and oxygen transport in a model of severe arterial gas embolism.

BACKGROUND: Arterial gas embolism (AGE) is a clinical problem that occurs directly in cardiopulmonary bypass machines in open-heart surgeries, or indirectly (through cardiac or pulmonary right to left shunts) in dive accidents, resulting in serious morbidity and even death. Perfluorocarbon (PFC) emulsions have been used for the treatment of AGE in an animal model. We hypothesized that PFC emulsions enhance microvascular blood flow, speed bubble resolution, and oxygenation in AGE compared with saline in a model of cremaster muscle from anesthetized rats. MATERIALS AND METHODS: AGE was induced by direct air injection into the femoral artery ipsilateral to the studied cremaster muscle. Microhemodynamics, microvascular, and tissue oxygenation were determined before and after treatment with two different commercial PFC emulsions (C10F20, Oxycyte; Oxygen Biotherapeutics, Inc and C10F18, PHER-O2; Sanguine Corporation, Inc) compared with saline in real time using brightfield and phosphorescence microscopy. RESULTS: Blood pressure and heart rate remained unchanged. Systemic PO2, oxygen (O2) content, and glucose were higher in PFC groups, whereas hematocrit dropped in all groups. Arteriolar blood flow went up 85% and 80% of baseline after C10F20 and C10F18 treatments, respectively, versus 11% after saline treatment. Arteriolar and tissue PO2, and O2 delivery were higher in PFC groups compared with the control group. There was an increase in arteriolar blood flow, reduction in diffusional resistance of O2 in the plasma, and improved tissue oxygenation. CONCLUSIONS: Administration of PFC emulsions in AGE is superior to saline primarily because of surfactant properties along with air bubble reabsorption.

Incidence of Intra-abdominal Adhesions Following Intraperitoneal Injection of Hemostatic Products in Rabbits.

INTRODUCTION: Definitive management of non-compressible intra-abdominal hemorrhage (NCIAH) currently requires a surgeon and operating room capable of performing damage control surgery. In a wartime scenario or a geographically remote environment, these may not be readily available. In this study, we sought to test the safety of 2 emerging injectable hemostatic agents (CounterFlow and Fast Onset Abdominal Management, or FOAM, poloxamer component) versus normal saline control over a prolonged monitoring duration following administration by a non-surgical provider. MATERIALS AND METHODS: The Institutional Animal Care and Use Committee approved all research conducted in this study. We randomized male New Zealand white rabbits into 2 monitoring cohorts of 24 hours and 2 weeks. Each cohort contained 3 treatment groups (n = 4 rabbits/group): CounterFlow, the testable poloxamer component of FOAM, and normal saline control. We injected each treatment intraperitoneally in the left lower abdominal quadrant. Doses were 15 mL/kg for CounterFlow, 6.3 mL/kg for the poloxamer component of FOAM, and 15 mL/kg for normal saline. We conducted all injections under isoflurane anesthesia monitored by trained veterinary staff. Animals were euthanized at each cohort end point, and a veterinary pathologist blinded to treatment type performed necropsy. The primary outcome was incidence of intra-abdominal adhesions at necropsy. Quantitatively, adhesions when present were graded by the veterinary pathologist on a 1 to 4 scale, where "1" represented adhesions involving from 1 to 25% of the examined abdomen, "2" represented from 26 to 50%, "3" represented from 51 to 75%, and "4" represented from 76 to 100%. Qualitatively, adhesions present were graded by degree ("1" = minimal, "2" = mild, "3" = moderate, and "4" = severe) and chronicity ("1" = acute, "2" = subacute, and "3" = chronic). We also drew d-dimer blood values and measured body weights for each animal. Statistical analysis included either repeated measures 2-way ANOVA or a mixed-effects model (in the case of missing data) with Geisser-Greenhouse correction. We adjusted multiple comparisons using Tukey statistical hypothesis tests. RESULTS: In the 2-week cohort, 3 CounterFlow animals showed adhesions judged to be "1" quantitatively. Qualitatively, 2 of these were assessed as "1" for degree of adhesions and the other demonstrated a "2." On the chronicity of adhesions scale, 1 animal demonstrated a "2" and 2 demonstrated a "3." No animals in other groups (FOAM and control) demonstrated adhesions. CounterFlow-treated animals showed a statistically significant rise in d-dimer values in the 24-hour cohort only. In the 2-week cohort, CounterFlow-treated animals showed a decrease in body weight at 24 hours after injection but returned to their baseline (normal) body weights at 7 days. CONCLUSIONS: Findings from this study demonstrate that the tested ingredients of FOAM poloxamer component are safe for intraperitoneal injection and hold potential for further study directed toward prehospital non-compressible intra-abdominal hemorrhage management by non-surgical providers. Although CounterFlow produced abdominal adhesions in 3 of 4 rabbits in the 2-week cohort, these were determined to be "minimal" or "mild" in degree.

In vivo evaluation of venular glycocalyx during hemorrhagic shock in rats using intravital microscopy.

Hemorrhage is responsible for a large percentage of trauma-related deaths but the mechanisms underlying tissue ischemia are complex and not well understood. Despite the evidence linking glycocalyx degradation and hemorrhagic shock, there is no direct data obtained in vivo showing glycocalyx thickness reduction in skeletal muscle venules after hemorrhage. We hypothesize that damage to the endothelial glycocalyx is a key element in hemorrhage pathophysiology and tested the hypothesis that hemorrhage causes glycocalyx degradation in cremaster muscle microvessels. We utilized intravital microscopy to estimate glycocalyx thickness in 48 microvessels while other microvascular parameters were measured using non-invasive techniques. Systemic physiological parameters and blood chemistry were simultaneously collected. We studied 27 post-capillary venules (<16 µm diameter) of 8 anesthetized rats subjected to hemorrhage (40% of total blood volume). Six control rats were equally instrumented but not bled. Dextrans of different molecular weights labeled with FITC or Texas Red were injected. Glycocalyx thickness was estimated from the widths of the fluorescence columns and from anatomical diameter. While control rats did not show remarkable responses, a statistically significant decrease of about 59% in glycocalyx thickness was measured in venules after hemorrhagic shock. Venular glycocalyx thickness and local blood flow changes were correlated: venules with the greatest flow reductions showed the largest decreases in glycocalyx. These changes may have a significant impact in shock pathophysiology. Intravital microscopy and integrated systems such as the one described here may be important tools to identify mechanisms by which resuscitation fluids may improve tissue recovery and outcome following hemorrhage.

In vivo microvascular mosaics show air embolism reduction after perfluorocarbon emulsion treatment.

Massive arteriolar gas embolism (AGE) has never been evaluated in vivo using intravital microscopy and previous perfluorocarbon (PFC) emulsions were only effective in AGE when administered before AGE. We implemented a new system for quantitative studies of massive AGE using brightfield microscopy and tested a treatment with a third-generation PFC emulsion after massive AGE. We studied bubble dynamics in cremaster muscles from anesthetized rats after AGE was induced by direct air injection into the femoral artery ipsilateral to the studied muscle. Using a motorized microscope stage and a color camera, in vivo microvascular mosaics were produced on-line from over 2000 digital images to evaluate multiple networks in order to investigate the distribution, lodging, breaking, reduction and moving of 105 air bubbles in microvessels. Thirty minutes after PFC treatment, there was a reduction of 80% in bubble volume while untreated and saline-treated rats showed significantly smaller decreases of 33% and 40%, respectively (p<0.05). Air bubbles also dissolved into a larger number of smaller bubbles after PFC treatment. The proposed methodology may prove useful for rapid in vivo data acquisition from large networks. Since large air bubbles broke-up, decreased in length and volume, and moved toward smaller microvessels, the study provides quantitative data to support a mechanism by which PFC may improve tissue blood flow following massive AGE. The findings suggest that this new generation of PFC emulsions administered after severe AGE may reach compromised microvascular networks and provide help to alleviate microvascular obstruction by increasing air bubble reabsorption.

Cellular and Biochemical Effects of Combined X-Ray Radiation and Storage on Whole Blood.

BACKGROUND: Evaluating the impact of ionizing radiation on stored blood is relevant since blood banks are major assets in emergency conditions such as radiation incident/attack. This study aimed to fill our knowledge gap of combined radiation and storage effects on blood. METHODS: Blood collected from 16 anesthetized rats was anticoagulated, aliquoted into storage bags, and assigned to 8 groups using protocols combining storage (1-day vs 3-day 4oC) plus irradiation (75 Gy vs 0 Gy - control). Bags were positioned inside an X-ray irradiator (MultiRad-350). Complete blood count, differential white blood cell count, biochemistry, and hemostasis were analyzed (≥7 bags/group). RESULTS: Na+, bicarbonate, glucose, and pH significantly reduced, while K+, Cl-, and lactate increased by storage. Coagulation measures were not significantly altered after radiation. White blood cell count and most cell types were numerically reduced after radiation, but changes were statistically significant only for monocytes. No significant alterations were noted in aggregation or rotational thromboelastometry parameters between irradiated and control. CONCLUSIONS: Evaluating cellular/biochemical parameters aids in assessing stored blood adequacy after radiation. Data suggest that fresh or cold-stored blood can sustain up to 75 Gy without major critical parameter changes and may remain suitable for use in critically ill patients in military/civilian settings.

Tissue oxygenation and microvascular hemodynamics in experimental arterial gas embolism.

Microvascular hemodynamic responses to arterial gas embolism (AGE) and local oxygen tensions (PO2) have never been evaluated in vivo using intravital microscopy. A system was implemented to study AGE in real time using brightfield and phosphorescence microscopy as well as laser-induced microvessel occlusion. Bubble dynamics, microhemodynamics and oxygenation were studied following AGE in 61 microvessels and 41 interstitial spaces from 19 anesthetized rats. AGE was induced by direct air injection into the femoral artery ipsilateral to the studied cremaster muscle. Bubble-induced vaso-occlusion was investigated, and microvascular blood flow redistribution were associated with changes in intravascular and interstitial PO2. Microvascular blood flow as well as intravascular and tissue PO2 decreased after microvascular occlusion following microembolism. However, certain areas did not become fully hypoxic since redistribution of blood allowed oxygen to be supplied by nearby microvessels with blood (or plasma) flow or tissue gas diffusion. A linear correlation between interstitial and intravascular PO2 was found during baseline and after AGE. Because some microvessels remain flowing even after AGE, our observations suggest that intravascular therapeutic agents administered during severe AGE may reach microvascular networks and provide additional oxygenation to tissue areas where blood flow is compromised due to occlusion of some microvessels.

Role of albumin on endothelial basement membrane and hemostasis in a rat model of hemorrhagic shock.

BACKGROUND: We sought to determine the extent of loss of endothelial basement membrane (BM), leukocyte recruitment, and changes in coagulation after hemorrhagic shock, followed by limited-volume resuscitation (LVR) with 5% albumin (ALB). METHODS: Anesthetized rats were bled 40% of blood volume and assigned to treatment groups: untreated (n = 6), LVR with normal saline (NS; n = 8), or LVR with ALB (n = 8). Sham rats (n = 6) underwent all procedures except hemorrhage or resuscitation. Blood samples were assayed for active proteases, such as metalloproteinase 9 (MMP-9) and a disintegrin and metalloproteinase 10 (ADAM-10), BM-type heparan sulfate proteoglycan (perlecan), cell count, and coagulation function. Leukocyte transmigration was used to estimate the net efficiency of leukocyte recruitment in cremaster venules. RESULTS: Hemorrhage significantly lowered red cell count, but white cell and platelet counts did not change (vs. sham). Ionized calcium in plasma was significantly reduced in untreated and remained so after NS. In contrast, ionized calcium was normalized after ALB. Plasma expansion after NS and ALB further reduced leukocyte and platelet counts. Metalloproteinase 9, ADAM-10, and perlecan were significantly higher in untreated rats (vs. sham). Albumin normalized MMP-9, ADAM-10, and perlecan levels, while NS further increased MMP-9, ADAM-10, and perlecan (vs. sham). Transmigrated leukocytes doubled in the untreated group and remained elevated after NS (vs. sham) but normalized after ALB. Albumin reduced every stage of the leukocyte recruitment process to sham levels. CONCLUSION: Despite similar plasma expansion, NS weakened platelet function contrary to ALB. Plasma expansion with ALB resulted in restoration of BM integrity and attenuation of leukocyte recruitment to tissues, in contrast to NS. Albumin plays a critical role in restoring BM integrity, attenuating leukocyte recruitment to tissues, and optimizing hemostasis by increasing ionized calcium in plasma.

Rhabdomyosarcoma in a yellow-headed caracara (Milvago chimachima).

Rhabdomyosarcoma is a malignant tumor originating from rhabdomyoblasts that is rarely reported in domestic animals or in free-living and pet birds. This paper presents a case of rhabdomyosarcoma in a free-ranging yellow-headed caracara (Milvago chimachima), originating from the muscle region of proximal left humerus, with metastases in the left pectoral muscles, heart, lungs, and proventriculus. The cytology was suggestive of rhabdomyosarcoma because of malignant features and cytoplasmic cross-striations in cells. The histopathologic examination revealed neoplastic proliferation composed of spindle cells arranged in irregular sheets or bundles with marked cellular pleomorphism, moderate mitotic ratio, and multinucleated giant cells. Some neoplastic cells also presented evidence of scant cytoplasmic cross-striations visible at histologic sections stained by hematoxylin and eosin and phosphotungstic acid hematoxylin. Immunohistochemically, tumors cells were positive for desmin and negative for alpha-smooth muscle actin and S100 protein.

Detection and Molecular Characterization of a Natural Coinfection of Marek's Disease Virus and Reticuloendotheliosis Virus in Brazilian Backyard Chicken Flock.

Marek's disease virus (MDV) and the reticuloendotheliosis virus (REV) are two of the primary oncogenic viruses that significantly affect chickens. In Brazil, there have been no previous published reports on the presence of field REV alone or in coinfection. This retrospective study analyzes samples from a case of lymphoproliferative lesions from a backyard chicken flock. MDV and REV were detected by PCR and classified as MDV1 and REV3, respectively, through sequencing and phylogenetic analysis based on the glycoprotein B (gB) genes for MDV and the polymerase (pol) and envelope (env) genes for REV. Real-time PCR reactions were performed for MDV to rule out the presence of the Rispens vaccine strain. This is the first report of the presence of REV in coinfection with a MDV clinical case in Brazil and the first molecular characterization of REV in South America. This study highlights the importance of molecular diagnosis for REV and MDV in poultry. In addition, this study highlights the distribution of these two viruses worldwide and the latent risk of them solely or in coinfection to this part of the world.

Novel Adjunct Drugs Reverse Endothelial Glycocalyx Damage After Hemorrhagic Shock in Rats.

INTRODUCTION: There is interest in the small-volume therapeutic use of adjunct drugs for treating hemorrhagic shock (HS). However, critical information is only partially available on mechanisms of action of promising compounds such as adenosine-lidocaine-magnesium (ALM), beta-hydroxybutyrate plus melatonin (BHB/M), and poloxamer 188 (P-188). Therefore, we tested the hypothesis that these adjuncts would reverse HS-induced damage to microvascular endothelial glycocalyx and hemodynamics. METHODS: After baseline, 40% of total blood volume was removed from 44 anesthetized Sprague-Dawley male rats. One hour after hemorrhage, animals were resuscitated using ALM, BHB/M, or P-188 followed by lactated Ringer's (LR, 15 mL/kg). Control animals were not treated (SHAM) or received LR alone. Sampled blood was used to quantify shed syndecan-1 in plasma; multiple systemic physiological parameters were recorded. In vivo glycocalyx thickness, microvascular permeability, and microhemodynamics were evaluated in >200 cremaster venules using intravital videomicroscopy. RESULTS: Compared with baseline, resuscitation using adjuncts was associated with glycocalyx restoration of 97 ±â€Š9% (ALM), 75 ±â€Š8% (BHB/M), and 85 ±â€Š5% (P-188): significantly higher than LR-only (56 ±â€Š4%). Significantly better permeability, similar to SHAM values, was measured after ALM and P-188, and low plasma syndecan-1 levels were measured after resuscitation with all adjuncts. Microhemodynamic changes were relatively small while systemic parameters such as mean arterial pressure and lactate improved but remained below or above the baseline, respectively, as expected from this hypotensive resuscitation model. CONCLUSION: The drugs ALM, BHB/M, and P-188 provide beneficial effects as adjuncts to hypotensive resuscitation in this HS model by mechanisms involving changes at the microvascular level including the glycocalyx.

Tomography, Radiography, and Rhinoscopy in Diagnosis of Benign and Malignant Lesions Affecting the Nasal Cavity and Paranasal Sinuses in Dogs: Comparative Study.

Canine nasal and paranasal diseases have variable causes. Presumptive diagnosis is based on clinical manifestations; however, high similarity of clinical signs often calls for diagnostic imaging modalities and rhinoscopy before a definitive diagnosis can be reached. This study sets out to determine the value of rhinoscopy, radiography, and computed tomography (CT) of the head for canine nasal and paranasal disease diagnosis using a purposely developed comparative score. In all, 20 dogs presenting with clinical signs consistent with nasal disease were used. Patients were submitted to radiographic, CT, and rhinoscopic assessment; rhinoscopy-guided biopsy collection was performed in cases presenting with tissue proliferation, ulceration, or other nasal mucosal lesions. Rhinoscopy and rhinoscopy combined with CT significantly contributed to nasal disease diagnosis. Rhinoscopy and CT are complementary diagnostic modalities. Rhinoscopy proved helpful for confirmation of presumptive diagnosis and allowed image-assisted biopsy collection whereas CT contributed to effective determination of lesion extension and involvement of adjacent structures. Yet, histologic confirmation remains vital for definitive diagnosis.

Pneumonia and bacteremia in a golden-headed lion tamarin (Leontopithecus chrysomelas) caused by Klebsiella pneumoniae subsp. pneumoniae during a translocation program of free-ranging animals in Brazil.

Klebsiella pneumoniae is an important emerging pathogen in humans, particularly the invasive hypermucoviscosity (HMV) phenotype. In addition, the organism is an important public health concern because of nosocomial infections and antimicrobial resistance. Nonhuman primates in captivity are susceptible to Klebsiella, particularly when a stress factor is involved. Infections vary depending on the species but can cause significant morbidity and mortality in these animals. The objective of this study was to describe a case of bronchopneumonia and bacteremia caused by Klebsiella pneumoniae in a free-ranging golden-headed lion tamarin (Leontopithecus chrysomelas) caught and maintained in quarantine during a translocation program for conservation purposes. An adult male, that had showed emaciation and apathy, was clinically examined and, despite being provided supportive therapy, died 2 days after onset of clinical signs. At postmortem examination, generalized bilateral pneumonia and pericarditis were observed. Tissue samples were fixed in 10% formalin for histology, and pulmonary tissues and cardiac blood were collected for microbiologic diagnostic procedures. Bacteria that were shown to be HMV K. pneumoniae subsp. pneumoniae strains were isolated from the pulmonary fluids and cardiac blood in pure cultures. Severe bronchopneumonia was the main pathological finding. The consequences of the confirmed presence of the HMV phenotype of K. pneumoniae subsp. pneumoniae in this wildlife species for human, animal, and ecosystem health should be determined. These results demonstrate the importance of quarantine and potential pathogen screening during wildlife translocation procedures.

Systemic and microvascular effects of resuscitation with blood products after severe hemorrhage in rats.

BACKGROUND: Severe hemorrhage is associated with the disruption of the endothelial glycocalyx (EG), a key component of the endothelium. The effects of blood components on the EG are unknown. The present study furthers our investigations into the effects of resuscitation with blood products on the skeletal muscle microcirculation of hemorrhaged rats, focusing on packed red blood cells (PRBCs) or fresh whole blood (FWB). METHODS: Rats were bled 40% of total blood volume and resuscitated with 1:1 PRBC/lactated Ringer's solution (LR), 1:1 washed PRBC (wPRBC)/LR, FWB or LR only. Sham animals were subjected to all procedures except hemorrhage and resuscitation. EG thickness, blood flow, and microvascular permeability were studied using intravital microscopy. Hemodynamics and coagulation tests (rotational thromboelastometry) were performed. RESULTS: After severe hemorrhage, EG and permeability were restored to sham levels in the PRBC/LR and FWB groups, but not in the wPRBC/LR or LR groups. Clotting time was longer and clot elasticity and firmness were reduced in wPRBC/LR and LR, but not in FWB or PRBC/LR groups when compared with sham. CONCLUSION: Resuscitation with FWB or PRBC/LR was superior in reversing coagulopathy, restoring EG and permeability changes following hemorrhage, compared with wPRBC/LR or LR alone. As wPRBC/LR did not improve EG and permeability, these data suggest that the removal of residual plasma protein from wPRBC or resuscitation with a protein-free solution (LR) is not able to improve microcirculation and coagulation functions in this severe hemorrhage model.

Evaluation of resuscitation fluids on endothelial glycocalyx, venular blood flow, and coagulation function after hemorrhagic shock in rats.

BACKGROUND: Endothelial glycocalyx (EG) plays an essential role in endothelium integrity and may be compromised by hemorrhagic shock. The effects of currently available resuscitation fluids such as Hextend (HEX) or lactated Ringer's solution (LR) on vascular function and coagulation are not well understood. The aim of the present study was to compare the effects of fresh frozen plasma (FFP) with HEX or LR in their ability to repair EG structure, promote volume expansion, increase blood flow, and prevent coagulopathy. METHODS: A total of 121 microvessels from cremaster muscle were studied in 32 anesthetized instrumented rats. After baseline systemic and microvascular measurements, 40% hemorrhage followed by resuscitation was performed, and measurements were repeated. Coagulation was evaluated using ROTEM to assay clot formation time, clotting time, firmness, strength, and lysis. Velocity and "platelet component" of strength were calculated. Fluorescein isothiocyanate or Texas Red bound to Dextrans was injected to estimate EG thickness in vivo. RESULTS: Respiratory rate, blood pH, base excess, and lactate returned to near-baseline levels in all treatments. Hemodilution caused by LR and HEX decreased firmness, prolonged clotting time, and lowered platelet counts. EG thickness in HEX- and LR-treated rats was 50% lower, and plasma syndecan 1 was 50% higher than sham and FFP groups. Blood flow and shear rate were restored in the HEX group. Resuscitation with FFP improved coagulation and blood flow. CONCLUSION: Our findings support the concept of cardiovascular and microvascular stabilization by infused FFP, in which the increase in microvascular perfusion associated with restored EG is essential for an optimal resuscitation strategy.

Early physiologic responses to hemorrhagic hypotension.

The identification of early indicators of hemorrhagic hypotension (HH) severity may support early therapeutic approaches and bring insights into possible mechanistic implications. However, few systematic investigations of physiologic variables during early stages of hemorrhage are available. We hypothesized that, in certain subjects, early physiologic responses to blood loss are associated with the ability to survive hemorrhage levels that are lethal to subjects that do not present the same responses. Therefore, we examine the relevance of specific systemic changes during and after the bleeding phase of HH. Stepwise hemorrhage, representing prehospital situations, was performed in 44 rats, and measurements were made after each step. Heart and respiratory rates, arterial and venous blood pressures, gases, acid-base status, glucose, lactate, electrolytes, hemoglobin, O(2) saturation, tidal volume, and minute volume were measured before, during, and after bleeding 40% of the total blood volume. Fifty percent of rats survived 100 min (survivors, S) or longer; others were considered nonsurvivors (NS). Our findings were as follows: (1) S and NS subjected to a similar hemorrhage challenge showed significantly different responses during nonlethal levels of bleeding; (2) survivors showed higher blood pressure and ventilation than NS; (3) although pH was lower in NS at later stages, changes in bicarbonate and base excess occurred already during the hemorrhage phase and were higher in NS; and (4) plasma K(+) levels and glucose extraction were higher in NS. We conclude that cardiorespiratory and metabolic responses, essential for the survival at HH, can differentiate between S and NS even before a lethal bleeding was reached.

Microvascular blood flow and oxygenation during hemorrhagic hypotension.

Understanding microvascular oxygen transport requires the knowledge of microvessel topology and geometry, blood flow and oxygen levels. Microvascular hemodynamic responses to hemorrhagic hypotension (HH) such as size-dependent vasoconstriction and blood flow reduction could lead to increased longitudinal oxygen partial pressure (PO(2)) gradients. However, the mesenteric microvascular PO(2) has never been evaluated during HH. Therefore, we studied hemodynamic variables and PO(2) distribution in 165 mesenteric microvessels from 39 anesthetized rats to investigate whether HH-induced vasoconstriction and blood flow reduction were associated with changes in longitudinal PO(2) gradients. Vessels were analyzed according to their position in the network, as well as a few interstitial PO(2) areas. We found that during baseline a small PO(2) gradient exists, but HH is accompanied by more pronounced microvascular longitudinal PO(2) gradients. Decreased blood flow did not seem to completely explain these findings, since blood flow was uniformly diminished in arterioles and venules, independent of diameter and position in the network. During HH, some microvessels presented higher PO(2) than during baseline despite blood flow reduction, possibly due to a combination of systemic hyperoxia and low oxygen consumption of mesentery. The data suggest that blood flow measurements may be a poor indicator of the oxygenation status in some regions of the mesentery. The enhanced mesenteric longitudinal PO(2) gradient may lead to regions with different levels of other physiologically active compounds.

Avaliação ultrassonográfica de linfonodos na pesquisa de metástases de neoplasia mamária em cadelas / Ultrasonographic evaluation of lymph nodes for metastasis research of canine mammary tumor

A avaliação de linfonodo, parte importante do estadiamento das neoplasias mamárias em cadelas, pode auxiliar no estabelecimento do prognóstico e na escolha da conduta terapêutica. A ultrassonografia em modo B possibilita avaliação de tamanho, contorno, borda, forma, arquitetura, ecotextura e ecogenicidade do parênquima dos linfonodos e, em modo Doppler, da quantidade e distribuição dos seus vasos internos. Este trabalho visou identificar as características ultrassonográficas mais importantes utilizadas para classificar os linfonodos em metastáticos e não-metastáticos, estabelecer elementos de confiabilidade do ultrassom como ferramenta para diferenciar linfonodos metastáticos de não-metastáticos e estabelecer procedimentos de reprodução deste exame. Foram examinados 67 linfonodos inguinais superficiais de 30 cadelas com tumor mamário e cada linfonodo foi classificado como metastático ou não-metastático. A impressão diagnóstica ultrassonográfica foi associada aos resultados do exame histopato lógico dos linfonodos obtendo-se taxa de concordância de 92,5 por cento, índice de sensibilidade de 94,1 por cento, índice de especificidade de 92 por cento, valor preditivo positivo de 0,8 e valor preditivo negativo de 0,9787. Características ultrassonográficas que classificaram um linfonodo como metastático ou como não-metastático foram listadas. O exame ultrassonográfico dos linfonodos regionais constitui importante ferramenta na detecção de metástase e sugere-se incluí-lo como rotina do estadiamento de neoplasias mamárias em cadelas.

Evaluation of lymph nodes is part of the staging of the mammary tumors and helps to establish a prognosis and therapy. B-mode ultrasonography was used to evaluate size, edge, nodal borders, shape, architecture, echotexture and echogenicity of lymph nodes and Doppler ultrasonography to evaluate the quantity and distribution of the vessels. The aims of this work were to identify which ultrasound features can be used to classify a lymph node as metastatic or non-metastatic; to establish its accuracy as a useful tool to this differentiation, and to establish procedures that permit the reproducibility of the results. Sixty seven lymph nodes of 30 female dogs with mammary tumors were examined by ultrasound and classified as metastatic or non-metastatic. The ultrasonographic diagnostic impression was confronted with the histopathologic results. The ultrasonographic classification of the lymph nodes was correct in 92.5 percent of the cases, with sensibility of 94.1 percent, specificity of 92 percent, positive predictive value of 0.8, and negative predictive value of 0.9787.The characteristics of the nodes to classify them as metastatic or non metastatic were registered. Ultrasound imaging of regional lymph nodes is important to detect metastases and it is suggested that it becomes a regular procedure in the staging of canine mammary tumors.