Lymphatic Flux Research Articles

Abstract 3056: IL-19 Is A VEGFC-inducible Lymphokine That Regulates Prox1 Through RNA Stability

Introduction: During inflammatory diseases, such as atherosclerosis, malfunctional lymphangiogenesis occurs. Studies suggest that inflammation induces a zipper morphology in lymphatic junctions which limits lymphatic function, but this phenomenon has never been evaluated under atherogenic conditions. We previously reported that IL-19 is anti-inflammatory, anti-atherosclerotic, and pro-angiogenic. The purpose of this study is to test the hypothesis that IL-19 induces functional lymphangiogenesis under atherosclerotic conditions. Methods & Results: Both IL-19 and VEGFC, a vital pro-lymphangiogenic factor, induce IL-19 protein expression in lymphatic endothelial cells (LECs). Interestingly, IL-19 does not induce VEGFC protein expression. IL-19 treatment does induce expression of Prox1, the master regulator of lymphatic development. Proliferation, migration, and tube formation assays confirmed IL-19 induces lymphangiogenesis. IL-19 also promotes short- and long-term regulation of lymphatic permeability by rapidly inducing VE-cadherin phosphorylation and slowly increasing Angpt2 expression. In the presence of oxLDL, LECs have decreased permeability via electric cell-substrate impedance sensing and increased zippers via immunocytochemistry, while co-treatment with IL-19 maintains LEC barrier function. Ldlr -/- Il19 -/- double knockout (dKO) mice, known to have exacerbated atherosclerosis, have significantly worse lymphatic function compared to Ldlr -/- on a high fat diet. However, dKO and Ldlr -/- mice on chow diet have similar lymphatic function, again suggesting a role for IL-19 by maintaining lymphatic flux under pro-inflammatory conditions. Although IL-19 canonically phosphorylates STAT3 in LECs, STAT3 knockdown does not affect Prox1 expression. However, Prox1 knockdown prevents IL-19-associated lymphangiogenesis and Angpt2 upregulation. Since IL-19 is known to alter mRNA stability, we performed Actinomycin D assays and determined IL-19 increases Prox1 mRNA stability, possibly contributing to Prox1 upregulation independent of STAT3 activity. Conclusion: IL-19 is a previously un-recognized regulator of lymphangiogenesis and could potentially promote lymphatic function during inflammation.

Abstract 13070: Interleukin-19 Regulates Lymphatic Permeability and Induces Prox1-Dependent Lymphangiogenesis

Introduction: Increased lymphangiogenesis is associated with atherosclerosis, but whether it is disease-causative or a compensatory attempt to attenuate disease is currently unresolved. Recent studies suggest lymphatic permeability plays a role in reverse cholesterol transport (RCT) as a possible mechanism for attenuating atherosclerosis. We previously reported that that Interleukin-19 (IL-19), an immunomodulatory cytokine, is unique by inducing angiogenesis while reducing atherosclerosis. The purpose of this study was to test the hypothesis that IL-19 could be atheroprotective by inducing functional lymphangiogenesis and promoting lymphatic flux. Methods & Results: RNA sequencing of IL-19-treated human Lymphatic Endothelial Cells (hLEC) identified induction of chemokines, pro-lymphangiogenic, and permeability-associated genes. Prox1, the master regulator of lymphatic formation, was increased by six-fold, validated by qPCR and western blot. Cellular assays further demonstrated IL-19-associated lymphangiogenesis through hLEC proliferation, migration, and tube formation, each mitigated by Prox1 siRNA knockdown. Angpt2, a regulator of permeability through VE-cadherin, is also upregulated by IL-19 and mitigated by Prox1 siRNA knockdown. Electric Cell-substrate Impedance Sensing (ECIS) showed that IL-19 mitigates oxLDL-associated decreases in permeability, suggestive of preventing lymphatic barrier malfunction during atherosclerosis. Preliminary in vivo lymphatic permeability assays suggest injection of rmIL-19 improves lymphatic function in conditional lymphatic-specific Prox1 heterozygous mice. Conversely, similar experiments show that Il19 / LDLR double knockout mice, which are known to have exacerbated atherosclerosis, also have significantly decreased lymphatic permeability compared to LDLR -/- mice after 16-weeks of high fat diet. Conclusion: These data suggest that IL-19 is a previously unrecognized regulator of lymphatic function as it increases lymphangiogenesis and permeability, with the potential to improve RCT. Together, these effects may regulate atherosclerosis, and influence our understanding of the association between the lymphatic system and atherosclerosis.

Abstract 712: IL-19 Is A Lymphokine That Induces Prox1-dependent Lymphangiogenesis And Permeability

Introduction: Atherosclerosis is a vascular inflammatory disease associated with lymphangiogenesis, but whether lymphangiogenesis contributes to disease progression or is simply a compensatory attempt at disease resolution is currently unresolved. Recent studies are revealing a role for lymphatic vessels in reverse cholesterol transport (RCT), which could attenuate atherosclerosis. We have previously reported that Interleukin-19 (IL-19), an anti-inflammatory cytokine, uniquely attenuates atherosclerotic plaque progression while also being pro-angiogenic. This drives our hypothesis that one mechanism whereby IL-19 is atheroprotective is by promoting functional lymphangiogenesis and lymphatic flux. Methods & Results: IL-19 can significantly induce human dermal lymphatic endothelial cell (hdLEC) proliferation, migration, and tube formation, to the same degree as VEGFC, a potent inducer of lymphangiogenesis. RNA sequencing analysis indicates that IL-19 induces an angiogenic transcriptional program through Prox1, a master regulator of lymphangiogenesis. Knockdown of Prox1 led to a significant decrease in IL-19-associated proliferation and migration. IL-19 also increased expression of Angpt2, an endothelial cell protein that induces permeability through regulation of tight junctions, through a Prox1-dependent mechanism. Electric Cell-substrate Impedance Sensing assays showed that IL-19 treatment increased hdLEC permeability and mitigated oxLDL-associated decreased permeability, suggestive of maintaining lymphatic barrier function during atherosclerosis. IL-19 treatment also increased dil-HDL transport across an hdLEC barrier. Preliminary in vivo data suggests injection of rmIL-19 in Il19 -/- mice increases lymphatic permeability and flux through increased lymphatic uptake of Evans blue dye. Conclusion: These data suggest that IL-19 increases lymphangiogenesis, permeability, and may increase RCT to plausibly decrease atherosclerosis. These results can influence our understanding of the association between the lymphatic system and atherosclerosis.

Differential regulation of lymphatic junctional morphology and the potential effects on cardiovascular diseases.

The lymphatic vasculature provides an essential route to drain fluid, macromolecules, and immune cells from the interstitium as lymph, returning it to the bloodstream where the thoracic duct meets the subclavian vein. To ensure functional lymphatic drainage, the lymphatic system contains a complex network of vessels which has differential regulation of unique cell-cell junctions. The lymphatic endothelial cells lining initial lymphatic vessels form permeable "button-like" junctions which allow substances to enter the vessel. Collecting lymphatic vessels form less permeable "zipper-like" junctions which retain lymph within the vessel and prevent leakage. Therefore, sections of the lymphatic bed are differentially permeable, regulated in part by its junctional morphology. In this review, we will discuss our current understanding of regulating lymphatic junctional morphology, highlighting how it relates to lymphatic permeability during development and disease. We will also discuss the effect of alterations in lymphatic permeability on efficient lymphatic flux in health and how it may affect cardiovascular diseases, with a focus on atherosclerosis.

An in silico approach to understanding the interaction between cardiovascular and pulmonary lymphatic dysfunction.

The lung is extremely sensitive to interstitial fluid balance, yet the role of pulmonary lymphatics in lung fluid homeostasis and its interaction with cardiovascular pressures is poorly understood. In health, there is a fine balance between fluid extravasated from the pulmonary capillaries into the interstitium and the return of fluid to the circulation via the lymphatic vessels. This balance is maintained by an extremely interdependent system governed by pressures in the fluids (air and blood) and tissue (interstitium), lung motion during breathing, and the permeability of the tissues. Chronic elevation in left atrial pressure (LAP) due to left heart disease increases the capillary blood pressure. The consequent fluid accumulation in the delicate lung tissue increases its weight, decreases its compliance, and impairs gas exchange. This interdependent system is difficult, if not impossible, to study experimentally. Computational modeling provides a unique perspective to analyze fluid movement in the cardiopulmonary vasculature in health and disease. We have developed an initial in silico model of pulmonary lymphatic function using an anatomically structured model to represent ventilation and perfusion and underlying biophysical laws governing fluid transfer at the interstitium. This novel model was tested against increased LAP and noncardiogenic effects (increased permeability). The model returned physiologically reasonable values for all applications, predicting pulmonary edema when LAP reached 25 mmHg and with increased permeability.NEW & NOTEWORTHY This model presents a novel approach to understanding the interaction between cardiac dysfunction and pulmonary lymphatic function, using anatomically structured models and biophysical equations to estimate regional variation in fluid transport from blood to interstitial and lymphatic flux. This fluid transport model brings together advanced models of ventilation, perfusion, and lung mechanics to produce a detailed model of fluid transport in health and various altered pathological conditions.

Osteopathic lymphatic techniques reduces cortisol plasma level in rats after repeated treatments

BackgroundMany reports evidence in humans the positive effect of manipulation, in particular of osteopathic lymphatic techniques in normal as well in pathological conditions. In animals too, lymphatic treatment has been reported to induce changes of lymphatic flux and to mobilize inflammatory mediators thus determining positive effects on the immune system. MethodsTwelve male Wistar rats (weight 180 g) were randomly allocated to control (6 rats) and experimental (6 rats) group. Experimental group rats underwent lymphatic techniques for 10 min each day for 5 consecutive days under gaseous anaesthesia. Control group animals were anaesthetized but did not have lymphatic treatment. Blood samples were collected before and at the end of the experiment period. A complete blood cell count and serum chemistry were determined. TNF-alpha and IL-1 beta were determined in order to evaluate changes in inflammatory response. Cortisol was also determined as indicative of animal stress. The experiment was carried on in August 2011 and was replicated in February 2012. ResultsBlood cell count did not show differences at baseline and at the end of the experiment both in control and in treated rats. Blood serum chemistry was also unchanged. In particular, blood urea nitrogen (BUN) and serum creatinine (expression of renal function), alanine transaminase (ALT) and aspartate transaminase (AST) (indicative of hepatic cell integrity) were normal and did not change after lymphatic treatment. No changes in plasmatic level of cytokines were found after the five-days lymphatic treatment. On the contrary and unexpectedly, cortisol level was significantly reduced in rats that were treated with lymphatic techniques. In untreated rat group cortisol level was, however, minimally increased. These findings were confirmed by the results of the replicated study. ConclusionsThis study demonstrates that repeated lymphatic treatment is a safe procedure. Moreover, lymphatic techniques induce reduction in cortisol level, which may be related to an anti-stress effect.

Lymphatic pump manipulation mobilizes inflammatory mediators into lymphatic circulation

Lymph stasis can result in edema and the accumulation of particulate matter, exudates, toxins and bacteria in tissue interstitial fluid, leading to inflammation, impaired immune cell trafficking, tissue hypoxia, tissue fibrosis and a variety of diseases. Previously, we demonstrated that osteopathic lymphatic pump techniques (LPTs) significantly increased thoracic and intestinal duct lymph flow. The purpose of this study was to determine if LPT would mobilize inflammatory mediators into the lymphatic circulation. Under anesthesia, thoracic or intestinal lymph of dogs was collected at resting (pre-LPT), during four minutes of LPT, and for 10 min following LPT (post-LPT), and the lymphatic concentrations of interleukin-2 (IL-2), IL-4, IL-6, IL-10, interferon-γ, tissue necrosis factor α, monocyte chemotactic protein-1 (MCP-1), keratinocyte chemoattractant, superoxide dismutase (SOD) and nitrotyrosine (NT) were measured. LPT significantly increased MCP-1 concentrations in thoracic duct lymph. Further, LPT increased both thoracic and intestinal duct lymph flux of cytokines and chemokines as compared with their respective pre-LPT flux. In addition, LPT increased lymphatic flux of SOD and NT. Ten minutes following cessation of LPT, thoracic and intestinal lymph flux of cytokines, chemokines, NT and SOD were similar to pre-LPT, demonstrating that their flux was transient and a response to LPT. This re-distribution of inflammatory mediators during LPT may provide scientific rationale for the clinical use of LPT to enhance immunity and treat infection.

Lymphatic Pump Treatment Augments Lymphatic Flux of Lymphocytes in Rats

Lymphatic pump techniques (LPT) are used by osteopathic practitioners for the treatment of edema and infection; however, the mechanisms by which LPT enhances the lymphatic and immune systems are poorly understood. To measure the effect of LPT on the rat, the cisterna chyli (CC) of 10 rats were cannulated and lymph was collected during 4 min of 1) pre-LPT baseline, 2) 4 min LPT, and 3) 10 min post-LPT recovery. LPT increased significantly (p < 0.05) lymph flow from a baseline of 24 ± 5 μl/min to 89 ± 30 μl/min. The baseline CC lymphocyte flux was 0.65 ± 0.21 × 10⁶ lymphocytes/min, and LPT increased CC lymphocyte flux to 6.10 ± 0.99 × 10⁶ lymphocytes/min (p < 0.01). LPT had no preferential effect on any lymphocyte population, since total lymphocytes, CD4+ T cells, CD8+ T cells, and B cell numbers were similarly increased. To determine if LPT mobilized gut-associated lymphocytes into the CC lymph, gut-associated lymphocytes in the CC lymph were identified by staining CC lymphocytes for the gut homing receptor integrin α4β7. LPT significantly increased (p < 0.01) the flux of α4β7 positive CC lymphocytes from a baseline of 0.70 ± 0.03 × 10⁵ lymphocytes/min to 6.50 ± 0.10 × 10⁵ lymphocytes/min during LPT. Finally, lymphocyte flux during recovery was similar to baseline, indicating the effects of LPT are transient. Collectively, these results suggest that LPT may enhance immune surveillance by increasing the numbers of lymphocytes released in to lymphatic circulation, especially from the gut associated lymphoid tissue. The rat provides a useful model to further investigate the effect of LPT on the lymphatic and immune systems.

1088 Serum levels of vascular endothelial growth factor receptor 2 (VEGFR2): prognostic biomarker in advanced non-small cell lung cancer (NSCLC)?

The sentinel lymph node (SLN) concept is that lymphatic flux from a primary tumor initially flows into a SLN. The mechanism mediating tumor metastasis within SLNs remains largely unknown; however, primary tumors overexpressing vascular endothelial growth factor (VEGF)-A appear to induce SLN lymphangiogenesis prior to metastasis in animal model. Our aim was to further investigate the capacity of VEGFs to induce lymphangiogenesis within SLNs and to assess their role in SLN metastasis in non-small cell lung carcinoma (NSCLC).Real-time quantitative RT-PCR was used to assess expression of mRNAs encoding several VEGFs (VEGF121, VEGF165, VEGFR1, VEGFR2, VEGFR3, VEGF-C and VEGF-D) in resected lymph node specimens from 35 NSCLC patients, after which we compared their expression SLNs and non-SLNs. In addition, expression of the lymphatic endothelium-specific hyaluronan receptor (LYVE)-1 was used to assess lymphangiogenesis in SLNs and non-SLNs.Immunohistochemical staining revealed substantial expression of LYVE-1 in SLNs. Moreover, levels LYVE-1 mRNA were significantly higher in SLNs than non-SLNs (P < 0.05), as were levels of VEGF121 and VEGFR2 mRNA (P < 0.01 and P = 0.02, respectively). In addition metastasis-positive SLNs showed significantly higher levels of VEGF121, VEGF-C and VEGF-D mRNA than metastasis-negative SLNs (P < 0.001, P = 0.01 and P = 0.01, respectively), and VEGF121 induced the proliferation of lymphatic endothelial cells (P < 0.01).Our findings suggest that active lymphangiogenesis is ongoing within SLNs from NSCLC patients, even before metastasis. This lymphangiogenesis may be promoted by upregulation of VEGF121, which may in turn act in part via induction of VEGF-C.

VEGF121 promotes lymphangiogenesis in the sentinel lymph nodes of non-small cell lung carcinoma patients

The sentinel lymph node (SLN) concept is that lymphatic flux from a primary tumor initially flows into a SLN. The mechanism mediating tumor metastasis within SLNs remains largely unknown; however, primary tumors overexpressing vascular endothelial growth factor (VEGF)-A appear to induce SLN lymphangiogenesis prior to metastasis in animal model. Our aim was to further investigate the capacity of VEGFs to induce lymphangiogenesis within SLNs and to assess their role in SLN metastasis in non-small cell lung carcinoma (NSCLC). Real-time quantitative RT-PCR was used to assess expression of mRNAs encoding several VEGFs (VEGF121, VEGF165, VEGFR1, VEGFR2, VEGFR3, VEGF-C and VEGF-D) in resected lymph node specimens from 35 NSCLC patients, after which we compared their expression SLNs and non-SLNs. In addition, expression of the lymphatic endothelium-specific hyaluronan receptor (LYVE)-1 was used to assess lymphangiogenesis in SLNs and non-SLNs. Immunohistochemical staining revealed substantial expression of LYVE-1 in SLNs. Moreover, levels LYVE-1 mRNA were significantly higher in SLNs than non-SLNs (P<0.05), as were levels of VEGF121 and VEGFR2 mRNA (P<0.01 and P=0.02, respectively). In addition metastasis-positive SLNs showed significantly higher levels of VEGF121, VEGF-C and VEGF-D mRNA than metastasis-negative SLNs (P<0.001, P=0.01 and P=0.01, respectively), and VEGF121 induced the proliferation of lymphatic endothelial cells (P<0.01). Our findings suggest that active lymphangiogenesis is ongoing within SLNs from NSCLC patients, even before metastasis. This lymphangiogenesis may be promoted by upregulation of VEGF121, which may in turn act in part via induction of VEGF-C.

Preoperative mapping of lymphatic drainage from the tumor using ferumoxide-enhanced magnetic resonance imaging in clinical submucosal thoracic squamous cell esophageal cancer

In thoracic esophageal cancer, lymph node metastases distribute widely from the neck to the abdominal area as a result of a complex periesophageal lymphatic network. The aim of the present study was to evaluate the potential clinical utility of a new method of mapping lymphatic drainage from tumors using ferumoxide-enhanced magnetic resonance imaging (MRI). Twenty-three patients with clinical submucosal thoracic squamous cell esophageal cancer were examined. Ferumoxides were injected endoscopically into the peritumoral submucosal layer, after which their appearance in the lymph nodes in the neck, superior mediastinum, and abdomen was evaluated using MRI. Flux of ferumoxides from tumors was detected in all 23 patients. Among the 20 patients with middle and lower thoracic esophageal cancers, there was no lymphatic drainage to the neck in 5 (25%) patients, none to the neck and superior mediastinum in 4 (20%), and none to the abdomen in 2 (10%), which could enable the extent of lymph node dissection to be reduced. We diagnosed clinical negative lymph node metastasis (N0) in 17 patients; the remaining 6 patients were diagnosed with clinical lymph node metastasis. Two patients (12%) diagnosed clinical N0, showed pathologic lymph node metastasis. Ferumoxide-enhanced MRI detected an influx of contrast agent into the metastatic node in both patients. Ferumoxide-enhanced MRI lymphatic mapping enables detection of the direction and area of lymphatic flux. It thus has the potential to improve our ability to gauge the appropriate extent of treatment in clinical submucosal squamous cell esophageal cancer.

Abdominal pump treatment increases leukocyte count and flux in thoracic duct lymph

Previous studies suggest that rhythmic compression of the abdomen (abdominal lymphatic pump, ALP) enhances immunity and resistance to infectious disease, but direct evidence of this has not been documented. Thus, the hypothesis that ALP increases leukocyte numbers in thoracic duct lymph was tested in five anesthetized, open-chest dogs. The lymph duct was catheterized, lymph flow was measured, and lymph was collected under 1) baseline conditions, 2) during ALP. ALP increased lymph flow from 0.5±0.1 to 2.7±0.3 ml/min and increased leukocytes from 1.7±0.2 × 106 to 6.2±0.4 × 106cells/ml. Relative proportions macrophages, neutrophils, total lymphocytes, T cells, and B cells did not change during ALP. Considering increases in flow and leukocyte counts, ALP enhanced leukocyte flux from 0.75±0.04 × 106to 17 ± 2 × 106cells/min. In summary, ALP significantly increased both thoracic duct lymph flow and leukocyte count, so leukocyte lymphatic flux was markedly enhanced. Enhanced mobilization and lymphatic transport of immune cells during abdominal compression is likely an important mechanism responsible for the enhanced immune responses of patients treated with ALP. (Support: NIH grant U19 AT002023)

Blood-to-tissue clearance vs. lymph analysis in determining capillary transport characteristics for albumin in skin

The blood-to-tissue clearance of radioactive albumin and a lymphatic flux analysis were used to evaluate the transport properties of albumin in the canine hindpaw. A prenodal lymphatic was cannulated, and lymph was collected for a 2-h control period. Thereafter venous pressure was elevated between 7 and 31 mmHg. After 2 h of increased venous pressure, the radioactive tracer was given intravenously. During the next 2 h lymph was sampled, and at the end of this time tissue and blood samples were obtained. The experiments showed that, of the tracer filtered in excess of control at increased venous pressure, an estimated 21% was cleared via the lymphatics and 79% was retained in the tissue. As a percentage of total tracer flux at increased venous pressure, 9% (measured) was drained by lymph and 91% was retained in the tissue. Of the fluid filtered in excess of control at increased capillary pressure, 70% (measured) was drained via the lymphatics and 30% was retained in the tissue in the same period. Twice the amount of endogenous albumin filtered across the capillary wall was drained via the lymphatics during the experimental period. The lymphatic washout of endogenous albumin from the interstitium will cause an underestimation of the capillary reflection coefficient and overestimation of the permeability-surface area product. Because of the loss of tracer from the tissue, the opposite occurs when the blood-to-tissue clearance of radioactive albumin is used.

Increased lymphatic flux of hyaluronan from cat intestine during fat absorption.

During fat absorption, chylomicrons with sizes up to 5,000-10,000 A must traverse an interstitium that has estimated pore sizes of 120-200 A to reach the lacteals. The present experiments were performed to study the behavior of the interstitial matrix component hyaluronan during fat absorption from the intestine. Ileal segments were isolated and autoperfused in pentobarbital-anesthetized cats. A postnodal lymphatic was cannulated, and lymph flow, protein, and hyaluronan concentration in lymph were determined. In group 1, a mixture of oleic acid and taurocholate was infused into the ileal lumen, while in group 2 the animals were fed cream overnight. In group 1, control lymph flow and hyaluronan concentration averaged 53.3 +/- 16.0 (SD) microliters.min-1.100 g intestine-1 and 21.4 +/- 16.0 micrograms/ml, respectively. Administration of taurocholate and oleic acid increased lymph flow and lymph hyaluronan concentration by 100 and 50%, respectively, resulting in a nearly three-fold increase in hyaluronan flux. Subsequent increases in venous pressure increased lymph flow and reduced hyaluronan concentration in lymph to less than 3 micrograms/ml. Hyaluronan flux remained approximately 2 micrograms.min-1.100 g intestine-1 independent of lymph flow. In group 2, no lymph sample was available before administration of fat. Hyaluronan concentration at control venous pressure was 19.3 +/- 6.7 micrograms/ml and fell to 10 micrograms/ml at the highest lymph flow. Hyaluronan flux was approximately 10 micrograms.min-1.100 g intestine-1 at the highest lymph flow and venous pressure (P less than 0.05 compared with the same lymph flow in group 1).(ABSTRACT TRUNCATED AT 250 WORDS)

Marked increase of plasma hyaluronan after major thermal injury and infusion therapy

Hyaluronan (HYA) is an important structural element in skin and is presumably participating in regulation of the interstitial fluid volume. HYA is transported via the lymphatics from the tissues to the blood, where its concentration is normally very low. Fluid flux through the interstitium is markedly increased after thermal injury. The present study was performed to determine whether major thermal injury would affect plasma levels of HYA. In halothane-anesthetized sheep subjected to 40% BSA full-thickness scald burns, plasma HYA concentration increased from 116 ± 19 (mean ± SEM) to 172 ± 18 ng/ml within 1 hr after injury ( P < 0.05). After 3 hr of fluid therapy plasma HYA concentration was further elevated to 10 times baseline (1417 ± 322 ng/ml) ( P < 0.01). To clarify whether this rise represented an increased “washout” of interstitial HYA, attributable either to the burn injury or the subsequent fluid therapy, awake sheep were subjected to overhydration. Following a 3-hr infusion of lactated Ringer's 2.5 liter/hr, plasma HYA concentration increased to 2–3 times baseline. Lung lymph flow and its concentration of HYA increased, leading to an increase in the lymphatic flux of HYA to 10–20 times baseline. In peripheral lymph HYA flux increased 2–3 times baseline. Infusion of lactated Ringer's markedly increased lymphatic removal of HYA. However, plasma concentrations of HYA were 3 times higher after thermal injury than following fluid challenge alone, suggesting that thermal injury per se may also increase input of HYA into the systemic circulation.

Axillary lymphoscintigraphy: Current status in the treatment of breast cancer

Postoperative axillary lymphoscintigraphy has been performed after time-differentiated intercostal and interdigital injections of a 99Tc-labeled sulfur microcolloid in 313 patients suffering from breast cancer who underwent radical surgery with axillary dissection. As demonstrated by the absence of visualized lymph nodes after both injections, the axillary dissection could be considered as complete in only 34.6% of the investigated patients. The greatest part of lymph nodes, remaining after surgery, corresponds to the inferior and central groups (after interdigital injection). In 15% of the cases the intercostal injection leads to the demonstration of external mammary lymph nodes. According to the analysis of 202 cases with at least 1 year follow-up, the existence of visualized residual lymph nodes represents a factor of risk to develop nodal relapse especially in patients with positive peroperative axillary lymph node status who did not receive postoperative X-ray treatment. Upper limb edema occurs in 22.5% of the cases; mainly in patients with negative lymphoscintigraphic findings (demonstrating the interruption of the axillary lymphatic flux) and without nodal irradiation. Postoperative axillary lymphoscintigraphic findings should be evaluated in connection with the peroperative axillary lymph node status as established according to the histological analysis, and should take into account the number of removed lymph nodes. Preoperative axillary lymphoscintigraphy seems to be a less contributive examination technique.

Bradykinin Production and Increased Pulmonary Endothelial Permeability during Acute Respiratory Failure in Unanesthetized Sheep

To investigate mechanisms of pulmonary edema in respiratory failure, we studied unanesthetized sheep with vascular catheters, pleural balloons, and chronic lung lymph fistulas. Animals breathed either a hypercapnic-enriched oxygen (n = 5) or a hypercapnic-hypoxic (n = 5) gas mixture for 2 h. Every 15 min blood gases, pressures, cardiac output, lymph flow (Qlym), plasma and lymph albumin (mol wt, 70,000), IgG (mol wt, 150,000), IgM (mol wt, 900,000), and blood bradykinin concentrations were determined. In both groups, cardiac output and pulmonary arterial pressures increased, whereas left atrial pressures were unchanged. Acidosis alone (arterial pH = 7.16, PaCO(2) = 81 mm Hg, PaO(2) = 250 mm Hg) resulted in a doubling of lymph flow, a small increase in protein flux, and a decrease in lymph to plasma protein concentration (L/P) ratio for all three proteins. Acidotic-hypoxic animals (arterial pH = 7.16, PaCO(2) = 84 mm Hg, PaO(2) = 48 mm Hg) tripled Qlym. In these animals the increase in lymphatic flux of albumin, IgG, and IgM was significantly (P < 0.05) greater than that seen in either the acidosis alone group or in animals where left atrial pressures were elevated (n = 5; P < 0.05). Also, their percent increase in flux of the large protein (IgM) was greater than for the small protein (albumin) (P < 0.05). With acidosis alone, only pulmonary arterial bradykinin concentration increased (1.27+/-0.25 ng/ml SE), whereas acidosis plus hypoxia elevated both pulmonary arterial bradykinin concentrations (4.83+/-1.14 ng/ml) and aortic bradykinin concentration (2.74+/-0.78 ng/ml). These studies demonstrate that hypercapnic acidosis stimulates in vivo production of bradykinin. With superimposed hypoxia, and therefore decreased bradykinin degradation, there is an associated sustained rise in Qlym with increased lung permeability to proteins.