Lymphedema

Measurement of skin desmosine as an indicator of altered cutaneous elastin in draft horses with chronic progressive lymphedema

BACKGROUND

Chronic progressive lymphedema in Clydesdale and Shire draft horses causes severe disability of the limbs which leads to premature death of these horses. Since appropriate function of lymph vessels is dependent on the presence of viable elastin fibers, the goal of this study was to document differences in skin elastin fibers in affected horse breeds, compared to a nonaffected draft horse breed.

METHODS AND RESULTS

Biochemical analysis of cutaneous desmosine, a cross-linking amino acid found only in elastin, was used to measure elastin in the skin from 110 draft horses. This included 7 normal, 38 mildly affected, 30 moderately, and 15 severely affected horses, and 20 horses of a nonaffected draft breed. Desmosine concentrations in neck, considered a nonaffected skin region, and left forelimb, an affected skin region, were compared between the groups. A significantly lower desmosine concentration was found in the skin of the neck and limb of clinically normal animals of affected draft breeds compared to a nonaffected draft horse breed. During the progression of the disease in the affected breeds, cutaneous desmosine concentrations most prominently increased in the skin of the distal limbs.

CONCLUSIONS

Chronic progressive lymphedema in draft horses was associated with an initially systemic lower cutaneous elastin level and a deposition of elastin during the progression of the disease. A failure of elastic fibers to appropriately support the skin and its lymphatics is proposed as a possible contributing factor for chronic progressive lymphedema in Shires and Clydesdales.

Secondary lymphedema in the mouse tail: Lymphatic hyperplasia, VEGF-C upregulation, and the protective role of MMP-9

Disturbances in the microcirculation can lead to secondary lymphedema, a common pathological condition that, despite its frequency, still lacks a cure. Lymphedema is clinically well described, but while the genetic underpinnings that cause lymphatic malformations and primary lymphedema are being discovered, the pathophysiology and pathobiology of secondary lymphedema remain poorly understood, partly due to the lack of well-described experimental models. Here, we provide a detailed characterization of secondary lymphedema in the mouse tail and correlate the evolution of tissue swelling to changes in tissue architecture, infiltration of immune cells, deposition of lipids, and proliferation and morphology of the lymphatic vessels. We show that sustained swelling leads to lymphatic hyperplasia and upregulation of vascular endothelial growth factor (VEGF)-C, which may exacerbate the edema because the hyperplastic vessels are poorly functional. The onset of lymphatic hyperplasia occurred prior to the onset of lipid accumulation and peak VEGF-C expression. Langerhans dendritic cells were seen in the dermis migrating from the epidermis to the lymphatic capillaries in edematous tissue. Furthermore, these results were consistent between two different normal mouse strains, but swelling was significantly greater in a matrix metalloproteinase (MMP)-9 null strain. Thus, by characterizing this highly reproducible model of secondary lymphedema, we conclude that VEGF-C upregulation and lymphatic hyperplasia resulting from dermal lymphatic ligation and lymphedema leads to decreased drainage function and that MMP-9 may be important in counteracting tissue swelling.

Treatment of classic Kaposi's sarcoma-associated lymphedema with elastic stockings

Lymphedema of the lower extremities is a frequent complication of Kaposi's sarcoma (KS). Compressive therapy is the basis of treatment for lymphatic disorders, but to the authors' knowledge, there are no controlled trials to evaluate its effectiveness in KS-related lymphedema. Sixty-five patients with classic KS-associated lymphedema limited to below the knee were studied. Fifty patients received below-knee elastic stockings, whereas the remaining 15 did not use any compressive device. Among treated patients, 60% (30/50) experienced a limb volume reduction, while 40% (20/50) had an increase of limb volume. In contrast, all patients (15/15) of the untreated group had an increase of limb volume. No correlation between lymphedema reduction and systemic or local chemotherapy was observed, supporting compressive therapy as the major strategy for the treatment of this condition. Our results suggest that elastic stockings may be important tools for the management of lymphedema associated to classic KS.

Inflammatory manifestations of experimental lymphatic insufficiency

BACKGROUND

Sustained lymph stagnation engenders a pathological response that is complex and not well characterized. Tissue inflammation in lymphedema may reflect either an active or passive consequence of impaired immune traffic.

METHODS AND FINDINGS

We studied an experimental model of acute post-surgical lymphedema in the tails of female hairless, immunocompetent SKH-1 mice. We performed in vivo imaging of impaired immune traffic in experimental, murine acquired lymphatic insufficiency. We demonstrated impaired mobilization of immunocompetent cells from the lymphedematous region. These findings correlated with histopathological alterations and large-scale transcriptional profiling results. We found intense inflammatory changes in the dermis and the subdermis. The molecular pattern in the RNA extracted from the whole tissue was dominated by the upregulation of genes related to acute inflammation, immune response, complement activation, wound healing, fibrosis, and oxidative stress response.

CONCLUSIONS

We have characterized a mouse model of acute, acquired lymphedema using in vivo functional imaging and histopathological correlation. The model closely simulates the volume response, histopathology, and lymphoscintigraphic characteristics of human acquired lymphedema, and the response is accompanied by an increase in the number and size of microlymphatic structures in the lymphedematous cutaneous tissues. Molecular characterization through clustering of genes with known functions provides insights into processes and signaling pathways that compose the acute tissue response to lymph stagnation. Further study of genes identified through this effort will continue to elucidate the molecular mechanisms and lead to potential therapeutic strategies for lymphatic vascular insufficiency.

Inhibition of active lymph pump by simulated microgravity in rats

During spaceflight the normal head-to-foot hydrostatic pressure gradients are eliminated and body fluids shift toward the head, resulting in a diminished fluid volume in the legs and an increased fluid volume in the head, neck, and upper extremities. Lymphatic function is important in the maintenance of normal tissue fluid volume, but it is not clear how microgravity influences lymphatic pumping. We performed a detailed evaluation of the influence of simulated microgravity on lymphatic diameter, wall thickness, elastance, tone, and other measures of phasic contractility in isolated lymphatics. Head-down tail suspension (HDT) rats were used to simulate the effects of microgravity. Animals were exposed to HDT for 2 wk, after which data were collected and compared with the control non-HDT group. Lymphatics from four regional lymphatic beds (thoracic duct, cervical, mesenteric, and femoral lymphatics) were isolated, cannulated, and pressurized. Input and output pressures were adjusted to apply a range of transmural pressures and flows to the lymphatics. Simulated microgravity caused a potent inhibition of pressure/stretch-stimulated pumping in all four groups of lymphatics. The greatest inhibition was found in cervical lymphatics. These findings presumably are correlated to the cephalic fluid shifts that occur in HDT rats as well as those observed during spaceflight. Flow-dependent pump inhibition was increased after HDT, especially in the thoracic duct. Mesenteric lymphatics were less strongly influenced by HDT, which may support the idea that lymph hydrodynamic conditions in the mesenteric lymphatic during HDT are not dramatically altered.

Transcapillary fluid balance consequences of missing initial lymphatics studied in a mouse model of primary lymphoedema

To investigate the phenotypic consequences of a deranged lymphangiogenesis in relation to tissue fluid accumulation and the possible role of inflammation in the pathogenesis of lymphoedema, we measured determinants of transcapillary fluid filtration and inflammatory mediators in the interstitial fluid in genetically engineered Chy mice, a model for primary congenital lymphoedema (Milroy's disease). Although initial lymphatics were not present in dermis in any of the areas studied (fore paw, hind paw, thigh and back skin) interstitial fluid pressure (P(if)), measured with micropipettes, and tissue fluid volumes were significantly increased only in the areas with visible swelling - the fore and hind paw, whereas interstitial colloid osmotic pressure (COP(if)) was increased in all the skin areas examined. A volume load of 15% of body weight resulted in a more pronounced increase in P(if) as well as a four-fold increase in interstitial fluid volume in Chy relative to wild-type (wt) mice, showing the quantitative importance of lymphatics for fluid homeostasis during acute perturbations. A similar level of proinflammatory markers in interstitial fluid in early established lymphoedema (3-4 months) in Chy and wt suggests that inflammation does not have a major pathogenetic role for the development of lymphoedema, whereas a reduced level of the immunomodulatory cytokine interleukin (IL)-4 may result in a reduced immunological defence ability and thus lead to the increase in inflammatory cytokines IL-2 and IL-6 observed at a later stage (11-13 months). Our data suggest that primary lymphoedema results in a high interstitial fluid protein concentration that does not induce an interstitial inflammatory reaction per se, and furthermore shows the paramount importance of the initial lymphatics in tissue fluid homeostasis, especially during perturbations of transcapillary fluid balance.

Pretreatment lymphedema education and identified educational resources in breast cancer patients

OBJECTIVE

In 1998, the American Cancer Society (ACS) Lymphedema Workshop, called for a three phase approach to patient lymphedema education: (1) pretreatment, (2) postoperatively, and (3) continuing education. The objectives of this study were: to compare recalled pretreatment lymphedema education before and after the 1998 ACS call; compare recalled lymphedema pretreatment education between women with and without breast cancer treatment-related lymphedema; and identify breast cancer survivors perceived sources of lymphedema education.

METHODS

One hundred and forty-nine breast cancer survivors (74 with lymphedema and 75 without lymphedema) were asked: (1) Prior to having breast cancer treatment did anyone talk to you about your risk for lymphedema? If yes, who? (2) Prior to having breast cancer treatment did anyone talk to you about ways to decrease your risk for lymphedema? If yes, who? (3) If you want to learn more about lymphedema occurring after breast cancer treatment who would you ask or where would you look for information?

RESULTS

Individuals with lymphedema consistently recalled receiving less education and a decline in recalled risk reduction education in the lymphedema group occurred after 1998.

DISCUSSION

Barriers exist to the integration of ACS suggested pretreatment lymphedema educational protocols and risk reduction education may influence risk of developing lymphedema.

CONCLUSION

Pretreatment lymphedema education may improve breast cancer survivor's recall of educational information received about lymphedema.

PRACTICE IMPLICATIONS

Healthcare providers must be well versed about breast cancer treatment-related lymphedema and communicate this knowledge to patients on a consistent basis.

A pilot, prospective evaluation of a novel alternative for maintenance therapy of breast cancer-associated lymphedema [ISRCTN76522412]

Background

Prospective investigations of complete decongestive lymphatic physiotherapy (CDPT), including manual lymphatic drainage (MLD), have validated the efficacy of these interventions for the initial reduction of edema and long-term maintenance of limb volume in lymphedema. However, CDPT demands substantial time and effort from patients to maintain these benefits; the treatments are not always well-accepted, and patients may suffer from a deterioration in quality-of-life or a time-dependent loss of initial treatment benefits. A new device designed for home use by the patient, the Flexitouch™, has been developed to mechanically simulate MLD. We have undertaken a prospective, randomized, crossover study of the efficacy of the Flexitouch™, when compared to massage, in the self-administered maintenance therapy of lymphedema.

Methods

A prospective, randomized, crossover study of maintenance therapy was performed in 10 patients with unilateral breast cancer-associated lymphedema of the arm. Each observation phase included self-administered treatment with the Flexitouch™ or massage, 1 hour daily for 14 days, respectively, followed by crossover to the alternate treatment phase. Each treatment phase was preceded by a 1 week treatment washout, with use of garment only. The sequence of treatment was randomly assigned. The potential impact of treatment modality on quality of life was assessed with serial administration of the SF-36.

Results

Statistical analysis disclosed that the order of treatment had no outcome influence, permitting 10 comparisons within each treatment group. Post-treatment arm volume reduced significantly after the Flexitouch™, but not after self-administered massage. The patients' mean weight decreased significantly with Flexitouch™ use, but not with massage. The Flexitouch™ device was apparently well-tolerated and accepted by patients. Serial SF-36 administration showed no deterioration in physical or psychosocial scores compared to baseline measurements; there were no statistical differences in scores when the two treatment modalities were compared.

Conclusion

This short-term prospective evaluation of the Flexitouch™ suggests that the device may provide better maintenance edema control than self-adiminstered massage in breast cancer-associated lymphedema. The apparent ease of use and reliability of response to the device suggest that further broad-scale testing is warranted.

Lymphedema

Aggressively applied decongestive measures (ie, manual lymphatic drainage, low-stretch bandaging, exercise, skin care, application of compressive elastic garments) are the mainstay of lymphatic therapy. Therapeutic regimens should differentiate between the sequential goals of acute volume reduction and maintenance of limb volume. Elastic garments should not be employed until maximal volume reduction has been attained through decongestive lymphatic techniques. It is my opinion that use of intermittent pneumatic compression devices can play an important adjunctive role to decongestive lymphatic therapy but should not be substituted for these techniques. At this time, I am not inclined to use pharmacologic therapy in these patients but anxiously await the results of studies that might demonstrate efficacy for molecular approaches. Surgical intervention is reserved for a small number of well-selected patients. Liposuction for volume reduction appears to be a very promising approach for specific patients.

The lymphatic vasculature: recent progress and paradigms

The field of lymphatic research has been recently invigorated by the identification of genes and mechanisms that control various aspects of lymphatic development. We are beginning to understand how, starting from a subgroup of embryonic venous endothelial cells, the whole lymphatic system forms in a stepwise manner. The generation of genetically engineered mice with defects in different steps of the lymphangiogenic program has provided models that are increasing our understanding of the lymphatic system in health and disease. This knowledge, in turn, should lead to the development of better diagnostic methods and treatments of lymphatic disorders and tumor metastasis.

Lymphangiogenesis in development and human disease

The lymphatic vasculature forms a vessel network that drains interstitial fluid from tissues and returns it to the blood. Lymphatic vessels are also an essential part of the body's immune defence. They have an important role in the pathogenesis of several diseases, such as cancer, lymphoedema and various inflammatory conditions. Recent biological and technological developments in lymphatic vascular biology will lead to a better understanding and treatment of these diseases.

Signal transduction by VEGF receptors in regulation of angiogenesis and lymphangiogenesis

The VEGF/VPF (vascular endothelial growth factor/vascular permeability factor) ligands and receptors are crucial regulators of vasculogenesis, angiogenesis, lymphangiogenesis and vascular permeability in vertebrates. VEGF-A, the prototype VEGF ligand, binds and activates two tyrosine kinase receptors: VEGFR1 (Flt-1) and VEGFR2 (KDR/Flk-1). VEGFR1, which occurs in transmembrane and soluble forms, negatively regulates vasculogenesis and angiogenesis during early embryogenesis, but it also acts as a positive regulator of angiogenesis and inflammatory responses, playing a role in several human diseases such as rheumatoid arthritis and cancer. The soluble VEGFR1 is overexpressed in placenta in preeclampsia patients. VEGFR2 has critical functions in physiological and pathological angiogenesis through distinct signal transduction pathways regulating proliferation and migration of endothelial cells. VEGFR3, a receptor for the lymphatic growth factors VEGF-C and VEGF-D, but not for VEGF-A, regulates vascular and lymphatic endothelial cell function during embryogenesis. Loss-of-function variants of VEGFR3 have been identified in lymphedema. Formation of tumor lymphatics may be stimulated by tumor-produced VEGF-C, allowing increased spread of tumor metastases through the lymphatics. Mapping the signaling system of these important receptors may provide the knowledge necessary to suppress specific signaling pathways in major human diseases.

The Comparison of Two Different Physiotherapy Methods in Treatment of Lymphedema after Breast Surgery

BACKGROUND

The aim of this study was to compare two different physiotherapy methods in the treatment of lymphedema after breast surgery.

METHODS

This study was performed on 53 patients who had developed unilateral lymphedema after the breast cancer treatment. Twenty-seven patients served as the experimental group and were treated with complex decongestive physiotherapy (CDP) applications including lymph drainage, multi layer compression bandage, elevation, remedial exercises and skin care. Twenty-six patients in the control group were treated with standard physiotherapy (SP) applications including bandage, elevation, head-neck and shoulder exercises and skin care. Both groups were recommended a home program consisting of compression bandage exercises, skin care and walking. Patients were taken to a therapy program once a day; 3 days a week for 4 weeks. The range of motion, circumferential measurement, and volumetric measurement were assessed before and after treatment.

RESULTS

The overall improving in the CDP group was shown to be greater than the SP group but when the evaluation results of both groups were compared before and after treatment, a significant statistical difference in edema according to circumferential and volumetric measurements results was found in favor of the CDP group (p < 0.05).

CONCLUSION

In the patients with upper extremity lymphedema, the shoulder mobility can be increased and edema can be decreased by the use of complex physiotherapy programs.

Pathogenesis of persistent lymphatic vessel hyperplasia in chronic airway inflammation

Edema occurs in asthma and other inflammatory diseases when the rate of plasma leakage from blood vessels exceeds the drainage through lymphatic vessels and other routes. It is unclear to what extent lymphatic vessels grow to compensate for increased leakage during inflammation and what drives the lymphangiogenesis that does occur. We addressed these issues in mouse models of (a) chronic respiratory tract infection with Mycoplasma pulmonis and (b) adenoviral transduction of airway epithelium with VEGF family growth factors. Blood vessel remodeling and lymphangiogenesis were both robust in infected airways. Inhibition of VEGFR-3 signaling completely prevented the growth of lymphatic vessels but not blood vessels. Lack of lymphatic growth exaggerated mucosal edema and reduced the hypertrophy of draining lymph nodes. Airway dendritic cells, macrophages, neutrophils, and epithelial cells expressed the VEGFR-3 ligands VEGF-C or VEGF-D. Adenoviral delivery of either VEGF-C or VEGF-D evoked lymphangiogenesis without angiogenesis, whereas adenoviral VEGF had the opposite effect. After antibiotic treatment of the infection, inflammation and remodeling of blood vessels quickly subsided, but lymphatic vessels persisted. Together, these findings suggest that when lymphangiogenesis is impaired, airway inflammation may lead to bronchial lymphedema and exaggerated airflow obstruction. Correction of defective lymphangiogenesis may benefit the treatment of asthma and other inflammatory airway diseases.

Analyse comparative de la lymphoscintigraphie au cours des lipœdèmes et des lymphœdèmes primitifs des membres inférieurs

Lipedema is characterized by bilateral enlargement of the legs due to abnormal deposition of fat tissue from pelvis to ankles. It is seen most frequently in obese women. Lipedema appears to be a distinct clinical entity but may be confounded with lymphedema.

AIM OF THE STUDY

To analyze and to compare between lipedema and lymphedema the qualitative and quantitative aspects of lymphoscintigraphy.

METHODS

Fifteen women with lipedema were recruited. Mean age of onset of lipedema was 31.5 +/- 15 years. Body mass index was 35.1 +/- 7.9 kg/m2, 13 women were obese. Lipedema was compared to 15 cases of primary lymphedema (women: 13, men: 2) of the lower limbs (unilateral: 13, bilateral: 2), with a mean age at onset of 28.7 +/- 12.6 years. Lymphoscintigraphy of the lower limbs with morphologic (visualization of inguinal lymph nodes) and kinetic (half-life, lymphatic speed of the colloid) studies was performed in all cases.

RESULTS

Absence of visualization of inguinal lymph nodes was observed in 14/15 cases of lymphedema and in 1/15 cases of lipedema (p<0.001). In the 13 cases of unilateral lymphedema, colloid half-life was higher in the pathologic limb than in the controlateral limb (230 +/- 92 vs 121 +/- 36 minutes, p<0.01) and lymphatic speed of the colloid was slower (6.91 +/- 0.86 vs 8.16 +/- 1.02 cm/min, p<0.001). The two patients with bilateral lymphedema had an increased half-life and decreased lymphatic speed of the colloid. Colloid half-life was significantly higher in lipedema than in controlateral limbs of lymphedema (154 +/- 23 vs 121 +/- 36 minutes, p<0.01) with no difference in lymphatic speed of the colloid. Colloid half-life was significantly higher in lymphedema than in lipedema (230 +/- 92 vs 154 +/- 23 minutes, p<0.01) and the lymphatic speed of the colloid was slower (6.91 +/- 0.86 vs 8.10 +/- 0.45 cm/min, p<0.001).

CONCLUSION

Lower limb lymphoscintigraphy showed lymphatic insufficiency in lipedema without morphologic abnormality as seen in lymphedema. Lymphoscintigraphy is not indispensable but is a useful tool when diagnosis is doubtful. Treatment is difficult and may include weight loss and possible surgery.

Hereditary Vascular Anomalies

Increased understanding of the mechanisms of angiogenesis and lymphangiogenesis has provided a glimpse at some of the molecules involved in the pathophysiology of hemangiomas and vascular malformations. This review focuses on recent advances in our understanding of the mechanisms of angiogenesis/lymphangiogenesis and the differentiation of arterial, venous, and lymphatic vessels. We integrate this knowledge with new data obtained from genetic studies in humans, which have revealed a number of heretofore-unsuspected candidates involved in the development of familial vascular anomalies. We present a common infantile vascular tumor, hemangioma, and then focus on hereditary familial vascular and lymphatic malformations. We also summarize transgenic mouse models for some of these malformations. It seems reasonable to believe that novel therapeutic strategies will soon emerge for the treatment of hemangiomas and vascular malformations.

Selenium in the treatment of head and neck lymphedema

OBJECTIVE

To investigate the impact of selenium in the treatment of lymphedema of the head and neck region after radiotherapy alone or in combination with surgery.

SUBJECTS AND MATERIALS

Between June 1996 and June 2001 a total of 36 cancer patients (29 male, 7 female; median age 61 years) were treated with selenium for persistent, extensive or progressive lymphedema of the head and neck region. Twenty had interstitial endolaryngeal edema associated with stridor and dyspnea. All patients received 350 microg/m(2) body surface sodium selenite medication p.o. daily (total dose 50 microg per day) for a period of 4-6 weeks after radiotherapy. The optimal effect of the selenium treatment was assessed after 4 weeks of therapy using the Miller score system. A visual analogue scale on a scale of 0-10 was used to assess the patient's quality of life prior to and after selenium.

RESULTS

75% of the patients had an improvement of the Miller score of one stage or more. The self-assessment of quality of life using the visual analogue scale improved significantly after selenium treatment with a reduction of 4.4 points (p < 0.05). Of the 20 patients with endolaryngeal edema tracheostomy was not necessary in 13 patients (65%), but 5 and 2 received a temporary or permanent tracheostomy, respectively. No episode of erysipelas was observed in all study patients.

CONCLUSION

Our results suggest a short positive effect of sodium selenite on secondary head and neck lymphedema caused by radiotherapy alone or in combination with surgery.

Kaposiform hemangioendothelioma associated with Milroy's disease (primary hereditary lymphedema)

Kaposiform infantile hemangioendothelioma (KHE) is a rare recently characterized, locally aggressive, endothelial-derived neoplasm that occurs exclusively in the pediatric age group. Milroy-Nonne disease (primary hereditary lymphedema) is an uncommon congenital entity with familiar history of lower limb edema as typical clinical features. An 8-year-old boy developed a hard painless mass in the right leg 7 years after the diagnosis of congenital primary lymphedema of the right lower extremity. Histopathological analysis of the tumor showed the typical findings of the KHE. To our knowledge this is the first reported case of a KHE engrafting on this infrequent benign lymphatic anomaly.

Gene transfer as a tool to induce therapeutic vascular growth

Therapeutic induction of vascular growth may provide a treatment option for those patients with myocardial or peripheral ischemia who are not suited to conventional revascularization therapies. Some lymphatic vascular disorders may also be amenable to this therapy. However, clear evidence of efficacy must be obtained from phase 2 and 3 clinical trials before these new treatments can be entered into clinical practice. Apart from the clinical applications, gene transfer aimed at stimulating or blocking vascular growth with various growth factors, cytokines, transcription factors and receptors or their antagonists is useful for analyzing the effects of those molecules on the vasculature, especially when gene targeting results in lethality or when large animal models are required.

Selenium in the treatment of radiation-associated secondary lymphedema

PURPOSE

The aim of this explorative study was to evaluate the impact of selenium in the treatment of lymphedema after radiotherapy.

MATERIALS AND METHODS

Between June 1996 and June 2001, 12 patients with edema of the arm and 36 patients with edema of the head-and-neck region were treated with selenium for therapy-related lymphedema. Of these 36 patients, 20 had interstitial endolaryngeal edema associated with stridor and dyspnea. All patients received sodium selenite over 4 to 6 weeks.

RESULTS

Self-assessment using a visual analog scale (n = 48) showed a reduction of 4.3 points when comparing pre- and posttreatment values (p < 0.05). Of 20 patients with endolaryngeal edema, 13 underwent no tracheostomy, 5 underwent a temporary tracheostomy, and only 2 underwent a permanent tracheostomy. Ten of 12 patients with arm edema showed a circumference reduction of the edematous limb and improvement in the Skin-Fold Index by 23.3 points. An improvement of one stage or more was shown by the Földi or the Miller score (n = 28) in 22 (Földi score) and in 24 (Miller score) patients.

CONCLUSIONS

Treatment with sodium selenite is well tolerated and easy to deliver. Additionally, our results suggest that sodium selenite has a positive effect on secondary-developing lymphedema caused by radiation therapy alone or by irradiation after surgery.

Animal Models for the Study of Lymphatic Insufficiency

Lymphedema is the term commonly employed to describe the spectrum of pathological states that arise as a consequence of functional lymphatic insufficiency. These human disease entities currently lack an effective cure. Satisfactory therapeutic strategies for both primary and secondary lymphedema will require additional insight into the complex cellular mechanisms and responses that comprise both normal lymphatic function and its regional derangement in states of pathologic dysfunction. Such insights must, initially, be derived from suitable animal models of the chronic human disease process. Historically, efforts to replicate the untreated disease of human lymphedema in animals, through surgery, irradiation, and toxicology, have been fraught with difficulty. The major impediments to the creation of satisfactory animal models have included an inability to reproduce the chronic disease in a stable, reproducible format. Recently, with the promise of potentially successful growth factor-mediated therapeutic lymphangiogenesis, and with the enhanced availability of investigative tools to assess therapeutic responses to molecular therapies, there has been a resurgence of interest in the development of viable animal models of lymphatic insufficiency. Current research has led to the development of genetic and postsurgical models of lymphedema that closely simulate the human conditions of primary and secondary lymphatic insufficiency, respectively. Such models will help to refine the assessment of various therapeutic approaches and their potential applicability to human disease interventions.

Preclinical models of lymphatic disease: the potential for growth factor and gene therapy

The human disease states that are characterized by functional lymphatic insufficiency currently lack a cure. Molecular approaches may ultimately provide a therapeutic window to reverse the stigmata of both primary and secondary lymphatic insufficiency. To harness the potential therapeutic power of lymphangiogenesis, testing the safety and efficacy of the treatment response will be necessary. This, in turn, necessitates the availability of suitable preclinical animal models of the disease processes in question, along with suitable research tools to permit an assessment of the response to applied therapies. An ideal model would reproducibly and inexpensively replicate the untreated disease of human lymphedema. It would closely simulate the biology, as we understand it, of the human disease, and would replicate both the pathogenesis of the disease, including its natural history and the temporal patterns of its clinical expression. In this way, one might aspire to make valid predictions about the human applicability of therapy by extrapolation from observations in animal models. In addition to the availability of suitable animal models, the required investigative tools must also be available. In the context of lymphangiogenesis, to assess the therapeutic response, one must certainly possess the ability to recognize newly developed lymphatic vasculature. Sophisticated immunohistochemical and imaging techniques make this increasingly feasible. Initial experimental observations indicate that growth factor and gene therapy with VEGF-C holds promise for the treatment of both primary and secondary forms of lymphedema.

The molecular control of adipogenesis, with special reference to lymphatic pathology

Adipogenesis is the process by which mature fat cells are formed from pre-adipocytes. Adipogenesis has come under increasing scrutiny not only because the availability of reliable in vitro models makes it an attractive choice for developmental studies, but also because adipocytes are increasingly recognized as major players in a variety of physiological and pathophysiological states, such as obesity and type 2 diabetes. Adipocytes develop from mesenchymal stem cell precursors that are characterized by multipotency. Under the influence of various cues, these cells become committed to the adipocyte lineage. Further hormonal stimulation recruits these pre-adipocytes to accumulate lipid, express fat-specific markers, and become sensitive to the metabolic effects of insulin. A complex transcriptional cascade regulates this process, involving several distinct classes of transcription factor. In particular, the role of the nuclear hormone receptor PPARgamma will be discussed, along with bZip family members C/EBPalpha, C/EBPbeta, and C/EBPdelta. The relationship of adipose depots to the lymphatic system will also be discussed.

Therapeutic lymphangiogenesis with human recombinant VEGF-C

Chronic regional impairments of the lymphatic circulation often lead to striking architectural abnormalities in the lymphedematous tissues. Lymphedema is a common, disabling disease that currently lacks a cure. Vascular endothelial growth factors C and D mediate lymphangiogenesis through the VEGFR-3 receptor on lymphatic endothelia. The purpose of this study was to investigate the therapeutic potential for lymphangiogenesis with VEGF-C. We developed a rabbit ear model to simulate human chronic postsurgical lymphatic insufficiency. Successful, sustained surgical ablation of the ear lymphatics was confirmed by water displacement volumetry. After complete healing, the experimental animals (n=8) received a single, s.c. 100 microg dose of VEGF-C in the operated ear; controls (n=8) received normal saline. Radionuclide lymphoscintigraphy was performed to quantitate lymphatic function. Immunohistochemistry (IHC) was performed 7-8 days following treatment. After VEGF-C, there was a quantifiable amelioration of lymphatic function. IHC confirmed a significant increase in lymphatic vascularity, along with reversal of the intense tissue hypercellularity of untreated lymphedema. This study confirms the capacity of a single dose of VEGF-C to induce therapeutic lymphangiogenesis in acquired lymphedema. In addition to improving lymphatic function and vascularity, VEGF-C can apparently reverse the abnormalities in tissue architecture that accompany chronic lymphatic insufficiency.

Insights into the molecular pathogenesis and targeted treatment of lymphedema

Abnormal function of the lymphatic vessels is associated with a variety of diseases, such as tumor metastasis and lymphedema. The development of strategies for local and controlled induction or inhibition of lymphangiogenesis would thus be of major importance for the treatment of such diseases. Two growth factors, vascular endothelial growth factor C (VEGF-C) and D (VEGF-D), have been found to be important in the proper formation and maintenance of the lymphatic network, through their receptor VEGFR-3. In patients with lymphedema, heterozygous inactivation of VEGFR-3 leads to primary lymphedema due to defective lymphatic drainage in the limbs. We have shown that VEGF-C gene transfer to the skin of mice with lymphedema induces regeneration of the cutaneous lymphatic vessel network. However, as is the case with VEGF, high levels of VEGF-C cause blood vessel growth and leakiness, resulting in tissue edema. Strategies to avoid these side-effects have also been developed. This new field of reseach has important implications for the development of new therapies for human lymphedema.

Evaluation of the pathology, pathogenesis and aetiology of auricular elephantiasis in slaughter pigs

Ears from slaughter pigs with auricular elephantiasis (n = 24) and the corresponding lymph nodes (lnn.) (n = 26) were grossly, histopathologically and microbiologically examined. Immunostaining for IgM, IgG, Cd3epsilon and bacterial antigens of Arcanobacterium pyogenes and Staphylococcus aureus was performed by indirect enzyme-based techniques. Ears were variably thickened depending on the sampled area (basis, centre and apex). However, at all locations the thickness, the length from basis to apex and the weigh of whole ears with elephantiasis were significantly increased (P < 0.01). The corresponding lnn., that is, ln. parotideus superficialis and profundus, had also increased significantly (P < 0.01) in volume. Histopathologically, lesions of the ears and the corresponding lnn. revealed changes characterized by diffuse fibrosis intermingled with multiple pyogranulomatous foci containing asteroid bodies. In the majority of lesions, four distinct zones due to different cellular infiltrates encircled the central core of the asteroid bodies. In several lesions, the pyogranulomatous foci were contained within the lymph vessels. Immunohistochemically, only the bacterial antigen of S. aureus was detected within the cytoplasm of the macrophages and/or in the asteroid bodies of the ears (41.5%) and in the regional lnn. (30.8%). An abundant number of IgM, IgG and CD3epsilon-positive cells were present in all the pyogranulomatous lesions, whereas a positive IgG-staining was observed only in a single asteroid body. Thus, porcine auricular elephantiasis is a chronic pyogranulomatous inflammation that is frequently positive for S. aureus and is lymphogenically spread. Therefore, the lesions of the ears with auricular elephantiasis and the corresponding lnn. should be termed auricular botryomycosis and botryomycotic lymphadenitis, respectively. Moreover, as the disease is observed frequently in slaughter pigs it must also be considered according to the welfare of the animals and in relation to post-mortem meat inspection.

Proteomic technologies to study diseases of the lymphatic vascular system

Now that the human genome has been mapped, a new challenge has emerged: deciphering the various products of individual genes. Consequently, new proteomic technologies are being developed to monitor and identify protein function and interactions responsible for the total activities of the cell. The application of these new proteomic technologies to study cellular activities, will lead to a faster sample throughput and increased sensitivity for the detection of individual proteins, thus providing major opportunities for the discovery of new biomarkers for the early detection of protein alterations associated with the progression of the disease state.

Peripheral edema

Peripheral edema often poses a dilemma for the clinician because it is a nonspecific finding common to a host of diseases ranging from the benign to the potentially life threatening. A rational and systematic approach to the patient with edema allows for prompt and cost-effective diagnosis and treatment. This article reviews the pathophysiologic basis of edema formation as a foundation for understanding the mechanisms of edema formation in specific disease states, as well as the implications for treatment. Specific etiologies are reviewed to compare the diseases that manifest this common physical sign. Finally, we review the clinical approach to diagnosis and treatment strategies.

Breast cancer lymphedema: pathophysiology and risk reduction guidelines

PURPOSE/OBJECTIVES

To review the normal physiology of the blood capillary-interstitial-lymphatic vessel interface, describe the pathophysiology of lymphedema secondary to treatment for breast cancer, and summarize the physiologic bases of the current National Lymphedema Network (NLN) risk reduction guidelines.

DATA SOURCES

Journal articles, anatomy and physiology textbooks, published research data, and Web sites.

DATA SYNTHESIS

Lymphedema occurring after treatment for breast cancer significantly affects physical, psychological, and sexual functioning. About 28% of breast cancer survivors develop lymphedema. When arterial capillary filtration exceeds lymphatic transport capacity, lymphedema occurs. NLN risk reduction guidelines may decrease lymphedema risk.

CONCLUSION

Lymphedema is chronic and disfiguring. Most NLN risk reduction guidelines, although not evidence-based, are based on sound physiologic principles. Evidence-based research of the effectiveness of NLN risk reduction guidelines is indicated.

IMPLICATIONS FOR NURSING

Until evidence-based research contradicts NLN's risk reduction guidelines, nurses should inform patients with breast cancer about their risk for lymphedema, guidelines to reduce that risk, and the physiologic rationale for the guidelines.

The Law of Laplace and its relevance to contemporary medicine and rehabilitation

OBJECTIVE

To show that the Law of Laplace is not only a historical curiosity but also remains relevant to our daily teaching and clinical activities.

DATA SOURCES

Comprehensive MEDLINE (1960-2000) and CINAHL (1982-2000) computer literature searches performed by using key words such as Law of Laplace, Laplace, and Laplace relationship. Additional references were obtained from the bibliographies of the selected articles. Supplementary searches were also made by using various Internet search engines.

STUDY SELECTION

Primary references were used whenever possible.

DATA EXTRACTION

A single reviewer assessed all references and extracted information relevant to the Law of Laplace.

DATA SYNTHESIS

Although the Law of Laplace is attributed to Pierre Simon de Laplace, Laplace may not deserve the credit for the discovery. Nevertheless, the relationship (T [tension] alpha P [pressure] R [radius]) is easily derived and improves our understanding of the physiologic basis of many of our medical and rehabilitation practices. For example, the Law provides an insight into the mechanism of action of compression garments and lumbosacral orthoses, an understanding of the role of uterine muscle during delivery, and a reason why cesarean sections are made in the lower uterus. In addition, the Law explains many aspects of such diverse phenomena as penile erection, compartment syndromes, and peripheral edema. Perhaps most important, the Law explains the basis of many common medical practices that we use to promote bladder emptying, to control edema, and to plan surgery.

CONCLUSION

The Law of Laplace explains the mechanism of a wide range of physiologic phenomena. Unfortunately, even though it was developed about 200 years ago, the insights it provides us are often underused. More consideration of its implications can improve our clinical practice, our teaching, and our enjoyment of medicine.

[Lymphology in 2002. From diagnosis to treatment of lymphedemas]

Lymphedema are primary (lower limb) or secondary for the upper limb after treatment of breast cancer. Genetic research allows to explain better pathophysiology of lymphedema. Lymphoscintigraphy is the main imaging technique for lymphedema. Venous or compressive etiologies may be first excluded. Treatment of lymphedema includes decongestive physiotherapy: manual lymph drainages, bandages, elastic stockings, exercises, skin care to avoid infections. Other treatments may be associated: weight loss, drugs (procyanidolic oligomers), surgery for genital lymphedema, pneumatic compression pumps for lymphovenous insufficiency.

[Physiopathology of lymphedema]

Edema is defined as an excess of interstitial fluids. Its appearance is always linked to a relative functional insufficiency of the lymphatic drainage, but the use of the word lymphedema is restricted to the conditions where the lymphatic insufficiency is the primary pathogenetic factor of edema formation. The lymphatic insufficiency may result from: 1) an incompetence of the lymphatic capillaries, either due to their aplasia (Milroy's disease) or to their destruction (lipodermatosclerosis of chronic venous insufficiency); 2) an insufficiency of the lymphatic collectors related to their hypoplasia (primary lymphedema), or their destruction by trauma, infection or carcinologic treatments; a drug related functional insufficiency of lymphatic collectors is probable, but more data are needed on this topic; 3) pathologic lymphatic nodes (surgical excision, invasion by hematological disorders or cancer) could interfere with their ability to concentrate lymphatic fluids. Local tissue changes in the lymphedematous limbs are important and should be taken into account in the care management of such patients.

[Management of lymphedema: experience of the Cognacq-Jay Hospital]

Treatment of lymphedema includes practical advices, manual lymph drainage, bandaging, self-bandaging, elastic compression garment, skin care and physical exercises. Weight loss may be useful if obesity. Surgery is indicated in genital lymphedema more than in limb lymphedema. In 2001, in Lymphology Unit, 248 women were treated for secondary upper limb lymphedema after breast cancer. Excess of volume of lymphedema was reduced by 31.3% after a mean time of 2.1 weeks. For lower limb lymphedema (primary or secondary), 136 patients were treated with a mean reduction of excess of lymphedema by 29.8% after a mean time of 2.2 weeks. After this treatment, long term follow-up is necessary to maintain results and the motivation of the patient.

Lymphatic endothelial regulation, lymphoedema, and lymph node metastasis

Vascular endothelial growth factor receptor-3 (VEGFR-3) mediates lymphatic endothelial cell (LEC) growth, migration, and survival by binding VEGF-C and VEGF-D. Recent studies have revealed new regulators of the lymphatic endothelium, such as the transcription factor Prox1, and the cell surface proteins podoplanin and lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1). Furthermore, the isolation of LECs now allows detailed molecular studies of the factors regulating the lymphatic vasculature. These studies are aimed at targeting the lymphatic vasculature in the treatment of various diseases, such as tumour metastasis and lymphoedema.

Lymphatic endothelium: a new frontier of metastasis research

The vascular endothelium is a dynamic tissue with many active functions. Until recently, endothelial cell (EC) biology studies have used cultured ECs from various organs; these cell lines are considered representative of the blood vascular endothelium. Very few lymphatic EC lines have been available, and these were derived from lymphatic tumours or large collecting lymphatic ducts. In the past, lymphatic vessels were defined largely by the lack of erythrocytes in their lumen, a lack of junctional complexes and the lack of a well-defined basement membrane. Now that lymphatic-specific vascular endothelial growth factors (VEGF-C and VEGF-D) and molecular cell surface markers such as the VEGFR-3 receptor have been identified, this definition needs to be updated. Recent developments have highlighted the importance of lymphatic ECs, and they could become the next focus for angiogenesis and metastasis research.