Charles L. Witte

Angiopoietin-2 Is Required for Postnatal Angiogenesis and Lymphatic Patterning, and Only the Latter Role Is Rescued by Angiopoietin-1

VEGF and Angiopoietin-1 requisitely collaborate during blood vessel development. While Angiopoietin-1 obligately activates its Tie2 receptor, Angiopoietin-2 can activate Tie2 on some cells, while it blocks Tie2 activation on others. Our analysis of mice lacking Angiopoietin-2 reveals that Angiopoietin-2 is dispensable for embryonic vascular development but is requisite for subsequent angiogenic remodeling. Unexpectedly, mice lacking Angiopoietin-2 also exhibit major lymphatic vessel defects. Genetic rescue with Angiopoietin-1 corrects the lymphatic, but not the angiogenesis, defects, suggesting that Angiopoietin-2 acts as a Tie2 agonist in the former setting, but as an antagonist in the latter setting. Our studies define a vascular growth factor whose primary role is in postnatal angiogenic remodeling and also demonstrate that members of the VEGF and Angiopoietin families collaborate during development of the lymphatic vasculature.

Critical splenic mass for survival from experimental pneumococcemia

Survival after intravenous challenge with live Streptococcus pneumoniae (type III) over a wide dose range (102, 103, 104, 105, 106, 107) was examined in 686 Sprague-Dawley rats. These included Sprague-Dawley rats with varying splenic mass (25 to 300 mg) after graded partial amputation of the spleen (graded hyposplenia) (425 rats), total splenectomy (asplenia) (145 rats), and sham operation (eusplenia) (116 rats). Large (300 mg) but not small (< 100 mg) splenic remnants showed protection greater than asplenia (P < 0.001) and comparable to eusplenia while remnants of intermediate size (200 mg) showed intermediate protection—that is, greater than asplenia (P < 0.02) but less than eusplenia (P < 0.02). Moreover, the greater the spleen mass, the higher the LD50—thus 2.2 × 103 for no spleen; 3.3 × 103 for 25 mg; 8.1 × 103 for 100 mg; 5.2 × 104 for 200 mg; 1.8 × 105 for 300 mg and 9.9 × 105 for whole spleen. Apparently, a critical mass of spleen (more than one-third) is needed to restore host resistance to fatal blood-borne infection from this encapsulated microorganism.

Lymphangiogenesis: Mechanisms, significance and clinical implications

Great attention has been directed toward understanding angiogenesis over the past several decades since this phenomenon was reproduced in vitro in endothelial cell and mixed vascular tissue cultures (Folkman and Hauden-schild, 1980; Folkman, 1995). The focus, however, has been almost entirely on blood vessel growth, or what we have termed “hemangiogenesis” (M. Witte and Witte, 1987 c). Yet a vast interstitial fluid circulation suffuses the tissues, bathes the parenchymal cells and interconnects with the blood vasculature via the lymphatic vasculature (Fig. 1). This arc of the circulatory system on the dark side of the blood-tissue interface and its growth (“lymphangiogenesis”) has received scant attention even though lymphatic (re)generation is both vigorous and essential, and disorders of lymphatic dynamics are common, often disfiguring, and occasionally life- and limb-threatening.

Protean manifestations of pylethrombosis. A review of thirty-four patients.

Thirty-four adult patients with portomesenteric venous occlusion (PVO) were reviewed. In 11 with hepatic cirrhosis, PVO was usually heralded by worsening ascites often with varix hemorrhage; mortality was high. Four with isolated portal block had varix hemorrhage without ascites. All of these patients survived despite recurrent hematemesis when portal decompression was not feasible in two patients. Eight others (5 agnogenic and 3 with hypercoagulability), experienced sudden abdominal pain with a clot typically propagated into mesenteric tributaries with ileojejunal infarction; survival was related to the promptness of operation and the extent of bowel ischemia. Of five patients with intraabdominal sepsis and pylephlebitis, only one survived. In the final six patients, PVO occurred with intraabdominal carcinoma. Five had progressive ascites, cachexia, and an early death. Imaging techniques included plain and contrast roentgenograms, ultrasonography, and for definitive diagnosis direct portography (operative or splenoportogram), indirect portography (splanchnic arteriovenogram), and computed tomography. Thirteen of 34 patients had ascites, and in nine of 11 patients examined, protein concentration of ascitic fluid was extremely low (less than 0.6 g/dl). Clinical presentation of PVO varies, depending on acuteness and extent of visceral venous blockade, severity of portal hypertension, auxiliary venous collateralization, and regional lymph flow. Inciting factors include endothelial damage and blood hypercoagulability from trauma, infection, stagnant circulation, blood dyscrasia, and malignancy. Improved imaging now allows early diagnosis.

Radionuclide lymphangioscintigraphy in the evaluation of peripheral lymphedema.

PURPOSE The primary difficulty in evaluating and treating peripheral lymphedema is visualization of the lymphatics. Functional lymphatic studies have been performed on patients with peripheral edema to diagnose lymphedema, to determine its severity, and to understand the varied drainage patterns. METHODS After intradermal injection in the hands or feet, initial flow and whole-body images were taken using Tc-99m human serum albumin in more than 700 patients with possible lymphedema. RESULTS Clear images of truncal lymph transport and draining lymph nodes were obtained, and pattern differences between primary and secondary lymphedema were seen. Follow-up studies showed any functional change in lymphatic dynamics. CONCLUSION Peripheral lymphatics can now be easily visualized. Because lymphangioscintigraphy can be performed before and after medical treatment, follow-up evaluation of patients with lymphedema is possible. The procedure is noninvasive, repeatable, easy to perform, and harmless to the lymphatic endothelium.

Lymph Circulation in Hepatic Cirrhosis: Effect of Portacaval Shunt

Abstract To determine the relative contribution of the liver and extrahepatic portal bed to increased flow of thoracic duct lymph in hepatic cirrhosis, thoracic duct lymph was examined in 84 patien...

Inhibition of normal and experimental angiotumor endothelial cell proliferation and cell cycle progression by 2-methoxyestradiol.

Abstract With rapid growth and metabolism, aggressive cancers require an extensive vascular network, termed tumor angiogenesis. The body produces a variety of natural angiogenic inhibitors, among which is the mammalian estrogen metabolite, 2-methoxyestradiol (2-MeOE2). In this study, we compared the effects of 2-MeOE2 on a human umbilical vein cell line (HUVEC-C) and on an immortal, angiotumor-producing rat sinusoidal endothelial cell line (RSE-1). In vitro, the effects of varying concentrations of 2-MeOE2 from 0.01-100.0 μM were measured with cell counts and compared to control cells. HUVEC-C had an ED50 ~3.5 μM with ~27% inhibition of cell growth whereas RSE-1 had an ED50 ~2.2 μM with ~50% inhibition of cell growth compared with controls. The lowest concentration with maximal effect was 10.0 μM2-MeOE2 for both cell lines. Using this concentration, flow cytometric analysis of cell cycles was performed with propidium iodide stained DNA of HUVEC-C and RSE-1 at 24 and 48 hr. Both demonstrated a significant (P < 0.0001) block at G2M of the cell cycle. At 48 hr, HUVEC-C had 32% of cells in G2M (control = 9% G2M), and RSE-1 had 36% of cells in G2M (control = 18% G2M). These findings demonstrate a strong in vitro antiproliferative effect of 2-MeOE2 on normal dividing endothelial as well as angiotumor cells mediated through a cell cycle-specific block at G2M. The antiendothelial, antiangiotumor effect of 2-MeOE2 supports its potential as a therapeutic agent against solid organ cancers, benign or malignant vascular growths, and other pathologic states dependent on angiogenesis.

Segregation analyses and a genome‐wide linkage search confirm genetic heterogeneity and suggest oligogenic inheritance in some Milroy congenital primary lymphedema families

We previously described six families with Milroy congenital lymphedema, only one of which showed possible linkage to a candidate locus on chromosome 5 [Witte et al., 1998]. We have now performed a complex segregation analysis of these families, and performed linkage analyses with the other 387 markers used in our genome-wide search. Our results confirm that Milroy lymphedema is generally inherited as a dominant condition. However, this mode of inheritance, as elucidated from the segregation analyses, did not account for all observed familial correlations. The segregation analysis also suggested that shared environmental or additional genetic factors are important in explaining the observed familial aggregation. The finding of linkage to multiple locations in the largest family studied by multipoint parametric mapping (one of which was confirmed by sib-pair non-parametric mapping), suggests that Milroy congenital lymphedema may be oligogenic in this family.

Kaposi's Sarcoma A Lymphologic Perspective

The purpose of this article is to trace one central theme interwomen in the Kaposis sarcoma story almost from its original description, and mamely the relationship of Kaposis sarcoma to the lymphatic system

Massage therapy in the treatment of lymphedema

Lymphedema (LE) afflicts hundreds of millions people worldwide. Manual lymph drainage, a specialized form of massage therapy, is an integral component - along with compression bandaging (CB) - of combined physical therapy (CPT), an internationally recommended optimal treatment. Experimental data from a rat model of obstructive LE suggests that massage alone can reduce LE volume as effectively as CB and CPT, at least early in the pathologic process. In a preliminary retrospective clinical study, it was also found that massage alone in a cohort of patients with mild stable upper-limb LE was as effective as CPT in volume reduction (massage 80.6 /spl plusmn/ 0.2% decrease compared to CPT 72.6 /spl plusmn/ 0.2%, mean /spl plusmn/ standard deviation, not significant). These initial studies lay the groundwork and evidence-based rationale for the design and implementation of the expanded, prospective randomized clinical trial of massage alone in various types and stages of LE in children and adults.