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Lymphatic Capillaries (lymphatic + capillary)

Distribution by Scientific Domains

Medical Sciences	100%

Selected Abstracts

Lymphatic Vessels in Pancreatic Islets Implanted Under the Renal Capsule of Rats

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 4 2006
Ö. Källskog
Transplantation of pancreatic islets necessitates an engraftment process, including revascularization of the graft. Studies of graft vasculature have demonstrated that islets become revascularized during the first post-transplant week through an angiogenic process. If this also involves lymphatic vessels is unknown. The aim of the present study was to functionally evaluate if lymphatic vessels, which are absent in endogenous islets, form after islet transplantation. To achieve this, inbred Wistar-Furth rats were transplanted with 250 syngeneic islets under the renal capsule. Intra-vital microscopy of the graft in combination with interstitial injection of Evans Blue was performed 1 week, 1 month or 9,12 months later. In all animals studied, there was drainage through intra-graft lymphatic capillaries emptying into larger lymphatic vessels associated with the renal capsule. The number was slightly lower 1 week post-transplantation. Most of the lymphatic capillaries were present in the graft stroma, rather than interspersed among the endocrine cells. In some animals, we were able to demonstrate dye in regional lymph nodes. We conclude that unlike endogenous islets, islet grafts develop a lymphatic drainage. Its functional importance and characteristics remain to be established. However, it can be speculated that immune reactions may be facilitated by the presence of lymphatic vessels. [source]

Decreased lymphatic vessel counts in patients with systemic sclerosis: Association with fingertip ulcers

ARTHRITIS & RHEUMATISM, Issue 5 2010
Alfiya Akhmetshina
Objective Systemic sclerosis (SSc) is a connective tissue disease that is characterized by microvascular disease and tissue fibrosis. Progressive loss and irregular architecture of the small blood vessels are well characterized, but the potential involvement of the lymphatic vessel system has not been analyzed directly in SSc. This study was undertaken to assess whether the lymphatic vascular system is affected in SSc, and whether changes to the lymphatic vessels are associated with dystrophic changes and tissue damage in patients with SSc. Methods Lymphatic endothelial cells in skin biopsy samples from patients with SSc and age- and sex-matched healthy volunteers were identified by staining for podoplanin and prox-1, both of which are specifically expressed in lymphatic endothelial cells but not in blood vascular endothelial cells. CD31 was used as a pan,endothelial cell marker. Statistical analyses were performed using Kruskal-Wallis, Mann-Whitney U, and Spearman's rank correlation tests. Results The numbers of podoplanin- and prox-1,positive lymphatic vessels were significantly reduced in patients with SSc as compared with healthy individuals. The number of podoplanin-positive lymphatic precollector vessels was significantly lower in SSc patients with fingertip ulcers than in SSc patients without ulcers. Moreover, the number of lymphatic vessels correlated inversely with the number of fingertip ulcers at the time of biopsy and with the number of fingertip ulcers per year. The inverse correlation between lymphatic precollector vessel counts and fingertip ulcers remained significant after statistical adjustment for the blood vessel count, age, and modified Rodnan skin thickness score. Conclusion These results demonstrate a severe reduction in the number of lymphatic capillaries and lymphatic precollector vessels in patients with SSc. Patients with decreased lymphatic vessel counts may be at particularly high risk of developing fingertip ulcers. [source]

Does stereoselective lymphatic absorption contribute to the enantioselective pharmacokinetics of halofantrine In Vivo?

BIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 4 2003
David M. Shackleford
Abstract Halofantrine (Hf) is a chiral, lipophilic phenanthrene methanol antimalarial which exhibits both enantioselective plasma pharmacokinetics and extensive lymphatic absorption when administered postprandially. In order to determine whether enantioselective lymphatic absorption contributes to the previously reported enantioselective pharmacokinetics of Hf, lymph samples collected from thoracic duct-cannulated dogs dosed with racemic Hf (100 mg, administered postprandially) were assayed with a chiral HPLC method capable of quantifying the relative amounts of (+)- and (,)-Hf. During the period when the majority (>95%) of Hf transport into lymph occurred (0,5 h post dose), essentially equal amounts of the two enantiomers were present in the intestinal lymph. At later times (e.g. 5,12 h post dose), there was a steady increase in the fraction of (+)-Hf present in lymph. The trends evident at later time points most likely reflect an increase in the proportion of (+)-Hf present in systemic blood, (resulting from enantioselective systemic metabolism) and a corresponding increase in (+)-Hf in the thoracic lymph by equilibration of drug across blood and lymphatic capillaries, as opposed to enantioselective lymphatic transport per se. This study was the first to examine the possibility of stereoselectivity in lymphatic transport, however, the data suggest that drug absorption (at least in the case of halofantrine) via the intestinal lymphatics is not enantioselective. Copyright © 2003 John Wiley & Sons, Ltd. [source]