Lymphatic circulation in astronauts: basic knowledge, challenges and perspectives.

Space missions expose the astronauts' bodies to various stressors, including microgravity. While numerous studies have investigated the effects of this stressor, research on its impact on the lymphatic system remains confidential. This review highlights the importance of scientific research into the human lymphatic system exposed to long-duration space missions. The safety of astronauts is a major issue. Chronic slowing of lymphatic drainage disrupts the balance of fluid and macromolecule exchange within poorly drained anatomical areas. Their extracellular matrix gradually becomes the site of dispersed deposits of degraded proteins and increased local water content. The interaction between these two phenomena leads to mutual amplification, resulting in a slow, gradual increase in pressure within the impacted tissue, which undergoes an expansion known as edema. The speed at which these pathophysiological processes take hold includes the extent of the lymphatic insufficiency and any compensatory measures that may or may not be put in place. Lymphatics are present everywhere in the body where tissues receive blood. Organs such as the brain, heart, and intestines, among others, as well as local immune function, can be damaged over time when their lymphatic system becomes chronically insufficient. The human clinical experience of lymphatic insufficiency tells us that the onset of edema takes time and is an insidious but inevitable phenomenon if adequate compensation does not occur. The time required for the pathophysiological consequences of lymphatic insufficiency to become established does not coincide with the time allocated to bed rest experiments or current space missions. With the prospect of longer space missions, lymphatic insufficiency linked to microgravity could unexpectedly become a major obstacle to human life in space.

Steroid-converting enzymes in human adipose tissues and fat deposition with a focus on AKR1C enzymes.

Adipocytes express various enzymes, such as aldo-keto reductases (AKR1C), 11ß-hydroxysteroid dehydrogenase (11ß-HSD), aromatase, 5α-reductases, 3ß-HSD, and 17ß-HSDs involved in steroid hormone metabolism in adipose tissues. Increased activity of AKR1C enzymes and their expression in mature adipocytes might indicate the association of these enzymes with subcutaneous adipose tissue deposition. The inactivation of androgens by AKR1C enzymes increases adipogenesis and fat mass, particularly subcutaneous fat. AKR1C also causes reduction of estrone, a weak estrogen, to produce 17ß-estradiol, a potent estrogen and, in addition, it plays a role in progesterone metabolism. Functional impairments of adipose tissue and imbalance of steroid biosynthesis could lead to metabolic disturbances. In this review, we will focus on the enzymes involved in steroid metabolism and fat tissue deposition.

SVEP1 is important for morphogenesis of lymphatic system: Possible implications in lymphedema.

SVEP1, also known as Polydom, is a large extracellular mosaic protein with functions in protein interactions and adhesion. Since Svep1 knockout animals show severe edema and lymphatic system malformations, the aim of this study is to evaluate the presence of SVEP1 variants in patients with lymphedema. We analyzed DNA from 246 lymphedema patients for variants in known lymphedema genes, 235 of whom tested negative and underwent a second testing for new candidate genes, including SVEP1, as reported here. We found three samples with rare heterozygous missense single-nucleotide variants in the SVEP1 gene. In one family, healthy members were found to carry the same variants and reported some subclinical edema. Based on our findings and a review of the literature, we propose SVEP1 as a candidate gene that should be sequenced in patients with lymphatic malformations, with or without lymphedema, in order to investigate and add evidence on its possible involvement in the development of lymphedema.

Breast implant infection with pasteurella canis: First case-report.

Zoonotic infections represent an uncommon phenomenon. Few people with pets realise the infectious risk this entails. This case describes a Pasteurella canis infection of a breast implant following close contact between a patient and her cat. A 59-year-old woman developed infection of her breast implant 7 months after implantation. Surgical revision was performed after failure of conservative treatment with antibiotics. Perioperative samples from the periprosthetic fluid were positive for P. canis, a Gram-negative coccobacillus that is present in the oropharyngeal commensal flora of cats and dogs. History revealed that the patient owned a cat for 2 years. This case highlights the possible risk of zoonotic infections in humans with protheses following close contact with a cat. Antibiotic therapy and surgical revision, with or without removal of the prosthesis constitute the cornerstone of treatment in such cases.

The Chondroepitrochlearis Muscle: A Rare Cause of Axillary Vein Thrombosis and Lymphedema.

The chondroepitrochlearis muscle is a rare anomaly of the pectoralis major crossing over the neurovascular bundle in the axilla. Often associated with other supernumerary muscles like the arch of Langer, it has been reported in the past as a cause of restriction of arm abduction, cosmetic defects and compression of the ulnary nerve. This case report describes the first known vascular complication due to a chondroepitrochlearis muscle, causing intermittent compression of the axillary vein and thrombosis, associated with pain, upper limb lymphedema, and impaired movements. The diagnosis was suspected from the medical history and confirmed by palpation and dynamic ultrasonography. Surgery was performed to divide the muscle slip with the help of lymphofluoroscopy to prevent damage to the lymphatic structures. Pain and impairment of movement disappeared within a few days after surgery and lymphedema decreased significantly.

Contributions of SPECT/CT imaging to the lymphoscintigraphic investigations of the lower limb lymphedema.

Lymphoscintigraphy is a safe and reliable technique for investigating lymphedema. However, interpretation of delayed planar conventional imaging may be questionable due to the superimposition of soft tissues. Therefore, the aim of this retrospective study was to evaluate the contribution of single photon emission computed tomography/computed tomography (SPECT/CT) to lymphoscintigraphic investigation in a selected population with abnormal interstitial activity. Forty one patients with lower limb lymphedema either primary (n=17) or secondary (n=5), or associated with chronic venous insufficiency (n=19) underwent lymphoscintigraphy according to a standard protocol. SPECT/CT imaging that started immediately after planar imaging covered the part of the lower limbs with the most significant interstitial activity. The CT images were also analyzed separately to identify the typical honeycomb pattern of lymphedema. SPECT/CT identified additional abnormalities in vessels and soft tissues in 19 patients (46%). The additional information, primarily related to dermal collateralization of flow, dermal backflow, lymphangioma, and lymphorrhea, aided in understanding the physiopathology of edema and may have influenced management in 35 patients (85%). The honeycomb appearance of the soft tissues was noted on CT in most patients (90%). This study suggests that SPECT/CT is a promising addition to planar imaging in lymphoscintigraphic investigations of lymphedema.

Effect of lateralization and handedness on the function of the lymphatic system of the upper limbs.

In the upper limbs (UL), lateralization or handedness coincides with functional (and/or anatomical) asymmetries. Scintigraphic techniques were used to investigate the function of the UL lymphatic system and to determine whether significant differences exist between right and left limbs. With limbs at rest, 99mTc-labeled HSA nanosized colloids were injected intradermally into the forearms in 19 volunteers. Activities in the axillary nodes were recorded 1 minute later, then every 20 minutes up to100 minutes later and reported as per ten thousands of injected activity. When comparing right injections to left injections, no significant difference was found using an unpaired statistical test. However, with paired t-tests, axillary node activity (mean +/- SD) was significantly higher when the right limb was injected than when the left limb was injected, both overall (n = 19) (at 100 minutes: 454 +/- 88 versus 299 +/- 45: p = 0.014) and when the 13 right-handed cases were analyzed separately (501 +/- 116 versus 285 +/- 65: p = 0.004). No difference was found for the six left-handed volunteers. Our results demonstrate, at least in the right handed subjects, the functional asymmetry of the superficial lymphatic system of the right and left upper limbs.

[Limb edema and lymphoscintigraphy]. / Oedèmes des membres et lymphoscintigraphies.

Lymphoscintigraphic investigations represent techniques of nuclear medicine very contributive for the management and treatment of the limb edemas, either primary or secundary. Their principle is presented and methodologies proposed in the literature are reviewed. Their diagnostic contributions are detailed. The sensitivities and specificities of several protocols of investigation are reported. Some limitations of these examinations are analyzed and discussed. Clinical indications for their use are proposed and their interest with regard to the various treatments that can be applied to these limb edemas is discussed.

The physical treatment of upper limb edema.

BACKGROUND: Edema of the upper limb, without any doubt, constitutes the most invalidating complication of breast carcinoma treatment. The swelling of the limb results from decreased liquid evacuation by surgical intervention at the axillary level and also by the eventual treatment by cobaltotherapy. METHOD: The physical treatment for edema of the limb consists of a combination of therapies that were tested for their effectiveness in laboratories on healthy students and also on patients who underwent surgery for breast carcinoma. The treatment consists of the application of manual lymphatic drainage (type Leduc), the use of multilayered bandages, and the use of intermittent pneumatic compression. The population studied was represented by 220 patients who underwent breast surgery. The authors followed their evolution during the first 2 weeks of treatment. Patients were not hospitalized. The edema was measured by using marks tattooed on the skin. RESULTS: The limb that developed edema was compared with the healthy limb. The most important reduction was obtained in the first week. The decrease was equivalent to 50% of the average of the difference between both upper limbs. During the second week, the results obtained stabilized; however, there was a slight decrease at the end of the second week. CONCLUSIONS: The physical treatment of edema represents the preferred therapeutic approach. However, it must answer to well-defined criteria to be efficient and for long-lasting effects. The physical treatment is used to treat outpatients, allowing them to follow a normal lifestyle.