Low-density Fat Research Articles

Condensing of Low-Density Fat by Mechanical Process Improves Fat Retention and Reduces Oil Cyst Formation in Breast Reconstruction.

Although autologous fat grafting is a useful adjunct for breast reconstruction, its indications remain limited as large-volume fat grafting results in high absorption and complication rates. Low-density fat includes small numbers of viable cells and considerable oil, resulting in nodules and oil cysts. This study evaluated the volumization effect and complications with combined fat grafting of condense low-density fat and high-density fat. This retrospective, single-center study included 25 patients who underwent combined grafting of condensed low-density fat and high-density fat (CLDF + HDF) and 20 patients who underwent conventional Coleman fat grafting for breast reconstruction from December 2017 to January 2022. Retention rates and complications were evaluated by magnetic resonance imaging and ultrasound rates. Patient satisfaction was evaluated using a typical Likert scale. Photographs were taken and imageological examinations were performed before and after treatment. Graft retention rate was higher in patients who underwent CLDF + HDF than Coleman fat grafting for breast reconstruction (38.40 ± 4.41% vs. 31.43 ± 5.43%, p <0.05). One patient in the CLDF + HDF grafting group, compared with twelve in the Coleman fat grafting group, developed oil cysts exceeding 1 cm. Patient satisfaction rate was higher in the CLDF + HDF grafting group. Mechanical processes can concentrate the cellular content of LDF and remove oil, condensing LDF to the level of HDF. Combined grafting of CLDF optimized by mechanical processing and HDF is effective for breast reconstruction, with a higher retention rate and a lower incidence of complications than conventional Coleman fat grafting. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Connecting Non-Gaussian Water Density Fluctuations to the Lengthscale Dependent Crossover in Hydrophobic Hydration.

We connect density fluctuations in liquid water to lengthscale dependent crossover in hydrophobic hydration. Specifically, we employ indirect umbrella sampling (INDUS) simulations to characterize density fluctuations in observation volumes of various sizes and shapes in water and as a function of temperature and salt concentration. Consistent with previous observations, density fluctuations are Gaussian in small molecular scale volumes, but they display non-Gaussian "low-density fat tails" in larger volumes. These non-Gaussian tails are indicative of the proximity of water to its liquid to vapor phase transition and have implications on biomolecular interactions and function. We show that the onset of non-Gaussian fluctuations in large volumes is accompanied by the formation of a cavity in the observation volume. We develop a model that uses the physics of cavity-water interface formation as a key ingredient and show that it captures the nature of non-Gaussian density fluctuations over a broad region in water and in salt solutions. We discuss the limitations of this model in the very low density region of the distribution. Our calculations provide new insights into the origins of non-Gaussian density fluctuations in water and their connections to lengthscale dependent crossover in hydrophobic hydration.

Mechanical Micronization of Lipoaspirates for Regenerative Therapy.

Stromal vascular fraction (SVF) has become a regenerative tool for various diseases; however, legislation strictly regulates the clinical application of cell products using collagenase. Here, we present a protocol to generate an injectable mixture of SVF cells and native extracellular matrix from adipose tissue by a purely mechanical process. Lipoaspirates are put into a centrifuge and spun at 1,200 x g for 3 min. The middle layer is collected and separated into two layers (high-density fat at the bottom and low-density fat on the top). The upper layer is directly emulsified by intersyringe shifting, at a rate of 20 mL/s for 6x to 8x. The emulsified fat is centrifuged at 2,000 x g for 3 min, and the sticky substance under the oil layer is collected and defined as the extracellular matrix (ECM)/SVF-gel. The oil on the top layer is collected. Approximately 5 mL of oil is added to 15 mL of high-density fat and emulsified by intersyringe shifting, at a rate of 20 mL/s for 6x to 8x. The emulsified fat is centrifuged at 2,000 x g for 3 min, and the sticky substance is also ECM/SVF-gel. After the transplantation of the ECM/SVF-gel into nude mice, the graft is harvested and assessed by histologic examination. The result shows that this product has the potential to regenerate into normal adipose tissue. This procedure is a simple, effective mechanical dissociation procedure to condense the SVF cells embedded in their natural supportive ECM for regenerative purposes.

Giant myelolipomas and inadvertent bilateral adrenalectomy in classic congenital adrenal hyperplasia.

SummaryMyelolipomas have been reported in patients with congenital adrenal hyperplasia (CAH). ACTH excess, as seen with non-adherence to glucocorticoid therapy, may be responsible for tumor development. We report a case of a 51-year-old man with classic salt-wasting CAH managed on prednisone 7.5 mg daily and fludrocortisone who presented with chronic back pain and was found to have giant bilateral retroperitoneal masses. On computed tomography (CT) imaging, the masses were heterogeneous, but contained predominantly low-density fat attenuation. The tumors were resected due to concern for malignancy and mass symptoms. Pathologic examination identified both retroperitoneal masses as myelolipomas. The left tumor was 34×20×13 cm and weighed 4.7 kg and the right tumor was 20 cm in the largest dimension. Adrenal tissue was present in the specimen. The patient reported long-term compliance with glucocorticoid treatment. However, no biochemical monitoring of ACTH levels had occurred. Therefore, it is unclear if ACTH excess contributed to the development of these large tumors in this patient. It was presumed that both adrenal glands were inadvertently removed during surgery and the patient was treated with physiologic replacement doses of hydrocortisone and fludrocortisone postoperatively. In this case, the bilateral adrenalectomy was inadvertent. However, adrenalectomy can be considered as a treatment option in patients with classical CAH under certain circumstances to avoid complications of glucocorticoid excess.Learning pointsMyelolipomas should be considered in the differential diagnosis of adrenal or retroperitoneal masses in patients with CAH.On CT imaging, myelolipomas are seen as heterogeneous masses with low-density mature fat interspersed with more dense myeloid tissue.Myelolipomas are usually unilateral and measure <4 cm; however, very large and bilateral tumors have been reported.Treatment of CAH typically involves using supraphysiologic doses of glucocorticoid to suppress adrenal hyperandrogenism. Bilateral adrenalectomy is an alternative treatment option in patients with CAH.There is an association between ACTH excess and increased incidence of adrenal myelolipoma but the direct causal link remains to be established.

Endogenous Stem Cell Therapy Enhances Fat Graft Survival

Lipoaspirate centrifugation creates graded density of adipose tissue. High-density fat contains more vasculogenic cytokines and progenitor cells and has greater graft survival than low-density fat. The authors hypothesize that accelerating the bone marrow-derived progenitor cell response to injected low-density fat will improve its graft survival. Male 8-week-old FVB mice (n=60) were grafted with either high-density (n=20) or low-density (n=40) human lipoaspirate. Half of the mice receiving low-density fat (n=20) were treated with a stem cell mobilizer for 14 days. Grafted fat was harvested at 2 and 10 weeks for analysis. Low-density fat, low-density fat plus daily AMD3100, and high-density fat had 26±3.0, 61.2±7.5, and 49.6±3.5 percent graft survival, respectively, at 2 weeks (low-density fat versus low-density fat plus daily AMD3100 and low-density fat versus high-density fat, both p<0.01). Similar results were observed 10 weeks after grafting. Mice receiving low-density fat plus daily AMD3100 had significantly more vasculogenic progenitor cells per cubic centimeter of peripheral blood (p<0.01) and more new blood vessels (p<0.01). Both low-density fat plus daily AMD3100 and high-density fat contained more stromal-derived factor-1α and vascular endothelial growth factor mRNA/protein. Endogenous progenitor cell mobilization enhances low-density fat neovascularization, increases vasculogenic cytokine expression, and improves graft survival to a level equal to that of high-density fat grafts.

Marginal-Zone Lymphoma Mimicking Adrenal Myelolipoma on Computed Tomography Scan

A 69-yr-old woman was referred for a left adrenal mass incidentally discovered at computed tomography (CT) scan that was performed for abdominal pain. Clinical examination showed no signs of corticosteroid or catecholamine excess, and hormone assays revealed no abnormality. At CT scan, the lesion appeared as a 6-cm heterogeneous mass containing low-density fat surrounded by dense tissue (Fig. 1A). The neoplasm was associated with infiltration of the left perirenal fascia evocative of an inflammatory process (Fig. 1B). The diagnosis of adrenal myelolipoma complicated by extracapsular hemorrhage was suggested (1), and surgical removal of the lesion was performed through retroperitoneoscopy. Pathology showed no adrenal neoplasm but revealed an invasion of the periadrenal fat tissue by proliferation of monomorphic small lymphocytes (Fig. 1, C and D, and Fig. 2A). Immunolabeling of the tissue (Fig. 2, B and C) allowed establishing the diagnosis of marginal-zone B-cell lymphoma (MZL). Staging procedures showed involvement of spleen and bone marrow. Considering the good prognosis of MZL, therapeutic abstention was decided. Non-Hodgkin’s adrenal lymphomas are usually diffuse extranodal large B-cell lymphomas with poor prognosis. When bilateral, destruction of the adrenals by the proliferative lymphocytic process frequently results in adrenal insufficiency (2). Very rarely, lymphomas of the adrenal areas belong to the MZL subtype, also called small B-cell lymphoma (2, 3). MZLs arise from a marginal-zone B cell present in lymph nodes and extranodal tissues and are considered as indolent malignancies (3). In the patient’s case, invasion of periadrenal fat tissue by lymphocytic proliferation mimicked the appearance of adrenal myelolipoma on CT scan, i.e. a heterogeneous mass with mature fat intermingled with dense myeloid tissue (4).

Pathology Quiz Case 1

A 38-YEAR-OLD MAN PRESENTED WITH A 3-month history of a painless, slowgrowing mass of the left parotid gland, without any inflammatory cutaneous signs or facial weakness. He had no history of smoking or alcohol use. Physical examination revealed a 4.0 3.5-cm nontender, soft, mobile mass in the preauricular region of the left parotid gland. There was no evidence of adhesion to the overlying skin or palpable lymph nodes. Facial mobility was normal. The findings of cervical ultrasonography supported a diagnosis of hemangioma. A computed tomographic scan with contrast showed a 3.8 3.2 2.2-cm well-circumscribed parotid mass of the left superficial lobe, with intense, nearly homogeneous enhancement (Figure 1) and only a small focus of low-density fat in the deep portion of the tumor. Magnetic resonance imaging with gadolinium demonstrated a heterogeneous mass with massive enhancement, consistent with a vascular tumor of the superficial parotid lobe. A fine-needle biopsy specimen showed oncocytic cells exclusively (Figure 2). The patient underwent a left total parotidectomy with preservation of the facial nerve after the mass was located in the deep lobe of the gland. The definitive specimen is shown with regular staining in Figure 3 and with phosphotungstic acid–hematoxylin staining in Figure 4. What is your diagnosis?

A preparation of C14-labeled triglyceride in plasma as a tracer form plasma particulate fat.

SummaryA method is described for dispersing C14-labeled triglyceride in plasma to form low density fat particles which are similar in size, flotation and electrophoretic mobility to the particulate fat present in plasma during fat absorption. The removal rate in man of a trace dose (less than 1 mg) of this preparation of radioactive particulate fat is rapid. Small loads (2 g) of unlabeled lymph or emulsified fat given simultaneously significantly prolong the removal rate. This rate is comparable to that observed after administration of a similar load of labeled human chylomicrons.