A Preliminary Look at the Macrovascular System for Transmetatarsal Amputation Success.

OBJECTIVE: Transmetatarsal amputation (TMA) is a commonly used level of amputation that preserves most of the foot's function and independence. However, many TMAs fail, and patients go onto higher amputations. The primary endpoint of this study is to determine if source artery occlusions are correlated with TMA flap failure. METHODS: A total of 82 patients with TMAs were retrospectively reviewed for healing rates between 2009 and 2019 at a single center. Forty-five of the patients had an angiogram, which was analyzed for source artery and overall TMA failure. Of the initial 82 patients, a cohort of 12 had documentation of specific flap failure and an angiogram performed. This cohort of 12 patients was used for correlation of flap failure with source artery occlusion. RESULTS: Overall, the TMA healing rate was 45.28%. No correlation was noted between a specific source artery occlusion and overall TMA failure. However, a moderate positive correlation was seen with dorsalis pedis artery and peroneal artery occlusions and dorsal flap failure. No correlation was seen with the posterior tibial artery and plantar flap failure. A moderate negative correlation was seen with peroneal artery occlusion and plantar flap failure. CONCLUSIONS: The authors concluded that retrograde flow through the angiosome principle is what allowed for successful outcomes in TMAs. Physicians are urged to carefully plan, dissect, and preserve these vessels to help prevent TMA flap failure, especially in patients with vascular risk or disease.

Regulation of Insulin Clearance by Non-Esterified Fatty Acids.

Insulin stores lipid in adipocytes and prevents lipolysis and the release of non-esterified fatty acids (NEFA). Excessive release of NEFA during sustained energy supply and increase in abdominal adiposity trigger systemic insulin resistance, including in the liver, a major site of insulin clearance. This causes a reduction in insulin clearance as a compensatory mechanism to insulin resistance in obesity. On the other hand, reduced insulin clearance in the liver can cause chronic hyperinsulinemia, followed by downregulation of insulin receptor and insulin resistance. Delineating the cause-effect relationship between reduced insulin clearance and insulin resistance has been complicated by the fact that insulin action and clearance are mechanistically linked to insulin binding to its receptors. This review discusses how NEFA mobilization contributes to the reciprocal relationship between insulin resistance and reduced hepatic insulin clearance, and how this may be implicated in the pathogenesis of non-alcoholic fatty liver disease.

As We Drink and Breathe: Adverse Health Effects of Microcystins and Other Harmful Algal Bloom Toxins in the Liver, Gut, Lungs and Beyond.

Freshwater harmful algal blooms (HABs) are increasing in number and severity worldwide. These HABs are chiefly composed of one or more species of cyanobacteria, also known as blue-green algae, such as Microcystis and Anabaena. Numerous HAB cyanobacterial species produce toxins (e.g., microcystin and anatoxin-collectively referred to as HAB toxins) that disrupt ecosystems, impact water and air quality, and deter recreation because they are harmful to both human and animal health. Exposure to these toxins can occur through ingestion, inhalation, or skin contact. Acute health effects of HAB toxins have been well documented and include symptoms such as nausea, vomiting, abdominal pain and diarrhea, headache, fever, and skin rashes. While these adverse effects typically increase with amount, duration, and frequency of exposure, susceptibility to HAB toxins may also be increased by the presence of comorbidities. The emerging science on potential long-term or chronic effects of HAB toxins with a particular emphasis on microcystins, especially in vulnerable populations such as those with pre-existing liver or gastrointestinal disease, is summarized herein. This review suggests additional research is needed to define at-risk populations who may be helped by preventative measures. Furthermore, studies are required to develop a mechanistic understanding of chronic, low-dose exposure to HAB toxins so that appropriate preventative, diagnostic, and therapeutic strategies can be created in a targeted fashion.

Loss of Hepatic Carcinoembryonic Antigen-Related Cell Adhesion Molecule 1 Links Nonalcoholic Steatohepatitis to Atherosclerosis.

Patients with nonalcoholic fatty liver disease/steatohepatitis (NAFLD/NASH) commonly develop atherosclerosis through a mechanism that is not well delineated. These diseases are associated with steatosis, inflammation, oxidative stress, and fibrosis. The role of insulin resistance in their pathogenesis remains controversial. Albumin (Alb)Cre+ Cc1flox ( fl ) /fl mice with the liver-specific null deletion of the carcinoembryonic antigen-related cell adhesion molecule 1 (Ceacam1; alias Cc1) gene display hyperinsulinemia resulting from impaired insulin clearance followed by hepatic insulin resistance, elevated de novo lipogenesis, and ultimately visceral obesity and systemic insulin resistance. We therefore tested whether this mutation causes NAFLD/NASH and atherosclerosis. To this end, mice were propagated on a low-density lipoprotein receptor (Ldlr) -/- background and at 4 months of age were fed a high-cholesterol diet for 2 months. We then assessed the biochemical and histopathologic changes in liver and aortae. Ldlr-/-AlbCre+Cc1fl/fl mice developed chronic hyperinsulinemia with proatherogenic hypercholesterolemia, a robust proinflammatory state associated with visceral obesity, elevated oxidative stress (reduced NO production), and an increase in plasma and tissue endothelin-1 levels. In parallel, they developed NASH (steatohepatitis, apoptosis, and fibrosis) and atherosclerotic plaque lesions. Mechanistically, hyperinsulinemia caused down-regulation of the insulin receptor followed by inactivation of the insulin receptor substrate 1-protein kinase B-endothelial NO synthase pathway in aortae, lowering the NO level. This also limited CEACAM1 phosphorylation and its sequestration of Shc-transforming protein (Shc), activating the Shc-mitogen-activated protein kinase-nuclear factor kappa B pathway and stimulating endothelin-1 production. Thus, in the presence of proatherogenic dyslipidemia, hyperinsulinemia and hepatic insulin resistance driven by liver-specific deletion of Ceacam1 caused metabolic and vascular alterations reminiscent of NASH and atherosclerosis. Conclusion: Altered CEACAM1-dependent hepatic insulin clearance pathways constitute a molecular link between NASH and atherosclerosis.