Chylothorax caused by blunt trauma: Case review and management proposal.

Chylothorax is a potentially devastating complication of lymphatic trauma of the thorax. To date, no recommendations have provided decision making support for prompt definitive treatment. We present a 53 year old male involved in a motor vehicle collision sustaining 9 left rib fractures with flail segments. He was treated non-operatively with a chest tube and no fat diet. A Case report review was performed and a proposed guideline for managing blunt trauma chylothorax in adult patients was developed. In low-output chylothorax, effective initial treatment begins with a no fat diet and chest tube. We propose that a low output leak be defined as <500 mL of initial output or <500 mL/day and can be managed non-operatively in nearly 100% of patients. High output injuries of >1000 mL of initial output will require surgical intervention and should be considered for prompt definitive care.

Liver retinol transporter and receptor for serum retinol-binding protein (RBP4).

Vitamin A (retinol) is absorbed in the small intestine, stored in liver, and secreted into circulation bound to serum retinol-binding protein (RBP4). Circulating retinol may be taken up by extrahepatic tissues or recycled back to liver multiple times before it is finally metabolized or degraded. Liver exhibits high affinity binding sites for RBP4, but specific receptors have not been identified. The only known high affinity receptor for RBP4, Stra6, is not expressed in the liver. Here we report discovery of RBP4 receptor-2 (RBPR2), a novel retinol transporter expressed primarily in liver and intestine and induced in adipose tissue of obese mice. RBPR2 is structurally related to Stra6 and highly conserved in vertebrates, including humans. Expression of RBPR2 in cultured cells confers high affinity RBP4 binding and retinol transport, and RBPR2 knockdown reduces RBP4 binding/retinol transport. RBPR2 expression is suppressed by retinol and retinoic acid and correlates inversely with liver retinol stores in vivo. We conclude that RBPR2 is a novel retinol transporter that potentially regulates retinol homeostasis in liver and other tissues. In addition, expression of RBPR2 in liver and fat suggests a possible role in mediating established metabolic actions of RBP4 in those tissues.