Computational Mechanisms of Osmoregulation: A Reinforcement Learning Model for Sodium Appetite.

Homeostatic control with oral nutrient intake is a vital complex system involving the orderly interactions between the external and internal senses, behavioral control, reward learning, and decision-making. Sodium appetite is a representative system and has been intensively investigated in animal models of homeostatic systems and oral nutrient intake. However, the system-level mechanisms for regulating sodium intake behavior and homeostatic control remain unclear. In the current study, we attempted to provide a mechanistic understanding of sodium appetite behavior by using a computational model, the homeostatic reinforcement learning model, in which homeostatic behaviors are interpreted as reinforcement learning processes. Through simulation experiments, we confirmed that our homeostatic reinforcement learning model successfully reproduced homeostatic behaviors by regulating sodium appetite. These behaviors include the approach and avoidance behaviors to sodium according to the internal states of individuals. In addition, based on the assumption that the sense of taste is a predictor of changes in the internal state, the homeostatic reinforcement learning model successfully reproduced the previous paradoxical observations of the intragastric infusion test, which cannot be explained by the classical drive reduction theory. Moreover, we extended the homeostatic reinforcement learning model to multimodal data, and successfully reproduced the behavioral tests in which water and sodium appetite were mediated by each other. Finally, through an experimental simulation of chemical manipulation in a specific neural population in the brain stem, we proposed a testable hypothesis for the function of neural circuits involving sodium appetite behavior. The study results support the idea that osmoregulation via sodium appetitive behavior can be understood as a reinforcement learning process, and provide a mechanistic explanation for the underlying neural mechanisms of decision-making related to sodium appetite and homeostatic behavior.

Eruption of a venous malformation through an iliac bone harvesting site after trauma.

Harvesting grafts from the anterior iliac bone has been associated with various complications. A 50-year-old woman presented to our department with a chief complaint of right inguinal swelling and pain. Autologous bone grafts had been harvested on two previous occasions from the right anterior iliac crest for use in the reconstruction of multiple facial fractures. Computed tomography and magnetic resonance imaging revealed a full-thickness bone defect in the right anterior iliac crest. A mass was noted in the right gluteus minimus, while a multilocular cystic mass extended from the right iliac crest defect to the right inguinal region. Both the inguinal mass and gluteal mass were removed under general anesthesia. Following histopathological analysis, the gluteal mass was diagnosed as a venous malformation(VM). Based on the patient's clinical course, iliac bone graft harvesting and trauma to the gluteal region triggered hemorrhaging from the VM. Blood components leaked out from the fragile portion of the iliac bone defect, forming a cystic lesion that developed into the inguinal mass. In this case, a coincidental VM resulted in a rare complication of iliac bone graft harvesting. These sequelae could have been avoided by planning for more appropriate ways to collect the grafts.

Halo-Type Distraction Device Used to Treat a Severe Midface Depression Fracture.

The deep layers of the nasoethmoid region comprise a thin-walled lacrimal bone, a paper-thin ethmoid plate, and ethmoidal cells, forming an extremely fragile and easily crushed structure. In a nasoethmoid complex fracture where the support structure itself is destroyed, epithesis and immobilization are difficult and can lead to residual saddle nose deformities. Therefore, bone grafts are often necessary at a later date. Recently, the authors occasionally see reports of nasoethmoid complex fractures that are treated with Halo distraction devices. Advantages of this device are that it applies constant traction to maintain the shape of the structures until the ruptured nasoethmoid bone and mucosa are repaired, thus minimizing relapse. There is no need for rigid fixation with a plate, no limitations on how much distraction is possible, and no major skin incisions are required for the approach. The authors treated a 30-year-old man who suffered a severe and widespread depressed facial deformation due to a nasoethmoid fracture that included a midface comminuted fracture using a Halo-type distraction device. A gentle traction was maintained on the nasoethmoid bone and part of the maxilla pulling it forward, and resulted in an extremely good outcome both esthetically and functionally. This method is believed to be extremely useful and effective, requiring only minimally invasive surgery for comminuted midface fractures involving a nasoethmoid fracture with a depressed frontal process of the maxilla. Below, the authors provide a detailed description of their experience with this device.

An anatomical study of the pathophysiology of carotid cavernous sinus fistula associated with Le Fort III osteotomy.

UNLABELLED: Carotid-cavernous sinus fistula (CCF) is a rare complication occurring after the Le Fort osteotomy. We aimed to elucidate the cause of CCF in the Le Fort osteotomy. METHODS: Eleven fresh cadavers were used. After craniotomy, a Le Fort III bipartition osteotomy was then performed. On the left side, both the lateral wall of the maxilla and the pterygomaxillary junction (PMJ) were divided, in addition to the conventional osteotomy line. On the right side, those parts were kept intact. After the osteotomy, a tensiometer was fixed to the skull base. The sensor was linked with the wall of the carotid artery in the cavernous portion. A down-fracture was then performed initially from the left, followed by the right. Tensile force data of both sides were recorded. RESULTS: In all cases, a higher tensile load was observed on the right side compared to the left side. In right side, two skull base fractures complexed with high pterygoid process fractures, and nine pure high fractures of the pterygoid process were identified. CONCLUSIONS: During down-fracture, the wall of the carotid artery experiences significant tensile load. The tensile load on the arterial wall may collapse the fine branches of the carotid artery in the cavernous portion.

The "stepped caudal exposure" technique for excision of nasal dermoids with intracranial extension.

Nasal dermoid sinus cysts (NDSCs) are rare congenital malformations derived from ectodermal and mesodermal tissues. There are numerous reports on surgical approaches for extirpation of NDSCs with intracranial extension. Here we describe the "stepped caudal exposure" approach, a technique that minimizes the risk for bacterial infection of the central nervous system from the nasal space. This procedure involves a stepwise osteotomy of the frontal and nasal bones that permits sufficient exposure to allow complete extirpation of NDSCs; it was used successfully to treat a 20-month-old boy with NDSC extending into the intracranial space and an infectious abscess. After NDSC extirpation and debridement of the abscess, the anterior skull base was reconstructed with bone grafts placed on both the intracranial and intranasal sides of the widened foramen cecum. Thereafter, each graft was covered by frontal pericranial flaps for blood supply. These modified surgical techniques may enhance the safety of surgical removal of NDSC, particularly in cases accompanied by infectious lesions such as abscesses.

Reconstruction of the great toe using a pedicled medial plantar flap with anterograde venous drainage.

BACKGROUND: Reconstruction of the great toe defect is difficult. The most distal point of the rotation arc of a retrograde-flow medial plantar flap is the plantar side of the proximal phalanx. The purpose of this report was to present a new procedure that extends the rotation arc of this flap. Results of anatomic study and application in two patients were presented. METHODS: An anatomical study was conducted on 10 freshly frozen cadavers to determine the rotation arc of the medial plantar flap based distally on the lateral plantar vessels. To enable anterograde venous drainage, two accompanying veins of the vascular pedicle were separated and anastomosed to each other. This surgical procedure was implemented in two clinical cases with the great toe defect. The maximum size of the elevated flap was 4 × 7 cm. The status of venous congestion of the flap was determined using the blood glucose measurement index. RESULTS: We confirmed that the rotation arc of the medial plantar flap based distally on the lateral plantar vessels could reach the tip of the great toe, preserving all lateral plantar nerves and plantar metatarsal arteries. In the two cases, the congestion of the flap improved with anterograde venous drainage and the flaps survived completely. CONCLUSION: A pedicled medial plantar flap with anterograde venous drainage may be a useful alternative option for the reconstruction of relatively large great toe defects.

Low-level mesodermal somatic mutation mosaicism: late-onset craniofacial and cervical spinal hyperostoses.

Craniofacial and cervical spinal hyperostoses are rarely seen in the absence of other abnormalities. Only seven patients with isolated cranial hyperostoses have been reported, and only a single patient with both calvarial and cervical vertebral hyperostoses. We report on an adult with late-onset right-sided asymmetrical hyperostoses of the cranium, mandible, and cervical vertebrae in the absence of an AKT1 mutation. At presentation, the patient displayed neither generalized overgrowth nor dysregulated adipose tissue. Standard polymerase chain reaction and Sanger sequencing of DNA extracted from formalin-fixed paraffin-embedded frontal bone and mandibular angular bone was negative for an AKT1 mutation. Though the patient's clinical manifestations did not fulfill the consensus diagnostic criteria of Proteus syndrome, the mosaic distribution of lesions, the sporadic occurrence, and the patient's progressive course were consistent with a somatic mosaicism similar to that syndrome. Hence, the patient's phenotype may have been caused by a very late mesodermal somatic mutation during embryogenesis.

Subjective global assessment is not sufficient to screen patients with defective hepatic metabolism.

BACKGROUND AND AIMS: Subjective global assessment (SGA) is useful for screening malnourished patients with several diseases, although it has been indicated to underestimate nutritional status for patients with liver disease. Accordingly, the aim of this study was to examine the usefulness of SGA as a nutritional screening tool for patients with liver disease, compared to patients with gastroenterological disease, without bias of personal ability and experience. METHODS: SGA was performed on 129 of hospitalized patients (86 with liver disease and 43 with gastroenterological disease). Nutritional status was categorized as well-nourished or malnourished status, based on nutritional indicators from laboratory data. RESULTS: The SGA screening ratio (sensitivity) for malnourished patients with liver disease was significantly lower than gastroenterological disease, while specificity or efficiency was not significantly different. In nutritional indicators from laboratory data, the difference between SGA-positive and SGA-negative patients with liver disease was significant but not so remarkable compared with the difference between those with other diseases. The positive number of SGA components per patient for the liver disease group was significantly less than gastroenterological disease group. CONCLUSIONS: SGA for patients with liver diseases was not sufficient as a nutritional screening tool because malnutrition induced by defective hepatic metabolism was not characterized fully.