Plant cell walls are comprised largely of the polysaccharides cellulose, hemicellulose, and pectin, along with ;10% protein and up to 40% lignin. These wall polymers interact covalently and noncovalently to form the functional cell wall. Characterized cross-links in the wall include covalent linkages between wall glycoprotein extensins between rhamnogalacturonan II monomer domains and between polysaccharides and lignin phenolic residues. Here, we show that two isoforms of a purified Arabidopsis thaliana arabinogalactan protein (AGP) encoded by hydroxyproline-rich glycoprotein family protein gene At3g45230 are covalently attached to wall matrix hemicellulosic and pectic polysaccharides, with rhamnogalacturonan I (RG I)/homogalacturonan linked to the rhamnosyl residue in the arabinogalactan (AG) of the AGP and with arabinoxylan attached to either a rhamnosyl residue in the RG I domain or directly to an arabinosyl residue in the AG glycan domain. The existence of this wall structure, named ARABINOXYLAN PECTIN ARABINOGALACTAN PROTEIN1 (APAP1), is contrary to prevailing cell wall models that depict separate protein, pectin, and hemicellulose polysaccharide networks. The modified sugar composition and increased extractability of pectin and xylan immunoreactive epitopes in apap1 mutant aerial biomass support a role for the APAP1 proteoglycan in plant wall architecture and function.

A 58-year-old male with a history of hypertension and non-insulin dependent type 2 diabetes mellitus (DM) was brought in by ambulance and admitted to the intensive care unit for weakness, lethargy, and altered mental status and was found to be hypotensive and subsequently diagnosed with severe diabetic ketoacidosis (DKA). A thorough investigation into precipitating factors for his DKA was largely unrevealing; an extensive infectious work- up was negative and the patient’s history was otherwise only significant for starting a ketogenic diet 1 month prior while simultaneously being on a sodium-glucose transport protein 2 (SGLT-2) inhibitor, namely empagliflozin. Literature investigation revealed that a strict low carbohydrate diet can rarely lead to DKA in the setting of SLGT-2 inhibitor use.

Background Clostridium difficile (C. difficile) is a common cause of infectious colitis in individuals with prior antibiotic or hospital exposure. Extraintestinal manifestations of C. difficile infections, however, are rare. Here we present a case of C. difficile appendicitis in an immunocompromised patient. Case presentation A 53-year-old Caucasian male presented to the emergency room for two days of lower abdominal pain associated with nausea and subjective fevers. He otherwise denied having diarrhea or hematochezia. He did not have any recent hospitalizations, nursing home stays, or antibiotic exposure. His past medical history was notable for stage III tonsillar squamous cell carcinoma for which he was status post tonsillectomy, radiation therapy, and chemotherapy (cisplatin 4 days prior to presentation). He was afebrile with tenderness to palpation in the bilateral lower quadrants, right greater than left. His white blood cell (WBC) count was 15.6 × 103 cells/μL. Computed tomography (CT) of the abdomen and pelvis showed marked edema and inflammation of the cecum and ascending colon as well as an enlarged appendix with surrounding inflammatory changes with a small amount of free fluid in the right paracolic gutter. He was treated non-surgically with antibiotics. He did not clinically improve and on hospital day 3, he developed diarrhea for which C. difficile stool polymerase chain reaction was sent. Repeat CT of the abdomen and pelvis was performed which showed progression to pan-colitis and persistent appendicitis. C. difficile testing later resulted positive, for which oral vancomycin was started. The patient markedly improved with medical management alone and was subsequently discharged on oral vancomycin. Conclusions Our case highlights the importance of maintaining a high index of suspicion for C. difficile in a patient presenting with both appendicitis and colitis, with prompt diagnosis and treatment being essential.

GUIDELINE TITLE: American Society of Hematology 2020 Guidelines for Sickle Cell Disease: Management of Acute and Chronic Pain RELEASE DATE: June 19, 2020 PRIOR VERSION: Not applicable DEVELOPER: American Society of Hematology Guideline Panel on Sickle Cell Disease-Related Pain FUNDING SOURCE: American Society of Hematology TARGET POPULATION: Adult and pediatric patients with a history of sickle cell disease with acute and chronic pain.