Acalculous variant of Mirizzi syndrome: Imaging and clinical characteristics.

PURPOSE: Mirizzi Syndrome is a rare disease that causes biliary obstruction in the setting of an impacted stone in the gallbladder neck or Hartmann's Pouch which exerts mass effect on the common duct; however, we have noticed inflammatory biliary narrowing in the absence of an offending gallstone in the setting of acute cholecystitis. The purpose of this study is to report the clinical and MRCP findings in a series of 10 patients with this variant of Mirizzi Syndrome. MATERIALS AND METHODS: A search of our institution's PACS and electronic medical record identified 10 patients with a diagnosis of acute cholecystitis and narrowing of the common duct on imaging in the absence of an impacted gallstone. Imaging and clinical findings were confirmed by two board-certified abdominal radiologists. RESULTS: All patients presented with abdominal pain and an average elevated total bilirubin of 3.0 mg/dL. Seven patients had MRCP findings of complete narrowing of the CBD. Nine patients had intrahepatic biliary ductal dilation. All nine patients with gadoliniumenhanced MRCP displayed biliary wall thickening with enhancement adjacent to the gallbladder. Nine patients underwent cholecystectomy, one patient underwent percutaneous cholecystostomy. Average bilirubin upon discharge was within normal limits at 0.9 mg/dL after intervention. Two patients had follow-up MRCP showing resolution of biliary narrowing. CONCLUSION: A variant of Mirizzi Syndrome occurs in the absence of an offending gallstone in the gallbladder neck or cystic duct to explain the biliary narrowing. We postulate that acute cholecystitis can cause a local inflammatory narrowing resulting in biliary obstruction.

A Mixed-Surface Polyamidoamine Dendrimer for In Vitro and In Vivo Delivery of Large Plasmids.

Drug delivery to the brain is highly hindered by the presence of the blood-brain barrier (BBB), which prevents the entry of many potential drugs/biomolecules into the brain. One of the current strategies to achieve gene therapy for neurodegenerative diseases involves direct injection of a viral vector into the brain. There are various disadvantages of viral vectors, including limitations of cargo size and safety concerns. Nanomolecules, such as dendrimers, serve as an excellent alternative to viral delivery. In this study, as proof-of-concept, we used a surface-modified dendrimer complex and delivered large plasmids to cells in vitro and in vivo in healthy rats via intracranial injection. The dendrimers were biodegradable by chemicals found within cells and toxicity assays revealed that the modified dendrimers were much less toxic than unmodified amine-surface dendrimers. As mentioned in our previous publication, these dendrimers with appropriately modified surfaces are safe, can deliver large plasmids to the brain, and can overcome the cargo size limitations associated with viral vectors. The biocompatibility of this dendritic nanomolecule and the ability to finely tune its surface chemistry provides a gene delivery system that could facilitate future in vivo cellular reprograming and other gene therapies.

Imaging evaluation of COVID-19 in the emergency department.

PURPOSE: The purpose of this study is to elucidate the chest imaging findings of suspected COVID-19 patients presenting to the emergency department and the relationship with their demographics and RT-PCR testing results. METHODS: Patients presenting to the ED between March 12 and March 28, 2020, with symptoms suspicious for COVID-19 and subsequent CXR and/or CT exam were selected. Patients imaged for other reasons with findings suspicious for COVID-19 were also included. Demographics, laboratory test results, and history were extracted from the medical record. Descriptive statistics were used to explore the relationship between imaging and these factors. RESULTS: A total of 227 patients from the emergency department were analyzed (224 CXRs and 25 CTs). Of the 192 patients with COVID-19 results, 173 (90.1%) had COVID-19 RT-PCR (+). Abnormal imaging (CXR, 85.7% and/or CT, 100%) was noted in 155 (89.6%) of COVID-19 RT-PCR (+) cases. The most common imaging findings were mixed airspace/interstitial opacities (39.8%) on CXR and peripheral GGOs on CT (92%). The most common demographic were African Americans (76.8%). Furthermore, 97.1% of African Americans were RT-PCR (+) compared to 65.8% of Caucasians. CONCLUSION: We found a similar spectrum of thoracic imaging findings in COVID-19 patients as previous studies. The most common demographic were African Americans (76.8%). Furthermore, 97.1% of African Americans were RT-PCR (+) compared to 65.8% of Caucasians. Both CT and CXR can accurately identify COVID-19 pneumonitis in 89.6% of RT-PCR (+) cases, 89.5% of false negatives, and 72.7% of cases with no RT-PCR result.

Use of Polyamidoamine Dendrimers in Brain Diseases.

Polyamidoamine (PAMAM) dendrimers are one of the smallest and most precise nanomolecules available today, which have promising applications for the treatment of brain diseases. Each aspect of the dendrimer (core, size or generation, size of cavities, and surface functional groups) can be precisely modulated to yield a variety of nanocarriers for delivery of drugs and genes to brain cells in vitro or in vivo. Two of the most important criteria to consider when using PAMAM dendrimers for neuroscience applications is their safety profile and their potential to be prepared in a reproducible manner. Based on these criteria, features of PAMAM dendrimers are described to help the neuroscience researcher to judiciously choose the right type of dendrimer and the appropriate method for loading the drug to form a safe and effective delivery system to the brain.