We demonstrated a robust, inexpensive method for fabricating high-throughput gas gradient generation devices which combined classic mass-transfer limited techniques with the versatility of elastomer microfluidics. The method allowed for dozens of replicate mass-transfer gradient experiments per day, including fabrication and assembly of devices. We demonstrated how our devices can be interfaced with microfluidics and how gradient parameters can be varied. In this work, we applied the method to characterize gradients of pH and cell viability generated in mass-transfer limited cultures of HeLa cells and observed the morphology of differentiating C2Cl2 myoblasts in an oxygen gradient.

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Streptococcus gallolyticus subspecies (subsp.) gallolyticus (formerly bovis biotype I) bacteremia has been associated with colonic adenocarcinoma. The bovis species underwent reclassification in 2003. Subtypes of gallolyticus are associated with colonic malignancy but are less frequent, resulting in less awareness. A 71-year-old male admitted with worsening lower back pain and fevers. Initial vital signs and laboratory data were within normal limits. MRI revealed lumbosacral osteomyelitis and antibiotics were initiated. Blood cultures showed Streptococcus species, prompting a transesophageal echocardiogram (TEE) revealing vegetations on the mitral and aortic valves. The etiology for his endocarditis was unclear. A colonoscopy was suggested, but his clinical instability made such a procedure intolerable. Final cultures revealed Streptococcus gallolyticus subsp. pasteurianus (previously bovis biotype II). After antibiotic completion he underwent aortic grafting with valve replacements. Later, he was readmitted for Streptococcus bacteremia. After a negative TEE, colonoscopy revealed a 2.5 × 3 cm cecal tubulovillous adenoma with high-grade dysplasia suspicious for his origin of infection. Clinicians understand the link between Streptococcus gallolyticus subsp. gallolyticus (bovis type I) and malignancy, but the new speciation may be unfamiliar. There are no guidelines for managing S. gallolyticus subsp. pasteurianus bacteremia; therefore a colonoscopy should be considered when no source is identified.

Pyogenic liver abscesses (PLA) are an uncommon cause of hospitalization in the United States. The majority of such cases are polymicrobial and are most commonly caused by seeding of infection from the biliary system. PLA is frequently associated with specific comorbidities such as diabetes mellitus, history of liver transplant, underlying hepatobiliary, or pancreatic disease. Herein, we describe a 47-year-old healthy male with no known risk factors associated with PLA who presented to the hospital with acute fever, abdominal pain, and dark colored urine. Initially the patient had a negative right upper quadrant ultrasound. However, the patient continued to have persistent fevers and abnormal liver biochemistries with negative liver serology that led to checking a magnetic resonance cholangiopancreatography which suggested multiple liver abscesses. Computer tomography guided aspiration revealed a monobacterial Streptococcus species within the abscess, which is commonly associated with arterial bacteremia as a source of PLA. Arterial bacteremia is one of most rare causes of PLA. The patient's septic workup was negative for any source of infection. This case demonstrates a patient with no risk factors who was diagnosed with PLA caused by apparent arterial bacteremia with no clear source of infection.