Masticator space abscess in a 47-day-old infant

A 47-day-old male infant presented with fever, poor oral intake, irritability, and right-sided bluish buccal swelling. Contrast-enhanced computed tomography of the neck showed a round mass lesion of about 2.0×1.5 cm that suggested abscess formation in the right masticator space. Ultrasound-guided extraoral aspiration of the abscess at the right masseter muscle was successful. Staphylococcus aureus was identified in the culture from the aspirated pus and blood. Appropriate antibiotics were given and the patient recovered. The patient underwent follow-up ultrasonography that showed an improved state of the previously observed right masseter muscle swelling at about 1 month after hospital discharge. A masticator space abscess usually originates from an odontogenic infection in adults. We report a case of masticator space abscess in a 47-day-old infant in whom septicemia without odontogenic infection was suspected

Teleological role of L-2-hydroxyglutarate dehydrogenase in the kidney

L-2-hydroxyglutarate (L-2HG) is an oncometabolite found elevated in renal tumors. However, this molecule might have physiological roles that extend beyond its association with cancer, as L-2HG levels are elevated in response to hypoxia and during Drosophila larval development. L-2HG is known to be metabolized by L-2HG dehydrogenase (L2HGDH), and loss of L2HGDH leads to elevated L-2HG levels. Despite L2HGDH being highly expressed in the kidney, its role in renal metabolism has not been explored. Here, we report our findings utilizing a novel CRISPR/Cas9 murine knockout model, with a specific focus on the role of L2HGDH in the kidney. Histologically, L2hgdh knockout kidneys have no demonstrable histologic abnormalities. However, GC-MS metabolomics demonstrates significantly reduced levels of the TCA cycle intermediate succinate in multiple tissues. Isotope labeling studies with [U-13C] glucose demonstrate that restoration of L2HGDH in renal cancer cells (which lowers L-2HG) leads to enhanced incorporation of label into TCA cycle intermediates. Subsequent biochemical studies demonstrate that L-2HG can inhibit the TCA cycle enzyme α-ketoglutarate dehydrogenase. Bioinformatic analysis of mRNA expression data from renal tumors demonstrates that L2HGDH is co-expressed with genes encoding TCA cycle enzymes as well as the gene encoding the transcription factor PGC-1α, which is known to regulate mitochondrial metabolism. Restoration of PGC-1α in renal tumor cells results in increased L2HGDH expression with a concomitant reduction in L-2HG levels. Collectively, our analyses provide new insight into the physiological role of L2HGDH as well as mechanisms that promote L-2HG accumulation in disease states