Acoustic radiation force impulse imaging of biopsy-proven Kikuchi disease: initial experiences for evaluating feasibility in pediatric patients

Purpose This study evaluated the feasibility of acoustic radiation force impulse (ARFI) elastography and characterized the sonographic features of lymph nodes (LNs) with Kikuchi disease in pediatric patients. Methods Seventy-six cervical LN biopsies were performed for the diagnosis of cervical lymphadenopathy. ARFI imaging was performed, and the characteristic ultrasound features of the biopsied LNs and the contralateral LNs were analyzed. We also reviewed clinical and conventional ultrasonographic findings. Results On histology, 56 patients were diagnosed with Kikuchi disease. These LNs were large and elongated, with increased perinodal echogenicity and capsular thickening. In 38 of them, ARFI elastography was performed, and the median shear wave velocity (SWV) of the biopsied LNs with Kikuchi disease (2.19 m/sec; range, 1.45 to 4.57 m/sec) was higher than of the contralateral LNs (1.72 m/sec; range, 0.95 to 2.65 m/sec; P<0.001). In patients with reactive hyperplasia, the mean SWV of the biopsied LNs (2.00 m/sec; range, 1.49 to 2.26 m/sec) was higher than that of the contralateral LNs (1.55 m/sec; range, 1.21 to 2.32 m/sec; P=0.031). Conclusion The SWV of LNs with Kikuchi disease was significantly higher than that of the contralateral LNs. Morphologically, LNs with Kikuchi disease showed an enlarged, elongated, and oval shape, increased perinodal echogenicity, and capsular thickening. In addition to the conventional ultrasonographic findings, the application of ARFI is feasible even in pediatric patients for the evaluation of cervical lymphadenopathy

In Vitro Amplification of Misfolded Prion Protein Using Lysate of Cultured Cells

Protein misfolding cyclic amplification (PMCA) recapitulates the prion protein (PrP) conversion process under cell-free conditions. PMCA was initially established with brain material and then with further simplified constituents such as partially purified and recombinant PrP. However, availability of brain material from some species or brain material from animals with certain mutations or polymorphisms within the PrP gene is often limited. Moreover, preparation of native PrP from mammalian cells and tissues, as well as recombinant PrP from bacterial cells, involves time-consuming purification steps. To establish a convenient and versatile PMCA procedure unrestricted to the availability of substrate sources, we attempted to conduct PMCA with the lysate of cells that express cellular PrP (PrPC). PrPSc was efficiently amplified with lysate of rabbit kidney epithelial RK13 cells stably transfected with the mouse or Syrian hamster PrP gene. Furthermore, PMCA was also successful with lysate of other established cell lines of neuronal or non-neuronal origins. Together with the data showing that the abundance of PrPC in cell lysate was a critical factor to drive efficient PrPSc amplification, our results demonstrate that cell lysate in which PrPC is present abundantly serves as an excellent substrate source for PMCA

Detecting mpox infection in the early epidemic: an epidemiologic investigation of the third and fourth cases in Korea

OBJECTIVES As few mpox cases have been reported in Korea, we aimed to identify the characteristics of mpox infection by describing our epidemiologic investigation of a woman patient (index patient, the third case in Korea) and a physician who was infected by a needlestick injury (the fourth case). METHODS We conducted contact tracing and exposure risk evaluation through interviews with these 2 patients and their physicians and contacts, as well as field investigations at each facility visited by the patients during their symptomatic periods. We then classified contacts into 3 levels according to their exposure risk and managed them to minimize further transmission by recommending quarantine and vaccination for post-exposure prophylaxis and monitoring their symptoms. RESULTS The index patient had sexual contact with a man foreigner during a trip to Dubai, which was considered the probable route of transmission. In total, 27 healthcare-associated contacts across 7 healthcare facilities and 9 community contacts were identified. These contacts were classified into high (7 contacts), medium (9 contacts), and low (20 contacts) exposure risk groups. One high-risk contact was identified as a secondary patient: a physician who was injured while collecting specimens from the index patient. CONCLUSIONS The index patient visited several medical facilities due to progressive symptoms prior to isolation. Although the 2022 mpox epidemic mainly affected young men, especially men who have sex with men, physicians should also consider mpox transmission in the general population for the timely detection of mpox-infected patients

PMCA using lysates of a wide range of cell types.

<p>Cell lysate of neuronal (N2a), prion-free brain mesenchymal (SMB-PS), mixed cerebellar neuronal and glial (CRBL) or fibroblast (NIH 3T3) cells was concentrated to include the PrP^C level of wild brain homogenate. PMCA was performed by seeding with RML-sick (RML) and normal (NBH) brain homogenate. The seed dilution fold was 100–24,000. The PrP^Sc level of PMCA before (−) and after (+) was compared. Monoclonal anti-PrP 6H4 antibody was used for Western blotting.</p

PMCA using cell lysate of RK13SHaPrP.

<p>(A) PK-resistant PrP^Sc amplification of two Syrian hamster-adapted TME prions (HY and DY) with cell lysate (CL) of RK13SHaPrP. The HY and DY seeds were diluted 100–2,500 fold for PMCA. The level of PrP^Sc in pre- (−) and post-PMCA (+) samples was analyzed by Western blotting. (B) Comparison of the PK-resistant PrP^Sc of HY and DY prions generated by PMCA. The HY and DY seeds were diluted 100–62,500 fold for PMCA. Ten % brain homogenate (BH) of HY- and DY-sick Syrian hamsters were used as controls. PrP^Sc in both panels A and B was detected by monoclonal anti-PrP 3F4 antibody.</p

PrP^Sc amplification affected by PrP^C abundance in cell lysate.

<p>PMCA was performed using undiluted and diluted (1∶10 fold) RK13MoPrP cell lysate (CL). Both RML and NBH were used as seeds in dilutions of 100–24,000 fold. PK-treated pre- (−) and post-PMCA (+) samples were analyzed. Western blotting was performed using monoclonal anti-PrP 6H4 antibody.</p

Expression of PrP^C in a variety of cell lines.

<p>(A) Comparison of the PrP^C levels in cell lines and brain homogenate. Western blotting followed by densitometry demonstrated relative differences of the PrP^C levels. Extrapolation of multiplication factors to concentrate cell lysate was based on the amount of protein analyzed and the relative PrP^C levels. PrP^C was detected by D13 (left blot), 6H4 (middle blot), and 3F4 (right blot) antibodies. (B) Fluorescence images of RK13 cells expressing full length mouse PrP^C. Colocalization (yellow, overlay) of PrP^C (green) and GM1 (red) in the lipid rafts of the plasma membrane of RK13MoPrP was shown by confocal microscopy. The nuclei (blue) were stained by Hoechst 33258. Scale was shown by a 30 µm bar.</p