Organizer-Like Reticular Stromal Cell Layer Common to Adult Secondary Lymphoid Organs

Abstract Mesenchymal stromal cells are crucial components of secondary lymphoid organs (SLOs). Organogenesis of SLOs involves specialized stromal cells, designated lymphoid tissue organizer (LTo) in the embryonic anlagen; in the adult, several distinct stromal lineages construct elaborate tissue architecture and regulate lymphocyte compartmentalization. The relationship between the LTo and adult stromal cells, however, remains unclear, as does the precise number of stromal cell types that constitute mature SLOs are unclear. From mouse lymph nodes, we established a VCAM-1+ICAM-1+MAdCAM-1+ reticular cell line that can produce CXCL13 upon LTβR stimulation and support primary B cell adhesion and migration in vitro. A similar stromal population sharing many characteristics with the LTo, designated marginal reticular cells (MRCs), was found in the outer follicular region immediately underneath the subcapsular sinus of lymph nodes. Moreover, MRCs were commonly observed at particular sites in various SLOs even in Rag2−/− mice, but were not found in ectopic lymphoid tissues, suggesting that MRCs are a developmentally determined element. These findings lead to a comprehensive view of the stromal composition and architecture of SLOs

Studies on the Tissue Mast Cells in the Liver 2. Observations on the Tissue Mast Cells in the Experimental Damaged Liver

In the preceding report, the author studied the changes of tissue mast cells (TMC) in the specimens of liver biopsy specimens of viral hepatitis. The present study was attempted to confirm, by animal experiments, the data described in the previous report. Animals used were male dogs, mice and rabbits. Chloroform and carbon tetrachloride were administrated for experimental damage of the liver tissue. The experiments gave the following results: 1. TMC were found both in intralobular and periportal region of the liver. Destructive processes such as dispersion, degranulation, destruction and condensation of the granule in TMC were found in an early stage of the liver damage. A marked increase in number and morphological changes of TMC as the remarkable proliferation of the connective tissue in periportal and intralobular regions were noted in such chronic stage. 2. A marked decrease in number and remarkable morphological changes of TMC were observed in the cases on an adrenocorticosteroid hormon therapy. 3. TMC were chiefly found in the periportal region of rat's liver, and a increase in number and morphological changes were found when the connective tissue increased in the periportal field after long-term administration of hepato-toxic drugs. 4. The asministration of the adrenal cortical hormones induced a marked decrease in number and destractive and condensed chages of TMC granules at this stage. 5. Administrations of the remedies for liver damage such as glucronic acid, thioctic acid, multi-vitamines and communin induced a slight increase in mumber and slight changes in the morphological findings comparing with control groups. The only remarkable change were the condensation of TMC granules. 6. Only a few TMC were found in rabbit's liver, and there were minimal or no changes in TMC, even in the stage of marked damage of the liver tissue. 7. These results lead to the following conculsions: There is a close relation between the proliferation of the connective tissue in dog's and rat's liver and the changes of TMC

Surveillance of Extended-Spectrum β-Lactamase-producing Carriage in a Japanese Intensive Care Unit: a Retrospective Analysis

Background The effectiveness of surveillance to identify extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-E) carriers is controversial during a non-outbreak situation. We performed additional stool cultures for ESBL-E among intensive care unit (ICU) patients already under active surveillance by means of sputum and urine cultures. We aimed to assess the efficacy of stool cultures for screening for ESBL-E in a non-outbreak situation. Methods We conducted a retrospective cohort study in an ICU. Sputum and urine samples were cultured for ESBL-E surveillance purposes from January to September 2013 (phase 1). Stool cultures were routinely performed in addition from January to September 2014 (phase 2). Antimicrobial use density values and clinical outcomes were investigated and compared between phase 1 and 2. Results We identified 512 and 478 patients in phase 1 and phase 2, respectively. ESBL-E were found in the feces of 65 (13.6%) patients in phase 2. The antimicrobial use density values (expressed as defined daily doses per 1,000 bed-days) were not significantly different between the two phases for fluoroquinolones (7 vs. 10, p = 0.376), third-generation cephalosporins (24.2 vs. 29.5, p = 0.724), tazobactam/ piperacillin (44.6 vs. 57.3, p = 0.489), and carbapenems (73 vs. 55.5, p = 0.222). Moreover, there were no significant differences in ICU mortality and length of stay (11.5% vs. 9.8%, p = 0.412, and 9 vs. 10 days, p = 0.28, respectively). Conclusions Stool culture seemed ineffective in improving the antimicrobial use density of broad-spectrum antimicrobials, clinical outcomes, and ICU length of stay, and is not recommended for surveillance of ESBL-E in a non-outbreak situation

Multiple mutations of Mycobacterium intracellulare subsp. chimaera causing false-negative reaction to the transcription-reverse transcription concerted method for pathogen detection

Objectives: To report an isolate of Mycobacterium intracellulare subsp. chimaera with multiple mutations in 16S ribosomal RNA (rRNA) gene, resulting in the false-negative reaction to the transcription-reverse transcription concerted (TRC) method for Mycobacterium avium-intracellulare complex. Methods: We used TRC, polymerase chain reaction (PCR), and Matrix-assisted laser desorption/ionization Time-of-Flight/Mass Spectrometry (MALDI-TOF/MS) methods to identify a clinical isolate in 2021. Due to the discordant results between TRC and PCR or MALDI-TOF MS methods, 16S rRNA sequencing, whole-genome shotgun (WGS) sequencing, and average nucleotide identity (ANI) analysis were employed to identify the isolate. Results: A mycobacterial isolate from a sputum sample gave negative results for the detection of Mycobacterium tuberculosis complex or M. avium-intracellulare complex by the TRC method. However, the isolate was identified as M. intracellulare by both PCR method and MALDI-TOF MS method. WGS sequencing of 16S rRNA genome revealed eight substitution mutations and one insertion mutation within the region, which could hamper the correct reaction to TRC method. Subsequent ANI analysis between the isolate and various species of nontuberculosis mycobacteria revealed that the isolate could be identified as M. intracellulare subsp. chimaera. Conclusion: Rare mutations within the 16S rRNA genome resulted in the false-negative identification of Mycobacterium chimaera by the TRC method. WGS sequencing and ANI analysis was necessary to identify the isolate