X-ray structure and characterization of a probiotic Lactobacillus rhamnosus Probio-M9 L-rhamnose isomerase.

A recombinant L-rhamnose isomerase (L-RhI) from probiotic Lactobacillus rhamnosus Probio-M9 (L. rhamnosus Probio-M9) was expressed. L. rhamnosus Probio-M9 was isolated from human colostrum and identified as a probiotic lactic acid bacterium, which can grow using L-rhamnose. L-RhI is one of the enzymes involved in L-rhamnose metabolism and catalyzes the reversible isomerization between L-rhamnose and L-rhamnulose. Some L-RhIs were reported to catalyze isomerization not only between L-rhamnose and L-rhamnulose but also between D-allulose and D-allose, which are known as rare sugars. Those L-RhIs are attractive enzymes for rare sugar production and have the potential to be further improved by enzyme engineering; however, the known crystal structures of L-RhIs recognizing rare sugars are limited. In addition, the optimum pH levels of most reported L-RhIs are basic rather than neutral, and such a basic condition causes non-enzymatic aldose-ketose isomerization, resulting in unexpected by-products. Herein, we report the crystal structures of L. rhamnosus Probio-M9 L-RhI (LrL-RhI) in complexes with L-rhamnose, D-allulose, and D-allose, which show enzyme activity toward L-rhamnose, D-allulose, and D-allose in acidic conditions, though the activity toward D-allose was low. In the complex with L-rhamnose, L-rhamnopyranose was found in the catalytic site, showing favorable recognition for catalysis. In the complex with D-allulose, D-allulofuranose and ring-opened D-allulose were observed in the catalytic site. However, bound D-allose in the pyranose form was found in the catalytic site of the complex with D-allose, which was unfavorable for recognition, like an inhibition mode. The structure of the complex may explain the low activity toward D-allose. KEY POINTS: • Crystal structures of LrL-RhI in complexes with substrates were determined. • LrL-RhI exhibits enzyme activity toward L-rhamnose, D-allulose, and D-allose. • The LrL-RhI is active in acidic conditions.

Changes in FeNO, d-ROMs, and BH4 by Intravenous L-Arginine in Children and Its Putative Role in Asthma Treatment.

Purpose: Pteridines are metabolites of tetrahydrobiopterin (BH4), being coenzymes for nitric oxide synthase (NOS). No study has clarified the relationship among pteridines and NOS, fractional exhaled nitric oxide (FeNO) generated by pteridines, and reactive oxygen species. In this study, we administered arginine, a precursor of NO, and confirmed changes in the levels of pteridines, FeNO, and reactive oxygen species and their relationship to clarify the pathogenesis of airway inflammation in which oxidative stress is involved, such as bronchial asthma. Patients and Methods: This is a prospective, randomized open-label study. Children, aged 2 to 15 years, who were scheduled for growth hormone stimulation tests and were able to undergo a respiratory function test were recruited. They were randomly divided into two groups: arginine-administered and control groups. In the former, L-arginine hydrochloride was intravenously administered. After administration, the levels of diacron-reactive oxygen metabolites (d-ROMs), serum pteridines, serum amino acids, and fractional exhaled NO (FeNO) were measured. Results: We analyzed 15 children aged 4 to 14 years. In the arginine-administered group, there was an increase in the FeNO level and a decrease in the d-ROMs level, reaching a peak 30 min after administration, compared with the control group. In addition, there was a decrease in the serum biopterin level and an increase in the d-ROMs level, reaching peak 60 min after administration. Conclusion: The administration of L-arginine increased the NO level and decreased the d-ROMs level. Due to this, biopterin may be consumed and decreased, leading to an increase in the d-ROMs level. As a reduction in reactive oxygen species leads to the relief of inflammation, arginine and biopterin may be useful for inhibiting inflammation.

Single-Center Analysis of Pegfilgrastim-induced Aortitis Using a Drug Prescription Database and CT Findings.

Background Pegfilgrastim-induced aortitis is a rare but serious adverse event in patients undergoing anticancer therapy with granulocyte colony-stimulating factor analogs. Despite previous case series and systemic reviews, the exact incidence, clinical presentation, and CT manifestations of pegfilgrastim-induced aortitis remain unclear. Purpose To clarify the incidence and clinicoradiologic characteristics of pegfilgrastim-induced aortitis. Materials and Methods Pegfilgrastim administration records from January 2015 to March 2021 were retrospectively collected from the drug prescription database of a single center and were matched with the relevant findings in the CT database. Corresponding CT images within 6 months were available for a total of 1462 doses of pegfilgrastim in 674 patients. Four radiologists reviewed the CT images for the presence of aortitis in two steps. Clinical information and the distribution of aortitis on CT images were examined for patients with a diagnosis of pegfilgrastim-induced aortitis. Results Pegfilgrastim-induced aortitis was observed in 18 of 674 patients (mean age, 62 years ± 13 [SD]; 424 men), resulting in incidence rates of 2.7% per patient (95% CI: 1.6, 4.2) and 1.2% per dose (95% CI: 0.7, 1.9). The most common original primary malignancies were esophageal cancer (n = 10, 9%), breast cancer (n = 3, 4%), and pancreatic cancer (n = 2, 2%). The most common anticancer drugs used at onset were 5-fluorouracil, cisplatin, and docetaxel. Seven cases were symptomatic, while the remaining 11 (61%) were asymptomatic. CT findings indicated that aortitis involved branches of the aortic arch in 13 cases (72%), aortic arch in 10 cases (56%), and abdominal aorta in two cases (11%). Conclusion Pegfilgrastim-induced aortitis may be more prevalent than previously reported and may be more common in patients with esophageal cancer and those who received 5-fluorouracil, cisplatin, and docetaxel as anticancer drugs. The findings also suggest that pegfilgrastim-induced aortitis is often characterized by aortic arch and proximal branch involvement at CT. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Krinsky in this issue.

Risk factors for interstitial lung disease induced by gemcitabine plus albumin-bound paclitaxel therapy in pancreatic ductal adenocarcinoma patients.

BACKGROUND: Gemcitabine plus nab-paclitaxel (GnP) therapy is used for unresectable pancreatic ductal adenocarcinoma, but may cause interstitial lung disease (ILD) as a serious side effect. However, the risk factors for ILD in patients receiving GnP therapy are not well established. Here, we retrospectively investigated the incidence of GnP-induced ILD in pancreatic ductal adenocarcinoma patients, and the risk factors. METHODS: We investigated the patients' background, laboratory data, previous treatment history, concomitant medications, number of doses of GnP, cumulative dosage and administration period, and occurrence of side effects. RESULTS: Of the 105 patients included in this study, ILD occurred in 10 (9.5%). Patients with ILD had a significantly higher frequency of concomitant treatment with Kampo medicines, especially goshajinkigan, which is considered to help prevent chemotherapy-induced peripheral neuropathy (CIPN) (odds ratio: 11.5, 95% confidence interval: 2.67-49.38). No significant differences were observed in other clinical characteristics. Notably, the severity of CIPN in patients who used goshajinkigan for prevention was not significantly different from that in patients who did not use goshajinkigan in this study. CONCLUSIONS: These results suggest that administration of goshajinkigan to patients receiving GnP therapy for prevention of CIPN may need to be reconsidered.