A Japanese Case of COVID-19 Caused by Omicron Strain with Y453F Substitution

Frequent mutations of SARS-CoV-2 change the strain more transmissible, leading to the pandemic in worldwide. We detected Y453F substitution on Omicron strain, isolated from a Japanese patient in July 2022. While Y453F substitution was identified B1.1.298 lineage in Netherlands and Denmark in 2020, the substitution has not been reported in Omicron strain especially in Japan. Y453F substitution is associated with higher viral infectivity because it is sited in the receptor-binding domain (RBD), and Y453F substitution contributes to increase binding affinity to angiotensin converting enzyme 2 (ACE2). Additionally, Y453F substitution has been reported to escape human leukocyte antigen (HLA), which is known to recognize non-self-antigens in virus-infected cells as cellular immunity, so it should be closely monitored.

Case report: therapeutic monitoring of vancomycin in an acute liver failure patient with anuria under high-flow continuous hemodiafiltration

BACKGROUND

High-flow continuous hemodiafiltration (HF-CHDF) combines diffusive and convective solute removal and is employed for artificial liver adjuvant therapy. However, there is no report on dosage planning of vancomycin (VCM) in patients with acute liver failure under HF-CHDF.

CASE PRESENTATION

A 20-year-old woman (154 cm tall, weighing 50 kg) was transferred to the intensive care unit (ICU) with acute liver failure associated with autoimmune liver disease. On the following day, HF-CHDF was started due to elevated plasma ammonia concentration. On ICU day 8, VCM was started for suspected pneumonia and meningitis (30 mg/kg loading dose, then 20 mg/kg every 12 hrs). However, on ICU day 10, VCM blood concentration was under the limit of detection (< 3.0 μg/mL) and the patient developed anuria. The VCM dose was increased to 20 mg/kg every 6 hrs. Calculation with a one-compartment model using the HF-CHDF blood flow rate as a surrogate for VCM clearance, together with hematocrit and protein binding ratio, predicted a trough VCM blood concentration of 15 μg/mL. The observed concentration was about 12 μg/mL. The difference may represent non-HF-CHDF clearance. Finally, living donor liver transplantation was performed.

CONCLUSION

We report an acute liver failure patient with anuria under HF-CHDF in whom VCM administration failed to produce an effective blood concentration, likely due to HF-CHDF-enhanced clearance. VCM dosage adjustment proved successful, and was confirmed by calculation using a one-compartment model.

Systematic active environmental surveillance successfully identified and controlled the Legionella contamination in the hospital

INTRODUCTION

Legionella disease can manifest as severe respiratory tract infection with a high mortality rate and is sometimes associated with a hospital outbreak by a contaminated water supply. A patient with breast cancer admitted about a month before. High fever was observed 18 days after admission and the Legionella antigen test showed the positive result.

METHODS

Due to the incidence of Legionella infection, we demonstrated the active surveillance of Legionella contamination in the entire hospital.

RESULTS

Cultures of her environmental samples revealed that hot water in two bathrooms were contaminated with Legionella. In our hospital, the hot water is heated and pumped up on the roof and distributed to each room. The contaminated bathrooms were related to the same plumbing. Therefore, we further collected samples throughout the hot water system. Legionella was not detected in the central part of the system. However, we detected Legionella in the hot water sampled from other five rooms, which were also associated with the same plumbing of the two bathrooms. The temperature and chlorine concentration of the hot water were not high enough to inactivate Legionella at the end of the plumbing. After the adjustment of the water temperature and chlorine concentration, Legionella became undetectable. Our prompt and active surveillance successfully identified the plumbing of the hot water system as the source of Legionella contamination and took precautions against future outbreaks.

CONCLUSIONS

Monitoring of water temperature and chloride concentration at the end of the hot water circulation is important to prevent nosocomial Legionella disease.

Ceftriaxone-induced encephalopathy in a patient with a solitary kidney

Ceftriaxone (CRO) is a long-acting third-generation cephalosporin antibiotic. We present a case of CRO-induced encephalopathy in an 84-year-old male patient with a solitary right kidney, admitted with bilateral pneumonia and right pyelonephritis. Intravenous CRO (2 g, every 24 hr) was started for the infection, but tonic-clonic seizures of the left face and left upper extremity appeared on the 8th day. To examine the relationship between CRO administration and the seizures, we measured CRO concentrations in the patients' plasma/serum and cerebrospinal fluid (CSF). The CRO concentration in blood at the onset of encephalopathy was estimated to have been approximately 60 μg/mL based on a simulation curve. We also calculated the pharmacokinetic parameters after CRO administration. The patient had about one-tenth of the total body clearance and one-third of the volume of distribution compared with healthy adults, and the elimination half-life was about 3 times longer.

Initial Serum C-reactive Protein Level as a Predictor of Increasing Serum Vancomycin Concentration During Treatment

BACKGROUND

Vancomycin has a narrow therapeutic window, and an increase in its serum concentration-to-dose ratio during treatment can cause renal toxicity. Therefore, this study was aimed at finding a marker to identify patients at risk of increasing serum vancomycin during treatment.

METHODS

This was a retrospective cohort study of patients treated with vancomycin at Kanazawa University Hospital, Japan, from April 2012 to May 2015. Spearman correlation coefficients were calculated to determine the correlations between changes in vancomycin concentration-to-dose ratio and initial values or changes in laboratory data and other parameters. In addition, a multiple regression analysis was conducted.

RESULTS

One hundred ninety-nine patients for whom 2 or more points of data on therapeutic drug monitoring (TDM) of intravenous vancomycin treatment were available and did not undergo dialysis were included in the study. Changes in vancomycin concentration-to-dose ratio were associated with C-reactive protein (CRP) and sodium (Na) levels on the initial day of TDM and with changes in white blood cell count, Na, and estimated glomerular filtration rates (eGFRs). Multiple regression analysis helped identify CRP and Na levels on the initial day of TDM and change in eGFR as independent influencing variables.

CONCLUSIONS

A high serum CRP level on the initial day of TDM is an independent predictor of increasing vancomycin concentration-to-dose ratio in patients receiving intravenous vancomycin treatment, even if eGFR remains unchanged.

Severe intoxication caused by sodium-glucose cotransporter 2 inhibitor overdose: a case report

Background

Sodium-glucose cotransporter 2 (SGLT2) inhibitors inhibit SGLT2, which is expressed in the proximal renal tubule, and thus reduce blood glucose levels by enabling the urinary excretion of excess glucose. SGLT2 inhibitors have been reported to suppress the complications of diabetes and reduce overall mortality. However, little is known about the types of symptoms that may occur in response to an overdose of an SGLT2 inhibitor. Here, we describe a case of intoxication caused by an overdose of an SGLT2 inhibitor.

Case presentation

An otherwise physically healthy adult woman ingested an overdose of ipragliflozin, an SGLT2 inhibitor, and a polypill of olmesartan medoxomil, and azelnidipine in a suicide attempt. Although her blood ipragliflozin concentration was very high (9516.3 ng/mL) upon hospital arrival, her initial blood glucose level was normal, and she did not exhibit symptoms such as hypoglycemia or polyuria. Moderate renal dysfunction associated with an estimated glomerular filtration rate of 42.3 mL/min/1.73 m² was observed. Thirty-six hours after ingestion, her blood ipragliflozin concentration decreased to a level equivalent to that observed after a therapeutic dose and her renal function improved almost simultaneously. After improvement in her renal function, the osmotic diuretic effect of the drug progressed. Her blood glucose level declined slightly but was in the normal range due to glucose administration. During the clinical course, fatal hypoglycemia was not observed.

Conclusions

Our case showed that an overdose of an SGLT2 inhibitor caused toxic effects on renal function, but severe hypoglycemia was not observed. Additional cases of intoxication from SGLT2 inhibitors alone would be helpful to clarify the mechanism of intoxication.

mTOR inhibitors control the growth of EGFR mutant lung cancer even after acquiring resistance by HGF

Resistance to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs), gefitinib and erlotinib, is a critical problem in the treatment of EGFR mutant lung cancer. Several mechanisms, including bypass signaling by hepatocyte growth factor (HGF)-triggered Met activation, are implicated as mediators of resistance. The mammalian target of rapamycin (mTOR), is a downstream conduit of EGFR and MET signaling, and is thus considered a therapeutically attractive target in the treatment of various types of cancers. The purpose of this study was to examine whether 2 clinically approved mTOR inhibitors, temsirolimus and everolimus, overcome HGF-dependent resistance to EGFR-TKIs in EGFR mutant lung cancer cells. Both temsirolimus and everolimus inhibited the phosphorylation of p70S6K and 4E-BP1, which are downstream targets of the mTOR pathway, and reduced the viability of EGFR mutant lung cancer cells, PC-9, and HCC827, even in the presence of HGF in vitro. In a xenograft model, temsirolimus suppressed the growth of PC-9 cells overexpressing the HGF-gene; this was associated with suppression of the mTOR signaling pathway and tumor angiogenesis. In contrast, erlotinib did not suppress this signaling pathway or tumor growth. Multiple mechanisms, including the inhibition of vascular endothelial growth factor production by tumor cells and suppression of endothelial cell viability, contribute to the anti-angiogenic effect of temsirolimus. These findings indicate that mTOR inhibitors may be useful for controlling HGF-triggered EGFR-TKI resistance in EGFR mutant lung cancer, and they provide the rationale for clinical trials of mTOR inhibitors in patients stratified by EGFR mutation and HGF expression status.

Paracrine receptor activation by microenvironment triggers bypass survival signals and ALK inhibitor resistance in EML4-ALK lung cancer cells

PURPOSE

Cancer cell microenvironments, including host cells, can critically affect cancer cell behaviors, including drug sensitivity. Although crizotinib, a dual tyrosine kinase inhibitor (TKI) of ALK and Met, shows dramatic effect against EML4-ALK lung cancer cells, these cells can acquire resistance to crizotinib by several mechanisms, including ALK amplification and gatekeeper mutation. We determined whether microenvironmental factors trigger ALK inhibitor resistance in EML4-ALK lung cancer cells.

EXPERIMENTAL DESIGN

We tested the effects of ligands produced by endothelial cells and fibroblasts, and the cells themselves, on the susceptibility of EML4-ALK lung cancer cell lines to crizotinib and TAE684, a selective ALK inhibitor active against cells with ALK amplification and gatekeeper mutations, both in vitro and in vivo.

RESULTS

EML4-ALK lung cancer cells were highly sensitive to ALK inhibitors. EGF receptor (EGFR) ligands, such as EGF, TGF-α, and HB-EGF, activated EGFR and triggered resistance to crizotinib and TAE684 by transducing bypass survival signaling through Erk1/2 and Akt. Hepatocyte growth factor (HGF) activated Met/Gab1 and triggered resistance to TAE684, but not crizotinib, which inhibits Met. Endothelial cells and fibroblasts, which produce the EGFR ligands and HGF, respectively, decreased the sensitivity of EML4-ALK lung cancer cells to crizotinib and TAE684, respectively. EGFR-TKIs resensitized these cells to crizotinib and Met-TKI to TAE684 even in the presence of EGFR ligands and HGF, respectively.

CONCLUSIONS

Paracrine receptor activation by ligands from the microenvironment may trigger resistance to ALK inhibitors in EML4-ALK lung cancer cells, suggesting that receptor ligands from microenvironment may be additional targets during treatment with ALK inhibitors.

[Study of monocyte function in patients with cervical cancer by using T-lymphocyte monocyte interaction in response to phytohemagglutinin (author's transl)]

Monocytes have been thought to play an important role in the immune surveillance system of cancer patients since monocytes were shown to participate as accessory cells in the induction of T-cell proliferation to PHA by Potter et al. in 1977. We had already reported the depression of monocyte function with the progress of cancer after PHA response of mononuclear cells obtained by centrifugation of Ficoll-Hypaque and lymphocytes obtained by depletion of monocytes ingesting Silica from mononuclear cells was compared in cancer patients. In that study, however, monocyte function was considered not to be indicated truly because responding cells were different at each examination. Therefore, in this study responding cells were graded as T-cells obtained from healthy volunteers and monocytes were added to the T-cells. Monocyte function in this study was as follows: PHA response to T-cells and monocytes over PHA response to T-cells. In this study, monocytes were allogenic to T-cells. At first, the influence of monocytes to allogenic T-cells was studied but it was found to be negligible. The ratio of monocytes and T-cells was 1:1. The concentration of PHA was 20 micrograms/ml. Finally, the monocyte function of patients with cervical cancer was studied. It was increased at the stage of CIS and then gradually decreased. At the advanced stage, it was significantly decreased to comparison with that of healthy volunteers.

The prognostic value of serum immunosuppressive effect in patients with ovarian cancer

Sixteen patients who underwent surgery and postoperative chemotherapy for carcinoma of the ovary were studied. Eleven survived more than 18 months without evidence of recurrence, and 5 died more than 5 months after surgery. Serial determinations were made preoperatively and postoperatively of the immunosuppressive effect of the serums of these patients on the response of normal lymphocytes to phytohemagglutinin stimulation. These determinations were plotted for each patient; the shapes of the curves for patients who survived are markedly different from those of patients who died. The prognostic value of these findings is discussed.

Immunosuppressive effect of serum in patients with ovarian carcinoma

Cell-mediated immune response was measured in 23 patients with ovarian cystadenocarcinoma, 38 patients with benign ovarian tumor, and 44 healthy volunteers. The method used two indexes: the lymphocyte response per unit volume of peripheral blood to phytohemagglutinin (PHA) and the immunosuppressive effect of serum on the response of normal lymphocytes to PHA stimulation. The lymphocyte response per 50 microliter peripheral blood did not differ significantly between patients with ovarian cancer and healthy volunteers. The serum effect, in contrast, differed significantly between malignant and benign ovarian tumors, and was found to increase significantly even when the cancer masses were as small as about 5 x 5 x 5 cm in size, ie, in FIGO Stage I. It is our belief that the measurement of the serum effect in patients with any ovarian tumor enables the early detection of ovarian cancer.