Publications by authors named "Louis Y A Chai"

In subjects with peculiar susceptibility to severe infections by common pyogenic bacteria, mutations of interleukin-1 receptor-associated kinase proteins (IRAK)1 and IRAK4 had been identified. The IRAK kinases function as downstream signal transductors following the activation of pathogen recognition receptors. In two patients with sequential or repeated invasive infections: herpes simplex virus-triggered hemophagocytic lymphohistiocytosis with tuberculosis, and Streptococcus pneumoniae bacteremia with candidemia respectively, novel mutations of IRAK2 were identified.

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  • A study involving 17 patients treated with autologous CAR T cells that target CD7 showed incredible success, with 16 patients achieving minimal residual disease-negative complete remission in less than a month, despite significant leukemia presence.
  • The treatment had mild side effects, and a significant number of patients remained relapse-free, suggesting that anti-CD7 CAR T cell therapy is a promising option for T-ALL.
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  • Molecular chaperons, particularly mitochondrial ones like TRAP1, are important for protein folding, tissue health, and may play a role during infections by regulating processes like oxidative phosphorylation and apoptosis.
  • A case study of a healthy Asian female who developed severe respiratory failure linked to CD4 lymphocytopenia revealed two rare mutations in TRAP1, indicating a connection to her vulnerability to opportunistic infections.
  • The study showed that these TRAP1 mutations led to decreased TRAP1 expression, increased activation of certain caspases, and impaired cellular functions like respiration and glycolysis, highlighting the crucial role of TRAP1 in immune response and disease susceptibility.
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The 'rule-of-6' prediction tool was shown to be able to identify COVID-19 patients at risk of adverse outcomes. During the pandemic, we frequently observed hyponatremia at presentation. We sought to evaluate if adding hyponatremia at presentation could improve the 'rule-of-6' prediction tool.

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Objectives: To investigate multi-dose and timings of COVID-19 vaccines in preventing antenatal infection.

Design: Prospective observational study investigating primary vaccinations, boosters, antenatal COVID-19 infections, neutralizing antibody (Nab) durability, and cross-reactivity to Delta and Omicron variants of concern (VOCs).

Results: Ninety-eight patients completed primary vaccination prepregnancy (29.

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Due to the paucity of longitudinal molecular studies of COVID-19, particularly those covering the early stages of infection (Days 1-8 symptom onset), our understanding of host response over the disease course is limited. We perform longitudinal single cell RNA-seq on 286 blood samples from 108 age- and sex-matched COVID-19 patients, including 73 with early samples. We examine discrete cell subtypes and continuous cell states longitudinally, and we identify upregulation of type I IFN-stimulated genes (ISGs) as the predominant early signature of subsequent worsening of symptoms, which we validate in an independent cohort and corroborate by plasma markers.

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We describe bedside-to-bench immunological and genetic elucidation of defective pyroptosis attributable to novel caspase 4 defect mediating pathogen-triggered inflammatory programmed cell death, in the setting of severe pneumonia and abscess-forming melioidosis in an overtly healthy host failing to clear Burkholderia pseudomallei infection, and how targeted adjunctive biological therapy led to a successful outcome.

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Importance: Despite patients with cancer being at risk of poor outcomes from COVID-19, there are few published studies for vaccine efficacy in this group, with suboptimal immunogenicity and waning vaccine efficacy described in small studies being a concern.

Objective: To assess the incidence rate of severe COVID-19 disease outcomes associated with the number of vaccine doses received and the waning of protection over time.

Design, Setting, And Participants: A prospective multicenter observational cohort study was carried out over 2 time periods (September 15, 2021, to December 20, 2021 [delta wave], and January 20, 2022, to November 11, 2022 [omicron wave]) predominated by SARS-CoV-2 delta and omicron variants, respectively.

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The ideal strategy to fight an infection involves both (i) weakening the invading pathogen through conventional antimicrobial therapy, and (ii) strengthening defense through the augmentation of host immunity. This is even more pertinent in the context of invasive fungal infections whereby the majority of patients have altered immunity and are unable to mount an appropriate host response against the pathogen. Natural killer (NK) cells fit the requirement of an efficient, innate executioner of both tumour cells and pathogens - their unique, targeted cell killing mechanism, combined with other arms of the immune system, make them potent effectors.

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is an opportunistic pathogen, with its infection as one of the causes of morbidity or mortality. Notably, the probiotic yeast var. boulardii has shown the potential to fight against infections.

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  • Three doses of SARS-CoV-2 mRNA vaccines are recommended for cancer patients to decrease severe disease risk, especially given that ongoing anti-cancer treatments can impact vaccine effectiveness.
  • Researchers evaluated 273 cancer patients (both solid and blood cancers) between July 2021 and March 2022, measuring immune responses after each vaccine dose.
  • The study found that while seroconversion rates improved with each dose (35.2% after 1 dose, 79.4% after 2 doses, and 92.4% after 3 doses), patients on active treatment for blood cancers had significantly lower antibody levels compared to those on immunotherapy and chemotherapy.
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Introduction: Invasive fungal infections (IFIs) in Asia/Pacific are a particular threat to patients with malignancies, uncontrolled diabetes mellitus or undiagnosed/untreated human immunodeficiency virus infection and acquired immunodeficiency syndrome (HIV/AIDS). Adequate and early access to diagnostic tools and antifungals is essential for IFI clinical management and patient survival.

Methods: Details on institution profile, self-perception on IFI, and access to microscopy, culture, serology, antigen detection, molecular testing, and therapeutic drug monitoring for IFI were collected in a survey.

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Resistance to azoles in Candida tropicalis is increasing and may be mediated by genetic characteristics. Using whole genome sequencing (WGS), we examined the genetic diversity of 82 bloodstream C. tropicalis isolates from two countries and one ATCC strain in a global context.

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Human cells homozygous for rare loss-of-expression (LOE) TYK2 alleles have impaired, but not abolished, cellular responses to IFN-α/β (underlying viral diseases in the patients) and to IL-12 and IL-23 (underlying mycobacterial diseases). Cells homozygous for the common P1104A TYK2 allele have selectively impaired responses to IL-23 (underlying isolated mycobacterial disease). We report three new forms of TYK2 deficiency in six patients from five families homozygous for rare TYK2 alleles (R864C, G996R, G634E, or G1010D) or compound heterozygous for P1104A and a rare allele (A928V).

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Host factors leading to pulmonary nontuberculous mycobacteria (PNTM) disease are poorly understood compared with disseminated NTM disease, which is linked to the interleukin 12-interferon gamma signaling pathway. We investigated the tumor necrosis factor receptor associated factor 3 (TRAF3) R338W variant in a patient with recurrent PNTM infection, demonstrating TRAF3- and TNF-α-deficient phenotypes via ex vivo immune and cloning-transfection cellular studies.

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  • Nanomedicine and drug interventions for COVID-19 have adapted during the pandemic due to evolving virus variants and declining efficacy of early therapies like antibodies.
  • This study utilized an AI platform called IDentif.AI to analyze the interactions between six experimental and current drugs against the Omicron variant, assessing both individual and combinatorial effects.
  • Findings showed that while individual drugs had limited effectiveness, certain combinations (like EIDD-1931 with YH-53) exhibited significant synergistic interactions, highlighting the potential for combination therapies to improve treatment options for COVID-19 and future pathogens.
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IDentif.AI-x, a clinically actionable artificial intelligence platform, was used to rapidly pinpoint and prioritize optimal combination therapies against COVID-19 by pairing a prospective, experimental validation of multi-drug efficacy on a SARS-CoV-2 live virus and Vero E6 assay with a quadratic optimization workflow. A starting pool of 12 candidate drugs developed in collaboration with a community of infectious disease clinicians was first narrowed down to a six-drug pool and then interrogated in 50 combination regimens at three dosing levels per drug, representing 729 possible combinations.

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Importance: Patients with cancer have an increased risk of severe disease and mortality from COVID-19, as the disease and antineoplastic therapy cause reduced vaccine immunogenicity. Booster doses have been proposed to enhance protection, and efficacy data are emerging from several studies.

Objective: To evaluate the proportion of COVID-19 primary vaccination non-responders with cancer who seroconvert after a booster dose.

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  • The study aimed to compare how effective COVID-19 vaccines are for people with compromised immune systems versus those with healthy immune systems.
  • Researchers conducted a systematic review and meta-analysis using data from various reputable sources for studies published between December 2020 and November 2021.
  • The results indicated that patients with hematological cancers, inflammatory disorders, and solid cancers had significantly lower seroconversion rates after vaccination, with organ transplant recipients showing an extremely low likelihood of developing antibodies.
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Objectives: Highly effective vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been developed but variants of concerns are worrisome, especially B.1.617.

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The existence of a hyperinflammatory state has been observed in patients with invasive fungal infections (IFI). It is being postulated whether morbidity from IFI may, in part, be a consequence of an unnecessarily prolonged or exaggerated proinflammatory immune response including interleukin 6 (IL-6) post-infection, in a host with dysregulated or compromised immunity. This, in turn, induces collateral host injury at the tissue and organ level, leading to adverse outcomes.

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There have been recent descriptions of the novel coronavirus disease 2019 (COVID-19) presenting as 'varicella-like exanthem'. We report three cases of patients with Varicella-Zoster Virus (VZV) and COVID-19 co-infections, presenting in three varied ways. These cases highlight the need for heightened alertness to how such co-infections can present, to pick up overlapping 'dual pathologies' during this current pandemic given that infection control measures including airborne precautions are crucial for both COVID-19 and VZV.

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Diagnostic tests for fungi provide the mycological evidence to strengthen diagnosis of invasive fungal disease. Conventional microbiology and histopathology have their limitations. Recognizing this, there have been attempts at developing new methods to improve yield of diagnosing invasive fungal disease (IFD).

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