The 'X' Factor: Exploring COVID-19 Viral Shedding in X-Linked Agammaglobulinemia. Can PCR Cell Cycle Threshold Play a Role?

Abstract Background Multiple studies worldwide reported the clinical and epidemiological features of coronavirus disease 2019 (COVID-19) with limited reports form the Middle East area. Methods This is an observational study to describe the clinical and epidemiological features of 341 COVID-19 cases in the Eastern Province of Saudi Arabia over the first three months from reporting the first case in the country and identify factors associated with severity of the illness. Results The median age was 45 years and males were twice as affected as females (p value < 0.0001). The duration of viral shedding ranged from 9 to 36 days. The most common clinical presentations include fever, shortness of breath, cough, myalgia, sore throat, vomiting, and headache. Severe and critical cases were significantly higher in males compared to females (23% vs 8.7%), senior adults (> 65 years), Bengali ethnicity, and in patient with com-morbidities including diabetes, hypertension, and dyslipidemia (p-value = 0.001). Furthermore, case fatality rate was found to be 10% and was significantly higher in male gender compared to female (13.8%vs 2.6%), and in Asian ethnicity (17.9%) compared to Arabs (6%) and African counterparts (0) (p-value = 0.002). No association was found between viral load represented by the RT-PCR cycle threshold (Ct) values and severity of illness. Conclusion Age, gender and ethnicity are important predictors of COVID-19 severity while Cycle threshold (Ct) of SARS-CoV-2 RT-PCR test cannot be used as a predictor of criticality of illness.

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SARS-CoV-2 Viral RNA Load Dynamics in the Nasopharynx of Infected Children

10.1101/2020.08.31.20185488 ◽

2020 ◽

Author(s):

Kai-qian Kam ◽

Koh Cheng Thoon ◽

Matthias Maiwald ◽

Chia Yin Chong ◽

Han Yang Soong ◽

...

Keyword(s):

Viral Load ◽

Early Stage ◽

Transmission Potential ◽

Cycle Threshold ◽

Viral Loads ◽

Viral Shedding ◽

Asymptomatic Children ◽

Peak Viral Load ◽

Epidemiological Risk ◽

Mean Cycle

It is important to understand the temporal trend of pediatric severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral load to estimate the transmission potential of children in schools and communities. We determined differences in SARS-CoV-2 viral load dynamics between nasopharyngeal samples of infected asymptomatic and symptomatic children. The daily cycle threshold values of SARS-CoV-2 in the nasopharynx of a cohort of infected children were collected for analysis. Among 17 infected children, 10 (58.8%) were symptomatic. Symptomatic children, when compared to asymptomatic children, had higher viral load (mean cycle threshold on day 7 of illness 28.6 versus 36.7, p = 0.02). Peak SARS-CoV-2 viral loads occured around days 2-3 of illness/days of diagnosis in infected children. After adjusting for the estimated date of infection, the higher SARS-CoV-2 viral loads in symptomatic children remained. We postulate that symptomatic SARS-CoV-2-infected children may have higher transmissibility than asymptomatic children. As peak viral load in infected children occurred in the early stage of illness, viral shedding and transmission in the pre-symptomatic phase probable. Our study highlights the importance of screening for SARS-CoV-2 in children with epidemiological risk factors, even when they are asymptomatic in order to improve containment of the virus in the community, including educational settings.

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Lower SARS-CoV-2 viral shedding following COVID-19 vaccination among healthcare workers in Los Angeles, California

Open Forum Infectious Diseases ◽

10.1093/ofid/ofab526 ◽

2021 ◽

Author(s):

Paul C Adamson ◽

Michael A Pfeffer ◽

Valerie A Arboleda ◽

Omai B Garner ◽

Annabelle de St. Maurice ◽

...

Keyword(s):

Los Angeles ◽

Healthcare Workers ◽

Vaccine Dose ◽

Threshold Values ◽

Cycle Threshold ◽

Viral Shedding

Abstract Among 880 healthcare workers with a positive SARS-CoV-2 test, 264 (30.0%) infections were identified following receipt of at least one vaccine dose. Median SARS-CoV-2 cycle threshold values were highest among individuals receiving two vaccine doses, corresponding to lower viral shedding. Vaccination might lead to lower transmissibility of SARS-CoV-2.

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Variable Duration of Viral Shedding in Cancer Patients with COVID-19

Infection Control and Hospital Epidemiology ◽

10.1017/ice.2021.378 ◽

2021 ◽

pp. 1-15

Author(s):

N. Esther Babady ◽

Bevin Cohen ◽

Tara McClure ◽

Karin Chow ◽

Mario Caldararo ◽

...

Keyword(s):

Public Health ◽

Retrospective Study ◽

Cancer Patients ◽

Solid Tumors ◽

Hematologic Malignancy ◽

Important Public Health ◽

Health Implications ◽

Cycle Threshold ◽

Viral Shedding ◽

Variable Duration

Abstract In this retrospective study of 105 SARS COV-2 infected cancer patients with longitudinal nasopharyngeal sampling, the duration of viral shedding and time to attain cycle threshold >30 was longer in patients with hematologic malignancy than those with solid tumors. These findings have important public health implications.

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Utility of Ct values in differentiating COVID-19 reinfection versus prolonged viral shedding in an immunocompromised patient

BMJ Case Reports ◽

10.1136/bcr-2021-243692 ◽

2021 ◽

Vol 14 (7) ◽

pp. e243692

Author(s):

Katherine Julian ◽

Neal Shah ◽

Rashmi Banjade ◽

Dhirisha Bhatt

Keyword(s):

Acute Leukaemia ◽

Immunocompromised Patient ◽

Neutropenic Fever ◽

Threshold Values ◽

Blurred Vision ◽

Cycle Threshold ◽

Viral Shedding

We describe the case of a 26-year-old man who presented to an outside hospital with concerns of blurred vision. He subsequently tested positive for COVID-19 and his lab work suggested acute leukaemia. The patient was admitted to our hospital and completed a course of remdesivir. He eventually tested negative for COVID-19 before initiating chemotherapy. Two days after starting chemotherapy, he developed a neutropenic fever and tested positive for COVID-19. Through this case, we aim to bring attention to patients who recurrently test positive with COVID-19 PCR testing, thereby causing a dilemma of differentiating between reinfections and prolonged shedding of the virus, as well as understand and use cycle threshold values to discern these aetiologies.

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Silent transmission of “COVID-19”: A major concern

International Journal of Research in Pharmaceutical Sciences ◽

10.26452/ijrps.v11ispl1.3715 ◽

2020 ◽

Vol 11 (SPL1) ◽

pp. 1544-1550

Author(s):

Apoorva Mishra ◽

Prachet Dakshinkar ◽

Priyanka Multani

Keyword(s):

Respiratory Tract ◽

Clinical Symptoms ◽

Herd Immunity ◽

Modern Medicine ◽

World Health ◽

Upper Respiratory Tract ◽

Cycle Threshold ◽

Viral Shedding ◽

Asymptomatic Patients ◽

Serial Interval

“Coronavirus disease 2019 “(COVID-19)” has been proclaimed as a public health exigency of global scope by “World Health Organization” and is the latest threat to universal health. Despite of manifesting imperceptible clinical symptoms, asymptomatic carriers of the disease are known to be infectious. The prevalence of “COVID-19” is rising persistently, despite meticulous global confinement and quarantine endeavors. An important element in the devastating transmissibility potential of “COVID-19” is the high titre of virus in oropharynx in the initial progression of disease. On the contrary influenza virus has low titres in upper respiratory tract than lower respiratory tract. Therefore, making the symptom-based assessment strategies less effectual in case of “SARS-CoV-2” According to recent reports, symptomless population along with the individuals with mild disease, are radical transmitters in the proliferation of “COVID-19”. The phenomenon of Viral shedding emphasizes the reasons of asymptomatic patients being rapid transmitters in “SARS-CoV-2” than “SARS-CoV-1”. The significant role of incubation span, cycle threshold values, serial interval cannot be overlooked in asymptomatic transmission. This pandemic is an absolute reminder of the existing challenge posed by the virulent pathogen on modern medicine. Thus, we intend to comprehensively elaborate various outlooks on the asymptomatic spread of “SARS-CoV-2”, including the pathophysiology, viral shedding, cycle threshold, serial interval, incubation span, herd immunity, inefficient testing, prevention and prospective treatment of “COVID-19”.

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Maytansine-Induced Mitotic Arrest in Human Lymphoblasts

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100079747 ◽

1977 ◽

Vol 35 ◽

pp. 460-461

Author(s):

Tai-Te Chao ◽

John Sullivan ◽

Awtar Krishan

Keyword(s):

Electron Microscopy ◽

Cell Cycle ◽

Transmission Electron Microscopy ◽

Tubulin Polymerization ◽

Vinca Alkaloids ◽

Antimitotic Activity ◽

Transmission Electron ◽

Flow Microfluorometry ◽

Brain Tubulin

Maytansine, a novel ansa macrolide (1), has potent anti-tumor and antimitotic activity (2, 3). It blocks cell cycle traverse in mitosis with resultant accumulation of metaphase cells (4). Inhibition of brain tubulin polymerization in vitro by maytansine has also been reported (3). The C-mitotic effect of this drug is similar to that of the well known Vinca- alkaloids, vinblastine and vincristine. This study was carried out to examine the effects of maytansine on the cell cycle traverse and the fine struc- I ture of human lymphoblasts.Log-phase cultures of CCRF-CEM human lymphoblasts were exposed to maytansine concentrations from 10-6 M to 10-10 M for 18 hrs. Aliquots of cells were removed for cell cycle analysis by flow microfluorometry (FMF) (5) and also processed for transmission electron microscopy (TEM). FMF analysis of cells treated with 10-8 M maytansine showed a reduction in the number of G1 cells and a corresponding build-up of cells with G2/M DNA content.

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Fibronexus-Like Adhesion Sites are Present at the Invasive Zones of Human Epidermoid Carcinomas

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100053280 ◽

1982 ◽

Vol 40 ◽

pp. 106-109

Author(s):

Irwin I. Singer

Keyword(s):

Cell Cycle ◽

Serum Concentration ◽

Substrate Binding ◽

High Serum ◽

Adhesion Sites ◽

Substrate Adhesion ◽

Focal Contacts ◽

Adhesion Complex ◽

Low Serum

Our previous results indicate that two types of fibronectin-cytoskeletal associations may be formed at the fibroblast surface: dorsal matrixbinding fibronexuses generated in high serum (5% FBS) cultures, and ventral substrate-adhering units formed in low serum (0.3% FBS) cultures. The substrate-adhering fibronexus consists of at least vinculin (VN) and actin in its cytoplasmic leg, and fibronectin (FN) as one of its major extracellular components. This substrate-adhesion complex is localized in focal contacts, the sites of closest substratum approach visualized with interference reflection microscopy, which appear to be the major points of cell-tosubstrate adhesion. In fibroblasts, the latter substrate-binding complex is characteristic of cultures that are arrested at the G1 phase of the cell cycle due to the low serum concentration in their medium. These arrested fibroblasts are very well spread, flattened, and immobile.

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Immunocytochemical studies on the behavior of RuBisCO and LHCP II during the cell cycle of synchronized Euglena gracilis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100160868 ◽

1990 ◽

Vol 48 (3) ◽

pp. 662-663

Author(s):

Tetsuaki Osafune ◽

Shuji Sumida ◽

Tomoko Ehara ◽

Eiji Hase ◽

Jerome A. Schiff

Keyword(s):

Cell Cycle ◽

Immunoelectron Microscopy ◽

Growth Phase ◽

Euglena Gracilis ◽

Dark Period ◽

Light Period ◽

Carboxylase Activity ◽

Immunocytochemical Studies ◽

Lhcp Ii

Changes in the morphology of pyrenoid and the distribution of RuBisCO in the chloroplast of Euglena gracilis were followed by immunoelectron microscopy during the cell cycle in a light (14 h)- dark (10 h) synchronized culture under photoautotrophic conditions. The imrnunoreactive proteins wereconcentrated in the pyrenoid, and less densely distributed in the stroma during the light period (growth phase, Fig. 1-2), but the pyrenoid disappeared during the dark period (division phase), and RuBisCO was dispersed throughout the stroma. Toward the end of the division phase, the pyrenoid began to form in the center of the stroma, and RuBisCO is again concentrated in that pyrenoid region. From a comparison of photosynthetic CO2-fixation with the total carboxylase activity of RuBisCO extracted from Euglena cells in the growth phase, it is suggested that the carboxylase in the pyrenoid functions in CO2-fixation in photosynthesis.

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