Quantifying Plant Viruses: Evolution from Bioassay to Infectivity Dilution Curves along the Model of Tobamoviruses.

This review describes the development of the bioassay as a means of quantifying plant viruses, with particular attention to tobamovirus. It delves into various models used to establish a correlation between virus particle concentration and the number of induced local lesions (the infectivity dilution curve), including the Poisson, Furumoto and Mickey, Kleczkowski, Growth curve, and modified Poisson models. The parameters of each model are described, and their application or performance in the context of the tobacco mosaic virus is explored. This overview highlights the enduring value of the infectivity dilution curve in tobamovirus quantification, providing valuable insights for researchers or practitioners of bioassays and theoreticians of modeling.

Vehicle Headlight Halo Simulation of Presbyopia-Correcting Intraocular Lenses.

Purpose: This optical bench study was designed to evaluate and compare the halos generated by presbyopia-correcting intraocular lenses (PCIOLs) and monofocal intraocular lenses (IOLs), with or without lens decentration, using an optical bench to simulate the headlight of a distant vehicle in mesopic conditions. Methods: Halos generated by six nondiffractive and 10 diffractive IOLs with different dioptric add powers were evaluated using a high dynamic range bench system. Halo intensities were compared by assessing the area under the measured intensity profile curve to compute the relative halo magnitude (RHM). Results: Nondiffractive PCIOLs produced smaller and less intense bench halo images than diffractive ones. RHM measurements ranged from 964 to 1896. Monofocal IOLs produced lower RHM values, whereas diffractive PCIOLs generated higher ones. When decentered by 0.5 mm with respect to the system aperture, more obviously asymmetric halo image profiles were observed in diffractive compared with nondiffractive PCIOLs. Conclusions: Simulated bench halos of nondiffractive PCIOLs are smaller and less intense than those of diffractive PCIOLs. Additional clinical studies assessing standardized patient-reported outcomes measures are required to correlate these bench results with patient satisfaction. Translational Relevance: This study contrasts the design-related simulated bench halos of nondiffractive and diffractive PCIOLs, aiming to elucidate their impact on halo perception.

Methods of competing risks flexible parametric modeling for estimation of the risk of the first disease among HIV infected men.

BACKGROUND: Patients infected with the Human Immunodeficiency Virus (HIV) are susceptible to many diseases. In these patients, the occurrence of one disease alters the chance of contracting another. Under such circumstances, methods for competing risks are required. Recently, competing risks analyses in the scope of flexible parametric models have risen to address this requirement. These lesser-known analyses have considerable advantages over conventional methods. METHODS: Using data from Multi Centre AIDS Cohort Study (MACS), this paper reviews and applies methods of competing risks flexible parametric models to analyze the risk of the first disease (AIDS or non-AIDS) among HIV-infected patients. We compared two alternative subdistribution hazard flexible parametric models (SDHFPM1 and SDHFPM2) with the Fine & Gray model. To make a complete inference, we performed cause-specific hazard flexible parametric models for each event separately as well. RESULTS: Both SDHFPM1 and SDHFPM2 provided consistent results regarding the magnitude of coefficients and risk estimations compared with estimations obtained from the Fine & Gray model, However, competing risks flexible parametric models provided more efficient and smoother estimations for the baseline risks of the first disease. We found that age at HIV diagnosis indirectly affected the risk of AIDS as the first event by increasing the number of patients who experience a non-AIDS disease prior to AIDS among > 40 years. Other significant covariates had direct effects on the risks of AIDS and non-AIDS. DISCUSSION: The choice of an appropriate model depends on the research goals and computational challenges. The SDHFPM1 models each event separately and requires calculating censoring weights which is time-consuming. In contrast, SDHFPM2 models all events simultaneously and is more appropriate for large datasets, however, when the focus is on one particular event SDHFPM1 is more preferable.

The relation of secondary sex ratio and miscarriage history with Toxoplasma gondii infection.

BACKGROUND: Toxoplasma gondii is a protozoan parasite with worldwide distribution, infecting a broad-range of humans and warm-blooded animals. In the current study, role of this parasite on secondary sex ratio and risk of miscarriage was investigated. METHODS: In this cross-sectional study, 850 cord blood samples were collected in Tehran, Iran, 2014-2015. Enzyme-linked immunosorbent assay (ELISA) was used to assess anti-Toxoplasma IgG in samples. Information such as sex of the neonates and age, number of previous pregnancies and history of miscarriage of the mothers were recorded in questionnaires. Logistic regression analysis was used to assess the possible relationship between the latent toxoplasmosis and the highlighted parameters. RESULTS: Logistic regression analysis showed that the odds of having a male neonate in seropositive women is nearly 64% higher than that in seronegative women (OR = 1.64, CI95 = 1.16-2.33, P = 0.005). The odds ratio of having male neonate increased to 2.10 (CI95 = 1.24-3.57, P = 0.006) in high-titer seropositive women, compared to that in seronegative control group. The odds of having a miscarriage history was approximately two and a half times greater in seropositive women than in seronegative ones (OR = 2.45, CI95 = 1.56-3.87, P < 0.001). The odds ratio of having miscarriage increased to 2.76 (CI95 = 1.61-4.73, P < < .001) in low-titer seropositive women, compared to that in seronegative control group. CONCLUSION: Results of the current study have shown that T. gondii infection affects secondary sex ratio in human offspring and can be addressed as one of the major miscarriage causes in women.