Is Hepatitis C Virus Positivity a Contributing Factor to Occult Hepatitis B Virus Infection in Hemodialysis Patients?

Hepatitis B (HBV) infections continue to occur in adult hemodialysis units. Occult HBV infection (serum hepatitis B surface antigen [HBsAg] negative but HBV DNA positive) may be a contributing factor in these patients. This study was designed to (1) investigate the prevalence of occult HBV infection in hemodialysis patients and (2) compare the prevalence of occult HBV infection among hepatitis C (HCV)-positive and HCV-negative hemodialysis patients. The study included 138 patients on chronic hemodialysis. Eighty-four patients were HCV positive and 54 were HCV negative. HBV DNA testing was performed by polymerase chain reaction. We also recorded general characteristics of the patients, duration of hemodialysis, and serum alanine aminotransferase and aspartate aminotransferase levels. Twenty-one (15.2%) of the 138 hemodialysis patients were HBV DNA positive. Nine (16.6%) of the 54 anti-HCV antibody negative hemodialysis patients were HBV DNA positive. Twelve (14.2%) of the 84 anti-HCV antibody positive patients were HBV DNA positive. The prevalence in anti-HCV Ab positive and negative hemodialysis patients were same (P > .05). Hemodialysis duration, demographic features, and biochemical parameters were not significantly different in patients with and without occult HBV infection in both HCV-positive and -negative hemodialysis patients (P > .05). HCV positivity is not a contributing factor to occult HBV infection in hemodialysis patients. None of the parameters tested help to distinguish patients with occult HBV infection from those who are HBV DNA negative.     

Comparative evaluation of the effect of diameter, length and number of implants supporting three-unit fixed partial prostheses on stress distribution in the bone.

OBJECTIVES: The purpose of this study was to compare the effects of the diameter, the length and the number of implants on stress distribution in the bone around the implants supporting three-unit fixed partial prostheses in the mandibular posterior edentulism. MATERIALS AND METHOD: A mandibular Kennedy II three-dimensional finite element model was constructed. Four fixed partial prostheses with two terminal implant supports of various lengths and diameters, and two fixed partial prostheses with three implant supports of various lengths were designed. In separate load cases, 400 N oblique, 200 N vertical, and 57 N horizontal forces were simulated. The tensile and the compressive stress values in the cortical bone around the collar of the implants and Von Mises stresses in the implants were evaluated. RESULTS: Although the change in the length of implants did not decrease the stress levels, lower tensile and compressive stress values were observed in the bone for wider implant placement configurations. Similar stress distributions and close stress levels were observed for two wider implant supports in comparison with the three-implant-supported fixed partial prostheses. CONCLUSION: With the use of two implants of 4.1-mm diameter and 10-mm length as terminal supports for three-unit fixed prostheses, the magnitude and the distribution of stresses in the cortical bone around the implant collar is within the normal physiological limits.     

Effector memory T cell subset CD45RA−CCR7−CD27−CD28− EM3 increases in direct proportion to the disease severity of COVID-19

COVID-19, which emerged in December 2019 and continues to wreak havoc, has led to the death of many people around the world. In this study, we aimed to uncover the variables underlying the exacerbation of the disease by considering the changes in T cell subsets in adults and juveniles with different disease severity of COVID-19. Peripheral blood samples of 193 patients (128 adults and 65 juveniles) diagnosed with COVID-19 were evaluated in a flow cytometer, and a broad T cell profile was revealed by examining T cell subsets in terms of exhaustion and senescence. We found remarkable differences in the effector memory (EM; CD45RA⁻CCR7⁻) cell subsets of severe pneumonia cases. The frequencies of EM₂ CD4⁺ T, EM₃ CD4⁺ T, EM₃ CD8⁺ T, EM₂ DN T and EM₃ DN T cells were found to increase in severe pneumonia cases. Consistently, these cells were found in juveniles and uncomplicated adults in similar or lower proportions to healthy controls. The findings of our study provide a view of the T cell profile that may underlie differences in the course of COVID-19 cases in juveniles and adults and may provide new insights into the development of effective treatment strategies.