ABSTRACT
Background and ObjectiveBells palsy (BP) has been considered as a serious adverse event following the SARS-CoV-2 vaccination. Many studies have reported BP following vaccination, although neither a causative relationship nor a prevalence of the condition higher than the general population has been established. The outcomes of interest were to compare BP incidence among (a) SARS-CoV-2 vaccine recipients, (b) nonrecipients in the placebo or unvaccinated cohorts, (c) different types of SARS-CoV-2 vaccines, and (d) SARS-CoV-2 infected vs. SARS-CoV-2 vaccinated individuals. MethodsWe performed a systematic search through MEDLINE (via PubMed), Web of Science, Scopus, Cochrane library, and Google Scholar from the inception to August 15, 2022. We included articles reporting individuals receiving any SARS-CoV-2 vaccine in whom BP had occurred. Studies reporting facial paralysis due to etiologies other than BP were excluded. Random- and fixed-effects meta-analyses using the Mantel-Haenszel method were conducted for the quantitative synthesis. Newcastle-Ottawa scale (NOS) was used to assess the quality. The study was conducted in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline, and the protocol was registered with PROSPERO (CRD42022313299). Analyses were carried out using the R, version 4.2.1 (R package meta version 5.2-0). ResultsFifty studies were included, of which 17 entered the quantitative synthesis. First, pooling four phase-3 randomized controlled trials (RCT) indicated BP occurrence was significantly higher in SARS-CoV-2 vaccines (77, 525 doses) compared to placebo (66, 682 doses) (OR = 3.00, 95% CI = 1.10 - 8.18, I2 = 0%). Second, pooling nine observational studies of mRNA SARS-CoV-2 vaccine doses (13, 518,026) and matched unvaccinated individuals (13, 510,701) revealed no significant increase in the odds of BP in the vaccinated group compared to the unvaccinated group (OR: 0.70 (95% CI 0.42-1.16), I2=94%). The third meta-analysis suggested that post-vaccination BP among first dose Pfizer/BioNTech recipients (22,760,698) did not significantly differ from that in first dose Oxford/AstraZeneca recipients (22,978,880) (OR = 0.97, 95% CI = 0.82 - 1.15, I2 = 0%). According to the fourth meta-analysis, BP was significantly more commonly reported after SARS-CoV-2 infection (2,641,398) than after SARS-CoV-2 vaccinations (36,988,718) (RR = 4.03, 95% CI = 1.78 - 9.12, I2 = 96%). ConclusionOur meta-analysis suggests a higher incidence of BP among vaccinated vs. placebo groups. BP occurrence did not significantly differ between Pfizer/BioNTech and Oxford/AstraZeneca vaccines. SARS-CoV-2 infection posed a significantly greater risk for BP than SARS-CoV-2 vaccines.
ABSTRACT
Objective: To investigate the effects of benzene on rat's cerebellum structure and behavioral characteristics, including anxiety and motor impairment. Methods: Twenty rats were randomly allocated into two groups orally receiving distilled water and benzene (200 mg/kg/day). A total of 10 rats were used at the beginning of benzene exposure. Two rats died during benzene treatment and 8 rats remained for evaluation of the behavioral test and finally 6 rats underwent histological assessment. At the end of the 4th week, motor function and anxiety were evaluated in rotarod test and elevated plus maze, respectively. Besides, the cerebellum was dissected for structural assessment using stereological methods. Results: Performance of the benzene-treated rats in fixed and accelerating speed rotarod was impaired and their riding time (endurance) was lower compared to the control group (P = 0.02). The benzene-treated rats also spent less time in the open arms and had fewer entrances to the open arms in comparison to the control group, indicating anxiety (P = 0.01). The total volume of the cerebellar hemisphere, its cortex, intracerebellar nuclei, total number of the Purkinje, Bergmann, Golgi, granule, neurons and glial cells of the molecular layer, and neurons and glial cells of the intracerebellar nuclei were reduced by 34%-76% in the benzene-treated rats in comparison to the distilled water group (P = 0.003). The most cell loss was seen in Bergmann glia. Conclusions: The structure of cerebellum altered after benzene treatment. In addition, motor impairment and anxiety could be seen in benzene-treated rats.
ABSTRACT
Quantitative studies to date on the effects of opioid consumption and abstinence on the nervous system using modern stereological methods have not received enough attention. In addition, they have yielded controversial results. The present study was conducted to investigate the effects of morphine, with or without abstinence, on the neurons and oligodendrocytes of the medial prefrontal cortex (MPFC) in rats using quantitative stereological methods. The male rats were divided into four groups: the first (saline [SAL]) and second (morphine [MOR]) groups were treated with saline and an escalating dose of morphine (5-20 mg/kg) for 30 days, respectively; the third (SAL+abstinence [ABS]) and fourth (MOR+ABS) groups were treated in the same manner as the previous groups plus they had a 30-day abstinence period. The results showed that the volume of the MPFC and its subdivisions decreased by approximately 15% in the MOR group compared with that in the SAL group (P<0.05). In addition, the volume decreased by approximately 24% in the MOR+ABS group compared with that in the SAL+ABS group (P<0.05). The number of neurons in the MOR and MOR+ABS groups decreased by approximately 44% and 35%, respectively, compared with that in their corresponding control groups. Moreover, the number of the oligodendrocytes in the MOR and MOR+ABS groups decreased by approximately 41% and 37%, respectively. No significant difference was noted in the number of cells in the MOR and MOR+ABS groups. In conclusion, morphine consumption leads to a permanent reduction in the number of neurons and oligodendrocytes, and no additional neuron and oligodendrocyte loss occurs after abstinence.
