High-density polyethylene (HDPE)-incorporated boron carbide and boric acid nanoparticles as a nanoshield of photoneutrons from medical linear accelerators.

PURPOSE: The current study aimed to investigate boron carbide and boric acid nanoparticles (NPs) as absorbents for thermal neutrons and high-density polyethylene (HDPE) as a substrate and neutron moderator for fast neutrons. The goal was to assess the performance of boron carbide and boric acid NPs based on HDPE as a nanoshield of photoneutrons from medical linear accelerators. MATERIALS AND METHODS: This study was conducted in two parts of simulation and practice. The Monte Carlo (MC) simulation involved modeling and verification of the single-layer, double-layer, and combined nanoshields by selecting nanomaterials and substrates and, finally, calculating the macroscopic cross-sections. The practical part involved manufacturing nanoshields based on the simulation results and evaluating the manufactured nanocomposites via experimental measurements. RESULTS: MC simulation results with an uncertainty of less than 1% showed that for the monolayer samples, the best result belonged to boron carbide at a concentration of 10% and a macroscopic cross-section of 0.933 cm-1. At a concentration of 20%, the highest value among the double-layer samples was 0.936 cm-1 and for the combined samples, this value was 0.928 cm-1. Boron carbide single-layer nanocomposites at a 10% concentration, as well as the bilayer nanoshield of 10% boron carbide and 20% boric acid performed well; however, the best performance belonged to the nanoshield with a macroscopic cross-section of 0.960 and the combination containing 5% boron carbide and 10% boric acid. CONCLUSIONS: The research suggests that utilizing boron carbide and boric acid nanoshields in combination with HDPE holds promise as a viable approach to protecting from the photoneutrons. Further exploration of these nanocomposite shields and their practical applications is warranted, with the potential to yield significant advancements in radiation therapy safety and efficacy.

Why the COVID-19 Is Not Significantly Reduced in Iran?

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was transported from China to Iran via passengers. The virus is transmitted through droplets from coughing, sneezing, talking and contact with infected surfaces. Due to high transmissibility in places such as clinics, medical offices, buses and offices where there are large crowds, it spread rapidly in Iran and caused the mortality of a significant number of people, especially the elderly with underlying disease. Preventing travel and gatherings, as well as applying house quarantine in Apr 2020, reduced COVID-19 somewhat but then due to lack of attention to social distancing, reducing the use of masks by the people and inappropriate decisions by the national committee on combating coronavirus (NCCC), including reducing the working hours of public offices and shops, reducing the staff of government offices, monopoly on the distribution of essential materials and supplies, the presence of overcrowding in clinics of medical centers, hospitals, and private clinics caused the decline of the disease in the country to decrease. Measures can be taken to prevent the spread of the virus as much as possible, including: rapid detection of infected people, their isolation, contact tracing, quarantine of people over 65 and under 15, protection of the elderly, prevention of gatherings, forcing the use of protective equipment in possible gatherings, and electronicizing public services.

IFN-γ and TNF-α Gene Polymorphisms in Multiple Sclerosis Patients in Northwest Iran.

BACKGROUND: Cytokines are polypeptides that play critical roles in immune responses. Gene polymorphisms occurring in the inflammatory cytokines are taking a role in autoimmune diseases, including multiple sclerosis (MS), which may induce inappropriate immune responses. OBJECTIVE: The aim of this study was to investigate the allelic and genotypic frequencies of interferon gamma gene (IFN-γ) at +874A/T locus and tumor necrosis factor (TNF-α) at+308A/G locus in MS patients of Azeri population. METHODS: At first, a questionnaire was prepared for each of 240 healthy, non-relative, and 152 Azeri MS patients before obtaining the blood sample from all subjects. After DNA extraction, the frequency of alleles and genotypes of the IFN-γ and TNF-α genes at +874A/T and -308G/A loci, respectively, were determined by allele-specific PCR method. Finally, the frequencies were compared between control and MS patients by chi-square test (x2-test) and p<0.05 was considered significant. RESULTS: In the IFN-γ +874A/T gene single nucleotide polymorphism (SNP), the most allelic and genotypic frequencies in MS patients were the A allele, 55.26% (p=0.04) and the AT genotype, 52.63% (p=0.048). In healthy individuals, it was 65.42% for the A allele and 45.42% for the AA genotype. For the TNF-α 308 G/A SNP, the highest allelic and genotypic frequencies in MS patients were the G allele with 55.92% (p<0.001) and AG genotype with 61.84%, and in healthy subjects, the allelic and genotypic frequencies were 84.2% and 70.8% for the G allele and GG genotype, respectively. CONCLUSION: Head trauma, the infection with the herpes virus and Mycoplasma pneumonia, frequent colds and high consumption of canned foods provide grounds for MS. The T allele in the IFN-γ gene (+874) and the genotypes of AA and AG at the TNF-α gene (-308) at the position-308 were considered as potential risk factors for MS. Therefore, the polymorphisms in cytokine genes and following changes in their expression levels can be effective in susceptibility to MS.

Vitamin D Receptor Gene Polymorphism and the Risk of Multiple Sclerosis in the Azeri Population of Iran.

BACKGROUND: Multiple sclerosis (MS), a disease of the central nervous system (CNS), is associated with damage to the myelin sheath of neurons. It is demonstrated that vitamin D deficiency plays an important role in the development of the disease. Binding of vitamin D to its specific nuclear receptors is a way to exert its function. OBJECTIVE: Possible correlation between the vitamin D receptor (VDR) gene and MS was evaluated in the Azeri population of Iran. METHODS: Different genotypes of the Bsml site were determined by using the PCR-RFLP method in 148 MS patients and 220 non-relative healthy controls. RESULTS: In MS patients, genotype bb was significantly higher than the healthy controls (p<0.05). Additionally, most subjects of the MS group had been insufficiently exposed to sunlight before the age of 15 (p<0.001). Our findings indicated that the red meat intake in MS patients was significantly higher than the healthy controls (p<0.001). In addition, the healthy controls had appropriate dieting behaviors in comparison to MS patients (excessive intake of some foods) (p=0.0001). CONCLUSION: In conclusion, genotype BB and sufficient exposure to sunlight before the age of 15 were the protective factors against MS. Although, excessive consumption of red meat and inappropriate dieting behaviors were predisposing factors to MS disease.

Risk Factors for COVID-19.

SARS-CoV-2 in bats was transmitted to humans at a live and wet animal market in China through the intermediate host, creating COVID-19. Viral, environmental and host factors play roles in virus infection and disease. The virus has high transmissibility and is rapidly transmitted to people through close contact and droplets from coughing, sneezing and talking loudly, as well as through contact with contaminated objects. As crowding is an environmental risk factor for contamination, its transmission is high among patients and staff in hospital and also in elderly-care centers. It is more common in the elderly, in men, and subjects with diabetes mellitus, hypertension, cardiovascular disease, and malignancy.

Tuberculosis and Diabetes Mellitus in Northwest of Iran.

BACKGROUND: Planning for control of tuberculosis would need to screen and identify individuals susceptible to TB. Due to the weakness of immune system in diabetic patients, it is more likely for them to reactivate latent TB infection. Regarding the increasing number of diabetics in the community, in this study efforts have been made to estimate the frequency of individuals who have tuberculosis and diabetes mellitus (TB-DM) simultaneously, as it could help making preventive decisions to reduce TB in this part of Iran. MATERIALS AND METHODS: In this study, 329 cases of confirmed TB patients were divided into two groups of diabetic and non-diabetic, then demographic information and clinical variables have been compared between the two groups. RESULTS: Among the examined subjects, 47 patients (14.29 %) had suffered from diabetes mellitus and tuberculosis. All of the DM patients had pulmonary tuberculosis and 87.23% of them were over the age of 50. CONCLUSION: Majority of DM-TB patients were over 50 years of age and also more than half of them were women. So it seems that for DM women over the age of 50, to detect tuberculosis, screening tests such as PPD may be necessary.

Association of Interleukin-1 and Inteleukin-1 Receptor Antagonist Gene Polymorphisms with Multiple Sclerosis in Azeri Population of Iran.

BACKGROUND: Cytokines as important mediators have a critical role in appropriate immune responses, the irregular production of which can lead to Multiple Sclerosis (MS). Proinflammatory cytokine interleukin-1 (IL-1) triggers inflammatory responses. Function and production of the cytokine are influenced by IL-1 coding gene polymorphism and those antagonists gene polymorphism. OBJECTIVE: The aim of the present study was to evaluate the possible correlation between MS and IL-1 related alleles in Azeri population of Iran. METHODS: Variable number tandem repeats (VNTR) genotypes of 150 MS patients and 220 healthy non-relative controls were determined. RESULTS: In the healthy controls, genotype TT at IL-1A (-889) location was significantly higher than the MS patients (p=0.0001). However, a significant difference was not found between the two groups in genotypic/allelic frequency at IL- 1B+ 3953 location. Evaluation of the IL-1RA gene revealed that genotype 1/2, and genotype 1/3 were significantly higher in the healthy controls and MS patients, respectively. Our findings indicated that the consumption of fast-food in MS patients was significantly higher than controls (p= <0.05). Also, a considerable number of MS patients had inappropriate dieting behaviors such as not eating breakfast (p= 0.0001), and irregular eating habits (p= 0.0001). CONCLUSION: Polymorphisms of the IL-1B genes and common alleles of IL-1RA were not considered as risk factors for MS disease. However, genotype TT at IL-1A (-889) location and the rare allele of IL-1RA3 can be a potential risk factor for the disease. Furthermore, inappropriate dieting behaviors and consumption of fast-food can increase the risk of MS.

False-Positive Mycobacterium tuberculosis Detection: Ways to Prevent Cross-Contamination.

The gold standard method for diagnosis of tuberculosis is the isolation of Mycobacterium tuberculosis through culture, but there is a probability of cross-contamination in simultaneous cultures of samples causing false-positives. This can result in delayed treatment of the underlying disease and drug side effects. In this paper, we reviewed studies on falsepositive cultures of M. tuberculosis. Rate of occurrence, effective factors, and extent of false-positives were analyzed. Ways to identify and reduce the false-positives and management of them are critical for all laboratories. In most cases, falsepositive is occurring in cases with only one positive culture but negative direct smear. The three most crucial factors in this regard are inappropriate technician function, contamination of reagents, and aerosol production. Thus, to reduce false-positives, good laboratory practice, as well as use of whole-genome sequencing or genotyping of all positive culture samples with a robust, extra pure method and rapid response, are essential for minimizing the rate of false-positives. Indeed, molecular approaches and epidemiological surveillance can provide a valuable tool besides culture to identify possible false positives.