Antisecretory Effect of Hydrogen Sulfide on Gastric Acid Secretion and the Involvement of Nitric Oxide

The present study was designed to investigate the effect of H2S on distention-induced gastric acid secretion. Fifty-two rats were randomly assigned to seven experimental groups. The gastric acid secretion was stimulated by gastric distention. Two groups of rats received L-cysteine or saline for 5 days before stimulation of the gastric acid secretion. Two groups of animals also received NaHS or saline just prior to stimulation of the gastric acid secretion. The effect of L-NAME and propargylglycine was also investigated. The mucosal levels of the gene expression of cyclooxygenase-2 (COX-2), endothelial nitric oxide synthase (eNOS), and H+/K+-ATPase α-subunit were quantified by qPCR and luminal concentrations of NO were determined. NaHS and L-cysteine decreased the gastric acid output in response to distention. The mRNA expression of H+/K+-ATPase α-subunit decreased by NaHS and L-cysteine as compared with the control group while gene expression of eNOS and COX-2 was upregulated. The inhibitory effect of NaHS on distention-induced gastric acid secretion was mitigated by pretreatment of L-NAME. These findings suggest the involvement of NO in mediating the antisecretory effect of H2S

نقش عوامل محیطی در انتقال ویروس SARS- CoV- 2 و راهکارهای کاهش آن

Background and Aims: Limited knowledge about SARS-CoV-2 transmission mechanism and the affecting factors is a global challenge. Due to the high prevalence of Covid-19 pandemic, airborne transmission of SARS-CoV-2 is more important than other modes of transmission. To investigate the airborne transmission of this virus, indoor air sampling was performed in COVID-19 ward of Sina Hospital in Ahvaz. Materials and Methods: Air samples were collected from two sampling points with a distance of less than or equal to 1 meter from the patient bed (in the patient's room) and more than 3 meters from the patient bed (in the corridor and the nurse station) Sampling was conducted through both active and passive methods. The collected samples were then transferred to the laboratory in the cold chain, where they were tested for the presence or absence of virus by reverse transcription polymerase chain reaction (RT-PCR). Ethical considerations were observed in all stages of the study. Results: Of the total air samples collected in our study, (21 samples), 9.52 % of the samples (2 samples) were positive for SARS-CoV-2, both of which were positive in the patient's room and were obtained by active air sampling method. Also, multivariate analysis showed that among the studied parameters, the highest correlation was found between the presence of virus in air samples and temperature, relative humidity, and concentration of particles in the air. Conclusion: The results indicate the presence of SARS-CoV-2 bioaerosols in the air inside the hospital.زمينه و اهداف: دانش محدود در مورد مکانیسم انتقال ویروس SARS-CoV-2 و عوامل تاثیر گذار بر آن یک چالش در مقیاس جهانی است. با توجه به شیوع بالای اپیدمی کووید-19، انتقال هوایی ویروس نسبت به دیگر راه‌های انتقال مورد توجه بیشتر می‌باشد. بنابراین در این مطالعه به بررسی نقش انتقال هوایی این ویروس، نمونه برداری از هوای داخلی بخش بستری بیماران کرونایی بیمارستان سینا اهواز انجام شد. مواد و روش‌ها: در هر یک از محل­های نمونه برداری، از دو نقطه با فاصله‌ی کمتر یا مساوی 1 متر از تخت بیماران (در اتاق بیماران) و فاصله بیش از 3 متر از تخت بیماران (در راهرو و ایستگاه پرستار) نمونه هوا به دو روش فعال و غیر فعال جمع آوری و در زنجیره‌ی سرما به آزمایشگاه منتقل شد. سپس با استفاده از واکنش زنجیره‌ای پلیمراز رونویسی معکوس (RT- PCR) برای حضور یا عدم حضور ویروس مورد بررسی قرار گرفتند. در تمام مراحل، ملاحظات اخلاقی مد نظر قرار گرفت.  يافته‌ها: از کل نمونه‌های هوای (21 نمونه) جمع‌آوری‌ شده برای حضور ویروس SARS-CoV-2، 52/9% نمونه‌ها (2 نمونه) مثبت شدند که هر 2 نمونه مثبت در اتاق بیماران و توسط روش نمونه­برداری فعال هوا ثبت شدند. تجزیه و تحلیل چند متغیره نشان داد که از بین پارامترهای مورد مطالعه، بیشترین همبستگی بین حضور ویروس در نمونه‌های هوا با دما، رطوبت نسبی، غلظت ذرات موجود در هوا به دست آمد. نتيجه‌گيري: تحقیق بیانگر وجود بیوآئروسل‌های SARS-CoV-2 در هوای داخل بیمارستان می‌باشد