Enhancing Medical Students' Knowledge and Performance in Otolaryngology Rotation through Combining Microlearning and Task-Based Learning Strategies

Microlearning is recommended to be implemented within the context of a wider teaching-learning ecosystem, especially in real working environments. Task-based learning is used in clinical education setting. This study aims at assessing the effect of an integrated approach of microlearning with task-based learning on medical students' knowledge and performance in Ear, Nose and Throat clerkship rotation. A total of 59 final-year medical students participated in this quasi-experimental study which included two control groups (routine teaching and task-based learning methods) and one intervention group (combined microlearning and task-based learning method). Pre- and post-tests of students' knowledge and performance were assessed through a multiple-choice question test and a Direct Observation Procedural Skills (DOPS) instrument, respectively. Performing Analysis of Covariance for knowledge post-test scores among three groups revealed significant differences (F = 3.423, p-value = 0.040) and the intervention group had the highest score. Analyzing DOPS results showed that the intervention group achieved significantly higher scores compared to the control ones for all the expected tasks (p-values = 0.001). The findings of the present study show that the combined strategy of microlearning with task-based learning is an effective clinical teaching method for enhancing medical students' knowledge and performance in a real working environment.

A study of efficacy of nigella sativa in treatment of Meniere's disease: A randomized, placebo controlled clinical trial

Purpose

Meniere's disease (MD), first introduced by Prosper Meniere, is characterized mainly by vertigo, tinnitus, aural fullness and sensorineural hearing loss. Though the exact pathophysiology of MD is unknown, immunologic and inflammatory interactions are possible underlying mechanisms involved in MD. This study is aimed to investigate the immunomodulatory and anti-inflammatory effect of Nigella sativa on MD as a therapeutic agent.

Methods

We divided 40 patients with definite MD into two groups of 20 cases. The study group received 1 g of Nigella sativa oil daily for three months and the control group received a placebo. Changes in hearing, tinnitus and vertigo were estimated by pure tone audiometry, tinnitus handicap inventory questionnaire and dizziness handicap inventory questionnaire, respectively.

Results

At the end of the study we did not observe any significant improvement in study's group hearing threshold, tinnitus and vertigo compared to the control group.

Conclusions

In this study, statistical analysis showed that Nigella sativa failed to improve signs and symptoms of MD. However, further investigations with a larger study population are needed to ascertain the current conclusion.

Inflammatory Myofibroblastic Tumor: Two Cases in Head and Neck Region

Previously described as inflammatory pseudotumor, inflammatory myofibroblastic tumors (IMT) are now considered as distinct tumors of specific histopathologic features. This rare mesenchymal tumor consists of spindle shaped fibroblasts associated with various amounts of inflammatory cells. Head and neck region, is an unusual site of involvement. In this article, we will introduce two separate cases with the diagnosis of IMT involving the nasopharynx and the temporal bone which are both rare locations of presentation. Inflammatory myofibroblastic tumor should be considered in the differential diagnosis list of every mass in head and neck region.

Metabotropic glutamate receptor: A new possible therapeutic target for cochlear synaptopathy

Objectives

Cochlear synaptopathy is a common cause of auditory disorders in which glutamate over-activation occurs. Modulating glutamatergic pathways has been proposed to down-regulate post-synaptic excitation.

Materials and Methods

12-guinea pigs as sham and test groups were exposed to a 4-kHz noise at 104 dB SPL, for 2 hr. Pre-exposure intra-tympanic injection with LY354740 and normal saline 9% was applied in the test and sham groups. The amplitude growth of ABR-wave-I and wave-III latency shift with noise were considered in pre- and post-exposure times. The synapses were observed by transmission electron-microscopy.

Results

ABR thresholds recovered 1-week post-exposure in both groups. The reduction of wave-I amplitude at 4, 6, and 8 kHz were statistically different between pre- and 1- day post-exposure and recovered mostly in the sham group. The amount of latency shift in masked ABR was different between pre- and all post-exposure, and the response could not be detected at higher than 50 dB SL noise. However, the response detectability increased to 60 dB SL noise, and the significance of differences between pre- and post-exposure persisted only at the high level of noise in the test group. In electron-microscopy of sham samples, the size of the ribbon was larger, spherical with an irregularity, and hollow. The post-synaptic density was thicker and missed its flat orientation.

Conclusion

The higher slope of the ABR-wave I amplitude, the more tolerance of noise in masked ABR, concomitant with the histological finding that revealed less synaptic damage, confirmed the therapeutic effect of LY354740 in cochlear synaptopathy.

The coronavirus disease 2019: the prevalence, prognosis, and recovery from olfactory dysfunction (OD)

Background

Many patients with coronavirus disease 2019 (COVID-19) complain from olfactory dysfunction (OD).

Aims/objectives: To evaluate the prevalence, prognosis, and recovery from OD in COVID-19 patients.

Material and methods

In this study, patients with COVID-19 symptoms who were referred to six different tertiary referral centres were recruited after positive results for COVID-19. All patients were assessed for a one-month follow-up after the initial diagnosis of COVID-19.

Results

Three hundred and eleven patients with COVID-19 were recruited in the present study. Two hundred and seven patients (66.6%) had a recent history of OD. One hundred and seventy-eight patients had experienced OD as a primary symptom intercurrent to other COVID-19 symptoms or solely. Sixty-nine patients had OD at the time of presentation to referral centres. Headache and nasal obstruction had significant relationships with recovery from OD in this subgroup, and the platelet count was the most important predictor for the recovery from OD.

One hundred seventy-nine (86.4%) patients were nearly or fully recovered from OD approximately a month after the onset of OD.

Conclusion

Headache, nasal obstruction, and platelet count may have specific roles as prognostic factors in the recovery from OD.

Comparison of functional outcomes of cartilage tympanoplasty with silastic sheet versus Gelfoam packing in middle ear

BACKGROUND AND AIM

Tympanoplasty is a common surgery in otorhinolaryngology field. In majority of procedures, in addition to the graft used for closure of tympanic membrane, a packing material is essential to be placed in the middle ear cavity. The main goals of packing can be summarized as providing support to the tympanic membrane and ossicular grafts, aeration of middle ear cavity and hemostasis. Several packing materials are currently available for using in middle ear surgeries. Each agent is associated with particular advantages and disadvantages, so choosing the proper packing agent is essential in tympanoplasty surgeries. In this study we aimed to compare two common packing materials (Gelfoam and silastic sheets) in cartilage tympanoplasty surgeries.

METHODS AND MATERIALS

In this block-randomized clinical trial, 78 patients undergoing tympanoplasty in Vali-e-asr hospital in 2017 and 2018 were enrolled. They were randomly assigned to silastic sheet or gelfoam groups. The functional outcomes were compared between the groups. Statistical analysis was performed by SPSS.

RESULTS

Success was achieved in 32 (82.1%) patients and 34 (87.2%) patients in gelfoam and silastic sheets' groups, respectively (p = 0.530). The perforation area percentage was significantly lower (P = 0.007) in Gelfoam group. The other parameters were statistically the same in both groups (P > 0.05).

CONCLUSION

Overall, Gelfoam and silastic sheet methods had similar efficacy in cartilage tympanoplasty. Using each method depends on the preferrence of surgeon and patients' characteristics. Multi-center studies with larger sample sizes are needed for more conclusive results.

The first successful application of preimplantation genetic diagnosis for hearing loss in Iran

Hearing impairment (HI) caused by mutations in the connexin-26 gene (GJB2) accounts for the majority of cases with inherited, nonsyndromic sensorineural hearing loss. Due to the illegality of the abortion of deaf fetuses in Islamic countries, preimplantation genetic diagnosis (PGD) is a possible solution for afflicted families to have a healthy offspring. This study describes the first use of PGD for GJB2 associated non-syndromic deafness in Iran. GJB2 donor splicing site IVS1+1G>A mutation analysis was performed using Sanger sequencing for a total of 71 Iranian families with at least 1 deaf child diagnosed with non-syndromic deafness. In Vitro Fertilization (IVF) was performed, followed by PGD for a cousin couple with a 50% chance of having an affected child. Bi-allelic pathogenic mutations were found in a total of 12 families (~17 %); of which a couple was a PGD volunteer. The deaf woman in this family was homozygous and her husband was a carrier of the IVS1+1G>A gene mutation. Among 8 biopsied embryos, two healthy embryos were implanted which resulted in a single pregnancy and subsequent birth of a healthy baby boy. This is the first report of a successful application of PGD for hearing loss in Iran. Having a baby with a severe hearing impairment often imposes families with long-term disease burden and heavy therapy costs. Today PGD has provided an opportunity for high-risk individuals to avoid the birth of a deaf child.

The first successful application of preimplantation genetic diagnosis for hearing loss in Iran

Hearing impairment (HI) caused by mutations in the connexin-26 gene (GJB2) accounts for the majority of cases with inherited, nonsyndromic sensorineural hearing loss. Due to the illegality of the abortion of deaf fetuses in Islamic countries, preimplantation genetic diagnosis (PGD) is a possible solution for afflicted families to have a healthy offspring. This study describes the first use of PGD for GJB2 associated non-syndromic deafness in Iran. GJB2 donor splicing site IVS1+1G>A mutation analysis was performed using Sanger sequencing for a total of 71 Iranian families with at least 1 deaf child diagnosed with non-syndromic deafness. In Vitro Fertilization (IVF) was performed, followed by PGD for a cousin couple with a 50% chance of having an affected child. Bi-allelic pathogenic mutations were found in a total of 12 families (~17 %); of which a couple was a PGD volunteer. The deaf woman in this family was homozygous and her husband was a carrier of the IVS1+1G>A gene mutation. Among 8 biopsied embryos, two healthy embryos were implanted which resulted in a single pregnancy and subsequent birth of a healthy baby boy. This is the first report of a successful application of PGD for hearing loss in Iran. Having a baby with a severe hearing impairment often imposes families with long-term disease burden and heavy therapy costs. Today PGD has provided an opportunity for high-risk individuals to avoid the birth of a deaf child.

Conservative versus Surgical Therapy in Managing Patients with Facial Nerve Palsy Due to the Temporal Bone Fracture

Facial nerve paralysis is classified into immediate or delayed-onset palsy, and affected patients should be treated through conservative or surgical therapy. Appropriate treatment is somewhat debated as well as proper time for performing surgery. This study aimed to assess treatment outcome between conservatively and surgically treated groups and to determine the appropriate time of surgery in selected patients for surgery. Twenty-four patients from April 2008 to July 2015 were included. Performing decompression surgery within the first 2 months following the trauma accompanies a better prognosis ( p -value < 0.05). Eleven patients were managed conservatively, and 4 of them demonstrated immediate onset and 7 indicated delayed onset. Nine patients obtained normal nerve function, one patient had partial palsy, and one of them had complete palsy. There was no significant difference in the rate of recovery between types of the treatment ( p -value > 0.05). Decompression surgery is recommended in the first 2 months after the trauma for immediate onset and also complete degeneration on electroneuronography.

Metabolic profiling of valproic acid by cDNA-expressed human cytochrome P450 enzymes using negative-ion chemical ionization gas chromatography-mass spectrometry

A sensitive negative ion chemical ionization (NCI) gas chromatographic-mass spectrometric (GC-MS) method was modified for the quantitation of valproic acid (VPA) metabolites generated from in vitro cDNA-expressed human microsomal cytochrome P450 incubations. The use of the inherent soft ionization nature of electron-capture NCI to achieve high sensitivity enabled us to conduct kinetic studies using small amounts of recombinant human P450 enzymes. The assay is based on the selective ion monitoring of the intense [M-181] fragments of pentafluorobenzyl (PFB) esters in the NCI mode, and has the following features: (1) a micro-extraction procedure to isolate VPA metabolites from small incubation volumes (100 microl); (2) a second step derivatization with tert.-butyldimethylsilylating reagents to enhance sensitivity for hydroxylated metabolites; (3) a short run-time (<30 min) while maintaining full separation of 15 VPA metabolites by using a narrow-bore non-polar DB-1 column plus a new temperature gradient; and (4) good reproducibility and accuracy (intra- and inter-assay RSDs <15%, bias <15%) by using seven deuterated derivatives of analytes as internal standards. The derivatives of mono-and diunsaturated metabolites, like the parent drug, produced abundant [M-181](-) ions while the hydroxylated metabolites gave an ion at m/z of 273, corresponding to the [M-181](-) ion of the tert.-butyldimethylsilyl ethers. In conclusion, the GC-NCI-MS analysis of valproate metabolites provided us with a high resolution and sensitivity necessary to conduct metabolic and kinetic studies of valproic acid in small volume samples typical of the in vitro cDNA-expressed micro-incubation enzymatic systems.

Cytochrome P450 dependent xenobiotic activation by physiological hydroperoxides in intact hepatocytes

Xenobiotic metabolic activation by intact hepatocytes was recently shown to be enhanced by the addition of nontoxic concentrations of t-butyl hydroperoxide and prevented by cytochrome P450 inhibitors. Furthermore, H2O2 (Km = 103 microM) was found to be highly effective in supporting the human microsomal CYP1A2 catalyzed metabolic activation of the heterocyclic aromatic amine 2-amino-3-methylimidazo (4,5-f) quinoline (IQ) to mutagenic metabolites and the DNA adduct formed was the same as that formed by the mixed-function oxidase catalyzed activation system. In the following, it is shown that the cytotoxicity of other xenobiotics including carcinogenic arylamines and their N-hydroxyarylamine metabolites were markedly enhanced by hydroperoxide addition but not in the presence of cytochrome P450 inhibitors. The CYP1A2 dependent O-demethylation of methoxyresorufin in 3-methylcholanthrene induced hepatocytes was also markedly enhanced when intracellular H2O2 was generated by the mitochondrial monoamine oxidase (MAO) substrates tyramine or kynurenamine. Linoleic acid hydroperoxide also dramatically enhanced the cytotoxicity of phenelzine towards isolated hepatocytes and the microsomal metabolism of phenelzine to form ethylbenzene. The P450 inhibitors phenylimidazole, benzylimidazole prevented the metabolic activation of phenelzine but not lipid peroxidation. These results suggest that linoleic acid hydroperoxide can activate hydrazines via a cytochrome P450 peroxidase catalyzed one electron oxidation to form highly cytotoxic reactive intermediates. Furthermore, increased hydrogen peroxide formation, e.g. as a result of oxidative stress, would also be expected to enhance the metabolic activation of carcinogenic arylamines via the peroxygenase function of CYP1A2.

Hydrogen peroxide supports human and rat cytochrome P450 1A2-catalyzed 2-amino-3-methylimidazo[4,5-f]quinoline bioactivation to mutagenic metabolites: significance of cytochrome P450 peroxygenase

We show that the naturally occurring hydroperoxide hydrogen peroxide is highly effective in supporting the cytochrome P450 1A2 peroxygenase-catalyzed metabolic activation of the heterocyclic aromatic amine 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) to genotoxic metabolites. Mutagenicity was assessed by the Ames assay with Salmonella typhimurium strain YG1012 and an activation system consisting of hydroperoxides plus either 3-methylcholanthrene-induced rat liver microsomes (rP4501A) or human P450 1A2-containing microsomes (hP4501A2). The mutagenic response was dependent on the concentration of microsomal protein, IQ, and hydroperoxides. The addition of hydrogen peroxide or tert-butyl hydroperoxide to rP4501A greatly enhanced the yield of histidine prototrophic (His+) revertants. This increase was inhibited, in a concentration-dependent manner, by alpha-naphthoflavone, a P450 1A inhibitor. Hydrogen peroxide was the most effective peroxygenase cofactor, particularly with hP4501A2 (K(m) = 0.1 mM). The hydroperoxide-supported activation of IQ produced reactive intermediates which bound to 2'-deoxyguanosine; LC/MS analysis of the adducts revealed the same major (protonated) adduct at m/z = 464.4 as previously reported for the DNA adduct formed (in vivo or in vitro) by the mixed function-catalyzed bioactivation system. None of the peroxidase-catalyzed IQ metabolites (nitro-, azo-, or azoxy-IQ) were detected. In conclusion, hydrogen peroxide in the physiological/pathological concentration range may be able to support the metabolic activation of arylamines to genotoxic products through the cytochrome P450 peroxygenase pathway.

The involvement of cytochrome P450 peroxidase in the metabolic bioactivation of cumene hydroperoxide by isolated rat hepatocytes

Organic hydroperoxides are believed to be primarily detoxified in cells by the GSH peroxidase/GSSG reductase system and activated to cytotoxic radical species by non-heme iron. However, organic hydroperoxides seem to be bioactivated by cytochrome P450 (P450) in isolated hepatocytes as various P450 (particularly P450 2E1) inhibitors inhibited cumene hydroperoxide (CumOOH) metabolism and attenuated subsequent cytotoxic effects including antimycin A-resistant respiration, lipid peroxidation, iron mobilization, ATP depletion, and cell membrane disruption. CumOOH metabolism was also faster in P450 1A-induced hepatocytes and was inhibited by the P450 1A inhibitor alpha-naphthoflavone. The ferric chelator deferoxamine also prevented cytotoxicity even after CumOOH had been metabolized but had no effect on CumOOH metabolism. This emphasizes the toxicological significance of the iron released following hydroperoxide metabolic activation by cytochrome P450. The radical trap, 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO), had no effect on CumOOH metabolism but prevented CumOOH-induced antimycin A-resistant respiration, lipid peroxidation, iron mobilization, and loss of membrane integrity. These results suggest that CumOOH is metabolically activated by some P450 enzymes (e.g., P450 2E1) in hepatocytes to form reactive radical metabolites or oxidants that cause lipid peroxidation and cytotoxicity.

Cytochrome P450 peroxidase/peroxygenase mediated xenobiotic metabolic activation and cytotoxicity in isolated hepatocytes

Cytochrome P450 (P450) can utilize organic hydroperoxides and peracids to support hydroxylation and dealkylation of various P450 substrates. However, the biological significance of this P450 peroxygenase/peroxidase activity in the bioactivation of xenobiotics in intact cells has not been demonstrated. We have shown that tert-butyl hydroperoxide (tBHP) markedly enhances 3-20-fold the cytotoxicity of various aromatic hydrocarbons and their phenolic metabolites. The tBHP-enhanced hepatocyte cytotoxicity of 4-nitroanisole (4-NA) and 4-hydroxyanisole (4-HA) was also accompanied by an increase in the hepatocyte O-demethylation of 4-NA and 4-HA up to 7.5- and 21-fold, respectively. Hepatocyte GSH conjugation by 4-HA was also markedly increased by tBHP. An LC/MS analysis of the GSH conjugates identified hydroquinone-GSH and 4-methoxy-catechol:GSH conjugates as the predominant adducts. Pretreatment of hepatocytes with P450 inhibitors, e.g., phenylimidazole, prevented tBHP-enhanced 4-HA metabolism, GSH depletion, and cytotoxicity. In conclusion, hydroperoxides can therefore be used by intact cells to support the bioactivation of xenobiotics through the P450 peroxidase/peroxygenase system.

The duration of induction and species influences the downregulation of cytochrome P450 by the interferon inducer polyinosinic acid-polycytidylic acid

Interferon (IFN) has long been recognized to downregulate cytochrome P450-mediated drug metabolism. Some investigations have shown that induced P450 enzymes tend to be more resistant to the depressant effect of IFN, whereas constitutive forms of P450 are uniformly depressed by IFN. We examined the effect of varying the period of induction of P450 proteins (CYP1A1, CYP2B, and CYP2E1) in two animal species. In mice, the IFN inducer polyinosinic acid-polycytidylic acid depressed the constitutive and induced enzyme activities of ethoxyresorufin O-deethylase, benzyl-oxyresorufin O-dealkylase, and p-nitrophenol hydroxylase at all levels of induction. The depression of P450 proteins (CYP1A1, CYP2B10, and CYP2E1) was confirmed by immunoblotting. In contrast, the downregulation of the same enzyme activities observed at 0 and 24 hr of induction did not occur after 48 or 72 hr of induction in the rat. Immunoblotting confirmed that CYP1A1, CYP2B1, and CYP2E1 levels were downregulated in control and at low levels of induction, but were not affected at high levels of induction. The response of constitutive enzyme activities to downregulation by IFN was not influenced by any of the induction protocols in rats or mice. Thus, cytochrome P450 induction does not invariably confer resistance to IFN-mediated downregulation of the enzymes, and the mechanism of induction does not determine the response to IFN. It seems that the species and duration or level of induction are the major influences on the observed response of P450 enzymes to IFN-evoked downregulation.

Modulatory effect of hyperthermia on hepatic microsomal cytochrome P450 in mice

It is widely known that the clearance of drugs is often compromised during episodes of infectious disease via a down-regulation of cytochrome P450 (P450) at a pre-translational step in enzyme synthesis. Etiocholanolone (ETC), a potent inflammatory agent, induces fever in humans and causes a decrease in the clearance of certain drugs that are metabolized by P450. On this basis it is widely believed that the fever per se rather than the immune modulation that occurs during infections may have a major role in depression of microsomal P450 enzymes during viral infections in humans. In the present study, we demonstrated that although ETC did not induce hyperthermia in mice, it still evoked a depression of the levels of P450 in hepatic microsomes. Ethoxyresorufin O-deethylase (EROD) was also inhibited significantly when hepatic microsomes were incubated with various concentrations of ETC in vitro. P450 levels and EROD activities remained unchanged following hyperthermia that was induced by a non-inflammatory procedure using 2,4-dinitrophenol. Provided the response in rodents is similar to humans, these results indicate that the depression of drug biotransformation by ETC in humans is more likely to be caused by the direct effects of this agent or other mechanisms rather than by the fever it produces. This may suggest that the loss of drug metabolism in humans during infections is due to the activation of host defence responses rather than to the febrile nature of the illness.