Defending against adversarial attacks on Covid-19 classifier: A denoiser-based approach.

Covid-19 has posed a serious threat to the existence of the human race. Early detection of the virus is vital to effectively containing the virus and treating the patients. Profound testing methods such as the Real-time reverse transcription-polymerase chain reaction (RT-PCR) test and the Rapid Antigen Test (RAT) are being used for detection, but they have their limitations. The need for early detection has led researchers to explore other testing techniques. Deep Neural Network (DNN) models have shown high potential in medical image classification and various models have been built by researchers which exhibit high accuracy for the task of Covid-19 detection using chest X-ray images. However, it is proven that DNNs are inherently susceptible to adversarial inputs, which can compromise the results of the models. In this paper, the adversarial robustness of such Covid-19 classifiers is evaluated by performing common adversarial attacks, which include the Fast Gradient Sign Method (FGSM) and Projected Gradient Descent (PGD). Using these attacks, it is found that the accuracy of the models for Covid-19 samples decreases drastically. In the medical domain, adversarial training is the most widely explored technique to defend against adversarial attacks. However, using this technique requires replacing the original model and retraining it by including adversarial samples. Another defensive technique, High-Level Representation Guided Denoiser (HGD), overcomes this limitation by employing an adversarial filter which is also transferable across models. Moreover, the HGD architecture, being suitable for high-resolution images, makes it a good candidate for medical image applications. In this paper, the HGD architecture has been evaluated as a potential defensive technique for the task of medical image analysis. Experiments carried out show an increased accuracy of up to 82% in the white box setting. However, in the black box setting, the defense completely fails to defend against adversarial samples.

Unexpected intraoperative finding of gallbladder torsion.

Gallbladder (GB) torsion or volvulus is a rare entity affecting elderly women. Only ~500 cases have been reported in the literature. Incidence is rare seen in ~1 in 365 520. A constant finding is the presence of the GB on a mobile mesentery. Torsion, or volvulus, of the GB occurs when it twists axially, with the subsequent obstruction of bile and/or blood flow. We briefly describe a 75-year-old female patient with acute abdomen and ultrasound and Computed tomography of abdomen revealed a distended GB. On laparotomy, we encountered a twisted GB with gangrene and cholecystectomy was done. GB volvulus is a rare occurrence and clinically mimic's acute cholecystitis and should be sought with high suspicion especially when encountering a thin elderly woman. Immediate diagnosis is prime as delay may be fatal. Even with recent advances in imaging, it is difficult to make a correct preoperative diagnosis of GB torsion.

Basaloid squamous cell carcinoma.

Basaloid squamous cell carcinoma (BSCC) is a rare variant of squamous cell carcinoma characterized by a conglomerate of clinically aggressive course and disparate histopathological features. It is frequently seen in upper aerodigestive tract area. Histopathologically, it is biphasic and composed of two types of tumor cells, namely basaloid and squamous cells. Tumor markers, namely, BerEp4, epithelial membrane antigen and p53 are used in this case to differentiate from similar tumors which impersonate BSCC histologically but differ prognostically. We report a case of BSCC in a 48-year-old female patient, involving the lateral border of the tongue with an exhaustive picture of its histological and immunohistochemical appearance.

Post coronavirus disease mucormycosis involving the mandible: A case report with brief note on literature.

Mucormycosis also termed as phycomycosis or zygomycosis is less commonly seen in oral cavity. However, it is an invasive, life-threatening and aggressive fungal infection. It mostly targets individuals with altered immunological system and diabetes. In this recent pandemic situation, the individuals affected with coronavirus disease 2019 (COVID-19) are also affected with this fungal infection which commonly involves the maxilla. In this case report, we present a case of a 45-year-old female affected with mucormycosis in post-COVID scenario involving mandible which is quite rare situation. The case report covers clinical findings, radiographic investigations and histopathological details with brief on literature review. Since mucormycosis is aggressive fungal infection, it should be handled with multimodal approach to reduce the systemic damage of an individual, morbidity and mortality.

Primary reinforcement with rectus abdominis muscle flap-a salvage technique for a tenuous post traumatic duodenal perforation- a case report.

INTRODUCTION: The conventional techniques for management of complex duodenal injuries are duodenal diverticularisation, pyloric exclusion or triple tube decompression. We here present a salvage technique of primary reinforcement with pedicled rectus abdominis muscle flap (RAMF) for a tenuous post traumatic duodenal perforation (PTDP). The majority of the studies in the literature are on the use RAMF for the secondary repair of peptic duodenal perforations. PRESENTATION OF CASE: A 38 year old male presented with an acute abdomen, three days after sustaining a blunt abdominal trauma. The clinical and radiological findings in the abdomen were subtle and not contributory. An emergency laparotomy with a high index of suspicion revealed a large perforation in the anterolateral wall of the second portion of the duodenum with a friable unhealthy wall and shearing of the serosa around the perforation site. The entire omentum was unhealthy, contused with areas of gangrene and omentectomy done. The perforation site was closed using 3.0 vicryl and reinforced with a pedicled right RAMF based on the superior epigastric artery. The patient recovered uneventfully and was discharged. DISCUSSION: The addition of conventional diversion techniques to primary duodenorrhaphy is sophisticated, time consuming and adds morbidity. CONCLUSION: RAMF is a good tissue substitute to buttress tenuous duodenal injuries presenting late with inflamed, friable perforation sites and associated tissue loss, where duodenorrhaphy alone may not be successful. RAMF is a valuable salvage technique when the omentum is not available and the local tissue condition negates the effectiveness of other simpler techniques.

A rare tumour of pancreas-Case report.

INTRODUCTION: Pancreatic schwannomas are very rare neoplasm arising from Schwann cells that present in the nerve sheath. Schwannoma usually occur in the extremities but can also be found in the trunk, head and neck, retroperitoneum, mediastinum, pelvis and rectum. PRESENTATION OF CASE: We briefly describe a 30-year-old female patient with upper abdominal pain and on examination by ultrasound and Computed tomography of abdomen revealed a solid tumor arising from body of the pancreas. A laparoscopic splenic vessel preserving distal pancreatectomy (kimura) was performed. DISCUSSION: Approximately only 50 cases reported in the literature and none of these cases were diagnosed as schwannoma preoperatively. CT scan is often useful to establish pancreatic lesion which usually demonstrate hypodense lesion with encapsulation CONCLUSION: Although the incidence of pancreatic schwannoma is low, it must be considered as one possibility in the differential diagnosis of mass lesions in the pancreas and whenever possible especially in large tumors surgical resections should be considered due to increased chance of transformation to malignancy.

Molecular Docking Study for Inhibitors of Aggregatibacter actinomycetamcomitans Toxins in Treatment of Aggressive Perioodontitis.

INTRODUCTION: Periodontitis is a chronic inflammatory disease of the periodontal tissues causing periodontal attachment loss and destruction of the alveolar bone which leads to mobility and loss of teeth. Aggregatibacter actinomycetemcomitans (Aa) is a gram negative, capnophilic, coccobacillus that plays an important role in aggressive Periodontitis. Aa produces a variety of virulence factors that facilitate the colonization, invasion and destruction of the periodontal tissues. Leukotoxin and cytolethal distending toxin (Cdt) are most important virulence factors of Aa. MATERIALS AND METHODS: The three dimensional structure of leukotoxin was derived by Easy modeller software and Cdt was retrieved from RCSB database. The possible binding sites of toxins were searched using binding site prediction tool Q site finder. A total of 1000 ligands of flavanol derivatives were generated with the help of software ACD chemsketch. Rapid virtual screenings of these compounds were performed in the docking tool iGEMDOCK v2.0. Based on the binding energy, six ligands were selected for the further study. The selected six ligands were then analysed for drug relevant properties based on "Lipinski's rule of five" and other drug like properties. The accurate docking of six ligands was performed using docking tool iGEMDOCK v2.0. RESULTS: From the present study, it has been found that carboxyl {(2R,3R)-3,7 dihydroxy 4-oxo-2(3,4,5-trihydroxyphenyl)-3,4-dihydro2H-chromen-5-yl} oxonium, which is a novel compound can effectively act as an inhibitor for both the toxins. CONCLUSION: The leucotoxin and cytolethal distending toxin of Aa is found to be the major virulence factors involved in the causation of aggressive periodontitis. Hence the inhibitors of these toxins can be an effective drug in treatment of aggressive periodontitis.