Sequence self-selection by cyclic phase separation

The emergence of functional oligonucleotides on early Earth required a molecular selection mechanism to screen for specific sequences with prebiotic functions. Cyclic processes such as daily temperature oscillations were ubiquitous in this environment and could trigger oligonucleotide phase separation. Here, we propose sequence selection based on phase separation cycles realized through sedimentation in a system subjected to the feeding of oligonucleotides. Using theory and experiments with DNA, we show sequence-specific enrichment in the sedimented dense phase, in particular of short 22-mer DNA sequences. The underlying mechanism selects for complementarity, as it enriches sequences that tightly interact in the dense phase through base-pairing. Our mechanism also enables initially weakly biased pools to enhance their sequence bias or to replace the previously most abundant sequences as the cycles progress. Our findings provide an example of a selection mechanism that may have eased screening for auto-catalytic self-replicating oligonucleotides.

Non-Hodgkin Lymphoma Presenting with Recurrent Pleural Effusion: A Rare Case Report

Non-Hodgkin lymphoma (NHL) is a type of carcinoma which usually begins with lymph nodes. Pathogenesis of pleural fluid formation and reabsorption is also associated with pulmonary lymphatic system. Usually pleural effusions are encountered as complications due to infective aetiologies and non-infective causes. Pleural fluid formation and reabsorption in pulmonary lymphatic system are associated with pathogenesis. Authors present here a case report of a patient who presented with left sided severe chest pain investigated to have recurrent pleural effusion, and different clinico-radiological presentations. Computed Tomography (CT) scan showed a mediastinal mass from which CT guided biopsy was done and suggestive of Lymphoma. The patient responded to pleurodesis and chemotherapy.

Pulmonary Lymphangioleiomyomatosis and Role of Pleurodesis: Rare Case Reports

Pulmonary Lymphangioleiomyomatosis (LAM) is a rare disease, mostly seen in women of reproductive age group. Most common presentation is dyspnoea on exertion, may be associated with haemoptysis and chest pain. LAM is a cystic lung disease, with a poor prognosis and is difficult to treat. In this case reports, we discussed two patients who presented with dyspnoea and chest pain due to pneumothorax and were later diagnosed as case of LAM on clinical and radiological basis. Intercostal Chest tube Drainage (ICD) was inserted for resolution of pneumothorax and subsequently pleurodesis was done to prevent recurrent pneumothorax. In case of recurrent pneumothorax, LAM should be considered as a differential diagnosis. Pleurodesis can be considered to prevent recurrent pneumothorax.

Tubercular Mediastinal Abscess in Non-immunocompromised Patient: A Rare Case Presentation

Mediastinal tuberculosis is a rare infection resulting from direct inoculation of organisms or through hematogenous spread. Infected lymph nodes may also transfer the bacilli through lymphatic route. Mediastinal tuberculosis may resemble a pyogenic abscess or tumour which might indicate tubercular aetiology and remains a clinical challenge. In tuberculosis endemic countries like India, all the abscesses indolent to routine treatment need investigation to rule out mycobacterial causes. Authors hereby report a case of 60-year-old male with anterior mediastinal tubercular abscess.

Mounier-Kuhn Syndrome- A Rare Case Report

Mounier-Kuhn syndrome (M-K Syndrome) also known as Tracheobronchomalacia (TBM) often seen in middle aged and elderly people. Weakness of the tracheal and bronchial walls allows the posterior and anterior walls to draw nearer together during expiration and coughing, producing a varying obstruction. The main complaints are dyspnea, cough, phlegm and haemoptysis. Acquired TBM often presents with recurrent respiratory tract infections and mistreated as chronic bronchitis, pneumonia and the dyspnea, often treated as asthma, with poorer outcomes. Here, a case of 70-year-old male was presented with complaints of cough with expectoration since four months. Bronchoscopy, cineradiography, spirometry and intrabronchial pressure measurements are the diagnostic methods used. TBM is a progressive condition and to be considered in the diagnosis of obstructive pulmonary diseases and in the assessment of the functioning capacity of dyspneic patients. Treatment is conservative and symptomatic; in selected cases surgery may also be beneficial.

Pulmonary Nocardiosis in Immunocompetent Patient: A Rare Case Report

Pulmonary nocardiosis is a rare bacterial infection that may lead to severe disease in immunodeficient patients and usually not so common in immunocompetent patients. The report is about a 57-year-old male with Norcardiosis. His sputum and Bronchial Alveolar Lavage (BAL) were negative for acid-fast bacilli. Nocardia species was isolated in BAL culture. He was started on Trimethoprim/Sulfamethoxazole and Clarithromycin, which was later continued for six months.