Kinetic Gas Hydrate Inhibition by Alternating Dipeptoids with Optimal Size and Shape N-Substituents.

Current commercial kinetic hydrate inhibitors (KHIs) are all based on water-soluble polymers with amphiphilic alkylamide or lactam groups. The size and shape of the hydrophobic moiety are known to be critical for optimum KHI performance. Proteins and peptides represent an environmentally friendly alternative, especially as bioengineering could be used to manufacture a product predetermined to have optimum KHI performance. Here, we explore a new series of polymers that are alternating dipeptoids where one of the peptide links originates from glycine. The dipeptoids contain n-propyl groups on the nitrogen atom and varying size and shape alkyl side chains on the neighboring carbon atom. Experiments were carried out in high-pressure steel rocking cells using the slow constant cooling (SCC) test method (1 °C/h) and a synthetic natural gas mixture. All the dipeptoids showed good KHI performance with the best result being for that with a glycine-N-propylleucine repeating unit (Poly iC4-Pr), which has pendant iso-butyl groups on the carbon atom. It exhibited the same KHI performance as poly(N-vinyl caprolactam). Dipeptoids with smaller or longer alkyl groups than iso-butyl gave worse performance. It is conjectured that the iso-butyl group is the optimal carbon length for this polymer class. In addition, the end-branching maximizes the van der Waals interaction with open cavities on growing hydrate particles, which must occur without loss of hydrogen-bonding from the neighboring peptide linkage for optimum KHI performance. Thus, the study provides further evidence for the premise that good KHI molecules must contain multiple amphiphilic groups (often as polymers) with optimal size and shape hydrophobic groups adjacent to strong hydrogen bonding groups. The solvent, n-butyl glycol ether, was shown to be a synergist for Poly iC4-Pr, lowering the onset temperature of hydrate formation in SSC tests relative to the polymer alone.

A Case of Eosinophilic Myocarditis Associated with Cardiogenic Shock.

The patient was a 32-year-old man with a previous history of bronchial asthma. He was admitted with chief complaints of dyspnea and skin rash associated with itching of the palms and soles of the feet, which began 2 weeks earlier. Because of the presence of cardiac failure and increase in the peripheral blood eosinophil count, eosinophilic myocarditis (EM) was suspected. His blood pressure gradually decreased and the patient went into cardiogenic shock. Therefore, endomyocardial biopsy was performed and was immediately followed by corticosteroid therapy and intra-aortic balloon pump (IABP) placement. With the findings of eosinophil infiltration associated with myocardial interstitial edema on endomyocardial biopsy, EM was diagnosed. In this case, early therapeutic intervention led to resolution of shock resolved and improvement of the peripheral blood eosinophilia and cardiac function; the patient was discharged 33 days after the onset of symptoms. EM is a rare cardiomyopathy in which myocardial eosinophil infiltration is seen. Although it has been perceived as having a mild clinical course, this report described a severe case of EM associated with cardiogenic shock, which improved as a result of early diagnosis and therapeutic intervention.

Primary Effusion Lymphoma-like Lymphoma in a Patient with Neurofibromatosis Type 1.

To date, there are only 15 case reports of lymphoma in patients with neurofibromatosis type 1 (NF1), a common autosomal dominant tumor predisposition syndrome. Here, we present the first report of a primary effusion lymphoma (PEL)-like lymphoma (PEL-L), which is a human herpes virus 8/Kaposi sarcoma herpes virus-unrelated PEL, in a 73-year-old woman with NF1. The woman presented with pleural effusion following surgery for a small intestinal gastrointestinal stromal tumor and a malignant peripheral nerve sheath tumor. We prepared cellblocks to accurately differentiate between PEL, PEL-L, and pyothorax-associated lymphoma, for establishing a starting point for treatment and for prolonging survival. Attention should be paid to malignant neoplasms in NF1 patients. Diffuse large B-cell lymphoma may not be a rare complication in these patients, although how NF1 promotes its development remains to be determined. PEL-L should be suspected when body cavity effusion is observed in elderly patients. If feasible, it should be treated via rituximab-containing chemotherapy, which according to the literature, results in longer survival times than does drainage or regimens consisting of cyclophosphamide, doxorubicin, vincristine, and prednisone.