Even when DNA sequencing of purified DNA template failed under the optimal condition, it can be generally contributed to high GC content. GC-rich region of template causes a secondary structure to produce shorter readable sequence. To solve this problem, the sequencing reaction was modified by using dimethyl sulfoxide (DMSO). It was found that 5% (v/v) of DMSO in the reaction mixture recovers sequencing signal intensity with reduced frequency of ambiguous bases. When DMSO was added to sequencing reaction of DNA template with normal GC content, it did not show any adverse effect. Sequencing accuracy and unambiguous base frequency were significantly improved at concentration of 2% to 5% (v/v) DMSO in GC-rich DNA template. DMSO has been empirically introduced to enhance the efficiency of PCR in GC-rich templates. However, the underlying mechanism of improved cycle sequencing by DMSO is unknown. Thus, cycle sequencing reaction was remodified with other additives such as N-methyl imidazole, N-methyl2-pyrrolidone, N-methyl-2-pyridone and glycerol, possessing the similar chemical properties as DMSO. Most of methyl nitrogen ring-containing chemicals did not improve sequencing accuracy, whereas only glycerol mimicked the positive effect of DMSO by the same extent. In the present study, we suggest that the treatment of DMSO improve cycle sequencing by the alteration of structural conformation of GC-rich DNA template.
Base Composition ; DNA/chemistry* ; Dimethyl Sulfoxide/pharmacology* ; Plasmids/genetics ; Polymerase Chain Reaction/methods* ; Sequence Analysis, DNA* ; Solvents/pharmacology ; Solvents/chemistry ; Templates

Panniculitis generally indicates a group of diseases whose hallmark is fibrous thickening and chronic inflammation of subcutaneous fat. Various factors seem to induce a similar pathological histology, and morphological differences can be found among the patients diagnosed with the same disease. Paraneoplastic causes account for 3~10% of the cases of panniculitis. The commonest causes of cancer associated panniculitis are hematological malignancies and mostly lymphomas. In this case, we confirmed acute myeloid leukemia by a blood test and bone marrow examination, and with considering the clinical aspects and pathological findings of the skin lesion, and we finally diagnosed the patient as having panniculitis, which seems to be related with acute myeloid leukemia. The obvious clinical symptoms or pathophysiological features of this rare type of panniculitis are not yet fully known, and so making the differential diagnosis is needed to distinguish this malady from erythema nodosum, erythema induratum and various connective tissue disorders with accompanying erythematous subcutaneous nodules. We diagnosed this very rare and interesting case of paraneoplastic panniculitis that seemed to be generated from acute myeloid leukemia. We report here on this case and we review the relevant literature.
Bone Marrow Examination ; Connective Tissue ; Diagnosis, Differential ; Erythema Induratum ; Erythema Nodosum ; Hematologic Neoplasms ; Hematologic Tests ; Humans ; Inflammation ; Leukemia, Myeloid, Acute ; Lymphoma ; Panniculitis ; Skin ; Subcutaneous Fat