De novo DNA synthesis using polymerase-nucleotide conjugates.

Oligonucleotides are almost exclusively synthesized using the nucleoside phosphoramidite method, even though it is limited to the direct synthesis of ∼200 mers and produces hazardous waste. Here, we describe an oligonucleotide synthesis strategy that uses the template-independent polymerase terminal deoxynucleotidyl transferase (TdT). Each TdT molecule is conjugated to a single deoxyribonucleoside triphosphate (dNTP) molecule that it can incorporate into a primer. After incorporation of the tethered dNTP, the 3' end of the primer remains covalently bound to TdT and is inaccessible to other TdT-dNTP molecules. Cleaving the linkage between TdT and the incorporated nucleotide releases the primer and allows subsequent extension. We demonstrate that TdT-dNTP conjugates can quantitatively extend a primer by a single nucleotide in 10-20 s, and that the scheme can be iterated to write a defined sequence. This approach may form the basis of an enzymatic oligonucleotide synthesizer.

Conidiobolomycosis in a young Malaysian woman showing chronic localized fibrosing leukocytoclastic vasculitis: a case report and meta-analysis focusing on clinicopathologic and therapeutic correlations with outcome.

BACKGROUND: Conidiobolomycosis (also known as rhinoentomophthoramycosis) is a rare cutaneous/mucosal fungal infection seen mainly in the tropical rain forest regions of the world that can be associated with disfiguring facial elephantiasis, and rarely, death. OBJECTIVE: To present an exemplary case report and perform a systematic review of the world's literature to more accurately describe the natural history and the effect of therapy on outcome in conidiobolomycosis. METHODS: Case report and meta-analysis of published case reports and series of conidiobolomycosis to determine which clinical, pathologic, mycologic, and treatment factors impact on prognosis. RESULTS: We document delay in diagnosis of conidiobolomycosis in a young Malaysian woman, whose biopsy showed pathognomonic features-massive tissue eosinophilia and Splendore-Hoeppli phenomenon surrounding broad hyphae. These findings coexisted with granuloma faciale-like changes (fibrosing leukocytoclastic vasculitis) and lymphedema. Treatment with multiple antifungals was followed by complete resolution. For the meta-analysis, pooled data from 199 cases (162 with full outcome data) from 120 reports revealed a similar course for most cases: a disease affecting healthy young adults who present with progressive nasal symptoms (eg, nasal obstruction) and central facial swelling and show improvement or cure after surgical excision and/or treatment with one or more antifungal agents in 83%. Persistent-progressive facial disease occurred in 11%, and 6% died rapidly of fungal infection. Presentation with facial elephantiasis correlated with persistent-progressive rhinoentomophthoramycosis and a longer duration of disease before diagnosis (P = 0.02). Lethal infections were significantly associated with nonstereotypical presentation (eg, orbital cellulitis), visceral infection, absence of the Splendore-Hoeppli phenomenon, presence of comorbidities (eg, immunosuppression, hematolymphoid malignancy), infection with Conidiobolus incongruus or Conidiobolus lamprauges (not Conidiobolus coronatus), lack of response to amphotericin B, and female sex (all P ≤ 0.002). The few sensitivity studies performed demonstrated in vitro multidrug resistance of Conidiobolus species to most available antifungal agents. LIMITATIONS: Publication bias, reporting heterogeneity, and data deficits may affect results. CONCLUSIONS: Conidiobolomycosis should be included in the differential diagnosis of patients who present with nasal symptoms and painless centrofacial swelling. Massive tissue eosinophilia and Splendore-Hoeppli material coating thin-walled hyphae confirms the clinical diagnosis. The granuloma faciale-like histology found in this case can explain the onset of facial lymphedema by fibroinflammatory destruction of lymphatic vessels; the duration of disease and severity of inflammation likely predicts whether the lymphedema is reversible or not. Although rhinoentomophthoramycosis ostensibly responds in vivo to most available antifungal agents, routine culture and susceptibility testing is recommended to better define the efficacy of these therapeutic agents.