The DnaA AAA+ Domain His136 Residue Directs DnaB Replicative Helicase to the Unwound Region of the Replication Origin, oriC

Chromosomal replication initiation requires dynamic mechanisms in higher-order nucleoprotein complexes that are constructed at the origin of replication. In Escherichia coli, DnaA molecules construct functional oligomers at the origin oriC, enabling localized unwinding of oriC and stable binding of DnaB helicases via multiple domain I molecules of oriC-bound DnaA. DnaA-bound DnaB helicases are then loaded onto the unwound region of oriC for construction of a pair of replisomes for bidirectional replication. However, mechanisms of DnaB loading to the unwound oriC remain largely elusive. In this study, we determined that His136 of DnaA domain III has an important role in loading of DnaB helicases onto the unwound oriC. DnaA H136A mutant protein was impaired in replication initiation in vivo, and in DnaB loading to the unwound oriC in vitro, whereas the protein fully sustained activities for oriC unwinding and DnaA domain I-dependent stable binding between DnaA and DnaB. Functional and structural analyses supported the idea that transient weak interactions between DnaB helicase and DnaA His136 within specific protomers of DnaA oligomers direct DnaB to a region in close proximity to single stranded DNA at unwound oriC bound to DnaA domain III of the DnaA oligomer. The aromatic moiety of His136 is basically conserved at corresponding residues of eubacterial DnaA orthologs, implying that the guidance function of DnaB is common to all eubacterial species

Discovery of an orally active benzoxaborole prodrug effective in the treatment of Chagas disease in non-human primates

Trypanosoma cruzi, the agent of Chagas disease, probably infects tens of millions of people, primarily in Latin America, causing morbidity and mortality. The options for treatment and prevention of Chagas disease are limited and underutilized. Here we describe the discovery of a series of benzoxaborole compounds with nanomolar activity against extra- and intracellular stages of T. cruzi. Leveraging both ongoing drug discovery efforts in related kinetoplastids, and the exceptional models for rapid drug screening and optimization in T. cruzi, we have identified the prodrug AN15368 that is activated by parasite carboxypeptidases to yield a compound that targets the messenger RNA processing pathway in T. cruzi. AN15368 was found to be active in vitro and in vivo against a range of genetically distinct T. cruzi lineages and was uniformly curative in non-human primates (NHPs) with long-term naturally acquired infections. Treatment in NHPs also revealed no detectable acute toxicity or long-term health or reproductive impact. Thus, AN15368 is an extensively validated and apparently safe, clinically ready candidate with promising potential for prevention and treatment of Chagas disease

Clinical Analysis of Perforated Intestinal Behcet Disease

Clinical pattern of perforated intestinal Behcet disease was analyzed in the five patients who underwent surgery in terms of preoperative symptoms, the condition of perforation, the extent of resection and recurrence. In the experienced patients, recurrences were included in four of the five patients in spite of treatment. Perforation was based on deep multiple ulcers, characteristic of the punchedout type. It is emphasized that intestinal Behcet disease is more likely to occur as a catastrophic event of perforation which requires an urgent operation, and more extensive resection is mandatory for prevention of recurrence

Esophageal Carcinomas with Synchronous and Metachronous Primary Malignant Carcinomas in Other Organs

Seventeen patients with 10 synchronous and 7 metachronous double cancers with carcinomas of the esophagus were surgically treated in the First Department of Surgery, Nagasaki University School of Medicine. All patients were men with an average of age 68.5. The incidence of double cancers with carcinoma of the esophagus accounted for 12.7% in a total of 134 of this series. The three triple cancers were included. Of the three, one was synchronous triple cancers in the esophagus, the stomach and the colon. The outcome was not necessarily satisfactory. Two had recurrence 3 and 5 months after surgery, but one is still alive for 33 months, free from carcinoma

Significance of Needle Aspiration Biopsy for Breast Cancer

The results of aspiration biopsy cytology were clinically evaluated on the basis of clinical experience with 608 patients with breast cancer at the First Department of Surgery, Nagasaki University School of Medicine. Aspiration biopsy is of clinical value in making a diagnosis of small-sized tumors. There was no detrimental outcome to promote tumor-cell spread locally as well as to give rise to distant metastasis into the other organ. One should be aware of a no cell finding in relation to scirrhous carcinoma and intraductal papillomatosis. Emphasis is placed on recommendation of open biopsy without repeated aspiration maneuver

SCYX-7158, an Orally-Active Benzoxaborole for the Treatment of Stage 2 Human African Trypanosomiasis

Human African trypanosomiasis (HAT) is caused by infection with the parasite Trypanosoma brucei and is an important public health problem in sub-Saharan Africa. New, safe, and effective drugs are urgently needed to treat HAT, particularly stage 2 disease where the parasite infects the brain. Existing therapies for HAT have poor safety profiles, difficult treatment regimens, limited effectiveness, and a high cost of goods. Through an integrated drug discovery project, we have discovered and optimized a novel class of boron-containing small molecules, benzoxaboroles, to deliver SCYX-7158, an orally active preclinical drug candidate. SCYX-7158 cured mice infected with T. brucei, both in the blood and in the brain. Extensive pharmacokinetic characterization of SCYX-7158 in rodents and non-human primates supports the potential of this drug candidate for progression to IND-enabling studies in advance of clinical trials for stage 2 HAT