Mycobacteriophages are viruses that infect mycobacterial hosts. Expansion of a collection of sequenced phage genomes to a total of sixty -all infecting a common bacterial host -provides further insight into their diversity and evolution. Of the sixty phage genomes, 55 can be grouped into nine clusters according to their nucleotide sequence similarities, five of which can be further divided into subclusters; five genomes do not cluster with other phages. The sequence diversity between genomes within a cluster varies greatly; for example, the six genomes in cluster D share more than 97.5% average nucleotide similarity with each other. In contrast, similarity between the two genomes in Cluster I is barely detectable by diagonal plot analysis. The total of 6,858 predicted ORFs have been grouped into 1523 phamilies (phams) of related sequences, 46% of which possess only a single member. Only 18.8% of the phams have sequence similarity to non-mycobacteriophage database entries and fewer than 10% of all phams can be assigned functions based on database searching or synteny. Genome clustering facilitates the identification of genes that are in greatest genetic flux and are more likely to have been exchanged horizontally in relatively recent evolutionary time. Although mycobacteriophage genes exhibit smaller average size than genes of their host (205 residues compared to 315), phage genes in higher flux average only ∼100 amino acids, suggesting that the primary units of genetic exchange correspond to single protein domains.

The effects of 0.1% and 0.2% delmopinol mouthwashes on supragingival plaque flora were investigated in a 6-month home-use study. 141 subjects were studied from whom plaque was collected at baseline, 12, 24, and 36 weeks. Overall, there were no consistent effects on microscopic or total counts. However, there was a significant reduction in the proportion of dextran-producing streptococci in the active groups compared to the control group throughout treatment. There was no colonisation by Candida or Gram-negative aerobic bacilli in the active groups nor was there any decrease in susceptibility to delmopinol. Delmopinol appears to mediate its anti-plaque effect without causing a major shift in bacterial populations, although dextran-producing bacteria appear to be affected, which may have relevance to this agent's mode of action.

Background and Objectives Enumerating circulating tumor cells has been used as a method of monitoring progression of various cancers. Various methods for detecting circulating melanoma cells (CMCs) have been reported, but none has had sufficient sensitivity to determine if the presence of rare CMCs in the blood of Stage I–III melanoma patients predicts if those patients eventually develop metastatic disease. Study Design We quantified CMCs in serial blood samples from 38 early stage melanoma patients to determine if CMC numbers predict development of metastatic melanoma. CMCs were enumerated using a photoacoustic flow cytometric detection system that uses a laser to induce high frequency acoustic signals in pigmented CMCs. Results We observed that detection of greater than 2 CMCs/ml of blood from patients with Stage I–III melanoma predicts metastatic disease. Of the 11 patients we studied who had two or fewer CMCs detected at all time points tested, none progressed to metastatic disease over a mean follow‐up of 1288 days. In contrast, 18 of the 27 patients (67%) having more than 2 CMCs/ml at one or more time points progressed to metastatic disease over a mean follow‐up of 850 days. Conclusions Photoacoustic flow cytometry can detect rare CMCs in the blood of Stage I–III melanoma patients and detectionof these cells is predictive of subsequent development of metastatic disease. Lasers Surg. Med.

Bacteriophage L, a P22-like phage of Salmonella enterica sv Typhimurium LT2, was important for definition of mosaic organization of the lambdoid phage family and for characterization of restriction-modification systems of Salmonella. We report the complete genome sequences of bacteriophage L cI–40 13–am43 and L cII–101; the deduced sequence of wildtype L is 40,633 bp long with a 47.5% GC content. We compare this sequence with those of P22 and ST64T, and predict 72 Coding Sequences, 2 tRNA genes and 14 intergenic rho-independent transcription terminators. The overall genome organization of L agrees with earlier genetic and physical evidence; for example, no secondary immunity region (immI: ant, arc) or known genes for superinfection exclusion (sieA and sieB) are present. Proteomic analysis confirmed identification of virion proteins, along with low levels of assembly intermediates and host cell envelope proteins. The genome of L is 99.9% identical at the nucleotide level to that reported for phage ST64T, despite isolation on different continents ∼35 years apart. DNA modification by the epigenetic regulator Dam is generally incomplete. Dam modification is also selectively missing in one location, corresponding to the P22 phase-variation-sensitive promoter region of the serotype-converting gtrABC operon. The number of sites for SenLTIII (StySA) action may account for stronger restriction of L (13 sites) than of P22 (3 sites).