Harmonic analysis of perfusion pumps

The controversy over the use of nonpulsatile versus pulsatile pumps for maintenance of normal organ function during ex vivo perfusion has continued for many years, but resolution has been limited by lack of a congruent mathematical definition of pulsatility. We hypothesized that the waveform frequency and amplitude, as well as the underlying mean distending pressure are all key parameters controlling vascular function. Using discrete Fourier Analysis, our data demonstrate the complexity of the pulmonary arterial pressure waveform in vivo and the failure of commonly available perfusion pumps to mimic in vivo dynamics. In addition, our data show that the key harmonic signatures are intrinsic to the perfusion pumps, are similar for flow and pressure waveforms, and are unchanged by characteristics of the downstream perfusion circuit or perfusate viscosity.     

Genetic variation in Pueraria lobata (Fabaceae), an introduced, clonal, invasive plant of the southeastern United States

Pueraria lobata (kudzu), a clonal, leguminous vine, is invading the southeastern United States at a rate of 50 000 ha per year. Genetic variability and clonal diversity were measured in 20 southeastern U.S. populations using 14 allozyme loci. Within its U.S. range, 92.9% of the loci were polymorphic and overall genetic diversity was 0.290. Such high levels of genetic diversity are consistent with its history of multiple introductions over an extended period of time. The average proportions of polymorphic loci and genetic diversity within populations were 55.7% (range = 28.6–85.7%) and 0.213 (range = 0.114–0.317), respectively. The proportion of total genetic diversity found among populations was similar to species with equivalent life history characters (G_ST = 0.199). No regional patterns of variation were seen. The number of putative genotypes in each population ranged from 2 to 26. Mean genotypic diversity was 0.694, ranging from 0.223 to 0.955. Such high levels of genotypic diversity indicate that local sites are often colonized by several propagules (most likely seeds) and/or that sexual reproduction occurs within populations after establishment. An excess of heterozygosity was observed in populations with few unique genets, implying that selection for highly heterozygous individuals may occur in populations of P. lobata.     

Dimethylsulfone as a growth substrate for novel methylotrophic species of Hyphomicrobium and Arthrobacter

Dimethylsulfone is a major product of the chemical oxidation in the atmosphere of the principal biogenic sulfur gas, dimethylsulfide, but no studies have been reported on the mechanisms for its microbiological degradation. Three novel strains of bacteria have been isolated from enrichment cultures provided with dimethylsulfone as the only carbon and energy substrate. These are novel facultatively methylotrophic species of Hyphonmicrobium and Arthobacter, capable of growth on a range of one-carbon substrates. Cell-free extracts contained activities of enzymes necessary for a reductive/oxidative pathway for dimethylsulfone degradation: membrane-bound-dimethylsulfone and dimethylsulfoxide reductases, dimethylsulfide monooxygenase, and methanethiol oxidase. Enzymatic evidence is also presented for the subsequent oxidation of formaldehyde by formaldehyde and formate dehydrogenases in the Hyphomicrobium strain and by a dissimilatory ribulose monophosphate cycle in the Arthrobacter strains. The strains also grew on dimethylsulfoxide and dimethylsulfide, and dimethylsulfide-grown bacteria oxidized dimethylsulfide and dimethylsulfoxide but not dimethylsulfone. Formaldehyde assimilation was effected in the Hyphomicrobium strain by the serine pathway, but enzymes of the ribulose monophosphate cycle for formaldehyde assimilation were present in the Arthrobacter strains grown on dimethylsulfone. In contrast, one of the Arthrobacter strains was shown to switch to the serine pathway during growth on methanol. Growth yields on dimethylsulfone and formaldehyde were consistent with the occurrence of the serine pathway in Hyphomicrobium strain S1 and the ribulose monophosphate cycle in Arthrobacter strain TGA, and with the proposed reductive pathway for dimethylsulfone degradation in both.     

Synthesis of allysine ethylene acetal using phenylalanine dehydrogenase from Thermoactinomyces intermedius

Allysine ethylene acetal [(S)-2-amino-5-(1,3-dioxolan-2-yl)-pentanoic acid (2)] was prepared from the corresponding keto acid by reductive amination using phenylalanine dehydrogenase (PDH) from Thermoactinomyces intermedius ATCC 33205. Glutamate, alanine, and leucine dehydrogenases, and PDH from Sporosarcina species (listed in order of increasing effectiveness) also gave the desired amino acid but were less effective. The reaction requires ammonia and NADH. NAD produced during the reaction was recyled to NADH by the oxidation of formate to CO(2) using formate dehydrogenase (FDH). PDH was produced by growth of T. intermedius ATCC 33205 or by growth of recombinant Escherichia coli or Pichia pastoris expressing the Thermoactinomyces enzyme. Using heat-dried T. intermedius as a source of PDH and heat-dried Candida boidinii SC13822 as a source of FDH,98%, but production of T. intermedius could not be scaled up. Using heat-dried recombinant E. coli as a source of PDH and heat-dried Candida boidinii 98%. In a third generation process, heat-dried methanol-grown P. pastoris expressing endogenous FDH and recombinant Thermoactinomyces98% ee.     

What are we missing with only ground‐level mist nets? Using elevated nets at a migration stopover site

ABSTRACT Mist nets deployed in a standard ground‐level fashion capture birds approximately 0.5–2.6 m above the ground. In habitats where the vegetation extends above this height, standard mist net deployment may inadequately sample the targeted avian community and age‐ and sex‐classes within species. Such sampling biases may raise questions regarding studies based on data from mist‐net captures. To determine if birds were equally likely to be captured by mist nets at different heights, we constructed a series of paired ground‐level and elevated mist nets (hereafter “net rigs”) at a research station in western New York State. Net rigs were operated during 14 migration seasons from 2000 to 2006 (spring and fall each year), and 19,735 birds of 118 species were captured. Capture rates were significantly higher in ground‐level nets, but 12 species were only captured in elevated nets. Of 44 species with at least 50 captures, 25 species were more likely to be captured in the ground‐level nets and two species in the elevated nets. For four of 18 species, more birds were captured in the elevated nets during fall migration than during spring migration. We conclude that standard ground‐level net placement was more efficient in capturing birds in the secondary growth habitats that we sampled. However, ground‐level nets may not adequately sample the entire targeted community or all age‐ or sex‐classes within species.     

The Vaginal Microbiota over an 8- to 10-Year Period in a Cohort of HIV-Infected and HIV-Uninfected Women

BackgroundWe identified predominant vaginal microbiota communities, changes over time, and how this varied by HIV status and other factors in a cohort of 64 women.MethodsBacterial DNA was extracted from reposited cervicovaginal lavage samples collected annually over an 8–10 year period from Chicago Women’s Interagency HIV Study participants: 22 HIV-negative, 22 HIV-positive with stable infection, 20 HIV-positive with progressive infection. The vaginal microbiota was defined by pyrosequencing of the V1/V2 region of the 16S rRNA gene. Scheduled visits included Bacterial vaginsosis (BV) screening; clinically detected cases were referred for treatment. Hierarchical clustering identified bacterial community state types (CST). Multinomial mixed effects modeling determined trends over time in CST, by HIV status and other factors.ResultsThe median follow-up time was 8.1 years (range 5.5–15.3). Six CSTs were identified. The mean relative abundance (RA) of Lactobacillus spp. by CST (with median number of bacterial taxa) was: CST-1–25.7% (10), CST-2–27.1% (11), CST-3–34.6% (9), CST-4–46.8% (9), CST-5–57.9% (4), CST-6–69.4% (2). The two CSTs representing the highest RA of Lactobacillus and lowest diversity increased with each additional year of follow-up (CST-5, adjusted odds ratio (aOR) = 1.62 [95% CI: 1.34–1.94]; CST-6, aOR = 1.57 [95 CI: 1.31–1.89]), while the two CSTs representing lowest RA of Lactobacillus and higher diversity decreased with each additional year (CST-1, aOR = 0.89 [95% CI: 0.80–1.00]; CST-2, aOR = 0.86 [95% CI: 0.75–0.99]). There was no association between HIV status and CST at baseline or over time. CSTs representing lower RA of Lactobacillus were associated with current cigarette smoking.ConclusionsThe vaginal microbial community significantly improved over time in this cohort of women with HIV and at high risk for HIV who had regular detection and treatment referral for BV.