Diversity of wheat anti-microbial peptides

From seeds of Triticum kiharae Dorof. et Migusch., 24 novel anti-microbial peptides were isolated and characterized by a combination of three-step HPLC (affinity, size-exclusion and reversed-phase) with matrix-assisted laser-desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry and Edman degradation. Based on sequence similarity and cysteine motifs, partially sequenced peptides were assigned to 7 families: defensins, thionins, lipid-transfer proteins, hevein-like peptides, knottin-like peptides, glycine-rich peptides, and MBP-1 homologs. A novel subfamily of defensins consisting of 6 peptides and a new family of glycine-rich (8 peptides with different repeat motifs) were identified. Three 6-cysteine knottin-like peptides represented by N- and C-terminally truncated variants revealed no sequence homology to any known plant anti-microbial peptides. A new 8-cysteine hevein-like peptide and three 4-cysteine peptides homologous to MBP-1 from maize were isolated. This is the first communication on the occurrence of nearly all families of plant anti-microbial peptides in a single species.     

Microsecond Time-Resolved Absorption Spectroscopy Used to Study CO Compounds of Cytochrome bd from Escherichia coli

Cytochrome bd is a tri-heme (b ₅₅₈, b ₅₉₅, d) respiratory oxygen reductase that is found in many bacteria including pathogenic species. It couples the electron transfer from quinol to O₂ with generation of an electrochemical proton gradient. We examined photolysis and subsequent recombination of CO with isolated cytochrome bd from Escherichia coli in one-electron reduced (MV) and fully reduced (R) states by microsecond time-resolved absorption spectroscopy at 532-nm excitation. Both Soret and visible band regions were examined. CO photodissociation from MV enzyme possibly causes fast (τ<1.5 µs) electron transfer from heme d to heme b ₅₉₅ in a small fraction of the protein, not reported earlier. Then the electron migrates to heme b ₅₅₈ (τ∼16 µs). It returns from the b-hemes to heme d with τ∼180 µs. Unlike cytochrome bd in the R state, in MV enzyme the apparent contribution of absorbance changes associated with CO dissociation from heme d is small, if any. Photodissociation of CO from heme d in MV enzyme is suggested to be accompanied by the binding of an internal ligand (L) at the opposite side of the heme. CO recombines with heme d (τ∼16 µs) yielding a transient hexacoordinate state (CO-Fe²⁺-L). Then the ligand slowly (τ∼30 ms) dissociates from heme d. Recombination of CO with a reduced heme b in a fraction of the MV sample may also contribute to the 30-ms phase. In R enzyme, CO recombines to heme d (τ∼20 µs), some heme b ₅₅₈ (τ∼0.2–3 ms), and finally migrates from heme d to heme b ₅₉₅ (τ∼24 ms) in ∼5% of the enzyme population. Data are consistent with the recent nanosecond study of Rappaport et al. conducted on the membranes at 640-nm excitation but limited to the Soret band. The additional phases were revealed due to differences in excitation and other experimental conditions.     

Computational modeling of drug transport and mixing in the chemofilter device: enhancing the removal of chemotherapeutics from circulation

Biomechanics and Modeling in Mechanobiology - Intra-arterial chemotherapy (IAC) is the preferred treatment for non-resectable hepatocellular carcinoma. A large fraction of IAC drugs, e.g.,...     

Cardioprotective effects of verapamil on myocardial structure and function in a murine model of chronic Trypanosoma cruzi infection (Brazil Strain): an echocardiographic study.

Verapamil has been shown to attenuate the extent of myocardial injury in murine models of chronic Trypanosoma cruzi infection. Infected mice treated with verapamil have significantly lower myocardial expression of inducible nitric oxide synthase and cytokines and substantially less inflammatory infiltrate and myocyte necrosis at necropsy. In the present study, we examined the cardiac structural and functional correlates of verapamil treatment in CD1 mice infected with the Brazil strain of T. cruzi using serial transthoracic echocardiography. There were four groups: uninfected- untreated control, uninfected-verapamil-treated, infected-untreated control, and infected-verapamil-treated. Verapamil was given in drinking water (1 gm/l) continuously from the day of infection for a total of 120 days. Mice were evaluated at baseline, 40 and 150 days p.i. Mice in the untreated-infected group compared with the mice in the infected-verapamil-treated group showed thinning of the left ventricular wall (0.84 +/- 0.02-vs-0.92 +/- 0.04, P<0.05 mm), increase in the left ventricular end-diastolic diameter (3.27 +/- 0.15-vs-2.74 +/- 0.05 mm, P<0.05) and reduction in percent fractional shortening (37 +/- 2-vs-53 +/- 4%, P<0.05). No differences in these parameters were noted among mice in the uninfected-untreated and uninfected-verapamil-treated groups. Furthermore, right ventricular dilation was more severe in mice from the infected-untreated group as compared with those in the infected- verapamil-treated group (visual grade 1.9 +/- 0.4-vs-1.0 +/- 0.2, P<0.05). At necropsy, the extent of myocardial injury, as determined histologically, was significantly greater in the infected-untreated mice. These data provide cardiac structural and functional correlates for the previously observed cardioprotective effects of verapamil in chronic chagasic cardiomyopathy.     

Temperature and state dependence of dynamic phrenic oscillations in the decerebrate juvenile rat

The aim of the present study was to determine characteristics of fast oscillations in the juvenile rat phrenic nerve (Ph) and to establish their temperature and state dependence. Two different age-matched decerebrate, baro- and chemodenervated rat preparations, in vivo and in situ arterially perfused models, were used to examine three systemic properties: 1) generation and dynamics of fast oscillations in Ph activity (both preparations), 2) responses to anoxia (both preparations), and 3) the effects of temperature on fast oscillations (in situ only). Both juvenile preparations generated power and coherence in two major bands analogous to adult medium- and high-frequency oscillations (HFO) at frequencies that increased with temperature but were lower than in adults. At < 28 degrees C, however, Ph oscillations were confined primarily to one low-frequency band (20-45 Hz). During sustained anoxia, both preparations produced stereotypical state changes from eupnea to hyperpnea to transition bursting (a behavior present only in vivo during incomplete ischemia) to gasping. Thus the juvenile rat produces a sequential pattern of responses to anoxia that are intermediate forms between those produced by neonates and those produced by adults. Time-frequency analysis determined that fast oscillations demonstrated dynamics over the course of the inspiratory burst and a state dependence similar to that of adults in vivo in which hyperpnea (and transition) bursts are associated with increases in HFO, while gasping contains no HFO. Our results confirm that both the fast oscillations in Ph activity and the coherence between Ph pairs produced by the juvenile rat are profoundly state- and temperature-dependent.     

A Model of Hydrodynamic Interaction Between Swimming Bacteria

We study the dynamics and interaction of two swimming bacteria, modeled by self-propelled dumbbell-type structures. We focus on alignment dynamics of a coplanar pair of elongated swimmers, which propel themselves either by “pushing” or “pulling” both in three- and quasi-two-dimensional geometries of space. We derive asymptotic expressions for the dynamics of the pair, which complemented by numerical experiments, indicate that the tendency of bacteria to swim in or swim off depends strongly on the position of the propulsion force. In particular, we observe that positioning of the effective propulsion force inside the dumbbell results in qualitative agreement with the dynamics observed in experiments, such as mutual alignment of converging bacteria.     

Time-frequency coherence analysis of phrenic and hypoglossal activity in the decerebrate rat during eupnea, hyperpnea, and gasping

Fast respiratory rhythms include medium- (MFO) and high-frequency oscillations (HFO), which are much faster than the fundamental breathing rhythm. According to previous studies, HFO is characterized by high coherence (Coh) in phrenic (Ph) nerve activity, thereby providing a means of distinguishing between these two types of oscillations. Changes in Coh between the Ph and hypoglossal (XII) nerves during the transition from normal eupnic breathing to gasping have not been characterized. Experiments were performed on nine unanesthetized, chemo- and barodenervated, decerebrate adult rats, in which sustained asphyxia elicited hyperpnea and gasping. A gated time-frequency Coh analysis was developed and applied to whole Ph and medial XII nerve recordings. The results showed dynamic Ph-Ph Coh during eupnea, including MFO and HFO. XII-XII Coh during eupnea was broadband and included four distinct peaks, with low-frequency Coh dominating the epochs preceding the onset of Ph activity. During gasping, only MFO-peaks were present in Ph-Ph Coh. Bilateral XII activity showed a significant reduction in Coh and a shift toward lower frequencies during gasping. In contrast, contralateral Ph-XII Coh progressively increased during state changes from eupnea to gasping, a tendency mirrored in the startup part of the Ph activity. These data suggest significant hypoxia/hypercapnia-induced alterations in synchronization between respiratory outputs during the transition from eupnea to gasping, reflecting a reconfiguration of the respiratory network and/or alterations in the circuitry associated with the motor pools, including dynamic coupling between outputs.     

Effect of N-terminal and Met23 mutations on the structure and dynamics of onconase

Onconase (rONC), otherwise known as ranpirnase or P-30 protein, which was initially purified from extracts of Rana pipiens oocytes and early embryos, exhibits anticancer activity both in vitro and in vivo and is in phase III clinical trials for tumor therapy. We have determined the solution NMR structure of a recombinant onconase with Met(-1), Gln1, and Leu23 residues (M-1, Q1, M23L)rONC. The 20 best solution structures had a backbone root mean square deviation of 0.41 +/- 0.09 A with respect to the average structure. The energy-minimized average NMR structure had a backbone root mean square deviation of 0.72 A from the x-ray crystallographic structure of native onconase; however, the orientation of the N-terminal residue in the two structures was very different. Comparison of the 15N HSQC spectrum of (M-1, Q1, M23L)rONC with that of a mutant E1S-rONC, which is identical to the nONC except with the N-terminal pyroglutamyl residue replaced by Ser, showed that N-terminal and residue 23 mutations induced structural changes in regions beyond the mutation sites. Model-free analysis of the backbone amide 15N-T1, 15N-T2, and 15N-1H NOE relaxation data for (M-1, Q1, M23L)rONC and E1S-rONC revealed that the E1S-rONC molecule showed very little flexibility, whereas (M-1, Q1, M23L)rONC exhibited substantial flexibility, which may account for the previously observed reduced stability and increased protease susceptibility. The alpha1 helix and beta-sheets of (M-1, Q1, M23L)rONC displayed bending motions. These data provided strong evidence for the presence of an N-terminal hydrogen bond network in E1S-rONC, but not in (M-1, Q1, M23L)rONC.     

Mechanisms of amino acid polycondensation on silica and alumina surfaces

Chemisorption products of bifunctional amino acid vapours on the surface of silica and alumina have been studied by the method of infrared spectroscopy. On the basis of the analysis of spectral data it is supposed that heterogeneous polycondensation of amino acids with formation of peptides proceeds under these conditions. The supposition was confirmed by the study of products of interaction of amino acid vapours with silica and alumina by the method of fast atom bombardment mass-spectrometry. It is established that in contrast to alumina the condensation of amino acids into linear peptides on silica surface proceeds only at presence of at least small amounts of water. The most probable mechanisms of extending of peptide chains are proposed on the basis of obtained experimental data.     

Risk Factors Associated with Default from Multi- and Extensively Drug-Resistant Tuberculosis Treatment,Uzbekistan: A Retrospective Cohort Analysis

Background

The Médecins Sans Frontières project of Uzbekistan has provided multidrug-resistant tuberculosis treatment in the Karakalpakstan region since 2003. Rates of default from treatment have been high, despite psychosocial support, increasing particularly since programme scale-up in 2007. We aimed to determine factors associated with default in multi- and extensively drug-resistant tuberculosis patients who started treatment between 2003 and 2008 and thus had finished approximately 2 years of treatment by the end of 2010.

Methods

A retrospective cohort analysis of multi- and extensively drug-resistant tuberculosis patients enrolled in treatment between 2003 and 2008 compared baseline demographic characteristics and possible risk factors for default. Default was defined as missing ≥60 consecutive days of treatment (all drugs). Data were routinely collected during treatment and entered in a database. Potential risk factors for default were assessed in univariate analysis using chi-square test and in multivariate analysis with logistic regression.

Results

20% (142/710) of patients defaulted after a median of 6 months treatment (IQR 2.6–9.9). Factors associated with default included severity of resistance patterns (pre-extensively drug-resistant/extensively drug-resistant tuberculosis adjusted odds ratio 0.52, 95%CI: 0.31–0.86), previous default (2.38, 1.09–5.24) and age >45 years (1.77, 1.10–2.87). The default rate was 14% (42/294) for patients enrolled 2003–2006 and 24% (100/416) for 2007–2008 enrolments (p = 0.001).

Conclusions

Default from treatment was high and increased with programme scale-up. It is essential to ensure scale-up of treatment is accompanied with scale-up of staff and patient support. A successful first course of tuberculosis treatment is important; patients who had previously defaulted were at increased risk of default and death. The protective effect of severe resistance profiles suggests that understanding disease severity or fear may motivate against default. Targeted health education and support for at-risk patients after 5 months of treatment when many begin to feel better may decrease default.