Corynebacterium Pseudotuberculosis Infection in Goats V.

In 2 goat herds, one infected with Gorynebacterium pseudo-tuberculosis and one free from the infection,, goats were examined for superficial swellings on the shoulder and chest. All animals in this study had been vaccinated against paratuberculosis before the age of 4 weeks. The vaccine had been applied subcutaneously behind the shoulder. Twenty-two of 40 (55 %) and 31 of 45 (69 %) goats had such lesions in the infected and non-infected herds, respectively. The difference between the herds was not significant, P > 0.05. Swellings found behind the shoulder in 19 goat carcasses derived from 4 herds in which G. pseudotuberculosis infection occurred were examined bacteriologically. No bacteria could be isolated from such lesions in 15 animals, while G. pseudotuberculosis in pure culture was isolated from 3 carcasses, and a mixed bacterial flora from the re-maining carcass. Bacteria could not be isolated from lesions situated behind the shoulder in 7 carcasses from 3 herds free from G. pseudo-tuberculosis infection. It is concluded that most swellings on the shoulder and chest in goats were granulomas resulting from vaccination against paratuber-culosis.     

A new approach for estimating the crosslink density of covalently crosslinked ionic polysaccharide gels

For an ideal polysaccharide gel with a known total polymer chain contour length, crosslinks all of the same functionality and elastic chains all with the same contour length and stiffness, the gel crosslink density can readily be determined from measurements of the maximum volume of the swollen gel (Moe et al., (1991) Food Hydrocolloids, 5, (1/2), 119–123. In the case of randomly crosslinked polysaccharide gels, where the chain contour length between two adjacent crosslinks may vary greatly, it is often much more difficult to determine the crosslink density. This paper reports on an attempt to extend the use of maximum gel volume measurements to estimate crosslink density for the latter type of gel. This is done by calculating the maximum swelling volume for polymer networks with four-functional crosslinks, known elastic chain mean contour length and standard deviation. The numerical analysis involves the calculation of the equilibrium force at each crosslink as the network expands. This allows a detailed study of how the distribution of individual polymer chain contour lengths affects the maximum swelling volume. The computer simulation results are compared with the results from experimental measurements of the maximum volume of swollen covalently crosslinked sodium alginate gels.     

Heavy metal tolerance of marine phytoplankton. III. Combined effects of copper and zinc ions on cultures of four common species

The combined effects of copper and zinc ions on the growth of three marine diatoms and one dinoflagellate in culture have been studied. The two metals were found to act synergistically to all algae except Phaeodactylum tricornutum Bohlin. With this species an antagonistic effect was observed. Addition of zinc ions reduced the inhibition of growth caused by the more toxic copper ions. Zinc toxicity to this alga increased at low concentration of magnesium, indicating a common route for divalent metal ions in general.     

Salmonellae in avian wildlife in Norway from 1969 to 2000

Postmortem records of wild-living birds in Norway with laboratory-confirmed findings of salmonella infection were summarized for the period from 1969 to 2000. Salmonella spp. were isolated from 470 birds belonging to 26 species. The salmonella-positive birds included 441 small passerines, 15 gulls, 5 waterfowl, 4 birds of prey, 3 doves, and 2 crows. The bullfinch (Pyrrhula pyrrhula) was by far the most frequently recorded species (54% of the cases). Salmonella enterica serover Typhimurium was recovered from all cases except from one hooded crow (Corvus corone), which yielded serovar Paratyphi-B var. Java. Variant O:4,12 comprised 96% (451 cases) of all serovar Typhimurium isolates, including all the passerines, while variant O:4,5,12 accounted for the remaining 4% (18 cases). The occurrence of salmonellae in small passerines showed a distinct seasonality, with a peak in February and March. Plasmid profile analysis of 346 isolates of serovar Typhimurium O:4,12 detected six profiles, of which two comprised 66 and 28% of the isolates, respectively. Phage typing of 52 randomly selected isolates of serovar Typhimurium O:4,12 from passerines detected four types: DT 40 (54%), U277 (35%), DT 99 (6%), and DT 110 (4%).     

A high field NMR study of the products ensuing from konjak glucomannan C(6)-oxidation followed by enzymatic C(5)-epimerization

Konjak glucomannan (KGM) is a water-soluble linear copolymer of (1-->4) linked beta-D-mannopyranosyl and beta-D-glucopyranosyl units. It has been selectively C6-oxidized by a 2,2,6,6-tetramethylpiperidin-1-oxy mediated reaction to obtain the corresponding uronan. Oxidized KGM has been treated with three different C-5 epimerases, AlgE4, AlgE6, and AlgE1, to obtain uronans with a various content of alpha-L-gulopyranuronate residues, namely, KGME4, KGME6, and KGME1. By use of 1D selective and 2D NMR techniques, a full assignment of the high field (600 MHz) NMR spectra of the purified native KGM and of the oxidized and epimerized derivatives has been obtained. Since in the anomeric region of the (1)H NMR spectrum of native KGM, diads sensitivity is present, the glucose-glucose, glucose-mannose, mannose-mannose, and mannose-glucose distribution has been obtained. In the (13)C spectrum of oxidized KGM, due to the presence of triad sensitivity on the C-4 resonance of glucuronic and mannuronic units, a better sequential investigation has been possible. As a result the average length of mannuronic blocks, N(M) is obtained. When AlgE4, AlgE6, and AlgE1 enzymes are used for the epimerization of oxidized KGM, the reaction products differ significantly both in the proportion and in the distribution of the mannuronic and guluronic residues. In epimerized KGM derivatives, a careful deconvolution of (1)H spectra allows the measurement of the degree of epimerization. In the case of KGME1 and KGME6, the average blocks length, N(G), of the guluronic blocks introduced in the polysaccharidic chain with the epimerization has also been calculated. Due to the shortness of mannuronic blocks in the oxidized KGM before the epimerization, N(G) in the epimerized compounds is also very low.     

Galactose-substituted alginate: preliminary characterization and study of gelling properties

Coupling of alginate with 1-amino-1-deoxygalactose in the presence of 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide results in a substituted polymer containing galactose side linked via an amide bond. To clarify the degree and pattern of substitution, a (1)H NMR study on the anomeric region of modified alginate, polymannuronate, alginate enriched in guluronic acid (G-enriched alginate), and polyalternating MG, was carried out (G, alpha-l-guluronic acid; M, beta-d-mannuronic acid). From the resonance of the proton at position 1 of galactosylamine, it was possible to determine the amount of galactose linked to mannuronic and to guluronic residues, respectively. Furthermore, (1)H NMR spectroscopy revealed a higher reactivity of guluronic residues for low degrees of conversion. Modified alginates with 7% and 19% of substitution are both able to form stable beads in the presence of calcium ions. The effect of galactose substitution on the dimensions, swelling, and stability of the beads has been studied and the cytotoxicity of the modified polymer evaluated in preliminary biological tests.     

Grouping by plasmid profiles of atypical Aeromonas salmonicida isolated from fish, with special reference to salmonid fish

Plasmid profile analyses were performed for 113 strains of atypical Aeromonas salmonicida and the reference strain A. salmonicida subsp. salmonicida ATCC 14174. The atypical A. salmonicida strains comprised 98 strains obtained from fish originating from 54 farms and 2 lakes in Norway, 10 strains from Canada (2), Denmark (2), Finland (1), Iceland (1) and Sweden (4), the reference strains NCMB 1109 and ATCC 15711 (Haemophilus piscium) of A. salmonicida subsp. achromogenes, and the type cultures A. salmonicida subsp. achromogenes NCMB 1110, A. salmonicida subsp. masoucida ATCC 27013 and A. salmonicida subsp. smithia CCM 4103. A total of 95 strains of atypical A. salmonicida were separated into 7 groups (I to VII) based on the plasmid profiles. Eighteen strains of atypical A. salmonicida had no common plasmid profile. The type strain NCMB 1110 and the reference strain NCMB 1109 were included in group IV, and the type strain ATCC 27013 in group V, but the other reference and type strains had plasmid profiles different from all the other strains. An epidemiological link was documented between strains collected from different farms/localities in each of groups I, III, V and VII. Physiological and biochemical characterizations were performed for 93 of the strains to investigate phenotypic differences between the plasmid groups. Group VII strains and 3 strains with no common plasmid profile differed from the other groups in being catalase-negative. Differences in phenotypic characteristics were shown between the plasmid groups. However, significant variations in reactions for several phenotypic characteristics also occurred within each of the groups I to VII. The present study indicates that plasmid profiling may give useful epidemiological information during outbreaks of atypical A. salmonicida infections in fish. Additional comprehensive phenotypic characterisation is of limited value since the phenotypic characteristics in each plasmid group are not uniform.     

Doing No Harm? Adverse Events in a Nation-Wide Cohort of Patients with Multidrug-Resistant Tuberculosis in Nigeria

Background

Adverse events (AEs) of second line anti-tuberculosis drugs (SLDs) are relatively well documented. However, the actual burden has rarely been described in detail in programmatic settings. We investigated the occurrence of these events in the national cohort of multidrug-resistant tuberculosis (MDR-TB) patients in Nigeria.

Method

This was a retrospective, observational cohort study, using pharmacovigilance data systematically collected at all MDR-TB treatment centers in Nigeria. Characteristics of AEs during the intensive phase treatment were documented, and risk factors for development of AEs were assessed.

Results

Four hundred and sixty patients were included in the analysis: 62% were male; median age was 33 years [Interquartile Range (IQR):28–42] and median weight was 51 kg (IQR: 45–59). Two hundred and three (44%) patients experienced AEs; four died of conditions associated with SLD AEs. Gastro-intestinal (n = 100), neurological (n = 75), ototoxic (n = 72) and psychiatric (n = 60) AEs were the most commonly reported, whereas ototoxic and psychiatric AEs were the most debilitating. Majority of AEs developed after 1–2 months of therapy, and resolved in less than a month after treatment. Some treatment centers were twice as likely to report AEs compared with others, highlighting significant inconsistencies in reporting at different treatment centers. Patients with a higher body weight had an increased risk of experiencing AEs. No differences were observed in risk of AEs between HIV-infected and uninfected patients. Similarly, age was not significantly associated with AEs.

Conclusion

Patients in the Nigerian MDR-TB cohort experienced a wide range of AEs, some of which were disabling and fatal. Early identification and prompt management as well as standardized reporting of AEs at all levels of healthcare, including the community is urgently needed. Safer regimens for drug-resistant TB with the shortest duration are advocated.     

Tailor-made alginate bearing galactose moieties on mannuronic residues: selective modification achieved by a chemoenzymatic strategy

1-Amino-1-deoxygalactose (12%, mole) has been chemically introduced on a mannuronan sample via an N-glycosidic bond involving the uronic group of the mannuronic acid (M) residues. The unsubstituted M residues in the modified polymer were converted into guluronic moieties (G) by the use of two C-5 epimerases, resulting in an alginate-like molecule selectively modified on M residues. The molecular details of the newly formed polymer, in terms of both composition and molecular dimensions, were disclosed by use of (1)H NMR, intrinsic viscosity, and high-performance size-exclusion chromatography-multiple-angle laser light scattering (HPSEC-MALLS). Circular dichroism has revealed that the modified alginate-like polymer obtained after epimerization was able to bind calcium due to the introduction of alternating and homopolymeric G sequences. The gel-forming ability of this M-selectively modified material was tested and compared with an alginate sample containing 14% galactose introduced on G residues. Mechanical spectroscopy pointed out that the modified epimerized material was able to form stable gels and that the kinetics of the gel formation was similar to that of the unsubstituted sample. In contrast, the G-modified alginate samples showed a slower gel formation, eventually leading to gel characterized by a reduced storage modulus. The advantage of the selective modification on M residues was confirmed by measuring the Young's modulus of gel cylinders of the different samples. Furthermore, due to the high content in alternating sequences, a marked syneresis was disclosed for the modified-epimerized sample. Finally, calcium beads obtained from selectively M-modified alginate showed a higher stability than those from the G-modified alginate, as evaluated upon treatment with nongelling ions.