Emergency weight estimation in Pacific Island and Maori children who are large-for-age

OBJECTIVE

Methods to estimate weights of children requiring resuscitation appeared to underestimate the weight of Pacific Island and Maori children. This study sought to quantify differences between real and estimated weights, study links with ethnicity and derive a new estimation method for large-for-age children.

METHOD

Data were collected prospectively for 3 months. Weights were estimated by formulae described by Shann, Leffler, the Advanced Paediatric Life Support (APLS) formula, the Oakley resuscitation chart and the Broselow tape.

RESULTS

Of the 909 children included, 46% were of Pacific Island and 25% were of Maori origin. Differences between actual and estimated weights were significantly greater (P<0.05) for the Pacific Island group using all methods of estimation. Maori differences were significantly greater than European differences using Oakley and Broselow methods (P<0.05). The Broselow tape was the method most likely to underestimate weight in Pacific Island and Maori children. A new formula was derived from non-linear regression analysis, leading to a new chart.

CONCLUSION

Current emergency methods underestimate weight in Pacific Island and Maori children. We recommend a new chart for these children.

Confirmation of Piscirickettsia salmonis as a pathogen in European sea bass Dicentrarchus labrax and phylogenetic comparison with salmonid strains

European sea bass Dicentrarchus labrax from the Mediterranean were diagnosed with a severe encephalitis. Rickettsia-like organisms (RLOs) were associated with brain lesions in routine paraffin sections. These were found to share common antigens with the Piscirickettsia salmonis type-strain, LF-89, by indirect fluorescent antibody test (IFAT) and by immunohistochemistry (IHC). In addition, we compared the DNA sequences of the 16S rDNA and 16S-23S internal transcribed spacer region (ITS) with those published for P. salmonis strains and found that the sea bass piscirickettsia-like organism (SBPLO) was another strain of P. salmonis, closely related to the salmonid pathogens. Furthermore, we showed that the SBPLO possessed at least 2 ITS regions, 1 of which contained tRNA genes.

Structure of the DNA octanucleotide d(ACGTACGT)2

d(ACGTACGT), C(78)H(84)N(30)O(32)P(7).20H(2)O, M(r) (DNA) = 2170, tetragonal, P4(3)2(1)2 (No 96), a = 42.845 (1), b = 42.845(1), c = 24.804 (1) A, V = 45532.5 (2) A(3), z = 8,lambda(MoKalpha) = 0.71069 A, micro (MoKalpha) = 0.10 mm(-1), T = 295 K, R = 0.18 for 1994 unique reflections between 5.0 and 1.9 A resolution. The self-complementary octanucleotide d(ACGTACGT)(2) has been crystallized and its structure determined to a resolution of 1.9 A. The asymmetric unit consists of a single strand of octamer with 20 water molecules. It is only the second example of an octanucleotide having terminal A.T base pairs whose structure has been determined by X-ray crystallography. The sequence adopts the modified A-type conformation found for all octanucleotide duplexes studied to date with the helix bent by approximately 15 degrees and an average tilt angle of 0 degrees. Unusually the data collection was carried out using a 3 kW molybdenum sealed-tube source. The conformational details are discussed in comparison with other closely related sequences.

Ultrastructural and molecular characterization of Bacillidium vesiculoformis n. sp. (Microspora: Mrazekiidae) in the freshwater oligochaete Nais simplex (Oligochaeta: Naididae)

The development of a new species, Bacillidium vesiculoformis n. sp. (Microspora, Mrazekiidae), is described from the freshwater oligochaete Nais simplex (Oligochaeta, Naididae). Initial stages of parasite development consist of a monokaryotic merogony within a haemocyte of the intestinal blood sinus. The resulting hypertrophied haemocyte is attached to the chloragocytes of the sinus by fine cytoplasmic extensions with the sinus around the cell becoming greatly enlarged. The meronts within the haemocyte form diplokaryotic sporonts that undergo sporogenesis directly within the cytoplasm of the host cell. The infected cell becomes packed with spores and developmental stages, causing it dramatically to increase in size, eventually rupturing the oligochaete and cell. Sporogony appears to be disporoblastic. Released spores were observed to have an adhesive quality. Transmission studies conducted with mature spores failed to transmit the parasite horizontally although vertical transmission was observed. Phylogenetic analysis of the parasite demonstrated that B. vesiculoformis clustered with microsporidian parasites of bryozoa and two other microsporidians, Janacekia debaiseuxi and an unidentified Bacillidium sp.

Structure of 9-amino-[N-(2-dimethylamino)propyl]acridine-4-carboxamide bound to d(CGTACG)(2): a comparison of structures of d(CGTACG)(2) complexed with intercalatorsin the presence of cobalt

The structure of the complex formed between 9-amino-[N-(2-dimethylamino)propyl]acridine-4-carboxamide and d(CGTACG)(2) has been refined to a resolution of 1.55 A. The complex crystallized in space group C222. An asymmetric unit comprises two strands of DNA, one disordered drug molecule, two cobalt(II) ions, two magnesium ions and 32 water molecules. The DNA helices stack in continuous columns, with their four central base pairs adopting a B-like motif. The terminal G.C base pairs engage in different interactions. At one end of the duplex there is a CpG dinucleotide overlap modified by ligand intercalation and terminal cytosine exchange between symmetry-related duplexes. An intercalation complex is formed involving four DNA duplexes, four disordered ligand molecules and two pairs of base tetrads. The other end of the DNA is frayed, with the terminal guanine lying in the minor groove of the next duplex in the column. The structure is stabilized by guanine N7-cobalt(II) coordination. The structure is compared with previously published isomorphous structures of d(CGTACG)(2) complexed with intercalators in the presence of cobalt and it is concluded that the formation of this crystal form is primarily determined by DNA-DNA interactions and packing forces, rather than by special interactions between the ligand and the DNA. Given the nature of the ligands found in these complexes, the relevance of the quadruplex structure to the biological activity of those agents, known to be topoisomerase poisons, is questioned.

Localization of carbohydrate terminals on Tetracapsuloides bryosalmonae using lectin histochemistry and immunogold electron microscopy

Tetracapsuloides bryosalmonae is the myxozoan parasite that causes the commercially important proliferative kidney disease (PKD) in salmonid aquaculture. Previous studies on the binding of lectins to T. bryosalmonae identified Griffonia simplificola agglutinin I (GS I) as useful for parasite identification. This lectin was also implicated as recognizing antigenic structures on the parasite. Here, we examine the histochemical staining and ultrastructural localization of a panel of 21 lectins on the extrasporogonic stage of T. bryosalmonae. The histochemical staining studies indicated that the majority of lectins bound to the renal stages of T. bryosalmonae, however not all of these lectins could be successfully localized using immunogold electron microscopy. Of the lectins that were localized many, including GS I, bound to membranes associated with the lysosomal pathway within the extrasporogonic primary cell of the parasite, indicating that these organelles are rich in glycoconjugates. The histochemical staining of Erythrina cristagalli ECL was unique and highlighted a different distribution of glycoconjugates in the periphery of some extrasporogonic parasites within the renal sinuses when compared with stages in the interstitium, suggesting the presence of distinct blood forms of T. bryosalmonae.

The effect of in vivo growth on the cellular and extracellular components of the marine bacterial pathogen Photobacterium damsela subsp. piscicida

Photobacterium damsela subsp. piscicida, the causative agent of fish pasteurellosis, was grown in vivo. Bacterial cells and extracellular products (ECPs) were analysed via electrophoresis and immunoblot analysis, using specific sea bass antisera. Growth in vivo induced the synthesis of unique bacterial cell proteins at > 206, 206, 21.3, 18, 7.6 and < 7.6 kDa. Sea bass serum raised against live bacterial cells of the pathogen and especially a sea bass serum raised against formalin-inactivated bacterial cells grown in a specific novel medium recognized the novel antigens at > 206 (associated with iron sequestration), 21.3, 7.6 and < 7.6 kDa, suggesting that the latter medium conserves the synthesis of natural bacterial cell proteins in vitro. In vivo growth of the pathogen induced the synthesis of more toxic ECPs in comparison with in vitro growth and an inverse correlation between total protein concentration in the ECPs and toxicity per unit of protein was observed. Substrate-polyacrylamide electrophoresis revealed the presence of in vivo synthesized ECPs of the pathogen (proteases) at 175, 132, < 79 and 48.3 kDa. Histological examination of tissues isolated from fish injected with these ECPs revealed inflammatory and necrotic lesions in the spleen, liver, head kidney, intestine and heart as soon as 48 h post-introduction of the ECPs.

Vaccination trials of sea bass, Dicentrarchus labrax (L.), against Photobacterium damsela subsp. piscicida, using novel vaccine mixtures

Bacterial cells of the marine fish pathogen Photobacterium damsela subsp. piscicida were grown in novel culture media. A mixture of whole cells and extracellular components was inactivated and used in bath, intraperitoneal (i.p.) and oral vaccination of sea bass, Dicentrarchus labrax, employing two sizes of fish. A commercial vaccine was used for comparative purposes. Control and immunized fish were either bath or intraperitoneally challenged 6 and 12 weeks post-vaccination. Small fish had significantly higher relative percentage survival with the novel vaccine mixture both at 6 and 12 weeks post-vaccination by bath, in comparison with the commercial vaccine. No protection was afforded at 6 or 12 weeks post-immunization by either vaccine after challenge via i.p. injection. Sea bass (1.5-2 g) intraperitoneally vaccinated with various adjuvanted vaccine mixtures were not protected against pasteurellosis. In contrast, larger sea bass (20 g) benefited from vaccination with the novel vaccine mixtures. Intraperitoneal challenge with the pathogen resulted in protection in both fish groups vaccinated with novel vaccine mixtures, whereas control fish suffered high mortalities (> 80%). Orally vaccinated fish were immersion challenged with the pathogen. At 6 and 12 weeks post-vaccination the control fish had a high mortality and the fish vaccinated with the novel vaccine mixture achieved good protection.

Comparison of chemical treatments on the chain dynamics and thermal stability of bovine pericardium collagen

A new approach for the replacement of heart valves consists of obtaining an acellular matrix from animal aortic valves that performs mechanically, is nonantigenic, and is free from calcification and fibroblast proliferation. Novel biochemical treatments must be developed for this purpose. In this work, we focus on the characterization of collagen in acellular bovine cardiovascular tissues, fresh or glutaraldehyde treated, and stored in different solutions [phosphate-buffered saline (PBS), ethanol, octanol, and glutaraldehyde], to determine whether the resulting fibrous material is structurally preserved. The preservation of the triple helical structure of collagen is checked by differential scanning calorimetry (DSC), which is a well suited technique to analyze thermal transitions in proteins, such as denaturation. To get insight into the molecular dynamics of collagen in the nanometric range, we used thermally stimulated currents, a dielectric technique running at low frequency, that measure the dipolar reorientations in proteins submitted to a static electrical field. The combined use of these two techniques allowed us to evaluate the physical structure and conformation of collagen after the different chemical treatments. We have found that the glutaraldehyde treatment followed by octanol storage preserves the triple helical conformation of the polypeptidic chains of collagen, contrary to the ethanol and PBS storage that induce drastic changes in the thermal and dielectric behavior of the protein. Moreover, this particular chemical treatment stabilizes the collagen structure (shift toward high temperature of the collagen denaturation and stiffening of the chains by a cross-linking action) when compared to the control sample, and so could provide interesting fibrous material for the conception of bioprosthetic heart valve.

Investigation of media formulations promoting differential antigen expression by Photobacterium damsela ssp. piscicida and recognition by sea bass, Dicentrarchus labrax (L.), immune sera

Photobacterium damsela ssp. piscicida (Phdp) isolates were grown in various bacteriological media, in eukaryotic cell culture media and in the presence of fish cells (resembling some aspects of in vivo growth environments). Bacterial cells, extracellular products (ECPs) and crude capsular polysaccharide were isolated and analysed by electrophoresis and Western blot using sea bass sera. Growth in bacteriological media conserved the synthesis of cell and extracellular components when these were compared with those prepared under near-in vivo growth conditions. In fact, synthesis of a larger range of cell components was induced after growth in bacteriological media. Certain media based on yeast extract and peptones from various sources and a specific salt formulation induced the synthesis of novel cell components at approximately 21.3 and 14 kDa. These antigens were recognized by sea bass sera collected after natural pasteurellosis outbreaks and other sea bass sera raised against live or inactivated Phdp cells. The ECPs of the pathogen were not good immunogens in their soluble form despite various treatments prior to immunization. The results are discussed with respect to vaccine development.

Structural characterisation of bisintercalation in higher-order DNA at a junction-like quadruplex

We report the single-crystal X-ray structure for the complex of the bisacridine bis-(9-aminooctyl(2-(dimethylaminoethyl)acridine-4-carboxamide)) with the oligonucleotide d(CGTACG)(2) to a resolution of 2.4A. Solution studies with closed circular DNA show this compound to be a bisintercalating threading agent, but so far we have no crystallographic or NMR structural data conforming to the model of contiguous intercalation within the same duplex. Here, with the hexameric duplex d(CGTACG), the DNA is observed to undergo a terminal cytosine base exchange to yield an unusual guanine quadruplex intercalation site through which the bisacridine threads its octamethylene linker to fuse two DNA duplexes. The 4-carboxamide side-chains form anchoring hydrogen-bonding interactions with guanine O6 atoms on each side of the quadruplex. This higher-order DNA structure provides insight into an unexpected property of bisintercalating threading agents, and suggests the idea of targeting such compounds specifically at four-way DNA junctions.

Crystal structures of acridines complexed with nucleic acids

Acridines have been used as chemotherapeutic agents against bacteria, protozoa and fungi, and they now find important use as anticancer drugs. There is a paucity of crystal structures of acridine-DNA complexes above the dinucleotide level, but recent structures of acridinecarboxamide topoisomerase II poisons complexed to hexanucleotides have allowed a molecular rationalization of their structure-activity relationships for cytotoxicity and for their kinetics of DNA binding.