Prehospital anaesthesia: a survey of current practice in the UK.

AIM: To establish the national picture of prehospital anaesthesia in the UK and to reference practice against the Association of prior to Anaesthetists of Great Britain and Ireland safety guideline on prehospital anaesthesia. METHODS: Lead clinicians were identified for all prehospital services in the UK that could potentially be performing prehospital anaesthesia and invited to complete a detailed online survey. The survey requested details on team structure, the process for prehospital anaesthesia, drugs and equipment used and training and governance arrangements. RESULTS: 55 responses were received from 63 invitations sent (87.3%) yielding usable data for 47 services. 31 of the 47 services (70%) responded that they performed prehospital anaesthesia. All services performing prehospital anaesthesia utilised a doctor but only 18 services (58%) always utilised a trained assistant. 28 services (90%) maintained a database and over half of services (55%) performed less than 20 prehospital anaesthetics annually. 23 services (74%) had a designated lead clinician for prehospital anaesthesia and 25 (81%) had a written difficult airway plan. 19 services (61%) had mandatory continual training requirements. CONCLUSIONS: The majority of services are currently complying with the recommendations in the Association of prior to Anaesthetists of Great Britain and Ireland safety guideline. There are still areas of concern, particularly with regard to ongoing training and the high numbers of services that do not use a trained assistant for the process of prehospital anaesthesia.

Expression of substrate-specific transporters encoded by Plasmodium falciparum in Xenopus laevis oocytes.

When the malarial parasite Plasmodium falciparum multiplies in erythrocytes it dramatically increases uptake of essential metabolic precursors (nucleosides, nucleobases and glucose) and export of lactic acid by undefined mechanisms. The first evidence is provided here, by a detailed study in Xenopus laevis oocytes, that several specific nutrient transporters are the product of P. falciparum genes. We report the expression of nucleoside, nucleobase, hexose and monocarboxylate transport systems in Xenopus oocytes when injected with mRNA isolated from asexual stages of developing P. falciparum parasites. Their properties are distinct from transport events occurring at the infected erythrocyte membrane or the electrophysiologically identified channel localised to the parasitophorous vacuolar membrane. These novel transporters are substrate-specific and stereoselective, and represent a key regulatory step in the acquisition and export of metabolites by intraerythrocytic P. falciparum.

Polymerase chain reaction for the detection of Burkholderia pseudomallei.

Melioidosis is a potentially lethal infection of humans and animals in Southeast Asia and northern Australia. Current methods for detection of the causative organism, Burkholderia pseudomallei, lack both speed and sensitivity. We report the development of a highly sensitive polymerase chain reaction-based method that can detect as few as 35 colony-forming units of B. pseudomallei/mL in saline suspensions. This polymerase chain reaction test also detected the presence of B. pseudomallei DNA in culture-negative splenic tissue obtained from mice infected with the organism, but without clinical evidence of disease. Specificity has been confirmed using a variety of pathogenic and nonpathogenic organisms, including B. mallei, B. cepacia, and Pseudomonas species. The clinical usefulness of this test should be assessed prospectively and compared with conventional diagnostic techniques.

Conservation of motifs within the unusually variable polypeptide sequences of type I restriction and modification enzymes.

Type I restriction enzymes comprise three subunits encoded by genes designated hsdR, hsdM, and hsdS; S confers sequence specificity. Three families of enzymes are known and within families, but not between, hsdM and hsdR are conserved. Consequently, interfamily comparisons of M and R sequences focus on regions of putative functional significance, while both inter- and intrafamily comparisons address the origin, nature and role of diversity of type I restriction systems. We have determined the sequence of the hsdR gene for EcoA, thus making available sequences of all three hsd genes of one representative from each family. The predicted R polypeptide sequences share conserved regions with one superfamily of putative helicases, so-called 'DEAD box' proteins; these conserved sequences may be associated with the ATP-dependent translocation of DNA that precedes restriction. We also present hsdM and hsdR sequences for EcoE, a member of the same family as EcoA. The sequences of the M and R genes of EcoA and EcoE are at least as divergent as typical genes from Escherichia coli and Salmonella, perhaps as the result of selection favouring diversity of restriction specificities combined with lateral transfer among different species.

Roles of selection and recombination in the evolution of type I restriction-modification systems in enterobacteria.

Restriction-modification systems can protect bacteria against viral infection. Sequences of the hsdM gene, encoding one of the three subunits of type I restriction-modification systems, have been determined for four strains of enterobacteria. Comparison with the known sequences of EcoK and EcoR124 indicates that all are homologous, though they fall into three families (exemplified by EcoK, EcoA, and EcoR124), the first two of which are apparently allelic. The extent of amino acid sequence identity between EcoK and EcoA is so low that the genes encoding them might be better termed pseudoalleles; this almost certainly reflects genetic exchange among highly divergent species. Within the EcoK family the ratio of intra- to interspecific divergence is very high. The extent of divergence between the genes from Escherichia coli K-12 and Salmonella typhimurium LT2 is similar to that for other genes with the same level of codon usage bias. In contrast, intraspecific divergence (between E. coli strains B and K-12) is extremely high and may reflect the action of frequency-dependent selection mediated by bacteriophages. There is also evidence of lateral transfer of a short sequence between E. coli and S. typhimurium.

Conservation of organization in the specificity polypeptides of two families of type I restriction enzymes.

We have identified the recognition sequence for the Citrobacter freundii restriction endonuclease CfrA, a member of the A-family of type I R-M enzymes. This bipartite target sequence differs in both its components from those of other type I enzymes. We determined the nucleotide sequence of its specificity gene (hsdS) and a comparison of this with its relative EcoA identifies two extensive variable regions, an organization analogous to that found in the K-family of type I R-M enzymes. The specificity polypeptides of the A-family, unlike those of K, have an N-terminal conserved region, and this includes a sequence repeated within the central conserved region. A second repeat sequence, identified at the amino acid level, coincides with the only sequence similarity common to all type I S polypeptides. Sequences immediately downstream from the hsdS genes of EcoA, CfrA, EcoK, B and D are almost identical, consistent with an allelic chromosomal location.

Dual infection of retina with human immunodeficiency virus type 1 and cytomegalovirus.

We examined retinal tissue from eight human immunodeficiency virus type 1 (HIV-1) seropositive patients with acquired immunodeficiency syndrome (AIDS) or AIDS-related complex for evidence of dual infection with HIV-1 and cytomegalovirus. Culture demonstrated simultaneous infection with HIV-1 and cytomegalovirus in two of 13 retinal specimens. This was confirmed by both immunofluorescence and immunohistochemical staining. Moreover, coinfection of individual cells with cytomegalovirus and HIV-1 was observed by immunohistochemical staining. Infection of retina with cytomegalovirus or HIV-1 alone occurred in one and six of the 13 retinal specimens, respectively. HIV-1 antigens were present on scattered cells in all layers of the retina and on retinal vascular endothelium. HIV-1 was isolated from retinal tissue derived from eyes both with and without gross ocular lesions. Cytomegalovirus antigens were found in all layers of the retina, but not on vascular endothelial cells. The atypically rapid clinical progression of retinitis in one of the patients with dual HIV-1 and cytomegalovirus infection suggests the possibility that interactions between these two viruses may influence retinal disease in patients with AIDS.

Conservation of complex DNA recognition domains between families of restriction enzymes.

One polypeptide, designated S, confers sequence-specificity to the multisubunit type I restriction enzymes. Two families of such enzymes, K and A, include members that recognize diverse, bipartite, target sequences. The S polypeptides of the K family, while having areas of near identity, also contain two extensive regions of variable sequence. We now show that one of these, comprising the N-terminal 150 amino acids, specifies recognition of one component of the bipartite target sequence. We have determined the sequence recognized by EcoE, a member of the A family. This sequence, 5'GAG(N7)ATGC, has the trinucleotide GAG in common with EcoA and with StySB of the K family. We determined the nucleotide sequences of the S genes of EcoA and EcoE, and compared their predicted amino acid sequences with each other and with those of the five members of the K family. There is no general sequence similarity between families, but the domain of the S polypeptide of StySB, which specifies GAG, shows nearly 50 per cent identity with the amino variable region of the S polypeptides of EcoA and EcoE. A complex domain that recognizes and directs methylation of GAG is therefore common to enzymes of generally dissimilar amino acid sequence.

Apparent disappearance of a macular hole associated with development of an epiretinal membrane.

A macular hole in a 78-year-old man participating in a long-term follow-up study changed its biomicroscopic appearance dramatically as a result of changes in an epiretinal membrane. The macular hole became invisible and visual acuity improved from 20/70-2 to 20/30-2+2.

EcoA and EcoE: alternatives to the EcoK family of type I restriction and modification systems of Escherichia coli.

The genes (hsd A) encoding EcoA, a restriction and modification system first identified in Escherichia coli 15T-, behave in genetic crosses as alleles of the genes (hsd K) encoding the archetypal type I restriction and modification system of E. coli K12. Nevertheless, molecular experiments have failed to detect relatedness between the A and K systems. We have cloned the hsd A genes and have identified, on the basis of DNA homology, related genes (hsd E) conferring a new specificity to a natural isolate of E. coli. We show that the overall organization of the genes encoding EcoA and EcoE closely parallels that for EcoK. Each enzyme is encoded by three genes, of which only one, hsdS, confers the specificity of DNA interaction. The three genes are in the same order as those encoding EcoK, i.e. hsdR, hsdM and hsdS and, similarly, they include a promoter between hsdR and hsdM from which the M and S genes can be transcribed. The evidence indicates that EcoA and EcoE are type I restriction and modification enzymes, but they appear to identify an alternative family to EcoK. For both families, the hsdR polypeptide is by far the largest, but the sizes of the other two polypeptides are reversed, with the smallest polypeptide of EcoK being the product of hsd S, and the smallest for the EcoA family being the product of hsdM. Physiologically, the A restriction and modification system differs from that of K and its relatives, in that A-specific methylation of unmodified DNA is particularly effective.

Immunotherapy of graft versus host disease with specific alloantiserum: restoration of cerebellar development in infant rats.

Fischer (FI) rats were stimulated to produce high-titre alloantiserum against DA antigens for alleviation of the symptoms of graft versus host disease (g.v.h.d.) in FI neonates. G.v.h.d. was procured by intravenous injection of DA lymph node cells on the day of birth. Daily injections of alloantiserum on postnatal days 11-13 not only prevented the progress of the disease in the whole animal but reversed the altered neuronal histogenesis that was present in diseased animals at day 11. Specifically, by 3 days after onset of alloantiserum treatment, the severely depressed DNA synthesis had returned to near normal levels. The decreased numbers of newly formed cells in the cerebellar cortex matrix area seen at day 11 was also reversed. For example, there was a significant increase in the number of newly formed basket and stellate cells in 14 day old alloantiserum-treated animals. G.v.h.d. did not result in a lymphocytic infiltration or an inflammatory response in the cerebellum. Therefore, we postulate that the deleterious effects of g.v.h.d. and the restoration effects of alloantiserum treatment are not directly cell-mediated. Rather, some soluble factor(s) interfering with the cerebellar cell cycle may be released during the interaction of donor lymphocytes and host cells at sites distant from the cerebellum. In support of this, in vitro analysis of DNA synthesis revealed that removal of cerebellar cells from the internal milieu of g.v.h.d. permitted DNA synthesis to proceed at a rate similar to that in control tissue.

Changes in the fluid compartments and dry weights of reimplanted dog lungs.

We studied changes in fluid compartments and dry weights of reimplanted lungs of dogs during the first 6 wk after operation. Excision and reimplantation caused a large increase in lung weight. The increase in weight was maximal 3 days after operation, was proportionately greater in the upper middle lobe than in the lower lobe, and was principally due to increased extravascular water. Dry weight and noncirculating red cells (measured by subtracting 51Cr-labeled red cell mass from total red cell mass as measured by hemoglobin extraction) also increased within 3 days after operation. Lung weight and extravascular water decreased progressively after 3 days and were normal in 6 wk. Chromated blood mass remaining within excised, passively drained lobes did not change at any stage postoperatively. Three days after operation, frozen lung sections showed minimal alveolar fluid but large amounts of peribronchial and perivascular edema which was occasionally blood tinged; submucosal edema was present in a few bronchi. Using intraalveolar Evans blue dye, we confirmed that several bronchial lymphatics close within 6 h and refenerate during the first postoperative week. Many of observed functional changes in freshly reimplanted lungs are temporally related to changes in extravascular water.