Flow changes in the aorta associated with the deployment of a AAA stent graft

The purpose of this study was to investigate the hemodynamic implications of a proximal shift in the aortic bifurcation that results from abdominal aortic aneurysm (AAA) stent graft deployment. A flow model was constructed in which an anatomically accurate model of the aorta was subjected to physiologic pulsatile flow. The model included the celiac, superior mesenteric, left and right renal arteries. The aortic bifurcation, leading to the right and left iliac arteries was included, as well as the lumbar curvature. Flow simulations were performed under resting and mild exercise conditions with and without a Cordis AAA stent graft deployed. Flow patterns were visualized with dye injection and recorded onto video. The flow rates through the iliac and renal arteries were continuously monitored using ultrasonic flowmeters. Flow visualization revealed that flow disturbances at the level of the renal arteries were slightly increased with the deployment of the stent graft. The orientation of the endolegs within the aorta had no perceptible effect on these disturbances. Under mild exercise conditions, very little flow disturbance was observed. In conclusion, there are slight changes in flow disturbance near the renal arteries due to stent graft deployment, but these changes would not be expected to have significant clinical implications.

Pasture forages, supplementation rate, and stocking rate effects on dairy cow performance

Objectives were to evaluate effects of forage species, stocking rate, and supplementation rate on performance and physiology of grazing lactating Holstein cows under intensive rotational stocking management during summer. Eight treatments were arranged in a 2 x 2 x 2 factorial design. Animals (n = 62) grazed pastures of Tifton 85 bermudagrass or Florigraze rhizoma peanut, a tropical legume. Low and high stocking rates were 7.5 and 10.0 cows/ha for bermudagrass and 5.0 and 7.5 cows/ha for rhizoma peanut. Within each forage-stocking rate combination, cows were fed supplement at 0.33 or 0.5 kg of supplement (as-fed basis)/kg daily milk production. Cows grazing rhizoma peanut pastures produced more milk (16.9 vs. 15.4 kg/d) but had higher rectal temperatures (39.4 vs. 39.1 degrees C). Milk production per cow was improved at the higher stocking rate for bermudagrass but was reduced at the higher stocking rate for peanuts. Increasing supplementation rate boosted plasma glucose, milk production, and milk protein percent. Increased supplementation rate had a greater positive impact on milk production of cows grazing bermudagrass compared to rhizoma peanut (21.9 vs. 10.6% increase) due to a lower substitution of grain for forage intake. Organic matter intakes of forage, supplement, and total diet were greatest by cows grazing rhizoma peanut pastures and averaged 12.4, 6.1, and 18.5 kg/d compared to 9.2, 5.4, and 14.6 kg/d for cows grazing bermudagrass. Despite lower individual feed intake and performance, production per unit land area was 29% greater (112 vs. 90 kg of milk/ha per d) for cows grazing bermudagrass due to the greater stocking rate possible with that forage. Only cows supplemented at the high rate and kept at the high stocking rate on bermudagrass maintained body weight. Cows on other treatments lost body weight. Tifton 85 bermudagrass appears to be an excellent summer forage for dairy cows grazing in the southeastern U.S. given its nutritive value characteristics and high yields. Optimum stocking rate may be as high as 10 cows/ha during times of peak growth of forage for low-to-moderately producing cows fed supplement. Furthermore, the positive milk production response to additional supplement when cows grazed Tifton 85 pastures (0.8 kg/kg of supplement), indicates the value of providing supplement to cows grazing this moderate quality forage.

Comparison of media for optimal recovery of Candida albicans and Candida glabrata from blood culture

BACKGROUND

Candida spp., mainly Candida albicans, are frequently responsible for complications in immunocompromised patients. There are limited data comparing recovery efficiency using simple non-selective basal broth media.

AIM

To compare several commercially available basal growth media to determine the medium that gave highest yeast proliferation.

METHOD

Eight commercially available non-selective basal broth culture media were evaluated for optimum recovery of clinical C. albicans and C. glabrata. They included nutrient broth (NB), nutrient broth no. 2 (NB2), Todd-Hewitt (TH) broth, tryptone soya broth (TSB), tryptone soya broth supplemented with yeast extract (0.5% w/v [TSBYE]), brain heart infusion broth supplemented with yeast extract (0.5% w/v [BHIYE]), salt meat broth (SMB) and 0.1% [w/v] peptone saline (PS). Differences in cell density were evaluated by spectrophotometrical analysis.

RESULTS

TSBYE>BHIYE>TSB>TH>NB2>NB>SMB>PS for the optimum proliferation of cells in vitro. Either TSBYE or BHIYE broth may be employed as suitable basal broth media for growth of C. albicans and C. glabrata. NB should be considered the least suitable medium for routine use when others are available.

CONCLUSION

These data may be of value to laboratories setting up simple blood culture systems to detect Candida spp., particularly in developing and underdeveloped countries.

Employment of broad-range 16S rRNA PCR to detect aetiological agents of infection from clinical specimens in patients with acute meningitis--rapid separation of 16S rRNA PCR amplicons without the need for cloning

AIMS

The aim of this study was to develop a polyacrylamide gel electrophoresis (PAGE) method for the rapid separation of 16S rRNA PCR amplicons from aetiological agents of acute meningitis.

METHODS AND RESULTS

Blood samples from 40 patients with suspected acute meningococcal meningitis were examined for the presence of causal agents, including Neisseria meningitidis employing two methods: (i) broad-range 16S rRNA PCR in conjunction with PAGE and automated sequencing and (ii) species-specific PCR employing ABI TaqMan technology for N. meningitidis. Analysis of clinical specimens employing 16S rRNA PCR yielded 33/40 (82.5%) positive for the presence of bacterial DNA. Species-specific PCR yielded 30/40 (75%) clinical specimens positive for N. meningitidis. Prior to separation by PAGE, only 6/33 (18.2%) amplicons were able to be identified by sequence analysis, the remaining amplicons (n=27) did not yield an identification due to the presence of mixed 16S rRNA PCR amplicons. Following separation, amplicons were re-amplified and sequenced, yielding 24/27 (88.9%) positive for N. meningitidis and three specimens positive for Acinetobacter sp., Staphylococcus aureus and Streptococcus pneumoniae. One specimen was positive for both N. meningitidis and Streptococcus spp. and another specimen was positive for N. meningitidis and Pseudomonas sp., by broad-range PCR. Seven clinical specimens were negative for N. meningitidis and other eubacteria using both detection techniques.

CONCLUSIONS

Clinical specimens including blood and cerebrospinal fluid from patients with suspected acute bacterial meningitis, may become contaminated with commensal skin flora, resulting in difficulties in downstream sequencing of pathogen plus contaminant DNA. This study allows for the rapid separation of amplified pathogen from contaminant DNA.

SIGNIFICANCE AND IMPACT OF STUDY

This study demonstrated the usefulness of the rapid separation of multiple 16S rRNA PCR amplicons using a combination of PAGE and automated sequencing, without the need of cloning. Adoption of this technique is therefore proposed when trying to rapidly identify pathogens in clinical specimens employing broad-range 16S rRNA PCR.

A comparison of pulmonary exacerbations with single and multiple organisms in patients with cystic fibrosis and chronic Burkholderia cepacia infection

STUDY OBJECTIVES

To compare pulmonary exacerbations with single and multiple organisms in patients with chronic Burkholderia cepacia infection.

DESIGN

Data was collected over a 23-month period and for each of the patients two episodes of pulmonary exacerbation were identified, one with B. cepacia isolated as the sole respiratory pathogen and the other with one or more coinfecting organisms grown from the sputum culture.

SETTING

Regional tertiary referral center for Respiratory Medicine and Adult Cystic Fibrosis Center for Northern Ireland, Belfast City Hospital.

PATIENTS

Adult (over 16 years) CF patients with chronic (more than 4 years) B. cepacia complex infection who attended the Belfast City Hospital between January 1997 and November 1998.

MEASUREMENTS

Forced expiratory volume in 1s, forced vital capacity, forced expiratory flow rate 25-75, C-reactive protein, leucocyte count and body mass index were measured before and after two weeks of treatment and analysed for any differences in change between the two episodes.

RESULTS

All variables in both groups improved following treatment except for body mass index, which remained unchanged. No significant differences between the measurements were identified on comparison of single (monomicrobial) and multiple (polymicrobial) isolate episodes.

CONCLUSION

Patients with chronic B. cepacia infection who develop a pulmonary exacerbation improve, as reflected by clinical and biochemical markers, following IV antibiotic treatment. Pulmonary exacerbations with multiple organisms are no more severe than those where only B. cepacia is isolated.

Biohazards and ecotoxicological considerations of landspreading of spent compost wastes

Spent mushroom compost (SMC) is a major waste of the mushroom industry with low economic value. SMC arises after mushroom production in phase II compost (pIIC), predominantly comprising straw and chicken litter as principal raw ingredients. The majority of SMC waste is disposed off by application to agricultural land. It is an attractive proposition for utilising SMC as soil inorganic fertiliser supplementation. However, there is limited data available as to the consequences of this method of disposal either in terms of microbiological loading of food-borne pathogens and those of concern to mushroom industry itself. The resulting imbalance of the natural flora of the agricultural land has not been properly audited. This study aims to initially examine SMC for prevalence of faecal bacterial pathogens including Campylobacter spp., Salmonella spp. and Listeria monocytogenes that may arise from chicken litter. At another level, it aims to ascertain the pathogenic bacteria (Pseudomonas syringae, pv phaseolicola or tolasii) and fungal populations (Trichoderma, Verticillium species) originating mainly from the straw component of the SMC, which are of concern to the mushroom industry. Lastly, the study would also qualitatively identify the diversity of bacterial populations within SMC. This was largely accomplished through employment of rDNA, PCR and direct sequencing strategies on the culturable microflora. However, for specific mushroom pathogens, nucleic acids (DNA or RNA) were directly extracted from composts before subjecting to sequence analysis. In accordance with the current legislation (ABP 02/02, Animal By Products wastes disposal EC No. 1774/2002), it is imperative to regulate the farm wastes carrying residues from animal sources including SMC before they are regarded safe for land spreading operations. The ecological microbe-microbe and plant-microbe interactions that potentially occur between the native bacterial soil flora and those added annually (approximately 10(18) cells) needs to be reviewed with caution. The above study highlights the ecological consequences involved in the disposal of SMC wastes on agricultural land and its implications for plant, animal and human health.

flaA-like sequences containing internal termination codons (TAG) in urease-positive thermophilic Campylobacter isolated in Japan

AIMS

To demonstrate two flaA-like sequences containing two internal termination codons (TAG) in two Japanese strains of urease-positive thermophilic Campylobacter (UPTC).

METHODS AND RESULTS

A primer pair of A1 and A2, which ought to generate a product of approx. 1700 bp of the flaA gene for Campylobacter jejuni, was used to amplify products of approx. 1450 bp for two Japanese strains of UPTC, CF89-12 and CF89-14. After molecular cloning and sequencing, the nucleotide sequences of the amplicons from the two strains were found to be 1461 bp in length and to have nucleotide sequence differences in relation to each other at four nucleotide positions, respectively.

CONCLUSIONS

Nucleotide and amino acid sequence alignment and homology analysis demonstrated that the polymerase chain reaction (PCR) amplicons from the two Japanese strains have approx. 83% nucleotide and 80% amino acid sequence homology to the possible open reading frame of the flaA gene of UPTC NCTC 12892.

SIGNIFICANCE AND IMPACT OF THE STUDY

Surprisingly, both PCR amplicons from the Japanese UPTC have two internal termination codons (TAG) at nucleotide positions from 775 to 777 and 817 to 819, respectively.

Molecular diversity of Campylobacter coli and C. jejuni isolated from pigs at slaughter by flaA-RFLP analysis and ribotyping

A population of porcine isolates of Camplobacter jejuni (n = 11) and C. coli (n = 17) were examined for genotypic relatedness employing ribotyping, as well as polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of the flagellin (fla)A gene locus. PCR was employed to amplify a 533 bp fragment from the flaA gene, including the previously described short variable region (SVR), employing the novel primers, A2 and Al and successfully generated this amplicon for all wild-type strains examined (n = 28) of both C. jejuni and C. coli, as well as with both type strains, i.e. C. jejuni NCTC 11351 and C. coli NCTC 11366. Individual genotypes were assigned to each isolate typed employing the four typing methods (flaA-RFLP(Hae) III, flaA-RFLP(Pst) I ribotyping(Hae) III and ribotyping(Pst) I) and were assigned an arbitrary genotype code in ascending alphabetical order in comparison with a database of established genotypes for each of the methods employed. This study showed that several flaA-RFLP and ribopatterns existed within C. jejuni and C. coli, and demonstrated a heterogeneous diversity of strains occurring in the pigs examined. Ribotyping of strains with 16S and 23S rRNA with Pst I and Hae III digested chromosomal DNA allowed subdivision of strains into nine and eight groups, respectively. RFLP analyses with Pst I and Hae III digests probed with the flaA gene probe allowed subdivision of strains into eight and eleven subtypes, respectively. Employment of RFLP with the flaA nucleic acid probe and Hae III digests produced the greatest amount of variation of any genotyping scheme employed. Although there was a high degree of variability demonstrated by both typing methods, most isolates ( > 60%) clustered into four main genotypes, i.e. genotypes A-D. FlaA-PCR-RFLP typing demonstrated that the majority of isolates, 67.9 and 60.7%, were included in these four main genotypes for Pst I and Hae III restriction digests, respectively, although there was a high prevalence (7/11; 63.6%) of fla(Hae) III genotype A occurring within the C. jejuni isolates. Likewise, ribotyping studies demonstrated that most isolates were clustered into these four main genotypes, accounting for 81.5 and 60.7% of isolates for Pst I and Hae III restriction digests, respectively. This may indicate that the clonal population of campylobacters within this pig population is largely composed of persistent and dominant types, with a smaller number of hypervariable subtypes. Such data may useful in determining epidemiological routes of transmission of campylobacters from animal to animal, as well as helping to identify virulence determinants in persistent subtype populations.

Comparison of API20C with molecular identification of Candida spp isolated from bloodstream infections

A study was carried out to compare the API20C technology with polymerase chain reaction amplification and direct sequencing of the short internal transcribed spacer region 2 (ITS2) for the identification of 58 isolates of invasive candida species obtained from patients with bloodstream infections over the seven year period 1994 to 2000. Overall, there was only one disagreement between the phenotypic and genotypic identification, where the API scheme identified the isolate as C albicans but the molecular method identified it as C dubliniensis. This study demonstrated that the API20C method is useful in the identification of Candida spp isolated from blood culture and that molecular methods do not enhance identifications made using the API20C scheme. However, for correct reporting of C dubliniensis, an emerging bloodborne pathogen, it is recommended that all isolates identified as C albicans by the API20C scheme are further examined phenotypically and/or genotypically.

Cloning and sequencing of 16S rDNA and 16S-23S rDNA internal spacer region (ISR) from urease-positive thermophilic Campylobacter (UPTC)

AIMS

To clone and sequence the 16S rDNA and 16S-23S rDNA internal spacer region (ISR) from urease-positive thermophilic Campylobacter (UPTC).

METHODS AND RESULTS

The primer sets for 16S rDNA and 16S-23S rDNA ISR amplified almost the full length of 16S rDNA and 16S-23S rDNA ISR. About 1500 bp for 16S rDNA and about 720 bp for 16S-23S rDNA ISR of the rrn operon of four strains of UPTC were identified after molecular cloning and sequencing.

CONCLUSIONS

The four strains and CCUG18267 of UPTC showed approximately 99% sequence homology of 16S rDNA to each other, 96-97% to Camp. coli, 97-98% to Camp. jejuni and 97-98% to Camp. lari.

SIGNIFICANCE AND IMPACT OF THE STUDY

For the first time, the nucleotide sequence of 16S-23S rDNA ISR of UPTC has been analysed. The sequence of ISR was almost identical among the four strains of UPTC. It is interesting that the UPTC intercistronic tRNAs demonstrated an order of tRNA of 5'-16S-tRNAAla-tRNAIle-23S-3' in the organisms.

Molecular epidemiology of cystic fibrosis-linked Burkholderia cepacia complex isolates from three national referral centres in Ireland

AIMS

Burkholderia cepacia is a Gram-negative bacterium associated with increasing morbidity and mortality and is readily transmitted among infected cystic fibrosis (CF) patients. The B. cepacia complex consists of five distinct subgroups, termed genomovars. A collection of 17 presumptive B. cepacia isolates, obtained from three national CF referral centres located in different geographical regions in Ireland, was studied. The aim of this study was to investigate these isolates using molecular subtyping protocols for evidence of genetic relationships and for the presence of antibiotic resistance-encoding class 1 integron structures.

METHODS AND RESULTS

Genomovar classifications were assigned to each isolate based on HaeIII enzyme profiles of their recA locus. Genetic relationships among this collection were also assessed after restriction fragment length polymorphism (RFLP)-mediated analysis of the 16S rDNA locus and DNA amplification fingerprinting (DAF). The surface expression of the cable pilus gene (cblA) may facilitate an early step in the infection process. All isolates were tested by amplification strategies for this marker. Burkholderia cepacia is known to be resistant to several antimicrobial agents. Resistance typing showed that the majority were resistant to three or more common antimicrobial agents. Five of the 17 isolates were resistant to sulphonamide, a characteristic linked with the presence of class 1 integrons. Gene cassettes containing beta-lactamase (oxa) and aminoglycoside acetyltransferase (aac(6')-1a) encoding genes were identified by polymerase chain reaction amplification.

CONCLUSIONS

Most of the isolates in this study were classified as genomovar III and were indistinguishable based on their corresponding 16S rDNA-RFLP profiles, whilst DAF further subtyped the collection. The cblA marker was identified in 47% of the isolates, many of which clustered in the genomovar III group. Class 1 integrons with recombined gene cassettes containing bla-OXA and aac(6')-1a genes were identified.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study demonstrates the application of molecular methods to investigate B. cepacia, a well-recognized human pathogen, cultured from Irish CF patients. Genomovar III was the most common genomic type identified. DNA fingerprinting further subtyped the latter isolates, facilitating a more detailed description of the molecular epidemiology. Drug resistance in these organisms can be explained, at least in part, by the presence of class 1 integrons. Development of targeted infection control strategies could be facilitated using these applied methods.

Molecular genotyping of isolates of Actinobacillus actinomycetemcomitans by pulsed-field gel electrophoresis after separate digestion with Sse8387I and XhoI

Genomic DNA from 18 Japanese clinical isolates of Actinobacillus actinomycetemcomitans was obtained from six periodontitis patients and analyzed using pulsed-field gel electrophoresis (PFGE) after separate digestion with Sse8387I and with XhoI. Three isolates from an identical patient were found to share an identical PFGE profile, and isolates from distinct patients were found to have PFGE profiles distinctly different from each other. Consequently, the 18 Japanese clinical isolates were discriminated into six distinct genotypes by means of PFGE. The genomic DNA from the other six reference strains (ATCC33384, ATCC43717, ATCC 43718, JCM2434, JCM2435 and Nig-1) was discriminated into six genotypes by the same PFGE methodology, and these six genotypes were found to be distinctly different from the six genotypes of the 18 Japanese clinical isolates described above. Serotyping demonstrated three PFGE genotypes in the serotype a strains, four the serotype b strains and three the serotype c strains. The present results clearly suggest that the PFGE procedure after separate digestion with Sse8387I and with XhoI has an excellent discriminatory power amongst strains and has a good genotypability for A. actinomycetemcomitans.

Trends in the epidemiology of Candida bloodstream infections in Northern Ireland between January 1984 and December 2000

OBJECTIVE

To describe the epidemiology of Candida bloodstream infections (BSI) in Northern Ireland.

METHODS

Retrospective collation of data relating to all clinically significant BSI in a university teaching hospital, which had been recorded prospectively, between 1984 and 2000.

RESULTS

One hundred and forty five episodes of candidaemia occurred in 144 patients (of mean age 56.6 years). The contribution of Candida spp. towards all significant BSI increased from 2.0% to 2.5%. C. albicans was the most frequently isolated species, however, its incidence fell from 70% to 53% during the study period. The greatest increase in incidence was seen with C. glabrata which was the most common non-albicans species. Twenty-nine per cent of isolates occurred in patients from an intensive care unit and, surprisingly, a further 25.5% occurred in patients from a surgical service.

CONCLUSION

There appears to be several subtle differences in the epidemiology of candidal BSI between Northern Ireland and other countries.

A novel mutation in KRT12 associated with Meesmann's epithelial corneal dystrophy

BACKGROUND

The molecular basis of Meesmann's epithelial corneal dystrophy (MECD) has recently been attributed to mutations in the cornea specific keratin genes KRT3 and KRT12. The mechanisms by which these mutations cause the Meesmann's phenotype are not clear. This study presents new data, examines clinical, histological, ultrastructural, and molecular aspects of MECD, and compares the features seen in this condition with those observed in other well studied keratin diseases such as epidermolysis bullosa simplex.

METHODS

A two generation family with typical features of Meesmann's epithelial corneal dystrophy (MECD) was studied. All family members were examined under a slit lamp. Biopsy material from elective keratoplasty was studied by histopathological and ultrastructural analysis using standard techniques. Direct automated sequencing of genomic DNA was used for mutation detection, mutations were confirmed by restriction digest analysis.

RESULTS

The abnormal corneal epithelium was acanthotic and contained numerous dyskeratotic cells and intraepithelial vesicles. By electron microscopy abnormally aggregated and clumped keratin filament bundles were detected in basal and suprabasal keratinocytes from the centre of the cornea. Direct sequencing of the patients' genomic DNA revealed a novel missense mutation (423T>G) in exon 1 of the cornea specific keratin 12 (KRT12) gene. This mutation predicts the amino acid change N133K within the helix initiation motif of the K12 polypeptide. Comparative studies with well established keratin disorders of other human epithelia underscore the pathogenic relevance of K3 and K12 gene mutations in Meesmann's epithelial corneal dystrophy. The morphological data presented here illustrate the disruptive effects of keratin gene mutations on the integrity of corneal keratinocytes.

CONCLUSIONS

A clinical, histopathological, and ultrastructural study of a previously unreported family with MECD is presented. In this family the disease is ascribed to a novel mutation in KRT12. A molecular mechanism is proposed for MECD based on the comparison with other well characterised keratin diseases.

The corneal epithelial stem cell

The aim of this paper was to develop a GFP-expressing transgenic mouse model for the keratoepithelioplasty and to use this to follow the outcome of this form of graft, when placed on an inflamed corneal surface. Further aims were to characterize both the graft and the epithelial surface of the mouse and rat cornea using putative stem cell markers (P63 and Telomerase) and marker of cell differentiation (14-3-3 sigma). Keratepithelioplasty was carried out using a GFP transgenic mouse cornea as donor tissue. Fluorescent epithelial outgrowth from each keratepithelioplasty was scored and quantified. Donor corneal graft tissue was obtained from the paracentral region or the anatomical limbal region of murine corneas. Paracentral donor grafts (n = 20) consistently demonstrated a significant increase in proliferative potential compared to grafts obtained from the anatomical limbal region of the mouse cornea (n = 25) (P = 0.000, Mann-Whitney U). Correspondingly, P63 expression was maximal in the paracentral region of the mouse cornea, in keeping with the demonstrated increased proliferative potential of donor grafts harvested from this region of the cornea. The murine corneal epithelium demonstrated decreased rather than increased cellular layers at the limbal region, in contrast to that of the rat or human epithelium. In addition, as a general finding in all species tested, there was an apparent increase noted in P63 expression in basal corneal epithelial cells in regions that had increased cellular layers (limbus in humans and rats and the paracentral corneal region in the mouse). Epithelium, which had migrated from donor grafts onto recipient corneas, retained P63 expression for the period of time examined (up to 3 days postengraftment). In addition, the conjunctival surface of an injured conjunctivalized displayed an abnormal pattern of P63 expression. Telomerase expression was widespread throughout many layers of both the murine and rat corneal epithelium. In the mouse and rat corneal epithelium P63 expression was maximal in areas of increased proliferative potential. Its expression, however, was not confined to stem cells alone. Migrating cells from transplanted keratoepithelial grafts retained P63 expression at least in the early stages post-transplantation. Finally, damaged conjunctivalized corneas displayed an abnormal P63 expression pattern when compared to either normal conjunctiva or normal cornea.

Mycobacterium triplex pulmonary infection in an immunocompetent patient

We present the case of a 47-year-old immunocompetent patient with clinical evidence of pulmonary mycobacterial disease which was found to be due to Mycobacterium triplex. This novel organism is an uncommon, emerging, pathogen for which few reports of clinical infection exist in the medical literature.