[Anatomical study of pelvic colon]. / Étude anatomique du côlon pelvien.

OBJECTIVES: Identifying the different kinds of anatomical sigmoid colon in our environment and determine what exposes the most to the occurrence of pelvic colon volvulus. MATERIALS AND METHODS: This is a transverse prospective study from 1 January 2007 to 31 December 2012 on a series of 63 patients (33 men and 30 women) who underwent laparotomy for non-colonic pathologies. For all patients, the following parameters were recorded: C1: total length of the pelvic colon; C2: the length of the root of the meso-sigmoid; C3: the height of the meso-sigmoid; C4: maximum width of the meso-sigmoid. RESULTS: C1 through the entire series was 61,3cm. C2 average was 5.5cm. C3 height and maximum width C4 were on average 14,6cm and 7.6cm, respectively. Comparison of parameters in men and women showed no significant difference. CONCLUSION: This study allows us to know the different types of pelvic colons among the population of our operated patients. The measurements performed on the pelvic colon of patients presenting volvulus will help to attribute objectively the true authorship of this surgical emergency to an anatomical type of pelvic colon.

The complete genome sequence and analysis of Corynebacterium diphtheriae NCTC13129.

Corynebacterium diphtheriae is a Gram-positive, non-spore forming, non-motile, pleomorphic rod belonging to the genus Corynebacterium and the actinomycete group of organisms. The organism produces a potent bacteriophage-encoded protein exotoxin, diphtheria toxin (DT), which causes the symptoms of diphtheria. This potentially fatal infectious disease is controlled in many developed countries by an effective immunisation programme. However, the disease has made a dramatic return in recent years, in particular within the Eastern European region. The largest, and still on-going, outbreak since the advent of mass immunisation started within Russia and the newly independent states of the former Soviet Union in the 1990s. We have sequenced the genome of a UK clinical isolate (biotype gravis strain NCTC13129), representative of the clone responsible for this outbreak. The genome consists of a single circular chromosome of 2 488 635 bp, with no plasmids. It provides evidence that recent acquisition of pathogenicity factors goes beyond the toxin itself, and includes iron-uptake systems, adhesins and fimbrial proteins. This is in contrast to Corynebacterium's nearest sequenced pathogenic relative, Mycobacterium tuberculosis, where there is little evidence of recent horizontal DNA acquisition. The genome itself shows an unusually extreme large-scale compositional bias, being noticeably higher in G+C near the origin than at the terminus.

15-year follow-up results of the hydroxyapatite ceramic-coated femoral stem.

PURPOSE: To evaluate the clinical and radiological outcomes following implantation of the Furlong hydroxyapatite ceramic-coated femoral stem in total hip arthroplasty. METHODS: A longitudinal cohort of 116 consecutive patients (134 hips) was followed up prospectively. The follow-up period was at least 13 years (range, 13- 15 years). Clinical and radiological assessments were made using the Merle d'Aubigne and Postel score and Engh score for fixation and stability, respectively. Osteointegration was assessed radiographically by examining the bone implant interface using the method described by Gruen. RESULTS: 22 patients died during the study period and 6 were lost to follow-up. The respective mean Merle d'Aubigne and Postel scores for pain, range of movement, and ability to walk were 2.2, 2.8, and 2.4 preoperatively and 5.8, 4.8, and 5.4 postoperatively. Engh described satisfactory bony ongrowth as 10 points or more; the mean Engh score for fixation and stability was 24.7 (fixation=10, stability=14.7). One femoral stem was revised for a periprosthetic fracture caused by a fall, but none was revised for loosening. This gave a 99% survival at 13 years (95% confidence interval 94-100). CONCLUSION: The long-term results of this hydroxyapatite ceramic-coated femoral prosthesis are very satisfactory.

Prevalence and surgical significance of a high-origin anterior tibial artery.

PURPOSE: To assess the prevalence of proximal high-origin anterior tibial artery and its surgical significance. METHODS: 100 knees were prospectively studied using colour Doppler ultrasonography. No patient had a history of lower-limb arterial pathology or previous knee surgery. All ultrasound images were assessed by a single experienced vascular technician to eliminate inter-observer variability. RESULTS: The mean age of the patients was 56 years (range, 21-96 years). Prevalence of the high-origin anterior tibial arterial pattern was 6%, greater than that reported by previous angiographic or cadaveric studies. In all patients with high-origin anterior tibial artery, the artery was in direct contact with the posterior cortex of the tibia. CONCLUSION: This highlights the danger of using sharp instruments in knee procedures that involve extension of osteotomy to the posterior tibial cortex, particularly high-tibial osteotomy and total knee replacement. Knowledge of the anatomical variations in the branching of the popliteal artery is important because damage to its branches can be limb- or life-threatening.

Surprising fidelity of template-directed chemical ligation of oligonucleotides.

BACKGROUND: Nucleic acid replication via oligonucleotide ligation has been shown to be extremely prone to errors. If this is the case, it is difficult to envision how the assembly and replication of short oligonucleotides could have contributed to the origin of life and to the evolution of a putative RNA world. In order to assess the fidelity of oligonucleotide replication more accurately, chemical ligation reactions were performed with constant-sequence DNA templates and random-sequence DNA pools as substrates. RESULTS: In keeping with earlier results, constant-sequence hairpin templates were not faithfully copied by random-sequence substrates. Linear templates, however, showed exceptional replication fidelity, particularly when random hexamers were ligated at 25 degrees C. Surprisingly, at low temperatures the formation of G.A base pairs was common and sometimes occurred even more readily than the formation of the corresponding Watson-Crick A-T and G-C base pairs. CONCLUSIONS: The fidelity of ligation reactions increases with temperature and decreases with the length of the random-sequence substrates. Oligonucleotides with a defined sequence can be copied faithfully in the absence of enzymes. Thus, to the extent that short oligonucleotides could readily have been generated by prebiotic mechanisms, it is possible that the earliest self-replicators arose via oligonucleotide ligation.

Results of a hydroxyapatite-coated (Furlong) total hip replacement: a 13- to 15-year follow-up.

We describe the survival of 134 consecutive JRI Furlong hydroxyapatite-coated uncemented total hip replacements. The mean follow-up was for 14.2 years (13 to 15). Patients were assessed clinically, using the Merle d'Aubigné and Postel score. Radiographs were evaluated using Gruen zones for the stem and DeLee and Charnley zones for the cup. Signs of subsidence, radiolucent lines, endosteal bone formation (spot welds) and pedestal formation were used to assess fixation and stability of the stem according to Engh's criteria. Cup angle, migration and radiolucency were used to assess loosening of the cup. The criteria for failure were revision, or impending revision because of pain or loosening. Survival analysis was performed using a life table and the Kaplan-Meier curve. The mean total Merle d'Aubigné and Postel score was 7.4 pre-operatively and 15.9 at follow-up. During the study period 22 patients died and six were lost to follow-up. None of the cups was revised. One stem was revised for a periprosthetic fracture following a fall but none was revised for loosening, giving a 99% survival at 13 years. Our findings suggest that the long-term results of these hydroxyapatite-coated prostheses are more than satisfactory.

A safe zone for the passage of screws through the posterior tibial cortex in tibial tubercle transfer.

In tibial tubercle transfer, surgery drills and screws can put the popliteal vessels at risk if the posterior cortex is breached. This complication can be devastating. We have looked at arteriograms of 50 knees and identified a safe zone through which an instrument can be passed with more confidence. In our study we found no vessels directly posterior to the supero-medial aspect of the proximal metaphysis in any knee. Whilst care must still be taken, this area will allow surgeons greater confidence to obtain a stronger bicortical hold with any fixation device.

The decaying genome of Mycobacterium leprae.

Everything that we need to know about Mycobacterium leprae, a close relative of the tubercle bacillus, is encrypted in its genome. Inspection of the 3.27 Mb genome sequence of an armadillo-derived Indian isolate of the leprosy bacillus identified 1,605 genes encoding proteins and 50 genes for stable RNA species. Comparison with the genome sequence of Mycobacterium tuberculosis revealed an extreme case of reductive evolution, since less than half of the genome contains functional genes while inactivated or pseudogenes are highly abundant. The level of gene duplication was approximately 34% and, on classification of the proteins into families, the largest functional groups were found to be involved in the metabolism and modification of fatty acids and polyketides, transport of metabolites, cell envelope synthesis and gene regulation. Reductive evolution, gene decay and genome downsizing have eliminated entire metabolic pathways, together with their regulatory circuits and accessory functions, particularly those involved in catabolism. This may explain the unusually long generation time and account for our inability to culture the leprosy bacillus.

Comparing wound complication rates following closure of hip wounds with metallic skin staples or subcuticular vicryl suture: a prospective randomised trial.

PURPOSE: To compare 2 methods of wound closure-metallic staples or 3-0 undyed vicryl-according to postoperative wound complication rates. METHODS: Patients who underwent surgery for proximal femoral fractures were randomised to have wound closure with metallic staples or with subcuticular vicryl suture. Wounds were regularly examined postoperatively and only those with positive wound swabs were regarded as wound infections. RESULTS: Five infections and one superficial wound dehiscence occurred in the patients who had wound closure with metallic staples. The complication rate was significantly higher for this group compared with the group who had wound closure with subcuticular vicryl suture (p<0.025). CONCLUSION: Superficial wound complication rates are higher for wounds closed with metallic staples compared to wounds closed with subcuticular vicryl.

Accuracy of hand-held ultrasound scanning in detecting meniscal tears.

The diagnosis of a meniscal tear may require MRI, which is costly. Ultrasonography has been used to image the meniscus, but there are no reliable data on its accuracy. We performed a prospective study investigating the sensitivity and specificity of ultrasonography in comparison with MRI; the final outcome was determined at arthroscopy. The study included 35 patients with a mean age of 47 years (14 to 73). There was a sensitivity of 86.4% (95% confidence interval (CI) 75 to 97.7), a specificity of 69.2% (95% CI 53.7 to 84.7), a positive predictive value of 82.6% (95% CI 70 to 95.2) and a negative predictive value of 75% (95% CI 60.7 to 81.1) for ultrasonography. This compared favourably with a sensitivity of 86.4% (95% CI 75 to 97.7), a specificity of 100.0%, a positive predictive value of 100.0% and a negative predictive value of 81.3% (95% CI 74.7 to 87.9) for MRI. Given that the sensitivity matched that of MRI we feel that ultrasonography can reasonably be applied to confirm the clinical diagnosis before undertaking arthroscopy. However, the lower specificity suggests that there is still a need to improve the technique to reduce the number of false-positive diagnoses and thus to avoid unnecessary arthroscopy.

The fidelity of template-directed oligonucleotide ligation and the inevitability of polymerase function.

The first living systems may have employed template-directed oligonucleotide ligation for replication. The utility of oligonucleotide ligation as a mechanism for the origin and evolution of life is in part dependent on its fidelity. We have devised a method for evaluating ligation fidelity in which ligation substrates are selected from random sequence libraries. The fidelities of chemical and enzymatic ligation are compared under a variety of conditions. While reaction conditions can be found that promote high fidelity copying, departure from these conditions leads to error-prone copying. In particular, ligation reactions with shorter oligonucleotide substrates are less efficient but more faithful. These results support a model for origins in which there was selective pressure for template-directed oligonucleotide ligation to be gradually supplanted by mononucleotide polymerization.

ntn genes determining the early steps in the divergent catabolism of 4-nitrotoluene and toluene in Pseudomonas sp. strain TW3.

Pseudomonas sp. strain TW3 is able to oxidatively metabolize 4-nitrotoluene and toluene via a route analogous to the upper pathway of the TOL plasmids. We report the sequence and organization of five genes, ntnWCMAB*, which are very similar to and in the same order as the xyl operon of TOL plasmid pWW0 and present evidence that they encode enzymes which are expressed during growth on both 4-nitrotoluene and toluene and are responsible for their oxidation to 4-nitrobenzoate and benzoate, respectively. These genes encode an alcohol dehydrogenase homolog (ntnW), an NAD+-linked benzaldehyde dehydrogenase (ntnC), a two-gene toluene monooxygenase (ntnMA), and part of a benzyl alcohol dehydrogenase (ntnB*), which have 84 to 99% identity at the nucleotide and amino acid levels with the corresponding xylWCMAB genes. The xylB homolog on the TW3 genome (ntnB*) appears to be a pseudogene and is interrupted by a piece of DNA which destroys its functional open reading frame, implicating an additional and as-yet-unidentified benzyl alcohol dehydrogenase gene in this pathway. This conforms with the observation that the benzyl alcohol dehydrogenase expressed during growth on 4-nitrotoluene and toluene differs significantly from the XylB protein, requiring assay via dye-linked electron transfer rather than through a nicotinamide cofactor. The further catabolism of 4-nitrobenzoate and benzoate diverges in that the former enters the hydroxylaminobenzoate pathway as previously reported, while the latter is further metabolized via the beta-ketoadipate pathway.

The search for missing links between self-replicating nucleic acids and the RNA world.

The notion that modern metabolism was derived from a complex 'RNA world' in which most reactions were catalyzed by ribozymes has received wide acceptance. However, the evolutionary links between the first self-replicating systems and ribozymes as complex as, say, the Group I self-splicing intron or the HDV ribozyme, have remained elusive. While prebiotic chemists have succeeded in synthesizing short oligonucleotides, it is not immediately obvious how these could have replicated and evolved to the point where they could assume complex shapes and catalytic functions. Nonetheless, recent experiments from a variety of disciplines suggest a plausible pathway from prebiotic chemistry to complex metabolism, and this review is intended as a hypothetical roadmap for the origin and subsequent evolution of life.

Thiophosphorylation of histidine.

The preparation of a novel phosphorus species, thiophosphoramidate, has enabled the specific thiophosphorylation of histidine at its 3-position. The rates of phosphorylation and thiophosphorylation of histidine are reported, as well as the spectroscopic properties of both thiophosphoramidate and 3-thiophosphohistidine. Structural assignment of the latter was made by analogy to the NMR properties of the known 3-phosphohistidine. The alkylation of 3-thiophosphohistidine by phenacyl bromide serves as a model for the introduction of labeling or probe reagents into histidine phosphorothioate-containing proteins.

Cloning and expression of ntnD, encoding a novel NAD(P)(+)-independent 4-nitrobenzyl alcohol dehydrogenase from Pseudomonas sp. Strain TW3.

Pseudomonas sp. strain TW3 is able to metabolize 4-nitrotoluene to 4-nitrobenzoate and toluene to benzoate aerobically via a route analogous to the upper pathway of the TOL plasmids. We report the cloning and characterization of a benzyl alcohol dehydrogenase gene (ntnD) which encodes the enzyme for the catabolism of 4-nitrobenzyl alcohol and benzyl alcohol to 4-nitrobenzaldehyde and benzaldehyde, respectively. The gene is located downstream of the previously reported ntn gene cluster. NtnD bears no similarity to the analogous TOL plasmid XylB (benzyl alcohol dehydrogenase) protein either in its biochemistry, being NAD(P)(+) independent and requiring assay via dye-linked electron transfer, or in its deduced amino acid sequence. It does, however, have significant similarity in its amino acid sequence to other NAD(P)(+)-independent alcohol dehydrogenases and contains signature patterns characteristic of type III flavin adenine dinucleotide-dependent alcohol oxidases. Reverse transcription-PCR demonstrated that ntnD is transcribed during growth on 4-nitrotoluene, although apparently not as part of the same transcript as the other ntn genes. The substrate specificity of the enzyme expressed from the cloned and overexpressed gene was similar to the activity expressed from strain TW3 grown on 4-nitrotoluene, providing evidence that ntnD is the previously unidentified gene in the pathway of 4-nitrotoluene catabolism. Examination of the 14.8-kb region around the ntn genes suggests that one or more recombination events have been involved in the formation of their current organization.

Pediatric nurse triage. Its efficacy, safety, and implications for care.

This study evaluates emergency room (ER) triage at a large urban children's hospital, in which patients are routinely referred outside of the institution for care. Seven hundred forty-eight children from 1 week to 17 years of age were enrolled in the study over a six-week period. Nearly two thirds (61%) of the patients were sent outside of the hospital for care; 31% of the patients were sent to community health centers, 17% were sent to private physicians' offices, 13% were sent home (self-care), and only 9% were treated in the ER. Ninety-four percent of appointments--of which 74% were kept--were for care within two days of the triage visit, with patients who were sent to the ER or hospital clinics keeping more appointments than those who were sent outside the hospital for care (97% vs 89% vs 62%). Patients who had an appointment on the same day kept it better than those who waited one to three days, who in turn had a higher rate of appointment-keeping than those who waited more than three days (81% vs 63.4% vs 41.2%). The physician's diagnosis agreed with the triage nurse's diagnosis or was less serious than the nurse's diagnosis in 93.4% of patients. At two weeks after triage, nearly all patients had completely recovered, with no correlation of symptoms with level or site of care. This study indicates that nurse triage of pediatric walk-in patients, in which three of five patients are referred outside of the hospital for care, is a safe and effective alternative to care in the ER and, at the same time, serves to reinforce community health centers as the appropriate setting for primary care.

The fidelity of template-directed oligonucleotide ligation and its relevance to DNA computation.

Several different computational problems have been solved using DNA as a medium. However, the DNA computations that have so far been carried out have examined a relatively small number of possible sequence solutions in order to find correct sequence solutions. We have encoded a search algorithm in DNA that required the evaluation of >16 000 000 possible sequence solutions in order to find a single, correct sequence solution. Experimental evaluation of the search algorithm revealed bounds for the accuracies of answers to other large, computationally complex problems and suggested methods for the optimization of DNA computations in general. Short oligonucleotide substrates performed substantially better than longer substrates. Large, computationally complex problems whose evaluation requires hybridization and ligation can likely best be encoded and evaluated using short oligonucleotides at mesophilic temperatures.

Yersinia pestis pFra shows biovar-specific differences and recent common ancestry with a Salmonella enterica serovar Typhi plasmid.

Population genetic studies suggest that Yersinia pestis, the cause of plague, is a clonal pathogen that has recently emerged from Yersinia pseudotuberculosis. Plasmid acquisition is likely to have been a key element in this evolutionary leap from an enteric to a flea-transmitted systemic pathogen. However, the origin of Y. pestis-specific plasmids remains obscure. We demonstrate specific plasmid rearrangements in different Y. pestis strains which distinguish Y. pestis bv. Orientalis strains from other biovars. We also present evidence for plasmid-associated DNA exchange between Y. pestis and the exclusively human pathogen Salmonella enterica serovar Typhi.

Complete DNA sequence of a serogroup A strain of Neisseria meningitidis Z2491.

Neisseria meningitidis causes bacterial meningitis and is therefore responsible for considerable morbidity and mortality in both the developed and the developing world. Meningococci are opportunistic pathogens that colonize the nasopharynges and oropharynges of asymptomatic carriers. For reasons that are still mostly unknown, they occasionally gain access to the blood, and subsequently to the cerebrospinal fluid, to cause septicaemia and meningitis. N. meningitidis strains are divided into a number of serogroups on the basis of the immunochemistry of their capsular polysaccharides; serogroup A strains are responsible for major epidemics and pandemics of meningococcal disease, and therefore most of the morbidity and mortality associated with this disease. Here we have determined the complete genome sequence of a serogroup A strain of Neisseria meningitidis, Z2491. The sequence is 2,184,406 base pairs in length, with an overall G+C content of 51.8%, and contains 2,121 predicted coding sequences. The most notable feature of the genome is the presence of many hundreds of repetitive elements, ranging from short repeats, positioned either singly or in large multiple arrays, to insertion sequences and gene duplications of one kilobase or more. Many of these repeats appear to be involved in genome fluidity and antigenic variation in this important human pathogen.