'Khatatonia' - cathinone-induced hypertensive encephalopathy.

Khat consumption is an under-recognised cause of hypertensive encephalopathy and intraparenchymal brain haemorrhage. We report the radiological findings of extensive periventricular, subcortical and brain stem white matter pathology of a patient who had consumed excessive amounts of Khat. The Khat plant contains cathinone, an amphetamine-like alkaloid which has been associated with chronic hypertensive end-organ damage, but is seldom considered a cause of cerebrovascular events in northern Europe.

spa Typing and Multilocus Sequence Typing Show Comparable Performance in a Macroepidemiologic Study of Staphylococcus aureus in the United States.

A number of molecular typing methods have been developed for characterization of Staphylococcus aureus isolates. The utility of these systems depends on the nature of the investigation for which they are used. We compared two commonly used methods of molecular typing, multilocus sequence typing (MLST) (and its clustering algorithm, Based Upon Related Sequence Type [BURST]) with the staphylococcal protein A (spa) typing (and its clustering algorithm, Based Upon Repeat Pattern [BURP]), to assess the utility of these methods for macroepidemiology and evolutionary studies of S. aureus in the United States. We typed a total of 366 clinical isolates of S. aureus by these methods and evaluated indices of diversity and concordance values. Our results show that, when combined with the BURP clustering algorithm to delineate clonal lineages, spa typing produces results that are highly comparable with those produced by MLST/BURST. Therefore, spa typing is appropriate for use in macroepidemiology and evolutionary studies and, given its lower implementation cost, this method appears to be more efficient. The findings are robust and are consistent across different settings, patient ages, and specimen sources. Our results also support a model in which the methicillin-resistant S. aureus (MRSA) population in the United States comprises two major lineages (USA300 and USA100), which each consist of closely related variants.

Molecular characterization of Staphylococcus aureus in the United States 2004-2008 reveals the rapid expansion of USA300 among inpatients and outpatients.

To assess the clonal structure of Staphylococcus aureus in the United States, we performed a molecular epidemiological study of 1,055 S. aureus isolates from a nationally representative clinical isolate collection from 2004-2008. Resistant and susceptible isolates were typed with multilocus sequence typing, tested for the presence of Panton-Valentine leukocidin (PVL), and serotyped. USA300 (multilocus sequence typing clonal complex 8, PVL positive, and methicillin-resistant) was the most frequently isolated clone, expanding from 12% of all isolates in 2004 to 38% in 2006. The USA300 clone increased significantly in frequency among both outpatients and inpatients. USA300 increased in both skin and soft-tissue and invasive infection isolates. The second most frequently observed clone was clonal complex 5, PVL-negative, and methicillin-resistant, and its frequency was stable from 2004-2008. The methicillin-susceptible S. aureus in the study was polyclonal, and decreased in frequency as it was replaced by USA300.

Prevalence and sequence variation of panton-valentine leukocidin in methicillin-resistant and methicillin-susceptible staphylococcus aureus strains in the United States.

Panton-Valentine leukocidin (PVL), encoded by the lukSF-PV genes, is a putative virulence factor and marker for community-associated methicillin-resistant Staphylococcus aureus. Here we report the prevalence of PVL among a representative sample of 1,055 S. aureus infection isolates from the United States and describe the sequence variation of the lukSF-PV genes. We performed multilocus sequence typing (MLST) on all isolates and sequenced fragments of the lukSF-PV genes from a sample of 86 isolates. We assigned isolates to a PVL R or H sequence type based on a polymorphism that results in an amino acid change from arginine (R) to histidine (H). Overall, we found that 36% of S. aureus isolates were positive for lukSF-PV. Among the 86 we typed, we identified 72 R variants and 14 H variants. Among the 47 methicillin-resistance S. aureus (MRSA) isolates, 43 harbored the R variant, and among the 39 methicillin-susceptible S. aureus (MSSA) isolates, 29 harbored the R variant. Almost all (97%) of the R variants were found in MLST clonal complex 8 (CC8), while the H variant was broadly distributed among 6 CCs. Within CC8, all 38 MRSA (USA300) and all 28 MSSA isolates harbored the R variant. Of the 20 isolates from blood and the lower respiratory tract, 19 (95%) harbored the R variant. While the R variant had been linked primarily to USA300 MRSA, we found that all CC8 MSSA isolates also contained the R variant, suggesting that some strains of USA300 may have lost methicillin resistance as an adaptation in the community.

Behavioral and spermatogenic hybrid male breakdown in Nasonia.

Several reproductive barriers exist within the Nasonia species complex, including allopatry, premating behavioral isolation, postzygotic inviability and Wolbachia-induced cytoplasmic incompatibility. Here we show that hybrid males suffer two additional reproductive disadvantages, an inability to properly court females and decreased sperm production. Hybrid behavioral sterility, characterized by a reduced ability of hybrids to perform necessary courtship behaviors, occurs in hybrids between two species of Nasonia. Hybrid males produced in crosses between N. vitripennis and N. giraulti courted females at a reduced frequency (23-69%), compared with wild-type N. vitripennis and N. giraulti males (>93%). Reduced courtship frequency was not a simple function of inactivity among hybrids. A strong effect of cytoplasmic (mitochondrial) background was also found in N. vitripennis and N. giraulti crosses; F2 hybrids with giraulti cytoplasm showing reduced ability at most stages of courtship. Hybrids produced between a younger species pair, N. giraulti and N. longicornis, were behaviorally fertile. All males possessed motile sperm, but sperm production is greatly reduced in hybrids between the older species pair, N. vitripennis and N. giraulti. This effect on hybrid males, lowered sperm counts rather than nonfunctional sperm, is different from most described cases of hybrid male sterility, and may represent an earlier stage of hybrid sperm breakdown. The results add to previous studies of F2 hybrid inviability and behavioral sterility, and indicate that Wolbachia-induced hybrid incompatibility has arisen early in species divergence, relative to behavioral sterility and spermatogenic infertility.

Molecular epidemiology of methicillin-resistant and methicillin-susceptible Staphylococcus aureus isolates from global clinical trials.

Determining the genetic characteristics of Staphylococcus aureus is important for better understanding of the global and dynamic epidemiology of this organism as we witness the emergence and spread of virulent and antibiotic-resistant clones. We genotyped 292 S. aureus isolates (105 methicillin resistant and 187 methicillin susceptible) using a combination of pulsed-field gel electrophoresis, multilocus sequence typing, and SCCmec typing. In addition, S. aureus isolates were tested for the presence of the Panton-Valentine leukocidin (PVL) genes. Isolates were recovered from patients with uncomplicated skin infections in 10 different countries during five phase III global clinical trials of retapamulin, a new topical antibiotic agent. The most common methicillin-resistant clone had multilocus sequence type 8, pulsed-field type USA300, and SCCmec type IV and possessed the PVL genes. This clone was isolated exclusively in the United States. The most common PVL-positive, methicillin-susceptible clone had multilocus sequence type 121 and pulsed-field type USA1200. This clone was found primarily in South Africa and the Russian Federation. Other clones were found at lower frequencies and were limited in their geographic distribution. Overall, considerable genetic diversity was observed within multilocus sequence type clonal complexes and pulsed-field types.

Temporal and spatial distribution of clonal complexes of Streptococcus pneumoniae isolates resistant to multiple classes of antibiotics in Belgium, 1997 to 2004.

We performed multilocus sequence typing on 203 invasive disease isolates of Streptococcus pneumoniae to assess the clonal compositions of isolates from two provinces in Belgium and to determine the relationship between clones and antibiotic nonsusceptibility, particularly nonsusceptibility to two or more classes of antibiotics. The frequency of multiclass nonsusceptibility (MCNS) was higher in the province of West Flanders (38%) than in Limburg (21%). This difference was largely attributable to five clonal complexes (CC156, CC81, CC143, CC193, and CC1848), which contained high proportions of isolates with MCNS (>47%) and which were circulating at higher frequencies in West Flanders. The S. pneumoniae population changed over time, as CC156 and CC81 declined in frequency from 1997 to 1999 to 2001 to 2004. Over the same time period, the frequency of pneumococcal conjugate vaccine 7 (PCV7) serotypes dropped from 69% to 41%. In contrast, the nonvaccine serotype 19A increased in frequency from 2.1% to 6.6%. None of these changes can be attributed to PCV7 vaccine, as it was not in use in Belgium during the time period studied. There was evidence that MCNS clones flowed from West Flanders to Limburg.

A geographic variant of the Staphylococcus aureus Panton-Valentine leukocidin toxin and the origin of community-associated methicillin-resistant S. aureus USA300.

BACKGROUND: The majority of recent community-associated methicillin-resistant Staphylococcus aureus (MRSA) infections in the United States have been caused by a single clone, USA300. USA300 secretes Panton-Valentine leukocidin (PVL) toxin, which is associated with highly virulent infections. METHODS: We sequenced the PVL genes of 174 S. aureus isolates from a global clinical sample. We combined phylogenetic reconstruction and protein modeling methods to analyze genetic variation in PVL. RESULTS: Nucleotide variation was detected at 12 of 1726 sites. Two PVL sequence variants, the R variant and the H variant, were identified on the basis of a substitution at nt 527. Of sequences obtained in the United States, 96.7% harbor the R variant, whereas 95.6% of sequences obtained outside the United States harbor the H variant; 91.3% of MRSA isolates harbor the R variant, and 91.3% of methicillin-susceptible strains harbor the H variant. A molecular model of PVL shows 3 mechanisms by which the amino acid substitution may affect PVL function. CONCLUSIONS: All sampled PVL genes appear to share a recent common ancestor and spread via a combination of clonal expansion and horizontal transfer. US isolates harbor a variant of PVL that is strongly associated with MRSA infections. Protein modeling reveals that this variant may have functional significance. We propose a hypothesis for the origin of USA300.

Zebrafish Lmx1b.1 and Lmx1b.2 are required for maintenance of the isthmic organizer.

The mesencephalic and metencephalic region (MMR) of the vertebrate central nervous system develops in response to signals produced by the isthmic organizer (IsO). We have previously reported that the LIM homeobox transcription factor Lmx1b is expressed within the chick IsO, where it is sufficient to maintain expression of the secreted factor wnt1. In this paper, we show that zebrafish express two Lmx1b orthologs, lmx1b.1 and lmx1b.2, in the rostral IsO, and demonstrate that these genes are necessary for key aspects of MMR development. Simultaneous knockdown of Lmx1b.1 and Lmx1b.2 using morpholino antisense oligos results in a loss of wnt1, wnt3a, wnt10b, pax8 and fgf8 expression at the IsO, leading ultimately to programmed cell death and the loss of the isthmic constriction and cerebellum. Single morpholino knockdown of either Lmx1b.1 or Lmx1b.2 has no discernible effect on MMR development. Maintenance of lmx1b.1 and lmx1b.2 expression at the isthmus requires the function of no isthmus/pax2.1, as well as Fgf signaling. Transient misexpression of Lmx1b.1 or Lmx1b.2 during early MMR development induces ectopic wnt1 and fgf8 expression in the MMR, as well as throughout much of the embryo. We propose that Lmx1b.1- and Lmx1b.2-mediated regulation of wnt1, wnt3a, wnt10b, pax8 and fgf8 maintains cell survival in the isthmocerebellar region.

Wolbachia-induced incompatibility precedes other hybrid incompatibilities in Nasonia.

Wolbachia are cytoplasmically inherited bacteria that cause a number of reproductive alterations in insects, including cytoplasmic incompatibility, an incompatibility between sperm and egg that results in loss of sperm chromosomes following fertilization. Wolbachia are estimated to infect 15-20% of all insect species, and also are common in arachnids, isopods and nematodes. Therefore, Wolbachia-induced cytoplasmic incompatibility could be an important factor promoting rapid speciation in invertebrates, although this contention is controversial. Here we show that high levels of bidirectional cytoplasmic incompatibility between two closely related species of insects (the parasitic wasps Nasonia giraulti and Nasonia longicornis) preceded the evolution of other postmating reproductive barriers. The presence of Wolbachia severely reduces the frequency of hybrid offspring in interspecies crosses. However, antibiotic curing of the insects results in production of hybrids. Furthermore, F1 and F2 hybrids are completely viable and fertile, indicating the absence of F1 and F2 hybrid breakdown. Partial interspecific sexual isolation occurs, yet it is asymmetric and incomplete. Our results indicate that Wolbachia-induced reproductive isolation occurred in the early stages of speciation in this system, before the evolution of other postmating isolating mechanisms (for example, hybrid inviability and hybrid sterility).

A community based approach to bicycle helmet use counts.

OBJECTIVE: Bicycle helmet use has become an important measure of the effectiveness of bicycle safety programs and the effectiveness of helmet legislation. Accounts of analytical comparisons of observation site selection methods are scarce. This report addresses this gap by reporting the relative effectiveness and costs of two alternative approaches to the selection of observation sites for helmet use counts. METHODS: The community based (COBA) method of site selection entailed asking community informants to identify locations frequented by young bicycle riders. In the bicycle club/map (CLMA) method, site selections were based on recommendations from club members of sites at which cyclists were likely to be found and through examination of maps, keying on local features. These alternative site selection methods were compared in terms of their overall and cost effectiveness in locating youth riders. RESULTS: Despite fewer observer hours and fewer sites in a sparsely populated rural county, the COBA method yielded greater numbers of riding youth and from 1.9 to 4.6 times more youth riders per observer hour than did the CLMA method in two densely populated suburban counties. In addition, costs per youth rider observed associated with the COBA method were 2.9 to 7.0 times lower than those associated with the CLMA method. CONCLUSIONS: Community based site identification is both more efficient in locating youth riders and more cost effective.

Serum cholesterol and triglycerides in relation to ponderal index and age in two contrasting populations.

One hundred and seventy six mentally retarded adult patients had their serum cholesterol, triglycerides and ponderal index determined during a seven week period and compared with those of a normal group of business executives being routinely screened by the same laboratory. A comparison of cholesterol and triglyceride levels showed those of the former group to be significantly lower, as dealt with in a previous paper by Lawlor, O'Hara and Birtwistle (1974). The values in mentally subnormal males showed no correlations with ponderal index, whereas the normal males showed highly significant correlations throughout. Both the normal and subnormal females showed highly significant correlations of cholesterol with triglyceride levels, and of age with cholesterol concentration, but not of ponderal index with either cholesterol or triglyceride levels.