Series of incidents of Listeria monocytogenes non-invasive febrile gastroenteritis involving ready-to-eat meats

AIMS: A series of cases and outbreaks of febrile noninvasive gastrointestinal disease involving 31 identified cases was investigated in terms of the numbers and types of Listeria monocytogenes present in the suspect foods (ready-to-eat meats) and clinical samples from cases. METHODS AND RESULTS: Foods and faecal samples involved in the incidents were tested for the presence and number of L. monocytogenes. Isolates were typed by macrorestriction analysis using pulsed-field gel electrophoresis. The foods contained high levels of L. monocytogenes, in one case 1.8 x 10(7) g-1. Faecal samples contained L. monocytogenes for up to 15 d after the contaminated food was consumed. All isolates from the food and faecal samples were of serotype 1/2 and were indistinguishable from one another by macrorestriction typing. CONCLUSIONS: It is likely that the meats were contaminated either during their manufacture after they had been cooked or by underprocessing. The long shelf lives on these products would have allowed the contaminating L. monocytogenes to grow to the high numbers measured in this study, causing food poisoning as described. SIGNIFICANCE AND IMPACT OF THE STUDY: Outbreaks of febrile noninvasive listeriosis are relatively rare. This report adds ready-to-eat meats to the range of foods that have acted as vehicles for such outbreaks.     

The complex nature of protein phosphatases

Protein phosphatases are integrally associated with the regulation of cellular signaling. The mechanisms underlying the specific regulatory roles are likely to be unique to each cell system. Nevertheless, analysis of phosphatase regulation in a number of systems has identified phosphatase targeting through association with a wide range of binding partners to be a fundamental mechanism of regulation. Using protein phosphatase 2A (PP2A) as an example, this snapshot summarizes these fundamental mechanisms of protein phosphatase regulation.     

Isotonic biaxial loading of fibroblast-populated collagen gels: a versatile, low-cost system for the study of mechanobiology

 We developed a simple, versatile system for applying a range of biaxial loads to cell–matrix constructs for the study of mechanobiology. The system consists of porous polyethylene bars that are polymerized into a square fibroblast-populated gel and loaded by freely hanging weights attached to sutures routed through a custom loading rig. The cost to manufacture each mold/loading rig pair was less than US $250 and the expected life of the components is up to 10 years. Neonatal and adult cardiac fibroblasts contracted gels to a decreasing extent as external load was increased (P=0.003) and achieved contraction forces of up to 1.4 mN per million cells. Strain distributions were reasonably homogeneous in the central region of the gel (25% of gel area), but clearly nonhomogeneous outside that central region. The primary advantages of this system are simplicity, low cost, biaxial loading, and the ability to test for a dose–response effect of mechanical load. The current disadvantages are the inability to apply cycling loading and the inhomogeneities introduced by the use of rigid loading bars. Received: 15 November 2001 / Accepted: 30 January 2002     

A multiplex polymerase chain reaction for a differential diagnosis of Plasmodium falciparum and Plasmodium vivax

A multiplex PCR was designed for the differential diagnosis of the two parasite species by targeting the 18S rRNA gene with a set of primer combinations, amplifying DNA fragments of 1451-bp and 833-bp for P. falciparum and P. vivax, respectively. The sensitivity of this PCR test was high, as minimal as 0.1 parasite per one microliter of blood sample and a minimum of four copies of the target gene could be detected. For the diagnosis of mixed infection of two Plasmodium spp., there were no apparent competition or cross-reaction between the majority and minority Plasmodium species. The multiplex PCR was evaluated on 210 clinical samples and 60 normal controls. The PCR test yielded highly concordant results with microscopic examination, with the only one exception of a mixed (P. falciparum plus P. vivax) infection case, which was diagnosed as a single infection of P. falciparum by microscopy. We propose that the multiplex PCR is a sensitive, specific, and rapid tool that can serve as a useful differential diagnostic tool for detecting P. falciparum and P. vivax.     

Conodurine,conoduramine, and ervahanine derivatives from Tabernaemontana corymbosa

Four bisindole alkaloids, viz., 19'(S)-hydroxyconodurine, conodurinine, 19'(S)-hydroxyconoduramine, and 19'(S)-hydroxyervahanine A, in addition to conodurine and ervahanine A, were obtained from the leaf and stem-bark extracts of Tabernaemontana corymbosa. The structures of the new alkaloids were determined using NMR and MS analysis.     

Construction of a BAC library and generation of BAC end sequence-tagged connectors for genome sequencing of the African malaria mosquito Anopheles gambiae

A Bacterial Artificial Chromosome (BAC) genomic DNA library of Anopheles gambiae, the major human malaria vector in sub-Saharan Africa, was constructed and characterized. This library (ND-TAM) is composed of 30,720 BAC clones in eighty 384-well plates. The estimated average insert size of the library is 133 kb, with an overall genome coverage of approximately 14-fold. The ends of approximately two-thirds of the clones in the library were sequenced, yielding 32,340 pair-mate ends. A statistical analysis (G-test) of the results of PCR screening of the library indicated a random distribution of BACs in the genome, although one gap encompassing the white locus on the X-chromosome was identified. Furthermore, combined with another previously constructed BAC library (ND-1), ~2,000 BACs have been physically mapped by polytene chromosomal in situ hybridization. These BAC end pair mates and physically mapped BACs have been useful for both the assembly of a fully sequenced A. gambiae genome and for linking the assembled sequence to the three polytene chromosomes. This ND-TAM library is now publicly available at both http://www.malaria.mr4.org/mr4pages/index.html/ and http://hbz.tamu.edu/, providing a valuable resource to the mosquito research community.     

Studies on the behaviour of Pseudomonas fluorescens biofilms after Ortho-phthalaldehyde treatment

A relatively novel biocide, ortho-phthalaldehyde (OPA), was tested to control biofilms formed by Pseudomonas fluorescens on stainless steel surfaces. The toxic action of OPA was assessed in terms of inactivation and removal of the biofilm by means of, respectively, the determination of the respiratory activity and the variation in the dry weight of the biofilms. For comparison, the activity of OPA against suspended bacteria was also evaluated. The results showed that higher concentrations of OPA and longer exposure times are needed to inactivate P. fluorescens biofilms than planktonic populations, thus denoting that sessile bacteria have a reduced susceptibility to OPA. This appears to be associated with the reaction with the proteins of the matrix, as demonstrated by the reduction of the antimicrobial action of OPA in the presence of a protein (bovine serum albumin). The application of OPA appeared to cause little effect in the removal of biofilms from the metal slides since the mass of biofilm that remained on the surfaces, after biocide treatment, was within the same range as those observed in the control tests. These results suggest that, with OPA application, biofilms can be inactivated but stay attached to the surfaces, decreasing thereby the success of the chemical treatment.     

Enantioseparation of chiral alcohols by complex formation and subsequent supercritical fluid extraction

The very first application of supercritical fluid extraction (SFE) on enantioseparation of alcohols is discussed. Resolution of three chiral alcohols (trans-2-chloro-cyclohexanol, trans-2-bromo-cyclohexanol, and trans-2-iodo-cyclohexanol) were performed by partial complexation with (-)-O,O'-dibenzoyl-(2R,3R)-tartaric acid monohydrate (DBTA). DBTA formed diastereomeric complexes with all S,S-enantiomers stable enough to extract the unreacted alcohols with supercritical carbon dioxide. Resolution efficiency increased with the size of halogen substituents, and by the proper selection of molar ratio, pure (-)-R,R-trans-2-iodo-cyclohexanol (ee > 99%, yield: 39%) or (+)-S,S-trans-2-iodo-cyclohexanol (ee = 98%, yield: 8%) were prepared in one process step. Achieved resolution efficiency values were much higher in all resolution procedures than in any other known enantioseparation of these racemic compounds. The developed method offers an environmentally friendly, efficient alternative of currently applied resolution processes, also on a preparative scale.