Diagnostic Clinical and Laboratory Findings in Response to Predetermining Bacterial Pathogen: Data from the Meningitis Registry

Background

Childhood Meningitis continues to be an important cause of mortality in many countries. The search for rapid diagnosis of acute bacterial meningitis has lead to the further exploration of prognostic factors. This study was scheduled in an attempt to analyze various clinical symptoms as well as rapid laboratory results and provide an algorithm for the prediction of specific bacterial aetiology of childhood bacterial meningitis.

Methodology and Principal Findings

During the 32 year period, 2477 cases of probable bacterial meningitis (BM) were collected from the Meningitis Registry (MR). Analysis was performed on a total of 1331 confirmed bacterial meningitis cases of patients aged 1 month to 14 years. Data was analysed using EPI INFO (version 3.4.3-CDC-Atlanta) and SPSS (version 15.0 - Chicago) software. Statistically significant (p<0.05) variables were included in a conditional backward logistic regression model. A total of 838 (63.0%) attributed to Neisseria meningitidis, 252 (18.9%) to Haemophilus influenzae, 186 (14.0%) to Streptococcus pneumoniae and 55 (4.1%) due to other bacteria. For the diagnosis of Meningococcal Meningitis, the most significant group of diagnostic criteria identified included haemorrhagic rash (OR 22.36), absence of seizures (OR 2.51), headache (OR 1.83) and negative gram stain result (OR 1.55) with a Positive Predictive Value (PPV) of 96.4% (95%CI 87.7–99.6). For the diagnosis of Streptococcus pneumoniae, the most significant group of diagnostic criteria identified included absence of haemorrhagic rash (OR 13.62), positive gram stain (OR 2.10), coma (OR 3.11), seizures (OR 3.81) and peripheral WBC≥15000/µL (OR 2.19) with a PPV of 77.8% (95%CI 40.0–97.2). For the diagnosis of Haemophilus influenzae, the most significant group of diagnostic criteria included, absence of haemorrhagic rash (OR 13.61), age≥1year (OR 2.04), absence of headache (OR 3.01), CSF Glu<40 mg/dL (OR 3.62) and peripheral WBC<15000/µL (OR 1.74) with a PPV of 58.5% (95%CI 42.1–73.7).

Conclusions

The use of clinical and laboratory predictors for the assessment of the causative bacterial pathogen rather than just for predicting outcome of mortality seems to be a useful tool in the clinical management and specific treatment of BM. These findings should be further explored and studied.     

A Novel Immunological Assay for Hepcidin Quantification in Human Serum

Background

Hepcidin is a 25-aminoacid cysteine-rich iron regulating peptide. Increased hepcidin concentrations lead to iron sequestration in macrophages, contributing to the pathogenesis of anaemia of chronic disease whereas decreased hepcidin is observed in iron deficiency and primary iron overload diseases such as hereditary hemochromatosis. Hepcidin quantification in human blood or urine may provide further insights for the pathogenesis of disorders of iron homeostasis and might prove a valuable tool for clinicians for the differential diagnosis of anaemia. This study describes a specific and non-operator demanding immunoassay for hepcidin quantification in human sera.

Methods and Findings

An ELISA assay was developed for measuring hepcidin serum concentration using a recombinant hepcidin25-His peptide and a polyclonal antibody against this peptide, which was able to identify native hepcidin. The ELISA assay had a detection range of 10–1500 µg/L and a detection limit of 5.4 µg/L. The intra- and interassay coefficients of variance ranged from 8–15% and 5–16%, respectively. Mean linearity and recovery were 101% and 107%, respectively. Mean hepcidin levels were significantly lower in 7 patients with juvenile hemochromatosis (12.8 µg/L) and 10 patients with iron deficiency anemia (15.7 µg/L) and higher in 7 patients with Hodgkin lymphoma (116.7 µg/L) compared to 32 age-matched healthy controls (42.7 µg/L).

Conclusions

We describe a new simple ELISA assay for measuring hepcidin in human serum with sufficient accuracy and reproducibility.     

Agonist versus antagonist muscle fatigue effects on thigh muscle activity and vertical ground reaction during drop landing

BackgroundAgonist and antagonist co-activation plays an important role for stabilizing the knee joint, especially after fatigue. However, whether selective fatigue of agonists or antagonist muscles would cause different changes in muscle activation patterns is unknown.HypothesisKnee extension fatigue would have a higher influence on landing biomechanics compared with a knee flexion protocol.Study designRepeated-measures design.MethodsTwenty healthy subjects (10 males and 10 females) performed two sets of repeated maximal isokinetic concentric efforts of the knee extensors (KE) at 120° s^?1 until they could no longer consistently produce 30% of maximum torque. On a separate day, a similar knee flexion (KF) fatigue protocol was also performed. Single leg landings from 30 cm drop height were performed before, in the middle and after the end of the fatigue test. The mean normalized electromyographic (EMG) signal of the vastus medialis (VM), vastus lateralis (VL), biceps femoris (BF) and gastrocnemius (GAS) at selected landing phases were determined before, during and after fatigue. Quadriceps:hamstrings (Q:H) EMG ratio as well as sagittal hip and knee angles and vertical ground reaction force (GRF) were also recorded.ResultsTwo-way analysis of variance designs showed that KE fatigue resulted in significantly lower GRF and higher knee flexion angles at initial contact while maximum hip and knee flexion also increased (p < 0.05). This was accompanied by a significant decline of BF EMG, unaltered EMG of vastii and GAS muscles and increased Q:H ratio. In contrast, KF fatigue had no effects on vGRFs but it was accompanied by increased activation of VM, BF and GAS while the Q:H increased during before landing and decreased after impact.ConclusionFatigue responses during landing are highly dependent on the muscle which is fatigued.     

Integrated single‐cell analysis shows Pichia pastoris secretes protein stochastically

The production of heterologous proteins by secretion from cellular hosts is an important determinant for the cost of biotherapeutics. A single‐cell analytical method called microengraving was used to examine the heterogeneity in secretion by the methylotrophic yeast Pichia pastoris. We show that constitutive secretion of a human Fc fragment by P. pastoris is not cell‐cycle dependent, but rather fluctuates between states of high and low productivity in a stochastic manner. Biotechnol. Bioeng. 2010;106: 319–325. © 2010 Wiley Periodicals, Inc.     

Reducing power and radical scavenging activity of four Parmeliaceae species

The methanol extracts of four Parmeliaceae lichens (Hypogymnia physodes, Evernia prunastri, Flavoparmelia caperata and Parmelia sulcata) were screened for antioxidant properties and total phenol content. The H. physodes extract was the most effective at reducing iron(III) and scavenging 1,1-diphenyl-2-picrylhydrazyl radicals, while the P. sulcata extract was the most effective in reducing molybdenum(VI) in an acidic medium. The E. prunastri and H. physodes extracts contained more Folin-Ciocalteu reagent reactive substances than the F. caperata and P. sulcata extracts. Significant activity of the H. physodes extract in DPPH and reducing Fe(III) assays suggest that this lichen can be considered as a potential source of antioxidants.     

Electron transfer to photosystem 1 from spinach plastocyanin mutated in the small acidic patch: ionic strength dependence of kinetics and comparison of mechanistic models

A set of plastocyanin (Pc) mutants, probing the small acidic patch (Glu59, Glu60, and Asp61) and a nearby residue, Gln88, has been constructed to provide further insight into the electron transfer process between Pc and photosystem 1. The negatively charged residues were changed into their neutral counterparts or to a positive lysine. All mutant proteins exhibited electron transfer kinetics qualitatively similar to those of the wild type protein over a wide range of Pc concentrations. The kinetics were slightly faster for the Gln88Lys mutant, while they were significantly slower for the Glu59Lys mutant. The data were analyzed with two different models: one involving a conformational change of the Pc-photosystem 1 complex that precedes the electron transfer step (assumed to be irreversible) [Bottin, H., and Mathis, P. (1985) Biochemistry 24, 6453-6460] and another where no conformational change occurs, the electron transfer step is reversible, and dissociation of products is explicitly taken into account [Drepper, F., Hippler, M., Nitschke, W., and Haehnel, W. (1996) Biochemistry 35, 1282-1295]. Both models can account for the observed kinetics in the limits of low and high Pc concentrations. To discriminate between the models, the effects of added magnesium ions on the kinetics were investigated. At a high Pc concentration (0.7 mM), the ionic strength dependence was found to be consistent with the model involving a conformational change but not with the model where the electron transfer is reversible. One residue in the small acidic patch, Glu60, seems to be responsible for the major part of the ionic strength dependence of the kinetics.     

Newly isolated bacterial strains belonging to Bacillaceae (Bacillus sp.) and Micrococcaceae accelerate death of the honey bee mite, Varroa destructor (V. jacobsoni), in laboratory assays

Newly isolated bacterial strains belonging to Bacillaceae (Bacillus sp.), Micrococcaceae and three unidentified strains were tested for their pathogenicity against the mite, Varroa destructor. The Bacillus sp. strain and two of the strains belonging to the Micrococcaceae family significantly decreased the time for 50% mortality of the mite population (up to 57%) and hence may be potential control agents. In in vitro bioassay whole cells, extracellular broth and cellular extract of the Bacillus sp. strain effectively killed the mites, suggesting that both endotoxins and exotoxins contributed to the killing.     

Organ-specific cell division abnormalities caused by mutation in a general cell cycle regulator in C. elegans

The precise control of cell division during development is pivotal for morphogenesis and the correct formation of tissues and organs. One important gene family involved in such control is the p21/p27/p57 class of negative cell cycle regulators. Loss of function of the C. elegans p27 homolog, cki-1, causes extra cell divisions in numerous tissues including the hypodermis, the vulva, and the intestine. We have sought to better understand how cell divisions are controlled upstream or in parallel to cki-1 in specific organs during C. elegans development. By taking advantage of the invariant cell lineage of C. elegans, we used an intestinal-specific GFP reporter in a screen to identify mutants that undergo cell division abnormalities in the intestinal lineage. We have isolated a mutant with twice the wild-type complement of intestinal cells, all of which arise during mid-embryogenesis. This mutant, called rr31, is a fully dominant, maternal-effect, gain-of-function mutation in the cdc-25.1 cell cycle phosphatase that sensitizes the intestinal lineage to an extra cell division. We showed that cdc-25.1 acts at the G1/S transition, as ectopic expression of CDC-25.1 caused entry into S phase in intestinal cells. In addition, we showed that the cdc-25.1(gf) requires cyclin E. The extra cell division defect was shown to be restricted to the E lineage and the E fate is necessary and sufficient to sensitize cells to this mutation.