Development of a proof-of-concept microfluidic portable pathogen analysis system for water quality monitoring

Waterborne diseases cause millions of deaths worldwide, especially in developing communities. The monitoring and rapid detection of microbial pathogens in water is critical for public health protection. This study reports the development of a proof-of-concept portable pathogen analysis system (PPAS) that can detect bacteria in water with the potential application in a point-of-sample collection setting. A centrifugal microfluidic platform is adopted to integrate bacterial cell lysis in water samples, nucleic acid extraction, and reagent mixing with a droplet digital loop mediated isothermal amplification assay for bacteria quantification onto a single centrifugal disc (CD). Coupled with a portable "CD Driver" capable of automating the assay steps, the CD functions as a single step bacterial detection "lab" without the need to transfer samples from vial-to-vial as in a traditional laboratory. The prototype system can detect Enterococcus faecalis, a common fecal indicator bacterium, in water samples with a single touch of a start button within 1 h and having total hands-on-time being less than 5 min. An add-on bacterial concentration cup prefilled with absorbent polymer beads was designed to integrate with the pathogen CD to improve the downstream quantification sensitivity. All reagents and amplified products are contained within the single-use disc, reducing the opportunity of cross contamination of other samples by the amplification products. This proof-of-concept PPAS lays the foundation for field testing devices in areas needing more accessible water quality monitoring tools and are at higher risk for being exposed to contaminated waters.

Variation in Galr1 expression determines susceptibility to exocitotoxin-induced cell death in mice

Inbred strains of mice differ in their susceptibility to excitotoxin-induced cell death, but the genetic basis of individual variation in differential susceptibility is unknown. Previously, we identified a highly significant quantitative trait locus (QTL) on chromosome 18 that influenced susceptibility to kainic acid-induced cell death (Sicd1). Comparison of susceptibility to seizure-induced cell death between reciprocal congenic lines for Sicd1 and parental background mice indicates that genes influencing this trait were captured in both strains. Two positional gene candidates, Galr1 and Mbp, map to 55 cM, where the Sicd1 QTL had been previously mapped. Thus, this study was undertaken to determine if Galr1 and/or Mbp could be considered as candidate genes. Genomic sequence comparison of these two functional candidate genes from the C57BL/6J (resistant at Sicd1) and the FVB/NJ (susceptible at Sicd1) strains showed no single-nucleotide polymorphisms. However, expression studies confirmed that Galr1 shows significant differential expression in the congenic and parental inbred strains. Galr1 expression was downregulated in the hippocampus of C57BL/6J mice and FVB.B6-Sicd1 congenic mice when compared with FVB/NJ or B6.FVB-Sicd1 congenic mice. A survey of Galr1 expression among other inbred strains showed a significant effect such that 'susceptible' strains showed a reduction in Galr1 expression as compared with 'resistant' strains. In contrast, no differences in Mbp expression were observed. In summary, these results suggest that differential expression of Galr1 may contribute to the differences in susceptibility to seizure-induced cell death between cell death-resistant and cell death-susceptible strains.

Effect of age on kainate-induced seizure severity and cell death

While the onset and extent of epilepsy increases in the aged population, the reasons for this increased incidence remain unexplored. The present study used two inbred strains of mice (C57BL/6J and FVB/NJ) to address the genetic control of age-dependent neurodegeneration by building upon previous experiments that have identified phenotypic differences in susceptibility to hippocampal seizure-induced cell death. We determined if seizure induction and seizure-induced cell death are affected differentially in young adult, mature, and aged male C57BL/6J and FVB/NJ mice administered the excitotoxin, kainic acid. Dose response testing was performed in three to four groups of male mice from each strain. Following kainate injections, mice were scored for seizure activity and brains from mice in each age group were processed for light microscopic histopathologic evaluation 7 days following kainate administration to evaluate the severity of seizure-induced brain damage. Irrespective of the dose of kainate administered or the age group examined, resistant strains of mice (C57BL/6J) continued to be resistant to seizure-induced cell death. In contrast, aged animals of the FVB/NJ strain were more vulnerable to the induction of behavioral seizures and associated neuropathology after systemic injection of kainic acid than young or middle-aged mice. Results from these studies suggest that the age-related increased susceptibility to the neurotoxic effects of seizure induction and seizure-induced injury is regulated in a strain-dependent manner, similar to previous observations in young adult mice.

First Report of Horse Chestnut Powdery Mildew Caused by Erysiphe flexuosa in Castilla y León, Spain

Horse chestnut (Aesculus hippocastanum L.) is an important ornamental tree in many gardens in Castilla y León (northern Spain). During the summer and autumn of 2005 and 2006, disease signs resembling powdery mildew were observed in Condesa de Sagasta Boulevard and Quevedo Botanical Garden in León. Whitish fungal growth was visible macroscopically on the upper and lower leaf surfaces of both young and old leaves and petioles. The disease reduced tree attractiveness and could cause important aesthetic damage in the parks. Five symptomatic trees older than 30 years were observed in each park, and 10 leaves per tree were collected. Microscopic examinations of the leaf surfaces revealed ectophytic, hyaline hyphae with lobed appresoria, solitary or in pairs. Conidia were barrel to broadly subglobose and ranged from 23 to 37 μm long and 8 to 16 μm wide. They were produced singly on two- or three-celled conidiophores. Chasmothecia were produced in abundance, mostly on the lower leaf surface. They were globose, 120 to 160 μm in diameter, dark brown, and bore two types of appendages; long and flexuous with simple hook-like apices or short, simple, tapered, and rough walled. The long appendages measured 87 to 182 μm and the shorter ones measured 12 to 32 μm. Chasmothecia contained three to five asci, each developing six to eight hyaline, round, and single-celled ascospores when matured. Pathogenicity was confirmed on Aesculus sp. branches by healthy leaves being inoculated by touching them with powdery mildew-infected leaves. Noninoculated leaves served as controls. The appearance of colonies in the infected leaves was observed 15 days after the inoculation, but not in the controls. The pathogen was identified as Erysiphe flexuosa (Peck) U. Braun & S. Takamatsu, a North American powdery mildew. It has been recently introduced in Europe (1) and is now present in a number of countries (2). To our knowledge, this is the first report of E. flexuosa in this region of Spain. References: (1) N. Ale-Agha et al. Cryptogam. Mycol. 21:89, 2000. (2) K. Zimmermannová-Pastirčáková et al. Schlechtendalia 8:39, 2002.

Establishment of a cytokine-producing anaplastic large-cell lymphoma cell line containing the t(2;5) translocation: potential role of cytokines in clinical manifestations

A permanent cell line, HSC-M1, was established from a child with advanced CD30 (Ki-1)+ anaplastic large-cell lymphoma (ALCL). Clinical features included irritability, fever, weight loss, tender lymphadenopathy, pneumonitis, neutrophilia, and bone marrow erythrophagocytosis. While HSC-M1 cells exhibited an immunophenotype characteristic of ALCL of T-cell lineage, the cell line also demonstrated features of monocyte-macrophage lineage. Cytogenetic and polymerase chain reaction (PCR) analysis of the HSC-M1 cell line and involved bone marrow demonstrated the characteristic non-random chromosomal translocation t(2:5)(p23:q35). Reverse transcriptase PCR for mRNA expression of cytokines and cytokine receptors showed that HSC-M1 cells expressed the message for multiple cytokines and their receptors. Measurement of cytokine levels in serum samples using enzyme-linked immunosorbent assays showed increased concentrations of several cytokines. The increased levels of some cytokines correlated with disease activity and clinical symptoms. Although spontaneous production by HSC-M1 cells of some of these cytokines was demonstrated, the production of others was only detectable after stimulation with exogenous CD30 ligand. With few exceptions, there was good correlation between serum cytokine levels and cytokines produced by HSC-M1 cells. These findings indicate that cytokine production is a feature of ALCL cells and that some of the clinical manifestations in ALCL may result from cytokines produced by either the malignant or accessory cells.

Constitutional balanced translocations in alveolar rhabdomyosarcoma

Chromosomal analysis of tumor tissue from two children with alveolar rhabdomyosarcoma revealed t(1;5)(q32;q31) and t(1;22)(q21;q11.2) in all metaphases examined, respectively. Peripheral blood lymphocytes carried the same cytogenetic abnormality as that of the tumor cells in both patients. Parental lymphocytes were karyotypically normal in the patient with t(1;22), indicating a de novo constitutional translocation, but t(1;5) was paternally inherited in the other patient. The presence of constitutional translocations in these two children might have contributed to the development of alveolar rhabdomyosarcoma.

Effect of tube feedings on the measurement of gastric intramucosal pH

OBJECTIVE

To determine the effect of enteral tube feedings on the measurement of gastric intramucosal pH.

DESIGN

Interventional study.

SETTING

Two intensive care units of a university-affiliated teaching hospital.

PATIENTS

Twenty hemodynamically stable patients undergoing mechanical ventilation, with a nasogastric tonometer in situ, in whom enteral feeding was initiated.

INTERVENTIONS

The baseline fasting gastric intramucosal pH and gastric fluid pH were determined in the study population. The patients then received enteral feedings for 2 hrs, after which the gastric intramucosal pH and gastric fluid pH measurements were repeated. The tube feedings were then withheld for 2 hrs. The data set was repeated 1 and 2 hrs after the feedings had been stopped. Finally, tube feedings were retarded and the data set was repeated after 4 hrs. All patients received a histamine-2 (H2)-receptor antagonist-blocking agent during the study. To investigate the possibility that a direct reaction between gastric fluid and enteral feedings may generate CO2, 30-mL aliquots of gastric fluid from an independent sample of 14 patients (seven receiving cimetidine) were mixed with 60 mL of enteral feeding in an airtight container; the PCO2 of the gastric fluid before and after adding enteral feeding was measured tonometrically.

MEASUREMENTS AND MAIN RESULTS

The mean +/- SD gastric intramucosal pH decreased from 7.40 +/- 0.08 to 7.33 +/- 0.12 (p < .005), and from 7.38 +/- 0.07 to 7.31 +/- 0.1 (p < .005) after the first and second feeding challenges, respectively. The gastric intramucosal pH returned to the baseline value after 1 hr of fasting. The mean in vitro PCO2 of the gastric fluid increased from 11.9 +/- 3.0 to 16.2 +/- 2.0 torr (1.6 +/- 0.4 to 2.1 +/- 0.27 kPa) (p = .003) after the addition of tube feedings in the samples from those patients who were not receiving H2 receptor antagonists, but did not change significantly in those samples from the patients who were receiving H2 receptor antagonists.

CONCLUSIONS

Enteral feeding stimulates the secretion of hydrogen ions, which are then buffered by ionized bicarbonate secreted by the nonparietal gastric cells generating CO2. In addition, the enzymatic digestion of nutrients in the stomach may also generate CO2. The increased intraluminal CO2 following enteral feeding results in a spuriously low gastric intramucosal pH reading. Our data suggest that tube feedings should be temporarily discontinued for at least 1 hr when measuring the gastric intramucosal pH. These data should, however, be used with caution when extrapolating to hemodynamically unstable patients. Furthermore, the consequences of frequent interruptions of enteral feeding need to be weighed against the possible benefits derived from the use of this monitoring tool.

Is the EWS/FLI-1 fusion transcript specific for Ewing sarcoma and peripheral primitive neuroectodermal tumor? A report of four cases showing this transcript in a wider range of tumor types

The presence of t(11;22)(q24;q12) is often considered diagnostic of Ewing sarcoma and peripheral primitive neuroectodermal tumor. We report four cases, all of which possessed this translocation as detected by reverse transcriptase polymerase chain reaction and confirmed by sequencing with or without fluorescent in situ hybridization, but none of which were Ewing sarcoma or peripheral primitive neuroectodermal tumor by histological criteria. Two were polyphenotypic tumors and two were mixed embryonal and alveolar rhabdomyosarcomas. Only one case was positive for MIC2 by immunohistochemistry and only in a rare cell. Two cases (one polyphenotypic tumor and one rhabdomyosarcoma) had double minute chromosomes with > 100 copies of the MDM2 gene. The presence of the t(11;22)(q24;ql2) translocation should probably not be considered diagnostic of Ewing sarcoma and peripheral primitive neuroectodermal tumor in the absence of supporting histological evidence. The presence of this translocation in Ewing sarcoma and peripheral primitive neuroectodermal tumor has been taken as evidence that these two tumors are related. Extending this relationship to include some polyphenotypic tumors and some rhabdomyosarcomas may not be justified unless additional evidence is gathered. Pathologists and oncologists will need to decide whether treatment regimens for tumors are better based on phenotype rather than genotype when these two profiles are seemingly in conflict.

An unusual cerebellar primitive neuroectodermal tumor with t(11;22) translocation: pathological and molecular analysis

Peripheral primitive neuroectodermal tumors (PNETs) consistently demonstrate a reciprocal translocation, t(11;22)(q24;q12). This translocation has not been found in PNETs of the central nervous system including the cerebellar medulloblastoma. We report an unusual cerebellar PNET in a 4-year-old boy in which tumor cells were surrounded by pools of Alcian blue-positive material. Tumor cells were immunoreactive for neuron-specific enolase and synaptophysin. Electron microscopy revealed well-developed rough endoplasmic reticulum, cell processes with intermediate filaments, microtubules, and dense core granules, and extracellular material reminiscent of mucopolysaccharide. Reverse transcriptase polymerase chain reaction (PCR) revealed an 11;22 translocation-specific PCR product. Clinically the tumor was a cerebellar PNET with leptomeningeal dissemination and there was no evidence to suggest that it was metastatic. Histopathology, however, was indicative of an unusual PNET that also manifested t(11;22) and was associated with an aggressive clinical course.

SBH-1, a novel Reed-Sternberg-like cell line capable of inducing tumors in SCID mice: immunophenotypic, cytogenetic, and cytokine expression profiles

A new cell line, SBH-1, with the morphologic, immunophenotypic, and karyotypic features consistent with those of Reed-Sternberg (RS) and Hodgkin (H) cells, has been established from the pleural effusion of a patient. The cytologic appearance of SBH-1 cells is characteristic of multinucleate RS and mononuclear H cells, all containing inclusion-like nucleoli. The SBH-1 cells express CD30, CD15, CD25, CD71, CD45, CD20, CD22, and bcl-2 protein and are negative for epithelial membrane antigen. Cytogenetic analysis showed multiple clonal abnormalities with breakpoints at 14q32, 6q21, and 11q23. The Ig heavy chain genes and both Ig light chain genes were rearranged in SBH-1 cells, whereas the bcl-2 gene was in germline configuration. Messages for the cytokines interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha, and transforming growth factor-beta and the cytokine receptors IL-2R, IL-4R, IL-6R, and IL-7R were detected by reverse transcription-polymerase chain reaction analysis. Xenotransplantation of SBH-1 cells into severe combined immunodeficient (SCID) mice led to local and disseminated tumor growth. The cytologic, histologic, and immunohistochemical features of SBH-1 cells in SCID mouse tumors were typical of RS and H cells. The SBH-1 cell line will be useful in the study of RS and H cell biology, inasmuch as it represents a cell line obtained from a previously untreated patient.

Concurrent RhGM-CSF does not offset myelosuppression from intensive chemotherapy: randomized placebo-controlled study in childhood acute lymphoblastic leukemia

To determine whether recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) can offset the myelosuppressive effects of intensive chemotherapy, we carried out a double-blind placebo-controlled trial in which 40 patients with acute lymphoblastic leukemia (ALL) were randomized into two groups of 20 each. One group received rhGM-CSF (5.5 micrograms/kg SC) coadministered with chemotherapy and the other, placebo coadministered with chemotherapy from day 5 to day 11 and from day 19 to day 25 of the 28-day intensification phase of our institutional high-risk protocol for childhood ALL. The results indicate that, at the dose and schedule used, rhGM-CSF did not prevent neutropenia or shorten the number of days required to complete this phase of therapy. In addition, the treated and placebo groups showed no significant difference in absolute neutrophil counts, number of days with neutropenia, number of days with fever, number of days spent in hospital, or number of days on antibiotics during the 28-day study period. There was also no difference between the two groups in the number, type, or severity of infectious episodes. Two of 20 patients in the treatment group have relapsed, whereas none of the patients in the placebo group has yet relapsed (follow-up: 3-37 months), but these events were not statistically significant. We conclude that treatment with rhGM-CSF at the dose and schedule employed is not clinically beneficial.

Acute tumour lysis syndrome complicating treatment of stage IVS neuroblastoma in infants under six months old

Acute tumour lysis syndrome (ATLS) is a common complication of the treatment of haematopoietic malignancies. It is also well recognized in many nonhaematopoeitic malignancies of adults. There are very few reports of the syndrome occurring during therapy for the nonhaematopoeitic malignancies of childhood, and none has previously been reported in the treatment of neuroblastoma. We report the cases of four patients presenting to The Hospital for Sick Children (HSC) between 1985 and 1992 who developed ATLS during treatment for stage IVS neuroblastoma. ATLS is a significant risk in patients undergoing therapy for stage IVS neuroblastoma, particularly where this has been delayed.