Reconciling Coulter Counter and laser diffraction particle size analysis for aquaculture monitoring.

The disaggregated inorganic grain size (DIGS) of bottom sediment analyzed with a Coulter Counter (CC) has been used to show that the fraction of sediment deposited in flocs (floc fraction) increased in both the near and far field after the introduction of open cage salmon aquaculture, altering benthic habitat and species composition. As a result, DIGS was identified as a potential indicator of regional environmental changes due to aquaculture. Laser diffraction is an attractive alternative to the CC because of its greater efficiency and larger size range. To determine if a laser diffraction instrument, Beckman-Coulter LS 13 320 (LS), could replace the CC within a Canadian national aquaculture monitoring program, the DIGS of 581 samples from five different regions in eastern Canada were analyzed with an LS and a CC. Results show that the LS could not be used to calculate floc fraction. Instead, % sortable silt and the volume % of inorganic particles < 16 µm were evaluated as alternative proxies for fine sediment properties. LS and CC values for these parameters were correlated, but they were significantly different and the relationship between the instruments was dependent on the area sampled. The LS did not capture variations between areas seen in the CC DIGS data. Where the DIGS from the CC found no sorting in the finest size classes, all the LS samples had similar size distributions characterized by smooth modal peaks. The LS and CC both return values that can be used to monitor changes in the deposition of fine-grained sediment, but the LS cannot determine changes in floc deposition and caution is required if comparing different sedimentary environments.

Tablet-based electroencephalography diagnostics for patients with epilepsy in the West African Republic of Guinea.

BACKGROUND AND PURPOSE: Epilepsy is most common in lower-income settings where access to electroencephalography (EEG) is generally poor. A low-cost tablet-based EEG device may be valuable, but the quality and reproducibility of the EEG output are not established. METHODS: Tablet-based EEG was deployed in a heterogeneous epilepsy cohort in the Republic of Guinea (2018-2019), consisting of a tablet wirelessly connected to a 14-electrode cap. Participants underwent EEG twice (EEG1 and EEG2), separated by a variable time interval. Recordings were scored remotely by experts in clinical neurophysiology as to data quality and clinical utility. RESULTS: There were 149 participants (41% female; median age 17.9 years; 66.6% ≤21 years of age; mean seizures per month 5.7 ± SD 15.5). The mean duration of EEG1 was 53 ± 12.3 min and that of EEG2 was 29.6 ± 12.8 min. The mean quality scores of EEG1 and EEG2 were 6.4 [range, 1 (low) to 10 (high); both medians 7.0]. A total of 44 (29.5%) participants had epileptiform discharges (EDs) at EEG1 and 25 (16.8%) had EDs at EEG2. EDs were focal/multifocal (rather than generalized) in 70.1% of EEG1 and 72.5% of EEG2 interpretations. A total of 39 (26.2%) were recommended for neuroimaging after EEG1 and 22 (14.8%) after EEG2. Of participants without EDs at EEG1 (n = 53, 55.8%), seven (13.2%) had EDs at EEG2. Of participants with detectable EDs on EEG1 (n = 23, 24.2%), 12 (52.1%) did not have EDs at EEG2. CONCLUSIONS: Tablet-based EEG had a reproducible quality level on repeat testing and was useful for the detection of EDs. The incremental yield of a second EEG in this setting was ~13%. The need for neuroimaging access was evident.

Contaminants at the sediment-water interface: implications for environmental impact assessment and effects monitoring.

Many contaminants in aquatic environments are associated with loosely packed aggregates of particulate material called flocs. Flocculation allows contaminants to accumulate at the sediment-water interface and it packages them in a form that is readily available for ingestion by filter feeding organisms. Unfortunately, most samplers being used for environmental assessment and monitoring suspend this material on impact and fail to sample this critical component of the seabed. In this study we use a slo-corer to collect seabed samples with an undisturbed surface layer and a Gust microcosm erosion chamber to erode the surface of the cores at increasing shear stresses. Results from two different sites, one impacted by tailings from historic gold mining and the other by open-pen salmon aquaculture, showed the levels of metals suspended at stresses below 0.24 Pa were greater than in the underlying sediment. Sampling this highly mobile surface layer is critical for determining the total contaminant load in bottom sediments and, more importantly, this layer represents the most readily available material for suspension. The loss of this layer during sampling could lead to inaccurate measurements of contaminant levels during environmental assessment and effects monitoring. A re-evaluation of the ISO standard for bottom sediment sampling is recommended.

Intravenous immunoglobulin therapy in the treatment of BK viremia and nephropathy in pediatric renal transplant recipients.

Polyoma BKVN is a significant cause of allograft dysfunction and loss in renal transplant recipients. Reduction in immunosuppression is accepted as first-line therapy to decrease viral load and prevent allograft injury and dysfunction. We report our experience with persistent BKV after reduction in immunosuppression followed by successful clearance of BKV in three pediatric renal transplant recipients and histological resolution of BKVN in a fourth patient following therapy with IVIG. Once BKV was detected, immunosuppression was reduced and BKV was monitored until clearance was achieved. All four patients were given IVIG in a dose of 2 g/kg. Allograft function remained stable in all patients. Early routine screening for BKV allows early intervention to prevent the development of BKVN and permanent allograft damage. While immunosuppression reduction is a logical first-line therapy, second-line therapy is not well established. IVIG seems to be an effective treatment for persistent BKV after reduction in immunosuppression and for BKVN and can therefore be considered as a therapeutic option in these patients.

Neurology residents' education in functional seizures.

We report a survey of neurology residency program directors (PDs) and recent neurology residency graduates about the education provided during residency on functional seizures (FS), a subtype of functional neurological disorder (FND). The purpose of our study was to assess the education gap for neurology residents about FS since patients with FS are frequently seen by neurologists, who typically conduct the evaluation and share the findings with the patient. A survey was sent to 93 Neurology residency program directors and 71 recent graduates. We obtained a low response rate of 17%. Results of the survey revealed that the most frequent settings for education on FS were within a clinical rotation in the Epilepsy Monitoring Unit (68.8% of PDs and 88.7% of recent graduate respondents) and via a single didactic lecture (81.3% of PDs and 80.3% of recent graduate respondents). The majority of programs did not provide a curriculum for training and feedback on best practices in communicating the diagnosis or on evidence-based treatments. Eighteen percent of neurology residents reported not learning how to communicate the diagnosis of FS to patients, while 77% responded that they were not taught about treatment. These results illustrate a curriculum gap in what neurology residents are taught about diagnosis and management of FS (and FND). We propose a standardized model that can be adapted in residencies.

Myocardial toxoplasmosis complicating cardiac transplant.

The increase in numbers of immunocompromised patients has been reflected by an increasing frequency of opportunistic infections. Of these, Toxoplasma gondii has been reported as a significant human pathogen following cardiac transplantation. In this setting, quiescent toxoplasma myocardial cysts may become active after implantation into a therapeutically immunosuppressed host. The consequences of infection are significant and carry a high morbidity and mortality. We present the clinical and pathologic characteristics of a patient with toxoplasma infection complicating cardiac transplant and review previously reported cases of this entity.

Tailoring aortoplasty for repair of fusiform ascending aortic aneurysms.

To evaluate the effectiveness of tailoring aortoplasty used to treat fusiform aneurysms of the ascending aorta, we reviewed the results of operation in 17 patients. Nine patients had tailoring aortoplasty alone, and 8 patients had aortoplasty with Dacron wrap of the ascending aorta. Fourteen of 17 patients were discharged from the hospital, and 12 patients were alive at follow-up between 2 and 120 months. Of two late deaths, neither was due to aneurysmal disease. Actuarial survival at 1 and 10 years was 81% and 63%, respectively. In selected cases, tailoring aortoplasty can achieve long-term results comparable with those of resection and graft replacement of fusiform ascending aortic aneurysms.

In vitro activity of clarithromycin, cefprozil, and other common oral antimicrobial agents against gram-positive and gram-negative pathogens.

Macrolide and beta-lactam antimicrobial agents are frequently used for the treatment of upper and lower respiratory tract infections and skin or skin structure infections. To evaluate the relative in vitro activity of these antimicrobial drugs against organisms commonly involved in these infections, we tested clarithromycin, erythromycin, cefprozil, cefuroxime, cefaclor, cephalexin, amoxicillin, amoxicillin/clavulanate, and doxycycline against 174 gram-positive and gram-negative clinical isolates, including Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, group A beta-hemolytic streptococci, alpha-hemolytic streptococci, Escherichia coli, and Klebsiella pneumoniae. Manual broth microdilution susceptibility testing was used with a standard inoculum of 5 x 10(4) colony-forming units/well at pH of 7.2. Clarithromycin was the most active agent against streptococci. Methicillin-susceptible S aureus exhibited resistance to both clarithromycin and erythromycin, but was susceptible to cefprozil, cefuroxime, amoxicillin/clavulanate, and doxycycline. Cefprozil was at least as active as cefuroxime, cefaclor, and cephalexin against all organisms tested, but was fourfold less active than doxycycline against E coli and 16-fold less active than clarithromycin versus S pneumoniae. The gram-negative isolates tested showed resistance to clarithromycin and erythromycin; however, cefprozil was as active as amoxicillin/clavulanate against K pneumoniae and E coli. These results demonstrate that clarithromycin provides superior in vitro activity against common streptococci, while cefprozil, cefuroxime, amoxicillin/clavulanate, and doxycycline provide greater activity against methicillin-susceptible S aureus, K pneumoniae, and E coli. Prospective clinical trials are needed to determine the clinical significance of these findings.

Assessment of the performance of a capture immunoassay for the bone isoform of alkaline phosphatase in serum.

We report the analytical validation of an immunocapture assay for the bone isoform of alkaline phosphatase in serum. A between batch imprecision of less than 10% was found, being about 8% at the upper limit of the reference range, and with a detection limit of 0.8 IU/l at 37 degrees C. The crossreactivity of the method with the liver isoform was found to be in the range of 3-13% depending on the method employed. Unexpectedly the correlation of results with a non-immunological method for the quantitation of bone ALP showed significant differences between samples from children and patients with Paget's disease, with an apparent lower level of capture in the case of children. These data suggest that there may be differences in the epitope recognised by the antibody, which may be due to the presence of different forms of bone enzyme in these two populations. The significance of these observations is not clear at this stage.

Development and validation of a robust specific enzyme mediated assay for phenylalanine in serum.

The specificity of a phenylalanine dehydrogenase, particularly with respect to cross reactivity toward tyrosine, has been shown to be pH dependent, being minimal at high pH. The dehydrogenase step has been coupled to colorimetric detection of NADH using a tetrazolium salt. The assay shows no significant cross reactivity towards a range of amino acids or drugs and correlates well with an established HPLC technique.

Development of an enzyme-mediated assay for phenylalanine in blood spots.

We describe the optimization of a rapid procedure for the elution of phenylalanine from blood spots and the estimation of the amino acid eluted using an enzyme-mediated assay linked to a colorimetric detection system. The method is rapid, fully quantitative, interference-free, accurate and precise unlike many of the methods currently employed for phenylalanine determination. The performance of the proposed method may necessitate the review of reference ranges and cut-off assignment strategies.

Studies on paracetamol binding to serum proteins.

There is a limited amount of data on the binding of paracetamol to plasma proteins. It has been suggested that binding might influence the ability of some analytical methods to quantify the total amount of drug present in the plasma fraction--the basis of clinical experience in risk assessment and antidote usage. We have investigated the binding of paracetamol to plasma proteins using an ultrafiltration technique. In overdose and spiked uraemic plasma samples the mean percentage of paracetamol bound was 24.1 (1SD = 7.0) with no significant correlation with drug levels or degree of uraemia. There is a small but significant increase in binding with increasing serum albumin concentration both in plasma (rs = 0.549, P = 0.014) and in pure serum albumin solutions (rs = 0.848, P < 0.001).

Distribution of PACs in surficial sediments and bioavailability to mussels, Mytilus edulis of Halifax Harbour.

Surficial sediments and blue mussels were collected around the perimeter of Halifax Harbour. Samples were analysed for the levels and fingerprint of polycyclic aromatic compounds (PACs). The objective was to explore the relationship between contaminant profiles in sediments and in mussels and to explore the possibility of deducing their sources, pattern of deposition and circulation in the harbour. Combustion derived compounds predominated in both sets of samples, with more variability observed in the level of petroleum derived hydrocarbons in mussel samples. Biota-sediment accumulation factors (BSAF, dry/dry wt.) varied throughout the harbour, ranging from means of 0.006 to 1.26, where generally fluoranthene displayed the highest BSAF. Sediments and mussels give complementary views of the geographical distribution of contaminants, they reflect the state of benthic and pelagic habitats. Results observed for Halifax Harbour are discussed from the perspective of published data.

Thyroid hormone stimulation of extracellular signal-regulated kinase and cell proliferation in human osteoblast-like cells is initiated at integrin alphaVbeta3.

The aim of the present study was to examine whether triiodo-l-thyronine (T(3)) or l-thyroxine (T(4)) rapidly activated the mitogen-activated protein kinase (MAPK) intracellular signalling cascade in osteoblast-like cells and investigate whether this activation was initiated at the integrin alpha(V)beta(3) cell surface receptor. Using PCR and western blotting, the expression of integrin alpha(V)beta(3) mRNA and protein was demonstrated in the human osteoblast-like cell lines MG-63 and SaOS-2. The treatment of MG-63 cells with T(3) (10 nM) or T(4) (100 nM) for 10 min stimulated extracellular signal-regulated kinase activity (ERK, a component of the MAPK pathway) as determined by fluorescent immunocytochemistry and an immunocomplex activity assay (T(3) by 10.7-fold, P<0.01 and T(4) by 10.4-fold, P<0.01 compared with control). T(3) (10 nM) and T(4) (100 nM) also significantly stimulated thymidine incorporation into MG-63 cells by 2.3+/-0.7-fold (P<0.01) and 2.1+/-0.1-fold (P<0.05) respectively. To establish whether transient ERK activation via the integrin alpha(V)beta(3) cell surface receptor mediated these effects, MG-63 cells were pretreated for 30 min with the specific MAPK kinase inhibitor, U0126 (1 microM), or an anti-integrin alpha(V)beta(3)-blocking antibody. Both pretreatments significantly inhibited T(3)- and T(4)-stimulated ERK activation and abolished T(3)-stimulated thymidine incorporation (P<0.01). T(4)-stimulated incorporation was significantly inhibited from 2.1- to 1.3-fold above control (P<0.05). Thus, our results suggest that T(3) and T(4) rapidly stimulate ERK activation in MG-63 cells via integrin alpha(V)beta(3) and that one functional effect of this ERK activation is increased DNA synthesis.

Rapid protein determinations on ultrafiltrates prepared for free phenytoin quantification.

Ultrafiltration techniques for the separation of bound and free ligand are dependent on minimal amounts of protein-bound drug leakage through the membrane devices. A dye-impregnated test strip protein assay (Chemstrip-9) provides a rapid, visual assessment of membrane protein leakage. The test strips are sensitive to 200 mg/L of albumin in ultrafiltrates and do not react with as much as 4 mg/L of phenytoin.

Preliminary characterization studies on the Neisseria catarrhalis respiratory electron transport chain.

The Neisseria catarrhalis respiratory electron transport system was examined in a sonic type particulate membrane fraction and shown to have a moderately active succinate as well as nonpyridine nucleotide-dependent dl-lactate oxidoreductase and a very active tetramethyl-p-phenylenediamine oxidase. l-Malate and l-glutamate oxidation were found to be dependent on pyridine nucleotides and exclusively associated with a soluble (or nonmembranous) fraction. The primary cytochrome components in the electron transport system appear to be c-type in nature (555 nm and 550 nm) as well as cytochrome a(1) (600 nm) and cytochrome o.

Quantitation of the tetramethyl-p-phenylenediamine oxidase reaction in Neisseria species.

The tetramethyl-p-phenylenediamine oxidase reaction commonly used in the Kovacs oxidase test was quantitatively estimated for various Neisseria species employing standardized resting cell suspensions. This genus of microorganisms exhibited very high tetramethyl-p-phenylenediamine oxidase rates comparable to that of Azotobacter and Pseudomonas, and this reaction was found to be a valid measurement for the respiratory capability possessed by this group of organisms.

Direct comparison of performance characteristics of two immunoassays for bone isoform of alkaline phosphatase in serum.

A clinical need exists for a sensitive and specific assay for the quantitation of the bone isoform of alkaline phosphatase in serum. The majority of methods do not meet this requirement; however, the recent development of immunoassays for this isoform may provide a solution. In a detailed evaluation of two immunoassays, we found a degree of imprecision that enables the discrimination of changes within the reference range. The cross-reactivity of the liver isoform was found to be between 7.1% and 12.7% when two different methods of assessment were used. The comparison of results with an electrophoretic procedure showed that the immunocapture method recovered less of the bone isoform in samples from children than in samples from patients with Paget disease; no such difference was found with the immunometric method. This suggests that the immunocapture antibody may discriminate between different bone isoforms in children whereas the immunometric assay does not.