Use of the Barbiturate-Mercury Reaction in Clinical Laboratory ‘Screening’ for Barbiturate Poisoning

The barbiturate-mercuric-diphenylcarbazone reaction of Lubran is reviewed. A micromethod for emergency serum barbiturate determination is described. Three significant improvements are linearity of colour reaction, the use of cellulose paper in the extraction and the use of tin-free dichloromethane as the extractant. Experiences with this method and with a commercial ‘kit’ method are recorded.

Comparative Study of Thyroxine Assays Employing Kit Radio-Ligand Reagents

A comparative study of some ‘kit’ radiometric procedures for the determination of thyroxine in serum is reported. Four manufacturers' competitive-binding reagents and methods—three incorporating prior extraction and one employing column elution—are examined. Considerable discrepancies exist between the manufacturers' ‘standards’ which, in the main, account for the differences in results obtained by the different methods. Other deficiencies include susceptibility to metal ion interference, variation (up to 8%) in thyroxine extraction and non-specific, i.e. ‘mimic T-4’, measurement.

Radio-ligand reagent ‘kits’ need to be critically assessed before being used routinely. Separation of hypo-and hyperthyroid from euthyroid patients is achieved as well with some competitive protein-binding T-4 methods as with serum PBI.

Accuracy and Standardisation of Serum Thyroxine Assays

Serum thyroxine was assayed concurrently by at least two of three different radio-displacement analysis kits—‘Tetralute’ (Ames), ‘Tetrasorb’ (Abbott) and ‘Thyopac-4’ (Radiochemical Centre). Repeated and careful cross checking by each of the methods was carried out on the ‘standard’ sera supplied with the kits and on other commercially available control sera. Differences of −3 to + 32% in apparent T-4 concentration were found. An unacceptable variability in T-4 content amongst batches of the same control sera was also evident which can be explained only by a lack of constancy in the commercial serum T-4 ‘standards’.

The molar extinction coefficients, water and tri-iodothyronine contents of commercial ‘pure’ thyroxine preparations indicate purities of 89–99 %. An examination of published ‘euthyroid’ ranges and those found by the ‘kit’ radiometric methods suggests that many normal serum T-4 values are based on the use of an impure primary or doubtful secondary standard. A primary standardisation of the assay with thyroxine of known purity and of known concentration, as determined from its molar extinction at 324 nm is advocated. Using this procedure, the normal euthyroid range for serum T-4 is 55–148 nmol T4/1 (2.8–7.5 μg T-4I/100 ml) or close to it—in agreement with the earlier findings of Howarth and Maclagan (1969) and Ekins et al. (1969).

During the period studied, ‘Tetralute’ produced the most accurate results.

Terrestrial gamma radiation baseline mapping using ultra low density sampling methods

Baseline terrestrial gamma radiation maps are indispensable for providing basic reference information that may be used in assessing the impact of a radiation related incident, performing epidemiological studies, remediating land contaminated with radioactive materials, assessment of land use applications and resource prospectivity. For a large land mass, such as Queensland, Australia (over 1.7 million km(2)), it is prohibitively expensive and practically difficult to undertake detailed in-situ radiometric surveys of this scale. It is proposed that an existing, ultra-low density sampling program already undertaken for the purpose of a nationwide soil survey project be utilised to develop a baseline terrestrial gamma radiation map. Geoelement data derived from the National Geochemistry Survey of Australia (NGSA) was used to construct a baseline terrestrial gamma air kerma rate map, delineated by major drainage catchments, for Queensland. Three drainage catchments (sampled at the catchment outlet) spanning low, medium and high radioelement concentrations were selected for validation of the methodology using radiometric techniques including in-situ measurements and soil sampling for high resolution gamma spectrometry, and comparative non-radiometric analysis. A Queensland mean terrestrial air kerma rate, as calculated from the NGSA outlet sediment uranium, thorium and potassium concentrations, of 49 ± 69 nGy h(-1) (n = 311, 3σ 99% confidence level) is proposed as being suitable for use as a generic terrestrial air kerma rate background range. Validation results indicate that catchment outlet measurements are representative of the range of results obtained across the catchment and that the NGSA geoelement data is suitable for calculation and mapping of terrestrial air kerma rate.

Contamination of multidose butorphanol vials in small animal general practices

OBJECTIVES

To assess and quantify medetomidine contamination of butorphanol multidose vials in small animal general practices and determine if practice policies and procedures regarding drug handling, as determined by questionnaire, impact upon contamination level.

METHODS

Samples of butorphanol were withdrawn from in-use vials in participating practices in June and July 2013. Samples were analysed using high-performance liquid chromatography and mass spectrometry.

RESULTS

Forty-one samples were obtained from 31 practices. Contamination was detected in 29 samples from 10 mL vials. The mean (αsd) contamination was 0 · 275 (α0 · 393) µg/mL; maximum contamination in any vial was 2 · 034 µg/mL. There was no correlation between volume of the vial used and the level of contamination. None of the survey factors predicted contamination levels of the vials.

CLINICAL SIGNIFICANCE

Contamination of butorphanol multidose vials with medetomidine was common but the level of contamination was insufficient to cause detrimental effects in dogs if butorphanol were to be administered alone. The potential for sporadic higher levels of contamination must be taken into account, especially when using 50 mL vials when sedating critically ill cases, because there is a risk of clinical side effects.

Prolylcarboxypeptidase independently activates plasma prekallikrein (fletcher factor)

Prolylcarboxypeptidase isoform 1 (PRCP1) is capable of regulating numerous autocrines and hormones, such as angiotensin II, angiotensin III, αMSH1-13, and DesArg(9) bradykinin. It does so by cleaving a C-terminal PRO-X bond. Recent work also indicates that the human PRCP1 activates plasma prekallikrein (PK) to kallikrein on endothelial cells through an uncharacterized mechanism. This study aims to identify PRCP1 binding interaction and cleavage site on PK. Recently, a cDNA encoding a novel splice variant of the human PRCP1 was identified. This isoform differed only in the N-terminal region of the deduced amino acid sequence. Using structural and functional studies, a combination of peptide mapping and site-directed mutagenesis approaches were employed to investigate the interaction of PRCP1 with PK. Three PRCP peptides, in decreasing order of potency, from 1) the N-terminus of the secreted protein, 2) spanning the opening of the active site pocket, and 3) in the dimerization region inhibit PRCP activation of PK on endothelial cells. Investigations also tested the hypothesis that PRCP cleavage site on PK is between its C-terminal Pro 637 (P(637)) and Ala 638 (A(638)). Recombinant forms of PK with C-terminal alanine mutagenesis or a stop codon is activated equally as wild type PK by PRCP. In conclusion, PRCP1 interacts with PK at multiple sites for PK activation. PRCP1 also enhances FXIIa activation of PK, suggesting that its activation site on PK is not identical to that of FXIIa.

The structure and short-term stability of the emotional disorders: a dimensional approach

BACKGROUND

Factor-analytic studies have found that depressive, bipolar, post-traumatic, obsessive-compulsive, and anxiety disorders - jointly referred to as the emotional disorders - form an internalizing spectrum that includes distress and fear subfactors. However, placement of some disorders is uncertain. Also, prior research analysed dichotomous interview-based diagnoses or dimensional self-report measures. We investigated this structure using a third-generation measure - the Interview for Mood and Anxiety Symptoms (IMAS) - that combines strengths of a clinical interview with dimensional assessment.

METHOD

The interview was administered to 385 students and 288 psychiatric out-patients. Participants were reinterviewed 2 months later.

RESULTS

Exploratory and confirmatory factor analyses identified three factors: distress (depression, generalized anxiety, post-traumatic stress, irritability, and panic syndrome); fear (social anxiety, agoraphobia, specific phobia, and obsessive-compulsive); and bipolar (mania and obsessive-compulsive). The structure was consistent over time and across samples, except that panic and agoraphobia had higher factor loadings in patients. Longitudinal analyses revealed high temporal stability of the factors (test-retest r = 0.72 to 0.87), but also substantial disorder-specific stability.

CONCLUSIONS

This investigation - which bridges diagnostic and self-report studies - found three subfactors of internalizing psychopathology. It provided support for a new subfactor, clarified the placement of obsessive-compulsive and bipolar disorders, and demonstrated that this model generalizes across populations. The accumulating research suggests the need to recognize formally the close links among the emotional disorders, as well as empirical clusters within this spectrum. The IMAS demonstrated strong psychometric properties and can be useful for various research and clinical applications by providing dimensional, interview-based assessment of the emotional disorders.

The effect of a single, large bolus of vitamin D in healthy adults over the winter and following year: a randomized, double-blind, placebo-controlled trial

BACKGROUND/OBJECTIVES

Although single, high doses of vitamin D effectively maintain vitamin D sufficiency in several populations, no studies have evaluated healthy adults over winter, during which vitamin D status declines. This study investigated whether high-dose vitamin D3 given once to healthy adults before winter will (1) prevent the wintertime decline in vitamin D status, (2) promote vitamin D sufficiency 1 year following the dose and (3) prevent the rise of parathyroid hormone (PTH) concentrations.

SUBJECTS/METHODS

In this double-blind, placebo-controlled trial, we assessed plasma 25(OH)D and PTH concentrations at baseline, 5, 90 and 365 days after drug administration in 28 healthy adults. In all, >80% of subjects returned at each time point.

RESULTS

At baseline, the young, healthy participants had a mean plasma 25(OH)D concentration of 17.5±6.1 ng/ml. Only two subjects exhibited plasma 25(OH)D concentrations >30 ng/ml. At 5 days, subjects randomized to vitamin D3 had a higher mean plasma 25(OH)D concentration compared with the placebo group (39.1 vs 19.1 ng/ml, P<0.001). Plasma 25(OH)D concentrations returned to baseline at 90 and 365 days in the vitamin D3 group and remained unchanged in the placebo group. PTH and calcium concentrations were unrelated to changes in 25(OH)D levels and similar between groups over time.

CONCLUSIONS

A dose of 250,000 IU of vitamin D3 given once in November resulted in a robust increase in plasma 25(OH)D after 5 days, but it was unable to sustain this increase after 90 days. A larger or more frequent dosing regimen may be needed for long-term vitamin D sufficiency.

Selective Depletion of Alloreactive T Cells Leads to Long-Term Islet Allograft Survival across a Major Histocompatibility Complex Mismatch in Diabetic Mice

Islet cell transplantation as a therapy for type 1 diabetes has been limited by progressive graft loss. Significant immunosuppression including T-cell ablation has been used in an attempt to limit islet rejection. Here, we show that CD3+ lymphocytes depleted of alloreactive T cells selected from a mixed lymphocyte reaction (MLR), where responder BALB/c splenocytes stained with carboxyfluorescein succinimidyl ester (CFSE) were stimulated with irradiated C57BL/6 splenocytes for 5 days, infused into diabetic immunodeficient mice are capable of restoring a broad T-cell repertoire and specifically do not reject islet transplants from the strain (C57BL/6) used in the original depletion. These mice demonstrate reconstitution with CD4+ and CD8+ T cells, the capacity to reject third-party grafts (CBA), and restoration of interferon-γ (IFN-γ) responses to third-party alloantigens. Over time, both forkhead box P3-positive (Foxp3+) T regulatory cells (Tregs) and γδ T cells expand, suggesting a role for peripheral tolerance, in addition to the initial depletion of alloreactive T cells, in long-term islet graft survival. Our results suggest that immune restoration with CD3+ lymphocytes where alloreactive T cells are removed can restore cognate immunity without islet allograft loss and recurrence of diabetes.