Recent Developments in Species Sensitivity Distribution Modeling.

The species sensitivity distribution (SSD) is a statistical approach that is used to estimate either the concentration of a chemical that is hazardous to no more than x% of all species (the HCx) or the proportion of species potentially affected by a given concentration of a chemical. Despite a significant body of published research and critical reviews over the past 20 yr aimed at improving the methodology, the fundamentals remain unchanged. Although there have been some recent suggestions for improvements to SSD methods in the literature, in general, few of these suggestions have been formally adopted. Furthermore, critics of the approach can rightly point to the fact that differences in technical implementation can lead to marked differences in results, thereby undermining confidence in SSD approaches. Despite the limitations, SSDs remain a practical tool and, until a demonstrably better inferential framework is available, developments and enhancements to conventional SSD practice will and should continue. We therefore believe the time has come for the scientific community to decide how it wants SSD methods to evolve. The present study summarizes the current status of, and elaborates on several recent developments for, SSD methods, specifically, model averaging, multimodality, and software development. We also consider future directions with respect to the use of SSDs, with the ultimate aim of helping to facilitate greater international collaboration and, potentially, greater harmonization of SSD methods. Environ Toxicol Chem 2021;40:293-308. © 2020 SETAC.

Revisions to the derivation of the Australian and New Zealand guidelines for toxicants in fresh and marine waters.

The Australian and New Zealand Guidelines for Fresh and Marine Water Quality are a key document in the Australian National Water Quality Management Strategy. These guidelines released in 2000 are currently being reviewed and updated. The revision is being co-ordinated by the Australian Department of Sustainability, Environment, Water, Population and Communities, while technical matters are dealt with by a series of Working Groups. The revision will be evolutionary in nature reflecting the latest scientific developments and a range of stakeholder desires. Key changes will be: increasing the types and sources of data that can be used; working collaboratively with industry to permit the use of commercial-in-confidence data; increasing the minimum data requirements; including a measure of the uncertainty of the trigger value; improving the software used to calculate trigger values; increasing the rigour of site-specific trigger values; improving the method for assessing the reliability of the trigger values; and providing guidance of measures of toxicity and toxicological endpoints that may, in the near future, be appropriate for trigger value derivation. These changes will markedly improve the number and quality of the trigger values that can be derived and will increase end-users' ability to understand and implement the guidelines in a scientifically rigorous manner.

LSD and structural analogs: pharmacological evaluation at D1 dopamine receptors.

The hallucinogenic effects of lysergic acid diethylamide (LSD) have been attributed primarily to actions at serotonin receptors. A number of studies conducted in the 1970s indicated that LSD also has activity at dopamine (DA) receptors. These latter studies are difficult to interpret, however, because they were completed before the recognition of two pharmacologically distinct DA receptor subtypes, D1 and D2. The availability of subtype-selective ligands (e.g., the D1 antagonist SCH23390) and clonal cell lines expressing a homogeneous receptor population now permits an assessment of the contributions of DA receptor subtypes to the DA-mediated effects of LSD. The present study investigated the binding and functional properties of LSD and several lysergamide and analogs at dopamine D1 and D2 receptors. Several of these compounds have been reported previously to bind with high affinity to serotonin 5HT2 (i.e., 3H-ketanserin) sites in the rat frontal cortex (K0.5 5-30 nM). All tested compounds also competed for both D1-like (3H-SCH 23390) and D2-like (3H-spiperone plus unlabeled ketanserin) DA receptors in rat striatum, with profiles indicative of agonists (nH < 1.0). The affinity of LSD and analogs for D2 like receptors was similar to their affinity for 5HT2 sites. The affinity for D1 like receptors was slightly lower (2- to 3-fold), although LSD and several analogs bound to D1 receptors with affinity similar to the prototypical D1 partial agonist SKF38393 (K0.5 ca. 25 nM). A second series of experiments tested the binding and functional properties of LSD and selected analogs in C-6 glioma cells expressing the rhesus macaque D1A receptor.(ABSTRACT TRUNCATED AT 250 WORDS)

Change in nasal resonance over time: a clinical study.

Fifteen of the 20 patients who had been judged by a speech pathologist and two surgeons to have had poor resonance following surgical treatment were recalled in order to review factors that may have been related to this poor result. In the present study, the poor-resonance patients were reanalyzed for present status given that they had received no further surgical intervention. The results indicate that over one-half of those patients now have normal resonance; this gives the patients who were repaired by the Cronin technique an 89 percent probability of achieving normal resonance. The age of the patient at the time of evaluation appears to be an important factor. Patients judged as "poor-resonance results" were more likely to be less than 5 years of age, but as they matured, judgment of "resonance" indicated improvement.

The Cronin push-back palate repair with nasal mucosal flaps: a speech evaluation.

This is a retrospective study of 92 cleft palate patients who had been repaired with the Cronin push-back palate repair with nasal mucosal flaps. The patients were evaluated by a speech pathologist for intelligibility, articulation, and resonance and rated using a 5-point scale devised for this study. Readily intelligible speech was present in 78 percent. Normal articulation was present in 66 percent. Normal resonance was present in 78 percent of the total subject group. Secondary procedures were performed in 14 percent of the group. Repaired clefts of the soft palate achieved a high rate of normal intelligibility, articulation, and resonance. Repaired submucous clefts and short palates achieved the lowest percent of normal articulation and resonance. Educational placement, hearing, and type of structural deformity all appear to influence the ultimate communication outcome.

Phonological proficiency of two cleft palate toddlers with school-age follow-up.

This study provides a comprehensive analysis of the speech-sound production of two children with repaired bilateral cleft lip and palate. Speech samples were obtained during videotaping of spontaneous interactions between the children and their parent(s) when the subjects were between 29 and 37 months of age. Re-evaluation of both language and phonological abilities was accomplished when the children were between 5 and 7 years of age. Based on phonemic transcription of these data, error matrices were prepared illustrating word-initial and word-final consonants produced. Place and manner of consonant production were analyzed and the individual phonological processes employed by each child were discussed. Results indicated individual differences between the subjects in that one subject's emerging phonological system was more characteristic of developmental delay while the other was more characteristic of structural inadequacy. These differences have implication for the management of preschool cleft palate children.

A hospital throughput model in the context of long waiting lists.

In a public health system, one of the problems is the size of the waiting list for admission to hospital. This research involves establishing a method of analysing the general surgery waiting list problem at hospital and district level. While there are many aspects to such a study, this paper concentrates on a linear programming model to plan the aggregate throughput of the general surgical department. Preliminary results from applying the techniques to actual health districts in the United Kingdom are reported.