Gold Nanoparticle Paper Immunoassays for Sensing the Presence of Vibrio parahaemolyticus in Oyster Hemolymph.

Seafood contamination with Vibrio bacteria is a problem for aquaculture, especially with oysters, which are often consumed raw. Current methods for diagnosing bacterial pathogens in seafood involve lab-based assays such as polymerase chain reaction or culturing, which are time consuming and must occur in a centralized location. Detection of Vibrio in a point-of-care assay would be a significant tool for food safety control measures. We report here a paper immunoassay that can detect the presence of Vibrio parahaemolyticus (Vp) in buffer and oyster hemolymph. The test uses gold nanoparticles conjugated to polyclonal anti-Vibrio antibodies in a paper-based sandwich immunoassay. A sample is added to the strip and wicked through by capillary action. If Vp is present, it results in a visible color at the test area that can be read out by eyes or a standard mobile phone camera. The assay has a limit of detection of 6.05 × 105 cfu/mL and a cost estimate of $5 per test. Receiver operating characteristic curves with validated environmental samples showed a test sensitivity of 0.96 and a specificity of 1.00. Because the assay is inexpensive and can be used on Vp directly without the requirement for culturing, or sophisticated equipment, it has the potential to be used in fieldable settings.

Symbolic play provides a fertile context for language development.

In this study, we test the hypothesis that symbolic play represents a fertile context for language acquisition because its inherent ambiguity elicits communicative behaviors that positively influence development. Infant-caregiver dyads (N = 54) participated in two 20-minute play sessions six months apart (Time 1 = 18 months, Time 2 = 24 months). During each session, the dyads played with two sets of toys that elicited either symbolic or functional play. The sessions were transcribed and coded for several features of dyadic interaction and language; infants' linguistic proficiency was measured via parental report. The two contexts elicited different communicative and linguistic behaviors. Notably, the symbolic play condition resulted in significantly greater conversational turn-taking than functional play, and also resulted in the greater use of questions and mimetics in infant-directed speech (IDS). In contrast, caregivers used more imperative clauses in functional play. Correlational and regression analyses showed that frequent properties of symbolic play (i.e., turn-taking, yes-no questions, mimetics) were positively related to infants' language proficiency, whereas frequent features of functional play (i.e., imperatives in IDS) were negatively related. The results provide evidence supporting the hypothesis that symbolic play is a fertile context for language development, driven by the need to negotiate meaning.

Optimization of paper-based nanoparticle immunoassays for direct detection of the bacterial pathogen V. parahaemolyticus in oyster hemolymph.

The detection of foodborne pathogens is critical for disease control and infection prevention, especially in seafood consumed raw or undercooked. Paper-based diagnostic tools are promising for rapid fieldable detection and provide a readout by eye due to the use of gold nanoparticle immunoprobes. Here we study different strategies to overcome these challenges in a real biological matrix, oyster hemolymph, for the detection of the pathogenic bacteria Vibrio parahaemolyticus (Vp). Nanoparticle surface chemistry, nitrocellulose speed and blocking, running steps, and antibody concentrations on the NP and nitrocellulose were all studied. Their effect on paper immunoassay signal intensity was quantified to determine optimal conditions, which enabled the detection of Vp directly from hemolymph below pathogenic concentrations.

The effect of amniotomy on urine protein creatinine ratio test accuracy.

Introduction: While the gold standard for evaluation of maternal urinary protein is a 24-hr urine collection, spot urine protein/creatinine ratio has been instituted as an alternative for quantification proteinuria. Though it seems intuitive to obtain a catheterized urine sample on patients with ruptured amniotic membranes, it is a common practice to forgo this step under the argument that there is no data to show its necessity. Data on the effect of amniotomy, spontaneous or artificial, on the accuracy of the protein/creatinine ratio are scant. The present study was designed to address this issue and objectively compare protein/creatinine ratio values on samples obtained from the same patient before and after amniotomy. Methods: We conducted a prospective non-interventional study. Women presenting in active labor or for labor induction with intact amnion were enrolled. Separate random catch urines for the protein/creatinine ratio were obtained prior to and immediately after spontaneous or assisted amniotomy. The urine samples were analyzed in the hospital chemistry department, and the results were compared. Results: Of the 137 patients consented, 63 had pre- and post-amniotomy protein/creatinine ratios collected. The mean age was 28.5±5.6 y, Gravidity 2.7±1.6, Gestational age 39.2±1.8 wks, and BMI 31.6±6.4 kg/m2. Comorbidities included gestational diabetes (5/63, 7.9%), chronic hypertension (3/63, 4.7%), and pre-eclampsia (5/63, 7.9%). Post-amniotomy protein/creatinine ratio was significantly higher than pre-amniotomy ratio (1.3±2.5 vs 0.34±0.83, p<0.001). In addition, the number of patients with protein/creatinine ratio greater than 0.3 was higher post-amniotomy than pre-amniotomy (41/63 vs 14/63, p<0.001). Conclusion: Amniotomy results in a false elevation of the protein/creatinine ratio in term patients. Urine samples should be obtained by catheterization in the setting of ruptured membranes to reduce falsely elevated results. Although the same can be assumed for other gestational ages, further studies including this population need to be conducted.

Symbolic play promotes non-verbal communicative exchange in infant-caregiver dyads.

Symbolic play has long been considered a fertile context for communicative development (Bruner, 1983, Child's talk: Learning to use language, Oxford University Press, Oxford; Vygotsky, 1962, Thought and language, MIT Press, Cambridge, MA; Vygotsky, 1978, Mind in society: The development of higher psychological processes. Harvard University Press, Cambridge, MA). In the current study, we examined caregiver-infant interaction during symbolic play and compared it to interaction in a comparable but non-symbolic context (i.e., 'functional' play). Fifty-four (N = 54) caregivers and their 18-month-old infants were observed engaging in 20 min of play (symbolic, functional). Play interactions were coded and compared across play conditions for joint attention (JA) and gesture use. Compared with functional play, symbolic play was characterized by greater frequency and duration of JA and greater gesture use, particularly the use of iconic gestures with an object in hand. The results suggest that symbolic play provides a rich context for the exchange and negotiation of meaning, and thus may contribute to the development of important skills underlying communicative development. Statement of contribution Current knowledge Symbolic play has long been linked to communicative development. We do not know the extent to which the social context of symbolic play fosters communicative skills. Present study We test whether key communicative acts (joint attention, gesture) are more common in infant-caregiver dyads during symbolic versus functional play. Joint attention was established more often and sustained for longer periods in symbolic play than in functional play. Infants and caregivers produced more in-hand representational gestures in symbolic compared to functional play.