A minimally invasive procedure for blood extraction from Xenopus laevis allows follow up studies without euthanasia

Blood extraction is extremely important for the development of scientific research; however, the existing methods for amphibian´s blood sampling are invasive, mainly leading to the euthanasia of the animal. Therefore, less intrusive methods that allow the obtention of multiple samples from the same individual, are needed as an alternative to the common methods available. Hence, the aim of this study was to propose a minimally invasive method for obtaining blood from the hind leg of Xenopus laevis, that allows continuous sampling without compromising the wellbeing of the organisms. With this method, it was possible to extract blood and plasma from adults and juveniles, and the amount of sample was enough to perform biochemical and molecular assays to assess the viability of the blood. The results also revealed that this method is a convenient alternative to obtain blood without affecting the welfare of the experimental organisms, avoiding the cull of the animals, and the samples are viable for their use in follow up studies.

Harlequin color change in a premature infant: A case report

Key Clinical Message

This case of HCC report contributes to the knowledge of HCC in China. In this case, the longer duration of the color change observed in this case compared to previous reports, which will be useful for all medical practitioners.

Abstract

Harlequin color change (HCC) is a benign skin color change that lasts for a short time with no obvious physical abnormalities. Its pathogenesis is still unclear. It occurs in newborns, especially premature infants. However, few cases of HCC have been reported in China. Herein, we report a case of HCC. The infant was born at 34 + 4 weeks of gestation and was admitted to the hospital due to metabolic acidosis and neonatal pneumonia after birth. On the third day after birth, there were two red bands with obvious edges along the body centreline, and the erythema characteristics were consistent with those of HCC. The immature hypothalamus of newborns may cause the occurrence of HCC. At the same time, some drugs (midazolam), hypoxemia, and blood sampling may also be associated with HCC during neonatal hospitalization. All doctors should be thoroughly knowledgeable about the clinical characteristics of HCC and avoid using unnecessary drugs during treatment.

Direct and Indirect Measurements of Sex Hormones in Rodents During Fear Conditioning

Fear conditioning (FC) is a widely accepted tool for the assessment of learning and memory processes in rodents related to normal and dysregulated acquired fear. The study of sex differences in fear learning and memory is vast and currently increasing. Sex hormones have proven to be crucial for fear memory formation in males and females, and several methods have been developed to assess this hormonal state in rats and mice. Herein, we explain a routine FC and extinction protocol, together with the evaluation of sex hormonal state in male and female rodents. We explain three protocols for the evaluation of this hormonal state directly from blood samples extracted during the procedure or indirectly through histological verification of the estrous cycle for females or behavioral assessment of social hierarchies in males. Although females have typically been considered to present great variability in sex hormones, it is highlighted that sex hormone assessment in males is as variable as in females and equally important for fear memory formation. The readout of these protocols has had a great impact on different fields of fear learning and memory study and appears essential when studying FC. The proven interaction with drugs involved in the modulation of these processes makes sex hormone assessment during FC a valuable tool for the development of effective treatments for fear-related disorders in men and women. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Fear conditioning and fear extinction Basic Protocol 2: Blood collection for direct measurement of sex hormone levels in fear conditioning Basic Protocol 3: Indirect measurement of sex hormones in females during fear conditioning Basic Protocol 4: Assessment of dominance status in males before a fear conditioning protocol Support Protocol: Construction of a confrontation tube.

Nanophotonic-Carbohydrate Lab-on-a-Microneedle for Rapid Detection of Human Cystatin C in Finger-Prick Blood

Miniaturized total analysis systems, for the rapid detection of disease biomarkers, with features including high biomarker sensitivity, selectivity, biocompatibility, and disposability, all at low cost are of profound importance in the healthcare sector. Within this frame of reference, we developed a lab-on-a-carbohydrate-microneedle biodevice by integrating localized surface plasmon resonance (LSPR) paper-based substrates with biocompatible microneedles of high aspect ratio (>60:1 length:width). These microneedles are completely fabricated with carbohydrate (maltose) and further coated with poly lactic-co-glycolic acid (PLGA), which together serves the purpose of fluid channels. The porous nature of PLGA, in addition to drawing blood by capillary action, filters out the whole blood, allowing only the blood plasma to reach the biorecognition layer of the developed biodevice. While the use of maltose provides biocompatibility to the microneedle, the axial compression and transverse load analysis revealed desired mechanical strength of the microneedle, with mechanical failure occurring at 11N and 9 N respectively for the compressive and transverse load. For a proof-of-principle demonstration, the developed biodevice is validated for its operational features by direct detection of cystatin C in finger-prick blood and up to a concentration of 0.01 μg/mL in buffered conditions using the LSPR technique. Furthermore, by changing the biorecognition layer, the use of the developed needle can be extended to other disease biomarkers, and therefore the innovation presented in this work represents a hallmark in the state of the art of lab-on-a-chip biodevices.