Is the oocyte a non-professional phagocyte?

Although fertilization has been described as a series of events during which the spermatozoon penetrates the oocyte, introducing its nuclear contents, there is strong evidence that either gamete can be the active partner at different stages of this process. Indeed, while sperm motility is essential for its penetration of the egg vestments, immotile spermatozoa are capable of entering the ooplasm once they adhere to the oolemma. Entry of the spermatozoon into the oocyte appears to require two distinct but perhaps related events, namely gamete cell membrane fusion, at the level of the equatorial segment of the sperm acrosome with the oolemma, and a quasi-phagocytic event involving the incorporation by the oocyte of the rostral portion of the acrosome-reacted spermatozoon head within an oolemmal-derived vesicle. This review explores the biology of phagocytosis by macrophages and non-professional phagocytes, and in particular the roles played by phagocytosis-promoting receptors (FcgR, complement receptors and integrins), in both signal transduction and their linkage with the cytoskeleton. It asks whether the oocyte might not utilize similar mechanisms during its incorporation of the spermatozoon.     

Is It a Wave or a Tsunami? That is the Question

How to cite this article: Todi S. Is It a Wave or a Tsunami? That is the Question. Indian J Crit Care Med 2021;25(12):1331–1332.     

What Is a Host? Incorporating the Microbiota into the Damage-Response Framework

Since proof of the germ theory of disease in the late 19th century, a major focus of the fields of microbiology and infectious diseases has been to seek differences between pathogenic and nonpathogenic microbes and the role that the host plays in microbial pathogenesis. Remarkably, despite the increasing recognition that host immunity plays a role in microbial pathogenesis, there has been little discussion about what constitutes a host. Historically, hosts have been viewed in the context of their fitness or immunological status and characterized by adjectives such as immune, immunocompetent, immunosuppressed, immunocompromised, or immunologically impaired. However, in recent years it has become apparent that the microbiota has profound effects on host homeostasis and susceptibility to microbial diseases in addition to its effects on host immunity. This raises the question of how to incorporate the microbiota into defining a host. This definitional problem is further complicated because neither host nor microbial properties are adequate to predict the outcome of host-microbe interaction because this outcome exhibits emergent properties. In this essay, we revisit the damage-response framework (DRF) of microbial pathogenesis and demonstrate how it can incorporate the rapidly accumulating information being generated by the microbiome revolution. We use the tenets of the DRF to put forth the following definition of a host: a host is an entity that houses an associated microbiome/microbiota and interacts with microbes such that the outcome results in damage, benefit, or indifference, thus resulting in the states of symbiosis, colonization, commensalism, latency, and disease.     

IFN-γ signals a changing of the guards

After acute inflammation or infection, tissue-resident macrophages are replaced by inflammatory DCs and effector macrophages that arise from circulating monocytes. In this issue of Immunity, Goldszmid et?al. (2012) demonstrate a central role for NK cell-derived IFN-γ in signaling and facilitating this transition.     

Does the Use of a Checklist Help Medical Students in the Detection of Abnormalities on a Chest Radiograph?

The interpretation of chest radiographs is a complex task that is prone to diagnostic error, especially for medical students. The aim of this study is to investigate the extent to which medical students benefit from the use of a checklist regarding the detection of abnormalities on a chest radiograph. We developed a checklist based on literature and interviews with experienced thorax radiologists. Forty medical students in the clinical phase assessed 18 chest radiographs during a computer test, either with (n = 20) or without (n = 20) the checklist. We measured performance and asked participants for feedback using a survey. Participants that used a checklist detected more abnormalities on images with multiple abnormalities (M = 50.1%) than participants that could not use a checklist (M = 41.9%), p = 0.04. The post-experimental survey shows that on average, participants considered the checklist helpful (M = 3.25 on a five-point scale), but also time consuming (M = 3.30 on a five-point scale). In conclusion, a checklist can help medical students to detect abnormalities in chest radiographs. Moreover, students tend to appreciate the use of a checklist as a helpful tool during the interpretation of a chest radiograph. Therefore, a checklist is a potentially important tool to improve radiology education in the medical curriculum.     

Does the development of the perigeniculate nucleus support the notion of a hierarchical progression within the visual pathway?

The development of the visual pathway has been extensively studied. However, despite of the importance of the perigeniculate nucleus within this pathway, there is a lack of information concerning its development. The present study examined the dendritic development of perigeniculate nucleus cells using single cell injections in 400-500 microm thick fixed brain slices from kittens of different ages between postnatal day 0 and postnatal day 125. A total of 189 perigeniculate nucleus cells were reconstructed from serial sections for qualitative and quantitative analysis. Cells during the first month were characterized by an abundance of branch points and appendages. There was a significant (P>0.05), albeit variable, increase in the number of branch points and appendages up to about postnatal day 12 after which the numbers were rapidly reduced over the next two weeks. Similarly, appendage numbers significantly increased over the first two weeks until postnatal day 17 and then fell to near adult levels by postnatal day 34. The majority of branch points and appendages occur within 100-200 microm of the soma (10-30% of the dendritic diameter). The data indicate that perigeniculate nucleus dendritic maturation lags shortly behind that of the retina but may precede that of its dorsal thalamic target, the lateral geniculate nucleus. Thus, it may be that the earlier maturation of the perigeniculate nucleus and its inhibitory input is a necessary requirement for the proper development of retinogeniculate and corticothalamic topographic maps within the dorsal lateral geniculate nucleus and perigeniculate nucleus.     

Why is the hyperplastic polyp a marker for the precancerous condition of the gastric mucosa?

It is well known from the older literature that gastric carcinomas are more likely to develop in a stomach containing hyperplastic polyps. The reason why such a stomach should represent a precancerous condition is, however, largely unexplained. The aim of this study was to determine the disorders of the gastric mucosa in which hyperplastic polyps occur. In 244 patients with hyperplastic polyp, in whom at least two additional biopsies each from the antrum and corpus were available, gastritis was classified on the basis of the updated Sydney System. In none of the 244 patients was the gastric mucosa found to be normal. The most common disorder, at 51.3%, was autoimmune gastritis of the corpus mucosa, while chronic active Helicobacter pylori (Hp) gastritis was seen in 37.3% of the patients. Of the patients with Hp gastritis, 56.1% had corpus-dominant Hp gastritis. Other forms were relatively rare: when A-gastritis, corpus-dominant Hp gastritis and any other form of Hp gastritis were lumped together as a precancerous condition, these changes were found in 88.6% of the patients with hyperplastic polyps of the stomach. In the presence of hyperplastic polyps of the gastric mucosa, additional biopsies obtained from the antrum and corpus should always be performed to obtain a basis for deciding whether to apply Hp eradication treatment as potential carcinoma prophylaxis.     

Exercise and the immune system: a model of the stress response?

Exercise influences natural immunity, T- and B-cell functions, and cytokine responses, through circulatory (hemodynamic) changes and by endocrine hormones secreted in response to physical stress. The magnitude of the effects on the immune system reflects the intensity, duration and chronicity of the exercise. In this review, Laurie Hoffman-Goetz and Bente KlarlundPedersen suggest that exercise-immune interactions can be viewed as a subset of stress immunology.     

Does the physician order-entry system increase the revenue of a general hospital?

OBJECTIVE: The purpose of this study was to examine whether the physician order-entry system (POE) could increase the outpatient and inpatient revenue of hospitals. METHOD: We analyzed the inpatient and outpatient revenue data of all general hospitals (212) in South Korea obtained from the Korean National Health Insurance Corporation (KNHIC) during the period from 1996 to 1999 using the mixed model for repeated measure data. RESULTS: Analysis of the 4-years' panel data showed that both outpatient and inpatient revenues increased significantly after POE introduction. The hospital characteristics significantly influencing inpatient revenue were the number of beds, number of physicians and the tertiary status of a hospital; whereas those for outpatient revenue were the number of beds, number of physicians, the private status of a hospital, the tertiary status of a hospital and the urban status of a hospital. CONCLUSION: The revenues from both outpatients and inpatients were found to be increased after the introduction of the POE, while controlling for population size, competition, income, hospital location, hospital size, tertiary status and public status.