Cell behaviors underlying Myxococcus xanthus aggregate dispersal.

IMPORTANCE: Understanding the processes behind bacterial biofilm formation, maintenance, and dispersal is essential for addressing their effects on health and ecology. Within these multicellular communities, various cues can trigger differentiation into distinct cell types, allowing cells to adapt to their specific local environment. The soil bacterium Myxococcus xanthus forms biofilms in response to starvation, marked by cells aggregating into mounds. Some aggregates persist as spore-filled fruiting bodies, while others disperse after initial formation for unknown reasons. Here, we use a combination of cell tracking analysis and computational simulations to identify behaviors at the cellular level that contribute to aggregate dispersal. Our results suggest that cells in aggregates actively determine whether to disperse or persist and undergo a transition to sporulation based on a self-produced cue related to the aggregate size. Identifying these cues is an important step in understanding and potentially manipulating bacterial cell-fate decisions.

Ultrasonography of the Explanted Uterus in Placenta Accreta Spectrum: Correlation With Intraoperative Findings and Gross Pathology.

OBJECTIVE: To better understand placenta accreta spectrum (PAS) by correlating postoperative ultrasonographic findings of the explanted uteroplacental interface with intraoperative findings and gross pathology. METHODS: We enrolled consecutive pregnant patients aged 18 years and older with a prior cesarean delivery and antenatal diagnosis of lower uterine segment PAS who planned to undergo hysterectomy into this prospective, descriptive study. All underwent cesarean hysterectomy with standardized intraoperative photography. Ultrasonography of explanted postsurgical uteruses was performed by expert radiologists to obtain standard detailed images of the myometrial-placental interface and other areas of interest. Sagittal views of the gross pathologic specimen were photographed. We correlated the intraoperative, ultrasonographic, and gross pathologic findings as a study team and report four consistent patterns that emerged from this systematic evaluation. RESULTS: Thirty-four consecutive eligible patients were enrolled. The following consistent observations emerged: 1) The uteroplacental interface in the explanted specimen was smooth and distinct. At the point of maximal placental protrusion, the myometrium was imperceptible, but the placenta was confined by a smooth thin echogenic line of uterine serosa (the scar shell) unless surgically disrupted. 2) Every specimen of PAS grade 2-3 showed placenta bulging through the lower uterine segment in the region of prior hysterotomy. 3) Placentas extended to, but not through, the uterovesical interface or scar shell. Dense adhesive disease was found between the placenta and bladder. There were no cases of true bladder invasion. 4) Placental extension beyond the serosa (invasion) has a distinct appearance on postoperative ultrasonography with irregular frond-like protrusion of placental tissue. This appearance was always the result of surgical manipulation and was not present before delivery of the neonate. CONCLUSION: These findings suggest that PAS severity is likely mediated by progressive scar dehiscence and uterine remodeling, not placental invasion. This challenges the existence of in situ invasive percreta as it is currently described.

Placental Inflammation Significantly Correlates with Reduced Risk for Retinopathy of Prematurity.

Retinopathy of prematurity (ROP), a blinding condition affecting preterm infants, is an interruption of retinal vascular maturation that is incomplete when born preterm. Although ROP demonstrates delayed onset following preterm birth, representing a window for therapeutic intervention, there are no curative or preventative measures available for this condition. The in utero environment, including placental function, is increasingly recognized for contributions to preterm infant disease risk. The current study identified a protective association between acute placental inflammation and preterm infant ROP development using logistic regression, with the most significant association found for infants without gestational exposure to maternal preeclampsia and those with earlier preterm birth. Expression analysis of proteins with described ROP risk associations demonstrated significantly decreased placental high temperature requirement A serine peptidase-1 (HTRA-1) and fatty acid binding protein 4 protein expression in infants with acute placental inflammation compared with those without. Within the postnatal peripheral circulation, HTRA-1 and vascular endothelial growth factor-A demonstrated inverse longitudinal trends for infants born in the presence of, compared with absence of, acute placental inflammation. An agnostic approach, including whole transcriptome and differential methylation placental analysis, further identify novel mediators and pathways that may underly protection. Taken together, these data build on emerging literature showing a protective association between acute placental inflammation and ROP development and identify novel mechanisms that may inform postnatal risk associations in preterm infants.

Mechanobiology as a tool for addressing the genotype-to-phenotype problem in microbiology.

The central hypothesis of the genotype-phenotype relationship is that the phenotype of a developing organism (i.e., its set of observable attributes) depends on its genome and the environment. However, as we learn more about the genetics and biochemistry of living systems, our understanding does not fully extend to the complex multiscale nature of how cells move, interact, and organize; this gap in understanding is referred to as the genotype-to-phenotype problem. The physics of soft matter sets the background on which living organisms evolved, and the cell environment is a strong determinant of cell phenotype. This inevitably leads to challenges as the full function of many genes, and the diversity of cellular behaviors cannot be assessed without wide screens of environmental conditions. Cellular mechanobiology is an emerging field that provides methodologies to understand how cells integrate chemical and physical environmental stress and signals, and how they are transduced to control cell function. Biofilm forming bacteria represent an attractive model because they are fast growing, genetically malleable and can display sophisticated self-organizing developmental behaviors similar to those found in higher organisms. Here, we propose mechanobiology as a new area of study in prokaryotic systems and describe its potential for unveiling new links between an organism's genome and phenome.

Quantification of Myxococcus xanthus Aggregation and Rippling Behaviors: Deep-Learning Transformation of Phase-Contrast into Fluorescence Microscopy Images.

Myxococcus xanthus bacteria are a model system for understanding pattern formation and collective cell behaviors. When starving, cells aggregate into fruiting bodies to form metabolically inert spores. During predation, cells self-organize into traveling cell-density waves termed ripples. Both phase-contrast and fluorescence microscopy are used to observe these patterns but each has its limitations. Phase-contrast images have higher contrast, but the resulting image intensities lose their correlation with cell density. The intensities of fluorescence microscopy images, on the other hand, are well-correlated with cell density, enabling better segmentation of aggregates and better visualization of streaming patterns in between aggregates; however, fluorescence microscopy requires the engineering of cells to express fluorescent proteins and can be phototoxic to cells. To combine the advantages of both imaging methodologies, we develop a generative adversarial network that converts phase-contrast into synthesized fluorescent images. By including an additional histogram-equalized output to the state-of-the-art pix2pixHD algorithm, our model generates accurate images of aggregates and streams, enabling the estimation of aggregate positions and sizes, but with small shifts of their boundaries. Further training on ripple patterns enables accurate estimation of the rippling wavelength. Our methods are thus applicable for many other phenotypic behaviors and pattern formation studies.

High-Rate Anisotropic Properties in Human Infant Parietal and Occipital Bone.

Computational models of infant head impact are limited by the paucity of infant cranial bone material property data, particularly with regard to the anisotropic relationships created by the trabecular fibers in infant bone. We previously reported high-rate material property data for human infant cranial bone tested perpendicular to trabeculae fiber orientation. In this study, we measure the anisotropic properties of human infant cranial bone by analyzing bending modulus parallel to the trabeculae fibers. We tested human bone specimens from nine donors ranging in age from 32 weeks gestational age to 10 months at strain rates of 12.3-30.1 s-1. Bending modulus significantly increased with donor age (p=0.008) and was 13.4 times greater along the fiber direction compared to perpendicular to the fibers. Ultimate stress was greater by 5.1 times when tested parallel to the fibers compared to perpendicular (p=0.067). Parietal bone had a higher modulus and ultimate stress compared to occipital bone, but this trend was not significant, as previously shown perpendicular to fiber orientation. Combined, these data suggest that the pediatric skull is highly age-dependent, anisotropic, and regionally dependent. The incorporation of these characteristics in finite element models of infant head impact will be necessary to advance pediatric head injury research and further our understanding of the mechanisms of head injury in children.

Fifty Years of Radiopharmaceuticals.

To celebrate the 50th anniversary of the founding of the SNMMI Technologist Section in 1970, the Radiopharmaceutical Sciences Council board of directors is pleased to contribute to this celebratory supplement of the Journal of Nuclear Medicine Technology with a perspective highlighting major developments in the radiopharmaceutical sciences that have occurred in the last 50 years.

Placenta Accreta Spectrum Disorder: Uterine Dehiscence, Not Placental Invasion.

For decades, placenta accreta spectrum disorder has been classified, staged, and described as a disorder of placental invasion. In this commentary, we argue that placenta accreta spectrum exists as a disorder of defective decidua and uterine scar dehiscence, not as a disorder of destructive trophoblast invasion. Adopting this understanding of placenta accreta spectrum will help direct research efforts and clinical resources toward the prevention, accurate diagnosis, and safe treatment of this devastating-and increasingly common-disorder.

Maternal Tobacco Smoke Exposure Causes Sex-Divergent Changes in Placental Lipid Metabolism in the Rat.

Maternal tobacco smoke exposure (MTS) affects fetal acquisition of long-chain polyunsaturated fatty acids (LCPUFA) and increases the risk of obesity and cardio-metabolic disease in the offspring. Alterations in fetal LCPUFA acquisition in maternal smoking are mediated by the placenta. The handling of LCPUFA by the placenta involves protein-mediated transfer and storage. Molecular mediators of placental LCPUFA handling include PPARγ and the fatty acid transport proteins. We previously demonstrated, in a rat model, that MTS results in programming of adult-onset obesity and metabolic disease in male, but not female, offspring. In this study, we test the hypothesis that in utero MTS exposure alters placental structure, placental LCPUFA handling, and fetal fatty acid levels, in a sex-divergent manner. We exposed pregnant rats to tobacco smoke from embryonic day 11 to term gestation. We measured placental and fetal fatty acid profiles, the systolic/diastolic ratio (SD ratio), placental histology, and expression of molecular mediators in the placenta. Our primary finding is that MTS alters fatty acid profiles in male, but not female fetuses and placenta, including increasing the ratio of omega-6 to omega-3 fatty acids. MTS also increased SD ratio in male, but not female placenta. In contrast, the expression of PPARγ and FATPs was upregulated in female, but not male placenta. We conclude that MTS causes sex-divergent changes in placental handling of LCPUFA in the rat. We speculate that our results demonstrate an adaptive response to MTS by the female placenta.

Non-Immune Hydrops, Hypotonia, Encephalopathy, and Liver Failure with Novel Compound Heterozygous AHCY Mutations.

A late-preterm infant with a prenatal diagnosis of non-immune hydrops was born with hypotonia, poor respiratory effort, chylothorax, encephalopathy, coagulopathy, progressive hepatic failure, and refractory pulmonary hypertension. Life support was withdrawn at 7 days of life due to multisystem organ failure. Rapid whole exome sequencing revealed novel compound heterozygous mutations in the gene encoding S-adenosylhomocysteine hydrolase (AHCY); each novel variant was carried by an asymptomatic parent. Reports of neonates with other AHCY mutations describe a pathology of varying severity. AHCY mutations should be considered when seeking an etiology for neonates with the combination of non-immune hydrops, hypotonia, encephalopathy, and liver failure.

Gestational Psittacosis Resulting in Neonatal Death Identified by Next-Generation RNA Sequencing of Postmortem, Formalin-Fixed Lung Tissue.

Psittacosis is a rare zoonosis that can cause severe disease and adverse outcomes during pregnancy. We identified a previously elusive case of psittacosis causing premature delivery and infant death by next-generation RNA sequencing of postmortem tissues. Hypothesis-free pathogen detection in postmortem specimens can increase the yield of epidemiologic and cause-of-death studies.

Fellowship training in pediatric pathology: a guide for program directors.

ABSTRACT The Accreditation Council for Graduate Medical Education (ACGME) has provided guidance for specialty and subspecialty fellowship training programs by defining 6 core competencies that must be met. Furthermore, the ACGME has defined several program requirements for pathology training, including those applicable to several pathology subspecialties. However, the requirements are broad and lack specific details, particularly as they pertain to the unique nature of pediatric pathology. The Fellowship Committee of the Society for Pediatric Pathology examined the ACGME requirements and interpreted the guidelines with respect to their application to training in pediatric pathology. The Committee worked within the ACGME guidelines to provide an expanded and more comprehensive set of guidelines for use by pediatric pathology fellowship directors and trainees. The resultant document lists the educational goals, core competencies, and program requirements with specific application to pediatric pathology. In addition, methods for assessing and documenting the progress of the individual trainees as they progress through each requirement are provided. It is to be emphasized that many of the guidelines set forthwith are flexible, and allowances should be made for individual differences of each training program.

A family-based paradigm to identify candidate chromosomal regions for isolated congenital diaphragmatic hernia.

Congenital diaphragmatic hernia (CDH) is a developmental defect of the diaphragm that causes high newborn mortality. Isolated or non-syndromic CDH is considered a multifactorial disease, with strong evidence implicating genetic factors. As low heritability has been reported in isolated CDH, family-based genetic methods have yet to identify the genetic factors associated with the defect. Using the Utah Population Database, we identified distantly related patients from several extended families with a high incidence of isolated CDH. Using high-density genotyping, seven patients were analyzed by homozygosity exclusion rare allele mapping (HERAM) and phased haplotype sharing (HapShare), two methods we developed to map shared chromosome regions. Our patient cohort shared three regions not previously associated with CDH, that is, 2q11.2-q12.1, 4p13 and 7q11.2, and two regions previously involved in CDH, that is, 8p23.1 and 15q26.2. The latter regions contain GATA4 and NR2F2, two genes implicated in diaphragm formation in mice. Interestingly, three patients shared the 8p23.1 locus and one of them also harbored the 15q26.2 segment. No coding variants were identified in GATA4 or NR2F2, but a rare shared variant was found in intron 1 of GATA4. This work shows the role of heritability in isolated CDH. Our family-based strategy uncovers new chromosomal regions possibly associated with disease, and suggests that non-coding variants of GATA4 and NR2F2 may contribute to the development of isolated CDH. This approach could speed up the discovery of the genes and regulatory elements causing multifactorial diseases, such as isolated CDH.

Activated NOTCH2 is overexpressed in hepatoblastomas: an immunohistochemical study.

Hepatoblastoma is a pediatric malignancy characterized by the uncontrolled proliferation of immature hepatocytes (hepatoblasts). This disease is diagnosed primarily in children younger than 5 years and is disproportionately observed in former premature infants. Cytogenetically, hepatoblastoma is characterized by numerical aberrations, as well as unbalanced translocations involving the proximal region of chromosome 1q. The NOTCH2 gene has been mapped to this locus, and it is well established that the NOTCH gene family is an important regulator of several developmental pathways. Specifically, the NOTCH2 protein is known to delay hepatoblast maturation during early hepatic organogenesis, and the reduction of NOTCH2 expression correlates with the differentiation of hepatoblasts into hepatocytes and biliary cells in the developing liver. We hypothesized that NOTCH2 is involved in the pathogenesis of hepatoblastoma by maintaining a population of undifferentiated hepatoblasts. We studied the immunohistochemical expression of NOTCH2 and its isoforms NOTCH1, NOTCH3, and NOTCH4 and the NOTCH2 primary ligand JAGGED1 in hepatoblastomas. Compared with the normal liver, an increased level of NOTCH2 expression was seen in 22 of 24 (92%) hepatoblastomas. There was no significant staining for other NOTCH isoforms and JAGGED1 in hepatoblastomas. Therefore, we suggest that NOTCH2 expression and activation, independent of JAGGED1 expression, may contribute to the pathogenesis of hepatoblastoma. In the hepatoblastoma sinusoidal vasculature, we saw NOTCH3 and NOTCH1 expression. These observations have potential implications with regard to therapeutic targeting of the NOTCH signaling pathway in hepatoblastomas.

Denys-Drash syndrome with neonatal renal failure in monozygotic twins due to c.1097G>A mutation in the WT1 gene.

Denys-Drash syndrome, characterized by nephrosis, dysgenetic gonads and a predisposition to Wilms tumor, is due to germline mutations in the WT1 gene. We report the pathologic findings on monozygotic twins, both of whom presented with male pseudohermaphroditism, nephrotic syndrome, and progressed to renal failure and death within the first month of life. Sequence analysis of WT1 demonstrated a G-to-A substitution in exon 8 of the gene (c.1097G > A), resulting in an arginine-to-histidine (R366H) substitution in the second zinc finger domain. To the best of our knowledge, this is only the second set of monozygotic twins with Denys-Drash syndrome reported to date.