Microbiome subcommunity learning with logistic-tree normal latent Dirichlet allocation.

Mixed-membership (MM) models such as latent Dirichlet allocation (LDA) have been applied to microbiome compositional data to identify latent subcommunities of microbial species. These subcommunities are informative for understanding the biological interplay of microbes and for predicting health outcomes. However, microbiome compositions typically display substantial cross-sample heterogeneities in subcommunity compositions-that is, the variability in the proportions of microbes in shared subcommunities across samples-which is not accounted for in prior analyses. As a result, LDA can produce inference, which is highly sensitive to the specification of the number of subcommunities and often divides a single subcommunity into multiple artificial ones. To address this limitation, we incorporate the logistic-tree normal (LTN) model into LDA to form a new MM model. This model allows cross-sample variation in the composition of each subcommunity around some "centroid" composition that defines the subcommunity. Incorporation of auxiliary Pólya-Gamma variables enables a computationally efficient collapsed blocked Gibbs sampler to carry out Bayesian inference under this model. By accounting for such heterogeneity, our new model restores the robustness of the inference in the specification of the number of subcommunities and allows meaningful subcommunities to be identified.

Fetal Gallstones in a Newborn after Maternal COVID-19 Infection.

Fetal gallstones are rare incidental findings on ultrasound during pregnancy. We describe a newborn girl with gallstones that was born to a mother who had COVID-19 infection during her last trimester. The baby remained asymptomatic, and the stones resolved spontaneously without any treatment or complications within six weeks of birth. Several conditions predispose to fetal gallstones, and it is unclear if the recent maternal COVID-19 infection had any role in the occurrence of these abnormalities or was merely coincidental. This is the first case describing an association of fetal gallstones with a COVID-19 infection in pregnancy.

Duodenal web associated with malrotation and review of literature.

Intestinal obstruction due to midgut malrotation in neonates is well known. The incidence of malrotation in newborns is around 1:500 and the symptomatic incidence is 1:6000 births. Duodenal web as a cause of intestinal obstruction is less common and is reported to be 1:10 000-1:40 000. Malrotation is known to be associated with other congenital obstructive anomalies including duodenal atresia, stenosis and duodenal web. But, intestinal obstruction due to malrotation associated with duodenal web has been reported only rarely with a few published cases in our literature review. We present a case of intestinal obstruction diagnosed in the prenatal period via sonogram. A plain X-ray of the abdomen after birth showed a distended duodenum with paucity of air distally suggesting duodenal obstruction. An exploratory laparotomy showed a duodenal web proximal to the sphincter of oddi. The patient also had an associated malrotation and underwent Ladd's procedure and appendectomy. The post-operative period was uneventful.

A preterm infant with semilobar holoprosencephaly and hydrocephalus: a case report.

INTRODUCTION: Holoprosencephaly (HPE) is a rare presentation in newborns. It refers to an incomplete or absent division of the prosencephalon or forebrain into distinct cerebral hemispheres. CASE PRESENTATION: A preterm baby girl, first of dizygotic twins, born at 26 weeks of gestation to a 45 year old mother, was prenatally diagnosed with ventriculomegaly on fetal ultrasonogram. At birth the baby had frontal bossing with sun setting eyes and a full anterior fontanel. Initial head ultra-sonography (HUS) showed ventriculomegaly and semilobar holoprosencephaly, which was confirmed by computed tomography scan. Subsequently, the baby developed hydrocephalus that progressively increased. Eventually, the cerebrospinal fluid required drainage and a ventriculo-peritoneal shunt was placed. CONCLUSION: Holoprosencephaly has heterogeneous etiologies, including teratogenic and or a genetic basis. It is prudent to diagnose holoprosencephaly prenatally and determine the type to classify severity, complications and survival rate. It is also important to recognize that even with monozygotic twins only one twin may have HPE. The parents of a baby diagnosed with holoprosencephaly should be counseled about the poor prognosis.