Placental transport of immunoglobulin G.

Autism spectrum disorders (ASDs) are common and clinically heterogeneous neurodevelopmental disorders. Gastrointestinal disorders and associated symptoms are commonly reported in individuals with ASDs, but key issues such as the prevalence and best treatment of these conditions are incompletely understood. A central difficulty in recognizing and characterizing gastrointestinal dysfunction with ASDs is the communication difficulties experienced by many affected individuals. A multidisciplinary panel reviewed the medical literature with the aim of generating evidence-based recommendations for diagnostic evaluation and management of gastrointestinal problems in this patient population. The panel concluded that evidence-based recommendations are not yet available. The consensus expert opinion of the panel was that individuals with ASDs deserve the same thoroughness and standard of care in the diagnostic workup and treatment of gastrointestinal concerns as should occur for patients without ASDs. Care providers should be aware that problem behavior in patients with ASDs may be the primary or sole symptom of the underlying medical condition, including some gastrointestinal disorders. For these patients, integration of behavioral and medical care may be most beneficial. Priorities for future research are identified to advance our understanding and management of gastrointestinal disorders in persons with ASDs.

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Evaluation, Diagnosis, and Treatment of Gastrointestinal Disorders in Individuals With ASDs: A Consensus Report

The recent association between Zika virus (ZIKV) infection during pregnancy and fetal microcephaly has led to a renewed interest in the mechanisms by which vertically transmitted microorganisms reach the fetus and cause congenital disease. In this Opinion article, we provide an overview of the structure and cellular composition of the human placenta and of the mechanisms by which traditional 'TORCH' pathogens (Toxoplasma gondii, other, rubella virus, cytomegalovirus and herpes simplex virus) access the fetal compartment. Based on our current understanding of ZIKV pathogenesis and the developmental defects that are caused by fetal ZIKV infection, ZIKV should be considered a TORCH pathogen and future research and public health measures should be planned and implemented accordingly.

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Zika virus - reigniting the TORCH.

Microbial Vertical Transmission During Human Pregnancy

Importance Biological data are lacking with respect to risk of vertical transmission and mechanisms of fetoplacental protection in maternal severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Objective To quantify SARS-CoV-2 viral load in maternal and neonatal biofluids, transplacental passage of anti–SARS-CoV-2 antibody, and incidence of fetoplacental infection. Design, Setting, and Participants This cohort study was conducted among pregnant women presenting for care at 3 tertiary care centers in Boston, Massachusetts. Women with reverse transcription–polymerase chain reaction (RT-PCR) results positive for SARS-CoV-2 were recruited from April 2 to June 13, 2020, and follow-up occurred through July 10, 2020. Contemporaneous participants without SARS-CoV-2 infection were enrolled as a convenience sample from pregnant women with RT-PCR results negative for SARS-CoV-2. Exposures SARS-CoV-2 infection in pregnancy, defined by nasopharyngeal swab RT-PCR. Main Outcomes and Measures The main outcomes were SARS-CoV-2 viral load in maternal plasma or respiratory fluids and umbilical cord plasma, quantification of anti–SARS-CoV-2 antibodies in maternal and cord plasma, and presence of SARS-CoV-2 RNA in the placenta. Results Among 127 pregnant women enrolled, 64 with RT-PCR results positive for SARS-CoV-2 (mean [SD] age, 31.6 [5.6] years) and 63 with RT-PCR results negative for SARS-CoV-2 (mean [SD] age, 33.9 [5.4] years) provided samples for analysis. Of women with SARS-CoV-2 infection, 23 (36%) were asymptomatic, 22 (34%) had mild disease, 7 (11%) had moderate disease, 10 (16%) had severe disease, and 2 (3%) had critical disease. In viral load analyses among 107 women, there was no detectable viremia in maternal or cord blood and no evidence of vertical transmission. Among 77 neonates tested in whom SARS-CoV-2 antibodies were quantified in cord blood, 1 had detectable immunoglobuilin M to nucleocapsid. Among 88 placentas tested, SARS-CoV-2 RNA was not detected in any. In antibody analyses among 37 women with SARS-CoV-2 infection, anti–receptor binding domain immunoglobin G was detected in 24 women (65%) and anti-nucleocapsid was detected in 26 women (70%). Mother-to-neonate transfer of anti–SARS-CoV-2 antibodies was significantly lower than transfer of anti-influenza hemagglutinin A antibodies (mean [SD] cord-to-maternal ratio: anti–receptor binding domain immunoglobin G, 0.72 [0.57]; anti-nucleocapsid, 0.74 [0.44]; anti-influenza, 1.44 [0.80];P  Conclusions and Relevance In this cohort study, there was no evidence of placental infection or definitive vertical transmission of SARS-CoV-2. Transplacental transfer of anti-SARS-CoV-2 antibodies was inefficient. Lack of viremia and reduced coexpression and colocalization of placental angiotensin-converting enzyme 2 and transmembrane serine protease 2 may serve as protective mechanisms against vertical transmission.

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Assessment of Maternal and Neonatal SARS-CoV-2 Viral Load, Transplacental Antibody Transfer, and Placental Pathology in Pregnancies During the COVID-19 Pandemic.

The concentrations in cord blood of total immunoglobulin G (IgG) and the four subclasses of IgG were measured in 34 fetuses at a mean gestational age of 25 weeks (range, 18 to 35 weeks). The blood samples were obtained by percutaneous umbilical blood sampling, and results were compared with the respective IgG subclass concentrations of the mothers. The efficiency of transplacental transfer of the different IgG subclasses was determined. Transfer of IgG1 and IgG4 was found to be significantly more efficient than that of IgG3 and IgG2. IgG2 was the subclass least efficiently transferred from mother to fetus. These differences may partly explain the susceptibility of newborns to various pathogens, such as streptococcus group B.

https://cvi.asm.org/content/cdli/1/6/667.full.pdf

Placental transfer of immunoglobulin G subclasses.

Patients with glycogen storage disease type 1B present the clinical features of glycogen storage disease type 1A. In addition, they are susceptible to recurrent bacterial infection and have recurrent oral ulcers and occasionally Crohn's-like disease. There features are due to immune dysfunction caused by a combination of neutropenia and impaired phagocytic functions.

B Z Garty

Papers

Placental transfer of immunoglobulin G subclasses.

Immune deficiency in glycogen storage disease type 1B.