Site-specific pathophysiology in a neonatal mouse model of gastroparesis

BACKGROUND

Early-life events impact maturation of the gut microbiome, enteric nervous system, and gastrointestinal motility. We examined three regions of gastric tissue to determine how maternal separation and gut microbes influence the structure and motor function of specific regions of the neonatal mouse stomach.

METHODS

Germ-free and conventionally housed C57BL/6J mouse pups underwent timed maternal separation (TmSep) or nursed uninterrupted (controls) until 14 days of life. We assessed gastric emptying by quantifying the progression of gavaged fluorescein isothiocyanate (FITC)-dextran. With isolated rings of forestomach, corpus, and antrum, we measured tone and contractility by force transduction, gastric wall thickness by light microscopy, and myenteric plexus neurochemistry by whole-mount immunostaining.

KEY RESULTS

Regional gastric sampling revealed site-specific differences in contractile patterns and myenteric plexus structure. In neonatal mice, TmSep prolonged gastric emptying. In the forestomach, TmSep increased contractile responses to carbachol, decreased muscularis externa and mucosa thickness, and increased the relative proportion of myenteric plexus nNOS+ neurons. Germ-free conditions did not appreciably alter the structure or function of the neonatal mouse stomach and did not impact the changes caused by TmSep.

CONCLUSIONS AND INFERENCES

A regional sampling approach facilitates site-specific investigations of murine gastric motor physiology and histology to identify site-specific alterations that may impact gastrointestinal function. Delayed gastric emptying in TmSep is associated with a thinner muscle wall, exaggerated cholinergic contractile responses, and increased proportions of inhibitory myenteric plexus nNOS+ neurons in the forestomach. Gut microbes do not profoundly affect the development of the neonatal mouse stomach or the gastric pathophysiology that results from TmSep.

Clostridioides difficile Infection in Hospitalized Pediatric Patients: Comparisons of Epidemiology, Testing, and Treatment from 2013 to 2019

OBJECTIVES

To compare the incidence, epidemiology, testing patterns, treatment, and outcomes of Clostridioides difficile infection (CDI) among hospitalized pediatric patients from 2013 to 2019.

STUDY DESIGN

The Pediatric Health Information System database was queried for patient admissions (age 0-17 years) with International Classification of Diseases, 9th and 10th edition, codes for diagnoses of CDI with a billing code for a CDI-related antibiotic treatment.

RESULTS

We identified 17 142 pediatric patients, representing 23 052 admissions, with CDI. The adjusted annual CDI incidence decreased over the study period from 7.09 cases per 10 000 patient-days (95% CI, 6.15-8.18) in 2013 to 4.89 cases per 10 000 patient-days (95% CI, 4.03-5.93) in 2019 (P < .001). C difficile-specific testing also decreased during the study period (P < .001). Chronic gastrointestinal conditions (36%) and malignancy (32%) were the most common comorbidities in CDI encounters. Oral metronidazole use decreased during the study period (P < .01) and oral vancomycin use increased (P < .001).

CONCLUSIONS

Our study demonstrates a decrease in CDI incidence in hospitalized pediatric patients, a notable change from prior studies, although this may have been influenced by altered testing patterns. We found a high incidence of CDI in patients with cancer and gastrointestinal conditions: groups that warrant targeted evaluation of CDI prevention and treatment.

Early-life malnutrition causes gastrointestinal dysmotility that is sexually dimorphic

BACKGROUND

Slow gastrointestinal (GI) transit occurs in moderate-to-severe malnutrition. Mechanisms underlying malnutrition-associated dysmotility remain unknown, partially due to lack of animal models. This study sought to characterize GI dysmotility in mouse models of malnutrition.

METHODS

Neonatal mice were malnourished by timed maternal separation. Alternatively, low-protein, low-fat diet was administered to dams, with malnourished neonates tested at two weeks or weaned to the same chow and tested as young adults. We determined total GI transit time by carmine red gavage, colonic motility by rectal bead latency, and both gastric emptying and small bowel motility with fluorescein isothiocyanate-conjugated dextran. We assessed histology with light microscopy, ex vivo contractility and permeability with force-transduction and Ussing chamber studies, and gut microbiota composition by 16S rDNA sequencing.

KEY RESULTS

Both models of neonatal malnutrition and young adult malnourished males but not females exhibited moderate growth faltering, stunting, and grossly abnormal stomachs. Progression of fluorescent dye was impaired in both neonatal models of malnutrition, whereas gastric emptying was delayed only in maternally separated pups and malnourished young adult females. Malnourished young adult males but not females had atrophic GI mucosa, exaggerated intestinal contractile responses, and increased gut barrier permeability. These sex-specific abnormalities were associated with altered gut microbial communities.

CONCLUSIONS & INFERENCES

Multiple models of early-life malnutrition exhibit delayed upper GI transit. Malnutrition affects young adult males more profoundly than females. These models will facilitate future studies to identify mechanisms underlying malnutrition-induced pathophysiology and sex-specific regulatory effects.

Microbiota on biotics: probiotics, prebiotics, and synbiotics to optimize growth and metabolism

The early stages of the metagenomics era produced countless observational studies linking various human diseases to alterations in the gut microbiota. Only recently have we begun to decipher the causal roles that gut microbes play in many of these conditions. Despite an incomplete understanding of how gut microbes influence pathophysiology, clinical trials have tested empirically numerous microbiota-targeting therapies to prevent or treat disease. Unsurprisingly, these trials have yielded mixed results. Nonetheless, the consumer market for probiotics, prebiotics, and synbiotics continues to grow. This theme paper highlights recent discoveries of mechanisms underlying diet-microbial-host interactions as they pertain to growth and metabolism and discusses current and future applications of microbiota-targeting therapies in the context of child malnutrition as well as obesity and its metabolic comorbidities, including nonalcoholic fatty liver disease and cardiovascular disease. We also highlight current challenges and identify future directions to facilitate a more efficient and direct path to clinical impact.

Streptococcal meningitis in pigs: results of a five-year survey

Information about new outbreaks of streptococcal meningitis in pigs has been collected since the disease was first recognised in the United Kingdom in late 1973. The apparent spread of the disease across the country is illustrated. Factors affecting the age distribution of the disease and the dissemination of the infection are also discussed.

Serological response in mares affected by contagious equine metritis 1977

A serum agglutination and antiglobulin test is described for the detection of antibodies to the contagious equine metritis organism. A provisional interpretation of the test is proposed and using this interpretation the results of 66 such tests are discussed.