Evaluation of plasma IL-21 as a potential biomarker for type 1 diabetes progression

IL-21 is a multifunctional cytokine linked with the pathophysiology of several autoimmune diseases, including type 1 diabetes. In this study, our aim was to examine plasma IL-21 levels in individuals at different stages of type 1 diabetes progression. We measured plasma IL-21 levels, as well as levels of other key pro-inflammatory cytokines (IL-17A, TNF-α and IL-6), from 37 adults with established type 1 diabetes and 46 healthy age-matched adult controls, as well as from 53 children with newly diagnosed type 1 diabetes, 48 at-risk children positive for type 1 diabetes-associated autoantibodies and 123 healthy age-matched pediatric controls using the ultrasensitive Quanterix SiMoA technology. Adults with established type 1 diabetes had higher plasma IL-21 levels compared to healthy controls. However, the plasma IL-21 levels showed no statistically significant correlation with clinical variables, such as BMI, C-peptide, HbA1c, or hsCRP levels, evaluated in parallel. In children, plasma IL-21 levels were almost ten times higher than in adults. However, no significant differences in plasma IL-21 levels were detected between healthy children, autoantibody-positive at-risk children, and children with newly diagnosed type 1 diabetes. In conclusion, plasma IL-21 levels in adults with established type 1 diabetes were increased, which may be associated with autoimmunity. The physiologically high plasma IL-21 levels in children may, however, reduce the potential of IL-21 as a biomarker for autoimmunity in pediatric subjects.

COVID-19 symptom relationship to antibody response and ACE2 neutralization in recovered health systems employees before and after mRNA BNT162b2 COVID-19 vaccine

Background

The humoral response to SARS-CoV-2 can provide immunity and prevent reinfection. However, less is known about how the diversity, magnitude, and length of the antibody response after a primary infection is associated with symptoms, post-infection immunity, and post-vaccinated immunity.

Methods

Cook County Health employees provided blood samples and completed an online survey 8–10 weeks after a PCR-confirmed positive SARS-CoV-2 test (pre-vaccinated, N = 41) and again, 1–4 weeks after completion of a 2-dose series mRNA BNT162b2 COVID-19 vaccine (post-vaccinated, N = 27). Associations were evaluated between SARS-CoV-2 antibody titers, participant demographics, and clinical characteristics. Antibody titers and angiotensin-converting enzyme 2 (ACE2) neutralization were compared before and after the mRNA BNT162b2 COVID-19 vaccine.

Results

Antibody titers to the spike protein (ST4), receptor binding domain (RBD), and RBD mutant D614G were significantly associated with anosmia and ageusia, cough, and fever. Spike protein antibody titers and ACE2 neutralization were significantly higher in participants that presented with these symptoms. Antibody titers to the spike protein N-terminal domain (NTD), RBD, and ST4, and ACE2 IC50 were significantly higher in all post-vaccinated participant samples compared to pre-vaccinated participant sample, and not dependent on previously reported symptoms.

Conclusions

Spike protein antibody titers and ACE2 neutralization are associated with the presentation of anosmia and ageusia, cough, and fever after SARS-CoV-2 infection. Symptom response to previous SARS-CoV-2 infection did not influence the antibody response from subsequent vaccination. These results suggest a relationship between infection severity and the magnitude of the immune response and provide meaningful insights into COVID-19 immunity according to discrete symptom presentation.

Level and Duration of IgG and Neutralizing Antibodies to SARS-CoV-2 in Children with Symptomatic or Asymptomatic SARS-CoV-2 Infection

There are conflicting data about level and duration of Abs to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in children after symptomatic or asymptomatic infection. In this human population, we enrolled adults and children in a prospective 6-mo study in the following categories: 1) symptomatic, SARS-CoV-2 PCR⁺ (SP⁺; children, n = 8; adults, n = 16), 2) symptomatic, PCR^-, or untested (children, n = 27), 3) asymptomatic exposed (children, n = 13), and 4) asymptomatic, no known exposure (children, n = 19). Neutralizing Abs (nAbs) and IgG Abs to SARS-CoV-2 Ags and spike protein variants were measured by multiplex serological assay. All SP⁺ children developed nAb, whereas 81% of SP⁺ adults developed nAb. Decline in the presence of nAb over 6 mo was not significant in symptomatic children (100 to 87.5%; p = 0.32) in contrast to adults (81.3 to 50.0%; p = 0.03). Among children with nAb (n = 22), nAb titers and change in titers over 6 mo were similar in symptomatic and asymptomatic children. In children and adults, nAb levels postinfection were 10-fold lower than those reported after SARS-CoV-2 mRNA vaccination. Levels of IgG Abs in children to SARS-CoV-2 Ags and spike protein variants were similar to those in adults. IgG levels to primary Ags decreased over time in children and adults, but levels to three spike variants decreased only in children. Children with asymptomatic or symptomatic SARS-CoV-2 infection develop nAbs that remain present longer than in adults but wane in titer over time and broad IgG Abs that also wane in level over time. However, nAb levels were lower postinfection than those reported after immunization.

The anti-SARS-CoV-2 monoclonal antibody, bamlanivimab, minimally impacts the endogenous immune response to COVID-19 vaccination

As the coronavirus disease 2019 (COVID-19) pandemic evolves and vaccine rollout progresses, the availability and demand for monoclonal antibodies for the prevention and treatment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are also accelerating. This longitudinal serological study evaluated the magnitude and potency of the endogenous antibody response to COVID-19 vaccination in participants who first received a COVID-19 monoclonal antibody in a prevention study. Over the course of six months, serum samples were collected from a population of nursing home residents and staff enrolled in a clinical trial who were randomized to either bamlanivimab treatment or placebo. In an unplanned component of this trial, a subset of these participants was subsequently fully vaccinated with two doses of either SpikeVax (Moderna) or Comirnaty (BioNTech/Pfizer) COVID-19 mRNA vaccines. This post-hoc analysis assessed the immune response to vaccination for 135 participants without prior SARS-CoV-2 infection. Antibody titers and potency were assessed using three assays against SARS-CoV-2 proteins that bamlanivimab does not efficiently bind to, thereby reflecting the endogenous antibody response. All bamlanivimab and placebo recipients mounted a robust immune response to full COVID-19 vaccination, irrespective of age, risk-category, and vaccine type with any observed differences of uncertain clinical importance. These findings are pertinent for informing public health policy with results that suggest that the benefit of receiving COVID-19 vaccination at the earliest opportunity outweighs the minimal effect on the endogenous immune response due to prior prophylactic COVID-19 monoclonal antibody infusion.

Relationship between gene expression patterns from nasopharyngeal swabs and serum biomarkers in patients hospitalized with COVID-19, following treatment with the neutralizing monoclonal antibody bamlanivimab

Background

A thorough understanding of a patient’s inflammatory response to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection is crucial to discerning the associated, underlying immunological processes and to the selection and implementation of treatment strategies. Defining peripheral blood biomarkers relevant to SARS-CoV-2 infection is fundamental to detecting and monitoring this systemic disease. This safety-focused study aims to monitor and characterize the immune response to SARS-CoV-2 infection via analysis of peripheral blood and nasopharyngeal swab samples obtained from patients hospitalized with Coronavirus disease 2019 (COVID-19), in the presence or absence of bamlanivimab treatment.

Methods

23 patients hospitalized with COVID-19 were randomized to receive a single dose of the neutralizing monoclonal antibody, bamlanivimab (700 mg, 2800 mg or 7000 mg) or placebo, at study initiation (Clinical Trial; NCT04411628). Serum samples and nasopharyngeal swabs were collected at multiple time points over 1 month. A Proximity Extension Array was used to detect inflammatory profiles from protein biomarkers in the serum of hospitalized COVID-19 patients relative to age/sex-matched healthy controls. RNA sequencing was performed on nasopharyngeal swabs. A Luminex serology assay and Elecsys® Anti-SARS-CoV-2 immunoassay were used to detect endogenous antibody formation and to monitor seroconversion in each cohort over time. A mixed model for repeated measures approach was used to analyze changes in serology and serum proteins over time.

Results

Levels of IL-6, CXCL10, CXCL11, IFNγ and MCP-3 were > fourfold higher in the serum of patients with COVID-19 versus healthy controls and linked with observations of inflammatory and viral-induced interferon response genes detected in nasopharyngeal swab samples from the same patients. While IgA and IgM titers peaked around 7 days post-dose, IgG titers remained high, even after 28 days. Changes in biomarkers over time were not significantly different between the bamlanivimab and placebo groups.

Conclusions

Similarities observed between nasopharyngeal gene expression patterns and peripheral blood biomarker profiles reveal a connection between the circulation and processes in the nasopharyngeal cavity, reinforcing the potential utility of systemic blood biomarker profiling for therapeutic monitoring of patient response. Serological antibody responses in patients correlated closely with reductions in the COVID-19 inflammatory protein biomarker signature. Bamlanivimab did not affect the biomarker dynamics in this hospitalized patient population.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03345-3.

Endogenous Antibody Responses to SARS-CoV-2 in Patients With Mild or Moderate COVID-19 Who Received Bamlanivimab Alone or Bamlanivimab and Etesevimab Together

Background

Neutralizing monoclonal antibodies (mAbs) to SARS-CoV-2 are clinically efficacious when administered early, decreasing hospitalization and mortality in patients with mild or moderate COVID-19. We investigated the effects of receiving mAbs (bamlanivimab alone and bamlanivimab and etesevimab together) after SARS-CoV-2 infection on the endogenous immune response.

Methods

Longitudinal serum samples were collected from patients with mild or moderate COVID-19 in the BLAZE-1 trial who received placebo (n=153), bamlanivimab alone [700 mg (n=100), 2800 mg (n=106), or 7000 mg (n=98)], or bamlanivimab (2800 mg) and etesevimab (2800 mg) together (n=111). A multiplex Luminex serology assay measured antibody titers against SARS-CoV-2 antigens, including SARS-CoV-2 protein variants that evade bamlanivimab or etesevimab binding, and SARS-CoV-2 pseudovirus neutralization assays were performed.

Results

The antibody response in patients who received placebo or mAbs had a broad specificity. Titer change from baseline against a receptor-binding domain mutant (Spike-RBD E484Q), as well as N-terminal domain (Spike-NTD) and nucleocapsid protein (NCP) epitopes were 1.4 to 4.1 fold lower at day 15-85 in mAb recipients compared with placebo. Neutralizing activity of day 29 sera from bamlanivimab monotherapy cohorts against both spike E484Q and beta variant (B.1.351) were slightly reduced compared with placebo (by a factor of 3.1, p=0.001, and 2.9, p=0.002, respectively). Early viral load correlated with the subsequent antibody titers of the native, unmodified humoral response (p<0.0001 at Day 15, 29, 60 and 85 for full-length spike).

Conclusions

Patients with mild or moderate COVID-19 treated with mAbs develop a wide breadth of antigenic responses to SARS-CoV-2. Small reductions in titers and neutralizing activity, potentially due to a decrease in viral load following mAb treatment, suggest minimal impact of mAb treatment on the endogenous immune response.

146. Intact Sense of Taste and Smell During COVID-19 Infection Is Associated with Absence of of SARS-CoV-2 Spike Protein Antibody Responses within 3 Months of Symptomatic Illness

Background

Although studies show most COVID-19 survivors have post-infection immunity against SARS-CoV-2 that could prevent re-infection, there is still a need to identify the breadth of antibody (Ab) responses associated with clinical phenotypes. We characterized Ab profiles at the estimated peak of Ab diversity among adults with recovered SARS-CoV-2 infections and determined their relationships with clinical factors.

Methods

From April-June 2020, 41 health system employees with PCR-confirmed symptomatic COVID-19 infection enrolled 8-10 weeks after symptom onset. Symptom questionnaires including baseline demographics, COVID-19 symptoms, disease severity, and disease duration were collected and plasma samples were assayed using a custom Luminex Multiplex platform (Figure 1) to measure the antibody response against 20 COVID-19 related antigens (Figure 2). Differences in Ab profile titers among different groups were tested using nonparametric t test and Benjamini-Hochberg adjustment for multiplicity. Associations were considered significant at FDR< 0.05.

Figure 1: Description of the Luminex Serology Assay

Figure 2: List of the COVID-19 Related Antigens and Controls Measured

Results

Mean age was 48 years (range 27-68), with 51% female, 37% White, 32% Black, 29% Asian, and 17% LatinX. Ab profiles (Figure 3) showed 100% cross-reactivity with related alpha and beta coronavirus, and 95% with SARS-CoV-1. 78% had Abs against SARS-CoV-2 nucleocapsid protein (NCP). However, 29% of patients had no immune response against the four spike protein epitopes. These participants also reported fewer symptoms, including no cases of anosmia/ageusia, suggesting mild illness. Anosmia/ageusia, fever, and cough associated significantly with higher Ab titers (Figure 4).

Conclusion

Broad immune responses to various SARS-CoV-2 and related antigens were found among a heterogeneous patient population. However, less than 3 months after symptom onset, protective Ab responses to SARS-CoV-2 spike proteins were not detected in nearly one-third of recovered patients, primarily with mild infection. Intact sense of smell and taste demonstrated the greatest association with loss of seroprotective SARS-CoV-2 Ab responses, which may be clinically useful to predict post-infection immunity. Next steps include comparing the magnitude of Ab responses following full series completion with mRNA vaccination among this cohort.

Disclosures

Robert Bencshop, PhD, Eli Lilly (Employee) Josh Poorbaugh, PhD, Eli Lilly (Employee) Ajay Nirula, MD/PhD, Eli Lilly (Employee, Shareholder) Lin Zhang, PhD, Eli Lilly and Company (Employee, Shareholder) Stephanie Beasley, BA, Eli Lilly (Employee)

Administration of aromatase inhibitor MPV-2213ad to blue fox vixens (Vulpes lagopus) as a model for contraception in female dogs

The interest in non-surgical approaches to contraception and fertility control in female dogs has increased in recent years. In this study the effect of an aromatase inhibitor (finrozole) was evaluated in fur production animals, farmed blue fox vixens, as a model for contraception in bitches. A total of 80 vixens were divided into 4 groups, receiving orally placebo (A) or finrozole 0.5 mg/kg (B), 3.5 mg/kg (C) or 24.5 mg/kg (D) for 21 consecutive days beginning in the pre-ovulatory period of heat. Monitoring of the vixens included clinical signs of heat, measurement of vaginal electrical resistance (VER) as well as oestradiol and progesterone concentrations in plasma. The approximate relation of the start of treatment to ovulation varied from 11 days before to one day after ovulation provided that the LH peak occurred 0.5-2 days before the VER peak and ovulation was then estimated to occur 2 days after the LH peak. Seventy vixens were artificially inseminated within 8 h after a 50 Ω decline in vaginal electrical resistance was detected. Ten vixens were not inseminated. Pregnancy was confirmed by transabdominal ultrasound examination and birth of cubs was recorded. The pregnancy rates in the groups were 89.5% (A), 81.3% (B), 55.6% (C) and 52.9% (D). The average number of live born pups in the four groups was 9.4 (A), 7.0 (B), 5.8 (C), and 3.8 (D), respectively. No deleterious effects (for instance malformations) of finrozole on pups could be verified. The administration of finrozole did not have a significant effect on oestradiol parameters and VER values in vixens. Progesterone values were significantly higher in treatment groups compared with the placebo group. The results indicate that pregnancy could be avoided by finrozole provided that doses of ≥3.5 mg/kg were used and the treatment was initiated at least four days before the day of artificial insemination. This corresponds with two to six days before ovulation provided that the LH peak occurred 0.5-2 days before the VER peak and that ovulation then occurred in average 2 days after the LH peak.

Pathogen exclusion properties of canine probiotics are influenced by the growth media and physical treatments simulating industrial processes

AIMS

Manufacturing process used in preparation of probiotic products may alter beneficial properties of probiotics. The effect of different growth media and inactivation methods on the protective properties of canine-originated probiotic bacteria against adhesion of canine enteropathogens was investigated.

METHODS AND RESULTS

Three established dog probiotics, Lactobacillus fermentum VET9A, Lactobacillus plantarum VET14A and Lactobacillus rhamnosus VET16A, and their mixture were assessed using the dog mucus pathogen exclusion model. The pathogens used were Enterococcus canis, Salmonella enterica serovar Typhimurium and Clostridium perfringens. The effect of growth media, one reflecting laboratory and the other manufacture conditions, and viability (viable and heat inactivated, 80°C per 30 min) on the pathogen exclusion properties of probiotics were characterized. Greater pathogen exclusion percentages were noted for probiotics growing in conditions reflecting manufacture when compared to laboratory (P < 0·05). Inactivation of probiotics by heat (80°C per 30 min) increased pathogen exclusion compared with their viable forms (P < 0·05).

CONCLUSIONS

Manufacturing process conditions such as growth media, incubation temperature and pretreatment methods may significantly affect the protective properties of the tested strains.

SIGNIFICANCE AND IMPACT OF THE STUDY

Growing conditions and pretreatment methods should be carefully considered when designing new probiotics to reduce the risk of common infections in dogs. The studied probiotics are promising potential feed additives for dogs.

The effect of growth media and physical treatments on the adhesion properties of canine probiotics

AIMS

The manufacturing processes have been reported to influence the properties of probiotics with potential impact on health properties. The aim was to investigate the effect of different growth media and inactivation methods on the properties of canine-originated probiotic bacteria alone and in combination mixture.

METHODS AND RESULTS

Three established dog probiotics, Lactobacillus fermentum VET9A, Lactobacillus plantarum VET14A and Lactobacillus rhamnosus VET16A, and their combination mixture were evaluated for their adhesion to dog mucus. The effect of different growth media, one reflecting laboratory and the other manufacturing conditions, and inactivation methods (95°C, 80°C and UV irradiation) on the mucus adhesion of the probiotic strains was characterized. Evaluation of dog probiotics was supported by cell visualization using transmission electron microscopy (TEM). Higher adhesion percentage was reported for probiotic strains growing in laboratory rather than in manufacturing conditions (P < 0.05). Inactivation by heat (95°C, 80°C) decreased the adhesion properties when strains were cultivated in soy-based growth media compared with those grown in MRS broth (P < 0.05). TEM observations uncovered differences in cell-surface components in nonviable forms of probiotic strains as compared with their viable forms.

CONCLUSIONS

Manufacturing process conditions such as growth media and pretreatment methods may significantly affect the adhesive ability of the tested strains.

SIGNIFICANCE AND IMPACT OF THE STUDY

Growth conditions, growth media, pretreatment methods and different probiotic combinations should be carefully considered for quality control of existing probiotics and for identification of new probiotics for dogs. These may also have an impact on health benefits for the host.

Excitatory amino acid transporter 5 is widely expressed in peripheral tissues

It is routinely stated in the literature that Excitatory Amino Acid Transporter 5 (EAAT5) is a retina-specific glutamate transporter. EAAT5 is expressed by retinal photoreceptors and bipolar cells, where it serves as a slow transporter and as an inhibitory glutamate receptor, the latter role is due to the gating of a large chloride conductance. The dogma of an exclusively retinal distribution has arisen because Northern blot analyses have previously shown only modest hybridisation in non-retinal tissues. Others have re-interpreted this as indicating that EAAT5 was only present in retinal tissues. However, this view appears to be erroneous; recent evidence demonstrating abundant expression of EAAT5 in rat testis prompted us to re-examine this dogma. A new antibody was developed to an intracellular loop region of rat EAAT5. This new tool, in concert with RT-PCR and sequencing, demonstrated that EAAT5 is widely distributed at the mRNA and protein levels in many non-nervous tissues including liver, kidney, intestine, heart, lung, and skeletal muscle. We conclude that EAAT5 is a widely distributed protein. Whether it functions in all locations as a glutamate transporter, or mainly as a glutamate-gated chloride conductance, remains to be determined.

Intussusception and rotavirus associated hospitalisation in New Zealand

AIMS

To describe the epidemiology of intussusception and its relation to rotavirus associated hospitalisation in New Zealand.

METHODS

National hospital discharge data between January 1998 and June 2003 for all children younger than 3 years of age with intussusception were reviewed. Independently, children from the same age group, admitted to eight paediatric units with rotavirus gastroenteritis between May 1998 and May 2000, were identified prospectively. Epidemiological characteristics of cases with intussusception were compared with those of hospitalised rotavirus disease.

RESULTS

During the 5.5 year study period, there were 277 cases of intussusception and no deaths. Most (72%) occurred in the first year of life (age adjusted incident rate 65 per 100,000 child-years, 95% CI 56 to 74). Risk of intussusception was less in females (risk ratio 0.58; 95% CI 0.43 to 0.78) and for Maori (risk ratio 0.52; 95% CI 0.35 to 0.77) when compared with European infants. In contrast to hospitalised rotavirus cases, intussusception peaked at a younger age and lacked seasonality.

CONCLUSIONS

This study provides national baseline data on intussusception for future rotavirus vaccine programmes in New Zealand. Wild-type rotaviruses do not appear to have a major role in triggering intussusception. Prospective surveillance systems, using standardised case definitions and nested case-control methodology, are needed to further our understanding of the aetiology and epidemiology of intussusception.

Fermented soymilk with a monoculture of Lactococcus lactis

Lactococcus lactis strain (LL3) isolated from mothers' milk was used to produce fermented soymilk. The strain survived at levels of over 7 log cfu/ml for 3 weeks in the fermented soymilk. A consumer survey was carried out to compare the acceptability of the fermented product with a similar product made with L. lactis ATCC11545 originally isolated from cow's milk. Blind samples produced by fermentation with the two strains were rated equally attractive, whereas information on the origin of the strains significantly enhanced the pleasantness of the fermented soymilk.

Structure of Thermotoga maritima stationary phase survival protein SurE: a novel acid phosphatase

BACKGROUND

The rpoS, nlpD, pcm, and surE genes are among many whose expression is induced during the stationary phase of bacterial growth. rpoS codes for the stationary-phase RNA polymerase sigma subunit, and nlpD codes for a lipoprotein. The pcm gene product repairs damaged proteins by converting the atypical isoaspartyl residues back to L-aspartyls. The physiological and biochemical functions of surE are unknown, but its importance in stress is supported by the duplication of the surE gene in E. coli subjected to high-temperature growth. The pcm and surE genes are highly conserved in bacteria, archaea, and plants.

RESULTS

The structure of SurE from Thermotoga maritima was determined at 2.0 A. The SurE monomer is composed of two domains; a conserved N-terminal domain, a Rossman fold, and a C-terminal oligomerization domain, a new fold. Monomers form a dimer that assembles into a tetramer. Biochemical analysis suggests that SurE is an acid phosphatase, with an optimum pH of 5.5-6.2. The active site was identified in the N-terminal domain through analysis of conserved residues. Structure-based site-directed point mutations abolished phosphatase activity. T. maritima SurE intra- and intersubunit salt bridges were identified that may explain the SurE thermostability.

CONCLUSIONS

The structure of SurE provided information about the protein's fold, oligomeric state, and active site. The protein possessed magnesium-dependent acid phosphatase activity, but the physiologically relevant substrate(s) remains to be identified. The importance of three of the assigned active site residues in catalysis was confirmed by site-directed mutagenesis.

The potential for improvement in outcome of children with intussusception in the South Island

AIMS

To review the experience in the South Island to predict the extent to which the outcome in intussusception might be expected to improve by the introduction of management guidelines and access to a regional specialist paediatric surgical service.

METHODS

Children with intussusception treated in the South Island during an eleven year period until 1998 were identified from hospital coding systems, the Southern RegionalHealth Authority and from departmental audit programmes. Details of management and outcome were analysed.

RESULTS

Data proved difficult to obtain. There were 83 children identified with intussusception confirmed on enema or at surgery; 76 had an enema that was successful in 44. Delayed repeat enema and gas enema techniques were not used as frequently as might be expected. The operative rate was higher than that reported by other centres.

CONCLUSIONS

Current data, coding and audit systems have significant short comings, which limit availability of reliable outcome data. Increased awareness of the expanded indications for enema reduction, use of air (rather than barium) and delayed repeat enemas, and access to specialist paediatric surgical involvement appears to increase the nonoperative rate. Implementation of guidelines for the management of intussusception might be expected to reduce by more than half the number of children undergoing surgery for this condition in the South Island.

The effect of neck flexion on oesophageal tension in the pig and its relevance to repaired oesophageal atresia

The indications for postoperative ventilation and paralysis with neck flexion after repair of oesophageal atresia (OA) have been controversial, mainly because of a paucity of information on oesophageal compliance and the influence of posture on anastomotic tension. This study using a pig model demonstrates that 78.8% of oesophageal lengthening occurs between full flexion and the neutral position, contributing to an increase in oesophageal length of about 9%. Compliance of the oesophagus is a linear function of the natural log of the tension applied. These data imply that any postural change (e.g., head and neck flexion) that allows the oesophagus to shorten may produce an exponential reduction in the tension and suggest that the manoeuvre may be appropriate in long-gap OA where there is considerable tension across the oesophageal anastomosis.

Clarification of the process of separation of the cloaca into rectum and urogenital sinus in the rat embryo

BACKGROUND/PURPOSE

The normal process of division of the cloaca into a rectum and urogenital tract is still not fully understood. The main controversies relate to how the urorectal septum (URS) divides the cloaca and whether the URS fuses with the cloacal membrane. This study used a 3-dimensional reconstruction technique, combined with histologic correlation, to observe the developmental and septational processes of the cloaca of the normal rat embryo from gestational days 11 to 16.

METHODS

Normal rat embryos from gestational days 11 to 16 were sectioned serially both transversely and sagittally and stained with H&E. 3-dimensional reconstructions were performed on embryos younger than day 13.5. The relevant structures were examined in a temporo-spatial sequence.

RESULTS

The tailgut started to regress by apoptosis on day 12 in a cranio-caudal direction. The URS, first evident in day-12.5 embryos, extended and fused with the cloacal membrane on day 15 of gestation, completing the separation of the cloaca into rectum and bladder. Regression of the tailgut and ventral protrusion of the urogenital sinus markedly changed the configuration of the cloaca. The cloacal membrane did not break down until after it had fused with the URS.

CONCLUSIONS

These findings clarify the relative contributions made by active septation of the cloaca by the URS and configurational changes of the cloaca to produce a rectum and bladder. The URS fuses with the cloacal membrane before the anal and urogenital membranes break down.

Oesophageal atresia in twins

The twin incidence is higher in infants with oesophageal atresia (OA) than in the general population. The purpose of this study was to review the twin OA information from five institutions and evaluate possible links between the development of OA and the twinning process. Data were compared, combined, and analysed. There was a total of 1,215 infants with OA, of whom 50 were from a twin pregnancy and 1 from a triplet pregnancy. Two sets of twins were concordant for OA. Mean birth weights and gestational ages were lower in the twin infants (P < 0.0005) and survival was lower in twins (65%, P < 0.005) than singletons. The anatomical variant of pure OA without fistula was seen in proportionally fewer twins (4%) than in singletons (7%). Multiple anomalies were present in 40% of twins compared with 33% of singletons, although this did not reach statistical significance. OA in our multicentre population was more common in twins. Several possible mechanisms are put forward to explain the apparent link between twinning and OA. Further analysis of this aspect of OA may aid in understanding the aetiology of this congenital anomaly.

Limitations of percutaneous endoscopic gastrostomy in facilitating enteral nutrition in children: review of the shortcomings of a new technique

Percutaneous endoscopic gastrostomy (PEG) insertion became the preferred technique for facilitating enteral nutrition in children unable to take adequate caloric intake orally once its advantages over the standard Stamm gastrostomy became apparent. It has taken longer for some of its limitations and shortcomings to be recognized. Problems encountered during PEG insertion include: inability to enter the stomach with the trocar, oesophageal laceration, colonic perforation, gastro-colo-cutaneous fistula, peritonitis, subcutaneous emphysema, external migration of inner flange, wound infection, peristomal excoriation, symptomatic gastro-oesophageal reflux requiring later fundoplication, intestinal obstruction and haemorrhage. Many of these complications can be avoided by attention to technique.

Congenital prepubic sinus: possible variant of dorsal urethral duplication (Stephens type 2)

We report on 3 patients with a midline sinus extending from the skin overlying the pubis to the anterior wall of the bladder. Two sinuses were lined by transitional epithelium. The sinuses were surrounded by bundles of smooth muscle and lacked any inflammatory reaction, which suggests a developmental origin. Possible etiological causes for this unusual congenital anomaly are discussed. We conclude that these sinuses may represent a variant of epispadiac duplication of the urethra.