BackgroundAntibodies of the IgG3 subclass have been implicated in the pathogenesis of the spontaneous glomerulonephritis observed in mice of the MRL/MpJ-Tnfrsf6lpr (MRL/lpr) inbred strain which have been widely studied as a model of systemic lupus erythematosus We have produced IgG3-deficient (-/-) mice with the MRL/lpr genetic background to determine whether IgG3 antibodies are necessary for or at least contributory to MRL/lpr-associated nephritis.ResultsThe gamma3 genotype (+/+ vs. +/- vs. -/-) did not appear to significantly affect serum titers of IgG auto-antibodies specific for double-stranded DNA (dsDNA) or α-actinin. However, while substantial serum titers of IgG3 auto-antibodies specific for double-stranded DNA (dsDNA) or α-actinin were seen in gamma3 +/+ mice, somewhat lower serum titers of these IgG3 auto-antibodies were found in gamma3 +/- mice, and gamma3 -/- mice exhibited baseline concentrations of these auto-antibodies. Analysis of immunoglobulins eluted from snap-frozen kidneys obtained from mice of all three gamma3 genotypes at ~18 weeks of age revealed much higher quantities of IgG in the kidneys from gamma3 +/+ than gamma3 -/- mice, and most IgG eluted from +/+ mice was IgG3. The serum creatinine levels in gamma3 +/+ mice substantially exceeded those of age-matched gamma3 -/- mice after ~21 weeks of age. Histopathological examination of kidneys from mice sacrificed at pre-determined ages also revealed more extensive glomerulosclerosis in gamma3 +/+ or +/- mice than in -/- mice beginning at 21 weeks of age. Survival analysis for IgG3-deficient and IgG3-producing MRL/lpr mice revealed that gamma3 -/- mice lived significantly longer (p = 0.0006) than either gamma3 +/- or +/+ mice. Spontaneous death appeared to be due to irreversible renal failure, because > 85% of glomeruli in kidneys from mice that died spontaneously were obliterated by glomerulosclerosis.ConclusionsThe available evidence suggests that IgG3 deficiency partially protects MRL/lpr mice against glomerulonephritis-associated morbidity and mortality by slowing or arresting the progression to glomerulosclerosis.ReviewersThis article was reviewed by Pushpa Pandiyan, Irun Cohen, and Etienne Joly.

Bariatric surgery is a major risk factor for bezoar formation secondary to decreased gastric motility, gastric acidity, and pyloric function.1 This case is about a 49-year-old female veteran, 3 weeks status-post Roux-en-Y gastric bypass surgery, who presented with acute abdominal pain and oral intolerance. After being diagnosed with a bezoar and esophagogastroduodenoscopic removal, the patient had immediate relief of symptoms. Unfortunately, over the course of 4 months, this patient experienced three recurrent episodes of bezoar formation (with a possible fourth episode that could not be confirmed secondary to resolution of symptoms after administration of oral contrast load). Based on her dietary history and gross appearance of the bezoar, the patient was determined to have developed recurrent lactobezoars. Lactobezoars are composed of milk and mucous proteins and are commonly found in neonates with immature gastrointestinal tracts.7 This unusual complication demonstrates how current dietary recommendations encouraging dairy consumption to meet daily protein requirements may have increased this patient’s risk for lactobezoar formation. This case illustrates the importance of balancing the risks and benefits of macronutrient requirements after bariatric surgery with postsurgical bezoar complications.

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Aquatic board sports, particularly traditional surfing, kitesurfing, skimboarding, stand-up paddleboarding, and foil surfing, are growing in popularity. Increased participation has revealed similar injury types, mechanisms, and unique patterns related to the individual board sports. Practitioners who live near aquatic environments should familiarize themselves with these injury patterns to provide high-quality care and prevention for participating individuals. This article will examine the current literature for each aquatic board sport and summarize specific injury-type data to provide better guidance to clinicians.