Toxicity of phosphate enemas - an updated review.

INTRODUCTION: Enemas containing phosphate are widely prescribed and may cause important adverse effects. A systemic review published in 2007 reported the literature on the adverse effects of phosphate enemas from January 1957 to March 2007 and identified 12 deaths. These were thought due to electrolyte disturbances, heart failure and kidney injury. These data raised concerns about the use of phosphate enemas in routine practice. Newer osmotic-based enema alternatives are now available that do not contain absorbable ions. We sought to review the literature since this review and evaluate the latest data on the toxicity of phosphate-containing enemas. To gain a fuller picture we included case series and larger studies as well as case reports. OBJECTIVES: To review the toxicity of phosphate enemas, particularly with respect to acute metabolic consequences and their associated clinical features. To identify risk factors for metabolic toxicity and consider whether phosphate enemas should be relatively contra-indicated in specific patient groups. METHODS: A systematic literature review was conducted in PubMed, Google Scholar, and Cochrane Reviews (2005-2021) using the search terms 'phosphate enema or sodium phosphate enema' or 'phosphate-based enema' or (phosphate AND enema) or (Fleet AND enema) or 'sodium phosphate laxatives' or 'sodium phosphate catharsis' or 'sodium phosphate cathartic'. Relevant papers were read, and data were extracted. RESULTS: The searches identified 489 papers of which 25 were relevant: seven papers were case reports or small case series of metabolic abnormalities from the use of phosphate enemas in nine children, six were case reports on 16 adults. Nine papers were large case series or clinical studies that included data on systemic metabolic effects, of varying size from 24 healthy volunteers to a cohort of 70,499 patients. Case reports identified seven adult deaths but none in children. Children most often presented with decreased consciousness (6/9), and tetany (4/9). In adults overall only five cases had clinical features reported, hypotension was seen in four and QT prolongation in two. Treatment was generally symptomatic, with intravenous fluid and calcium salts for electrolyte changes and hypocalcaemia, and vasopressors for severe hypotension. Haemodialysis was used in three children and peritoneal dialysis in one, all of whom survived. In adults, haemodialysis did not prevent death in two of four cases in whom it was used. Common factors underlying toxicity were inappropriately high phosphate dose, or enema retention, both resulting in greater absorption of phosphate. Associated pre-disposing conditions included Hirschsprung disease in children and co-morbidity and renal impairment (2/5) in older adults. Absolute reported changes in serum phosphate or calcium were not accurate indicators of outcome. Larger case series and clinical trials confirm an acute effect of phosphate enemas on serum phosphate, which was related to both dose and retention time. These effects were not seen with non-phosphate preparations. In these cases series, adverse events were rarely reported. CONCLUSION: Phosphate enemas are potentially toxic, particularly in young children with Hirschsprung disease and in the elderly with co-morbidity. Raised awareness of the risk of phosphate enemas is still required. Other less toxic enema preparations are available and should be considered in patients at extremes of age. If phosphate enemas are the only clinical option careful monitoring of biochemical sequelae should be undertaken.

Autologous Transplantation of Skin-Derived Precursor Cells in a Porcine Model.

BACKGROUND: Hirschprung's disease is characterized by aganglionic bowel and often requires surgical resection. Cell-based therapies have been investigated as potential alternatives to restore functioning neurons. Skin-derived precursor cells (SKPs) differentiate into neural and glial cells in vitro and generate ganglion-like structures in rodents. In this report, we aimed to translate this approach into a large animal model of aganglionosis using autologous transplantation of SKPs. METHODS: Juvenile pigs underwent skin procurement from the shoulder and simultaneous chemical denervation of an isolated colonic segment. Skin cells were cultured in neuroglial-selective medium and labeled with fluorescent dye for later identification. The cultured SKPs were then injected into the aganglionic segments of colon, and the specimens were retrieved within seven days after transplantation. SKPs in vitro and in vivo were assessed with histologic samples for various immunofluorescent markers of multipotency and differentiation. SKPs from the time of harvest were compared to those at the time of injection using PCR. RESULTS: Prior to transplantation, 72% of SKPs stained positive for nestin and S100b, markers of neural and glial precursor cells of neural crest origin, respectively. Markers of differentiated neurons and gliocytes, TUJ1 and GFAP, were detected in 47% of cultured SKPs. After transplantation, SKPs were identified in both myenteric and submucosal plexuses of the treated colon. Nestin co-expression was detected in the SKPs within the aganglionic colon in vivo. Injected SKPs appeared to migrate and express early neuroglial differentiation markers. CONCLUSIONS: Autologous SKPs implanted into aganglionic bowel demonstrated immunophenotypes of neuroglial progenitors. Our results suggest that autologous SKPs may be potentially useful for cell-based therapy for patients with enteric nervous system disorders. TYPE OF STUDY: Basic science.

Selective serotonin reuptake inhibitors during pregnancy Do not increase the risk of Hirschsprung disease.

PURPOSE: Hirschsprung disease (HSCR) is a multifactorial disease. Maternal intake of selective serotonin reuptake inhibitors (SSRI) during early pregnancy has previously been associated with increased risk for HSCR. The aim of this study was to assess the risk for HSCR in newborns after maternal intake of SSRI in a population-based Swedish cohort. METHODS: This was a Swedish nationwide, population-based, case-control cohort study containing all children born in Sweden between 1/12006 and 31/122012. The cases were identified in the Swedish National Patient Register and the controls (five age- and sex-matched controls per case) were randomly selected among children without HSCR in the cohort. Data on maternal SSRI use during pregnancy were collected from the Swedish Prescribed Drug Register. RESULTS: Out of 775,024 born children during the study period, 150 cases of HSCR (112 males) and 750 controls (560 males) were included. Five (3.3%) mothers of newborns with HSCR had used SSRI during pregnancy compared to 16 (2.1%) mothers of the controls (p = 0.372). The mean age was similar in mothers who had used SSRI compared to those who had not (30.9 (SD +/- 5.1) versus 30.6 (SD +/- 5.0), p = 0.81). CONCLUSIONS: There was no increased risk of HSCR owing to maternal intake of SSRI in this cohort. LEVEL OF EVIDENCE: Level I.

[Expression and function of T-type α1H Ca(2)(+) channels in the rat model of Hirschsprung disease].

OBJECTIVE: To investigate the role of T-type α1H Ca(2+) channels(Cav 3.2) in the pathogenesis of Hirschsprung disease(HD). METHOD: Eighty neonatal SD rats 6 to 8 days of age were randomly divided into 2 groups, 40 in each. Microinjector catheters were carefully placed into the bowl of one group, and 0.2% benzalkonium chloride (BAC) solution was injected to establish HD rat model. Control group was treated with saline instead of benzalkonium chloride. At postoperative 4, 6 and 8 weeks, ten rats were sacrificed randomly and examined through general observation, histopathological observation and immunofluorescent staining of PGP 9.5 to identify the animal models. Meanwhile, the distribution of Cav 3.2 in abnormal colon of HD rat model was studied by immunohistochemical staining, Western blot, and the co-localization of Cav 3.2 and c-kit was studied by double immunofluorescent staining. Besides, function of Cav 3.2 was surveyed with the model rats tensile force and frequency of colonic muscle in vitro. RESULT: After 8 weeks of BAC treatment, the rat model was successfully established according to the results of histopathological and immunofluorescent staining, which showed decrease or lack of ganglion cells within the area of BAC treatment. The distribution of Cav 3.2 was detected by immunohistochemical staining. In the normal colon, Cav 3.2 were mainly distributed between circular muscle and longitudinal muscle, and showed continuous distribution. However, in the narrow segment of HD rat model, the distribution of Cav 3.2 was decreased significantly, and its continuity was destroyed . The results of Western blot were quite consistent with immunohistochemistry staining, in the narrow segment of HD rat model, the expression of Cav 3.2 was decreased gradually after the BAC treatment, especially at postoperative 8 weeks. The relative expression of Cav 3.2 of the control group was 0.63±0.06, 0.62±0.09, 0.63±0.06 at postoperative 4, 6 and 8 weeks respectively. While that of HD group was 0.63±0.06, 0.38±0.06, 0.26±0.07 respectively, which was significantly lower as compared with that of control group at postoperative 6 and 8 weeks respectively (t-value 5.27 and 8.63 respectively, both P<0.05). The co-localization of Cav 3.2 and c-kit was studied by double immunofluorescent staining. Similarly, compared with control groups, the co-localization of Cav 3.2 and c-kit were reduced obviously or vanished in the narrow segment of HD rat model. In motility studies, the control rats show cyclic depolarization regularly. However, the cyclic depolarization largely disappeared in model rats. Besides, on the premise of cyclic depolarization in control muscle strips, when we added ZnCl2, known to inhibit Cav 3.2 selectively among three T-channel isoforms, into tissue chambers, the pattern of muscle contractions appear similar to HD model rats. CONCLUSION: The abnormal alteration of Cav 3.2 probably mediate the functional change of interstitial cells of cajal in the HD, and finally induce the intestinal dysfunction of HD.

Fluorescence Visualization of the Enteric Nervous Network in a Chemically Induced Aganglionosis Model.

Gastrointestinal motility disorders, severe variants in particular, remain a therapeutic challenge in pediatric surgery. Absence of enteric ganglion cells that originate from neural crest cells is a major cause of dysmotility. However, the limitations of currently available animal models of dysmotility continue to impede the development of new therapeutics. Indeed, the short lifespan and/or poor penetrance of existing genetic models of dysmotility prohibit the functional evaluation of promising approaches, such as stem cell replacement strategy. Here, we induced an aganglionosis model using topical benzalkonium chloride in a P0-Cre/GFP transgenic mouse in which the neural crest lineage is labeled by green fluorescence. Pathological abnormalities and functional changes in the gastrointestinal tract were evaluated 2-8 weeks after chemical injury. Laparotomy combined with fluorescence microscopy allowed direct visualization of the enteric neural network in vivo. Immunohistochemical evaluation further confirmed the irreversible disappearance of ganglion cells, glial cells, and interstitial cell of Cajal. Remaining stool weight and bead expulsion time in particular supported the pathophysiological relevance of this chemically-induced model of aganglionosis. Interestingly, we show that chemical ablation of enteric ganglion cells is associated with a long lifespan. By combining genetic labeling of neural crest derivatives and chemical ablation of enteric ganglion cells, we developed a newly customized model of aganglionosis. Our results indicate that this aganglionosis model exhibits decreased gastrointestinal motility and shows sufficient survival for functional evaluation. This model may prove useful for the development of future therapies against motility disorders.

The relationship between prenatal exposure to BP-3 and Hirschsprung's disease.

Hirschsprung's disease (HSCR) is neonatal intestinal abnormality which derived from the faliure of enteric neural crest cells migration to hindgut during embryogenesis from 5 to 12 weeks. Currenly, the knowledge of environmental factors contributing to HSCR is still scarce. Benzophenone-3 (BP-3) is one of the most widely used UV filters, and has weak estrogen and strong anti-androgenic effects. In order to examine the effect of maternal BP-3 exposure on development of offspring and explore the potential mechanism, we conducted case and control study and in vitro study. In this work, BP-3 concertrations in maternal urine was detected by ultra-high performance liquid chromatography. Besides, we investigated the cytotoxicity and receptor tyrosine kinase (RET) expression in cells exposed to BP-3. The results showed that maternal BP-3 exposure was associated with offspring's HSCR in the population as well as inhibited migration of 293T and SH-SY5Y cells. What's more, we discovered dose-response relationship between RET expression and BP-3 exposure dose, and miR-218 and some other genes involved in SLIT2/ROBO1-miR-218-RET/PLAG1 pathway were also related to BP-3 exposure. Therefore, we deduced that BP-3 influenced cell migration via SLIT2/ROBO1-miR-218-RET/PLAG1 pathway. Our study firstly revealed the relationship between maternal BP-3 exposure and HSCR as well as its potential mechanism.

[Citalopram taken during pregnancy and the child born with Hirschsprung's disease]. / Citalopram indtaget under graviditet og barn født med mb. Hirschsprung

A woman treated with citalopram during the entirety of her pregnancy bore a child with Hirschsprung's disease. Theories on the development of the enteric nervous system support a possible negative effect of SSRI usage. Epidemiological studies confirm a correlation between pregnant women's use of SSRIs and congenital malformations of their children's digestive system, but not specifically Hirschsprung's disease. Certain limitations in these studies might explain this lack of specificity.

Growth failure, tardive dyskinesia, megacolon development, and hepatic damage in neonatal rats following exposure to trimethobenzamide in utero.

OBJECTIVE: Trimethobenzamide (TMB) has a pregnancy category C labeling. Tardive dyskinesia and gastrointestinal involvement in neonates were not described earlier. We aimed to investigate neurological, developmental, and hepatic effects of TMB. METHODS: Ten 10 pregnant rats were divided into two groups. During pregnancy, Group I (control) were injected with saline; Group II with TMB (5 mg/kg/day). After delivery, two experiments were planned: experiment 1 (neuro) and Experiment 2 (hepatic). Control groups contained offsprings delivered from Group I mothers: Group I-offsp-neuro (n = 15) and Group I-offsp-hepatic (n = 15). Thirty offsprings delivered from Group II mothers formed Group II-offsp-neuro (n = 15) and Group II-offsp-hepatic (n = 15). Neuro group offsprings were followed-up to observe neurological symptoms and assessed for normal growth. Hepatic group livers were excised for histological evaluation. RESULTS: The body weight between neuro groups showed significant differences (p < 0.05). In Group II-offsp-neuro low body weight, poor hair growth, tardive dyskinesia and megacolon were observed. Some alterations of liver histology were noticed in Group II-offsp-hepatic (p < 0.001). CONCLUSIONS: In utero TMB exposure may cause growth retardation, neurological damage in the developing brain and intestine, and hepatic damage. Despite recent publications reporting safety of TMB, we suggest that obstetricians and pediatricians should make a good risk-benefit assessment before prescribing TMB.

Benzalkonium chloride-treated anorectums mimicked endothelin-3-deficient aganglionic anorectums on manometry.

BACKGROUND/PURPOSE: The anorectal spasticity in Hirschsprung disease may be caused by the absence of enteric ganglia and/or the presence of hypertrophic nerves. Anorectal manometry of chemically denervated rectums was compared with that of congenital aganglionic rectums that also possessed hypertrophic nerves. METHODS: Aganglionic and ganglionic littermates were produced from breeding heterozygous lethal-spotted mice. Benzalkonium chloride was endorectally injected into ganglionic rectums to ablate the neural elements. Anorectal manometry was performed before the injection and on day 14 postinjection. The anorectal resting pressure was calculated based on the manometric tracing. Rectums were retrieved on day 14 for histologic evaluations. RESULTS: Benzalkonium chloride injection successfully ablated the rectal ganglia. Although ganglionic littermates exhibited regular slow waves on anorectal manometry, aganglionic lethal-spotted mice showed irregular waves. Similar to lethal spotted mice, benzalkonium chloride-treated mice exhibited significantly higher anorectal resting pressure than that of ganglionic mice. The slow waves were absent in benzalkonium chloride-treated mice. CONCLUSION: Benzalkonium chloride treatment produced aganglionic rectums that had higher resting pressure similar to the congenital aganglionic rectums. This suggests that hypertrophic nerves in congenital aganglionosis are not necessary to produce the anorectal spasticity.

Differential gene expression and functional analysis implicate novel mechanisms in enteric nervous system precursor migration and neuritogenesis.

Enteric nervous system (ENS) development requires complex interactions between migrating neural-crest-derived cells and the intestinal microenvironment. Although some molecules influencing ENS development are known, many aspects remain poorly understood. To identify additional molecules critical for ENS development, we used DNA microarray, quantitative real-time PCR and in situ hybridization to compare gene expression in E14 and P0 aganglionic or wild type mouse intestine. Eighty-three genes were identified with at least two-fold higher expression in wild type than aganglionic bowel. ENS expression was verified for 39 of 42 selected genes by in situ hybridization. Additionally, nine identified genes had higher levels in aganglionic bowel than in WT animals suggesting that intestinal innervation may influence gene expression in adjacent cells. Strikingly, many synaptic function genes were expressed at E14, a time when the ENS is not needed for survival. To test for developmental roles for these genes, we used pharmacologic inhibitors of Snap25 or vesicle-associated membrane protein (VAMP)/synaptobrevin and found reduced neural-crest-derived cell migration and decreased neurite extension from ENS precursors. These results provide an extensive set of ENS biomarkers, demonstrate a role for SNARE proteins in ENS development and highlight additional candidate genes that could modify Hirschsprung's disease penetrance.

Selective chemical ablation of the enteric plexus in mice.

Although genetically aganglionic mice such as piebald lethal and lethal spotted mice exhibit striking similarities to the human condition of Hirschsprung's disease (HD), the aganglionic segment is very short and always located in the distal part of the rectum. Topical application of benzalkonium chloride (BAC) to the rectum of rats has been reported to result in segmental aganglionosis. To induce chemical ablation of the enteric plexus in mice to produce an aperistaltic narrow segment simulating HD, 32 mice were divided into three groups: (1) abdominal (n=12), for sigmoid colon treatment; (2) rectal (n=10), for rectum treatment; and (3) controls (n=10). For groups 1 and 2, 0.1% BAC was applied to a 1-cm serosal surface of the bowel for 15 min. In the controls, isotonic saline was applied in this fashion. A detailed histologic examination was performed using hematoxylin and eosin staining and acetylcholinesterase histochemistry. Ten animals (9 in group 1 and 1 in group 2) died 1 to 9 weeks after BAC treatment. Autopsy revealed a narrow segment of bowel at the site of BAC treatment and marked dilatation of the bowel proximal to the narrow segment. The remaining animals were killed 12 weeks after BAC treatment. Histologic examination demonstrated normal myenteric and submucous plexuses in the controls, whereas there was a total lack of innervation in the BAC-treated segments.Topical application of BAC thus successfully produced a narrow aganglionic segment of bowel in normal mice. This model provides the basis for future studies to investigate the pathophysiology of HD and megacolon and for comparison with genetically aganglionic mice.

Prune-belly syndrome associated with extra-abdominal abnormalities in a 7-year-old boy.

Prune-belly syndrome (PBS) is an association of abdominal wall deficiency, genitourinary anomalies, and in males, cryptorchidism. Other congenital anomalies are associated with PBS, particularly musculoskeletal deformities and gastrointestinal tract anomalies. In this report, a seven-year-old boy with PBS had mega cisterna magna variant, microcornea, aortic stenosis with bicuspid aortic valves, cholelithiasis, and Hirschsprung's disease. Coexistence of these abnormalities with PBS supports the concept of PBS being caused by an early disturbance of not only mesodermal development but also of the other germ layers. There was maternal ingestion of drugs in the 1st month of gestation. All cases with PBS should be evaluated thoroughly for extra-abdominal abnormalities resulting from disturbances of ectodermal and endodermal development. Even though disturbances related to ectodermal and endodermal development may be asymptomatic, early diagnosis of the disturbances may help in preventing possible future problems.