Gastrointestinal function in chronic renal failure

Gastrointestinal challenges in nephropathic cystinosis: clinical perspectives

Gastrointestinal (GI) sequelae, such as vomiting, hyperacidity, dysphagia, dysmotility, and diarrhea, are nearly universal among patients with nephropathic cystinosis. These complications result from disease processes (e.g., kidney disease, cystine crystal accumulation in the GI tract) and side effects of treatments (e.g., cysteamine, immunosuppressive therapy). GI involvement can negatively impact patient well-being and jeopardize disease outcomes by compromising drug absorption and patient adherence to the strict treatment regimen required to manage cystinosis. Given improved life expectancy due to advances in kidney transplantation and the transformative impact of cystine-depleting therapy, nephrologists are increasingly focused on addressing extra-renal complications and quality of life in patients with cystinosis. However, there is a lack of clinical data and guidance to inform GI-related monitoring, interventions, and referrals by nephrologists. Various publications have examined the prevalence and pathophysiology of selected GI complications in cystinosis, but none have summarized the full picture or provided guidance based on the literature and expert experience. We aim to comprehensively review GI sequelae associated with cystinosis and its treatments and to discuss approaches for monitoring and managing these complications, including the involvement of gastroenterology and other disciplines.

Mallory-Weiss syndrome in four hemodialysis patients: a case study

BACKGROUND

Hemodialysis patients are prone to gastrointestinal bleeding, and Mallory-Weiss syndrome (MWS) is one of the causes. Mallory-Weiss syndrome is often induced by severe vomiting, manifests as upper gastrointestinal bleeding, and is self-limited with a good prognosis. However, mild vomiting in hemodialysis patients can lead to the occurrence of MWS, and the mild early symptoms are easy to misdiagnose, leading to the aggravation of the disease.

CASE PRESENTATION

In this paper, we report four hemodialysis patients with MWS. All patients displayed symptoms of upper gastrointestinal bleeding. The diagnosis of MWS was confirmed by gastroscopy. One patient had a history of severe vomiting; however, the other three reported histories of mild vomiting. Three patients received the conservative hemostasis treatment, and the gastrointestinal bleeding stopped. One patient underwent the gastroscopic and interventional hemostasis treatments. The conditions of three of the patients improved. Unfortunately, one of the patients died due to the cardia insufficiency.

CONCLUSIONS

We think that the mild symptoms of MWS are easily covered up by other symptoms. This may lead to delays in diagnosis and treatment. For patients with severe symptoms, gastroscopic hemostasis is still the first choice, and interventional hemostasis can also be considered. For patients with mild symptoms, drug hemostasis is the first consideration.

Helicobacter pylori-negative Chronic Gastritis in Children: A Systematic Review

OBJECTIVES

To systematically review the current evidence on Helicobacter pylori-negative chronic gastritis including natural history, available therapies and outcomes.

METHODS

Articles providing data on the prevalence, treatment or outcomes of Helicobacter pylori-negative gastritis were identified through a systematic search in the MEDLINE and EMBASE databases. All original research articles from human studies until October 31, 2021, were included.

RESULTS

A total of 54 studies were included consisted of eosinophilic gastritis (n = 9), autoimmune gastritis (n = 11), collagenous gastritis (n = 16), focally enhanced gastritis (n = 6), lymphocytic gastritis (n = 5) and other causes including idiopathic gastritis and chronic renal failure related (n = 7). Most of the included studies were either cross-sectional or longitudinal cohorts except for collagenous gastritis, which mainly included case reports and case series. The prevalence of paediatric eosinophilic gastritis ranges between 5 and 7/100,000 and patients have generally favourable outcome with 50% to 70% clinical and histological response to either corticosteroids or elimination diets. Autoimmune gastritis and collagenous gastritis are extremely rare entities, commonly present with refractory iron deficiency anaemia, while lymphocytic gastritis is relatively common (10%-45%) in children with coeliac disease. Data on treatments and outcomes of autoimmune, collagenous, and focally enhanced gastritis are lacking with limited data implying poor response to therapy in the former 2 diagnoses.

CONCLUSIONS

Helicobacter pylori-negative gastritis is uncommonly reported, mainly in small cohorts, mixed adult-paediatric cohorts or as sporadic case reports. As common symptoms are not specific, thus not always result in an endoscopic evaluation, the true prevalence of these distinct disorders may be underestimated, and thus under reported.

A Physiological Approach to Pharmacokinetics in Chronic Kidney Disease

The conventional approach to approximating the pharmacokinetics of drugs in patients with chronic kidney disease (CKD) only accounts for changes in the estimated glomerular filtration rate. However, CKD is a systemic and multifaceted disease that alters many body systems. Therefore, the objective of this exercise was to develop and evaluate a whole-body mechanistic approach to predicting pharmacokinetics in patients with CKD. Physiologically based pharmacokinetic models were developed in PK-Sim v8.0 (www.open-systems-pharmacology.org) to mechanistically represent the disposition of 7 compounds in healthy human adults. The 7 compounds selected were eliminated by glomerular filtration and active tubular secretion by the organic cation transport system to varying degrees. After a literature search, the healthy adult models were adapted to patients with CKD by numerically accounting for changes in glomerular filtration rate, kidney volume, renal perfusion, hematocrit, plasma protein concentrations, and gastrointestinal transit. Literature-informed interindividual variability was applied to the physiological parameters to facilitate a population approach. Model performance in CKD was evaluated against pharmacokinetic data from 8 clinical trials in the literature. Overall, integration of the CKD parameterization enabled exposure predictions that were within 1.5-fold error across all compounds and patients with varying stages of renal impairment. Notable improvement was observed over the conventional approach to scaling exposure, which failed in all but 1 scenario in patients with advanced CKD. Further research is required to qualify its use for first-in-CKD dose selection and clinical trial planning for a wider selection of renally eliminated compounds, including those subject to anion transport.

Adipokines and Gut Hormones in End-Stage Renal Disease

Cachexia is common in end-stage renal disease (ESRD) patients, and it is an important risk factor for poor quality of life and increased mortality and morbidity. Chronic inflammation is an important cause of cachexia in ESRD patients. In the present review, we examine recent evidence suggesting that adipokines or adipocytokines such as leptin, adiponectin, resistin, tumor necrosis factor α, interleukin-6, and interleukin-1β may play important roles in uremic cachexia. We also review the physiology and the potential roles of gut hormones, including ghrelin, peptide YY, and cholecystokinin in ESRD. Understanding the molecular pathophysiology of these novel hormones in ESRD may lead to novel therapeutic strategies.

Pharmacokinetics in children with chronic kidney disease

In children, the main causes of chronic kidney disease (CKD) are congenital diseases and glomerular disorders. CKD is associated with multiple physiological changes and may therefore influence various pharmacokinetic (PK) parameters. A well-known consequence of CKD on pharmacokinetics is a reduction in renal clearance due to a decrease in the glomerular filtration rate. The impact of renal impairment on pharmacokinetics is, however, not limited to a decreased elimination of drugs excreted by the kidney. In fact, renal dysfunction may lead to modifications in absorption, distribution, transport, and metabolism as well. Currently, insufficient evidence is available to guide dosing decisions on many commonly used drugs. Moreover, the impact of maturation on drug disposition and action should be taken into account when selecting and dosing drugs in the pediatric population. Clinicians should take PK changes into consideration when selecting and dosing drugs in pediatric CKD patients in order to avoid toxicity and increase efficiency of drugs in this population. The aim of this review is to summarize known PK changes in relation to CKD and to extrapolate available knowledge to the pediatric CKD population to provide guidance for clinical practice.

Distal Colon Motor Dysfunction in Mice with Chronic Kidney Disease: Putative Role of Uremic Toxins

Although gastrointestinal complications are a common feature of patients with chronic kidney disease (CKD), the impact of uremia on bowel motility remains poorly understood. The present study was, therefore, designed to investigate the impact of uremia on gut motility. Kidney failure was induced in mice by chemical nephrectomy using an adenine diet (0.25% w/w). Gastrointestinal transit time and colon motility were explored in vivo and ex vivo. Colons from control mice were incubated with uremic plasma or uremic toxins (urea, indoxyl-sulfate or p-cresyl-sulfate) at concentrations encountered in patients with end-stage renal disease. Mice fed an adenine diet for 3 weeks exhibited a 3-fold increase in plasma urea (p < 0.001) evidencing kidney failure. The median gastrointestinal transit time was doubled (1.8-fold, p < 0.001) while a reduction in colonic propulsive motility was observed in CKD mice (3-fold, p < 0.001). Colon from CKD mice exhibited an abnormal pattern of contraction associated with a blunted maximal force of contraction. Control colons incubated with plasma from hemodialysis patients exhibited a blunted level of maximal contraction (p < 0.01). Incubation with urea did not elicit any difference but incubation with indoxyl-sulfate or p-cresyl-sulfate decreased the maximal force of contraction (−66% and −55%, respectively. p < 0.01). Taken together, these data suggest that uremia impairs colon motility probably through the retention of uremic toxins. Colon dysmotility might contribute to the gastrointestinal symptoms often reported in patients with CKD.

Extracellular acidosis selectively inhibits pharmacomechanical coupling induced by carbachol in strips of rat gastric fundus

NEW FINDINGS

What is the central question of this study? Acute acidosis that results from short-term exercise is involved in delayed gastric emptying in rats and the lower responsiveness of gastric fundus strips to carbachol. Does extracellular acidosis decrease responsiveness to carbachol in tissues of sedentary rats? How? What is the main finding and its importance? Extracellular acidosis inhibits cholinergic signalling in the rat gastric fundus by selectively influencing the G_q/11 protein signalling pathway. Acute acidosis that results from short-term exercise delays gastric emptying in rats and decreases the responsiveness to carbachol in gastric fundus strips. The regulation of cytosolic Ca²⁺ concentrations appears to be a mechanism of action of acidosis. The present study investigated the way in which acidosis interferes with gastric smooth muscle contractions. Rat gastric fundus isolated strips at pH 6.0 presented a lower magnitude of carbachol-induced contractions compared with preparations at pH 7.4. This lower magnitude was absent in carbachol-stimulated duodenum and KCl-stimulated gastric fundus strips. In Ca²⁺ -free conditions, repeated contractions that were induced by carbachol progressively decreased, with no influence of extracellular pH. In fundus strips, CaCl₂ -induced contractions were lower at pH 6.0 than at pH 7.4 but only when stimulated in the combined presence of carbachol and verapamil. In contrast, verapamil-sensitive contractions that were induced by CaCl₂ in the presence of KCl did not change with pH acidification. In Ca²⁺ store-depleted preparations that were treated with thapsigargin, the contractions that were induced by extracellular Ca²⁺ restoration were smaller at pH 6.0 than at pH 7.4, but relaxation that was induced by SKF-96365 (an inhibitor of store-operated Ca²⁺ entry) was unaltered by extracellular acidification. At pH 6.0, the phospholipase C inhibitor U-73122 relaxed carbachol-induced contractions less than at pH 7.4, and this phenomenon was absent in tissue that was treated with the RhoA kinase blocker Y-27632. Thus, extracellular acidosis inhibited pharmacomechanical coupling in gastric fundus by selectively inhibiting the G_q/11 protein signalling pathway, whereas electromechanical coupling remained functionally preserved.

Endoscopic alterations in a cohort of hemodialysis patients: a cross-sectional study

Introduction

Although the association between chronic kidney disease and dyspepsia is widely known, it remains poorly investigated. Among the types of gastric inflammation that lead to symptoms, erosive antral gastritis is the most common form. A direct correlation between the urea serum levels and the time in hemodialysis with the onset of gastric metaplasia and dyspepsia can be observed. The aim of this study was to report the endoscopic alterations found in hemodialysis patients.

Methods

This is a cross-sectional study based on the medical records of 95 patients older than 18 years who were diagnosed with chronic kidney disease. The results of endoscopies performed up to 6 months before the beginning of the study were included.

Results

Among the 95 studied patients, 56.84% were male, 60% were Caucasian, and 71.57% used proton pump inhibitors. The endoscopic alteration most frequently observed was erosive gastritis (77% of the cases); however, the frequency of the alteration that caused the symptoms was irrelevant. The antrum was the most common site of involvement (55.79%).

Conclusion

Patients with chronic kidney disease often show dyspeptic symptoms. Other abnormalities are common but are not correlated with such symptoms. In conclusion, this study identified the endoscopic alterations that are most often observed in hemodialysis patients; erosive and enanthematous gastritis were the most common forms observed.

Phlorizin pretreatment reduces acute renal toxicity in a mouse model for diabetic nephropathy

Streptozotocin (STZ) is widely used as diabetogenic agent in animal models for diabetic nephropathy (DN). However, it is also directly cytotoxic to kidneys, making it difficult to distinguish between DN-related and STZ-induced nephropathy. Therefore, an improved protocol to generate mice for DN studies, with a quick and robust achievement of the diabetic state, without direct kidney toxicity is required. To investigate the mechanism leading to STZ-induced nephropathy, kidney damage was induced with a high dose of STZ. This resulted in delayed gastric emptying, at least partially caused by impaired desacyl ghrelin clearance. STZ uptake in the kidneys is to a large extent mediated by the sodium/glucose cotransporters (Sglts) because the Sglt inhibitor phlorizin could reduce STZ uptake in the kidneys. Consequently, the direct toxic effects in the kidney and the gastric dilatation were resolved without interfering with the β-cell toxicity. Furthermore, pancreatic STZ uptake was increased, hereby decreasing the threshold for β-cell toxicity, allowing for single low non-nephrotoxic STZ doses (70 mg/kg). In conclusion, this study provides novel insights into the mechanism of STZ toxicity in kidneys and suggests a more efficient regime to induce DN with little or no toxic side effects.

Electrogastrography in adults and children: the strength, pitfalls, and clinical significance of the cutaneous recording of the gastric electrical activity

Cutaneous electrogastrography (EGG) is a non-invasive technique to record gastric myoelectrical activity from the abdominal surface. Although the recent rapid increase in the development of electrocardiography, EGG still suffers from several limitations. Currently, computer analysis of EGG provides few reliable parameters, such as frequency and the percentage of normal and altered slow wave activity (bradygastria and tachygastria). New EGG hardware and software, along with an appropriate arrangement of abdominal electrodes, could detect the coupling of the gastric slow wave from the EGG. At present, EGG does not diagnose a specific disease, but it puts in evidence stomach motor dysfunctions in different pathological conditions as gastroparesis and functional dyspepsia. Despite the current pitfalls of EGG, a multitasking diagnostic protocol could involve the EGG and the (13)C-breath testing for the evaluation of the gastric emptying time-along with validated gastrointestinal questionnaires and biochemical evaluations of the main gastrointestinal peptides-to identify dyspeptic subgroups. The present review tries to report the state of the art about the pathophysiological background of the gastric electrical activity, the recording and processing methodology of the EGG with particular attention to multichannel recording, and the possible clinical application of the EGG in adult and children.

Helicobacter pylori infection and gastroduodenal lesions in children with chronic kidney disease stage V

BACKGROUND

This study aimed to investigate the dyspeptic symptoms, endoscopic findings, and frequency of Helicobacter pylori (Hp) infection in children with chronic kidney disease (CKD) stage V, and to compare findings in peritoneal dialysis (PD) and hemodialysis (HD) patients.

METHODS

Sixty-five patients on PD (n = 36) or HD (n = 29) were included. Age, gender, duration and type of dialysis, and dyspeptic complaints were recorded. All patients underwent endoscopy. Rapid urease tests were performed in all patients and antral biopsy examinations done in suitable patients to investigate presence of Hp infection.

RESULTS

The mean age of patients (55 % male) was 13.9 ± 3.6 years. Frequency of dyspepsia was 43 % and was similar in HD and PD groups. The most frequent dyspeptic symptoms were early satiety (21.5 %) and bloating (17 %). Abnormal endoscopic findings were present in 81.5 % of patients (similar in both groups), and the most common lesion was gastritis (35.5 %). Hp positivity was determined in 37 % of the patients, which was similar in both groups. No significant relationship was found between dyspeptic symptoms and Hp infection. Hp infection was found to be significantly higher in 41.5 % of the patients with gastroduodenal lesions. Abnormal endoscopic findings were significantly higher in severely dyspeptic patients (88.9 %).

CONCLUSIONS

We think performing an upper gastrointestinal tract examination and Hp screening may be helpful in renal transplant candidates with severe dyspeptic symptoms.

Gastric emptying study by scintigraphy in patients with chronic renal failure

BACKGROUND AND OBJECTIVES

This study had the purpose of studying gastric emptying in patients with chronic renal failure.

MATERIAL AND METHOD

Thirty patients with chronic renal failure were studied, 16 in conservative clinical treatment and 14 in hemodialysis for over six months. The control group (CTL) was composed of 18 asymptomatic volunteers. The method of gastric emptying study was scintigraphy. The standardized test meal was an omelet of three chicken eggs prepared with colloidal sulfur marked with 185 MBq of 99m technetium. Gastric retention curves were studied and T½ of gastric emptying was obtained from them. A T½ value corresponding to the average of T½ values of control group plus twice standard deviation was considered nornmal. Statistical tests used were χ(2) and Kruskal-Wallis.

RESULTS

There was no statistically significant difference with regard to total gastric retention curves and T½ of gastric emptying, which was similar in three studied groups. Nine patients had high T½ of gastric emptying, above 125 minutes. These patients were equally distributed among both genders and conservative clinical treatment and hemodialysis groups.

CONCLUSIONS

We concluded that gastric retention rate and T½ of gastric emptying in patients with chronic renal failure in conservative clinical treatment and hemodialysis does not differ from the healthy patients group. Hemodialysis does not seem to reduce the risk of gastric retention in patients with chronic renal failure.

Serum gastrin levels and gastroduodenal lesions in children with chronic renal failure on continuous ambulatory peritoneal dialysis: a single-center experience

OBJECTIVE

The aim of this study was to determine serum gastrin levels and gastroduodenal lesions in children with chronic renal failure (CRF) on continuous ambulatory peritoneal dialysis (CAPD).

METHODS

A total of 19 patients (mean age: 11.7±3.9 years, M/F: 1.37) with CRF on CAPD and 20 age-matched and sex-matched patients (mean age: 10.2±1.4 years, M/F: 1.5) with peptic ulcers were included in the study. Serum gastrin, creatinine, phosphate, and parathormone levels were determined. Upper gastrointestinal endoscopy was performed in all patients.

RESULTS

The basal gastrin concentrations of CAPD patients were significantly higher than those of patients with peptic ulcer disease without CRF (124.2±59.1 and 53.0±9.4 pg/ml, respectively) (P<0.001). A significant correlation was found between age, duration of uremia, and serum gastrin levels (r=0.59, P<0.01; r=0.60, P<0.01, respectively). No correlation was found between the duration of CAPD and serum gastrin levels in the patient group. Of the patients, 73.6% had abnormal upper gastrointestinal endoscopic findings. The gastroduodenal lesion observed was hemorrhagic gastritis (31.5%), followed by hemorrhagic gastroduodenitis (26.3%), gastric nodular gastritis (10.5%), and polyps (10.5%).

CONCLUSION

On the basis of our findings, such as higher serum gastrin levels in patients with CRF than those of the control group and the frequent endoscopic findings of gastroduodenal lesions in most of the patients, we recommend that an endoscopic examination should be considered for all the children with CRF on CAPD awaiting renal transplantation even if they are asymptomatic.

Helicobacter pylori status and esophagogastroduodenal mucosal lesions in patients with end-stage renal failure on maintenance hemodialysis

OBJECTIVES

The aim of this study was to elucidate the impact of Helicobacter pylori infection on esophagogastroduodenal mucosal lesions in patients with end-stage renal failure on maintenance hemodialysis (HD).

METHODS

An upper endoscopy and the (13)C-urea breath test were performed in 198 patients on maintenance HD. Clinical features, serum pepsinogen levels and esophagogastroduodenal mucosal lesions were compared between H. pylori-positive and H. pylori-negative patients. Risk factors associated with esophagogastroduodenal mucosal lesion were determined by multivariate analyses.

RESULTS

The upper endoscopy revealed that gastric erosion was the most frequent (58%) type of esophagogastroduodenal mucosal lesion, followed by duodenal erosion (18%), gastric ulcer (14%), gastroesophageal reflux disease (10%), and duodenal ulcer (7%). Of the 198 patients enrolled in the study, 81 were positive and 117 patients were negative for H. pylori infection. The time duration after the introduction of HD was significantly longer and serum pepsinogen I/II ratio was significantly higher in H. pylori-negative patients than in H. pylori-positive patients. Multivariate analyses revealed that the H. pylori infection was an independent, protective factor for gastric erosion (odds ratio 0.38; 95% confidence interval 0.21-0.70), while the infection was unrelated to other mucosal lesions.

CONCLUSIONS

The most common mucosal lesion observed in our study cohort, all of whom were patients on maintenance HD, was gastric erosion. The high prevalence of this type of lesion may be explained partly by the cure of H. pylori infection during the clinical course of maintenance HD.

The prevalence of gallbladder stones is higher among patients with chronic kidney disease in Taiwan

The pathogenesis of gallstone disease is multifactorial. Few studies have focused on gallbladder stones in the chronic kidney disease population in Taiwan. We conducted the current study to determine the prevalence of gallbladder stones in populations with and without chronic kidney disease.This was a hospital-based, cross-sectional study. We retrospectively analyzed the patients receiving periodic health examinations at 1 medical center in Taiwan from 2001 to 2004. In all, 4773 patients were enrolled in the study. Chronic kidney disease was defined as a glomerular filtration rate less than 60 mL/min per 1.73 m by the Modification of Diet in Renal Disease formula. Odds ratio (OR) and 95% confidence intervals (CI) were expressed using a multivariate logistic regression analysis.We studied 2686 men (56.3%) and 2087 women (43.7%). The mean age was 49.1 +/- 12.2 years (range, 20-87 yr). The prevalence of gallbladder stones was 13.1% in the group of patients with chronic kidney disease and 4.9% in the group of patients without chronic kidney disease (p < 0.001). After controlling for the other covariates, multivariate logistic regression analysis showed that increasing age (aged 40-64 yr vs. 20-39 yr, OR = 3.06, 95% CI = 1.81-5.15; and > or =65 yr vs. 20-39 yr, OR = 6.13, 95% CI = 3.42-10.98), chronic kidney disease (OR = 1.58, 95% CI = 1.01-2.47), body mass index > or =27 kg/m (OR = 1.39, 95% CI = 1.02-1.91), metabolic syndrome (OR = 1.45, 95% CI = 1.08-1.94), and cirrhosis (OR = 4.23, 95% CI = 1.25-14.29) were significantly related to gallbladder stone disease.The prevalence of gallbladder stones in patients with chronic kidney disease is significantly higher than in those without chronic kidney disease. Our findings suggest that increasing age, chronic kidney disease, body mass index > or =27 kg/m, metabolic syndrome, and cirrhosis are the related factors for gallbladder stone formation.

The effect of renal replacement therapies on serum gastrointestinal system hormones

BACKGROUND

The kidney is a major site for the inactivation, degradation, and clearance of a variety of peptide hormones. It has been shown that the uremia increases or decreases gastrointestinal system (GIS) hormones. Moreover, studies investigating the serum GIS hormones levels in chronic renal failure (CRF) were conducted mainly in a particular period of the renal replacement therapy, and the changes caused by continuous ambulatory peritoneal dialysis (CAPD) and hemodialysis (HD) could not be fully demonstrated. In this study, we investigated the effect of CAPD and HD on serum GIS hormones (amylase, lipase, trypsinogen, and gastrin) levels in CRF patients who were diagnosed for the first time.

METHODS

Serum amylase, lipase, trypsinogen, and gastrin levels were measured in 36 patients who were just diagnosed with CRF, 22 patients with CAPD and 14 patients with HD. GIS hormones of these patients were measured before treatment and three months from the beginning of CAPD and HD treatment. As the control group, 20 normal healthy cases with well-matched age and gender were used.

RESULTS

The mean serum amylase, lipase, secretin, and gastrin levels were found meaningfully decreased according to the beginning values at third months of the CAPD and HD treatment. However, they were higher than control group.

CONCLUSION

In patients receiving CAPD or HD as renal replacement therapy, GIS hormone levels were found to be lower, albeit higher than the healthy control group.

Lipoprotein metabolism in chronic renal insufficiency

Chronic renal insufficiency (CRI) is associated with a characteristic dyslipidemia. Findings in children with CRI largely parallel those in adults. Moderate hypertriglyceridemia, increased triglyceride-rich lipoproteins (TRL) and reduced high-density lipoproteins (HDL) are the most usual findings, whereas total and low-density lipoprotein cholesterol (LDL-C) remain normal or modestly increased. Qualitative abnormalities in lipoproteins are common, including small dense LDL, oxidized LDL, and cholesterol-enriched TRL. Measures of lipoprotein lipase and hepatic lipase activity are reduced, and concentrations of apolipoprotein C-III are markedly elevated. Still an active area of research, major pathophysiological mechanisms leading to the dyslipidemia of CRI include insulin resistance and nonnephrotic proteinuria. Sources of variability in the severity of this dyslipidemia include the degree of renal impairment and the modality of dialysis. The benefits of maintaining normal body weight and physical activity extend to those with CRI. In addition to multiple hypolipidemic pharmaceuticals, fish oils are also effective as a triglyceride-lowering agent, and the phosphorous binding agent sevelamer also lowers LDL-C. Emerging classes of hypolipidemic agents and drugs affecting sensitivity to insulin may impact future treatment. Unfortunately, cardiovascular benefit has not been convincingly demonstrated by any trial designed to study adults or children with renal disease. Therefore, it is not possible at this time to endorse general recommendations for the use of any agent to treat dyslipidemia in children with chronic kidney disease.

Effect of chronic renal failure on foregut smooth muscle reactivity: an experimental study

PURPOSE

An association between chronic renal failure (CRF) and gastroesophageal reflux (GER) is well known. The aim of this study was to pharmacologically characterize and investigate the possible contribution of smooth muscle reactivity pathways involving GER on the CRF rat model.

MATERIAL AND METHODS

Chronic renal failure was created in Sprague-Dawley rats by 5 of 6 nephrectomy. The rats were divided into 2 groups: the CRF-induced group (CRF group) and the sham-operated group (control group). Esophageal smooth muscle strips were studied in vitro for their contractile (KCl, carbachol) and relaxant (isoproterenol, serotonin, and papaverine) response to receptor activation in the organ chambers set up. Subsequently, the in vitro lower esophageal sphincter (LES) smooth muscle study was generated by KCl, carbachol, isoproterenol, nicotine, sodium nitroprusside (SNP), and papaverine.

RESULTS

Compared with controls, esophageal strips taken from CRF-induced rats associated with decreased smooth muscle responses to carbachol, serotonin, and increased response to KCl. Isoproterenol- and papaverine-induced relaxant responses were not affected. Contractility of the isolated LES strips were significantly increased to KCl and carbachol in the CRF group compared with the control group. Similar relaxant responses were obtained in LES strips stimulated by isoproterenol, SNP, and papaverine in the CRF and control group. Nicotine-induced relaxant responses were decreased in the CRF group compared with the control group.

CONCLUSIONS

Our study revealed alterations of receptor-dependent esophageal and LES smooth muscle reactivity in the CRF-induced rats. Impaired foregut smooth muscle reactivity may contribute to the development of GER-related functional abnormalities in patients with CRF.

Gastroduodenal lesions and Helicobacter pylori infection in dyspeptic patients with and without chronic renal failure

BACKGROUND

Patients with chronic renal failure (CRF) often have dyspeptic symptoms and may develop peptic disease or digestive disorders leading to severe gastrointestinal complications. The primary aim of this study was to evaluate the prevalence of peptic lesions and Helicobacter pylori infection, and the severity of dyspeptic symptoms, in dyspeptic patients with and without CRF. Our secondary aim was to investigate whether uremic status may affect the diagnostic efficiency of the [13]C-urea breath test ([13]C-UBT).

PATIENTS AND METHODS

We consecutively enrolled in the study 50 dyspeptic patients with chronic kidney failure (mean age 52 +/- 5 years), of whom 11 were on hemodialysis treatment (HD), and 93 subjects (mean age 54 +/- 7 years) with chronic dyspepsia and normal renal function (NRF). All patients completed an oriented and validated questionnaire scoring the severity of nine dyspeptic symptoms (i.e. epigastric pain, epigastric burning, postprandial fullness, early satiety, bloating, belching, nausea and vomiting) and underwent upper endoscopy with multiple bioptic sampling for rapid urease test and histological examination, [13]C-UBT and HpSA test.

RESULTS

The prevalences of peptic lesions and H. pylori infection and mean symptom score were 74%, 52% and 3.5 +/- 3, respectively, in dyspeptic patients with CRF and 18%, 36% and 8 +/- 5, respectively, in dyspeptic patients with NRF. The diagnostic accuracy of [13]C-UBT with respect to histological diagnosis was 94% and 97% for dyspeptic patients with and without renal failure, respectively.

CONCLUSIONS

1, A high frequency of peptic lesions and low symptom scores were observed in uremic patients in spite of H. pylori infection; 2, uremic status did not affect the diagnostic accuracy of [13]C-UBT.

Gastric electric activity assessed by electrogastrography and gastric emptying scintigraphy in adolescents with eating disorders

BACKGROUND

Patients with eating disorders can refer to a variety of gastrointestinal symptoms, sometimes to justify reduced food intake and vomiting. The authors investigated whether adolescent patients with eating disorders and dyspeptic symptoms have altered gastric electric activity and abnormal gastric emptying as assessed respectively by electrogastrography and scintigraphy.

METHODS

Twenty-eight patients (18 with anorexia and 10 with bulimia) and 16 healthy volunteers underwent electrogastrography; 20 of the 28 patients (14 with anorexia and 6 with bulimia) underwent gastric emptying scintigraphy. Electrogastrography with bipolar recording lasted 1 hour, 30 minutes before and after a standard meal. Before gastric emptying scintigraphy, patients fasted overnight; during testing, they ingested a solid meal labeled with technetium-99m sulfur colloid. The ratio of fasting to postprandial electrogastrographic variables was evaluated using the Wilcoxon matched-pair test. The Mann- Whitney test was used to compare absolute values for electrogastrographic data in each group. The Student paired t test was used to compare scintigraphic results expressed as percentage of gastric emptying at 60 minutes and as the gastric emptying time (T(1/2)).

RESULTS

Patients with bulimia significantly differed from those with anorexia and control subjects regarding the amount of normal gastric electric activity and bradygastria, and from patients with anorexia only regarding tachygastria. These electrogastrographic variables did not differ significantly between patients with anorexia and control subjects. Gastric emptying time (T(1/2)) was significantly longer in patients with bulimia than in those with anorexia.

CONCLUSIONS

Adolescent patients with bulimia who complain of dyspeptic symptoms have documentable abnormalities of gastric electric activity and emptying, whereas their counterparts with anorexia, probably owing to their shorter disease duration, do not.

Small bowel motility and colonic transit are altered in dogs with moderate renal failure

Although gastrointestinal complications are common in patients with renal disease, the effects of renal dysfunction on bowel motility and gut transit times are not well known. We assessed gastrointestinal electromyographic activity, gastric emptying rate, orocolonic transit time, oroanal transit time, and xylose absorption before and after surgically inducing a 66% decrease in glomerular filtration rate in dogs. Moderate renal failure induced no gross or microscopic gastrointestinal lesions but caused a 16-42% increase in gastrointestinal motility indexes. We found a 24% decrease in the propagation velocity of the myoelectrical migrating complex in the duodenojejunal segment, a 30% decrease in phase I duration in duodenal and jejunal regions, a 20% increase in the total irregular electrical activity of the small intestine, and a 22% increase in duration of the meal response in the duodenum and jejunum. Renal failure did not change xylose absorption, gastric emptying rate, and orocolonic transit time but decreased colonic transit time by 38%. The mean weight of feces was increased. These results indicate that moderate renal failure alters duodenojejunal motility and decreases colonic transit time.

Peptic ulcer disease in children

A peptic ulcer in a child looks the same as it does in an adult, and many of the aetiologies of peptic ulcer disease in children are similar to those in adults. However, there are many differences between children and adults, especially in the areas of clinical presentation, the prevalences of different types of ulcer disease, and the prevalence of complications of ulcer disease. Therefore the approach to diagnosis and management in children is often at variance with that in adults. One important example is the approach to suspected Helicobacter pylori (H. pylori) disease in children, in which consensus groups have advised a considerably different approach in children. While the chapter deals with the full range of peptic ulcer disease in children, the focus is on those aspects in which there are differences between adults and children.

Evaluation and treatment of chronic renal failure

Chronic renal failure (CRF) is the irreversible deterioration of renal function that gradually progresses to end stage renal disease (ESRD). The chief causes of CRF include obstructive uropathy, primary glomerular diseases, reflux nephropathy and hypoplastic or dysplastic kidneys. Progressive hyperperfusion and hyperfiltration causes increasing glomerular injury and further renal damage. Symptoms of CRF are usually seen when GFR is between 10-25% of normal. Children with severe CRF often suffer from failure to thrive, growth retardation, acidosis, anemia and renal osteodystrophy. Management of CRF aims at retarding progression of renal damage and treatment of complications related to renal dysfunction. Measures suggested to retard progression include protein restriction, strict control of hypertension, use of angiotensin converting enzyme inhibitors and control of hyperlipidemia. Appropriate amounts of protein and calories are recommended to prevent growth failure. Nutritional supplements are often required. The availability of recombinant erythropoietin, calcitriol and human growth hormone has significantly improved the management of these patients. Once ESRD supervenes, renal replacement therapy in the form of chronic peritoneal or hemodialysis and transplantation is necessary.

Gastric dysrhythmia in uremic patients on maintenance hemodialysis

BACKGROUND

Dyspeptic symptoms are common in uremic patients receiving hemodialysis. Investigators have placed emphasis on the changes in histopathology and physiology of the gastrointestinal tract. But not much data about the gastric myoelectric activity are available. The aim of this study was to assess gastric myoelectric activity in uremic patients undergoing hemodialysis.

METHODS

Fifty-eight subjects were enrolled. They were assigned to: group I, uremic patients undergoing hemodialysis with dyspeptic complaints (n = 20); group II, non-uremic patients with matched dyspeptic complaints (n = 20); and group III, healthy volunteers without dyspeptic complaints (n = 18). Gastric myoelectric activity was measured with abdominal surface electrodes in each person. Patients in group I were measured twice, before (group Ia) and after (group Ib) hemodialysis. The data were compared between the groups.

RESULTS

In the prehemodialysis period there was a significantly lower percentage of normal slow-wave frequency when compared with group III (fasting, 66.54%+/-5.39% versus 84.58%+/-3.63%; P < 0.005; fed, 72.25%+/-4.16% versus 89.06%+/-2.57%; P < 0.01). In the post-hemodialysis period the difference was even more profound (fasting, 46.52%+/-4.26% versus 84.58%+/-3.63%; P < 0.001; fed, 51.49%+/-6.89% versus 89.06%+/-2.57%; P < 0.005). Yet, when compared with group II, a significant difference existed only in the post-hemodialysis period (fasting, 46.52%+/-4.26% versus 67.30%+/-3.46%; P<0.001; fed, 51.49%+/-6.89% versus 70.41%+/-4.39%; P < 0.01). Another finding is that hemodialysis decreased the gastric myoelectric activity after hemodialysis (fasting, 66.54%+/-5.39% versus 46.52%+/-4.26%; P < 0.001; fed, 72.25%+/-4.16% versus 51.49%+/-6.89%; P < 0.005).

CONCLUSIONS

Uremic patients undergoing hemodialysis have impaired gastric myoelectric activity. Interestingly, hemodialysis seems to cause deterioration in gastric myoelectric activity.

Gastrin/cholecystokinin type B receptors in the kidney: molecular, pharmacological, functional characterization, and localization

BACKGROUND

Gastrin/cholecystokinin type B receptors (CCKBRs) can be found on parietal cells and smooth muscle cells and are the predominant brain CCK receptors. Recent cloning studies indicate that this is receptor type might also be expressed in the kidney.

MATERIALS AND METHODS

We used Northern blot analysis in guinea pig. kidney and reverse transcriptase polymerase chain reaction (RT-PCR) in several murine kidney cells lines to evaluate this organ for the expression of the CCKBRs. The receptor was pharmacologically characterized by displacement experiments using [125I]-BH-CCKs and various agonists and antagonists. Polyclonal antibodies vs. the CCKBRs were raised in chicken, and immunohistochemistry on tissue sections was used to localize the receptor within the organ. The effect of gastrin on renal cell growth was measured using proximal tubulus (MCT) cells, which were cultured with gastrin (10-9 M) for 24-72 h. Cell counts and [3H]-thymidine incorporation experiments were performed.

RESULTS

CCKBR transcripts can be detected in kidney RNA (tubules > glomeruli > interstitium). RT-PCR revealed CCKBR transcripts in proximal tubules (MCT cells) and in mesangium (MMC). The medullary thick ascending limb of Henle's loop and several control tissues such as liver and muscle were negative. Displacement experiments using [125I]-BH-CCK and various agonists and antagonists identified binding sites with typical CCKBR pharmacology. CCKBRs were localized in the proximal tubulus, distal collecting ducts and mesangium cells. Treatment of rested MCT cells with gastrin 17-1 induced cell proliferation and [3H]-thymidine incorporation by at least 40% compared with normal growth (P < 0.05).

CONCLUSION

These results show for the first time that CCKBRs are present in selected areas of the kidney, and strongly confirm our previous observation that this organ expresses binding sites for [125I]-gastrin. Furthermore, gastrin might act as a growth factor in the kidney.