Serum Citrulline Concentration Research Articles

358 Gastrointestinal Permeability in Unweaned Male Holstein Calves: Colostrum Consumption and Feed Restriction Matters

Abstract Male Holstein calves (n = 80; 42.7 ± 1.44 kg and 14.2 ± 0.81 days of age) were used to evaluate the effects of colostrum consumption and feed restriction on gut functionality in calves subjected to an assembly center simulation (ACS). Well-colostrated (WC) calves received 4L of colostrum within the first 2h after birth and 2L of colostrum in the next 3 feedings, and poor-colostrated (PC) calves received 2L of colostrum within the first 2h after birth. At approximately 14 d of age, calves were subjected to ACS (d-4 to d-1) before a 19h-transport (d0) where they were fed 4L of milk replacer/d (moderate restriction; MO) or 4L of a rehydration solution/d (severe restriction; SV). Treatments were: WCMO, WCSV, PCMO, PCSV and a group of control calves (WCCT) also fed concentrate ad-libitum during ACS and not transported. Twenty-four hours after transportation, a gut permeability test using Cr-EDTA was performed and blood samples for the determination of serum citrulline concentration were collected. Afterwards, one-half of the calves/treatment were euthanized to obtain tissue samples for a gut permeability in vitro analysis and morphometry. Data were analyzed using the MIXED procedure of SAS. Serum Cr-EDTA concentration was greater (P< 0.01) for the WCSV and PCSV compared with the WCMO, PCMO, and WCCT had the least Cr-EDTA concentration after transportation. The PCSV, WCMO and WCSV calves had the least (P< 0.01) serum concentration of citrulline. In vitro measurements of ileum permeability tended (P=0.06) to be greater for PCSV compared with the other treatments. In WCSV, WCMO and PCSV Goblet cells numbers in the ileum were lesser (P=0.02) than in WCCT and PCMO. Feeding rehydrated solution to poor colostrated calves before transport negatively affected gut functionality as indicated by the greatest permeability to Cr-EDTA, the lest serum citrulline concentration, and ileum Globet cells numbers, these findings are supported by the in vitro gut permeability data.

PSIX-18 Use of Feed Additives to Improve the Recovery of Unweaned Calves After Transportation

Abstract Transportation of unweaned calves involves periods of feed restriction and stress without a fully developed immune system and gastrointestinal tract. The use of additives to enhance intake and immunity at arrival could be a strategy to minimize those negative effects. Holstein male calves (n + 39; 16 ± 1.2 d of age and 46 ± 0.1 kg of BW) were used to evaluate the effect of a mixture of feed additives (FA) comprising palatability enhancers, standardized olive pomace extract and tributyrin on performance, energy balance (BHBA), GI functionality (Cr-EDTA and citrulline) and inflammation in calves fed restrictively [2.5 L of milk replacer (MR) twice daily at 12.5%] simulating an assembly center and transported (fasted). Calves were distributed in 3 treatments: non-transported calves fed MR and concentrate without FA since the beginning of the study until weaning (CTR; n=13); and two treatments where calves were fed MR without FA during the restriction period (3d) and transported for 19 h, at arrival calves were offered MR and concentrate without FA (TNA; n =13) or with FA (TWA; n = 13). The MR was offered at 2.5 L twice daily and concentrate ad libitum. Data were analyzed with a mixed-effects model. After transportation (d0), calves on TNA and TWA treatments had a peak of concentrate intake greater (P < 0.05) compared with CTR even those calves had no concentrate before; and on d1, calves on TNA decreased concentrate intake in a greater extent than TWA. Serum IL-1ß on d1 was lesser (P < 0.05) in TNA compared with CTR and TWA. Serum citrulline on d 2 was lesser (P < 0.05) in the TNA compared with TWA. The mixture of FA mitigates the decline of concentrate intake the day after transport and seems to recover enterocytes mass estimated by serum citrulline concentration.

Simulation of feed restriction and fasting: Effects on animal recovery and gastrointestinal permeability in unweaned Angus-Holstein calves

Feed restriction and fasting experienced during commercial production negatively affect unweaned calves' behavior and health status. Transportation and stays at assembly centers are the main factors generating these disorders. For this study, 20 unweaned Angus-Holstein bull calves [44.1 ± 2.04 kg of body weight (BW) and 14.7 ± 0.63 d of age (± standard error)] were used to evaluate the effects of feed restriction and fasting on performance, energy status [serum concentration of glucose, β-hydroxybutyrate (BHB), and nonesterified fatty acids], and gastrointestinal permeability [serum concentration of citrulline, chromium (Cr)-EDTA, lactulose, and d-mannitol]. Calves were randomly assigned to 1 of 4 treatments that simulated the feed restrictions of an assembly center situation on one hand, and the fasting hours during transportation on the other. Treatments were as follows. Control (CT): from d -4 to -1, calves were fed 2.5 L of milk replacer (MR) twice daily; concentrate and straw were offered ad libitum. Mild (MD): calves were fed only MR (d -4 to -1) as described for CT, and on d -1 calves were subjected to a 9-h feed withdrawal. Moderate (MO): calves were fed only MR (d -4 to -1) as described for CT and on d -1 subjected to a 19-h feed withdrawal. Severe (SV): calves were fed only 2.5 L of a rehydrating solution twice daily (d -4 to -1) and on d -1 subjected to a 19-h feed withdrawal. From d 0 to d 42 (weaning) all calves were fed the same feeding program (MR, concentrate, and straw ad libitum). Results showed that BW was greater for the CT treatment compared with the others from d 0 to d 7, whereas BW of SV was lesser compared with the others from d -1 to d 7. No differences among treatments were observed at weaning. At d 2 concentrate intakes of MD, MO, and SV were lesser compared with CT. By d 4, concentrate intake of SV was similar to that for CT and greater than MD and MO. Similarly to BW, no differences in concentrate intake among treatments were observed at weaning on d 42 of the study. At d -1 for SV and d 0 in all restricted calves, serum glucose concentration was lesser compared with CT. At d -1 and 0, nonesterified fatty acids and BHB serum concentrations were greater in the SV calves compared with the other treatments. By d 2, serum concentrations of nonesterified fatty acids, BHB, and glucose were restored to CT levels. At d -1 serum citrulline concentration was lesser in SV and greater in MD calves. The CT calves had lower serum concentrations of Cr-EDTA (d -1 and d 0), lactulose (d 0), and d-mannitol (d 0) compared with the other restricted calves. Results showed that degree of dietary restriction, type of liquid diet (MR or rehydrating solution), and fasting hours (9 vs. 19 h) affected calves' BW, concentrate intake, and serum concentration of markers indicative of energy status and gastrointestinal permeability.

322 Impact of Feed Restriction and Fasting Suffered in Assembly Centers and Transportation on Energy Balance and Gut Permeability in Unweaned Angus-holstein Calves

Abstract Twenty unweaned Angus-Holstein calves (44.1 ± 2.0 kg; 14.7 ± 0.63 d) were used to evaluate the effects of feed restriction and fasting on energy balance (serum concentration of glucose, BHBA, and NEFA), and intestinal permeability (serum concentration of citrulline, Cr-EDTA, lactulose, and D-mannitol). Calves were randomly assigned to 1 of 4 treatments that simulated assembly center management and transportation; Control (CT; n = 5): from d-4 to -1, 2.5 L of milk replacer (MR) twice daily, concentrate and straw ad-libitum; Mild (MD; n = 5): only MR (d-4 to -1) as described for CT, and on d-1 feed withdrawal for 9 h; Moderate (MO; n = 5): only MR as described for CT and on d-1 feed withdrawal for 19 h; and Severe (SV; n = 5): only 2.5 L of a hydrate solution (HS) twice daily (d -4 to -1) on d-1 feed withdrawal for 19 h. From d 0 to day 7 all calves were fed MR, concentrate, and straw ad-libitum. Data were analyzed using mixed models with repeated measures. At d -1 for SV and d 0 in all restricted calves (MD, MO, SV), serum glucose concentration was lesser (P < 0.01) compared with CT. At d 0 NEFA and BHBA serum concentrations increased (P < 0.01) in SV calves compared with the other treatments. Serum citrulline concentration (P < 0.05) was lower for SV on d -1 and greater for CT on d 2 compared with other treatments. CT calves had the lesser concentration of Cr-EDTA (d -1 and d 0, P =0.04), lactulose (d 0, P =0.02), and D-mannitol (d 0, P =0.01) compared with MD, MO, and SV. The degree of dietary restriction, the type of liquid diet, and amount of fasting hours affected calves’ serum concentration of markers indicative of energy balance and gut permeability.

PSXII-4 Serum citrulline concentration of unweaned calves transported by road as a potential biomarker of gut functionality

Abstract In human’s serum citrulline concentration (SCC) have been proposed as a biomarker of small intestinal absorption. We hypothesize that the stress and feed restriction that unweaned calves suffer during transport impairs gut functionality reducing SCC. The aim of this study was to evaluate if road transport hours and adaptation period after arrival would affect SCC in unweaned calves. A total of 1,601 calves (3–4 wk of age; 65 ± 9 kg of BW) were transported with 8 trucks (n = 4 each journey): short transport (ST; < 9 h), and long transport with a rest stop proving feed and water to the calves (LT; > 9 h). A subset of 20 calves for each truck were sampled for SCC at arrival (t0), and 14 d after arrival (t14); in case of LT, also at arrival at the resting facility (t-1). SCC was analyzed using a commercial kit (intra- and inter-assay CV were 12.62% and 6.32%). Data was analyzed using a mixed model with journey hours and day as main effects, and calf and truck as random effects. SCC tended (P = 0.08) at t0 to be greater in LT (47.7 ± 3.39 mM) compared to ST (42.6 ± 2.46 mM). At t14 SCC increased in ST and LT calves; however, no differences were observed in SCC (55.9 ± 3.42 mM vs. 58.8 ± 2.52 mM for LT and ST, respectively). In LT calves rest stop did not affect SCC (43.2 ± 1.74 mM vs. 39.8 ± 1.76 mM for t-1 and t0, respectively), while at t14 (50.6 ± 1.86 mM) SCC was greater (P < 0.001) than t0 and t-1. The effect of transport type and evolution after transport on serum plasma citrulline concentrations may suggest that it’s a potential indicator of gut functionality in unweaned calves.

INTESTINAL DYSFUNCTION WITH ACUTE NECROTIZING PANCREATITIS

Objective: to substantiate and introduce clinically early diagnosis of intestinal dysfunction and algorithm of therapeutic measures for the treatment of disorders of intestinal barrier function during acute necrotizing pancreatitis. Material and methods. A prospective cohort study of 151 patients with acute necrotizing pancreatitis who were admitted to intensive care department was performed. Severity of intestinal dysfunction was determined according to the European Society of Intensive Care Medicine (ESICM) recommendations. Clinical, instrumental and laboratorial changes as well as intestinal metabolic function by serum citrulline concentrations in the blood plasma were studied. Efficacy of the suggested algorithm of intestinal barrier disorders treatment assuming differential application of therapeutic measures according to its severity is analyzed. Results and discussion. Disorders of gastrointestinal functions of 1st degree were found in 17.9 %, 2nd degree – 29.1 %, 3rd degree – 31.7 %, 4th degree – 8.6 % of patients with acute necrotizing pancreatitis. Significant correlation between severity of gastrointestinal disorders and serum citrulline concentration was established (r=0,743 р<0.05), its level below 12.5 µmol/l evidenced development of intestinal failure. Application of the developed algorithm of intestinal dysfunction correction enabled to reach recovery of 46 (30.7 %) patients without any surgery. Conclusion: Disorders of gastrointestinal functions in 35.8 % of patients with acute necrotizing pancreatitis are represented by feeding intolerance, in 33.2 % – by intestinal failure. Application of the algorithm of intestinal dysfunction correction improves efficacy of conservative treatment.

Use of serum citrulline concentrations from routine newborn screen as a biomarker for necrotizing enterocolitis.

Necrotizing enterocolitis (NEC), a leading cause of mortality and morbidity in preterm neonates, lacks a reliable biomarker. Citrulline is primarily produced by enterocytes and correlates with intestinal function. Serum citrulline concentration (CIT) is routinely measured in routine newborn screening (NBS). The purpose of the study is to test if CIT from NBS may predict the occurrence of NEC and whether it correlates with the time to full feeds (TTFF) and length of stay (LOS), serving as a biomarker of NEC and intestinal health. In a retrospective case control study conducted on neonates with gestational age of 26-32weeks, we compared CIT levels between cases (neonates with NEC) and controls (next-born neonate). NBS was collected within first 24h, at day5 and when the neonates achieved full feeds and were compared using non-parametric tests. There was no difference in CIT between the controls and cases on day1 [11.42 (7.42-14.84 vs. 11.93 (6.85-18.8)µmol/L, p = 0.55], on day5 [11.99 (7.99-16.55) vs. 13.70 (7.42-26.83)µmol/L, p = 0.05], or at full feeds [14.86 (6.85-25.69) vs. 15.7 (7.42-26.26)µmol/L, p = 0.87]. CIT on day1 did not correlate with TTFF (r = 0.08, p = 0.53) or LOS (r = 0.23, p = 0.06), respectively). CIT from routine NBS does not serve as a biomarker to predict NEC in preterm neonates.

DISORDERS OF GASTORINTESTINAL TRACT WITH ACUTE NECROTIZING PANCREATITIS

Objective: to establish changes of intestinal functions, including absorbing and metabolic, and their influence on complications development during phases of acute necrotizing pancreatitis. Material and methods. A prospective observational cohort study of 151 patients with acute necrotizing pancreatitis which were admitted to intensive care department was conducted. Severity of intestinal dysfunction was determined according to European Society of Intensive Care Medicine (ESICM) Recommendations. Clinical and laboratory changes as well as plasma citrulline concentrations were studied. Results and discussion. Disorders of gastrointestinal functions of 1st grade were found in 17.9%, 2nd grade – 29.1%, 3rd grade – 31.7%, 4th grade – 8.6% of patients with acute necrotizing pancreatitis. Serum citrulline concentration below 12.5 µmol/l enabled to diagnose development of intestinal failure. It was established by multivariate logistic regression that respiratory, cardio-vascular, renal and intestinal failure were independent mortality factors. Conclusions: Disorders of gastrointestinal functions in 35.8% of patients with acute necrotizing pancreatitis are represented by feeding intolerance, in 33.2% - by intestinal failure. Plasma citrulline concentration enables to diagnose development of intestinal failure with high sensitivity and specificity.

Determining optimal therapy of dogs with chronic enteropathy by measurement of serum citrulline.

BackgroundSerum concentration of citrulline is a useful biomarker in human intestinal disease and indicates globally reduced enterocyte mass and absorptive function in various disease states.ObjectivesTo determine whether serum citrulline concentration is a biomarker in chronic enteropathy (CE) in dogs, to provide useful information regarding optimal treatment or to predict outcome.AnimalsSeventy‐four dogs with CE and 83 breed‐ and age‐matched hospital controls with no clinical signs of intestinal disease.MethodsRetrospective study. Outcome was determined and dogs were categorized by response to treatment as having food‐responsive enteropathy (FRE), antibiotic‐responsive diarrhea (ARD), or idiopathic inflammatory bowel disease (IBD). Disease severity was quantified by the CIBDAI scoring index.ResultsSerum citrulline concentration did not differ between dogs with CE (median, 8.4 µg/mL, 5th‐95th percentile 2.0‐19.6) and controls (median, 8.1 µg/mL, 5th‐95th percentile 2.2‐19.7, P = .91). Serum citrulline concentration was similar between dogs with FRE (median, 9.1 µg/mL, 5th‐95th percentile 2.0‐18.9), ARD (median, 13.0 µg/mL, 5th‐95th percentile 1.6‐19.2), IBD (median, 8.4 µg/mL, 5th‐95th percentile 2.1‐21.0; P = .91). Serum citrulline did not correlate to CIBDAI or to serum albumin concentration.Conclusions and Clinical ImportanceIn our study, serum citrulline concentration was not associated with efficacy of treatment or outcome in dogs with CE.

Intestinal Oxygenotherapy of Critical Conditions

The latent or mist diagnosed dysfunction of the small intestine is a common disorder in critically ill patients. Intestinal oxygenotherapy is one of the alternative ways to normalize the coordinated activity of the smooth muscles of the digestive tract. Purpose of the study. To determine the effect of intestinal oxygenotherapy in patients with enteropathies of critical conditions on the dynamics of biomarkers of the intestinal wall permeability and ischemia. Materials and methods. An open prospective descriptive study of 12 critically ill patients (7 adults, 5 children) with multiple organ failure and evident or saspected dysfunction of the gastrointestinal tract. Pediatric patients included children with congenital heart disease who underwent open-heart surgery for the purpose of radical or palliative correction. Results. Complications related to the intestinal oxygenotherapy were not observed. On the contrary, its use in children coincided with the positive clinical dynamics: elimination of intestinal paresis, normalization of digestion of enteral nutrition. However, it is difficult to interpret the results unambiguously. Serum citrulline concentration in children is an objective marker of the functional state of the gastrointestinal tract: in the vast majority of the control points its level was 20 μmol/l (up to 80 μmol/l). No correlation between serum citrulline and I-FABP concentrations in adults was found. Conclusion. Intestinal oxygenotherapy is a promising therapeutic technique for prevention and correction of enteropathies. The method may appear especially effective in treatment of anaerobic (i.e. Cl. defficile-assosiated colitis) infection. The diagnostic value of plasma citrulline and I-FABP concentrations needs further confirmation.

Serum citrulline levels as a marker of enterocyte function in patients after allogeneic hematopoietic stem cells transplantation – a pilot study

BackgroundCitrulline is an amino acid produced by enterocytes. Serum citrulline concentration has been proposed as a marker of enterocyte mass and function. Our study focused on evaluation of citrulline levels in patients with diarrhea related to toxic intestinal damage (mucositis), intestinal graft versus host disease (GVHD), and other etiology of diarrhea (e.g., dysmicrobia) after allogeneic stem cells transplantation (SCT).Material/MethodsThis was a prospective study in 11 adults (18 blood samples) with diarrhea developed after allogeneic SCT in 4/2011–1/2012 compared to twenty healthy control samples.ResultsThe median (interquartile range) of citrulline levels was significantly lower in the transplanted patients group compared to healthy controls: 9.3 (3.62–15.38) vs. 33.3 (26.82–36.23) μmol/L, p<0.0001. The median values of citrulline in patients with post-transplant toxic intestinal mucositis (n=8, days 1–22 post-transplant) vs. intestinal GVHD (n=7, day 43–142) vs. other etiology of diarrhea (e.g., dysmicrobia) (n=3, day 120–127) were: 9.55 (2.95–12.03) vs. 5 (3.85–9.05) vs. 15.6 (15.45–18.3) μmol/L resp. Serum citrulline levels were significantly higher in other (eg, dysmicrobic) etiology of diarrhea in comparison with mucositis (p=0.0336) and GVHD (p=0.0152).ConclusionsCitrulline levels are very low shortly after the myeloablative FLU/MEL or BuCY2 conditioning allogeneic SCT due to the toxic intestinal damage. Significantly low levels of citrulline were also in patients with intestinal GVHD later on. Other observations in larger groups of patients are necessary before any specific recommendation for citrulline levels monitoring in intestinal GVHD can be made.

Low Serum Citrulline Concentration Correlates With Catheter‐Related Bloodstream Infections in Children With Intestinal Failure

Serum citrulline concentration is used as a biomarker of enterocyte mass and enteral tolerance, and low serum concentrations are correlated with bacteremia in immunosuppressed adults undergoing hematopoietic stem cell transplant. The authors sought to determine if citrulline was associated with the development of catheter-related bloodstream infections (CRBSIs) in children with intestinal failure. Data were reviewed from 66 children treated in a multidisciplinary intestinal rehabilitation program, who had serum concentration citrulline measured between January 2007 and August 2009. All patients had a diagnosis of intestinal failure requiring parenteral nutrition (PN) support. Exclusion criteria included central venous catheter in situ <30 days, creatinine clearance <20 mL/minute, or a history of organ transplant/immunosuppression. A total of 15 patients were excluded because of the above criteria. In this cohort of 51 patients, 26 (51%) developed CRBSIs. Both groups were similar in terms of gestational age, diagnosis, nutrition status, and biochemical liver function tests. The mean (± standard deviation [SD]) minimum serum citrulline concentration was significantly lower in patients who developed CRBSIs (6.7 ± 4.6 µmol/L) than in those who did not (11.3 ± 6.4 µmol/L, P = .004). Multivariate logistic regression analysis identified lower minimum serum citrulline concentration and longer central venous catheter duration as independently associated with CRBSI (P = .003 and P = .038, respectively). Low serum citrulline concentration and longer central venous catheter time are independently associated with CRBSI in children with intestinal failure. Serum citrulline concentration may be a useful biomarker to identify patients with intestinal failure who are at high risk of developing a CRBSI.

Is serum citrulline measurement clinically useful in coeliac disease?

Citrulline (CIT), a non-protein amino acid in circulating blood, is almost exclusively contained in the enterocytes of small bowel mucosa and may represent a reliable marker of functioning enterocyte mass. The aim of this study was to evaluate the clinical utility of measuring serum citrulline levels in a group of patients affected by coeliac disease (CD). Fifty healthy volunteers, 21 patients with untreated coeliac disease and 6 patients with refractory coeliac disease took part in the study. Serum citrulline levels and duodenal lesions were evaluated at the time of diagnosis, and after at least 24 months of gluten-free diet. Serum citrulline concentrations were determined by ion exchange chromatography. In comparison to healthy volunteers, serum citrulline concentrations were significantly lower in untreated and refractory coeliac disease patients. No significant difference was found between untreated and refractory coeliac disease patients and between patients with different patterns of clinical presentation or various degrees of duodenal lesions. After a gluten-free diet, the mean of serum citrulline concentration was increased in all but one patient. Although, as expected, serum citrulline levels turned out to be low in coeliac disease, the clinical utility of their measurement is, at least, questionable in this condition.

Serum citrulline: a potential marker for intestinal epithelial mass and absorption capacity in short bowel syndrome patients

To investigate the potential role of serum citrulline level in evaluating the intestinal absorptive area and capacity in patients with short bowel syndrome (SBS). Serum citrulline concentration was determined using high performance liquid chromatography (HPLC) in SBS patients (n=22) and healthy controls (n=33). In SBS patients, the remnant small bowel lengths and diameters were measured by radiography, and their 5- hour urine D- xylose excretion and intestinal protein absorption were also determined. The correlationship of serum citrulline level with remnant small bowel length, surface area, protein and D- xylose absorption was analyzed. The 6 patients receiving intestinal rehabilitative therapy, serum citrulline level, protein and D- xylose absorption after therapy were also measured. Serum citrulline level of SBS patients was significantly lower than that of healthy controls [(5.94+/- 2.65) vs [(16.87 +/- 5.97) micromol/L, P < 0.01]. In SBS patients, serum citrulline was positively correlated with remnant small bowel length and surface area (r=0.82 and r=0.86 respectively). There was also a significant correlationship of serum citrulline level with 5- hour D- xylose excretion (r=0.56) and intestinal protein absorption (r=0.48). Serum citrulline, 5- hour D- xylose excretion and intestinal protein absorption were all significantly raised in patients after rehabilitative therapy, although no correlation of increasing percentage was found among above three parameters. Serum citrulline concentration is positively correlated with intestinal absorptive area and capacity in SBS patients. It is a potential marker for evaluating the severity of intestinal failure and the efficacy of rehabilitative therapy in short bowel patients.

Monitoring myeloablative therapy‐induced small bowel toxicity by serum citrulline concentration

Intestinal mucositis is an important cause of cancer treatment-related morbidity and mortality, carrying a serious economic burden. Currently, objective parameters are lacking that would enable the monitoring of gut damage in routine clinical practice, thus hindering the development of clinical studies designed to investigate potential new strategies aimed at reducing or preventing this side effect. The authors investigated the characteristics of serum citrulline concentration compared with sugar permeability tests with respect to its use as a marker for cancer treatment-induced small bowel injury. In this prospective study, 10 patients with hematologic malignancies who were receiving myeloablative therapy had gut toxicity assessed with sugar permeability tests. Serum citrulline concentrations also were determined using archival serum samples. The association between both parameters and their respective characteristics were analyzed and compared with data from the literature. Sensitivity and specificity were better for the citrulline assay compared with sugar permeability tests. Maximum gut damage assessed with the citrulline assay was observed 1-2 weeks earlier compared with the sugar permeability test. Similarly, citrulline indicated recovery of gut damage at 3 weeks after transplantation, whereas most sugar permeability tests remained abnormal. The simplicity of the method, the low costs, and the lack of drawbacks to the method make the citrulline assay the first choice for measuring and monitoring treatment-related gut damage and provides an objective parameter for cancer treatment-related gut toxicity.

474 oral Monitoring myelo-ablative therapy induced small bowel toxicity by serum citrulline concentration. A comparison with sugar permeability tests

474 oral Monitoring myelo-ablative therapy induced small bowel toxicity by serum citrulline concentration. A comparison with sugar permeability tests

Effect of arginine on cyclosporine-induced systemic hypertension after cardiac transplantation in the young

R publications support many different etiologies for cyclosporine-induced hypertension, but none have been definitive. Several studies have demonstrated impaired endothelium-dependent vasodilation in arteries isolated from cyclosporine-treated animals,1,2 and in human peripheral arteries exposed to cyclosporine in vitro.3 Furthermore, studies suggest that long-term cyclosporine treatment suppresses synthesis of nitric oxide (NO), a potent endogenous vasodilator.4–6 Pretreatment with L-arginine, the amino acid precursor for NO, preserves endothelium-dependent vascular relaxation and prevents systemic hypertension in cyclosporine-treated animals.7,8 Therefore, we hypothesized that cyclosporine-induced hypertension is associated with an altered L-arginine/NO pathway in vivo. To evaluate this hypothesis, we studied the acute effects of intravenous L-arginine infusion on blood pressure (BP), heart rate, left ventricular (LV) function, and NO production in young heart transplant patients receiving cyclosporine. • • • The study population consisted of 9 young cardiac transplant patients and 5 healthy volunteers. All patients were receiving cyclosporine as part of their immunosuppressive regimen, in addition to an antihypertensive medication (either a calcium channel antagonist or an angiotensin-converting enzyme inhibitor). No control subject was taking any medications at the time of the study. Patient and parental permission were obtained for inclusion in the study. The research protocol was approved by The University of Michigan Medical School Institutional Review Board for Human Subject Research. Heart transplant patients were studied in the cardiac catheterization laboratory after routine cardiac catheterization and endomyocardial biopsy (Figure 1). All patients were awake and alert; only local anesthetic was used for the catheterization. Control subjects were also studied in the cardiac catheterization laboratory. All subjects fasted for $4 hours before the study, and all subjects remained in the supine position throughout the protocol. Baseline noninvasive BP (Dinamap) and heart rate were determined. Following baseline measurements, all subjects received a continuous intravenous infusion of 10% Larginine hydrochloride (total dose 500 mg/kg, maximum of 30 g).9,10 The pharmacokinetics of intravenous arginine have been debated in the literature. One recent study showed a biphasic elimination pattern after intravenous administration,11 whereas others have found the pharmacokinetics to be constant in the range of infusion rates used in our study.9 Depending on the study, the half-life of arginine for the dose used in this protocol ranged from 17.8 6 1.9 to 42 6 2 minutes. In our study, arginine infusion was given over 30 minutes to achieve a steady state, and then discontinued, followed by a 30-minute recovery period. NO is synthesized in biologic systems by the enzyme NO synthase, which acts on L-arginine and molecular oxygen to produce NO and citrulline in a stoichiometric fashion. NO is rapidly degraded and is difficult to quantitate directly. Therefore, as an indirect measure of NO production, we measured serum citrulline concentrations by high-performance liquid chromatography, at baseline, 30, and 60 minutes. To determine LV function, either LV shortening fraction (measured by M-mode echocardiography in the parasternal short-axis view), or LV ejection fraction (measured by Simpson’s method from 2-dimensional echocardiography in the apical 4-chamber view) was obtained in 6 of the 9 transplant patients at baseline and at 30 minutes. Echocardiograms were not available in the control patients. Baseline, 30-minute (“arginine infusion”), and 60minute (“recovery”) systolic BP, diastolic BP, mean arterial BP, and serum citrulline concentration are reported for transplant patients and control subjects (expressed as mean 6 SD). Differences between patients and controls were tested using a Student’s t test. Differences in the same patient compared at baseline, with arginine infusion, and recovery were tested using a paired Student’s t test. • • • Baseline characteristics as well as experimental data on all subjects are presented in Table 1. Mean age of the cardiac transplant patients was 20 years (range 13 to 26) and mean systolic blood pressure was 130 mm Hg (range 103 to 147). Mean age of the control subjects was 34 years (range 28 to 38) and mean systolic blood pressure was 129 mm Hg (range 122 to 143). There was no significant difference in baseline BP From the Departments of Pediatrics and Communicable Diseases, and Physiology, University of Michigan Medical Center, Ann Arbor, Michigan. This study was supported by grants from the American Heart Association, Michigan Affiliate (grant #07FW978), and the General Clinical Research Center of the University of Michigan (NIH grant #M01-RR00042). Dr. Gomez’s address is: University of Michigan Congenital Heart Center, University of Michigan, F1310 MCHC, Box 0204, 1500 E. Medical Center Drive, Ann Arbor, Michigan 481090204. E-mail: cago@umich.edu. Manuscript received May 30, 2000; revised manuscript received and accepted October 17, 2000.

Correction of ornithine transcarbamylase (OTC) deficiency in spf-ash mice by introduction of rat OTC gene

We introduced rat ornithine transcarbumylase (OTC) gene into OTC-deficient spf-ash mice by mating spf-ash heterozygotes with transgenic mice which carried recombinant DNA composed of 1.3 kb of the 5′ flanking region of the gene fused onto rat OTC cDNA. The liver OTC activity of hemizygous spf-ash mice which carried the transgene was about twice that of nontransgenic spf-ash mice, and the small intestinal OTC activity was 6 times higher; the values being 12% and 27% of the control levels, respectively. The transgenic spf-ash mice showed normal hair growth without sparse, fur, nearly normalized urinary orotic acid excretion and normalized serum citrulline concentration.