High-grade Vesicoureteral Reflux in Patients With Anorectal Malformation From the ARM-Net Registry: Is Our Screening Sufficient?

BACKGROUND

Vesico-ureteral reflux (VUR) is a common associated urological anomaly in anorectal malformation (ARM)-patients. High-grade VUR requires antibiotic prophylaxis to prevent urinary tract infections (UTI's), renal scarring and -failure. The exact prevalence of high-grade VUR in ARM patients is unknown. Hence, the aim of this study was determining the incidence of high-grade VUR in ARM-patients, and its associated risk factors.

METHODS

A multicenter retrospective cohort study was performed using the ARM-Net registry, including data from 34 centers. Patient characteristics, screening for and presence of renal anomalies and VUR, sacral and spinal anomalies, and sacral ratio were registered. Phenotypes of ARM were grouped according to their complexity in complex and less complex. Multivariable analyses were performed to detect independent risk factors for high-grade (grade III-V) VUR.

RESULTS

This study included 2502 patients (50 % female). Renal screening was performed in 2250 patients (90 %), of whom 648 (29 %) had a renal anomaly documented. VUR-screening was performed in 789 patients (32 %), establishing high-grade VUR in 150 (19 %). In patients with a normal renal screening, high-grade VUR was still present in 10 % of patients. Independent risk factors for presence of high-grade VUR were a complex ARM (OR 2.6, 95 %CI 1.6-4.3), and any renal anomaly (OR 3.3, 95 %CI 2.1-5.3).

CONCLUSIONS

Although renal screening is performed in the vast majority of patients, only 32 % underwent VUR-screening. Complex ARM and any renal anomaly were independent risk factors for high-grade VUR. Remarkably, 10 % had high-grade VUR despite normal renal screening. Therefore, VUR-screening seems indicated in all ARM patients regardless of renal screening results, to prevent sequelae such as UTI's, renal scarring and ultimately renal failure.

TYPE OF STUDY

Observational Cohort-Study.

LEVEL OF EVIDENCE

III.

Development of a posterior sagittal anorectal surgical teaching model

Background

An Anorectal Malformation (ARM) is a rare congenital malformation, which requires proper correction to ensure the best long-term prognosis. These procedures are relatively infrequent and complex, in which a structured approach is important. Therefore, training on an affordable model could be beneficial.

Methods

A low-cost ARM model was developed. The base was reusable and the perineal body disposable. Both expert pediatric surgeons (Experts) and residents/fellows (Target group) were recruited for this study. After testing the model, they completed a questionnaire regarding the realism and didactic value of the model, using a 5-point Likert scale.

Results

Forty-four participants were recruited (Target group n = 20, Experts n = 24). The model has high mean scores of 3.8–4.4 for the total group and even higher on several aspects by the Target group. The experts regarded the haptics and manipulation of the fistula less realistic than the Target group (3.7 versus 4.3, p = 0.021 and 4.2 versus 4.6, p = 0.047). It was considered to be a very good training tool (mean 4.3), without significant differences between the groups.

Conclusions

These results show general consensus that this model is a potent training tool for the component steps of the repair of an ARM with recto-perineal fistula by sagittal approach.

Long-term functional outcomes and quality of life in patients with Hirschsprung's disease

BACKGROUND

It is unclear whether functional outcomes improve or deteriorate with age following surgery for Hirschsprung's disease. The aim of this cross-sectional study was to determine the long-term functional outcomes and quality of life (QoL) in patients with Hirschsprung's disease.

METHODS

Patients with pathologically proven Hirschsprung's disease older than 7 years were included. Patients with a permanent stoma or intellectual disability were excluded. Functional outcomes were assessed according to the Rome IV criteria using the Defaecation and Faecal Continence questionnaire. QoL was assessed by means of the Child Health Questionnaire Child Form 87 or World Health Organization Quality of Life questionnaire 100. Reference data from healthy controls were available for comparison.

RESULTS

Of 619 patients invited, 346 (55·9 per cent) responded, with a median age of 18 (range 8-45) years. The prevalence of constipation was comparable in paediatric and adult patients (both 22·0 per cent), and in patients and controls. Compared with controls, adults with Hirschsprung's disease significantly more often experienced straining (50·3 versus 36·1 per cent; P = 0·011) and incomplete evacuation (47·4 versus 27·2 per cent; P < 0·001). The prevalence of faecal incontinence, most commonly soiling, was lower in adults than children with Hirschsprung's disease (16·8 versus 37·6 per cent; P < 0·001), but remained higher than in controls (16·8 versus 6·1 per cent; P = 0·003). Patients with poor functional outcomes scored significantly lower in several QoL domains.

CONCLUSION

This study has shown that functional outcomes are better in adults than children, but symptoms of constipation and soiling persist in a substantial group of adults with Hirschsprung's disease. The persistence of defaecation problems is an indication that continuous care is necessary in this specific group of patients.

Long-term outcome and quality of life in patients with total colonic aganglionosis in the Netherlands

AIM

Total colonic aganglionosis (TCA) is a severe form of Hirschsprung's disease (HD) associated with a high morbidity. This study assessed long-term functional outcome and quality of life (QoL) of patients with TCA in a national consecutive cohort.

METHODS

Surgical and demographic characteristics in the medical records of all patients (n = 53) diagnosed with TCA between 1995 and 2015 were reviewed. Functional outcome of all nonsyndromal patients, aged ≥ 4 years (n = 35), was assessed using a questionnaire and in medical records. Generic and disease-specific QoL were assessed using standardized validated questionnaires.

RESULTS

Of 35 patients eligible for follow-up, 18 (51%) responded to the questionnaires. They were aged 4-19 years. A Duhamel procedure was performed in 67% of these patients and a Rehbein procedure was performed in 33%. In the questionnaire, 65% of the patients reported constipation, 47% faecal incontinence and 53% soiling. Moreover, 18% of patients used bowel management (flushing or laxatives) and 29% had an adapted diet only. Children and adolescents with TCA had worse perception of their general health and were more limited by bodily pain and discomfort compared with healthy peers. Their quality of life is influenced most by frequent complaints of diarrhoea and other physical symptoms.

CONCLUSION

Children and adolescents with TCA report lower health-related QoL compared with healthy peers, especially in the physical domain. We suggest standardized follow-up and prospective longitudinal future research on functionality and QoL of these patients.

Redo pull-through surgery in Hirschsprung disease: Short-term clinical outcome

INTRODUCTION

Although surgery is effective in most patients with Hirschsprung disease (HD), some have persistent obstructive symptoms. Additional medical treatment is generally sufficient, but a small fraction of these patients needs secondary surgery. Series on redo surgery are scarce. Aim of this study is to evaluate complications and clinical outcome of patients in need of redo surgery for HD.

MATERIALS AND METHODS

Sixteen patients underwent redo endorectal pull-through surgery in our center between 2007 and 2015. Medical records were reviewed and demographics, indication for redo surgery, surgical procedures, complications, and clinical outcome were scored.

RESULTS

The median age at the time of redo was 4.6years (range: 2months-21years). Median follow-up after redo was 3years (range: 9months-7years). Before redo surgery, all patients (100%) had obstructive symptoms, one patient had recurrent enterocolitis, and four patients were fecally incontinent despite adequate attempts of bowel management. Surgical procedure consisted of a transanal endorectal pull-through (TERPT) in all patients, with additional laparotomy in 7 (44%) and protective stoma in 8 patients (50%). Complications within 30days after redo surgery were anastomotic dehiscence (3; 19%), wound abscess (2; 13%), rectovaginal fistula (1; 7%) or enterocutaneous fistula (1; 7%). During follow-up, nine patients needed additional surgery, mainly to close the stoma. At final follow-up there were no patients with stenosis, obstructive symptoms, remaining rectovaginal fistula, or small bowel obstruction. Only one patient experienced enterocolitis. Six patients (43%) reported soiling or fecal incontinence.

CONCLUSION

TERPT for redo surgery for HD is effective in resolving sustained severe obstructive symptoms after primary surgery, but the outcome is complicated by a relatively high rate of soiling and fecal incontinence.

Duhamel versus transanal endorectal pull through (TERPT) for the surgical treatment of Hirschsprung's disease

For the surgical treatment of Hirschsprung's disease, several surgical techniques are used to resect the distal aganglionic colon. Two frequently used techniques are the Duhamel procedure and the transanal endorectal pull-through procedure. During the '8th Pediatric Colorectal Course' in Nijmegen, November 2015, a workshop was organized to share experiences of both techniques by several experts in the field and to discuss (long term) outcomes. Specifically, the objective of the meeting was to discuss the main controversies in relation to the technical execution of both procedures in order to make an initial assessment of the limitations of available evidence for clinical decision-making and to formulate a set of preliminary recommendations for current clinical care and future research.

Outcome in anorectal malformation type rectovesical fistula: a nationwide cohort study in The Netherlands

PURPOSE

Outcomes of patients with an ARM-type rectovesical fistula are scarcely reported in medical literature. This study evaluates associated congenital anomalies and long-term colorectal and urological outcome in this group of ARM-patients.

METHODS

A retrospective Dutch cohort study on patients treated between 1983 and 2014 was performed. Associated congenital anomalies were documented, and colorectal and urological outcome recorded at five and ten years of follow-up.

RESULTS

Eighteen patients were included, with a mean follow-up of 10.8years. Associated congenital anomalies were observed in 89% of the patients, 61% considered a VACTERL-association. Total sacral agenesis was present in 17% of our patients. At five and ten years follow-up voluntary bowel movements were described in 80% and 50%, constipation in 80% and 87%, and soiling in 42% and 63% of the patients, respectively. Bowel management was needed in 90% and one patient had a definitive colostomy. PSARP was the surgical reconstructive procedure in 83%. Urological outcome showed 14 patients (81%) to be continent. No kidney transplantations were needed.

CONCLUSION

In our national cohort of ARM-patients type rectovesical fistula that included a significant proportion of patients with major sacral anomalies, the vast majority remained reliant on bowel management to be clean after ten years follow-up, despite "modern" PSARP-repair. Continence for urine is achieved in the majority of patients, and end-stage kidney failure is rare.

Cloacal malformation patients report similar quality of life as female patients with less complex anorectal malformations

PURPOSE

Cloacal malformations are the most complex type of anorectal malformation in females. This study aimed to report quality of life (QoL) of patients with a cloacal malformation for the first time in literature.

MATERIALS AND METHODS

Female patients with an anorectal malformation participating in a follow-up program for congenital malformation survivors aged 5 or older were eligible for this study. QoL was assessed with the PedsQL™ 4.0 inventory. Scores of patients with a cloacal malformation (CM) were compared with those of female patients with rectoperineal or rectovestibular fistulas (RP/RV) and with reference data.

RESULTS

A total of 59 patients (67% response rate; 13 patients with cloacal malformation) were included, QoL was assessed by patient self-report at median age of 12years (8-13), and by parent proxy-report at median age of 8years (5-12). There were no differences between groups regarding the presence of associated anomalies, with also no differences regarding anomalies in the urinary tract (CM vs. RP/RV=31% vs. 15%, p=0.237). Scores of the cloacal malformations group were similar to those of the comparison group, except the proxy-reported scores on school functioning (60.0 vs. 80.0, p=0.003). Proxy-reported scores of cloacal malformation patients were significantly lower than reference values on total QoL-score, psychosocial health, and emotional and school performance. Patients (irrespective of type of ARM) who suffered from fecal soiling reported significantly lower scores with regard to psychosocial health (71.7 vs. 81.7, p=0.034) and its subscale school performance (65.0 vs. 80.0, p<0.001). QoL-scores reported by cloacal malformation patients did not differ significantly from the reference values of the healthy population. Parents of cloacal malformation patients reported significantly lower total QoL, emotional and school performances, as well as a lower general psychosocial health for their children relative to reference data of healthy children.

CONCLUSION

Patients with cloacal malformations and females with less complex anorectal malformations report similar QoL. Parents of cloacal malformation patients report more problems on several psychosocial domains relative to the healthy reference group. To monitor these matters, long-term follow-up protocols should contain multidisciplinary treatment including periodical assessment of psychosocial well-being.

Postoperative complications after reconstructive surgery for cloacal malformations: a systematic review

The repair of cloacal malformations is most often performed using a posterior sagittal anorecto-vagino-urethroplasty (PSARVUP) or total urogenital mobilization (TUM) with or without laparotomy. The aim of this study was to systematically review the frequency and type of postoperative complication seen after cloacal repair as reported in the literature. A systematic literature search was conducted according to preferred reporting items for systematic reviews and meta-analyses guidelines (PRISMA). Eight records were eligible for this study which were qualitatively analyzed according to the Rangel score. Overall complication rates reported in included studies ranged from 0 to 57 %. After meta-analysis of data, postoperative complications were seen in 99 of 327 patients (30 %). The most common reported complications were recurrent or persistent fistula (n = 29, 10 %) and rectal prolapse (n = 27, 10 %). In the PSARVUP group, the complication rate was 40 % and in the TUM group 30 % (p = 0.205). This systematic review shows that postoperative complications after cloacal repair are seen in 30 % of the patients. The complication rates after PSARVUP and TUM were not significantly different. Standardization in reporting of surgical complications would inform further development of surgical approaches. Other techniques aiming to lower postoperative complication rates may also deserve consideration.

The influence of anorectal malformations on fertility: a systematic review

PURPOSE

This systematic review aims to give an overview of available evidence concerning the influence of anorectal malformations (ARM) on fertility.

METHODS

We conducted a search in PubMed, EMBASE and Cochrane Library conformed to the PRISMA standards. All studies reporting on fertility and ARM were included.

RESULTS

2,905 studies were identified. Based on title, abstract and full text, nine articles on 429 patients remained to answer the research question. Childbirth rate was the only reported outcome parameter to describe fertility. An overall childbirth rate of 27 % (range 0-57 %) was found. Mean age at time of study ranged from 23 to 35 years. There was no statistical significant difference in childbirth rate between female and male patients, based on seven studies (p = 0.45). Patients with a more complex type of ARM (imperforated anus without fistula, rectourethral bulbar and prostatic fistulas, rectobladderneck fistulas and cloacal malformations) had a lower childbirth rate compared to healthy controls, whereas in patients with a less complex ARM (rectoperineal or rectovestibular fistula) the childbirth rate was similar to healthy controls. Patients with a more complex type of ARM had a significant lower childbirth rate than patients with a less complex type of ARM (18 vs 47 %, respectively) (p = 0.0001). When further dividing these patients by gender, this difference was only seen in female patients (p = 0.04).

CONCLUSION

In patients with a more complex type of ARM a lower childbirth rate was found compared to healthy controls and patients with a less complex type of ARM. The latter was only seen in female patients. However, conclusions concerning fertility in ARM patients have to be taken with caution due to limited quality of the studies. Further investigation is recommended.

Anorectal malformations and pregnancy-related disorders: a registry-based case-control study in 17 European regions

OBJECTIVE

To identify pregnancy-related risk factors for different manifestations of congenital anorectal malformations (ARMs).

DESIGN

A population-based case-control study.

SETTING

Seventeen EUROCAT (European Surveillance of Congenital Anomalies) registries, 1980-2008.

POPULATION

The study population consisted of 1417 cases with ARM, including 648 cases of isolated ARM, 601 cases of ARM with additional congenital anomalies, and 168 cases of ARM-VACTERL (vertebral, anal, cardiac, tracheo-esophageal, renal, and limb defects), along with 13 371 controls with recognised syndromes or chromosomal abnormalities.

METHODS

Multiple logistic regression analyses were used to calculate adjusted odds ratios (ORs) for potential risk factors for ARM, such as fertility treatment, multiple pregnancy, primiparity, maternal illnesses during pregnancy, and pregnancy-related complications.

MAIN OUTCOME MEASURES

Adjusted ORs for pregnancy-related risk factors for ARM.

RESULTS

The ARM cases were more likely to be firstborn than the controls (OR 1.6, 95% CI 1.4-1.8). Fertility treatment and being one of twins or triplets seemed to increase the risk of ARM in cases with additional congenital anomalies or VACTERL (ORs ranging from 1.6 to 2.5). Maternal fever during pregnancy and pre-eclampsia were only associated with ARM when additional congenital anomalies were present (OR 3.9, 95% CI 1.3-11.6; OR 3.4, 95% CI 1.6-7.1, respectively), whereas maternal epilepsy during pregnancy resulted in a five-fold elevated risk of all manifestations of ARM (OR 5.1, 95% CI 1.7-15.6).

CONCLUSIONS

This large European study identified maternal epilepsy, fertility treatment, multiple pregnancy, primiparity, pre-eclampsia, and maternal fever during pregnancy as potential risk factors primarily for complex manifestations of ARM with additional congenital anomalies and VACTERL.

Severe gastrointestinal tract bleeding in a two-month-old infant due to congenital intrahepatic arterioportal fistula

A 2-month-old boy was referred for assessment of severe upper gastrointestinal tract bleeding and melena. On physical examination, a continuous murmur was heard over the right upper quadrant of the abdomen. A splenomegaly and dilated veins were also noted on the abdominal wall. Liver functions were normal. There was no history of trauma or jaundice. Doppler ultrasonography, magnetic resonance arteriography and angiography suggested the presence of an intrahepatic arteriovenous fistula between the phrenic artery and the portal vein. Management consisted of successful embolization by coiling of the phrenic artery. To our knowledge this is the first documented case report of a congenital fistula between the phrenic artery and the portal vein.

[Hemobilia as a complication of laparoscopic cholecystectomy]

A woman aged 38 displayed colicky pains and melaena two weeks after a laparoscopic cholecystectomy. The haemoglobin level was decreased, the serum hepatic enzyme levels were slightly increased. Diagnostic imaging examinations and finally, because of recurrent symptoms, an emergency laparotomy revealed a bleeding from a pseudoaneurysm of the proper hepatic artery next to the choledochus. The aneurysm was ligated. Seven months later the patient had no more symptoms. The possibility of haemobilia should be considered in every case of gastrointestinal bleeding after laparoscopic cholecystectomy.

Glutamine: the pivot of our nitrogen economy?

Glutamine serves as a shuttle of useful nontoxic nitrogen, supplying nitrogen from glutamine-producing (eg, muscle) to glutamine-consuming tissues. True production rates of glutamine are difficult to measure, but probably are less than 60 to 100 g/d for a 70-kg man. During catabolic stress increased amounts of glutamine are released from muscle, consisting of protein derived glutamine, newly synthesized glutamine, and glutamine losses from the intramuscular free pool. The large and rapid losses of free muscle glutamine are difficult to restore, presumably as a result of disturbances in the Na+ electrochemical gradient across the cell membrane. Whereas increased amounts of glutamine are released from muscle, glutamine consumption by the immune system (liver, spleen) also is enhanced. Thus, during catabolic stress changes occur in the flow of glutamine between organs. These changes are not necessarily reflected by alterations in the whole-body appearance rate of glutamine. In contrast with the gut, where glutamine is taken up in a concentration dependent manner, the immune system actively takes up glutamine despite decreased plasma concentrations. Supplementation with glutamine influences uptake by both the gut and the immune system, as evidenced by increased mucosal glutamine concentrations and gut glutathione production. There is evidence suggesting that this improves gut barrier function. Although the benefit of glutamine supplementation is most evident from experimental studies, clinical studies on the effect of glutamine do exist and suggest that glutamine supplementation has beneficial effects with regard to patient outcome.

[Cachexia in cancer: disturbances in the protein and aminoacid metabolism]

Cancer induced cachexia is characterized by complex changes in the intermediary metabolism. There is a raised basal metabolism with increased turnover of lipids, carbohydrates and proteins. In this altered metabolic milieu, protein catabolism occurs in peripheral tissue resulting in release of amino acids for the benefit of visceral organs. These as a rule increase in protein mass and also produce more plasma proteins. The amino acid glutamine plays a central part in this. It is released in large amounts from muscle tissue and is consumed to a high degree by visceral organs and immune cells. Although biochemically glutamine is not an essential amino acid, in cancer-induced cachexia it appears to be a 'conditionally' essential amino acid. Changes in the protein metabolism appear to be controlled by chronically increased neuroendocrine and inflammatory activity (exerted among other things by tumour necrosis factor alpha, interleukins 1 and 6 and catecholamines). Fundamental research, animal experiments and certain clinical trials show that the metabolism altered by these mediators can be corrected using hormonal preparations such as growth hormone, beta 2-adrenergic agonists and insulin. In the future it may conceivably be possible to correct the metabolic disturbance with drugs and the depletion of nutrients with specific nutritional supplements.

Effects in vivo of decreased plasma and intracellular muscle glutamine concentration on whole-body and hindquarter protein kinetics in rats

Glutamine is considered to be a 'conditionally' essential amino acid. During situations of severe stress like sepsis or after trauma there is a fall in plasma glutamine levels, enhanced glutamine turnover and intracellular muscle glutamine depletion. Under these conditions, decreased intramuscular glutamine concentration correlates with reduced rates of protein synthesis. It has therefore been hypothesized that intracellular muscle glutamine levels have a regulatory role in muscle protein turnover rates. Administration of the glutamine synthetase inhibitor methionine sulphoximine (MSO) was used to decrease glutamine levels in male Wistar rats. Immediately after the MSO treatment (t=0 h), and at t=6 h and t=12 h, rats received intraperitoneal injections (10 ml/100 g body weight) with glutamine (200 mM) to test whether this attenuated the fall in plasma and intracellular muscle glutamine. Control animals received alanine and saline after MSO treatment, while saline was also given to a group of normal rats. At t=18 h rats received a primed constant infusion of L-[2,6-3H]phenylalanine. A three-pool compartment tracer model was used to measure whole-body protein turnover and muscle protein kinetics. Administration of MSO resulted in a 40% decrease in plasma glutamine and a 60% decrease in intracellular muscle glutamine, both of which were successfully attenuated by glutamine infusions. The decreased intracellular muscle glutamine levels had no effect on whole-body protein turnover or muscle protein kinetics. Also, glutamine supplementation did not alter these parameters. Alanine supplementation increased both hindquarter protein synthesis and breakdown but the net balance of phenylalanine remained unchanged. In conclusion, our results show that decreased plasma and muscle glutamine levels have no effect on whole-body protein turnover or muscle protein kinetics. Therefore, it is unlikely that, in vivo, the intracellular muscle concentration of glutamine is a major regulating factor in muscle protein kinetics.

Cancer reduces the metabolic response of muscle to surgical stress in the rat

The metabolic response to surgical stress is characterized by muscle protein breakdown and mobilization of amino acids, e.g., glutamine, from peripheral tissue to visceral organs. Cancer is related to increased protein breakdown of muscle which may influence the normal metabolic response after surgery. The aim was to study the effects of cancer on postoperative peripheral muscle protein and glutamine turnover. Methylcholanthrene-induced sarcomas were implanted subcutaneously in female Lewis rats. Tumor-bearing rats were studied when the tumor was 5-15% of body weight. Control rats were sham implanted. Hysterectomy was performed in control and tumor-bearing rats as a standardized operative procedure. On the second postoperative day a primed constant infusion of para-aminohippuric acid, l-[2,6-3H]phenylalanine, and l-[3,4-3H]glutamine was given under ether anesthesia. At steady state, hindquarter muscle protein turnover and glutamine kinetics were determined in a three-compartment model. In control rats muscle protein synthesis almost doubled and protein breakdown increased threefold after hysterectomy, with concomitant increased outward amino acid membrane transport rates. Hysterectomy did not change protein synthesis or breakdown rates in tumor-bearing rats. Muscle glutamine production and membrane transport and release increased after hysterectomy in control rats. Tumor-bearing rats had depressed membrane transport rates and showed no surgical stress response related to muscle glutamine metabolism. The present study shows that surgical stress induces an increased mobilization of amino acids, e.g., glutamine, from muscle that does not occur in the cancer-bearing state. The reduced metabolic response to surgery in the cancer-bearing host may be of particular importance for the functioning of visceral organs, which use amino acids like glutamine at a high rate after trauma.

In vivo inter-organ protein metabolism of the splanchnic region and muscle during trauma, cancer and enteral nutrition

The study of protein kinetics has entered a new era by the recognition that whole body protein turnover only poorly reflects the true events occurring in several organs and with regard to the multitude of proteins present in the body. It is also increasingly recognized that the simultaneous synthesis and degradation of proteins is important in regulation and adaptation during several metabolic conditions like starvation, feeding, after trauma, and during exercise. Especially important is the recognition that the kinetics of individual proteins may change in opposite directions, thereby leading to fluxes of alpha-amino-nitrogen that serve to adapt to and survive a changing environment. At present, much emphasis is put upon molecular biological regulation. However, it is important that the metabolic processes that occur in the intact organism are still poorly defined. New technology allows the exploration of these processes, which should therefore prompt the initiation of further research in this area.

Increased whole-body protein and glutamine turnover in advanced cancer is not matched by an increased muscle protein and glutamine turnover

In the progress of cancer major disturbances in protein and glutamine metabolism have been observed. Muscle is the major protein pool and glutamine source in the body. The aim of this study was to investigate whether changes in whole-body protein and glutamine turnover, induced by cancer, are matched by similar changes in regional muscle metabolism. A MCA sarcoma was implanted subcutaneously in female Lewis rats. Rats were studied bearing small (5-15% of body weight) or large (15-30% of body weight) tumor loads and compared with sham-implanted free-fed and pair-fed controls. Body composition was determined by the distribution of an ip bolus of 3H2O. With the rat under anesthesia a primed constant infusion of L-[2,6-3H]phenylalanine and L-[3,4-3H]glutamine was given, and at steady state, whole-body, hindquarter-muscle, and tumor protein and glutamine turnover were calculated using compartment modeling. Anorexia was not observed in tumor-bearing rats. A small decrease in host carcass weight was observed in large-tumor-bearing rats by decreased fat mass. Whole-body protein turnover increased from 115 +/- 14 (nmole x 100 g body weight-1 x min-1) in free-fed controls rats to 239 +/- 29 in the large-tumor-bearing rats. Net tumor protein synthesis accounted for 28 +/- 1 and 49 +/- 1 nmole x 100 g body weight-1 x min-1. Muscle protein breakdown increased in the small-tumor-bearing group and decreased to control values in the large-tumor-bearing rats. Whole-body glutamine turnover remained unchanged in the small-tumor-bearing animals (2481 +/- 248 and 1996 +/- 268 nmole x 100 g body weight-1 x min-1 in control and small-tumor-bearing rats, respectively) and increased by 25% in the large-tumor-bearing animals. In contrast, muscle glutamine turnover more than doubled in the small-tumor-bearing group but returned to control values in the large-tumor-bearing animals. The current study show that in the presence of a small tumor whole-body protein turnover increased and that this was in part related to protein turnover of the tumor. Muscle protein breakdown increased in these rats with a concomitant increase in glutamine production from the hindquarter. In animals bearing larger tumors whole-body glutamine turnover increased. This increase, however, was only for a small part caused by tumor metabolism. Muscle glutamine turnover even decreased. Therefore, the increase in whole-body glutamine turnover appears to be caused by increased turnover in visceral organs.

Hepatic amino acid and protein metabolism in non-anorectic, moderately cachectic tumor-bearing rats

BACKGROUND/AIMS

Cancer cachexia is characterized by loss of lean body mass. Under this condition peripheral proteins are broken down and transferred to visceral organs and the tumor. The liver is the principal organ in the regulation of protein and amino acid metabolism, but liver amino acid kinetics in cancer are unclear. Therefore, we examined the effects of increasing tumor loads on hepatic protein turnover and amino acid handling.

METHODS

A MCA-induced sarcoma was implanted subcutaneously in Lewis rats (200-225 g). Rats were studied when the tumor was 5-15% or 15-30% of body weight. Control rats were sham implanted. Under anesthesia, a primed constant infusion of para-aminohippuric acid and L-[3, 4-3H]-valine was given to calculate hepatic substrate fluxes and protein turnover. Serum alpha 2-macroglobulin concentration was measured to determine the acute phase response.

RESULTS

Carcass weight decreased approximately 10% in large-tumor-bearing rats (p < 0.001). Liver wet weight increased from 5.5 +/- 0.1 (g) to 5.9 +/- 0.2 in the small-tumor-bearing group and 7.3 +/- 0.3 (p < 0.001) in the large-tumor-bearing group, with minimal changes in water content. Serum alpha 2-macroglobulin concentration, essential and gluconeogenic amino acid uptake by the liver increased in large-tumor-bearing animals. This contrasted with reduced liver ammonia uptake and unchanged urea production in tumor-bearing rats. In the small-tumor-bearing group liver protein synthesis increased, whereas protein breakdown remained unchanged. In the large-tumor-bearing group protein synthesis also increased, but protein breakdown decreased to zero.

CONCLUSIONS

The study shows that in tumor-bearing rats, liver uptake of essential and gluconeogenic amino acids increases without significant increases in urea or glucose production. Synthesis of both structural and export proteins, e.g. acute phase proteins, increases suggesting that the liver becomes a more efficient nitrogen-sparing and active protein-synthesizing organ during the growth of a malignant tumor.

Muscle protein and amino acid turnover in rats in vivo: effects of short-term and prolonged starvation

1. Protein loss in muscle can be caused by decreased protein synthesis, increased breakdown or both. In small animals the tracer incorporation technique is mostly used to measure protein synthesis, but for degradation measurements in vitro or ex vivo settings are required. In human and large animal studies the arteriovenous dilution technique is used because it enables the measurement of synthesis and breakdown rates simultaneously. The applicability in small animals has not yet been proven. We used a starvation model to compare both techniques. 2. A primed constant infusion of L-[2,6-(3H)]phenylalanine was given to male Lewis rats after 16, 40, 64 and 112 h starvation. Protein synthesis rates of the gastrocnemius muscle were measured by the incorporation technique and compared with hindquarter protein turnover calculated in a two- and three-compartment arteriovenous dilution model. 3. Whole-body phenylalanine rate of appearance decreased from 456 +/- 32 after 16 h to 334 +/- 34 (nmol min-1 100 g-1 body weight) after 112 h starvation. Protein synthesis rates of the gastrocnemius muscle measured by the tracer incorporation technique decreased from 3.6 +/- 0.4 after 16 h starvation to 2.2 +/- 0.3 after 64 h starvation and 1.8 +/- 0.4 (%/day) after 112 h starvation. Hindquarter protein breakdown, calculated with the tracer dilution model, increased after 112 h starvation from 28 +/- 12 to 77 +/- 15 nmol min-1 100 g-1 body weight. Using the tracer dilution model, however, the calculated protein synthesis rate across the hindquarter also increased after prolonged starvation (29 +/- 7 and 68 +/- 16 nmol min-1 100 g-1 body weight after 16 and 112 h respectively). In conjunction with this, calculated bidirectional membrane transport rates were also enhanced. Using valine and glutamine as tracers, the enhanced amino acid turnover rates were confirmed. 4. In conclusion, our results show that during short periods of starvation both methods give similar results. After prolonged starvation, however, an opposite change in disappearance rate and protein synthesis rate was observed. Assumptions made to calculate protein turnover using the arteriovenous dilution model may account for the discrepancy and care must be taken with the interpretation when using only one model in anaesthetized small animals.

In vivo amino acid metabolism of gut and liver during short and prolonged starvation

During starvation, splanchnic organs are proportionally more affected by protein loss than other organs. Amino acid membrane transport is one of the regulating mechanisms of protein turnover, but until now in vivo data were lacking. To study in vivo phenylalanine and tyrosine membrane transport and protein turnover in splanchnic organs, a primed continuous infusion of L-[2,6-3H]phenylalanine was given to control rats (postabsorptive) and after short (40 h) and prolonged (112 h) starvation. Data were analyzed using a three-compartment model previously used in muscle membrane transport studies. Inward and outward amino acid plasma-tissue membrane transport rates in both the liver and gut were upregulated after prolonged starvation. Metabolic shunting of phenylalanine and tyrosine increased in the gut but decreased to zero in the liver after prolonged starvation. In conjunction with this, gut and liver protein turnover increased after prolonged starvation. In the liver the net uptake of gluconeogenic precursors also increased, indicative for increased gluconeogenesis. The observed changes in amino acid metabolism in both splanchnic organs after prolonged starvation may reflect an adaptation of the gut and liver to nutritional deprivation and could be of benefit during refeeding.