Transvaginal posterior colporrhaphy combined with laparoscopic ventral mesh rectopexy for isolated Grade III rectocele: a prospective study of 27 patients

AIM

The aim of this study was to evaluate prospectively transvaginal posterior colporrhaphy (TPC) combined with laparoscopic ventral mesh rectopexy (LVR) in patients with a symptomatic isolated rectocele.

METHOD

Patients with these complaints underwent dynamic and static MRI. All consecutive patients with a Grade III (4 cm or more) rectocele and without internal/external rectal prolapse, enterocele and external sphincter damage were operated on. The patients completed the Obstructed Defecation Syndrome (ODS) score and the Cleveland Clinic Incontinence Score (CCIS). All tests were repeated after treatment. Dynamic disorders of the pelvic floor detected by MRI were recorded.

RESULTS

In 27 patients [median age 67 (46-73) years], TPC combined with LVR was feasible. Complications were limited to port site infection in two patients. Sexual discomfort (n = 8) due to prolapse diminished in six (75%) patients and in one (4%) de novo dyspareunia developed after treatment. The median follow-up was 12 (10-18) months. The median CCIS was 12 (10-16) before treatment and 8 (7-10) after (P < 0.0001). The median ODS score was 19 (17-23) before and 6 (3-10) after treatment (P < 0.0001). There was no change in urinary symptoms.

CONCLUSION

TPC combined with LVR for obstructed defaecation and faecal incontinence in patients with Grade III rectocele significantly relieves the symptoms of these disorders.

Perioperative nutritional support: a randomised clinical trial

Ever since methods of artificial nutritional support became available, attempts have been made using this form of treatment to reduce mortality and morbidity in surgical patients. Many trials have addressed this question, but very few have given a meaningful answer because of conceptual and methodological flaws. We therefore undertook a prospective randomised trial investigating the effects of at least 10 days pre-operative total parenteral nutrition (TPN) (n = 51) or total enteral nutrition (TEN) (n = 50) providing 150% basal energy expenditure (BEE) non-protein energy, to reduce major postoperative complications and mortality in a homogeneous patient group with signs of depletion. 50 patients served as a depleted control group (D) and 49 patients served as a non-depleted reference group (ND) and were operated upon without delay. Depleted control patients suffered significantly more septic complications than did patients in the non-depleted reference group (p < 0.05). There was no significant difference, however, in septic complications between either of the nutritional support groups and the non-depleted control group. In high risk patients, with weight loss >10% of body weight and over 500 ml blood loss during operation, a significant decrease in major complications was observed (p < 0.05) as a result of nutritional support. We conclude that pre-operative nutritional support, in patients with severe depletion, results in a reduction in major complications to a degree that justifies its routine use in this selected group of patients.

Have we enough glutamine and how does it work? A clinician's view

There is a gap between the scientific basis of the claim that in several disease states glutamine is lacking and the widespread belief that supplementation of glutamine to the nutritional regimen is beneficial in severely ill patients. Glutamine shortage exists when consuming tissues, playing a crucial role in the response to trauma and disease, receive insufficient amounts of glutamine. In these tissues (immune system, wound), glutamine is only partly oxidized but has more specific roles as nontoxic nitrogen carrier, precursor of several crucial metabolites required for cell proliferation and for maintenance of the redox potential, and as osmolyte. In inflammatory states, glutamine concentrations in plasma and tissues are decreased due to many disease-related factors, precluding its use as a reliable indicator of shortage. Isotope studies have yielded equivocal results, precluding their use as a reliable indicator of glutamine shortage or adequacy. The increase in the net release of glutamine from peripheral tissues to central tissues (immune system, liver, spleen, wound) in inflammatory states provides a better basis for the necessity to supplement the organism with extra glutamine in these conditions. Glutamine supplementation was beneficial in a few studies in burn or trauma patients. The clinical benefit of parenteral glutamine supplementation in patients with severe inflammation has been demonstrated more convincingly. The amounts of glutamine supplemented approximate the amounts released by peripheral tissues and utilized by central organs operative in host defense and are therefore in the physiological range.

Autologous platelet-derived growth factors (platelet-rich plasma) as an adjunct to mucosal advancement flap in high cryptoglandular perianal fistulae: a pilot study

AIM

The aim of this study was to explore autologous platelet-rich plasma as an adjunct to the staged mucosal advancement flap in the treatment of perianal fistulae.

METHOD

Between February 2006 and May 2007, 10 patients with fistula tracts transversing from the middle-third or upper part of the anal sphincter were treated for at least 3 months with noncutting setons prior to definitive closure by autologous platelet-rich plasma as an adjunct to a mucosal advancement flap. Five patients smoked tobacco.

RESULTS

The study group consisted of six women and four men with a median age of 44 (range 30-75) years and a median follow up of 26 (range 17-32) months. One (10%) patient had a recurrent fistula. No new continence disorders developed after definitive treatment in both groups.

CONCLUSION

Platelet-rich plasma as an adjunct to a staged mucosal advancement flap for the treatment of perianal cryptoglandular fistulae is a promising treatment modality and seems to establish a high healing rate.

Health-related quality of life in patients treated for enterocutaneous fistula

BACKGROUND

Patients with enterocutaneous fistulas undergo long intensive treatment. The aim of this study was to investigate the long-term health-related quality of life (HRQL) of these patients.

METHODS

Consecutive patients treated for enterocutaneous fistula between 1990 and 2005 were eligible for this retrospective study. The Karnofsky Performance Scale (KPS), Short Form 36 (SF-36) and the Inflammatory Bowel Disease Questionnaire were used to measure HRQL. The SF-36 was matched with results from healthy controls. Patients also gave information on concurrent medical illnesses.

RESULTS

Of 135 patients, 44 died, 14 were lost to follow-up and 12 refused to participate; of the remaining 65, 62 participated (response rate 81 per cent). HRQL was independent of patient characteristics during treatment. Scores for SF-36 domains were lower than in their matched controls (P < 0.050). Concurrent medical illness (cancer, depression and gastrointestinal disease) significantly reduced HRQL (for example with a 40 per cent reduction in vitality). The median KPS score was 80, indicating that activities could be performed with effort and patients had some signs of disease.

CONCLUSION

HRQL is lower in patients treated for enterocutaneous fistula than in matched controls, particularly in those with concurrent medical illnesses. Patients treated successfully have normal independence in daily functioning.

The value of objective measurements to select patients who are malnourished

Several studies have attempted to define nutritional parameters that can be used to select malnourished hospitalised patients for nutritional support. A combination of objective nutritional parameters was evaluated in a group of 50 patients selected for total parenteral nutrition on clinical grounds only and compared with a control group. This control group consisted of 38 patients who were admitted for elective minor surgical procedures such as varicectomy and hernia repair. On a subset of 18 objective nutritional measurements, discriminant analysis was performed. In the evaluation it was shown that a combination of albumin (ALB), prealbumin (PALB), total lymphocyte count (TLC) and the percentage of ideal weight (PIW) was the most useful combination of nutritional tests in discriminating a chosen malnourished (M) group and a control group who were declared not malnourished (NM). With this combination the patients were correctly classified in 93% with a sensitivity of 93% and a specificity of 94%.

Long-term outcome following mucosal advancement flap for high perianal fistulas and fistulotomy for low perianal fistulas: recurrent perianal fistulas: failure of treatment or recurrent patient disease?

BACKGROUND

In this study, we determined the long-term outcome of perianal fistulas treated with mucosal advancement flap (MF) or fistulotomy (FT).

METHODS

One hundred three patients with perianal fistulas were treated by MF for high fistulas or FT for low fistulas and were retrospectively assessed by case-note review and examined at the out-patient clinic. The localization and time of recurrence of the fistula were recorded.

RESULTS

Forty-one patients [median follow-up of 72 months (range 48-99)] were treated by an MF, and 62 patients [median follow up of 75 months (range 48-99)] were treated by FT. After 12, 48, and 72 months, the fistula had recurred in 9 (22%), 26 (63%), and 26 (63%) patients of the MF group and in 4 (7%), 16 (26%), and 24 (39%) patients of the FT group, respectively. Eighteen (69%) of the recurrences in the MF group and ten (33%) of the FT group occurred within 24 months after surgery (p=0.01). Four (15%) of the recurrences in the MF group and 13 (54%) of the recurrences in the FT group were present in a different localization (p=0.007).

CONCLUSION

The success rate of both FT and MF techniques decreases with time. Recurrence appears to be caused by failure of treatment and by recurrent patient disease.

Application of subjective global assessment as a screening tool for malnutrition in surgical patients in Vietnam

BACKGROUND AND AIMS

In most hospitals in Vietnam, clinical assessment of nutritional status has yet to become part of the routine clinical history taking and physical examination. It is the aim of this study to apply subjective global assessment (SGA) of nutritional status in surgical patients in the Mekong Delta, Vietnam, to determine the incidence of malnutrition according to SGA and to know whether there was an association between SGA class and infectious complications.

METHODS

A prospective, cross-sectional study design was used. SGA of nutritional status was applied. Patients were rated as well nourished (A), moderately malnourished (B) or severely malnourished (C). Infectious complications (wound infection, intra-abdominal abscesses, anastomotic leakage) were recorded.

RESULTS

Of the 438 patients assessed, 194 (44.3%) were classified as A, 126 patients (28.8%) were classified as B and 118 patients (26.9%) were classified as C. Of the 274 patients who underwent major abdominal surgery assessed, 61 patients (22.3%) were classified as A, 97 patients (35.4%) were classified as B and 116 patients (42.3%) were classified as C. Weight loss and percent weight loss, muscle wasting, loss of subcutaneous fat, functional capacity and significant gastrointestinal symptoms correlate significantly with the severity of SGA class (P<0.001). The rate of postoperative infectious complications was higher in patients classified as SGA class C (33.6%) than as class A (6%) and B (11%).

CONCLUSIONS

A high rate of malnutrition was found, applying SGA of nutritional state in surgical patients in Vietnam. Malnutrition was associated with an increase in infectious complications. Special attention should be paid to weight loss, muscle wasting, loss of subcutaneous fat, functional capacity and gastrointestinal symptoms.

Laparoscopic adjustable gastric banding versus open vertical banded gastroplasty: a prospective randomized trial

BACKGROUND

Laparoscopic adjustable gastric banding (LAGB) and open vertical banded gastroplasty (VBG) are treatment modalities for morbid obesity. However, few prospective randomized clinical trials (RCT) have been performed to compare both operations.

METHODS

100 patients (50 per group) were included in the study. Postoperative outcomes included hospital length of stay (LOS), complications, percent excess weight loss (%EWL), BMI and reduction in total comorbidities. Follow-up in all patients was 2 years.

RESULTS

LOS was significantly shorter in the LAGB group. 3 LAGB were converted to open (1 to gastric bypass). Directly after VBG, 3 patients needed relaparotomies due to leakage, of which one (2%) died. After 2 years, 100% follow-up was achieved. BMI and %EWL were significantly decreased in both groups but significantly more in the VBG group compared to the LAGB group (31.0 kg/m2 and 70.1% vs 34.6 and 54.9% respectively). Co-morbidities significantly decreased in both groups in time. 2 years after LAGB, 20 patients needed reoperation for pouch dilation/slippage (n=12), band leakage (n=2), band erosion (n=2) and access-port problems (n=4). In the VBG group, 18 patients needed revisional surgery due to staple-line disruption (n=15), narrow outlet (n=2) or insufficient weight loss (n=1). Furthermore, 8 VBG patients developed an incisional hernia.

CONCLUSION

This RCT demonstrates that, despite the initial better weight loss in the VBG group, based on complication rates and clinical outcome, LAGB is preferred. It had a shorter LOS and less postoperative morbidity.

Staged mucosal advancement flap for the treatment of complex anal fistulas: pretreatment with noncutting Setons and in case of recurrent multiple abscesses a diverting stoma

OBJECTIVE

To assess the efficacy of a staged strategy for the treatment of complex perianal fistula.

METHODS

Between January 1999 and April 2003 all consecutive patients with complex perianal fistulas were treated according to a staged strategy. Fistula tracks originating from the middle third or upper part of the anal sphincter were included. Patients were examined for recurrent fistulas and complaints of incontinence and soiling. Initial treatment consisted of a noncutting seton with or without a diverting stoma. Definitive surgical treatment consisted of an advancement flap or fistulotomy.

RESULTS

Thirty patients were included (median age; 42 years, range 22-68 years). Seven had Crohn's disease without signs of rectal and anal involvement other than the fistula. At a median follow up of 22 months (range 8-52 months) in 29 (97%) patients, the wounds had healed completely; 7 (22%) patients subsequently developed a recurrent fistula and minor soiling occurred in 7 (23%) patients.

CONCLUSION

Initial treatment with a seton with and without a diverting stoma minimizing inflammatory activity at the fistula site before definitive surgical treatment gave good results in this difficult group of patients.

Effects of long-term intravenous and intragastric L-arginine intervention on jejunal motility and visceral nitric oxide production in the hyperdynamic compensated endotoxaemic pig

Alterations in L-arginine availability and nitric oxide (NO) synthesis in the intestinal muscularis may contribute to disturbed small intestinal motility that is observed during endotoxaemia. The aim of this study was to evaluate the effect of L-arginine infusion on visceral NO production and jejunal motility in hyperdynamic compensated endotoxaemic pigs. Fasted and saline-resuscitated pigs were intravenously infused for 24 h with endotoxin (lipopolysaccharide, 50 ng kg(-1) min(-1)) or saline (n = 6). Endotoxaemic pigs received either intravenous L-arginine (n = 6, 5.3 micromol kg(-1) min(-1)) or L-alanine (isocaloric, n = 6). After 24 h, intravenous L-arginine or L-alanine infusion was continued intragastrically for 32-h in an enteral meal. During (0-24 h) and 1 day postendotoxaemia (48-56 h), jejunal motility was recorded by manometry and analysed for migrating motor complex (MMC) characteristics. Visceral NO production was measured at 24 and 48 h by 15N2-arginine-to-15N-citrulline conversion. Visceral NO production was increased during endotoxaemia and was higher in L-arginine than in L-alanine-treated pigs. One day postendotoxaemia, visceral NO synthesis was still increased in L-arginine but not in L-alanine-treated animals. Endotoxaemia shortened the MMC cycle duration and accelerated the MMC propagation velocity. Both were restored by L-arginine. Similar motility disturbances were observed one day postendotoxaemia and were also compensated by L-arginine infusion.

Case study of the clinical usefulness of bioelectrical impedance spectroscopy in evaluating nutritional status

Bioelectrical impedance spectroscopy (BIS) can be a valuable tool in assessing changes in body composition. Although the validity of BIS in healthy subjects is relatively good, in patients considerably larger measurement errors have been reported. In this article the clinical usefulness of BIS in assessing nutritional status of one case study will be discussed. Interpretation of the predictions of BIS in this unstable patient was difficult. This is in agreement with the consensus that BIS does not give accurate prediction of body composition in individual patients. It is recommended that validation studies of BIS should focus on clinical aspects which can influence BIS measurements.

Bio-electrical impedance spectroscopy: alternatives for the conventional hand-to-foot measurements

BACKGROUND AND AIMS

Bio-impedance spectroscopy (BIS) is a very attractive method for measuring body composition. The standard method measures impedance from hand to foot. However, in patients a hand or foot is not always accessible. In these cases alternative methods would be helpful. The objective of this study was to compare BIS measurements from hand to foot (HF) with foot to foot (FF) and hand to hand (HH) measurements as alternatives. Aims were firstly, to assess the relationship between resistance (R) values measured by the different methods, secondly, to study the influence of body geometry on this relationship and lastly, to assess the predictive capacity of the methods for measuring body fluid volumes.

METHODS

In 53 subjects with different degrees of obesity (mean BMI = 38; SD = 9 kg/m(2)) three BIS measurements were performed from HF, HH and FF with a Xitron 4000B machine. Resistances of extracellular (Recw) and intracellular water (Ricw) were extrapolated by fitting the data to a Cole-Cole plot. Total body water (TBW) and extracellular water (ECW) were measured by deuterium and bromide dilution respectively. Intracellular water (ICW) was calculated as TBW-ECW. Anthropometric measurements, including length and circumference of limbs and trunk, were performed as measures for body geometry.

RESULTS

The Recw, Ricw and R50 values of HF measurements could be accurately described as a function of the Recw, Ricw and R50 values of HH or FF measurements. The relative circumference of arms and legs and the length of the trunk influenced the relationship between R values of the three different measurements. The degree of overweight did not affect this relationship. The precision of the predictions of TBW, ECW and ICW based on R values of the HH measurements were comparable with the traditional HF measurements while the FF measurements gave slightly less accurate results.

CONCLUSIONS

Under circumstances where total body BIS measurements cannot be performed, FF or HH measurements may be used as alternatives. However, for clinical use the effect of changes in fluid distribution on the accuracy of these methods needs to be studied further.

Differential effects of selective and non-selective NOS inhibition on renal arginine and protein metabolism during endotoxemia in rats

BACKGROUND AND AIMS

The kidney is the main endogenous producer of circulating arginine. Renal arginine disposal is directed to protein synthesis, urea production and nitric oxide synthesis. The administration of nitric oxide synthase inhibitors during sepsis may be beneficial or detrimental depending on the specificity of the inhibitor. We aimed to measure the effects of two NOS inhibitors, with different specificity, on renal arginine and protein turnover in a rat model of sepsis.

METHODS

Rats were subject to double hit endotoxemia and either L-NAME (non-specific), SMT (iNOS specific) or saline. Under anesthesia, vessels supplying and draining the kidney were catheterized. Systemic and intra-renal arginine and protein metabolism were measured using a primed continuous infusion of L-[2,3-(3)H]arginine and L-[2,6-(3)H]phenylalanine.

RESULTS

Non-specific NOS reduced systemic protein and arginine turnover, whereas selective iNOS inhibition did not. In the kidney, blood flow was reduced by L-NAME, but not by SMT. In conjunction with this, non-selective NOS inhibition increased renal protein breakdown, whereas selective iNOS inhibition increased renal arginine production.

CONCLUSIONS

This study shows that non-selective NOS inhibition using L-NAME is detrimental for systemic and renal protein metabolism. Selective NOS inhibition stimulates renal arginine synthesis, without changing circulating arginine levels.

Decreased plasma orexin-A levels in obese individuals

Orexin-A and -B stimulate appetite and food intake in rats. Orexins and orexin receptors are present in the hypothalamus as well as the enteric nervous system, the pancreas and the gut. The presence of orexins in peripheral blood, however, has not yet been reported. To determine whether orexin-A is present in human plasma and is related to body weight, we measured plasma orexin-A and leptin levels in a population with a body mass index (BMI) range from 19.8 to 59 kg/m(2). Plasma orexin-A levels correlated negatively and plasma leptin levels correlated positively with BMI. In obese and morbidly obese individuals, orexin-A levels were significantly lower and leptin levels were significantly higher when compared to normal. Our results support previous data suggesting that orexin-A acts also in a peripheral manner. The fact that lower levels of plasma orexin-A are present in obese individuals suggests that it is involved in the regulation of human energy metabolism.

The effect of glutamate infusion on cardiac performance is independent of changes in metabolism in patients undergoing routine coronary artery bypass surgery

In a double-blind randomized placebo-controlled study, the effects of intravenous glutamate infusion on myocardial haemodynamics and metabolism were studied in 22 patients undergoing routine coronary artery bypass graft (CABG) surgery. Immediately after aortic cross-clamp release, an intravenous infusion of a solution of glutamate (125 mmol x l(-1)) at a rate of 1.5 ml x h(-1) x kg(-1) was given over 1 h to 11 patients (G group). The other 11 patients received a placebo infusion (0.9% NaCl) (P group). Haemodynamic functions and rates of exchange of glucose, non-esterified fatty acids and lactic acid over the heart were measured before sternotomy (T1), 40 min after cross-clamp release (T2) and 4 h after cross-clamp release (T3). At T2, decreases were seen in comparison with T1 in systemic vascular resistance index, and increases were seen in cardiac index and coronary sinus flow. All of these changes were greater in the G group than in the P group (P<0.05). Myocardial glutamate consumption increased 2-fold after glutamate administration. No significant changes were observed in the myocardial utilization of glucose, lactate or non-esterified fatty acids between the P and the G groups at T1, T2 or T3. These data show that an intravenous glutamate infusion after routine CABG surgery significantly improved cardiac haemodynamic performance without direct effects on cardiac substrate metabolism. This suggests that a reduction of the afterload via a peripheral vasodilatory effect is the main mechanism leading to the observed changes in haemodynamics. Earlier claims that patients with post-operative cardiac failure show metabolic benefits from the glutamate infusion do not seem to apply to patients undergoing routine CABG surgery.

Increased leptin concentrations correlate with increased concentrations of inflammatory markers in morbidly obese individuals

OBJECTIVE

To study whether an increase of plasma leptin concentrations, as observed in the case of increased body weight, is associated with an inflammatory state.

SUBJECTS

Sixty-three healthy subjects with body mass index (BMI) ranging from 20 to 61 kg/m2.

MEASUREMENTS

Plasma concentrations of leptin, the inflammatory parameter soluble TNF-alpha receptors (TNFR55 and TNFR75), the acute phase proteins lipopolysaccharide binding protein (LBP), serum amyloid A (SAA), alpha-acid glycoprotein (AGP), C-reactive protein (CRP), plasminogen activator inhibitor-1 (PAI-1) and the anti-inflammatory soluble Interleukin-1 decoy receptor (sIL-1RII) were measured.

RESULTS

As expected, BMI correlated significantly with leptin (r=0.823, P<0.001), but also with all acute phase proteins, both soluble TNF receptors and PAI concentrations. After correction for BMI and sex, no significant correlation between leptin and the acute phase proteins was seen. Interestingly, however, leptin strongly correlated with both TNF receptors (r=0.523, P<0.001 for TNFR55 and r=0.438, P<0.001 for TNFR75).

CONCLUSIONS

This study shows the development of a pro-inflammatory state with increasing body weight. The BMI independent relationship between leptin and both soluble TNF-receptors is consistent with a regulatory role for leptin in the inflammatory state in morbidly obese subjects.

Gastrointestinal actinomycosis: an unusual presentation with obstructive uropathy: report of a case and review of the literature

A 55-year-old female patient is described who had recurrent retroperitoneal infections without an apparent focus. After a protracted period of illness the infection proved to be caused by actinomycosis. An unusual feature of the inflammatory process consisted of obstruction of the ureters, ultimately resulting in destruction of the left kidney. Hydronephrosis resulting from inflammatory fibrosis has not been reported in the literature before.

Role of bioimpedance spectroscopy in assessment of body water compartments in hemodialysis patients

Bioimpedance spectroscopy (BIS) has been advocated as a tool to assess fluid status in hemodialysis (HD) patients. However, uncertainty remains about the reliability of BIS in patients with abnormalities in fluid status. Aims of the study are to assess the agreement between total-body water (TBW) and extracellular volume (ECW) measured by BIS and tracer dilution (deuterium oxide [D(2)O] and sodium bromide [NaBr]), the influence of the relative magnitude of water compartments (expressed as TBW(D(2)O) and ECW(NaBr):body weight) on the agreement between BIS and tracer dilution, and the ability of BIS to predict acute changes in fluid status. BIS and tracer dilution techniques were performed in 17 HD patients before a dialysis session. Moreover, the relation between BIS and gravimetric weight changes was assessed during both isolated ultrafiltration and HD. Correlation coefficients between TBW and ECW measured by BIS and tracer dilution were r = 0.71 and r = 0.71, respectively. Mean differences (tracer-BIS) were 6.9 L (limits of agreement, -1.5 to 21.6 L) for TBW and 2.3 L (limits of agreement, -1.7 to 9.7 L) for ECW. There was a significant relationship between the relative magnitude of TBW and ECW compartments and disagreement between BIS and tracer dilution (r = 0.65 and r = 0.77; P < 0.05). During both isolated ultrafiltration and HD, there was a significant relation between gravimetric changes and change in ECW(BIS) (r = 0.83 and r = 0.76; P < 0.05), but not with change in TBW(BIS). In conclusion, agreement between BIS and tracer dilution techniques in the assessment of TBW and ECW in HD patients is unsatisfactory. The discrepancy between BIS and dilution techniques is related to the relative magnitude of body water compartments. Nevertheless, BIS adequately predicted acute changes in ECW during isolated ultrafiltration and HD, in contrast to changes in TBW.

Nutrition in patients with acute pancreatitis

Acute pancreatitis is a disease with varying severity. Patients with the mild form do not require nutritional support because oral intake is resumed rapidly. Studies on nutritional support in acute pancreatitis have included patients with both mild and severe disease. In this heterogeneous group, total parenteral nutrition did not improve outcome compared with no nutrition at all. This is caused in part by an increase in septic complications during total parenteral nutrition. Likewise, no benefit from enteral nutrition was observed compared with no nutrition, probably because the group was heterogeneous or because nutritional goals were not achieved. Patients with severe acute pancreatitis become profoundly catabolic. This group undoubtedly requires nutritional support to treat undernutrition. The limited available data indicate that enteral nutrition, if well tolerated, is superior to parenteral nutrition for patients with severe acute pancreatitis. Based on current knowledge, a combination of early total parenteral nutrition and enteral nutrition is advisable as soon as enteral nutrition is tolerated. Monitoring of gut function is crucial in this situation.

Endotoxemia affects organ protein metabolism differently during prolonged feeding in pigs

The metabolic response after sepsis is characterized by net protein loss. Nutritional intervention often is applied to sustain whole body protein mass under such circumstances. The manner in which protein metabolism of the different organs is affected under nutrition-supported and postseptic circumstances remains ambiguous. Therefore, we explored the changes in in vivo organ and whole body protein turnover after endotoxin-induced sepsis during enteral nutrition in pigs. The use of isotopes enabled simultaneous measurements of protein synthesis, breakdown and amino acid degradation across the portal-drained viscera (PDV; approximately intestine), liver and hindquarter ( approximately 50% skeletal muscle). All pigs received a continuous enteral infusion of a liquid meal equivalent to 0.3 g protein. kg bw(-1). h(-1) 3 d before and 4 d after a 24-h endotoxemia period. Measurements were performed 1 d before and 1 and 4 d after endotoxemia that was induced by a 24-h endotoxin (3 microg. kg bw(-1). h(-1) lipopolysaccharide, n = 7) infusion. Controls received NaCl (n = 7). At 4 d after endotoxemia, hindquarter protein turnover was increased, resulting in net synthesis. The amino acid output by the PDV was increased 1 and 4 d after endotoxemia. In the liver, net protein synthesis was enhanced 1 d after endotoxemia. Increased amino acid transamination in hindquarter and PDV led to glutamine and alanine effluxes that serve as substrates for liver and, possibly, the immune system. By providing substrate, enteral nutrition can sustain elevated amino acid demand in the postendotoxemic state by hindquarter, PDV and liver for protein synthesis and transamination processes.

Response of glutamine metabolism to glutamine-supplemented parenteral nutrition

BACKGROUND

Increasing evidence suggests that glutamine is important for the function of many organ systems and supports the use of glutamine-enriched total parenteral nutrition (TPN) during severe illness. However, the effect of prolonged glutamine supplementation on glutamine kinetics has not been studied.

OBJECTIVE

We investigated the effect of 8-10 d of TPN enriched with glutamine dipeptides on glutamine kinetics.

DESIGN

Twenty-three preoperative patients were randomly allocated to receive either TPN enriched with glutamine dipeptides (60 micromol glutamine*kg body wt(-1)*h(-1)) or isonitrogenous, isoenergetic, glutamine-free TPN. A primed, continuous, 6-h intravenous infusion of L-[5-(15)N]glutamine and L-[1-(13)C]leucine was given before (baseline) and 8-10 d after the TPN solutions were administered. Baseline measurements were performed after a 40-h administration of a standard solution of glucose and amino acids (no glutamine).

RESULTS

Glutamine-enriched TPN increased the total appearance rate of glutamine (P: < 0.05) but did not inhibit or increase the endogenous appearance rate. The standard TPN solution also increased the glutamine appearance rate (P: < 0.05), but the change was much smaller than in the glutamine-supplemented group (P: < 0.01). The plasma glutamine concentration did not rise significantly during either treatment, suggesting increased tissue glutamine utilization, especially in the glutamine-supplemented group.

CONCLUSION

In view of the enhanced glutamine requirements in response to trauma and disease by tissues such as those of the gut, the immune system, and the liver, increased glutamine availability during glutamine-enriched TPN may be beneficial preoperatively in patients with gastrointestinal disease.

Renal amino acid metabolism during endotoxemia in the rat

BACKGROUND

The kidney has an important function in the exchange of nitrogenous metabolites. Glutamine is the most important substrate for renal ammoniagenesis and thus plays a crucial role in acid-base homeostasis. Furthermore, the kidney is the main endogenous source for de novo arginine production from citrulline, which in turn is derived from intestinal glutamine metabolism. Sepsis is a condition in which glutamine availability is reduced, whereas the need for arginine biosynthesis may be increased. Limited bioavailability of glutamine may affect arginine synthesis, which may have consequences for nitric oxide (NO) synthesis. Therefore, we studied renal glutamine and arginine metabolism in a rat model of endotoxemia and related this to NO metabolism.

MATERIALS AND METHODS

Rats were subject to double hit endotoxemia, and control rats received 0.9% NaCl. Renal blood flow was measured using para-aminohippuric acid. Concentrations of plasma amino acids and nitrate were measured in the aorta and renal vein to calculate net renal uptake or release of amino acids and address NO production.

RESULTS

The arterial concentrations of glutamine and ammonia were not changed in endotoxemic rats. Although renal glutamine uptake was reduced, total renal ammonia production was not changed during endotoxemia. The arterial concentration of citrulline and renal citrulline uptake was not altered in endotoxin-treated rats, but renal arginine production was increased. However, no effect was observed on nitric oxide production.

CONCLUSIONS

Although the kidney has very important functions in the excretion of waste products and in interorgan metabolism, this study suggests that the kidney has a limited role in glutamine, arginine, and NO metabolism during late endotoxemia in rats.

Energy, substrate and protein metabolism in morbid obesity before, during and after massive weight loss

OBJECTIVE

To investigate the effect of surgically induced weight loss on energy, substrate and protein metabolism of morbidly obese patients.

DESIGN

A prospective, clinical intervention study of morbidly obese patients before and after surgical treatment.

SUBJECTS

Eight morbidly obese patients (BMI 47.88+/-7.03).

METHODS

Total energy expenditure (TEE; doubly labeled water method), sleeping metabolic rate (SMR; respiration chamber), body composition (deuterium oxide component of doubly labeled water), substrate metabolism (48 h dietary records, 48 h urine collection and gaseous exchange in the respiration chamber) and whole body protein turnover (primed-continuous infusion of L-[1-13C]-leucine) were measured before, 3 and 12 months after vertical banded gastroplasty (VBG).

RESULTS

The TEE decreased as a result of a decreased SMR (64%) and non-SMR (36%; P=0.001). SMR as a function of fat-free mass (FFM) decreased after weight loss (P<0.05). The physical activity index (PAI), defined as TEE/SMR, was low and was not influenced by weight loss. Protein and carbohydrate oxidation decreased significantly after VBG (P<0.05), although 3 months after VBG protein oxidation did not decrease enough to prevent loss of FFM. The energy used for protein turnover was approximately 24% of SMR and did not change after weight loss.

CONCLUSIONS

Compensatory processes that oppose weight loss of morbidly obese patients exist, as demonstrated by the disproportional reduction of SMR, and a low PAI. Protein turnover is not a major contributor to the disproportional reduction of SMR.

Glutamine appearance rate in plasma is not increased after gastrointestinal surgery in humans

The metabolic response to surgical stress is characterized by muscle protein breakdown and mobilization of amino acids and has been postulated to furnish glutamine and other amino acids to the immune system, gut and liver. The present study was undertaken to investigate whether the whole body appearance rate (R(a))(3) of glutamine in plasma is increased after major elective surgery. Fourteen patients (8 males, 6 females) were measured prior to laparotomy and on the second postoperative day. Patients received a primed continuous 6-h infusion of L-[5-(15) N]glutamine and L-[1-(13)C]leucine, and arterial blood samples and muscle biopsies were taken for concentration and enrichment measurements. As expected, the metabolic response to surgery was characterized by a rise in whole body protein breakdown (n = 14, P < 0.001) and a decreased concentration of glutamine in plasma (n = 14, P < 0.001) and muscle (n = 8, P < 0.01). However, these catabolic changes were not reflected by an increase in the plasma R(a) of glutamine: 246 +/- 8 micromol. kg(-1). h(-1) before surgery vs. 241 +/- 10 micromol. kg(-1). h(-1) on the second postoperative day. We conclude that the whole body R(a) of glutamine in plasma is not increased 2 d after elective gastrointestinal surgery. Further studies are warranted to establish whether the lack of an increase in plasma glutamine R(a) provides a rationale for glutamine supplementation.

Tracer methodology in whole body and organ balance metabolic studies: plasma sampling is required. A study in post-absorptive rats using isotopically labeled arginine, phenylalanine, valine and leucine

BACKGROUND AND AIMS

Radioactive and stable amino acid isotopes are frequently used in metabolic research. Blood cells contain amino acid transporters, which may influence tracer distribution in blood. The aim of this study was to determine whether plasma or whole blood specific activity or enrichment of amino acid tracers should be used in the calculation of whole body and organ production rates.

METHODS

Seven male Wistar rats were infused with L-[2,3-(3)H]-Arginine, L-[2, 6-(3)H]-Phenylalanine, L-[3,4-(3)H]-Valine, and [L-[4,5-(3)H]-Leucine. Whole body and portal drained visceral, hepatic and renal production rates of arginine, phenylalanine, valine and leucine were determined in plasma and in whole blood.

RESULTS

Amino acid tracers that equilibrate well between plasma and blood cells (for instance phenylalanine, valine and leucine) yield similar whole body production rates when whole blood or plasma is sampled. Also, organ production rates measured using these amino acid tracers are consistent. However, a discrepancy exists between the whole body production rate and the sum of PDV, hepatic and renal production rates. When tracers are used that do not equilibrate well between plasma and blood cells (for instance arginine) the use of whole blood specific activity in the calculations yield overestimations of whole body and organ production rates.

CONCLUSION

From our data we recommend plasma sampling and strongly advise against whole blood sampling in metabolic organ balance studies in which amino acid tracers are used.

Validation of bio-impedance spectroscopy: effects of degree of obesity and ways of calculating volumes from measured resistance values

BACKGROUND

Bioelectrical-impedance spectroscopy (BIS) is a very attractive method for body composition measurements in a clinical setting. However, validation studies often yield different results. This can partly be explained by the different approaches used to transform measured resistance values into body compartments.

OBJECTIVE

The aim of this study was to compare the linear regression (LR) method with the Hanai Mixture theory (HM). Secondly, the effect of degree of overweight on the accuracy of BIS was analysed.

DESIGN

In 90 people (10 M, 80 F; body mass index (BMI) 23-62 kg/m2) total body water (TBW) and extracellular water (ECW) were measured by deuterium and NaBr dilution methods, respectively, and by BIS. Resistance values of ECW (R(ECW)) and TBW (R(TBW)) were used for volume calculations. Data of half the group were used for LR based on L2/R (L = length, R = resistance) to predict TBW and ECW and to calculate the constants used in the HM (kECW), k(p)). Prediction equations and constants were cross-validated in Group 2.

RESULTS

Bland and Altman analysis showed that the LR method underestimated TBW by 1.1 l (P < 0.005) and ECW by 1.1 l (P < 0.005). The HM approach underestimated ECW by 0.8 l (P < 0.005). The correlations with the dilution methods and the SEEs for TBW and ECW were comparable for the two approaches. The prediction error of BIS for TBW and ECW correlated with BMI. The constant kECW, and the specific resistivities of the ECW and intracellular water (ICW) pECW and pICW were also correlated with BMI.

CONCLUSIONS

The mixture approach is slightly more accurate than linear regression, but not sensitive enough for clinical use. The constants used in the HM model are not constants in a population with a wide variation in degree of overweight. The physical causes of the correlation between BMI and constants used in the model should be studied further in order to optimize the mixture model.

Increased lactulose/rhamnose ratio during fluid load is caused by increased urinary lactulose excretion

Noninvasive assessment of intestinal permeability in vivo is based on the measurement of urinary excretion of orally administered sugar probes. It is expressed as a ratio, usually lactulose/rhamnose or 3-O-methyl-D-glucose (3-OMG)/rhamnose. In both endotoxemic and control rats that were receiving fluid, we observed an increase in the recovery of lactulose and 3-OMG but not rhamnose in both groups, suggesting an enhancement of intestinal permeability. In the measurement of intestinal permeability, all pre- and postmucosal factors are considered equal for all sugars. We hypothesized that postmucosal factors and not changes in intestinal permeability caused the increased urinary lactulose and 3-OMG recoveries observed during fluid loading. Therefore, the effects of fluid loading on urinary excretion of the sugar probes were studied in healthy rats receiving the sugars intravenously. After intravenous injection, fluid loading increased urinary lactulose recovery threefold but not that of 3-OMG and rhamnose. In conclusion, fluid loading increases the lactulose/rhamnose ratio independent of changes in intestinal permeability. The 3-OMG/rhamnose ratio is not influenced by fluid loading.

A prospective cost-effectiveness analysis of vertical banded gastroplasty for the treatment of morbid obesity

BACKGROUND

Surgical treatment of morbid obesity is gaining in popularity, because conservative treatment is ineffective. However, a cost-effectiveness analysis has never been performed and is the main goal of the present study.

METHODS

21 consecutive morbidly obese patients were tested before and after vertical banded gastroplasty (VBG). Quality of life was assessed with the Nottingham Health Profile and a visual analogue scale. A prevalence-based cost-of-illness analysis of morbid obesity was performed and the cost-effectiveness of VBG assessed.

RESULTS

VBG resulted in a significant weight loss and an improved quality of life. The improved quality of life combined with 3.6 life-years gained after VBG resulted in 12 quality adjusted life-years (QALY) gained in a lifelong scenario. Lifelong costs of illness of morbidly obese persons ranged from $8,304 to $9,367. Total direct costs of VBG were $5,865. The percentage of patients performing paid labor increased from 19% before VBG to 48% after VBG, resulting in an average productivity gain of $2,765 per year. In summary, the cost-effectiveness analysis revealed that surgical treatment of morbid obesity by means of VBG saves $4,004 to $3,928 per QALY (overall dominance).

CONCLUSION

Because treatment of morbid obesity with VBG results in QALYs gained and less costs, there is no doubt that this procedure should be introduced or continued from a societal point of view.

[Glutamine as a key ingredient in protein metabolism]

Glutamine has a number of unique properties which suggest that this amino acid plays an important role in health and disease. Glutamine is considered a conditionally essential amino acid, because during periods of severe metabolic stress the body's requirements of glutamine may exceed the individual's ability to produce sufficient amounts of the amino acid. Studies with glutamine-enriched nutrition show beneficial effects on nitrogen balance, muscle protein metabolism, gastrointestinal mucosa, and immune status. In certain patient categories addition of glutamine reduces the number of infectious complications, improves long-term survival, and shortens hospital stay, e.g. bone marrow transplantation patients, neonates with severely subnormal weight, patients with multiple organ failure, multi-trauma patients. More studies are needed to document the dose-response and to identify the patients that are likely to benefit from glutamine supplementation.

Enhanced renal vein ammonia efflux after a protein meal in the pig

BACKGROUND/AIMS

The intake of dietary protein has been associated with increased arterial ammonia levels. However, the origin of this rise in ammonia levels is unknown. This study was designed to examine whether this increase is caused by ammonia formed by the gut escaping hepatic clearance, or ammonia formed by the kidney and subsequently released into the circulation.

METHODS

Splanchnic and renal fluxes of ammonia and amino acids were studied in 10 pigs that were fed in a randomized cross-over design with a protein meal (n = 8), a meal with an equimolar amount of free amino acids (n = 8) or an iso-osmolar NaCl solution (n = 6).

RESULTS

After the protein meal, and less pronounced after the amino acid meal, arterial ammonia levels increased from approximately 25 to 75 micromol/l. Arterial pH changes and splanchnic ammonia release were negligible. The renal vein ammonia efflux increased after the protein meal (0.67+/-0.10 to 1.94+/-0.35 micromol/kg bw/min) and to a lesser degree after the amino acid meal (to 1.20+/-0.39 micromol/kg bw/ min). Renal uptake of alanine, and not glutamine, increased stoichiometrically, paralleling the enhanced renal vein ammonia efflux.

CONCLUSIONS

Arterial ammonia increases after a meal in pigs, coinciding with a negligible splanchnic ammonia release, but increased renal vein ammonia efflux. Thus, post-prandial plasma ammonia levels appear to be mainly related to renal ammoniagenesis. Alanine appears to be the main precursor for this renal ammoniagenesis in the pig.

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.

Automated isolation of high-purity plasma albumin for isotope ratio measurements

Measurement of the incorporation of labeled amino acids in plasma albumin, isolated from plasma sampled at different time points after infusion start is a well-known technique to study human albumin synthesis. Unfortunately, no chromatographic method has been described yet, enabling the automated isolation of high-purity albumin from large numbers of plasma samples as is required to study the kinetics of this process. Therefore, we developed a fast protein liquid chromatographic method, capable of processing 200 microliters amounts of plasma in 74 min (injection to injection). The system can run unattended as the FPLC system is connected to a sample processor equipped with a polyether ether ketone (PEEK) sample loop and a cooled sample tray. Albumin isolation was divided into three steps. First, plasma samples were injected onto a 1-ml Blue Sepharose HiTrap affinity column, equilibrated with 50 mmol/l phosphate buffer (pH 7.0). After elution of non-binding protein, switching the solvent to phosphate buffer with 1.5 mol/l sodium chloride eluted albumin. The resulting albumin fraction was desalted on-line by directing it through two consecutive HiTrap 5-ml desalting columns, whereafter it was retained in the system within a 5-ml PTFE loop, connected to a motor value. After switching this valve, thus bypassing the sample loop, the phosphate buffers were changed automatically to Tris buffers. Final purification involved elution of the captured fraction over a 1-ml ion-exchange Resource Q column, using a sodium chloride gradient, ranging from 0 to 0.5 mol/l in Tris buffer (20 mmol/l, pH 7.5). A more than 99% purity of the final albumin fraction was confirmed by capillary electrophoresis.

Myocardial substrate uptake and oxidation during and after routine cardiac surgery

OBJECTIVE

This study was designed to clarify whether myocardial substrate uptake and oxidation change after a period of hypothermic cardioplegic arrest during coronary artery bypass grafting procedures.

METHODS

In 30 patients arterial and coronary sinus blood was sampled and coronary sinus flow measurements were performed before and after sternotomy and 10 minutes, 20 minutes, 50 minutes, and 6 hours after release of the aortic crossclamp. Measurement of free fatty acids, lactate, glucose, oxygen content, and carbon dioxide content in arterial and coronary sinus blood allowed calculations of myocardial substrate use, respiratory quotients, and myocardial oxidation rates of carbohydrates and fat.

RESULTS

Uptake of free fatty acids and lactate was significant throughout the study and did not change in association with release of the crossclamp. Free fatty acid and lactate uptake measured 6 +/- 4 micromol/min and 23 +/- 26 micromol/min, respectively, before crossclamping compared with 8 +/- 7 micromol/min and 19 +/- 21 micromol/min, respectively, after release of the clamp. Glucose uptake was significant only during the first hour after crossclamp release and increased from 7 +/- 50 to 28 +/- 34 micromol/L after crossclamp release. Myocardial oxygen consumption did not change significantly (0.5 +/- 0.2 mmol/L compared with 0.35 +/- 0.2 mmol/L) after release of the crossclamp. Myocardial oxygen extraction ratio decreased from 58% +/- 8% to 41% +/- 13% after crossclamp release. Respiratory quotient increased after crossclamp release (0.85 +/- 0. 2 compared with 1.00 +/- 0.2), which implies that carbohydrate oxidation increased at the expense of free fatty acid oxidation.

CONCLUSION

We conclude that hypothermic cardioplegic arrest during coronary artery bypass graft operations is associated with a transiently increased uptake and oxidation of carbohydrates during the immediate reperfusion phase.

Determination of amino acid isotope enrichment using liquid chromatography-mass spectrometry

The change in amino acid enrichment, an indicator of a change in protein synthesis and/or degradation, is usually measured using gas chromatography-mass spectrometry and/or (GC-combustion) isotope ratio mass spectrometry. Unfortunately, often a complex and sensitive derivatization procedure and/or a large amount of sample is required. Also, these techniques are less suited to study intermediary metabolism, in which the simultaneous application (and thus measurement) of multiple amino acid tracers is preferred. Alternatively, in this study the possibilities of the coupling of liquid chromatography and mass spectrometry were explored, resulting in the measurement of both the concentration and isotope enrichment of o-phthaldialdehyde (OPA)-derivatizated plasma amino acids in one run. This was achieved by the injection of OPA-derivatizated amino acids into an automated HPLC system. After the elution of buffer salts and reagent excess to drain using column switching, the column effluent was directed via a fluorescence detector into a Thermoquest Model LCQ benchtop LC-MS. Mass spectrometric measurements were performed in "zoom-scan" mode, employing multiple scan events if the target components were not baseline separated. Best signal-to-noise ratio's were obtained using the LCQ's electrospray probe in the negative mode. Still, when working under standard conditions the total ion current of OPA-amino acid derivatives eluting at the beginning of the chromatogram (e.g., citrulline, arginine and glycine) was by a factor of 5 lower, compared to components eluting in the last part of the chromatogram (leucine, valine, and ornithine). These differences could be minimized by increasing the temperature of the heated capillary to 260 degrees C and by applying 5% collision energy (between the skimmer and the first octapole) to the first eluting components. A further improvement could not be obtained by the addition of makeup liquids like ammonia, acetic acid, methanol, or acetonitrile (up to 25% of column effluent flow). Considering these results and the fact that the first eluting amino acid derivatives are the most polar ones, we hypothesized that hydration of these components interferes with the ionization process. A linear calibration curve was obtained for both fluorescent response and total ion current (TIC) for all amino acids in the range from 5 to 1000 pmol per injection. The coefficient of variation of the fluorescent response was typically on the order of 1-4%, for the TIC this was between 4 and 9%. However, measurement of isotope ratios requires not only the determination of the area of the base peak, but also of the area of the (enriched) isotopomeric peak(s), having a much lower abundance. Therefore, isotope ratio measurements require the injection of at least 25 pmol of the amino acid derivative of interest (except for ARG 50 pmol) to obtain true ratio's. The accuracy of the isotope enrichment measurement was determined by the injection of a standard containing all major physiological amino acids (400 pmol each) and a standard at physiological concentrations (ranging from 50 pmol (CIT) to 350 pmol (VAL). Standard deviation of the isotopic ratios ranged from 0.1 to 0. 5% for the high (400 pmol) standards and from 0.2 to 0.8% for the low (physiological) standard, which is comparable with GC-MS. A plot of the results against the theoretical values gave a linear curve for all isotopes studied (R2 ranged from 0.9984 to 0.9997). However, the [1-13C]-enriched amino acids measured (LEU, GLY, and VAL) gave a closer agreement to the expected values as was found for [ureido-13C-5,5-2H2]-enriched citrulline and [guanidino-15N2]-enriched arginine. We could not determine whether this was due to the measurement procedure itself or resulting from an instability of the tracers in solution. Nevertheless, the results were reproducible and the theoretical value could be calculated using the tangent of the enrichment curves. (ABSTRACT TRUNCATED)

Upper gastrointestinal bleeding: an ammoniagenic and catabolic event due to the total absence of isoleucine in the haemoglobin molecule

Upper gastrointestinal bleeding causes increased urea concentrations in patients with normal liver function and high ammonia concentrations in patients with impaired liver function. This ammoniagenesis may precipitate encephalopathy. The haemoglobin molecule is unique because it lacks the essential amino acid isoleucine and has high amounts of leucine and valine. Upper gastrointestinal bleeding therefore presents the gut with protein of very low biologic value, which may be the stimulus to induce a cascade of events culminating in net catabolism. This may influence the function of rapidly dividing cells and short half-life proteins. We hypothesize that, following a variceal bleed in a cirrhotic patient, the lack of isoleucine in blood protein is the cause of the exaggerated ammoniagenesis and catabolism. We propose that intravenous administration of isoleucine may serve as a simple therapeutic that transforms blood protein in a balanced protein, resulting in only a short-lived rise in ammonia and urea production, and preventing interference with protein synthesis.

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.

Nutritional depletion and dietary manipulation: effects on the immune response

The association between nutritional depletion and the increased susceptibility for infectious diseases has been recognized for a long time. The complexity of the immune system, however, makes it difficult to unravel the underlying mechanisms. It appears that depletion adversely affects virtually all components of the immune system. This review provides an overview over the specific requirements of substrates by immune cells and the effects of nutritional depletion on various components of the immune response, with special attention to gut-associated lymphoid tissue. The literature concerning effects of dietary interventions with specific nutrients on the immune response is also discussed. Finally, we offer a hypothesis with regard to the improvement of composition of "trauma" nutrition solutions.

Discrepancy between muscle and whole body protein turnover

To understand the mechanisms of muscle wasting, muscle protein turnover is measured. Several techniques are available, including whole body protein turnover measurements and incorporation of tracer into mixed muscle protein. In this brief review, we will focus on these techniques. We conclude that whole body measurements cannot be used as a parameter of muscle protein metabolism. It appears that whole body measurements mainly represent splanchnic protein metabolism. Muscle protein synthesis preferably is measured in individual proteins or protein subfractions.

Infusion of soy and casein protein meals affects interorgan amino acid metabolism and urea kinetics differently in pigs

For routine evaluation of the quality of dietary protein, amino acid scoring patterns were used. Evaluation of this pattern for soy and casein revealed that these proteins are of almost equal quality. However, in vivo studies showed a large difference. To study the biological effects of meals with casein and soy protein, the contributions of individual amino acids to net protein retention and amino acid kinetics in gut, liver and muscle in healthy pigs were investigated. Isonitrogenous enteral nutrition, infused at a rate of 10 mL. kg body wt-1. h-1 and consisting of maltodextrin (137 g/L) with added casein (53 g/L) or soy protein (68 g/L), was given to conscious, healthy female multicathetized pigs (20-22 kg, n = 12). A primed-constant infusion protocol with L-[ring-2,6-3H]phenylalanine, L-[3,4-3H]valine and [15N-15N]urea was used to measure amino acid and urea kinetics in gut, liver and muscle. Measurements were done postabsorptively and 2-6 h after initiation of the enteral nutrition. During the meal, appearance of amino acids into the portal vein and the uptake by the liver was lower with casein infusion. Muscle uptake did not differ. Gut protein synthesis tended to be lower with soy infusion (P = 0.1). Liver protein synthesis and degradation were higher with casein infusion (P < 0.05), while in muscle, soy infusion stimulated protein turnover (P < 0.05). In comparison to the postabsorptive condition, liver urea production was unchanged after casein infusion, while it was significantly increased after soy infusion. These results suggest that the quality of soy protein is inferior to that of casein protein.

[Uremia after hemorrhages in the upper digestive tract]

Haemorrhages in the upper GI tract may lead to severe uraemia and, in patients with liver failure, to hyperammonaemia. The cause of this is not yet sufficiently clear. Recently we observed a decrease in arterial isoleucine levels after intragastric blood administration in pigs. This contrasted with elevated levels of most other amino acids, ammonia and urea. After an isonitrogenous control meal in these pigs all amino acids including isoleucine increased, and urea increased to a lesser extent, suggesting a relationship between the arterial isoleucine decrease and uraemia after gastrointestinal (GI) haemorrhage. Analysis of blood protein showed a complete absence of the essential amino acid isoleucine, making it a protein of low biological value. In additional porcine experiments, uraemia after intragastric blood administration could be prevented by simultaneous intravenous isoleucine administration. This led to the hypothesis that there was a causal relationship between the absence of isoleucine in blood protein and the uraemia and hyperammonaemia observed after GI bleeding. Similar results were seen in patients with intact and with impaired liver functions. These results support the hypothesis that the absence of isoleucine in blood protein causes decreased plasma and tissue isoleucine levels after GI haemorrhage. This might inhibit protein synthesis, and may contribute to uraemia and hyperammonaemia in patients with normal and impaired liver function, respectively. Intravenous isoleucine administration after GI haemorrhage could be beneficial.