Slow gastric emptying in type I diabetes: relation to autonomic and peripheral neuropathy, blood glucose, and glycemic control

OBJECTIVE

To investigate whether autonomic neuropathy or hyperglycemia plays a crucial etiological role in gastric retention of ingesta frequently found in type I diabetic patients.

RESEARCH DESIGN AND METHODS

We investigated the gastric emptying of a radiolabeled semisolid 1,168 kJ meal in 38 female and 45 male patients (age 18-75 years; illness duration 3-46 years). None took drugs affecting gastrointestinal motility. Fasted patients underwent tests of cardiovascular autonomic and peripheral nerve function. Blood glucose levels were determined before and after the scintigraphic recording of gastric emptying.

RESULTS

The percentage of meal remaining in the stomach at the end of the 50-min recording time was related significantly to the patients' degree of cardiovascular autonomic neuropathy [r (81) = 0.235, P < 0.028] but not to their degree of peripheral neuropathy, preprandial blood glucose level, HbA1c indicative of glycemic control, diabetes duration, and age. The patients' mean residual percentage of meal was significantly greater than that of 48 healthy subjects, that is, 71.1 +/- 15.1 vs. 53.5 +/- 13.1% [means +/- SD; t (129) = 6.48, P < 0.0001]. The healthy individuals' mean residual percentage + 2 SD was exceeded in 22 patients.

CONCLUSIONS

Slow gastric emptying in patients with type I diabetes seems related to the degree of autonomic neuropathy but not to peripheral neuropathy, actual blood glucose, and glycemic control.

Simplified preparation of a refined milk formula comparable to rat's milk: influence of the formula on development of the gut and brain in artificially reared rat pups

BACKGROUND

Milk formulas for artificially reared (AR) rat pups are mostly based on complex cow's milk products, prepared by laborious and time-consuming processes. The aim of this study was to develop a simplified procedure for preparing a refined formula and to examine its influences on gut and brain development.

METHODS

The formula comprised a combination of purified cow's casein and whey proteins, five kinds of edible oil, minerals, and vitamins. Detailed analyses showed that the composition of macro- and micro-nutrients, osmolarity, and pH of the new formula closely resembled those of rat's milk. Rat pups, each with an intragastric cannula implanted at age 5 days, were artificially reared for the following 10-15 days.

RESULTS

The body weight gain of AR pups matched that of mother-reared (MR) pups. Histoplanimetrical analyses showed that the small intestine in AR pups was more developed in relation to area of a transverse section, number and length of villi, and thickness of tunica muscularis than that of MR pups. Fat components in the formula influenced the fatty acid composition and the cholesterol-to-phospholipid ratio in the small intestinal microvillus membrane (MVM) of AR pups, but not the MVM fluidity. Brain weight was not significantly different between the two groups at age 15-20 days.

CONCLUSION

This formula is useful for artificial rearing of rats and for identifying dietary components contributing to metabolic adaptation during the suckling period.

Admixture of a multivitamin preparation to parenteral nutrition: the major contributor to in vitro generation of peroxides

BACKGROUND

Peroxides have been reported to contaminate lipid emulsions and amino acid solutions used in total parenteral nutrition (TPN). This is particularly disturbing in newborn infants who are prone to several diseases related to immature defense mechanisms against oxidative challenges. It is not clear whether the antioxidants in multivitamins help protect parenteral nutrients against the hazards of oxidation.

OBJECTIVE

To evaluate the role of a multivitamin preparation (MVI) on the actual peroxide load received by patients on TPN.

METHODOLOGY

The generation of peroxides in parenteral nutrition was tested first using test solutions. We compared the relative contribution of commercially available amino acid solutions, a lipid emulsion, and MVI on the level of peroxides in clinically relevant TPN solutions. Second, we measured the level of peroxides actually infused at the bedside. In both circumstances, the effects of time and light exposure were isolated. The level of peroxides was determined by a colorimetric technique and expressed as microM equivalents tert-butyl hydroperoxide (microM = TBH).

RESULTS

Even when protected from light, the addition of MVI produced a 10-fold increase in peroxides (mean +/- SEM, n = 3, 19 +/- 4 to 189 +/- 8 microM = TBH at 4 h) in the fat-free TPN solution and a fourfold increase (64 +/- 6 to 244 +/- 8 microM = TBH at 4 h) in the lipid-containing TPN solution. A dose-response relationship was found between the concentration of MVI and peroxide levels. The effect of light was the strongest in the presence of multivitamins. The amino acid solutions had a relative inhibitory effect on the generation of peroxides by MVI, which varied (from 54 +/- 1% to 72 +/- 1%) all according to the amino acid blend. In parenterally fed premature infants, protecting the intravenous set from light decreased the load of infused peroxides (146 +/- 15 vs 215 +/- 24 microM = TBH).

CONCLUSIONS

The lipid emulsion had a significant but minor additive effect compared with the multivitamin preparation, which was the major contributor to the generation of peroxides. Protection from photooxidation is not sufficient to prevent peroxidation of TPN solutions. Contrary to what one would expect, increasing the concentration of MVI will lead to a greater generation of peroxides, suggesting that the essential antioxidants in MVI do not have antiperoxide properties.

Diet-induced changes in liver and bile but not brain fatty acids can be predicted from differences in plasma phospholipid fatty acids in formula- and milk-fed piglets

The fatty acid composition of plasma phospholipids differs between infants fed formula and infants fed human milk, but the extent to which this is accompanied by differences in tissue phospholipid fatty acids is unclear. This paper describes analysis of plasma, liver and brain fatty acids from piglets fed one of seven formulas, varying in saturated, monounsaturated, (n-6) and (n-3) fatty acids or sow milk from birth for 18 d. Bile fatty acids were analyzed because they are secreted from liver and may be an important source of fatty acids for intestinal lipoprotein synthesis. The results were used to determine the relation between diet-related differences in plasma phospholipid fatty acids and those in brain, liver and bile. Where significant associations were found, prediction limits were constructed to assess the usefulness of analysis of plasma phospholipid fatty acids to predict diet-induced changes in tissue fatty acids. The proportions (g/100 g fatty acids) of 16:0, 18:0, 18:1, 18:2(n-6) and 20:4(n-6) in plasma phospholipids were significantly associated with the proportions of the same fatty acids in liver and bile, but not brain. The results show a reasonably precise, predictable association between plasma and liver, and plasma and bile fatty acids. Brain 20:4(n-6) and 22:6(n-3), in contrast, were not reliably associated with plasma phospholipid 20:4(n-6) and 22:6(n-3) for piglets fed milk or formula providing about 1.5% energy as 18:3(n-3).

Rapid separation of soybean globulins by reversed-phase high-performance liquid chromatography

A rapid separation of the main soybean proteins (7S and 11S globulins) was carried out by reversed-phase high-performance liquid chromatography. For this purpose, a linear binary gradient acetonitrile--water--0.1% trifluoroacetic acid, at a flow-rate of 1 ml/min and 50 degrees C temperature was designed. Under the experimental conditions of this work, it was possible to separate five peaks corresponding to the globulins from a soybean protein isolate in 9 min. The characterization of soybean proteins was accomplished by analyzing the 7S and 11S purified fractions obtained from a soybean protein isolate. The method was applied to the separation of soybean proteins from commercial foodstuffs: soybean flour, textured soybean and soybean milks.

Aluminum in enteral nutrition formulas and parenteral solutions

BACKGROUND

To examine the aluminum content of several commercially available enteral nutrition formulas and parenteral solutions.

METHODS

Twelve enteral nutrition formulas and 10 parenteral solutions were commonly used in routine clinical care of patients and obtained from different medical companies in Turkey. The aluminum contents were determined by electrothermal atomic absorption spectrophotometry.

RESULTS

We found that aluminum concentration in the enteral nutrition formulas and the parenteral solutions to range from 87.6 to 961.2 ng/mL and 58.4 to 1232.0 ng/mL, respectively.

CONCLUSIONS

Careful clinical and biochemical monitoring are warranted to determine whether it will be necessary to eliminate aluminum contamination of enteral and parenteral preparations used in patients, particularly infants, with reduced kidney function who may be at risk for aluminum intoxication.

Response of severely malnourished patients to preoperative parenteral nutrition: a randomized clinical trial of water and sodium restriction

Preoperative parenteral nutrition (PPN) may be beneficial for severely malnourished patients who are candidates for a major elective surgical procedure. The response to PPN, however, has not been thoroughly investigated. Expansion of the extracellular water compartment may occur in some patients, producing a further decrease in the serum albumin concentration and increasing the postoperative complications. Our aims were to investigate the occurrence of and factors associated with water and sodium retention during PPN and its impact on postoperative respiratory complications. Forty-one patients with gastrointestinal cancer and severe malnutrition (weight loss > 15% and/or serum albumin < 35 g/L) were randomly allocated to two groups receiving isocaloric isonitrogenous PPN for 10 d. The Standard PPN Group (SG, n = 19) received 70% of nonprotein calories as glucose, 45 cc of water.kg-1.d-1, and 140 mEq/d of sodium chloride; and the Modified Group (MG, n = 22) received 70% of calories as fat, 30 cc of water.kg-1.d-1, and no sodium. Weight and albumin changes, diuresis, sodium and water balances, and postoperative complications were recorded. At the end of PPN, the SG showed a higher weight gain (0.8 versus -1.5 kg, P = 0.0001) and albumin decrease (-0.7 versus 2.3 g/L, P = 0.006). Diuresis and sodium balance were greater in the SG (1,230 versus 959 mL/d, P = 0.003 and 40 versus -27 mEq/d, P = 0.001). Weight changes correlated with water (r2 = 0.46, P = 0.001) and sodium (r2 = 0.62, P = 0.0001) balances. Inappropriate responses to PPN in both groups (expansion or depletion of the extracellular water compartment) were associated with a significant increase in pulmonary postoperative complications. During PPN, extracellular water expansion--as determined by increasing weight and lowering of the serum albumin concentration--and aggressive fluid therapy to treat water and sodium depletion seem crucial to the development of postoperative respiratory complications.

Effects of n-3 and n-6 fatty acids on plasma eicosanoids and liver antioxidant enzymes in rats receiving total parenteral nutrition

The effect of total parenteral nutrition (TPN) enriched with n-3 or n-6 fatty acids on the concentration of plasma eicosanoids was evaluated in rats. Rats were divided into three groups: the control group (n = 6) was fed a chow diet and infused with saline only. Two experimental groups (n = 11, 13) received TPN solutions at an energy level of 30 kcal/100g body weight with 40% energy provided as fat. The experimental groups were maintained on TPN for a period of 7 d. The basal TPN solutions were isonitrogenous and identical in nutrient composition except for differences in lipid source. One experimental group received a safflower oil emulsion, whereas the other group received a fish oil emulsion. At the end of the experimental period, plasma 6-keto prostaglandin F1 alpha, thromboxane B2, bleeding time, lipid peroxidation products, and antioxidant enzymes of liver were analyzed. The results demonstrated that the fish oil group had lower 6-keto prostaglandin F1 alpha concentration than the safflower oil group. Also, plasma thromboxane B2 was the lowest in the fish oil group among the three groups. There was no difference in bleeding time among the groups. With regard to liver lipid peroxidation products, malondialdehyde concentration was not higher in the fish oil group, whereas superoxide dismutase and glutathione peroxidase activities were lower in the fish oil group compared with the control and safflower oil groups. The results suggest that TPN prepared with fish oil fat emulsion causes less accumulation of lipid peroxidation products in the liver of rats, and may be beneficial in preventing platelet aggregation.

Adult tube feeding formulas

Adult tube feeding formulas vary considerably with respect to composition, administration, and cost. Selecting the best product for patients requires a careful analysis of specific patient requirements and resources.

Percutaneous endoscopic gastrostomy

Percutaneous endoscopic gastrostomy (PEG) is now the technique of choice for patients requiring long-term enteral feeding. It is a good method for feeding patients with neurological dysphagia and can safely be kept in situ for long periods. PEG feeding requires a multidisciplinary approach, involving doctors, nurses, pharmacists, speech therapists, dieticians and carers. The insertion of a PEG, which requires two operators and two endoscopy nurses, is described in full. Feeding can commence after a few hours. Various types of feed and feed-ing patterns are described and their relative merits discussed. Although psychological problems may occur following PEG insertion, the procedure is usually well accepted by patients.

Determination of selenium in infant formula and enteral formula by dry ash graphite furnace atomic absorption spectrometry with deuterium background correction

A method was developed to determine selenium in infant formula using a graphite furnace equipped with deuterium background correction after dry ashing. The method circumvents the use of perchloric acid, 2,3-diaminonapthalene (DAN) and hydride generation without the use of Zeeman background correction. Twelve commercial infant and enteral formulas and corresponding spiked products (30-500 ng) were analyzed in triplicate for Se to evaluate this method. All test portions were digested on a hot plate after addition of magnesium nitrate-nitric acid. Following heating, digests were evaporated to dryness and placed in a 500 degrees C muffle furnace for 30 min to complete ashing. All Se was converted to Se+4 by dissolving the ash in HCl (5 + 1) and holding the solution for 20 min in a 60 degrees C water bath. Se+4 was subsequently reduced to Se(zero) with ascorbic acid and collected on a membrane filter. The membrane filters were digested in a small volume of nitric acid in a microwave oven. Following digestion, contents of the vessels were diluted and analyzed for Se by graphite furnace atomic absorption spectrometry. Selenium standards in starch or in unfortified formula containing trace levels of Se were carried through the entire process. The recovery range for Se was 85-127%, and analyzed reference materials fell within their certified range for Se. This method is as sensitive (detection limit 0.44 ng Se/g) as methods reported in the literature and may be applicable to other foods.

Enteral nutrition and the critically ill

Critically ill patients invariably require nutritional intervention. Traditionally, enteral nutrition has not been widely employed in this patient population. This is due in part to the success of present-day parenteral nutrition, and to difficulties encountered with enteral feeding. Recent evidence has demonstrated that enteral is preferable to parenteral nutrition in terms of cost, complications, gut mucosal maintenance, and metabolic and immune function. Enterally administered nutritional support can and should be utilised as the preferred route of nourishment for the critically ill. The appropriate choice of access and formula, as well as a rational strategy for implementation, should improve the likelihood of success. This article describes the unique features of critical illness as they pertain to nutritional support, the benefits of enteral nutrition, and the obstacles to success, and offers suggestions which may improve the ability to provide nutrients adequately via the intestinal tract.

Effects of in-line filtration on lipid particle size distribution in total nutrient admixtures

BACKGROUND

The recent Food and Drug Administration Safety Alert recommends in-line filtration for all total parenteral nutrition admixtures. Although rigid crystalline particulates can be effectively removed by in-line filters, the fate of flexible lipid droplets (LDs) enlarged through electromechanical destabilization is less clear. Lipid globules > 5 microns could lodge in the pulmonary microvasculature and produce an embolic syndrome. Recent evidence suggests that TNAs (Total Nutrient Admixtures) with LDs of 5 microns or more constituting > 0.4% of the final fat concentration are unstable.

METHODS

Six pairs of 1.5-L TNA dispersions of varying degrees of stability were prepared in duplicate (n = 12) and studied over 30 hours. The number of enlarged fat globules was assessed by laser light extinction for all LDs > or = 1.75 microns at 0, 6, 24, and 30 hours after preparation. After LD assessments at time 0, admixtures were placed in a temperature-controlled chamber at 25 degrees C +/- 0.1 degree C. At 6 hours, a simulated patient infusion was begun using a 1.2-microns filter at a continuous flow rate of 55 mL/h. Pre- and postfiltration samples were taken at 6, 24, and 30 hours, equal to times 0, 18, and 24 hours of the simulated infusion. A repeated measure two-way analysis of variance assessing treatment and time was performed. Dependent variable analyses included number-weighting of fat globules as > 5 microns (LD1), total number > or = 1.75 microns (LD2), LD1-LD2 ratio (as %), and volume-weighted percent of fat (PFAT) > 5 microns.

RESULTS

In all cases, time was a significant factor and was an expected finding as the stability of all extemporaneously prepared admixtures deteriorates with time. Of the number-weighted variables, a significant postfiltrate reduction was observed in LD1 (p = .041), LD2 (p < .001), and LD1-LD2 ratio (p < .0001). Of greatest clinical importance, the volume-weighted PFAT > 5 microns was significantly reduced by the in-line filter (p = .029).

CONCLUSIONS

The TNA1 1.2-microns filter significantly reduced the total number and concentration of enlarged fat globules. The higher LD1-LD2 ratio may reflect the effects of filtration on electrically destabilized fat globules. However, total exposure to unstable and very large LDs was significantly reduced, suggesting that in-line TNA filtration should be a standard part of nutrition therapy.

The ratio of n-6 to n-3 polyunsaturated fatty acids in the rat diet alters serum lipid levels and lymphocyte functions

Previous studies have reported that feeding rats diets rich in fish oils, which contain high proportions of the n-3 polyunsaturated fatty acids (PUFA) eicosapentaenoic and docosahexaenoic acids, results in lowering of blood lipid levels and suppression of lymphocyte functions tested ex vivo and in vivo. The effects of other n-3 PUFA, such as alpha-linolenic acid, which is found in high proportions in linseed oil, are not as well documented. Therefore, in the present study, weanling male rats were fed for six weeks on one of five high-fat (20% by weight) diets made by mixing together sunflower and linseed oils; the resulting blends had n-6/n-3 PUFA ratios of 112.5:1 (pure sunflower oil), 14.8:1, 6.5:1, 0.81:1, and 0.33:1 (pure linseed oil); the levels of all other components in the diet were identical. The final body weight and total dissectable fat were lowest in rats fed the pure linseed oil diet. Serum cholesterol, triacylglycerol and nonesterified fatty acid concentrations decreased as the n-6/n-3 PUFA ratio of the diet decreased. The fatty acid composition of the serum and of spleen lymphocytes was influenced by the diet fed-there was a progressive decrease in the proportions of linoleic and arachidonic acids and a progressive increase in the proportion of alpha-linolenic acid as the n-6/n-3 PUFA ratio of the diet decreased. Eicosapentaenoic and docosahexaenoic acids were detected in the serum but not in spleen lymphocytes. Inclusion of alpha-linolenic acid in the diet resulted in significant suppression of spleen lymphocyte proliferation in response to the T-cell mitogen concanavalin A and in spleen lymphocyte natural killer cell activity, both measured ex vivo. The localized graft vs. host response, a measure of cell-mediated immunity in vivo, progressively decreased as the n-6/n-3 PUFA ratio of the diet decreased. Thus, this study shows that dietary alpha-linolenic acid results in lowered blood lipid levels and suppressed lymphocyte functions ex vivo and in vivo. With respect to these effects, alpha-linolenic acid is as potent as dietary fish oil.

Glutamine content of protein and peptide-based enteral products

BACKGROUND

Glutamine is a conditionally essential amino acid for patients with severe catabolic illness, intestinal dysfunction, or immunodeficiency syndromes. Glutamine is a natural component in many enteral preparations, yet lacking methodology hampers its quantitative determination in dietary products.

OBJECTIVE

The present study was assigned to assess glutamine contents in selected enteral products by using a newly developed method enabling the assessment of protein/peptide bound glutamine.

METHODS

Fourteen commercially available enteral diets (10 protein based and 4 peptide based) were investigated. After removal of interfering fat and carbohydrates, the nitrogen content of the purified preparations was determined by chemiluminescence and protein/peptide bound glutamine was assessed using a three-step procedure; by using a novel prehydrolysis derivatization technique with bis(1,1-trifluoroacetoxy)iodobenzene, glutamine is converted to acid stable diaminobutyric acid. The derivatives are hydrolyzed with a new microwave technology, and subsequently the amino acid composition is determined by reversed phase-high-performance liquid chromatography after dansyl-chloride derivatization.

RESULTS

The content in the protein-based preparations varied between 5.2 and 8.1 g/16 g nitrogen. In the peptide-based products, considerably lower glutamine contents were measured (1.3 to 5.6 g/16 g nitrogen).

CONCLUSION

In the present study, we report for the first time glutamine contents in ready to use enteral products. The daily amount might be satisfactory for healthy individuals but probably not sufficient for the adequate support of the stressed patient. Reliable assessment of glutamine in enteral formulae is a prerequisite t perform clinical studies investigating glutamine requirements in the catabolic state.

Phospholipid-rich particles in commercial parenteral fat emulsions. An overview

In parenteral nutrition, the infusion of a fat EMU supplies both concentrated energy and covers the essential fatty acid requirements, the basic objective being to mimic as well as possible the input of chylomicrons into the blood. This objective is well met by the TAGRP of the EMU, which behave as true chylomicrons. However, commercial EMU also contain an excess of emulsifier in the form of PLRP. The number of these PLRP depends directly on the PL/TAG ratio of the EMU. They differ from the TAGRP by their composition (PL vs TAG and PL), their structure (PL in bilayer versus monolayer), and their granulometry (mean diameter 70-100 nm for PL vs 200-500 nm). The metabolic fate of the PLRP is similar in several ways to that of the TAGRP: exchanges of PL with the PL of the different cellular membranes and of the lipoproteins; captation of free CH from these same structures; and enrichment in apolipoproteins. However, because the TAGRP are the preferred substrates of the lipolytic enzymes, their clearance is much more rapid (half-life < 1 h) than that of the PLRP. As the infusion is continued, the PLRP end up accumulating and being transformed into LP-X (free CH/PL = 1; half-life of several days). As soon as the EMU is infused, the PLRP enter into competition with the TAGRP, in the lipolysis process as well as for sites of binding and for catabolism. The sites for catabolism of the two types of PAR are not the same: adipose tissues and muscles utilize the fatty acids and monoacylglycerols released by the lipolysis of the TAGRP; hepatocytes take up their remnants; the RES and the hepatocytes participate in the catabolism of the PLRP and the LP-X. Thus, prolonged infusion of EMU rich in PLRP leads to a hypercholesterolemia, or at least a dyslipoproteinemia, due to elevated LP-X, associated with a depletion of cells in CH, stimulating thus tissue cholesterogenesis. However, parenteral nutrition has evolved towards the utilization of EMU with a low PL/TAG ratio (availability of 30% formula) and less rapid delivery. For these reasons, the hypercholesterolemias that used to be observed with the 10% EMU have become much less spectacular or have even disappeared. It is interesting to note that patients on prolonged TPN, in particular those with a short small intestine, have weak cholesterolemia, reflecting a lowering of HDL and LDL not masked by elevated LP-X. At present, it seems difficult to produce sufficiently stable parenteral EMU devoid of PLRP. Notwithstanding, all the observations made since the introduction of the EMU in TPN are in favour of the use of PLRP-poor EMU. It is clear that the 10% formulas, and generally those with a PL/TAG ratio of 12/100, are ill-advised, especially in patients with a retarded clearance of circulating lipids.

The use of modular nutrients in pediatrics

BACKGROUND

Nutrient modules are commonly used by pediatricians and dietitians. There is no readily available current literature to which those using nutrient modules can refer. Therefore, we review nutrient module composition, module use in pediatrics, and complications associated with the use of nutrient modules.

METHODS

Using an online database, Meduline, we searched the literature from 1996 through 1995.

RESULTS

Nutrient modules are single or multiple nutrients that can be combined with a diet to add nutrients or to change the composition of the diet. These nutrients exist as a food or as medically compounded elements of a diet but alone are not complete foods.

DISCUSSION

The addition of modules to a diet can alter the composition of a diet so that a single nutrient may become deficient and the diet cannot support normal growth and development. With use of nutrient modules, diets can be prepared to meet the specific needs of children with common or rare nutritional problems.

CONCLUSION

Health care providers who use nutrient modules must understand the importance of diet composition and the careful monitoring of pediatric patients.

Stability of heparin anticoagulant activity over time in parenteral nutrition solutions

BACKGROUND

Heparin added to parenteral nutrition solutions may decrease the incidence of central venous thrombosis in patients receiving home parenteral nutrition. However, there are little data regarding the stability of heparin over time under conditions similar to those associated with home parenteral nutrition: low concentrations of heparin stored in solutions containing amino acids and high concentrations of dextrose for more than 24 hours.

METHODS

The activity of porcine mucosal heparin was measured over time using an antifactor Xa assay in six IV solutions: four parenteral nutrition solutions containing 25% dextrose; 5% amino acids; trace elements; electrolytes; and 3000, 5000, 10,000, or 20,000 units/L of heparin; one solution of 25% dextrose and 5000 units/L heparin; and one solution of 0.9% saline and 5000 units/L heparin.

RESULTS

In all solutions except 25% dextrose (without amino acids and additives), heparin activity remained stable within 4% of baseline up to 28 days. In the 25% dextrose solution, heparin activity declined by 3%, 6%, and 11% at 14, 21, and 28 days, respectively.

CONCLUSION

Heparin activity was stable over time in the normal saline and parenteral nutrition solutions and decreased slightly from 2 to 4 weeks in the dextrose-containing solution. Based on these data, when home parenteral nutrition is administered containing components similar to the solutions used in this study, heparin may be added at the time of preparation of the home parenteral nutrition solution rather than just before administration, with no resultant loss of heparin activity over time [corrected].

Carbohydrate and alcohol content of 200 oral liquid medications for use in patients receiving ketogenic diets

OBJECTIVE

The ketogenic diet is used in patients with intractable seizure disorders. To maintain a ketotic state, patients on this diet must maintain a strict low-carbohydrate intake. Because these patients often require medication, and because many pharmaceutical products (especially liquid formulations) contain significant quantities of carbohydrates, it is important that each drug product be evaluated before proceeding with the ketogenic diet. The purpose of this study was to compile the carbohydrate content of oral liquid products for patients on or considering a ketogenic diet.

METHODS

A list of 200 oral liquid drug products and their manufacturers was compiled using the Children's Health Care-Minneapolis pharmacy purchasing database, the Physicians' Desk Reference, and previously published lists of oral liquid medications. Manufacturers were contacted either by telephone or by letter and asked specifically about the sucrose, fructose, sorbitol, glycerin, and alcohol content of these liquid formulations.

RESULTS

The carbohydrate and alcohol content of 200 oral liquid products was determined and shown in an accompanying table.

CONCLUSIONS

Many oral liquid medications contain significant amounts of carbohydrate. Tablet and capsule formulations are preferred when possible. To date, it has been difficult to quantify the carbohydrate content of liquid medications because of unavailability of this information. The carbohydrate content of 200 oral liquid medications is provided here to assist health care practitioners, patients, and care givers in designing drug regimens low in carbohydrates for patients on or considering a ketogenic diet.

Polyunsaturated fatty acids status in blood, heart, liver, intestine, retina and brain of newborn piglets fed either sow milk or a milk replacer diet

Docosahexaenoic (DHA) and arachidonic acids (20:4n-6) are deposited in large amounts in the developing neural tissues of the fetus and neonate. The suckling infants receive both fatty acids via the maternal milk, whereas formula-fed infants must synthesize them de novo from their respective precursors, linoleic (18:2n-6) and alpha-linolenic (18:3n-3) acids. We compared the lipid status of 14- and 21-day-old piglets fed either natural milk or infant formula, with special emphasis on the resulting DHA and 20:4n-6 levels in the neural tissues. The two diets presented similar ratios of precursors (18:2n-6/18:3n-3 = 14-16). The sow milk contained 20:4n-6 (0.6% of total fatty acids) and very low levels of DHA (< 0.1%). Formula feeding resulted in higher deposition of DHA in the brain than sow milk feeding, whereas the brain content of 20:4n-6 was not altered. The brain DHA level was negatively correlated with the 18:2n-6/18:3n-3 ratio in the red blood cells (RBC). In contrast, it was not correlated with the DHA concentration in the circulating lipids. The results indicate that the very low amount of DHA in sow milk has no effect on the accumulation of DHA in the piglet's brain, and that natural milk and formula are not equivalent with respect to precursor bio-availability and processing. This difference could be the result of a higher absorption rate and/or the metabolic sparing of formula 18:3n-3. The data support the view that the balance between the essential precursors in the circulating lipids is of vital importance for optimal deposition of DHA in the developing neural tissues.

Impact of enteral feeding of a glutamine-supplemented formula on the hypoaminoacidemic response in trauma patients

Plasma amino acid concentrations were measured during fasting and after 3 days of enteral feeding in 16 trauma patients on a glutamine-supplemented diet and 14 patients on an isonitrogenous control diet. During fasting, total amino acids, including glutamine, were depressed by 50% and this was attributed to a reduction in both essential and nonessential amino acids. The essential amino acid concentrations increased in both groups after feeding. The nonessential amino acid concentrations also increased in the control group but not in the glutamine group during feeding. Repletion of the glutamine extracellular pool was not evident after an average intake of 27.1 g per day of glutamine for 3 days. Nitrogen balance was similar for the two groups during feeding. We conclude that in this study, enteral glutamine did not increase the glutamine plasma concentration. In addition, both formulas improved the hypoaminoacidemia of essential amino acids but only the control diet improved the nonessential amino acids plasma concentration.

Vitamin D in infant formula and enteral products by liquid chromatography: collaborative study

Results from a collaborative study of a new liquid chromatographic (LC) method for determination of vitamin D in infant formulas and enteral products are presented. Each of 15 laboratories was provided with 11 blind duplicate samples covering a range of approximately 200-500 International Units/quart (normal dilution), a system suitability sample, and the U.S. Pharmacopeia ergo- and cholecalciferol standards. Product types included liquid and powder forms of milk (whey and casein), soy, and hydrolyzed protein-based infant formulas and enteral products. The method includes a single liquid-liquid extraction following saponification, solid-phase extraction, and then concentration by evaporation. An isocratic, nonaqueous, chromatographic system with reversed-phase, zero endcapped C18 column, and UV detector set at 265 nm are used. Statistical evaluation of data from participating laboratories show the average reproducibility and repeatability of the method across all samples to be excellent, with RSDR and RSDr values of 13.48 and 9.44, respectively, after elimination of outliers. The LC method for determination of vitamin D in infant formulas and enteral products has been adopted by AOAC INTERNATIONAL.