Invited comment: short-chain fatty acids: present prospect--future alternative?
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Animals↗
Biomedical subjects
M M Meguid
Publications and source records attributed to M M Meguid.
Short-term effects of fat emulsion on serum lipids in postoperative patients.
The effect of short-term infusion of intravenous fat on serum lipids was assessed in 23 patients who had elective cancer operations and were given 20% Intralipid for 5 days postoperatively as part of a standard total parenteral nutrition regimen. Serum lipids were measured prior to, during and after the 5-day infusion period. The percentage of cholesterol as high-density lipoproteins (HDL) fell from a mean preinfusion value of 34.7 +/- 2.8 to 27.9 +/- 2.5 (p less than 0.05), while the percentage of cholesterol as low-density lipoproteins (LDL) increased from 40.7 +/- 2.2 to 46.8 +/- 3.4 (p less than 0.05). Serum triglycerides fell significantly (p less than 0.01) from 106.2 +/- 13.7 mg/dl to 64.6 +/- 8.8 mg/dl at 3 days, being 85.3 +/- 3.7 mg/dl at 5 days. No significant change in percent cholesterol as very low-density lipoproteins (VLDL), or levels of serum total cholesterol or phospholipids occurred. Lipoprotein X was detectable in six patients after 5 days. To study triglyceride clearance 1.7 g/kg of fat emulsion was infused over 8 hr and serial blood samples obtained. Within 3 hr of stopping the fat infusion, triglyceride levels had fallen to preinfusion values.
Cholesterol↗
Effect of tryptophan and cyproheptadine on food intake.
Whether tryptophan in the usual dose found in total parenteral nutrition (TPN) solutions caused a decrease in food intake was investigated in 16 adult male Fischer 344 rats. A jugular venous catheter was placed, and patency was maintained with a continuous infusion of normal saline at 3 ml/hr. After a 10-day recovery period, eight normal saline control rats were sacrificed and the remaining eight rats were given a parenteral nutrition solution (PN-50) at 3 ml/hr, providing 50% of the rat's daily energy requirement as 5% dextrose and 2% Intralipid. On day 14, study rats were further divided into two subgroups. Subgroup A received tryptophan (180 mg/day) added to the solution for 5 days. Subgroup B received the serotonin-receptor blocker, cyproheptadine 24 mg/kg/day, continuously for 5 days, and on day 16, tryptophan (0.25% = 180 mg/kg/day) was added to the solution for 3 days. Chow and water was continuously available and spontaneous food intake was measured daily. Study rats were sacrificed on day 19. Plasma amino acids and insulin and whole brain biogenic amines were compared with those in control rats using Student's t-test. With administration of PN-50, spontaneous food intake decreased to about 60% compared with the pre-PN level. The addition of tryptophan to the continuous infusion of PN-50 did not decrease spontaneous food intake further.(ABSTRACT TRUNCATED AT 250 WORDS)
Amino Acids↗
Standardized enteral orders attain caloric goals sooner: a prospective study.
Standardized enteral nutrition order forms were introduced listing the enteral formulary, the advancement schedule of formulae, and whether feedings should be given continuously or intermittently. The efficiency of these forms was evaluated prospectively by counting the number of days needed to reach the patient's estimated caloric needs in a total of 113 patients studied 3 months before (pre-group) and 3 months after (post-group) the introduction of the form. When the standardized enteral order forms were used, patients in the post-group reached their caloric goals 3.1 days sooner than did those in the pre-group. Use of standardized enteral nutrition order forms decreases the time needed to reach a patient's estimated caloric needs, thereby achieving effective nutritional therapy sooner.
Adolescent↗
The early cancer anorexia paradigm: changes in plasma free tryptophan and feeding indexes.
Tumor growth is accompanied by an anorexia mediated by humoral factors that appear to influence appetitive mechanisms in the brain. Because tumor resection is followed by resumption of normal food intake, the circulating anorexigenic substance(s) are produced either by the neoplastic tissue or by the host in response to the tumor. Increased levels of plasma free tryptophan and plasma ammonia have been proposed to mediate cancer anorexia. With animal models, it is often difficult to ascertain whether changes in food intake depend upon metabolic changes or the progressively increasing tumor mass per se. The feeding patterns and biochemical changes that occur during tumor growth were evaluated in 96 male Fischer rats that were inoculated with 10(6) methylcholanthrene sarcoma cells or saline (controls). Rats were placed into metabolic cages equipped with an Automated Computerized Rat Eater Meter to continuously determine meal size and meal number. Plasma free tryptophan and ammonia were evaluated 6, 10, 16, 18, 22, and 26 days after tumor inoculation. Anorexia developed by day 17-18, when food intake started to decrease via a decrease in meal size but not meal number and reached 60% of control by day 26. However, long before anorexia developed, free tryptophan was significantly higher 6 days after tumor inoculation, and the greatest increase occurred after 18 days. Ammonia did not differ from control at any time. Data confirm tumor-associated increases in plasma free tryptophan that occurred before the manifestation of anorexia and support a possible role of brain serotonin in cancer anorexia.
Ammonia↗
Gastric emptying in humans: influence of different regimens of parenteral nutrition.
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Adult↗
[Urinary excretion of insulin].
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Age Factors↗
New syringe to prevent mechanical complications of central venous catheter placement.
Prompted by the continued frequency of mechanical complications associated with central venous catheter placement, a more effective and stable and safer catheter placement device has been proposed. Fifteen critically ill surgical patients who required central venous access for total parenteral nutrition (TPN) and fluid management had a central venous catheter placed using the new syringe technique. Despite an equipment-use learning curve, there was no equipment failure. In 14 patients, catheter placement was successful. In one dehydrated patient, repeated attempts at percutaneous infraclavicular subclavian access were not successful, but internal jugular vein access was gained. There were no mechanical or infectious complications in the 15 patients. The new syringe provides a stable platform, reducing the fumbling usual when disconnecting the needle from the syringe and thereby avoiding the potential complications of dislodgment or hub contamination of the introducer needle and air embolism.
Catheterization, Central Venous↗
Bacteriological safety of closed enteral nutrition delivery system.
One of the most commonly reported side effects of enteral tube feedings is diarrhea, at times attributed to the bacterial contamination of tube feedings. A closed enteral delivery system has recently been devised. It consists of a cardboard Tetrapack containing the sterile enteral nutrition formula and and independent sterile administration set; together these constitute a closed Tetrapack-administration set enteral delivery system. The bacteriological safety of this system was evaluated in vitro under controlled laboratory conditions in a series of studies. There was no or bacteriologically insignificant bacterial contamination of the enteral nutrition formula, even with repeated use of one administration set for multiple containers over 24 h. Bacteriological growth in the enteral nutrition formula was directly related to the duration of the hanging time of a Tetrapack container. No bacterial growth occurred with hanging times less than 18 h; insignificant bacterial growth occurred by 24 h. A progressive time-related increase in bacterial growth occurred between 24 and 48 h. Our data indicate that the newly developed closed Tetrapack-administration set enteral delivery system is, and will remain, bacteriologically sterile if each Tetrapack container is allowed to hang for no longer than 24 h.
Bacteria↗
Intestinal obstruction from cecal bezoar; a complication of fiber-containing tube feedings.
Dietary fiber increases stool bulk, regulates bowel transit time, and decreases intraluminal pressure. Because these actions constitute a natural way to stop diarrhea, a frequent problem with tube feedings, enteral tube feeding manufacturers have marketed several fiber-containing formulae. While bulk-forming agents such as fiber may not be appropriate for every tube-fed patient, we were unable to find any published contraindications to the use of fiber-containing enteral products. We present the case of a seriously ill man who received a fiber-containing tube feeding while also getting intestinal motility-suppressing medications. A large fiber bezoar developed, with resultant mesenteric hemorrhage. We conclude that fiber-containing tube feedings are contraindicated in certain types of patients.
Bezoars↗
Clinical use of total nutritional admixtures.
The administration of a single mixture of the components of total parenteral nutrition (TPN) constitutes total nutritional admixture (TNA), the safety and efficacy of which in a variety of clinical settings have been confirmed by controlled trials. According to the nitrogen balance and stable isotope methods, TNA is as efficacious as the old system of three bottles with piggyback intravenous fat emulsion in maintaining body nitrogen mass, visceral protein, and liver function. Also, serum concentrations of electrolytes, trace elements, and vitamins can be maintained adequately using the TNA system. The other advantages are the timesaving to the nursing staff, with its hidden savings in cost; the avoidance of a peripheral catheter solely for the infusion of lipid emulsion in addition to the central catheter for TPN in hospitalized patients; and the facility of use in home nutrition programs. The ease of home use has resulted in a greater degree of patient compliance; thus patients receive a mixed-fuel system while avoiding the hazards of a piggyback infusion, with all its potential complications. Among the perceived disadvantages of TNA are a supposed higher frequency of catheter-related sepsis, a view based on in vitro studies that is not borne out by in vivo studies; catheter occlusion by precipitation of calcium salts; and enhanced ability to clear fat and thus fat tolerance with continuous infusion of lipids. Numerous studies have shown that these concerns are unwarranted.
Bacteria↗
Standardized TPN order form reduces staff time and potential for error.
The Nutrition Support Team developed a standardized parenteral nutrition (PN) order form for the newly introduced total nutritional admixture (TNA) system. The new order form (TNA-Form) is oriented toward the physician, providing prescription guidelines and standing orders for the initiation and discontinuation of PN. The form replaced an older one (TPN-Form) originally designed for pharmacy use. Over two 4-month periods, the usefulness of the new TNA-Form was compared with that of the old TPN-Form, with reviews of the completeness and safety of all PN prescriptions. When prescription errors, errors of dosage, or errors of omission occurred, the pharmacist queried the physician. The number and the nature of the prescription errors per PN order were recorded daily for each patient. With the old TPN-Form, there were 634 prescription errors in 682 patients (93% total error rate). This rate decreased to 116 prescription errors in 1017 patients (11% total error rate) with the new TNA-Form. There were fewer errors in all categories concerning glucose and lipid concentrations, trace elements and vitamins, the use of heparin, infusion rate, and electrolyte concentrations. It was concluded that the new TNA-Form led to a substantial decrease in overall PN prescription errors, particularly errors of omission, resulting in safer, more efficacious, and more uniform provision of PN. The new TNA-Form provided the secondary benefit of an educational tool for housestaff. Because of its broad-based benefits, it was subsequently adopted by two other hospitals in the community.
Drug Prescriptions↗
Identifying the at-risk cancer patient using inadequate oral nutrient intake period.
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Eating↗
Can total parenteral nutrition reverse hypoalbuminemia in oncology patients?
To determine if hypoalbuminemia is a consequence of protein-energy malnutrition rather than an associated feature of cancer, we reviewed results when vigorous nutritional support was given to 13 men and 9 women who had solid tumors (head and neck [10], gastrointestinal [8], other [4]) and an initial serum albumin less than 3.5 g/dl. Patients had received a minimum of 21 days of nutritional support with total parenteral nutrition (TPN) supplying an average daily energy intake of at least 1.5 x basal energy expenditure (BEE). The TPN was started at a dosage commensurate with the patient's estimated postoperative caloric requirements, and patients had received an average of 2358 kcal/day (1.97 x BEE) and 1.54 g of protein/kg of body weight. Patient body weights increased by an average of 2.75 kg during the 21 days of TPN, but there was no statistically significant change in serum albumin, suggesting that factors other than malnutrition were primarily responsible for the hypoalbuminemia. Although TPN is useful as an adjunct in patients with cancer, it may not reverse the hypoalbuminemia commonly seen in this population.
Adult↗
Refinement of central venous cannulation technique.
A further refinement of the improved Seldinger technique of central venous cannulation is described. The method entails inserting the guidewire through a previously created side hole in a standard 5ml plastic syringe. The problems of needle dislodgement, air embolism and blood loss are virtually eliminated with this technique.
Catheterization, Central Venous↗
Clinical applications and cost-effectiveness of All in One.
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Cost-Benefit Analysis↗
Nutrition management of acute intermittent porphyria.
A patient with acute intermittent porphyria is presented to emphasize the relevance of nutrition in its management. Clinical manifestations, diagnosis of acute intermittent porphyria, simplified heme biosynthetic pathway, the glucose effect, and the rationale for giving nutritional therapy for acute intermittent porphyria are discussed.
Adult↗
Plasma amino acid imbalance in patients with lung and breast cancer.
In order to evaluate whether different solid tumors may specifically influence plasma free amino acid (PFAA) profile, PFAA were analysed in seventy-four patients with lung (41 patients) and breast cancer (33 patients) and 28 healthy subjects. In lung cancer patients a significant reduction of gluconeogenic amino acids, threonine, serine, glycine and a significant increase of free tryptophan and glutamic acid was found. In breast cancer patients a significant increase of ornithine, glutamic acid and free tryptophan was found. The comparison of PFAA profiles between lung and breast cancer suggests that different tumors have a different influence on the host's PFAA pattern.
Adult↗