The urinary excretion of polyethylene glycol as a test for mucosal integrity in children with celiac disease: comparison with other noninvasive tests.

We compared the results of various noninvasive tests with small bowel histology in 61 children with celiac disease. The most sensitive predictors of small bowel histology were serum levels of anti-gliadin antibodies (AGAs) (90%) and the urinary excretion of polyethylene glycol (PEG) (69%). The sensitivity for the fecal fat analysis was 61% and for the D-xylose test 34%. The specificity was 96% for both the PEG and the D-xylose tests, 92% for the fecal fat, and 68% for AGAs. The predictive value of the PEG test was significantly better than that of D-xylose (p less than 0.05). The best combination of tests for the prediction of small bowel histology was the PEG test and the measurement of serum levels of AGAs. Agreement in the results of these two tests helps to time appropriately the second and third small bowel biopsies.

Differential changes in the urinary excretion of two orally administered polyethylene glycol markers (PEG 900 and PEG 4000) in rats after feeding various carbohydrate gelling agents.

The urinary excretion of two orally administered polyethylene glycol markers (PEG 900 and PEG 4000) was measured in rats after feeding various carbohydrate gelling agents. Pectin, guaran, methylcellulose, and carrageenan were added (20% wt/wt) to a fiber-free control diet and were fed for 4 wk prior to the experiment. Excretion of 3H-PEG 900 and 14C-PEG 4000 was measured over a period of 96 h after administration of the markers in the drinking water. In general, the ratio of PEG 4000 to PEG 900 in the urine increased after fiber feeding: from 0.20 in the controls to 0.31, 0.37, 0.29, or 0.27 (medians) in the pectin-, guaran-, methylcellulose-, or carrageenan-fed group, respectively. The pattern of excretion of the two PEG markers in rats fed the fiber-free diet differed from that in the polysaccharide-fed rats. Pectin and guaran, two polysaccharides readily fermented by intestinal bacteria, led to a higher excretion of PEG 4000 but an unaltered excretion of PEG 900, whereas methylcellulose and carrageenan, two polysaccharides more inert against microbial degradation, were associated with a lower excretion of PEG 900 with unchanged excretion of PEG 4000. The study shows that polysaccharides, which may be representative of the soluble portion of dietary fiber, can influence the intestinal permeability of larger molecules. The microbiologically degradable polysaccharides in particular may lead to an increased absorption of larger molecules.

Two-week aerosol inhalation study on polyethylene glycol (PEG) 3350 in F-344 rats.

PEGs in the 3000 to 4000 MW range are used in many pharmaceutical and cosmetic applications; they produce little ocular or dermal irritation and have extremely low acute and subchronic toxicity by oral and dermal routes of administration. However, little information exists on the potential of aerosols of these materials to produce adverse health effects. F-344 rats were exposed to aerosols of PEG 3350 (20% w:w in water) at 0, 109, 567, or 1008 (highest attainable) mg/m3 for 6 hr/d, 5 d/wk for 2 wk. No exposure-related toxicity was found with regard to clinical signs, ophthalmology, serum chemistry, urinalysis, or gross pathology. Exposure-related effects included: a 50% increase in the neutrophil count (males only) at 1008 mg/m3; decreased body weight gain (16%) for both the 567 and 1008 mg/m3 groups (males only); absolute lung weights of both sexes were increased 10 and 18% for the 567 and 1008 mg/m3 groups, respectively. A slight increase in the number of macrophages in the alveoli was the only change observed histologically in all PEG 3350-exposed groups. Therefore, inhalation of aerosols of PEG 3350 at concentrations up to 1008 mg/m3 produced relatively little toxicity in rats, the lung was the target organ, and the no-observable-effect-level was between 109 to 567 mg/m3.

Leakage of intraluminal low molecular weight polyethylene glycol as a marker of small bowel transplant rejection.

To facilitate early detection of small bowel allograft rejection, we correlated transluminal leakage of low molecular weight polyethylene glycol (PEG) with the development of allograft rejection. Vascularized allogeneic and syngeneic jejunal transplants were performed in rats, without immunosuppression. A control group underwent creation of jejunal Thiry-Vella fistulas of similar length. Jejunal segments were perfused with a physiologic solution containing [3H]-PEG-900. At the end of an equilibrium period, an urinary bladder aspirate was collected and [3H]-PEG-900 measured by scintillation counting. Results are expressed as disintegrations per minute per 100 microL urine. Histologic examinations were performed at all experimental time points. Two days following transplantation, urinary PEG levels were elevated in both allogeneic and syngeneic groups (3943 +/- 935 and 4007 +/- 1164, respectively). Four days after the transplant, syngeneic urine PEG levels decreased to 581 +/- 159, and were not significantly different (P greater than .05) from Thiry-Vella controls (635 +/- 145). Syngeneic levels remained at this low level for the rest of the experiment. The allogeneic group continued to show significantly higher levels (P less than .05) compared with syngeneic and Thiry-Vella groups from day 4 until the end of the experiment. These elevated levels most likely represented the development of rejection, preceding the first significant histologic signs of rejection, which were found at six days post-transplant. Detection of transluminal leakage of low molecular weight PEG may be a useful adjunct in monitoring for small bowel transplant rejection.

Laboratory assessment of poisoning with a carbamate insecticide.

We discuss a case of a 17-year-old white male who intentionally ingested a tick and flea insecticide and was admitted to the emergency room unconscious, with signs and symptoms of cholinergic toxicity. Capillary gas chromatography and electron-impact mass fragmentographic analysis of the patient's urine and serum demonstrated the presence of poly-ethylene glycol and propoxur (o-isopropoxyphenyl N-methyl-carbamate), a carbamate-based cholinesterase inhibitor commonly used in insecticides. The patient fully recovered, but only after a complicated hospital course. We also discuss the laboratory assessment and clinical treatment of poisoning with carbamate and organophosphate insecticides.

Gastrointestinal permeability in children with cow's milk allergy: effect of milk challenge and sodium cromoglycate as assessed with polyethyleneglycols (PEG 400 and PEG 1000).

Sixteen children with immediate-type cow's milk allergy were challenged with increasing amounts of cow's milk. Gastrointestinal permeability was investigated before and after challenge by the 6-hr urinary recovery of a mixture of different-sized polyethyleneglycols (PEG 400 and PEG 1000). The results were related to clinical symptoms in the individual patients. The majority of the children displayed changed permeability characteristics after the challenge, both with respect to the maximum uptake of a small test molecule (usually 370 dalton PEG) and/or a large molecule (1074 dalton PEG), and to size-dependent exclusion of probe molecules. When corrected for the dose of milk taken, the children showing the most severe immediate-type symptoms also displayed the greatest alteration of permeability. Treatment with sodium cromoglycate (SCG) before the challenge diminished the effect on the uptake of probe molecules, usually decreased the severity of elicited symptoms, allowing about a ten-fold increase in the milk dose. Cow's milk challenge in healthy children caused only minor permeability changes, whereas challenge in the sensitized subjects significantly changed (increased or decreased) the recovery of a large test molecule. The difference between healthy and allergic subjects was most obvious when correcting for dose of milk ingested. We conclude that oral challenge with cow's milk in allergic subjects affects the mucosal barrier, and peroral treatment with SCG moderates immediate hypersensitivity reactions with respect to both tolerated antigen dose and intestinal permeability properties.

Studies of intestinal permeability in inflammatory diseases using polyethylene glycol 400.

It has been proposed that increased bowel permeability might play a role in the pathogenesis of inflammatory disease. Intestinal permeation was investigated by measuring the 6-hour urinary excretion of polyethylene glycol (PEG) 400 in 40 adult volunteer controls and in patients with inflammatory disease. Of the patients, 15 had Crohn's disease; 7, ulcerative colitis; 2, celiac disease; and 7, rheumatoid arthritis. No significant difference in total urinary excretion over a 6-hour period was found between controls and patients with ulcerative colitis. Patients with Crohn's disease, celiac disease, or with rheumatoid arthritis were found to have significantly decreased urinary excretion of PEG 400. The results of this study indicate that there is no identifiable increase in intestinal permeation as measured by PEG 400 excretion during periods of active inflammatory disease.

Polyethylene glycol polymers of low molecular weight as probes of intestinal permeability. II. Application to infants and children with intestinal disease.

We used a mixture of low molecular weight polymers of polyethylene glycol (PEG) to study intestinal permeability in children with chronic diarrhea. After an oral load, urinary recovery of the longer chain, higher molecular weight polymers was significantly decreased compared with that in healthy adults and infants without disease of the gastrointestinal mucosa. A correlation was observed between clinical severity of disease, histopathologic condition of the small bowel mucosa, and PEG scores. These results indicate that intestinal permeability in children can be studied by noninvasive means and that an assessment of mucosal integrity can be obtained.

Urinary excretion of polyethylene glycol 3350 and sulfate after gut lavage with a polyethylene glycol electrolyte lavage solution.

Ingestion of an electrolyte lavage solution containing polyethylene glycol 3350 and sulfate is an effective method of cleansing the colon for diagnostic studies. Polyethylene glycol and sulfate are considered poorly absorbed from the gastrointestinal tract. Because of the quantities administered, concern exists about potential toxicity of absorption of even a small percentage, particularly for polyethylene glycol. We measured the urinary excretion of both polyethylene glycol and sulfate in normal subjects and inflammatory bowel patients. Absorption of polyethylene glycol can be assessed by measuring recovery in urine, as 85%-96% of an intravenous load is excreted in urine. Similarly, appreciable sulfate absorption would exceed renal tubular reabsorption and result in increased urinary excretion. Mean percent polyethylene glycol load recovered in urine was minimal and similar for normal (0.06%) and inflammatory bowel (0.09%) subjects. Urinary sulfate excretion after lavage was also similar for both groups and was not different from baseline. These results do not suggest the likelihood of toxicity due to polyethylene glycol 3350 or sulfate absorption during gut lavage with this solution.

Clinical pharmacology of polyethylene glycol-L-asparaginase.

Polyethylene glycol (PEG)-L-asparaginase, at doses ranging from 500 to 8000 units/m2, was infused iv over 60 min in 31 patients of whom 27 were evaluable pharmacokinetically. The plasma disappearance of PEG-L-asparaginase is described by a monophasic curve with a mean half-life of 357 +/- 243 hr which is much longer than that of the unconjugated enzyme (half-life of approximately 20 hr). The rate of total clearance (128 +/- 74 ml/m2 X day) is much slower than that of L-asparaginase (2196 +/- 1098 ml/m2 X day). The volume of distribution is 2093 +/- 643 ml/m2, which is similar to that of L-asparaginase, indicating that PEG-L-asparaginase is mainly localized in the plasma. No enzyme could be measured in urine samples taken from nine patients for a period of up to 4 days. Additionally, no enzyme was measurable in one patient's pleural fluid obtained at the end of infusion and 6 days after infusion of a 1000-unit/m2 dose; the corresponding concentrations in plasma were 0.64 and 0.62 units/ml, respectively. In general, the plasma enzyme concentrations at the end of the 1-hr infusion and at 14 days after drug administration were proportional to the dose given. However, in two patients, a sudden disappearance of enzyme levels occurred which preceded anaphylactic reactions during subsequent treatment. A third patient developed severe bronchospasm 30 min after the first dose, but his enzyme levels were within the normal range.

New liquid-chromatographic method for measuring polyethylene glycol in urine.

The various Mr fractions of polyethylene glycol (PEG) in human urine are quantified by "high-pressure" liquid chromatography. A simple preparation step involving lyophilization and chloroform extraction of the sample is required. Aliquots (10 microL) are chromatographed isocratically in equivolume mixtures of methanol and water on a column of styrene divinylbenzene and the refractive index of the effluent is measured. The results vary linearly with the concentrations of standards up to at least 10 g/L, and the six major fractions are clearly identifiable in injected samples containing 2 g or more of total PEG per liter. As little as 4 g/L can be precisely quantified, but for assessing the individual fractions, we recommend a minimum sample concentration of 7 g/L. Analytical recovery of PEG added to urine controls was 90%. Urines collected during 6 h from 11 human subjects after each had ingested 5.6 g of PEG showed no interference from endogenous compounds. We find this method to be a simple, labor-saving means of quantifying urinary PEG in the clinical laboratory.

Safety evaluation of free radical scavengers PEG-catalase and PEG-superoxide dismutase.

Treatment with catalase and SOD (superoxide dismutase) could diminish the damage due to oxygen free radical formation, but these enzymes are rapidly removed from circulation. The covalent attachment of monomethoxypolyethylene glycol (PEG) to catalase and SOD extended their plasma half-lives. Toxicity of PEG-catalase and PEG-SOD was evaluated in mice and rats prior to their use as free radical scavengers. Rodents used in acute, subacute, and subchronic toxicologic studies could tolerate large doses of PEG-catalase and PEG-SOD without developing toxic signs. The conjugates did not affect survival rate, appearance, behavior, food intake, blood chemistry, hematology, or urinalysis. In general, body weight gains, organ weights, and histomorphology were also unaffected. Massive doses of PEG-catalase caused slight weight loss, splenic hypertrophy, and generalized splenic stimulation in mice. Massive doses of PEG-SOD resulted in vacuolation in splenic macrophages in rats. PEG-catalase and PEG-SOD circulated for 3 days and 8 days, respectively, in mice following i.v. or i.m. administration.

Aging-associated increase in intestinal absorption of macromolecules.

The intestinal permeability of aging rats to various molecular weight species of polyethylene glycol 400 (PEG 400) was studied. Animals received a bolus of PEG 400 by oral gavage and urine was collected for 6 h to assess its rate of absorption. Quantitation by gas liquid chromatography revealed that total urinary excretion of PEG 400 increased with aging. 34-week-old rats excreted 34.3% of the administrated dose while 43.6% was excreted in the urine by rats 133 weeks of age. This effect was more pronounced with the higher molecular weight PEG since excretion of the lower molecular weight PEG 282 decreased by 10.5% while PEG 634 excretion increased by 11.4% with aging. The increased permeability of the intestinal tract to higher molecular weight species of PEG may indicate that the intestinal protective barrier to the absorption of potentially harmful environmental substances may be less efficient in aging animals. If similar findings are found in aging humans, they may indicate increased potential for absorption of large antigenic or carcinogenic compounds from the intestinal lumen.

Intestinal permeability in healthy and allergic children before and after sodium-cromoglycate treatment assessed with different-sized polyethyleneglycols (PEG 400 and PEG 1000).

Gastrointestinal permeability was investigated in twenty-two children on two occasions, before and after treatment with sodium cromoglycate. The children were between 8 and 10 years old; half of them were classified as allergic according to history and laboratory tests, and half of them as healthy. The 6-hr urinary recovery of different-sized polyethyleneglycols (PEG 400 and PEG 1000) in combination with a mathematical model was used to assess the intestinal permeability barrier. No significant differences were seen in the first PEG test between healthy and allergic children, although those with gastrointestinal allergy showed a slightly lower, and those with other allergies a slightly higher recovery of the smaller PEGs than seen in the healthy individuals. After treatment with sodium cromoglycate, however, there was a significant decrease in uptake by allergic children, which could indicate that the permeability properties had returned to normal. The PEG method offers a simple, harmless and reproducible method to measure intestinal permeability properties. The change in permeability observed after sodium cromoglycate corresponds well with the clinical experience of usefulness of the drug in some children with food allergy.

A new micromethod for the quantification of low molecular weight oligomers of polyethylene glycol.

We describe a gas-liquid chromatographic technique for quantifying the low molecular weight (Mr 106-634) oligomers of polyethylene glycol (PEG) in clinical specimens. The deionized sample, containing tetra-ethylene glycol as an internal standard, is applied on column. This technique readily quantifies as little as 2.5 micrograms of an individual oligomer; with such a quantity, the coefficient of variation is +/- 2.5 percent (N = 25 analyses). Small volumes (250 microliter) of urine are conveniently analyzed, and a single column can be utilized for the analysis of approximately three hundred specimens. We have analyzed timed urine specimens from humans who received 0.15 g of PEG 400 per kilogram. Individuals varied markedly with regard to the total amount of PEG excreted into the urine; each subject, however, consistently excretes a uniform percentage of the ingested dose. The urinary oligomeric profile of PEG does not vary from subject to subject nor from hour to hour, during the first six hours following oral administration, so that a random urine obtained during this period provides a reliable clinical specimen. This technique should facilitate clinical studies that utilize polyethylene glycol 400 as an index of passive intestinal transport.