Howard R. Sloan

Dietary and Drug Treatment of Primary Hyperlipoproteinemia

Abstract The first step in the management of primary hyperlipidemia is its translation into hyperlipoproteinemia, which can be done by measuring the plasma cholesterol and triglyceride concentratio...

Beta-galactosidase in tissue culture derived from human skin and bone marrow. Enzyme defect in GM1 gangliosidosis.

Extract: β-Galactosidase activities were determined in fibroblast preparations derived from the bone marrow and skin of a patient with GM1 gangliosidosis and from 11 control subjects. Two β-Galactosidase substrates were employed in these studies: ganglioside GM1, labled with tritium in the terminal galactose by a new procedure, and o-nitrophenly-β-galactopyranoside. The GM1-β-galactosidase activity in the cells of the patient was reduced 17- to 30-fold compared with the activity in the cells of the control subjects; also, the cells of the patient exhibited an 11- to 30-fold depression in onitrophenyl-β-galactosidase activity (ONP-β-galactosidase). These results demonstrated that fibroblasts cultured from an affected subject might be employed for diagnostic purposes. The GM1-and o-nitrophenyl-β-galactosidase activities of fibroblasts cultured from amniotic fluid have also been determined; o-nitrophenly-βgalactosidase activities ranged from 61 to 153 units/106 cells and the GM1-βgalactosidase activities varied between 45 and 95 units/108 cells.Speculation: Determination of GM1-β-galactosdase activity in fibroblasts cultured from skin may permit the detction of individuals heterozygous for GM1 gangliosdosis. The presnce of a β-galactosidase capable of releasing the terminal galactose from ganglioside GM1 in fibroblasts derived from amniotic fluid offers a basis for possible intrauterine diabnosis of GM1 ganagliosidosis.

Early Changes in the Permeability of the Blood-Brain Barrier Produced by Toxins Associated with Liver Failure

ABSTRACT: Our study was designed to determine whether substances that appear in the serum during the course of liver failure have a detrimental effect on the passive permeability of the blood-brain [blood-cerebrospinal fluid (CSF)] barrier. Lactic acid, octanoic acid, and ammonia were infused into rabbits for 4 h. The permeability changes of the blood-brain barrier were quantified by infusing polyethylene glycol 400 (PEG 400) and measuring the quantity and average mol wt of the PEG 400 that entered the CSF. The lipid solubility and effective diffusional radius of the PEG molecules were also quantified to provide greater precision for measurements using this probe. None of the animals receiving toxic infusions became seriously ill during the infusions. Low dose infusions of lactic acid, octanoic acid, and ammonia increased the effective pore diameter of the blood-brain barrier from 7.3 A to an average of 8.5 Å. The amount of PEG entering the CSF increased from 1.7 to 4.0 (p < 0.025), 4.7 (p < 0.025), and 6.7 (p < 0.001) mmol/L, respectively. Rabbits with galactosamine-induced liver failure had 10.1 mmol/L PEG 400 in the CSF (p > 0.001) before any evidence of cerebral edema. These changes occur soon after these toxins accumulate in the plasma and may alone or together with other toxins account for the permeability changes that allow seurotoxic substances to enter the brain during hepatic disease and encephalopathies such as Reyes syndrome.

The contribution of salivary amylase to glucose polymer hydrolysis in premature infants.

ABSTRACT. To determine whether salivary amylase of premature infants can function as a surrogate for pancreatic amylase, we evaluated its production in the infant, acid resistance, and hydrolytic potency in a simulated oropharyngeal, gastric, and intestinal environment. The activity of salivary amylase in 11 prematures varied between 1 and 33 U/ml; the isozymic profile and acid resistance of the premature salivary amylase were identical to those of the enzyme of adults. A “modular” formula containing 7 g/dl of a 14C labeled long chain glucose polymer with degrees of polymerization ranging between 18 and 29 glucose units was prepared. Salivary amylase, 1.1 U/ml, was added to this formula. The progressive breakdown of the 14C polymers as the milk was subjected to oropharyngeal, gastric, and intestinal phase environments was evaluated by quantifying the liberation of short-chain oligomers from the 14C labeled substrates. The gastric pH was varied between 2 and 5 and the gastric incubation time was either 5 or 180 min. Substantial gastric phase breakdown only occurred after 3 h of exposure at the higher pHs of 4 (12%) and 5 (32%). During the intestinal phase, salivary amylase activity resumed. Prior gastric phase pH affected ultimate intestinal phase breakdown, p<0.001; after 5-min gastric phases at pHs ranging from 2 to 5, the intestinal phase breakdown ranged from 17 to 55%. We conclude that the limited salivary amylase in the saliva of premature infants can produce significant glucose polymer digestion in both the stomach and small intestine but the digestion falls substantially short of that accomplished by usual concentrations of pancreatic amylase.

The Jejunal Absorption of Glucose Oligomers in the Absence of Pancreatic Enzymes

Summary: We compared the absorption of carbohydrate from solutions of glucose oligomers and glucose in jejunal Thiry-Vella fistulae, a preparation deprived of pancreatic secretions. The studies were performed with two concentrations (90 and 360 mg/dl) of both glucose and the glucose oligomers. Carbohydrate absorption from glucose solutions (33.1 × 2.8, 115.9 × 8.9 μg/cm/min) was significantly greater (P < 0.025; P < 0.005) than that from oligomer solutions (26.6 × 2.1 and 92.4 × 9.0 μg/cm/min). Thin-layer analyses of the perfusates demonstrate digestion of oligomers with a chain length up to eleven and suggest digestion of oligomers of even greater chain length. Atrophy of the jejunal mucosa occurred over the course of the study as evidenced by a decrease in the ratio of villous height to crypt depth from 3.8 to 0.3, and by a 80% decrease in the activity of maltase, sucrase, and lactase. Atrophy was accompanied by a significant decline in the absorption of both glucose oligomers (P < 0.005) and glucose (P < 0.01) from the more concentrated solutions but the decrement in absorption of both carbohydrates was similar, glucose oligomers, 79.3 × 19.4 μg/cm/min; and glucose, 69.8 × 14 μg/cm/min (P > 0.20). Water absorption was enhanced by both carbohydrates, but there was no demonstrable difference between solutions of glucose and glucose oligomers. The osmolality of the solutions clearly influenced water absorption (P < 0.025) but failed to effect the absorption of carbohydrates.Speculation: In patients with pancreatic insufficiency, solutions of glucose oligomers with low osmolality may provide an adequate source of calories. Although glucose is better absorbed than glucose oligomers from a short segment of jejunum, the length of the small intestine should be adequate to compensate for this difference.~h~ absorption of the glucose oligomers may be a function of polymer length and therefore studies with subfractions separated according to chain length will demonstrate which oligomers are most efficiently absorbed. such information may provide the theoretical hasis for the construction of an ideal carbohydrate supplement for patients with pancreatic insufficiency.

Large Scale Preparation of Selected Glucose Oligomers and Polymers by Gel Filtration Chromatography

A method for isolating relatively large quantities of glucose oligomer and polymer subfractions from a corn starch hydrolysate is described. Employing large columns of Bio-Gel P-2 (40-80 microns) at room temperature, we can prepare each day 0.5 to 1.2 grams of oligomeric fractions containing three to four adjacent homologues. The columns are homemade, require no flow adapters, and are operated by gravity elution with water as the solvent. The means for avoiding and overcoming potential difficulties, such as microbial contamination and declining flow rate, are described. With the use of the described method, we can operate a single column continuously for up to twelve months.

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.

Comparison of the clinical and biochemical effect of increased alpha-linolenic acid in a safflower oil intravenous fat emulsion.

We report the results of a randomized comparison of two intravenous safflower oil (fat) emulsions in neonates who required total parenteral nutrition. The fat emulsions differed only in their content of α-linolenic acid: in one emulsion the α-linolenic acid content of the oil was 0.1% of fatty acids, while in the other emulsion the α-linolenic acid content of the oil was 3.0 ± 1.5% (SD) of fatty acids. Group 1 and 2 patients received the “low” and “high” α-linolenic acid emulsions, respectively. Ten patients were studied in each group. The mean daily fat dosage was 1.70 g/kg in patients of Group 1 and 1.56 g/kg in those of Group 2. No significant difference in the clinical effects of either fat emulsion could be detected between the two study groups. Both emulsions prevented or corrected biochemical signs of essential fatty acid deficiency. The major statistically significant difference between study groups was in the level of α-linolenic acid and its metabolite, eicosapentaenoic acid. After 2 weeks of fat therapy, these fatty acids were increased in the high α-linolenic acid group; however, another metabolite of linolenic acid, docosahexaenoic acid, decreased during intravenous fat therapy in both study groups. Both study groups had significantly decreased arachidonic acid levels and increased linoleic to arachidonic acid ratios.

Lactose flux occurs by differing mechanisms in the colon and jejunum of newborn piglets

ABSTRACT: The unidirectional flux of 10− and 40-mM lactose was studied in newborn porcine jejunum and colon mounted in Ussing chambers. Polyethylene glycol 400 was used to measure passive paracellular permeability. The mucosal-to-serosal flux and the tissue accumulation of labeled lactose from the colon was similar to that of lactose-derived glucose from the jejunum. However, only jejunum showed a lactose-stimulated increase in short-circuit current. In jejunum, glucose was the sole sugar identified in the serosal bath, whereas in colon, only intact lactose was identified. Despite colonic lactose flux, polyethylene glycol oligomers were not found in the serosal bath, suggesting that they do not share the same route of absorption. Colonic lactose transport was nonsaturable between 1 and 40 mM. Under nongradient conditions, no net colonic lactose transport was observed. Cumulatively, these data suggest that the colon, unlike the jejunum, does not contain a glucose-galactose sodium cotransporter. The colon of the newborn piglet transports intact lactose at a flux equal to that of lactose-derived glucose by the small intestine, but by a different mechanism that is as yet undefined.

Large scale production of glucose oligomers and polymers for physiological studies in humans

Methods for isolating relatively large quantities of glucose oligomer and polymer subfractions from a partial corn starch hydrolysate (PCSH) are described. To ensure that the products are suitable for physiological studies in humans, potentially toxic substances were excluded from the preparative processes. For long chain glucose polymer fractions with degrees of polymerization (DP) averaging 43 glucose units, we employed molecular filtration through Amicon YM5 membranes. For fractions containing glucose oligomers with DPs 3 through 8, we employed yeast fermentation followed by ethanol fractionation.