Exploring the effects of high shear blending on lactose and drug using fluidised bed elutriation.

Powder formulations comprising inhalation grade lactose and a mimic drug (cholesterol) were prepared using a high shear blending process for which the total energy input could be quantified. The formulations were fluidised in a classic fluidised bed system, to determine whether blending-induced changes could be determined through either bulk fluidisation behaviour or the characteristics of elutriated fractions from the powder beds. The evolution of the fluidisation regime within the powder beds (Δ pressure vs. superficial gas velocity) and total mass of elutriated material were not sensitive measures to differentiate between blended and unblended samples. However, blended and unblended material could be distinguished by the size distributions of the elutriated fractions. The study also showed that there were no further changes in the size distribution of the elutriated fractions once a chemically homogenous mixture of lactose and drug had been produced. However, further blending beyond this 'point of homogeneity' continued to change the lactose particle size distribution of the bulk powder; this may have implications for blend end point determination for these types of formulation.

Does health education prevent childhood accidents?

In an attempt to test the assumption that health education directed at parents and children can reduce childhood accidents, a controlled study was carried out in Ely , one area of Cardiff. Using conventional health education techniques, the campaign was carried out in June and July 1981 and monitored by the numbers of injured children attending the local Accident and Emergency Department. Comparison of accident numbers in Ely between 1980 and 1981 and between Ely and the whole of Cardiff in 1981 showed no significant change. A slight increase in trivial injuries suggested an increased willingness to attend hospital. There was no change in the age distribution of victims. The benefits of health education and alternative methods of accident prevention are discussed and the need for further research is emphasized.

The effect of dietary carbohydrate and fat on the activities of some enzymes responsible for glycerolipid synthesis in rat liver.

1. Male rats were fed for 14 days on diets containing (by wt.) 53% of starch, or on diets in which 20% of the starch was replaced by sucrose, corn oil or lard. 2. The hepatic activities of the microsomal glycerol phosphate acyltransferase, dihydroxyacetone phosphate acyltransferase, phosphatidate cytidylyltransferase, diacylglycerol acyltransferase and choline phosphotransferase, and of the soluble phosphatidate phosphohydrolase, were measured. 3. The soluble phosphatidate phosphohydrolase activity was higher in those rats fed on lard than in those fed on the starch diet. Choline phosphotransferase activity was higher in the rats fed on corn oil than in those fed on the starch diet. 4. The rate of hepatic glycerolipid synthesis was measured in vivo 1 min after injection of [1,3-3H]glycerol and [1-14C]palmitate into the portal veins. 5. The relative rate of phosphatidylcholine synthesis in vivo was increased after feeding with corn oil and the higher specific activity of choline phosphotransferase may contribute to this result. The equivalent rate of triacylglycerol synthesis was increased by feeding with lard rather than corn oil, and the increased activity of phosphatidate phosphohydrolase may partly explain this. The latter changes probably contribute to the increased concentration of triacylglycerol which other authors have observed in the livers and sera of animals fed on saturated and monounsaturated fats.

The effects of amphiphilic compounds on phosphatidate metabolism.

Amphiphilic cations interact with phosphatidate and thereby change its physical properties. This interaction can redirect phospholipid metabolism. In the presence of Mg2+ amphiphilic cations inhibit the activity of phosphatidate phosphohydrolase and stimulate that of phosphatidate cytidylyltransferase. Increasing the concentration of Mg2+ further, or adding Ca2+ have similar effects, except that Ca2+ does not stimulate phosphatidate cytidylyltransferase activity. Amphiphilic anions reverse the effects caused by the amphiphilic cations. The implication of these results are discussed in relation to the pharmacological effects of amphiphilic cationic drugs.

The effect of chronic diabetes, induced by streptozotocin, on the activities of some enzymes of glycerolipid synthesis in rat liver.

1. Rats were injected with a single dose of 35mg of streptozotocin/kg body wt. They exhibited a diabetes that was characterized by glycosuria, polyuria, polydipsia, hyperphagia, hyperglycaemia, increased concentrations of unesterified fatty acids, glycerol and triacylglycerols in the serum and an increased activity of glucose 6-phosphatase in the liver. 2. After 10 weeks the hepatic activities of the microsomal glycerol phosphate acyltransferase, phosphatidate phosphohydrolase, phosphatidate cytidylyltransferase, diacylglycerol acyltransferase, choline phosphotransferase, CDP-diacylglycerol--inositol phosphatidyltransferase and the soluble phosphatidate phosphohydrolase were measured. 3. The only significant changes were an increase in the activity of the soluble phosphatidate phosphohydrolase and a decrease in that of the CDP-diacylglycerol--inositol phosphatidyltransferase in the diabetic rats. 4. These results are discussed in relation to the control of glycerolipid synthesis.

The effects of acute ethanol feeding and of chronic benfluorex administration on the activities of some enzymes of glycerolipid synthesis in rat liver and adipose tissue.

Rats were treated for 5 days with benfluorex [1-(3-trifluoromethylphenyl)-2-[N-(2-benzoyloxyethyl)amino]propane] or with suspending medium (controls). They were then intubated with an acute intoxicating dose of ethanol or with glucose of equivalent energy content. Treatment of the control rats with ethanol specifically increases the hepatic activity of the soluble phosphatidate phosphohydrolase by about 5-fold in 6 h. The equivalent increase for the benfluorex-treated rats were about 2-fold. The results are discussed in relation to the effects of ethanol and benfluorex on glycerolipid synthesis.

The effects of amphiphilic cationic drugs and inorganic cations on the activity of phosphatidate phosphohydrolase.

1. Phosphatidate phosphohydrolase from the particle-free supernatant of rat liver was assayed by using emulsions of phosphatidate as substrate. 2. The inhibition of the phosphohydrolase by chlorpromazine was of a competitive type with respect to phosphatidate. The potency of various amphiphilic cationic drugs as inhibitors of this reaction was related to their partition coefficients into a phosphatidate emulsion. 3. The effect of chlorpromazine on the phosphohydrolase activity was complementary rather than antagonistic towards Mg2+. Chlorpromazine stimulated the phosphohydrolase activity in the absence of added Mg2+ and was able to replace the requirement for Mg2+. However, at optimum concentrations of Mg2+, chlorpromazine inhibited the reaction, as did Ca2+. The phosphohydrolase activity was also stimulated by Co2+ and to a lesser extent by Mn2+, Fe2+, Fe3+, Ca2+, spermine and spermidine when Mg2+ was not added to the assays. 4. It is concluded that the inhibition of phosphatidate phosphohydrolase by amphiphilic cations can largely be explained by the interaction of these compounds with phosphatidate, which changes the physical properties of the lipid, making it less available for conversion into diacylglycerol. 5. The implications of these results to the effects of amphiphilic cations in redirecting glycerolipid synthesis at the level of phosphatidate are discussed.

The effects of administering N-(2-benzoyloxyethyl) norfenfluramine to rats on the hepatic synthesis of glycerolipids.

N-(2-Benzoyloxyethyl) norfenfluramine (S-780) was administered to rats by stomach tube at a dose of 50 mg kg-1 of body weight. Livers of the rats which were given an acute dose of the drug synthesized more triacylglycerol, phosphatidylcholine and phosphatidylethanolamine from [1,3-3H]glycerol and [14C]palmitate than did those of control rats. The measurements were made by injecting a mixture of the radioactive precursors into the portal veins of anaesthetized rats and freeze clamping a portion of the liver 1 min later. Diffferent results were obtained after treating rats daily with S-780 for 5 days. Liver slices from these rats synthesized less triacylglycerol and relatively more phosphatidylinositol plus phosphatidylserine from [3H]glycerol than did those of control rats. S-780 treatment depressed the hepatic synthesis of phosphatidylcholine and phosphatidylethanolamine as measured in vivo after intrapotal injection of [14C]palmitate and [3H]glycerol. Chronic treatment with S-780 also depressed food intake and lowered liver weight and body weight of rats fed the 41B diet. The results are discussed in relation to the effects of S-780 on the synthesis of glycerolipids.

Drugs affecting the synthesis of glycerides and phospholipids in rat liver. The effects of clofibrate, halofenate, fenfluramine, amphetamine, cinchocaine, chlorpromazine, demethylimipramine, mepyramine and some of their derivatives.

The effects on glycerolipid synthesis of a series of compounds including many drugs were investigated in cell-free preparations and slices of rat liver. p-Chlorobenzoate, p-chlorophenoxyisobutyrate, halofenate, D-amphetamine, adrenaline, procaine and N-[2-(4-chloro-3-sulphamoylbenzoyloxy)ethyl]norfenfluramine had little inhibitory effect on any of the systems investigated. Two amphiphilic anions, clofenapate and 2-(p-chlorophenyl)-2-(m-trifluoromethylphenoxy)acetate, both inhibited glycerol phosphate acyltransferase and diacylglycerol acyltransferase at approx. 1.6 and 0.7 mm respectively. Clofenapate (1 mm) also inhibited the incorporation of glycerol into lipids by rat liver slices without altering the relative proportions of the different lipids synthesized. The amphilic amines, mepyramine, fenfluramine, norfenfluramine, hydroxyethylnorfenfluramine, N-(2-benzoyloxyethyl)norfenfluramine, cinchocaine, chlorpromazine and demethylimipramine inhibited phosphatidate phosphohydrolase by 50% at concentrations between 0.2 and 0.9 mm. The last four compounds inhibited glycerol phosphate acyltransferase by 50% at concentrations between 1 and 2.6 mm. None of the amines examined appeared to be an effective inhibitor of diacylglycerol acyltransferase. Norfenfluramine, hydroxyethylnorfenfluramine and N-(2-benzoyloxyethyl)norfenfluramine produced less inhibition of glycerol incorporation into total lipids than was observed with equimolar clofenapate. The major effect of these amines in liver slices was to inhibit triacylglycerol and phosphatidylcholine synthesis and to produce a marked accumulation of phosphatidate. The results are discussed in terms of the control of glycerolipid synthesis. They partly explain the observed effects of the various drugs on lipid metabolism. The possible use of these compounds as biochemical tools with which to investigate the reactions of glycerolipid synthesis is considered.

The tritium isotope effect of sn-glycerol 3-phosphate oxidase and the effects of clofenapate and N-(2-benzoyloxyethyl)norfenfluramine on the esterification of glycerol phosphate and dihydroxyacetone phosphate by rat liver mitochondria.

1. Owing to a (3)H isotope effect, the mitochondrial sn-glycerol 3-phosphate oxidase (EC 1.1.99.5) had a mean activity which was 8.4 times less with sn-[2-(3)H]-rather than with sn-[1-(14)C]glycerol 3-phosphate as a substrate. 2. A method for measuring the simultaneous synthesis of lipid from glycerol phosphate and dihydroxyacetone phosphate in rat liver mitochondria is described. 3. The lipid synthesized by rat liver mitochondria from sn-[1-(14)C]glycerol 3-phosphate was mainly phosphatidate and lysophosphatidate, whereas that synthesized from dihydroxy[1-(14)C]acetone phosphate was mainly acyldihydroxyacetone phosphate. 4. Additions of NADPH facilitated the conversion of acyldihydroxyacetone phosphate into lysophosphatidate and phosphatidate. 5. Hydrazine (1.4mm) or KCN (1.4mm) inhibited the synthesis of lipids from dihydroxyacetone phosphate but not from glycerol phosphate. 6. Clofenapate (1-2.5mm) inhibited the synthesis of lipids from dihydroxyacetone phosphate but slightly stimulated synthesis from glycerol phosphate. 7. The methanesulphonate of N-(2-benzoyloxyethyl)norfenfluramine, at 0.25-0.75mm, inhibited lipid synthesis from both glycerol phosphate and dihydroxyacetone phosphate.