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Biomedical subjects

J Booyens

Publications and source records attributed to J Booyens.

At least 19 recordsLinked to original sources
PubMed1992

Margarines and coronary artery disease.

In a previous paper we predicted that health effects of dietary fats in humans would require half a century or more to be understood, instead of the decade or so predicted during 1956 by an Editorial in The Lancet. It would seem that our prediction may have been optimistic since it has now been reported that trans unsaturated fatty acids present in high concentrations in margarines promote hypercholesterolemia in humans. Consequently, there has been a call for the reclassification of dietary fats upon the basis of their hypercholesterolemic properties. Using the latter criterion, therefore, many margarine brands would be classified as coronary artery disease risk foods. The primary adverse metabolic action of trans unsaturated fatty acids is the competitive inhibition of delta-6-desaturase, the hepatic enzyme responsible for the initial metabolic desaturation of the essential fatty acids cis linoleic and cis alpha-linolenic acid. In addition to margarines, many other common foods such as deep-fried foods, many convenience foods and bakery products contain relatively high levels of trans fatty acids. Therefore, since it has become virtually impossible to avoid a consistent, daily dietary intake of trans fatty acids, it would appear that a precautionary, preventative supplementation of the diet with supplements containing the direct metabolic products of delta-6-desaturation of the essential fatty acids, would be prudent. Such supplements are readily available.

Coronary Disease↗
PubMed1990

The effect of gamma-linolenic acid, an in vitro cytostatic substance contained in evening primrose oil, on primary liver cancer. A double-blind placebo controlled trial.

The cytostatic effects of essential fatty acid metabolic intermediates and of some prostaglandins and leukotrienes in vitro have been extensively documented. The essential fatty acids (EFAs) exhibit no side-effects when taken as a dietary supplement, even in large doses. Primary Liver Cancer (PLC) is a fatal disease in our area as it is always multifocal in nature. In vitro studies have shown a cytostatic effect of gamma-linolenic acid (GLA) on primary liver cancer cells. In a double-blind placebo controlled trial, using Evening Primrose Oil (as a source of GLA) as a dietary supplement in PLC patients, no statistically significant effect was observed on survival time or liver size. There was however a statistical significant beneficial effect on Gamma Glutamyl transferase values as a measure of liver function. No side-effects were observed. The large size of tumour and the low doses of GLA used in this trial probably explain the lack of significant effect on survival times.

Antineoplastic Agents↗
PubMed1988

The role of unnatural dietary trans and cis unsaturated fatty acids in the epidemiology of coronary artery disease.

During 1956 the first report on the hypocholesterolemic effect of unsaturated fatty acids of plant and marine origin was published in The Lancet. Consequently it was stated in a Lancet Editorial that hydrogenation of vegetable oils could have contributed to the causation of coronary artery disease and predicted that a decade would probably be required to resolve this question. However, after the lapse of three decades this issue would appear to be no nearer to a clear answer now than it was then. During 1956 hydrogenation was assumed to effect only a reduction in the level of unsaturated fatty acids in the products produced from hydrogenated oils. However, since that time essential fatty acid metabolic pathways to eicosanoids were discovered and described. Also large quantities of unnatural trans and cis unsaturated fatty acids have been shown to form during hydrogenation and these occur in margarines and many other common foods in high concentrations. It has also been shown that these unnatural trans and cis fatty acids block essential fatty acid metabolism by the competitive inhibition of the desaturase enzyme delta-6-desaturase. Therefore some of the possible metabolic mechanisms whereby "hydrogenation plants could have contributed to the causation of a major disease" have become clearer during the last three decades. Despite a recent conclusion by an ad hoc FDA panel that there need be little concern about the effects of trans fatty acids in the American diet on health, it is nevertheless proposed that on the basis of available evidence, unnatural dietary trans and cis unsaturated fatty acid isomers should be regarded as a definite risk factor in the etiology of coronary artery disease.

Coronary Disease↗
PubMed1988

A biochemical analysis of the effects of arachidonic acid on sarcoplasmic reticulum function.

Discontinuous sucrose gradients were used to determine the degree of association between arachidonic acid and sarcoplasmic reticulum vesicle membranes. Fraction analyses showed that arachidonic acid migrated to a different region of the sucrose gradient in the presence of sarcoplasmic reticulum membranes. This could suggest that arachidonic acid was complexed into the membranes. Arrhenius curves representing the temperature dependency of Ca2+-Mg2+-ATPase activity and calcium uptake in the presence and absence of arachidonic acid were constructed. The activation energy for ATPase did not change significantly due to the presence of arachidonic acid. The curve representing control calcium uptake did not show a discontinuity. However, the curve representing calcium uptake in the presence of arachidonic acid showed discontinuities at 18 degrees C and 21 degrees C. Activation energy increased sharply between these temperatures. The results suggest that arachidonic acid reached the critical micellar concentration between these temperatures. Enthalpy decreased in the presence of arachidonic acid. This observation could suggest a transition of the protein-phospholipid complex to a less rigid state since decreased order in the membrane would decrease the energy barrier for activation of ATPase.

Animals↗
PubMed1988

Effects of essential fatty acids on mild to moderate essential hypertension.

A double-blind placebo-controlled study with a crossover design was conducted on 25 non-obese black patients with mild-moderate uncomplicated essential hypertension. They were randomly assigned into two groups. After having received placebo capsules for 4 weeks, they received dietary supplementation with either Efamol-marine (containing desaturated n-6 and n3 essential fatty acids), or sunflower seed and linseed oil capsules for 12 weeks. Thereafter a second 4 weeks placebo phase and a subsequent second 12-week active phase were entered into during which a crossover of the dietary supplementation of the groups was brought about. The mean systolic blood pressure of patients receiving Efamol-marine was significantly lowered after 8 and 12 weeks, while those receiving sunflower/linseed oil supplementation had no significant reduction of blood pressure. This observation may indicate that defective desaturation of the essential fatty acids by the enzyme delta-6-desaturase, could play an important role in the etiology of essential hypertension.

Adult↗
PubMed1986

The presence of trans unsaturated fatty acids in ruminant meat and milk is unnatural.

It is proposed that the presence of large quantities of trans unsaturated fatty acid isomers as final metabolic products of the rumen bacteria and their consequent presence in ruminant tissues and milk is completely unnatural. This results from excessive feeding of domestic ruminants and the consequent passage of bacteria containing partially hydrogenated trans fatty acids into the small intestine. Digestion of such bacteria and the subsequent absorption of the released trans fatty acids could account for their unnatural presence in ruminant tissues and secretion in milk. It is also proposed that the feeding of ruminants, poultry and pigs with unsaturated fatty acid-containing concentrates, could also be a source of trans fatty acids which occur in their tissues.

Animal Feed↗
PubMed1986

Atherogenesis. An epidemiological model based on the presence of unnatural trans and cis isomers of unsaturated fatty acids in the maternal diet and in mothers milk.

The hypothesis that the presence of unnatural trans and cis isomers of unsaturated fatty acids in the maternal diet and in human mothers milk could be responsible for initiating atherosclerosis in utero or in infants is proposed. It is suggested that the key etiological factor involved in the formation of atherosclerotic plaques could be uncontrolled division of smooth muscle cells of the intima resulting from the intracellular excess of linoleic acid and deficiency of its metabolites gamma-linolenic acid and dihomogamma-linolenic acid. This imbalance is brought about by competitive inhibition of the enzyme delta-6-desaturase by unnatural trans and cis unsaturated fatty acids. Delta-6-desaturase is the enzyme responsible for converting linoleic acid to dihomogamma-linolenic acid. The cellular presence of unnatural trans and cis isomers of unsaturated fatty acids would therefore enhance increased levels of linoleic acid and deficiency of its metabolites gamma-linolenic acid and dihomogamma-linolenic acid. It is proposed that prophylaxis against the effects of delta-6-desaturase inhibition could be achieved by the adoption of an Eskimo-like diet containing the essential fatty acid metabolites gamma-linolenic acid and/or dihomogamma-linolenic acid and eicosapentaenoic acid per se in high concentrations.

Arteriosclerosis↗
PubMed1986

The Eskimo diet. Prophylactic effects ascribed to the balanced presence of natural cis unsaturated fatty acids and to the absence of unnatural trans and cis isomers of unsaturated fatty acids.

In addition to the well recognised roles of eicosapentaenoic acid and possibly docosahexaenoic acid, there are two other major important, but unrecognised, features of the traditional Eskimo staple diet namely that it contains the unsaturated fatty acids (UFA) cis oleic, cis linoleic and cis alpha-linolenic as well as their respective C20 and C22 metabolites in physiologically optimal concentrations and, it is virtually totally devoid of unnatural and potentially hazardous trans and cis isomers of these fatty acids. Large quantities of unnatural trans and cis isomers of UFA are found in the Western diet as partially hydrogenated UFA in many foods. These isomers are formed during the manufacture of margarines and related compounds, as food contaminants during excessive heating of cooking oils for deep-frying and other excessive heat-requiring mass food preparation procedures and it is suggested, as the result of excessive feeding with an unnatural diet of ruminants and non-ruminants for increased meat and/or milk production and of poultry for increased egg and/or meat production. These isomers have been shown to display potentially hazardous metabolic effects which include the competitive inhibition of UFA metabolism at various steps and have been causally implicated in the etiology of ischemic heart disease and cancer. It is suggested that the myth of the safety of trans fatty acids arises from misinterpretation of the observation that increasing dietary cis linoleic acid reduces the toxic effects of trans UFA. It is suggested that the decrease of 20% in the ischemic heart disease mortality in the USA during the past two decades is directly related to a shift in the dietary ratio of unnatural trans and cis UFA isomers: cis linoleic acid in favour of the latter. It is predicted that this ratio will be found to correlate with ischemic heart disease patterns in other countries. Eskimos consume the bulk of their food frozen, raw or dried, seldom boiled, but never deep-fried or after exposure to excessive heat. Moreover the proportionality of cis UFA and their metabolites in their traditional staple diet would render gross tissue UFA utilization relatively independent of desaturase enzyme activity. In the Eskimo tissues these enzymes would function to make the minute, critical UFA metabolic adjustments required to ensure the presence of structural UFA in membranes in functionally optimal quantities and, ensure the synthesis of eicosanoids from dihomogamma-linolenic acid, arachidonic acid and eicosapentaenoic acid in balanced, optimal physiological concentrations for the genetic make-up of Eskimos.(ABSTRACT TRUNCATED AT 400 WORDS)

Dietary Fats↗
PubMed1985

Effects of digoxin and acetyl-digitoxin on basal and CO2-stimulated ventilation.

Eight healthy volunteers were studied to ascertain the effect of digoxin and the relatively more lipophylic cardiac glycoside, acetyl-digitoxin on ventilation. Baseline ventilation as well as the response to the inspiration of 2.2% and 4.8% carbon dioxide were assessed. Digoxin produced a depression of minute volume and oxygen consumption whereas acetyl-digitoxin produced the opposite effect. This could be the result of a relatively greater vagomimetic effect with digoxin and a greater symphatomimetic effect with acetyl-digitoxin. These findings might have clinical implications in cardiac patients who have pulmonary disease.

Acetyldigitoxins↗
PubMed1985

The use of drugs for the inhibition of prostaglandin or leukotriene synthesis from arachidonic acid is theoretically hazardous.

It would appear that it has become almost common practice to regard arachidonic acid (AA) as the sole precursor of eicosanoids. The fact that both dihomogamma-linolenic acid (DGLA) and eicosapentaenoic acid (EPA) give rise to distinct families of eicosanoids is commonly almost completely ignored. Elevated tissue levels of AA eicosanoids have been found in and have been implicated in the etiology of a number of diseases. Drugs which selectively block AA mobilization or its eicosanoid metabolism have therefore been developed for therapeutic use in these conditions. The fact that such drugs will also simultaneously block the eicosanoid metabolism from DGLA as well as from EPA is also commonly ignored. It is suggested that the profoundly adverse side-effects displayed by some of these drugs, resulting in some instances in their withdrawal from use, could be the direct result of their concomitant action of interfering with the eicosanoid metabolism of DGLA and EPA. It is further suggested that, before the interactions between the eicosanoids derived from AA and those derived from DGLA and EPA are understood, the use of drugs for the manipulation of AA eicosanoid metabolism in isolation, could be hazardous. This implies that all such drugs currently in use are to be regarded as experimental and provisionally toxic in terms of their effects on the whole system of eicosanoid metabolism. Thus even drugs which have been passed by the FDA and similar Drug Control Councils require total re-evaluation especially in view of the fact that the non-steroidal anti-inflammatory drugs are often prescribed for chronic conditions which require therapy for several years.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Dietary fats and cancer.

The mono-unsaturated non-essential fatty acid oleic acid (OA) has been shown to stimulate malignant cell proliferation in culture significantly. In contrast, the essential fatty acids (EFAs) linoleic acid (LA) and alpha-linolenic acid (ALA) and their longer chain metabolic derivatives have been shown to have potent proliferation suppressive effects on malignant cells in culture. OA is normally synthesized in the body and present in most vegetable oils and therefore also in most experimental polyunsaturated fatty acid diets used for assessing the effects of dietary fatty acids on tumorigenesis in rats. Dietary OA could therefore specifically account for the general observation that diets containing polyunsaturated fatty acids (PUFAs) are tumorigenic (1). It has been repeatedly demonstrated that many EFAs and EFA metabolites suppress proliferation of a wide range of malignant cells in culture. These cytotoxic effects of EFAs do not inhibit the proliferation of nonmalignant cultured cells. The EFAs which have proliferation-suppression activities are components of cell membranes and many are also eicosanoid precursors. It is proposed that the membranes of malignant cells are inherently unstable. Thus the EFAs may have effects which either fluidise or stabilise these membranes. This results in either cytolysis or inhibition of proliferation. The relative quantities of the different EFAs may be critical for these effects. Eicosanoid metabolites may further compound these actions. It is suggested that one pathway for these actions could be a metabolic imbalance of EFA metabolites and their eicosanoid products. This would arise due to a combination of inhibited desaturase enzymes and a concomitant free cellular supply of dietary arachidonic acid (AA). This imbalance also could be causally involved in the promotion of malignancy. A simple procedure, which only involves dietary supplementation with gamma-linolenic acid (GLA) and eicosapentaenoic acid (EPA), is proposed as prophylaxis against the possible tumorigenic effect of dietary fats. "By some estimates, as much as 90% of all cancer in humans has been attributed to various environmental factors, including diet. The evidence reviewed by the committee suggests that cancers of most of the major sites are influenced by dietary patterns. The committee concluded that of all the dietary components it studied, the combined epidemiological and experimental evidence is most suggestive for a causal relationship between fat intake and the occurrence of cancer" - (1).

Animals↗
PubMed1985

Chronic arachidonic acid eicosanoid imbalance: a common feature in coronary artery disease, hypercholesterolemia, cancer and other important diseases. Significance of desaturase enzyme inhibition and of the arachidonic acid desaturase-independent pathway.

A chronic imbalance between the essential fatty acid metabolites arachidonic acid, gamma-linolenic acid and eicosapentaenoic acid and of their respective eicosanoid derivatives appears to be implicated in the etiology of many intractable disease. Most notable among these are coronary artery disease, cancer and chronic inflammation. The factors leading to such an imbalance and their relatively simple prophylactic and therapeutic circumvention are discussed briefly.

Arachidonic Acids↗