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Biomedical subjects

P Singer

Publications and source records attributed to P Singer.

At least 199 records · Page 11Linked to original sources
PubMed1984

Decrease of arachidonic acid in phosphatidylcholine from renal medulla of SHR after feeding a linoleic and linolenic acid-rich diet.

Linoleic acid-rich (LAR), linolenic acid-rich (LNAR) and linoleic acid-deficient (LAD) diets in spontaneously hypertensive rats (SHR) and normotensive rats (NR) resulted in various changes in n-6 and n-3 fatty acids of lipids in renal medulla. After LAR diets the percentage of linoleic (LA) and arachidonic acids (AA) was high only in triglycerides (TG) and free fatty acids (FFA). In phosphatidylethanolamine (PE) LA was increased after LAR diet, whereas AA remained unchanged. In phosphatidylcholine (PC) LA was higher, but AA appeared lower as compared to LAD fed SHR. After LNAR diet linolenic (LNA) and eicosapentaenoic acids (EPA) were increased, but AA appeared significantly lower. Consequently, the lowest percentage of AA was found after LNAR diet. Blood pressure could not be influenced by the diets.

Animals↗
PubMed1984

Alterations of linoleic, arachidonic and eicosapentaenoic acids in renal cortex and medulla of SHR during the onset of hypertension.

104 spontaneously hypertensive rats (SHR) and 107 normotensive control rats (WR) fed a commercial diet were sacrificed at 4, 8, 26 and 52 weeks of age. The kidneys were immediately removed and carefully separated into cortex and medulla. In general, the triglyceride levels in renal medulla appeared higher when compared with the cortex. On the other hand, phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were usually higher in the cortex and increased with age. In the kidneys of SHR at 8 weeks of age, i.e. during the development of hypertension, the percentage of linoleic acid (LA) in triglycerides and of arachidonic acid (AA) in PC was decreased. This was associated with an increase of AA in free fatty acids (FFA), indicating an enhanced activity of phospholipase A2. Furthermore, a fall of eicosapentaenoic acid (EPA) in triglycerides, FFA, PC and PE of kidneys in SHR at 8 weeks of age could be found. The data suggest that systematic alterations in the availability of individual polyunsaturated fatty acids in various renal lipids might be related to the onset of hypertension in SHR. Age-dependent changes in enzymes involved in prostaglandin formation should be considered as an adaptive mechanism which is insufficient to reduce or abolish genetically determined hypertension in SHR.

Aging↗
PubMed1984

Clinical studies on lipid and blood pressure lowering effect of eicosa-pentaenoic acid-rich diet.

15 volunteers were put on a mackerel (MD) and herring diet (HD) for 2 weeks in a cross-over design. At the end of the dietary periods eicosa-pentaenoic acid (EPA) was predominantly incorporated into cholesterol esters (CE), whereas docosahexaenoic acid (DHA) appeared more in triglycerides (TG). This was more pronounced after MD as compared to HD. After MD a significant decrease of serum TG, total cholesterol (C) and lecithin cholesterol acyl transferase (LCAT) activity could be observed returning to the initial levels 3 months later. After HD only a decrease of LCAT was significant. In addition, a marked decrease in blood pressure (BP) was associated with lower plasma noradrenaline levels after MD, but not after HD. In 14 patients with mild essential hypertension an enhanced percentage of EPA and DHA in the lipids of VLDL, LDL and HDL could be confirmed. After MD serum TG, C, LDL-C and LCAT were significantly decreased, whereas HDL-C appeared increased. After HD the changes were of minor degree. Systolic BP was significantly lower at the end of MD. In 8 patients with type IV and V hyperlipoproteinemia (HLP) similar changes could be seen, the most striking finding being a fall in serum TG, especially if initial values were extraordinarily high. The data suggest a beneficial effect of MD on several parameters known as risk factors of atherosclerosis.

Adult↗
PubMed1984

Negative correlation of eicosapentaenoic acid and lipid accumulation in hepatocytes of diabetics.

In 130 type I and II diabetics with normal serum lipids and in 98 diabetics with type IIa-V hyperlipoproteinemia (HLP), liver biopsies were performed if clinically indicated. During histological examinations of one half of the biopsy specimen lipid droplet size was classified into 4 categories, which were proved by morphometric studies, independent of the amount of fat. From the remaining part the fatty acid composition of triglycerides was analyzed by gas liquid chromatography. Moreover, the fatty acid pattern of serum triglycerides and subcutaneous adipose tissue from the abdominal wall was estimated. The percentage of eicosapentaenoic acid (EPA) in triglycerides of normal diabetic liver (no visible fat) was remarkably high (greater than 30 per cent). In adipose tissue it was low (less than 1 per cent). In serum triglycerides it remained between liver and depot fat (about 3 per cent). EPA decreased with rising lipid droplet size in hepatocytes. Liver diseases, like chronic hepatitis, had no influence on the results. One year after clofibrate treatment, the percentage of EPA in liver appeared increased. In adipose tissue, however, it remained constant. In general, EPA in liver and serum triglycerides was higher in diabetics with normal serum lipids as compared to diabetics with HLP. The decreased availability of EPA in liver and serum triglycerides of diabetics with HLP suggests a significant correlation between this fatty acid and hepatic lipid accumulation which itself is associated with diseases known as risk factors of atherosclerosis.

Adipose Tissue↗
PubMed1984

Mono-, di- and triglycerides in serum of spontaneously hypertensive and normotensive rats in relation to age.

Serum triglycerides appeared significantly lower in spontaneously hypertensive as compared to normotensive rats except in 8-week-old animals. Tri-, di and monoglycerides decreased continuously with age in the former but revealed only a transient fall in the latter. The remarkably high portion of partial glycerides (about 30% of total glycerides) in serum should be considered in all studies on lipolysis in rats.

Aging↗
PubMed1983

The treatment of newborn infants with major handicaps. A survey of obstetricians and paediatricians in Victoria.

We report the results of a survey of the attitudes and practices of obstetricians and paediatricians in Victoria with respect to the treatment of infants born with severe handicaps. Eighty-seven obstetricians and 111 paediatricians either completed questionnaires or agreed to be interviewed during the period 1981-1982. The treatment of severely handicapped infants is a matter of increasing concern to members both of the public and of the medical profession. The principal question is whether every infant should have its life prolonged by all available means, or whether some infants born with severe handicaps should be allowed to die. We attempt to identify areas of consensus and disagreement. We do not propound any particular point of view--our intention is rather to stimulate debate.

Attitude of Health Personnel↗
PubMed1983

Role of electrical activity in axotomy-induced increased glucose use.

Glucose use as demonstrated by 2-deoxyglucose autoradiography increases in the hypoglossal nucleus after axotomy of the hypoglossal nerve. There are several possible explanations for this increase, including increased energy metabolism to support increased protein, RNA, and lipid synthesis during regeneration or, alternatively, increased electrical activity associated with the site of nerve transection or alterations in the neurolemma. To evaluate the possible role of electrical activity, we recorded spike activity in the hypoglossal nucleus after axotomy and evaluated glucose uptake in the hypoglossal nucleus after xylocaine application to the proximal nerve stump. There was no evidence from these experiments that an increased number of action potentials is responsible for the increased glucose use after axotomy.

Action Potentials↗
PubMed1983

Lipid and blood pressure-lowering effect of mackerel diet in man.

Fifteen healthy volunteers were put on a mackerel and herring diet, consisting of a prescribed daily isocaloric regimen in a cross-over design, for 2 weeks. Eicosapentaenoic acid (EPA - C20:5, n-3) was predominantly incorporated into cholesterol esters, whereas docosahexaenoic acid (C22:6, n-3) appeared more in serum triglycerides, indicating that the function of the latter may be different from that of EPA. After mackerel ingestion, serum triglycerides, total cholesterol and lecithin cholesterol acyl transferase (LCAT) activity were significantly decreased, returning to basal levels 3 months later. Low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol and postheparin lipolytic activity (PHLA) remained unchanged at the end of the mackerel diet. Generally, after the herring diet the differences were minor, only LCAT activity being significantly decreased. A markedly lower systolic and diastolic blood pressure at the end of the mackerel period could be observed. After herring diet a slight diminution of blood pressure was not significant. Accordingly, plasma noradrenaline was only significantly decreased at the end of the mackerel period. Dopamine-beta-hydroxylase (DBH) activity in serum had no differences before, during and after the study. From the data presented it can be said that a mackerel diet exerts a beneficial influence on cardiovascular risk.

Adult↗
PubMed1983

Changes of polyunsaturated fatty acids in serum lipids of spontaneously hypertensive rats during the onset of high blood pressure.

The fatty acid pattern of serum triglycerides and cholesterol esters has been estimated in spontaneously hypertensive rats (SHR) and normotensive Wistar rats (WR) at 4, 5, 6, 7, and 8 weeks of age. The percentage of linoleic acid (LA) was lower in SHR when compared with WR, but increased with age in both strains. Arachidonic acid (AA) showed an abrupt fall in SHR and WR at 5 weeks of age in comparison to 4 week old rats. The fall was more pronounced in serum triglycerides of the former and in cholesterol esters of the latter. The changes in AA occurred prior to the onset of hypertension in SHR. From the data it can be concluded that the formation of AA from LA might be dependent on age being quantitatively different in SHR and WR. Furthermore, eicosapentaenoic acid (EPA) appeared lower in SHR than in age-related WR. Docosapentaenoic and docosahexaenoic acids also revealed a marked decrease in rats between 4 and 5 weeks of age indicating that individual polyunsaturated fatty acids (PUFA) change in a different manner which might be relevant to the development of high blood pressure in SHR.

Age Factors↗
PubMed1983

In vitro fertilisation: the major issues.

In vitro fertilisation is now an established technique for treating some forms of infertility, yet it remains ethically controversial. New developments, such as embryo donation and embryo freezing, have led to further discussion. We briefly discuss the ethical aspects of IVF, focusing on the issues of resource allocation, the 'unnaturalness' of the procedure, the moral status of the embryo, surrogate motherhood, and restrictions on access to IVF. We argue that, on the whole, IVF is an ethically justifiable method of assisting infertile couples.

Adoption↗
PubMed1983

Effect of glycerol on peripheral nerve: an experimental study.

Håkanson's method of treatment of trigeminal neuralgia by injecting glycerol into the trigeminal cistern is being used in a few clinical centers with encouraging results. We undertook this experimental study utilizing a rat sciatic nerve model to elucidate the mode of action of glycerol. Fifty-six rats were divided into three groups. The topical application of pure glycerol on the sciatic nerve was used in Group I. The intraneural injection of glycerol was used in Group II. The effect of graded concentrations of glycerol was studied in Group III. Physiological saline was the control in Groups I and II. The animals were killed at the end of either 1 or 3 1/2 weeks after the application of glycerol, and the sciatic nerves were examined with light and electron microscopy. Our results show that myelin disintegration and axonolysis occur with glycerol application. Myelinated and unmyelinated fibers are affected at random, although the most striking histological changes were seen in the myelinated fibers.

Animals↗
PubMed1983

[Deliberate poisoning with paraquat, death in less than 24 hours].

This paper describes a case of deliberate massive ingestion of Paraquat (over 300 mg/Kg). Evolution is toward a circulatory insufficiency with metabolic acidosis, hyperglycemia, and early death (18 hours). Severe pulmonary failure would have been expected, but not appeared. Autopsy revealed patchy necrosis of the liver but no severe damage of the other organs, including lung and adrenal.

Acidosis↗