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Biomedical subjects

A Wretlind

Publications and source records attributed to A Wretlind.

At least 19 recordsLinked to original sources
PubMed1998

[Total parenteral nutrition. History. Present time. Future].

Total parenteral nutrition (TPN) has been available for only 30 years. However, history in this field goes back more than 350 years with the first landmark being the description of general blood circulation by William Harvey in 1628. His discovery is the anatomical basis for intravenous infusions. Many investigations were performed during the following centuries showing that solutions containing electrolytes and glucose could be given intravenously in man. The accumulated knowledge of protein metabolism formed the basis for studies on intravenous nutrition with protein hydrolysates, peptides and amino acids. The observation in the late 30-s by Robert Elman that amino acids in the form of protein hydrolysate could be safely administered intravenously in man was the first major step toward TPN. During the following years, major efforts were made to find methods to prepare infusion solutions with a high energy content and low osmotic pressure. The most realistic alternative seemed to be fat in the form of an emulsion. Many studies of a large number of various fat emulsions were made however, all of these emulsions caused severe adverse reactions in man. The first safe fat emulsion, intralipid, was made available in the early 60s. This was the second major step toward TPN. It was then no problem to include vitamins, electrolytes and trace elements in the fat emulsions and the solutions of amino acids and glucose. A few years later it was shown that a central venous catheter could be used to administer the infusion fluid intravenously. Many clinical investigations and reports have shown that the newly developed intravenous nutritional regimens are adequate alternatives to the ordinary diet. In this way it has been possible to maintain or obtain a good nutritional condition in most situations when oral or tube feeding can not be used. TPN has been shown to be of very great clinical importance to prevent and treat starvation often related to high morbidity and mortality.

Forecasting↗
PubMed1994

Lipid mediated modification of rat heart allograft survival.

The effect on allograft survival of intravenous fat emulsions that differed in the ratio of functionally important n-3 and n-6 fatty acids was studied in a heterotopic cardiac transplant model in rats. Twenty percent fat emulsions were administered by continuous infusion at a dosage of 9 g fat/kg body weight per day, starting immediately after transplantation and continuing until complete rejection. The n-6 and n-3 fatty acids represent 75%, 43%, 60%, and 59% of all fatty acids in safflower oil, fish oil, soybean oil, and a 1:1 mixture of safflower and fish oil, respectively. The n-6 fatty acids predominate in safflower oil (370/1) and soybean oil (6.5/1), while the n-3 fatty acids dominate in the fish oil (7.6/1). The 1:1 mixture of safflower and fish oil has the balanced composition (n-6/n-3 = 2.1/1) recommended by Kinsella and served as oil-treated controls. Continuous infusion of safflower oil, fish oil, and soybean oil prolonged graft survival time to 13.3, 12.3, and 10.4 days, respectively, compared to 6.8 days in the oil-treated controls (P < 0.01 for all comparisons). Another control group infused with saline rejected the allografts after 7.8 days (P = NS compared to oil-treated controls; P < 0.01 for all other comparisons). The data suggest that intravenous administration of polyunsaturated fat emulsions results in an immunosuppressive effect that seems to be dependent on the n-3/n-6 fatty acid ratio of the fat emulsion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Recollections of pioneers in nutrition: landmarks in the development of parenteral nutrition.

Total parenteral nutrition (TPN) has been available for only 30 years. The successful development of this therapy, in a modern sense, was initiated in the late 30s. However, history in this field goes back more than 350 years, with the first landmark being the description of general blood circulation by William Harvey in 1628. His discovery is the anatomical basis for intravenous infusions. Many investigations were performed during the following centuries showing that solutions containing electrolytes and glucose could be given intravenously in man. The accumulated knowledge of protein metabolism formed the basis for studies on intravenous nutrition with protein hydrolysates, peptides and amino acids. The observation in the late 30s by Robert Elman that amino acids in the form of protein hydrolysate could be administered safely in man was the first major step toward TPN. During the following years, major efforts were made to find methods to prepare infusion solutions with a high energy content and low osmotic pressure. The most realistic alternative seemed to be fat in the form of an emulsion. Many studies of a large number of various fat emulsions were made from the 20s until the end of the 50s. However, all of these emulsions caused severe adverse reactions in man. The first safe fat emulsion, Intralipid, was made available in the early 60s. This was the second major step toward TPN. It was then no problem to include vitamins, electrolytes and trace elements in the fat emulsions and the solutions of amino acids and glucose.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1989

[Future perspectives in parenteral nutrition].

Some of the future perspectives of parenteral nutrition will most likely be related to the possibilities of improving the infusion solutions used. There are studies indicating that intravenous amino acid mixtures may produce better biochemical and clinical effects either by increasing the content of histidin, arginine, tyrosine, cysteine/cystine and branched chain amino acids or by adding glutamine, ornithin, ornithin-ketoglutaric acid, taurine and glutathion. Several possibilities of improving the intravenous fat emulsions have been studied and discussed. The use of medium chain fatty acid glycerides (MCT) instead of long chain fatty acid glycerides (LCT) may be of some value. Physical mixtures of LCT and MCT have been studied. Glycerides of both medium chain and long chain fatty acids of the same glycerol molecule ('structured lipids') have also been investigated. The omega-3-fatty acids (alfalinolenic, eicosapentaenoic and docosahexaenoic acid) have unique biochemical properties which may be beneficial in various clinical situations when parenteral nutrition is indicated. Intravenous fat emulsions containing triglycerides of these fatty acids are now being extensively investigated. The omega-3-fatty acids will change the pattern of eicosanoids formed, reduce the tendency to platelet aggregation, increase the resistance to endotoxins, and reduce the viscosity of the blood. Triglycerides of gamma linolenic acid have been considered to be of value in situations when there may be a reduced activity of delta-6-desaturase to transform linoleic acid to arachidonic acid. Many other known (carnitine, non-protein sources, vitamins and trace elements) or unknown nutrients may be found to be useful in order to improve the infusion solutions used in parenteral nutrition.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1987

The metabolic response to glycerol during parenteral nutrition.

The use of various nonprotein energy sources in parenteral nutrition regimens has been discussed for many years. Besides glucose, glycerol, xylitol, fructose and sorbitol are currently being used as water-soluble parenteral fuels. Despite the increasing frequency with which these glucose substitutes are being used, little information is available regarding the differences they evoke in host responses. All experimental evidence to date has shown glycerol to be equally effective in sparing body nitrogen as glucose when supplied in hypocaloric amounts. Results from studies in injured animals suggest that exogenously administered glycerol is a more potent inhibitor of fatty acid oxidation than glucose. Although results from human volunteers have been variable, glycerol administration after injury appears to markedly reduce fatty acid oxidation and ketogenesis, as well as increase hepatic glycogen. Glycerol toxicity appears to result only from its excessive administration, or when administered intraperitoneally or subcutaneously. Intravenous administration of hypocaloric quantities of glycerol alone or as a component of total parenteral nutrition is safe and effective.

Dose-Response Relationship, Drug↗
PubMed1987

New developments in lipid emulsions for parenteral nutrition.

More than one thousand publications have demonstrated the safety and efficacy of today's lipid emulsions including long chain fatty acids under experimental and clinical conditions. This has resulted in a general acceptance of a dual energy system comprising both carbohydrates and lipids as non-protein calories in total parenteral nutrition. Non-carnitine-dependent fatty acid has been suggested as a superior energy source in clinical situations where carnitine may be in the subnormal range. A medium chain triglyceride (MCT) emulsion would provide an energy source with a more readily oxidizable substrate. The tolerance of MCT is less than that of long chain triglyceride (LCT), whereby only physical mixtures of these emulsions will be used in humans. A structured lipid (SL) is a triglyceride which includes both medium and long chained fatty acids within the same triglyceride. Emulsions including SL have demonstrated a decreased protein energy expenditure and increased serum albumin in burned animal. The SL has also been superior to LCT emulsions in stimulating muscle protein synthesis and maintaining body weight in hepatectomized animals. These positive effects on protein kinetics have been concomitant with a lower RES involvement during septicemia in burned guinea pigs. Emulsions including fatty acids with odd-number carbons give a possibility to provide a fat emulsion which also could contribute positively to the glucose homeostasis. The omega-3 family of fatty acids has demonstrated a potential pharmacologic effect with regard to their ability to decrease blood viscosity and improve survival rate in endotoxin shock in an experimental model. These observations have been ascribed to changes in thromboxin A2 levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Fat Emulsions, Intravenous↗
PubMed1985

Nutrient requirements in various clinical conditions.

We now have a fairly good knowledge of the number of essential nutrients required in man. However, the studies are limited on the exact basic, minimal and optimal requirements of these nutrients in various conditions. Many more investigations are necessary in this field of clinical nutrition. We also need more information on the various biological and clinical parameters to be used in such studies. However, the present recommendations of the nutrient intakes in various clinical situations seem to be sufficient to maintain or obtain a good nutritional status in many clinical conditions and to prevent nutrient deficiency symptoms. Most of these recommendations are generous in relation to the basic requirements. The achievements in this field make us currently able to nourish our patients properly either by well-balanced ordinary hospital food or by tube feeding or parenteral nutrition.

Amino Acids↗
PubMed1982

Standards for nutritional adequacy of the diet: European and WHO/FAO viewpoints.

The dietary recommendations of FAO/WHO and of the various European nations differ in several ways. There are two types of dietary recommendations or standards. The first is related to the recommended daily intake of nutrient and the second refers to the nutrient content of the diet expressed either as percentage of total energy (energy % or cal %) derived from protein, fat, and carbohydrate or as the amounts of nutrients in relation to units of energy, the so-called nutrient concentration or nutrient density (weight per 1000 kcal, per 1 MJ or per 10 MJ). The numbers of recommended nutrients vary between eight and 28. The recommendations are given for individuals of different age, sex, and physiological status. The highest number of subgrouping is 41 and the lowest 11. The ranges of recommended values are sometimes very wide, but all seem acceptable from the nutritional point of view. There are many good reasons for this situation such as cultural background, food tradition, food production, and availability.

Adolescent↗
PubMed1978

Parenteral nutrition.

Parenteral nutrition therapy was born 35 to 40 years ago when the first steps were taken to perform a protein nutrition by the intravenous supply of amino acids in man. Since that time, many efforts have been made to supply adequate amounts of energy intravenously. These efforts have resulted in the two available systems for parenteral nutrition: the lipid-carbohydrate system and the glucose system. The lipid-carbohydrate system, which corresponds to the nutrient content of normal food, may be given either in a peripheral vein or through a central vein catheter. The glucose system is administered through a central venous catheter. Many problems concerning the parenteral nutrition need to be solved and further elucidated. However, our present knowledge and technique in this field are far advanced over earlier methods. Now all patients who cannot take food in adequate amounts orally or enterally may be kept in good nutritional status by parenteral nutrition. In this way it is possible to prevent starvation and its complications in these patients.

Adult↗
PubMed1978

[General aspects of intravenous feeding of cancer patients].

In order to obtain or maintain a good nutritional status in cancer patients, it is often necessary to perform intravenous nutrition. In summary, several studies have indicated that intravenous nutrition may be beneficial in association with surgery, radiation, or chemotherapy in patients with cancer. More controlled studies, however, are required. There is no indication at the present time of any adverse effects of this method of treatment in relation to tumor growth. The general nutritional improvement in patients on intravenous nutrition increases the immunocompetence, resistance to radiation and cytostatics as well as the mood and quality of life of the cancer patients. In very broad terms this new intravenous nutrition therapy means that a cancer patient should not be left without specific cancer therapy because of starvation and its serious or even fatal complications.

Acidosis↗
PubMed1978

[General aspects concerning the intravenous feeding of cancer patients].

In order to obtain or maintain a good nutritional status in cancer patients, it is often necessary to perform intravenous nutrition. In summary, several studies have indicated that intravenous nutrition may be beneficial in association with surgery, radiation, or chemotherapy in patients with cancer. More controlled studies, however, are required. There is no indication at the present time of any adverse effects of this method of treatment in relation to tumor growth. The general nutritional improvement in patients on intravenous nutrition increases the immunocompetence, resistance to radiation and cytostatic as well as the mood and quality of life of the cancer patients. In very broad terms this new intravenous nutrition therapy means that a cancer patient should not be left without specific cancer therapy because of starvation and its serious or even fatal complications.

Acidosis↗