Thesis--Rotterdam. / Includes bibliographical references.

Thesis (Ph. D.)--Johns Hopkins University, 1935. / Vita. Typescript (carbon copy). Includes bibliographical references (p. 12).

No description available.

The purpose of this study was to determine the substrate (malonate or acetate) used to elongate palmitic acid to stearic acid by Aspergillus niger.

No description available.

Results of previous research on whole-cell cultures of Penicillium chrysogenum have suggested that acetyl CoA, without being converted to malonyl CoA, supplies the two carbon units for the elongation of palmitic acid. The purpose of this study was to determine the mode of elongation of 1-t4C palmityl CoA by a 20,000 x g mitochondrial pellet from P. chrysogenum.Acetyl CoA or malonyl CoA was incubated with radioactivelylabeled palmityl CoA for 20 minutes. Avidin was added to some experimental reaction mixtures. The resulting fatty acids were saponified, extracted with hexane, methylated with diazomethane, and purified by thin layer chromatography. The methyl esters were separated and identified by gas-liquid chromatography. The radioactivity of each methyl ester was determined by liquid scintillation spectrometry.Elongation of palmityl CoA was observed in the presence of acetyl CoA, but not in the presence of malonyl CoA. The addition avidin produced a greater proportion of short-chained fatty acidsthe expense of palmitic acid, but did not decrease the percentage of long-chained fatty acids produced.A high proportion of label was recovered in the C18:3 fatty acid, linolenic acid. This suggested that two pathways of linolenic acid synthesis may be operating in this organism.Methods for detection and control of cancer encompass a large area of today's research. Recent use of granulomas as a model for such detection and control may be a promising field, especially for monitoring tumor antigens and immune responses. These granuloma systems are increasingly becoming vehicles in the study of tumor immunology. Although granulomas may be induced naturally by means of foreign bodies i.e. viral, fungal, or bacterial agents, new methods are being established to produce artificial granuloma systems. These systems include chemical or foreign body implantations followed by tumor vaccine challenges. The research presented here involved the use of a golf ball-induced granuloma for the purpose of establishment of a detection system for immune responses. The use of a golf ball-induced granuloma provided a closed system for monitoring cell-mediated and humoral responses to tumor antigens. Immune responses were monitored by means of hematocrits (packed blood cell counts), white blood cell differential counts, and electrophoretic results.Hematocrit results indicated no great immune response to the closed vaccine injected granulomasystems. Observations made on differential white blood cell counts indicated decreasing neutrophil/lymphocyte ratios for cellular immune responses. Electrophoretic results for granuloma fluids indicated decreases in albumin levels concurrent with increases in peak two,and complete loss of peak three following vaccination. Responses to tumor specific antigens in the form of cell-mediated immune responses are indicated by the results presented in this research. Utilization of the golf ball-induced granuloma system provided a means of separating the cell-mediated and humoral immune responses.Tumor specific antigens elicited various immune responses and provide hope for future identification of tumors by this method. Future development and utilization of the golf ball-induced granuloma system may be potential means of monitoring cell-mediated immune responses to tumor malignancies.

The relatively high level of palmitic acid (22 mol%) in cottonseeds may be due in part to the activity of a palmitoyl-acyl carrier protein (ACP) thioesterase (PATE). In embryo extracts, PATE activity was highest at the maximum rate of reserve accumulation (oil and protein). The cotton FatB mRNA transcript abundance also peaked during this developmental stage, paralleling the profiles of PATE enzyme activity and seed oil accumulation. A cotton FatB cDNA clone was isolated by screening a cDNA library with a heterologous Arabidopsis FatB probe (Pirtle et al., 1999, Plant and Cell Physiology 40: 155-163). The predicted amino acid sequence of the cotton PATE preprotein had 63% identity to the Arabidopsis FatB thioesterase sequence, suggesting that the cotton cDNA clone probably encoded a FatB-type thioesterase. When acyl-CoA synthetase-minus E. coli mutants expressed the cotton cDNA, an increase in 16:0 free fatty acid content was measured in the culture medium. In addition, acyl-ACP thioesterase activity assays in E. coli lysates revealed that there was a preference for palmitoyl-ACP over oleoyl-ACP in vitro, indicating that the cotton putative FatB cDNA encoded a functional thioesterase with a preference for saturated acyl-ACPs over unsaturated acyl-ACPs (FatA). Overexpression of the FatB cDNA in transgenic cotton resulted in elevated levels of palmitic acid in transgenic somatic embryos compared to control embryos. Expression of the anti-sense FatB cDNA in transgenic cotton plants produced some plants with a dwarf phenotype. These plants had significantly smaller mature leaves, all with smaller cells, suggesting that these plants may have less palmitic acid available for incorporation into extraplastidial membrane lipids during cell expansion. Thus manipulation of FatB expression in cotton directly influenced palmitic acid levels. Collectively, data presented in this dissertation support the hypothesis that there indeed is a palmitoyl-ACP thioesterase in cotton, encoded by the isolated FatB cDNA, which plays a major role in regulating palmitic acid content of extraplastidial complex glycerolipids. This work forms the basis for future studies of the influence of palmitic acid content on plant membrane function and provides a key target for the metabolic engineering of palmitic acid levels in storage oils of developing cottonseeds.

Os sais de lítio, sódio e potássio do ácido palmítico foram sintetizados a partir de meio aquoso e etanólico, usando os respectivos hidróxidos. Os sais foram caracterizados por análise elementar (AE) espectroscopia vibracional na região do infravermelho (IV), com claro deslocamento na banda de absorção da carbonila para menor número de onda quando se compara o ácido com os produtos das sínteses. O meio aquoso foi usado para prevenir uma eventual esterificação pelo álcool, catalisada pela base usada. Lavagem com carbonato de sódio também foi usada para eliminar excessos de ácido palmítico. O palmitato de etila também foi sintetizado e caracterizado por AE e IV, tendo sido constatada sua síntese. Tanto os sais quanto o éster foram submetidos a análise térmica por termogravimetria (TG) e análise térmica diferencial (DTA) entre temperatura ambiente e 900°C sob atmosfera dinâmica de ar, tendo sido observada a formação de carbonatos dos respectivos cátions, os quais foram caracterizados por IV. A calorimetria exploratória diferencial (DSC) foi realizada entre -90 °C e temperaturas próximas à decomposição das amostras, determinadas pelas curvas TG, em ciclos sucessivos de aquecimento e resfriamento. As curvas DSC mostraram claramente os pontos de fusão e conversões entre fases cristalinas tanto para os sais, como para o éster. Foi possível observar uma transição de fase, controversa na literatura, para o sal de sódio e observar eventos ainda não descritos para o éster, que pode ser usado na preparação de biodiesel, um combustível alternativo de grande interesse na atualidade. / Lithium, sodium and potassium salts of the palmitic acid were synthesized and characterized from aqueous and ethanolic medium, using the respective hydroxides. The salts were characterized by elemental analysis (EA) and infrared spectroscopy (IR), with clear displacement in the carbonyl absorption band to lower wave number when compared with that for the acid. Aqueous media was used in order to prevent an eventual esterification by the alcohol catalyzed by the base. Washing of the salt with sodium hydrogen carbonate solution removed the excess palmitic acid. EA and IR, being its synthesis comproved, also characterized the ethyl palmitate. All the salts and the ester were submitted to thermal analysis using thermogravimetry (TG), and differential thermal analysis (DTA) in the temperature ranging from room to 900 °C under air dynamic atmos phere. The respective carbonates were obtained as final degradation products according to IR. Differential scanning calorimetry (DSC) measurements were taken from –90 °C up to temperatures close to the starting of the decomposition temperature, determined by thermogravimetry, using heating and cooling cycles. The DSC curves presented melting and several phase transitions for both the salts and the ester. It was possible to observe a controversial event for the sodium salt as well as several events not described for the ester, which can be used in the preparation of the biodiesel, an alternative fuel with great interest nowadays.

Ph.D.

The aim of this thesis was to investigate how dietary fatty acids affect the risk for cardiometabolic disease, i.e. cardiovascular disease (CVD), type 2 diabetes and obesity. The overall hypothesis was that unsaturated fatty acids and especially the predominant polyunsaturated fatty acid (PUFA) linoleic acid (LA), 18:2n-6, would decrease cardiometabolic risk compared with saturated fatty acids (SFAs), in line with current recommendations to partly replace dietary SFA with PUFA. Papers I and V were observational studies based on the community-based cohort Uppsala Longitudinal Study of Adult Men (ULSAM). Adipose tissue fatty acid composition was determined as biomarker for dietary fat intake. Studies II, III and IV were randomised short-term interventions on human volunteers, in which different dietary fats were provided to the participants. In 71-year-old men, adipose tissue LA and α-linolenic acid (18:3n-3) were associated with insulin sensitivity (euglycaemic clamp), although this association was diminished for LA after adjusting for lifestyle variables. Different SFA displayed divergent associations; only palmitic acid (16:0) was inversely associated with insulin sensitivity (Paper I). In Cox regression analyses, LA was modestly associated with decreased all-cause mortality, but not CVD mortality during 15 years follow-up (Paper V). In a 3+3-week cross-over study on 20 weight-stable volunteers with dyslipidaemia, all foods were provided. A rapeseed oil-based diet distinctly lowered low-density lipoprotein cholesterol and triglycerides compared with a dairy-fat based diet (butter, cream and fatty cheese). Insulin sensitivity or coagulation factors were not affected (Paper II). In a 10-week randomised trial on 67 abdominally obese participants, PUFA (mostly sunflower oil) decreased liver fat compared with SFA (mostly butter) under isocaloric conditions. In individuals considered highly compliant to study diets, lipoproteins were also decreased during the PUFA diet (Paper III). In a 7-week double-blind randomised trial on 41 healthy volunteers, PUFA (sunflower oil) decreased the total:HDL cholesterol ratio compared with SFA (palm oil) during moderate weight gain (1.5 kg) (Paper IV). In conclusion, LA (PUFA) intake is associated with decreased cardiometabolic risk compared with higher SFA intake, overall supporting a beneficial role of non-tropical vegetable oils in place of solid fats in preventing fatty liver and cardiometabolic disorders.