Liver fat in the metabolic syndrome and type 2 diabetes

Introduction: The epidemic of obesity has been accompanied by an increase in the prevalence of the metabolic syndrome, type 2 diabetes, and non-alcoholic fatty liver disease (NAFLD). However, not all obese subjects develop these metabolic abnormalities. Hepatic fat accumulation is related to hepatic insulin resistance, which in turn leads to hyperglycemia, hypertriglyceridemia, and a low HDL cholesterol con-centration. The present studies aimed to investigate 1) how intrahepatic as compared to intramyocellular fat is related to insulin resistance in these tissues and to the metabolic syndrome (Study I); 2) the amount of liver fat in subjects with and without the metabolic syndrome, and which clinically available markers best reflect liver fat content (Study II); 3) the effect of liver fat on insulin clearance (Study III); 4) whether type 2 diabetic patients have more liver fat than age-, gender-, and BMI-matched non-diabetic subjects (Study IV); 5) how type 2 diabetic patients using exceptionally high doses of insulin respond to addition of a PPARγ agonist (Study V). Subjects and methods: The study groups consisted of 45 (Study I), 271 (Study II), and 80 (Study III) non-diabetic subjects, and of 70 type 2 diabetic patients and 70 matched control subjects (Study IV). In Study V, a total of 14 poorly controlled type 2 diabetic patients treated with high doses of insulin were studied before and after rosiglitazone treatment (8 mg/day) for 8 months. In all studies, liver fat content was measured by proton magnetic resonance spectroscopy, and sub-cutaneous and intra-abdominal fat content by MRI. In addition, circulating markers of insulin resistance and serum liver enzyme concentrations were determined. Hepatic (i.v. insulin infusion rate 0.3 mU/kg∙min combined with [3-3H]glucose, Studies I, III, and V) and muscle (1.0 mU/kg min, Study I) insulin sensitivities were measured by the euglycemic hyperinsulinemic clamp technique. Results: Fat accumulation in the liver rather than in skeletal muscle was associated with features of insulin resistance, i.e. increased fasting serum (fS) triglycerides and decreased fS-HDL cholesterol, and with hyperinsulinemia and low adiponectin concentrations (Study I). Liver fat content was 4-fold higher in subjects with as compared to those without the metabolic syndrome, independent of age, gender, and BMI. FS-C-peptide was the best correlate of liver fat (Study II). Increased liver fat was associated with both impaired insulin clearance and hepatic insulin resistance independent of age, gender, and BMI (Study III). Type 2 diabetic patients had 80% more liver fat than age-, weight-, and gender-matched non-diabetic subjects. At any given liver fat content, S-ALT underestimated liver fat in the type 2 diabetic patients as compared to the non-diabetic subjects (Study IV). In Study V, hepatic insulin sensitivity increased and glycemic control improved significantly during rosiglitazone treatment. This was associated with lowering of liver fat (on the average by 46%) and insulin requirements (40%). Conclusions: Liver fat is increased both in the metabolic syndrome and type 2 diabetes independent of age, gender, and BMI. A fatty liver is associated with both hepatic insulin resistance and impaired insulin clearance. Rosi-glitazone may be particularly effective in type 2 diabetic patients who are poorly controlled despite using high insulin doses.

Adipose tissue inflammation, liver fat and insulin resistance in humans

BACKGROUND: Obesity is closely associated with insulin resistance, which is a pathophysiologic condition contributing to the important co-morbidities of obesity, such as the metabolic syndrome and type 2 diabetes mellitus. In obese subjects, adipose tissue is characterized by inflammation (macrophage infiltration, increased expression insulin resistance genes and decreased expression of insulin sensitivity genes). Increased liver fat, without excessive alcohol consumption, is defined as non-alcoholic fatty liver disease (NAFLD) and also associated with obesity and insulin resistance. It is unknown whether and how insulin resistance is associated with altered expression of adipocytokines (adipose tissue-derived signaling molecules), and whether adipose tissue inflammation and NAFLD coexist independent of obesity. Genetic factors could explain variation in liver fat independent of obesity but the heritability of NAFLD is unknown. AIMS: To determine whether acute regulation of adipocytokine expression by insulin in adipose tissue is altered in obesity. To investigate the relationship between adipose tissue inflammation and liver fat content independent of obesity. To assess the heritability of serum alanine aminotransferase (ALT) activity, a surrogate marker of liver fat. METHODS: 55 healthy normal-weight and obese volunteers were recruited. Subcutaneous adipose tissue biopsies were obtained for measurement of gene expression before and during 6 hours of euglycemic hyperinsulinemia. Liver fat content was measured by proton magnetic resonance spectroscopy, and adipose tissue inflammation was assessed by gene expression, immunohistochemistry and lipidomics analysis. Genetic factors contributing to serum ALT activity were determined in 313 twins by statistical heritability modeling. RESULTS: During insulin infusion the expression of insulin sensitivity genes remains unchanged, while the expression of insulin resistance genes increases in obese/insulin-resistant subjects compared to insulin-sensitive subjects. Adipose tissue inflammation is associated with liver fat content independent of obesity. Adipose tissue of subjects with high liver fat content is characterized infiltrated macrophages and increased expression of inflammatory genes, as well as by increased concentrations of ceramides compared to equally obese subjects with normal liver fat. A significant heritability for serum ALT activity was verified. CONCLUSIONS: Effects of insulin infusion on adipose tissue gene expression in obese/insulin-resistant subjects are not only characterized by hyporesponse of insulin sensitivity genes but also by hyperresponse of insulin resistance and inflammatory genes. This suggests that in obesity, the impaired insulin action contributes or self-perpetuates alterations in adipocytokine expression in adipose tissue. Adipose tissue inflammation is increased in subjects with high liver fat compared to equally obese subjects with normal liver fat content. Concentrations of ceramides, the putative mediators of insulin resistance, are increased in adipose tissue in subjects with high liver fat. Genetic factors contribute significantly to variation in serum ALT activity, a surrogate marker of liver fat. These data imply that adipose tissue inflammation and increased liver fat content are closely interrelated, and determine insulin resistance even independent of obesity.

Quantitative trait loci detection and benefits from marker-assisted selection in dairy cattle

Knowing the chromosomal areas or actual genes affecting the traits under selection would add more information to be used in the selection decisions which would potentially lead to higher genetic response. The first objective of this study was to map quantitative trait loci (QTL) affecting economically important traits in the Finnish Ayrshire population. The second objective was to investigate the effects of using QTL information in marker-assisted selection (MAS) on the genetic response and the linkage disequilibrium between the different parts of the genome. Whole genome scans were carried out on a grand-daughter design with 12 half-sib families and a total of 493 sons. Twelve different traits were studied: milk yield, protein yield, protein content, fat yield, fat content, somatic cell score (SCS), mastitis treatments, other veterinary treatments, days open, fertility treatments, non-return rate, and calf mortality. The average spacing of the typed markers was 20 cM with 2 to 14 markers per chromosome. Associations between markers and traits were analyzed with multiple marker regression. Significance was determined by permutation and genome-wise P-values obtained by Bonferroni correction. The benefits from MAS were investigated by simulation: a conventional progeny testing scheme was compared to a scheme where QTL information was used within families to select among full-sibs in the male path. Two QTL on different chromosomes were modelled. The effects of different starting frequencies of the favourable alleles and different size of the QTL effects were evaluated. A large number of QTL, 48 in total, were detected at 5% or higher chromosome-wise significance. QTL for milk production were found on 8 chromosomes, for SCS on 6, for mastitis treatments on 1, for other veterinary treatments on 5, for days open on 7, for fertility treatments on 7, for calf mortality on 6, and for non-return rate on 2 chromosomes. In the simulation study the total genetic response was faster with MAS than with conventional selection and the advantage of MAS persisted over the studied generations. The rate of response and the difference between the selection schemes reflected clearly the changes in allele frequencies of the favourable QTL. The disequilibrium between the polygenes and QTL was always negative and it was larger with larger QTL size. The disequilibrium between the two QTL was larger with QTL of large effect and it was somewhat larger with MAS for scenarios with starting frequencies below 0.5 for QTL of moderate size and below 0.3 for large QTL. In conclusion, several QTL affecting economically important traits of dairy cattle were detected. Further studies are needed to verify these QTL, check their presence in the present breeding population, look for pleiotropy and fine map the most interesting QTL regions. The results of the simulation studies show that using MAS together with embryo transfer to pre-select young bulls within families is a useful approach to increase the genetic merit of the AI-bulls compared to conventional selection.

Spectroscopy of tissue triglyceride composition : In vitro and in vivo studies

Lipid analysis is commonly performed by gas chromatography (GC) in laboratory conditions. Spectroscopic techniques, however, are non-destructive and can be implemented noninvasively in vivo. Excess fat (triglycerides) in visceral adipose tissue and liver is known predispose to metabolic abnormalities, collectively known as the metabolic syndrome. Insulin resistance is the likely cause with diets high in saturated fat known to impair insulin sensitivity. Tissue triglyceride composition has been used as marker of dietary intake but it can also be influenced by tissue specific handling of fatty acids. Recent studies have shown that adipocyte insulin sensitivity correlates positively with their saturated fat content, contradicting the common view of dietary effects. A better understanding of factors affecting tissue triglyceride composition is needed to provide further insights into tissue function in lipid metabolism. In this thesis two spectroscopic techniques were developed for in vitro and in vivo analysis of tissue triglyceride composition. In vitro studies (Study I) used infrared spectroscopy (FTIR), a fast and cost effective analytical technique well suited for multivariate analysis. Infrared spectra are characterized by peak overlap leading to poorly resolved absorbances and limited analytical performance. In vivo studies (Studies II, III and IV) used proton magnetic resonance spectroscopy (1H-MRS), an established non-invasive clinical method for measuring metabolites in vivo. 1H-MRS has been limited in its ability to analyze triglyceride composition due to poorly resolved resonances. Using an attenuated total reflection accessory, we were able to obtain pure triglyceride infrared spectra from adipose tissue biopsies. Using multivariate curve resolution (MCR), we were able to resolve the overlapping double bond absorbances of monounsaturated fat and polyunsaturated fat. MCR also resolved the isolated trans double bond and conjugated linoleic acids from an overlapping background absorbance. Using oil phantoms to study the effects of different fatty acid compositions on the echo time behaviour of triglycerides, it was concluded that the use of long echo times improved peak separation with T2 weighting having a negligible impact. It was also discovered that the echo time behaviour of the methyl resonance of omega-3 fats differed from other fats due to characteristic J-coupling. This novel insight could be used to detect omega-3 fats in human adipose tissue in vivo at very long echo times (TE = 470 and 540 ms). A comparison of 1H-MRS of adipose tissue in vivo and GC of adipose tissue biopsies in humans showed that long TE spectra resulted in improved peak fitting and better correlations with GC data. The study also showed that calculation of fatty acid fractions from 1H-MRS data is unreliable and should not be used. Omega-3 fatty acid content derived from long TE in vivo spectra (TE = 540 ms) correlated with total omega-3 fatty acid concentration measured by GC. The long TE protocol used for adipose tissue studies was subsequently extended to the analysis of liver fat composition. Respiratory triggering and long TE resulted in spectra with the olefinic and tissue water resonances resolved. Conversion of the derived unsaturation to double bond content per fatty acid showed that the results were in accordance with previously published gas chromatography data on liver fat composition. In patients with metabolic syndrome, liver fat was found to be more saturated than subcutaneous or visceral adipose tissue. The higher saturation observed in liver fat may be a result of a higher rate of de-novo-lipogenesis in liver than in adipose tissue. This thesis has introduced the first non-invasive method for determining adipose tissue omega-3 fatty acid content in humans in vivo. The methods introduced here have also shown that liver fat is more saturated than adipose tissue fat.

Spectroscopy of tissue triglyceride composition : In vitro and in vivo studies

Lipid analysis is commonly performed by gas chromatography (GC) in laboratory conditions. Spectroscopic techniques, however, are non-destructive and can be implemented noninvasively in vivo. Excess fat (triglycerides) in visceral adipose tissue and liver is known predispose to metabolic abnormalities, collectively known as the metabolic syndrome. Insulin resistance is the likely cause with diets high in saturated fat known to impair insulin sensitivity. Tissue triglyceride composition has been used as marker of dietary intake but it can also be influenced by tissue specific handling of fatty acids. Recent studies have shown that adipocyte insulin sensitivity correlates positively with their saturated fat content, contradicting the common view of dietary effects. A better understanding of factors affecting tissue triglyceride composition is needed to provide further insights into tissue function in lipid metabolism. In this thesis two spectroscopic techniques were developed for in vitro and in vivo analysis of tissue triglyceride composition. In vitro studies (Study I) used infrared spectroscopy (FTIR), a fast and cost effective analytical technique well suited for multivariate analysis. Infrared spectra are characterized by peak overlap leading to poorly resolved absorbances and limited analytical performance. In vivo studies (Studies II, III and IV) used proton magnetic resonance spectroscopy (1H-MRS), an established non-invasive clinical method for measuring metabolites in vivo. 1H-MRS has been limited in its ability to analyze triglyceride composition due to poorly resolved resonances. Using an attenuated total reflection accessory, we were able to obtain pure triglyceride infrared spectra from adipose tissue biopsies. Using multivariate curve resolution (MCR), we were able to resolve the overlapping double bond absorbances of monounsaturated fat and polyunsaturated fat. MCR also resolved the isolated trans double bond and conjugated linoleic acids from an overlapping background absorbance. Using oil phantoms to study the effects of different fatty acid compositions on the echo time behaviour of triglycerides, it was concluded that the use of long echo times improved peak separation with T2 weighting having a negligible impact. It was also discovered that the echo time behaviour of the methyl resonance of omega-3 fats differed from other fats due to characteristic J-coupling. This novel insight could be used to detect omega-3 fats in human adipose tissue in vivo at very long echo times (TE = 470 and 540 ms). A comparison of 1H-MRS of adipose tissue in vivo and GC of adipose tissue biopsies in humans showed that long TE spectra resulted in improved peak fitting and better correlations with GC data. The study also showed that calculation of fatty acid fractions from 1H-MRS data is unreliable and should not be used. Omega-3 fatty acid content derived from long TE in vivo spectra (TE = 540 ms) correlated with total omega-3 fatty acid concentration measured by GC. The long TE protocol used for adipose tissue studies was subsequently extended to the analysis of liver fat composition. Respiratory triggering and long TE resulted in spectra with the olefinic and tissue water resonances resolved. Conversion of the derived unsaturation to double bond content per fatty acid showed that the results were in accordance with previously published gas chromatography data on liver fat composition. In patients with metabolic syndrome, liver fat was found to be more saturated than subcutaneous or visceral adipose tissue. The higher saturation observed in liver fat may be a result of a higher rate of de-novo-lipogenesis in liver than in adipose tissue. This thesis has introduced the first non-invasive method for determining adipose tissue omega-3 fatty acid content in humans in vivo. The methods introduced here have also shown that liver fat is more saturated than adipose tissue fat.

Aitosuklaa jäätelöpuikon kuorrutteena

Tutkimuksen kirjallisuuskatsauksessa keskityttiin jäätelöpuikkoihin, erilaisiin suklaakuorrutteisiin ja elintarvikkeiden kuorruttamiseen suklaalla. Lisäksi kirjallisuuskatsauksessa perehdyttiin suklaan koostumukseen, nestemäisen suklaan virtausominaisuuksiin ja koostumuksen ja virtausominaisuuksien välisiin vuorovaikutuksiin. Kokeellisessa osassa tavoitteena oli selvittää, miten maitosuklaakuorrutteen rasvapitoisuuden, emulgointiainepitoisuuden ja kuorrutteen lämpötilanvaihtelut vaikuttavat kuorrutteen viskositeettiin, myötöjännitykseen, jähmettymisaikaan ja jäätelöpuikon päälle jäävän kuorrutteen määrään. Erityisesti pyrittiin selvittämään, miten jäätelöpuikon päälle jäävän kuorrutteen määrää saadaan säädeltyä kuorrutteen rasvapitoisuutta, emulgointiainepitoisuutta ja lämpötilaa muuttamalla. Tutkimuksen koeasetelma tehtiin Box-Behnken-mallilla. Selittäviksi muuttujiksi tutkimukseen valittiin kuorrutteen rasvan määrä, emulgointiaineen määrä ja kuorrutteen lämpötila jäätelöpuikkoja kuorrutettaessa. Vastemuuttujina oli kuorrutteen jähmettymisaika, viskositeetti, myötöjännitys ja jäätelöpuikon päälle jäävän kuorrutteen määrä. Tulokset käsiteltiin regressioanalyysin avulla. Muuttujien välisiä vuorovaikutuksia tutkittiin vastepintamallilla. Vastemuuttujien välisiä korrelaatioita tutkittaessa käytettiin Pearsonin korrelaatiokerrointa. Kuorrutteen rasvan määrän lisääntyminen vähensi tilastollisesti merkitsevästi jäätelöpuikon päälle jäävän kuorrutteen määrää, kuorrutteen jähmettymisaikaa, viskositeettia ja myötöjännitystä. Emulgointiaineen määrän lisääminen kuorrutteessa pienensi kuorrutteen määrää jäätelöpuikon päällä, kuorrutteen jähmettymisaikaa ja kuorrutteen myötöjännitystä. Kuorrutteen lämpötilan lisääminen jäätelöpuikkoja kuorrutettaessa pienensi kuorrutteen määrää ja viskositeettia. Kuorrutteen jähmettymisaika sen sijaan piteni lämpötilaa lisättäessä. Tutkimuksen perusteella voidaan sanoa, että jäätelöpuikkoja kastettaessa suklaakuorrutteen lämpötila, rasvan määrä ja lesitiinin määrä vaikuttivat jäätelöpuikon päälle jäävän kuorrutteen määrään. Vastepintamallinnuksen käyttö soveltui hyvin suklaakuorrutteen määrän tutkimiseen. Sen avulla saatiin selvitettyä, miten jäätelöpuikon päälle jäävän kuorrutteen määrää saadaan säädeltyä muuttamalla kuorrutteen emulgointiainepitoisuutta, rasvapitoisuutta ja lämpötilaa.

Konjac- ja galaktoglukomannaanipohjaiset emulsiokalvot

Emulsiokalvolla tarkoitetaan kalvoa, joka on valmistettu haihduttamalla ylimääräinen vesi pois emulsiosta. Polysakkaridipohjainen emulsiokalvo koostuu kalvonmuodostuspolysakkaridista, rasvasta, emulgointiaineesta ja pehmittimestä. Kirjallisuusosassa selvitettiin, mitä raaka-aineita polysakkaridipohjaisissa emulsiokalvoissa käytetään ja mitkä tekijät vaikuttavat emulsiokalvojen vesihöyrynläpäisevyyteen ja mekaanisiin ominaisuuksiin. Tutkimuksen kokeellisen osan tavoitteena oli selvittää, miten konjac-glukomannaani (KGM) ja kuusen galaktoglukomannaani (GGM) soveltuvat emulsiokalvon raaka-aineiksi. Lisäksi selvitettiin, miten rasvan tyyppi ja rasvapitoisuus vaikuttavat GGM-KGM-pohjaisten emulsiokalvojen mekaanisiin ominaisuuksiin ja vesihöyrynläpäisevyyteen. Mehiläisvahasta, mäntyöljystä ja rypsiöljystä valmistettiin emulsiokalvot, joissa oli 30 %:n (paino-% GGM:sta) rasvapitoisuudet. Lisäksi mehiläisvahasta valmistettiin emulsiokalvot, joissa oli 10 ja 50 % mehiläisvahaa. Emulsiokalvoja verrattiin vertailukalvoon, jossa ei ollut rasvaa. Kalvoissa käytetty KGM:n ja GGM:n suhde oli 1:1. Kalvoista mitattiin vesihöyrynläpäisevyys ja -läpäisynopeus, vetolujuus, Youngin moduuli ja murtovenymä. Näiden lisäksi kalvojen poikkileikkaus kuvattiin pyyhkäisyelektronimikroskoopilla. GGM ja KGM soveltuvat emulsiokalvon raaka-aineiksi. Huoneenlämpötilassa kuivatuista kalvoista saatiin tasaisemman näköisiä kuin lämpökaapissa kuivatuista. Pyyhkäisyelektronimikroskooppikuvissa vahapisarat olivat öljypisaroita pienempiä, mikä mahdollisesti vaikutti siihen, että vahapisarat pysyivät paremmin kiinnittyneenä kalvomatriisissa. Öljypisaroiden koko oli kalvoissa noin 10 ?m ja vahapisaroiden 2–6 ?m. Vesihöyrynläpäisynopeus oli pienin 50 %:n mehiläisvahakalvolla (p < 0,05). Vesihöyrynläpäisevyys laski lineaarisesti mehiläisvahapitoisuuden suurentuessa. Öljykalvot ja 10 %:n mehiläisvahakalvo eivät eronneet tilastollisesti merkitsevästi vesihöyrynläpäisevyyden suhteen vertailukalvosta. Pienin vetolujuus ja Youngin moduuli oli 50 %:n mehiläisvahakalvolla. Vertailukalvo oli kestävin ja jäykin. Murtovenymän suhteen kalvot eivät eronneet toisistaan tilastollisesti merkitsevästi. Tutkimuksessa onnistuttiin valmistamaan GGM-KGM-pohjaisia emulsiokalvoja, jotka pidättivät vesihöyryä vertailukalvoa paremmin ja silti säilyttivät mekaaniset ominaisuutensa kohtuullisen hyvin.

Combination antiretroviral therapy -associated lipodystrophy : insights into pathogenesis and treatment

Introduction: Combination antiretroviral therapy (cART) has decreased morbidity and mortality of individuals infected with human immunodeficiency virus type 1 (HIV-1). Its use, however, is associated with adverse effects which increase the patients risk of conditions such as diabetes and coronary heart disease. Perhaps the most stigmatizing side effect is lipodystrophy, i.e., the loss of subcutaneous adipose tissue (SAT) in the face, limbs and trunk while fat accumulates intra-abdominally and dorsocervically. The pathogenesis of cART-associated lipodystrophy is obscure. Nucleoside reverse transcriptase inhibitors (NRTI) have been implicated to cause lipoatrophy via mitochondrial toxicity. There is no known effective treatment for cART-associated lipodystrophy during unchanged antiretroviral regimen in humans, but in vitro data have shown uridine to abrogate NRTI-induced toxicity in adipocytes. Aims: To investigate whether i) cART or lipodystrophy associated with its use affect arterial stiffness; ii) lipoatrophic SAT is inflamed compared to non-lipoatrophic SAT; iii) abdominal SAT from patients with compared to those without cART-associated lipoatrophy differs with respect to mitochondrial DNA (mtDNA) content, adipose tissue inflammation and gene expression, and if NRTIs stavudine and zidovudine are associated with different degree of changes; iv) lipoatrophic abdominal SAT differs from preserved dorsocervical SAT with respect to mtDNA content, adipose tissue inflammation and gene expression in patients with cART-associated lipodystrophy and v) whether uridine can revert lipoatrophy and the associated metabolic disturbances in patients on stavudine or zidovudine based cART. Subjects and methods: 64 cART-treated patients with (n=45) and without lipodystrophy/-atrophy (n=19) were compared cross-sectionally. A marker of arterial stiffness, heart rate corrected augmentation index (AgIHR), was measured by pulse wave analysis. Body composition was measured by magnetic resonance imaging and dual-energy X-ray absorptiometry, and liver fat content by proton magnetic resonance spectroscopy. Gene expression and mtDNA content in SAT were assessed by real-time polymerase chain reaction and microarray. Adipose tissue composition and inflammation were assessed by histology and immunohistochemistry. Dorsocervical and abdominal SAT were studied. The efficacy and safety of uridine for the treatment of cART-associated lipoatrophy were evaluated in a randomized, double-blind, placebo-controlled 3-month trial in 20 lipoatrophic cART-treated patients. Results: Duration of antiretroviral treatment and cumulative exposure to NRTIs and protease inhibitors, but not the presence of cART-associated lipodystrophy, predicted AgIHR independent of age and blood pressure. Gene expression of inflammatory markers was increased in SAT of lipodystrophic as compared to non-lipodystrophic patients. Expression of genes involved in adipogenesis, triglyceride synthesis and glucose disposal was lower and of those involved in mitochondrial biogenesis, apoptosis and oxidative stress higher in SAT of patients with than without cART-associated lipoatrophy. Most changes were more pronounced in stavudine-treated than in zidovudine-treated individuals. Lipoatrophic SAT had lower mtDNA than SAT of non-lipoatrophic patients. Expression of inflammatory genes was lower in dorsocervical than in abdominal SAT. Neither depot had characteristics of brown adipose tissue. Despite being spared from lipoatrophy, dorsocervical SAT of lipodystrophic patients had lower mtDNA than the phenotypically similar corresponding depot of non-lipodystrophic patients. The greatest difference in gene expression between dorsocervical and abdominal SAT, irrespective of lipodystrophy status, was in expression of homeobox genes that regulate transcription and regionalization of organs during embryonal development. Uridine increased limb fat and its proportion of total fat, but had no effect on liver fat content and markers of insulin resistance. Conclusions: Long-term cART is associated with increased arterial stiffness and, thus, with higher cardiovascular risk. Lipoatrophic abdominal SAT is characterized by inflammation, apoptosis and mtDNA depletion. As mtDNA is depleted even in non-lipoatrophic dorsocervical SAT, lipoatrophy is unlikely to be caused directly by mtDNA depletion. Preserved dorsocervical SAT of patients with cART-associated lipodystrophy is less inflamed than their lipoatrophic abdominal SAT, and does not resemble brown adipose tissue. The greatest difference in gene expression between dorsocervical and abdominal SAT is in expression of transcriptional regulators, homeobox genes, which might explain the differential susceptibility of these adipose tissue depots to cART-induced toxicity. Uridine is able to increase peripheral SAT in lipoatrophic patients during unchanged cART.

Understanding solid-state transformations during dehydration: new insights using vibrational spectroscopy and multivariate modelling

Many active pharmaceutical ingredients (APIs) have both anhydrate and hydrate forms. Due to the different physicochemical properties of solid forms, the changes in solid-state may result in therapeutic, pharmaceutical, legal and commercial problems. In order to obtain good solid dosage form quality and performance, there is a constant need to understand and control these phase transitions during manufacturing and storage. Thus it is important to detect and also quantify the possible transitions between the different forms. In recent years, vibrational spectroscopy has become an increasingly popular tool to characterise the solid-state forms and their phase transitions. It offers several advantages over other characterisation techniques including an ability to obtain molecular level information, minimal sample preparation, and the possibility of monitoring changes non-destructively in-line. Dehydration is the phase transition of hydrates which is frequently encountered during the dosage form production and storage. The aim of the present thesis was to investigate the dehydration behaviour of diverse pharmaceutical hydrates by near infrared (NIR), Raman and terahertz pulsed spectroscopic (TPS) monitoring together with multivariate data analysis. The goal was to reveal new perspectives for investigation of the dehydration at the molecular level. Solid-state transformations were monitored during dehydration of diverse hydrates on hot-stage. The results obtained from qualitative experiments were used to develop a method and perform the quantification of the solid-state forms during process induced dehydration in a fluidised bed dryer. Both in situ and in-line process monitoring and quantification was performed. This thesis demonstrated the utility of vibrational spectroscopy techniques and multivariate modelling to monitor and investigate dehydration behaviour in situ and during fluidised bed drying. All three spectroscopic methods proved complementary in the study of dehydration. NIR spectroscopy models could quantify the solid-state forms in the binary system, but were unable to quantify all the forms in the quaternary system. Raman spectroscopy models on the other hand could quantify all four solid-state forms that appeared upon isothermal dehydration. The speed of spectroscopic methods makes them applicable for monitoring dehydration and the quantification of multiple forms was performed during phase transition. Thus the solid-state structure information at the molecular level was directly obtained. TPS detected the intermolecular phonon modes and Raman spectroscopy detected mostly the changes in intramolecular vibrations. Both techniques revealed information about the crystal structure changes. NIR spectroscopy, on the other hand was more sensitive to water content and hydrogen bonding environment of water molecules. This study provides a basis for real time process monitoring using vibrational spectroscopy during pharmaceutical manufacturing.

Glycoalkaloid Content and Starch Structure in Solanum Species and Interspecific Somatic Potato Hybrids

When genome sections of wild Solanum species are bred into the cultivated potato (S. tuberosum L.) to obtain improved potato cultivars, the new cultivars must be evaluated for their beneficial and undesirable traits. Glycoalkaloids present in Solanum species are known for their toxic as well as for beneficial effects on mammals. On the other hand, glycoalkaloids in potato leaves provide natural protection against pests. Due to breeding, glycoalkaloid profile of the plant is affected. In addition, the starch properties in potato tubers can be affected as a result of breeding, because the crystalline properties are determined by the botanical source of the starch. Starch content and composition affect the texture of cooked and processed potatoes. In order to determine glycoalkaloid contents in Solanum species, simultaneous separation of glycoalkaloids and aglycones using reversed-phase high-performance liquid chromatography (HPLC) was developed. Clean-up of foliage samples was improved using a silica-based strong cation exchanger instead of octadecyl phases in solid-phase extraction. Glycoalkaloids alpha-solanine and alpha-chaconine were detected in potato tubers of cvs. Satu and Sini. The total glycoalkaloid concentration of non-peeled and immature tubers was at an acceptable level (under 20 mg/100 g of FW) in the cv. Satu, whereas concentration in cv. Sini was 23 mg/100 g FW. Solanum species (S. tuberosum, S. brevidens, S. acaule, and S. commersonii) and interspecific somatic hybrids (brd + tbr, acl + tbr, cmm + tbr) were analyzed for their glycoalkaloid contents using liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS). The concentrations in the tubers of the brd + tbr and acl + tbr hybrids remained under 20 mg/100 g FW. Glycoalkaloid concentration in the foliage of the Solanum species was between 110 mg and 890 mg/100 g FW. However, the concentration in the foliage of S. acaule was as low as 26 mg/100 g FW. The total concentrations of brd + tbr, acl + tbr, and cmm + tbr hybrid foliages were 88 mg, 180 mg, and 685 mg/100 g FW, respectively. Glycoalkaloids of both parental plants as well as new combinations of aglycones and saccharides were detected in somatic hybrids. The hybrids contained mainly spirosolanes, and glycoalkaloid structures having no 5,6-double bond in the aglycone. Based on these results, the glycoalkaloid profiles of the hybrids may represent a safer and more beneficial spectrum of glycoalkaloids than that found in currently cultivated varieties. Starch nanostructure of three different cultivars (Satu, Saturna, and Lady Rosetta), a wild species S. acaule, and interspecific somatic hybrids were examined by wide-angle and small-angle X-ray scattering (WAXS, SAXS). For the first time, the measurements were conducted on fresh potato tuber samples. Crystallinity of starch, average crystallite size, and lamellar distance were determined from the X-ray patterns. No differences in the starch nanostructure between the three different cultivars were detected. However, tuber immaturity was detected by X-ray scattering methods when large numbers of immature and mature samples were measured and the results were compared. The present study shows that no significant changes occurred in the nanostructures of starches resulting from hybridizations of potato cultivars.

From Polymorph Screening to Dissolution Testing - Solid Phase Analysis during Pharmaceutical Development and Manufacturing

Solid materials can exist in different physical structures without a change in chemical composition. This phenomenon, known as polymorphism, has several implications on pharmaceutical development and manufacturing. Various solid forms of a drug can possess different physical and chemical properties, which may affect processing characteristics and stability, as well as the performance of a drug in the human body. Therefore, knowledge and control of the solid forms is fundamental to maintain safety and high quality of pharmaceuticals. During manufacture, harsh conditions can give rise to unexpected solid phase transformations and therefore change the behavior of the drug. Traditionally, pharmaceutical production has relied on time-consuming off-line analysis of production batches and finished products. This has led to poor understanding of processes and drug products. Therefore, new powerful methods that enable real time monitoring of pharmaceuticals during manufacturing processes are greatly needed. The aim of this thesis was to apply spectroscopic techniques to solid phase analysis within different stages of drug development and manufacturing, and thus, provide a molecular level insight into the behavior of active pharmaceutical ingredients (APIs) during processing. Applications to polymorph screening and different unit operations were developed and studied. A new approach to dissolution testing, which involves simultaneous measurement of drug concentration in the dissolution medium and in-situ solid phase analysis of the dissolving sample, was introduced and studied. Solid phase analysis was successfully performed during different stages, enabling a molecular level insight into the occurring phenomena. Near-infrared (NIR) spectroscopy was utilized in screening of polymorphs and processing-induced transformations (PITs). Polymorph screening was also studied with NIR and Raman spectroscopy in tandem. Quantitative solid phase analysis during fluidized bed drying was performed with in-line NIR and Raman spectroscopy and partial least squares (PLS) regression, and different dehydration mechanisms were studied using in-situ spectroscopy and partial least squares discriminant analysis (PLS-DA). In-situ solid phase analysis with Raman spectroscopy during dissolution testing enabled analysis of dissolution as a whole, and provided a scientific explanation for changes in the dissolution rate. It was concluded that the methods applied and studied provide better process understanding and knowledge of the drug products, and therefore, a way to achieve better quality.

Investigating physical properties of solid dosage forms during pharmaceutical processing : Process analytical applications of vibrational spectroscopy

In order to improve and continuously develop the quality of pharmaceutical products, the process analytical technology (PAT) framework has been adopted by the US Food and Drug Administration. One of the aims of PAT is to identify critical process parameters and their effect on the quality of the final product. Real time analysis of the process data enables better control of the processes to obtain a high quality product. The main purpose of this work was to monitor crucial pharmaceutical unit operations (from blending to coating) and to examine the effect of processing on solid-state transformations and physical properties. The tools used were near-infrared (NIR) and Raman spectroscopy combined with multivariate data analysis, as well as X-ray powder diffraction (XRPD) and terahertz pulsed imaging (TPI). To detect process-induced transformations in active pharmaceutical ingredients (APIs), samples were taken after blending, granulation, extrusion, spheronisation, and drying. These samples were monitored by XRPD, Raman, and NIR spectroscopy showing hydrate formation in the case of theophylline and nitrofurantoin. For erythromycin dihydrate formation of the isomorphic dehydrate was critical. Thus, the main focus was on the drying process. NIR spectroscopy was applied in-line during a fluid-bed drying process. Multivariate data analysis (principal component analysis) enabled detection of the dehydrate formation at temperatures above 45°C. Furthermore, a small-scale rotating plate device was tested to provide an insight into film coating. The process was monitored using NIR spectroscopy. A calibration model, using partial least squares regression, was set up and applied to data obtained by in-line NIR measurements of a coating drum process. The predicted coating thickness agreed with the measured coating thickness. For investigating the quality of film coatings TPI was used to create a 3-D image of a coated tablet. With this technique it was possible to determine coating layer thickness, distribution, reproducibility, and uniformity. In addition, it was possible to localise defects of either the coating or the tablet. It can be concluded from this work that the applied techniques increased the understanding of physico-chemical properties of drugs and drug products during and after processing. They additionally provided useful information to improve and verify the quality of pharmaceutical dosage forms