Interactions between Polyunsaturated Fatty Acids and Probiotics

The prevalence of inflammatory based diseases has increased in industrialized countries over the last decades. For allergic diseases, two primary hypotheses have been proposed to explain this phenomenon, namely the hygiene and dietary evolution based hypothesis. Particularly, the reduced early exposure to microbes and an increase in the amount of polyunsaturated fatty acids (especially n-6 PUFA) in the diet have been discussed. Often, these two factors have been studied independently, even though both factors have been shown to possess potential health benefits and their mode of action to share similar mechanisms. The hypothesis of the present study was that demonstrate that PUFA and probiotics are not separate entities as such but do interact with each other. In the present study, we investigated whether maternal diet and atopic status influence the PUFA composition of breast milk and serum fatty acids of infants, and whether the fatty acid absorption and utilization of infant formula fatty acids is affected by supplementation of infant formula with probiotic bacteria (Lactobacillus GG and Bifidobacterium lactis Bb-12). Moreover, we investigated the mechanisms by which different PUFA influence the physicochemical and functional properties of probiotics as well as functionality of epithelial cells in vitro. We demonstrated a carry-over effect of dietary fatty acids from maternal diet via breast milk into infants’ serum lipid fatty acids. Our data confirmed the previously shown allergy –related PUFA level imbalances, though it did not fully support the impaired desaturation and elongation capacity hypothesis. We also showed that PUFA incorporation into phospholipids of infants was influenced by probiotics in infant formula in a strain dependent manner. Especially,Bifidobacterium lactis Bb-12 in infant formula promoted the utilization of n-3 PUFA. Mechanistically, we demonstrated that probiotics (Lactobacillus GG, Lactobacillus casei Shirota and Lactobacillus bulgaricus) did incorporate and interconvert exogenous free PUFA in the growth medium into bacterial fatty acids strain and PUFA dependently. In general, high concentrations of free PUFA inhibited the growth and mucus adhesion of probiotics, whereas low concentrations of specific long chain PUFA were found to promote the growth and mucus adhesion of Lactobacillus casei Shirota. These effects were paralleled with only minor alterations in hydrophobicity and electron donor – electron acceptor properties of lactobacilli. Furthermore, free PUFA were also demonstrated to alter the adhesion capacity of the intestinal epithelial cells; n-6 PUFA tended to inhibit the Caco-2 adhesion of probiotics, whereas n-3 PUFA had either no or minor effects or even promote the bacterial adhesion (especially Lactobacillus casei Shirota) to PUFA treated Caco-2 cells. The results of this study demonstrate the close and bilateral interactions between dietary PUFA and probiotics. Probiotics were shown to influence the absorption and utilization of dietary PUFA, whereas PUFA were shown to alter the functional properties of both probiotics and mucosal epithelia. These findings suggest that a more thorough understanding of interactions between PUFA and intestinal microbiota is a prerequisite, when the beneficial effects of new functional foods containing probiotics are designed and planned for human intervention studies.

Oxidized LDL and physical fitness in healthy young men: associations with body composition, smoking, metabolic syndrome and androgen status

Background: In the past, oxidized low density lipoprotein (ox-LDL) has been associated with an unbeneficial lipid profile. This atherogenic lipid profile increases the risk of atherosclerotic cardiovascular diseases. Physical fitness has substantial effect on serum lipoprotein concentration as well as body composition and humoral responses, however interrelationships between ox-LDL and physical fitness have not been widely examined in a nationally representative sample. Aims: This thesis evaluates how cardiorespiratory and muscular fitness associate with ox-LDL lipids and how the other known risk factors of atherosclerosis might alter these associations. Subjects and Methods: The study cohort consisted of 846 healthy young males (mean age 25.1, SD 4.6) who were gathered by voluntary nationwide recruitment. Each participant conducted a series of physical fitness tests (cardiorespiratory and muscular fitness) and answered a detailed questionnaire that included lifestyle habits (i.e. smoking and leisuretime physical activity). Venous blood samples including ox-LDL and serum lipids were also collected. Results: Higher levels of ox-LDL were found in overweight and obese men, however, high cardiorespiratory fitness seemed to protect the overweight from high levels of ox-LDL. Young men who smoked and had poor cardiorespiratory or muscular fitness possessed a higher concentration of ox-LDL lipids when compared to comparable levels of cardiorespiratory or muscular fitness non-smoking young men. Metabolic syndrome was associated with increased levels of ox-LDL and high levels of ox-LDL combined with poor cardiorespiratory and abdominal muscle fitness seems to predict metabolic syndrome in young men. Also, participants with poor cardiorespiratory fitness and low levels of testosterone had higher levels of ox-LDL when compared to participants with high cardiorespiratory fitness / low testosterone as well as those with poor cardiorespiratory fitness / high testosterone. Conclusions: Good cardiorespiratory and muscular fitness protects young men from increased levels of ox-LDL lipids. This association was discovered in young men who were categorized as being overweight, smokers, metabolic syndrome or with low levels of testosterone. Being fit seems to prevent higher levels of ox-LDL, even in young healthy

Mathematical modeling and optimal control of malaria

Malaria continues to infect millions and kill hundreds of thousands of people worldwide each year, despite over a century of research and attempts to control and eliminate this infectious disease. Challenges such as the development and spread of drug resistant malaria parasites, insecticide resistance to mosquitoes, climate change, the presence of individuals with subpatent malaria infections which normally are asymptomatic and behavioral plasticity in the mosquito hinder the prospects of malaria control and elimination. In this thesis, mathematical models of malaria transmission and control that address the role of drug resistance, immunity, iron supplementation and anemia, immigration and visitation, and the presence of asymptomatic carriers in malaria transmission are developed. A within-host mathematical model of severe Plasmodium falciparum malaria is also developed. First, a deterministic mathematical model for transmission of antimalarial drug resistance parasites with superinfection is developed and analyzed. The possibility of increase in the risk of superinfection due to iron supplementation and fortification in malaria endemic areas is discussed. The model results calls upon stakeholders to weigh the pros and cons of iron supplementation to individuals living in malaria endemic regions. Second, a deterministic model of transmission of drug resistant malaria parasites, including the inflow of infective immigrants, is presented and analyzed. The optimal control theory is applied to this model to study the impact of various malaria and vector control strategies, such as screening of immigrants, treatment of drug-sensitive infections, treatment of drug-resistant infections, and the use of insecticide-treated bed nets and indoor spraying of mosquitoes. The results of the model emphasize the importance of using a combination of all four controls tools for effective malaria intervention. Next, a two-age-class mathematical model for malaria transmission with asymptomatic carriers is developed and analyzed. In development of this model, four possible control measures are analyzed: the use of long-lasting treated mosquito nets, indoor residual spraying, screening and treatment of symptomatic, and screening and treatment of asymptomatic individuals. The numerical results show that a disease-free equilibrium can be attained if all four control measures are used. A common pitfall for most epidemiological models is the absence of real data; model-based conclusions have to be drawn based on uncertain parameter values. In this thesis, an approach to study the robustness of optimal control solutions under such parameter uncertainty is presented. Numerical analysis of the optimal control problem in the presence of parameter uncertainty demonstrate the robustness of the optimal control approach that: when a comprehensive control strategy is used the main conclusions of the optimal control remain unchanged, even if inevitable variability remains in the control profiles. The results provide a promising framework for the design of cost-effective strategies for disease control with multiple interventions, even under considerable uncertainty of model parameters. Finally, a separate work modeling the within-host Plasmodium falciparum infection in humans is presented. The developed model allows re-infection of already-infected red blood cells. The model hypothesizes that in severe malaria due to parasite quest for survival and rapid multiplication, the Plasmodium falciparum can be absorbed in the already-infected red blood cells which accelerates the rupture rate and consequently cause anemia. Analysis of the model and parameter identifiability using Markov chain Monte Carlo methods is presented.

Biomarkers, medical treatment and fetal intrapartum surveillance in intrahepatic cholestasis of pregnancy

Intrahepatic cholestasis of pregnancy (ICP) is a pregnancy-specific disorder characterized by maternal pruritus and elevated liver enzymes. It usually begins in the third trimester of pregnancy and resolves spontaneously after delivery. ICP is considered benign for the pregnant woman, but it is associated with an increased risk for unexplained term stillbirth and preterm delivery. There are no specific laboratory markers to diagnose ICP. The diagnosis is currently based on the presence of maternal pruritus and elevated values of alanine aminotransaminases (ALT) and serum bile acids (BA). Recently, ursodeoxycholic acid (UDCA) has been used for treatment. Mechanisms leading to intrauterine fetal death (IUFD) may be multifactorial and are unknown at present. For this thesis, 415 pregnant women with ICP were studied. The aim was to evaluate the value of the liver enzyme glutathione S-transferase alpha (GSTA) as a specific marker of ICP and to assess the effect of maternal UDCA therapy on maternal laboratory values and fetal outcome. The specific markers predisposing the fetus to heart arrhythmia were studied by comparing waveform analysis of fetal electrocardiograms (FECG) during labor in pregnancies complicated by ICP with controls. The levels of maternal GSTA were high and the values correlated with the value of ALT in patients with ICP. UDCA therapy reduced the values of the liver enzymes and alleviated maternal pruritus, but it did not influence maternal hormonal values. Although the newborns experienced an uneventful perinatal outcome, severe ICP was still associated with preterm birth and admission to the neonatal intensive care unit (NICU). There were no significant differences in intrapartum FECG findings between fetuses born to ICP women and controls.

Cancer therapy-related toxicity in the immature testis

Infertility is a common late effect of childhood cancer treatment. Testicular toxicity can clinically be first detected after the onset of pubertal maturation of the patients when the testis does not grow, spermatogenesis does not initiate and serum levels of gonadotrophins rise. Improved prognosis for childhood cancer has resulted in a growing number of childhood cancer survivors with late effects. In our study, we developed novel tools for detecting cancer therapy-related testicular toxicity during development. By using these methods the effects of the tyrosine kinase inhibitor imatinib mesylate, chemotherapy agent doxorubicin and irradiation on testicular development were investigated in rat and monkey. Patients with chronic myeloid leukemia and some patients with acute lymphoblastic leukemia have fusion gene BCR-ABL which codes for abnormal tyrosine kinase protein. Imatinib mesylate (Glivec®) inhibits activity of this protein. In addition, imatinib inhibits the action of the c-kit and PDGF –receptors, which are both important for the survival and proliferation of the spermatogonial stem cell pool. Imatinib exposure during prepubertal development disturbed the development and the growth of the testis. Spermatogonial stem cells were also sensitive to the toxic effects of doxorubicin and irradiation during the initiation phase of spermatogenesis. In addition, the effect of the treatment of acute lymphoblastic leukemia on germ cell numbers and recovery of reproductive functions after sexual maturation was investigated. Therapy for childhood acute lymphoblastic leukemia seldom results in infertility. The present study gives new information on the mechanisms by which cancer treatments exert their gonadal toxicity in immature testis.

Early nutritional determinants in cardio-metabolic programming – A prospective randomized controlled dietary intervention study

Western societies have been faced with the fact that overweight, impaired glucose regulation and elevated blood pressure are already prevalent in pediatric populations. This will inevitably mean an increase in later manifestations of cardio-metabolic diseases. The dilemma has been suggested to stem from fetal life and it is surmised that the early nutritional environment plays an important role in the process called programming. The aim of the present study was to characterize early nutritional determinants associating with cardio-metabolic risk factors in fetuses, infants and children. Further, the study was designated to establish whether dietary counseling initiated in early pregnancy can modify this cascade. Healthy mother-child pairs (n=256) participating in a dietary intervention study were followed from early pregnancy to childhood. The intervention included detailed dietary counseling by a nutritionist targeting saturated fat intake in excess of recommendations and fiber consumption below recommendations. Cardio-metabolic programming was studied by characterizing the offspring’s cardio-metabolic risk factors such as over-activation of the autonomic nervous system, elevated blood pressure and adverse metabolic status (e.g. serum high split proinsulin concentration). Fetal cardiac sympathovagal activation was measured during labor. Postnatally, children’s blood pressure was measured at six-month and four-year follow-up visits. Further, infants’ metabolic status was assessed by means of growth and serum biomarkers (32-33 split proinsulin, leptin and adiponectin) at the age of six months. This study proved that fetal cardiac sympathovagal activity was positively associated with maternal pre-pregnancy body mass index indicating adverse cardio-metabolic programming in the offspring. Further, a reduced risk of high split proinsulin in infancy and lower blood pressure in childhood were found in those offspring whose mothers’ weight gain and amount and type of fats in the diet during pregnancy were as recommended. Of note, maternal dietary counseling from early pregnancy onwards could ameliorate the offspring’s metabolic status by reducing the risk of high split proinsulin concentration, although it had no effect on the other cardio-metabolic markers in the offspring. At postnatal period breastfeeding proved to entail benefits in cardio-metabolic programming. Finally, the recommended dietary protein and total fat content in the child’s diet were important nutritional determinants reducing blood pressure at the age of four years. The intrauterine and immediate postnatal period comprise a window of opportunity for interventions aiming to reduce the risk of cardio-metabolic disorders and brings the prospect of achieving health benefits over one generation.

Metformin in gestational diabetes mellitus

METFORMIININ KÄYTTÖ RASKAUSDIABETEKSESSA Raskausdiabeteksella tarkoitetaan sokeriaineenvaihdunnan häiriötä, joka todetaan ensimmäisen kerran raskauden aikana. Hoidolla voidaan vähentää raskausdiabetekseen liittyviä äidin ja vastasyntyneen haittoja. Lääkitystä tarvitaan, jos ruokavaliohoidolla ei saavuteta hyvää sokeritasapainoa. Perinteisesti lääkityksenä on käytetty insuliinia, mutta metformii¬nin käyttöä insuliinin vaihtoehtona on ehdotettu. Metformiini läpäisee istukan, mutta sen läpäisymekanismi ei ole selvillä. Tämän tutkimuskokonaisuuden pääasiallisin tarkoitus oli verrata metformiinin tehokkuutta ja turvallisuutta insuliiniin raskausdiabeteksen hoidossa selvittämällä lääkkeen vaiku¬tusta äitiin ja vastasyntyneeseen. Lisäksi haluttiin tutkia, mitkä tekijät ennustavat insulii¬nin tarvetta metformiinin lisänä, jotta saavutettaisiin hyvä sokeritasapaino. Metformiinin annoksen vaikutus äitiin ja vastasyntyneeseen arvioitiin mittaamalla metformiinin pitoisuus äidistä, ja sikiön puolelta napanuoran veressä. Tässä tutkimuksessa selvitettiin myös aktiivisen kuljetusproteiinin (OCT) merkitystä metformiinin kulkeutumiseen istukan läpi perfusiomalla istukkaa ex vivo . Ex vivo istukkaperfuusiotutkimuksen tulokset viittasivat siihen, että OCT-kuljetusproteiinilla ei ollut todennäköisesti merkittävää osuutta metformiinin kulkeutumisessa istukan läpi. Metformiinin pitoisuusmittaukset synnytyksen yhteydessä osoittivat metformiinin siirtyvän sikiöön istukan läpi suuressa määrin (96 %) kertymättä kuitenkaan sikiön verenkiertoon. Metformiinin pitoisuudella ei ollut vaikutusta vastasyntyneen hyvinvointiin. Maksi¬maalisella metformiinin annostuksella ja korkealla metformiinipitoisuudella todettiin olevan suotuisa vaikutus äidin painon nousuun raskauden aikana. Insuliiniin verrattuna metformiini ei lisännyt äidin, sikiön tai vastasyntyneen haittatapahtumia, eikä sillä ollut vaikutusta synnytystapaan. Sokeritasapaino insuliini- ja metformiinilääkityksen aikana oli yhtäläinen arvioitaessa sitä HbA1c- ja fruktosamiinimittauksilla, mutta 21 % metformiinin käyttäjistä tarvitsi lisäksi insuliinia hyvän sokeritasapainon saavuttamiseksi. Tutkimuksesssa todettiin, että mitä iäkkäämpi äiti oli, mitä varhaisemmassa raskauden vaiheessa sokerirasitus oli tehty ja lääkitys aloitettu, ja mitä korkeammat HbA1c ja fruktosamiinipitoisuudet olivat, sitä suuremmalla todennäköisyydellä metformiinin lisänä tarvittiin insuliinia.