Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 5 uppsatser.

Diss. (sammanfattning) Linköping : Linköpings universitet, 2007. / Härtill 5 uppsatser.

Background & Aims: The 'high-density lipoprotein (HDL) hypothesis', that therapeutic interventions directed at raising HDL cholesterol might translate into improved cardiovascular outcomes, has been confounded by recent reports from genetic and pharmacological studies. HDL functionality may be more important than cholesterol cargo. HDL cholesterol levels are normal or even high in Type 1 Diabetes (T1DM) but do not seem to protect against atherosclerosis as might be expected; this thesis aims to offer new insight into HDL functionality through examination of these patients. This thesis also aims to improve understanding of the qualitative changes in lipoproteins associated with diabetes and increased cardiovascular morbidity, with emphasis on atherogenic modifications of apolipoprotein B and sphingolipids, and consideration of the relationship between these changes, novel and established biomarkers, and macrovascular and microvascular diabetic complications. Materials & Methods: Patients with Type 1 (n = 91) and Type 2 (n = 40) Diabetes Mellitus and healthy volunteers (n = 104) attended for fasting blood tests, urinalysis, and examination including cardiac computed tomography, carotid doppler studies and assessments of nerve function. In vitro studies of lipoprotein modification used pooled human plasma. Results: Lipoprotein glycation represents an atherogenic modification. In vitro glycation occurs more readily in the presence of physiological concentrations of copper. HDL and copper-selective chelation with triethylenetetramine prevents glycation. Glycated apolipoprotein B, oxidized LDL and small-dense LDL levels were significantly higher in T1DM; HDL cholesterol levels were also significantly higher, but with altered apolipoprotein distribution, and significantly lower cholesterol efflux capacity and PON1 activity than in healthy controls. Significant changes were also observed in cystatin C, advanced glycation end-products, leucine-rich alpha-2-glycoprotein, lipoprotein-associated phospholipase A2, a variety of inflammatory markers, and sphingolipid and ceramide profiles. Discussion: Cardiovascular disease is the leading cause of death and disability in diabetes. Patients with diabetes show qualitative and kinetic lipoprotein abnormalities, and any cardiovascular benefit associated with intensive glucose lowering may be related to effects on lipoprotein metabolism rather than directly through altered glycaemia. The apparently relatively undisturbed lipid profile observed in many patients with diabetes hides major atherogenic changes and altered HDL functionality, which may be at least partially responsible for the persistent increased risk of cardiovascular disease in patients with diabetes. HDL-based therapy remains a largely unfulfilled promise, but there may be a role for copper-selective chelation and more aggressive low-density lipoprotein lowering in the reduction of diabetic complications.

Neste estudo observamos os efeitos da ausência de receptores para LDL sobre os níveis plasmáticos de colesterol, pressão arterial, controle reflexo da freqüência cardíaca, nitratos totais e estresse oxidativo em eritrócitos e tecido cardíaco. Para tanto utilizamos camundongos controle (n=13, para avaliações hemodinâmicas e de estresse oxidativo, e n=11, para dosagem de colesterol), e Knockout para receptores de LDL controle (n= 6, para avaliações hemodinâmicas e de estresse oxidativo, e n=5, para dosagem de colesterol). Como análise estatística utilizamos o teste T de Student para amostras não pareadas, considerando-se significativo quando p<0,05. A ausência desses receptores aumentou os níveis plasmáticos de colesterol total em mg/dL (179± 35) no grupo knockout (KO), em relação ao controle (109± 13). Esse resultado foi acompanhado pelo aumento da pressão arterial média (PAM) em mmHg no grupo KO (140±3), quando comparado ao controle (118±6). A freqüência cardíaca basal não foi significativamente diferente entre os grupos, mas o reflexo comandado pelos pressoreceptores estava significativamente atenuado nos animais KO. Tanto em eritrócitos como no tecido cardíaco, a atividade das enzimas antioxidantes apresentou-se significativamente reduzida; e o dano oxidativo, expresso pela dosagem de carbonilas e quimiluminescência, esteve significativamente aumentado no grupo KO. Esses resultados foram acompanhados pela redução dos níveis de nitratos totais, indicando uma redução da biodisponibilidade de óxido nítrico circulante nesses animais. Esses resultados indicam que a ausência de receptores para LDL não só causam aumento dos níveis de colesterol sangüíneo, mas também do estresse oxidativo. Esses aumentos poderiam estar contribuindo tanto para aumentar a degradação do óxido nítrico quanto para reduzir sua síntese, resultando em aumento da PA e prejuízo da sensibilidade barorreflexa, observados nesse estudo.

The aim of optimalization the insemination doses production is to provide the highest fertilization ability of spermatozoa during the demanding proces of processing fresh semen and its subsequent cryopreservation. Temperature changes causes spermatozoa damage during the cooling and freezing. Spermatozoa is exposed to cold shock and many others limiting factors, which leads to cell death and therefore to decline of fertilization ability of thawed insemination doses. For increasing spermatozoa resistance, exactly the plasma membrane resistance against cold shock was fraction of egg yolk LDL cholesterol (low density lipoprotein) at various concentrations into the comercially produced diluents added. It is believed that LDL acts possitively to plasma membrane and helps to maintain the fertilization ability of spermatozoa after thawing. Following step in the proces of insemination doses production is slow cooling of diluted semen and equilibration, when the straws are store at cooling box for 30 minutes to 240 hours. This period is necessary to penetrate of certain diluent components into the spermatazoa also maintain the balance between their intracellular and extracellular concentration. Also important is subsequent freezing temperature gradient of insemination doses. The most suitable freezing method is based on computer controlled temperature decline in freezing chamber which allows the precise control of ice crystals formation that could tear and kill the cell. During 2012 to 2016 was repeatedly collected semen from the group of breeding bulls (n = 27, Holstein and Czech Fleckvieh breed) at AI centre. Semen which fulfill the standard entrance conditions in first step was evenly into several parts divided. For dilution the three types of comercially diluents AndroMed, Bioxcell and Triladyl with and without LDL addition were used. Into the diluents AndroMed and Bioxcell the concentration of LDL 4 %, 6 % and 8% into the dilent Triladyl 6 %, 8 % and 10 % was added. Diluted semen was filled into the glass capillares with volume 0,1 ml and temperature +4 °C. Subsequently the sample was placed to cold bath (0°C) for 10 minutes. Then the volume of capillare with physiological solution (37 °C) was mixed and for next 120 minutes was incubate. The effect of cold shock to proportion of live spermatozoa was evaluated by using Eosin and Nigrosine staining technique during heat test of spermatozoa survivability after spermatozoa heating and after 120 minutes of incubation. The more suitable semen diluents which provide the higher spermatozoa resistance against cold shock were AndroMed and Bioxcell. Together the possitive effect of LDL addition into the diluents to lower decrease of proportion of live spermatozoa during heat test was found (P<0.05). The most suitable LDL concentration which had a favorable influence at spermatozoa resistance against cold shock was 6 % in diluent Bioxcell. Values of the proportion of live sperm were higher at the beginning of the heat test (+1.31% to + 3.2%) and after 120 minute incubation (+5.82% to +8.41%) compared to other diluents with and without addition of LDL. In the next step the process of equilibration was optimized, is an important part of insemination doses production. The effect of the length of equilibration for subsequent fertilization ability of spermatozoa was evaluated using spermatozoa motility based of CASA and proportion of live spermatozoa after thawing and during heat survival test lasting 120 minutes (37 ° C). Suitable semen was diluted by comercially used diluent AndroMed based on soya lecithin, filled into the straws (0.25 ml), cooled and equilibrated in cooling box for 30, 120 and 240 minutes and freezed in programmable freezing box applying four types of freezing curves differing in temperature rate decline. There was used standard and by producer recommended 3. phase freezing curve, then 2. phase freezing curve, and 3. phase freezing curve with slower as well as rapid decline of temperature rate in freezing chamber, compared with standard freezing curve. The highest spermatozoa motility was found using 240 minutes of equilibration by +2.72% and +4.58% compared to other lengths of equilibration (P <0.05 to 0.01). The highest proportion of live spermatozoa was found using 120 minutes of equilibration (+6.87 % and +8.68 %). The highest average spermatozoa motility during heat test after thawing was achieved by using 2. phase freezing curve (from +2.97% to +10.37%, P <0.05), also in the proportion of live spermatozoa (from + 4.37% to +8.82%, P <0.01). When evaluating interaction between the length of equilibration and freezing curve (standard 3. phase and 2 . phase freezing curve), the highest average spermatozoa motility and proportion of live spermatozoa using 240 minutes of equilibration by both freezing curves was reached, there was no statistically significant differences. As well as, in all evaluated parts of this study the individual differences between ejaculate of bulls and within semen from one bull (P <0.05) as secondary effect were found. To maintain good fertilization ability of semen during cryopreservation is necessary to increase the spermatozoa resistance against cold shock using addition of correct concentration of LDL into the commercially used diluents AndroMed and Bioxcell. Subsequently the fertilization ability of insemination dose is influenced by cooling, the length of equilibration and freezing. The length of equilibration 120 minutes and more as well as gentle way of freezing according to freezing curve, which ensures a gradual decrease of temperature in freezing chamber provided the higher average spermatozoa motility and proportion of live spermatozoa.

Submitted by Pós graduação Farmácia (ppgfar@ufba.br) on 2017-04-24T17:46:02Z No. of bitstreams: 1 Dissertação_Ana_Karina_Souza_Leal.pdf: 2268804 bytes, checksum: d3093aabfde93dc9cb194dc5cad02adb (MD5) / Approved for entry into archive by Patricia Barroso (pbarroso@ufba.br) on 2017-04-24T23:16:39Z (GMT) No. of bitstreams: 1 Dissertação_Ana_Karina_Souza_Leal.pdf: 2268804 bytes, checksum: d3093aabfde93dc9cb194dc5cad02adb (MD5) / Made available in DSpace on 2017-04-24T23:16:39Z (GMT). No. of bitstreams: 1 Dissertação_Ana_Karina_Souza_Leal.pdf: 2268804 bytes, checksum: d3093aabfde93dc9cb194dc5cad02adb (MD5) / Introdução. Embora as doenças cardiovasculares (DCV) geralmente se manifestem na vida adulta, o processo aterosclerótico inicia-se na infância. Estudos mostram que indivíduos portadores de modificações ateroscleróticas precoces e mais graves possuem um ou mais fatores e marcadores equivalentes de risco cardiovascular na vida adulta como, dislipidemia, hipertensão, obesidade e hiperglicemia. Objetivos. Identificar marcadores plasmáticos, histológicos e imunohistoquímicos de gênese e progressão da aterosclerose humana precoce e crônica em amostras de plasma e fragmentos vasculares de pacientes submetidos à revascularização miocárdica. Casuística e Métodos. Foram avaliadas amostras de plasma e tecido vascular de 23 pacientes de ambos os gêneros, 44 a 73 anos, em dois grupos > 56 e < 56 anos, da Unidade de Cirurgia de Revascularização Miocárdica (RM) /Hospital Ana Nery/UFBA, com indicação de RM, entre Dez/2009 e Jun/2012. Foi determinado perfil lipídico, calculados indicadores de risco cardiovasculares e marcações para os receptores LDL-r, CD36 e CD68 em fragmentos de aorta e torácica interna. Resultados. Os dados do perfil lipídico entre os grupos dito crônico (> 56 anos) e dito precoce (< 56 anos) foram diferentes (p < 0,05). Os índices calculados no grupo < 56 anos estavam acima dos valores de referência. Em ambos os grupos, o índice de Gazziano (TG/HDL-C) indicou presença de LDL pequenas e densas. O grupo < 56 anos, mostra valores de tamanho de LDL inferiores (7,1 ± 1,4 vs 4,15 ± 2,9) quando comparados ao grupo > 56 anos, respectivamente. O não-HDL-C mostrou-se mais graves no grupo < 56 anos em função da hipertrigliceridemia (234±58mg/dL; p=0,0006). Nos estudos histológicos e imunohistoquímicos, observou-se aterosclerose discreta e marcações com diferentes intensidades entre os dois grupos para LDL-r, CD36 e CD68. Nos < 56 anos, observou-se estrias lipídicas, macrófagos degenerados, cristais de colesterol, basofilia de fibras elásticas e pontos hemorrágicos. A marcação para LDL-r nos >56 anos, mostrou-se difusa. Na torácica interna, as marcações foram focais e de baixa intensidade, porém, menos intensas do que nos < 56 anos. A marcação CD36 na torácica interna foi intensa nos pacientes < 56 anos, quando comparada com os cortes dos > 56 anos. A marcação para CD68 nos cortes de aorta foi intensa em ambos os grupos, porém, nos cortes de torácica interna a marcação foi tênue independente do grupo avaliado. Para o CD36, os dados apontam para risco em < 56 anos, em função da marcação intensa observada, esse receptor está implicado na gênese do processo aterosclerótico. Conclusões. Pode-se conceber que existe interação importante entre os marcadores plasmáticos e teciduais atuando no evento aterogênico, sendo mais graves em pacientes com menos de 56 anos. / Introduction. Although cardiovascular disease (CVD) often manifest in adulthood, the atherosclerotic process begins in childhood. Studies show that individuals with early atherosclerotic changes possess one or more equivalent factors and markers of cardiovascular risk in adult life as dyslipidemia, hypertension, obesity and hyperglycemia. Objective. Identify plasma markers, histological and immunohistochemical features of the genesis and progression of atherosclerosis in early human plasma samples and fragments of vascular patients undergoing myocardial revascularization. Casuistic and Methods. Samples of plasma and vascular tissue from 23 patients of both genders, 44 to 73 years, in two groups >56 and <56 years, from Myocardial Revascularization (MR) Surgery Unit / Ana Nery’s Hospital / UFBA, indicated to MR, between Dec/2009 Jun/2012. Lipid profile, calculated indices of cardiovascular risk markers and receptors for LDL-r, CD36 and CD68 in fragments and internal thoracic aorta was determined. Results. Lipid profile data between groups said as chronic (> 56 years) and said as precocious (<56 years) were different (p <0.05). The indices in the group <56 years were above the reference values. In both groups, the rate of Gazziano (TG / HDL-C) indicates the presence of small, dense LDL. The group <56 years, shows lower LDL size values (7.1 ± 1.4 vs 4.15 ± 2.9) when compared to > 56 years group, respectively. The non-HDL-C was more severe in the group <56 years due to hypertriglyceridemia (234 ± 58mg/dL, p = 0.0006). In histological and immunohistochemical studies, were observed discrete atherosclerosis and marks with different intensities between the two groups for LDL-r, CD36 and CD68. In <56 years, were observed lipid streaks, degenerate macrophages, cholesterol crystals, basophilia of elastic fibers and bleeding points. The markup for LDL-r in > 56 years was diffused. In internal thoracic, the tissue marks were of low intensity and focally localized, but less intense when compared to <56 years group. The internal mammary CD36 mark was high in patients <56 years, when compared with > 56 years. The marks for CD68 in aorta was intense in both groups, however, in internal thoracic was tenuous independent of evaluated group. For CD36, the data point to risk from <56 years, due to the intense labeling observed, this receptor is really implicated in the pathogenesis of atherosclerosis. Conclusion. It is conceivable that there is significant interaction between the plasma and tissue markers acting in atherogenic event, being most severe in patients younger than 56 years.

Neste estudo observamos os efeitos da ausência de receptores para LDL sobre os níveis plasmáticos de colesterol, pressão arterial, controle reflexo da freqüência cardíaca, nitratos totais e estresse oxidativo em eritrócitos e tecido cardíaco. Para tanto utilizamos camundongos controle (n=13, para avaliações hemodinâmicas e de estresse oxidativo, e n=11, para dosagem de colesterol), e Knockout para receptores de LDL controle (n= 6, para avaliações hemodinâmicas e de estresse oxidativo, e n=5, para dosagem de colesterol). Como análise estatística utilizamos o teste T de Student para amostras não pareadas, considerando-se significativo quando p<0,05. A ausência desses receptores aumentou os níveis plasmáticos de colesterol total em mg/dL (179± 35) no grupo knockout (KO), em relação ao controle (109± 13). Esse resultado foi acompanhado pelo aumento da pressão arterial média (PAM) em mmHg no grupo KO (140±3), quando comparado ao controle (118±6). A freqüência cardíaca basal não foi significativamente diferente entre os grupos, mas o reflexo comandado pelos pressoreceptores estava significativamente atenuado nos animais KO. Tanto em eritrócitos como no tecido cardíaco, a atividade das enzimas antioxidantes apresentou-se significativamente reduzida; e o dano oxidativo, expresso pela dosagem de carbonilas e quimiluminescência, esteve significativamente aumentado no grupo KO. Esses resultados foram acompanhados pela redução dos níveis de nitratos totais, indicando uma redução da biodisponibilidade de óxido nítrico circulante nesses animais. Esses resultados indicam que a ausência de receptores para LDL não só causam aumento dos níveis de colesterol sangüíneo, mas também do estresse oxidativo. Esses aumentos poderiam estar contribuindo tanto para aumentar a degradação do óxido nítrico quanto para reduzir sua síntese, resultando em aumento da PA e prejuízo da sensibilidade barorreflexa, observados nesse estudo.

Made available in DSpace on 2014-06-11T19:23:01Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-08-30Bitstream added on 2014-06-13T18:50:11Z : No. of bitstreams: 1 neo_ta_me_arafcf.pdf: 1125295 bytes, checksum: 23377b72364333a1ac1bf48473dfab17 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O vírus da Hepatite C (VHC) é o principal agente etiológico das hepatites não-A e não-B, infectando aproximadamente 170 milhões de pessoas no mundo (3% da população mundial). O vírus da hepatite C (HCV; hepatitis C-virus) é envelopado tem de 50 a 70nm de diâmetro, possui uma única fita positiva de RNA e pertence ao gênero do Hepacivirus e à família Flaviridae. Seu genoma é constituído por cerca de 9.500 nucleotídeos com regiões curtas não codificadoras e hiperconservadas nas extremidades 5’ e 3’UTR, flanqueando uma única ORF. A região estrutural do vírus é constituída por 3 genes: core, E1 e E2. As proteínas do envelope, E1 e E2 do VHC, são altamente glicosiladas e apresentam 30 e 70 kDa, respectivamente. Estudos demonstram que ambas apresentam funções específicas em diferentes etapas do ciclo de replicação do vírus, atuando de forma essencial para entrada, ligação ao receptor e fusão com a membrana da célula hospedeira. A glicoproteína E2 do VHC liga-se com alta afinidade a uma alça do receptor CD81, também denominado de TAPA-1, uma tetraespanina encontrada na superfície de muitas células, incluindo hepatócitos. No entanto, o CD81 isoladamente não é suficiente para mediar a entrada celular do vírus, e vários outros co-fatores podem atuar nessa interação. Os receptores de lipoproteína de baixa densidade (LDL-r) e receptor scavenger tipo B classe I apresentam grande importância nessa relação com o VHC. Estudos sobre as glicoproteínas E1 e E2 têm mostrado que estas se associam com os LDL-r, sugerindo que o VHC use estes receptores para invadir a célula hospedeira. Além disso, estudos anteriores relatam o fato de que, as lipoproteínas poderiam proporcionar acréscimos da infectividade ao VHC. Desta forma, neste trabalho foram desenvolvidas estratégias de clonagem e expressão heteróloga da proteína E2, e avaliou-se sua imunogenicidade... / Hepatitis C is currently recognized as the primary cause of hepatitis non A - non B associated to the blood transfusion. The hepatitis C virus (HCV) is enveloped in about 50 to 70nm in diameter, presenting a positive single strand RNA and belongs to the genus Hepacivirus and the family Flaviridae. Its genome consists of 9,500 nucleotides with short non-coding regions and hiperconservadas ends 5´ and 3'UTR flanking a single ORF. The virus structural region is based on three core genes, E1 and E2. HCV E1 and E2 are highly glycosylated and have 30 and 70 kDa, respectively. Studies show that both have key role in different stages of the cycle of virus replication, acting as essential for entry, receptor binding and fusion with host cell membrane. Glycoprotein E2 of HCV binds with high affinity to a loop of CD81, a tetraspanin, also named TAPA-1, found on the surface of many cells, including hepatocytes. However, the CD81 alone is not sufficient to mediate the cellular entry of the virus, and several other co-factors may be operating in this interaction. Recipients of low density lipoprotein (LDL-r) and scavenger receptor class B type I (SR-BI) would present great importance in relation to HCV. The LDL-r plays an important role in infection for virus of the hepatitis C. Studies on the glycoproteins E1 and E2 have shown that these are associated with the LDL-r suggesting that HCV uses the LDL-r to invade the host cell. Besides, previous studies showed that lipoprotein could improve HCV infectivity. Thus, in this work the capacity of recognition of the antibodies present anti-HCV was evaluated in the positive human serum for HCV of recognizing the protein E2 recombinant produced in bacteria of the lineage Rosetta and also the capacity of connection of the protein E2 of HCV in bind LDL-r present in the surface of human cells with characteristics endoteliais (ECV 304), and such capacity was... (Complete abstract click electronic access below)

Sammanfattning Bakgrund Insjuknande i hjärtinfarkt har minskat kraftigt i Sverige de senaste åren men drabbar fortfarande många. Ateroskleros i hjärtats kranskärl är den viktigaste bakomliggande orsaken. Utvecklingen av ateroskleros sker under lång tid och processen är komplex men kan kopplas till inflammatoriska processer, apoB-innehållande lipoprotein och endoteldysfunktion. LDL bedöms av många forskare vara en kausal faktor vid aterosklersutvecklingen. Denna bedömning grundar sig på djurförsök, observationsstudier, resultat från kliniska prövningar med LDL-sänkande läkemedel samt mendelska randomiseringsstudier. Behandlingsrekommendationerna vid sekundärprevention av hjärtinfarktpatienter innefattar behandling med hög dos statin där vissa av rekommendationerna sätter upp ett mål på en LDL-sänking till nivåer under 1.8 mmol/l. Syfte Syftet med detta arbete var att undersöka vilka behandlingseffekter som finns vid läkemedelsbehandling som sänker LDL till låga nivåer vid sekundärprevention för hjärtinfarktpatienter och om de nuvarande behandlingsriktlinjerna på nivåer under 1.8 mmol/l kan anses rimliga. Vidare gjordes en ansats för att belysa frågan om huruvida LDL-sänkning eller pleiotropa effekter kan förklara effekten vid statinbehandling. Resultat Behandling med hög dos statin som sänker LDL till låga nivåer minskar risken för större kardiovaskulära/koronara händelser. Effekten beror främst på minskat antal hjärtinfarkter och revaskulariseringsprocedurer. Effekten på koronar/kardiovaskulär mortalitet förefaller emellertid vara i bästa fall liten. Samma mönster sågs i studier av PCSK9-hämmaren evolocumab och NPC1L1-hämmaren ezetimib. Då dessa läkemedel sänker LDL genom andra mekanismer än statiner indikerar detta att LDL-sänkning i sig har en effekt men pleiotropa effekter kan inte uteslutas. Slutsats Läkemedelsbehandling som sänker LDL till nivåer under 1.8 mmol/l förefaller ha effekt och därmed är det inte orimligt att ha ett sådant behandlingsmål. Det går emellertid inte att finna en optimal nivå för LDL-koncentrationen i plasma baserat på de studier som gjorts. NNT-talen blir relativt höga och en betydande residualrisk kvarstår även vid sänkning till låga LDL-nivåer vilket indikerar potentiell vikt av tidigare insatt LDL-sänkande behandling men även ett behov av nya behandlingsformer / Summary Background Despite substantial reductions in the incidence of myocardial infarction, the incidence remains high. Rupture of an atherosclerotic plaque within the coronary arteries is the most important direct causal factor. Atherosclerosis typically develops slowly and silently and can be described as a build-up of cholesterol-containing plaques within the artery wall. Theories of the causal mechanisms behind atherosclerosis point to a high degree of complexity. Most theories focus on an interaction between inflammatory processes, cholesterol-containing lipoproteins and dysfunction of the endothelial cells within the artery wall. Much focus has been put on the role of cholesterol-containing low-density lipoprotein (LDL). This lipoprotein seems to have a direct causal role in the process. Such a standpoint is based on animal experiments, observational studies, randomized clinical trials with LDL-lowering drugs and Mendelian randomization studies. Treatment guidelines for patients with myocardial infarction therefore recommend LDL-lowering therapy. These guidelines recommend treatment with a high dose statin and some include recommendations to lower LDL to levels below 1.8 mmol/l (69 mg/dl). Objective The aim of this thesis was to look at the treatment effects of lowering LDL to low levels for secondary prevention of myocardial infarction and whether the current recommendations of 1.8 mmol/l or less are reasonable. A second objective was to elucidate the question of whether statins have other, pleiotropic effects beside their LDL-lowering capacity. Searches were conducted in pubmed for randomized clinical statin-trials where low average LDL-levels were obtained. Further, a trial with PCSK9-inhibitor evolocumab and a trial with NPC1L1-inhibitor ezetimibe were included in order that the effects of these drugs could be compared with the effects of statins. Thereby, the question of statin-pleiotropy could be analyzed. Results Treating patients with a high dose statin to obtain lower levels of LDL reduced the risk of major coronary/cardiovascular events when compared with a low dose statin. The absolute risk reduction was however low. The effect was driven mainly by a reduction in the number of myocardial infarctions and coronary revascularization procedures whereas the effects on mortality seem absent or at best rather modest. The same pattern was seen in the FOURIER-trial where PSCK9-inhibitor evolocumab was compared with standard statin treatment. The active treatment group obtained an average LDL-level of 0.78 mmol/l (30 mg/dl). This pattern was also seen in the IMPROVE-IT-trial, where NPC1L1-inhibitor ezetimibe was compared with standard statin treatment. Conclusion Treatment to obtain low levels of LDL have an effect - even at levels below 1.8 mmol/l. LDL-lowering in and of itself seems to have an effect given the results from studies where patients were treated with evolocumab and ezetimibe. The number of patients that need to be treated to prevent one event is however high and a substantial number of patients remain at risk even at very low levels of LDL. This implies the need for other forms of therapy or initiation of LDL-lowering therapies at earlier stages for selected groups of patients before they experience a myocardial infarction

Neste estudo observamos os efeitos da ausência de receptores para LDL sobre os níveis plasmáticos de colesterol, pressão arterial, controle reflexo da freqüência cardíaca, nitratos totais e estresse oxidativo em eritrócitos e tecido cardíaco. Para tanto utilizamos camundongos controle (n=13, para avaliações hemodinâmicas e de estresse oxidativo, e n=11, para dosagem de colesterol), e Knockout para receptores de LDL controle (n= 6, para avaliações hemodinâmicas e de estresse oxidativo, e n=5, para dosagem de colesterol). Como análise estatística utilizamos o teste T de Student para amostras não pareadas, considerando-se significativo quando p<0,05. A ausência desses receptores aumentou os níveis plasmáticos de colesterol total em mg/dL (179± 35) no grupo knockout (KO), em relação ao controle (109± 13). Esse resultado foi acompanhado pelo aumento da pressão arterial média (PAM) em mmHg no grupo KO (140±3), quando comparado ao controle (118±6). A freqüência cardíaca basal não foi significativamente diferente entre os grupos, mas o reflexo comandado pelos pressoreceptores estava significativamente atenuado nos animais KO. Tanto em eritrócitos como no tecido cardíaco, a atividade das enzimas antioxidantes apresentou-se significativamente reduzida; e o dano oxidativo, expresso pela dosagem de carbonilas e quimiluminescência, esteve significativamente aumentado no grupo KO. Esses resultados foram acompanhados pela redução dos níveis de nitratos totais, indicando uma redução da biodisponibilidade de óxido nítrico circulante nesses animais. Esses resultados indicam que a ausência de receptores para LDL não só causam aumento dos níveis de colesterol sangüíneo, mas também do estresse oxidativo. Esses aumentos poderiam estar contribuindo tanto para aumentar a degradação do óxido nítrico quanto para reduzir sua síntese, resultando em aumento da PA e prejuízo da sensibilidade barorreflexa, observados nesse estudo.