Chlamydia pneumoniae and atherosclerosis. Identification of bacterial DNA in the arterial wall

OBJECTIVE: The intracellular Gram-negative bacterium Chlamydia pneumoniae has been associated with atherosclerosis. The presence of Chlamydia pneumoniae has been investigated in fragments of the arterial wall with a technique for DNA identification. METHODS: Arterial fragments obtained from vascular surgical procedures in 58 patients were analyzed. From these patients, 39 were males and the mean age was 65±6 years. The polymerase chain reaction was used to identify the bacterial DNA with a pair of primers that codify the major outer membrane protein (MOMP) of Chlamydia pneumoniae. The amplified product was visualized by electrophoresis in the 2% agarose gel stained with ethidium bromide, and it was considered positive when migrating in the band of molecular weight of the positive controls. RESULTS: Seven (12%) out of the 58 patients showed positive results for Chlamydia pneumoniae. CONCLUSION: DNA from Chlamydia pneumoniae was identified in the arterial wall of a substantial number of patients with atherosclerosis. This association, which has already been described in other countries, corroborates the evidence favoring a role played by Chlamydia pneumoniae in atherogenesis.

Lipoprotein (a): Structure, Pathophysiology and Clinical Implications

The chemical structure of lipoprotein (a) is similar to that of LDL, from which it differs due to the presence of apolipoprotein (a) bound to apo B100 via one disulfide bridge. Lipoprotein (a) is synthesized in the liver and its plasma concentration, which can be determined by use of monoclonal antibody-based methods, ranges from < 1 mg to > 1,000 mg/dL. Lipoprotein (a) levels over 20-30 mg/dL are associated with a two-fold risk of developing coronary artery disease. Usually, black subjects have higher lipoprotein (a) levels that, differently from Caucasians and Orientals, are not related to coronary artery disease. However, the risk of black subjects must be considered. Sex and age have little influence on lipoprotein (a) levels. Lipoprotein (a) homology with plasminogen might lead to interference with the fibrinolytic cascade, accounting for an atherogenic mechanism of that lipoprotein. Nevertheless, direct deposition of lipoprotein (a) on arterial wall is also a possible mechanism, lipoprotein (a) being more prone to oxidation than LDL. Most prospective studies have confirmed lipoprotein (a) as a predisposing factor to atherosclerosis. Statin treatment does not lower lipoprotein (a) levels, differently from niacin and ezetimibe, which tend to reduce lipoprotein (a), although confirmation of ezetimibe effects is pending. The reduction in lipoprotein (a) concentrations has not been demonstrated to reduce the risk for coronary artery disease. Whenever higher lipoprotein (a) concentrations are found, and in the absence of more effective and well-tolerated drugs, a more strict and vigorous control of the other coronary artery disease risk factors should be sought.

A Novel Algorithm to Quantify Coronary Remodeling Using Inferred Normal Dimensions

Background:Vascular remodeling, the dynamic dimensional change in face of stress, can assume different directions as well as magnitudes in atherosclerotic disease. Classical measurements rely on reference to segments at a distance, risking inappropriate comparison between dislike vessel portions.Objective:to explore a new method for quantifying vessel remodeling, based on the comparison between a given target segment and its inferred normal dimensions.Methods:Geometric parameters and plaque composition were determined in 67 patients using three-vessel intravascular ultrasound with virtual histology (IVUS-VH). Coronary vessel remodeling at cross-section (n = 27.639) and lesion (n = 618) levels was assessed using classical metrics and a novel analytic algorithm based on the fractional vessel remodeling index (FVRI), which quantifies the total change in arterial wall dimensions related to the estimated normal dimension of the vessel. A prediction model was built to estimate the normal dimension of the vessel for calculation of FVRI.Results:According to the new algorithm, “Ectatic” remodeling pattern was least common, “Complete compensatory” remodeling was present in approximately half of the instances, and “Negative” and “Incomplete compensatory” remodeling types were detected in the remaining. Compared to a traditional diagnostic scheme, FVRI-based classification seemed to better discriminate plaque composition by IVUS-VH.Conclusion:Quantitative assessment of coronary remodeling using target segment dimensions offers a promising approach to evaluate the vessel response to plaque growth/regression.

Aneurisma de aorta abdominal na infância

The authors report a case of an abdominal aortic aneurism involving all visceral branches minus the Inferior Mesenteric artery in a 4-year-old girl. There was sugestive evidence that the arterial disease had an inflamatory or infectious etiologic factor. The most probable etiological factors could be salmonelas infection of the arterial wall or Takayasu's disease secondary to tuberculosis. The treatment with antibiotic to salmonelas infection during ten days, followed by tuberculostatic therapy for six months was chosen. Concerning the age, the arteries involved and the inflamatory aspect of the aneurysm, the surgical option became an alternative to the clinic treatment in case of any future evidence of the aneurysm enlargement. The patient became asymptomatic as soon as the antibiotic has been started. The control of the aneurysm evolution will be made by ecography each three months.

Bone metabolism and vascular calcification

Osteoporosis and atherosclerosis are chronic degenerative diseases which have been considered to be independent and whose common characteristic is increasing incidence with age. At present, growing evidence indicates the existence of a correlation between cardiovascular disease and osteoporosis, irrespective of age. The morbidity and mortality of osteoporosis is mainly related to the occurrence of fractures. Atherosclerosis shows a high rate of morbidity and especially mortality because of its clinical repercussions such as angina pectoris, acute myocardial infarction, stroke, and peripheral vascular insufficiency. Atherosclerotic disease is characterized by the accumulation of lipid material in the arterial wall resulting from autoimmune and inflammatory mechanisms. More than 90% of these fatty plaques undergo calcification. The correlation between osteoporosis and atherosclerosis is being established by studies of the underlying physiopathological mechanisms, which seem to coincide in many biochemical pathways, and of the risk factors for vascular disease, which have also been associated with a higher incidence of low-bone mineral density. In addition, there is evidence indicating an action of antiresorptive drugs on the reduction of cardiovascular risks and the effect of statins, antihypertensives and insulin on bone mass increase. The mechanism of arterial calcification resembles the process of osteogenesis, involving various cells, proteins and cytokines that lead to tissue mineralization. The authors review the factors responsible for atherosclerotic disease that correlate with low-bone mineral density.

The effect of siesta in parameters of cardiac structure and in interpretation of ambulatory arterial blood pressure monitoring

OBJECTIVE: To evaluate the influence of the siesta in ambulatory blood pressure (BP) monitoring and in cardiac structure parameters. METHODS: 1940 ambulatory arterial blood pressure monitoring tests were analyzed (Spacelabs 90207, 15/15 minutes from 7:00 to 22:00 hours and 20/20 minutes from 22:01 to 6.59hours) and 21% of the records indicated that the person had taken a siesta (263 woman, 52±14 years). The average duration of the siesta was 118±58 minutes. RESULTS: (average ± standard deviation) The average of systolic/diastolic pressures during wakefulness, including the napping period, was less than the average for the period not including the siesta (138±16/85±11 vs 139±16/86±11 mmHg, p<0.05); 2) pressure loads during wakefulness including the siesta, were less than those observed without the siesta); 3) the averages of nocturnal sleep blood pressures were similar to those of the siesta, 4) nocturnal sleep pressure drops were similar to those in the siesta including wakefulness with and without the siesta; 5) the averages of BP in men were higher (p<0.05) during wakefulness with and without the siesta, during the siesta and nocturnal sleep in relation to the average obtained in women; 6) patients with a reduction of 0- 5% during the siesta had thickening of the interventricular septum and a larger posterior wall than those with a reduction during the siesta >5%. CONCLUSION: The siesta influenced the heart structure parameters and from a statistical point of view the average of systolic and diastolic pressures and the respective pressure loads of the wakeful period.

Oral rapamycin attenuates atherosclerosis without affecting the arterial responsiveness of resistance vessels in apolipoprotein E-deficient mice

The objective of the present study was to assess the effects of the immunosuppressant rapamycin (Rapamune®, Sirolimus) on both resistance vessel responsiveness and atherosclerosis in apolipoprotein E-deficient 8-week-old male mice fed a normal rodent diet. Norepinephrine (NE)-induced vasoconstriction, acetylcholine (ACh)- and sodium nitroprusside (SNP)-induced vasorelaxation of isolated mesenteric bed, and atherosclerotic lesions were evaluated. After 12 weeks of orally administered rapamycin (5 mg·kg-1·day-1, N = 9) and compared with untreated (control, N = 9) animals, rapamycin treatment did not modify either NE-induced vasoconstriction (maximal response: 114 ± 4 vs 124 ± 10 mmHg, respectively) or ACh- (maximal response: 51 ± 8 vs 53 ± 5%, respectively) and SNP-induced vasorelaxation (maximal response: 73 ± 6 vs 74 ± 6%, respectively) of the isolated vascular mesenteric bed. Despite increased total cholesterol in treated mice (982 ± 59 vs 722 ± 49 mg/dL, P < 0.01), lipid deposition on the aorta wall vessel was significantly less in rapamycin-treated animals (37 ± 12 vs 68 ± 8 µm² x 10³). These results indicate that orally administered rapamycin is effective in attenuating the progression of atherosclerotic plaque without affecting the responsiveness of resistance vessels, supporting the idea that this immunosuppressant agent might be of potential benefit against atherosclerosis in patients undergoing therapy.

Drag reduction by polyethylene glycol in the tail arterial bed of normotensive and hypertensive rats

This study was designed to evaluate the effect of drag reducer polymers (DRP) on arteries from normotensive (Wistar) and spontaneously hypertensive rats (SHR). Polyethylene glycol (PEG 4000 at 5000 ppm) was perfused in the tail arterial bed with (E+) and without endothelium (E-) from male, adult Wistar (N = 14) and SHR (N = 13) animals under basal conditions (constant flow at 2.5 mL/min). In these preparations, flow-pressure curves (1.5 to 10 mL/min) were constructed before and 1 h after PEG 4000 perfusion. Afterwards, the tail arterial bed was fixed and the internal diameters of the arteries were then measured by microscopy and drag reduction was assessed based on the values of wall shear stress (WSS) by computational simulation. In Wistar and SHR groups, perfusion of PEG 4000 significantly reduced pulsatile pressure (Wistar/E+: 17.5 ± 2.8; SHR/E+: 16.3 ± 2.7%), WSS (Wistar/E+: 36; SHR/E+: 40%) and the flow-pressure response. The E- reduced the effects of PEG 4000 on arteries from both groups, suggesting that endothelial damage decreased the effect of PEG 4000 as a DRP. Moreover, the effects of PEG 4000 were more pronounced in the tail arterial bed from SHR compared to Wistar rats. In conclusion, these data demonstrated for the first time that PEG 4000 was more effective in reducing the pressure-flow response as well as WSS in the tail arterial bed of hypertensive than of normotensive rats and these effects were amplified by, but not dependent on, endothelial integrity. Thus, these results show an additional mechanism of action of this polymer besides its mechanical effect through the release and/or bioavailability of endothelial factors.

Estudo comparativo da pressão arterial e da prevalência de hipertensão arterial em duas coortes sucessivas (1975-1976) de estudantes de 16 a 25 anos, Botucatu, SP, Brasil

Com o objetivo de determinar os níveis de pressão arterial e a prevalência de hipertensão arterial em uma população jovem, foram realizados pesquisas em dois anos sucessivos em 1.288 e 736 estudantes de Botucatu, SP (Brasil) tendo sido comparados os resultados obtidos. As médias das pressões sistólicas da população estudada e dos dois grupos etários desta população (16 a 20 anos e 21 a 25 anos) foram idênticas em ambos os anos, tendo as médias das pressões diastólicas diferido de no máximo 2 mmHg; as médias, tanto sistólicas quanto diastólicas, dos dois sexos e da parcela branca da população estudada quanto à idade e sexo também diferiram de no máximo 2 mmHg. As médias da população estudada e sua parcela branca, em ambos os anos, foram superiores no sexo masculino e no grupo etário de 21 a 25 anos. Na população negra e amarela houve disparidade de resultados entre 1975 e 1976, indicando influência da exiguidade do tamanho dos contigentes negro e amarelo desta população. A prevalência de hipertensão arterial (pressão sistólica igual ou maior que 140 mmHg e diastólica igual ou maior que 90 mmHg) foi de 5,04% em 1975 e 6,22% em 1976, tendo sido em ambos os anos maior no sexo masculino do que no feminino e no grupo de 21 a 25 do que no de 16 a 20 anos.

Importância clínica dos custos diretos hospitalares em pacientes com hipertensão arterial em tratamento num hospital universitário, Rio de Janeiro, Brasil

No ano de 1978 foram registrados no Hospital Universitário da Universidade Federal do Rio de Janeiro (HU-UFRJ), 5.262 pacientes moradores da XX Região Administrativa do Rio de Janeiro, Brasil. Quinhentos e três destes prontuários (9,6%) com idade >20 anos foram separados aleatoriamente e 483 destes possuiam registro de pressão arterial (PA) com 138 casos (28,6%) apresentando hipertensão arterial (HA) (PA >140/90 mmHg). Nos 96 hipertensos inicialmente analisados procedeu-se estudos dos custos diretos hospitalares com a avaliação, acompanhamento e tratamento desta população. A PA diastólica inicial destes casos estava assim distribuída: entre 90 e 104 mmHg - 67 casos (69,8%); entre 105 e 114 mmHg - 17 casos (17,7%); maior ou igual a 115 mmHg - 12 casos (12,5%). O período médio de acompanhamento destes grupos foi de 653 dias e somente 1/3 estava com PA controlada ( < 140/90 mmHg) na última consulta. Em 1982, 68,7% já haviam abandonado tratamento no HU-UFRJ. O custo direto total anual por paciente hipertenso em dólares foi de $ 102.48 assim distribuídos: consultas ambulatoriais ligadas à HA - $ 33.44; atendimentos de emergência $ 2.33; internações $ 29.92; exames complementares $ 10.45; despesas com medicamentos anti-hipertensivos $ 26.34. As consultas e internações representam 64% dos custos e foram em grande parte determinadas pelas complicações da doença. Estas também ocasionam elevados índices de incapacidade temporária e permanente da população de hipertensos com graves repercussões e custos sociais. A análise dos fatores que contribuem para estes custos indicam a adoção das seguintes medidas para minimizá-los: a) Desenvolvimento de programas que visem melhor controle de HA e menor abandono de tratamento da população já detectada nas próprias unidades do Sistema de Saúde com conseqüente redução da morbidade da doença; b) Padronização da avaliação laboratorial e do tratamento com base em estudos de custo-eficácia; c) Hierarquização do sistema de saúde - o hipertenso deve ser tratado em unidades de saúde onde os custos indiretos hospitalares pouco influenciem os custos das consultas e das internações.

Evaluación metodológica de la relación entre presión arterial sanguinea y pliegue cutáneo: un enfoque epidemiológico

Se presentan las conclusiones de la revisión de varios trabajos que estudian la relación entre ciertas características antropométricas (pliegue del tríceps, adiposidad y circunferencia del brazo) y la presión arterial sanguinea. Después de analizar críticamente la calidad de diversos estudios basándonos en el diseño del estudio, la calidad de las mediciones y el tipo de análisis estadísticos, se encontró que en los trabajos elegidos la asociación entre el pliegue cutáneo del tríceps y la presión arterial se relaciona con tres características demográficas. Sin embargo, la pregunta sobre la independencia de esta asociación aún permanece sin respuesta. Se discute el efecto del panículo adiposo del brazo sobre la medición de la presión arterial. Se hacen una serie de recommendaciones para la medición estandarizada de la presión arterial con el fin de uniformizar el procedimiento de medida clínica y de investigación epidemiológica en esta área.

Epidemiologia da hipertensão arterial

É feita uma revisão dos conhecimentos atuais sobre a hipertensão arterial, com ênfase aos critérios de diagnóstico e à prevalência da doença no mundo.

Avaliação da ingestão dietética de cálcio em indivíduos adultos portadores de hipertensão arterial idiopática

Foi estudada a relação entre a ingestão dietética de cálcio e os demais parâmetros alimentares e antropométricos em 60 indivíduos adultos, portadores de hipertensão arterial idiopática (10 homens e 50 mulheres), com média etária de 48,6 anos, seguidos no Centro de Hipertensão Arterial do Hospital das Clínicas da Faculdade de Medicina de Botucatu (SP), Brasil. Foram utilizados três métodos diferentes de inquérito aumentar em três diferentes ocasiões: recordatório de 24h, questionário de freqüência alimentar, dirigido para ingestão de cálcio, e registro alimentar de 3 dias. As médias de ingestão de cálcio, extraídas desses inquéritos, foram semelhantes, mostrando que, em relação á ingestão de cálcio, esses métodos de inquérito alimentar podem ser utilizados indistintamente com o objetivo de se mensurar à ingestão de cálcio de um grupo de indivíduos. Além da ingestão de cálcio, foi avaliada a ingestão protéico-calórica e de diversos outros nutrientes, assim como realizada a antropometria desse grupo de hipertensos em três ocasiões diferentes, com intervalos variando de duas semanas a 15 meses. Quando comparado a um grupo de referência local, constituído de indivíduos sadios, com média etária semelhante, o grupo de hipertensos mostrou ter menor ingestão média de cálcio. Comparados por sexo, os homens dos dois grupos exibiram perfis nutricional e antropométrico semelhantes. Em relação às mulheres, houve diferenças quanto à ingestão protéico-calórica, o que se supõe ser devido à ingestão menor do leite e derivados entre as hipertensas. Estas estavam mais pesadas que as mulheres do grupo de referências, à custa de maior massa muscular, provavelmente devido a maior atividade física. Concluiu-se que o cálcio dietético foi o principal item alimentar que distinguiu hipertensos de normotensos. Como existem estudos clínicos comprovando o efeito benéfico da suplementação de cálcio na redução dos níveis pressóricos de indivíduos hipertensos, sugere-se a repetição deste tipo de trabalho, em outros locais, visando ao embasamento de programa nacional de suplementação de cálcio dietético entre indivíduos hipertensos idiopáticos.

Hipertensão arterial e possíveis fatores de risco

São apresentados resultados de um estudo de prevalência de hipertensão arterial realizado no Município de Araraquara, SP, Brasil, em 1987, que avaliou 1.199 pessoas, sendo 533 homens e 666 mulheres, de 15-74 anos de idade. Os resultados mostram alta prevalência da doença, maior no sexo masculino (32,0%) do que no feminino (25,3%), com tendência crescente com a idade, até os 49 anos (homens) e até os 59 anos (mulheres). Houve, também, maior percentagem de hipertensos nos grupos étnicos preto e pardo, nos obesos e naqueles de menor renda, menor escolaridade e ocupação em estratos inferiores. No entanto, a regressão logística mostrou "odds ratios" muito pequenos, associados a estes fatores, o que pode decorrer da maneira como os mesmos foram considerados.

Associação da pressão arterial diastólica com o tempo acumulado de trabalho entre motoristas e cobradores

Pela técnica de regressão linear múltipla, estudou-se a relação existente entre pressão arterial diastólica e as variáveis "tempo total acumulado de trabalho como condutor de veículos coletivos urbanos" e "idade", em uma população de 839 motoristas e cobradores, usuários de um serviço de saúde ocupacional da cidade de Campinas, Estado de São Paulo (Brasil). Os principais resultados encontrados foram associação positiva entre a pressão arterial diastólica e o tempo acumulado de trabalho, bem como existência de uma interação entre esta variável e a idade dos condutores.