Impact of tuberculosis treatment length and adherence under different transmission intensities.

Tuberculosis (TB) is a leading cause of human mortality due to infectious disease. Treatment default is a relevant factor which reduces therapeutic success and increases the risk of resistant TB. In this work we analyze the relation between treatment default and treatment length along with its consequence on the disease spreading. We use a stylized model structure to explore, systematically, the effects of varying treatment duration and compliance. We find that shortening treatment alone may not reduce TB prevalence, especially in regions where transmission intensity is high, indicating the necessity of complementing this action with increased compliance. A family of default functions relating the proportion of defaulters to the treatment length is considered and adjusted to a particular dataset. We find that the epidemiological benefits of shorter treatment regimens are tightly associated with increases in treatment compliance and depend on the epidemiological background.

Mycobacterial ecology as a modulator of tuberculosis vaccine success.

Natural infection with Mycobacterium tuberculosis, as well as cross-immune reactions with the constituent of standard vaccines, attenuated M. bovis, and other species of mycobacteria confer partial immunity to subsequent M. tuberculosis infection. It has been shown in the past that the immune response to mycobacteria found naturally in the environment reduces the benefit of vaccination as assessed by means of vaccine efficacy. In this paper we show that efficacy is a poor measure of the potential success of new anti-tuberculous vaccines due to its inability to account for the relative weight of reinfection in disease dynamics. We advocate instead the use of vaccine effectiveness when evaluating the impact of new control methods against infections that confer partial immunity. Through the study of a simple model that incorporates cross-reactive responses to environmental mycobacteria (EM) and reinfection, we show how the particulars of the relation between EM abundance and vaccine effectiveness depend on the degree of protection conferred respectively by natural infection, vaccination and EM. The relative importance of reinfection as a transmission mechanism comes up as the most important source of variability in vaccine effectiveness. Our results suggest that control efforts should be placed in reducing the importance of reinfection through diminishing transmission rates. Vaccines that overcome preexisting immunity to other mycobacteria will still have varying degrees of success depending on the underlying rate of TB transmission.

Histomorphometry and expression of Cdc47 and caspase-3 in hyperthyroid rat uteri and placentas during gestation and postpartum associated with fetal development.

In two different experiments, the effects of hyperthyroidism on the histomorphometry and expression of Cdc47 and caspase-3 were evaluated in the uteri and placentas during gestation and postpartum. Fetal development was also evaluated during gestation. In the first experiment, 36 adult female Wistar rats were divided into two groups of 18 animals each: (1) hyperthyroid; and (2) euthyroid (control). Female rats were mated and killed at 7, 14 and 19 days of gestation. Uteri and placentas were weighed and subjected to histomorphometric and immunohistochemical evaluation to determine the expression of Cdc47 and caspase-3. Ovaries were also evaluated for weight and subjected to morphometric analysis. Fetuses were quantified and weighed individually. In the second experiment, 12 adult female Wistar rats were divided into two groups of six animals each: (1) hyperthyroid; and (2) euthyroid (control). Female rats were mated and killed 2 days postpartum. Uteri were evaluated in the same way as for the first experiment. Hyperthyroidism increased ovulation and conception rates without disturbing the size and viability of the fetuses. In the pregnant uteri, hyperthyroidism did not change the thickness of the layers or the expression of Cdc47 and caspase-3. However, in the placentas, hyperthyroidism increased the medium diameter of trophoblast cells, as well as the thickness and the expression of Cdc47 of spongiotrophoblast cells, at 14 days of gestation. During uterine involution, hyperthyroidism significantly increased the expression of Cdc47 and reduced the expression of caspase-3 in the uterine layers. In conclusion, hyperthyroidism increased the conception rate because of an ovulation gain, induced significant placental changes during pregnancy and, in the uterus, increased Cdc47 expression and decreased caspase-3 expression after parturition.

Understanding the transmission dynamics of respiratory syncytial virus using multiple time series and nested models.

The nature and role of re-infection and partial immunity are likely to be important determinants of the transmission dynamics of human respiratory syncytial virus (hRSV). We propose a single model structure that captures four possible host responses to infection and subsequent reinfection: partial susceptibility, altered infection duration, reduced infectiousness and temporary immunity (which might be partial). The magnitude of these responses is determined by four homotopy parameters, and by setting some of these parameters to extreme values we generate a set of eight nested, deterministic transmission models. In order to investigate hRSV transmission dynamics, we applied these models to incidence data from eight international locations. Seasonality is included as cyclic variation in transmission. Parameters associated with the natural history of the infection were assumed to be independent of geographic location, while others, such as those associated with seasonality, were assumed location specific. Models incorporating either of the two extreme assumptions for immunity (none or solid and lifelong) were unable to reproduce the observed dynamics. Model fits with either waning or partial immunity to disease or both were visually comparable. The best fitting structure was a lifelong partial immunity to both disease and infection. Observed patterns were reproduced by stochastic simulations using the parameter values estimated from the deterministic models.

Gripenet: an internet-based system to monitor influenza-like illness uniformly across Europe.

Gripenet has been monitoring the activity of influenza-like-illness (ILI) with the aid of volunteers via the internet in the Netherlands and Belgium since 2003 and in Portugal since 2005. In contrast with the traditional system of sentinel networks of mainly primary care physicians coordinated by the European Influenza Surveillance Scheme (EISS), Gripenet obtains its data directly from the population. Any resident of the three countries can participate in Gripenet by completing an application form on the appropriate websites (http://www.griepmeting.nl for the Netherlands and Belgium, http://www.gripenet.pt for Portugal), which contains various medical, geographic and behavioural questions. Participants report weekly on the website any symptoms they have experienced since their last visit. ILI incidence is determined on the basis of a uniform case definition. In the 2006/2007 season, 19,623 persons participated in Gripenet in the Netherlands, 7,025 in Belgium and 3,118 in Portugal. The rise, peak and decline of ILI activity occurred at similar times according to Gripenet and EISS. However, ILI attack rates in the Netherlands (6.6%), Belgium (6.1%) and Portugal (5.6%) were remarkably more similar in Gripenet than in EISS (0.8%, 3.9%, and 0.6% respectively). Monitoring ILI activity with the direct participation of volunteers provides similar incidence curves compared to the traditional system coordinated by EISS. Whereas EISS provides an established system whose data is validated by virology tests, Gripenet is a fast and flexible monitoring system whose uniformity allows for direct comparison of ILI rates between countries. A current objective of Gripenet is to engage more European countries.

Chronic unpredictable mild stress decreases BDNF and NGF levels and Na(+),K(+)-ATPase activity in the hippocampus and prefrontal cortex of mice: antidepressant effect of chrysin.

Our working hypothesis is that brain neurotrophins and brain Na(+),K(+)-ATPase may be strongly associated with the occurrence of depression in animals subjected to chronic unpredictable mild stress (CUMS). Still, we believe that chrysin, a natural and bioactive flavonoid found in honey and some plants, can provide satisfactory effects on antidepressant therapy. Thus, we aimed to evaluate the effect of CUMS on brain-derived neurotropic factor (BDNF) and nerve growth factor (NGF) levels as well as the Na(+),K(+)-ATPase activity in the hippocampus and prefrontal cortex of female mice. We also aimed to examine the effect of a 28-day oral treatment with chrysin (5 or 20mg/kg) in female mice subjected to CUMS, comparing to the effect of fluoxetine. Results showed that CUMS applied for 28days induced a decrease in BDNF and NGF levels as well as in the Na(+),K(+)-ATPase activity. CUMS also promoted a depressive status in the swimming forced test (FST), in the sucrose preference test, and in corticosterone levels. Chrysin (20mg/kg) and fluoxetine also occasioned the up-regulation of BDNF and NGF levels in non-stressed mice and in mice subjected to CUMS. CUMS decreased non-protein thiol (NPSH) levels and increased reactive oxygen species (ROS) levels. In response to these changes, the glutathione reductase (GR), glutathione peroxidase (GPx) and catalase (CAT) activities were increased in mice exposed to CUMS. Chrysin and fluoxetine treatments protected against all these alterations, suggesting the involvement of the antioxidant function in the antidepressant effect of chrysin and fluoxetine. In conclusion, CUMS decreased BDNF and NGF levels as well as the Na(+),K(+)-ATPase activity in mice. Chrysin presented antidepressant effect in mice on behavioral, neurotrophic and biochemistry parameters equivalent to fluoxetine. Furthermore, we suggest that the up-regulation of BDNF and NGF levels is a mechanism possibly involved in the antidepressant effect of chrysin in mice.

Changes in collagen content in the residual myocardium surviving after infarction in rats. Influence of propranolol or hydralazine therapy.

The changes occurring in the collagen content in the residual myocardium after infarction have been poorly studied. The aim of this study was to determine the changes in the collagen content in the right and left ventricular muscle of chronically infarcted hearts. Male albino rats were submitted to ligature of the left coronary artery to produce infarction (Inf). Controls underwent a sham surgery (Sh). Inf rats were divided into groups designed to receive chronic therapy with propranolol (Prop, 1 g/l, n = 10) or hydralazine (Hydr, 0.125 g/l, n = 10) dissolved in the drinking water. One group of Inf rats (n = 12) and the Sh group (n = 10) received no treatment. The animals were killed 1 month after surgery to obtain the cardiac wet weights and to determine protein and hydroxyproline (OH-Pro) concentrations in the right ventricle (RV) free wall and in the left ventricular remaining muscle (LV), including the interventricular septum. Inf determined a 42% increase of the RV weight to body weight ratio (Sh = 0.57 +/- 0.04 mg/g; Inf = 0.81 +/- 0.06 mg/g; p < 0.05) and a 64% increase of OH-Pro concentration (Sh = 450 +/- 25 micrograms/g; Inf = 738 +/- 32 micrograms/g; p < 0.05). In Inf hearts the LV OH-Pro concentration increased similarly as in the RV. No effect of drug therapy was observed in the LV. In the RV however, propranolol reduced the hypertrophy and the OH-Pro concentration by the same amount (around 30%). Hydr on the other hand reduced OH-Pro and tended to increase hypertrophy. We conclude that a similar collagen deposition occurs in the myocardium of both ventricles after infarction in rats. Prop and Hydr were able to partially reduce this collagen increase in the right but not in the left ventricle.

Effects of aluminum on the mechanical and electrical activity of the Langendorff-perfused rat heart.

The effect of aluminum (Al3+) chloride (1, 5, 10, 50 and 100 microM) on myocardial electromechanical activity was studied in 10 Langendorff-perfused hearts from adult female Wistar rats. Al3+ decreased the development of isovolumic systolic pressure from 34.3 +/- 2.95 mmHg under control conditions to 11.8 +/- 1.53 mmHg at 100 microM AlCl3 (P < 0.01) (diastolic pressure = 0 mmHg). The atrial and ventricular rates also decreased, but only with AlCl3 concentrations greater than 1 microM (from 180 +/- 5 to 94 +/- 11 bpm for atrial rate and from 180 +/- 5 to 78 +/- 7 bpm for ventricular rate). Reduction of coronary flow was also observed, reaching 60% at 100 microM Al3+. A delay in atrioventricular conduction occurred at 10 microM Al3+, increasing progressively up to 100 microM (62.3 +/- 4 ms in the Al(3+)-free solution to 143 +/- 34 ms in the presence of 100 microM Al3+, P < 0.01, ANOVA). QRS duration did not change as a function of increasing Al3+ concentrations (37.1 +/- 1.7 ms in the Al(3+)-free solution vs 32.1 +/- 1.6 ms in the presence of 100 microM Al3+). No qualitative changes in ECG were observed. These data show that the toxic effects of Al3+ on the myocardium are reflected in reduced systolic pressure development and coronary flow and increased PR interval. These effects are discussed in terms of the inhibition of nucleotide hydrolysis by Al3+.

Neuroprotective effects of swimming training in a mouse model of Parkinson's disease induced by 6-hydroxydopamine.

Parkinson's disease (PD) is characterized by progressive dopamine (DA) depletion in the striatum. Exercise has been shown to be a promising non-pharmacological approach to reduce the risk of neurodegeneration diseases. This study was designed to investigate the potential neuroprotective effect of swimming training (ST) in a mouse model of PD induced by 6-hydroxydopamine (6-OHDA) in mice. The present study demonstrated that a 4-week ST was effective in attenuating the following impairments resulting from 6-OHDA exposure: (i) depressive-like behavior in the tail suspension test; (ii) increase in the number of falls in the rotarod test; (iii) impairment on long-term memory in the object recognition test; (iv) increase of the reactive species and interleukin 1-beta (IL-1ß) levels; (v) inhibition of the glutathione peroxidase (GPx) activity; (vi) rise of the glutathione reductase (GR) and glutathione S-transferase (GST) activities and vii) decrease of DA, homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC) levels. The mechanisms involved in this study are the modulation of GPx, GR and GST activities as well as IL-1ß level in a PD model induced by 6-OHDA, protecting against the decrease of DA, DOPAC and HVA levels in the striatum of mice. These findings reinforce that one of the effects induced by exercise on neurodegenerative disease, such as PD, is due to antioxidant and anti-inflammatory properties. We suggest that exercise attenuates cognitive and motor declines, depression, oxidative stress, and neuroinflammation induced by 6-OHDA supporting the hypothesis that exercise can be used as a non-pharmacological tool to reduce the symptoms of PD.

Localized contacts between hosts reduce pathogen diversity.

We investigate the dynamics of a simple epidemiological model for the invasion by a pathogen strain of a population where another strain circulates. We assume that reinfection by the same strain is possible but occurs at a reduced rate due to acquired immunity. The rate of reinfection by a distinct strain is also reduced due to cross-immunity. Individual based simulations of this model on a 'small-world' network show that the proportion of local contacts in the host contact network structure significantly affects the outcome of such an invasion, and as a consequence will affect the patterns of pathogen evolution. In particular, hosts interacting through a 'small-world' network of contacts support lower prevalence of infection than well-mixed populations, and the region in parameter space for which an invading strain can become endemic and coexist with the circulating strain is smaller, reducing the potential to accommodate pathogen diversity. We discuss the underlying mechanisms for the reported effects, and we propose an effective mean-field model to account for the contact structure of the host population in 'small-world' networks.

Produção e composição do leite de ovelhas Santa Inês e mestiças Lacaune e Santa Inês e desenvolvimento de seus cordeiros / Milk production and composition of Santa Inês and Lacaune x Santa Inês crossbred ewes and performance of their lambs

The effects of three maternal genotypes were evaluated on sheep milk production and composition, and on performance of their lambs during the first four months of age. The work was developed with Santa Inês and Lacaune x Santa Inês crossbred ewes. The average milk production was: ½ Lacaune, 1,550.8mL/day; ¾ Lacaune, 1,337.6mL/day; and Santa Inês, 1,005.8mL/day. There was an effect of genotype on some constituents of milk (fat and protein). For the performance of the lambs, there was an effect of maternal genotype (P<0.05) on the following biometric measurements: chest circumference, width of chest, width of rump, length of the shoulder length of leg, and perimeter of shank.

Dynamical behaviour of epidemiological models with sub-optimal immunity and nonlinear incidence.

In this paper we analyze the dynamics of two families of epidemiological models which correspond to transitions from the SIR (susceptible-infectious-resistant) to the SIS (susceptible-infectious-susceptible) frameworks. In these models we assume that the force of infection is a nonlinear function of density of infectious individuals, I. Conditions for the existence of backwards bifurcations, oscillations and Bogdanov-Takens points are given.

Desmopatia degenerativa em equinos: métodos de diagnóstico em animais vivos / Equine degenerative desmopathy: diagnostic methods in live animals

A desmopatia degenerativa (DD) possui caráter sistêmico e manifesta-se por acúmulos de proteoglicanos (PG) na matriz extracelular (MEC) de tecidos que contenham colágeno. Este estudo teve o objetivo de diagnosticar equinos suspeitos de serem acometidos por DD, em um plantel de animais de raça nacional, segundo o ângulo da articulação metatarsofalangiana (AMF) e a presença de acúmulos de PG em amostras de ligamento da nuca (LN). Analisaram-se 123 equinos clinicamente sadios e somente três (2,7 por cento) deles, segundo o ângulo AMF < 146(0), foram considerados suspeitos. Não houve diferença significativa entre os grupos. Quinze éguas foram submetidas ao exame do ângulo da AMF e à biópsia do LN, das quais sete (47,7 por cento) foram consideradas suspeitas, segundo ângulo da AMF, enquanto seis (40 por cento) apresentaram acúmulos de PG. Foram encontrados acúmulos de PG em três (20 por cento) éguas não suspeitas. Um animal suspeito não apresentou alterações histológicas compatíveis de DD.

The prevalence of degenerative desmopathy (DD) was studied in equines of national breeds, according to the metatarsophalangeal joint angle (MPA) and the presence of accumulation of proteoglycans (PG) in samples of nucal ligament (NL) from live animals, according to their age. One hundred twenty three clinically healthy horses were used. Only three (2.7 percent), that had their angle rate MPA<146º were considered suspect, with no significant difference between groups. Fifteen mares were subjected to examination of the angle of the MPA and biopsy of NL as well had reduction of the MPA angle, and six (40 percent) showed accumulation of PG. Accumulation of PG was found in three (20 percent) not suspected mares. A suspected animal showed no histological changes compatible to DD.

Efeitos dos glicosaminoglicanos e sulfato de condroitina A sobre a cartilagem articular normal e com doença articular degenerativa em cães / Glycosaminoglycans and chondroitin sulphate A effects on normal and osteoarthritic articular cartilage in dogs

Avaliaram-se os efeitos dos precursores dos glicosaminoglicanos (GAG) e do sulfato de condroitina A (SC) sobre a histomorfometria da cartilagem articular normal ou de cartilagem de cães com doença articular degenerativa (DAD) experimental. Os grupos experimentais constituíram-se de animais com articulação direita normal, que não foi submetida a procedimento cirúrgico, e com articulação esquerda osteoartrótica e que foi submetida à intervenção cirúrgica. Os grupos foram subdivididos em animais com articulação não tratada e tratada, portanto: normais (N) (n=5), NGAG (n=5) e NSC (n=4); e osteoartróticos (O) (n=5), OGAG (n=5) e OSC (n=4). Secções de cartilagens do fêmur, da tíbia e da patela foram utilizadas neste estudo. Nos normais (N, NGAG e NSC), não se encontraram lesões que caracterizassem a DAD, embora tenha havido diminuição na celularidade nos de NGAG e NSC, em relação a N. Foram observadas alterações em graus variáveis entre os grupos osteoartróticos. Houve redução acentuada dos condrócitos no grupo O em comparação aos normais enquanto os grupos osteoartróticos tratados apresentaram celularidade semelhante aos normais tratados. Estes resultados foram confirmados pela análise do índice de proporção (IP), que se mostrou elevado em O, indicando menor síntese de proteoglicanos. Não houve diferença significativa entre os IPs dos grupos osteoartróticos tratados (OGAG, OSC) apesar do comportamento distinto do OSC ao assemelhar-se aos grupos N e NSC. Estes resultados sugeriram que o SC agiu na cartilagem osteoartrótica de maneira mais eficaz, reduzindo a perda de proteoglicanos e estimulando a viabilidade celular e a atividade metabólica.

The effects of precursors of glycosaminoglycans (GAG) and chondroitin sulphate A (CS) on the histomorphometry of normal articular cartilage and with experimental degenerative joint disease (DJD) in dogs were evaluated. The groups were constituted as follows: normal joints were not undergone to the surgical procedure and left osteoarthritics that suffered surgical intervention. These were then distributed into joints that did not receive drug treatment and those that received: normal (N) (n = 5); NGAG (n = 5), and NCS (n = 4); and osteoarthritics: O (n = 5); OGAG (n = 5); and OCS (n = 4). Cartilage sections of the femur, tibia, and patella were used in this study. In normal groups (N, NGAG, and NCS) no lesions were found that could characterize DJD, although the cellularity was shown to be slightly diminished in NGAG and NCS, in relation to N. Characteristic DJD disorders were identified in variable degrees among osteoarthritic groups and were more severe in O. There was marked reduction of the number of chondrocytes in group O, as compared to the normal groups, while treated osteoathritic groups showed similar cellularity to that of normal groups. These results were supported by the analysis of the index of proportion (IP), which was high in O, indicating less synthesis of proteoglycans. These results suggest that chondroitin A sulphate acted on osteoarthritic cartilage in a more efficient way than glycosaminoglycan precursors, reducing the loss of proteoglycans caused by the degenerative process, stimulating cellular viability and metabolic activity.

Modelo experimental de trauma medular agudo produzido por aparelho estereotáxico modificado / Experimental model of acute spinal cord injury produced by modified steriotaxic equipment

Foram utilizados 55 ratos machos da espécie Rattus novergicus, variedade Wistar, com o objetivo de propor um modelo experimental de trauma medular produzido por aparelho estereotáxico modificado, capaz de reproduzir clinicamente lesões medulares padronizadas. Após realização de laminectomia dorsal de T13, utilizou-se peso compressivo de 50,5g (25 animais - grupo I) ou 70,5g (30 animais - grupo II), durante cinco minutos, comprimindo a medula espinhal. Os animais foram assistidos durante oito dias, por meio de testes comportamentais para avaliar a sensibilidade dolorosa, a capacidade motora, o posicionamento tátil e proprioceptivo e a capacidade de manter-se em plano inclinado. No grupo I, observaram-se déficits neurológicos moderados e transitórios, que variaram entre os animais. No grupo II, foi possível obter um trauma padronizado, caracterizado por paraplegia bilateral e simétrica dos membros posteriores, perda de propriocepção e da sensibilidade dolorosa de todos os animais. A utilização do aparelho estereotáxico desenvolvido permite reproduzir clinicamente trauma medular padronizado em ratos, de maneira simples, econômica e satisfatória, o que poderá proporcionar avanços nas investigações terapêuticas, abrangendo doenças neurodegenerativas, como é o caso do trauma medular agudo.

Fifty-five male rats (Rattus novergicus), Wistar variety, were used with the purpose of suggesting an experimental model of spinal cord trauma performed by using a modified stereotaxic equipment capable to reproduce clinically (standardized) pattern spinal cord injury. After dorsal laminectomy of T13, a compression was performed with 50.5g (25 animals - group I) or 70.5g (30 animals - group II) during five minutes on spinal cord. The animals were assisted during eight days by behavioral tests to evaluate painful sensibility, motor capacity, proprioceptive and tactil placing, and stability on inclined plan. In the group I, moderate and transitory neurological deficits were observed, that varied among the animals. In the group II, a standardized trauma was obtained, characterized by bilateral and symmetrical paraplegia of hindlimbs, loss of proprioception, and painful sensibility in all the animals. The use of developed stereotaxic equipment allowed to reproduce pattern spinal cord injury in rats, by a simply, economic, and satisfactory way. This can provide progresses in the therapeutic investigations embracing neurodegenerative diseases, like spinal cord injury.

Black-eye patterns: a representation of three-dimensional symmetries in thin domains.

What is believed to be the first experimental evidence for Turing patterns was observed in the CIMA reaction by De Kepper and colleagues. Ouyang and Swinney performed further experiments in a "thin" layer of gel. Patterns observed at onset were basically two-dimensional. However, beyond onset a structure that does not typically occur in two-dimensional domains was observed-the black-eye pattern. In this paper we use the full three-dimensionality of the patterned layer to find a setting where black-eye patterns naturally occur. We propose that black-eye patterns have the symmetry of a body-centered-cubic lattice.

Effects of captopril on interstitial collagen in the myocardium after infarction in rats.

BACKGROUND: Myocardial infarction is an important cause of heart failure because it cause tissue loss and contractility disturbances. In chronically infarcted hearts the increase in the collagen content in the extracellular matrix of the surviving viable myocardium has been considered a major factor contributing to development of heart failure. Postinfarction neuroendocrine activation involving the renin-angiotensin system has been implicated in this cardiac fibrosis. METHODS AND RESULTS: As collagen synthesis and degradation are dynamic processes and postinfarction remodeling is a time-dependent phenomenon, rats submitted to coronary artery ligation to produce myocardial infarction were treated with captopril after infarction (30 mg/kg, intraperitoneally, daily) to investigate whether blockade of the renin-angiotensin system can prevent postinfarction myocardial hypertrophy and reactive fibrosis. Groups of rats with myocardial infarction were treated with captopril throughout the protocol period (6 weeks), or during the first 3 weeks after infarction (early therapy), or only during the last 3 weeks of the protocol (late therapy). Untreated groups of rats with or without myocardial infarction were used as control subjects. All animals were killed 6 weeks after surgery to evaluate hypertrophy of heart chambers and collagen deposition in the right ventricle wall and in surviving left ventricular muscle. Protein and hydroxyproline concentrations were assayed biochemically in these tissue homogenates. Only rats with an infarct covering 20 to 40% of the left ventricular surface were included in the study. In the control uninfarcted group (n = 12), hydroxyproline content was 152 +/- 12 micrograms in the right ventricle and 370 +/- 30 micrograms in the left ventricle. These values increased (P < .05) to 232 +/- 13 and 630 +/- 46 micrograms, respectively, in the group with myocardial infarction (n = 8) without treatment. These values were significantly reduced (P < .05) to 160 +/- 9 micrograms in the right ventricle and 520 +/- 40 micrograms in the left ventricle in the group with myocardial infarction treated with captopril for 6 weeks. The percentage decreases in collagen content and myocardial weight produced by captopril were similar. Thus, hydroxyproline concentration (mg hydroxyproline muscle), which increases significantly in both ventricles after myocardial infarction, was not modified by captopril therapy. Protein concentration in the right and left ventricular muscles decreased after myocardial infarction. This decrease was enhanced in the infarcted groups submitted to captopril treatment, mainly in the group treated for 6 weeks. Lesser effects on hypertrophy and hydroxyproline content were observed in the groups of rats treated with captopril in only the earlier or later phase of infarction. CONCLUSIONS: It is concluded that captopril reduces similarly postinfarction hypertrophy and collagen deposition in surviving myocardium. These effects, although less intense, also occur when the drug is used for a short period immediately after myocardial infarction or when used later, when ventricular remodeling is almost fully developed.