Could the acute strongyloides venezuelensis infection cause non-reversible host morphological changes? / A infecção aguda por strongyloides venezuelensis pode causar alterações morfológicas irreversíveis no hospedeiro? / ¿Puede la infección aguda por las strongyloides venezuelensis causar cambios morfológicos irreversibles en el hostal?

Although research has investigated the host-parasite relationship in Strongyloides venezuelensis infection in the scope of its immunological implications, the morphological consequences of this response for the host organism are yet to be explored. Our objective was to perform an organ morphometric analysis in Wistar rats infected with the intestinal parasite Strongyloides venezuelensis compared with infected rats treated with ivermectin. Twenty-six animals composed three groups: control (non-infected), infected (infected with 2,000 Strongyloides venezuelensis larvae), and infected treated (infected with 2,000 Strongyloides venezuelensis larvae and treated with ivermectin). All rodents were killed 21 days after infection and morphometric analysis of different organs was performed. The results showed significantly higher body and fecal weight in the infected-treated group. The weight of the small intestine increased considerably in the infected group and decreased in the infected-treated group. Pancreas, right kidney, and heart volume increased in the infected group compared with the control group. Despite treatment, the volumes of the stomach, brain, and left kidney increased in both the infected groups compared with the control group indicating the possibility of non- reversible host morphological adaptations. S. venezuelensis infection can augment both, volume and weight of organs ­ not necessarily related to the Strongyloides expulsion process ­ even if the acute infection had been in remission. A potential explanation for these host adaptations, including the occurrence of organ plasticity, are briefly discussed. The following steps encompass a histological analysis to verify the occurrence of hypertrophy/hyperplasia and observe if such morphological alterations remain after infection.

Embora pesquisas tenham investigado a relação parasita-hospedeiro na infecção por Strongyloides venezuelensis no âmbito de suas implicações imunológicas, as consequências morfológicas dessa resposta para o organismo hospedeiro ainda precisam ser exploradas. Nosso objetivo foi realizar uma análise morfométrica de órgãos em ratos Wistar infectados com o parasito intestinal Strongyloides venezuelensis em comparação com ratos infectados tratados com ivermectina. Vinte e seis animais compuseram três grupos: controle (não infectados), infectados (infectados com 2.000 larvas de Strongyloides venezuelensis) e tratados infectados (infectados com 2.000 larvas de Strongyloides venezuelensis e tratados com ivermectina). Todos os roedores foram sacrificados 21 dias após a infecção e a análise morfométrica de diferentes órgãos foi realizada. Os resultados mostraram peso corporal e fecal significativamente maior no grupo tratado infectado. O peso do intestino delgado aumentou consideravelmente no grupo infectado e diminuiu no grupo infectado tratado. O volume do pâncreas, rim direito e coração aumentou no grupo infectado em comparação com o grupo controle. Apesar do tratamento, os volumes do estômago, cérebro e rim esquerdo aumentaram em ambos os grupos infectados em comparação com o grupo controle, indicando a possibilidade de adaptações morfológicas não reversíveis do hospedeiro. A infecção por S. venezuelensis pode aumentar tanto o volume quanto o peso dos órgãos ­ não necessariamente relacionado ao processo de expulsão de Strongyloides ­ mesmo que a infecção aguda estivesse em remissão. Uma possível explicação para essas adaptações do hospedeiro, incluindo a ocorrência de plasticidade de órgãos, é brevemente discutida. As etapas a seguir compreendem uma análise histológica para verificar a ocorrência de hipertrofia/hiperplasia e observar se tais alterações morfológicas permanecem após a infecção.

Aunque la investigación ha investigado la relación parásito-huésped en la infección con Strongyloides venezuelensis dentro del alcance de sus implicaciones inmunológicas, aún deben explorarse las consecuencias morfológicas de esta respuesta para el organismo huésped. Nuestro objetivo fue realizar un análisis morfométrico de órganos en ratas Wistar infectadas con el parásito intestinal Strongyloides venezuelensis en comparación con ratas infectadas tratadas con ivermectina. Veintiséis animales conformaron tres grupos: control (no infectado), infectados (infectados con 2.000 larvas de Strongyloides venezuelensis) y tratados infectados (infectados con 2.000 larvas de Strongyloides venezuelensis y tratados con ivermectina). Todos los roedores fueron sacrificados 21 días después de la infección y se realizó un análisis morfométrico de diferentes órganos. Los resultados mostraron un peso corporal y fecal significativamente mayor en el grupo tratado infectado. El peso del intestino delgado aumentó considerablemente en el grupo infectado y disminuyó en el grupo tratado. El volumen de páncreas, riñón derecho y corazón aumentó en el grupo infectado en comparación con el grupo control. A pesar del tratamiento, los volúmenes de estómago izquierdo, cerebro y riñón aumentaron en ambos grupos infectados en comparación con el grupo control, lo que indica la posibilidad de adaptaciones morfológicas irreversibles del huésped. La infección con S. venezuelensis puede aumentar tanto el volumen como el peso de los órganos -no necesariamente relacionados con el proceso de expulsión de Strongyloides-, incluso si la infección aguda estaba en remisión. Se discute brevemente una posible explicación de estas adaptaciones del huésped, incluida la aparición de plasticidad de los órganos. Los siguientes pasos incluyen un análisis histológico para comprobar la hipertrofia/hiperplasia y para ver si estos cambios morfológicos permanecen después de la infección.

Anatomo-comparative study of formaldehyde, alcohol, and saturated salt solution as fixatives in Wistar rat brains.

Although formaldehyde is the most widely used and largely available fixative for preserving cadavers through decomposition prevention, it promotes darkening and weight gain, in addition to being considered carcinogenic. Ethyl alcohol has been proven a potential substitute to formaldehyde due to its effectiveness in tissue penetration, thus preventing proliferation of microorganisms; however, it can only be used alone for fixation of small parts. In view of such fixatives limitations, saturated salt solution has been widely employed based on its antimicrobial effect and ability to maintain tissue similar to the original one, in addition to exerting no hazardous effects as there is no evaporation of harmful substances. This research aimed to observe anatomical brain behaviour submitted to formaldehyde, alcohol, and saturated salt solution as fixatives. Fixatives were tested in 15 adult Wistar rats' brain, submerged in 10 ml of intended solution after removal for 4 weeks. Weight of the brains fixed in saturated salt did not change over the weeks. However, the weight of formaldehyde-fixed brains increased and the weight in alcohol-fixed brains decreased; in addition, modifications in all solutions measures were also observed. Alcohol provides a peculiar dehydrating effect as formaldehyde clearly increases the length of the pieces. Thus, since the saturated salt solution showed no important adjustment over the experimental time, it proved an efficient alternative for replacing formaldehyde and alcohol as fixative solutions of anatomical study of the brain.

Age range implications of rats over Strongyloides venezuelensis infection.

OBJECTIVE: To evaluate the dynamics of S. venezuelensis infection in Wistar rats of different age ranges. DESIGN: Thirty-five (n = 35, 7 per group) male Wistar rats were distributed according to age into five groups: 2, 3, 6, 12 and 18 months old (mo). The rats were infected by S. venezuelensis and eggs per gram of feces (EPG) were measured at 3, 9, 15 and 21 days post-infection (dpi). All animals were killed at 21 dpi, thymus, lungs and small intestines were removed, and relative weight calculated. The adult worms recovered from the small intestines and blood cells were counted. RESULTS: Rats in advanced age presented higher parasite oviposition at 9 dpi and posterior reduction of EPG, while young rats still showed higher oviposition at 15 dpi and 21 dpi. At 12 and 18 mo, the rats had greater number of adult worms, which with low fecundity, eosinophilia and least concentration of monocytes. The fecundity of worms was more expressive in young rats. A strong correlation was observed between age and EPG at 9 dpi (R = 0.72, p < 0.0001), at 15 (R = -0.66, p < 0.0001) and at 21 dpi (R = -0.65, p < 0.0001), as well as age and numbers of worms at 21 dpi (R = 0.74, p < 0.0001). The relative weight of the thymus, lungs and small intestines were higher in rats at 2 and 3 mo in comparison to the older groups of rats. CONCLUSIONS: Aging process interfered on host-parasite relationship and changed the dynamics of infection of S. venezuelensis in Wistar rats.

Electroacupuncture in rats infected with Strongyloides venezuelensis: effects on gastrointestinal transit and parasitological measurements.

OBJECTIVE: To investigate the effects of electroacupuncture (EA) at ST36 and CV12 on gastrointestinal transit and parasitological measurements during Strongyloides venezuelensis infection in rats. DESIGN: Rats were infected with S. venezuelensis and allocated to one of three groups that were infected and remained untreated (SV group, n=8), infected and treated with EA at CV12 (SV+CV12 group, n=8) or infected and treated with EA at ST36 (SV+ST36 group, n=8). EA was performed every 3 days over a 21-day period, at 4 mA intensity and 15 Hz frequency for 20 min. At 2 and 20 days post-infection (dpi), body weight, food and water intake, and faecal characteristics were monitored over a 24-hour period. Gastric emptying, caecal arrival time, small intestinal transit and eggs per gram (EPG) of faeces were calculated at 3, 9, 15 and 21 dpi. At 21 dpi, intestinal worm recovery was counted. RESULTS: EA at ST36 and CV12 slowed gastric emptying over the course of infection time. An accelerated intestinal transit was observed in the ST36 group, and after CV12 treatment the same effect was observed at 9 and 15 dpi. At 9 dpi, EPG was increased in the CV12 group. ST36 treatment decreased EPG at 9 and 15 dpi. At 21 dpi, both the ST36 and CV12 groups had increased EPG and worm numbers. No changes were observed in the other parameters analysed. CONCLUSIONS: EA at ST36 and CV12 provoked changes in gastrointestinal transit that may be beneficial to the host during S. venezuelensis infection; however, based on the number of worms and EPG at 21 dpi, the indication for EA in the treatment of strongyloidiasis needs to be carefully assessed.

Early cardiac hypertrophy induced by thyroxine is accompanied by an increase in VEGF-A expression but not by an increase in capillary density.

Cardiac hypertrophy in response to hyperthyroidism is well known. However, the effects on cardiac microcirculation are still controversial in this model. The present study evaluated the effects of acute administration of two different thyroxine (T4) dose levels on the angiogenic response in the myocardium. Capillary density (CD), the CD to fiber density (FD) ratio (CD/FD), and intercapillary distance (ICD) were assessed, as was ventricle weight (VW) to body weight (BW) ratio (VW/BW). Collagen I and III messenger ribonucleic acid (mRNA) expression and VEGF-A expression were also determined by reverse transcriptase polymerase chain reaction (RT-PCR). Immunohistochemical detection of proliferating cell nuclear antigen (PCNA) expression in endothelial cell nuclei was also carried out. We simulated an acute hyperthyroidism situation in male Wistar rats by daily intraperitoneal injection of T4 (0.025 or 0.1 mg kg(-1) day(-1)) for 7 days. Hemodynamic parameters showed that T4 did not alter systolic blood pressure (SBP) but significantly increased heart rate (HR). Both T4 doses significantly increased VW. Morphologically, the higher T4 dose resulted in a 33% greater myocardial mass, which was not accompanied by alterations in collagen I and III mRNA expression. The CD and CD/FD parameters were significantly lower in the hyperthyroid rats treated with the higher dose than in the control animals, and PCNA-labeling analysis indicated total absence of marked capillary growth. However, although the acute treatment with T4 did not induce any alteration in capillary number and endothelial cell proliferation, the vascular endothelial growth factor (VEGF)-A mRNA and protein expression were significantly increased with the higher T4 dose. These data indicate that the cardiac hypertrophy induced by acute treatment with thyroid hormone precedes the angiogenic process, which probably occurs later.