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Biomedical subjects

C Zuñiga

Publications and source records attributed to C Zuñiga.

11 recordsLinked to original sources

Trypanosoma rangeli: increase in virulence with inocula of different origins in the experimental infection in mice.

We compared two murine models of Trypanosoma rangeli infection. The same inoculum dose and age-matched hosts were used in both cases. One group was infected with trypomastigotes obtained from passages in mice and the other, with trypomastigotes obtained from cell culture after a passage in mice. We observed that trypomastigotes obtained from the in vitro cellular infection showed increased virulence in experimental animals, with a 70% rate of death being noted in experimental mice instead of the lack of mortality seen when in vivo-derived parasites were used. The greatest levels of parasitemia and tissual lesions in the presence of the parasite also occurred when in vitro-derived parasites were used.

Animals↗

Protective effect of Trypanosoma rangeli against infections with a highly virulent strain of Trypanosoma cruzi.

We investigated the protective effect of Trypanosoma rangeli against infection with Trypanosoma cruzi in animal models of various ages and with different doses of inoculum. The age of the mice and the dose of parasites determined the course of the infection. When T. cruzi was inoculated into mice after challenge with T. rangeli, parasitaemia was more controlled, mortality decreased and histopathology showed lower inflammatory infiltration and pseudocysts. This study proposes a new murine model of the protective effect of recombinant proteins of T. rangeli for possible application in the vaccines field.

Age Factors↗

Body position effects on EMG activity of sternocleidomastoid and masseter muscles in patients with myogenic cranio-cervical-mandibular dysfunction.

This study was conducted in order to determine the effects of body position on integrated electromyographic (IEMG) activity of sternocleidomastoid and masseter muscles in 17 patients with myogenic cranio-cervical-mandibular dysfunction. EMG recordings at rest and during swallowing of saliva and maximal voluntary clenching were performed by placing surface electrodes on the sternocleidomastoid and masseter muscles (contralateral to the habitual side of sleeping of each patient), in the following body positions: standing, seated, supine, and lateral decubitus position. Significant higher EMG activities were recorded in the sternocleidomastoid muscle in the lateral decubitus position and in the supine position (except during swallowing), whereas a significant higher EMG activity was recorded in the masseter muscle during maximal voluntary clenching in standing and seated positions. The EMG pattern observed suggests that the presence of parafunctional habits and body position could be closely correlated with the clinical symptomatology in the sternocleidomastoid and masseter muscles at wakening and during waking hours, respectively, in patients with myogenic cranio-cervical-mandibular dysfunction.

Adult↗

Influence of variation in jaw posture on sternocleidomastoid and trapezius electromyographic activity.

This study was conducted in order to determine the influence of variation in the occlusal contacts on electromyographic (EMG) cervical activity in 20 patients with myogenic cranio-cervical-mandibular dysfunction. EMG recordings during maximal voluntary clenching were performed by placing surface electrodes on the left sternocleidomastoid and upper trapezius muscles in the following conditions: intercuspal position; edge to edge left laterotrusive contacts (ipsilateral); edge to edge right laterotrusive contacts (contralateral); edge to edge protrusive contacts; and retrusive occlusal contacts. A significant higher EMG activity was recorded in both muscles during maximal voluntary clenching in retrusive occlusal contact position, whereas no significant differences in EMG activity were observed between intercuspal position, ipsilateral, contralateral and protrusive contact positions. The EMG pattern observed suggests that a more frequent intensity and duration of tooth clenching in retrusive occlusal contact position could result in more clinical symptomatology in these cervical muscles in patients with myogenic cranio-cervical-mandibular dysfunction.

Adolescent↗

Influence of stabilization occlusal splint on craniocervical relationships. Part I: Cephalometric analysis.

This study was conducted in order to determine the effect of an occlusal splint on craniocervical relationships, in subjects with muscle spasms in the sternocleidomastoid and trapezius muscles. A full-arch maxillary stabilization occlusal splint was made for each of the 15 subjects. Two lateral craniocervical radiographs were taken for each subject, with and without an occlusal splint. Cephalometric analysis showed that the splint caused a significant extension of the head on the cervical spine. There was also a significant decrease in the cervical spine lordosis in the first, second and third cervical segment. These cervical changes could be a compensation mechanism caused by the extension of the cranium on the upper cervical spine. The change in the curvature implies that it is necessary to periodically evaluate the changes occurring in the craniocervical relationships after the occlusal splint has been inserted.

Adult↗

Influence of stabilization occlusal splint on craniocervical relationships. Part II: Electromyographic analysis.

The aim of this study was to determine the effect of stabilization occlusal splints on electromyographic (EMG) activity of sternocleidomastoid and trapezius muscles in subjects with spasm in the mentioned muscles. A full-arch maxillary stabilization occlusal splint was made for each of the 15 subjects. In the sternocleidomastoid muscle, tonic and saliva swallowing EMG activity decreased significantly with the splint, whereas maximal clenching activity did not change. In the trapezius muscle, no significant changes were observed with the occlusal splint. The different pattern in both muscles during tonic and swallowing EMG activity with the splint is attributed to differences in the synaptic inputs to the respective motoneuron pools, suggesting that a differential modulation of the motor neuron pools may exist of both muscles, of peripheral and/or central origin.

Adult↗

Active infective endocarditis in infants and childhood: ten-year review of surgical therapy.

We review our 10-year (June 1987-June 1997) experience in 26 children requiring early surgery due to active infective endocarditis (AIE) refractory to medical therapy. Mean age at operation was 5.0 (SD 3.5) years. Nineteen patients (73%) had predisposing factors: congenital heart disease (CHD) was the most common (10/19, 53%); endocavitary foreign materials (6/19); and previous cardiac surgery (3/19). Vegetations or valve dysfunction was detected by transthoracic echocardiography in all cases but one. Valvular location (17/26, 65%) was the most common; others locations included cardiac chambers (8/26) and intravascular thoracic aorta (1/26). Bacterial isolation was achieved in 19 patients (73%): Staphylococcus (10 patients); Streptococcus (6 patients); and Candida albicans (3 patients). The indication for surgery was progressive or persistent cardiac failure (2 patients) or infection (9 patients), or a combination of these (7 patients), despite adequate medical therapy; major embolic accident with a mobile vegetation (4 patients), recurrent pulmonary embolism with a mobile vegetation (3 patients), and mobile vegetation (> 10 mm) in left cardiac chambers (1 patient). All the patients required surgery before 6 weeks of antibiotic therapy had been completed. The hospital mortality was 19% (5/26, 70% confidential limits[CL]: 2-35%). Deaths were due to infective causes in all cases but one. No late deaths occurred in 18 patients followed up for a mean of 4.2 years (SD 2.4). Three patients needed four reoperations. We conclude that improvement in the treatment of children with AIE can be obtained with an early and accurate diagnosis, an adequate antibiotic treatment, and a more aggressive surgical approach.

Child↗

Characterization of a Trypanosoma rangeli strain of Colombian origin.

A Colombian strain of Trypanosoma rangeli was characterized by analyzing its behaviour in different axenic and cellular culture, its infection rate and the histopathological lesions produced in experimental animals. Although slight inflammatory infiltrations were shown in different histopathological sections, no pseudocysts could be observed. Grace's insect medium is better than liver infusion tryptose or artificial triatomine urine supplemented with proline when studying T. rangeli metacyclogenesis, with a peak of 32% trypomastigotes. High infection rates were found in VERO and J774 cells. Because of its 100% infectivity rates and adequacy of parasitemia levels, C23 strain is a suitable model of T. rangeli biology study.

Animals↗