89 resultados para hybrid form


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SUMMARY Toxoplasmosis, a worldwide highly prevalent zoonotic infection, is transmitted either by the oocysts, from water and soil, or the tissue cysts, in raw or undercooked infected meat, of Toxoplasma gondii. An ongoing debate is whether there are differences between the clinical and epidemiological characteristics of the outbreaks due to one or the other infective form of the agent. We performed a systematic review, recovering 437 reported outbreaks of which 38 were selected. They were complete reports containing ascribed Toxoplasma infecting form, and clinical and demographic data. There was no gender or age group selection in the outbreaks, which were described more often in the Americas. A large number of individuals were affected when oocysts, associated with soil and water contaminated with cat feces, were considered the transmission source. Onset of symptoms occurred early when the infection was ascribed to meat tissue cysts (11.4 ± 6.7 days) with sharpened temporal distribution of cases, while a broader and prolonged appearance of new cases was observed when oocysts in water were the source of the infection (20 ± 7 days, p < 0.001). Such information may be useful in the design and implementation of control strategies.

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Data on the epidemiology and the natural history of the indeterminate form of human chronic Chagas' disease (IFCCD) are discussed, revealing its great importance in endemic areas of Brazil. The work shows that IFCCD presents a gradual and very slow course, causing a benign picture in the studied patients. Evolution patterns, prognostic and anatomopathological features are also discussed. For practical purposes, the classical concept of IFCCD proved to be simple, operational and consistent, It is defined by the absence of symptoms and clinical findings in chronic infected patients with positive serology and/or parasitological examinations for Trypanosoma cruzi coupled with normal electrocardiographic and radiological exams (heart, oesophagus and colon X-Rays). If a patient is submitted to more rigorous and sophisticated tests, these can reveal some alterations, generally small ones and unable to interfere with the prognosis of the infection. It is suggested that research lines specially related to the evolution ary factors and immunological involvement during this phase be adopted.

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A new Trypanosoma cruzi stock isolated from a patient in the chronic phase of Chagas' disease with the digestive and cardiac fortn of the disease was characterized by experimental infection in isogenic, susceptible, A/Sn strain mice. Parasitemia curves showed up to 1.7x10(6) parasites/ml and no mortality was observed up to 300 days post infection. Specific IgM was found in mice in the acute phase up to 40 days and also in the chronic phase. IgG antibodies yvere detected in the acute and chronic phase. Histopathology examination demonstrated myotropism to the digestive tract muscle layers and to the heart.

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Four cases of severe pulmonary form of leptospirosis (SPFL) are described. In all four of these blood culture proven cases, there was severe pulmonary injury characterized by alveolar hemorrhage and acute respiratory failure. Three patients died in less than 48 hours after onset of the first respiratory signs. Leptospiral antigen detection in lung tissues was positive by immunoperoxidase in all three of these cases, suggesting that the microorganism exerts a local direct destructive action. Patients with SPFL should be carefully monitored, as the abrupt onset of severe alveolar hemorrhage can lead to respiratory insufficiency and death. The authors emphasize the importance of radiological findings and blood gas analysis for prompt clinical diagnosis, and suggest that corticosteroids, associated with antibiotics, early respiratory support, and platelet transfusions are useful as an attempt to prevent further development of SPFL.

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INTRODUCTION: Authors describe human schistosomal granuloma in late chronic phase, from the morphological and evolutionary viewpoints. METHODS: The study was based on a histological analysis of two fragments obtained from a surgical biopsy of peritoneum and large intestine of a 42-year-old patient, with a pseudotumoral form mimicking a peritoneal carcinomatosis associated to the schistosomiasis hepatointestinal form. RESULTS: Two hundred and three granulomas were identified in the pseudotumor and 27 in the intestinal biopsy, with similar morphological features, most in the late chronic phase, in fibrotic healing. A new structural classification was suggested for granulomas: zone 1 (internal), 2 (intermediate) and 3 (external). CONCLUSIONS: Regarding granuloma as a whole, we may conclude that fibrosis is likely to be controlled by different and independent mechanisms in the three zones of the granuloma. Lamellar fibrosis in zone 3 seems to be controlled by matrix mesenchymal cells (fibroblasts and myoepithelial cells) and by inflammatory exudate cells (lymphocytes, plasmocytes, neutrophils, eosinophils). Annular fibrosis in zone 2, comprising a dense fibrous connective tissue, with few cells in the advanced phase, would be controlled by epithelioid cells involving zone 1 in recent granulomas. In zone 1, replacing periovular necrosis, an initialy loose and tracery connective neoformation, housing stellate cells or with fusiform nuclei, a dense paucicellular nodular connctive tissue emerges, probably induced by fibroblasts. In several granulomas, one of the zones is missing and granuloma is represented by two of them: Z3 and Z2, Z3 and Z1 or Z2 and Z1 and, ultimately, by a scar.

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Introduction This study evaluated the level of concordance between hybrid capture II (HCII) and PapilloCheck® for the detection of high-risk human papillomavirus (HPV) in anal samples. Methods Anal cell samples collected from 42 human immunodeficiency virus (HIV)+ patients were analyzed. Results Considering only the 13 high-risk HPV types that are detectable by both tests, HCII was positive for 52.3% of the samples, and PapilloCheck® was positive for 52.3%. The level of concordance was 80.9% (Kappa = 0.61). Conclusions Good concordance was observed between the tests for the detection of high-risk HPV.

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Two cytotypes (2n=4x=36 and 2n=6x=54) found in Salvinia minima Bak. are discussed, the first from Brazil and the second from Argentina. The hexaploid cytotype, presumably a hybrid between Salvinia minima and S. sprucei Kuhn, was collected from the Solimões River near Manaus, Brazil and from Trinidad. Discussing its intermediate morphology, the authors attemp to explain the hybridization as a result of the seasonal and sporadic occurrence of Salvinia sprucei in the Amazonian basin, assuming that the still unknown chromosome number of the latter species would correspond to the diploid level (2n=2x=18).

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OBJETIVOS: Verificar a prevalência de sintomas depressivos em mulheres com câncer de mama e identificar os fatores de risco associados à sua ocorrência. MÉTODOS: Foi realizado um estudo transversal, em que foram entrevistadas 71 mulheres com câncer de mama. Foram empregados dois instrumentos: um questionário para verificar os dados sociodemográficos e clínicos e o Inventário de Depressão de Beck - Short Form (BDI-SF), para avaliação dos sintomas depressivos. Para análise dos dados, utilizaram-se medidas descritivas e o teste de qui-quadrado, que avaliou a associação entre variáveis sociodemográficas e clínicas e os sintomas depressivos. O nível de significância considerado foi de 5%. RESULTADOS: A prevalência de sintomas depressivos foi de 29,6%. Os fatores associados à presença desses sintomas foram o tratamento quimioterápico (p = 0,021), presença de dor (p = 0,018) e limitação do movimento do membro superior (p = 0,010) e pior percepção da saúde (p = 0,018). CONCLUSÃO: Sintomas depressivos são frequentes no câncer de mama, assim a saúde mental das mulheres com esse tipo de câncer deve ser investigada e tratada quando necessário, reduzindo o impacto desses sintomas na vida da mulher.

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OBJECTIVE: To identify and associate potential electrocardiographic and echocardiographic changes in patients with the indeterminate form of Chagas' disease during long-term follow-up. METHODS: One hundred sixty patients underwent standard electrocardiography and two-dimensional guided M-mode echocardiography for left ventricular ejection fraction determination. Patients were followed up for 98.6±30.4 months, undergoing repeat electrocardiographic studies at 6-month intervals and echocardiographic studies at 12-month intervals. RESULTS: Based on the electrocardiographic findings, the patients were divided into group I, 125 patients (78.6%) with normal electrocardiograms throughout follow-up, and group II, 34 patients (21.3%) who developed electrocardiographic changes. Group II was further divided into group IIA (9 patients, 5.6%) with permanent electrocardiographic changes, group IIB (14 patients, 8.8%) with transitory electrocardiographic changes, and group IIC (11 patients, 6.9%) with changes appearing only on the final electrocardiogram. Left ventricular ejection fractions remained normal in the entire population studied and did not differ among groups. CONCLUSION: The indeterminate form of Chagas' disease clearly represents a benign condition with a favorable long-term prognosis. Although some patients develop electrocardiographic changes, left ventricular systolic function is well preserved.

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The authors describe a case of pericardial effusion accompanied by cardiac tamponade caused by primary hypothyroidism. Diagnosis was made by exclusion, because other causes of cardiac tamponade are more frequent. Emergency treatment of cardiac tamponade is pericardiocentesis (with possible pericardial window), and, after stabilization, performance of hormonal reposition therapy with L-thyroxin.

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Marfan's syndrome is an inherited disorder of the connective tissue. Cardiologic manifestations, especially aortic dilation, are important causes of morbidity and mortality in the clinical course of the disease in adults and teenagers. In children, the presence of aortic aneurysm and its dissection or rupture is rare, occurring in patients with genetic mutation of the fibrillin gene but not in those who have the familial form of the disease. We describe here 2 patients, from the same family (siblings), diagnosed with gigantic aortic aneurysm early in infancy, one of them successfully undergoing surgery.

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Background: Patients with indeterminate form of Chagas disease/cardiac normality (ICD/CN) exhibited normal electrocardiograms and chest X-rays; however, more sophisticated tests detected some degree of morphological and functional changes in the heart. Objective: To assess the prevalence of systolic and diastolic dysfunction of the right ventricle (RV) in patients with ICD/CN. Methods: This was a case–control and prevalence study. Using Doppler two-dimensional echocardiography (2D), 92 patients were assessed and divided into two groups: group I (normal, n = 31) and group II (ICD/CN, n = 61). Results: The prevalence of RV systolic dysfunction in patients in groups I and II was as follows: fractional area change (0.0% versus 0.6%), mobility of the tricuspid annulus (0.0% versus 0.0%), and S-wave tissue Doppler (6.4% versus 26.0%, p = 0.016). The prevalence of global disorders such as the right myocardial performance index using tissue Doppler (16.1% versus 27.8%, p = 0.099) and pulsed Doppler (61.3% versus 68%, p = 0.141) and diastolic disorders such as abnormal relaxation (0.0% versus 6.0%), pseudonormal pattern (0.0% versus 0.0%), and restrictive pattern (0.0% versus 0.0%) was not statistically different between groups. Conclusion: The prevalence of RV systolic dysfunction was estimated to be 26% (S wave velocity compared with other variables), suggesting incipient changes in RV systolic function in the ICD/CN group.

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1) It may seem rather strange that, in spite of the efforts of a considerable number of scientists, the problem of the origin of indian corn or maize still has remained an open question. There are no fossil remains or archaeological relics except those which are quite identical with types still existing. (Fig. 1). The main difficulty in finding the wild ancestor- which may still exist - results from the fact that it has been somewhat difficult to decide what it should be like and also where to look for it. 2) There is no need to discuss the literature since an excellent review has recently been published by MANGELSDORF and REEVES (1939). It may be sufficient to state that there are basically two hypotheses, that of ST. HILAIRE (1829) who considered Brazilian pod corn as the nearest relative of wild corn still existing, and that of ASCHERSON (1875) who considered Euchlaena from Central America as the wild ancestor of corn. Later hypotheses represent or variants of these two hypotheses or of other concepts, howewer generally with neither disproving their predecessors nor showing why the new hypotheses were better than the older ones. Since nearly all possible combinations of ideas have thus been put forward, it har- dly seems possible to find something theoretically new, while it is essential first to produce new facts. 3) The studies about the origin of maize received a new impulse from MANGELSDORF and REEVES'S experimental work on both Zea-Tripsacum and Zea-Euchlaena hybrids. Independently I started experiments in 1937 with the hope that new results might be obtained when using South American material. Having lost priority in some respects I decided to withold publication untill now, when I can put forward more concise ideas about the origin of maize, based on a new experimental reconstruction of the "wild type". 4) The two main aspects of MANGELSDORF and REEVES hypothesis are discussed. We agree with the authors that ST. HILAIRE's theory is probably correct in so far as the tunicata gene is a wild type relic gene, but cannot accept the reconstruction of wild corn as a homozygous pod corn with a hermaphroditic tassel. As shown experimentally (Fig. 2-3) these tassels have their central spike transformed into a terminal, many rowed ear with a flexible rachis, while possessing at the same time the lateral ear. Thus no explanation is given of the origin of the corn ear, which is the main feature of cultivated corn (BRIEGER, 1943). The second part of the hypothesis referring to the origin of Euchlaena from corn, inverting thus ASCHERSON's theory, cannot be accepted for several reasons, stated in some detail. The data at hand justify only the conclusion that both genera, Euchlaena and Zea, are related, and there is as little proof for considering the former as ancestor of the latter as there is for the new inverse theory. 5) The analysis of indigenous corn, which will be published in detail by BRIEGER and CUTLER, showed several very primitive characters, but no type was found which was in all characters sufficiently primitive. A genetical analysis of Paulista Pod Corn showed that it contains the same gene as other tunicates, in the IV chromosome, the segregation being complicated by a new gametophyte factor Ga3. The full results of this analysis shall be published elsewhere. (BRIEGER). Selection experiments with Paulista Pod Corn showed that no approximation to a wild ancestor may be obtained when limiting the studies to pure corn. Thus it seemed necessary to substitute "domesticated" by "wild type" modifiers, and the only means for achieving this substitution are hybridizations with Euchlaena. These hybrids have now been analysed init fourth generation, including backcrosses, and, again, the full data will be published elsewhere, by BRIEGER and ADDISON. In one present publication three forms obtained will be described only, which represent an approximation to wild type corn. 6) Before entering howewer into detail, some arguments against ST. HILAIRE's theory must be mentioned. The premendelian argument, referring to the instability of this character, is explained by the fact that all fertile pod corn plants are heterozygous for the dominant Tu factor. But the sterility of the homozygous TuTu, which phenotypically cannot be identified, is still unexplained. The most important argument against the acceptance of the Tunicata faetor as wild type relic gene was removed recently by CUTLER (not yet published) who showed that this type has been preserved for centuries by the Bolivian indians as a mystical "medicine". 7) The main botanical requirements for transforming the corn ear into a wild type structure are stated, and alternative solutions given. One series of these characters are found in Tripsacum and Euchlaena : 2 rows on opposite sides of the rachis, protection of the grains by scales, fragility of the rachis. There remains the other alternative : 4 rows, possibly forming double rows of female and male spikelets, protection of kernels by their glumes, separation of grains at their base from the cob which is thin and flexible. 8) Three successive stages in the reconstruction of wild corn, obtained experimentally, are discussed and illustrated, all characterized by the presence of the Tu gene. a) The structure of the Fl hybrids has already been described in 1943. The main features of the Tunicata hybrids (Fig. -8), when compared with non-tunicate hybrids (Fig. 5-6), consist in the absence of scaly protections, the fragility of the rachis and finally the differentiation of the double rows into one male and one female spikelet. As has been pointed out, these characters represent new phenotypic effects of the tunicate factor which do not appear in the presence of pure maize modifiers. b) The next step was observed among the first backcross to teosinte (Fig. 9). As shown in the photography, Fig. 9D, the features are essencially those of the Fl plants, except that the rachis is more teosinte like, with longer internodes, irregular four-row-arrangement and a complete fragility on the nodes. c) In the next generation a completely new type appeared (Fig. 10) which resembles neither corn nor teosinte, mainly in consequence of one character: the rachis is thin and flexible and not fragile, while the grains have an abscission layer at the base, The medium sized, pointed, brownish and hard granis are protected by their well developed corneous glumes. This last form may not yet be the nearest approach to a wild grass, and I shall try in further experiments to introduce other changes such as an increase of fertile flowers per spikelet, the reduction of difference between terminal and lateral inflorescences, etc.. But the nature of the atavistic reversion is alveadwy such that it alters considerably our expectation when looking for a still existing wild ancestor of corn. 9) The next step in our deductions must now consist in an reversion of our question. We must now explain how we may obtain domesticated corn, starting from a hypothetical wild plant, similar to type c. Of the several changes which must have been necessary to attract the attention of the Indians, the following two seem to me the most important: the disappearance of all abscission layers and the reduction of the glumes. This may have been brought about by an accumulation of mutations. But it seems much more probable to assume that some crossing with a tripsacoid grass or even with Tripsacum australe may have been responsible. In such a cross, the two types of abscission layer would be counterbalanced as shown by the Flhybrids of corn, Tripsacum and Euchlaena. Furthermore in later generations a.tu-allele of Tripsacum may become homozygous and substitute the wild tunicate factor of corn. The hypothesis of a hybrid origin of cultivated corn is not completely new, but has been discussed already by HARSHBERGER and COLLINS. Our hypothesis differs from that of MANGELSDORF and REEVES who assume that crosses with Tripsacum are responsible only for some features of Central and North American corn. 10) The following arguments give indirects evidence in support of our hypothesis: a) Several characters have been observed in indigenous corn from the central region of South America, which may be interpreted as "tripsacoid". b) Equally "zeoid" characters seem to be present in Tripsacum australe of central South-America. c) A system of unbalanced factors, combined by the in-tergeneric cross, may be responsible for the sterility of the wild type tunicata factor when homozygous, a result of the action of modifiers, brought in from Tripsacum together with the tuallele. d) The hybrid theory may explain satisfactorily the presence of so many lethals and semilethals, responsible for the phenomenon of inbreeding in cultivated corn. It must be emphasized that corn does not possess any efficient mechanism to prevent crossing and which could explain the accumulation of these mutants during the evolutionary process. Teosinte which'has about the same mechanism of sexual reproduction has not accumulated such genes, nor self-sterile plants in spite of their pronounced preference for crossing. 11) The second most important step in domestication must have consisted in transforming a four rowed ear into an ear with many rows. The fusion theory, recently revived byLANGHAM is rejected. What happened evidently, just as in succulent pXants (Cactus) or in cones os Gymnosperms, is that there has been a change in phyllotaxy and a symmetry of longitudinal rows superimposed on the original spiral arrangement. 12) The geographical distribution of indigenous corn in South America has been discussed. So far, we may distinguish three zones. The most primitive corn appears in the central lowlands of what I call the Central Triangle of South America: east of the Andies, south of the Amazone-Basin, Northwest of a line formed by the rivers São Prancisco-Paraná and including the Paraguay-Basin. The uniformity of the types found in this extremely large zone is astonishing (BRIEGER and CUTLER). To the west, there is the well known Andian region, characterized by a large number of extremely diverse types from small pop corn to large Cuszco, from soft starch to modified sweet corn, from large cylindrical ears to small round ears, etc.. The third region extends along the atlantic coast in the east, from the Caribean Sea to the Argentine, and is characterized by Cateto, an orange hard flint corn. The Andean types must have been obtained very early, and undoubtedly are the result of the intense Inca agriculture. The Cateto type may be obtained easily by crosses, for instance, of "São Paulo Pointed Pop" to some orange soft corn of the central region. The relation of these three South American zones to Central and North America are not discussed, and it seems essential first to study the intermediate region of Ecuador, Colombia and Venezuela. The geograprical distribution of chromosome knobs is rapidly discussed; but it seems that no conclusions can be drawn before a large number of Tripsacum species has been analysed.

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The occurrence of hybrid dysgenesis was investigated in Drosophila sturtevanti Duda, 1927 using diagnostic crosses similar to those used for induction of dysgenics traits in D. melanogaster. Reciprocal test crosses were made, at 27° C, between an old laboratory strain of D. sturtevanti (COL, from Colombia), assumed to be an M'-like strain, and eight freshly collected strains from several natural populations. The gonadal dysgenesis indices were under 10% in most of crosses, except in hybrids of COL with I27, a strain from Minas Gerais (Brazil), in which the index values were moderate in both directions of crosses (25.71 and 12.87). The smallest productivity was also observed in hybrids of females COL mated to I27 males. No causal relationship between the observed gonadal dysgenesis and mobilization of P element or another transposable element could be effectively established.