Showing papers by "Federal University of Rio de Janeiro published in 1980"

Syndactyly: Frequency of specific types

Abstract: Syndactyly without other combined limb anomalies, Poland complex, or amniotic bands, was diagnosed in 174 of 599, 109 consecutive newborn infants (3/10,000). Syndactyly was the only diagnosed anomaly in 133 cases, and it was associated with other anomalies in 41. The most common type of syndactyly was isolated syndactyly of the second and third toes (70 cases), which affected more males than females, and had a higher than expected frequency of white non-Latin-European ancestry. The second most frequent type was isolated syndactyly of the middle and ring fingers (18 cases), and the third was isolated syndactyly of the fourth and fifth toes (13 cases). Considering both isolated and syndromal cases, 66% (114/172) could be assigned to one or another of the fourth genetic categories of syndactyly described by Temtamy and McKusick [1978]. This, plus the high frequency of affected first degree relatives observed (25/434:6%), suggests that the genetic forms of syndactyly may be more common than might be suspected from the small number of pedigrees in the literature.

Mutation induction by and mutational interaction between monochromatic wavelength radiations in the near-ultraviolet and visible ranges.

Abstract: — The induction of mutations (reversion to tryptophan independence) by various UV (254, 313, 334 and 365 nm) and visible (405 and 434 nm) wavelengths was measured in exponential phase populations of Escherichia coli B/r thy trp and B/r thy trp uvrA by assay of irradiated populations on semi-enriched media. No mutations were induced in the repair proficient strain at wavelengths longer than 313 nm. Mutations were induced in the excisionless strain at wavelengths as long as 405 nm but less than expected from the known amount of DNA damage induced. Irradiation at the longer wavelengths (434, 405, 365 and 334 nm) suppressed the appearance of 254- or 313-nm-induced mutations in the repair competent strain but not in the excision deficient strain. The relative dose-requirement for mutation suppression was related to the relative efficiency of these wavelengths in inducing growth delay. These results suggest that the growth delay induced by near-UV and visible wavelengths allows more time for the ‘error-free” excision repair process to act on the potentially mutagenic lesions induced by 254- and 313-nm radiations, thereby reducing the mutation frequency observed in the repair-proficient strain. The level of near-UV mutation induced in the excision deficient strain is lower than expected from the DNA damage known to be induced. It is possible that near-UV radiation induces a class of lethal lesions that are not susceptible to error-prone repair.

Influence of ionic disturbances produced by gastric washing on cortical spreading depression

Abstract: The ionic composition of the internal environment was altered in rabbits by means of gastric washing, combined with intramuscular administration of 3-Beta-aminoethylpyrazole. The effects of this treatment on cortical spreading depression (SD) were studied. C1- and Na+ concentrations decreased significantly in serum and in cerebrospinal fluid after the treatment. This made the animals much more susceptible to SD, as established by the high incidence of “spontaneous” SD, increased SD velocity of propagation and facilitated its interhemispheric transfer. An intensification of the epileptiform activity associated with SD was also observed. Intravenous replacement of NaCl abolished the above effects on SD. When the intravenous replacement was done with Na-Isethionate, those effects were enhanced. It is concluded that chloride deficiency was the main factor responsible for the observed facilitating effects.

Cálculo da evapotranspiração real na Bacia Amazônica através do método aerológico

Abstract: Resumo No presente trabalho, sao apresentados os dados obtidos para a evapotranspiracao real (ER) utilizando-se o "metodo aerologico", o qual se fundamenta no calculo da divergencia do campo do fluxo de vapor d'agua na troposfera sobre a regiao Amazonica. Faz-se um estudo comparativo com os demais resultados publicados por outros autores empregando outras metodologias e tenta-se estabelecer os limites para o valor de ER na regiao. Utilizando-se dados do periodo 1972/1975, estimou-se em 1260mm/ano o valor da ER na regiao Amazonica.

An Elementary Proof of the Polar Decomposition Theorem

Abstract: (1980). An Elementary Proof of the Polar Decomposition Theorem. The American Mathematical Monthly: Vol. 87, No. 4, pp. 288-290.

Fine structure study ofLeptomonas samueli by the freeze-fracture technique

Abstract: The ultrastructure of promastigotes ofLeptomonas samueli was studied by the freeze-fracture technique. Both the P and E faces of the plasma membrane ofL. samueli have intramembranous particles. However, the particle density was higher in the E than in the P face. The P face of the flagellar membrane had few particles whereas abundant flat membrane particles were evident on the E face. An arrangement of particles indicating membrane specializations was seen on the flagellar membrane and on the membrane lining the flagellar pocket. Cellular structures such as the nucleus, peroxisomes, the mitochondrion, and microtubules were also studied.

An electron microscopic and cytochemical study ofLeptomonas samueli

Abstract: The fine structure of promastigotes ofLeptomonas samueli is described. This protozoan revealed several features in common with other trypanosomatids. A large membrane-bound cavity containing many vesicles was observed near the nucleus. Pinocytotic vesicles were seen arising from the membrane lining the flagellar pocket. They are associated with some microtubules which originate in the flagellar pocket region and extend toward the multivesicular structure. Morphometric analysis made on electron micrographs showed a mitochondrial relative volume of 0.11 and a peroxisome relative volume of 0.08. Determination of the number of sub-pellicular microtubules in different regions of the protozoon body show that the largest number is found in the region containing the Golgi complex. Carbohydrates were detected using the periodic-acid-thiosemicarbazide-silver proteinate technique. Reaction products were seen in the plasma membrane, in the membrane of the Golgi complex, and in the membranes which form the multivesicular structure. Two cytochemical methods were used to locate basic proteins. Using the ammoniacal silver method reaction products were seen only in the nucleus. With the ethanolic phosphotungstic acid method reaction products were seen in the microtubules which form the flagellum, in the peroxisome-like organelle, and at the region of adhesion of the flagellum to the cell body.

A divergência do campo do fluxo de vapor d'água e as chuvas na região Amazônica

Abstract: Resumo Foram estimados, a partir dos dados de radiossondagens do periodo 1972/1975, os valores da divergencia do campo do fluxo de vapor d'agua sobre a bacia Amazonica. ∇.➝Q. De um modo generico, houve predominância dos valores negativos da divergencia, ficando evidenciada sua relacao com o campo da precipitacao, principalmente no mes de marco. Utilizando os valores de ∇.➝Q. estimou-se em 172.616m3/s o valor medio da vazao do rio Amazonas no periodo estudado, constituindo-se em um metodo independente para estimativas de vazao em grandes bacias, mesmo desconhecendo-se os valores da precipitacao e da evapotranspiracao. Comparacoes com outros resultados utilizando-se metodologias distintas foram feitas, tendo o metodo aerologico mestrado ser util inclusive para a previsao de vazoes mensais com antecedencia de 3 meses na bacia Amazonica. Foi de 2328mm/ano a precipitacao media no periodo estudado na bacia.

Synthesis of xyloidone and lapachone analogs

Abstract: Several xiloidone analogues were prepared, in a one step reaction, by the alkylation of lawsone with aldehydes obtained from natural essential oil sources. By Pd/C hydrogenation of these xyloidone derivatives, alpha-lapachone analogues were obtained in high yield. beta-lapachone isomers were prepared from the alpha-derivatives by treatment with sulphuric acid.

Interaction of epimastigote and trypomastigote forms of Trypanosoma cruzi with chicken macrophages in vitro

Abstract: Chicken macrophages, obtained by cultivation of blood monocytes, were infected with epimastigote and bloodstream trypomastigotes of the Y and the CL strains of Trypanosoma cruzi. The percentage of infected cells and the mean number of parasites per cell were determined after 2, 6, 12 and 24 h of parasite–cell contact. After 6 h of contact about 80% and 40% of the macrophages were infected by trypomastigotes of the Y and CL strains respectively. After longer periods of contact almost all macrophages were infected by Y trypomastigotes while only about 60% were infected by those of the CL strain. After 2 h of contact almost all macrophages were infected by CL epimastigotes while only about 50% were infected by Y epimastigotes. After 6 h of contact almost all macrophages were infected by epimastigotes of both strains. These results are discussed taking into consideration differences between parasites of the two strains and between the two developmental stages of the T. cruzi life-cycle.

Solar dosimetry and weighting factors

Abstract: Calkins and Barcello (1979) have compared action spectra for repair proficient and repair deficient organisms and concluded that the use of repair sensitive organisms as dosimeters for broad band ultraviolet (UV) sources may improperly weight the various wavelength components and lead to erroneous interpretations of results of solar UV exposure of wildtype organisms. Since the relative spectral distribution of solar radiation at wavelengths as long as 320 nm is critically dependent on latitude, time of day and season and many other environmental factors, the practical application of such weighting factors would require, in addition to a precise action spectrum for the organism and parameter under consideration, complete spectroradiometric measurements on each test day. In view of the complexity of such a procedure I would like to suggest a simple method that may be applied in certain circumstances to determine the necessity for such corrections. The initial damage leading to cell death, mutation and possibly carcinogenesis is believed to occur in the DNA. A biological dosimeter based on a UV sensitive spore has been considered for solar UV studies since it essentially integrates the relative DNA damaging capacity of sunlight on a given test day (Tyrrell, 1978a). The exponential nature of the inactivation curve, temperature independence of inactivation etc. make the manipulations and calculations extremely simple. Since the system has negligible absorption over the solar spectral region, inactivation rates can be used directly to determine the equivalent incident dose at 254 nm in terms of DNA-damaging capacity. A simple test of the necessity for weighting factors for other virtually transparent systems (such as repair competent bacteria) is to determine the equivalent dose at 254 nm (by spore dosimetry) of sunlight during the test period and then compare the results between repair competent and sensitive strains and between solar sensitivity and the sensitivity determined at 254 nm. In a series of experiments (this laboratory) with the K12 strains AB1157 (uur' rec'), AB1886 ( u w rec'), AB2463 (uur' rec) and AB2480 (uurrec) , bacterial populations were irradiated at 0°C in noon sunlight at three different times of the year. The curves constructed by plotting inactivation against the equivalent 254 nm dose were superimposable in all cases with the true 254 nm inactivation curves. Under our conditions, weighting would therefore be unnecessary. Working with noon sunlight at a tropical latitude, we are evidently optimizing the ratio of the shorter to the longer wavelengths and under conditions where this ratio changes in favour of the longer wavelengths we may expect to see some changes due to indirect effects of near-UV damage such as disruption of repair systems (for reviews see Webb, 1977; Tyrrell, 1978b). However, it is evident that spore dosimetry provides a simpler way of determining the necessity for weighting than complete spectroradiometric and action spectra measurements. The fact that both repair competent and repair sensitive strains show the solar sensitivities predicted from the relative amount of DNA damage induced may appear surprising in view of the large weighting factors assigned to the longer wavelengths by Calkins and Barcello (1979). However, it should be noted that the authors of the most detailed action spectra for lethality of repair proficient bacteria (Webb and Brown, 1976) do not consider that their spectra differ significantly from the DNA absorption spectrum at wavelengths below 320nm. Even at the more northerly latitude of Calkins and Barcello. the relative effectiveness of solar radiation between 320 and 360 nm in inactivating repair proficient bacteria is of the order of 3% that of the radiations between 290 and 320 nm for mid summer noon sunlight (calculated from action spectra and spectral irradiance data). If Webb and Brown are correct then we would expect a priori that the solar sensitivities of repair competent bacteria would be only slightly underestimated from measurements of the relative DNA damage induced. 1 would agree that weighting factors for dosimetry may well be appropriate for certain parameters such as single-cell inactivation and believe that there exists a fairly simple way of checking whether any given response deviates from that simply expected from DNA damage induction. For certain parameters, such as mutation induction. where strong wavelength interactions occur (Tyrrell, 1979) it may be practically impossible to calculate a meaningful weighting factor based on action spectra.

Cholinergic neurotransmission in retinal spreading depression.

Abstract: Experiments performed to demonstrate the participation of cholinergic synapses in retinal spreading depression (SD) have shown that: (1) acetylcholine (ACh) is liberated during SD, its concentration increasing up to 10 -4 mM in the superfusate of one eye cup; (2) the susceptibility of the retina to SD and the velocity of propagation of circling SD are influenced by cholinergic and anticholinergic drugs. ACh 1 mM is effective in eliciting the reaction, whereas d-tubocurarine 0.01 mM and atropine 0.25 mM block this effect. Prostigmine 0.075 mM is able to trigger the reaction and also potentiates the effect of ACh. The velocity of propagation is decreased by ACh 0.25–1.0 mM and prostigmine 0.030 mM, which also potentiate this effect of ACh. Pulses of d-tubocurarine 0.005–0.030 mM and atropine 0.025–0.30 mM decrease the velocity of propagation. However, they block the effect of ACh if they are continuously present in the superfusing solution; (3) the effects of ACh are not blocked by tetrodotoxin 3.19×10-3 mM.

Synthesis of sterols in Herpetomonas samuelpessoai: influence of growth conditions.

Abstract: Ergosterol was the only sterol detected in Herpetomonas samuelpessoai grown in a defined, lipid-free medium. When cultivated in a complex medium, this flagellate was found to contain 6 additional sterols. As measured by incorporation of L-[Me-14C]methionine, in the absence of acetate, the sterol synthesis was greater at 28 C than at 37 C; in the presence of acetate, however, this synthesis was greater at 37 C. When [2-14C]acetate was used as the sterol precursor, the synthesis level at 37 C exceeded that at 28 C.

Periodic and Nil Polynomials in Rings

Abstract: Let R be an associative ring and f(x1,…, xd) a polynomial in noncommuting variables. We say that f is periodic or nil in R if for all r1,…, rd ∈ R we have that f(r1,…, rd) is periodic, respectively nilpotent (recall that a ∈ R is periodic if for some integer ).