Studies on the biology of Spirorbinae (Polychaeta)

Of four species studied, tolerance of extreme temperatures in greatest in Spirorbis pagenstecheri (which extends highest on the shore) and least in S. corallinae (which always occurs immersed in water). The latter species breeds between May and August, the other three from May to October. S. borealis liberates its larvae mainly at the moon's quarters, but this fortnightly rhythm is less obvious in S. corallinae and not found in the other two species. S. corallinae differs from S. borealis in being slower to re-emerge after disturbance and in having a lesser breeding size, maximum size and life span. Growth in the laboratory is slower in S. tridentatus than in the other species. Growth of S. borealis under natural conditions is much faster in summer than in winter.     

A possible mechanism of inhibition of protein synthesis by dimethylnitrosamine

1. The incorporation of [¹⁴C]leucine into liver proteins of rats was measured in vivo at various times after treatment of the animals with dimethylnitrosamine and was correlated with the state of the liver ribosomal aggregates. Inhibition of incorporation ran parallel with breakdown of the aggregates. 2. Inhibition of leucine incorporation into protein and breakdown of ribosomal aggregates were not preceded by inhibition of incorporation of [¹⁴C]orotate into nuclear RNA of the liver. 3. Evidence was obtained of methylation of nuclear RNA in the livers of rats treated with [¹⁴C]dimethylnitrosamine. 4. Zonal centrifugation analysis of radioactive, nuclear, ribosomal and transfer RNA from livers of rats treated with [¹⁴C]dimethylnitrosamine revealed labelling of all centrifugal fractions to about the same extent. 5. It is suggested that methylation of messenger RNA might occur in the livers of dimethylnitrosamine-treated rats and the possible relation of this to inhibition of hepatic protein synthesis is discussed.     

Lesiones histoplasmóticas autópsicas como índice epidemiológico de la enfermedad en Los Andes Venezolanos

Resumen En 244 autopsias de los años 1961, 1962 y 1963 de sujetos de más de 2 años de edad fué encontrado un 25% de casos con lesiones histoplasmóticas, en su gran mayoría de carácter residual, en pulmones y ganglios linfáticos. Esta cifra corresponde exactamente al porcentaje de reactores positivos a la prueba de histoplasmina en la población de nuestra región. Fueron corroborados los resultados deStraub &Schwarz, quienes en Cincinnati/Ohio encontraron la misma concomitancia entre los resultados de estos métodos de estudio, ambos igualmente valiosos para determinar el indice epidemiológico de histoplasmosis en una zona determinada.Puesto que en nuestros estudios no fueron aplicadas las mismas técnicas completas como en Cincinnati las cifras positivas en nuestro ambiente pueden eventualmente ser más altas, pero no alcanzan las cifras aún más elevadas, reportadas de otras zonas de Venezuela. En nuestro material el número de casos con lesiones histoplasmóticas antiguas múltiples en el pulmón, que sugieren ser primarios, era mayor que en la primera serie deStraub &Schwarz. Parece que entre nosotros la infección tiene lugar en períodos más tempranos de la vida que en EEUU de Norteamérica.El más alto índice de infección, de casi 50%, fué encontrado en personas provenientes de la región de la Cuenca del Lago de Maracaibo, disminuyendo algo en los valles de baja altura de las montañas y llegando a cifras bajas en los lugares de mayor altura.

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Summary In 244 autopsies in patients from 2 years of age on, in 1961, 1962 and 1963 histoplasmic lesions were found in 25% of all cases, mostly residual foci in lungs and lymph nodes. This percentage is exactly the same as the percentage of histoplasmin sensitivity in our environment. Thus, the results ofStraub &Schwarz who found the same percentage of anatomic lesions and histoplasmin reactors in Cincinnati, Ohio, were confirmed in our material. Morphologic methods in autopsies are a valuable tool for epidemiologic investigations regarding histoplasmosis.Since a more exact technique of examination was applied in Cincinnati, it is probable that the positive percentage in our environment is even higher. A higher number of multiple residual histoplasmotic foci in the lungs was found in our series in comparison with the first material ofStraub &Schwarz. Multiple histoplasmic foci in some of these cases may be due to primary infection. Infection withH. capsulatum occurs apparently in our environment more frequently in younger persons.The highest infection rate of almost 50% was found in patients who lived in the tropical lowlands near the Lake of Maracaibo and the Panamerican Highway. A lower rate occurred in the mountain valleys up to approximately 3000 feet of altitude, and decreased even more in higher altitudes.

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Zusammenfassung In 244 Sektionen vom 2. Lebensjahr an aus den Jahren 1961, 1962 und 1963 wurde in 25% aller Fälle Histoplasmose in Form von Residualläsionen in Lungen und Lymphknoten gefunden. Diese Zahl entspricht genau dem Prozentsatz der Bevölkerung in unserer Gegend, die positiv auf Histoplasmin reagiert. Damit werden die Befunde vonStraub &Schwarz, die an Autopsien in Cincinnati, Ohio erhoben wurden, bestätigt. Neben der Histoplasminreaktion ist es auch mittels anatomischer Untersuchungen möglich, Aussagen über das Ausmass der Infektion mitHistoplasma capsulatum in einer bestimmten Gegend zu machen.Da bei den Untersuchungen in Cincinnati genauere Untersuchungsmethoden zur Anwendung kamen, ist es möglich, dass der Prozentsatz unserer positiven Fälle eher noch höher liegt. Die Zahl unserer Fälle mit multiplen residualen Histoplasmoseherden in den Lungen ist noch höher als in der ersten Untersuchungsserie vonStraub &Schwarz. Es könnte sich in einem Teil der Fälle durchaus um multiple Primärkomplexherde handeln. Anscheinend findet die Infektion mitH. capsulatum bei uns in früheren Lebensaltern statt.Die höchste Infektionsrate von fast 50% wurde in Personen aus den gegen den Maracaibosee zu gelegenen tropischen Gebieten gefunden. Sie war etwas geringer in den Gebirgstälern bis zu etwa 1000 m Höhe und gering in Gebieten grösserer Höhe.

     

A Rapid Screening Test for Aflatoxin-synthesizing Aspergilli of the flavus-oryzae Group

A rapid test for the recognition of aflatoxin-synthesizing strains of the Aspergillus flavus–oryzae group is described. For this purpose the strains are cultivated on Czapek–Dox agar enriched with an aqueous extract of groundnuts, and in which sodium nitrate is replaced by ammonium chloride. Toxin production is observed by the production of a bright blue fluorescence in the medium when placed under an ultraviolet lamp.