Polyuridylic sequences and negative strands of Sindbis virus-specific RNAs: study by affinity chromatography on poly (A)-sepharose columns (author''s transl)

The experimental conditions of affinity chromatography on poly (A)-Sepharose columns have been determined. This method makes obvious the existence of polyuridylic acid sequences on the negative strands of Sinbis virus-spedific RNAs. The isolated RNAs are negative and positive strands hybrids. By polyacrylamide gel electrophoresis, it has been shown that the negative strands have the same length as the 26 S interjacent RNA at the 6th hour, and as the 42 S virion RNA at the 9th hour postinfection. The polyadenylic acid sequences of the virion RNA and of the replicative intermediate are therefore probably genetically coded.     

Histologic structures preserved for 21,300 years

Histologic examination of rehydrated tissue samples from late Pleistocene (Alaskan) mammal mummies demonstrates that the preservative effect of freezing and drying extends to remains 15,000 to 25,000 years old. Some muscle and liver tissue retained identifiable histologic structures. Most tissues were completely disintegrated and partly replaced by masses of bacteria, an indication of considerable postmortem decay before the remains were entombed beneath the permafrost zone.     

Ultrastructure and elemental composition of dormant and germinating Diplodia maydis spores

The ultrastructure of Diplodia maydis spores was studied in thin sections with a transmission electron microscope. Storage vacuoles were evenly distributed in the two cells. Some of the vacuoles that contained a dense osmiophilic sphere(s) were surrounded by a membrane, and had membranous aggregates around their periphery. The sport wall was composed of an electron-dense layer and an electron-translucent layer. An inner cytoplasmic membrane was present. Dormant and germinating spores were studied with scanning electron microscopy and also with a Si (Li) energy-dispersive X-ray analyzer. The dormant spore was ovate and usually two-celled with a central septum. Germination proceeded via a germ tube from the side of one end of the cell. Of several methods for preparation of specimens for X-ray analysis studied, freeze-dried spores mounted on carbon stubs and then further carbon coated gave the best results. X-ray analyses revealed that spore populations contained large amounts of Si, P, Cl, and K, smaller amounts of S and Ca, and trace amounts of Mg and Al. Analyses of single spores revealed high K and Cl and low P and Mg at one end of the cell with concomitant low K and Cl and high P and Mg in the central portion and other end of the cell. In two-celled germinating spores, high K and Cl occurred in the end of the nongerminating spore cell, whereas the germinating cell contained high P and Mg and low K and Cl. X-ray image maps revealed that K and Cl were located together at one end of the spore.     

Dose-rate dependence of heat radiosensitization

The dose rate dependence of heat radiosensitization was studied using rat astrocytoma cells in culture and a clinically relevant protocol of heat dose and heat radiation sequence. Cells were treated with a minimally toxic heat dose of 43 degrees C for 30 minutes, after which they were irradiated with varying doses of radiation at dose rates ranging from 0.567 to 300 cGy/min. This heat dose substantially reduced the extrapolation number (n), but had little effect on Do of the radiation survival curve at dose rates of 50 cGy/min or greater. At dose rates less than 10 cGy/min, 43 degrees C for 30 min had little effect on n and only for the lowest dose rate studied (0.567 cGy/min) was there a significant reduction in Do (60%). The thermal enhancement ratio did not vary inversely with radiation dose rate over the dose rate range studied but, instead, was maximal at the two dose rate extremes (0.567 and 300 cGy/min). These data demonstrate that a clinically relevant heat dose enhances very low dose rate, as well as high dose rate, ionizing radiation, but suggest that little benefit is to be gained from using dose rates intermediate between conventional radiotherapeutic high dose rates or dose rates representative of interstitial implants.     

Hepatic lipids in Reye-Johnson syndrome and in acute encephalopathy without fatty liver

The relationship between Reye-Johnson syndrome and acute encephalopathy without fatty liver was investigated by comparing the lipid composition of liver samples obtained from five patients with Reye-Johnson syndrome, two patients with acute encephalopathy, and five controls. The mean total hepatic triglyceride concentration was increased nearly sevenfold in Reye-Johnson syndrome and slightly decreased in acute encephalopathy when compared with the mean control value. The mean total hepatic free fatty acid concentration was increased nearly threefold in acute encephalopathy when compared with the mean value in Reye-Johnson syndrome. Total phospholipid content was decreased in the liver in Reye-Johnson syndrome, and this difference was caused mainly by a diminution of the hepatic lecithin fraction. The ratio of palmitic acid to oleic acid and hepatic free fatty acids was 2.5 in Reye-Johnson syndrome, 0.7 in acute encephalopathy, and 0.8 in controls. These results suggest that, despite clinical similarities and laboratory evidence of hepatic dysfunction in both Reye-Johnson syndrome and acute encephalopathy, different pathogenic mechanisms may be responsible for the liver abnormalities found in the two syndromes.     

Colonoscopy in the management of diseases of the colon and rectum

This report covers a 2.5-year experience with colonoscopy in the management of 208 patients (104 men and 98 women, average age 58 years). Colonic bleeding of unknown cause and abnormal barium-enema findings were the most common indications for colonoscopic examination. During this period, 110 colonoscopic polypectomies were performed. Among the few complications was one case of perforation of the sigmoid from transcolonoscopic removal of a small carcinoma; the perforation was incidentally discovered at the time of subsequent laparotomy. Bleeding occurred in 6 patients, but only one of them required surgical intervention to arrest the hemorrhage. Colonoscopy is a safe, effective and reliable diagnostic and therapeutic procedure. Its use can reduce expense for the patient and obviate a long painful postoperative period.     

Blastogenic response of human lymphocytes to oral bacterial antigens: characterization of bacterial sonicates

Soluble sonicate supernatant preparations were made from Actinomyces viscosus (ATCC 19246), A. naeslundii (ATCC 12104), two strains of Veillonella alcalescens (strain HV-1 and a human oral isolate), Streptococcus sanguis (ATCC 10556), S. mutans (strain 6715-T2), Bacteroides melaninogenicus (strain K110), and Leptotrichia buccalis (isolated from human dental plaque). These supernatants were characterized with reference to their chemical and antigenic components and their biological activity determined by using in vitro lymphocyte blastogenesis as a measure of the host's cellular immune response. The sonicate supernatant of each bacterium contained protein, neutral sugars, methylpentose, and nucleic acids. Protein was the major component in all except L. buccalis, in which neutral sugars predominated. The antigenic components in each supernatant were detected by using rabbit antisera prepared against the whole bacteria and the sonicate supernatant. The supernatants showed a complex antigenic distribution on immunoelectrophoretic analysis. The supernatants were shown to be antigenic and not mitogenic in nature, since neither cord blood lymphocytes nor all adult lymphocytes were stimulated. The supernatant antigen preparations showed a reproducible, dose-dependent, and kinetic response in vitro, which was similar to that seen with the antigen preparation streptokinase-streptodornase.