Biomedical subjects
E G Brown
Publications and source records attributed to E G Brown.
Interference is controlled by segment 2 and possibly by segment 8 of the nondefective interfering influenza virus variant A/FM/1/47-MA.
On mouse adaption of A/FM/1/47, a variant, A/FM/1/47-MA (FM-MA), that had acquired the properties of increased virulence and interference was produced. Coinfection of cells with FM-MA and prototype strains of influenza virus yielded > 100-fold more FM-MA virus than prototype virus, whereas coinfection with the same prototype strains and the parental A/FM/1/47 virus produced equivalent yields, indicating that FM-MA had acquired mutations that confer the property of interference during mouse adaption. FM-MA is a nondefective interfering virus that grows to a high titer in vivo and in vitro. It has previously been shown that segments 4, 7, and 8 and possibly segment 5 account for the increased virulence. In this study we show by genetic analysis of FM-MA x A/HK/1/68 reassortants that segment 2, coding for the polymerase-associated protein PB1, and possibly segment 8, encoding the NS1 and NS2 proteins, control the ability of FM-MA to interfere. Interference could not be overcome by increasing the titer of the coinfecting strain, but delaying FM-MA infection by 4 to 6 h did avoid interference. During interference of A/HK/1/68, protein synthesis was inhibited by less than 65% throughout coinfection. Given the kinetics of interference and the small perturbation in protein synthesis, interference appeared to occur at the level of late genome replication or virus assembly. Virulence and interference in FM-MA were not linked. An interfering avirulent FM-MA x A/HK/1/68 reassortant, E07, was capable of protecting mice against lethal pneumonia due to a virulent noninterfering reassortant, H04.
Biosynthesis of the tropane-related cyanobacterial toxin anatoxin-a: role of ornithine decarboxylase.
A study was made of the biosynthesis by Anabaena flos-aquae of the tropane-related alkaloid anatoxin-a. Evidence is presented that the toxin arises from ornithine via putrescine (1,4-diaminobutane) and that ornithine decarboxylase (EC 4.1.1.17) is involved. An ornithine decarboxylase preparation, with optimal activity at pH 8, was obtained from Anabaena flos-aquae and partially purified by gel-filtration chromatography on DEAE-cellulose. One major and one minor peak of enzymic activity were obtained with Km values of 1.25 and 2.5 mM, respectively. Plasmid DNA (10 Kb; Mr 6.5 x 10(6] was detected in the toxic strain of Anabaena flos-aquae but not in a non-toxic strain. DNA from the toxin-producing strain of Anabaena flos-aquae transforms the non-toxic into a toxic strain.
Effects of benzimidazole on the purine and pyrimidine metabolism of yeast.
Yeast cells inhibited by benzimidazole accumulate hypoxanthine with associated efflux of xanthine. Unlike control cells, inhibited cells contain no detectable free UMP and CMP. Benzimidazole decreases uptake of [8-14C]hypoxanthine into the intracellular pool of hypoxanthine and xanthine but causes radioactive xanthine to accumulate in the medium. In inhibited cultures there is a threefold increase in incorporation of [8-14C]hypoxanthine into the total (intracellular plus extracellular) xanthine. Uptake of [8-14C]hypoxanthine into free nucleotides and into bound adenine and guanine was inhibited by 70%. Uptake of [U-14C]glycine into IMP, AMP, GMP, DNA and RNA was also substantially decreased. Incorporation of [2-14C]uracil into the intracellular uracil pool was inhibited by 30% and into free uridine and cytidine by over 90%. Benzimidazole inhibited incorporation of [8-3H]IMP into AMP and GMP, and decreased substantially the activity of glutamine-amidophosphoribosyltransferase (EC 2.4.2.14). Yeast cultures were shown to N-ribotylate benzimidazole. Results are consistent with benzimidazole inhibiting yeast growth by competing for P-rib-PP and so depriving other ribotylation processes such as the 'salvage' pathways and de novo synthesis of purines and pyrimidines.
Comparative analyses of vesiculovirus proteins utilizing partial cleavage fragments at tryptophan residues.
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The inactivation of viruses in cattle and pig slurry by aeration or treatment with calcium hydroxide.
Porcine enterovirus type 2 or porcine adenovirus type 3 were seeded into samples of pig slurry, and a bovine enterovirus was seeded into cattle slurry, and samples of the slurry were aerated in the laboratory for 21 days. The viruses were inactivated more rapidly in the aerated slurry than in control slurry which was not aerated. The difference in inactivation rate was greatest for the porcine adenovirus and least for the bovine enterovirus. Inactivation of the porcine enterovirus in aerated distilled water and in aerated, autoclaved pig slurry proceeded at a similar rate as in the same materials which were not aerated. Ten samples of aerated slurry were collected from an aeration tank which received weekly additions of raw pig slurry which was sampled at the same times. Each sample yielded a porcine enterovirus after concentration with the polyelectrolyte PE-60, but in three comparative titrations the viral infectivity titre in concentrates of the raw slurry was at least 1000 times greater than in the aerated slurry. Porcine enterovirus type 2 and porcine adenovirus type 3, which were seeded into pig slurry, and a bovine enterovirus seeded into cattle slurry, were inactivated by treatment of the slurry with calcium hydroxide at pH 11.5. The inactivation rate was highest for the bovine enterovirus and lowest for the porcine adenovirus.
Analysis by high-pressure liquid chromatography of the free nucleotide pools of rat tissues [proceedings].
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Thoracic transillumination: aid in the diagnosis and treatment of pneumopericardium.
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Preventing necrotizing enterocolitis in neonates.
Necrotizing enterocolitis of newborn infants virtually vanished from our nurseries during the four years since the introduction of a slowly progressive feeding regimen. This cautions approach to feeding has been applied to selected infants whose condition during labor and delivery or whose neonatal problems indicate that they are at risk.
Isolation of animal viruses from farm livestock waste, soil and water.
Ten porcine enteroviruses, 2 porcine adenoviruses and 1 coronavirus were isolated directly from 32 samples of slurry collected from a pig fattening house. Concentration of the same samples by adsorption with the polyelectrolyte PE-60 yielded 24 porcine enteroviruses and 3 porcine adenoviruses. A porcine enterovirus was isolated, following PE-60 concentration, from 1 to 6 slurry samples from a sow farrowing house. No virus was isolated from 12 samples of slurry from dairy cows nor from 6 slurry samples from a calf-rearing unit. A porcine enterovirus was isolated from soil samples, after concentration with PE-60, collected 1, 2 and 8 days after pig slurry was spread on hay stubble. Two porcine enteroviruses were isolated by membrane filtration from 26 samples of surface run-off from land on which pig slurry was routinely spread, and 2 bovine enteroviruses were isolated from cattle feedlot run-off after adsorption to layers of talc and celite followed by hydroextraction. A porcine enterovirus was also isolated from 1 of 33 samples of surface water collected on farms on which pig slurry was routinely spread on the land, but no virus was isolated from 36 samples of ground water from the same farms. The surface water and ground water samples were concentrated by talc-celite adsorption and hydroextraction.
Isolation of an adenosine 3':5'-cyclic monophosphate-binding protein from tissues of higher plants [proceedings].
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Biosynthesis of the pyrimidinyl amino acid lathyrine by Lathyrus tingitanus L.
The biosynthesis of the pyrimidinyl amino acid lathyrine by seedlings of Lathyrus tingitanus L. was shown to be stimulated by uracil. [6(-14)C]Orotate, [2(-14)C]uracil and [3(-14)C]serine were incorporated into lathyrine; the incorporation of [6(-14)C]orotate was substantially decreased in the presence of uracil. Chemical degradation to locate the 14C incorporated from labelled precursors showed that 90% of the radioactivity incorporated into lathyrine from [3(-14)C]serine could be recovered in the alanine side chain. Over 80% of the radioactivity incorporated from [2(-14)C]uracil was shown to be located in C-2 of lathyrine. It is concluded that under the conditions studied, lathyrine arises from a preformed pyrimidine arising via the orotate pathway. Paradoxically, it was also possible to confirm previous reports that radioactivity from L-[guanidino-14C]homoarginine is incorporated into lathyrine and gamma-hydroxyhomoarginine. However, as homoarginine and gamma-hydroxyhomoarginine are also both labelled by [2(-14)C]uracil, it is suggested that they are products of the ring-opening of lathyrine and that reversibility of this process accounts, at least in part, for their observed experimental incorporation into lathyrine.
Cyclic nucleotide phosphodiesterase from Spinacea oleracea L: subcellular distribution and properties [proceedings].
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Adenylate cyclase activity in higher plants [proceedings].
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A paper chromatoelectrophoresis method for the determination of bilirubin binding to serum protein.
A technique is described in which paper chromatoelectrophoresis is used to measure the bilirubin binding capacity of albumin in serum. It is equivalent to the Sephadex G-25 method and its results are highly reproducible. From a single pool of serum, multiple determinations indicated the mean bilirubin binding capacity to be 23.7 +/- 0.76 (SD) mg/dl and the greatest difference between any two values was 2 mg/dl. This new technique can determine the bilirubin binding capacity of a serum sample in 15 min. Highly skilled technicians are not needed and very small quantities of serum are required, which gives it a definite advantage over the Sephadex G-25 method.
Challenges "fact" cited Committee report.
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Development of a minature pCO2 electrode for biomedical applications.
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Blood volume and blood pressure in infants with respiratory distress.
Mean aortic blood pressure volume were measured in true premature infants with respiratory distress syndrome. Seven infants had Type I RDS (hyaline membrane disease) and ten had transient tachypnea of the newborn (Type II RDS). Blood volume in the infants with Type I RDS was significantly lower than in the infants with Type II RDS. The difference was due to a low red cell volume. Mean aortic blood pressure was within the range of normal in all infants and therefore did not reflect the low blood volume of infants with Type I RDS. Normal mean aortic blood pressure does not indicate normal blood volume or normal circulation in infants with RDS.