N-3,5 '-cycloxanthosine, the first natural occurrence of a cyclonucleoside

An Eryus sp. of marine sponge from the Great Australian Bight has yielded the first reported natural occurrence of a cyclonucleoside, N-3,5'-cycloxanthosine. The structure of N-3,5'-cycloxanthosine was confirmed by detailed spectroscopic analysis and total synthesis.

Effect of nutrition level and diets on creatinine excretion by sheep

In this experiment, creatinine (C) excretion by sheep was measured when they were fed different diets at different levels of intake. Creatinine excretion was not affected by the level of feed intake or the addition of salt to lucerne-based diets. However, differences between individual animals were significant. Creatinine excretion was significantly affected by diets, which were formulated by combining different amounts of lucerne chaff, oaten chaff and sorghum. It was also found that there were significant diurnal changes in the ratios of purine derivatives to creatinine (PD:C) in 3 hourly urine samples when the animals were fed either once or twice daily, but the average value for the PD:C ratio of any two urine samples taken 12 h apart was close to the daily mean. The results of this experiment suggest that if separate determination of the creatinine excretion by individual animals is made and the average value of the ratio of PD:C in two spot urine samples taken 12 h apart is used to predict PD excretion by spot urine sampling, microbial nitrogen flow can be estimated more accurately than when a fixed value of creatinine excretion is used for all animals and only a single urine sample is taken. (c) 2005 Elsevier B.V. All rights reserved.

The effect of different levels of dietary crude protein on urea metabolism of rusa deer (Cervus timorensis)

Two experiments were conducted to measure urea recycling and rumen flow dynamics in young rusa deer fed low (LP) or high (HP) protein diets. Pool size and flux rate of labelled urea. into and out of the blood pool were measured using single intravenous (i.v.) injection solutions containing [C-14] - and [N-15]-urea. A curve peeling technique was used to fit the enrichment of N-15 or specific radioactivity (SRA) of C-14 to exponential equations. Body urea-N pool size was significantly greater (P < 0.05) when a HP, compared to a LP diet, was fed. Urea space, expressed as a percent of live weight, total flux rate of urea through the blood pool and the irreversible loss of urea was similar for both diets. The mean (+/- S.E.M.) concentration of plasma urea-N was greater when animals were fed the HP diet compared to the LP diet (2 1.1 +/- 0.3 versus 14.4 +/- 1.4 mg/100 ml, respectively). Voluntary feed intake and digestibility of dietary components were also measured. Daily dry matter intakes were not affected by the crude protein (CP) content of the diet, although apparent DM digestibility was significantly greater for HP diet fed in both experiments. An intraruminal infusion of CrEDTA was used to determine rumen flow dynamics. Ruminal mean retention time, relative net outflow rate of water and passage rate constant (k(w)) were significantly greater (P < 0.05) when the HP diet was fed compared to the LP diet. The extent of urea metabolism and flux rates of urea between the blood and secondary pools appear similar to those previously reported for other ruminants fed diets contrasting in CP content. (c) 2005 Elsevier B.V. All rights reserved.

1,3-Dimethylisoguanine

The structure of 1,3-dimethylisoguanine [ or 6-amino-1,3-dimethyl-1H-purin- 2(3H)- one], C7H9N5O, has been redetermined and the correct assignment of H atoms on the heterocycle is now reported. Intermolecular hydrogen-bonding interactions confirm that this form is the correct molecular structure; this form is also in agreement with an earlier reported structure of the trihydrate form.

Prevalence of drug-resistance mutations and non-subtype B strains among HIV-infected infants from New York State

Summary: Prevalence studies indicate that transmission of drug-resistant HIV has been rising in the adult population, but data from the perinatally infected pediatric population are limited. In this retrospective study, we sequenced the pol region of HIV from perinatally infected infants diagnosed in New York State in 2001-2002. Analyses of drug resistance, subtype diversity, and perinatal antiretroviral exposure were conducted, and the results were compared with those from a previous study of HIV-infected infants identified in 1998-1999. Eight of 42 infants (19.1%) had provirus carrying at least 1 drug-resistance mutation, an increase of 58% over the 1998-1999 results. Mutations conferring resistance to nucleoside reverse transcriptase inhibitors, nonnucleoside reverse transcriptase inhibitors, and protease inhibitors were detected in 7.1%, 11.9%, and 2.4% of specimens, respectively. Consistent with previous results, perinatal antiretroviral exposure was not associated with drug resistance (P = 0.70). Phylogenetic analysis indicated that 16.7% of infants were infected with a non-subtype B strain of HIV. It seems that drug-resistant and non-subtype B strains of HIV are becoming increasingly common in the perinatally infected population. Our results highlight the value of resistance testing for all HIV-infected infants upon diagnosis and the need to consider subtype diversity in diagnostic and treatment strategies.