Identification of an epitope on the P and V proteins of simian virus 5 that distinguishes between two isolates with different biological characteristics

Two canine isolates of simian virus 5 (SV5), termed CPI+ and CPI-, were examined for their ability to react with a bank of monoclonal antibodies (MAbs) that had been previously raised against a human isolate of SV5. CPI- virus was originally isolated from the brain of a gnotobiotic dog infected with CPI+ virus and establishes persistent infections more readily than CPI+ in vitro. Of more than 50 MAbs tested, only one (P-k) reacted with CPI+ but not CPI-, enabling distinction between the two canine isolates. It had been shown previously that MAb P-k reacts with an epitope common to both the P and V proteins. In order to characterize further the epitope binding site of this MAb the P/V genes of CPI+ and CPI- were sequenced. There were four nucleotide differences between CPI+ and CPI-, three of which resulted in predicted amino acid substitutions. Synthetic peptides corresponding to regions encompassing these changes were made and radioimmune competition assays were used to identify the epitope binding site of MAb P-k. Sequence comparison of the P/V gene of CPI+ with the published sequence of a monkey isolate of SV5 (W3) revealed 14 nucleotide differences with five amino acid substitutions. The only amino acid substitution observed between CPI+, CPI- and W3 which altered the predicted secondary structures of the P and V proteins was a leucine to proline change that induced a predicted beta-turn and resulted in the loss of binding of MAb P-k.

Structural requirements for the modulatory effect of 6-substituted pterins on interleukin 2 receptor binding

(6R)-5,6,7,8-Tetrahydrobiopterin is produced by stimulated human T lymphocytes, and is known to affect various aspects of interleukin-2-directed T cell proliferation. Using an increased apparent affinity of interleukin 2 receptor to interleukin 2 as a measure of activity, this study explores whether other 6-substituted pterins might have the same effect, and what structural features are necessary for activity. Of the compounds tested, only the T-lymphocyte-derived (6R)-5,6,7,8-tetrahydrobiopterin was active. The diastereomeric (6S)-5,6,7,8-tetrahydrobiopterin was inactive, as were 7,8-dihydrobiopterin, sepiapterin, 5,6,7,8-tetrahydroneopterin, 6,7-dimethyl-5,6,7,8-tetrahydropterin and 6-hydroxymethylpterin. 7,8-Dihydroneopterin and neopterin were also found to be inactive. It follows that neither of these compounds participates in the feedback modulation of IL-2 receptor affinity, although both of them can be detected upon IFN-gamma stimulation of human monocytes/macrophages. A computer-based molecular modelling study of (6R)-5,6,7,8-tetrahydrobiopterin and (6R)-5,6,7,8-tetrahydroneopterin revealed substantial differences in overall shape between the two molecules, with certain features figuring prominently in the low-energy conformers of (6R)-5,6,7,8-tetrahydrobiopterin.

Modulation of interleukin 2 high affinity binding to human T cells by a pyrimidodiazepine insect metabolite

An insect metabolite containing the little known pyrimido[4,5-b][1,4]diazepine ring system has been found to act as an effective mimic of tetrahydrobiopterin in its ability to modulate the affinity of interleukin 2 (IL-2) for its receptors on human T cells. Semi-empirical molecular orbital calculations reveal that while tetrahydrobiopterin has considerable flexibility, the pyrimidodiazepine has rather few conformational options and offers a useful model for exploring the nature of the pterin binding site.

Osteoporotic fracture admissions compared to other major medical admissions in Irish public hospitals

Multinational reports suggest Ireland has one of the greatest illness burdens related to osteoporosis. Hospital care represents the costliest portion of health services. We found public hospital bed days for fragility fractures in Ireland increased by 43% between 2008 and 2017 which exceeded those for other common diseases.

INTRODUCTION

Recent multinational reports suggest Ireland has one of the greatest illness burdens related to osteoporosis, manifesting clinically as fragility fractures (FF). International reports show that FF incidence, rate of hospital admission and cost are similar or greater than those for breast cancer, myocardial infarction and stroke. Studies addressing the illness burden of osteoporosis in Ireland are few, and none compares fragility fractures to other common chronic diseases.

METHODS

A retrospective analysis of national administrative data for all public hospital admissions was performed on adults aged 50 years and older from January 2008 to December 2017.

RESULTS

In 2017, public hospital bed days for FF totalled 249,887 outnumbering Chronic Obstructive Pulmonary Disease (COPD): 131,897; 6 solid cancers (CA): 118,098; myocardial infarction (MI): 83,477; and diabetes mellitus (DM): 31,044. Bed days for FF increased by 43% between 2008 and 2017, in contrast to a 32%, 28% and 31% reduction for CA, MI and DM, respectively, and a 12% increase for COPD. Public hospital bed days for FF in 2016 were greater than MI, stroke, atrial fibrillation and chest pain combined but less than a combination of COPD, pneumonia and lower respiratory tract infection.

CONCLUSION

Osteoporotic fractures represent a large and rapidly increasing illness burden amongst older Irish adults, with substantial care requirements and the resulting onus on our healthcare system. Urgent action is needed to address this public health issue and the services for those at risk of fracture.