The presence of free infectious cytomegalovirus (CMV) in the plasma of donated CMV-seropositive blood and platelets.

An in vitro study was carried out to determine the presence of free infectious CMV in the supernatant of donated units of blood and platelets which were known to be CMV seropositive. One sample was taken from each of 10 units of CMV-seropositive platelet donations which were 4 days old. Ten units of seropositive blood were sampled at intervals over their storage lifespan. Each sample was divided into two and thrombin was added to one of them. The samples were all prepared by centrifugation. The resulting supernatant from the clotted samples was used in in vitro culture studies using the MRC-5 cell line to ascertain the infectivity of the samples. The anticoagulated supernatants were subjected to PCR analysis to detect the presence of free genomic CMV DNA. All of the units of blood and platelets tested positive for the presence of genomic CMV DNA by PCR. Seven out of the 10 units of blood were culture positive from samples taken 3-4 weeks into their shelf-life. None of the platelet samples was culture positive. The cultures of supernatants taken from seropositive blood were negative when the units were fresh, but further into their storage life, the cultures became positive, indicating that infectious material was released into the supernatant during storage, presumably due to the breakdown of intact white cells.

Evaluation of the Pall RC100 leucocyte removal filters and the effect of air introduction on its performance.

We evaluated the efficiency of Pall RC100 leucocyte removal filters in processing two units of concentrated red cells for transfusion. Our results show that the filter is very effective in processing the first unit. However, 32% (5/16) of the filters evaluated allowed a leak of substantial numbers of white cells towards the end of the transfusion of the second unit of blood. Air introduction experiments showed that as little as 2 ml of air in the filter may cause major deterioration of the filter function.

A new method to study the efficiency of third generation blood filters.

In order to study the efficiency of third generation blood filters we have devised a new method using 3 microns pore size polycarbonate filter membranes and a filtration chamber to trap leucocytes passing through the blood filter. The method has enabled us to make two important observations: (1) The filters function very efficiently at the start but the efficiency diminishes progressively with time. (2) When the blood flow through the filter is retarded, due to defective priming and/or filter malfunction, the filters fail even at the outset of the transfusion.

New nonpeptide angiotensin II receptor antagonists. 2. Synthesis, biological properties, and structure-activity relationships of 2-alkyl-4-(biphenylylmethoxy)quinoline derivatives.

A novel series of nonpeptidic angiotensin II (AII) receptor antagonists is reported, derived from linkage of the biphenylcarboxylic acid or biphenylyltetrazole moiety found in previously described antagonists via a methyleneoxy chain to the 4-position of a 2-alkyl quinoline. When evaluated in an in vitro binding assay using a guinea pig adrenal membrane preparation, compounds in this series generally gave IC50 values in the range 0.01-1 microM. Structure-activity studies showed the quinoline nitrogen atom and a short alkyl chain at the quinoline 2-position to be essential for receptor binding. On intravenous administration in a normotensive rat model, the more potent compounds inhibited the AII-induced pressor response with ED50 values in the range 0.1-2.0 mg/kg. One of the compounds, 2-ethyl-4-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methoxy]quinoline (5g), demonstrated good oral activity in two rat models. At doses in the range 1-10 mg/kg in AII-infused, normotensive rats, the compound exhibited a dose-related inhibition of the pressor response with a good duration of action at the higher doses. In a renal hypertensive rat model, compound 5g showed a rapid and sustained lowering of blood pressure at a dose of 5 mg/kg. On the basis of its profile, this compound, designated ICI D8731, has been selected for clinical evaluation.

Anomalous fluorescence properties of 4-N,N-dimethylaminobenzoic acid in polar solvents.

4-N,N-Dimethylaminobenzoic acid exhibits anomalous fluorescence in polar and hydrogen-bonding solvents. The fluorescence spectra and kinetics suggest that this arises due to the formation of a ground-state dimer or higher polymer. Preliminary measurements in hexane containing small amounts of polar acetonitrile do not rule out the possibility of exciplex formation also occurring.

Genetic evidence that the putative receptor binding domain of apolipoprotein B (residues 3130 to 3630) is not the only region of the protein involved in interaction with the low density lipoprotein receptor.

We have searched for sequence differences in the region of the apolipoprotein B (apo B) gene encoding amino acids 3130-3630 in eight individuals with reduced affinity of low density lipoprotein (LDL) for the normal LDL-receptor. All individuals were hypercholesterolaemic and were selected either on the basis of reduced fractional catabolic rate (FCR) of autologous LDL or substantially reduced binding of their LDL to normal LDL-receptors determined by an in vitro cell growth assay using the U937 macrophage-like cell line. Segments of the apo B gene were amplified by the polymerase chain reaction. Using a combination of cloning and sequencing the amplified fragment, together with chemical cleavage mismatch analysis, no sequence differences were identified in this region of the gene. We therefore conclude that variation outside the region of the apo B gene that codes for amino acids 3130-3630 must be responsible for the reduced LDL clearance in these patients.

1,2,4-Triazolo[4,3-a]pyrazine derivatives with human renin inhibitory activity. 1. Synthesis and biological properties of alkyl alcohol and statine derivatives.

A series of 1,2,4-triazolo[4,3-a]pyrazine derivatives with human renin inhibitory activity, which incorporate (1S,2S)-2-amino-1,3-dicyclohexyl-1-hydroxypropane, statine (Sta), and (3S,4S)-4-amino-5-cyclohexyl-3-hydroxy-pentanoic acid (ACHPA) transition-state mimetics, have been prepared. Structure-activity relationships for renin inhibitory activity in the series are consistent with the 2-[8-isobutyl-6-phenyl-1,2,4-triazolo[4,3-a]pyrazin-3-yl]-3-(3 pyridyl)propionic acid moiety 10b acting as a non-peptidic replacement for the P4-P2 (Pro-Phe-His) residues of the natural substrate angiotensinogen. Compounds 12m, 12o and 12q were potent inhibitors of partially purified human renin (IC50 values 1.7, 6.8, and 3.7 nM, respectively), and also effectively lowered blood pressure in anesthetized, sodium depleted marmosets following intravenous administration. On oral administration however, no blood pressure lowering activity could be detected, and absorption studies in bile duct cannulated rats indicate that this may be due primarily to poor oral absorption, rather than rapid biliary excretion. The reason for the observed poor oral activity is not clear, but it seems unlikely that poor aqueous solubility or metabolic instability to gut enzymes are rate-determining, and other factors such as high molecular weight may also be very important.

The fractional catabolic rate of low density lipoprotein in normal individuals is influenced by variation in the apolipoprotein B gene: a preliminary study.

In a random sample of 22 normolipidaemic male Caucasian individuals, 35-49 years old, homozygosity for the X2 allele (cutting site) of the XbaI RFLP of the apo B gene was associated with higher mean total cholesterol and LDL-cholesterol concentration. These individuals also had significantly lower LDL fractional catabolic rate (P less than 0.03) and a lower degradation of LDL by mononuclear cells in vitro. We propose that the XbaI polymorphism is associated with amino acid changes in the apo B protein which influences LDL binding to the LDL-receptor. This modulates catabolism of this lipoprotein and so contributes to variability of plasma cholesterol levels.

Metabolic study of variation in plasma cholesterol level in normal men.

Variation in plasma cholesterol in normal populations underlies a 2-5 fold range of risk of coronary heart disease. The metabolic basis of this variation was studied in a healthy population recruited from a general-practice list. Compared with men in the modal decile of plasma cholesterol, those in the top decile maintained their high levels by overproduction of low-density lipoprotein (LDL). Men in the bottom decile of plasma cholesterol had low levels of LDL, resulting chiefly from a greater rate of fractional catabolism of this lipoprotein; and blood mononuclear cells from men in the bottom decile catabolised LDL more rapidly in vitro than did cells from other men. Intake of dietary lipids by men in the top, modal, and bottom deciles did not differ significantly. Different mechanisms appear to underlie high and low levels of plasma cholesterol in a normal population.