In vitro activation of human herpesviruses 6 and 7 from latency

Human herpesviruses 6 and 7 (HHV-6 and HHV-7) are prevalent lymphotropic viruses that infect more than 80% of children at infancy or during early childhood. Infection ranges from asymptomatic to severe disease. HHV-6B causes exanthem subitum. The virus can be recovered from peripheral blood mononuclear cells during the acute phase of exanthem subitum, but the host remains latently infected throughout life. In immunocompromised patients undergoing kidney, liver, or bone marrow transplantation latent HHV-6B is reactivated, at times causing severe or fatal disease. Here, we describe the establishment of an in vitro system for reactivation of HHV-6B and HHV-7 from latency. HHV-7 is reactivated from latently infected peripheral blood mononuclear cells by T-cell activation. HHV-6B could not be reactivated under similar conditions; however, the latent HHV-6B could be recovered after the cells were infected with HHV-7. Once reactivated, the HHV-6B genomes became prominent and the HHV-7 disappeared. We conclude that HHV-7 can provide a transacting function(s) mediating HHV-6 reactivating from latency. Understanding the activation process is critical for the development of treatments to control the activation of latent viruses so as to avoid these sometimes life threatening infections in transplant recipients.     

The fate of a thiazolidinedione antidiabetic agent in rat and dog

1. The fate of [14C]BRL 49653C, a novel thiazolidinedione antidiabetic agent, has been studied following oral administration to the rat and dog. 2. Clearance was almost exclusively by metabolism, with only small amounts of unchanged BRL 49653 being excreted by either species. 3. Phase I metabolism resulted in ring hydroxylation, N-demethylation and oxidative removal of the pyridinylamino function to yield a phenoxyacetic acid derivative. 4. Sulphation of phase I metabolites occurred in both species, but glucuronidation was only observed in the rat. 5. The parent compound was the major circulating component in both species at early times, but at later times sulphate conjugates of phase 1 metabolites were predominant.     

The versatile and esthetic metal-ceramic crown

The predictability, many advantages and remarkable adaptability of metal-ceramic crowns account for their frequent use. Metal-ceramic crowns will continue to be one of the most widely used dental restorations.     

Glucose-induced changes in renal haemodynamics in proteinuric type 1 (insulin-dependent) diabetic patients: inhibition by acetylsalicilic acid infusion

The effect of hyperglycaemia on renal function in diabetic nephropathy remains poorly understood. We investigated the renal haemodynamic response to an acute plasma glucose rise from sustained euglycaemia to sustained hyperglycaemia in eight persistently proteinuric Type 1 (insulin-dependent) diabetic patients. Studies were performed in a double-blind cross-over manner after i.v. injection of 450 mg lysine acetylsalicilate (equivalent to 250 mg acetylsalicilic acid) or equal volume of 0.9% NaCl (isotonic saline). In the isotonic saline experiments hyperglycaemia produced a significant rise, by approximately 35%, in glomerular filtration rate in all patients from 41.5 +/- 5.2 to 55 +/- 6 ml.min-1.1.73 m-2 (p < 0.005) and an increase in sodium paraminohippurate clearance from 178 +/- 22.7 to 220 +/- 20.0 ml.min-1.1.73 m-2 (p < 0.05). These changes took place within the first 30 min of glucose infusion and were maintained for a 90 min hyperglycaemic period. Filtration fraction did not change significantly. Infusion of lysine acetylsalicilate lowered baseline glomerular filtration rate (isotonic saline vs lysine acetylsalicilate 41.5 +/- 5.2 vs 30.0 +/- 5.7 ml.min-1.1.73 m-2; p < 0.05) and significantly blunted the rise in glomerular filtration rate during hyperglycaemia (glomerular filtration rate increment: saline vs lysine acetylsalicilate: 13.6 +/- 2.8 vs 5.3 +/- 1.8 ml.min-1.1.73 m-2; p < 0.005). The effects on renal plasma flow were similarly blunted. In five additional patients, time- and volume-controlled isotonic saline experiments during sustained euglycaemia showed no significant changes in glomerular filtration rate and sodium paraminohippurate clearance.(ABSTRACT TRUNCATED AT 250 WORDS)     

Delineation of flow-limiting segment and predicted airway resistance by movable catheter

Using intrabronchial lateral pressure catheters, we determined the precise location and movement of the flow-limiting segment (FLS) in excised dog and human lungs; under maximal flow conditions, profiles of resistance and transmural pressure from the "mouth" to segmental bronchi were also obtained. In the same lungs, using the interrupter technique, IVFP curves were constructed; with these curves and lung compliance, the relationship between Vmax and Pel was studied using the analysis of Pride et al. The FLS consisted of well-demarcated short lengths (2-3 cm) of the trachea at large lung volumes which moved to lobar or semental bronchi at small volumes (10-20% TLC). These relationships, coupled with observations of the movement of the equal pressure point (EPP), support the idea that in the excised lung the location of the FLS is determined by both the location of the EPP and the compliance of the downstream airway wall; thus FLS MAY NOT FOLLOW UPSTREAM MOVEMENTS OF EPP until EPP reaches a more compliant segment of the bronchial tree (lobar and proximal segmental bronchi). Upstream resistance (Rs) and transmural pressure of collapse (Ptm') calculated indirectly from the slope and intercept of the Vmax vs. Pel relationship accurately predicted values of resistance and transmural pressure measured directly in the same lungs at a point just upstream to FLS.     

The role of attention in a spatial memory task in Alzheimer disease patients

Memory and attention are interrelated cognitive processes that most likely influence the functioning of each other, yet they are often difficult to distinguish in psychological experiments. Young, aged adults, and patients with Alzheimer disease (AD) were tested on a delay response task measuring spatial memory that also placed high demands on attentional resources. Aged adults performed as well as young, suggesting that neither attentional nor memory abilities were exceeded in either group. However, AD subjects were severely impaired on this task. Two further experiments with AD patients examined the relative contribution of attentional and memory deficits in the performance of this population. Both memory and attentional impairments were found; however, errors due to memory factors were more closely related to severity of disease as measured on the Folstein Mini-Mental State Examination than were errors of attentional origin. These studies demonstrate the necessity of accounting for attentional components in studies examining memory, especially in patients with AD.     

Ion composition of airway surface liquid of patients with cystic fibrosis as compared with normal and disease-control subjects

To test whether a major contribution of airways epithelial ion transport to lung defense reflects the regulation of airway surface liquid (ASL) ionic composition, we measured ASL composition using the filter paper technique. On nasal surfaces, the Cl- concentration (approximately 125 meq/liter) was similar to plasma, but the Na+ concentration (approximately 110 meq/liter) was below plasma, and K+ concentration (approximately 30 meq/liter) above plasma. The resting ASL osmolarity [2(Na+ + K+); 277 meq/liter] approximated isotonicity. There were no detectable differences between cystic fibrosis (CF) and normal subjects. In the lower airways, the Na+ concentrations were 80-85 meq/liter, K+ levels approximately 15 meq/liter, and Cl- concentrations 75-80 meq/liter. Measurements of Na+ activity with Na(+)-selective electrodes and osmolality with freezing point depression yielded values consistent with the monovalent cation measurements. Like the nasal surfaces, no differences in cations were detected between CF, normal, or chronic bronchitis subjects. The tracheobronchial ASL hypotonicity was hypothesized to reflect collection-induced gland secretion, a speculation consistent with observations in which induction of nasal gland secretion produced hypotonic secretions. We conclude that there are no significant differences in ASL ion concentrations between CF, normal, and chronic bronchitis subjects and, because ASL ion concentrations exceed values consistent with defensin activity, the failure of CF lung defense may reflect predominantly factors other than salt-dependent defensins.     

The solution structure of the complex of Lactobacillus casei dihydrofolate reductase with methotrexate

We have determined the three-dimensional solution structure of the complex of Lactobacillus casei dihydrofolate reductase (18.3 kDa, 162 amino acid residues) formed with the anticancer drug methotrexate using 2531 distance, 361 dihedral angle and 48 hydrogen bond restraints obtained from analysis of multidimensional NMR spectra. Simulated annealing calculations produced a family of 21 structures fully consistent with the constraints. The structure has four alpha-helices and eight beta-strands with two other regions, comprising residues 11 to 14 and 126 to 127, also interacting with each other in a beta-sheet manner. The methotrexate binding site is very well defined and the structure around its glutamate moiety was improved by including restraints reflecting the previously determined specific interactions between the glutamate alpha-carboxylate group with Arg57 and the gamma-carboxylate group with His28. The overall fold of the binary complex in solution is very similar to that observed in the X-ray studies of the ternary complex of L. casei dihydrofolate reductase formed with methotrexate and NADPH (the structures of the binary and ternary complexes have a root-mean-square difference over the backbone atoms of 0.97 A). Thus no major conformational change takes place when NADPH binds to the binary complex. In the binary complex, the loop comprising residues 9 to 23 which forms part of the active site has been shown to be in the "closed" conformation as defined by M. R. Sawaya & J. Kraut, who considered the corresponding loops in crystal structures of complexes of dihydrofolate reductases from several organisms. Thus the absence of the NADPH does not result in the "occluded" form of the loop as seen in crystal studies of some other dihydrofolate reductases in the absence of coenzyme. Some regions of the structure in the binary complex which form interaction sites for NADPH are less well defined than other regions. However, in general terms, the NADPH binding site appears to be essentially pre-formed in the binary complex. This may contribute to the tighter binding of coenzyme in the presence of methotrexate.