Aspects of early arthritis. What determines the evolution of early undifferentiated arthritis and rheumatoid arthritis? An update from the Norfolk Arthritis Register

Over 3500 patients with recent onset inflammatory polyarthritis (IP) have been recruited by the Norfolk Arthritis Register (NOAR) since 1990. Longitudinal data from this cohort have been used to examine the prevalence and predictors of remission, functional disability, radiological outcome, cardiovascular mortality and co-morbidity and the development of non-Hodgkin's lymphoma. Rheumatoid factor titre, high baseline C-reactive protein and high baseline HAQ score are all predictors of a poor outcome. There is a strong association between possession of the shared epitope and the development of erosions. Patients who satisfy the American College of Rheumatology criteria for rheumatoid arthritis (RA) have a worse prognosis than those who do not. However, it appears that these patients are a poorly defined subset of all those with IP rather than having an entirely separate disease entity. New statistical techniques offer exciting possibilities for using longitudinal datasets such as NOAR to explore the long-term effects of treatment in IP and RA.     

Estrogen regulates cytokine production and apoptosis in PMA-differentiated,macrophage-like U937 cells

We have investigated the effects of sex steroids, estradiol (E2), and testosterone (T) on the synthesis of tumor necrosis factor alpha (TNF-alpha) and interleukin-10 (IL-10) in phorbol-myristate-acetate (PMA)-differentiated human monoblastic U937 cells. The ability of both hormones to modulate the viability and programmed cell death of macrophage-like PMA-differentiated U937 cells was also inspected. E2 increased TNF-alpha synthesis, whereas T had no effect on the production of this cytokine. The combination of E2 and its antagonist tamoxifen or ICI-182,789 completely abolished the induction of TNF-alpha, while combination of T and its antagonist Casodex (CSDX) did not significantly affect TNF-alpha production by U937 cells. Exposure of cells to E2 resulted in a dose-dependent decrease of IL-10 synthesis, while again T did not show any detectable effect. In addition, E2 induced a significant increase of apoptosis in macrophage-like U937 cells and this increase was inhibited by the simultaneous addition of either tamoxifen or ICI-182. In contrast, T alone or in combination with CSDX did not modify apoptotic rates of U937 cells. This evidence, taken together, suggests that estrogens, but not androgens, exert a pro-inflammatory action through the modulation of TNF-alpha and IL-10, and regulate the immune effector cells by the induction of programmed cell death.     

Triatomines involved in domestic and wild Trypanosoma cruzi transmission in Concepción, Corrientes, Argentina

An entomological and serological survey was performed in three localities of the Department of Concepción, Province of Corrientes, Argentina in 1998 and 1999, to identify triatomines species involved in domestic and wild transmission of Chagas disease. Triatomines were collected by man/hour capture in 32 houses randomly selected and 44 nearby outdoor ecotopes. Trypanosoma cruzi infection in triatomines was assessed by direct microscopic observation (400x) of feces and polymerase chain reaction. Serological techniques used for people were Indirect Hemagglutination Test and Indirect Fluorescent Test. Triatomines were collected in 28.1% of the houses and 31.8% of the wild biotopes. Triatoma infestans (Klug 1834) was exclusively found indoors and T. cruzi infected 60% of them. Triatoma sordida (St?l 1859) was mainly found in extradomestic ecotopes where trypanosome infection rate reached 12.7%. Serological study of 98 local people showed that 29.6% were seroreactive; most of their houses were closed to wild biotopes colonized by T. sordida. Results indicate that there is an active T. infestans mediated transmission of Chagas disease in this zone that yields important human prevalence and that the populations of T. sordida in wild biotopes not only sustain the wild T. cruzi cycle but also represent an actual risk for people living in the area.     

Scaffolding functions of arrestin-2 revealed by crystal structure and mutagenesis

Arrestin binding to activated, phosphorylated G protein-coupled receptors (GPCRs) represents a critical step in regulation of light- and hormone-dependent signaling. Nonvisual arrestins, such as arrestin-2, interact with multiple proteins for the purpose of propagating and terminating signaling events. Using a combination of X-ray crystallography, molecular modeling, mutagenesis, and binding analysis, we reveal structural features of arrestin-2 that may enable simultaneous binding to phosphorylated receptor, SH3 domains, phosphoinositides, and beta-adaptin. The structure of full-length arrestin-2 thus provides a uniquely oriented scaffold for assembly of multiple, diverse molecules involved in GPCR signal transduction.     

Phylogeny of the Drosophila saltans species group based on combined analysis of nuclear and mitochondrial DNA sequences

Nucleotide sequences from two nuclear loci, alcohol dehydrogenase and internal transcribed spacer-1 of the nuclear ribosomal DNA repeats, and two mitochondrial genes, cytochrome oxidase I and cytochrome oxidase II, were determined from nine species in the Drosophila saltans species group. The partition homogeneity test and partitioned Bremer support were used to measure incongruence between phylogenetic hypotheses generated from individual partitions. Individual loci were generally congruent with each other and consistent with the previously proposed morphological hypothesis, although they differed in level of resolution. Since extreme conflict between partitions did not exist, the data were combined and analyzed simultaneously. The total evidence method gave a more resolved and highly supported phylogeny, as indicated by bootstrap proportions and decay indices, than did any of the individual analyses. The cordata and elliptica subgroups, considered to have diverged early in the history of the D. saltans group, were sister taxa to the remainder of the saltans group. The sturtevanti subgroup, represented by D. milleri and D. sturtevanti, occupies an intermediate position in this phylogeny. The saltans and parasaltans subgroups are sister clades and occupy the most recently derived portion of the phylogeny. As with previous morphological studies, phylogenetic relationships within the saltans subgroup were not satisfactorily resolved by the molecular data.      

A catalytic antioxidant metalloporphyrin blocks hydrogen peroxide-induced mitochondrial DNA damage

Reactive oxygen species (ROS) have been implicated as the cause of cumulative damage to DNA, proteins and lipids that can ultimately result in cell death. A common problem when measuring oxidative DNA damage has been the introduction of modifications in the native state of the molecule by many DNA isolation methods. We circumvented this problem by employing direct PCR (DPCR) of whole cell lysates. DPCR of mouse lung fibroblasts performed better than PCRs containing template acquired by phenol/chloroform extraction or a commercially available genomic DNA isolation kit. We investigated the direct use of whole cell preparations in the polymerase chain reaction (PCR) to detect hydrogen peroxide (H₂O₂)-mediated DNA damage. We observed a concentration-dependent decrease in amplification efficiency of a 4.3 kb mitochondrial (mt)DNA target in H₂O₂-treated mouse lung fibroblasts (MLFs). At low doses the efficiency of amplification returns to control levels over 24 h. We detected no change in amplification efficiency of a plasmid control containing our mtDNA target under any of the culture conditions employed in these studies. Treatment of MLFs with the catalytic antioxidant manganese(III) meso-tetrakis(4-benzoic acid)porphyrin (MnTBAP) attenuates the effects of H₂O₂ exposure. When quantitated with an external standard the use of DPCR in tandem with a PCR amplification efficiency assay provides a powerful approach to assess oxidative mtDNA damage.     

Oxidative DNA Damage and Activation of c-Jun N-Terminal Kinase Pathway in Fibroblasts from Patients with Hereditary Spastic Paraplegia

1.Hereditary spastic paraplegia (HSP) is a genetically heterogeneous group of neurodegenerative disorders affecting 1 in 10,000 individuals. The present study was aimed to elucidate the role played by reactive oxygen species (ROS) in the pathogenesis of this disease. 2. To address this question we used 7-11 passaged fibroblasts from HSP patients to measure the extent of DNA damage induced by H2O2 treatment and to evaluate the JNK phosphorylation level after hydrogen peroxide and serum stimuli. 3. The present study demonstrates that HSP cells compared to controls are more sensitive to DNA damages induced by H2O2 treatment, and that JNK phosphorylation levels are increased in HSP fibroblasts compared to controls after hydrogen peroxide and serum stimuli. These results suggest a ROS-mediated pathogenetic mechanism for this disease.     

Myocardial impairment in chronic hypoxia is abolished by short aeration episodes: involvement of K+ATP channels

In vivo exposure to chronic hypoxia is considered to be a cause of myocardial dysfunction, thereby representing a deleterious condition, but repeated aeration episodes may exert some cardioprotection. We investigated the possible role of ATP-sensitive potassium channels in these mechanisms. First, rats (n = 8/group) were exposed for 14 days to either chronic hypoxia (CH; 10% O(2)) or chronic hypoxia with one episode/day of 1-hr normoxic aeration (CH+A), with normoxia (N) as the control. Second, isolated hearts were Langendorff perfused under hypoxia (10% O(2), 30 min) and reoxygenated (94% O(2), 30 min) with or without 3 microM glibenclamide (nonselective K(+)(ATP) channel-blocker) or 100 microM diazoxide (selective mitochondrial K(+)(ATP) channel-opener). Blood gasses, hemoglobin concentration, and plasma malondialdehyde were similar in CH and CH+A and in both different from normoxic (P < 0.01), body weight gain and plasma nitrate/nitrite were higher in CH+A than CH (P < 0.01), whereas apoptosis (number of TUNEL-positive nuclei) was less in CH+A than CH (P < 0.05). During in vitro hypoxia, the efficiency (ratio of ATP production/pressure x rate product) was the same in all groups and diazoxide had no measurable effects on myocardial performance, whereas glibenclamide increased end-diastolic pressure more in N and CH than in CH+A hearts (P < 0.05). During reoxgenation, efficiency was markedly less in CH with respect to N and CH+A (P < 0.0001), and ratex pressure product remained lower in CH than N and CH+A hearts (P < 0.001), but glibenclamide or diazoxide abolished this difference. Glibenclamide, but not diazoxide, decreased vascular resistance in N and CH (P < 0.005 and < 0.001) without changes in CH+A. We hypothesize that cardioprotection in chronically hypoxic hearts derive from cell depolarization by sarcolemmal K(+)(ATP) blockade or from preservation of oxidative phosphorylation efficiency (ATP turnover/myocardial performance) by mitochondrial K(+)(ATP) opening. Therefore K(+)(ATP) channels are involved in the deleterious effects of chronic hypoxia and in the cardioprotection elicited when chronic hypoxia is interrupted with short normoxic aeration episodes.     

Localisation of the Vacuolar Proton Pump (V-H+-ATPase) and Carbonic Anhydrase II in the Human Eccrine Sweat Gland

The localisation of the vacuolar proton pump (V-H+ -ATPase) and the enzyme carbonic anhydrase II (CAII) was investigated in the human eccrine sweat gland employing standard immunohistochemical techniques after antigen retrieval using microwave heat treatment and high pressure. The high-pressure antigen retrieval unmasked the presence of V-H+ -ATPase in the clear cells of the secretory coil, with a distribution similar to that previously observed for CAII. However, the dark cells were unreactive to both antibodies. In addition, heat and high-pressure antigen retrieval demonstrated the presence of CAII in the apical zone of luminal cells of the reabsorptive duct, a location not previously reported. The localisation of V-H+ -ATPase and CAII in the secretory coil clear cells suggests that the formation of HCO3- and H+ by carbonic anhydrase II and the transport of H+ by V-H+ -ATPase may play an role in sweat fluid secretion. Their presence at the apex of the duct cells indicates involvement in ductal ion reabsorption.     

Clinical pharmacokinetics of 5-fluorouracil with consideration of chronopharmacokinetics

Even though 5-fluorouracil (FU) is one of the oldest anticancer drugs, its use in cancer chemotherapy continues to increase. Fluorouracil is a pro-drug that requires intracellular activation to exert its effects. This makes it difficult to associate blood drug concentration with cell toxicity directly, although data from the literature show the existence of such a relationship. The relationship between FU pharmacokinetics and patient response has been explored extensively and reports attest a link between systemic drug exposure and response and survival. This has led to the concept of maximal tolerated exposure, and strategies to achieve this rely on pharmacokinetic follow-up and individual dose adjustment. More than 80% of the administered FU dose is eliminated by catabolism through dihydropyrimidine dehydrogenase (DPD), the rate-limiting enzyme. Dihydropyrimidine dehydrogenase activity is found in most tissues but is highest in the liver. Peripheral blood mononuclear cells (PBMC) are used to monitor clinically DPD activity. A significant, but weak correlation between PBMC and liver DPD activity has been observed. The relationship between PBMC-DPD activity and FU systemic clearance is weak (r²=0.10); thus, simply determining PBMC-DPD is not sufficient to predict accurately FU clearance. Population pharmacokinetic analysis identified patient co-variables that influence FU clearance; drug kinetics is significantly reduced by increased age, high serum alkaline phosphatase, length of drug infusion, and low PBMC-DPD. Autoregulation of FU metabolism also is suggested; inhibition of DPD activity was observed after FU administration in both colorectal cancer patients and an animal model. Circadian rhythmicity in DPD activity is suggested from both human and animal investigations. In patients receiving protracted low dose 5-FU infusion, the circadian rhythm in FU plasma concentration peaks at 11:00h and is lowest at 23:00h, on average. The inverse relationship observed between the circadian profile of FU plasma concentration and PBMC-DP activity in these same patients suggests a link between DPD activity and FU pharmacokinetics. The impact of the biological time of drug administration was also studied with short venous infusions; clearance was 70% greater at 13:00h than at 01:00h. Similarly, peak drug concentration occurred in the first half of the night in patients receiving constant rate 5-FU infusion for 2-5 d. Several studies describe wide interindividual variation in the timing of the peak and trough of the 24h rhythm in DPD activity. The rational for FU chronomodulated therapy has been the circadian rhythm in host drug tolerance, which is greatest during the night time when the proliferation of normal target tissue is least. A randomized study of chronomodulated FU therapy with maximal delivery rate at 04:00h was shown clearly to be significantly more effective and less toxic than control flat FU therapy. Future research must focus on easy-to-obtain markers of specific rhythms to individualize the chronomodulated FU delivery.