A highly virulent variant of HIV-1 circulating in the Netherlands

We discovered a highly virulent variant of subtype-B HIV-1 in the Netherlands. One hundred nine individuals with this variant had a 0.54 to 0.74 log₁₀ increase (i.e., a ~3.5-fold to 5.5-fold increase) in viral load compared with, and exhibited CD4 cell decline twice as fast as, 6604 individuals with other subtype-B strains. Without treatment, advanced HIV-CD4 cell counts below 350 cells per cubic millimeter, with long-term clinical consequences-is expected to be reached, on average, 9 months after diagnosis for individuals in their thirties with this variant. Age, sex, suspected mode of transmission, and place of birth for the aforementioned 109 individuals were typical for HIV-positive people in the Netherlands, which suggests that the increased virulence is attributable to the viral strain. Genetic sequence analysis suggests that this variant arose in the 1990s from de novo mutation, not recombination, with increased transmissibility and an unfamiliar molecular mechanism of virulence.

Pesticide exposure and risk of systemic lupus erythematosus in an urban population of predominantly African-American women

OBJECTIVE

Past studies have reported associations between pesticide exposure and the risk of systemic lupus erythematosus (SLE). Residential pesticide exposure has been less well studied than agricultural exposure. The purpose of this study was to assess SLE risk associated with residential pesticide exposure in an urban population of predominantly African-American women.

METHODS

Adult women with SLE were identified from six hospital databases and community screening in three neighborhoods in Boston, Massachusetts, USA. Controls were adult women volunteers from the same neighborhoods who were screened for the absence of connective tissue disease and anti-nuclear antibodies. Subjects were considered exposed to pesticides if they had ever had an exterminator for an ant, cockroach, or termite problem prior to SLE diagnosis or corresponding reference age in controls. Risks associated with pesticide exposure were analyzed using multivariable logistic regression models, adjusted for sociodemographic factors.

RESULTS

We identified 93 SLE subjects and 170 controls with similar baseline characteristics. Eighty-three per cent were African-American. Pesticide exposure was associated with SLE, after controlling for potential confounders (odds ratio 2.24, 95% confidence interval 1.28-3.93).

CONCLUSION

Residential exposure to pesticides in an urban population of predominantly African-American women was associated with increased SLE risk. Additional studies are needed to corroborate these findings.

Designing an intervention for women with systemic lupus erythematosus from medically underserved areas to improve care: a qualitative study

OBJECTIVE

Systemic lupus erythematosus (lupus) disproportionately affects women, racial/ethnic minorities and low-income populations. We held focus groups for women from medically underserved communities to discuss interventions to improve care.

METHODS

From our Lupus Registry, we invited 282 women, ≥18 years, residing in urban, medically underserved areas. Hospital-based clinics and support groups also recruited participants. Women were randomly assigned to three focus groups. Seventy-five-minute sessions were recorded, transcribed and coded thematically using interpretative phenomenologic analysis and single counting methods. We categorized interventions by benefits, limitations, target populations and implementation questions.

RESULTS

Twenty-nine women with lupus participated in three focus groups, (n = 9, 9, 11). 80% were African American and 83% were from medically underserved zip codes. Themes included the desire for lupus education, isolation at the time of diagnosis, emotional and physical barriers to care, and the need for assistance navigating the healthcare system. Twenty of 29 participants (69%) favored a peer support intervention; 17 (59%) also supported a lupus health passport. Newly diagnosed women were optimal intervention targets. Improvements in quality of life and mental health were proposed outcome measures.

CONCLUSION

Women with lupus from medically underserved areas have unique needs best addressed with an intervention designed through collaboration between community members and researchers.

Transcription factories and nuclear organization of the genome

The dynamic compartmental organization of the transcriptional machinery in mammalian nuclei places particular constraints on the spatial organization of the genome. The clustering of active RNA polymerase I transcription units from several chromosomes at nucleoli is probably the best-characterized and universally accepted example. RNA polymerase II localization in mammalian nuclei occurs in distinct concentrated foci that are several-fold fewer in number compared to the number of active genes and transcription units. Individual transcribed genes cluster at these shared transcription factories in a nonrandom manner, preferentially associating with heterologous, coregulated genes. We suggest that the three-dimensional (3D) conformation and relative arrangement of chromosomes in the nucleus has a major role in delivering tissue-specific gene-expression programs.

An Aß concatemer with altered aggregation propensities

We present an analysis of the conformational and aggregative properties of an Aß concatemer (Con-Alz) of interest for vaccine development against Alzheimer's disease. Con-Alz consists of 3 copies of the 43 residues of the Aß peptide separated by the P2 and P30 T-cell epitopes from the tetanus toxin. Even in the presence of high concentrations of denaturants or fluorinated alcohols, Con-Alz has a very high propensity to form aggregates which slowly coalesce over time with changes in secondary, tertiary and quaternary structure. Only micellar concentrations of SDS were able to inhibit aggregation. The increase in the ability to bind the fibril-binding dye ThT increases without lag time, which is characteristic of relatively amorphous aggregates. Confirming this, electron microscopy reveals that Con-Alz adopts a morphology resembling truncated protofibrils after prolonged incubation, but it is unable to assemble into classical amyloid fibrils. Despite its high propensity to aggregate, Con-Alz does not show any significant ability to permeabilize vesicles, which for fibrillating proteins is taken to be a key factor in aggregate cytotoxicity and is attributed to oligomers formed at an early stage in the fibrillation process. Physically linking multiple copies of the Aß-peptide may thus sterically restrict Con-Alz against forming cytotoxic oligomers, forcing it instead to adopt a less well-organized assembly of intermeshed polypeptide chains.

Atmospheric trends in methylchloroform and the global average for the hydroxyl radical

Frequent atmospheric measurements of the anthropogenic compound methylchloroform that were made between 1978 and 1985 indicate that this species is continuing to increase significantly around the world. Reaction with the major atmospheric oxidant, the hydroxyl radical (OH), is the principal sink for this species. The observed mean trends for methylchloroform are 4.8, 5.4, 6.4, and 6.9 percent per year at Aldrigole (Ireland) and Cape Meares (Oregon), Ragged Point (Barbados), Point Matatula (American Samoa), and Cape Grim (Tasmania), respectively, from July 1978 to June 1985. These measured trends, combined with knowledge of industrial emissions, were used in an optimal estimation inversion scheme to deduce a globally averaged methylchloroform atmospheric lifetime of 6.3 (+ 1.2, -0.9) years (1sigma uncertainty) and a globally averaged tropospheric hydroxyl radical concentration of (7.7 +/- 1.4) x 10(5) radicals per cubic centimeter (1sigma uncertainty). These 7 years of gas chromatographic measurements, which comprise about 60,000 individual calibrated real-time air analyses, provide the most accurate estimates yet of the trends and lifetime of methylchloroform and of the global average for tropospheric hydroxyl radical levels. Accurate determination of hydroxyl radical levels is crucial to understanding global atmospheric chemical cycles and trends in the levels of trace gases such as methane.

Development and initial validation of a self-assessed lupus organ damage instrument

OBJECTIVE

The Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SDI) is a validated instrument for assessing organ damage in systemic lupus erythematosus (SLE). Trained physicians must complete it, thus limiting utility where this is impossible.

METHODS

We developed and pilot tested a self-assessed organ damage instrument, the Lupus Damage Index Questionnaire (LDIQ), in 37 SLE subjects and 7 physicians. After refinement, 569 English-speaking SLE subjects and 14 rheumatologists from 11 international SLE clinics participated in validation. Subjects and physicians completed the instruments separately. We calculated sensitivity, specificity, Spearman's correlations, and agreement using the SDI as the gold standard. Six hundred five SLE participants in the community-based National Data Bank for Rheumatic Diseases (NDB) study completed the LDIQ and we assessed correlations with outcome and disability measures.

RESULTS

The mean LDIQ score was 3.3 (range 0-16) and the mean SDI score was 1.5 (range 0-9). The LDIQ had a moderately high correlation with the SDI (Spearman's r = 0.50, P < 0.001). Specificities of individual LDIQ items were >80%, except for neuropathy. Sensitivities were variable and lowest for damage, with <1% prevalence. Agreement between the SDI and LDIQ was >85% for all but neuropathy, reduced renal function, deforming arthritis, and alopecia. In the NDB, the LDIQ correlated well with the comorbidity index (r = 0.45), the Short Form 36 physical component scale (r = 0.43), the Medical Research Council dyspnea scale (r = 0.40), disability (r = 0.37), and the Systemic Lupus Erythematosus Activity Questionnaire score (r = 0.37).

CONCLUSION

The metric properties of the LDIQ are good compared with the SDI. It has construct validity and correlations with health assessments similar to the SDI. The LDIQ should allow expansion of SLE research. Its ultimate value will be determined in longitudinal studies.

Coupled-channel evaluations of cross sections for scattering involving particle-unstable resonances

How does the scattering cross section change when the colliding bound-state fragments are allowed particle-emitting resonances? This question is explored in the framework of a multichannel algebraic scattering method of determining nucleon-nucleus cross sections at low energies. Two cases are examined, the first being a gedanken investigation in which n + 12C scattering is studied with the target states assigned artificial widths. The second is a study of neutron scattering from 8Be, a nucleus that is particle unstable. Resonance character of the target states markedly varies evaluated cross sections from those obtained assuming stability in the target spectrum.

Proteoglycans and amyloid fibrillogenesis

A brief discussion of the general structure of proteoglycans is followed by a description of the diverse nature of amyloids. Using the murine form of inflammation-associated (AA) amyloid, we have examined the temporal and anatomical relationship between the heparan sulfate proteoglycan, its mRNA and AA amyloid deposition in vivo. The in vitro effect of heparan sulfate on the secondary structure of amyloid precursors, and on amyloid peptides, suggests that this interaction is important in amyloidogenesis. The relationship of these two components likely reflects a more general process taking place between basement membrane proteins (which may be synthesized by a variety of cell types within and outside the CNS) and amyloid precursors. A general definition of in vivo amyloid deposits emerges from these considerations as do concepts for interfering with amyloidogenesis. Preliminary results showing the effect of small molecule aliphatic sulfonates and sulfates on in vitro amyloid beta-protein fibrillogenesis and AA amyloidogenesis in vivo supports the general process presented and suggests therapeutic strategies for treating amyloid-based diseases.

Antibody targeting of TIRC7 results in significant therapeutic effects on collagen-induced arthritis in mice

TIRC7 is a cell surface molecule which is expressed in T and B lymphocytes and negatively regulates their function. Anti-TIRC7 specific monoclonal antibody (mAb) inhibited T cell memory response to recall antigens. Up-regulation of TIRC7 on lymphocytes from joint tissue of patients with Rheumatoid Arthritis (RA) and mice with collagen induced arthritis (CIA) suggested TIRC7 as a novel target to promote anti-inflammatory reaction. Anti-TIRC7 mAb administration significantly inhibited the induction and progression of CIA and the anti-collagen IgG1 and IgG2a antibody response. Combination therapy of anti-TIRC7 mAb and soluble TNF-alpha receptor demonstrated an increased inhibitory effect over the single compounds on CIA. The results demonstrate the therapeutic potential of TIRC7 targeting with mAb in diseases associated with exaggerated T and B cell responses.

LMO2-associated clonal T cell proliferation in two patients after gene therapy for SCID-X1

We have previously shown correction of X-linked severe combined immunodeficiency [SCID-X1, also known as gamma chain (gamma(c)) deficiency] in 9 out of 10 patients by retrovirus-mediated gamma(c) gene transfer into autologous CD34 bone marrow cells. However, almost 3 years after gene therapy, uncontrolled exponential clonal proliferation of mature T cells (with gammadelta+ or alphabeta+ T cell receptors) has occurred in the two youngest patients. Both patients' clones showed retrovirus vector integration in proximity to the LMO2 proto-oncogene promoter, leading to aberrant transcription and expression of LMO2. Thus, retrovirus vector insertion can trigger deregulated premalignant cell proliferation with unexpected frequency, most likely driven by retrovirus enhancer activity on the LMO2 gene promoter.

Maintaining updated DNA-based HLA assignments in the National Marrow Donor Program Bone Marrow Registry

The National Marrow Donor Program (NMDP) has instituted an approach to address the impact of new alleles on the DNA-based HLA assignments obtained during volunteer donor typing. This approach was applied to the DRB typing results from 371,187 donors received from 14 laboratories in 1999. Samples were tested with a standardized set of sequence specific oligonucleotide reagents and the positive and negative hybridization results transmitted electronically to the NMDP. A software program interpreted the primary data into HLA assignments and rejected assignments which did not produce a result at the specified level of resolution. Comparison of the HLA assignments derived by the NMDP software to the assignments made by the laboratories using several local software prograins showed 90.5% of the assignments to be identical. Differences in assignments were explained by varying levels of typing resolution, variation in the inclusion of the second expressed DRB loci, disparity arising when alternative assignments were summarized, and failure to submit correct information. When the primary data collected in 1999 were interpreted into HLA assignments using the set of alleles defined in July 2000, 74% of the HLA-DRB assignments were altered by the description of new alleles, justifying the development of this software.

Etanercept in the treatment of adult patients with Still's disease

OBJECTIVE

To evaluate the safety and efficacy of etanercept in the treatment of adult patients with Still's disease.

METHODS

Twelve adult patients who met criteria for Still's disease and had active arthritis were enrolled in a 6-month open-label trial of etanercept given in biweekly doses of 25 mg. The mean disease duration at study entry was 10.7 years. All patients had been treated unsuccessfully with other disease-modifying antirheumatic drugs. Efficacy was evaluated according to American College of Rheumatology (ACR) improvement criteria, and adverse events were recorded.

RESULTS

Ten patients successfully completed the study; 2 withdrew due to disease flare. In 4 patients, the dosage of etanercept was increased from 25 mg biweekly to 25 mg 3 times per week. Seven patients met ACR 20% response criteria. Of these 7 responders, 4 met ACR 50% response criteria and 2 met ACR 70% response criteria. Among the 3 patients with systemic features of Still's disease (fever and rash), improvement in these features was seen in 1; the arthritis did not improve in any of these 3 patients. Except in the 2 patients who withdrew due to disease flare (rash, fever, and arthritis), no other significant adverse events occurred.

CONCLUSION

In this initial study of etanercept therapy for Still's disease in the adult, this treatment resulted in improvement in the arthritis and was well tolerated. Additional trials should be performed to elucidate the effects of tumor necrosis factor inhibitors in Still's disease.

Disturbed activation of endoplasmic reticulum stress transducers by familial Alzheimer's disease-linked presenilin-1 mutations

Recent studies have shown independently that presenilin-1 (PS1) null mutants and familial Alzheimer's disease (FAD)-linked mutants should both down-regulate signaling of the unfolded protein response (UPR). However, it is difficult to accept that both mutants possess the same effects on the UPR. Furthermore, contrary to these observations, neither loss of PS1 and PS2 function nor expression of FAD-linked PS1 mutants were reported to have a discernable impact on the UPR. Therefore, re-examination and detailed analyses are needed to clarify the relationship between PS1 function and UPR signaling. Here, we report that PS1/PS2 null and dominant negative PS1 mutants, which are mutated at aspartate residue 257 or 385, did not affect signaling of the UPR. In contrast, FAD-linked PS1 mutants were confirmed to disturb UPR signaling by inhibiting activation of both Ire1alpha and ATF6, both of which are endoplasmic reticulum (ER) stress transducers in the UPR. Furthermore, PS1 mutants also disturbed activation of PERK (PKR-like ER kinase), which plays a crucial role in inhibiting translation during ER stress. Taken together, these observations suggested that PS1 mutations could affect signaling pathways controlled by each of the respective ER-stress transducers, possibly through a gain-of-function.

Mutation of conserved aspartates affect maturation of presenilin 1 and presenilin 2 complexes

Presenilin (PS1 and PS2) holoproteins are transiently incorporated into low molecular weight (MW) complexes. During subsequent incorporation into a higher MW complex, they undergo endoproteolysis to generate stable N- and C-terminal fragments (NTF/CTF). Mutation of either of two conserved aspartate residues in transmembrane domains inhibits both presenilin-endoproteolysis and the proteolytic processing of APP and Notch. We show that aspartate-mutant holoprotein presenilins are not incorporated into the high molecular weight, NTF/CTF-containing complexes. Aspartate-mutant presenilin holoproteins also preclude entry of endogenous wild-type PS1/PS2 into the high molecular weight complexes, but do not affect the incorporation of wild-type holoproteins into lower molecular weight holoprotein complexes. These data suggest that the loss-of-function aspartate-mutants cause altered PS complex maturation, and argue that the functional presenilin moieties are contained in the high molecular weight presenilin NTF/CTF-containing complexes.

Activation of the beta globin locus by transcription factors and chromatin modifiers

Locus control regions (LCRs) alleviate chromatin-mediated transcriptional repression. Incomplete LCRs partially lose this property when integrated in transcriptionally restrictive genomic regions such as centromeres. This frequently results in position effect variegation (PEV), i.e. the suppression of expression in a proportion of the cells. Here we show that this PEV is influenced by the heterochromatic protein SUV39H1 and by the Polycomb group proteins M33 and BMI-1. A concentration variation of these proteins modulates the proportion of cells expressing human globins in a locus-dependent manner. Similarly, the transcription factors Sp1 or erythroid Krüppel-like factor (EKLF) also influence PEV, characterized by a change in the number of expressing cells and the chromatin structure of the locus. However, in contrast to results obtained in a euchromatic locus, EKLF influences the expression of the gamma- more than the beta-globin genes, suggesting that the relief of silencing is caused by the binding of EKLF to the LCR and that genes at an LCR proximal position are more likely to be in an open chromatin state than genes at a distal position.

Nicastrin modulates presenilin-mediated notch/glp-1 signal transduction and betaAPP processing

Nicastrin, a transmembrane glycoprotein, forms high molecular weight complexes with presenilin 1 and presenilin 2. Suppression of nicastrin expression in Caenorhabditis elegans embryos induces a subset of notch/glp-1 phenotypes similar to those induced by simultaneous null mutations in both presenilin homologues of C. elegans (sel-12 and hop-1). Nicastrin also binds carboxy-terminal derivatives of beta-amyloid precursor protein (betaAPP), and modulates the production of the amyloid beta-peptide (A beta) from these derivatives. Missense mutations in a conserved hydrophilic domain of nicastrin increase A beta42 and A beta40 peptide secretion. Deletions in this domain inhibit A beta production. Nicastrin and presenilins are therefore likely to be functional components of a multimeric complex necessary for the intramembranous proteolysis of proteins such as Notch/GLP-1 and betaAPP.

Spatial learning in transgenic mice expressing human presenilin 1 (PS1) transgenes

Dominant mutations in the Presenilin 1 gene are linked to an aggressive, early-onset form of familial Alzheimer's Disease (FAD). Spatial memory of transgenic (Tg) mice expressing either mutant (lines Tg(M146L)1, Tg(M146L)76, Tg(L286V)198) or wild type (line Tg(PS1wt)195) human PS1 transgenes was investigated in the Morris water maze (WM) test at 6 and 9 months of age. The results showed that the mutated Tg mice had increased swim speed when compared to non-Tg littermates or Tg PS1 wild type mice. The swim speed difference did not, however, significantly affect the spatial learning in the WM test and all groups showed comparable search paths during training and similar spatial bias during probe trials. When re-tested at 9 months, all mice showed significantly improved learning acquisition of spatial information. The lack of progressive spatial learning impairment in mice expressing the mutated human PS1 transgene in the WM does not preclude impairments in other cognitive tasks but suggests that full phenotypic expression of mutant PS1 alleles may require co-expression of human versions of other AD-associated genes.

Establishment of a smoking cessation programme in primary and secondary care in Canterbury

AIMS

Smokescreen for the 1990's is a smoking cessation programme devised for use in primary care in Australia. It is based on the 'readiness to change' model where smokers are categorised as being 'ready', 'unsure', or 'not ready' to quit smoking. Those in the 'ready' group are encouraged to set a quit date and offered nicotine replacement therapy. Those in the unsure group receive brief motivational intervention, and those 'not ready' are given simple health advice. The aims of the study were to evaluate the process and outcome of establishing this program in primary and secondary care in Christchurch.

METHODS

Process evaluation involved all staff participating in the program. Patient outcomes including quit rates were assessed by interview six months after enrollment.

RESULTS

Implementation was successful with 59 general practitioners, 49 practice nurses and 294 hospital staff receiving education in the use of the programme. Nine hundred and seven patients (smokers) were enrolled in the study, 347 from primary care and 560 from Christchurch Hospital. The point prevalence abstinence rate at 6 months was 10.4% for the primary care sample and 17% for the secondary care group, with an overall rate of 14.4%.

CONCLUSIONS

The programme was successfully implemented across primary and secondary care with an acceptable quit rate at 6 months.

Intergenic transcription and developmental remodeling of chromatin subdomains in the human beta-globin locus

Gene activation requires chromatin remodeling complexes, which hyperacetylate histones and enable factor access; however, the targeting mechanisms leading to the establishment and maintenance of large, hyperacetylated DNase-sensitive chromatin domains are unknown. Recent work has shown that histone acetyltransferases are associated with RNA-pol II complexes, suggesting that transcription of chromatin plays a role in chromatin modification. Here we show the human beta-globin locus is divided into three differentially activated chromatin subdomains. Large transcripts precisely delineate the active domains at key cell cycle points associated with chromatin transitions and remodeling. We identify an element that initiates these transcripts, located in a region required for chromatin activation. The results suggest that intergenic transcription is required for chromatin remodeling of chromosomal domains.

New clothes for amyloid enhancing factor (AEF): silk as AEF

Amyloid enhancing factor (AEF) is an activity that appears naturally during the course of persistent inflammation and precedes, by 24-48 h, AA amyloid deposition in appropriate murine models. AEF is defined by its biological properties, namely, when administered intravenously or intraperitoneally to a mouse, it primes the recipient for the rapid induction of AA amyloid when they are given an inflammatory stimulus. Available evidence indicates that AEF is protein in nature, but a specific molecular species (if a singular species exits) has not been identified. Past work (Ganowiak et al., Biochem. Biophys. Res. Commun. 199:306-312, 1994) has shown that AEF activity may be imparted to two different proteins (IAPP and beta-protein) provided each is organized in the form of an amyloid fibril. Since a characteristic property of proteins in amyloid fibrils is their beta-sheet organization, one possibility is that AEF activity, in part, depends on such organization, and other proteins with such properties may also have AEF activity. To investigate this possibility, silk, a protein which contains substantial beta-sheet content, was denatured in LiSCN and allowed to renature slowly under reducing conditions to form a gel. The denatured silk preparation was then sonicated thoroughly to permit intravenous injection and assessed for AEF activity. The modified silk, presented as small fibrils in a beta-sheet conformation as assessed by electron microscopy and circular dichroism, respectively. This silk at 0-50 micrograms/animal was administered intravenously as "AEF" followed immediately by subcutaneous AgNO3 as the inflammatory stimulus. Six days later the spleens were examined for the presence of AA amyloid and following Congo red staining, the amount of amyloid quantified by image analysis. Modified silk without an inflammatory stimulus, and non-sonicated modified silk, failed to induce AA amyloid. Sonicated modified silk followed by AgNO3 induced large quantities of splenic AA amyloid in a dose dependent fashion. Modified silk in quantities as small as 1-5 micrograms/animal can function as AEF. The AEF properties of the modified silk were stable at 4 degrees C for at least 4 weeks (the longest period tested). This procedure may provide a means of standardizing AEF preparations.

Mechanisms of developmental control of transcription in the murine alpha- and beta-globin loci

We have characterized mRNA expression and transcription of the mouse alpha- and beta-globin loci during development. S1 nuclease and primary transcript in situ hybridization analyses demonstrate that all seven murine globin genes (zeta, alpha1, alpha2, epsilony, betaH1, betamaj, and betamin) are transcribed during primitive erythropoiesis, however transcription of the zeta, epsilony, and betaH1 genes is restricted to the primitive erythroid lineage. Transcription of the betamaj and betamin genes in primitive cells is EKLF-dependent demonstrating EKLF activity in embryonic red cells. Novel kinetic analyses suggest that multigene expression in the beta locus occurs via alternating single-gene transcription whereas coinitiation cannot be ruled out in the alpha locus. Transcriptional activation of the individual murine beta genes in primitive cells correlates inversely with their distance from the locus control region, in contrast with the human beta locus in which the adult genes are only activated in definitive erythroid cells. The results suggest that the multigene expression mechanism of alternating transcription is evolutionarily conserved between mouse and human beta globin loci but that the timing of activation of the adult genes is altered, indicating important fundamental differences in globin gene switching.

Cancer mortality in relation to monitoring for radionuclide exposure in three UK nuclear industry workforces

Cancer mortality in 40,761 employees of three UK nuclear industry facilities who had been monitored for external radiation exposure was examined according to whether they had also been monitored for possible internal exposure to tritium, plutonium or other radionuclides (uranium, polonium, actinium or other unspecified). Death rates from cancer were compared both with national rates and with rates in radiation workers not monitored for exposure to any radionuclides. Among workers monitored for tritium exposure, overall cancer mortality was significantly below national rates [standardized mortality ratio (SMR) = 83, 165 deaths; 2P = 0.02] and none of the cancer-specific death rates was significantly above either the national average or rates in non-monitored workers. Although the overall death rate from cancer in workers monitored for plutonium exposure was also significantly low relative to national rates (SMR = 89, 581 deaths; 2P = 0.005), mortality from pleural cancer was significantly raised (SMR = 357, nine deaths; 2P = 0.002); none of the rates differed significantly from those of non-monitored workers. Workers monitored for radionuclides other than tritium or plutonium also had a death rate from all cancers combined that was below the national average (SMR = 86, 418 deaths; 2P = 0.002) but prostatic cancer mortality was raised both in relation to death rates in the general population (SMR = 153, 37 deaths; 2P = 0.02) and to death rates in radiation workers who had not been monitored for exposure to any radionuclide [rate ratio (RR) = 1.65; 2P = 0.03]. Mortality from cancer of the lung was also significantly increased in workers monitored for other radionuclides compared with those of radiation workers not monitored for exposure to radionuclides (RR = 1.31, 164 deaths; 2P = 0.01). For cancers of the lung, prostate and all cancers combined, death rates in monitored workers were examined according to the timing and duration of monitoring for radionuclide exposure, with rates of radiation workers not monitored for any radionuclide forming the comparison group. In tritium-monitored workers, RRs for prostatic cancer varied significantly according to the number of years in which they were monitored (2P = 0.03). In workers monitored for plutonium exposure, RRs for all cancers combined increased with the number of years in which they were monitored (2P = 0.04) and with the number of years since first monitoring (2P = 0.0003). There was little suggestion of systematic variation in RRs for workers monitored for other radionuclides in relation to the timing or duration of monitoring, nor did it appear that their raised rates of cancer of the lung and prostate were explained by external radiation dose. These analyses of cancer mortality in relation to monitoring for radionuclide exposure reported in a large cohort of nuclear industry workers suggest that certain patterns of monitoring for some radionuclides may be associated with higher death rates from cancers of the lung, pleura, prostate and all cancers combined. Some of these findings may be due to chance. Moreover, because of the paucity of related data and lack of information about other possible exposures, such as whether plutonium workers are more likely to be exposed to asbestos, firm conclusions cannot be drawn at this stage. Further investigations of the relationship between radionuclide exposure and cancer in nuclear industry workers are needed.

Chromatin interaction mechanism of transcriptional control in vivo

We have used a kinetic analysis to distinguish possible mechanisms of activation of transcription of the different genes in the human beta globin locus. Based on in situ studies at the single-cell level we have previously suggested a dynamic mechanism of single genes alternately interacting with the locus control region (LCR) to activate transcription. However, those steady-state experiments did not allow a direct measurement of the dynamics of the mechanism and the presence of loci with in situ primary transcript signals from two beta-like genes in cis has left open the possibility that multiple genes in the locus could initiate transcription simultaneously. Kinetic assays involving removal of a block to transcription elongation in conjunction with RNA FISH show that multiple beta gene primary transcript signals in cis represent a transition between alternating transcriptional periods of single genes, supporting a dynamic interaction mechanism.

The dynamics of globin gene expression and gene therapy vectors

The most important level of regulation of the beta-globin genes is by activation of all of the genes by the Locus Control Region (LCR) and repression of the early genes by an as yet unknown factor acting on sequences flanking the genes. Superimposed on this is a mechanism in which the early genes (epsilon and gamma) suppress the late genes (delta and beta) by competition for the interaction with the LCR. Although this extra level of gene regulation is quantitatively of less importance than the direct repression mechanism, it has important implications and has provided an excellent assay system to probe the regulation of transcription at the single cell level. These studies indicate that the LCR interacts with individual globin genes and that LCR/gene interactions are dynamic with complexes forming and dissociating continually. The levels of expression of each of the genes appear to depend on: 1) the frequency of interaction which is itself dependent on the distance of the gene to the LCR, 2) the affinity of the LCR for the gene and 3) the stability of the LCR/gene complex. The latter two are dependent on the balance of transcription factors. We conclude that transcription only appears to take place while the LCR and gene interact and that the level of transcription is determined by the frequency and duration of such interaction rather than by changes in the rate of transcription of promoters.

Locus control regions, chromatin activation and transcription

The past year has seen interesting advances in our understanding of the action of locus control regions. For the first time, the chromosomal distance was described in detail as a parameter in positive/negative regulation of transcription via gene competition. A number of publications have also described negative regulatory elements which restrict the action of locus control regions and other regulatory regions to specific genes and/or specific tissues. The emerging picture indicates that several very different types of negative regulation ensure that transcriptional activation occurs only in the appropriate cells.

The dynamics of globin gene expression and position effects

We have used gene competition to study the regulation of the human beta-globin locus in transgenic mice as a model system of a multigene locus. The locus is regulated by the locus control region (LCR), which is required for the expression of all the genes. Analysis of the locus at the single-cell level shows that the LCR appears to interact directly with the genes via a looping mechanism. This interaction is monogenic, and the level of transcription is determined by the frequency and stability of LCR/gene complex formation. These parameters are dependent both on the distance between the LCR and gene(s), and the concentration of transcription factors in the nucleus. Disturbance of complex formation leads to position effects, particularly when the locus is integrated in a heterochromatic environment.

Single-dose dexamethasone paclitaxel premedication

Paclitaxel is one of the most active chemotherapy agents for the treatment of ovarian and other gynecologic cancers. Hypersensitivity reactions (HSR) remain one of the major clinical concerns in the use of paclitaxel. This report deals with 183 consecutive patients treated with paclitaxel chemotherapy. A total of 1010 cycles were administered. Premedication consisted of single-dose intravenous decadron, benadryl, and cimetidine administered immediately prior to chemotherapy. Four hypersensitivity reactions occurred. All patients recovered uneventfully from these reactions. Two of these patients received additional oral decadron followed by the standard premedication and were successfully retreated with multiple courses of paclitaxel therapy without reaction. Our findings confirm other reports that paclitaxel chemotherapy hypersensitivity reactions can be decreased with a single-dose intravenous decadron premedication regimen and that patients who do have paclitaxel HSRs may be safely retreated with paclitaxel.

The dynamics of globin gene expression and gene therapy vectors

The most important level of the regulation of the beta-globin genes is by activation of all of the genes by the locus control region (LCR). Part of the developmental regulation of the locus is achieved by competition of the genes for the interaction with the LCR. Although this level of gene regulation is quantitatively of less importance than the direct repression mechanism for the early genes, it has important implications and has provided an excellent assay to probe the regulation of transcription at the single cell level. The results of these studies indicate that the LCR interacts with individual globin genes and that LCR/gene interactions are dynamic with complexes forming and dissociating continually. We conclude that transcription only appears to take place while the LCR and gene interact and that the level of transcription is determined by the frequency and duration of such interaction rather than by changes in the rate of transcription of the promoters. This mechanism has clear implications for the design of vectors for the purpose of gene therapy.

Clonally expanded Valpha12+ (AV12S1),CD8+ T cells from a patient with rheumatoid arthritis are autoreactive

OBJECTIVE

Previously, we showed that 15-20% of patients with rheumatoid arthritis (RA) have oligoclonal expansions of peripheral blood CD8+ T cells expressing T cell receptors encoded by the V(alpha)12 (AV12S1) gene. To better understand the significance of these expansions, the present study was undertaken to determine their specificity.

METHODS

We cloned and characterized V(alpha)12+,CD8+ T cells from the peripheral blood of 1 RA patient with a clonal expansion of these T cells.

RESULTS

The T cell clones were autoreactive since they recognized autologous, but not allogeneic, antigen-presenting cells. Upon activation, these T cells secreted interleukin-4 and interleukin-10. The autoreactive T cell clones were class I major histocompatibility complex (MHC) restricted, by either HLA-B60 or HLA-Cw3.

CONCLUSION

A large population of class I MHC-restricted CD8+ T cells in a patient with RA is clonally expanded and autoreactive. These cells define a novel immune aberration in RA and provide a tool for defining the autoantigens that activate expanded T cell populations in vivo.

Mechanisms of developmental regulation in globin loci

Recent advances in the study of globin gene switching in the context of the complete locus have contributed greatly to our understanding of the mechanisms of developmental regulation. It has become clear that the interactions between the distant locus control region and the individual globin genes, as well as the trans-acting factors and physical parameters that affect these interactions, are crucial determinants in the developmental modulation of globin gene expression. This review concentrates on recent advances in the highly studied human beta-globin locus and will compare and contrast data from the human alpha-globin locus as well as the alpha and beta loci from other species where appropriate.

The effect of distance on long-range chromatin interactions

We have used gene competition to distinguish between possible mechanisms of transcriptional activation of the genes of the human beta-globin locus. The insertion of a second beta-globin gene at different points in the locus shows that the more proximal beta gene competes more effectively for activation by the locus control region (LCR). Reducing the relative distance between the genes and the LCR reduces the competitive advantage of the proximal gene, a result that supports activation by direct interaction between the LCR and the genes. Visualization of the primary transcripts shows that the level of transcription is proportional to the frequency of transcriptional periods and that such periods last approximately 8 min in vivo. We also find that the position of the beta-globin gene in the locus is important for correct developmental regulation.

Intergenic transcription and transinduction of the human beta-globin locus

We have identified novel nuclear transcripts in the human beta-globin locus using nuclear run-on analysis in erythroid cell lines and in situ hybridization analysis of erythroid tissue. These transcripts extend across the LCR and intergenic regions but are undetectable in nonerythroid cells. Surprisingly, transient transfection of a beta-globin gene (epsilon, gamma, or beta) induces transcription of the LCR and intergenic regions from the chromosomal beta-globin locus in nonerythroid cell lines. The beta-globin genes themselves, however, remain transcriptionally silent. Induction is dependent on transcription of the globin gene in the transfected plasmid but does not require protein expression. Using in situ hybridization analysis, we show that the plasmid colocalizes with the endogenous beta-globin locus providing insight into the mechanism of transinduction.

Evidence for phosphorylation and oligomeric assembly of presenilin 1

Pathogenic mutations in presenilin 1 (PS1) are associated with approximately 50% of early-onset familial Alzheimer disease. PS1 is endoproteolytically cleaved to yield a 30-kDa N-terminal fragment (NTF) and an 18-kDa C-terminal fragment (CTF). Using COS7 cells transfected with human PS1, we have found that phorbol 12, 13-dibutyrate and forskolin increase the state of phosphorylation of serine residues of the human CTF. Phosphorylation of the human CTF resulted in a shift in electrophoretic mobility from a single major species of 18 kDa to a doublet of 20-23 kDa. This mobility shift was also observed with human PS1 that had been transfected into mouse neuroblastoma (N2a) cells. Treatment of the phosphorylated CTF doublet with phage lambda protein phosphatase eliminated the 20- to 23-kDa doublet while enhancing the 18-kDa species, consistent with the interpretation that the electrophoretic mobility shift was due to the addition of phosphate to the 18-kDa species. The NTF and CTF eluted from a gel filtration column at an estimated mass of over 100 kDa, suggesting that these fragments exist as an oligomerized species. Upon phosphorylation of the PS1 CTF, the apparent mass of the NTF- or CTF-containing oligomers was unchanged. Thus, the association of PS1 fragments may be maintained during cycles of phosphorylation/dephosphorylation of the PS1 CTF.

Evaluation of beta-globin gene therapy constructs in single copy transgenic mice

Effective gene therapy constructs based on retrovirus or adeno-associated virus vectors will require regulatory elements that direct expression of genes transduced at single copy. Most beta-globin constructs designed for therapy of beta-thalassemias are regulated by the 5'HS2 component of the locus control region (LCR). Here we show that a human beta-globin gene flanked by two small 5'HS2 core elements or flanked by a 5'HS3 (footprints 1-3) core and a 5'HS2 core are not reproducibly expressed in single copy transgenic mice. In addition, low copy transgene concatamers that contain only dimer 5'HS2 cores fail to express, whereas those that contain monomer 5'HS2 cores express at 14% per copy. These data suggest that spacing between HS cores is crucial for LCR activity. We therefore constructed a novel 3.0 kb LCR cassette in which the 5'HS2, 5'HS3 and 5'HS4 cores are each separated by approximately 700 bp. When linked to the 815 bp beta-globin promoter this LCR directs 45% levels of expression from four independent single copy transgenes. However, the 3.0 kb LCR linked to the 265 bp promoter expresses variable levels, averaging 18%, from three single copy transgenes. Our findings suggest that sequences in the distal promoter play a role in single copy transgene activation and that larger LCR and promoter elements are most suitable for gene therapy applications.

Phosphorylation, subcellular localization, and membrane orientation of the Alzheimer's disease-associated presenilins

Presenilins 1 and 2 are unglycosylated proteins with apparent molecular mass of 45 and 50 kDa, respectively, in transfected COS-1 and Chinese hamster ovary cells. They colocalize with proteins from the endoplasmic reticulum and the Golgi apparatus in transfected and untransfected cells. In COS-1 cells low amounts of intact endogeneous presenilin 1 migrating at 45 kDa are detected together with relative larger amounts of presenilin 1 fragments migrating between 18 and 30 kDa. The presenilins have a strong tendency to form aggregates (mass of 100-250 kDa) in SDS-polyacrylamide gel electrophoresis, which can be partially resolved when denatured by SDS at 37 degrees C instead of 95 degrees C. Sulfation, glycosaminoglycan modification, or acylation of the presenilins was not observed, but both proteins are posttranslationally phosphorylated on serine residues. The mutations Ala-246 --> Glu or Cys-410 --> Tyr that cause Alzheimer's disease do not interfere with the biosynthesis or phosphorylation of presenilin 1. Finally, using low concentrations of digitonin to selectively permeabilize the cell membrane but not the endoplasmic reticulum membrane, it is demonstrated that the two major hydrophilic domains of presenilin 1 are oriented to the cytoplasm. The current investigation documents the posttranslational modifications and subcellular localization of the presenilins and indicates that postulated interactions with amyloid precursor protein metabolism should occur in the early compartments of the biosynthetic pathway.