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Biomedical subjects

G Jones

Publications and source records attributed to G Jones.

At least 109 records · Page 6Linked to original sources
PubMed2000

Interferon-gamma-induced apoptotic responses of Fanconi anemia group C hematopoietic progenitor cells involve caspase 8-dependent activation of caspase 3 family members.

Hematopoietic progenitor cells (HPC) from mice nullizygous at the Fanconi anemia (FA) group C locus and children with Fanconi anemia group C (FA-C) are hypersensitive to interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha. This hypersensitivity results, in part, from the capacity of these cytokines to prime the fas pathway. Because fas-mediated programmed cell death in many cells involves sequential activation of specific caspases, we tested the hypothesis that programmed cell death in FA HPC involves the ordered activation of specific caspase molecules. Lysates from lymphoblasts treated with both agonistic anti-fas antibody and IFN-gamma contained activated caspase 3 family members (caspases 3, 6, and 7), as well as caspase 8, whereas activation of caspases 1, 2, 4, 9, and 10 was not detected. The apoptotic effects of fas agonists in IFN-gamma-treated human and murine FA-C cells were blocked when pretreated with inhibitors (ac-DEVD-cho, CP-DEVD-cho, Z-DEVD-FMK) of the caspase 3 protease. Inhibitors (ac-YVAD-cho, CP-YVAD-cho, Z-YVAD-FMK) of caspase 1 did not block apoptosis or caspase 3 activation. Treatment of FA cells with the fluoromethyl ketone tetrapeptide caspase 8 inhibitor (ac-IETD-FMK) did suppress caspase 3 activation. A 4-fold greater fraction of IFN-induced FA-C cells expressed caspase 3 than FA-C cells complemented by retroviral-mediated transfer of FANCC. Therefore fas-induced apoptosis in Fanconi anemia cells of the C type involves the activation of caspase 8, which controls activation of caspase 3 family members and one direct or indirect function of the FANCC protein is to suppress apoptotic responses to IFN-gamma upstream of caspase 3 activation. (Blood. 2000;96:4204-4211)

Animals↗
PubMed2000

Vertebral fracture risk with long-term corticosteroid therapy: prevalence and relation to age, bone density, and corticosteroid use.

BACKGROUND: Few data are available regarding vertebral fracture risk in patients treated with oral corticosteroids. The aim of this study was to determine the prevalence and the role of risk factors such as age, bone mineral density (BMD), and corticosteroid use for vertebral deformity in patients receiving long-term corticosteroid therapy. METHODS: Thoracolumbar x-ray films, BMD, and details on corticosteroid use were obtained on 229 consecutive patients treated with long-term corticosteroid regimens (> or = 6 months of prednisone, > or = 5mg/d or equivalent) seen at 4 referral centers. Comparisons were made with a population control group of 286 male and female controls not taking corticosteroids (aged > or = 60 years). RESULTS: Sixty-five patients (28%) had at least 1 vertebral deformity and 25 (11%) had 2 or more vertebral deformities. Older age, independent of BMD, was a significant risk factor for deformity. Patients aged 70 to 79 years had a 5-fold increased risk of deformity compared with patients younger than 60 years (odds ratio, 5.13; 95% confidence interval, 2.03-13.0). Compared with the population controls, the prevalence of deformities increased to a greater extent with each decade of age in the corticosteroid group (P =.005). Mean lumbar spine and femoral neck BMD Z scores were lower in the steroid-treated patients with deformities compared with the nonsteroid control group with deformities. When the effects of age, sex, body mass index, and duration of corticosteroid use were adjusted for in logistic regression analysis, low BMD was a modest predictor of deformity (for a 1-SD decrease in lumbar spine BMD: odds ratio, 1.31; 95% confidence interval, 1.02-1.68) and for a 1-SD decrease in femoral neck BMD: odds ratio, 1.77; 95% confidence interval, 1.07-2.94). CONCLUSIONS: The combination of increasing age and corticosteroid use is associated with a marked increase in the risk of vertebral deformity. Elderly patients commencing long-term corticosteroid therapy should be considered for antiosteoporotic therapy independently of their BMD. Arch Intern Med. 2000;160:2917-2922

Age Factors↗
PubMed2000

Two double-blinded, randomized, comparative trials of 4 human immunodeficiency virus type 1 (HIV-1) envelope vaccines in HIV-1-infected individuals across a spectrum of disease severity: AIDS Clinical Trials Groups 209 and 214.

The potential role of human immunodeficiency virus type 1 (HIV-1)-specific immune responses in controlling viral replication in vivo has stimulated interest in enhancing virus-specific immunity by vaccinating infected individuals with HIV-1 or its components. These studies were undertaken to define patient populations most likely to respond to vaccination, with the induction of novel HIV-1-specific cellular immune responses, and to compare the safety and immunogenicity of several candidate recombinant HIV-1 envelope vaccines and adjuvants. New lymphoproliferative responses (LPRs) developed in <30% of vaccine recipients. LPRs were elicited primarily in study participants with a CD4 cell count >350 cells/mm(3) and were usually strain restricted. Responders tended to be more likely than nonresponders to have an undetectable level of HIV-1 RNA at baseline (P=.067). Induction of new cellular immune responses by HIV-1 envelope vaccines is a function of the immunologic stage of disease and baseline plasma HIV-1 RNA level and exhibits considerable vaccine strain specificity.

AIDS Vaccines↗
PubMed2000

Moth hearing in response to bat echolocation calls manipulated independently in time and frequency.

We measured the auditory responses of the noctuid moth Noctua pronuba to bat echolocation calls which were manipulated independently in time and frequency. Such manipulations are important in understanding how insect hearing influences the evolution of echolocation call characteristics. We manipulated the calls of three bat species (Rhinolophus hipposideros, Myotis nattereri and Pipistrellus pipistrellus) that use different echolocation call features by doubling their duration or reducing their frequency, and measured the auditory thresholds from the A1 cells of the moths. Knowing the auditory responses of the moth we tested three predictions. (i) The ranking of the audibility of unmanipulated calls to the moths should be predictable from their temporal and/or frequency structure. This was supported. (ii) Doubling the duration of the calls should increase their audibility by ca. 3 dB for all species. Their audibility did indeed increase by 2.1-3.5 dB. (iii) Reducing the frequency of the calls would increase their audibility for all species. Reducing the frequency had small effects for the two bat species which used short duration (2.7-3.6 ms) calls. However, the relatively long-duration (50 ms), largely constant-frequency calls of R. hipposideros increased in audibility by 21.6 dB when their frequency was halved. Time and frequency changes influence the audibility of calls to tympanate moths in different ways according to call design. Large changes in frequency and time had relatively small changes on the audibility of calls for short, largely broadband calls. Channelling energy into the second harmonic of the call substantially decreased the audibility of calls for bats which use long-duration, constant-frequency components in echolocation calls. We discuss our findings in the contexts of the evolution of both bat echolocation call design and the potential responses of insects which hear ultrasound.

Animals↗
PubMed2000

Deterin, a new inhibitor of apoptosis from Drosophila melanogaster.

Deterin, a new apoptosis inhibitor from Drosophila melanogaster, possesses an unusual structure of only a single baculovirus inhibitor of apoptosis (IAP)-type repeat and no RING finger motif. The biochemical actions of deterin are demonstrated in SF9 and S2 cell transfection assays, in which the expressed protein acts in the cytoplasm to inhibit or deter cells from apoptosis otherwise induced by the caspase-dependent apoptosis activator reaper or by cytotoxicants. A loss of function phenotype for deterin of cell death was indicated by transfections with either a dominant negative deterin mutant or with inhibitory RNA (RNAi) for deterin. The dominant negative C-terminal fragment that antagonized antiapoptotic activity of deterin did not affect antiapoptotic activity of DIAP1 or p35. Both the baculovirus IAP-type repeat (BIR) domain and the alpha-helical C-terminal domain are necessary in both SF9 and S2 cells for deterin to manifest its activity to prevent cell death. The approximately 650-base deterin transcript is present in embryos, third instar larvae, and late stage nurse cells of adult females. The deterin transcript is distributed throughout early stage embryos, whereas in later stage embryos it becomes progressively restricted to the central nervous system and gonads. Whereas the nematode survivin-type IAP has thus far been implicated only as a mitotic regulator, Drosophila deterin constitutes the first invertebrate member of the survivin-type IAP group to exhibit apoptosis-inhibitory activity.

Amino Acid Sequence↗
PubMed2000

Identification of the human cytochrome P450, P450RAI-2, which is predominantly expressed in the adult cerebellum and is responsible for all-trans-retinoic acid metabolism.

Retinoids, particularly all-trans-retinoic acid (RA), are potent regulators of cell differentiation, cell proliferation, and apoptosis. The role of all-trans-RA during development and in the maintenance of adult tissues has been well established. The control of all-trans-RA levels in cells and tissues is regulated by the balance between its biosynthesis and its catabolism to inactive metabolites. The cytochrome P450 enzyme P450RAI (herein renamed P450RAI-1) is partially responsible for this inactivation of all-trans-RA. In this report, we describe the identification, molecular cloning, and characterization of a second related enzyme, P450RAI-2, which is also involved in the specific inactivation of all-trans-RA. Transiently transfected P450RAI-2 can convert all-trans-RA to more polar metabolites including 4-oxo-, 4-OH-, and 18-OH-all-trans-RA. Competition experiments with other retinoids suggest that all-trans-RA is the preferred substrate. The high level of expression of P450RAI-2, particularly in the cerebellum and pons of human adult brain, suggests a unique role for this enzyme in the protection of specific tissues from exposure to retinoids.

Amino Acid Sequence↗
PubMed2000

Distinctive structural and kinetic properties of an unusual juvenile hormone-hydrolyzing esterase.

The insect juvenile hormone specific esterases (JHEs), related to acetylcholinesterases but exhibiting substrate specificity for juvenile hormone (JH), are essential enzymes for normal insect development, making them attractive targets for biorationally designed, environmentally safe pesticides. We examine here a new enzyme, JHER, related to, but yet structurally, biochemically, and kinetically distinct from, the classical JHE. Both classical JHE and baculovirus-expressed JHER hydrolyze JH show disproportionately higher catalytic rates at higher substrate concentrations (in contrast to substrate inhibition reported for acetylcholinesterase) and are similarly inhibited by an organophosphate. However, JHER, which possesses an unusual cysteine residue at +1 to the catalytic serine, is less sensitive to trifluoromethyl ketone transition state analogs designed around the structure of JH. We propose a model in which JHER is expressed just prior to metamorphosis for hydrolysis of a JH-like substrate with hydrophobic backbone, a proximal ester, and a terminal expoxide or related substitution.

Amino Acid Sequence↗
PubMed2000

Parentage, reproductive success and breeding behaviour in the greater horseshoe bat (Rhinolophus ferrumequinum).

Female greater horseshoe bats form maternity colonies each summer in order to give birth and raise young. During the mating period, females visit males occupying territorial sites, copulation takes place and sperm are stored until ovulation occurs, normally in April. Using microsatellite markers and a likelihood method of parentage analysis, we studied breeding behaviour and male reproductive success over a five-year period in a population of bats in south-west Britain. Paternity was assigned with 80% confidence to 44% of young born in five successive cohorts. While a small annual skew in male reproductive success was detected, the variance increased over five years due to the repeated success of a few individuals. Mating was polygynous, although some females gave birth to offspring sired by the same male in separate years. Such repeated partnerships probably result from fidelity for either mating sites or individuals or from sperm competition. Females mated with males born both within and outside their own natal colony; however, relatedness between parents was no less than the average recorded for male female pairs. Gene flow between colonies is likely to be primarily mediated by both female and male dispersal during the mating period rather than more permanent movements.

Animals↗
PubMed2000

Contribution of several metabolites of the vitamin D analog 20-epi-22-oxa-24a,26a,27a-tri-homo-1,25-(OH)(2) vitamin D(3) (KH 1060) to the overall biological activity of KH1060 by a shared mechanism of action.

The synthetic 1,25-dihydroxyvitamin D(3) (1,25-(OH)(2)D(3)) analog 20-epi-22-oxa-24a,26a,27a-tri-homo-1,25-(OH)(2)vitamin D(3) (KH1060) is considerably more potent than its cognate hormone. The mechanism of action of KH1060 includes interaction with the vitamin D receptor (VDR). We previously showed that KH1060 increases VDR stability in ROS 17/2.8 osteoblastic cells by inducing a specific conformational change in the VDR. KH1060 is metabolized, both in vivo and in vitro, into several stable products. In the present study, we investigated whether these metabolites might contribute to the increased biological activity of KH1060. We found that the potencies of two of these metabolites, 24a-OH-KH1060 and 26-OH-KH1060, were similar to that of 1,25-(OH)(2)D(3) in inducing osteocalcin production by the osteoblast cell line ROS 17/2.8. This report further showed that these metabolites had the same effects as KH1060 on VDR: they increased VDR stability in ROS 17/2.8 cells, while limited proteolytic analysis revealed that they caused a conformational change in the VDR, resulting in an increased resistance against proteolytic cleavage. Furthermore, as shown in gel mobility shift assays, both compounds clearly induced VDR binding to vitamin D response elements. Together, these results show that the potent in vitro activity of KH1060 is not only directed by the effects on the VDR conformation/stabilization of the analog itself, but also by certain of its long-lived metabolites, and emphasizes the importance of detailed knowledge of the metabolism of synthetic hormonal analogs.

Animals↗
PubMed2000

Serine and glycine transport in fetal ovine hepatocytes.

The role of hepatic serine and glycine transport in the regulation of the biosynthesis of serine by the fetal liver has not been studied. The goal of this study was to characterize serine and glycine transport and utilization at physiologic concentrations in primary cultures of fetal ovine hepatocytes. Primary culture of hepatocytes from mid gestation ( approximately 90 days) and term ( approximately 135 days) fetal sheep were studied after overnight serum free culture. At both gestational ages, the initial rate for sodium dependent 300 microM serine transport (1697+/-131 pmoles/min/mg protein at mid, 1765+/-544 at term) was fourfold greater than sodium dependent 300 microM glycine transport (309+/-54 at mid, 579+/-252 at term). At physiologic concentrations (300 microM), 69+/-7% of serine and 49+/-8% of glycine transport was sodium dependent. At term, sodium dependent serine transport has a V(max) of 1751+/-348 pmoles/min/mg protein and a K(m) of 159+/-111 microM. Sodium independent serine transport has a V(max) of 904+/-185 and a K(m) of 416+/-188 microM. Sodium dependent glycine transport has a V(max) of 410+/-69 and a K(m) of 2290+/-895 microM while sodium independent glycine transport exhibits non-saturable kinetics. Glycine (300 microM) sodium dependent transport was not inhibited by methyl-AIB while sodium dependent 300 microM serine transport was inhibited (31%). n-Ethylmaleimide inhibited sodium dependent serine and glycine transport by 36+/-9% and 37+/-2% respectively in term hepatocytes. Cysteine inhibited sodium dependent serine transport by 37%. Sodium independent glycine transport at 300 microM was higher in low glucose (1.1 mM) medium (881+/-76 pmoles/min/mg protein) compared to high glucose (5.5 mM) medium (510+/-60 P=0.004). There were no significant differences in serine or glycine incorporation into RNA, DNA, glycogen or lipid and protein. The predominance of serine transport over glycine at physiologic concentrations suggests that inward cellular amino acid transport of serine and glycine is not likely to be a regulatory mechanism that would favor serine biosynthesis in fetal ovine hepatocytes.

Animals↗
PubMed2000

Regulation of the juvenile hormone esterase gene by a composite core promoter.

Transcription from the core promoter of the juvenile hormone esterase gene (-61 to +28) requires the presence of both an AT-rich motif (TATA box) and an initiator motif for any transcription to occur, when assayed by either transcription in vitro with lepidopteran Sf9 nuclear extracts or by transient-transfection assay in Sf9 cells. Additional gel-shift experiments indicated that at least one additional binding site is essential for transcription to occur. Mutational analysis in the transcription-in vitro and cell-transfection assays demonstrated that a 14-bp region from +13 to +27 relative to the transcription start site is also essential for transcription to occur. Whereas the wild-type core promoter is highly transcriptionally active, inclusion of additional flanking sequences to position -212 reduces that activity approx. 100-fold, and inclusion of the 5' region out to position -500 reduces transcription by 200-fold. The pattern of dependence on both the AT-rich motif and the initiator for detectable transcription, and the high innate activity being repressed by 5'-binding factors, was recapitulated in mosquito C7-10 cells. This study demonstrates that the cellular juvenile hormone esterase gene is organized as a composite core promoter, dependent on both TATA-box and initiator-binding factors, an organization that has been more commonly reported for viral promoters. This highly active composite core promoter is made more complex by the absolute dependence on the presence of a third site shortly downstream from the initiator, which is distinct from the 'downstream promoter element' described from some TATA-less genes. The juvenile hormone esterase gene thus appears to be a model of a cellular composite core promoter with a multipartite, indispensible requirement for not just both the TATA box and initiator, but also for at least a third core element as well.

Animals↗
PubMed2000

A phase I trial in HIV negative healthy volunteers evaluating the effect of potent adjuvants on immunogenicity of a recombinant gp120W61D derived from dual tropic R5X4 HIV-1ACH320.

Thirty healthy HIV negative volunteers were randomised to receive 200 micrograms of rgp120W61D in either: 3D-MPL and QS21, with an oil and water emulsion (SBAS-2) (13); or 3D-MPL and QS21 (SBAS-1) (11); or alum (six). Immunizations were given at 0, 4 and 28 weeks and 23 (77%) participants completed the schedule. Adverse events were more frequent (P < 0.001) and more severe (P < 0.001) in the SBAS-2 group. Binding antibodies to the homologous rgp120W61D were detected after the first immunisation only in those receiving SBAS-1 and SBAS-2, were maximal after the third immunization in all three groups, and persisted to week 84 only in the novel adjuvant groups. These differences were significant (p = 0.02). Neutralising antibodies to TCLA-strains of HIV-1 were observed after the second immunization in all three groups, were maximal after the third immunization, but did not neutralise homologous or heterologous PBMC derived primary HIV-1 isolates. Proliferative T-cell responses to rgp120W61D were maximal after the second immunization and reached very high values in the SBAS-2 group. HIV-1 specific CD8+ MHC Class I restricted cytotoxic T-lymphocytes were not seen in a subset of participants tested at a single timepoint. SBAS-2 with rgp120W61D induced antibody titres as high as those seen in HIV infection, but the quality of the antibodies remained different in that there was no evidence of primary isolate neutralisation. Although cell-mediated immunity was enhanced by SBAS-2 in terms of lymphoproliferative responses, HIV-1 specific CD8+ cytotoxicity was not demonstrated.

AIDS Vaccines↗
PubMed2000

Interventions for psoriatic arthritis.

OBJECTIVES: To assess the effects of salazopyrin, auranofin, etretinate, fumaric acid, IMI gold, azathioprine, and methotrexate, in psoriatic arthritis. SEARCH STRATEGY: We searched Medline up to 1995, and Excerpta Medica (June 1974-95). Search terms were psoriasis, arthritis, therapy and/or controlled trial. This was supplemented by manually searching bibliographies of previously published reviews, conference proceedings and contacting drug companies. All languages were included in the initial search. SELECTION CRITERIA: All randomized trials comparing salazopyrin, auranofin, etretinate, fumaric acid, IMI gold, azathioprine, and methotrexate, in psoriatic arthritis. The main outcome measures included individual component variables derived from Outcome Measures in Rheumatology Clinical Trials (OMERACT). These include Acute Phase Reactants, Disability, Pain, Patient Global Assessment, Physician Global Assessment, Swollen joint count, Tender joint count and radiographic changes of joints in any trial of 1 year or longer [Tugwell 1993], and the change in pooled disease index. Only English trials were included in the review. DATA COLLECTION AND ANALYSIS: Data were independently extracted from the published reports by two of the reviewers. An independent blinded quality assessment was also performed. MAIN RESULTS: Nineteen randomized trials were identified of which eleven were included in the quantitative analysis with data from 777 subjects. Although all agents were better than placebo, parenteral high dose methotrexate (not included), salazopyrin, azathioprine and etretinate were the agents that achieved statistical significance in a global index of disease activity (although it should be noted that only one component variable was available for azathioprine and only one trial was available for etretinate suggesting some caution is necessary in interpreting these results). Analysis of response in individual disease activity markers was more variable with considerable differences between different medications and responses. In all trials the placebo group improved over baseline (pooled improvement 0.43 DI units, 95% CI 0. 28-0.59). There was insufficient data to examine toxicity. REVIEWER'S CONCLUSIONS: Parenteral high dose methotrexate and salazopyrin are the only two agents with well demonstrated published efficacy in psoriatic arthritis. The magnitude of the effect seen with azathioprine, etretinate, oral low dose methotrexate and perhaps colchicine suggests that they may be effective but that further multicentre clinical trials are required to establish their efficacy. Furthermore, the magnitude of the improvement observed in the placebo group strongly suggests that uncontrolled trials should not be used to guide management decisions in this condition.

Antirheumatic Agents↗
PubMed2000

Sex and site differences in cartilage development: a possible explanation for variations in knee osteoarthritis in later life.

OBJECTIVE: To test the hypothesis that sex-related and joint compartment-related differences in the risk of osteoarthritis (OA) of the knee might be associated with variations in cartilage development, we investigated knee cartilage volume in healthy children. METHODS: We studied 92 children who were randomly selected from among students in grades 3-12 of a single school in Hobart, Tasmania (49 boys, 43 girls; age range 9-18 years). Articular cartilage thickness and volume were determined at the patella, medial tibial compartment, and lateral tibial compartment by magnetic resonance imaging (MRI). Sagittal T1-weighted fat-suppressed MRI images were obtained and processed on an independent computer work station. RESULTS: Males had significantly more knee cartilage than females. Sex accounted for 6-36% of the variation in cartilage thickness and volume, which was statistically significant at all sites. Even after adjustment for age, body mass index, bone area, and physical activity, males had 16-31% higher cartilage volume; this was most marked at the medial tibial site. In addition, lateral tibial thickness was greater than medial tibial thickness (5.9 versus 3.6 mm; P < 0.0001) and lateral tibial volume was greater than medial tibial volume (2,823 versus 2,299 microl; P < 0.0001). Furthermore, physical activity was a significant explanatory factor for cartilage volume at all sites (R2 7-14% depending on site; all P < 0.05). The most consistent activity association was with vigorous activity in the previous 2 weeks (difference between any vigorous activity versus none 22-25% greater; all P < 0.05). CONCLUSION: Sex- and joint compartment-related differences in cartilage development may be one explanation for variations in the pattern of knee OA seen in later life. Furthermore, the physical activity associations suggest that cartilage development is amenable to modification.

Adolescent↗
PubMed2000

Myeloma proteins that bind Hsp65 (GroEL) are polyreactive and are found in high incidence in pristine induced plasmacytomas.

The myeloma proteins produced by 44 plasmacytomas (PCTs) recently induced by pristane in BALB/cAnPt and closely related PCT susceptible congenic strains of mice were isolated chromatographically and screened against a panel of 10 protein, nucleic acid and lipid antigens. This sample was highly unusual because 82% of the proteins had IgG isotopes. Nine of the proteins bound to Hsp65 (GroEL), and all of these were polyreactative. Twenty-one of the myeloma proteins were polyreactive and bound two or more antigens in the panel, and five were monoreactive. Thus, an antigen binding activity was determined for 59% of these myeloma proteins.

Animals↗
PubMed2000

Breastfeeding in early life and bone mass in prepubertal children: a longitudinal study.

The aim of this study was to determine whether breastfeeding in early life is associated with bone mass in prepubertal children. We studied 330 8-year-old male and female children from Southern Tasmania representing 47% of those who originally took part in a birth cohort study of risk factors for Sudden Infant Death Syndrome in 1988. Breastfeeding intention and habit were assessed in both 1988 and 1996. Bone mineral density was measured by dual-energy X-ray densitometry. Children who were breastfed had higher bone mineral density at the femoral neck (+0.20 SD, p = 0.07), lumbar spine (+0.25 SD, p = 0.03) and total body (+0.29 SD, p = 0.006) compared with those who were bottle-fed. This association with breastfeeding was present in children born at term (femoral neck: +0.26 SD, p = 0.05; lumbar spine: +0.34 SD, p = 0.007; total body: +0.41 SD, p = 0.0008) but not those born preterm, and remained significant after adjustment for size, lifestyle factors and socioeconomic factors. Breastfeeding for less than 3 months was not associated with increased bone mass at any site. In conclusion, this study has demonstrated a beneficial association between breastfeeding in early life and bone mass in 8-year-old children born at term, particularly those breastfed for 3 months or longer, which appears biological. If this association is confirmed in other populations and persists until the attainment of peak bone mass then the implication would be that osteoporosis prevention programs need to start very early in the life cycle.

Analysis of Variance↗