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Biomedical subjects

Susan Smith

Publications and source records attributed to Susan Smith.

At least 19 recordsLinked to original sources
PubMed2005

Comparative spatial and temporal localisation of perlecan, aggrecan and type I, II and IV collagen in the ovine meniscus: an ageing study.

This is the first study to immunolocalise perlecan in meniscal tissues and to demonstrate how its localisation varied with ageing relative to aggrecan and type I, II and IV collagen. Perlecan was present in the middle and inner meniscal zones where it was expressed by cells of an oval or rounded morphology. Unlike the other components visualised in this study, perlecan was strongly cell associated and its levels fell significantly with age onset and cell number decline. The peripheral outer meniscal zones displayed very little perlecan staining other than in small blood vessels. Picrosirius red staining viewed under polarised light strongly delineated complex arrangements of slender discrete randomly oriented collagen fibre bundles as well as transverse, thick, strongly oriented, collagen tie bundles in the middle and outer meniscal zones. The collagen fibres demarcated areas of the meniscus which were rich in anionic toluidine blue positive proteoglycans; immunolocalisations confirmed the presence of aggrecan and perlecan. When meniscal sections were examined macroscopically, type II collagen localisation in the inner meniscal zone was readily evident in the 2- to 7-day-old specimens; this became more disperse in the older meniscal specimens. Type I collagen had a widespread distribution in all meniscal zones at all time points. Type IV collagen was strongly associated with blood vessels in the 2- to 7-day-old meniscal specimens but was virtually undetectable at the later time points (>7 month).

Aggrecans↗
PubMed2005

NuMA is a major acceptor of poly(ADP-ribosyl)ation by tankyrase 1 in mitosis.

Tankyrase 1 is a PARP [poly(ADP-ribose) polymerase] that localizes to multiple subcellular sites, including telomeres and mitotic centrosomes. Previous studies demonstrated that cells deficient in tankyrase 1 suffered a block in resolution of sister telomeres and arrested in early anaphase [Dynek and Smith (2004) Science 304, 97-100]. This phenotype was dependent on the catalytic PARP activity of tankyrase 1. To identify critical acceptors of PARsylation [poly(ADP-ribosyl)ation] by tankyrase 1 in mitosis, tankyrase 1 immunoprecipitates were analysed for associated PARsylated proteins. We identified NuMA (nuclear mitotic apparatus protein) as a major acceptor of poly(ADP-ribose) from tankyrase 1 in mitosis. We showed by immunofluorescence and immunoprecipitation that association between tankyrase 1 and NuMA increases dramatically at the onset of mitosis, concomitant with PARsylation of NuMA. Knockdown of tankyrase 1 by siRNA (small interfering RNA) eliminates PARsylation of NuMA in mitosis, confirming tankyrase 1 as the PARP responsible for this modification. However, even in the absence of tankyrase 1 and PARsylation, NuMA localizes to spindle poles. By contrast, siRNA knockdown of NuMA results in complete loss of tankyrase 1 from spindle poles. We discuss our result in terms of a model where PARsylation of NuMA by tankyrase 1 in mitosis could play a role in sister telomere separation and/or mitotic progression.

Antigens, Nuclear↗
PubMed2005

Perlecan displays variable spatial and temporal immunolocalisation patterns in the articular and growth plate cartilages of the ovine stifle joint.

Perlecan is a modular heparan sulphate and/or chondroitin sulphate substituted proteoglycan of basement membrane, vascular tissues and cartilage. Perlecan acts as a low affinity co-receptor for fibroblast growth factors 1, 2, 7, 9, binds connective tissue growth factor and co-ordinates chondrogenesis, endochondral ossification and vascular remodelling during skeletal development; however, relatively little is known of its distribution in these tissues during ageing and development. The aim of the present study was to immunolocalise perlecan in the articular and epiphyseal growth plate cartilages of stifle joints in 2-day to 8-year-old pedigree merino sheep. Perlecan was prominent pericellularly in the stifle joint cartilages at all age points and also present in the inter-territorial matrix of the newborn to 19-month-old cartilage specimens. Aggrecan was part pericellular, but predominantly an extracellular proteoglycan. Perlecan was a prominent component of the long bone growth plates and displayed a pericellular as well as a strong ECM distribution pattern; this may indicate a so far unrecognised role for perlecan in the mineralisation of hypertrophic cartilage. A significant age dependant decline in cell number and perlecan levels was evident in the hyaline and growth plate cartilages. The prominent pericellular distribution of perlecan observed indicates potential roles in cell-matrix communication in cartilage, consistent with growth factor signalling, cellular proliferation and tissue development.

Aggrecans↗
PubMed2005

A randomized, placebo-controlled, double-masked clinical trial of etanercept for the treatment of uveitis associated with juvenile idiopathic arthritis.

OBJECTIVE: To investigate the safety and efficacy of etanercept in the treatment of uveitis associated with juvenile idiopathic arthritis (JIA). METHODS: Children who met the American College of Rheumatology diagnostic criteria for JIA with active uveitis, who had anterior chamber cells of >/=1+ or requiring topical corticosteroid >/=3 times daily, and who were on a stable regimen for arthritis treatment were eligible. Study participants received etanercept (0.4 mg/kg) or placebo administered subcutaneously twice weekly for 6 months. All participants received open-label etanercept for an additional 6 months. RESULTS: Five patients received placebo and 7 received etanercept. Three of the 7 patients treated with etanercept and 2 of the 5 placebo-treated patients were considered ophthalmic successes (P = 1.0). One patient in each treatment group was considered a treatment failure. Three of the 7 etanercept-treated and 2 of the 5 placebo-treated patients were neither successes nor failures by our definition. There were no serious adverse events for any patient during the entire study period. Reports of minor infections were comparable in each treatment group, 71% for etanercept and 60% for placebo (P = 0.58). CONCLUSION: In this small pilot study there was no apparent difference in the anterior segment inflammation between patients treated with etanercept and placebo. The stringent criteria used to measure ophthalmic success of treatment and the small patient population limit the implications of our findings.

Adolescent↗
PubMed2005

The effects of journaling for women with newly diagnosed breast cancer.

Forty-three women newly diagnosed with breast cancer participated in this study, which examined the role of expressive journal writing characteristics on mood over the course of a 12-week support group. Writing was analyzed using the linguistic inquiry and word count program. Writing characteristics that were examined included: average word count, number of journal entries, positive and negative emotion words, the ratio of positive to negative words, and the use of cognitive mechanism words (i.e. insight and causal words). Regression analyses revealed that increased levels of anxiety and depression, post-intervention, were predicted by the prevalence of negative emotion in writing. Unique variance in mood (anxiety and depression) was accounted for by expression of negative emotion (7 and 6%, respectively). These relationships were significant (p<0.05) and remained significant even after accounting for pre-intervention levels of distress, and for the quantity and frequency of writing. These findings suggest the need for additional research into the naturalistic application of journaling so that appropriate recommendations for writing (e.g. focus, timing, amount) can be offered to patients who might choose to utilize this approach for coping with the stresses of cancer diagnosis and treatment.

Adaptation, Psychological↗
PubMed2005

Differences in self-report measures by adolescent sex offender risk group.

Differences in self-reports among three groups of juvenile sex offenders (N = 162) were examined. Risk was defined as the sum of the following static variables based on interviews with juveniles and others and from written records: type of offense (violent or predatory = 1, not = 0), prior sex offense (any = 1, none = 0), history of sexual abuse (self or family = 1, none = 0), history of substance abuse (self or family = 1, none = 0), history of behavior problems (yes = 1, no = 0), and unstable home life (yes = 1, stable = 0). Low-risk (0 to 2 risk factors), medium-risk (3 factors), and high-risk (4 to 6 factors) groups of offenders were formed. Univariate ANCOVAs indicated that the high-risk group reported less family cohesion, more aggression, lower self-esteem, more social discomfort, and more frequent and extreme sexual fantasies. The implications of these findings for differential identification of and interventions with adolescent sex offenders are discussed.

Adolescent↗
PubMed2005

Adult genital surgery for intersex: a solution to what problem?

The desirability of routine genital surgery for infants with ambiguous genitalia is increasingly debated. But there is less discussion about intersex adults who choose genital surgery, despite evidence suggesting that the results are often unsatisfactory. This study reports on how six women with intersex conditions decided to have feminizing genital surgery and how they evaluated the outcomes. The initial analysis highlighted a chronological transition from surgery as nondilemmatic to surgery as a serious dilemma; a version of Foucauldian discourse analysis was then used to place the women's experiences in a cultural context. The implications for psychological involvement in services for women with intersex conditions are discussed.

Adult↗
PubMed2004

A dynamic molecular link between the telomere length regulator TRF1 and the chromosome end protector TRF2.

BACKGROUND: Human telomeres are coated by the telomere repeat binding proteins TRF1 and TRF2, which are believed to function independently to regulate telomere length and protect chromosome ends, respectively. RESULTS: Here, we show that TRF1 and TRF2 are linked via TIN2, a previously identified TRF1-interacting protein, and its novel binding partner TINT1. TINT1 localized to telomeres via TIN2, where it functioned as a negative regulator of telomerase-mediated telomere elongation. TIN2 associated with TINT1, and TRF1 or TRF2 throughout the cell cycle, revealing a partially redundant unit in telomeric chromatin that may provide flexibility in telomere length control. Indeed, when TRF1 was removed from telomeres by overexpression of the positive telomere length regulator tankyrase 1, the TIN2/TINT1 complex remained on telomeres via an increased association with TRF2. CONCLUSIONS: Our findings suggest a dynamic cross talk between TRF1 and TRF2 and provide a molecular mechanism for telomere length homeostasis by TRF2 in the absence of TRF1.

Base Sequence↗
PubMed2004

Resolution of sister telomere association is required for progression through mitosis.

Cohesins keep sister chromatids associated from the time of their replication in S phase until the onset of anaphase. In vertebrate cells, two distinct pathways dissociate cohesins, one acts on chromosome arms and the other on centromeres. Here, we describe a third pathway that acts on telomeres. Knockdown of tankyrase 1, a telomeric poly(ADP-ribose) polymerase caused mitotic arrest. Chromosomes aligned normally on the metaphase plate but were unable to segregate. Sister chromatids separated at centromeres and arms but remained associated at telomeres, apparently through proteinaceous bridges. Thus, telomeres may require a unique tankyrase 1-dependent mechanism for sister chromatid resolution before anaphase.

Anaphase↗
PubMed2004

Treatment of AIDS related non-Hodgkin's lymphoma with combination mitoguazone dihydrochloride and low dose CHOP chemotherapy: results of a phase II study.

PURPOSE: To evaluate the response and side effects of combination therapy with low dose CHOP chemotherapy and mitoguazone dihydrochloride in patients with non-Hodgkin's lymphoma associated with the acquired immunodeficiency syndrome (AIDS-NHL). METHODS: Eighteen patients newly diagnosed with intermediate or high-grade AIDS-NHL were treated with low dose CHOP as follows: day 1, cyclophosphamide 350 mg/m(2), intravenously (IV); doxorubicin 25mg/m(2) IV; vincristine 2mg IV; and prednisone 100mg given orally on days 1 through 5. In addition, mitoguazone dihydrochloride was given at a dose of 600 mg/m(2) IV on days 1 and 15 of each 28-day treatment cycle. RESULTS: Seventeen males and one female patient were accrued. Twelve patients had high-grade pathologies while the remainder had an intermediate grade pathology (diffuse large cell). The median CD4+ lymphocyte count was 98/dl (range 1-924). Three patients (17%) reported an AIDS-defining illness prior to lymphoma diagnosis. Of 14 evaluable patients, 6 (43%) achieved a complete remission and 5 (35%) a partial remission. The median failure free and overall survival times were 6.5 and 8.4 months, respectively. Major toxicity was hematologic with grade 3 or 4 neutropenia in 72%; two patients died of neutropenic sepsis. CONCLUSIONS: Mitoguazone in combination with low dose CHOP is a safe regimen, associated with a response rate of 79% (CR 43%, PR 36%, 95% CI=49-95%). These preliminary results suggest no major improvement in terms of response over use of CHOP without mitoguazone.

Adult↗
PubMed2004

Functional subdomain in the ankyrin domain of tankyrase 1 required for poly(ADP-ribosyl)ation of TRF1 and telomere elongation.

In human cells, telomere elongation by telomerase is repressed in cis by the telomeric protein TRF1. Tankyrase 1 binds TRF1 via its ankyrin domain and poly(ADP-ribosyl)ates it. Overexpression of tankyrase 1 in telomerase-positive cells releases TRF1 from telomeres, resulting in telomere elongation. The tankyrase 1 ankyrin domain is classified into five conserved subdomains, ARCs (ankyrin repeat clusters) I to V. Here, we investigated the biological significance of the ARCs. First, each ARC worked as an independent binding site for TRF1. Second, ARCs II to V recognized the N-terminal acidic domain of TRF1 whereas ARC I bound a discrete site between the homodimerization and the Myb-like domains of TRF1. Inactivation of TRF1 binding in the C-terminal ARC, ARC V, either by deletion or point mutation, significantly reduced the ability of tankyrase 1 to poly(ADP-ribosyl)ate TRF1, release TRF1 from telomeres, and elongate telomeres. In contrast, other ARCs, ARC II and/or IV, inactivated by point mutations still retained the biological function of tankyrase 1. On the other hand, ARC V per se was not sufficient for telomere elongation, suggesting a structural role for multiple ARCs. This work provides evidence that specific ARC-TRF1 interactions play roles in the essential catalytic function of tankyrase 1.

Amino Acid Sequence↗
PubMed2004

Perlecan immunolocalizes to perichondrial vessels and canals in human fetal cartilaginous primordia in early vascular and matrix remodeling events associated with diarthrodial joint development.

The aim of this study was to ascertain how perlecan was localized in human fetal cartilaginous joint rudiment tissues. Perlecan was immunolocalized in human fetal (12-14-week-old) toe, finger, knee, elbow, shoulder, and hip joint rudiments using a monoclonal antibody to domain-1 of perlecan (MAb A76). Perlecan had a widespread distribution in the cartilaginous joint rudiments and growth plates and was also prominent in a network of convoluted hairpin loop-type vessels at the presumptive articulating surfaces of joints. Perlecan was also present in small perichondrial venules and arterioles along the shaft of the developing long bones, small blood vessels in the synovial lining and joint capsules, and in distinctive arrangements of cartilage canals in the knee, elbow, shoulder, and hip joint rudiments. Perlecan was notably absent from CD-31-positive metaphyseal vessels in the hip, knee, shoulder, and fingers. These vessels may have a role in the nutrition of the expanding cell populations in these developing joint tissues and in the establishment of the secondary centers of ossification in the long bones, which is essential for endochondral ossification.

Antibodies, Monoclonal↗
PubMed2004

Histological and immunohistological studies on cartilage.

The material properties of dense avascular connective tissues such as cartilage present unique challenges to the development of any prospective histological procedures. This chapter documents some of the protocols we have developed in our laboratories for the histological and immunohistochemical evaluation of extracellular-matrix components in normal and pathological articular cartilage. Illustrative examples are provided of specimens from an ovine meniscectomy model of osteoarthritis. A major strength of this experimental animal model is that spatial and temporal changes in joint matrix components can be followed longitudinally in an animal population of well-defined pedigree that minimizes biological variation. Furthermore, a systematic experimental approach can be adopted with this model using cartilage specimens from early predegenerative stages to later advanced stages of joint degeneration. Significantly, the histological changes observed in this model closely parallel changes evident in joint tissues during osteoarthritis in humans and have provided significant insights into these degenerative processes.

Animals↗
PubMed2004

Histochemical visualization of the cartilage hyaladherins using a biotinylated hyaluronan oligosaccharide bioaffinity probe.

Hyaluronan (HA) binding proteins (HABPs) were localized in cartilaginous ovine tissues (articular cartilage, intervertebral disc) using a biotinylated HA (bHA) oligosaccharide bioaffinity probe. The bHA oligosaccharide probe was prepared by partial digestion of HA with ovine testicular hyaluronidase, and the oligosaccharides were labeled with biotin hydrazide and purified by a combination of aggrecan G1 domain and avidin affinity chromatography. Hyaladherins were prominently visualized in tissue sections using the bHA oligosaccharide probe as pericellular components in hypertrophic epiphyseal and vertebral growth plate chondrocytes and in the enlarged cells of the cartilaginous end plate of the intervertebral disc. Weaker extracellular staining was also evident in the matrix of the ovine newborn hip and knee joint cartilages. The bHA oligosaccharide probe also visualized intracellular HABPs (IHABPs) in the hypertrophic growth plate chondrocytes of the primary ossification centers. Monolayer cultures of ovine chondrocytes rapidly internalized the bHA oligosaccharide affinity probe to discrete cytoplasmic, nuclear, and perinuclear regions, which were visualized by indirect fluorescent microscopy. This bHA oligosaccharide affinity probe may be useful in future investigations designed to characterize these novel cartilage IHABPs and the role that HA endocytosis plays in cellular regulatory processes in cartilage homeostasis.

Aggrecans↗