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L Smith

Publications and source records attributed to L Smith.

At least 55 records · Page 3Linked to original sources
PubMed2001

Delayed replication timing leads to delayed mitotic chromosome condensation and chromosomal instability of chromosome translocations.

Chromosomal rearrangements are found in virtually all types of human cancers. We show that certain chromosome translocations display a delay in mitotic chromosome condensation that is associated with a delay in the mitosis-specific phosphorylation of histone H3. This delay in mitotic condensation is preceded by a delay in both the initiation as well as the completion of chromosome replication. In addition, chromosomes with this phenotype participate in numerous secondary translocations and rearrangements. Chromosomes with this phenotype were detected in five of seven tumor-derived cell lines and in five of thirteen primary tumor samples. These data suggest that certain chromosomal rearrangements found in tumor cells cause a significant delay in replication timing of the entire chromosome that subsequently results in delayed mitotic chromosome condensation and ultimately in chromosomal instability.

Cell Line↗
PubMed2001

Coronary thermodilution to assess flow reserve: experimental validation.

BACKGROUND: Fractional flow reserve (FFR) and coronary flow reserve (CFR) are indices of coronary stenosis severity that provide the clinician with complementary information on the contribution of epicardial arteries and microcirculation to total resistance to myocardial blood flow. At present, FFR and CFR can only be obtained by 2 separate guidewires. The present study tested the validity of the thermodilution principle in assessing CFR with one pressure-temperature sensor-tipped guidewire. METHODS AND RESULTS: In an in vitro model, absolute flow was compared with the inverse mean transit time (1/T(mn)) of a thermodilution curve obtained after a bolus injection of 3 mL of saline at room temperature. A very close correlation (r>0.95) was found between absolute flow and 1/T(mn) when the sensor was placed >/=6 cm from the injection site. In 6 chronically instrumented dogs (60 stenoses; FFR from 0.19 to 0.98), a significant linear relation was found between flow velocity and 1/T(mn). A significant correlation was found between CFR(Doppler), which was calculated from the ratio of hyperemic to resting flow velocities, and CFR(thermo), which was calculated from the ratio of resting to hyperemic T(mn) (r=0.76; SEE=0.24; P<0.001). CONCLUSION: The present findings demonstrate the validity of the thermodilution principle to assess CFR. Because the pressure-temperature sensor was mounted in a commercially available angioplasty guidewire, this technique permits simultaneous measurements of CFR and FFR.

Animals↗
PubMed2001

Role of LXCXE motif-dependent interactions in the activity of the retinoblastoma protein.

Cell cycle control by pRb requires the integrity of the pocket domain, which is a region necessary for interactions with a variety of proteins, including E2F and LXCXE-motif containing proteins. Through knowledge of the crystal structure of pRb we have prepared a panel of pRb mutant derivatives in which a cluster of lysine residues that demark the LXCXE peptide binding domain were systematically mutated. One of the mutant derivatives, Rb6A, exhibits significantly reduced LXCXE-dependent interactions with HPV E7, cyclinD1 and HDAC2, but retained LXCXE-independent binding to E2F. Consistent with these results, Rb6A could down-regulate E2F-1-dependent activation of different E2F responsive promoters, but was compromised in Rb-dependent repression. Most importantly, Rb6A retained wild-type growth arrest activity, and colony forming activity similar to wild-type pRb. It is compatible with these results that directly targeting HDAC2 to E2F responsive promoters as an E2F/HDAC hybrid protein failed to effect cell cycle arrest. These results suggest that LXCXE-dependent interactions are not essential for pRb to exert growth arrest.

Amino Acid Motifs↗
PubMed2001

Myosin light chain kinase binding to a unique site on F-actin revealed by three-dimensional image reconstruction.

Ca2+-calmodulin-dependent phosphorylation of myosin regulatory light chains by the catalytic COOH-terminal half of myosin light chain kinase (MLCK) activates myosin II in smooth and nonmuscle cells. In addition, MLCK binds to thin filaments in situ and F-actin in vitro via a specific repeat motif in its NH2 terminus at a stoichiometry of one MLCK per three actin monomers. We have investigated the structural basis of MLCK-actin interactions by negative staining and helical reconstruction. F-actin was decorated with a peptide containing the NH2-terminal 147 residues of MLCK (MLCK-147) that binds to F-actin with high affinity. MLCK-147 caused formation of F-actin rafts, and single filaments within rafts were used for structural analysis. Three-dimensional reconstructions showed MLCK density on the extreme periphery of subdomain-1 of each actin monomer forming a bridge to the periphery of subdomain-4 of the azimuthally adjacent actin. Fitting the reconstruction to the atomic model of F-actin revealed interaction of MLCK-147 close to the COOH terminus of the first actin and near residues 228-232 of the second. This unique location enables MLCK to bind to actin without interfering with the binding of any other key actin-binding proteins, including myosin, tropomyosin, caldesmon, and calponin.

Actins↗
PubMed2001

[Prediction of IQ among children with birth weight under 1, 501 gms].

INTRODUCTION: As a group, preterm infants are at considerable risk of cognitive difficulties. However, predicting cognitive sequelae has proved to be difficult. The current study reports on prediction of IQ at age eight years on the basis of the children's perinatal and developmental status, as well as parental socioeconomic status. MATERIALS AND METHODS: The sample consisted of 104 infants with birth weight < or = 1,501 g (53 girls), recruited consecutively in the neonatal intensive care unit and followed up to age eight years. Perinatal status, early cognitive development, and parental socioeconomic status served as predictors. Cognitive ability assessed on two commonly used intelligence tests served as outcome. The participants did not represent a total population, and no control group was used. RESULTS: Regression analyses revealed that birth weight, the Bayley cognitive index at 39 and 56 weeks, and parental socioeconomic status all made significant and independent contributions to outcome. Though the Bayley index made no significant contribution at age 29 weeks, it was the only variable at age two that was related to IQ at age eight. INTERPRETATION: Perinatal data are generally of limited value for the prediction of later IQ among preterm infants. However, when combined with information about parental socioeconomic status and the infants' developmental status up to age 56 weeks, birth weight made a unique and significant contribution as a predictor of later IQ. At age two years the cognitive status of prematurely born children was sufficiently consolidated to yield a valid prediction of outcome.

Child↗
PubMed2001

Phase I and pharmacokinetic study of BMS-184476, a taxane with greater potency and solubility than paclitaxel.

PURPOSE: To assess the feasibility, toxicity, pharmacokinetics, and preliminary activity of BMS-184476 administered as a 1-hour intravenous (IV) infusion every 3 weeks. PATIENTS AND METHODS: Patients with advanced solid malignancies were treated with escalating doses of BMS-184476 as a 1-hour IV infusion every 3 weeks without premedication to prevent hypersensitivity reactions (HSR). Plasma sampling and urine collections were performed to characterize the pharmacokinetics and pharmacodynamics of BMS-184474. RESULTS: Thirty-four patients were treated with 78 courses of BMS-184476 at five dose levels ranging from 20 to 80 mg/m2. Dose-limiting toxicity (DLT), consisting of severe neutropenia with fever, severe diarrhea, and/or severe mucositis, was experienced during course 1 by six of nine minimally pretreated patients treated at the 70 and 80 mg/m2 dose level. In contrast, of 15 assessable patients treated at the 60 mg/m2 dose level, which is the maximum-tolerated dose (MTD) of BMS-184476 on this administration schedule, only one heavily pretreated patient developed DLT (grade 4 neutropenia with fever and grade 3 diarrhea). One patient developed a grade 2 HSR during a second course of BMS-184476 at the 40 mg/m2 dose level. A previously untreated patient with an advanced cholangiocarcinoma experienced a partial response, and a patient with an untreated carcinoma of the gastroesophageal junction had a minor response. The pharmacokinetics of BMS-184476 seemed linear in the dose range studied. Mean +/- SD values for clearance, volume of distribution at steady-state, and terminal half-life were 220 +/- 89 mL/min/m2, 402 +/- 231 L/m2, and 40.8 +/- 21.8 hours, respectively. CONCLUSION: The MTD and recommended dose for phase II evaluations of BMS-184476 is 60 mg/m2 as a 1-hour IV infusion every 3 weeks. The results of this study suggest that BMS-184476 may have several advantages compared with paclitaxel in terms of toxicity, pharmacokinetics, pharmaceutics, and administration and warrants further clinical development.

Adult↗
PubMed2001

Defined flanking spacers and enhanced proteolysis is essential for eradication of established tumors by an epitope string DNA vaccine.

Loss of immunogenic epitopes by tumors has urged the development of vaccines against multiple epitopes. Recombinant DNA technologies have opened the possibility to develop multiepitope vaccines in a relatively rapid and efficient way. We have constructed four naked DNA-based multiepitope vaccines, containing CTL, Th cell, and B cell epitopes of the human papillomavirus type 16. Here we show that gene gun-mediated vaccination with an epitope-based DNA vaccine protects 100% of the vaccinated mice against a lethal tumor challenge. The addition of spacers between the epitopes was crucial for the epitope-induced tumor protection, as the same DNA construct without spacers was significantly less effective and only protected 50% of the mice. When tested for therapeutic potential, only the epitope construct with defined spacers significantly reduced the size of established tumors, but failed to induce tumor regression. Only after targeting the vaccine-encoded protein to the protein degradation pathway by linking it to ubiquitin, the vaccine-induced T cell-mediated eradication of 100% of 7-day established tumors in mice. The finding that defined flanking sequences around epitopes and protein targeting dramatically increased the efficacy of epitope string DNA vaccines against established tumors will be of importance for the further development of multiepitope DNA vaccines toward clinical application.

Adjuvants, Immunologic↗
PubMed2001

Passive ozone network of Dallas: a modeling opportunity with community involvement. 1.

Despite tremendous efforts toward regulating and controlling tropospheric ozone (O3) formation, a large portion of the U.S. population presently lives in environments where air quality exceeds both 1- and 8-h National Ambient Air Quality Standards (NAAQS) set for O3. High O3 concentrations annually cost the United States billions of dollars in excessive human health costs, reduced crop yields, and ecological damage. This paper describes a regional networking of O3 monitoring sites, operated by the public, that used simplified passive sampling devices (PSDs). In collaboration with EPA Region 6, a lay network (i.e., Passive Ozone Network of Dallas, acronym POND), consisting of 30 PSD sites in the Dallas-Fort Worth (DFW) Metroplex, a region representing 16 counties, successfully measured daily ozone during 8 weeks of the 1998 high ozone season. It was demonstrated that the concerned public, when properly trained, could successfully operate a large PSD network that requires daily sample handling and weekly mailing procedures, even from remote sites. Data treatment of the 2880 POND measurements included (i) high correlations with collocated continuous monitoring data [r range = 0.95-0.97], (ii) daily O3 contour mapping of the 24,000 km2 area, and (iii) a ranking of O3 severity in 12 peri-urban counties for guidance in sitting additional monitors. With a new 8-h NAAQS standard now in place, a cost-effective network such as POND could aid regional airshed models in generating meaningful guidance for O3 state implementation plans (SIPs) by providing input that is representative of both rural and urban sites.

Adult↗
PubMed2001

Fluorescence-based directed termination PCR: direct mutation characterization without sequencing.

We describe a fluorescence-based directed termination PCR (fluorescent DT-PCR) that allows accurate determination of actual sequence changes without dideoxy DNA sequencing. This is achieved using near infrared dye-labeled primers and performing two PCR reactions under low and unbalanced dNTP concentrations. Visualization of resulting termination fragments is accomplished with a dual dye Li-cor DNA sequencer. As each DT-PCR reaction generates two sets of terminating fragments, a pair of complementary reactions with limiting dATP and dCTP collectively provide information on the entire sequence of a target DNA, allowing an accurate determination of any base change. Blind analysis of 78 mutants of the supF reporter gene using fluorescent DT-PCR not only correctly determined the nature and position of all types of substitution mutations in the supF gene, but also allowed rapid scanning of the signature sequences among identical mutations. The method provides simplicity in the generation of terminating fragments and 100% accuracy in mutation characterization. Fluorescent DT-PCR was successfully used to generate a UV-induced spectrum of mutations in the supF gene following replication on a single plate of human DNA repair-deficient cells. We anticipate that the automated DT-PCR method will serve as a cost-effective alternative to dideoxy sequencing in studies involving large-scale analysis for nucleotide sequence changes.

Automation↗
PubMed2001

[Psychological status at 8-9 years of age in children with birth weight below 1,501 grams].

BACKGROUND: Studies have demonstrated that many children with low birth weight show signs of developmental disorders. Research and clinical experience indicate that gestational age is related to outcome. The aim of the present study was to investigate the differential outcome of children with gestational age < or = 28 weeks and those who were born later. MATERIAL AND METHODS: The sample consisted of 104 infants with birth weight < or = 1,500 g (53 girls) who were followed up to age eight years, with subsequent testing of school-related achievement at age nine years. Well-known instruments to identify developmental disorders and learning difficulties were used. RESULTS: The results showed that for the sample as a whole, AD/HD was the most prevalent disorder. There was a moderate degree of delay in intellectual development and of learning difficulties. In these areas there were significant differences in outcome in favour of the group with gestational age > 28 weeks. No significant sex differences were found, except in relation to mathematical skills, where boys performed better than girls. INTERPRETATION: As a group the children with very low birth weight had adequate intellectual and scholastic outcome. However, the prevalence of AD/HD was relatively high (27%). Low gestational age, but not dysmaturity, was associated with increased risk for poorer outcome.

Attention Deficit Disorder with Hyperactivity↗
PubMed2001

Reprogramming of telomerase activity and rebuilding of telomere length in cloned cattle.

Nuclear reprogramming requires the removal of epigenetic modifications imposed on the chromatin during cellular differentiation and division. The mammalian oocyte can reverse these alterations to a state of totipotency, allowing the production of viable cloned offspring from somatic cell nuclei. To determine whether nuclear reprogramming is complete in cloned animals, we assessed the telomerase activity and telomere length status in cloned embryos, fetuses, and newborn offspring derived from somatic cell nuclear transfer. In this report, we show that telomerase activity was significantly (P < 0.05) diminished in bovine fibroblast donor cells compared with embryonic stem-like cells, and surprisingly was 16-fold higher in fetal fibroblasts compared with adult fibroblasts (P < 0.05). Cell passaging and culture periods under serum starvation conditions significantly decreased telomerase activity by approximately 30-50% compared with nontreated early passage cells (P < 0.05). Telomere shortening was observed during in vitro culture of bovine fetal fibroblasts and in very late passages of embryonic stem-like cells. Reprogramming of telomerase activity was apparent by the blastocyst stage of postcloning embryonic development, and telomere lengths were longer (15-23 kb) in cloned fetuses and offspring than the relatively short mean terminal restriction fragment lengths (14-18 kb) observed in adult donor cells. Overall, telomere lengths of cloned fetuses and newborn calves ( approximately 20 kb) were not significantly different from those of age-matched control animals (P > 0.05). These results demonstrate that cloned embryos inherit genomic modifications acquired during the donor nuclei's in vivo and in vitro period but are subsequently reversed during development of the cloned animal.

Animals↗
PubMed2001

Non-invasive intravascular monitoring in the pediatric hemodialysis population.

Assessment of dry weight in pediatric hemodialysis (HD) patients is difficult, since small fluid shifts may result in dialysis-associated morbidity (DAM) and children may not verbalize complaints. Achieving dry weight is critical since chronic fluid overload can result in hypertension and left ventricular hypertrophy. To determine if non-invasive monitoring of hematocrit (NIVM) is useful in preventing DAM in pediatric HD patients, we reviewed 200 HD treatments performed with or without NIVM (no NIVM). DAM was defined as an "event" (e.g., hypotension, headache, cramping) that required nursing intervention. Patient age, weight, and gender were similar in both groups. Desired ultrafiltration was obtained in both groups. The event rate was lower in NIVM than no NIVM for all treatments (0.22 vs. 0.3, P = 0.07) and significantly lower in patients < 35 kg (0.25 vs. 0.47, P = 0.01). The second event rate (fraction of treatments with one event that had a subsequent event occurring at least 15 min later) was lower with NIVM (P < 0.01). For the NIVM group, events in the first 90 min occurred when blood volume changed > 8% per hour; 71% of events (43/60) at 90-240 min occurred when blood volume changed > 4% per hour. NIVM decreases DAM in pediatric HD patients, especially those < 35 kg. Ultrafiltration with blood volume change < 8% per hour is safe in the 1st h and < 4% after 1 h reduces DAM in children.

Adolescent↗
PubMed2001

High omega-3:omega-6 fatty acid ratios in culture medium reduce endometrial-cell survival in combined endometrial gland and stromal cell cultures from women with and without endometriosis.

OBJECTIVE: To study the effects of omega-3 and omega-6 polyunsaturated fatty acid (PUFA) on in vitro proliferation of endometrial cells and their production of the cytokine interleukin-8 (IL-8). DESIGN: In vitro study. SETTING: Obstetrics and gynecology department, University of Aberdeen. PATIENT(S): Women attending an infertility clinic. INTERVENTION(S): In vitro cell cultures using culture mediums supplemented with normal and high ratios of omega-3 PUFA and omega-6 PUFA. MAIN OUTCOME MEASURE(S): In vitro survival and production of IL-8 by dispersed endometrial cells. RESULT(S): In vitro survival of endometrial cells from women with and without endometriosis was significantly reduced in the presence of high omega-3:omega-6 PUFA ratios compared with cells incubated in the absence of fatty acids, in balanced omega-3:omega-6 PUFA ratios, and in high omega-6:omega-3 PUFA ratios. Endometrial cells from women with endometriosis secreted higher concentrations of IL-8, especially in the presence of high omega-3:omega-6 PUFA ratios. CONCLUSION(S): omega-3 PUFA may have a suppressive effect on the in vitro survival of endometrial cells and omega-3 PUFA be useful in the management of endometriosis by reducing the inflammatory response and modulating cytokine function.

Cell Survival↗
PubMed2001

Psychological, nutritional, and energy expenditure differences in college females with anorexia nervosa vs. comparable-mass controls.

This is the first study to examine psychological and behavioral variables in nonhospitalized college females with subclinical anorexia nervosa (AN) as compared to healthy college females of comparable body mass (i.e., body mass index (BMI)<19). Participants who met all DSM-IV [Diagnostic and statistical manual of mental disorders, 4th ed. (1994). Washington, DC: APA.] criteria for AN-restrictive type (except for BMI<17.5; n=11) and control participants (n=15) with comparable body mass completed psychological, nutritional, and exercise assessments. Results suggested that those with AN evidenced more general psychopathology, more eating disorder symptoms, more dieting, more compulsive exercise, and less consumption of calories compared to participants in the control group. There was no difference in macronutrient consumption. There was no significant difference in expenditure of energy, despite differences in reports of compulsive exercise. Given similar body mass, this suggests that the women with AN were experiencing an energy deficit consistent with the disorder's defining features of "fear of gaining weight or becoming fat" and provides us with more understanding of individuals with AN in their natural environment.

Journal Article↗
PubMed2001

Differential expression of the early lung cancer detection marker, heterogeneous nuclear ribonucleoprotein-A2/B1 (hnRNP-A2/B1) in normal breast and neoplastic breast cancer.

Heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNP-A2/B1) is highly expressed during critical stages of lung development and carcinogenesis. To determine if the expression of hnRNP-A2/B1 is an informative biomarker in breast carcinogenesis, we analyzed hnRNP-A2/B1 overexpression by immunohistochemistry in archived specimens. Expression was detected in 48/85 (56.5%) primary invasive breast cancers and 7/72 (9.7%) specimens of normal breast tissue. Northern analysis of breast cancer cells also demonstrated higher level of hnRNP-A2/B1 expression compared to normal or transformed breast cells. Expression of hnRNP-A2/B1 in breast cancer cells was decreased by exposure to retinoids coordinately with decreased cell growth. These results warrant further evaluation of hnRNP-A2/B1 as a marker of breast carcinogenesis.

Biomarkers, Tumor↗
PubMed2001

Acetylation control of the retinoblastoma tumour-suppressor protein.

The retinoblastoma tumour-suppressor protein (pRb) and p300/CBP co-activator proteins are important for control of proliferation and in tumour cells these are sequestered by viral oncoproteins such as E1A. pRb is involved in negatively regulating growth, and p300/CBP proteins have histone acetyltransferase (HAT) activity, which influences gene expression. Although it is known that phosphorylation by G1 cyclin-dependent kinases (CDKs) regulates pRb activity, the nature and role of other post-translational modifications is not understood. Here we identify acetylation as a new type of modification and level of control in pRb function. Adenovirus E1A, which binds p300/CBP through an amino-terminal transformation-sensitive domain, stimulates the acetylation of pRb by recruiting p300 and pRb into a multimeric-protein complex. Furthermore, pRb acetylation is under cell-cycle control, and acetylation hinders the phosphorylation of pRb by cyclin-dependent kinases. pRb binds more strongly when acetylated to the MDM2 oncoprotein, which indicates that acetylation may regulate protein-protein interactions in the pRb pathway. The acetylation of pRb defines a new level of cell-cycle control mediated by HAT. Furthermore, our results establish a relationship between p300, pRb and acetylation in which E1A acts to recruit and target a cellular HAT activity to pRb.

Acetylation↗
PubMed2001

Development of spontaneous factor VIII inhibitor in association with acute graft-versus-host disease.

A 57-year-old female with recurrent AML underwent a T cell-depleted (TCD) bone marrow (BM) plus TCD and CD34-selected peripheral blood stem cell (PBSC) transplant. Eleven weeks post transplantation, the patient developed acute graft-versus-host disease (GVHD) manifested by rash and elevated liver enzymes. Concurrently, the patient presented with a bleeding diathesis and a left forearm hematoma due to the development of a spontaneous factor VIII inhibitor. She was treated with human recombinant factor VIII and intravenous methylprednisolone. Subsequently she was managed with a prednisone taper leading to resolution of the GVHD, as well as the spontaneous factor VIII inhibitor. Bone marrow transplant-related spontaneous factor VIII inhibitor has previously been reported in association with one patient with chronic GVHD. To our knowledge this is the first report of spontaneous factor VIII inhibitor associated with acute GVHD.

Acute Disease↗