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Biomedical subjects

L Barber

Publications and source records attributed to L Barber.

At least 19 recordsLinked to original sources
PubMed2005

Lineage differentiation of canine lymphoma/leukemias and aberrant expression of CD molecules.

Multiparameter flow cytometry analysis and specific cluster differentiation (CD) molecules were used to determine the expression profiles of B- and T-cell antigens on lymph node preparations from 59 dogs with generalized or multisystemic lymphoma. Lymph node samples from 11 healthy dogs were labeled to validate the specificity of antibodies and to formulate guidelines for interpretation of the results obtained from lymphoma samples. In normal lymph nodes, T-lymphocytes expressing CD3, CD4, or CD8 beta represented 59+/-11%, 43+/-8%, or 16+/-5% of the total cells, whereas B-lymphocytes expressing either CD21 or surface IgM (IgM) represented 37+/-9% or 14+/-5%, respectively. Small lymphocytes could be distinguished from large lymphocytes by forward light scatter. Of the patient samples 29 different breeds were represented with Golden and Labrador retriever being the most common. The lymphoma samples segregated into three groups based on CD antigen expression. Thirty cases predominantly expressed one or more combinations of CD79a, IgM, and CD21 representing a B-cell lineage. Three B-cell cases also expressed the stem cell antigen, CD34. Sixteen cases expressed one or more combinations of CD3, CD4, and CD8 consistent with a T-cell lineage and CD3+CD4+CD8--phenotype was the most common. Thirteen cases showed a mixed expression profile for T- and B-cell antigens and in three cases CD14 was highly expressed. Clinical response was poorest for T-cell lymphomas. Leukemic states occurred in all three phenotypes; but mixed cell cases had the greatest proportion. Dual immunofluorescence staining confirmed co-expression of T-cell (CD3) and B-cell antigens (CD79a or CD21) on neoplastic lymphocytes of six mixed cell cases. In one mixed cell case, dual immunostaining identified lymphocyte populations that stained mutually exclusive for CD79a and CD3. Six mixed cell lymphomas tested by PCR showed clonality for rearranged antigen receptor. Four cases that were CD79a+CD3+ had TCRgamma chain gene rearrangements, whereas two cases that were CD3+CD8+CD21+ had Ig heavy chain rearrangement. One case expressing multiple CD molecules (CD3+CD8+CD21+CD14+) was PCR negative for both Ig and TCRgamma gene rearrangement and could not be classified into a B- or T-cell lineage. We show for the first time co-expression of B- and T-cell markers on lymphoma cells that had specific T- or B-cell gene rearrangements. These findings suggest that aberrant CD molecule expression is not an uncommon finding in canine lymphomas and is a useful diagnostic marker for malignancy.

Animals↗
PubMed2001

[Refractory hypotension sustained during general anesthesia due to chronic treatment with angiotensin-converting enzyme inhibitors].

Perioperative management of angiotensin-converting enzyme inhibitors (ACEI) is controversial because of associated hypertensive episodes during induction and maintenance of anesthesia. A 71-year-old woman with a non-functioning thyroid node was scheduled for thyroid lobectomy. Her medical history included high blood pressure and she was being chronically treated with ACEI, which were taken until the morning of surgery. After induction of anesthesia, arterial hypotension refractory to crystalloid therapy developed and worsened in spite of administration of a gelatin-type colloid (Gelafundina). The patient did not respond to ephedrine or dopamine and required stabilization with adrenalin in continuous perfusion for 12 hours. Later evolution was satisfactory and recovery took place without sequelae. We discuss the anesthetic implications of chronic ACEI treatment and possible hemodynamic repercussions of associated administration with gelatin-type solutions or human albumin.

Aged↗
PubMed2001

Multiple, distinct isoforms of sucrose synthase in pea.

Genes encoding three isoforms of sucrose synthase (Sus1, Sus2, and Sus3) have been cloned from pea (Pisum sativum). The genes have distinct patterns of expression in different organs of the plant, and during organ development. Studies of the isoforms expressed as recombinant proteins in Escherichia coli show that they differ in kinetic properties. Although not of great magnitude, the differences in properties are consistent with some differentiation of physiological function between the isoforms. Evidence for differentiation of function in vivo comes from the phenotypes of rug4 mutants of pea, which carry mutations in the gene encoding Sus1. One mutant line (rug4-c) lacks detectable Sus1 protein in both the soluble and membrane-associated fractions of the embryo, and Sus activity in the embryo is reduced by 95%. The starch content of the embryo is reduced by 30%, but the cellulose content is unaffected. The results imply that different isoforms of Sus may channel carbon from sucrose towards different metabolic fates within the cell.

Carbon↗
PubMed2000

The importance of stable schooling: do familiar sticklebacks stick together?

Preferences for rejoining shoals composed of familiar individuals have recently been documented in a variety of small, shallow-water fish species. Such preferences are assumed to be adaptive, since familiar groups have improved anti-predator defences and more stable dominance hierarchies. However, the design of these studies may have created conditions that elevate preferences for familiar individuals. Furthermore, in natural habitats, where significant opportunities for inter-shoal transfer may exist, it is unclear whether shoals stay together long enough for such preferences to develop. Here we present the results of a laboratory study examining whether prior familiarity influences the subsequent shoal composition of sticklebacks (Gasterosteus aculeatus) allowed to re-assort freely in a large arena tank. We show that fish from different familiarity groups associate with familiar conspecifics significantly more than predicted by a model of random assortment, suggesting that even when there is ample opportunity for inter-group transfer, shoal composition can remain stable. We discuss the phenomena that may lead to the formation of familiar groups in natural habitats. In addition, we suggest that familiarity benefits may reduce the relative value of transferring to otherwise more attractive (e.g. larger or more phenotypically matched) groups, and thereby stabilize shoal structure.

Animals↗
PubMed2000

A prospective study of a quantitative PCR ELISA assay for the diagnosis of CMV pneumonia in lung and heart-transplant recipients.

BACKGROUND: Qualitative polymerase chain reaction (PCR) for the identification of cytomegalovirus (CMV) infection has a low predictive value for the identification of CMV pneumonia. This study prospectively evaluated the application of a quantitative PCR Enzyme-Linked Immuno-Sorbent Assay (ELISA) assay in 9 lung- and 18 heart-transplant recipients who did not receive ganciclovir prophylaxis. METHODS: DNA was collected from peripheral blood polymorphonuclear leucocytes (PMNL) posttransplantation. Oligonucleotide primers for the glycoprotein B gene (149 bp) were used in a PCR ELISA assay using an internal standard for quantitation. CMV disease was defined as histological evidence of end organ damage. RESULTS: The median level CMV genome equivalents in patients with CMV disease was 2665/2 x 10(5) PMNL (range 1,200 to 61,606) compared to 100 x 10(5) PMNL (range 20 to 855) with infection but no CMV disease (p = 0.036). All patients with CMV disease had genome equivalents levels of >1200/2 x 10(5) PMNL. A cut-off level of 1,200 PMNL had a positive predictive value for CMV disease of 100% and a negative predictive value of 100%. The first detection of levels of CMV genome equivalents above a level of 1200/2 x 10(5) PMNL was at a median of 58 days (range 47 to 147) posttransplant. CONCLUSIONS: Quantitative PCR assays for the diagnosis of CMV infection may predict patients at risk of CMV disease and thereby direct preemptive treatment to high-risk patients.

Antigens, Viral↗
PubMed2000

Differences in medical students' empathy.

Medical students' Balanced Emotional Empathy Scale scores were compared by year, sex, and expressed specialty choice. Scores were lower for students choosing non-core specialties, and for M4 men students compared with M3 men students.

Analysis of Variance↗
PubMed1999

Fluoro-Gold: An alternative viability stain for multicolor flow cytometric analysis.

BACKGROUND: The viability stains propidium iodide (PI) and 7-amino-actinomycin D (7-AAD) are excited at 488 nm, as are the commonly used antibody conjugates fluorescein isothiocyanate (FITC), phycoerythrin (PE), and cyanine 5 dye covalently coupled to R-phycoerythrin (RPE-Cy5). When excited by a single laser, spectral overlap in the emission of PI and 7-AAD with RPE-Cy5 precludes the use of these viability stains for three-color immunophenotyping, particularly when evaluating low levels of marker expression in viable target cells. The ultraviolet excitable dye hydroxystilbamidine methanesulfonate (Fluoro-Gold, or FG) binds to DNA at the A-T-rich regions of the minor groove in permeabilized or dead cells. We assessed the suitability of this dye as a viability stain. METHODS: The ability of FG to detect nonviable cells in fresh and cryopreserved human apheresed peripheral blood cells was compared with that of PI and 7-AAD. The stability of FG staining and the effects of dye and cell concentration on the discrimination of nonviable cells was determined by measuring changes in the median fluorescence of viable and nonviable cells. RESULTS: FG labeling at dye concentrations of 2-8 microM is stable for at least 3 h over a wide range of cell concentrations (4 x 10(5) to 4 x 10(7) cells/ml). Costaining studies and linear regression analysis show that cell viability as determined by FG is strongly correlated with estimates using PI (r = 0.9636) and 7-AAD (r = 0.9879). CONCLUSIONS: FG is a reliable, alternative viability stain that can be used in conjunction with fluorochromes including FITC, PE, and RPE-Cy5 for multicolor analysis using dual-laser instruments.

Antigens, CD↗
PubMed1999

Reduction of lipid peroxidation with intraoperative superoxide dismutase treatment decreases intimal hyperplasia in experimental vein grafts.

BACKGROUND: Vein graft failure is commonly attributed to the development of intimal hyperplastic lesions. Oxidative stress has been implicated in the initiation and progression of atherosclerosis. In this study we examined the effects of local intraoperative treatment with polyethylene glycolated superoxide dismutase (PEG-SOD) on lipid peroxidation and on the development of intimal hyperplasia in experimental vein grafts. MATERIALS AND METHODS: Forty-one New Zealand White male rabbits had a right carotid interposition bypass graft using the ipsilateral reversed jugular vein. Sixteen animals received local PEG-SOD (4,100 units) treatment; 9 animals received the polyethylene glycol (PEG) vehicle without SOD; 16 animals were used as controls. Postoperatively, malondialdehyde (MDA, a product of lipid peroxidation) concentration and SOD activity were assessed in 3-day vein grafts by colorimetric spectrophotometry. To determine wall dimensions and vasomotor function, morphometric and isometric tension studies were performed on 28-day vein grafts. RESULTS: MDA concentration was increased 5. 7-fold (P < 0.05) in 3-day control vein grafts compared to ungrafted jugular veins. Intraoperative PEG-SOD treatment raised SOD activity 5.0-fold (P < 0.05) and reduced MDA concentration 8-fold (P < 0.05) in 3-day vein grafts compared to controls. At 28 days, intimal thickness was reduced by 35% with PEG-SOD treatment (54 +/- 4 vs 83 +/- 5; P < 0.001) compared to control vein grafts, without a change in medial thickness (77 +/- 4 vs 88 +/- 5; P = ns). The vasomotor functions of 28-day PEG-SOD-treated vein grafts to norepinephrine, serotonin, bradykinin, nitroprusside, and acetylcholine were not significantly changed when compared to controls. Treatment with PEG alone did not significantly alter lipid peroxidation, wall dimensions, or vasomotor function of vein grafts. CONCLUSION: This study demonstrates that intraoperative local treatment of vein grafts with PEG-SOD increases SOD activity and decreases lipid peroxidation for at least 3 days, resulting in reduced intimal hyperplasia at 28 days. These findings further implicate oxidative stress in the hyperplastic response of vein grafts and suggest a potential therapeutic role for PEG-SOD in the prevention of vein graft failure.

Animals↗
PubMed1999

Early morphology of accelerated vein graft atheroma in experimental vein grafts.

Vein grafts fail because of the development of intimal hyperplasia and atheroma. Recent experimental evidence suggests that the presence of hypercholesterolemia induces a three-fold increase in intimal hyperplasia with early atheroma development within 4 weeks of implantation. We have previously demonstrated endothelial cell preservation and a short-lived (3-day) polymorphonuclear leukocyte infiltrate in vein grafts. The aim of this study is to define the early morphology and ultrastructure of vein grafts implanted into a hyperlipidemic environment to provide a pathological foundation on which to examine the cellular and molecular events that determine this accelerated response. Twenty-one male New Zealand White rabbits underwent a right carotid interposition bypass graft using the ipsilateral external jugular vein; all animals received a 1% cholesterol diet for 4 weeks prior to surgery and continuing postoperatively until harvest. Animals (n = 3 per time point) were sacrificed at 60 min, 1 day, 3 days, 5 days, 7 days, 14 days, and 28 days postoperatively for scanning and transmission electron microscopy of the vein grafts. No concurrent controls were employed. The results of this study suggest that in the presence of hypercholesterolemia, the pathophysiological processes involved in the vein graft are similar to those reported for noncholesterol-fed animals. There is a sustained subendothelial response with the prolonged presence of macrophages and cellular debris and the accumulation of foam cells.

Animals↗
PubMed1999

Combination therapy of cholesterol reduction and L-arginine supplementation controls accelerated vein graft atheroma.

Hyperlipidemia contributes to the development of intimal hyperplasia and accelerated atheroma in vein bypass grafts. Dietary cholesterol reduction and oral supplementation with L-arginine have been shown to reduce accelerated atheroma in experimental vein grafts. This study extends these observations by examining the effect of the combination therapy of cholesterol reduction and L-arginine supplementation on the development of intimal hyperplasia in vein grafts in hypercholesterolemic animals. Thirty New Zealand White rabbits had a carotid vein bypass graft performed and were sacrificed at 28 days postoperatively either for morphology (light and electron microscopy) and videomorphometry, or for in vitro contractile studies. Twenty animals received a 1% cholesterol diet for 4 weeks prior to surgery. This diet was continued until harvest in ten animals. Ten cholesterol-fed animals received L-arginine supplementation (2 g/kg/day, p.o.) for 7 days preoperatively and thereafter until harvest and in addition were returned to a normal diet on the day of surgery. The last ten animals were controls (normal diet). Combined cholesterol reduction and L-arginine supplementation prevented accelerated atheroma in vein grafts, halted the change in enhanced smooth muscle cell contractility, and improved endothelial cell function. Early postoperative therapy targeting atheroma development in the high-risk patient could offer significant morphological and functional benefits.

Animals↗
PubMed1999

The development of a quantitative PCR ELISA to determine HCMV DNAaemia levels in heart, heart/lung and lung transplant recipients.

The adaptation of the polymerase chain reaction (PCR) enzyme-linked immunosorbent assay (ELISA) using a co-amplified DNA standard to quantitate the human cytomegalovirus (HCMV) glycoprotein B (gB) gene in clinical samples is described. The PCR ELISA is a solution hybridisation system with colorimetric end stage detection of amplicons. A DNA internal standard (IS) was designed by replacing a probe sequence used currently within the gB region with a heterogeneous sequence, allowing co-amplification with the same oligonucleotide primer sets and differentiation by probe hybridisation. Two DNA fragments homologous to the gB and IS sequences were generated and used for co-amplification studies to construct a standard curve. From this the copy number of the gB gene present in clinical samples could be interpolated. Co-amplification with 1000 IS copies allowed quantitation of 10-1000000 gB DNA copies in a single PCR. This assay was validated subsequently using blood samples tested by the HCMV antigenaemia assay and showed a trend of increasing HCMV DNAaemia with increasing antigenaemia levels. This rapid assay avoids using gel electrophoresis and cumbersome quantitative systems. It has the potential for early identification of patients at high risk of developing HCMV disease, and for therapeutic monitoring.

Base Sequence↗
PubMed1998

Local inhibition of tyrosine kinase activity markedly attenuates the development of intimal hyperplasia in experimental vein grafts.

BACKGROUND: Intimal hyperplasia is due to the migration and proliferation of vascular smooth muscle cells after bypass surgery. Tyrosine kinases are involved in many signal transduction pathways including cell proliferation. This study examines the effects of local treatment with the tyrosine kinase inhibitor, tyrphostin AG-51, on the formation of intimal hyperplasia in vein grafts. MATERIALS AND METHODS: Thirty-nine New Zealand White rabbits underwent interposition bypass grafting of the carotid artery using the jugular vein. In the first group (TKI), tyrphostin AG-51 (5 mg), dissolved in 600 microliter of dimethyl sulfoxide and Ringer's lactate (2:1, v:v), was used to incubate the veins ex vivo prior to grafting and delivered locally in 2.5 ml of 30% pluronic gel after grafting. The second group (DMSO) received the same treatment but without tyrphostin. In the third group (control), tyrphostin and DMSO were omitted from the incubation and gel delivery solutions. Postoperatively, vein grafts were harvested on Day 3 for Western analysis using an antiphosphotyrosine antibody (PY-20) to assess for tyrosine kinase activity, and on Day 28 for either morphologic or contractile function studies. RESULTS: Local application of the TKI to vein grafts resulted in a 49% reduction in intimal hyperplasia compared to DMSO-treated vein grafts (31 +/- 4 micrometer vs. 61 +/- 5 micrometer, P < 0.01). Treatment with DMSO alone reduced intimal hyperplasia by 28% compared to control (85 +/- 4 micrometer, P < 0.05). The contractile responses in the DMSO and TKI-treated vein grafts were equivalent. Western analysis showed a 39-fold decrease in tyrosine phosphorylation with TKI treatment compared to control. CONCLUSION: This study demonstrates that local short-term treatment with TKI produces a 49% reduction in intimal hyperplasia and suggests that phosphorylation of tyrosine residues is involved in the signaling pathways leading to the development of intimal hyperplasia in vein grafts.

Administration, Topical↗
PubMed1998

Preemptive treatment for the prevention of cytomegalovirus disease: in lung and heart transplant recipients.

BACKGROUND: Rapid quantifiable diagnostic techniques for the diagnosis of cytomegalovirus (CMV) infection may predict patients at risk of CMV pneumonitis and allow preemptive antiviral treatment. METHODS: Using CMV antigenemia as a prospective surveillance technique for CMV infection, we compared the outcome of preemptive treatment (PT) with ganciclovir, 10 mg/kg/day for 21 days directed by "high levels" of CMV antigenemia (PT group, n= 19), with the outcome in a group of historical controls (n=18) treated with ganciclovir when CMV illness occurred. Greater than 50 antigen-positive cells per 2 x 10(5) polymorphonuclear leukocytes was considered to be high-level antigenemia. RESULTS: Nine of the 18 controls developed high-level CMV antigenemia at a median of 33 days (range: 13-65 days) and 5 of the 9 developed CMV disease. Ten of the 19 PT group had high levels of CMV antigenemia detected at a median of 47 days (range: 20-63 days) and were given ganciclovir; none developed CMV disease. There was a significantly lower incidence of CMV disease in the PT group in comparison to controls (0 of 19 vs. 5 of 18: P=0.019). CONCLUSION: We have reduced the incidence of CMV disease using preemptive treatment, and because of a 100% negative predictive value, we omitted unnecessary antiviral prophylaxis for many at-risk patients.

Antibodies, Viral↗
PubMed1998

Locally applied antisense oligonucleotide to proliferating cell nuclear antigen inhibits intimal thickening in experimental vein grafts.

This study examines the effect of antisense oligonucleotide to proliferating cell nuclear antigen (PCNA) on the formation of vein graft intimal hyperplasia in vivo, using localized administration. Twenty-four New Zealand white rabbits had a right carotid interposition bypass graft using the external jugular vein and were sacrificed on the 28th postoperative day. To determine the effect of PCNA on the development of intimal hyperplasia, 6 animals had their grafts coated with a pluronic gel containing 18 base antisense oligonucleotide to PCNA (1 mg/ml), 6 received a pluronic gel containing an 18 base nonsense oligonucleotide (1 mg/ml), and 12 animals were controls (6 with and 6 without pluronic gel). These grafts were harvested for morphology and videomorphometry. There was no change in the intimal thickness between the control and gel-treated groups. (70 +/- 4 microm versus 72 +/- 4 microm; mean +/- s.e.m.; p = ns). The presence of nonsense oligonucleotide had no further effect. Antisense PCNA produced a 26% decrease in intimal thickness to 50 +/- 4 microm in the treated vein grafts (p < 0.03) without a change in medial thickness. This study shows that a local single application of antisense oligonucleotide to PCNA will reduce the intimal hyperplasia in experimental vein grafts over 28 days.

Animals↗
PubMed1998

Clinical applications of thrombolytic therapy for arterial and graft occlusion.

Catheter-directed thrombolysis and intraoperative intra-arterial thrombolysis are important adjuncts to how we care for patients with acute arterial and bypass graft occlusions. Of importance is that intra-arterial thrombolysis not to be thought of as a competitor to operative revascularization, but rather as an adjunct to what can be accomplished, which enables the responsible physician to offer the best care for these patients.

Arterial Occlusive Diseases↗
PubMed1998

Local effects of nitric oxide supplementation and suppression in the development of intimal hyperplasia in experimental vein grafts.

OBJECTIVES: The universal response of vein grafts after insertion into the arterial circulation is the development of intimal hyperplasia; smooth muscle cell proliferation and connective tissue deposition, which may be modulated in part by dysfunctional endothelial nitric oxide (NO) metabolism. This study examines the effects of single dose, local application by pluronic gel of a NO donor, S-nitroso-N-acetylpenicillamine (SNAP) and an NO synthase inhibitor nitro-L-arginine methyl ester (L-NAME) on the formation of intimal hyperplasia. MATERIALS: Forty New Zealand white rabbits underwent jugular vein interposition grafting of the common carotid artery. DESIGN: Ten animals were controls, 10 animals had the outer surface of the vein graft coated with 30% pluronic gel (2.5 ml), and 10 each were immersed for 15 min prior to insertion in Ringer lactate containing 10(-3) M of SNAP or L-NAME and then had their vein grafts coated with 2.5 ml of gel containing either SNAP (10(-3) M) or L-NAME (10(-3) M), which allows for sustained delivery for up to 6 h. On the 28th post operative day, the animals were sacrificed and vein grafts were harvested for morphology by electron microscopy (SEM and TEM) and dimensional analysis by videomorphometry. RESULTS: All vein grafts developed intimal hyperplasia. On SEM the vein grafts had a confluent layer of endothelial cells with multiple layers of smooth muscle cells representing intimal hyperplasia in TEM. There were no demonstrable morphological differences between the four groups. Local treatment with SNAP produced a significant 36% decrease in mean intimal thickness (72 +/- 4 microns vs. 45 +/- 4 microns; mean +/- S.E.M.; p < 0.01) without a change in medial thickness compared to gel-only treated groups (58 +/- 6 microns vs. 61 +/- 7 microns; p = ns). Inhibition of NO synthase by L-NAME had no effect on the development of intimal hyperplasia (72 +/- 4 microns vs. 79 +/- 10 microns; p = ns); medial thickness was also unchanged. CONCLUSION: These data confirm the protective effect of NO in vascular injury and suggest that NO synthase activity is either absent or reduced to such a level that further inhibition in this short time course is not relevant to the pathophysiology of vein graft intimal hyperplasia.

Animals↗
PubMed1998

Mutations in the gene encoding starch synthase II profoundly alter amylopectin structure in pea embryos.

Mutations at the rug5 (rugosus5) locus have been used to elucidate the role of the major soluble isoform of starch synthase II (SSII) in amylopectin synthesis in the developing pea embryo. The SSII gene maps to the rug5 locus, and the gene in one of three rug5 mutant lines has been shown to carry a base pair substitution that introduces a stop codon into the open reading frame. All three mutant alleles cause a dramatic reduction or loss of the SSII protein. The mutations have pleiotropic effects on the activities of other isoforms of starch synthase but apparently not on those of other enzymes of starch synthesis. These mutations result in abnormal starch granule morphology and amylopectin structure. Amylopectin contains fewer chains of intermediate length (B2 and B3 chains) and more very short and very long chains than does amylopectin from wild-type embryos. The results suggest that SSII may play a specific role in the synthesis of B2 and B3 chains of amylopectin. The extent to which these findings can be extrapolated to other species is discussed.

Amylopectin↗