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Biomedical subjects

A Lawrie

Publications and source records attributed to A Lawrie.

18 recordsLinked to original sources
PubMed2005

Ultrasound-mediated delivery of TIMP-3 plasmid DNA into saphenous vein leads to increased lumen size in a porcine interposition graft model.

Progressive saphenous vein graft (SVG) narrowing and occlusion remains a major limitation of coronary artery bypass grafting and is an important target for gene therapy. Ex vivo adenoviral gene transfer of tissue inhibitor of metalloproteinase 3 (TIMP-3) reduces adverse SVG remodelling postarterialization, but concerns remain over the use of viral vectors in patients. Ultrasound exposure (USE) in the presence of echocontrast microbubbles (ECM) substantially enhances nonviral gene delivery. We investigated the effects of ultrasound-enhanced gene delivery (UEGD) of TIMP-3 plasmid on vascular remodelling in porcine SVG. Maximal luciferase activity (3000-fold versus naked plasmid alone) and TIMP-3 transgene expression in porcine vascular smooth muscle cells in vitro was achieved using USE at 1 MHz, 1.8 mechanical index (MI), 6% duty cycle (DC) in the presence of 50% (v/v) BR14 ECM (Bracco). These conditions were therefore utilized for subsequent studies in vivo. Yorkshire White pigs received carotid interposition SVG that were untransfected or had undergone ex vivo UEGD of lacZ (control) or TIMP-3 plasmids. At 28 d postgrafting, lumen and total vessel area were significantly greater in the TIMP-3 group (10.1+/-1.2 and 25.5+/-2.2 mm2, respectively) compared to untransfected (6.34+/-0.5 and 20.8+/-1.9 mm2) or lacZ-transfected (6.1+/-0.7 and 19.7+/-1.2 mm2) controls (P<0.01). These data indicate that nonviral TIMP-3 plasmid delivery by USE achieves significant biological effects in a clinically relevant model of SV grafting, and is the first study to demonstrate the potential for therapeutic UEGD to prevent SVG failure.

Animals↗
PubMed2005

Control of eosinophil toxicity in the lung.

The inappropriate accumulation of eosinophils and the subsequent release of their potent pro-inflammatory mediator arsenal are thought to be important contributors to the pathogenesis of asthma and other allergic diseases. It is also becoming apparent that eosinophils may play a role in the orchestration of immune responses in the asthmatic lung. There is therefore much interest in the development of strategies to limit or prevent eosinophil-induced toxicity. The mechanisms by which eosinophils accumulate in the peribronchial tissues of the lung are complex and include enhanced differentiation and release from the bone marrow, selective adhesion and transendothelial migration, directed movement in response to specific chemotactic mediators and finally prolonged survival as a consequence of delayed apoptosis. Thus it can be appreciated that there are many points at which the toxicity of eosinophils can be limited or even prevented. Important areas for potential advances in glucocorticoid (GC) development include efforts to dissociate their anti-inflammatory effects from unwanted side effects. Other areas include the development of humanized monoclonal antibodies against IL-4, IL-13 and IL-5 together with the inhibition of adhesion pathways and/or chemokines responsible for eosinophil accumulation in the asthmatic lung. Several avenues of research are currently underway in an attempt to define mechanisms by which pro-inflammatory cells such as eosinophils can be safely removed from the asthmatic lung through apoptosis induction and their subsequent ingestion by phagocytes. This review will discuss both the potential and shortcomings of these diverse approaches to limit eosinophil toxicity in the asthmatic lung.

Animals↗
PubMed2003

Eosinophils from patients with asthma express higher levels of the pan-leucocyte receptor CD45 and the isoform CD45RO.

BACKGROUND: Eosinophils and their secreted mediators are heavily implicated as effector cells in asthma and other allergic diseases. Comparisons were made between expression of CD45, CD45RA, CD45RB and CD45RO by eosinophils from asthmatic patients and non-asthmatic atopic and non-atopic, non-asthmatic control subjects. METHODS: Twenty-seven patients with asthma and 33 control subjects were recruited for the study. Eosinophil expression of CD45, CD45RA, CD45RB and CD45RO was established by immunostaining and flow cytometry was performed on whole leucocyte samples. Eosinophil apoptosis in response to CD45 and CD45 isoform monoclonal antibody (mAb)-dependent receptor ligation was assessed by binding of annexin V and flow cytometry. RESULTS: Eosinophils from patients with asthma expressed significantly (P<0.05) higher levels of pan-CD45 and CD45RO compared with eosinophils from non-asthmatic, non-atopic subjects. No significant correlations were found between expression of either pan-CD45 or CD45RO and the degree of symptoms in the asthmatic patients as defined by lung function (FEV1 and FEF25-75) and methacholine PD20. Increased expression of pan-CD45 or CD45RO did not appear to be a consequence of the atopic phenotype. Higher expression of pan-CD45 or CD45RO by eosinophils from asthmatic patients was not associated with greater sensitivity to CD45 and CD45RO mAb receptor ligation-induced eosinophil apoptosis. CONCLUSION: Higher expression of CD45 and CD45RO by eosinophils from asthmatic patients appeared to be a consequence of asthma rather than atopy and further supports a role for activated eosinophils in asthma.

Adolescent↗
PubMed2003

Reduced eosinophil apoptosis in induced sputum correlates with asthma severity.

This study was carried out to investigate the relationship between induced sputum eosinophil apoptosis and clinical severity score, airway obstruction and symptom scores in patients with chronic stable asthma. Altogether, 41 chronic stable asthmatic subjects of varying severity defined by Aas score and 17 control subjects underwent spirometry, symptom questionnaire and successful sputum induction. Sputum was processed and cytospins prepared for light microscopy to determine normal and apoptotic eosinophils. Mild asthmatic subjects had a significantly lower percentage sputum eosinophils and a significantly higher eosinophil apoptotic ratio (AR) than moderate or chronic severe asthmatics. Severe asthmatic subjects had a significantly greater age, duration of asthma and sputum eosinophil count x mL(-1) than mild asthmatic subjects. Asthmatic subjects' symptom scores, severity scores and age inversely correlated with AR and the percentage of sputum eosinophils. Baseline forced expiratory volume in one second inversely correlated with percentage sputum eosinophils and positively correlated with AR. The study demonstrates a relationship between reduced sputum eosinophil apoptosis and increased clinical severity of chronic stable asthma, providing additional evidence that eosinophil apoptosis may be important in the resolution of eosinophilic airway inflammation in asthma.

Adult↗
PubMed2001

Ultrasound gene therapy: on the road from concept to reality.

The promise of gene therapy lies in the potential to ameliorate or cure conditions that are resistant to conventional therapeutic approaches. Progress in vascular and all other fields of gene therapy has been hampered by concerns over the safety and practicality of recombinant viral vectors and the inefficiency of current nonviral transfection techniques. This review summarizes the increasing evidence that exposure of eukaryotic cells to relatively modest intensity ultrasound, within the range emitted by diagnostic transducers, either alone or in combination with other nonviral techniques, can enhance transgene expression by up to several orders of magnitude over naked DNA alone. In combination with the flexibility and excellent clinical safety profile of therapeutic and diagnostic ultrasound, these data suggest that ultrasound-assisted gene delivery has great promise as a novel approach to improve the efficiency of many forms of nonviral gene delivery.

Genetic Therapy↗
PubMed2000

Microbubble-enhanced ultrasound for vascular gene delivery.

Progress in cardiovascular gene therapy has been hampered by concerns over the safety and practicality of viral vectors and the inefficiency of current nonviral transfection techniques. We have previously reported that ultrasound exposure (USE) enhances transgene expression in vascular cells by up to 10-fold after naked DNA transfection, and enhances lipofection by up to three-fold. We report here that performing USE in the presence of microbubble echocontrast agents enhances acoustic cavitation and is associated with approximately 300-fold increments in transgene expression after naked DNA transfections. This approach also enhances by four-fold the efficiency of polyplex transfection, yielding transgene expression levels approximately 3000-fold higher than after naked DNA alone. These data indicate an important role for acoustic cavitation in the effects of USE. Ultrasound can be focused upon almost any organ and hence this approach holds promise as a means to deliver targeted gene therapy in cardiovascular conditions such as such angioplasty restenosis and in many other clinical situations.

Albumins↗
PubMed1999

Ultrasound enhances reporter gene expression after transfection of vascular cells in vitro.

BACKGROUND: Restenosis after percutaneous coronary intervention remains a serious clinical problem. Progress in local gene therapy to prevent restenosis has been hindered by concerns over the safety and efficacy of viral vectors and the limited efficiency of nonviral techniques. This study investigates the use of adjunctive ultrasound to enhance nonviral gene delivery. METHODS AND RESULTS: Cultured porcine vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) were transfected with naked or liposome-complexed luciferase reporter plasmid for 3 hours. Ultrasound exposure (USE) for 60 seconds at 1 MHz, 0.4 W/cm2, 30 minutes into this transfection period enhanced luciferase activity 48 hours later by 7.5-fold and 2. 4-fold, respectively. Luciferase activity after lipofection of ECs was similarly enhanced 3.3-fold by adjunctive USE. USE had no effect on cell viability, although it inhibited VSMC but not EC proliferation. CONCLUSIONS: Adjunctive USE was associated with enhanced transgene expression in VSMCs and ECs and reduced VSMC but not EC proliferation in vitro, which suggests that ultrasound-assisted local gene therapy has potential as an antirestenotic therapy.

Animals↗
PubMed1999

Indirubin, the active constituent of a Chinese antileukaemia medicine, inhibits cyclin-dependent kinases.

Indirubin is the active ingredient of Danggui Longhui Wan, a mixture of plants that is used in traditional Chinese medicine to treat chronic diseases. Here we identify indirubin and its analogues as potent inhibitors of cyclin-dependent kinases (CDKs). The crystal structure of CDK2 in complex with indirubin derivatives shows that indirubin interacts with the kinase's ATP-binding site through van der Waals interactions and three hydrogen bonds. Indirubin-3'-monoxime inhibits the proliferation of a large range of cells, mainly through arresting the cells in the G2/M phase of the cell cycle. These results have implications for therapeutic optimization of indigoids.

Animals↗
PubMed1997

Risk factors and medical follow-up of drug users tested for hepatitis C--can the risk of transmission be reduced?

Of 1728 patients attending a regional drug and alcohol clinic, 202 were considered at risk of hepatitis C virus (HCV). Forty-nine per cent (99/202) agreed to testing-67% (67) were HCV antibody positive. Age and a history of needle sharing was the significant factor associated with positive HCV status. Patients on methadone maintenance medication were more-likely to have been HCV positive, but significantly (p = 0.005) less likely to have shared needles in the previous year. Seventy-three per cent (49/67) attended for follow-up at a "liver clinic". Fifty per cent were infected with genotype 1a. Eighteen patients were biopsied and all were abnormal, ranging from mild hepatitis to severe fibrotic hepatitis. Attendance for medical follow-up was poor, which emphasizes the importance of preventative measures such as methadone maintenance programmes for reducing the spread of HCV.

Journal Article↗
PubMed1996

A randomised comparison of oral and vaginal misoprostol for cervical priming before suction termination of pregnancy.

OBJECTIVE: To assess the effectiveness and acceptability of oral misoprostol, self-administered 12 h before surgery, as a cervical priming agent prior to day case suction termination of pregnancy. DESIGN: Randomised trial comparing oral misoprostol with the local standard regimen of vaginal misoprostol. SUBJECTS: Sixty consecutive women scheduled for day case suction termination in one gynaecology unit. INTERVENTIONS: Cervical priming with misoprostol 400 mg orally, 12 h prior to surgery or 800 mg vaginally, two to four hours prior to surgery. MAIN OUTCOME MEASURES: Basal cervical dilatation, cumulative force required to dilate the cervix to 9 mm, operative blood loss and side effects (nausea, vomiting, diarrhoea, abdominal pain and vaginal bleeding). RESULTS: There were no significant differences between the oral and vaginal treatment groups in relation to basal dilatation, cumulative force to achieve 9 mm dilatation or gastrointestinal side effects. However, those in the oral group experienced more severe pain and heavier pre-operative bleeding. Two patients in the oral group experienced incomplete abortion at home after taking misoprostol and a further patient required early admission because of heavy bleeding. CONCLUSIONS: Because of the unpredictability of action of oral misoprostol, with incomplete abortion or heavy bleeding occurring prior to admission in three patients, we cannot recommend the dosage schedule evaluated here for routine clinical use.

Abortifacient Agents, Nonsteroidal↗
PubMed1993

Quantitative and qualitative assessment of plasma von Willebrand factor in classic Kaposi's sarcoma.

BACKGROUND: von Willebrand factor (vWF) is synthesized almost exclusively by endothelial cells and is stored there as ultra-high-molecular-weight multimers. The vWF multimers that are detected in the plasma are smaller than those stored within the endothelium. In two previous studies, comprising small series of cases with classic Kaposi's sarcoma (KS), an endothelium-derived tumor, increased levels of plasma von Willebrand factor antigen (VWF:Ag, the antigenic structure) were reported, suggesting that vWF:Ag may be a marker of endothelium proliferation. OBJECTIVE: Our purpose was to investigate the quantitative as well as qualitative alterations of plasma vWF in a large series of patients with classic KS at various stages of the disease. METHODS: Levels of plasma vWF:Ag were studied in 38 patients with classic KS confined to the skin at various stages of the disease and compared with a control group. Thirty-three patients had active KS (i.e., with skin lesions) and five were in remission. In five patients with active KS multimeric analysis of plasma vWF was also performed. RESULTS: The levels of vWF:Ag were significantly higher among KS patients than in the control group (n = 29, p < 0.01). Levels of vWF:Ag were also significantly higher in patients with active disease as compared with those in remission (p < 0.05). No correlation was found between vWF:Ag levels and the extent of KS. Analysis of the multimeric pattern of plasma vWF showed enhanced staining of all bands, particularly the intermediate and high molecular weight forms, which resemble the endothelial forms as opposed to normal circulating vWF multimers. CONCLUSION: Quantitative as well as qualitative alterations in plasma vWF were found in patients with KS, which may reflect the destruction or activation of endothelial cells within the lesions. vWF:Ag may serve as a marker of disease activity in classic KS; however, it is not a good marker for the extent of the disease.

Aged↗
PubMed1993

Porcine platelets contain an increased quantity of ultra-high molecular weight von Willebrand factor and numerous alpha-granular tubular structures.

Immunoelectronmicroscopy of human platelet alpha-granules reveals that von Willebrand factor (vWf:Ag) colocalizes with a small number of discrete tubular structures which appear identical to those observed within the Weibel-Palade bodies of endothelial cells. Although it is likely that tubules are composed of vWf:Ag as they are absent in severe vWD porcine platelets, their exact structural and functional nature is still unclear. In this study quantitative/qualitative analysis of vWf:Ag was undertaken in a series of platelet preparations obtained from normal pigs, normal humans and various vWD patients. Electron microscopy confirmed that normal pig platelet alpha-granules contain numerous, regularly spaced tubular structures eccentrically located and coincident with immunogold staining of vWf:Ag. In contrast, normal human platelet alpha-granules contain significantly fewer tubules (usually four to six) which are absent or reduced in number within various vWD platelet sections. Furthermore, the pig platelet lysates not only contained a full complement of multimers but also demonstrated significant intense staining of ultra-high MW material, irrespective of the presence or absence of proteolytic inhibitors. This ultra-high MW vWf appears similar to that observed within lysates prepared from endothelial cells and is susceptible to degradation to lower MW multimers. This study suggests that the tubular structures within alpha-granules and Weibel-Palade bodies may be composed of, or structurally related to, the ultra-high MW intracellular form of vWf:Ag.

Animals↗
PubMed1992

Unique expression of von Willebrand factor by type IIA von Willebrand's disease endothelial cells.

Endothelial cells (EC) were cultured from the umbilical cord of a male neonate whose mother was previously diagnosed with type IIA von Willebrand's disease (vWd). The diagnosis of type IIA vWd in the proband was confirmed by low ristocetin activity and the absence of the highest molecular weight (MW) forms of von Willebrand factor (vWf) in his platelet poor plasma. The vWf of EC cultured from the neonate's umbilical cord differed from that of control EC and the cell line EA.hy926 in two respects. Firstly, the full range of molecular weight forms was present in the patient EC lysate and, secondly, vWf:Ag expression was approximately seven-fold greater than that of control cells. Platelet lysates prepared from other affected members of the type IIA vWd family in the presence or absence of proteolytic inhibitors demonstrated a near normal vWf multimeric distribution. Resistance of these high MW forms to heat degradation was conferred by the presence of proteolytic inhibitors. Moreover, the full plasma vWf multimeric distribution could not be restored by the inclusion of EDTA. N-ethylmaleimide and leupeptin in the anticoagulant during the rapid preparation of platelet poor plasma. These findings lend support to the heterogeneous nature of type IIA vWd and has possible implications in the understanding of the intracellular processes involved in the biosynthesis and storage of the vWf macromolecular complex as well as the pathogenesis of type IIA vWd.

Blood Platelets↗
PubMed1990

The rabies viruses of bats.

In the 1930s rabies was shown to affect blood-, insect- and fruit-eating bats. We have prepared anti-nucleocapsid monoclonal antibodies (MAbs) using Mokola and bat (Lagos, Duvenhage and Denmark) rabies viruses as immunogens. With these MAbs we have examined rabies viruses from vampire, insectivorous and frugivorous bats from the Americas, Africa, Europe and the Soviet Union and have compared them with isolates from terrestrial species including man. As well as confirming the findings of others with viruses of African and American bat origin, the results revealed the presence of a second biotype in European bats and demonstrated the presence of serotype 1 as well as serotype 4 viruses in bats of the Soviet Union.

Africa↗
PubMed1989

Primary thrombocythaemia: diagnostic criteria and a simple scoring system for positive diagnosis.

Forty new patients with elevated platelet counts (greater than 600 x 10(9)/l) and without palpable splenomegaly were assigned to diagnostic groups defined by essentially conventional criteria after 3 months follow up: Proliferative (17), reactive (17) or unclassified (six). Mean platelet volume (MPV), platelet distribution width (PDW), platelet nucleotide ratio (ATP:ADP), unstimulated BFU-E derived colony formation from peripheral blood, spleen scan and clinical ischaemia were assessed at the outset, with a view to defining diagnostic criteria for distinguishing primary thrombocythaemia from reactive thrombocytosis. All except the first variable were significantly associated with diagnostic group (P less than 0.05). A simple scoring system was devised: enlarged spleen on scan, or presence of BFU-E, each scored 2; elevated PDW (greater than 2 SD from mean), elevated ATP:ADP (greater than 4 SD from mean) or presence of clinical ischaemia, each scored 1. Score totals greater than or equal to 3 predicted primary thrombocythaemia, and totals less than 3 suggested reactive thrombocytosis (predictive value 89%). The system correctly predicted diagnosis in four out of four (probably six out of six) patients whose diagnosis was not apparent initially, and thus whose results were not used in constructing the scoring system. Exclusion of BFU-E from the system resulted in only one incorrect prediction in this group.

Blood Platelets↗