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Biomedical subjects

C Burrell

Publications and source records attributed to C Burrell.

10 recordsLinked to original sources
PubMed2006

Aortic root replacement in cardiac dextroversion.

Adult cardiac surgery in patients with malrotation of the heart is rare. A 60 year-old lady, with known cardiac dextroversion, presented with dyspnoea and pre-syncopal attacks. Echocardiographical and radiological investigation confirmed the dextroversion, with clockwise rotation of the heart through its longitudinal axis. This resulted in the right ventricular outflow tract and pulmonary artery being wrapped anteriorly around the aorta, with posterior displacement of the right atrium. The presence of a heavily calcified, bicuspid aortic valve and dilated ascending aorta was also demonstrated. At surgery, venous cannulation was established by rotating the heart anticlockwise and access to the aortic valve gained with a more superior oblique aortotomy. In the presence of a dilated ascending aorta with a calcified, bicuspid aortic valve, the aortic root was replaced with a valved conduit. To the authors' knowledge, this is the first report of an aortic root replacement in a patient with cardiac dextroversion.

Aorta, Thoracic↗
PubMed2005

Are humans infected by Hantaviruses in Australia?

Hantavirus antibody-positive rodents have been found across Australia although, to date, there are no reports of infections in humans. This could be due to misdiagnosis clinically and/or inadequate laboratory technique/skills. There are close trading ties between Australia and Asian countries as well as our geographical neighbours where both human and rodent infections are found, so importation is a continuing threat. We consider that further sero-epidemiological surveys are warranted among rodents (especially those captured from ports in Australia), in patients from renal and respiratory wards of hospitals, and in residents and employees close to harbours using more specific and sensitive laboratory techniques than have been available in the past.

Australia↗
PubMed1999

Ultrasound guided percutaneous thrombin injection for the treatment of iatrogenic pseudoaneurysms.

Iatrogenic aneurysms are usually postcatheterisation pseudoaneurysms of the femoral artery. Until recently, the treatment of choice was ultrasound guided compression repair. A case of pseudoaneurysm of the axillary artery, arising as a complication of pacemaker insertion in an 83 year old man is reported. Compression repair was not possible in this case, and so the aneurysm was occluded by percutaneous ultrasound guided thrombin injection directly into the aneurysm sac. Percutaneous ultrasound guided thrombin injection is a promising new minimally invasive technique for the treatment of iatrogenic pseudoaneurysms.

Aged↗
PubMed1998

De novo reverse transcription of HTLV-1 following cell-to-cell transmission of infection.

Analogous to transmission of human T-cell leukemia virus type 1 (HTLV-1) in vivo, an in vitro cell-to-cell infection model was established by coculturing MT-2 cells as virus donors and HUT78 cells as recipients. At a donor:recipient ratio of 1:2, cell fusion occurred and a new round of HTLV-1 genome replication was initiated in the cocultured cells. Newly synthesized unintegrated viral DNA was detected by Southern blot within 4-8 h and then increased between 8 and 48 h following cell mixing. The most dominant species of unintegrated viral DNA was 3.7 kb in size which hybridized to a full-length HTLV-1 DNA probe but not to a Kpnl viral DNA fragment that is absent from a defective proviral genome that has been previously identified in MT-2 cells. Northern blot analysis showed large amounts of viral RNA in the virus donor cells and in the cocultured cells, with a 3.4-kb species being the most abundant. This 3.4-kb RNA gave a pattern identical to that of the 3.7-kb unintegrated viral DNA in hybridization studies using the two probes. It seems likely that the unspliced RNA transcript from the defective proviral genome in MT-2 cells was effectively reverse transcribed upon initiation of cell-to-cell viral transmission to susceptible HUT78 cells. Despite active de novo reverse transcription, however, viral RNA levels remained unchanged following cell-to-cell transmission of HTLV-1 infection and no viral antigen production could be attributed to the newly initiated round of viral genome replication. As an abortive infection model this simple cell-to-cell infection system warrants more detailed study as it has the potential to provide reliable information regarding the early events in HTLV-1 transmission and infection.

Cell Line↗
PubMed1997

Increased recruitment of hematopoietic progenitor cells underlies the ex vivo expansion potential of FLT3 ligand.

The ligand for flt-3 (FLT3L) exhibits striking structural homology with stem cell factor (SCF) and monocyte colony-stimulating factor (M-CSF) and also acts in synergy with a range of other hematopoietic growth factors (HGF). In this study, we show that FLT3L responsive hematopoietic progenitor cells (HPC) are CD34+CD38-, rhodamine 123dull, and hydroperoxycyclophosphamide (4-HC) resistant. To investigate the basis for the capacity of FLT3L to augment the de novo generation of myeloid progenitors from CD34+CD38- cells, single bone marrow CD34+CD38- cells were sorted into Terasaki wells containing serum-free medium supplemented with interleukin-3 (IL-3), IL-6, granulocyte colony-stimulating factor (G-CSF), SCF (4 HGF) +/- FLT3L. Under these conditions, FLT3L recruited approximately twofold more CD34+CD38- cells into division than 4 HGF alone. The enhanced proliferative response to FLT3L was evident by day 3 and was maintained at all subsequent time points examined. In accord with these findings, we also show that transduction of CD34+CD38- cells with the LAPSN retrovirus is enhanced by FLT3L. The results of these experiments therefore indicate that increased recruitment of primitive HPC into cell cycle underlies the ex vivo expansion potential of FLT3L and also its ability to improve retroviral transduction of HPC.

ADP-ribosyl Cyclase↗
PubMed1996

Long-term protection against HIV-1 infection conferred by tat or rev antisense RNA was affected by the design of the retroviral vector.

We have constructed a series of retroviral vectors in which the expression of antisense RNA targeted at the full length coding sequence of HIV-1 tat or rev was driven by three different promoters and in the context of double-copy or single-copy vectors. Jurkat cells transduced by these vectors were shown to express the expected tat or rev antisense RNA without alteration in cell proliferation or surface CD4 expression. After challenge with HIV, four patterns of protection were identified, with the degree of protection being determined primarily by the design of the expression system. In those patterns showing long-term complete protection, we could detect no HIV p24 in the culture supernatants or in the cells, and no HIV RNA or HIV proviral DNA (by PCR), during a 23-week follow-up. Experiments designed to rescue any live virus still formed in the culture after 20 weeks' challenge demonstrated that, with some constructs, infectious virus could no longer be isolated, while with other constructs, only a low level of infectious virus was still being formed and providing a continuing virus challenge, although all other markers of infection remained undetectable. Our results demonstrated that antisense RNA expression driven by tRNA promoter in the context of a double-copy vector conferred better long-term protection against HIV infection compared to that driven by HIV LTR or MLV LTR promoters, and that the optimized vectors may be useful in developing a gene therapy against HIV-1 infection and AIDS.

Base Sequence↗
PubMed1993

Characterization of HIV replication complexes early after cell-to-cell infection.

In this study, we have characterized the HIV DNA-containing replication complexes present in cells early after cell-to-cell infection, using sucrose gradient sedimentation and immunoprecipitation. Six hours after cell-to-cell infection, a cytoplasmic HIV replication complex sedimented as a large structure (320S). This replication complex was precipitated by antisera to three virus-coded enzymes (reverse transcriptase, integrase, protease), to the matrix protein (p17), and to cellular histones but not to the major capsid protein (p24). This replication complex was not associated with cell membranes and could not be dissociated into smaller discrete subunits, using detergents. Nuclear extracts from the same cell-to-cell infection contained a smaller (80S) complex that lacked reverse transcriptase and matrix protein (p17). Cytoplasmic replication complexes from a cell-free virus infection sedimented as 160S structures under identical conditions, as previously reported. Our results indicate that, following cell-to-cell transmission of HIV, all the HIV pol gene products, the matrix protein p17, and cellular histones are present in cytoplasmic replication complexes that are taking part in or have completed reverse transcription. Transportation of the cytoplasmic replication complex to the nucleus is associated with structural changes, including a reduction in size and altered protein composition.

Base Sequence↗
PubMed1993

Cell-to-cell transmission of human immunodeficiency virus infection induces two distinct phases of viral RNA expression under separate regulatory control.

A cell clone persistently infected with human T cell-lymphotrophic virus type IIIB (H3B cells) contained mainly the multiply spliced (2 kb) and singly spliced (4.3 kb) species of human immunodeficiency virus (HIV) RNA. When H3B cells were co-cultured with susceptible HUT78 cells, cell fusion occurred within 4 h of cell mixing and was accompanied by a marked increase of the unspliced full-length (9.2 kb) HIV RNA. This first phase of viral RNA induction (4 to 12 h post-infection) was followed by a second phase of viral RNA synthesis from 24 h p.i. in which there were significant increases in all three species of HIV RNA. Reverse transcriptase (RT) inhibitors such as azidothymidine (AZT) at concentrations that abolished de novo HIV DNA synthesis, abolished the first phase but not the second phase of viral RNA synthesis in our model system. A comparable one-step cell-free virus infection showed a pattern of viral RNA synthesis similar to that of the cell-to-cell transmission of infection. However, viral RNA synthesis following cell-free virus infection was totally inhibited by RT inhibitors. The early phase (4 to 12 h) expression of 9.2 kb HIV RNA is likely to use newly synthesized HIV DNA as template; during this phase, HIV RNA and DNA syntheses occur simultaneously, with each process being dependent on the other for maximal yield. During the later (24 to 48 h) phase, all three HIV RNA species may be transcribed at least in part from proviral DNA from the original donor cells. This later phase may provide one of the mechanisms for natural spread of virus to new cells and for enhanced viral gene expression in vivo, despite the presence of AZT.

Cell Line↗
PubMed1991

Bloody needles: the volumes of blood transferred in simulations of needlestick injuries and shared use of syringes for injection of intravenous drugs.

Residual HIV-infected blood in needles and syringes is a source of HIV infection. Using radiolabelled blood we have stimulated needlestick injuries and sharing of syringes by intravenous drug users and quantified the volumes of blood which could be transferred to recipients in these situations. Up to 0.75 microliters of blood was transferred in needlestick simulations, but there was a large variation. In simulations of needlesharing, seven to ten times more blood was transferred from the index user to the first sharer when 2 ml syringes were used compared with 1 ml syringes. Washing with water was not effective in removing 'infected' blood from a syringe.

HIV Infections↗