Biomedical subjects

B Cameron

Publications and source records attributed to B Cameron.

At least 19 recordsLinked to original sources

PubMed2005

The effectiveness of treating juvenile dermatomyositis with methotrexate and aggressively tapered corticosteroids.

OBJECTIVE: Childhood dermatomyositis (DM) is often a chronic disease, lasting many years. It has traditionally been treated with long-term corticosteroid therapy; side effects are often seen. For more than a decade, methotrexate (MTX) has been safely used for the treatment of juvenile arthritis. Here, we report use of MTX as first-line therapy for DM, along with aggressively tapered corticosteroids, in an attempt to reduce treatment-related side effects. METHODS: We studied an inception cohort of 31 children with DM who were rigorously followed up in our myositis clinic, and compared them with a control group of 22 patients with incident cases of juvenile DM who received treatment just before we instituted a policy of first-line therapy with MTX. The mean starting dosage of MTX in the study group was 15 mg/m(2)/week. RESULTS: Both groups had similar improvement in strength and physical function; however, the median time during which patients in the study group received corticosteroids was 10 months, compared with 27 months for controls (P < 0.0001). As a result, the cumulative prednisone dose in the study group was approximately half that in the control group (7,574 mg versus 15,152 mg; P = 0.0006). The study group had greater height velocity during the first year of treatment and a smaller increase in the body mass index over the first 2 years. In the control group, the relative risk of cataracts developing was 1.95 (95% confidence interval 1.05-4.17). Side effects of MTX were rarely observed. CONCLUSION: Use of MTX in conjunction with an aggressively tapered course of prednisone may be as effective as traditional long-term corticosteroid therapy for children with DM, while decreasing the cumulative dose of corticosteroids.

Dermatomyositis↗

PubMed2004

Improvement of pCOR plasmid copy number for pharmaceutical applications.

Production of pharmaceutical-grade plasmid DNA is becoming important as the demand for clinical batches is steadily growing. pCOR plasmids have been specifically designed and used for gene delivery into humans, and have been produced by high cell-density fermentation with a yield of 100 mg/l. This yield could probably be increased as long as the release specifications of bulk plasmid remain the same, particularly in terms of plasmid sequence. We report here the use of genetic approaches in Escherichia coli to increase the copy number of pCOR. The bacterial gene encoding the pi initiator-protein, which plays a pivotal role in pCOR replication, was mutagenized. A fluorescence-based screening methodology in E. coli was used to identify novel copy-up mutations. A particular combination of copy-up mutations translated into a 3-5-fold increase in monomer pCOR plasmid DNA per biomass unit.

DNA Helicases↗

PubMed2004

Production of pro-inflammatory cytokines correlates with the symptoms of acute sickness behaviour in humans.

BACKGROUND: Elaboration of the concept of cytokine-induced sickness behaviour in recent years has opened new avenues for understanding brain involvement in sickness and recovery processes. Additionally, this has led to much speculation about the role of the immune system in neuropsychiatric syndromes, including depression and chronic fatigue. However, few studies have examined this phenomenon as it naturally occurs in sick humans, and none has attempted to document the quantitative relationships between cytokine levels and non-specific symptoms. The aim of this research was to examine human sickness behaviour and its immunological correlates in documented Epstein-Barr virus (EBV), Q fever or Ross River virus (RRV) infections. METHOD: We studied two separate samples. The first consisted of 21 patients with acute Q fever. The second included 48 patients with acute RRV or EBV infection. Psychological and somatic symptom profiles were derived from self-report measures completed at enrolment. Quantification of proinflammatory cytokines [interleukin (IL)-1beta and IL-6] in sera and supernatants of peripheral blood mononuclear cell (PBMC) cultures was undertaken by specific ELISAs. RESULTS: Levels of IL-1beta and IL-6 spontaneously released from PBMC cultures were consistently correlated with reported manifestations of acute sickness behaviour including fever, malaise, pain, fatigue, mood and poor concentration. CONCLUSIONS: IL-1beta and IL-6 produced as part of the host response represent sensitive markers of sickness behaviour in humans with acute infection. Further work is needed to systematically characterize the spectrum and natural history of sickness behaviour in humans and to elucidate its biological basis.

Acute Disease↗

PubMed2002

Mechanistic studies on AMD6221: a ruthenium-based nitric oxide scavenger.

Nitric oxide is a mediator of many disease states. Previous studies have demonstrated that ruthenium(III) polyaminocarboxylates can react with NO to form stable complexes reducing the levels of nitrite in the culture medium of stimulated RAW264 macrophages and reverse the NO-mediated hypotension in animal models of septic shock. It was necessary to confirm that these observations were due to NO scavenging and not inhibition of the NO metabolic pathway. Using RAW264 cells it was confirmed that [Ru(H(3)dtpa)(Cl)] (AMD6221) was neither acting at the level of iNOS induction, nor as an inhibitor of iNOS by measuring iNOS mRNA by RT-PCR and protein by Western blot and enzyme activity. Using HPLC, the nitrosyl adduct of reaction of AMD6221, [Ru(H(2)dtpa)NO], was identified in the medium of stimulated RAW264 cells co-incubated with AMD6221, concomitant with a stoichiometric reduction in nitrite/nitrate levels, thus confirming that the ruthenium(III) polyaminocarboxylates exert their pharmacological effect by scavenging NO.

Animals↗

PubMed2001

Stabilization of recombinant adenovirus: site-directed mutagenesis of key asparagine residues in the hexon protein.

The quality and stability of recombinant adenovirus preparations for gene therapy trials are currently analyzed by anion-exchange HPLC. It was shown that the retention time of the adenovirus peak increased over the course of time upon storage in current liquid formulations. The number of isoaspartate residues at the outer surface of the particles also increased in parallel in these preparations. A recombinant adenovirus AV3760 was constructed with a modified hexon protein in which all four accessible Asn residues engaged in Asn-Gly pairs were changed into Leu (Asn244, Asn255, Asn437) or Ala (Asn276). The retention time of AV3760, as measured by HPLC, was unchanged after 2 months at +20 degrees C as opposed to the control adenovirus. This demonstrates that the shift in retention time is caused by an increase in carboxyl groups on the outer surface of the virion due to deamidation of the above Asn residues. The modifications introduced in the hexon protein reduced the rate of Asn deamidation, without adverse effects on the infectivity of the virions. By reducing microheterogeneity in recombinant adenovirus, this work represents a significant advance in the development of a stable pharmaceutical vector for gene therapy.

Adenoviridae↗

PubMed2001

Regionalisation of rural medical training in far north Queensland: a learning experience for medical educators and managers.

The need for an appropriate, dedicated vertically-integrated training pathway for rural doctors, provided by regional consortia of educational organisations, has been clearly identified by Rural Doctors Association of Queensland (RDAQ) and The Australian College of Rural and Remote Medicine (ACRRM) as a key strategy to resolve rural medical workforce issues. The opportunity to put the ideas into action is now here with rural doctors responding to the challenge of managing more reform in general practice all over Australia. In Far North Queensland, the ongoing reform of general practice education has been challenging, with many lessons learned by both educators and managers. This paper describes the management of change, and outlines key principles and characteristics of a successful regional rural medical training system, building on the lessons learned from the Rural and Remote Area Placement Program (RRAP) and other projects.

Cooperative Behavior↗

PubMed2001

Factors affecting the outcome of total shoulder arthroplasty.

Total shoulder arthroplasty (TSA) has become the treatment of choice for most glenohumeral arthritides. Results are variable and depend on many factors, including normal and prosthetic anatomy and biomechanics, surgical technique, rotator-cuff integrity, bone deficiency, and postoperative rehabilitation. In this article, we discuss these factors and their influence on achieving successful TSAs.

Arthroplasty, Replacement↗

PubMed2001

Outcomes in rural obstetrics, Atherton Hospital 1991-2000.

Analysis of annual obstetric audit data collected over the decade 1991-2000 from the Atherton Hospital in Far North Queensland provides ongoing evidence of safe obstetric practice provided by a group of non-specialist doctors in a rural community. During that period, there were 2997 deliveries; of these, 2400 (80.1%) were public patients and 596 (19.9%) were private patients. There were 16 perinatal deaths (perinatal mortality rate 5.3/1000). This is remarkably consistent with the outcome of the previous decade, 1981-90, when the total deliveries was 2883 with 15 perinatal deaths (perinatal mortality rate 5.2/1000). However, compared with 1981-90, the number of Caesarean sections rose from an overall rate of 13.0% (public 10.6%; private 18.3%) to an overall rate of 17.4% (public 16.7%; private 20.4%). In 1981-90, there were 909 private confinements (31.5% of total) and in 1991-2000 there were 597 (19.9% of total). This decline in the number of private obstetric cases may have significant implications for future models of care. There were no maternal deaths in the 20 years 1981-2000.

Delivery, Obstetric↗

PubMed2000

An improved anion-exchange HPLC method for the detection and purification of adenoviral particles.

We have developed an anion-exchange high-performance liquid chromatography (HPLC) method using Q Sepharose XL (Amersham Pharmacia Biotech) as adsorbent to analyze samples containing adenovirus. This method has several major advantages over the HPLC method previously described for quantitating particles, namely (1) a >10-fold improvement in the detection limit of adenovirus in crude preparations; (2) absence of interferences originating from nucleic acids and proteins which usually contaminate crude samples; (3) unprecedented sharpness and symmetry of adenovirus peak, rendering the identification of the viral peak unambiguous, even in extremely crude and dilute preparations; and (4) no enzymatic treatment required even for crude samples. This assay was used to quantitate particles in samples taken at the transfection and amplification stages of production of various recombinant adenovirus, and in cultures of wild-type adenovirus of different serotypes. A modification of this analytical method was also developed for the purification of infectious adenovirus particles, including fiber-modified and third-generation recombinant viruses, giving highly purified preparations from low-titer crude lysates with an excellent overall recovery (50-74%).

Adenoviridae↗

PubMed1999

Plasmid DNA size does not affect the physicochemical properties of lipoplexes but modulates gene transfer efficiency.

Clinical applications of gene therapy mainly depend on the development of efficient gene transfer vectors. Large DNA molecules can only be transfected into cells by using synthetic vectors such as cationic lipids and polymers. The present investigation was therefore designed to explore the physicochemical properties of cationic lipid-DNA particles, with plasmids ranging from 900 to 52 500 bp. The colloidal stability of the lipoplexes formed by complexing lipopolyamine micelles with plasmid DNA of various lengths, depending on the charge ratio, resulted in the formation of three domains, respectively corresponding to negatively, neutrally and positively charged lipoplexes. Lipoplex morphology and structure were determined by the physicochemical characteristics of the DNA and of the cationic lipid. Thus, the lamellar spacing of the structure was determined by the cationic lipid and its spherical morphology by the DNA. The main result of this study was that the morphological and structural features of the lipopolyamine-DNA complexes did not depend on plasmid DNA length. On the other hand, their gene transfer capacity was affected by the size of plasmid DNA molecules which were sandwiched between the lipid bilayers. The most effective lipopolyamine-DNA complexes for gene transfer were those containing the shortest plasmid DNA.

3T3 Cells↗

PubMed1999

Periprosthetic fractures of the humerus and scapula: management and prevention.

The management of humerus fractures is complicated by the presence of a prosthesis. Vigilance in addressing the mechanisms and predisposing factors for periprosthetic fracture may prevent their occurrence. In the event of a periprosthetic fracture, attention to prosthetic stability, fracture location and stability, and bone quality will help guide treatment decisions. Treatment should be commensurate with the goals of fracture stability, early rehabilitation, and maintaining a well-functioning prosthesis.

Arthroplasty, Replacement↗

PubMed1999

pCOR: a new design of plasmid vectors for nonviral gene therapy.

A totally redesigned host/vector system with improved properties in terms of safety has been developed. The pCOR plasmids are narrow-host range plasmid vectors for nonviral gene therapy. These plasmids contain a conditional origin of replication and must be propagated in a specifically engineered E. coli host strain, greatly reducing the potential for propagation in the environment or in treated patients. The pCOR backbone has several features that increase safety in terms of dissemination and selection: (1) the origin of replication requires a plasmid-specific initiator protein, pi protein, encoded by the pir gene limiting its host range to bacterial strains that produce this trans-acting protein; (2) the plasmid's selectable marker is not an antibiotic resistance gene but a gene encoding a bacterial suppressor tRNA. Optimized E. coli hosts supporting pCOR replication and selection were constructed. High yields of supercoiled pCOR monomers were obtained (100 mg/l) through fed-batch fermentation. pCOR vectors carrying the luciferase reporter gene gave high levels of luciferase activity when injected into murine skeletal muscle.

Drug Design↗

PubMed1998

Topoisomerase I of Helicobacter pylori: juxtaposition with a flagellin gene (flaB) and functional requirement of a fourth zinc finger motif.

Cloning and nucleotide sequence analysis showed that in Helicobacter pylori the gene encoding topoisomerase I (topA) lies about 170 nucleotides upstream from flaB, a gene encoding one of the two flagellin proteins that is required for virulence. The topA and flaB genes are divergently transcribed. The orientation and spatial relationship between flaB and topA are remarkably conserved among strains of a bacterium in which genomic rearrangements are common. The deduced amino acid sequence of topoisomerase I revealed four zinc finger motifs, one more than has been reported previously for the Escherichia coli homologue. The additional motif, which is near the C-terminus of the protein, appears to be essential for function since mutations in that region are lethal. These data show that TopA proteins can be divided into several classes on the basis of zinc finger motifs and raise the interesting possibility that the H. pylori enzyme has local topological effects focussed on a flagellin gene.

Bacterial Proteins↗

PubMed1998

Production of a new DNA vehicle for gene transfer using site-specific recombination.

Supercoiled DNA molecules, minicircles, were produced by in vivo site-specific recombination. They contained exclusively the desired excisable fragment. Recombination was driven by bacteriophage lambda integrase from a plasmid substrate containing the attP and attB recombination sites in the same orientation. Conditions for minicircle production within the lysogen Escherichia coli D1210HP were optimised. Up to 1.5 mg minicircles could be produced per litre bacterial culture, and the remaining, unrecombined plasmid comprised less than about 15% of the minicircle produced. However minicircle multimers were also produced, and comprised up to 30% of all minicircles synthesised. The par ABCDE' locus from plasmid RK2 was introduced into the minicircle fragment, resulting in minicircle dimers being reduced to less than 2% of all minicircles. The par A gene encodes a resolvase that catalyses recombination at the multimer resolution site in the parABCDE' locus. Minicircle multimers were also resolved when par A was introduced downstream from the integrase gene of the lambda pL transcript in D1210HP together with a multimer resolution site carried by the minicircle fragment.

DNA, Circular↗

PubMed1998

Application of lipids and plasmid design for gene delivery to mammalian cells.

Cationic lipids are widely used for in vitro gene transfer due to their efficiency. The major challenges for the improvement of in vivo cationic lipid-mediated gene delivery reside in the design of more biocompatible lipoplexes mimicking viral-mediated gene delivery and in understanding the fate of the lipoplexes within the cells.

Animals↗

PubMed1998

Outcomes in rural obstetrics, Atherton Hospital 1981-1990.

Analysis of annual obstetric audit data collected over the decade 1981-1990 from the Atherton Hospital in far north Queensland provides evidence of safe obstetric practice provided by a group of non-specialist doctors in a rural community. During that period, there were 2883 deliveries with an overall perinatal mortality of 5.2/1000. There were 1974 public confinements (perinatal mortality 5.1/1000) and 909 private confinements (perinatal mortality 5.5/1000). By including those perinatal deaths that occurred in public patients who were transferred because of intrapartum complications, such as premature labour or neonatal problems, the corrected perinatal mortality rate for the public patients was 9.6/1000, which compares favourably with rates for Queensland and the Far North Statistical Division in 1987 of 13.5/1000 and 16.9/1000, respectively. This was achieved with low intervention, as indicated by an overall Caesarean section rate of 13.0% (public 10.6%, private 18.3%) and an antenatal referral rate of less than 2% of patients from the hospital public clinic for delivery under specialist care.

Adult↗

PubMed1997

Pediatric intestinal leiomyosarcomas: case report and review of the literature.

Primary intestinal leiomyosarcomas in children are rare tumors. Twenty-seven previous cases are documented in the literature with little information available on the treatment, survival, and prognostic factors surrounding these tumors. The authors report the 28th case of pediatric intestinal leiomyosarcoma and its follow-up, that of a newborn presenting with intestinal obstruction. Follow-up from all previously reported cases is not recorded and is needed. Our patient, like most children with this tumor, underwent complete excision with no evidence of recurrence at 5 years. Visceral metastases from these neoplasms are atypical, and recorded long-term prognosis may be favorable, unlike their counterpart in the adult population.

Humans↗

PubMed1997

A new DNA vehicle for nonviral gene delivery: supercoiled minicircle.

Plasmids currently used for nonviral gene transfer have the disadvantage of carrying a bacterial origin of replication and an antibiotic resistance gene. There is, therefore, a risk of uncontrolled dissemination of the therapeutic gene and the antibiotic resistance gene. Minicircles are new DNA delivery vehicles which do not have such elements and are consequently safer as they exhibit a high level of biological containment. They are obtained in E. coli by att site-specific recombination mediated by the phage lambda integrase. The desired eukaryotic expression cassette, bounded by the lambda attP and attB sites was cloned on a recombinant plasmid. The expression cassette was excised in vivo after thermoinduction of the integrase gene leading to the formation of two supercoiled molecules the minicircle and the starting plasmid lacking the expression cassette. In various cell lines, purified minicircles exhibited a two- to 10-fold higher luciferase reporter gene activity than the unrecombined plasmid. This could be due to either the removal of unnecessary plasmid sequences, which could affect gene expression or the smaller size of mini-circle which may confer better extracellular and intracellular bioavailability and result in improved gene delivery properties.

Cell Line↗