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Biomedical subjects

J Davison

Publications and source records attributed to J Davison.

At least 19 recordsLinked to original sources
PubMed2006

Genomic instability in Solanum tuberosum x Solanum kurtzianum interspecific hybrids.

The use of interspecific crosses in breeding is an important strategy in improving the genetic base of the modern cultivated potato, Solanum tuberosum L. Until now, it has normally been interspecific Solanum hybrids that have been morphologically and cytologically characterized. However, little is known about the genomic changes that may occur in the hybrid nucleus owing to the combination of genomes of different origin. We have observed novel AFLP bands in Solanum tuberosum x Solanum kurtzianum diploid hybrids; 40 novel fragments were detected out of 138 AFLP fragments analyzed. No cytological abnormalities were observed in the hybrids; however, we found DNA methylation changes that could be the cause of the observed genomic instabilities. Of 277 MSAP fragments analyzed, 14% showed methylation patterns that differed between the parental species and the hybrids. We also observed frequent methylation changes in the BC1 progeny. Variation patterns among F1 and BC1 plants suggest that some methylation changes occurred at random. The changes observed may have implications for potato breeding as an additional source of variability.

Animals↗
PubMed2003

Treatment of patients with advanced mycosis fungoides and Sézary syndrome with alemtuzumab.

OBJECTIVES: Alemtuzumab (anti-CD52, Campath-1H) has recently been shown to be effective in the treatment of a range of hematological malignancies, including B-cell chronic lymphocytic leukemia and T-cell prolymphocytic leukemia. We undertook a phase II study to evaluate the safety, tolerability and efficacy of alemtuzumab in patients with relapsed or refractory advanced stage cutaneous T-cell lymphoma. PATIENTS AND METHODS: A total of eight patients were enrolled, seven with mycosis fungoides/Sézary syndrome (MF/SS) and one with large-cell transformation of MF. Seven patients had disease refractory to multiple previous therapies. Alemzumab (30 mg) was administered intravenously three times per week for 12 wk or until maximum response. RESULTS: The overall response rate was 38%, with three patients achieving partial remission, two patients with stable disease and three patients with progressive disease (PD) during treatment. The time to progression was short, with all patients developing PD within 4 months of starting alemtuzumab. Response duration in the three PR patients was also brief, with responses lasting less than 3 months in all three cases. Significant hematological and immunosuppressive toxicity was observed, with both grade 3-4 cytopenias and significant infectious complications occurring in a majority of cases. CONCLUSIONS: Our findings suggest that in heavily pretreated, refractory, advanced stage MF/SS, although alemtuzumab has biological activity, it is associated with significant toxicity and only modest clinical utility. As such, combination regimens incorporating alemtuzumab merit further investigation in this difficult to treat patient group.

Adult↗
PubMed2001

Repetitive high-dose topotecan, carboplatin, and paclitaxel with peripheral blood progenitor cell support in previously untreated ovarian cancer: results of a Phase I study.

OBJECTIVE: In view of the significant activity of topotecan in ovarian cancer with dose-limiting toxicity (DLT) of myelosuppression, we evaluated the addition of topotecan to carboplatin and paclitaxel with peripheral blood progenitor cell (PBPC) support. METHODS: Patients with previously untreated stage IIIC or IV ovarian cancer with macroscopic residual disease following primary debulking surgery were eligible. Patients received two cycles of carboplatin AUC = 5 and 175 mg/m(2) of paclitaxel with collection of PBPCs after the second cycle. Patients subsequently received three cycles of high-dose therapy (HDT) with topotecan on a daily x5 schedule, paclitaxel (250 mg/m(2) over 24 h), and carboplatin (AUC = 12-16). RESULTS: Nineteen patients with a median age of 49 years (range 21-63) were enrolled and topotecan was escalated in 6 patient cohorts up to a dose of 4.5 mg/m(2)/day. Fifty-two of the planned 57 treatment cycles were delivered with no treatment-related deaths. Neutrophil and platelet recovery was rapid and the interval between HDT was 28 days. Febrile neutropenia occurred following 57% of all HDT cycles. DLTs of mucositis and diarrhea were observed at topotecan (4.5 mg/m(2)/day), paclitaxel (250 mg/m(2)) and carboplatin (AUC = 12). The protocol was subsequently modified to administer topotecan (2.5 mg/m(2)/day) with carboplatin (AUC = 16); however, 2 patients developed grade 4 diarrhea (1 with grade 3 mucositis and 1 with grade 4 mucositis). The clinical CR rate was 73% (14/19) with an overall clinical response rate of 95% (18/19). Of the 14 patients with a CCR, 13 of these underwent a second-look laparotomy with 8 (61%) achieving a pathological CR. With a median follow-up of 28 months (range 11-40 months), the median PFS is 36 months and OS has not been reached. CONCLUSION: When combined with carboplatin (AUC = 12) and paclitaxel (250 mg/m(2)), the recommended topotecan dose is 3.5 mg/m(2)/day for 5 days. This outpatient HDT regimen combines three of the most active drugs in ovarian cancer with acceptable toxicity and promising activity.

Adult↗
PubMed2001

Management of a pregnant patient with Graves' disease complicated by thionamide-induced neutropenia in the first trimester.

A 31-year-old woman presented with neutropenia due to thionamide drug therapy for Graves' disease. She also reported 8 weeks of amenorrhoea and had a positive pregnancy test. Her drug therapy was discontinued and her neutropenia resolved uneventfully. The hyperthyroidism recurred a week later. After consideration of all treatment options, it was decided to observe until 14 weeks when an elective thyroidectomy was planned. Mother and fetus were monitored closely and both tolerated moderate hyperthyroidism well. At 14 weeks the patient underwent a total thyroidectomy after rendering her euthyroid with a short course of sodium ipodate. Labour was induced at 41 weeks. Delivery was complicated by fetal distress and precipitated a forceps delivery. A 3250 g male infant was born with poor Apgar score and required 2 h of ventilation. At 1 year, the child had reached all developmental milestones at appropriate times. Both mother and fetus may tolerate moderate thyrotoxicosis well in early pregnancy, an alternative that should be considered when thionamide drug therapy is contraindicated.

Adult↗
PubMed2001

Bexarotene capsules and gel for previously treated patients with cutaneous T-cell lymphoma: results of the Australian patients treated on phase II trials.

Bexarotene (Targretin, LGD1069) is a novel synthetic retinoid analogue that binds selectively to retinoid X receptors. We describe eight previously treated patients who entered phase II international multicentre studies examining the role of bexarotene in cutaneous T-cell lymphoma. Patients received either the oral formulation (n = 7) or the topical gel (n = 1). Of the seven patients who received 300 mg/m2 per day capsules, five (71%) achieved a partial response, with mean time to onset of response of 27 days (range, 20-29) with responses persisting for a mean of 92 days (range, 57-115). The single patient receiving the topical preparation (stage IB) remains in partial response at 31 months. The major toxicity with oral administration was hypertriglyceridaemia requiring therapy. Bexarotene capsules and gel are active and generally well-tolerated agents in patients with cutaneous T-cell lymphoma and studies examining its role in previously untreated patients or as part of combination therapy are warranted.

Administration, Oral↗
PubMed2001

Hypocalcemic and normocalcemic hyperparathyroidism in patients with advanced prostatic cancer.

PTH and ionized calcium levels were measured in 131 patients with advanced prostate cancer, all of whom had received at least first-line hormone therapy. Patients were classified into those in remission, those with stable disease, or those with progressive disease according to their prostate-specific antigen response and their clinical status. Thirty-four percent of all patients had PTH levels above the upper level of normal for controls of similar age (7.0 pmol/liter), and in 44% of these patients this was associated with a normal ionized calcium. Patients with proven bone metastases had significantly higher PTH levels than those without. (7.3 +/- 0.5 vs. 4.3 +/- 0.4 pmol/liter, P < 0.0005). There was evidence for a difference in the PTH levels between the three response groups. The PTH levels tended to be higher in patients with progressive disease. Thirty-seven of 65 patients (57%) with both progressive disease and proven bone metastases had elevated PTH levels. Mean levels of urinary deoxypyridinoline and cAMP were significantly greater in patients with high PTH than in those with a normal PTH. Treatment with oral calcium supplements in 32 patients with a high PTH seemed to have only a transient effect on elevated PTH or low ionized calcium levels. These data show that secondary hyperparathyroidism occurs frequently in patients with advanced prostate cancer, particularly in those with both progressive disease and bone metastases. The increased PTH levels are associated with an increase in bone resorption markers. These findings raise important questions about the role of PTH in progression of prostatic cancer in bone and the potential limitations of the use of bisphosphonates in patients with a raised PTH or low serum calcium.

Aged↗
PubMed2000

DNA contamination of mortuary instruments and work surfaces: a significant problem in forensic practice?

A study of 20 mortuaries was undertaken to assess whether contamination of instruments, tables and cutting areas due to residual material containing human DNA after routine cleaning is an actual or only a theoretical problem. Of the 20 mortuaries studied, 50% were found to have material containing quantifiable human DNA on the instruments and surfaces sampled. This DNA was amplified and found, in some cases, to have been derived from at least three people. Of those that did not yield measurable amounts of DNA, a number of samples were selected at random, amplified and were found to produce partial profiles indicating the presence of low levels of human DNA. The possible sources of human DNA from mortuaries are discussed as well as means to reduce or irradicate the problem of instrument contamination. Finally the implications of these findings for forensic investigations are discussed.

Autopsy↗
PubMed2000

A phase I trial of docetaxel and gemcitabine in patients with advanced cancer.

BACKGROUND: Docetaxel and gemcitabine are active in a broad range of malignancies. The objective of this phase I trial was to determine the maximally tolerated doses of the combination of docetaxel and gemcitabine. PATIENTS AND METHODS: Patients with advanced cancer, WHO performance status 0-2, who had received up to one prior chemotherapy regimen were treated with gemcitabine on days 1 and 8 and docetaxel on day 8 repeated every 21 days. Prophylactic ciprofloxacin was commenced on day 11 of each cycle and continued until the neutrophil count reached 1.0 x 10(9)/l. G-CSF was not administered. Dose levels studied were docetaxel/gemcitabine: 60/800, 60/1000, 75/1000, 75/1200, 85/1200 and 100/1200 mg/m2. RESULTS: Thirty-nine patients were entered and all were assessable for toxicity. The highest administered dose level was 100 mg/m2 docetaxel and 1200 mg/m2 gemcitabine with dose limiting toxicities of febrile neutropenia, grade 4 neutropenia > or = 7 days, grade 4 thrombocytopenia, grade 3 stomatitis and/or grade 3 fatigue in three out of six patients. Treatment was well tolerated (40 cycles) in the 10 patients treated at the recommended dose level (85/1200) with only a single episode of febrile neutropenia and grade 3 or 4 non-hematologic toxicity was infrequent. There was no significant pulmonary toxicity. Responses were seen in a range of malignancies including non-small-cell lung cancer. CONCLUSIONS: The recommended dose level of 85 mg/m2 docetaxel and 1200 mg/m2 gemcitabine has a favourable toxicity profile and is suitable for further investigation in phase II trials. This non-platinum containing regimen warrants further investigation as a potential alternative to platinum containing regimens in non-small-cell lung cancer and other malignancies.

Adult↗
PubMed1999

Genetic exchange between bacteria in the environment.

Nucleotide sequence analysis, and more recently whole genome analysis, shows that bacterial evolution has often proceeded by horizontal gene flow between different species and genera. In bacteria, gene transfer takes place by transformation, transduction, or conjugation and this review examines the roles of these gene transfer processes, between different bacteria, in a wide variety of ecological niches in the natural environment. This knowledge is necessary for our understanding of plasmid evolution and ecology, as well as for risk assessment. The rise and spread of multiple antibiotic resistance plasmids in medically important bacteria are consequences of intergeneric gene transfer coupled to the selective pressures posed by the increasing use and misuse of antibiotics in medicine and animal feedstuffs. Similarly, the evolution of degradative plasmids is a response to the increasing presence of xenobiotic pollutants in soil and water. Finally, our understanding of the role of horizontal gene transfer in the environment is essential for the evaluation of the possible consequences of the deliberate environmental release of natural or recombinant bacteria for agricultural and bioremediation purposes.

Animals↗
PubMed1999

Integration of neuro-endocrine immune responses in defense of mucosal surfaces.

Neuro-endocrine immunology, a field arising from curiosity about the mind-body connection, is evolving rapidly. From intriguing, but seemingly unexplainable observations with human infections and disease, experimental systems have been developed that provide a solid scientific basis for new understanding. There have been major efforts to understand influences of the nervous system on immune and inflammatory responses, e.g., innervation of the immune system, molecular communication pathways, and complex phenomena such as conditioning of immune responses and mechanisms of host defenses. In turn, the immune system communicates with the neuro-endocrine systems. Imbalances in the neuro-endocrine-immunologic circuitry are relevant in host defenses and in injury and repair. Examples of these themes in neuro-endocrine-immunology arise in several host-parasite models of neurogenic inflammation, immediate hypersensitivity responses, and granuloma formation. The hypothalamic-pituitary-adrenal axis and the cervical sympathetic trunk-submandibular gland axis provide important models to enhance understanding of this poorly known component of the host-parasite relationship.

Animals↗
PubMed1998

Development and validation of an evaluation tool for multimedia resources in health education.

The last decade saw a rapid increase in the use of multimedia in health education. Easy availability, accessibility, low cost of technological resources and the expanding body of research on the role of multimedia in student learning, among others, have all contributed to this increase in usage. Since one of the roles of educators is to assess and select learning resources based on curriculum goals and student needs, the development of standardized methods for multimedia evaluation becomes vital. To the learner, it is important for reviews of the quality of the resource to be readily available. An evaluation too was developed based on the recognition of this need. The validity of the tool was tested using experts in technology and education. Reliability was determined using faculty and students who reviewed the same software, using the tool. In addition, graduate students reviewed two versions of a nursing program, of varying quality. The results indicate that the tool is reliable and valid. It is envisaged that this tool can be utilized by health educators for evaluating multimedia resources and setting up a much needed clearinghouse for health education resources.

CD-ROM↗
PubMed1997

Relationship between effect of ethanol on proton flux across plasma membrane and ethanol tolerance, in Pichia stipitis.

Pichia stipitis efficiently converts glucose or xylose into ethanol but is inhibited by ethanol concentrations exceeding 30 g/L. In Saccharomyces cerevisiae, ethanol has been shown to alter the movement of protons into and out of the cell. In P. stipitis the passive entry of protons into either glucose- or xylose-grown cells is unaffected at physiological ethanol concentrations. In contrast, active proton extrusion is affected differentially by ethanol, depending on the carbon source catabolized. In fact, in glucose-grown cells, the H(+)-extrusion rate is reduced by low ethanol concentrations, whereas, in xylose-grown cells, the H(+)-extrusion rate is reduced only at non-physiological ethanol concentrations. Thus, the ethanol inhibitory effect on growth and ethanol production, in glucose-grown cells, is probably caused by a reduction in H(+)-extrusion. Comparison of the rates of H(+)-flux with the related in vitro H(+)-ATPase activity suggests a new mechanism for the regulation of the proton pumping plasma membrane ATPase (EC 3.6.1.3) of P. stipitis, by both glucose and ethanol. Glucose activates both the ATP hydrolysis and the proton-pumping activities of the H(+)-ATPase, whereas ethanol causes an uncoupling between the ATP hydrolysis and the proton-pumping activities. This uncoupling may well be the cause of ethanol induced growth inhibition of glucose grown P. stipitis cells.

Journal Article↗
PubMed1997

Domestic violence: the nursing response.

Nursing's response to victims of domestic violence may reflect that of society, with victim-blaming and reluctance to become involved being major problems. Nurses should improve their awareness in this area and call for training in dealing with such patients. Nurses should become involved in drawing up guidelines for practice in this area.

Clinical Competence↗
PubMed1992

Cloning and sequencing of Pseudomonas genes determining sodium dodecyl sulfate biodegradation.

The nucleotide sequences of two genes involved in sodium dodecyl sulfate (SDS) degradation, by Pseudomonas, have been determined. One of these, sdsA, codes for an alkyl sulfatase (58,957 Da) and has similarity (31.8% identity over a 201-amino acid stretch) to the N terminus of a predicted protein of unknown function from Mycobacterium tuberculosis. The other gene, sdsB, codes for a positive activator protein (33,600 Da) that has extensive similarity with the lysR family of helix-turn-helix DNA-binding activator proteins.

Amino Acid Sequence↗
PubMed1991

Transposon vectors for stable chromosomal integration of cloned genes in rhizosphere bacteria.

A series of Tn5-based transposon-cloning vectors, in which many unique restriction sites lie within the transposon, have been constructed. These transposon vectors can be delivered, by conjugation, using a delivery vehicle containing a pBR322 replicon and the mobilization genes of plasmid RK2. In Pseudomonas sp., this delivery vehicle acts as a suicide plasmid, permitting transposition to the chromosome to be detected. To facilitate cloning into the transposon vector, the delivery vehicle has been simplified so that the useful cloning sites in the transposon are not duplicated. As a model system for the transposition of cloned genes, the xylE (coding for catechol-2,3-dioxygenase) has been transposed to a variety of Pseudomonads. The transposon vectors should be useful when a stable single copy of a cloned gene is desired. They should be particularly advantageous for the genetic engineering of soil bacteria for environmental studies (agriculture or pollution control) where the stability of the engineered strains, in the absence of continuous antibiotic selection, may be important.

Blotting, Southern↗