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Biomedical subjects

D Anderson

Publications and source records attributed to D Anderson.

At least 181 records · Page 10Linked to original sources
PubMed1998

Function of hexameric RNA in packaging of bacteriophage phi 29 DNA in vitro.

A cyclic hexamer of the 120-base prohead RNA (pRNA) is needed for efficient in vitro packaging of the B. subtilis bacteriophage phi 29 genome. This capacity of pRNA to form higher multimers by intermolecular base pairing of identical subunits represents a new RNA structural motif. Dimers of pRNA are likely intermediates in formation of the cyclic hexamer. A three-dimensional model of the pRNA hexamer is presented.

Bacillus Phages↗
PubMed1998

A new ambulatory classification and funding model for radiation oncology: non-admitted patients in Victorian hospitals.

The Victorian Department of Human Services has developed a classification and funding model for non-admitted radiation oncology patients. Agencies were previously funded on an historical cost input basis. For 1996-97, payments were made according to the new Non-admitted Radiation Oncology Classification System and include four key components. Fixed grants are based on Weighted Radiation Therapy Services targets for megavoltage courses, planning procedures (dosimetry and simulation) and consultations. The additional throughput pool covers additional Weighted Radiation Therapy Services once targets are reached, with access conditional on the utilisation of a minimum number of megavoltage fields by each hospital. Block grants cover specialised treatments, such as brachytherapy, allied health payments and other support services. Compensation grants were available to bring payments up to the level of the previous year. There is potential to provide incentives to promote best practice in Australia through linking appropriate practice to funding models. Key Australian and international developments should be monitored, including economic evaluation studies, classification and funding models, and the deliberations of the American College of Radiology, the American Society for Therapeutic Radiology and Oncology, the Trans-Tasman Radiation Oncology Group and the Council of Oncology Societies of Australia. National impact on clinical practice guidelines in Australia can be achieved through the Quality of Care and Health Outcomes Committee of the National Health and Medical Research Council.

Abstracting and Indexing↗
PubMed1998

Optimization of sacral ventral root stimulation following SCI: two case reports with six-month follow-up.

Sacral ventral root stimulation in conjunction with sacral dorsal rhizotomy has been effective in promoting voiding in individuals with upper-motor-neuron spinal cord injury. We report on two patients who had variable voiding responses to stimulation during the first six months after electrode implantation. We used videourodynamic records and daily voiding records to characterize their voiding difficulties. Different methods were used to improve voiding, including seating adjustments and changes in stimulation parameters. The first patient was unable to empty his bladder on a regular basis with stimulation using 24 pulses per sec stimulating frequency for the first two months after implantation. Voiding was substantially improved by using 35 pulses per sec. At the end of six months, he is regularly emptying his bladder with stimulation and is on an every-second-day bowel program. However, his bowel program has been irregular. The second patient had very good voiding when stimulation was applied in bed, but he had poor voiding with high residual volumes when sitting in his wheelchair. Voiding was improved when he used a wheelchair cushion that was cut out in the back or lifted his buttocks off the chair. These procedures appeared to reduce perineal pressures. This patient has bowel care on alternate days and his bowel care time has been reduced following implantation of the device. Neither of the patients experienced an erection with the device. Both patients feel positive about their implant experience.

Electric Stimulation Therapy↗
PubMed1998

The International Comet Assay Workshop.

The Comet (single cell gel electrophoresis) assay primarily measures DNA strand breakage in single cells (Singh et al., 1988). Briefly, cells are suspended in low melting point agarose on a microscope slide. The slides are put in lysing buffer to allow the DNA to unwind and then in electrophoresis buffer. During electrophoresis the broken DNA moves towards the anode forming a Comet tail, with the greater the extent of damage, the greater the tail. Assays can be conducted under neutral or alkaline (> pH 13) conditions. Double-strand breaks are measured under neutral conditions and single-strand breaks under alkaline conditions, where abasic sites and other alkali-labile sites or intermediates in base or nucleotide excision repair can also be detected. There are several good reviews concerning the assay (McKelvey-Martin et al., 1993; Fairbairn et al., 1995; Tice, 1995).

Cell Extracts↗
PubMed1998

Calibration of the single cell gel electrophoresis assay, flow cytometry analysis and forward mutation in Chinese hamster ovary cells.

The induction kinetics of genetic damage were measured in one clone of a mammalian cell line (CHO AS52) with three genotoxicity assays, the single cell gel electrophoresis (Comet) assay, laser beam flow cytometry and forward mutation. The first two assays allow for the rapid analysis of genotoxic damage in individual nuclei. The alkaline Comet assay detects DNA strand breaks, alkali-labile sites and incomplete excision repair sites. Flow cytometry measures chromosome damage that results in an unequal distribution of nuclear DNA in daughter cells. We calibrated these assays to compare acute DNA damage and longer term clastogenicity with forward mutation at the gpt locus using ethyl methanesulfonate (EMS). The EMS treatments were conducted in F12 medium for 2 h. AS52 cells carry a single functional gpt gene which provides for quantitation of gpt mutants by selecting for 6-thioguanine resistance. EMS induced a concentration-dependent response with median Comet tail moment values of 1.06 microns for the negative control and 64.6 microns with 20 mM. The coefficient of variation (CV) of the negative-control with flow cytometry was 2.33; the CV value increased to 4.87 in cells treated with 20 mM EMS, EMS (8 mM) induced a mutant frequency of 779.8 x 10(-6) at a relative survival of 64.4%. Genetic response factors were calculated and the data demonstrate that the induction kinetics of genetic damage as measured by the Comet assay (15.6) and flow cytometry (14.2) were more closely related than that determined for mutation induction (7.9). These three assays measure a wide spectrum of genetic events at the level of DNA, the gene and the chromosome and demonstrate the usefulness of the Comet assay and flow cytometry as two relatively rapid procedures to detect genotoxic damage in mammalian cells.

Animals↗
PubMed1998

Comet assay responses as indicators of carcinogen exposure.

Over 200 agents/factors have been examined in the single cell gel electrophoresis assay, more commonly known as the Comet assay, performed either in vitro or in vivo in a variety of species. Unequivocal carcinogenicity data are available for 119 of them, amongst which unequivocal Comet assay data exist for 95 agents. Of these 95 agents the prevalence of carcinogens was 88% (84/95). The carcinogens that were Comet positive (sensitivity) formed 88% (74/84), the non-carcinogens that were Comet negative (specificity) formed 64% (7/11). This simple analysis of the Comet assay has not taken account of the difference between in vitro and in vivo responses, species differences or organ and tissue differences. Also, limitations as to the conduct of the assay have not been examined in any depth. Thus, at the present time the Comet assay has high sensitivity for carcinogens, but its specificity is uncertain because few non-carcinogens have been tested.

Animals↗
PubMed1998

Cerebral fungal infections in the immunocompromised host: a literature review and a new pathogen--Chaetomium atrobrunneum: case report.

OBJECTIVE AND IMPORTANCE: A case of a cerebral abscess, occurring in a patient who had undergone bone marrow transplant, caused by a new pathogen, Chaetomium atrobrunneum, and a review of the literature are presented. Although Aspergillus species are by far the most common fungi found in cerebral abscesses in immunocompromised patients, an increasing number of fungi commonly found in nature but not usually associated with infections in humans have been isolated from cerebral abscesses in these patients. CLINICAL PRESENTATION: A 31-year-old male patient, who had undergone a recent bone marrow transplantation for multiple myeloma, presented 3 months after transplantation with right-sided hemiplegia caused by a left parietal hemorrhagic lesion. INTERVENTION: A biopsy guided by computed tomography showed that the abscess contained the fungus C. atrobrunneum. The final identification of the organism was based on cultures, scanning electron microscopic studies, and consultation with the Fungus Testing Laboratory at the University of Texas Health Science Center, San Antonio, TX. The patient was treated with several antifungal medications but developed uncontrolled cerebral edema, which led to further neurological deterioration and eventual death. CONCLUSION: Cerebral abscesses in the immunocompromised patient may no longer be assumed to be caused solely by Aspergillus species. The literature reveals several rare cases of uncommon fungi found in these abscesses. Only four cases of cerebral infections caused by the genus Chaetomium have been reported. The case presented represents the first time a patient who had undergone a bone marrow transplant with a cerebral abscess was found to be caused by the pathogen C. atrobrunneum.

Adult↗
PubMed1998

Streptococcal peritonitis in a young dromedary camel.

A male dromedary camel was presented for a primary Streptococcal zooepidemicus septic peritonitis. An underlying gross lesion was not identified during abdominal exploratory surgery. The camel responded to peritoneal lavage, peritoneal drainage and systemic antibiotic therapy. Thrombophlebitis of the left jugular vein was diagnosed 14 days after surgery. The camel died of an unknown cause 24 days after surgery.

Animals↗
PubMed1998

Peripherally inserted central venous catheters: factors affecting patient satisfaction.

OBJECTIVE: We studied factors that affect satisfaction of patients who have undergone placement of peripherally inserted central venous catheters (PICCs) by interventional radiologists and patients' willingness to undergo placement of future PICCs. SUBJECTS AND METHODS: This longitudinal prospective consecutive cohort study included 85 patients referred for PICC placement. A record was made of catheter type, time taken for placement, patient age, and possible complications. Follow-up was obtained by telephone interview to determine the effect of site of placement in the arm, residence time of catheter, additional complications, and interference with activities of daily living on patient willingness to undergo future PICC placement at the same site. Logistic regression analysis was used to determine factors statistically predictive of patient willingness to undergo placement of future PICCs. RESULTS: Patients having PICCs placed above the elbow were more often satisfied (55 of 61 respondents) with catheter location than patients having placements at the elbow (three of 17 respondents). Patient willingness to undergo future PICC placement was strongly related to catheter location (p < .0001) and interference with activities of daily living (p < .0001). Catheter type, residence time, time taken for the placement, age, and complications were not associated with patient willingness to undergo future PICC placement. CONCLUSION: PICC placement above the elbow is more acceptable to patients than placement at the elbow. PICC placement above the elbow and patients' perception of less interference by the PICC with activities of daily living are positively related to patient willingness to undergo future PICC placement.

Activities of Daily Living↗
PubMed1998

Five- and eight-month-old infants recognize their faces and voices as familiar and social stimuli.

Five- and 8-month-old infants were presented with silent moving and static video images of self, peer, and doll and with sounds of self, peer, and nonsocial objects. In the visual conditions, infants at both ages showed a significant looking preference to peer over self when the faces were moving. When the faces were static, older infants showed the same significant discriminations, but the younger infants showed a significant looking preference for their own faces over peer and doll. These data suggest that recognition of one's own image develops through experience with dynamic facial stimulation during the first 8 months of life. In the auditory conditions, infants at both ages showed significant looking preferences for sounds of peer over self or nonsocial objects. In general, infants of both ages smiled and produced more vocalizations to social faces and social sounds than to nonsocial faces and nonsocial sounds. Thus, at 5 months infants treat their faces and voices as familiar and social stimuli. The findings forge important links among studies of self-perception, self-recognition, and social knowledge.

Child Development↗
PubMed1998

Evaluating hoarseness: keeping your patient's voice healthy.

Hoarseness is the term often used by patients to describe changes in their voice quality. The causes of hoarseness are determined after obtaining a detailed medical history of the circumstances preceding the onset of hoarseness and performing a thorough physical examination. The latter may include visualization of the vocal cords, possibly using indirect laryngoscopy, flexible nasolaryngoscopy or strobovideolaryngoscopy. In the absence of an upper respiratory tract infection, any patient with hoarseness persisting for more than two weeks requires a complete evaluation. When the patient has a history of tobacco use, cancer of the head and neck must be considered and ruled out. Voice abuse is one of the most common causes of hoarseness and can lead to other vocal pathologies such as vocal nodules. Good vocal hygiene can prevent and treat some pathologies, and voice therapy is a cornerstone of management in some cases of hoarseness.

Adult↗
PubMed1998

Modulation of ras p21 oncoprotein levels and DNA strand breakage in human cells with chemotherapeutic agents and/or deferoxamine.

Oncogenes are involved with the regulation of cellular proliferation. Ras oncogenes can be activated by chemical treatment and any increased activity could be modulated by further chemical treatment. In the present study, therefore, ras p21 protein expression was examined in in vitro cultures of human lymphocytes treated with mitomycin C and in the human colon adenocarcinoma Caco-2 cell line treated with doxorubicin with and without deferoxamine. Both chemotherapeutic agents act partially through oxygen radical mechanisms. Increases in p21 protein levels were seen with mitomycin C but no clear response was seen with doxorubicin. However, deferoxamine, with and without doxorubicin, altered p21 expression. Deferoxamine is an iron chelator so these results support the hypothesis that oxygen radicals were responsible for the altered p21 protein levels. Modulating responses were confirmed by measuring DNA strand-breakage in the Comet assay after treatment with doxorubicin and deferoxamine. Alterations of ras p21 protein expression in vitro might prove a suitable system for examining modulating effects on chemical carcinogens.

Antineoplastic Agents↗
PubMed1998

Analysis of mutagens with single cell gel electrophoresis, flow cytometry, and forward mutation assays in an isolated clone of Chinese hamster ovary cells.

We investigated the induction of DNA strand breaks in the single cell gel electrophoresis (SCGE or comet) assay with whole cell clastogenicity measured with flow cytometric analysis in cells from an isolated clone of the Chinese hamster ovary (CHO) AS52 cell line. Under identical treatment conditions the responses were compared with forward mutation at gpt using 2-acetoxyacetylaminofluorene (2AAAF), ultraviolet radiation (UV) and ethyl methanesulfonate (EMS). Cytotoxicity for each agent was evaluated in the SCGE and forward mutation assays. Forward mutation was 4-10-fold more sensitive than DNA strand breaks detected in the SCGE assay. For 2AAAF and EMS, the kinetics of the induction of genetic damage were similar for the three assays, although there were differences in sensitivity. With UV, the induction kinetics of gpt mutation differed from that expressed by SCGE and flow cytometric analysis. With the chemical mutagens 2AAAF and EMS, there was a high correlation between the SCGE assay and forward mutation and also between the SCGE assay and flow cytometry. There was no significant correlation between flow cytometry and forward mutation. With UV, only the SCGE assay and flow cytometry were correlated. Agent-specific variations in the intragenomic distribution of DNA damage for each mutagen was measured in the SCGE assay.

Acetoxyacetylaminofluorene↗
PubMed1997

Examination of ras (P21) proteins in plasma from workers exposed to benzene emissions from petrochemical plants and healthy controls.

Exposure of workers to benzene and polyaromatic hydrocarbons has been documented to be at relatively high levels in the production of benzene and in the coking process at a petrochemical plant in the oil shale area in Estonia. Altogether 97 plasma samples from workers and 40 from unexposed matched referents from two samplings in different seasons were analyzed for the presence of ras (P21) proteins; of the workers 50 were exposed to benzene in the benzene production plant and 47 to polyaromatic hydrocarbons and benzene in a cokery. Proteins were separated by gel electrophoresis, transferred to a nitrocellulose membrane by Western blotting and detected by chemiluminescence, using a monoclonal antibody as the primary antibody. There were no statistically significant differences between the exposed and the referent groups. The results are thus in keeping with the lack of exposure related cytogenetic effects for this same workforce.

Adult↗